[
    {
        "anchor": "Emergence of Dirac-like bands in the monolayer limit of epitaxial Ge\n  films on Au(111): After the discovery of Dirac fermions in graphene, it has become a natural\nquestion to ask whether it is possible to realize Dirac fermions in other\ntwo-dimensional (2D) materials as well. In this work, we report the discovery\nof multiple Dirac-like electronic bands in ultrathin Ge films grown on Au(111)\nby angle-resolved photoelectron spectroscopy. By tuning the thickness of the\nfilms, we are able to observe the evolution of their electronic structure when\npassing through the monolayer limit. Our discovery may signify the synthesis of\ngermanene, a 2D honeycomb structure made of Ge, which is a promising platform\nfor exploring exotic topological phenomena and enabling potential applications.",
        "positive": "High Curie temperature and perpendicular magnetic anisotropy in\n  homoepitaxial InMnAs films: We have prepared the dilute magnetic semiconductor (DMS) InMnAs with\ndifferent Mn concentrations by ion implantation and pulsed laser melting. The\nCurie temperature of the In1-xMnxAs epilayer depends on the Mn concentration x,\nreaching 82 K for x=0.105. The substitution of Mn ions at the Indium sites\ninduces a compressive strain perpendicular to the InMnAs layer and a tensile\nstrain along the in-plane direction. This gives rise to a large perpendicular\nmagnetic anisotropy, which is often needed for the demonstration of electrical\ncontrol of magnetization and for spin-transfer-torque induced magnetization\nreversal."
    },
    {
        "anchor": "On the influence of Al-concentration on the fracture toughness of NiAl:\n  microcantilever fracture tests and atomistic simulations: The mechanical properties of the stoichiometric B2 $\\beta$-phase of NiAl are\nwell established, however the effect of off-stoichiometric composition on the\nfracture toughness has not yet been systematically studied over the entire\ncomposition range of 40-50% Al. Here we use microbending tests on notched\ncantilever beams FIB-milled from NiAl single crystals with an aluminized as\nwell as an oxidation-induced composition gradient to determine the influence of\nthe Al concentration on the mechanical properties. The fracture toughness is\nmaximal for the stoichiometric composition. It decreases with increasing\nNi-content in the Ni-rich composition range, where plastic deformation is\nobserved to accompany the fracture process. In contrast, no plasticity is\nobserved in Al-rich NiAl, which shows a nearly concentration-independent, low\nfracture toughness. The theoretical fracture toughness according to Griffith,\nhowever, shows only a very weak composition dependence in both, the Ni- and\nAl-rich composition range. The differences in fracture toughness could\nfurthermore not be explained solely based on the different hardening\ncontributions of Ni-antisites in the Ni-rich and structural vacancies in the\nAl-rich crystals. Atomistic fracture simulations show that crack propagation in\nNiAl takes place by the nucleation and migration of kinks on the crack front.\nThe low fracture toughness of Al-rich NiAl can thus be understood by the dual\neffect of structural vacancies as strong obstacles to dislocation motion and as\nsource of crack front kinks.",
        "positive": "Local Dielectric Measurements of BaTiO3-CoFe2O4 Nano-composites Through\n  Microwave Microscopy: We report on linear and non-linear dielectric property measurements of BaTiO3\n- CoFe2O4 (BTO-CFO) ferroelectro-magnetic nano-composites and pure BaTiO3 and\nCoFe2O4 samples with Scanning Near Field Microwave Microscopy. The permittivity\nscanning image with spatial resolution on the micro-meter scale shows that the\nnano-composites have very uniform quality with an effective dielectric constant\n\\epsilon_r = 140 +/- 6.4 at 3.8 GHz and room temperature. The temperature\ndependence of dielectric permittivity shows that the Curie temperature of pure\nBTO was shifted by the clamping effect of the MgO substrate, whereas the Curie\ntemperature shift of the BTO ferroelectric phase in BTO-CFO composites is less\npronounced, and if it exists at all, would be mainly caused by the CFO.\nNon-linear dielectric measurements of BTO-CFO show good ferroelectric\nproperties from BTO."
    },
    {
        "anchor": "Modeling Self-Healing Behavior of Vitrimers using Molecular Dynamics\n  with Dynamic Cross-Linking Capability: Vitrimers are a special class of polymers that undergo dynamic cross-linking\nunder thermal stimuli. Their ability to exchange covalent bonds can be\nharnessed to mitigate damage in a composite or to achieve recyclable aerospace\ncomposites. This work addresses the primary challenge of modeling dynamic\ncross-linking reactions in vitrimers during thermomechanical loading. Dynamic\nbond exchange reaction probability change during heating and its effect on\ndilatometric and mechanical response are simulated for the first time in large\nscale molecular dynamics simulations. Healing of damage under thermal cycling\nis computed with mechanical properties predicted before and after\nself--healing.",
        "positive": "First-principles Study of Spin-wave Excitations of 3$d$ Transition\n  Metals with Linear Combination of Pseudo-atomic Orbitals: We have employed the generalized Bloch theorem to evaluate the spin stiffness\nconstants of 3$d$ transition metals (bcc-Fe, fcc-Co, and fcc-Ni) within the\nlinear combination of pseudo-atomic orbitals (LCPAO). The spin stiffness\nconstants were obtained by fitting the spin-wave energy curve, which relates to\nthe total energy difference and the spiral vectors. In order to convince the\nreliable spin stiffness constants, we also provided the convergences of spin\nstiffness constants in terms of the cutoff radius and the number of orbitals.\nAfter observing the specific cutoff radius and the basis orbital, at which the\nspin stiffness constant converges, we used those two parameters to compute the\nCurie temperature by using the mean field approximation and the random phase\napproximation. For the latter approximation, we applied the so-called Debye\napproximation, which is intended to reduce very significantly many required\nwavevectors to evaluate the Curie temperature. We claimed that our results are\nin good agreement with both other calculations and experiments."
    },
    {
        "anchor": "Structure Determination in a new Type of Amorphous Molecular Solids with\n  Different Nonlinear Optical Properties: A Comparative Structural Analysis: The microscopic structure of two amorphous materials with extreme nonlinear\noptical properties has been studied. One of these materials exhibits second\nharmonic generation, while another material of similar molecular structure\nemits brilliant white light if being irradiated with a simple IR laser diode.\nStructural differences were investigated using X-ray scattering and EXAFS\ncombined with molecular RMC. Transmission electron microscopy and scanning\nprecession electron diffraction were used to understand specific structural\ndifferences on all length scales, from mesoscopic down to mutual molecular\narrangements. Characteristic differences were found at all scales. Close\ncore-core spacing between {SnS} clusters as well as characteristic cluster\ndistortions appear to be characteristic features of the white light emitting\nmaterial. In the other material, cores are undistorted and core distances are\nlarger. There, the formation of nanocrystalline structures in the amorphous\nmatrix could also be identified as reason for the WLG suppression.",
        "positive": "Competing Ferromagnetic and Anti-Ferromagnetic interactions in Iron\n  Nitride $\u03b6$-Fe$_2$N: The paper discusses the magnetic state of zeta phase of iron nitride viz.\n$\\zeta$-Fe$_2$N on the basis of spin polarized first principles electronic\nstructure calculations together with a review of already published data.\nResults of our first principles study suggest that the ground state of\n$\\zeta$-Fe$_2$N is ferromagnetic (FM) with a magnetic moment of 1.528\n$\\mu_\\text{B}$ on the Fe site. The FM ground state is lower than the\nanti-ferromagnetic (AFM) state by 8.44 meV and non-magnetic(NM) state by 191\nmeV per formula unit. These results are important in view of reports which\nclaim that $\\zeta$-Fe$_2$N undergoes an AFM transition below 10K and others\nwhich do not observe any magnetic transition up to 4.2K. We argue that the\nexperimental results of AFM transition below 10K are inconclusive and we\npropose the presence of competing FM and AFM superexchange interactions between\nFe sites mediated by nitrogen atoms, which are consistent with\nGoodenough-Kanamori-Anderson rules. We find that the anti-ferromagnetically\ncoupled Fe sites are outnumbered by ferromagnetically coupled Fe sites leading\nto a stable FM ground state. A Stoner analysis of the results also supports our\nclaim of a FM ground state."
    },
    {
        "anchor": "Design guidelines for two-dimensional transition metal dichalcogenide\n  alloys: Two-dimensional (2D) materials and Transition Metal Dichalcogenides (TMD) in\nparticular are at the forefront of nanotechnology. To tailor properties for\nengineering applications, alloying strategies used for bulk metals in the last\ncentury need to be extended to this novel class of materials. Here we present a\nsystematic analysis of the phase behaviour of substitutional 2D alloys in the\nTMD family on both the metal and chalcogenide site. The phase behaviour is\nquantified in terms of a metastability metric and benchmarked against\nsystematic computational screening of configurational energy landscapes. The\nresulting Pettifor maps can be used to identify broad trends across chemical\nspaces and as starting point for setting up rational search strategies in phase\nspace, thus allowing for targeted computational analysis of properties on\nlikely thermodynamically stable compounds. The results presented here also\nconstitute a useful guideline for synthesis of binary metal 2D TMDs alloys via\na range of synthesis techniques.",
        "positive": "Investigation of Ga interstitial and vacancy diffusion in\n  $\u03b2$-Ga$_2$O$_3$ via split defects: a direct approach via master diffusion\n  equations: The low symmetry of monoclinic $\\beta$-Ga$_2$O$_3$ leads to elaborate\nintrinsic defects, such as Ga vacancies split amongst multiple lattice sites.\nThese defects contribute to fast, anisotropic Ga diffusion, yet their\ncomplexity makes it challenging to understand dominant diffusion mechanisms.\nHere, we predict the 3D diffusivity tensors for Ga interstitials\n(Ga${_i^{3+}}$) and vacancies (V${_{Ga}^{3-}}$) via first principles and direct\nsolution of the master diffusion equations. We first explore the maximum extent\nof configurationally complex ''$N$-split'' Ga interstitials and vacancies. With\ndominant low-energy defects identified, we enumerate all possible elementary\nhops connecting defect configurations to each other, including interstitialcy\nhops. Hopping barriers are obtained from nudged elastic band simulations.\nFinally, the comprehensive sets of (i) defect configurations and their energies\nand (ii) the hopping barriers that connect them are used to construct the\nmaster diffusion equations for both Ga${_i^{3+}}$ and V${_{Ga}^{3-}}$. The\nsolution to these equations yields the Onsager transport coefficients, i.e. the\ncomponents of the 3D diffusivity tensors $D_{{Ga}_i}$ and $D_{V_{Ga}}$ for\nGa${_i^{3+}}$ and V${_{Ga}^{3-}}$, respectively. It further reveals the active\ndiffusion paths along all crystallographic directions. We find that both\nGa${_i^{3+}}$ and V${_{{Ga}}^{3-}}$ diffusion are fastest along the $c$-axis,\ndue to 3-split defects that bridge neighboring unit cells along the $c$-axis\nand divert diffusing species around high-energy bottlenecks. Although isolated\nGa${_i^{3+}}$ diffuse faster than isolated V${_{Ga}^{3-}}$, self-diffusion of\nGa is predominantly mediated by V$_{Ga}^{3-}$ due to the higher V$_{Ga}^{3-}$\ndefect concentration under most thermodynamic environments."
    },
    {
        "anchor": "The response of linear inhomogeneous systems to coupled fields: Bounds\n  and perturbation expansions: We consider the response of a multicomponent body to $n$ fields, such as\nelectric fields, magnetic fields, temperature gradients, concentration\ngradients, etc., where each component, which is possibly anisotropic, may cross\ncouple the various fields with different fluxes, such as electrical currents,\nelectrical displacement currents, magnetic induction fields, energy fluxes,\nparticle fluxes, etc. We obtain the form of the perturbation expansions of the\nfields and response tensor in powers of matrices which measure the difference\nbetween each component tensor and a homogeneous reference tensor ${\\bf L}_0$.\nFor the case of a statistically homogeneous or periodic composite the expansion\ncoefficients can be expressed in terms of positive semidefinite normalization\nmatrices alternating with positive semidefinite weight matrices, which at each\ngiven level sum to the identity matrix. In an appropriate basis the projection\noperators onto the relevant subspaces can be expressed in block tridiagonal\nform, where the blocks are functions of these weight and normalization\nmatrices. This leads to continued fraction expansions for the effective tensor,\nand by truncating the continued fraction at successive levels one obtains a\nnested sequence of bounds on the effective tensor incorporating successively\nmore weight and normalization matrices. The weight matrices and normalization\nmatrices can be calculated from the series expansions of the fields which solve\nthe conductivity problem alone, without any couplings to other fields, and then\nthey can be used to obtain the solution for the fields and effective tensor in\ncoupled field problems in composites.",
        "positive": "Sample Size Effects on the Transport Characteristics of Mesoscopic\n  Graphite Samples: In this work we investigated correlations between the internal microstructure\nand sample size (lateral as well as thickness) of mesoscopic, tens of nanometer\nthick graphite (multigraphene) samples and the temperature $(T)$ and field\n$(B)$ dependence of their electrical resistivity $\\rho(T,B)$. Low energy\ntransmission electron microscopy reveals that the original highly oriented\npyrolytic graphite material -- from which the multigraphene samples were\nobtained by exfoliation -- is composed of a stack of $\\sim 50 $nm thick and\nmicrometer long crystalline regions separated by interfaces running parallel to\nthe graphene planes. We found a qualitative and quantitative change in the\nbehavior of $\\rho(T,B)$ upon thickness of the multigraphene samples, indicating\nthat their internal microstructure is important.} {The overall results indicate\nthat the metallic-like behavior of $\\rho(T)$ at zero field measured for bulk\ngraphite samples is not intrinsic of ideal graphite. The results suggest that\nthe interfaces between crystalline regions may be responsible for the\nsuperconducting-like properties observed in graphite. Our transport\nmeasurements also show that reducing the sample lateral size as well as the\nlength between voltage electrodes decreases the magnetoresistance, in agreement\nwith recently published results. The magnetoresistance of the multigraphene\nsamples shows a scaling of the form ($(R(B) - R(0))/R(0))/T^\\alpha = f(B/T)$\nwith a sample dependent exponent $\\alpha \\sim 1$, which applies in the whole\ntemperature 2 K $\\le T \\le 270$K and magnetic field range $B \\le 8 $T."
    },
    {
        "anchor": "Design principles for the energy level tuning in donor/acceptor\n  conjugated polymers: To identify reliable molecular design principles for energy level tuning in\ndonor/acceptor conjugated polymers (CPs), we studied the governing factors by\nmeans of ab initio calculations based on density-functional theory (DFT). We\ninvestigated a series of CPs in which we independently and systematically\nvaried the electron withdrawing power of the acceptor unit and the electron\ndonating power of the donor unit, while maintaining the same conjugated chain\nconformation. We observed that the introduction of a stronger acceptor unit,\nwhile keeping the same donor unit in the CP, lowers the LUMO level, but leaves\nthe HOMO level almost unchanged. Conversely, enhancing the strength of the\ndonor unit for the same acceptor unit raises the HOMO level, while maintaining\nthe LUMO level. We identified strong correlations between the frontier orbital\nenergy levels and the degree of orbital localization, which depends on the\nelectron donating or withdrawing power of the molecular groups carrying the\norbitals. Moreover, the HOMO/LUMO gap of the CP is directly proportional to the\ncharge transfer between donating and accepting units, which provides a robust\ndesign criterion for CPs.",
        "positive": "Structural, electronic and magnetic properties of the Manganese\n  telluride layers AMnTe2 (A=K, Rb, Cs) from first-principles calculations: Using first-principles electronic structure calculations based on density\nfunctional theory (DFT), we investigate the structural, electronic and magnetic\nproperties of the layered ternary manganese tellurides: AMnTe2 (A = K, Rb, and\nCs). Calculations are accomplished within the full-potential linearized\naugmented plane wave (FP-LAPW) using the generalized gradient approximation GGA\nformalism for the exchange correlation term. We have treated all ferromagnetic,\nantiferromagnetic and non-magnetic phases and found that the ferromagnetic is\nthe ground-state for all studied compounds. Moreover, all three compounds under\nstudy are half-metals with a total spin magnetic per formula unit of 4 mu_B\nwhich is mainly localized at the Mn atoms. We express for these compounds a new\nversion of the Slater-Pauling rule and discuss in detail the origin of the\nminority-spin gap. Finally, we have also calculated some other relevant\nquantities such as the bulk modulus B, the pressure derivative B', the virtual\nsemiconducting gap Eg, and the half-metallic gap E_HM."
    },
    {
        "anchor": "An optimized interatomic potential for silicon and its application to\n  thermal stability of silicene: An optimized interatomic potential has been constructed for silicon using a\nmodified Tersoff model. The potential reproduces a wide range of properties of\nSi and improves over existing potentials with respect to point defect\nstructures and energies, surface energies and reconstructions, thermal\nexpansion, melting temperature and other properties. The proposed potential is\ncompared with three other potentials from the literature. The potentials\ndemonstrate reasonable agreement with first-principles binding energies of\nsmall Si clusters as well as single-layer and bilayer silicenes. The four\npotentials are used to evaluate the thermal stability of free-standing\nsilicenes in the form of nano-ribbons, nano-flakes and nano-tubes. While\nsingle-layer silicene is mechanically stable at zero Kelvin, it is predicted to\nbecome unstable and collapse at room temperature. By contrast, the bilayer\nsilicene demonstrates a larger bending rigidity and remains stable at and even\nabove room temperature. The results suggest that bilayer silicene might exist\nin a free-standing form at ambient conditions.",
        "positive": "Spin-glass behavior in single crystals of hetero-metallic magnetic\n  warwickites $MgFeBO_4$, $Mg_{0.5}Co_{0.5}FeBO_4$, and $CoFeBO_4$: Magnetic properties of heterometallic warwickites $MgFeBO_4$,\n$Mg_{0.5}Co_{0.5}FeBO_4$, and $CoFeBO_4$ are presented, highlighting the effect\nof Co substitution on the magnetic properties of these compounds. The analysis\nof magnetization and heat capacity data has shown that these compounds exhibit\na spin-glass transition below $T_{SG}$=10, 20 and 22 K, respectively. Using\nzero field ac susceptibility as entanglement witness we find that the low\ndimensional magnetic behavior above $T_{SG}$ show quantum entanglement behavior\n$\\chi(T)\\varpropto T^{-\\alpha(T)}$ up to $T_E$ = 130K. The $\\alpha$ parameters\nhave been deduced as a function of temperature and Co, indicating the existence\nof random singlet phase in this temperature region. Above $T_E$ the\nparamagnetism is interpreted in terms of non-entangled spins giving rise to\nCurie-Weiss paramagnetism. The different intra- and inter-ribbon exchange\ninteraction pathways have been calculated within a simple indirect coupling\nmodel. It is determined that the triangular motifs in the warwickite structure,\ntogether with the competing interactions, induce frustration. The spin-glass\ncharacter is explained in terms of the substitutional disorder of the Mg, Fe\nand Co atoms at the two available crystallographic sites, and the frustration\ninduced by the competing interactions. The Co substitution induces uniaxial\nanisotropy along the b axis, increases the absolute magnetization and increases\nthe spin-glass freezing temperature. The entanglement behavior is supported in\nthe intermediate phase irrespective of the introduction of anisotropy by the Co\nsubstitution."
    },
    {
        "anchor": "Clustering Kinetics of Granular Media in Three Dimensions: Three-dimensional molecular dynamics simulations of dissipative particles (~\n10^6) are carried out for studying the clustering kinetics of granular media\nduring cooling. The inter-connected high particle density regions are\nidentified, showing tube-like structures. The energy decay rates as functions\nof the particle density and the restitution coefficient are obtained. It is\nfound that the probability density function of the particle density obeys an\nexponential distribution at late stages. Both the fluctuation of density and\nthe mean cluster size of the particle density have power law relations against\ntime during the inelastic coalescing process.",
        "positive": "Modeling the viscoelastoplastic response of amorphous glassy polymers: Constitutive equations are derived for the viscoelastoplastic response of\namorphous glassy polymers at isothermal loading with small strains. A polymer\nis treated as an ensemble of cooperatively relaxing regions (CRR) which\nrearrange at random times as they are thermally agitated. Rearrangement of CRRs\nreflects the viscoelastic response of the bulk medium. At low stresses, CRRs\nare connected with each other, which implies that the macro-strain in a\nspecimen coincides with micro-strains in individual relaxing regions. When the\naverage stress exceeds some threshold level, links between CRRs break and\nrelaxing domains begin to slide one with respect to another. Sliding of\nmicro-domains is associated with the viscoplastic behavior of polymers. Kinetic\nequations are proposed for viscoplastic strains and for the evolution of the\nthreshold stress. These equations are validated by comparison with experimental\ndata in tensile relaxation tests and in tests with constant strain rates. Fair\nagreement is demonstrated between results of numerical simulation and\nobservations for a polyurethane resin and poly(methyl methacrylate)."
    },
    {
        "anchor": "Glass Transition of the Phase Change Material AIST and its Impact on\n  Crystallization: Engineering phase change materials (PCM) to realize superior data storage\ndevices requires a detailed understanding of crystallization kinetics and its\ntemperature dependence. The temperature dependence of crystallization differs\ndistinctly between crystallizing from the glassy phase and the undercooled\nliquid (UCL). Hence, knowing the phase from which crystallization occurs is\nnecessary for predicting the switching ability. Here, we measure the glassy\ndynamics and crystallization kinetics using calorimetry for heating rates\nspanning over six orders of magnitude. Our results show that the prominent PCM\n(Ag,In)-doped Sb2Te (AIST) exhibits a change from crystallizing from the glassy\nphase to crystallizing from the UCL at a critical heating rate of 5,000 K/s.\nAbove the glass transition, the activation energy of crystallization changes\ndrastically enabling rapid crystallization at elevated temperatures.",
        "positive": "Magnetocapacitance as a sensitive probe of magnetostructural changes in\n  NiCr$_2$O$_4$: The spinel NiCr$_2$O$_4$ is characterized using dielectric and high magnetic\nfield measurements. The trends in the magnetodielectric response fall into\nthree clear temperature regimes corresponding to known magnetic and structural\ntransitions. Above 65\\,K, weak magnetic field dependence of the dielectric\nconstant is observed with no hysteresis. When 30\\,K\\,$\\leq\\,T\\,\\leq$\\,65\\,K, a\nstrong dependence of the dielectric constant on the magnetic field is observed\nand hysteresis develops resulting in so called butterfly loops. Below 30\\,K,\nmagnetodielectric hysteresis is enhanced. Magnetodielectric hysteresis mirrors\nmagnetic hysteresis suggesting that spin-spin interactions are the mechanism\nfor the magnetoelectric effect in NiCr$_2$O$_4$. At high fields however, the\nmagnetization continues to increase while the dielectric constant saturates.\nMagnetodielectric measurements of NiCr$_2$O$_4$ suggest an additional,\npreviously unobserved transition at 20\\,K. Subtle changes in magnetism and\nstructure suggest that this 20\\,K anomaly corresponds to the completion of\nferrimagnetic ordering and the spin driven structural distortion. We\ndemonstrate that magnetocapacitance is a sensitive probe of magnetostructural\ndistortion."
    },
    {
        "anchor": "Surface roughness evolution in a solid-on-solid model of epitaxial\n  growth: The paper presents results from kinetic Monte Carlo simulations of kinetic\nsurface roughening using an important and experimentally relevant model of\nepitaxial growth -- the solid-on-solid model with Arrhenius dynamics. A\nrestriction on diffusing adatoms is included allowing hopping down only at\nsteps of height one monolayer in order to avoid possibly unrealistic events of\njumping from arbitrarily high steps. Simulation results and precise analytic\nexpressions representing the time evolution of surface roughness do not depend\non the substrate size and clearly put forward the conclusion that for any basic\nset of parameters the model approaches in asymptotic limit the usual random\ndeposition process with growth exponent $\\beta=1/2$. At high temperatures, it\nis preceded by a long transient regime characterized by a smooth surface\ncovered with porous pillars and described by a power law with $\\beta=3/4$.",
        "positive": "Wave vector star channel and star channel group in the reciprocal\n  lattice space of crystal: In the paper, a new method determining the wave vector star channel in the\nreciprocal lattice space of crystal in the light of the translational symmetry\nbreaking is proposed, and, in order to consider the phase transitions according\nto the wave vector star channel, the conception of wave vector star channel\ngroup is adopted. By this method, it is revealed that the phase transitions in\ncrystal are induced not by any arbitrary combinations of arms of the given\nstar, but by the selected combinations of arms which are satisfied by symmetry\nof the parent phase. The wave vector star channel group is defined as the set\nof elements of space group leaving the wave vector star channel invariant. We\nshow that the conception of wave vector star channel group can be efficiently\nused in studying the translational symmetry breaking related to all the\nLifshitz wave vector stars of 230 space groups."
    },
    {
        "anchor": "Precursor recommendation for inorganic synthesis by machine learning\n  materials similarity from scientific literature: Synthesis prediction is a key accelerator for the rapid design of advanced\nmaterials. However, determining synthesis variables such as the choice of\nprecursor materials is challenging for inorganic materials because the sequence\nof reactions during heating is not well understood. In this work, we use a\nknowledge base of 29,900 solid-state synthesis recipes, text-mined from the\nscientific literature, to automatically learn which precursors to recommend for\nthe synthesis of a novel target material. The data-driven approach learns\nchemical similarity of materials and refers the synthesis of a new target to\nprecedent synthesis procedures of similar materials, mimicking human synthesis\ndesign. When proposing five precursor sets for each of 2,654 unseen test target\nmaterials, the recommendation strategy achieves a success rate of at least 82%.\nOur approach captures decades of heuristic synthesis data in a mathematical\nform, making it accessible for use in recommendation engines and autonomous\nlaboratories.",
        "positive": "Thermal conductivity of a new carbon nanotube analogue: the diamond\n  nanothread: Based on the non-equilibrium molecular dynamics simulations, we have studied\nthe thermal conductivities of a novel ultra-thin one-dimensional carbon\nnanomaterial - diamond nanothread (DNT). Unlike single-wall carbon nanotube\n(CNT), the existence of the Stone-Wales transformations in DNT endows it with\nricher thermal transport characteristics. There is a transition from\nwave-dominated to particle-dominated transport region, which depends on the\nlength of poly-benzene rings. However, independent of the transport region,\nstrong length dependence in thermal conductivity is observed in DNTs with\ndifferent lengths of poly-benzene ring. The distinctive SW characteristic in\nDNT provides more degrees of freedom to tune the thermal conductivity not found\nin the homogeneous structure of CNT. Therefore, DNT is an ideal platform to\ninvestigate various thermal transport mechanisms at the nanoscale. Its high\ntunability raises the potential to design DNTs for different applications, such\nas thermal connection and temperature management."
    },
    {
        "anchor": "Substituent-Controlled Reversible Switching of Charge-Injection-Barrier\n  Heights at Metal/Organic-Semiconductor Contacts Modified with Disordered\n  Molecular Monolayers: Electrically stimulated switching of a charge injection barrier at the\ninterface between an organic semiconductor and an electrode modified with a\ndisordered monolayer (DM) is studied by using various benzenethiol derivatives\nas DM molecules. The switching behavior is induced by a structural change in\nthe DM molecules, and is manifested as a reversible inversion of the polarity\nof DM-modified Au electrode/rubrene/DM-modified Au electrode diodes. The\nswitching direction is found to be dominantly determined by the push-back\neffect of the thiol bonding group, while the terminal group modulates the\nswitching strength. A device with 1,2-benzenedithiol DMs exhibited the highest\nswitching ratios of 20, 100, and 1000 for the switching voltages of 3, 5, and 7\nV, respectively. A variation in the tilt angle of benzenethiol DMs owing to the\napplication of 7 V is estimated to be smaller than 23.6 degrees by model\ncalculations. This study offers an understanding for obtaining highly stable\noperations of organic electronic devices, especially with molecular\nmodification layers.",
        "positive": "Hopping Transport through Defect-induced Localized States in Molybdenum\n  Disulfide: Molybdenum disulfide is a novel two-dimensional semiconductor with potential\napplications in electronic and optoelectronic devices. However, the nature of\ncharge transport in back-gated devices still remains elusive as they show much\nlower mobility than theoretical calculations and native n-type doping. Here we\nreport transport study in few-layer molybdenum disulfide, together with\ntransmission electron microscopy and density functional theory. We provide\ndirect evidence that sulfur vacancies exist in molybdenum disulfide,\nintroducing localized donor states inside the bandgap. Under low carrier\ndensities, the transport exhibits nearest-neighbor hopping at high temperatures\nand variable-range hopping at low temperatures, which can be well explained\nunder Mott formalism. We suggest that the low-carrier-density transport is\ndominated by hopping via these localized gap states. Our study reveals the\nimportant role of short-range surface defects in tailoring the properties and\ndevice applications of molybdenum disulfide."
    },
    {
        "anchor": "Ferroelectricity in the Dion-Jacobson CsBiNb$_2$O$_7$ from first\n  principles: We have studied ferroelectricity in Dion-Jacobson CsBiNb$_2$O$_7$ from first\nprinciples. Using group-theoretical analysis and first-principles density\nfunctional calculations of the total energy and phonons, we perform a\nsystematic study of the energy surface around a paraelectric prototypic phase.\nOur results suggest that CsBiNb$_2$O$_7$ is a ferroelectric with a polarization\nof P$_s$=40$\\mu$C cm$^{-2}$. We propose further experiments to clarify this\npoint.",
        "positive": "Epitaxial growth of bilayer Bi(110) on two-dimensional ferromagnetic\n  Fe3GeTe2: Heterostructures of two-dimensional (2D) layered materials with selective\ncompositions play an important role in creating novel functionalities.\nEffective interface coupling between 2D ferromagnet and electronic materials\nwould enable the generation of exotic physical phenomena caused by intrinsic\nsymmetry breaking and proximity effect at interfaces. Here, epitaxial growth of\nbilayer Bi(110) on 2D ferromagnetic Fe3GeTe2 (FGT) with large magnetic\nanisotropy has been reported. Bilayer Bi(110) islands are found to extend along\nfixed lattice directions of FGT. The six preferred orientations could be\ndivided into two groups of three-fold symmetry axes with the difference\napproximately to 26{\\deg}. Moreover, dI/dV measurements confirm the existence\nof interface coupling between bilayer Bi(110) and FGT. A variation of the\nenergy gap at the edges of bilayer Bi(110) is also observed which is modulated\nby the interface coupling strengths associated with its buckled atomic\nstructure. This system provides a good platform for further study of the exotic\nelectronic properties of epitaxial Bi(110) on 2D ferromagnetic substrate and\npromotes potential applications in the field of spin devices."
    },
    {
        "anchor": "Field distributions and effective-medium approximation for weakly\n  nonlinear media: An effective-medium theory is proposed for random weakly nonlinear dielectric\nmedia. It is based on a new gaussian approximation for the probability\ndistributions of the electric field in each component of a multi-phase\ncomposite. These distributions are computed to linear order from a\nBruggeman-like self-consistent formula. The resulting effective-medium formula\nfor the nonlinear medium reduces to Bruggeman's in the linear case. It is exact\nup to second order in a weak-disorder expansion, and close to the exact result\nin the dilute limit (in particular, it is exact for d=1 and d=infinity. In a\nhigh contrast situation, the noise exponents are kappa=kappa'=0 near the\npercolation threshold. Numerical results are provided for different weak\nnonlinearities.",
        "positive": "Room temperature spin filtering in epitaxial cobalt-ferrite tunnel\n  barriers: We report direct experimental evidence of room temperature spin filtering in\nmagnetic tunnel junctions (MTJs) containing CoFe2O4 tunnel barriers via\ntunneling magnetoresistance (TMR) measurements.\nPt(111)/CoFe2O4(111)/gamma-Al2O3(111)/Co(0001) fully epitaxial MTJs were grown\nin order to obtain a high quality system, capable of functioning at room\ntemperature. Spin polarized transport measurements reveal significant TMR\nvalues of -18% at 2 K and -3% at 290 K. In addition, the TMR ratio follows a\nunique bias voltage dependence that has been theoretically predicted to be the\nsignature of spin filtering in MTJs containing magnetic barriers. CoFe2O4\ntunnel barriers therefore provide a model system to investigate spin filtering\nin a wide range of temperatures."
    },
    {
        "anchor": "Motion of water monomers reveals a kinetic barrier to ice nucleation on\n  graphene: The interfacial behaviour of water remains a central question to fields as\ndiverse as protein folding, friction and ice formation[1,2]. While the\nstructural and dynamical properties of water at interfaces differ strongly from\nthose in the bulk, major gaps in our knowledge at the molecular level still\nprevent us from understanding these ubiquitous chemical processes. Information\nconcerning the microscopic motion of water comes mostly from computational\nsimulation[3,4] but the dynamics of molecules, on the atomic scale, is largely\nunexplored by experiment. Here we present experimental results combined with ab\ninitio calculations to provide a detailed insight into the behaviour of water\nmonomers on a graphene surface. We show that motion occurs by activated hopping\non the graphene lattice. The dynamics of water diffusion displays remarkably\nstrong signatures of cooperative behaviour due to repulsive forces between the\nmonomers. The repulsive forces enhance the monomer lifetime ($t_m \\approx 3$ s\nat $T_S = 125$ K) in a $\\textit{free-gas}$ phase that precedes the nucleation\nof ice islands and, in turn, provides the opportunity for our experiments to be\nperformed. Our results give a unique molecular perspective of barriers to ice\nnucleation on material surfaces, providing new routes to understand and\npotentially control the more general process of ice formation.",
        "positive": "Spin canting in nonlinear terahertz magnon dynamics revealed by\n  magnetorefractive probing in orthoferrite: We excite the spin precession in rare-earth orthoferrite YFeO3 by the\nmagnetic field of intense terahertz pulse and probe its dynamics by transient\nabsorption change in the near infrared. The observed waveforms contain\nquasi-ferromagnetic-mode magnon oscillation and its second harmonics with a\ncomparably strong amplitude. The result can be explained by dielectric function\nderived from magnetorefractive Hamiltonian. We reveal that the strong second\nharmonic signal microscopically originates from novel dynamics of the\nquasi-ferromagnetic mode magnon at nonlinear regime, wherein spin canting angle\nperiodically oscillates."
    },
    {
        "anchor": "Stable biexcitons in two-dimensional metal-halide perovskites with\n  strong dynamic lattice disorder: With strongly bound and stable excitons at room temperature, single-layer,\ntwo-dimensional organic-inorganic hybrid perovskites are viable semiconductors\nfor light-emitting quantum optoelectronics applications. In such a\ntechnological context, it is imperative to comprehensively explore all the\nfactors --- chemical, electronic and structural --- that govern strong\nmulti-exciton correlations. Here, by means of two-dimensional coherent\nspectroscopy, we examine excitonic many-body effects in pure, single-layer\n(PEA)$_2$PbI$_4$ (PEA = phenylethylammonium). We determine the binding energy\nof biexcitons --- correlated two-electron, two-hole quasiparticles --- to be\n$44 \\pm 5$\\,meV at room temperature. The extraordinarily high values are\nsimilar to those reported in other strongly excitonic two-dimensional materials\nsuch as transition-metal dichalchogenides. Importantly, we show that this\nbinding energy increases by $\\sim25$\\% upon cooling to 5\\,K. Our work\nhighlights the importance of multi-exciton correlations in this class of\ntechnologically promising, solution-processable materials, in spite of the\nstrong effects of lattice fluctuations and dynamic disorder.",
        "positive": "Transformational process zone emerging at the tip of a propagating crack: Process zone at the tip of a propagating crack engendered by the\nstress-induced local phase transition of the second order is studied\ntheoretically. We show that the zone can only exist within a certain domain of\nthe phase diagram at one side of the phase transition line depending upon the\nsign of the striction constant. We obtain the boundary of this domain and\nestablish its dependence upon the crack velocity. We show the existence of a\ncritical crack velocity above which the zone cannot exist. We report the\novercritical solution for the order parameter describing the incipient process\nzone, while far from the bifurcation point we solve the problem numerically."
    },
    {
        "anchor": "Giant Enhancement of Surface Second Harmonic Generation in BaTiO_3 due\n  to Photorefractive Surface Wave Excitation: We report observation of strongly enhanced surface SHG in BaTiO_3 due to\nexcitation of a photorefractive surface electromagnetic wave. Surface SH\nintensity may reach 10^{-2} of the incident fundamental light intensity.\nAngular, crystal orientation and polarization dependencies of this SHG are\npresented. Possible applications of this effect in nonlinear surface\nspectroscopy are discussed.",
        "positive": "Homogeneous ice nucleation in an ab initio machine learning model of\n  water: Molecular simulations have provided valuable insight into the microscopic\nmechanisms underlying homogeneous ice nucleation. While empirical models have\nbeen used extensively to study this phenomenon, simulations based on\nfirst-principles calculations have so far proven prohibitively expensive. Here,\nwe circumvent this difficulty by using an efficient machine learning model\ntrained on density-functional theory (DFT) energies and forces. We compute\nnucleation rates at atmospheric pressure, over a broad range of supercoolings,\nusing the seeding technique and systems of up to hundreds of thousands of atoms\nsimulated with ab initio accuracy. The key quantity provided by the seeding\ntechnique is the size of the critical cluster (i.e., a size such that the\ncluster has equal probabilities of growing or melting at the given\nsupersaturation) which is used together with the equations of classical\nnucleation theory to compute nucleation rates. We find that nucleation rates\nfor our model at moderate supercoolings are in good agreement with experimental\nmeasurements within the error of our calculation. We also study the impact of\nproperties such as the thermodynamic driving force, interfacial free energy,\nand stacking disorder on the calculated rates."
    },
    {
        "anchor": "Reversible phase transformation and doubly-charged anions at the surface\n  of simple cubic RbC60: The simple cubic phase of a RbC60 thin film has been studied using\nphotoelectron spectroscopy. The simple cubic-to-dimer transition is found to be\nreversible at the film surface. A sharp Fermi edge is observed and a lower\nlimit of 0.5 eV is found for the surface Hubbard U, pointing to a\nstrongly-correlated metallic character of thin-film simple cubic RbC60. A\nmolecular charge state is identified in the valence band and core level\nphotoemission spectra which arises from C602- anions and contributes to the\nspectral intensity at the Fermi level.",
        "positive": "Stress in ordered systems: Ginzburg-Landau type density field theory: We present a theoretical method for deriving the stress tensor and elastic\nresponse of ordered systems within a Ginzburg-Landau type density field theory\nin the linear regime. This is based on spatially coarse graining the\nmicroscopic stress which is determined by the variation of a free energy with\nrespect to mass displacements. We find simple expressions for the stress tensor\nfor phase field crystal (PFC) models for different crystal symmetries in two\nand three dimensions. Using tetradic product sums of reciprocal lattice\nvectors, we calculate elastic constants and show that they are directly related\nto the symmetries of the reciprocal lattices. We also show that except for bcc\nlattices, there are regions of model parameters for which the elastic response\nis isotropic. The predicted elastic stress-strain curves are verified by\nnumerical strain-controlled bulk and shear deformations. Since the method is\nindependent of a reference state, it extends also to defected crystals. We\nexemplify this by considering an edge and screw dislocation in the simple cubic\nlattice."
    },
    {
        "anchor": "Tailoring the interfacial magnetic interaction in epitaxial\n  La$_{0.7}$Sr$_{0.3}$MnO$_3$/Sm$_{0.5}$Ca$_{0.5}$MnO$_3$ heterostructures: Interface engineering in complex oxide heterostructures has developed into a\nflourishing field as various intriguing physical phenomena can be demonstrated\nwhich are otherwise absent in their constituent bulk compounds. Here we present\nLa$_{0.7}$Sr$_{0.3}$MnO$_3$ (LSMO) / Sm$_{0.5}$Ca$_{0.5}$MnO$_3$ (SCMO) based\nheterostructures showcasing the dominance of antiferromagnetic interaction with\nincreasing interfaces. In particular, we demonstrate that exchange bias can be\ntuned by increasing the number of interfaces; while, on the other hand,\nelectronic phase separation can be mimicked by creating epitaxial multilayers\nof such robust charge ordered antiferromagnetic (CO-AF) and ferromagnetic (FM)\nmanganites with increased AF nature, which otherwise would require\nintrinsically disordered mixed phase materials. The origin of these phenomena\nis discussed in terms of magnetic interactions between the interfacial layers\nof the LSMO/SCMO. A theoretical model has been utilized to account for the\nexperimentally observed magnetization curves in order to draw out the complex\ninterplay between FM and AF spins at interfaces with the onset of charge\nordering.",
        "positive": "Localized heating in nanoscale Pt constrictions measured using blackbody\n  radiation emission: Using thermal emission microscopy, we investigate heating in Pt nanowires\nbefore and during electromigration. The wires are observed to reach\ntemperatures in excess of 1000 K. This is beyond the thermal decomposition\nthreshold for many organic molecules of interest for single molecule\nmeasurements with electromigrated nanogaps. Blackbody spectra of the hot Pt\nwires are measured and found to agree well with finite element modeling\nsimulations of the electrical and thermal transport."
    },
    {
        "anchor": "Structural Stability and Optoelectronic Properties of Tetragonal MAPbI3\n  under Strain: In recent years, organic-inorganic hybrid perovskites have attracted wide\nattention due to their excellent optoelectronic properties in the application\nof optoelectronic devices. In the manufacturing process of perovskite solar\ncells, perovskite films inevitably have residual stress caused by\nnon-stoichiometry components and the external load. However, their effects on\nthe structural stability and photovoltaic performance of perovskite solar cells\nare still not clear. In this work, we investigated the effects of external\nstrain on the structural stability and optoelectronic properties of tetragonal\nMAPbI3 by using the first-principles calculations. We found that the migration\nbarrier of I- ion increases in the presence of compressive strain and decreases\nwith tensile strain, indicating that the compressive strain can enhance the\nstructural stability of halide perovskites. In addition, the light absorption\nand electronic properties of MAPbI3 under compressive strain are also improved.\nThe variations of the band gap under triaxial and biaxial strains are\nconsistent within a certain range of strain, resulting from the fact that the\nband edge positions are mainly influenced by the Pb-I bond in the equatorial\nplane. Our results provide useful guidance for realizing the commercial\napplications of MAPbI3-based perovskite solar cells.",
        "positive": "Magnetic Frustration in a Zeolite: Zeolites are so well known in real world applications and after decades of\nscientific study that they hardly need any intro-duction: their importance in\nchemistry cannot be overemphasized. Here we add to the remarkable properties\nthat they dis-play by reporting our discovery that the simplest zeolite,\nsodalite, when doped with Cr3+ in the \\b{eta}-cage, is a frustrated magnet.\nSoft X-ray absorption spectroscopy and magnetic measurements reveal that the Cr\npresent is Cr(III). Cr(III), with its isotropic 3d3 valence electron\nconfiguration, is well-known as the basis for many geometrically frustrated\nmagnets, but it is especially surprising that a material like the Ca8Al12Cr2O29\nzeolite is a frustrated magnet. This finding illustrates the value of exploring\nthe properties of even well-known materials families."
    },
    {
        "anchor": "Anomalous thickness-dependent electrical conductivity in van der Waals\n  layered transition metal halide, Nb_3Cl_8: Understanding the electronic transport properties of layered, van der Waals\ntransition metal halides (TMHs) and chalcogenides is a highly active research\ntopic today. Of particular interest is the evolution of those properties with\nchanging thickness as the 2D limit is approached. Here, we present the\nelectrical conductivity of exfoliated single crystals of the TMH, cluster\nmagnet, Nb3Cl8, over a wide range of thicknesses both with and without\nhexagonal boron nitride (hBN) encapsulation. The conductivity is found to\nincrease by more than three orders of magnitude when the thickness is decreased\nfrom 280 {\\mu}m to 5 nm, at 300 K. At low temperatures and below ~50 nm, the\nconductance becomes thickness independent, implying surface conduction is\ndominating. Temperature dependent conductivity measurements indicate Nb3Cl8 is\nan insulator, however the effective activation energy decreases from a bulk\nvalue of 310 meV to 140 meV by 5nm. X-ray photoelectron spectroscopy (XPS)\nshows mild surface oxidation in devices without hBN capping, however, no\nsignificant difference in transport is observed when compared to the capped\ndevices, implying the thickness dependent transport behavior is intrinsic to\nthe material. A conduction mechanism comprised of a higher conductivity surface\nchannel in parallel with a lower conductivity interlayer channel is discussed.",
        "positive": "Mixed Dimensionality of Confined Conducting Electrons in the Surface\n  Region of SrTiO$_{3}$: Using angle-resolved photoemission spectroscopy, we show that the\nrecently-discovered surface state on SrTiO$_{3}$ consists of non-degenerate\n$t_{2g}$ states with different dimensional characters. While the $d_{xy}$ bands\nhave quasi-2D dispersions with weak $k_{z}$ dependence, the lifted\n$d_{xz}$/$d_{yz}$ bands show 3D dispersions that differ significantly from bulk\nexpectations and signal that electrons associated with those orbitals permeate\nthe near-surface region. Like their more 2D counterparts, the size and\ncharacter of the $d_{xz}$/$d_{yz}$ Fermi surface components are essentially the\nsame for different sample preparations. Irradiating SrTiO$_{3}$ in ultrahigh\nvacuum is one method observed so far to induce the \"universal\" surface metallic\nstate. We reveal that during this process, changes in the oxygen valence band\nspectral weight that coincide with the emergence of surface conductivity are\ndisproportionate to any change in the total intensity of the O $1s$ core level\nspectrum. This signifies that the formation of the metallic surface goes beyond\na straightforward chemical doping scenario and occurs in conjunction with\nprofound changes in the initial states and/or spatial distribution of\nnear-$E_{F}$ electrons in the surface region."
    },
    {
        "anchor": "STM contrast inversion of the Fe(110) surface: We extend the orbital-dependent electron tunneling model implemented within\nthe three-dimensional (3D) Wentzel-Kramers-Brillouin (WKB) atom-superposition\napproach to simulate spin-polarized scanning tunneling microscopy (SP-STM)\nabove magnetic surfaces. The tunneling model is based on the electronic\nstructure data of the magnetic tip and surface obtained from first principles.\nApplying our method, we analyze the orbital contributions to the tunneling\ncurrent, and study the nature of atomic contrast reversals occurring on\nconstant-current SP-STM images above the Fe(110) surface. We find an interplay\nof orbital-dependent tunneling and spin-polarization effects responsible for\nthe contrast inversion, and we discuss its dependence on the bias voltage, on\nthe tip-sample distance, and on the tip orbital composition.",
        "positive": "The structural, magnetic and optical properties of TMn@(ZnO)42 (TM = Fe,\n  Co and Ni) hetero-nanostructure: The magnetic transition-metal (TM) @ oxide nanoparticles have been of great\ninterest due to their wide range of applications, from medical sensors in\nmagnetic resonance imaging to photo-catalysis. Although several studies on\nsmall clusters of TM@oxide have been reported, the understanding of the\nphysical electronic properties of TMn@(ZnO)42 is far from sufficient. In this\nwork, the electronic, magnetic and optical properties of TMn@(ZnO)42 (TM = Fe,\nCo and Ni) hetero-nanostructure are investigated using the density functional\ntheory (DFT). It has been found that the core-shell nanostructure Fe13@(ZnO)42,\nCo15@(ZnO)42 and Ni15@(ZnO)42 are the most stable structures. Moreover, it is\nalso predicted that the variation of the magnetic moment and magnetism of Fe,\nCo and Ni in TMn@ZnO42 hetero-nanostructure mainly stems from effective\nhybridization between core TM-3d orbitals and shell O-2p orbitals, and a\nmagnetic moment inversion for Fe15@(ZnO)42 is investigated. Finally, optical\nproperties studied by calculations show a red shift phenomenon in the\nabsorption spectrum compared with the case of (ZnO)48."
    },
    {
        "anchor": "Reliable lattice dynamics from an efficient density functional: First principles predictions of lattice dynamics are of vital importance for\na broad range of topics in materials science and condensed matter physics. The\nlarge-scale nature of lattice dynamics calculations and the desire to design\nnovel materials with distinct properties demands that first principles\npredictions are accurate, transferable, efficient, and reliable for a wide\nvariety of materials. In this work, we demonstrate that the recently\nconstructed r2SCAN density functional meets this need for general systems by\ndemonstrating phonon dispersions for typical systems with distinct chemical\ncharacteristics. The functional's performance opens a door for phonon-mediated\nmaterials discovery from first principles calculations.",
        "positive": "Observed Metallization of Hydrogen Interpreted as a Band Structure\n  Effect: A recent experimental study of the metallization of hydrogen tracked the\ndirect band gap and vibron frequency via infrared measurements up to ~425 GPa\n[P. Loubeyre et al., Nature 577, 631 (2020)]. Above this pressure, the direct\ngap has a discontinuous drop to below the minimum experimentally accessible\nenergy (~0.1 eV). The authors suggested that this observation is caused by a\nstructural phase transition between the C2/c-24 molecular phase to another\nmolecular phase such as Cmca-12. Here, through ab initio calculations of\npressure dependent vibron frequency and direct band gap, we find that the\nexperimental data is consistent with the C2/c-24 phase up to 425 GPa, and\nsuggest that this consistency extends beyond that pressure. Specifically, we\nfind that qualitative changes in the band structure of the C2/c-24 phase lead\nto a discontinuous drop of the direct band gap, which can explain the observed\ndrop without a structural transition. This alternative scenario naturally\nexplains the absence of hysteresis in the measurements."
    },
    {
        "anchor": "Magnetism in 2D BN$_{1-x}$O$_x$ and B$_{1-x}$Si$_x$N: polarized\n  itinerant and local electrons: We use density functional theory based first-principles methods to study the\nmagnetism in a 2D hexagonal BN sheet induced by the different concentrations of\noxygen and silicon atoms substituting for nitrogen (O$_\\mathrm{N}$) and boron\n(Si$_\\mathrm{B}$) respectively. We demonstrate the possible formation of three\ndistinct phases based on the magnetization energy calculated self-consistently\nfor the ferromagnetic (ME$_{\\mathrm{FM}}$) and antiferromagnetic\n(ME$_{\\mathrm{AFM}}$) states, i.e. the paramagnetic phase with\nME$_{\\mathrm{FM}}$=ME$_{\\mathrm{AFM}}$, the ferromagnetic phase with\nME$_{\\mathrm{FM}}$$>$ME$_{\\mathrm{AFM}}$ and finally the polarized itinerant\nelectrons with finite ME$_{\\mathrm{FM}}$ but zero ME$_{\\mathrm{AFM}}$. While\nthe O$_\\mathrm{N}$ system was found to exist in all three phases, no tendency\ntowards the formation of the polarized itinerant electrons was observed for the\nSi$_\\mathrm{B}$ system though the existence of the other two phases was\nascertained. The different behavior of these two systems is associated with the\ndiverse features in the magnetization energy as a function of the oxygen and\nsilicon concentrations. Finally, the robustness of the polarized itinerant\nelectron phase is also discussed with respect to the O substitute atom\ndistributions and the applied strains to the system.",
        "positive": "Anomalous Spontaneous Reversal in Magnetic Heterostructures: We observe a thermally induced spontaneous magnetization reversal of\nepitaxial ferromagnet/antiferromagnet heterostructures under a constant applied\nmagnetic field. Unlike any other magnetic system, the magnetization\nspontaneously reverses, aligning anti-parallel to an applied field with\ndecreasing temperature. We show that this unusual phenomenon is caused by the\ninterfacial antiferromagnetic coupling overcoming the Zeeman energy of the\nferromagnet. A significant temperature hysteresis exists, whose height and\nwidth can be tuned by the field applied during thermal cycling. The hysteresis\noriginates from the intrinsic magnetic anisotropy in the system. The\nobservation of this phenomenon leads to open questions in the general\nunderstanding of magnetic heterostructures. Moreover, this shows that in\ngeneral heterogeneous nanostructured materials may exhibit unexpected phenomena\nabsent in the bulk."
    },
    {
        "anchor": "Flexoelectric fracture-filter effect in ferroelectrics: The propagation front of a crack generates large strain gradients and it is\ntherefore a strong source of gradient-induced polarization (flexoelectricity).\nHerein, we demonstrate that, in piezoelectric materials, a consequence of\nflexoelectricity is that crack propagation will be helped or hindered depending\non whether it is parallel or antiparallel to the piezoelectric polar axis. This\nmeans that the theory of fracture physics can no longer assume mechanical\nsymmetry in polar materials. The discovery of fracture asymmetry also has\npractical repercussions for the electromechanical fatigue of ferroelectrics and\npiezoelectric transducers, as well enabling a new degree of freedom for\ncrack-based nanopatterning.",
        "positive": "A More Flexible Realization of The SUNRED Algorithm: The high dissipation of integrated circuits means serious problems for\npackaging and for the design of complex electronic systems. Another important\narea of research and development nowadays is the integration of sensors and\nmicromechanical systems (MEMS) with electronic circuits. The original\nSuccessive Node Reduction (SUNRED) algorithm handles well the first area but\nrequire revision for electro-thermal or mechanical fields. As a first stage the\nupdated algorithm is able to solve thermal fields as the original, but with the\napplication of flexible boundary connection handling, it can be much faster\nthan the original. By using object-oriented program model the algorithm can\nhandle non-rectangular 3D fields, and SUNRED mesh resolution is arbitrary, not\nhave to be the power of two anymore."
    },
    {
        "anchor": "Site independent strong phonon-vacancy scattering in high temperature\n  ceramics ZrB$_2$ and HfB$_2$: Similar effects of metal and boron vacancies on phonon scattering and lattice\nthermal conductivity ($\\kappa_l$) of ZrB$_2$ and HfB$_2$ are reported. These\ndefects challenge the conventional understanding that associates larger impacts\nto bigger defects. We find the underlying reason to be a strong local\nperturbation caused by the boron vacancy that substantially changes the\ninteratomic force constants. In contrast, a long ranged but weaker perturbation\nis seen in the case metal vacancies. We show that these behaviours originate\nfrom a mixed metallic and covalent bonding nature in the metal diborides. The\nthermal transport calculations are performed in a complete \\textit{ab initio}\nframework based on Boltzmann transport equation and density functional theory.\nPhonon-vacancy scattering is calculated using \\textit{ab initio} Green's\nfunction approach. Effects of natural isotopes and grain boundaries on\n$\\kappa_l$ are also systematically investigated, however we find an influential\nrole of vacancies to explain large variations seen in the experiments. We\nfurther report a two-order of magnitude difference between the amorphous and\npure-crystal limits. Our results outline significant material design aspects\nfor these multi-functional high temperature ceramics.",
        "positive": "A route towards controlling the morphology of vertical graphene\n  nanosheets: Herein, an effort has given to sheds light on the effects of plasma process\nparameters on the growth of vertical graphene nanosheets (VGNs) by plasma\nenhanced chemical vapor deposition (PECVD. The parameters include substrate\ntemperature, microwave power and distance between plasma sources to substrate.\nThe significant influence of these variable parameters is observed on the\nmorphology, growth rate and crystallinity. Thus these parameters are found to\nbe deciding factors, which determine the surface reaction and growth kinetics\nthat governed the final structure and controlled morphology of VGNs. The\nactivation energy of the VGNs grown by PECVD is found to be 0.57 eV. A direct\nevidence of vertical growth through the nanographitic island is observed from\ntemperature dependent growth of VGNs. Such understanding on growth of VGNs is\nnot only useful for growth mechanism under plasma chemistry but also beneficial\nto get controlled and desired structure for field emission and energy storage\napplication."
    },
    {
        "anchor": "Non-magnetic impurities to induce magnetism in $\u03b1$-PbO crystal\n  structure: A new route to $d^0$ magnetism is established with help of the first\nprinciples methods. Non-magnetic interstitial impurities from group 14 in the\nperiodic table are found to induce $p$-orbital magnetism in polycrystalline\nPbO-type structures. The half-filled $p$-orbitals occupied by two electrons is\ngenerated on the impurity site for which the ferromagnetic state of high\nstability is guaranteed by the first Hund's rule. Since the impurity is\nembedded between layers of the host, its atomic radius is a key to tune not\nonly its solubility but also the magnetic behavior: the on-site stability of\nthe spin polarized state grows with reduction of the atomic radius while losing\nin the long-rang order interactions. However, for impurities of smaller radius\nthe weaker inter-site magnetic coupling can be compensated by their\nconcentration as the impurity solubility limit is shifted to higher magnitudes.",
        "positive": "Ni/Ni3C Core-Shell Nanochains and Its Magnetic Properties: One-Step\n  Synthesis at low temperature: One-dimensional Ni/Ni3C core-shell nanoball chains with an average diameter\nby around 30 nm were synthesized by means of a mild chemical solution method\nusing a soft template of trioctylphosphineoxide (TOPO). It was revealed that\nthe uniform Ni nanochains were capped with Ni3C thin shells by about 1 to 4 nm\nin thickness and each Ni core consists of polygrains. The coercivity of the\ncore-shell nanochains is much enhanced (600 Oe at 5 K) and comparable with\nsingle Ni nanowires due to the one-dimensional shape anisotropy. Deriving from\nthe distinctive structure of Ni core and Ni3C shell, this architecture may\npossess a possible bi-functionality. This unique architecture is also useful\nfor the study on the magnetization reversal mechanism of one-dimensional\nmagnetic nanostructure."
    },
    {
        "anchor": "Revisiting Phase Diagrams of Two-Mode Phase-Field Crystal Models: In this work, phase diagrams of a modified two-mode phase-field crystal (PFC)\nthat show two-dimensional (2D) and three-dimensional (3D) crystallographic\nstructures were determined by utilizing a free energy minimization method. In\nthis study the modified two-mode PFC model (presented by E. Asadi and M. Asle\nZaeem, Comput. Mater. Sci. 2015) was used, in which the free energy can be\nexactly minimized in each stable crystal structure allowing calculation of\naccurate phase diagrams for two-mode PFC models. Different crystal structures,\nsuch as square, triangle, body-centered cubic (bcc), face-centered cubic (fcc),\nand stripe lattice structures as well as their coexistence regions were\nconsidered in the calculations. The model parameters were discussed to\ncalculate phase diagrams that can be used as a guideline by other researchers\nfor studying solidification and solid state phase transformation using two-mode\nPFC model.",
        "positive": "Neutron scattering study of Kondo lattice antiferromagnet YbNiSi3: The Kondo lattice antiferromagnet YbNiSi3 was investigated by neutron\nscattering. The magnetic structure of YbNiSi3 was determined by neutron\ndiffraction on a single-crystalline sample. Inelastic scattering experiments\nwere also performed on a pulverized sample to study the crystalline electric\nfield (CEF) excitations. Two broad CEF excitations were observed, from which\nthe CEF parameters were determined. The temperature dependence of the magnetic\nsusceptibility chi and the magnetic specific heat Cmag were calculated using\nthe determined CEF model, and compared with previous results."
    },
    {
        "anchor": "Thiophene-Furan oligomers: Beyond-DFT Study of Electronic and Optical\n  Properties: Thiophene oligomers are an important class of organic materials for\nphotovoltaic applications, owing to their unique optoelectronic properties.\nRecently it was suggested that incorporation of furan units to the thiophene\nchains, maintaining the chain structure, namely thienylfuran linear oligomers,\ncan bring improvements to the final material. In this work, we present a\ntheoretical study of thiophene, furan and thienylfuran short chains, up to 4\nunits. Structural and electronic properties were obtained using Hartree-Fock\n(HF) and Density Functional Theory (DFT) calculations plus beyond mean-field\nmethodologies, specifically Second-order M\\\"oller-Plesset perturbation theory\non HF (HF-MP2) and many-body perturbation theory by the G0W0 approximation on\nDFT (G0W0@DFT). The optical properties were calculated on top of G0W0@DFT data\nusing the Bethe-Salpeter Equation. We investigate properties from the monomers\nT and F to tetramers with different sequencing of units TT, TF or FF, always\nbonded through the usual carbon atoms. As well known for the uniform\noligothiophene chains, also here for any TT sequencing we find a torsion angle\nof $150^{\\circ}$, while all other sequencing of units result planar, which can\nbe relevant for film producing. Also we find that the first optical transitions\nfor the oligomers reach a promising threshold of $\\sim 3$ eV at the tetramer\nlength, combined with ionization potentials around $\\sim 7$ eV, which confirms\nthe relevance of these organic compounds for photovoltaic applications.",
        "positive": "Electron-phonon coupling and electronic thermoelectric properties of\n  n-type PbTe driven near the soft-mode phase transition via lattice expansion: IV-VI materials are some of the most efficient bulk thermoelectric materials\ndue to their proximity to soft-mode phase transitions, which leads to low\nlattice thermal conductivity. It has been shown that the lattice thermal\nconductivity of PbTe can be considerably reduced by bringing PbTe closer to the\nphase transition e.g. via lattice expansion. However, the effect of soft phonon\nmodes on the electronic thermoelectric properties of such system remains\nunknown. Using first principles calculations, we show that the soft zone center\ntransverse optical phonons do not deteriorate the electronic thermoelectric\nproperties of PbTe driven closer to the phase transition via lattice expansion\ndue to external stress, and thus enhance the thermoelectric figure of merit. We\nfind that the optical deformation potentials change very weakly as the\nproximity to the phase transition increases, but the population and scattering\nphase space of soft phonon modes increase. Nevertheless, scattering between\nelectronic states near the band edge and soft optical phonons remains\nrelatively weak even very near the phase transition."
    },
    {
        "anchor": "Flexible Quasi-Three-Dimensional Terahertz Metamaterials: We characterize planar electric terahertz metamaterials fabricated on thin,\nflexible substrates using terahertz time-domain spectroscopy.\nQuasi-three-dimensional metamaterials are formed by stacking multiple\nmetamaterial layers. Transmission measurements reveal resonant band-stop\nbehavior that becomes stronger with an increasing number of layers. Extracted\nmetamaterial dielectric functions are shown to be independent of the number of\nlayers, validating the effective medium approximation. Limitations of this\napproximation are discussed.",
        "positive": "Anisotropy and Morphology of Strained III-V Heteroepitaxial Films: Strained coherent heteroepitaxy of III-V semiconductor films such as\nIn$_x$Ga$_{1-x}$As/GaAs has potential for electronic and optoelectronic\napplications such as high density logic, quantum computing architectures, laser\ndiodes, and other optoelectronic devices. Crystal symmetry can have a large\neffect on the morphology of these films and their spatial order. Often the\nformation of group IV strained heterostructures such as Ge deposited on Si is\nanalyzed using analytic models based on the Asaro-Tiller-Grinfeld instability.\nHowever, the governing dynamics of III-V 3D heterostructure formation has\ndifferent symmetry and is more anisotropic. The additional anisotropy appears\nin both the surface energy and the diffusivity. Here, the resulting anisotropic\ngoverning dynamics are studied to linear order. The resulting possible film\nmorphologies are compared with experimentally observed In$_x$Ga$_{1-x}$As/GaAs\nfilms. Notably it is found that surface-energy anisotropy plays a role at least\nas important as surface diffusion anisotropy if not more so, in contrast to\nprevious suppositions."
    },
    {
        "anchor": "\u03a0 Band Dispersion along Conjugated Organic Nanowires Synthesized on\n  a Metal Oxide Semiconductor: Surface confined dehalogenation reactions are versatile bottom-up approaches\nfor the synthesis of carbon-based nanostructures with predefined chemical\nproperties. However, for devices generally requiring low conductivity\nsubstrates, potential applications are so far severely hampered by the\nnecessity of a metallic surface to catalyze the reactions. In this work we\nreport the synthesis of ordered arrays of poly(p-phenylene) chains on the\nsurface of semiconducting TiO2(110) via a dehalogenative homocoupling of\n4,4\"-dibromoterphenyl precursors. The supramolecular phase is clearly\ndistinguished from the polymeric one using low energy electron diffraction and\nscanning tunneling microscopy as the substrate temperature used for deposition\nis varied. X ray photoelectron spectroscopy of C 1s and Br 3d core levels\ntraces the temperature of the onset of dehalogenation to around 475 K.\nMoreover, angle-resolved photoemission spectroscopy and tight-binding\ncalculations identify a highly dispersive band characteristic of a substantial\noverlap between the precursor's {\\pi} states along the polymer, considered as\nthe fingerprint of a successful polymerization. Thus, these results establish\nthe first spectroscopic evidence that atomically precise carbon based\nnanostructures can readily be synthesized on top of a transition-metal oxide\nsurface, opening the prospect for the bottom-up production of novel\nmolecule-semiconductor devices.",
        "positive": "Barkhausen-type noise in the resistance of antiferromagnetic Cr thin\n  films: We present an experimental study of the changes generated on the electrical\nresistance $R(T)$ of epitaxial Cr thin films by the transformation of quantized\nspin density wave domains as the temperature is changed. A characteristic\nresistance noise appears only within the same temperature region where a\ncooling-warming cycle in $R(T)$ displays hysteretic behavior. We propose an\nanalysis based on an analogy with the Barkhausen noise seen in ferromagnets.\nThere fluctuations in the magnetization $M(H)$ occur when the magnetic field\n$H$ is swept. By mapping $M \\rightarrow \\Psi_0$ and $H \\rightarrow T$, where\n$\\Psi_0$ corresponds to the order parameter of the spin density wave, we\ngeneralize the Preisach model in terms of a random distribution of {\\it\nresistive hysterons} to explain our results. These hysterons are related to\ndistributions of quantized spin density wave domains with different sizes,\nlocal energies and number of nodes."
    },
    {
        "anchor": "Some physical properties of lead iron niobate: The results of the X-ray, microscopic, magnetic, and dielectric measurements\nperformed for PFN single crystals and ceramic samples are presented. The\ninfluence of the technological conditions on selected physical properties of\nthe materials examined is shown.",
        "positive": "Machine Learning the Metastable Phase Diagram of Materials: Phase diagrams are an invaluable tool for material synthesis and provide\ninformation on the phases of the material at any given thermodynamic condition.\nConventional phase diagram generation involves experimentation to provide an\ninitial estimate of thermodynamically accessible phases, followed by use of\nphenomenological models to interpolate between the available experimental data\npoints and extrapolate to inaccessible regions. Such an approach, combined with\nfirst-principles calculations and data-mining techniques, has led to exhaustive\nthermodynamic databases albeit at distinct thermodynamic equilibria. In\ncontrast, materials during their synthesis, operation, or processing, may not\nreach their thermodynamic equilibrium state but, instead, remain trapped in a\nlocal free energy minimum, that may exhibit desirable properties. Mapping these\nmetastable phases and their thermodynamic behavior is highly desirable but\ncurrently lacking. Here, we introduce an automated workflow that integrates\nfirst principles physics and atomistic simulations with machine learning (ML),\nand high-performance computing to allow rapid exploration of the metastable\nphases of a given elemental composition. Using a representative material,\ncarbon, with a vast number of metastable phases without parent in equilibrium,\nwe demonstrate automatic mapping of hundreds of metastable states ranging from\nnear equilibrium to those far-from-equilibrium. Moreover, we incorporate the\nfree energy calculations into a neural-network-based learning of the equations\nof state that allows for construction of metastable phase diagrams. High\ntemperature high pressure experiments using a diamond anvil cell on graphite\nsample coupled with high-resolution transmission electron microscopy are used\nto validate our metastable phase predictions. Our introduced approach is\ngeneral and broadly applicable to single and multi-component systems."
    },
    {
        "anchor": "Electrostatics in Periodic Slab Geometries II: In a previous paper a method was developed to subtract the interactions due\nto periodically replicated charges (or other long-range entities) in one\nspatial dimension. The method constitutes a generalized \"electrostatic layer\ncorrection\" (ELC) which adapts any standard 3D summation method to slab-like\nconditions. Here the implementation of the layer correction is considered in\ndetail for the standard Ewald (EW3DLC) and the PPPM mesh Ewald (PPPMLC)\nmethods. In particular this method offers a strong control on the accuracy and\nan improved computational complexity of O(N log N) for mesh-based\nimplementations. We derive anisotropic Ewald error formulas and give some\nfundamental guidelines for optimization. A demonstration of the accuracy, error\nformulas and computation times for typical systems is also presented.",
        "positive": "Swift Heavy Ion Induced Modification Studies of C60 Thin Films: Modification induced by 110 MeV Ni ion irradiated thin film samples of C60 on\nSi and quartz substrates were studied at various fluences. The pristine and\nirradiated samples were investigated using Raman spectroscopy, electrical\nconductivity and optical absorption spectroscopy. The Raman data and band gap\nmeasurements indicate that swift ions at low fluences result in formations that\ninvolve multiple molecular units like dimer or polymer. High fluence\nirradiation resulted in sub-molecular formations and amorphous semiconducting\ncarbon, indicating overall damage of the fullerene molecules. These\nsub-molecular units have been identified with nanocrystalline diamond and\nnanocrystalline graphite like formations."
    },
    {
        "anchor": "The effect of local dipole moments on the structure and lattice dynamics\n  of K0.98Li0.02TaO3: We present high energy x-ray (67 keV) and neutron scattering measurements on\na single crystal of K$_{1-x}$Li$_x$TaO$_3$ for which the Li content ($x=0.02$)\nis less than $x_c = 0.022$, the critical value below which no structural phase\ntransitions have been reported in zero field. While the crystal lattice does\nremain cubic down to T=10 K under both zero-field and field-cooled ($E \\le 4$\nkV/cm) conditions, indications of crystal symmetry lowering are seen at\n$T_C=63$ K where the Bragg peak intensity changes significantly. A strong and\nfrequency-dependent dielectric permittivity is observed at ambient pressure, a\ndefining characteristic of relaxors. However an extensive search for static\npolar nanoregions, which is also widely associated with relaxor materials,\ndetected no evidence of elastic neutron diffuse scattering between 300 K and 10\nK. Neutron inelastic scattering methods were used to characterize the\ntransverse acoustic and optic phonons (TA1 and TO1 modes) near the (200) and\n(002) Bragg peaks. The zone center TO1 mode softens monotonically with cooling\nbut never reaches zero energy in either zero field or in external electric\nfields of up to 4 kV/cm. These results are consistent with the behavior\nexpected for a dipolar glass in which the local polar moments are frozen and\nexhibit no long-range order at low temperatures.",
        "positive": "A statistical analysis of pores and micro-cracks in nuclear graphite: Microstructure characterization is of great value to understanding nuclear\ngraphite's properties and irradiation behavior. However, graphite is soft and\ncould be easily damaged during sample preparation. A three-step polishing\nmethod involving mechanical polishing, ion milling and rapid oxidation is\nproposed for graphite. Ion milling is adopted to remove the broken graphite\npieces produced by mechanical polishing. Rapid oxidation is then adopted to\nremove irradiation-induced damage layer during ion milling. The Raman spectra\nshow very low G peak width and ID/IG ratio after rapid oxidation, indicating a\nsurface completely free from artificial defects. The micro-cracks which were\nconventionally observed via a transmission electron microscope can be observed\non rapid-oxidized surface in a scanning electron microscope. By digital image\nprocessing, the micro-cracks along with the gas-escape pores in nuclear\ngraphite IG-110 are statistically analyzed. Porosity's distributions on crack\n(pore) size (spanning from 10 nm to 100 um) are given, which could help to\nunderstand and simulate graphite's performances in reactors."
    },
    {
        "anchor": "First principles study on small ZrAln and HfAln clusters: structural,\n  stability, electronic states and CO2 adsorption: We report a first principles study based on density functional theory on the\nstructural and electronic properties of transition metal Zr and Hf doped small\naluminum clusters with 1 to 7 aluminum atoms. We have used B3PW91 with LANL2DZ\nbasis set in Gaussian 09 package. The stability analysis reveals that the ZrAl4\nand HfAl4 structures with C2v symmetry and square pyramid geometry are lowest\nenergy structures. The most stable structures in ZrAl5 and HfAl5 are distorted\ntetrahedron type structure with symmetry C1. The binding energies per atom for\ntransition metal doped Aln clusters increases with the cluster size, while the\nsecond order difference in total energy show oscillatory behavior with even and\nodd cluster size. The HOMO and LUMO gap for ZrAln is larger than the HfAln\nclusters except for n being 1 and 3. The HfAl6 has more tendency to accept or\ngive away electrons. The negative charge exists on Zr and Hf indicating that\nthe electron transfers from Al atom to transition metal, Zr and Hf. The\nthermodynamical analysis suggest that the HfAl6 cluster has highest\nexothermicity compared to not only all considered Al clusters but also other\ntransition metal doped Al clusters reported in J. Phys. Chem. C, 120, 10027,\n2016.",
        "positive": "Interface-dominated Growth of a Metastable Novel Alloy Phase: A new \\textit{D0$_{23}$} metastable phase of Cu$_3$Au is found to grow at the\ninterfaces of Au/Cu multilayers deposited by magnetron sputtering. The extent\nof formation of this novel alloy phase depends upon an optimal range of\ninterfacial width primarily governed by the deposition wattage of the\ndc-magnetron used. Such interfacially confined growth is utilized to grow a\n$\\sim$ 300 nm thick Au/Cu multilayer with thickness of each layer nearly equal\nto the optimal interfacial width which was obtained from secondary ion mass\nspectrometry (SIMS) data. This growth technique is observed to enhance the\nformation of the novel alloy phase to a considerable extent. SIMS depth profile\nalso indicates that the mass fragment corresponding to Cu$_3$Au occupies the\nwhole film while x-ray diffraction (XRD) shows almost all the strong peaks\nbelonging to the \\textit{D0$_{23}$} structure. High resolution cross-sectional\ntransmission electron microscopy (HR-XTEM) shows the near perfect growth of the\nindividual layers and also the lattice image of the alloy phase in the\ninterfacial region. Vacuum annealing of the alloy film and XRD studies indicate\nstabilization of the \\textit{D0$_{23}$} phase at $\\sim$ 150$^{\\circ}$C. The\nrole of interfacial confinement, the interplay between interfacial strain and\nfree energy and the hyperthermal species generated during the sputtering\nprocess are discussed."
    },
    {
        "anchor": "Scattering by Atomic Spins and Magnetoresistance in Dilute Magnetic\n  Semiconductors: We studied electrical transport in magnetic semiconductors, which is\ndetermined by scattering of free carriers off localized magnetic moments. We\ncalculated the scattering time and the mobility of the majority and\nminority-spin carriers with both the effects of thermal spin fluctuations and\nof spatial disorder of magnetic atoms taken into account. These are responsible\nfor the magnetic-field dependence of electrical resistivity. Namely, the\napplication of the external magnetic field suppresses the thermodynamic spin\nfluctuations thus promoting negative magnetoresistance. Simultaneously,\nscattering off the built-in spatial fluctuations of the atomic spin\nconcentrations may increase with the magnetic field. The latter effect is due\nto the growth of the magnitude of random local Zeeman splittings with the\nmagnetic field. It promotes positive magnetoresistance. We discuss the role of\nthe above effects on magnetoresistance of non-degenerate semiconductors where\nmagnetic impurities are electrically active or neutral.",
        "positive": "Large Rashba unidirectional magnetoresistance in the Fe/Ge(111)\n  interface states: The structure inversion asymmetry at surfaces and interfaces give rise to the\nRashba spin-orbit interaction (SOI), that breaks the spin degeneracy of surface\nor interface states. Hence, when an electric current runs through a surface or\ninterface, this Rashba effect generates an effective magnetic field acting on\nthe electron spin. This provides an additional tool to manipulate the spin\nstate in materials such as Si and Ge that, in their bulk form, possess\ninversion symmetry (or lack structural inersion asymmetry). The existence of\nRashba states could be demonstrated by photoemission spectroscopy at the\ninterface between different metals and Ge(111) and by spin-charge conversion\nexperiments at the Fe/Ge(111) interface even though made of two light elements.\nIn this work, we identify the fingerprint of the Rashba states at the\nFe/Ge(111) interface by magnetotransport measurements in the form of a large\nunidirectional magnetoresistance of up to 0.1 \\%. From its temperature\ndependence, we find that the Rashba energy splitting is larger than in pure\nGe(111) subsurface states."
    },
    {
        "anchor": "Hard x-ray emission spectroscopy: a powerful tool for the\n  characterization of magnetic semiconductors: This review aims to introduce the x-ray emission spectroscopy (XES) and\nresonant inelastic x-ray scattering (RIXS) techniques to the materials\nscientist working with magnetic semiconductors (e.g. semiconductors doped with\n3d transition metals) for applications in the field of spin-electronics. We\nfocus our attention on the hard part of the x-ray spectrum (above 3 keV) in\norder to demonstrate a powerful element- and orbital-selective characterization\ntool in the study of bulk electronic structure. XES and RIXS are\nphoton-in/photon-out second order optical processes described by the\nKramers-Heisenberg formula. Nowadays, the availability of third generation\nsynchrotron radiation sources permits applying such techniques also to dilute\nmaterials, opening the way for a detailed atomic characterization of\nimpurity-driven materials. We present the K{\\beta} XES as a tool to study the\noccupied valence states (directly, via valence-to-core transitions) and to\nprobe the local spin angular momentum (indirectly, via intra-atomic exchange\ninteraction). The spin sensitivity is employed, in turn, to study the\nspin-polarized unoccupied states. Finally, the combination of RIXS with\nmagnetic circular dichroism (RIXS-MCD) extends the possibilities of standard\nmagnetic characterization tools.",
        "positive": "Origin of the anomalous mass renormalization in metallic quantum well\n  states of correlated oxide SrVO$_3$: $In$ $situ$ angle-resolved photoemission spectroscopy (ARPES) has been\nperformed on SrVO$_3$ ultrathin films, which show metallic quantum well (QW)\nstates, to unveil the origin of the anomalous mass enhancement in the QW\nsubbands. The line-shape analysis of the ARPES spectra reveals that the\nstrength of the electron correlation increases as the subband bottom energy\napproaches the Fermi level. These results indicate that the anomalous\nsubband-dependent mass enhancement mainly arises from the quasi-one-dimensional\ncharacter of confined V $3d$ states as a result of their orbital-selective\nquantization."
    },
    {
        "anchor": "Direct correlation between strengthening mechanisms and electrical noise\n  in strained copper wires: We have measured the resistance noise of copper metallic wires during a\ntensile stress. The time variation of the main resistance is continuous up to\nthe wire breakdown, but its fluctuations reveal the intermittent and\nheterogeneous character of plastic flow. We show in particular direct\ncorrelations between strengthening mechanisms and noise spectra\ncharacteristics.",
        "positive": "Photoconductivity of CdS-CdSe granular films: influence of\n  microstructure: We study experimentally the photoconductivity of CdS-CdSe sintered granular\nfilms obtained by the screen printing method. We mostly focus on the\ndependences of photoconductivity on film's microstructure, which varies with\nchanging heat-treatment conditions. The maximum photoconductivity is found for\nsamples with compact packing of individual grains, which nevertheless are\nseparated by gaps. Such a microstructure is typical for films heat-treated\nduring an intermediate (optimal) time. In order to understand whether the\ndominant mechanism of charge transfer is identical with the one in\nmonocrystals, we perform temperature measurements of photoresistance.\nCorresponding curves have the same peculiar nonmonotonic shape as in CdSe\nmonocrystals, from which we conclude that the basic mechanism is also the same.\nIt is suggested that the optimal heat-treatment time appears as a result of a\ncompetition between two mechanisms: improvement of film's connectivity and its\noxidation. Photoresistance is also measured in vacuum and in helium atmosphere,\nwhich suppress oxygen and water absorption/chemisorption at intergrain\nboundaries. We demonstrate that this suppression increases photoconductivity,\nespecially at high temperatures."
    },
    {
        "anchor": "Inelastic Charge Transfer Dynamics in Donor-Bridge-Acceptor Systems\n  Using Optimal Modes: We present a novel {\\em ab initio} approach for computing intramolecular\ncharge and energy transfer rates based upon a projection operator scheme that\nparses out specific internal nuclear motions that accompany the electronic\ntransition. Our approach concentrates the coupling between the electronic and\nnuclear degrees of freedom into a small number of reduced harmonic modes that\ncan be written as linear combinations of the vibrational normal modes of the\nmolecular system about a given electronic minima. Using a time-convolutionless\nmaster-equation approach, parameterized by accurate quantum-chemical methods,\nwe benchmark the approach against experimental results and predictions from\nMarcus theory for triplet energy transfer for a series of donor-bridge-acceptor\nsystems. We find that using only a single reduced mode--termed the \"primary\"\nmode, one obtains an accurate evaluation of the golden-rule rate constant and\ninsight into the nuclear motions responsible for coupling the initial and final\nelectronic states. We demonstrate the utility of the approach by computing the\ninelastic electronic transition rates in a model donor-bridge-acceptor complex\nthat has been experimentally shown that its exciton transfer pathway can be\nradically modified by mode-specific infrared excitation of its vibrational\nmode.",
        "positive": "Carrier-mediated magnetoelectricity in complex oxide heterostructures: While tremendous success has been achieved to date in creating both single\nphase and composite magnetoelectric materials, the quintessential\nelectric-field control of magnetism remains elusive. In this work, we\ndemonstrate a linear magnetoelectric effect which arises from a novel\ncarrier-mediated mechanism, and is a universal feature of the interface between\na dielectric and a spin-polarized metal. Using first-principles density\nfunctional calculations, we illustrate this effect at the SrRuO$_3$/SrTiO$_3$\ninterface and describe its origin. To formally quantify the magnetic response\nof such an interface to an applied electric field, we introduce and define the\nconcept of spin capacitance. In addition to its magnetoelectric and spin\ncapacitive behavior, the interface displays a spatial coexistence of magnetism\nand dielectric polarization suggesting a route to a new type of interfacial\nmultiferroic."
    },
    {
        "anchor": "Spin-Diffusion Lengths in Metals and Alloys, and Spin-Flipping at\n  Metal/Metal Interfaces: an Experimentalist's Critical Review: In magnetoresistive (MR) studies of magnetic multilayers composed of\ncombinations of ferromagnetic (F) and non-magnetic (N) metals, the magnetic\nmoment (or related 'spin') of each conduction electron plays a crucial role,\nsupplementary to that of its charge. While initial analyses of MR in such\nmultilayers assumed that the direction of the spin of each electron stayed\nfixed as the electron transited the multilayer, we now know that this is true\nonly in a certain limit. Generally, the spins 'flip' in a distance\ncharacteristic of the metal, its purity, and the temperature. They can also\nflip at F/N or N1/N2 interfaces. In this review we describe how to measure the\nlengths over which electron moments flip in pure metals and alloys, and the\nprobability of spin-flipping at metallic interfaces. Spin-flipping within\nmetals is described by a spin-diffusion length,l^M(sf), where the metal M = F\nor N. Spin-diffusion lengths are the characteristic lengths in the\ncurrent-perpendicular-to-plane (CPP) and lateral non-local (LNL) geometries\nthat we focus upon in this review. In certain simple cases, l^N(sf) sets the\ndistance over which the CPP-MR and LNL-MR decrease as the N-layer thickness\n(CPP-MR) or N-film length (LNL) increases, and l^F(sf) does the same for\nincrease of the CPP-MR with increasing F-layer thickness. Spin-flipping at\nM1/M2 interfaces can be described by a parameter, delta(M1/M2), which\ndetermines the spin-flipping probability, P = 1 - exp(-delta). Increasing\ndelta(M1/M2) usually decreases the MR. We list measured values of these\nparameters and discuss the limitations on their determinations.",
        "positive": "Crystal structure of dense pseudo-cubic boron allotrope, pc-B52, by\n  powder X-ray diffraction: During past years, a number of reports have been published on synthesis of\ntetragonal allotrope of boron, t-B52 phase. However, no unambiguous\ncharacterization of the crystal structure has been performed to the present\ntime, while remarkable variation of the a/c lattice-parameter ratio raises\nstrong doubts about its uniqueness. Here the Rietveld refinement of the crystal\nstructure of the high pressure - high temperature boron phase synthesized by a\ndirect solid-state transformation of rhombohedral beta-B106 at 20 GPa and 2500\nK has been reported for the first time. Although this boron allotrope belongs\nto the t-B52 type, its structure can be considered as pseudo-cubic with the a/c\nratio of sqr(2)."
    },
    {
        "anchor": "Thermal contact resistance between two nanoparticles: We compute the thermal conductance between two nanoparticles in contact based\non the Molecular Dynamics technique. The contact is generated by letting both\nparticles stick together under van der Waals attractions. The thermal\nconductance is derived from the fluctuation-dissipation theorem and the time\nfluctuations of the exchanged power. We show that the conductance is\nproportional to the atoms involved in the thermal interaction. In the case of\nsilica, the atomic contribution to the thermal conductance is in the range of\n0.5 to 3 nW.K-1. This result fits to theoretical predictions based on\ncharacteristic times of the temperature fluctuation. The order of magnitude of\nthe contact conductance is 1 \\mu W.K-1 when the cross section ranges from 1 to\n10nm2.",
        "positive": "Band structure effects on the interaction of charged particles with\n  solids: A survey is presented of current investigations of the impact of band\nstructure effects on various aspects of the interaction of charged particles\nwith real solids. The role that interband transitions play in the decay\nmechanism of bulk plasmons is addressed, and results for plasmon linewidths in\nAl and Si are discussed. {\\it Ab initio} calculations of the electronic energy\nloss of ions moving in Al and Si are also presented, within linear response\ntheory, from a realistic description of the one-electron band structure and a\nfull treatment of the dynamic electronic response of valence electrons. Both\nrandom and position-dependent stopping powers of valence electrons are\ncomputed."
    },
    {
        "anchor": "Epitaxial growth of complex oxides on silicon by enhanced surface\n  diffusion in large area pulsed laser deposition: Homogeneous highly epitaxial LaSrMnO3 (LSMO) thin films have been grown on\nYttria-stabilized-Zirconia (YsZ) / CeO2 buffer layers on technological relevant\n4\" silicon wafers using a Twente Solid State Technology B.V. (TSST) developed\nlarge area Pulsed Laser Deposition (PLD) setup. We study and show the results\nof the effect of an additional SrRuO3 buffer layer on the growth temperature\ndependent structural and magnetic properties of LSMO films. With the\nintroduction of a thin SrRuO3 layer on top of the buffer stack, LSMO films show\nferromagnetic behaviour for growth temperatures as low as 250C. We suggest that\noccurrence of epitaxial crystal growth of LSMO at these low growth temperatures\ncan be understood by an improved surface diffusion, which ensures sufficient\nintermixing of surface species for formation of the correct phase. This\nintermixing is necessary because the full plume is collected on the 4\" wafer\nresulting in a compositional varying flux of species on the wafer, in contrast\nto small scale experiments.",
        "positive": "An Isotropic Discretization with Semi-implicit Approach for Phase Field\n  Model of Alloy Solidification: Quantitative phase field models have been extensively used to study the\nsolidification behavior of alloys under different conditions. However, a\nlongstanding challenge of phase field models is the directional bias caused by\nthe discretization-induced lattice effects. In particular, widely used\ndiscretization methods may introduce significant spurious anisotropy for\nsimulations of polycrystalline solidification. In this paper, we demonstrate a\nfeasible 2D discretization strategy utilizing a hexagonal mesh to reduce the\nlattice-induced anisotropy of the phase field model. The leading differential\nterms of the 2D discretization methods are analyzed by using known methods in\nFourier space. Using Taylor expansion of discrete Fourier Transform up to sixth\norder, we found that the proposed discretization strategy is more accurate and\nisotropic than other methods, including the isotropic discretization recently\nproposed by Ji et al.[1]. Additionally, the proposed 2D discretization method\ncan be easily incorporated into a semi-implicit algorithm to solve phase field\nequations, thereby greatly reducing time step constraints and improving\ncomputational efficiency compared to explicit approaches. To prove the accuracy\nand efficiency of the proposed isotropic discretization with semi-implicit\nalgorithm, 2D simulations of alloy solidification with different discretization\nschemes were performed and compared. We show that the proposed discretization\nusing a hexagonal mesh can drastically reduce grid-induced anisotropy compared\nto conventional methods."
    },
    {
        "anchor": "In-situ formation of SiGe alloy by electron beam evaporation and the\n  effect of post deposition annealing on the energy band gap: We report the synthesis of polycrystalline (poly)-SiGe alloy thin films\nthrough solid state reaction of Si/Ge multilayer thin films on Si and glass\nsubstrates at low temperature of 500 {\\deg}C. The pristine thin film was\ndeposited using electron beam evaporation with optimized in-situ substrate\nheating. Our results show the co-existence of amorphous Si (a-Si) phase along\nwith the poly-SiGe phase in the pristine thin film. The a-Si phase was found to\nsubsume into the SiGe phase upon post deposition annealing in the temperature\nrange from 600 to 800 {\\deg}C. Additionally, dual energy band gaps could be\nobserved in the optical properties of the annealed poly-SiGe thin films. The\nstoichiometric evolution of the pristine thin film and its subsequent effect on\nthe band gap upon annealing are discussed on the basis of diffusion\ncharacteristics of Si in poly-SiGe.",
        "positive": "Experimental Signatures of Spin Superfluid Ground State in Canted\n  Antiferromagnet Cr2O3 via Nonlocal Spin Transport: Spin superfluid is a novel emerging quantum matter arising from the\nBose-Einstein condensate (BEC) of spin-1 bosons. We demonstrate the spin\nsuperfluid ground state in canted antiferromagnetic Cr2O3 thin film at low\ntemperatures via nonlocal spin transport. A large enhancement of the nonlocal\nspin signal is observed below ~ 20 K, and it saturates from ~ 5 K down to 2 K.\nWe show that the spins can propagate over very long distances (~ 20 micro\nmeters) in such spin superfluid ground state and the nonlocal spin signal\ndecreases very slowly as the spacing increases with an inverse relationship,\nwhich is consistent with theoretical prediction. Furthermore, spin\nsuperfluidity has been investigated in the canted antiferromagnetic phase of\nthe (11-20)-oriented Cr2O3 film, where the magnetic field dependence of the\nassociated critical temperature follows a two-thirds power law near the\ncritical point. The experimental demonstration of the spin superfluid ground\nstate in canted antiferromagnet will be extremely important for the fundamental\nphysics on the BEC of spin-1 bosons and paves the way for future spin\nsupercurrent devices, such as spin-Josephson junctions."
    },
    {
        "anchor": "Solvation of the Morpholinium Cation in Acetonitrile. Effect of an Anion: Ionic liquids constitute a fast growing class of compounds finding multiple\napplications in science and technology. Morpholinium-based ionic liquids\n(MBILs) and their mixtures with polar molecular co-solvents are interesting as\nsustainable electrolyte systems for electrochemistry. We investigate local\nstructures of protic and propton-free morpholinium cations in acetonitrile\n(ACN) using semi-empirical molecular dynamics (MD) simulations. An impact of an\nanion (acetate) on the cation solvation regularities is discussed. Unlike\noxygen, nitrogen of the morpholine ring is a strong electrophilic binding\ncenter. This site is responsible for the interactions of the cation with the\nsolvent and with the anion. In protic MBILs, the role of nitrogen is delegated\nto the proton, which is linked to nitrogen. The acetate anion weakens solvation\nof the cation due to occupation of space near nitrogen or proton. The analysis\nreveals a favorable solvation of MBILs in ACN, which is a prerequisite for a\nnew high-performance electrolyte system. The reported structural data are\nvalidated through a point-to-point comparison with the MP2 post-Hartree-Fock\ntheory.",
        "positive": "Giant magnetoimpedance: new electrochemical option to monitor surface\n  effects?: Magnetoimpedance, MI, change due to surface modification of the sensitive\nelement caused by biofluids was studied with the aim of creating a robust\nsensor capable of separating the chemical surface modification from the sensing\nprocess. A MI sensor prototype with an as-quenched FeCoSiB amorphous ribbon\nsensitive element was designed and calibrated for a frequency range of 0.5 to\n10 MHz at an intensity of the current of 60 mA. Measurements as a function of\nthe exposure time were made, first, in a regime where chemical surface\nmodification and sensing were separated and then, in a regime where they were\nnot separated (in a bath for fluids). The MI variation was explained by the\nchange of the surface magnetic anisotropy. It was shown that the\nmagnetoimpedance effect can be successfully employed as a new electrochemical\noption to probe the electric features of surface-modified magnetic electrodes\nwhen the biofluid, the material of the sensitive element, and the detection\nconditions are properly selected and synergetically adjusted."
    },
    {
        "anchor": "Berry Flux Diagonalization: Application to Electric Polarization: The switching polarization of a ferroelectric is a characterization of the\ncurrent that flows due to changes in polarization when the system is switched\nbetween two states. Computation of this change in polarization in crystal\nsystems has been enabled by the modern theory of polarization, where it is\nexpressed in terms of a change in Berry phase as the material switches. It is\nstraightforward to compute this change of phase, but only modulo $2\\pi$,\nrequiring a branch choice from among a lattice of values separated by $2\\pi$.\nThe measured switching polarization depends on the actual path along which the\nmaterial switches, which in general involves nucleation and growth of domains\nand is therefore quite complex. In this work, we present a physically motivated\napproach for predicting the experimentally measured switching polarization that\ninvolves separating the change in phase between two states into as many\ngauge-invariant smaller phase changes as possible. As long as the magnitudes of\nthese smaller phase changes remain smaller than $\\pi$, their sum forms a phase\nchange which corresponds to the change one would find along any path involving\nminimal evolution of the atomic and electronic structure. We show that for\ntypical ferroelectrics, including those that would have otherwise required a\ndensely sampled path, this technique allows the switching polarization to be\ncomputed without any need for intermediate sampling between oppositely\npolarized states.",
        "positive": "Cycloaddition Functionalizations to Preserve or Control the Conductance\n  of Carbon Nanotubes: We identify a class of covalent functionalizations that preserves or controls\nthe conductance of single-walled metallic carbon nanotubes. [2+1]\ncycloadditions can induce bond cleaving between adjacent sidewall carbons,\nrecovering in the process the $sp^2$ hybridization and the ideal conductance of\nthe pristine tubes. This is radically at variance with the damage permanently\ninduced by other common ligands, where a single covalent bond is formed with a\nsidewall carbon. Chirality, curvature, and chemistry determine bond cleaving,\nand in turn the electrical transport properties of a functionalized tube. A\nwell-defined range of diameters can be found for which certain addends exhibit\na bistable state, where the opening or closing of the sidewall bond,\naccompanied by a switch in the conductance, could be directed with chemical,\noptical or thermal means."
    },
    {
        "anchor": "The Microstructure of Tool Steel after Low Temperature Ion Nitriding: The microstructural development in H13 tool steel upon nitriding by an ion\nbeam process was investigated. The nitriding experiments were performed at a\nrelatively low temperature of about 400\\deg C and at constant ion beam energy\n(400 eV) of different doses in a high-vacuum preparation chamber; the ion\nsource was fed with high purity nitrogen gas. The specimens were characterized\nby X-ray photoelectron spectroscopy (XPS), electron probe microanalysis (EPMA),\nscanning and transmission electron microscopy (SEM and TEM), and grazing\nincidence and Bragg-Brentano X-ray diffractometry. In particular, the influence\nof the nitrogen surface concentration on the development of the nitrogen\nconcentration-depth profile and the possible precipitation of alloying element\nnitrides are discussed.",
        "positive": "Magnetic and structural properties of Co$_2$MnSi based Heusler compound: The influence of antisite disorder occupancies on the magnetic properties of\nthe half-metallic Co$_2$MnSi compound was studied by experimental techniques\nand first-principles calculations. The neutron diffraction studies show almost\nidentical amount of Mn and Co disorders of 6.5\\% and 7.6\\%, which was found to\nbe in good agreement with density functional theory (DFT) calculations of the\nstable Co$_2$MnSi system with the corresponding disorders. DFT studies reveal\nthat antiferromagnetic interactions introduced by Mn disorder lead to a\nreduction of the net magnetic moment. The results are discussed in conjunction\nwith neutron diffraction and magnetization measurements. Transport property\nmeasurement under magnetic field up to 9 Tesla revealed a positive\nmagnetoresistance for bulk Co$_2$MnSi that persists up to room temperature. A\nCurie temperature of $\\sim$1014 K was determined for the compound by high\ntemperature electrical resistivity and dilatometry measurements."
    },
    {
        "anchor": "Spin injection efficiency from two adjoining ferromagnetic metals into a\n  two-dimensional electron gas: In order to enhance spin injection efficiency from ferromagnetic (FM) metal\ninto a two-dimensional electron gas (2DEG), we introduce another FM metal and\ntwo tunnel barriers (I) between them to investigate the current polarization in\nsuch ballistic FM/I/FM/I/2DEG junction. Our treatment is based on the\nfree-electron scattering theory. It is found that due to quantum interference\neffect, the magnitude and sign of the current polarization exhibits periodical\noscillating behavior with variation of the thickness of the middle FM metal\nlayer or its exchange energy strength. For some suitable parameters, the spin\ninjection efficiency may arrive over 80% in this junction and can also be\ncontrolled by the electron density of 2DEG. Our results may shed light on the\ndevelopment of new spin-polarized device.",
        "positive": "Relaxation in Ordered Assembly of Magnetic Nanoparticles: We study the relaxation characteristics in the two-dimensional ($l^{}_x\n\\times l^{}_y$) array of magnetic nanoparticles (MNPs) as a function of aspect\nratio $A^{}_r=l^{}_y/l^{}_x$, dipolar interaction strength $h^{}_d$ and\nanisotropy axis orientation using computer simulation. The anisotropy axes of\nall the MNPs are assumed to have the same direction, $\\alpha$ being the\norientational angle. Irrespective of $\\alpha$ and $A^{}_r$, the functional form\nof the magnetization-decay curve is perfectly exponentially decaying with\n$h^{}_d\\leq0.2$. There exists a transition in relaxation behaviour at\n$h^{}_d\\approx0.4$; magnetization relaxes slowly for $\\alpha\\leq45^\\circ$; it\nrelaxes rapildy with $\\alpha>45^\\circ$. Interestingly, it decays rapidly for\n$h^{}_d>0.6$, irrespective of $\\alpha$. It is because the dipolar interaction\npromotes antiferromagnetic coupling in such cases. There is a strong effect of\n$\\alpha$ on the magnetic relaxation in the highly anisotropic system\n($A^{}_r\\geq25$). Interesting physics unfolds in the case of a huge aspect\nratio $A^{}_r=400$. There is a rapid decay of magnetization with $\\alpha$, even\nfor weakly interacting MNPs. Remarkably, magnetization does not relax even with\na moderate value of $h^{}_d=0.4$ and $\\alpha=0^\\circ$ because of ferromagnetic\ncoupling dominance. Surprisingly, there is a complete magnetization reversal\nfrom saturation (+1) to $-1$ state with $\\alpha>60^\\circ$. The dipolar field\nand anisotropy axis tend to get aligned antiparallel to each other in such a\ncase. The effective N\\'eel relaxation time $\\tau^{}_N$ depends weakly on\n$\\alpha$ for small $h^{}_d$ and $A^{}_r\\leq25.0$. For large $A^{}_r$, there is\na rapid fall in $\\tau^{}_N$ as $\\alpha$ is incremented from 0 to $90^\\circ$.\nThese results benefit applications in data and energy storages where such\ncontrolled magnetization alignment and desired structural anisotropy are\ndesirable."
    },
    {
        "anchor": "Growth of single wall carbon nanotubes from $^{13}$C isotope labelled\n  organic solvents inside single wall carbon nanotube hosts: Exploring the synthesis of novel molecular nanostructures has been in the\nforefront of material research in the last decade. One of the most interesting\nnanostructures are single wall carbon nanotubes (SWCNTs). Their catalyst free\ngrowth, however, remains an elusive goal. Here, we present the growth of single\nwall carbon nanotubes from organic solvents such as benzene and toluene in a\nconfined environment, inside a host SWCNT. The solvents encapsulated in SWCNTs\nare transformed to an inner tube when subject to a heat treatment under dynamic\nvacuum at 1270 $^{\\circ}$C. We used isotope labeling of the different carbon\nsources to prove that the source of the inner tubes is indeed the solvent. Our\nresults put constraints on the models explaining the inner tube growth and\nprovides a simple alternative for the fullerene based inner tube growth. It\nalso provides the possibility to study a completely new field of in-the-tube\nchemistry.",
        "positive": "Model for the catalytic oxidation of CO, including gas-phase impurities\n  and CO desorption: We present results of kinetic Monte Carlo simulations of a modified\nZiff-Gulari-Barshad model for the reaction CO+O --> CO_2 on a catalytic\nsurface. Our model includes impurities in the gas phase, CO desorption, and a\nmodification known to eliminate the unphysical O poisoned phase. The impurities\ncan adsorb and desorb on the surface, but otherwise remain inert. In a previous\nwork that did not include CO desorption [G. M. Buendia and P. A. Rikvold, Phys.\nRev. E, 85 031143 (2012)], we found that the impurities have very distinctive\neffects on the phase diagram and greatly diminish the reactivity of the system.\nIf the impurities do not desorb, once the system reaches a stationary state,\nthe CO_2 production disappears. When the impurities are allowed to desorb,\nthere are regions where the CO_2 reaction window reappears, although greatly\nreduced. Following experimental evidence that indicates that temperature\neffects are crucial in many catalytic processes, here we further analyze these\neffects by including a CO desorption rate. We find that the CO desorption has\nthe effect to smooth the transition between the reactive and the CO rich phase,\nand most importantly it can counteract the negative effects of the presence of\nimpurities by widening the reactive window such that now the system remains\ncatalytically active in the whole range of CO pressures."
    },
    {
        "anchor": "Electrotransport and magnetic properies of Cr-GaSb spintronic materials\n  synthesized under high pressure: Electrotarnsport and magnetic properties of new phases in the system Cr-GaSb\nwere studied. The samples were prepared by high-pressure (P=6-8 GPa)\nhigh-temperature treatment and identified by x-ray diffraction and scanning\nelectron microscopy (SEM). One of the CrGa$_2$Sb$_2$ phases with an\northorhombic structure $Iba2$ has a combination of ferromagnetic and\nsemiconductor properties and is potentially promising for spintronic\napplications. Another high-temperature phase is paramagnetic and identified as\ntetragonal $I4/mcm$.",
        "positive": "Imaging of Strain Driven Magnetic Domains and Strong Spin-Phonon\n  Coupling in Epitaxial Thin Films of SrRuO3: Epitaxial thin films of SrRuO3 with large strain disorder were grown using\npulsed laser deposition method which showed two distinct transition\ntemperatures in Magnetic measurements. For the first time, we present visual\nevolution of magnetic domains across the two transitions using Magnetic force\nmicroscopy on these films. The study clearly showed that the magnetic\nanisotropy corresponding to the two transitions is different. It is observed\nthat the perpendicular magnetic anisotropy is dominating in films which results\nin domain spin orientation preferably in out of plane direction. The Raman\nstudies showed that the lattice is highly influenced by the magnetic order. The\nanalysis of the phonon spectra around magnetic transition reveals the existence\nof strong spin-phonon coupling and the calculations resulted in spin-phonon\ncoupling strength ({\\lambda}) values of {\\lambda} ~ 5 cm-1 and {\\lambda} ~ 8.5\ncm-1, for SrRuO3 films grown on LSAT and SrTiO3 single crystal substrates,\nrespectively."
    },
    {
        "anchor": "Topological negative refraction of surface acoustic waves in a Weyl\n  phononic crystal: Reflection and refraction occur at interface between two different media.\nThese two fundamental phenomena form the basis of fabricating various wave\ncomponents. Specifically, refraction, dubbed positive refraction nowadays,\nappears in the opposite side of the interface normal with respect to the\nincidence. Negative refraction, emerging in the same side by contrast, has been\nobserved in artificial materials1-5 following a prediction by Veslago6, which\nhas stimulated many fascinating applications such as super-resolution imaging7.\nHere we report the first discovery of negative refraction of the topological\nsurface arc states of Weyl crystals, realized for airborne sound in a novel\nwoodpile phononic crystal. The interfaces are one-dimensional edges that\nseparate different crystal facets. By tailoring the surface terminations of\nsuch a Weyl phononic crystal, open equifrequency contours of surface acoustic\nwaves can be delicately designed to produce the negative refraction, to\ncontrast the positive counterpart realized in the same sample. Strikingly\ndifferent from the conventional interfacial phenomena, the unwanted reflection\ncan be made forbidden by exploiting the open nature of the surface\nequifrequency contours, which is a topologically protected surface hallmark of\nWeyl crystals8-12.",
        "positive": "Hydrogen Transport Between Layers of Transition Metal-Dichalcogenides: Hydrogen is a crucial source of green energy and has been extensively studied\nfor its potential usage in fuel cells. The advent of two-dimensional crystals\n(2DCs) has taken hydrogen research to new heights, enabling it to tunnel\nthrough layers of 2DCs or be transported within voids between the layers, as\ndemonstrated in recent experiments by Geim's group. In this study, we\ninvestigate how the composition and stacking of transition-metal dichalcogenide\n(TMDC) layers influence the transport and self-diffusion coefficients (D) of\nhydrogen atoms using well-tempered metadynamics simulations. Our findings show\nthat modifying either the transition metal or the chalcogen atoms significantly\naffects the free energy barriers (Delta F) and, consequently, the\nself-diffusion of hydrogen atoms between the 2DC layers. In the Hh polytype (2H\nstacking), MoSe2 exhibits the lowest Delta F, while WS2 has the highest,\nresulting in the largest D for the former system. Additionally, hydrogen atoms\ninside the RhM (or 3R) polytype encounter more than twice lower energy barriers\nand, thus, much higher diffusivity compared to those within the most stable Hh\nstacking. These findings are particularly significant when investigating\ntwisted layers or homo- or heterostructures, as different stacking areas may\ndominate over others, potentially leading to directional transport and\ninteresting materials for ion or atom sieving."
    },
    {
        "anchor": "Structure and properties of an amorphous metal--organic framework: We show that ZIF-4, a metal-organic framework (MOF) with a zeolitic\nstructure, undergoes a crystal--amorphous transition on heating to 300\n$^\\circ$C. The amorphous form, which we term a-ZIF, is recoverable to ambient\nconditions or may be converted to a dense crystalline phase of the same\ncomposition by heating to 400 $^\\circ$C. Neutron and X-ray total scattering\ndata collected during the amorphization process are used as a basis for reverse\nMonte Carlo refinement of an atomistic model of the structure of a-ZIF. We show\nthat the structure is best understood in terms of a continuous random network\nanalogous to that of a-SiO$_2$. Optical microscopy, electron diffraction and\nnanoindentation measurements reveal a-ZIF to be an isotropic glass-like phase\ncapable of plastic flow on its formation. Our results suggest an avenue for\ndesigning broad new families of amorphous and glass-like materials that exploit\nthe chemical and structural diversity of MOFs.",
        "positive": "Photon blockade and nonlinear effects for a quantum dot strongly coupled\n  to a semiconductor microcavity: Our model comprehensively simulates modern nanoscale semiconductor\nmicrocavities incorporating cavity quantum electrodynamics within both the weak\nand strong coupling regimes, using on-resonant laser excitation and nonresonant\nexcitation due to a wetting layer. For weak coupling, the most significant\neffect is photon antibunching with nonresonant emission. We investigate how the\nantibunching characteristics change as the cavity finesse is increased towards\nthe strong coupling regime. Antibunching can also be observed in a strongly\ncoupled system with resonant excitation, using the photon blockade mechanism\nwhich has been demonstrated in atom systems. We calculate what cavity\nparameters are required to observe this effect. Experimentally these studies\nare equivalent to nonlinear pump probe measurements, where a strong pump,\neither resonant or nonresonant, is used to excite the coupled system, and the\nresulting state is characterized using a weak, resonant probe beam."
    },
    {
        "anchor": "Van der Waals Heterostructure Pt$_{2}$HgSe$_{3}$/CrI$_3$ for Topological\n  Valleytronics: We identify a valley-polarized Chern insulator in the van der Waals\nheterostructure, Pt$_{2}$HgSe$_{3}$/CrI$_3$, for potential applications with\ninterplay between electric, magnetic, optical, and mechanical effects. The\ninterlayer proximity magnetic coupling nearly closes the band gap of\nPt$_{2}$HgSe$_{3}$ and the strong intra-layer spin-orbit coupling further lifts\nthe valley degeneracy by over 100 meV leading to positive and negative band\ngaps at opposite valleys. In the valley with negative gap, the interfacial\nRashba spin-orbit coupling opens a topological band gap of 17.8 meV, which is\nenlarged to 30.8 meV by adding an $h$-BN layer. We find large orbital\nmagnetization in Pt$_{2}$HgSe$_{3}$ layer that is much larger than spin, which\ncan induce measurable optical Kerr effect. The valley polarization and Chern\nnumber are coupled to the magnetic order of the nearest neighboring CrI$_3$\nlayer, which is switchable by electric, magnetic, and mechanical means in\nexperiments. The presence of $h$-BN protects the topological phase allowing the\nconstruction of superlattices with valley, spin, and layer degrees of freedoms.",
        "positive": "Interface of graphene nanopore and hexagonal boron nitride as a sensing\n  device: The atomically-precise controlled synthesis of graphene stripes embedded in\nhexagonal boron nitride opens up new possibilities for the construction of\nnanodevices with applications in sensing. Here, we explore properties related\nto electronic structure and quantum transport of a graphene nanoroad embedded\nin hexagonal boron nitride, using a combination of density functional theory\nand the non-equilibrium Green's functions method to calculate the electric\nconductance. We find that the graphene nanoribbon signature is preserved in the\ntransmission spectra and that the local current is mainly confined to the\ngraphene domain. When a properly sized nanopore is created in the graphene part\nof the system, the electronic current becomes restricted to a carbon chain\nrunning along the border with hexagonal boron nitride. This circumstance could\nallow the hypothetical nanodevice to become highly sensitive to the electronic\nnature of molecules passing through the nanopore, thus opening up ways for the\ndetection of gas molecules, amino acids, or even DNA sequences based on a\nmeasurement of the real-time conductance modulation in the graphene nanoroad."
    },
    {
        "anchor": "Energetics and stability of nanostructured amorphous carbon: Monte Carlo simulations, supplemented by ab initio calculations, shed light\ninto the energetics and thermodynamic stability of nanostructured amorphous\ncarbon. The interaction of the embedded nanocrystals with the host amorphous\nmatrix is shown to determine in a large degree the stability and the relative\nenergy differences among carbon phases. Diamonds are stable structures in\nmatrices with sp^3 fraction over 60%. Schwarzites are stable in low-coordinated\nnetworks. Other sp^2-bonded structures are metastable.",
        "positive": "Theory of excitonic spectra and entanglement engineering in dot\n  molecules: We present results of correlated pseudopotential calculations of an exciton\nin a pair of vertically stacked InGaAs/GaAs dots. Competing effects of strain,\ngeometry, and band mixing lead to many unexpected features missing in\ncontemporary models. The first four excitonic states are all optically active\nat small interdot separation, due to the broken symmetry of the single-particle\nstates. We quantify the degree of entanglement of the exciton wavefunctions and\nshow its sensitivity to interdot separation. We suggest ways to\nspectroscopically identify and maximize the entanglement of exciton states."
    },
    {
        "anchor": "Microscopic understanding of magnetic interactions in bilayer CrI$_3$: We performed the detailed microscopic analysis of the inter-layer magnetic\ncouplings for bilayer CrI$_3$. As the first step toward understanding the\nrecent experimental observations and utilizing them for device applications, we\nestimated magnetic force response as well as total energy. Various van der\nWaals functionals equivocally point to the ferromagnetic ground state for the\nlow-temperature structured bilayer CrI$_3$ which is further confirmed\nindependently by magnetic force response calculations. The calculated\norbital-dependent magnetic forces clearly show that $e_g$-$t_{2g}$ interaction\nis the key to stabilize this ferromagnetic order. By suppressing this\nferromagnetic interaction and enhancing antiferromagnetic orbital channels of\n$e_g$-$e_g$ and $t_{2g}$-$t_{2g}$, one can realize the desirable\nantiferromagnetic order. We showed that high-temperature monoclinic stacking\ncan be the case. Our results provide unique information and insight to\nunderstand the magnetism of multi-layer CrI$_3$ paving the way to utilize it\nfor applications.",
        "positive": "Highly-anisotropic elements for acoustic pentamode applications: Pentamode metamaterials are a class of acoustic metafluids that are\ncharacterized by a divergence free modified stress tensor. Such materials have\nan unconventional anisotropic stiffness and isotropic mass density, which allow\nthemselves to mimic other fluid domains. Here we present a pentamode design\nformed by an oblique honeycomb lattice and producing customizable anisotropic\nproperties. It is shown that anisotropy in the stiffness can exceed three\norders of magnitude, and that it can be realistically tailored for\ntransformation acoustic applications."
    },
    {
        "anchor": "Concentration-dependent mobility in organic field-effect transistors\n  probed by infrared spectromicroscopy of the charge density profile: We show that infrared imaging of the charge density profile in organic\nfield-effect transistors (FETs) can probe transport characteristics which are\ndifficult to access by conventional contact-based measurements. Specifically,\nwe carry out experiments and modeling of infrared spectromicroscopy of\npoly(3-hexylthiophene) (P3HT) FETs in which charge injection is affected by a\nrelatively low resistance of the gate insulators. We conclude that the mobility\nof P3HT has a power-law density dependence, which is consistent with the\nactivated transport in disorder-induced tails of the density of states.",
        "positive": "Achieving high-temperature ferromagnetism by means of magnetic ions\n  dimerization: Magnetic two-dimensional materials have potential application in\nnext-generation electronic devices and have stimulated extensive interest in\ncondensed matter physics and material fields. However, how to realize\nhigh-temperature ferromagnetism in two-dimensional materials remains a great\nchallenge in physics.\n  Herein, we propose an effective approach that the dimerization of magnetic\nions in two-dimensional materials can enhance the exchange coupling and\nstabilize the ferromagnetism.\n  Manganese carbonitride Mn$_2$N$_6$C$_6$ with a planar monolayer structure is\ntaken as an example to clarify the method, in which two Mn atoms are gathered\ntogether to form a ferromagnetic dimer of Mn atoms and further these dimers are\ncoupled together to form the overall ferromagnetism of the two-dimensional\nmaterial.\n  In Mn$_2$N$_6$C$_6$ monolayer, the near-room-temperature ferromagnetism with\nthe Curie temperature of 272.3 K is determined by solving Heisenberg model\nusing Monte Carlo simulations method."
    },
    {
        "anchor": "Transfer Characteristics in Graphene Field-Effect Transistors with Co\n  Contacts: Graphene field-effect transistors with Co contacts as source and drain\nelectrodes show anomalous distorted transfer characteristics. The anomaly\nappears only in short-channel devices (shorter than approximately 3\nmicrometers) and originates from a contact-induced effect. Band alteration of a\ngraphene channel by the contacts is discussed as a possible mechanism for the\nanomalous characteristics observed.",
        "positive": "Topological Constraints and Rigidity of Network Glasses from Molecular\n  Dynamics Simulations: Due to its non-crystalline nature, the glassy state has remained one the most\nexciting scientific challenges. To study such materials, Molecular Dynamics\n(MD) simulations have been extensively used because they provide a direct view\ninto its microscopic structure. MD is therefore used not only to reproduce real\nsystem properties but also benefits from detailed atomic scale analysis.\nUnfortunately, MD shows inherent limitations because of the limited\ncomputational power. For instance, only the simulations of small systems are\ncurrently permitted, which prevents from studying small compositional changes,\nalthough it is well known that they can dramatically alter system properties.\nAt this stage, it is tempting to follow topological constraint theory, which\naims at describing macroscopic properties of the glass relying only on the\nconnectivity of individual atoms, thus considering the complicated glass\nnetwork as simple mechanical trusses. Thanks to only basic hand calculations,\nthis theory has been successful in predicting complex composition and\ntemperature behavior of glass properties, such as the glass forming ability,\nthe viscosity of the corresponding liquid or the elasticity. The purpose of my\nPhD work is to connect these successful approaches based only on the topology\nof the underlying low-temperature network with properties that can be obtained\nfrom MD calculations. It should thus allow for an increased applicability of\nrigidity theory."
    },
    {
        "anchor": "Complete crystal field calculation of Zeeman-hyperfine splittings in\n  europium: Computational crystal-field models have provided consistent models of both\nelectronic and Zeeman-hyperfine structure for several rare earth ions. These\ntechniques have not yet been applied to the Zeeman-hyperfine structure of\nEu$^{3+}$ because modeling the structure of the $J=0$ singlet levels in\nEu$^{3+}$ requires inclusion of the commonly omitted lattice electric\nquadrupole and nuclear Zeeman interactions. Here, we include these terms in a\ncomputational model to fit the crystal field levels and the Zeeman-hyperfine\nstructure of the $^7F_0$ and $^5D_0$ states in three Eu$^{3+}$ sites: the\nC$_{4v}$ and C$_{3v}$ sites in CaF$_2$ and the C$_2$ site in EuCl$_3$.6H$_2$O.\nClose fits are obtained for all three sites which are used to resolve\nambiguities in previously published parameters, including quantifying the\nanomalously large crystal-field-induced state mixing in the C$_{3v}$ site and\ndetermining the signs of Zeeman-hyperfine parameters in all three sites. We\nshow that this model allows accurate prediction of properties for Eu$^{3+}$\nimportant for quantum information applications of these ions, such as relative\ntransition strengths. The model could be used to improve crystal field\ncalculations for other non-Kramers singlet states. We also present a spin\nHamiltonian formalism without the normal assumption of no $J$ mixing, suitable\nfor other rare earth ion energy levels where this effect is important.",
        "positive": "Experimental and computational approaches to study the high temperature\n  thermoelectric properties of novel topological semimetal CoSi: Here, we study the thermoelectric properties of topological semimetal CoSi in\nthe temperature range $300-800$ K by using combined experimental and density\nfunctional theory (DFT) based methods. CoSi is synthesized using arc melting\ntechnique and the Rietveld refinement gives the lattice parameters of a = b = c\n= 4.445 {\\AA}. The measured values of Seebeck coefficient (S) shows the\nnon-monotonic behaviour in the studied temperature range with the value of\n$\\sim-$81 $\\mu$V/K at room temperature. The $|S|$ first increases till 560 K\n($\\sim-$93 $\\mu$V/K) and then decreases up to 800 K ($\\sim-$84 $\\mu$V/K)\nindicating the dominating n-type behaviour in the full temperature range. The\nelectrical conductivity, $\\sigma$ (thermal conductivity, $\\kappa$) shows the\nmonotonic decreasing (increasing) behaviour with the values of $\\sim$5.2$\\times\n10^{5}$ (12.1 W/m-K) and $\\sim$3.6$\\times 10^{5}$ (14.2 W/m-K)\n$\\Omega^{-1}m^{-1}$ at 300 K and 800 K, respectively. The $\\kappa$ exhibits the\ntemperature dependency as, $\\kappa \\propto T^{0.16}$. The DFT based Boltzmann\ntransport theory is used to understand these behaviour. The multi-band electron\nand hole pockets appear to be mainly responsible for deciding the temperature\ndependent transport behaviour. Specifically, the decrease in the $|S|$ above\n560 K and change in the slope of $\\sigma$ around 450 K are due to the\ncontribution of thermally generated charge carriers from the hole pockets. The\ntemperature dependent relaxation time is computed which shows temperature\ndependency of $1/T^{0.35}$. Present study suggests that electronic\nband-structure obtained from DFT provides reasonably good estimate of the\ntransport coefficients of CoSi in the high temperature region of $300-800$ K."
    },
    {
        "anchor": "Anisotropic Compression in Dimer C60 Fullerene Solid: Dimer C60 solids are monoclinic crystals with molecular longer axis aligned\nalong the c-axis. A simple model based on atom-atom potential used to calculate\nvarious bulk, structural and thermodynamic properties of this fullerite, has\nalso been used to investigate the pressure and temperature dependent properties\nsuch as bulk modulus, lattice and orientational structure, phonon dispersion\nrelations, Gruneisen parameters, heat capacity and entropy. An important\nfeature of this solid evidently concerns its anisotropic pressure compression.\nWe calculate these directional compressibilities and find the anisotropy for\npressure compression very significant. It is expected that the properties of\ndimer solid C60 calculated here will motivate further experimentation on this\nsolid.",
        "positive": "A numerical study of the effect of discretization methods on the crystal\n  plasticity finite element method: The present report describes a big data numerical study of crystal plasticity\nfinite element (CPFE) modelling using static and grain-based meshing to\ninvestigate the dependence of the results on the discretization approach.\nStatic mesh refers to the integration point-based representation of the\nmicrostructure in which the integration points (IPs) within a finite element\nmay belong to different grains, while in the grain-based meshing the minimum\ndiscretization unit is an element that may only belong to one grain. The\ncrystal plasticity constitutive law was coded using UMAT subroutine within\ncommercial finite element software Abaqus. Multiple sets of RVEs were\ninvestigated under strain-controlled loading and periodic boundary conditions.\nThe stress and strain contour maps obtained from RVEs with static mesh and\ngrain-based mesh were compared. The simulation results reveal that both\ndiscretization methods provide reliable predictions of the stress-strain curves\nand the stress/strain localization points in polycrystalline alloys. Static\nmesh tends to smooth the stress/strain profile at the grain boundary, whilst\nstress/strain discontinuities are present in the grain-based mesh results. The\nabove findings remain valid when the number of grains within an RVE increases\nfrom 34 to 1250. To quantify the difference between static and grain-based\nmeshing, a relative measure of deviation is defined. The deviations of global\nstress were found to be relatively small, within 0.5%, while local deviations\nwere significant up to 50%. Static mesh has the advantage of reducing both the\npreprocessing procedures and computational time compared to grain-based mesh.\nIt is concluded that static mesh is preferred when investigating the material's\nmacroscopic behaviour, whilst grain-based mesh is recommended for the study of\nthe local response using CPFEM."
    },
    {
        "anchor": "Broad-band dielectric response of BTZ-BCT piezoceramics: soft and\n  central mode behaviour: Dielectric properties of BTZ-BCT ceramics were probed in the frequency range\nfrom 10 Hz to 100 THz in a broad temperature range (10-900 K). Polar soft\nphonon observed in infrared spectra softens with cooling, however below 500 K\nits frequency becomes temperature independent. Simultaneously, a central mode\nactivates in terahertz and microwave spectra; and it actually drives the\nferroelectric phase transitions. Consequently, the phase transition strongly\nresemble a crossover between the dispacive and order-disorder type. The central\nmode vanishes below 200 K. The dielectric relaxation in the radiofrequency and\nmicrowave range anomalously broadens on cooling below T$_{C1}$ resulting in the\nnearly frequency independent dielectric loss bleow 200 K. This broadening comes\nfrom a broad frequency distribution of ferroelectric domain wall vibrations.\nRaman spectra reveal new phonons below 400 K, i.e. already 15 K above T$_{C1}$.\nSeveral weak modes are detected in the paraelectric phase up to 500 K in the\nRaman spectra. Activation of these modes is ascribed to the presence of polar\nnanoclusters in the material.",
        "positive": "Robust evidence for the stabilization of the premartensite phase in\n  Ni-Mn-In magnetic shape memory alloys by chemical pressure: The thermodynamic stability of the premartensite (PM) phase has been a topic\nof extensive investigation in shape memory alloys as it affects the main\nmartensite phase transition and the related physical properties. In general,\nthe PM phase is stable over a rather narrow temperature-composition range. We\npresent here evidence for chemical pressure induced suppression of the main\nmartensite transition and stabilization of the PM phase over a very wide\ntemperature range from 300 K to around 5 K in a magnetic shape memory alloy\n(MSMA) Ni50Mn34In16 using magnetic susceptibility, synchrotron X-ray powder\ndiffraction (SXRPD) studies and first-principles calculations. The\nac-susceptibility studies show a highly skewed and smeared peak around 300 K\nwithout any further transition up to the lowest temperature of our measurement\n(5 K) for around 5% Al substitution. The temperature evolution of the SXRPD\npatterns confirms the appearance of the PM phase related satellite peaks at and\nbelow 300 K without any splitting of the main austenite (220) peak showing\npreserved cubic symmetry. This is in marked contrast to the temperature\nevolution of the SXRPD patterns of the martensite phase of the Al free as well\nas around 3% Al substituted compositions where the austenite (220) peak shows a\nclear splitting due to Bain distortion/symmetry breaking transition. Our\ntheoretical calculations support the experimental findings and reveal that the\nsubstitution at the In site by a smaller size atom, like Al, can stabilize the\nPM phase with preserved cubic symmetry. Our results demonstrate that\nAl-substituted Ni-Mn-In MSMAs provide an ideal platform for investigating the\nphysics of various phenomena related to the PM state."
    },
    {
        "anchor": "Electron spin relaxation in GaAs$_{1-x}$Bi$_x$: Effects of spin-orbit\n  tuning by Bi incorporation: The electron spin relaxation in $n$-type and intrinsic GaAs$_{1-x}$Bi$_x$\nwith Bi composition $0\\le x \\le 0.1$ is investigated from the microscopic\nkinetic spin Bloch equation approach. The incorporation of Bi is shown to\nmarkedly decrease the spin relaxation time as a consequence of the modification\nof the spin-orbit interaction. We demonstrate that the density and temperature\ndependences of spin relaxation time in GaAs$_{1-x}$Bi$_x$ resemble the ones in\nGaAs. Meanwhile, the Bir-Aronov-Pikus mechanism is found to be negligible\ncompared to the D'yakonov-Perel' mechanism in intrinsic sample. Due to the\nabsence of direct measurement of the electron effective mass in the whole\ncompositional range under investigation, we further explore the effect of a\npossible variation of electron effective mass on the electron spin relaxation.",
        "positive": "Electronic band structure of narrow-bandgap p-n nanojunctions in\n  heterostructured nanowires measured by electron energy loss spectroscopy: The electronic band structure of complex nanostructured semiconductors has a\nconsiderable effect on the final electronic and optical properties of the\nmaterial and, ultimately, on the functionality of the devices incorporating\nthem. Valence electron energy-loss spectroscopy (VEELS) in the transmission\nelectron microscope (TEM) provides the possibility of measuring this property\nof semiconductors with high spatial resolution. However, it still represents a\nchallenge for narrow-bandgap semiconductors, since an electron beam with low\nenergy spread is required. Here we demonstrate that by means of monochromated\nVEELS we can study the electronic band structure of narrow-gap materials GaSb\nand InAs in the form of heterostructured nanowires, with bandgap values down to\n0.5 eV, especially important for newly developed structures with unknown\nbandgaps. Using complex heterostructured InAs-GaSb nanowires, we determine a\nbandgap value of 0.54 eV for wurtzite InAs. Moreover, we directly compare the\nbandgaps of wurtzite and zinc-blende polytypes of GaSb in a single\nnanostructure, measured here as 0.84 and 0.75 eV, respectively. This allows us\nto solve an existing controversy in the band alignment between these structures\narising from theoretical predictions. The findings demonstrate the potential of\nmonochromated VEELS to provide a better understanding of the band alignment at\nthe heterointerfaces of narrow-bandgap complex nanostructured materials with\nhigh spatial resolution. This is especially important for semiconductor device\napplications where even the slightest variations of the electronic band\nstructure at the nanoscale can play a crucial role in their functionality."
    },
    {
        "anchor": "Magnetic characterization of the frustrated three-leg ladder compound\n  [(CuCl2tachH)3Cl]Cl2: We report the magnetic features of a new one-dimensional stack of\nantiferromagnetically coupled equilateral copper(II) triangles. High-field\nmagnetization measurements show that the interaction between the copper\ntriangles is of the same order of magnitude as the intra-triangle exchange\nalthough only coupled via hydrogen bonds. The infinite chain turns out to be an\ninteresting example of a frustrated cylindrical three-leg ladder with competing\nintra- and inter-triangle interactions. We demonstrate that the ground state is\na spin singlet which is gaped from the triplet excitation.",
        "positive": "Evaluation of microscale crystallinity modification induced by laser\n  writing on Mn3O4 thin films: Defining microstructures and managing local crystallinity allow the\nimplementation of several functionalities in thin film technology. The use of\nultrashort Bessel beams for bulk crystallinity modification has garnered\nconsiderable attention as a versatile technique for semiconductor materials,\ndielectrics, or metal oxide substrates. The aim of this work is the\nquantitative evaluation of the crystalline changes induced by ultrafast laser\nmicromachining on manganese oxide thin films using micro-Raman spectroscopy.\nPulsed Bessel beams featured by a 1 micrometer-sized central core are used to\ndefine structures with high spatial precision. The dispersion relation of Mn3O4\noptical phonons is determined by considering the conjunction between X-ray\ndiffraction characterization and the phonon localization model. The asymmetries\nin Raman spectra indicate phonon localization and enable a quantitative tool to\ndetermine the crystallite size at micrometer resolution. The results indicate\nthat laser-writing is effective in modifying the low-crystallinity films\nlocally, increasing crystallite sizes from ~8 nm up to 12 nm, and thus\nhighlighting an interesting approach to evaluate laser-induced structural\nmodifications on metal oxide thin films."
    },
    {
        "anchor": "Self-Consistent Green Function Embedding for Advanced Electronic\n  Structure Methods Based on a Dynamical Mean-Field Concept: We present an embedding scheme for periodic systems that facilitates the\ntreatment of the physically important part (here the unit cell) with advanced\nelectronic-structure methods, that are computationally too expensive for\nperiodic systems. The rest of the periodic system is treated with\ncomputationally less demanding approaches, e.g., Kohn-Sham density-functional\ntheory, in a self- consistent manner. Our scheme is based on the concept of\ndynamical mean-field theory (DMFT) formulated in terms of Green functions. In\ncontrast to the original DMFT formulation for correlated model Hamiltonians, we\nhere consider the unit cell as local embedded cluster in a first-principles\nway, that includes all electronic degrees of freedom. Our real-space dynamical\nmean-field embedding (RDMFE) scheme features two nested Dyson equations, one\nfor the embedded cluster and another for the periodic surrounding. The total\nenergy is computed from the resulting Green functions. The performance of our\nscheme is demonstrated by treating the embedded region with hybrid functionals\nand many-body perturbation theory in the GW approach for simple bulk systems.\nThe total energy and the density of states converge rapidly with respect to the\ncomputational parameters and approach their bulk limit with increasing cluster\n(i.e., unit cell) size.",
        "positive": "The effect of transverse magnetic correlations on a coupled order\n  parameter: shifted transition temperatures and thermal hysteresis: We use a Green's function method with Random Phase Approximation to show how\nmagnetic correlations may affect electric polarization in multiferroic\nmaterials with magnetic-exchange-type magnetoelectric coupling. We use a model\nspin 1/2 ferromagnetic ferroelectric system but our results are expected to\napply to multiferroic materials with more complex magnetic structures. In\nparticular, we find that transverse magnetic correlations result in a change in\nthe free energy of the ferroelectric solutions leading to the possibility for\nthermal hysteresis of the electric polarization above the magnetic Curie\ntemperature. Although we are motivated by multiferroic materials, this problem\nrepresents a more general calculation of the effect of fluctuations on coupled\norder parameters."
    },
    {
        "anchor": "Initiation and Propagation of Plastic Yielding in Duplex Stainless Steel: The elastoplastic behavior of a two-phase stainless steel alloy is explored\nat the crystal scale for five levels of stress biaxiality. The crystal lattice\n(elastic) strains were measured with neutron diffraction using tubular samples\nsubjected to different combinations of axial load and internal pressure to\nachieve a range of biaxial stress ratios. Finite element simulations were\nconducted on virtual polycrystals using loading histories that mimicked the\nexperimental protocols. For this, two-phase microstructures were instantiated\nbased on microscopy images of the grain and phase topologies and on\ncrystallographic orientation distributions from neutron diffraction. Detailed\ncomparisons were made between the measured and computed lattice strains for\nseveral crystal reflections in both phases for scattering vectors in the axial,\nradial and hoop directions that confirm the model's ability to accurate predict\nthe evolving local stress states. A strength-to-stiffness parameter for\nmultiaxial stress states was applied to explain the initiation of yielding\nacross the polycrystalline samples across the five levels of stress biaxiality.\nFinally, building off the multiaxial strength-to-stiffness, the propagation of\nyielding over the volume of a polycrystal was estimated in terms of an equation\nthat provides the local stress necessary to initiate within crystals in terms\nof the macroscopic stress.",
        "positive": "Granular Pressure and the Thickness of a Layer Jamming on a Rough\n  Incline: Dense granular media have a compaction between the random loose and random\nclose packings. For these dense media the concept of a granular pressure\ndepending on compaction is not unanimously accepted because they are often in a\n\"frozen\" state which prevents them to explore all their possible microstates, a\nnecessary condition for defining a pressure and a compressibility\nunambiguously. While periodic tapping or cyclic fluidization have already being\nused for that exploration, we here suggest that a succession of flowing states\nwith velocities slowly decreasing down to zero can also be used for that\npurpose. And we propose to deduce the pressure in \\emph{dense and flowing}\ngranular media from experiments measuring the thickness of the granular layer\nthat remains on a rough incline just after the flow has stopped."
    },
    {
        "anchor": "Direct observation of local Mn-Mn distances in the paramagnetic compound\n  CsMnxMg1-xBr3: We introduce a novel method for local structure determination with a spatial\nresolution of the order of 0.01 Angstroem. It can be applied to materials\ncontaining clusters of exchange-coupled magnetic atoms. We use neutron\nspectroscopy to probe the energies of the cluster excitations which are\ndetermined by the interatomic coupling strength J. Since for most materials J\nis related to the interatomic distance R through a linear relation\ndJ/dR={\\alpha} (for dR/R<<1), we can directly derive the local distance R from\nthe observed excitation energies. This is exemplified for the mixed\none-dimensional paramagnetic compound CsMnxMg1 xBr3 (x=0.05, 0.10) containing\nmanganese dimers oriented along the hexagonal c-axis. Surprisingly, the\nresulting Mn-Mn distances R do not vary continuously with increasing internal\npressure, but lock in at some discrete values.",
        "positive": "Crystal structure of solid Oxygen at high pressure and low temperature: Results of X-ray diffraction experiments on solid oxygen at low temperature\nand at pressures up to 10 GPa are presented.A careful sample preparation and\nannealing around 240 K allowed to obtain very good diffraction patterns in the\northorhombic delta-phase. This phase is stable at low temperature, in contrast\nto some recent data [Y. Akahama et al., Phys. Rev. B64, 054105 (2001)], and\ntransforms with decreasing pressure into a monoclinic phase, which is\nidentified as the low pressure alpha-phase. The discontinuous change of the\nlattice parameters, and the observed metastability of the alpha-phase\nincreasing pressure suggest that the transition is of the first order."
    },
    {
        "anchor": "Finite-temperature magnetism of Fe$_x$Pd$_{1-x}$ and Co$_x$Pt$_{1-x}$\n  alloys: The finite-temperature magnetic properties of Fe$_x$Pd$_{1-x}$ and\nCo$_x$Pt$_{1-x}$ alloys have been investigated. It is shown that the\ntemperature-dependent magnetic behaviour of alloys, composed of originally\nmagnetic and non-magnetic elements, cannot be described properly unless the\ncoupling between magnetic moments at magnetic atoms (Fe,Co) mediated through\nthe interactions with induced magnetic moments of non-magnetic atoms (Pd,Pt) is\nincluded. A scheme for the calculation of the Curie temperature ($T_C$) for\nthis type of systems is presented which is based on the extended Heisenberg\nHamiltonian with the appropriate exchange parameters $J_{ij}$ obtained from\n{\\em ab-initio} electronic structure calculations. Within the present study the\nKKR Green's function method has been used to calculate the $J_{ij}$ parameters.\nA comparison of the obtained Curie temperatures for Fe$_x$Pd$_{1-x}$ and\nCo$_x$Pt$_{1-x}$ alloys with experimental data shows rather good agreement.",
        "positive": "Autocatalytic MBE growth of GaAs nanowires on oxidized Si(100): GaAs nanowires were grown by molecular beam epitaxy on Si(100) substrates\ncovered with 5 nm SiO2. The growth was performed with As4 at low, close to\nstoichiometric, As4/Ga flux ratio, using Ga nanodroplets as catalyst. The\nnanowires are found to be in epitaxial relation to the Si substrate due to\ncontact via pinholes through the SiO2 layer. The nanowires are up to 15\nmicrometers long and have diameters of about 100 nm, the catalyzing Ga\nnanodroplets are observed at their tops."
    },
    {
        "anchor": "The Jellium Edge and the Size Effect of the Chemical Potential and\n  Surface Energy in Metal Slabs: Although free electron models have been established in order to capture the\nessential physics of interfacial and bulk properties in metals, some issues\nstill remain regarding the application of free electron models to thin metal\nfilms. One of the issues relates to whether the geometric edge coincides with\nthe potential edge in order to satisfy the charge neutrality condition when the\npotential profile is modeled as a rectangular potential well. We show that they\ncoincide by rigorously taking into account the quantization effect arising from\nelectron confinement in a thin metal slab. As a result, the overall behaviors\nof the chemical potential and surface energy show an increasing trend by\ndecreasing the thickness of the slab. The chemical potential and surface energy\nshow an oscillatory thickness dependence by further taking into account the\ndiscreteness of the total number of free electrons.",
        "positive": "Anomalous thermoelectric effects and quantum oscillations in the kagome\n  metal CsV$_3$Sb$_5$: The kagome metal compounds $A$V$_3$Sb$_5$ ($A$ = K, Rb, and Cs) feature a\nwealth of phenomena including nontrivial band topology, charge density wave\n(CDW), and superconductivity. One intriguing property is the time-reversal\nsymmetry breaking in the CDW state without local moments, which leads to\nanomalous transport responses. Here, we report the investigation of\nmagneto-thermoelectric effects on high-quality CsV$_3$Sb$_5$ single crystals. A\nlarge anomalous Nernst effect is observed at temperatures below 30 K. Multiple\nFermi surfaces with small effective masses are revealed by quantum oscillations\nin Nernst and Seebeck signals under high magnetic field. Furthermore, we find\nan unknown frequency, and attribute it to the magnetic breakdown across two\nsmaller Fermi surfaces. A gap around 20 meV can be resolved from the breakdown\nthreshold field, which we propose to be introduced by the CDW. These results\nshed new light on the CDW-related phenomena, particularly in $A$V$_3$Sb$_5$\ncompounds."
    },
    {
        "anchor": "Density functional calculations for III-V diluted ferromagnetic\n  semiconductors: A Review: In this paper we review the latest achievements of density functional theory\nin understanding the physics of diluted magnetic semiconductors. We focus on\ntransition metal doped III-V semiconductors, which show spontaneous\nferromagnetic order at relatively high temperature and good structural\ncompatibility with existing III-V devices. We show that density functional\ntheory is a very powerful tool for i) studying the effects of local doping\ndefects and disorder on the magnetic properties of these materials, ii)\npredicting properties of new materials and iii) providing parameters, often not\naccessible from experiments, for use in model Hamiltonian calculations. Such\nstudies are facilitated by recent advances in numerical implementations of\ndensity functional theory, which make the study of systems with a very large\nnumber of atoms possible.",
        "positive": "Strain-Induced Polarization Enhancement in BaTiO$_3$ Core-Shell\n  Nanoparticles: Despite fascinating experimental results, the influence of defects and\nelastic strains on the physical state of nanosized ferroelectrics is still\npoorly explored theoretically. One of unresolved theoretical problems is the\nanalytical description of the strongly enhanced spontaneous polarization,\npiezoelectric response, and dielectric properties of ferroelectric oxide thin\nfilms and core-shell nanoparticles induced by elastic strains and stresses. In\nparticular, the 10-nm quasi-spherical BaTiO3 core-shell nanoparticles reveal a\ngiant spontaneous polarization up to 130 mu_C/cm2, where the physical origin is\na large Ti off-centering. The available theoretical description cannot explain\nthe giant spontaneous polarization observed in these spherical nanoparticles.\nThis work analyzes polar properties of BaTiO3 core-shell spherical\nnanoparticles using the Landau-Ginzburg-Devonshire approach, which considers\nthe nonlinear electrostriction coupling and large Vegard strains in the shell.\nWe reveal that a spontaneous polarization greater than 50 mu_C/cm2 can be\nstable in a (10-100) nm BaTiO3 core at room temperature, where a 5 nm\nparaelectric shell is stretched by (3-6)% due to Vegard strains, which\ncontribute to the elastic mismatch at the core-shell interface. The\npolarization value 50 mu_C/cm2 corresponds to high tetragonality ratios (1.02 -\n1.04), which is further increased up to 100 mu_C/cm2 by higher Vegard strains\nand/or intrinsic surface stresses leading to unphysically high tetragonality\nratios (1.08 - 1.16). The nonlinear electrostriction coupling and the elastic\nmismatch at the core-shell interface are key physical factors of the\nspontaneous polarization enhancement in the core. Doping with the\nhighly-polarized core-shell nanoparticles can be useful in optoelectronics and\nnonlinear optics, electric field enhancement, reduced switching voltages,\ncatalysis, and electrocaloric nanocoolers."
    },
    {
        "anchor": "Unravelling the interplay of geometrical, magnetic and electronic\n  properties of metal-doped graphene nanomeshes: Graphene nanomeshes (GNMs), formed by creating a superlattice of pores in\ngraphene, possess rich physical and chemical properties. Many of these\nproperties are determined by the pore geometry. In this work, we use first\nprinciples calculations to study the magnetic and electronic properties of\nmetal-doped nitrogen-passivated GNMs. We find that the magnetic behaviour is\ndependent on the pore shape (trigonal vs. hexagonal) as dictated by the number\nof covalent bonds formed between the 3$d$ metal and the passivating N atoms. We\nalso find that Cr and V doped trigonal-pore GNMs, and Ti doped GNMs are the\nmost favourable for spintronic applications. The calculated magnetic properties\nof Fe-doped GNMs compare well with recent experimental observations. The\nstudied systems are useful as spin filters and chemical sensors.",
        "positive": "A calculation method to estimate thermal conductivity of high entropy\n  ceramic for thermal barrier coatings: High entropy ceramics are highly promising as next generation thermal barrier\ncoatings due to their unique disorder structure, which imparts ultra-low\nthermal conductivity and good high temperature stability. Unlike traditional\nceramic materials, the thermal resistance in high entropy ceramics\npredominantly arises from phonon-disorder scattering rather than phonon-phonon\ninteractions. In this study, we propose a calculation method based on the\nsupercell phonon unfolding (SPU) technique to predict the thermal conductivity\nof high entropy ceramics, specially focusing on rocksalt oxides structures. Our\nprediction method relies on using the reciprocal value of SPU phonon spectra\nlinewidth as an indicator of phonon lifetime. The obtained results demonstrate\na strong agreement between the predicted thermal conductivities and the\nexperimental measurements, validating the feasibility of our calculation\nmethod. Furthermore, we extensively investigate and discuss the atomic\nrelaxation and lattice distortion effects in 5-dopants and 6-dopants rocksalt\nstructures during the process."
    },
    {
        "anchor": "Spin-orbit driven terahertz optical response in ferromagnetic Fe-Co-Al\n  alloys: We study the magneto-optical properties of Fe-Co-Al ordered alloys in the\nterahertz range of frequencies. We find that magnetism can modify the\nreflection of light from these magnets and that this modification strongly\ndepends on the frequency of incoming light in the terahertz range. For example,\nwe find that below 10~THz Co$_3$Al has nearly constant $\\sigma_{xy}$ and that\nabove 10~THz it is reduced by about 50 times. Furthermore, we find a strong\ndependence of $\\sigma_{xy}$ on chemical composition. For example, we find that\nthe addition of Al to Fe changes the sign of $\\sigma_{xy}$, while the addition\nof Co to Fe leads to non-monotonic dependence of $\\sigma_{xy}$ on\nCo-concentration.",
        "positive": "Possible Localization Behavior of the Inherent Conducting Polymer\n  (CH$_3$)$_{0.9}$ReO$_3$: Polymeric methyltrioxorhenium (poly-MTO) represents the first example of an\ninherent conducting organometallic oxide. It adopts the structural motives and\ntransport properties of some classical perovskites in two dimensions. In this\nstudy we present resistivity data down to 30 mK which exhibit a crossover from\na metallic (d$\\rho$/d$T >$ 0) to an insulating (d$\\rho$/d$T <$ 0) behavior at\nabout 30 K. Below 30 K an unusual resistivity behavior, similar to that of some\ndoped cuprate systems, is observed: initially the resistivity increases\napproximately as $\\rho \\sim$ log$(1/T$) before it starts to saturate below 2 K.\nFurthermore, a linear positive magnetoresistance is found (up to 7 T).\nTemperature dependent magnetization and specific heat measurements in various\nmagnetic fields indicate that the unusual resistivity behavior may be driven by\nspatial localization of the d$^1$ moments at the Re atoms."
    },
    {
        "anchor": "Quasiparticle Calculations for Point Defects on Semiconductor Surfaces: We discuss the implementation of quasiparticle calculations for point defects\non semiconductor surfaces and, as a specific example, present an ab initio\nstudy of the electronic structure of the As vacancy in the +1 charge state on\nthe GaAs(110) surface. The structural properties are calculated with the\nplane-wave pseudopotential method, and the quasiparticle energies are obtained\nfrom Hedin's GW approximation. Our calculations show that the 1a\" vacancy state\nin the band gap is shifted from 0.06 to 0.65 eV above the valence-band maximum\nafter the self-energy correction to the Kohn-Sham eigenvalues. The GW result is\nin close agreement with a recent surface photovoltage imaging measurement.",
        "positive": "Gas Sensing Properties of single-material SnP3 logical junction via\n  Negative Differential Resistance: Theoretical Study: The field of 2D materials has gained a lot of attention for vast range of\napplications. Amongst others, the sensing ability towards harmful gases is the\napplication, which we explored in the present work using quantum-mechanical\nsimulations for the SnP3 material. Its electronic properties, namely 1 and 2\nlayers being semiconducting, while multilayers being metallic, offer a\npossibility to build a single-material logical junction. In addition, the\nharmful gases studied here show physical adsorption with charge transfer from\nthe substrate to the gas molecules. Calculated recovery times show promise of a\ngood sensing material. The I-V characteristics calculated for all cases\nindicates that SnP3 could be a viable sensing material towards NO gas via\nnegative differential resistance."
    },
    {
        "anchor": "Structure-Dynamics Relationship in Al-Mg-Si Liquid Alloys: Enhancing properties and performances of aluminium alloys by a control of\ntheir solidification is pivotal in automotive and aerospace industries. The\nfundamental role of the structure-diffusion relationship is investigated for\nAl-Mg-Si liquid alloys taken as a prototype of Al-6xxx. For this purpose, first\nprinciples-based molecular dynamics simulations were performed for various Si\nand Mg content for Al-rich compositions, including the binary alloy\ncounterparts. Results indicate that Mg and/or Si in alloys create a more\ncompact ordering around Al than in pure Al, lowering diffusion. Mg promotes\nicosahedral short-range order, while Si displays a preference towards cubic\nlocal ordering, impacting diffusion based on their respective content. It\nsuggests a mechanism whereby an increase in Mg content generally lowers the\ndiffusion of each species, whereas an increase in Si content enhances their\ndiffusion, providing insights for future alloy design.",
        "positive": "Room-temperature intrinsic ferromagnetism of two-dimensional Na2Cl\n  crystals originated by s- and p-orbitals: Ferromagnetism, as one of the most valuable properties of materials, has\nattracted sustained and widespread interest in basic and applied research from\nancient compasses to modern electronic devices. Traditionally, intrinsic\nferromagnetism has been attributed to the permanent magnetic moment induced by\npartially filled d- or f-orbitals. However, the development of ferromagnetic\nmaterials has been limited by this electronic structure convention. Thus, the\nidentification of additional materials that are not constrained by this\nconventional rule but also exhibit intrinsic ferromagnetism is highly expected\nand may impact all the fields based on ferromagnetism. Here, we report the\ndirect observation of room-temperature intrinsic ferromagnetism in\ntwo-dimensional (2D) Na2Cl crystals, in which there are only partially filled\ns- and p-orbitals rather than d- or f-orbitals, using the superconducting\nquantum interference device (SQUID) and magnetic force microscope (MFM). These\nNa2Cl crystals formed in reduced graphene oxide (rGO) membranes have an\nunconventional stoichiometric structure leading to unique electron and spin\ndistributions. And the structure of these 2D Na2Cl crystals, including the Na\nand Cl sites, is characterized in situ for the first time and directly observed\nby cryo-electron microscopy (cryo-EM) based on the observed difference in\ncontrast between Na stacked with Cl and single Na. These findings break the\nconventional rule of intrinsic ferromagnetism and provide new insights into the\ndesign of novel magnetic and electronic devices and transistors with a size\ndown to the atomic scale."
    },
    {
        "anchor": "Strain effects on work functions of pristine and potassium-decorated\n  carbon nanotubes: Strain dependence of electronic structures and work functions of both\npristine and potassium doped (5,5) (armchair) and (9,0) (zigzag) carbon\nnanotubes (CNTs) has been thoroughly studied using first-principles\ncalculations based on density functional theory (DFT). We found that for\npristine cases, the uniaxial strain has strong effects on work functions of\nCNTs, and the responses of work functions of CNT (5,5) and (9,0) to the strain\nare distinctly different. When the strain changes from -10% to +10%, the work\nfunction of the CNT (5,5) increases monotonically from 3.95 eV to 4.57 eV, and\nthe work function of the (9,0) varies between 4.27 eV and 5.24 eV in a\ncomplicated manner. When coated with potassium, for both CNTs, work functions\ncan be lowered down by more than 2.0 eV, and the strain dependence of work\nfunctions changes drastically. Our studies suggested that the combination of\nchemical coating and tuning of strain may be a powerful tool for controlling\nwork functions of CNTs, which in turn will be useful in future design of\nCNT-based electronic and field-emitting devices.",
        "positive": "On the dynamics of curved dislocation ensembles: To develop a dislocation-based statistical continuum theory of crystal\nplasticity is a major challenge of materials science.During the last two\ndecades such a theory has been developed for the time evolution of a system of\nparallel edge dislocations. The evolution equations were derived by a\nsystematic coarse-graining of the equations of motion of the individual\ndislocations and later retrieved from a functional of the dislocation densities\nand the stress potential by applying the standard formalism of phase field\ntheories. It is, however, a long standing issue if a similar procedure can be\nestablished for curved dislocation systems. An important prerequisite for such\na theory has recently been established through a density-based kinematic theory\nof moving curves. In this paper, an approach is presented for a systematic\nderivation of the dynamics of systems of curved dislocations in a single slip\nsituation. In order to reduce the complexity of the problem a dipole like\napproximation for the orientation dependent density variables is applied. This\nleads to a closed set of kinematic evolution equations of total dislocation\ndensity, the GND densities, and the so-called curvature density. The analogy of\nthe resulting equations with the edge dislocation model allows one to\ngeneralize the phase field formalism and to obtain a closed set of dynamic\nevolution equations."
    },
    {
        "anchor": "Low energy Ar$^{+}$ ion beam induced kinetic roughening of thin Pt films\n  on a Si substrate: A 30 nm Pt thin film evaporated onto a Si wafer was sputtered by 8 keV\nAr$^{+}$ ions at various ion doses. The evolution of the modified sputtered\nfilms was monitored by atomic force microscopy (AFM), high resolution scanning\nelectron microscopy (HRSEM) and Rutherford backscattering spectrometry (RBS).\nThe most interesting observation was the formation of mound-like structures on\nthe metal surface. Morphological data were quantitatively analysed within the\nframework of the dynamic scaling theory. Analyses of the height-height\ncorrelation function for different doses yield roughness exponents $\\alpha $ in\nthe range 0.65 - 0.87, while the root-mean-square roughness amplitude $w$\nevolves with the dose $\\phi $ as a power law $w\\propto \\phi ^{\\beta}$, with the\ngrowth exponent, $\\beta $ $\\approx $ 0.3. The results are discussed.",
        "positive": "A phenomenological model for the spontaneous exchange bias effect: In this work we propose an alternative model to explain the spontaneous\nexchange bias (SEB) effect observed in spin glass (SG)-like systems. As in a\npreviously proposed model (Ref. 1), it is based on the unconventional dynamics\nof the SG-like moments at the magnetic hysteresis cycle. However, using a\nreliable estimate of the amount of SG-spins that are relaxing during the cycle,\nthe new model can correctly describe the changes in the SEB observed for\nmeasurements performed at different temperatures and different maximum applied\nfields."
    },
    {
        "anchor": "Control of magnetoelastic coupling in Ni/Fe multilayers using He$^+$ ion\n  irradiation: This study reports the effects of post-growth He$^+$ irradiation on the\nmagneto-elastic properties of a $Ni$ /$Fe$ multi-layered stack. The progressive\nintermixing caused by He$^+$ irradiation at the interfaces of the multilayer\nallows us to tune the saturation magnetostriction value with increasing He$^+$\nfluences, and even to induce a reversal of the sign of the magnetostrictive\neffect. Additionally, the critical fluence at which the absolute value of the\nmagnetostriction is dramatically reduced is identified. Therefore insensitivity\nto strain of the magnetic stack is nearly reached, as required for many\napplications. All the above mentioned effects are attributed to the combination\nof the negative saturation magnetostriction of sputtered Ni, Fe layers and the\npositive magnetostriction of the Ni$_{x}$Fe$_{1-x}$ alloy at the intermixed\ninterfaces, whose contribution is gradually increased with irradiation.\nImportantly the irradiation does not alter the layers polycrystalline\nstructure, confirming that post-growth He$^+$ ion irradiation is an excellent\ntool to tune the magneto-elastic properties of magnetic samples. A new class of\nspintronic devices can be envisioned with a material treatment able to\narbitrarily change the magnetostriction with ion-induced \"magnetic patterning\".",
        "positive": "Interface Engineering to Create a Strong Spin Filter Contact to Silicon: Integrating epitaxial and ferromagnetic Europium Oxide (EuO) directly on\nsilicon is a perfect route to enrich silicon nanotechnology with spin filter\nfunctionality.\n  To date, the inherent chemical reactivity between EuO and Si has prevented a\nheteroepitaxial integration without significant contaminations of the interface\nwith Eu silicides and Si oxides.\n  We present a solution to this long-standing problem by applying two\ncomplementary passivation techniques for the reactive EuO/Si interface:\n  ($i$) an $in\\:situ$ hydrogen-Si $(001)$ passivation and ($ii$) the\napplication of oxygen-protective Eu monolayers --- without using any additional\nbuffer layers.\n  By careful chemical depth profiling of the oxide-semiconductor interface via\nhard x-ray photoemission spectroscopy, we show how to systematically minimize\nboth Eu silicide and Si oxide formation to the sub-monolayer regime --- and how\nto ultimately interface-engineer chemically clean, heteroepitaxial and\nferromagnetic EuO/Si $(001)$ in order to create a strong spin filter contact to\nsilicon."
    },
    {
        "anchor": "Electrically controlled heat transport in multilayer graphene: The ability to control heat transport with electrical signals has been an\noutstanding challenge due to the lack of efficient electrothermal materials.\nPrevious attempts have mainly concentrated on phase-change and layered\nmaterials and encountered various problems such as low thermal conductivities\nand modest on/off ratios. Here, we demonstrate a graphene-based electrothermal\nswitch enabling electrically tuneable heat flow. The device uses reversible\nelectro-intercalation of ions to modulate the in-plane thermal conductivity of\ngraphene film by over thirteen-fold via electrically tuneable phonon\nscattering. We anticipate that our results could provide a realistic pathway\nfor adaptive thermal transport enabling a new class of electrically driven\nthermal devices which would find a broad spectrum of applications in aerospace\nand microelectronics.",
        "positive": "Mesoscopic structure of mixed type domain walls in multiaxial\n  ferroelectrics: The structure of 180-degree uncharged rotational domain wall in a multiaxial\nferroelectric film is studied within the framework of analytical\nLandau-Ginzburg-Devonshire (LGD) approach. The Finite Element Modelling (FEM)\nis used to solve numerically the system of the coupled nonlinear Euler-Lagrange\n(EL) differential equations of the second order for two components of\npolarization. We show that the structure of the domain wall and corresponding\n(meta)stable phase of the film are controlled by a single master parameter,\ndimensionless ferroelectric anisotropy {\\mu}. We fitted the static profile of a\nsolitary domain wall, calculated by FEM, with hyperbolic functions for\npolarization components, and extracted the five {\\mu}-dependent parameters from\nthe fitting to FEM curves. The high accuracy of the fitting results allows us\nto conclude that the analytical functions can be treated as the high-accuracy\nvariational solution of the static EL equations with cubic nonlinearity. We\nfurther derive the two-component analytical solutions of the static EL\nequations for a polydomain 180-degree domain structure in a multiaxial\nferroelectric film. The analysis of the free energy dependence on the film\nthickness and boundary conditions at its surfaces allows to select the domain\nstates corresponding to the minimal energy. The single-domain state is ground\nfor zero polarization derivative at the surfaces, while the poly-domain states\nminimize the system energy for zero polarization at the surfaces.\nCounterintuitively, the energy of the polydomain states split into two levels 0\nand 1 for zero polarization at the surfaces, and each of the levels is the\ninfinite set of the close-energy sub-levels, which morphology is characterized\nby different structure of the two-component polarization nodes."
    },
    {
        "anchor": "Detailed Electronic Structure of the Three-Dimensional Fermi Surface and\n  its Sensitivity to Charge Density Wave Transition in ZrTe3 Revealed by High\n  Resolution Laser-Based Angle-Resolved Photoemission Spectroscopy: The detailed information of the electronic structure is the key for\nunderstanding the nature of charge density wave (CDW) order and its\nrelationship with superconducting order in microscopic level. In this paper, we\npresent high resolution laser-based angle-resolved photoemission spectroscopy\n(ARPES) study on the three-dimensional (3D) hole-like Fermi surface around the\nBrillouin zone center in a prototypical qusi-one-dimensional CDW and\nsuperconducting system ZrTe3. Double Fermi surface sheets are clearly resolved\nfor the 3D hole-like Fermi surface around the zone center. The 3D Fermi surface\nshows a pronounced shrinking with increasing temperature. In particular, the\nquasiparticle scattering rate along the 3D Fermi surface experiences an anomaly\nnear the charge density wave transition temperature of ZrTe3 (~63 K). Signature\nof electron-phonon coupling is observed with a dispersion kink at ~20 meV; the\nstrength of the electron-phonon coupling around the 3D Fermi surface is rather\nweak. These results indicate that the 3D Fermi surface is also closely\nconnected to the charge-density-wave transition and suggest a more global\nimpact on the entire electronic structure induced by CDW phase transition in\nZrTe3.",
        "positive": "Magnetic and Electronic Switch in Metal Intercalated Two-Dimensional\n  GeP$_3$: Intercalation of foreign atoms in two dimensional hosts has been considered a\nquite promising route in order to engineer the electronic, and magnetic\nproperties in 2D plataforms. In the present study, we performed a\nfirst-principles theoretical investigation of the energetic stability, and the\nmagnetic/electronic properties of 2D GeP$_3$ doped by Cr atoms. Our total\nenergy results reveal the formation of thermodynamically stable Cr doped\nGeP$_3$ bilayer [(GeP$_3$)$_{BL}$], characterized by interstitial Cr atoms\nlying in the van der Waals (vdW) gap between (GeP$_3$)$_{BL}$\n[(GeP$_3$)$_{BL}^{Cr}$]. We show that the ground state row-wise\nantiferromagnetic (RW-AFM) phase of (GeP$_3$)$_{BL}^{Cr}$ can be tuned to a\nferromagnetic (FM) configuration upon compressive mechanical strain\n($\\varepsilon$), Cr$^{\\uparrow \\downarrow}\n\\xrightarrow{\\varepsilon}$Cr$^{\\uparrow \\uparrow}$. By considering its stacked\ncounterparts, (GeP$_3$)$_{BL}^{Cr}$/(GeP$_3$)$_{BL}^{Cr}$, and\n(GeP$_3$)$_{BL}^{Cr}$/Cr/(GeP$_3$)$_{BL}^{Cr}$, we found that such a magnetic\ntuning is dictated by a combination of intralayer and interlayer couplings,\nwhere the RW-AFM phase change to layer-by-layer FM (Cr$^{\\uparrow\n\\uparrow}$//Cr$^{\\uparrow \\uparrow}$) and AFM (Cr$^{\\uparrow\n\\uparrow}$/Cr$^{\\downarrow \\downarrow}$/Cr$^{\\uparrow \\uparrow}$) phases,\nrespectively. Further electronic band structure calculations show that these Cr\ndoped systems are metallic, characterized by the emergence of strain induced\nspin polarized channels at the Fermi level. These findings reveal that the\natomic intercalation, indeed, offers a new set of degree of freedom for the\ndesign and control the magnetic/electronic properties in 2D systems."
    },
    {
        "anchor": "Giant magnetoimpedance in Vitrovac amorphous ribbons over [0.3-400 MHz]\n  frequency range: Giant magneto impedance (GMI) effect for as-cast\nVitrovac$^{\\textrm{\\scriptsize\\textregistered}}$ amorphous ribbons\n(Vacuumschmelze, Germany) in two configurations (parallel and normal to the\nribbon axis) is studied over the frequency range [0.3-400 MHz] and under static\nmagnetic fields -160 Oe $< H_{dc} < $+160 Oe. A variety of peak features and\nGMI ratio values, falling within a small field range, are observed and\ndiscussed.",
        "positive": "Internal electric field originated from mismatch effect and its\n  influence on ferroelectric thin film properties: The ferroelectric thin film properties were calculated in phenomenological\ntheory framework. Surface energy that defined boundary conditions for\nEuler-Lagrange differential equation was written as surface tension energy. The\nlatter was expressed via surface polarization and tension tensor related to\nmismatch of a substrate and a film lattice constants and thermal expansion\ncoefficients. The calculations of the film polarization distribution,\ntemperature, thickness and external electric field dependence and hysteresis\nloops as well as average dielectric susceptibility dependence on temperature\nand film thickness have been performed allowing for mismatch-induced\npolarization Pm, leading to appearance of internal thickness dependent field.\nIt has been shown that this field influences drastically all the properties\nbehaviour. In particular the polarization profile becomes asymmetrical, average\npolarization temperature dependence resembles the one in the external electric\nfield, and there is possibility of external field screening by the internal\none. The obtained asymmetry of hysteresis loop makes it possible to suppose\nthat the self-polarization phenomenon recently observed in some films is\nrelated to mismatch effect. The thickness induced ferroelectric-paraelectric\nphase transition has been shown to exist when the Pm value is smaller than the\npolarization PS in the bulk. The large enough mismatch effect could be the\nphysical reason of ferroelectric phase conservation in ultrathin film. The\npossibility to observe the peculiarities of the films properties temperature\nand thickness dependencies related to mismatch effect is discussed."
    },
    {
        "anchor": "Insights into ultrafast demagnetization in pseudo-gap half metals: Interest in femtosecond demagnetization experiments was sparked by Bigot's\ndiscovery in 1995. These experiments unveil the elementary mechanisms coupling\nthe electrons' temperature to their spin order. Even though first quantitative\nmodels describing ultrafast demagnetization have just been published within the\npast year, new calculations also suggest alternative mechanisms.\nSimultaneously, the application of fast demagnetization experiments has been\ndemonstrated to provide key insight into technologically important systems such\nas high spin polarization metals, and consequently there is broad interest in\nfurther understanding the physics of these phenomena. To gain new and relevant\ninsights, we perform ultrafast optical pump-probe experiments to characterize\nthe demagnetization processes of highly spin-polarized magnetic thin films on a\nfemtosecond time scale. Previous studies have suggested shifting the Fermi\nenergy into the center of the gap by tuning the number of electrons and thereby\nto study its influence on spin-flip processes. Here we show that choosing\nisoelectronic Heusler compounds (Co2MnSi, Co2MnGe and Co2FeAl) allows us to\nvary the degree of spin polarization between 60% and 86%. We explain this\nbehavior by considering the robustness of the gap against structural disorder.\nMoreover, we observe that Co-Fe-based pseudo gap materials, such as partially\nordered Co-Fe-Ge alloys and also the well-known Co-Fe-B alloys, can reach\nsimilar values of the spin polarization. By using the unique features of these\nmetals we vary the number of possible spin-flip channels, which allows us to\npinpoint and control the half metals electronic structure and its influence\nonto the elementary mechanisms of ultrafast demagnetization.",
        "positive": "Pre-melting hcp to bcc Transition in Beryllium: Beryllium (Be) is an important material with wide applications ranging from\naerospace components to X-ray equipments. Yet a precise understanding of its\nphase diagram remains elusive. We have investigated the phase stability of Be\nusing a recently developed hybrid free energy computation method that accounts\nfor anharmonic effects by invoking phonon quasiparticles. We find that the hcp\nto bcc transition occurs near the melting curve at 0<P<11 GPa with a positive\nClapeyron slope of 41 K/GPa. The bcc phase exists in a narrow temperature range\nthat shrinks with increasing pressure, explaining the difficulty in observing\nthis phase experimentally. This work also demonstrates the validity of this\ntheoretical framework based on phonon quasiparticle to study structural\nstability and phase transitions in strongly anharmonic materials."
    },
    {
        "anchor": "Nonequilibrium plastic roughening of metallic glasses yields self-affine\n  topographies with strain-rate and temperature-dependent scaling exponents: We study nonequilibrium roughening during compressive plastic flow of\ninitially flat Cu$_{50}$Zr$_{50}$ metallic glass using large-scale molecular\ndynamics simulations. Roughness emerges at atomically flat interfaces beyond\nthe yield point of the glass. A self-affine rough topography is imprinted at\nyield and is reinforced during subsequent deformation. The imprinted\ntopographies have Hurst exponents that decrease with increasing strain-rate and\ntemperature. After yield, the root-mean-square roughness amplitude grows as the\nsquare-root of the applied strain with a prefactor that also drops with\nincreasing strain-rate and temperature. Our calculations reveal the emergence\nof spatial power-law correlations from homogeneous samples during plastic flow\nwith exponents that depend on the rate of deformation and the temperature. The\nresults have implications for interpreting and engineering roughness profiles.",
        "positive": "Silicon carbide stacking-order-induced doping variation in epitaxial\n  graphene: Generally, it is supposed that the Fermi level in epitaxial graphene is\ncontrolled by two effects: p-type polarization doping induced by the bulk of\nthe hexagonal SiC(0001) substrate and overcompensation by donor-like states\nrelated to the buffer layer. In this work, we evidence that this effect is also\nrelated to the specific underlying SiC terrace. We fabricated a periodic\nsequence of non-identical SiC terraces, which are unambiguously attributed to\nspecific SiC surface terminations. A clear correlation between the SiC\ntermination and the electronic graphene properties is experimentally observed\nand confirmed by various complementary surface-sensitive methods. We attribute\nthis correlation to a proximity effect of the SiC termination-dependent\npolarization doping on the overlying graphene layer. Our findings open a new\napproach for a nano-scale doping-engineering by self-patterning of epitaxial\ngraphene and other 2D layers on dielectric polar substrates."
    },
    {
        "anchor": "Stimulated Rayleigh Scattering Enhanced by a Longitudinal Plasma Mode in\n  a Periodically Driven Dirac Semimetal Cd$_3$As$_2$: Using broadband (12-45 THz) multi-terahertz spectroscopy, we show that\nstimulated Rayleigh scattering dominates the transient optical conductivity of\ncadmium arsenide, a Dirac semimetal, under an optical driving field at 30 THz.\nThe characteristic dispersive lineshape with net optical gain is accounted for\nby optical transitions between light-induced Floquet subbands, strikingly\nenhanced by the longitudinal plasma mode. Stimulated Rayleigh scattering with\nan unprecedentedly large refractive index change may pave the way for slow\nlight generation in conductive solids at room temperature.",
        "positive": "Dielectric tensor of monoclinic Ga$_2$O$_3$ single crystals in the\n  spectral range $0.5 - 8.5\\,$eV: The dielectric tensor of $\\beta$-Ga$_2$O$_3$ was determined by generalized\nspectroscopic ellipsometry in a wide spectral range from $0.5\\,\\mathrm{eV}$ to\n$8.5\\,\\mathrm{eV}$ as well as by calculation including quasiparticle bands and\nexcitonic effects. The dielectric tensors obtained by both methods are in\nexcellent agreement with each other and the observed transitions in the\ndielectric function are assigned to the corresponding valence bands. It is\nshown that the off-diagonal element of the dielectric tensor reaches values up\nto $|\\varepsilon_{xz} | \\approx 0.30 $ and cannot be neglected. Even in the\ntransparent spectral range where it is quite small ($|\\varepsilon_{xz} | < 0.02\n$) it causes a rotation of the dielectric axes around the symmetry axis of up\nto $20^\\circ$."
    },
    {
        "anchor": "Carbon-contaminated topological defects in hBN: a potential new class of\n  single photon emitters: Topological defects, such as Stone-Wales defects and grain boundaries, are\ncommon in 2D materials. In this exploratory study, we investigate the intricate\ninterplay of carbon contamination and topological defects revealing a new class\nof color centers in hexagonal boron nitride. We demonstrate that carbon\ncontamination and strain can both stabilize Stone-Wales configurations with\ndesirable optical properties. Inspired by these results, we further demonstrate\nthat carbon atoms at grain boundaries can resolve energetic B-B and N-N bonds\nand give rise to highly favorable atomic structures potentially leading to the\naccumulation of carbon contamination at grain boundaries. We identify\ncarbon-contaminated topological defects that give rise to color centers\nemitting in the visible spectral range with short radiative lifetime and high\nDebye-Waller factors. Our discoveries shed light on a new class of defects and\npave the way towards the identification of color centers and single photon\nemitters in hBN.",
        "positive": "A Multiscale Investigation of the Physical Origins of\n  Tension--Compression Asymmetry in Crystals and their Implications for Cyclic\n  Behavior: Most of crystalline materials develop an hysteresis on their deformation\ncurve when a mechanical loading is applied in alternating directions. This\neffect, also known as the Bauschinger effect, is intimately related to the\nreversibile part of the plastic deformation and controls the materials damage\nand ultimately their failure. In the present work, we associate mesoscale\nDislocation Dynamics simulations and Finite Element simulations to identify two\noriginal dislocation mechanisms at the origin of the traction/compression\nasymmetry and quantify their impacts on the cyclic behaviour of FCC\nsingle-crystals. After demonstrating that no long-range internal stresses can\nbe measured in the simulations, careful analysis of the dislocation network\nshow that the Bauschinger effect is caused by an asymmetry in the stability of\njunctions formed from segments whose curvature is determined by the applied\nstress, and a significant portion of the stored dislocation segments is easily\nrecovered during the backward motion of dislocations in previously explored\nregions of the crystal. These mechanisms are incorporated into a modified\ncrystal plasticity framework with few parameters quantified from statistical\nanalysis of Dislocation Dynamics simulations or from the literature. This\nstrategy has a real predictive capability and the macroscale results are in\ngood agreement with most of the experimental literature existing on the\nBauschinger and cyclic deformation of FCC single-crystals. This work provides\nvaluable mechanistic insight to assist in the interpretation of experiments and\nthe design of structural components to consolidate their life under cyclic\nloading."
    },
    {
        "anchor": "Unsupervised learning of ferroic variants from atomically resolved STEM\n  images: An approach for the analysis of atomically resolved scanning transmission\nelectron microscopy data with multiple ferroic variants in the presence of\nimaging non-idealities and chemical variabilities based on a rotationally\ninvariant variational autoencoder (rVAE) is presented. We show that an optimal\nlocal descriptor for the analysis is a sub-image centered at specific atomic\nunits, since materials and microscope distortions preclude the use of an ideal\nlattice as a reference point. The applicability of unsupervised clustering and\ndimensionality reduction methods is explored and are shown to produce clusters\ndominated by chemical and microscope effects, with a large number of classes\nrequired to establish the presence of rotational variants. Comparatively, the\nrVAE allows extraction of the angle corresponding to the orientation of ferroic\nvariants explicitly, enabling straightforward identification of the ferroic\nvariants as regions with constant or smoothly changing latent variables and\nsharp orientational changes. This approach allows further exploration of the\nchemical variability by separating the rotational degrees of freedom via rVAE\nand searching for remaining variability in the system. The code used in the\nmanuscript is available at\nhttps://github.com/saimani5/ferroelectric_domains_rVAE.",
        "positive": "Imaging of Single La Vacancies in LaMnO$_{3}$: We report an approach for three-dimensional imaging of single vacancies using\nhigh precision quantitative high-angle annular dark-field Z-contrast scanning\ntransmission electron microscopy (STEM). Vacancies are identified by both the\nreduction in scattered intensity created by the missing atom and the distortion\nof the surrounding atom positions. Vacancy positions are determined laterally\nto a unique lattice site in the image and in depth to within one of two lattice\nsites by dynamical diffraction effects. 35 single La vacancies are identified\nin images of a LaMnO3 thin film sample. The vacancies are randomly distributed\nin depth and correspond to a La vacancy concentration of 0.79%, which is\nconsistent with the level of control of cation stoichiometry within our\nsynthesis process (~1%) and with the equilibrium concentration of La vacancies\nunder the film growth conditions. This work demonstrates an approach to\ncharacterizing low concentrations of vacancies with high spatial resolution."
    },
    {
        "anchor": "Long-Range Order in Electronic Transport through Disordered Metal Films: Ultracold atom magnetic field microscopy enables the probing of current flow\npatterns in planar structures with unprecedented sensitivity. In\npolycrystalline metal (gold) films we observe long-range correlations forming\norganized patterns oriented at +/- 45 deg relative to the mean current flow,\neven at room temperature and at length scales orders of magnitude larger than\nthe diffusion length or the grain size. The preference to form patterns at\nthese angles is a direct consequence of universal scattering properties at\ndefects. The observed amplitude of the current direction fluctuations scales\ninversely to that expected from the relative thickness variations, the grain\nsize and the defect concentration, all determined independently by standard\nmethods. This indicates that ultracold atom magnetometry enables new insight\ninto the interplay between disorder and transport.",
        "positive": "Drift-Induced Step Instabilities Due to the Gap in the Diffusion\n  Coefficient: On a Si(111) vicinal face near the structural transition temperature, the $1\n\\times 1$ structure and the $7 \\times 7$ structure coexist in a terrace: the $1\n\\times 1$ structure is in the lower side of the step edge and the $7 \\times 7$\nstructure in the upper side. The diffusion coefficient of adatoms is different\nin the two structures. Taking account of the gap in the diffusion coefficient\nat the step, we study the possibility of step wandering induced by drift of\nadatoms. A linear stability analysis shows that the step wandering always\noccurs with step-down drift if the diffusion coefficient has a gap at the step.\nFormation of straight grooves by the step wandering is expected from a\nnonlinear analysis. The stability analysis also shows that step bunching occurs\nirrespective of the drift direction if the diffusion in the lower side of the\nstep is faster. The step bunching disturbs the formation of grooves. If\nstep-step repulsion is strong, however, the step bunching is suppressed and the\nstraight grooves appear. Monte Carlo simulation confirms these predictions."
    },
    {
        "anchor": "Homologous self-assembled superlattices: What causes their periodic\n  polarity switching? Review, model, and experimental test: Quantum semiconductor structures are commonly achieved by bandgap engineering\nthat relies on the ability to switch from one semiconductor to another during\ntheir growth. Growth of a superlattice is typically demanding technologically.\nIn contrast, accumulated evidence points to a tendency among a certain class of\nmultiple-cation binary oxides to self-assemble spontaneously as superlattice\nstructures. This class has been dubbed the homologous superlattices. For a\nfamous example, when a mixture of indium and zinc is oxidized, the phases of\nIn-O and ZnO separate in an orderly periodic manner, along the ZnO polar axis,\nwith polarity inversion taking place between consecutive ZnO sections. As we\nreview here, the same structure has been observed when the indium was replaced\nwith other metals, and perhaps even in ZnO alone. This peculiar self-assembled\nstructure has been attracting research over the past decade. The purpose of\nthis study is to gain understanding of the physics underlying the formation of\nthis unique structure. Here, we first provide an extensive review of the\naccumulated literature on these spontaneously-formed structures and then\npropose an explanation for the long-standing mystery of this intriguing\nself-assembly in the form of an electrostatic growth phenomenon and test the\nproposed model on experimental data.",
        "positive": "Large lattice distortions associated with the magnetic transition in\n  La0.7Sr0.3MnO3: Colossal magnetoresistance (CMR) is associated with the phase transition from\na metallic ferromagnetic to insulating paramagnetic phase, which can be\ncontrolled by an applied magnetic field. The insulating phase occurs due to\ntrapping of the charge carriers by polaronic lattice distortions, which raise\nthe resistivity. Theories based on local physics predict that the magnitude of\nthe resistivity jump at Tc is determined by how much, on average, the amplitude\nof these distortions increases at the phase transition. Using neutron\nscattering, we measured the average distortion amplitude in La0.7Sr0.3MnO3.\nSurprisingly, its increase from below to above Tc is just as large as in other\nmanganites, which have a much larger resistivity jump. This result suggests\nthat the strength of CMR is determined not by the size of distortions, but by\ntheir cooperative nature specific to each compound. Existing theories need to\nbe extended to include correlations between different unit cells to explain and\npredict the strength of CMR."
    },
    {
        "anchor": "An asynchronous parallel high-throughput model calibration framework for\n  crystal plasticity finite element constitutive models: Crystal plasticity finite element model (CPFEM) is a powerful numerical\nsimulation in the integrated computational materials engineering (ICME)\ntoolboxes that relates microstructures to homogenized materials properties and\nestablishes the structure-property linkages in computational materials science.\nHowever, to establish the predictive capability, one needs to calibrate the\nunderlying constitutive model, verify the solution and validate the model\nprediction against experimental data. Bayesian optimization (BO) has stood out\nas a gradient-free efficient global optimization algorithm that is capable of\ncalibrating constitutive models for CPFEM. In this paper, we apply a recently\ndeveloped asynchronous parallel constrained BO algorithm to calibrate\nphenomenological constitutive models for stainless steel 304L, Tantalum, and\nCantor high-entropy alloy.",
        "positive": "Unraveling many-body effects in ZnO: Combined study using\n  momentum-resolved electron energy-loss spectroscopy and first-principles\n  calculations: We present a detailed study of the dielectric response of ZnO using a\ncombination of low-loss momentum-resolved electron energy-loss spectroscopy\n(EELS) and first-principles calculations at several levels of theory, from the\nindependent particle and the random phase approximation with different variants\nof density functional theory (DFT), including hybrid and DFT$+U$ schemes; to\nthe Bethe-Salpeter equation (BSE). We use a method based on the $f$-sum rule to\nobtain the momentum-resolved experimental loss function and absorption spectra\nfrom EELS measurements. We characterize the main features in the direct and\ninverse dielectric functions of ZnO and their dispersion, associating them to\nsingle-particle features in the electronic band structure, while highlighting\nthe important role of many-body effects such as plasmons and excitons. We\ndiscuss different signatures of the high anisotropy in the response function of\nZnO, including the symmetry of the excitonic wave-functions."
    },
    {
        "anchor": "Electronic transport and thermoelectricity in selenospinel\n  Cu$_{6-x}$Fe$_{4+x}$Sn$_{12}$Se$_{32}$: We report a study of selenospinel Cu$_{6-x}$Fe$_{4+x}$Sn$_{12}$Se$_{32}$ ($x$\n= 0, 1, 2) single crystals, which crystalize in a cubic structure with the\n$Fd\\overline{3}m$ space group, and show typical semiconducting behavior. The\nlarge discrepancy between the activation energy for electrical conductivity\n$E_\\rho$ (32.3 $\\sim$ 69.8 meV), and for thermopower $E_\\textrm{S}$ (3.2 $\\sim$\n11.5 meV), indicates a polaronic transport mechanism between 350 and 50 K. With\ndecreasing temperature, it evolves into variable-range hopping conduction.\nFurthermore, the heat capacity shows a hump around 25(5) K and diverges from\nthe Debye $T^3$ law at low temperatures, indicating the observation of\nstructural glassy features in these crystalline solids.",
        "positive": "Density-functional-theory calculations of molecular nitrogen on\n  ruthenium cluster: Density-functional-theory calculations for the adsorption of molecular\nnitrogen on ruthenium surface are reported. It is found that nitrogen molecule\nis adsorbed while standing perpendicular to the triangular surface of\nruthenium. The doping by K atoms favours the adsorption of molecular nitrogen.\nThe calculation of the adsorption energy has also been performed on iron and\nosmium clusters which shows that ruthenium adsorbs better than iron or osmium.\nIt is found that potential for atomic nitrogen is deeper and more stable than\nthat of molecular nitrogen and hence atomic nitrogen is important for\ncatalysis."
    },
    {
        "anchor": "Peculiarities of Laue Diffraction of Neutrons in Strongly Absorbing\n  Crystals: Well-known Kato's theory of the Laue diffraction of spherical x-ray waves is\ngeneralized to the case of the neutron diffraction in strongly absorbing\ncrystals, taking into consideration both the potential and the resonant\nscattering of neutrons by nuclei as well as a realistic angular dispersion of\nincident neutrons. The saddle-point method is applied for estimation of the\nangular integrals, being more adequate in the case of strongly absorbing\ncrystals than the usually used stationary-phase approximation. It is found that\nthe intensity distribution of the diffracted and refracted beams along the\nbasis of the Borrmann triangle significantly depends on the deviation of the\nneutron energy from the nuclear resonant level. When comparing our calculations\nwith the Shull's experimental data on neutron diffraction in silicon we regard\nalso the role of finite width of the collimating and scanning slits.",
        "positive": "Machine Learning Forcefield for Silicate Glasses: Developing accurate, transferable, and computationally-efficient interatomic\nforcefields is key to facilitate the modeling of silicate glasses. However, the\nhigh number of forcefield parameters that need to be optimized render\ntraditional parameterization methods poorly efficient or potentially subject to\nbias. Here, we present a new forcefield parameterization methodology based on\nab initio molecular dynamics simulations, Gaussian process regression, and\nBayesian optimization. By taking the example of glassy silica, we show that our\nmethodology yields a new interatomic forcefield that offers an unprecedented\ndescription of the atomic structure of silica. This methodology offers a new\nroute to efficiently parameterize new empirical interatomic forcefields for\nsilicate glasses with very limited need for intuition."
    },
    {
        "anchor": "Cooling Rate Effects on the Structure of 45S5 Bioglass: Computational\n  and Experimental Evidence of Si--P Avoidance: Due to its ability to bond with living tissues upon dissolution, 45S5\nbioglass and related compositions are promising materials for the replacement,\nregeneration, and repair of hard tissues in the human body. However, the\ndetails of their atomic structure remain unclear. This is partially due to the\nnon-equilibrium nature of glasses, as their non-crystalline structure is highly\ndependent on their thermal history, namely, the cooling rate used during\nquenching. Herein, using molecular dynamics (MD) simulations and magic angle\nspinning nuclear magnetic resonance (MAS-NMR) spectroscopy experiments, we\ninvestigate the structure of the nominal 45S5 bioglass composition prepared\nusing cooling rates ranging over several orders of magnitude. We show that the\nsimulations results are in very good agreement with experimental data, provided\nthat they are extrapolated toward lower cooling rates achieved in experiments.\nThese results highlight that previously reported inconsistencies between\nsimulations and experiments stem from the difference in cooling rate, thereby\naddressing one of the longstanding questions on the structure of bioglass.\nBased on these results, we demonstrate the existence of a Si--P avoidance\nbehavior, which may be key in controlling the bioactivity of 45S5 bioglass.",
        "positive": "A new analytical model for the contact of Gaussian rough surfaces: This paper advances an analytical incremental contact model for the purely\nelastic or elastic-perfectly plastic Gaussian rough surfaces. The contact is\nmodelled by the accumulation of identical circular contacts with radius given\nby the total truncated area at varying heights divided by the contact patch\nnumber. The contact area-load relationship is derived analytically, showing\napproximate linearity for the contact fraction up to 10%. Good agreement is\nfound between the new proposed model and the direct finite element simulations.\nTo characterize the influence of plastic deformation, a dimensionless\nplasticity parameter is introduced as the ratio of yield strain to root mean\nsquare gradient of the rough surface. It is demonstrated that the general\nelastic-plastic contact response would approach to the limit of purely elastic\nas the plasticity parameter increases."
    },
    {
        "anchor": "Comparison of dynamic mechanical properties of non-superheated and\n  superheated A357 alloys: The influence of superheat treatment on the microstructure and dynamic\nmechanical properties of A357 alloys has been investigated. The study of\nmicrostructure was performed by the optical microscope. Dynamic mechanical\nproperties (storage modulus, loss modulus, and damping capacity) were measured\nby the dynamic mechanical analyzer (DMA). Microstructure showed coarser and\nangular eutectic Si particles with larger {\\alpha}-Al dendrites in the\nnon-superheated A357 alloy. In contrast, finer and rounded eutectic Si\nparticles together with smaller and preferred oriented {\\alpha}-Al dendrites\nhave been observed in the superheated A357 alloy. Dynamic mechanical properties\nshowed an increasing trend of loss modulus and damping capacity meanwhile a\ndecreasing trend of storage modulus at elevated temperatures for superheated\nand non-superheated A357 alloys. The high damping capacity of superheated A357\nhas been ascribed to the grain boundary damping at elevated temperatures.",
        "positive": "An Ising Model for Metal-Organic Frameworks: We present a three-dimensional Ising model where lines of equal spins are\nfrozen in such that they form an ordered framework structure. The frame spins\nimpose an external field on the rest of the spins (active spins). We\ndemonstrate that this \"porous Ising model\" can be seen as a minimal model for\ncondensation transitions of gas molecules in metal-organic frameworks. Using\nMonte Carlo simulation techniques, we compare the phase behavior of a porous\nIsing model with that of a particle-based model for the condensation of methane\n(CH$_4$) in the isoreticular metal-organic framework IRMOF-16. For both models,\nwe find a line of first-order phase transitions that end in a critical point.\nWe show that the critical behavior in both cases belongs to the 3D Ising\nuniversality class, in contrast to other phase transitions in confinement such\nas capillary condensation."
    },
    {
        "anchor": "First order magneto-structural transition and magnetocaloric effect in\n  MnNiGe$_{0.9}$Ga$_{0.1}$: The first order magneto-structural transition ($T_t\\simeq95$ K) and\nmagnetocaloric effect in MnNiGe$_{0.9}$Ga$_{0.1}$ are studied via powder x-ray\ndiffraction and magnetization measurements. Temperature dependent x-ray\ndiffraction measurements reveal that the magneto-structural transition remains\nincomplete down to 23 K, resulting in a coexistence of antiferromagnetic and\nferromagnetic phases at low temperatures. The fraction of the high temperature\nNi$_2$In-type hexagonal ferromagnetic and low temperature TiNiSi-type\northorhombic antiferromagnetic phases is estimated to be $\\sim 40\\%$ and $\\sim\n60\\%$, respectively at 23 K. The ferromagnetic phase fraction increases with\nincreasing field which is found to be in non-equilibrium state and gives rise\nto a weak re-entrant transition while warming under field-cooled condition. It\nshows a large inverse magnetocaloric effect across the magneto-structural\ntransition and a conventional magnetocaloric effect across the second order\nparamagnetic to ferromagnetic transition. The relative cooling power which\ncharacterizes the performance of a magnetic refrigerant material is found to be\nreasonably high compared to the other reported magnetocaloric alloys.",
        "positive": "Rotational hysteresis of the exchange anisotropy direction in Co/FeMn\n  thin films: We have investigated the effects of rotating an applied field on the exchange\nanisotropy in Co/FeMn thin films. When the applied field is initially along the\ncooling field direction, the longitudinal hysteresis loop has a maximum\ncoercivity and the transverse hysteresis loop is flat, indicating that the\nexchange field is along the cooling field direction. When the applied field\nangle is rotated away and then restored to the original field cooling\ndirection, the exchange anisotropy direction has changed. The rotation of the\nexchange field direction trails the applied field and is hysteretic. The\nrotational hysteresis of the exchange field direction is due to the weak\nanisotropy in thin FeMn layers, and decreases with increasing FeMn thickness."
    },
    {
        "anchor": "Exchange constant and domain wall width in (Ga,Mn)(As,P) films with\n  self-organization of magnetic domains: The incorporation of Phosphorus into (Ga,Mn)As epilayers allows for the\ntuning of the magnetic easy axis from in-plane to perpendicular-to-plane\nwithout the need for a (Ga,In)As template. For perpendicular easy axis, using\nmagneto-optical imaging a self-organized pattern of up- and down-magnetized\ndomains is observed for the first time in a diluted magnetic semiconductor.\nCombining Kerr microscopy, magnetometry and ferromagnetic resonance\nspectroscopy, the exchange constant and the domain wall width parameter are\nobtained as a function of temperature. The former quantifies the effective\nMn-Mn ferromagnetic interaction. The latter is a key parameter for domain wall\ndynamics. The comparison with results obtained for (Ga,Mn)As/(Ga,In)As reveals\nthe improved quality of the (Ga,Mn)As$_{1-y}$P$_y$ layers regarding domain wall\npinning, an increase of the domain wall width parameter and of the effective\nMn-Mn spin coupling. However, at constant Mn doping, no significant increase of\nthis coupling is found with increasing P concentration in the investigated\nrange.",
        "positive": "Tailor-made Quantum Well-in-a-Well Systems: Their Bound States and\n  Scattering Properties: The resulting stationary states and scattering properties of an effective\npotential brought about by embedding a quantum well in another well are\ninvestigated in this work. The composite well system is constructed via a\nsuperposition of modified Poeschl - Teller potential wells. The energy spectrum\nin each composite well is obtained using the shooting method and the transport\nof a particle above this system is analyzed using the transfer matrix method.\nIt is shown that decreasing the size of the embedded middle well lowers the\nground state energy of the well-in-a-well system. Moreover, the bound states\nincrease in number and become more evenly spaced. In addition, the transmission\nprobability of a free particle incident above a composite well is lowest for\nthe system with a large embedded well as compared to well-in-a-well systems of\nthe same depth. Small variations in designed potential wells yield different\nquantum mechanical features."
    },
    {
        "anchor": "The Mechanism of the Ultra-Fast Crystal Growth of Pure Metals from their\n  Melts: A crystal of pure nickel grows from its melt at a rate that reaches 70 meters\nper second. This extraordinary growth rate has led to the suggestion that\nmetallic crystals might provide the next generation of phase change materials.\nThe huge crystal growth rates of metals are a consequence of kinetics without\nactivated control, in sharp contrast to the prediction of the classic theory of\ncrystal growth. While the existence of growth kinetics without barriers is now\nwell established in atomic melts, no physical explanation for the absence of an\nactivation barrier to ordering has been established. It is something of a\nparadox that diffusion in the liquid metal is governed by thermal activation\nwhile the movement of the same atoms as they organize into a crystal is not. In\nthis paper we use computer simulations of crystallization in pure metals to\nexplicitly resolve the origin of the growth kinetics without barriers.",
        "positive": "Modelling Surface Segregation in Compositionally Complex Alloys with\n  Ab-Initio Accuracy: Compositionally complex alloys or concentrated solid solutions are the latest\nfrontier in catalyst design, but mixing different elements in one catalyst may\nresult in surface segregation. Atomistic simulations can predict segregation\npatterns, but standard approaches based on mean-field models, cluster\nexpansion, or classical interatomic potentials are often limited for the\ndescription of multicomponent alloys. We present machine learning potentials\nthat can describe surface segregation with near DFT accuracy. The method is\nused to study a complex Co-Cu-Fe-Mo-Ni quinary alloy. For this alloy, an\nunexpected segregation of Co, which has a relatively high surface energy, is\nobserved. We rationalize this surprising mechanism in terms of simple\ntransition-metal chemistry."
    },
    {
        "anchor": "Deep machine learning potentials for multicomponent metallic melts:\n  development, predictability and compositional transferability: The use of machine learning interatomic potentials (MLIPs) in simulations of\nmaterials is a state-of-the-art approach, which allows achieving nearly\n\\textit{ab initio} accuracy with orders of magnitude less computational cost.\nMulticomponent disordered systems have a highly complicated potential energy\nsurface due to both topological and compositional disorder. That arises issues\nin MLIPs developing, such as optimal design strategy of potentials and their\npredictability and transferability. Here we address MLIPs for multicomponent\nmetallic melts taking the ternary Al-Cu-Ni ones as a convenient example. We use\nmany-body deep machine learning potentials as implemented in the DeePMD-kit to\nbuild MLIP that allows describing both atomic structure and dynamics of the\nsystem in the whole composition range. Doing that we consider different sets of\nneural networks hyperparameters and learning schemes to create an optimal MLIP,\nwhich allows archiving good accuracy in comparison with both \\textit{ab initio}\nand experimental data. We find that developed MLIP demonstrates good\ncompositional transferability, which extends far beyond compositional\nfluctuations in the training configurations. The results obtained open up\nprospects for simulating structural and dynamical properties of multicomponent\nmetallic alloys with MLIPs.",
        "positive": "Perspective: strain and strain gradient engineering in membranes of\n  quantum materials: Strain is powerful for discovery and manipulation of new phases of matter;\nhowever, the elastic strains accessible to epitaxial films and bulk crystals\nare typically limited to small ($<2\\%$), uniform, and often discrete values.\nThis Perspective highlights new directions for strain and strain gradient\nengineering in free-standing single crystalline membranes of quantum materials.\nMembranes enable large ($\\sim 10\\%$), continuously tunable strains and strain\ngradients via bending and rippling. Moreover, strain gradients break inversion\nsymmetry to activate polar distortions, ferroelectricity, chiral spin textures,\nnovel superconductivity, and topological states. Recent advances in membrane\nsynthesis by remote epitaxy and sacrificial etch layers enable extreme strains\nin new materials, including transition metal oxides and Heusler compounds,\ncompared to natively van der Waals (vdW) materials like graphene. We highlight\nnew opportunities and challenges for strain and strain gradient engineering in\nmembranes of non-vdW materials."
    },
    {
        "anchor": "Temperature-driven Phase Transformation in Y_3Co: Neutron Scattering and\n  First-principles Studies: Contrary to previous studies that identified the ground state crystal\nstructure of the entire R_3Co series (R is a rare earth) as orthorhombic Pnma,\nwe show that Y_3Co undergoes a structural phase transition at T_t=160K. Single\ncrystal neutron diffraction data reveal that at T_t the trigonal prisms formed\nby a cobalt atom and its six nearest-neighbor yttrium atoms experience\ndistortions accompanied by notable changes of the Y-Co distances. The formation\nof the low-temperature phase is accompanied by a pronounced lattice distortion\nand anomalies seen in heat capacity and resistivity measurements. Density\nfunctional theory calculations reveal a dynamical instability of the Pnma\nstructure of Y_3Co. In particular, a transversal acoustic phonon mode along the\n(00z) direction has imaginary frequencies at z<1/4. Employing inelastic neutron\nscattering measurements we find a strong damping of the (00z) phonon mode below\na critical temperature T_t. The observed structural transformation causes the\nreduction of dimensionality of electronic bands and decreases the electronic\ndensity of states at the Fermi level that identifies Y_3Co as a system with the\ncharge density wave instability.",
        "positive": "Millimeter-sized magnetic domains in perpendicularly magnetized\n  ferrimagnetic Mn4N thin films grown on SrTiO3: The use of epitaxial layers for domain wall-based spintronic applications is\noften hampered by the presence of pinning sites. Here, we show that when\ndepositing Mn4N(10 nm) epitaxial films, the replacement of MgO(001) by\nSrTiO3(001) substrates allows minimizing the misfit, and to obtain an improved\ncrystalline quality, a sharper switching, a full remanence, a high anisotropy\nand remarkable millimeter-sized magnetic domains, with straight and smooth\ndomain walls. In a context of rising interest for current-induced domain wall\nmotion in rare"
    },
    {
        "anchor": "Insights into lithium manganese oxide-water interfaces using machine\n  learning potentials: Unraveling the atomistic and the electronic structure of solid-liquid\ninterfaces is the key to the design of new materials for many important\napplications, from heterogeneous catalysis to battery technology. Density\nfunctional theory (DFT) calculations can in principle provide a reliable\ndescription of such interfaces, but the high computational costs severely\nrestrict the accessible time and length scales. Here, we report machine\nlearning-driven simulations of various interfaces between water and lithium\nmanganese oxide (Li$_x$Mn$_2$O$_4$), an important electrode material in lithium\nion batteries and a catalyst for the oxygen evolution reaction. We employ a\nhigh-dimensional neural network potential (HDNNP) to compute the energies and\nforces several orders of magnitude faster than DFT without loss in accuracy. In\naddition, a high-dimensional neural network for spin prediction (HDNNS) is\nutilized to analyze the electronic structure of the manganese ions. Combining\nthese methods, a series of interfaces is investigated by large-scale molecular\ndynamics. The simulations allow us to gain insights into a variety of\nproperties like the dissociation of water molecules, proton transfer processes,\nand hydrogen bonds, as well as the geometric and electronic structure of the\nsolid surfaces including the manganese oxidation state distribution,\nJahn-Teller distortions, and electron hopping.",
        "positive": "Infrared phonon anomaly and magnetic excitations in single-crystal\n  Cu$_{3}$Bi(SeO$_{3}$)$_{2}$O$_{2}$Cl: Infrared reflection and transmission as a function of temperature have been\nmeasured on single crystals of Cu$_{3}$Bi(SeO$_{3}$)$_{2}$O$_{2}$Cl. The\ncomplex dielectric function and optical properties along all three principal\naxes of the orthorhombic cell were obtained via Kramers-Kronig analysis and by\nfits to a Drude-Lorentz model. Below 115 K, 16 additional modes\n(8(E$\\parallel\\hat{a}$)+6(E$\\parallel\\hat{b}$)+2(E$\\parallel\\hat{c}$)) appear\nin the phonon spectra; however, powder x-ray diffraction measurements do not\ndetect a new structure at 85 K. Potential explanations for the new phonon modes\nare discussed. Transmission in the far infrared as a function of temperature\nhas revealed magnetic excitations originating below the magnetic ordering\ntemperature ($T_{c}\\sim$24 K). The origin of the excitations in the\nmagnetically ordered state will be discussed in terms of their response to\ndifferent polarizations of incident light, behavior in externally-applied\nmagnetic fields, and the anisotropic magnetic properties of\nCu$_{3}$Bi(SeO$_{3}$)$_{2}$O$_{2}$Cl as determined by d.c. susceptibility\nmeasurements."
    },
    {
        "anchor": "Probing the interactions between interstitial hydrogen atoms in niobium\n  through density functional theory calculations: Past experiments about hydrogen absorption in niobium have revealed specific\nproperties about interactions between interstitial hydrogen atoms. It has been\nreported that there are long-range attractive and short-range repulsive\ninteractions between interstitial hydrogen atoms in niobium. It has also been\nreported that these interactions are of many-body nature. While previous\nunderstanding of these interactions is based on experimental inferences from\npast experiments, through these calculations, for the first time, we can\nunderstand the nature of the interactions at a fundamental level. In this work,\nwe use Density Functional Theory calculations to study the interactions of\ninterstitial hydrogen atoms in niobium. We report here that these interactions\nare a combination of an attractive, indirect image interaction and a repulsive,\ndirect interaction. Through our calculations, we also infer here that these\ninteractions indeed have many-body characteristics.",
        "positive": "Microscopic origin of the structural phase transitions at the Cr2O3\n  (0001) surface: The surface of a Cr2O3 (0001) film epitaxially grown on Cr undergoes an\nunusual reentrant sequence of structural phase transitions. In order to\nunderstand the underlying microscopic mechanisms, the structural and magnetic\nproperties of the Cr2O3 (0001) surface are here studied using first-principles\nelectronic structure calculations. Two competing surface Cr sites are\nidentified. The energetics of the surface is described by a configurational\nHamiltonian with parameters determined using total energy calculations for\nseveral surface supercells. Effects of epitaxial strain and magnetic ordering\non configurational interaction are also included. The thermodynamics of the\nsystem is studied using Monte Carlo simulations. At zero strain the surface\nundergoes an ordering phase transition at 165 K. Tensile epitaxial strain\ntogether with antiferromagnetic ordering drive the system toward strong\nconfigurational frustration, suggesting the mechanism for the disordering phase\ntransition at lower temperatures."
    },
    {
        "anchor": "Robust luminescence of the silicon-vacancy center in diamond at high\n  temperatures: We performed high-temperature luminescence studies of silicon-vacancy color\ncenters obtained by ion implantation in single crystal diamond. We observed\nreduction of the integrated fluorescence upon increasing temperature,\nascribable to a transition channel with an activation energy of 180 meV that\npopulates a shelving state. Nonetheless, the signal decreased only 50% and 75%\nwith respect to room temperature at 500 K and 700 K, respectively. In addition,\nthe color center is found highly photostable at temperatures exceeding 800 K.\nThe luminescence of this color center is thus extremely robust even at large\ntemperatures and it holds promise for novel diamond-based light-emitting\ndevices.",
        "positive": "Ab initio quality neural-network potential for sodium: An interatomic potential for high-pressure high-temperature (HPHT)\ncrystalline and liquid phases of sodium is created using a neural-network (NN)\nrepresentation of the ab initio potential energy surface. It is demonstrated\nthat the NN potential provides an ab initio quality description of multiple\nproperties of liquid sodium and bcc, fcc, cI16 crystal phases in the P-T region\nup to 120 GPa and 1200 K. The unique combination of computational efficiency of\nthe NN potential and its ability to reproduce quantitatively experimental\nproperties of sodium in the wide P-T range enables molecular dynamics\nsimulations of physicochemical processes in HPHT sodium of unprecedented\nquality."
    },
    {
        "anchor": "Large Magnetic-Field-Induced Strain at the Spin-Reorientation Transition\n  in the A-Site Ordered Spinel Oxide LiFeCr4O8: Sintered samples of a spinel oxide LiFeCr4O8, where Cr3+ and Fe3+ ions have\nlocalized moments, were found to show a large magnetic-field-induced volume\nincrease approaching 500 ppm by applying a magnetic field of 9 T. This large\nvolume increase appeared only at around 30 K. At 30 K, a spin-reorientation\ntransition from ferrimagnetic to conical order occurs, giving rise to this\nlarge volume increase. The coexistence of ferrimagnetic and conical phases at\nthis transition was found to be important, suggesting that such a large\nmagnetic-field-induced volume change can be realized at various magnetic\ntransitions in localized magnets with strong spin-lattice coupling.",
        "positive": "Time-dependent density functional theory of high-intensity, short-pulse\n  laser irradiation on insulators: We calculate the energy deposition by very short laser pulses in SiO_2\n(alpha-quartz) with a view to establishing systematics for predicting damage\nand nanoparticle production. The theoretical framework is time-dependent\ndensity functional theory, implemented by the real-time method in a multiscale\nrepresentation. For the most realistic simulations we employ a meta-GGA\nKohn-Sham potential similar to that of Becke and Johnson. We find that the\ndeposited energy in the medium can be accurately modeled as a function of the\nlocal electromagnetic pulse fluence. The energy-deposition function can in turn\nbe quite well fitted to the strong-field Keldysh formula for a range of\nintensities from below the melting threshold to well beyond the ablation\nthreshold. We find reasonable agreement between the damage threshold and the\nenergy required to melt the substrate. The ablation threshold estimated by the\nenergy to convert the substrate to an atomic fluid is higher than the\nmeasurement, indicating significance of nonthermal nature of the process. A\nfair agreement is found for the depth of the ablation."
    },
    {
        "anchor": "Thermal Effects in Photoemission and Electron-Phonon Couplings of\n  Fullerene: We show that thermal effects play a relevant role in the determination of the\nelectron-phonon couplings based on the intensity of the phonon-shakeup peaks in\nphotoemission spectra. In particular, we re-consider the determination of the\nelectron-phonon couplings of fullerene based on a fit of the photoemission\nspectrum of C60- in gas phase [Gunnarsson PRB 1995]. We show that taking\nthermal effects into account reduces the obtained couplings by approximately\n10%.",
        "positive": "Topology of the Spin-polarized Charge Density in bcc and fcc Iron: We investigate the topology of the spin-polarized charge density in bcc and\nfcc iron. While the total spin-density is found to possess the topology of the\nnon-magnetic prototypical structures, in some cases the spin-polarized\ndensities are characterized by unique topologies; for example, the\nspin-polarized charge densities of bcc and high-spin fcc iron are atypical of\nany known for non-magnetic materials. In these cases, the two spin-densities\nare correlated: the spin-minority electrons have directional bond paths with\ndeep minima in the minority density, while the spin-majority electrons fill\nthese holes, reducing bond directionality. The presence of two distinct spin\ntopologies suggests that a well-known magnetic phase transition in iron can be\nfruitfully reexamined in light of these topological changes. We show that the\ntwo phase changes seen in fcc iron (paramagnetic to low-spin and low-spin to\nhigh-spin) are different. The former follows the Landau symmetry-breaking\nparadigm and proceeds without a topological transformation, while the latter\nalso involves a topological catastrophe."
    },
    {
        "anchor": "Effect of heterostructure engineering on electronic structure and\n  transport properties of two-dimensional halide perovskites: Organic-inorganic halide perovskite solar cells have attracted much attention\ndue to their low-cost fabrication, flexibility, and high-power conversion\nefficiency. More recent efforts show that the reduction from three- to\ntwo-dimensions (2D) of organic-inorganic halide perovskites promises an\nexciting opportunity to tune their electronic properties. Here, we explore the\neffect of reduced dimensionality and heterostructure engineering on the\nintrinsic material properties, such as energy stability, bandgap and transport\nproperties of 2D hybrid organic-inorganic halide perovskites using\nfirst-principles density functional theory. We show that the energetic\nstability is significantly enhanced by engineered perovskite heterostructures\nthat also possess excellent transport properties similar to their bulk\ncounterparts. These layered chemistries also demonstrate the advantage of a\nbroad range of tunable bandgaps and high-absorption coefficient in the visible\nspectrum. The proposed 2D heterostructured material holds potential for\nnano-optoelectronic devices as well as for effective photovoltaics.",
        "positive": "First principles study on the mechanism of abnormal viscosity change of\n  pure Al & Pb melts based on Wulff cluster model: In this paper, the Wulff cluster model combined phonon calculation is used to\ninvestigate the relationship between the structure of metallic melts (Pb/Al)\nand the abnormal viscosity change. Although absolute value of the surface\nenergy does not change significantly with temperature, the Wulff shape changed\nevidently. When temperature raise to 975K, Pb(321) surface that has the highest\ninteraction strength completely disappears, while the abnormal viscosity drop\nhappens at the same temperature range. Oppositely, Al(100) surface that has the\nlowest interaction strength disappears when temperature is higher than 1075K,\nand at the same temperature range, the abnormal viscosity rise has been\nobserved. The abnormal viscosity drop corresponds to the disappearance of\nsurface with the highest interaction strength (Pb(321) surface), while the rise\none corresponds to the disappearance of surface with the lowest adsorption\nenergy (Al(100) surface). All evidence indicates that the uniformity between\nabnormal viscosity change and the change of Wulff shape is not a coincidence. A\npossible mechanism of the abnormal viscosity change is that it caused by the\nsignificant structure change of cluster (short range ordering) in the metallic\nmelts."
    },
    {
        "anchor": "Formation of zero-field Skyrmion arrays in asymmetric superlattices: We demonstrate the formation of metastable N\\'eel-type skyrmion arrays in\nPt/Co/Ni/Ir multi-layers at zero-field following \\textit{ex situ} application\nof an in-plane magnetic field using Lorentz transmission electron microscopy.\nThe resultant skyrmion texture is found to depend on both the strength and\nmisorientation of the applied field as well as the interfacial\nDzyaloshinskii-Moriya interaction. To demonstrate the importance of the applied\nfield angle, we leverage bend contours in the specimens which coincide with\ntransition regions between skyrmion and labyrinth patterns. Subsequent\napplication of a perpendicular magnetic field near these regions reveals the\nunusual situation where skyrmions with opposite magnetic polarities are\nstabilized in close proximity.",
        "positive": "Kinetic Processes and surfactant design of Group I elements on CZTS\n  (1-1-2-) surface: Cu2ZnSnS4 (CZTS) is a promising thin-film solar-cell material consisted of\nearth abundant and nontoxic elements. Yet, there exists a fundamental bottle\nneck that hinders the performance of the device due to complexed intrinsic\ndefects properties and detrimental secondary phases. Recently, it was proven\nexperimentally that Na and K in co-evaporation growth of CZTS can enlarge the\ngrain size and suppress formation of ZnS secondary phase near surface, but the\nreasons are not well understood. We used first principle calculations to\ninvestigate the kinetic processes on CZTS (1-1-2-) surface involving Group I\nelements, including Na, K, and Cs, to demonstrate their surfactant effects.\nBoth the structure of the reconstructed surfaces involving Group I elements and\nvarious diffusion paths of a Zn ad-atom in these reconstructed surfaces were\nexplored. The advantages and concerns of the surfactant effects of Na, K, Cs,\nwere systematically compared and discussed. Although Group I elements protect\nCu sites on the subsurface layer, a disordered metastable configuration with a\ndiffusion barrier of about 400meV was found. Therefore, a precise control of\ngrowth condition is essential to avoid the metastable phase. In addition, our\nstudies provide a systematical design principle for surfactant effects during\nthe growth."
    },
    {
        "anchor": "Cross talk by extensive domain wall motion in arrays of ferroelectric\n  nanocapacitors: We report on extensive domain wall motion in ferroelectric nanocapacitor\narrays investigated by piezoresponse force microscopy. Under a much longer or\nhigher bias voltage pulse, compared to typical switching pulse conditions,\ndomain walls start to propagate into the neighbouring capacitors initiating a\nsignificant cross-talk. The propagation paths and the propagated area into the\nneighbouring capacitors were always the same under repeated runs. The\nexperimental and the simulated results show that the observed cross-talk is\nrelated to the capacitor parameters combined with local defects. The results\ncan be helpful to test the reliability of nanoscale ferroelectric memory\ndevices.",
        "positive": "Quasiparticle energies for large molecules: a tight-binding GW approach: We present a tight-binding based GW approach for the calculation of\nquasiparticle energy levels in confined systems such as molecules. Key\nquantities in the GW formalism like the microscopic dielectric function or the\nscreened Coulomb interaction are expressed in a minimal basis of spherically\naveraged atomic orbitals. All necessary integrals are either precalculated or\napproximated without resorting to empirical data. The method is validated\nagainst first principles results for benzene and anthracene, where good\nagreement is found for levels close to the frontier orbitals. Further, the size\ndependence of the quasiparticle gap is studied for conformers of the polyacenes\n($C_{4n+2}H_{2n+4}$) up to n = 30."
    },
    {
        "anchor": "Optical properties of Mn4+ ions in GaN:Mn codoped with Mg acceptors: The optical properties of Mn-Mg codoped epitaxial GaN were studied. Addition\nof Mg acceptors quenches the weak manganese-related photoluminescence (PL) band\nat 1.3 eV in GaN:Mn and a series of sharp PL peaks are observed at 1 eV in\ncodoped epilayers. The change in PL spectra indicates that Mg addition\nstabilizes the Mn4+ charge state by decreasing the Fermi level. The 1 eV PL\npeaks are tentatively attributed to intra center transitions involving Mn4+\nions. Spin allowed 3d-shell 4T2-4T1 transitions and their phonon replicas are\ninvolved. The relative intensities of the sharp peaks are strongly dependent on\nthe excitation wavelength, indicating the optically active Mn4+ centers\ninvolved in the separate peaks are different. The temperature dependence of the\nPL spectrum suggests the presence of at least three distinct Mn4+ complex\ncenters.",
        "positive": "Correlation between magnetism and magnetocaloric effect in RCo2-based\n  Laves phase compounds: By virtue of the itinerant electron metamagnetism (IEM), the RCo2 compounds\nwith R=Er, Ho and Dy are found to show first order magnetic transition at their\nordering temperatures. The inherent instability of Co sublattice magnetism is\nresponsible for the occurrence of IEM, which leads to interesting magnetic and\nrelated properties. The systematic studies of the variations in the magnetic\nand magnetocaloric properties of the RCo2-based compounds show that the\nmagnetovolume effect plays a decisive role in determining the nature of\nmagnetic transitions and hence the magnetocaloric effect (MCE) in these\ncompound. It is found that the spin fluctuations arising due to the\nmagnetovolume effect reduce the strength of IEM in these compounds, which\nsubsequently lead to a reduction in the MCE. Most of the substitutions at the\nCo site are found to result in a positive magnetovolume effect, leading to an\ninitial increase in the ordering temperature. Application of pressure, on the\nother hand, causes a reduction in the ordering temperature due to the negative\nmagnetovolume effect. A comparative study of the magnetic and magnetocaloric\nproperties of RCo2 compounds under various substitutions and applied pressure\nis presented. Analysis of the magnetization data using the Landau theory has\nshown that there is a strong correlation between the Landau coefficient (B) and\nthe MCE. The variations seen in the order of magnetic transition and the MCE\nvalues seem to support the recent model proposed by Khmelevskyi and Mohn for\nthe occurrence of IEM in RCo2 compounds."
    },
    {
        "anchor": "Quenched pinning and collective dislocation dynamics: Several experiments show that crystalline solids deform in a bursty and\nintermittent fashion. Power-law distributed strain bursts in compression\nexperiments of micron-sized samples, and acoustic emission energies from\nlarger-scale specimens, are the key signatures of the underlying critical-like\ncollective dislocation dynamics - a phenomenon that has also been seen in\ndiscrete dislocation dynamics (DDD) simulations. Here we show, by performing\nlarge-scale two-dimensional DDD simulations, that the character of the\ndislocation avalanche dynamics changes upon addition of sufficiently strong\nrandomly distributed quenched pinning centres, present e.g. in many alloys as\nimmobile solute atoms. For intermediate pinning strength, our results adhere to\nthe scaling picture of depinning transitions, in contrast to pure systems where\ndislocation jamming dominates the avalanche dynamics. Still stronger disorder\nquenches the critical behaviour entirely.",
        "positive": "Microscopic Origin of the Electric Dzyaloshinskii-Moriya Interaction: The microscopic origin of the electric Dzyaloshinskii-Moriya interaction\n(eDMI) is unveiled and discussed by analytical analysis and first-principles\nbased calculations. As similar to the magnetic Dzyaloshinskii-Moriya\ninteraction (mDMI), eDMI also originates from electron-mediated effect and more\nspecifically from certain electron hoppings that are being activated due to\ncertain local inversion symmetry breaking. However, the eDMI energy is found to\nbe at least a third-order interaction in atomic displacements instead of\nbilinear in magnetic dipole moments for mDMI. Furthermore, the eDMI energy form\nis presented, and we find that novel electrical topological defects (namely,\nchiral electric bobbers) can arise from this eDMI. Thus unraveling the\nmicroscopic origin of eDMI has the potential to lead to, and explain, the\ndiscovery of novel polar topological phases."
    },
    {
        "anchor": "Single scan STEM-EMCD in 3-beam orientation using a quadruple aperture: The need to acquire multiple angle-resolved electron energy loss spectra\n(EELS) is one of the several critical challenges associated with electron\nmagnetic circular dichroism (EMCD) experiments. If the experiments are\nperformed by scanning a nanometer to atomic-sized electron probe on a specific\nregion of a sample, the precision of the local magnetic information extracted\nfrom such data highly depends on the accuracy of the spatial registration\nbetween multiple scans. For an EMCD experiment in a 3-beam orientation, this\nmeans that the same specimen area must be scanned four times while keeping all\nthe experimental conditions same. This is a non-trivial task as there is a high\nchance of morphological and chemical modification as well as non-systematic\nlocal orientation variations of the crystal between the different scans due to\nbeam damage, contamination and spatial drift. In this work, we employ a\ncustom-made quadruple aperture to acquire the four EELS spectra needed for the\nEMCD analysis in a single electron beam scan, thus removing the above-mentioned\ncomplexities. We demonstrate a quantitative EMCD result for a beam convergence\nangle corresponding to sub-nm probe size and compare the EMCD results for\ndifferent detector geometries.",
        "positive": "Surface reconstruction, premelting, and collapse of open-cell nanoporous\n  Cu via thermal annealing: We systematic investigate the collapse of a set of open-cell nanoporous Cu\n(np-Cu) with the same porosity and shapes, but different specific surface area,\nduring thermal annealing, via performing large-scale molecular dynamics\nsimulations. Surface premelting is dominated in their collapses, and surface\npremelting temperatures reduce linearly with the increase of specific surface\narea. The collapse mechanisms are different for np-Cu with different specific\nsurface area. If the specific surface area less than a critical value ($\\sim$\n2.38 nm$^{-1}$), direct surface premelting, giving rise to the transition of\nligaments from solid to liquid states, is the cause to facilitate falling-down\nof np-Cu during thermal annealing. While surface premelting and following\nrecrystallization, accelerating the sloughing of ligaments and annihilation of\npores, is the other mechanism, as exceeding the critical specific surface area.\nThe recrystallization occurs at the temperatures below supercooling, where\nliquid is instable and instantaneous. Thermal-induced surface reconstruction\nprompts surface premelting via facilitating local \"disordering\" and \"chaotic\"\nat the surface, which are the preferred sites for surface premelting."
    },
    {
        "anchor": "Dynamics of self-dual kagome metamaterials and the emergence of fragile\n  topology: Recent years have seen the discovery of systems featuring fragile topological\nstates. These states of matter lack certain protection attributes typically\nassociated with topology and are therefore characterized by weaker signatures\nthat make them elusive to observe. Moreover, they are typically confined to\nspecial symmetry classes and, in general, rarely studied in the context of\nphononic media. In this article, we theoretically predict the emergence of\nfragile topological bands in the spectrum of a twisted kagome elastic lattice\nwith three-fold rotational symmetry, in the so-called self-dual configuration.\nA necessary requirement is that the lattice is a structural metamaterial, in\nwhich the role of the hinges is played by elastic finite-thickness ligaments.\nThe interplay between the edge modes appearing in the bandgaps bounding the\nfragile topological states is also responsible for the emergence of corner\nmodes at selected corners of a finite hexagonal domain, which qualifies the\nlattice as a second-order topological insulator. We demonstrate our findings\nthrough a series of experiments via 3D Scanning Laser Doppler Vibrometry\nconducted on a physical prototype. The selected configuration stands out for\nits remarkable geometric simplicity and ease of physical implementation in the\npanorama of dynamical systems exhibiting fragile topology.",
        "positive": "Improved topological conformity enhances heat conduction across metal\n  contacts on transferred graphene: Thermal conductance of metal contacts on transferred graphene (trG) could be\nsignificantly reduced from the intrinsic value of similar contacts on as-grown\ngraphene (grG), due to additional resistance by increased roughness, residues,\noxides and voids. In this paper, we compare the thermal conductance (G) of\nAl/trG/Cu interfaces with that of Al/grG/Cu interfaces to understand heat\ntransfer across metal contacts on transferred graphene. Our samples are\npolycrystalline graphene grown on Cu foils by chemical vapor deposition (CVD)\nand CVD-grown graphene transferred to evaporated Cu thin films. We find that\nfor the Al/grG/Cu interfaces of as-grown CVD graphene, G=31 MW m^{-2} K^{-1} at\nroom temperature, two orders of magnitude lower than that of Al/Cu interfaces.\nFor most as-transferred graphene on Cu films, G=20 MW m^{-2} K^{-1}, 35% lower\nthan that of as-grown CVD graphene. We carefully rule out the contributions of\nresidues, native oxides and interfaces roughness, and attribute the difference\nin the thermal conductance of as-grown and as-transferred CVD graphene to\ndifferent degrees of conformity of graphene to the Cu substrates. We find that\na contact area of 50% only reduces the thermal conductance by 35%, suggesting\nthat a small amount of heat transfer occurs across voids at graphene\ninterfaces. We successfully improve the conformity of the as-transferred\ngraphene to the substrates by annealing the samples at 300{\\deg}C, and thus\nenhance the thermal conductance of the transferred graphene to the intrinsic\nvalue. From the temperature dependence measurements of G of Al/trG/Cu and\nAl/grG/Cu interfaces, we also confirm that phonons are the dominant heat\ncarries across the metal/graphene/metal interfaces despite a substantial\ncarrier concentration of 3x10^{12} cm^{-2} induced in the graphene."
    },
    {
        "anchor": "Structures and stability of the Cu$_{38}$ cluster at finite temperature: The UV-visible and IR properties of the Cu$_{38}$ nanocluster depend to a\ngreat extent on the temperature. Density functional theory and\nnanothermodynamics can be combined to compute the geometrical optimization of\nisomers and their spectroscopic properties in an approximate manner. In this\narticle, we investigate entropy-driven isomer distributions of Cu$_{38}$\nclusters and the effect of temperature on their UV-visible and IR spectra. An\nextensive, systematic global search is performed on the potential and free\nenergy surfaces of Cu38 using a two-stage strategy to identify the\nlowest-energy structure and its low-energy neighbors. The effects of\ntemperature on the UV and IR spectra are considered via Boltzmann probability.\nThe computed UV-visible and IR spectrum of each isomer is multiplied by its\ncorresponding Boltzmann weight at finite temperature. Then, they are summed\ntogether to produce a final temperature-dependent, Boltzmann-weighted\nUV-visible and IR spectrum. Additionally, Molecular Dynamics simulation of the\nCu$_{38}$ nanocluster was performed to gain insight into the system dynamics\nand make a three-dimensional movie of the system with atomistic resolution. Our\nresults show the thermal populations at the absolute temperature of Cu38\ncluster, and the disordered structure that dominates at high temperatures.",
        "positive": "Reference electronic structure calculations in one dimension: Large strongly correlated systems provide a challenge to modern electronic\nstructure methods, because standard density functionals usually fail and\ntraditional quantum chemical approaches are too demanding. The density-matrix\nrenormalization group method, an extremely powerful tool for solving such\nsystems, has recently been extended to handle long-range interactions on\nreal-space grids, but is most efficient in one dimension where it can provide\nessentially arbitrary accuracy. Such 1d systems therefore provide a theoretical\nlaboratory for studying strong correlation and developing density functional\napproximations to handle strong correlation, {\\em if} they mimic\nthree-dimensional reality sufficiently closely. We demonstrate that this is the\ncase, and provide reference data for exact and standard approximate methods,\nfor future use in this area."
    },
    {
        "anchor": "Solubility in Zr-Nb alloys from first-principles: The thermodynamic properties of the Zr-Nb alloy are investigated at\ntemperatures below 890 K with ab initio calculations. The solution energies of\nthe bcc Nb-rich and hcp Zr-rich solid solutions obtained within the framework\nof density functional theory are in good agreement with experimental data,\nalthough insufficient for a quantitative description of the miscibility gap,\nfor which non configurational entropy has to be accounted for. Whereas\nelectronic free energies can be neglected, we show, using the harmonic\napproximation and the density functional perturbation theory, that both\nsolution free energies are strongly modified by the contribution related to\natomic vibrations. Considering this vibrational free energy leads to a good\ndescription of the phase diagram.",
        "positive": "A Class of Magnetic Topological Material Candidates with Hypervalent Bi\n  Chains: The link between crystal and electronic structure is crucial for\nunderstanding structure-property relations in solid-state chemistry. In\nparticular, it has been instrumental in understanding topological materials,\nwhere electrons behave differently than they would in conventional solids.\nHerein, we identify 1D Bi chains as a structural motif of interest for\ntopological materials. We focus on Sm$_3$ZrBi$_5$, a new quasi-one-dimensional\n(1D) compound in the Ln$_3$MPn$_5$ (Ln = lanthanide; M = metal; Pn = pnictide)\nfamily that crystallizes in the P$6_{3}$/mcm space group. Density functional\ntheory calculations indicate a complex, topologically non-trivial electronic\nstructure that changes significantly in the presence of spin-orbit coupling.\nMagnetic measurements show a quasi-1D antiferromagnetic structure with two\nmagnetic transitions at 11.7 and 10.7 K that are invariant to applied field up\nto 9 T, indicating magnetically frustrated spins. Heat capacity, electrical,\nand thermal transport measurements support this claim and suggest complex\nscattering behavior in Sm$_3$ZrBi$_5$. This work highlights 1D chains as an\nunexplored structural motif for identifying topological materials, as well as\nthe potential for rich physical phenomena in the Ln$_3$MPn$_5$ family."
    },
    {
        "anchor": "Tuning carrier density and phase transitions in oxide semiconductors\n  using focused ion beams: We demonstrate spatial modification of the optical properties of thin-film\nmetal oxides, zinc oxide and vanadium dioxide as representatives, using a\ncommercial focused ion beam (FIB) system. Using a Ga+ FIB and thermal\nannealing, we demonstrated variable doping of a band semiconductor, zinc oxide\n(ZnO), achieving carrier concentrations from 10^18 cm-3 to 10^20 cm-3. Using\nthe same FIB without subsequent thermal annealing, we defect-engineered a\ncorrelated semiconductor, vanadium dioxide (VO2), locally modifying its\ninsulator-to-metal transition (IMT) temperature by range of ~25 degrees C. Such\narea-selective modification of metal oxides by direct writing using a FIB\nprovides a simple, mask-less route to the fabrication of optical structures,\nespecially when multiple or continuous levels of doping or defect density are\nrequired.",
        "positive": "Flexoelectricity from density-functional perturbation theory: We derive the complete flexoelectric tensor, including electronic and\nlattice-mediated effects, of an arbitrary insulator in terms of the microscopic\nlinear response of the crystal to atomic displacements. The basic ingredient,\nwhich can be readily calculated from first principles in the framework of\ndensity-functional perturbation theory, is the quantum-mechanical probability\ncurrent response to a long-wavelength acoustic phonon. Its second-order Taylor\nexpansion in the wavevector q around the Gamma (q=0) point in the Brillouin\nzone naturally yields the flexoelectric tensor. At order one in q we recover\nMartin's theory of piezoelectricity [R. M. Martin, Phys. Rev. B 5, 1607\n(1972)], thus providing an alternative derivation thereof. To put our\nderivations on firm theoretical grounds, we perform a thorough analysis of the\nnonanalytic behavior of the dynamical matrix and other response functions in a\nvicinity of Gamma. Based on this analysis, we find that there is an ambiguity\nin the specification of the \"zero macroscopic field\" condition in the\nflexoelectric case; such arbitrariness can be related to an analytic\nband-structure term, in close analogy to the theory of deformation potentials.\nAs a byproduct, we derive a rigorous generalization of the Cochran-Cowley\nformula [W. Cochran and R. A. Cowley, J. Phys. Chem. Solids 23, 447 (1962)] to\nhigher orders in q. This can be of great utility in building reliable atomistic\nmodels of electromechanical phenomena, as well as for improving the accuracy of\nthe calculation of phonon dispersion curves. Finally, we discuss the physical\ninterpretation of the various contributions to the flexoelectric response,\neither in the static or dynamic regime."
    },
    {
        "anchor": "Current-driven Magnetization Reversal in a Ferromagnetic Semiconductor\n  (Ga,Mn)As/GaAs/(Ga,Mn)As Tunnel Junction: Current-driven magnetization reversal in a ferromagnetic semiconductor based\n(Ga,Mn)As/GaAs/(Ga,Mn)As magnetic tunnel junction is demonstrated at 30 K.\nMagnetoresistance measurements combined with current pulse application on a\nrectangular 1.5 x 0.3 um^2 device revealed that magnetization switching occurs\nat low critical current densities of 1.1 - 2.2 x 10^5 A/cm^2 despite the\npresence of spin-orbit interaction in the p-type semiconductor system. Possible\nmechanisms responsible for the effect are discussed.",
        "positive": "Longitudinal muon spin relaxation in high purity aluminum and silver: The time dependence of muon spin relaxation has been measured in high purity\naluminum and silver samples in a longitudinal 2 T magnetic field at room\ntemperature, using time-differential \\musr. For times greater than 10 ns, the\nshape fits well to a single exponential with relaxation rates of\n$\\lambda_{\\textrm{Al}} = 1.3 \\pm 0.2\\,(\\textrm{stat.}) \\pm\n0.3\\,(\\textrm{syst.})\\,\\pms$ and $\\lambda_{\\textrm{Ag}} = 1.0 \\pm\n0.2\\,(\\textrm{stat.}) \\pm 0.2\\,(\\textrm{syst.})\\,\\pms$."
    },
    {
        "anchor": "Magnetotransport in semiconductors and two-dimensional materials from\n  first principles: We demonstrate a first-principles method to study magnetotransport in\nmaterials by solving the Boltzmann transport equation (BTE) in the presence of\nan external magnetic field. Our approach employs ab initio electron-phonon\ninteractions and takes spin-orbit coupling into account. We apply our method to\nvarious semiconductors (Si and GaAs) and two-dimensional (2D) materials\n(graphene) as representative case studies. The magnetoresistance, Hall mobility\nand Hall factor in Si and GaAs are in very good agreement with experiments. In\ngraphene, our method predicts a large magnetoresistance, consistent with\nexperiments. Analysis of the steady-state electron occupations in graphene\nshows the dominant role of optical phonon scattering and the breaking of the\nrelaxation time approximation. Our work provides a detailed understanding of\nthe microscopic mechanisms governing magnetotransport coefficients,\nestablishing the BTE in a magnetic field as a broadly applicable\nfirst-principles tool to investigate transport in semiconductors and 2D\nmaterials.",
        "positive": "Nano-Hall sensors with granular Co-C: We analyzed the performance of Hall sensors with different Co-C ratios,\ndeposited directly in nano-structured form, using $Co_2(CO)_8$ gas molecules,\nby focused electron or ion beam induced deposition. Due to the enhanced\ninter-grain scattering in these granular wires, the Extraordinary Hall Effect\ncan be increased by two orders of magnitude with respect to pure Co, up to a\ncurrent sensitivity of $1 \\Omega/T$. We show that the best magnetic field\nresolution at room temperature is obtained for Co ratios between 60% and 70%\nand is better than $1 \\mu T/Hz^{1/2}$. For an active area of the sensor of $200\n\\times 200 nm^2$, the room temperature magnetic flux resolution is $\\phi_{min}\n= 2\\times10^{-5}\\phi_0$, in the thermal noise frequency range, i.e. above 100\nkHz."
    },
    {
        "anchor": "Strong 1D localization and highly anisotropic electron-hole masses in\n  heavy-halogen functionalized graphenes: While halogenation of graphene presents a fascinating avenue to the\nconstruction of a chemically and physically diverse class of systems, their\napplication in photovoltaics has been hindered by often prohibitively large\noptical gaps. Herein we study the effects of partial bromination and\nchlorination on the structure and optoelectronic properties of both graphane\nand fluorographene. We find brominated and chlorinated fluorographene\nderivatives to be as stable as graphane making them likely to be durable even\nat elevated temperatures. A detailed investigation of the systems band\nstructure reveals significant 1D localization of the charge carriers as well as\nstrongly electron-hole asymmetric effective masses. Lastly using $G_0W_0$ and\nBSE, we investigate the optical adsorption spectra of the aforementioned\nmaterials whose first adsorption peak is shown to lie close to the optimal peak\nposition for photovoltaic applications ($\\approx 1.5$ eV).",
        "positive": "Incorporating point defect generation due to jog formation into the\n  vector density-based continuum dislocation dynamics approach: During plastic deformation of crystalline materials, point defects such as\nvacancies and interstitials are generated by jogs on moving dislocations. A\ndetailed model for jog formation and transport during plastic deformation was\ndeveloped within the vector density-based continuum dislocation dynamics\nframework (Lin and El-Azab, 2020; Xia and El-Azab, 2015). As a part of this\nmodel, point defect generation associated with jog transport was formulated in\nterms of the volume change due to the non-conservative motion of jogs. Balance\nequations for the vacancies and interstitials including their rate of\ngeneration due to jog transport were also formulated. A two-way coupling\nbetween point defects and dislocation dynamics was then completed by including\nthe stress contributed by the eigen-strain of point defects. A jog drag stress\nwas further introduced into the mobility law of dislocations to account for the\nenergy dissipation during point defects generation. A number of test problems\nand a fully coupled simulation of dislocation dynamics and point defect\ngeneration and diffusion were performed. The results show that there is an\nasymmetry of vacancy and interstitial generation due to the different formation\nenergies of the two types of defects. The results also show that a higher\nhardening rate and a higher dislocation density are obtained when the point\ndefect generation mechanism is coupled to dislocation dynamics."
    },
    {
        "anchor": "Epitaxial binding and strain effects of monolayer stanene on the\n  Al$_{2}$O$_{3}$(0001) surface: Stanene, the two-dimensional monolayer form of tin, has been predicted to be\na 2D topological insulator due to its large spin--orbit interaction. However, a\nclear experimental demonstration of stanene's topologically nontrivial\nproperties has eluded observation, in part because of the difficulty of\nchoosing a substrate on which stanene will remain topologically nontrivial. In\nthis paper, we present first-principles density functional theory (DFT)\ncalculations of epitaxial monolayer stanene grown on the (0001) surface of\nalumina, Al$_{2}$O$_{3}$, as well as free-standing decorated stanene under\nstrain. By describing the energetics and nature of how monolayer stanene binds\nto alumina, we show a strong energetic drive for the monolayer to be coherently\nstrained and epitaxial to the substrate. By analyzing the electronic structure\nof strained stanene, we find it to be a quantum spin Hall insulator on\nAl$_{2}$O$_{3}$. We also describe the effect of \\emph{in situ} fluorine\ndecoration on the bound stanene monolayer, including on its potential for\nmechanical exfoliation.",
        "positive": "Revealing contributions to conduction from transport within ordered and\n  disordered regions in highly doped conjugated polymers through analysis of\n  temperature-dependent Hall measurements: Hall effect measurements in doped polymer semiconductors are widely reported,\nbut are difficult to interpret due to screening of Hall voltages by carriers\nundergoing incoherent transport. Here, we propose a refined analysis for such\nHall measurements, based on measuring the Hall coefficient as a function of\ntemperature, and modelling carriers as existing in a regime of variable\n\"deflectability\" (i.e. how strongly they \"feel\" the magnetic part of the\nLorentz force). By linearly interpolating each carrier between the extremes of\nno deflection and full deflection, we demonstrate that it is possible to\nextract the (time-averaged) concentration of deflectable charge carriers,\n$\\left<n_d\\right>$, the average, temperature-dependent mobility of those\ncarriers, $\\left<\\mu_d\\right>(T)$, as well as the ratio of conductivity that\ncomes from such deflectable transport, $d(T)$. Our method was enabled by the\nconstruction of an improved AC Hall measurement system, as well as an improved\ndata extraction method. We measured Hall bar devices of ion-exchange doped\nfilms of PBTTT-C$_{14}$ from 10--300 K. Our analysis provides evidence for the\nproportion of conductivity arising from deflectable transport, $d(T)$,\nincreasing with doping level, ranging between 15.4% and 16.4% at room\ntemperature. When compared to total charge-carrier-density estimates from\nindependent methods, the values of $\\left<n_d\\right>$ extracted suggest that\ncarriers spend $\\sim$37% of their time of flight being deflectable in the most\nhighly doped of the devices measured here. The extracted values of $d(T)$ being\nless than half this value thus suggest that the limiting factor for\nconductivity in such highly doped devices is carrier mobility, rather than\nconcentration."
    },
    {
        "anchor": "Quantifying Capacity Loss due to Solid-Electrolyte-Interphase Layer\n  Formation on Silicon Negative Electrodes in Lithium-ion Batteries: Charge lost per unit surface area of a silicon electrode due to the formation\nof solid-electrolyte-interphase (SEI) layer during initial lithiation was\nquantified, and the species that constitute this layer were identified. Coin\ncells made with Si thin-film electrodes were subjected to a combination of\ngalvanostatic and potentiostatic lithiation and delithiation cycles to\naccurately measure the capacity lost to SEI-layer formation. While the planar\ngeometry of amorphous thin films allows accurate calculation of surface area,\ncreation of additional surface by cracking was prevented by minimizing the\nthickness of the Si film. The cycled electrodes were analyzed with X-ray\nphotoelectron spectroscopy to characterize the composition of the SEI layer.\nThe charge lost due to SEI formation measured from coin cell experiments was\nfound to be in good agreement with the first-cycle capacity loss during the\ninitial lithiation of a Si (100) crystal with planar geometry. The methodology\npresented in this work is expected to provide a useful practical tool for\nbattery-material developers in estimating the expected capacity loss due to\nfirst cycle SEI-layer formation and in choosing an appropriate particle size\ndistribution that balances mechanical integrity and the first cycle capacity\nloss in large volume expansion electrodes for lithium-ion batteries.",
        "positive": "Field-Driven Domain-Wall Dynamics in GaMnAs Films with Perpendicular\n  Anisotropy: We combine magneto-optical imaging and a magnetic field pulse technique to\nstudy domain wall dynamics in a ferromagnetic (Ga,Mn)As layer with\nperpendicular easy axis. Contrary to ultrathin metallic layers, the depinning\nfield is found to be smaller than the Walker field, thereby allowing for the\nobservation of the steady and precessional flow regimes. The domain wall width\nand damping parameters are determined self-consistently. The damping, 30 times\nlarger than the one deduced from ferromagnetic resonance, is shown to\nessentially originate from the non-conservation of the magnetization modulus.\nAn unpredicted damping resonance and a dissipation regime associated with the\nexistence of horizontal Bloch lines are also revealed."
    },
    {
        "anchor": "Topologically Invariant Double Dirac States in Bismuth based\n  Perovskites: Consequence of Ambivalent Charge States and Covalent Bonding: Bulk and surface electronic structures, calculated using density functional\ntheory and a tight-binding model Hamiltonian, reveal the existence of two\ntopologically invariant (TI) surface states in the family of cubic Bi\nperovskites (ABiO$_3$; A = Na, K, Rb, Cs, Mg, Ca, Sr and Ba). The two TI\nstates, one lying in the valence band (TI-V) and other lying in the conduction\nband (TI-C) are formed out of bonding and antibonding states of the\nBi-$\\{$s,p$\\}$ - O-$\\{$p$\\}$ coordinated covalent interaction. Below a certain\ncritical thickness of the film, which varies with A, TI states of top and\nbottom surfaces couple to destroy the Dirac type linear dispersion and\nconsequently to open surface energy gaps. The origin of s-p band inversion,\nnecessary to form a TI state, classifies the family of ABiO$_3$ into two. For\nclass-I (A = Na, K, Rb, Cs and Mg) the band inversion, leading to TI-C state,\nis induced by spin-orbit coupling of the Bi-p states and for class-II (A = Ca,\nSr and Ba) the band inversion is induced through weak but sensitive second\nneighbor Bi-Bi interactions.",
        "positive": "Observation of Various and Spontaneous Magnetic Skyrmionic Bubbles at\n  Room-Temperature in a Frustrated Kagome Magnet with Uniaxial Magnetic\n  Anisotropy: Various and spontaneous magnetic skyrmionic bubbles are experimentally\nobserved for the first time, at room temperature in a frustrated kagome magnet\nFe3Sn2 with unixial magnetic anisotropy. The magnetization dynamics were\ninvestigated using in-situ Lorentz transmission electron microscopy, revealing\nthat the transformation between different magnetic bubbles and domains are via\nthe motion of Bloch lines driven by applied external magnetic field. The\nresults demonstrate that Fe3Sn2 facilitates a unique magnetic control of\ntopological spin textures at room temperature, making it a promising candidate\nfor further skyrmion-based spintronic devices."
    },
    {
        "anchor": "Relevance of Shear Transformations in the Relaxation of Supercooled\n  Liquids: While deeply supercooled liquids exhibit divergent viscosity and increasingly\nheterogeneous dynamics as the temperature drops, their structure shows only\nseemingly marginal changes. Understanding the nature of relaxation processes in\nthis dramatic slowdown is key for understanding the glass transition. Here, we\nshow by atomistic simulations that the heterogeneous dynamics of glass-forming\nliquids strongly correlate with the local residual plastic strengths along soft\ndirections computed in the initial inherent structures. The correlation\nincreases with decreasing temperature and is maximum in the vicinity of the\nrelaxation time. For the lowest temperature investigated, this maximum is\ncomparable with the best values from the literature dealing with the\nstructure-property relationship. However, the nonlinear probe of the local\nshear resistance in soft directions provides here a real-space picture of\nrelaxation processes. Our detection method of thermal rearrangements allows us\nto investigate the first passage time statistics and to study the scaling\nbetween the activation energy barriers and the residual plastic strengths.\nThese results shed new light on the nature of relaxations of glassy systems by\nemphasizing the analogy between the thermal relaxations in viscous liquids and\nthe plastic shear transformation in amorphous solids.",
        "positive": "First-principles materials design of high-performing bulk photovoltaics\n  with the LiNbO$_3$ structure: The bulk photovoltaic effect is a long-known but poorly understood\nphenomenon. Recently, however, the multiferroic bismuth ferrite has been\nobserved to produce strong photovoltaic response to visible light, suggesting\nthat the effect has been underexploited as well. Here we present three polar\noxides in the LiNbO$_3$ structure that we predict to have band gaps in the 1-2\neV range and very high bulk photovoltaic response: PbNiO$_3$,\nMg$_{1/2}$Zn$_{1/2}$PbO$_3$, and LiBiO$_3$. All three have band gaps determined\nby cations with $d^{10}s^0$ electronic configurations, leading to conduction\nbands composed of cation $s$-orbitals and O $p$-orbitals. This both\ndramatically lowers the band gap and increases the bulk photovoltaic response\nby as much as an order of magnitude over previous materials, demonstrating the\npotential for high-performing bulk photovoltaics."
    },
    {
        "anchor": "On the bonding environment of phosphorus in purified doped single-walled\n  carbon nanotubes: In this work, phosphorous-doped single-walled carbon nanotubes have been\nsynthesized by the thermal decomposition of trimethylphosphine using a\nhigh-vacuum chemical vapor deposition method. Furthermore, a modified\ndensity-gradient-ultracentrifugation process has been applied to carefully\npurify our doped material. The combined use of Raman and X-ray photoelectron\nspectroscopy allowed us to provide the first insight into the bonding\nenvironment of P incorporated into the carbon lattice, avoiding competing\nsignals arising from synthesis byproducts. This study represents the first step\ntoward the identification of the bonding configuration of P atoms when direct\nsubstitution takes place.",
        "positive": "Comparison of density functionals for nitrogen impurities in ZnO: Hybrid functionals and empirical correction schemes are compared to\nconventional semi-local density functional theory (DFT) calculations in order\nto assess the predictive power of these methods concerning the formation energy\nand the charge transfer level of impurities in the wide-gap semiconductor ZnO.\nWhile the generalized gradient approximation fails to describe the electronic\nstructure of the N impurity in ZnO correctly, methods that widen the band gap\nof ZnO by introducing additional non-local potentials yield the formation\nenergy and charge transfer level of the impurity in reasonable agreement with\nhybrid functional calculations. Summarizing the results obtained with different\nmethods, we corroborate earlier findings that the formation of substitutional N\nimpurities at the oxygen site in ZnO from N atoms is most likely slightly\nendothermic under oxygen-rich preparation conditions, and introduces a deep\nlevel more than 1eV above the valence band edge of ZnO. Moreover, the\ncomparison of methods elucidates subtle differences in the predicted electronic\nstructure, e.g. concerning the orientation of unoccupied orbitals in the\ncrystal field and the stability of the charged triplet state of the N impurity.\nFurther experimental or theoretical analysis of these features could provide\nuseful tests for validating the performance of DFT methods in their application\nto defects in wide-gap materials."
    },
    {
        "anchor": "Could face-centered cubic titanium in cold-rolled commercially-pure\n  titanium only be a Ti-hydride?: A face-centered cubic (FCC) phase in electro-polished specimens for\ntransmission electron microscopy of commercially pure titanium has sometimes\nbeen reported. Here, a combination of atom-probe tomography, scanning\ntransmission electron microscopy and low-loss electron energy loss spectroscopy\nis employed to study both the crystal structural and chemical composition of\nthis FCC phase. Our results prove that the FCC phase is actually a TiHx (x>1)\nhydride, and not a new allotrope of Ti, in agreement with previous reports. The\nformation of the hydride is discussed.",
        "positive": "Grain boundary phases in bcc metals: We report a computational discovery of novel grain boundary structures and\nmultiple grain boundary phases in elemental bcc tungsten. While grain boundary\nstructures created by the \\gamma-surface method as a union of two perfect half\ncrystals have been studied extensively, it is known that the method has\nlimitations and does not always predict the correct ground states. Here, we use\na newly developed computational tool, based on evolutionary algorithms, to\nperform a grand-canonical search of a high-angle symmetric tilt boundary in\ntungsten, and we find new ground states and multiple phases that cannot be\ndescribed using the conventional structural unit model. We use MD simulations\nto demonstrate that the new structures can coexist at finite temperature in a\nclosed system, confirming these are examples of different GB phases. The new\nground state is confirmed by first-principles calculations."
    },
    {
        "anchor": "Hexagonal supertetrahedral boron: A topological metal with multiple\n  spin-orbit-free emergent fermions: We predict a new three-dimensional (3D) boron allotrope based on systematic\nfirst-principles electronic structure calculations. This allotrope can be\nderived by substituting each carbon atom in a hexagonal diamond lattice with a\nB$_{4}$ tetrahedron and possesses the same space group $P6_{3}/mmc$ as\nhexagonal diamond, hence it is termed as H-boron. We show that H-boron has good\nstability and excellent mechanical property. Remarkably, we find that H-boron\nis a topological metal with rich types of spin-orbit-free emergent fermions,\nincluding semi-Dirac fermion, quadratic and linear triple-point fermion,\nnodal-line fermion, and nodal-surface fermion. We clarify their symmetry\nprotections and characterize them by constructing the corresponding low-energy\neffective models. Our work not only discovers a new boron allotrope with\nexcellent properties, it also offers a platform to explore interesting physics\nof new kinds of emergent fermions.",
        "positive": "Spatial Imaging of Charge Transport in Silicon at Low Temperature: We present direct imaging measurements of charge transport across a 1\ncm$\\times$ 1 cm$\\times$ 4 mm crystal of high purity silicon ($\\sim$20\nk$\\Omega$cm) at temperatures between 500 mK and and 5 K. We use these data to\ndetermine the intervalley scattering rate of electrons as a function of the\nelectric field applied along the $\\langle 111 \\rangle$ crystal axis, and we\npresent a phenomenological model of intervalley scattering that explains the\nconstant scattering rate seen at low-voltage for cryogenic temperatures. We\nalso demonstrate direct imaging measurements of effective hole mass anisotropy,\nwhich is strongly dependent on both temperature and electric field strength.\nThe observed effects can be explained by a warping of the valence bands for\ncarrier energies near the spin-orbit splitting energy in silicon."
    },
    {
        "anchor": "Diffusion-Limited Exciton-Exciton Annihilation in Carbon Nanotubes:\n  Theoretical Model and its Comparison with Nonlinear Photoluminescence\n  Experiment: This paper has been withdrawn by the author due to a necessity of further\nediting. (Will be resubmitted here or elsewhere in editted form.)",
        "positive": "Surface Energy Driven Grain Growth Model: FePt L10 Nanoparticles: We developed a grain growth model that is based on the energy minimisation of\nsurfaces with respect to the volume energy and the grain's environment. We used\nthe well-known FePt L1$_\\text{0}$ system to discover the physical factors that\ndrive the shape and size of FePt grains. It was found that the preferred growth\ndirections are along symmetry planes that are determined by the basic crystal\nand driven by surface energy minimisation. The model developed here can be used\nto predict a grain's growth and shape as a function of atomic number and\ncomposition. This means that by tailoring a grain's surface and grain\nboundaries the shape of the magnetic grains can be manipulated."
    },
    {
        "anchor": "Metric Description of Defects in Amorphous Materials: Classical elasticity is concerned with bodies that can be modeled as smooth\nmanifolds endowed with a reference metric that represents local equilibrium\ndistances between neighboring material elements. The elastic energy associated\nwith a configuration of a body in classical elasticity is the sum of local\ncontributions that arise from a discrepancy between the actual metric and the\nreference metric. In contrast, the modeling of defects in solids has\ntraditionally involved extra structure on the material manifold, notably\ntorsion to quantify the density of dislocations and non-metricity to represent\nthe density of point defects. We show that all the classical defects can be\ndescribed within the framework of classical elasticity using tensor fields that\nonly assume a metric structure. Specifically, bodies with singular defects can\nbe viewed as affine manifolds; both disclinations and dislocations are captured\nby the monodromy that maps curves that surround the loci of the defects into\naffine transformations. Finally, we show that two dimensional defects with\ntrivial monodromy are purely local in the sense that if we remove from the\nmanifold a compact set that contains the locus of the defect, the punctured\nmanifold can be isometrically embedded in Euclidean space.",
        "positive": "Low temperature reflectivity study of ZnO/(Zn,Mg)O quantum wells grown\n  on M-plane ZnO substrates: We report growth of high quality ZnO/Zn0.8Mg0.2O quantum well on M-plane\noriented ZnO substrates. The optical properties of these quantum wells are\nstudied by using reflectance spectroscopy. The optical spectra reveal strong\nin-plane optical anisotropies, as predicted by group theory, and marked\nreflectance structures, as an evidence of good interface morphologies.\nSignatures ofc onfined excitons built from the spin-orbit split-off valence\nband, the analog of exciton C in bulk ZnO are detected in normal incidence\nreflectivity experiments using a photon polarized along the c axis of the\nwurtzite lattice. Experiments performed in the context of an orthogonal photon\npolarization, at 90^{\\circ}; of this axis, reveal confined states analogs of A\nand B bulk excitons. Envelope function calculations which include excitonic\ninteraction nicely account for the experimental report."
    },
    {
        "anchor": "Electrically tuneable nonequilibrium optical response of graphene: The ability to tune the optical response of a material via electrostatic\ngating is crucial for optoelectronic applications, such as electro-optic\nmodulators, saturable absorbers, optical limiters, photodetectors and\ntransparent electrodes. The band structure of single layer graphene (SLG), with\nzero-gap, linearly dispersive conduction and valence bands, enables an easy\ncontrol of the Fermi energy E$_F$ and of the threshold for interband optical\nabsorption. Here, we report the tunability of the SLG non-equilibrium optical\nresponse in the near-infrared (1000-1700nm/0.729-1.240eV), exploring a range of\nE$_F$ from -650 to 250 meV by ionic liquid gating. As E$_F$ increases from the\nDirac point to the threshold for Pauli blocking of interband absorption, we\nobserve a slow-down of the photobleaching relaxation dynamics, which we\nattribute to the quenching of optical phonon emission from photoexcited charge\ncarriers. For E$_F$ exceeding the Pauli blocking threshold, photobleaching\neventually turns into photoinduced absorption, due to hot electrons' excitation\nincreasing SLG absorption. The ability to control both recovery time and sign\nof nonequilibrium optical response by electrostatic gating makes SLG ideal for\ntunable saturable absorbers with controlled dynamics.",
        "positive": "A New Method to Calculate Electromagnetic Impedance Matching Degree in\n  One-Layer Microwave Absorbers: A delta-function method was proposed to quantitatively evaluate the\nelectromagnetic impedance matching degree. Measured electromagnetic parameters\nof {\\alpha}-Fe/Fe3B/Y2O3 nanocomposites are applied to calculate the matching\ndegree by the method. Compared with reflection loss and quarter-wave principle\ntheory, the method accurately reveals the intrinsic mechanism of microwave\ntransmission and reflection properties. A possible honeycomb structure with\npromising high-performance microwave absorption according to the method is also\nproposed."
    },
    {
        "anchor": "Detection and measurement of the Dzyaloshinskii-Moriya interaction in\n  double quantum dot systems: Spins in quantum dots can act as the qubit for quantum computation. In this\ncontext we point out that spins on neighboring dots will experience an\nanisotropic form of the exchange coupling, called the Dzyaloshinskii-Moriya\n(DM) interaction, which mixes the spin singlet and triplet states. This will\nhave an important effect on both qubit interactions and spin-dependent\ntunneling. We show that the interaction depends strongly on the direction of\nthe external field, which gives an unambiguous signature of this effect. We\nfurther propose a new experiment using coupled quantum dots to detect and\ncharacterize the DM interaction.",
        "positive": "Triplon current generation in solids: A triplon refers to a fictitious particle that carries angular momentum $S =\n1$ corresponding to the elementary excitation in a broad class of quantum\ndimerized spin systems. Such systems without magnetic order have long been\nstudied as a testing ground for quantum properties of spins. Although triplons\nhave been found to play a central role in thermal and magnetic properties in\ndimerized magnets with singlet correlation, a spin angular momentum flow\ncarried by triplons, a triplon current, has not been detected yet. Here we\nreport spin Seebeck effects induced by a triplon current: triplon spin Seebeck\neffect, using a spin-Peierls system CuGeO$_3$. The result shows that the\nheating-driven triplon transport induces spin current whose sign is positive,\nopposite to the spin-wave cases in magnets. The triplon spin Seebeck effect\npersists far below the spin-Peierls transition temperature, being consistent\nwith a theoretical calculation for triplon spin Seebeck effects."
    },
    {
        "anchor": "Large spin splitting of GaN electronic states induced by Gd doping: We present a detailed study of the magnetic-field and temperature-dependent\npolarization of the near-band-gap photoluminescence in Gd-doped GaN layers. Our\nstudy reveals an extraordinarily strong influence of Gd doping on the\nelectronic states in the GaN matrix. We observe that the spin splitting of the\nvalence band reverses its sign for Gd concentrations as low as 1.6 x 10^{16}\ncm^{-3}. This remarkable result can be understood only in terms of a long range\ninduction of magnetic moments in the surrounding GaN matrix by the Gd ions.",
        "positive": "Theory of melting at high pressures: Amending Density Functional Theory\n  with Quantum Monte Carlo: We present an improved first-principles description of melting under pressure\nbased on thermodynamic integration comparing Density Functional Theory (DFT)\nand quantum Monte Carlo (QMC) treatments of the system. The method is applied\nto address the longstanding discrepancy between density functional theory (DFT)\ncalculations and diamond anvil cell (DAC) experiments on the melting curve of\nxenon, a noble gas solid where van der Waals binding is challenging for\ntraditional DFT methods. The calculations show excellent agreement with data\nbelow 20 GPa and that the high-pressure melt curve is well described by a\nLindemann behavior up to at least 80 GPa, a finding in stark contrast to DAC\ndata."
    },
    {
        "anchor": "Thermal resistance by transition between collective and non-collective\n  phonon flows in graphitic materials: Phonons in graphitic materials exhibit strong normal scattering\n(N-scattering) compared to umklapp scattering (U-scattering). The strong\nN-scattering cause collective phonon flow, unlike the relatively common cases\nwhere U-scattering is dominant. If graphitic materials have finite size and\ncontact with hot and cold reservoirs emitting phonons with non-collective\ndistribution, N-scattering change the non-collective phonon flow to the\ncollective phonon flow near the interface between graphitic material and a heat\nreservoir. We study the thermal resistance by N-scattering during the\ntransition between non-collective and collective phonon flows. Our Monte Carlo\nsolution of Peierls-Boltzmann transport equation shows that the N-scattering in\ngraphitic materials reduce heat flux from the ballistic case by around 15%,\n30%, and 40% at 100, 200, and 300 K, respectively. This is significantly larger\nthan ~ 5% reduction of Debye crystal with similar Debye temperature (~ 2300 K).\nWe associate the large reduction of heat flux by N-scattering with the\nnon-linear dispersion and multiple phonon branches with different group\nvelocities of graphitic materials.",
        "positive": "Characterisation of precipitates formed in high-pressure torsion treated\n  Mg-3.4at.%Zn alloy: Microstructural analysis of a Mg-Zn alloy deformed at room temperature by\nhigh-pressure torsion (HPT) indicates that fine-scale precipitation occurs even\nwithout post-deformation heat treatment. Small-angle X-ray scattering detects\nprecipitates with radii between 2.5-20 nm after one rotation, with little\nincrease in particle size or volume fraction after 20 rotations. High\nresolution electron micrographs identify grain boundary precipitates of\nmonoclinic Mg$_4$Zn$_7$ phase after three rotations and MgZn$_2$ after 20\nrotations."
    },
    {
        "anchor": "Role of Pressure in the Growth of Hexagonal Boron Nitride Thin Films\n  from Ammonia-Borane: We analyze the optical, chemical, and electrical properties of chemical vapor\ndeposition (CVD) grown hexagonal boron nitride (h-BN) using the precursor\nammonia-borane ($H_3N-BH_3$) as a function of $Ar/H_2$ background pressure\n($P_{TOT}$). Films grown at $P_{TOT}$ less than 2.0 Torr are uniform in\nthickness, highly crystalline, and consist solely of h-BN. At larger $P_{TOT}$,\nwith constant precursor flow, the growth rate increases, but the resulting h-BN\nis more amorphous, disordered, and $sp^3$ bonded. We attribute these changes in\nh-BN grown at high pressure to incomplete thermolysis of the $H_3N-BH_3$\nprecursor from a passivated Cu catalyst. A similar increase in h-BN growth rate\nand amorphization is observed even at low $P_{TOT}$ if the $H_3N-BH_3$ partial\npressure is initially greater than the background pressure $P_{TOT}$ at the\nbeginning of growth. h-BN growth using the $H_3N-BH_3$ precursor reproducibly\ncan give large-area, crystalline h-BN thin films, provided that the total\npressure is under 2.0 Torr and the precursor flux is well-controlled.",
        "positive": "Resistance and lifetime measurements of polymer solar cells using\n  glycerol doped poly[3,4-ethylenedioxythiophene]: poly[styrenesulfonate] hole\n  injection layers: We have performed resistivity measurements of\npoly[3,4-ethylenedioxythiophene]: poly[styrenesulfonate] (PEDOT:PSS) films with\nvarying concentrations of glycerol. Resistivity is seen to decrease\nexponentially from roughly 3 ohm-cm for pure PEDOT:PSS to 3x10-2 ohm-cm for 35\nmg/cm3 glycerol in PEDOT:PSS. Beyond this concentration adding glycerol does\nnot significantly change resistivity. Bulk heterojunction polymer solar cells\nusing these variously doped PEDOT:PSS layers as electrodes were studied to\ncharacterize the effects on efficiency and lifetime. Although our data display\nsignificant scatter, lowering the resistance of the PEDOT:PSS layers results in\nlower device resistance and higher efficiency as expected. We also note that\nthe lifetime of the devices tends to be reduced as the glycerol content of\nPEDOT:PSS is increased. Many devices show an initial increase in efficiency\nfollowed by a roughly exponential decay. This effect is explained based on\nconcomitant changes in the zero bias conductance of the samples under dark\nconditions."
    },
    {
        "anchor": "Local inhomogeneities resolved by scanning probe techniques and their\n  impact on local 2DEG formation in oxide heterostructures: Lateral inhomogeneities in the formation of 2-dimensional electron gases\n(2DEG) directly influence their electronic properties. Understanding their\norigin is an important factor for fundamental interpretations, as well as high\nquality devices. Here, we studied the local formation of the buried 2DEG at\nLaAlO3/SrTiO3 (LAO/STO) interfaces grown on STO (100) single crystals with\npartial TiO2 termination, utilizing in-situ local conductivity atomic force\nmicroscopy (LC-AFM) and scattering-type scanning near-field optical microscopy\n(s-SNOM). Using substrates with different degrees of chemical surface\ntermination, we can link the resulting interface chemistry to an inhomogeneous\n2DEG formation. In conductivity maps recorded by LC-AFM, a significant lack of\nconductivity is observed at topographic features, indicative of a local\nSrO/AlO2 interface stacking order, while significant local conductivity can be\nprobed in regions showing TiO2/LaO interface stacking order. These results\ncould be corroborated by s SNOM, showing a similar contrast distribution in the\noptical signal which can be linked to the local electronic properties of the\nmaterial. The results are further complimented by low-temperature conductivity\nmeasurements, which show an increasing residual resistance at 5 K with\nincreasing portion of insulating SrO terminated areas. Therefore, we can\ncorrelate the macroscopic electrical behavior of our samples to its nanoscopic\nstructure. Using proper parameters, 2DEG mapping can be carried out without any\nvisible alteration of sample properties, proving LC AFM and s SNOM to be viable\nand destruction-free techniques for the identification of local 2DEG formation.\nFurthermore, applying LC AFM and s SNOM in this manner opens the exciting\nprospect to link macroscopic low temperature transport to its nanoscopic\norigin.",
        "positive": "Semilocal exchange hole with an application to range-separation density\n  functional: Exchange-correlation hole is a central concept in density functional theory.\nIt not only provides justification for an exchange-correlation energy\nfunctional, but also serves as a local ingredient in nonlocal range-separation\ndensity functional. However, due to the nonlocal nature, modelig the\nconventional exact exchange hole presents a great challenge to density\nfunctional theory. In this work, we propose a semilocal exchange hole\nunderlying the Tao-Perdew-Staroverov-Scuseria (TPSS) meta-GGA functional. The\npresent model is distinct from previous models at small separation between an\nelectron and the hole around the electron. It is also different in the way it\ninterpolates between the rapidly varying iso-orbital density and the slowly\nvarying density, which is determined by the wave vector analysis based on the\nexactly solvable infinite barrier model for jellium surface. Our numerical\ntests show that the exchange hole generated from this model mimics the\nconventional exact exchange hole quite well for atoms. Finally, as a simple\napplication, we apply the hole model to construct a TPSS-based range-separation\nfunctional. Our tests show that this TPSS-based range-separation functional can\nsubstantially improve TPSS band gaps and barrier heights, without losing much\naccuracy of molecular atomization energies."
    },
    {
        "anchor": "A Light-Driven Microgel Rotor: The current understanding of motility through body shape deformation of\nmicroorganisms and the knowledge of fluid flows at the microscale provides\nample examples for mimicry and design of soft microrobots. In this work, a\ntwo-dimensional spiral is presented that is capable of rotating by\nnon-reciprocal curling deformations. The body of the microswimmer is a ribbon\nconsisting of a thermo-responsive hydrogel bilayer with embedded plasmonic gold\nnanorods. Such a system allows fast local photothermal heating and\nnon-reciprocal bending deformation of the hydrogel bilayer under\nnon-equilibrium conditions. We show that the spiral acts as a spring capable of\nlarge deformations thanks to its low stiffness, which is tunable by the\nswelling degree of the hydrogel and the temperature. Tethering the ribbon to a\nfreely rotating microsphere enables rotational motion of the spiral by\nstroboscopic irradiation. The efficiency of the rotor is estimated using\nresistive force theory for Stokes flow. The present research demonstrates\nmicroscopic locomotion by the shape change of a spiral and may find\napplications in the field of microfluidics, or soft micro-robotics.",
        "positive": "Spin-transfer in an open ferromagnetic layer: from negative damping to\n  effective temperature: Spin-transfer is a typical spintronics effect that allows a ferromagnetic\nlayer to be switched by spin-injection. Most of the experimental results about\nspin transfer are described on the basis of the Landau-Lifshitz-Gilbert\nequation of the magnetization, in which additional current-dependent damping\nfactors are added, and can be positive or negative. The origin of the damping\ncan be investigated further by performing stochastic experiments, like one shot\nrelaxation experiments under spin-injection in the activation regime of the\nmagnetization. In this regime, the N\\'eel-Brown activation law is observed\nwhich leads to the introduction of a current-dependent effective temperature.\nIn order to justify the introduction of these counterintuitive parameters\n(effective temperature and negative damping), a detailed thermokinetic analysis\nof the different sub-systems involved is performed. We propose a thermokinetic\ndescription of the different forms of energy exchanged between the electric and\nthe ferromagnetic sub-systems at a Normal/Ferromagnetic junction. The\ncorresponding Fokker Planck equations, including relaxations, are derived. The\ndamping coefficients are studied in terms of Onsager-Casimir transport\ncoefficients, with the help of the reciprocity relations. The effective\ntemperature is deduced in the activation regime."
    },
    {
        "anchor": "MICROSTRUCTURE OF Glidcop AL-60: Glidcop is an oxide-particle-dispersion strengthened copper composite that\nhas a combination of high mechanical strength and high electrical conductivity.\nIt has been used as a conductor for 100 T ultrahigh field pulsed magnets by the\nNational High Magnetic Field Laboratory, USA. In the quest for even higher\nfield pulsed magnets, material development is crucial. Since the mechanical\nproperties of a material are often determined by its micro-structure, full\ncharacterization of the microstructure of Glidcop is necessary. In this work,\nwe studied the microstructure of Glidcop AL-60 using both transmission electron\nmicroscopy (TEM) and scanning transmission electron microscopy (STEM). We\nidentified both alpha-Al2O3 and cubic eta-Al2O3 nanoparticles in AL-60 and\ninvestigated their size and density distribution. The small alumina particles\neta-Al2O3 nanoparticles with typical size of 5 to 30 nm are of triangular\nshape. They have had well defined crystal orientation relation-ship with the Cu\nmatrix. We observed dislocations pinned by the alumina nanoparticles in\ncold-drawn wires. We believed that dislocation bypassing alumina particles via\nOrowan looping was the main strengthening mechanism. We observed microcracks\nnear large particles, demonstrating the detrimental effect of large particles\nin AL-60.",
        "positive": "Stability of Oxygenated Groups on Pristine and Defective Diamond\n  Surfaces: The surface functionalization of diamond has been extensively studied through\na variety of techniques, such as oxidation. Several oxygen groups have been\ncorrespondingly detected on the oxidized diamond, such as COC (ester), CO\n(ketonic), and COH (hydroxyl). However, the composition and relative\nconcentration of these groups on diamond surfaces can be affected by the type\nof oxygenation treatment and the diamond surface quality. To investigate the\nstability of the oxygenated groups at specific diamond surfaces, we evaluated\nthrough fully atomistic reactive molecular mechanics (FARMM) simulations, using\nthe ReaxFF force field, the formation energies of CO, COC, and COH groups on\npristine and defective diamond surfaces (110), (111), and (311). According to\nour findings, the COH group has the lowest formation energy on a perfect (110)\nsurface, while the COC is favored on a defective surface. As for the (111)\nsurface, the COC group is the most stable for both pristine and defective\nsurfaces. Similarly, COC group is also the most stable one on the\ndefective/perfect (311) surface. In this way, our results suggest that if in a\ndiamond film the (110) surface is the major exposed facet, the most adsorbed\noxygen group could be either COH or COC, in which the COC would depend on the\nlevel of surface defects."
    },
    {
        "anchor": "Persistent ferromagnetism and topological phase transition at the\n  interface of a superconductor and a topological insulator: At the interface of an s-wave superconductor and a three-dimensional\ntopological insulator, Ma- jorana zero modes and Majorana helical states have\nbeen proposed to exist respectively around magnetic vortices and geometrical\nedges. Here we first show that a single magnetic impurity at such an interface\nsplits each resonance state of a given spin channel outside the superconducting\ngap, and also induces two new symmetric impurity states inside the gap. Next we\nfind that an increase in the superconducting gap suppresses both the\noscillation magnitude and period of the RKKY inter- action between two\ninterface magnetic impurities mediated by BCS quasi-particles. Within a mean\nfield approximation, the ferromagnetic Curie temperature is found to be\nessentially independent of the superconducting gap, an intriguing phenomenon\ndue to a compensation effect between the short-range ferromagnetic and\nlong-range anti-ferromagnetic interactions. The existence of persis- tent\nferromagnetism at the interface allows realization of a novel topological phase\ntransition from a non-chiral to a chiral superconducting state at sufficiently\nlow temperatures, providing a new platform for topological quantum computation.",
        "positive": "Theory of momentum-resolved magnon electron energy loss spectra: The\n  case of Yttrium Iron Garnet: We explore the inelastic spectra of electrons impinging in a magnetic system.\nThe methodology here presented is intended to highlight the charge-dependent\ninteraction of the electron beam in a STEM-EELS experiment, and the local\nvector potential generated by the magnetic lattice. This interaction shows an\nintensity $10^{-2}$ smaller than the purely spin interaction, which is taken to\nbe functionally the same as in the inelastic neutron experiment. On the other\nhand, it shows a strong scattering vector dependence ($\\kappa^{-4}$) and a\ndependence with the relative orientation between the probe wavevector and the\nlocal magnetic moments of the solid. We present YIG as a case study due to its\nhigh interest by the community."
    },
    {
        "anchor": "Modeling of High Composition AlGaN Channel HEMTs with Large Threshold\n  Voltage: We report on the potential of high electron mobility transistors (HEMTs)\nconsisting of high composition AlGaN channel and barrier layers for power\nswitching applications. Detailed 2D simulations show that threshold voltages in\nexcess of 3 V can be achieved through the use of AlGaN channel layers. We also\ncalculate the two-dimensional electron gas (2DEG) mobility in AlGaN channel\nHEMTs and evaluate their power figures of merit as a function of device\noperating temperature and Al mole fraction in the channel. Our models show that\npower switching transistors with AlGaN channels would have comparable\non-resistance to GaN-channel based transistors for the same operation voltage.\nThe modeling in this paper shows the potential of high composition AlGaN as a\nchannel material for future high threshold enhancement mode transistors.",
        "positive": "Machine learning for predictive condensed-phase simulation: We show how machine learning techniques based on Bayesian inference can be\nused to reach new levels of realism in the computer simulation of molecular\nmaterials, focusing here on water. We train our machine-learning algorithm\nusing accurate, correlated quantum chemistry, and predict energies and forces\nin molecular aggregates ranging from clusters to solid and liquid phases. The\nwidely used electronic-structure methods based on density-functional theory\n(DFT) give poor accuracy for molecular materials like water, and we show how\nour techniques can be used to generate systematically improvable corrections to\nDFT. The resulting corrected DFT scheme gives remarkably accurate predictions\nfor the relative energies of small water clusters and of different ice\nstructures, and greatly improves the description of the structure and dynamics\nof liquid water."
    },
    {
        "anchor": "Fingerprints of energy dissipation for exothermic surface chemical\n  reactions: O$_2$ on Pd(100): We present first-principles calculations of the sticking coefficient of O$_2$\nat Pd(100) to assess the effect of phononic energy dissipation on this kinetic\nparameter. For this we augment dynamical simulations on six-dimensional\npotential energy surfaces (PESs) representing the molecular degrees of freedom\nwith various effective accounts of surface mobility. In comparison to the\nprevalent frozen-surface approach energy dissipation is found to qualitatively\naffect the calculated sticking curves. At the level of a generalized Langevin\noscillator (GLO) model we achieve good agreement with experimental data. The\nagreement is similarly reached for PESs based on two different semi-local\ndensity-functional theory functionals. This robustness of the simulated\nsticking curve does not extend to the underlying adsorption mechanism, which is\npredominantly directly dissociative for one functional or molecularly trapped\nfor the other. Completely different adsorption mechanisms therewith lead to\nrather similar sticking curves that agree equally well with the experimental\ndata. This highlights the danger of the prevalent practice to extract\ncorresponding mechanistic details from simple fingerprints of measured sticking\ndata for such exothermic surface reactions.",
        "positive": "Effect of Triangular Pre-Cracks on the Mechanical Behavior of 2D\n  MoTe$_2$: A Molecular Dynamics Study: Among two-dimensional (2D) materials, transition metal dichalcogenides (TMDs)\nstand out for their remarkable electronic, optical, and chemical properties. In\naddition to being variable bandgap semiconductor materials, the atomic thinness\nprovides flexibility to TMDs. Therefore, understanding the physical properties\nof TMDs for applications in flexible and wearable devices is crucial. Despite\nthe growing enthusiasm surrounding two-dimensional transition metal\ndichalcogenides (TMDs), our understanding of the mechanical characteristics of\nmolybdenum ditelluride (MoTe$_2$) remains limited. The mechanical properties of\nMoTe$_2$ deteriorate in the presence of pre-existing cracks or vacancy defects,\nwhich are very common in grown TMDs. In this study, the fracture properties and\ncrack propagation of monolayer molybdenum ditelluride (MoTe$_2$) sheets\ncontaining pre-existing triangular cracks with various vertex angles are\ninvestigated by performing molecular dynamics (MD) simulations of uniaxial and\nbiaxial tensile loading. Due to pre-crack length, angle, and perimeter\nvariations, monolayer MoTe$_2$ with pre-existing cracks underwent considerable\nchanges in Young's modulus, tensile strength, fracture toughness, and fracture\nstrain values. We have found that the pre-cracked MoTe$_2$ is more brittle than\nits pristine counterpart. Regulated alteration of pre-crack angle under\nconstant simulation conditions improved the uniaxial mechanical properties.\nSimilarly, regulated alteration of the perimeter of the pre-crack resulted in\nimproved biaxial mechanical properties. This study contributes to the\nfoundational knowledge for advanced design strategies involving strain\nengineering in MoTe$_2$ and other similar transition metal dichalcogenides."
    },
    {
        "anchor": "Two-dimensional spinodal interface in one-step grown graphene-molybdenum\n  carbide heterostructures: Heterostructures made by stacking different materials on top of each other\nare expected to exhibit unusual properties and new phenomena. Interface of the\nheterostructures plays a vital role in determining their properties. Here, we\nreport the observation of a two-dimensional (2D) spinodal interface in\ngraphene-molybdenum carbide ({\\alpha}-Mo2C) heterostructures, which arises from\nspinodal decomposition occurring at the heterointerface, by using scanning\ntunneling microscopy. Our experiment demonstrates that the 2D spinodal\ninterface modulates graphene into whispering gallery resonant networks filled\nwith quasi-bound states of massless Dirac fermions. Moreover, below the\nsuperconducting transition temperature of the underlying {\\alpha}-Mo2C, the 2D\nspinodal interface behaves as disorders, resulting in the breakdown of the\nproximity-induced superconductivity in graphene. Our result sheds new light on\ntuning properties of heterostructures based on interface engineering.",
        "positive": "Tuning Coherent-Phonon Heat Transport in LaCoO$_3$/SrTiO$_3$\n  Superlattices: Accessing the regime of coherent phonon propagation in nanostructures opens\nenormous possibilities to control the thermal conductivity in energy harvesting\ndevices, phononic circuits, etc. In this paper we show that coherent phonons\ncontribute substantially to the thermal conductivity of LaCoO3/SrTiO3 oxide\nsuperlattices, up to room temperature. We show that their contribution can be\ntuned through small variations of the superlattice periodicity, without\nchanging the total superlattice thickness. Using this strategy, we tuned the\nthermal conductivity by 20% at room temperature. We also discuss the role of\ninterface mixing and epitaxial relaxation as an extrinsic, material dependent\nkey parameter for understanding the thermal conductivity of oxide\nsuperlattices."
    },
    {
        "anchor": "Density Functional Theory Study of Light Metal (Li/Na/Ca) Functionalized\n  Borophosphene for Reversible Hydrogen Storage: Borophosphene is investigated for hydrogen storage by density functional\ntheory calculations through Li, Na and Ca decoration. Decoration enhances the\nbinding energy from -0.047 eV/H2 to -0.20 -- -0.42 eV/H2. PDOS and Bader charge\nanalysis elucidate the role of adatom decoration in charge transfer and better\nbinding. Up to 10, 12 and 20 H2 molecules can be adsorbed over a single Li, Na\nand Ca adatom, respectively, in a supercell of 32 atoms. Desorption temperature\nis calculated from the binding energies. A complete discharge of the stored\nmolecules from decorated borophosphene can be realized in temperature range of\n125 to 531 K. Further, decoration at multiple sites of the substrate is\nperformed to evaluate the theoretical gravimetric density. With Li, Na, and Ca\noverloading, gravimetric densities of 6.22%, 5.34%, and 6.08% are obtained. NEB\nresults show that inter-site energy barriers of the adatoms are larger than\ntheir thermal energy by an order.",
        "positive": "Electronic structure and magnetism in slightly doped SrB_6: Spin-polarized band calculations for supercells of SrB$_{6}$, where a La-,\nIn- or Al- impurity or a vacancy is replacing one Sr, are performed within the\nlocal spin density approximation. Moderately large cells with 8 formula units\n(56 atoms) are studied for all dopings and large ones with 27 formula units\n(189 atoms) for the case of La-doping. The undoped system has a vanishing\ndensity-of-states (DOS) at the Fermi energy (E$_F$), while the additional La-d\nband makes E$_F$ to enter the bands above the gap. An Al (or In) impurity has\nthe opposite effect, with a rigid-band like shift of E_F to below the gap. In\nthe former case, the addition of a d-electron makes a local, impurity-like\nmodification of the electronic structure close to the La atom. As has been\nshown in a previous publication, it can lead to a weak ferromagnetic state.\nThis result is shown to persist at even lower doping, by the 189-atom cell\ncalculations, with a moment of the order 0.1 $\\mu_B$ per La impurity. An\naddition of a p-electron, by an In-impurity, makes no similar effect. The\nmagnetic state can be understood from a charge transfer and an additional gain\nin potential energy, as a spin-splitting is imposed. Different models with\nmodified localization of the La-band are made in order to show the correlation\nbetween charge transfer and the size of the magnetic moment."
    },
    {
        "anchor": "Ab initio based analysis of grain boundary segregation in Al-Mg and\n  Al-Zn binary alloys: Based on ab-initio simulations, we report on the nature of principally\ndifferent mechanisms for interaction of Mg and Zn atoms with grain boundaries\nin Al alloys leading to different morphology of segregation. The Mg atoms\nsegregate in relatively wide GB region with heterogeneous agglomerations due to\nthe deformation mechanism of solute-GB interaction. In contrast, in the case of\nZn atoms an electronic mechanism associated with the formation of directional\nbonding is dominating in the solute-GB interaction. As a result, for Zn atoms\nit is energetically beneficial to occupy interstitial positions at the very GB\nand to be arranged into thin layers along the GBs. The results obtained show\nthe essential role of elements chemistry in segregation formation and explain\nthe qualitative features in morphology of GB segregation observed in Al-Mg and\nAl-Zn alloys with ultrafine grains.",
        "positive": "Lattice Properties of PbX (X = S, Se, Te): Experimental Studies and ab\n  initio Calculations Including Spin-Orbit Effects: During the past five years the low temperature heat capacity of simple\nsemiconductors and insulators has received renewed attention. Of particular\ninterest has been its dependence on isotopic masses and the effect of spin-\norbit coupling in ab initio calculations. Here we concentrate on the lead\nchalcogenides PbS, PbSe and PbTe. These materials, with rock salt structure,\nhave different natural isotopes for both cations and anions, a fact that allows\na systematic experimental and theoretical study of isotopic effects e.g. on the\nspecific heat. Also, the large spin-orbit splitting of the 6p electrons of Pb\nand the 5p of Te allows, using a computer code which includes spin-orbit\ninteraction, an investigation of the effect of this interaction on the phonon\ndispersion relations and the temperature dependence of the specific heat and on\nthe lattice parameter. It is shown that agreement between measurements and\ncalculations significantly improves when spin-orbit interaction is included."
    },
    {
        "anchor": "Water splits to degrade two-dimensional group-IV monochalcogenides in\n  nanoseconds: The experimental exfoliation of layered group-IV monochalcogenides\n--semiconductors isostructural to black phosphorus-- using processes similar to\nthose followed in the production of graphene or phosphorene has turned out\nunsuccessful thus far, as if the chemical degradation observed in black\nphosphorus was aggravated in these monochalcogenides. Here, we document a\nfacile dissociation of water by these materials within ten nanoseconds from\nroom-temperature Car-Parrinello molecular dynamics calculations under standard\ntemperature and pressure conditions. These results suggest that humidity must\nbe fully eradicated to exfoliate monolayers successfully, for instance, by\nplacing samples in a hydrophobic solution during mechanical exfoliation. From\nanother materials perspective, these two-dimensional materials that create\nindividual hydrogen ions out of water without illumination may become relevant\nfor applications in hydrogen production and storage.",
        "positive": "In-plane magnetic structure and exchange interactions in the\n  high-temperature antiferromagnet Cr2Al: The ordered tetragonal intermetallic Cr$_2$Al forms the same structure type\nas Mn$_2$Au, and the latter has been heavily investigated for its potential in\nantiferromagnetic spintronics due to its degenerate in-plane N\\'{e}el vector.\nWe present the single crystal flux growth of Cr$_2$Al and orientation-dependent\nmagnetic properties. Powder neutron diffraction of Cr$_2$Al and\nfirst-principles simulations reveal that the magnetic ordering is likely\nin-plane and therefore identical to Mn$_2$Au, providing a second material\ncandidate in the MoSi$_2$ structure type to evaluate the fundamental\ninteractions that govern spintronic effects. The single ordering transition\nseen in thermal analysis and resistivity indicates that no canting of the\nmoments along the $c$ axis is likely. Magnetometry, resistivity, and\ndifferential scanning calorimetry measurements confirm the N\\'{e}el temperature\nto be $634 \\pm 2$ K. First-principles simulations indicate that the system has\na small density of states at the Fermi energy and confirm the lowest-energy\nmagnetic ground state ordering, while Monte Carlo simulations match the\nexperimental N\\'{e}el temperature."
    },
    {
        "anchor": "Performance of dopamine modified 0.5(Ba0.7Ca0.3)TiO3-0.5Ba(Zr0.2Ti0.8)O3\n  filler in PVDF nanocomposite as flexible energy storage and harvester: We demonstrate the potential of dopamine modified\n0.5(Ba0.7Ca0.3)TiO3-0.5Ba(Zr0.2Ti0.8)O3 filler incorporated poly-vinylidene\nfluoride (PVDF) composite prepared by solution cast method as both flexible\nenergy storage and harvesting devices. The introduction of dopamine in filler\nsurface functionalization acts as bridging elements between filler and polymer\nmatrix and results in a better filler dispersion and an improved dielectric\nloss tangent (<0.02) along with dielectric permittivity ranges from 9 to 34\nwhich is favorable for both energy harvesting and storage. Additionally, a\nsignificantly low DC conductivity (< 10-9 ohm-1cm-1) for all composites was\nachieved leading to an improved breakdown strength and charge accumulation\ncapability. Maximum breakdown strength of 134 KV/mm and corresponding energy\nstorage density 0.72 J/cm3 were obtained from the filler content 10 weight%.\nThe improved energy harvesting performance was characterized by obtaining a\nmaximum piezoelectric charge constant (d33) = 78 pC/N, and output voltage\n(Vout) = 0.84 V along with maximum power density of 3.46 microW/cm3 for the\nfiller content of 10 wt%. Thus, the results show\n0.5(Ba0.7Ca0.3)TiO3-0.5Ba(Zr0.2Ti0.8)O3/PVDF composite has the potential for\nenergy storage and harvesting applications simultaneously that can\nsignificantly suppress the excess energy loss arises while utilizing different\nmaterial.",
        "positive": "Stiffening of nanoporous Au as a result of dislocation density increase\n  upon characteristic length reduction: Structure is the most distinctive feature of nanoporous metals. The intricate\nmaze of rounded shapes, where ligaments and pores run after each other\ndisorderly, strikes imagination no less than it imparts properties that, tuned\nby size effects, have no counterpart in the bulk form. Indisputably, nanoporous\nAu has been the absolute protagonist of the field of study, unveiling the\ndisrupting potential of nanoporous metals in areas ranging from catalysis to\nenergy and sensing. Here, we still focus on nanoporous Au, addressing the\nlong-standing issue of mechanical properties in nanoporous metals. In\nparticular, we investigate how Young's modulus changes with ligament size,\nbeing the porosity the same. Based on atomistic replicas generated starting\nfrom experimental tomographic evidence, atomistic simulations reveal that\nnanoporous Au stiffens as ligaments become finer, reproducing experimental\nfindings obtained by nanoindentation of dealloyed samples. Ruled out surface\nstress effects, theoretical considerations relate stiffening to the dislocation\ndensity increase."
    },
    {
        "anchor": "Intrinsic avalanches and collective phenomena in a Mn(II)-free radical\n  ferrimagnetic chain: Magnetic hysteresis loops below 300 mK on single crystals of the Mn(II) -\nnitronyl nitroxide free radical chain (Mn(hfac)_2({\\it R})-3MLNN) present\nabrupt reversals of the magnetization, or avalanches. We show that, below 200\nmK, the avalanches occur at a constant field, independent of the sample and so\npropose that this avalanche field is an intrinsic property. We compare this\nfield to the energy barrier existing in the sample and conclude that the\navalanches are provoked by multiple nucleation of domain-walls along the\nchains. The different avalanche field observed in the zero field cooled\nmagnetization curves suggests that the avalanche mechanisms are related to the\ncompetition between ferromagnetic and antiferromagnetic order in this compound.",
        "positive": "Electron Transport in MoWSeS Monolayers in Presence of an External\n  Electric Field: The influence of an external electric field on single-layer transition-metal\ndichalcogenides TX2 with T = Mo, W and X = S, Se (MoWSeS) have been\ninvestigated by means of density-functional theory within two-dimensional\nperiodic boundary conditions under consideration of relativistic effects\nincluding the spin-orbit interactions. Our results show that the external field\nmodifies the band structure of the monolayers, in particular the conduction\nband. This modification has, however, very little influence on the band gap and\neffective masses of holes and electrons at the K point, and also the spin-orbit\nsplitting of these monolayers is almost unaffected. Our results indicate a\nremarkable stability of the electronic properties of TX2 monolayers with\nrespect to gate voltages. A reduction of the electronic band gap is observed\nonly starting from field strengths of 2.0 V per {\\AA} (3.5 V per {\\AA}) for\nselenides (sulphides), and the transition to a metallic phase would occur at\nfields of 4.5 V per {\\AA} (6.5 V per {\\AA})."
    },
    {
        "anchor": "Magnetic anisotropy of single 3d spins on CuN surface: First-principles calculations of the magnetic anisotropy energy for Mn- and\nFe-atoms on CuN/Cu(001) surface are performed making use of the torque method.\nThe easy magnetization direction is found to be different for Mn and Fe atoms\nin accord with the experiment. It is shown the magnetic anisotropy has a\nsingle-ion character and mainly originates from the local magnetic moment of\nMn- and Fe-atoms. The uniaxial magnetic anisotropy constants are calculated in\nreasonable agreement with the experiment.",
        "positive": "High-yield production of quantum corrals in a surface reconstruction\n  pattern: The power of surface chemistry to create atomically precise nanoarchitectures\noffers intriguing opportunities to advance the field of quantum technology.\nStrategies for building artificial electronic lattices by individually\npositioning atoms or molecules result in precisely tailored structures but lack\nstructural robustness. Here, taking the advantage of strong bonding of Br atoms\non noble metal surfaces, we report the production of stable quantum corrals by\ndehalogenation of hexabromobenzene molecules on a preheated Au(111) surface.\nThe byproducts, Br adatoms, are confined within a new surface reconstruction\npattern and aggregate into nanopores with an average size of 3.7+-0.1 nm, which\ncreate atomic orbital-like quantum resonance states inside each corral due to\nthe interference of scattered electron waves. Remarkably, the atomic orbitals\ncan be hybridized into molecular-like orbitals with distinct bonding and\nanti-bonding states. Our study opens up an avenue to fabricate quantum\nstructures with high yield and superior robustness."
    },
    {
        "anchor": "The role of stoichiometric vacancy periodicity in pressure-induced\n  amorphization of the Ga2SeTe2 semiconductor alloy: We observe that pressure-induced amorphization of Ga2SeTe2 (a III-VI\nsemiconductor) is directly influenced by the periodicity of its intrinsic\ndefect structures. Specimens with periodic and semi-periodic two-dimensional\nvacancy structures become amorphous around 10-11 GPa in contrast to those with\naperiodic structures, which amorphize around 7-8 GPa. The result is a notable\ninstance of altering material phase-change properties via rearrangement of\nstoichiometric vacancies as opposed to adjusting their concentrations. Based on\nour experimental findings, we posit that periodic two-dimensional vacancy\nstructures in Ga2SeTe2 provide an energetically preferred crystal lattice that\nis less prone to collapse under applied pressure. This is corroborated through\nfirst-principles electronic structure calculations, which demonstrate that the\nenergy stability of III-VI structures under hydrostatic pressure is highly\ndependent on the configuration of intrinsic vacancies.",
        "positive": "Tunable positions of Weyl nodes via magnetism and pressure in the\n  ferromagnetic Weyl semimetal CeAlSi: The noncentrosymmetric ferromagnetic Weyl semimetal CeAlSi with simultaneous\nspace-inversion (SI) and time-reversal (TR) symmetry breaking provides a unique\nplatform for the exploration of novel topological states. Here, by employing\nelectrical and thermoelectrical transport, angle-resolved photoemission\nspectroscopy (ARPES), high-pressure techniques, and band calculations, we\ndemonstrate that magnetism and pressure can serve as efficient parameters to\ntune the positions of Weyl nodes in CeAlSi. At ambient pressure, an anomalous\nHall effect (AHE) and an anomalous Nernst effect (ANE) arise in the\nparamagnetic state, and then are enhanced when temperature approaches the\nferromagnetic ordering temperature, evidencing magnetism facilitates the\nAHE/ANE. Such an enhancement of AHE/ANE can be ascribed to the tuning of the\npositions of Weyl nodes via magnetism. The ARPES measurements reveal that the\nferromagnetism serves as a pivotal knob to tune the band structure of CeAlSi\nboth in the bulk and on the surface. Such magnetism-tunable electronic\nstructure has hitherto not been reported in other magnetic $R$Al$Pn$ ($R$ =\nrare earth elements, $Pn$ = Si, Ge) siblings, suggesting the great potential of\ncontrolling Weyl node positions in CeAlSi. Under pressure, an enhancement and a\nsign change of AHE are discovered. Based on band calculations, the evolution of\nAHE may root in the tuning of Weyl nodes via pressure. Moreover, multiple\npressure-induced phase transitions are uncovered. These findings indicate that\nCeAlSi provides a unique and tunable platform for exploring exotic topological\nphysics and electron correlations, as well as catering to an array of potential\napplications, such as spintronics and thermoelectrics."
    },
    {
        "anchor": "Tunnel barrier enhanced voltage signals generated by magnetization\n  precession of a single ferromagnetic layer: We report the electrical detection of magnetization dynamics in an\nAl/AlOx/Ni80Fe20/Cu tunnel junction, where a Ni80Fe20 ferromagnetic layer is\nbrought into precession under the ferromagnetic resonance (FMR) conditions. The\ndc voltage generated across the junction by the precessing ferromagnet is\nenhanced about an order of magnitude compared to the voltage signal observed\nwhen the contacts in this type of multilayered structure are ohmic. We discuss\nthe relation of this phenomenon to magnetic spin pumping and speculate on other\npossible underlying mechanisms responsible for the enhanced electrical signal.",
        "positive": "Probing relativistic electrons in the Weyl semimetal NbP using\n  transverse electron focusing: Weyl semimetals (WSMs) are topological semimetals characterized by\nexceptional transport properties, including extremely high mobility,\nmagnetoresistance, and electrical conductivity, all of which hold great promise\nfor technological applications. However, the connection between the extreme\ntransport properties of WSMs to the distinctive features of the Weyl Fermi\nsurface, characterized by relativistic, chiral bulk states and topological\nsurface states, remains experimentally unexplored. To gain deeper insights into\nthe properties of Weyl fermions and their contribution to transport, we employ\na combined approach of transverse electron focusing (TEF) and Shubnikov de Haas\n(SdH) experiments conducted on microstructured single-crystals of the WSM\nniobium phosphide (NbP). TEF and SdH generate distinct signals for charged\nquasiparticles with different momenta and Fermi surface areas, respectively,\nthereby enabling focused study on Weyl fermions in a material like NbP, where\nseveral types of carriers, both topological and not, contribute to transport\nsimultaneously. The combination of TEF and SdH allows measuring Weyl Fermi\nsurface characteristics with a sensitivity beyond angle-resolved photoemission\nspectroscopy. Moreover, carriers' density, type, mass, and mobility can be\nextracted, giving valuable insights into Weyl fermions transport properties.\nOur findings support that the extreme mobility of NbP originates from bulk,\nachiral, and relativistic electrons."
    },
    {
        "anchor": "Synthesis, Infra-red, Raman, NMR and structural characterization by\n  X-ray Diffraction of [C12H17N2]2CdCl4 and [C6H10N2]2Cd3Cl10 compounds: The synthesis, infra-red, Raman and NMR spectra and crystal structure of 2,\n4, 4- trimethyl-4, 5- dihydro-3H-benzo[b] [1, 4] diazepin-1-ium\ntetrachlorocadmate, [C12H17N2]2CdCl4 and benzene-1,2-diaminium\ndecachlorotricadmate(II) [C6H10N2]2Cd3Cl10 are reported.\n  The [C12H17N2]2CdCl4 compound crystallizes in the triclinic system (P-1 space\ngroup) with Z = 2 and the following unit cell dimensions: a = 9.6653(8)\nangstrom, b = 9.9081(9) angstrom, c = 15.3737(2) angstrom, alpha =\n79.486(1)degrees, beta = 88.610(8)degrees and gamma = 77.550(7)degrees. The\nstructure was solved by using 4439 independent reflections down to R value of\n0.029. In crystal structure, the tetrachlorocadmiate anion is connected to two\norganic cations through N-H...Cl hydrogen bonds and Van Der Waals interaction\nas to build cation-anion-cation cohesion. The [C6H10N2]2Cd3Cl10 crystallizes in\nthe triclinic system (P-1 space group). The unit cell dimensions are a = 6.826\n(5)angstrom, b = 9.861 (7)angstrom, c = 10.344 (3)angstrom, alpha = 103.50\n(1)degrees, beta = 96.34 (4)degrees and gamma = 109.45 (3)degrees, Z=2. The\nfinal R value is 0.053 (Rw=0.128). Its crystal structure consists of organic\ncations and polymeric chains of [Cd3Cl10]4- anions running along the [011]\ndirection, In The [C6H10N2]2Cd3Cl10 compounds hydrogen bond interactions\nbetween the inorganic chains and the organic cations, contribute to the crystal\npacking.\n  PACS Codes: 61.10.Nz, 61.18.Fs, 78.30.-j",
        "positive": "Double glass transition in polyethylene naphthalate structural\n  relaxation by MDSC, BDS and TSDC: We present the experimental study of the primary, $\\alpha$, and secondary,\n$\\beta^*$, relaxations of the glassy polymer polyethylene naphthalate (PEN), by\nModulated Differential Scanning Calorimetry (MDSC), Thermally Stimulated\nDischarge Currents (TSDC) and Broadband Dielectric Spectroscopy (BDS). Results\nshow how the $\\alpha$ and $\\beta^*$ relaxations can be considered part of a\nvery broad and distributed relaxation. The $\\beta^*$ relaxation is composed of\na main contribution ($\\beta_3^*$) and two additional ones ($\\beta_1^*$ and\n$\\beta_2^*$) and each elementary mode of the relaxation has its own glass\ntransition temperature. This scenario gives rise to an extended glass\ntransition mainly centered in $T_{g\\beta^*} \\sim 305$ K and $T_{g\\alpha} \\sim\n387$ K."
    },
    {
        "anchor": "Common universal behaviors of magnetic domain walls driven by\n  spin-polarized electrical current and magnetic field: We explore universal behaviors of magnetic domain wall driven by the\nspin-transfer of an electrical current, in a ferromagnetic (Ga,Mn)(As,P) thin\nfilm with perpendicular magnetic anisotropy. For a current direction transverse\nto domain wall, the dynamics of the thermally activated creep regime and the\ndepinning transition are found to be compatible with a self-consistent\nuniversal description of magnetic field induced domain wall dynamics. This\ncommon universal behavior, characteristic of the so-called quenched\nEdwards-Wilkinson universality class, is confirmed by a complementary and\nindependent analysis of domain wall roughness. However, the tilting of domain\nwalls and the formation of facets is produced by the directionality of\ninteraction with the current, which acts as a magnetic field only in the\ndirection transverse to domain wall.",
        "positive": "Atomic adsorption on pristine graphene along the Periodic Table of\n  Elements - From PBE to non-local functionals: The understanding of atomic adsorption on graphene is of high importance for\nmany advanced technologies. Here we present a complete database of the atomic\nadsorption energies for the elements of the Periodic Table up to the atomic\nnumber 86 (excluding lanthanides) on pristine graphene. The energies have been\ncalculated using the projector augmented wave (PAW) method with PBE, long-range\ndispersion interaction corrected PBE (PBE+D2, PBE+D3) as well as non-local\nvdW-DF2 approach. The inclusion of dispersion interactions leads to an\nexothermic adsorption for all the investigated elements. Dispersion\ninteractions are found to be of particular importance for the adsorption of low\natomic weight earth alkaline metals, coinage and s-metals (11th and 12th\ngroups), high atomic weight p-elements and noble gases. We discuss the observed\nadsorption trends along the groups and rows of the Periodic Table as well some\ncomputational aspects of modelling atomic adsorption on graphene."
    },
    {
        "anchor": "Structure prediction based on ab initio simulated annealing for boron\n  nitride: Possible crystalline modifications of chemical compounds at low temperatures\ncorrespond to local minima of the energy landscape. Determining these minima\nvia simulated annealing is one method for the prediction of crystal structures,\nwhere the number of atoms per unit cell is the only information used. It is\ndemonstrated that this method can be applied to covalent systems, at the\nexample of boron nitride, using ab initio energies in all stages of the\noptimization, i.e. both during the global search and the subsequent local\noptimization. Ten low lying structure candidates are presented, including both\nlayered structures and 3d-network structures such as the wurtzite and zinc\nblende types, as well as a structure corresponding to the beta-BeO type.",
        "positive": "Determination of magnetic form factors for organic charge transfer\n  salts: a first principles investigation: Organic charge transfer salts show a variety of complex phases ranging from\nantiferromagnetic long-range order, spin liquid, bad metal or even\nsuperconductivity. A powerful method to investigate magnetism is spin-polarized\ninelastic neutron scattering. However, such measurements have often been\nhindered in the past by the small size of available crystals as well as by the\nfact that the spin in these materials is distributed over molecular rather than\natomic orbitals and good estimates for the magnetic form factors are missing.\nBy considering Wannier functions obtained from density functional theory\ncalculations, we derive magnetic form factors for a number of representative\norganic molecules. Compared to Cu2+, the form factors |F(q)|2 fall off more\nrapidly as function of q reflecting the fact that the spin density is very\nextended in real space. Form factors |F(q)|2 for TMTTF, BEDT-TTF and\n(BEDT-TTF)2 have anisotropic and nonmonotonic structure."
    },
    {
        "anchor": "Selective coupling of coherent optical phonons in\n  YBa$_2$Cu$_3$O$_{7-\u03b4}$ with electronic transitions: We investigate coherent lattice dynamics in optimally doped\nYBa$_2$Cu$_3$O$_{7-\\delta}$ driven by ultrashort ($\\sim$ 12 fs) near infrared\n(NIR) and near ultraviolet (NUV) pulses. Transient reflectivity experiments,\nperformed at room temperature and under moderate ($<$0.1 mJ/cm$^2$) excitation\nfluence, reveal $A_g$-symmetry phonon modes related to the O(2,3) bending in\nthe CuO$_2$ planes and to the apical O(4) stretching at frequencies between 10\nand 15 THz, in addition to the previously reported Ba and Cu(2) vibrations at\n3.5 and 4.5 THz. The relative coherent phonon amplitudes are in stark contrast\nto the relative phonon intensities in the spontaneous Raman scattering spectrum\nexcited at the same wavelength. This contrast indicates mode-dependent\ncontributions of the Raman and non-Raman mechanisms to the coherent phonon\ngeneration. We show that the particularly intense coherent Cu(2) phonon,\ntogether with its initial phase, supports its generation predominately via a\ndisplacive mechanism, possibly involving the charge transfer within the CuO$_2$\nplanes. The small amplitude of the coherent out-of-phase O(2,3) bending mode at\n10 THz also suggests the involvement of non-Raman generation mechanism. The\ngeneration of the other coherent phonons can in principle be explained within\nthe framework of Raman mechanism. When the pump light has the polarization\ncomponent perpendicular to the CuO$_2$ plane, the coherent O(4) mode at 15 THz\nis strongly enhanced compared to the in-plane excitation, corresponding to the\nlarge polarizability component associated with the hopping between the apical\nand the chain oxygens, O(4) and O(1).",
        "positive": "Large scale chemical functionalization of graphene with nanometer\n  resolution: Anchoring various functional groups to graphene is the most versatile\napproach for tailoring its functional properties. To date, one must use a\nspecial tunneling microscope for attaching a molecule at a specific position on\nthe graphene with resolution better than several hundred nanometers, however,\nachieving this resolution is impossible on a large scale. We demonstrate for\nthe first time that chemical functionalization can be achieved with nanometer\nresolution by introducing strain with nanometer scale modulation into a\ngraphene layer. The spatial distribution of the strain has been achieved by\ntransferring a single-layer graphene (SLG) onto a substrate decorated by a few\nnm large nanoparticles (NPs). By changing the number of NPs on the substrate,\nthe amount of locally strained SLG increases, as confirmed by atomic force\nmicroscopy (AFM) and Raman spectroscopy investigations. We further carried out\nhydrogenation and fluorination on the SLG with increasing amount of nanoscale\ncorrugations. Raman spectroscopy, AFM and X-ray photoelectron spectroscopy\nrevealed unambiguously that the level of functionalization increases\nproportionally with the number of NPs, which means an increasing number of the\nlocally strained SLG. Our approach thus enables control of the amount and the\nposition of functional groups on graphene with nanometer resolution."
    },
    {
        "anchor": "Magnetotransport properties of Cd3As2 nanostructures: Three-dimensional (3D) topological Dirac semimetal is a new kind of material\nthat has a linear energy dispersion in 3D momentum space and can be viewed as\nan analog of graphene. Extensive efforts have been devoted to the understanding\nof bulk materials, but yet it remains a challenge to explore the intriguing\nphysics in low-dimensional Dirac semimetals. Here, we report on the synthesis\nof Cd3As2 nanowires and nanobelts and a systematic investigation of their\nmagnetotransport properties. Temperature-dependent ambipolar behavior is\nevidently demonstrated, suggesting the presence of finite-size of bandgap in\nnanowires. Cd3As2 nanobelts, however, exhibit metallic characteristics with a\nhigh carrier mobility exceeding 32,000 cm2V-1s-1 and pronounced anomalous\ndouble-period Shubnikov-de Haas (SdH) oscillations. Unlike the bulk\ncounterpart, the Cd3As2 nanobelts reveal the possibility of unusual change of\nthe Fermi sphere owing to the suppression of the dimensionality. More\nimportantly, their SdH oscillations can be effectively tuned by the gate\nvoltage. The successful synthesis of Cd3As2 nanostructures and their rich\nphysics open up exciting nanoelectronic applications of 3D Dirac semimetals.",
        "positive": "Theory of water desalination by porous electrodes with fixed chemical\n  charge: Water desalination by capacitive deionization (CDI) is performed via\nelectrochemical cells consisting of two porous carbon electrodes. Upon\ntransferring charge from one electrode to the other, ions are removed from the\nfeedwater by electrosorption into electrical double layers (EDLs) within the\nmicropores of the porous carbon. When using electrodes containing fixed\nchemical charge in the micropores, various counterintuitive observations have\nbeen made, such as \"inverted CDI\" where upon charging, ions are released from\nthe electrode, and the feedwater is only desalinated when the cell is\ndischarging. We set up an EDL model including chemical charge that explains\nthese observations and makes predictions for a working range of enhanced\ndesalination by CDI."
    },
    {
        "anchor": "The Evolution of Alq3 Films Exposure to Air: Small molecular solar cell becomes more stable when a thin\ntris-(8-hydroxyquinoline) aluminum (Alq3) buffer layer instead of bathocuproine\n(BCP) is inserted between the active layer and electrode. In this work, we\nintroduce a single layer device (ITO / Alq3 / Au) exposure to air to\ninvestigate the role of Alq3 in organic solar cells. The large PL intensity and\nundetectable Raman peaks of 8-hydroxyquinoline (8-Hq), a degradation product of\nAlq3 through chemical reaction, indicate that the degradation of Alq3 is not\nsevere even after a few hundred hours exposure. Thus the Alq3 buffer layer\ngives a good protection of the active layers against oxygen\\water permeation\ncomparing with BCP. However, the small quantity of degraded Alq3 products can\nenhance the current density (after 15 h) in single layer Alq3 device, which is\nreflected in the decrease of parallel resistance Rp. Therefore, due to the\nenhanced charge transport and the long term better protection from ambient\noxygen/water, the lifetime of small molecular solar cell with Alq3 buffer layer\nis improved.",
        "positive": "Coherent control of current injection in zigzag graphene nanoribbons: We present Fermi's golden rule calculations of the optical carrier injection\nand the coherent control of current injection in graphene nanoribbons with\nzigzag geometry, using an envelope function approach. This system possesses\nstrongly localized states (flat bands) with a large joint density of states at\nlow photon energies; for ribbons with widths above a few tens of nanometers,\nthis system also posses large number of (non-flat) states with maxima and\nminima close to the Fermi level. Consequently, even with small dopings the\noccupation of these localized states can be significantly altered. In this\nwork, we calculate the relevant quantities for coherent control at different\nchemical potentials, showing the sensitivity of this system to the occupation\nof the edge states. We consider coherent control scenarios arising from the\ninterference of one-photon absorption at $2\\hbar\\omega$ with two-photon\nabsorption at $\\hbar\\omega$, and those arising from the interference of\none-photon absorption at $\\hbar\\omega$ with stimulated electronic Raman\nscattering (virtual absorption at $2\\hbar\\omega$ followed by emission at\n$\\hbar\\omega$). Although at large photon energies these processes follow an\nenergy-dependence similar to that of 2D graphene, the zigzag nanoribbons\nexhibit a richer structure at low photon energies, arising from divergences of\nthe joint density of states and from resonant absorption processes, which can\nbe strongly modified by doping. As a figure of merit for the injected carrier\ncurrents, we calculate the resulting swarm velocities. Finally, we provide\nestimates for the limits of validity of our model."
    },
    {
        "anchor": "Magnetic effects in sulfur-decorated graphene: The interaction between two different materials can present novel phenomena\nthat are quite different from the physical properties observed when each\nmaterial stands alone. Strong electronic correlations, such as magnetism and\nsuperconductivity, can be produced as the result of enhanced Coulomb\ninteractions between electrons. Two-dimensional materials are powerful\ncandidates to search for the novel phenomena because of the easiness of\narranging them and modifying their properties accordingly. In this work, we\nreport magnetic effects of graphene, a prototypical non-magnetic\ntwo-dimensional semi-metal, in the proximity with sulfur, a diamagnetic\ninsulator. In contrast to the well-defined metallic behaviour of clean\ngraphene, an energy gap develops at the Fermi energy for the graphene/sulfur\ncompound with decreasing temperature. This is accompanied by a steep increase\nof the resistance, a sign change of the slope in the magneto-resistance between\nhigh and low fields, and magnetic hysteresis. A possible origin of the observed\nelectronic and magnetic responses is discussed in terms of the onset of\nlow-temperature magnetic ordering. These results provide intriguing insights on\nthe search for novel quantum phases in graphene-based compounds.",
        "positive": "Comparative study of first-principles approaches for effective Coulomb\n  interaction strength $U_{\\rm eff}$ between localized $f$-electrons:\n  lanthanide metals as an example: As correlation strength has a key influence on the simulation of strongly\ncorrelated materials, many approaches have been proposed to obtain the\nparameter using first-principles calculations. However, the comparison of the\ndifferent Coulomb strengths obtained using these approaches and an\ninvestigation of the mechanisms behind them are still needed. Taking lanthanide\nmetals as an example, we research the factors that affect the effective Coulomb\ninteraction strength, $U_{\\rm eff}$, by local screened Coulomb correction\n(LSCC), linear response (LR) and constrained random-phase approximation (cRPA)\nin VASP. The $U^{\\rm LSCC}_{\\rm eff}$ value increases from 4.75 eV to 7.78 eV,\n$U^{\\rm LR}_{\\rm eff}$ is almost stable at about 6.0 eV (except for Eu, Er and\nLu), and $U^{\\rm cRPA}_{\\rm eff}$ shows a two-stage decreasing trend in both\nlight and heavy lanthanides. To investigate these differences, we established a\nscheme to analyze coexistence and competition between the orbital localization\nand the screening effect. We find that LSCC and cRPA are dominated by the\norbital localization and the screening effect, respectively, whereas LR shows a\nbalance of the competition between the two factors. Additionally, the\nperformance of these approaches is influenced by different starting points from\nPBE and PBE+$U$, especially for cRPA. Our results provide useful knowledge for\nunderstanding the $U_{\\rm eff}$ of lanthanide materials, and similar analyses\ncan also be used in the research of other correlation strength simulation\napproaches."
    },
    {
        "anchor": "Ab-initio study of the electric transport in gold nanocontacts: By employing a real-space formulation of the Kubo-Greenwood equation based on\na Green's function embedding technique combined with the fully relativistic\nspin-polarized Korringa-Kohn-Rostoker method a detailed investigation of the\nelectrical transport through atomic-scaled contacts between two Au(001)\nsemi-infinite systems is presented. Following a careful numerical test of the\nmethod the conductance of Au nanocontacts with different geometries is\ncalculated. In particular, for a contact formed by a linear chain of Au atoms a\nconductance near 1 $G_{0}$ is obtained. The influence of transition metal\nimpurities (Pd, Fe and Co) placed on various positions near the center of a\nparticular contact is also studied. We found that the conductance is very\nsensitive to the position of the magnetic impurities and that the mechanism for\nthe occurring relative changes can mainly be attributed to the impurities'\nminority $d$-band inducing resonant line-shapes in the $s$-like DOS at the\ncenter of the contact.",
        "positive": "Free-Boundary Dynamics in Elasto-plastic Amorphous Solids: The Circular\n  Hole Problem: We develop an athermal shear-transformation-zone (STZ) theory of plastic\ndeformation in spatially inhomogeneous, amorphous solids. Our ultimate goal is\nto describe the dynamics of the boundaries of voids or cracks in such systems\nwhen they are subjected to remote, time-dependent tractions. The theory is\nillustrated here for the case of a circular hole in an infinite two-dimensional\nplate, a highly symmetric situation that allows us to solve much of the problem\nanalytically. In spite of its special symmetry, this example contains many\ngeneral features of systems in which stress is concentrated near free\nboundaries and deforms them irreversibly. We depart from conventional\ntreatments of such problems in two ways. First, the STZ analysis allows us to\nkeep track of spatially heterogeneous, internal state variables such as the\neffective disorder temperature, which determines plastic response to subsequent\nloading. Second, we subject the system to stress pulses of finite duration, and\ntherefore are able to observe elasto-plastic response during both loading and\nunloading. We compute the final deformations and residual stresses produced by\nthese stress pulses. Looking toward more general applications of these results,\nwe examine the possibility of constructing a boundary-layer theory that might\nbe useful in less symmetric situations."
    },
    {
        "anchor": "An averaged cluster approach to including chemical short range order in\n  KKR-CPA: The single-site Korringa-Kohn-Rostoker Coherent Potential Approximation\n(KKR-CPA) ignores short range ordering present in disordered metallic systems.\nIn this paper, we establish a new technique to fix this shortcoming by\nembedding an averaged cluster that displays chemical short range order (SRO).\nThe degree of SRO can be tuned by externally defined order parameters. This\naveraged cluster can be embedded in the single site CPA medium, or a\nself-consistently obtained effective medium that contains SRO information. The\nvalidity of this method is demonstrated by applying it to two alloy systems -\nthe CuZn body centered cubic (BCC) solid solution, and AlCrTiV, a four-element\nBCC high entropy alloy. A comparison between the non-self-consistent and\nself-consistent modes is also provided for the two above mentioned systems. We\nmake the code available on the internet. Planned extensions to this work are\ndiscussed.",
        "positive": "DFT insights into MAX phase borides Hf2AB [A = S, Se, Te] in comparison\n  with MAX phase carbides Hf2AC [A = S, Se, Te]: In this work, density functional theory (DFT) based calculations were\nperformed to compute the physical properties (structural stability, mechanical\nbehavior, electronic, thermodynamic, and optical properties) of synthesized MAX\nphases Hf2SB, Hf2SC, Hf2SeB, Hf2SeC, Hf2TeB, and the as-yet-undiscovered MAX\ncarbide phase Hf2TeC. Calculations of formation energy, phonon dispersion\ncurves, and elastic constants confirmed the stability of the aforementioned\ncompounds. The obtained values of lattice parameters, elastic constants, and\nelastic moduli of Hf2SB, Hf2SC, Hf2SeB, Hf2SeC, and Hf2TeB showed fair\nagreement with earlier studies, whereas the values of the mentioned parameters\nfor the predicted Hf2TeC exhibit a good consequence of B replacement by C. The\nanisotropic mechanical properties are exhibited by the considered MAX phases.\nThe metallic nature and its anisotropic behavior were revealed by the\nelectronic band structure and density of states. The analysis of the thermal\nproperties Debye temperature, melting temperature, minimum thermal\nconductivity, and Gruneisen parameter confirmed that the carbide phases were\nmore suited than the boride phases considered herein. The MAX phase response to\nincoming photons further demonstrated that they were metallic. Their\nsuitability for use as coating materials to prevent solar heating was\ndemonstrated by the reflectivity spectra. Additionally, this study demonstrated\nthe impact of B replacing C in the MAX phases."
    },
    {
        "anchor": "N-polar GaN p-n junction diodes with low ideality factors: High-quality N-polar GaN p-n diodes are realized on single-crystal N-polar\nGaN bulk substrate by plasma-assisted molecular beam epitaxy. The\nroom-temperature current-voltage characteristics reveal a high on/off current\nratio of 10^11 at 4 V and an ideality factor of 1.6. As the temperature\nincreases to 200 C, the apparent ideality factor gradually approaches 2. At\nsuch high temperatures, Shockley-Read-Hall recombination times of 0.32-0.46 ns\nare estimated. The measured electroluminescence spectrum is dominated by a\nstrong near-band edge emission, while deep level and acceptor-related\nluminescence is greatly suppressed. A relatively high reverse breakdown field\nof 2.4 MV/cm without field-plates is achieved. This work indicates that the\nquality of N-polar GaN diodes is now approaching to that of their\nstate-of-the-art Ga-polar counterparts.",
        "positive": "Quasiparticle Dynamics in Reshaped Helical Dirac Cone of Topological\n  Insulators: Topological insulators (TIs) and graphene present two unique classes of\nmaterials which are characterized by spin polarized (helical) and non-polarized\nDirac-cone band structures, respectively. The importance of many-body\ninteractions that renormalize the linear bands near Dirac point in graphene has\nbeen well recognized and attracted much recent attention. However,\nrenormalization of the helical Dirac point has not been observed in TIs. Here,\nwe report the experimental observation of the renormalized quasi-particle\nspectrum with a skewed Dirac cone in a single Bi bilayer grown on Bi2Te3\nsubstrate, from angle-resolved photoemission spectroscopy. First-principles\nband calculations indicate that the quasi-particle spectra are likely\nassociated with the hybridization between the extrinsic substrate-induced Dirac\nstates of Bi bilayer and the intrinsic surface Dirac states of Bi2Te3 film at\nclose energy proximity. Without such hybridization, only single-particle Dirac\nspectra are observed in a single Bi bilayer grown on Bi2Se3, where the\nextrinsic Dirac states Bi bilayer and the intrinsic Dirac states of Bi2Se3 are\nwell separated in energy. The possible origins of many-body interactions are\ndiscussed. Our findings provide a means to manipulate topological surface\nstates."
    },
    {
        "anchor": "Exponential decay of relaxation effects at LaAlO3/SrTiO3\n  heterointerfaces: We study the decay of interface induced structural and electronic relaxation\neffects in epitaxial LaAlO3/SrTiO3 heterostructures. The results are based on\nfirst-principles band structure calculations for a multilayer configuration\nwith an ultrathin LaAlO3 layer sandwiched between bulk-like SrTiO3 layers. We\ncarry out the structure optimization for the heterointerface and investigate\nthe electronic states of the conducting interface layer, which is found to\nextend over two SrTiO3 unit cells. The decay of atomic displacements is\nanalyzed as a function of the distance to the interface, and the resulting\nexponential law is evaluated quantitatively.",
        "positive": "Dynamical Structure, Bonding, and Thermodynamics of the Superionic\n  Sublattice in alpha-AgI: Using extensive first-principles molecular dynamics calculations, we\ncharacterize the superionic phase transition and the lattice and electronic\nstructures of the archetypal Type-I superionic conductor alpha-AgI. We find\nthat superionicity is signalled by a phase transition of the silver ions alone.\nIn the superionic phase, the first silver shell surrounding an iodine displays\na distinct dynamical structure that would escape a time-averaged\ncharacterization, and we capture this structure in a set of ordering rules. The\nelectronic structure of the system demonstrates a unique chemical signature of\nthe weakest-bound silver in the first shell, which in turn is most likely to\ndiffuse. Upon melting, the silver diffusion decreases, pointing to an unusual\nentropic contribution to the stability of the superionic phase."
    },
    {
        "anchor": "Creep-fatigue interactions in a polycrystalline structural material\n  under typical high-temperature power plant operating conditions: A micromechanical model at the microscale within a crystal plasticity\nself-consistent model, is used to analyse loading histories in Type 316H\nstainless steel, common to structural components in high-temperature power\nplants. The study compares the SCM predictions on changes in mechanical\nbehaviour and creep properties to analyses via the UK R5 structural assessment\ncode. Plant-relevant cyclic-creep histories in Type 316H stainless steel at\n550C are examined with focus on the estimation of accumulated creep strain.\nThis aims to quantify how better understanding of creep deformation under\ncyclic loading can inform R5 code life assessment methods, which are strain\nbased. The effect of cyclic plasticity on primary and secondary creep is\nquantified. The levels of creep strain accumulated during different dwells,\nfollowing loading from different macroscopic stress states, is also evaluated\nand link is made to experimental observations in explaining the response. The\nimpact of displacement- and load-controlled dwells on the evolution of the\ncyclic hysteresis loop is examined which revealed how different assumptions for\ncreep strain accumulation could employ information from SCM results to reduce\nuncertainty. It also provides guidance in the development of interpolation\nframeworks for structural parameters, based on the SCM results which could be\nused directly in structural assessment and design approaches to estimate the\naccumulation of inelastic strain with a lower degree of conservatism.",
        "positive": "Effect of thermal treatments in high purity Ar on the oxidation behavior\n  of arc-PVD c-Al0.66Ti0.33N coatings: The effect of temperature in high purity Ar (low oxygen partial pressure) on\nthe oxidation and crystal phase evolution of c-Al0.66Ti0.33N arc-PVD coatings\nwas investigated. High temperature tribology in Ar jet and adhesion behavior of\nthe oxidized coating were addressed. The use of Ar protects the coating from\nthe oxidation reactions and allowed to shed light into the details and paths of\nthe nitride oxidation process. The c-Al0.66Ti0.33N nitrides were slightly\noxidized in Ar even at high temperature. The surface chemistry evaluation shows\nvery thin Al- and Ti-based oxide layers formation after 700C in Ar. However,\nthe onset formation of the rutile TiO2 oxide was detected only after 900C and\nwas clearly found by low-angle XRD diffraction after 1000C. XPS analysis of the\noxidized samples at 800C indicated the formation of extremely thin layers\nmainly composed of mixed oxides a-Al2O3 g-Al2O3 and r-TiO2. Gradual changes in\nthe chemical composition of the oxidized coatings observed at 900C clearly\ndemonstrate the formation of gradient boundaries between Al-rich and Ti-rich\noxy-nitride layers. After 1000C at least four oxides and oxi-nitrides layers\nand interlayers were found. Additionally, it is suspected that the transition\noxide phases such as c-TiO, c-Al0.54Ti2.46O0.28N4.58, alpha-Al2TiO5 and TiOxNy\nmight be precursors leading to the formation of thermodynamically stable rutile\nand alumina phases. Surface inspection after high temperature tribology in Ar\njet showed formation of tensile cracks in the wear tracks and wear processes\ndue to high size particle adhesion-abrasion and low size particle\nmicro-ploughing of hard nitrides, oxi-nitrides and brittle oxide particles.\nAdhesion tests performed after high temperature tribology in Ar showed critical\nload decrease related to cohesive and adhesive damages at the contact point of\nthe scratch track."
    },
    {
        "anchor": "Low Lattice Thermal Conductivity of a Two-Dimensional Phosphorene Oxide: A fundamental understanding of the phonon transport mechanism is important\nfor optimizing the efficiency of thermoelectric devices. In this study, we\ninvestigate the thermal transport properties of the oxidized form of\nphosphorene called phosphorene oxide (PO) by solving phonon Boltzmann transport\nequation based on first-principles density functional theory. We reveal that PO\nexhibits a much lower thermal conductivity (2.42-7.08 W/mK, at 300 K) than its\npristine counterpart as well as other two-dimensional materials. To comprehend\nthe physical origin of such low thermal conductivity, we scrutinize the\ncontribution of each phonon branch to the thermal conductivity by evaluating\nvarious mode-dependent quantities including Gruneisen parameters, anharmonic\nthreep-honon scattering rate, phase space of three-phonon scattering processes.\nOur results show that its exible puckered structure of PO leads to smaller\nsound velocities; its broken-mirror symmetry allows more ZA phonon scattering;\nand the relatively-free vibration of dangling oxygen atoms in PO gives rise to\nadditional scattering resulting in further reduction in the phonon lifetime.\nThese results can be verified by the fact that PO has larger phase space for\nthree-phonon processes than phosphorene. Furthermore we show that the thermal\nconductivity of PO can be optimized by controlling its size or its phonon mean\nfree path, indicating that PO can be a promising candidate for low-dimensional\nthermoelectric devices.",
        "positive": "Even-odd effects in magnetoresistance of ferromagnetic domain walls: Difference in density of states for the spin's majority and minority bands in\na ferromagnet changes the electrostatic potential along the domains,\nintroducing the discontinuities of the potential at domain boundaries. The\nvalue of discontinuity oscillates with number of domains. Discontinuity depends\non the positions of domain walls, their motion or collapse of domain walls in\napplied magnetic field. Large values of magnetoresistance are explained in\nterms of spin-accumulation. We suggest a new type of domain walls in nanowires\nof itinerant ferromagnets, in which the magnetization vector changes without\nrotation. Absence of transverse magnetization components allows considerable\nspin accumulation assuming the spin relaxation length, L_S, is large enough."
    },
    {
        "anchor": "Gapped Electronic Structure of Epitaxial Stanene on InSb(111): Stanene (single-layer grey tin), with an electronic structure akin to that of\ngraphene but exhibiting a much larger spin-orbit gap, offers a promising\nplatform for room-temperature electronics based on the quantum spin Hall (QSH)\neffect. This material has received much theoretical attention, but a suitable\nsubstrate for stanene growth that results in an overall gapped electronic\nstructure has been elusive; a sizable gap is necessary for room-temperature\napplications. Here, we report a study of stanene epitaxially grown on the\n(111)B-face of indium antimonide (InSb). Angle-resolved photoemission\nspectroscopy (ARPES) measurements reveal a gap of 0.44 eV, in agreement with\nour first-principles calculations. The results indicate that stanene on\nInSb(111) is a strong contender for electronic QSH applications.",
        "positive": "Transparent yttrium hydride thin films prepared by reactive sputtering: Metal hydrides have earlier been suggested for utilization in solar cells.\nWith this as a motivation we have prepared thin films of yttrium hydride by\nreactive magnetron sputter deposition. The resulting films are metallic for low\npartial pressure of hydrogen during the deposition, and black or\nyellow-transparent for higher partial pressure of hydrogen. Both metallic and\nsemiconducting transparent YHx films have been prepared directly in-situ\nwithout the need of capping layers and post-deposition hydrogenation. Optically\nthe films are similar to what is found for YHx films prepared by other\ntechniques, but the crystal structure of the transparent films differ from the\nwell-known YH3 phase, as they have an fcc lattice instead of hcp."
    },
    {
        "anchor": "Fracture of Notched Single Crystal Silicon: We study atomistically the fracture of single crystal silicon at atomically\nsharp notches with opening angles of 0 degrees (a crack), 70.53 degrees, 90\ndegrees and 125.3 degrees. Such notches occur in silicon that has been formed\nby etching into microelectromechanical structures and tend to be the initiation\nsites for failure by fracture of these structures. Analogous to the stress\nintensity factor of traditional linear elastic fracture mechanics which\ncharacterizes the stress state in the limiting case of a crack, there exists a\nsimilar parameter K for the case of the notch. In the case of silicon, a\nbrittle material, this characterization appears to be particularly valid. We\nuse three interatomic potentials: a modified Stillinger-Weber potential, the\nEnvironment-Dependent Interatomic Potential (EDIP), and the modified embedded\natom method (MEAM). Of these, MEAM gives critical K-values closest to\nexperiment. In particular the EDIP potential leads to unphysical ductile\nfailure in most geometries. Because the units of K depend on the notch angle,\nthe shape of the K versus angle plot depends on the units used. In particular\nwhen an atomic length unit is used the plot is almost flat, showing--in\nprinciple from macroscopic observations alone--the association of an atomic\nlength scale to the fracture process.",
        "positive": "Enhanced mechanical performance and bioactivity in strontium/copper\n  co-substituted diopside scaffolds: Effective scaffolds for bone tissue-engineering are those that combine\nadequate mechanical and chemical performance with osseointegrative,\nangiogenetic and anti-bacterial modes of bioactivity. To address these\nrequirements via a combined approach, we additively manufactured square strut\nscaffolds by robocasting precipitation-derived strontium/copper co-substituted\ndiopside. Microstructure, mechanical performance, bioactivity,\nbiocompatibility, and antibacterial activity were examined. The results show\nthat the presence of strontium and copper in the diopside lattice reduces the\ngrain size and increases the density of the ceramics. The compressive strength,\nhardness, and fracture toughness of the diopside showed improvement, attributed\nto a finer microstructure and improved sintering. Scaffolds had excellent\ncompressive strength with a high porosity (68 to 72 %), which is attributed to\nthe structure of the stacked square struts. All materials showed good in vitro\nbioactivity and favorable proliferation of osteogenic sarcoma cells, while\nstrontium and copper co-doped materials exhibited the strongest\nanti-Escherichia coli activity. We show that across multiple indicators this\nsystem offers pathways towards high-performance bone substitutes."
    },
    {
        "anchor": "Structural and elastic properties of amorphous carbon from simulated\n  quenching at low rates: We generate representative structural models of amorphous carbon (a-C) from\nconstant-volume quenching from the liquid with subsequent relaxation of\ninternal stresses in molecular dynamics simulations using empirical and\nmachine-learning interatomic potentials. By varying volume and quench rate we\ngenerate structures with a range of density and amorphous morphologies. We find\nthat all a-C samples show a universal relationship between hybridization, bulk\nmodulus and density despite having distinct cohesive energies. Differences in\ncohesive energy are traced back to slight changes in the distribution of\nbond-angles that will likely affect thermal stability of these structures.",
        "positive": "Uncovering vacuum level in infinite solid by real-space\n  potential-unfolding: Although real materials are finite in size, electronic structure theory is\nbuilt on the assumption of infinitely large solid, which led to a longstanding\ncontroversy: where is the vacuum level? Here, we introduce an analytic\nreal-space potential-unfolding approach to uncover the vacuum level in\ninfinitely large solid. First-principles calculations show that, in the absence\nof a physical surface, the bulk band structure, often measured with respect to\nan average bulk potential, is offset by a hereto unknown and\norientation-dependent bulk quadrupole with respect to the vacuum level. By\nidentifying intrinsic contributions of a bulk solid to its surface and\ninterface properties, our theory eliminates the ambiguities surrounding the\nphysical origin of the band alignment between matters."
    },
    {
        "anchor": "Quantum Monte Carlo Study of High Pressure Solid Molecular Hydrogen: We use the diffusion quantum Monte Carlo (DMC) method to calculate the ground\nstate phase diagram of solid molecular hydrogen and examine the stability of\nthe most important insulating phases relative to metallic crystalline molecular\nhydrogen. We develop a new method to account for finite-size errors by\ncombining the use of twist-averaged boundary conditions with corrections\nobtained using the Kwee-Zhang-Krakauer (KZK) functional in density functional\ntheory. To study band-gap closure and find the metallization pressure, we\nperform accurate quasi-particle many-body calculations using the $GW$ method.\nIn the static approximation, our DMC simulations indicate a transition from the\ninsulating Cmca-12 structure to the metallic Cmca structure at around 375 GPa.\nThe $GW$ band gap of Cmca-12 closes at roughly the same pressure. In the\ndynamic DMC phase diagram, which includes the effects of zero-point energy, the\nCmca-12 structure remains stable up to 430 GPa, well above the pressure at\nwhich the $GW$ band gap closes. Our results predict that the semimetallic state\nobserved experimentally at around 360 GPa [Phys. Rev. Lett. {\\bf 108}, 146402\n(2012)] may correspond to the Cmca-12 structure near the pressure at which the\nband gap closes. The dynamic DMC phase diagram indicates that the hexagonal\nclose packed $P6_3/m$ structure, which has the largest band gap of the\ninsulating structures considered, is stable up to 220 GPa. This is consistent\nwith recent X-ray data taken at pressures up to 183 GPa [Phys. Rev. B {\\bf 82},\n060101(R) (2010)], which also reported a hexagonal close packed arrangement of\nhydrogen molecules.",
        "positive": "Diffusion mechanism of exciplex. 2. Energy transfer mechanism: Excited-state charge-transfer complexes (exciplexes) have been actively\nexploited in organic optoelectronic devices to improve performance; however,\ndiffusion of exciplexes has not been actively studied despite its influence on\nperformance due to the lack of apparent charge-transfer absorption. In the\npreceding paper, we studied the energy transfer (ET) from exciplexes to\nexciplex-forming pairs in relation to the charge-transfer absorption of the\nexciplex state, resulting in the exciplex diffusion. In this paper, we report\nthat the ET takes place dominantly via the Dexter-type exchange mechanism, from\nthe exponential decrease of the ET rate constant with separation between\nexciplexes."
    },
    {
        "anchor": "Comparison of band-fitting and Wannier-based model construction for\n  WSe$_2$: Transition metal dichalcogenide materials $MX_2 (M=Mo,W;X=S,Se)$ are being\nthoroughly studied due to their novel two-dimensional structure, that is\nassociated with exceptional optical and transport properties. From a\ncomputational point of view, Density Functional Theory simulations perform very\nwell in these systems and are an indispensable tool to predict and complement\nexperimental results. However, due to the time and length scales where even the\nmost efficient DFT implementations can reach today, this methodology suffers of\nstringent limitations to deal with finite temperature simulations or\nelectron-lattice coupling when studying excitation states: the unit cells\nrequired to study, for instance, systems with thermal fluctuations or large\npolarons would require a large computational power. Multi-scale techniques,\nlike the recently proposed Second Principles Density Functional Theory, can go\nbeyond these limitations but require the construction of tight-binding models\nfor the systems under investigation. In this work, we compare two such methods\nto construct the bands of WSe$_2$. In particular, we compare the result of (i)\nWannier-based model construction with (ii) the band fitting method of Liu and\nco-workers where the top of the valence band and the bottom of the conduction\nband are modeled by three bands symmetrized to have mainly Tungsten $d_{z^2}$,\n$d_{xy}$ and $d_{x^2-y^2}$ character. Our results emphasize the differences\nbetween these two approaches and how band-fitting model construction leads to\nan overestimation of the localization of the real-space basis in a\ntight-binding representation.",
        "positive": "Electronic properties of bilayer graphenes strongly coupled to\n  interlayer stacking and an external electric field: Bilayer graphene (BLG) with a tunable bandgap appears interesting as an\nalternative to graphene for practical applications, thus its transport\nproperties are being actively pursued. Using density functional theory and\nperturbation analysis, we investigated, under an external electric field, the\nelectronic properties of BLGs in various stackings relevant to recently\nobserved complex structures. We established the first phase diagram summarizing\nthe stacking-dependent gap openings of BLGs for a given field. We further\nidentified high-density midgap states, localized on grain boundaries, even\nunder a strong field, which can considerably reduce overall transport gap."
    },
    {
        "anchor": "Phonons and Colossal Thermal Expansion Behavior of Ag3Co(CN)6 and\n  Ag3Fe(CN)6: Recently colossal positive volume thermal expansion has been found in the\nframework compounds Ag3Co(CN)6 and Ag3Fe(CN)6. Phonon spectra have been\nmeasured using the inelastic neutron scattering technique as a function of\ntemperature and pressure. The data has been analyzed using ab-initio\ncalculations. We find that the bonding is very similar in both compounds. At\nambient pressure modes in the intermediate frequency part of the vibrational\nspectra in the Co compound are shifted to slightly higher energies as compared\nto the Fe compound. The temperature dependence of the phonon spectra gives\nevidence for large explicit anharmonic contribution to the total anharmonicity\nfor low-energy modes below 5 meV. We found that modes are mainly affected by\nthe change in the size of unit cell, which in turn changes the bond lengths and\nvibrational frequencies. Thermal expansion has been calculated via the volume\ndependence of phonon spectra. Our analysis indicates that Ag phonon modes in\nthe energy range from 2 to 5 meV are strongly anharmonic and major contributors\nto thermal expansion in both compounds. The application of pressure hardens the\nlow-energy part of the phonon spectra involving Ag vibrations and confirms the\nhighly anharmonic nature of these modes.",
        "positive": "Yielding in multi-component metallic glasses: Universal signatures of\n  elastic modulus heterogeneities: Sheared multi-component bulk metallic glasses are characterized by both\nchemical and structural disorder that define their properties. We investigate\nthe behavior of the local, microstructural elastic modulus across the plastic\nyielding transition in six Ni-based multi-component glasses, that are\ncharacterized by compositional features commonly associated with solid solution\nformability. We find that elastic modulus fluctuations display consistent\npercolation characteristics pointing towards universal behavior across chemical\ncompositions and overall yielding sharpness characteristics. Elastic\nheterogeneity grows upon shearing via the percolation of elastically soft\nclusters within an otherwise rigid amorphous matrix, confirming prior\ninvestigations in granular media and colloidal glasses. We find clear\nsignatures of percolation transition with spanning clusters that are\nuniversally characterized by scale-free characteristics and critical scaling\nexponents. The spatial correlation length and mean cluster size tend to diverge\nprior to yielding, with associated critical exponents that exhibit fairly weak\ndependence on compositional variations as well as macroscopic stress-strain\ncurve details."
    },
    {
        "anchor": "Prediction model of band-gap for AX binary compounds by combination of\n  density functional theory calculations and machine learning techniques: Machine learning techniques are applied to make prediction models of the G0W0\nband-gaps for 156 AX binary compounds using Kohn-Sham band-gaps and other\nfundamental information of constituent elements and crystal structure as\npredictors. Ordinary least square regression (OLSR), least absolute shrinkage\nand selection operator (LASSO) and non-linear support vector regression (SVR)\nmethods are applied with several levels of predictor sets. When the Kohn-Sham\nband-gap by GGA (PBE) or modified Becke-Johnson (mBJ) is used as a single\npredictor, OLSR model predicts the G0W0 band-gap of a randomly selected test\ndata with the root mean square error (RMSE) of 0.54 eV. When Kohn-Sham band gap\nby PBE and mBJ methods are used together with a set of various forms of\npredictors representing constituent elements and crystal structures, RMSE\ndecreases significantly. The best model by SVR yields the RMSE of 0.18 eV. A\nlarge set of band-gaps estimated in this way should be useful as predictors for\nmaterials exploration.",
        "positive": "Spin glass behavior in amorphous Cr2Ge2Te6 phase-change alloy: The layered crystal structure of Cr2Ge2Te6 shows ferromagnetic ordering at\nthe two-dimensional limit, which holds promise for spintronic applications.\nHowever, external voltage pulses can trigger amorphization of the material in\nnanoscale electronic devices, and it is unclear whether the loss of structural\nordering leads to a change in magnetic properties. Here, we demonstrate that\nCr2Ge2Te6 preserves the spin-polarized nature in the amorphous phase, but\nundergoes a magnetic transition to a spin glass state below 20 K.\nQuantum-mechanical computations reveal the microscopic origin of this\ntransition in spin configuration: it is due to strong distortions of the\nCr-Te-Cr bonds, connecting chromium-centered octahedra, and to the overall\nincrease in disorder upon amorphization. The tunable magnetic properties of\nCr2Ge2Te6 could be exploited for multifunctional, magnetic phase-change devices\nthat switch between crystalline and amorphous states."
    },
    {
        "anchor": "Training Induced Positive Exchange Bias in NiFe/IrMn Bilayers: Positive exchange bias has been observed in the\nNi$_{81}$Fe$_{19}$/Ir$_{20}$Mn$_{80}$ bilayer system via soft x-ray resonant\nmagnetic scattering. After field cooling of the system through the blocking\ntemperature of the antiferromagnet, an initial conventional negative exchange\nbias is removed after training i. e. successive magnetization reversals,\nresulting in a positive exchange bias for a temperature range down to 30 K\nbelow the blocking temperature (450 K). This new manifestation of magnetic\ntraining is discussed in terms of metastable magnetic disorder at the\nmagnetically frustrated interface during magnetization reversal.",
        "positive": "Shrinking annuli mechanism and stage-dependent rate capability of\n  thin-layer graphite electrodes for lithium-ion batteries: The kinetic performance of graphite particles is difficult to deconvolute\nfrom half-cell experiments, where the influences of the working electrode\nporosity and the counter electrode contribute nonlinearly to the\nelectrochemical re-sponse. Therefore, thin-layer electrodes of circa 1 {\\mu}m\nthickness were prepared with standard, highly crystalline graphite particles to\nevaluate their rate capability. The performance was evaluated based on the\ndifferent stage transitions. We found that the tran-sitions towards the dense\nstages 1 and 2 with LiC6 in-plane densi-ty are one of the main rate limitations\nfor charge and discharge. But surprisingly, the transitions towards the dilute\nstages 2L, 3L, 4L, and 1L progress very fast and can even compensate for the\ninitial diffusion limitations of the dense stage transitions during discharge.\nWe show the existence of a substantial difference between the diffusion\ncoefficients of the liquid-like stages and the dense stages. We also\ndemonstrate that graphite can be charged at a rate of ~6C (10 min) and\ndischarged at 600C (6 s) while maintaining 80 % of the total specific charge\nfor particles of 3.3 {\\mu}m median diameter. Based on these findings, we\npropose a shrinking annuli mechanism which describes the propagation of the\ndifferent stages in the particle at medium and high rates. Besides the limited\napplicable overpotential during charge, this mechanism can explain the\nlong-known but as yet unexplained asymmetry between the charge and discharge\nrate performance of lithium intercalation in graphite."
    },
    {
        "anchor": "Energetics and cathode voltages of LiMPO$_4$ olivines (M = Fe, Mn) from\n  extended Hubbard functionals: Transition-metal compounds pose serious challenges to first-principles\ncalculations based on density-functional theory (DFT), due to the inability of\nmost approximate exchange-correlation functionals to capture the localization\nof valence electrons on their $d$ states, essential for a predictive modeling\nof their properties. In this work we focus on two representatives of a well\nknown family of cathode materials for Li-ion batteries, namely the orthorhombic\nLiMPO$_4$ olivines (M = Fe, Mn). We show that extended Hubbard functionals with\non-site ($U$) and inter-site ($V$) interactions (so called DFT+U+V) can predict\nthe electronic structure of the mixed-valence phases, the formation energy of\nthe materials with intermediate Li contents, and the overall average voltage of\nthe battery with remarkable accuracy. We find, in particular, that the\ninclusion of inter-site interactions in the corrective Hamiltonian improves\nconsiderably the prediction of thermodynamic quantities when electronic\nlocalization occurs in the presence of significant interatomic hybridization\n(as is the case for the Mn compound), and that the self-consistent evaluation\nof the effective interaction parameters as material- and ground-state-dependent\nquantities allows the prediction of energy differences between different phases\nand concentrations.",
        "positive": "Find The Optimized Structure of 5CBs: We use density functional theory (DFT) to investigate the geometric and\nelectronic structures of multiple 5CB molecules. There are three parts for this\nresearch, test of the arrangement property of the 5CB molecule, calculation of\ntwo 4-n-pentyl-4-cyanobiphenyl (5CB), and four molecules 5CB structure\narrangement. First part reveals the result, which the two 5CBs pointing in\nopposite directions case possesses lower total energy, that has the same result\nof the optimized caused by the nematic property of 5CBs. In the result of two\n5CBs calculation, two 5CBs optimized structures always appears at least one\npair of parallel plains formed by the head benzene of one 5CB and the carbon\nchain. In the four 5CBs optimized structure case, we can find out several pairs\nof parallel plains consist of benzene plains and one parallel plain in two\ncarbon chain."
    },
    {
        "anchor": "Light-Induced Charge Density Wave in LaTe$_3$: When electrons in a solid are excited with light, they can alter the free\nenergy landscape and access phases of matter that are beyond reach in thermal\nequilibrium. This accessibility becomes of vast importance in the presence of\nphase competition, when one state of matter is preferred over another by only a\nsmall energy scale that, in principle, is surmountable by light. Here, we study\na layered compound, LaTe$_3$, where a small in-plane (a-c plane) lattice\nanisotropy results in a unidirectional charge density wave (CDW) along the\nc-axis. Using ultrafast electron diffraction, we find that after\nphotoexcitation, the CDW along the c-axis is weakened and subsequently, a\ndifferent competing CDW along the a-axis emerges. The timescales characterizing\nthe relaxation of this new CDW and the reestablishment of the original CDW are\nnearly identical, which points towards a strong competition between the two\norders. The new density wave represents a transient non-equilibrium phase of\nmatter with no equilibrium counterpart, and this study thus provides a\nframework for unleashing similar states of matter that are \"trapped\" under\nequilibrium conditions.",
        "positive": "Structure and optical properties of Cd substituted ZnO (Zn1-xCdxO)\n  nanostructures synthesized by high pressure solution route: We report synthesis of Cd substituted ZnO nanostructures (Zn1-xCdxO with x\nupto \\approx .09) by high pressure solution growth method. The synthesized\nnanostructures comprise of nanocrystals that are both particles (~ 10-15 nm)\nand rods which grow along (002) direction as established by Transmission\nelectron microscope (TEM) and X-ray diffraction (XRD) analysis. Rietveld\nanalysis of the XRD data shows monotonous increase of the unit cell volume with\nthe increase of Cd concentration. The optical absorption as well as the\nphotoluminescence (PL) shows red shift on Cd substitution. The line width of\nthe PL spectrum is related to the strain inhomogenity and it peaks in the\nregion where the CdO phase separates from the Zn1-xCdxO nanostructures. The\ntime resolved photoemission showed a long lived (~10ns) component. We propose\nthat the PL behavior of the Zn1-xCdxO is dominated by strain in the sample with\nthe redshift of the PL linked to the expansion of the unit cell volume on Cd\nsubstitution."
    },
    {
        "anchor": "Solute-solute interactions in intermetallic compounds: Two types of solute-solute interactions are investigated in this work.\nQuadrupole interactions caused by nearby Ag-solute atoms were measured at\nnuclei of 111In/Cd solute probe atoms in the binary compound GdAl2 using the\nmethod of perturbed angular correlation of gamma rays (PAC). Locations of\nIn-probes and Ag-solutes on both Gd- and Al-sublattices were identified by\ncomparing site fractions in Gd-poor and Gd-rich GdAl2(Ag) samples. Interaction\nenthalpies between solute-atom pairs were determined from temperature\ndependences of observed site fractions. Repulsive interactions were observed\nfor close-neighbor complexes In/Gd/+Ag/Gd/ and In/Gd/+Ag/Al/ pairs, whereas a\nslightly attractive interaction was observed for In/Al/+Ag/Al/. Interaction\nenthalpies were all in the range +/- 0.15 eV. Temperature dependences of site\nfractions of In-probes on locally defect-free Gd- and Al-sites yields a\ntransfer enthalpy that was found to be 0.343 eV in a previous study of undoped\nGdAl2. The corresponding values in GdAl2(Ag) samples are much smaller. This is\nattributed to competition of In- and Ag-solutes to occupy sites of the same\nsublattice. While the difference in site-enthalpies of In-solutes on Gd- and\nAl-sites is temperature independent, it is proposed that the transfer of\nAg-solutes from Gd- to Al-sites leads to a large temperature dependence of\ndegeneracies of levels available to In-solutes, resulting in an effective\ntransfer enthalpy that is much smaller than the difference in site-enthalpies.",
        "positive": "Kagome silicene: a novel exotic form of two-dimensional epitaxial\n  silicon: Since the discovery of graphene, intensive efforts have been made in search\nof novel two-dimensional (2D) materials. Decreasing the materials\ndimensionality to their ultimate thinness is a promising route to unveil new\nphysical phenomena, and potentially improve the performance of devices. Among\nrecent 2D materials, analogs of graphene, the group IV elements have attracted\nmuch attention for their unexpected and tunable physical properties. Depending\non the growth conditions and substrates, several structures of silicene,\ngermanene, and stanene can be formed. Here, we report the synthesis of a Kagome\nlattice of silicene on aluminum (111) substrates. We provide evidence of such\nan exotic 2D Si allotrope through scanning tunneling microscopy (STM)\nobservations, high-resolution core-level (CL) and angle-resolved photoelectron\nspectroscopy (ARPES) measurements, along with Density Functional Theory\ncalculations."
    },
    {
        "anchor": "Electron-polaron dichotomy of charge carriers in perovskite oxides: Many transition metal oxides (TMOs) are Mott insulators due to strong Coulomb\nrepulsion between electrons, and exhibit metal-insulator transitions (MITs)\nwhose mechanisms are not always fully understood. Unlike most TMOs, minute\ndoping in CaMnO3 induces a metallic state without any structural\ntransformations. This material is thus an ideal platform to explore band\nformation through the MIT. Here, we use angle-resolved photoemission\nspectroscopy to visualize how electrons delocalize and couple to phonons in\nCaMnO3. We show the development of a Fermi surface where mobile electrons\ncoexist with heavier carriers, strongly coupled polarons. The latter originate\nfrom a boost of the electron-phonon interaction (EPI). This finding brings to\nlight the role that the EPI can play in MITs even caused by purely electronic\nmechanisms. Our discovery of the EPI-induced dichotomy of the charge carriers\nexplains the transport response of Ce-doped CaMnO3 and suggests strategies to\nengineer quantum matter from TMOs.",
        "positive": "Effect of tungsten on vacancy behaviors in Ta-W alloys from\n  first-principles: Alloying elements play an important role in the design of plasma facing\nmaterials with good comprehensive properties. Based on first-principles\ncalculations, the stability of alloying element W and its interaction with\nvacancy defects in Ta-W alloys are studied. The results show that W tends to\ndistribute dispersedly in Ta lattice, and is not likely to form precipitation\neven with the coexistence of vacancy. The aggregation behaviors of W and\nvacancy can be affected by their concentration competition. The increase of W\natoms has a negative effect on the vacancy clustering, as well as delays the\nvacancy nucleation process, which is favorable to the recovery of point\ndefects. Our results are in consistent with the defect evolution observed in\nirradiation experiments in Ta-W alloys. Our calculations suggest that Ta is a\npotential repairing element that can be doped into Ta-based materials to\nimprove their radiation resistance."
    },
    {
        "anchor": "Interfacial Magnetoelectric Coupling in Tri-component Superlattices: Using first-principles density functional theory, we investigate the\ninterfacial magnetoelectric coupling in a tri-component superlattice composed\nof a ferromagnetic metal (FM), ferroelectric (FE), and normal metal (NM). Using\nFe/FE/Pt as a model system, we show that a net and cumulative interfacial\nmagnetization is induced in the FM metal near the FM/FE interface. A carefully\nanalysis of the magnetic moments in Fe reveals that the interfacial\nmagnetization is a consequence of a complex interplay of interfacial charge\ntransfer, chemical bonding, and spin dependent electrostatic screening. The\nlast effect is linear in the FE polarization, is switchable upon its reversal,\nand yields a substantial interfacial magnetoelectric coupling.",
        "positive": "Ice XV: a new thermodynamically stable phase of ice: A new phase of ice, named ice XV, has been identified and its structure\ndetermined by neutron diffraction. Ice XV is the hydrogen-ordered counterpart\nof ice VI and is thermodynamically stable at temperatures below ~130 K in the\n0.8 to 1.5 GPa pressure range. The regions of stability in the medium pressure\nrange of the phase diagram have thus been finally mapped, with only\nhydrogen-ordered phases stable at 0 K. The ordered ice XV structure is\nantiferroelectric, in clear disagreement with recent theoretical calculations\npredicting ferroelectric ordering."
    },
    {
        "anchor": "A thermo-mechanical explanation for the topology of crack patterns\n  observed on the surface of charred wood and particle fibreboard: In the assessment of wood charring, it was believed for a long time that\nphysicochemical processes were responsible for the creation of cracking\npatterns on the charring wood surface. This implied no possibility to\nrigorously explain the crack topology. In this paper we show instead that below\nthe pyrolysis temperatures, a primary global macro-crack pattern is already\ncompletely established by means of a thermomechanical instability phenomenon.\nFirst we report experimental observations of the crack patterns on orthotropic\n(wood) and isotropic (Medium Density Fibreboard) materials in inert atmosphere.\nThen we solve the 3D thermomechanical buckling problem numerically by using the\nFinite Element Method, and show that the different crack topologies can be\nexplained qualitatively by the simultaneous thermal expansion and softening,\ntaking into account the directional dependence of the elastic properties.\nFinally, we formulate a 2D model for a soft layer bonded to an elastic\nsubstrate, and find an equation predicting the inter-crack distance in the main\ncrack-pattern for the orthotropic case. We also derive a formula for the\ncritical thermal stress above which the plane surface will wrinkle and buckle.\nThe results can be used for finding new ways to prevent or delay the crack\nformation, leading to improved fire safety of wood-based products.",
        "positive": "Low temperature (Ts/Tm < 0.1) epitaxial growth of HfN/MgO(001) via\n  reactive HiPIMS with metal-ion synchronized substrate bias: Low-temperature epitaxial growth of refractory transition-metal nitride thin\nfilms by means of physical vapor deposition has been a recurring theme in\nadvanced thin-film technology for several years. In the present study,\n150-nm-thick epitaxial HfN layers are grown on MgO(001) by reactive\nhigh-impulse magnetron sputtering (HiPIMS) with no external substrate heating.\nMaximum film growth temperatures Ts due to plasma heating range from 70-150\n{\\deg}C, corresponding to Ts/Tm = 0.10-0.12 (in which Tm is the HfN melting\npoint in K). During HiPIMS, gas and sputtered-metal ion fluxes incident at the\ngrowing film surface are separated in time due to strong gas rarefaction and\nthe transition to a metal-ion dominated plasma. In the present experiments, a\nnegative bias of 100 V is applied to the substrate, either continuously during\nthe entire deposition or synchronized with the metal-rich portion of the ion\nflux. Two different sputtering-gas mixtures, Ar/N2 and Kr/N2, are employed in\norder to probe effects associated with the noble-gas mass and ionization\npotential. The combination of x-ray diffraction, high-resolution\nreciprocal-lattice maps, and high-resolution cross-sectional transmission\nelectron microscopy analyses establish that all HfN films have a cube-on-cube\norientational relationship with the substrate, i.e., [001]HfN||[001]MgO and\n(100)HfN||(100)MgO. Layers grown with continuous substrate bias, in either\nAr/N2 or Kr/N2, exhibit a relatively high mosaicity and a high concentration of\ntrapped inert gas. In distinct contrast, layers grown in Kr/N2 with the\nsubstrate bias synchronized to the metal-ion-rich portion of HiPIMS pulses,\nhave much lower mosaicity, no measurable inert-gas incorporation, and a\nhardness of 25.7 GPa, in good agreement with results for epitaxial HfN(001)\nlayers grown at Ts = 650 C (Ts/Tm = 0.26)."
    },
    {
        "anchor": "Manipulating femtosecond magnetism through pressure: First-principles\n  calculations: Inspired by a recent pressure experiment in fcc Ni, we propose a simple\nmethod to use pressure to investigate the laser-induced femtosecond magnetism.\nSince the pressure effect on the electronic and magnetic properties can be well\ncontrolled experimentally, this leaves little room for ambiguity when compared\nwith theory. Here we report our theoretical pressure results in fcc Ni:\nPressure first suppresses the spin moment reduction, and then completely\ndiminishes it; further increase in pressure to 40 GPa induces a\ndemagnetization-to-magnetization transition. To reveal its microscopic origin,\nwe slide through the L-U line in the Brillouin zone and find two essential\ntransitions are responsible for this change, where the pressure lowers two\nvalence bands, resulting in an off-resonant excitation and thus a smaller spin\nmoment reduction. In the spin-richest L-W-W' plane, two spin contours are\nformed; as pressure increases, the contour size retrieves and its intensity is\nreduced to zero eventually, fully consistent with the spin-dipole factor\nprediction. These striking features are detectable in time- and spin-resolved\nphotoemission experiments.",
        "positive": "Observation of charge-to-spin conversion with giant efficiency at\n  Ni$_{0.8}$Fe$_{0.2}$/Bi$_{2}$WO$_{6}$ interface: Magnetization switching using spin-orbit torque offers a promising route to\ndeveloping non-volatile memory technologies. The prerequisite, however, is the\ncharge-to-spin current conversion, which has been achieved traditionally by\nharnessing the spin-orbit interaction in heavy metals, topological insulators,\nand heterointerfaces hosting a high-mobility two-dimensional electron gas.\nHere, we report the observation of charge-to-spin current conversion at the\ninterface between ferromagnetic Ni$_{0.8}$Fe$_{0.2}$ and ferroelectric\nBi$_{2}$WO$_{6}$ thin films. The resulting spin-orbit torque consists of\ndamping-like and field-like components, and the estimated efficiency amounts to\nabout 0.48 $\\pm$ 0.02, which translates to 0.96 $\\pm$ 0.04 nm$^{-1}$ in terms\nof interfacial efficiency. These numbers are comparable to contemporary\nspintronic materials exhibiting giant spin-orbit torque efficiency. We suggest\nthat the Rashba Edelstein effect underpins the charge-to-spin current\nconversion on the interface side of Ni$_{0.8}$Fe$_{0.2}$. Further, we provide\nan intuitive explanation for the giant efficiency in terms of the spin-orbit\nproximity effect, which is enabled by orbital hybridization between W and Ni\n(Fe) atoms across the interface. Our work highlights that Aurivillius compounds\nare a potential addition to the emerging transition metal oxide-based\nspin-orbit materials."
    },
    {
        "anchor": "Magnetoresistance anomaly during the electrical triggering of a\n  metal-insulator transition: Phase separation naturally occurs in a variety of magnetic materials and it\noften has a major impact on both electric and magnetotransport properties. In\nresistive switching systems, phase separation can be created on demand by\ninducing local switching, which provides an opportunity to tune the electronic\nand magnetic state of the device by applying voltage. Here we explore the\nmagnetotransport properties in the ferromagnetic oxide (La,Sr)MnO3 (LSMO)\nduring the electrical triggering of an intrinsic metal-insulator transition\n(MIT) that produces volatile resistive switching. This switching occurs in a\ncharacteristic spatial pattern, i.e., the formation of an insulating barrier\nperpendicular to the current flow, enabling an electrically actuated\nferromagnetic-paramagnetic-ferromagnetic phase separation. At the threshold\nvoltage of the MIT triggering, both anisotropic and colossal magnetoresistances\nexhibit anomalies including a large increase in magnitude and a sign flip.\nComputational analysis revealed that these anomalies originate from the\ncoupling between the switching-induced phase separation state and the intrinsic\nmagnetoresistance of LSMO. This work demonstrates that driving the MIT material\ninto an out-of-equilibrium resistive switching state provides the means to\nelectrically control of the magnetotransport phenomena.",
        "positive": "Solution blending preparation of polycarbonate/graphene composite:\n  boosting the mechanical and electrical properties: We report on the preparation of polycarbonate-based graphene (PC/G)\ncomposites, by using a simple and scalable solution blending method to disperse\nsingle (SLG) and few layer (FLG) graphene flakes, prepared by liquid phase\nexfoliation (LPE), in the polymer matrix. A solvent-exchange process is carried\nout to re-disperse the exfoliated SLG/FLG flakes in an environmentally friendly\nsolvent, i.e. 1,3dioxolane, which is also used to dissolve the polycarbonate\npellets, thus facilitating the mixing of the polymer dispersion with the\nSLG/FLG flakes. The loading of SLG/FLG flakes improves the mechanical and\nthermal properties, as well as the electrical conductivity of the polymer,\nreaching a +26% improvement of the elastic modulus at 1 wt% loading, and an\nelectrical conductivity 10^-3 S m^-1 at 10 wt% with a percolation threshold\nachieved at 0.55 vol%. The as-prepared PC/G composite with the aforementioned\nreinforced properties can be a promising material for 3D printing-based\napplications."
    },
    {
        "anchor": "Excitons in van der Waals heterostructures: The important role of\n  dielectric screening: The existence of strongly bound excitons is one of the hallmarks of the newly\ndiscovered atomically thin semi-conductors. While it is understood that the\nlarge binding energy is mainly due to the weak dielectric screening in two\ndimensions (2D), a systematic investigation of the role of screening on 2D\nexcitons is still lacking. Here we provide a critical assessment of a widely\nused 2D hydrogenic exciton model which assumes a dielectric function of the\nform {\\epsilon}(q) = 1 + 2{\\pi}{\\alpha}q, and we develop a quasi-2D model with\na much broader applicability. Within the quasi-2D picture, electrons and holes\nare described as in-plane point charges with a finite extension in the\nperpendicular direction and their interaction is screened by a dielectric\nfunction with a non-linear q-dependence which is computed ab-initio. The\nscreened interaction is used in a generalized Mott-Wannier model to calculate\nexciton binding energies in both isolated and supported 2D materials. For\nisolated 2D materials, the quasi-2D treatment yields results almost identical\nto those of the strict 2D model and both are in good agreement with ab-initio\nmany-body calculations. On the other hand, for more complex structures such as\nsupported layers or layers embedded in a van der Waals heterostructure, the\nsize of the exciton in reciprocal space extends well beyond the linear regime\nof the dielectric function and a quasi-2D description has to replace the 2D\none. Our methodology has the merit of providing a seamless connection between\nthe strict 2D limit of isolated monolayer materials and the more bulk-like\nscreening characteristics of supported 2D materials or van der Waals\nheterostructures.",
        "positive": "Characteristic lengthscales of the electrically-induced\n  insulator-to-metal transition: Some correlated materials display an insulator-to-metal transition as the\ntemperature is increased. In most cases this transition can also be induced\nelectrically, resulting in volatile resistive switching due to the formation of\na conducting filament. While this phenomenon has attracted much attention due\nto potential applications, many fundamental questions remain unaddressed. One\nof them is its characteristic lengths: what sets the size of these filaments,\nand how does this impact resistive switching properties. Here we use a\ncombination of wide-field and scattering-type scanning near-field optical\nmicroscopies to characterize filament formation in NdNiO3 and SmNiO3 thin\nfilms. We find a clear trend: smaller filaments increase the current density,\nyielding sharper switching and a larger resistive drop. With the aid of\nnumerical simulations, we discuss the parameters controlling the filament width\nand, hence, the switching properties."
    },
    {
        "anchor": "Critical topology and pressure-induced superconductivity in the van der\n  Waals compound AuTe2Br: The study on quantum spin Hall effect and topological insulators formed the\nprologue to the surge of research activities in topological materials in the\npast decade. Compared to intricately engineered quantum wells,\nthree-dimensional weak topological insulators provide a natural route to the\nquantum spin Hall effect, due to the adiabatic connection between them and a\nstack of quantum spin Hall insulators, and the convenience in exfoliation of\nsamples associated with their van der Waals-type structure. Despite these\nadvantages, both theoretical prediction and experimental identification of weak\ntopological insulators remain scarce. Here, based on first-principles\ncalculations, we show that AuTe2Br locates at the boundary between a strong and\na weak topological insulating state. More interestingly, the critical topology\nof AuTe2Br persists up to an applied pressure of ~ 15.4 GPa before a structural\nphase transition accompanied by a change of electronic topology and the onset\nof superconductivity. Our results establish AuTe2Br as a new candidate for weak\ntopological insulators with the potential to realize various other topological\nphases of matter.",
        "positive": "Kinetics-Limited Two-Step Growth of van der Waals Puckered Honeycomb Sb\n  Monolayer: Puckered honeycomb Sb monolayer, the structural analog of black phosphorene,\nhas been recently successfully grown by means of molecular beam epitaxy.\nHowever, little is known to date about the growth mechanism for such puckered\nhoneycomb monolayer. In this study, by using scanning tunneling microscopy in\ncombination with first-principles density functional theory calculations, we\nunveil that the puckered honeycomb Sb monolayer takes a kinetics-limited\ntwo-step growth mode. As the coverage of Sb increases, the Sb atoms firstly\nform the distorted hexagonal lattice as the half layer, and then the distorted\nhexagonal half-layer transforms into the puckered honeycomb lattice as the full\nlayer. These results provide the atomic-scale insight in understanding the\ngrowth mechanism of puckered honeycomb monolayer, and can be instructive to the\ndirect growth of other monolayers with the same structure."
    },
    {
        "anchor": "Large-Gap Quantum Spin Hall Insulator in single layer bismuth\n  monobromide Bi$_{4}$Br$_{4}$: Quantum spin Hall (QSH) insulators have gapless topological edge states\ninside the bulk band gap, which can serve as dissipationless spin current\nchannels protected by the time-reversal symmetry. The major challenge currently\nis to find suitable materials for this topological state. Here, we predict a\nnew large-gap QSH insulator with bulk direct band gap of $\\sim$0.18 eV, in\nsingle-layer Bi$_{4}$Br$_{4}$, which could be exfoliated from its\nthree-dimensional bulk material due to the weakly-bonded layered structure. The\nband gap of single-layer Bi$_{4}$Br$_{4}$ is tunable via strain engineering,\nand the QSH phase is robust against external strain. In particular, because\nthis material consists of special one-dimensional molecular chain as its basic\nbuilding block, the single layer Bi$_{4}$Br$_{4}$ could be easily torn to\nribbons with clean and atomically sharp edges, which are much desired for the\nobservation and application of topological edge states. Our work thus provides\na new promising material for experimental studies and practical applications of\nQSH effect.",
        "positive": "High Pressure Thermoelasticity of Body-centered Cubic Tantalum: We have investigated the thermoelasticity of body-centered cubic (bcc)\ntantalum from first principles by using the linearized augmented plane wave\n(LAPW) and mixed--basis pseudopotential methods for pressures up to 400 GPa and\ntemperatures up to 10000 K. Electronic excitation contributions to the free\nenergy were included from the band structures, and phonon contributions were\nincluded using the particle-in-a-cell (PIC) model. The computed elastic\nconstants agree well with available ultrasonic and diamond anvil cell data at\nlow pressures, and shock data at high pressures. The shear modulus $c_{44}$ and\nthe anisotropy change behavior with increasing pressure around 150 GPa because\nof an electronic topological transition. We find that the main contribution of\ntemperature to the elastic constants is from the thermal expansivity. The PIC\nmodel in conjunction with fast self-consistent techniques is shown to be a\ntractable approach to studying thermoelasticity."
    },
    {
        "anchor": "Hydrogen embrittlement of twinning-induced plasticity steels:\n  contribution of segregation to twin boundaries: Metallic materials, especially steel, underpin transportation technologies.\nHigh-manganese twinning induced plasticity (TWIP) austenitic steels exhibit\nexceptional strength and ductility from twins, low-energy microstructural\ndefects that form during plastic loading. Their high-strength could help\nlight-weighting vehicles, and hence cut carbon emissions. TWIP steels are\nhowever very sensitive to hydrogen embrittlement that causes dramatic losses of\nductility and toughness leading to catastrophic failure of engineering parts.\nHere, we examine the atomic-scale chemistry and interaction of hydrogen with\ntwin boundaries in a model TWIP steel by using isotope-labelled atom probe\ntomography, using tritium to avoid overlap with residual hydrogen. We reveal\nco-segregation of tritium and, unexpectedly, oxygen to coherent twin\nboundaries, and discuss their combined role in the embrittlement of these\npromising steels.",
        "positive": "Tailoring Vanadium Dioxide Film Orientation using Nanosheets: A Combined\n  Microscopy, Diffraction, Transport and Soft X-ray in Transmission Study: VO2 is a much-discussed material for oxide electronics and neuromorphic\ncomputing applications. Here, heteroepitaxy of vanadium dioxide (VO2) was\nrealized on top of oxide nanosheets that cover either the amorphous silicon\ndioxide surfaces of Si substrates or X-ray transparent silicon nitride\nmembranes. The out-of-plane orientation of the VO2 thin films was controlled at\nwill between (011)M1/(110)R and (-402)M1/(002)R by coating the bulk substrates\nwith Ti0.87O2 and NbWO6 nanosheets, respectively, prior to VO2 growth.\nTemperature dependent X-ray diffraction and automated crystal orientation\nmapping in microprobe TEM mode (ACOM-TEM) characterized the high phase purity,\nthe crystallographic and orientational properties of the VO2 films. Transport\nmeasurements and soft X-ray absorption in transmission are used to probe the\nVO2 metal-insulator transition, showing results of a quality equal to those\nfrom epitaxial films on bulk single-crystal substrates. Successful local\nmanipulation of two different VO2 orientations on a single substrate is\ndemonstrated using VO2 grown on lithographically-patterned lines of Ti0.87O2\nand NbWO6 nanosheets investigated by electron backscatter diffraction. Finally,\nthe excellent suitability of these nanosheet-templated VO2 films for advanced\nlensless imaging of the metal-insulator transition using coherent soft X-rays\nis discussed."
    },
    {
        "anchor": "Bias Dependence and Electrical Breakdown of Small Diameter Single-Walled\n  Carbon Nanotubes: The electronic breakdown and the bias dependence of the conductance have been\ninvestigated for a large number of catalytic chemical vapor deposition (CCVD)\ngrown single-walled carbon nanotubes (SWCNTs) with very small diameters. The\nconvenient fabrication of thousands of properly contacted SWCNTs was possible\nby growth on electrode structures and subsequent electroless palladium\ndeposition. Almost all of the measured SWCNTs showed at least weak gate\ndependence at room temperature. Large differences in the conductance and\nbreakdown behavior have been found for \"normal\" semiconducting SWCNTs and small\nband-gap semiconducting (SGS) SWCNTs.",
        "positive": "First Principles Study of Work Functions of Double Wall Carbon Nanotubes: Using first-principles density functional calculations, we investigated work\nfunctions (WFs) of thin double-walled nanotubes (DWNTs) with outer tube\ndiameters ranging from 1nm to 1.5nm. The results indicate that work function\nchange within this diameter range can be up to 0.5 eV, even for DWNTs with same\nouter diameter. This is in contrast with single-walled nanotubes (SWNTs) which\nshow negligible WF change for diameters larger than 1nm. We explain the WF\nchange and related charge redistribution in DWNTs using charge equilibration\nmodel (CEM). The predicted work function variation of DWNTs indicates a\npotential difficulty in their nanoelectronic device applications."
    },
    {
        "anchor": "Tetragonal superstructure of the antiskyrmion hosting Heusler compound\n  Mn1.4PtSn: Skyrmions in non-centrosymmetric magnets are vortex-like spin arrangements,\nviewed as potential candidates for information storage devices. The crystal\nstructure and non-collinear magnetic structure together with magnetic and\nspin-orbit interactions define the symmetry of the Skyrmion structure. We\noutline the importance of these parameters in the Heusler compound Mn1.4PtSn\nwhich hosts antiskyrmions, a vortex-like spin texture related to skyrmions.1 We\novercome the challenge of growing large micro-twin-free single crystals of\nMn1.4PtSn which has proved to be the bottleneck for realizing bulk\nskyrmionic/antiskyrmionic states in a compound. The use of 5d-transition metal,\nplatinum, together with manganese as constituents in the Heusler compound such\nas Mn1.4PtSn is a precondition for the non-collinear magnetic structure. Due to\nthe tetragonal inverse Heusler structure, Mn1.4PtSn exhibits large\nmagneto-crystalline anisotropy and D2d symmetry, which are necessary for\nantiskyrmions. The superstructure in Mn1.4PtSn is induced by Mn-vacancies which\nenables a ferromagnetic exchange interaction to occur. Mn1.4PtSn, the first\nknown tetragonal Heusler superstructure compound, opens up a new research\ndirection for properties related to the superstructure in a family containing\nthousands of compounds.",
        "positive": "Coexistence of two types of short-range order in SiGeSn medium-entropy\n  alloys: Short-range chemical order (SRO) has been recently demonstrated to play a\ndecisive role in modulating a wide range of physical properties in\nmedium-entropy alloy (MEA) and high-entropy alloy (HEA). The enormous\nconfigurational space of these alloys implies multiple forms of SRO are likely\nto develop concurrently but such structural diversity has not been reported.\nHere we show, through extensive {\\em ab initio}-based sampling study, that\nSiGeSn medium-entropy alloys spontaneously develop two distinct forms of SRO.\nRemarkably, the two types of SROs, which carry different energies, distinct\ndegrees of local ordering, and dissimilar electronic structures, are found to\nco-exist in a wide range of compositions of SiGeSn alloys. The co-existence of\ntwo SROs is rationalized through their virtual degeneracy of thermodynamic\nstability, due to the subtle balance in the change of enthalpy and\nconfigurational entropy upon the transformation between the two SROs. Such\nco-existence of SROs thus suggests an inherent structural heterogeneity, a\ndiffuse electronic structure, and a new route for band engineering in SiGeSn\nMEA. More generally, our finding indicates the possible ubiquity of the\nco-existence of multiple forms of SRO in a broad range of MEAs and HEAs, which\nhas profound implications on their diverse physical properties."
    },
    {
        "anchor": "NMR study of small molecule adsorption in MOF-74-Mg: We calculate the carbon nuclear magnetic resonance (NMR) shielding for CO_2\nand the hydrogen shieldings for both H_2 and H_2O inside the metal organic\nframework MOF-74-Mg. Our ab initio calculations are at the density functional\ntheory level using the van der Waals including density functional vdW-DF. The\nshieldings are obtained while placing the small molecules throughout the\nstructure, including the calculated adsorption site for various loading\nscenarios. We then explore relationships between loading, rotational and\npositional characteristics, and the NMR shieldings for each adsorbate. Our NMR\ncalculations show a change in the shielding depending on adsorbate, position,\nand loading in a range that is experimentally observable. We further provide a\nsimple model for the energy and the NMR shieldings throughout the cavity of the\nMOF. By providing this mapping of shielding to position and loading for these\nadsorbates, we argue that NMR probes could be used to provide additional\ninformation about the position at which these small molecules bind within the\nMOF, as well as the loading of the adsorbed molecule.",
        "positive": "Stability of low-carrier-density topological-insulator Bi$_2$Se$_3$ thin\n  films and effect of capping layers: Although over the past number of years there have been many advances in the\nmaterials aspects of topological insulators (TI), one of the ongoing challenges\nwith these materials is the protection of them against aging. In particular,\nthe recent development of low-carrier-density bulk-insulating Bi$_2$Se$_3$ thin\nfilms and their sensitivity to air demands reliable capping layers to stabilize\ntheir electronic properties. Here, we study the stability of the\nlow-carrier-density Bi$_2$Se$_3$ thin films in air with and without various\ncapping layers using DC and THz probes. Without any capping layers, the carrier\ndensity increases by ~150% over a week and by ~280% over 9 months. In\nsitu-deposited Se and ex situ-deposited Poly(methyl methacrylate) (PMMA)\nsuppresses the aging effect to ~27% and ~88% respectively over 9 months. The\ncombination of effective capping layers and low-carrier-density TI films will\nopen up new opportunities in topological insulators."
    },
    {
        "anchor": "Fate of density functional theory in high-pressure solid hydrogen: This paper investigates some of the successes and failures of density\nfunctional theory in the study of high-pressure solid hydrogen at low\ntemperature. We calculate the phase diagram, metallization pressure, phonon\nspectrum, and proton zero-point energy using three popular exchange-correlation\nfunctionals: the local density approximation (LDA), the Perdew-Burke-Ernzerhof\n(PBE) generalized gradient approximation, and the semi-local\nBecke-Lee-Yang-Parr (BLYP) functional. We focus on the solid molecular\nP$6_3$/m, C2/c, Cmca-12, and Cmca structures in the pressure range from\n$100<P<500$ GPa over which phases I, II and III are observed experimentally. At\nthe static level of theory, in which proton zero-point energy is ignored, the\nLDA, PBE and BLYP functionals give very different structural transition and\nmetallization pressures, with the BLYP phase diagram in better agreement with\nexperiment. Nevertheless, all three functionals provide qualitatively the same\ninformation about the band gaps of the four structures and the phase\ntransitions between them. Going beyond the static level, we find that the\nfrequencies of the vibron modes observed above 3000 cm$^{-1}$ depend strongly\non the choice of exchange-correlation functional, although the low-frequency\npart of the phonon spectrum is little affected. The largest and smallest values\nof the proton zero-point energy, obtained using the BLYP and LDA functionals,\nrespectively, differ by more than 10 meV/proton. Including the proton\nzero-point energy calculated from the phonon spectrum within the harmonic\napproximation improves the agreement of the BLYP and PBE phase diagrams with\nexperiment. Taken as a whole, our results demonstrate the inadequacy of\nmean-field-like density functional calculations of solid molecular hydrogen in\nphases I, II and III and emphasize the need for more sophisticated methods.",
        "positive": "Caloric effects around phase transitions in magnetic materials described\n  by ab initio theory: The electronic glue and fluctuating local moments: We describe magneto-, baro- and elastocaloric effects (MCEs, BCEs and eCEs)\nin materials which possess both discontinuous (first-order) and continuous\n(second-order) magnetic phase transitions. Our ab initio theory of the\ninteracting electrons of materials in terms of disordered local moments (DLMs)\nhas produced explicit mechanisms for the drivers of these transitions and here\nwe study associated caloric effects in three case studies where both types of\ntransition are evident. Our earlier work had described FeRh's magnetic phase\ndiagram and large MCE. Here we present calculations of its substantial BCE and\neCE. We describe the MCE of dysprosium and find very good agreement with\nexperimental values for isothermal entropy ($\\Delta S_{iso}$) and adiabatic\ntemperature ($\\Delta T_{ad}$) changes over a large temperature span and\ndifferent applied magnetic field values. We examine the conditions for optimal\nvalues of both $\\Delta S_{iso}$ and $\\Delta T_{ad}$ that comply with a\nClausius-Clapeyron analysis, which we use to propose a promising elastocaloric\ncooling cycle arising from the unusual dependence of the entropy on temperature\nand biaxial strain found in our third case study - the Mn$_3$GaN\nantiperovskite. We explain how both $\\Delta S_{iso}$ and $\\Delta T_{ad}$ can be\nkept large by exploiting the complex tensile strain-temperature magnetic phase\ndiagram which we had earlier predicted for this material and also propose that\nhysteresis effects will be absent from half the caloric cycle. This rich and\ncomplex behavior stems from the frustrated nature of the interactions among the\nMn local moments."
    },
    {
        "anchor": "Control over epitaxy and the role of the InAs/Al interface in hybrid\n  two-dimensional electron gas systems: In-situ synthesised semiconductor/superconductor hybrid structures became an\nimportant material platform in condensed matter physics. Their development\nenabled a plethora of novel quantum transport experiments with focus on Andreev\nand Majorana physics. The combination of InAs and Al has become the workhorse\nmaterial and has been successfully implemented in the form of one-dimensional\nstructures and two-dimensional electron gases. In contrast to the\nwell-developed semiconductor parts of the hybrid materials, the direct effect\nof the crystal nanotexture of Al films on the electron transport still remains\nunclear. This is mainly due to the complex epitaxial relation between Al and\nthe semiconductor. We present a study of Al films on shallow InAs\ntwo-dimensional electron gas systems grown by molecular beam epitaxy, with\nfocus on control of the Al crystal structure. We identify the dominant grain\ntypes present in our Al films and show that the formation of grain boundaries\ncan be significantly reduced by controlled roughening of the epitaxial\ninterface. Finally, we demonstrate that the implemented roughening does not\nnegatively impact either the electron mobility of the two-dimensional electron\ngas or the basic superconducting properties of the proximitized system.",
        "positive": "Carrier and Spin Coherent Dynamics in Strained Germanium-Tin\n  Semiconductor on Silicon: Germanium-Tin is emerging as a material exhibiting excellent photonic\nproperties. Here we demonstrate optical initialization and readout of spins in\nthis intriguing group IV semiconductor alloy and report on spin quantum beats\nbetween Zeeman-split levels under an external magnetic field. Our optical\nexperiments reveal robust spin orientation in a wide temperature range and a\npersistent spin lifetime that approaches the ns regime at room temperature.\nBesides important insights into nonradiative recombination pathways, our\nfindings disclose a rich spin physics in novel epitaxial structures directly\ngrown on a conventional Si substrate. This introduces a viable route towards\nthe synergic enrichment of the group IV semiconductor toolbox with advanced\nspintronics and photonic capabilities."
    },
    {
        "anchor": "Ferromagnetic Clusters in the Brownmillerite Bilayered Compounds\n  Ca2.5-xLaxSr0.5GaMn2O8: An Approach to Achieve Layered Spintronics Materials: We report the effect of La-substitution on the magnetic and magnetotransport\nproperties of Brownmillerite-like bilayered compounds Ca2.5-xLaxSr0.5GaMn2O8 (x\n= 0, 0.05, 0.075, and 0.1) by using dc-magnetization, resistivity and\nmagnetoresistance techniques. The Rietveld analysis of the room temperature\nx-ray diffraction patterns confirms no observable change of average crystal\nstructure with the La-substitution. Both magnetic and magnetotransport\nproperties are found to be very sensitive to the La-substitution.\nInterestingly, the La-substituted compounds show ferromagnetic-like behavior\n(due to the occurrence of a double exchange mechanism) whereas, the parent\ncompound is an antiferromagnet (TN 150 K). All compounds show an insulating\nbehavior, in the measured temperature range of 100 - 300 K, with an overall\ndecrease in the resistivity with the substitution. A higher value of\nmagnetoresistance has been successfully achieved by the La-substitution. We\nhave proposed an electronic phase separation model, considering the formation\nof ferromagnetic clusters in the antiferromagnetic matrix, to interpret the\nobserved magnetization and magnetotransport results for the La-substituted\nsamples. The present study demonstrates an approach to achieve new functional\nmaterials, based on naturally occurring layered system like\nCa2.5-xLaxSr0.5GaMn2O8, for possible spintronics applications.",
        "positive": "Ultrafast dynamics of coherent phonons and phonon-polaritons in lithium\n  niobate crystals: This study investigates the ultrafast dynamics of coherent phonons and\nphonon-polaritons in lithium niobate (LiNbO$_{3}$) crystals using reflective\npump-probe spectroscopy with 25-fs time resolution. In addition to several\ncoherent optical phonon modes, the electro-optic sampling measurements explored\nthe coexistence of phonon-polariton E-modes near 3.8 and 14.9 THz, which agrees\nconsiderably with the theoretical phonon-polariton dispersion curves. We also\ndiscovered that a time lag ($\\Delta$t $\\approx$ 0.2 ps) between the coherent\noptical phonon and phonon-polariton originates from the coupling time for\npropagating phonon-polariton. Our findings provide a possible application of\nLiNbO$_{3}$ for ultrafast electro-optic phonon modulators with bandwidths\ngreater than 10 THz."
    },
    {
        "anchor": "Scratch-induced surface microstructures on the deformed surface of\n  Al-Cu-Fe icosahedral quasicrystals: Scanning electron microscopy (SEM) and transmission electron microscopy (TEM)\ninvestigations of sintered Al-Cu-Fe icosahedral quasicrystal (IQC) have been\ncarried out to understand the origin of some ductility previously noticed\nwithin tracks produced by standard tribological scratch tests. Transformation\nof the icosahedral phase to a modulated structure is shown and a transformation\nof the IQC to a bcc phase has been found beneath the tracks. Twins and\ndislocations have also been observed.",
        "positive": "Short-range ordering in the Ni-Mn-Si based Laves phase\n  Mn(Ni$_{0.6}$Si$_{0.4})_2$: We present the structural ordering and the associated physical behavior of a\nNi-Mn-Si Laves phase, Mn(Ni$_{0.6}$Si$_{0.4})_2$. The high-resolution\ntransmission electron microscopy and electron energy loss spectroscopy analysis\nwere performed to resolve a distinct atomic ordering of the system. The study\ndetermined the origin of the short-range ordering to be the unique arrangement\nbetween Ni and Si atoms. The study also presents the atomic resolution mapping\nof the Si atoms which has never been reported by any previous studies. With\nfurther electrical conductivity measurement, we find one of the consequences of\nthe unique ordering reflected in a semiconducting like temperature dependence\nof the compound."
    },
    {
        "anchor": "A Coupled Equations Model for Epitaxial Growth on Textured Surfaces: We have developed a continuum model that explains the complex surface shapes\nobserved in epitaxial regrowth on micron scale gratings. This model describes\nthe dependence of the surface morphology on film thickness and growth\ntemperature in terms of a few simple atomic scale processes including adatom\ndiffusion, step-edge attachment and detachment, and a net downhill migration of\nsurface adatoms. The continuum model reduces to the linear part of the\nKardar-Parisi-Zhang equation with a flux dependent smoothing coefficient in the\nlong wavelength limit.",
        "positive": "Epitaxy of new layered materials: 2D chalcogenides and challenges of\n  weak van der Waals interactions: The application of new materials in nanotechnology opens new perspectives and\nenables ground-breaking innovations. Two-dimensional van der Waals materials\nand more specific, 2D chalcogenides are a promising class of new materials\nawaiting their usage in the semiconductor industry. However, the integration of\nvan der Waals materials relying on industry-compatible manufacturing processes\nis still a major challenge. This is currently restricting the application of\nthese new materials to the research laboratories environment only. The\nlarge-area and single-crystalline growth of van der Waals materials is one of\nthe most important requirements to meet the challenging demands implied by the\nsemiconductor industry. This review contributes to a more generalized\nunderstanding on the integration of van der Waals materials - and in more\nspecific 2D chalcogenides - through the growth process of epitaxy. This, can\npursue further the aspiration of large-area, single-crystalline and defect-free\nepitaxial integration of (quasi) van der Waals homo- and heterostructures into\nthe great world of the semiconductor industry."
    },
    {
        "anchor": "Examples for the improvements in AES Depth Profiling of Multilayer Thin\n  Film Systems by Application of Factor Analysis Data Evaluation: Factor Analysis has proved to be a powerful tool for the full exploitation of\nthe chemical information included in the peak shapes and peak positions of\nspectra measured by AES depth profiling. Due to its ability to extract the\nnumber of independent chemical components, their spectra and their depth\ndistributions, its information content exceeds the one of the usual\npeak-to-peak height evaluation of AES depth profile data. Using modern software\nwith a graphically interactive user interface the analyst is put into a\nposition, where he can work with Factor Analysis on a physically intuitive\nlevel despite of all the matrix algebra mathematics which it is based upon. The\nprogress brought about by Factor Analysis to AES depth profiles of thin films\nis demonstrated by the analysis of two thin film systems. The first one is a\nPt/Ti metallisation used as bottom electrode for ferroelectric thin films, the\nsecond one is multilayer system where a Ti silicide formation of burried Ti/Si\nbilayers has been induced. Both examples show that Factor Analysis evaluation\nof AES depth profile data is capable to give access to stoichiometry\ninformation and to reveal interfacial layer phases, information which is hardly\nobtained from the conventional peak-to-peak height data evaluation.",
        "positive": "Lattice stability and high pressure melting mechanism of dense hydrogen\n  up to 1.5 TPa: Lattice stability and metastability, as well as melting, are important\nfeatures of the physics and chemistry of dense hydrogen. Using ab initio\nmolecular dynamics (AIMD), the classical superheating limit and melting line of\nmetallic hydrogen are investigated up to 1.5 TPa. The computations show that\nthe classical superheating degree is about 100 K, and the classical melting\ncurve becomes flat at a level of 350 K when beyond 500 GPa. This information\nallows us to estimate the well depth and the potential barriers that must be\novercome when the crystal melts. Inclusion of nuclear quantum effects (NQE)\nusing path integral molecular dynamics (PIMD) predicts that both superheating\nlimit and melting temperature are lowered to below room temperature, but the\nlatter never reach absolute zero. Detailed analysis indicates that the melting\nis thermally activated, rather than driven by pure zero-point motion (ZPM).\nThis argument was further supported by extensive PIMD simulations,\ndemonstrating the stability of Fddd structure against liquefaction at low\ntemperatures."
    },
    {
        "anchor": "Shallow Valence Band of Rutile GeO$_2$ and P-type Doping: GeO$_2$ has an $\\alpha$-quartz-type crystal structure with a very wide\nfundamental band gap of 6.6 eV and is a good insulator. Here we find that the\nstable rutile-GeO$_2$ polymorph with a 4.6 eV band gap has a surprisingly low\n$\\sim$6.8 eV ionization potential, as predicted from the band alignment using\nfirst-principles calculations. Because of the short O$-$O distances in the\nrutile structure containing cations of small effective ionic radii such as\nGe$^{4+}$, the antibonding interaction between O 2p orbitals raises the valence\nband maximum energy level to an extent that hole doping appears feasible.\nExperimentally, we report the flux growth of $1.5 \\times 1.0 \\times 0.8$ mm$^3$\nlarge rutile GeO$_2$ single crystals and confirm the thermal stability for\ntemperatures up to $1021 \\pm 10~^\\circ$C. X-ray fluorescence spectroscopy shows\nthe inclusion of unintentional Mo impurities from the Li$_2$O$-$MoO$_3$ flux,\nas well as the solubility of Ga in the r-GeO$_2$ lattice as a prospective\nacceptor dopant. The resistance of the Ga- and Mo-codoped r-GeO$_2$ single\ncrystals is very high at room temperature, but it decreases by 2-3 orders of\nmagnitude upon heating to 300 $^\\circ$C, which is attributed to\nthermally-activated p-type conduction.",
        "positive": "Size-dependent phase transitions in MoS2 nanoparticles controlled by a\n  metal substrate: Nanomaterials based on MoS2 are remarkably versatile; MoS2 nanoparticles are\nproven catalysts for processes such as hydrodesulphurization and the hydrogen\nevolution reaction, and transition metal dichalcogenides in general have\nrecently emerged as novel 2D components for nanoscale electronics and\noptoelectronics. The properties of such materials are intimately related to\ntheir structure and dimensionality. For example, only the edges exposed by MoS2\nnanoparticles (NPs) are catalytically active, and extended MoS2 systems show\ndifferent character (direct or indirect gap semiconducting, or metallic)\ndepending on their thickness and crystallographic phase. In this work, we show\nhow particle size and interaction with a metal surface affect the stability and\nproperties of different MoS2 NPs and the resulting phase diagrams. By means of\ncalculations based on the Density Functional Theory (DFT), we address how\nsupport interactions affect MoS2 nanoparticles of varying size, composition,\nand structure. We demonstrate that interaction with Au modifies the relative\nstability of the different nanoparticle types so that edge terminations and\ncrystallographic phases that are metastable for free-standing nanoparticles and\nmonolayers are expressed in the supported system. These support-effects are\nstrongly size-dependent due to the mismatch between Au and MoS2 lattices, which\nexplains experimentally observed transitions in the structural phases for\nsupported MoS2 NPs. Accounting for vdW interactions and the contraction of the\nAu(111) surface underneath the MoS2 is further found to be necessary for\nquantitatively reproducing experimental results. This work demonstrates how the\nproperties of nanostructured MoS2 and similar layered systems can be modified\nby the choice of supporting metal."
    },
    {
        "anchor": "Characterization of the Magnetocaloric Effect in RMn6Sn6 including High\n  Entropy Alloys: We present a comprehensive study of the magnetocaloric effect (MCE) in a\nfamily of kagome magnets with formula RMn6Sn6 (R=Tb, Ho, Er, and Lu). These\nmaterials have a small rare-earth content and tunable magnetic ordering, hence\nthey provide a venue to study the fundamentals of the MCE. We examine the\neffect of different types of order (ferrimagnetic and antiferromagnetic) and\nthe presence of a metamagnetic transition on the MCE. We extend the study to\nhigh-entropy rare-earth alloys of the family. Our results suggest several\nguidelines for enhancing the MCE in tunable magnetic materials with a small\nrare-earth content.",
        "positive": "The role of screening in the density functional applied on transition\n  metal defects in semiconductors: We study selected transition metal related point defects in silicon and\nsilicon carbide semiconductors by a range separated hybrid density functional\n(HSE06). We find that HSE06 does not fulfill the generalized Koopmans' Theorem\nfor every defect which is due to the self-interaction error in the functional\nin such cases. Restoring the so-called generalized Koopmans' Condition with a\nsimple correction in the functional can eliminate this error, and brings the\ncalculated charge transition levels remarkably close to the experimental data\nas well as to the calculated quasi-particle levels from many-body perturbation\ntheory."
    },
    {
        "anchor": "Dielectric relaxation and polar phonon softening in relaxor\n  ferroelectric PbMg_(1/3)Ta_(2/3)O_3: Relaxor ferroelectric PbMg_1/3Ta_2/3O_3 ceramics and thin films were\ninvestigated by means of broad-band dielectric, time-domain terahertz (THz) and\nFourier-transform infrared (IR) spectroscopy in the frequency range 100 Hz - 90\nTHz at temperatures 100 - 490 K, the THz and IR spectra were studied from 20 to\n900K. Diffused and strongly temperature dependent peak in the complex\npermittivity is caused by a dielectric relaxation due to the dynamics of polar\nclusters. The relaxation appears below Burns temperature T_d in the THz range,\nslows down on cooling through the microwave and MHz range and anomalously\nbroadens. The shortest and longest relaxation times of the distribution of\nrelaxation times follow Arrhenius and Vogel-Fulcher law, respectively. The\ndegree of B-site order has only a small influence on the parameters of the\ndielectric relaxation and almost no influence on the phonon parameters. Below\nT_m ~ 180K, the distribution of relaxation frequencies becomes broader than our\nexperimental spectral range and frequency independent dielectric losses develop\nbelow 100 GHz in the spectra. Although the macroscopic crystal structure is\ncubic, IR spectra give evidence about the lower local symmetry which can be\nassigned to the presence of polar clusters below T_d. Infrared spectra above\nT_d still reveal more modes than predicted by selection rules in the\nparaelectric phase of the Fm-3m space group so that we suggest selection rules\nwhich take into account chemical inhomogeneity in the beta''-perovskite\nsublattice.",
        "positive": "Atomic Layer Deposition-Based Synthesis of Photoactive TiO2 Nanoparticle\n  Chains by Using Carbon Nanotubes as Sacrificial Templates: Highly ordered and self supported anatase TiO2 nanoparticle chains were\nfabricated by calcining conformally TiO2 coated multi-walled carbon nanotubes\n(MWCNTs). During annealing, the thin tubular TiO2 coating that was deposited\nonto the MWCNTs by atomic layer deposition (ALD) was transformed into chains of\nTiO2 nanoparticles (~12 nm diameter) with an ultrahigh surface area (137 cm2\nper cm2 of substrate), while at the same time the carbon from the MWCNTs was\nremoved. Photocatalytic tests on the degradation of acetaldehyde proved that\nthese forests of TiO2 nanoparticle chains are highly photo active under UV\nlight because of their well crystallized anatase phase."
    },
    {
        "anchor": "Insights on the variability of Cu filament formation in the SiO2\n  electrolyte of quantized-conductance conductive bridge random access memory\n  devices: Conductive bridge random access memory devices such as Cu/SiO2/W are\npromising candidates for applications in neuromorphic computing due to their\nfast, low-voltage switching, multiple-conductance states, scalability, low\noff-current, and full compatibility with advanced Si CMOS technologies. The\nconductance states, which can be quantized, originate from the formation of a\nCu filament in the SiO2 electrolyte due to cation-migration-based\nelectrochemical processes. A major challenge related to the filamentary nature\nis the strong variability of the voltage required to switch the device to its\nconducting state. Here, based on a statistical analysis of more than hundred\nfifty Cu/SiO2/W devices, we point to the key role of the activation energy\ndistribution for copper ion diffusion in the amorphous SiO2. The cycle-to-cycle\nvariability is modeled well when considering the theoretical energy landscape\nfor Cu diffusion paths to grow the filament. Perspectives of this work point to\ndeveloping strategies to narrow the distribution of activation energies in\namorphous SiO2.",
        "positive": "Variation in electron work function with temperature and its effect on\n  the Young's modulus of metals: Properties of metals are fundamentally determined by their electron behavior,\nwhich is largely reflected by the electron work function ($\\varphi $). Recent\nstudies have demonstrated that many properties of metallic materials are\ndirectly related to $\\varphi $, which may provide a simple but fundamental\nparameter for material design. Since material properties are affected by\ntemperature, in this article a simple model is proposed to correlate the work\nfunction with temperature, expressed as $\\varphi (T)=\\varphi_{0} -\\gamma\n\\frac{(k_{B} T)^{2}}{\\varphi_{0}} $, where $\\gamma $ varies with the crystal\nstructure. This $\\varphi $-T relationship helps determine and understand the\ndependence of metal properties on temperature on a feasible electronic base. As\na sample application, the established relationship is applied to determine the\ndependence of Young's modulus of metals on temperature. The proposed\nrelationship is consistent with experimental observations."
    },
    {
        "anchor": "Growth of three-dimensional structures by atomic deposition on surfaces\n  containing defects : simulations and theory: We perform a comprehensive study of the formation of three dimensional\n(pyramidal) structures in a large range of conditions, including the possible\nevaporation of adatoms from the surface and the presence of surface defects. We\ncompare our computer simulations to theoretical calculations of the growth and\nfind good agreement between them. This work clarifies precedent studies of\nthree dimensional growth and predicts the island size distributions obtained in\nthe different regimes. Finally, we show how our analysis can be used to\ninterpret experimental data.",
        "positive": "Oxidation of graphite surface: the role of water: Based on density functional calculations, we demonstrate a significant\ndifference in oxidation patterns between graphene and graphite and the\nformation of defects after oxidation. Step-by-step modeling demonstrates that\noxidation of 80% of the graphite surface is favorable. Oxidation above half of\nthe graphite surface significantly decreases the energy costs of vacancy\nformation with CO2 production. The presence of water is crucial in the\ntransformation of epoxy groups to hydroxyl, the intercalation with further\nbundle and exfoliation. In water-rich conditions, water intercalates graphite\nat the initial stages of oxidation and oxidation, which is similar to the\noxidation process of free-standing graphene; in contrast, in water-free\nconditions, large molecules intercalate graphite only after oxidation occurs on\nmore than half of the surface."
    },
    {
        "anchor": "Visualizing the mixed bonding properties of liquid boron with high\n  resolution Compton scattering: Bonding characteristics of liquid boron at 2500K are studied by using high\nresolution Compton scattering. An excellent agreement is found between the\nmeasurements and the corresponding Car-Parinello molecular dynamics\nsimulations. Covalent bond pairs are clearly shown to dominate in liquid boron\nalong with the coexistence of diffuse pairs. Our study reveals the complex\nbonding pattern of liquid boron, and gives insight into the unusual properties\nof this high temperature liquid.",
        "positive": "Control of magnetization dynamics by substrate orientation in YIG thin\n  films: Yttrium Iron Garnet (YIG) and bismuth (Bi) substituted YIG (Bi0.1Y2.9Fe5O12,\nBYG) films are grown in-situ on single crystalline Gadolinium Gallium Garnet\n(GGG) substrates [with (100) and (111) orientations] using pulsed laser\ndeposition (PLD) technique. As the orientation of the Bi-YIG film changes from\n(100) to (111), the lattice constant is enhanced from 12.384 {\\AA} to 12.401\n{\\AA} due to orientation dependent distribution of Bi3+ ions at dodecahedral\nsites in the lattice cell. Atomic force microscopy (AFM) images show smooth\nfilm surfaces with roughness 0.308 nm in Bi-YIG (111). The change in substrate\norientation leads to the modification of Gilbert damping which, in turn, gives\nrise to the enhancement of ferromagnetic resonance (FMR) line width. The best\nvalues of Gilbert damping are found to be (0.54)*10-4, for YIG (100) and\n(6.27)*10-4, for Bi-YIG (111) oriented films. Angle variation measurements of\nthe Hr are also performed, that shows a four-fold symmetry for the resonance\nfield in the (100) grown film. In addition, the value of effective\nmagnetization (4{\\pi}Meff) and extrinsic linewidth ({\\Delta}H0) are observed to\nbe dependent on substrate orientation. Hence PLD growth can assist\nsingle-crystalline YIG and BYG films with a perfect interface that can be used\nfor spintronics and related device applications."
    },
    {
        "anchor": "Ferromagnetic Wires Composite Media with Tunable Scattering Spectra at\n  Microwaves: We demonstrate composite media with ferromagnetic wires that exhibit a\nfrequency region at the microwave regime with scattering spectra strongly\ndependent on an external magnetic field or stress. These tunable composite\nmaterials have recently been proposed theoretically; however, no direct\nexperimental verification has been reported. We used composite materials with\npredominantly oriented CoFeCrSiB glass-coated amorphous wires having large\nmagnetoimpedance at GHz frequencies. The free space measurements of reflection\nand transmission coefficients were conducted in the frequency range 1-8 GHz in\nthe presence of an external static magnetic field or stress applied to the\nwhole sample. In general, the transmission spectra show greater changes in the\nrange of 10dB for a relatively small magnetic field of few Oe or stress of 0.1\nMPa. The obtained results are quantitatively consistent with the analytical\nexpressions predicted by the effective medium arguments. The incident\nelectromagnetic wave induces an electrical dipole moment in each wire, the\naggregate of which forms the effective dipole response of the whole composite\nstructure in the radiative near or far field region. The field and stress\ndependences of the effective response arise from a field or tensile stress\nsensitivity of the ac surface impedance of a ferromagnetic wire. In the\nvicinity of the antenna resonance the variations in the magneto-impedance of\nthe wire inclusions result in large changes of the total effective response. A\nnumber of applications of proposed materials is discussed including the field\ntunable microwave surfaces and the self-sensing media for the remote\nnon-destructive evaluation of structural materials.",
        "positive": "A multilevel nonvolatile magnetoelectric memory based on memtranstor: The coexistence and coupling between magnetization and electric polarization\nin multiferroic materials provide extra degrees of freedom for creating\nnext-generation memory devices. A variety of concepts of multiferroic or\nmagnetoelectric memories have been proposed and explored in the past decade.\nHere we propose a new principle to realize a multilevel nonvolatile memory\nbased on the multiple states of the magnetoelectric coefficient ({\\alpha}) of\nmultiferroics. Because the states of {\\alpha} depends on the relative\norientation between magnetization and polarization, one can reach different\nlevels of {\\alpha} by controlling the ratio of up and down ferroelectric\ndomains with external electric fields. Our experiments in a device made of the\nPMN-PT/Terfenol-D multiferroic heterostructure confirm that the states of\n{\\alpha} can be well controlled between positive and negative by applying\nselective electric fields. Consequently, two-level, four-level, and eight-level\nnonvolatile memory devices are demonstrated at room temperature. This kind of\nmultilevel magnetoelectric memory retains all the advantages of ferroelectric\nrandom access memory but overcomes the drawback of destructive reading of\npolarization. In contrast, the reading of {\\alpha} is nondestructive and highly\nefficient in a parallel way, with an independent reading coil shared by all the\nmemory cells."
    },
    {
        "anchor": "Heating Isotopically Labelled Bernal Stacked Graphene: a Raman\n  Spectroscopy Study: One of the greatest issues of nanoelectronics today is how to control the\nheating of the components. Graphene is a promising material in this area and it\nis essential to study its thermal properties. Here, the effect of heating a\nbilayer structure was investigated using in situ Raman spectroscopy. In order\nto observe the effects on each individual layer, an isotopically labelled\nbilayer graphene was synthesized where the two layers are composed of different\ncarbon isotopes. Therefore, the frequency of the phonons in the Raman spectra\nis shifted in relation to each other. This technique was used to investigate\nthe influence of different stacking order. It was found that in bilayer\ngraphene grown by chemical vapor deposition (CVD) the two layers behave very\nsimilarly, for both Bernal stacking and randomly oriented structures, while for\ntransferred samples the layers act more independently. This highlights a\nsignificant dependence on sample preparation procedure.",
        "positive": "Tin-selenium compounds at ambient and high pressures: SnxSey crystalline compounds consisting of Sn and Se atoms of varying\ncomposition are systematically investigated at pressures from 0 to 100 GPa\nusing the first-principles evolutionary crystal structure search method based\non density functional theory (DFT). All known experimental phases of SnSe and\nSnSe2 are found without any prior input. A second order polymorphic phase\ntransition from SnSe-Pnma phase to SnSe-Cmcm phase is predicted at 2.5 GPa.\nInitially being semiconducting, this phase becomes metallic at 7.3 GPa. Upon\nfurther increase of pressure up to 36.6 GPa, SnSe-Cmcm phase is transformed to\nCsCl-type SnSe-Pm3m phase, which remains stable at even higher pressures. A\nmetallic compound with different stoichiometry, Sn3Se4-I43d, is found to be\nthermodynamically stable from 18 GPa to 70 GPa. Known semiconductor tin\ndiselenide SnSe2-P3m1 phase is found to be thermodynamically stable from\nambient pressure up to 18 GPa. Initially being semiconducting, it experiences\nmetalization at pressures above 8 GPa."
    },
    {
        "anchor": "A critical study of the elastic properties and stability of Heusler\n  compounds: Phase change and tetragonal $X_{2}YZ$ compounds: In the present work, the elastic constants and derived properties of\ntetragonal and cubic Heusler compounds were calculated using the high accuracy\nof the full-potential linearized augmented plane wave (FPLAPW). To find the\ncriteria required for an accurate calculation, the consequences of increasing\nthe numbers of $k$-points and plane waves on the convergence of the calculated\nelastic constants were explored. Once accurate elastic constants were\ncalculated, elastic anisotropies, sound velocities, Debye temperatures,\nmalleability, and other measurable physical properties were determined for the\nstudied systems. The elastic properties suggested metallic bonding with\nintermediate malleability, between brittle and ductile, for the studied Heusler\ncompounds. To address the effect of off-stoichiometry on the mechanical\nproperties, the virtual crystal approximation (VCA) was used to calculate the\nelastic constants. The results indicated that an extreme correlation exists\nbetween the anisotropy ratio and the stoichiometry of the Heusler compounds,\nespecially in the case of Ni$_{2}$MnGa.",
        "positive": "Hard X-rays as pump and probe of atomic motion in oxide glasses: Nowadays powerful X-ray sources like synchrotrons and free-electron lasers\nare considered as ultimate tools for probing microscopic properties in\nmaterials. However, the correct interpretation of such experiments requires a\ngood understanding on how the beam affects the properties of the sample,\nknowledge that is currently lacking for intense X-rays. Here we use X-ray\nphoton correlation spectroscopy to probe static and dynamic properties of oxide\nand metallic glasses. We find that although the structure does not depend on\nthe flux, strong fluxes do induce a non-trivial microscopic motion in oxide\nglasses, whereas no such dependence is found for metallic glasses. These\nresults show that high fluxes can alter dynamical properties in hard materials,\nan effect that needs to be considered in the analysis of X-ray data but which\nalso gives novel possibilities to study materials properties since the beam can\nnot only be used to probe the dynamics but also to pump it."
    },
    {
        "anchor": "NMR shifts for polycyclic aromatic hydrocarbons from first-principles: We present first-principles, density-functional theory calculations of the\nNMR chemical shifts for polycyclic aromatic hydrocarbons, starting with benzene\nand increasing sizes up to the one- and two-dimensional infinite limits of\ngraphene ribbons and sheets. Our calculations are performed using a combination\nof the recently developed theory of orbital magnetization in solids, and a\nnovel approach to NMR calculations where chemical shifts are obtained from the\nderivative of the orbital magnetization with respect to a microscopic,\nlocalized magnetic dipole. Using these methods we study on equal footing the\n$^1$H and $^{13}$C shifts in benzene, pyrene, coronene, in naphthalene,\nanthracene, naphthacene, and pentacene, and finally in graphene, graphite, and\nan infinite graphene ribbon. Our results show very good agreement with\nexperiments and allow us to characterize the trends for the chemical shifts as\na function of system size.",
        "positive": "BiTeCl and BiTeBr: a comparative high-pressure optical study: We here report a detailed high-pressure infrared transmission study of BiTeCl\nand BiTeBr. We follow the evolution of two band transitions: the optical\nexcitation $\\beta$ between two Rashba-split conduction bands, and the\nabsorption $\\gamma$ across the band gap. In the low pressure range, $p< 4$~GPa,\nfor both compounds $\\beta$ is approximately constant with pressure and $\\gamma$\ndecreases, in agreement with band structure calculations. In BiTeCl, a clear\npressure-induced phase transition at 6~GPa leads to a different ground state.\nFor BiTeBr, the pressure evolution is more subtle, and we discuss the\npossibility of closing and reopening of the band gap. Our data is consistent\nwith a Weyl phase in BiTeBr at 5$-$6~GPa, followed by the onset of a structural\nphase transition at 7~GPa."
    },
    {
        "anchor": "Giant room temperature anomalous Hall effect and magnetically tuned\n  topology in the ferromagnetic Weyl semimetal Co2MnAl: Weyl semimetals (WSM) have been extensively studied due to their exotic\nproperties such as topological surface states and anomalous transport\nphenomena. Their band structure topology is usually predetermined by material\nparameters and can hardly be manipulated once the material is formed. Their\nunique transport properties appear usually at very low temperature, which sets\nchallenges for practical device applications. In this work, we demonstrate a\nway to modify the band topology via a weak magnetic field in a ferromagnetic\ntopological semimetal, Co2MnAl, at room temperature. We observe a tunable,\ngiant anomalous Hall effect, which is induced by the transition between Weyl\npoints and nodal rings as rotating the magnetization axis. The anomalous Hall\nconductivity is as large as that of a 3D quantum anomalous Hall effect (QAHE),\nwith the Hall angle reaching a record value (21%) at the room temperature among\nmagnetic conductors. Furthermore, we propose a material recipe to generate the\ngiant anomalous Hall effect by gaping nodal rings without requiring the\nexistence of Weyl points. Our work reveals an ideal intrinsically magnetic\nplatform to explore the interplay between magnetic dynamics and topological\nphysics for the development of a new generation of spintronic devices.",
        "positive": "Out-of-plane nesting driven spin spiral in ultrathin Fe/Cu(001) films: Epitaxial ultrathin Fe films on fcc Cu(001) exhibit a spin spiral (SS), in\ncontrast to the ferromagnetism of bulk bcc Fe. We study the in-plane and\nout-of-plane Fermi surfaces (FSs) of the SS in 8 monolayer Fe/Cu(001) films\nusing energy dependent soft x-ray momentum-resolved photoemission spectroscopy.\nWe show that the SS originates in nested regions confined to out-of-plane FSs,\nwhich are drastically modified compared to in-plane FSs. From precise\nreciprocal space maps in successive zones, we obtain the associated real space\ncompressive strain of 1.5+-0.5% along c-axis. An autocorrelation analysis\nquantifies the incommensurate ordering vector q=(2pi/a)(0,0,~0.86), favoring a\nSS and consistent with magneto-optic Kerr effect experiments. The results\nreveal the importance of in-plane and out-of-plane FS mapping for ultrathin\nfilms."
    },
    {
        "anchor": "Roadmap for Emerging Materials for Spintronic Device Applications: The Technical Committee of the IEEE Magnetics Society has selected 7 research\ntopics to develop their roadmaps, where major developments should be listed\nalongside expected timelines; (i) hard disk drives, (ii) magnetic random access\nmemories, (iii) domain-wall devices, (iv) permanent magnets, (v) sensors and\nactuators, (vi) magnetic materials and (vii) organic devices. Among them,\nmagnetic materials for spintronic devices have been surveyed as the first\nexercise. In this roadmap exercise, we have targeted magnetic tunnel and\nspin-valve junctions as spintronic devices. These can be used for example as a\ncell for a magnetic random access memory and spin-torque oscillator in their\nvertical form as well as a spin transistor and a spin Hall device in their\nlateral form. In these devices, the critical role of magnetic materials is to\ninject spin-polarised electrons efficiently into a non-magnet. We have\naccordingly identified 2 key properties to be achieved by developing new\nmagnetic materials for future spintronic devices: (1) Half-metallicity at room\ntemperature (RT); (2) Perpendicular anisotropy in nano-scale devices at RT. For\nthe first property, 5 major magnetic materials are selected for their\nevaluation for future magnetic/spintronic device applications: Heusler alloys,\nferrites, rutiles, perovskites and dilute magnetic semiconductors. These alloys\nhave been reported or predicted to be half-metallic ferromagnets at RT. They\npossess a bandgap at the Fermi level EF only for its minority spins, achieving\n100% spin polarisation at EF. We have also evaluated L10-alloys and\nD022-Mn-alloys for the development of a perpendicularly anisotropic ferromagnet\nwith large spin polarisation. We have listed several key milestones for each\nmaterial on their functionality improvements, property achievements, device\nimplementations and interdisciplinary applications within 35 years time scale.",
        "positive": "Negative oxygen vacancies in HfO$_2$ as charge traps in high-k stacks: We calculated the optical excitation and thermal ionization energies of\noxygen vacancies in m-HfO$_2$ using atomic basis sets, a non-local density\nfunctional and periodic supercell. The thermal ionization energies of\nnegatively charged V$^-$ and V$^{2-}$ centres are consistent with values\nobtained by the electrical measurements. The results suggest that negative\noxygen vacancies are the likely candidates for intrinsic electron traps in the\nhafnum-based gate stack devices."
    },
    {
        "anchor": "A theoretical study of the hydrogen-storage potential of (H_2)_4CH_4 in\n  metal organic framework materials and carbon nanotubes: The hydrogen-methane compound (H_2)_4CH_4---or for short H4M---is one of the\nmost promising hydrogen-storage materials. This van der Waals compound is\nextremely rich in molecular hydrogen: 33.3 mass%, not including the hydrogen\nbound in CH_4; including it, we reach even 50.2 mass%. Unfortunately, H4M is\nnot stable under ambient pressure and temperature, requiring either low\ntemperature or high pressure. In this paper, we investigate the properties and\nstructure of the molecular and crystalline forms of H4M, using ab initio\nmethods based on van der Waals DFT (vdW-DF). We further investigate the\npossibility of creating the pressures required to stabilize H4M through\nexternal agents such as metal organic framework (MOF) materials and carbon\nnanotubes, with very encouraging results. In particular, we find that certain\nMOFs can create considerable pressure for H4M in their cavities, but not enough\nto stabilize it at room temperature, and moderate cooling is still necessary.\nOn the other hand, we find that all investigated carbon nanotubes can create\nthe high pressures required for H4M to be stable at room temperature, with\ndirect implications for new and exciting hydrogen-storage applications.",
        "positive": "Tailoring the ground state of the ferrimagnet La2Ni(Ni1/3Sb2/3)O6: We report on the magnetic and structural properties of La2Ni(Ni1/3Sb2/3)O6 in\npolycrystal, single crystal and thin film samples. We found that this material\nis a ferrimagnet (Tc ~ 100 K) which possesses a very distinctive and uncommon\nfeature in its virgin curve of the hysteresis loops. We observe that bellow 20\nK it lies outside the hysteresis cycle, and this feature was found to be an\nindication of a microscopically irreversible process possibly involving the\ninterplay of competing antiferromagnetic interactions that hinder the initial\nmovement of domain walls. This initial magnetic state is overcome by applying a\ntemperature dependent characteristic field. Above this field, an isothermal\nmagnetic demagnetization of the samples yield a ground state different from the\ninitial thermally demagnetized one."
    },
    {
        "anchor": "Beyond the upper limit of magnetic anisotropy in two-dimensional\n  transition metal dichalcogenides: Exploring an upper limit of magnetic anisotropy in two-dimensional materials,\nsuch as graphene and transition metal dichalcogenides, is at the heart of\nspintronics research. Herein, an atomic-scale perpendicular magnetic anisotropy\nup to an order of 100 meV per atom, which is far beyond the ordinarily obtained\nvalue in graphene and pristine transition metal dichalcogenides, is\ndemonstrated in individual ruthenium and osmium adatoms at a monosulfur vacancy\nin molybdenum disulfide. We further propose a phenomenological model where a\nspin state transition that involves hybridization between molybdenum a1 and\nadatomic e' orbitals is a possible mechanism for magnetization reorientation.",
        "positive": "Structural, Dielectric, Semiconducting and optical properties of\n  High-Energy Ball Milled YFeO3 Nano-particles: In this work, we report the effects of calcination temperature on structural,\ndielectric, semiconducting and optical properties of YFeO3 nanoparticles\nprepared by a high energy ball milling process. The structural analysis of the\nX-ray diffraction data shows that YFeO3 exists in orthorhombic as well as in\nhexagonal mixed-phase states. The Rietveld analysis confirms that orthorhombic\nYFeO3 crystallizes into Pnma space group. The optical band gap of YFeO3 reduces\nfrom 1.96 eV to 1.68 eV with increasing the calcination temperature of the\nYFeO3 sample. The bandgap reducing effect might be attributed to the increased\ncrystallite size and decreased lattice strain which is confirmed by the\nWilliamson-Hall plot method. The obtained low bandgap YFeO3 ceramic may provide\na new possibility to develop eco-friendly Ferroelectric photovoltaic devices."
    },
    {
        "anchor": "Unified modelling of the thermoelectric properties in SrTiO3: Thermoelectric materials are opening a promising pathway to address energy\nconversion issues governed by a competition between thermal and electronic\ntransport. Improving the efficiency is a difficult task, a challenge that\nrequires new strategies to unearth optimized compounds. We present a theory of\nthermoelectric transport in electron doped SrTiO3, based on a realistic tight\nbinding model that includes relevant scattering processes. We compare our\ncalculations against a wide panel of experimental data, both bulk and thin\nfilms. We find a qualitative and quantitative agreement over both a wide range\nof temperatures and carrier concentrations, from light to heavily doped.\nMoreover, the results appear insensitive to the nature of the dopant La, B, Gd\nand Nb. Thus, the quantitative success found in the case of SrTiO3, reveals an\nefficient procedure to explore new routes to improve the thermoelectric\nproperties in oxides.",
        "positive": "Plasmonic enhancement of molecular hydrogen dissociation on metallic\n  magnesium nanoclusters: Light-driven plasmonic enhancement of chemical reactions on metal catalysts\nis a promising strategy to achieve highly selective and efficient chemical\ntransformations. The study of plasmonic catalyst materials has traditionally\nfocused on late transition metals such as Au, Ag, and Cu. In recent years,\nthere has been increasing interest in the plasmonic properties of a set of\nearth-abundant elements such as Mg, which exhibit interesting hydrogenation\nchemistry with potential applications in hydrogen storage. This work explores\nthe optical, electronic, and catalytic properties of a set of metallic Mg\nnanoclusters with up to 2057 atoms using time-dependent density functional\ntight-binding and density functional theory calculations. Our results show that\nMg nanoclusters are able to produce highly energetic hot electrons with\nenergies of up to 4 eV. By electronic structure analysis, we find that these\nhot electrons energetically align with electronic states of physisorbed\nmolecular hydrogen, occupation of which by hot electrons can promote the\nhydrogen dissociation reaction. We also find that the reverse reaction,\nhydrogen evolution on metallic Mg, can potentially be promoted by hot\nelectrons, but following a different mechanism. Thus, from a theoretical\nperspective, Mg nanoclusters display very promising behaviour for their use in\nlight promoted storage and release of hydrogen."
    },
    {
        "anchor": "Stochastic theory of ferroelectric domain structure formation dominated\n  by quenched disorder: A self-consistent stochastic model of domain structure formation in a\nuniaxial ferroelectric, quenched from a high-temperature paraelectric phase to\na low-temperature ferroelectric phase, is developed with an account of the\napplied electric field and the feedback effect via local depolarization fields.\nBoth polarization and field components are considered as Gauss random\nvariables. A system of integro-differential equations for correlation functions\nof all involved variables is derived and solved analytically and numerically.\nPhase diagram in terms of the average value and dispersion of polarization\nreveals different possible equilibrium states and available final single-domain\nand multi-domain states. The time-dependent evolution of the average\npolarization and dispersion discloses a bifurcation behavior and the\ntemperature-dependent value of the electric field, deciding between the\nsingle-domain and multi-domain final states, which can be interpreted as the\ncoercive field. Analytical and numerical results for the time-dependent\ncorrelation length and correlation functions exhibit plausible agreement with\navailable experimental data.",
        "positive": "Field-effect transistors made from solution-grown two-dimensional\n  tellurene: The reliable production of two-dimensional crystals is essential for the\ndevelopment of new technologies based on 2D materials. However, current\nsynthesis methods suffer from a variety of drawbacks, including limitations in\ncrystal size and stability. Here, we report the fabrication of large-area,\nhigh-quality 2D tellurium (tellurene) using a substrate-free solution process.\nOur approach can create crystals with a process-tunable thickness, from\nmonolayer to tens of nanometres, and with lateral sizes of up to 100 um. The\nchiral-chain van der Waals structure of tellurene gives rise to strong in-plane\nanisotropic properties and large thickness dependent shifts in Raman\nvibrational modes, which is not observed in other 2D layered materials. We also\nfabricate tellurene field-effect transistors, which exhibit air-stable\nperformance at room temperature for over two months, on off ratios on the order\nof 106 and field-effect mobilities of around 700 cm2 per Vs. Furthermore, by\nscaling down the channel length and integrating with high-k dielectrics,\ntransistors with a significant on-state current density of 1 A mm-1 are\ndemonstrated."
    },
    {
        "anchor": "Current-induced fragmentation of antiferromagnetic domains: Electrical and optical pulsing allow for manipulating the order parameter and\nmagnetoresistance of antiferromagnets, opening novel prospects for digital and\nanalog data storage in spintronic devices. Recent experiments in CuMnAs have\ndemonstrated giant resistive switching signals in single-layer\nantiferromagnetic films together with analog switching and relaxation\ncharacteristics relevant for neuromorphic computing. Here we report\nsimultaneous electrical pulsing and scanning NV magnetometry of\nantiferromagnetic domains in CuMnAs performed using a pump-probe scheme. We\nobserve a nano-scale fragmentation of the antiferromagnetic domains, which is\ncontrolled by the current amplitude and independent on the current direction.\nThe fragmented antiferromagnetic state conserves a memory of the pristine\ndomain pattern, towards which it relaxes. Domain fragmentation coexists with\npermanent switching due to the reorientation of the antiferromagnetic moments.\nOur simultaneous imaging and resistance measurements show a correlation between\nthe antiferromagnetic domain fragmentation and the largest resistive switching\nsignals in CuMnAs.",
        "positive": "Recent Advances in Nanostructured Thermoelectric Half-Heusler Compounds: Half-Heusler (HH) alloys have attracted considerable interest as promising\nthermoelectric (TE) materials in the temperature range around 700 K and above,\nwhich is close to the temperature range of most industrial waste heat sources.\nThe past few years have seen nanostructuing play an important role in\nsignificantly enhancing the TE performance of several HH alloys. In this\narticle, we briefly review the recent progress and advances in these HH\nnanocomposites. We begin by presenting the structure of HH alloys and the\ndifferent strategies that have been utilized for improving the TE properties of\nHH alloys. Next, we review the details of HH nanocomposites as obtained by\ndifferent techniques. Finally, the review closes by highlighting several\npromising strategies for further research directions in these very promising TE\nmaterials."
    },
    {
        "anchor": "Ideal Strength of Doped Graphene: While the mechanical distortions change the electronic properties of graphene\nsignificantly, the effects of electronic manipulation on its mechanical\nproperties have not been known. Using first-principles calculation methods, we\nshow that, when graphene expands isotropically under equibiaxial strain, both\nthe electron and hole doping can maintain or improve its ideal strength\nslightly and enhance the critical breaking strain dramatically. Contrary to the\nisotropic expansions, the electron doping decreases the ideal strength as well\nas critical strain of uniaxially strained graphene while the hole doping\nincreases the both. Distinct failure mechanisms depending on type of strains\nare shown to be origins of the different doping induced mechanical stabilities.\nOur findings may resolve a contradiction between recent experimental and\ntheoretical results on the strength of graphene.",
        "positive": "Atomic scale lattice distortions and domain wall profiles: We present an atomic scale theory of lattice distortions using strain related\nvariables and their constraint equations. Our approach connects constrained\n{\\it atomic length} scale variations to {\\it continuum} elasticity and\ndescribes elasticity at several length scales. We apply the approach to a\ntwo-dimensional square lattice with a monatomic basis, and find the elastic\ndeformations and hierarchical atomic relaxations in the vicinity of a domain\nwall between two different homogeneous strain states. We clarify the\nmicroscopic origin of gradient terms, some of which are included\nphenomenologically in Ginzburg-Landau theory, by showing that they are\nanisotropic."
    },
    {
        "anchor": "High voltage transition metal-free cathode material LiBC3F4 for Li ion\n  batteries: The structural stability and electrochemical performance of boron substituted\nfluorinated graphite as a Li ion batteries cathode material are studied by\nfirst principles calculations. The results show that boron substituted\nfluorinated graphite BC3F4 possesses excellent structural stability, good\nelectrical and ionic conductivities. Unexpectedly, the average Li intercalation\nvoltage of LiBC3F4 is up to 4.44 V, which is much larger than that of LiBCF2.\nThe average voltage of LiBC3F4 is even larger than that of common commercial\ntransition metal oxides cathodes, indicating that LiBC3F4 is a breakthrough of\ntransition metal-free high voltage cathode materials. By comparing the Fermi\nlevel, we found the Fermi level of LiBC3F4 is 1.38 eV lower than that of\nLiBCF2, leading to the decrease of the electron filling energy for the Li\nintercalation and forming much higher voltage. Moreover, LiBC3F4 shows small\nvolume expansion and high energy density. LiBC3F4 is a promising high voltage\ncathode material for Li ion batteries. Finally, by calculating the evolution of\nLi intercalation voltage and Fermi level during the discharging process, a\nlinear correlation between the Fermi level and Li intercalation voltage has\nbeen found.",
        "positive": "Auxetic properties of a newly proposed $\u03b3$-graphyne-like material: In this work, we propose a new auxetic (negative Poisson's ratio values)\nstructure, based on a $\\gamma$-graphyne structure, here named $A\\gamma G$\n$structure$. Graphynes are 2D carbon allotropes with phenylic rings connected\nby acetylenic groups. The A$\\gamma$G structural/mechanical and electronic\nproperties, as well as its thermal stability, were investigated using classical\nreactive and quantum molecular dynamics simulations. We found that A$\\gamma$G\nhas a large bandgap of 2.48 eV and is thermally stable at a large range of\ntemperatures. It presents a Young's modulus that is an order of magnitude\nsmaller than that of graphene or $\\gamma$-graphyne. The classical and quantum\nresults are consistent and validate that the A$\\gamma$G is auxetic, both when\nisolated (vacuum) and when deposited on a copper substrate. We believe that\nthis is the densest auxetic structure belonging to the graphyne-like families."
    },
    {
        "anchor": "Electric-Field Control of Magnetic Order: From FeRh to Topological\n  Antiferromagnetic Spintronics: Using an electric field instead of an electric current (or a magnetic field)\nto tailor the electronic properties of magnetic materials is promising for\nrealizing ultralow energy-consuming memory devices because of the suppression\nof Joule heating, especially when the devices are scaled to the nanoscale. In\nthe review, we summarize recent results on the giant magnetization and\nresistivity modulation in a metamagnetic intermetallic alloy - FeRh, which is\nachieved by electric-field-controlled magnetic phase transitions in\nmultiferroic heterostructures. Furthermore, the approach is extended to\ntopological antiferromagnetic spintronics, which is currently receiving\nattention in the magnetic society, and the antiferromagnetic order parameter\nhas been able to switch back and forth by a small electric field. In the end,\nwe envision the possibility of manipulating exotic physical phenomena in the\nemerging topological antiferromagnetic spintronics field via the electric-field\napproach.",
        "positive": "Neutral-cluster implantation in polymers by computer experiments: In this work we perform atomistic model potential molecular dynamics\nsimulations by means of state-of-the art force-fields to study the implantation\nof a single Au nanocluster on a Polydimethylsiloxane substrate. All the\nsimulations have ben performed on realistic substrate models containing up to\n4.6 millions of atoms having depths up to 90 nm and lateral dimensions up to 25\nnm. We consider both entangled-melt and cross-linked Polydimethylsiloxane\namorphous structures. We show that even a single cluster impact on the\nPolydimethylsiloxane substrate remarkably changes the polymer local temperature\nand pressure. Moreover we observe the presence of craters created on the\npolymer surface having lateral dimensions comparable to the cluster radius and\ndepths strongly dependent on the implantation energy. Present simulations\nsuggest that the substrate morphology is largely affected by the cluster impact\nand that most-likely such modifications favor the the penetration of the next\nimpinging clusters."
    },
    {
        "anchor": "Thermal conductivity of iron and nickel during melting: Implication to\n  Planetary liquid outer core: We report the measurements of the thermal conductivity ($\\kappa$) of iron\n(Fe) and nickel (Ni) at high pressures and high temperatures. $\\kappa$ values\nare estimated from the temperature measurements across the sample surface in a\nlaser heated diamond anvil cell (LHDAC) and using the COMSOL software.\nNear-isothermal $\\kappa$'s are observed to increase with pressure in both the\nmetals due to the increase of density of the pressed metals. In both metals\n$\\kappa$'s are observed to follow a sharp fall during melting at different\npressure points and are consistence with the other multi-anvil measurements.\nConstant values of $\\kappa$ in these metals during melting at different\npressures reveal the loss of long range order, which creates independent\nmovement of atomic metals. The melting temperature measured in these metals\nfrom the sudden drop of $\\kappa$-values are in a good agreement with the other\nmelting measurements in LHDAC. The results obtained in this study is expected\nto provide an insight to the studies on the planets Mercury and Mars and their\ninterior.",
        "positive": "Geometrical meaning of the Drude weight and its relationship to orbital\n  magnetization: At the mean-field level the Drude weight is the Fermi-volume integral of the\neffective inverse mass tensor. I show here that the deviation of the inverse\nmass from its free-electron value is the real symmetric part of a geometrical\ntensor, which is naturally endowed with an imaginary antisymmetric part. The\nFermi-volume integral of the latter yields the orbital magnetization. The novel\ngeometrical tensor has a very compact form, and looks like a close relative of\nthe familiar metric-curvature tensor. The Fermi-volume integral of each of the\ntwo tensors provides (via real and imaginary parts) a couple of macroscopic\nobservables of the electronic ground-state. I discuss the whole quartet, for\nboth insulating and metallic crystals."
    },
    {
        "anchor": "TBPLaS: a Tight-Binding Package for Large-scale Simulation: TBPLaS is an open-source software package for the accurate simulation of\nphysical systems with arbitrary geometry and dimensionality utilizing the\ntight-binding (TB) theory. It has an intuitive object-oriented Python\napplication interface (API) and Cython/Fortran extensions for the performance\ncritical parts, ensuring both flexibility and efficiency. Under the hood,\nnumerical calculations are mainly performed by both exact diagonalizatin and\nthe tight-binding propagation method (TBPM) without diagonalization.\nEspecially, the TBPM is based on the numerical solution of time-dependent\nSchr\\\"odinger equation, achieving linear scaling with system size in both\nmemory and CPU costs. Consequently, TBPLaS provides a numerically cheap\napproach to calculate the electronic, transport and optical properties of large\ntight-binding models with billions of atomic orbitals. Current capabilities of\nTBPLaS include the calculation of band structure, density of states, local\ndensity of states, quasi-eigenstates, optical conductivity, electrical\nconductivity, Hall conductivity, polarization function, dielectric function,\nplasmon dispersion, carrier mobility and velocity, localization length and free\npath, Z2 topological invariant, wave-packet propagation, etc. All the\nproperties can be obtained with only a few lines of code. Other algorithms\ninvolving tight-binding Hamiltonians can be implemented easily thanks to its\nextensible and modular nature. In this paper, we discuss the theoretical\nframework, implementation details and common workflow of TBPLaS, and give a few\ndemonstrations of its applications.",
        "positive": "Manipulation of magnetic topological textures via perpendicular strain\n  and polarization in van der Waals magnetoelectric heterostructure: Multi-functional manipulation of magnetic topological textures such as\nskyrmions and bimerons in energy-efficient ways is of great importance for\nspintronic applications, but still being a big challenge. Here, by\nfirst-principles calculations and atomistic simulations, the creation and\nannihilation of skyrmions/bimerons, as key operations for the reading and\nwriting of information in spintronic devices, are achieved in van der Waals\nmagnetoelectric CrISe/In2Se3 heterostructure via perpendicular strain or\nelectric field without external magnetic field. Besides, the bimeron-skyrmion\nconversion, size modulation and the reversible magnetization switching from\nin-plane to out-of-plane could also be realized in magnetic-field-free ways.\nMoreover, the topological charge and morphology can be precisely controlled by\na small magnetic field. The strong Dzyaloshinskii-Moriya interaction and\ntunable magnetic anisotropy energy in a wide window are found to play vital\nroles in such energy efficient multi-functional manipulation, and the\nunderlying physical mechanisms are elucidated. Our work predicts the\nCrISe/In2Se3 heterostructure being an ideal platform to address this challenge\nin spintronic applications, and theoretically guides the low-dissipation\nmulti-functional manipulation of magnetic topological textures."
    },
    {
        "anchor": "Magnetic resonance spectroscopy of perpendicularly magnetized permalloy\n  multilayer disks: Using a Magnetic Resonance Force Microscope, we compare the ferromagnetic\nresonance spectra of individual micron-size disks with identical diameter, 1\n$m$m, but different layer structures. For a disk composed of a single 43.3 nm\nthick permalloy (Py) layer, the lowest energy mode in the perpendicular\nconfiguration is the uniform precession. The higher energy modes are standing\nspin-waves confined along the diameter of the disk. For a Cu(30)/Py(100)/Cu(30)\nnm multilayer structure, it has been interpreted that the lowest energy mode\nbecomes a precession localized at the Cu/Py interfaces. When the multilayer is\nchanged to Py(100)/Cu(10)/Py(10) nm, this localized mode of the thick layer is\ncoupled to the precession of the thin layer.",
        "positive": "Electronic correlation determining correlated plasmons in Sb-doped\n  Bi$_2$Se$_3$: Electronic correlation is believed to play an important role in exotic\nphenomena such as insulator-metal transition, colossal magneto resistance and\nhigh temperature superconductivity in correlated electron systems. Recently, it\nhas been shown that electronic correlation may also be responsible for the\nformation of unconventional plasmons. Herewith, using a combination of\nangle-dependent spectroscopic ellipsometry, angle resolved photoemission\nspectroscopy and Hall measurements all as a function of temperature supported\nby first-principles calculations, the existence of low-loss high-energy\ncorrelated plasmons accompanied by spectral weight transfer, a fingerprint of\nelectronic correlation, in topological insulator\n(Bi$_{0.8}$Sb$_{0.2}$)$_2$Se$_3$ is revealed. Upon cooling, the density of free\ncharge carriers in the surface states decreases whereas those in the bulk\nstates increase, and that the newly-discovered correlated plasmons are key to\nexplaining this phenomenon. Our result shows the importance of electronic\ncorrelation in determining new correlated plasmons and opens a new path in\nengineering plasmonic-based topologically-insulating devices."
    },
    {
        "anchor": "Exciton self-trapping causes picoseconds recombination in metal-organic\n  chalcogenides hybrid quantum wells: Metal-organic species can be designed to self-assemble in large-scale,\natomically defined, supramolecular architectures. Hybrid quantum wells, where\ninorganic two-dimensional (2D) planes are separated by organic ligands, are a\nparticular example. The ligands effectively provide an intralayer confinement\nfor charge carriers resulting in a 2D electronic structure, even in\nmultilayered assemblies. Air-stable metal organic chalcogenides hybrid quantum\nwells have recently been found to host tightly bound 2D excitons with strong\noptical anisotropy in a bulk matrix. Here, we investigate the excited carrier\ndynamics in the prototypical metal organic chalcogenide [AgSePh], disentangling\nthree excitonic resonances by low temperature transient absorption\nspectroscopy. Our analysis suggests a complex relaxation cascade comprising\nultrafast screening and renormalization, inter-exciton relaxation, and\nself-trapping of excitons within few picoseconds. The ps-decay provided by the\nself-trapping mechanism may be leveraged to unlock the material's potential for\nultrafast optoelectronic applications.",
        "positive": "Phonon coupling to dynamic short-range polar order in a relaxor\n  ferroelectric near the morphotropic phase boundary: We report neutron inelastic scattering experiments on single crystal\nPbMg$_{1/3}$Nb$_{2/3}$O$_{3}$ doped with 32\\% PbTiO$_{3}$, a relaxor\nferroelectric that lies close to the morphotropic phase boundary. When cooled\nunder an electric field $\\mathbf{E} \\parallel$ [001] into tetragonal and\nmonoclinic phases, the scattering cross section from transverse acoustic (TA)\nphonons polarized parallel to $\\mathbf{E}$ weakens and shifts to higher energy\nrelative to that under zero-field-cooled conditions. Likewise, the scattering\ncross section from transverse optic (TO) phonons polarized parallel to\n$\\mathbf{E}$ weakens for energy transfers $4 \\leq \\hbar \\omega \\leq 9$ meV.\nHowever, TA and TO phonons polarized perpendicular to $\\mathbf{E}$ show no\nchange. This anisotropic field response is similar to that of the diffuse\nscattering cross section, which, as previously reported, is suppressed when\npolarized parallel to $\\mathbf{E}$, but not when polarized perpendicular to\n$\\mathbf{E}$. Our findings suggest that the lattice dynamics and dynamic\nshort-range polar correlations that give rise to the diffuse scattering are\ncoupled."
    },
    {
        "anchor": "Flux growth of Sr(n+1)Ir(n)O(3n+1) [n=1, 2, infinity] crystals: Single crystals of iridates are usually grown by a flux method well above the\nboiling point of the SrCl2 solvent. This leads to non-equilibrium growth\nconditions and dramatically shortens the lifetime of expensive Pt crucibles.\nHere, we report the growth of Sr2IrO4, Sr3Ir2O7 and SrIrO3 single crystals in a\nreproducible way by using anhydrous SrCl2 flux well below its boiling point. We\nshow that the yield of the different phases strongly depends on the\nnutrient/solvent ratio for fixed soak temperature and cooling rate. Using this\nlow-temperature growth approach generally leads to a lower\ntemperature-independent contribution to the magnetic susceptibility than\npreviously reported. Crystals of SrIrO3 exhibit a paramagnetic behavior that\ncan be remarkably well fitted with a Curie-Weiss law yielding physically\nreasonable parameters, in contrast to previous reports. Hence, reducing the\nsoak temperature below the solvent boiling point not only provides more stable\nand controllable growth conditions in contrast to previously reported growth\nprotocols, but also extends considerably the lifetime of expensive platinum\ncrucibles and reduces the corrosion of heating and thermoelements of standard\nfurnaces, thereby reducing growth costs.",
        "positive": "Disorder induced phase segregation in La2/3Ca1/3MnO3 manganites: Neutron powder diffraction experiments on La2/3Ca1/3MnO3 over a broad\ntemperature range above and below the metal-insulator transition have been\nanalyzed beyond the Rietveld average approach by use of Reverse Monte Carlo\nmodelling. This approach allows the calculation of atomic pair distribution\nfunctions and spin correlation functions constrained to describe the observed\nBragg and diffuse nuclear and magnetic scattering. The results evidence phase\nseparation within a paramagnetic matrix into ferro and antiferromagnetic\ndomains correlated to anistropic lattice distortions in the vicinity of the\nmetal-insulator transition."
    },
    {
        "anchor": "A Redox-based Ion-Gating Reservoir, Utilizing Double Reservoir States in\n  Drain and Gate Nonlinear Responses: We have demonstrated physical reservoir computing with a redox-based\nion-gating reservoir (redox-IGR) comprising LixWO3 thin film and lithium ion\nconducting glass ceramic (LICGC). The subject redox-IGR successfully solved a\nsecond-order nonlinear dynamic equation by utilizing voltage pulse driven\nion-gating in a LixWO3 channel to enable reservoir computing. Under the normal\nconditions, in which only the drain current (ID) is used for the reservoir\nstates, the lowest prediction error is 7.39x10-4. Performance was enhanced by\nthe addition of IG to the reservoir states, resulting in a significant lowering\nof the prediction error to 5.06x10-4, which is noticeably lower than other\ntypes of physical reservoirs reported to date. A second-order nonlinear\nautoregressive moving average (NARMA2) task, a typical benchmark of reservoir\ncomputing, was also performed with the IGR and good performance was achieved,\nwith an NMSE of 0.163. A short-term memory task was performed to investigate an\nenhancement mechanism resulting from the IG addition. An increase in memory\ncapacity, from 1.87 without IG to 2.73 with IG, was observed in the forgetting\ncurves, indicating that enhancement of both high dimensionality and memory\ncapacity are attributed to the origin of the performance improvement.",
        "positive": "On the Corrosion Resistance of Porous Electroplated Zinc Coatings in\n  Different Corrosive Media: The corrosion resistance of an electroplated (EP) Zn coating whose surface\nwas chemically etched to produce surface defects (pores) is investigated in\nthis work. Impedance and DC polarisation measururements were employed to study\nthe behaviour of such coating in various corrosive media (NaCl, NaOH and rain\nwater). Four different faradaic relaxation processes were clearly revealed in\ndifferent NaCl concentrations (from 0.1M to 1M). In the most concentrated\nsolutions at least three relaxation processes at low frequencies (LF) appeared\nand were related to zinc deposition and dissolution. At lower concentrations\nand depending on the pH, only one process was observed. The charge transfer\nresistance (Rct) and the corrosion current (Icorr) were practically stable in\nthe pH range 5 to 10. In deaerated NaCl 0.1M, the EIS diagrams showed two\ntime-constants at very close frequencies. From the EIS diagrams the porous\nnature of the coating was highlighted and showed that the dissolution\nmechanisms occurred at the base of the pores."
    },
    {
        "anchor": "Control of Dzyaloshinskii-Moriya interaction in Mn$_{1-x}$Fe$_x$Ge: a\n  first-principles study: Motivated by the recent experiment on the size and helicity control of\nskyrmions in Mn$_{1-x}$Fe$_x$Ge [K. Shibata et al., Nature Nanotechnology 8,\n732 (2013)], we study how the Dzyaloshinskii-Moriya (DM) interaction changes\nits size and sign in metallic helimagnets. By means of first-principles\ncalculations, we successfully reproduce the non-trivial sign change of the DM\ninteraction observed in the experiment. While the DM interaction sensitively\ndepends on the carrier density or the detail of the electronic structure such\nas the size of the exchange splitting, its behavior can be systematically\nunderstood in terms of the distribution of anticrossing points in the band\nstructure. By following this guiding principle, we can even induce gigantic\nanisotropy in the DM interaction by applying a strain to the system. These\nresults pave the new way for skyrmion crystal engineering in metallic\nhelimagnets.",
        "positive": "Anomalous behavior in the phonon dispersion of the (001) surface of\n  Bi$_2$Te$_3$ determined from helium atom-surface scattering measurements: We employ inelastic helium atom-surface scattering to measure the low energy\nphonon dispersion along high-symmetry directions on the surface of the\ntopological insulator Bi$_2$Te$_3$. Results indicate that one particular\nlow-frequency branch experiences noticeable mode softening attributable to the\ninteraction between Dirac fermion quasiparticles and phonons on the surface.\nThis mode softening constitutes a renormalization of the real part of the\nphonon self-energy. We obtain the imaginary part, and hence lifetime\ninformation, via a Hilbert transform. In doing so we are able to calculate an\naverage branch specific electron-phonon coupling constant $<\\lambda_\\nu> =\n1.44$."
    },
    {
        "anchor": "From Anomalous Hall Effect to the Quantum Anomalous Hall Effect: A short review paper for the quantum anomalous Hall effect. A substantially\nextended one is published as Adv. Phys. 64, 227 (2015).",
        "positive": "Topological Hall Effect in a Topological Insulator Interfaced with a\n  Magnetic Insulator: A topological insulator (TI) interfaced with a magnetic insulator (MI) may\nhost an anomalous Hall effect (AHE), a quantum AHE, and a topological Hall\neffect (THE). Recent studies, however, suggest that coexisting magnetic phases\nin TI/MI heterostructures may result in an AHE-associated response that\nresembles a THE but in fact is not. This article reports a genuine THE in a\nTI/MI structure that has only one magnetic phase. The structure shows a THE in\nthe temperature range of T=2-3 K and an AHE at T=80-300 K. Over T=3-80 K, the\ntwo effects coexist but show opposite temperature dependencies. Control\nmeasurements, calculations, and simulations together suggest that the observed\nTHE originates from skyrmions, rather than the coexistence of two AHE\nresponses. The skyrmions are formed due to an interfacial DMI interaction. The\nDMI strength estimated is substantially higher than that in heavy metal-based\nsystems."
    },
    {
        "anchor": "A multimodal operando neutron study of the phase evolution in a graphite\n  electrode: Obtaining a complete picture of local processes still poses a significant\nchallenge in battery research. Here we demonstrate an in-situ combination of\nmultimodal neutron imaging with neutron diffraction for spatially resolved\noperando observations of the lithiation-delithiation of a graphite electrode in\na Li-ion battery cell. Throughout the lithiation-delithiation process we image\nthe Li distribution based on the local beam attenuation. Simultaneously, we\nobserve the development of the lithiated graphite phases as a function of\ncycling time and electrode thickness and integral throughout its volume by\ndiffraction contrast imaging and diffraction, respectively. While the\nconventional imaging data allows to observe the Li uptake in graphite already\nduring the formation of the solid electrolyte interphase, diffraction indicates\nthe onset and development of the Li insertion/extraction globally, which\nsupports the local structural transformation observations by diffraction\ncontrast imaging.",
        "positive": "Localized Electron States Near a Metal-Semiconductor Nanocontact: The electronic structure of nanowires in contact with metallic electrodes of\nexperimentally relevant sizes is calculated by incorporating the electrostatic\npolarization potential into the atomistic single particle Schr\\\"odinger\nequation. We show that the presence of an electrode produces localized\nelectron/hole states near the electrode, a phenomenon only exhibited in\nnanostructures and overlooked in the past. This phenomenon will have profound\nimplications on electron transport in such nanosystems. We calculate several\nelectrode/nanowire geometries, with varying contact depths and nanowire radii.\nWe demonstrate the change in the band gap of up to 0.5 eV in 3 nm diameter CdSe\nnanowires and calculate the magnitude of the applied electric field necessary\nto overcome the localization."
    },
    {
        "anchor": "Thermodynamic theory of dislocation-enabled plasticity: The thermodynamic theory of dislocation-enabled plasticity is based on two\nunconventional hypotheses. The first of these is that a system of dislocations,\ndriven by external forces and irreversibly exchanging heat with its\nenvironment, must be characterized by a thermodynamically defined effective\ntemperature that is not the same as the ordinary temperature. The second\nhypothesis is that the overwhelmingly dominant mechanism controlling plastic\ndeformation is thermally activated depinning of entangled pairs of\ndislocations. This paper consists of a systematic reformulation of this theory\nfollowed by examples of its use in analyses of experimentally observed\nphenomena including strain hardening, grain-size (Hall-Petch) effects, yielding\ntransitions, and adiabatic shear banding.",
        "positive": "A Hybrid-DFT Study of Intrinsic Point Defects in $MX_2$ ($M$=Mo, W;\n  $X$=S, Se) Monolayers: Defects can strongly influence the electronic, optical and mechanical\nproperties of 2D materials, making defect stability under different\nthermodynamic conditions crucial for material-property engineering. In this\npaper, we present an account of the structural and electronic characteristics\nof point defects in monolayer transition metal dichalcogenides $MX_2$ with\n$M$=Mo/W and $X$= S/Se, calculated with density-functional theory using the\nhybrid HSE06 exchange correlation functional including many-body dispersion\ncorrections. For the simulation of charged defects, we employ a charge\ncompensation scheme based on the virtual crystal approximation (VCA). We relate\nthe stability and the electronic structure of charged vacancy defects in\nmonolayer MoS$_2$ to an explicit calculation of the S monovacancy in MoS$_2$\nsupported on Au(111), and find convincing indication that the defect is\nnegatively charged. Moreover, we show that the finite-temperature vibrational\ncontributions to the free energy of defect formation can change the stability\ntransition between adatoms and monovacancies by 300--400 K. Finally, we probe\ndefect vibrational properties by calculating a tip-enhanced Raman scattering\nimage of a vibrational mode of a MoS$_2$ cluster with and without an S\nmonovacancy."
    },
    {
        "anchor": "Observation of the anomalous Nernst effect in altermagnetic candidate\n  Mn5Si3: The anomalous Nernst effect generates transverse voltage to the applied\nthermal gradient in magnetically ordered systems. The effect was previously\nconsidered excluded in compensated magnetic materials with collinear ordering.\nHowever, in the recently identified class of compensated magnetic materials,\ndubbed altermagnets, time-reversal symmetry breaking in the electronic band\nstructure makes the presence of the anomalous Nernst effect possible despite\nthe collinear spin arrangement. In this work, we investigate epitaxial Mn5Si3\nthin films known to be an altermagnetic candidate. We show that the material\nmanifests a sizable anomalous Nernst coefficient despite the small net\nmagnetization of the films. The measured magnitudes of the anomalous Nernst\ncoefficient reach a scale of microVolts per Kelvin. We support our\nmagneto-thermoelectric measurements by density-functional theory calculations\nof the material's spin-split electronic structure, which allows for the finite\nBerry curvature in the reciprocal space. Furthermore, we present our\ncalculations of the intrinsic Berry-curvature Nernst conductivity, which agree\nwith our experimental observations.",
        "positive": "Nucleation of Dislocations in 3.9 nm Nanocrystals at High Pressure: As circuitry approaches single nanometer length scales, it is important to\npredict the stability of metals at these scales. The behavior of metals at\nlarger scales can be predicted based on the behavior of dislocations, but it is\nunclear if dislocations can form and be sustained at single nanometer\ndimensions. Here, we report the formation of dislocations within individual 3.9\nnm Au nanocrystals under nonhydrostatic pressure in a diamond anvil cell. We\nused a combination of x-ray diffraction, optical absorbance spectroscopy, and\nmolecular dynamics simulation to characterize the defects that are formed,\nwhich were found to be surface-nucleated partial dislocations. These results\nindicate that dislocations are still active at single nanometer length scales\nand can lead to permanent plasticity."
    },
    {
        "anchor": "Stability of magnetic configurations in nanorings: The relative stability of the vortex, onion and ferromagnetic phases in\nnanorings is examined as a function of the ring geometry. Total energy\ncalculations are carried out analytically, based on simple models for each\nconfiguration. Results are summarized by phase diagrams, which might be used as\na guide to the production of rings with specific magnetic properties.",
        "positive": "Dual Behavior of Antiferromagnetic Uncompensated Spins in NiFe/IrMn\n  Exchange Biased Bilayers: We present a comprehensive study of the exchange bias effect in a model\nsystem. Through numerical analysis of the exchange bias and coercive fields as\na function of the antiferromagnetic layer thickness we deduce the absolute\nvalue of the averaged anisotropy constant of the antiferromagnet. We show that\nthe anisotropy of IrMn exhibits a finite size effect as a function of\nthickness. The interfacial spin disorder involved in the data analysis is\nfurther supported by the observation of the dual behavior of the interfacial\nuncompensated spins. Utilizing soft x-ray resonant magnetic reflectometry we\nhave observed that the antiferromagnetic uncompensated spins are dominantly\nfrozen with nearly no rotating spins due to the chemical intermixing, which\ncorrelates to the inferred mechanism for the exchange bias."
    },
    {
        "anchor": "On The Role Of The Interface Charge In Non-Ideal Metal-Semiconductor\n  Contacts: The bias dependent interface charge is considered as the origin of the\nobserved non-ideality in current-voltage and capacitance-voltage\ncharacteristics. Using the simplified model for the interface electronic\nstructure based on defects interacting with the continuum of interface states,\nthe microscopic origin of empirical parameters describing the bias dependent\ninterface charge function is investigated. The results show that in non-ideal\nmetal-semiconductor contacts the interface charge function depends on the\ninterface disorder parameter, density of defects, barrier pinning parameter and\nthe effective gap center. The theoretical predictions are tested against\nseveral sets of published experimental data on bias dependent ideality factor\nand excess capacitance in various metal-semicoductor systems.",
        "positive": "Nodal line semimetal states in positive electrode material of lead-acid\n  battery: Lead dioxide family and its derivatives: Based on first-principles calculations and symmetry analysis, we report that\nthe three-dimensional (3D) nodal line (NL) semimetal phases can be realized in\nthe lead dioxide family (\\emph{$\\alpha$}-PbO$_2$ and \\emph{$\\beta$}-PbO$_2$)\nand its derivatives. The \\emph{$\\beta$}-PbO$_2$ features two orthogonal nodal\nrings around the Fermi level, protected by the mirror reflection symmetry. The\neffective model is developed and the related parameters are given by fitting\nwith the HSE06 band structures. The NLs mainly come from the $p$ orbitals of\nthe light element O and are rather robust against such tiny spin-orbit\ncoupling. The NL phase of the \\emph{$\\alpha$}-PbO$_2$ can be effectively\ntailored by strain, making a topological phase transition between a\nsemiconductor phase and a NL phase. In addition, the exploration of\n\\emph{$\\beta$}-PbO$_2$ derivatives (i.e. \\emph{$\\beta$}-PbS$_2$ and\n\\emph{$\\beta$}-PbSe$_2$) and confirmation of their topological semimetallicity\ngreatly enrich the NL semimetal family. These findings pave a route for\ndesigning topological NL semimetals and spintronic devices based on realistic\nPbO$_2$ family."
    },
    {
        "anchor": "Predicted phase diagram of B-C-N: Noting the structural relationships between phases of carbon and boron\ncarbide with phases of boron nitride and boron subnitride, we investigate their\nmutual solubilities using a combination of first principles total energies\nsupplemented with statistical mechanics to address finite temperatures. Owing\nto large energy costs of substitution, we find the mutual solubilities of the\nultra hard materials diamond and cubic boron nitride are negligible, and the\nsame for the quasi-two dimensional materials graphite and hexagonal boron\nnitride. In contrast, we find a continuous range of solubility connecting boron\ncarbide to boron subnitride at elevated temperatures. The electron precise\ncompound B$_{13}$CN consisting of B$_{12}$ icosahedra with NBC chains is found\nto be stable at all temperatures up to melting. It exhibits an order-disorder\ntransition in the orientation of NBC chains at approximately T=500K.",
        "positive": "Improving reconstructions in nanotomography for homogeneous materials\n  via mathematical optimization: Compressed sensing is an image reconstruction technique to achieve\nhigh-quality results from limited amount of data. In order to achieve this, it\nutilizes prior knowledge about the samples that shall be reconstructed.\nFocusing on image reconstruction in nanotomography, this work proposes\nenhancements by including additional problem-specific knowledge. In more\ndetail, we propose further classes of algebraic inequalities that are added to\nthe compressed sensing model. The first consists in a valid upper bound on the\npixel brightness. It only exploits general information about the projections\nand is thus applicable to a broad range of reconstruction problems. The second\nclass is applicable whenever the sample material is of roughly homogeneous\ncomposition. The model favors a constant density and penalizes deviations from\nit. The resulting mathematical optimization models are algorithmically\ntractable and can be solved to global optimality by state-of-the-art available\nimplementations of interior point methods. In order to evaluate the novel\nmodels, obtained results are compared to existing image reconstruction methods,\ntested on simulated and experimental data sets. The experimental data comprise\none 360{\\deg} electron tomography tilt series of a macroporous zeolite particle\nand one absorption contrast nano X-ray computed tomography (nano-CT) data set\nof a copper microlattice structure. The enriched models are optimized quickly\nand show improved reconstruction quality, outperforming the existing models.\nPromisingly, our approach yields superior reconstruction results, particularly\nwhen information about the samples is available for a small number of tilt\nangles only"
    },
    {
        "anchor": "Quasiparticle Band Gaps, Excitonic Effects, and Anisotropic Optical\n  Properties of Monolayer Distorted 1-T Diamond-chain Structures: We report many-body perturbation theory calculations of excited-state\nproperties of distorted 1-T diamond-chain monolayer rhenium disulfide (ReS2)\nand diselenide (ReSe2). Electronic self-energy substantially enhances their\nquasiparticle band gaps and, surprisingly, converts monolayer ReSe2 to a\ndirect-gap semiconductor, which was, however, regarded to be an indirect one by\ndensity-functional-theory calculations. Their optical absorption spectra are\ndictated by strongly bound excitons. Unlike hexagonal structures, the\nlowest-energy bright exciton of distorted 1-T ReS2 exhibits a perfect figure-8\nshape polarization dependence but those of ReSe2 only exhibit a partial\npolarization dependence, which results from two nearly-degenerated bright\nexcitons whose polarization preferences are not aligned. Our first-principles\ncalculations are in agreement with experiments and pave the way for\noptoelectronic applications.",
        "positive": "Electronic and magnetic properties of $\u03b1$-FeGe$_2$ films embedded\n  in vertical spin valve devices: We studied metastable $\\alpha$-FeGe$_2$, a novel layered tetragonal material,\nembedded as a spacer layer in spin valve structures with ferromagnetic Fe$_3$Si\nand Co$_2$FeSi electrodes. For both types of electrodes, spin valve operation\nis demonstrated with a metallic transport behavior of the $\\alpha$-FeGe$_2$\nspacer layer. The spin valve signals are found to increase both with\ntemperature and spacer thickness, which is discussed in terms of a decreasing\nmagnetic coupling strength between the ferromagnetic bottom and top electrodes.\nThe temperature-dependent resistances of the spin valve structures exhibit\ncharacteristic features, which are explained by ferromagnetic phase transitions\nbetween 55 and 110~K. The metallic transport characteristics as well as the\nlow-temperature ferromagnetism are found to be consistent with the results of\nfirst-principles calculations."
    },
    {
        "anchor": "Helium Behavior in Oxide Nuclear Fuels: First Principles Modeling: UO2 and (U,Pu)O2 solid solutions (the so-called MOX) nowadays are used as\ncommercial nuclear fuels in many countries. One of the safety issues during the\nstorage of these fuels is related to their self-irradiation that produces and\naccumulates point defects and helium therein. We present density functional\ntheory (DFT) calculations for UO2, PuO2 and MOX containing He atoms in\noctahedral interstitial positions. In particular, we calculated basic MOX\nproperties and He incorporation energies as functions of Pu concentration\nwithin the spin-polarized, generalized gradient approximation (GGA) DFT\ncalculations. We also included the on-site electron correlation corrections\nusing the Hubbard model (in the framework of the so-called DFT+U approach). We\nfound that PuO2 remains semiconducting with He in the octahedral position while\nUO2 requires a specific lattice distortion. Both materials reveal a positive\nenergy for He incorporation, which, therefore, is an exothermic process. The He\nincorporation energy increases with the Pu concentration in the MOX fuel.",
        "positive": "Suppression of atomic displacive excitation in photo-induced\n  A$_{\\mathrm{1g}}$ phonon mode of bismuth unveiled by low-temperature\n  time-resolved x-ray diffraction: An ultrafast atomic motion of a photo-induced coherent phonon of bismuth at\nlow temperatures was directly observed with time-resolved x-ray diffraction. A\ncryostat with a window that is transparent to both optical lasers and x-rays\nenabled versatile diffraction measurements in a wide temperature range\nincluding below 10 K. It is found that an atomic displacement in a fully\nsymmetric A$_{\\mathrm{1g}}$ phonon mode is suppressed at low temperatures. This\nresult indicates the displacive excitation process is suppressed in the phonon\ngeneration with decreasing temperature."
    },
    {
        "anchor": "Monolithically integrated 940 nm half VCSELs on bulk Ge substrates: High quality n-type AlGaAs distributed Bragg reflectors (DBRs) and lnGaAs\nmultiple quantum wells were successfully monolithically grown on 4-inch off-cut\nGe (100) wafers. The grown structures have photoluminescence spectra and\nreflectance spectra comparable to those grown on conventional bulk GaAs wafers\nand have smooth morphology and reasonable uniformity. These results strongly\nsupport full VCSEL growth and fabrication on larger-area bulk Ge substrates for\nthe mass production of AlGaAs-based VCSELs.",
        "positive": "Thickness dependence of the stability of the charge-ordered state in\n  Pr$_{0.5}$Ca$_{0.5}$MnO$_{3}$ thin films: Thin films of the charge-ordered (CO) compound Pr$_{0.5}$Ca$_{0.5}$MnO$_{3}$\nhave been deposited onto (100)-oriented SrTiO$_{3}$ substrates using the Pulsed\nLaser Deposition technique. Magnetization and transport properties are measured\nwhen the thickness of the film is varied. While the thinner films do not\nexhibit any temperature induced insulator-metal transition under an applied\nmagnetic field up to 9T, for thickness larger than 1100\\UNICODE{0xc5} a 5T\nmagnetic field is sufficient to melt the CO state. For this latest film, we\nhave measured the temperature-field phase diagram. Compared to the bulk\nmaterial, it indicates that the robustness of the CO state in thin films is\nstrongly depending on the strains and the thickness. We proposed an explanation\nbased on the distortion of the cell of the film."
    },
    {
        "anchor": "Hardness and fracture toughness models by symbolic regression: Superhard materials with good fracture toughness have found wide industrial\napplications, which necessitates the development of accurate hardness and\nfracture toughness models for efficient materials design. Although several\nmacroscopic models have been proposed, they are mostly semiempirical based on\nprior knowledge or assumptions, and obtained by fitting limited experimental\ndata. Here, through an unbiased and explanatory symbolic regression technique,\nwe built a macroscopic hardness model and fracture toughness model, which only\nrequire shear and bulk moduli as inputs. The developed hardness model was\ntrained on an extended dataset, which not only includes cubic systems, but also\ncontains non-cubic systems with anisotropic elastic properties. The obtained\nmodels turned out to be simple, accurate, and transferable. Moreover, we\nassessed the performance of three popular deep learning models for predicting\nbulk and shear moduli, and found that the crystal graph convolutional neural\nnetwork and crystal explainable property predictor perform almost equally well,\nboth better than the atomistic line graph neural network. By combining the\nmachine-learned bulk and shear moduli with the hardness and fracture toughness\nprediction models, potential superhard materials with good fracture toughness\ncan be efficiently screened out through high-throughput calculations.",
        "positive": "Switching of the Chiral Magnetic Domains in the Hybrid Multiferroic\n  (ND4)2[FeCl5(D2O)]: Neutron spherical polarimetry, which is directly sensitive to the absolute\nmagnetic configuration and domain population, has been used in this work to\nunambiguously prove the multiferroicity of (ND4)2[FeCl5(D2O)]. We demonstrate\nthat the application of an electric field upon cooling results in the\nstabilization of a single-cycloidal magnetic domain below 6.9 K, while poling\nin the opposite electric field direction produces the full population of the\ndomain with opposite magnetic chirality. We prove the complete switchability of\nthe magnetic domains at low temperature by the applied electric field, which\nconstitutes a direct proof of the strong magnetoelectric coupling.\nAdditionally, we refine the magnetic structure of the ordered ground state,\ndetermining the underlying magnetic space group consistent with the direction\nof the ferroelectric polarization, and we provide evidence of a collinear\namplitude-modulated state with magnetic moments along the a-axis in the\ntemperature region between 6.9 and 7.2 K."
    },
    {
        "anchor": "A phononic switch based on ferroelectric domain walls: The ease with which domain walls (DWs) in ferroelectric materials can be\nwritten and erased provides a versatile way to dynamically modulate heat\nfluxes. In this work we evaluate the thermal boundary resistance (TBR) of\n180$^{\\circ}$ DWs in prototype ferroelectric perovskite PbTiO$_3$ within the\nnumerical formalisms of nonequilibrium molecular dynamics and nonequilibrium\nGreen's functions. An excellent agreement is obtained for the TBR of an\nisolated DW derived from both approaches, which reveals the harmonic character\nof the phonon-DW scattering mechanism. The thermal resistance of the\nferroelectric material is shown to increase up to around 20%, in the system\nsizes here considered, due to the presence of a single DW, and larger\nresistances can be attained by incorporation of more DWs along the path of\nthermal flux. These results, obtained at device operation temperatures, prove\nthe viability of an electrically actuated phononic switch based on\nferroelectric DWs.",
        "positive": "Fractional Marcus-Hush-Chidsey-Yakopcic current-voltage model for\n  redox-based resistive memory devices: We propose a circuit-level model combining the Marcus-Hush-Chidsey electron\ncurrent equation and the Yakopcic equation for the state variable for\ndescribing resistive switching memory devices of the structure metal-ionic\nconductor-metal. We extend the dynamics of the state variable originally\ndescribed by a first-order time derivative by introducing a fractional\nderivative with an arbitrary order between zero and one. We show that the\nextended model fits with great fidelity the current-voltage characteristic data\nobtained on a Si electrochemical metallization memory device with Ag-Cu alloy."
    },
    {
        "anchor": "Ultrafast Electron Dynamics in the Topological Insulator Bi2Se3 Studied\n  by Time-Resolved Photoemission Spectroscopy: We characterize the topological insulator Bi$_2$Se$_3$ using time- and angle-\nresolved photoemission spectroscopy. By employing two-photon photoemission, a\ncomplete picture of the unoccupied electronic structure from the Fermi level up\nto the vacuum level is obtained. We demonstrate that the unoccupied states host\na second, Dirac surface state which can be resonantly excited by 1.5 eV\nphotons. We then study the ultrafast relaxation processes following optical\nexcitation. We find that they culminate in a persistent non-equilibrium\npopulation of the first Dirac surface state, which is maintained by a\nmeta-stable population of the bulk conduction band. Finally, we perform a\ntemperature-dependent study of the electron-phonon scattering processes in the\nconduction band, and find the unexpected result that their rates decrease with\nincreasing sample temperature. We develop a model of phonon emission and\nabsorption from a population of electrons, and show that this counter-intuitive\ntrend is the natural consequence of fundamental electron-phonon scattering\nprocesses. This analysis serves as an important reminder that the decay rates\nextracted by time-resolved photoemission are not in general equal to single\nelectron scattering rates, but include contributions from filling and emptying\nprocesses from a continuum of states.",
        "positive": "Moisture-induced Damage Evolution in Laminated Beech: Structural elements made of laminated hardwood are increasingly used in\ntimber engineering. In this combined numerical and experimental approach,\ndamage onset and propagation in uni-directional and cross-laminated samples out\nof European beech due to climatic changes are studied. The inter- and\nintra-laminar damage evolution is characterized for various configurations\nadhesively bonded by three structural adhesive systems. Typical situations are\nsimulated by means of a comprehensive moisture-dependent non-linear rheological\nfinite element model for wood with the capability to capture delaminations. The\nsimulations give insight into the role of different strain components such as\nvisco-elastic, mechano-sorptive, plastic, and hygro-elastic deformations under\nchanging moisture content in progressive damage and delamination. We show the\nstress buildup under cyclic hygric loading resulting in hygro-fatigue and\nmodify an analytical micro-mechanics of damage model, originally developed for\ncross-ply laminates, to describe the problem of moisture-induced damage in\nbeech lamellae."
    },
    {
        "anchor": "CO oxidation on Pd(100) at technologically relevant pressure conditions:\n  A first-principles kinetic Monte Carlo study: The possible importance of oxide formation for the catalytic activity of\ntransition metals in heterogenous oxidation catalysis has evoked a lively\ndiscussion over the recent years. On the more noble transition metals (like Pd,\nPt or Ag) the low stability of the common bulk oxides suggests primarily\nsub-nanometer thin oxide films, so-called surface oxides, as potential\ncandidates that may be stabilized under gas phase conditions representative of\ntechnological oxidation catalysis. We address this issue for the Pd(100) model\ncatalyst surface with first-principles kinetic Monte Carlo (kMC) simulations\nthat assess the stability of the well-characterized (sqrt{5} x sqrt{5})R27\nsurface oxide during steady-state CO oxidation. Our results show that at\nambient pressure conditions the surface oxide is stabilized at the surface up\nto CO:O2 partial pressure ratios just around the catalytically most relevant\nstoichiometric feeds (p(CO):p(O2) = 2:1). The precise value depends sensitively\non temperature, so that both local pressure and temperature fluctuations may\ninduce a continuous formation and decomposition of oxidic phases during\nsteady-state operation under ambient stoichiometric conditions.",
        "positive": "Solvent-side observation on vibrational energy transfer by transient\n  grating spectroscopy: Bridged azulene-anthracene: Transient grating acoustic spectroscopy has been applied to studies on the\nvibrational energy relaxation process of the electronic ground state of\nazulene, two 1-alkylazulenes, and five bridged azulene-anthracenes in three\ndifferent solvents: 1,1,1-trichloro-1,2,2-trifluoroethane, acetonitrile, and\nxenon. The solute molecule was vibrationally excited by the photo-excitation of\nthe auzlenyl group to the S1 state through the fast internal conversion, and\nthe rate of solvent thermalization due to the vibrational energy relaxation was\ndetermined. The thermalization rates for 1-alkylazulenes and bridged\nazulene-anthracenes were faster than that of azulene. Based on the results of\nthe thermalization rates of 1-alkylazulenes, we concluded that the acceleration\nof the energy dissipation from the azulenyl group induced the faster energy\ndissipation from the solute to the solvent. The vibrational normal mode\nanalysis suggests that the density of the vibrational modes and anharmonic\ncoupling between the vibrational modes induce the faster intramolecular energy\nredistribution. In xenon, the solvent thermalization rates were close to the\nenergy dissipation rates of the solute molecule reported using transient\nabsorption spectroscopy. On the other hand, in the chlorofluorocarbon, the\nratio of the thermalization rate to the dissipation rate was a dependent of the\nmolecular species, and especially faster solvent thermalization rate of\n9-(6-(azulen-1-yl)hexyl)anthracene was predicted. The vibrational\ncharacteristics of this solvent are discussed in the relation to the\nvibrational modes and structures of the bridged compounds."
    },
    {
        "anchor": "Raman properties of GaSb nanoparticles embedded in SiO2 films: The Raman shifts of nanocrystalline GaSb excited by an Ar+ ion laser of\nwavelengths 514.5, 496.5, 488.0, 476.5, and 457.9 nm are studied by experiment\nand explained by phonon confinement, tensile stress, resonance Raman scattering\nand quantum size effects. The Stokes and anti-Stokes Raman spectra of GaSb\nnanocrystals strongly support the Raman feature of GaSb nanocrystals.\nCalculated optical spectra compare well with experimental data on Raman\nscattering GaSb nanocrystals.",
        "positive": "Core energy and regularization parameters of non-singular continuum\n  theories of dislocations using atomistic simulations: The dislocation core is an important region as it controls many important\nproperties of materials. Elasticity breaks down in the core and the stress,\nforce, and energy diverge at the dislocation line. We consider three commonest\nmethods employed in Discrete Dislocation Dynamics (DDD) simulations to\neliminate these singularities: (1) considering a cutoff parameter, (2)\nspreading the Burgers vector (CAWB theory), and (3) using gradient elasticity.\nEach of these methods includes an extra length parameter to regularize the\nelastic fields. In this article, we show that these regularization parameters\ncan significantly influence the results of the DDD simulations. We use\natomistic simulations for mixed dislocations to find the radius and energy of\nthe dislocation core and find the regularization parameter and its variations\nwith the dislocation character angle in each of the three methods. We have also\nconsidered if an arbitrary constant is chosen for the regularization parameter\nhow the core energy should be added to the simulation codes. We have concluded\nthat while the core energy in classical elasticity with a cutoff parameter can\nbe described by one parameter, the other two methods need two energy parameters\n(core energy of edge and core energy of screw) for describing the variation of\nthe core energy with the character angle. We have shown that no regularization\nparameter can be selected for the CAWB theory or gradient elasticity if no core\nenergy is included."
    },
    {
        "anchor": "Stability of Metallic Hydrogen at Ambient Conditions: The possibility of metallic hydrogen was first mooted by Wigner and\nHuntington in 1935. Here it is show that the calculations from that paper are\nin remarkably good agreement with modern density functional theory results. The\npossibility that metallic hydrogen could be recovered to ambient pressure is\noften attributed to papers by Brovman, although in fact they only say it would\nbe metastable with undetermined lifetime. Density functional theory\ncalculations presented here show that reasonable candidate structures for\nmetallic hydrogen are wildly unstable at ambient conditions, and molecular\ndynamics calculations show that the lifetime to which Brovman et al refer is\nconsiderably less than a picosecond. It is concluded that the prospects of\nusing recovered metallic hydrogen as rocket fuel or for electricity\ndistribution may have been overstated.",
        "positive": "Ab-initio investigation of phonon dispersion and anomalies in palladium: In recent years, palladium has proven to be a crucial component for devices\nranging from nanotube field effect transistors to advanced hydrogen storage\ndevices. In this work, I examine the phonon dispersion of fcc Pd using first\nprinciple calculations based on density functional perturbation theory. While\nseveral groups in the past have studied the acoustic properties of palladium,\nthis is the first study to reproduce the phonon dispersion and associated\nanomaly with high accuracy and no adjustable parameters. In particular, I focus\non the Kohn anomaly in the [110] direction."
    },
    {
        "anchor": "Tunable Ferromagnetism in LaCoO3 Epitaxial Thin Films: Ferromagnetic insulators play a crucial role in the development of\nlow-dissipation quantum magnetic devices for spintronics. Epitaxial LaCoO3 thin\nfilm is a prominent ferromagnetic insulator, in which the robust ferromagnetic\nordering emerges owing to epitaxial strain. Whereas it is evident that strong\nspin-lattice coupling induces ferromagnetism, the reported ferromagnetic\nproperties of epitaxially strained LaCoO3 thin films were highly consistent.\nFor example, even under largely modulated degree of strain, the reported Curie\ntemperatures of epitaxially strained LaCoO3 thin films lie within 80-85 K,\nwithout much deviation. In this study, substantial enhancement (~18%) in the\nCurie temperature of epitaxial LaCoO3 thin films is demonstrated via\ncrystallographic orientation dependence. By changing the crystallographic\norientation of the films from (111) to (110), the crystal-field energy was\nreduced and the charge transfer between the Co and O orbitals was enhanced.\nThese modifications led to a considerable enhancement of the ferromagnetic\nproperties (including the Curie temperature and magnetization), despite the\nidentical nominal degree of epitaxial strain. The findings of this study\nprovide insights into facile tunability of ferromagnetic properties via\nstructural symmetry control in LaCoO3.",
        "positive": "Tailoring Magnetism in Quantum Dots: We study magnetism in magnetically doped quantum dots as a function of\nconfining potential, particle numbers, temperature, and strength of Coulomb\ninteractions. We explore possibility of tailoring magnetism by controlling the\nelectron-electron Coulomb interaction, without changing the number of\nparticles. The interplay of strong Coulomb interactions and quantum confinement\nleads to enhanced inhomogeneous magnetization which persist at higher\ntemperatures than in the non-interacting case. The temperature of the onset of\nmagnetization can be controlled by changing the number of particles as well as\nby modifying the quantum confinement and the strength of Coulomb interactions.\nWe predict a series of electronic spin transitions which arise from the\ncompetition between the many-body gap and magnetic thermal fluctuations."
    },
    {
        "anchor": "Defect physics, delithiation mechanism, and electronic and ionic\n  conduction in layered lithium manganese oxide cathode materials: Layered LiMnO$_2$ and Li$_2$MnO$_3$ are of great interest for lithium-ion\nbattery cathodes because of their high theoretical capacities. The practical\napplication of these materials is, however, limited due to poor electrochemical\nperformance. We herein report a comprehensive first-principles study of defect\nphysics in LiMnO$_2$ and Li$_2$MnO$_3$ using hybrid-density functional\ncalculations. We find that manganese antisites have low formation energies in\nLiMnO$_2$ and may act as nucleation sites for the formation of impurity phases.\nThe antisites can also occur with high concentrations in Li$_2$MnO$_3$;\nhowever, unlike in LiMnO$_2$, they can be eliminated by tuning the experimental\nconditions during preparation. Other intrinsic point defects may also occur and\nhave an impact on the materials' properties and functioning. An analysis of the\nformation of lithium vacancies indicates that lithium extraction from LiMnO$_2$\nis associated with oxidation at the manganese site, resulting in the formation\nof manganese small hole polarons; whereas in Li$_2$MnO$_3$ the intrinsic\ndelithiation mechanism involves oxidation at the oxygen site, leading to the\nformation of bound oxygen hole polarons $\\eta_{\\rm O}^{+}$. The layered oxides\nare found to have no or negligible bandlike carriers and they cannot be doped\nn- or p-type. The electronic conduction proceeds through hopping of hole and/or\nelectron polarons; the ionic conduction occurs through lithium monovacancy\nand/or divacancy migration mechanisms. Since $\\eta_{\\rm O}^{+}$ is not stable\nin the absence of negatively charged lithium vacancies in bulk Li$_2$MnO$_3$,\nthe electronic conduction near the start of delithiation is likely to be poor.\nWe suggest that the electronic conduction associated with $\\eta_{\\rm O}^{+}$\nand, hence, the electrochemical performance of Li$_2$MnO$_3$ can be improved\nthrough nanostructuring and/or ion substitution.",
        "positive": "Structure of Magnetic Inhomogeneities in Films with Topological Features: This paper considers magnetic films with uniaxial anisotropy of the type\n\"easy plane\". It was found that in the presence of structural defects in such\nfilms, which are artificially created holes or non-magnetic inclusions,\nvortex-like inhomogeneities with a topological charge can form on them. Their\nstability is considered and it is shown in what cases (depending on the value\nand directions of currents, number of holes, etc.) they form stable\nconfigurations, suitable for information encoding.\n  --\n  V rabote rassmatrivajutsja magnitnye plenki s odnoosnoj anizotropiej tipa\n\"legkaja ploskost\". Ustanovleno, chto pri nalichii v takih plenkah strukturnyh\ndefektov, predstavljajushhih soboj iskusstvenno sozdannye otverstija ili\nnemagnitnye vkljuchenija, na nih mogut obrazovyvatsja vihrepodobnye\nneodnorodnosti, imejushhie topologicheskij zarjad. Rassmotrena ih ustojchivost\ni pokazano, v kakih sluchajah (v zavisimosti ot velichiny i napravlenija tokov,\nchisla otverstij i t.d.) oni obrazujut stabilnye konfiguracii, prigodnye dlja\nkodirovanija informacii."
    },
    {
        "anchor": "Hybrid, Gate-Tunable, van der Waals p-n Heterojunctions from Pentacene\n  and MoS2: The recent emergence of a wide variety of two-dimensional (2D) materials has\ncreated new opportunities for device concepts and applications. In particular,\nthe availability of semiconducting transition metal dichalcogenides, in\naddition to semi-metallic graphene and insulating boron nitride, has enabled\nthe fabrication of all 2D van der Waals heterostructure devices. Furthermore,\nthe concept of van der Waals heterostructures has the potential to be\nsignificantly broadened beyond layered solids. For example, molecular and\npolymeric organic solids, whose surface atoms possess saturated bonds, are also\nknown to interact via van der Waals forces and thus offer an alternative for\nscalable integration with 2D materials. Here, we demonstrate the integration of\nan organic small molecule p-type semiconductor, pentacene, with a 2D n-type\nsemiconductor, MoS2. The resulting p-n heterojunction is gate-tunable and shows\nasymmetric control over the anti-ambipolar transfer characteristic. In\naddition, the pentacene-MoS2 heterojunction exhibits a photovoltaic effect\nattributable to type II band alignment, which suggests that MoS2 can function\nas an acceptor in hybrid solar cells.",
        "positive": "Observation of an environmentally insensitive solid state spin defect in\n  diamond: Engineering coherent systems is a central goal of quantum science. Color\ncenters in diamond are a promising approach, with the potential to combine the\ncoherence of atoms with the scalability of a solid state platform. However, the\nsolid environment can adversely impact coherence. For example, phonon- mediated\nspin relaxation can induce spin decoherence, and electric field noise can\nchange the optical transition frequency over time. We report a novel color\ncenter with insensitivity to both of these sources of environmental\ndecoherence: the neutral charge state of silicon vacancy (SiV0). Through\ncareful material engineering, we achieve over 80% conversion of implanted\nsilicon to SiV0. SiV0 exhibits excellent spin properties, with spin-lattice\nrelaxation times (T1) approaching one minute and coherence times (T2)\napproaching one second, as well as excellent optical properties, with\napproximately 90% of its emission into the zero-phonon line and near-transform\nlimited optical linewidths. These combined properties make SiV0 a promising\ndefect for quantum networks."
    },
    {
        "anchor": "Speeding up high-throughput characterization of materials libraries by\n  active learning: autonomous electrical resistance measurements: High-throughput experimentation enables efficient search space exploration\nfor the discovery and optimization of new materials. However, large search\nspaces of, e.g., compositionally complex materials, require decreasing\ncharacterization times significantly. Here, an autonomous measurement algorithm\nwas developed, which leverages active learning based on a Gaussian process\nmodel capable of iteratively scanning a materials library based on the highest\nuncertainty. The algorithm is applied to a four-point probe electrical\nresistance measurement device, frequently used to obtain indications for\nregions of interest in materials libraries. Ten materials libraries with\ndifferent complexities of composition and property trends are analyzed to\nvalidate the model. By stopping the process before the entire library is\ncharacterized and predicting the remaining measurement areas, the measurement\nefficiency can be improved drastically. As robustness is essential for\nautonomous measurements, intrinsic outlier handling is built into the model and\na dynamic stopping criterion based on the mean predicted covariance is\nproposed. A measurement time reduction of about 70-90% was observed while still\nensuring an accuracy of above 90%.",
        "positive": "Electron-phonon scattering in quantum wires exposed to a normal magnetic\n  field: A theory for the relaxation rates of a test electron and electron temperature\nin quantum wires due to deformation, piezoelectric acoustical and polar optical\nphonon scattering is presented. We represent intra- and inter-subband\nrelaxation rates as an average of rate kernels weighted by electron wave\nfunctions across a wire. We exploit these expressions to calculate phonon\nemission power for electron intra- and inter-subband transitions in quantum\nwires formed by a parabolic confining potential. In a magnetic field free case\nwe have calculated the emission power of acoustical (deformation and\npiezoelectric interaction) and polar optical phonons as a function of the\nelectron initial energy for different values of the confining potential\nstrength. In quantum wires exposed to the quantizing magnetic field normal to\nthe wire axis, we have calculated the polar optical phonon emission power as a\nfunction of the electron initial energy and of the magnetic field."
    },
    {
        "anchor": "Assessment of correlation energies based on the random-phase\n  approximation: The random-phase approximation to the ground state correlation energy (RPA)\nin combination with exact exchange (EX) has brought Kohn-Sham (KS) density\nfunctional theory one step closer towards a universal, \"general purpose first\nprinciples method\". In an effort to systematically assess the influence of\nseveral correlation energy contributions beyond RPA, this work presents\ndissociation energies of small molecules and solids, activation energies for\nhydrogen transfer and non-hydrogen transfer reactions, as well as reaction\nenergies for a number of common test sets. We benchmark EX+RPA and several\nflavors of energy functionals going beyond it: second-order screened exchange\n(SOSEX), single excitation (SE) corrections, renormalized single excitation\n(rSE) corrections, as well as their combinations. Both the single excitation\ncorrection as well as the SOSEX contribution to the correlation energy\nsignificantly improve upon the notorious tendency of EX+RPA to underbind.\nSurprisingly, activation energies obtained using EX+RPA based on a KS reference\nalone are remarkably accurate. RPA+SOSEX+rSE provides an equal level of\naccuracy for reaction as well as activation energies and overall gives the most\nbalanced performance, which makes it applicable to a wide range of systems and\nchemical reactions.",
        "positive": "The Inherent Behavior of Graphene Flakes in Water: A Molecular Dynamics\n  Study: Graphene-water interaction has been under scrutiny ever since graphene\ndiscovery and realization of its exceptional properties. Several computational\nand experimental reports exist that have tried to look into the interactions\ninvolved, however, none of them addresses the issue in its entirety. We have\ntested the inherent hydrophobic behavior of a small graphene in water droplet\nby the means of MD simulations. The analysis has been extended to multiple\ngraphene flakes in water and their respective size dependent responses to water\ndroplet. Graphene retreats from water droplet to encapsulate it from the\nsurface. This response was highly dependent upon graphene size with respect to\nwater content. Additionally, we also report self-assembly of multilayered\ngraphene in water by means of MD simulations, an observation which can be\nutilized to synthesize such structures in a cost-effective way by\nexperimentalists. To fully comprehend graphene behavior in water, graphene\ndeformation was analyzed in the presence of water molecules. It was noticed\nthat graphene wrinkled to wrap around water molecules and resisted complete\nfailure, one that is seen in case of a sole graphene sheet. Our work will not\nonly address the question about whether graphene is hydrophobic or hydrophilic\nbut also provide insight into the behavior of graphene surface and mobility\nwhen exposed to water which can be exploited in numerous applications."
    },
    {
        "anchor": "Molecular Beam Study of the CO Adsorption on a Regular Array of PdAu\n  Clusters on Alumina: The adsorption kinetics of CO on PdAu bimetallic clusters, containing 140\n$\\pm$ 12 atoms and a composition varying between 0% and 55% of Pd atoms, is\ninvestigated by a pulsed molecular beam method (MBRS). The clusters are grown\non a nanostructured ultrathin film of alumina on Ni3Al (111) playing the role\nof a template which gives a hexagonal array of bimetallic clusters having a\nsharp size distribution and a uniform composition. The surface concentration\ncalculated, assuming segregation of gold to the surface, varies between 0 and\n90% of Au atoms on the surface. From the adsorption-desorption kinetics of CO,\nthe lifetime of CO is measured at various temperatures. At low coverage,\nplotting the CO lifetime in an Arrhenius diagram one obtains the adsorption\nenergy of CO. When the surface concentration of Au increases, the adsorption\nenergy of CO on the PdAu clusters decreases. This evolution of the adsorption\nenergy is discussed, from previous studies, in term of ligand and ensemble\neffects. We find that the ensemble effect plays a dominant role in the observed\ndecrease of the adsorption energy of CO.",
        "positive": "Perovskite-perovskite tandem photovoltaics with optimized bandgaps: We demonstrate four and two-terminal perovskite-perovskite tandem solar cells\nwith ideally matched bandgaps. We develop an infrared absorbing 1.2eV bandgap\nperovskite, $FA_{0.75}Cs_{0.25}Sn_{0.5}Pb_{0.5}I_3$, that can deliver 14.8 %\nefficiency. By combining this material with a wider bandgap\n$FA_{0.83}Cs_{0.17}Pb(I_{0.5}Br_{0.5})_3$ material, we reach monolithic two\nterminal tandem efficiencies of 17.0 % with over 1.65 volts open-circuit\nvoltage. We also make mechanically stacked four terminal tandem cells and\nobtain 20.3 % efficiency. Crucially, we find that our infrared absorbing\nperovskite cells exhibit excellent thermal and atmospheric stability,\nunprecedented for Sn based perovskites. This device architecture and materials\nset will enable 'all perovskite' thin film solar cells to reach the highest\nefficiencies in the long term at the lowest costs."
    },
    {
        "anchor": "Highly ordered lead-free double perovskite halides by design: Lead-free double perovskite halides are emerging optoelectronic materials\nthat are alternatives to lead-based perovskite halides. Recently,\nsingle-crystalline double perovskite halides were synthesized, and their\nintriguing functional properties were demonstrated. Despite such pioneering\nworks, lead-free double perovskite halides with better crystallinity are still\nin demand for applications to novel optoelectronic devices. Here, we realized\nhighly crystalline Cs2AgBiBr6 single crystals with a well-defined atomic\nordering on the microscopic scale. We avoided the formation of Ag vacancies and\nthe subsequent secondary Cs3Bi2Br9 by manipulating the initial chemical\nenvironments in hydrothermal synthesis. The suppression of Ag vacancies allows\nus to reduce the trap density in the as-grown crystals and to enhance the\ncarrier mobility further. Our design strategy is applicable for fabricating\nother lead-free halide materials with high crystallinity.",
        "positive": "Structural, Surface Morphology and Magneto-Transport properties of Self\n  Flux Grown Eu Doped Bi2Se3 Single Crystal: Here, we report the effect of europium (Eu) doping in Bi2Se3 topological\ninsulator (TI) by using different characterization techniques viz. X-ray\ndiffraction (XRD), scanning electron microscopy (SEM) coupled with energy\ndispersive X-ray analysis (EDXA) and magneto-transport measurements.\nTemperature dependent electrical resistivity curves revealed a metallic\nbehaviour both in the presence and absence of applied magnetic field.\nMagneto-transport measurements showed a decrease in the magneto-resistance (MR)\nvalue of the Eu0.1Bi1.9Se3 sample (32% at 5K) in comparison to the pure Bi2Se3\nsample (80% at 5K). For, Eu0.1Bi1.9Se3 sample, a complex crossover between WL\nand WAL phenomenon was observed at lower applied magnetic fields, whereas the\nsame was absent in case of the pristine one. Further, HLN (Hikami Larkin\nNagaoka) fitted magneto-conductivity (MC) analysis revealed a competing weak\nanti localization (WAL) and weak localization (WL) behaviour. Summarily, in the\npresent work we study the structural, surface morphology and magneto-transport\nproperties of as grown Eu0.1Bi1.9Se3 single crystals."
    },
    {
        "anchor": "Molecular Dysprosium Complexes for White-Light and Near-Infrared\n  Emission Controlled by the Coordination Environment: A series of single-molecule dysprosium (Dy 3+) complexes consisting of b\ndiketonate ligands, as water-containing complexes, and the auxiliary\ntriphenylphosphine oxide (tppo)ligand as water free complexes were investigated\nas potential white light emitters. The coordination environment and choice of\nthe ligands play an important role in the behavior of the yellow and blue\nemission of the Dy 3+ complexes based on the sensitization efficiency of the Dy\n3+ ion by the ligands. By introducing the auxiliary tppo ligand in the complex,\nthe relative intensity of the Dy 3+ emission increases due to a more efficient\nsensitization of the Dy 3+ ion.",
        "positive": "Zero-Point Quantum Diffusion of Proton in Hydrogen-rich Superconductor\n  $LaH_{10}$: $LaH_{10}$, as a member of hydrogen-rich superconductors, has a\nsuperconducting critical temperature of 250 K at high pressures, which exhibits\nthe possibility of solving the long-term goal of room temperature\nsuperconductivity. Considering the extreme pressure and low mass of hydrogen,\nthe nuclear quantum effects in $LaH_{10}$ should be significant and have an\nimpact on its various physical properties. Here, we adopt the method combines\ndeep-potential (DP) and quantum thermal bath (QTB), which was verified to be\nable to account for quantum effects in high-accuracy large-scale molecular\ndynamics simulations. Our method can actually reproduce pressure-temperature\nphase diagrams of $LaH_{10}$ consistent with experimental and theoretical\nresults. After incorporating quantum effects, the quantum fluctuation driven\ndiffusion of proton is found even in the absence of thermal fluctuation near 0\nK. The high mobility of proton is found to be compared to liquid, yet the\nstructure of $LaH_{10}$ is still rigid. These results would greatly enrich our\nvision to study quantum behavior of hydrogen-rich superconductors."
    },
    {
        "anchor": "Interplay between local moment and itinerant magnetism in the layered\n  metallic antiferromagnet TaFe$_{1.14}$Te$_3$: Two-dimensional (2D) antiferromagnets have garnered considerable interest for\nthe next generation of functional spintronics. However, many available bulk\nmaterials from which 2D antiferromagnets are isolated are limited by their\nsensitivity to air, low ordering temperatures, and insulating transport\nproperties. TaFe$_{1+y}$Te$_3$ offers unique opportunities to address these\nchallenges with increased air stability, metallic transport properties, and\nrobust antiferromagnetic order. Here, we synthesize TaFe$_{1+y}$Te$_3$ ($y$ =\n0.14), identify its structural, magnetic, and electronic properties, and\nelucidate the relationships between them. Axial-dependent high-field\nmagnetization measurements on TaFe$_{1.14}$Te$_3$ reveal saturation magnetic\nfields ranging between 27-30 T with a saturation magnetic moment of 2.05-2.12\n$\\mu_B$. Magnetotransport measurements confirm TaFe$_{1.14}$Te$_3$ is metallic\nwith strong coupling between magnetic order and electronic transport.\nAngle-resolved photoemission spectroscopy measurements across the magnetic\ntransition uncover a complex interplay between itinerant electrons and local\nmagnetic moments that drives the magnetic transition. We further demonstrate\nthe ability to isolate few-layer sheets of TaFe$_{1.14}$Te$_3$ through\nmechanical exfoliation, establishing TaFe$_{1.14}$Te$_3$ as a potential\nplatform for 2D spintronics based on metallic layered antiferromagnets.",
        "positive": "Enhanced sputtering and incorporation of Mn in implanted GaAs and ZnO\n  nanowires: We simulated and experimentally investigated the sputter yield of ZnO and\nGaAs nanowires, which were implanted with energetic Mn ions at room\ntemperature. The resulting thinning of the nanowires and the dopant\nconcentration with increasing Mn ion fluency were measured by accurate scanning\nelectron microscopy (SEM) and nano-X-Ray Fluorescence (nanoXRF) quantification,\nrespectively. We observed a clear enhanced sputter yield for the irradiated\nnanowires compared to bulk, which is also corroborated by iradina simulations.\nThese show a maximum if the ion range matches the nanowire diameter. As a\nconsequence of the erosion thinning of the nanowire, the incorporation of the\nMn dopants is also enhanced and increases non-linearly with increasing ion\nfluency."
    },
    {
        "anchor": "Hidden Symmetry and Mutiferroicity in a Triangular Spin Lattice With\n  Proper-Screw-Spin Chain Order: The multiferroicity in a triangular spin lattice with proper-screw-spin chain\norder was explored by performing density functional calculations for AgCrO2 and\nanalyzing the symmetry of the magnetic structure of the triangular spin\nlattice. Strong geometric spin frustration exists within and between CrO2\nlayers, and the ferroelectric polarization originates from the spiral-spin\nchain structures propagating across the proper-screw-spin chains. The\ntriangular spin lattice can have ferroelectric polarization parallel to its\nmirror plane due to hidden symmetry.",
        "positive": "Atomistic Model Potential for PbTiO3 and PMN by Fitting First Principles\n  Results: We have developed a shell model potential to describe PbTiO3 and\nPbMg1/3Nb2/3O3 (PMN) by fitting to first-principles results. At zero pressure,\nthe model reproduces the temperature behavior of PbTiO3, but with a smaller\ntransition temperature than experimentally observed. We then fit a shell model\npotential for the complex PMN based on the transferability of the interatomic\npotentials. We find that even for ordered PMN, quenching the structure gives a\nnon-polar state, but with local polarization (off-center ions) indicative of\nrelaxor behavior."
    },
    {
        "anchor": "Dislocation constriction and cross-slip in Al and Ag: an ab initio study: A novel model based on the Peierls framework of dislocations is developed.\nThe new theory can deal with a dislocation spreading at more than one slip\nplanes. As an example, we study dislocation cross-slip and constriction process\nof two fcc metals, Al and Ag. The energetic parameters entering the model are\ndetermined from ab initio calculations. We find that the screw dislocation in\nAl can cross-slip spontaneously in contrast with that in Ag, which splits into\npartials and cannot cross-slip without first being constricted. The dislocation\nresponse to an external stress is examined in detail. We determine dislocation\nconstriction energy and critical stress for cross-slip, and from the latter, we\nestimate the cross-slip energy barrier for the straight screw dislocations.",
        "positive": "Hydrogen Dissociation and Diffusion on Transition\n  Metal(=Ti,Zr,V,Fe,Ru,Co,Rh,Ni,Pd,Cu,Ag)-doped Mg(0001) Surfaces: The kinetics of hydrogen absorption by magnesium bulk is affected by two main\nactivated processes: the dissociation of the H$_2$ molecule and the diffusion\nof atomic H into the bulk. In order to have fast absorption kinetics both\nactivated processed need to have a low barrier. Here we report a systematic\nab-initio density functional theory investigation of H$_2$ dissociation and\nsubsequent atomic H diffusion on TM(=Ti,V,Zr,Fe,Ru,Co,Rh,Ni,Pd,Cu,Ag)-doped\nMg(0001) surfaces. The calculations show that doping the surface with TM's on\nthe left of the periodic table eliminates the barrier for the dissociation of\nthe molecule, but the H atoms bind very strongly to the TM, therefore hindering\ndiffusion. Conversely, TM's on the right of the periodic table don't bind H,\nhowever, they do not reduce the barrier to dissociate H$_2$ significantly. Our\nresults show that Fe, Ni and Rh, and to some extent Co and Pd, are all\nexceptions, combining low activation barriers for both processes, with Ni being\nthe best possible choice."
    },
    {
        "anchor": "Anisotropic Topological Hall Effect with Real and Momentum Space Berry\n  Curvature in the Antiskrymion Hosting Heusler Compound Mn$_{1.4}$PtSn: The topological Hall effect (THE) is one of the key signatures of\ntopologically non-trivial magnetic spin textures, wherein electrons feel an\nadditional transverse voltage to the applied current. The magnitude of THE is\noften small compared to the anomalous Hall effect. Here, we find a large THE of\n0.9 $\\mu\\Omega$cm that is of the same order of the anomalous Hall effect in the\nsingle crystalline antiskyrmion hosting Heusler compound Mn$_{1.4}$PtSn, a\nnon-centrosymmetric tetragonal compound. The THE is highly anisotropic and\nsurvives in the whole temperature range where the spin structure is noncoplanar\n(<170 K). The THE is zero above the spin reorientation transition temperature\nof 170 K, where the magnetization will have a collinear and ferromagnetic\nalignment. The large value of the THE entails a significant contribution from\nthe momentum space Berry curvature along with real space Berry curvature, which\nhas never been observed earlier.",
        "positive": "The FHI-aims Code: All-electron, ab initio materials simulations towards\n  the exascale: FHI-aims is a quantum mechanics software package based on numeric\natom-centered orbitals (NAOs) with broad capabilities for all-electron\nelectronic-structure calculations and ab initio molecular dynamics. It also\nconnects to workflows for multi-scale and artificial intelligence modeling."
    },
    {
        "anchor": "The Robustness of Cluster Expansion: Assessing the Roles of Relaxation\n  and Numerical Error: Cluster expansion (CE) is effective in modeling the stability of metallic\nalloys, but sometimes cluster expansions fail. Failures are often attributed to\natomic relaxation in the DFT-calculated data, but there is no metric for\nquantifying the degree of relaxation. Additionally, numerical errors can also\nbe responsible for slow CE convergence. We studied over one hundred different\nHamiltonians and identified a heuristic, based on a normalized mean-squared\ndisplacement of atomic positions in a crystal, to determine if the effects of\nrelaxation in CE data are too severe to build a reliable CE model. Using this\nheuristic, CE practitioners can determine a priori whether or not an alloy\nsystem can be reliably expanded in the cluster basis. We also examined the\nerror distributions of the fitting data. We find no clear relationship between\nthe type of error distribution and CE prediction ability, but there are clear\ncorrelations between CE formalism reliability, model complexity, and the number\nof significant terms in the model. Our results show that the \\emph{size} of the\nerrors is much more important than their distribution.",
        "positive": "A rigorous two-dimensional model for the stripline ferromagnetic\n  resonance response of metallic ferromagnetic films: In this work we constructed a two-dimensional numerical model for calculation\nof the stripline ferromagnetic resonance (FMR) response of metallic\nferromagnetic films. We also conducted numerical calculations by using this\nsoftware. The calculations demonstrated that the eddy current contribution to\nthe FMR response decreases with a decrease in the stripline width. The most\nimportant manifestations of the conductivity (eddy current) effect are\nexcitation of the higher-order standing spin waves across the film thickness in\nthe materials for which the standing spin wave peaks would be absent in cavity\nFMR measurements and strong dependence of the off-resonance series conductance\nof the stripline on the stripline width. Whereas the contribution of the eddy\ncurrents to the stripline FMR response can be very significant, because wide\nstriplines (100nm+) are conventionally used for the FMR measurements, it is\nnegligible in the case of excitation of spin waves, just because very narrow\nstripline transducers (0.5-5micron wide) are required in order to excite spin\nwaves in metallic ferromagnetic films in a noticeable frequency/applied field\nrange."
    },
    {
        "anchor": "The Effect of Temperature on Cu-K-In-Se Thin Films: Films of Cu-K-In-Se were co-evaporated at varied K/(K+Cu) compositions and\nsubstrate temperatures (with constant (K+Cu)/In ~ 0.85). Increased Na\ncomposition on the substrate's surface and decreased growth temperature were\nboth found to favor Cu1-xKxInSe2 (CKIS) alloy formation, relative to\nmixed-phase CuInSe2 + KInSe2 formation. Structures from X-ray diffraction\n(XRD), band gaps, resistivities, minority carrier lifetimes and carrier\nconcentrations from time-resolved photoluminescence were in agreement with\nprevious reports, where low K/(K+Cu) composition films exhibited properties\npromising for photovoltaic (PV) absorbers. Films grown at 400-500 C were then\nannealed to 600 C under Se, which caused K loss by evaporation in proportion to\ninitial K/(K+Cu) composition. Similar to growth temperature, annealing drove\nCKIS alloy consumption and CuInSe2 + KInSe2 production, as evidenced by high\ntemperature XRD. Annealing also decomposed KInSe2 and formed K2In12Se19. At\nhigh temperature the KInSe2 crystal lattice gradually contracted as temperature\nand time increased, as well as just time. Evaporative loss of K during\nannealing could accompany the generation of vacancies on K lattice sites, and\nmay explain the KInSe2 lattice contraction. This knowledge of Cu-K-In-Se\nmaterial chemistry may be used to predict and control minor phase impurities in\nCu(In,Ga)(Se,S)2 PV absorbers-where impurities below typical detection limits\nmay have played a role in recent world record PV efficiencies that utilized KF\npost-deposition treatments.",
        "positive": "Temperature-Dependent Resistivity of Alternative Metal Thin Films: The temperature coefficients of the resistivity (TCR) of Cu, Ru, Co, Ir, and\nW thin films have been investigated as a function of film thickness below 10\nnm. Ru, Co, and Ir show bulk-like TCR values that are rather independent of the\nthickness whereas the TCR of Cu increases strongly with decreasing thickness.\nThin W films show negative TCR values, which can be linked to high disorder.\nThe results are qualitatively consistent with a temperature-dependent\nsemiclassical thin film resistivity model that takes into account phonon,\nsurface, and grain boundary scattering."
    },
    {
        "anchor": "Unusual $^{209}$Bi NMR quadrupole effects in topological insulator\n  Bi$_2$Se$_3$: Three-dimensional topological insulators are an important class of modern\nmaterials, and a strong spin-orbit coupling is involved in making the bulk\nelectronic states very different from those near the surface. Bi$_2$Se$_3$ is a\nmodel compound, and $^{209}$Bi NMR is employed here to investigate the bulk\nproperties of the material with focus on the quadrupole splitting. It will be\nshown that this splitting measures the energy band inversion induced by\nspin-orbit coupling in quantitative agreement with first-principle\ncalculations. Furthermore, this quadrupole interaction is very unusual as it\ncan show essentially no angular dependence, e.g., even at the magic angle the\nfirst-order splitting remains. Therefore, it is proposed that the magnetic\nfield direction is involved in setting the quantization axis for the electrons,\nand that their life time leads to a new electronically driven relaxation\nmechanism, in particular for quadrupolar nuclei like $^{209}$Bi. While a\nquantitative understanding of these effects cannot be given, the results\nimplicate that NMR can become a powerful tool for the investigation of such\nsystems.",
        "positive": "Making Consistent Contacts to Graphene: Effect of Architecture and\n  Growth Induced Defects: The effect of contact architecture, graphene defect density and\nmetal-semiconductor work function difference on resistivity of metal-graphene\ncontacts have been investigated. An architecture with metal on the bottom of\ngraphene is found to yield resistivities that are lower, by a factor of 4, and\nmost consistent as compared to metal on top of graphene. Growth defects in\ngraphene film were found to further reduce resistivity by a factor of 2. Using\na combination of method and metal used, the contact resistivity of graphene has\nbeen decreased by a factor of 10 to 1200 +- 250 Ohm-um using Palladium as the\ncontact metal. While the improved consistency is due to the metal being able to\ncontact uncontaminanted graphene in the metal on the bottom architecture, lower\ncontact resistivities observed on defective graphene with the same metal is\nattributed to the increased number of modes of quantum transport in the\nchannel."
    },
    {
        "anchor": "Triclinic Ni0.6Co0.4TiO3 Ilmenite Oxide: Forming a solid-solution of NiTiO3 and CoTiO3, two isostructural (ilmenite)\nand isosymmetrical (space group R-3) compounds, result in a single-phase\ncompound with a remarkably low crystal symmetry. By neutron and X-ray\nsynchrotron powder diffraction techniques, the space group symmetry of the\nNi0.6Co0.4TiO3 sample was found to be triclinic P-1 at room temperature, far\nabove the magnetic transition temperature. Ni and Co ions were found to prefer\npositions close to the octahedron center, whereas Ti ions took off-center\npositions. This structural distortion is the first known case in ilmenites and\nopens up ways to modify functional properties of magnetic oxides. Origin of the\nsymmetry lowering is discussed.",
        "positive": "Facile synthesis of 2D graphene oxide sheet enveloping ultrafine 1D\n  LiMn2O4 as interconnected framework to enhance cathodic property for Li-ion\n  battery: Cubic spinel lithium manganese oxide (LiMn2O4) has been able to attract a\ngreat deal of attention over the years as a promising cathode material for\nlarge scale lithium ion batteries. Here a facile hydrothermal route followed by\nsolid state reaction is developed using as grown ultrafine alpha-MnO2 nanorods\nto prepare one dimensional LiMn2O4 with 10-50nm diameters. To enhance the\ncathodic property of these nanorods, a unique synthesis technique of heat\ntreatment is developed to grow 2D graphene oxide sheet enveloping 1D LiMn2O4 as\ninterconnected framework. This nanocomposite 3D porous cathode exhibits a high\nspecific charge capacity of 130mAh/g at 0.05C rate and Coulombic efficiency of\nabout 98% after 100 cycles in the potential window of 3.5 to 4.3V versus Li/Li+\nwith promising initial charge capacity retention of about 87%, and outstanding\nstructural stability even after 100 cycles. Enhancement in the lithiation and\ndelithiation processes leading to improved performance is likely to have its\norigin in the 2D conducting graphene oxide sheets. It allows for decreasing the\nMn dissolution, improve the electron conductivity and reduce the Li-ion path\ndiffusion inside the favourable morphology and crystallinity of the ultrafine\n1D LiMn2O4 nanorods, giving rise to a promising cathode nanocomposite."
    },
    {
        "anchor": "Growth Mechanisms and Oxidation-Resistance of Gold-Coated Iron\n  Nanoparticles: We report the chemical synthesis of Fe-core/Au-shell nanoparticles by a\nreverse micelle method, and the investigation of their growth mechanisms and\noxidation-resistant characteristics. The core-shell structure and the presence\nof the Fe & Au phases have been confirmed by transmission electron microscopy,\nenergy dispersive spectroscopy, X-ray diffraction, Mossbauer spectroscopy, and\ninductively coupled plasma techniques. Additionally, atomic-resolution\nZ-contrast imaging and electron energy loss spectroscopy (EELS) in a scanning\ntransmission electron microscope (STEM) have been used to study details of the\ngrowth processes. The Au-shell grows by nucleating on the Fe-core surface\nbefore coalescing. The magnetic moments of such nanoparticles, in the loose\npowder form, decrease over time due to oxidation. The less than ideal\noxidation-resistance of the Au shell may have been caused by the rough Au\nsurfaces. However, in the pressed pellet form, electrical transport\nmeasurements show that the particles are fairly stable, as the resistance of\nthe pellet does not change appreciably over time.",
        "positive": "Damage accumulation during high temperature fatigue of Ti/SiC$_f$ metal\n  matrix composites under different stress amplitudes: The damage mechanisms and load redistribution of high strength TC17 titanium\nalloy/unidirectional SiC fibre composite (fibre diameter = 100 $\\mu$m) under\nhigh temperature (350 {\\deg}C) fatigue cycling have been investigated in situ\nusing synchrotron X-ray computed tomography (CT) and X-ray diffraction (XRD)\nfor high cycle fatigue (HCF) under different stress amplitudes. The\nthree-dimensional morphology of the crack and fibre fractures has been mapped\nby CT. During stable growth, matrix cracking dominates with the crack\ndeflecting (by 50-100 $\\mu$m in height) when bypassing bridging fibres. A small\nnumber of bridging fibres have fractured close to the matrix crack plane\nespecially under relatively high stress amplitude cycling. Loading to the peak\nstress led to rapid crack growth accompanied by a burst of fibre fractures.\nMany of the fibre fractures occurred 50-300 $\\mu$m from the matrix crack plane\nduring rapid growth, in contrast to that in the stable growth stage, leading to\nextensive fibre pull-out on the fracture surface. The changes in fibre loading,\ninterfacial stress, and the extent of fibre-matrix debonding in the vicinity of\nthe crack have been mapped for the fatigue cycle and after the rapid growth by\nhigh spatial resolution XRD. The fibre/matrix interfacial sliding extends up to\n600 $\\mu$m (in the stable growth zone) or 700 $\\mu$m (in the rapid growth zone)\neither side of the crack plane. The direction of interfacial shear stress\nreverses with the loading cycle, with the maximum frictional sliding stress\nreaching ~55 MPa in both the stable growth and rapid growth regimes."
    },
    {
        "anchor": "Adsorption configurations of Co-phthalocyanine on In2O3(111): Indium oxide offers optical transparency paired with electric conductivity, a\ncombination required in many optoelectronic applications. The most-stable\nIn2O3(111) surface has a large unit cell (1.43 nm lattice constant). It\ncontains a mixture of both bulk-like and undercoordinated O and In atoms and\nprovides an ideal playground to explore the interaction of surfaces with\norganic molecules of similar size as the unit cell. Non-contact atomic force\nmicroscopy (nc-AFM), scanning tunneling microscopy (STM), and density\nfunctional theory (DFT) were used to study the adsorption of Co-phthalocyanine\n(CoPc) on In2O3(111). Isolated CoPc molecules adsorb at two adsorption sites in\na 7:3 ratio. The Co atom sits either on top of a surface oxygen ('F\nconfiguration') or indium atom ('S configuration'). This subtle change in\nadsorption site induces bending of the molecules, which is reflected in their\nelectronic structure. According to DFT the lowest unoccupied molecular orbital\nof the undistorted gas-phase CoPc remains mostly unaffected in the F\nconfiguration but is filled by one electron in S configuration. At coverages up\nto one CoPc molecule per substrate unit cell, a mixture of domains with\nmolecules in F and S configuration are found. Molecules at F sites first\ncondense into a F-(2x2) structure and finally rearrange into a F-(1x1) symmetry\nwith partially overlapping molecules, while S-sited molecules only assume a\nS-(1x1) superstructure.",
        "positive": "Electron-phonon couplings inherent in polarons drive exciton dynamics in\n  two-dimensional metal-halide perovskites: We report on the exciton formation and relaxation dynamics following\nphotocarrier injection in a single-layer two-dimensional lead-iodide\nperovskite. We probe the time evolution of four distinct exciton resonances by\nmeans of time-resolved photoluminescence and transient absorption\nspectroscopies, and find that at 5\\,K a subset of excitons form on a $\\lesssim$\n1-ps timescale, and that these relax subsequently to lower-energy excitons on\n$\\sim$ 5--10\\,ps with a marked temperature dependence over $<$ 100\\,K. We\nimplement a mode projection analysis that determines the relative contribution\nof all observed phonons with frequency $\\leq$50\\,cm$^{-1}$ to inter-exciton\nnonadiabatic coupling, which in turn determines the rate of exciton relaxation.\nThis analysis ranks the relative contribution of the phonons that participate\nin polaronic lattice distortions to the exciton inter-conversion dynamics and\nthus establishes their role in the nonadiabatic mixing of exciton states, and\nthis in the exciton relaxation rate."
    },
    {
        "anchor": "X-ray interference effects on the determination of structural data in\n  ultrathin La2/3Sr1/3MnO3 epitaxial thin films: We analyze X-ray diffraction data used to extract cell parameters of\nultrathin films on closely matching substrates. We focus on epitaxial\nLa2/3Sr1/3MnO3 films grown on (001) SrTiO3 single crystalline substrates. It\nwill be shown that, due to extremely high structural similarity of film and\nsubstrate, data analysis must explicitly consider the distinct phase of the\ndiffracted waves by substrate and films to extract reliable unit cell\nparameters. The implications of this finding for the understanding of strain\neffects in ultrathin films and interfaces will be underlined",
        "positive": "Colossal magnetocapacitive effect in differently synthesized and doped\n  CdCr2S4: In the present work, we address the question of an impurity-related origin of\nthe colossal magnetocapacitive effect in the spinel system CdCr2S4. We\ndemonstrate that a strong variation in the dielectric constant below the\nmagnetic transition temperature or in external magnetic fields also arises in\ncrystals prepared without chlorine. This excludes that an inhomogeneous\ndistribution of chlorine impurities at the surface or in the bulk material\ngives rise to the unusual effects in the spinel multiferroics. In addition, we\nshow that colossal magnetocapacitive effects can be also generated in\nchlorine-free ceramic samples of CdCr2S4, doped with indium."
    },
    {
        "anchor": "Morphological instabilities of a thin film on a Penrose lattice: a Monte\n  Carlo study: We computed by a Monte Carlo method the thermal relaxation of a\npolycrystalline thin film deposited on a Penrose lattice. The thin film was\nmodelled by a 2 dimensional array of elementary domains, which have each a\ngiven height. During the Monte Carlo process, the height of each of these\nelementary domains is allowed to change as well as their crystallographic\norientation. After equilibrium is reached at a given numerical temperature, all\nelementary domains have changed their orientation into the same one and small\nislands appear, preferentially on the domains of the Penrose lattice located in\nthe center of heptagons. This method is a new numerical approach to study the\ninfluence of the substrate and its defects on the islanding process of\npolycrystalline films.",
        "positive": "High Mobility in a Stable Transparent Perovskite Oxide: We discovered that La-doped BaSnO3 with the perovskite structure has an\nunprecedentedly high mobility at room temperature while retaining its optical\ntransparency. In single crystals, the mobility reached 320 cm^2(Vs)^-1 at a\ndoping level of 8x10^19 cm^-3, constituting the highest value among\nwide-band-gap semiconductors. In epitaxial films, the maximum mobility was 70\ncm^2(Vs)^-1 at a doping level of 4.4x10^20 cm^-3. We also show that resistance\nof (Ba,La)SnO3 changes little even after a thermal cycle to 530 Deg. C in air,\npointing to an unusual stability of oxygen atoms and great potential for\nrealizing transparent high-frequency, high-power functional devices."
    },
    {
        "anchor": "Direct evidence of enhanced Ga interdiffusion in InAs vertically aligned\n  free-standing nanowires: We present direct evidence of enhanced Ga interdiffusion in InAs\nfree-standing nanowires grown at moderate temperatures by molecular beam\nepitaxy on GaAs (111)B. Scanning electron microscopy together with X-ray\ndiffraction measurements in coplanar and grazing incidence geometries show that\nnominally grown InAs NWs are actually made of In$_{0.86}$Ga$_{0.14}$As. Unlike\ntypical vapor-liquid-solid growth, these nanowires are formed by\ndiffusion-induced growth combined with strong interdiffusion from substrate\nmaterial. Based on the experimental results, a simple nanowire growth model\naccounting for the Ga interdiffusion is also presented. This growth model could\nbe generally applicable to the molecular beam heteroepitaxy of III-V nanowires.",
        "positive": "Structural and magnetic properties of S = 3/2 chemically disordered\n  perovskite Sr2TiMnO6: Single phase polycrystalline sample of perovskite Sr2TiMnO6 (STMO) has been\nsuccessfully synthesized via solid state reaction route. Its detailed\nstructural and physical properties have been studied using x-ray diffraction,\ntransmission electron microscopy, magnetization, specific heat, and dielectric\nmeasurements. Rietveld analysis of the powder XRD data and transmission\nelectron microscopy studies confirm that STMO is not a double perovskite\nstructure with Fm-3m space group. But it is a disordered perovskite structure\nwith Pm-3m space group where Ti4+ and Mn4+ ions are randomly distributed at the\n1b site. The dc magnetization (\\c{hi}dc-vs-T) measurements in the temperature\nrange 2-300K reveals a single anomaly at ~13K with predominant long range\ncanted antiferromagnetic (AFM) ordering. The frequency invariant maxima at 13K\nin the ac susceptibility (\\c{hi}ac-vs-T) discards the spin-glass behaviour in\nSTMO. Despite the presence of sharp feature in M-T data, the specific heat data\n(Cp-vs-T) shows only a broad hump around 13K, which has been attributed to the\nmagneto-structural ordering giving rise to canted AFM state in chemically\ndisorder STMO. Matching with the magnetic and specific heat anomaly, the\ndielectric permittivity also shows a broad anomaly around 14K, indicating the\npossible magneto-dielectric coupling in STMO."
    },
    {
        "anchor": "Surface Resistance Imaging with a Scanning Near-Field Microwave\n  Microscope: We describe near-field imaging of sample sheet resistance via frequency\nshifts in a resonant coaxial scanning microwave microscope. The frequency\nshifts are related to local sample properties, such as surface resistance and\ndielectric constant. We use a feedback circuit to track a given resonant\nfrequency, allowing measurements with a sensitivity to frequency shifts as\nsmall as one parts in 50000 for a 30 ms sampling time. The frequency shifts can\nbe converted to sheet resistance based on a simple model of the system.",
        "positive": "Design monolayer iodinenes based on halogen bond and tiling theory: Xenes, two-dimensional (2D) monolayers composed of a single element, with\ngraphene as a typical representative, have attracted widespread attention. Most\nof the previous Xenes, X from group-IIIA to group-VIA elements have bonding\ncharacteristics of covalent bonds. In this work, we for the first time unveil\nthe pivotal role of a halogen bond, which is a distinctive type of bonding with\ninteraction strength between that of a covalent bond and a van der Waals\ninteraction, in 2D group-VIIA monolayers. Combing the ingenious\nnon-edge-to-edge tiling theory and state-of-art ab initio method with refined\nlocal density functional M06-L, we provide a precise and effective bottom-up\nconstruction of 2D iodine monolayer sheets, iodinenes, primarily governed by\nhalogen bonds, and successfully design a category of stable iodinenes,\nencompassing herringbone, Pythagorean, gyrated truncated hexagonal, i.e.\ndiatomic-kagome, and gyrated hexagonal tiling pattern. These iodinene\nstructures exhibit a wealth of properties, such as flat bands, nontrivial\ntopology, and fascinating optical characteristics, offering valuable insights\nand guidance for future experimental investigations. Our work not only unveils\nthe unexplored halogen bonding mechanism in 2D materials but also opens a new\navenue for designing other non-covalent bonding 2D materials."
    },
    {
        "anchor": "First-principles Simulations of a Graphene Based Field-Effect Transistor: We improvise a novel approach to carry out first-principles simulations of\ngraphene-based vertical field effect tunneling transistors that consist of a\ngraphene$|${\\it h}-BN$|$graphene multilayer structure. Within the density\nfunctional theory framework, we exploit the effective screening medium (ESM)\nmethod to properly treat boundary conditions for electrostatic potentials and\ninvestigate the effect of gate voltage. The distribution of free carriers and\nthe band structure of both top and bottom graphene layers are calculated\nself-consistently. The dielectric properties of {\\it h}-BN thin films\nsandwiched between graphene layers are computed layer-by-layer following the\ntheory of microscopic permittivity. We find that the permittivities of BN\nlayers are very close to that of crystalline {\\it h}-BN. The effect of\ninterface with graphene on the dielectric properties of {\\it h}-BN is weak,\naccording to an analysis on the interface charge redistribution.",
        "positive": "Range separated functionals in the density functional based tight\n  binding method: Formalism: A generalization of the density-functional based tight-binding method (DFTB)\nfor the use with range-separated exchange-correlation functionals is presented.\nIt is based on the Generalized Kohn-Sham (GKS) formalism and employs the\ndensity matrix as basic variable in the expansion of the energy functional, in\ncontrast to the traditional DFTB scheme. The GKS-TB equations are derived and\nappropriate integral approximations are discussed in detail. Implementation\nissues and numerical aspects of the new scheme are also covered."
    },
    {
        "anchor": "Photogalvanic Effect in Silicene: Silicene has introduced itself as an outstanding novel material, which seeks\nits meritorious place among common spintronic devices like Cu and Ag. In this\nwork, photogalvanic effect in silicene is studied within the semi-classical\napproach and beyond Dirac point approximation. Normal electric field plays the\nrole of effective pseudo-magnetic field which breaks the inversion symmetry and\nsplits the conduction and valence bands. The interplay between this external\nfield and intrinsic spin-orbit coupling provides spin-valley locking in\nsilicene. Spin-valley locking in silicene makes this material superior to its\ncarbon counterpart, graphene. Since the absorption of the polarized photons is\nnot equivalent at both of the valleys, spin-valley locking leads to a\nspin-polarized photocurrent injection.",
        "positive": "Efficient determination of alloy ground-state structures: We propose an efficient approach to accurately finding the ground-state\nstructures in alloys based on the cluster expansion method. In this approach, a\nsmall number of candidate ground-state structures are obtained without any\ninformation of the energy. To generate the candidates, we employ the convex\nhull constructed from the correlation functions of all possible structures by\nusing an efficient algorithm. This approach is applicable to not only simple\nlattices but also complex lattices. Firstly, we evaluate the convex hulls for\nbinary alloys with four types of simple lattice. Then we discuss the structures\non the vertices. To examine the accuracy of this approach, we perform a set of\ndensity functional theory calculations and the cluster expansion for Ag-Au\nalloy and compare the formation energies of the vertex structures with those of\nall possible structures. As applications, the ground-state structures of the\nintermetallic compounds CuAu, CuAg, CuPd, AuAg, AuPd, AgPd, MoTa, MoW and TaW\nare similarly evaluated. Finally, the energy distribution is obtained for\ndifferent cation arrangements in MgAl$_2$O$_4$ spinel, for which long-range\ninteractions are essential for the accurate description of its energetics."
    },
    {
        "anchor": "Novel multiferroics with ferromagnetic phase induced in paraelectric\n  antiferromagnets by electric field application: The phase diagram of a quantum paraelectric antiferromagnet EuTiO3 under an\nexternal electric field was calculated using Landau-Ginzburg-Devonshire theory.\nIt was shown that the application of an external electric field E leads to the\nappearance of a ferromagnetic phase due to the magnetoelectric coupling. In\nparticular, electric field application decreases the transition temperature\nTAFM to antiferromagnetic (AFM) phase and induces ferromagnetic (FM) phase, so\nthat at some E field larger than the critical field (Ecr), TFM becomes higher\nthan TAFM and the FM phase appears. Note that Ecr increases and magnetization\ndecreases as the temperature increases. The value of the critical field Ecr =\n0.40*10^6 V/cm we calculated appeared close to the value Ecr = 0.5*10^6 V/cm\nobtained recently by Ryan et al. with the help of density functional theory for\nEuTiO3 film under a compressive strain produced by substrate. At the fields E\n>0.83*10^6 V/cm, AFM disappears for all considered temperatures and so FM\nbecomes the only stable magnetic phase. We find that ferromagnetic phase can be\ninduced by an E-field in other paraelectric antiferromagnet oxides with a\npositive AFM-type magnetoelectric (ME) coupling coefficient and negative\nFM-type ME coupling coefficient. In particular, the critical E-field was\nestimated for another paraelectric antiferromagnet Sr0.7Ba0.3MnO3 as\n0.2x10^5V/cm at 0 K. Analysis of the dependence of magnetization and\nantimagnetization on the external electric field and the polarization induced\nby the field, which yields the magnetoelectric coupling, is reported. The\nresults show the possibility to control multiferroicity, including the FM and\nAFM phases, with help of an electric field application.",
        "positive": "Topologically close-packed phases in binary transition-metal compounds:\n  matching high-throughput ab initio calculations to an empirical structure map: In steels and single-crystal superalloys the control of the formation of\ntopologically close-packed (TCP) phases is critical for the performance of the\nmaterial. The structural stability of TCP phases in multi-component\ntransition-metal alloys may be rationalised in terms of the average\nvalence-electron count $\\bar{N}$ and the composition-dependent relative\nvolume-difference $\\overline{\\Delta V/V}$. We elucidate the interplay of these\nfactors by comparing density-functional theory calculations to an empirical\nstructure map based on experimental data. In particular, we calculate the heat\nof formation for the TCP phases A15, C14, C15, C36, $\\chi$, $\\mu$, and $\\sigma$\nfor all possible binary occupations of the Wyckoff positions. We discuss the\nisovalent systems V/Nb-Ta to highlight the role of atomic-size difference and\nobserve the expected stabilisation of C14/C15/C36/$\\mu$ by $\\overline{\\Delta\nV/V}$ at $\\Delta N=0$ in V-Ta. In the systems V/Nb-Re, we focus on the\nwell-known trend of A15$- \\sigma - \\chi$ stability with increasing $\\bar{N}$\nand show that the influence of $\\overline{\\Delta V/V}$ is too weak to stabilise\nC14/C15/C36/$\\mu$ in Nb-Re. As an example for a significant influence of both\n$\\bar{N}$ and $\\overline{\\Delta V/V}$, we also consider the systems Cr/Mo-Co.\nHere the sequence A15$- \\sigma - \\chi$ is observed in both systems but in Mo-Co\nthe large size-mismatch stabilises C14/C15/C36/$\\mu$. We also include V/Nb-Co\nthat cover the entire valence range of TCP stability and also show the\nstabilisation of C14/C15/C36/$\\mu$. Moreover, the combination of a large volume\ndifference with a large mismatch in valence-electron count reduces the\nstability of the A15/$\\sigma$/$\\chi$ phases in Nb-Co as compared to V-Co. By\ncomparison to non-magnetic calculations we also find that magnetism is of minor\nimportance for the structural stability of TCP phases in Cr/Mo-Co and in\nV/Nb-Co."
    },
    {
        "anchor": "Topological phases and nonreciprocal edge states in non-Hermitian\n  Floquet Insulators: Topological phases in quantum and classical systems have been of significant\nrecent interest due to their fascinating physical properties. While a range of\ndifferent mechanisms to induce topological order have been introduced, a quest\nfor the most viable solution for practical systems is still open. Floquet\ntopological insulator represent one of possible venues to engineer topological\nphases, yet they have been so far largely restricted to temporal modulation of\nHermitian potentials. On the other hand, in many physical systems, including\nacoustic and optical systems, modulating loss or gain can be more\nstraightforwardly achieved. Two of such examples are graphene, which enables\nstrong modulation of its conductivity due to saturable absorption, and quantum\nwells where population inversion can be achieved in an ultrafast manner. On the\nother hand, non-Hermitian Floquet potentials have not been shown to yield novel\ntopological phases to date. It is therefore of great interest to explore\ntime-modulated non-Hermitian potentials in periodic lattices, and the emergence\nof topological phases associated with them. Here we demonstrate that\nnon-Hermitian Hamiltonians can indeed result in topological phases supporting\nnonreciprocal edge states propagating without dissipation, as well as new\nregimes of dissipative and amplifying topological edge transport.",
        "positive": "Range optimized theory of electron liquids with application to the\n  homogeneous gas: A simple optimization scheme is used to compute the density-density response\nfunction of an electron liquid. Higher order terms in the perturbation\nexpansion beyond the random phase approximation are summed approximately by\nenforcing the constraint that the spin density pair correlation functions be\npositive. The theory is applied to the 3-D homogeneous electron gas at zero\ntemperature. Quantitative comparison is made with previous theory and data from\nquantum Monte Carlo simulation. When thermodynamic consistency is enforced on\nthe compressibility, agreement with the available simulation data is very good\nfor the entire paramagnetic region, from weakly to strongly correlated\ndensities. In this case, the accuracy of the theory is comparable to or better\nthan the best of previous theory, including the full GW approximation. In\naddition, it is found that the spin susceptibility diverges at a lower density\n($r_s \\approx 107$) than the current estimate for the liquid-solid transition.\nApplication of the theory to inhomogeneous electron liquids is discussed."
    },
    {
        "anchor": "Penetration of alkali atoms throughout graphene membrane: theoretical\n  modeling: Theoretical studies of penetration of various alkali atoms (Li, Na, Rb, Cs)\nthroughout graphene membrane grown on silicon carbide substrate are reported\nand compared with recent experimental results. Results of first principles\nmodeling demonstrate rather low (about 0.8 eV) energy barrier for the formation\nof temporary defects in carbon layer required for the penetration of Li at high\nconcentration of adatoms, higher (about 2 eV) barrier for Na, and barriers\nabove 4 eV for Rb and Cs. Experiments prove migration of lithium adatoms from\ngraphene surface to the buffer layer and SiC substrate at room temperature,\nsodium at 100{\\deg}C and impenetrability of graphene membrane for Rb and Cs.\nDifferences between epitaxial and free standing graphene for the penetration of\nalkali ions are also discussed.",
        "positive": "From wurtzite nanoplatelets to zinc blende nanorods: Simultaneous\n  control of shape and phase in ultrathin ZnS nanocrystals: Ultrathin semiconductor nanocrystals (NCs) with at least one dimension below\ntheir exciton Bohr radius receive a rapidly increasing attention due to their\nunique physicochemical properties such as strong quantum confinement, large\nsurface-to-volume ratio, and giant oscillator strength. These superior\nproperties highly depend on the shape and crystal phase of semiconductor NCs.\nSlight changes in the shape and phase of NCs can cause significant changes in\ntheir properties. Therefore, it is crucial to controllably synthesize\nsemiconductor NCs. Here, we demonstrate not only the synthesis of robust\nwell-defined ultrathin ZnS nanoplatelets (NPLs) with excitonic absorption and\nemission, but also the precise shape and phase control of ZnS NCs based on a\nsoft template strategy. The key feature of our approach is the tuning of the\nsulfur precursor amount, resulting in a simultaneous shape/phase transformation\nbetween wurtzite (WZ) ZnS NPLs and zinc blende (ZB) ZnS nanorods (NRs) at\nmoderate temperatures (150 degree). UV-vis absorption and photoluminescence\n(PL) spectra reveal very distinct optical properties between WZ-ZnS NPLs and\nZB-ZnS NRs. UV-vis absorption spectra of WZ-ZnS NPLs clearly exhibit a sharp\nexcitonic peak that is not observed in ZB-ZnS NRs. Besides, the PL\ncharacterization shows that WZ-ZnS NPLs have a narrow excitonic emission peak\n(292 nm), while the ZB-ZnS NRs exhibit a broad collective emission band\nconsisting of four emission peaks (335, 359, 395, and 468 nm). The appearance\nof excitonic features in the absorption spectra of ZnS NPLs is explained by\ninterband electronic transitions, which is simulated in the framework of\ndensity functional theory (DFT). The presented simple and effective synthetic\nstrategy opens a new path to synthesize further NCs with shape and phase\ncontrol for advanced applications in electronics and photonics."
    },
    {
        "anchor": "Electronic properties of edge-functionalized zigzag graphene nanoribbons\n  on SiO2 substrate: Based on first-principles calculations, electronic properties of\nedge-functionalized zigzag graphene nanoribbons (ZGNRs) on SiO2 substrate are\npresented. Metallic or semiconducting properties of ZGNRs are revealed due to\nvarious interactions between edge-hydrogenated ZGNRs and different SiO2 (0001)\nsurfaces. Bivalent functional groups decorating ZGNRs serve as the bridge\nbetween active edges of ZGNRs and SiO2. These functional groups stabilize ZGNRs\non substrate, as well as modify the edge states of ZGNRs and further affect\ntheir electronic properties. Band gaps are opened owing to edge states\ndestruction and distorted lattice in ZGNRs.",
        "positive": "A first-principles approach to closing the \"10-100 eV gap\" for\n  charge-carrier thermalization in semiconductors: The present work is concerned with studying accurately the energy-loss\nprocesses that control the thermalization of hot electrons and holes that are\ngenerated by high-energy radiation in wurtzite GaN, using an ab initio\napproach. Current physical models of the nuclear/particle physics community\ncover thermalization in the high-energy range (kinetic energies exceeding ~100\neV), and the electronic-device community has studied extensively carrier\ntransport in the low-energy range (below ~10 eV). However, the processes that\ncontrol the energy losses and thermalization of electrons and holes in the\nintermediate energy range of about 10-100 eV (the \"10-100 eV gap\") are poorly\nknown. The aim of this research is to close this gap, by utilizing density\nfunctional theory (DFT) to obtain the band structure and dielectric function of\nGaN for energies up to about 100 eV. We also calculate charge-carrier\nscattering rates for the major charge-carrier interactions (phonon scattering,\nimpact ionization, and plasmon emission), using the DFT results and first-order\nperturbation theory. With this information, we study the thermalization of\nelectrons starting at 100 eV using the Monte Carlo method to solve the\nsemiclassical Boltzmann transport equation. Full thermalization of electrons\nand holes is complete within ~1 and 0.5 ps, respectively. Hot electrons\ndissipate about 90% of their initial kinetic energy to the electron-hole gas\n(90 eV) during the first ~0.1 fs, due to rapid plasmon emission and impact\nionization at high energies. The remaining energy is lost more slowly as phonon\nemission dominates at lower energies (below ~10 eV). During the thermalization,\nhot electrons generate pairs with an average energy of ~8.9 eV/pair (11-12\npairs per hot electron). Additionally, during the thermalization, the maximum\nelectron displacement from its original position is found to be on the order of\n100 nm."
    },
    {
        "anchor": "First principles prediction of the Al-Li phase diagram including\n  configurational and vibrational entropic contributions: The whole Al-Li phase diagram is predicted from first principles calculations\nand statistical mechanics including the effect of configurational and\nvibrational entropy. The formation enthalpy of different configurations at\ndifferent temperatures was accurately predicted by means of cluster expansions\nthat were fitted from first principles calculations. The vibrational entropic\ncontribution of each configuration was determined from the bond length vs. bond\nstiffness relationships for each type of bond and the Gibbs free energy of the\ndifferent phases was obtained as a function of temperature from Monte Carlo\nsimulations. The predicted phase diagram was in excellent agreement with the\ncurrently accepted experimental one in terms of the stable (AlLi, Al2Li3,\nAlLi2, Al4Li9) and metastable (Al3Li) phases, of the phase boundaries between\nthem and of the maximum stability temperature of line compounds. In addition,\nit provided accurate information about the gap between Al3Li and AlLi solvus\nlines. Finally, the influence of the vibrational entropy on the correct\nprediction of the phase diagram is discussed. Overall, the methodology shows\nthat accurate phase diagrams of alloys of technological interest can be\npredicted from first principles calculations.",
        "positive": "Glide Symmetry Protected Higher-Order Topological Insulators from\n  Semimetals with butterfly-like Nodal Lines: Most topological insulators discovered today in spinful systems can be\ntransformed from topological semimetals (TSMs) with vanishing bulk gap via\nintroducing the spin-orbit coupling (SOC), which manifests the intrinsic links\nbetween the gapped TI phases and the gapless TSMs. Recently, we have proposed a\nnew family of TSMs in time-reversal invariant {\\it spinless} systems, which\nhost butterfly-like nodal-lines (NLs) consisting of a pair of identical\nconcentric intersecting coplanar ellipses (CICE). In this Communication, we\nunveil the intrinsic link between this exotic class of nodal-line semimetals\n(NLSMs) and a $\\mathbb{Z}_{4}$ = 2 topological crystalline insulator (TCI), by\nincluding substantial SOC. We demonstrate that in three space groups ({\\it\ni.e.} $Pbam$ (No.55), $P4/mbm$ (No.127) and $P4_2/mbc$ (No.135)), the TCI\nsupports a fourfold Dirac fermion on the (001) surface protected by two glide\nsymmetries, which originates from the intertwined drumhead surface states of\nthe CICE NLs. The higher order topology is further demonstrated by the\nemergence of one-dimensional helical hinge states, indicating a new higher\norder topological insulator protected by a glide symmetry."
    },
    {
        "anchor": "Mechanical Energy Absorption of Architecturally Interlocked\n  Petal-Schwarzites: We carried out fully atomistic reactive molecular dynamics simulations to\nstudy the mechanical behavior of six newly proposed hybrid schwarzite-based\nstructures (interlocked petal-schwarzites). Schwarzites are carbon crystalline\nnanostructures with negative Gaussian curvature created by mapping a TPMS\n(Triply Periodic Minimal Surface) with carbon rings containing six to eight\natoms. Our simulations have shown that petal-schwarzite structures can\nwithstand uni-axial compressive stress up to the order of GPa and can be\ncompressed past 50 percent strain without structural collapse. Our most\nresistant hierarchical structure has a calculated compressive strength of\n260~GPa and specific energy absorption (SEA) of 45.95 MJ/kg, while possessing a\nmass density of only 685 kg/m$^3$. These results show that these structures\ncould be excellent lightweight materials for applications that require\nmechanical energy absorption.",
        "positive": "Large Spin Pumping from Epitaxial Y3Fe5O12 Thin Films to Pt and W Layers: Epitaxial Y3Fe5O12 thin films have been deposited by off-axis sputtering,\nwhich exhibit excellent crystalline quality, enabling observation of large spin\npumping signals in Pt/Y3Fe5O12 and W/Y3Fe5O12 bilayers driven by cavity\nferromagnetic resonance. The inverse spin Hall voltages reach 2.10 mV and -5.26\nmV in 5-mm long Pt/Y3Fe5O12 and W/Y3Fe5O12 bilayers, respectively, excited by a\nradio-frequency magnetic field of 0.3 Oe. From the ferromagnetic resonance\nlinewidth broadening, the interfacial spin mixing conductance of 4.56E14\n{\\Omega}-1m-2 and 2.30E14 {\\Omega}-1m-2 are obtained for Pt/Y3Fe5O12 and\nW/Y3Fe5O12 bilayers, respectively."
    },
    {
        "anchor": "Tungsten material properties at high temperature and high stress: Recently reported results on the long lifetime of the tungsten samples under\nhigh temperature and high stress conditions expected in the Neutrino Factory\ntarget have strengthened the case for a solid target option for the Neutrino\nFactory. In order to study in more details the behaviour of basic material\nproperties of tungsten, a new method has been developed for measurement of\ntungsten Young's modulus at high stress, high strain-rates (> 1000 s^-1) and\nvery high temperatures (up to 2650 C). The method is based on measurements of\nthe surface motion of tungsten wires, stressed by a pulsed current, using a\nLaser Doppler Vibrometer. The measured characteristic frequencies of wire\nexpansion and contraction under the thermal loading have been used to directly\nobtain the tungsten Young's modulus as a function of applied stress and\ntemperature. The experimental results have been compared with modelling results\nand we have found that they agree very well. From the point of view of future\nuse of tungsten as a high power target material, the most important result of\nthis study is that Young's modulus of tungsten remains high at high\ntemperature, high stress and high strain-rates.",
        "positive": "Novel Two-Dimensional Layered MSi$_2$N$_4$ (M = Mo, W): New Promising\n  Thermal Management Materials: With the miniaturization and integration of nanoelectronic devices, efficient\nheat removal becomes a key factor affecting the reliable operation of the\nnanoelectronic device. With the high intrinsic thermal conductivity, good\nmechanical flexibility, and precisely controlled growth, two-dimensional (2D)\nmaterials are widely accepted as ideal candidates for thermal management\nmaterials. In this work, by solving the phonon Boltzmann transport equation\n(BTE) based on first-principles calculations, we comprehensively investigated\nthe thermal conductivity of novel 2D layered MSi$_2$N$_4$ (M = Mo, W). Our\nresults point to competitive thermal conductivities (162 W/mK) of monolayer\nMoSi$_2$N$_4$, which is around two times larger than that of WSi$_2$N$_4$ and\nseven times larger than that of silicene despite their similar non-planar\nstructures. It is revealed that the high thermal conductivity arises mainly\nfrom its large group velocity and low anharmonicity. Our result suggests that\nMoSi$_2$N$_4$ could be a potential candidate for 2D thermal management\nmaterials."
    },
    {
        "anchor": "Multiscale characterization of interfacial region in flexible rubber\n  composites: initial structure and evolution upon thermal treatment: To investigate the structural changes upon thermal treatment of resorcinol\nformaldehyde latex (RFL) interfacial layer in rubber-cord flexible composite, a\nmultiscale approach has been employed. High-resolution AFM mapping showed a\nsignificant increase of the modulus of the RF phase from 1.2 GPa to 2.3 GPa and\nlatex phase (L) from 0.3 GPa to 0.8 GPa after a thermal exposure at 100{\\deg}C\nfor 10 days. The increase of the RF and L phases elastic modulus was correlated\nwith the increase of the oxygen content in RFL layer based on the measurements\nby SEM-EDX. Besides by combining finite element simulations and AFM modulus\nprofiling, the presence of an interphase region (over 280 nm) between the RFL\nand the rubber regions was identified and was not deteriorated by the thermal\ntreatment. Peel adhesion testing revealed that the increase of RF and L phases\nrigidity after thermal treatment was detrimental for the interfacial adhesion\nof the rubber composite.",
        "positive": "Influence of s,p-d and s-p exchange couplings on exciton splitting in\n  (Zn,Mn)O: This work presents results of near-band gap magnetooptical studies on\n(Zn,Mn)O epitaxial layers. We observe excitonic transitions in reflectivity and\nphotoluminescence, that shift towards higher energies when the Mn concentration\nincreases and split nonlinearly under the magnetic field. Excitonic shifts are\ndetermined by the s,p-d exchange coupling to magnetic ions, by the\nelectron-hole s-p exchange, and the spin-orbit interactions. A quantitative\ndescription of the magnetoreflectivity findings indicates that the free\nexcitons A and B are associated with the Gamma_7 and Gamma_9 valence bands,\nrespectively, the order reversed as compared to wurtzite GaN. Furthermore, our\nresults show that the magnitude of the giant exciton splittings, specific to\ndilute magnetic semiconductors, is unusual: the magnetoreflectivity data is\ndescribed by an effective exchange energy N_0(beta-alpha)=+0.2+/-0.1 eV, what\npoints to small and positive N_0 beta. It is shown that both the increase of\nthe gap with x and the small positive value of the exchange energy N_0 beta\ncorroborate recent theory describing the exchange splitting of the valence band\nin a non-perturbative way, suitable for the case of a strong p-d hybridization."
    },
    {
        "anchor": "Neutron Diffraction Studies on Chemical and Magnetic Structure of\n  Multiferroic PbFe0.67W0.33O3: We report on the single phase synthesis and room temperature structural\ncharacterization of PbFe0.67W0.33O3 (PFW) multiferroic. The PFW was synthesized\nby low temperature sintering, Columbite method. Analysis of powder XRD pattern\nexhibits single phase formation of PFW with no traces of pyrochlore phase.\nDetailed analysis of room temperature neutron diffraction (ND) reveals cubic\nphase at room temperature, space group Pm-3m. The ND pattern clearly reveals\nmagnetic Bragg peak at 2theeta = 18.51 (Q = 1.36{\\AA}-1). The refinement of\nmagnetic structure reveals G-type antiferromagnetic structure in PFW at room\ntemperature. The dielectric constant and loss tangent decreases with increasing\nfrequency. The room temperature P-E measurements shows a non-linear slim\nhysteresis, typical nature of relaxor multiferroics, with saturation and\nremnant polarizations of Ps = 1.50 microC/cm2 and Pr = 0.40 microC/cm2,\nrespectively.",
        "positive": "OH terminated two-dimensional transition metal carbides and nitrides\n  (MXenes) as ultralow work function materials: MXenes are a set of two-dimensional transition metal carbides and nitrides\nthat offer many potential applications in energy storage and electronic\ndevices. As an important parameter to design new electronic devices, we\ninvestigate the work functions of bare MXenes and their functionalized ones\nwith F, OH, and O chemical groups using first-principles calculations. From our\ncalculations, it turns out that the OH terminated MXenes attain ultralow work\nfunctions between 1.6 and 2.8 eV. Moreover, depending on the type of the\ntransition metal, the F or O functionalization affects increasing or decreasing\nthe work functions. We show that the changes in the work functions upon\nfunctionalizations are linearly correlated with the changes in the surface\ndipole moments. It is shown that the work functions of the F or O terminated\nMXenes are controlled by two factors: the induced dipole moments by the charge\ntransfers between F/O and the substrate, and the changes in the total surface\ndipole moments caused by surface relaxation upon the functionalization.\nHowever, in the cases of the OH terminated MXenes, in addition to these two\nfactors, the intrinsic dipole moments of the OH groups play an important role\nin determining the total dipole moments and consequently justify their ultralow\nwork functions."
    },
    {
        "anchor": "Optical properties of (In,Ga)As capped InAs quantum dots grown on [11k]\n  substrates: Using three-dimensional k.p calculation including strain and\npiezoelectricity, we showed that the size of the quantum dot (QD) in the growth\ndirection determines the influence of the (In,Ga)As capping layer on the\noptical properties of [11k] grown InAs QDs, where k=1,2,3. For flat dots,\nincrease of In concentration in the capping layer leads to a decrease of the\ntransition energy, as is the case of [001] grown QDs, whereas for large dots an\nincrease of the In concentration in the capping layer is followed by an\nincrease of the transition energy up to a critical concentration of In, after\nwhich the optical transition energy starts to decrease.",
        "positive": "Role of strain on the stability of B, C, N, and O in Iron: The preference for the occupation of solute atoms like B, C, N, and O at\nvarious sites in iron is generally explained by the size of the solute and the\nvolume available for the solute atoms to occupy. Such an explanation based on\nthe size of solute atoms and available space at the occupation site assumes\nthat distortion alone dictates the stability of solute atoms. Using\nfirst-principles density functional theory (DFT), we separately calculate the\ndistortion energy (DE) and electronic binding energy (EBE) of solute atoms in\niron. We show that electronic binding dictates the relative stability of O\nrather than distortion. In contrast, the relative stability of B, C, and N is\ndictated by the distortion it exerts on iron atoms. Contribution to the\nrelative stability of B atoms is dictated mostly by distortion. It suggests\nthat B could occupy a large volume region like grain boundaries. The same\nagrees with experiments indicating B segregates at grain boundaries and planar\ndefects. Such conclusions could not have been drawn from the formation energy\ncalculation, which shows that B is stable at the substitution site."
    },
    {
        "anchor": "Layer-number-dependent spin Hall effects in transition metal\n  monocarbides $M_{2}\\rm{C}$ ($M=\\rm{V}, \\rm{Nb}, \\rm{Ta}$): The recent discovery of strong spin Hall effects (SHE) in 2D layered\ntopological semimetals has attracted intensive attention due to its exotic\nelectronic properties and potential applications in spintronic devices. In this\npaper, we systematically study the topological properties and intrinsic SHE of\nlayered transition metal carbides $M_{2}\\rm{C}$ ($M=\\rm{V}, \\rm{Nb}, \\rm{Ta}$).\nThe results show that both bulk and monolayer $M_{2}\\rm{C}$ have\nsymmetry-protected nodal points (NPs) and lines (NLs) originating from the $d$\nband crossing near the Fermi level ($E_F$). The inclusion of SOC breaks the\ndegeneracy of NLs and NPs, contributing to large spin Hall conductivity (SHC)\nup to $\\sim$1100 and $\\sim$200 $(\\hbar / e)(\\Omega \\mathrm{cm})^{-1}$ for bulk\nand monolayer Ta$_{2}$C, respectively. Remarkably, we find that magnitude of\nSHC exhibits a significant enhancement by increasing the layer number. For\neight-layer Ta$_{2}$C, the maximum value of SHC can reach up to $\\sim$600\n$(\\hbar / e)(\\Omega \\mathrm{cm})^{-1}$, comparable to many reported 3D\ntopological materials. Analysis of spin Berry curvature reveals that the large\nSHC originates from layer-number-dependent nodal line structure near the $E_F$,\nin which the repeated crossover between valence and conduction bands creates\nlarge amounts of NPs along the $\\Gamma\\rm{-K}$ route. Our findings not only\nprovide a new platform for experimental research of low-dimensional SHE, but\nalso suggest an effective way of realizing giant SHE by controlling layer\nthickness.",
        "positive": "Zero valley splitting at zero magnetic field for strained Si/SiGe\n  quantum wells grown on tilted substrates: The electronic structure for a strained Si/SiGe quantum well grown on a\ntilted substrate with periodic steps is calculated using a parameterized\ntight-binding method. For a zero tilt angle the energy difference between the\ntwo lowest minima of the conduction band at the center of the Brillouin zone\ndefines a non-zero valley splitting. At finite tilt angles, the two lowest\nconduction band minima shift to k0 and -k0 in the Brillouin zone and have equal\nenergy. The valley splitting for quantum wells grown on a tilted substrate is\ntherefore equal to zero, which is a direct consequence of the periodicity of\nthe steps at the interfaces between the quantum well and the buffer materials."
    },
    {
        "anchor": "Carbon Decorated TiO2 Nanotube Membranes: A Renewable Nanofilter for\n  Size- and Charge Selective Enrichment of Proteins: In this work, we design a TiO2 nanomembrane (TiNM) that can be used as a\nnanofilter platform for a selective enrichment of specific proteins. After use\nthe photocatalytic properties of TiO2 allow to decompose unwanted remnant on\nthe substrate and thus make the platform reusable. To construct this platform\nwe fabricate a free-standing TiO2 nanotube array and remove the bottom oxide to\nform a both-end open TiNM. By pyrolysis of the natural tube wall contamination\n(C/TiNM), the walls become decorated with graphitic carbon patches. Owing to\nthe large surface area, the amphiphilic nature and the charge adjustable\ncharacter, this C/TiNM can be used to extract and enrich hydrophobic and\ncharged biomolecules from solutions. Using human serum albumin (HSA) as a model\nprotein as well as protein mixtures, we show that the composite membrane\nexhibits a highly enhanced loading capacity and protein selectivity and is\nreusable after a short UV treatment.",
        "positive": "High-entropy high-hardness metal carbides discovered by entropy\n  descriptors: High-entropy materials have attracted considerable interest due to the\ncombination of useful properties and promising applications. Predicting their\nformation remains the major hindrance to the discovery of new systems. Here we\npropose a descriptor - entropy forming ability - for addressing\nsynthesizability from first principles. The formalism, based on the energy\ndistribution spectrum of randomized calculations, captures the accessibility of\nequally-sampled states near the ground state and quantifies configurational\ndisorder capable of stabilizing high-entropy homogeneous phases. The\nmethodology is applied to disordered refractory 5-metal carbides - promising\ncandidates for high-hardness applications. The descriptor correctly predicts\nthe ease with which compositions can be experimentally synthesized as rock-salt\nhigh-entropy homogeneous phases, validating the ansatz, and in some cases,\ngoing beyond intuition. Several of these materials exhibit hardness up to 50%\nhigher than rule of mixtures estimations. The entropy descriptor method has the\npotential to accelerate the search for high-entropy systems by rationally\ncombining first principles with experimental synthesis and characterization."
    },
    {
        "anchor": "Fermi surfaces of single layer dielectrics on transition metals: Single sheets of hexagonal boron nitride on transition metals provide a model\nsystem for single layer dielectrics. The progress in the understanding of h-BN\nlayers on transition metals of the last 10 years are shortly reviewed.\nParticular emphasis lies on the boron nitride nanomesh on Rh(111), which is a\ncorrugated single sheet of h-BN, where the corrugation imposes strong lateral\nelectric fields. Fermi surface maps of h-BN/Rh(111) and Rh(111) are compared. A\nh-BN layer on Rh(111) introduces no new bands at the Fermi energy, which is\nexpected for an insulator. The lateral electric fields of h-BN nanomesh violate\nthe conservation law for parallel momentum in photoemission and smear out the\nmomentum distribution curves on the Fermi surface.",
        "positive": "Unravelling densification during sintering by multiscale modelling of\n  grain motion: The resulting microstructure after the sintering process determines many\nmaterials properties of interest. In order to understand the microstructural\nevolution, simulations are often employed. One such simulation method is the\nphase-field method, which has garnered much interest in recent decades.\nHowever, the method lacks a complete model for sintering, as previous works\ncould show unphysical effects and the inability to reach representative volume\nelements. Thus the present paper aims to close this gap by employing molecular\ndynamics and determining rules of motion which can be translated to a\nphase-field model. The key realization is that vacancy absorption induced\nmotion of grains travels through a grain structure without resistance. Hence\nthe total displacement field of a green body is simply the superposition of all\ngrains reacting in isolation to local vacancy absorption events. The resulting\nphase-field model is shown to be representative starting from particle counts\nbetween 97 and 262 and contains the qualitative correct dependence of sintering\nrate on particle size."
    },
    {
        "anchor": "The role of screened exact exchange in accurately describing properties\n  of transition metal oxides: Modeling defects in LaAlO3: The properties of many intrinsic defects in the wide band gap semiconductor\nLaAlO3 are studied using the screened hybrid functional of Heyd, Scuseria, and\nErnzerhof (HSE). As in pristine structures, exact exchange included in the\nscreened hybrid functional alleviates the band gap underestimation problem,\nwhich is common to semilocal functionals; this allows accurate prediction of\ndefect properties. We propose correction-free defect energy levels for bulk\nLaAlO3 computed using HSE that might serve as guide in the interpretation of\nphotoluminescence experiments.",
        "positive": "Strain engineering of topological magnons in chromium trihalides from\n  first-principles: Recent experiments evidence the direct observation of spin waves in chromium\ntrihalides and a gap at the Dirac points of the magnon dispersion in bulk\nCrI$_3$. However, the topological origin of this feature remains unclear and\nits emergence at the 2D limit has not yet been proven experimentally. Herein,\nwe perform a fully self-consistent ab initio analysis that supports the\npresence of topological magnons in chromium trihalides monolayers. Our results\nconfirm the existence of a gap around the K high-symmetry point in the linear\nmagnon dispersion of CrI$_3$, which originates as a direct consequence of\nintralayer Dzyaloshinskii-Moriya (DM) interaction. In addition, our orbital\nresolved analysis reveals the microscopic mechanisms that can be exploited\nusing strain engineering to increase the strength of the DM interaction and\nthus control the gap size in CrI$_3$. This paves the way to the further\ndevelopment of this family of materials as building-blocks for topological\nmagnonics at the limit of miniaturization."
    },
    {
        "anchor": "Dimensionless Mapping: A Combinatorial Algorithm to Design Invisible\n  Dopants: Electronic cloaking has been recently suggested to design invisible dopants\nwith electronic scattering cross sections smaller than 1% of the physical cross\nsection ( . Cloaking layers could be designed to coat nanoparticle dopants to\nminimally scatter conduction electrons and to enhance the electronic mobility.\nIn some cases, such enhancements would result in larger thermoelectric power\nfactors. The main difficulty is the fact that the created potential upon\ncoating is not tunable and is determined by the band alignment of the chosen\nmaterials for the core, the shell and the host as well as the charge\ndistribution in these layers. To find proper combinations of materials, one\nneeds to probe a large class of materials combinations and layer sizes. This\napproach is time-consuming and impractical. Here we introduce a mapping method\nto identify possible combinations by comparing the dimensionless parameters of\nthe chosen materials with the provided maps and without any transport\ncalculations. Using this approach, we have identified several combinations of\ncore, shell and host materials for which electronic cloaking is achievable. We\nhave optimized the size and doping level of some of these materials\ncombinations to maximize their thermoelectric power factor. Compared to\ntraditional impurity-doped samples, up to 14.50 times improvement in the\nthermoelectric power factor was observed at T=77K.",
        "positive": "Effect of Creep on Corrosion-Induced Cracking: For corrosion-induced cracking in reinforced concrete, naturally occurring\ncorrosion rates are so low that rust accumulates often over tens of years near\nthe surface of the reinforcement bars before sufficient pressure in the\nsurrounding concrete is generated to induce cracking in the concrete cover. To\nspeed up the process, corrosion tests with impressed currents have been\ndeveloped in which the corrosion rate is controlled to be so high that cracking\nof the concrete cover occurs within a few days. Extrapolating the results of\nthese accelerated tests to those of naturally occurring corrosion requires an\nunderstanding of the influence of long-term creep deformations of concrete on\nthe corrosion-induced cracking process. In mathematical models in the\nliterature, creep deformations are often ignored for accelerated but considered\nfor natural corrosion rates in the form of an effective modulus. Here, three\nnumerical models of increasing complexity are proposed with the aim to\ninvestigate the effect of creep on corrosion-induced cracking. The simplest\napproach is based on an uncracked axis-symmetric thick-walled cylinder combined\nwith a plastic limit on the radial pressure-induced by the accumulation of\nrust. The model with intermediate complexity comprises a thick-walled cylinder\nmodel divided into an inner cracked and an outer uncracked layer. The most\ncomprehensive model consists of a thick-walled cylinder discretised by a\nthree-dimensional lattice approach. Basic creep is predicted in all three\napproaches by means of the B3 model developed by Ba\\v{z}ant and co-workers.\nTime dependence of strength of concrete is modelled using fib Model Code\nexpressions. It is shown that for the comprehensive lattice model, creep has\nlimited influence on critical corrosion penetration, which indicates that the\ndependence of the critical corrosion penetration on corrosion rate must have\nother sources."
    },
    {
        "anchor": "Thermodynamic driving force of formation of coherent three-dimensional\n  islands in Stranski-Krastanov growth: The formation of coherent three-dimensional islands in highly mismatched\nepitaxy is discussed in terms of the traditional concept of wetting. It is\nshown that the wetting layer and the 3D islands represent different phases\nwhich cannot be in equilibrium with each other, and the transfer of matter from\nthe stable wetting layer to the 3D islands is thermodynamically unfavored. The\nexperimentally observed critical misfit for coherent 3D islanding to occur and\nthe coexistence of pyramids with discrete heights of two, three, four...\nmonolayers can be explained assuming that the thermodynamic driving force of\nformation of coherent 3D islands on the surface of the wetting layer of the\nsame material is the reduced average adhesion of the islands to that layer and\nthat the islands height is a discrete variable.",
        "positive": "Emergence of hidden phases of methylammonium lead-iodide\n  (CH$_3$NH$_3$PbI$_3$) upon compression: We perform a thorough structural search with the minima hopping method (MHM)\nto explore low-energy structures of methylammonium lead iodide. By combining\nthe MHM with a forcefield, we efficiently screen vast portions of the\nconfigurational space with large simulation cells containing up to 96 atoms.\nOur search reveals two structures of methylammonium iodide perovskite (MAPI)\nthat are substantially lower in energy than the well-studied experimentally\nobserved low-temperature $Pnma$ orthorhombic phase according to density\nfunctional calculations. Both structures have not yet been reported in the\nliterature for MAPI, but our results show that they could emerge as\nthermodynamically stable phases via compression at low temperatures. In terms\nof the electronic properties, the two phases exhibit larger band gaps than the\nstandard perovskite-type structures. Hence, pressure induced phase selection at\ntechnologically achievable pressures (i.e., via thin-film strain) is a route\ntowards the synthesis of several MAPI polymorph with variable band gaps."
    },
    {
        "anchor": "Hyperfine Interactions in USb2 Crystal: The hyperfine interactions at the uranium site in the antiferromagnetic USb2\ncompound were calculated within the density functional theory (DFT) employing\nthe augmented plane wave plus local orbital (APW+lo) method. We investigated\nthe dependence of the nuclear quadruple interactions to the magnetic structure\nin USb2 compound. The investigation were performed applying the so called band\ncorrelated LDA+U theory self consistently. The self consistent LDA+U\ncalculations were gradually added to the performed generalized gradient\napproximation (GGA) including scalar relativistic spin orbit interactions in a\nsecond variation scheme. The result, which is in agreement with experiment,\nshows that the 5f-electrons have the tendency to be hybridized with the\nconduction electrons in the ferromagnetic uranium planes.",
        "positive": "Simulation of X-ray diffraction profiles for bent anisotropic crystals: The equations for calculating diffraction profiles for bent crystals are\nrevisited for both meridional and sagittal bending. Two approximated methods\nfor computing diffraction profiles are treated: multilamellar and\nPenning-Polder. A common treatment of crystal anisotropy is included in these\nmodels. The formulation presented is implemented into the XOP package,\ncompleting and updating the crystal module that simulates diffraction profiles\nfor perfect, mosaic and now distorted crystals by elastic bending."
    },
    {
        "anchor": "Direct observation of a highly spin-polarized organic spinterface at\n  room temperature: The design of large-scale electronic circuits that are entirely\nspintronics-driven requires a current source that is highly spin-polarised at\nand beyond room temperature, cheap to build, efficient at the nanoscale and\nstraightforward to integrate with semiconductors. Yet despite research within\nseveral subfields spanning nearly two decades, this key building block is still\nlacking. We experimentally and theoretically show how the interface between Co\nand phthalocyanine molecules constitutes a promising candidate. Spin-polarised\ndirect and inverse photoemission experiments reveal a high degree of spin\npolarisation at room temperature at this interface. We measured a magnetic\nmoment on the molecules's nitrogen pi orbitals, which substantiates an\nab-initio theoretical description of highly spin-polarised charge conduction\nacross the interface due to differing spinterface formation mechanims in each\nspin channel. We propose, through this example, a recipe to engineer simple\norganic-inorganic interfaces with remarkable spintronic properties that can\nendure well above room temperature.",
        "positive": "Finite-size effects on the ferroelectricity in rhombohedral HfO$_2$: In this work we analyze the finite-size effects on the structural properties\nand on the polarization of the rhombohedral phase of HfO$_2$ subjected to a\nbiaxial compressive strain. We show how the presence of surface charges affects\nthe polarization, leading to a strong reduction with respect to its bulk value.\nThis reduction can be ascribed to two mechanisms: the coupling between\ncompressive strain and the phase-transition order parameter; the changes in the\nferroelectric distortion. We give two alternative explanations of this\nphenomenon: from an atomistic point of view, analyzing the evolution of the\nbond lengths, and from a symmetry-analysis point of view, considering the\nchanges in the amplitude of the symmetry-allowed distortions, when a slab\nconfiguration is considered. These results are independent on the\nslab-thickness in the considered range, suggesting the absence of a critical\nthickness for ferroelectricity in HfO$_2$, in agreement with the proposed\nimproper nature of hafnia ferroelectricity."
    },
    {
        "anchor": "Resolving Few-Layer Antimonene/Graphene Heterostructures: Two-dimensional (2D) antimony (Sb, antimonene) recently attracted interest\ndue to its peculiar electronic properties and its suitability as anode material\nin next generation batteries. Sb however exhibits a large\npolymorphic/allotropic structural diversity, which is also influenced by the\nSb's support. Thus understanding Sb heterostructure formation is key in 2D Sb\nintegration. Particularly 2D Sb/graphene interfaces are of prime importance as\ncontacts in electronics and electrodes in batteries. We thus study here\nfew-layered 2D Sb/graphene heterostructures by atomic-resolution (scanning)\ntransmission electron microscopy. We find the co-existence of two Sb\nmorphologies: First is a 2D growth morphology of layered beta-Sb with\nbeta-Sb(001)||graphene(001) texture. Second are one-dimensional (1D) Sb\nnanowires which can be matched to beta-Sb with beta-Sb[2-21] perpendicular to\ngraphene(001) texture and are structurally also closely related to\nthermodynamically non-preferred cubic Sb(001)||graphene(001). Importantly, both\nSb morphologies show rotational van-der-Waals epitaxy with the graphene\nsupport. Both Sb morphologies are well resilient against environmental bulk\noxidation, although superficial Sb-oxide layer formation merits consideration,\nincluding formation of novel epitaxial Sb2O3(111)/beta-Sb(001)\nheterostructures. Exact Sb growth behavior is sensitive on employed processing\nand substrate properties including, notably, the nature of the support\nunderneath the direct graphene support. This introduces the substrate\nunderneath a direct 2D support as a key parameter in 2D Sb heterostructure\nformation. Our work provides insights into the rich phase and epitaxy landscape\nin 2D Sb and 2D Sb/graphene heterostructures.",
        "positive": "RENiO3 single crystals (RE = Nd, Sm, Gd, Dy, Y, Ho, Er, Lu) grown from\n  molten salts under 2000 bar oxygen-gas pressure: The electronic properties of transition-metal oxides with highly correlated\nelectrons are of central importance in modern condensed matter physics and\nchemistry, both for their fundamental scientific interest, and for their\npotential for advanced electronic applications. The design of materials with\ntailored properties has been, however, restricted by the limited understanding\nof their structure-property relationships, which are particularly complex in\nthe proximity of the regime where localized electrons become gradually mobile.\nRENiO3 perovskites, characterized by the presence of spontaneous metal to\ninsulator transitions, are one of the most widely used model materials for the\ninvestigation of this region in theoretical studies. However, crucial\nexperimental information needed to validate theoretical predictions is still\nlacking due to their challenging high-pressure synthesis, which has prevented\nto date the growth of sizable bulk single crystals with RE different than La,\nPr and Nd. Here we report the first successful growth of single crystals with\nRE = Nd, Sm, Gd, Dy, Y, Ho, Er and Lu and sizes up to ~75 {\\mu}m, grown from\nmolten salts in temperature gradient under 2000 bar oxygen gas pressure. The\ncrystals display regular prismatic shapes with flat facets, and their crystal\nstructures, metal-insulator and antiferromagnetic order transition temperatures\nare in excellent agreement with previously reported values obtained from\npolycrystalline samples. The availability of such crystals opens access to\nmeasurements that have hitherto been impossible to conduct. This should\ncontribute to a better understanding of the fascinating properties of materials\nwith highly correlated electrons, and guide future efforts to engineer\ntransition metal oxides with tailored functional properties."
    },
    {
        "anchor": "Field induced single molecule magnet behavior in Dy-based coordination\n  polymer: A new mononuclear Dysprosium based Coordination Polymer {Dy-CP} was\ninvestigated magnetically using dc and ac magnetic susceptibility. The dc\nmagnetic susceptibility does not exhibit any long-range ordering down to 1.8 K\nand the negative value of Curie Constant (~ - 4 K) indicate the dominance of\nantiferromagnetic interactions between the Dy (III) spins. Ac susceptibility\nexhibits absence of single molecular magnet behavior at zero dc magnetic field\nand shows signal of quantum tunneling magnetization (QTM) below 8 K. However,\non the superimposition of dc magnetic field (3 kOe), frequency dependent\nrelaxation peak emerged at T_f = 5 K and QTM signal suppress at higher fields.\nThe intermediate value of Mydosh parameter calculated from the shift in peak\nposition (T_f) in ac susceptibility reflects the formation of superparamagnetic\nstate. Further, the temperature dependence of Tf is analyzed with Arrhenius and\nCole-Cole plot. The magnetic susceptibility analysis yields characteristics\npre-relaxation factor 1.40x10^(-12) sec and energy barrier {\\Delta}E/k_B = 93.4\nK, indicating the slow spin relaxation. The Cole-Cole fit to the ac\nsusceptibility data shows further evidence for the single ion spin relaxation.\nThus, the magnetic measurements support the single-molecule magnet behavior in\nDy-CP under the application of dc magnetic field.",
        "positive": "Synthesis of InP nanoneedles and their use as Schottky devices: Indium phosphide (InP) nanostructures have been synthesized by means of\ncolloidal chemistry. Under appropriate conditions needle-shaped nanostructures\ncomposed of an In head and an InP tail with lengths up to several micrometers\ncould be generated in a one-pot synthesis. The growth is interpreted in terms\nof simultaneous decomposition of the In precursor and in situ generation of In\nand InP nanostructures. Owing to their specific design such In/InP nanoneedles\nsuit the use as ready-made Schottky transistors. Their transfer and output\ncharacteristics are presented."
    },
    {
        "anchor": "Electronic structure, metamagnetism and thermopower of LaSiFe$_{12}$ and\n  interstitially doped LaSiFe$_{12}$: We present a systematic investigation of the effect of H, B, C, and N\ninterstitials on the electronic, lattice and magnetic properties of\nLa(Fe,Si)$_{13}$ using density functional theory. The parent LaSiFe$_{12}$\nalloy has a shallow, double-well free energy function that is the basis of\nitinerant metamagnetism. On increasing the dopant concentration, the resulting\nlattice expansion causes an initial increase in magnetisation for all\ninterstitials that is only maintained at higher levels of doping in the case of\nhydrogen. Strong s-p band hybridisation occurs at high B,C and N\nconcentrations. We thus find that the electronic effects of hydrogen doping are\nmuch less pronounced than those of other interstitials, and result in the\ndouble-well structure of the free energy function being least sensitive to the\namount of hydrogen. This microscopic picture accounts for the vanishing first\norder nature of the transition by B,C, and N dopants as observed\nexperimentally. We use our calculated electronic density of states for\nLaSiFe$_{12}$ and the hydrogenated alloy to infer changes in magneto-elastic\ncoupling and in phonon entropy on heating through $T_C$ by calculating the\nfermionic entropy due to the itinerant electrons. Lastly, we predict the\nelectron thermopower in a spin-mixing, high temperature limit and compare our\nfindings to recent literature data.",
        "positive": "Unusual plastic deformation and damage features in Titanium:\n  experimental tests and constitutive modeling: In this paper, we present an experimental study on plastic deformation and\ndamage of polycrystalline pure Ti, as well as modeling of the observed\nbehavior. From the mechanical characterization data, it can be concluded that\nthe material displays anisotropy and tension-compression asymmetry. As concerns\ndamage, the X-ray tomography measurements conducted reveal that damage\ndistribution and evolution in this HCP Ti material is markedly different than\nin a typical FCC material such as copper. Stewart and Cazacu (2011) anisotropic\nelastic/plastic damage model is used to describe the behavior. All material\nparameters involved in this model have a clear physical significance, being\nrelated to plastic properties, and are determined based on very few simple\nmechanical tests. It is shown that this model predicts correctly the anisotropy\nin plastic deformation, and its strong influence on damage distribution and\ndamage accumulation in Ti. Specifically, for a smooth axisymmetric specimen\nsubject to uniaxial tension, damage initiates at the center of the specimen and\nis diffuse; the level of damage close to failure is very low. On the other\nhand, for a notched specimen subject to the same loading, the model predicts\nthat damage initiates at the outer surface of the specimen, and further grows\nfrom the outer surface to the center of the specimen, which corroborates with\nthe in-situ tomography data."
    },
    {
        "anchor": "High CO tolerance of Pt/Ru nano-catalyst: insight from first principles\n  calculation: Density functional theory based calculations of the energetics of adsorption\nand diffusion of CO on Pt islets and on the Ru(0001) substrate show that CO has\nthe lowest adsorption energy at the center of the islet, and its bonding\nincreases as it moves to the edge of the island and further onto the substrate.\nActivation energy barriers for CO diffusion from the islet to the Ru surface\nare found to be lower than 0.3 eV making the process feasible and leading to\nthe conclusion that this hydrogen oxidation catalyst is CO tolerant because of\nthe spillover of CO from active Pt sites to the Ru substrate. We present the\nrationale for this effect using insights from detailed electronic structure\ncalculations.",
        "positive": "Large ground state magnetic moment and magnetocaloric effect in\n  Ni2Mn1.4In0.6: A large conventional magnetocaloric effect at the second order magnetic\ntransition in cubic Ni2Mn1.4In0.6 Heusler alloy is reported. The isothermal\nmagnetization at 2K shows a huge ground state magnetic moment of about 6.17\n{\\mu}B/f.u. The theoretical calculations show that the origin of the large\nmagnetic moment in cubic Ni2Mn1.4In0.6 results from the strong ferromagnetic\ninteraction between Mn- Ni and Mn-Mn sublattices. The experimental magnetic\nmoment is in excellent agreement with the moment calculated from the theory.\nThe large magnetic moment gives rise to considerably high adiabatic temperature\nand entropy changes at the magnetic transition. The present study opens up the\npossibility to explore cubic Heusler alloys for magnetocaloric applications."
    },
    {
        "anchor": "Negative Magnetization and Magnetic Ordering of Rare Earth and\n  Transition Metal Sublattices in NdFe0.5Cr0.5O3: We investigate the effect of alloying at the 3d transition metal site of a\nrare-earth-transition metal oxide, by considering NdFe0.5Cr0.5O3 alloy with two\nequal and random distribution of 3d ions, Cr and Fe, interacting with an early\n4f rare earth ion, Nd. Employing temperature- and field-dependent magnetization\nmeasurements, temperature-dependent x-ray diffraction, neutron powder\ndiffraction, and Raman spectroscopy, we characterize its structural and\nmagnetic properties. Our study reveals bipolar magnetic switching (arising from\nnegative magnetization) and magnetocaloric effect which underline the potential\nof the studied alloy in device application. The neutron diffraction study shows\nthe absence of spin reorientation transition over the entire temperature range\nof 1.5-320 K, although both parent compounds exhibit spin orientation\ntransition. We discuss the microscopic origin of this curious behavior. The\nneutron diffraction results also reveal the ordering of Nd spins at an\nunusually high temperature of about 40 K, which is corroborated by Raman\nmeasurements.",
        "positive": "High Performance X-Ray Transmission Windows Based on Graphenic Carbon: A novel x-ray transmission window based on graphenic carbon has been\ndeveloped with superior performance compared to beryllium transmission windows\nthat are currently used in the field. Graphenic carbon in combination with an\nintegrated silicon frame allows for a window design which does not use a\nmechanical support grid or additional light blocking layers. Compared to\nberyllium, the novel x-ray transmission window exhibits an improved\ntransmission in the low energy region ($0.1 hbox{keV}-3 hbox{keV}$ ) while\ndemonstrating excellent mechanical stability, as well as light and vacuum\ntightness. Therefore, the newly established graphenic carbon window, can\nreplace beryllium in x-ray transmission windows with a nontoxic and abundant\nmaterial. Index terms: Beryllium, Carbon, Graphene, Thin films, X-ray\napplications, X-ray detectors"
    },
    {
        "anchor": "Polarization-driven band topology evolution in twisted MoTe$_2$ and\n  WSe$_2$: Motivated by recent experimental observations of opposite Chern numbers in\n$R$-type twisted MoTe$_2$ and WSe$_2$ homobilayers, we perform large-scale\ndensity-functional-theory (DFT) calculations with machine learning force fields\nto investigate moir\\'e band topology from large to small twist angels in both\nmaterials. We find that the Chern numbers of the moir\\'e frontier bands change\nsign as a function of twist angle, and this change is driven by the competition\nbetween the in-plane piezoelectricity and the out-of-plane ferroelectricity.\nOur large-scale calculations, enabled by machine learning methods, reveal\ncrucial insights into interactions across different scales in twisted bilayer\nsystems. The interplay between atomic-level relaxation effects and\nmoir\\'e-scale electrostatic potential variation opens new avenues for the\ndesign of intertwined topological and correlated states.",
        "positive": "Resistance minimum and electrical conduction mechanism in\n  polycrystalline CoFeB thin films: The temperature dependent resistance $R$($T$) of polycrystalline\nferromagnetic CoFeB thin films of varying thickness are analyzed considering\nvarious electrical scattering processes. We observe a resistance minimum in\n$R$($T$) curves below $\\simeq$ 29 K, which can be explained as an effect of\nintergranular Coulomb interaction in a granular system. The structural and\nCoulomb interaction related scattering processes contribute more as the film\nthickness decreases implying the role of disorder and granularity. Although the\nmagnetic contribution to the resistance is the weakest compared to these two,\nit is the only thickness independent process. On the contrary, the negative\ncoefficient of resistance can be explained by electron interaction effect in\ndisordered amorphous films."
    },
    {
        "anchor": "Database of 2D hybrid perovskite materials: open-access collection of\n  crystal structures, band gaps and atomic partial charges predicted by machine\n  learning: We describe a first open-access database of experimentally investigated\nhybrid organic-inorganic materials with two-dimensional (2D) perovskite-like\ncrystal structure. The database includes 515 compounds, containing 180\ndifferent organic cations, 10 metals (Pb, Sn, Bi, Cd, Cu, Fe, Ge, Mn, Pd, Sb)\nand 3 halogens (I, Br, Cl) known so far and will be regularly updated. The\ndatabase contains a geometrical and crystal chemical analysis of the\nstructures, which are useful to reveal quantitative structure-property\nrelationships for this class of compounds. We show that the penetration depth\nof spacer organic cation into the inorganic layer and M-X-M bond angles\nincrease in the number of inorganic layers (n). The machine learning model is\ndeveloped and trained on the database, for the prediction of a band gap with\naccuracy within 0.1 eV. Another machine learning model is trained for the\nprediction of atomic partial charges with accuracy within 0.01 e. We show that\nthe predicted values of band gaps decrease with an increase of the n and with\nan increase of M-X-M angles for single-layered perovskites. In general, the\nproposed database and machine learning models are shown to be useful tools for\nthe rational design of new 2D hybrid perovskite materials.",
        "positive": "Pixel-wise classification in graphene-detection with tree-based machine\n  learning algorithms: Mechanical exfoliation of graphene and its identification by optical\ninspection is one of the milestones in condensed matter physics that sparked\nthe field of 2D materials. Finding regions of interest from the entire sample\nspace and identification of layer number is a routine task potentially amenable\nto automatization. We propose supervised pixel-wise classification methods\nshowing a high performance even with a small number of training image datasets\nthat require short computational time without GPU. We introduce four different\ntree-based machine learning algorithms -- decision tree, random forest, extreme\ngradient boost, and light gradient boosting machine. We train them with five\noptical microscopy images of graphene, and evaluate their performances with\nmultiple metrics and indices. We also discuss combinatorial machine learning\nmodels between the three single classifiers and assess their performances in\nidentification and reliability. The code developed in this paper is open to the\npublic and will be released at github.com/gjung-group/Graphene_segmentation."
    },
    {
        "anchor": "Site-specific symmetry sensitivity of angle-resolved photoemission\n  spectroscopy in layered palladium diselenide: Two-dimensional (2D) materials with puckered layer morphology are promising\ncandidates for next-generation opto-electronics devices owing to their\nanisotropic response to external perturbations and wide band gap tunability\nwith the number of layers. Among them, PdSe2 is an emerging 2D transition-metal\ndichalcogenide with band gap ranging from 1.3 eV in the monolayer to a\npredicted semimetallic behavior in the bulk. Here we use angle-resolved\nphotoemission spectroscopy to explore the electronic band structure of PdSe2\nwith energy and momentum resolution. Our measurements reveal the semiconducting\nnature of the bulk. Furthermore, constant binding-energy maps of reciprocal\nspace display a remarkable site-specific sensitivity to the atomic arrangement\nand its symmetry. Supported by density functional theory calculations, we\nascribe this effect to the inherent orbital character of the electronic band\nstructure. These results not only provide a deeper understanding of the\nelectronic configuration of PdSe2, but also establish additional capabilities\nof photoemission spectroscopy.",
        "positive": "Structure of Non-Solid Matter in Equilibrium State under NVT ensemble:\n  New Insight from Spatial Constraint: When non-solid matter (e.g., liquids or gas) is under constant volume V and\ndensity rho (e.g., in rigid box), spatial positions for their constituents are\nrestricted by these conditions. We recently focus on the role of constraint in\nclassical statistical thermodynamics, and find how spatial constraint connects\nwith equilibrium properties for crystalline solids, which has not been\nclarified so far. The present study extend the idea to non-solid matter under\nNVT ensemble in classical systems. We provide explicit representation of\ncanonical average of radial distribution function in terms of spatial\nconstraint, which can be well characterized by a single special microscopic\nstate on configuration space called projection state for non-solid matter. We\ndemonstrate that the special microscopic state can be numerically constructed\nfor a finite number of particles."
    },
    {
        "anchor": "Relaxation time of weakly interacting superparamagnets: The relaxation time of weakly interacting classical spins is calculated by\nintroducing the averages of the local dipolar field, obtained by thermodynamic\nperturbation theory, in a rigorous expression for the single-spin\nthermoactivation rate in a weak but arbitrarily oriented field. At low\ntemperatures the non-trivial dependence of the superparamagnetic blocking on\nthe damping coefficient, numerically found by Berkov and Gorn, is reproduced by\nour model and interpreted in terms of the deviations from uniaxial anisotropy\nassociated to the transversal component of the dipolar field acting on each\nspin.",
        "positive": "Effects of UV radiation on the charge trapping capability of PET: Poly(ethylene terephthalate) (PET), as most dielectric materials, is able to\nretain space charge in traps. This allows the material to attain an\nalmost-permanent polarization when space charge is displaced by an external\nelectric field or it is injected from an electrode. We have studied the\ninfluence of UV irradiation on the charge trapping capability of PET in samples\nexposed for different periods of time, up to 10 weeks. The pulsed\nelectro-acoustic technique (PEA) has been used to determine the charge profile.\nThe injected charge that the material is able to retain on the irradiated\nsurface increases with irradiation time. This indicates the formation of new\ntraps. An extensive characterization of these localized states has been\nperformed by thermally stimulated depolarization currents (TSDC) technique.\nParameters of charge relaxation kinetics have been obtained fitting spectra of\nthe $\\rho_c$ peak, related to injected charge, to the general order kinetics\nmodel. A relaxation map analysis shows that relaxation times become more\ndistributed and the activation energy decreases as irradiation time is\nincreased. The activation energy decreases approximately by 10% after 10 weeks\nof exposition. These results show that UV irradiation creates additional traps\non the treated surface, which agrees with PEA results, and that these traps are\nshallower and their energy depth distribution is wider than in the case of\npre-existing traps."
    },
    {
        "anchor": "Deformation twins as a probe for tribologically induced stress states: Friction and wear of metals are critically influenced by the microstructures\nof the bodies constituting the tribological contact. Understanding the\nmicrostructural evolution taking place over the lifetime of a tribological\nsystem therefore is crucial for strategically designing tribological systems\nwith tailored friction and wear properties. Here, we focus on\nsingle-crystalline CoCrFeMnNi that is prone to form twins at room temperature.\nDeformation twins feature a pronounced orientation dependence with a\ntension-compression anisotropy, a distinct strain release in an extended volume\nand robust onset stresses. This makes deformation twinning an ideal probe to\nexperimentally investigate the complex stress fields occurring in a\ntribological contact. Our results clearly show a grain orientation dependence\nof twinning under tribological load. Unexpectedly, neither the crystal\ndirection parallel to the sliding nor the normal direction are solely decisive\nfor twinning. This experimental approach is ideal to experimentally validate\ntribological stress field models, as is demonstrates here.",
        "positive": "Synthesis of narrow SnTe nanowires using alloy nanoparticles: Topological crystalline insulator tin telluride (SnTe) provides a rich\nplayground to examine interactions of correlated electronic states, such as\nferroelectricity, topological surface states, and superconductivity. Making\nSnTe into nanowires further induces novel electronic states due to\none-dimensional (1D) confinement effects. Thus, for transport measurements,\nSnTe nanowires must be made narrow in their diameters to ensure the 1D\nconfinement and phase coherence of the topological surface electrons. This\nstudy reports a facile growth method to produce narrow SnTe nanowires with a\nhigh yield using alloy nanoparticles as growth catalysts. The average diameter\nof the SnTe nanowires grown using the alloy nanoparticles is 85 nm, nearly a\nfactor of three reduction from the previous average diameter of 240 nm using\ngold nanoparticles as growth catalysts. Transport measurements reveal the\neffect of the nanowire diameter on the residual resistance ratio and\nmagnetoresistance. Particularly, the ferroelectric transition temperature for\nSnTe is observed to change systematically with the nanowire diameter. In situ\ncryogenic cooling of narrow SnTe nanowires in a transmission electron\nmicroscope directly reveals the cubic to rhombohedral structural transition,\nwhich is associated with the ferroelectric transition. Thus, these narrow SnTe\nnanowires represent a model system to study electronic states arising from the\n1D confinement, such as 1D topological superconductivity as well as a potential\nmulti-band superconductivity."
    },
    {
        "anchor": "Machine learning the DFT potential energy surface for inorganic halide\n  perovskite CsPbBr$_3$: Structural phase transitions as a function of temperature dictate the\nstructure--functionality relationships in many technologically important\nmaterials. Harmonic Hamiltonians have proven successful in predicting the\nvibrational properties of many materials. However, they are inadequate for\nmodeling structural phase transitions in crystals with potential energy\nsurfaces that are either strongly anharmonic or no\\ n-convex with respect to\ncollective atomic displacements or homogeneous strains. In this paper we\ndevelop a framework to express highly anharmonic first-principles potential\nenergy surfaces as polynomials of collective cluster deformati\\ ons. We further\nadapt the approach to a nonlinear extension of the cluster expansion formalism\nthrough the use of an artificial neural net model. The machine learning models\nare trained on a large database of first-principles calculations and are shown\nto reproduce the potential energy surface with l\\ ow error.",
        "positive": "Critical Separation of Clusters During Physical Vapor Deposition: The critical separation of clusters, corresponding to the maximum density of\nclusters, affects growth characteristics during physical vapor deposition\n(PVD). In particular, this separation can affect surface smoothness in growing\nsingle-crystalline films, grain size distribution in growing polycrystalline\nfilms, and diameter in growing nanorods. This Letter reports a theoretical\nexpression of the critical separation as a function of deposition conditions\nand accompanying verifications using lattice kinetic Monte Carlo (MC)\nsimulations of PVD on Cu{111}. In contrast to existing theories, the\ntheoretical expression in this Letter is (1) closed-form, (2) in better\nagreement with the MC simulations than the lattice approximation and (3) in\nbetter agreement with the MC simulations than the mean field approximation when\nthe critical separation is large- larger than 25 nm for PVD on Cu{111}."
    },
    {
        "anchor": "Self-doping effect in confined copper selenide semiconducting quantum\n  dots for efficient photoelectrocatalytic oxygen evolution: Self-doping can not only suppress the photogenerated charge recombination of\nsemiconducting quantum dots by self-introducing trapping states within the\nbandgap, but also provide high-density catalytic active sites as the\nconsequence of abundant non-saturated bonds associated with the defects. Here,\nwe successfully prepared semiconducting copper selenide (CuSe) confined quantum\ndots with abundant vacancies and systematically investigated their\nphotoelectrochemical characteristics. Photoluminescence characterizations\nreveal that the presence of vacancies reduces the emission intensity\ndramatically, indicating a low recombination rate of photogenerated charge\ncarriers due to the self-introduced trapping states within the bandgap. In\naddition, the ultra-low charge transfer resistance measured by electrochemical\nimpedance spectroscopy implies the efficient charge transfer of CuSe\nsemiconducting quantum dots-based photoelectrocatalysts, which is guaranteed by\nthe high conductivity of their confined structure as revealed by\nroom-temperature electrical transport measurements. Such high conductivity and\nlow photogenerated charge carriers recombination rate, combined with\nhigh-density active sites and confined structure, guaranteeing the remarkable\nphotoelectrocatalytic performance and stability as manifested by\nphotoelectrocatalysis characterizations. This work promotes the development of\nsemiconducting quantum dots-based photoelectrocatalysis and demonstrates CuSe\nsemiconducting quantum confined catalysts as an advanced photoelectrocatalysts\nfor oxygen evolution reaction.",
        "positive": "Contrasting the magnetic response between magnetic-glass and reentrant\n  spin-glass: Magnetic-glass is a recently identified phenomenon in various classes of\nmagnetic systems undergoing a first order magnetic phase transition. We shall\nhighlight here a few experimentally determined characteristics of\nmagnetic-glass and the relevant set of experiments, which will enable to\ndistinguish a magnetic-glass unequivocally from the well known phenomena of\nspin-glass and reentrant spin-glass."
    },
    {
        "anchor": "Topological nature and the multiple Dirac cones hidden in Bismuth\n  high-Tc superconductors: Recent theoretical studies employing density-functional theory have predicted\nBaBiO$_{3}$ (when doped with electrons) and YBiO$_{3}$ to become a topological\ninsulator (TI) with a large topological gap (~ 0.7 eV). This, together with the\nnatural stability against surface oxidation, makes the Bismuth-Oxide family of\nspecial interest for possible applications in quantum information and\nspintronics. The central question, we study here, is whether the hole-doped\nBismuth Oxides, i.e. Ba$_{1-x}$K$_{x}$BiO$_{3}$ and\nBaPb$_{1-x}$Bi$_{x}$O$_{3}$, which are \"high-Tc\" bulk superconducting near 30\nK, additionally display in the further vicinity of their Fermi energy $E_{F}$ a\ntopological gap with a Dirac-type of topological surface state. Our electronic\nstructure calculations predict the K-doped family to emerge as a TI, with a\ntopological gap above $E_{F}$. Thus, these compounds can become superconductors\nwith hole-doping and potential TIs with additional electron doping.\nFurthermore, we predict the Bismuth-Oxide family to contain an additional Dirac\ncone below $E_{F}$ for further hole doping, which manifests these systems to be\ncandidates for both electron- and hole-doped topological insulators.",
        "positive": "Thermodynamic Self Assembly of Two-Dimensional pi-Conjugated\n  Metal-Porphyrin Covalent Organic Frameworks by On-Site Equilibrium\n  Polymerization: Two dimensional pi conjugated metal porphyrin covalent organic frameworks\nwere produced in aqueous solution on an iodine-modified Au(111) surface by on\nsite azomethine coupling of Fe(III) 5,10,15,20 tetrakis(4 aminophenyl)porphyrin\n(FeTAPP) with terephthal dicarboxaldehyde and investigated in detail using\nin-situ scanning tunneling microscopy. Mixed covalent organic porphyrin\nframeworks consisting of FeTAPP and metal-free TAPP (H2TAPP) were prepared\nthrough simultaneous adsorption in a mixed solution as well as partial\nreplacement of FeTAPP by H2TAPP in an as prepared metal porphyrin framework. In\nthe mixed framework, the relative distribution of FeTAPP to H2TAPP was not\nrandom and revealed a preference for homo-connection rather than\nheteroconnection. The construction of substrate-supported, pi conjugated\ncovalent frameworks from multiple building blocks, including metal centers,\nwill be of significant utility in the design of functional molecular\nnanoarchitectures."
    },
    {
        "anchor": "First-principles electron-phonon interactions and electronic transport\n  in large-angle twisted bilayer graphene: Twisted bilayer graphene (tBLG) has emerged as an exciting platform for novel\ncondensed matter physics. However, electron-phonon ($e$-ph) interactions in\ntBLG and their effects on electronic transport are not completely understood.\nHere we show first-principles calculations of $e$-ph interactions and\nresistivity in commensurate tBLG with large twist angles of 13.2 and 21.8\ndegrees. These calculations overcome key technical barriers, including large\nunit cells of up to 76 atoms, Brillouin-zone folding of the $e$-ph\ninteractions, and unstable lattice vibrations due to the AA-stacked domains. We\nshow that $e$-ph interactions due to layer-breathing (LB) phonons enhance\nintervalley scattering in large-angle tBLG. This interaction effectively\ncouples the two layers, which are otherwise electronically decoupled at such\nlarge twist angles. As a result, the phonon-limited resistivity in tBLG\ndeviates from the temperature-linear trend characteristic of monolayer graphene\nand tBLG near the magic angle. Taken together, our work quantifies $e$-ph\ninteractions and scattering mechanisms in tBLG, revealing subtle interlayer\ncoupling effects at large twist angles.",
        "positive": "General Lattice Model of Gradient Elasticity: New lattice model for the gradient elasticity is suggested. This lattice\nmodel gives a microstructural basis for second-order strain-gradient elasticity\nof continuum that is described by the linear elastic constitutive relation with\nthe negative sign in front of the gradient. Moreover the suggested lattice\nmodel allows us to have a unified description of gradient models with positive\nand negative signs of the strain gradient terms. Possible generalizations of\nthis model for the high-order gradient elasticity and three-dimensional case\nare also suggested."
    },
    {
        "anchor": "The Yellow Excitonic Series of Cu2O Revisited by Lyman Spectroscopy: We report on the observation of the yellow exciton Lyman series up to the\nfourth term in Cu2O by time-resolved mid-infrared spectroscopy. The dependence\nof the oscillator strength on the principal quantum number n can be well\nreproduced using the hydrogenic model including an AC dielectric constant, and\nprecise information on the electronic structure of the 1s exciton state can be\nobtained. A Bohr radius a_{1s}=7.9 A and a 1s-2p transition dipole moment\n\\mu_{1s-2p}= 4.2 eA were found.",
        "positive": "Super-stretchable borophene and its stability under straining: Recent success in synthesizing two-dimensional borophene on silver substrate\nattracts strong interest in exploring its possible extraordinary physical\nproperties. By using the density functional theory calculations, we show that\nborophene is highly stretchable along the transverse direction. The\nstrain-to-failure in the transverse direction is nearly twice as that along the\nlongitudinal direction. The straining induced flattening and subsequent stretch\nof the flat borophene are accounted for the large strain-to-failure for tension\nin the transverse direction. The mechanical properties in the other two\ndirections exhibit strong anisotropy. Phonon dispersions of the strained\nborophene monolayers suggest that negative frequencies are presented, which\nindicates the instability of free-standing borophene even under high tensile\nstress."
    },
    {
        "anchor": "Understanding creep of a single-crystalline Co-Al-W-Ta superalloy by\n  studying the deformation mechanism, segregation tendency and stacking fault\n  energy: A systematic study of the compression creep properties of a\nsingle-crystalline Co-base superalloy (Co-9Al-7.5W-2Ta) was conducted at 950\n{\\deg}C, 975 {\\deg}C and 1000 {\\deg}C to reveal the influence of temperature\nand the resulting diffusion velocity of solutes like Al, W and Ta on the\ndeformation mechanisms. Two creep rate minima are observed at all temperatures\nindicating that the deformation mechanisms causing these minima are quite\nsimilar. Atom-probe tomography analysis reveals elemental segregation to\nstacking faults, which had formed in the $\\gamma\\prime$ phase during creep.\nDensity-functional-theory calculations indicate segregation of W and Ta to the\nstacking fault and an associated considerable reduction of the stacking fault\nenergy. Since solutes diffuse faster at a higher temperature, segregation can\ntake place more quickly. This results in a significantly faster softening of\nthe alloy, since cutting of the $\\gamma\\prime$ precipitate phase by partial\ndislocations is facilitated through segregation already during the early stages\nof creep. This is confirmed by transmission electron microscopy analysis.\nTherefore, not only the smaller precipitate fraction at higher temperatures is\nresponsible for the worse creep properties, but also faster diffusion-assisted\nshearing of the $\\gamma\\prime$ phase by partial dislocations. The understanding\nof these mechanisms will help in future alloy development by offering new\ndesign criteria.",
        "positive": "NMR and the antiferromagnetic crystal phase regions in rapidly quenched\n  ribbons and in alloys of the type $Cu-Mn-Al$: It was shown that anomalous resistivity behavior of the $Cu-Mn-Al$ ribbons is\nexplained by the s-d interaction between conduction electrons and the clustered\nMn atoms. While nuclear magnetic resonance measurements show the\nantiferromagnetic and ferromagnetic clusters of Mn atom coexisting without\nlong-range order, it is an interesting problem to study magnetic resonance\nproperties also for the antiferromagnetic crystal phase regions (which have\nlong-range order for larger regions) and which may also occur in these ribbons.\nThe Heusler Type $Cu-Mn-Al$ Alloy has a composition half way between\n$Cu_{2}MnAl$ and $Cu_{3}Al$. Electron microscopy of the premartensitic $\\beta\nCu-Zn-Al$ alloy has shown that the $\\beta Cu-Zn-Al$ alloy quenched from high\ntemperature has the electron diffraction patterns of this alloy well explained\nby the model with the existence of small particles with an orthorhombic\nstructure. It was noted that an important aspect of improvement in the material\nproperties is to create a nanostructured state in matrix, which has significant\nadvantages in magnetic and mechanical characteristics in contrast to the bulk\nmaterials in crystalline or amorphous state. It is an interesting problem to\nstudy magnetic resonance properties not only for the Mn atoms and clusters\nwithout long-range order but also for the antiferromagnetic crystal phase\nregions (which have long-range order for larger regions) which may also occur\nin ribbons. This is the aim of our paper."
    },
    {
        "anchor": "Jahn-Teller distortion induced magnetic phase transition in cubic\n  BaFeO$_{3}$: Using density functional theory (DFT) with local density approximation (LDA)\nand generalized gradient approximation (GGA) correlation functionals, the\nelectronic and magnetic structures of cubic BaFeO$_{3}$ in the ferromagnetic\n(FM) and antiferromagnetic (AFM) states are studied. Our LDA/GGA and\nLDA$+U$/GGA$+U$ results show that cubic BFO has a FM ground state, in agreement\nwith recent experimental works. Two types of Jahn-Teller (JT) distortions,\ndenoted as JT1 and JT2, are considered. We find FM to ferrimagnetic (FIM) and\nFM to AFM magnetic phase transitionn in the JT1 and JT2 type of distortions,\nrespectively. Larger strains are required for the FM-AFM transition as compared\nto the FM-FIM. DFT$+U$ calculations also show that the magnetic moments\ndramatically decrease at large strains due to strong overlapping between the Fe\nand O atoms. The origins of these transitions is discussed in terms of a\ncompetition between double exchange and superexchange interactions. Oxygen and\nFe displacements are therefore responsible for the magnetic phase transitions\nand the reduction of the magnetic moments.",
        "positive": "A New Approach to Phonon Anharmonicity: An approach to compute the anharmonic peaks of the phonon dispersion curves\nthrough the ab initio calculated Hellmann-Feynman forces from a series of\nsupercells with realistic atomic displacements of all atoms, which correspond\nto a given temperature, is reported. Obtained phonon dispersion bands are able\nto represent the positions and shapes of the anharmonic peaks. As example, the\napproach to cubic PbTe and perovskite MgSiO3 crystals is applied."
    },
    {
        "anchor": "Power law statistics of avalanches in martensitic transformation: We devise a two dimensional model that mimics the recently observed power law\ndistributions for the amplitudes and durations of the acoustic emission signals\nobserved during martensitic transformation [ Vives {\\it et al}, Phys. Rev.\nLett. {\\bf 72}, 1694 (1994)]. We include a threshold mechanism arising from the\nathermal nature of transformation, long-range interaction between the\ntransformed domains, inertial effects, and dissipation arising due to the\nmotion of the interface. The model exhibits thermal hysteresis of the\ntransformation, and more importantly, it shows that the energy is released in\nthe form of avalanches with power law distributions for their amplitudes and\ndurations. Computer simulations also reveal morphological features similar to\nthose observed in real systems.",
        "positive": "Multi-scale modeling of folic acid-functionalized TiO$_{2}$\n  nanoparticles for active targeting of tumor cells: Strategies based on the active targeting of tumor cells are emerging as smart\nand efficient nanomedical procedures. Folic acid (FA) is a vitamin and a\nwell-established tumor targeting agent because of its strong affinity for the\nfolate receptor (FR), which is an overexpressed protein on the cell membranes\nof the tumor cells. FA can be successfully anchored to several nanocarriers,\nincluding inorganic nanoparticles (NPs) based on transition metal oxides. Among\nthem, TiO$_{2}$ is extremely interesting because of its excellent\nphotoabsorption and photocatalytic properties, which can be exploited in\nphotodynamic therapy. However, it is not yet clear in which respects direct\nanchoring of FA to the NP or the use of spacers, based on polyethylene glycol\n(PEG) chains, are different and whether one approach is better than the other.\nIn this work, we combine Quantum Mechanics (QM) and Classical Molecular\nDynamics (MD) to design and optimize the FA functionalization on bare and\nPEGylated TiO$_{2}$ models and to study the dynamical behavior of the resulting\nnanoconjugates in pure water environment and in physiological conditions. We\nobserve that they are chemically stable, even under the effect of increasing\ntemperature (up to 500 K). Using the results from long MD simulations (100 ns)\nand from free energy calculations, we determine how the density of FA molecules\non the TiO$_{2}$ NP and the presence of PEG spacers impact on the actual\nexposure of the ligands, especially by affecting the extent of FA-FA\nintermolecular interactions, which are detrimental for the targeting ability of\nFA towards the folate receptor. This analysis provides a solid and rational\nbasis for experimentalists to define the optimal FA density and the more\nappropriate mode of anchoring to the carrier, according to the final purpose of\nthe nanoconjugate."
    },
    {
        "anchor": "Proton channeling through long chiral carbon nanotubes: the rainbow\n  route to equilibration: In this work we investigate the rainbows appearing in channeling of 1 GeV\nprotons through the long (11, 9) single-wall carbon nanotubes. The nanotube\nlength is varied from 10 to 500 micrometers. The angular distributions of\nchanneled protons are computed using the numerical solution of the proton\nequations of motion in the transverse plane and the Monte Carlo method. Each\nrainbow is characterized by a sharp decrease of the proton yield on its large\nangle side. As the nanotube length increases, the number of rainbows increases\nand the average distance between them decreases in an easily predictable way.\nWhen the average distance between the rainbows becomes smaller than the\nresolution of the angular distribution, one cannot distinguish between the\nadjacent rainbows, and the angular distribution becomes equilibrated. We call\nthis route to equilibration the rainbow route to equilibration. This work is a\ndemonstration of how a simple one-dimensional bound dynamic system can exhibit\na complex collective behavior.",
        "positive": "Mechanical behavior, enhanced dc resistivity, energy band gap and high\n  temperature magnetic properties of Y-substituted Mg-Zn ferrites: We report the synthesis of Y-substituted Mg-Zn ferrites using conventional\nstandard ceramic technique. XRD patterns confirm the single phase cubic spinel\nstructure up to x = 0.03 and appearance of a secondary phase of YFeO3for higher\nY contents. FESEM images depict the distribution of grains and EDS spectra\nconfirmed the absence of any unwanted element. Completion of solid state\nreaction and formation of spinel structure has been revealed from FTIR spectra.\nThe FTIR data along with lattice constant, bulk density and porosity were\nfurther used to calculate the stiffness constant (Cij), elastic constant and\nDebye temperatures. Mechanical stability of all studied compositions is\nconfirmed from Cij using Born stability conditions. Brittleness and isotropic\nnature are also confirmed using Poisson ratio and anisotropy constants,\nrespectively. The enhancement of dc electrical resistivity with Y content is\nobserved. The energy band gap (increased with Y contents) is found in good\nagreement with dc electrical resistivity. Ferrimagnetic to paramagnetic phase\nchange has been observed from the field dependent high temperature\nmagnetization curves. The magnetic moments and saturation magnetization were\nfound to be decreased with increasing temperature. The Curie temperature (Tc)\nhas been measured from temperature dependent magnetic moment (M-T) and initial\npermeability and found to be in good agreement with each other. Decrease in Tc\nwith Y content is due to redistribution of cations and weakening of the\nexchange coupling constant. The magnetic phase transition has been analyzed by\nArrott plot and found to have second order phase transition. The dc resistivity\nendorses the prepared ferrites are suitable for high frequency and high\ntemperature magnetic device applications as well."
    },
    {
        "anchor": "Dislocation patterning in a 2D continuum theory of dislocations: Understanding the spontaneous emergence of dislocation patterns during\nplastic deformation is a long standing challenge in dislocation theory. During\nthe past decades several phenomenological continuum models of dislocation\npatterning were proposed, but few of them (if any) are derived from microscopic\nconsiderations through systematic and controlled averaging procedures. In this\npaper we present a 2D continuum theory that is obtained by systematic averaging\nof the equations of motion of discrete dislocations. It is shown that in the\nevolution equations of the dislocation densities diffusion like terms neglected\nin earlier considerations play a crucial role in the length scale selection of\nthe dislocation density fluctuations. It is also shown that the formulated\ncontinuum theory can be derived from an averaged energy functional using the\nframework of phase field theories. However, in order to account for the flow\nstress one has in that case to introduce a nontrivial dislocation mobility\nfunction, which proves to be crucial for the instability leading to patterning.",
        "positive": "The Linear US-uP Relation in Shock-Wave Physics: A linear relation between shock velocity US and particle velocity UP is often\nregarded as the \"typical\" or \"standard\" material response in the shock-wave\nliterature. It has even been proposed that this linearity follows from some\nkind of universal equation of state (EOS) principle. This report presents a\ntheoretical analysis of this issue and a survey of the Hugoniot data for all\nthe elements. It demonstrates that linearity follows from the fact that US-UP\nplots are rather insensitive to material properties, not from any universal\nEOS. The effects of pressure and material properties on the shock response are\nmore easily seen and analyzed by plotting UF = US - UP as a function of UP. The\ndata survey shows that linear behavior is only observed in 20% of all the\nelements and is not at all universal."
    },
    {
        "anchor": "Interplay of Chemical Bonding and Magnetism in Fe_4N, Fe_3N, Fe_2N: Using spin density functional theory we have carried out a comparative study\nof chemical bonding and magnetism in Fe_4N, Fe_3N and Fe_2N. All of these\ncompounds form close packed Fe lattices, while N occupies octahedral\ninterstitial positions. High spin fcc Fe and hypothetical FeN with rock salt\nstructure have been included in our study as reference systems. We find strong,\ncovalent Fe-N bonds as a result of a substantial \\sigma-type p-d hybridisation,\nwith some charge transfer to N. Those Fe d orbitals which contribute to the p-d\nbonds, do no longer participate in the exchange splitting of the Fe d bands.\nBecause of the large exchange fields, the majority spin d bands are always\nfully occupied, while the minority spin d bands are close to half-filling, thus\noptimizing the Fe d-d covalent bonding. As a consequence, in good approximation\nthe individual Fe moments decrease in steps of 0.5 \\mu_B from fcc iron (2.7\n\\mu_B) via Fe_4N (2.7 and 1.97 mu_B}), \\chem{Fe_3N} (1.99 \\mu_B) to \\zeta -\nFe_2N (1.43 \\mu_B).",
        "positive": "Critical mode and band-gap-controlled bipolar thermoelectric properties\n  of SnSe: The reliable calculation of electronic structures and understanding of\nelectrical properties depends on an accurate model of the crystal structure.\nHere, we have reinvestigated the crystal structure of the high-zT\nthermoelectric material tin selenide, SnSe, between 4 and 1000 K using\nhigh-resolution neutron powder diffraction. Symmetry analysis reveals the\npresence of four active structural distortion modes, one of which is found to\nbe active over a relatively wide range of more than +/-200 K around the\nsymmetry-breaking Pnma-Cmcm transition at 800 K. Density functional theory\ncalculations on the basis of the experimental structure parameters show that\nthe unusual, step-like temperature dependencies of the electrical transport\nproperties of SnSe are caused by the onset of intrinsic bipolar conductivity,\namplified and shifted to lower temperatures by a rapid reduction of the band\ngap between 700 and 800 K. The calculated band gap is highly sensitive to small\nout-of-plane Sn displacements observed in the diffraction experiments. SnSe\nwith a sufficiently controlled acceptor concentration is predicted to produce\nsimultaneously a large positive and a large negative Seebeck effect along\ndifferent crystal directions."
    },
    {
        "anchor": "Unraveling the Complexity of Metal Ion Dissolution: Insights from Hybrid\n  First-Principles/Continuum Calculations: The study of ion dissolution from metal surfaces has a long-standing history,\nwherein the gradual dissolution of solute atoms with increasing electrode\npotential, leading to their existence as ions in the electrolyte with integer\ncharges, is well-known. However, our present work reveals a more intricate and\nnuanced physical perspective based on comprehensive first-principles/continuum\ncalculations. We investigate the dissolution and deposition processes of 22\nmetal elements across a range of applied electrode potentials, unveiling\ndiverse dissolution models. By analyzing the energy profiles and valence states\nof solute atoms as a function of the distance between the solute atom and metal\nsurface, we identify three distinct dissolution models for different metals.\nFirstly, solute atoms exhibit an integer valence state following an\ninteger-valence jump, aligning with classical understandings. Secondly, solute\natoms attain an eventual integer valence, yet their valence state increases in\na non-integer manner during dissolution. Lastly, we observe solute atoms\nexhibiting a non-integer valence state, challenging classical understandings.\nFurthermore, we propose a theoretical criterion for determining the selection\nof ion valence during electrode dissolution under applied potential. These\nfindings not only contribute to a deeper understanding of the dissolution\nprocess but also offer valuable insights into the complex dynamics governing\nmetal ion dissolution at the atomic level. Such knowledge has the potential to\nadvance the design of more efficient electrochemical systems and open new\navenues for controlling dissolution processes in various applications.",
        "positive": "Piezocaloric and multicaloric effect in the KH2PO4 type ferroelectrics: Using the proton ordering model modified by taking into account the\ndependence of the dipole moments on the order parameter [Vdovych et al, 2014],\nwe explore the piezocaloric and multicaloric effects in the KH$_{2}$PO$_{4}$\ntype ferroelectrics, caused by the shear stress $\\sigma_6$ and longitudinal\nelectric field $E_3$. The multicaloric effect is shown to be stronger than\neither electrocaloric or piezocaloric effects, especially at temperatures far\nfrom the phase transition."
    },
    {
        "anchor": "Coulomb scattering rates of excited states in germanene: The excited conduction electrons, conduction holes and valence holes in\nmonolayer germanene exhibit the feature-rich Coulomb decay rates. The\ndexcitation processes are studied using the Matsubara's screened exchange\nenergy. They might utilize the intraband single-particle excitations (SPEs),\nthe interband SPEs, and three kinds of plasmon modes, depending on the\nquasiparticle states and the Fermi energies. The low-lying valence holes can\ndecay by the undamped acoustic plasmon, so that they present very fast Coulomb\ndeexcitations, the non-monotonous energy dependence and the anisotropic\nbehavior. However, the low-energy conduction holes and electrons behave as 2D\nelectron gas. The high-energy conduction states and the deep-energy valence\nones are similar in the available deexcitation channels and the dependence of\ndecay rate on wave vector k.",
        "positive": "Spin correlated dielectric memory and rejuvenation in relaxor\n  ferroelectric CuCrS2: CuCrS2, a Heisenberg antiferromagnet with layered edge sharing triangular\nlattice, exhibits a spiral magnetic order. Dielectric (E) and polarization\nstudies show magnetoelectric (ME) coupling at Neel temperature (T_N=38 K) where\nsimultaneous dielectric and magnetic long range order occur. The compound shows\na diffused ferroelectric (FE) transition and slow relaxation dynamics above\nT_N, indicative of relaxor FE behavior. Interestingly, memory effect and\nmagnetic field induced rejuvenation are also observed in E, establishing\ncooperative glassy dynamics and ME coupling even above T_N. We discuss the role\nof geometrical frustration and metal ligand hybridization for these unusual\nproperties."
    },
    {
        "anchor": "Swift heavy ion irradiation of GaSb: from ion tracks to nano-porous\n  networks: Ion track formation, amorphisation, and the formation of porosity in\ncrystalline GaSb induced by 185 MeV $^{197}$Au swift heavy ion irradiation is\ninvestigated as a function of fluence and irradiation angle relative to the\nsurface normal. RBS/C and SAXS reveal an ion track radius between 3 nm and 5\nnm. The observed pore morphology and saturation swelling of GaSb films shows a\nstrong irradiation angle dependence. Raman spectroscopy and scanning electron\nmicroscopy show that the ion tracks act as a source of strain in the material\nleading to macroscopic plastic flow at high fluences and off normal\nirradiation. The results are consistent with the ion hammering model for\nglasses. Furthermore, wide angle X-ray scattering reveals the formation of nano\ncrystallites inside otherwise amorphous GaSb after the onset of porosity.",
        "positive": "Novel mechanism of photoinduced reversible phase transitions in\n  molecule-based magnets: A novel microscopic mechanism of bi-directional structural changes is\nproposed for the photo-induced magnetic phase transition in Co-Fe Prussian blue\nanalogues on the basis of ab initio quantum chemical cluster calculations. It\nis shown that the local potential energies of various spin states of Co are\nsensitive to the number of nearest neighbor Fe vacancies. As a result, the\nforward and backward structural changes are most readily initiated by\nexcitation of different local regions by different photons. This mechanism\nsuggests an effective strategy to realize photoinduced reversible phase\ntransitions in a general system consisting of two local components."
    },
    {
        "anchor": "Exceptionally Long-ranged Lattice Relaxation in Oxygen-deficient Ta2O5: The lattice relaxation in oxygen-deficient Ta2O5 is investigated using\nfirst-principles calculations. The presence of a charge-neutral oxygen vacancy\ncan result in a long-ranged lattice relaxation which extends beyond 18 {\\AA}\nfrom the vacancy site. The lattice relaxation has significant effects on the\nvacancy formation energy as well as the electronic structures. The long-ranged\nbehavior of the lattice relaxation is explained in terms of the\nHellmann-Feynman forces and the potential energy surface related to the\nvariation of Ta-O bond lengths.",
        "positive": "Electron self-energy and effective mass in a single heterostructure: In this paper, we investigate the electron self-energy and effective mass in\na single heterostructure using Green-function method. Numerical calculations of\nthe electron self-energy and effective mass for GaAs/AlAs heterostructure are\nperformed. The results show that the self energy (effective mass) of electron,\nwhich incorporate the energy of electron coupling to interface-optical phonons\nand half three-dimension LO phonons, monotonically increase(decrease) from that\nof interface polaron to that of 3D bulk polaron with the increase of the\ndistance between the position of the electron and interface."
    },
    {
        "anchor": "Interplay between ferromagnetism, surface states, and quantum\n  corrections in a magnetically doped topological insulator: The breaking of time-reversal symmetry by ferromagnetism is predicted to\nyield profound changes to the electronic surface states of a topological\ninsulator. Here, we report on a concerted set of structural, magnetic,\nelectrical and spectroscopic measurements of \\MBS thin films wherein\nphotoemission and x-ray magnetic circular dichroism studies have recently shown\nsurface ferromagnetism in the temperature range 15 K $\\leq T \\leq 100$ K,\naccompanied by a suppressed density of surface states at the Dirac point.\nSecondary ion mass spectroscopy and scanning tunneling microscopy reveal an\ninhomogeneous distribution of Mn atoms, with a tendency to segregate towards\nthe sample surface. Magnetometry and anisotropic magnetoresistance measurements\nare insensitive to the high temperature ferromagnetism seen in surface studies,\nrevealing instead a low temperature ferromagnetic phase at $T \\lesssim 5$ K.\nThe absence of both a magneto-optical Kerr effect and anomalous Hall effect\nsuggests that this low temperature ferromagnetism is unlikely to be a\nhomogeneous bulk phase but likely originates in nanoscale near-surface regions\nof the bulk where magnetic atoms segregate during sample growth. Although the\nsamples are not ideal, with both bulk and surface contributions to electron\ntransport, we measure a magnetoconductance whose behavior is qualitatively\nconsistent with predictions that the opening of a gap in the Dirac spectrum\ndrives quantum corrections to the conductance in topological insulators from\nthe symplectic to the orthogonal class.",
        "positive": "Interband infrared photodetectors based on HgTe--CdHgTe quantum-well\n  heterostructure: We calculate the characteristics of interband HgTe-CdHgTe quantum-well\ninfrared photodetectors (QWIPs). Due to a small probability of the electron\ncapture into the QWs, the interband HgTe-CdHgTe QWIPs can exhibit very high\nphotoconductive gain. Our analysis demonstrates significant potential\nadvantages of these devices compared to the conventional CdHgTe photodetectors\nand the A$_3$B$_5$ heterostructures."
    },
    {
        "anchor": "Electrostatic force microscopy and potentiometry of realistic\n  nanostructured systems: We investigate the dependency of electrostatic interaction forces on applied\npotentials in Electrostatic Force Microscopy (EFM) as well as in related local\npotentiometry techniques like Kelvin Probe Microscopy (KPM). The approximated\nexpression of electrostatic interaction between two conductors, usually\nemployed in EFM and KPM, may loose its validity when probe-sample distance is\nnot very small, as often realized when realistic nanostructured systems with\ncomplex topography are investigated. In such conditions, electrostatic\ninteraction does not depend solely on the potential difference between probe\nand sample, but instead it may depend on the bias applied to each conductor.\nFor instance, electrostatic force can change from repulsive to attractive for\ncertain ranges of applied potentials and probe-sample distances, and this fact\ncannot be accounted for by approximated models. We propose a general\ncapacitance model, even applicable to more than two conductors, considering\nvalues of potentials applied to each of the conductors to determine the\nresulting forces and force gradients, being able to account for the above\nphenomenon as well as to describe interactions at larger distances. Results\nfrom numerical simulations and experiments on metal stripe electrodes and\nsemiconductor nanowires supporting such scenario in typical regimes of EFM\ninvestigations are presented, evidencing the importance of a more rigorous\nmodelling for EFM data interpretation. Furthermore, physical meaning of Kelvin\npotential as used in KPM applications can also be clarified by means of the\nreported formalism.",
        "positive": "Controlling the 2DEG states evolution at a metal/Bi$_2$Se$_3$ interface: We have demonstrated that the evolution of the two-dimensional electron gas\n(2DEG) system at an interface of metal and the model topological insulator (TI)\nBi$_2$Se$_3$ can be controlled by choosing an appropriate kind of metal\nelements and by applying a low temperature evaporation procedure. In\nparticular, we have found that only topological surface states (TSSs) can exist\nat a Mn/Bi$_2$Se$_3$ interface, which would be useful for implementing an\nelectric contact with surface current channels only. The existence of the TSSs\nalone at the interface was confirmed by angle-resolved photoemission\nspectroscopy (ARPES). Based on the ARPES and core-level x-ray photoemission\nspectroscopy measurements, we propose a cation intercalation model to explain\nour findings."
    },
    {
        "anchor": "Local waiting time fluctuations along a randomly pinned crack front: The propagation of an interfacial crack along a heterogeneous weak plane of a\ntransparent Plexiglas block is followed using a high resolution fast camera. We\nshow that the fracture front dynamics is governed by local and irregular\navalanches with very large size and velocity fluctuations. We characterize the\nintermittent dynamics observed, i.e. the local pinnings and depinnings of the\ncrack front which trigger a rich burst activity, by measuring the local waiting\ntime fluctuations along the crack front during its propagation. The local front\nline velocity distribution deduced from the waiting time analysis exhibits a\npower law behavior, $P(v) \\propto v^{-\\eta}$ with $\\eta = 2.55 \\pm 0.15$, for\nvelocities $v$ larger than the average front speed $<v>$. The burst size\ndistribution is also a power law,\n  $P(S)\\propto S^{-\\gamma}$ with $\\gamma=1.7 \\pm 0.1$. Above a characteristic\nlength scale of disorder $L_d \\sim 15 \\mu m$, the avalanche clusters become\nanisotropic, and the scaling of the anisotropy ratio provides an estimate of\nthe roughness exponent of the crack front line, $H=0.66$, in close agreement\nwith previous independent estimates.",
        "positive": "On the electromagnetic force on a polarizable body: The force on a macroscopic polarizable body in an inhomogenous\nelectromagnetic field is calculated for three simple exactly solvable\nsituations. Comparing different approaches we pinpoint possible pitfalls and\nresolve recent confusion about the force density in ferrofluids."
    },
    {
        "anchor": "Size Effect in Fracture: Roughening of Crack Surfaces and Asymptotic\n  Analysis: Recently the scaling laws describing the roughness development of fracture\nsurfaces was proposed to be related to the macroscopic elastic energy released\nduring crack propagation [Mor00]. On this basis, an energy-based asymptotic\nanalysis allows to extend the link to the nominal strength of structures. We\nshow that a Family-Vicsek scaling leads to the classical size effect of linear\nelastic fracture mechanics. On the contrary, in the case of an anomalous\nscaling, there is a smooth transition from the case of no size effect, for\nsmall structure sizes, to a power law size effect which appears weaker than the\nlinear elastic fracture mechanics one, in the case of large sizes. This\nprediction is confirmed by fracture experiments on wood.",
        "positive": "Local Properties of the Potential Energy Landscape of a Model Glass:\n  Understanding the Low Temperature Anomalies: Though the existence of two-level systems (TLS) is widely accepted to explain\nlow temperature anomalies in the sound absorption, heat capacity, thermal\nconductivity and other quantities, an exact description of their microscopic\nnature is still lacking. We performed computer simulations for a binary\nLennard-Jones system, using a newly developed algorithm to locate double-well\npotentials (DWP) and thus two-level systems on a systematic basis. We show that\nthe intrinsic limitations of computer simulations like finite time and finite\nsize problems do not hamper this analysis. We discuss how the DWP are embedded\nin the total potential energy landscape. It turns out that most DWP are\nconnected to the dynamics of the smaller particles and that these DWP are\nrather localized. However, DWP related to the larger particles are more\ncollective."
    },
    {
        "anchor": "The Land\u00e9 factors of electrons and holes in lead halide perovskites:\n  universal dependence on the band gap: The Land\\'e or $g$-factors of charge carriers are decisive for the\nspin-dependent phenomena in solids and provide also information about the\nunderlying electronic band structure. We present a comprehensive set of\nexperimental data for values and anisotropies of the electron and hole Land\\'e\nfactors in hybrid organic-inorganic (MAPbI$_3$, MAPb(Br$_{0.5}$Cl$_{0.5}$)$_3$,\nMAPb(Br$_{0.05}$Cl$_{0.95}$)$_3$, FAPbBr$_3$,\nFA$_{0.9}$Cs$_{0.1}$PbI$_{2.8}$Br$_{0.2}$) and all-inorganic (CsPbBr$_3$) lead\nhalide perovskites, determined by pump-probe Kerr rotation and spin-flip Raman\nscattering in magnetic fields up to 10~T at cryogenic temperatures. Further, we\nuse first-principles DFT calculations in combination with tight-binding and\n$\\mathbf k \\cdot \\mathbf p$ approaches to calculate microscopically the Land\\'e\nfactors. The results demonstrate their universal dependence on the band gap\nenergy across the different perovskite material classes, which can be\nsummarized in a universal semi-phenomenological expression, in good agreement\nwith experiment.",
        "positive": "Compensation-dependent in-plane magnetization reversal processes in\n  Ga1-xMnxP1-ySy: We report the effect of dilute alloying of the anion sublattice with S on the\nin-plane uniaxial magnetic anisotropy and magnetization reversal process in\nGa1-xMnxP as measured by both ferromagnetic resonance (FMR) and superconducting\nquantum interference device (SQUID) magnetometry. At T=5K, raising the S\nconcentration increases the uniaxial magnetic anisotropy between in-plane <011>\ndirections while decreasing the magnitude of the (negative) cubic anisotropy\nfield. Simulation of the SQUID magnetometry indicates that the energy required\nfor the nucleation and growth of domain walls decreases with increasing y.\nThese combined effects have a marked influence on the shape of the\nfield-dependent magnetization curves; while the direction remains the easy axis\nin the plane of the film, the field dependence of the magnetization develops\ndouble hysteresis loops in the [011] direction as the S concentration increases\nsimilar to those observed for perpendicular magnetization reversal in lightly\ndoped Ga1-xMnxAs. The incidence of double hysteresis loops is explained with a\nsimple model whereby magnetization reversal occurs by a combination of coherent\nspin rotation and noncoherent spin switching, which is consistent with both FMR\nand magnetometry experiments. The evolution of magnetic properties with S\nconcentration is attributed to compensation of Mn acceptors by S donors, which\nresults in a lowering of the concentration of holes that mediate\nferromagnetism."
    },
    {
        "anchor": "Simulation of nanopowder high-speed compaction by 2d granular dynamics\n  method: The paper concerns the nanopowder high-speed, $10^4$ - $10^9$ s${}^{-1}$,\ncompaction processes modeling by a two-dimensional granular dynamics method.\nNanoparticles interaction, in addition to known contact laws, included\ndispersive attraction, formation of a strong interparticle bonding (powder\nagglomeration) as well as the forces caused by viscous stresses in the contact\nregion. For different densification rates, the \"pressure vs. density\" curves\n(densification curves) were calculated. Relaxation of the stresses after the\ncompression stage was analyzed as well. The densification curves analysis\nallowed us to suggest the dependence of compaction pressure as a function of\nstrain rate. It was found that in contrast to the plastic flow of metals, where\nthe yield strength is proportional to the logarithm of the strain rate, the\npower-law dependence of applied pressure on the strain rate as $p\\propto\nv^{1/4}$ was established for the modeled nanosized powders.",
        "positive": "Delocalization of dark and bright excitons in flat-band materials and\n  the optical properties of V$_2$O$_5$: The simplest picture of excitons in materials with atomic-like localization\nof electrons is that of Frenkel excitons, where electrons and holes stay close\ntogether, which is associated with a large binding energy. Here, using the\nexample of the layered oxide V$_2$O$_5$ , we show how localized charge-transfer\nexcitations combine to form excitons that also have a huge binding energy but,\nat the same time, a large electron-hole distance, and we explain this seemingly\ncontradictory finding. The anisotropy of the exciton delocalization is\ndetermined by the local anisotropy of the structure, whereas the exciton\nextends orthogonally to the chains formed by the crystal structure. Moreover,\nwe show that the bright exciton goes together with a dark exciton of even\nlarger binding energy and more pronounced anisotropy. These findings are\nobtained by combining first principles many-body perturbation theory\ncalculations, ellipsometry experiments, and tight binding modelling, leading to\nvery good agreement and a consistent picture. Our explanation is general and\ncan be extended to other materials."
    },
    {
        "anchor": "Dzyaloshinskii-Moriya Induced Spin-Transfer Torques in Kagome\n  Antiferromagnets: In recent years antiferromagnets (AFMs) have become very promising for\nnanoscale spintronic applications due to their unique properties such as THz\ndynamics and absence of stray fields. Manipulating antiferromagnetic textures\nis currently, however, limited to very few exceptional material symmetry\nclasses allowing for staggered torques on the magnetic sublattices. In this\nwork, we predict for kagome AFMs with broken mirror symmetry a new coupling\nmechanism between antiferromagnetic domain walls (DWs) and spin currents,\nproduced by the relativistic Dzyaloshinskii-Moriya interaction (DMI). We\nmicroscopically derive the DMI's free energy contribution for the kagome AFMs.\nUnlike ferromagnets and collinear AFMs, the DMI does not lead to terms linear\nin the spatial derivatives but instead renormalizes the spin-wave stiffness and\nanisotropy energies. Importantly, we show that the DMI induces a highly\nnontrivial twisted DW profile that is controllable via two linearly independent\ncomponents of the spin accumulation. This texture manipulation mechanism goes\nbeyond the concept of staggered torques and implies a higher degree of\ntunability for the current-driven DW motion compared to conventional\nferromagnets and collinear AFMs.",
        "positive": "Emergent Phenomena with Broken Parity-Time Symmetry: Odd-order vs.\n  Even-order Effects: Symmetry often governs the laws of nature, and breaking symmetry accompanies\na new order parameter and emergent observable phenomena. Herein, we focus on\nbroken Parity (P)-Time (T) symmetry, which lifts the Kramers' degeneracy, and\nthus, guarantees non-trivial spin textures in excitation spectra. To attain\nnon-zero measurables, we use the concept of symmetry operational similarity\n(SOS), which consider the symmetry relationship between a specimen and an\nexperimental setup, rather than the symmetry of specific coupling terms. Even\nwithout specific coupling terms, this SOS approach can tell if the relevant\nphenomenon is a zero, non-zero odd-order or non-zero even-order effect. We\ndiscuss systematically numerous steady-state physical phenomena, in which\nbreaking P-T symmetry is a necessary condition. These phenomena include\nOdd-order or Even-order Anomalous Hall Effect, Optical activities, Directional\nnonreciprocity in transverse magnetic field, Diagonal or Off-diagonal\ncurrent-induced magnetization (current can be associated with electrons,\nphonons, or light), Diagonal or Off-diagonal piezomagnetism and\npiezoelectricity. Some of these phenomena turn out to be conjugate to each\nother through P to T. Our findings unveil numerous new non-traditional\ncandidate materials for various exotic physical phenomena, many of which have\nnever been realized in the standard coupling term/tensorial approaches, and are\na transformative and unconventional avenue for symmetry-guided materials\ndesigns and discoveries."
    },
    {
        "anchor": "Nearly ideal memristive functionality based on viscous magnetization\n  dynamics: We experimentally demonstrate a proof-of-principle implementation of an\nalmost ideal memristor - a two-terminal circuit element whose resistance is\napproximately proportional to the integral of the input signal over time. The\ndemonstrated device is based on a thin-film ferromagnet/antiferromagnet\nbilayer, where magnetic frustration results in viscous magnetization dynamics\nenabling memristive functionality, while the external magnetic field plays the\nrole of the driving input. The demonstrated memristor concept is amenable to\ndownscaling and can be adapted for electronic driving, making it attractive for\napplications in neuromorphic circuits.",
        "positive": "Adsorption geometry and the interface states: The relaxed and compressed\n  phases of NTCDA/Ag(111): The theoretical modelling of metal-organic interfaces represents a formidable\nchallenge, especially in consideration of the delicate balance of various\ninteraction mechanisms and the large size of involved molecular species. In the\npresent study, the energies of interface states, which are known to display a\nhigh sensitivity to the adsorption geometry and electronic structure of the\ndeposited molecular species, have been used to test the suitability and\nreliability of current theoretical approaches. Two well-ordered overlayer\nstructures (relaxed and compressed monolayer) of NTCDA on Ag(111) have been\ninvestigated using two-photon-photoemission to derive precise interface state\nenergies for these closely related systems. The experimental values are\nreproduced by our DFT calculations using different treatments of dispersion\ninteractions (optB88, PBE-D3) and basis set approaches (localized numerical\natomic orbitals, plane waves) with remarkable accuracy. This underlines the\ntrustworthiness regarding the description of geometric and electronic\nproperties."
    },
    {
        "anchor": "Interfacial giant tunnel magnetoresistance and bulk-induced large\n  perpendicular magnetic anisotropy in (111)-oriented junctions with fcc\n  ferromagnetic alloys: A first-principles study: We study the tunnel magnetoresistance (TMR) effect and magnetocrystalline\nanisotropy in a series of magnetic tunnel junctions (MTJs) with $L1_1$-ordered\nfcc ferromagnetic alloys and MgO barrier along the [111] direction. Considering\nthe (111)-oriented MTJs with different $L1_1$ alloys, we calculate their TMR\nratios and magnetocrystalline anisotropies on the basis of the first-principles\ncalculations. The analysis shows that the MTJs with Co-based alloys (CoNi,\nCoPt, and CoPd) have high TMR ratios over 2000$\\%$. These MTJs have\nenergetically favored Co-O interfaces where interfacial antibonding between Co\n$d$ and O $p$ states is formed around the Fermi level. We find that the\nresonant tunneling of the antibonding states, called the interface resonant\ntunneling, is the origin of the obtained high TMR ratios. Our calculation of\nthe magnetocrystalline anisotropy shows that many $L1_1$ alloys have large\nperpendicular magnetic anisotropy (PMA). In particular, CoPt has the largest\nvalue of anisotropy energy $K_{\\rm u} \\approx 10\\,{\\rm MJ/m^3}$. We further\nconduct a perturbation analysis of the PMA with respect to the spin-orbit\ninteraction and reveal that the large PMA in CoPt and CoNi mainly originates\nfrom spin-conserving perturbation processes around the Fermi level.",
        "positive": "Large spin Hall effect in 5d-transition metal anti-perovskites: The spin Hall effect (SHE) is highly promising for spintronic applications,\nand the design of materials with large SHE can enable ultra-low power memory\ntechnology. Recently, 5d-transition metal oxides have been shown to demonstrate\na large SHE. Here we report large values of SHE in four 5d-transition metal\nanti-perovskites which makes these anti-perovskites promising spintronic\nmaterials. We demonstrate that these effects originate in the mixing of dx2-y2\nand dxy orbitals caused by spin orbit coupling."
    },
    {
        "anchor": "Extraordinary stiffness tunability through thermal expansion of\n  nonlinear defect modes: Incremental stiffness characterizes the variation of a material's force\nresponse to a small deformation change. Typically materials have an incremental\nstiffness that is fixed and positive, but recent technologies, such as\nsuper-lenses, low frequency band gap materials and acoustic cloaks, are based\non materials with zero, negative or extremely high incremental stiffness. So\nfar, demonstrations of this behavior have been limited either to a narrow range\nof frequencies, temperatures, stiffness or to specific deformations. Here we\ndemonstrate a mechanism to tune the static incremental stiffness that overcomes\nthose limitations. This tunability is achieved by driving a nonlinear defect\nmode in a lattice. As in thermal expansion, the defect's vibration amplitude\naffects the force at the boundary, hence the lattice's stiffness. By using the\nhigh sensitivities of nonlinear systems near bifurcation points, we tune the\nmagnitude of the incremental stiffness over a wide range: from positive, to\nzero, to arbitrarily negative values. The particular deformation where the\nincremental stiffness is modified can be arbitrarily selected varying the\ndefect's driving frequency. We demonstrate this experimentally in a compressed\narray of spheres and propose a general theoretical model.",
        "positive": "One-Dimensional Spin-Polarised Surface States -- A Comparison of Bi(112)\n  with Other Vicinal Bismuth Surfaces: Vicinal surfaces of bismuth are unique test-beds for investigating\none-dimensional (1D) spin-polarised surface states that may one day be used in\nspintronic devices. In this work, two such states have been observed for the\n(112) surface when measured using angle-resolved photoemission spectroscopy\n(ARPES) and spin-resolved ARPES, and when calculated using a tight-binding (TB)\nmodel and with density functional theory (DFT). The surface states appear as\nelongated Dirac-cones which are 1D and almost dispersionless in the\n${k}_{\\text{y}}$-direction, but disperse with energy in the orthogonal\n${k}_{\\text{x}}$-direction to form two ``$\\times$''-like features centered at\nthe ${k}_{\\text{y}}$-line through ${\\Gamma}$. Unlike many materials considered\nfor spintronic applications, their 1D nature suggests that conductivity and\nspin-transport properties are highly dependent on direction. The\nspin-polarisation of the surface states is mainly in-plane and parallel to the\n1D state, but there are signs of a tilted out-of-plane spin-component for one\nof them. The Bi(112) surface states resemble those found for other vicinal\nsurfaces of bismuth, strongly indicating that their existence and general\nproperties are robust properties of vicinal surfaces of bismuth. Furthermore,\ndifferences in the details of the states, particularly related to their\nspin-polarisation, suggest that spin-transport properties may be engineered\nsimply by precise cutting and polishing of the crystal."
    },
    {
        "anchor": "Unexpected properties of the first excited state of non-bipartite\n  Heisenberg spin rings: Systematic properties of the first excited state are presented for various\nring sizes and spin quantum numbers which are only partly covered by the\ntheorem of Lieb, Schultz and Mattis. For odd ring sizes the first excited\nenergy eigenvalue shows unexpected degeneracy and related shift quantum\nnumbers. As a byproduct the ground state energy as well as the energy of the\nfirst excited state of infinite chains are calculated by extrapolating the\nproperties of only a few, finite, antiferromagnetically coupled Heisenberg\nrings using the powerful Levin sequence acceleration method.",
        "positive": "Electrons in helical magnetic field: a new class of topological metals: Two theorems on electron states in helimagnets are proved. They reveal a\nKramers-like degeneracy in helical magnetic field. Since a commensurate helical\nmagnetic system is transitionally invariant with two multiple periods (ordinary\ntranslations and generalized ones with rotations), the band structure turns out\nto be topologically nontrivial. Together with the degeneracy, this gives an\nunusual spin structure of electron bands. A 2D model of nearly free electrons\nis proposed to describe conductive hexagonal palladium layers under an\neffective field of magnetically ordered CrO$_2$ spacers in PdCrO$_2$. The spin\ntexture of the Fermi surface leads to abnormal conductivity."
    },
    {
        "anchor": "Equilibrium and out-of-equilibrium over-screening free phonon\n  self-energy in realistic materials: In model Hamiltonians, like Fr\\\"ohlich's, the electron-phonon interaction is\nassumed to be screened from the beginning. The same occurs when this\ninteraction is obtained by using the state-of-the-art density functional\nperturbation theory as starting point. In this work I formally demonstrate that\nthese approaches are affected by a severe over-screening error. By using an\nout-of-equilibrium Many-Body technique I discuss how to merge the many-body\napproach with density-functional perturbation theory in order to correct the\nover-screening error. A symmetric statically screened phonon self-energy is\nobtained by down-folding the exact Baym-Kadanoff equations. The statically\nscreened approximation proposed here is shown to have the same long-range\nspatial limit of the exact self-energy and to respect the\nfluctuation-dissipation theorem. The doubly screened approximation, commonly\nused in the literature, is shown, instead, to be over-screened, to violate\nseveral Many-Body properties and to have a wrong spatial long-range decay. The\naccuracy of the proposed approximation is tested against the exact solution of\nan extended model Fr\\\"ohlich Hamiltonian and it is applied to a paradigmatic\nmaterial: MgB$_2$. I find that the present treatment enhances the linewidths by\n$57 \\%$ with respect to what has been previously reported for the anomalous\n$E_{2g}$ mode. I further discover that the $A_{2u}$ mode is also anomalous (its\nstrong coupling being completely quenched by the over-screened expression). The\npresent results deeply question methods based on state-of-the-art approaches\nand impact a wide range of fields such as thermal conductivity, phononic\ninstabilities and non-equilibrium lattice dynamics.",
        "positive": "Reexamination of the Elliott-Yafet spin-relaxation mechanism: We analyze spin-dependent carrier dynamics due to incoherent electron-phonon\nscattering, which is commonly referred to as Elliott-Yafet (EY) spin-relaxation\nmechanism. For this mechanism one usually distinguishes two contributions: (1)\nfrom the electrostatic interaction together with spin-mixing in the wave\nfunctions, which is often called the Elliott contribution, and (2) the\nphonon-modulated spin-orbit interaction, which is often called the Yafet or\nOverhauser contribution. By computing the reduced electronic density matrix, we\nimprove Yafet's original calculation, which is not valid for pronounced spin\nmixing as it equates the pseudo-spin polarization with the spin polarization.\nThe important novel quantity in our calculation is a torque operator that\ndetermines the spin dynamics. The contribution (1) to this torque vanishes\nexactly. From this general result, we derive a modified expression for the\nElliott-Yafet spin relaxation time."
    },
    {
        "anchor": "Ballistic versus diffusive magnetoresistance of a magnetic point contact: The quasiclassical theory of a nanosize point contacts (PC) between two\nferromagnets is developed. The maximum available magnetoresistance values in PC\nare calculated for ballistic versus diffusive transport through the area of a\ncontact. In the ballistic regime the magnetoresistance in excess of few\nhundreds percents is obtained for the iron-group ferromagnets. The necessary\nconditions for realization of so large magnetoresistance in PC, and the\nexperimental results by Garcia et al are discussed",
        "positive": "First principles investigation of magnetocrystalline anisotropy at the\n  L2$_1$ Full Heusler|MgO interfaces and tunnel junctions: Magnetocrystalline anisotropy at Heusler alloy$|$MgO interfaces have been\nstudied using first principles calculations. It is found that Co terminated\nCo$_{2}$FeAl$|$MgO interfaces show perpendicular magnetic anisotropy up to 1.31\nmJ/m$^2$, while those with FeAl termination exhibit in-plane magnetic\nanisotropy. Atomic layer resolved analysis indicates that the origin of\nperpendicular magnetic anisotropy in Co$_{2}$FeAl$|$MgO interfaces can be\nattributed to the out-of-plane orbital contributions of interfacial Co atoms.\nAt the same time, Co$_{2}$MnGe and Co$_{2}$MnSi interfaced with MgO tend to\nfavor in-plane magnetic anisotropy for all terminations."
    },
    {
        "anchor": "Laser-induced Translative Hydrodynamic Mass Snapshots: mapping at\n  nanoscale: Nanoscale thermally assisted hydrodynamic melt perturbations induced by\nultrafast laser energy deposition in noble-metal films produce irreversible\nnanoscale translative mass redistributions and results in formation of\nradially-symmetric frozen surface structures. We demonstrate that the final\nthree-dimensional (3D) shape of the surface structures formed after\nresolidification of the molten part of the film is shown to be governed by\nincident laser fluence and, more importantly, predicted theoretically via\nmolecular dynamics modeling. Considering the underlying physical processes\nassociated with laser-induced energy absorption, electron-ion energy exchange,\nacoustic relaxation and hydrodynamic flows, the theoretical approach separating\nslow and fast physical processes and combining hybrid analytical\ntwo-temperature calculations, scalable molecular-dynamics simulations, and a\nsemi-analytical thin-shell model was shown to provide accurate prediction of\nthe final nanoscale solidified morphologies, fully consistent with direct\nelectron-microscopy visualization of nanoscale focused ion-beam cuts of the\nsurface structures produced at different incident laser fluences. Finally,\nthese results are in reasonable quantitative agreement with mass distribution\nprofiles across the surface nanostructures, provided by their noninvasive and\nnon-destructive nanoscale characterization based on energy-dispersive x-ray\nfluorescence spectroscopy, operating at variable electron-beam energies.",
        "positive": "AgBiSe2 Colloidal Nanocrystals for Use in Solar Cells: Metal selenide nanocrystals have attracted attention as promising materials\nin photovoltaics and thermoelectrics. However, the expensive and\nlabor-intensive synthesis methods utilized for the production of these\nnanomaterials have impeded their widespread utilization. The need for air-free\nenvironment and high synthesis temperature for crystal nucleation and growth\nlead as the major factors contributing to the cost of synthesis. In this work,\nwe present a synthesis method for metal selenide nanocrystals at room\ntemperature under ambient conditions that is enabled by a cost-effective\nselenium precursor."
    },
    {
        "anchor": "X-ray absorption and resonant inelastic x-ray scattering in the rare\n  earths: This paper makes a comparison between x-ray absorption (XAS) and resonant\ninelastic x-ray scattering (RIXS) in the rare earths. Atomic calculations are\ngiven for 2p -> 4f and 2p -> 5d XAS. The latter calculation includes the\ncontraction and expansion of the 5d orbitals resulting from the complete\nexchange interaction with the 4f electrons. The radiative decay of the XAS\nfinal states is described for the situations where the core hole created in the\nabsorption process is filled by a valence electron or by an electron from a\nshallower core level. RIXS spectra, 4f^n -> _{3d} 4f^{n+1} -> 4f^n,integrated\nover the outgoing photon energy (fluorescence yield) are compared with 3d -> 4f\nXAS. Sum rules related to XAS and RIXS and their applicability are discussed.",
        "positive": "Phase Classification of Multi-Principal Element Alloys via Interpretable\n  Machine Learning: There is intense interest in uncovering design rules that govern the\nformation of various structural phases as a function of chemical composition in\nmulti-principal element alloys (MPEAs). In this paper, we develop a machine\nlearning (ML) approach built on the foundations of ensemble learning, post hoc\nmodel interpretability of black-box models and clustering analysis to establish\na quantitative relationship between the chemical composition and experimentally\nobserved phases of MPEAs. The novelty of our work stems from performing\ninstance-level (or local) variable attribution analysis of ML predictions based\non the breakdown method, and then identifying similar instances based on\nk-means clustering analysis of the breakdown results. We also complement the\nbreakdown analysis with Ceteris Paribus profiles that showcase how the model\nresponse changes as a function of a single variable, when the values of all\nother variables are fixed. Results from local model interpretability analysis\nuncover key insights into variables that govern the formation of each phase.\nOur developed approach is generic, model-agnostic, and valuable to explain the\ninsights learned by the black-box models. An interactive web application is\ndeveloped to facilitate model sharing and accelerate the design of novel MPEAs\nwith targeted properties"
    },
    {
        "anchor": "Competing periodicities in fractionally filled one-dimensional bands: We present a variable temperature Scanning Tunneling Microscopy and\nSpectroscopy (STM and STS) study of the Si(553)-Au atomic chain reconstruction.\nThis quasi one-dimensional (1D) system undergoes at least two charge density\nwave (CDW) transitions at low temperature, which can be attributed to\nelectronic instabilities in the fractionally-filled 1D bands of the\nhigh-symmetry phase. Upon cooling, Si(553)-Au first undergoes a single-band\nPeierls distortion, resulting in period doubling along the imaged chains. This\nPeierls state is ultimately overcome by a competing tripleperiod CDW, which in\nturn is accompanied by a x2 periodicity in between the chains. These locked-in\nperiodicities indicate small charge transfer between the nearly half-filled and\nquarter-filled 1D bands. The presence and the mobility of atomic scale\ndislocations in the x3 CDW state indicates the possibility of manipulating\nphase solitons carrying a (spin,charge) of (1/2,+-e/3) or (0,+-2e/3).",
        "positive": "Ferromagnetism and impurity band in a new magnetic semiconductor: InMnP: We have synthesized ferromagnetic InMnP, a member of III-Mn-V ferromagnetic\nsemiconductor family, by Mn ion implantation and pulsed laser annealing. Clear\nferromagnetic hysteresis loops and a perpendicular magnetic anisotropy are\nobserved up to a Curie temperature of 42 K. Large values of negative\nmagnetoresistance and magnetic circular dichroism as well as anomalous Hall\neffect are further evidences of a ferromagnetic order in InMnP. An effort is\nmade to understand the transport mechanism in InMnP using the theoretical\nmodels. We find that the valence band of InP does not merge with the impurity\nband of the heavily doped ferromagnetic InMnP. Our results suggest that\nimpurity band conduction is a characteristic of Mn-doped III-V semiconductors\nwhich have deep Mn-acceptor levels."
    },
    {
        "anchor": "Stabilizing Single Ni adatoms on a Two-dimensional Porous Titania\n  Overlayer at the SrTiO$_3$(110) Surface: Nickel vapor-deposited on the SrTiO$_3$(110) surface was studied using\nscanning tunneling microscopy, photoemission spectroscopy (PES), and density\nfunctional theory calculations. This surface forms a (4 $\\times$ 1)\nreconstruction, composed of a 2-D titania structure with periodic six- and\nten-membered nanopores. Anchored at these nanopores, Ni single adatoms are\nstabilized at room temperature. PES measurements show that the Ni adatoms\ncreate an in-gap state located at 1.9 eV below the conduction band minimum and\ninduce an upward band bending. Both experimental and theoretical results\nsuggest that Ni adatoms are positively charged. Our study produces\nwell-dispersed single-adatom arrays on a well-characterized oxide support,\nproviding a model system to investigate single-adatom catalytic and magnetic\nproperties.",
        "positive": "Phase transitions and molecular dynamics of n-hexadecanol confined in\n  silicon nanochannels: We present a combined x-ray diffraction and infrared spectroscopy study on\nthe phase behavior and molecular dynamics of n-hexadecanol in its bulk state\nand confined in an array of aligned nanochannels of 8 nm diameter in mesoporous\nsilicon. Under confinement the transition temperatures between the liquid, the\nrotator RII and the crystalline C phase are lowered by approximately 20K. While\nbulk n-hexadecanol exhibits at low temperatures a polycrystalline mixture of\northorhombic beta- and monoclinic gamma-forms, geometrical confinement favors\nthe more simple beta-form: only crystallites are formed, where the chain axis\nare parallel to the layer normal. However, the gamma-form, in which the chain\naxis are tilted with respect to the layer normal, is entirely suppressed. The\nbeta-crystallites form bi-layers, that are not randomly orientated in the\npores. The molecules are arranged with their long axis perpendicular to the\nlong channel axis. With regard to the molecular dynamics, we were able to show\nthat confinement does not affect the inner-molecular dynamics of the CH_2\nscissor vibration and to evaluate the inter-molecular force constants in the C\nphase."
    },
    {
        "anchor": "Higher-order Topological Point State: Higher-order topological insulators (HOTIs) have attracted increasing\ninterest as a unique class of topological quantum materials. One distinct\nproperty of HOTIs is the crystalline symmetry-imposed topological state at the\nlower-dimensional outer boundary, e.g. the zero-dimensional (0D) corner state\nof a 2D HOTI, used exclusively as a universal signature to identify\nhigher-order topology but yet with uncertainty. Strikingly, we discover the\nexistence of inner topological point states (TPS) in a 2D HOTI, as the embedded\n\"end\" states of 1D first-order TI, as exemplified by those located at the\nvacancies in a Kekule lattice. Significantly, we demonstrate that such inner\nTPS can be unambiguously distinguished from the trivial point-defect states, by\ntheir unique topology-endowed inter-TPS interaction and correlated magnetic\nresponse in spectroscopy measurements, overcoming an outstanding experimental\nchallenge. Furthermore, based on first-principles calculations, we propose\n{\\gamma}-graphyne as a promising material to observe the higher-order TPS. Our\nfindings shed new light on our fundamental understanding of HOTIs, and also\nopen an avenue to experimentally distinguishing and tuning TPS in the interior\nof a 2D sample for potential applications.",
        "positive": "Thermal-radiation-induced nonequilibrium carriers in an intrinsic\n  graphene: We examine an intrinsic graphene connected to the phonon thermostat at\ntemperature T under irradiation of thermal photons with temperature T_r, other\nthan T. The distribution of nonequilibrium electron-hole pairs was obtained for\nthe cases of low and high concentration of carriers. For the case when the\ninterparticle scattering is unessential, the distribution function is\ndetermined by the interplay of intraband relaxation of energy due to acoustic\nphonons and interband radiative transitions caused by the thermal radiation.\nWhen the Coulomb scattering dominates, then the quasi-equilibrium distribution\nwith effective temperature and non-equilibrium concentration, determined\nthrough balance equations, is realized. Due to the effect of thermal radiation\nwith temperature $T_r\\neq T$ concentration and conductivity of carriers in\ngraphene modify essentially. It is demonstrated, that at $T_r>T$ the negative\ninterband absorption, caused by the inversion of carriers distribution, can\noccur, i.e. graphene can be unstable under thermal irradiation."
    },
    {
        "anchor": "Alloy engineering of topological semimetal phase transition in\n  MgTa$_{2-x}$Nb$_x$N$_3$: Dirac, triple-point and Weyl fermions represent three topological semimetal\nphases, characterized with a descending degree of band degeneracy, which have\nbeen realized separately in specific crystalline materials with different\nlattice symmetries. Here we demonstrate an alloy engineering approach to\nrealize all three types of fermions in one single material system of\nMgTa$_{2-x}$Nb$_x$N$_3$. Based on symmetry analysis and first-principles\ncalculations, we map out a phase diagram of topological order in the parameter\nspace of alloy concentration and crystalline symmetry, where the intrinsic\nMgTa$_2$N$_3$ with the highest symmetry hosts the Dirac semimetal phase which\ntransforms into the triple-point and then the Weyl semimetal phase with the\nincreasing Nb concentration that lowers the crystalline symmetries. Therefore,\nalloy engineering affords a unique approach for experimental investigation of\ntopological transitions of semimetallic phases manifesting different fermionic\nbehaviors.",
        "positive": "A modified divide-and-conquer based machine learning method for\n  predicting creep life of superalloys: Recently Liu et al. (Acta Mater., 2020) proposed a new divide-and-conquer\nbased machine learning method for predicting creep life of superalloys. The\nidea is enlightening though, the prediction accuracy and intelligence remain to\nbe improved. In the present work, we modify the method by adding a\ndimensionality reduction algorithm before the clustering step and introducing a\ngrid search algorithm to the regression model selection step. As a consequence,\nthe clustering result becomes much more desirable and the accuracy of predicted\ncreep life is dramatically improved. The root-mean-square error,\nmean-absolute-percentage error and relevant coefficient of the original method\nare 0.2341, 0.0595 and 0.9121, while those of the modified method are 0.0285,\n0.0196, and 0.9806, respectively. Moreover, the ad-hoc determination of\nhyperparameters in the original method is replaced by automated determination\nof hyperparameters in the modified method, which considerably improves the\nintelligence of the method."
    },
    {
        "anchor": "Accurate evaluation of the fractal dimension based on a single\n  morphological image: Fractal dimension (D) is an effective parameter to represent the irregularity\nand fragmental property of a self-affine surface, which is common in physical\nvapor deposited thin films. D could be evaluated through the scaling\nperformance of surface roughness by using atomic force microscopy (AFM)\nmeasurements, but lots of AFM images with different scales (L) are needed. In\nthis study, a surface roughness prediction (SRP) method was proposed to\nevaluate D values of a single AFM image, in which the roughness at smaller L\nwas estimated by image segmentation with flatten modification. Firstly, a\nseries of artificial fractal surfaces with ideal dimension (Di) values ranging\nfrom 2.1 to 2.9 were generated through Weierstrass-Mandelbrot (W-M) function,\nin order to compare SRP method with traditional methods such as box counting\nmethod and power spectral density method. The calculated dimension (Dc) by SRP\nmethod was much closer to Di than the other methods, with a mean relative error\nof only 0.64%. Secondly, SRP method was utilized to deal with real surfaces,\nwhich were AFM images of amorphous alumina thin films with L of 1-70 {\\mu}m. Dc\nobtained by SRP method based on a single AFM image was also close to the result\nin our previous study by multi-image analysis at L above 10 {\\mu}m, while the\nlarger Dc at smaller L was consisted with the actual surface feature. The\nvalidity of SRP method and the physics nature of real surfaces were discussed,\nwhich might be helpful to obtain more understandings of fractal geometry.",
        "positive": "Controlled Transition Metal Nucleated Growth of Carbon Nanotubes by\n  Molten Electrolysis of CO$_2$: The electrolysis of CO$_2$ in molten carbonate has been introduced as an\nalternative mechanism to synthesize carbon nanomaterials inexpensively at high\nyield. Until recently, CO$_2$ was thought to be unreactive, making its removal\na challenge. CO$_2$ is the main cause of anthropogenic global warming and its\nutilization and transformation into a stable, valuable material provides an\nincentivized pathway to mitigate climate change. This study focuses on\ncontrolled electrochemical conditions in molten lithium carbonate to split\nCO$_2$ absorbed from the atmosphere into into carbon nanotubes, and into\nvarious macroscopic assemblies of CNTs,, which may be useful for\nnano-filtration. Different CNTs, morphologies were prepared electrochemically\nby variation of the anode and cathode composition and architecture, electrolyte\ncomposition pre-electrolysis processing, and the variation of current\napplication and current density. Individual CNT morphologies structures and the\nCNT molten carbonate growth mechanism are explored by SEM, TEM, HAADF EDX, XRD\nand Raman. The principle commercial technology for CNT production had been\nchemical vapor deposition, which is an order of magnitude more expensive,\ngenerally requires metallo-organics, rather than CO$_2$ as reactants, and can\nbe highly energy and CO$_2$ emission intensive (carries a high carbon positive,\nrather than negative, footprint)."
    },
    {
        "anchor": "H$_{2}$-diluted precursors for GaAs doping in chemical beam epitaxy: A wide range of n- and p-type doping levels in GaAs layers grown by chemical\nbeam epitaxy is achieved using H$_{2}$-diluted DTBSi and CBr$_{4}$ as gas\nprecursors for Si and C. We show that the doping level can be varied by\nmodifying either the concentration or the flux of the diluted precursor.\nSpecifically, we demonstrate carrier concentrations of\n6$\\times$10$^{17}$-1.2$\\times$10$^{19}$ cm$^{-3}$ for Si, and\n9$\\times$10$^{16}$-3.7$\\times$10$^{20}$ cm$^{-3}$ for C, as determined by Hall\neffect measurements. The incorporation of Si and C as a function of the flux of\nthe corresponding diluted precursor is found to follow, respectively, a first\nand a fourth order power law. The dependence of the electron and hole mobility\nvalues on the carrier concentration as well as the analysis of the layers by\nlow-temperature (12 K) photoluminescence spectroscopy indicate that the use of\nH$_{2}$ for diluting DTBSi or CBr$_{4}$ has no effect on the electrical and\noptical properties of GaAs.",
        "positive": "Observation of Bloch-point domain walls in cylindrical magnetic\n  nanowires: Topological protection is an elegant way of warranting the integrity of\nquantum and nanosized systems. In magnetism one example is the Bloch-point, a\npeculiar object implying the local vanishing of magnetization within a\nferromagnet. Its existence had been postulated and described theoretically\nsince several decades, however it has never been observed. We con rm\nexperimentally the existence of Bloch points, imaged within domain walls in\ncylindrical magnetic nanowires, combining surface and transmission XMCD-PEEM\nmagnetic microscopy. This opens the way to the experimental search for peculiar\nphenomena predicted during the motion of Bloch-point-based domain walls."
    },
    {
        "anchor": "Tunable photochemical deposition of silver nanostructures on layered\n  ferroelectric CuInP$_2$S6: 2D layered ferroelectric materials such as CuInP$_2$S6 (CIPS) are promising\ncandidates for novel and high-performance photocatalysts, owning to their\nultrathin layer thickness, strong interlayer coupling, and intrinsic\nspontaneous polarization, while how to control the photocatalytic activity in\nlayered CIPS remains unexplored. In this work, we report for the first time the\nphotocatalytic activity of ferroelectric CIPS for the chemical deposition of\nsilver nanostructures (AgNSs). The results show that the shape and spatial\ndistribution of AgNSs on CIPS are tunable by controlling layer thickness,\nenvironmental temperature, and light wavelength. The ferroelectric polarization\nin CIPS plays a critical role in tunable AgNS photodeposition, as evidenced by\nlayer thickness and temperature dependence experiments. We further reveal that\nAgNS photodeposition process starts from the active site creation, selective\nnanoparticle nucleation/aggregation, to the continuous film formation.\nMoreover, AgNS/CIPS heterostructures prepared by photodeposition exhibit\nexcellent resistance switching behavior and good surface enhancement Raman\nScattering activity. Our findings provide new insight into the photocatalytic\nactivity of layered ferroelectrics and offer a new material platform for\nadvanced functional device applications in smart memristors and enhanced\nchemical sensors.",
        "positive": "Synthesis, Characterization, and Magnetic Properties of gamma-NaxCoO2\n  (0.70 < x <0.84): Powder Na$_{x}$CoO$_{2}$ ($0.70\\leq x\\leq 0.84$) samples were synthesized and\ncharacterized carefully by X-ray diffraction analysis, inductive-coupled plasma\natomic emission spectroscopy, and redox titration. It was proved that\n$\\gamma$-Na$_{x}$CoO$_{2}$ is formed only in the narrow range of $0.70\\leq\nx\\leq 0.78$. Nevertheless, the magnetic properties depend strongly on $x$. We\nfound, for the first time, two characteristic features in the magnetic\nsusceptibility of Na$_{0.78}$CoO$_{2}$, a sharp peak at $T_{p}=16$ K and an\nanomaly at $T_{k}=9$ K, as well as the transition at $T_{c}=22$ K and the broad\nmaximum at $T_{m}=50$ K which had already been reported. A type of weak\nferromagnetic transition seems to occur at $T_{k}$. The transition at $T_{c}$,\nwhich is believed to be caused by spin density wave formation, was observed\nclearly for $x\\geq 0.74$ with constant $T_{c}$ and $T_{p}$ independent of $x$.\nOn the other hand, ferromagnetic moment varies systematically depending on $x$.\nThese facts suggest the occurrence of a phase separation at the microscopic\nlevel, such as the separation into Na-rich and Na-poor domains due to the\nsegregation of Na ions. The magnetic phase diagram and transition mechanism\nproposed previously should be reconsidered."
    },
    {
        "anchor": "Vortex state oscillations in soft magnetic cylindrical dots: We have studied magnetic vortex oscillations in soft sub-micron cylindrical\ndots with variable thickness and diameter by an analytical approach and\nmicromagnetic simulations. We have considered two kinds of modes of the vortex\nmagnetization oscillations: 1) low-frequency translation mode, corresponding to\nthe movement of the vortex as a whole near its equilibrium position; 2)\nhigh-frequency vortex modes, which correspond to radially symmetric\noscillations of the vortex magnetization, mainly outside the vortex core. The\nvortex translational eigenmode was calculated numerically in frequency and time\ndomains for different dot aspect ratios. To describe the discrete set of vortex\nhigh-frequency modes we applied the linearized equation of motion of dynamic\nmagnetization over the vortex ground state. We considered only radially\nsymmetric magnetization oscillations modes. The eigenfrequencies of both kinds\nof excitation modes are determined by magnetostatic interactions. They are\nproportional to the thickness/diameter ratio and lie in the GHz range for\ntypical dot sizes.",
        "positive": "Effect of copper content on thermal and mechanical properties of\n  eutectoid zn-al alloy: Zn-Al alloys have become one of the major engineering alloys among\ncommercially available alloys. This study was conducted on eutectoid\ncomposition of Zn-Al alloy with an observation of the effect of copper\naddition. For this purpose, one eutectoid (Zn-22wt%Al) and three other alloys,\nadding 1wt%, 3wt% and 5wt% copper with this eutectoid composition, were molded\nin permanent metal mould. Microscopic studies exhibited varied grains which\nconfirmed the formation of different phases. Moreover, the formation of\ndifferent phases in micro study was supported by XRD analysis. Hardness of the\nsamples were tested on Rockwell B scale and it was observed that the hardness\nof these alloys was substantially increased with the addition of copper. With\nincreasing amount of copper, phase changing temperature of the alloys reveals a\ngrowing trend, which was observed by DTA analysis. From this study it was\nconcluded that addition of copper can significantly add to the mechanical\nproperties of Zn-Al alloys."
    },
    {
        "anchor": "Tensile strain induced changes in the optical spectra of SrTiO3\n  epitaxial thin films: Effect of biaxial tensile strains on optical functions and band edge\ntransitions of ultra thin epitaxial films was studied using as an example a 13\nnm thick SrTiO3 films deposited on KTaO3(100) single-crystal substrates.\nOptical functions were determined by spectroscopic ellipsometry technique. It\nwas found that tensile strains result in a shift of the low energy band gap\noptical transitions to higher energies and decrease the refractive index in the\nvisible region. Comparison of the optical spectra for strained SrTiO3 films and\nfor homoepitaxial strain-free SrTiO3:Cr (0.01 %at.) films deposited on\nSrTiO3(100) single crystalline substrates showed that this shift could not be\nrelated to technological imperfections or to reduced thickness. The observed\neffect is connected with changes in the lowest conduction and in the top\nvalence bands that are due to increase of the in-plane lattice constant and/or\nonset of polar phase in the tensile strain-induced ultra-thin epitaxial SrTiO3\nfilms.",
        "positive": "Cu metal / Mn phthalocyanine organic spinterfaces atop Co with high spin\n  polarization at room temperature: The organic spinterface describes the spin-polarized properties that develop,\ndue to charge transfer, at the interface between a ferromagnetic metal (FM) and\nthe molecules of an organic semiconductor. Yet, if the latter is also magnetic\n(e.g. molecular spin chains), the interfacial magnetic coupling can generate\ncomplexity within magnetotransport experiments. Also, assembling this interface\nmay degrade the properties of its constituents (e.g. spin crossover or\nnon-sublimable molecules). To circumvent these issues, one can separate the\nmolecular and FM films using a less reactive nonmagnetic metal (NM).\nSpin-resolved photoemission spectroscopy measurements on the prototypical\nsystem Co(001)//Cu/Mnphthalocyanine (MnPc) reveal that the Cu/MnPc spinterface\natop ferromagnetic Co is highly spin-polarized at room temperature, up to Cu\nspacer thicknesses of at least 10 monolayers. Ab-initio theory describes a spin\npolarization of the topmost Cu layer after molecular hybridization that can be\naccompanied by magnetic hardening effects. This spinterface's unexpected\nrobustness paves the way for 1) integrating electronically fragile molecules\nwithin organic spinterfaces, and 2) manipulating molecular spin chains using\nthe well-documented spin transfer torque properties of the FM/NM bilayer."
    },
    {
        "anchor": "Critical behavior and magnetic relaxation dynamics of Nd0.4Sr0.6MnO3\n  nanoparticles: Detailed dc and ac magnetic properties of chemically synthesized\nNd0.4Sr0.6MnO3 with different particle size (down to 27 nm) have been studied\nin details. We have found ferromagnetic state in the nanoparticles, whereas,\nthe bulk Nd0.4Sr0.6MnO3 is known to be an A-type antiferromagnet. A\nGriffiths-like phase has also been identified in the nanoparticles. Further,\ncritical behavior of the nanoparticles has been studied around the second order\nferromagnetic-paramagnetic transition region (|(T-TC)/TC|{\\pounds} 0.04) in\nterms of modified Arrott plot, Kouvel-Fisher plot and critical isotherm\nanalysis. The estimated critical exponents (b,g,d) are quite different from\nthose predicted according to three-dimensional mean-field, Heisenberg and Ising\nmodels. This signifies a quite unusual nature of the size-induced ferromagnetic\nstate in Nd0.4Sr0.6MnO3. The nanoparticles are found to be interacting and do\nnot behave like ideal superparamagnet. Interestingly, we find spin glass like\nslow relaxation of magnetization, aging and memory effect in the nanometric\nsamples. These phenomena have been attributed to very broad distribution of\nrelaxation time as well as to inter-particle interaction. Experimentally, we\nhave found out that the dynamics of the nanoparticle systems can be best\ndescribed by hierarchical model of spin glasses.",
        "positive": "Competitive interfacial charge transfer to graphene from the electrode\n  contacts and surface adsorbates: Charge transfer (CT) at metal-graphene contacts induces a potential variation\nfrom the contact edges that extends to ~1 micrometer. Potential variations with\na similar length should be observed around charge-transferring surface\nadsorbates. Thus, it is expected that a competition exists between these two CT\nsources when one source is within ~1 micrometer from the other. In this letter,\nweakly-coupled Ni contacts and 7,7,8,8-tetracyanoquinodimethan molecules are\nemployed as the CT sources to investigate their possible competition. The CT\nfrom the molecules adsorbed only in the channel region change the charge\ndensity of the graphene in the under-contact regions. The extent of the CT\neffect in the under-contact region is as long as ~4 micrometers. The\nconsiderably long CT is ascribed to the high effective dielectric constant of\nthe graphene under the contacts, resulting from a thin interfacial NiOx layer\ncontaining carbon impurities acquired from the graphene."
    },
    {
        "anchor": "Reduction of g-factor due to Rashba effect in graphene: Graphene is a highly promising material in the field of spin electronics.\nRecent experiments on electron spin resonance have observed a reduction in the\ng-factor of graphene. In our previous paper [J. Phys. Soc. Jpn. 88, 094707\n(2019)], we demonstrated that one of sources for this reduction is the\ndiamagnetic property of graphene. However, the diamagnetic property by itself\ndoes not fully account for the magnitude of the reduction observed in the\nexperiments. In this paper, we focus on the Rashba effect, which is caused by\nthe work function existing near the surface of graphene. The Rashba effect\ntilts the spin magnetic moment to the in-plane direction of the graphene sheet,\npotentially reducing the g-factor. We evaluate this reduction using a simple\nmodel system incorporating the Rashba and spin Zeeman effects. We then\ndemonstrate that the resultant g-factor is in close agreement with that\nobserved in the prior experiments, indicating that the Rashba effect is able to\naccount for the remaining reduction in the g-factor of graphene.",
        "positive": "Hand in Hand Evolution of b-relaxation and Boson Peak in Metallic\n  Glasses: Boson peak and beta-relaxation are two intrinsic and markedly different\ndynamic modes of glasses, and their structural origins are long-standing\nissues. Through tuning atomic packing of a model metallic glass with\nmicroalloying of different types of elements, we find that low-temperature\nboson heat capacity peak evolves hand in hand with high-temperature\nbeta-relaxation. A linear correlation between the boson peak temperature and\nthe activation energy of beta-relaxation is disclosed. The coupling of the\nboson peak and the beta-relaxation indicates their common structural origin of\nthe loosely packed regions in metallic glasses."
    },
    {
        "anchor": "Time- and angle-resolved photoelectron spectroscopy of strong-field\n  light-dressed solids: prevalence of the adiabatic band picture: In recent years, strong-field physics in condensed-matter was pioneered as a\nnovel approach for controlling material properties through laser-dressing, as\nwell as for ultrafast spectroscopy via nonlinear light-matter interactions\n(e.g. harmonic generation). A potential controversy arising from these\nadvancements is that it is sometimes vague which band-picture should be used to\ninterpret strong-field experiments: the field-free bands, the adiabatic\n(instantaneous) field-dressed bands, Floquet bands, or some other intermediate\npicture. We here try to resolve this issue by performing 'theoretical\nexperiments' of time- and angle-resolved photoelectron spectroscopy (Tr-ARPES)\nfor a strong-field laser-pumped solid, which should give access to the actual\nobservable bands of the irradiated material. To our surprise, we find that the\nadiabatic band-picture survives quite well, up to high field intensities\n(~10^12 W/cm^2), and in a wide frequency range (driving wavelengths of 4000 to\n800nm, with Keldysh parameters ranging up to ~7). We conclude that to first\norder, the adiabatic instantaneous bands should be the standard blueprint for\ninterpreting ultrafast electron dynamics in solids when the field is highly\noff-resonant with characteristic energy scales of the material. We then discuss\nweaker effects of modifications of the bands beyond this picture that are\nnon-adiabatic, showing that by using bi-chromatic fields the deviations from\nthe standard picture can be probed with enhanced sensitivity. Our work outlines\na clear band picture for the physics of strong-field interactions in solids,\nwhich should be useful for designing and analyzing strong-field experimental\nobservables and also to formulate simpler semi-empirical models.",
        "positive": "Optoelectronic properties of a photosystem I - carbon nanotube hybrid\n  system: The photoconductance properties of photosystem I (PSI) covalently bound to\ncarbon nanotubes (CNTs) are measured. We demonstrate that the PSI forms active\nelectronic junctions with the CNTs enabling control of the CNTs\nphotoconductance by the PSI. In order to electrically contact the photoactive\nproteins, a cysteine mutant is generated at one end of the PSI by genetic\nengineering. The CNTs are covalently bound to this reactive group using\ncarbodiimide chemistry. We detect an enhanced photoconductance signal of the\nhybrid material at photon wavelengths resonant to the absorption maxima of the\nPSI compared to nonresonant wavelengths. The measurements prove that it is\nfeasible to integrate photosynthetic proteins into optoelectronic circuits at\nthe nanoscale."
    },
    {
        "anchor": "Interplay of structure and spin-orbit strength in magnetism of\n  metal-benzene sandwiches: from single molecules to infinite wires: Based on first-principles density functional theory calculations we explore\nelectronic and magnetic properties of experimentally producible sandwiches and\ninfinite wires made of repeating benzene molecules and transition-metal atoms\nof V, Nb, and Ta. We describe the bonding mechanism in the molecules and in\nparticular concentrate on the origin of magnetism in these structures. We find\nthat all the considered systems have sizable magnetic moments and ferromagnetic\nspin-ordering, with the single exception of the V3-Bz4 molecule. By including\nthe spin-orbit coupling into our calculations we determine the easy and hard\naxes of the magnetic moment, the strength of the uniaxial magnetic anisotropy\nenergy (MAE), relevant for the thermal stability of magnetic orientation, and\nthe change of the electronic structure with respect to the direction of the\nmagnetic moment, important for spin-transport properties. While for the V-based\ncompounds the values of the MAE are only of the order of 0.05-0.5 meV per metal\natom, increasing the spin-orbit strength by substituting V with heavier Nb and\nTa allows to achieve an increase in anisotropy values by one to two orders of\nmagnitude. The rigid stability of magnetism in these compounds together with\nthe strong ferromagnetic ordering makes them attractive candidates for\nspin-polarized transport applications. For a Nb-benzene infinite wire the\noccurrence of ballistic anisotropic magnetoresistance is demonstrated.",
        "positive": "Direct Optical Coupling to an Unoccupied Dirac Surface State in the\n  Topological Insulator Bi$_2$Se$_3$: We characterize the occupied and unoccupied electronic structure of the\ntopological insulator Bi$_2$Se$_3$ by one-photon and two-photon angle-resolved\nphotoemission spectroscopy and slab band structure calculations. We reveal a\nsecond, unoccupied Dirac surface state with similar electronic structure and\nphysical origin to the well-known topological surface state. This state is\nenergetically located 1.5 eV above the conduction band, which permits it to be\ndirectly excited by the output of a Ti:Sapphire laser. This discovery\ndemonstrates the feasibility of direct ultrafast optical coupling to a\ntopologically protected, spin-textured surface state."
    },
    {
        "anchor": "Photoconductivity of an intrinsic graphen: We examine the photoconductivity of an intrinsic graphene associated with\nfar- and mid-infrared irradiation at low temperatures. The model under\nconsideration accounts for the excitation of the electron-hole pairs by\nincident radiation, the interband generation-recombination transitions due to\nthermal radiation, and the intraband energy relaxation due to acoustic phonon\nscattering. The momentum relaxation is assumed to be caused by elastic\nscattering. The pertinent collision integrals are adapted for the case of the\nmassless energy spectrum of carriers that interact with the longitudinal\nacoustic mode and the thermal radiation. It is found that the photoconductivity\nis determined by an interplay between weak energy relaxation and\ngeneration-recombination processes. Due to this the threshold of nonlinear\nresponse is fairly low.",
        "positive": "Adsorption-controlled growth of MnTe(Bi2Te3)n by molecular beam epitaxy\n  exhibiting stoichiometry-controlled magnetism: We report the growth of the intrinsic magnetic topological system\nMnTe(Bi2Te3)n by molecular beam epitaxy. By mapping the temperature and the\nBi:Mn flux ratio, it is shown that there is a narrow growth window for the n=1\nphase MnBi2Te4 with 2.0<Bi:Mn<2.6 at 225 {\\deg}C. Here the films are\nstoichiometric and excess Bi and Te is not incorporated. At higher flux ratios\n(Bi:Mn>4.5) it is found that the n = 2 MnBi4Te7 phase is stabilized. Transport\nmeasurements indicate that the MnBi2Te4 and MnBi4Te7 undergo magnetic\ntransitions around 25 K, and 10 K, respectively, consistent with\nantiferromagnetic phases found in the bulk. Further, for Mn-rich conditions\n(Bi:Mn<2), ferromagnetism emerges that exhibits a clear hysteretic state in the\nHall effect, which likely indicates Mn-doped MnBi2Te4. Understanding how to\ngrow ternary chalcogenide phases is the key to synthesizing new materials and\nto interface magnetism and topology, which together are routes to realize and\ncontrol exotic quantum phenomena."
    },
    {
        "anchor": "Some Limitations of Dislocation Walls as Models for Plastic Boundary\n  Layers: It has recently become popular to analyze the behavior of excess dislocations\nin plastic deformation under the assumption that such dislocations are arranged\ninto walls with periodic dislocation spacing along the wall direction. This\nassumption is made plausible by the fact that periodic walls represent minimum\nenergy arrangements for dislocations of the same sign, and it allows to use the\nanalytically known short-ranged stress fields of such walls for analyzing the\nstructure of plastic boundary layers. Here we show that unfortunately both the\nidea that dislocation walls are low-energy configurations and the properties of\ntheir interactions depend critically on the assumption of a periodic\narrangement of dislocations within the walls. Once this assumption is replaced\nby a random arrangement, the properties of dislocation walls change completely.",
        "positive": "Investigating finite-size effects in molecular dynamics simulations of\n  ion diffusion, heat transport, and thermal motion in superionic materials: The effects of the finite size of the simulation box in equilibrium molecular\ndynamics simulations are investigated for prototypical superionic conductors of\ndifferent types, namely the fluorite-structure materials PbF2, CaF2, and UO2\n(type-II), and the {\\alpha} phase of AgI (type I). Largely validated empirical\nforce-fields are employed to run ns-long simulations and extract general trends\nfor several properties, at increasing size and in a wide temperature range.\nThis work shows that, for the considered type-II superionic conductors, the\ndiffusivity dramatically depends on the system size and that the superionic\nregime is shifted to larger temperatures in smaller cells. Furthermore, only\nsimulations of several hundred atoms are able to capture the\nexperimentally-observed, characteristic change in the activation energy of the\ndiffusion process, occurring at the order-disorder transition to the superionic\nregime. Finite-size effects on ion diffusion are instead much weaker in\n{\\alpha}-AgI. The thermal conductivity is found generally smaller for smaller\ncells, where the temperature-independent (Allen-Feldman) regime is also reached\nat significantly lower temperatures. The finite-size effects on the thermal\nmotion of the non-mobile ions composing the solid matrix follow the simple law\nwhich holds for solids."
    },
    {
        "anchor": "Field Orientation Dependent Magnetic Phases In Weyl Semimetal Co3Sn2S2: Magnetism plays a key role in the emergence of topological phenomena in the\nWeyl semimetal Co3Sn2S2, which exhibits a ferromagnetic (FM) interactions along\nthe c-axis of the crystal and an antiferromagnetic (AFM) interactions within\nthe ab plane. Extensive studies on the temperature dependence of the magnetism\nwith the magnetic field along the c-axis have uncovered a number of magnetic\nphases. Currently, the nature and origins of the reported magnetic phases are\nunder debate. Here we report on magnetic field orientation effects on the\nmagnetism in Co3Sn2S2. The shape of the hysteresis loop of the Hall resistance\nat a fixed temperature is found to change from rectangular to bow-tie-like as\nthe magnetic field is tilted from the c-axis towards the ab plane, resembling\nthat reported for magnetic fields along the c-axis as the temperature\napproaches the Curie temperature from below. Unlike their temperature-dependent\ncounterparts, the newly observed bow-tie-like hysteresis loops show exchange\nbias. Our results showcase the contribution of the in-plane AFM interactions to\nthe magnetism in Co3Sn2S2 and demonstrate a new way to tune its magnetic\nphases. They also shed light on the temperature-dependent magnetic phases\noccurring in the magnetic field along the c-axis of the crystal.",
        "positive": "X-Ray Studies of Nanoporous Gold: Powder Diffraction by Large Crystals\n  with Small Holes: X-ray diffraction studies of nanoporous gold face the poorly understood\ndiffraction scenario where large coherent crystals are riddled with nanoscale\nholes. Theoretical considerations derived in this study show that the ligament\nsize of the porous network influences the scattering despite being quasi single\ncrystalline. Virtual diffraction of artificially generated samples confirms the\nresults but also shows a loss of long-range coherency and the appearance of\nmicrostrain due to thermal relaxation. Subsequently, a large set of laboratory\nX-ray investigations of nanoporous gold fabricated by different approaches and\nsynthesis parameters reveal a clear correlation between ligament size and size\nof the coherent scattering domains as well as extremely high microstrains in\nsamples with ligament sizes below 10 nm."
    },
    {
        "anchor": "Temperature-dependent Fermi surface probed by Shubnikov-de Haas\n  oscillations in topological semimetal candidates DyBi and HoBi: Rare earth-based monopnictides are among the most intensively studied groups\nof materials in which extremely large magnetoresistance has been observed. This\nstudy explores magnetotransport properties of two representatives of this\ngroup, DyBi and HoBi. The extreme magnetoresistance is discovered in DyBi and\nconfirmed in HoBi. At $T=2$ K and in $B=14$ T for both compounds,\nmagnetoresistance reaches the order of magnitude of $10^4\\%$. For both\nmaterials, standard Kohler's rule is obeyed only in the temperature range from\n50 K to 300 K. At lower temperatures, extended Kohler's rule has to be invoked\nbecause carrier concentrations and mobilities strongly change with temperature\nand magnetic field. This is further proven by the observation of a quite rare\ntemperature-dependence of oscillation frequencies in Shubnikov-de Haas effect.\nRate of this dependence clearly changes at N\\'{e}el temperature, reminiscent of\na novel magnetic band splitting. Multi-frequency character of the observed\nShubnikov-de Haas oscillations points to the coexistence of electron- and\nhole-type Fermi pockets in both studied materials. Overall, our results\nhighlight correlation of temperature dependence of the Fermi surface with the\nmagnetotransport properties of DyBi and HoBi.",
        "positive": "Control of the chirality and polarity of magnetic vortices in triangular\n  nanodots: Magnetic vortex dynamics in lithographically prepared nanodots is currently a\nsubject of intensive research, particularly after recent demonstration that the\nvortex polarity can be controlled by in-plane magnetic field. This has\nstimulated the proposals of non-volatile vortex magnetic random access\nmemories. In this work, we demonstrate that triangular nanodots offer a real\nalternative where vortex chirality, in addition to polarity, can be controlled.\nIn the static regime, we show that vortex chirality can be tailored by applying\nin-plane magnetic field, which is experimentally imaged by means of\nVariable-Field Magnetic Force Microscopy. In addition, the polarity can be also\ncontrolled by applying a suitable out-of-plane magnetic field component. The\nexperiment and simulations show that to control the vortex polarity, the\nout-of-plane field component, in this particular case, should be higher than\nthe in-plane nucleation field. Micromagnetic simulations in the dynamical\nregime show that the magnetic vortex polarity can be changed with\nshort-duration magnetic field pulses, while longer pulses change the vortex\nchirality."
    },
    {
        "anchor": "Nanotube field of C60 molecules in carbon nanotubes: atomistic versus\n  continuous tube approach: We calculate the van der Waals energy of a C60 molecule when it is\nencapsulated in a single-walled carbon nanotube with discrete atomistic\nstructure. orientational degrees of freedom and longitudinal displacements of\nthe molecule are taken into account, and several achiral and chiral carbon\nnanotubes are considered. A comparison with earlier work where the tube was\napproximated by a continuous cylindrical distribution of carbon atoms is made.\nWe find that such an approximation is valid for high and intermediate tube\nradii; for low tube radii, minor chirality effects come into play. Three\nmolecular orientational regimes are found when varying the nanotube radius.",
        "positive": "Micron-scale deformation: a coupled in-situ study of strain bursts and\n  acoustic emission: Plastic deformation of micron-scale crystalline materials differ considerably\nfrom bulk ones, because it is characterized by random strain bursts. To obtain\na detailed picture about this stochastic phenomenon, micron sized pillars have\nbeen fabricated and compressed in the chamber of a SEM. An improved FIB\nfabrication method is proposed to get non-tapered micro-pillars with a maximum\ncontrol over their shape. The in-situ compression device developed allows high\naccuracy sample positioning and force/displacement measurements with high data\nsampling rate. The collective avalanche-like motion of dislocations appears as\nstress drops on the stress-strain curve. To confirm that these stress drops are\ndirectly related to dislocation activity, and not to some other effect, an\nacoustic emission transducer has been mounted under the sample to record\nemitted acoustic activity during strain-controlled compression tests of Al-5\\%\nMg micro-pillars. The correlation between the stress drops and the acoustic\nemission signals indicates that indeed dislocation avalanches are responsible\nfor the stochastic character of the deformation process."
    },
    {
        "anchor": "Second-order and real Chern topological insulator in twisted bilayer\n  $\u03b1$-graphyne: The study of higher-order and real topological states as well as the material\nrealization have become a research forefront of topological condensed matter\nphysics in recent years. Twisted bilayer graphene (tbG) is proved to have\nhigher-order and real topology. However whether this conclusion can be extended\nto other two-dimensional twisted bilayer carbon materials and the mechanism\nbehind it lack explorations. In this paper, we identify the twisted bilayer\n$\\alpha$-graphyne (tbGPY) at large twisting angle as a real Chern insulator\n(also known as Stiefel-Whitney insulator) and a second-order topological\ninsulator. Our first-principles calculations suggest that the tbGPY at\n21.78$^\\circ$ is stable at 100 K with a larger bulk gap than the tbG. The\nnon-trivial topological indicators, including the real Chern number and a\nfractional charge, and the localized in-gap corner states are demonstrated from\nfirst-principles and tight-binding calculations. Moreover, with $\\mathcal\nC_{6z}$ symmetry, we prove the equivalence between the two indicators, and\nexplain the existence of the corner states. To decipher the real and\nhigher-order topology inherited from the Moir\\'e heterostructure, we construct\nan effective four band tight-binding model capturing the topology and\ndispersion of the tbGPY at large twisting angle. A topological phase transition\nto a trivial insulator is demonstrated by breaking the $\\mathcal C_{2y}$\nsymmetry of the effective model, which gives insights on the trivialization of\nthe tbGPY as reducing the twisting angle to 9.43$^\\circ$ suggested by our\nfirst-principles calculations.",
        "positive": "Full band Monte Carlo simulation of AlInAsSb digital alloys: Avalanche photodiodes fabricated from AlInAsSb grown as a digital alloy\nexhibit low excess noise. In this paper, we investigate the band\nstructure-related mechanisms that influence impact ionization. Band-structures\ncalculated using an empirical tight-binding method and Monte Carlo simulations\nreveal that the mini-gaps in the conduction band do not inhibit electron impact\nionization. Good agreement between the full band Monte Carlo simulations and\nmeasured noise characteristics is demonstrated."
    },
    {
        "anchor": "Optical read-out and control of antiferromagnetic Neel vector in\n  altermagnets and beyond: Finding methods for the most efficient and fastest detection and control of\nmagnetic domains in antiferromagnets is presently among the main challenges of\nmagnetic research at large. We analyse the problem of optical read-out and\ncontrol of the antiferromagnetic Neel vector using symmetry analysis and the\nprinciples of equilibrium thermodynamics. Following the pioneering approach of\nDzyaloshinksii, we divide all antiferromagnets in three classes. It is shown\nthat, using the magneto-optical Faraday effect or other effects which scale\nlinearly with the antiferromagnetic Neel vector, it is possible to distinguish\nantiferromagnetic domains with mutually opposite N\\'eel vectors in two of the\nthree classes. Symmetry properties of one of these two classes are similar to\nthose of altermagnets. The analysis also reveals multiple mechanisms to\ndirectly excite spins with light for practically every type of antiferromagnet.",
        "positive": "Free-electron effects on optical absorption of hybrid perovskite\n  CH$_3$NH$_3$PbI$_3$ from first principles: Hybrid organic-inorganic perovskites, such as methyl-ammonium lead tri-iodide\n(MAPbI$_3$), are interesting candidates for efficient absorber materials in\nnext-generation solar cells, partly due to an unusual combination of low\nexciton binding energy and strong optical absorption. Excitonic effects in this\nmaterial have been subject to debate both for experiment and theory, indicating\na need for better understanding of the screening mechanisms that act upon the\nelectron-hole interaction. Here we use cutting-edge first-principles\ntheoretical spectroscopy, based on density-functional and many-body\nperturbation theory, to study atomic geometries, electronic structure, and\noptical properties of three MAPbI$_3$ polymorphs and find good agreement with\nearlier results and experiment. We then study the influence of free electrons\non the electron-hole interaction and show that this explains consistently\nsmaller exciton binding energies, compared to those in the material without\nfree electrons. Interestingly, we also find that the absorption line shape\nstrongly resembles that of the spectrum without free electrons up to high free\nelectron concentrations. We explain this unexpected behavior by formation of\nMahan excitons that dominate the absorption edge, making it robust against\nfree-electron induced changes observed in other semiconductors."
    },
    {
        "anchor": "Quantitative analysis of the first-principles effective-Hamiltonian\n  approach to ferroelectric perovskites: The various approximations used in the construction of a first-principles\neffective Hamiltonian for BaTiO3, and their effects on the calculated\ntransition temperatures, are discussed. An effective Hamiltonian for BaTiO3 is\nconstructed not from first-principles calculations, but from the structural\nenergetics of an atomistic shell model for BaTiO3 of Tinte et al. This allows\nthe elimination of certain uncontrolled approximations that arise in the\ncomparison of first-principles effective Hamiltonian results with experimental\nvalues and the quantification of errors associated with the selection of the\neffective Hamiltonian subspace and subsequent projection. The discrepancies in\ntransition temperatures computed in classical simulations for this effective\nHamiltonian and for the atomistic shell model are shown to be associated\nprimarily with a poor description of the thermal expansion in the former case.\nThis leads to specific proposals for refinements to the first-principles\neffective Hamiltonian method. Our results suggest that there are at least two\nsignificant sources of error in the effective-Hamiltonian treatment of BaTiO3\nin the literature, i.e., the improper treatment of thermal expansion, and the\nerrors inherent in the first-principles approach itself.",
        "positive": "Two distinct metallic bands associated with monatomic Au wires on the\n  Si(557)-Au surface: The Si(557)-Au surface, containing monatomic Au wires parallel to the steps,\nhas been proposed as an experimental realization of an ideal one-dimensional\nmetal. In fact, recent photoemission experiments on this system (Nature 402,\n504 (1999)) found two peaks that were interpreted in terms of the spin-charge\nseparation in a Luttinger liquid. Our first-principles density functional\ncalculations reveal two metallic bands associated with Au-Si bonds, instead of\nthe single band expected from the Au 6s states, providing an alternative\nexplanation for the experimental observations."
    },
    {
        "anchor": "Temperature-induced inversion of the spin-photogalvanic effect in\n  WTe$_2$ and MoTe$_2$: We investigate the generation and temperature-induced evolution of\noptically-driven spin photocurrents in WTe$_2$ and MoTe$_2$. By correlating the\nscattering-plane dependence of the spin photocurrents with the symmetry\nanalysis, we find that a sizeable spin photocurrent can be controllably driven\nalong the chain direction by optically exciting the system in the high-symmetry\n$y$-$z$ plane. Temperature dependence measurements show that pronounced\nvariations in the spin photocurrent emerge at temperatures that coincide with\nthe onset of anomalies in their transport and optical properties. The\ndecreasing trend in the temperature dependence starting below 150 K is\nattributed to the temperature-induced Lifshitz transition. The sign inversion\nof the spin photocurrent, observed around 50 K in WTe$_2$ and around 120 K in\nMoTe$_2$, may have its origin in an interaction that involves multiple kinds of\ncarriers.",
        "positive": "An application of the catastrophe theory to building the model of\n  elastic-plastic behaviour of materials. An application of the catastrophe\n  theory to building the model of elastic-plastic behaviour of materials. Part\n  1. Uniaxial deformation (stress): The uniaxial elastic-plastic deformation process is considered. Mathematical\nmodel of this process was built. According to this model all stable static\nstates form the lattice, which is called the delta-lattice."
    },
    {
        "anchor": "Spin injection into vanadium dioxide films from a typical ferromagnetic\n  metal, across the metal-insulator transition of the vanadium dioxide films: A vanadium dioxide VO2 film shows metal-insulator transition (MIT) induced by\nchanging environmental temperature. We report the temperature dependence of\nelectromotive force properties generated in VO2/Ni80Fe20 bilayer junctions\nunder the ferromagnetic resonance (FMR) of the Ni80Fe20 layer. An electromotive\nforce generated in a VO2/Ni80Fe20 bilayer junction under the FMR showed a small\nchange across the MIT temperature of the VO2 film, while the VO2 film\nresistance drastically changed. This behavior was not only explained with the\ntemperature dependence of the electromotive force property generated in the\nNi80Fe20 film itself under the FMR, but also with the generated electromotive\nforces due to the inverse spin-Hall effect (ISHE) in the VO2 film under the FMR\nof the Ni80Fe20 film. That is, we successfully demonstrated the spin injection\nfrom a Ni80Fe20 film into a VO2 film across the MIT temperature of the VO2\nfilm.",
        "positive": "Electron spin relaxation in semiconducting carbon nanotubes: the role of\n  hyperfine interaction: A theory of electron spin relaxation in semiconducting carbon nanotubes is\ndeveloped based on the hyperfine interaction with disordered nuclei spins I=1/2\nof $^{13}$C isotopes. It is shown that strong radial confinement of electrons\nenhances the electron-nuclear overlap and subsequently electron spin relaxation\n(via the hyperfine interaction) in the carbon nanotubes. The analysis also\nreveals an unusual temperature dependence of longitudinal (spin-flip) and\ntransversal (dephasing) relaxation times: the relaxation becomes weaker with\nthe increasing temperature as a consequence of the particularities in the\nelectron density of states inherent in one-dimensional structures. Numerical\nestimations indicate relatively high efficiency of this relaxation mechanism\ncompared to the similar processes in bulk diamond. However, the anticipated\nspin relaxation time of the order of 1 s in CNTs is still much longer than\nthose found in conventional semiconductor structures."
    },
    {
        "anchor": "Non-Reciprocal Wave Propagation in Spatiotemporal Periodic Structures: We study longitudinal and transverse wave propagation in beams with elastic\nproperties that are periodically varying in space and time. Spatiotemporal\nmodulation of the elastic properties breaks mechanical reciprocity and induces\none-way propagation. We follow an analytic approach to characterize the\nnon-reciprocal behavior of the structures by analyzing the symmetry breaking of\nthe dispersion spectrum, which results in the formation of directional band\ngaps and produces shifts of the First Brilloin Zone limits. This approach\nallows us to relate position and width of the directional band gaps to the\nmodulation parameters. Moreover, we identify the critical values of the\nmodulation speed to maximize the non-reciprocal effect. We numerically verify\nthe theoretical predictions by using a finite element model of the modulated\nbeams to compute the transient response of the structure. We compute the\ntwo-dimensional Fourier transform of the collected displacement fields to\ncalculate numerical band diagrams, showing excellent agreement between\ntheoretical and numerical dispersion diagrams.",
        "positive": "k-Resolved electronic structure of buried heterostructure and impurity\n  systems by soft-X-ray ARPES: Angle-resolved photoelectron spectroscopy (ARPES) is the main experimental\ntool to explore electronic structure of solids resolved in the electron\nmomentum k . Soft-X-ray ARPES (SX-ARPES), operating in a photon energy range\naround 1 keV, benefits from enhanced probing depth compared to the conventional\nVUV-range ARPES, and elemental/chemical state specificity achieved with\nresonant photoemission. These advantages make SX-ARPES ideally suited for\nburied heterostructure and impurity systems, which are at the heart of current\nand future electronics. These applications are illustrated here with a few\npioneering results, including buried quantum-well states in semiconductor and\noxide heterostructures, their bosonic coupling critically affecting electron\ntransport, magnetic impurities in diluted magnetic semiconductors and\ntopological materials, etc. High photon flux and detection efficiency are\ncrucial for pushing the SX-ARPES experiment to these most photon-hungry cases."
    },
    {
        "anchor": "Optical properties of silicon rich silicon nitride (SixNyHz) from first\n  principles: The real and imaginary parts of the complex refractive index of SixNyHz have\nbeen calculated using density functional perturbation theory. Optical spectra\nfor reflectivity, adsorption coefficient, energy-loss function (ELF), and\nrefractive index, are obtained. The results for Si3N4 are in agreement with the\navailable theoretical and experimental results. To understand the electron\nenergy loss mechanism in Si rich silicon nitride, the influence of the Si\ndoping rate, of the positions of the dopants, and of H in and on the surface on\nthe ELF have been investigated. It has been found that all defects, such as\ndangling bonds in the bulk and surfaces, increase the intensity of the ELF in\nthe low energy range (below 10 eV). H in the bulk and on the surface has a\nhealing effect, which can reduce the intensity of the loss peaks by saturating\nthe dangling bonds. Electronic structure analysis has confirmed the origin of\nthe changes in the ELF. It has demonstrated that the changes in ELF is not only\naffected by the composition but also by the microstructures of the materials.\nThe results can be used to tailor the optical properties, in this case the ELF\nof Si rich Si3N4, which is essential for secondary electron emission\napplication.",
        "positive": "Non-Crystalline Structures of Ultra-Thin Unsupported Nanowires: Computer simulations suggest that ultrathin metal wires should develop\nexotic, non-crystalline stable atomic structures, once their diameter decreases\nbelow a critical size of the order of a few atomic spacings. The new\nstructures, whose details depend upon the material and the wire thickness, may\nbe dominated by icosahedral packings. Helical, spiral-structured wires with\nmulti-atom pitches are also predicted. The phenomenon, analogous to the\nappearance of icosahedral and other non-crystalline shapes in small clusters,\ncan be rationalized in terms of surface energy anisotropy and optimal packing."
    },
    {
        "anchor": "Magnetic hexadecapole order and magnetopiezoelectric metal in\n  Ba$_{1-x}$K$_x$Mn$_2$As$_2$: We study an odd-parity magnetic multipole order in\nBa$_{1-x}$K$_x$Mn$_2$As$_2$ and related materials. Although BaMn$_2$As$_2$ is a\nseemingly conventional Mott insulator with G-type antiferromagnetic order, we\nidentify the ground state as a magnetic hexadecapole ordered state accompanied\nby simultaneous time-reversal and space-inversion symmetry breaking. A symmetry\nargument and microscopic calculations reveal the ferroic ordering of leading\nmagnetic hexadecapole moment and admixed magnetic quadrupole moment.\nFurthermore, we clarify electromagnetic responses characterizing the magnetic\nhexadecapole state of semiconducting BaMn$_2$As$_2$ and doped metallic systems.\nA magnetoelectric effect and antiferromagnetic Edelstein effect are shown.\nInterestingly, a counter-intuitive currentinduced nematic order occurs in the\nmetallic state. The electric current along the \\textit{z}-axis induces the\n\\textit{xy}-plane nematicity in sharp contrast to the spontaneous nematic order\nin superconducting Febased 122-compounds. Thus, the magnetic hexadecapole state\nof doped BaMn$_2$As$_2$ is regarded as a magnetopiezoelectric metal. The\nanomalous responses stem from the peculiar symmetry of the parity-violating\nmagnetic order. Other candidate materials for magnetic hexadecapole order are\nproposed.",
        "positive": "Preferential Composition during Nucleation and Growth in Multi-Principal\n  Elements Alloys: The crystallization of complex, concentrated alloys can result in\natomic-level short-range order, composition gradients, and phase separation.\nThese features govern the properties of the resulting alloy. While nucleation\nand growth in single-element metals are well understood, several open questions\nremain regarding the crystallization of multi-principal component alloys. We\nuse MD to model the crystallization of a five-element, equiatomic alloy modeled\nafter CoCrCuFeNi upon cooling from the melt. Stochastic, homogeneous nucleation\nresults in nuclei with a biased composition distribution, rich in Fe and Co.\nThis deviation from the random sampling of the overall composition is driven by\nthe internal energy and affects nuclei of a wide range of sizes, from tens of\natoms all the way to super-critical sizes. This results in short range order\nand compositional gradients at nanometer scales."
    },
    {
        "anchor": "CO2 packing polymorphism under confinement in cylindrical nanopores: We investigate the effect of cylindrical nano-confinement on the phase\nbehaviour of a rigid model of carbon dioxide using both molecular dynamics and\nwell tempered metadynamics. To this aim we study a simplified pore model across\na parameter space comprising pore diameter, CO2-pore wall potential and CO2\ndensity. In order to systematically identify ordering events within the pore\nmodel we devise a generally applicable approach based on the analysis of the\ndistribution of intermolecular orientations. Our simulations suggest that,\nwhile confinement in nano-pores inhibits the formation of known crystal\nstructures, it induces a remarkable variety of ordered packings unrelated to\ntheir bulk counterparts, and favours the establishment of short range order in\nthe fluid phase. We summarise our findings by proposing a qualitative phase\ndiagram for this model.",
        "positive": "Valence-band satellite in the ferromagnetic nickel: LDA+DMFT study with\n  exact diagonalization: The valence-band spectrum of the ferromagnetic nickel is calculated using the\nLDA+DMFT method. The auxiliary impurity model emerging in the course of the\ncalculations is discretized and solved with the exact diagonalization, or, more\nprecisely, with the Lanczos method. Particular emphasis is given to spin\ndependence of the valence-band satellite that is observed around 6 eV below the\nFermi level. The calculated satellite is strongly spin polarized in accord with\nexperimental findings."
    },
    {
        "anchor": "Polarization rotation by external electric field in two-dimensional\n  antiferroelectric squaric acid, H$_2$C$_4$O$_4$: A pseudospin model for description of the influence of the electric field,\nconfined to the plane of sublattice polarization, on the two-dimensional\nsquaric acid antiferroelectrics is developed. The system behavior is analyzed\nin terms of the parameters of ferroelectric and antiferroelectric ordering, as\nwell as the non-collinearity angle $\\theta$, which is the angle between\nsublattice polarizations. The temperature-electric field $T-E_1$ phase diagram\nis constructed. Most of the field-induced transitions are found to be\nassociated with polarization rotation. The observed phases include the\ncollinear ferroelectric and non-collinear ferrielectric with almost\nantiparallel and perpendicular polarizations of the sublattices, respectively.\nThe diagram also contains two regions, where the non-collinearity angle varies\ncontinuously between, nominally, 0 and 90$^\\circ$ and between 90$^\\circ$ and\n180$^\\circ$. The first and second order transition lines, supercritical lines,\ncritical end points, and critical points on the $T-E_1$ phase diagram are\ndetected.",
        "positive": "Thermogravimetric study of the non-stoichiometric w\u00fcstite FeOx. Pseudo\n  phases w i and w' i . New T-P-X equilibrium phase diagram: A statistical numerical analysis of thermogravimetric measurements\n(temperature, mass variation, oxygen pressure) leads to a new equilibrium phase\ndiagram T-P-X of the iron monoxide or w\\\"ustite FeOx. Three varieties or pseudo\nphases W1, W2, W3 are revealed above 911 {\\textdegree}C, three others W'1, W'2,\nW'3 below. This diagram displays their subfields, and shows 25 invariant points\nbetween stable phases and 8 possible invariant points between metastable\nphases. A thermodynamic approach is pointed out, which makes possible to\ncharacterize the point defects and their clusters as components of the crystal\nlattice."
    },
    {
        "anchor": "Towards active learning: A stopping criterion for the sequential\n  sampling of grain boundary degrees of freedom: Many materials processes and properties depend on the anisotropy of the\nenergy of grain boundaries, i.e.~on the fact that this energy is a function of\nthe five geometric degrees of freedom (DOF) of the interface. To access this\nparameter space in an efficient way and to discover energy cusps in unexplored\nregions, a method was recently established, which combines atomistic\nsimulations with statistical methods 10.1002/adts.202100615. This sequential\nsampling technique is now extended in the spirit of an active learning\nalgorithm by adding a criterion to decide when the sampling has advanced enough\nto stop. In this instance, two parameters to analyse the sampling results on\nthe fly are introduced: the number of cusps, which correspond to the most\ninteresting and important regions of the energy landscape, and the maximum\nchange of energy between two sequential iterations. Monitoring these two\nquantities provides valuable insight into how the subspaces are energetically\nstructured. The combination of both parameters provides the necessary\ninformation to evaluate the sampling of the 2D subspaces of grain boundary\nplane inclinations of even non-periodic, low angle grain boundaries. With a\nreasonable number of data points in the initial design, only a few\nappropriately chosen sequential iterations already improve the accuracy of the\nsampling substantially and unknown cusps can be found within a few additional\nsequential steps.",
        "positive": "Hydrogen bubble nucleation by self-clustering: Density Functional Theory\n  and statistical models studies using tungsten as a model system: Low-energy hydrogen irradiation is known to induce bubble formation in\ntungsten, while its atomistic mechanisms remain little understood. Using\nfirst-principles calculations and statistical models, we studied the\nself-clustering behavior of hydrogen in tungsten. Unlike previous speculations\nthat hydrogen self-clusters are energetically unstable owing to the general\nrepulsion between two hydrogens, we demonstrated that hydrogen self-cluster\nbecomes more favorable as the cluster size increases. We found that hydrogen\natoms would form two-dimensional platelet-like structures along {100} planes.\nThese hydrogen self-clustering behaviors can be quantitative understood by the\ncompetition between long-ranged elastic attraction and local electronic\nrepulsion. Further statistical analysis showed that there exists a critical\nhydrogen concentration above which hydrogen self-clusters are thermodynamically\nstable and kinetically feasible. Based on this critical hydrogen concentration,\nthe plasma loading conditions under which hydrogen self-clusters form were\npredicted. Our predictions showed excellent agreement with experimental results\nof hydrogen bubble formation in tungsten exposed to low-energy hydrogen\nirradiation. Finally, we proposed a possible mechanism for the hydrogen bubble\nnucleation via hydrogen self-clustering. This work provides mechanistic\ninsights and quantitative models towards understanding of plasma-induced\nhydrogen bubble formation in plasma-facing tungsten."
    },
    {
        "anchor": "Quasiparticle Levels at Large Interface Systems from Many-body\n  Perturbation Theory: the XAF-GW method: We present a fully ab initio approach based on many-body perturbation theory\nin the GW approximation, to compute the quasiparticle levels of large interface\nsystems without significant covalent interactions between the different\ncomponents of the interface. The only assumption in our approach is that the\npolarizability matrix (chi) of the interface can be given by the sum of the\npolarizability matrices of individual components of the interface. We show\nanalytically, using a two-state hybridized model, that this assumption is valid\neven in the presence of interface hybridization to form bonding and\nanti-bonding states, up to first order in the overlap matrix elements involved\nin the hybridization. We validate our approach by showing that the band\nstructure obtained in our method is almost identical to that obtained using a\nregular GW calculation for bilayer black phosphorus, where interlayer\nhybridization is significant. Significant savings in computational time and\nmemory are obtained by computing chi only for the smallest sub-unit cell of\neach component, and expanding (unfolding) the chi matrix to that in the unit\ncell of the interface. To treat interface hybridization, the full wavefunctions\nof the interface are used in computing the self-energy. We thus call the method\nXAF-GW (X: eXpand-chi, A: Add-chi, F: Full wavefunctions). Compared to\nGW-embedding type approaches in the literature, the XAF-GW approach is not\nlimited to specific screening environments or to non-hybridized interface\nsystems. XAF-GW can also be applied to systems with different dimensionalities,\nas well as to Moire superlattices such as in twisted bilayers. We illustrate\nthe generality and usefulness of our approach by applying it to self-assembled\nPTCDA monolayers on Au(111) and Ag(111), and PTCDA monolayers on\ngraphite-supported monolayer WSe2, where good agreement with experiment is\nobtained.",
        "positive": "Antiferromagnetic multi-level memory cell: Antiferromagnets (AFs) are remarkable magnetically ordered materials that due\nto the absence of a net magnetic moment do not generate dipolar fields and are\ninsensitive to external magnetic field perturbations. However, it has been\nnotoriously difficult to control antiferromagnetic moments by any practical\nmeans suitable for device applications. This has left AFs over their hundred\nyears history virtually unexploited and only poorly explored, in striking\ncontrast to the thousands of years of fascination and utility of\nferromagnetism. Very recently it has been predicted and experimentally\nconfirmed that relativistic spin-orbit torques can provide the means for\nefficient electrical control of an AF. Here we place the emerging field of\nantiferromagnetic spintronics on the map of non-volatile solid state memory\ntechnologies. We demonstrate the complete write/store/read functionality in an\nantiferromagnetic CuMnAs bit cell embedded in a standard printed circuit board\ncommunicating with a computer via a USB interface. We show that the\nelementary-shape bit cells fabricated from a single-layer AF are electrically\nwritten on timescales ranging from milliseconds to nanoseconds and we\ndemonstrate their deterministic multi-level switching. The multi-level cell\ncharacteristics, reflecting series of reproducible, electrically controlled\ndomain reconfigurations, allow us to integrate memory and signal counter\nfunctionalities within the bit cell."
    },
    {
        "anchor": "Predicting Failure: Acoustic Emission of Berlinite under Compression: Acoustic emission has been measured and statistical characteristics have been\nanalyzed during the stress-induced collapse of porous berlinite, AlPO4,\ncontaining up to 50 vol% porosity. Stress collapse occurs in a series of\nindividual events (avalanches), and each avalanche leads to a jerk in sample\ncompression with corresponding acoustic emission (AE) signals. The distribution\nof AE avalanche energies can be approximately described by a power law over a\nlarge stress interval. We observed several collapse mechanisms whereby less\nporous minerals show the superposition of independent jerks, which were not\nrelated to the major collapse at the failure stress. In highly porous berlinite\n(40% and 50%) an increase of the energy emission occurred near the failure\npoint. In contrast, the less porous samples did not show such an increase in\nenergy emission. Instead, in the near vicinity of the main failure point they\nshowed a reduction in the energy exponent to ~ 1.4, which is consistent with\nthe value reported for compressed porous systems displaying critical behavior.\nThis indicated that a critical avalanche regime with a lack of precursor events\noccurs. In this case, all preceding large events were false alarms and\nunrelated to the main failure event. Our results identify a method to use\npico-seismicity detection of foreshocks to warn of mine collapse before the\nmain failure collapse occurs, which can be applied for highly porous materials\nonly.",
        "positive": "Probing the uniaxial strain-dependent valley drift and Berry curvature\n  in monolayer MoSi$_2$N$_4$: We use ab initio calculations and theoretical analysis to investigate the\ninfluence of in-plane strain field on valley drifts and Berry curvatures in the\nmonolayer MoSi$_2$N$_4$, a prototypical septuple atomic layered two-dimensional\nmaterial. The low energy electron and hole valleys drift far off the K/K' point\nunder uniaxial strains. The direction and strength of valley drift strongly\ndepend on the nature of the charge carrier and uniaxial strain with a more\nsubstantial response along the zigzag path. Our findings are governed by the\ninterplay between microscopic orbital contribution and symmetry lowering. The\nchanging geometric properties of Bloch states affect the Berry curvatures and\ncircular dichroism. Specifically, Berry curvature dipole is significantly\nenhanced under the tensile strain along armchair and zigzag directions.\nMeanwhile, the particle-hole asymmetry arising from non-equivalent electron and\nhole valley drifts relax the selection rules, thus reducing the degree of\ncircular polarization up to ~0.98. Therefore, strain engineering of valley\nphysics in the monolayer MoSi$_2$N$_4$ is of prime importance for\nvalleytronics."
    },
    {
        "anchor": "A DFT-based Molecular Transport Implementation in ADF/BAND: We present a novel implementation of the first-principles approach to\nmolecular charge transport using the non-equilibrium Green's function formalism\nin combination with the ADF/BAND periodic band-structure DFT code, together\nwith results for several example systems. As a proof of concept, we first\ndiscuss transport calculations on 1D chains of Li and Al atoms. We then present\na detailed study of BDT and archetypal molecular wires from the OPE-family,\nsandwiched between 3D Au contacts, comparing well with results from the\nliterature. Our implementation further allows us to make a comparison of 3D\ncontacts with and without periodic boundary conditions, the latter being\nparticularly useful for modeling the needle-shaped contacts used in\nbreak-junction experiments.",
        "positive": "Spin-Reorientation and Weak Ferromagnetism in Antiferromagnetic\n  TbMn_{0.5}Fe_{0.5}O_3: Orthorhombic single crystals of TbMn0.5Fe0.5O3 are found to exhibit\nspin-reorientation, magnetization reversal and weak ferromagnetism. Strong\nanisotropy effects are evident in the temperature dependent magnetization\nmeasurements along the three crystallographic axes a, b and c. A broad magnetic\ntransition is visible at T_N (Fe/Mn) = 286 K due to paramagnetic to AxGyCz\nordering. A sharp transition is observed at T_SR (Fe/Mn) = 28 K, which is\npronounced along c axis in the form of a sharp jump in magnetization where the\nspins reorient to GxAyFz configuration. The negative magnetization observed\nbelow TSR Fe/Mn along c axis is explained in terms of domain wall pinning. A\ncomponent of weak ferromagnetism is observed in field-scans along c-axis but\nbelow 28 K. Field-induced steps-like transitions are observed in hysteresis\nmeasurement along b axis below 28 K. It is noted that no sign of Tb-order is\ndiscernible down to 2 K. TbMn0.5Fe0.5O3 could be highlighted as a potential\ncandidate to evaluate its magneto-dielectric effects across the magnetic\ntransitions."
    },
    {
        "anchor": "The Electrical and Spin Properties of Monolayer and Bilayer Janus HfSSe\n  under Vertical Electrical Field: In this paper, the electrical and spin properties of mono- and bilayer HfSSe\nin the presence of a vertical electric field are studied. The density\nfunctional theory is used to investigate their properties. Fifteen different\nstacking orders of bilayer HfSSe are considered. The mono- and bilayer\ndemonstrate an indirect bandgap, whereas the bandgap of bilayer can be\neffectively controlled by electric field. While the bandgap of bilayer closes\nat large electric fields and a semiconductor to metal transition occurs, the\neffect of a normal electric field on the bandgap of the monolayer HfSSe is\nquite weak. Spin-orbit coupling causes band splitting in the valence band and\nRashba spin splitting in the conduction band of both mono- and bilayer\nstructures. The band splitting in the valence band of the bilayer is smaller\nthan a monolayer, however, the vertical electric field increases the band\nsplitting in bilayer one. The stacking configurations without mirror symmetry\nexhibit Rashba spin splitting which is enhanced with the electric field.",
        "positive": "Microstructure-property prediction of a Ni-based superalloy: A combined\n  phase-field and finite element modelling approach: Multiscale modelling is a new paradigm that has emerged in recent times to\nstudy the well-known problem of the process-structure-property relationship in\nthe area of materials science and engineering. For obtaining the desired\nperformance for materials of strategic importance, such as superalloys, it is\nessential to bridge different length and time scales in order to navigate the\nentire design space. In the present study, we develop a physics-based model for\na Ni-based superalloy where the microstructures simulated using a phase-field\nmodel serve as input to finite-element computations. We examine the alloy's\nmicrostructure evolution and effective elastic properties quantitatively via\nphase-field and finite element methods integrated with CALPHAD database, by\nvarying composition and aging temperature. The phase-field simulations provide\nus with an insight into the different regimes of microstructure evolution. The\nfinite element analysis uncovers the relation of effective elastic properties\nwith several system parameters."
    },
    {
        "anchor": "Anticorrelated Photoluminescence and Free Charge Generation Proves\n  Field-Assisted Exciton Dissociation in Low-Offset PM6:Y5 Organic Solar Cells: Understanding the origin of inefficient photocurrent generation in organic\nsolar cells with low energy offset remains key to realizing high performance\ndonor-acceptor systems. Here, we probe the origin of field-dependent free\ncharge generation and photoluminescence in non-fullerene acceptor (NFA) based\norganic solar cells using the polymer PM6 and NFA Y5 - a non-halogenated\nsibling to Y6, with a smaller energetic offset to PM6. By performing\ntime-delayed collection field (TDCF) measurements on a variety of samples with\ndifferent electron transport layers and active layer thickness, we show that\nthe fill factor and photocurrent are limited by field-dependent free charge\ngeneration in the bulk of the blend. We also introduce a new method of TDCF\ncalled m-TDCF to prove the absence of artefacts from non-geminate recombination\nof photogenerated- and dark charge carriers near the electrodes. We then\ncorrelate free charge generation with steady state photoluminescence intensity,\nand find perfect anticorrelation between these two properties. Through this, we\nconclude that photocurrent generation in this low offset system is entirely\ncontrolled by the field dependent exciton dissociation into charge transfer\nstates.",
        "positive": "Photoconductivity and photo-detection response of multiferroic bismuth\n  iron oxide: We report visible light detection with in-plane BiFeO3 (BFO) thin films grown\non pre-patterned inter-digital electrodes. In-plane configured BFO film\ndisplayed photocurrents with a 40:1 photo-to-dark-current ratio and improved\nphoto-sensing ability for >15000 s (4 hrs) under small bias voltage (42V).\nNearly sixty percent of the photo-induced charge carriers decay in 1.0 s and\nfollow a double-exponential decay model. At 373 K the effect of light does not\nsignificantly increase the dark current, probably due to reduced mobility.\nSub-bandgap weak monochromatic light (1 mw/cm2) shows one fold increase in\nphoto-charge carriers."
    },
    {
        "anchor": "Lattice dynamics and thermodynamics of bcc vanadium at high pressures: We investigate the lattice dynamics and thermodynamics of nonmagnetic bcc\nvanadium as a function of temperature and pressure, using the first principles\nlinear response linear-muffin-tin-orbital method. The calculated phonon density\nof states (DOS) show strong temperature dependence, different from inelastic\nneutron scattering measurements where the phonon DOS show little change from\nroom temperature up to 1273 K. We obtain the Helmholtz free energy including\nboth electronic and phonon contributions and calculate various equation of\nstate properties such as the bulk modulus and the thermal expansion\ncoefficient. A detailed comparison has been made with available experimental\nmeasurements.",
        "positive": "Phase diagram of Pb(Zr,Ti)O3 solid solutions from first principles: A first-principles-derived scheme, that incorporates ferroelectric and\nantiferrodistortive degrees of freedom, is developed to study\nfinite-temperature properties of PbZr1-xTixO3 solid solutions near its\nmorphotropic phase boundary. The use of this numerical technique (i) resolves\ncontroversies about the monoclinic ground-state for some Ti compositions, (ii)\nleads to the discovery of an overlooked phase, and (iii) yields three\nmultiphase points, that are each associated with four phases. Additional\nneutron diffraction measurements strongly support some of these predictions."
    },
    {
        "anchor": "Improving the doping efficiency of Al in 4H-SiC by co-doping group-IVB\n  elements: The p-type doping efficiency of 4H silicon carbide (4H-SiC) is rather low due\nto the large ionization energies of p-type dopants. Such an issue impedes the\nexploration of the full advantage of 4H-SiC for semiconductor devices. In this\nletter, we show that co-doping group-IVB elements effectively decreases the\nionization energy of the most widely used p-type dopant, i. e., aluminum (Al),\nthrough the Coulomb repulsion between the energy levels of group-IVB elements\nand that of Al in 4H-SiC. Among group-IVB elements Ti has the most prominent\neffectiveness. Ti decreases the ionization energy of Al by nearly 50%, leading\nto a value as low as ~ 0.13 eV. As a result, the ionization rate of Al with Ti\nco-doping is up to ~ 5 times larger than that without co-doping at room\ntemperature when the doping concentration is up to 1018 cm-3. This work may\nencourage the experimental co-doping of group-IB elements such as Ti and Al to\nsignificantly improve the p-type doping efficiency of 4H-SiC.",
        "positive": "Broken inversion symmetry in van der Waals topological ferromagnetic\n  metal iron germanium telluride: Inversion symmetry breaking is critical for many quantum effects and\nfundamental for spin-orbit torque, which is crucial for next-generation\nspintronics. Recently, a novel type of gigantic intrinsic spin-orbit torque has\nbeen established in the topological van-der-Waals (vdW) magnet iron germanium\ntelluride. However, it remains a puzzle because no clear evidence exists for\ninterlayer inversion symmetry breaking. Here, we report the definitive evidence\nof broken inversion symmetry in iron germanium telluride directly measured by\nthe second harmonic generation (SHG) technique. Our data show that the crystal\nsymmetry reduces from centrosymmetric P63/mmc to noncentrosymmetric polar P3m1\nspace group, giving the three-fold SHG pattern with dominant out-of-plane\npolarization. Additionally, the SHG response evolves from an isotropic pattern\nto a sharp three-fold symmetry upon increasing Fe deficiency, mainly due to the\ntransition from random defects to ordered Fe vacancies. Such SHG response is\nrobust against temperature, ensuring unaltered crystalline symmetries above and\nbelow the ferromagnetic transition temperature. These findings add crucial new\ninformation to our understanding of this interesting vdW metal, iron germanium\ntelluride: band topology, intrinsic spin-orbit torque and topological vdW polar\nmetal states."
    },
    {
        "anchor": "Plastic forming of metals at the nanoscale: interdiffusion-induced\n  bending of bimetallic nanowhiskers: Controlled plastic forming of nanoscale metallic objects by applying\nmechanical load is a challenge, since defect-free nanocrystals usually yield at\nnear theoretical shear strength, followed by an uncontrolled catastrophic\nfailure. Herein, instead of mechanical load, we utilize chemical stress from\nimbalanced interdiffusion to manipulate the shape of nanowhiskers. Bimetallic\nAu-Fe nanowhiskers with an ultra-high bending strength were synthesized\nemploying the molecular beam epitaxy technique. The one-sided Fe coating on the\ndefect-free, single-crystalline Au nanowhisker exhibited both single- and\npoly-crystalline regions. Annealing the bimetallic nanowhiskers at elevated\ntemperatures led to gradual change of curvature and irreversible bending, which\nis attributed to the grain boundary Kirkendall effect during the diffusion of\nAu along the grain boundaries in the Fe layer. The results of this study\ndemonstrate a high potential of chemical interdiffusion in the controlled\nplastic forming of ultra-strong metal nanostructures.",
        "positive": "Magnetism in Metastable and Annealed Compositionally Complex Alloys: Compositionally complex materials (CCMs) present a potential paradigm shift\nin the design of magnetic materials. These alloys exhibit long-range structural\norder coupled with limited or no chemical order. As a result, extreme local\nenvironments exist with a large opposing magnetic energy term, which can\nmanifest large changes in the magnetic behavior. In the current work, the\nmagnetic properties of (Cr, Mn, Fe, Ni) alloys are presented. These materials\nwere prepared by room-temperature combinatorial sputtering, resulting in a\nrange of compositions with a single BCC structural phase and no chemical\nordering. The combinatorial growth technique allows CCMs to be prepared outside\nof their thermodynamically stable phase, enabling the exploration of otherwise\ninaccessible order. The mixed ferromagnetic and antiferromagnetic interactions\nin these alloys causes frustrated magnetic behavior, which results in an\nextremely low coercivity (<1 mT), which increases rapidly at 50 K. At low\ntemperatures, the coercivity achieves values of nearly 500 mT, which is\ncomparable to some high-anisotropy magnetic materials. Commensurate with the\ndivergent coercivity is an atypical drop in the temperature dependent\nmagnetization. These effects are explained by a mixed magnetic phase model,\nconsisting of ferro-, antiferro , and frustrated magnetic regions, and are\nrationalized by simulations. A machine-learning algorithm is employed to\nvisualize the parameter space and inform the development of subsequent\ncompositions. Annealing the samples at 600 {\\deg}C orders the sample, more-than\ndoubling the Curie temperature and increasing the saturation magnetization by\nas much as 5x. Simultaneously, the large coercivities are suppressed, resulting\nin magnetic behavior that is largely temperature independent over a range of\n350 K."
    },
    {
        "anchor": "Defect induced rigidity enhancement in layered semiconductors: We discuss the mechanism responsible for the observed improvement in the\nstructural properties of In doped GaSe, a layered material of great current\ninterest. Formation energy calculations show that by tuning the Fermi energy,\nIn can substitute for Ga or can go as an interstitial charged\ndefect$(\\text{In}_{\\text{i}}^{\\text{3+}})$. We find that\n$\\text{In}_{\\text{i}}^{\\text{3+}}$ dramatically increases the shear stiffness\nof GaSe, explaining the observed enhancement in the rigidity of In doped\np-GaSe. The mechanism responsible for rigidity enhancement discussed here is\nquite general and applicable to a large class of layered solids with weak\ninterlayer bonding.",
        "positive": "In-situ real-time evolution of intrinsic stresses and microstructure\n  during growth of cathodic arc deposited (Al,Ti)N coatings: The residual stress plays a vital role in determination of the device\nperformance that uses thin films coating and thus the accurate determination of\nstress and its optimization with process parameters is an ongoing research work\nfor many decades. In line with this, the microscopic origin of the stress at\nthe atomic scale and its development during the thin film deposition is a\nmatter of major scientific interests. The development of stress is a complex\nphenomenon and has a complex dependence to process parameters, film\nmicrostructure and its morphology. In this work, by utilizing a custom-designed\ncathodic arc deposition system and synchrotron radiation based 2D x-ray\ndiffraction (XRD) technique, we determine the real-time evolution of stress,\ncrystallite sizes and their preferential orientations of\nAluminum-Titanium-Nitride (AlxTi1-xN) films with varied Al-content (x=0.0,\n0.25, 0.50, and 0.67) on Si-100 substrate. The energies of incoming ions and\nhence stress in the films is tuned by applying different direct current\nsubstrate bias (Vs = floating potential, -20, -40, -60, -80, and -100 V). The\ninstantaneous stress is evaluated by the well-known d vs. sin2{\\psi} technique,\nwhile crystallite sizes are determined by analyzing line profiles of x-ray\ndiffractograms. The evolution of stress and crystallite sizes are modelled with\nmultiple numerical models from which kinetic parameters associated with the\nthin film depositions are extracted. The ex-situ microstructure\ncharacterizations of AlxTi1-xN coatings are carried out by scanning electron\nmicroscopy (SEM) and transmission electron microscopy (TEM). The formation of\nex-situ microstructure of the films is discussed considering the results\nobtained from in-situ XRD data. Finally, we demonstrate that the method\nutilized here is a powerful approach towards estimation of the fracture\ntoughness of thin film coatings."
    },
    {
        "anchor": "Prediction of first-order martensitic transitions in strained epitaxial\n  films: Coherent epitaxial growth allows to produce crystalline films with strained\nstructures which are unstable in the bulk. Thereby, the relationship between\nthe lattice parameters of the overlayer in the interface plane, $(a,b)$, and\nits minimum-energy out-of-plane lattice parameter, $c_{\\text{min}}(a,b)$, need\nnot be continuous. This general statement is proven by examples of total energy\ncalculations. As a consequence, $c_{\\text{min}}$, which is determined by the\nchoice of the substrate, and $c_{\\text{min}}$-dependent intrinsic properties of\nthe overlayer cannot always be tuned in a continuous way as one may aim to do\nby means of strained epitaxy. Employing the model of the epitaxial Bain path we\npredict that such discontinuities occur in films of the elements V, Nb, Ru, La,\nOs, and Ir. The abrupt change of $c_{\\text{min}}$ can be exploited to switch\nproperties specific to the overlayer material. This is demonstrated for the\nexample of the superconducting critical temperature of a V film which we\npredict to jump by 20% at a discontinuity of $c_{\\text{min}}$",
        "positive": "Spin-correlations and magnetic structure in an Fe monolayer on 5d\n  transition metal surfaces: We present a detailed first principles study on the magnetic structure of an\nFe monolayer on different surfaces of 5d transition metals. We use the\nspin-cluster expansion technique to obtain parameters of a spin model, and\npredict the possible magnetic ground state of the studied systems by employing\nthe mean field approach and in certain cases by spin dynamics calculations. We\npoint out that the number of shells considered for the isotropic exchange\ninteractions plays a crucial role in the determination of the magnetic ground\nstate. In the case of Ta substrate we demonstrate that the out-of-plane\nrelaxation of the Fe monolayer causes a transition from ferromagnetic to\nantiferromagnetic ground state. We examine the relative magnitude of nearest\nneighbour Dzyaloshinskii-Moriya (D) and isotropic (J) exchange interactions in\norder to get insight into the nature of magnetic pattern formations. For the\nFe/Os(0001) system we calculate a very large D/J ratio, correspondingly, a spin\nspiral ground state. We find that, mainly through the leading isotropic\nexchange and Dzyaloshinskii-Moriya interactions, the inward layer relaxation\nsubstantially influences the magnetic ordering of the Fe monolayer. For the\nFe/Re(0001) system characterized by large antiferromagnetic interactions we\nalso determine the chirality of the $120^{\\circ}$ N\\'eel-type ground state."
    },
    {
        "anchor": "Coherent Phonon Coupling to Individual Bloch States in Photoexcited\n  Bismuth: We investigate the temporal evolution of the electronic states at the bismuth\n(111) surface by means of time and angle resolved photoelectron spectroscopy.\nThe binding energy of bulk-like bands oscillates with the frequency of the\n$A_{1g}$ phonon mode whereas surface states are insensitive to the coherent\ndisplacement of the lattice. A strong dependence of the oscillation amplitude\non the electronic wavevector is correctly reproduced by \\textit{ab initio}\ncalculations of electron-phonon coupling. Besides these oscillations, all the\nelectronic states also display a photoinduced shift towards higher binding\nenergy whose dynamics follows the evolution of the electronic temperature.",
        "positive": "Single crystal growth and anisotropic magnetic properties of\n  Li$_2$Sr[Li$_{1-x}$Fe$_x$N]$_2$: Up to now, investigation of physical properties of ternary and higher\nnitridometalates was severely hampered by challenges concerning phase purity\nand crystal size. Employing a modified lithium flux technique, we are now able\nto prepare sufficiently large single crystals of the highly air and moisture\nsensitive nitridoferrate $\\rm Li_2Sr[Li_{1-x}Fe_xN]_2$ for anisotropic\nmagnetization measurements. The magnetic properties are most remarkable: large\nanisotropy and coercivity fields of 7 Tesla at $T = 2$ K indicate a significant\norbital contribution to the magnetic moment of iron. Altogether, the novel\ngrowth method opens a route towards interesting phases in the comparatively\nrecent research field of nitridometalates and should be applicable to various\nother materials."
    },
    {
        "anchor": "Best practices for the application of temperature- and\n  illumination-dependent current density-voltage $J$($V$,$T$,$i$) and\n  electron-beam induced current EBIC to novel thin film solar cells: As the photovoltaic community accelerates the development of new absorber\ncandidate materials towards high-performing PV devices, it is essential to\nfollow best practices and leverage deeper characterization tools. We have\nidentified temperature- and illumination-dependent current density-voltage\n$J$($V$,$T$,$i$) and electron-beam induced current (EBIC) measurements as two\npowerful PV device characterization techniques to evaluate the potential of\nnovel absorber candidate materials. Herein, we focus on the experimental\nmethods and best practices for applying $J$($V$,$T$,$i$) and EBIC, addressing\nparticular challenges in sample preparation and mounting. We demonstrate these\non the example of tin monosulfide, a promising PV absorber candidate material\nthat shares characteristics of many novel thin-film PV absorbers: mechanically\nsoft, polycrystalline, and used in heterojunction thin-film PV devices.",
        "positive": "Condensation and growth of Kirkendall voids in intermetallic compounds: A model for the simulation of Kirkendall voiding in metallic materials is\npresented based on vacancy diffusion, elastic-plastic and rate-dependent\ndeformation of spherical voids. Starting with a phenomenological explanation of\nthe Kirkendall effect we briefly discuss the consequences on the reliability of\nmicroelectronics. A constitutive model for void nucleation and growth is\npresented, which can be used to predict the temporal development of voids in\nsolder joints during thermal cycling. We end with exemplary numerical studies\nand discuss the potential of the results for the failure analysis of joining\nconnections."
    },
    {
        "anchor": "Local structure and defect segregation on the tilt grain boundaries in\n  silicon: We present the results of atomistic and ab initio simulation of several\ndifferent tilt grain boundaries (GB) in silicon. The boundary structures\nobtained with genetic algorithm turned out to have no coordination defects,\ni.e. all silicon atoms restored their tetrahedral coordination during the\nstructure optimisation. That concerns previously known symmetric {\\Sigma} 5\n(130), {\\Sigma} 3 (211) and {\\Sigma} 29 (520) boundaries as well as previously\nunknown asymmetric {\\Sigma} 9 (-255)/(-211), {\\Sigma} 3 (-255)/(211) and\n{\\Sigma} 13 (790)/(3 11 0) structures. We have performed an extensive study of\ndefect segregation on the boundaries, including neutral vacancy and carbon,\nphosphorus and boron impurities. A clear correlation between the segregation\nenergy of the defect and local geometry of the boundary site where the defect\nis segregated has been revealed. We suggest a simple purely geometric model for\nevaluation of approximate segregation energies of the listed defects.",
        "positive": "Liquid crystal anchoring transitions on aligning substrates processed by\n  plasma beam: We observe a sequence of the anchoring transitions in nematic liquid crystals\n(NLC) sandwiched between the hydrophobic polyimide substrates treated with the\nplasma beam. There is a pronounced continuous transition from homeotropic to\nlow tilted (nearly planar) alignment with the easy axis parallel to the\nincidence plane of the plasma beam (the zenithal transition) that takes place\nas the exposure dose increases. In NLC with positive dielectric anisotropy, a\nfurther increase in the exposure dose results in in-plane reorientation of the\neasy axis by 90 degrees (the azimuthal transition). This transition occurs\nthrough the two-fold degenerated alignment characteristic for the second order\nanchoring transitions. In contrast to critical behavior of anchoring, the\ncontact angle of NLC and water on the treated substrates monotonically declines\nwith the exposure dose. It follows that the surface concentration of\nhydrophobic chains decreases continuously. The anchoring transitions under\nconsideration are qualitatively interpreted by using a simple phenomenological\nmodel of competing easy axes which is studied by analyzing anchoring diagrams\nof the generalized polar and non-polar anchoring models."
    },
    {
        "anchor": "Honeycomb Layered Oxides With Silver Atom Bilayers and Emergence of\n  Non-Abelian SU(2) Interactions: Honeycomb layered oxides with monovalent or divalent, monolayered cationic\nlattices generally exhibit myriad crystalline features encompassing rich\nelectrochemistry, geometries and disorders, which particularly places them as\nattractive material candidates for next-generation energy storage applications.\nHerein, we report global honeycomb layered oxide compositions, ${\\rm\nAg_2}M_2{\\rm TeO_6}$ ($M = \\rm Ni, Mg, \\textit{etc}.$) exhibiting $\\rm Ag$ atom\nbilayers with sub-valent states within Ag-rich crystalline domains of ${\\rm\nAg_6}M_2{\\rm TeO_6}$ and $\\rm Ag$-deficient domains of ${\\rm Ag}_{2 - x}\\rm\nNi_2TeO_6$ ($0 < x < 2$). The $\\rm Ag$-rich material characterised by\naberration-corrected transmission electron microscopy reveals local atomic\nstructural disorders characterised by aperiodic stacking and incoherency in the\nbilayer arrangement of $\\rm Ag$ atoms. Meanwhile, the global material not only\ndisplays high ionic conductivity, but also manifests oxygen-hole\nelectrochemistry during silver-ion extraction. Within the $\\rm Ag$-rich\ndomains, the bilayered structure, argentophilic interactions therein and the\nexpected $\\rm Ag$ sub-valent states ($1/2+, 2/3+, \\textit{etc}.$) are\ntheoretically understood via spontaneous symmetry breaking of\nSU($2$)$\\times$U($1$) gauge symmetry interactions amongst $3$ degenerate\nmass-less chiral fermion states, justified by electron occupancy of silver\n$4d_{z^2}$ and $5s$ orbitals on a bifurcated honeycomb lattice. This implies\nthat bilayered frameworks have research applications that go beyond the\nconfines of energy storage.",
        "positive": "Bayesian inference of composition-dependent phase diagrams: Phase diagrams serve as a highly informative tool for materials design,\nencapsulating information about the phases that a material can manifest under\nspecific conditions. In this work, we develop a method in which Bayesian\ninference is employed to combine thermodynamic data from molecular dynamics\n(MD), melting point simulations, and phonon calculations, process these data,\nand yield a temperature-concentration phase diagram. The employed Bayesian\nframework yields us not only the free energies of different phases as functions\nof temperature and concentration but also the uncertainties of these free\nenergies originating from statistical errors inherent to finite-length MD\ntrajectories. Furthermore, it extrapolates the results of the finite-atom\ncalculations to the infinite-atom limit and facilitates the choice of\ntemperature, chemical potentials, and the number of atoms conducting the next\nsimulation with which will be the most efficient in reducing the uncertainty of\nthe phase diagram. The developed algorithm was successfully tested on two\nbinary systems, Ge-Si and K-Na, in the full range of concentrations and\ntemperatures."
    },
    {
        "anchor": "Lasing in the Space Charge-Limited Current Regime: We introduce an analytical model for ideal organic laser diodes based on the\nargument that their intrinsic active layers necessitate operation in the\nbipolar space charge-limited current regime. Expressions for the threshold\ncurrent and voltage agree well with drift-diffusion modeling of complete p-i-n\ndevices and an analytical bound is established for laser operation in the\npresence of annihilation and excited-state absorption losses. These results\nestablish a foundation for the development of organic laser diode technology.",
        "positive": "Assessing the performance of the Random Phase Approximation for exchange\n  and superexchange coupling constants in magnetic crystalline solids: The Random Phase Approximation (RPA) for total energies has previously been\nshown to provide a qualitatively correct description of static correlation in\nmolecular systems, where density functional theory (DFT) with local functionals\nare bound to fail. This immediately poses the question of whether the RPA is\nalso able to capture the correct physics of strongly correlated solids such as\nMott insulators. Due to strong electron localization, magnetic interactions in\nsuch systems are dominated by superexchange, which in the simplest picture can\nbe regarded as the analogue of static correlation for molecules. In the present\nwork we investigate the performance of the RPA for evaluating both\nsuperexchange and direct exchange interactions in the magnetic solids NiO, MnO,\nNa3Cu2SbO6, Sr2CuO3, Sr2CuTeO6, and a monolayer of CrI3, which are chosen to\nrepresent a broad variety of magnetic interactions. It is found that the RPA\ncan accurately correct the large errors introduced by Hartree-Fock -\nindependent of the input orbitals used for the perturbative expansion. However,\nin most cases, accuracies similar to RPA can be obtained with DFT+U, which is\nsignificantly simpler from a computational point of view."
    },
    {
        "anchor": "Giant thermoelectric effect in Al2O3 magnetic tunnel junctions: Thermoelectric effects in magnetic nanostructures and the so-called spin\ncaloritronics are attracting much interest. Indeed it provides a new way to\ncontrol and manipulate spin currents which are key elements of spin-based\nelectronics. Here we report on giant magnetothermoelectric effect in Al2O3\nmagnetic tunnel junctions. The thermovoltage in this geometry can reach 1 mV.\nMoreover a magneto-thermovoltage effect could be measured with ratio similar to\nthe tunnel magnetoresistance ratio. The Seebeck coefficient can then be tuned\nby changing the relative magnetization orientation of the two magnetic layers\nin the tunnel junction. Therefore our experiments extend the range of\nspintronic devices application to thermoelectricity and provide a crucial piece\nof information for understanding the physics of thermal spin transport.",
        "positive": "Direct Evidence of Mg Incorporation Pathway in Vapor-Liquid-Solid Grown\n  p-type Nonpolar GaN Nanowires: Doping of III-nitride based compound semiconductor nanowires is still a\nchallenging issue to have a control over the dopant distribution in precise\nlocations of the nanowire optoelectronic devices. Knowledge of the dopant\nincorporation and its pathways in nanowires for such devices is limited by the\ngrowth methods. We report the direct evidence of incorporation pathway for Mg\ndopants in p-type nonpolar GaN nanowires grown via vapour-liquid-solid (VLS)\nmethod in a chemical vapour deposition technique for the first time. Mg\nincorporation is confirmed using X-ray photoelectron (XPS) and electron energy\nloss spectroscopic (EELS) measurements. Energy filtered transmission electron\nmicroscopic (EFTEM) studies are used for finding the Mg incorporation pathway\nin the GaN nanowire. Photoluminescence studies on Mg doped GaN nanowires along\nwith the electrical characterization on heterojunction formed between nanowires\nand n-Si confirm the activation of Mg atoms as p-type dopants in nonpolar GaN\nnanowires."
    },
    {
        "anchor": "Transport in Nanotubes: Effect of Remote Impurity Scattering: Theory of the remote Coulomb impurity scattering in single--wall carbon\nnanotubes is developed within one--electron approximation. Boltzmann equation\nis solved within drift--diffusion model to obtain the tube conductivity. The\nconductivity depends on the type of the nanotube bandstructure (metal or\nsemiconductor) and on the electron Fermi level. We found exponential dependence\nof the conductivity on the Fermi energy due to the Coulomb scattering rate has\na strong dependence on the momentum transfer. We calculate intra-- and\ninter--subband scattering rates and present general expressions for the\nconductivity. Numerical results, as well as obtained analytical expressions,\nshow that the degenerately doped semiconductor tubes may have very high\nmobility unless the doping level becomes too high and the inter--subband\ntransitions impede the electron transport.",
        "positive": "Kondo effect in metallic glasses with non-Fermi liquid behavior: By microalloying of Gd atoms with 4f electrons into CuZrAl or MgCuY glassy\nalloys, they display a variety of puzzling behaviors such as the characteristic\nof Kondo effect. The ground states of the Gd-alloyed systems are determined to\nhave non-Fermi-liquid characteristics which derive from the strong structural\ndisorder. The Kondo effect in these glassy alloys is attributed to the strong\nstructural disorder. The coexistence of the Kondo effect and strong structural\ndisorder has implications for the understanding the origin of the puzzling\nnon-Fermi-liquid behavior."
    },
    {
        "anchor": "Anharmonic phonon behavior via irreducible derivatives: self-consistent\n  perturbation theory and molecular dynamics: Cubic phonon interactions are now regularly computed from first principles,\nand the quartic interactions have begun to receive more attention. Given this\nrealistic anharmonic vibrational Hamiltonian, the classical phonon Green's\nfunction can be precisely measured using molecular dynamics, which can then be\nused to rigorously assess the range of validity for self-consistent\ndiagrammatic approaches in the classical limit. Here we use the bundled\nirreducible derivative approach to efficiently and precisely compute the cubic\nand quartic phonon interactions of CaF$_2$, systematically obtaining the\nvibrational Hamiltonian purely in terms of irreducible derivatives. non\nfrequency shifts and linewidths, We demonstrate that the 4-phonon sunset\ndiagram has an important contribution to the optical phonon linewidths beyond\n$T=500$ K. Reasonable results are obtained even at $T=900$ K when performing\nself-consistency using the 4-phonon loop diagram and evaluating the 3-phonon\nbubble and 4-phonon sunset diagrams post self-consistency. Further improvements\nare obtained by performing quasiparticle perturbation theory, where both the\n4-phonon loop and the real part of the 3-phonon bubble are employed during\nself-consistency. Our irreducible derivative approach to self-consistent\nperturbation theory is a robust tool for studying anharmonic phonons in both\nthe quantum and classical regimes.",
        "positive": "Directional massless Dirac fermions in a layered van der Waals material\n  with one-dimensional long-range order: Exotic properties in single or few layers of van der Waals materials carry\ngreat promise for applications in nanoscaled electronics, optoelectronics and\nflexible devices. The established, distinct examples include extremely high\nmobility and superior thermal conductivity in graphene, a large direct band gap\nin monolayer MoS2 and quantum spin Hall effect in WTe2 monolayer, etc. All\nthese exotic properties arise from the electron quantum confinement effect in\nthe two-dimensional limit. Here we report a novel phenomenon due to\none-dimensional (1D) confinement of carriers in a layered van der Waals\nmaterial NbSi0.45Te2 revealed by angle-resolved photoemission spectroscopy,\ni.e. directional massless Dirac fermions. The 1D behavior of the carriers is\ndirectly related to a stripe-like structural modulation with the long-range\ntranslational symmetry only along the stripe direction, as perceived by\nscanning tunneling microscopy experiment. The four-fold degenerated node of 1D\nDirac dispersion is essential and independent on band inversion, because of the\nprotection by nonsymmorphic symmetry of the stripe structure. Our study not\nonly provides a playground for investigating the striking properties of the\nessential directional massless Dirac fermions, but also introduces a unique\nmonomer with 1D long-range order for engineering nano-electronic devices based\non heterostructures of layered van der Waals materials."
    },
    {
        "anchor": "Holographic patterning of graphene-oxide films by light-driven reduction: We report on the patterning and reduction of graphene-oxide films by\nholographic lithography. Light reduction can be used to engineer low-cost\ngraphene-based devices by performing a local conversion of insulating oxide\ninto the conductive graphene. In this work, computer generated holograms have\nbeen exploited to realize complex graphene patterns in a single shot,\ndifferently from serial laser writing or mask-based photolithographic\nprocesses. The technique has been further improved by achieving speckle noise\nreduction: submicron and diffraction-limited features have been obtained. In\naddition we have also demonstrated that the gray-scale lithography capability\ncan be used to obtain different reduction levels in a single exposure.",
        "positive": "Electronic structure of 30\u00b0 twisted double bilayer graphene: In this paper, the electronic properties of 30{\\deg} twisted double bilayer\ngraphene, which loses the translational symmetry due to the incommensurate\ntwist angle, are studied by means of the tight-binding approximation. We\ndemonstrate the interlayer decoupling in the low-energy region from various\nelectronic properties, such as the density of states, effective band structure,\noptical conductivity and Landau level spectrum. However, at Q points, the\ninterlayer coupling results in the appearance of new Van Hove singularities in\nthe density of states, new peaks in the optical conductivity and importantly\nthe 12-fold-symmetry-like electronic states. The k-space tight-binding method\nis adopted to explain this phenomenon. The electronic states at Q points show\nthe charge distribution patterns more complex than the 30{\\deg} twisted bilayer\ngraphene due to the symmetry decrease. These phenomena appear also in the\n30{\\deg} twisted interface between graphene monolayer and AB stacked bilayer."
    },
    {
        "anchor": "Graphene buffer layer on Si-terminated SiC : a multi-minima energy\n  surface studied with an empirical interatomic potential: The atomistic structure of the graphene buffer layer on Si-terminated SiC is\nstudied using a modified environment-dependent interatomic potential (EDIP).\nThe investigation of equilibrium state by conjuguate gradients suffers from a\ncomplex multi-minima energy surface. A dedicated procedure is therefore\npresented to provide a suitable initial configuration on the way to the\nminimum. The result forms an hexagonal pattern with unsticked rods to release\nthe misfit with the surface. The structure presents an agreement with the\nglobal pattern obtained by experiments and even with the details of an ab\ninitio calculation.",
        "positive": "Dynamical properties of Au from tight-binding molecular-dynamics\n  simulations: We studied the dynamical properties of Au using our previously developed\ntight-binding method. Phonon-dispersion and density-of-states curves at T=0 K\nwere determined by computing the dynamical-matrix using a supercell approach.\nIn addition, we performed molecular-dynamics simulations at various\ntemperatures to obtain the temperature dependence of the lattice constant and\nof the atomic mean-square-displacement, as well as the phonon density-of-states\nand phonon-dispersion curves at finite temperature. We further tested the\ntransferability of the model to different atomic environments by simulating\nliquid gold. Whenever possible we compared these results to experimental\nvalues."
    },
    {
        "anchor": "Oxidising and carburising catalyst conditioning for the controlled\n  growth and transfer of large crystal monolayer hexagonal boron nitride: Hexagonal boron nitride (h-BN) is well-established as a requisite support,\nencapsulant and barrier for 2D material technologies, but also recently as an\nactive material for applications ranging from hyperbolic metasurfaces to room\ntemperature single-photon sources. Cost-effective, scalable and high quality\ngrowth techniques for h-BN layers are critically required. We utilise\nwidely-available iron foils for the catalytic chemical vapour deposition (CVD)\nof h BN and report on the significant role of bulk dissolved species in h-BN\nCVD, and specifically, the balance between dissolved oxygen and carbon. A\nsimple pre-growth conditioning step of the iron foils enables us to tailor an\nerror-tolerant scalable CVD process to give exceptionally large h-BN monolayer\ndomains. We also develop a facile method for the improved transfer of as-grown\nh-BN away from the iron surface by means of the controlled humidity oxidation\nand subsequent rapid etching of a thin interfacial iron oxide; thus, avoiding\nthe impurities from the bulk of the foil. We demonstrate wafer-scale (2 inch)\nproduction and utilise this h-BN as a protective layer for graphene towards\nintegrated (opto) electronic device fabrication.",
        "positive": "Thermodynamic consistency and fast dynamics in phase field crystal\n  modeling: A general formulation is presented to derive the equation of motion and to\ndemonstrate thermodynamic consistency for several classes of phase field models\nat once. It applies to models with a conserved phase field, describing either\nuniform or periodic stable states, and containing slow as well as fast\nthermodynamic variables. The approach is based on an entropy functional\nformalism previously developed in the context of phase field models for uniform\nstates [P. Galenko and D. Jou, Phys. Rev. E {\\bf 71}, 046125 (2005)] and thus\nallows to extend several properties of the latter to phase field models for\nperiodic states (phase field crystal models). In particular, it allows to\ndemonstrate the concept of thermodynamic consistency for phase field crystal\nmodels with fast dynamics."
    },
    {
        "anchor": "Enhanced Magnetism in Heterostructures with Transition-Metal\n  Dichalcogenide Monolayers: Two-dimensional materials and their heterostructures have opened up new\npossibilities for magnetism at the nanoscale. In this study, we utilize\nfirst-principles simulations to investigate the structural, electronic, and\nmagnetic properties of $\\textrm{Fe}/\\textrm{WSe}_2/\\textrm{Pt}$ systems\ncontaining pristine, defective, or doped $\\textrm{WSe}_2$ monolayers. The\nproximity effects of the ferromagnetic Fe layer are studied by considering\ndefective and vanadium-doped $\\textrm{WSe}_2$ monolayers. All heterostructures\nare found to be ferromagnetic, and the insertion of the transition-metal\ndichalcogenide results in a redistribution of spin orientation and an increased\ndensity of magnetic atoms due to the magnetized $\\textrm{WSe}_2$. There is an\nincrease in the overall total density of states at the Fermi level due to\n$\\textrm{WSe}_2$; however, the transition-metal dichalcogenide may lose its\ndistinct semiconducting properties due to the stronger than van der Waals\ncoupling. Spin-resolved electronic structure properties are linked to larger\nspin Seebeck coefficients found in heterostructures with $\\textrm{WSe}_2$\nmonolayers.",
        "positive": "Increasing informativity of the Thermally Stimulated Depolarization\n  method: Two modifications of the Thermally Stimulated Depolarization Current method\nare proposed to improve resolution and sensitivity of the method by connecting\neither a real capacitor, or an additional resistor in series with the sample.\nIt is shown experimentally that high sensitivity of the TSDC method with an air\ngap can be obtained, if the gap is substituted by the capacitor, while all\nadvantages of the method remain in force. It has been found that in one\nexperiment it is possible not only to measure the TSD current, but also to\nobtain data on the Thermally Stimulated Conductivity, if the properly selected\nadditional resistor is periodically switched on and off."
    },
    {
        "anchor": "Simple model for the spherically- and system-averaged pair density:\n  Results for two-electron atoms: As shown by Overhauser and others, accurate pair densities for the uniform\nelectron gas may be found by solving a two-electron scattering problem with an\neffective screened electron-electron repulsion. In this work we explore the\nextension of this approach to nonuniform systems, and we discuss its potential\nfor density functional theory. For the spherically- and system-averaged pair\ndensity of two-electron atoms we obtain very accurate short-range properties,\nincluding, for nuclear charge $Z\\ge 2$, ``on-top'' values (zero\nelectron-electron distance) essentially indistinguishable from those coming\nfrom precise variational wavefunctions. By means of a nonlinear adiabatic\nconnection that separates long- and short-range effects, we also obtain\nKohn-Sham correlation energies whose error is less than 4 mHartree, again for\n$Z\\ge 2$, and short-range-only correlation energies whose accuracy is one order\nof magnitude better.",
        "positive": "Manufacturing of Textured Bulk Fe-SmCo$_{5}$ Magnets by Severe Plastic\n  Deformation: Exchange-coupling between soft- and hard-magnetic phases plays an important\nrole in the engineering of novel magnetic materials. To achieve exchange\ncoupling, a two-phase microstructure is necessary. This interface effect is\nfurther enhanced if both phase dimensions are reduced to the nanometer scale.\nAt the same time, it is challenging to obtain large sample dimensions. In this\nstudy, powder blends and ball-milled powder blends of Fe-SmCo$_{5}$ are\nconsolidated and are deformed by high-pressure torsion (HPT), as this technique\nallows us to produce bulk magnetic materials of reasonable sizes. Additionally,\nthe effect of severe deformation by ball-milling and severe plastic deformation\nby HPT on exchange coupling in Fe-SmCo$_{5}$ composites is investigated. Due to\nthe applied shear deformation, it is possible to obtain a texture in both\nphases, resulting in an anisotropic magnetic behavior and an improved magnetic\nperformance."
    },
    {
        "anchor": "Interface kinetics in phase field models: isothermal transformations in\n  binary alloys and steps dynamics in molecular-beam-epitaxy: We present a unified description of interface kinetic effects in phase field\nmodels for isothermal transformations in binary alloys and steps dynamics in\nmolecular-beam-epitaxy. The phase field equations of motion incorporate a\nkinetic cross-coupling between the phase field and the concentration field.\nThis cross coupling generalizes the phenomenology of kinetic effects and was\nomitted until recently in classical phase field models. We derive general\nexpressions (independent of the details of the phase field model) for the\nkinetic coefficients within the corresponding macroscopic approach using a\nphysically motivated reduction procedure. The latter is equivalent to the\nso-called thin interface limit but is technically simpler. It involves the\ncalculation of the effective dissipation that can be ascribed to the interface\nin the phase field model. We discuss in details the possibility of a non\npositive definite matrix of kinetic coefficients, i.e. a negative effective\ninterface dissipation, although being in the range of stability of the\nunderlying phase field model. Numerically, we study the step-bunching\ninstability in molecular-beam-epitaxy due to the Ehrlich-Schwoebel effect,\npresent in our model due to the cross-coupling. Using the reduction procedure\nwe compare the results of the phase field simulations with the analytical\npredictions of the macroscopic approach.",
        "positive": "Novel Tin-based Gel Polymer Electrode and Its Use in Sodium-ion\n  Capacitor: We present a novel tin based flexible, gel polymer negative electrode for use\nin sodium-ion devices. The electrodes have been prepared by trapping tin\nmicro-particles in a porous electrolyte membrane formed by immersion\nprecipitation phase-inversion and soaking in a sodium-ion conducting liquid\nelectrolyte. The tin particles are the active electrode materials as well as\nelectron conductors, while the gel polymer enable efficient ion-transfer to the\ntin particles. The composite gel electrode and its performance in sodium-ion\ncapacitor has been analyzed using scanning electron microscopy. x-ray\ndiffraction, cyclic voltammetry and galvanostatic charge-discharge. The\nspecific capacity of the capacitor shows an initial increase, up to 175\ncharge-discharge cycles. This increase has been explained by the increase in\nsurface area of tin due to disintegration of the larger particles upon repeated\ninsertion/de-insertion of sodium. A high capacitance of 210 mAh g-1 at 1 A g-1\nhas also been measured."
    },
    {
        "anchor": "Atomic reconstruction and flat bands in strain engineered transition\n  metal dichalcogenide bilayer moir\u00e9 systems: Strain-induced lattice mismatch leads to moir\\'{e} patterns in homobilayer\ntransition metal dichalcogenides (TMDs). We investigate the structural and\nelectronic properties of such strained moir\\'{e} patterns in TMD homobilayers.\nThe moir\\'{e} patterns in strained TMDs consist of several stacking domains\nwhich are separated by tensile solitons. Relaxation of these systems\ndistributes the strain unevenly in the moir\\'{e} superlattice, with the maximum\nstrain energy concentrating at the highest energy stackings. The order\nparameter distribution shows the formation of aster topological defects at the\nsame sites. In contrast, twisted TMDs host shear solitons at the domain walls,\nand the order parameter distribution in these systems shows the formation of\nvortex defects. The strained moir\\'{e} systems also show the emergence of\nseveral well-separated flat bands at both the valence and conduction band\nedges, and we observe a significant reduction in the band gap. The flat bands\nin these strained moir\\'{e} superlattices provide platforms for studying the\nHubbard model on a triangular lattice as well as the ionic Hubbard model on a\nhoneycomb lattice. Furthermore, we study the localization of the wave functions\ncorresponding to these flat bands. The wave functions localize at different\nstackings compared to twisted TMDs, and our results are in excellent agreement\nwith recent spectroscopic experiments [1].",
        "positive": "Electronic structure of negatively curved graphene: We study the electronic structure of graphene in the presence of either\nsevenfolds or eightfolds by using a gauge field-theory model. The graphene\nsheet with topological defects is considered as a negative cone surface with\ninfinite Gaussian curvature at the center. The density of electronic states is\ncalculated for a single seven- and eightfold as well as for a pair of\nsevenfolds with different morphology. The density of states at the Fermi energy\nis found to be zero in all cases except two sevenfolds with translational\nfactor $M\\neq 0$."
    },
    {
        "anchor": "Designing Dirac points in two-dimensional lattices: We present a framework to elucidate the existence of accidental contacts of\nenergy bands, particularly those called Dirac points which are the point\ncontacts with linear energy dispersions in their vicinity. A generalized\nvon-Neumann-Wigner theorem we propose here gives the number of constraints on\nthe lattice necessary to have contacts without fine tuning of lattice\nparameters. By counting this number, one could quest for the candidate of Dirac\nsystems without solving the secular equation. The constraints can be provided\nby any kinds of symmetry present in the system. The theory also enables the\nanalytical determination of k-point having accidental contact by selectively\npicking up only the degenerate solution of the secular equation. By using these\nframeworks, we demonstrate that the Dirac points are feasible in various\ntwo-dimensional lattices, e.g. the anisotropic Kagome lattice under inversion\nsymmetry is found to have contacts over the whole lattice parameter space.\nSpin-dependent cases, such as the spin-density-wave state in LaOFeAs with\nreflection symmetry, are also dealt with in the present scheme.",
        "positive": "Activation Energy of Metastable Amorphous Ge2Sb2Te5 from Room\n  Temperature to Melt: Resistivity of metastable amorphous Ge2Sb2Te5 (GST) measured at device level\nshow an exponential decline with temperature matching with the steady-state\nthin-film resistivity measured at 858 K (melting temperature). This suggests\nthat the free carrier activation mechanisms form a continuum in a large\ntemperature scale (300 K - 858 K) and the metastable amorphous phase can be\ntreated as a super-cooled liquid. The effective activation energy calculated\nusing the resistivity versus temperature data follow a parabolic behavior, with\na room temperature value of 333 meV, peaking to ~377 meV at ~465 K and reaching\nzero at ~930 K, using a reference activation energy of 111 meV (3kBT/2) at\nmelt. Amorphous GST is expected to behave as a p-type semiconductor at Tmelt ~\n858 K and transitions from the semiconducting-liquid phase to the\nmetallic-liquid phase at ~ 930 K at equilibrium. The simultaneous Seebeck (S)\nand resistivity versus temperature measurements of amorphous-fcc mixed-phase\nGST thin-films show linear S-T trends that meet S = 0 at 0 K, consistent with\ndegenerate semiconductors, and the dS/dT and room temperature activation energy\nshow a linear correlation. The single-crystal fcc is calculated to have dS/dT =\n0.153 {\\mu}V/K for an activation energy of zero and a Fermi level 0.16 eV below\nthe valance band edge."
    },
    {
        "anchor": "Specific features of band structure and optical anisotropy of Cu2CdGeSe4\n  quaternary compounds: The complex theoretical and experimental studies of the band structure and\nthe optical functions of the Cu2CdGeSe4 quaternary crystals are reported. The\nbenchmark band structure calculations were performed using the first-principles\nmethods. As a result, the structural, electronic, optical and elastic\nproperties of Cu2CdGeSe4 were calculated in the general gradient approximation\n(GGA) and local density approximation (LDA). The calculated dielectric function\nand optical absorption spectra exhibit some anisotropic behavior. Detailed\nanalysis of the band energy dispersion and the effective space charge density\nhelped in establishing the origin of the band structure anisotropy. All\ncalculated properties are compared with the experimental data. An additional\ncomparison with a similar crystal of Cu2CdGeSe4 allowed to reveal the role\nplayed by the anions (S or Se) in formation of the optical properties of these\ntwo materials.",
        "positive": "Multi-principal element grain boundaries: Stabilizing nanocrystalline\n  grains with thick amorphous complexions: Amorphous complexions have recently been demonstrated to simultaneously\nenhance the ductility and stability of certain nanocrystalline alloys. In this\nstudy, three quinary alloys (Cu-Zr-Hf-Mo-Nb, Cu-Zr-Hf-Nb-Ti, and Cu-Zr-Hf-Mo-W)\nare studied to test the hypothesis that increasing the chemical complexity of\nthe grain boundaries will result in thicker amorphous complexions and further\nstabilize a nanocrystalline microstructure. Significant boundary segregation of\nZr, Nb, and Ti is observed in the Cu-Zr-Hf-Nb-Ti alloy, which creates a\nquaternary interfacial composition that limits average grain size to 63 nm even\nafter 1 week at ~97% of the melting temperature. This high level of thermal\nstability is attributed to the complex grain boundary chemistry and amorphous\nstructure resulting from multi-component segregation. High resolution\ntransmission electron microscopy reveals that the increased chemical complexity\nof the grain boundary region in the Cu-Zr-Hf-Nb-Ti alloy results in an average\namorphous complexion thickness of 2.44 nm, approximately 44% and 32% thicker\nthan amorphous complexions previously observed in Cu-Zr and Cu-Zr-Hf alloys."
    },
    {
        "anchor": "A transferable prediction model of molecular adsorption on metals based\n  on adsorbate and substrate properties: Surface adsorption is one of the fundamental processes in numerous fields,\nincluding catalysis, environment, energy and medicine. The development of an\nadsorption model which provides an effective prediction of binding energy in\nminutes has been a long term goal in surface and interface science. The\nsolution has been elusive as identifying the intrinsic determinants of the\nadsorption energy for various compositions, structures and environments is\nnon-trivial. We introduce a new and flexible model for predicting adsorption\nenergies to metal substrates. The model is based on easily computed, intrinsic\nproperties of the substrate and adsorbate. It is parameterised using machine\nlearning based on first-principles calculations of probe molecules (e.g.,\nH$_2$O, CO$_2$, O$_2$, N$_2$) adsorbed to a range of pure metal substrates. The\nmodel predicts the computed dissociative adsorption energy to metal surfaces\nwith a correlation coefficient of 0.93 and a mean absolute error of 0.77 eV for\nthe large database of molecular adsorption energies provided by\n\\textit{Catalysis-Hub.org} which have a range of 15 eV. As the model is based\non pre-computed quantities it provides near-instantaneous estimates of\nadsorption energies and it is sufficiently accurate to eliminate around 90\\% of\ncandidates in screening study of new adsorbates. The model, therefore,\nsignificantly enhances current efforts to identify new molecular coatings in\nmany applied research fields.",
        "positive": "Concentration-dependent atomic mobilities in FCC CoCrFeMnNi high-entropy\n  alloys: The diffusion kinetics in a CoCrFeMnNi high entropy alloy is investigated by\na combined radiotracer--interdiffusion experiment applied to a pseudo-binary\nCo$_{15}$Cr$_{20}$Fe$_{20}$Mn$_{20}$Ni$_{25}$ /\nCo$_{25}$Cr$_{20}$Fe$_{20}$Mn$_{20}$Ni$_{15}$ couple. As a result, the\ncomposition-dependent tracer diffusion coefficients of Co, Cr, Fe and Mn are\ndetermined. The elements are characterized by significantly different diffusion\nrates, with Mn being the fastest element and Co being the slowest one. The\nelements having originally equiatomic concentration through the diffusion\ncouple are found to reveal up-hill diffusion, especially Cr and Mn. The atomic\nmobility of Co seems to follow an S-shaped concentration dependence along the\ndiffusion path. The experimentally measured kinetic data are checked against\nthe existing CALPHAD-type databases. In order to ensure a consistent treatment\nof tracer and chemical diffusion a generalized symmetrized continuum approach\nfor multi-component interdiffusion is proposed. Both, tracer and chemical\ndiffusion concentration profiles are simulated and compared to the\nmeasurements. By using the measured tracer diffusion coefficients the chemical\nprofiles can be described, almost perfectly, including up-hill diffusion."
    },
    {
        "anchor": "Balancing orbital effects and onsite Coulomb repulsion through Na\n  modulations in NaxVO2: Vanadium oxides have been highly attractive for over half a century since the\ndiscovery of the metal insulator transition near room temperatures. Here NaxVO2\nis studied through a systematic comparison with other layered sodium metal\noxides with early 3d transition metals, first disclosing a unified evolution\npattern of Na density waves through in situ XRD analysis. Combining ab-initio\nsimulations and theoretical modelings, a sodium-modulated Peierls-like\ntransition mechanism is then proposed for the bonding formation of metal ion\ndimers. More importantly, the unique trimer structure in NaxVO2 is shown to be\nvery sensitive to the onsite Coulomb repulsion value, suggesting a delicate\nbalance between strong electronic correlations and orbital effects that can be\nprecisely modulated by both Na compositions and atomic stackings. This unveils\na unique opportunity to design strongly correlated materials with tailored\nelectronic transitions through electrochemical modulations and crystallographic\ndesigns, to elegantly balance various competition effects. We think the\nunderstanding will also help further elucidate complicated electronic behaviors\nin other vanadium oxide systems.",
        "positive": "Dissociation of high-pressure solid molecular hydrogen: Quantum Monte\n  Carlo and anharmonic vibrational study: A theoretical study is reported of the molecular-to-atomic transition in\nsolid hydrogen at high pressure. We use the diffusion quantum Monte Carlo\nmethod to calculate the static lattice energies of the competing phases and a\ndensity-functional-theory-based vibrational self-consistent field method to\ncalculate anharmonic vibrational properties. We find a small but significant\ncontribution to the vibrational energy from anharmonicity. A transition from\nthe molecular Cmca-12 direct to the atomic I4_1/amd phase is found at 374 GPa.\nThe vibrational contribution lowers the transition pressure by 91 GPa. The\ndissociation pressure is not very sensitive to the isotopic composition. Our\nresults suggest that quantum melting occurs at finite temperature."
    },
    {
        "anchor": "From Finite to Infinite Range Order via Annealing: The Causal\n  Architecture of Deformation Faulting in Annealed Close-Packed Crystals: We analyze solid-state phase transformations that occur in zinc-sulfide\ncrystals during annealing using a random deformation-faulting mechanism with a\nvery simple interaction between adjacent close-packed double layers. We show\nthat, through annealing, infinite-range structures emerge from initially\nshort-range crystal order. That is, widely separated layers carry structurally\nsignificant information and so layer stacking cannot be completely described by\nany finite-range Markov process. We compare our results to two experimental\ndiffraction spectra, finding excellent agreement.",
        "positive": "A three-stage magnetic phase transition revealed in ultrahigh-quality\n  van der Waals magnet CrSBr: van der Waals (vdW) magnets are receiving ever-growing attention nowadays due\nto their significance in both fundamental research on low-dimensional magnetism\nand potential applications in spintronic devices. High crystalline quality of\nvdW magnets is key for maintaining intrinsic magnetic and electronic\nproperties, especially when exfoliated down to the 2D limit. Here,\nultrahigh-quality air-stable vdW CrSBr crystals are synthesized using the\ndirect vapor-solid synthesis method. The high single crystallinity and spatial\nhomogeneity have been thoroughly evidenced at length scales from sub-mm to\natomic resolution by X-ray diffraction, second harmonic generation, and\nscanning transmission electron microscopy. More importantly, specific heat\nmeasurements of these ultrahigh quality CrSBr crystals show three thermodynamic\nanomalies at 185K, 156K, and 132K, revealing a stage-by-stage development of\nthe magnetic order upon cooling, which is also corroborated with the\nmagnetization and transport results. Our ultrahigh-quality CrSBr can further be\nexfoliated down to monolayers and bilayers easily, paving the way to integrate\nthem into heterostructures for spintronic and magneto-optoelectronic\napplications."
    },
    {
        "anchor": "Electronic structure of complex spd Hume-Rothery phases in\n  transition-metal aluminides: The discovery of quasicrystals phases and approximants in Al(rich)-Mn system\nhas revived the interest for complex aluminides containing transition-metal\natoms. On one hand, it is now accepted that the Hume-Rothery stabilization\nplays a crucial role. On the other hand, transition-metal atoms have also a\nvery important effect on their stability and their physical properties. In this\npaper, we review studies that unifies the classical Hume-Rothery stabilization\nfor sp electron phases with the virtual bound state model for transition-metal\natoms embedded in the aluminum matrix. These studies lead to a new theory for\n\\\"spd electron phases\\\". It is applied successfully to Al(Si)--transition-metal\nalloys and it gives a coherent picture of their stability and physical\nproperties. These works are based on first-principles calculations of the\nelectronic structure and simplified models, compared to experimental results. A\nmore detailed review article is published in Prog. Mater. Sci. 50 (2005) p.\n679-788.",
        "positive": "Wide range equation of state for fluid hydrogen within density\n  functional theory: Wide range equation of state (EOS) for liquid hydrogen is ultimately built by\ncombining two kinds of density functional theory (DFT) molecular dynamics\nsimulations, namely, first-principles molecular dynamics simulations and\norbital-free molecular dynamics simulations. Specially, the present\nintroduction of short cutoff radius pseudopotentials enables the hydrogen EOS\nto be available in the range $9.82\\times10^{-4}$ to $1.347\\times10^{3}$\ng/cm$^{3}$ and up to $5\\times10^{7}$ K. By comprehensively comparing with\nvarious attainable experimental and theoretical data, we derive the conclusion\nthat our DFT-EOS can be readily and reliably conducted to hydrodynamic\nsimulations of the inertial confinement fusion."
    },
    {
        "anchor": "Spin transport and spin dephasing in zinc oxide: The wide bandgap semiconductor ZnO is interesting for spintronic applications\nbecause of its small spin-orbit coupling implying a large spin coherence\nlength. Utilizing vertical spin valve devices with ferromagnetic electrodes\n(TiN/Co/ZnO/Ni/Au), we study the spin-polarized transport across ZnO in\nall-electrical experiments. The measured magnetoresistance agrees well with the\nprediction of a two spin channel model with spin-dependent interface\nresistance. Fitting the data yields spin diffusion lengths of 10.8nm (2K),\n10.7nm (10K), and 6.2nm (200K) in ZnO, corresponding to spin lifetimes of 2.6ns\n(2K), 2.0ns (10K), and 31ps (200K).",
        "positive": "Nitrogen doping of metallic single-walled carbon nanotubes: n-type\n  conduction and dipole scattering: The charge transport properties of individual, metallic nitrogen doped,\nsingle-walled carbon nanotubes are investigated. It is demonstrated that n-type\nconduction can be achieved by nitrogen doping. Evidence was obtained by\nappealing to electric-field effect measurements at ambient condition. The\nobserved temperature dependencies of the zero-bias conductance indicate a\ndisordered electron system with electric-dipole scattering, caused mainly by\nthe pyridine-type nitrogen atoms in the honeycomb lattice. These results\nillustrate the possibility of creating all-metallic molecular devices, in which\nthe charge carrier type can be controlled."
    },
    {
        "anchor": "Strain Coupled Domains in BaTiO3(111)-CoFeB Heterostructures: Domain pattern transfer from ferroelectric to ferromagnetic materials is a\ncritical step for the electric field control of magnetism and has the potential\nto provide new schemes for low-power data storage and computing devices. Here\nwe investigate domain coupling in BaTiO$_3$(111)/CoFeB heterostructures by\ndirect imaging in a wide-field Kerr microscope. The magnetic easy axis is found\nto locally change direction as a result of the underlying ferroelectric domains\nand their polarisation. By plotting the remanent magnetisation as a function of\nangle in the plane of the CoFeB layer, we find that the magnetic easy axes in\nadjacent domains are angled at 60$^\\circ$ or 120$^\\circ$, corresponding to the\nangle of rotation of the polarisation from one ferroelectric domain to the\nnext, and that the magnetic domain walls may be charged or uncharged depending\non the magnetic field history. Micromagnetic simulations show that the\nproperties of the domain walls vary depending on the magnetoelastic easy axis\nconfiguration and the charged or uncharged nature of the wall. The\nconfiguration where the easy axis alternates by 60$^\\circ$ and a charged wall\nis initialised exhibits the largest change in domain wall width from 192 nm to\n119 nm as a function of in-plane magnetic field. Domain wall width tuning\nprovides an additional degree of freedom for devices that seek to manipulate\nmagnetic domain walls using strain coupling to ferroelectrics.",
        "positive": "Charge-transfer effect in hard x-ray 1$s$ and 2$p$ photoemission\n  spectra: LDA+DMFT and cluster-model analysis: We study $1s$ and $2p$ hard x-ray photoemission spectra (XPS) in a series of\nlate transition metal oxides: Fe$_2$O$_3$ (3$d^{5}$), FeTiO$_3$ (3$d^{6}$), CoO\n(3$d^{7}$) and NiO (3$d^{8}$). The experimental spectra are analyzed with two\ntheoretical approaches: the MO$_6$ cluster model and the local density\napproximation (LDA) + dynamical mean-field theory (DMFT). Owing to the absence\nof the core-valence multiplets and spin-orbit coupling, 1$s$ XPS is found to be\na sensitive probe of chemical bonding and nonlocal charge-transfer screening,\nproviding complementary information to 2$p$ XPS. The 1$s$ XPS spectra are used\nto assess the accuracy of the $ab$-initio LDA+DMFT approach, developed recently\nto study the material-specific charge-transfer effects in core-level XPS."
    },
    {
        "anchor": "Magnetic and humidity sensing properties of nanostructured\n  Cu[x]Co[1-x]Fe2O4 synthesized by auto combustion technique: Magnetic nanomaterials (23-43 nm) of Cu$_x$Co$_{1-x}$Fe$_2$O$_4$\\ (x = 0.0,\n0.5 and 1.0) were synthesized by auto combustion method. The crystallite sizes\nof these materials were calculated from X-ray diffraction peaks. The band\nobserved in Fourier transform infrared spectrum near 575 cm$^{-1}$ in these\nsamples confirm the presence of ferrite phase. Conductivity measurement shows\nthe thermal hysteresis and demonstrates the knee points at 475$^o$C, 525$^o$C\nand 500$^o$C for copper ferrite, cobalt ferrite and copper-cobalt mixed ferrite\nrespectively. The hystersis M-H loops for these materials were traced using the\nVibrating Sample Magnetometer (VSM) and indicate a significant increase in the\nsaturation magnetization (M$_s$) and remanence (M$_r$) due to the substitution\nof Cu$^{2+}$ ions in cobalt ferrite, while the intrinsic coercivity (H$_c$) was\ndecreasing. Among these ferrites, copper ferrite exhibits highest sensitivity\nfor humidity.",
        "positive": "Tunable excitonic insulator in quantum limit graphite: Half a century ago, Mott noted that tuning the carrier density of a semimetal\ntowards zero produces an insulating state in which electrons and holes form\nbound pairs. It was later argued that such pairing persists even if a\nsemiconducting gap opens in the underlying band structure, giving rise to what\nhas become known as the strong coupling limit of an `excitonic insulator.'\nWhile these `weak' and `strong' coupling extremes were subsequently proposed to\nbe manifestations of the same excitonic state of electronic matter, the\npredicted continuity of such a phase across a band gap opening has not been\nrealized experimentally in any material. Here we show the quantum limit of\ngraphite, by way of temperature and angle-resolved magnetoresistance\nmeasurements, to host such an excitonic insulator phase that evolves\ncontinuously between the weak and strong coupling limits. We find that the\nmaximum transition temperature T_EI of the excitonic phase is coincident with a\nband gap opening in the underlying electronic structure at B_0= 46 +/- 1 T,\nwhich is evidenced above T_EI by a thermally broadened inflection point in the\nmagnetoresistance. The overall asymmetry of the observed phase boundary around\nB_0 closely matches theoretical predictions of a magnetic field-tuned excitonic\ninsulator phase in which the opening of a band gap marks a crossover from\npredominantly momentum-space pairing to real-space pairing."
    },
    {
        "anchor": "Terahertz Magnetic and Lattice Excitations in van der Waals Ferromagnet\n  VI3: We use the synergy of infrared, terahertz, and Raman spectroscopies with DFT\ncalculations to shed light on the magnetic and lattice properties of VI3. The\nstructural transition at TS1 = 79 K is accompanied by a large splitting of\npolar phonon modes. Below TS1, strong ferromagnetic fluctuations are observed.\nThe variations of phonon frequencies at 55 K induced by magnetoelastic coupling\nenhanced by spin-orbit interaction indicate the proximity of long-range\nferromagnetic order. Below TC = 50 K, two Raman modes simultaneously appear and\nshow dramatic softening in the narrow interval around the temperature TS2 of\nthe second structural transition associated with the order-order magnetic phase\ntransition. Below TS2, a magnon in the THz range appears in Raman spectra. The\nTHz magnon observed in VI3 indicates the application potential of 2D van der\nWaals ferromagnets in ultrafast THz spintronics, which has previously been\nconsidered an exclusive domain of antiferromagnets.",
        "positive": "Crack Path Selection in Orientationally Ordered Composites: While cracks in isotropic homogeneous materials propagate straight,\nperpendicularly to the tensile axis, cracks in natural and synthetic composites\ndeflect from a straight path, often increasing the toughness of the material.\nHere we combine experiments and simulations to identify materials properties\nthat predict whether cracks propagate straight or kink on a macroscale larger\nthan the composite microstructure. Those properties include the anisotropy of\nthe fracture energy, which we vary several folds by increasing the volume\nfraction of orientationally ordered alumina platelets inside a polymer matrix,\nand a microstructure-dependent process zone size that is found to modulate the\nadditional stabilizing or destabilizing effect of the non-singular stress\nacting parallel to the crack. Those properties predict the existence of an\nanisotropy threshold for crack kinking and explain the surprisingly strong\ndependence of this threshold on sample geometry and load distribution."
    },
    {
        "anchor": "Crystal Structure Prediction Supported by Incomplete Experimental Data: The prediction of material structure from chemical composition has been a\nlong-standing challenge in natural science. Although there have been various\nmethodological developments and successes with computer simulations, the\nprediction of crystal structures comprising more than several tens of atoms in\nthe unit cell still remains difficult due to the many degrees of freedom, which\nincrease exponentially with the number of atoms. Here we show that when some\nexperimental data is available, even if it is totally insufficient for\nconventional structure analysis, it can be utilized to support and\nsubstantially accelerate structure simulation. In particular, we formulate a\ncost function based on a weighted sum of interatomic potential energies and a\npenalty function referred to as \"crystallinity\", which is defined using limited\nX-ray diffraction data. This method is applied to well-known polymorphs of\n$\\rm{SiO_2}$ with up to 96 atoms in the simulation cell to find that it\nreproduces the correct structures efficiently with a very limited number of\ndiffraction peaks. The penalty function is confirmed to destabilize the local\nminima of the potential energy surface, which facilitates finding the correct\nstructure. This method opens a new avenue for determining and predicting\nstructures that are difficult to determine by conventional methods, such as\nsurface, interface, glass, and amorphous structures.",
        "positive": "Nanoparticle size distribution estimation by full-pattern powder\n  diffraction analysis: The increasing scientific and technological interest in nanoparticles has\nraised the need for fast, efficient and precise characterization techniques.\nPowder diffraction is a very efficient experimental method, as it is\nstraightforward and non-destructive. However, its use for extracting\ninformation regarding very small particles brings some common crystallographic\napproximations to and beyond their limits of validity. Powder pattern\ndiffraction calculation methods are critically discussed, with special focus on\nspherical particles with log-normal distribution, with the target of\ndetermining size distribution parameters. A 20-nm CeO$_{2}$ sample is analyzed\nas example."
    },
    {
        "anchor": "The importance of sigma bonding electrons for the accurate description\n  of electron correlation in graphene: Electron correlation in graphene is unique because of the interplay of the\nDirac cone dispersion of $\\pi$ electrons with long range Coulomb interaction.\nThe random phase approximation predicts no metallic screening at long distance\nand low energy because of the zero density of states at Fermi level, so one\nmight expect that graphene should be a poorly screened system. However,\nempirically graphene is a weakly interacting semimetal, which leads to the\nquestion of how electron correlations take place in graphene at different\nlength scales. We address this question by computing the equal time and dynamic\nstructure factor $S(\\vec q)$ and $S(\\vec q, \\omega)$ of freestanding graphene\nusing {\\it ab-initio} fixed-node diffusion Monte Carlo and the random phase\napproximation. We find that the $\\sigma$ electrons contribute strongly to\n$S(\\vec q,\\omega)$ for relevant experimental values of $\\omega$ even at\ndistances up to around 80 \\AA. These findings illustrate how the emergent\nphysics from underlying Coulomb interactions results in the observed weakly\ncorrelated semimetal.",
        "positive": "Effects of Lower Symmetry and Dimensionality on Raman Spectra in 2D WSe2: We report the observation and interpretation of new Raman peaks in few-layer\ntungsten diselenide (WSe2), induced by the reduction of symmetry going from 3D\nto 2D. In general, Raman frequencies in 2D materials follow quite closely the\nfrequencies of corresponding eigenmodes in the bulk. However, while the modes\nthat are Raman active in the bulk are also Raman active in the thin films, the\nreverse is not always true due to the reduced symmetry in thin films. Here, we\npredict from group theory and density functional calculations that two\nintra-layer vibrational modes which are Raman inactive in bulk WSe2 in our\nexperimental configuration become Raman active in thin film WSe2, due to\nreduced symmetry in thin films. This phenomenon explains the Raman peaks we\nobserve experimentally at ~310 cm-1 and 176 cm-1 in thin film WSe2.\nInterestingly, the bulk mode at ~310 cm-1 that is Raman inactive can in fact be\ndetected in Raman measurements under specific wavelengths of irradiation,\nsuggesting that in this case, crystal symmetry selection rules may be broken\ndue to resonant scattering. Both theory and experiment indicate that the and\nmodes blue-shift with decreasing thickness, which we attribute to surface\neffects. Our results shed light on a general understanding of the Raman/IR\nactivities of the phonon modes in layered transition metal dichalcogenide\nmaterials and their evolution behavior from 3D to 2D."
    },
    {
        "anchor": "Improved time integration for phase-field crystal models of\n  solidification: We optimize a numerical time-stabilization routine for the phase-field\ncrystal (PFC) models of solidification. By numerical experiments, we showcase\nthat our approach can improve the accuracy of underlying time integration\nschemes by a few orders of magnitude. We investigate different time integration\nschemes. Moreover, as a prototypical example for applications, we extend our\nnumerical approach to a PFC model of solidification with an explicit\ntemperature coupling.",
        "positive": "Observation of a molecule-metal interface charge transfer state by\n  resonant photoelectron spectroscopy: We report the discovery of a novel charge transfer (CT) state at a\nmolecule-metal interface by the application of resonant photoelectron\nspectroscopy (ResPES). This interface feature is neither present for molecular\nbulk samples nor for the clean substrate. Within a simplified two-step model\nthis signal is assigned to a particular final state that is invisible in direct\nphotoelectron spectroscopy but in ResPES revealed through relative resonant\nenhancement. A detailed analysis of the spectroscopic signature of the CT state\nshows characteristics of electronic interaction not found in other electron\nspectroscopic techniques. Our study demonstrates the sensitivity of ResPES to\nsuch interactions and constitutes a new way to investigate CT at molecule-metal\ninterfaces."
    },
    {
        "anchor": "First-principles approach to Non-Collinear Magnetism: towards\n  Spin-dynamics: A description of non-collinear magnetism in the framework of spin-density\nfunctional theory is presented for the exact exchange energy functional which\ndepends explicitly on two-component spinor orbitals. The equations for the\neffective Kohn-Sham scalar potential and magnetic field are derived within the\noptimized effective potential (OEP) framework. With the example of a\nmagnetically frustrated Cr monolayer it is shown that the resulting\nmagnetization density exhibits much more non-collinear structure than standard\ncalculations. Furthermore, a time-dependent generalization of the non-collinear\nOEP method is well suited for an ab-initio description of spin dynamics. We\nalso show that the magnetic moments of solids Fe, Co and Ni are well\nreproduced.",
        "positive": "Lattice structure dependence of laser-induced ultrafast magnetization\n  switching in ferrimagnets: The experimental discovery of single-pulse ultrafast magnetization switching\nin ferrimagnetic alloys, such as GdFeCo and MnRuGa, opened the door to a\npromising route toward faster and more energy efficient data storage. A recent\nsemi-phenomenological theory has proposed that a fast, laser-induced\ndemagnetization below a threshold value puts the system into a dynamical regime\nwhere angular momentum transfer between sublattices dominates. Notably, this\nthreshold scales inversely proportional to the number of exchange-coupled\nnearest neighbours considered in the model, which in the simplest case is\ndirectly linked to the underlying lattice structure. In this work, we study the\nrole of the lattice structure on the laser-induced ultrafast magnetization\nswitching in ferrimagnets by complementing the phenomenological theory with\natomistic spin dynamics computer simulations. We consider a spin model of the\nferrimagnetic GdFeCo alloy with increasing number of exchange-coupled\nneighbours. Within this model, we demonstrate that the laser-induced\nmagnetization dynamics and switching depends on the lattice structure. Further,\nwe determine that the critical laser energy for switching reduces for\ndecreasing number of exchange-coupled neighbours."
    },
    {
        "anchor": "Ordering of Fe and Zn ions and magnetic properties of FeZnMo3O8: In the present paper electronic, magnetic, and structural properties of a\nnovel system FeZnMo$_3$O$_8$ with a polar crystal structure are investigated\nusing GGA+U calculations. It is shown that Fe ions preferably occupy octahedral\nand Zn ions tetrahedral positions. This structural feature is caused by\ndifferent ionic radii of these ions and not by the exchange coupling. The\ncalculated exchange constants naturally explain magnetic structure observed in\nthis material.",
        "positive": "Transferable Interatomic Potentials for Aluminum from Ambient Conditions\n  to Warm Dense Matter: We present a study on the transport and materials properties of aluminum\nspanning from ambient to warm dense matter conditions using a machine-learned\ninteratomic potential (ML-IAP). Prior research has utilized ML-IAPs to simulate\nphenomena in warm dense matter, but these potentials have often been calibrated\nfor a narrow range of temperature and pressures. In contrast, we train a single\nML-IAP over a wide range of temperatures, using density functional theory\nmolecular dynamics (DFT-MD) data. Our approach overcomes computational\nlimitations of DFT-MD simulations, enabling us to study transport and materials\nproperties of matter at higher temperatures and longer time scales. We\ndemonstrate the ML-IAP transferability across a wide range of temperatures\nusing molecular-dynamics (MD) by examining the thermal conductivity, diffusion\ncoefficient, viscosity, sound velocity, and ion-ion structure factor of\naluminum up to about 60,000 K, where we find good agreement with previous\ntheoretical data."
    },
    {
        "anchor": "Comment on \"Fast and Accurate Modeling of Molecular Atomization Energies\n  with Machine Learning\": A Comment on the Letter by M. Rupp et al., Phys. Rev. Lett. 108 058301\n(2012).",
        "positive": "NMR parameters in gapped graphene systems: We calculate the nuclear spin-lattice relaxation time and the Knight shift\nfor the case of gapped graphene systems. Our calculations consider both the\nmassive and massless gap scenarios. Both the spin-lattice relaxation time and\nthe Knight shift depend on temperature, chemical potential, and the value of\nthe electronic energy gap. In particular, at the Dirac point, the electronic\nenergy gap has stronger effects on the system nuclear magnetic resonance\nparameters in the case of the massless gap scenario. Differently, at large\nvalues of the chemical potential, both gap scenarios behave in a similar way\nand the gapped graphene system approaches a Fermi gas from the nuclear magnetic\nresonance parameters point of view. Our results are important for nuclear\nmagnetic resonance measurements that target the $^{13}$C active nuclei in\ngraphene samples."
    },
    {
        "anchor": "SrRietveld: A program for automating Rietveld refinements for high\n  throughput powder diffraction studies: SrRietveld is a highly automated software toolkit for Rietveld refinement.\nCompared to traditional refinement programs, it is more efficient to use and\neasier to learn. It is designed for modern high throughput diffractometers and\ncapable of processing large numbers of data-sets with minimal effort. The new\nsoftware currently uses conventional Rietveld refinement engines, automating\nGSAS and FullProf refinements. However, as well as automating and extending\nmany tasks associated with these programs, it is designed in a flexible and\nextensible way so that in the future these engines can be replaced with new\nrefinement engines as they become available. SrRietveld is an open source\nsoftware package developed in Python.",
        "positive": "M\u00f6bius boron-nitride nanobelts interacting with heavy metal\n  nanoclusters: How do nickel, cadmium, and lead nanoclusters interact with boron-nitride and\nMobius-type boron-nitride nanobelts? To answer this question, we used the\nsemiempirical tight binding framework, as implemented in the xTB software, to\ndetermine the lowest energy geometries, binding energy, complexes stability,\nand electronic properties. Our calculations show that heavy metal nanoclusters\nfavorably bind to both boron-nitride nanobelts, although the interaction is\nstronger with the Mobius-type nanobelt. The calculations show that the nickel\nnanocluster has the lowest binding energy and the greatest charge transfer with\nthe nanobelts, followed by the cadmium and lead nanoclusters. During the\nsimulation time, the molecular dynamic simulation showed that all complexes\nwere stable at 298 K. Following the nanobelt's symmetry, the frontier orbitals\nare distributed homogeneously throughout the structure. This distribution\nchanged when the nanobelt was twisted to create the Mobius-type nanobelt. The\ntopological study indicated that the number of bonds between the metal\nnanoclusters and the Mobius-type nanobelt doubled and that the bonds formed\nwith the nickel nanocluster were stronger than those formed with the cadmium\nand lead metals. Combining all the results, we conclude that the nickel\nnanoclusters are chemisorbed, whereas the cadmium and lead nanoclusters are\nphysisorbed in both nanobelts."
    },
    {
        "anchor": "Interface properties of CsPbBr$_3$ /CsPbI$_3$ perovskite heterostructure\n  for solar cell: We explore the interface properties of perovskite heterostructure\nCsPbBr$_3$/CsPbI$_3$ through first-principles calculations. The structural\ninterface is formed by the bonding of Cs-Br and Cs-I with bond length of\n$\\sim$4.106 and 3.922 \\AA. The upshift of Goldsmith tolerance factor in the\nrange $0.8<t<1$ from $t<0.8$ is revealed for the bi-layer interface, from bulk,\nreflecting the structural rearrangement from anisotropy to isotropy in\nconfinement. The band gap arises mainly due to the energy difference of I-5p\norbital than that of Br-4p at the valence band and Pb-6p at the conduction\nband. Heavier halide shows the red shift in the absorption spectra, for the\npristine monolayer component. For the bilayer geometry, iodine contribution is\nmore observed than that of bromine and the underlying interface properties may\nbe useful for solar cell devices application.",
        "positive": "Doping Li-rich cathode material Li$_2$MnO$_3$: Interplay between lattice\n  site preference, electronic structure, and delithiation mechanism: We report a detailed first-principles study of doping in Li$_2$MnO$_3$, in\nboth the dilute doping limit and heavy doping, using hybrid density-functional\ncalculations. We find that Al, Fe, Mo, and Ru impurities are energetically most\nfavorable when incorporated into Li$_2$MnO$_3$ at the Mn site, whereas Mg is\nmost favorable when doped at the Li sites. Ni, on the other hand, can be\nincorporated at the Li site and/or the Mn site, and the distribution of Ni over\nthe lattice sites can be tuned by tuning the materials preparation conditions.\nThere is a strong interplay between the lattice site preference and charge and\nspin states of the dopant, the electronic structure of the doped material, and\nthe delithiation mechanism. The calculated electronic structure and voltage\nprofile indicate that, in Ni-, Mo-, or Ru-doped Li$_2$MnO$_3$, oxidation occurs\non the electrochemically active transition-metal ion(s) before it does on\noxygen during the delithiation process. The role of the dopants is to provide\ncharge-compensation and bulk electronic conduction mechanisms in the initial\nstages of delithiation, hence enabling the oxidation of the lattice oxygen in\nthe later stages. This work thus illustrates how the oxygen-oxidation mechanism\ncan be used in combination with the conventional mechanism involving\ntransition-metal cations in design of high-capacity battery cathode materials."
    },
    {
        "anchor": "Oxygen vacancy induced electronic structure modification of KTaO$_3$: The observation of metallic interface between band insulators LaAlO$_3$ and\nSrTiO$_3$ has led to massive efforts to understand the origin of the phenomenon\nas well as to search for other systems hosting such two dimensional electron\ngases (2-DEG). However, the understanding of the origin of the 2-DEG is very\noften hindered as several possible mechanisms such as polar catastrophe,\ncationic intermixing and oxygen vacancy (OV) etc. can be operative\nsimultaneously. The presence of a heavy element makes KTaO$_3$ (KTO) based\n2-DEG a potential platform to investigate spin orbit coupling driven novel\nelectronic and magnetic phenomena. In this work, we investigate the sole effect\nof the OV, which makes KTO metallic. Our detailed \\textit{ab initio}\ncalculations not only find partially filled conduction bands in the presence of\nan OV but also predict a highly localized mid-gap state due to the linear\nclustering of OVs around Ta. Photoluminescence measurements indeed reveal the\nexistence of such mid-gap state and O $K$-edge X-ray absorption spectroscopy\nfinds electron doping in Ta $t_{2g}^*$ antibonding states. This present work\nsuggests that one should be cautious about the possible presence of OVs within\nKTO substrate in interpreting metallic behavior of KTO based 2-DEG.",
        "positive": "Nonlinear evolution equations for degenerate transverse waves in\n  anisotropic elastic solids: Transverse elastic waves behave differently in nonlinear isotropic and\nanisotropic media. Quadratically nonlinear coupling in the evolution equations\nfor wave amplitudes is not possible in isotropic solids, but such a coupling\nmay occur for certain directions in anisotropic materials. We identify the\nexpression responsible for the coupling and we derive coupled canonical\nevolution equations for transverse wave amplitudes in the case of two-fold and\nthree-fold symmetry acoustic axes. We illustrate our considerations by examples\nfor a cubic crystal."
    },
    {
        "anchor": "Spin Dynamics Simulation of the magnetization reversal process in FM/AFM\n  bilayer structures by Anisotropic Heisenberg Model: We have studied the magnetization reversal process in FM/AFM bilayer\nstructures through of spin dynamics simulation. It has been observed that the\nmagnetization behavior is different at each branch of the hysteresis loop as\nwell as the exchange-bias behavior. On the descending branch a sudden change of\nthe magnetization is observed while on the ascending branch is observed a bland\nchange of the magnetization. The occurrence of the asymmetry in the hysteresis\nloop and the variation in the exchange-bias is due to anisotropy which is\nintroduced only in the coupling between ferromagnetic (FM) and\nantiferromagnetic (AFM) layers.",
        "positive": "Intrinsic disorder in graphene on transition metal dichalcogenide\n  heterostructures: The electronic properties of two-dimensional materials such as graphene are\nextremely sensitive to their environment, especially the underlying substrate.\nPlanar van der Waals bonded substrates such as hexagonal boron nitride (hBN)\nhave been shown to greatly improve the electrical performance of graphene\ndevices by reducing topographic variations and charge fluctuations compared to\namorphous insulating substrates}. Semiconducting transition metal\ndichalchogenides (TMDs) are another family of van der Waals bonded materials\nthat have recently received interest as alternative substrates to hBN for\ngraphene as well as for components in novel graphene-based device\nheterostructures. Additionally, their semiconducting nature permits dynamic\ngate voltage control over the interaction strength with graphene. Through local\nscanning probe measurements we find that crystalline defects intrinsic to TMDs\ninduce scattering in graphene which results in significant degradation of the\nheterostructure quality, particularly compared to similar graphene on hBN\ndevices."
    },
    {
        "anchor": "Wave localization in stratified square-cell lattices. The antiplane\n  problem: Steady-state and transient antiplane dynamic processes in a structured solids\nconsisting of uniform periodic square-cell lattices connected by a lattice\nlayer of different bond stiffnesses and point masses are analyzed. A\nsemi-infinite lattice covered by a layer is also considered. Localization\nphenomena that are characterized by a waveguide-like propagation along the\nlayer direction and exponential attenuation along its normal are studied.\nWaveguide pass-bands and attenuation factors are obtained analytically, while\ntransient processes developed under the action of a monochromatic local source\nare numerically simulated. As a result, it is shown how a two-dimensional\nproblem is transformed with time into a quasi-one-dimensional one and how a\nlayer traps the source energy. Special attention is paid to revealing\nparticularities of transient waves in cases where steady-state solutions are\nabsent: resonant waves with frequencies demarcating pass- and stop-bands at the\nends of the Brillouin zone and wave transition in the vicinities of transition\npoints in dispersion curves. In the latter case, a simultaneous onset of\ndifferent localization phenomena - a spatial star-like beaming and a\none-dimensional waveguide-like localization - is shown.",
        "positive": "rf SQUID metamaterials: An rf superconducting quantum interference device (SQUID) array in an\nalternating magnetic field is investigated with respect to its effective\nmagnetic permeability, within the effective medium approximation. This system\nacts as an inherently nonlinear magnetic metamaterial, leading to negative\nmagnetic response, and thus negative permeability, above the resonance\nfrequency of the individual SQUIDs. Moreover, the permeability exhibits\noscillatory behavior at low field intensities, allowing its tuning by a slight\nchange of the intensity of the applied field."
    },
    {
        "anchor": "Self-diffusion in carbon-alloyed CoCrFeMnNi high entropy alloys: Tracer diffusion of the substitutional components in\n(CoCrFeNiMn)$_{1-x}$C$_x$ high-entropy alloys with x = 0.002, 0.005 and 0.008\n(in at. fractions) is measured at elevated temperatures from 1173 to 1373 K.\nTwo different characteristic effects of interstitial carbon addition on\nsubstitutional diffusion in these FCC alloys are distinguished. At the highest\ntemperature of 1373 K, alloying by C with relatively low concentrations (x =\n0.002) retards diffusion of the substitutional elements with respect to those\nin the C-free alloy. At lower temperatures and/or higher C concentrations (x >\n0.005), an enhancement of the diffusion rates of all substitutional elements is\nseen. A model is suggested that relates the self-diffusivities in the\nCoCrFeMnNi-C alloys with the lattice distortion imposed by interstitially\ndissolved carbon. The experimental results are interpreted in terms of a\ndecrease of the migration barriers for vacancy-mediated diffusion due to the\npresence of interstitial C atoms.",
        "positive": "Topological Phase Diagram of BiTeX--Graphene Hybrid Structures: Combining graphene with other novel layered materials is a possible way for\nengineering the band structure of charge carriers. Strong spin-orbit coupling\nin BiTeX compounds and the recent fabrication of a single layer of BiTeI points\ntowards a feasible experimental realization of a Kane--Mele phase in\ngraphene-based heterostructures. Here, we theoretically demonstrate the\ntunability of the topological phase of hybrid systems built from graphene and\nBiTeX (X = I, Br, Cl) layers by uniaxial in-plane tensile and out-of plane\ncompressive strain. We show that structural stress inherently present in\nfabricated samples could induce a topological phase transition, thus turning\nthe sample in a novel experimental realization of a time reversal invariant\ntopological insulator."
    },
    {
        "anchor": "Ferroelectricity and Antiferroelectricity in Elemental Group-V Monolayer\n  Materials: Ferroelectricity is usually found in compound materials composed by different\nelements. Here, based on first-principles calculations, we reveal the first\nexample of spontaneous electrical polarization and ferroelectricity in stable\ntwo-dimensional elemental materials: elemental Group-V (As, Sb, and Bi)\nmonolayers. The polarization is due to the spontaneous lattice distortion with\natomic layer buckling. Interestingly, for Bi monolayer, apart from the\nferroelectric phase, we find that it can also host an antiferroelectric phase.\nThe Curie temperatures of these elemental materials can be higher than room\ntemperature, making them promising for realizing ultrathin ferroelectric\ndevices of broad interest.",
        "positive": "Stable room temperature magnetic graphite: Carbon materials are attracting increasing attention due to the novelty of\nthe associated physical properties and the potential applications in high-tech\ndevices. The possibility to achieve outstanding properties in macroscopic\ncarbon materials opens up a profusion of new striking applications. Magnetic\nproperties induced by defects on graphite structures, such as pores, edges of\nthe planes and topological defects, have been theoretically predicted. The\npossible coexistence of sp3 and sp2 bonds have been also invoked to predict\nthis behavior (for a review, see ref. 1). Some reports have proved the\nexistence of weak ferromagnetic-like magnetization loops in highly-oriented\npyrolytic graphite (HOPG) (ref. 2-3). Very recently two reports showed that the\nexistence of ferromagnetism in pure carbon is unambiguously possible (ref.\n4-5). Here we report on a novel and inexpensive chemical route consistent in a\ncontrolled etching on the graphite structure to obtain macroscopic amounts of\nmagnetic pure graphite. This material has a strong magnetic response even at\nroom temperature where it can be attracted by a commercial magnet and would be\nthe experimental confirmation for the defect induced magnetism previously\npredicted."
    },
    {
        "anchor": "Mechanism of saponite crystallization from a rapidly formed amorphous\n  intermediate: Although clays are crucial mineral phases in Earth's weathering engine, it is\nunclear how they form in surface environments under (near-)ambient pressures\nand temperature. Most synthesis routes, attempting to give insights into the\nplausible mechanisms, rely on hydrothermal conditions, yet many geological\nstudies showed that clays may actually form at moderate temperatures (< 100\ndeg. C) in most terrestrial settings. Here, we present the mechanism of the\nlow-temperature (25-95 deg. C) crystallization of a synthetic Mg-clay,\nsaponite. We describe the pathway at the various sub-stages of the reaction, as\nwe derived from high-energy X-ray diffraction, infrared spectroscopy and\ntransmission electron microscopy data. Our results reveal that saponite\ncrystallizes via a two stage process: 1) a rapid (several minutes)\nco-precipitation where ~20% of the available magnesium becomes incorporated\ninto an aluminosilicate network followed by 2) a much slower crystallization\nmechanism (many hours to days) where the remaining magnesium becomes gradually\nincorporated into the growing saponite sheet structure.",
        "positive": "Wide Field Imaging of van der Waals Ferromagnet Fe3GeTe2 by Spin Defects\n  in Hexagonal Boron Nitride: Emergent color centers with accessible spins hosted by van der Waals\nmaterials have attracted substantial interest in recent years due to their\nsignificant potential for implementing transformative quantum sensing\ntechnologies. Hexagonal boron nitride (hBN) is naturally relevant in this\ncontext due to its remarkable ease of integration into devices consisting of\nlow-dimensional materials. Taking advantage of boron vacancy spin defects in\nhBN, we report nanoscale quantum imaging of low-dimensional ferromagnetism\nsustained in Fe3GeTe2/hBN van der Waals heterostructures. Exploiting spin\nrelaxometry methods, we have further observed spatially varying magnetic\nfluctuations in the exfoliated Fe3GeTe2 flake, whose magnitude reaches a peak\nvalue around the Curie temperature. Our results demonstrate the capability of\nspin defects in hBN of investigating local magnetic properties of layered\nmaterials in an accessible and precise way, which can be extended readily to a\nbroad range of miniaturized van der Waals heterostructure systems."
    },
    {
        "anchor": "Electric Polarization in YCrO3 Induced by Restricted Polar Domains of\n  Magnetic and Structural Natures: The electric polarization induced by local polar domains of two types (phase\nseparation domains of magnetic nature and structure-distorted domains) has been\nobserved in YCrO3 single crystals. These domains form a superparaelectric\nstate. Below some temperatures, in the frozen superparaelectric state, the\npyrocurrent maxima and the hysteresis loops with remanent polarization are\nobserved as along axis c so in directions [110]. The polarization exists to the\ntemperatures depending on the orientation of electric field with respect to the\ncrystal axes. The sources of formation of such local domains are analyzed and\ntheir properties are studied.",
        "positive": "Nanoporous ionic organic networks: from synthesis to materials\n  applications: The past decade has witnessed the rapid progress in synthesizing nanoporous\norganic networks or polymer frameworks for various potential applications.\nGenerally speaking, functionalization of porous networks to add extra\nproperties and enhance materials performance could be achieved either during\nthe pore formation (thus a concurrent approach) or post-synthetic modification\n(a sequential approach). Nanoporous organic networks which include ion pairs in\na covalent manner are of special importance and possess extreme application\nprofiles. Within these nanoporous ionic organic networks (NIONs), here with a\npore size in the range from sub-1 nm to 100 nm, we observe a synergistic\ncoupling of the electrostatic interaction of charges, the nanoconfinement\nwithin pores and the addressable functional units in soft matter resulting in a\nwide variety of functions and applications, above all catalysis, energy storage\nand conversion, as well as environmental operations. This review aims to\nhighlight the recent progress in this area, and seeks to raise original\nperspectives that will stimulate future advancements at both the fundamental\nand applied level."
    },
    {
        "anchor": "Strongly reshaped organic-metal interfaces: Tetracyanoethylene on\n  Cu(100): The interaction of the strong electron-acceptor tetracyanoethylene (TCNE)\nwith the Cu(100) surface has been studied with scanning tunneling microscopy\nexperiments and first-principles density functional theory calculations. We\ncompare two different adsorption models with the experimental results and show\nthat the molecular self-assembly is caused by a strong structural modification\nof the Cu(100) surface rather than the formation of a coordination network by\ndiffusing Cu adatoms. Surface atoms become highly buckled and the chemisorption\nof TCNE is accompanied by a partial charge-transfer.",
        "positive": "Interplay between strain, defect charge state and functionality in\n  complex oxides: We use first-principles calculations to investigate the interplay between\nstrain and the charge state of point defect impurities in complex oxides. Our\nwork is motivated by recent interest in using defects as active elements to\nprovide novel functionality in coherent epitaxial films. Using oxygen vacancies\nas model point defects, and CaMnO$_3$ and MnO as model materials, we calculate\nthe changes in internal strain caused by changing the charge state of the\nvacancies, and conversely the effect of strain on charge-state stability. Our\nresults show that the charge state is a degree of freedom that can be used to\ncontrol the interaction of defects with strain and hence the concentration and\nlocation of defects in epitaxial films. We propose the use of field-effect\ngating to reversibly change the charge state of defects and hence the internal\nstrain and corresponding strain-induced functionalities."
    },
    {
        "anchor": "A screw dislocation in a functionally graded material using the\n  translation gauge theory of dislocations: The aim of this paper is to provide new results and insights for a screw\ndislocation in functionally graded media within the gauge theory of\ndislocations. We present the equations of motion for dislocations in\ninhomogeneous media. We specify the equations of motion for a screw dislocation\nin a functionally graded material. The material properties are assumed to vary\nexponentially along the x and y-directions. In the present work we give the\nanalytical gauge field theoretic solution to the problem of a screw dislocation\nin inhomogeneous media. Using the dislocation gauge approach, rigorous\nanalytical expressions for the elastic distortions, the force stresses, the\ndislocation density and the pseudomoment stresses are obtained depending on the\nmoduli of gradation and an effective intrinsic length scale characteristic for\nthe functionally graded material under consideration.",
        "positive": "Large magnetothermopower effect in Dirac materials (Sr/Ca)MnBi2: We report temperature and magnetic field dependence of the thermal transport\nproperties in single crystals of (Sr/Ca)MnBi$_2$ with linear energy dispersion.\nIn SrMnBi$_2$ thermopower is positive, indicating hole-type carriers and the\nmagnetic field enhances the thermopower significantly. The maximum change of\nthermopower is about 1600% in 9 T field and at 10 K. A negative thermopower is\nobserved in CaMnBi$_2$ with dominant electron-type carriers and, in contrast,\nthe magnetic field suppresses the absolute value of thermopower.\nFirst-principle band structure shows that the chemical potential is close to\nthe Dirac-cone-like points in linear bands. The magnetic field suppresses the\napparent Hall carrier density of CaMnBi$_2$ below 50 K. The large\nmagnetothermopower effect in (Sr/Ca)MnBi$_2$ is attributed to the magnetic\nfield shift of chemical potential"
    },
    {
        "anchor": "Ab-initio Theoretical Description of the Interrelation between\n  Magnetocrystalline Anisotropy and Atomic Short-Range Order: The cubic lattice symmetry of ferromagnetic homogeneously disordered alloys\nis when a compositional modulation is imposed. This can have a profound\ninfluence on the magnetocrystalline anisotropy energy (MAE). We describe our\nab-initio theory of this effect and use the framework of concentration waves\nwith the electronic structure described within the spin-polarised relativistic\nKorringa-Kohn-Rostoker coherent-potential approximation. We find that ordering\nproduces a 2 order of magnitude increase in the MAE as well as altering the\nequilibrium direction of magnetisation. Using the same theoretical framework we\nalso examine directional compositional order produced by magnetic annealing\nwith an explicit study of permalloy.",
        "positive": "Thermoelectric properties of Bi2O2Se single crystals: Bismuth oxyselenide (Bi$_2$O$_2$Se) attracts great interest as a potential\nn-type complement to p-type thermoelectric oxides in practical applications.\nPrevious investigations were generally focused on polycrystals. Here, we\nperformed a study on the thermoelectric properties of Bi$_2$O$_2$Se single\ncrystals. Our samples exhibit electron mobility as high as 250\ncm$^2.$V$^{-1}$.s$^{-1}$ and thermal conductivity as low as $2$\nW.m$^{-1}$.K$^{-1}$ near room temperature. The maximized figure of merit is\nyielded to be 0.188 at 390 K, higher than that of polycrystals. Consequently, a\nrough estimation of the phonon mean free path ($\\ell_\\textrm{ph}$) from the\nkinetic model amounts to 12 $\\r{A}$ at 390 K and follows a $T^{-1}$ behavior.\nAn extrapolation of $\\ell_\\textrm{ph}$ to higher temperatures indicates that\nthis system approaches the Ioffe-Regel limit at about 1100 K. In light of the\nphonon dispersions, we argue that the ultralow $\\ell_\\textrm{ph}$ is attributed\nto intense anharmonic phonon-phonon scattering, including Umklapp process and\nacoustic to optical phonon scattering. Our results suggest that single crystals\nprovide a further improvement of thermoelectric performance of Bi$_2$O$_2$Se."
    },
    {
        "anchor": "Simultaneous Oxygen and Boron Trifluoride Functionalization of Hexagonal\n  Boron Nitride: A Designer Cathode Material for Energy Storage: Covalent functionalization is a way to tune the electrochemical properties of\nhexagonal boron nitride (h-BN) monolayers. The wide band gap insulator h-BN may\nbecome metallic conductor upon functionalization with strong oxidants, such as\nfluorosulfonyl radicals ($\\cdot$OSO$_2$F), as known since 1978 [N. Bartlett et\nal., J. Chem. Soc. Chem. Comm. {\\bf 5}, 200 (1978)], with electrical\nconductivity of 1.5 S/cm [C. Shen et al., J. Solid State Chem. {\\bf 147}, 74\n(1999)] that greatly surpasses commercial cathode material Li$_{x}$CoO$_{2}$\nwhile retaining excellent ionic conductivity. Functionalized boron nitrides\n(FBN-s) have great potential for cathode applications in energy storage\ndevices, for example in solid state batteries. While fluorosulfonyl\nfunctionalization is unlikely to result in rechargeable cathodes, similarly to\ngraphene fluoride (CF$_x$), some other FBN-s discussed here may do. In the\npresent work, fluorene, oxygen and combined oxygen and boron trifluoride\nfunctionalizations are studied, on the basis of band structure calculations.\nDue to the open surfaces of FBN-s, fast ionic diffusion with Li, Na and Mg ions\nis possible, enabling batteries with voltages of 2.1-5.6 V, theoretical energy\ndensities of 800-1200 Wh/kg and fast charge and discharge.",
        "positive": "Static and Dynamic Disorder in Formamidinium Lead Bromide Single\n  Crystals: We show that formamidinium lead bromide is unique among the halide perovskite\ncrystals because its inorganic sub-lattice exhibits intrinsic local static\ndisorder that co-exists with a well-defined average crystal structure. Our\nstudy combines THz-range Raman-scattering with single-crystal X-ray diffraction\nand first-principles calculations to probe the inorganic sub-lattice dynamics\nevolution with temperature in the range of 10-300 K. The temperature evolution\nof the Raman spectra shows that low-temperature, local static disorder strongly\naffects the crystal's structural dynamics and phase transitions at higher\ntemperatures."
    },
    {
        "anchor": "A two-component model of the neutron diffuse scattering in the relaxor\n  ferroelectric PZN-4.5%PT: We report measurements of the neutron diffuse scattering in a single crystal\nof the relaxor ferroelectric material\n95.5%Pb(Zn$_{1/3}$Nb$_{2/3}$)O$_3$-4.5%PbTiO$_3$ (PZN-4.5%PT). Our results\nsuggest that the nanometer scale structure in this compound exhibits both\n$<100>$ and $<110>$ polarizations, which contribute to different portions of\nthe total diffuse scattering intensity. These contributions can be\ndistinguished by the differing responses to an electric field applied along\n[001]. While diffuse scattering intensities associated with $<110>$ (T2-type)\npolarizations show little to no change in a [001] field, those associated with\n$<100>$ (T1-type) polarizations are partially suppressed by the field at\ntemperatures below the Curie temperature \\emph{T$_C$} $\\sim 475$ K. Neutron\nspin-echo measurements show that the diffuse scattering at (0.05,0,1) is\nlargely dynamic at high temperature and gradually freezes on cooling, becoming\nmostly static at 200 K.",
        "positive": "Expanded stability of layered SnSe-PbSe alloys and evidence of\n  displacive phase transformation from rocksalt in heteroepitaxial thin films: Bulk PbSnSe has a two-phase region or miscibility gap as the crystal changes\nfrom a Van der Waals-bonded orthorhombic 2D layered structure in SnSe-rich\ncompositions to the related 3D-bonded rocksalt structure in PbSe-rich\ncompositions with large contrast in the electrical, optical, and thermal\nproperties across this transition. With an aim to understand and harness this\ntransition in thin films devices, we epitaxially integrate PbSnSe on GaAs by\nmolecular beam epitaxy using an in-situ PbSe surface treatment and show a\nsignificantly reduced two-phase region by stabilizing the Pnma layered\nstructure out to Pb$_{0.45}$Sn$_{0.55}$Se, beyond the bulk-limit of\nPb$_{0.25}$Sn$_{0.75}$Se. Pushing further, we directly access metastable\ntwo-phase epitaxial films of layered and rocksalt grains that are nearly\nidentical in composition around Pb$_{0.5}$Sn$_{0.5}$Se and entirely circumvent\nthe miscibility gap. We present microstructural evidence for an incomplete\ndisplacive transformation from rocksalt to layered structure in these films\nthat we speculate occurs during the sample cool down to room temperature after\nsynthesis. In-situ x-ray diffraction measurement of an as-grown\nPb$_{0.56}$Sn$_{0.44}$Se rocksalt film under cryogenic cooling reproduces the\nkey attributes of this transition and validates our hypothesis. Notably, we\nfind well-defined orientation relationships between the phases forming in the\nprocess and unconventional strain-relief mechanisms involved in the crystal\nstructure transformation by transmission electron microscopy. Overall, our work\nadds a scalable thin film integration route to harnessing metastable layered\ncompositions as well as the dramatic contrast in material properties in PbSnSe\nacross a potentially ultrafast structural transition."
    },
    {
        "anchor": "Spatial distribution functions of random packed granular spheres\n  obtained by direct particle imaging: We measure the two-point density correlations and Voronoi cell distributions\nof cyclically sheared granular spheres obtained with a fluorescence technique\nand compare them with random packing of frictionless spheres. We find that the\nradial distribution function $g(r)$ is captured by the Percus-Yevick equation\nfor initial volume fraction $\\phi=0.59$. However, small but systematic\ndeviations are observed because of the splitting of the second peak as $\\phi$\nis increased towards random close packing. The distribution of the Voronoi free\nvolumes deviates from postulated $\\Gamma$ distributions, and the orientational\norder metric $Q_6$ shows disorder compared to numerical results reported for\nfrictionless spheres. Overall, these measures show significant similarity of\nrandom packing of granular and frictionless spheres, but some systematic\ndifferences as well.",
        "positive": "Premartensitic Transition in Ni2+xMn1-xGa Heusler Alloys: The temperature dependencies of the resistivity and magnetization of a series\nof Ni2+XMn1-XGa (X = 0 - 0.09) alloys were investigated. Along with the\nanomalies associated with ferromagnetic and martensitic transitions,\nwell-defined anomalies were observed at the temperature of premartensitic\ntransformation. The premartensitic phase existing in a temperature range 200 -\n260 K in the stoichiometric Ni2MnGa is suppressed by the martensitic phase with\nincreasing Ni content and vanishes in Ni2.09Mn0.91Ga composition."
    },
    {
        "anchor": "Quasiparticle Chirality in Epitaxial Graphene Probed at the Nanometer\n  Scale: Graphene exhibits unconventional two-dimensional electronic properties\nresulting from the symmetry of its quasiparticles, which leads to the concepts\nof pseudospin and electronic chirality. Here we report that scanning tunneling\nmicroscopy can be used to probe these unique symmetry properties at the\nnanometer scale. They are reflected in the quantum interference pattern\nresulting from elastic scattering off impurities, and they can be directly read\nfrom its fast Fourier transform. Our data, complemented by theoretical\ncalculations, demonstrate that the pseudospin and the electronic chirality in\nepitaxial graphene on SiC(0001) correspond to the ones predicted for ideal\ngraphene.",
        "positive": "Understanding the Interface Dipole of Copper Phthalocyanine (CuPc)/C60:\n  Theory and Experiment: Interface dipole determines the electronic energy alignment in donor/acceptor\ninterfaces and plays an important role in organic photovoltaics. Here we\npresent a study combining first principles density functional theory (DFT) with\nultraviolet photoemission spectroscopy (UPS) and time-of-flight secondary ion\nmass spectrometry (TOF-SIMS) to investigate the interface dipole, energy level\nalignment, and structural properties at the interface between CuPc and C60. DFT\nfinds a sizable interface dipole for the face-on orientation, in quantitative\nagreement with the UPS measurement, and rules out charge transfer as the origin\nof the interface dipole. Using TOF-SIMS we show that the interfacial morphology\nfor the bilayer CuPc/C60 film is characterized by molecular intermixing,\ncontaining both the face-on and the edge-on orientation. The complementary\nexperimental and theoretical results provide both insight into the origin of\nthe interface dipole and direct evidence for the effect of interfacial\nmorphology on the interface dipole."
    },
    {
        "anchor": "Modulation of a surface plasmon-polariton resonance by sub-terahertz\n  diffracted coherent phonons: Coherent sub-THz phonons incident on a gold grating that is deposited on a\ndielectric substrate undergo diffraction and thereby induce an alteration of\nthe surface plasmon-polariton resonance. This results in efficient\nhigh-frequency modulation (up to 110 GHz) of the structure's reflectivity for\nvisible light in the vicinity of the plasmon-polariton resonance. High\nmodulation efficiency is achieved by designing a periodic nanostructure which\nprovides both plasmon-polariton and phonon resonances. Our theoretical analysis\nshows that the dynamical alteration of the plasmon-polariton resonance is\ngoverned by modulation of the slit widths within the grating at the frequencies\nof higher-order phonon resonances.",
        "positive": "Thermal conductivity of PbTe-CoSb3 bulk polycrystalline composite: the\n  role of microstructure and interface thermal resistance: Systematic experimental and theoretical research on the role of\nmicrostructure and interface thermal resistance on the thermal conductivity of\nthe PbTe-CoSb3 bulk polycrystalline composite is presented. In particular, the\ncorrelation between the particle size of the dispersed phase and interface\nthermal resistance (R_{int}) on the phonon thermal conductivity (\\kappa_{ph})\nis discussed. With this aim, a series of PbTe-CoSb_3 polycrystalline composite\nmaterials with the different particle sizes of CoSb_3 was prepared. The\nstructural (XRD) and microstructural analysis (SEM/EDXS) confirmed assumed\nchemical and phase compositions. The acoustic impedance difference (\\Delta Z)\nwas determined from measured sound velocities in PbTe and CoSb_3 phases. The\ninterface thermal resistance (R_{int}) was calculated using the Debye model and\nagrees with the experimental R_{int}. It is shown that the \\kappa_{ph} of the\ncomposite may be reduced when the particle size of the dispersed phase (CoSb_3)\nis smaller than the critical value of ~230nm. This relationship was concluded\nto be crucial for controlling the heat transport phenomena in composite\nthermoelectric materials. The selection of the components with different\nelastic properties (acoustic impedance) and particle size smaller than the\nKapitza radius leads to a new direction in the engineering of composite TE\nmaterials with designed thermal properties"
    },
    {
        "anchor": "Nonlinear magnetoelastic behavior of the metastable bcc phases Co and\n  Ni: Importance of third-order contributions for bcc Ni: The first- and second-order magnetoelastic coefficients of the metastable bcc\nphases Co and Ni are calculated by using a combination of the phenomenological\ntheory of nonlinear magnetoelasticity with the ab-initio density functional\nelectron theory. The magnetoelastic behavior of the bcc phases is drastically\ndifferent from that of the corresponding fcc phases. The recently synthesized\nbcc phase of Ni appears to be an example of a material for which third-order\nmagnetoelastic effects are essential.",
        "positive": "Image of Veselago lens based upon two-dimensional photonic crystal with\n  triangular lattice: The construction of the multi-focal Veselago lens predicted earlier is\nproposed on the basis of a uniaxial photonic crystal consisting of cylindrical\nair holes in silicon that make a triangular lattice in a plane perpendicular to\nthe axis of the crystal. The object and image are in air. The period of the\ncrystal should be $0.44\\mu{\\rm m}$ to work at the wavelength $1.5\\mu{\\rm m}$.\nThe lens does not provide superlensing but the half-width of the image is\n$0.5\\lambda$. The lens is shown to have wave guiding properties depending on\nthe substrate material."
    },
    {
        "anchor": "Carrier concentration dependence of optical Kerr nonlinearity in indium\n  tin oxide films: Optical Kerr nonlinearity (n2) in n-type indium tin oxide (ITO) films coated\non glass substrates has been measured using Z-scans with 200-fs laser pulses at\nwavelengths ranging from 720 to 780 nm. The magnitudes of the measured\nnonlinearity in the ITO films were found to be dependent on the carrier\nconcentration with a maximum n2-value of 4.1 x 10-5 cm2/GW at 720-nm wavelength\nand an electron density of Nd = 5.8 x 1020 cm-3. The Kerr nonlinearity was also\nobserved to be varied with the laser wavelength. By employing a femtosecond\ntime-resolved optical Kerr effect (OKE) technique, the relaxation time of OKE\nin the ITO films is determined to be ~1 ps. These findings suggest that the\nKerr nonlinearity in ITO can be tailored by controlling the carrier\nconcentration, which should be highly desirable in optoelectronic devices for\nultrafast all-optical switching.",
        "positive": "Raman microscopy as a defect microprobe for hydrogen bonding\n  characterization in materials used in fusion applications: We present the Raman microscopy ability to detect and characterize the way\nhydrogen is bonded with elements that will be used for ITER's plasma facing\ncomponents. For this purpose we first use hydrogenated amorphous carbon\nsamples, formed subsequently to plasma-wall interactions (hydrogen\nimplantation, erosion, deposition...) occurring inside tokamaks, to demonstrate\nhow this technique can be used to retrieve useful information. We pay attention\nin identifying which spectroscopic parameters are sensitive to the local\nstructure (sp 3 /sp 2) and which gives information on the hydrogen content\nusing isothermal and linear temperature ramp studies on reference samples\nproduced by plasma enhanced chemical vapor deposition. We then focus on the\npossibility to use this fast, non-destructive and non-contact technique to\ncharacterize the influence of hydrogen isotope implantation in few nanometers\nof graphite and beryllium as C is still used in the JT-60 tokamak and Be is\nused in JET and will be used as plasma-facing component in the future reactor\nITER. We also pay attention on implantation in tungsten oxide which may be\nformed accidently in the machine."
    },
    {
        "anchor": "Fast electrochemical doping due to front instability in organic\n  semiconductors: The electrochemical doping transformation in organic semiconductor devices is\nstudied in application to light-emitting cells. It is shown that the device\nperformance can be significantly improved by utilizing new fundamental\nproperties of the doping process. We obtain an instability, which distorts the\ndoping fronts and increases the doping rate considerably. We explain the\nphysical mechanism of the instability, develop theory, provide experimental\nevidence, and perform numerical simulations. We further show how improved\ndevice design can amplify the instability thus leading to a much faster doping\nprocess and device kinetics.",
        "positive": "Steepest-Entropy-Ascent Quantum Thermodynamics Models in Materials\n  Science: Steepest-entropy-ascent quantum thermodynamics, or SEAQT, is a unified\napproach of quantum mechanics and thermodynamics that avoids many of the\ninconsistencies that can arise between the two theories. Given a set of energy\nlevels, i.e., energy eigenstructure, accessible to a given physical system,\nSEAQT predicts the unique kinetic path from any initial non-equilibrium state\nto stable equilibrium by solving a master equation that directs the system\nalong the path of steepest entropy ascent. There are no intrinsic limitations\non the length and time scales the method can treat so it is well-suited for\ncalculations where the dynamics over multiple spacial scales need to be taken\ninto account within a single framework. In this paper, the theoretical\nframework and its advantages are described, and several applications are\npresented to illustrate the use of the SEAQT equation of motion and the\nconstruction of a simplified, reduced-order, energy eigenstructure."
    },
    {
        "anchor": "A consistent picture of excitations in cubic BaSnO$_{3}$ revealed by\n  combining theory and experiment: Among the transparent conducting oxides, the perovskite barium stannate is\nmost promising for various electronic applications due to its outstanding\ncarrier mobility achieved at room temperature. However, most of its important\ncharacteristics, such as band gaps, effective masses, and absorption edge,\nremain controversial. Here, we provide a fully consistent picture by combining\nstate-of-the-art {\\it ab initio} methodology with forefront electron\nenergy-loss spectroscopy and optical absorption measurements. Valence electron\nenergy-loss spectra, featuring signals originating from band gap transitions,\nare acquired on defect-free sample regions of a BaSnO$_{3}$ single crystal.\nThese high-energy-resolution measurements are able to capture also very weak\nexcitations below the optical gap, attributed to indirect transitions. By\ntemperature-dependent optical absorption measurements, we assess band-gap\nrenormalization effects induced by electron-phonon coupling. Overall, we find\nfor the effective electronic mass, the direct and the indirect gap, the optical\ngap, as well as the absorption onsets and spectra, excellent agreement between\nboth experimental techniques and the theoretical many-body results, supporting\nalso the picture of a phonon-mediated mechanism where indirect transitions are\nactivated by phonon-induced symmetry lowering. This work demonstrates a\nfruitful connection between different high-level theoretical and experimental\nmethods for exploring the characteristics of advanced materials.",
        "positive": "Photocatalytic H2 generation using dewetted Pt-decorated TiO2 nanotubes\n  - Optimized dewetting and oxide crystallization by a multiple annealing\n  process: In the present work we use TiO2 nanotube arrays, carrying a Pt coating that\nis optimally dewetted, as a photocatalyst to generate H2. In order to achieve a\nmaximum H2-generation efficiency, on the one hand an ideal thermal dewetting of\nthe Pt layer into nanoparticles is needed that requires an oxygen free heat\ntreatment, and on the other hand an optimal crystallization of the TiO2\nnanotubes into anatase with reduced defect density is achieved only by\nannealing in O2 containing environment. To overcome this issue, we combine\nadequate reducing and oxidizing conditions in a multiple annealing treatment,\nand obtain Pt-decorated anatase TiO2 nanotubes showing significantly enhanced\nphotocatalytic H2 generation ability."
    },
    {
        "anchor": "Hidden phase uncovered by ultrafast carrier dynamics in thin Bi2O2Se: Bi2O2Se has attracted intensive attention due to its potential in\nelectronics, optoelectronics, as well as ferroelectric applications. Despite\nthat, there have only been a handful of experimental studies based on ultrafast\nspectroscopy to elucidate the carrier dynamics in Bi2O2Se thin films, Different\ngroups have reported various ultrafast timescales and associated mechanisms\nacross films of different thicknesses. A comprehensive understanding in\nrelation to thickness and fluence is still lacking. In this work, we have\nsystematically explored the thickness-dependent Raman spectroscopy and\nultrafast carrier dynamics in chemical vapor deposition (CVD)-grown Bi2O2Se\nthin films on mica substrate with thicknesses varying from 22.44 nm down to\n4.62 nm at both low and high pump fluence regions. Combining the thickness\ndependence and fluence dependence of the slow decay time, we demonstrate a\nferroelectric transition in the thinner (< 8 nm) Bi2O2Se films, influenced by\nsubstrate-induced compressive strain and non-equilibrium states. Moreover, this\ntransition can be manifested under highly non-equilibrium states. Our results\ndeepen the understanding of the interplay between the ferroelectric phase and\nsemiconducting characteristics of Bi2O2Se thin films, providing a new route to\nmanipulate the ferroelectric transition.",
        "positive": "Joule Heating and Current-Induced Instabilities in Magnetic Nanocontacts: We consider the electrical current through a magnetic point contact in the\nlimit of a strong inelastic scattering of electrons. In this limit local Joule\nheating of the contact region plays a decisive role in determining the\ntransport properties of the point contact. We show that if an applied constant\nbias voltage exceeds a critical value, the stationary state of the system is\nunstable, and that periodic, non-harmonic oscillations in time of both the\nelectrical current through the contact and the local temperature in the contact\nregion develop spontaneously. Our estimations show that the necessary\nexperimental conditions for observing such oscillations with characteristic\nfrequencies in the range $10^8 \\div 10^9$ Hz can easily be met. We also show a\npossibility to manipulate upon the magnetization direction of a magnetic grain\ncoupled through a point contact to a bulk ferromagnetic by exciting the\nabove-mentioned thermal-electric oscillations."
    },
    {
        "anchor": "Thermoelectric Studies of Nanoporous Thin Films with Adjusted Pore-Edge\n  Charges: In recent years, nanoporous thin films have been widely studied for\nthermoelectric applications. High thermoelectric performance is reported for\nnanoporous Si films, which is attributed to the dramatically reduced lattice\nthermal conductivity and bulk-like electrical properties. Porous materials can\nalso be used in gas sensing applications by engineering the surface-trapped\ncharges on pore edges. In this work, an analytical model is developed to\nexplore the relationship between the thermoelectric properties and pore-edge\ncharges in a periodic two-dimensional nanoporous material. The presented model\ncan be widely used to analyze the measured electrical properties of general\nnanoporous thin films and two-dimensional materials.",
        "positive": "Theory of nonlinear optical properties of phenyl-substituted\n  polyacetylenes: In this paper we present a theoretical study of the third-order nonlinear\noptical properties of poly(diphenyl)polyacetylene (PDPA) pertaining to the\nthird-harmonic-generation (THG) process. We study the aforesaid process in\nPDPA's using both the independent electron Hueckel model, as well as\ncorrelated-electron Pariser-Parr-Pople (P-P-P) model. The P-P-P model based\ncalculations were performed using various configuration interaction (CI)\nmethods such as the the multi-reference-singles-doubles CI (MRSDCI), and the\nquadruples-CI (QCI) methods, and the both longitudinal and the transverse\ncomponents of third-order susceptibilities were computed. The Hueckel model\ncalculations were performed on oligo-PDPA's containing up to fifty repeat\nunits, while correlated calculations were performed for oligomers containing up\nto ten unit cells. At all levels of theory, the material exhibits highly\nanisotropic nonlinear optical response, in keeping with its structural\nanisotropy. We argue that the aforesaid anisotropy can be divided over two\nnatural energy scales: (a) the low-energy response is predominantly\nlongitudinal and is qualitatively similar to that of polyenes, while (b) the\nhigh-energy response is mainly transverse, and is qualitatively similar to that\nof trans-stilbene."
    },
    {
        "anchor": "Room temperature structure and energetics of water-hydroxyl layers on\n  Pt(111): The interactions between water and hydroxyl species on Pt(111) surfaces have\nbeen intensely investigated due to their importance to fuel cell\nelectrocatalysis. Here we present a room temperature molecular dynamics study\nof their structure and energetics using an ensemble of neural network\npotentials, which allow us to obtain unprecedented statistical sampling. We\nfirst study the energetics of hydroxyl formation, where we find a near-linear\nadsorption energy profile, which exhibits a soft and gradual increase in the\ndifferential adsorption energy at high hydroxyl coverages. This is strikingly\ndifferent from the predictions of the conventional bilayer model, which\ndisplays a kink at 1/3ML OH coverage indicating a sizeable jump in differential\nadsorption energy, but within the statistical uncertainty of previously\nreported ab initio molecular dynamics studies. We then analyze the structure of\nthe interface, where we provide evidence for the water-OH/Pt(111) interface\nbeing hydrophobic at high hydroxyl coverages. We furthermore explain the\nobserved adsorption energetics by analyzing the hydrogen bonding in the\nwater-hydroxyl adlayers, where we argue that the increase in differential\nadsorption energy at high OH coverage can be explained by a reduction in the\nnumber of hydrogen bonds from the adsorbed water molecules to the hydroxyls.",
        "positive": "Electron-phonon Coupling on the Surface of the Topological Insulator\n  Bi2Se3: Determined from Surface Phonon Dispersion Measurements: In this letter we report measurements of the coupling between Dirac fermion\nquasiparticles (DFQs) and phonons on the (001) surface of the strong\ntopological insulator Bi2Se3. While most contemporary investigations of this\ncoupling have involved examining the temperature dependence of the DFQ\nself-energy via angle-resolved photoemission spectroscopy (ARPES) measurements,\nwe employ inelastic helium atom scattering to explore, for the first time, this\ncoupling from the phonon perspective. Using a Hilbert transform, we are able to\nobtain the imaginary part of the phonon self-energy associated with a\ndispersive surface phonon branch identified in our previous work [1] as having\nstrong interactions with the DFQs. From this imaginary part of the self-energy\nwe obtain a branch-specific electron-phonon coupling constant of 0.43, which is\nstronger than the values reported form the ARPES measurements."
    },
    {
        "anchor": "Anomalous thermal conductivity and suppression of negative thermal\n  expansion in ScF3: The empty perovskite ScF3 exhibits negative thermal expansion up to 1100 K.\nWe demonstrate that ab-initio calculations of temperature-dependent effective\nphonon spectra allow to quantitatively describe the behavior of this compound\nand the suppression of negative thermal expansion. Based on this result, we\npredict an anomalous temperature dependence of the thermal conductivity and\ninterpret it as a general feature of the perovskite class. Finally, we comment\non the fact that the suppression of negative thermal expansion at such a high\ntemperature is beyond the reach of the quasi-harmonic approximation and we\ndiscuss this suppression based on the temperature-dependence of the mode\nGr\\\"uneisen parameters.",
        "positive": "Are fluorinated BN nanotubes n-type semiconductors?: The structural and electronic properties of fluorine (F)-doped BN nanotubes\n(BNNTs) are studied using density functional methods. Our results indicate that\nF atoms prefer to substitute N atoms, resulting in substantial changes of BN\nlayers. However, F substitutional doping results in no shallow impurity states.\nThe adsorption of F atoms on B sites is more stable than that on N sites. BNNTs\nwith adsorbed F atoms are p-type semiconductors, suggesting the electronic\nconduction in F-doped multiwalled BNNTs with large conductivity observed\nexperimentally might be of p-type due to the adsorbed F atoms, but not n-type\nas supposed before."
    },
    {
        "anchor": "Hybrid Electrothermal Simulation of a Three-Dimensional Fin-Shaped\n  Field-Effect Transistor Based on GaN Nanowires: In recent years, three-dimensional GaN-based transistors have been\nintensively studied for their dramatically improved output power, better gate\ncontrollability, and shorter channels for speedup and miniaturization. However,\nthermal analysis of such devices is often oversimplified using the conventional\nFourier's law and bulk material properties in thermal simulations. In this\naspect, accurate temperature predictions can be achieved by coupled phonon and\nelectron Monte Carlo simulations that track the movement and scattering of\nindividual phonons and electrons. However, the heavy computational load often\nrestricts such simulations to nanoscale devices, while a real chip is of\nmillimeter to centimeter sizes. This issue can be addressed by a hybrid\nsimulation technique that employs the Fourier's law for regions away from the\nhot spot. Using this technique, accurate electrothermal simulations are carried\nout on a nanowire-based GaN transistor to reveal the temperature rise in such\ndevices.",
        "positive": "On the bridge hypothesis in the glass transition of freestanding polymer\n  films: Freestanding thin polymer films with high molecular weights exhibit an\nanomalous decrease in the glass-transition temperature with film thickness.\nSpecifically, in such materials, the measured glass-transition temperature\nevolves in an affine way with the film thickness, with a slope that weakly\ndepends on the molecular weight. De Gennes proposed a sliding mechanism as the\nhypothetical dominant relaxation process in these systems, where stress kinks\ncould propagate in a reptation-like fashion through so called bridges, i.e.\nfrom one free interface to the other along the backbones of polymer\nmacromolecules. Here, by considering the exact statistics of finite-sized\nrandom walks within a confined box, we investigate in details the bridge\nhypothesis. We show that the sliding mechanism cannot reproduce the basic\nfeatures appearing in the experiments, and we exhibit the fundamental reasons\nbehind such a fact."
    },
    {
        "anchor": "Helium bubbles in liquid lithium: a potential issue for ITER: Future fusion nuclear reactors will produce sustainable energy form the\nfusion of deuterium and tritium. In order to do so, the reactors will need to\nproduce their own tritium through the neutron bombardment of lithium. Such\nreaction will produce tritium and helium inside the breeding blanket of the\nreactor. Helium can trigger nucleation mechanisms due to its very low\nsolubility inside liquid metals. Consequently, the knowledge and understanding\nof the microscopic processes of helium nucleation is crucial to improve the\nefficiency, sustainability and safety of the fusion energy production. The\nformation of helium bubbles inside the liquid metal used as breeding material\nmay be a serious issue that has yet to be fully understood. We provide further\ninsight on the behavior of lithium and helium mixtures at experimentally\ncorresponding operating conditions (800~K and pressures between 1 and 100 bar)\nusing a suitable microscopic model able to describe the helium and lithium\natomic interactions, in excellent agreement with available experimental data.\nThe simulations predict the formation of helium bubbles with radii around 10\nAngstroem at ambient pressure and with surface tension values between 0.6-1.0\nN/m, with a dependency of the concentration of helium. We also report cohesive\nenergies of helium as well as a quantitative estimation of the Hildebrand and\nKumar cohesion parameters.",
        "positive": "Rapid appearance of domains upon phase change in KNbO3 - a TEM in-situ\n  heating study: TEM specimens from potassium niobate single crystals were observed while\nbeing heated in a TEM. DWs and dislocations were observed; the DWs were mobile.\nIn certain cases the DWs became pinned by the dislocations, at least for a\nshort time, most likely due to interaction of strain fields. Both phase changes\nwere observed with accompanying rapid appearance of new domain patterns."
    },
    {
        "anchor": "Spin Gapless Semiconducting Nature in Co-rich Co1+xFe1-xCrGa: Insight\n  and Advancements: In this report, we present structural, electronic, magnetic and transport\nproperties of Co-rich spin gapless semiconductor CoFeCrGa using both\ntheoretical and experimental techniques. The key advantage of Co-rich samples\n$\\mathrm{Co_{1+x}Fe_{1-x}CrGa}$ is the high Curie temperature (T$\\mathrm{_C}$)\nand magnetization, without compromising the SGS nature (up to x = 0.4), and\nhence our choice. The quaternary Heusler alloys $\\mathrm{Co_{1+x}Fe_{1-x}CrGa}$\n(x = 0.1 to 0.5) are found to crystallize in LiMgPdSn-type structure having\nspace group $F\\bar{4}3m$ (\\# 216). The measured Curie temperature increases\nfrom 690 K (x = 0) to 870 K (x = 0.5). Observed magnetization values follow the\nSlater-Pauling rule. Measured electrical resistivity, in the temperature range\nof 5-350 K, suggests that the alloys retain the SGS behavior up to x = 0.4,\nbeyond which it reflects metallic character. Unlike conventional\nsemiconductors, the conductivity value ($\\mathrm{\\sigma_{xx}}$) at 300 K lies\nin the range of 2289 S $\\mathrm{cm^{-1}}$ to 3294 S $\\mathrm{cm^{-1}}$, which\nis close to that of other reported SGS materials. The anomalous Hall effect is\ncomparatively low. The intrinsic contribution to the anomalous Hall\nconductivity increase with x, which can be correlated with the enhancement in\nchemical order. The anomalous Hall coefficient is found to increase from 38\nS/cm for x = 0.1 to 43 S/cm for 0.3. Seebeck coefficients turn out to be\nvanishingly small below 300 K, another signature for being SGS. All the alloys\n(for different x) are found to be both chemically and thermally stable.\nSimulated magnetization agrees fairly with the experiment. As such Co-rich\nCoFeCrGa is a promising candidate for room temperature spintronic applications,\nwith enhanced T$\\mathrm{_C}$, magnetic properties and SGS nature.",
        "positive": "Two-dimensional Quasi-Freestanding Molecular Crystals for\n  High-Performance Organic Field-Effect Transistors: Two-dimensional atomic crystals are extensively studied in recent years due\nto their exciting physics and device applications. However, a molecular\ncounterpart, with scalable processability and competitive device performance,\nis still challenging. Here, we demonstrate that high-quality few-layer\ndioctylbenzothienobenzothiophene molecular crystals can be grown on graphene or\nboron nitride substrate via van der Waals epitaxy, with precisely controlled\nthickness down to monolayer, large-area single crystal, low process temperature\nand patterning capability. The crystalline layers are atomically smooth and\neffectively decoupled from the substrate due to weak van der Waals\ninteractions, affording a pristine interface for high-performance organic\ntransistors. As a result, monolayer dioctylbenzothienobenzothiophene molecular\ncrystal field-effect transistors on boron nitride show record-high carrier\nmobility up to 10cm2V-1s-1 and aggressively scaled saturation voltage around\n1V. Our work unveils an exciting new class of two-dimensional molecular\nmaterials for electronic and optoelectronic applications."
    },
    {
        "anchor": "Solid-state laser refrigeration of nanodiamond quantum sensors: The negatively-charged nitrogen vacancy (NV$^-$) centre in diamond is a\nremarkable optical quantum sensor for a range of applications including,\nnanoscale thermometry, magnetometry, single photon generation, quantum\ncomputing, and communication. However, to date the performance of these\ntechniques using NV$^-$ centres has been limited by the thermally-induced\nspectral wandering of NV$^-$ centre photoluminescence due to detrimental\nphotothermal heating. Here we demonstrate that solid-state laser refrigeration\ncan be used to enable rapid (ms) optical temperature control of nitrogen\nvacancy doped nanodiamond (NV$^-$:ND) quantum sensors in both atmospheric and\n\\textit{in vacuo} conditions. Nanodiamonds are attached to ceramic\nmicrocrystals including 10\\% ytterbium doped yttrium lithium fluoride\n(Yb:LiYF$_4$) and sodium yttrium fluoride (Yb:NaYF$_4$) by van der Waals\nbonding. The fluoride crystals were cooled through the efficient emission of\nupconverted infrared photons excited by a focused 1020 nm laser beam. Heat\ntransfer to the ceramic microcrystals cooled the adjacent NV$^-$:NDs by 10 and\n27 K at atmospheric pressure and $\\sim$10$^{-3}$ Torr, respectively. The\ntemperature of the NV$^-$:NDs was measured using both Debye-Waller factor (DWF)\nthermometry and optically detected magnetic resonance (ODMR), which agree with\nthe temperature of the laser cooled ceramic microcrystal. Stabilization of\nthermally-induced spectral wandering of the NV$^{-}$ zero-phonon-line (ZPL) is\nachieved by modulating the 1020 nm laser irradiance. The demonstrated cooling\nof NV$^-$:NDs using an optically cooled microcrystal opens up new possibilities\nfor rapid feedback-controlled cooling of a wide range of nanoscale quantum\nmaterials.",
        "positive": "Free-carrier screening of polarization fields in wurtzite GaN/InGaN\n  laser structures: The free-carrier screening of macroscopic polarization fields in wurtzite\nGaN/InGaN quantum wells lasers is investigated via a self-consistent\ntight-binding approach. We show that the high carrier concentrations found\nexperimentally in nitride laser structures effectively screen the built-in\nspontaneous and piezoelectric polarization fields, thus inducing a\n``field-free'' band profile. Our results explain some heretofore puzzling\nexperimental data on nitride lasers, such as the unusually high lasing\nexcitation thresholds and emission blue-shifts for increasing excitation\nlevels."
    },
    {
        "anchor": "Free-carrier relaxation and lattice heating in photoexcited bismuth thin\n  films: We report ultrafast surface pump and interface probe experiments on\nphotoexcited carrier transport across single crystal bismuth films on sapphire.\nThe film thickness is sufficient to separate carrier dynamics from lattice\nheating and strain, allowing us to investigate the time-scales of momentum\nrelaxation, heat transfer to the lattice and electron-hole recombination. The\nmeasured electron-hole ($e-h$) recombination time is 12--26 ps and ambipolar\ndiffusivity is 18--40 cm$^{2}$/s for carrier excitation up to $\\sim 10^{19}\n\\text{cm}^{-3}$. By comparing the heating of the front and back sides of the\nfilm, we put lower limits on the rate of heat transfer to the lattice, and by\nobserving the decay of the plasma at the back of the film, we estimate the\ntimescale of electron-hole recombination. We interpret each of these timescales\nwithin a common framework of electron-phonon scattering and find qualitative\nagreement between the various relaxation times observed. We find that the\ncarrier density is not determined by the $e-h$ plasma temperature after a few\npicoseconds. The diffusion and recombination become nonlinear with initial\nexcitation $\\gtrsim 10^{20} \\text{cm}^{-3}$.",
        "positive": "Statistical Models of the Polaronic Phase Transition in Manganites: We propose two statistical models for description the metal-insulator phase\ntransition coupled with paramagnetic-ferromagnetic phase transition in\nmanganites of the type La_{1-x}Sr_xMnO_3. The first one based on the\ncompetition of small polarons and delocalized carriers. In the second one the\nconductivity appears as a result of overlapping of large polarons. We compare\nour models with the experimental data."
    },
    {
        "anchor": "Diffusion in LanCoIn3n+2 phases studied by perturbed angular correlation: Jump frequencies of 111In/Cd tracer atoms were measured for a series of\nlayered phases LanCoIn3n+2 using the technique of perturbed angular correlation\nof gamma rays (PAC). The frequencies were determined by analysis of nuclear\nquadrupole relaxation produced by fluctuating electric field gradients. Samples\nwere synthesized having nominal values n= 1, 2, 3, 5 and \\infty, with n=\\infty\ncorresponding to the L12 phase LaIn3. The phases form heuristically from LaIn3\nby replacing every (n+1)th (100) mixed plane of La and In atoms with a plane of\nCo-atoms. For the n=1 phase, LaCoIn5, jump frequencies were too small to\ndetect. Two signals were observed, one for indium atoms next to the Co-planes\nand the other for more distant indium atoms. No relaxation was observed for\natoms next to the Co-planes, indicating that there is no diffusion across the\nCo-planes. With increasing n, jump rates for the other In-atoms increased\ntoward values observed for LaIn3. Jump frequency activation enthalpies for n= 3\nand 5 were observed to be the same as for n=\\infty, suggesting the same\ndiffusion mechanism. However, the jump-frequency prefactors were found to be\nsmaller for small n, which is attributed to reductions in the connectivity of\nthe diffusion sublattice. We conclude that diffusion in the layered phases is\nremarkably similar to diffusion in LaIn3 once the reduced connectivity is taken\ninto account.",
        "positive": "Computational study of the structural, electronic and optical properties\n  of bulk palladium nitrides: The atomic and electronic structures of Pd3N, PdN and PdN2 were investigated\nusing ab initio density-functional theory (DFT). We studied cohesive energy vs.\nvolume equation of states (EOS) for a set of reported and hypothetical\nstructures. Obtained data was fitted to a third-order Birch-Murnaghan equation\nof state (EOS) so as to identify the energetically most stable phases and to\ndetermine their equilibrium structural parameters and stability and mechanical\nproperties. Electronic properties were investigated by calculating the band\ndiagrams and the total and partial density of states (DOS). Some possible\npressure-induced phase transitions were tested. To derive the\nfrequency-dependent optical spectra (i.e. absorption coefficient, reflectivity,\nrefractive index, and energy-loss), we performed G_0W0 calculations within the\nrandom-phase approximation (RPA) to the dielectric tensor. Obtained results\nwere compared with previous studies."
    },
    {
        "anchor": "Dynamic motion of polar skyrmions in oxide heterostructures: Polar skyrmions have been widely investigated in oxide heterostructure\nrecently, due to their exotic properties and intriguing physical insights.\nMeanwhile, so far, the external field-driven motion of the polar skyrmion, akin\nto the magnetic counterpart, has yet to be discovered. Here, using phase-field\nsimulations, we demonstrate the dynamic motion of the polar skyrmions with\nintegrated external thermal, electrical, and mechanical stimuli. The external\nheating reduces the spontaneous polarization hence the skyrmion motion barrier,\nwhile the skyrmions shrink under the electric field, which could weaken the\nlattice pinning and interactions between the skyrmions. The mechanical force\ntransforms the skyrmions into c-domain in the vicinity of the indenter center\nunder the electric field, providing the space and driving force needed for the\nskyrmions to move. This study confirmed that the skyrmions are quasi-particles\nthat can move collectively, while also providing concrete guidance for the\nfurther design of polar skyrmion-based electronic devices.",
        "positive": "On the room-temperature aging effects in YBa2Cu3O6+d: The aging effects in YBa2Cu3O6+d have been investigated on the low-speed\nquenched samples in contrast to other similar studies where the high-speed\nquenched samples were examined. In the framework of the investigation, XPS\nanalysis has been conducted for the samples stored after quenching for the\nspecified times t and a detailed experimental dependence of the YBa2Cu3O6+d\nlattice parameters a, b, and c on both d and t has been obtained. The regime of\nlow-speed quenching results in a threefold increase in the aging effect\nmagnitude. Particular cases of the c(d; t) dependence are well described by a\nsecond-order polynomial with applying different coefficients for different t.\nThe behavior c has been explained on the basis of a simple model of the Coulomb\ninteraction between the CuO2 and CuOd structural planes, in which the hole\ncharge transfer from CuOd to CuO2 takes place providing the standard level of\nTc in YBa2Cu3O6+d (this level is characterized by a maximum Tc of 93 K at d =\n0.9). It has been demonstrated that the c(d; t) dependence is a good\nalternative to assessing the hole concentration in YBa2Cu3O6+d. By analyzing\nthe c(d; t) experimental dependence as well as the data on the hole\nlocalization in the pairs Cu-O obtained by XPS, the authors have made a\nconclusion about the nature of observed aging effects. The latter are likely to\nbe related to the transition of the Cu 3d9L-1 electron configuration to Cu 3d8\nfor copper in the basal plane of YBa2Cu3O6+d at RT."
    },
    {
        "anchor": "Spin Texture in Type-II Weyl Semimetal WTe2: We determine the band structure and spin texture of WTe2 by spin- and\nangle-resolved photoemission spectroscopy (SARPES). With the support of\nfirst-principles calculations, we reveal the existence of spin polarization of\nboth the Fermi arc surface states and bulk Fermi pockets. Our results support\nWTe2 to be a type-II Weyl semimetal candidate and provide important information\nto understand its extremely large and nonsaturating magnetoresistance.",
        "positive": "Stabilization Mechanism of ZnO nanoparticles by Fe doping: Surprisingly low solubility and toxicity of Fe-doped ZnO nanoparticles is\nelucidated on the basis of first-principles calculations. Various ZnO surfaces\nthat could be present in nanoparticles are subject to substitutional Fe doping.\nWe show that Fe stabilizes polar instable surfaces, while non-polar surfaces,\nnamely (1010) and (1120), remain intact. Polar surfaces can be stabilized\nindirectly through Fe2+-Fe3+ pair assisted charge transfer, what reduces\nsurface polarity and therefore, the solubility in polar solvents."
    },
    {
        "anchor": "From Brittle to Ductile Fracture in Disordered Materials: We introduce a lattice model able to describe damage and yielding in\nheterogeneous materials ranging from brittle to ductile ones. Ductile fracture\nsurfaces, obtained when the system breaks once the strain is completely\nlocalized, are shown to correspond to minimum energy surfaces. The similarity\nof the resulting fracture paths to the limits of brittle fracture or minimum\nenergy surfaces is quantified. The model exhibits a smooth transition from\nbrittleness to ductility. The dynamics of yielding exhibits avalanches with a\npower-law distribution.",
        "positive": "Hubbard-corrected DFT energy functionals: the LDA+U description of\n  correlated systems: The aim of this review article is to assess the descriptive capabilities of\nthe Hubbard-rooted LDA+U method and to clarify the conditions under which it\ncan be expected to be most predictive. The paper illustrates the theoretical\nfoundation of LDA+U and prototypical applications to the study of correlated\nmaterials, discusses the most relevant approximations used in its formulation,\nand makes a comparison with other approaches also developed for similar\npurposes. Open \"issues\" of the method are also discussed, including the\ncalculation of the electronic couplings (the Hubbard U), the precise expression\nof the corrective functional and the possibility to use LDA+U for other classes\nof materials. The second part of the article presents recent extensions to the\nmethod and illustrates the significant improvements they have obtained in the\ndescription of several classes of different systems. The conclusive section\nfinally discusses possible future developments of LDA+U to further enlarge its\npredictive power and its range of applicability."
    },
    {
        "anchor": "Quantitative nanoparticle structures from ultrafast electron\n  crystallography data: We describe the quantitative refinement of nanoparticle structures from gold\nnanoparticles probed by ultrafast electron crystallography (UEC). We establish\nthe equivalence between the modified radial distribution function employed in\nUEC and the atomic pair distribution function (PDF) used in x-ray and neutron\npowder diffraction analysis. By leveraging PDF refinement techniques, we\ndemonstrate that UEC data are of sufficient quality to differentiate between\ncuboctahedral, decahedral and icosahedral nanoparticle models. Furthermore, we\nidentify the signatures of systematic errors that may occur during data\nreduction and show that atomic positions refined from UEC are robust to these\nerrors. This work serves as a foundation for reliable quantitative structural\nanalysis of time-resolved laser-excited nanoparticle states.",
        "positive": "Probing the Electronic States in Black Phosphorus Vertical\n  Heterostructures: Atomically thin black phosphorus (BP) is a promising two-dimensional material\nfor fabricating electronic and optoelectronic nano-devices with high mobility\nand tunable bandgap structures. However, the charge-carrier mobility in\nfew-layer phosphorene (monolayer BP) is mainly limited by the presence of\nimpurity and disorders. In this study, we demonstrate that vertical BP\nheterostructure devices offer great advantages in probing the electron states\nof monolayer and few-layer phosphorene at temperatures down to 2 K through\ncapacitance spectroscopy. Electronic states in the conduction and valence bands\nof phosphorene are accessible over a wide range of temperature and frequency.\nExponential band tails have been determined to be related to disorders. Unusual\nphenomena such as the large temperature-dependence of the electron state\npopulation in few-layer phosphorene have been observed and systematically\nstudied. By combining the first-principles calculation, we identified that the\nthermal excitation of charge trap states and oxidation-induced defect states\nwere the main reasons for this large temperature dependence of the electron\nstate population and degradation of the on-off ratio in phosphorene\nfield-effect transistors."
    },
    {
        "anchor": "Molecular Modeling of the Microstructure Evolution during the\n  Carbonization of PAN-Based Carbon Fibers: Development of high strength carbon fibers (CFs) requires an understanding of\nthe relationship between the processing conditions, microstructure and\nresulting properties. We developed a molecular model that combines kinetic\nMonte Carlo (KMC) and molecular dynamics (MD) techniques to predict the\nmicrostructure evolution during the carbonization process of carbon fiber\nmanufacturing. The model accurately predicts the cross-sectional microstructure\nof carbon fibers, predicting features such as graphitic sheets and hairpin\nstructures that have been observed experimentally. We predict the transverse\nmodulus of the resulting fibers and find that the modulus is slightly lower\nthan experimental values, but is up to an order of magnitude lower than ideal\ngraphite. We attribute this to the perfect longitudinal texture of our\nsimulated structures, as well as the chain sliding mechanism that governs the\ndeformation of the fibers, rather than the van der Waals interaction that\ngoverns the modulus for graphite. We also observe that high reaction rates\nresult in porous structures that have lower moduli.",
        "positive": "Mechanical Metamaterials with Negative Compressibility Transitions: When tensioned, ordinary materials expand along the direction of the applied\nforce. Here, we explore network concepts to design metamaterials exhibiting\nnegative compressibility transitions, during which a material undergoes\ncontraction when tensioned (or expansion when pressured). Continuous\ncontraction of a material in the same direction of an applied tension, and in\nresponse to this tension, is inherently unstable. The conceptually similar\neffect we demonstrate can be achieved, however, through destabilisations of\n(meta)stable equilibria of the constituents. These destabilisations give rise\nto a stress-induced solid-solid phase transition associated with a twisted\nhysteresis curve for the stress-strain relationship. The strain-driven\ncounterpart of negative compressibility transitions is a force amplification\nphenomenon, where an increase in deformation induces a discontinuous increase\nin response force. We suggest that the proposed materials could be useful for\nthe design of actuators, force amplifiers, micro-mechanical controls, and\nprotective devices."
    },
    {
        "anchor": "Quadratic magnetoelectric effect during field cooling in sputter grown\n  Cr$_2$O$_3$ films: Cr$_2$O$_3$ is the archetypal magnetoelectric (ME) material, which has a\nlinear coupling between electric and magnetic polarizations. Quadratic ME\neffects are forbidden for the magnetic point group of Cr$_2$O$_3$, due to\nspace-time inversion symmetry. In Cr$_2$O$_3$ films grown by sputtering, we\nfind a signature of a quadratic ME effect that is not found in bulk single\ncrystals. We use Raman spectroscopy and magetization measurements to deduce the\nremoval of space-time symmetry, and corroborate the emergence of the quadratic\nME effect. We propose that meta-stable site-selective trace dopants remove the\nspace, time, and space-time inversion symmetries from the original magnetic\npoint group of bulk Cr$_2$O$_3$. We include the quadratic ME effect in a model\ndescribing the switching process during ME field cooling, and estimate the\neffective quadratic susceptibility value. The quadratic magnetoelectric effect\nin a uniaxial antiferromagnet is promising for multifunctional\nantiferromagnetic and magnetoelectric devices that can incorporate optical,\nstrain-induced, and multiferroic effects.",
        "positive": "Wurtzite (Ga,Mn)As nanowire shells with ferromagnetic properties: (Ga,Mn)As in wurtzite crystal structure, is coherently grown by molecular\nbeam epitaxy on the {1100} side facets of wurtizte (Ga,In)As nanowires and\nfurther encapsulated by (Ga,Al)As and low temperature GaAs. For the first time\na true long-range ferromagnetic magnetic order is observed in non-planar\n(Ga,Mn)As, which is attributed to a more effective hole confinement in the\nshell containing Mn by a proper selection/choice of both the core and outer\nshell materials."
    },
    {
        "anchor": "Influence of Zeeman splitting and thermally excited polaron states on\n  magneto-electrical and magneto-thermal properties of magnetoresistive\n  polycrystalline manganite La_{0.8}Sr_{0.2}MnO_3: Some possible connection between spin and charge degrees of freedom in\nmagneto-resistive manganites is investigated through a thorough experimental\nstudy of the magnetic (AC susceptibility and DC magnetization) and transport\n(resistivity and thermal conductivity) properties. Measurements are reported in\nthe case of well characterized polycrystalline La_{0.8}Sr_{0.2}MnO_3 samples.\nThe experimental results suggest rather strong field-induced polarization\neffects in our material, clearly indicating the presence of ordered FM regions\ninside the semiconducting phase. Using an analytical expression which fits the\nspontaneous DC magnetization, the temperature and magnetic field dependences of\nboth electrical resistivity and thermal conductivity data are found to be well\nreproduced through a universal scenario based on two mechanisms: (i) a\nmagnetization dependent spin polaron hopping influenced by a Zeeman splitting\neffect, and (ii) properly defined thermally excited polaron states which have\nto be taken into account in order to correctly describe the behavior of the\nless conducting region. Using the experimentally found values of the magnetic\nand electron localization temperatures, we obtain L=0.5nm and m_p=3.2m_e for\nestimates of the localization length (size of the spin polaron) and effective\npolaron mass, respectively.",
        "positive": "Towards High-Performance Two-Dimensional Black Phosphorus Optoelectronic\n  Devices: the Role of Metal Contacts: The metal contacts on 2D black phosphorus field-effect transistor and\nphotodetectors are studied. The metal work functions can significantly impact\nthe Schottky barrier at the metal-semiconductor contact in black phosphorus\ndevices. Higher metal work functions lead to larger output hole currents in\np-type transistors, while ambipolar characteristics can be observed with lower\nwork function metals. Photodetectors with record high photoresponsivity (223\nmA/W) are demonstrated on black phosphorus through contact-engineering."
    },
    {
        "anchor": "Locally enhanced conductivity due to the tetragonal domain structure in\n  LaAlO$_{3}$/SrTiO$_{3}$ heterointerfaces: The ability to control materials properties through interface engineering is\ndemonstrated by the appearance of conductivity at the interface of certain\ninsulators, most famously the {001} interface of the band insulators\nLaAlO$_{3}$ and TiO$_{2}$-terminated SrTiO$_{3}$ (STO). Transport and other\nmeasurements in this system show a plethora of diverse physical phenomena. To\nbetter understand the interface conductivity, we used scanning superconducting\nquantum interference device microscopy to image the magnetic field locally\ngenerated by current in an interface. At low temperature, we found that the\ncurrent flowed in conductive narrow paths oriented along the crystallographic\naxes, embedded in a less conductive background. The configuration of these\npaths changed on thermal cycling above the STO cubic-to-tetragonal structural\ntransition temperature, implying that the local conductivity is strongly\nmodified by the STO tetragonal domain structure. The interplay between\nsubstrate domains and the interface provides an additional mechanism for\nunderstanding and controlling the behaviour of heterostructures.",
        "positive": "Emergence of one-dimensional wires of free carriers in\n  transition-metal-dichalcogenide nanostructures: We highlight the emergence of metallic states in two-dimensional\ntransition-metal-dichalcogenide nanostructures -nanoribbons, islands, and\ninversion domain boundaries- as a widespread and universal phenomenon driven by\nthe polar discontinuities occurring at their edges or boundaries. We show that\nsuch metallic states form one-dimensional wires of electrons or holes, with a\nfree charge density that increases with the system size, up to complete\nscreening of the polarization charge, and can also be controlled by the\nspecific edge or boundary configurations, e.g. through chemisorption of\nhydrogen or sulfur atoms at the edges. For triangular islands, local polar\ndiscontinuities occur even in the absence of a total dipole moment for the\nisland and lead to an accumulation of free carriers close to the edges,\nproviding a consistent explanation of previous experimental observations. To\nfurther stress the universal character of these mechanisms, we show that polar\ndiscontinuities give rise to metallic states also at inversion domain\nboundaries. These findings underscore the potential of engineering\ntransition-metal-dichalcogenide nanostructures for manifold applications in\nnano- and opto-electronics, spintronics, catalysis, and solar-energy\nharvesting."
    },
    {
        "anchor": "Local structure study of the orbital order/disorder transition in\n  LaMnO$_3$: We use a combination of neutron and X-ray total scattering measurements\ntogether with pair distribution function (PDF) analysis to characterise the\nvariation in local structure across the orbital order--disorder transition in\nLaMnO$_3$. Our experimental data are inconsistent with a conventional\norder--disorder description of the transition, and reflect instead the\nexistence of a discontinuous change in local structure between ordered and\ndisordered states. Within the orbital-ordered regime, the neutron and X-ray\nPDFs are best described by a local structure model with the same local orbital\narrangements as those observed in the average (long-range) crystal structure.\nWe show that a variety of meaningfully-different local orbital arrangement\nmodels can give fits of comparable quality to the experimental PDFs collected\nwithin the disordered regime; nevertheless, our data show a subtle but\nconsistent preference for the anisotropic Potts model proposed in \\emph{Phys\nRev.\\ B} {\\bf 79}, 174106 (2009). The key implications of this model are\nelectronic and magnetic isotropy together with the loss of local inversion\nsymmetry at the Mn site. We conclude with a critical assessment of the\ninterpretation of PDF measurements when characterising local symmetry breaking\nin functional materials.",
        "positive": "Thermal properties of materials from ab-initio quasi-harmonic phonons: This paper gives a short overview of the calculation of thermal properties of\nmaterials from first principles, using the Quasi-Harmonic Approximation (QHA).\nWe first introduce some of the thermal properties of interest and describe how\nthey can be calculated in the framework of the QHA; then we briefly recall\nDensity-Functional Perturbation Theory as a tool for calculating phonons from\nfirst principles, and present some codes that implement it; finally we review\nrecent applications of first-principle QHA."
    },
    {
        "anchor": "Electronic structure of Diluted Magnetic Semiconductors\n  $Ga_{1-x}Mn_{x}N$ and $Ga_{1-x}Cr_{x}N$: We have undertaken a study of diluted magnetic semiconductors\n$Ga_{1-x}Mn_{x}N$ and $Ga_{1-x}Cr_{x}N$ with $x=0.0625, 0.125$, using the all\nelectron linearized augmented plane wave method (LAPW) for different\nconfigurations of Mn as well as Cr. We study four possible configurations of\nthe impurity in the wurtzite GaN structure to predict energetically most\nfavorable structure within the 32 atom supercell and conclude that the\nnear-neighbor configuration has the lowest energy. We have also analyzed the\nferro-magnetic as well as anti-ferromagnetic configurations of the impurity\natoms. The density of states as well as bandstructure indicate half metallic\nstate for all the systems. $T_c$ has also been estimated for the above systems.",
        "positive": "Investigations of temperature-dependent photoluminescence of uncoated\n  and silver-coated CdS quantum dots: We report temperature-dependent photoluminescence (PL) studies and PL\nrelaxation dynamics for uncoated and silver-coated CdS quantum dots (QDs).\nRoom-temperature photoluminescence studies indicate that the presence of silver\ncoating on CdS QD samples enhances the blue luminescence corresponding to the\nband-to-band transitions by a factor of ten compared to the uncoated samples.\nFurthermore, the decay time measurements using Time Correlated Single Photon\nCounting technique demonstrate F\\\"{o}rster resonance energy transfer (FRET)\nbetween silver-shell and CdS-core in silver-coated CdS QD samples. A detailed\ninvestigation of temperature-dependent PL spectra of uncoated CdS QD samples\nreveals the role of thermally-activated surface-trap states, exciton-LO phonon\ncoupling and ionized impurity scattering. In case of silver-coated QDs, the\ntemperature-dependent PL peak energy corresponding to the band-to-band\ntransitions presents a consecutive red-blue-red shift (S-shaped) behavior.\nWhereas, the full width at half maximum (FWHM) shows a successive blue-red-blue\nshift (inverted S-shaped) characteristic with increasing temperature."
    },
    {
        "anchor": "Controlling quantum spin Hall state via strain in various stacking\n  bilayer phosphorene: Quantum spin Hall (QSH) state of matter has a charge excitation bulk bandgap\nand a pair of gapless spin-filtered edge-states, which can support\nbackscattering-free transport. Bilayer phosphorene possesses a large tunable\nbandgap and high carrier mobilities, and therefore has the widely potential\napplications in nanoelectronics and optics. Here, we demonstrate an\nstrain-induced electronic topological phase transition from a normal to QSH\nstate in bilayer phosphorene accompanying by a band inversion that changes\n$\\mathbbm{Z}_{2}$ from 0 to 1, which is highly dependent on the interlayer\nstacking. When the bottom layer is shifted by 1/2 unit cell along axial\ndirection with respect to the top layer, the topological bandgap reaches up to\n92.5 meV, which is sufficiently large to realize the QSH effect at room\ntemperature. Its optical absorption spectrum becomes broadened, and even\nextends to the far-infra-red region leading to a wider range of brightness,\nwhich is highly desirable in optic devices.",
        "positive": "Dissipation of micro-cantilevers as a function of air pressure and\n  metallic coating: In this letter, we characterize the internal dissipation of coated\nmicro-cantilevers through their mechanical thermal noise. Using a home-made\ninterferometric setup, we achieve a resolution down to 1E-14m/rtHz in the\nmeasurement of their deflection. With the use of the fluctuation dissipation\ntheorem and of the Kramers-Kronig relations, we rebuilt the full mechanical\nresponse function from the measured noise spectrum, and investigate frequency\ndependent dissipation as a function of the air pressure and of the nature of\nthe metallic coatings. Using different thicknesses of gold coatings, we discuss\nthe source of the internal viscoelastic damping."
    },
    {
        "anchor": "Thickness Dependent Magnetic Transition in Few Layer 1T Phase CrTe2: Room temperature two-dimensional (2D) ferromagnetism is highly desired in\npractical spintronics applications. Recently, 1T phase CrTe2 (1T-CrTe2)\nnanosheets with five and thicker layers have been successfully synthesized,\nwhich all exhibit the properties of ferromagnetic (FM) metals with Curie\ntemperatures around 305 K. However, whether the ferromagnetism therein can be\nmaintained when continuously reducing the nanosheet's thickness to monolayer\nlimit remains unknown. Here, through first-principles calculations, we explore\nthe evolution of magnetic properties of 1 to 6 layers CrTe2 nanosheets and\nseveral interesting points are found: First, unexpectedly, monolayer CrTe2\nprefers a zigzag antiferromagnetic (AFM) state with its energy much lower than\nthat of FM state. Second, in 2 to 4 layers CrTe2, both the intralayer and\ninterlayer magnetic coupling are AFM. Last, when the number of layers is equal\nto or greater than five, the intralayer and interlayer magnetic coupling become\nFM. Theoretical analysis reveals that the in-plane lattice contraction of few\nlayer CrTe2 compared to bulk is the main factor producing intralayer AFM-FM\nmagnetic transition. At the same time, as long as the intralayer coupling gets\nFM, the interlayer coupling will concomitantly switch from AFM to FM. Such\nhighly thickness dependent magnetism provides a new perspective to control the\nmagnetic properties of 2D materials.",
        "positive": "An \\emph{ab initio} study on split silicon-vacancy defect in diamond:\n  electronic structure and related properties: The split silicon-vacancy defect (SiV) in diamond is an electrically and\noptically active color center. Recently, it has been shown that this color\ncenter is bright and can be detected at the single defect level. In addition,\nthe SiV defect shows a non-zero electronic spin ground state that potentially\nmakes this defect an alternative candidate for quantum optics and metrology\napplications beside the well-known nitrogen-vacancy color center in diamond.\nHowever, the electronic structure of the defect, the nature of optical\nexcitations and other related properties are not well-understood. Here we\npresent advanced \\emph{ab initio} study on SiV defect in diamond. We determine\nthe formation energies, charge transition levels and the nature of excitations\nof the defect. Our study unravel the origin of the dark or shelving state for\nthe negatively charged SiV defect associated with the 1.68-eV photoluminescence\ncenter."
    },
    {
        "anchor": "Chiral Quasiparticles at the Fermi Surface of the Weyl Semimetal TaAs: Tantalum arsenide is a member of the non-centrosymmetric monopnictides, which\nare putative Weyl semimetals. In these materials, three-dimensional chiral\nmassless quasiparticles, the so-called Weyl fermions, are predicted to induce\nnovel quantum mechanical phenomena, such as the chiral anomaly and topological\nsurface states. However, their chirality is only well-defined if the Fermi\nlevel is close enough to the Weyl points that separate Fermi surface pockets of\nopposite chirality exist. In this article, we present the bulk Fermi surface\ntopology of high quality single crystals of TaAs, as determined by\nangle-dependent Shubnikov-de Haas and de Haas-van Alphen measurements combined\nwith ab-initio band-structure calculations. Quantum oscillations originating\nfrom three different types of Fermi surface pocket were found in magnetization,\nmagnetic torque, and mag- netoresistance measurements performed in magnetic\nfields up to 14 T and temperatures down to 1.8 K. Of these Fermi pockets, two\nare pairs of topologically non-trivial electron pockets around the Weyl points\nand one is a trivial hole pocket. Unlike the other members of the\nnon-centrosymmetric monopnictides, TaAs is the first Weyl semimetal candidate\nwith the Fermi energy suffciently close to both types of Weyl points to\ngenerate chiral quasiparticles at the Fermi surface.",
        "positive": "Ge/Si(001) Heterostructures with Quantum Dots: Formation, Defects,\n  Photo-Electromotive Force and Terahertz Conductivity: Issues of Ge hut cluster nucleation and growth at low temperatures on the\nGe/Si(001) wetting layer are discussed on the basis of explorations performed\nby high resolution STM and in-situ RHEED. Data of HRTEM investigations of Ge/Si\nheterostructures are presented with the focus on low-temperature formation of\nperfect multilayer films. Exploration of the photovoltaic effect in Si\np--i--n-structures with Ge quantum dots allowed us to propose a new approach to\ndesigning of infrared detectors. First data on THz dynamical conductivity of\nGe/Si(001) heterostructures in the temperature interval from 5 to 300 K and\nmagnetic fields up to 6 T are reported."
    },
    {
        "anchor": "Theoretical insights into the hydrophobicity of low index CeO2 surfaces: The hydrophobicity of CeO2 surfaces is examined here. Since wettability\nmeasurements are extremely sensitive to experimental conditions, we propose a\ngeneral approach to obtain contact angles between water and ceria surfaces of\nspecified orientations based on density functional calculations. In particular,\nwe analysed the low index surfaces of this oxide to establish their\ninteractions with water. According to our calculations, the CeO2 (111) surface\nwas the most hydrophobic with a contact angle of {\\Theta} = 112.53{\\deg}\nfollowed by (100) with {\\Theta} = 93.91{\\deg}. The CeO2 (110) surface was, on\nthe other hand, mildly hydrophilic with {\\Theta} = 64.09{\\deg}. By combining\nour calculations with an atomistic thermodynamic approach, we found that the O\nterminated (100) surface was unstable unless fully covered by molecularly\nadsorbed water. We also identified a strong attractive interaction between the\nhydrogen atoms in water molecules and surface oxygen, which gives rise to the\nhydrophilic behaviour of (110) surfaces. Interestingly, the adsorption of water\nmolecules on the lower-energy (111) surface stabilises oxygen vacancies, which\nare expected to enhance the catalytic activity of this plane. The findings here\nshed light on the origin of the intrinsic wettability of rare earth oxides in\ngeneral and CeO2 surfaces in particular and also explain why CeO2 (100) surface\nproperties are so critically dependant on applied synthesis methods.",
        "positive": "Crucible aperture: an effective way to reduce source oxidation in oxide\n  molecular beam epitaxy process: Growing multi-elemental complex-oxide structures using an MBE (Molecular Beam\nEpitaxy) technique requires precise control of each source flux. However, when\nthe component elements have significantly different oxygen affinities,\nmaintaining stable fluxes for easily oxidizing elements is challenging because\nof a source oxidation problem. Here, using Sr as a test source, we show that a\ncrucible aperture insert scheme significantly reduces the source oxidation in\nan oxide-MBE environment. The crucible aperture insert was shaped like a disk\nwith a hole at the center and was mounted inside the crucible; it blocks most\nof the oxygen species coming to the source, thus reducing the source oxidation.\nHowever, the depth of the aperture disk was critical for its performance; an\nill-positioned aperture could make the flux stability even worse. With an\noptimally positioned aperture insert, the crucible exhibited more than four\ntimes improvement in Sr flux stability, compared to a conventional,\nnon-apertured crucible."
    },
    {
        "anchor": "Light-field-driven non-Ohmic current and Keldysh crossover in a Weyl\n  semimetal: In recent years, coherent electrons driven by light fields have attracted\nsignificant interest in exploring novel material phases and functionalities.\nHowever, observing coherent light-field-driven electron dynamics in solids is\nchallenging because the electrons are scattered within several ten femtoseconds\nin ordinary materials, and the coherence between light and electrons is\ndisturbed. However, when we use Weyl semimetals, the electron scattering\nbecomes relatively long (several hundred femtoseconds - several picoseconds),\nowing to the suppression of the back-scattering process. This study presents\nthe light-field-driven dynamics by the THz pulse to Weyl semimetal Co3Sn2S2,\nwhere the intense THz pulse of a monocycle electric field nonlinearly generates\ndirect current (DC) via coherent acceleration without scattering and\nnon-adiabatic excitation (Landau-Zener Transition). In other words, the\nnon-Ohmic current appears in the Weyl semimetal with a combination of the long\nrelaxation time and an intense THz pulse. This nonlinear DC generation also\ndemonstrates a Keldysh crossover from a photon picture to a light-field picture\nby increasing the electric field strength.",
        "positive": "Magnetic Electrides: High-Throughput Material Screening, Intriguing\n  Properties, and Applications: Electrides are a unique class of electron-rich materials where excess\nelectrons are localized in interstitial lattice sites as anions, leading to a\nrange of unique properties and applications. While hundreds of electrides have\nbeen discovered in recent years, magnetic electrides have received limited\nattention, with few investigations into their fundamental physics and practical\napplications. In this work, 51 magnetic electrides (12 antiferromagnetic, 13\nferromagnetic, and 26 interstitial-magnetic) were identified using\nhigh-throughput computational screening methods and the latest Material Project\ndatabase. Based on their compositions, these magnetic electrides can be\nclassified as magnetic semiconductors, metals, or half-metals, each with unique\ntopological states and excellent catalytic performance for N2 fixation due to\ntheir low work functions and excess electrons. The novel properties of magnetic\nelectrides suggest potential applications in spintronics, topological\nelectronics, electron emission, and as high-performance catalysts. This work\nmarks the beginning of a new era in the identification, investigation, and\npractical applications of magnetic electrides."
    },
    {
        "anchor": "Lifshitz transitions and elastic properties of Osmium under pressure: Topological changes of the Fermi surface under pressure may cause anomalies\nin the low-temperature elastic properties. Our density functional calculations\nfor elemental Osmium evidence that this metal undergoes three such Lifshitz\ntransitions in the pressure range between 70 GPa and 130 GPa. The related\nelastic anomalies are, however, invisibly weak. The critical pressures\nconsiderably exceed the values for recently measured and calculated anomalies\nin the pressure (P) dependence of the hexagonal c/a lattice parameter ratio\nclose to 25 GPa. We demonstrate that the latter anomalies are statistically not\nsignificant and that (c/a)(P) can be fitted equally well by a smooth\ndependence.",
        "positive": "Observation of Longitudinal Spin Seebeck Effect with Various Transition\n  Metal Films: We evaluated the thermoelectric properties of longitudinal spin Seebeck\ndevices by using ten different transition metals (TMs). Both the intensity and\nsign of spin Seebeck coefficients were noticeably dependent on the degree of\nthe inverse spin Hall effect and the resistivity of each TM film. Spin\ndependent behaviors were also observed under ferromagnetic resonance. These\nresults indicate that the output of the spin Seebeck devices originates in the\nspin current."
    },
    {
        "anchor": "Flow curve approximation using Avitzur's model for barreling compression\n  test: The combination of the Cylindrical Profile Model (CPM) and Avitzur's model is\ncommonly used to determine flow stress curves in material testing using\ncompression test. In this process, stress is corrected for friction using\nAvitzur's model and the average strain is calculated from CPM. This study\nproposes a method for estimating strain based on Avitzur's model. The presented\ncase studies demonstrate the impact of this strain correction on the flow\ncurves. The results show that increasing friction leads to higher strain values\nat the center of the sample due to barreling. The proposed method provides a\nmore accurate interpretation of compression test results.",
        "positive": "Discovery of ideal Weyl points with helicoid surface states: Weyl points, serving as monopoles in the momentum space and laying the\nfoundation of topological gapless phases, have recently been experimentally\ndemonstrated in various physical systems. However, none of the observed Weyl\ndegeneracies are ideal: they either offset in energy or coexist with trivial\ndispersions at other momenta. The lack of an ideal Weyl system sets a serious\nlimit to the further development of Weyl physics and potential applications.\nHere, by constructing a photonic metamaterial, we experimentally observe an\nideal Weyl system, whose nodal frequencies are pinned by symmetries to exactly\nthe same value. Benefitting from the ideal Weyl nodes, we are able to map out\nthe complete evolution of the helicoid surface states spinning around the\nprojections of each Weyl nodes. Our discovery provides an ideal photonic\nplatform for Weyl systems and novel topological devices."
    },
    {
        "anchor": "Electronic configuration of Mn ions in the $\u03c0$-d molecular ferromagnet\n  $\u03b2$-Mn phthalocyanine studied by soft x-ray magnetic circular dichroism: We have studied the electronic structure of the molecular ferromagnet\n$\\beta$-Mn phthalocyanine ($\\beta$-MnPc) in a polycrystalline form, which has\nbeen reported to show ferromagnetism at T$<$8.6 K, by x-ray absorption\nspectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD). From the\nexperimental results and subsequent cluster-model calculation, we find that the\nferromagnetic Mn ion in $\\beta$-MnPc is largely in the $^4$$E$$_g$ ground state\narising from the ($e$$_{g}$)$^3$($b$$_{2g}$)$^1$($a$$_{1g}$)$^1$\n[($d_{xz,yz}$)$^3$($d_{xy}$)$^1$($d_{z^{2}}$)$^1$] configuration of the\nMn$^{2+}$ state. Considering that the highest occupied molecular orbital (HOMO)\nof MnPc with the $^4$$E$$_g$ ground state originates from the $a$$_{1g}$\norbital of the Mn$^{2+}$ ion, it is proposed that $a$$_{1g}$-$a$$_{1g}$\nexchange coupling via the $\\pi$ orbitals of the phthalocyanine ring plays a\ncrucial role in the ferromagnetism of $\\beta$-MnPc.",
        "positive": "Thermally-activated precipitation strengthening: Precipitation strengthening is a key strengthening method for metallic\nmaterials. However, the temperature effect on precipitation strengthening is\nstill unclear to date. Based on dislocation theory, a thermally-activated\nprecipitation strengthening model is built by considering the competition\nbetween shear and bypass mechanisms. For medium-sized precipitate particles,\nthe thermally-activated shear mechanism dominates the precipitation\nstrengthening, resulting in a plateau region. While, for large or very fine\nprecipitate particles, the thermally-activated bypass mechanism dominates the\nprecipitation strengthening, leading to the strengthening or weakening regions.\nMoreover, the effects of precipitate phase volume fraction, temperature, shear\nmodulus, strain rate, and mobile dislocation density on precipitation\nstrengthening are also investigated. This study not only provides new insights\ninto precipitation strengthening from the perspective of thermal activation but\nalso offers clear guidance for the design of new materials."
    },
    {
        "anchor": "Giant Strain Response of Charge Modulation and Singularity in a Kagome\n  Superconductor: Tunable quantum materials hold great potential for applications. Of special\ninterest are materials in which small lattice strain induces giant electronic\nresponses. The kagome compounds AV3Sb5 (A = K, Rb, Cs) provide a testbed for\nsuch singular electronic states. In this study, through angle-resolved\nphotoemission spectroscopy, we provide comprehensive spectroscopic measurements\nof the giant responses induced by compressive and tensile strains on the\ncharge-density-wave (CDW) order parameter and high-order van Hove singularity\n(HO-VHS) in CsV3Sb5. We observe a tripling of the CDW gap magnitudes with ~1%\nstrain, accompanied by the changes of both energy and mass of the saddle-point\nfermions. Our results reveal an anticorrelation between the unconventional CDW\norder parameter and the mass of a HO-VHS, and highlight the role of the latter\nin the superconducting pairing. The giant electronic responses uncover a rich\nstrain tunability of the versatile kagome system in studying quantum interplays\nunder lattice perturbations.",
        "positive": "Eshelbian mechanics of novel materials: Quasicrystals: In this work, the so-called Eshelbian or configurational mechanics of\nquasicrystals is presented. Quasicrystals are considered as a prototype of\nnovel materials. Material balance laws for quasicrystalline materials with\ndislocations are derived in the framework of generalized incompatible\nelasticity theory of quasicrystals. Translations, scaling transformations as\nwell as rotations are examined; the latter presents particular interest due to\nthe quasicrystalline structure. This derivation provides important quantities\nof the Eshelbian mechanics, as the Eshelby stress tensor, the scaling flux\nvector, the angular momentum tensor, the configurational forces (Peach-Koehler\nforce, Cherepanov force, inhomogeneity force or Eshelby force), the\nconfigurational work and the configurational vector moments for dislocations in\nquasicrystals. The corresponding $J$-, $M$-, and $L$-integrals for dislocation\nloops and straight dislocations in quasicrystals are derived and discussed.\nMoreover, the explicit formulas of the $J$-, $M$-, and $L$-integrals for\nparallel screw dislocations in one-dimensional hexagonal quasicrystals are\nobtained. Through this derivation, the physical interpretation of the $J$-,\n$M$-, and $L$-integrals for dislocations in quasicrystals is revealed and their\nconnection to the Peach-Koehler force, the interaction energy and the\nrotational vector moment (torque) of dislocations in quasicrystals is\nestablished."
    },
    {
        "anchor": "Spectromicroscopic measurement of surface and bulk band structure\n  interplay in a disordered topological insulator: Topological insulators are bulk semiconductors that manifest in-gap massless\nDirac surface states due to the topological bulk-boundary correspondence\nprinciple [1-3]. These surface states have been a subject of tremendous ongoing\ninterest, due both to their intrinsic properties and to higher order emergence\nphenomena that can be achieved by manipulating the interface environment\n[4-11]. Here, angle resolved photoemission (ARPES) spectromicroscopy and\nsupplementary scanning tunneling microscopy (STM) are performed on the model\ntopological insulator Bi2Se3 to investigate the interplay of crystallographic\ninhomogeneity with the topologically ordered bulk and surface band structure.\nQuantitative analysis methods are developed to obtain key spectroscopic\ninformation in spite of a limited dwell time on each measured point. Band\nenergies are found to vary on the scale of 50 meV across the sample surface,\nenabling single-sample measurements that are analogous to a multi-sample doping\nseries (termed a \"binning series\"). Focusing separately on the surface and bulk\nelectrons reveals a nontrivial hybridization-like interplay between\nfluctuations in the surface and bulk state energetics.",
        "positive": "Effects of the surface termination and oxygen vacancy positions and on\n  LaNiO$_{3}$ ultra-thin films: First-principles study: While ultra-thin layers of the LaNiO$_3$ film exhibit a remarkable\nmetal-insulator transition as the film thickness becomes smaller than a few\nunit cell (u.c.), the formation of oxygen vacancies and their effects on the\ncorrelated electronic structure have been rarely studied. Here, we investigate\nthe effects of the surface termination and the oxygen vacancy position on the\nelectronic properties and vacancy energetics of LaNiO$_3$ ultra-thin films\nusing density functional theory plus U (DFT+U). We find that oxygen vacancies\ncan be easily formed in the Ni layers with the NiO$_2$ terminated surface (0.5\nu.c. and 1.5 u.c. thickness) compared to the structures with the LaO terminated\nsurface and the in-plane vacancy is energetically favored than the out-of-plane\nvacancy. When two vacancy sites are allowed, the Ni square plane geometry is\nenergetically more stable in most cases as two oxygen vacancies tend to stay\nnear a Ni ion. The in-plane vacancy of the NiO$_2$ terminated structure is\nfavored since the released charge due to the oxygen vacancy can be easily\naccommodated in the $d_{x^2-y^2}$ orbital, which is less occupied than the\n$d_{z^2}$ orbital. Remarkably, the oxygen vacancy structure containing the Ni\nsquare-plane geometry becomes an insulating state in DFT+U with a sizable band\ngap of 1.2eV because the large crystal field splitting between $d_{z^2}$ and\n$d_{x^2-y^2}$ orbitals in the square-plane favors an insulating state and the\nMott insulating state is induced in other Ni sites due to strong electronic\ncorrelations."
    },
    {
        "anchor": "Dislocation dynamics formulation for self-climb of dislocation loops by\n  vacancy pipe diffusion: It has been shown in experiments that self-climb of prismatic dislocation\nloops by pipe diffusion plays important roles in their dynamical behaviors,\ne.g., coarsening of prismatic loops upon annealing, as well as the physical and\nmechanical properties of materials with irradiation. In this paper, we show\nthat this dislocation dynamics self-climb formulation that we derived in Ref.\n[1] is able to quantitatively describe the properties of self-climb of\nprismatic loops that were observed in experiments and atomistic simulations.\nThis dislocation dynamics formulation applies to self-climb by pipe diffusion\nfor any configurations of dislocations. For small circular prismatic loops, our\nformulation recovers the available models in the literature based on linearly\nmobility relation driven by the interaction force between the loops and an\nexternal stress gradient. We also present DDD implementation method of this\nself-climb formulation. Simulations performed show evolution, translation and\ncoalescence of prismatic loops as well as prismatic loops driven by an edge\ndislocation by self-climb motion and the elastic interaction between them.\nThese results are in excellent agreement with available experimental and\natomistic results. We have also performed systematic analyses of the behaviors\nof a prismatic loop under the elastic interaction with an infinite, straight\nedge dislocation by motions of self-climb and glide.",
        "positive": "Quantum conductance of MoS_2 armchair nanoribbons: Molybdenum disulfide (MoS2) is layered transition-metal dichalcogenide\n(TMDC), which in its monolayer form, has the direct bandgap of 1.8 eV. We\ninvestigated the effect of width and strain on quantum transport for MoS2\narmchair nanoribbons. That indicates MoS2 armchair nanoribbons are a good\ncandidate for transistors even with strain."
    },
    {
        "anchor": "High current, high efficiency graded band gap perovskite solar cells: Organic-inorganic halide perovskite materials have emerged as attractive\nalternatives to conventional solar cell building blocks. Their high light\nabsorption coefficients and long diffusion lengths suggest high power\nconversion efficiencies (PCE),1-5 and indeed perovskite-based single band gap\nand tandem solar cell designs have yielded impressive performances.1-16 One\napproach to further enhance solar spectrum utilization is the graded band gap,\nbut this has not been previously achieved for perovskites. In this study, we\ndemonstrate graded band gap perovskite solar cells with steady-state conversion\nefficiencies averaging 18.4%, with a best of 21.7%, all without reflective\ncoatings. An analysis of the experimental data yields high fill factors of ~75%\nand high short circuit current densities up to 42.1 mA/cm2. These cells, which\nare based on a novel architecture of two perovskite layers (MASnI3 and\nMAPbI3-xBrx), incorporating GaN, monolayer hexagonal boron nitride, and\ngraphene aerogel, display the highest efficiency ever reported for perovskite\nsolar cells.",
        "positive": "Topological Hall effect at above room temperature in heterostructures\n  composed of a magnetic insulator and a heavy metal: Non-volatile memory and computing technology rely on efficient read and write\nof ultra-tiny information carriers that do not wear out. Magnetic skyrmions are\nemerging as a potential carrier since they are topologically robust nanoscale\nspin textures that can be manipulated with ultralow current density. To date,\nmost of skyrmions are reported in metallic films, which suffer from additional\nOhmic loss and thus high energy dissipation. Therefore, skyrmions in magnetic\ninsulators are of technological importance for low-power information processing\napplications due to their low damping and the absence of Ohmic loss. Moreover,\nthey attract fundamental interest in studying various magnon-skyrmion\ninteractions11. Skyrmions have been observed in one insulating material\nCu2OSeO3 at cryogenic temperatures, where they are stabilized by bulk\nDzyaloshinskii-Moriya interaction. Here, we report the observation of magnetic\nskyrmions that survive above room temperature in magnetic insulator/heavy metal\nheterostructures, i.e., thulium iron garnet/platinum. The presence of these\nskyrmions results from the Dzyaloshinskii-Moriya interaction at the interface\nand is identified by the emergent topological Hall effect. Through tuning the\nmagnetic anisotropy via varying temperature, we observe skyrmions in a large\nwindow of external magnetic field and enhanced stability of skyrmions in the\neasy-plane anisotropy regime. Our results will help create a new platform for\ninsulating skyrmion-based room temperature low dissipation spintronic\napplications."
    },
    {
        "anchor": "In-plane force fields and elastic properties of graphene: Bond stretching and angle bending force fields, appropriate to describe\nin-plane motion of graphene sheets, are derived using first principles'\nmethods. The obtained force fields are fitted by analytical anharmonic energy\npotential functions, providing efficient means of calculations in molecular\nmechanics simulations. Numerical results regarding the mechanical behavior of\ngraphene monolayers under various loads, like uniaxial tension, hydrostatic\ntension, and shear stress, are presented, using both molecular dynamics\nsimulations and first principles' methods. Stress-strain curves and elastic\nconstants, such as, Young modulus, Poisson ratio, bulk modulus, and shear\nmodulus, are calculated. Our results are compared with corresponding\ntheoretical calculations as well as with available experimental estimates.\nFinally, the effect of the anharmonicity of the extracted potentials on the\nmechanical properties of graphene are discussed.",
        "positive": "Terahertz spin dynamics driven by a field-derivative torque: Efficient manipulation of magnetization at ultrashort time scales is of\nparticular interest for future technology. Here, we numerically investigate the\ninfluence of the so-called field-derivative torque, which was derived earlier\nbased on relativistic Dirac theory [Mondal et al., Phys. Rev. B 94, 144419\n(2016)], on the spin dynamics triggered by ultrashort laser pulses. We find\nthat only considering the THz Zeeman field can underestimate the spin\nexcitation in antiferromagnetic oxide systems as, e.g., NiO and CoO. However,\naccounting for both, the THz Zeeman torque and the field-derivative torque, the\namplitude of the spin excitation increases significantly. Studying the damping\ndependence of field-derivative torque we observe larger effects for materials\nhaving larger damping constants."
    },
    {
        "anchor": "Impact of thermal annealing on the interaction between monolayer MoS2\n  and Au: We have investigated the impact of thermal annealing on the interaction of\nsingle layer MoS2 and Au using Raman Spectroscopy. We found MoS2 has two main\nmodes of interactions with the underlying Au being either weakly-coupled or\nstrongly-coupled. The regions strongly-coupled to Au are hybridized to Au,\nminimally strained, and electron-doped. The weakly-coupled regions are found to\nbe slightly hole-doped with tensile strain of 1.0 %. The observed nanoscale\ninhomogeneities in doping would result in Au contacts having a large\nvariability in performance. The overall areal coverage of the strongly-coupled\nregions is not increased by thermal annealing, and the variability in the\ndegree of hybridization increases at annealing temperatures above 100 {\\deg}C.\nOur data also show that monolayer MoS2 starts to decouple from Au around 100\n{\\deg}C, becoming fully decoupled above 250 {\\deg}C, suggesting that monolayer\nMoS2 produced by Au-assisted mechanical exfoliation may be more easily\ntransferred off Au at elevated temperatures.",
        "positive": "Increased surface flashover voltage in microfabricated devices: With the demand for improved performance in microfabricated devices, the\nnecessity to apply greater electric fields and voltages becomes evident. When\noperating in vacuum, the voltage is typically limited by surface flashover\nforming along the surface of a dielectric. By modifying the fabrication process\nwe have discovered it is possible to more than double the flashover voltage.\nOur finding has significant impact on the realization of next-generation micro-\nand nano-fabricated devices and for the fabrication of on-chip ion trap arrays\nfor the realization of scalable ion quantum technology."
    },
    {
        "anchor": "Accelerated Aging in 3 mol%-Yttria-Stabilized Tetragonal Zirconia\n  Ceramics Sintered in Reducing Conditions: The aging behavior of 3-mol%-yttria-stabilized tetragonal zirconia (3Y-TZP)\nceramics sintered in air and in reducing conditions was investigated at\n140{\\deg}C in water vapor. It was observed by X-ray diffraction (XRD) that\n3Y-TZP samples sintered in reducing conditions exhibited significantly higher\ntetragonal-to-monoclinic transformation than samples with similar density and\naverage grain size values but obtained by sintering in air. This fact is\nexplained by the increase of the oxygen vacancy concentration and by the\npresence at the grain boundary region of a new aggregate phase formed because\nof the exolution of Fe2+ ions observed by X-ray photoelectron spectroscopy.",
        "positive": "First-Principles Study on NaxTiO2 with Trigonal Bipyramid Structures: An\n  Insight into Sodium-Ion Battery Anode Application: Developing efficient anode materials with low electrode voltage, high\nspecific capacity and superior rate capability is urgently required on the road\nto commercially viable sodium-ion batteries (SIBs). Aiming at finding a new SIB\nanode material, we investigate the electrochemical properties of NaxTiO2\ncompounds with unprecedented penta-oxygen-coordinated trigonal bipyramid (TB)\nstructures by using the first-principles calculations. Identifying the four\ndifferent TB phases, we perform the optimization of their crystal structures\nand calculate their energetics such as sodium binding energy, formation energy,\nelectrode potential and activation energy for Na ion migration. The\ncomputations reveal that TB-I phase can be the best choice among the four TB\nphases for the SIB anode material due to relatively low volume change under 4%\nupon Na insertion, low electrode voltage under 1.0 V with a possibility of\nrealizing the highest specific capacity of ~335 mAh/g from fully sodiation at x\n= 1, and reasonably low activation barriers under 0.35 eV at the Na content\nfrom x = 0.125 to x = 0.5. Through the analysis of electronic density of states\nand charge density difference upon sodiation, we find that the NaxTiO2\ncompounds in TB phases change from electron insulating to electron conducting\nmaterial due to the electron transfer from Na atom to Ti ion, ordering the Ti\n4+/Ti 3+ redox couple for SIB operation."
    },
    {
        "anchor": "Many-Body Simulation of Two-Dimensional Electronic Spectroscopy of\n  Excitons and Trions in Monolayer Transition-Metal Dichalcogenides: We present a many-body formalism for the simulation of time-resolved\nnonlinear spectroscopy and apply it to study the coherent interaction between\nexcitons and trions in doped transition-metal dichalcogenides. Although the\nformalism can be straightforwardly applied in a first-principles manner, for\nsimplicity we use a parameterized band structure and a static model dielectric\nfunction, both of which can be obtained from a calculation using the $GW$\napproximation. Our simulation results shed light on the interplay between\nsinglet and triplet trions in molybdenum- and tungsten-based compounds. Our\ntwo-dimensional electronic spectra are in excellent agreement with recent\nexperiments and we accurately reproduce the beating of a cross-peak signal\nindicative of quantum coherence between excitons and trions. Although we\nconfirm that the quantum beats in molybdenum-based monolayers unambigously\nreflect the exciton-trion coherence time, they are shown here to provide a\nlower-bound to the coherence time of tungsten analogues due to a destructive\ninterference emerging from coexisting singlet and triplet trions.",
        "positive": "Extending the scope and understanding of all-optical magnetization\n  switching in Gd-based alloys by controlling the underlying temperature\n  transients: We use the thickness of Cu layers to control all-optical switching of\nmagnetization in adjacent Gd$_{24}$(Fe$_9$0Co$_{10}$)$_{76}$ films. While\nincreasing the Cu thickness from 5 to 900nm has no effect on the switching\nthreshold, it significantly enlarges the fluence and pulse duration at which\nmultiple domains emerge. Having shown that thermally activated multi-domain\nformation limits the maximum fluence and pulse duration for controlled\nswitching, we demonstrate that continuous magnetization reversal precedes\nmulti-domain formation in Gd$_{18}$Dy$_4$Co$_{78}$ films excited with fluences\nslightly larger than the multi-domain threshold."
    },
    {
        "anchor": "Theoretical monitoring of energy transport on solid surfaces at\n  nano-metric scales: The surface is known to intercept energy from bombarding particles. This\nenergy then spreads over the surface. Before now, it has always been said that\nthe distribution of this energy landing on the surface is always Gaussian.\nHowever, in this paper, we clearly show, using a set of mathematical tools, the\nenergy distribution patterns on common, simple or ideal, solid surfaces. We\nconsider flat graphene, cubic and rhombohedra surfaces and indicate the energy\nleads which transport energy units from one atom to the other, away from the\nlanding site of the bombarding particle. The overall nano-scale pattern of the\nentire energy spread on the surfaces suggests a clearly non-Gaussian form at\nnano scales. This means the energy distribution on these surfaces can not be\nassumed to be uniformly distributed over the surface, at nano scales. The\nenergy travels faster along the length than along the breadth, thus the energy\ndistribution is anisotropic even on ideal lattice, at nano scales. The\ndifferent patterns, obtained, clearly show that the energy distribution into a\nmaterial, via its surface, is peculiar to the surface",
        "positive": "Resonant scattering of spin waves from a region of inhomogeneous\n  magnetic field in a ferromagnetic film: The transmission of a dipole-dominated spin wave in a ferromagnetic film\nthrough a localised inhomogeneity in the form of a magnetic field produced by a\ndc current through a wire placed on the film surface was studied experimentally\nand theoretically. It was shown that the amplitude and phase of the transmitted\nwave can be simultaneously affected by the current induced field, a feature\nthat will be relevant for logic based on spin wave transport.\n  The direction of the current creates either a barrier or well for spin wave\ntransmission. The main observation is that the current dependence of the\namplitude of the spin wave transmitted through the well inhomogeneity is\nnon-monotonic. The dependence has a minimum and an additional maximum. A theory\nwas constructed to clarify the nature of the maximum. It shows that the\ntransmission of spin waves through the inhomogeneity can be considered as a\nscattering process and that the additional maximum is a scattering resonance."
    },
    {
        "anchor": "\\textit{Ab initio} study on spin fluctuations of itinerant kagome magnet\n  FeSn: Kagome antiferromagnetic metal FeSn has become an attracting platform for the\nexploration of novel electronic states, such as topological Dirac states and\nthe formation of flat bands by localized electrons. Apart from the electronic\nproperties, Dirac magnons and flat magnon bands have also been proposed by\napplying simplified Heisenberg models to kagome magnetic systems.Inelastic\nneutron scattering studies on FeSn found well defined magnon dispersions at low\nenergies,but magnons at high energies are strongly dampled, which can not be\nexplained by localized spin models. In this paper, we utilize both linear spin\nwave theory and time-dependent density functional perturbation theory to\ninvestigate spin fluctuations of FeSn. Through the comparison of calculated\nspin wave spectra and Stoner continuum, we explicitly show that the damping of\nmagnons at high energies are due to the Landau damping, and the appearance of\nhigh energy optical-magnon like branches at the M and K point are resulted by\nrelatively low Stoner excitation intensity at those regions.",
        "positive": "A new investigation of oxygen flow influence on ITO thin films by\n  magnetron sputtering: ITO thin films were deposited on glass substrates by d.c. magnetron\nsputtering with varied oxygen flow rates. It was found that the optical\nabsorption decreases and optical absorption edge has blue shifts with the\nincreasing oxygen flow rate. Oxygen vacancy concentration was characterized and\nanalyzed by XPS. It is shown that the oxygen vacancy concentration increases\nwith oxygen flow rates, which is a different observation from the current\nunderstanding. The energy band structures associated with different vacancy\nconcentrations of ITO were calculated using the first-principle based on\ndensity functional theory. The calculation results show that the increase of\noxygen vacancies induces the increase of bands below Fermi level as well as the\npresence of a second band gap, which accounts for effects of the oxygen\nvacancies on the blue shifts."
    },
    {
        "anchor": "Electronic structure in a rare-earth based nodal-line semimetal\n  candidate PrSbTe: Nodal line semimetals feature topologically protected band crossings between\nthe bulk valence and conduction bands that extend along a finite dimension in\nthe form of a line or a loop. While ZrSiS and similar materials have attracted\nextensive research as hosts for the nodal line semimetallic phase, an\nalternative avenue has emerged in the form of isostructural rare-earth (RE)\nbased RESbTe materials. Such systems possess intriguing potentialities for\nharboring elements of magnetic ordering and electronic correlations owing to\nthe presence of 4f electrons intrinsic to the RE elements. In this study, we\nhave carried out angle resolved photoemission spectroscopy (ARPES) and\nthermodynamic measurements in conjunction with first principles computations on\nPrSbTe to elucidate its electronic structure and topological characteristics.\nMagnetic and thermal characterizations indicate the presence of well-localized\n4f states with the absence of any discernible phase transition down to 2 K. The\nARPES results reveal the presence of gapless Dirac crossings that correspond to\na nodal-line along the XR direction in the three-dimensional Brillouin zone.\nFurthermore, Dirac crossing that makes up nodal line, which forms a\ndiamond-shaped nodal plane centered at the center of the Brillouin zone is also\nidentified within the experimental resolution. This study on the electronic\nstructure of PrSbTe contributes to the understanding of the pivotal role played\nby spin-orbit coupling in the context of the RESbTe family of materials",
        "positive": "Contribution of X-ray experiments and modeling to the understanding of\n  the heterogeneous lithiation of graphite electrodes: Distributions of potential and lithium content inside lithium ion batteries\nhighly affects their performance and durability. An increased heterogeneity of\nthe lithium distribution is expected in thick electrodes with high energy\ndensities or cycling at high currents. To optimize electrodes and cells\ndesigns, it is crucial to probe lithium concentration gradients across the\ndepth of the electrode, but also to predict their occurrence and magnitude as a\nfunction of materials properties. Here, we follow the lithium distribution\nacross a $80~\\mu m$ thick porous graphite electrode using a $1~\\mu m$ focused\nsynchrotron X-ray beam. The sequential formation of the individual Li$_x$C$_6$\nphases during lithium de-insertion is extracted from X-ray diffraction\npatterns, allowing the quantification of lithium concentration across the\nelectrode thickness. Analyzing the evolution of heterogeneities as a function\nof time, we recover the striking features we predicted with a porous electrode\nmodel, including the succession of homogeneous and heterogeneous distributions\nof lithium. However, a clear difference is obtained at high stoichiometry, with\na much more homogeneous distribution than initially predicted. Revisiting the\ninterplay between transport and kinetic transfers limitations in the porous\nelectrode model, we suggest that the kinetics of lithium (de)-insertion is\nhighly reduced during the LiC$_6$/LiC$_{12}$ phase transition."
    },
    {
        "anchor": "Two-dimensional rare-earth Janus 2$\\textit{H}$-Gd$\\textit{XY}$\n  ($\\textit{X}$,$\\textit{Y}$=Cl, Br, I, $\\textit{X}$$\\neq$$\\textit{Y}$)\n  monolayers: Bipolar ferro-magnetic semiconductors with high Curie temperature\n  and large valley polarization: Two-dimensional (2D) ferromagnetic semiconductors show great interest due to\ntheir potential applications for the nanoscale electronic devices. In this\nwork, the Janus 2$H$-Gd$XY$ ($X$, $Y$=Cl, Br, I, $X$$\\neq$$Y$) monolayers with\nrare-earth element Gd (4$f^{7}$+5$d^{1}$) are predicted by the first-principles\ncalculations. Small exfoliation energy of less than 0.25 J/m$^{2}$ and\nexcellent dynamical/thermal stabilities can be confirmed for the Janus\n2$H$-Gd$XY$ monolayers, which exhibit the bipolar magnetic semiconductor\ncharacter with high Curie temperatures above 260 K and large spin-orbit\ncoupling effect, and can be further transformed into the half-semiconductor\nphase under proper tensile strains (5-6\\%). In addition, the in-plane magnetic\nanisotropy can be observed in the 2$H$-GdICl and 2$H$-GdIBr monolayers. On the\ncontrary, the 2$H$-GdBrCl monolayer exhibits perpendicular magnetic anisotropy\ncharacter, which originates from the competition between Gd-$p$/$d$ and halogen\natom-$p$ orbitals. Calculated valley optical actions of the Janus 2$H$-Gd$XY$\nmonolayers exhibit distinguished valley-selective circular dichroisms, which is\nexpected to realize the special valley excitation by polarized light.\nSpontaneously valley-Zeeman effect in the valance band for the Janus\n2$H$-Gd$XY$ monolayers induces a giant valley splitting of 60-120 meV, which is\nalso robust against various external biaxial strains. Tunable valley degree of\nfreedom in the Janus 2$H$-Gd$XY$ systems is very necessary for encoding and\nprocessing information.",
        "positive": "Changes in adsorption heights upon self-assembly of bicomponent\n  supramolecular networks: Codeposition of two molecular species [CuPc (donor) and PFP (acceptor)] on\nnoble metal (111) surfaces leads to the self-assembly of an ordered mixed layer\nwith maximized donor-acceptor contact area. The main driving force behind this\narrangement is assumed to be the intermolecular C-F...H-C hydrogen-bond\ninteractions. Such interactions would be maximized for a coplanar molecular\narrangement. However, precise measurement of molecule-substrate distances in\nthe molecular mixture reveals significantly larger adsorption heights for PFP\nthan for CuPc. Most surprisingly, instead of leveling to increase hydrogen bond\ninteractions, the height difference is enhanced in mixed layers as compared to\nthe heights found in single component CuPc and PFP layers, resulting in an\noverall reduced interaction with the underlying substrate. The influence of the\nincreased height of PFP on the interface dipole is investigated through work\nfunction measurements."
    },
    {
        "anchor": "Lattice Distortions Around a Tl+ Impurity in NaI:Tl+ and CsI:Tl+\n  Scintillators. An Ab Initio Study Involving Large Active Clusters: Ab initio Perturbed Ion cluster-in-the-lattice calculations of the impurity\ncenters NaI:Tl+ and CsI:Tl+ are pressented. We study several active clusters of\nincreasing complexity and show that the lattice relaxation around the Tl+\nimpurity implies the concerted movement of several shells of neighbors. The\nresults also reveal the importance of considering a set of ions that can\nrespond to the geometrical displacements of the inner shells by adapting\nselfconsistently their wave functions. Comparison with other calculations\ninvolving comparatively small active clusters serves to assert the significance\nof our conclusions. Contact with experiment is made by calculating absorption\nenergies. These are in excellent agreement with the experimental data for the\nmost realistic active clusters considered.",
        "positive": "Graphene/MoS2 van der Waals Bilayer as the Anode Material for Next\n  Generation Li-ion Battery: A First-Principles Investigation: We performed density functional theory (DFT) calculations for a bi-layered\nheterostructure combining a graphene layer with a MoS2 layer with and without\nintercalated Li atoms. Our calculations demonstrate the importance of the van\nder Waals (vdW) interaction, which is crucial for forming stable bonding\nbetween the layers. Our DFT calculation correctly reproduces the linear\ndispersion, or Dirac cone, feature at the Fermi energy for the isolated\ngraphene monolayer and the band gap for the MoS2 monolayer. For the combined\ngraphene/MoS2 bi-layer, we observe interesting electronic structure and density\nof states (DOS) characteristics near the Fermi energy, showing both the gap\nlike features of the MoS2 layer and in-gap states with linear dispersion\ncontributed mostly by the graphene layer. Our calculated total density of\nstates (DOS) in this vdW heterostructure reveals that the graphene layer\nsignificantly contributes to pinning the Fermi energy at the center of the band\ngap of MoS2. We also find that intercalating Li ions in between the layers of\nthe graphene/MoS2 heterostructure enhances the binding energy through orbital\nhybridizations between cations (Li adatoms) and anions (graphene and MoS2\nmonolayers). Moreover, we calculate the dielectric function of the Li\nintercalated graphene/MoS2 heterostructure, the imaginary component of which\ncan be directly compared with experimental measurements of optical conductivity\nin order to validate our theoretical prediction. We observe sharp features in\nthe imaginary component of the dielectric function, which shows the presence of\na Drude peak in the optical conductivity, and therefore metallicity in the\nlithiated graphene/MoS2 heterostructure."
    },
    {
        "anchor": "Substrate-induced structures of bismuth adsorption on graphene: a first\n  principle study: The geometric and electronic properties of Bi-adsorbed monolayer graphene,\nenriched by the strong effect of substrate, are investigated by\nfirst-principles calculations. The six-layered substrate, corrugated buffer\nlayer, and slightly deformed monolayer graphene are all simulated. Adatom\narrangements are thoroughly studied by analyzing the ground-state energies,\nbismuth adsorption energies, and Bi-Bi interaction energies of different adatom\nheights, inter-adatom distance, adsorption sites, and hexagonal positions. A\nhexagonal array of Bi atoms is dominated by the interactions between the buffer\nlayer and the monolayer graphene. An increase in temperature can overcome a\n$\\sim 50$ meV energy barrier and induce triangular and rectangular\nnanoclusters. The most stable and metastable structures agree with the scanning\ntunneling microscopy measurements. The density of states exhibits a finite\nvalue at the Fermi level, a dip at $\\sim -0.2$ eV, and a peak at $\\sim -0.6$\neV, as observed in the experimental measurements of the tunneling conductance.",
        "positive": "Common acoustic phonon lifetimes in inorganic and hybrid lead halide\n  perovskites: The acoustic phonons in the organic-inorganic lead halide perovskites have\nbeen reported to have anomalously short lifetimes over a large part of the\nBrillouin zone. The resulting shortened mean free paths of the phonons have\nbeen implicated as the origin of the low thermal conductivity. We apply neutron\nspectroscopy to show that the same acoustic phonon energy linewidth broadening\n(corresponding to shortened lifetimes) occurs in the fully inorganic\nCsPbBr$_{3}$ by comparing the results on the organic-inorganic\nCH$_{3}$NH$_{3}$PbCl$_{3}$. We investigate the critical dynamics near the three\nzone boundaries of the cubic $Pm\\overline{3}m$ Brillouin zone of CsPbBr$_{3}$\nand find energy and momentum broadened dynamics at momentum points where the\nCs-site ($A$-site) motions contribute to the cross section. Neutron diffraction\nis used to confirm that both the Cs and Br sites have unusually large thermal\ndisplacements with an anisotropy that mirrors the low temperature structural\ndistortions. The presence of an organic molecule is not necessary to disrupt\nthe low-energy acoustic phonons at momentum transfers located away from the\nzone center in the lead halide perovskites and such damping may be driven by\nthe large displacements or possibly disorder on the $A$ site."
    },
    {
        "anchor": "Vibrational properties of metastable polymorph structures by machine\n  learning: Despite vibrational properties being critical for the ab initio prediction of\nthe finite temperature stability and transport properties of solids, their\ninclusion in ab initio materials repositories has been hindered by expensive\ncomputational requirements. Here we tackle the challenge, by showing that a\ngood estimation of force constants and vibrational properties can be quickly\nachieved from the knowledge of atomic equilibrium positions using machine\nlearning. A random-forest algorithm trained on only 121 metastable structures\nof KZnF$_3$ reaches a maximum absolute error of 0.17 eV/$\\textrm\\AA^2$ for the\ninteratomic force constants, and it is much less expensive than training the\ncomplete force field for such compound. The predicted force constants are then\nused to estimate phonon spectral features, heat capacities, vibrational\nentropies, and vibrational free energies, which compare well with the ab initio\nones. The approach can be used for the rapid estimation of stability at finite\ntemperatures.",
        "positive": "Structure and Born effective charge determination for planar-zigzag\n  <beta>-poly(vinylidene fluoride) using density-functional theory: Two structures have been proposed in the literature for the b-phase of the\nferroelectric polymer, poly(vinylidene fluoride) (b-PVDF); planar-zigzag and\nalternatively-deflected forms. Using density-functional theory, we have found\nthe planar-zigzag structure is the preferred form and upon atomic relaxation,\nthe alternatively-deflected structure attains a structure very similar to the\nplanar-zigzag structure. In order to better understand the atomic origin of the\nferroelectricity in b-PVDF, we have for the first time determined the dynamic\nBorn effective charges (Z*) for the planar-zigzag structure using a Berry-phase\napproach. When compared to their nominal ionic values, the Z* show anomalous\ndifferences. Using these effective charges, we describe the polarity of the\nbonds with b-PVDF and show the extent of atomic-motion-induced (or dynamic)\ncharge transfer within this ferroelectric material. In addition, our effective\ncharges are different to previously-determined Mulliken charges, due to the\ninherent differences between static and dynamic charges."
    },
    {
        "anchor": "Anisotropic Frictional Response of Texture Induced Strained Graphene: Friction-induced energy dissipation impedes the performance of nanoscale\ndevices during their relative motion. Nevertheless, an ingeniously designed\nstructure which utilizes graphene topping can tune the friction force signal by\ninducing local strain. The present work reports capping of graphene over Si\ngrooved surfaces of different pitch lengths from sub-nanoscale (P=40 nm) to a\nquarter of a micron (P= 250 nm). The variation in the pitch lengths induces\ndifferent strains in graphene revealed by scanning probe techniques, Raman\nspectroscopy and molecular dynamics (MD) simulation. The asymmetric straining\nof C-C bonds over the groove architecture is exploited through friction force\nmicroscopy in different directions of orthogonal and parallel to groove axis.\nThe presence of graphene lubricates the textured surface by a factor of 10 and\nperiodically dissipated friction force, which was found to be stochastic over\nthe bare surface. For the first time, we presented transformation of the\nlubrication into an ultra-low friction force by a factor of 20 over the crest\nscanning parallel to the groove axis. Such anisotropy is found to be\ninsignificant at the bare textured system, clearly demonstrating the\nstrain-dependent regulation of friction force. Our results are applicable for\ngraphene, and other 2D materials covered corrugated structures with movable\ncomponents such as NEMS, nanoscale gears and robotics.",
        "positive": "An unconventional platform for two-dimensional Kagome flat bands on\n  semiconductor surfaces: In condensed matter physics, the Kagome lattice and its inherent flat bands\nhave attracted considerable attention for their potential to host a variety of\nexotic physical phenomena. Despite extensive efforts to fabricate thin films of\nKagome materials aimed at modulating the flat bands through electrostatic\ngating or strain manipulation, progress has been limited. Here, we report the\nobservation of a novel $d$-orbital hybridized Kagome-derived flat band in\nAg/Si(111) $\\sqrt{3}\\times\\sqrt{3}$ as revealed by angle-resolved photoemission\nspectroscopy. Our findings indicate that silver atoms on a silicon substrate\nform a Kagome-like structure, where a delicate balance in the hopping\nparameters of the in-plane $d$-orbitals leads to destructive interference,\nresulting in a flat band. These results not only introduce a new platform for\nKagome physics but also illuminate the potential for integrating\nmetal-semiconductor interfaces into Kagome-related research, thereby opening a\nnew avenue for exploring ideal two-dimensional Kagome systems."
    },
    {
        "anchor": "Metal-chalcogen bond-length induced electronic phase transition from\n  semiconductor to topological semimetal in ZrX$_2$ (X = Se and Te): Using angle resolved photoemission spectroscopy (ARPES) and density\nfunctional theory (DFT) calculations we studied the low-energy electronic\nstructure of bulk ZrTe$_2$. ARPES studies on ZrTe$_2$ demonstrate free charge\ncarriers at the Fermi level, which is further confirmed by the DFT\ncalculations. An equal number of hole and electron carrier density estimated\nfrom the ARPES data, points ZrTe$_2$ to a semimetal. The DFT calculations\nfurther suggest a band inversion between Te $p$ and Zr $d$ states at the\n$\\Gamma$ point, hinting at the non-trivial band topology in ZrTe$_2$. Thus, our\nstudies for the first time unambiguously demonstrate that ZrTe$_2$ is a\ntopological semimetal. Also, a comparative band structure study is done on\nZrSe$_2$ which shows a semiconducting nature of the electronic structure with\nan indirect band gap of 0.9 eV between $\\Gamma (A) $ and $M (L)$ high symmetry\npoints. In the below we show that the metal-chalcogen bond-length plays a\ncritical role in the electronic phase transition from semiconductor to a\ntopological semimetal ingoing from ZrSe$_2$ to ZrTe$_2$.",
        "positive": "BaSn$_2$: A new, wide-gap, strong topological insulator: BaSn$_2$ has been shown to form as layers of buckled stanene intercalated by\nbarium ions~\\cite{Kim_2008}. However, despite an apparently straightforward\nsynthesis and significant interest in stanene as a topological material,\nBaSn$_2$ has been left largely unexplored, and has only recently been\nrecognized as a potential topological insulator. Belonging to neither the lead\nnor bismuth chalcogenide families, it would represent a unique manifestation of\nthe topological insulating phase. Here we present a detailed investigation of\nBaSn$_2$, using both {\\it ab initio} and experimental methods. First-principles\ncalculations demonstrate that this overlooked material is a indeed strong\ntopological insulator with a bulk band gap of 360meV, among the largest\nobserved for topological insulators. We characterize the surface state\ndependence on termination chemistry, providing guidance for experimental\nefforts to measure and manipulate its topological properties. Additionally,\nthrough {\\it ab initio} modeling and synthesis experiments we explore the\nstability and accessibility of this phase, revealing a complicated phase\ndiagram that indicates a challenging path to obtaining single crystals."
    },
    {
        "anchor": "Superlattices Consisting of \"Lines\" of Adsorbed Hydrogen Atom Pairs on\n  Graphene: The structures and electron properties of new superlattices formed on\ngraphene by adsorbed hydrogen molecules are theoretically described. It has\nbeen shown that superlattices of the (n, 0) zigzag type with linearly arranged\npairs of H atoms have band structures similar to the spectra of (n, 0) carbon\nnanotubes. At the same time, superlattices of the (n, n) type with a\n\"staircase\" of adsorbed pairs of H atoms are substantially metallic with a high\ndensity of electronic states at the Fermi level and this property distinguishes\ntheir spectra from the spectra of the corresponding (n, n) nanotubes. The\nfeatures of the spectra have the Van Hove form, which is characteristic of each\nindividual superlattice. The possibility of using such planar structures with\nnanometer thickness is discussed.",
        "positive": "Unusual hydrogen atom display in solid acids: Studying crystal structures of superprotonic phases of alkali metal hydrogen\nsulfates and selenates, a very unusual phenomenon has been revealed.\nDynamically disordered hydrogen atoms with low position occupancies are clearly\nseen in corresponding electron density maps. To explain this effect, an idea\nabout a new type of twinning, dynamic twinning, was proposed and discussed."
    },
    {
        "anchor": "Control of electron transport through Fano resonances in molecular wires: Using a first principles approach, we study the electron transport properties\nof two molecules of length 2.5nm which are the building blocks for a new class\nof molecular wires containing fluorenone units. We show that the presence of\nside groups attached to these units leads to Fano resonances close to the Fermi\nenergy. As a consequence electron transport through the molecule can be\ncontrolled either by chemically modifying the side group, or by changing the\nconformation of the side group. This sensitivity, which is not present in\nBreit-Wigner resonances, opens up new possibilities for novel single-molecule\nsensors.",
        "positive": "Possible coexistence of Cycloidal Phases, Magnetic Field Reversal of\n  Polarization and Memory Effect in Multiferroic\n  \\emph{R}$_{0.5}$Dy$_{0.5}$MnO$_3$ (\\emph{R}=Eu and Gd): We report the occurrence of both \\emph{ab} and \\emph{bc} cycloidal ordering\nof Mn-spins at different temperatures and their possible coexistence at low\ntemperatures in the polycrystalline mixed rare-earth compounds,\n\\emph{R}$_{0.5}$Dy$_{0.5}$MnO$_3$ (\\emph{R} = Eu and Gd), which exhibit\nextraordinary magnetoelectric properties. While the polarization of\nGd$_{0.5}$Dy$_{0.5}$MnO$_3$ is comparable to TbMnO$_3$, the compound\nEu$_{0.5}$Dy$_{0.5}$MnO$_3$ shows high value of polarization. However, both of\nthem show giant magnetic tunability and exhibit large magnetocapacitance whose\nsign changes across the two cycloidal ordering temperatures. Intriguingly, the\nelectric polarization can be reversed upon ramping up or ramping down the\nmagnetic field, which has not been observed for any of the \\emph{R}MnO$_3$\nsystem. Most strikingly, these compounds show non-volatile ferroelectric memory\neffect even in the paraelectric and paramagnetic region (T$_C$ $\\leq$ T $\\leq$\n80 K). We attribute these remarkable properties to the coexistence of \\emph{ab}\nand \\emph{bc} cycloidal ordered phases."
    },
    {
        "anchor": "Electric-Field Noise above a Thin Dielectric Layer on Metal Electrodes: The electric-field noise above a layered structure composed of a planar metal\nelectrode covered by a thin dielectric is evaluated and it is found that the\ndielectric film considerably increases the noise level, in proportion to its\nthickness. Importantly, even a thin (mono) layer of a low-loss dielectric can\nenhance the noise level by several orders of magnitude compared to the noise\nabove a bare metal. Close to this layered surface, the power spectral density\nof the electric field varies with the inverse fourth power of the distance to\nthe surface, rather than with the inverse square, as it would above a bare\nmetal surface. Furthermore, compared to a clean metal, where the noise spectrum\ndoes not vary with frequency (in the radio-wave and microwave bands), the\ndielectric layer can generate electric-field noise which scales in inverse\nproportion to the frequency. For various realistic scenarios, the noise levels\npredicted from this model are comparable to those observed in trapped-ion\nexperiments. Thus, these findings are of particular importance for the\nunderstanding and mitigation of unwanted heating and decoherence in\nminiaturized ion traps.",
        "positive": "Inelastic neutron scattering study of phonon density of states in\n  nanostructured Si1xGex thermoelectrics: Inelastic neutron scattering measurements are utilized to explore relative\nchanges in the generalized phonon density of states of nanocrystalline Si1xGex\nthermoelectric materials prepared via ball milling and hot-pressing techniques.\nDynamic signatures of Ge clustering can be inferred from the data by\nreferencing the resulting spectra to a density functional theoretical model\nassuming homogeneous alloying via the virtual-crystal approximation.\nComparisons are also presented between as-milled Si nanopowder and bulk,\npolycrystalline Si where a preferential low-energy enhancement and lifetime\nbroadening of the phonon density of states appear in the nanopowder. Negligible\ndifferences are however observed between the phonon spectra of bulk Si and hot\npressed, nanostructured Si samples suggesting that changes to the single phonon\ndynamics above 4 meV play only a secondary role in the modified heat conduction\nof this compound."
    },
    {
        "anchor": "Transport properties for liquid silicon-oxygen-iron mixtures at Earth's\n  core conditions: We report on the thermal and electrical conductivities of two liquid\nsilicon-oxygen-iron mixtures (Fe$_{0.82}$Si$_{0.10}$O$_{0.08}$ and\nFe$_{0.79}$Si$_{0.08}$O$_{0.13}$), representative of the composition of the\nEarth's outer core at the relevant pressure-temperature conditions, obtained\nfrom density functional theory calculations with the Kubo-Greenwood\nformulation. We find thermal conductivities $k$ =100 (160) W m$^{-1}$ K$^{-1}$,\nand electrical conductivities $\\sigma = 1.1 (1.3) \\times 10^6 \\Omega^{-1}$\nm$^{-1}$ at the top (bottom) of the outer core. These new values are between 2\nand 3 times higher than previous estimates, and have profound implications for\nour understanding of the Earth's thermal history and the functioning of the\nEarth's magnetic field, including rapid cooling rate for the whole core or high\nlevel of radiogenic elements in the core. We also show results for a number of\nstructural and dynamic properties of the mixtures, including the partial radial\ndistribution functions, mean square displacements, viscosities and speeds of\nsound.",
        "positive": "Experimentally derived axial stress- strain relations for\n  two-dimensional materials such as monolayer graphene: A methodology is presented here for deriving true experimental axial\nstress-strain curves in both tension and compression for monolayer graphene\nthrough the shift of the 2D Raman peak that is present in all graphitic\nmaterials. The principle behind this approach is the observation that the shift\nof the 2D wavenumber as a function of strain for different types of PAN based\nfibres is a linear function of their Young's moduli and, hence, the\ncorresponding value of the shift of the 2D Raman peak over axial stress is, in\nfact, a constant. By moving across the length scales we show that this value is\nalso valid at the nanoscale as it corresponds to the in plane breathing mode of\ngraphene that is present in both PAN based fibres and monolayer graphene.\nHence, the values of the shift of the 2D Raman peak can be easily converted to\nvalues of stress in the linear elastic region without the aid of modelling or\nthe need to resort to cumbersome experimental procedures for obtaining the\naxial force transmitted to the material and the cross sectional area of the two\ndimensional membrane."
    },
    {
        "anchor": "Magneto-transport and magneto-optical properties of ferromagnetic\n  (III,Mn)V semicondcutors: a review: Rapid developments in material research of metallic ferromagnetic (III,Mn)V\nsemiconductors over the past few years have brought a much better understanding\nof these complex materials. We review here some of the main developments and\ncurrent understanding of the bulk properties of these systems within the\nmetallic regime, focusing principally on the magneto-transport and\nmagneto-optical properties. Although several theoretical approaches are\nreviewed, the bulk of the review uses the effective Hamiltonian approach, which\nhas proven useful in describing many of these properties namely in (Ga,Mn)As\nand (In,Mn)As. The model assumes a ferromagnetic coupling between Mn d-shell\nlocal moments mediated by holes in the semiconductor valence band.",
        "positive": "A mean field description of jamming in non-cohesive frictionless\n  particulate systems: A theory for kinetic arrest in isotropic systems of repulsive,\nradially-interacting particles is presented that predicts exponents for the\nscaling of various macroscopic quantities near the rigidity transition that are\nin agreement with simulations, including the non-trivial shear exponent. Both\nstatics and dynamics are treated in a simplified, one-particle level\ndescription, and coupled via the assumption that kinetic arrest occurs on the\nboundary between mechanically stable and unstable regions of the static\nparameter diagram. This suggests the arrested states observed in simulations\nare at (or near) an elastic buckling transition. Some additional numerical\nevidence to confirm the scaling of microscopic quantities is also provided."
    },
    {
        "anchor": "Size-independent Shear Band Formation in Amorphous Nanowires made from\n  Simulated Casting: Molecular dynamics simulations indicate that surfaces strongly influence the\nstrain localization behavior of amorphous nanowires in tension. A sample\npreparation routine that simulates casting was employed to facilitate the\nrelaxation of the sample surface. Samples as short as 15 nm (7.5 nm in\ndiameter) form dominant shear bands during deformation. The elastic energy\nrelease during plastic deformation is sufficient to provide the excess\npotential energy required for the shear band nucleation at rather small sample\nsizes. The results show that shear band formation is almost size-independent\nand is bounded only by its own length scale.",
        "positive": "Phase growth control in low temperature PLD Co:TiO2 films by pressure: This paper reports on the structural and optical properties of Co-doped TiO2\nthin films grown onto (0001) Al2O3 substrates by non-reactive pulsed laser\ndeposition (PLD) using argon as buffer gas. It is shown that by keeping\nconstant the substrate temperature at as low as 310 C and varying only the\nbackground gas pressure between 7 Pa and 70 Pa, it is possible to grow either\nepitaxial rutile or pure anatase thin films, as well as films with a mixture of\nboth polymorphs. The optical band gaps of the films are red shifted in\ncomparison to the values usually reported for undoped TiO2, which is consistent\nwith n-type doping of the TiO2 matrix. Such band gap red shift brings the\nabsorption edge of the Co-doped TiO2 films into the visible region, which might\nfavour their photocatalytic activity. Furthermore, the band gap red shift\ndepends on the films phase composition, increasing with the increase of the\nUrbach energy for increasing rutile content."
    },
    {
        "anchor": "Carrier multiplication between interacting nanocrystals for fostering\n  silicon-based photovoltaics: Being a source of clean and renewable energy, the possibility to convert\nsolar radiation in electric current with high efficiency is one of the most\nimportant topics of modern scientific research. Currently the exploitation of\ninteraction between nanocrystals seems to be a promising route to foster the\nestablishment of third generation photovoltaics. Here we adopt a fully\nab-initio scheme to estimate the role of nanoparticle interplay on the carrier\nmultiplication dynamics of interacting silicon nanocrystals. Energy and charge\ntransfer-based carrier multiplication events are studied as a function of\nnanocrystal separation showing benefits induced by the wavefunction sharing\nregime. We prove the relevance of these recombinative mechanisms for\nphotovoltaic applications in the case of silicon nanocrystals arranged in dense\narrays, quantifying at an atomistic scale which conditions maximize the\noutcome.",
        "positive": "Mass Transport Phenomena in a MCFC Cathode: A molten carbonate fuel cell (MCFC) is an electro-chemical energy conversion\ntechnology that runs on natural gas and employs a molten salt electrolyte. In\norder to keep the electrolyte in this state, the cell must be kept at a\ntemperature above 500 C, eliminating the need for precious metals as the\ncatalyst. There has been only a limited amount of research on modelling the\ntransport processes inside this device, mainly due to its restricted\napplicability for mobile applications.\n  In this work, three one-dimensional models of a MCFC cathode are presented\nbased on different types of diffusion and convection. Comparisons between\nmodels are performed so as to assess their validity. Regarding ion transport,\nit is shown that there exists a limiting case for ion migration across the\ncathode that depends on the conductivity for the liquid potential. Finally, an\noptimization of the diffusivity across the cathode is carried out in an attempt\nto increase the cell performance and its longevity."
    },
    {
        "anchor": "Effect of charge carrier relaxation during hopping process on\n  electroluminescence in organic solids: Energetic disorder in disordered organic solids has been found to alter their\nphysical parameters. Here, we have demonstrated, by means of Monte-Carlo\nsimulation and experiments, that the electroluminescence (EL) spectrum is\ndependent on energetic disorder. This dependence has been attributed to the\ncharge carrier relaxation during hopping process. The dependence of EL spectrum\non energetic disorder makes it temperature dependent and temperature dependence\nhas been found to vary with energetic disorder in a variety of materials. The\nsimulation has been performed by taking the relaxation of charge carriers via\ntransport energy in the Gaussian density of states. An analytical equation was\nestablished for spectral shift as a function of transport energy.",
        "positive": "Nodal fermions in a strongly spin-orbit coupled frustrated pyrochlore\n  superconductor: The pyrochlore lattice, a three-dimensional network of corner-sharing\ntetrahedra, is a promising material playground for correlated topological\nphases arising from the interplay between spin-orbit coupling (SOC) and\nelectron-electron interactions. Due to its geometrically frustrated lattice\nstructure, exotic correlated states on the pyrochlore lattice have been\nextensively studied using various spin Hamiltonians in the localized limit. On\nthe other hand, the topological properties of the electronic structure in the\npyrochlore lattice have rarely been explored, due to the scarcity of pyrochlore\nmaterials in the itinerant paramagnetic limit. Here, we explore the topological\nelectronic band structure of pyrochlore superconductor RbBi$_{2}$ using\nangle-resolved photoemission spectroscopy. Thanks to the strong SOC of the Bi\npyrochlore network, we experimentally confirm the existence of\nthree-dimensional (3D) massless Dirac fermions enforced by nonsymmorphic\nsymmetry, as well as a 3D quadratic band crossing protected by cubic\ncrystalline symmetry. Furthermore, we identify an additional 3D linear Dirac\ndispersion associated with band inversion protected by threefold rotation\nsymmetry. These observations reveal the rich non-trivial band topology of\nitinerant pyrochlore lattice systems in the strong SOC regime. Through\nmanipulation of electron correlations and SOC of the frustrated pyrochlore\nlattices, this material platform is a natural host for exotic phases of matter,\nincluding the fractionalized quantum spin Hall effect in the topological Mott\ninsulator phase, as well as axion electrodynamics in the axion insulator phase."
    },
    {
        "anchor": "First-principles calculations of heat capacities of ultrafast\n  laser-excited electrons in metals: Ultrafast laser excitation can induce fast increases of the electronic\nsubsystem temperature. The subsequent electronic evolutions in terms of band\nstructure and energy distribution can determine the change of several\nthermodynamic properties, including one essential for energy deposition; the\nelectronic heat capacity. Using density functional calculations performed at\nfinite electronic temperatures, the electronic heat capacities dependent on\nelectronic temperatures are obtained for a series of metals, including free\nelectron like, transition and noble metals. The effect of exchange and\ncorrelation functionals and the presence of semicore electrons on electronic\nheat capacities are first evaluated and found to be negligible in most cases.\nThen, we tested the validity of the free electron approaches, varying the\nnumber of free electrons per atom. This shows that only simple metals can be\ncorrectly fitted with these approaches. For transition metals, the presence of\nlocalized d electrons produces a strong deviation toward high energies of the\nelectronic heat capacities, implying that more energy is needed to thermally\nexcite them, compared to free sp electrons. This is attributed to collective\nexcitation effects strengthened by a change of the electronic screening at high\ntemperature.",
        "positive": "Comment on \"Raman spectra of misoriented bilayer graphene\": In a recent paper [Phys. Rev. B 78, 113407 (2008)], Poncharal et al. studied\nthe Raman spectra of misoriented bilayer graphene. They found that the\nblueshift of 2D band of misoriented graphene relative to that of single layer\ngraphene shows a strong dependence on the excitation laser energy. The\nblueshift increases with decreasing excitation energy. This finding contradicts\nour explanation of reduction of Fermi velocity of folded/misoriented graphene\n[Ni et al. Phys. Rev. B 77, 235403 (2008)]. In this comment, we present more\nexperimental results from our group as well as from others to show that the\nblueshift is indeed only weakly dependent on excitation energy. We therefore\nsuggest that our explanation of 2D blushift of folded graphene due to reduction\nof Fermi velocity is still valid."
    },
    {
        "anchor": "Everything SAXS: Small-angle scattering pattern collection and\n  correction: For obtaining reliable nanostructural details of large amounts of sample ---\nand if it is applicable --- Small-Angle Scattering (SAS) is a prime technique\nto use. It promises to obtain bulk-scale, statistically sound information on\nthe morphological details of the nanostructure, and has thus led to many a\nresearcher investing their time in it over the last eight decades of\ndevelopment. Due to pressure both from scientists requesting more details on\nincreasingly complex nanostructures, as well as the ever improving\ninstrumentation leaving less margin for ambiguity, small-angle scattering\nmethodologies have been evolving at a high pace over the last few decades.\n  As the quality of any results can only be as good as the data that goes into\nthese methodologies, the improvements in data collection and all imaginable\ndata correction steps are reviewed here. This work is intended to provide a\ncomprehensive overview of all data corrections, to aid the small-angle\nscatterer to decide which are relevant for their measurement and how these\ncorrections are performed. Clear mathematical descriptions of the corrections\nare provided where feasible. Furthermore, as no quality data exists without a\ndecent estimate of its precision, the error estimation and propagation through\nall these steps is provided alongside the corrections. With these data\ncorrections, the collected small-angle scattering pattern can be made of the\nhighest standard allowing for authoritative nanostructural characterisation\nthrough its analysis. A brief background of small-angle scattering, the\ninstrumentation developments over the years, and pitfalls that may be\nencountered upon data interpretations are provided as well.",
        "positive": "Deposition dynamics of Na monomers and dimers on an Ar(001) substrate: We study deposition dynamics of Na and Na$_2$ on an Ar substrate, both\nspecies neutral as well as charged. The system is modeled by a hierarchical\napproach describing the Na valence electrons by time-dependent\ndensity-functional theory while Na core, Ar atoms and their dynamical\npolarizability are treated by molecular dynamics. We explore effects of Na\ncharge and initial kinetic energy of the impinging Na system. We find that\nneutral Na is captured into a loosely bound adsorbate state for sufficiently\nlow impact energy. The charged monomers are more efficiently captured and the\ncation Na$^+$ even penetrates the surface layer. For charged dimers, we come to\ndifferent final configurations depending on the process, direct deposit of\nNa$_2^+$ as a whole, or sequential deposit. In any case, charge dramatically\namplifies the excitation of the matrix, in particular at the side of the Ar\ndipoles. The presence of a charge also enhances the binding to the surface and\nfavours accumulation of larger compounds."
    },
    {
        "anchor": "Antiferromagnetic spin-frustrated layers of corner-sharing Cu4\n  tetrahedra on the kagome lattice in volcanic minerals Cu5O2(VO4)2(CuCl),\n  NaCu5O2(SeO3)2Cl3, and K2Cu5Cl8(OH)4 2H2O: The objective of the present work was to analyze the possibility of\nrealization of quantum spin liquid in three volcanic minerals - averievite\n(Cu5O2(VO4)2(CuCl)), ilinskite (NaCu5O2(SeO3)2Cl3), and avdononite\n(K2Cu5Cl8(OH)4 2H2O - from the crystal chemistry point of view. Based on the\nstructural data, the sign and strength of magnetic interactions have been\ncalculated and the geometric frustrations serving as the main reason of the\nexistence of spin liquids have been investigated. According to our\ncalculations, the magnetic structures of averievite and ilinskite are composed\nof antiferromagnetic (AFM) spin-frustrated layers of corner-sharing Cu4\ntetrahedra on the kagome lattice. However, the direction of nonshared corners\nof tetrahedra is different in them. The oxygen ions centering the OCu4\ntetrahedra in averievite and ilinskite provide the main contribution to the\nformation of AFM interactions along the tetrahedra edges. The local electric\npolarization in averievite and the possibility of spin configuration\nfluctuations due to vibrations of tetrahedra-centering oxygen ions have been\ndiscussed. The existence of structural phase transitions accompanied with\nmagnetic transitions was assumed in ilinskite because of the effect of a lone\nelectron pair by Se4+ ions. As was demonstrated through comparison of\naverievite and avdoninite, at the removal of centering oxygen ions from\ntetrahedra, the magnetic structure of the pyrochlore layer present in\naverievite transformed into an openwork curled net with large cells woven from\ncorner-sharing open AFM spin-frustrated tetrahedra ('butterflies'} in\navdoninite.",
        "positive": "Two-Dimensional Transition Metal Dichalcogenides-Based Counter\n  Electrodes for Dye-Sensitized Solar Cells: Dye-sensitized solar cells (DSSCs) are gaining considerable interest as\nalternatives to the semiconductor-based thin film solar cells. The noble metal\nplatinum (Pt) is conventionally used as counter electrode (CE) material for\nfabricating DSSCs. Since Pt is expensive and scarce, new materials have been\nexplored to develop cost-effective Pt-free counter electrodes for DSSCs.\nTwo-dimensional (2D) graphene-based counter electrodes have achieved the\nhighest known power conversion efficiency ({\\eta}) of 13%, which has stimulated\nresearch activities in 2D layered transition metal dichalcogenides (TMDs) for\ndeveloping Pt-free DSSCs. In this review, progress made on alternative counter\nelectrodes for fabricating low-cost Pt-free DSSCs, based on earth-abundant 2D\nTMDs including MoS2, WS2, TiS2, FeS2, CoS2, NiS2, SnS2, MoSe2, NbSe2, TaSe2,\nNiSe2, FeSe2, CoSe2, Bi2Se3 and their based composites, are discussed and\nsummarized. Also, the considerable progress made on thin films of MoS2 and MoS2\nbased carbon, graphene, carbon nanotubes (CNTs), carbon nanofibers (CNFs), and\npoly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) composites\nas efficient counter electrodes (CEs) for DSSCs are discussed, in terms of\ntheir electrochemical and photovoltaic properties. At present, PCE values\nhigher than that of standard Pt CE have been recorded for a number of TMD-based\nCEs, which include MoS2 and MoSe2/thin films deposited on Mo foil, MoS2/CNTs,\nMoS2/graphene, MoS2/carbon, MoSe2/PEDOT:PSS, NbSe2, FeS2, FeSe2 nanosheets,\nTiS2/graphene, and NiS2/graphene hybrid systems in DSSCs, for the reduction of\ntriiodide (I3-) to iodide (I-). The highest PCE ({\\eta}=10.46%) versus Pt CE\n({\\eta}=8.25%) at 1 Sun (100 mW/cm2, AM 1.5G) was measured for DSSCs having a\nlow cost and flexible CoSe2/carbon-nanoclimbing wall counter electrode\ndeposited on a nickel foam."
    },
    {
        "anchor": "Combined ab initio and empirical model of the thermal conductivity of\n  uranium, uranium-zirconium, and uranium-molybdenum: In this work we developed a practical and general modeling approach for\nthermal conductivity of metals and metal alloys that integrates ab initio and\nsemiempirical physics-based models to maximize the strengths of both\ntechniques. The approach supports creation of highly accurate, mechanistic, and\nextensible thermal conductivity modeling of alloys. The model was demonstrated\non {\\alpha}-U and U-rich U-Zr and U-Mo alloys, which are potential fuels for\nadvanced nuclear reactors. The safe use of U-based fuels requires quantitative\nunderstanding of thermal transport characteristics of the fuel. The model\nincorporated both phonon and electron contributions, displayed good agreement\nwith experimental data over a wide temperature range, and provided insight into\nthe different physical factors that govern the thermal conductivity under\ndifferent temperatures. This model is general enough to incorporate more\ncomplex effects like additional alloying species, defects, transmutation\nproducts, and noble gas bubbles to predict the behavior of complex metallic\nalloys like U-alloy fuel systems under burnup.",
        "positive": "Linking Properties to Microstructure in Liquid Metal Embedded Elastomers\n  via Machine Learning: Liquid metals (LM) are embedded in an elastomer matrix to obtain soft\ncomposites with unique thermal, dielectric, and mechanical properties. They\nhave applications in soft robotics, biomedical engineering, and wearable\nelectronics. By linking the structure to the properties of these materials, it\nis possible to perform material design rationally. Liquid-metal embedded\nelastomers (LMEEs) have been designed for targeted electro-thermo-mechanical\nproperties by semi-supervised learning of structure-property (SP) links in a\nvariational autoencoder network (VAE). The design parameters are the\nmicrostructural descriptors that are physically meaningful and have affine\nrelationships with the synthetization of the studied particulate composite. The\nmachine learning (ML) model is trained on a generated dataset of\nmicrostructural descriptors with their multifunctional property quantities as\ntheir labels. Sobol sequence is used for in-silico Design of Experiment (DoE)\nby sampling the design space to generate a comprehensive dataset of 3D\nmicrostructure realizations via a packing algorithm. The mechanical responses\nof the generated microstructures are simulated using a previously developed\nFinite Element (FE) model, considering the surface tension induced by LM\ninclusions, while the linear thermal and dielectric constants are homogenized\nwith the help of our in-house Fast Fourier Transform (FFT) package. Following\nthe training by minimization of an appropriate loss function, the VAE encoder\nacts as the surrogate of numerical solvers of the multifunctional\nhomogenizations, and its decoder is used for the material design. Our results\nindicate the satisfactory performance of the surrogate model and the inverse\ncalculator with respect to high-fidelity numerical simulations validated with\nLMEE experimental results."
    },
    {
        "anchor": "Revealing the dark side of a bright exciton polariton condensate: Condensation of bosons causes spectacular phenomena such as superfluidity or\nsuperconductivity. Understanding the nature of the condensed particles is\ncrucial for active control of such quantum phases. Fascinating possibilities\nemerge from condensates of light-matter coupled excitations, such as exciton\npolaritons, photons hybridized with hydrogen-like bound electron-hole pairs. So\nfar, only the photon component has been resolved, while even the mere existence\nof excitons in the condensed regime has been challenged. Here we trace the\nmatter component of polariton condensates by monitoring intra-excitonic\nterahertz transitions. We study how a reservoir of optically dark excitons\nforms and feeds the degenerate state. Unlike atomic gases, the atom-like\ntransition in excitons is dramatically renormalized upon macroscopic ground\nstate population. Our results establish fundamental differences between\npolariton condensation and photon lasing and open possibilities for coherent\ncontrol of condensates.",
        "positive": "Nitridation of InP(1 0 0) surface studied by synchrotron radiation: The nitridation of InP(1 0 0) surfaces has been studied using synchrotron\nradiation photoemission. The samples were chemically cleaned and then ion\nbombarded, which cleaned the surface and also induced the formation of metallic\nindium droplets. The nitridation with a Glow Discharge Cell (GDS) produced\nindium nitride by reaction with these indium clusters. We used the In 4d and P\n2p core levels to monitor the chemical state of the surface and the coverage of\nthe species present. We observed the creation of In-N and P-N bonds while the\nIn-In metallic bonds decrease which confirm the reaction between indium\nclusters and nitrogen species. A theoretical model based on stacked layers\nallows us to assert that almost two monolayers of indium nitride are produced.\nThe effect of annealing on the nitridated layers at 450 $^\\circ$C has also been\nanalysed. It appears that this system is stable up to this temperature, well\nabove the congruent evaporation temperature (370 $^\\circ$C) of clean InP(1 0\n0): no increase of metallic indium bonds due to decomposition of the substrate\nis detected as shown in previous works [L. Bideux, Y. Ould-Metidji, B. Gruzza,\nV. Matolin, Surf. Interface Anal. 34 (2002) 712] studying the InP(1 0 0)\nsurfaces."
    },
    {
        "anchor": "Dangling bonds on the Cl- and Br-terminated Si(100) surfaces: Halogen monolayer on a silicon surface is attracting active attention for\napplications in electronic device fabrication with individual impurities. To\ncreate a halogen mask for the impurities incorporation, it is desirable to be\nable to remove a single halogen atom from the surface. We report the desorption\nof individual halogen atoms from the Si(100)-2x1-Cl and -Br surfaces in a\nscanning tunneling microscope (STM). Silicon dangling bonds (DBs) formed on the\nSi surface after halogen desorption were investigated using STM and the density\nfunctional theory. Three charge states: positive, neutral, and negative were\nidentified. Our results show that the charge states of DBs can be manipulated,\nwhich will allow to locally tune the reactivity of the Cl- and Br-terminated\nSi(100) surfaces.",
        "positive": "Simultaneous multi-region background subtraction for core-level EEL\n  spectra: We present a multi-region extension of standard power-law background\nsubtraction for core-level EEL spectra to improve the robustness of background\nremoval. This method takes advantage of the post-edge shape of core-loss EEL\nedges to enable simultaneous and co-dependent fitting of pre- and post-edge\nbackground regions. This method also produces simultaneous and consistent\nbackground removal from multiple edges in a single EEL spectrum. The stability\nof this method with respect to the fitting energy window is also discussed."
    },
    {
        "anchor": "Electronically driven collapse of the bulk modulus in $\u03b4$-plutonium: Plutonium metal exhibits an anomalously large softening of its bulk modulus\nat elevated temperatures that is made all the more extraordinary by the finding\nthat it occurs irrespective of whether the thermal expansion coefficient is\npositive, negative or zero --- representing an extreme departure from\nconventional Gr\\\"{u}neisen scaling. We show here that the cause of this\nsoftening is the compressibility of plutonium's thermally excited electronic\nconfigurations, which has thus far not been considered in thermodynamic models.\nWe show that when compressible electronic configurations are thermally\nactivated, they invariably give rise to a softening of bulk modulus regardless\nof the sign their contribution to the thermal expansion. The electronically\ndriven softening of the bulk modulus is shown to be in good agreement with\nelastic moduli measurements performed on the gallium-stabilized $\\delta$ phase\nof plutonium over a range of temperatures and compositions, and is shown to\ngrow rapidly at small concentrations of gallium and at high temperatures, where\nit becomes extremely sensitive to hydrostatic pressure.",
        "positive": "Solvation of Lithium Ion in Dimethoxyethane and Propylene Carbonate: Solvation of the lithium ion (Li+) in dimethoxyethane (DME) and propylene\ncarbonate (PC) is of scientific significance and urgency in the context of\nlithium-ion batteries. I report PM7-MD simulations on the composition of Li+\nsolvation shells (SH) in a few DME/PC mixtures. The equimolar mixture features\npreferential solvation by PC, in agreement with classical MD studies. However,\none DME molecule is always present in the first SH, supplementing the cage\nformed by five PC molecules. As PC molecules get removed, DME gradually\nsubstitutes vacant places. In the PC-poor mixtures, an entire SH is populated\nby five DME molecules."
    },
    {
        "anchor": "Electronic structure of $\u03b2$-SiAlON: effect of varying Al/O\n  concentration at finite temperatures relevant for thermal quenchin: $\\beta$-Si$_{6-z}$Al$_{z}$O$_{z}$N$_{8-z}$ is a prominent example of systems\nsuitable as hosts for creating materials for light-emitting diodes. In this\nwork, the electronic structure of a series of ordered and disordered\n$\\beta$-Si$_{6-z}$Al$_{z}$O$_{z}$N$_{8-z}$ systems is investigated by means of\nab initio calculations, using the FLAPW and the Green function KKR methods.\nFinite temperature effects are included within the alloy analogy model. We\nfound that the trends with the Al/O doping are similar for ordered and\ndisordered structures. The electronic band gap decreases with increasing $z$ by\nabout 1 eV when going from $z$=0 to $z$=2. The optical gap decreases\nanalogously as the electronic band gap. The changes in the density of states\n(DOS) at Si and N atoms introduced by doping $\\beta$-Si$_{3}$N$_{4}$ with Al\nand O are comparable to the DOS at Al and O atoms themselves. The bottom of the\nconduction band in $\\beta$-Si$_{6-z}$Al$_{z}$O$_{z}$N$_{8-z}$ is formed by\nextended states residing on all atomic types. Increasing the temperature leads\nto a shift of the bottom of the conduction band to lower energies. The amount\nof this shift increases with increasing doping $z$.",
        "positive": "The making of ferromagnetic Fe doped ZnO nano-clusters: In this letter, the authors present a study of the energetics and magnetic\ninteractions in Fe doped ZnO clusters by ab-initio density functional\ncalculations. The results indicate that defects under suitable conditions can\ninduce ferromagnetic interactions between the dopant Fe atoms whereas\nantiferromagnetic coupling dominates in a neutral defect-free cluster. The\ncalculations also reveal an unusual ionic state of the dopant Fe atom residing\nat the surface of the cluster, a feature that is important to render the\ncluster ferromagnetic."
    },
    {
        "anchor": "Defects-Assisted Piezoelectric Response in Liquid Exfoliated MoS2\n  Nanosheets: We report piezoelectric response in liquid phase exfoliated MoS2 nanosheets\nwith desired structure and morphology. The piezoelectric effect in liquid phase\nexfoliated few layers of MoS2 flakes is interesting as it may allow the\nscalable fabrication of electronic devices such as self-powered electronics,\npiezoelectric transformers, antennas and more. The piezo force microscopy (PFM)\nmeasurements were used to quantify the amplitude and phase loop, which shows\nstrong piezoelectric coefficient. Herein, the piezoelectric response in few\nlayers of MoS2 is attributed to the defects formed in it during the synthesis\nprocedure. The presence of defects is confirmed by XPS analysis",
        "positive": "Self-stacked 1$\\mathrm{T}$-1$\\mathrm{H}$ layers in 6$\\mathrm{R}$-NbSeTe\n  and the emergence of charge and magnetic correlations due to ligand disorder: The emergence of correlated phenomena arising from the combination of\n1$\\mathrm{T}$ and 1$\\mathrm{H}$ van der Waals layers is the focus of intense\nresearch. Here, we synthesize a novel self-stacked 6$\\mathrm{R}$ phase in\nNbSeTe, showing a perfect alternating 1T and 1H layers that grow coherently\nalong the c-direction, as revealed by scanning transmission electron\nmicroscopy. Angle resolved photoemission spectroscopy shows a mixed\ncontribution of the trigonal and octahedral Nb bands to the Fermi level.\nDiffuse scattering reveals temperature-independent short-range charge\nfluctuations with propagation vector $\\mathrm{q_{CO}}$=(0.25,0), derived from\nthe condensation of a longitudinal mode in the 1T layer. We observe that ligand\ndisorder quenches the formation of a charge density wave. Magnetization\nmeasurements suggest the presence of an inhomogeneous, short-range magnetic\norder, further supported by the absence of a clear phase transition in the\nspecific heat. These experimental analyses in combination with \\textit{ab\ninitio} calculations indicate that the ground state of 6$\\mathrm{R}$-NbSeTe is\ndescribed by a statistical distribution of short-range charge-modulated and\nspin-correlated regions driven by ligand disorder. Our results devise a route\nto synthesize 1$\\mathrm{T}$-1$\\mathrm{H}$ self-stacked bulk heterostructures to\nstudy emergent phases of matter."
    },
    {
        "anchor": "Competing magnetism in $\u03c0$ electrons in graphene with a single carbon\n  vacancy: One intriguing finding in graphene is the vacancy-induced magnetism that\nhighlights the interesting interaction between local magnetic moments and\nconduction electrons. Within density functional theory, the current\nunderstanding of the ground state is that a Stoner instability gives rise to\nferromagnetism of $\\pi$ electrons aligned with the localized moment of a\n$\\sigma$ dangling bond and the induced $\\pi$ magnetic moments vanish at low\nvacancy concentrations. However, the observed Kondo effect suggests that $\\pi$\nelectrons around the vacancy should antiferromagnetically couple to the local\nmoment and carry non-vanishing moments. Here we propose that a phase possessing\nboth significant out-of-plane displacements and $\\pi$ bands with\nantiferromagnetic coupling to the localized $\\sigma$ moment is the ground\nstate. With the features we provide, it is possible for spin-resolved STM, STS,\nand ARPES measurements to verify the newly proposed phase.",
        "positive": "Tunable adsorption on carbon nanotubes: We investigated the adsorption of a single atom, hydrogen and aluminum, on\nsingle wall carbon nanotubes from first-principles. The adsorption is\nexothermic, and the associated binding energy varies inversely as the radius of\nthe zigzag tube. We found that the adsorption of a single atom and related\nproperties can be modified continuously and reversibly by the external radial\ndeformation. The binding energy on the high curvature site of the deformed tube\nincreases with increasing radial deformation. The effects of curvature and\nradial deformation depend on the chirality of the tube."
    },
    {
        "anchor": "Node-to-segment and node-to-surface interface finite elements for\n  fracture mechanics: The topologies of existing interface elements used to discretize cohesive\ncracks are such that they can be used to compute the relative displacements\n(displacement discontinuities) of two opposing segments (in 2D) or of two\nopposing facets (in 3D) belonging to the opposite crack faces and enforce the\ncohesive traction-separation relation. In the present work we propose a novel\ntype of interface element for fracture mechanics sharing some analogies with\nthe node-to-segment (in 2D) and with the node-to-surface (in 3D) contact\nelements. The displacement gap of a node belonging to the finite element\ndiscretization of one crack face with respect to its projected point on the\nopposite face is used to determine the cohesive tractions, the residual vector\nand its consistent linearization for an implicit solution scheme. The following\nadvantages with respect to classical interface finite elements are\ndemonstrated: (i) non-matching finite element discretizations of the opposite\ncrack faces is possible; (ii) easy modelling of cohesive cracks with\nnon-propagating crack tips; (iii) the internal rotational equilibrium of the\ninterface element is assured. Detailed examples are provided to show the\nusefulness of the proposed approach in nonlinear fracture mechanics problems.",
        "positive": "Positive electron affinity of interfacial region in Polyethylene-MgO\n  nanocomposite dielectric: Polymer-based nanocomposite dielectrics are expected to become essential in\nfuture generations of high voltage electrical insulation. However, the physics\nbehind their performance is not yet understood. Here we investigate electronic\nproperties of the interfacial area in magnesium oxide-polyethylene\nnanocomposite. We use density functional theory to calculate densities of\nstates for MgO (100) and hydroxylated MgO (111) interfaces with polyethylene.\nWe evaluate the role of silicon-based nanoparticle surface modification at the\nelectronic level and propose a new theory for charge trapping in\nnanocomposites."
    },
    {
        "anchor": "The origin of the E+ transition in GaAsN alloys: Optical properties of GaAsN system with nitrogen concentrations in the range\nof 0.9-3.7% are studied by full-potential LAPW method in a supercell approach.\nThe E+ transition is identified by calculating the imaginary part of the\ndielectric function. The evolution of the energy of this transition with\nnitrogen concentration is studied and the origin of this transition is\nidentified by analyzing the contributions to the dielectric function from\ndifferent band combinations. The L_1c-derived states are shown to play an\nimportant role in the formation of the E+ transition, which was also suggested\nby recent experiments. At the same time the nitrogen-induced modification of\nthe first conduction band of the host compound are also found to contribute\nsignificantly to the E+ transition. Further, the study of several model\nsupercells demonstrated the significant influence of the nitrogen potential on\nthe optical properties of the GaAsN system.",
        "positive": "Adatoms and nanoengineering of carbon: We present a new and general mechanism for inter-conversion of carbon\nstructures via a catalytic exchange process, which operates under conditions of\nFrenkel pair generation. The mechanism typically lowers reaction barriers by a\nfactor of four compared to equivilent uncatalysed reactions. We examine the\nrelevance of this mechanism for fullerene growth, carbon onions and nanotubes,\nand dislocations in irradiated graphite."
    },
    {
        "anchor": "Visualization of steps and surface reconstructions in Helium Ion\n  Microscopy with atomic precision: Helium Ion Microscopy is known for its surface sensitivity and high lateral\nresolution. Here, we present results of a Helium Ion Microscopy based\ninvestigation of a surface confined alloy of Ag on Pt(111). Based on a change\nof the work function of 25\\,meV across the atomically flat terraces we can\ndistinguish Pt rich from Pt poor areas and visualize the single atomic layer\nhigh steps between the terraces. Furthermore, dechanneling contrast has been\nutilized to measure the periodicity of the hcp/fcc pattern formed in the 2--3\nlayers thick Ag/Pt alloy film. A periodicity of 6.65\\,nm along the\n$\\langle\\overline{11}2\\rangle$ surface direction has been measured. In terms of\ncrystallography a hcp domain is obtained through a lateral displacement of a\npart of the outermost layer by $1/\\sqrt{3}$ of a nearest neighbour spacing\nalong $\\langle\\overline{11}2\\rangle$. This periodicity is measured with atomic\nprecision: coincidence between the Ag and the Pt lattices is observed for 23 Ag\natoms on 24 Pt atoms. The findings are perfectly in line with results obtained\nwith Low Energy Electron Microscopy and Phase Contrast Atomic Force Microscopy.",
        "positive": "Rapid oxygen exchange between hematite and water vapor: Oxygen exchange at oxide/liquid and oxide/gas interfaces is important in\ntechnology and environmental studies, as it is closely linked to both catalytic\nactivity and material degradation. The atomic-scale details are mostly unknown,\nhowever, and are often ascribed to poorly defined defects in the crystal\nlattice. Here we show that even thermodynamically stable, well-ordered surfaces\ncan be surprisingly reactive. Specifically, we show that all the 3-fold\ncoordinated lattice oxygen atoms on a defect-free single-crystalline r-cut\n(1-102) surface of hematite ({\\alpha}-Fe2O3) are exchanged with oxygen from\nsurrounding water vapor within minutes at temperatures below 70 {\\deg}C, while\nthe atomic-scale surface structure is unperturbed by the process. A similar\nbehavior is observed after liquid water exposure, but the experimental data\nclearly show most of the exchange happens during desorption of the final\nmonolayer, not during immersion. Density functional theory computations show\nthat the exchange can happen during on-surface diffusion, where the cost of the\nlattice oxygen extraction is compensated by the stability of an HO-HOH-OH\ncomplex. Such insights into lattice oxygen stability are highly relevant for\nmany research fields ranging from catalysis and hydrogen production to\ngeochemistry and paleoclimatology."
    },
    {
        "anchor": "Dependence of response functions and orbital functionals on occupation\n  numbers: Explicitly orbital-dependent approximations to the exchange-correlation\nenergy functional of density functional theory typically not only depend on the\nsingle-particle Kohn-Sham orbitals but also on their occupation numbers in the\nground state Slater determinant. The variational calculation of the\ncorresponding exchange-correlation potentials with the Optimized Effective\nPotential (OEP) method therefore also requires a variation of the occupation\nnumbers with respect to a variation in the effective single-particle potential,\nwhich is usually not taken into account. Here it is shown under which\ncircumstances this procedure is justified.",
        "positive": "Anisotropic Electron Spin Lifetime in (In,Ga)As/GaAs (110) Quantum Wells: Anisotropic electron spin lifetimes in strained undoped (In,Ga)As/GaAs (110)\nquantum wells of different width and height are investigated by time-resolved\nFaraday rotation and time-resolved transmission and are compared to the\n(001)-orientation. From the suppression of spin precession, the ratio of\nin-plane to out-of-plane spin lifetimes is calculated. Whereas the ratio\nincreases with In concentration in agreement with theory, a surprisingly high\nanisotropy of 480 is observed for the broadest quantum well, when expressed in\nterms of spin relaxation times."
    },
    {
        "anchor": "Quantum Materials for Spin and Charge Conversion: Spintronics aims to utilize the spin degree of freedom for information\nstorage and computing applications. One major issue is the generation and\ndetection of spins via spin and charge conversion. Quantum materials have\nrecently exhibited many unique spin-dependent properties, which can be used as\npromising material candidates for efficient spin and charge conversion. Here,\nwe review recent findings concerning spin and charge conversion in quantum\nmaterials, including Rashba interfaces, topological insulators, two-dimensional\nmaterials, superconductors, and non-collinear antiferromagnets. Important\nprogress in using quantum materials for spin and charge conversion could pave\nthe way for developing future spintronics devices.",
        "positive": "Room temperature spin-orbit torque efficiency and magnetization\n  switching in SrRuO3-based heterostructures: Spin-orbit torques (SOTs) from transition metal oxides (TMOs) in conjunction\nwith magnetic materials have recently attracted tremendous attention for\nrealizing high-efficient spintronic devices. SrRuO3 is a promising candidate\namong TMOs due to its large and tunable SOT-efficiency as well as high\nconductivity and chemical stability. However, a further study for benchmarking\nthe SOT-efficiency and realizing SOT-driven magnetization switching in SrRuO3\nis still highly desired so far. Here, we systematically study the SOT\nproperties of high-quality SrRuO3 thin film heterostructuring with different\nmagnetic alloys of both IMA and PMA configuration by the harmonic Hall voltage\ntechnique. Our results indicate that SrRuO3 possesses pronounced SOT-efficiency\nof about 0.2 at room temperature regardless of the magnetic alloys, which is\ncomparable to typical heavy metals (HMs). Furthermore, we achieve SOT-driven\nmagnetization switching with a low threshold current density of 3.8x10^10\nA/m^2, demonstrating the promising potential of SrRuO3 for practical devices.\nBy making a comprehensive comparison with HMs, our work unambiguously\nbenchmarks the SOT properties and concludes the advantages of SrRuO3, which may\nbring more diverse choices for SOT applications by utilizing hybrid-oxide/metal\nand all-oxide systems."
    },
    {
        "anchor": "NV- - N+ pair centre in 1b diamond: The study establishes that the degree of optically induced spin polarization\nthat can be achieved for NV$^- $in 1b diamond is limited by the concentration\nof single substitutional nitrogen, N$^0$ . The polarization of the individual\nNV centres in the diamond is dependent on the separation of the NV$^-$ and the\nnitrogen donor. When the NV$^-$ - N$^+$ pair separation is large the properties\nof the pair will be as for single sites and a high degree of spin polarization\nattainable. When the separation decreases the emission is reduced, the lifetime\nshortened and the spin polarization downgraded. The deterioration occurs as a\nconsequence of electron tunneling in the excited state from NV$^-$ to N$^+$ and\nresults in an optical cycle that includes NV$^0$. The tunneling process is\nlinear in optical excitation and more prevalent the closer the N$^+$ is to the\nNV$^-$ centre. However, the separation between the NV$^-$ and its donor N$^+$\ncan be effected by light through the excitation of NV$^-$ and/or ionization of\nN$^0$. The optical excitation that creates the spin polarization can also\nmodify the sample properties and during excitation creates charge dynamics. The\nconsequence is that the magnitude of spin polarization, the spin relaxation and\ncoherence times T$_1$ and T$_2$ have a dependence on the nitrogen concentration\nand on the excitation wavelength. The adjacent N$^+$ gives an electric field\nthat Stark shifts the NV$^-$ transitions and for an ensemble results in line\nbroadening. It is observation of changes of these Stark induced effects that\nallow the variation in NV$^-$ - N$^+$ separation to be monitored. Spectroscopic\nmeasurements including that of the varying line widths are central to the\nstudy. They are made at low temperatures and include extensive measurements of\nthe NV$^-$ optical transition at 637 nm, the infrared transition at 1042 nm and\nODMR at 2.87 GHz.",
        "positive": "Bayesian optimization of discrete dislocation plasticity of\n  two-dimensional precipitation hardened crystals: Discovering relationships between materials' microstructures and mechanical\nproperties is a key goal of materials science. Here, we outline a strategy\nexploiting Bayesian optimization to efficiently search the multidimensional\nspace of microstructures, defined here by the size distribution of precipitates\n(fixed impurities or inclusions acting as obstacles for dislocation motion)\nwithin a simple two-dimensional discrete dislocation dynamics model. The aim is\nto design a microstructure optimizing a given mechanical property, e.g.,\nmaximizing the expected value of shear stress for a given strain. The problem\nof finding the optimal discretized shape for a distribution involves a norm\nconstraint, and we find that sampling the space of possible solutions should be\ndone in a specific way in order to avoid convergence problems. To this end, we\npropose a general mathematical approach that can be used to generate trial\nsolutions uniformly at random while enforcing an Euclidean norm constraint.\nBoth equality and inequality constraints are considered. A simple technique can\nthen be used to convert between Euclidean and other Lebesgue $p$-norm (the\n1-norm in particular) constrained representations. Considering different\ndislocation-precipitate interaction potentials, we demonstrate the convergence\nof the algorithm to the optimal solution and discuss its possible extensions to\nthe more complex and realistic case of three-dimensional dislocation systems\nwhere also the optimization of precipitate shapes could be considered."
    },
    {
        "anchor": "Band engineering in dilute nitride and bismide semiconductor lasers: Highly mismatched semiconductor alloys such as GaNAs and GaBiAs have several\nnovel electronic properties, including a rapid reduction in energy gap with\nincreasing x and also, for GaBiAs, a strong increase in spin orbit- splitting\nenergy with increasing Bi composition. We review here the electronic structure\nof such alloys and their consequences for ideal lasers. We then describe the\nsubstantial progress made in the demonstration of actual GaInNAs telecomm\nlasers. These have characteristics comparable to conventional InP-based\ndevices. This includes a strong Auger contribution to the threshold current. We\nshow, however, that the large spin-orbit-splitting energy in GaBiAs and GaBiNAs\ncould lead to the suppression of the dominant Auger recombination loss\nmechanism, finally opening the route to efficient temperature-stable telecomm\nand longer wavelength lasers with significantly reduced power consumption.",
        "positive": "Coexisting ferroelectric and antiferroelectric phases in dipole ordered\n  substances. Material properties and possible applications: Comprehensive review of investigations of substances with a small difference\nin the energies of the ferroelectric and antiferroelectric types of dipole\nordering is presented. Detailed analysis of the stability of homogeneous phases\nand conditions for existence of the inhomogeneous state of the substance\ncontaining domains of the coexisting ferroelectric and antiferroelectric phases\nis presented. It is shown that the interaction of locally separated domains of\nthe ferroelectric and antiferroelectric phases stabilizes an inhomogeneous\nstate of these materials. The analysis of physical phenomena caused by the\npresence of domains of the coexisting ferroelectric and antiferroelectric\nphases in different dipole ordered substances is presented. Peculiarities of\nbehavior of the systems with the inhomogeneous state of coexisting phases under\nthe action of changing external thermodynamic parameters (temperature,\npressure, electric field, and chemical composition) are analyzed and their\nimportance for applications of these materials is discussed."
    },
    {
        "anchor": "Hidden, entangled and resonating order: In condensed matter systems, the atoms, electrons or spins can sometimes\narrange themselves in ways that result in unexpected properties but that cannot\nbe detected by conventional experimental probes. Several historical and\ncontemporary examples of such hidden orders are known and more are awaiting\ndiscovery, perhaps in the form of more complex composite, entangled or\ndynamical hidden orders.",
        "positive": "Raman studies on amorphous carbon layers - Raman-Untersuchungen von\n  amorphen Kohlenstoffschichten: Raman spectroscopic study of amorphous carbon layers for two different\nexcitation wavelengths at room temperature. The amount of sp3 bondings is\nestimated to about 10% for both samples, evaluated from the ratio of the D- and\nG-Raman line intensities. The properties of the bondings in the two samples are\ndiscussed.\n  Raman-spektroskopische Untersuchungen von amorphen Kohlenstoffschichten fuer\nzwei unterschiedliche Anregungswellenlaengen bei Raumtemperatur. Der\nsp3-Bindungsanteil is zu 10% fuer beide Proben bestimmt worden, ermittelt aus\ndem Intensitaetsverhaeltnis der D- and G-Raman-Linien. Die Eigenschaften der\nBindungen in den beiden untersuchten Proben werden diskutiert."
    },
    {
        "anchor": "Dynamics of two coupled vortices in a spin valve nanopillar excited by\n  spin transfer torque: We investigate the dynamics of two coupled vortices driven by spin transfer.\nWe are able to independently control with current and perpendicular field, and\nto detect, the respective chiralities and polarities of the two vortices. For\ncurrent densities above $J=5.7*10^7 A/cm^2$, a highly coherent signal\n(linewidth down to 46 kHz) can be observed, with a strong dependence on the\nrelative polarities of the vortices. It demonstrates the interest of using\ncoupled dynamics in order to increase the coherence of the microwave signal.\nEmissions exhibit a linear frequency evolution with perpendicular field, with\ncoherence conserved even at zero magnetic field.",
        "positive": "Magnetization dynamics and damping due to electron-phonon scattering in\n  a ferrimagnetic exchange model: We present a microscopic calculation of magnetization damping for a magnetic\n\"toy model.\" The magnetic system consists of itinerant carriers coupled\nantiferromagnetically to a dispersionless band of localized spins, and the\nmagnetization damping is due to coupling of the itinerant carriers to a phonon\nbath in the presence of spin-orbit coupling. Using a mean-field approximation\nfor the kinetic exchange model and assuming the spin-orbit coupling to be of\nthe Rashba form, we derive Boltzmann scattering integrals for the distributions\nand spin coherences in the case of an antiferromagnetic exchange splitting,\nincluding a careful analysis of the connection between lifetime broadening and\nthe magnetic gap. For the Elliott-Yafet type itinerant spin dynamics we extract\ndephasing and magnetization times T_1 and T_2 from initial conditions\ncorresponding to a tilt of the magnetization vector, and draw a comparison to\nphenomenological equations such as the Landau-Lifshitz or the Gilbert damping.\nWe also analyze magnetization precession and damping for this system including\nan anisotropy field and find a carrier mediated dephasing of the localized spin\nvia the mean-field coupling."
    },
    {
        "anchor": "Boundaries for efficient use of electron vortex beams to measure\n  magnetic properties: Development of experimental techniques for characterization of magnetic\nproperties at high spatial resolution is essential for progress in\nminiaturization of magnetic devices, for example, in data storage media.\nInelastic scattering of electron vortex beams (EVB) was recently reported to\ncontain atom-specific magnetic information. We have developed a theoretical\ndescription of inelastic scattering of EVB on crystals and performed\nsimulations for EVB of different diameters. We show that use of an EVB wider\nthan an interatomic distance does not provide any advantage over an ordinary\nconvergent beam without angular momentum. On the other hand, in the atomic\nresolution limit, electron energy loss spectra measured by EVB are strongly\nsensitive to the spin and orbital magnetic moments of studied matter, when\nchanneling through or very close to the atomic columns. Our results demonstrate\nthe boundaries for efficient use of EVB in measurement of magnetic properties.",
        "positive": "Machine-learning Driven Synthesis of TiZrNbHfTaC5 High-Entropy Carbide: Synthesis of high-entropy carbides (HEC) requires high temperatures that can\nbe provided by electric arc plasma method. However, the formation temperature\nof a single-phase sample remains unknown. Moreover, under some temperatures\nmulti-phase structures can emerge. In this work we developed an approach for a\ncontrollable synthesis of HEC TiZrNbHfTaC5 based on theoretical and\nexperimental techniques. We used canonical Monte Carlo (CMC) simulations with\nthe machine learning interatomic potentials to determine the temperature\nconditions for the formation of single-phase and multi-phase samples. In full\nagreement with the theory, the single-phase sample, produced with electric arc\ndischarge, was observed at 2000 K. Below 1200 K the sample decomposed into\n(Ti-Nb-Ta)C and a mixture of (Zr-Hf-Ta)C, (Zr-Nb-Hf)C, (Zr-Nb)C, and (Zr-Ta)C.\nOur results demonstrate the conditions for the formation of HEC and we\nanticipate that our approach can pave the way towards targeted synthesis of\nmulticomponent materials."
    },
    {
        "anchor": "Effect of Long-Range Coulomb Interaction on NMR Shift in Massless Dirac\n  Electrons of Organic Conductor: The nuclear magnetic resonance (NMR) with the site-dependent shift, at low\ntemperatures is examined for a massless Dirac electrons in the organic\nconductor, alpha-(BEDT-TTF)_2I_3, where the sites of the four molecules in the\nunit cell are given by A (= A'), B, and C. The Dirac cone exists within an\nenergy of 0.01 eV between the conduction and valence bands. The magnetic\nresponse function is calculated by taking account of the long-range Coulomb\ninteraction and electron doping. Calculating the interaction within the first\norder in the perturbation, the chemical potential is determined\nself-consistently, and the self-energy and vertex corrections are taken to\nsatisfy the Ward identity. The site-dependent shift is calculated at low\ntemperatures of 0.0002 < T < 0.002 (T is temperature in the unit of eV) by\ncorrectly treating the wave function of the Dirac cone. At lower (higher)\ntemperatures the self-energy (vertex) correction of the shift at all sites\nexcept for B is dominant and the sign is negative (positive), while the sign of\nthe correction at the B site is always negative. For moderate doping, the shift\nas a function of T takes a minimum. The relevance of the shift to the\nexperiment is discussed.",
        "positive": "Tuning the p-type Schottky barrier in 2D metal/semiconductor interface:\n  boron-sheet/\\mose, and /\\wse: The electronic and the structural properties of two dimensional van der Waals\nmetal/semiconductor heterostructures have been investigated through\nfirst-principles calculations. We have considered the recently synthesized\nborophene [Science {\\bf 350}, 1513 (2015)], and the planar boron sheets (S1 and\nS2) [Nature Chemistry {\\bf 8}, 563 (2016)] as the 2D metal layer, and the\ntransition metal dichalcogenides (TMDCs) \\mose, and \\wse\\ as the semiconductor\nmonolayer. We find that the energetic stability of those 2D metal/semiconductor\nheterojunctions is mostly ruled by the vdW interactions; however, chemical\ninteractions also take place in borophene/TMDC. The electronic charge transfers\nat the metal/semiconductor interface has been mapped, where we find a a net\ncharge transfer from the TMDCs to the boron sheets. Further electronic\nstructure calculations reveal that the metal/semiconductor interfaces, composed\nby planar boron sheets S1 and S2, present a p-type Schottky barrier which can\nbe tuned to a p-type ohmic contact upon an external electric field."
    },
    {
        "anchor": "Can the Ferroelectric Soft Mode Trigger an Antiferromagnetic Phase\n  Transition?: Type-II multiferroics, where spin interactions induce a ferroelectric\npolarization, are interesting for new device functionalities due to large\nmagnetoelectric coupling. We report on a new type of multiferroicity in the\nquadruple-perovskite\n$\\text{BiMn}_{\\text{3}}\\text{Cr}_{\\text{4}}\\text{O}_{\\text{12}}$, where an\nantiferromagnetic phase is induced by the structural change at the\nferroelectric phase transition. The displacive nature of the ferroelectric\nphase transition at 125 K, with a crossover to an order-disorder mechanism, is\nevidenced by a polar soft phonon in the THz range and a central mode.\nDielectric and pyroelectric studies show that the ferroelectric critical\ntemperature corresponds to the previously reported N\\'eel temperature of the\n$\\text{Cr}^{\\text{3+}}$ spins. An increase in ferroelectric polarization is\nobserved below 48 K, coinciding with the N\\'eel temperature of the\n$\\text{Mn}^{\\text{3+}}$ spins. This increase in polarization is attributed to\nan enhanced magnetoelectric coupling, as no change in the crystal symmetry\nbelow 48 K is detected from infrared and Raman spectra.",
        "positive": "Rapid Size-Controlled Synthesis of Dextran-Coated, 64Cu-Doped Iron Oxide\n  Nanoparticles: Research into developing dual modality probes enabled for magnetic resonance\nimaging (MRI) and positron emission tomography (PET) has been on the rise\nrecently due to the potential to combine the high resolution of MRI and the\nhigh sensitivity of PET. Current synthesis techniques for developing multimodal\nprobes is largely hindered in part by prolonged reaction times during\nradioisotope incorporation - leading to a weakening of the radioactivity. Along\nwith a time-efficient synthesis, the resulting products must fit within a\ncritical size range (between 20-100nm) to increase blood retention time. In\nthis work, we describe a novel, rapid, microwave-based synthesis technique to\ngrow dextran-coated iron oxide nanoparticles doped with copper (DIO/Cu).\nTraditional methods for coprecipitation of dextran-coated iron oxide\nnanoparticles require refluxing for 2 hours and result in approximately 50 nm\ndiameter particles. We demonstrate that microwave synthesis can produce 50 nm\nnanoparticles with 5 minutes of heating. We discuss the various parameters used\nin the microwave synthesis protocol to vary the size distribution of DIO/Cu,\nand demonstrate the successful incorporation of 64Cu into these particles with\nthe aim of future use for dual-mode MR/PET imaging."
    },
    {
        "anchor": "Adsorption and Vibrational Spectroscopy of CO on the Surface of MgO from\n  Periodic Local Coupled-Cluster Theory: The adsorption of CO on the surface of MgO has long been a model problem in\nsurface chemistry. Here, we report periodic Gaussian-based calculations for\nthis problem using second-order perturbation theory (MP2) and coupled-cluster\ntheory with single and double excitations (CCSD) and perturbative triple\nexcitations [CCSD(T)], with the latter two performed using a recently developed\nextension of the local natural orbital approximation to problems with periodic\nboundary conditions. The low cost of periodic local correlation calculations\nallows us to calculate the full CCSD(T) binding curve of CO approaching the\nsurface of MgO (and thus the adsorption energy) and the two-dimensional\npotential energy surface (PES) as a function of the distance from the surface\nand the CO stretching coordinate. From the PES, we obtain the fundamental\nvibrational frequency of CO on MgO, whose shift from the gas phase value is a\ncommon experimental probe of surface adsorption. We find that CCSD(T) correctly\npredicts a positive frequency shift upon adsorption of\n$+14.7~\\textrm{cm}^{-1}$, in excellent agreement with the experimental shift of\n$+14.3~\\textrm{cm}^{-1}$. We use our CCSD(T) results to assess the accuracy of\nMP2, CCSD, and several density functional theory (DFT) approximations,\nincluding exchange correlation functionals and dispersion corrections. We find\nthat MP2 and CCSD yield reasonable binding energies and frequency shifts,\nwhereas many DFT calculations overestimate the magnitude of the adsorption\nenergy by $5$ -- $15$~kJ/mol and predict a negative frequency shift of about\n$-20~\\textrm{cm}^{-1}$, which we attribute to self-interaction-induced\ndelocalization errors that are mildly ameliorated with hybrid functionals. Our\nfindings highlight the accuracy and computational efficiency of the periodic\nlocal correlation for the simulation of surface chemistry with accurate\nwavefunction methods.",
        "positive": "High-performance $n$-type organic field-effect transistors with ionic\n  liquid gates: High-performance $n$-type organic field-effect transistors were developed\nwith ionic-liquid gates and N,N$^\"$-bis(n-alkyl)-(1,7 and\n1,6)-dicyanoperylene-3,4:9,10-bis(dicarboximide)s single-crystals. Transport\nmeasurements show that these devices reproducibly operate in ambient atmosphere\nwith negligible gate threshold voltage and mobility values as high as 5.0\ncm$^2$/Vs. These mobility values are essentially identical to those measured in\nthe same devices without the ionic liquid, using vacuum or air as the gate\ndielectric. Our results indicate that the ionic-liquid and $n$-type organic\nsemiconductor interfaces are suitable to realize high-quality $n$-type organic\ntransistors operating at small gate voltage, without sacrificing electron\nmobility."
    },
    {
        "anchor": "Group V Mixing Effects in the Structural and Optical Properties of\n  (ZnSi)1/2(P)1/4(As)1/4: We present {\\it ab initio} total energy and band structure calculations based\non Density Funtional Theory (DFT) within the Local Density Aproximation (LDA)\non group-V mixing effects in the optoelectronic material\n$(ZnSi)_{1/2}P_{1/4}As_{3/4}$. This compound has been recently proposed by\ntheoretical design as an optically active material in the 1.5 $\\mu$m (0.8 eV)\nfiber optics frequency window and with a monolithic integration with the Si\n(001) surface. Our results indicate that alloy formation in the group V planes\nwould likely occur at typical growth conditions. In addition, desired features\nsuch as in-plane lattice constant and energy gap are virtually unchanged and\nthe optical oscillator strength for band-to-band transitions is increased by a\nfactor of 6 due to alloying.",
        "positive": "Dimensional crossover of thermal transport in few-layer graphene\n  materials: Graphene, in addition to its unique electronic and optical properties,\nrevealed unusually high thermal conductivity. The fact that thermal\nconductivity of large enough graphene sheets should be higher than that of\nbasal planes of bulk graphite was predicted theoretically by Klemens. However,\nthe exact mechanisms behind drastic alteration of material's intrinsic ability\nto conduct heat as its dimensionality changes from 2-D to 3-D remain elusive.\nRecent availability of high-quality few-layer graphene materials allowed us to\nstudy dimensional crossover experimentally. Here we show that the\nroom-temperature thermal conductivity changes from K~3000 W/mK to 1500 W/mK as\nthe number of atomic plains in few-layer graphene increases from 2 to 4. We\nexplained the observed evolution from 2-D to bulk by the cross-plane coupling\nof the low-energy phonons and corresponding changes in the phonon Umklapp\nscattering. The obtained results shed light on heat conduction in\nlow-dimensional materials and may open up few-layer graphene applications in\nthermal management of nanoelectronics."
    },
    {
        "anchor": "Competing Mechanisms between Dislocation and Phase Transformation in\n  Plastic Deformation of Single Crystalline Yttria-Stabilized Tetragonal\n  Zirconia Nanopillars: Molecular dynamics (MD) is employed to investigate the plastic deformation\nmechanisms of single crystalline yttria-stabilized tetragonal zirconia (YSTZ)\nnanopillars under uniaxial compression. Simulation results show that the\nnanoscale plastic deformation of YSTZ is strongly dependent on the\ncrystallographic orientation of zirconia nanopillars. For the first time, the\nexperimental explored tetragonal to monoclinic phase transformation is\nreproduced by MD simulations in some particular loading directions. Three\ndistinct mechanisms of dislocation, phase transformation, and a combination of\ndislocation and phase transformation are identified when applying compressive\nloading along different directions. The strength of zirconia nanopillars\nexhibits a sensitive behavior depending on the failure mechanisms, such that\nthe dislocation-mediated deformation leads to the lowest strength, while the\nphase transformation-dominated deformation results in the highest strength.",
        "positive": "Argon bubble formation in tantalum oxide-based films for gravitational\n  wave interferometer mirrors: The argon content of titanium dioxide doped tantalum pentoxide thin films was\nquantified in a spatially resolved way using HAADF images and DualEELS. Films\nannealed at 300$^{\\circ}$C, 400$^{\\circ}$C and 600$^{\\circ}$C were investigated\nto see if there was a relationship between annealing temperature and bubble\nformation. It was shown using HAADF imaging that argon is present in most of\nthese films and that bubbles of argon start to form after annealing at\n400$^{\\circ}$C and coarsen after annealing at 600$^{\\circ}$C. A semi-empirical\nstandard was created for the quantification using argon data from the EELS\natlas and experimental data scaled using a Hartree Slater cross section. The\ndensity and pressure of argon within the bubbles was calculated for 35 bubbles\nin the 600$^{\\circ}$C sample. The bubbles had a mean diameter, density and\npressure of 22\\r{A}, 870kg/m$^3$ and 400MPa, respectively. The pressure was\ncalculated using the Van der Waals equation. The bubbles may affect the\nproperties of the films, which are used as optical coatings for mirrors in\ngravitational wave detectors. This spatially resolved quantification technique\ncan be readily applied to other small noble gas bubbles in a range of\nmaterials."
    },
    {
        "anchor": "On the separation of Hall and Ohmic nonlinear responses: The symmetric and antisymmetric parts of the linear conductivity describe the\ndissipative (Ohmic) and nondissipative (Hall) parts of the current. The Hall\ncurrent is always transverse to the applied electric field regardless of its\norientation; the Ohmic current is purely longitudinal in cubic crystals, but in\nlower-symmetry crystals it has a transverse component whenever the field is not\naligned with a principal axis. In this work, we extend that analysis beyond the\nlinear regime. We consider all possible ways of partitioning the current at any\norder in the electric field without taking symmetry into account, and find that\nthe Hall vs Ohmic decomposition is the only one that satisfies certain basic\nrequirements. A general prescription is given for achieving that decomposition,\nand the case of the quadratic conductivity is analyzed in detail. By performing\na symmetry analysis we find that in five of the 122 magnetic point groups the\nquadratic dc conductivity is purely Ohmic and even under time reversal, a type\nof response that is entirely disorder mediated.",
        "positive": "Stabilization of Co oxide during oxygen evolution in alkaline media by\n  the introduction of Mn oxide: Improving the stability of electrocatalysts for the oxygen evolution reaction\n(OER) through materials design has received less attention than improving their\ncatalytic activity. We explored the effect of Mn addition to a cobalt oxide for\nstabilizing the catalyst by comparing Na-containing CoOx and (Co0.7Mn0.3)Ox\nfilms electrodeposited in alkaline solution. The obtained disordered films were\nclassified as layered oxides using X-ray absorption spectroscopy (XAS). The\nCoOx films showed a constant decrease in the catalytic activity during cycling,\nconfirmed by oxygen detection, while that of (Co0.7Mn0.3)Ox slightly increased\nas measured by electrochemical metrics. These trends were rationalized based on\nXAS analysis of the metal oxidation states, which were Co2.8+ and Mn3.7+ near\nthe surface after cycling. Thus, adding Mn to CoOx successfully stabilized the\ncatalyst material and its activity during OER cycling. The development of\nstabilization approaches is essential to extend the durability of OER\ncatalysts."
    },
    {
        "anchor": "Symmetry of Magnetically Ordered Quasicrystals: The notion of magnetic symmetry is reexamined in light of the recent\nobservation of long range magnetic order in icosahedral quasicrystals [Charrier\net al., Phys. Rev. Lett. 78, 4637 (1997)]. The relation between the symmetry of\na magnetically-ordered (periodic or quasiperiodic) crystal, given in terms of a\n``spin space group,'' and its neutron diffraction diagram is established. In\ndoing so, an outline of a symmetry classification scheme for magnetically\nordered quasiperiodic crystals is provided. Predictions are given for the\nexpected diffraction patterns of magnetically ordered icosahedral crystals,\nprovided their symmetry is well described by icosahedral spin space groups.",
        "positive": "Photoinduced magnetism in the ferromagnetic semiconductors: We study the enhancement of the magnetic transition temperature $T_c$ due to\nincident light in ferromagnetic semiconductors such as EuS. The photoexcited\ncarriers mediate an extra ferromagnetic interaction due to the coupling with\nthe localized magnetic moments. The Hamiltonian consists of a Heisenberg model\nfor the localized moments and an interaction term between the photoexcited\ncarriers and the localized moments. The model predicts a small enhancement of\nthe transition temperature in semi-quantitative agreement with the experiments."
    },
    {
        "anchor": "Current-induced torque originating from orbital current: The electrical manipulation of magnetization by current-induced spin torques\nhas given access to realize a plethora of ultralow power and fast spintronic\ndevices such as non-volatile magnetic memories, spin-torque nano-oscillators,\nand neuromorphic computing devices. Recent advances have led to the notion that\nrelativistic spin-orbit coupling is an efficient source for current-induced\ntorques, opening the field of spin-orbitronics. Despite the significant\nprogress, however, the fundamental mechanism of magnetization manipulation, the\nrequirement of spin currents in generating current-induced torques, has\nremained unchanged. Here, we demonstrate the generation of current-induced\ntorques without the use of spin currents. By measuring the current-induced\ntorque for naturally-oxidized-Cu/ferromagnetic-metal bilayers, we observed an\nexceptionally high effective spin Hall conductivity at low temperatures despite\nthe absence of strong spin-orbit coupling. Furthermore, we found that the\ndirection of the torque depends on the choice of the ferromagnetic layer, which\ncounters the conventional understanding of the current-induced torque. These\nunconventional features are best interpreted in terms of an orbital counterpart\nof the spin torque, an orbital torque, which arises from the orbital Rashba\neffect and orbital current. These findings will shed light on the underlying\nphysics of current-induced magnetization manipulation, potentially altering the\nlandscape of spin-orbitronics.",
        "positive": "Direct observation of ultrafast long-range charge separation at\n  polymer:fullerene heterojunctions: In polymeric semiconductors, charge carriers are polarons, which means that\nthe excess charge deforms the molecular structure of the polymer chain that\nhosts it. This effect results in distinctive signatures in the vibrational\nmodes of the polymer. We probe polaron photo- generation dynamics at\npolymer:fullerene heterojunctions by monitoring its time-resolved\nresonance-Raman spectrum following ultrafast photoexcitation. We conclude that\npolarons emerge within 200 fs, which is nearly two orders of magnitude faster\nthan exciton localisation in the neat polymer film. Surprisingly, further\nvibrational evolution on <50-ps timescales is modest, indicating that the\npolymer conformation hosting nascent polarons is not signif- icantly different\nfrom that in equilibrium. This suggests that charges are free from their mutual\nCoulomb potential, under which vibrational dynamics would report charge-pair\nrelaxation. Our work addresses current debates on the photocarrier generation\nmechanism at organic semiconductor heterojunctions, and is, to our knowledge,\nthe first direct probe of molecular conformation dynamics during this\nfundamentally important process in these materials."
    },
    {
        "anchor": "Distinguishing two-component anomalous Hall effect from topological Hall\n  effect: In transport, the topological Hall effect (THE) presents itself as\nnon-monotonic features (or humps and dips) in the Hall signal and is widely\ninterpreted as a sign of chiral spin textures, like magnetic skyrmions.\nHowever, when anomalous Hall effect (AHE) is also present, the co-existence of\ntwo AHEs could give rise to similar artifacts, making it difficult to\ndistinguish between genuine THE with AHE and two-component AHE. Here we confirm\ngenuine THE with AHE by means of transport and magneto-optical Kerr effect\n(MOKE) microscopy, in which magnetic skyrmions are directly observed, and find\nthat genuine THE occurs in the transition region of the AHE. In sharp contrast,\nthe artifact \"THE\", or two-component AHE occurs well beyond the saturation of\nthe \"AHE component\" (under the false assumption of THE+AHE). Furthermore, we\ndistinguish artifact \"THE\" from genuine THE by three methods: 1. Minor loops,\n2. Temperature dependence, 3. Gate dependence. Minor loops of genuine THE with\nAHE are always within the full loop, while minor loops of the artifact \"THE\"\nmay reveal a single loop that cannot fit into the \"AHE component\". Besides, the\ntemperature or gate dependence of the artifact \"THE\" may also be accompanied by\na polarity change of the \"AHE component\", as the non-monotonic features vanish,\nwhile the temperature dependence of genuine THE with AHE reveals no such\nchange. Our work may help future researchers to exercise cautions and use these\nmethods to examine carefully in order to ascertain genuine THE.",
        "positive": "Atomic-Scale Tailoring of Chemisorbed Atomic Oxygen on Epitaxial\n  Graphene for Graphene-Based Electronic Devices: Graphene, with its unique band structure, mechanical stability, and high\ncharge mobility, holds great promise for next-generation electronics.\nNevertheless, its zero band gap challenges the control of current flow through\nelectrical gating, consequently limiting its practical applications. Recent\nresearch indicates that atomic oxygen can oxidize epitaxial graphene in a\nvacuum without causing unwanted damage. In this study, we have investigated the\neffects of chemisorbed atomic oxygen on the electronic properties of epitaxial\ngraphene, using scanning tunneling microscopy (STM). Our findings reveal that\noxygen atoms effectively modify the electronic states of graphene, resulting in\na band gap at its Dirac point. Furthermore, we demonstrate that it is possible\nto selectively induce desorption or hopping of oxygen atoms with atomic\nprecision by applying appropriate bias sweeps with an STM tip. These results\nsuggest the potential for atomic-scale tailoring of graphene oxide, enabling\nthe development of graphene-based atomic-scale electronic devices."
    },
    {
        "anchor": "Accurate molecular dynamics and nuclear quantum effects at low cost by\n  multiple steps in real and imaginary time: using density functional theory to\n  accelerate wavefunction methods: The development and implementation of increasingly accurate methods for\nelectronic structure calculations mean that, for many atomistic simulation\nproblems, treating light nuclei as classical particles is now one of the most\nserious approximations. Even though recent developments have significantly\nreduced the overhead for modelling the quantum nature of the nuclei, the cost\nis still prohibitive when combined with advanced electronic structure methods.\nHere we present how multiple time step integrators can be combined with\nring-polymer contraction techniques (effectively, multiple time stepping in\nimaginary time) to reduce virtually to zero the overhead of modelling nuclear\nquantum effects, while describing inter-atomic forces at high levels of\nelectronic structure theory. This is demonstrated for a combination of MP2 and\nsemi-local DFT applied to the Zundel cation. The approach can be seamlessly\ncombined with other methods to reduce the computational cost of path integral\ncalculations, such as high-order factorizations of the Boltzmann operator, or\ngeneralized Langevin equation thermostats.",
        "positive": "Large linear magnetoresistance in the Dirac semimetal TlBiSSe: The mixed-chalcogenide compound TlBiSSe realizes a three-dimensional (3D)\nDirac semimetal state. In clean, low-carrier-density single crystals of this\nmaterial, we found Shubnikov-de Haas oscillations to signify its 3D Dirac\nnature. Moreover, we observed very large linear magnetoresistance (MR)\napproaching 10,000% in 14 T at 1.8 K, which diminishes rapidly above 30 K. Our\nanalysis of the magnetotransport data points to the possibility that the linear\nMR is fundamentally governed by the Hall field; although such a situation has\nbeen predicted for highly-inhomogeneous systems, inhomogeneity does not seem to\nplay an important role in TlBiSSe. Hence, the mechanism of large linear MR is\nan intriguing open question in a clean 3D Dirac system."
    },
    {
        "anchor": "Breakdown of the Born-Oppenheimer approximation in LiH and LiD: We compute the ab-initio electron density beyond the Born-Oppenheimer\napproximation in crystalline LiH and LiD. We verify the breakdown of the\nBorn-Oppenheimer approximation, as earlier suggested on experimental grounds.\nThe results indicate the existence of beyond Born-Oppenheimer effects in solids\nat normal pressures and suggest that these effects can be significant also in\nsolids containing elements other than hydrogen as well.",
        "positive": "Indirect Mn-Mn pair interaction induces pseudogap in density of states\n  of Al(Si)-Mn approximants: The effect on the electronic structure of an indirect Mn-Mn interaction\nmediated by the valence states and the sp-d hybridisation is presented. In\nAl(rich)-Mn phases related to quasicrystals (Al12Mn, o-Al6Mn, alpha-Al9Mn2Si),\nthis indirect interaction creates a Hume-Rothery pseudogap in the density of\nstates together with a minimisation of the band energy. It is shown that Mn-Mn\ninteraction up to distances around 1.0-2.0 nm plays an essential role in\nstabilizing related quasicrystal structures."
    },
    {
        "anchor": "Electronic transitions of single silicon vacancy centers in the\n  near-infrared spectral region: Photoluminescence (PL) spectra of single silicon vacancy (SiV) centers\nfrequently feature very narrow room temperature PL lines in the near-infrared\n(NIR) spectral region, mostly between 820 nm and 840 nm, in addition to the\nwell known zero-phonon-line (ZPL) at approx. 738 nm [E. Neu et al., Phys. Rev.\nB 84, 205211 (2011)]. We here exemplarily prove for a single SiV center that\nthis NIR PL is due to an additional purely electronic transition (ZPL). For the\nNIR line at 822.7 nm, we find a room temperature linewidth of 1.4 nm (2.6 meV).\nThe line saturates at similar excitation power as the ZPL. ZPL and NIR line\nexhibit identical polarization properties. Cross-correlation measurements\nbetween the ZPL and the NIR line reveal anti-correlated emission and prove that\nthe lines originate from a single SiV center, furthermore indicating a fast\nswitching between the transitions (0.7 ns). g(2) auto-correlation measurements\nexclude that the NIR line is a vibronic sideband or that it arises due to a\ntransition from/to a meta-stable (shelving) state.",
        "positive": "Exploring GaN crystallographic orientation disparity and its origin on\n  bare and partly graphene-covered $m$-plane sapphire substrates: The crystallographic orientation of 3D materials grown over 2D\nmaterial-covered substrates is one of the critical factors in discerning the\ntrue growth mechanism among competing possibilities, including remote epitaxy,\nvan der Waals epitaxy, and pinhole-seeded lateral epitaxy also known as\nthru-hole epitaxy. However, definitive identification demands meticulous\ninvestigation to accurately interpret experimentally observed crystallographic\norientations, as misinterpretation can lead to mistaken conclusions regarding\nthe underlying growth mechanism. In this study, we demonstrate that GaN domains\nexhibit orientation disparities when grown on both bare and partly\ngraphene-covered $m$-plane sapphire substrates. Comprehensive measurements of\ncrystallographic orientation unambiguously reveal that GaN domains adopt (100)\nand (103) orientations even when grown under identical growth conditions on\nbare and partly graphene-covered $m$-plane sapphire substrates, respectively.\nParticularly, high-resolution transmission electron microscopy unequivocally\nestablishes that GaN grown over partly graphene-covered $m$-plane sapphire\nsubstrates started to nucleate on the exposed sapphire surface. Our research\nelucidates that crystallographic orientation disparities can arise even from\nthru-hole epitaxy, challenging the commonly accepted notion that such\ndisparities cannot be attributed to thru-hole epitaxy when grown under\nidentical growth conditions."
    },
    {
        "anchor": "Pade spectroscopy of structural correlation functions: application to\n  liquid gallium: We propose the new method of fluid structure investigation which is based on\nnumerical analytical continuation of structural correlation functions with Pade\napproximants. The method particularly allows extracting hidden structural\nfeatures of non-ordered condensed matter systems from experimental diffraction\ndata. The method has been applied to investigating the local order of liquid\ngallium which has non-trivial stricture in both the liquid and solid states.\nProcessing the correlation functions obtained from molecular dynamic\nsimulations, we show the method proposed reveals non-trivial structural\nfeatures of liquid gallium such as the spectrum of length-scales and the\nexistence of different types of local clusters in the liquid.",
        "positive": "Solid state phase transformation kinetics in Zr-base alloys: We present a kinetic model for solid state phase transformation\n(alpha<-->beta) of common zirconium alloys used as fuel cladding material in\nlight water reactors. The model computes the relative amounts of beta or alpha\nphase fraction as a function of time or temperature in the alloys. The model\naccounts for the influence of excess oxygen (due to oxidation) and hydrogen\nconcentration (due to hydrogen pickup) on phase transformation kinetics. Two\nvariants of the model denoted by A and B are presented. Model A is suitable for\nsimulation of laboratory experiments in which the heating/cooling rate is\nconstant and is prescribed. Model B is more generic. We compare the results of\nour model computations, for both A and B variants, with accessible experimental\ndata reported in the literature covering heating/cooling rates of up to 100\nK/s. The results of our comparison are satisfactory, especially for model A.\nOur model B is intended for implementation in fuel rod behavior computer\nprograms, applicable to a reactor accident situation, in which the Zr-based\nfuel cladding may go through alpha<-->beta phase transformation."
    },
    {
        "anchor": "Neutron Diffuse Scattering from Polar Nanoregions in the Relaxor\n  Pb(Mg1/3Nb2/3)O3: We have studied the neutron diffuse scattering in the relaxor PMN. The\ndiffuse scattering appears around the Burns temperature (~620K), indicating its\norigin from the polar nanoregions (PNR). While the relative diffuse intensities\nare consistent with previous reports, they are entirely different from those of\nthe lowest-energy TO phonon. Because of that, it has been considered that this\nTO mode could not be the ferroelectric soft mode. Recently, a neutron\nscattering study has unambiguously shown that the TO mode does soften on\ncooling. If the diffuse scattering in PMN originates from the soft mode\ncondensation, then the atomic displacements must satisfy the center of mass\ncondition. But, the atomic displacements determined from diffuse scattering\nintensities do not fulfill this condition. To resolve this contradiction, we\npropose a simple model in which the total atomic displacement consists of two\ncomponents: $\\delta_{CM}$ is created by the soft mode condensation, satisfying\nthe center of mass condition, and, $\\delta_{shift}$ represents a uniform\ndisplacement of the PNR along their polar direction relative to the surrounding\n(unpolarized) cubic matrix. Within this framework, we can successfully describe\nthe neutron diffuse scattering intensities observed in PMN.",
        "positive": "Electronic Structures of MgB{$_2$} under Uniaxial and Hydrostatic\n  Compression: Electronic and lattice properties of MgB{$_2$} under uniaxial and hydrostatic\ncompression are calculated. Lattice properties are optimized automatically by\nusing the first-principles molecular dynamics (FPMD) method. Features of the\nelectronic band structures under uniaxial and hydrostatic compression are quite\ndifferent each other."
    },
    {
        "anchor": "Suppressing twin formation in Bi2Se3 thin films: The microstructure of Bi2Se3 topological-insulator thin films grown by\nmolecular beam epitaxy on InP(111)A and InP(111)B substrates that have\ndifferent surface roughnesses has been studied in detail using X-ray\ndiffraction, X-ray reflectivity, atomic force microscopy and probe-corrected\nscanning transmission electron microscopy. The use of a rough Fe-doped\nInP(111)B substrate results in complete suppression of twin formation in the\nBi2Se3 thin films and a perfect interface between the films and their\nsubstrates. The only type of structural defects that persist in the \"twin-free\"\nfilms is an antiphase domain boundary, which is associated with variations in\nsubstrate height. It is also shown that the substrate surface termination\ndetermines which family of twin domains dominates.",
        "positive": "Ab initio Calculations of Multilayer Relaxations of Stepped Cu Surfaces: We present trends in the multilayer relaxations of several vicinals of\nCu(100) and Cu(111) of varying terrace widths and geometry. The electronic\nstructure calculations are based on density functional theory in the local\ndensity approximation with norm-conserving, non-local pseudopotentials in the\nmixed basis representation. While relaxations continue for several layers, the\nmajor effect concentrates near the step and corner atoms. On all surfaces the\nstep atoms contract inwards, in agreement with experimental findings.\nAdditionally, the corner atoms move outwards and the atoms in the adjacent\nchain undergo large inward relaxation. Correspondingly, the largest contraction\n(4%) is in the bond length between the step atom and its bulk nearest neighbor\n(BNN), while that between the corner atom and BNN is somewhat enlarged. The\nsurface atoms also display changes in registry of upto 1.5%. Our results are in\ngeneral in good agreement with LEED data including the controversial case of\nCu(511). Subtle differences are found with results obtained from semi-empirical\npotentials."
    },
    {
        "anchor": "Mechanisms of near-surface structural evolution in nanocrystalline\n  materials during sliding contact: The wear-driven structural evolution of nanocrystalline Cu was simulated with\nmolecular dynamics under constant normal loads, followed by a quantitative\nanalysis. While the microstructure far away from the sliding contact remains\nunchanged, grain growth accompanied by partial dislocations and twin formation\nwas observed near the contact surface, with more rapid coarsening promoted by\nhigher applied normal loads. The structural evolution continues with increasing\nnumber of sliding cycles and eventually saturates to a stable distinct layer of\ncoarsened grains, separated from the finer matrix by a steep gradient in grain\nsize. The coarsening process is balanced by the rate of material removal when\nthe normal load is high enough. The observed structural evolution leads to an\nincrease in hardness and decrease in friction coefficient, which also saturate\nafter a number of sliding cycles. This work provides important mechanistic\nunderstanding of nanocrystalline wear, while also introducing a methodology for\natomistic simulations of cyclic wear damage under constant applied normal\nloads.",
        "positive": "Epitaxial growth and properties of La0.7Sr0.3MnO3 thin films with\n  micrometer wide atomic terraces: La0.7Sr0.3MnO3 (LSMO) films with extraordinarily wide atomic terraces are\nepitaxially grown on SrTiO3 (100) substrates by pulsed laser deposition. Atomic\nforce microscopy measurements on the LSMO films show that the atomic step is ~\n4 {\\AA} and the atomic terrace width is more than 2 micrometers. For a 20\nmonolayers (MLs) LSMO film, the magnetization is determined to be 255 +- 15\nemu/cm3 at room temperature, corresponding to 1.70 + - 0.11 Bohr magneton per\nMn atom. As the thickness of LSMO increases from 8 MLs to 20 MLs, the critical\nthickness for the temperature dependent insulator-to-metal behavior transition\nis shown to be 9 MLs. Furthermore, post-annealing in oxygen environment\nimproves the electron transport and magnetic properties of the LSMO films."
    },
    {
        "anchor": "Controlled nucleation and growth of CdS nanoparticles in a polymer\n  matrix: The nucleation and growth of CdS nanoparticles within a polymer matrix was\nfollowed by in-situ synchrotron X-ray diffraction. The nanoparticles form by\neffect of the thermolysis of thiolate precursors at temperatures between 200\nand 300 Celsius degrees. Above 240 Celsius degrees the precursor decomposition\nis complete and CdS nanoparticles grow in the polymer matrix forming a\nnanocomposite with interesting optical properties. The nanoparticle structural\nproperties (size and crystal structure) depend on the annealing\ntemperature.(abridged version)",
        "positive": "Pressure effect on the topologically nontrivial electronic state and\n  transport of lutecium monobismuthide: Rare-earth monopnictides are predicted to be nontrivial semimetal candidates\nand show pressure-induced superconductivity. Here, we grow LuBi single crystal\nand study the magnetization, transport behaviors and electronic band structures\nto reveal its topological semimetal feature and superconductivity under\npressure. At 0 GPa, the quantum oscillations indicate that there are several\ntopologically nontrivial carrier pockets around the Fermi level, among which\nthe hole ones are isotropic in shape, while the electron ones are anisotropic\nand responsible for the angular magnetoresistance. Upon compression, the\nsuperconductivity emerges in the titled compound, showing a similar pressure\ndependence as that observed in LaBi. Our calculation suggests that the\nelectronic band structures are robust at low- and high-pressure respectively\nand thus the topological features are always preserved. Besides, the nearly\npressure-independent density of state in LuBi indicates that the conventional\nelectron-phonon coupling appears to play a minor role in the superconductivity."
    },
    {
        "anchor": "Phonon-Magnon coupling in CoF$_2$ investigated by time-of-flight neutron\n  spectroscopy: We report the results of inelastic neutron scattering investigation on the\nmodel antiferromagnet CoF$_2$ by time-of-flight neutron spectroscopy. We\nmeasured the details of the scattering function $S(Q,\\omega)$ as a function of\ntemperature with two different incident neutron wavelengths. The temperature\nand Q dependence of the measured scattering function suggests the presence of\nmagnon-phonon coupling in almost all branches. The present results are in\nagreement with the strong magnetoelastic effects observed previously.",
        "positive": "Strain-tuning Bloch- and N\u00e9el-type magnetic skyrmions: a phase-field\n  simulation: Strain manipulation of the magnetic domains, such as the stripe domains and\nskyrmions, has attracted considerable attention because of its potential\napplications for magnetic logic and memory devices. Here, utilizing phase-field\nmodeling, we demonstrate the deterministic modulation of the orientation and\nthe configuration of the stripe domains and skyrmions by using a uniaxial\nstrain. The reorientation of the stripe domains can be caused by a suitable\nstrain, and the direction of the reorientated domains is determined by the\ndirection of the applied uniaxial strain and the type of domain walls,\nincluding Bloch- and N\\'eel- types. Furthermore, by constructing a phase\ndiagram, we discovered that when the uniaxial tensile strain increases, the\nferromagnetic islands undergo a continuous phase transition from a skyrmion to\nmulti-domains or a single domain. The competition between magnetic anisotropy\nenergy and stray field energy leads to the continuous phase transition and the\nformation of domain patterns under the uniaxial tensile strain. Our research\nprovides a theoretical foundation for the development of strain-controlled\nmagnetic domain designs."
    },
    {
        "anchor": "Understanding Mechanical Characteristics of FeNiCrCoCu HEA in Nanoscale\n  Laser Powder Bed Fusion via Molecular Dynamics: The concept of alloying multiple principal elements at high concentrations\nhas led to the development of High Entropy Alloys (HEAs) with exceptional\nmechanical properties, making them the focus of major recent scientific\nendeavors. Geometrically complex HEAs with tailored microstructural\ncharacteristics can be produced using additive manufacturing technologies such\nas powder bed fusion (PBF). However, an in-depth study on the effect of process\nthermal conditions during PBF is required to effectively fabricate HEAs with\ndesirable mechanical characteristics. Thus, in our present molecular dynamic\n(MD) study we have explored the implication of PBF process thermal conditions\non the mechanical characteristics of FeNiCrCoCu HEA by systematically varying\nlaser scan speed from 0.4 {\\AA}/ps to 0.1 {\\AA}/ps, unidirectional and\nreversing laser passes from 1 to 4, and laser power from 100 microwatts to 220\nmicrowatts. Our investigation suggests that reducing the laser scanning speed\nup to a critical velocity of 0.2 {\\AA}/ps considerably improves mechanical\nstrengths, with further reduction creating severe surface defects. Decreased\nultimate tensile strength (UTS) is associated with the annihilation of the bulk\nsessile dislocations during tensile straining marking an early yield failure.\nAlternately, the material's strength could be improved by annealing with\nseveral unidirectional laser passes over the same target region, resulting in\nenhanced UTS due to subtler yield points. Increasing laser power aids in\nameliorating material density ultimately leading to higher UTS even in\nnon-dislocation-free structures. These findings will assist researchers to\nunderstand the underlying effects and optimize process thermal parameters to\nfabricate superior HEAs utilizing additive manufacturing.",
        "positive": "Controlled introduction of defects to delafossite metals by electron\n  irradiation: The delafossite metals PdCoO$_{2}$, PtCoO$_{2}$ and PdCrO$_{2}$ are among the\nhighest conductivity materials known, with low temperature mean free paths of\ntens of microns in the best as-grown single crystals. A key question is whether\nthese very low resistive scattering rates result from strongly suppressed\nbackscattering due to special features of the electronic structure, or are a\nconsequence of highly unusual levels of crystalline perfection. We report the\nresults of experiments in which high energy electron irradiation was used to\nintroduce point disorder to the Pd and Pt layers in which the conduction\noccurs. We obtain the cross-section for formation of Frenkel pairs in absolute\nunits, and cross-check our analysis with first principles calculations of the\nrelevant atomic displacement energies. We observe an increase of resistivity\nthat is linear in defect density with a slope consistent with scattering in the\nunitary limit. Our results enable us to deduce that the as-grown crystals\ncontain extremely low levels of in-plane defects of approximately $0.001\\%$.\nThis confirms that crystalline perfection is the most important factor in\nrealizing the long mean free paths, and highlights how unusual these\ndelafossite metals are in comparison with the vast majority of other\nmulti-component oxides and alloys. We discuss the implications of our findings\nfor future materials research."
    },
    {
        "anchor": "Large valley splitting in monolayer WS$_2$ by proximity coupling to an\n  insulating antiferromagnetic substrate: Lifting the valley degeneracy is an efficient way to achieve valley\npolarization for further valleytronics operations. In this work, we demonstrate\nthat a large valley splitting can be obtained in monolayer transition metal\ndichalcogenides by magnetic proximity coupling to an insulating\nantiferromagnetic substrate. As an example, we perform first-principles\ncalculations to investigate the electronic structures of monolayer WS$_2$ on\nthe MnO(111) surface. Our calculation results suggest that a large valley\nsplitting of 214 meV, which corresponds to a Zeeman magnetic field of 1516 T,\nis induced in the valence band of monolayer WS$_2$. The magnitude of valley\nsplitting relies on the strength of interfacial orbital hybridization, and can\nbe continually tuned by applying an external out-of-plane pressure and in-plane\nstrain. More interestingly, we find that both spin and valley index will flip\nwhen the magnetic ordering of MnO is reversed. Besides, owing to the sizeable\nBerry curvature and time-reversal symmetry breaking in the WS$_2$/MnO\nheterostructure, a spin and valley polarized anomalous Hall current can be\ngenerated in the presence of an in-plane electric field, which allow one to\ndetect valleys by the electrical approach. Our results shed light on the\nrealization of valleytronic devices using the antiferromagnetic insulator as\nthe substrate.",
        "positive": "Electrospun nanofibers of polyCD/PMAA polymers and their potential\n  application as drug delivery system: Herein, we used an electrospinning process to develop highly efficacious and\nhydrophobic coaxial nanofibers based on poly-cyclodextrin (polyCD) associated\nwith poly(methacrylic acid) (PMAA) that combines polymeric and supramolecular\nfeatures for modulating the release of the hydrophilic drug, propranolol\nhydrochloride (PROP). For this purpose, polyCD was synthesized and\ncharacterized, and its biocompatibility was assessed using fibroblast\ncytotoxicity tests. Moreover, the interactions between the guest PROP molecule\nand both polyCD and $\\beta$CD were found to be spontaneous. Subsequently, PROP\nwas encapsulated in uniaxial and coaxial polyCD/ PMAA nanofibers. A lower PROP\nburst effect (reduction of approximately 50%) and higher modulation were\nobserved from the coaxial than from the uniaxial fibers. Thus, the coaxial\nnanofibers could potentially be a useful strategy for developing a controlled\nrelease system for hydrophilic molecules."
    },
    {
        "anchor": "Liquid phase production of graphene by exfoliation of graphite in\n  surfactant/water solutions: We have demonstrated a method to disperse and exfoliate graphite to give\ngraphene suspended in water-surfactant solutions. Optical characterisation of\nthese suspensions allowed the partial optimisation of the dispersion process.\nTransmission electron microscopy showed the dispersed phase to consist of small\ngraphitic flakes. More than 40% of these flakes had <5 layers with ~3% of\nflakes consisting of monolayers. These flakes are stabilised against\nreaggregation by Coulomb repulsion due to the adsorbed surfactant. However, the\nlarger flakes tend to sediment out over ~6 weeks, leaving only small flakes\ndispersed. It is possible to form thin films by vacuum filtration of these\ndispersions. Raman and IR spectroscopic analysis of these films suggests the\nflakes to be largely free of defects and oxides. The deposited films are\nreasonably conductive and are semi-transparent. Further improvements may result\nin the development of cheap transparent conductors.",
        "positive": "Anomalous Magnetic and Thermal Behavior in Some RMn2O5 Oxides: The RMn2O5 (R=Pr, Nd, Sm, and Eu) oxides showing magnetoelectric (ME)\nbehavior have been prepared in polycrystalline form by a standard citrate\nroute. The lattice parameters, obtained from the powder XRD analysis, follow\nthe rare-earth contraction indicating the trivalent character of the R ions.\nCusp-like anomalies in the magnetic susceptibility curve and sharp peaks in the\nspecific heat were reported at the corresponding temperatures in RMn2O5 (R=Pr,\nNd, Sm, and Eu) indicating the magnetic or electric ordering transitions."
    },
    {
        "anchor": "Encounter-Limited Charge Carrier Recombination in Phase Separated\n  Organic Semiconductor Blends: The theoretical effects of phase separation on encounter-limited charge\ncarrier recombination in organic semiconductor blends are investigated using\nkinetic Monte Carlo (KMC) simulations of pump-probe experiments. Using model\nbulk heterojunction morphologies, the dependence of the recombination rate on\ndomain size and charge carrier mobility are quantified. Unifying competing\nmodels and simulation results, we show that the mobility dependence of the\nrecombination rate can be described using the power mean of the electron and\nhole mobilities with a domain size dependent exponent. Additionally, for domain\nsizes typical of organic photovoltaic devices, we find that phase separation\nreduces the recombination rate by less than one order of magnitude compared to\nthe Langevin model and that the mobility dependence can be approximated by the\ngeometric mean.",
        "positive": "Point defect evolution under irradiation: finite size effects and\n  spatio-temporal correlations: The evolution of point defect concentrations under irradiation is controlled\nby their diffusion properties, and by their formation and elimination\nmechanisms. The latter include the mutual recombination of vacancies and\ninterstitials, and the elimination of point defects at sinks. We show here that\nthe modelling of this evolution by means of atomistic kinetic Monte Carlo\n(AKMC) simulations, necessarily using small system sizes, introduces strong\nspace and time correlations between the vacancies and interstitials, which may\nstrongly affect the recombination rate and the point defect concentrations. In\nsuch situations, standard rate theory models fail to predict the actual point\ndefect concentrations. The effect is especially strong when the elimination of\npoint defects occurs only by recombination, but can still be significant in the\npresence of sinks. We propose a new Correlated Pair Theory that fully takes\ninto account the correlations between vacancy and interstitial pairs and\npredicts point defect concentrations in good agreement with AKMC simulations,\neven in very small systems. The Correlated Pair Theory can be used to modify\nthe elimination rates in AKMC simulations to yield point defect concentrations\nas predicted by the standard rate theory, i.e. representative of large systems,\neven when using small simulation boxes."
    },
    {
        "anchor": "A Helium-Surface Interaction Potential of Bi$_2$Te$_3$(111) from\n  Ultrahigh-Resolution Spin-Echo Measurements: We have determined an atom-surface interaction potential for the\nHe$-$Bi$_2$Te$_3$(111) system by analysing ultrahigh resolution measurements of\nselective adsorption resonances. The experimental measurements were obtained\nusing $^3$He spin-echo spectrometry. Following an initial free-particle model\nanalysis, we use elastic close-coupling calculations to obtain a\nthree-dimensional potential. The three-dimensional potential is then further\nrefined based on the experimental data set, giving rise to an optimised\npotential which fully reproduces the experimental data. Based on this analysis,\nthe He$-$Bi$_2$Te$_3$(111) interaction potential can be described by a\ncorrugated Morse potential with a well depth $D=(6.22\\pm0.05)~\\mathrm{meV}$, a\nstiffness $\\kappa =(0.92\\pm0.01)~\\mathrm{\\AA}^{-1}$ and a surface electronic\ncorrugation of $(9.6\\pm0.2)$% of the lattice constant. The improved\nuncertainties of the atom-surface interaction potential should also enable the\nuse in inelastic close-coupled calculations in order to eventually study the\ntemperature dependence and the line width of selective adsorption resonances.",
        "positive": "Why TiSe$_2$ is a band insulator: In its crystalline form, TiSe$_2$ is thought to be an insulator with a\nbandgap of ~0.1-0.2 eV. This materials system has attracted a much interest\nbecause of its rich array of unique properties. It forms a charge density wave\n(CDW) in both bulk and monolayer form, and there has been wide speculation that\nTiSe$_2$ is a rare realisation of an excitonic insulator. Using a\nself-consistent form of many body perturbation theory, we establish that\nTiSe$_2$ is a band insulator, but it is only nonmetallic as a consequence of\nfluctuations in nuclear positions about its nominally high-symmetry (P-3m1)\nphase. Below 200 K, TiSe$_2$ undergoes a transition to a charge density-wave\n(P-3c1) phase, which activates coupling between states near the Fermi level and\ncauses a gap to form. Above 200 K the nominal P-3m1 symmetry represents only a\ntime average of the true configuration. Dynamics in the nuclear configuration\nare responsible for TiSe$_2$ being nonmetallic. We demonstrate this through a\ncombination of molecular dynamics and the Self-consistent Quasiparticle\nApproximation. We further establish that ladder diagrams included in the\npolarizability (which includes the mechanism needed to form an excitonic\ninsulator) are of little importance."
    },
    {
        "anchor": "Shift of Fermi level by substitutional impurity-atom doping in diamond\n  and cubic- and hexagonal-boron nitrides: The density of states and the band diagrams were computed for diamond, cubic\nboron nitrde (cBN), and hexagonal boron nitride (hBN) using a\nKorringa-Kohn-Rostoker (KKR) scheme to investigate the shift of the Fermi level\nby impurity-atom doping below 10 at.%. The dopant atoms were B and N for\ndiamond, Be, Si, and C for cBN, and Be and C for hBN. It was found that the\nFermi level was located at the valence band maximum or the conduction band\nminimum in the following seven cases: (i) the B concentration was 0.3 at.% in\nB-doped diamond, (ii) the N concentration was 0.4 at.% in N-doped diamond,\n(iii) the concentration of Be substituting B was 0.9 at.% in cBN, (iv) the\nconcentration of Si substituting B was 0.3 at.% in cBN, (v) the concentration\nof C substituting B was 0.3 at.% in cBN, (vi) the concentration of C\nsubstituting N was 0.9 at.% in cBN, and (vii) the concentration of Be\nsubstituting B was ~2 at.% in hBN. Each of these values indicates the critical\ndopant concentration for semiconductor-to-metal transition. In B-doped diamond,\nit serves a measure for the occurrence of superconductivity at low temperature.",
        "positive": "Control and tunability of magnetic bubble states in multilayers with\n  strong perpendicular magnetic anisotropy at ambient conditions: The reversal of magnetic bubble helicity through topologically trivial\ntransient states provides an additional degree of freedom that promises the\ndevelopment of multidimensional magnetic memories. A key requirement for this\nconcept is the stabilization of bubble states at ambient conditions on\napplication-compatible substrates. In the present work we demonstrate a\nstabilization routine for remanent bubble states in high perpendicular magnetic\nanisotropy [(Co(0.44\\,nm)/Pt(0.7\\,nm)]$_X$, X = 48, 100, 150 multilayers on\nSi/SiO$_2$ substrates by exploring the effect of external magnetic fields\n($H_\\mathrm{m}$) of different strength and angles ($\\theta$) with respect to\nthe film surface normal. By systematic variation of these two parameters, we\ndemonstrate that remanent bubble density and mean bubble diameter can be\ncarefully tuned and optimized for each sample. Our protocol based on\nmagnetometry only reveals the densest remanent bubble states at $H_\\mathrm{m} =\n0.87 H_\\mathrm{s}$ ($H_\\mathrm{s}$ is the magnetic saturation field) and\n$\\theta=60^\\circ - 75^\\circ$ for all $X$ with a maximum of 3736 domains/100\n$\\mu$m$^2$ for the X = 48 sample. The experimental observations are supported\nby micromagnetic simulations taking into account the nanoscale lateral grain\nstructure of multilayers synthesized by magnetron sputter deposition, and thus\nhelping understand the different density of the bubble states found in these\nsystems."
    },
    {
        "anchor": "Spin and orbital magnetic moments of Fe in the $n$-type ferromagnetic\n  semiconductor (In,Fe)As: The electronic and magnetic properties of Fe atoms in the ferromagnetic\nsemiconductor (In,Fe)As codoped with Be have been studied by x-ray absorption\nspectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) at the Fe\n$L_{2,3}$ edge. The XAS and XMCD spectra showed simple spectral line shapes\nsimilar to Fe metal, but the ratio of the orbital and spin magnetic moments\n($M_\\mathrm{orb}$/$M_\\mathrm{spin}$) estimated using the XMCD sum rules was\nsignificantly larger than that of Fe metal, indicating a significant orbital\nmoment of Fe $3d$ electrons in (In,Fe)As:Be. The positive value of\n$M_\\mathrm{orb}$/$M_\\mathrm{spin}$ implies that the Fe $3d$ shell is more than\nhalf-filled, which arises from the hybridization of the Fe$^{3+}$ ($d^5$) state\nwith the charge-transfer $d^6\\underline{L}$ states, where $\\underline{L}$ is a\nligand hole in the host valence band. The XMCD intensity as a function of\nmagnetic field indicated hysteretic behavior of the superparamagnetic-like\ncomponent due to discrete ferromagnetic domains.",
        "positive": "A time-dependent density functional theory scheme for efficient\n  calculations of dynamic (hyper)polarizabilities: We present an efficient perturbative method to obtain both static and dynamic\npolarizabilities and hyperpolarizabilities of complex electronic systems. This\napproach is based on the solution of a frequency dependent Sternheimer\nequation, within the formalism of time-dependent density functional theory, and\nallows the calculation of the response both in resonance and out of resonance.\nFurthermore, the excellent scaling with the number of atoms opens the way to\nthe investigation of response properties of very large molecular systems. To\ndemonstrate the capabilities of this method, we implemented it in a real-space\n(basis-set free) code, and applied it to benchmark molecules, namely CO, H2O,\nand paranitroaniline (PNA). Our results are in agreement with experimental and\nprevious theoretical studies, and fully validate our approach."
    },
    {
        "anchor": "Anisotropic character of the metal-to-metal transition in\n  Pr4Ni$_3$O$_{10}$: As a member of the Ruddlesden-Popper Ln$_{n+1}$Ni$_n$O$_{3n+1}$ series\nrare-earth-nickelates, the Pr4Ni$_3$O$_{10}$ consists of infinite\nquasi-two-dimensional perovskite-like Ni-O based layers. Although a\nmetal-to-metal phase transition at Tpt = 157 K has been revealed by previous\nstudies, a comprehensive study of physical properties associated with this\ntransition has not yet been performed. We have grown single crystals of\nPr4Ni3O10 at high oxygen pressure, and report on the physical properties around\nthat phase transition, such as heat-capacity, electric-transport and\nmagnetization. We observe a distinctly anisotropic behavior between in-plane\nand out-of-plane properties: a metal-to-metal transition at Tpt within the a-b\nplane, and a metal-to-insulator-like transition along the c-axis with\ndecreasing temperature. Moreover, an anisotropic and anomalous negative\nmagneto-resistance is observed at Tpt that we attribute to a slight suppression\nof the first-order transition with magnetic field. The magnetic-susceptibility\ncan be well described by a Curie-Weiss law, with different Curie-constants and\nPauli-spin susceptibilities between the high-temperature and the\nlow-temperature phases. The single crystal X-ray diffraction measurements show\na shape variation of the different NiO6 octahedra from the high-temperature\nphase to the low-temperature phase. This subtle change of the environment of\nthe Ni sites is likely responsible for the different physical properties at\nhigh and low temperatures.",
        "positive": "Magnetocrystalline anisotropy and exchange probed by high-field\n  anomalous Hall effect in fully-compensated half-metallic Mn2RuxGa thin films: Magnetotransport is investigated in thin films of the half-metallic\nferrimagnet Mn$_2$Ru$_x$Ga in pulsed magnetic fields of up to 58 T. A\nnon-vanishing Hall signal is observed over a broad temperature range, spanning\nthe compensation temperature 155 K, where the net magnetic moment is strictly\nzero, the anomalous Hall conductivity is 6673 $\\Omega^{-1}.m^{-1}$ and the\ncoercivity exceeds 9 T. Molecular field modelling is used to determine the\nintra- and inter-sublattice exchange constants and from the spin-flop\ntransition we infer the anisotropy of the electrically active sublattice to be\n216 kJ/m$^3$ and predict the magnetic resonances frequencies. Exchange and\nanisotropy are comparable and hard-axis applied magnetic fields result in a\ntilting of the magnetic moments from their collinear ground state. Our analysis\nis applicable to collinear ferrimagnetic half-metal systems."
    },
    {
        "anchor": "Identifying dominant recombination mechanisms in perovskite solar cells\n  by measuring the transient ideality factor: The ideality factor determined by measuring the open circuit voltage (VOC) as\nfunction of light intensity is often used as a means to identify the dominant\nrecombination mechanism in solar cells. However, applying this Suns-VOC\ntechnique to perovskite cells is problematic since the VOC evolves with time in\na way which depends on the previously applied bias (Vpre), the light intensity,\nand the device architecture/processing. Here we show that the dominant\nrecombination mechanism in two structurally similar CH3NH3PbI3 devices\ncontaining either mesoporous Al2O3 or TiO2 layers can be identified from the\nsignature of the transient ideality factor following application of a forward\nbias, Vpre, to the device in the dark. The transient ideality factor, is\nmeasured by monitoring the temporal evolution of VOC at different light\nintensities. The initial values of the transient ideality were consistent with\ncorresponding photoluminescence vs intensity as well as electroluminescence vs\ncurrent density measurements. Time-dependent simulations of the measurement on\nmodelled devices, which include the effects of mobile ionic charge, show that\nShockley Read Hall (SRH) recombination through deep traps at the charge\ncollection interfaces is dominant in both devices. Using transient photovoltage\nmeasurements superimposed on the evolving VOC of bifacial devices we further\nshow that the charge collection interface extends throughout the mesoporous\nTiO2 layer, consistent with a transient ideality signature corresponding to SRH\nrecombination in the bulk of the film. This information could not be inferred\nfrom an ideality factor determined from only steady-state VOC values. The\nmethod we have developed will be useful for identifying performance bottlenecks\nin new variants of perovskite devices by comparison with the transient ideality\nsignatures we have predicted for a range of possible recombination schemes.",
        "positive": "Size-dependent lattice dynamics of atomically precise cadmium selenide\n  quantum dots: Material properties depend sensitively on the atomic arrangements and atomic\nbonding, but these are notoriously difficult to measure in nanosized atomic\nclusters due to the small size of the objects and the challenge of obtaining\nbulk samples of identical clusters. Here we have combined the recent ability to\nmake gram quantities of identical semiconductor quantum-dot nanoparticles with\nthe ability to measure lattice dynamics on small sample quantities of\nhydrogenated materials using high energy resolution inelastic x-ray scattering\n(HERIX), to measure the size-dependence of the phonon density of states (PDOS)\nin CdSe quantum dots. The fact that we have atomically precise structural\nmodels for these nanoparticles allows the calculation of the PDOS using Density\nFunctional Theory (DFT), providing both experimental and theoretical\nconfirmations of the important role that the inertia of the surface capping\nspecies plays on determining the lattice dynamics."
    },
    {
        "anchor": "Atomic scale model and electronic structure of\n  Cu$_2$O/CH$_3$NH$_3$PbI$_3$ interfaces in perovskite solar cells: Cuprous oxide has been conceived as a potential alternative to traditional\norganic hole transport layers in hybrid halide perovskite-based solar cells.\nDevice simulations predict record efficiencies using this semiconductor, but\nexperimental results do not yet show this trend. More detailed knowledge about\nthe Cu$_2$O/perovskite interface is mandatory to improve the photoconversion\nefficiency. Using density functional theory calculations, here we study the\ninterfaces of CH$_3$NH$_3$PbI$_3$ with Cu$_2$O to assess their influence on\ndevice performance. Several atomistic models of these interfaces are provided\nfor the first time, considering different compositions of the interface atomic\nplanes. The interface electronic properties are discussed on the basis of the\noptimal theoretical situation, but in connection with the experimental\nrealizations and device simulations. It is shown that the formation of\nvacancies in the Cu$_2$O terminating planes is essential to eliminate dangling\nbonds and trap states. The four interface models that fulfill this condition\npresent a band alignment favorable for photovoltaic conversion. Energy of\nadhesion, and charge transfer across the interfaces are also studied. The\ntermination of CH$_3$NH$_3$PbI$_3$ in PbI$_2$ atomic planes seems optimal to\nmaximize the photoconversion efficiency.",
        "positive": "First-principles investigation of magnetism and electronic structures of\n  substitutional $3d$ transition-metal impurities in bcc Fe: The magnetic and electronic structures of $3d$ impurity atoms from Sc to Zn\nin ferromagnetic body-centered cubic iron are investigated using the\nall-electron full-potential linearized augmented plane-wave method based on the\ngeneralized gradient approximation (GGA). We found that in general, the GGA\nresults are closer to the experimental values than those of the local spin\ndensity approximation. The calculated formation enthalpy data indicate the\nimportance of a systematic study on the ternary Fe-C-$X$ systems rather than\nthe binary Fe-$X$ systems, in steel design. The lattice parameters are\noptimized and the conditions for spin polarization at the impurity sites are\ndiscussed in terms of the local Stoner model. Our calculations, which are\nconsistent with previous work, imply that the local spin-polarizations at Sc,\nTi, V, Cu, and Zn are induced by the host Fe atoms. The early transition-metal\natoms couple antiferromagnetically, while the late transition-metal atoms\ncouple ferromagnetically, to the host Fe atoms. The calculated total\nmagnetization ($M$) of bcc Fe is reduced by impurity elements from Sc to Cr as\na result of the antiferromagnetic interaction, with the opposite effect for\nsolutes which couple ferromagnetically. The changes in $M$ are attributed to\nnearest neighbor interactions, mostly between the impurity and host atoms. The\natom averaged magnetic moment is shown to follow generally the well-known\nSlater-Pauling curve, but our results do not follow the linearity of the\nSlater-Pauling curve. We attribute this discrepancy to the weak ferromagnetic\nnature of bcc Fe. The calculated Fermi contact hyperfine fields follow the\ntrend of the local magnetic moments. The effect of spin-orbit coupling is found\nnot to be significant although it comes into prominence at locations far from\nthe impurity sites."
    },
    {
        "anchor": "Chirality-induced linear response properties in non-coplanar Mn$_3$Ge: Taking the non-collinear antiferromagnetic hexagonal Heusler compound\nMn$_3$Ge as a reference system, the contributions to linear response phenomena\narising solely from the chiral coplanar and non-coplanar spin configurations\nare investigated. Orbital moments, X-ray absorption, anomalous and spin Hall\neffects, as well as corresponding spin-orbit torques and Edelstein\npolarizations are studied depending on a continuous variation of the polar\nangle relative to the Kagome planes of corner-sharing triangles between the\nnon-collinear antiferromagnetic and the ferromagnetic limits. By scaling the\nspeed of light from the relativistic Dirac case to the non-relativistic limit\nthe chirality-induced or topological contributions can be identified by\nsuppressing the spin-orbit coupling.",
        "positive": "On the Dynamical Ferromagnetic, Quantum Hall, and Relativistic Effects\n  on the Carbon Nanotubes Nucleation and Growth Mechanism: The mechanism of carbon nanotube (CNT) nucleation and growth has been a\nmystery for over 15 years. Prior models have attempted the extension of older\nclassical transport mechanisms. In July 2000, a more detailed and accurate\nnonclassical, relativistic mechanism was formulated considering the detailed\ndynamics of the electronics of spin and orbital rehybridization between the\ncarbon and catalyst via novel mesoscopic phenomena and quantum dynamics.\nFerromagnetic carbon was demonstrated. Here, quantum (Hall) effects and\nrelativistic effects of intense many body spin-orbital interactions for novel\norbital rehybridization dynamics (Little Effect) are proposed in this new\ndynamical magnetic mechanism. This dynamic ferromagnetic mechanism is proven by\nimposing dynamic and static magnetic fields during CNT syntheses and observing\nthe different influence of these external magnetic environments on the\ncatalyzing spin currents and spin waves and the resulting CNT formation."
    },
    {
        "anchor": "Additive interfacial chiral interaction in multilayers for stabilization\n  of small individual skyrmion at room temperature: Facing the ever-growing demand for data storage will most probably require a\nnew paradigm. Nanoscale magnetic skyrmions are anticipated to solve this issue\nas they are arguably the smallest spin textures in magnetic thin films in\nnature. We designed cobalt-based multilayered thin films where the cobalt layer\nis sandwiched between two heavy metals providing additive interfacial\nDzyaloshinskii-Moriya interactions, which reach a value close to 2 mJ m-2 in\nthe case of the Ir|Co|Pt asymmetric multilayers. Using a\nmagnetization-sensitive scanning x-ray transmission microscopy technique, we\nimaged small magnetic domains at very low field in these multilayers. The study\nof their behavior in perpendicular magnetic field allows us to conclude that\nthey are actually magnetic skyrmions stabilized by the large\nDzyaloshinskii-Moriya interaction. This discovery of stable sub-100 nm\nindividual skyrmions at room temperature in a technologically relevant material\nopens the way for device applications in a near future.",
        "positive": "Electronic and optical properties of novel carbon allotropes: The phonon properties, electronic structures and optical properties of novel\ncarbon allotropes, such as monolayer penta-graphene (PG), double-layer PG and\nT12-carbon, were explored by means of first-principles calculations. Results of\nphonon calculations demonstrate that these exotic carbon allotropes are\ndynamically stable. In addition, the bulk T12 phase is an indirect-gap\nsemiconductor having a bandgap of ~4.89 eV. Whereas the bulk material\ntransforms to a 2D phase, the monolayer and double-layer PG become quasi-direct\ngap semiconductors with smaller band gaps of ~2.64 eV and ~3.27eV,\nrespectively. Furthermore, the partial charge density analysis indicates that\nthe 2D phases retain part of the electronic characteristics of the T12 phase.\nThe linear photon energy-dependent dielectric functions and related optical\nproperties including refractive index, extinction coefficient, absorption\nspectrum, reflectivity, and energy loss spectrum were also computed and\ndiscussed. The structural estimation obtained as well as other findings are in\nagreement with existing theoretical data. The calculated results are beneficial\nto the practical applications of these exotic carbon allotropes in\noptoelectronics and electronics."
    },
    {
        "anchor": "Precision Multi-Mode Dielectric Characterization of a Crystalline\n  Perovskite Enables Determination of the Temperature-Dependent Phase\n  Transitions: Simple perovskite crystals undergo structural phase transitions on cooling to\nlow temperatures, which significantly change the material properties of the\ncrystal. In this work we rigorously characterize the temperature evolution of\npermittivity of a perovskite crystal as it undergoes phase transitions. In\nparticular, we have undertaken precision measurements of a single crystal of\nStrontium Titanate from 294.6 K to 5.6 K, by measuring the frequency of\nmultiple microwave transverse electric and magnetic resonant modes\nsimultaneously. The multi-mode microwave measurement technique of resonant\nfrequency used in this work allows high precision determination of any induced\nanisotropy of the permittivity as the crystal undergoes structural phase\ntransitions. Compared with previous results we unequivocally show that the\npermittivity has an isotropic value of $316.3\\pm2.2$ at room temperature,\nconsistent with its well-known cubic structure, and determine the onset of\ndielectric anisotropy as the crystal is cooled to lower temperatures. We show\nthat the crystal exhibits uniaxial anisotropy in the permittivity below 105 K\nwhen the structure becomes tetragonal, and exhibits biaxial anisotropy in the\npermittivity below 51 K when the structure becomes orthorhombic.",
        "positive": "A simple TEM method for fast thickness characterization of suspended\n  graphene flakes: We present a simple and fast method for thickness characterization of\nsuspended graphene flakes that is based on transmission electron microscopy\n(TEM) techniques. For this method, the dynamical theory of electron diffraction\n(Bloch-wave approach in two-beam case approximation) was used to obtain an\nanalytical expression for the intensity of the transmitted electron beam I0(t),\nas function of the specimen thickness t for thin samples (t<< {\\lambda}; where\n{\\lambda} is the absorption constant for graphite). We show that in thin\ngraphite crystals the transmitted intensity is a linear function of the\nthickness. To obtain a more quantitative description of I0(t), high resolution\n(HR) TEM simulations are performed using the Bloch wave approach of the JEMS\nsoftware. From such calculations, we obtain {\\lambda} for a 001 zone axis\norientation, in a two-beam case and in a low symmetry orientation.\nSubsequently, HR (used to determine t) and bright-field (to measure I0(0) and\nI0(t)) images were acquired to experimentally determine {\\lambda}. We obtain\nthat the experimental value in the low symmetry orientation is close to the\ncalculated value (i.e. {\\lambda}=225 nm for 300 kV accelerating voltage and 3\nmrad collection angle). The simulations also show that the linear approximation\nobtained from the analytical expression is valid up to a sample thickness of\nseveral ten nanometers, depending on the orientation. When compared to standard\ntechniques for thickness determination of graphene/graphite, the method we\npropose has the advantage of being relatively simple and fast, requiring only\nthe acquisition of bright-field images."
    },
    {
        "anchor": "A microspectroscopic study of the electronic homogeneity of ordered and\n  disordered Sr2FeMoO6: Besides a drastic reduction in saturation magnetization of disordered\nSr2FeMoO6 compared to highly ordered samples, magnetizations as a function of\nthe temperature for different disordered samples may also show qualitatively\ndifferent behaviors. We investigate the origin of such diversity by performing\nspatially resolved photoemission spectroscopy on various disordered samples.\nOur results establish that extensive electronic inhomogeneity, arising most\nprobably from an underlying chemical inhomogeneity in disordered samples is\nresponsible for the observed magnetic inhomogeneity. It is further pointed out\nthat these inhomogeneities are connected with composition fluctuations of the\ntype Sr2Fe1+xMo1-xO6 with Fe-rich (x>0) and Mo-rich (x<0) regions.",
        "positive": "Mechanical characterization and failure modes in the peeling of\n  adhesively bonded strips from a plastic substrate: With the aim of understanding failure modes in the peeling of silicone-based\nadhesive joints and, in particular, the occurrence of adhesive or cohesive\nfailure, an experimental campaign has been conducted by considering plastic\nsubstrates with different surface roughness. A flexible strip has been bonded\nonto such substrates using a silicone adhesive, by controlling its thickness.\nPeeling tests with 90{\\deg} and 180{\\deg} peeling angle configurations have\nbeen performed and the effect of joint parameters, such as surface roughness\nand adhesive thickness, onto the adhesion energy and the failure mode are\nherein discussed in detail. Experimental results show that the failure mode\nvaries in each peeling test configuration such that in the case of 180{\\deg}\npeeling test there is mainly cohesive failure, while for 90{\\deg} peeling\nangle, a combination of adhesive and cohesive failure occurs. Moreover, due to\nthe presence of different failure modes in each peeling configuration, the\nsubstrate roughness can increase the adhesion energy only in 90{\\deg} peeling\ntests."
    },
    {
        "anchor": "High-Resolution X-Ray Studies of the Direct Spin Contact of EuO with\n  Silicon: Ferromagnetic semiconductor europium monoxide (EuO) is believed to be an\neffective spin injector when directly integrated with silicon. Injection\nthrough spin-selective ohmic contact requires superb structural quality of the\ninterface EuO/Si. Recent breakthrough in manufacturing free-of-buffer-layer\nEuO/Si junctions calls for structural studies of the interface between the\nsemiconductors. Ex situ high-resolution X-ray diffraction and reflectivity\naccompanied by in situ reflection high-energy electron diffraction reveal\ndirect coupling at the interface. A combined analysis of XRD and XRR data\nprovides a common structural model. The structural quality of the EuO/Si spin\ncontact by far exceeds that of previous reports and thus makes a step forward\nto the ultimate goals of spintronics.",
        "positive": "Splitting between Bright and Dark excitons in Transition Metal\n  Dichalcogenide Monolayers: The optical properties of transition metal dichalcogenide monolayers such as\nthe two-dimensional semiconductors MoS$_2$ and WSe$_2$ are dominated by\nexcitons, Coulomb bound electron-hole pairs. The light emission yield depends\non whether the electron-hole transitions are optically allowed (bright) or\nforbidden (dark). By solving the Bethe Salpeter Equation on top of $GW$ wave\nfunctions in density functional theory calculations, we determine the sign and\namplitude of the splitting between bright and dark exciton states. We evaluate\nthe influence of the spin-orbit coupling on the optical spectra and clearly\ndemonstrate the strong impact of the intra-valley Coulomb exchange term on the\ndark-bright exciton fine structure splitting."
    },
    {
        "anchor": "Are Mobilities in Hybrid Organic-Inorganic Halide Perovskites Actually\n  'High'?: We present an experimental and theoretical viewpoint on the electronic\ncarrier mobilities of typical hybrid organic-inorganic perovskites (HOIPs).\nWhile these mobilities are often quoted as high, a review of them shows that\nalthough otherwise the semiconducting properties of HOIPs are impressively\ngood, mobilities of HOIPs used in most solar cells are actually not that high.\nThis is especially apparent if they are compared to those of inorganic\nsemiconductors used in other high efficiency solar cells. We critically examine\npossible causes and focus on electron-lattice coupling mechanisms that are\nactive at room temperature, and can lead to carrier scattering. From this, we\npropose scattering due to acoustic phonons or polarons as possible causes, but\nalso point out the difficulties with each of these in view of additional\nexperimental and theoretical findings in the literature. Further research in\nthis direction will contribute to making HOIP solar cells even more efficient\nthan they already are.",
        "positive": "Temperature evolution of the band-gap in BiFeO3 traced by resonant Raman\n  scattering: Knowledge of the electronic band structure of multiferroic oxides, crucial\nfor the understanding and tuning of photo-induced effects, remains very limited\neven in the model and thoroughly studied BiFeO3. Here, we investigate the\nelectronic band structure of BiFeO3 using Raman scattering with twelve\ndifferent excitation wavelengths ranging from the blue to the near infrared. We\nshow that resonant Raman signatures can be assigned to direct and indirect\nelectronic transitions, as well as in-gap electronic levels, most likely\nassociated to oxygen vacancies. Their temperature evolution establishes that\nthe remarkable and intriguing variation of the optical band-gap can be related\nto the shrinking of an indirect electronic band-gap, while the energies for\ndirect electronic transitions remains nearly temperature independent."
    },
    {
        "anchor": "Aggregation of BiTe Monolayer on Bi$_2$Te$_3$(111) Induced by Diffusion\n  of Intercalated Atoms in van der Waals Gap: We report a post-growth aging mechanism of Bi$_2$Te$_3$(111) films with\nscanning tunneling microscopy in combination with density functional theory\ncalculation. It is found that a monolayered structure with a squared lattice\nsymmetry gradually aggregates from surface steps. Theoretical calculations\nindicate that the van der Waals (vdW) gap not only acts as a natural reservoir\nfor self-intercalated Bi and Te atoms, but also provides them easy diffusion\npathways. Once hopping out of the gap, these defective atoms prefer to develop\ninto a two dimensional BiTe superstructure on the Bi$_2$Te$_3$(111) surface\ndriven by positive energy gain. Considering the common nature of weakly bonding\nbetween vdW layers, we expect such unusual diffusion and aggregation of the\nintercalated atoms may be of general importance for most kinds of vdW layered\nmaterials.",
        "positive": "Prospects of high temperature ferromagnetism in (Ga,Mn)As semiconductors: We report on a comprehensive combined experimental and theoretical study of\nCurie temperature trends in (Ga,Mn)As ferromagnetic semiconductors. Broad\nagreement between theoretical expectations and measured data allows us to\nconclude that T_c in high-quality metallic samples increases linearly with the\nnumber of uncompensated local moments on Mn_Ga acceptors, with no sign of\nsaturation. Room temperature ferromagnetism is expected for a 10% concentration\nof these local moments. Our magnetotransport and magnetization data are\nconsistnent with the picture in which Mn impurities incorporated during growth\nat interstitial Mn_I positions act as double-donors and compensate neighboring\nMn_Ga local moments because of strong near-neighbor Mn_Ga-Mn_I\nantiferromagnetic coupling. These defects can be efficiently removed by\npost-growth annealing. Our analysis suggests that there is no fundamental\nobstacle to substitutional Mn_Ga doping in high-quality materials beyond our\ncurrent maximum level of 6.2%, although this achievement will require further\nadvances in growth condition control. Modest charge compensation does not limit\nthe maximum Curie temperature possible in ferromagnetic semiconductors based on\n(Ga,Mn)As."
    },
    {
        "anchor": "Multiscale modeling of plastic deformation of molybdenum and tungsten:\n  II. Yield criterion for single crystals based on atomistic studies of glide\n  of 1/2<111> screw dislocations: Based on the atomistic studies presented in Part I we develop analytical\nyield criteria for single crystals that capture the effect of shear stresses\nother than the Schmid stress (non-glide stresses) on the shear stress needed\nfor dislocation glide (Peierls stress). These yield criteria characterize a\nnon-associated plastic flow that originates owing to the complex response of\n1/2<111> screw dislocations to an applied stress tensor. Employing these\ncriteria we identify the operative slip systems for tensile/compressive loading\nalong various axes within the standard stereographic triangle and determine the\nensuing tension-compression asymmetry. This result is in an excellent\nqualitative agreement with available experimental data. Moreover, using the\nconstructed yield criteria within the Taylor homogenization procedure, we\ndemonstrate that effects associated with non-planar cores of screw dislocations\npersist in random polycrystals. This affects significantly critical phenomena\nsuch as shear localization, which is demonstrated by analyzing the cavitation\nin a ductile plastic solid.",
        "positive": "A density functional theory for symmetric radical cations from bonding\n  to dissociation: It is known for quite some time that approximate density functional (ADF)\ntheories fail disastrously when describing the dis-sociative symmetric radical\ncations R2+. Considering this dissociation limit, previous work has shown that\nHartree-Fock (HF) theory favors the R+1--R0 charge distribution while DF\napproximations favor the R+0.5 -- R+0.5. Yet, general quantum mechanical\nprinciples indicate that both these (as well as all intermediate) average\ncharge distributions are asymptotically energy degenerate. Thus HF and ADF\ntheories mistakenly break the symmetry but in a contradicting way. In this\nletter we show how to construct system-dependent long-range corrected (LC)\ndensity functionals that can successfully treat this class of molecules,\navoiding the spurious symmetry breaking. Examples and comparisons to\nexperimental data is given for R=H, He and Ne and it is shown that the new LC\ntheory improves considerably the theoretical description of the R2+ bond\nproperties, the long range form of the asymptotic potential curve as well as\nthe atomic polarizability. The broader impact of this finding is discussed as\nwell and it is argued that the widespread semi-empirical approach which\nadvocates treating the LC parameter as a system-independent parameter is in\nfact inappropriate under general circumstances."
    },
    {
        "anchor": "Tunable topological phases in nanographene-based spin-1/2\n  alternating-exchange Heisenberg chains: Unlocking the potential of topological order within many-body spin systems\nhas long been a central pursuit in the realm of quantum materials. Despite\nextensive efforts, the quest for a versatile platform enabling site-selective\nspin manipulation, essential for tuning and probing diverse topological phases,\nhas persisted. Here, we utilize on-surface synthesis to construct spin-1/2\nalternating-exchange Heisenberg (AH) chains[1] with antiferromagnetic couplings\n$J_1$ and $J_2$ by covalently linking Clar's goblets -- nanographenes each\nhosting two antiferromagnetically-coupled unpaired electrons[2]. Utilizing\nscanning tunneling microscopy, we exert atomic-scale control over the spin\nchain lengths, parities and exchange-coupling terminations, and probe their\nmagnetic response by means of inelastic tunneling spectroscopy. Our\ninvestigation confirms the gapped nature of bulk excitations in the chains,\nknown as triplons[3]. Besides, the triplon dispersion relation is successfully\nextracted from the spatial variation of tunneling spectral amplitudes.\nFurthermore, depending on the parity and termination of chains, we observe\nvarying numbers of in-gap $S=1/2$ edge spins, enabling the determination of the\ndegeneracy of distinct topological ground states in the thermodynamic\nlimit-either 1, 2, or 4. By monitoring interactions between these edge spins,\nwe identify the exponential decay of spin correlations. Our experimental\nfindings, corroborated by theoretical calculations, present a phase-controlled\nmany-body platform, opening promising avenues toward the development of\nspin-based quantum devices.",
        "positive": "Finite-Temperature Properties of Ba(Zr,Ti)O$_3$ Relaxors From First\n  Principles: A first-principles-based technique is developed to investigate properties of\nBa(Zr,Ti)O$_3$ relaxor ferroelectrics as a function of temperature. The use of\nthis scheme provides answers to important, unresolved and/or controversial\nquestions, such as: what do the different critical temperatures usually found\nin relaxors correspond to? Do polar nanoregions really exist in relaxors? If\nyes, do they only form inside chemically-ordered regions? Is it necessary that\nantiferroelectricity develops in order for the relaxor behavior to occur? Are\nrandom fields and random strains really the mechanisms responsible for relaxor\nbehavior? If not, what are these mechanisms? These {\\it ab-initio-based}\ncalculations also leads to a deep microscopic insight into relaxors."
    },
    {
        "anchor": "Predicting Core Electron Binding Energies in Elements of the First\n  Transition Series Using the $\u0394$-Self-Consistent-Field Method: The $\\Delta$-Self-Consistent-Field ($\\Delta$SCF) method has been established\nas an accurate and computationally efficient approach for calculating absolute\ncore electron binding energies for light elements up to chlorine, but\nrelatively little is known about the performance of this method for heavier\nelements. In this work, we present $\\Delta$SCF calculations of transition metal\n(TM) 2$p$ core electron binding energies for a series of 60 molecular compounds\ncontaining the first row transition metals Ti, V, Cr, Mn, Fe and Co. We find\nthat the calculated TM 2$p_{3/2}$ binding energies are less accurate than the\nresults for the lighter elements with a mean absolute error (MAE) of 0.73 eV\ncompared to experimental gas phase photoelectron spectroscopy results. However,\nour results suggest that the error depends mostly on the element and is rather\ninsensitive to the chemical environment. By applying an element-specific\ncorrection to the binding energies the MAE is reduced to 0.20 eV, similar to\nthe accuracy obtained for the lighter elements.",
        "positive": "Ab initio Investigation of Structural Stability and Exfoliation Energies\n  in Transition Metal Dichalcogenides based on Ti-, V-, and Mo-Group Elements: In this work, we report an ab initio investigation based on density\nfunctional theory of the structural, energetic and electronic properties of 2D\nlayered chalcogenides compounds based in the combination of the\ntransition-metals (Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and chalcogenides (S, Se,\nTe) in three polymorphic phases: trigonal prismatic (2H), octahedral (1T) and\ndistorted octahedral (1T$_{\\text{d}}$). We determined the most stable phases\nfor each compound, verifying the existence of the 1T$_{\\text{d}}$ phase for a\nsmall number of the compounds and we have also identified the magnetic\ncompounds. In addition, with the determination of the exfoliation energies, we\nindicated the potential candidates to form one layer material and we have also\nfound a relation between the exfoliation energy and the effective Bader charge\nin the metal, suggesting that when the materials present small exfoliation\nenergy, it is due to the Coulomb repulsion between the chalcogen planes.\nFinally, we analyzed the electronic properties, identifying the semiconductor,\nsemimetal and metal materials and predicting the band gap of the\nsemiconductors. In our results, the dependence of the band gap on the\n$d$-orbital is explicit. In conclusion, we have investigated the properties of\nstable and metastable phases for a large set of TMD materials, and our findings\nmay be auxiliary in the synthesis of metastable phases and in the development\nof new TMDs applications."
    },
    {
        "anchor": "Growth-Induced Strain in Chemical Vapor Deposited Monolayer MoS2:\n  Experimental and Theoretical Investigation: Monolayer molybdenum disulphide (MoS$_2$) is a promising two-dimensional (2D)\nmaterial for nanoelectronic and optoelectronic applications. The large-area\ngrowth of MoS$_2$ has been demonstrated using chemical vapor deposition (CVD)\nin a wide range of deposition temperatures from 600 {\\deg}C to 1000 {\\deg}C.\nHowever, a direct comparison of growth parameters and resulting material\nproperties has not been made so far. Here, we present a systematic experimental\nand theoretical investigation of optical properties of monolayer MoS$_2$ grown\nat different temperatures. Micro-Raman and photoluminescence (PL) studies\nreveal observable inhomogeneities in optical properties of the as-grown single\ncrystalline grains of MoS$_2$. Close examination of the Raman and PL features\nclearly indicate that growth-induced strain is the main source of distinct\noptical properties. We carry out density functional theory calculations to\ndescribe the interaction of growing MoS$_2$ layers with the growth substrate as\nthe origin of strain. Our work explains the variation of band gap energies of\nCVD-grown monolayer MoS$_2$, extracted using PL spectroscopy, as a function of\ndeposition temperature. The methodology has general applicability to model and\npredict the influence of growth conditions on strain in 2D materials.",
        "positive": "Mesoscale self-organization of polydisperse magnetic nanoparticles at\n  the water surface: In this study, we investigated the self-ordering process in Langmuir films of\npolydisperse iron oxide nanoparticles on a water surface, employing in-situ\nX-ray scattering, surface pressure-area isotherm analysis, and Brewster angle\nmicroscopy. X-ray reflectometry confirmed the formation of a monolayer, while\ngrazing incidence small-angle X-ray scattering revealed short-range lateral\ncorrelations with a characteristic length equal to the mean particle size.\nRemarkably, our findings indicated that at zero surface pressure, the particles\norganized into submicrometer clusters, merging upon compression to form a\nhomogeneous layer. These layers were subsequently transferred to a solid\nsubstrate using the Langmuir-Schaefer technique and further characterized via\nscanning electron microscopy and polarized neutron reflectometry. Notably, our\nmeasurements unveiled a second characteristic length in the lateral\ncorrelations, orders of magnitude longer than the mean particle diameter, with\npolydisperse particles forming circular clusters densely packed in a hexagonal\nlattice. Furthermore, our evidence suggested that the lattice constant of this\nmesocrystal depended on the characteristics of the particle size distribution,\nspecifically the mean particle size and the width of the size distribution.\nAdditionally, we observed internal size separation within these clusters, where\nlarger particles were positioned closer to the center of the cluster. Finally,\npolarized neutron reflectometry measurements provided valuable insights into\nthe magnetization profile across the layer."
    },
    {
        "anchor": "New two-dimensional phase of tin chalcogenides: candidates for\n  high-performance thermoelectric materials: Tin-chalcogenides SnX (X = Te, Se and S) have been arousing research interest\ndue to their thermoelectric physical properties. The two-dimensional (2D)\ncounterparts, which are expected to enhance the property, nevertheless, have\nnot been fully explored because of many possible structures. Generating\nvariable composition of 2D Sn$_{1-x}$X$_{x}$ systems (X = Te, Se and S) has\nbeen performed using global searching method based on evolutionary algorithm\ncombining with density functional calculations. A new hexagonal phase named by\n$\\beta'$-SnX is found by Universal Structure Predictor Evolutionary\nXtallography (USPEX), and the structural stability has been further checked by\nphonon dispersion calculation and the elasticity criteria. The $\\beta'$-SnTe is\nthe most stable among all possible 2D phases of SnTe including those\nexperimentally available phases. Further, $\\beta'$ phases of SnSe and SnS are\nalso found energetically close to the most stable phases. High thermoelectronic\n(TE) performance has been achieved in the $\\beta'$-SnX phases, which have\ndimensionless figure of merit (ZT) as high as $\\sim$0.96 to 3.81 for SnTe,\n$\\sim$0.93 to 2.51 for SnSe and $\\sim$1.19 to 3.18 for SnS at temperature\nranging from 300 K to 900 K with practically attainable carrier concentration\nof 5$\\times$10$^{12}$ cm$^{-2}$. The high TE performance is resulted from a\nhigh power factor which is attributed to the quantum confinement of 2D\nmaterials and the band convergence near Fermi level, as well as low thermal\nconductivity mainly from both low elastic constants due to weak inter-Sn\nbonding strength and strong lattice anharmonicity.",
        "positive": "Terahertz Metamaterials with Semiconductor Split-Ring Resonators for\n  Magnetostatic Tunability: We studied a metasurface constituted as a periodic array of semiconductor\nsplit-ring resonators. The resonance frequencies of the metasurface excited by\nnormally incident light were found to be continuously tunable in the terahertz\nregime through an external magnetostatic field of suitable orientation. As such\nmetasurfaces can be assembled into 3D metamaterials, the foregoing conclusion\nalso applies to metamaterials comprising semiconductor split-ring resonators."
    },
    {
        "anchor": "Magnon polaron formed by selectively coupled coherent magnon and phonon\n  modes of a surface patterned ferromagnet: Strong coupling between two quanta of different excitations leads to the\nformation of a hybridized state which paves a way for exploiting new degrees of\nfreedom to control phenomena with high efficiency and precision. A magnon\npolaron is the hybridized state of a phonon and a magnon, the elementary quanta\nof lattice vibrations and spin waves in a magnetically-ordered material. A\nmagnon polaron can be formed at the intersection of the magnon and phonon\ndispersions, where their frequencies coincide. The observation of magnon\npolarons in the time domain has remained extremely challenging because the weak\ninteraction of magnons and phonons and their short lifetimes jeopardize the\nstrong coupling required for the formation of a hybridized state. Here, we\novercome these limitations by spatial matching of magnons and phonons in a\nmetallic ferromagnet with a nanoscale periodic surface pattern. The spatial\noverlap of the selected phonon and magnon modes formed in the periodic\nferromagnetic structure results in a high coupling strength which, in\ncombination with their long lifetimes allows us to find clear evidence of an\noptically excited magnon polaron. We show that the symmetries of the localized\nmagnon and phonon states play a crucial role in the magnon polaron formation\nand its manifestation in the optically excited magnetic transients.",
        "positive": "Structural relaxation effects on interface and transport properties of\n  Fe/MgO(001) tunnel junctions: The interface structure of Fe/MgO(100) magnetic tunnel junctions predicted by\ndensity functional theory (DFT) depends significantly on the choice of exchange\nand correlation functional. Bader analysis reveals that structures obtained by\nrelaxing the cell with the local spin-density approximation (LSDA) display a\ndifferent charge transfer than those relaxed with the generalized gradient\napproximation (GGA). As a consequence, the electronic transport is found to be\nextremely sensitive to the interface structure. In particular, the conductance\nfor the LSDA-relaxed geometry is about one order of magnitude smaller than that\nof the GGA-relaxed one. The high sensitivity of the electronic current to the\ndetails of the interface might explain the discrepancy between the experimental\nand calculated values of magnetoresistance."
    },
    {
        "anchor": "Microwave magnetic excitations in U-type hexaferrite\n  Sr$_4$CoZnFe$_{36}$O$_{60}$ ceramics: Microwave (MW) spectra of ferrimagnetic U-hexaferrite\nSr$_4$CoZnFe$_{36}$O$_{60}$ ceramics were studied using several experimental\ntechniques from 100 MHz to 50 GHz at temperatures between 10 and 390 K. They\nrevealed 9 excitations, which exhibit remarkable temperature dependences near\nthe magnetic phase transitions at 145 K and 305 K. Some of them also change\nunder the application of a weak bias magnetic field at room temperature. Three\nlowest-frequency modes seen between 200 MHz and 3 GHz were assigned to the\ndynamics of the magnetic domains. The mode attributed to the natural\nferromagnetic resonance exhibits a dramatic critical slowing-down from 25 GHz\nat 390 K to 5 GHz near the 305 K phase transition, and again a hardening to ~11\nGHz on further cooling. The higher-frequency excitations are most likely spin\nwave (magnon) modes arising from the complex ferrimagnetic structure of\nSr$_4$CoZnFe$_{36}$O$_{60}$. The high sensitivity of the MW spectra to the weak\nmagnetic bias field $H$ < 700 Oe at room temperature is shown to be caused by\nthe transformation of the polydomain magnetic structure in randomly oriented\nceramic grains to a monodomain one. The MW response measured above 2 GHz using\ncoplanar and microstrip lines with different electromagnetic field distribution\nand sample coupling revealed the same excitations with similar temperature and\nbias field dependences. It confirms the reliability of the results and proves\nthe effectiveness of the used MW techniques.",
        "positive": "Geometry of Defects in Solids: The appealing connection between non-Euclidean geometries and defects in\nsolids is brought forth in this article. Drawing a correspondence between the\nnature of a defect and a specific geometric property of the material space not\nonly illuminates the underlying structure of defects in solids but also\nprovides an unambiguous way to represent defect densities within a physical\ntheory. We present a rigorous background of the relevant concepts from\nclassical differential geometry, as well as illustrations of isolated defects\nin a lattice, to motivate the relationship between continuous defect densities\nand various tensor fields in differential geometry. We identify the\nRiemann-Christoffel tensor (or curvature tensor), the Cartan tensor (or torsion\ntensor), and the nonmetricity tensor (obtained from the covariant derivative of\nthe metric tensor), associated with the material space, with the density of\ndisclinations, dislocations, and point-defects (vacancies, interstitials,\nsubstitutional), respectively. We end our discussion with remarks on the\nelastic stress field associated with defect distribution and on the analogy\nbetween the present theory and the general theory of relativity."
    },
    {
        "anchor": "Interfacial thermal conductance between TiO2 nanoparticle and water: A\n  molecular dynamics study: The interfacial thermal conductance (Kapitza conductance) between a TiO2\nnanoparticle and water is investigated using transient non-equilibrium\nmolecular dynamics. It is found that Kapitza conductance of TiO2 nanoparticles\nis one order of magnitude greater than other conventional nanoparticles such as\ngold, silver, silicon, platinum and also carbon nanotubes and graphene flakes.\nThis difference can be explained by comparing the contribution of electrostatic\ninteractions between the partially charged titanium and oxygen atoms and water\natoms to the van der Waals interactions, which increases the cooling time by\nabout 10 times. The effects of diameter and temperature of nanoparticle,\nsurface wettability on the interfacial thermal conductance are also\ninvestigated. The results showed that by increasing the diameter of the\nnanoparticle from 4 to 9 nm, Kapitza conductance decreased slightly. Also,\nincreasing the temperature of the heated nanoparticle from 400 K to 600 K led\nto thermal conductance enhancement. It has been found that increasing the\ncoupling strength of Lennard-Jones (LJ) potential from 0.5 to 4 caused the\nincrement of the Kapitza conductance about 20%. It is also shown that a\ncontinuum model which its input is provided by molecular dynamics can be a\nsuitable approximation to describe the thermal relaxation of a nanoparticle in\na liquid medium.",
        "positive": "Anharmonic Self-Energy of Phonons: Ab Initio Calculations and Neutron\n  Spin Echo Measurements: We have calculated (ab initio) and measured (by spin-echo techniques) the\nanharmonic self-energy of phonons at the X-point of the Brillouin zone for\nisotopically pure germanium. The real part agrees with former, less accurate,\nhigh temperature data obtained by inelastic neutron scattering on natural\ngermanium. For the imaginary part our results provide evidence that transverse\nacoustic phonons at the X-point are very long lived at low temperatures, i.e.\ntheir probability of decay approaches zero, as a consequence of an unusual\ndecay mechanism allowed by energy conservation."
    },
    {
        "anchor": "Magnetoelastic coupling in iron: Exchange interactions in {\\alpha}- and {\\gamma}-Fe are investigated within an\nab-initio spin spiral approach. We have performed total energy calculations for\ndifferent magnetic structures as a function of lattice distortions, related\nwith various cell volumes and the Bain tetragonal deformations. The effective\nexchange parameters in {\\gamma}-Fe are very sensitive to the lattice\ndistortions, leading to the ferromagnetic ground state for the tetragonal\ndeformation or increase of the volume cell. At the same time, the\nmagnetic-structure-independent part of the total energy changes very slowly\nwith the tetragonal deformations. The computational results demonstrate a\nstrong mutual dependence of crystal and magnetic structures in Fe and explain\nthe observable \"anti-Invar\" behavior of thermal expansion coefficient in\n{\\gamma}-Fe.",
        "positive": "Aluminum Oxide Layers as Possible Components for Layered Tunnel Barriers: We have studied transport properties of Nb/Al/AlOx/Nb tunnel junctions with\nultrathin aluminum oxide layers formed by (i) thermal oxidation and (ii) plasma\noxidation, before and after rapid thermal post-annealing of the completed\nstructures at temperatures up to 550 deg C. Post-annealing at temperatures\nabove 300 deg C results in a significant decrease of the tunneling conductance\nof thermally-grown barriers, while plasma-grown barriers start to change only\nat annealing temperatures above 450 deg C. Fitting the experimental I-V curves\nof the junctions using the results of the microscopic theory of direct\ntunneling shows that the annealing of thermally-grown oxides at temperatures\nabove 300 deg C results in a substantial increase of their average tunnel\nbarriers height, from ~1.8 eV to ~2.45 eV, versus the practically unchanged\nheight of ~2.0 eV for plasma-grown layers. This difference, together with high\nendurance of annealed barriers under electric stress (breakdown field above 10\nMV/cm) may enable all-AlOx and SiO2/AlOx layered \"crested\" barriers for\nadvanced floating-gate memory applications."
    },
    {
        "anchor": "Stabilization of Mn4+ in synthetic slags and identification of important\n  slag forming phases: The expected shortage of Li due to the strong increase in electromobility is\nan important issue for the recovery of Li from spent Li-ion batteries. One\napproach is pyrometallurgical processing, during which ignoble elements such as\nLi, Al and Mn enter the slag system. The Engineered Artificial Minerals (EnAM)\nstrategy aims to efficiently recover critical elements. This study focuses on\nstabilizing Li-manganates in a synthetic slag and investigates the relationship\nbetween Mn4+ and Mg and Al in relation to phase formation. Therefore, three\nsynthetic slags (Li, Mg, Al, Si, Ca, Mn, O) were synthesized. In addition to\nLiMn3+O2, Li2Mn4+O3 was also stabilized. Both phases crystallized in a\nCa-silicate-rich matrix. In the structure of Li2MnO3 and LiMnO2, Li and Mn can\nsubstitute each other in certain proportions. As long as a mix of Mn2+ and Mn3+\nis present in the slag, spinels form through the addition of Mg and/or Al.",
        "positive": "A micromechanics-based variational phase-field model for fracture in\n  geomaterials with brittle-tensile and compressive-ductile behavior: This paper presents a framework for modeling failure in quasi-brittle\ngeomaterials under different loading conditions. A micromechanics-based model\nis proposed in which the field variables are linked to physical mechanisms at\nthe microcrack level: damage is related to the growth of microcracks, while\nplasticity is related to the frictional sliding of closed microcracks.\nConsequently, the hardening/softening functions and parameters entering the\nfree energy follow from the definition of a single degradation function and the\nelastic material properties. The evolution of opening microcracks in tension\nleads to brittle behavior and mode I fracture, while the evolution of closed\nmicrocracks under frictional sliding in compression/shear leads to ductile\nbehavior and mode II fracture. Frictional sliding is endowed with a\nnon-associative law, a crucial aspect of the model that considers the effect of\ndilation and allows for realistic material responses with non-vanishing\nfrictional energy dissipation. Despite the non-associative law, a variationally\nconsistent formulation is presented using notions of energy balance and\nstability, following the energetic formulation for rate-independent systems.\nThe material response of the model is first described, followed by the\nnumerical implementation procedure and several benchmark finite element\nsimulations. The results highlight the ability of the model to describe\ntensile, shear, and mixed-mode fracture, as well as responses with\nbrittle-to-ductile transition. A key result is that, by virtue of the\nmicromechanical arguments, realistic failure modes can be captured, without\nresorting to the usual heuristic modifications considered in the phase-field\nliterature. The numerical results are thoroughly discussed with reference to\nprevious numerical studies, experimental evidence, and analytical fracture\ncriteria."
    },
    {
        "anchor": "Revised Periodic Boundary Conditions: Fundamentals, Electrostatics, and\n  the Tight-Binding Approximation: Many nanostructures today are low-dimensional and flimsy, and therefore get\neasily distorted. Distortion-induced symmetry-breaking makes conventional,\ntranslation-periodic simulations invalid, which has triggered developments for\nnew methods. Revised periodic boundary conditions (RPBC) is a simple method\nthat enables simulations of complex material distortions, either classically or\nquantum-mechanically. The mathematical details of this easy-to-implement\napproach, however, have not been discussed before. Therefore, in this paper we\nsummarize the underlying theory, present the practical details of RPBC,\nespecially related to a non-orthogonal tight-binding formulation, discuss\nselected features, electrostatics in particular, and suggest some examples of\nusage. We hope this article to give more insight to RPBC, to help and inspire\nnew software implementations capable of exploring the physics and chemistry of\ndistorted nanomaterials.",
        "positive": "The characterization of Co-nanoparticles supported on graphene: The results of density functional theory calculations and measurements using\nX-ray photoelectron spectroscopy of Co-nanoparticles dispersed on graphene/Cu\nare presented. It is found that for low cobalt thickness (0.02 nm - 0.06 nm)\nthe Co forms islands distributed non-homogeneously which are strongly oxidized\nunder exposure to air to form cobalt oxides. At greater thicknesses up to 2 nm\nthe upper Co-layers are similarly oxidized whereas the lower layers contacting\nthe graphene remain metallic. The measurements indicate a Co2+ oxidation state\nwith no evidence of a 3+ state appearing at any Co thickness, consistent with\nCoO and Co[OH]2. The results show that thicker Co (2nm) coverage induces the\nformation of a protective oxide layer while providing the magnetic properties\nof Co nanoparticles."
    },
    {
        "anchor": "Modulation of magnetization in BiFeO$_3$ using circularly polarized\n  light: BiFeO$_3$ is a multiferroic material featuring ferroelectricity and\nnoncollinear antiferromagnetism, the latter manifested as a cycloid of spin\ndensity. Definitive and efficient control of the characteristic spin texture of\nBiFeO$_3$ is attractive for emerging quantum devices. In this regard,\ncrystal-field $d\\rightarrow d$ excitations localized on Fe atomic sites in\nBiFeO$_3$ provide an avenue for manipulation of the spin texture as they induce\na complex interplay among the spin, charge, and lattice degrees of freedom. In\nthis work, the ab initio GW-BSE method is used to characterize these\nexcitations within an excitonic picture. We find that the $d-d$ transitions\nappear as strongly bound, chiral, spin-flip excitons deep within the electronic\nband gap as a result of the intricate competition between the lattice\npotential, the antiferromagnetic ordering, the spin-orbit coupling, and the\nelectron-hole interaction. Most crucially, these excitons are composed of\nelectron-hole pairs with opposite spins that constitute almost all of their\n$\\pm \\hbar$ total angular momentum. These excitons of specific angular momentum\ncan be selectively excited using circularly polarized light, consequently\nmodulating the local magnetic moment giving rise to transient ferrimagnetism.",
        "positive": "Photo-physical properties of He-related color centers in diamond: Diamond is a promising platform for the development of technological\napplications in quantum optics and photonics. The quest for color centers with\noptimal photo-physical properties has led in recent years to the search for\nnovel impurity-related defects in this material. Here, we report on a\nsystematic investigation of the photo-physical properties of two He-related\n(HR) emission lines at 535 nm and 560 nm created in three different diamond\nsubstrates upon implantation with 1.3 MeV He+ ions and subsequent annealing.\nThe spectral features of the HR centers were studied in an \"optical grade\"\ndiamond substrate as a function of several physical parameters, namely the\nmeasurement temperature, the excitation wavelength and the intensity of\nexternal electric fields. The emission lifetimes of the 535 nm and 560 nm lines\nwere also measured by means of time-gated photoluminescence measurements,\nyielding characteristic decay times of (29 +- 5) ns and (106 +- 10) ns,\nrespectively. The Stark shifting of the HR centers under the application of an\nexternal electrical field was observed in a CVD diamond film equipped with\nburied graphitic electrodes, suggesting a lack of inversion symmetry in the\ndefects' structure. Furthermore, the photoluminescence mapping under 405 nm\nexcitation of a \"detector grade\" diamond sample implanted at a 1x1010 cm-2 He+\nion fluence enabled to identify the spectral features of both the HR emission\nlines from the same localized optical spots. The reported results provide a\nfirst insight towards the understanding of the structure of He-related defects\nin diamond and their possible utilization in practical applications"
    },
    {
        "anchor": "Stability of ferroelectric bubble domains: Nanoscale ferroelectric topologies such as vortices, anti-vortices, bubble\npatterns etc. are stabilized in thin films by a delicate balance of both\nmechanical and electrical boundary conditions. A systematic understanding of\nthe phase stability of bubble domains, particularly when the above factors act\nsimultaneously, remains elusive. Here we present first-principle-based\nsimulations in combination with scanning probe microscopy of ultrathin\nepitaxial (001) PbZr0.4Ti0.6O3 heterostructures to address this gap. The\nsimulations predict that as-grown labyrinthine domains will transform to\nbubbles under combinations of reduced film thickness, increased mechanical\npressure and/or improved electrical screening. These topological transitions\nare explained by a common fundamental mechanism. Namely, we argue that,\nindependently of the nature of the driving force, the evolution of the domain\nmorphology allows the system to conserve its original residual depolarization\nfield. Thereby, the latter remains pinned to a value determined by an external\nor built-in electric bias. To verify our predictions, we then exploit\ntomographic atomic force microscopy to achieve the concurrent effect of\nreducing film thickness and increased mechanical stimulus. The results provide\na systematic understanding of phase stability and demonstrate controlled\nmanipulation of nanoscale ferroelectric bubble domains.",
        "positive": "Shell Model of BaTiO3 Derived from Ab-initio Total Energy Calculations: A shell model for ferroelectric perovskites fitted to results of\nfirst-principles density functional theory (DFT) calculations is strongly\naffected by approximations made in the exchange-correlation functional within\nDFT, and in general not as accurate as a shell model derived from experimental\ndata. We have developed an isotropic shell model for BaTiO3 based on the PBEsol\nexchange-correlation functional, which was specifically designed for crystal\nproperties of solids. Our shell model for BaTiO3 agrees with groundstate DFT\nproperties and the experimental lattice constants at finite temperatures. The\nsequence of phases of BaTiO3 (rhombohedral, orthorhombic, tetragonal, cubic) is\ncorrectly reproduced but the temperature scale of the phase transitions is\ncompressed. The temperature scale can be improved by scaling of the ab-initio\nenergy surface."
    },
    {
        "anchor": "Machine-learning-enhanced time-of-flight mass spectrometry analysis: Mass spectrometry is a widespread approach to work out what are the\nconstituents of a material. Atoms and molecules are removed from the material\nand collected, and subsequently, a critical step is to infer their correct\nidentities based from patterns formed in their mass-to-charge ratios and\nrelative isotopic abundances. However, this identification step still mainly\nrelies on individual user's expertise, making its standardization challenging,\nand hindering efficient data processing. Here, we introduce an approach that\nleverages modern machine learning technique to identify peak patterns in\ntime-of-flight mass spectra within microseconds, outperforming human users\nwithout loss of accuracy. Our approach is cross-validated on mass spectra\ngenerated from different time-of-flight mass spectrometry(ToF-MS) techniques,\noffering the ToF-MS community an open-source, intelligent mass spectra\nanalysis.",
        "positive": "A New Spin Gapless Semiconductors Family: Quaternary Heusler Compounds: Using first-principles calculations, we investigate the band structures of a\nseries of quaternary LiMgPdSn-type Heusler compounds. Our calculation results\nshow that five compounds CoFeMnSi, CoFeCrAl, CoMnCrSi, CoFeVSi and FeMnCrSb\npossess unique electronic structures characterized by a half-metallic gap in\none spin direction while a zero-width gap in the other spin direction showing\nspin gapless semiconducting behavior. We further analysis the electronic and\nmagnetic properties of all quaternary Heusler alloys involved, and reveal a\nsemi-empirical general rule (total valence electrons number being 26 or 28) for\nindentifying spin gapless semiconductors in Heusler compounds. The influences\nof lattice distortion and main-group element change have also been discussed."
    },
    {
        "anchor": "Calculating Quantum Transports Using Periodic Boundary Conditions: An efficient new method is presented to calculate the quantum transports\nusing periodic boundary conditions. This new method is based on a method we\ndeveloped previously, but with an essential change in solving the Schrodinger's\nequation. As a result of this change, the scattering states can be solved at\nany given energy. Compared to the previous method, the current method is faster\nand numerically more stable. The total computational time of the current method\nis similar to a conventional ground state calculation. Details of the procedure\nis presented in the current paper.",
        "positive": "A new look at the temperature-dependent properties of the\n  antiferroelectric model PbZrO3: an effective Hamiltonian study: A novel atomistic effective Hamiltonian scheme, incorporating an original and\nsimple bilinear energetic coupling, is developed and used to investigate the\ntemperature dependent physical properties of the prototype antiferroelectric\nPbZrO3 (PZO) system. This scheme reproduces very well the known experimental\nhallmarks of the complex Pbam orthorhombic phase at low temperatures and the\ncubic paraelectric state of Pm 3m symmetry at high temperatures. Unexpectedly,\nit further predicts a novel intermediate state also of Pbam symmetry, but in\nwhich anti-phase oxygen octahedral tiltings have vanished with respect to the\nPbam ground state. Interestingly, such new state exhibits a large dielectric\nresponse and thermal expansion that remarkably agree with previous experimental\nobservations and the x-ray experiments we performed. We also conducted direct\nfirst-principles calculations at 0K which further support such low energy\nphase. Within this fresh framework, a re-examination of the properties of PZO\nis thus called for."
    },
    {
        "anchor": "Spectral dynamics of topological shift-current in ferroelectric\n  semiconductor SbSI: Photoexcitation in solids brings about transitions of electrons/holes between\ndifferent electronic bands. If the solid lacks an inversion symmetry, these\nelectronic transitions support spontaneous photocurrent due to the topological\ncharacter of the constituting electronic bands; the Berry connection. This\nphotocurrent, termed shift current, is expected to emerge on the time-scale of\nprimary photoexcitation process. We observed ultrafast time evolution of the\nshift current in a prototypical ferroelectric semiconductor by detecting\nemitted terahertz electromagnetic waves. By sweeping the excitation photon\nenergy across the band gap, ultrafast electron dynamics as a source of\nterahertz emission abruptly changes its nature, reflecting a contribution of\nBerry connection upon interband optical transition. The shift excitation\ncarries a net charge flow, and is followed by a swing-over of the electron\ncloud on the sub-picosecond time-scale of electron-phonon interaction.\nUnderstanding these substantive characters of the shift current will pave the\nway for its application to ultrafast sensors and solar cells.",
        "positive": "Solid-State Effects on the Optical Excitation of Push-Pull Molecular\n  J-Aggregates by First-Principles Simulations: J-aggregates are a class of low-dimensional molecular crystals which display\nenhanced interaction with light. These systems show interesting optical\nproperties as an intense and narrow red-shifted absorption peak (J-band) with\nrespect to the spectrum of the corresponding monomer. The need to theoretically\ninvestigate optical excitations in J-aggregates is twofold: a thorough\nfirst-principles description is still missing and a renewed interest is rising\nrecently in understanding the nature of the J-band, in particular regarding the\ncollective mechanisms involved in its formation. In this work, we investigate\nthe electronic and optical properties of a J-aggregate molecular crystal made\nof ordered arrangements of organic push-pull chromophores. By using a time\ndependent density functional theory approach, we assess the role of the\nmolecular packing in the enhancement and red shift of the J-band along with the\neffects of confinement in the optical absorption, when moving from bulk to\nlow-dimensional crystal structures. We simulate the optical absorption of\ndifferent configurations (i.e., monomer, dimers, a polymer chain, and a\nmonolayer sheet) extracted from the bulk crystal. By analyzing the induced\ncharge density associated with the J-band, we conclude that it is a\nlongitudinal excitation, delocalized along parallel linear chains and that its\noverall red shift results from competing coupling mechanisms, some giving red\nshift and others giving blue shift, which derive from both coupling between\ntransition densities and renormalization of the single-particle energy levels."
    },
    {
        "anchor": "InN/In nanocomposites: Plasmonic effects and a hidden optical gap: InN/In nanocomposites with periodical In inclusions amounting up to 30% of\nthe total volume exhibit bright emission near 0.7 eV explicitly associated with\nIn clusters. Its energy and intensity depend on the In amount. The principal\nabsorption edge in the semiconductor host, as given by a photovoltaic response,\nis markedly higher than the onset of thermally detected absorption. These\nfindings, being strongly suggestive of plasmon-dominated emission and\nabsorption, are discussed in terms of electromagnetic enhancement taking into\naccount the In parallel-band transitions.",
        "positive": "Unambiguous symmetry assignment for the top valence band of ZnO by\n  magneto-optical studies of the free A-exciton state: We studied the circular polarization and angular dependences of the\nmagneto-photoluminescence spectra of the free A-exciton 1S state in wurtzite\nZnO at T = 5 K. The circular polarization properties of the spectra clearly\nindicate that the top valence band has Gamma_7 symmetry. The out-of-plane\ncomponent of the magnetic field, which is parallel to the sample's c axis,\nleads to linear Zeeman splitting of both the dipole-allowed Gamma_5 exciton\nstate and the weakly allowed Gamma_1/Gamma_2 exciton states. The in-plane\nfield, which is perpendicular to the c axis, increases the oscillator strength\nof the weak Gamma_1/Gamma_2 states by forming a mixed exciton state."
    },
    {
        "anchor": "Tunneling anisotropic magnetoresistance driven by resonant surface\n  states: First-principles calculations of Fe(001) surface: Fully-relativistic first-principles calculations of the Fe(001) surface\ndemonstrate that resonant surface (interface) states may produce sizeable\ntunneling anisotropic magnetoresistance in magnetic tunnel junctions with a\nsingle magnetic electrode. The effect is driven by the spin-orbit coupling. It\nshifts the resonant surface band via the Rashba effect when the magnetization\ndirection changes. We find that spin-flip scattering at the interface is\ncontrolled not only by the strength of the spin-orbit coupling, but depends\nstrongly on the intrinsic width of the resonant surface states.",
        "positive": "Vibrational stability of graphene under combined shear and axial strains: We study the vibrational properties of graphene under combined shear and\nuniaxial tensile strain using density-functional perturbation theory. Shear\nstrain always causes rippling instabilities with strain-dependent direction and\nwavelength; armchair strain contrasts this instability, enabling graphene\nstability in a large range of combined strains. A complementary description\nbased on membrane elasticity theory nicely clarifies the competition of\nshear-induced instability and uniaxial tension. We also report the large\nstrain-induced shifts of the split components of the G optical phonon line,\nwhich may serve as a shear diagnostic. As to the electronic properties, we find\nthat conical intersections move away from the Brillouin zone border under\nstrain, and they tend to coalesce at large strains, making the opening of gaps\ndifficult to assess. By a detailed search, we find that even at large strains,\nonly small gaps in the tens-of-meV range open at the former Dirac points."
    },
    {
        "anchor": "Effect of isotope disorder on the Raman spectra of cubic boron arsenide: Boron arsenide (c-BAs) is at the forefront of research on ultrahigh thermal\nconductivity materials. We present a Raman scattering study of isotopically\ntailored cubic boron arsenide single crystals for 11 isotopic compositions\nspanning the range from nearly pure c-$^{10}$BAs to nearly pure c-$^{11}$BAs.\nOur results provide insights on the effects of strong mass disorder on optical\nphonons and the appearance of two-mode behavior in the Raman spectra of mixed\ncrystals. Strong isotope disorder also relaxes the one-phonon Raman selection\nrules, resulting in disorder-activated Raman scattering by acoustic phonons.",
        "positive": "Easy axis orientation of Strontium ferrite thin films described by spin\n  reorientation: In plane orientation of magnetic easy axis of sputtered strontium hexaferrite\nthin films has been explained using classical Heisenberg Hamiltonian. The\nvariation of average value of in plane spin component with temperature was\nplotted in order to determine the temperature at which easy axis is oriented in\nthe plane of the strontium ferrite film. The average value of in plane spin\ncomponent in this 2-D model reaches zero at one particular temperature. This\nparticular temperature obtained using our theoretical model agrees with the\nexperimental value of the temperature of rf sputtered polycrystalline strontium\nferrite thin films deposited on polycrystalline Al2O3 substrates (500 0C). This\nspin reorientation temperature solely depends on the values of energy\nparameters used in our modified Heisenberg Hamiltonian equation."
    },
    {
        "anchor": "Anisotropic Etching and Nanoribbon Formation in Single-Layer Graphene: We demonstrate anisotropic etching of single-layer graphene by\nthermally-activated nickel nanoparticles. Using this technique, we obtain\nsub-10nm nanoribbons and other graphene nanostructures with edges aligned along\na single crystallographic direction. We observe a new catalytic channeling\nbehavior, whereby etched cuts do not intersect, resulting in continuously\nconnected geometries. Raman spectroscopy and electronic measurements show that\nthe quality of the graphene is resilient under the etching conditions,\nindicating that this method may serve as a powerful technique to produce\ngraphene nanocircuits with well-defined crystallographic edges.",
        "positive": "Strain-driven elastic and orbital-ordering effects on\n  thickness-dependent properties of manganite thin films: We report on the structural and magnetic characterization of (110) and (001)\nLa2/3Ca1/3MnO3 (LCMO) epitaxial thin films simultaneously grown on (110) and\n(001)SrTiO3 substrates, with thicknesses t varying between 8 nm and 150 nm. It\nis found that while the in-plane interplanar distances of the (001) films are\nstrongly clamped to those of the substrate and the films remain strained up to\nwell above t=100 nm, the (110) films relax much earlier. Accurate determination\nof the in-plane and out-of-plane interplanar distances has allowed concluding\nthat in all cases the unit cell volume of the manganite reduces gradually when\nincreasing thickness, approaching the bulk value. It is observed that the\nmagnetic properties (Curie temperature and saturation magnetization) of the\n(110) films are significantly improved compared to those of (001) films. These\nobservations, combined with 55Mn-nuclear magnetic resonance data and X-ray\nphotoemission spectroscopy, signal that the depression of the magnetic\nproperties of the more strained (001)LCMO films is not caused by an elastic\ndeformation of the perovskite lattice but rather due to the electronic and\nchemical phase separation caused by the substrate-induced strain. On the\ncontrary, the thickness dependence of the magnetic properties of the less\nstrained (110)LCMO films are simply described by the elastic deformation of the\nmanganite lattice. We will argue that the different behavior of (001) and\n(110)LCMO films is a consequence of the dissimilar electronic structure of\nthese interfaces."
    },
    {
        "anchor": "Crystal Nucleation in an AlNiZr Metallic Liquid: Within and Beyond\n  Classical Nucleation Theory: The Classical Nucleation Theory (CNT) has played a key role in crystal\nnucleation studies since the 19th century and has significantly advanced the\nunderstanding of nucleation. However, certain key assumptions of CNT, such as a\ncompact and spherical nucleating cluster and the concept of individual\ndiffusive jumps are questionable. The results of molecular dynamics (MD)\nstudies of crystal nucleation in a Al20Ni60Zr20 metallic liquid demonstrate\nthat the nucleating cluster is neither spherical nor compact. The seeding\nmethod was employed to determine the critical cluster size and nucleation\nparameters from CNT, which were then compared to those derived from the Mean\nFirst Passage Time (MFPT) method. While the CNT-based nucleation rate aligns\nwell with experimental data from similar metallic liquids, the MFPT rate\ndiffers significantly. Further, contrary to the assumption of individual jumps\nfor atoms to join the nucleating cluster, a cooperative mechanism of attachment\nor detachment is observed. This is accompanied by synchronized changes in the\nlocal potential energy. Similar cooperative motion also appeared in a\nnon-classical nucleation process, particularly during the coalescence of\nnuclei.",
        "positive": "Electronic and optical properties of ternary kagome\n  Rb$_{2}$Ni$_{3}$S$_4$: The application of semiconductors with optical properties has grown\nsignificantly in the development of semiconductor photovoltaics. In this study,\nthe electronic and optical properties of ternary transition metal sulfide\nRb$_{2}$Ni$_{3}$S$_4$ is studied by means of density functional theory\ncalculation within the framework of generalized gradient approximation. From\nthe structural perspective, Ni atoms is found to form a kagome-like lattice in\na two-dimensional plane of Rb$_{2}$Ni$_{3}$S$_4$. From the electronic structure\ncalculations, the material is found to be a semiconductor with an indirect band\ngap of $\\sim$0.67 eV. The orbital contributions to the density of states and\nband structure around the Fermi level are from the Ni-$3d$ and S-$3p$ states.\nSignificant hybridization was observed between the S-$3p_x$ and S-$3p_y$ with\nthe Ni-3$d_{xz}$ and Ni-3$d_{yz}$ orbitals. Interestingly, flat band was\nnoticed below the Fermi level demonstrating one significant feature of kagome\nlattice. From the optical calculations, Rb$_{2}$Ni$_{3}$S$_4$ is found to\nexhibit optical activity in both the visible and ultraviolet regions of the\nincident photon energies. This optical response suggests that the material as a\npotential candidate for opto-electronic device application, given its ability\nto interact with light across a broad range of wavelengths. This work is\nexpected to motivate experimental group for transport measurements and may\nprovide a new foundation for the development of opto-electronic applications."
    },
    {
        "anchor": "Z3 Charge Density Wave of Silicon Atomic Chains on a Vicinal Silicon\n  Surface: An ideal one-dimensional electronic system is formed along atomic chains on\nAu-decorated vicinal silicon surfaces but the nature of its low temperature\nphases has been puzzled for last two decades. Here, we unambiguously identify\nthe low temperature structural distortion of this surface using high resolution\natomic force microscopy and scanning tunneling microscopy. The most important\nstructural ingredient of this surface, the step-edge Si chains are found to be\nstrongly buckled, every third atoms down, forming trimer unitcells. This\nobservation is consistent with the recent model of rehybridized dangling bonds\nand rules out the antiferromagnetic spin ordering proposed earlier. The\nspectroscopy and electronic structure calculation indicate a charge density\nwave insulator with a Z3 topology making it possible to exploit topological\nphases and excitations. Tunneling current was found to substantially lower the\nenergy barrier between three degenerate CDW states, which induces a dynamically\nfluctuating CDW at very low temperature.",
        "positive": "Real-space characterization of reactivity towards water at Bi2Te3(111)\n  surface: Surface reactivity is important in modifying the physical and chemical\nproperties of surface sensitive materials, such as the topological insulators\n(TIs). Even though many studies addressing the reactivity of TIs towards\nexternal gases have been reported, it is still under heavy debate whether and\nhow the topological insulators react with H$_2$O. Here, we employ scanning\ntunneling microscopy (STM) to directly probe the surface reaction of\nBi$_2$Te$_3$ towards H$_2$O. Surprisingly, it is found that only the top\nquintuple layer is reactive to H$_2$O, resulting in a hydrated Bi bilayer as\nwell as some Bi islands, which passivate the surface and prevent from the\nsubsequent reaction. A reaction mechanism is proposed with H$_2$Te and hydrated\nBi as the products. Unexpectedly, our study indicates the reaction with water\nis intrinsic and not dependent on any surface defects. Since water inevitably\nexists, these findings provide key information when considering the reactions\nof Bi$_2$Te$_3$ with residual gases or atmosphere."
    },
    {
        "anchor": "Ab initio density functional theory study of uranium solubility in\n  Gd2Zr2O7 pyrochlore: In this study, an ab initio calculation is performed to investigate the\nuranium solubility in different sites of Gd2Zr2O7 pyrochlore. The Gd2Zr2O7\nmaintains its pyrochlore structure at low uranium dopant levels, and the\nlattice constants of Gd2(Zr2-yUy)O7 and (Gd2-yUy)Zr2O7 are generally expressed\nas being linearly related to the uranium content y. Uranium is found to be a\npreferable substitute for the B-site gadolinium atoms in cation-disordered\nGd2Zr2O7 (where gadolinium and zirconium atoms are swapped) over the A-site\ngadolinium atoms in ordered Gd2Zr2O7 due to the lower total energy of\n(Gd2-yZry)(Zr2-yUy)O7. The theoretical findings present a reasonable\nexplanation of recent experiment results.",
        "positive": "Method for Transferring High-Mobility CVD-Grown Graphene with\n  Perfluoropolymers: The transfer of graphene grown by chemical vapor deposition (CVD) using\namorphous polymers represents a widely implemented method for graphene-based\nelectronic device fabrication. However, the most commonly used polymer,\npoly(methyl methacrylate) (PMMA), leaves a residue on the graphene that limits\nthe mobility. Here we report a method for graphene transfer and patterning that\nemploys a perfluoropolymer---Hyflon---as a transfer handle and to protect\ngraphene against contamination from photoresists or other polymers. CVD-grown\ngraphene transferred this way onto LaAlO$_3$/SrTiO$_3$ heterostructures is\natomically clean, with high mobility (~30,000 cm$^2$V$^{-1}$s$^{-1}$) near the\nDirac point at 2 K and clear, quantized Hall and magneto-resistance. Local\ncontrol of the LaAlO$_3$/SrTiO$_3$ interfacial metal-insulator\ntransition---through the graphene---is preserved with this transfer method. The\nuse of perfluoropolymers such as Hyflon with CVD-grown graphene and other 2D\nmaterials can readily be implemented with other polymers or photoresists."
    },
    {
        "anchor": "In-plane Antiferromagnetism in Ferromagnetic Kagome Semimetal Co3Sn2S2: Co3Sn2S2 has been reported to be a Weyl semimetal with broken time-reversal\nsymmetry with c axis ferromagnetism (FM) below a Curie temperature of 177 K.\nDespite the large interest in Co3Sn2S2, the magnetic structure is still under\ndebate and recent studies have challenged our understanding of the magnetic\nphase diagram of Co3Sn2S2 by reporting unusual magnetic phases including the\npresence of exchange bias. Understanding the magnetism of Co3Sn2S2 is important\nsince its electronic band structure including the much-celebrated flat bands\nand Weyl nodes depend on the magnetic phase. In this work, using X-ray Magnetic\nCircular Dichroism (XMCD), we establish that the magnetic moment in Co arises\nfrom the spin, with negligible orbital moment. In addition, we detect an\nin-plane AFM minority phase in the sea of a FM phase using spatially-resolved\nangle-resolved photoemission spectroscopy ({\\mu}-ARPES) combined with density\nfunctional theory (DFT) calculation. Separately, we detect a sharp flat band\nprecisely at the Fermi level (EF) at some regions in the sample, which we\nattribute to a surface state. The AFM phase survives even to the low\ntemperature of 6 K. This example of entirely different magnetic ground states\nin a stoichiometric intermetallic invites further efforts to explore the\nobserved AFM phase and understand the origin and nature of the magnetic and\nelectronic inhomogeneity on the mesoscale and the interface between the AFM and\nFM phases.",
        "positive": "Effect of intense x-ray free-electron laser transient gratings on the\n  magnetic domain structure of Tm:YIG: Magnetic patterns can be controlled globally using fields or spin polarized\ncurrents. In contrast, the local control of the magnetization on the nanometer\nlength scale remains challenging. Here, we demonstrate how magnetic domain\npatterns in a Tm-doped yttrium iron garnet (Tm:YIG) thin film with\nperpendicular magnetic anisotropy can be permanently and locally imprinted by\nhigh intensity photon pulses of a hard x-ray transient grating (XTG).\nMicromagnetic simulations provide a qualitative understanding of the observed\nchanges in the orientation of magnetic domains in Tm:YIG and XTG-induced\nchanges. The presented results offer a route for the local manipulation of the\nmagnetic state using hard XTG."
    },
    {
        "anchor": "Nanoscale Heat Transfer: from Computation to Experiment: Heat transfer can differ distinctly at the nanoscale from that at the\nmacroscale. Recent advancement in computational and experimental techniques has\nenabled a large number of interesting observations and understanding of heat\ntransfer processes at the nanoscale. In this review, we will first discuss\nrecent advances in computational and experimental methods used in nanoscale\nthermal transport studies, followed by reviews of novel thermal transport\nphenomena at the nanoscale observed in both computational and experimental\nstudies, and discussion on current understanding of these novel phenomena. Our\nperspectives on challenges and opportunities on computational and experimental\nmethods are also presented.",
        "positive": "Giant anisotropic magnetoresistance with dual-four-fold symmetry in\n  CaMnO3/CaIrO3 heterostructures: The realization of four-fold anisotropic magnetoresistance (AMR) in novel\n3d-5d heterostructures has boosted major efforts in antiferromagnetic\nspintronics. However, despite the potential of incorporating strong spin-orbit\ncoupling, only small AMR signals have been detected thus far, prompting a\nsearch for new mechanisms to enhance the signal. In this study on CaMnO3/CaIrO3\nheterostructures, we report a unique dual-four-fold symmetric 70% AMR; a signal\ntwo orders of magnitude larger than previously observed in similar systems. We\nfind that one order is enhanced by tuning a large biaxial anisotropy through\noctahedral tilts of similar sense in the constituent layers, while the second\norder is triggered by a spin-flop transition in a nearly Mott-type phase.\nDynamics between these two phenomena as evidenced by the step-like AMR and a\nsuperimposed biaxial-anisotropy-induced AMR capture a subtle interplay of\npseudospin coupling with the lattice and external magnetic field. Our study\nshows that a combination of charge-transfer, interlayer coupling, and a\nspin-flop transition can yield a giant AMR relevant for sensing and\nantiferromagnetic memory applications."
    },
    {
        "anchor": "Large Electronic Anisotropy and Enhanced Chemical Activity of Highly\n  Rippled Phosphorene: We investigate the electronic structure and chemical activity of rippled\nphosphorene induced by large compressive strains via first-principles\ncalculation. It is found that phosphorene is extraordinarily bendable, enabling\nthe accommodation of ripples with large curvatures. Such highly rippled\nphosphorene shows a strong anisotropy in electronic properties. For ripples\nalong the armchair direction, the band gap changes from 0.84 to 0.51 eV for the\ncompressive strain up to -20% and further compression shows no significant\neffect, for ripples along the zigzag direction, semiconductor to metal\ntransition occurs. Within the rippled phosphorene, the local electronic\nproperties, such as the modulated band gap and the alignments of frontier\norbitals, are found to be highly spatially dependent, which may be used for\nmodulating the injection and confinement of carriers for optical and\nphotovoltaic applications. The examination of the interaction of a physisorbed\nNO molecule with the rippled phosphorene under different compressive strains\nshows that the chemical activities of the phosphorene are significantly\nenhanced at the top and bottom peaks of the ripples, indicated by the enhanced\nadsorption and charge transfer between them. All these features can be ascribed\nto the effect of curvatures, which modifies the orbital coupling between atoms\nat the ripple peaks.",
        "positive": "Spatially resolved photoluminescence analysis of Se passivation and\n  defect formation in CdSe$_{x}$Te$_{1-x}$ thin films: CdTe is the most commercially successful thin-film photovoltaic technology to\ndate. The recent development of Se-alloyed CdSe$_{x}$Te$_{1-x}$ layers in CdTe\nsolar cells has led to higher device efficiencies, due to a lowered bandgap\nimproving the photocurrent, improved voltage characteristics and longer carrier\nlifetimes. Evidence from cross-sectional electron microscopy is widely believed\nto indicate that Se passivates defects in CdSe$_{x}$Te$_{1-x}$ solar cells, and\nthat this is the reason for better lifetimes and voltages in these devices.\nHere, we utilise spatially resolved photoluminescence measurements of\nCdSe$_{x}$Te$_{1-x}$ thin films on glass to study the effects of Se on carrier\nrecombination in the material, isolated from the impact of conductive\ninterfaces and without the need to prepare cross-sections through the samples.\nWe find further evidence to support Se passivation of grain boundaries, but\nalso identify an associated increase in below-bandgap photoluminescence that\nindicates the presence of Se-enhanced luminescent defects. Our results show\nthat Se treatment, in tandem with Cl passivation, does increase radiative\nefficiencies. However, the simultaneous enhancement of defects within the grain\ninteriors suggests that although it is overall beneficial, Se incorporation may\nstill ultimately limit the maximum attainable efficiency of\nCdSe$_{x}$Te$_{1-x}$ solar cells."
    },
    {
        "anchor": "Magneto-caloric effect in the pseudo-binary intermetallic YPrFe17\n  compound: We have synthesized the intermetallic YPrFe17 compound by arc-melting. X-ray\nand neutron powder diffraction show that the crystal structure is rhombohedral\nwith View the MathML source space group (Th2Zn17-type). The investigated\ncompound exhibits a broad isothermal magnetic entropy change {\\Delta}SM(T)\nassociated with the ferro-to-paramagnetic phase transition (TC \\approx 290 K).\nThe |{\\Delta}SM| (\\approx 2.3 J kg-1 K-1) and the relative cooling power\n(\\approx 100 J kg-1) have been calculated for applied magnetic field changes up\nto 1.5 T. A single master curve for {\\Delta}SM under different values of the\nmagnetic field change can be obtained by a rescaling of the temperature axis.\nThe results are compared and discussed in terms of the magneto-caloric effect\nin the isostructural R2Fe17 (R = Y, Pr and Nd) binary intermetallic alloys.",
        "positive": "Muonium state exchange dynamics in n-type Gallium Arsenide: Muonium (Mu), a pseudo-isotope atom of hydrogen with a positively charged\nmuon at the place of the proton, can form in a wide range of semiconductor\nmaterials. They can appear in different states, depending on their charge state\nand microscopic site within a crystal lattice. After the Mu formation, they\nundergo interactions with free charge carriers, electronic spins, and other Mu\nsites, and form a dynamic network of state exchange. We identified the model of\nMu dynamics in n-type Gallium Arsenide using the density matrix simulation and\nphotoexcited muon spin spectroscopy technique. Fitting to the dark and\nilluminated $\\mu$SR data provided transition rates between Mu states, which in\nturn showed the underlying mechanism of the $\\mu$SR time spectra. Deduced\ncapture/scattering cross sections of the Mu states reflected the microscopic\ndynamics of Mu. Illumination studies enable us to measure interactions between\nMu and generated minority carriers, which are unavailable in dark measurements.\nThe methodology we developed in this study can be applied to other\nsemiconductor systems for a deeper microscopic understanding of the Mu state\nexchange dynamics."
    },
    {
        "anchor": "The building blocks of magnonics: Novel material properties can be realized by designing waves' dispersion\nrelations in artificial crystals. The crystal's structural length scales may\nrange from nano- (light) up to centimeters (sound waves). Because of their\nemergent properties these materials are called metamaterials. Different to\nphotonics, where the dielectric constant dominantly determines the index of\nrefraction, in a ferromagnet the spin-wave index of refraction can be\ndramatically changed already by the magnetization direction. This allows a\ndifferent flexibility in realizing dynamic wave guides or spin-wave switches.\nThe present review will give an introduction into the novel functionalities of\nspin-wave devices, concepts for spin-wave based computing and magnonic\ncrystals. The parameters of the magnetic metamaterials are adjusted to the\nspin-wave k-vector such that the magnonic band structure is designed. However,\nalready the elementary building block of an antidot lattice, the singular hole,\nowns a strongly varying internal potential determined by its magnetic dipole\nfield and a localization of spin-wave modes. Photo-magnonics reveal a way to\ninvestigate the control over the interplay between localization and\ndelocalization of the spin-wave modes using femtosecond lasers, which is a\nmajor focus of this review. We will discuss the crucial parameters to realize\nfree Bloch states and how, by contrast, a controlled localization might allow\nto gradually turn on and manipulate spin-wave interactions in spin-wave based\ndevices in the future.",
        "positive": "Effects of spin current on ferromagnets: When a spin-polarized current flows through a ferromagnet, the local\nmagnetization receives a spin torque. Two consequences of this spin torque are\nstudied. First, the uniformly magnetized ferromagnet becomes unstable if a\nsufficiently large current is applied. The characteristics of the instability\ninclude spin wave generation and magnetization chaos. Second, the spin torque\nhas profound effects on the structure and dynamics of the magnetic domain wall.\nA detail analysis on the domain wall mass, kinetic energy and wall depinning\nthreshold is given."
    },
    {
        "anchor": "Sustainability of large scale waste heat harvesting using thermoelectric: The amount of waste heat exergy generated globally is 69.058 EJ which can be\ndivided into, low temperature 373 K, 30.496 EJ, medium temperature 373 K to 573\nK, 14.431 EJ and high temperature 573 K, 24.131 EJ. These values of exergy have\nbeen used to determine the minimum number of pn junctions required to convert\nthe exergy into electrical power. It is found that the number of junctions\nrequired to convert high temperature exergy increases from 8.22x10^11 to\n24.66x10^11 when the aspect ratio of the legs increases from 0.5 cm^1 to 1.5\ncm^1. To convert the low temperature exergy, 81.76x10^11 to 245.25x10^11\njunctions will be required depending on the legs aspect ratio. The quantity of\nalloys containing elements such as Pb, Bi, Te, Sb, Se and Sn required to\nsynthesize these junctions therefore is of the order of millions of tons which\nmeans the elements required is also of similar magnitude. The current world\nproduction of these elements however falls far short of this requirement,\nindicating significant supply chain risk. The production of these elements,\neven if resources are available, will emit millions of tons of CO2 showing that\ncurrent alloys are non-sustainable for waste heat recovery.",
        "positive": "Discarded gems: Thermoelectric performance of materials with band gap\n  emerging at the hybrid-functional level: A finite electronic band gap is a standard filter in high-throughput\nscreening of materials using density functional theory (DFT). However, because\nof the systematic underestimation of band gaps in standard DFT approximations,\na number of compounds may incorrectly be predicted metallic. In a more accurate\ntreatment, such materials may instead appear as low band gap materials and\ncould e.g. have good thermoelectric properties if suitable doping is feasible.\nTo explore this possibility, we performed hybrid functional calculations on\n1093 cubic materials listed in the MaterialsProjects database with four atoms\nin the primitive unit cell, spin-neutral ground state, and a formation energy\nwithin 0.3 eV of the convex hull. Out of these materials, we identified eight\ncompounds for which a finite band gap emerges. Evaluating electronic and\nthermal transport properties of these compounds, we found the compositions\nMgSc2 Hg and Li2 CaSi to exhibit promising thermoelectric properties. These\nfindings underline the potential of reassessing band gaps and band structures\nof compounds to indentify additional potential thermoelectric materials."
    },
    {
        "anchor": "Formation of Curved Micron-Sized Single Crystals: Crystals in nature often demonstrate curved morphologies rather than\nclassical faceted surfaces. Inspired by biogenic curved single crystals, we\ndemonstrate that gold single crystals exhibiting curved surfaces can be grown\nwith no need of any fabrication steps. These single crystals grow from the\nconfined volume of a droplet of a eutectic composition melt which forms via the\ndewetting of nanometric thin films. We can control their curvature by\ncontrolling the environment in which the process is carried out, including\nseveral parameters, such as the contact angle and the curvature of the drops by\nchanging the surface tension of the liquid drop during crystal growth. Here we\npresent an energetic model that explains this phenomenon and predicts why and\nunder what conditions crystals will be forced to grow with the curvature of the\nmicro droplet even though the energetic state of a curved single crystal is\nvery high.",
        "positive": "Unconventional approaches to combine optical transparency with\n  electrical conductivity: Combination of electrical conductivity and optical transparency in the same\nmaterial -- known to be a prerogative of only a few oxides of post-transition\nmetals, such as In, Sn, Zn and Cd -- manifests itself in a distinctive band\nstructure of the transparent conductor host. While the oxides of other elements\nwith $s^2$ electronic configuration, for example, Mg, Ca, Sc and Al, also\nexhibit the desired optical and electronic features, they have not been\nconsidered as candidates for achieving good electrical conductivity because of\nthe challenges of efficient carrier generation in these wide-bandgap materials.\nHere we demonstrate that alternative approaches to the problem not only allow\nattaining the transport and optical properties which compete with those in\ncurrently utilized transparent conducting oxides (TCO), but also significantly\nbroaden the range of materials with a potential of being developed into novel\nfunctional transparent conductors."
    },
    {
        "anchor": "Quantifying Atom-scale Dopant Movement and Electrical Activation in Si:P\n  Monolayers: Advanced hydrogen lithography techniques and low-temperature epitaxial\novergrowth enable patterning of highly phosphorus-doped silicon (Si:P)\nmonolayers (ML) with atomic precision. This approach to device fabrication has\nmade Si:P monolayer systems a testbed for multiqubit quantum computing\narchitectures and atomically precise 2-D superlattice designs whose behaviors\nare directly tied to the deterministic placement of single dopants. However,\ndopant segregation, diffusion, surface roughening, and defect formation during\nthe encapsulation overgrowth introduce large uncertainties to the exact dopant\nplacement and activation ratio. In this study, we develop a unique method by\ncombining dopant segregation/diffusion models with sputter profiling simulation\nto monitor and control, at the atomic scale, dopant movement using\nroom-temperature grown locking layers (LL). We explore the impact of LL growth\nrate, thickness, rapid thermal anneal, surface accumulation, and growth front\nroughness on dopant confinement, local crystalline quality, and electrical\nactivation within Si:P 2-D systems. We demonstrate that dopant movement can be\nmore efficiently suppressed by increasing the LL growth rate than by increasing\nLL thickness. We find that the dopant segregation length can be suppressed\nbelow a single Si lattice constant by increasing LL growth rates at room\ntemperature while maintaining epitaxy. Although dopant diffusivity within the\nLL is found to remain high even below the hydrogen desorption temperature, we\ndemonstrate that exceptionally sharp dopant confinement with high electrical\nquality within Si:P monolayers can be achieved by combining a high LL growth\nrate with a low-temperature LL rapid thermal anneal.",
        "positive": "Topological Quantum Materials for Energy Conversion and Storage: Topological quantum materials (TQMs) have symmetry protected band structures\nwith useful electronic properties that have applications in information,\nsensing, energy, and other technologies. In the past 10 years, the applications\nof TQMs in the field of energy conversion and storage mainly including water\nsplitting, ethanol electro-oxidation, battery, supercapacitor, and relative\nenergy-efficient devices have attracted increasing attention. The novel quantum\nstates in TQMs provide a stable electron bath with high conductivity and\ncarrier mobility, long lifetime, and determined spin states, making TQMs an\nideal platform for understanding the surface reactions and looking for highly\nefficient materials for energy conversion and storage. In this Perspective, we\npresent an overview of the recent progress regarding topological quantum\ncatalysis. We describe the open problems, and the potential applications of\nTQMs in water splitting, batteries, supercapacitors, and other prospects in\nenergy conversion and storage."
    },
    {
        "anchor": "Ab initio study of canted magnetism of finite atomic chains at surfaces: By using ab initio methods on different levels we study the magnetic ground\nstate of (finite) atomic wires deposited on metallic surfaces. A\nphenomenological model based on symmetry arguments suggests that the\nmagnetization of a ferromagnetic wire is aligned either normal to the wire and,\ngenerally, tilted with respect to the surface normal or parallel to the wire.\n  From a first principles point of view, this simple model can be best related\nto the so--called magnetic force theorem calculations being often used to\nexplore magnetic anisotropy energies of bulk and surface systems. The second\ntheoretical approach we use to search for the canted magnetic ground state is\nfirst principles adiabatic spin dynamics extended to the case of fully\nrelativistic electron scattering. First, for the case of two adjacent Fe atoms\nan a Cu(111) surface we demonstrate that the reduction of the surface symmetry\ncan indeed lead to canted magnetism. The anisotropy constants and consequently\nthe ground state magnetization direction are very sensitive to the position of\nthe dimer with respect to the surface. We also performed calculations for a\nseven--atom Co chain placed along a step edge of a Pt(111) surface. As far as\nthe ground state spin orientation is concerned we obtain excellent agreement\nwith experiment. Moreover, the magnetic ground state turns out to be slightly\nnoncollinear.",
        "positive": "On the thermodynamic aspect of zinc oxide polymorphism. Calorimetric\n  study of metastable rock salt ZnO: The enthalpies of dissolution of metastable rock salt and thermodynamically\nstable wurtzite polymorphs of zinc oxide in aqueous H2SO4 have been measured in\ndirect calorimetric experiments at 303 K and 0.1 MPa and the obtained results\nenabled determination of the standard enthalpy of the rock salt-to-wurtzite\nphase transition in ZnO, {\\Delta}trH = -11.7+/-0.3 kJ/mol."
    },
    {
        "anchor": "Non-Abelian Stokes theorem and quantized Berry flux: Band topology of anomalous quantum Hall insulators can be precisely addressed\nby computing Chern numbers of constituent non-degenerate bands that describe\nquantized, Abelian Berry flux through two-dimensional Brillouin zone. Can Chern\nnumbers be defined for $SU(2)$ Berry connection of two-fold degenerate bands of\nmaterials preserving space-inversion ($\\mathcal{P}$) and time-reversal\n($\\mathcal{T}$) symmetries or combined $\\mathcal{PT}$ symmetry, without\ndetailed knowledge of underlying basis? We affirmatively answer this question\nby employing a non-Abelian generalization of Stokes' theorem and describe a\nmanifestly gauge-invariant method for computing magnitudes of quantized $SU(2)$\nBerry flux (spin-Chern number) from eigenvalues of Wilson loops. The power of\nthis method is elucidated by performing $\\mathbb{N}$-classification of \\emph{ab\ninitio} band structures of three-dimensional, Dirac materials. Our work\noutlines a unified framework for addressing first-order and higher-order\ntopology of insulators and semimetals, without relying on detailed symmetry\ndata.",
        "positive": "Employing semilocal exchange hole with an application to meta-GGA level\n  screened range separated hybrid functional: A conventional wisdom method: Range separated hybrid density functionals are very successful in describing\na wide range of molecular and solid state properties accurately. Range\nseparated hybrid functionals are designed from spherically averaged or system\naveraged reversed engineered exchange hole. In the present attempt, we employ\nscreened range separated hybrid functional scheme to the meta-GGA rung by using\nTao-Mo semilocal exchange hole (or functional). The hybrid functional proposed\nhere utilizes the spherically averaged density matrix expansion based exchange\nhole in range separation scheme. For slowly varying density correction, we\nemploy range separation scheme only through the local density approximation\n(LDA) based exchange hole coupled with the slowly varying Tao-Mo enhancement\nfactor through the conventional wisdom technique. Comprehensive performance and\ntesting of the present functional shows, it accurately describes several\nmolecular properties. The most appealing feature of this present screened\nhybrid functional is that it will be practically very useful in describing\nsolid state properties in meta-GGA level."
    },
    {
        "anchor": "Inequivalent quantization in the field of a ferromagnetic wire: We argue that it is possible to bind neutral atom (NA) to the ferromagnetic\nwire (FW) by inequivalent quantization of the Hamiltonian. We follow the well\nknown von Neumann's method of self-adjoint extensions (SAE) to get this\ninequivalent quantization, which is characterized by a parameter\n\\Sigma\\in\\mathbb{R}({mod}2\\pi). There exists a single bound state for the\ncoupling constant \\eta^2\\in[0,1). Although this bound state should not occur\ndue to the existence of classical scale symmetry in the problem. But since\nquantization procedure breaks this classical symmetry, bound state comes out as\na scale in the problem leading to scaling anomaly. We also discuss the strong\ncoupling region \\eta^2< 0, which supports bound state making the problem\nre-normalizable.",
        "positive": "Strengthening gold-gold bonds by complexing gold clusters with noble\n  gases: We report an unexpectedly strong and complex chemical bonding of rare-gas\natoms to neutral gold clusters. The bonding features are consistently\nreproduced at different levels of approximation within density-functional\ntheory and beyond: from GGA, through hybrid and double-hybrid functionals, up\nto renormalized second-order perturbation theory. The main finding is that the\nadsorption of Ar, Kr, and Xe reduces electron-electron repulsion within gold\ndimer, causing strengthening of the Au-Au bond. Differently from the dimer, the\nrare-gas adsorption effects on the gold trimer's geometry and vibrational\nfrequencies are mainly due to electron occupation of the trimer's lowest\nunoccupied molecular orbital. For the trimer, the theoretical results are also\nconsistent with far-infrared multiple photon dissociation experiments."
    },
    {
        "anchor": "Anatomy of spin Hall effect in ferromagnetic metals: The spin Hall effect in nonmagnetic materials has been intensively studied\nand became one of the most crucial spin-charge conversion mechanism in\nspintronics. However, the spin Hall effect in ferromagnetic metals has been\nless investigated and remains unclear. In this work, we investigate the spin\nHall effect in representative ferromagnetic alloy by using first-principles\ncalculations. We first clarify the spin Hall effect into three different types\nincluding conventional (CSHE), spin anomalous (SAHE) and magnetic spin Hall\neffect (MSHE) and then calculate the corresponding spin Hall conductivity and\nspin Hall angle for (Fe, Co, Ni)Pt, NiFe and CoFe alloy. We find the above\nthree spin Hall mechanisms do coexist in ferromagnetic metals. Particularly,\nfor Pt-based ferromagnetic alloy, a sizable conventional and magnetic spin Hall\nangles comparable to that of Pt have been predicted. The remarkable\nunconventional spin Hall effect in ferromagnetic metal may enrich the\nspin-charge conversion phenomena. For instance, the spin current generated by\nremarkable MSHE with out-of-plane spin-polarization should be helpful for\nfield-free switching of perpendicular magnetization through spin-orbit torque\neffect. This work may stimulate future studies on the spin Hall effect in\nferromagnetic metals and pave their promising applications for spin-charge\nconversion devices in spintronics.",
        "positive": "Towards ferroelectrically-controlled magnetism: Magnetoelectric effect\n  in Fe/BaTiO3 multilayers: An unexplored physical mechanism which produces a magnetoelectric effect in\nferroelectric/ferromagnetic multilayers is studied based on first-principles\ncalculations. Its origin is a change in bonding at the\nferroelectric/ferromagnet interface that alters the interface magnetization\nwhen the electric polarization reverses. Using Fe/BaTiO3 multilayers as a\nrepresentative model we show a sizable difference in magnetic moments of Fe and\nTi atoms at the two interfaces dissimilar by the orientation of the local\nelectric dipole moment. The predicted magnetoelectric effect is comparable in\nmagnitude with that observed in elastically-coupled composites and opens a new\ndirection to control magnetic properties of thin-film layered structures by\nelectric fields."
    },
    {
        "anchor": "Evaluating the System Compliance in Testing Carbon Nanotube Fibers: System compliances of two testing machines (Keysight T150 and Instron 3365)\nwere studied for the tensile testing of carbon nanotube (CNT) fibers. Due to\nthe different gripping methods, the T150's system compliance was nearly zero,\nwhile that of the Instron was nonnegligible. By analyzing the data dispersion\nwith the Weibull theory, a safe gauge length of >10 mm was suggested for CNT\nfibers. Therefore, a standard test procedure should involve the compliance\nevaluation, choice of gauge length, and Weibull statistical analysis.",
        "positive": "Novel Scintillation Material - ZnO Transparent Ceramics: ZnO-based scintillation ceramics for application in HENPA LENPA analyzers\nhave been investigated. The following ceramic samples have been prepared:\nundoped ones (ZnO), an excess of zinc in stoichiometry (ZnO:Zn), doped with\ngallium (ZnO:Ga) and lithium (ZnO:Li). Optical transmission, x-ray excited\nemission, scintillation decay and pulse height spectra were measured and\nanalyzed. Ceramics have reasonable transparency in visible range (up to 60% for\n0.4 mm thickness) and energy resolution (14.9% at 662 keV Cs137 gamma\nexcitation). Undoped ZnO shows slow (1.6 {\\mu}s) luminescence with maximum at\n2.37 eV and light yield about 57% of CsI:Tl. ZnO:Ga ceramics show relatively\nlow light yield with ultra fast decay time (1 ns). Lithium doped ceramics\nZnO:Li have better decay time than undoped ZnO with fair light yield. ZnO:Li\nceramics show good characteristics under alpha-particle excitation and can be\napplied for the neutral particle analyzers."
    },
    {
        "anchor": "ADAQ-SYM: Automated Symmetry Analysis of Defect Orbitals: Quantum technologies like single photon emitters and qubits can be enabled by\npoint defects in semiconductors, with the NV-center in diamond being the most\nprominent example. There are many different semiconductors, each potentially\nhosting interesting defects. High-throughput methods and automated workflows\nbecome necessary when searching for novel point defects in a large chemical\nspace. The symmetry properties of the point defect orbitals can yield useful\ninformation about the behavior of the system, such as the interaction with\npolarized light. We have developed an automated code to perform symmetry\nanalysis of point defect orbitals obtained by plane-wave density functional\ntheory simulations. The code, named ADAQ-SYM, calculates the characters for\neach orbital, finds the irreducible representations, and uses selection rules\nto find which optical transitions are allowed. The capabilities of ADAQ-SYM are\ndemonstrated on several defects in diamond and 4H-SiC. The symmetry analysis\nexplains the different zero phonon line (ZPL) polarization of the hk and kh\ndivacancies in 4H-SiC. ADAQ-SYM is automated, making it suitable for\nhigh-throughput screening of point defects.",
        "positive": "An alternative to the topological interpretation of the transverse\n  resistivity anomalies in SrRuO3: We clarify the physical origin of anomalies in transverse resistivity often\nobserved in exotic materials, such as SrRuO3, in which the Berry curvature is\nmanifested in the transport properties. The previously attributed mechanism for\nthe anomalies, the topological Hall effect (THE), is refuted by our thorough\ninvestigations as well as formulation of a model considering inhomogeneous\nmagnetoelectric properties in the material. Our analyses fully explain every\nfeature of the anomalies without resorting to the THE. The present results\nestablish a fundamental understanding, which was previously overlooked, of\nmagneto-transport properties in such exotic materials."
    },
    {
        "anchor": "Magic Graphene Clusters Formation in the graphene CVD growth process on\n  Ru and Rh: To improve atomically controlled chemical vapor deposition (CVD) growth of\ngraphene, understanding the evolution from various carbon species to a graphene\nnuclei on various catalyst surfaces is essential. Experimentally, an\nultra-stable carbon cluster on Ru(0001), Rh(111) surfaces was observed, while\nits structure and formation process were still under highly debate. Using ab\ninitio calculations and kinetic analyses, we disclosed a specific type of\ncarbon clusters, composed of a C21 core and a few dangling C atoms around, were\nexceptional stable in the size range from 21 to 27. The most stable one of\nthem, an isomer of C24 characterized as three dangling C atoms attached to the\nC21 (denoted as C21-3C), is the most promising candidate for the experimental\nobservation. The ultra-stability of C21-3C originates from both the stable core\nand the appropriate passivation of dangling carbon atoms by the catalyst\nsurface.",
        "positive": "Electric field switching of the uniaxial magnetic anisotropy of an\n  antiferromagnet: Electric field control of magnetic anisotropy in ferromagnets has been\nintensively pursued in spintronics to achieve efficient memory and computing\ndevices with low energy consumption. Compared with ferromagnets,\nantiferromagnets hold huge potential in high-density information storage for\ntheir ultrafast spin dynamics and vanishingly small stray field. However, the\nswitching of magnetic anisotropy of antiferromagnets via electric field remains\nelusive. Here we use ferroelastic strain from piezoelectric materials to switch\nthe uniaxial magnetic anisotropy and the N\\'eel order reversibly in\nantiferromagnetic Mn2Au films with an electric field of only a few kV/cm at\nroom temperature. Owing to the uniaxial magnetic anisotropy, a ratchet-like\nswitching behavior driven by the N\\'eel spin-orbit torque is observed in the\nMn2Au, which can be reversed by electric fields."
    },
    {
        "anchor": "Toward accurate polarization estimation in nanoscopic systems: The nanoscopic characterization of ferroelectric thin films is crucial from\ntheir device application point of view. Standard characterization techniques\nare based on detecting the nanoscopic charge compensation current (switching\ncurrent) caused by the polarization reversal in the ferroelectric. Owing to\nvarious surface and bulk limited mechanisms, leakage currents commonly appear\nduring such measurements, which are frequently subtracted using the device I-V\ncharacteristic by employing positive-up-negative-down (PUND) measurement\nscheme. By performing nanoscopic switching current measurements on a commonly\nused ferroelectric, BiFeO3, we show that such characterization methods may be\nprone to large errors in the polarization estimation on ferro-resistive\nsamples, due to current background subtraction issues. Especially, when\nferro-resistive behavior is associated with the polarization reversal of the\nferroelectric thin film, background current subtraction is not accurate due to\nthe mismatch of the I-V characteristics for the two polarization states. We\nshow instead that removing the background current by an asymmetric least\nsquares subtraction method, though not perfect, gives a much better estimation\nof the ferroelectric properties of the sample under study.",
        "positive": "Dynamics of a first order electronic phase transition in manganites: By reducing an electronically phase separated manganite\n(La[1-y]Pr[y])[x]Ca[1-x]MnO3 single crystal thin film to dimensions on the\norder of the inherent phase domains, it is possible to isolate and monitor the\nbehavior of single domains at a first order transition. At this critical point,\nit is possible to study the coexistence, formation and annihilation processes\nof discrete electronic phase domains. With this technique, we make several new\nobservations on the mechanisms leading to the metal insulator transition in\nmanganites. We observe that domain formation is emergent and random, the\ntransition process from the metallic phase to the insulating phase takes longer\nthan the reverse process, electric field effects are more influential in\ndriving a phase transition than current induced electron heating, and single\ndomain transition dynamics can be tuned through careful application of\ntemperature and electric field."
    },
    {
        "anchor": "Population Inversion in Monolayer and Bilayer Graphene: The recent demonstration of saturable absorption and negative optical\nconductivity in the Terahertz range in graphene has opened up new opportunities\nfor optoelectronic applications based on this and other low dimensional\nmaterials. Recently, population inversion across the Dirac point has been\nobserved directly by time- and angle-resolved photoemission spectroscopy\n(tr-ARPES), revealing a relaxation time of only ~ 130 femtoseconds. This\nseverely limits the applicability of single layer graphene to, for example,\nTerahertz light amplification. Here we use tr-ARPES to demonstrate long-lived\npopulation inversion in bilayer graphene. The effect is attributed to the small\nband gap found in this compound. We propose a microscopic model for these\nobservations and speculate that an enhancement of both the pump photon energy\nand the pump fluence may further increase this lifetime.",
        "positive": "Individual Barkhausen pulses of ferroelastic nanodomains: Ferroelectric materials, upon electric field biasing, display polarization\ndiscontinuities known as Barkhausen jumps, a subclass of a more general\nphenomenon known as crackling noise. Herein, we follow at the nanoscale the\nmotion of 90 degree needle domains induced by an electric field applied in the\npolarization direction of the prototypical ferroelectric BaTiO3, inside a\ntransmission electron microscope. The nature of motion and periodicity of\nBarkhausen pulses leads to real-time visualization of distinctive interaction\nmechanisms of the domains with each other but without coming into contact, a\nmechanism that has not been observed before, or/and with the lattice where the\ndomain walls appear to be moving through the dielectric medium relatively\nfreely, experiencing weak Peierls-like potentials. Control over the kinetics of\nferroelastic domain wall motion can lead to novel nanoelectronic devices\npertinent to computing and storage applications."
    },
    {
        "anchor": "Elucidation of Relaxation Dynamics Beyond Equilibrium Through\n  AI-informed X-ray Photon Correlation Spectroscopy: Understanding and interpreting dynamics of functional materials \\textit{in\nsitu} is a grand challenge in physics and materials science due to the\ndifficulty of experimentally probing materials at varied length and time\nscales. X-ray photon correlation spectroscopy (XPCS) is uniquely well-suited\nfor characterizing materials dynamics over wide-ranging time scales, however\nspatial and temporal heterogeneity in material behavior can make interpretation\nof experimental XPCS data difficult. In this work we have developed an\nunsupervised deep learning (DL) framework for automated classification and\ninterpretation of relaxation dynamics from experimental data without requiring\nany prior physical knowledge of the system behavior. We demonstrate how this\nmethod can be used to rapidly explore large datasets to identify samples of\ninterest, and we apply this approach to directly correlate bulk properties of a\nmodel system to microscopic dynamics. Importantly, this DL framework is\nmaterial and process agnostic, marking a concrete step towards autonomous\nmaterials discovery.",
        "positive": "Graphene Based Terahertz Phase Modulators: Electrical control of amplitude and phase of terahertz radiation (THz) is the\nkey technological challenge for high resolution and noninvasive THz imaging.\nThe lack of an active materials and devices hinders the realization of these\nimaging systems. Here, we demonstrate an efficient terahertz phase and\namplitude modulation using electrically tunable graphene devices. Our device\nstructure consists of electrolyte-gated graphene placed at quarter wavelength\ndistance from a reflecting metallic surface. In this geometry, graphene\noperates as a tunable impedance surface which yields electrically controlled\nreflection phase. Terahertz time domain reflection spectroscopy reveals the\nvoltage controlled phase modulation of {\\pi} and the reflection modulation of\n50 dB. To show the promises of our approach, we demonstrate a multipixel phase\nmodulator array which operates as a gradient impedance surface."
    },
    {
        "anchor": "Island diffusion on metal fcc(100) surfaces: We present Monte Carlo simulations for the size and temperature dependence of\nthe diffusion coefficient of adatom islands on the Cu(100) surface. We show\nthat the scaling exponent for the size dependence is not a constant but a\ndecreasing function of the island size and approaches unity for very large\nislands. This is due to a crossover from periphery dominated mass transport to\na regime where vacancies diffuse inside the island. The effective scaling\nexponents are in good agreement with theory and experiments.",
        "positive": "Near infra-red optical materials from polymeric amorphous carbon\n  synthesised by collisional plasma process: The synthesis of polymer-like amorphous carbon (a-C:H) thin-films by\nmicrowave excited collisional hydrocarbon plasma process is reported. Stable\nand highly aromatic a-C:H were obtained containing significant inclusions of\npoly(p-phenylene vinylene) (PPV). PPV confers universal optoelectronic\nproperties to the synthesised material. That is a-C:H with tailor-made\nrefractive index are capable of becoming absorption-free in visible (red) -\nnear infrared wavelength range. Production of large aromatic hydrocarbon\nincluding phenyl clusters and/or particles is attributed to enhanced\ncoagulation of elemental plasma species under collisional plasma conditions.\nDetailed structural and morphological changes that occur in a-C:H during the\nplasma synthesis are also described."
    },
    {
        "anchor": "Detection of the onset of yielding and creep failure from digital image\n  correlation: There are a multitude of applications in which structural materials would be\ndesired to be nondestructively evaluated, while in a component, for plasticity\nand failure characteristics. In this way, safety and resilience features can be\nsignificantly improved. Nevertheless, while failure can be visible through\ncracks, plasticity is commonly invisible and highly microstructure-dependent.\nHere, we show that an equation-free method based on principal component\nanalysis is capable of detecting yielding and tertiary creep onset, directly\nfrom strain fields that are obtained by digital image correlation, applicable\non components, continuously and nondestructively. We demonstrate the\napplicability of the method to yielding of Ni-based Haynes 230 metal alloy\npolycrystalline samples, which are also characterized through electron\nmicroscopy and benchmarked using continuum polycrystalline plasticity modeling.\nAlso, we successfully apply this method to yielding during uniaxial tension of\nHastelloy X polycrystalline samples, and also to the onset of tertiary creep in\nquasibrittle fiber composites under uniaxial tension. We conclude that there\nare key features in the spatiotemporal fluctuations of local strain fields that\ncan be used to infer mechanical properties.",
        "positive": "Exact Microtheoretical Approach to Calculation of Optical Properties of\n  Ultralow Dimensional Crystals: The main problem in theoretical analysis of structures with strong\nconfinement is the fact that standard mathematical tools: differential\nequations and Fourier's transformations are no longer applicable. In this paper\nwe have demonstrated that method of Green's functions can be successfully used\non low-dimension crystal samples, as a consequence of quantum size effects. We\ncan illustrate modified model through the prime cubic structure molecular\ncrystal: bulk and ultrathin film. Our analysis starts with standard exciton\nHamiltonian with definition of commutative Green's function and equation of\nmotion. We have presented detailed procedure of calculations of Green's\nfunctions, and further dispersion law, distribution of states and relative\npermittivity for bulk samples. After this, we have followed the same procedures\nfor obtaining the properties of excitons in ultra-thin films. The results have\nbeen presented graphically. Besides modified method of Green's functions we\nhave shown that the exciton energy spectrum is discrete in film structures\n(with number of energy levels equal to the number of atomic planes of the\nfilm). Compared to the bulk structures, with continual absorption zone, in film\nstructures exist resonant absorption peaks. With increased film thickness\ndifferences between bulk and film vanish."
    },
    {
        "anchor": "Chemical and nuclear catalysis driven by localized anharmonic vibrations: In many-body nonlinear systems with sufficient anharmonicity, a special kind\nof lattice vibrations, namely, Localized Anharmonic Vibrations (LAV) can be\nexcited either thermally or by external triggering, in which the amplitude of\natomic oscillations greatly exceeds that of harmonic oscillations (phonons)\nthat determine the system temperature. Coherency and persistence of LAV may\nhave drastic effect on chemical and nuclear reaction rates due to time-periodic\nmodulation of reaction sites. One example is a strong acceleration of chemical\nreaction rates driven by thermally-activated \"jumps\" over the reaction barrier\ndue to the time-periodic modulation of the barrier height in the LAV vicinity.\nAt sufficiently low temperatures, the reaction rate is controlled by quantum\ntunneling through the barrier rather than by classical jumping over it. A giant\nincrease of sub-barrier transparency was demonstrated for a parabolic potential\nwell with the time-periodic eigenfrequency, when the modulation frequency\nexceeds the eigenfrequency by a factor of ~2 (parametric regime). Such regime\ncan be realized for a hydrogen or deuterium atom in metal hydrides/deuterides,\nsuch as NiH or PdD, in the vicinity of LAV. We present an analytical solution\nof the Schrodinger equation for a nonstationary harmonic oscillator, analyze\nthe parametric regime in details and discuss its applications to the tunnel\neffect and to D-D fusion in PdD lattice. We obtain simple analytical\nexpressions for the increase of amplitude and energy of zero-point oscillations\n(ZPO) induced by the parametric modulation. Based on that, we demonstrate a\ndrastic increase of the D-D fusion rate with in-creasing number of modulation\nperiods evaluated in the framework of Schwinger model, which takes into account\nsuppression of the Coulomb barrier due to lattice vibrations.",
        "positive": "Non-constant crack tip opening angle and negligible crack tunneling of\n  brittle fracture in Al: A first-principles prediction: Numerous measurements showed that the crack tip opening angle (CTOA) is\nnearly constant upon stable ductile fracture in Al alloys which widely used in\nmodern transportation industry. The atomic structure of the very tip of a crack\nfront has remained unknown, however. We have carried out a first-principles\ndensity functional theory study to reveal the precise alignment of atoms near\nthe crack tip in single-crystalline Al. The calculations demonstrate that the\nCTOA increases with the opening displacement, thus the observed constant CTOA\nin millimeter scale is an entirely plastic effect during ductile crack.\nBesides, we find no significant crack tunneling (crack-front blunting), which\ncan be accounted for from the very small relaxation of the Al free surface. The\natomic structure thus obtained provides a solid basis for larger scale\nsimulations using for example finite element method."
    },
    {
        "anchor": "Dynamic modulation of phonon-assisted transitions in quantum defects in\n  monolayer transition-metal dichalcogenide semiconductors: Quantum localization via atomic point defects in semiconductors is of\nsignificant fundamental and technological importance. Quantum defects in\nmonolayer transition-metal dichalcogenide semiconductors have been proposed as\nstable and scalable optically-addressable spin qubits. Yet, the impact of\nstrong spin-orbit coupling on their dynamical response, for example under\noptical excitation, has remained elusive. In this context, we study the effect\nof spin-orbit coupling on the electron-phonon interaction in a single chalcogen\nvacancy defect in monolayer transition metal dichalcogenides, molybdenum\ndisulfide (MoS$_2$) and tungsten disulfide (WS$_2$). From ab initio electronic\nstructure theory calculations, we find that spin-orbit interactions tune the\nmagnitude of the electron-phonon coupling in both optical and charge-state\ntransitions of the defect, modulating their respective efficiencies. This\nobservation opens up a promising scheme of dynamically modulating material\nproperties to tune the local behavior of a quantum defect.",
        "positive": "Enhanced Ferromagnetic Stability in Cu Doped Passivated GaN Nanowires: Density functional calculations are performed to investigate the room\ntemperature ferromagnetism in GaN:Cu nanowires (NWs). Our results indicate that\ntwo Cu dopants are most stable when they are near each other. Compared to bulk\nGaN:Cu, we find that magnetization and ferromagnetism in Cu doped NWs is\nstrongly enhanced because the band width of the Cu td band is reduced due to\nthe 1D nature of the NW. The surface passivation is shown to be crucial to\nsustain the ferromagnetism in GaN:Cu NWs. These findings are in good agreement\nwith experimental observations and indicate that ferromagnetism in this type of\nsystems can be tuned by controlling the size or shape of the host materials."
    },
    {
        "anchor": "On the structure of defects in the Fe7Mo6 $\u03bc$-Phase: Topologically close packed phases, among them the $\\mu$-phase studied here,\nare commonly considered as being hard and brittle due to their close packed and\ncomplex structure. Nanoindentation enables plastic deformation and therefore\ninvestigation of the structure of mobile defects in the $\\mu$-phase, which, in\ncontrast to grown-in defects, has not been examined yet. High resolution\ntransmission electron microscopy (HR-TEM) performed on samples deformed by\nnanoindentation revealed stacking faults which are likely induced by plastic\ndeformation. These defects were compared to theoretically possible stacking\nfaults within the $\\mu$-phase building blocks, and in particular Laves phase\nlayers. The experimentally observed stacking faults were found resulting from\nsynchroshear assumed to be associated with deformation in the Laves-phase\nbuilding blocks.",
        "positive": "Hole doping, hybridization gap, and electronic correlation in graphene\n  on a platinum substrate: The interaction between graphene and substrates provides a viable routes to\nenhance functionality of both materials. Depending on the nature of electronic\ninteraction at the interface, the electron band structure of graphene is\nstrongly influenced, allowing us to make use the intrinsic properties of\ngraphene or to design additional functionality in graphene. Here, we present an\nangle-resolved photoemission study on the interaction between graphene and a\nplatinum substrate. The formation of an interface between graphene and platinum\nleads to a strong deviation in the electronic structure of graphene not only\nfrom its freestanding form but also from the behavior observed on typical\nmetals. The combined study on the experimental and theoretical electron band\nstructure unveils the unique electronic properties of graphene on a platinum\nsubstrate, which singles out graphene/platinum as a model system investigating\ngraphene on a metallic substrate with strong interaction."
    },
    {
        "anchor": "Non-ferroelectric nature of the conductance hysteresis in CH3NH3PbI3\n  perovskite-based photovoltaic devices: We present measurements of conductance hysteresis on CH3NH3PbI3 perovskite\nthin films, performed using the double-wave method, in order to investigate the\npossibility of a ferroelectric response. A strong frequency dependence of the\nhysteresis is observed in the range of 0.1 Hz to 150 Hz, with a hysteretic\ncharge density in excess of 1000 {\\mu}C/cm2 at frequencies below 0.4 Hz - a\nbehaviour uncharacteristic of a ferroelectric response. We show that the\nobserved hysteretic conductance, as well as the presence of a double arc in the\nimpedance spectroscopy, can be fully explained by the migration of mobile ions\nunder bias on a timescale of seconds. Our measurements place an upper limit of\napproximately 1 {\\mu}C/cm2 on any intrinsic frequency-independent polarisation,\nruling out ferroelectricity as the main cause of current-voltage hysteresis and\nproviding further evidence of the importance of ionic migration in modifying\nthe efficiency of CH3NH3PbI3 devices.",
        "positive": "High-pressure structural phase transitions in CuWO4: We study the effects of pressure on the structural, vibrational, and magnetic\nbehavior of cuproscheelite. We performed powder x-ray diffraction and Raman\nspectroscopy experiments up to 27 GPa as well as ab initio total-energy and\nlattice-dynamics calculations. Experiments provide evidence that a structural\nphase transition takes place at 10 GPa from the low-pressure triclinic phase\n(P-1) to a monoclinic wolframite-type structure (P2/c). Calculations confirmed\nthis finding and indicate that the phase transformation involves a change in\nthe magnetic order. In addition, the equation of state for the triclinic phase\nis determined: V0 = 132.8(2) A3, B0 = 139 (6) GPa and = 4. Furthermore,\nexperiments under different stress conditions show that non-hydrostatic\nstresses induce a second phase transition at 17 GPa and reduce the\ncompressibility of CuWO4, B0 = 171(6) GPa. The pressure dependence of all Raman\nmodes of the triclinic and high-pressure phases is also reported and discussed."
    },
    {
        "anchor": "Electronic properties of atomically coherent square PbSe nanocrystal\n  superlattice resolved by STS: Rock-salt lead selenide nanocrystals can be used as building blocks for large\nscale square superlattices via two-dimensional assembly of nanocrystals at a\nliquid-air interface followed by oriented attachment. Here we report\nmeasurements of the local density of states of an atomically coherent\nsuperlattice with square geometry made from PbSe nanocrystals. Controlled\nannealing of the sample permits the imaging of a clean structure and to\nreproducibly probe the band gap and the valence hole and conduction electron\nstates. The measured band gap and peak positions are compared to the results of\noptical spectroscopy and atomistic tight-binding calculations of the square\nsuperlattice band structure. In spite of the crystalline connections between\nnanocrystals that induce significant electronic couplings, the electronic\nstructure of the superlattices remains very strongly influenced by the effects\nof disorder and variability.",
        "positive": "Agreement of classical Kubo theory with the infrared dispersion curves\n  $n(\u03c9)$ of ionic crystals: The theoretical dispersion curves $n(\\omega)$ (refractive index versus\nfrequency) of ionic crystals in the infrared domain are expressed, within the\nGreen--Kubo theory, in terms of a time correlation function involving the\nmotion of the ions only. The aim of this paper is to investigate how well the\nexperimental data are reproduced by a classical approximation of the theory, in\nwhich the time correlation functions are expressed in terms of the ions orbits.\nWe report the results of molecular dynamics (MD) simulations for the ions\nmotions of a LiF lattice of 4096 ions at room temperature. The theoretical\ncurves thus obtained are in surprisingly good agreement with the experimental\ndata, essentially over the whole infrared domain. This shows that at room\ntemperature the motion of the ions develops essentially in a classical regime."
    },
    {
        "anchor": "Polar optical phonon states and their dispersive spectra of a wurtzite\n  nitride superlattice with complex bases: transfer-matrix method: Based on the dielectric continuum model and transfer-matrix method, the\ncompleting polar optical phonon states in a wurtzite GaN-based superlattice\n(SLs) with arbitrary-layer complex bases are investigated. It is proved that\n$2^n$ types of phonon modes probably exist in a wurtzite nitride SL with\n$n$-layer complex bases. The analytical phonon states of these modes and their\ndispersive equations in the wurtzite GaN/Al$_{x}$Ga$_{1-x}$N SL structures are\nobtained. Numerical calculations on a three-layer\nGaN/Al$_{0.15}$Ga$_{0.85}$N/AlN complex bases SL are performed. Results reveal\nthat there are interface optical (IO) phonon modes of one type only and four\ntypes of quasi-confined (QC) phonon modes in three-layer\nGaN/Al$_{0.15}$Ga$_{0.85}$N/AlN complex bases SLs. The dispersive spectra of\nphonon modes in complex bases SLs extend to be a series of frequency bands. The\nbehaviors of QC modes reducing to IO modes are observed. The present\ntheoretical scheme and numerical results are quite useful for analyzing the\ndispersive spectra of completing phonon modes and their polaronic effect in\nwurtzite GaN-based SLs with complex bases.",
        "positive": "Inverse spin crossover in fluorinated\n  Fe(1,10-phenanthroline)$_2$(NCS)$_2$ adsorbed on Cu (001) surface: Density functional theory (DFT) including van der Waals weak interaction in\nconjunction with the so called rotational invariant DFT+U, where $U$ is the\nHubbard interaction of the iron site, is used to show that the fluorinated spin\ncrossover Fe(phen$)_{2}$(NCS$)_{2}$ molecule whether in the gas phase or\nadsorbed on Cu(001) surface switches from the original low spin state to the\nhigh spin state. Using Bader electron density analysis, this inversion of the\nspin-crossover is explained in terms of electron doping of the Fe-octahedron\ncage which led to an increase of the Fe-N bond lengths. Consequently, the\nligand-field splitting is drastically reduced, making the high-spin ground\nstate more stable than the low-spin state. The calculated scanning tunneling\nmicroscopy (STM) images in the Tersoff-Hamann approximation show a clear\ndistinction between the fluorinated and the unfluorinated molecule. This\ntheoretical prediction is awaiting future STM experimental confirmation."
    },
    {
        "anchor": "Quantum molecular dynamic simulations of warm dense carbon monoxide: Using quantum molecular dynamic simulations, we have studied the\nthermophysical properties of warm dense carbon monoxide under extreme\nconditions. The principal Hugoniot, which is derived from the equation of\nstate, shows excellent agreement with available experimental data up to 67 GPa.\nThe chemical decomposition of carbon monoxide has been predicted at 8 GPa by\nmeans of pair correlation function. Based on Kubo-Greenwood formula, the dc\nelectrical conductivity and the optical reflectivity are determined, and the\nnonmetal-metal transition for shock compressed carbon monoxide is observed\naround 43 GPa.",
        "positive": "Effect of doping-- and field--induced charge carrier density on the\n  electron transport in nanocrystalline ZnO: Charge transport properties of thin films of sol--gel processed undoped and\nAl-doped zinc oxide nanoparticles with variable doping level between 0.8 at%\nand 10 at% were investigated. The X-ray diffraction studies revealed a decrease\nof the average crystallite sizes in highly doped samples. We provide estimates\nof the conductivity and the resulting charge carrier densities with respect to\nthe doping level. The increase of charge carrier density due to extrinsic\ndoping were compared to the accumulation of charge carriers in field effect\ntransistor structures. This allowed to assess the scattering effects due to\nextrinsic doping on the electron mobility. The latter decreases from 4.6*10^-3\ncm^2/Vs to 4.5*10^-4 cm^2/Vs with increasing doping density. In contrast, the\naccumulation leads to an increasing mobility up to 1.5*10^-2 cm^2/Vs. The\npotential barrier heights related to grain boundaries between the crystallites\nwere derived from temperature dependent mobility measurements. The extrinsic\ndoping initially leads to a grain boundary barrier height lowering, followed by\nan increase due to doping-induced structural defects. We conclude that the\nconductivity of sol--gel processed nanocrystalline ZnO:Al is governed by an\ninterplay of the enhanced charge carrier density and the doping-induced charge\ncarrier scattering effects, achieving a maximum at 0.8 at% in our case."
    },
    {
        "anchor": "On the microscopic mechanisms behind hyperferroelectricity: Hyperferroelectrics are receiving a growing interest thanks to their unique\nproperty to retain a spontaneous polarization even in presence of a\ndepolarizing field. Nevertheless, general microscopic mechanisms driving\nhyperferroelectricity, which is ascribed to the softening of a polar $LO$ mode,\nare still missing. Here, by means of phonons calculations and force constants\nanalysis in two class of hyperferroelectrics, the ABO$_3$-LiNbO3-type systems\nand the prototypical hexagonal-ABC systems, we unveiled common features in the\ndynamical properties of a hyperferroelectric behind such $LO$ instability:\nnegative or vanishing on-site force constant associated to the cation driving\nthe $LO$ polar distortion, and destabilizing cation-anion interactions, both\ninduced by short-range forces. We also predict possible enhancement of the\nhyperferroelectric properties by applying an external positive pressure;\npressure strengthens the destabilizing short-range interactions. Particularly,\nthe increase in the mode effective charges associated to the unstable $LO$ mode\nunder pressure suggests an eventual enhancement of the $D$=0 polarization under\ncompressive strain.",
        "positive": "Enhanced grain surface effect on magnetic properties of nanometric\n  La0.7Ca0.3MnO3 manganite : Evidence of surface spin freezing of manganite\n  nanoparticles: We have investigated the effect of nanometric grain size on magnetic\nproperties of single phase, nanocrystalline, granular La0.7Ca0.3MnO3 (LCMO)\nsample. We have considered core-shell structure of our LCMO nanoparticles,\nwhich can explain its magnetic properties. From the temperature dependence of\nfield cooled (FC) and zero-field cooled (ZFC) dc magnetization (DCM), the\nmagnetic properties could be distinguished into two regimes: a relatively high\ntemperature regime T > 40 K where the broad maximum of ZFC curve (at T = Tmax)\nis associated with the blocking of core particle moments, whereas the sharp\nmaximum (at T = TS) is related to the freezing of surface (shell) spins. The\nunusual shape of M (H) loop at T = 1.5 K, temperature dependent feature of\ncoercive field and remanent magnetization give a strong support of surface spin\nfreezing that are occurring at lower temperature regime (T < 40 K) in this LCMO\nnanoparticles. Additionally, waiting time (tw) dependence of ZFC relaxation\nmeasurements at T = 50 K show weak dependence of relaxation rate [S(t)] on tw\nand dM/dln(t) following a logarithmic variation on time. Both of these features\nstrongly support the high temperature regime to be associated with the blocking\nof core moments. At T = 20 K, ZFC relaxation measurements indicates the\nexistence of two different types of relaxation processes in the sample with\nS(t) attaining a maximum at the elapsed time very close to the wait time tw =\n1000 sec, which is an unequivocal sign of glassy behavior. This age-dependent\neffect convincingly establish the surface spin freezing of our LCMO\nnanoparticles associated with a background of superparamagnetic (SPM) phase of\ncore moments."
    },
    {
        "anchor": "An AsFem implementation for quasi-static brittle fracture phase field\n  model: Phase field method has been widely used because of its excellent ability to\nsimulate fracture problems. At present, the implementation process is mainly\nbased on commercial software, and the operation process is relatively complex.\nIn this paper, 2D and 3D phase field models are implemented in the open-source\nfinite element software package AsFem. Compared with commercial software, it is\nsimpler to realize phase field fracture model in AsFem. At the same time, a\nrobust staggered scheme and an efficient monolithic scheme can be used to solve\nthe displacement field and phase field sub-problem, and the transformation\nprocess is very easy. Several examples are tested to demonstrate the\nperformance of the current implementation. The simulation results are in good\nagreement with the previous work, which shows the feasibility and effectiveness\nof implementing the phase field method in AsFem. In the future, more complex\nmulti-field coupled phase field fracture problems can be solved with AsFem.",
        "positive": "Localized tip enhanced Raman spectroscopic study of impurity\n  incorporated single GaN nanowire in the sub-diffraction limit: The localized effect of impurities in single GaN nanowires in the\nsub-diffraction limit is reported using the study of lattice vibrational modes\nin the evanescent field of Au nanoparticle assisted tip enhanced Raman\nspectroscopy (TERS). GaN nanowires with the O impurity and the Mg dopants were\ngrown by the chemical vapor deposition technique in the catalyst assisted\nvapor-liquid-solid process. Symmetry allowed Raman modes of wurtzite GaN are\nobserved for undoped and doped nanowires. Unusually very strong intensity of\nthe non-zone center zone boundary mode is observed for the TERS studies of both\nthe undoped and the Mg doped GaN single nanowires. Surface optical mode of A1\nsymmetry is also observed for both the undoped and the Mg doped GaN samples. A\nstrong coupling of longitudinal optical (LO) phonons with free electrons,\nhowever is reported only in the O rich single nanowires with the asymmetric\nA1(LO) mode. Study of the local vibration mode shows the presence of Mg as\ndopant in the single GaN nanowires."
    },
    {
        "anchor": "Correlation-enhanced spin-orbit coupling and quantum anomalous Hall\n  insulator with large band gap and stable ferromagnetism in monolayer\n  $\\mathrm{Fe_2Br_2}$: Nontrivial band topology combined with magnetic ordering can produce quantum\nanomalous Hall insulator (QAHI), which may lead to advances in device concepts.\nHere, through first-principles calculations, stable monolayer\n$\\mathrm{Fe_2Br_2}$ is predicted as a room-temperature large-gap\nhigh-Chern-number QAHI by using generalized gradient approximation plus $U$\n(GGA+$U$) approach. The large gap is due to correlation-enhanced spin-orbit\ncoupling (SOC) effect of Fe atoms, which equates with artificially increasing\nthe strength of SOC without electronic correlation. Out-of-plane magnetic\nanisotropy is very key to produce quantum anomalous Hall (QAH) state because\nin-plane magneitization will destroy nontrivial band topology. In the absence\nof SOC, $\\mathrm{Fe_2Br_2}$ is a half Dirac semimetal state protected by mirror\nsymmetry, and the electronic correlation along with SOC effect creates QAH\nstate with a sizable gap and two chiral edge modes. It is found that the QAH\nstate is robust against biaxial strain ($a/a_0$: 0.96 to 1.04) in monolayer\n$\\mathrm{Fe_2Br_2}$ with stable ferromagnetic (FM) ordering and out-of-plane\nmagnetic anisotropy. Calculated results show that Curie temperature is\nsensitive to correlation strength and strain. The reduced correlation and\ncompressive strain are in favour of high Curie temperature. These analysis and\nresults can be readily extended to other monolayer $\\mathrm{Fe_2XY}$ (X/Y=Cl,\nBr and I), which possesses the same Fe-dominated low-energy states with a\n$\\mathrm{Fe_2Br_2}$ monolayer. These findings open new opportunities to design\nnew high-temperature topological quantum devices.",
        "positive": "Theory of surface plasmons and surface-plasmon polaritons: Collective electronic excitations at metal surfaces are well known to play a\nkey role in a wide spectrum of science, ranging from physics and materials\nscience to biology. Here we focus on a theoretical description of the many-body\ndynamical electronic response of solids, which underlines the existence of\nvarious collective electronic excitations at metal surfaces, such as the\nconventional surface plasmon, multipole plasmons, and the recently predicted\nacoustic surface plasmon. We also review existing calculations, experimental\nmeasurements, and applications."
    },
    {
        "anchor": "Lack of simple correlation between switching current density and\n  spin-orbit torque efficiency of perpendicularly magnetized spin-current\n  generator/ferromagnet heterostructures: Spin-orbit torque can drive electrical switching of magnetic layers. Here, we\nreport that at least for micrometer-sized samples there is no simple\ncorrelation between the efficiency of dampinglike spin-orbit torque\n({\\xi}_DL^j) and the critical switching current density of perpendicularly\nmagnetized spin-current generator/ferromagnet heterostructures. We find that\nthe values of {\\xi}_DL^j based on switching current densities can either under-\nor over-estimated {\\xi}_DL^j by up to tens of times in a domain-wall depinning\nanalysis, while in the macrospin analysis based on the switching current\ndensity {\\xi}_DL^j can be overestimated by up to thousands of times. When\ncomparing the relative strengths of {\\xi}_DL^j of spin-current generators, the\ncritical switching current densities by themselves are a poor predictor.",
        "positive": "Ideas of lattice-basis reduction theory for error-stable Bravais lattice\n  determination and ab-initio indexing: Although newly developed indexing software is frequently reported in\ncrystallography, it is not widely recognized that the use of error-stable\nBravais lattice determinations can simplify indexing algorithms and increase\ntheir success rates. In indexing, a code for error-stable unit-cell\nidentification is also required to exclude duplicate solutions. One of our\ngoals is to collect information on the lattice-basis reduction theory and its\napplication to these analyses.\n  The main result is an error-stable Bravais lattice determination algorithm\nfor 2D lattices, along with a mathematical proof that it works even for\nparameters containing large observational errors. As in our algorithm for 3D\nlattices, it uses two lattice-basis reduction methods that seem to be optimal\nfor different symmetries.\n  As another application of lattice-basis reduction theory to the unit-cell\nidentification, we introduce several methods to measure the difference of unit\ncells known in crystallography and mathematics."
    },
    {
        "anchor": "Buffer-layer-controlled Nickeline vs Zinc-Blende/Wurtzite-type MnTe\n  growths on c-plane Al2O3 substrates: In the recent past, MnTe has proven to be a crucial component of the\nintrinsic magnetic topological insulator (IMTI) family [MnTe]m[Bi2Te3]n, which\nhosts a wide range of magneto-topological properties depending on the choice of\nm and n. However, bulk crystal growth allows only a few combinations of m and n\nfor these IMTIs due to the strict limitations of the thermodynamic growth\nconditions. One way to overcome this challenge is to utilize atomic\nlayer-by-layer molecular beam epitaxy (MBE) technique, which allows arbitrary\nsequences of [MnTe]m and [Bi2Te3]n to be formed beyond the thermodynamic limit.\nFor such MBE growth, finding optimal growth templates and conditions for the\nparent building block, MnTe, is a key requirement. Here, we report that two\ndifferent hexagonal phases of MnTe-nickeline (NC) and zinc-blende/wurtzite\n(ZB-WZ) structures, with distinct in-plane lattice constants of 4.20 +/- 0.04 A\nand 4.39 +/- 0.04 A, respectively-can be selectively grown on c-plane Al2O3\nsubstrates using different buffer layers and growth temperatures. Moreover, we\nprovide the first comparative studies of different MnTe phases using\natomic-resolution scanning transmission electron microscopy and show that ZB\nand WZ-like stacking sequences can easily alternate between the two.\nSurprisingly, In2Se3 buffer layer, despite its lattice constant (4.02 A) being\ncloser to that of the NC phase, fosters the ZB-WZ instead, whereas Bi2Te3,\nsharing the same lattice constant (4.39 A) with the ZB-WZ phase, fosters the NC\nphase. These discoveries suggest that lattice matching is not always the most\ncritical factor determining the preferred phase during epitaxial growth.\nOverall, this will deepen our understanding of epitaxial growth modes for\nchalcogenide materials and accelerate progress toward new IMTI phases as well\nas other magneto-topological applications.",
        "positive": "Magnetization Characteristic of Ferromagnetic Thin Strip by Measuring\n  Anisotropic Magnetoresistance and Ferromagnetic Resonance: The magnetization characteristic in a permalloy thin strip is investigated by\nelectrically measuring the anisotropic magnetoresistance and ferromagnetic\nresonance in in-plane and out-of-plane configurations. Our results indicate\nthat the magnetization vector can rotate in the film plane as well as out of\nthe film plane by changing the intensity of external magnetic field of certain\ndirection. The magnetization characteristic can be explained by considering\ndemagnetization and magnetic anisotropy. Our method can be used to obtain the\ndemagnetization factor, saturated magnetic moment and the magnetic anisotropy."
    },
    {
        "anchor": "First-principles thermoelasticity of bcc iron under pressure: We investigate the elastic and isotropic aggregate properties of\nferromagnetic bcc iron as a function of temperature and pressure by computing\nthe Helmholtz free energies for the volume-conserving strained structures using\nthe first-principles linear response linear-muffin-tin-orbital method and the\ngeneralized-gradient approximation. We include the electronic excitation\ncontributions to the free energy from the band structures, and phonon\ncontributions from quasi-harmonic lattice dynamics. We make detailed\ncomparisons between our calculated elastic moduli and their temperature and\npressure dependences with available experimental and theoretical data.",
        "positive": "Effect of Anchoring Groups on the Conduction Properties of Phenyl Based\n  on Organic Molecules Connected to Copper Leads: We report equilibrium and non-equilibrium conductance of terphenyl molecules\nwith different anchoring groups including sulfur and nitrogen atom. The\ncorresponding molecules are terphenyl-dithiols(TPDT) and\ndiamino-terphenyl(DATP). The non-equilibrium Green's function (NEGF) technique\nhas been implemented on the density functional tight-binding (DFTB) code to\nperform computations of the electronic transport properties of molecular\ndevices. The NEGFs are used to compute the electronic density self-consistently\nwith open boundary condition naturally encountered in transport problem which\nis imposed by the potentials at the contacts. As result, the value of the\nmolecular conductance with amine groups is higher about ten times than the\nthiol anchored group"
    },
    {
        "anchor": "Rational Design of Molybdenum Transition-Metal subnanoclusters catalysts\n  with Particle Swarm Optimization: The development of novel sub-nanometer clusters (SNCs) catalysts with\nsuperior catalytic performance depends on the precise control of clusters'\natomistic sizes, shapes, and accurate deposition onto surfaces. Recent\nadvancements in manufacturing and characterization techniques have paved the\nway for the production and atomic resolution characterization of\ntransition-metal SNCs catalysts, positioning them as a promising new class of\nmaterials for this application. Nevertheless, the intrinsic complexity of the\nadsorption process complicates the ability to achieve an atomistic\nunderstanding of the most relevant structure-reactivity relationships hampering\nthe rational design of novel catalytic materials. In most cases, existing\ncomputational approaches rely on just a few structures to conclude clusters'\nreactivity thereby neglecting the complexity of the existing energy landscapes\nthus leading to insufficient sampling and, most likely, unreliable predictions.\nMoreover, modelling of the actual experimental procedure that is responsible\nfor the deposition of SNCs on surfaces is often not done even though in some\ncases this procedure may enhance the significance of certain (e.g., metastable)\nadsorption geometries. This study proposes a novel approach that utilizes\nparticle swarm optimization (PSO) method, in conjunction with ab-initio\ncalculations, to predict the most relevant SNCs structures on a surface in beam\nexperiments, and consequently their reactivity. To illustrate the main steps of\nour approach, we consider the deposition of Molybdenum SNC of 6 Mo atoms on a\nfree-standing graphene surface, as well as their catalytic properties\nconcerning the CO molecule dissociation reaction. This study demonstrates the\nfeasibility of the PSO technique for studying catalyst transition-metal SNCs\nand establishes a reliable procedure for performing theoretical rational design\npredictions.",
        "positive": "Effects of Rate, Size and Prior Deformation in Microcrystal Plasticity: Crystal plasticity of sub-micron finite volumes is characterized by the flow\nof emergent dislocation defects, giving rise to size effects in mechanical\nproperties and avalanche phenomena. In this chapter, we present a minimal model\nfor discrete edge dislocations in a finite volume, that has been benchmarked\nagainst experimental data and displays known phenomenological trends. We\ndiscuss how this model can explain seemingly disconnected effects of rate, size\nand prior deformation on microcrystal plasticity. We demonstrate the\nstatistical features of dislocation ensembles for both stress and displacement\ncontrolled loading conditions and explore in detail the connection between\nloading rate and displacement bursts. Finally, we present model studies of\nmachine learning algorithms in microcrystal plasticity that both improve\nunderstanding and clarify the range of such methods' usefulness. In this way,\nwe elucidate the role of prior deformation history on micro and nano-sized\nspecimens and we use this understanding to predict the mechanical response of\nthin films through microstructural observations of pre-existing dislocation\nconfigurations."
    },
    {
        "anchor": "Integration of external electric fields in molecular dynamics simulation\n  models for resistive switching devices: Resistive switching devices emerged a huge amount of interest as promising\ncandidates for non-volatile memories as well as artificial synapses due to\ntheir memristive behavior. The main physical and chemical phenomena which\ndefine their functionality are driven by externally applied voltages, and the\nresulting electric fields. Although molecular dynamics simulations are widely\nused in order to describe the dynamics on the corresponding atomic length and\ntime scales, there is a lack of models which allow for the actual driving force\nof the dynamics, i.e. externally applied electric fields. This is due to the\nrestriction of currently applied models to either solely conductive,\nnon-reactive or insulating materials, with thicknesses in the order of the\npotential cutoff radius, i.e., 10 \\r{A}. In this work, we propose a generic\nmodel, which can be applied in particular to describe the resistive switching\nphenomena of metal-insulator-metal systems. It has been shown that the\ncalculated electric field and force distribution in case of the chosen example\nsystem Cu/a-SiO$_2$/Cu are in agreement with fundamental field theoretical\nexpectations.",
        "positive": "High-throughput search for triplet point defects with narrow emission\n  lines in 2D materials: We employ a first-principles computational workflow to screen for optically\naccessible, high-spin point defects in wide band gap two-dimensional (2D)\ncrystals. Starting from an initial set of 5388 point defects, comprising both\nintrinsic and extrinsic, single and double defects in ten previously\nsynthesised 2D host materials, we identify 596 defects with a triplet ground\nstate. For these defects, we calculate the defect formation energy, the\nhyperfine (HF) coupling, and the zero-field splitting (ZFS) tensors. For 39\ntriplet transitions exhibiting particularly low Huang-Rhys factors, we\ncalculate the full photo-luminescence (PL) spectrum. Our approach reveals many\nnew spin defects with narrow PL line shapes and emission frequencies covering a\nbroad spectral range. Most of the defects are hosted in hexagonal BN, which we\nascribe to its high stiffness, but some are also found in MgI2, MoS2, MgBr2 and\nCaI2. As specific examples, we propose the defects vSMoS0 and NiSMoS0 in MoS2\nas interesting candidates with potential applications to magnetic field sensors\nand quantum information technology. All the data will be made available in the\nopen access database QPOD."
    },
    {
        "anchor": "Cerium as a possible stabilizer of ThMn$_{12}$-type iron-based\n  compounds: A first-principles study: The structural stability of CeFe$_{12}$ is investigated by using\nfirst-principles calculation. The formation energies of CeFe$_{12}$ relative to\nthe Ce$_{2}$Fe$_{17}$ + bcc-Fe phase and to the CeFe$_{2}$ + bcc-Fe phase are\ncalculated with the assumptions of trivalency and tetravalency for Ce. Those\nvalues are compared with corresponding results in $R$Fe$_{12}$ for $R=$ Nd, Sm,\nand Zr. Our results suggest that the tetravalent Ce is a promising stabilizer\nof the ThMn$_{12}$ structure. We also show that the stabilizing effect of an\nelement depends as much on the valency as on the size of the $R$ element by\ninvestigating $R$Fe$_{12}$ where $R$ is assumed to have a hypothetical valency\non the basis of first-principles calculation.",
        "positive": "Charge-driven transtive devices via electric field control of magnetism\n  in a helimagnet: Transtor and memtranstor are the fourth basic linear and memory elements,\nwhich allows direct coupling of charge (q) to magnetic flux ({\\phi}) via linear\nand non-linear ME effects, respectively. It is found here that large variation\nof magnetization by electric field is realized in both linear and nonlinear\nhysteretic styles in a magnetoelectric Y-type hexaferrite\nBa0.5Sr1.5Zn2(Fe0.92Al0.08)12O22 single-crystal. Moreover, based on the spin\ncurrent model, the underlying microscopic mechanisms for generating the two\ntypes of linear and nonlinear M vs E curves are understood as E induced changes\nof cone angle and sign of P respectively, establishing the charge-driven\ntranstor and memtranstor in the Y-type hexaferrite system. This work points to\na promising pathway to develop unique circuit functionalities using the\nmagnetoelectric materials."
    },
    {
        "anchor": "Detection of charge density wave phase transitions at 1T-TaS$_2$/GaAs\n  interfaces: The transition metal dichalcogenide 1T-TaS$_2$ is well known to harbor a rich\nvariety of charge density wave (CDW) distortions which are correlated with\nunderlying lattice atom modulations. The long range CDW phases extend\nthroughout the whole crystal and terminate with charge displacements at the\ncrystal boundaries. Here we report on the transport properties and capacitance\ncharacteristics of the interface between freshly exfoliated flakes of\n1T-TaS$_2$ in intimate van der Waals contact with \\textit{n}-type GaAs\nsubstrates. The extracted barrier parameters (ideality, barrier height and\nbuilt-in potential) experience pronounced changes across the Mott-CDW\ntransition in the 1T-TaS$_2$. The CDW-induced changes in barrier properties are\nwell described by a bond polarization model which upon decreasing temperature\ngives rise to an increased potential drop across the interfacial region due to\nthe localization of carriers and a decreased dielectric constant.",
        "positive": "Enhanced Electron Extraction in Co-Doped TiO2 Quantified by\n  Drift-Diffusion Simulation for Stable CsPbI3 Solar Cells: Solar cells based on inorganic perovskite CsPbI3 are promising candidates to\nresolve the challenge of operational stability in the field of perovskite\nphotovoltaics. For stable operation, however, it is crucial to thoroughly\nunderstand the extractive and recombinative processes occurring at the\ninterfaces of perovskite and the charge-selective layers. In this study, we\nfocus on the electronic properties of (doped) TiO2 as an electron-selective\ncontact. We show via KPFM that co-doping of TiO2 with Nb(V) and Sn(IV) reduces\nthe materials work function by 270 meV, giving it stronger n-type\ncharacteristics compared to Nb(V) mono-doped TiO2. The altered electronic\nalignment with CsPbI3 translates to enhanced electron extraction, as\ndemonstrated with ssPL, trPL and trSPV in triad. Importantly, we extract\ncrucial parameters, such as the concentration of extracted electrons and the\ninterface hole recombination velocity, from the SPV transients via 2D\ndrift-diffusion simulations. When implementing the co-doped TiO2 into full\nn-i-p solar cells, the operational stability is enhanced to 32000 h of\nprojected TS80 lifetime. This study provides fundamental understanding of\ninterfacial charge extraction and its correlation with operational stability of\nperovskite solar cells, which can be transferred to other charge-selective\ncontacts."
    },
    {
        "anchor": "Transparent and conductive graphene oxide-polyethylenglycol diacrylate\n  coatings obtained by photopolymerization: Water dispersed graphene oxide sheets were used to prepare\ngraphene-polyethylenglycol diacrylate resin composites by photopolymerization.\nIt was found that graphene sheets undergo excellent morphological distribution\nwithin the resin system, giving rise to transparent composites with unaltered\nthermal properties with respect to the neat resin, that are electrically\nconductive at loading ratios as low as 0.02 %wt of graphene oxide . The\nproposed strategy based on photopolymerization provides an easy, energy-saving\nand environmental friendly technique that can find a wide application in\ncoating technology, mainly for electromagnetic shielding and antistatic\ncoatings.",
        "positive": "Edge Effects in Finite Elongated Graphene Nanoribbons: We analyze the relevance of finite-size effects to the electronic structure\nof long graphene nanoribbons using a divide and conquer density functional\napproach. We find that for hydrogen terminated graphene nanoribbons most of the\nphysical features appearing in the density of states of an infinite graphene\nnanoribbon are recovered at a length of 40 nm. Nevertheless, even for the\nlongest systems considered (72 nm long) pronounced edge effects appear in the\nvicinity of the Fermi energy. The weight of these edge states scales inversely\nwith the length of the ribbon and they are expected to become negligible only\nat ribbons lengths of the order of micrometers. Our results indicate that\ncareful consideration of finite-size and edge effects should be applied when\ndesigning new nanoelectronic devices based on graphene nanoribbons. These\nconclusions are expected to hold for other one-dimensional systems such as\ncarbon nanotubes, conducting polymers, and DNA molecules."
    },
    {
        "anchor": "Interaction of W(CO)$_6$ with SiO$_2$ Surfaces -- A Density Functional\n  Study: The interaction of tungsten hexacarbonyl W(CO)$_6$ precursor molecules with\nSiO$_2$ substrates is investigated by means of density functional theory\ncalculations with and without inclusion of long range van der Waals\ninteractions. We consider two different surface models, a fully hydroxylated\nand a partially hydroxylated SiO$_2$ surface, corresponding to substrates under\ndifferent experimental conditions. For the fully hydroxylated surface we\nobserve only a weak interaction between the precursor molecule and the\nsubstrate with physisorption of W(CO)$_6$. Inclusion of van der Waals\ncorrections results in a stabilization of the molecules on this surface, but\ndoes not lead to significant changes in the chemical bonding. In contrast, we\nfind a spontaneous dissociation of the precursor molecule on the partially\nhydroxylated SiO$_2$ surface where chemisorption of a W(CO)$_5$ fragment is\nobserved upon removal of one of the CO ligands from the precursor molecule.\nIrrespective of the hydroxylation, the precursor molecule prefers binding of\nmore than one of its CO ligands. In the light of these results, implications\nfor the initial growth stage of tungsten nano-deposits on SiO$_2$ in an\nelectron beam induced deposition process are discussed.",
        "positive": "Photochemical reaction on graphene surfaces controlled by\n  substrate-surface modification with polar self-assembled monolayers: The unique thinness of two-dimensional materials enables control over\nchemical phenomena at their surfaces by means of various gating techniques. For\nexample, gating methods based on field-effect-transistor configurations have\nbeen achieved. Here, we report a molecular gating approach that employs a local\nelectric field generated by a polar self-assembled monolayer formed on a\nsupporting substrate. By performing Raman scattering spectroscopy analyses with\na proper data correction procedure, we found that molecular gating is effective\nfor controlling solid phase photochemical reactions of graphene with benzoyl\nperoxide. Molecular gating offers a simple method to control chemical reactions\non the surfaces of two-dimensional materials because it requires neither the\nfabrication of a transistor structure nor the application of an external\nvoltage."
    },
    {
        "anchor": "Dual behavior of excess electrons in rutile TiO2: The behavior of electrons in the conduction band of TiO2 and other\ntransition-metal oxides is key to the many applications of these materials.\nExperiments seem to produce conflicting results: optical and spin-resonance\ntechniques reveal strongly localized small polarons, while electrical\nmeasurements show high mobilities that can only be explained by delocalized\nfree electrons. By means of hybrid functional calculations we resolve this\napparent contradiction and show that small polarons can actually coexist with\ndelocalized electrons in the conduction band of TiO2, the former being\nenergetically only slightly more favorable. We also find that small polarons\ncan form complexes with oxygen vacancies and ionized shallow-donor impurities,\nexplaining the rich spectrum of Ti$^{3+}$ species observed in electron spin\nresonance experiments.",
        "positive": "Viscoelastic Constitutive Artificial Neural Networks (vCANNs) $-$ a\n  framework for data-driven anisotropic nonlinear finite viscoelasticity: The constitutive behavior of polymeric materials is often modeled by finite\nlinear viscoelastic (FLV) or quasi-linear viscoelastic (QLV) models. These\npopular models are simplifications that typically cannot accurately capture the\nnonlinear viscoelastic behavior of materials. For example, the success of\nattempts to capture strain rate-dependent behavior has been limited so far. To\novercome this problem, we introduce viscoelastic Constitutive Artificial Neural\nNetworks (vCANNs), a novel physics-informed machine learning framework for\nanisotropic nonlinear viscoelasticity at finite strains. vCANNs rely on the\nconcept of generalized Maxwell models enhanced with nonlinear strain\n(rate)-dependent properties represented by neural networks. The flexibility of\nvCANNs enables them to automatically identify accurate and sparse constitutive\nmodels of a broad range of materials. To test vCANNs, we trained them on\nstress-strain data from Polyvinyl Butyral, the electro-active polymers VHB 4910\nand 4905, and a biological tissue, the rectus abdominis muscle. Different\nloading conditions were considered, including relaxation tests, cyclic\ntension-compression tests, and blast loads. We demonstrate that vCANNs can\nlearn to capture the behavior of all these materials accurately and\ncomputationally efficiently without human guidance."
    },
    {
        "anchor": "Glass engineering to enhance Si solar cells: a case study of\n  Pr$^{3+}$-Yb$^{3+}$ codoped tellurite-tungstate as spectral converter: Spectral converters are known to increase photovoltaic energy conversion by\nminimizing losses due to fundamental non-absorption and thermalization\nprocesses, and have been suggested to surpass the Shockley-Queisser efficiency\nlimit in single junction solar cells. Here we present a detailed spectroscopic\nstudy of photoluminescence in tellurite-tungstate glasses doped and codoped\nwith $Pr^{3+}-Yb^{3+}$ and $Ag$ nanoparticles. The energy transfer mechanisms\nbetween $Pr^{3+}$ and $Yb^{3+}$ are discussed based on the near infrared\nemission under excitation at $442$ nm and on the upconversion emission under\nexcitation at $980$ nm. Fluorescence quenching of $^2 F_{5/2}$ level of\n$Yb^{3+}$ is observed by increasing the concentration of $Pr^{3+}$, as well as\nby the addition of $Ag$ nanoparticles. In addition, a discussion on the\npotential of this glass to increase energy production in spectral converters is\npresented. The results suggest that the few undesirable energy transfer\nprocesses occurring in this material are difficult to be controlled or\neliminated properly, resulting in intrinsic losses. This discussion is extended\nto the potential of glass science to enhance energy production in solar cells,\nshowing that newer designs such as bifacial cells may facilitate the\nexploration of glasses other than soda-lime for mass production of solar cells.\nThe focus on extending the lifespan by reducing UV induced degradation seems to\nbe a more effective approach than the development of spectral converters for Si\nsolar cells.",
        "positive": "Classical and quantum ordering of protons in cold solid hydrogen under\n  megabar pressures: A combination of state-of-the-art theoretical methods has been used to obtain\nan atomic-level picture of classical and quantum ordering of protons in cold\nhigh-pressure solid hydro-gen. We focus mostly on phases II and III of\nhydrogen, exploring the effects of quantum nuclear motion on certain features\nof these phases (through a number of ab initio path-integral molecular dynamics\n(PIMD) simulations at particular points on the phase diagram). We also examine\nthe importance of van der Waals forces in this system by performing\ncalculations using the optB88-vdW density functional, which accounts for\nnon-local correlations. Our calculations reveal that the transition between\nphases I and II is strongly quantum in nature, resulting from a competition\nbetween anisotropic inter-molecular interactions that restrict molecular\nrotation and thermal plus quantum fluctuations of the nuclear positions that\nfacilitate it. The transition from phase II to III is more classical because\nquantum nuclear motion plays only a secondary role and the transition is\ndetermined primarily by the underlying potential energy surface. A structure of\nP21c symmetry with 24 atoms in the primitive unit cell is found to be stable\nwhen anharmonic quantum nuclear vibrational motion is included at finite\ntemperatures using the PIMD method. This structure gives a good account of the\ninfra-red (IR) and Raman vibron frequencies of phase II. We find ad-ditional\nsupport for C2/c structure as a strong candidate for phase III, since it\nremains transparent up to 300 GPa, even when quantum nuclear effects are\nincluded. Finally, we find that accounting for van der Waals forces improves\nthe agreement between experiment and theory for the parts of the phase diagram\nconsidered, when compared to previous work which employed the widely-used\nPerdew-Burke-Ernzerhof (PBE) exchange-correlation functional."
    },
    {
        "anchor": "Electronic and phonon contributions to the Thermoelectric properties of\n  newly discovered half-Heusler alloys XHfPb (X= Ni, Pd, and Pt): In this work we calculate the thermoelectric figure of merit of XHfPb (X= Ni,\nPd, and Pt) by computing the both the power factor and the lattice thermal\nconductivity by first principles. We make reasonable approximations: we use the\nConstant Relaxation Time Approximation (CRTA) to compute the electron transport\ncontribution and the modified Debye-Callaway model to calculate the thermal\nlattice conductivity. We also report the dielectric properties of these\nsemiconductors and the mode Gr\\\"uneisen parameters. Not surprisingly we find\nthat the average Gr\\\"uneisen coefficient correlates with the tehrmal\nconductivity. Next, we consider a realistic relaxation time $\\tau$ and carrier\nconcentration $n$ from experimental data on ZrHfPb and obtain the figure of\nmerit $ZT$ as a function of temperature. Our main finding is that despite the\nPt is isoelectronic with Ni and Pd, the $ZT$ of PtHfPb is larger and behaves\ndifferently from the other two materials, suggesting that PtHfPb is better\nsuited for high temperature thermoelectric generators.",
        "positive": "Optical Absorption Characteristics of Silicon Nanowires for Photovoltaic\n  Applications: Solar cells have generated a lot of interest as a potential source of clean\nrenewable energy for the future. However a big bottleneck in wide scale\ndeployment of these energy sources remain the low efficiency of these\nconversion devices. Recently the use of nanostructures and the strategy of\nquantum confinement have been as a general approach towards better charge\ncarrier generation and capture. In this article we have presented calculations\non the optical characteristics of nanowires made out of Silicon. Our\ncalculations show these nanowires form excellent optoelectronic materials and\nmay yield efficient photovoltaic devices."
    },
    {
        "anchor": "Automated Real-Space Lattice Extraction for Atomic Force Microscopy\n  Images: Analyzing atomically resolved images is a time-consuming process requiring\nsolid experience and substantial human intervention. In addition, the acquired\nimages contain a large amount of information such as crystal structure,\npresence and distribution of defects, and formation of domains, which need to\nbe resolved to understand a material's surface structure. Therefore, machine\nlearning techniques have been applied in scanning probe and electron\nmicroscopies during the last years, aiming for automatized and efficient image\nanalysis. This work introduces a free and open source tool (AiSurf: Automated\nIdentification of Surface Images) developed to inspect atomically resolved\nimages via Scale-Invariant Feature Transform (SIFT) and Clustering Algorithms\n(CA). AiSurf extracts primitive lattice vectors, unit cells, and structural\ndistortions from the original image, with no pre-assumption on the lattice and\nminimal user intervention. The method is applied to various atomically resolved\nnon-contact atomic force microscopy (AFM) images of selected surfaces with\ndifferent levels of complexity: anatase TiO2(101), oxygen deficient rutile\nTiO2(110) with and without CO adsorbates, SrTiO3(001) with Sr vacancies and\ngraphene with C vacancies. The code delivers excellent results and has proved\nto be robust against atom misclassification and noise, thereby facilitating the\ninterpretation scanning probe microscopy images.",
        "positive": "Electronic structure of a graphene superlattice with a modulated Fermi\n  velocity: The electronic structure of a graphene superlattice composed by two periodic\nregions with different Fermi velocity, energy gap and electrostatic potential\nis investigated by using an effective Dirac-like Hamiltonian. It must be\nexpected that the change of the Fermi velocity in one region of the graphene\nsuperlattice is equivalent to changing the width of this region keeping the\nFermi velocity unchanged, provided that the time taken to charge carriers cross\nthe region is the same. However, it is shown here that these two systems are\nnot equivalent. We found extra Dirac points induced by the periodic potential\nand their location in the \\textbf{k} space. It is shown that the Fermi velocity\nmodulation breaks the symmetry between the electron and hole minibands and that\nit is possible to control the behavior of the extra Dirac points. The results\nobtained here can be used in the fabrication of graphene-based electronic\ndevices."
    },
    {
        "anchor": "Lattice Dynamics and Thermal Equation of State of Platinum: Platinum is widely used as a pressure calibration standard. However, the\nestablished thermal EOS has uncertainties, especially in the high $P$-$T$\nrange. We use density functional theory to calculate the thermal equation of\nstate of platinum, up to 550 GPa and 5000 K. The static lattice energy is\ncomputed by using the LAPW method, with LDA, PBE, and the recently proposed WC\nfunctional. The electronic thermal free energy is evaluated using the Mermin\nfunctional. The vibrational part is computed within the quasi-harmonic\napproximation using density functional perturbation theory and\npseudopotentials. Special attention is paid to the influence of the electronic\ntemperature to the phonon frequencies. We find that in overall LDA results\nagree best with the experiments. Based on the DFT calculations and the\nestablished experimental data, we develop a consistent thermal EOS of platinum\nas a reference for pressure calibration.",
        "positive": "Quasiparticles and Band Transport in Organized Nanostructures of\n  Donor-Acceptor Copolymers: The performance of organic semiconductor devices is linked to highly-ordered\nnanostructures of self-assembled molecules and polymers. We employ many-body\nperturbation theory and study the excited states in bulk compolymers. We\ndiscover that acceptors in the polymer scaffold introduce a, hitherto\nunrecognized, conduction impurity band. The donor units are surrounded by\nconjugated bands which are only mildly perturbed by the presence of acceptors.\nAlong the polymer axis, mutual interactions among copolymer strands hinder\nefficient band transport, which is, however, strongly enhanced across\nindividual chains. We find that holes are most effectively transported in the\n$\\pi-\\pi$ stacking while electrons in the impurity band follow the edge-to-edge\ndirections. The copolymers exhibit regions with inverted transport polarity, in\nwhich electrons and holes are efficiently transported in mutually orthogonal\ndirections."
    },
    {
        "anchor": "DMC-ICE13: ambient and high pressure polymorphs of ice from Diffusion\n  Monte Carlo and Density Functional Theory: Ice is one of the most important and interesting molecular crystals\nexhibiting a rich and evolving phase diagram. Recent discoveries mean that\nthere are now twenty distinct polymorphs; a structural diversity that arises\nfrom a delicate interplay of hydrogen bonding and van der Waals dispersion\nforces. This wealth of structures provides a stern test of electronic structure\ntheories, with Density Functional Theory (DFT) often not able to accurately\ncharacterise the relative energies of the various ice polymorphs. Thanks to\nrecent advances that enable the accurate and efficient treatment of molecular\ncrystals with Diffusion Monte Carlo (DMC), we present here the DMC-ICE13\ndataset; a dataset of lattice energies of 13 ice polymorphs. This dataset\nencompasses the full structural complexity found in the ambient and\nhigh-pressure molecular ice polymorphs and when experimental reference energies\nare available our DMC results deliver sub-chemical accuracy. Using this dataset\nwe then perform an extensive benchmark of a broad range of DFT functionals. Of\nthe functionals considered, we find revPBE-D3 and RSCAN to reproduce reference\nabsolute lattice energies with the smallest error, whilst optB86b-vdW and\nSCAN+rVV10 have the best performance on the relative lattice energies. Our\nresults suggest that a single functional achieving reliable performance for all\nphases is still missing, and that care is needed in the selection of the most\nappropriate functional for the desired application. The insights obtained here\nmay also be relevant to liquid water and other hydrogen bonded and dispersion\nbonded molecular crystals.",
        "positive": "Simulation Studies of Nanomagnet-Based Architecture: We report a simulation study on interacting ensembles of Co nanomagnets that\ncan perform basic logic operations and propagate logic signals, where the state\nvariable is the magnetization direction. Dipole field coupling between\nindividual nanomagnets drives the logic functionality of the ensemble and\ncoordinated arrangements of the nanomagnets allow for the logic signal to\npropagate in a predictable way. Problems with the integrity of the logic signal\narising from instabilities in the constituent magnetizations are solved by\nintroducing a biaxial anisotropy term to the Gibbs magnetic free energy of each\nnanomagnet. The enhanced stability allows for more complex components of a\nlogic architecture capable of random combinatorial logic, including horizontal\nwires, vertical wires, junctions, fanout nodes, and a novel universal logic\ngate. Our simulations define the focus of scaling trends in nanomagnet-based\nlogic and provide estimates of the energy dissipation and time per nanomagnet\nreversal."
    },
    {
        "anchor": "Physics of thin-film ferroelectric oxides: This review covers the important advances in recent years in the physics of\nthin film ferroelectric oxides, the strongest emphasis being on those aspects\nparticular to ferroelectrics in thin film form. We introduce the current state\nof development in the application of ferroelectric thin films for electronic\ndevices and discuss the physics relevant for the performance and failure of\nthese devices. Following this we cover the enormous progress that has been made\nin the first principles computational approach to understanding ferroelectrics.\nWe then discuss in detail the important role that strain plays in determining\nthe properties of epitaxial thin ferroelectric films. Finally, we look at the\nemerging possibilities for nanoscale ferroelectrics, with particular emphasis\non ferroelectrics in non conventional nanoscale geometries.",
        "positive": "Multiexciton molecules in the hexaborides: We investigate multiexciton bound states in a semiconducting phase of\ndivalent hexaborides. Due to three degenerate valleys in both the conduction\nand valence bands the binding energy of a 6-exciton molecule is greatly\nenhanced by the shell effect. The ground state energies of multiexciton\nmolecules are calculated using the density functional formalism. We also show\nthat charged impurities stabilize multiexciton complexes leading to\ncondensation of localized excitons. These complexes can act as nucleation\ncenters of local moments."
    },
    {
        "anchor": "Optical response of supported particles: The present work reports a general method for the calculation of t he\npolarizability of a truncated sphere on a substrate. A multipole ex pansion is\nused, where the multipoles are not necessarily localized in the center of the\nsphere but can freely move on the revolution axis. From the weak formulation of\nthe boundary conditions, an infinite set of linear equations for the multipole\ncoefficients is derived. To obta in this set, the interaction between the\nisland and the substrate is t aken into account by the technique of image\nmultipoles. For numerical implementation, this set is truncated at an arbitrary\nmu ltipole order. The accuracy of the method is jugded through the stabil ity\nof the truncated sphere polarizability and the the fulfilment of t he boundary\nconditions which are demonstrated to be satisfied in large regions of the\nparameter space. This method brings an improvement wit h respect to the\nBedeaux's case \\cite{Wind87a,Wind87b} where the multi poles are located in the\ncenter of the sphere.",
        "positive": "Diffusion-free photon upconversion driven by intramolecular\n  triplet-triplet annihilation in engineered conjugated chromophores: The photon upconversion based on sensitized triplet-triplet annihilation\n(sTTA-UC) is a spin-flip mechanism exploited to recover the energy of dark\ntriplet states in conjugated systems. In this process a high-energy fluorescent\nsinglet is created through the collision and fusion of two low-energy triplets\nbelonging to different diffusing molecules. Its excellent yield in solution\nunder low excitation intensity and non-coherent light highlighted the huge\npotential of sTTA-UC to provide a breakthrough in solar technologies. However,\nits diffusion-limited bi-molecular nature limits its efficiency in the solid\nstate. To overcome this issue, we designed a molecular systems able to host\nsimultaneously more than one triplet, thus enabling a diffusion-free\nintramolecular TTA. We obtain the first direct demonstration of intramolecular\ntriplet fusion by tailored photoluminescence spectroscopy experiments, thus\nopening the way to realize a new family of single molecule upconverters with\nhuge potential in solar and lightening technologies by accessing the natural\ntriplets energy reservoir."
    },
    {
        "anchor": "Prediction of the electron density of states for crystalline compounds\n  with Atomistic Line Graph Neural Networks (ALIGNN): Machine learning (ML) based models have greatly enhanced the traditional\nmaterials discovery and design pipeline. Specifically, in recent years,\nsurrogate ML models for material property prediction have demonstrated success\nin predicting discrete scalar-valued target properties to within reasonable\naccuracy of their DFT-computed values. However, accurate prediction of spectral\ntargets such as the electron Density of States (DOS) poses a much more\nchallenging problem due to the complexity of the target, and the limited amount\nof available training data. In this study, we present an extension of the\nrecently developed Atomistic Line Graph Neural Network (ALIGNN) to accurately\npredict DOS of a large set of material unit cell structures, trained to the\npublicly available JARVIS-DFT dataset. Furthermore, we evaluate two methods of\nrepresentation of the target quantity - a direct discretized spectrum, and a\ncompressed low-dimensional representation obtained using an autoencoder.\nThrough this work, we demonstrate the utility of graph-based featurization and\nmodeling methods in the prediction of complex targets that depend on both\nchemistry and directional characteristics of material structures.",
        "positive": "Importance of strain reduction in improvement of optical transmission\n  and conductance in Si4+ doped ZnO: a probable new moisture resistant\n  Transparent Conductive Oxide: Si doped ZnO has been reported to be a better conductor than pure ZnO. It is\nreported that carrier density increases and hence conductivity increases.\nHowever, the effect on optical transmission is yet not clear until our recent\nreport [1]. Zn1-xSixO for x= 0, 0.013, 0.020 and 0.027 have been synthesized\nusing sol-gel method (a citric acid-glycerol route) followed by solid state\nsintering. We found that there is a decrease in defect states due to Si doping.\nThe correlation of strain to the decrement in vacancy sites is discussed in\nthis report. In modern electronics and solar cell fabrication, transparent\nconductive oxides (TCOs) are important components which conduct electrically\nwithout absorbing visible light. Known TCOs are extremely costly and are\ncomposed of non-abundant elements. Search for new ecofriendly, cheap and\nsustainable TCOs has been a recent research of attraction. Keeping in mind that\nmost solar cells are exposed to natural conditions, the humidity tolerance\nbecomes a determining factor. We report that sensitivity to moisture decreases\ndrastically while the conductivity and optical transparency increases with\ndoping. The reduction of strain and improvement of transport properties results\nin increased conductivity of Si doped ZnO pellets, tempting us to envisage this\nmaterial as a probable alternate TCO."
    },
    {
        "anchor": "Two-magnon frequency-pulling effect in ferromagnetic resonance: We report the experimental observation in thin films of the hybridization of\nthe uniform ferromagnetic resonance mode with nonuniform magnons as a result of\nthe two-magnon scattering mechanism, leading to a frequency-pulling effect on\nthe ferromagnetic resonance. This effect, when not properly accounted for,\nleads to a discrepancy in the dependence of the ferromagnetic resonance field\non frequency for different field orientations. The frequency-pulling effect is\nthe complement of the broadening of the ferromagnetic resonance lineshape by\ntwo-magnon scattering and can be calculated using the same parameters. By\naccounting for the two-magnon frequency shifts through these means, consistency\nis achieved in fitting data from in-plane and perpendicular-to-plane resonance\nconditions.",
        "positive": "Pressure influence on excitonic luminescence of CsPbBr3 perovskite: This study investigates the effect of hydrostatic pressure on the\nluminescence properties of CsPbBr3 single crystals at 12 K. The luminescence at\nthe edge of the band gap reveals a structure attributed to free excitons,\nphonon replica of the free excitons, and Rashba excitons. Changes in the\nrelative intensity of the free and Rashba excitons were observed with\nincreasing pressure, caused by changes in the probability of nonradiative\ndeexcitation. At pressures around 3 GPa, luminescence completely fades away.\nThe red shift of the energy position of the maximum luminescence of free and\nRashba excitons in pressure ranges of 0-1.3 GPa is attributed to the length\nreduction of Pb-Br bonds in [PbBr6]4- octahedra, while the high-energy shift of\nthe Rashba excitons at pressures above 1.3 GPa is due to [PbBr6]4- octahedra\nrotation and changes in the Pb-Br_Pb angle."
    },
    {
        "anchor": "Silk reinforced with graphene or carbon nanotubes spun by spiders: Here, we report the production of silk incorporating graphene and carbon\nnanotubes directly by spider spinning, after spraying spiders with the\ncorresponding aqueous dispersions. We observe a significant increment of the\nmechanical properties with respect to the pristine silk, in terms of fracture\nstrength, Young's and toughness moduli. We measure a fracture strength up to\n5.4 GPa, a Young's modulus up to 47.8 GPa and a toughness modulus up to 2.1\nGPa, or 1567 J/g, which, to the best of our knowledge, is the highest reported\nto date, even when compared to the current toughest knotted fibres. This\napproach could be extended to other animals and plants and could lead to a new\nclass of bionic materials for ultimate applications.",
        "positive": "Carrier-induced ferromagnetism in 2D magnetically-doped semiconductor\n  structures: We show theoretically that the magnetic ions, randomly distributed in a\ntwo-dimensional (2D) semiconductor system, can generate a ferromagnetic\nlong-range order via the RKKY interaction. The main physical reason is the\ndiscrete (rather than continuous) symmetry of the 2D Ising model of the\nspin-spin interaction mediated by the spin-orbit coupling of 2D free carriers,\nwhich precludes the validity of the Mermin-Wagner theorem. Further, the\nanalysis clearly illustrates the crucial role of the molecular field\nfluctuations as opposed to the mean field. The developed theoretical model\ndescribes the desired magnetization and phase-transition temperature $T_c$ in\nterms of a single parameter; namely, the chemical potential $\\mu$. Our results\nhighlight a path way to reach the highest possible $T_c$ in a given material as\nwell as an opportunity to control the magnetic properties externally (e.g., via\na gate bias). Numerical estimations show that magnetic impurities such as\nMn$^{2+}$ with spins $S=5/2$ can realize ferromagnetism with $T_c$ close to\nroom temperature."
    },
    {
        "anchor": "Towards truly simultaneous PIXE and RBS analysis of layered objects in\n  cultural heritage: For a long time, RBS and PIXE techniques have been used in the field of\ncultural heritage. Although the complementarity of both techniques has long\nbeen acknowledged, its full potential has not been yet developed due to the\nlack of general purpose software tools for analysing the data from both\ntechniques in a coherent way. In this work we provide an example of how the\nrecent addition of PIXE to the set of techniques supported by the DataFurnace\ncode can significantly change this situation. We present a case in which a non\nhomogeneous sample (an oxidized metal from a photographic plate -heliography-\nmade by Niepce in 1827) is analysed using RBS and PIXE in a straightforward and\npowerful way that can only be performed with a code that treats both techniques\nsimultaneously as a part of one single and coherent analysis. The optimization\ncapabilities of DataFurnace, allowed us to obtain the composition profiles for\nthese samples in a very simple way.",
        "positive": "Chemisorption Induced Formation of Biphenylene Dimer on Surfaces: We report an example that demonstrates the clear interdependence between\nsurface-supported reactions and molecular adsorption configurations. Two\nbiphenyl-based molecules with two and four bromine substituents, i.e.\n2,2-dibromo-biphenyl (DBBP) and 2,2,6,6-tetrabromo-1,1-biphenyl (TBBP), show\ncompletely different reaction pathways on a Ag(111) surface, leading to the\nselective formation of dibenzo[e,l]pyrene and biphenylene dimer, respectively.\nBy combining low-temperature scanning tunneling microscopy, synchrotron\nradiation photoemission spectroscopy, and density functional theory\ncalculations, we unravel the underlying reaction mechanism. After\ndebromination, a bi-radical biphenyl can be stabilized by surface Ag adatoms,\nwhile a four-radical biphenyl undergoes spontaneous intramolecular annulation\ndue to its extreme instability on Ag(111). Such different chemisorption-induced\nprecursor states between DBBP and TBBP consequently lead to different reaction\npathways after further annealing. In addition, using bond-resolving scanning\ntunneling microscopy and scanning tunneling spectroscopy, we determine the bond\nlength alternation of biphenylene dimer product with atomic precision, which\ncontains four-, six-, and eight-membered rings. The four-membered ring units\nturn out to be radialene structures."
    },
    {
        "anchor": "Flow-Through Porous Silicon Membranes for Real-Time Label-Free\n  Biosensing: A flow-through sensing platform based on open-ended porous silicon (PSi)\nmicrocavity membranes that are compatible with integration in on-chip sensor\narrays is demonstrated. Due to the high aspect ratio of PSi nanopores, the\nperformance of closed-ended PSi sensors is limited by infiltration challenges\nand slow sensor responses when detecting large molecules such as proteins and\nnucleic acids. In order to improve molecule transport efficiency and reduce\nsensor response time, open-ended PSi nanopore membranes were used in a\nflow-through sensing scheme, allowing analyte solutions to pass through the\nnanopores. The molecular binding kinetics in these PSi membranes were compared\nthrough experiments and simulation with those from closed-ended PSi films of\ncomparable thickness in a conventional flow-over sensing scheme. The\nflow-through PSi membrane resulted in a six-fold improvement in sensor response\ntime when detecting a high molecular weight analyte (streptavidin) versus in\nthe flow-over PSi approach. This work demonstrates the possibility of\nintegrating multiple flow-through PSi sensor membranes within parallel\nmicroarrays for rapid and multiplexed label-free biosensing.",
        "positive": "Lieb-Mattis ferrimagnetism in diluted magnetic semiconductors: We show the possibility of long-range ferrimagnetic ordering with a\nsaturation magnetisation of the order of 1 Bohr magneton per spin for\narbitrarily low concentration of magnetic impurities in semiconductors,\nprovided that the impurities form a superstructure satisfying the conditions of\nthe Lieb-Mattis theorem. Explicit examples of such superstructures are given\nfor the wurtzite lattice, and the temperature of ferrimagnetic transition is\nestimated from a high-temperature expansion. Exact diagonalization studies show\nthat small fragments of the structure exhibit enhanced magnetic response and\nisotropic superparamagnetism at low temperatures. A quantum transition in a\nhigh magnetic field is considered and similar superstructures in cubic\nsemiconductors are discussed as well."
    },
    {
        "anchor": "Effect of ball milling and post annealing on structural and magnetic\n  properties in Ni50Mn36Fe2Sb12 Heusler alloy: The effect of ball milling on the structural, magnetic and exchange bias\nproperties of Ni50Mn36Fe2Sb12 Heusler alloys was studied. The ball milled\nsamples exhibited coexisting austenite and martensite phases at room\ntemperature, while annealing supresses the austenite phase completely. Ball\nmilling was found to reduce the grain size, which resulted in the weakening of\nthe ferromagnetic properties. An exchange bias field of 111 Oe and coercivity\nof 826 Oe were observed at 5 K in the as-milled sample, in contrast to the bulk\nalloy values of 288 Oe and 292 Oe, respectively. Annealing causes an increase\nin the ferromagnetic ordering and a decrease in the interfacial exchange\ncoupling, resulting in a decrease of both exchange bias and coercivity.",
        "positive": "Model hamiltonians in density functional theory: The formalism of Kohn and Sham uses a specific (model) hamiltonian which\nhighly simplifies the many-electron problem to that of noninteracting fermions.\nThe theorem of Hohenberg and Kohn tells us that, for a given ground state\ndensity, this hamiltonian is unique. In principle, this density can be chosen\nas that of the real, interacting system. To obtain the energy, or other\nproperties of the real system, approximations are needed. Working with non\ninteracting fermions is an important simplification, but it may be easier to\nproduce approximations with different choices of the model hamiltonian. The\nfeature that the exact density is (ideally) reproduced can be kept in the newly\ndefined fictitious systems. Using model hamiltonians having the same form as\nthe physical one, that is, being built of one- and two-body operators, allows\nto approach the physical hamiltonian arbitrarily close, and thus a systematic\nreduction of the approximations."
    },
    {
        "anchor": "Prediction of a Two-dimensional Sulfur Nitride (S3N2) Solid for\n  Nanoscale Optoelectronic Applications: Two-dimensional materials have attracted tremendous attention for their\nfascinating electronic, optical, chemical and mechanical properties. However,\nthe band gaps of most 2D materials reported are smaller than 2.0 eV, which\ngreatly restricted their optoelectronic applications in blue and ultraviolet\nrange of the spectrum. Here, we propose a new stable sulfur nitride (S3N2) 2D\ncrystal that is a covalent network composed solely of S-N {\\sigma} bonds. S3N2\ncrystal is dynamically stable as confirmed by the computed phonon spectrum and\nab initio molecular dynamics simulations in the NPT ensemble. Hybrid density\nfunctional calculations show that 2D S3N2 crystal is a wide, direct band-gap\n(3.17 eV) semiconductor with good hole mobility. These fascinating electronic\nproperties could pave the way for its optoelectronic applications such as blue\nor ultra-violet light-emitting diodes (LEDs) and photodetectors.",
        "positive": "Thermodynamics of carbon point defects in hexagonal boron nitride: We present a first-principles computational study of the thermodynamics of\ncarbon defects in hexagonal boron nitride (hBN). The defects considered are\ncarbon monomers, dimers, trimers, and larger carbon clusters, as well as\ncomplexes of carbon with vacancies, antisites, and substitutional oxygen. Our\ncalculations show that monomers ($\\text{C}_{\\text{B}}$, $\\text{C}_{\\text{B}}$),\ndimers, trimers, and $\\text{C}_{\\text{N}}\\text{O}_{\\text{N}}$ pairs are the\nmost prevalent species under most growth conditions. Compared to these defects,\nlarger carbon clusters, as well as complexes of carbon with vacancies and\nantisites, occur at much smaller concentrations. Our results are discussed in\nview of the relevance of carbon defects in single-photon emission in hBN."
    },
    {
        "anchor": "High performance THz emitters based on ferromagnetic/nonmagnetic\n  heterostructures: We report a THz emitter with excellent performances based on nonmagnetic (NM)\nand ferromagnetic (FM) heterostructures. The spin currents are first excited by\nthe femtosecond laser beam in the NM/FM bilayer, and then transient charge\ncurrents are generated by inverse spin Hall effect, leading to THz emission out\nof the structure. The broadband THz waves emitted from our film stacks have a\npeak intensity exceeding 500 um thick ZnTe crystals (standard THz emitters).\nOur device is insensitive to the polarization of an incident laser beam which\nindicates the noise resistive feature. In contrast, the polarization of THz\nwaves is fully controllable by an external magnetic field. We have also\nfabricated the devices on flexible substrates with a great performance, and\ndemonstrated that the devices can be driven by low power lasers. Together with\nthe low cost and mass productive sputtering growth method for the film stacks,\nthe proposed THz emitters can be readily applied to a wide range of THz\nequipment. Our study also points towards an alternative approach to\ncharacterize spintronic devices with NM/FM bilayers.",
        "positive": "Features of charge transport in Mo/n-Si structures with a Shottky\n  barrier: The forward and reverse current-voltage characteristics of the Mo/n-Si\nSchottky barrier structures have been studied experimentally in the temperature\nrange 130-330 K. It is found that Shottky barrier height increases and time\nideality factor decreases with temperature increasing. The obtained results\nhave been analyzed in the framework of inhomogeneous contact model. The mean\nand standart deviation of Shottky barrier heigh are determined: 0.872 V and\n0.099 V at $=130-220 K and 0.656 V and 0.036 V at T=230-330 K respectively. It\nis shown that at reverse bias the main processes of current flow are the\nthermionic emission over an inhomogeneous barrier and tunneling."
    },
    {
        "anchor": "Temperature dependence of the spin relaxation in highly degenerate ZnO\n  thin films: Zinc oxide is a wide-bandgap semiconductor which is considered a potential\ncandidate for fabricating next-generation transparent spintronic devices.\nHowever, before this can be practically achieved, a thorough, scientific\nunderstanding of the various spin transport and relaxation processes undergone\nin this material is essential. In the present paper we report our\ninvestigations into these processes via temperature dependent, non-local Hanle\nexperiments. Epitaxial ZnO thin films were deposited on c-axis sapphire\nsubstrates using a pulsed laser deposition technique. Careful structural,\noptical, and electrical characterizations of the films were performed.\nTemperature dependent Hanle measurements were carried out, using an\nall-electrical scheme for spin injection and detection, in a non-local geometry\nover the temperature range of 20 - 300 K. Carrier concentration in these films,\nas determined by Hall effect measurements, was found to be of the order of\n10^19 cm^-3. It was determined that in such a degenerately doped system it is\nessential to use Fermi-Dirac statistics to explain the transport of carriers in\nthe system. From the Hanle data, spin relaxation time in the ZnO films was\ndetermined at different temperatures. Our analysis of the temperature-dependent\nspin relaxation time data suggests that the dominant mechanism of spin\nrelaxation in ZnO films is the Dyakonov-Perel (DP) mechanism modified for the\nwurtzite crystalline structure in which a hexagonal c-axis reflection asymmetry\nis present. As a result of this modification the spin-relaxation rate is\nlinear-in-momentum.",
        "positive": "Adsorption of Oxygen Molecules on Individual Carbon Single-walled\n  Nanotubes: Our study of the adsorption of oxygen molecules on individual semiconductiong\nsingle-walled carbon nanotubes at ambient conditions reveals that the\nadsorption is physisorption, that the resistance without O2 increases by ~two\norders of magnitude as compared to that with O2, and that the sensitive\nresponse is due to the pinning of the Fermi level near the top of the valence\nband of the tube resulting from impurity states of O2 appearing above the\nvalence band."
    },
    {
        "anchor": "Tuning the coexistence regime of incomplete and tubular skyrmions in\n  ferro/ferri/ferromagnetic trilayers: The development of skyrmionic devices requires a suitable tuning of material\nparameters in order to stabilize skyrmions and control their density. It has\nbeen demonstrated recently that different skyrmion types can be simultaneously\nstabilized at room temperature in heterostructures involving ferromagnets,\nferrimagnets and heavy metals, offering a new platform of coding binary\ninformation in the type of skyrmion instead of the presence/absence of\nskyrmions. Here, we tune the energy landscape of the two skyrmion types in such\nheterostructures by engineering the geometrical and material parameters of the\nindividual layers. We find that a fine adjustment of the ferromagnetic layer\nthickness and thus its magnetic anisotropy, allows the trilayer system to\nsupport either one of the skyrmion types or the coexistence of both and with\nvarying densities.",
        "positive": "Evaluation of Exchange-Correlation Energy, Potential, and Stress: We describe a method for calculating the exchange and correlation (XC)\ncontributions to the total energy, effective potential, and stress tensor in\nthe generalized gradient approximation. We avoid using the analytical\nexpressions for the functional derivatives of E_xc*rho, which depend on\ndiscontinuous second-order derivatives of the electron density rho. Instead, we\nfirst approximate E_xc by its integral in a real space grid, and then we\nevaluate its partial derivatives with respect to the density at the grid\npoints. This ensures the exact consistency between the calculated total energy,\npotential, and stress, and it avoids the need of second-order derivatives. We\nshow a few applications of the method, which requires only the value of the\n(spin) electron density in a grid (possibly nonuniform) and returns a\nconventional (local) XC potential."
    },
    {
        "anchor": "Single-walled Ising nanotube with opposite sign of interactions using\n  Wang-Landau algorithm: The effect of opposite sign of interactions in a single-walled Ising nanotube\nis investigated using the Wang-Landau algorithm. The thermodynamic observables\nare calculated from the estimated density of states (DOS) with and without the\npresence of an external magnetic field. Irrespective of the applied magnetic\nfield, a symmetric trend of DOS is observed for opposite sign of interactions\nwhich is in contrast to the asymmetric trend for same sign of interactions.\nFurther, two types of anti-ferromagnetic (AFM) orderings, namely A-type and\nC-type anti-ferromagnetic order, are observed for opposite sign of\ninteractions. These AFM spin orientations are switched to ferromagnetic (FM)\nphase by increasing the applied magnetic field ($B$). However, the spin\nordering changes from the ordered AFM/FM phase to a disordered paramagnetic\nphase by increasing the temperature. Phase diagram shows that these three\nphases coexist around $B=2.0$. This study indicates that, by properly tuning\nthe magnetic properties, the single-walled nanotube can be used for fabrication\nof new types of magnetic storage nano materials.",
        "positive": "Thermodynamics of Non-equilibrium Diffuse-Interfaces in Mesoscale Phase\n  Transformations: We present a new phase-field formulation for the non-equilibrium interface\nkinetics. The diffuse interface is considered an integral of numerous\nrepresentative volume elements (RVEs), in which there is a two-phase mixture\nwith two conserved and two non-conserved concentration fields. This particular\nway of separating concentration fields leads to two distinct dissipative\nprocesses besides the phase boundary migration, i.e., trans-sharp-interface\ndiffusion between different phases within a single RVE and\ntrans-diffuse-interface diffusion between different RVEs within a single phase.\nA two-part mechanism is proposed to balance the driving forces and energy\ndissipation for diffusionless and diffusional processes in RVEs. Moreover, the\nclassical interface friction and solute drag can be recovered by integrating\nthe diffuse interface. Compared with the sharp interface theory, the present\ndiffuse interface can reproduce the atomic simulated partial-drag\nself-consistently in thermodynamics."
    },
    {
        "anchor": "Design and proof of concept for silicon-based quantum dot quantum bits: Spins based in silicon provide one of the most promising architectures for\nquantum computing. Quantum dots are an inherently scalable technology. Here, we\ncombine these two concepts into a workable design for a silicon-germanium\nquantum bit. The novel structure incorporates vertical and lateral tunneling,\nprovides controlled coupling between dots, and enables single electron\noccupation of each dot. Precise modeling of the design elucidates its potential\nfor scalable quantum computing. For the first time it is possible to translate\nthe requirements of fault-tolerant error correction into specific requirements\nfor gate voltage control electronics in quantum dots. We demonstrate that these\nrequirements are met by existing pulse generators in the kHz-MHz range, but GHz\noperation is not yet achievable. Our calculations further pinpoint device\nfeatures that enhance operation speed and robustness against leakage errors. We\nfind that the component technologies for silicon quantum dot quantum computers\nare already in hand.",
        "positive": "MCBTE: A variance-reduced Monte Carlo solution of the linearized\n  Boltzmann transport equation for phonons: MCBTE solves the linearized Boltzmann transport equation for phonons in three\ndimensions using a variance-reduced Monte Carlo solution approach. The\nalgorithm is suited for both transient and steady-state analysis of thermal\ntransport in structured materials with size features in the nanometer to\nhundreds of microns range. The code is portable and integrated with both\nfirst-principles density functional theory calculations and empirical relations\nfor the input of phonon frequency, group velocity, and mean free path required\nfor calculating the thermal properties. The program outputs space- and\ntime-resolved temperature and heat flux for the transient study. For the\nsteady-state simulations, the frequency-resolved contribution of phonons to\ntemperature and heat flux is written to the output files, thus allowing the\nstudy of cumulative thermal conductivity as a function of phonon frequency or\nmean free path. We provide several illustrative examples, including ballistic\nand quasi-ballistic thermal transport, the thermal conductivity of thin films\nand periodic nanostructures, to demonstrate the functionality and to benchmark\nour code against available theoretical/analytical/computational results from\nthe literature. Moreover, we parallelize the code using the Matlab Distributed\nComputing Server, providing near-linear scaling with the number of processors."
    },
    {
        "anchor": "Evaporation Dynamics of Sessile Saline Microdroplets in Oil: The occurrence of concentration and temperature gradients in saline\nmicrodroplets evaporating directly in air makes them unsuitable for nucleation\nstudies where homogeneous composition is required. This can be addressed by\nimmersing the droplet in oil under regulated humidity and reducing the volume\nto the picoliter range. However, the evaporation dynamics of such a system is\nnot well understood. In this work, we present evaporation models applicable for\narrays of sessile microdroplets with dissolved solute submerged in a thin layer\nof oil. Our model accounts for the variable diffusion distance due to the\npresence of the oil film separating the droplet and air, the diffusive\ninteraction of neighboring droplets, as well as the variation of the solution\ndensity and water activity due to the evolving solute concentration. Our model\nshows excellent agreement with experimental data for both pure water and NaCl\nsolution. With this model, we demonstrate that assuming a constant evaporation\nrate and neglecting the diffusive interactions can lead to severe inaccuracies\nin the measurement of droplet concentration particularly during nucleation\nexperiments. Given the significance of droplet evaporation in a wide array of\nscientific and industrial applications, the models and insights presented\nherein would be of great value to many fields of interest.",
        "positive": "Time-dependent Density Functional calculation of e-H scattering: Phase shifts for single-channel elastic electron-atom scattering are derived\nfrom time-dependent density functional theory. The H$^-$ ion is placed in a\nspherical box, its discrete spectrum found, and phase shifts deduced.\nExact-exchange yields an excellent approximation to the ground-state Kohn-Sham\npotential, while the adiabatic local density approximation yields good singlet\nand triplet phase shifts."
    },
    {
        "anchor": "Localization and magnetism of the resonant impurity states in Ti doped\n  PbTe: The problem of localization of the resonant impurity states is discussed for\nan illustrative example of Titanium doped Lead Telluride. Electronic structure\nof PbTe:Ti is studied using first principles methods, densities of states and\nBloch spectral functions are analyzed. We show that Ti creates resonant states\nin the conduction band of PbTe, however, spectral functions of the system\nstrongly suggest localization of these states and show poor hybridization with\nPbTe electronic structure. The contrast between results presented here and\npreviously reported spectral functions for PbTe:Tl correlate very well with the\ndifferent effect of those impurities on thermopower (S) of PbTe, which is large\nincrease is S for PbTe:Tl and almost no effect on S for PbTe:Ti. Moreover,\nmagnetic properties of the system are studied and formation of magnetic moments\non Ti atoms is found, both for ordered (ferromagnetic) and disordered\n(paramagnetic-like) phases, showing that PbTe:Ti can be a magnetic\nsemiconductor.",
        "positive": "Multiferroicity in Geometrically Frustrated \u03b1-MCr_2O_4 systems\n  (M=Ca, Sr, Ba): We have successfully synthesized three quasi-2D geometrically frustrated\nmagnetic compounds (\\alpha-MCr_2O_4, M=Ca, Sr, Ba) using the\nspark-plasma-sintering technique. All these members of the \\alpha-MCr_2O_4\nfamily consist of the stacking planar triangular lattices of Cr$^{3+}$ spins\n(${\\rm S}=3/2$), separated by non-magnetic alkaline earth ions. Their\ncorresponding magnetic susceptibility, specific heat, dielectric permittivity\nand ferroelectric polarization are systematically investigated. A long-range\nmagnetic ordering arises below the N\\'{e}el temperature (around 40K) in each\nmember of the \\alpha-MCr_2O_4 family, which changes to the quasi-120\\degree\nproper-screw-type helical spin structure at low temperature. A very small but\nconfirmed spontaneous electric polarization emerges concomitantly with this\nmagnetic ordering. The direction of electric polarization is found within the\nbasal triangular plane. The multiferroicity in \\alpha-MCr_2O_4 can not be\nexplained within the frameworks of the magnetic exchange striction or the\ninverse Dzyaloshinskii-Moriya interaction. The observed results are more\ncompatible with the newly proposed Arima mechanism that is associated the d-p\nhybridization between the ligand and transition metal ions, modified by the\nspin-orbit coupling. The evolution of multiferroic properties with the\nincreasing inter-planar spacing (as M changes from Ca to Ba) reveals the\nimportance of interlayer interaction in this new family of frustrated magnetic\nsystems."
    },
    {
        "anchor": "Investigation of Room Temperature Ferroelectricity and Ferrimagnetism in\n  Multiferroic AlxFe2-xO3 Epitaxial Thin Films: Multiferroic materials open up the possibility to design novel functionality\nin electronic devices, with low energy consumption. However, there are very few\nmaterials that show multiferroicity at room temperature, which is essential to\nbe practically useful. AlxFe2-xO3 (x-AFO) thin films, belonging to the k-Al2O3\nfamily are interesting because they show room temperature ferrimagnetism and\nhave a polar crystal structure. However, it is difficult to realise its\nferroelectric properties at room temperature, due to low resistivity of the\nfilms. In this work, we have deposited x-AFO (0.5 <= x <= 1) epitaxial thin\nfilms with low leakage, on SrTiO3<111> substrates by Pulsed Laser Deposition.\nMagnetic measurements confirmed room temperature ferrimagnetism of the films,\nhowever the Curie temperature was found to be influenced by deposition\nconditions. First principle calculations suggested that ferroelectric domain\nswitching occurs through shearing of in-plane oxygen layers, and predicted a\nhigh polarization value of 24 uC/cm2. However, actual ferroelectric\nmeasurements showed the polarization to be two order less. Presence of multiple\nin-plane domains which oppose polarization switching of adjacent domains, was\nfound to be the cause for the small observed polarization. Comparing dielectric\nrelaxation studies and ferroelectric characterization showed that\noxygen-vacancy defects assist domain wall motion, which in turn facilitates\npolarization switching.",
        "positive": "Electronic structure of negative charge transfer CaFeO3 across the\n  metal-insulator transition: We investigated the metal-insulator transition for epitaxial thin films of\nthe perovskite CaFeO3, a material with a significant oxygen ligand hole\ncontribution to its electronic structure. We find that biaxial tensile and\ncompressive strain suppress the metal-insulator transition temperature. By\ncombining hard X-ray photoelectron spectroscopy, soft X-ray absorption\nspectroscopy, and density functional calculations, we resolve the\nelement-specific changes to the electronic structure across the metal-insulator\ntransition. We demonstrate that the Fe electron valence undergoes no observable\nchange between the metallic and insulating states, whereas the O electronic\nconfiguration undergoes significant changes. This strongly supports the\nbond-disproportionation model of the metal-insulator transition for CaFeO3 and\nhighlights the importance of ligand holes in its electronic structure. By\nsensitively measuring the ligand hole density, however, we find that it\nincreases by ~5-10% in the insulating state, which we ascribe to a further\nlocalization of electron charge on the Fe sites. These results provide detailed\ninsight into the metal-insulator transition of negative charge transfer\ncompounds and should prove instructive for understanding metal-insulator\ntransitions in other late transition metal compounds such as the nickelates."
    },
    {
        "anchor": "Investigation of scaling properties of hysteresis in Finemet thin films: We study the behavior of hysteresis loops in Finemet\nFe$_{73.5}$Cu$_1$Nb$_3$Si$_{18.5}$B$_4$ thin films by using a fluxometric setup\nbased on a couple of well compensated pickup coils. The presence of scaling\nlaws of the hysteresis area is investigated as a function of the amplitude and\nfrequency of the applied field, considering sample thickness from about 20 nm\nto 5 $\\mu$m. We do not observe any scaling predicted by theoretical models,\nwhile dynamic loops show a logarithmic dependence on the frequency.",
        "positive": "Ab initio calculations of the hydrogen bond: Recent x-ray Compton scattering experiments in ice have provided useful\ninformation about the quantum nature of the interaction between H$_2$O\nmonomers. The hydrogen bond is characterized by a certain amount of charge\ntransfer which could be determined in a Compton experiment. We use ab-initio\nsimulations to investigate the hydrogen bond in H$_2$O structures by\ncalculating the Compton profile and related quantities in three different\nsystems, namely the water dimer, a cluster containing 12 water molecules and\nthe ice crystal. We show how to extract estimates of the charge transfer from\nthe Compton profiles."
    },
    {
        "anchor": "Spherical spin-orientation degeneracy of basic antiferromagnetic\n  configurations due to the dipolar interaction in cubic lattices: Based on a simple general relation for the Lorentz field, the precise values\nare obtained for the energies of ferromagnetic and basic antiferromagnetic\nstates in sc, bcc, fcc, and diamond cubic lattices. Within both the\n'nearest-neighbor' and group-theoretic approaches, a large variety of\nantiferromagnetic states revealed as corresponding to the lowest energies is\naddressed, with recognizing their spherical spin-orientation degeneracy, which\nturns out to be rather special in fcc lattices.",
        "positive": "Magnetic freezing transition in a CoO/Permalloy bilayer revealed by\n  transverse ac susceptibility: We utilize variable-temperature, variable-frequency magneto-optical\ntransverse magnetic susceptibility technique to study the static and dynamical\nmagnetic properties of a thin-film CoO/Permalloy bilayer. Our measurements\ndemonstrate that in the studied system, the directional asymmetry of the\nhysteresis loop is associated mainly with the difference in the reversal\nmechanisms between the two reversed states of magnetization stabilized by the\nexchange-induced uniaxial anisotropy. The latter is found to be much larger\nthan the exchange-induced unidirectional anisotropy of the ferromagnet. We also\nobserve an abrupt variation of the frequency-dependent imaginary part of ac\nsusceptibility near the exchange bias blocking temperature, consistent with the\nmagnetic freezing transition inferred from the previous time-domain studies of\nmagnetic aging in similar systems. The developed measurement approach enables\nprecise characterization of the dynamical and static characteristics of\nthin-film magnetic heterostructures that can find applications in\nreconfigurable magnonic and neuromorphic circuits."
    },
    {
        "anchor": "Ordered Array of Single Au Adatoms with Remarkable Thermal Stability:\n  Au/Fe3O4(001): We present a Scanning Tunneling Microscopy (STM) investigation of gold\ndeposited at the magnetite Fe3O4(001) surface at room temperature. This surface\nforms a reconstruction with (\\surd2\\times\\surd2)R45{\\deg} symmetry, where pairs\nof Fe and neighboring O ions are slightly displaced laterally, forming\nundulating rows with 'narrow' and 'wide' adsorption sites. At fractional\nmonolayer coverages, single Au adatoms adsorb exclusively at the narrow sites,\nwith no significant sintering up to annealing temperatures of 400 {\\deg}C. The\nstrong preference for this site is possibly related to charge and orbital\nordering within the first subsurface layer of the reconstructed Fe3O4(001)\nsurface. Because of their high thermal stability, the ordered Au atoms at\nFe3O4(001)- (\\surd2\\times\\surd2)R45{\\deg} could provide useful for probing the\nchemical reactivity of single atomic species.",
        "positive": "Does the boson peak survive in an ultrathin oxide glass?: Bulk glasses exhibit extra vibrational modes at low energies, known as the\nboson peak. The microscopic dynamics in nanoscale alumina impact the\nperformance of qubits and other superconducting devices, however the existence\nof the boson peak in these glasses has not been previously measured. Here we\nreport neutron spectroscopy on Al/Al$_2$O$_{3-x}$ nanoparticles consisting of\nspherical metallic cores from 20 to 1000 nm surrounded by a 3.5 nm thick\nalumina glass. An intense low-energy peak is observed at $\\omega_{BP}$ = 2.8\n$\\pm$ 0.6 meV for highly oxidised particles, concurrent with an excess in the\ndensity of states. The intensity of the peak scales inversely with particle\nsize and oxide fraction indicating a surface origin, and is red-shifted by 3\nmeV with respect to the van-Hove singularity of $\\gamma$-phase Al$_2$O$_{3-x}$\nnanocrystals. Molecular dynamics simulations of $\\alpha$-Al$_2$O$_{3-x}$,\n$\\gamma$-Al$_2$O$_{3-x}$ and a-Al$_2$O$_{3-x}$ show that the observed boson\npeak is a signature of the ultrathin glass surface, and the frequency is\nsoftened compared to that of the hypothetical bulk glass."
    },
    {
        "anchor": "Enhanced orbital magnetic moments in magnetic heterostructures with\n  interface perpendicular magnetic anisotropy: We have studied the magnetic layer thickness dependence of the orbital\nmagnetic moment in magnetic heterostructures to identify contributions from\ninterfaces. Three different heterostructures, Ta/CoFeB/MgO, Pt/Co/AlO$_x$ and\nPt/Co/Pt, which possess significant interface contribution to the perpendicular\nmagnetic anisotropy, are studied as model systems. X-ray magnetic circular\ndichroism spectroscopy is used to evaluate the relative orbital moment, i.e.\nthe ratio of the orbital to spin moments, of the magnetic elements constituting\nthe heterostructures. We find that the relative orbital moment of Co in\nPt/Co/Pt remains constant against its thickness whereas the moment increases\nwith decreasing Co layer thickness for Pt/Co/AlO$_x$, suggesting that a\nnon-zero interface orbital moment exists for the latter system. For\nTa/CoFeB/MgO, a non-zero interface orbital moment is found only for Fe. X-ray\nabsorption spectra shows that a particular oxidized Co state in Pt/Co/AlO$_x$,\nabsent in other heterosturctures, may give rise to the interface orbital moment\nin this system. These results show element specific contributions to the\ninterface orbital magnetic moments in ultrathin magnetic heterostructures.",
        "positive": "Crack Front Segmentation and Facet Coarsening in Mixed-Mode Fracture: A planar crack generically segments into an array of \"daughter cracks\" shaped\nas tilted facets when loaded with both a tensile stress normal to the crack\nplane (mode I) and a shear stress parallel to the crack front (mode III). We\ninvestigate facet propagation and coarsening using in-situ microscopy\nobservations of fracture surfaces at different stages of quasi-static\nmixed-mode crack propagation and phase-field simulations. The results\ndemonstrate that the bifurcation from propagating planar to segmented crack\nfront is strongly subcritical, reconciling previous theoretical predictions of\nlinear stability analysis with experimental observations. They further show\nthat facet coarsening is a self- similar process driven by a spatial\nperiod-doubling instability of facet arrays with a growth rate dependent on\nmode mixity. Those results have important implications for understanding the\nfailure of a wide range of materials."
    },
    {
        "anchor": "Qualitative observation of reversible phase change in astrochemical\n  ethanethiol ices using infrared spectroscopy: Here we report the first evidence for a reversible phase change in an\nethanethiol ice prepared under astrochemical conditions. InfraRed (IR)\nspectroscopy was used to monitor the morphology of the ice using the S-H\nstretching vibration, a characteristic vibration of thiol molecules. The\ndeposited sample was able to switch between amorphous and crystalline phases\nrepeatedly under temperature cycles between 10 K and 130 K with subsequent loss\nof molecules in every phase change. Such an effect is dependent upon the\noriginal thickness of the ice. Further work on quantitative analysis is to be\ncarried out in due course whereas here we are reporting the first results\nobtained.",
        "positive": "Electron-phonon coupling as an order-one problem: The coupling between electrons and phonons plays important roles in physics,\nchemistry and biology. However, the accurate calculation of the electron-phonon\ncoupling constants is computationally expensive as it involves solving the\nSchrodinger equation for O(N) nuclear configurations, where N is the number of\nnuclei. Herein we show that by considering the forces on the nuclei caused by\nthe addition or subtraction of an arbitrarily small electronic charge one may\ncalculate the electron-phonon coupling constants from O(1) solutions of the\nSchrodinger equation. We show that Janak's theorem means that this procedure is\nexact within the density functional formalism. We demonstrate that the O(1)\napproach produces numerically accurate results by calculating the\nelectron-phonon coupling constants for a series of molecules ranging in size\nfrom H_2 to C_60. We use our approach to introduce a computationally fast\napproximation for the adiabatic ionisation potentials and electron affinities\nwhich is shown to be accurate for large molecules. We also show that our\napproach allows for the calculation isotope effects in O(0) time and discuss\nthe deuteration driven Mott transition in kappa-(BEDT-TTF)_2Cu[N(CN)_2]Br."
    },
    {
        "anchor": "Role of Conduction Electrons in the ortho-KC$_{60}$ Polymer: We present first-principles band calculations as well as structural\noptimization of the orthorhombic K$_1$C$_{60}$ polymerized phase. We found\nthree-dimensional inter-fullerene bonding/anti-bonding characters consisting of\n$t_{1u}$ molecular orbitals with $p$-like symmetry in the conduction bands. The\nformation of the four-membered ring connecting the fullerenes lifts the $p_x$\nband from the continuous $p_y$-$p_z$ band, where the z-axis is parallel to the\nchain. The asymmetry between $p_x$ and $p_y$ may play an important role in\nbinding the chains with the rotational configuration proposed by Stephens et\nal.",
        "positive": "Giant electromechanical response from defective non-ferroelectric\n  epitaxial BaTiO3 integrated on Si 100: Lead free, silicon compatible materials showing large electromechanical\nresponses comparable to, or better than conventional relaxor ferroelectrics,\nare desirable for various nanoelectromechanical devices and applications.\nDefect-engineered electrostriction has recently been gaining popularity to\nobtain enhanced electromechanical responses at sub 100 Hz frequencies. Here, we\nreport record values of electrostrictive strain coefficients (M31) at\nfrequencies as large as 5 kHz (1.04 x 10-14 m2 per V2 at 1 kHz, and 3.87 x\n10-15 m2 per V2 at 5 kHz) using A-site and oxygen-deficient barium titanate\nthin-films, epitaxially integrated onto Si. The effect is robust and retained\neven after cycling the devices >5000 times. Our perovskite films are\nnon-ferroelectric, exhibit a different symmetry compared to stoichiometric\nBaTiO3 and are characterized by twin boundaries and nano polar-like regions. We\nshow that the dielectric relaxation arising from the defect-induced features\ncorrelates very well with the observed giant electrostrictive response. These\nfilms show large coefficient of thermal expansion (2.36 x 10-5/K), which along\nwith the giant M31 implies a considerable increase in the lattice anharmonicity\ninduced by the defects. Our work provides a crucial step forward towards\nformulating guidelines to engineer large electromechanical responses even at\nhigher frequencies in lead-free thin films."
    },
    {
        "anchor": "Lattice Transformation from 2-D to Quasi 1-D and Phonon Properties of\n  Exfoliated ZrS2 and ZrSe2: We investigate the thermal properties of these Zirconium based materials\nusing confocal Raman spectroscopy. We observed 2 different and distinctive\nRaman signatures for exfoliated ZrX2 (where X = S or Se). These Raman modes\ngenerally depend on the shape of the exfoliated nanosheets, regardless of the\nincident laser polarization. These 2 shapes are divided into 2D- ZrX2 and quasi\n1D- ZrX2. For 2D- ZrX2, Raman modes are in alignment with those reported in\nliterature. However, for quasi 1D-ZrX2, we show that Raman modes are identical\nto exfoliated ZrX3 nanosheets, indicating a major lattice transformation from\n2D to quasi-1D. We also measure thermal properties of each resonant Raman mode\nfor each ZrX2 shape. Based on our measurements, most Raman modes exhibit a\nlinear downshift dependence with temperature. However, for ZrS2, we see an\nupshift (blueshift) with temperature for A1g mode, which is attributed to\nnon-harmonic effects caused by dipolar coupling with IR-active modes. Moreover,\nthe observed temperature dependence coefficient for some phonon modes of quasi\n1D-ZrX2 differ dramatically, which can be caused by the quasi 1D lattice.\nFinally, we measure phonon dynamics under optical heating for each of 2D-ZrX2\nand quasi 1D-ZrX2 and show phonon confinement in quasi 1D-ZrX2 nanosheets. We\nextract the thermal conductivity and the interfacial thermal conductance for\neach of 2D-ZrX2 and quasi 1D-ZrX2 nanosheets. Our calculations indicate lower\ninterfacial thermal conductance for quasi 1D-ZrX2 compared to 2D-ZrX2, which\ncan be attributed to the phonon confinement in 1D. Based on our model, we show\nlow thermal conductivity for all ZrX2 nanosheets. Our results demonstrate\nexceptional thermal properties for ZrX2 materials, making them ideal for future\nthermal management strategies and thermoelectric device applications.",
        "positive": "A Pseudo-Two-Dimensional (P2D) Model for FeS2 Conversion Cathode\n  Batteries: Conversion cathode materials are gaining interest for secondary batteries due\nto their high theoretical energy and power density. However, practical\napplication as a secondary battery material is currently limited by practical\nissues such as poor cyclability. To better understand these materials, we have\ndeveloped a pseudo-two-dimensional model for conversion cathodes. We apply this\nmodel to FeS2 - a material that undergoes intercalation followed by conversion\nduring discharge. The model is derived from the half-cell Doyle-Fuller-Newman\nmodel with additional loss terms added to reflect the converted shell\nresistance as the reaction progresses. We also account for polydisperse active\nmaterial particles by incorporating a variable active surface area and\neffective particle radius. Using the model, we show that the leading loss\nmechanisms for FeS2 are associated with solid-state diffusion and electrical\ntransport limitations through the converted shell material. The polydisperse\nsimulations are also compared to a monodisperse system, and we show that\npolydispersity has very little effect on the intercalation behavior yet leads\nto capacity loss during the conversion reaction. We provide the code as an\nopen-source Python Battery Mathematical Modelling (PyBaMM) model that can be\nused to identify performance limitations for other conversion cathode\nmaterials."
    },
    {
        "anchor": "Pressure-Induced Insulator-Metal Transition in Silicon Telluride from\n  First-Principles Calculations: Silicon telluride (Si2Te3) is a two-dimensional semiconductor with unique\nstructural properties due to the size contrast between Si and Te atoms. A\nrecent experiment shows that the material turns metallic under hydrostatic\npressure, while the lattice structure of the metallic phase remains to be\nidentified. In this paper, we propose two metallic phases, M1 and M2, of Si2Te3\nusing the evolution algorithm and first-principles density functional theory\n(DFT) calculations. Unlike the presence of Si-Si dimers in the semiconducting\n(SC) phase, both M1 and M2 phases have individual Si atoms, which play\nimportant roles in the metallicity. Analysis of structural properties,\nelectronic properties, dynamical as well as thermal stability is performed. The\nenergies of these new structures are compared with the SC phase under the\nsubsequent hydrostatic pressure up to 12 GPa. The results show that M1 and M2\nphases have lower energies under high pressure, thus elucidating the appearance\nof the metallic phase of Si2Te3. In addition, the external pressure causes the\nSC phase to have an indirect-direct-indirect bandgap transition. Analysis of\nRaman spectra of the SC phase at a different pressure shows the shifting of the\nmajor Raman peaks, and finally disappearing confirms the phase transition. The\nresults are in good agreement with the experimental observations. The\nunderstanding of the insulator-metal phase transition increases the potential\nusefulness of the material system.",
        "positive": "Fracture size effects from disordered lattice models: We study size effects in the fracture strength of notched disordered samples\nusing numerical simulations of lattice models for fracture. In particular, we\nconsider the random fuse model, the random spring model and the random beam\nmodel, which all give similar results. These allow us to establish and\nunderstand the crossover between a regime controlled by disorder-induced\nstatistical effects and a stress-concentration controlled regime ruled by\nfracture mechanics. The crossover is described by a scaling law that accounts\nfor the presence of fracture process zone which we quantify by averaging over\nseveral disordered configurations of the model. The models allow to study the\ndevelopment of the fracture process zone as the load is increased and to\nexpress this in terms of crack resistance (R-curve)."
    },
    {
        "anchor": "Inter-adsorbate forces and coherent scattering in helium spin-echo\n  experiments: In studies of dynamical systems, helium atoms scatter coherently from an\nensemble of adsorbates as they diffuse on the surface. The results give\ninformation on the co-operative behaviour of interacting adsorbates and thus\ninclude the effects of both adsorbate-substrate and adsorbate-adsorbate\ninteractions. Here, we discuss a method to disentangle the effects of\ninteractions between adsorbates from those with the substrate. The result gives\nan approximation to observations that would be obtained if the scattering was\nincoherent. Information from the experiment can therefore be used to\ndistinguish more clearly between long-range inter-adsorbate forces and the\nshort range effects arising from the local lattice potential and associated\nthermal excitations. The method is discussed in the context of a system with\nstrong inter-adsorbate interactions, sodium atoms diffusing on a copper (111)\nsurface.",
        "positive": "Theoretical prediction of magnetic and noncentrosymmetric Weyl fermion\n  semimetal states in the R-Al-X family of compounds (R=rare earth,\n  Al=aluminium, X=Si, Ge): Weyl semimetals are novel topological conductors that host Weyl fermions as\nemergent quasiparticles. While the Weyl fermions in high-energy physics are\nstrictly defined as the massless solution of the Dirac equation and uniquely\nfixed by Lorentz symmetry, there is no such constraint for a topological metal\nin general. Specifically, the Weyl quasiparticles can arise by breaking either\nthe space-inversion ($\\mathcal{I}$) or time-reversal ($\\mathcal{T}$) symmetry.\nThey can either respect Lorentz symmetry (type-I) or strongly violate it\n(type-II). To date, different types of Weyl fermions have been predicted to\noccur only in different classes of materials. In this paper, we present a\nsignificant materials breakthrough by identifying a large class of Weyl\nmaterials in the RAlX (R=Rare earth, Al, X=Ge, Si) family that can realize all\ndifferent types of emergent Weyl fermions ($\\mathcal{I}$-breaking,\n$\\mathcal{T}$-breaking, type-I or type-II), depending on a suitable choice of\nthe rare earth elements. Specifically, RAlX can be ferromagnetic, nonmagnetic\nor antiferromagnetic and the electronic band topology and topological nature of\nthe Weyl fermions can be tuned. The unparalleled tunability and the large\nnumber of compounds make the RAlX family of compounds a unique Weyl semimetal\nclass for exploring the wide-ranging topological phenomena associated with\ndifferent types of emergent Weyl fermions in transport, spectroscopic and\ndevice-based experiments."
    },
    {
        "anchor": "Simulation of the enhanced Curie temperature in Mn_5Ge_3C_x compounds: Mn_5Ge_3C_x films with x>0.5 were experimentally shown to exhibit a strongly\nenhanced Curie temperature T_C compared to Mn_5Ge_3. In this letter we present\nthe results of our first principles calculations within Green's function\napproach, focusing on the effect of carbon doping on the electronic and\nmagnetic properties of the Mn_5Ge_3. The calculated exchange coupling constants\nrevealed an enhancement of the ferromagnetic Mn-Mn interactions mediated by\ncarbon. The essentially increased T_C in Mn_5Ge_3C is well reproduced in our\nMonte Carlo simulations and together with the decrease of the total\nmagnetisation is found to be predominantly of an electronic nature.",
        "positive": "Steadfast perpendicular exchange coupling in an ultrathin CoO/PtFe\n  double-layer: strain and spin orientation: We report on the exchange coupling and magnetic properties of a strained\nultrathin CoO/PtFe double-layer with perpendicular magnetic anisotropy. The\ncobalt oxide growth by reactive molecular beam epitaxy on a Pt-terminated\nPtFe/Pt(001) surface gives rise to an hexagonal surface and a monoclinic\ndistorted CoO 3nm film at room temperature. This distorted ultrathin CoO layer\ncouples with the PtFe(001) layer establishing a robust perpendicular exchange\nbias shift. Soft x-ray absorption spectroscopy provides a full description of\nthe spin orientations in the CoO/PtFe doublelayer. The exchange bias shift is\npreserved up to the Neel antiferromagnetic ordering temperature of TN=293 K.\nThis unique example of selfsame value for blocking and ordering temperatures,\nyet identical to the bulk ordering temperature, is likely related to the\noriginal strain induced distortion and strengthened interaction between the two\nwell-ordered spin layers."
    },
    {
        "anchor": "Optical conductivity spectra of the rattling phonons and charge carriers\n  in type-VIII clathrate Ba$_8$Ga$_{16}$Sn$_{30}$: We have investigated optical conductivity spectra of $n$- and $p$-type\nBa$_8$Ga $_{16}$Sn$_{30}$ ($\\alpha$-BGS) with type-VIII clathrate structure, at\ntemperatures from 296\\,K down to 6\\,K with a terahertz time-domain spectrometer\n(0.2\\,-\\,2.5\\,THz). The continuous spectra contributed from charge carriers are\ndispersive in this frequency range and also temperature- and carrier\ntype-dependent. The Drude-Smith model taking multiple-scatterings of charge\ncarriers into account well reproduces those data. The relaxation rate of the\n$n$-type carriers decreases more sharply than that in the $p$-type material,\nsuggesting that a stronger electron-phonon interaction may exist in the\n$n$-type than in the $p$-type. On the other hand, the localized infrared-active\nmodes observed at 1.3\\,THz and 1.7\\,THz, identified as the rattling phonons of\nthe Ba$^{2+}$ ion's quasi-on-center vibrations, become soft and broad\nsignificantly with decreasing temperature as well as observed in type-I BGS and\nBGG (Ba$_8$Ga$_{16}$Ge$_{30}$) clathrates. The softening in the $n$-type is\nsmaller by about 30% than in the $p$-type, whereas the linewidth brodening is\nalmost the same independently on the carrier type. The difference in the\nsoftening is discussed with a scenario where the interaction of rattling\nphonons with carriers can modify the anharmonic potential of the guest ions.\nThe anomalous broadening at low temepratures is also discussed by the\nimpurity-scattering model presented for a rattling-phonon system strongly\nhybridized with acoustic cage phonons.",
        "positive": "Dynamic Disorder in Negative Thermal Expansion Compound Zn(CN)2: Dynamical disorder in negative thermal expansion compound Zn(CN)2 is\ninvestigated by quasielastic neutron scattering technique in the temperature\nrange 170-320 K. Significant quasielastic broadening is observed above the\nphase transition temperature of about 250 K, however no broadening is observed\nat 220 K and below. Data at high temperatures are analyzed assuming the CN\nreorientation. Characteristic time associated with the CN orientation is\nestimated as 16 ps and 11 ps at 270 and 320 K respectively."
    },
    {
        "anchor": "Effect of Electron-Phonon Coupling on Thermal Transport across\n  Metal-Nonmetal Interface - A Second Look: The effect of electron-phonon (e-ph) coupling on thermal transport across\nmetal-nonmetal interfaces is yet to be completely understood. In this paper, we\nuse a series of molecular dynamics (MD) simulations with e-ph coupling effect\nincluded by Langevin dynamics to calculate the thermal conductance at a model\nmetal-nonmetal interface. It is found that while e-ph coupling can present\nadditional thermal resistance on top of the phonon-phonon thermal resistance,\nit can also make the phonon-phonon thermal conductance larger than the pure\nphonon transport case. This is because the e-ph interaction can disturb the\nphonon subsystem and enhance the energy communication between different phonon\nmodes inside the metal. This facilitates redistributing phonon energy into\nmodes that can more easily transfer energy across the interfaces. Compared to\nthe pure phonon thermal conduction, the total thermal conductance with e-ph\ncoupling effect can become either smaller or larger depending on the coupling\nfactor. This result helps clarify the role of e-ph coupling in thermal\ntransport across metal-nonmetal interface.",
        "positive": "Arrhenius Crossover Temperature of Glass-Forming Liquids Predicted by an\n  Artificial Neural Network: The Arrhenius crossover temperature, $T_{A}$, corresponds to a thermodynamic\nstate wherein the atomistic dynamics of a liquid becomes heterogeneous and\ncooperative; and the activation barrier of diffusion dynamics becomes\ntemperature-dependent at temperatures below $T_{A}$. The theoretical estimation\nof this temperature is difficult for some types of materials, especially\nsilicates and borates. In these materials, self-diffusion as a function of the\ntemperature $T$ is reproduced by the Arrhenius law, where the activation\nbarrier practically independent on the temperature $T$. The purpose of the\npresent work was to establish the relationship between the Arrhenius crossover\ntemperature $T_{A}$ and the physical properties of liquids directly related to\ntheir glass-forming ability. Using a machine learning model, the crossover\ntemperature $T_{A}$ was calculated for silicates, borates, organic compounds\nand metal melts of various compositions. The empirical values of the glass\ntransition temperature $T_{g}$, the melting temperature $T_{m}$, the ratio of\nthese temperatures $T_{g}/T_{m}$ and the fragility index $m$ were applied as\ninput parameters. It has been established that the temperatures $T_{g}$ and\n$T_{m}$ are significant parameters, whereas their ratio $T_{g}/T_{m}$ and the\nfragility index $m$ do not correlate much with the temperature $T_{A}$. An\nimportant result of the present work is the analytical equation relating the\ntemperatures $T_{g}$, $T_{m}$ and $T_{A}$, and that, from the algebraic point\nof view, is the equation for a second-order curved surface. It was shown that\nthis equation allows one to correctly estimate the temperature $T_{A}$ for a\nlarge class of materials, regardless of their compositions and glass-forming\nabilities."
    },
    {
        "anchor": "Data-analysis software framework 2DMAT and its application to\n  experimental measurements for two-dimensional material structures: An open-source data-analysis framework 2DMAT has been developed for\nexperimental measurements of two-dimensional material structures. 2DMAT offers\nfive analysis methods: (i) Nelder-Mead optimization, (ii) grid search, (iii)\nBayesian optimization, (iv) replica exchange Monte Carlo method, and (v)\npopulation-annealing Monte Carlo method. Methods (ii) through (v) are\nimplemented by parallel computation,which is efficient not only for personal\ncomputers but also for supercomputers.The current version of 2DMAT is\napplicable to total-reflection high-energy positron diffraction (TRHEPD),\nsurface X-ray diffraction (SXRD), and low-energy electron diffraction (LEED)\nexperiments by installing corresponding forward problem solvers that generate\ndiffraction intensity data from a given dataset of the atomic positions. The\nanalysis methods are general and can be applied also to other experiments and\nproblems.",
        "positive": "Influence of interphase anisotropy on lamellar eutectic growth patterns: It is well documented in many experiments that crystallographic effects play\nan important role in the generation of two-phase patterns during the\nsolidification of eutectic alloys. In particular, in lamellar composites, large\npatches of perfectly aligned lamellae are frequently observed. Moreover, the\ngrowth direction of the lamellae often markedly differs from the direction of\nthe temperature gradient (the lamellae are tilted with respect to the main\ngrowth direction). Both of these effects cannot be explained either by the\nstandard theory or the available numerical models of eutectic growth, which all\nassume the interfaces to be isotropic. We have developed a phase-field model in\nwhich the anisotropy of each interface (solid-liquid and solid-solid) can be\nseparately controlled, and we have investigated the effect of interface\nanisotropy on the growth dynamics. We have found that anisotropy of the\nsolid-solid interphase boundary free energy dramatically alters the growth\ndynamics. Tilted lamellae result from the modified equilibrium condition at the\ntriple lines, in good agreement with a theoretical conjecture proposed\nrecently. In three dimensions, the interphase boundaries tend to align with\ndirections of minimal energy. We have also performed simulations in which two\ngrains with different anisotropies are in competition. In all cases, the grain\ncontaining the boundaries with the lowest energies was selected after a\ntransient. These results shed new light on the selection of growth patterns in\neutectic solidification."
    },
    {
        "anchor": "Pressure-induced softening as a common feature of framework structures\n  that have negative thermal expansion: Results of a series of molecular dynamics simulations of cubic siliceous\nzeolites suggest that pressure-induced softening -- the phenomenon in which a\nmaterial becomes progressively more compressible under pressure -- is likely to\nbe a common feature of framework materials that show negative thermal\nexpansion. The correlation between the negative thermal expansion and the\npressure-induced softening is investigated on the basis of thermodynamics.",
        "positive": "Super-Resolution Nanolithography of Two-Dimensional Materials by\n  Anisotropic Etching: Nanostructuring allows altering of the electronic and photonic properties of\ntwo-dimensional (2D) materials. The efficiency, flexibility, and convenience of\ntop-down lithography processes are however compromised by nm-scale edge\nroughness and resolution variability issues, which especially affects the\nperformance of 2D materials. Here we study how dry anisotropic etching of\nmultilayer 2D materials with sulfur hexafluoride (SF6) may overcome some of\nthese issues, showing results for hexagonal boron nitride (hBN), tungsten\ndisulfide (WS2), tungsten diselenide (WSe2), molybdenum disulfide (MoS2),\nmolybdenum ditelluride (MoTe2). Scanning and transmission electron microscopy\nreveal that etching leads to anisotropic hexagonal features in the studied\ntransition metal dichalcogenides, with the relative degree of anisotropy ranked\nas: WS2 > WSe2 > MoTe2 / MoS2. Etched holes are terminated by zigzag edges\nwhile etched dots (protrusions) are terminated by armchair edges. This can be\nexplained by Wulff constructions, taking the relative stabilities of the edges\nand the AA stacking order into account. Patterns in WS2 are transferred to an\nunderlying graphite layer, demonstrating a possible use for creating sub-10 nm\nfeatures. In contrast, multilayer hBN exhibits no lateral anisotropy, but shows\nconsistent vertical etch angles, independent of crystal orientation. This is\nused to create super-resolution lithographic patterns with ultra-sharp corners\nat the base of the hBN crystal, which are transferred into an underlying\ngraphite crystal. We find that the anisotropic SF6 reactive ion etching process\nmakes it possible to downsize nanostructures to obtain smooth edges, sharp\ncorners, and feature sizes significantly below the resolution limit of electron\nbeam lithography. The nanostructured 2D materials can be used themselves or as\netch-masks to pattern other nanomaterials."
    },
    {
        "anchor": "Enhancement of high-order harmonic generation in graphene by\n  mid-infrared and terahertz fields: We theoretically investigate high-order harmonic generation (HHG) in graphene\nunder mid-infrared (MIR) and terahertz (THz) fields based on a quantum master\nequation. Numerical simulations show that MIR-induced HHG in graphene can be\nenhanced by a factor of 10 for fifth harmonic and a factor of 25 for seventh\nharmonic under a THz field with a peak strength of 0.5 MV/cm by optimizing the\nrelative angle between the MIR and THz fields. To identify the origin of this\nenhancement, we compare the fully dynamical calculations with a simple\nthermodynamic model and a nonequilibrium population model. The analysis shows\nthat the enhancement of the high-order harmonics mainly results from a coherent\ncoupling between MIR- and THz-induced transitions that goes beyond a simple\nTHz-induced population contribution.",
        "positive": "Predicting the growth rate of helium bubbles in metal tritide: Helium bubbles nucleation and growth in metals or metal tritide is a\nlong-standing problem attracting considerable attention in nuclear industry but\nthe mechanism remains indistinct and predicting the growth rate of helium\nbubble is inexistence still up to new. Here, the rate of helium bubbles\nnucleation and growth in metal tritide is developed based on a dynamical model,\nwhich describes the diameter of helium bubbles increasing linearly as t**(1/3)\nin titanium tritide at room temperature, agreeing quite well with the\nexperimental phenomenon. The way of reducing storage temperature from 300 to\n225 K or increasing the helium atoms diffusion barrier from 0.81 to 1.1 eV can\neffectively restrain bubbles growth and prolong lifetime of titanium tritide\nmore than 4 times, which provides a useful reference to relevant experiment\nexploration and applications. This model also can be used to predict lifetime\nof new tritium-storage materials and plasma facing materials in nuclear\nindustry."
    },
    {
        "anchor": "Dislocation dynamics simulations with climb: kinetics of dislocation\n  loop coarsening controlled by bulk diffusion: Dislocation climb mobilities, assuming vacancy bulk diffusion, are derived\nand implemented in dislocation dynamics simulations to study the coarsening of\nvacancy prismatic loops in fcc metals. When loops cannot glide, the comparison\nof the simulations with a coarsening model based on the line tension\napproximation shows a good agreement. Dislocation dynamics simulations with\nboth glide and climb are then performed. Allowing for glide of the loops along\ntheir prismatic cylinders leads to faster coarsening kinetics, as direct\ncoalescence of the loops is now possible.",
        "positive": "Noncollinear ferrielectricity and morphotropic phase boundary in GeS\n  monolayer: Two-dimensional polarity is intriguing but remains in the early stage. Here a\nstructural evolution diagram is established for GeS monolayer, which leads a\nnoncollinear ferrielectric $\\delta$-phase energetically as stable as the\nferroelectric $\\alpha$-phase. Its ferrielectricity is induced by the phonon\nfrustration, i.e., the competition between ferroelectric and antiferroelectric\nmodes, providing more routes to tune its polarity. Besides its prominent\nproperties like large band gap, large polarization, and high Curie temperature,\nmore interestingly, the morphotropic phase boundary between $\\alpha$- and\n$\\delta$-phases is highly possible, which is crucial to obtain giant\npiezoelectricity for lead-free applications."
    },
    {
        "anchor": "DNA-decorated carbon nanotubes for chemical sensing: We demonstrate a new, versatile class of nanoscale chemical sensors based on\nsingle-stranded DNA (ss-DNA) as the chemical sensors recognition site and\nsingle-walled carbon nanotube field effect transistors (swCN-FET) as the\nelectronic read-out component. swCN-FETs with a nanoscale coating of ss-DNA\nrespond to gas odors that do not cause a detectable conductivity change in bare\ndevices. Responses of ss-DNA/swCN-FETs differ in sign and magnitude for\ndifferent gases, and can be tuned by choosing the base sequence of the ss-DNA.\nss-DNA/swCN-FET sensors detect a variety of odors, with rapid response and\nrecovery times on the scale of seconds. The sensor surface is\nself-regenerating: samples maintain a constant response with no need for sensor\nrefreshing through at least 50 gas exposure cycles. This very remarkable set of\nattributes makes sensors based on ss-DNA decorated nanotubes very promising for\n\"electronic nose\" and \"electronic tongue\" applications ranging from homeland\nsecurity to disease diagnosis.",
        "positive": "Quantitative Analysis of Photo-Thermal Stability of CdSe/CdS Core-Shell\n  Nanocrystals: We report here investigations on the instability in luminescence of bare\n(TOPO-stabilized) and CdS- capped CdSe particles under infrared radiation.\nDuring photo-thermal annealing the formation of oxide layers on the surfaces of\nthe particles create defect states. Consequently there is a reduction in\nparticle size. These two effects control the light output from the samples. We\nmake a quantitative comparison of the stability of bare CdSe and core-shell\ntype CdSe-CdS particles under photo-annealing. Using diffusion theory, we show\nthat the volume of the oxide layer, adhered to the crystallites, play a\ndominant role in controlling the luminosity of the particles."
    },
    {
        "anchor": "Prediction of a large-gap and switchable Kane-Mele quantum spin Hall\n  insulator: Fundamental research and technological applications of topological insulators\nare hindered by the rarity of materials exhibiting a robust topologically\nnon-trivial phase, especially in two dimensions. Here, by means of extensive\nfirst-principles calculations, we propose a novel quantum spin Hall insulator\nwith a sizeable band gap of $\\sim$0.5 eV that is a monolayer of Jacutingaite, a\nnaturally occurring layered mineral first discovered in 2008 in Brazil and\nrecently synthesised. This system realises the paradigmatic Kane-Mele model for\nquantum spin Hall insulators in a potentially exfoliable two-dimensional\nmonolayer, with helical edge states that are robust and that can be manipulated\nexploiting a unique strong interplay between spin-orbit coupling,\ncrystal-symmetry breaking and dielectric response.",
        "positive": "Glass-forming photoactive cholesteric materials doped by quantum dots:\n  phototunable circularly-polarized emission: A novel glass-forming photoactive cholesteric materials doped by quantum dots\nwere prepared and studied. The possibility of phototuning of\ncircularly-polarized emission was demonstrated."
    },
    {
        "anchor": "Stable Charged Antiparallel Domain Walls in Hyperferroelectrics: Charge-neutral 180$^\\circ$ domain walls that separate domains of antiparallel\npolarization directions are common structural topological defects in\nferroelectrics. In normal ferroelectrics, charged 180$^\\circ$ domain walls\nrunning perpendicular to the polarization directions are highly energetically\nunfavorable because of the depolarization field and are difficult to stabilize.\nWe explore both neutral and charged 180$^\\circ$ domain walls in\nhyperferroelectrics, a class of proper ferroelectrics with persistent\npolarization in the presence of a depolarization field, using density\nfunctional theory. We obtain zero temperature equilibrium structures of\nhead-to-head and tail-to-tail walls in recently discovered $ABC$-type hexagonal\nhyperferroelectrics. Charged domain walls can also be stabilized in canonical\nferroelectrics represented by LiNbO$_3$ without any dopants, defects or\nmechanical clamping. First-principles electronic structure calculations show\nthat charged domain walls can reduce and even close the band gap of host\nmaterials and support quasi-two-dimensional electron(hole) gas with enhanced\nelectrical conductivity.",
        "positive": "Absence of Induced Ferromagnetism in Epitaxial Uranium Dioxide Thin\n  Films: Recently, Sharma et al. [Adv. Sci. 9, 2203473 (2022)] claimed that thin films\n(around 20 nm) of UO2 deposited on perovskite substrates exhibit strongly\nenhanced paramagnetism (called induced ferromagnetism by the authors). Moments\nof up to 3 Bohr magneton/U atom were claimed in magnetic fields of 6 T. We have\nreproduced such films and, after characterisation, have examined them with\nX-ray circular magnetic dichroism (XMCD) at the uranium M edges, a technique\nthat is element specific. We do not confirm the published results. We find a\nsmall increase, as compared to the bulk, in the magnetic susceptibility of UO2\nin such films, but the magnetisation versus field curves, measured by XMCD, are\nlinear with field and there is no indication of any ferromagnetism. The absence\nof any anomaly around 30 K (the antiferromagnetic ordering temperature of bulk\nUO2) in the XMCD signal suggests the films do not order magnetically."
    },
    {
        "anchor": "First-principles modeling of the polycyclic aromatic hydrocarbons\n  reduction: Density functional theory modelling of the reduction of realistic\nnanographene molecules (C42H18, C48H18 and C60H24) by molecular hydrogen\nevidences for the presence of limits in the hydrogenation process. These limits\ncaused the contentions between three-fold symmetry of polycyclic aromatic\nhydrocarbon molecules and two-fold symmetry of adsorbed hydrogen pairs.\nIncrease of the binding energy between nanographenes during reduction is also\ndiscussed as possible cause of the experimentally observed limited\nhydrogenation of studied nanographenes.",
        "positive": "Self-trapped states and the related luminescence in PbCl$_2$ crystals: We have comprehensively investigated localized states of photoinduced\nelectron-hole pairs with electron-spin-resonance technique and\nphotoluminescence (PL) in a wide temperature range of 5-200 K. At low\ntemperatures below 70 K, holes localize on Pb$^{2+}$ ions and form\nself-trapping hole centers of Pb$^{3+}$. The holes transfer to other trapping\ncenters above 70 K. On the other hand, electrons localize on two Pb$^{2+}$ ions\nat higher than 50 K and form self-trapping electron centers of Pb$_2$$^{3+}$.\n  From the thermal stability of the localized states and PL, we clarify that\nblue-green PL band at 2.50 eV is closely related to the self-trapped holes."
    },
    {
        "anchor": "Doping-induced spin-orbit splitting in Bi-doped ZnO nanowires: Our predictions, based on density-functional calculations, reveal that\nsurface doping of ZnO nanowires with Bi leads to a linear-in-$k$ splitting of\nthe conduction-band states, through spin-orbit interaction, due to the lowering\nof the symmetry in the presence of the dopant. This finding implies that spin\npolarization of the conduction electrons in Bi-doped ZnO nanowires could be\ncontrolled with applied electric (as opposed to magnetic) fields, making them\ncandidate materials for spin-orbitronic applications. Our findings also show\nthat the degree of spin splitting could be tuned by adjusting the dopant\nconcentration. Defect calculations and ab initio molecular dynamics simulations\nindicate that stable doping configurations exhibiting the foregoing\nlinear-in-$k$ splitting could be realized under reasonable thermodynamic\nconditions.",
        "positive": "Structural and dynamic properties of soda-lime-silica in the liquid\n  phase: Soda-lime-silica is a glassy system of strong industrial interest. In order\nto characterize its liquid state properties, we performed molecular dynamics\nsimulations employing an aspherical ion model that includes atomic polarization\nand deformation effects. They allowed to study the structure and diffusion\nproperties of the system at temperatures ranging from 1400 to 3000 K. We show\nthat Na$^+$ and Ca$^{2+}$ ions adopt a different structural organization within\nthe silica network, with Ca$^{2+}$ ions having a greater affinity for\nnon-bridging oxygens than Na$^+$. We further link this structural behavior to\ntheir different diffusivities, suggesting that escaping from the first oxygen\ncoordination shell is the limiting step for the diffusion. Na$^+$ diffuses\nfaster than Ca$^{2+}$ because it is bonded to a smaller number of non-bridging\noxygens. The formed ionic bonds are also less strong in the case of Na$^+$."
    },
    {
        "anchor": "Quantitative calculations of the excitonic energy spectra of\n  semiconducting single-walled carbon nanotubes within a $\u03c0$-electron model: Using Coulomb correlation parameters appropriate for $\\pi$-conjugated\npolymers (PCPs), and a nearest neighbor hopping integral that is arrived at by\nfitting the energy spectra of three zigzag semiconducting single-walled carbon\nnanotubes (S-SWCNTs), we are able to determine quantitatively the exciton\nenergies and exciton binding energies of 29 S-SWCNTs within a semiempirical\n$\\pi$-electron Hamiltonian that has been widely used for PCPs. Our work\nestablishes the existence of a deep and fundamental relationship between PCPs\nand S-SWCNTs.",
        "positive": "Theory of magnetic spin and orbital Hall and Nernst effects in bulk\n  ferromagnets: The magnetic spin Hall effect (MSHE) is an anomalous charge-to-spin\nconversion phenomenon which occurs in ferromagnetic materials. In contrast to\nthe conventional spin Hall effect (SHE), being a time-reversal even effect, the\nmagnetic counterpart is time-reversal odd. In this work, we use ab initio\ncalculations to investigate the MSHE for the bulk ferromagnets Fe, Co, and Ni.\nThe magnitudes of the MSHE of Fe and Co are comparable to those of the SHE, but\nthe MSHE is strongly dependent on the electron lifetime and the MSHE and SHE\ncan moreover have opposite signs. For Ni the MSHE is smaller than the SHE, but\nin general, the MSHE cannot be ignored for spin-orbit torques. Considering a\ncharge current we analyze how both the MSHE and SHE contribute to a total Hall\nangle. We extend our analysis of the MSHE to its orbital counterpart, that is,\nthe magnetic orbital Hall effect (MOHE), for which we show that the MOHE is in\ngeneral smaller than the orbital Hall effect (OHE). We compute furthermore the\nthermal analogs, i.e., the spin and orbital Nernst effects, and their magnetic\ncounterparts. Here our calculations show that the magnetic spin and orbital\nNernst effects of Ni are substantially larger than those of Fe and Co."
    },
    {
        "anchor": "Electrophoretic mobilities of dissolved polyelectrolyte charging agent\n  and suspended non-colloidal titanium during electrophoretic deposition: Coarse (<=20 micron) titanium particles were deposited on low-carbon steel\nsubstrates by cathodic electrophoretic deposition (EPD) with ethanol as\nsuspension medium and poly(diallyldimethylammonium chloride) (PDADMAC) as\npolymeric charging agent. The preceding data demonstrated that Ti particles of\n~1-12 micron size, electrosterically modified by the PDADMAC charging agent,\nacted effectively as colloidal particles during EPD. Owing to the non-colloidal\nnature of the particles and the stabilization of the Ti particles by\nelectrosteric forces, the relevance of the zeta potential is questionable, so\nthe more fundamental parameter of electrophoretic mobility was used. A key\nfinding from the present work is the importance of assessing the\nelectrophoretic mobilities of both the suspensions and solutions since the\nlatter, which normally is overlooked, plays a critical role in the ability to\ninterpret the results meaningfully. Further, algebraic uncoupling of these data\nplus determination of the deposit yield as a function of charging agent\naddition allow discrimination between the three main mechanistic stages of the\nelectrokinetics of the process, which are: (1) surface saturation; (2)\ncompression of the diffuse layer, growth of polymer-rich layer, and/or\ncompetition between the mobility of Ti and PDADMAC; and (3) little or no\ndecrease in electrophoretic mobility of Ti, establishment of polymer-rich\nlayer, and/or dominance of the mobility of the PDADMAC over that of Ti.",
        "positive": "Autonomous Optimization of an Organic Solar Cell in a 4-dimensional\n  Parameter Space: Optimizing solution-processed organic solar cells is a complex task due to\nthe vast parameter space in organic photovoltaics (OPV). Classical Edisonian or\none-variable-at-a-time (OVAT) optimization approaches are laborious,\ntime-consuming, and may not find the optimal parameter set in multidimensional\ndesign spaces. To tackle this problem, we demonstrate here for the first time\nartificial intelligence (AI) guided closed-loop autonomous optimization for\nfully functional organic solar cells. We empower our LineOne, an automated\nmaterials and device acceleration platform with a Bayesian Optimizer (BO) to\nenable autonomous operation for solving complex optimization problems without\nhuman interference. The system is able to fabricate and characterize complete\nOPV devices and navigate efficiently through the design space spanned by\ncomposition and processing parameters. In addition, a Gaussian Progress\nRegression (GPR) based early prediction model is employed to predict the\nefficiency of the cells from cheap proxy measurements, in our case, thin film\nabsorption spectra, which are analyzed using a spectral model based on physical\nproperties to generate microstructure features as input for the GPR. We\ndemonstrate our generic and complete autonomous approach by optimizing\ncomposition and processing conditions of a ternary OPV system (PM6:Y12:PC70BM)\nin a four-dimensional parameter space. We identify the best parameter set for\nour system and obtain a precise objective function over the whole parameter\nspace with a minimal number of samples. We demonstrate autonomous optimization\nof a complex opto-electronic device within 40 samples only, whereas an\nEdisonian approach would have required about 1000 samples. This raises an\nimportant discussion on the necessity of autonomous platforms to accelerate\nMaterial science."
    },
    {
        "anchor": "First principles modeling of oxygen adsorption on LaMnO3 (001) surface: We present and discuss the results of ab initio DFT plane-wave supercell\ncalculations of the atomic and molecular oxygen adsorption and diffusion on the\nLaMnO3 (001) surface which serves as a model material for a cathode of solid\noxide fuel cells. The dissociative adsorption of O2 molecules from the gas\nphase is energetically favorable on surface Mn ions even on a defect-free\nsurface. The surface migration energy for adsorbed O ions is found to be quite\nhigh, 1.6 eV. We predict that the adsorbed O atoms could penetrate into\nelectrode first plane when much more mobile surface oxygen vacancies (migration\nenergy of 0.69 eV) approach the O ions strongly bound to the surface Mn ions.\nAb initio thermodynamics predicts that at typical SOFC operation temperatures\n(~1200 K) the MnO2 (001) surface with adsorbed O atoms is the most stable in a\nvery wide range of oxygen gas pressures (above 10^2 atm).",
        "positive": "Electrical characterization of gadolinium oxide deposited by high\n  pressure sputtering with in situ plasma oxidation: In this work, we characterized gadolinium oxide films deposited on silicon by\nhigh pressure sputtering with a two-step process: first, we sputtered metallic\ngadolinium in an argon atmosphere and then, we performed an in-situ plasma\noxidation of the metallic layer previously deposited. By means of high\nresolution transmission electron microscopy, we can detect the oxidation degree\nof the metallic film. Under optimized deposition conditions, fully oxidized\nGd2O3 films are obtained. In addition, the capacitance and conductance as a\nfunction of gate voltage of Pt gated metal-insulator-semiconductor capacitors\nconfirm stable dielectric behavior of the fully oxidized films. The devices\nshow low gate leakage currents (1e5 A/cm2 at 1 V for 2.2 nm of equivalent oxide\nthickness), low interface trap density and an almost negligible hysteresis and\nfrequency dispersion."
    },
    {
        "anchor": "Yield conditions for deformation of amorphous polymer glasses: Shear yielding of glassy polymers is usually described in terms of the\npressure-dependent Tresca or von Mises yield criteria. We test these criteria\nagainst molecular dynamics simulations of deformation in amorphous polymer\nglasses under triaxial loading conditions that are difficult to realize in\nexperiments. Difficulties and ambiguities in extending several standard\ndefinitions of the yield point to triaxial loads are described. Two\ndefinitions, the maximum and offset octahedral stresses, are then used to\nevaluate the yield stress for a wide range of model parameters. In all cases,\nthe onset of shear is consistent with the pressure-modified von Mises\ncriterion, and the pressure coefficient is nearly independent of many\nparameters. Under triaxial tensile loading, the mode of failure changes to\ncavitation.",
        "positive": "Anomalous excitonic resonance Raman effects in few-layer MoS2: The resonance effects on the Raman spectra from 5 to 900 cm-1 of few-layer\nMoS2 thin films up to 14-layers were investigated by using six excitation\nenergies. For the main first-order Raman peaks, the intensity maximum occurs at\n~2.8 eV for single layer and at ~2.5 eV for few-layer MoS2, which correspond to\nthe band-gap energy. At the excitation energy of 1.96 eV, several anomalous\nbehaviors are observed. Many second-order peaks are anomalously enhanced even\nthough the main first-order peaks are not enhanced. In the low-frequency region\n(<100 cm-1), a broad peak centered at ~38 cm-1 and its second order peak at 76\ncm-1 appear for the excitation energy of 1.96 eV. These anomalous resonance\neffects are interpreted as being due to strong resonance with excitons or\nexciton-polaritons."
    },
    {
        "anchor": "A magnetic tight-binding model: correlations in ferromagnetic transition\n  metals: The estimation of correlations through approximations in an electronic\nmany-body calculation often leads to overestimated or underestimated physical\nproperties. But it is possible to better evaluate and understand the effect of\ncorrelations from the charge distribution and a screening effect due to a\ndelocalized s state. This provides an accurate description of the d-band\nmagnetism, unifying a localized and delocalized approach and giving approximate\nvalues of the band gap in the monoxides of ferromagnetic transition metals.\nFrom a tight-binding calculation, 1.3 eV for bcc iron, 1.5 eV for fcc cobalt\nand 2.1 eV for fcc nickel are found as Coulomb correlations correcting the\nmagnetic energies of a localized d-band approximation.",
        "positive": "Novel Numerical Methods for Measuring Distributions of Space Charge and\n  Electric Field in Solid Dielectrics with Deconvolution Algorithm: The deconvolution algorithm for measuring distribution of space charge under\ndc by the pressure wave propagation (PWP) method is studied in this paper. A\nnew Fredholm integral equation of first kind, including a space charge\ndistribution without a partial differential operator is presented. Numerical\nmethods based on Tikhonov regularization for solving this integral equation and\nthe original PWP equation are studied. Numerical simulation is studied for the\neffect of signal-to-noise ratio (SNR), and comparison with other algorithms is\ndiscussed. The numerical solution of an electric field distribution from\nmeasurements of a LDPE specimen is obtained successfully."
    },
    {
        "anchor": "Pressure-driven phase transformations and phase segregation in\n  ferrielectric CuInP$_2$S$_6$-In$_{4/3}$P$_2$S$_6$ self-assembled\n  heterostructures: Layered multi-ferroic materials exhibit a variety of functional properties\nthat can be tuned by varying the temperature and pressure. As-synthesized\nCuInP$_2$S$_6$ is a layered material that displays ferrielectric behavior at\nroom temperature. When synthesized with Cu deficiencies, CuInP$_2$S$_6$\nspontaneously phase segregates to form ferrielectric CuInP$_2$S$_6$ (CIPS) and\nparaelectric In$_{4/3}$P$_2$S$_6$ (IPS) domains in a two-dimensional\nself-assembled heterostructure. Here, we study the effect of hydrostatic\npressure on the structure of Cu-deficient CuInP$_2$S$_6$ by Raman spectroscopy\nmeasurements up to 20 GPa. Detailed analysis of the frequencies, intensities,\nand linewidths of the Raman peaks reveals four discontinuities in the spectra\naround 2, 10, 13 and 17 GPa. At ~2 GPa, we observe a structural transition\ninitiated by the diffusion of IPS domains, which culminates in a drastic\nreduction of the number of peaks around 10 GPa. We attribute this to a possible\nmonoclinic-trigonal phase transition at 10 GPa. At higher pressures (~ 13 GPa),\nsignificant increases in peak intensities and sharpening of the Raman peaks\nsuggest a bandgap-lowering and an isostructural electronic transition, with a\npossible onset of metallization at pressures above 17 GPa. When the pressure is\nreleased, the structure again phase-separates into two distinct chemical\ndomains within the same single crystalline framework -- however, these domains\nare much smaller in size than the as-synthesized material resulting in\nsuppression of ferroelectricity through nanoconfinement. Hydrostatic pressure\ncan thus be used to tune the electronic and ferrielectric properties of\nCu-deficient layered CuInP$_2$S$_6$.",
        "positive": "Nanowire-Intensified MEF in Hybrid Polymer-Plasmonic Electrospun\n  Filaments: Hybrid polymer-plasmonic nanostructures might combine high enhancement of\nlocalized fields from metal nanoparticles with light confinement and long-range\ntransport in subwavelength dielectric structures. Here we report on the complex\nbehavior of fluorophores coupling to Au nanoparticles within polymer nanowires,\nwhich features localized metal-enhanced fluorescence (MEF) with unique\ncharacteristics compared to conventional structures. The intensification effect\nwhen the particle is placed in the organic filaments is remarkably higher with\nrespect to thin films of comparable thickness, thus highlighting a specific,\nnanowire-related enhancement of MEF effects. A dependence on the confinement\nvolume in the dielectric nanowire is also evidenced, with MEF significantly\nincreasing upon reducing the wire diameter. These findings are rationalized by\nfinite element simulations, predicting a position-dependent enhancement of the\nquantum yield of fluorophores embedded in the fibers. Calculation of the\nensemble-averaged fluorescence enhancement unveils the possibility of strongly\nenhancing the overall emission intensity for structures with size twice the\ndiameter of the embedded metal particles. These new, hybrid fluorescent systems\nwith localized enhanced emission, as well as the general Nanowire-Intensified\nMEF effect associated to them, are highly relevant for developing nanoscale\nlight-emitting devices with high efficiency and inter-coupled through nanofiber\nnetworks, highly sensitive optical sensors, and novel laser architectures."
    },
    {
        "anchor": "Growth of alpha-beta phase W thin films over steep Al topography in a\n  confocal sputtering machine: We report on thin-film processing improvements in the fabrication of\nsuperconducting quasiparticle-trap-assisted electrothermal-feedback\ntransition-edge sensors (QETs) used in the design of Cryogenic Dark Matter\nSearch (CDMS) detectors. The work was performed as part of a detector upgrade\nproject that included optimization of a new confocal sputtering system and\ndevelopment of etch recipes compatible with patterning 40 nm-thick, mixed-phase\nW films deposited on 300-600 nm-thick, patterned Al. We found that our standard\nexothermic Al wet etch recipes provided inadequate W/Al interfaces and led to\npoor device performance. We developed a modified Al wet-etch recipe that\neffectively mitigates geometrical step-coverage limitations while maintaining\nour existing device design. Data presented here include SEM and FIB images of\nfilms and device interfaces obtained with the new Al etch method. We also\nintroduce a method for quantitatively measuring the energy collection\nefficiency through these interfaces.",
        "positive": "Observation of the symmetry of core states of a single Fe impurity in\n  GaAs: We report the direct observation of two mid-gap core d-states of differing\nsymmetry for a single Fe atom embedded in GaAs. These states are distinguished\nby the strength of their hybridization with the surrounding host electronic\nstructure. The mid-gap state of Fe that does not hybridize via sigma-bonding is\nstrongly localized to the Fe atom, whereas the other, which does, is extended\nand comparable in size to other acceptor states. Tight-binding calculations of\nthese mid-gap states agree with the spatial structure of the measured wave\nfunctions, and illustrate that such measurements can determine the degree of\nhybridization via pi-bonding of impurity d-states. These single-dopant mid-gap\nstates with strong d-character, which are intrinsically spin-orbit-entangled,\nprovide an opportunity for probing and manipulating local magnetism and may be\nof use for high-speed electrical control of single spins."
    },
    {
        "anchor": "Thermodynamics of mono and di-vacancies in barium titanate: The thermodynamic and kinetic properties of mono and di-vacancy defects in\ncubic (para-electric) barium titanate are studied by means of\ndensity-functional theory calculations. It is determined which vacancy types\nprevail for given thermodynamic boundary conditions. The calculations confirm\nthe established picture that vacancies occur in their nominal charge states\nalmost over the entire band gap. For the dominating range of the band gap the\ndi-vacancy binding energies are constant and negative. The system, therefore,\nstrives to achieve a state in which under metal-rich (oxygen-rich) conditions\nall metal (oxygen) vacancies are bound in di-vacancy clusters. The migration\nbarriers are calculated for mono-vacancies in different charge states. Since\noxygen vacancies are found to readily migrate at typical growth temperatures,\ndi-vacancies can be formed at ease. The key results of the present study with\nrespect to the thermodynamic behavior of mono and di-vacancies influence the\ninitial defect distribution in the ferroelectric phases and therefore the\nconditions for aging.",
        "positive": "Adsorbate Migration Effects on Continuous and Discontinuous\n  Temperature-Dependent Transitions in the Quality Factors of Graphene\n  Nanoresonators: We perform classical molecular dynamics simulation to investigate the\nmechanisms underpinning the unresolved, experimentally-observed\ntemperature-dependent scaling transition in the quality factors of graphene\nnanomechanical resonators (GNMR). Our simulations reveal that the mechanism\nunderlying this temperature scaling phenomenon is the out-of-plane migration of\nadsorbates on GNMRs. Specifically, the migrating adsorbate undergoes frequent\ncollisions with the GNMR, which strongly influences the resulting mechanical\noscillation, and thus the quality factors. We also predict a discontinuous\ntransition in the quality factor at a lower critical temperature, which results\nfrom the in-plane migration of the adsorbate. Overall, our work clearly\ndemonstrates the strong effect of adsorbate migration on the quality factors of\nGNMRs."
    },
    {
        "anchor": "Magnon softening in a ferromagnetic monolayer: a first-principles spin\n  dynamics study: We study the Fe/W(110) monolayer system through a combination of first\nprinciples calculations and atomistic spin dynamics simulations. We focus on\nthe dispersion of the spin waves parallel to the [001] direction. Our results\ncompare favorably with the experimental data of Prokop et al. [Phys. Rev. Lett.\n102, 177206], and correctly capture a drastic softening of the magnon spectrum,\nwith respect to bulk bcc Fe. The suggested shortcoming of the itinerant\nelectron model, in particular that given by density functional theory, is\nrefuted. We also demonstrate that finite temperature effects are significant,\nand that atomistic spin dynamics simulations represent a powerful tool with\nwhich to include these.",
        "positive": "Computational studies for reduced graphene oxide in hydrogen-rich\n  environment: We employ molecular dynamic simulations to study the reduction process of\ngraphene-oxide (GO) in a chemically active environment enriched with hydrogen.\nWe examine the concentration and pressure of hydrogen gas as a function of\ntemperature in which abstraction of oxygen is possible with minimum damage to\nC-sp$^2$ bonds hence preserving the integrity of the graphene sheet. Through\nthese studies we find chemical pathways that demonstrate beneficiary mechanisms\nfor the quality of graphene including formation of water as well as suppression\nof carbonyl pair holes in favor of hydroxyl and epoxy formation facilitated by\nhydrogen gas in the environment."
    },
    {
        "anchor": "Mechanical Properties of Atomically Thin Boron Nitride and the Role of\n  Interlayer Interactions: Atomically thin boron nitride (BN) nanosheets are important two-dimensional\nnanomaterials with many unique properties distinct from those of graphene, but\nthe investigation of their mechanical properties still greatly lacks. Here we\nreport that high-quality single-crystalline mono- and few-layer BN nanosheets\nare one of the strongest electrically insulating materials. More intriguingly,\nfew-layer BN shows mechanical behaviors quite different from those of few-layer\ngraphene under indentation. In striking contrast to graphene, whose strength\ndecreases by more than 30% when the number of layers increases from 1 to 8, the\nmechanical strength of BN nanosheets is not sensitive to increasing thickness.\nWe attribute this difference to the distinct interlayer interactions and hence\nsliding tendencies in these two materials under indentation. The significantly\nbetter mechanical integrity of BN nanosheets makes them a more attractive\ncandidate than graphene for several applications, e.g. as mechanical\nreinforcements.",
        "positive": "Lowering Effective Coordination Promotes Adsorption of NO on Rh(100) and\n  Rh/MgO(100)surfaces: We have studied the adsorption of NO, and the coadsorption of N and O, on\nfour physical and hypothetical systems: unstrained and strained Rh(100)\nsurfaces and monolayers of Rh atoms on strained and unstrained MgO(100)\nsurfaces. We find that as we go from Rh(100) to Rh/Mg0(100), via the other two\nhypothetical systems, the effective coordination progressively decreases, the\n$d$-band narrows and its center shifts closer to the Fermi level, and the\nstrength of adsorption and co-adsorption increases. Both strain and the\npresence of the oxide substrate contribute significantly to this. However,\ncharge-transfer is found to play a negligible role, due to a cancelling out\nbetween donation and back-donation processes. Our results suggest that lowering\neffective coordination of Rh catalysts by strain, roughening or the use of\ninert substrates might improve reaction rates for the reduction of NO to N$_2$."
    },
    {
        "anchor": "Direct calculation of the hard-sphere crystal/melt interfacial free\n  energy: We present a direct calculation by molecular-dynamics computer simulation of\nthe crystal/melt interfacial free energy, $\\gamma$, for a system of hard\nspheres of diameter $\\sigma$. The calculation is performed by thermodynamic\nintegration along a reversible path defined by cleaving, using specially\nconstructed movable hard-sphere walls, separate bulk crystal and fluid systems,\nwhich are then merged to form an interface. We find the interfacial free energy\nto be slightly anisotropic with $\\gamma$ = 0.62$\\pm 0.01$, 0.64$\\pm 0.01$ and\n0.58$\\pm 0.01 k_BT/\\sigma^2$ for the (100), (110) and (111) fcc crystal/fluid\ninterfaces, respectively. These values are consistent with earlier density\nfunctional calculations and recent experiments measuring the crystal nucleation\nrates from colloidal fluids of polystyrene spheres that have been interpreted\n[Marr and Gast, Langmuir {\\bf 10}, 1348 (1994)] to give an estimate of $\\gamma$\nfor the hard-sphere system of $0.55 \\pm 0.02 k_BT/\\sigma^2$, slightly lower\nthan the directly determined value reported here.",
        "positive": "Identification of a Multi-Dimensional Reaction Coordinate for Crystal\n  Nucleation in $\\text{Ni}_3\\text{Al}$: Nucleation during solidification in multi-component alloys is a complex\nprocess that comprises the competition between different crystalline phases as\nwell as chemical composition and ordering. Here, we combine transition\ninterface sampling with an extensive committor analysis to investigate the\natomistic mechanisms during the initial stages of nucleation in\n$\\text{Ni}_3\\text{Al}$. The formation and growth of crystalline clusters from\nthe melt are strongly influenced by the interplay between three descriptors:\nthe size, crystallinity, and chemical short-range order of the emerging nuclei.\nWe demonstrate that it is essential to include all three features in a\nmulti-dimensional reaction coordinate to correctly describe the nucleation\nmechanism, where in particular the chemical short-range order plays a crucial\nrole in the stability of small clusters. The necessity of identifying\nmulti-dimensional reaction coordinates is expected to be of key importance for\nthe atomistic characterization of nucleation processes in complex,\nmulti-component systems."
    },
    {
        "anchor": "High sensitive quasi freestanding epitaxial graphene gassensor on 6H-SiC: We have measured the electrical response to NO$_2$, N$_2$, NH$_3$ and CO for\nepitaxial graphene and quasi freestanding epitaxial graphene on 6H-SiC\nsubstrates. Quasi freestanding epitaxial graphene shows a 6 fold increase in\nNO2 sensitivity compared to epitaxial graphene. Both samples show a sensitivity\nbetter than the experimentally limited 1 ppb. The strong increase in\nsensitivity of quasi freestanding epitaxial graphene can be explained by a\nFermi-energy close to the Dirac Point leading to a strongly surface doping\ndependent sample resistance. Both sensors show a negligible sensitivity to\nN$_2$, NH$_3$ and CO.",
        "positive": "Low Born effective Charges, High Covalency and Strong Optical Activity\n  in $X_3^{2+}$Bi$^{3-}$N$^{3-}$ ($X$=Ca,Sr,Ba) $inverse$-perovskites: We compute for the first time a complete charge analysis (Bader and Born\neffective) on $X_3^{2+}$Bi$^{3-}$N$^{3-}$ ($X$=Ca,Sr,Ba). The crystals show a\ngreat electron sharing with little possibility of ferroelectricity. $Inverse$\nperovskites have been a center of attraction in the recent years and not much\nis known on the systems under this study. This research addressed some key\nmissing components and decomponents like the hardness and optical spectrum in\n$X_3^{2+}$Bi$^{3-}$N$^{3-}$ ($X$=Ca,Sr,Ba). The computed lattices slightly\ndeviated from the parent perovskites indicating a future interfacing under a\nproper substrate. We also found out that all the crystals under this study were\nsemiconducting with direct band gaps but plastic in nature due to strong\ncovalency. The optical spectrum revealed very strong activity in these crystals\nin the ultraviolet regime. The information herein will definitely guide the\nexperimentalist in fabrication of these materials for novel functionalities."
    },
    {
        "anchor": "Why is the bandwidth of sodium observed to be narrower in photoemission\n  experiments?: The experimentally predicted narrowing in the bandwidth of sodium is\ninterpreted in terms of the non-local self-energy effect on quasi-particle\nenergies of the electron liquid. The calculated self-energy correction is a\nmonotonically increasing function of the wavenumber variable. The usual\nanalysis of photo-emission experiments assumes the final state energies on the\nnearly-free-electron-like model and hence it incorrectly ascribes the non-local\nself-energy correction to the final state energies to the occupied state\nenergies, thus leading to a seeming narrowing in the bandwidth.",
        "positive": "Growth of atomically smooth thin films of the electronically phase\n  separated manganite (La$_{0.5}$Pr$_{0.5}$)$_{0.67}$Ca$_{0.33}$MnO$_{3}$: Atomically flat, epitaxial, and stoichiometric thin films of the\nelectronically phase separated compound\n(La$_{0.5}$Pr$_{0.5}$)$_{0.67}$Ca$_{0.33}$MnO$_{3}$ were grown on as-received\nand treated NdGaO$_{3}$ substrates by fine tuning of oxygen pressure during\ndeposition. Optimal thin films with step flow growth mode show superior\nphysical properties compared to thin films grown in off-optimal oxygen\npressures, {\\em viz.} the highest maximum temperature coefficient of\nresistance, the highest peak-resistivity temperature, and reduced coercive\nfields. Transport, magnetization, and x-ray diffraction measurements indicate\nthat the oxygen pressure during growth plays a critical role in the formation\nof oxygen vacancies, cation vacancies, and grain boundaries."
    },
    {
        "anchor": "Asymptotic Expansion Homogenization of Discrete Fine-Scale Models with\n  Rotational Degrees of Freedom for the Simulation of Quasi-Brittle Materials: Discrete fine-scale models, in the form of either particle or lattice models,\nhave been formulated successfully to simulate the behavior of quasi-brittle\nmaterials whose mechanical behavior is inherently connected to fracture\nprocesses occurring in the internal heterogeneous structure. These models tend\nto be intensive from the computational point of view as they adopt an a priori\ndiscretization anchored to the major material heterogeneities (e.g. grains in\nparticulate materials and aggregate pieces in cementitious composites) and this\nhampers their use in the numerical simulations of large systems. In this work,\nthis problem is addressed by formulating a general multiple scale computational\nframework based on classical asymptotic analysis and that (1) is applicable to\nany discrete model with rotational degrees of freedom; and (2) gives rise to an\nequivalent Cosserat continuum. The developed theory is applied to the upscaling\nof the Lattice Discrete Particle Model (LDPM), a recently formulated discrete\nmodel for concrete and other quasi-brittle materials, and the properties of the\nhomogenized model are analyzed thoroughly in both the elastic and inelastic\nregime. The analysis shows that the homogenized micropolar elastic properties\nare size-dependent, and they are functions of the RVE size and the size of the\nmaterial heterogeneity. Furthermore, the analysis of the homogenized inelastic\nbehavior highlights issues associated with the homogenization of fine-scale\nmodels featuring strain-softening and the related damage localization. Finally,\nnonlinear simulations of the RVE behavior subject to curvature components\ncausing bending and torsional effects demonstrates, contrarily to typical\nCosserat formulations, a significant coupling between the homogenized\nstress-strain and couple-curvature constitutive equations.",
        "positive": "Bipolar and unipolar electrical fatigue in ferroelectric lead zirconate\n  titanate thin films: an experimental comparison study: By performing standard PUND (positive-up-negative-down), hysteresis-loop and\ndielectric measurements on the ferroelectric lead zirconate titanate (PZT)\nthin-film capacitors subject to bipolar/unipolar electrical cycling, we show\nthat unipolar fatigue is evident though still less severe than bipolar fatigue\nconducted at the same voltage. That has been attributed to polarization\nretention (backswitching) induced by the residual depolarization field between\nthe monopolar pulses where the applied field is lower than the depolarization\nfield, and explained using the LPD-SICI model (LPD-SICI stands for local phase\ndecomposition caused by switching-induced charge injection). The conventional\nview that switching does not occur during unipolar electrical cycling may need\nto be corrected. PUND results recorded using the pulses of the same voltage as\nthose for repetitive fatigue cycling are not reliable if the voltage is lower\nthan 2Vc (Vc is the saturated coercive voltage). Dielectric measurements or\nhysteresis-loop measurements at higher voltages (e.g. 4Vc) are more reliable\nways to evaluate the degree of fatigue and could provide more valuable\ninformation in such situations. Finally, dielectric results have been used to\nestimate the effective thickness di of the fatigue-induced degraded\n(pyrochlorelike) interfacial layer after bipolar/unipolar fatigue, which has\nnot been done so far to our best knowledge. The fact that di is still much less\nthan the film thickness even after the most severe bipolar fatigue strongly\nsuggests that polarization fatigue in ferroelectrics is an interface effect,\nnot a bulk one."
    },
    {
        "anchor": "Better Band Gaps with Asymptotically Corrected Local Exchange Potentials: We formulate a spin-polarized van Leeuwen and Baerends (vLB) correction to\nthe local density approximation (LDA) exchange potential [Phys. Rev. A 49, 2421\n(1994)] that enforces the ionization potential (IP) theorem following Stein et\nal. [Phys. Rev. Lett. 105, 266802 (2010)]. For electronic-structure problems,\nthe vLB-correction replicates the behavior of exact-exchange potentials, with\nimproved scaling and well-behaved asymptotics, but with the computational cost\nof semi-local functionals. The vLB+IP corrections produces large improvement in\nthe eigenvalues over that from LDA due to correct asympotic behavior and atomic\nshell structures, as shown on rare-gas, alkaline-earth, zinc-based oxides,\nalkali-halides, sulphides, and nitrides. In half-Heusler alloys, this\nasymptotically-corrected LDA reproduces the spin-polarized properties\ncorrectly, including magnetism and half-metallicity. We also considered\nfinite-sized systems [e.g., ringed boron-nitirde (B$_{12}$N$_{12}$) and\ngraphene (C$_{24}$)] to emphasize the wide applicability of the method.",
        "positive": "Extraordinary absorption of sound in porous lamella-crystals: We present the design of a structured material supporting complete absorption\nof sound with a broadband response and functional for any direction of incident\nradiation. The structure which is fabricated out of porous lamellas is arranged\ninto a low-density crystal and backed by a reflecting support. Experimental\nmeasurements show that strong all-angle sound absorption with almost zero\nreflectance takes place for a frequency range exceeding two octaves. We\ndemonstrate that lowering the crystal filling fraction increases the wave\ninteraction time and is responsible for the enhancement of intrinsic material\ndissipation, making the system more absorptive with less material."
    },
    {
        "anchor": "Adsorption of titanium and titanium dioxide on graphene: n and p-type\n  doping: Ab initio calculations within the density-functional theory formalism are\nperformed to investigate the ground state, electric charge doping, and\nelectronic properties of titanium and titanium dioxide monolayers adsorbed on a\ngraphene surface. A new ground state structrure of Ti monolayer adsorbed on\ngraphene is reported which is shown to be stable up to T = 500 K. Effects due\nto lower and higher Ti adatoms coverage are studied. We find that the adsorbed\nTi provides a strong n-type doping which supports recent experimental\nobservations. On the other hand, TiO_2 can induce both p- and n-type doping in\nthe carbon monolayer depending on whether oxygen or titanium atoms are closest\nto the substrate. We identify the structures which are responsible for the\nexperimentally observed autocompensation mechanism that leads to the reversion\nof adsorbate effects after oxidation of the adsorbed Ti.",
        "positive": "Evidence for Emergent Kagome Spin Configuration with Concomitant\n  Transverse and Longitudinal Spin-Glass Freezing in the Chemically Ordered\n  M-type Hexaferrite BaFe12O19: Frustration effects in magnetic systems have traditionally been investigated\nconsidering pre-existing site-disorder or lattice geometry of the\nhigh-temperature paramagnetic phase. We present here evidence for emergence of\ngeometrical frustration as a function of temperature due to spin canting in the\nlong-range ordered (LRO) ferrimagnetic (FMI) phase of BaFe12O19 (BFO), an\nM-type hexaferrite of enormous technological applications. Results of neutron\nscattering and magnetic susceptibility studies on BFO are presented to show for\nthe first time the emergence of highly degenerate kagome spin configuration for\nthe basal plane spin component of BFO with concomitant freezing of transverse\nand longitudinal components of the spins leading to two spin-glass transitions\nin coexistence with the LRO FMI phase. Our results mimic the theoretical\npredictions for concentrated Heisenberg systems even though the source of\nfrustration in BFO is the geometry of the lattice and not site-disorder. We\nbelieve that our findings will stimulate theoretical studies to unravel the\nphysics of spin-glass transitions in LRO systems due to emergent geometrical\nfrustration, an aspect that has remained unexplored so far. We also believe\nthat this work will encourage further experimental studies in search of low\ntemperature spin-glass transition(s) in LRO phases of various hexaferrites and\neven other LRO magnetic compounds with spins arranged on triangular, pyrochlore\nand spinel lattices without any substitutional disorder."
    },
    {
        "anchor": "Amphoteric behavior of Hydrogen in Bimetallic Molecular like Hydrides: Generally hydrogen will adopt the +1, 0 or -1 oxidation state in solids\ndepending upon the chemical environment it occupy. Typically, there are some\nexceptional cases in which hydrogen exhibits both anionic and cationic behavior\nin the same structural frame works. In this study we briefly explore an\namphoteric behavior of hydrogen present in ammine bimetallic borohydrides with\nthe chemical formula M1M2 (BH4)3 (NH3)2 (M1= Na; M2 = Zn, Mg) using the\nstate-of-the-art density functional calculations. In order to establish the\namphoteric behavior of hydrogen in M1M2 (BH4)3 (NH3)2, we have made detailed\nchemical bonding analyses using partial density of states, charge density,\nelectron localization function, and Born effective charge. From these analyses\nwe found that the hydrogen closer to boron is in negative oxidation state\nwhereas the hydrogen closer to nitrogen is in positive oxidation state. The\nestablishment of the present of hydrogen with amphoteric behavior in solids has\nlarge implication on hydrogen storage application.",
        "positive": "Formation and switching of defect dipoles in acceptor doped lead\n  titanate: A kinetic model based on first-principles calculations: The formation and field-induced switching of defect dipoles in acceptor doped\nlead titanate is described by a kinetic model representing an extension of the\nwell established Arlt-Neumann model [Ferroelectrics {\\bf 76}, 303 (1987)].\nEnergy barriers for defect association and reorientation of oxygen\nvacancy-dopant (Cu and Fe) complexes are obtained from first-principles\ncalculations and serve as input data for the kinetic coefficients in the rate\nequation model. The numerical solution of the model describes the time\nevolution of the oxygen vacancy distribution at different temperatures and\ndopant concentrations in the presence or absence of an alternating external\nfield. We predict the characteristic time scale for the alignment of all defect\ndipoles with the spontanenous polarization of the surrounding matrix. In this\nstate the defect dipoles act as obstacles for domain wall motion and contribute\nto the experimentally observed aging. Under cycling conditions the fully\naligned configuration is perturbed and a dynamic equilibrium is established\nwith defect dipoles in parallel and anti-parallel orientation relative to the\nspontaneous polarization. This process can be related to the deaging behavior\nof piezoelectric ceramics."
    },
    {
        "anchor": "Exciton dynamics in different aromatic hydrocarbon systems: The exciton dispersion is examined in the case of four selected prototypical\nmolecular solids: pentacene,tetracene,picene,chrysene. The model parameters are\ndetermined by fitting to experimental data obtained by inelastic electron\nscattering. Within the picture that relies on Frenkel-type excitons we obtain\nthat theoretical dispersion curves along different directions in the Brillouin\nzone are in good agreement with the experimental data, suggesting that the\ninfluence of charge-transfer excitons on exciton dispersion of the analyzed\norganic solids is not as large as proposed. In reciprocal space directions\nwhere Davydov splitting is observed we employ the upgraded version of\nHamiltonian used in Materials 11, 2219 (2018).",
        "positive": "Are Fluorination and Chlorination of the Morpholinium-Based Ionic\n  Liquids Favorable?: Room-temperature ionic liquids (RTILs) constitute a fine-tunable class of\ncompounds. Morpholinium-based cations are new to the field. They are promising\ncandidates for electrochemistry, micellization and catalytic applications. We\ninvestigate halogenation (fluorination and chlorination) of the\nN-ethyl-N-methylmorpholinium cation from thermodynamics perspective. We find\nthat substitutional fluorination is much more energetically favorable than\nsubstitutional chlorination, although the latter is also a permitted process.\nAlthough all halogenation at different locations are possible, they are not\nequally favorable. Furthermore, the trends are not identical in the case of\nfluorination and chlorination. We link the thermodynamic observables to\nelectron density distribution within the investigated cation. The reported\ninsights are based on the coupled-cluster technique, which is a highly accurate\nand reliable electron-correlation method. Novel derivatives of the\nmorpholinium-based RTILs are discussed, motivating further efforts in synthetic\nchemistry."
    },
    {
        "anchor": "Compositional Dependence of Formation Energies of Substitutional and\n  Interstitial Mn in Partially Compensated (Ga,Mn)As: We use the density-functional theory to calculate the total energy of mixed\ncrystals (Ga,Mn)As with a small concentration of various donors. We find that\nthe formation energy of Mn depends strongly on the partial concentrations of Mn\nin the substitutional and interstitial positions, and on the concentration of\nother dopants. The composition dependence of the formation energies represents\nan effective feedback mechanism, resulting in the self-compensation property of\n(Ga,Mn)As. We show that the partial concentrations of both substitutional and\ninterstitial Mn increase proportionally to the total concentration of Mn.",
        "positive": "Coupling Between Magnetic and Transport Properties in Magnetic Layered\n  Material Mn2-xZnxSb: We synthesized single crystals for Mn2-xZnxSb and studied their magnetic and\nelectronic transport properties. This material system displays rich magnetic\nphase tunable with temperature and Zn composition. In addition, two groups of\ndistinct magnetic and electronic properties, separated by a critical Zn\ncomposition of x = 0.6, are discovered. The Zn-less samples are metallic and\ncharacterized by a resistivity jump at the magnetic ordering temperature, while\nthe Zn-rich samples lose metallicity and show a metal-to-insulator\ntransition-like feature tunable by magnetic field. Our findings establish\nMn2-xZnxSb as a promising material platform that offers opportunities to study\nhow the coupling of spin, charge, and lattice degrees of freedom governs\ninteresting transport properties in 2D magnets, which is currently a topic of\nbroad interest."
    },
    {
        "anchor": "Magnetic Stability, Fermi Surface Topology, and Spin-Correlated\n  Dielectric Response in Monolayer 1T-CrTe2: We have carried out density-functional theory (DFT) calculations to study the\nmagnetic stability of both ferromagnetic (FM) and anti-ferromagnetic (AFM)\nstates in monolayer 1T-CrTe2. Our results show that the AFM order is lower in\nenergy and thus is the ground state. By tuning the lattice parameters, the AFM\norder can transition to the FM order, in good agreement with experimental\nobservation. We observe a commensurate SDW alongside the previously predicted\nCDW, and attribute the AFM order to the SDW. This results in distinct hole and\nelectron Fermi pockets and a pronounced optical anisotropy, suggesting\nquasi-one-dimensional behavior in this material.",
        "positive": "Kittel law and domain formation mechanism in PbTiO$_3$/SrTiO$_3$\n  superlattices: We report second-principles simulations on the structural and energetic\nproperties of domains in (PbTiO$_{3}$)$_{n}$/(SrTiO$_{3}$)$_{n}$ superlattices.\nFor the explored layer thickness ($n$ ranging between 8 and 16 unit cells) and\nlateral sizes of the domains, the most stable configuration corresponds to\npolar domains separated by a sequence of counter-rotating vortices\n(clockwise/counterclockwise) perpendicular to the stacking direction and acting\nas domain walls. The balance between the domain wall energy and the\nelectrostatic energy yields to an optimal domain period $\\omega$ that is\nproportional to the square-root of the thickness of the PbTiO$_{3}$ layer,\nfollowing the Kittel law. For a given lateral size of the simulation box,\nsuboptimal domain structures (with a width larger than the one predicted by the\nKittel law) can be obtained in a metastable form. However, at finite\ntemperature, molecular dynamics simulations show the spontaneous change of\nperiodicity, which implies the formation of new domains whose generation is\ninitiated by the nucleation of vortices and antivortices at the interface\nbetween the SrTiO$_{3}$ and the PbTiO$_{3}$ layers. The vortices progressively\nelongate and eventually annihilate with the antivortices yielding the formation\nof new domains to comply the Kittel law via a topological phase transition."
    },
    {
        "anchor": "Exchange Anisotropy in Epitaxial and Polycrystalline NiO/NiFe Bilayers: (001) oriented NiO/NiFe bilayers were grown on single crystal MgO (001)\nsubstrates by ion beam sputtering in order to determine the effect that the\ncrystalline orientation of the NiO antiferromagnetic layer has on the\nmagnetization curve of the NiFe ferromagnetic layer. Simple models predict no\nexchange anisotropy for the (001)-oriented surface, which in its bulk\ntermination is magnetically compensated. Nonetheless exchange anisotropy is\npresent in the epitaxial films, although it is approximately half as large as\nin polycrystalline films that were grown simultaneously. Experiments show that\ndifferences in exchange field and coercivity between polycrystalline and\nepitaxial NiFe/NiO bilayers couples arise due to variations in induced surface\nanisotropy and not from differences in the degree of compensation of the\nterminating NiO plane. Implications of these observations for models of induced\nexchange anisotropy in NiO/NiFe bilayer couples will be discussed.",
        "positive": "Ferron Type of Coductivity in Metal CuFeSe2: It is pointed out, that the charge transfer in the compound in paramagnetic\nregion has a ferron type of transport with ferrons of a small radius, predicted\nby N. Mott. For some another specimen the charge transfer may be carried out by\nferrons of a large radius at very low temperatures. The results are well\nconfirmed by the temperature dependence of resistivity and by metal type of the\ncompound."
    },
    {
        "anchor": "Pinning/depinning of crack fronts in heterogeneous materials: The fatigue fracture surfaces of a metallic alloy, and the stress corrosion\nfracture surfaces of glass are investigated as a function of crack velocity. It\nis shown that in both cases, there are two fracture regimes, which have a well\ndefined self-affine signature. At high enough length scales, the universal\nroughness index 0.78 is recovered. At smaller length scales, the roughness\nexponent is close to 0.50. The crossover length $\\xi_c$ separating these two\nregimes strongly depends on the material, and exhibits a power-law decrease\nwith the measured crack velocity $\\xi_c \\propto v^{-\\phi}$, with $\\phi \\simeq\n1$. The exponents $\\nu$ and $\\beta$ characterising the dependence of $\\xi_c$\nand $v$ upon the pulling force are shown to be close to $\\nu \\simeq 2$ and\n$\\beta \\simeq 2$.",
        "positive": "Snow Crystals: This monograph reviews our current understanding of the physical dynamics of\nice crystal growth, focusing on the spontaneous formation of complex structures\nfrom water vapor (called snow crystals) as a function of temperature,\nsupersaturation, background gas pressure, and other extrinsic parameters. Snow\ncrystal growth is a remarkably rich and rather poorly understood phenomenon,\nrequiring a synthesis of concepts from materials science, crystal-growth\ntheory, statistical mechanics, diffusion-limited solidification, finite-element\nmodeling, and molecular surface processes. Building upon recent advances in\nprecision measurement techniques, computation modeling methods, and molecular\ndynamics simulations of crystalline surfaces, I believe we are moving rapidly\ntoward the long-sought goal of developing a full physical model of snow crystal\nformation, using ab initio molecular dynamics simulations to create a\nsemi-empirical characterization of the nanoscale surface attachment kinetics,\nand then incorporating that into a full computational model that reproduces the\ngrowth of macroscopic crystalline structures. Section 1 of this monograph deals\nmainly with the material properties of ice Ih in equilibrium, including\nthermodynamics quantities, facet surface structures, terrace step energies, and\ncrystal twinning behaviors."
    },
    {
        "anchor": "Defect induced polarization and dielectic relaxation in\n  Ga$_2$$_-$$_x$Fe$_x$O$_3$: We report results of the dielectric and pyroelectric measurements on solid\nsolutions of Ga$_2$$_-$$_x$Fe$_x$O$_3$ with x = 0.75, 1.0 and 1.25. These\nsystems exhibit dipolar cluster glass behavior in addition to the spin glass\nbehavior making them belong to a class of few systems showing multiglass\nbehavior. Presence of two contributing relaxations in dielectric data are\nobserved possibly due to the flipping and breathing of polar nano-clusters.\nFurther, emergence of polarization in these systems can be understood in terms\nof thermally stimulated depolarization current (TSDC) effect caused by defect\ndipoles possibly associated with charged oxygen vacancies rather than the\nintrinsic ferroelectric behavior.",
        "positive": "The Sensitivity of the Magnetic Properties of the ZnCr2O4 and MgCr2O4\n  Spinels to Non-stoichiometry: We report that small amounts of metal atom non-stoichiometry are possible in\nthe ZnCr2O4 and MgCr2O4 spinels. The non-stoichiometry, though less than 2%,\nsignificantly impacts TN and the nature of the magnetic correlations above TN.\nThe Zn1+xCr2-xO4 spinel is particularly sensitive. While stoichiometric ZnCr2O4\ndisplays antiferromagnetic short range correlations in the susceptibility above\nTN, ferromagnetic correlations are observed in non-stoichiometric, hole doped\nZn1+xCr2-xO4. The Mg1+xCr2-xO4 spinels are less profoundly affected by\nnon-stoichiometry, though significant changes are also observed. We contrast\nthe magnetic properties of Zn1+xCr2-xO4 and Mg1+xCr2-xO4 (x=0, 0.02, 0.04) with\nthose of materials with the equivalent amounts of isovalent non-magnetic Ga3+\nsubstituted on the Cr3+ site to separate the effects of static site disorder\nand hole doping."
    },
    {
        "anchor": "Epitaxial growth of highly strained antimonene on Ag (111): The synthesis of antimonene, which is a promising group-V 2D material for\nboth fundamental studies and technological applications, remains highly\nchallenging. Thus far, it has been synthesized only by exfoliation or growth on\na few substrates. In this study, we show that thin layers of antimonene can be\ngrown on Ag (111) by molecular beam epitaxy. High-resolution scanning tunneling\nmicroscopy combined with theoretical calculations revealed that the\nsubmonolayer Sb deposited on a Ag (111) surface forms a layer of AgSb2 surface\nalloy upon annealing. Further deposition of Sb on the AgSb2 surface alloy\ncauses an epitaxial layer of Sb to form, which is identified as antimonene with\na buckled honeycomb structure. More interestingly, the lattice constant of the\nepitaxial antimonene (5 {\\AA}) is much larger than that of freestanding\nantimonene, indicating a high tensile strain of more than 20%. This kind of\nlarge strain is expected to make the antimonene a highly promising candidate\nfor room-temperature quantum spin Hall material.",
        "positive": "Mechanical Controlled Thermal Switch and Hysteresis with Domain Boundary\n  Engineered Phonon Transport: Heat flow control in phononics has received significant attention recently\ndue to its widespread applications in energy transfer, conversion and\nutilization. Here, we demonstrate that by applying external stress or strain we\ncan effectively tune the thermal conductivity through changing the density of\ntwin boundaries, which in turn offers the intriguing mechanical-controlled\nthermal switch and hysteresis operations. Twin boundaries perpendicular to the\ntransport direction strongly scatter phonons. As such, the heat flow is in\ninverse proportional to the density of twin boundaries and hence allows an\nexcellent way to switch thermal conductivity mechanically and even leads to the\ninteresting hysteresis behavior as a thermal memory. Our study provides a novel\nmechanism to couple thermal and mechanical properties of materials as a matter\nof \"domain boundary engineering\" and can have substantial implications in\nflexible thermal control and thermal energy harvesting."
    },
    {
        "anchor": "Out-of-equilibrium Polymorph Selection in Nanoparticle Freezing: The ability to design synthesis processes that are out of equilibrium has\nopened the possibility of creating nanomaterials with remarkable\nphysico-chemical properties, choosing from a much richer palette of possible\natomic architectures compared to equilibrium processes in extended systems. In\nthis work, we employ atomistic simulations to demonstrate how to control\npolymorph selection via cooling rate during nanoparticle freezing in the case\nof Ni$_3$Al, a material with a rich structural landscape. State-of-the-art\nfree-energy calculations allow to rationalize the complex nucleation process,\ndiscovering a switch between two kinetic pathways, yielding the equilibrium\nstructure at room temperature and an alternative metastable one at higher\ntemperature. Our findings address the key challenge in the synthesis of\nnano-alloys for technological applications, i.e., rationally exploiting the\ncompetition between kinetics and thermodynamics by designing a treatment\nhistory that forces the system into desirable metastable states.",
        "positive": "Reducing Disorder in Artificial Kagome Ice: Artificial spin ice has become a valuable tool for understanding magnetic\ninteractions on a microscopic level. The strength in the approach lies in the\nability of a synthetic array of nanoscale magnets to mimic crystalline\nmaterials, composed of atomic magnetic moments. Unfortunately, these nanoscale\nmagnets, patterned from metal alloys, can show substantial variation in\nrelevant quantities such as coercive field, with deviations up to 6%. By\ncarefully studying the reversal process of artificial kagome ice, we can\ndirectly measure the distribution of coercivities, and by switching from\ndisconnected islands to a connected structure, we find that the coercivity\ndistribution can achieve a deviation of only 3.3%. These narrow deviations\nshould allow the observation of behavior that mimics canonical spin-ice\nmaterials more closely."
    },
    {
        "anchor": "Chemical requirements for stabilizing type-II Weyl points in\n  MnBi2-xSbxTe4: We show that type-II Weyl point formation in MnBi2-xSbxTe4 is more likely\nthan in MnBi2Te4 when x reaches 0.5, as the alloy case does not suffer from the\nsame degree of lattice parameter sensitivity as in MnBi2Te4. To further\nsubstantiate the stability of type-II Weyl points in MnBi2-xSbxTe4, we\ndemonstrate that among the three conditions of establishing a type-II Weyl\npoint, two are robustly satisfied by the zone-folded dispersion of Bi and Te pz\norbitals and spin-orbit coupling already available in MnBi2Te4, and that the\ncontrol over MnBi2-xSbxTe4 alloy composition provides a rational means to\nsatisfy the third condition. The stability of type-II Weyl points in\nMnBi1.5Sb0.5Te4 is thus intimately associated with orbital interactions,\nproviding a concrete foundation for future efforts in band engineering and the\nrational design of topological electronic structures.",
        "positive": "An ab initio investigation of Bi$_2$Se$_3$ topological insulator\n  deposited on amorphous SiO$_2$: We use first-principles simulations to investigate the topological properties\nof Bi$_2$Se$_3$ thin films deposited on amorphous SiO2, Bi$_2$Se$_3$/a-SiO$_2$,\nwhich is a promising substrate for topological insulator (TI) based device\napplications. The Bi$_2$Se$_3$ films are bonded to a-SiO$_2$ mediated by van\nder Waals interactions. Upon interaction with the substrate, the Bi$_2$Se$_3$\ntopological surface and interface states remain present, however the degeneracy\nbetween the Dirac-like cones is broken. The energy separation between the two\nDirac-like cones increases with the number of Bi$_2$Se$_3$ quintuple layers\n(QLs) deposited on the substrate. Such a degeneracy breaking is caused by (i)\ncharge transfer from the TI to the substrate and charge redistribution along\nthe Bi$_2$Se$_3$ QLs, and (ii) by deformation of the QL in contact with the\na-SiO$_2$ substrate. We also investigate the role played by oxygen vacancies\n(V$_O$) on the a-SiO$_2$, which increases the energy splitting between the two\nDirac-like cones. Finally, by mapping the electronic structure of\nBi$_2$Se$_3$/a-SiO$_2$, we found that the a-SiO$_2$ surface states, even upon\nthe presence of V$_O$, play a minor role on gating the electronic transport\nproperties of Bi$_2$Se$_3$."
    },
    {
        "anchor": "Decomposition and terapascal phases of water ice: Computational searches for stable and metastable structures of water ice and\nother H:O compositions at TPa pressures have led us to predict that H$_2$O\ndecomposes into H$_2$O$_2$ and a hydrogen-rich phase at pressures of a little\nover 5 TPa. The hydrogen-rich phase is stable over a wide range of hydrogen\ncontents, and it might play a role in the erosion of the icy component of the\ncores of gas giants as H$_2$O comes into contact with hydrogen. Metallization\nof H$_2$O is predicted at a higher pressure of just over 6 TPa, and therefore\nH$_2$O does not have a thermodynamically stable low-temperature metallic form.\nWe have also found a new and rich mineralogy of complicated water ice phases\nwhich are more stable in the pressure range 0.8--2 TPa than any predicted\npreviously.",
        "positive": "Intrinsic Oxygen Vacancy and Extrinsic Aluminium Dopant Interplay: A\n  Route to the Restoration of Defective TiO$_2$: Density functional theory (DFT) and DFT corrected for on-site Coulomb\ninteractions (DFT+U) calculations are presented on Aluminium doping in bulk\nTiO$_2$ and the anatase (101) surface. Particular attention is paid to the\nmobility of oxygen vacancies throughout the doped TiO$_2$ lattice, as a means\nby which charge compensation of trivalent dopants can occur. The effect that Al\ndoping of TiO$_2$ electrodes has in dye sensitised solar cells is explained as\na result of this mobility and charge compensation. Substitutional defects in\nwhich one Al3+ replaces one Ti4+ are found to introduce valence band holes,\nwhile intrinsic oxygen vacancies are found to introduce states in the band-gap.\nCoupling two of these substitutional defects with an oxygen vacancy results in\nexothermic defect formation which maintain charge neutrality. Nudged elastic\nband calculations have been performed to investigate the formation of these\nclustered defects in the (101) surface by oxygen vacancy diffusion, with the\nresulting potential energy surface suggesting energetic gains with small\ndiffusion barriers. Efficiency in- creases observed in dye sensitised solar\ncells as a result of aluminium doping of TiO$_2$ electrodes are investigated by\nadsorbing the tetrahydroquinoline C2-1 chromophore on the defective surfaces.\nAdsorption on the clustered extrinsic Al3+ and intrinsic oxygen vacancy defects\nare found to behave as if adsorbed on a clean surface, with vacancy states not\npresent, while adsorption on the oxygen vacancy results in a down shift of the\ndye localised states within the band-gap and defect states being present below\nthe conduction band edge. Aluminium doping therefore acts as a benign dopant\nfor 'cleaning' TiO$_2$ through oxygen vacancy diffusion."
    },
    {
        "anchor": "High-throughput screening for boride superconductors: A high-throughput screening using density functional calculations is\nperformed to search for stable boride superconductors from the existing\nmaterials database. The workflow employs the fast frozen phonon method as the\ndescriptor to evaluate the superconducting properties quickly. 23 stable\ncandidates are identified from the screening. For almost all found binary\ncompounds, the superconductivity was obtained earlier experimentally or\ncomputationally. For ternary borides, previous studies are very limited. Our\nextensive search among ternary systems confirmed superconductivity in known\nsystems and found several new compounds. Among these discovered superconducting\nternary borides, Ta(MoB)$_2$ shows the highest superconducting temperature of\n~12K. Most predicted compounds were synthesized previously; therefore, our\npredictions can be examined experimentally. Our work also demonstrates that the\nboride systems can have diverse structural motifs that lead to\nsuperconductivity.",
        "positive": "Mesoscale Description of Interface-Mediated Plasticity: Dislocation-interface interactions dictate the mechanical properties of\npolycrystalline materials through dislocation absorption, emission and\nreflection and interface sliding. We derive a mesoscale interface boundary\ncondition to describe these, based on bicrystallography and Burgers vector\nreaction/conservation. The proposed interface boundary condition is built upon\nBurgers vector reaction kinetics and is applicable to any type of interfaces in\ncrystalline materials with any number of slip systems. This approach is applied\nto predict slip transfer for any crystalline interface and stress state;\ncomparisons are made to widely-applied empirical methods. The results are\ndirectly applicable to many existing dislocation plasticity simulation methods."
    },
    {
        "anchor": "Direct evidence of soft mode behavior near the Burns' temperature in\n  PbMg$_{1 / 3}$Nb$_{2 / 3}$O$_{3}$ (PMN) relaxor ferroectric: Inelastic neutron scattering measurements of the relaxor ferroelectric\nPbMg$_{1 / 3}$Nb$_{2 / 3}$O$_{3}$ (PMN) in the temperature range\n490~K$<$T$<$880~K directly observe the soft mode (SM) associated with the\nCurie-Weiss behavior of the dielectric constant $\\varepsilon $(T). The results\nare treated within the framework of the coupled SM and transverse optic (TO1)\nmode and the temperature dependence of the SM frequency at q=0.075 a* is\ndetermined. The parameters of the SM are consistent with the earlier estimates\nand the frequency exhibits a minimum near the Burns temperature ($\\approx $\n650K)",
        "positive": "Strain-driven switching between antiferromagnetic states in frustrated\n  antiferromagnet UO2 probed by exchange bias effect: Frustrated antiferromagnets offer a captivating platform to study the\nintricate relationship of magnetic interactions, geometric constraints, and\nemergent phenomena. By controlling spin orientations, these materials can be\ntailored for applications in spintronics and quantum information processing.\nThe research focuses on the interplay of magnetic and exchange anisotropy\neffects in artificial heterostructures based on a canonical frustrated\nantiferromagnet, UO2. The potential to manipulate the spin directions in this\nmaterial and switch between distinct antiferromagnetic states is investigated\nusing substrate-induced strain. The phenomenon is probed using exchange bias\n(EB) effects in stoichiometric UO2/Fe3O4 bilayers. By employing many-body\nfirst-principles calculations magnetic configurations in the UO2 layers are\nidentified. Even a minor tetragonal distortion triggers a transition between\nantiferromagnetic states of different symmetries, driven by a robust alteration\nof single-ion anisotropy due to the distortion. Consequently, this change\ninfluences the arrangement of magnetic moments at the UO2/Fe3O4 interface,\naffecting the magnitude of exchange bias. The findings showcase how epitaxial\nstrain can effectively manipulate the antiferromagnetic states in frustrated\nantiferromagnets by controlling single-site anisotropy."
    },
    {
        "anchor": "Formation of a highly ordered red phase in a MEH-PPV: polystyrene\n  pseudogels: In this work, we demonstrate the formation of a \"red-phase\" poly[2-methoxy,\n5-(2'- ethyl-hexoxy)-1,4-phenylene vinylene-PPV] (MEH-PPV) embedded into a host\nmatrix of highly entangled ultra-high molecular weight polystyrene\n(MEH-PPV/UHMW PS pseudogel) that allows the simple processing of the MEH-PPV\nsolutions. We processed a \"red-phase\" in the gel, the gel shows that the\nfeatures what have beed demonstrated in the solution can be observed in the\nprocessable gel for optoelectronics applications. [Yamagata, Hajime, and\nHestand, Nicholas J. and Spano, Frank C. and K\u007fohler, Anna and Scharsich,\nChristina and Hoffmann, Sebastian T. and B\u007fassler, Heinz, The Journal of\nChemical Physics, 2013, 139, 114903]",
        "positive": "Comment on \"Hysteretic transition between states of a filled hexagonal\n  magnetic dipole cluster\": In the paper \"Andrew D.P. Smith, Peter T. Haugen, Boyd F. Edwards: Hysteretic\ntransition between states of a filled hexagonal magnetic dipole cluster,\nJournal of Magnetism and Magnetic Materials 549 (2022): 168991\" a hysteretic\ntransition between two stable arrangements of a cluster of seven dipoles is\npresented. The relative strength of the center dipole in a hexagonal\narrangement serves as the bifurcation parameter. The authors clearly\ndemonstrate the existence of two instabilities accompanied by discontinuous\njumps of the dipole arrangement, but leave the question about the nature of\nthese instabilities unanswered. This comment clarifies the nature of the two\ninstabilities: the first one is a symmetry-breaking sub-critical bifurcation\nwith parabolic scaling of the magnetic potential energy difference between the\ntwo branches, and the second one is a fold with its characteristic scaling in\nthe form of a semi-cubic parabola."
    },
    {
        "anchor": "Spin polarization ratios of resistivity and density of states estimated\n  from anisotropic magnetoresistance ratio for nearly half-metallic\n  ferromagnets: We derive a simple relational expression between the spin polarization ratio\nof resistivity, $P_\\rho$, and the anisotropic magnetoresistance ratio $\\Delta\n\\rho/\\rho$, and that between the spin polarization ratio of the density of\nstates at the Fermi energy, $P_{\\rm DOS}$, and $\\Delta \\rho/\\rho$ for nearly\nhalf-metallic ferromagnets. We find that $P_\\rho$ and $P_{\\rm DOS}$ increase\nwith increasing $|\\Delta \\rho/\\rho|$ from 0 to a maximum value. In addition, we\nroughly estimate $P_\\rho$ and $P_{\\rm DOS}$ for a Co$_2$FeGa$_{0.5}$Ge$_{0.5}$\nHeusler alloy by substituting its experimentally observed $\\Delta \\rho/\\rho$\ninto the respective expressions.",
        "positive": "Longitudinal Field Influence on the Phase Transition and Physical\n  Properties of the Kh2po4 Family Ferroelectrics: We verify whether the previously developed model of a KD2PO4 crystal, with\nthe shear strain eps6 taken into account, is able to describe the longitudinal\nelectric field E3 influence on the KH2PO4 family ferroelectrics. Major effects\nof the strain eps6 are splitting of the Slater energies of the short-range\ncorrelations and the effective field created by piezoelectric coupling.\nCalculated TC-E3 phase diagrams, field dependences of polarization,\nsusceptibility, and elastic constant of deuterated KD2PO4 and pure KH2PO4 well\naccord with the available experimental data. For a consistent description of\nall dielectric and piezoelectric characteristics of the crystals, phonon\ndegrees of freedom must be taken into account."
    },
    {
        "anchor": "Magnetic Circular Dichroism Measurements of Thin Films: The difference in the transmission for left and right circularly polarised\nlight though thin films on substrates in a magnetic field is used to obtain the\nmagnetic circular dichroism of the film. However there are reflections at all\nthe interfaces and these are also different for the two polarisations and\ngenerate the polar Kerr signal. In this paper the contribution to the\ndifferences to the total transmission from the transmission across interfaces\nas well as the differences in absorption in the film and the substrate are\ncalculated. This gives a guide to when it is necessary to evaluate these\ncorrections in order to obtain the real MCD from a measure of the differential\ntransmission due to differential absorption in the film.",
        "positive": "Comparative study of H accumulation in differently oriented grains of Cu: When metal surfaces are exposed to hydrogen ion irradiation, the light ions\nare expected to penetrate deep into the material and dissolve in the matrix.\nHowever, these atoms are seen to cause significant modification of surfaces,\nindicating that they accumulate in vicinity of the surface. The process known\nas blistering may reduces the vacuum dielectric strength above the metal\nsurface, which shows a dense population of surface blisters. In this paper, we\ninvestigate how a bubble can grow under the pressure exerted by hydrogen atoms\non the walls of the bubble and how this affect to the surface of Cu, whether an\nexternal electric field is applied or not."
    },
    {
        "anchor": "The Landau-Lifshitz equation in atomistic models: The Landau-Lifshitz (LL) equation, originally proposed at the macrospin\nlevel, is increasingly used in Atomistic Spin Dynamic (ASD) models. The models\nare based on a spin Hamiltonian featuring atomic spins of fixed length, with\nthe exchange introduced using the Heisenberg formalism. ASD models are proving\na powerful approach to the fundamental understanding of ultrafast magnetisation\ndynamics, including the prediction of the thermally induced magnetisation\nswitching phenomenon in which the magnetisation is reversed using an ultrafast\nlaser pulse in the absence of an externally applied field. The paper outlines\nthe ASD model approach and considers the role and limitations of the LL\nequation in this context.",
        "positive": "The density of states of graphene underneath a metal electrode and its\n  correlation with the contact resistivity: The density of states (DOS) of graphene underneath a metal is estimated\nthrough a quantum capacitance measurement of the metal/graphene/SiO2/n+-Si\ncontact structure fabricated by a resist-free metal deposition process.\nGraphene underneath Au maintains a linear DOS - energy relationship except near\nthe Dirac point, whereas the DOS of graphene underneath Ni is broken and\nlargely enhanced around the Dirac point, resulting in only a slight modulation\nof the Fermi energy. Moreover, the DOS of graphene in the contact structure is\ncorrelated with the contact resistivity measured using devices fabricated by\nthe resist-free process."
    },
    {
        "anchor": "Density fitting in periodic systems: application to TDHF in diamond and\n  oxides: A robust density fitting method for calculating Coulomb matrix elements over\nBloch functions based on calculation of two- and three-center matrix elements\nof the Ewald potential is described and implemented in a Gaussian orbital basis\nin the Exciton code. The method is tested by comparing Coulomb and exchange\nenergies from density fitting to corresponding energies from SCF HF\ncalculations for diamond, magnesium oxide and bulk Ne. Density fitting\ncoefficients from the robust method are compared to coefficients from a\nvariational method applied to wave function orbital products in bulk Ne. Four\ncenter Coulomb matrix elements from density fitting are applied to time\ndependent Hartree-Fock (TDHF) calculations in diamond, magnesium oxide and\nanatase and rutile polytypes of titanium dioxide. Shifting virtual states\ndownwards uniformly relative to occupied states and scaling the electron-hole\nattraction term in the TDHF Hamiltonian by 0.4 yields good agreement with\neither experiment and/or Bethe-Salpeter equation calculations. This approach\nmirrors similar 'scissors' adjustments of occupied and virtual states and\nintroduction of a scaled electron-hole attraction term in some time dependent\nDFT calculations.",
        "positive": "Grain boundary stresses in elastic materials: A simple analytical model of intergranular normal stresses is proposed for a\ngeneral elastic polycrystalline material with arbitrary shaped and randomly\noriented grains under uniform loading. The model provides algebraic expressions\nfor the local grain-boundary-normal stress and the corresponding uncertainties,\nas a function of the grain-boundary type, its inclination with respect to the\ndirection of external loading and material-elasticity parameters. The knowledge\nof intergranular normal stresses is a necessary prerequisite in any local\ndamage modeling approach, e.g., to predict the intergranular stress-corrosion\ncracking, grain-boundary sliding or fatigue-crack-initiation sites in\nstructural materials.\n  The model is derived in a perturbative manner, starting with the exact\nsolution of a simple setup and later successively refining it to account for\nhigher order complexities of realistic polycrystalline materials. In the\nsimplest scenario, a bicrystal model is embedded in an isotropic elastic medium\nand solved for uniaxial loading conditions, assuming 1D Reuss and Voigt\napproximations on different length scales. In the final iteration, the grain\nboundary becomes a part of a 3D structure consisting of five 1D chains with\narbitrary number of grains and surrounded by an anisotropic elastic medium.\nConstitutive equations can be solved for arbitrary uniform loading, for any\ngrain-boundary type and choice of elastic polycrystalline material. At each\niteration, the algebraic expressions for the local grain-boundary-normal\nstress, along with the corresponding statistical distributions, are derived and\ntheir accuracy systematically verified and validated against the finite element\nsimulation results of different Voronoi microstructures."
    },
    {
        "anchor": "Data-Driven Modeling of Dislocation Mobility from Atomistics using\n  Physics-Informed Machine Learning: Dislocation mobility, which dictates the response of dislocations to an\napplied stress, is a fundamental property of crystalline materials that governs\nthe evolution of plastic deformation. Traditional approaches for deriving\nmobility laws rely on phenomenological models of the underlying physics, whose\nfree parameters are in turn fitted to a small number of intuition-driven atomic\nscale simulations under varying conditions of temperature and stress. This\ntedious and time-consuming approach becomes particularly cumbersome for\nmaterials with complex dependencies on stress, temperature, and local\nenvironment, such as body-centered cubic crystals (BCC) metals and alloys. In\nthis paper, we present a novel, uncertainty quantification-driven active\nlearning paradigm for learning dislocation mobility laws from automated\nhigh-throughput large-scale molecular dynamics simulations, using Graph Neural\nNetworks (GNN) with a physics-informed architecture. We demonstrate that this\nPhysics-informed Graph Neural Network (PI-GNN) framework captures the\nunderlying physics more accurately compared to existing phenomenological\nmobility laws in BCC metals.",
        "positive": "Exchange bias and training effects in antiferromagnetically coupled\n  La0.7Sr0.3MnO3 / SrRuO3 superlattices: Exchange bias (EB) and the training effects (TE) in an antiferromagnetically\ncoupled La0.7Sr0.3MnO3 / SrRuO3 superlattices were studied in the temperature\nrange 1.8 - 150 K. Strong antiferromagnetic (AFM) interlayer coupling is\nevidenced from AC - susceptibility measurements. Below 100 K, vertical\nmagnetization shifts are present due to the two remanent states corresponding\nto the two ferromagnetic (FM) layers at FM and AFM coupling condition. After\nfield cooling (FC), significant decrease in the exchange bias field (HEB) is\nobserved when cycling the system through several consecutive hysteresis loops.\nQuantitative analysis for the variation of HEB vs. number of field cycles (n)\nindicates an excellent agreement between the theory, based on triggered\nrelaxation phenomena, and our experimental observations. Nevertheless, the\ncrucial fitting parameter K indicates smooth training effect upon repeated\nfield cycling, in accordance with our observation."
    },
    {
        "anchor": "Fifth-degree elastic potential for predictive stress-strain relations\n  and elastic instabilities under large strain and complex loading in Si: Materials under complex loading develop large strains and often transition\nvia an elastic instability, as observed in both simple and complex systems.\nHere, we present Si I under large strain in terms of Lagrangian strain by an\n$5^{th}$-order elastic potential found by minimizing error relative to density\nfunctional theory (DFT) results. The Cauchy stress-Lagrangian strain curves for\narbitrary complex loadings are in excellent correspondence with DFT results,\nincluding elastic instability driving Si I$\\rightarrow$II phase transformation\n(PT) and the shear instabilities. PT conditions for Si I$\\rightarrow$II under\naction of cubic axial stresses are linear in Cauchy stresses in agreement with\nDFT predictions. Such elastic potential permits study of elastic instabilities\nand orientational dependence leading to different PTs, slip, twinning, or\nfracture, providing a fundamental basis for continuum simulations of crystal\nbehavior under extreme loading.",
        "positive": "New symmetric families of silicon quantum dots and their conglomerates\n  as a tunable source of photoluminescence in nanodevices: We propose a new variety of silicon quantum dots containing fullerene-derived\nhollows of nearly arbitrary symmetry. Conglomerate structures are designed by\nconnecting the quantum dots through two kinds of junctions. The quantum\nconfinement effect is investigated using semiempirical quantum-mechanical\nmethod. It is shown that within each family of quantum dots, the band gap and\nthe stability are inversely proportional to the particle effective size.\nQuantum dots inherit a wide variety of structural and symmetry properties from\ntheir parent fullerenes. The conglomerates confine electrons like\nquasi-molecules with a peculiar electronic structure related to the junctions.\nQuantum dots and their conglomerates can host guest atoms in their hollows and\ntherefore present a new promising type of tunable photoluminescent\nnanomaterials."
    },
    {
        "anchor": "Predicting the electronic structure of weakly interacting hybrid\n  systems: The example of nanosized pea-pod structures: We provide a simple scheme for predicting the electronic structure of\nvan-der-Waals bound systems, based on the mere knowledge of the electronic\nstructure of the subunits. We demonstrate this with the example of\nnano-peapods, consisting of polythiophene encapsulated in single-wall carbon\nnanotubes. Using density functional theory we disentangle the contributions to\nthe level alignment. The main contribution is shown to be given by the\nionization potential of the polymer inside the host, which, in turn is\ndetermined by the curvature of the tube. Only a small correction arises from\ncharge redistributions within the domains of the constituents. Polarization\neffects turn out to be minor due to the cylindrical geometry of the peapods and\ntheir dielectric characteristics. Our findings open a perspective towards\ndesigning opto-electronic properties of such complex materials.",
        "positive": "pyCOFBuilder: A python package for automated creation of Covalent\n  Organic Framework models based on the reticular approach: Covalent Organic Frameworks (COFs) have gained significant popularity in\nrecent years due to their unique ability to provide a high surface area and\ncustomizable pore geometry and chemistry. These traits make COFs a highly\npromising choice for a range of applications. However, with their vast\npotential structures, exploring COFs experimentally can be challenging and\ntime-consuming, yet it remains an attractive avenue for computational\nhigh-throughput studies. However, generating COF structures can be a\ntime-consuming and challenging task. To address this challenge, here we\nintroduce the pyCOFBuilder, an open-source Python package designed to\nfacilitate the generation of COF structures for computational studies. The\npyCOFBuilder software provides an easy-to-use set of functionalities to\ngenerate COF structures following the reticular approach. In this paper, we\ndescribe the implementation, main features, and capabilities of the\npyCOFBuilder demonstrating its utility for generating COF structures with\nvarying topologies and chemical properties. pyCOFBuilder is freely available on\nGitHub at https://github.com/lipelopesoliveira/pyCOFBuilder."
    },
    {
        "anchor": "Chirp spectroscopy applied to the characterization of Ferromagnetic\n  Resonance in Magnetic Tunnel Junctions: Magnetic Tunnel Junction devices find use in several applications based on\nthe exploitation of the Spin-Transfer Torque phenomenon. The Ferromagnetic\nResonance curve is a key characteristic of any Magnetic Tunnel Junctions. It is\nusually characterized both experimentally and numerically by performing a lot\nof measurements of the magnetic response to a sinusoidal field or current. Here\nwe propose the use of a chirp signal as excitation signal to reconstruct the\nFerromagnetic resonance curve with a single measurement/simulation. A\nmicromagnetic comparison of the proposed method with the traditional one is\nshown.",
        "positive": "Deriving molecular bonding from macromolecular self-assembly: Macromolecules can form regular structures on inert surfaces. We have\ndeveloped a combined empirical and modeling approach to derive the bonding.\nFrom experimental scanning tunneling microscopy (STM) images of structures\nformed on Au(111) by melamine, by PTCDA, and by a 2:3 mixture of the two, we\ndetermine the molecular bonding morphologies. Within these bonding morphologies\nand recognizing the distinction between cohesive and adhesive molecular\ninteractions we simultaneously simulated different molecular structures using a\nlattice Monte Carlo method. Within these bonding morphologies there is a\ndistinction between cohesive and adhesive molecular interactions. We have\nsimulated different molecular structures using a lattice Monte Carlo method."
    },
    {
        "anchor": "Tunable Giant Rashba-type Spin Splitting in PtSe$_2$/MoSe$_2$\n  Heterostructure: We report a giant Rashba-type spin splitting in two-dimensional\nheterostructure PtSe$_2$/MoSe$_2$ with first-principles calculations. We obtain\na large value of spin splitting energy 110 meV at the momentum offset\n$k_0$=0.23 \\AA$^{-1}$ around $\\mathrm{\\Gamma}$ point, arising from the emerging\nstrong interfacial spin-orbital coupling induced by the hybridization between\nPtSe$_2$ and MoSe$_2$. Moreover, we find that the band dispersion close to\nvalence band maximum around $\\Gamma$ point can be well approximated by the\ngeneralized Rashba Hamiltonian $H(k_{||})=-\\frac{\\hbar^2 k_{||}^2}{2m}+c\nk_{||}+\\alpha_R \\vec{\\sigma}\\cdot(\\vec{k}_{||} \\times \\vec{z})$. It is found\nthat the generalized Rashba constant $\\eta_R=c+\\alpha_R$ in PtSe$_2$/MoSe$_2$\nis as large as 1.3 eV$\\cdot\\text{\\AA}$, and importantly $\\eta_R$ can be\neffectively tuned by biaxial strain and external out-of-plane electrical field,\npresenting a potential application for the spin field-effect transistor. In\naddition, with the spin-valley physics at $\\mathrm{K}/\\mathrm{K}'$ points in\nmonolayer MoSe$_2$, we propose a promising model for spin field-effect\ntransistor with opto-valleytronic spin injection based on PtSe$_2$/MoSe$_2$\nheterostructure.",
        "positive": "Design and Demonstration of Ultra Wide Bandgap AlGaN Tunnel Junctions: Ultra violet light emitting diodes (UV LEDs) face critical limitations in\nboth the injection efficiency and light extraction efficiency due to the\nresistive and absorbing p-type contact layers. In this work, we investigate the\ndesign and application of polarization engineered tunnel junctions for\nultra-wide bandgap AlGaN (Al mole fraction higher than 50%) materials towards\nhighly efficient UV LEDs. We demonstrate that polarization-induced 3D charge is\nbeneficial in reducing tunneling barriers especially for high composition AlGaN\ntunnel junctions. The design of graded tunnel junction structures could lead to\nlow tunneling resistance below 10-3 Ohm cm2 and low voltage consumption below 1\nV (at 1 kA/cm2) for high composition AlGaN tunnel junctions. Experimental\ndemonstration of 292 nm emission was achieved through non-equilibrium hole\ninjection into wide bandgap materials with bandgap energy larger than 4.7 eV,\nand detailed modeling of tunnel junctions shows that they can be engineered to\nhave low resistance, and can enable efficient emitters in the UV-C wavelength\nrange."
    },
    {
        "anchor": "Growth and characterization of n-type electron-induced ferromagnetic\n  semiconductor (In,Fe)As: We show that by introducing isoelectronic iron (Fe) magnetic impurities and\nBeryllium (Be) double-donor atoms into InAs, it is possible to grow a n-type\nferromagnetic semiconductor (FMS) with the ability to control ferromagnetism by\nboth Fe and independent carrier doping by low-temperature molecular-beam\nepitaxy. We demonstrate that (In,Fe)As doped with electrons behaves as an\nn-type electron-induced FMS. This achievement opens the way to realize novel\nspin-devices such as spin light-emitting diodes or spin field-effect\ntransistors, as well as helps understand the mechanism of carrier-mediated\nferromagnetism in FMSs.",
        "positive": "Residual strain in free-standing CdTe nanowires overgrown with HgTe: We investigate the crystal properties of CdTe nanowires overgrown with HgTe.\nScanning electron microscopy (SEM) and scanning transmission electron\nmicroscopy (STEM) confirm, that the growth results in a high ensemble\nuniformity and that the individual heterostructures are single-crystalline,\nrespectively. We use high-resolution X-ray diffraction (HRXRD) to investigate\nstrain, caused by the small lattice mismatch between the two materials. We find\nthat both CdTe and HgTe show changes in lattice constant compared to the\nrespective bulk lattice constants. The measurements reveal a complex strain\npattern with signatures of both uniaxial and shear strains present in the\novergrown nanowires."
    },
    {
        "anchor": "Strain-magneto-optics in CoFe2O4: magneto-absorption in Voight geometry: The infrared optical, magneto-optical and magnetostrictive properties of\nCoFe2O4 single crystal are considered. The magneto-transmission and\nmagneto-reflection of natural light in magnetostrictive CoFe2O4 spinel are\nstudied in the Voight experimental geometry. These magneto-optical effects are\nvery high and associate with a change of the fundamental absorption edge and\nimpurity absorption bands under magnetic field. It is presented the effects\nstrongly depend on both the magnitude and orientation of magnetic field\nrelative to the crystallographic axes of the crystal. The clear connection\nbetween magneto-absorption of light in the infrared spectral range and\nmagnetostriction of CoFe2O4 spinel is established. The contribution of\nmagnetostriction to the magnetic anisotropy constant of the CoFe2O4 crystal is\nshown to be abnormally great.",
        "positive": "Improved Efficiency of Plasmonic Tin Sulfide Solar Cells: Solar cells with the structure ITO-PEDOT:PSS-Ag:SnS-Al were fabricated with\nthe active layer of tin sulphide with silver nano-particles (Ag:SnS) grown by\nthermal co-evaporation. To understand the influence of the silver nanoparticles\non the energy conversion process, various cells with varying active layer\nthicknesses were compared. Results showed that the Ag nanoparticles act as\nscattering centers, resulting in longer optical path lengths for incident\nlight. This in turn results in more charge carriers being generated and thus\nenhances the efficiency of the structure as compared to the pristine\nITO-PEDOT:PSS-SnS-Al structure. The plasmonic solar cells of SnS showed an\nimprovement of more than 40\\%. The results are encouraging and suggests more\nconcerted effort needs to be made on SnS."
    },
    {
        "anchor": "Magnetic Vortex Guide: A concept of magnetic vortex guide is proposed and numerically studied.\nSimilar to the waveguides of electromagnetic waves, a magnetic vortex guide\nallows a vortex domain wall to move along a nanostrip without annihilation at\nthe strip edges. It is shown by micromagnetic simulations that a magnetic\nnanostrip of a properly designed superlattice structure or bilayered structure\ncan serve as vortex guides.",
        "positive": "The microscopic study of a single hydrogen-like impurity in\n  semi-insulating GaAs: The charge dynamics of hydrogen-like centers formed by the implantation of\nenergetic (4 MeV) muons in semi-insulating GaAs have been studied by muon spin\nresonance in electric fields. The results point to the significant role of deep\nhole traps in the compensation mechanism of GaAs. Electric-field-enhanced\nneutralization of deep electron and hole traps by muon-track-induced hot\ncarriers results to an increase of the non-equilibrium carrier life-times. As a\nconsequence, the muonium ($\\mu^+ + e^-$) center at the tetrahedral As site can\ncapture the track's holes and therefore behaves like a donor."
    },
    {
        "anchor": "Learning with Delayed Rewards -- A case study on inverse defect design\n  in 2D materials: Defect dynamics in materials are of central importance to a broad range of\ntechnologies from catalysis to energy storage systems to microelectronics.\nMaterial functionality depends strongly on the nature and organization of\ndefects, their arrangements often involve intermediate or transient states that\npresent a high barrier for transformation. The lack of knowledge of these\nintermediate states and the presence of this energy barrier presents a serious\nchallenge for inverse defect design, especially for gradient-based approaches.\nHere, we present a reinforcement learning (Monte Carlo Tree Search) based on\ndelayed rewards that allow for efficient search of the defect configurational\nspace and allows us to identify optimal defect arrangements in low dimensional\nmaterials. Using a representative case of 2D MoS2, we demonstrate that the use\nof delayed rewards allows us to efficiently sample the defect configurational\nspace and overcome the energy barrier for a wide range of defect concentrations\n(from 1.5% to 8% S vacancies), the system evolves from an initial randomly\ndistributed S vacancies to one with extended S line defects consistent with\nprevious experimental studies. Detailed analysis in the feature space allows us\nto identify the optimal pathways for this defect transformation and\narrangement. Comparison with other global optimization schemes like genetic\nalgorithms suggests that the MCTS with delayed rewards takes fewer evaluations\nand arrives at a better quality of the solution. The implications of the\nvarious sampled defect configurations on the 2H to 1T phase transitions in MoS2\nare discussed. Overall, we introduce a Reinforcement Learning (RL) strategy\nemploying delayed rewards that can accelerate the inverse design of defects in\nmaterials for achieving targeted functionality.",
        "positive": "Determination of the high-pressure crystal structure of BaWO4 and PbWO4: We report the results of both angle-dispersive x-ray diffraction and x-ray\nabsorption near-edge structure studies in BaWO4 and PbWO4 at pressures of up to\n56 GPa and 24 GPa, respectively. BaWO4 is found to undergo a pressure-driven\nphase transition at 7.1 GPa from the tetragonal scheelite structure (which is\nstable under normal conditions) to the monoclinic fergusonite structure whereas\nthe same transition takes place in PbWO4 at 9 GPa. We observe a second\ntransition to another monoclinic structure which we identify as that of the\nisostructural phases BaWO4-II and PbWO4-III (space group P21/n). We have also\nperformed ab initio total energy calculations which support the stability of\nthis structure at high pressures in both compounds. The theoretical\ncalculations further find that upon increase of pressure the scheelite phases\nbecome locally unstable and transform displacively into the fergusonite\nstructure. The fergusonite structure is however metastable and can only occur\nif the transition to the P21/n phases were kinetically inhibited. Our\nexperiments in BaWO4 indicate that it becomes amorphous beyond 47 GPa."
    },
    {
        "anchor": "Contrasting behavior of the structural and magnetic properties in Mn-\n  and Fe-doped In$_2$O$_3$ films: We have observed room temperature ferromagnetism (FM) in In$_2$O$_3$ thin\nfilms doped with either 5 at.% Mn or Fe, prepared by pulsed laser deposition\n(PLD) at substrate temperatures ranging from 300 to 600$\\,^{\\circ}{\\rm C}$. The\ndependence of saturation magnetization on grain size was investigated for both\ntypes of In$_2$O$_3$ films. It is revealed that, for the Mn-doped films, the\nmagnetization was largest with small grains, indicating the importance of grain\nboundaries. In contrast, for Fe-doped films, the largest magnetization was\nobserved with large grains.",
        "positive": "Thermodynamically stable lithium silicides and germanides from\n  density-functional theory calculations: Density-functional-theory (DFT) calculations have been performed on the Li-Si\nand Li-Ge systems. Lithiated Si and Ge, including their metastable phases, play\nan important technological r\\^ole as Li-ion battery (LIB) anodes. The\ncalculations comprise structural optimisations on crystal structures obtained\nby swapping atomic species to Li-Si and Li-Ge from the X-Y structures in the\nInternational Crystal Structure Database, where X={Li,Na,K,Rb,Cs} and\nY={Si,Ge,Sn,Pb}. To complement this at various Li-Si and Li-Ge stoichiometries,\nab initio random structure searching (AIRSS) was also performed. Between the\nground-state stoichiometries, including the recently found Li$_{17}$Si$_{4}$\nphase, the average voltages were calculated, indicating that germanium may be a\nsafer alternative to silicon anodes in LIB, due to its higher lithium insertion\nvoltage. Calculations predict high-density Li$_1$Si$_1$ and Li$_1$Ge$_1$\n$P4/mmm$ layered phases which become the ground state above 2.5 and 5 GPa\nrespectively and reveal silicon and germanium's propensity to form dumbbells in\nthe Li$_x$Si, $x=2.33-3.25$ stoichiometry range. DFT predicts the stability of\nthe Li$_{11}$Ge$_6$ $Cmmm$, Li$_{12}$Ge$_7$ $Pnma$ and Li$_7$Ge$_3$ $P32_12$\nphases and several new Li-Ge compounds, with stoichiometries Li$_5$Ge$_2$,\nLi$_{13}$Ge$_5$, Li$_8$Ge$_3$ and Li$_{13}$Ge$_4$."
    },
    {
        "anchor": "Effective separation of photogenerated electron-hole pairs by radial\n  field facilitates ultrahigh photoresponse in single semiconductor nanowire\n  photodetectors: We report an investigation on the observation of ultrahigh photoresponse\n(photogain, G_Pc>106) in single nanowire photodetectors of diameter < 100 nm.\nThe investigation which is a combination of experimental observations and a\ntheoretical analysis of the ultrahigh optical response of semiconductor\nnanowires, has been carried out with emphasis on Ge nanowires. Semiconductor\nnanowire photodetectors show a signature of photogating where G_Pc rolls-off\nwith increasing illumination intensity. We show that surface band bending due\nto depleted surface layers in nanowires induces a strong radial field (~ 108\nV/m at the nanowire surface) which causes physical separation of photogenerated\nelectron-hole pairs. This was established quantitatively through a\nself-consistent theoretical model based on coupled Schrodinger and Poisson\nEquations. It shows that carrier separation slows down the surface\nrecombination velocity to a low value (< 1 cm/s) thus reducing the carrier\nrecombination rate and extending the recombination lifetime by few orders of\nmagnitude. An important outcome of the model is the prediction of G_Pc ~ 106 in\na single Ge nanowire (with diameter 60 nm), which matches well with our\nexperimental observation. The model also shows an inverse dependence of G_Pc on\nthe diameter that has been observed experimentally. Though carried out in\ncontext of Ge nanowires, the physical model developed has general applicability\nin other semiconductor nanowires as well.",
        "positive": "Low temperature synthesis of BiFeO$_{3}$ nanoparticles with enhanced\n  magnetization and promising photocatalytic performance in dye degradation and\n  hydrogen evolution: In this investigation, we have synthesized BiFeO$_{3}$ nanoparticles by\nvarying hydrothermal reaction temperatures from 200 $^{\\circ}$C to 120\n$^{\\circ}$C to assess their visible-light-driven photocatalytic activity along\nwith their applicability for hydrogen production via water splitting. The\nrhombohedral perovskite structure of BiFeO$_{3}$ is formed for hydrothermal\nreaction temperature up to 160 $^{\\circ}$C, however, for a further decrement of\nreaction temperature a mixed sillenite phase is observed. The XRD Rietveld\nanalysis, XPS analysis and FESEM imaging ensure the formation of single-phase\nand well crystalline nanoparticles at 160 $^{\\circ}$C reaction temperature with\n20 nm of average size. The nanoparticles fabricated at this particular reaction\ntemperature also exhibit improved magnetization, reduced leakage current\ndensity and excellent ferroelectric behavior. These nanoparticles demonstrate\nconsiderably high absorbance in the visible range with a low bandgap (2.1 eV).\nThe experimentally observed bandgap is in excellent agreement with the\ncalculated bandgap using the first-principles calculations. The favorable\nphotocatalytic performance of these nanoparticles has been able to generate\nmore than two times of solar hydrogen compared to that produced by bulk\nBiFeO$_{3}$ as well as commercially available Degussa P25 titania. Notably, the\nexperimentally observed bandgap is almost equal for both bulk material and\nnanoparticles prepared at different reaction temperatures. Therefore, in solar\nenergy applications, the superiority of BFO nanoparticles prepared at 160\n$^{\\circ}$C reaction temperature may be attributed not only to solely their\nbandgap but also to other factors, such as reduced particle size, excellent\nmorphology, well crystallinity, large surface to volume ratio, ferroelectricity\nand so on."
    },
    {
        "anchor": "Ferroelectricity in crystals with non-polar point groups: Ferroelectric crystals must adopt one of the 10 polar point groups according\nto the Neumann's principle. In this paper we propose that this conclusion is\nbased on perfect bulk crystals without taking the boundaries into account, and\nwe show first-principles evidence that ferroelectric polarizations may also be\nformed in some non-polar point groups as the edges generally break the crystal\nsymmetry, which may even maintain at macroscale. They can be switchable in some\nsystems with weak van der Waals bondings or covalent-like ionic bondings where\nlong ion displacements with moderate barriers are possible. Such unconventional\nferroelectricity violates the Neumann's principle and Abrahams' conditions\nrespectively due to the boundaries and long ion displacements, which may\nexplain some unclarified phenomena reported previously as well as significantly\nexpand the scope of ferroelectrics.",
        "positive": "Rapid Reconstruction of 3-D Membrane Pore Structure Using a Single 2-D\n  Micrograph: Conventional 2-D scanning electron microscopy (SEM) is commonly used to\nrapidly and qualitatively evaluate membrane pore structure. Quantitative 2-D\nanalyses of pore sizes can be extracted from SEM, but without information about\n3-D spatial arrangement and connectivity, which are crucial to the\nunderstanding of membrane pore structure. Meanwhile, experimental 3-D\nreconstruction via tomography is complex, expensive, and not easily accessible.\nHere, we employ data-science tools to demonstrate a proof-of-principle\nreconstruction of the 3-D structure of a membrane using a single 2-D image\npulled from a 3-D tomographic data set. The reconstructed and experimental 3-D\nstructures were then directly compared, with important properties such as mean\npore radius, mean throat radius, coordination number and tortuosity differing\nby less than 15%. The developed algorithm will dramatically improve the ability\nof the membrane community to characterize membranes, accelerating the design\nand synthesis of membranes with desired structural and transport properties."
    },
    {
        "anchor": "Beta-NMR of Isolated Lithium in Nearly Ferromagnetic Palladium: The temperature dependence of the frequency shift and spin-lattice relaxation\nrate of isolated, nonmagnetic Li-8 impurities implanted in a nearly\nferromagnetic host (Pd) are measured by means of beta-detected nuclear magnetic\nresonance (b-NMR). The shift is negative, very large and increases\nmonotonically with decreasing T in proportion to the bulk susceptibility of Pd\nfor T > T*~ 100 K. Below T*, an additional shift occurs which we attribute to\nthe response of Pd to the defect. The relaxation rate is much slower than\nexpected for the large shift and is linear with T below T*, showing no sign of\nadditional relaxation mechanisms associated with the defect.",
        "positive": "Correlations, disorder, and multi-magnon processes in terahertz spin\n  dynamics of magnetic nanostructures: A first-principles investigation: Understanding the profound impact of correlation effects and crystal\nimperfections is essential for an accurate description of solids. Here we study\nthe role of correlation, disorder, and multi-magnon processes in THz magnons.\nOur findings reveal that a significant part of the electron self-energy, which\ngoes beyond the adiabatic local spin density approximation, arises from the\ninteraction between electrons and a virtual magnon gas. This interaction leads\nto a substantial modification of the exchange splitting and a renormalization\nof magnon energies, in agreement with the experimental data. We establish a\nquantitative hierarchy of magnon relaxation processes based on first\nprinciples."
    },
    {
        "anchor": "Giant Linear Magneto-resistance in Nonmagnetic PtBi2: We synthesized nonmagnetic PtBi$_2$ single crystals and observed a giant\nlinear magneto-resistance (MR) up to 684\\% under a magnetic field $\\mu_0H$ = 15\nT at $T$ = 2 K. The linear MR decreases with increasing temperature, but it is\nstill as large as 61\\% under $\\mu_0H$ of 15 T at room temperature. Such a giant\nlinear MR is unlikely to be described by the quantum model as the quantum\ncondition is not satisfied. Instead, we found that the slope of MR scales with\nthe Hall mobility, and it can be well explained by a classical disorder model.",
        "positive": "Precision-controlled ultrafast electron microscope platforms. A case\n  study: Multiple-order coherent phonon dynamics in 1T-TaSe$_2$ probed at 50\n  femtosecond - 10 femtometer scales: We report on the first detailed beam test attesting the fundamental principle\nbehind the development of high-current-efficiency ultrafast electron microscope\nsystems where a radio-frequency cavity is incorporated as a condenser lens in\nthe beam delivery system. To allow the experiment to be carried out with a\nsufficient resolution to probe the performance at the emittance floor, a new\ncascade loop RF controller system is developed to reduce the RF noise floor.\nTemporal resolution at 50 femtoseconds in full-width-at-half-maximum and\ndetection sensitivity better than 1% are demonstrated on exfoliated 1T-TaSe$_2$\nlayers where the multi-order edge-mode coherent phonon excitation is employed\nas the standard candle to benchmark the performance. The high temporal\nresolution and the significant visibility to very low dynamical contrast in\ndiffraction signals give strong support to the working principle of the\nhigh-brightness beam delivery via phase-space manipulation in the electron\nmicroscope system."
    },
    {
        "anchor": "Role of Brownian motion and N\u00e9el relaxations in Mossbauer spectra of\n  magnetic liquids: The absorption cross section of M\\\"{o}ssbauer radiation in magnetic liquids\nis calculated, taking into consideration both translational and rotational\nBrownian motion of magnetic nanoparticles. Stochastic reversals of their\nmagnetization are also regarded in the absence of external magnetic field. The\nrole of Brownian motion in ferrofluids is considered in the framework of the\ndiffusion theory, while for the magnetorheological fluids with large\nnanoparticles it is done in the framework of the Langevin's approach. For\nrotation we derived the equation analogous to Langevin's equation and gave the\ncorresponding correlation function. In both cases the equations for rotation\nare solved in the approximation of small rotations during lifetime of the\nexcited state of M\\\"{o}ssbauer nuclei. The influence of magnetization\nrelaxations is studied with the aid of the Blume-Tjon model.",
        "positive": "Beating oscillations of magneto-optical spectra in simple hexagonal\n  graphite: The magneto-optical properties of simple hexagonal graphite exhibit rich\nbeating oscillations, which are dominated by the field strength and photon\nenergy. The former has a strong effect on the intensity, the energy range of\nthe beating and the number of groups, and the latter modulates the total group\nnumbers of the oscillation structures. The single-particle and collective\nexcitations are simultaneously presented in the magnetoreflectance spectra and\ncan be precisely distinguished. For the loss function and reflectance, the\nbeating pattern of the first group displays stronger intensities and broader\nenergy range than other groups. Simple hexagonal graphite possesses unique\nmagneto-optical characteristics that can serve to identify other bulk\ngraphites."
    },
    {
        "anchor": "Internal Rotation of Disilane and Related Molecules:a Density Functional\n  Study: DFT calculations performed on Si_2H_6, Si_2F_6, Si_2Cl_6, and Si_2Br_6 are\nreported. The evolution of the energy, the chemical potential and the molecular\nhardness, as a function of torsion angle, is studied. Results at the\nDFT-B3LYP/6-311++G** level show that the molecules always favor the stable\nstaggered conformations, with low but significant energy barriers that hinder\ninternal rotation. The chemical potential and hardness of Si_2H_6 remains quite\nconstant as the sylil groups rotate around the Si-Si axis, whereas the other\nsystems exhibit different degrees of rearrangement of the electronic density as\na function of the torsion angle. A qualitative analysis of the frontier\norbitals shows that the effect of torsional motion on electrophilic attack is\nnegligible, whereas this internal rotation may generate different specific\nmechanisms for nucleophilic attack.",
        "positive": "Ferromagnetism and Wigner crystallization in Kagome graphene and related\n  structures: Interaction in a flat band is magnified due to the divergence in the density\nof states, which gives rise to a variety of many-body phenomena such as\nferromagnetism and Wigner crystallization. Until now, however, most studies of\nthe flat band physics are based on model systems, making their experimental\nrealization a distant future. Here, we propose a class of systems made of real\natoms, namely, carbon atoms with realistic physical interactions (dubbed here\nas Kagome graphene/graphyne). Density functional theory calculations reveal\nthat these Kagome lattices offer a controllable way to realize robust flat\nbands sufficiently close to the Fermi level. Upon hole doping, they split into\nspin-polarized bands at different energies to result in a flat-band\nferromagnetism. At a half filling, this splitting reaches its highest level of\n768 meV. At smaller fillings, e.g., when {\\nu}=1/6, on the other hand, a Wigner\ncrystal spontaneously forms, where the electrons form closed loops localized on\nthe grid points of a regular triangular lattice. It breaks the translational\nsymmetry of the original Kagome lattice. We further show that the Kagome\nlattices exhibit good mechanical stabilities, based on which a possible route\nfor experimental realization of the Kagome graphene is also proposed."
    },
    {
        "anchor": "Stable Dirac semi-metal in the allotrope of IV elements: Three dimensional topological Dirac semi-metals represent a novel state of\nquantum matter with exotic electronic properties, in which a pair of Dirac\npoints with the linear dispersion along all momentum directions exist in the\nbulk. Herein, by using the first principles calculations, we discover a new\nmetastable allotrope of Ge and Sn in the staggered layered dumbbell structure,\nnamed as germancite and stancite, to be Dirac semi-metals with a pair of Dirac\npoints on its rotation axis. On the surface parallel to the rotation axis, a\npair of topologically non-trivial Fermi arcs are observed and a Lifshitz\ntransition is found by tuning the Fermi level. Furthermore, the quantum thin\nfilm of germancite is found to be an intrinsic quantum spin Hall insulator.\nThese discoveries suggest novel physical properties and future applications of\nthe new metastable allotrope of Ge and Sn.",
        "positive": "Defect-induced magnetism in SiC: Interplay between ferromagnetism and\n  paramagnetism: Defect-induced ferromagnetism has triggered a lot of investigations and\ncontroversies. The major issue is that the induced ferromagnetic signal is so\nweak that it can sufficiently be accounted for by trace contamination. To\nresolve this issue, we studied the variation of the magnetic properties of SiC\nafter neutron irradiation with fluence covering four orders of magnitude. A\nlarge paramagnetic component has been induced and scales up with defect\nconcentration, which can be well accounted for by uncoupled divacancies.\nHowever, the ferromagnetic contribution is still weak and only appears in the\nlow fluence range of neutrons or after annealing treatments. First-principles\ncalculations hint towards a mutually exclusive role of the concentration of\ndefects: Defects favor spin polarization at the expense of magnetic\ninteraction. Combining both experimental and first-principles calculation\nresults, the defect-induced ferromagnetism can be understood as a local effect\nwhich cannot be scaled up with the volume. Therefore, our investigation answers\nthe long-standing question why the defect-induced ferromagnetic signal is weak."
    },
    {
        "anchor": "Large Exciton Binding Energy in the Bulk van der Waals Magnet CrSBr: Excitons, bound electron-hole pairs, influence the optical properties in\nstrongly interacting solid state systems. Excitons and their associated\nmany-body physics are typically most stable and pronounced in monolayer\nmaterials. Bulk systems with large exciton binding energies, on the other hand,\nare rare and the mechanisms driving their stability are still relatively\nunexplored. Here, we report an exceptionally large exciton binding energy in\nsingle crystals of the bulk van der Waals antiferromagnet CrSBr. Utilizing\nstate-of-the-art angle-resolved photoemission spectroscopy and self-consistent\nab-initio GW calculations, we present direct spectroscopic evidence that robust\nelectronic and structural anisotropy can significantly amplify the exciton\nbinding energy within bulk crystals. Furthermore, the application of a vertical\nelectric field enables broad tunability of the optical and electronic\nproperties. Our results indicate that CrSBr is a promising material for the\nstudy of the role of anisotropy in strongly interacting bulk systems and for\nthe development of exciton-based optoelectronics.",
        "positive": "Spin-orbit interaction in the k \\cdot p theory for cubic crystals: Recent work by Elder, Ward and Zhang [Phys. Rev. B83. 165210 (2011)] has\nshown need for correction and modification of current implementation of the k.p\nmethod and operator ordering scheme using the interaction parameters defined\nunder double group consideration. This manuscript examines the difference in\ntreatment of spin-orbit interaction under the single and double group\nformulations. We show that the restriction to the adapted double group bases,\nbrought about by the imposition of single group selection rule in calculating\nthe k.p interaction, is not appropriate. In addition, the unitary\ntransformation employed in the literature to diagonalise the intra-band spin\norbit interaction in semiconductors with diamond lattice can not remove the\ninter-band terms. It leads to a bases set for valence band ordered differently\nfrom D_3/2^+ in the O(3) group thus invalidating any correlation of magnetic\nquantum number to the z component of angular momentum. Under the double group\nconsideration, spin-orbit interaction affects all the zone centre states and\noffers a mechanism for changing the relative positions of various zone centre\nstates in the conduction band. In addition to the mixing caused by k\nindependent spin orbit terms, formation of hybridised orbitals under double\ngroup rules also produce mixing. This can lead to inversion in materials such\nas \\alpha-tin. The re-arrangement of conduction band zone centre states leads\nto a negative \\gamma_2 in most materials with respect to the valence band bases\nhaving the same order as D_3/2^+ in the O(3) group. The double group\nformulation is also required in the description of Zeeman interaction,\nincluding the S.B term, for the mixed zone centre states. It provides a\ncorrespondence between second order interaction parameters and the Luttinger\ninvariants. ..."
    },
    {
        "anchor": "Heteroepitaxial Thin-Film Growth of a Ternary Nitride Semiconductor\n  CaZn2N2: Zinc-based nitride CaZn2N2 films grown by molecular beam epitaxy (MBE) with a\nplasma-assisted active nitrogen-radical source are promising candidates of\nnext-generation semiconductors for light-emitting diodes and solar cells. This\nnitride compound has previously only been synthesized in a bulk form by\nultrahigh-pressure synthesis at 5 GPa. Three key factors have been found to\nenable heteroepitaxial film growth: (i) precise tuning of the individual flux\nrates of Ca and Zn, (ii) the use of GaN template layers on sapphire c-plane as\nsubstrates, and (iii) the application of MBE with an active N-radical source.\nBecause other attempts at physical vapor deposition and thermal annealing\nprocesses have not produced CaZn2N2 films of any phase, this rf-plasma-assisted\nMBE technique represents a promising way to stabilize CaZn2N2 epitaxial films.\nThe estimated optical band gap is ~1.9 eV, which is consistent with the value\nobtained from bulk samples. By unintentional carrier doping, n- and p-type\nelectronic conductions are attained with low carrier densities of the order of\n1013 /cm3. These features represent clear advantages when compared with\nZn-based oxide semiconductors, which usually have much higher carrier densities\nirrespective of their intentionally undoped state. The carrier mobilities at\nroom temperature are 4.3 cm2/(Vs) for electrons and 0.3 cm2/(Vs) for hole\ncarriers, which indicates that transport properties are limited by grain\nboundary scattering, mainly because of the low-temperature growth at 250\n{\\deg}C, which realizes a high nitrogen chemical potential.",
        "positive": "Phase diagram of silica from computer simulation: We evaluate the phase diagram of the ``BKS'' potential [Van Beest, Kramer and\nvan Santen, Phys. Rev. Lett. 64, 1955 (1990)], a model of silica widely used in\nmolecular dynamics (MD) simulations. We conduct MD simulations of the liquid,\nand three crystals (beta-quartz, coesite and stishovite) over wide ranges of\ntemperature and density, and evaluate the total Gibbs free energy of each\nphase. The phase boundaries are determined by the intersection of these free\nenergy surfaces. Not unexpectedly for a classical pair potential, our results\nreveal quantitative discrepancies between the locations of the BKS and real\nsilica phase boundaries. At the same time, we find that the topology of the\nreal phase diagram is reproduced, confirming that the BKS model provides a\nsatisfactory qualitative description of a silica-like material. We also compare\nthe phase boundaries with the locations of liquid-state thermodynamic anomalies\nidentified in previous studies of the BKS model."
    },
    {
        "anchor": "Subterahertz spin pumping from an insulating antiferromagnet: Spin-transfer torque and spin Hall effects combined with their reciprocal\nphenomena, spin-pumping and inverse spin Hall (ISHE) effects, enable the\nreading and control of magnetic moments in spintronics. The direct observation\nof these effects remains elusive in antiferromagnetic-based devices. We report\nsub-terahertz spin-pumping at the interface of a uniaxial insulating\nantiferromagnet MnF2 and platinum. The measured ISHE voltage arising from\nspin-charge conversion in the platinum layer depends on the chirality of the\ndynamical modes of the antiferromagnet, which is selectively excited and\nmodulated by the handedness of the circularly polarized sub-THz irradiation.\nOur results open the door to the controlled generation of coherent pure spin\ncurrents at THz frequencies.",
        "positive": "First-principles study of phonon anharmonicity and negative thermal\n  expansion in ScF3: The microscopic origin of the large negative thermal expansion of cubic\nscandium trifluorides (ScF3) is investigated by performing a set of anharmonic\nfree-energy calculations based on density functional theory. We demonstrate\nthat the conventional quasiharmonic approximation (QHA) completely breaks down\nfor ScF3 and the quartic anharmonicity, treated nonperturbatively by the\nself-consistent phonon theory, is essential to reproduce the observed\ntransition from negative to positive thermal expansivity and the hardening of\nthe R4+ soft mode with heating. In addition, we show that the contribution from\nthe cubic anharmonicity to the vibrational free energy, evaluated by the\nimproved self-consistent phonon theory, is significant and as important as that\nfrom the quartic anharmonicity for robust understandings of the temperature\ndependence of the thermal expansion coefficient. The first-principles approach\nof this study enables us to compute various thermodynamic properties of solids\nin the thermodynamic limit with the effects of cubic and quartic\nanharmonicities. Therefore, it is expected to solve many known issues of the\nQHA-based predictions particularly noticeable at high temperature and in\nstrongly anharmonic materials."
    },
    {
        "anchor": "Self-organized synthesis of patterned magnetic nanostructures with\n  in-plane and perpendicular to the plane magnetization: Patterned arrays of ferromagnetic nanoparticles of Co, Ni, and Fe_{\\text{50}}\nCo_{\\text{50}} have been synthesized from their ultrathin metal films on\nSiO_{\\text{2}} substrate by nanosecond laser-induced self-organization. The\nmorphology, nanostructure, and magnetic behavior of the nanoparticle arrays\nwere investigated by a combination of electron, atomic force, and magnetic\nforce microscopy techniques. Transmission electron microscopy investigations\nrevealed a granular polycrystalline nanostructure, with the number of grains\ninside the nanoparticle increasing with their diameter. Magnetic force\nmeasurements showed that the magnetization direction of the Co and Ni\nnanoparticles was predominantly out-of-plane while those for the\nFe_{\\text{50}}Co_{\\text{50}} alloy was in the plane of the substrate. This\ndifference in behavior is due to the dominating influence of magnetostrictive\nenergy on the magnetization as a result of residual thermal strain following\nfast laser processing. Since the magnetostriction coefficient is negative for\npolycrystalline Co and Ni, and positive for Fe_{\\text{50}}Co_{\\text{50}}, the\ntensile residual strain forces the magnetization direction of the negative\nmagnetostriction materials out-of-plane and the positive magnetostriction\nmaterials in-plane. This demonstrates a cost-effective non-epitaxial technique\nfor the fabrication of patterned arrays of magnetic nanoparticles with tailored\nmagnetization orientations.",
        "positive": "Simplified bond-hyperpolarizability model of second-harmonic-generation\n  in Si(111): theory and experiment: Second-harmonic-generation (SHG) in centrosymmetric material such as Si(111)\nis usually understood either from the phenomenology theory or more recently\nusing the Simplified Bond-Hyperpolarizability Model (SBHM) [G. D. Powell, J. F.\nWang, and D. E. Aspnes, Phys. Rev. B 65, 205320/1 (2002)]. Although SBHM is\nderived from a classical point of view, it has the advantage over the former\nthat it gives-especially for lower symmetry systems- a clear physical picture\nand a more efficient explanation of how nonlinearity is generated. In this\npaper we provide a step-by-step description of the SBHM in Si(111) for the\nlinear and second harmonic case. We present a SHG experiment of Si(111) and\nshow how it can be modelled by summing up the contribution of the fields\nproduced by the anharmonic motion along the bonds."
    },
    {
        "anchor": "Recent developments in dynamic fracture: Some perspectives: We briefly review a number of important recent experimental and theoretical\ndevelopments in the field of dynamic fracture. Topics include experimental\nvalidation of the equations of motion for straight tensile cracks (in both\ninfinite media and strip geometries), validation of a new theoretical\ndescription of the near-tip fields of dynamic cracks incorporating weak elastic\nnonlinearities, a new understanding of dynamic instabilities of tensile cracks\nin both 2D and 3D, crack front dynamics, and the relation between frictional\nmotion and dynamic shear cracks. Related future research directions are briefly\ndiscussed.",
        "positive": "Giant Effective charges and Piezoelectricity in Gapped Graphene: Since the first realization of reversible charge doping in graphene via\nfield-effect devices, it has become evident how the induction a gap could\nfurther enhance its potential for technological applications. Here we show that\nthe gap opening due to a sublattice symmetry breaking has also a profound\nimpact on the polar response of graphene. By combining ab-initio calculations\nand analytical modelling we show that for realistic band-gap values\n($\\Delta\\lesssim 0.5$ eV) the piezoelectric coefficient and the Born effective\ncharge of graphene attain a giant value, independent on the gap. In particular\nthe piezoelectric coefficient per layer of gapped mono- and bilayer graphene is\nthree times larger than that of a large-gap full polar insulator as hexagonal\nBoron Nitride (h-BN) monolayer, and 30\\% larger than that of a polar\nsemiconductor as MoS$_2$. This surprising result indicates that piezoelectric\nacoustic-phonons scattering can be relevant to model charge transport and\ncharge-carrier relaxation in gated bilayer graphene. The independence of the\npiezoelectric coefficient and of the Born effective charge on the gap value\nfollows from the connection between the polar response and the valley Chern\nnumber of gapped Dirac electrons, made possible by the effective gauge-field\ndescription of the electron-lattice/strain coupling in these systems. In the\nsmall gap limit, where the adiabatic ab-initio approximation fails, we\nimplement analytically the calculation of the dynamical effective charge, and\nwe establish a universal relation between the complex effective charge and the\nso-called Fano profile of the phonon optical peak. Our results provide a\ngeneral theoretical framework to understand and compute the polar response in\nnarrow-gap semiconductors, but may also be relevant for the contribution of\npiezoelectric scattering to the transport properties in Dirac-like systems."
    },
    {
        "anchor": "Magnetic domains without domain walls: a unique effect of He+ ion\n  bombardment in ferrimagnetic Co/Tb multilayers: We show that it is possible to engineer magnetic multi-domain configurations\nwithout domain walls in a prototypical rare earth/transition metal ferrimagnet\nusing keV He+ ion bombardment. We additionally shown that these patterns\ndisplay a particularly stable magnetic configuration due to a deep minimum in\nthe free energy of the system which is caused by flux closure and the\ncorresponding reduction of the magnetostatic part of the total free energy.\nThis is possible because light-ion bombardment differently affects an elements\nrelative contribution to the effective properties of the ferrimagnet. The\nimpact of bombardment is stronger for rare earth elements. Therefore, it is\npossible to influence the relative contributions of the two magnetic subsystems\nin a controlled manner. The selection of material system and the use of\nlight-ion bombardment open a route to engineer domain patterns in continuous\nmagnetic films much smaller than what is currently considered possible.",
        "positive": "Efficient full frequency GW for metals using a multipole approach for\n  the dielectric screening: The properties of metallic systems with important and structured excitations\nat low energies, such as Cu, are challenging to describe with simple models\nlike the plasmon pole approximation (PPA), and more accurate and sometimes\nprohibitive full frequency approaches are usually required. In this paper we\npropose a numerical approach to $GW$ calculations on metals that takes into\naccount the frequency dependence of the screening via the multipole\napproximation (MPA), an accurate and efficient alternative to current\nfull-frequency methods that was recently developed and validated for\nsemiconductors and overcomes several limitations of PPA. We now demonstrate\nthat MPA can be successfully extended to metallic systems by optimizing the\nfrequency sampling for this class of materials and introducing a simple method\nto include the $\\mathbf{q}\\to 0$ limit of the intra-band contributions. The\ngood agreement between MPA and full frequency results for the calculations of\nquasi-particle energies, polarizability, self-energy and spectral functions in\ndifferent metallic systems confirms the accuracy and computational efficiency\nof the method. Finally, we discuss the physical interpretation of the MPA poles\nthrough a comparison with experimental electron energy loss spectra for Cu."
    },
    {
        "anchor": "Electronic phase separation at LaAlO3/SrTiO3 interfaces tunable by\n  oxygen deficiency: Electronic phase separation is crucial for the fascinating macroscopic\nproperties of the LaAlO3/SrTiO3 (LAO/STO) paradigm oxide interface, including\nthe coexistence of superconductivity and ferromagnetism. We investigate this\nphenomenon using angle-resolved photoelectron spectroscopy (ARPES) in the\nsoft-X-ray energy range, where the enhanced probing depth combined with\nresonant photoexcitation allow access to fundamental electronic structure\ncharacteristics (momentum-resolved spectral function, dispersions and ordering\nof energy bands, Fermi surface) of buried interfaces. Our experiment uses X-ray\nirradiation of the LAO/STO interface to tune its oxygen deficiency, building up\na dichotomic system where mobile weakly correlated Ti t2g-electrons co-exist\nwith localized strongly correlated Ti eg-ones. The ARPES spectra dynamics under\nX-ray irradiation shows a gradual intensity increase under constant Luttinger\ncount of the Fermi surface. This fact identifies electronic phase separation\n(EPS) where the mobile electrons accumulate in conducting puddles with fixed\nelectronic structure embedded in an insulating host phase, and allows us to\nestimate the lateral fraction of these puddles. We discuss the physics of EPS\ninvoking a theoretical picture of oxygen-vacancy clustering, promoted by the\nmagnetism of the localized Ti eg-electrons, and repelling of the mobile\nt2g-electrons from these clusters. Our results on the irradiation-tuned EPS\nelucidate the intrinsic one taking place at the stoichiometric LAO/STO\ninterfaces.",
        "positive": "Contribution of the buffer layer to the Raman spectrum of epitaxial\n  graphene on SiC(0001): We report a Raman study of the so-called buffer layer with\n$(6\\sqrt3\\times6\\sqrt3)R30^{\\circ}$ periodicity which forms the intrinsic\ninterface structure between epitaxial graphene and SiC(0001). We show that this\ninterface structure leads to a nonvanishing signal in the Raman spectrum at\nfrequencies in the range of the D- and G-band of graphene and discuss its shape\nand intensity. Ab-initio phonon calculations reveal that these features can be\nattributed to the vibrational density of states of the buffer-layer."
    },
    {
        "anchor": "Investigation on different physical aspects such as structural, elastic,\n  mechanical, optical properties and Debye temperature of Fe2ScM (M = P and As)\n  semiconductors: a DFT based first principles study: With the help of first principles calculation method based on the density\nfunctional theory we have investigated the structural, elastic, mechanical\nproperties and Debye temperature of Fe2ScM (M = P and As) compounds under\npressure up to 60 GPa. The optical properties have been investigated under zero\npressure. Our calculated optimized structural parameters of both the compounds\nare in good agreement with the other theoretical results. The calculated\nelastic constants show that Fe2ScM (M = P and As) compounds are mechanically\nstable up to 60 GPa.",
        "positive": "Epitaxial growth, structural characterization and exchange bias of\n  non-collinear antiferromagnetic Mn$_{3}$Ir thin films: Antiferromagnetic materials are of great interest for spintronics. Here we\npresent a comprehensive study of the growth, structural characterization, and\nresulting magnetic properties of thin films of the non-collinear\nantiferromagnet Mn$_{3}$Ir. Using epitaxial engineering on MgO (001) and\nAl$_{2}$O$_{3}$ (0001) single crystal substrates, we control the growth of\ncubic ${\\gamma}$-Mn$_{3}$Ir in both (001) and (111) crystal orientations, and\ndiscuss the optimization of growth conditions to achieve high-quality crystal\nstructures with low surface roughness. Exchange bias is studied in bilayers,\nwith exchange bias fields as large as -29 mT (equivalent to a unidirectional\nanisotropy constant of 11.5 nJ cm$^{-2}$) measured in Mn$_{3}$Ir (111) /\npermalloy heterostructures at room temperature. In addition, a distinct\ndependence of blocking temperature on in-plane crystallographic direction in\nMn$_{3}$Ir (001) / Py bilayers is observed. These findings are discussed in the\ncontext of chiral antiferromagnetic domain structures, and will inform progress\ntowards topological antiferromagnetic spintronic devices."
    },
    {
        "anchor": "Violations of L\u00f6wensteins rule in zeolites: Zeolites, microporous aluminosilicates, are amongst the most widely used\ncatalysts in the petrochemical industry. Zeolite catalytic functionality is\ncoupled to the distribution of tetrahedral alumina (AlO4-) and associated\ncounter-cations throughout the aluminosilicate framework, yet little is\ndefinitively known about the factors that govern framework aluminium\narrangement. It is generally accepted that all zeolites obey Lowensteins rule\nof aluminium avoidance and that Al-O-Al linkages are forbidden. Here, we\ndescribe the unprecedented screening of aluminium distribution in catalytically\nactive zeolite SSZ-13 in both its protonated and sodium containing forms,\nH-SSZ-13 and Na-SSZ-13, using density functional theory. We predict violations\nof Lowensteins rule in high and low silica H-SSZ-13 and other protonated\nframeworks considered in this investigation, H-LTA, H-RHO and H-ABW. The\nsynthetic realisation of these zeolites could spur the development of new\ncatalytic routes and materials, and the optimisation of existing zeolite\ncatalysts.",
        "positive": "Magnetic and mechanical effects of Mn substitutions in AlFe2B2: The mechanical and magnetic properties of the newly discovered MAB-phase\nclass of materials based upon AlFe2B2 were investigated. The samples were\nsynthesised from stoichiometric amounts of all constituent elements. X-ray\ndiffraction shows that the main phase is orthorhombic with an elongated b-axis,\nsimilar to AlFe2B2. The low hardness and visual inspection of the samples after\ndeformation indicate that these compounds are deformed via a delamination\nprocess. When substituting iron in AlFe2B2 with manganese, the magnetism in the\nsystem goes from being ferro- to antiferromagnetic via a disordered\nferrimagnetic phase exhibited by AlFeMnB2. Density functional theory\ncalculations indicate a weakening of the magnetic interactions among the\ntransitions metal ions as iron is substituted by manganese in AlFe2B2. The\nMn-Mn exchange interactions in AlMn2 B2 are found to be very small."
    },
    {
        "anchor": "Laser-induced torques in metallic antiferromagnets: We study the laser-induced torques in the antiferromagnet (AFM) Mn$_2$Au. We\nfind that even linearly polarized light may induce laser-induced torques in\nMn$_2$Au, i.e., the light does not have to be circularly polarized. The\nlaser-induced torques in Mn$_2$Au are comparable in magnitude to those in the\nferromagnets Fe, Co and FePt at optical frequencies. We also compute the\nlaser-induced torques at terahertz (THz) frequencies and compare them to the\nspin-orbit torques (SOTs) excited by THz laser-pulses. We find the SOTs to be\ndominant at THz frequencies for the laser-field strengths used in experiments.\nAdditionally, we show that the matrix elements of the spin-orbit interaction\n(SOI) can be used to add SOI only during the Wannier interpolation, which we\ncall Wannier interpolation of SOI (WISOI). This technique allows us to perform\nthe Wannier interpolation conveniently for many magnetization directions from a\nsingle set of Wannier functions.",
        "positive": "Electrical spin injection and detection in lateral all-semiconductor\n  devices: Electrical injection and detection of spin-polarized electrons is\ndemonstrated for the first time in a single wafer, all-semiconductor,\nGaAs-based lateral spintronic device, employing p+-(Ga,Mn)As/n+-GaAs\nferromagnetic Esaki diodes as spin aligning contacts. The conversion of\nspin-polarized holes into spin-polarized electrons via Esaki tunnelling leaves\nits mark in a bias dependence of the spin-injection efficiency, which at\nmaximum reaches the relatively high value of 50%."
    },
    {
        "anchor": "Comparing the performance of LDA and GGA functionals in predicting the\n  lattice thermal conductivity of semiconductor materials: the case of AlAs: In this contribution we assess the performance of two different\nexchange-correlation functionals in the first-principle prediction of the\nlattice thermal conductivity of bulk semiconductors, namely the local density\napproximation (LDA) and the Perdew-Burke-Ernzerhof implementation of the\ngeneralized gradient approximation (GGA). Both functionals are shown to give\nresults in good agreement with experimental measurements. Such a consistency\nbetween the two functionals may seem a bit surprising, as the LDA is known to\noverbind and the GGA to soften the interatomic bonds. Such features ought to\ngreatly affect the value of the system interatomic force constants (IFCs) which\nare necessary for the first-principle prediction of the lattice thermal\nconductivity. In this study we show that the errors introduced by such\napproximations tend to cancel themselves. In the case of LDA, the overbinding\ngenerates larger absolute third-order IFCs, which tend to increase the\nthree-phonon scattering rates. On the other hand, larger absolute second-order\nIFCs lead to a a larger acoustic-optical phonon band gap which in turns\ndecrease the available phase space for three-phonon scattering, compensating\nthe increase in the scattering rates due to stiffer IFCs.",
        "positive": "Spin glass state in layered compound MnSb2Te4: As a sister compound and isostructural of MnBi2Te4, the high quality MnSb2Te4\nsingle crystals are grown via solid-state reaction where prolonged annealing\nand narrow temperature window play critical roles on account of its thermal\nmetastability. X-ray diffraction analysis on MnSb2Te4 single crystals reveals\npronounced cation intermixing, 28.9(7)% Sb antisite defects on the Mn (3a) site\nand 19.3(6)% Mn antisite defects on the Sb (6c) site, compared with MnBi2Te4.\nUnlike antiferromagnetic (AFM) nature MnBi2Te4, MnSb2Te4 contains magnetic and\nantiferromagnetic competition and exhibits a spin glass (SG) state below 24 K.\nIts magnetic hysteresis, anisotropy, and relaxation process are investigated in\ndetail with DC and AC magnetization measurements. Moreover, anomalous Hall\neffect as a p-type conductor is demonstrated through transport measurements.\nThis work grants MnSb2Te4 a possible access to the future exploration of exotic\nquantum physics by removing the odd/even layer number restraint in intrinsic\nAFM MnBi2Te4-family materials as a result of the crossover between its\nmagnetism and potential topology in the Sb-Te layer."
    },
    {
        "anchor": "Theory of magnetic enhancement in strontium hexaferrite through Zn-Sn\n  pair substitution: We study the site occupancy and magnetic properties of Zn-Sn substituted\nM-type Sr-hexaferrite SrFe$_{12-x}$(Zn$_{0.5}$Sn$_{0.5}$)$_x$O$_{19}$ with x =\n1 using first-principles total-energy calculations. We find that in a\nground-state configuration Zn-Sn ions preferentially occupy $4f_1$ and $4f_2$\nsites unlike the model previously suggested by Ghasemi et al. [J. Appl. Phys,\n\\textbf{107}, 09A734 (2010)], where Zn$^{2+}$ and Sn$^{4+}$ ions occupy the\n$2b$ and $4f_2$ sites. Density-functional theory calculations show that our\nmodel has a lower total energy by more than 0.2 eV per unit cell compared to\nGhasemi's model. More importantly, the latter does not show an increase in\nsaturation magnetization ($M_s$) compared to the pure $M$-type Sr-hexaferrite,\nin disagreement with the experiment. On the other hand, our model correctly\npredicts a rapid increase in $M_s$ as well as a decrease in magnetic anisotropy\ncompared to the pure $M$-type Sr-hexaferrite, consistent with experimental\nmeasurements.",
        "positive": "Linear magnetoresistance in the low-field limit in density-wave\n  materials: The magnetoresistance (MR) of a material is typically insensitive to\nreversing the applied field direction and varies quadratically with magnetic\nfield in the low-field limit. Quantum effects [1], unusual topological band\nstructures [2], and inhomogeneities that lead to wandering current paths [3, 4]\ncan induce a crossover from quadratic to linear magnetoresistance with\nincreasing magnetic field. Here we explore a series of metallic charge- and\nspin-density-wave systems that exhibit extremely large positive linear\nmagnetoresistance. By contrast to other linear MR mechanisms, this effect\nremains robust down to miniscule magnetic fields of tens of Oersted at low\ntemperature. We frame an explanation of this phenomenon in a semi-classical\nnarrative for a broad category of materials with partially-gapped Fermi\nsurfaces due to density waves."
    },
    {
        "anchor": "Temperature dependence of the interface spin Seebeck effect: We performed temperature-dependent optical pump - THz emission measurements\nin Y3Fe5O12 (YIG)|Pt from 5 K to room temperature in the presence of an\nexternally applied magnetic field. We study the temperature dependence of the\nspin Seebeck effect and observe a continuous increase as temperature is\ndecreased, opposite to what is observed in electrical measurements where the\nspin Seebeck effect is suppressed as 0K is approached. By quantitatively\nanalysing the different contributions we isolate the temperature dependence of\nthe spin-mixing conductance and observe features that are correlated to the\nbands of magnon spectrum in YIG.",
        "positive": "Dislocation Density-Based Plasticity Model from Massive Discrete\n  Dislocation Dynamics Database: We present a dislocation density-based strain hardening model for single\ncrystal copper through a systematic coarse-graining analysis of more than 200\ndiscrete dislocation dynamics (DDD) simulations of plastic deformation under\nuniaxial tension. The proposed constitutive model has two components: a\ngeneralized Taylor relation connecting resolved shear stresses to dislocation\ndensities on individual slip systems, and a generalized Kocks-Mecking model for\ndislocation multiplication. The DDD data strongly suggests a logarithmic\ndependence of flow stress on the plastic shear strain rate on each slip system,\nand, equivalently, an exponential dependence of the plastic shear strain rate\non the resolved shear stress. Hence the proposed generalized Taylor relation\nsubsumes the Orowan relation for plastic flow. The DDD data also calls for a\ncorrection to the Kocks-Mecking model of dislocation multiplication to account\nfor the increase of dislocation density on slip systems with negligible plastic\nshear strain rate. This is accomplished by allowing the multiplication rate on\neach slip system to include contributions from the plastic strain rates of the\ntwo coplanar slip systems. The resulting constitutive model successfully\ncaptures the strain hardening rate dependence on the loading orientation as\npredicted by the DDD simulations, which is also consistent with existing\nexperiments."
    },
    {
        "anchor": "Vacancy Tuned Magnetism in LaMn$_x$Sb$_2$: The layered ATMPn$_2$ (A = alkali earth or rare earth atom, TM = transition\nmetal, Pn = Sb, Bi) compounds are widely studied for their rich magnetism and\nelectronic structure topology. Here, we characterize the physical properties of\nLaMn$_x$Sb$_2$, an understudied member of the ATMPn$_2$ family. LaMn$_x$Sb$_2$\nforms with intrinsic Mn vacancies, and we demonstrate synthetic control of the\nMn occupancy to produce single crystals with x = 0.74-0.97. Magnetization and\ntransport measurements indicate LaMn$_x$Sb$_2$ has a rich\ntemperature-composition (T-x) magnetic phase diagram with physical properties\nstrongly influenced by the Mn occupancy. LaMn$_x$Sb$_2$ orders\nantiferromagnetically at T$_{1}$ = 130--180 K, where T$_{1}$ increases with x.\nBelow T$_{1}$, the T-x phase diagram is complicated. At high x, there is a\nsecond transition T$_2$ that decreases in temperature as x is lowered,\nvanishing below x $\\leq$ 0.85. A third, first-order, transition T$_3$ is\ndetected at x $\\approx$ 0.92, and the transition temperature increases as x is\nlowered, crossing above T$_2$ near x $\\approx$ 0.9. On moving below x $<$ 0.79,\nwe find the crystal structure changes from the P4/nmm arrangement to a\nI$\\bar{4}$2m structure with partially ordered Mn vacancies. The change in\ncrystal structure results in the appearance of two new low temperature phases\nand a crossover between regimes of negative and positive magnetoresistance.\nFinally, we provide neutron diffraction for x = 0.93, and find that the high x\ncompositions first adopt a G-type AFM structure with the Mn moments aligned\nwithin the ab-plane which is followed on cooling by a second transition to a\ndifferent, non-collinear structure where the moments are rotated within the\nbasal plane. Our results demonstrate that LaMn$_x$Sb$_2$ is a highly tunable\nmaterial with six unique magnetically ordered phases, depending on T and x.",
        "positive": "Mode II fracture of an MMA adhesive layer: theory versus experiment: Thick adhesive layers have potential structural application in ship\nconstruction for the joining of a composite superstructure to a steel hull. The\npurpose of this study is to develop a mechanics model for the adhesive fracture\nof such lap joints under shear loading. Modified Thick-Adherend-Shear-Test\n(TAST) specimens made from a MMA-based adhesive and steel adherents are\ndesigned and fabricated. Crack initiation and growth of these joints is\nmeasured and monitored by Digital Image Correlation (DIC). An attempt is made\nto use a cohesive zone model to predict the magnitude of shear strain across\nthe adhesive layer both at crack initiation and at peak load, and to predict\nthe extent of crack growth as a function of shear strain across the adhesive\nlayer. The ability of a cohesive zone model to predict several features of\nspecimen failure is assessed for the case of an adhesive layer of high shear\nductility."
    },
    {
        "anchor": "Atomistic study of electrostatics and carrier transport properties of\n  CNT@MS2 (M= Mo,W) and CNT@BN core-shell nanotubes: In this work we present an ab-initio study of electronic properties of 1\ndimensional (1D) core-shell nanostructures made of MS2 (MoS2, WS2) or BN\narmchair nanotube encapsulated carbon nanotubes (CNT). With local density\napproximation (LDA) in density functional theory (DFT) we calculate the\nbandstructure, carrier effective masses, various fundamental electrostatic\nfeatures and optical absorption in such core-shell tubes. The carrier transport\nin these structures are important for nanoelectronics applications and are\nstudied with the Greens function formalism. Simulations show a moderate\nindirect band gap in the core-shell CNT@MS2 tubes while the CNT@BN shows\nmetallic nature. The varying chirality of CNT strongly affects the carrier\neffective masses of the CNT@MS2 structure. Electron density is found to be much\nmore localized near the atom cores and stronger in magnitude for the CNT@BN\nwhile the W atoms show a more prominent electron-gas presence around them than\nMo atoms as found in the electron localization functions. In the CNT@MS2\nsystems the electrostatic difference potential indicates a drive to transfer\ncharge from the metal to the S atoms in the shell. In terms of optical\nabsorption a strong and sharper peak is observed around 6 eV for the CNT@BN\ncompared to a more broad absorption spectra of the CNT@MS2. Metallic\ntransmission spectra is seen for CNT@BN while CNT@MS2 shows non-metallic\ntransport but with a larger number of transmission states near fermi level. The\nelectronic and optical properties and its possible tuning in the core-shell\nstructures can be useful in various applications such as shielded\ninterconnects, logic switches and optoelectronics.",
        "positive": "Distortion and electric field control of band structure of silicene: Density functional theory with local density approximation for exchange and\ncorrelation functional is used to tune the electronic band structure of\nsilicene monolayer. The cohesive energy of free standing monolayer is\nincreasing (decreasing) with external electric field (distortion). Electrons in\nsilicene behave like Dirac fermions, when the bond angle between the Si atoms\nis larger than $\\sim 102^{0}$. Large distortions destroy the electronic\nstructure of silicene and silicene is no longer a semi-metallic material, and\nthe distorted silicene acts like an $n$-doped system. Electric field opens a\nband gap around $K$ point in the Brillouin zone, which increases with electric\nfield. The bond angle between the Si atoms is a key player to determine the\npresence or absence of Dirac cones in silicene."
    },
    {
        "anchor": "Nonlinear self-collimated sound beams in sonic crystals: We report the propagation of high-intensity sound beams in a sonic crystal,\nunder self-collimation or reduced-divergence conditions. The medium is a fluid\nwith elastic quadratic nonlinearity, where the dominating nonlinear effect is\nharmonic generation. The conditions for the efficient generation of narrow,\nnon-diverging beam of second harmonic are discussed. Numerical simulations are\nin agreement with the analytical predictions made, based on the linear\ndispersion characteristics in modulated media and the nonlinear interaction in\na quadratic medium under phase matching conditions.",
        "positive": "Locally Resonant Granular Chain: We report the design and testing of a tunable and nonlinear mechanical\nmetamaterial, called locally resonant granular chain. It consists of a\none-dimensional array of hollow spherical particles in contact, containing\nlocal resonators. The resonant particles are made of an aluminium outer\nspherical shell and a steel inner mass connected by a polymeric plastic\nstructure acting as a spring. We characterize the linear spectra of the\nindividual particles and of one-dimensional arrays of particles using theory,\nnumerical analysis, and experiments. A wide band gap is observed as well as\ntunability of the dispersive spectrum by changing the applied static load.\nFinally, we experimentally explore the nonlinear dynamics of the resonant\nparticles. By using nonlinear acoustical techniques, we reveal a complex,\nnonclassical nonlinear dynamics."
    },
    {
        "anchor": "Defect scattering in graphene: Irradiation of graphene on SiO2 by 500 eV Ne and He ions creates defects that\ncause intervalley scattering as evident from a significant Raman D band\nintensity. The defect scattering gives a conductivity proportional to charge\ncarrier density, with mobility decreasing as the inverse of the ion dose. The\nmobility decrease is four times larger than for a similar concentration of\nsingly charged impurities. The minimum conductivity decreases proportional to\nthe mobility to values lower than 4e^2/(pi*h), the minimum theoretical value\nfor graphene free of intervalley scattering. Defected graphene shows a\ndiverging resistivity at low temperature, indicating insulating behavior. The\nresults are best explained by ion-induced formation of lattice defects that\nresult in mid-gap states.",
        "positive": "Crystal Growth in the Presence of Surface Melting: Novel Behavior of the\n  Principal Facets of Ice: We present measurements of the growth rates of the principal facet surfaces\nof ice from water vapor as a function of supersaturation over the temperature\nrange -2 C > T > -40 C. Our data are well described by a dislocation-free\nlayer-nucleation model, parameterized by the attachment coefficient as a\nfunction of supersaturation \\alpha(\\sigma) = Aexp(-\\sigma_0/\\sigma). The\nmeasured parameters A(T) and \\sigma_0(T) for the basal and prism facets exhibit\na complex behavior that likely originates from structural changes in the ice\nsurface with temperature, in particular the onset and development of surface\nmelting for T > -15 C. From \\sigma_0(T) we extract the terrace step energy\n\\beta(T) as a function of temperature for both facet surfaces. As a basic\nproperty of the equilibrium ice surface, the step energy \\beta(T) may be\namenable to calculation using molecular dynamics simulations, potentially\nyielding new insights into the enigmatic surface structure of ice near the\ntriple point."
    },
    {
        "anchor": "Two-Dimensional Van der Waals Epitaxy Kinetics in a Three-Dimensional\n  Perovskite Halide: The exploration of emerging materials physics and prospective applications of\ntwo-dimensional materials greatly relies on the growth control of their\nthickness, phases, morphologies and film-substrate interactions. Though\nsubstantial progresses have been made for the development of two-dimensional\nfilms from conventional layered bulky materials, particular challenges remain\non obtaining ultrathin, single crystalline, dislocation-free films from\nintrinsically non-Van der Waals-type three-dimensional materials. In this\nreport, with the successful demonstration of single crystalline ultrathin large\nscale perovskite halide material, we reveal and identify the favorable role of\nweak Van der Waals film-substrate interaction on the nucleation and growth of\nthe two-dimensional morphology out of non-layered materials compared to\nconventional epitaxy. We also show how the bonding nature of the\nthree-dimensional material itself affects the kinetic energy landscape of\nultrathin films growth. By studying the formation of fractal perovskites\nassisted with Monte Carlo simulations, we demonstrate that the competition\nbetween the Van der Waals diffusion and surface free energy of the perovskite\nleads to film thickening, suggesting extra strategies such as surface\npassivation may be needed for the growth of monolayer and a few layers films.",
        "positive": "On magnetic structure of CuFe2Ge2: constrains from the 57Fe Mossbauer\n  spectroscopy: 57Fe Mossbauer spectroscopy measurements were performed on a powdered\nCuFe2Ge2 sample that orders antiferromagnetically at ~ 175 K. Whereas a\nparamagnetic doublet was observed above the Neel temperature, a superposition\nof paramagnetic doublet and magnetic sextet (in approximately 0.5 : 0.5 ratio)\nwas observed in the magnetically ordered state, suggesting a magnetic structure\nsimilar to a double-Q spin density wave with half of the Fe paramagnetic and\nanother half bearing static moment of ~ 0.5 - 1 mu_B. These results call for a\nre-evaluation of the recent neutron scattering data and band structure\ncalculations."
    },
    {
        "anchor": "Lattice dynamics and ferroelectric properties of the nitride perovskite\n  ${\\mathrm{LaWN}}_{3}$: Using first-principles calculations we examine the crystal structures and\nphase transitions of nitride perovskite LaWN$_3$. Lattice dynamics calculations\nindicate that the ground-state structure belongs to space group $R3c$. Two\ncompetitive phase transition pathways are identified which are characterized by\nsymmetry-adapted distortion modes. The results suggest that $R3c$ LaWN$_3$\nshould be an excellent ferroelectric semiconductor: its large spontaneous\npolarization of around 61 $\\mu$C/cm$^2$ is comparable to that of PbTiO$_3$, and\nits band gap is about 1.72 eV. Ferroelectricity is found to result from the\n\\emph{B}-site instability driven by hybridization between W-5$d$ and N-2$p$\norbitals. These properties make LaWN$_3$ an attractive candidate material for\nuse in ferroelectric memory devices and photovoltaic cells.",
        "positive": "Freezing of a disorder induced quantum spin liquid: $\\rm{Sr_2CuTe_{0.5}W_{0.5}O_6}$ is a square-lattice magnet with\nsuper-exchange between S=1/2 $\\rm{Cu^{2+}}$ spins mediated by randomly\ndistributed Te and W ions. Here, using sub-K temperature and 20 $\\rm{\\mu}$eV\nenergy resolution neutron scattering experiments we show that this system\ntransits from a gapless disorder-induced quantum spin liquid to a new quantum\nstate below $\\rm{T_f}$ = 1.7(1) K, exhibiting a weak frozen moment of <S>/S ~\n0.1 and low energy dynamic susceptibility,${\\chi}''({\\hbar\\omega})$ linear in\nenergy which is surprising for such a weak freezing in this highly fluctuating\nquantum regime."
    },
    {
        "anchor": "Revealing multiple classes of stable quantum emitters in hexagonal boron\n  nitride with correlated cathodoluminescence, photoluminescence, and strain\n  mapping: Single photon emitters (SPEs) in solids have emerged as promising candidates\nfor quantum photonic sensing, communications, and computing. Defects in\nhexagonal boron nitride (hBN) exhibit high-brightness, room-temperature quantum\nemission, but their large spectral variability and unknown local structure\nsignificantly challenge their technological utility. Here, we directly\ncorrelate hBN quantum emission with the material's local strain using a\ncombination of photoluminescence (PL), cathodoluminescence (CL) and nano-beam\nelectron diffraction. Across 40 emitters and 15 samples, we observe zero phonon\nlines(ZPLs) in PL and CL ranging from 540-720 nm. CL mapping reveals that\nmultiple defects and distinct defect species located within an\noptically-diffraction-limited region can each contribute to the observed PL\nspectra. Local strain maps indicate that strain is not required to activate the\nemitters and is not solely responsible for the observed ZPL spectral range.\nInstead, four distinct defect classes are responsible for the observed emission\nrange. One defect class has ZPLs near 615 nm with predominantly matched CL-PL\nresponses; it is not a strain-tuned version of another defect class with ZPL\nemission centered at 580 nm. A third defect class at 650 nm has low\nvisible-frequency CL emission; and a fourth defect species centered at 705 nm\nhas a small, ~10 nm shift between its CL and PL peaks. All studied defects are\nstable upon both electron and optical irradiation. Our results provide an\nimportant foundation for atomic-scale optical characterization of color\ncenters, as well as a foundation for engineering defects with precise emission\nproperties.",
        "positive": "Magnetic and Structural Phase Transitions in the Spinel Compound\n  Fe1+xCr2-xO4: Neutron and X-ray diffraction, magnetic susceptibility, and specific heat\nmeasurements have been used to investigate the magnetic and structural phase\ntransitions of the spinel system Fe1+xCr2-xO4(0.0<=x<=1.0). The temperature\nversus Fe concentration (x) phase diagram features two magnetically ordered\nstates and four structural states below 420 K. The complexity of the phase\ndiagram is closely related to the change in the spin and orbital degrees of\nfreedom induced by substitution of Fe ions for Cr ions. The systematic change\nin the crystal structure is explained by the combined effects of Jahn-Teller\ndistortion, spin-lattice interaction, Fe2+-Fe3+ hopping, and disorder among\nFe2+, Fe3+, and Cr3+ ions."
    },
    {
        "anchor": "Experimental study of electron and phonon dynamics in nanoscale\n  materials by ultrafast laser time-domain spectroscopy: With the rapid advances in the development of nanotechnology, nowadays, the\nsizes of elementary unit, i.e. transistor, of micro- and nanoelectronic devices\nare well deep into nanoscale. For the pursuit of cheaper and faster nanoscale\nelectronic devices, the size of transistors keeps scaling down. As the\nminiaturization of the nanoelectronic devices, the electrical resistivity\nincreases dramatically, resulting rapid growth in the heat generation. The heat\ngeneration and limited thermal dissipation in nanoscale materials have become a\ncritical problem in the development of the next generation nanoelectronic\ndevices. Copper (Cu) is widely used conducting material in nanoelectronic\ndevices, and the electron-phonon scattering is the dominant contributor to the\nresistivity in Cu nanowires at room temperature. Meanwhile, phonons are the\nmain carriers of heat in insulators, intrinsic and lightly doped\nsemiconductors. The thermal transport is an ensemble of phonon transport, which\nstrongly depends on the phonon frequency. In addition, the phonon transport in\nnanoscale materials can behave fundamentally different than in bulk materials,\nbecause of the spatial confinement. However, the size effect on electron-phonon\nscattering and frequency dependent phonon transport in nanoscale materials\nremain largely unexplored, due to the lack of suitable experimental techniques.\nThis thesis is mainly focusing on the study of carrier dynamics and acoustic\nphonon transport in nanoscale materials.",
        "positive": "Biomimetic surface structuring using cylindrical vector femtosecond\n  laser beams: We report on a new, single-step and scalable method to fabricate highly\nordered, multi-directional and complex surface structures that mimic the unique\nmorphological features of certain species found in nature. Biomimetic surface\nstructuring was realized by exploiting the unique and versatile angular profile\nand the electric field symmetry of cylindrical vector (CV) femtosecond (fs)\nlaser beams. It is shown that, highly controllable, periodic structures\nexhibiting sizes at nano-, micro- and dual-scale micro and nano scales can be\ndirectly written on Ni upon line and large area scanning with radial and\nazimuthal polarization beams. Depending on the irradiation conditions, new\ncomplex multi-directional nanostructures, inspired by the Shark skin\nmorphology, as well as superhydrophobic dual-scale structures mimicking the\nLotus leaf water repellent properties can be attained. It is concluded that the\nversatility and features variations of structures formed upon scanning with CV\nbeams is by far superior to those obtained via laser processing with linearly\npolarized beams. More important, by exploiting the capabilities offered by fs\nCV optical fields, the present technique can be further extended to fabricate\neven more complex and unconventional structures. We believe that our approach\nprovides a new concept in laser processing of materials, which can be further\nexploited for expanding the breadth and novelty of potential applications."
    },
    {
        "anchor": "Field-induced metal-to-insulator transition and colossal anisotropic\n  magnetoresistance in a nearly Dirac material EuMnSb$_2$: How to realize applicably appreciated functionalities based on the coupling\nbetween charge and spin degrees of freedom is still a challenge in the field of\nspintronics. For example, anisotropic magnetoresistance (AMR) effect is\nutilized to read out the information stored by various magnetic structures,\nwhich usually originates from atomic spin-orbit coupling (SOC). However, the\napplication of AMR in antiferromagnet-based spintronics is still hindered by\nrather small AMR value. Here, we discover a colossal AMR effect during the\nfield-induced metal-to-insulator transition (MIT) in a nearly Dirac material\nEuMnSb$_2$ with an antiferromagnetic order of Eu$^{2+}$ moments. The colossal\nAMR reaches to an unprecedented value of 1.84$\\times$10$^6$% at 2 K, which is\nfour orders of magnitude larger than previously reported values in\nantiferromagnets. Based on density functional theory calculations, a Dirac-like\nband structure, which is strongly dependent on SOC, is confirmed around Y point\nand dominates the overall transport properties in the present sample with\npredominant electron-type carriers. Moreover, it is also revealed that the\nindirect band gap around Fermi level is dependent on the magnetic structure of\nEu$^{2+}$ moments, which leads to the field-induced MIT and plays a key role on\nthe colossal AMR effect. Finally, our present work suggests that the similar\nantiferromagnetic topological materials as EuMnSb$_2$, in which Dirac-like\nfermions is strongly modulated by SOC and antiferromagnetism, would be a\nfertile ground to explore applicably appreciated AMR effect.",
        "positive": "The general electronic principle driving size-dependent surface chemical\n  activities of nanomaterials: Size can widely affect the surface chemical activities (SCAs) of\nnanomaterials in chemisorption, catalysis, surface effects, etc., but the\nunderlying electronic nature has long remained mysterious. We report a general\nelectronic principle that drives the origin of size-dependent SCAs by combining\nexperimental probing and theoretical modeling. Using the chemisorption of H2O2\non TiO2 as a model reaction, we experimentally reveal that the central\nelectronic process of surface chemical interactions lies in the competitive\nredistribution of surface atomic orbitals from energy band states into surface\ncoordination bonds. By defining orbital potential, a site-dependent intrinsic\nelectronic property that determines surface activities, we further establish a\nmathematical model to uncover the physical nature of how structural factors\ncorrelate to SCAs, particularly the roles of size. We discover that the\nelectronic nature of size effect lies in its inverse correlation to orbital\npotential and amplification effect on other structural factors like defects and\ncoordination numbers."
    },
    {
        "anchor": "A novel self-locked energy absorbing system: Metallic thin-walled round tubes are widely used as energy absorption\nelements. However, lateral splash of the round tubes under impact loadings\nreduces the energy absorption efficiency and may cause secondary damages.\nTherefore, it is necessary to assemble and fasten round tubes together by\nboundary constraints and/or fasteners between tubes, which increases the time\nand labor cost and affects the mechanical performance of round tubes. In an\neffort to break through this limitation, a novel self-locked energy-absorbing\nsystem has been proposed in this paper. The proposed system is made up of\nthin-walled tubes with dumbbell-shaped cross section, which are specially\ndesigned to interlock with each other and thus provide lateral constraint under\nimpact loadings. Both finite element simulations and impact experiment\ndemonstrated that without boundary constraints or fasteners between tubes, the\nproposed self-locked energy-absorbing system can still effectively attenuate\nimpact loads while the round tube systems fail to carry load due to the lateral\nsplashing of tubes. Furthermore, the optimal geometric design for a single\ndumbbell-shaped tube and the optimal stacking arrangement for the system are\ndiscussed, and a general guideline on the structural design of the proposed\nself-locked energy absorbing system is provided.",
        "positive": "Extended point defects in crystalline materials: Ge and Si: B diffusion measurements are used to probe the basic nature of\nself-interstitial 'point' defects in Ge. We find two distinct self-interstitial\nforms - a simple one with low entropy and a complex one with entropy ~30 k at\nthe migration saddle point. The latter dominates diffusion at high temperature.\nWe propose that its structure is similar to that of an amorphous pocket - we\nname it a 'morph'. Computational modelling suggests that morphs exist in both\nself-interstitial and vacancy-like forms, and are crucial for diffusion and\ndefect dynamics in Ge, Si and probably many other crystalline solids."
    },
    {
        "anchor": "Surface states in bulk single crystal of topological semimetal\n  Co$_3$Sn$_2$S$_2$ towards water oxidation: The band inversion in topological phase matters bring exotic physical\nproperties such as the emergence of a topologically protected surface states.\nThey strongly influence the surface electronic structures of the investigated\nmaterials and could serve as a good platform to gain insight into the catalytic\nmechanism of surface reactions. Here we synthesized high-quality bulk single\ncrystals of the topological semimetal Co$_3$Sn$_2$S$_2$. We found that at room\ntemperature, Co$_3$Sn$_2$S$_2$ naturally hosts the band structure of a\ntopological semimetal. This guarantees the existence of robust surface states\nfrom the Co atoms. Bulk single crystal of Co$_3$Sn$_2$S$_2$ exposes their\nKagome lattice that constructed by Co atoms and have high electrical\nconductivity. They serves as catalytic centers for oxygen evolution process\n(OER), making bonding and electron transfer more efficient due to the partially\nfilled $e_g$ orbital. The bulk single crystal exhibits outstanding OER\ncatalytic performance, although the surface area is much smaller than that of\nCo-based nanostructured catalysts. Our findings emphasize the importance of\ntailoring topological non-trivial surface states for the rational design of\nhigh-activity electrocatalysts.",
        "positive": "Revisiting step instabilities on crystal surfaces. Part II: General\n  theory: The quasistatic approximation is a useful but questionable simplification for\nanalyzing step instabilities during the growth/evaporation of vicinal surfaces.\nUsing this approximation, we characterized in Part I of this work the effect on\nstability of different mechanisms and their interplay: elastic step-step\ninteractions, the Schwoebel barrier, and the chemical coupling of the diffusion\nfields on adjacent terraces. In this second part, we present a stability\nanalysis of the general problem without recourse to the quasistatic\napproximation. This analysis reveals the existence of a supplementary\nmechanism, which we label the \"dynamics effect\" as it follows from accounting\nfor all the convective and transient terms in the governing equations. This\neffect can be stabilizing or destabilizing depending on the ratio of step\nattachment/detachment kinetics to terrace diffusion kinetics. Further, we find\nthat this dynamics effect remains significant in the slow\ndeposition/evaporation regime, thereby invalidating the classical postulate\nunderlying the quasistatic approximation. Finally, revisiting experiments of\ncrystal growth on Si(111)-7x7 and GaAs(001), our analysis provides an\nalternative explanation of the observed step bunching, one that does not\nrequire the mechanisms previously invoked in the literature."
    },
    {
        "anchor": "Ab-Initio Molecular Dynamics Acceleration Scheme with an Adaptive\n  Machine Learning Framework: Quantum mechanics based ab-initio molecular dynamics (MD) simulation schemes\noffer an accurate and direct means to monitor the time-evolution of materials.\nNevertheless, the expensive and repetitive energy and force computations\nrequired in such simulations lead to significant bottlenecks. Here, we lay the\nfoundations for such an accelerated ab-initio MD approach integrated with a\nmachine learning framework. The proposed algorithm learns from previously\nvisited configurations in a continuous and adaptive manner on-the-fly, and\npredicts (with chemical accuracy) the energies and atomic forces of a new\nconfiguration at a minuscule fraction of the time taken by conventional\nab-initio methods. Key elements of this new accelerated ab-initio MD paradigm\ninclude representations of atomic configurations by numerical fingerprints, the\nlearning algorithm, a decision engine that guides the choice of the prediction\nscheme, and requisite amount of ab-initio data. The performance of each aspect\nof the proposed scheme is critically evaluated for Al in several different\nchemical environments. This work can readily be extended to address\nnon-elemental compounds, and has enormous implications beyond ab-initio MD\nacceleration. It can also lead to accelerated structure and property prediction\nschemes, and accurate force-fields.",
        "positive": "Phonon and crystal field excitations in geometrically frustrated rare\n  earth titanates: The phonon and crystal field excitations in several rare earth titanate\npyrochlores are investigated. Magnetic measurements on single crystals of\nGd2Ti2O7, Tb2Ti2O7, Dy2Ti2O7 and Ho2Ti2O7 are used for characterization, while\nRaman spectroscopy and terahertz time domain spectroscopy are employed to probe\nthe excitations of the materials. The lattice excitations are found to be\nanalogous across the compounds over the whole temperature range investigated\n(295-4 K). The resulting full phononic characterization of the R2Ti2O7\npyrochlore structure is then used to identify crystal field excitations\nobserved in the materials. Several crystal field excitations have been observed\nin Tb2Ti2O7 in Raman spectroscopy for the first time, among which all of the\npreviously reported excitations. The presence of additional crystal field\nexcitations, however, suggests the presence of two inequivalent Tb3+ sites in\nthe low temperature structure. Furthermore, the crystal field level at\napproximately 13 cm-1 is found to be both Raman and dipole active, indicating\nbroken inversion symmetry in the system and thus undermining its current\nsymmetry interpretation. In addition, evidence is found for a significant\ncrystal field-phonon coupling in Tb2Ti2O7. These findings call for a careful\nreassessment of the low temperature structure of Tb2Ti2O7, which may serve to\nimprove its theoretical understanding."
    },
    {
        "anchor": "Exchange coupling and magnetoresistance in CoFe/NiCu/CoFe spin-valves\n  near the Curie point of the spacer: Thermal control of exchange coupling between two strongly ferromagnetic\nlayers through a weakly ferromagnetic Ni-Cu spacer and the associated\nmagnetoresistance is investigated. The spacer, having a Curie point slightly\nabove room temperature, can be cycled between its paramagnetic and\nferromagnetic states by varying the temperature externally or using joule\nheating. It is shown that the giant magnetoresistance vanishes due to a strong\nreduction of the mean free path in the spacer at above ~30 % Ni concentration\n-- before the onset of ferromagnetism. Finally, a device is proposed and\ndemonstrated which combines thermally controlled exchange coupling and large\nmagnetoresistance by separating the switching and the read out elements.",
        "positive": "Structural, magnetic, and optical properties of zinc- and copper-\n  substituted nickel ferrite nanocrystals: Ferrite nanocrystals are interesting material due to their rich physical\nproperties. Here we add nonmagnetic dopants Zn and Cu to nickel ferrite\nnanocrystals, Ni1-xMxFe2O4 (0<=x<=1, M{\\in}{Cu, Zn}), and characterize how\nrelevant properties of the samples are modified accordingly. Basically, these\ndopings cause a rearrangement of Fe+3 ions into the two preexisting octahedral\nand tetrahedral sites. In fact, this, we show, induces pertinent magnetic\nproperties of the doped samples. In the case of the Cu-doping, the Jahn-Teller\neffect also emerges, which we identify through the FTIR Spectroscopy of the\nsamples. Moreover, we show an increase in the lattice parameters of the doped\nsamples, as well a superparamagnetic behavior for the doped samples is shown,\nwhile the Jahn-Teller effect precludes a similar behavior in the CuFe2O4\nnanocrystals. The influences of Zn and Cu substitutions are investigated on the\noptical properties of nickel ferrite nanocrystals by photoluminescence\nmeasurement at room temperature."
    },
    {
        "anchor": "Fluctuation - induced nucleation and dynamics of the kinks on\n  dislocation. Soliton and oscillation regimes in 2D Frenkel-Kontorova model: Numerical simulation of the dislocation motion in 2D Frenkel - Kontorova (FK)\nmodel in the thermostat shows an unusual dynamical behavior. It appears that\n''kink'' regime of dislocation gliding takes place in a certain region of\nparameters of the model but, in disagreement with the common views about the\ndislocation motion under plastic deformation condition, the kinks appear to be\nsimilar to sine-Gordon solitons despite the discreteness of the lattice,\ndamping and thermal fluctuations. At high enough stresses and temperatures the\nmotion of the dislocation is accompanied by its oscillations rather than kink\nnucleation.",
        "positive": "First principles investigation of anionic redox in bisulfate lithium\n  battery cathodes: The search for an alternative high-voltage polyanionic cathode material for\nLi-ion batteries is vital to improve the energy densities beyond the\nstate-of-the-art, where sulfate frameworks form an important class of\nhigh-voltage cathode materials due to the strong inductive effect of the\nS$^{6+}$ ion. Here, we have investigated the mechanism of cationic and/or\nanionic redox in Li$_x$M(SO$_4$)$_2$ frameworks (M = Mn, Fe, Co, and Ni and 0\n$\\leq$ x $\\leq$ 2) using density functional calculations. Specifically, we have\nused a combination of Hubbard $U$ corrected strongly constrained and\nappropriately normed (SCAN+$U$) and generalized gradient approximation\n(GGA+$U$) functionals to explore the thermodynamic (polymorph stability),\nelectrochemical (intercalation voltage), geometric (bond lengths), and\nelectronic (band gaps, magnetic moments, charge populations, etc.) properties\nof the bisulfate frameworks considered. Importantly, we find that the anionic\n(cationic) redox process is dominant throughout delithiation in the Ni (Mn)\nbisulfate, as verified using our calculated projected density of states, bond\nlengths, and on-site magnetic moments. On the other hand, in Fe and Co\nbisulfates, cationic redox dominates the initial delithiation (1 $\\leq$ x\n$\\leq$ 2), while anionic redox dominates subsequent delithiation (0 $\\leq$ x\n$\\leq$ 2). In addition, evaluation of the crystal overlap Hamilton population\nreveals insignificant bonding between oxidizing O atoms throughout the\ndelithiation process in the Ni bisulfate, indicating robust battery performance\nthat is resistant to irreversible oxygen evolution. Finally, we observe both\nGGA+$U$ and SCAN+$U$ predictions are in qualitative agreement for the various\nproperties predicted. Our work should open new avenues for exploring lattice\noxygen redox in novel high voltage polyanionic cathodes, especially using the\nSCAN+$U$ functional."
    },
    {
        "anchor": "Density Functional Study of the L1_0 - alpha-IrV Transition in IrV and\n  RhV: Both IrV and RhV crystallize in the alpha-IrV structure, with a transition to\nthe higher symmetry L1_0 structure at high temperature, or with the addition of\nexcess Ir or Rh. Here we present evidence that this transition is driven by the\nlowering of the electronic density of states at the Fermi level of the\nalpha-IrV structure. The transition has long been thought to be second order,\nwith a simple doubling of the L1_0 unit cell due to an unstable phonon at the R\npoint (0 1/2 1/2). We use first-principles calculations to show that all\nphonons at the R point are, in fact, stable, but do find a region of reciprocal\nspace where the L1_0 structure has unstable (imaginary frequency) phonons. We\nuse the frozen phonon method to examine two of these modes, relaxing the\nstructures associated with the unstable phonon modes to obtain new structures\nwhich are lower in energy than L1_0 but still above alpha-IrV. We examine the\nphonon spectra of these structures as well, looking for instabilities, and find\nfurther instabilities, and more relaxed structures, all of which have energies\nabove the alpha-IrV phase. In addition, we find that all of the relaxed\nstructures, stable and unstable, have a density comparable to the L1_0 phase\n(and less than the alpha-IrV phase), so that any transition from one of these\nstructures to the ground state will have a volume change as well as an energy\ndiscontinuity. We conclude that the transition from L1_0 to alpha-IrV is\nprobably weakly first order.",
        "positive": "Large scale GW-BSE calculations with N3 scaling: excitonic effects in\n  dye sensitised solar cells: Excitonic effects due to electron-hole coupling play a fundamental role in\nrenormalising energy levels in dye sensitised and organic solar cells\ndetermining the driving force for electron extraction. We show that\nfirst-principles calculations based on many-body perturbation theory within the\nGW-BSE approach provide a quantitative picture of interfacial excited state\nenergetics in organic dye-sensitized TiO2 , delivering a general rule for\nevaluating relevant energy levels.To perform GW-BSE calculations in such large\nsystems we introduce a new scheme based on maximally localized Wannier\nfunctions. With this method the overall scaling of GW-BSE calculations is\nreduced from O(N4) to O(N3)."
    },
    {
        "anchor": "Hole spin relaxation in [001] strained asymmetric Si/SiGe and Ge/SiGe\n  quantum wells: Hole spin relaxation in [001] strained asymmetric Si/Si$_{0.7}$Ge$_{0.3}$\n(Ge/Si$_{0.3}$Ge$_{0.7}$) quantum wells is investigated in the situation with\nonly the lowest hole subband being relevant. The effective Hamiltonian of the\nlowest hole subband is obtained by the subband L\\\"owdin perturbation method in\nthe framework of the six-band Luttinger ${\\bf k}\\cdot{\\bf p}$ model, with\nsufficient basis functions included. The lowest hole subband in Si/SiGe quantum\nwells is light-hole like with the Rashba spin-orbit coupling term depending on\nmomentum both linearly and cubically, while that in Ge/SiGe quantum wells is a\nheavy hole state with the Rashba spin-orbit coupling term depending on momentum\nonly cubically. The hole spin relaxation is investigated by means of the fully\nmicroscopic kinetic spin Bloch equation approach, with all the relevant\nscatterings considered. It is found that the hole-phonon scattering is very\nweak, which makes the hole-hole Coulomb scattering become very important. The\nhole system in Si/SiGe quantum wells is generally in the strong scattering\nlimit, while that in Ge/SiGe quantum wells can be in either the strong or the\nweak scattering limit. The Coulomb scattering leads to a peak in both the\ntemperature and hole density dependences of spin relaxation time in Si/SiGe\nquantum wells, located around the crossover between the degenerate and\nnondegenerate regimes. Nevertheless, the Coulomb scattering leads to not only a\npeak but also a valley in the temperature dependence of spin relaxation time in\nGe/SiGe quantum wells.... (The remaining is omitted due to the limit of space).",
        "positive": "Configurations of the third nearest-neighbor molecules forming a vacancy\n  wall and an addition of a CO2 molecule in the vacancy of solid CO2 at T = 0,\n  100, and 200 K studied by Monte Carlo simulation technique: Configurations of the molecules on the wall of a vacancy, formed by removing\na central and its first and second nearest-neighbor (NN) molecules in solid CO2\nwith the Pa3 structure, were calculated by the Monte Carlo simulation technique\nat T = 0, 100, and 200 K and a nominal pressure of P = 1 bar. It was found that\nthe deviations of both the center-of-mass and the orientational coordinates of\nthe molecules from the unperturbed coordinates had a three-fold symmetry about\na body diagonal axis of the crystal. It was also found that a single CO2\nmolecule, initially placed in the center of the vacancy, was stabilized at a\nposition close to the vacancy wall. This paper is a continuation of\narXiv:1711.04976 [cond-mat.mtrl-sci] (2017) and arXiv:1809.04291\n[cond-mat.mtrl-sci] (2018)."
    },
    {
        "anchor": "High temperature equilibrium of 3D and 2D chalcogenide perovskites: Chalcogenide perovskites have been recently under the researchers spotlight\nas novel absorber materials for photovoltaic applications. BaZrS$_3$, the most\ninvestigated compound of this family, shows a high absorption coefficient, a\nbandgap of around 1.8 eV, and excellent environmental and thermal stability. In\naddition to the 3D perovskite BaZrS$_3$, the Ba-Zr-S compositional space\ncontains various 2-D Ruddlesden-Popper phases Ba$_{x+1}$Zr$_x$S$_{3x+1}$ (with\n$x=$ 1, 2, 3) which have recently been reported. In this work it will be shown\nthat at high temperature the Gibbs free energies of 3D and 2D perovskites are\nvery close, suggesting that 2D phases can be easily formed at high\ntemperatures. The analysis of the product of the BaS and ZrS$_2$ solid-state\nreaction, in different stoichiometric conditions, present a mixture of\nBaZrS$_3$ and Ba$_4$Zr$_3$S$_{10}$. To carefully resolve the composition, XRD,\nSEM and EDS analysis were complemented with Raman spectroscopy. For this\npurpose, the phonon modes, and the consequent Raman spectra, were calculated\nfor the 3D and 2D chalcogenide perovskites, as well as for the binary\nprecursors. This thorough characterization demonstrates the thermodynamic\nlimitations and experimental difficulties in forming phase-pure chalcogenide\nperovskites through solid state synthesis, and the importance of using multiple\ntechniques to soundly resolve the composition of these chalcogenide materials.",
        "positive": "Modulational instability and solitons in excitonic semiconductor\n  waveguides: Nonlinear light propagation in a single-mode micron-size waveguide made of\nsemiconducting excitonic material has been theoretically studied in terms of\nexciton-polaritons by using an analysis based on macroscopic fields. When a\nlight pulse is spectrally centered in the vicinity of the ground-state Wannier\nexciton resonance, it interacts with the medium nonlinearly. This optical cubic\nnonlinearity is caused by the repulsive exciton-exciton interactions in the\nsemiconductor, and at resonance it is orders of magnitude larger than the Kerr\nnonlinearity (e.g., in silica). We demonstrate that a very strong and\nunconventional modulational instability takes place, which has not been\npreviously reported. After reducing the problem to a single nonlinear\nSchr\\\"odinger-like equation, we also explore the formation of solitary waves\nboth inside and outside the polaritonic gap and find evidence of spectral\nbroadening. A realistic physical model of the excitonic waveguide structure is\nproposed."
    },
    {
        "anchor": "Polarization Morphology and Electrocaloric Response of Strained\n  Ferroelectric Core-Shell Nanorods and Nanowires: Using Landau-Ginzburg-Devonshire (LGD) approach we proposed the analytical\ndescription of the Vegard strains influence on the spontaneous polarization and\nelectrocaloric response in ferroelectric core-shell nanorods. The nanorod core\npresents a defect-free single-crystalline ferroelectric material, and the\nVegard strains are induced by elastic defects in the ultra-thin shell. The\nfinite element modeling (FEM) based on the LGD approach reveals transitions of\ndomain structure morphology induced by the Vegard strains in the BaTiO3\nnanorods. Namely, tensile Vegard strains induce and support the single-domain\nstate in the central part of the nanorod, while the curled domain structures\nappear near the unscreened or partially screened ends of the rod. The\nvortex-like domains propagate toward the central part of the rod and fill it\nentirely, when the rod is covered by a shell with compressive Vegard strains\nabove some critical value. The critical value depends on the nanorod sizes,\naspect ratio, and screening conditions at its ends. Both analytical theory and\nFEM predict that the tensile Vegard strains in the shell increase the nanorod\npolarization, lattice tetragonality, and electrocaloric response well-above the\nvalues corresponding to the bulk material. The physical reason of the increase\nis the strong electrostriction coupling between the mismatch-type elastic\nstrains induced in the core by the Vegard strains in the shell. Comparison with\nthe earlier XRD data confirmed an increase of tetragonality ratio in tensiled\nBaTiO3 nanorods compared to the bulk material. Obtained analytical expressions,\nwhich are suitable for the description of strain-induced changes in a wide\nclass of multiaxial ferroelectric core-shell nanorods and nanowires, can be\nuseful for strain engineering of advanced ferroelectric nanomaterials for\nelectrocaloric applications and negative capacitance elements.",
        "positive": "Performance-based screening of porous materials for carbon capture: Computational screening methods have been accelerating discovery of new\nmaterials and deployment of technologies based on them in many areas from\nbatteries and alloys to photovoltaics and separation processes. In this review,\nwe focus on post-combustion carbon capture using adsorption in porous\nmaterials. Prompted by unprecedented developments in material science,\nresearchers in material engineering, molecular simulations, and process\nmodelling have been interested in finding the best materials for carbon capture\nusing energy efficient pressure-swing adsorption processes. Recent efforts have\nbeen directed towards development of new multiscale and performance-based\nscreening workflows where we are able to go from the atomistic structure of an\nadsorbent to its equilibrium and transport properties for gas adsorption, and\neventually to its separation performance in the actual process. The objective\nof this article is to review the current status of these emerging approaches,\nexplain their significance for materials screening, while at the same time\nhighlighting the existing pitfalls and challenges that limit their application\nin practice and industry. It is also the intention of this review to encourage\ncross-disciplinary collaborations for the development of more advanced\nscreening methodologies. For this specific reason, we undertake an additional\ntask of compiling and introducing all the elements that are needed for the\ndevelopment and operation of the performance-based screening workflows,\nincluding information about available materials databases, state-of-the-art\nmolecular simulation and process modelling tools and methods, and the full list\nof data and parameters required for each stage."
    },
    {
        "anchor": "Tensile deformation and fracture mechanisms of Cu/Nb nanolaminates\n  studied by in situ TEM mechanical tests: The mechanisms of deformation and failure of Cu/Nb nanolaminates manufactured\nby accumulated roll bonding were analysed using in-situ TEM mechanical tests.\nDog-bone small-scale tensile specimens were prepared using a FIB-based\ntechnique with the layers parallel and perpendicular to the loading axis. Load,\ndeformation and TEM micrographs were recorded during the in-situ TEM mechanical\ntests. The specimens deformed parallel to the layers presented very high strain\nhardening and ductility while those deformed in the perpendicular orientation\nwere more brittle. These results were rationalized in terms of the deformation\nand fracture mechanisms observed during the tests.",
        "positive": "Thickness dependent magnetotransport in ultra-thin manganite films: To understand the near-interface magnetism in manganites, uniform, ultra-thin\nfilms of La_{0.67}Sr_{0.33}MnO_3 were grown epitaxially on single crystal (001)\nLaAlO_3 and (110) NdGaO_3 substrates. The temperature and magnetic field\ndependent film resistance is used to probe the film's structural and magnetic\nproperties. A surface and/or interface related dead-layer is inferred from the\nthickness dependent resistance and magnetoresistance. The total thickness of\nthe dead layer is estimated to be $\\sim 30 \\AA$ for films on NdGaO_3 and $\\sim\n50 \\AA$ for films on LaAlO_3."
    },
    {
        "anchor": "Assessment of the GLLB-SC potential for solid-state properties and\n  attempts for improvement: Based on the work of Gritsenko et al. (GLLB) [Phys. Rev. A 51, 1944 (1995)],\nthe method of Kuisma et al. [Phys. Rev. B 82, 115106 (2010)] to calculate the\nband gap in solids was shown to be much more accurate than the common local\ndensity approximation (LDA) and generalized gradient approximation (GGA). The\nmain feature of the GLLB-SC potential (SC stands for solid and correlation) is\nto lead to a nonzero derivative discontinuity that can be conveniently\ncalculated and then added to the Kohn-Sham band gap for a comparison with the\nexperimental band gap. In this work, a thorough comparison of GLLB-SC with\nother methods, e.g., the modified Becke-Johnson (mBJ) potential [F. Tran and P.\nBlaha, Phys. Rev. Lett. 102, 226401 (2009)], for electronic, magnetic, and\ndensity-related properties is presented. It is shown that for the band gap,\nGLLB-SC does not perform as well as mBJ for systems with a small band gap and\nstrongly correlated systems, but is on average of similar accuracy as hybrid\nfunctionals. The results on itinerant metals indicate that GLLB-SC\noverestimates significantly the magnetic moment (much more than mBJ does), but\nleads to excellent results for the electric field gradient, for which mBJ is in\ngeneral not recommended. In the aim of improving the results, variants of the\nGLLB-SC potential are also tested.",
        "positive": "Tuning the catalytic activity of graphene nanosheets for oxygen\n  reduction reaction via size and thickness reduction: Currently, the fundamental factors that control the oxygen reduction reaction\n(ORR) activity of graphene itself, in particular the dependence of the ORR\nactivity on the number of exposed edge sites remain elusive, mainly due to\nlimited synthesis routes of achieving small size graphene. In this work, the\nsynthesis of low oxygen content (< 2.5 +/-0.2 at %), few layer graphene\nnanosheets with lateral dimensions smaller than a few hundred nm was achieved\nusing a combination of ionic liquid assisted grinding of high purity graphite\ncoupled with sequential centrifugation. We show for the first time, that the\ngraphene nanosheets possessing a plethora of edges exhibited considerably\nhigher electron transfer numbers compared to the thicker graphene\nnanoplatelets. This enhanced ORR activity was accomplished by successfully\nexploiting the plethora of edges of the nanosized graphene as well as the\nefficient electron communication between the active edge sites and the\nelectrode substrate. The graphene nanosheets were characterized by an onset\npotential of -0.13 V vs. Ag/AgCl and a current density of -3.85 mA/cm2 at -1 V,\nwhich represent the best ORR performance ever achieved from an undoped carbon\nbased catalyst. This work demonstrates how low oxygen content nanosized\ngraphene synthesized by a simple route can considerably impact the ORR\ncatalytic activity and hence it is of significance in designing and optimizing\nadvanced metal-free ORR electrocatalysts."
    },
    {
        "anchor": "Calculated iron $L_{2,3}$ x-ray absorption and XMCD of spin-crossover\n  Fe(phen)$_{2}$(NCS)$_{2}$ molecule adsorbed on Cu(001) surface: The PAW method has been used to compute the iron L$_{2,3}$ edges of x-ray\nabsorption spectra (XAS) and x-ray magnetic circular dichroism (XMCD) of the\nspin-crossover Fe(phen)$_{2}$(NCS)$_{2}$ molecule when adsorbed on Cu(001)\nsurface and in the gas phase, for both the high spin (HS) and low spin (LS)\nstates. It is found that the calculated XAS and XMCD with the static core hole\nor the Slater transition state half hole are in less good agreement with\nexperiment than those using the so called initial state. This disagreement is\ndue to the reduction of the iron spin magnetic moment caused by the static\nscreening of the core hole by the photo-electron. The L$_{2,3}$ XAS formula is\nfound to be directly related to the unoccupied $3d$ density of states (DOS),\nand hence the symmetry broken $e_g$ and the $t_{2g}$ iron DOS are used to\nexplain the XAS and XMCD results. It is demonstrated that the dependence of the\nHS XMCD on the direction of incident x-ray circularly polarized light with\nrespect to the magnetization direction can be used to determine the iron\noctahedron deformation, while the XMCD for various magnetization directions is\ndirectly related to the anisotropy of the orbital magnetic moment and the\nmagneto-crystalline energy. It is also shown that the magnetic dipole moment\n$T_z$ is very large due to the strong distortion of the iron octahedron and is\nnecessary for an accurate determination of the sum rule computed spin magnetic\nmoment.",
        "positive": "Pore and Ligament Size Control, Thermal Stability and Mechanical\n  Properties of Nanoporous Single Crystals of Gold: Nanoporous gold is widely used in research and nanotechnology because of its\ndiverse properties, including high surface area and catalytic activity. The\nligament size is usually considered as the only parameter controlling thermal\nstability and mechanical properties of nanoporous gold. Recently we developed a\nmethod for creating nanoporous single crystal gold particles using eutectic\ndecomposition of Au-Ge, followed by selective etching of Ge. Here, we used this\nnovel method to create nanoporous gold particles with controlled ligament sizes\nby changing the initial sample relative concentrations of gold and germanium.\nWhen investigated from 1 to 4 hour at 250 to 400 degrees C the material was\nthermally stable up to 350 degrees C, which is higher than the thermal\nstability of classical nanoporous gold with similar ligament sizes prepared by\ndealloying. Mechanical properties were examined utilizing nanoindentation of\nnanoporous gold before and after annealing. For smaller ligament sizes,\nhardness increases with annealing temperature up to 300 degrees C and then\nstrongly decreases. For larger ligament sizes, hardness decreases with\nincreasing annealing temperature. Young modulus was unchanged up to 300 degrees\nC."
    },
    {
        "anchor": "Complementary electrochemical ICP-MS flow cell and in-situ AFM study of\n  the anodic desorption of molecular adhesion promotors: Molecular adhesion promoters are a central component of modern coating\nsystems for the corrosion protection of structural materials. They are\ninterface active and form ultrathin corrosion inhibiting and adhesion-promoting\nlayers. Here we utilize thiol-based self-assembled monolayers (SAMs) as model\nsystem for demonstrating a comprehensive combinatorial approach to understand\nmolecular level corrosion protection mechanisms under anodic polarization.\nSpecifically, we compare hydrophilic 11-Mercapto-1-undecanol and hydrophobic\n1-Undecanethiol SAMs and their gold-dissolution inhibiting properties. We can\nshow that the intermolecular forces (hydrophobic vs hydrophilic effects)\ncontrol how SAM layers perform under oxidative conditions. Specifically, using\n\\textit{in situ} electrochemical AFM and a scanning-flow cell coupled to an\nICP-MS a complementary view on both corrosion resistance, as well as on changes\nin surface morphology/adhesion of the SAM is possible. Protection from\noxidative dissolution is higher with hydrophobic SAMs, which detach under\nmicelle formation, while the hydrophilic SAM exhibits lower protective effects\non gold dissolution rates, although it stays intact as highly mobile layer\nunder anodic polarization. The developed multi-technique approach will prove\nuseful for studying the interfacial activity and corrosion suppression\nmechanism of inhibiting molecules on other metals and alloys.",
        "positive": "Computational Amperometry of Nanoscale Capacitors in Molecular\n  Simulations: In recent years, constant applied potential molecular dynamics has allowed to\nstudy the structure and dynamics of the electrochemical double-layer of a large\nvariety of nanoscale capacitors. Nevertheless it remained impossible to\nsimulate polarized electrodes at fixed total charge. Here we show that\ncombining a constant potential electrode with a finite electric displacement\nfills this gap by allowing to simulate open circuit conditions. The method can\nbe extended by applying an electric displacement ramp to perform computational\namperometry experiments at different current intensities. As in experiments,\nthe full capacitance of the system is obtained at low intensity, but this\nquantity decreases when the applied ramp becomes too fast with respect to the\nmicroscopic dynamics of the liquid."
    },
    {
        "anchor": "Effect of boron and phosphorus codoping on the electronic and optical\n  properties of graphitic carbon nitride monolayers: First-principle\n  simulations: We study the effect of boron (B) and Phosphorous (P) co-doping on electronic\nand optical properties of graphitic carbon nitride (g-C$_3$N$_4$ or GCN)\nmonolayer using density functional simulations. The energy band structure\nindicates that the incorporation of B and P into a hexagonal lattice of GCN\nreduces the energy band gap from $3.1$ for pristine GCN to $1.9$ eV, thus\nextending light absorption toward the visible region. Moreover, on the basis of\ncalculating absorption spectra and dielectric function, the co-doped system\nexhibits an improved absorption intensity in the visible region and more\nelectronic transitions, which named $\\pi^*$ electronic transitions that\noccurred and were prohibited in the pristine GCN. These transitions can be\nattributed to charge redistribution upon doping, caused by distorted\nconfigurable B/P co-doped GCN confirmed by both electron density and Mulliken\ncharge population. Therefore, B/P co-doped GCN is expected to be an auspicious\ncandidate to be used as a promising photoelectrode in Photoelectrochemical\nwater splitting reactions leading to efficient solar H$_2$ production.",
        "positive": "Surface-Assisted Luminescence: the PL Yellow Band and the EL of n-GaN\n  Devices: Although everybody should know that measurements are never performed directly\non materials but on devices, this is not generally true. Devices are physical\nsystems able to exchange energy and thus subject to the laws of physics, which\ndetermine the information they provide. Hence, we should not overlook device\neffects in measurements as we do by assuming naively that photoluminescence\n(PL) is bulk emission free from surface effects. By replacing this unjustified\nassumption with a proper model for GaN surface devices, their yellow band PL\nbecomes surface-assisted luminescence that allows for the prediction of the\nweak electroluminescence recently observed in n-GaN devices when holes are\nbrought to their surfaces."
    },
    {
        "anchor": "Charge transfer induced interfacial ferromagnetism in\n  La$_{0.7}$Sr$_{0.3}$MnO$_3$/NdNiO$_3$: Charge transfer induced interfacial ferromagnetism and its impact on the\nexchange bias effect in La$_{0.7}$Sr$_{0.3}$MnO$_3$/NdNiO$_3$ correlated oxide\nheterostructures were investigated by soft x-ray absorption and x-ray magnetic\ncircular dichroism spectra in a temperature range from 10 to 300 K. Besides the\nantiferromagnetic Ni$_3^+$ cations which are naturally part of the NdNiO$_3$\nlayer, Ni$_2^+$ ions are formed at the interface due to a charge transfer\nmechanism involving the Mn element of the adjacent layer. They exhibit a\nferromagnetic behavior due to the exchange coupling to the Mn$_4^+$ ions in the\nLa$_{0.7}$Sr$_{0.3}$MnO$_3$ layer. This can be seen as detrimental to the\nstrength of the unidirectional anisotropy since a significant part of the\ninterface does not contribute to the pinning of the ferromagnetic layer. By\nanalyzing the line shape changes of the x-ray absorption at the Ni L$_{2,3}$\nedges, the metal-insulator transition of the NdNiO$_3$ layer is resolved in an\nelement specific manner. This phase transition is initiated at about 120 K, way\nabove the paramagnetic to antiferromagnetic transition of NdNiO$_3$ layer which\nmeasured to be 50 K. Exchange bias and enhanced coercive fields were observed\nafter field cooling the sample through the Neel temperature of the NdNiO$_3$\nlayer. Different from La$_{0.7}$Sr$_{0.3}$MnO$_3$/LaNiO$_3$, the exchange bias\nobserved in La$_{0.7}$Sr$_{0.3}$MnO$_3$/NdNiO$_3$ is due to the\nantiferromagnetism of NdNiO$_3$ and the frustration at the interface. These\nresults suggest that reducing the interfacial orbital hybridization may be used\nas a tunable parameter for the strength of the exchange bias effect in\nall-oxide heterostructures which exhibit a charge transfer mechanism.",
        "positive": "First-principles Calculation of the Formation Energy in MgO-CaO Solid\n  Solutions: The electronic structure and total energy were calculated for ordered and\ndisordered MgO-CaO solid solutions within the multiple scattering theory in\nreal space and the local density approximation. Based on the dependence of the\ntotal energy on the unit cell volume the equilibrium lattice parameter and\nformation energy were determined for different solution compositions. The\nformation energy of the solid solutions is found to be positive that is in\nagreement with the experimental phase diagram, which shows a miscibility gap."
    },
    {
        "anchor": "Ultrafast Optomagnonics in Ferrimagnetic Multi-Sublattice Garnets: This review discusses the ultrafast magnetization dynamics within the\ngigahertz to terahertz frequency range in ferrimagnetic rare-earth iron garnets\nwith different substitutions. In these garnets, the roles of spin-orbit and\nexchange interactions have been detected using femtosecond laser pulses via the\ninverse Faraday effect. The all-optical control of spin-wave and Kaplan-Kittel\nexchange resonance modes in different frequency ranges is shown. Generation and\nlocalization of the electric field distribution inside the garnet through the\nmetal-bound surface plasmon-polariton strongly enhance the amplitude of the\nexchange resonance modes. The exchange resonance mode in yttrium iron garnets\nwas observed using circularly polarized Raman spectroscopy. The results of this\nstudy may be utilized in the development of a wide class of optomagnonic\ndevices in the gigahertz to terahertz frequency range.",
        "positive": "Cooperative Multiscale Aging in a Ferromagnet/Antiferromagnet Bilayer: We utilize anisotropic magnetoresistance to study temporal evolution of the\nmagnetization state in epitaxial Ni$_{80}$Fe$_{20}$/Fe$_{50}$Mn$_{50}$\nferromagnet/antiferromagnet bilayers. The resistance exhibits power-law\nevolution over a wide range of temperatures and magnetic fields, indicating\nthat aging is characterized by a wide range of activation time scales. We show\nthat aging is a cooperative process, i.e. the magnetic system is not a\nsuperposition of weakly interacting subsystems characterized by simple\nArrhenius activation. The observed effects are reminiscent of avalanches in\ngranular materials, providing a conceptual link to a broad class of critical\nphenomena in other complex condensed matter systems."
    },
    {
        "anchor": "Ising Dynamics with Damping: We show for the Ising model that is possible construct a discrete time\nstochastic model analogous to the Langevin equation that incorporates an\narbitrary amount of damping. It is shown to give the correct equilibrium\nstatistics and is then used to investigate nonequilibrium phenomena, in\nparticular, magnetic avalanches. The value of damping can greatly alter the\nshape of hysteresis loops, and for small damping and high disorder, the\nmorphology of large avalanches can be drastically effected. Small damping also\nalters the size distribution of avalanches at criticality.",
        "positive": "Mechanical Deformation of Nanoscale Metal Rods: When size and shape\n  matters: Understanding nanomechanical response of materials represents a scientific\nchallenge. Here, we have used in-situ electron microscopy to reveal drastic for\nthe first time changes of structural behavior during deformation of 1-nm-wide\nmetal rods as a function of temperature. At 300 K, stretched nanowires stay\ndefect-free, while at 150 K, elongation is associated with planar defects. As\nsize is reduced, energy barriers become so small that ambient thermal energy is\nsufficient to overcome them. Nanorods display an elastic regime until a\nmechanism with high enough blocking barrier can be nucleated. Ab-initio\ncalculations revealed that contribution from surface steps overrule stacking\nfault energetics in nanorods, in such a way that system size and shape\ndetermines preferred fault gliding directions. This induces anisotropic\nbehavior and, even large differences in elastic or plastic response for\nelongation or compression. These results provide a new framework to improve\ntheoretical models and atomic potentials to describe the mechanical properties\nat nanoscale."
    },
    {
        "anchor": "Influence of the Fermi surface shape on magnetotransport: the MnAs case: We analyze the influence of the Fermi surface (FS) shape on magnetotransport\nproperties, particularly on the Hall effect in the MnAs compound. It has been\nobserved in MnAs films evidence of opposite conduction polarities for different\ncrystal direction (goniopolarity) and a strong dependence of the carrier type\nwith applied magnetic field. In order to understand this behaviour, we\ndeveloped a model based on the semiclassical equations along with Boltzmann\ntransport theory that takes into account both, the applied magnetic field and\nthe FS shape. The FS of the MnAs compound is obtained by means of density\nfunctional theory (DFT), showing a clear dominance of the hyperboloid shape.\nOur study, corroborate that this specific topology of the FS gives rise to a\ngoniopolar behaviour in the Hall transport. This theoretical results are\nsupported by magnetotransport measurements on MnAs thin layers epitaxially\ngrown on GaAs(001) and GaAs(111), where both configurations allow us to explore\nthe transport characteristics for two different crystal directions of the MnAs.",
        "positive": "Reentrant Adhesion Behavior in Nanocluster Deposition: We simulate the collision of atomic clusters with a weakly attractive surface\nusing molecular dynamics in a regime between soft-landing and fragmentation,\nwhere the cluster undergoes large deformation but remains intact. As a function\nof incident kinetic energy, we find a transition from adhesion to reflection at\nlow kinetic energies. We also identify a second adhesive regime at intermediate\nkinetic energies, where strong deformation of the cluster leads to an increase\nin contact area and adhesive energy."
    },
    {
        "anchor": "Nature of native atomic defects in ZrTe$_5$ and their impact on the\n  low-energy electronic structure: Over the past decades, investigations of the anomalous low-energy electronic\nproperties of ZrTe$_5$ have reached a wide array of conclusions. An open\nquestion is the growth method's impact on the stoichiometry of ZrTe$_5$\nsamples, especially given the very small density of states near its chemical\npotential. Here we report on high resolution scanning tunneling microscopy and\nspectroscopy measurements performed on samples grown via different methods.\nUsing density functional theory calculations, we identify the most prevalent\ntypes of atomic defects on the surface of ZrTe$_5$, namely Te vacancies and\nintercalated Zr atoms. Finally, we precisely quantify their density and outline\ntheir role as ionized defects in the anomalous resistivity of this material.",
        "positive": "Spin-group symmetry in magnetic materials with negligible spin-orbit\n  coupling: Symmetry formulated by group theory plays an essential role with respect to\nthe laws of nature, from fundamental particles to condensed matter systems.\nHere, by combining symmetry analysis and tight-binding model calculations, we\nelucidate that the crystallographic symmetries of a vast number of magnetic\nmaterials with light elements, in which the neglect of relativistic spin-orbit\ncoupling (SOC) is an appropriate approximation, are considerably larger than\nthe conventional magnetic groups. Thus, a symmetry description that involves\npartially-decoupled spin and spatial rotations, dubbed as spin group, is\nrequired. Spin group permits more symmetry operations and thus more energy\ndegeneracies that are disallowed by the magnetic groups. One consequence of the\nspin group is the new anti-unitary symmetries that protect SOC-free Z_2\ntopological phases with unprecedented surface node structures. Our work not\nonly manifests the physical reality of materials with weak SOC, but also shed\nlight on the understanding of all solids with and without SOC by a unified\ngroup theory."
    },
    {
        "anchor": "AFLOW for alloys: Many different types of phases can form within alloys, from highly-ordered\nintermetallic compounds, to structurally-ordered but chemically-disordered\nsolid solutions, and structurally-disordered (i.e. amorphous) metallic glasses.\nThe different types of phases display very different properties, so predicting\nphase formation is important for understanding how materials will behave. Here,\nwe review how first-principles data from the AFLOW repository and the aflow++\nsoftware can be used to predict phase formation in alloys, and describe some\ngeneral trends that can be deduced from the data, particularly with respect to\nthe importance of disorder and entropy in multicomponent systems.",
        "positive": "An Ice Structuring Mechanism for Zirconium Acetate: The control of ice nucleation and growth is critical in many natural and\nengineering situations. Yet, very few compounds are able to interact directly\nwith the surface of ice crystals. Ice-structuring proteins, found in certain\nfishes, plants and insects, bind to the surface of ice, thereby controlling\ntheir growth. We recently revealed the ice-structuring properties of zirconium\nacetate which are similar to those of ice-structuring proteins. Being a salt,\nand therefore different from the proteins having ice-structuring properties,\nits ice-structuring mechanism remains unelucidated. Here we investigate this\nice-structuring mechanism through the role of the concentration of zirconium\nacetate and of the ice crystal growth velocity. We then explore other compounds\npresenting similar functional groups (acetate, hydroxyl, or carboxylic groups).\nBased on these results, we propose that zirconium acetate adopts a\nhydroxy-bridged polymer structure which can bind to the surface of the ice\ncrystals through hydrogen bonding, thereby slowing down ice crystal growth."
    },
    {
        "anchor": "Generation of microwave radiation in planar spin-transfer devices: Current induced precession states in spin-transfer devices are studied in the\ncase of large easy plane anisotropy (present in most experimental setups). It\nis shown that the effective one-dimensional planar description provides a\nsimple qualitative understanding of the emergence and evolution of such states.\nSwitching boundaries are found analytically for the collinear device and the\nspin-flip transistor. The latter can generate microwave oscillations at zero\nexternal magnetic field without either special functional form of spin-transfer\ntorque, or ``field-like'' terms, if Gilbert constant corresponds to the\noverdamped planar regime.",
        "positive": "Simulations of the Static Friction Due to Adsorbed Molecules: The static friction between crystalline surfaces separated by a molecularly\nthin layer of adsorbed molecules is calculated using molecular dynamics\nsimulations. These molecules naturally lead to a finite static friction that is\nconsistent with macroscopic friction laws. Crystalline alignment, sliding\ndirection, and the number of adsorbed molecules are not controlled in most\nexperiments and are shown to have little effect on the friction. Temperature,\nmolecular geometry and interaction potentials can have larger effects on\nfriction. The observed trends in friction can be understood in terms of a\nsimple hard sphere model."
    },
    {
        "anchor": "Pulsed ESR Measurement of Coherence Times in Si:P at Very Low\n  Temperatures: A purpose built millikelvin pulsed x-band ESR system is used to measure spin\ndecoherence times of phosphorus donor spins in 99.92% isotopically pure 28\nsilicon. The isolated P spin T2 is estimated at 260 (50) ms at 4.2 K and 330\n(100) ms at 0.9 K.",
        "positive": "Van der Waals Coefficients of Atoms and Molecules from a Simple\n  Approximation for the Polarizability: A simple and computationally efficient scheme to calculate approximate\nimaginary-frequency dependent polarizability, hence asymptotic van der Waals\ncoefficient, within density functional theory is proposed. The dynamical\ndipolar polarizabilities of atoms and molecules are calculated starting from\nthe Thomas-Fermi-von Weizs\\\"acker (TFvW) approximation for the\nindependent-electron kinetic energy functional. The van der Waals coefficients\nfor a number of closed-shell ions and a few molecules are hence calculated and\ncompared with available values obtained by fully first-principles calculations.\nThe success in these test cases shows the potential of the proposed TFvW\napproximate response function in capturing the essence of long range\ncorrelations and may give useful information for constructing a functional\nwhich naturally includes van der Waals interactions."
    },
    {
        "anchor": "Emerging interfacial magnetization in isovalent manganite\n  heterostructures driven by octahedral coupling: The distortion of corner-sharing octahedra in isovalent perovskite\ntransition-metal oxide interfaces is proven to be an excellent way to tailor\nthe electronic and magnetic properties of their heterostructures. Combining\ndepth-dependent magnetic characterization technique; (polarized neutron\nreflectivity, PNR); and theoretical calculation (density functional theory), we\nreport interface-driven magnetic exchange interactions due to a modification in\nthe octahedral rotations at the interfaces in an isovalent La0.67Ca0.33MnO3\n(LCMO)/La0.67Sr0.33MnO3 (LSMO) heterostructures. PNR results determined a\nlength scale of ~ 8 unit cells at the interface, which demonstrated a\nmodification in magnetic properties. The results also predicted a\nlow-temperature exchange bias for these ferromagnetic heterostructures with a\nmaximum exchange bias for the heterostructure, which showed an enhanced\nantiferromagnetic coupling at the interfaces.",
        "positive": "Effects of hole self-trapping by polarons on transport and negative bias\n  illumination stress in amorphous-IGZO: The effects of hole injection in amorphous-IGZO is analyzed by means of\nfirst-principles calculations. The injection of holes in the valence band tail\nstates leads to their capture as a polaron, with high self-trapping energies\n(from 0.44 to 1.15 eV). Once formed, they mediate the formation of peroxides\nand remain localized close to the hole injection source due to the presence of\na large diffusion energy barrier (of at least 0.6eV). Their diffusion mechanism\ncan be mediated by the presence of hydrogen. The capture of these holes is\ncorrelated with the low off-current observed for a-IGZO transistors, as well\nas, with the difficulty to obtain a p-type conductivity. The results further\nsupport the formation of peroxides as being the root cause of Negative bias\nillumination stress (NBIS). The strong self-trapping substantially reduces the\ninjection of holes from the contact and limits the creation of peroxides from a\ndirect hole injection. In presence of light, the concentration of holes\nsubstantially rises and mediates the creation of peroxides, responsible for\nNBIS."
    },
    {
        "anchor": "Mobility of dislocations in semiconductors: Atomic-scale calculations for the dynamics of the 90$^0$ partial glide\ndislocation in silicon are made using the effective-medium tight-binding\ntheory. Kink formation and migration energies for the reconstructed partial\ndislocation are compared with experimental results for the mobility of this\ndislocation. The results confirm the theory that the partial moves in the\ndissociated state via the formation of stable kinks. The correlation between\nglide activation energy and band gap in semiconducting systems is discussed.",
        "positive": "Uranium at High Pressure from First Principles: The equation of state, structural behavior and phase stability of\n{\\alpha}-uranium have been investigated up to 1.3 TPa using density functional\ntheory, adopting a simple description of electronic structure that neglects the\nspin-orbit coupling and strong electronic correlations. The comparison of the\nenthalpies of Cmcm (alpha-U), bcc, hcp, fcc, and bct predicts that the aplpha-U\nphase is stable up to a pressure of ~285 GPa, above which it transforms to a\nbct-U phase. The enthalpy differences between the bct and bcc phase decrease\nwith pressure, but bcc is energetically unfavorable at least up to 1.3 TPa, the\nupper pressure limit of this study. The enthalpies of the close-packed hcp and\nfcc phases are 0.7 eV and 1.0 eV higher than that of the stable bct-U phase at\na pressure of 1.3 TPa, supporting the wide stability field of the bcc phase.\nThe equation of state, the lattice parameters and the anisotropic compression\nparameters are in good agreement with experiment up 100 GPa and previous\ntheory. The elastic constants at the equilibrium volume of alpha-U confirm our\nbulk modulus. This suggests that our simplified description of electronic\nstructure of uranium captures the relevant physics and may be used to describe\nbonding and other light actinides that show itinerant electronic behavior\nespecially at high pressure."
    },
    {
        "anchor": "Pressure-induced stabilization of carbonic acid and other compounds in\n  the C-H-O system: The physicochemical behavior of elements and compounds is heavily altered by\nhigh pressure. The occurrence of pressure-induced reactions and phase\ntransitions can be revealed by crystal structure prediction approaches. In this\nwork, we explore the C-H-O phase diagram up to 400 GPa exploiting an\nevolutionary algorithm for crystal structure predictions along with ab initio\ncalculations. Besides uncovering new stable polymorphs of high-pressure\nelements and known molecules, we predicted the formation of new compounds. A\n2CH4:3H2 inclusion compound forms at low pressure and remains stable up to 215\nGPa. Carbonic acid (H2CO3), highly unstable at ambient conditions, was\npredicted to form exothermically at mild pressure (about 1 GPa). As pressure\nrises, it polymerizes and, above 300 GPa, reacts with water to form\northocarbonic acid (H4CO4). This unexpected high-pressure chemistry is\nrationalized by analyzing charge density and electron localization function\ndistributions, and implications for general chemistry and planetary science are\nalso discussed.",
        "positive": "Emergence of a noncollinear magnetic state in twisted bilayer CrI3: The emergence of two-dimensional (2D) magnetic crystals and moir\\'e\nengineering has opened the door for devising new magnetic ground states via\ncompeting interactions in moir\\'e superlattices. Although a suite of\ninteresting phenomena, including multi-flavor magnetic states, noncollinear\nmagnetic states, moir\\'e magnon bands and magnon networks, has been predicted,\nnontrivial magnetic ground states in twisted bilayer magnetic crystals have yet\nto be realized. Here, by utilizing the stacking-dependent interlayer exchange\ninteractions in CrI3, we demonstrate in small-twist-angle bilayer CrI3 a\nnoncollinear magnetic ground state. It consists of both antiferromagnetic (AF)\nand ferromagnetic (FM) domains and is a result of the competing interlayer AF\ncoupling in the monoclinic stacking regions of the moir\\'e superlattice and the\nenergy cost for forming AF-FM domain walls. Above the critical twist angle of ~\n3{\\deg}, the noncollinear state transitions abruptly to a collinear FM ground\nstate. We further show that the noncollinear magnetic state can be controlled\nby gating through the doping-dependent interlayer AF interaction. Our results\ndemonstrate the possibility of engineering moir\\'e magnetism in twisted bilayer\nmagnetic crystals, as well as gate-voltage-controllable high-density magnetic\nmemory storage."
    },
    {
        "anchor": "Thermally enhanced photoluminescence and temperature sensing properties\n  of Sc$_2$W$_3$O$_{12}$:Eu$^{3+}$ phosphors: Currently,lanthanide ions doped luminescence materials applying as optical\nthermometers have arose much concern. Basing on the different responses of two\nemissions to temperature, the fluorescence intensity ratio (FIR) technique can\nbe executed and further estimate the sensitivities to assess the optical\nthermometry performances. In this study, we introduce different doping\nconcentrations of Eu$^{3+}$ ions into negative expansion material\nSc$_2$W$_3$O$_{12}$:Eu$^{3+}$, accessing to the thermal enhanced luminescence\nfrom 373 to 548 K, and investigate the temperature sensing properties in\ndetail. All samples exhibit good thermally enhanced luminescence behavior. The\nemission intensity of Sc$_2$W$_3$O$_{12}$: 6 mol% Eu$^{3+}$ phosphors reaches\nat 147.81% of initial intensity at 473 K. As the Eu doping concentration\nincreases, the resistance of the samples to thermal quenching decreases. The\nFIR technique based on the transitions 5D0-7F1 (592 nm) and 5D0-7F2 (613 nm) of\nEu$^{3+}$ ions demonstrate a maximum relative temperature sensitivity of 3.063%\nK-1 at 298 K for Sc$_2$W$_3$O$_{12}$:Eu$^{3+}$: 6 mol% Eu$^{3+}$ phosphors. The\nsensitivity of sample decreases with the increase of Eu$^{3+}$ concentration.\nBenefiting from the thermal enhanced luminescence performance and good\ntemperature sensing properties, the Sc$_2$W$_3$O$_{12}$:Eu$^{3+}$: Eu$^{3+}$\nphosphors can be applies as optical thermometers.",
        "positive": "Phonon Hall effect with first-principles calculations: Phonon Hall effect (PHE) has attracted a lot of attention in recent years\nwith many theoretical and experimental explorations published. While\nexperiments work on complicated materials, theoretical studies are still\nhovering around the phenomenon-based models. Moreover, previous microscopic\ntheory was found unable to explain large thermal Hall conductivity obtained by\nexperiments in strontium titanate (STO). Therefore, as a first attempt to\nbridge this gap, we implement first-principles calculations to explore the PHE\nin real materials. Our work provides a new benchmark of the PHE in sodium\nchloride (NaCl) under a large external magnetic field. Moreover, we demonstrate\nour results in barium titanate (BTO), and discuss the results in STO in detail\nabout their deviation from experiments. As a possible future direction, we\nfurther propose that the inner electronic Berry curvature plays an important\nrole in the PHE in STO."
    },
    {
        "anchor": "Accelerated kinetic Monte Carlo algorithm for diffusion limited kinetics: If a stochastic system during some periods of its evolution can be divided\ninto non-interacting parts, the kinetics of each part can be simulated\nindependently. We show that this can be used in the development of efficient\nMonte Carlo algorithms. As an illustrative example the simulation of\nirreversible growth of extended one dimensional islands is considered. The new\napproach allowed to simulate the systems characterized by parameters superior\nto those used in previous simulations.",
        "positive": "Program LMTART for Electronic Structure Calculations: A computer program LMTART for electronic structure calculations using full\npotential linear muffin-tin orbital method is described"
    },
    {
        "anchor": "Thermal conductivity of rare-earth scandates in comparison to other\n  oxidic substrate crystals: High-temperature thermal properties of three neighboring rare-earth scandates\nDyScO$_3$, TbScO$_3$ and GdScO$_3$ were compared to\nLa$_{0.29}$Sr$_{0.71}$Al$_{0.65}$Ta$_{0.35}$O$_3$ (LSAT) and sapphire. To\ncalculate thermal conductivity, heat capacity and thermal diffusivity were\nmeasured by differential scanning calorimetry and laser flash technique,\nrespectively. DyScO$_3$ and TbScO$_3$ showed an untypical rise in the thermal\nconductivity above 900\\,K, while for GdScO$_3$, LSAT and sapphire the expected\ndecrease at elevated temperatures could be observed. These results lead to the\nproposal of a new type of heat transport by migrating ions.",
        "positive": "Highly tunable polarization-engineered two-dimensional electron gas in\n  $\u03b5$-AlGaO3 / $\u03b5$-Ga2O3 heterostructures: We report on the modeling of polarization-induced two-dimensional electron\ngas (2DEG) formation at ${\\epsilon}$-AlGaO3 / ${\\epsilon}$-Ga2O3\nheterointerface and the effect of spontaneous polarization (Psp) reversal on\n2DEG density in ${\\epsilon}$-Ga2O3 /${\\epsilon}$-AlGaO3 / ${\\epsilon}$-Ga2O3\ndouble heterostructures. Density-functional theory (DFT) is utilized to\ncalculate the material properties of ${\\epsilon}$-Ga2O3 and ${\\epsilon}$-AlGaO3\nalloys. Using Schrodinger-Poisson solver along with DFT calculated parameters,\nthe 2DEG density is calculated as a function of barrier type and thickness. By\noptimizing the layer thicknesses of\n${\\epsilon}$-Ga2O3/${\\epsilon}$-AlGaO3/${\\epsilon}$-Ga2O3 heterostructures,\ncharge contrast ratios exceeding 1600 are obtained. This computational study\nindicates the high potential for ${\\epsilon}$-Ga2O3-based heterostructure\ndevices for non-volatile memories and neuromorphic applications."
    },
    {
        "anchor": "Friedel oscillations responsible for stacking fault of adatoms: The case\n  of Mg(0001) and Be(0001): We perform a first-principles study of Mg adatom and adislands on the\nMg(0001) surface, and Be adatom on Be(0001), to obtain further insights into\nthe previously reported energetic preference of the fcc faulty stacking of Mg\nmonomers on Mg(0001). We first provide a viewpoint on how Friedel oscillations\ninfluence ionic relaxation on these surfaces. Our three-dimensional\ncharge-density analysis demonstrates that Friedel oscillations have maxima\nwhich are more spatially localized than what one-dimensional average density or\ntwo-dimensional cross sectional plots could possibly inform: The well-known\ncharge-density enhancement around the topmost surface layer of Mg(0001) is\nstrongly localized at its fcc hollow sites. The charge accumulation at this\nsite explains the energetically preferred stacking fault of the Mg monomer,\ndimer and trimer. Yet, larger islands prefer the normal hcp stacking.\nSurprisingly, the mechanism by which the fcc site becomes energetically more\nfavorable is not that of enhancing the surface-adatom bonds but rather those\nbetween surface atoms. To confirm our conclusions, we analyze the stacking of\nBe adatom on Be(0001) - a surface also largely influenced by Friedel\noscillations. We find, in fact, a much stronger effect: The charge enhancement\nat the fcc site is even larger and, consequently, the stacking-fault energy\nfavoring the fcc site is quite large, 44 meV.",
        "positive": "Photodiode Response in a CH$_3$NH$_3$PbI$_3$/CH$_3$NH$_3$SnI$_3$\n  Heterojunction: Since the discovery of its photovoltaic properties organometallic salt\nCH$_3$NH$_3$PbI$_3$ became the subject of vivid interest. The material exhibits\nhigh light conversion efficiency, it lases in red color, and it can serve as\nthe basis for light emitting diodes and photodetectors. Here we report another\nsurprising feature of this material family, the photo-tunability of the diode\nresponse of a heterojunction made of CH$_3$NH$_3$PbI$_3$ and its close\nrelative, CH$_3$NH$_3$SnI$_3$. In the dark state the device behaves as a diode,\nwith the Sn homologue acting as the \"p\" side. The junction is extremely\nsensitive to illumination. A complete reversal of the diode polarity, the first\nobservation of its kind, is seen when the junction is exposed to red laser\nlight of 25 mW/cm$^2$ or larger power density. This finding opens up the\npossibility for a novel class of opto-electronic devices."
    },
    {
        "anchor": "Simulations of the Chain Length Dependence of the Melting Mechanism in\n  Short-Chained n-alkane Monolayers on Graphite: The melting transition in solid monolayers of a series of short-chained\nn-alkanes, n-octane (n-C8H18), n-decane (n-C10H22), and n-dodecane (n-C12H26)\nphysisorbed onto the graphite basal plane are studied through use of molecular\ndynamics simulations. Utilizing previous experimental observations of the solid\nphase behavior of these monolayers, this study investigates the temperature\ndependence of the phases and phase transitions in these three monolayers during\nthe solid-fluid phase transition, and compares the observed melting behavior to\nprevious studies of hexane and butane monolayers. In particular, this study\nseems to indicate a greater dependence of the melting transition on the\nformation of gauche defects in the alkyl chains as the chain length is\nincreased. In light of the previously proposed footprint reduction mechanism\nand variations where the formation of gauche defects are energetically negated,\nsimulations seem to suggest that decane and dodecane monolayers are generally\nequally as dependent upon the formation of gauche defects for the melting\ntransition to take place, whereas octane monolayers seem to have less\ndependence, but follow a trend that is established in previous studies of\nmelting in butane and hexane monolayers. Also, the phase transition from a\nsolid herringbone phase into an orientationally ordered intermediate phase is\nfound to exhibit some differences as compared to a recent study of hexane\nmonolayers, which may be interpreted as originating from the greater influence\nof gauche defects. Comparison to experimental melting temperatures is provided\nwhere possible, and applications involving thin film manipulation and\nlubrication is discussed.",
        "positive": "Spin Dynamics of a Canted Antiferromagnet in a Magnetic Field: The spin dynamics of a canted antiferromagnet with a quadratic spin-wave\ndispersion near $\\vq =0$ is shown to possess a unique signature. When the\nanisotropy gap is negligible, the spin-wave stiffness $\\dsw (\\vq, B) =\n(\\omega_{\\vq}-B)/q^2$ depends on whether the limit of zero field or zero\nwavevector is taken first. Consequently, $\\dsw $ is a strong function of\nmagnetic field at a fixed wavevector. Even in the presence of a sizeable\nanisotropy gap, the field dependence of both $\\dsw $ and the gap energy\ndistinguishes a canted antiferromagnet from a phase-separated mixture\ncontaining both ferromagnetic and antiferromagnetic regions."
    },
    {
        "anchor": "Isotopic Effect and Temperature Dependent Intramolecular Excitation\n  Energy Transfer in a Model Donor-Acceptor Dyad: We consider here the non-adiabatic energy transfer dynamics for a model\nbi-chromophore system consisting of a perylenediimide unit linked to a\nladder-type poly-(para-phenylene) oligomer. Starting from a semi-empirical\nparameterization of a model electron/phonon Hamiltonian, we compute the\ngolden-rule rate for energy transfer from the LPPP5 donor to the PDI acceptor.\nOur results indicate that the non-adiabatic transfer is promoted by the\nout-of-plane wagging modes of the C-H bonds even though theses modes give\nlittle or no contribution to the Franck Condon factors in this system. We also\npredict a kinetic isotope effect of $k^{(H)}/k^{(D)} = 1.7 - 2.5$ depending\nupon the temperature.",
        "positive": "Nonlinear Optical Spectroscopy of Photonic Metamaterials: We have obtained spectra of second-harmonic generation, third harmonic\ngeneration, and four-wave mixing from a fishnet metamaterial around its\nmagnetic resonance. The resonant behaviors are distinctly different from those\nfor ordinary materials. They result from the fact that the resonance is\nplasmonic, and its enhancement appears through the local field in the\nnanostructure."
    },
    {
        "anchor": "A rational use of BCA code MARLOWE for ballistic effects of ion beam\n  irradiation in the ion mixing formalism: comparison to Molecular Dynamics: Understanding ballistic effects caused by ion beam irradiation, and linking\nthem with induced structure can be a key point for controlling and predicting\nthe microstructure of irradiated materials. For this purpose, we have\ninvestigated ballistic effects from an ion mixing formalism point of view. The\ndisplacement cascades in copper and AgCu alloy were obtained using binary\ncollision approximation (BCA) and molecular dynamics (MD) simulations. We\nemployed BCA-based code MARLOWE for its ability to simulate high energy\ndisplacement cascades. A first set of simulations was performed using both\nmethods on pure copper for energies ranging from 0.5 keV to 20 keV. The results\nof BCA and MD simulations are compared, evidencing rationally parametrized\nMARLOWE to be predictive. A second set of simulations was then carried out\nusing BCA only. Following experimental studies, AgCu alloy was subjected to 1\nMeV krypton ions. MARLOW simulations are found to be in good agreement with\nexperimental results.",
        "positive": "Ab Initio Study of Screw Dislocations in Mo and Ta: A new picture of\n  plasticity in bcc transition metals: We report the first ab initio density-functional study of <111> screw\ndislocations cores in the bcc transition metals Mo and Ta. Our results suggest\na new picture of bcc plasticity with symmetric and compact dislocation cores,\ncontrary to the presently accepted picture based on continuum and interatomic\npotentials. Core energy scales in this new picture are in much better agreement\nwith the Peierls energy barriers to dislocation motion suggested by\nexperiments."
    },
    {
        "anchor": "Ultrasound cavitation and exfoliation dynamics of 2D materials re-vealed\n  in operando by X-ray free electron laser megahertz imaging: Ultrasonic liquid phase exfoliation is a promising method for the production\nof two-dimensional (2D) layered materials. A large number of studies have been\nmade in investigating the underlying ultrasound exfoliation mechanisms.\nHowever, due to the experimental challenges for capturing the highly transient\nand dynamic phenomena in real-time at sub-microsecond time and micrometer\nlength scales simultaneously, most theories reported to date still remain\nelusive. Here, using the ultra-short X-ray Free Electron Laser pulses (~25ps)\nwith a unique pulse train structure, we applied MHz X-ray Microscopy and\nmachine-learning technique to reveal unambiguously the full cycles of the\nultrasound cavitation and graphite layer exfoliation dynamics with\nsub-microsecond and micrometer resolution. Cyclic fatigue shock wave impacts\nproduced by ultrasound cloud implosion were identified as the dominant\nmechanism to deflect and exfoliate graphite layers mechanically. For the\ngraphite flakes, exfoliation rate as high as ~5 angstroms per shock wave impact\nwas observed. For the HOPG graphite, the highest exfoliation rate was ~0.15\nangstroms per impact. These new findings are scientifically and technologically\nimportant for developing industrial upscaling strategies for ultrasonic\nexfoliation of 2D materials.",
        "positive": "Large spin Hall conductivity and excellent hydrogen evolution reaction\n  activity in unconventional PtTe1.75 monolayer: Two-dimensional (2D) materials have gained lots of attention due to the\npotential applications. In this work, we propose that based on first-principles\ncalculations, the (2$\\times$2) patterned PtTe$_2$ monolayer with kagome lattice\nformed by the well-ordered Te vacancy (PtTe$_{1.75}$) hosts large spin Hall\nconductivity (SHC) and excellent hydrogen evolution reaction (HER) activity.\nThe unconventional nature relies on the $A1@1b$ band representation (BR) of the\nhighest valence band without SOC. The large SHC comes from the Rashba\nspin-orbit coupling (SOC) in the noncentrosymmetric structure induced by the Te\nvacancy. Even though it has a metallic SOC band structure, the $\\mathbb Z_2$\ninvariant is well defined due to the existence of the direct band gap and is\ncomputed to be nontrivial. The calculated SHC is as large as 1.25$\\times 10^3\n\\frac{\\hbar}{e} (\\Omega~cm)^{-1}$ at the Fermi level ($E_F$). By tuning the\nchemical potential from $E_F-0.3$ to $E_F+0.3$ eV, it varies rapidly and\nmonotonically from $-1.2\\times 10^3$ to 3.1$\\times 10^3 \\frac{\\hbar}{e}\n(\\Omega~cm)^{-1}$. In addition, we also find the Te vacancy in the patterned\nmonolayer can induce excellent HER activity. Our results not only offer a new\nidea to search 2D materials with large SHC, i.e., by introducing\ninversion-symmetry breaking vacancies in large SOC systems, but also provide a\nfeasible system with tunable SHC (by applying gate voltage) and excellent HER\nactivity."
    },
    {
        "anchor": "Effect of Two-Dimensionality on Step Bunching Induced by the Drift of\n  Adatoms: We study the effect of two-dimensionality on step bunching induced by drift\nof adatoms. When anisotropy of the diffusion coefficient changes alternately on\nconsecutive terraces like a Si(001) vicinal face, bunching occurs with the\ndrift of adatoms. If the fluctuation of step bunches is neglected as in the\none-dimensional model, the bunching with step-down drift is faster than that\nwith step-up drift in contradiction with the experiment by Latyshev and\ncoworkers. In a two-dimensional model, the step bunches wander heavily with\nstep-up drift and recombination with neighboring bunches occur more frequently\nthan those with step-down drift and the bunching is accelerated. When the\ndifference of kinetic coefficients between two types of steps is taken into\naccount, the bunching with step-up drift can be faster than that with step-down\ndrift.",
        "positive": "Theory of Magnetic Anisotropy in III_{1-x}Mn_{x}V Ferromagnets: We present a theory of magnetic anisotropy in ${\\rm III}_{1-x}{\\rm\nMn}_{x}{\\rm V}$ diluted magnetic semiconductors with carrier-induced\nferromagnetism. The theory is based on four and six band envelope functions\nmodels for the valence band holes and a mean-field treatment of their exchange\ninteractions with ${\\rm Mn}^{++}$ ions. We find that easy-axis reorientations\ncan occur as a function of temperature, carrier density $p$, and strain. The\nmagnetic anisotropy in strain-free samples is predicted to have a $p^{5/3}$\nhole-density dependence at small $p$, a $p^{-1}$ dependence at large $p$, and\nremarkably large values at intermediate densities. An explicit expression,\nvalid at small $p$, is given for the uniaxial contribution to the magnetic\nanisotropy due to unrelaxed epitaxial growth lattice-matching strains. Results\nof our numerical simulations are in agreement with magnetic anisotropy\nmeasurements on samples with both compressive and tensile strains. We predict\nthat decreasing the hole density in current samples will lower the\nferromagnetic transition temperature, but will increase the magnetic anisotropy\nenergy and the coercivity."
    },
    {
        "anchor": "Quantum spin Hall insulators and quantum valley Hall insulators of\n  BiX/SbX (X = H, F, Cl, and Br) monolayers with a record bulk band gap: Large bulk band gap is critical for application of the quantum spin Hall\n(QSH) insulator or two dimensional (2D) topological insulator (TI) in\nspintronic device operating at room temperature (RT). Based on the\nfirst-principles calculations, here we predict a group of 2D topological\ninsulators BiX/SbX (X = H, F, Cl, and Br) monolayers with extraordinarily large\nbulk gaps from 0.32 to a record value of 1.08 eV. These giant-gaps are entirely\ndue to the result of strong spin-orbit interaction related to px and py\norbitals of Bi/Sb atoms around the two valley K and K' of honeycomb lattice,\nwhich is different significantly from the one consisted of pz orbital just like\nin graphene/silicene. The topological characteristic of BiX/SbX monolayers is\nconfirmed by the calculated nontrivial Z2 index and an explicit construction of\nthe low energy effective Hamiltonian in these systems. We show that the\nhoneycomb structures of BiX monolayers remain stable even at a temperature of\n600 K. These features make the giant-gap TIs BiX/SbX monolayers an ideal\nplatform to realize many exotic phenomena and fabricate new quantum devices\noperating at RT. Furthermore, biased BiX/SbX monolayers become a quantum valley\nHall insulator, showing valley-selective circular dichroism.",
        "positive": "Conductivity of the defectless Graphene: Conductivity of the defectless, perfect crystal graphene is found at the\nneutrality point at zero temperature and in the limit of large dielectric\nconstant of the substrate. The steady state of the graphene with weak current\nis assumed to be an ideal, rare plasma of particle and hole excitations\ngoverned by the Boltzmann kinetic equation."
    },
    {
        "anchor": "Redox-controlled epitaxy and magnetism of oxide heterointerfaces:\n  EuO/SrTiO$_3$: We demonstrate a novel route to prepare thin films of the ferromagnetic\ninsulator Europium monoxide. Key is a redox-controlled interface reaction\nbetween metallic Eu and the substrate SrTiO$_3$ as the supplier of oxygen. The\nprocess allows tuning the electronic, magnetic and structural properties of the\nEuO films. Furthermore, we apply this technique to various oxidic substrates\nand demonstrate the universality and limits of a redox-controlled EuO film\nsynthesis.",
        "positive": "Direct Observation of Dynamic Symmetry Breaking above Room Temperature\n  in Methylammonium Lead Iodide Perovskite: Lead halide perovskites such as methylammonium lead triiodide (MAPI) have\noutstanding optical and electronic properties for photovoltaic applications,\nyet a full understanding of how this solution processable material works so\nwell is currently missing. Previous research has revealed that MAPI possesses\nmultiple forms of static disorder regardless of preparation method, which is\nsurprising in light of its excellent performance. Using high energy resolution\ninelastic X-ray (HERIX) scattering, we measure phonon dispersions in MAPI and\nfind direct evidence for another form of disorder in single crystals: large\namplitude anharmonic zone-edge rotational instabilities of the PbI_6 octahedra\nthat persist to room temperature and above, left over from structural phase\ntransitions that take place tens to hundreds of degrees below. Phonon\ncalculations show that the orientations of the methylammonium couple strongly\nand cooperatively to these modes. The result is a non-centrosymmetric,\ninstantaneous local structure, which we observe in atomic pair distribution\nfunction (PDF) measurements. This local symmetry breaking is unobservable by\nBragg diffraction, but can explain key material properties such as the\nstructural phase sequence, ultra low thermal transport, and large minority\ncharge carrier lifetimes despite moderate carrier mobility."
    },
    {
        "anchor": "Experimental determination of phonon thermal conductivity and Lorenz\n  ratio of single crystal metals: Al, Cu and Zn: We use a magnetothermal resistance method to measure lattice thermal\nconductivity of pure single crystal metals over a wide range of temperatures.\nLarge transverse magnetic fields are applied to suppress electronic thermal\nconduction. The total thermal conductivity and the electrical conductivity are\nmeasured as functions of applied magnetic field. The lattice thermal\nconductivity is then extracted by extrapolating the thermal conductivity versus\nelectrical conductivity curve at zero electrical conductivity. We used this\nmethod to experimentally measure the lattice thermal conductivity and Lorenz\nnumber in single crystal Al (100), Cu (100) and Zn (001) in a temperature range\nof 5 to 60 K. Our results show that the measured phonon thermal conductivity\nversus temperature plot has a peak around one tenth of the Debye Temperature,\nand the Lorenz number is found to deviate from the Sommerfeld value in the\nintermediate temperature range.",
        "positive": "Epitaxial Graphene Intercalation: A Route to Graphene Modulation and\n  Unique 2D Materials: Intercalation of atomic species through epitaxial graphene layers began only\na few years following its initial report in 2004. The impact of intercalation\non the electronic properties of the graphene is well known; however, the\nintercalant itself can also exhibit intriguing properties not found in nature.\nThis suggests that a shift in the focus of epitaxial graphene intercalation\nstudies may lead to fruitful exploration of many new forms of traditionally 3D\nmaterials. In the following forward-looking review, we summarize the primary\ntechniques used to achieve and characterize EG intercalation, and introduce a\nnew, facile approach to readily achieve metal intercalation at the\ngraphene/silicon carbide interface. We show that simple thermal\nevaporation-based methods can effectively replace complicated synthesis\ntechniques to realize large-scale intercalation of non-refractory metals. We\nalso show that these methods can be extended to the formation of compound\nmaterials based on intercalation. Two-dimensional (2D) silver (2D-Ag) and\nlarge-scale 2D gallium nitride (2D-GaNx) are used to demonstrate these\napproaches."
    },
    {
        "anchor": "Configurational constraints on glass formation in the liquid calcium\n  aluminate system: We report new time-resolved synchrotron x-ray diffraction (SXRD) measurements\nto track structural transformations in calcium-aluminate (CaO)x(Al2O3)1-x\nliquids during glass formation, and review recent progress in neutron\ndiffraction with isotope substitution (NDIS) experiments, combined with\naspherical ion model molecular dynamics (AIM-MD) simulations, to identify the\natomic-scale configurational constraints on glass-forming ability.",
        "positive": "Accurate force-field methodology capturing atomic reconstructions in\n  transition metal dichalcogenide moir\u00e9 systems: In this work, a generalized force-field methodology for the relaxation of\nlarge moir\\'e heterostructures is proposed. The force-field parameters are\noptimized to accurately reproduce the structural degrees of freedom of some\ncomputationally manageable cells relaxed using density functional theory. The\nparameters can then be used to handle large moir\\'e systems. We specialize to\nthe case of 2H-phased twisted transition-metal dichalcogenide homo- and\nheterobilayers using a combination of the Stillinger-Weber intralayer- and the\nKolmogorov-Crespi interlayer-potential. Force-field parameters are developed\nfor all combinations of MX$_2$ for $\\text{M}\\in\\{\\text{Mo},\\text{W}\\}$ and\n$\\text{X}\\in\\{\\text{S},\\text{Se},\\text{Te}\\}$. The results show agreement\nwithin 20 meV in terms of band structure between density functional theory and\nforce-field relaxation. Using the relaxed structures, a simplified and\nsystematic scheme for the extraction of the interlayer moir\\'e potential is\npresented for both R- and H-stacked systems. We show that in-plane and\nout-of-plane relaxation effects on the moir\\'e potential, which is made both\ndeeper and wider after relaxation, are essential. An interpolation based\nmethodology for the calculation of the interlayer binding energy is also\nproposed. Finally, we show that atomic reconstruction, which is captured by the\nforce-field method, becomes especially prominent for angles below 4-5$^\\circ$,\nwhen there is no mismatch in lattice constant between layers."
    },
    {
        "anchor": "Short to Intermediate-range Structure , Transport , and Thermophysical\n  Properties of LiF-NaF-ZrF4 Molten Salts: LiF-NaF-ZrF4 multicomponent molten salts are identified as promising\ncandidates for coolant salts in molten salt reactors and advanced\nhigh-temperature reactors. Herein, ab-initio molecular dynamics (AIMD)\ncalculations were performed and compared with available experimental data to\nassess the ability of polarizable ion models (PIM) to reproduce short to\nintermediate-range structure, transport and thermophysical properties of the\nLiF-NaF-ZrF4 salt mixtures. This study signifies the importance of accurate\nsalt structure generation for accurate prediction of transport and\nthermophysical properties of multicomponent molten salts.\n  Keywords: Multicomponent Molten salts, Ab-initio molecular dynamics,\nPolarizable ion model, Fluorozirconate chains, Neoteric liquids simulation,\nIonic liquids, Thermophysical properties, Diffusion coefficients.",
        "positive": "Decoupled Strain Response of Ferroic Properties in Multiferroic VOCl2\n  Monolayer: Two-dimensional (2D) magnetoelectric multiferroics are promising\nmultifunctional materials for miniaturized logic and memory devices. Herein, we\nexplore the effectiveness of strain-engineering for tuning the properties of a\nrecently predicted 2D antiferromagnetic-ferroelectric, VOCl2 monolayer.\nInterestingly, we find that magnetic-ordering and electric polarization can be\ntuned independently using uniaxial tensile strain along different in-plane\nlattice vectors. A 4% tensile strain along lattice vector b induces a\ntransition from an antiferromagnetic (AFM) ground state with an out-of-plane\nmagnetization to a ferromagnetic (FM) ground state with in-plane magnetization.\nOn the other hand, tensile strain along lattice vector a enhances spontaneous\nelectric polarization, without affecting the magnetic ordering. The monolayers\nremain dynamically stable under tensile strain, which further helps to raise\nthe Curie temperature of ferromagnetism, as well as ferroelectricity. Such a\nstrain-tunable multiferroic material holds great promises for future generation\nnanoelectronic devices."
    },
    {
        "anchor": "About anomalous g-factor value of Mn related defects in GaAs:Mn: The results of experimental investigations of ESR spectra of manganese\nimpurity ions in a GaAs : Mn system are presented. The studies are done for\nvarious a Fermi level position relative to valence band edge in the system.\nCharacteristic defects for the system that give rise to lines with g factors of\n5.62 and 2.81 in the ESR spectra are studied in some detail. The experimental\nresults are discussed in the framework of a previously developed model with a\ndouble defect involving the impurity ion. The \"3d5 + hole\" model is a special\ncase of the double defect model in this system. An analytical expression for\nthe covalent renormalization of the g factor of an ESR line in this system is\nobtained.",
        "positive": "Role of Metal Centers in Tuning the Electronic Properties of\n  Graphene-Based Conductive Interfaces: A major bottleneck in the fabrication of efficient bio-organic nanoelectronic\ndevices resides in the strong charge recombination that is present at the\ndifferent interfaces forming the complex system. An efficient way to overcome\nthis bottleneck is to add a self-assembled monolayer (SAM) of molecules between\nthe biological material and the electrode that promotes an efficient direct\nelectron transfer whilst minimising wasteful processes of charge recombination.\nIn this work, the presence of a pyrene-nitrilotriacetic acid layer carrying\ndifferent metal centers as SAM physisorbed on graphene is fully described by\nmean of electrochemical analysis, field emission scanning electron microscopy,\nphotoelectrochemical characterisation and theoretical calculations. Our\nmultidisciplinary study reveals that the metal center holds the key role for\nthe efficient electron transfer at the interface. While Ni2+ is responsible for\nan electron transfer from SAM to graphene, Co2+ and Cu2+ force an opposite\ntransfer, from graphene to SAM. Moreover, since Cu2+ inhibits the electron\ntransfer due to a strong charge recombination, Co2+ seems the transition metal\nof choice for the efficient electron transfer."
    },
    {
        "anchor": "Spin-orbit torque-driven skyrmion dynamics revealed by time-resolved\n  X-ray microscopy: Magnetic skyrmions are topologically-protected spin textures with attractive\nproperties suitable for high-density and low-power spintronic device\napplications. Much effort has been dedicated to understanding the dynamical\nbehaviours of the magnetic skyrmions. However, experimental observation of the\nultrafast dynamics of this chiral magnetic texture in real space, which is the\nhallmark of its quasiparticle nature, has so far remained elusive. Here, we\nreport nanosecond-dynamics of a 100 nm-size magnetic skyrmion during a current\npulse application, using a time-resolved pump-probe soft X-ray imaging\ntechnique. We demonstrate that distinct dynamic excitation states of magnetic\nskyrmions, triggered by current-induced spin-orbit torques, can be reliably\ntuned by changing the magnitude of spin-orbit torques. Our findings show that\nthe dynamics of magnetic skyrmions can be controlled by the spin-orbit torque\non the nanosecond time scale, which points to exciting opportunities for\nultrafast and novel skyrmionic applications in the future.",
        "positive": "Selective Spin-State Switch and Metal-Insulator Transition in \\boldmath\n  $\\rm GdBaCo_2O_{5.5}$: Ultra-high resolution synchrotron diffraction data for $\\rm GdBaCo_2O_{5.5}$\nthrow new light on the metal-insulator transition of Co$^{3+}$ Ba-cobaltites.\nAn anomalous expansion of CoO$_6$ octahedra is observed at the phase transition\non heating, while CoO$_5$ pyramids show the normal shrinking at the closing of\nthe gap. The insulator-to-metal transition is attributed to a sudden excitation\nof some electrons in the octahedra ($t_{2g}^6$ state) into the Co $e_g$ band\n(final $t_{2g}^4e_g^2$ state). The $t_{2g}^5e_g^1$ state in the pyramids does\nnot change and the structural study also rules out a\n$d_{3x^2-r^2}/d_{3y^2-r^2}$ orbital ordering at $T_{MI}$."
    },
    {
        "anchor": "Current-Voltage Characteristics of Graphane p-n Junctions: In contrast to graphene which is a gapless semiconductor, graphane, the\nhydrogenated graphene, is a semiconductor with an energy gap. Together with the\ntwo-dimensional geometry, unique transport features of graphene, and\npossibility of doping graphane, p and n regions can be defined so that 2D p-n\njunctions become feasible with small reverse currents. This paper introduces a\nbasic analysis to obtain current-voltage characteristics of such a 2D p-n\njunction based on graphane. As we show, within the approximation of Shockley\nlaw of junctions, an ideal I-V charactristic for this p-n junction is to be\nexpected.",
        "positive": "The effect of low-energy ion-implantation on the electrical transport\n  properties of Si-SiO2 MOSFETs: Using silicon MOSFETs with thin (5nm) thermally grown SiO2 gate dielectrics,\nwe characterize the density of electrically active traps at low-temperature\nafter 16keV phosphorus ion-implantation through the oxide. We find that, after\nrapid thermal annealing at 1000oC for 5 seconds, each implanted P ion\ncontributes an additional 0.08 plus/minus 0.03 electrically active traps,\nwhilst no increase in the number of traps is seen for comparable silicon\nimplants. This result shows that the additional traps are ionized P donors, and\nnot damage due to the implantation process. We also find, using the room\ntemperature threshold voltage shift, that the electrical activation of donors\nat an implant density of 2x10^12 cm^-2 is ~100%."
    },
    {
        "anchor": "Thermal Stability and Electrical Control of Magnetization of\n  Heusler/Oxide Interface and Non-collinear Spin Transport of Its Junction: Towards next-generation spintronics devices, such as computer memories and\nlogic chips, it is necessary to satisfy high thermal stability, low-power\nconsumption and high spin-polarization simultaneously. Here, from\nfirst-principles, we investigate thermal stability (both structure and\nmagnetization) and the electric field control of magnetic anisotropy on Co2FeAl\n(CFA)/MgO. A phase diagram of structural thermal stability of the CFA/MgO\ninterface is illustrated. An interfacial perpendicular-anisotropy, coming from\nthe Fe-O orbital hybridization, provides high magnetic thermal stability and a\nlow stray field. We find an electric-field-induced giant modification of such\nperpendicular-anisotropy via a great magnetoelectric effect (the anisotropy\nenergy coefficient beta~10-7 erg/V cm). Our spin electronic-structure and\nnon-collinear transport calculations indicate high spin-polarized interfacial\nstates and good magnetoresistance properties of CFA/MgO/CFA perpendicular\nmagnetic tunnel junctions.",
        "positive": "Resonant photonic crystals based on van der Waals heterostructures: We propose to use 2D monolayers possessing optical gaps and high exciton\noscillator strength as an element of one-dimensional resonant photonic\ncrystals. We demonstrate that such systems are promising for the creation of\neffective and compact delay units. In the transition-metal-dichalcogenide-based\nstructures where the frequencies of Bragg and exciton resonances are close, a\npropagating short pulse can be slowed down by few picoseconds while the pulse\nintensity decreases only 2 - 5 times. This is realized at the frequency of the\n\"slow\" mode situated within the stopband. The pulse retardation and attenuation\ncan be controlled by detuning the Bragg frequency from the exciton resonance\nfrequency."
    },
    {
        "anchor": "Interlayer ferromagnetism and insulator-metal transition in\n  element-doped CrI3 thin films: The exploration of magnetism in two-dimensional layered materials has\nattracted extensive research interest. For the monoclinic phase CrI3 with\ninterlayer antiferromagnetism, finding a static and robust way of realizing the\nintrinsic interlayer ferromagnetic coupling is desirable. In this Letter, we\nstudy the electronic structure and magnetic properties of the nonmagnetic\nelement (e.g., O, S, Se, N, P, As and C) doped bi- and triple-layer CrI3\nsystems via first-principles calculations. Our results demonstrate that O, P,\nS, As, and Se doped CrI3 bilayer can realize interlayer ferromagnetism. Further\nanalysis shows that the interlayer ferromagnetic coupling in the doped\nfew-layer CrI3 is closely related to the formation of localized spin-polarized\nstate. This finding indicates that insulated interlayer ferromagnetism can be\nrealized at high doping concentration (larger than 8.33%). When the doping\nconcentration is less than 8.33%, but larger than 2.08%, an insulator-metal\nphase transition can occur since the localized spin-polarized states percolate\nto form contiguous grids in few-layer CrI3.",
        "positive": "Determining doping efficiency and mobility from conductivity and Seebeck\n  data of n-doped C60 layers: In this work, we introduce models for deriving lower limits for the key\nparameters doping efficiency, charge carrier concentration, and charge carrier\nmobility from conductivity data of doped organic semiconductors. The models are\napplied to data of thin layers of Fullerene C60 n-doped by four different\nn-dopants. Combining these findings with thermoelectric Seebeck data, the\nenergetic position of the transport level can be narrowed down and trends for\nthe absolute values are derived."
    },
    {
        "anchor": "Assessing the Reliability of Minimally Constrained Reverse Monte Carlo\n  Simulations for Model Metallic Liquids: Molecular dynamics simulations using semi-empirical potentials are examined\nfor three liquids to check the reliability of reverse Monte Carlo (RMC)\nsimulations to reproduce atomic configurations when only total pair correlation\nfunctions (TPCF) are used as constraints. The local structures are determined\nfrom a Voronoi tessellation of the ensemble and compared with the structures\nobtained by RMC in terms of asphericity, volume, coordination number, Voronoi\nindex, and nearest-neighbor distance. It is found that in general the\ndistributions generated from RMC do not match the MD configurations, using the\n$L^1$ (taxicab) distance as a metric, although in some cases a measure of\ncentral tendency for the distribution did match. Since only TPCFs are typically\nused to constrain the RMC simulations of experimental data, this study\nestablishes the limits on what can be learned by this analysis. It indicates\nthat caution should be used when interpreting RMC-generated structures using\nfew constraints since many structural quantities are not reproduced well.",
        "positive": "Anisotropic magnetocaloric effect in all-ferromagnetic\n  (La0.7Sr0.3MnO3/SrRuO3) superlattices: We exploit the magnetic interlayer coupling in La0.7Sr0.3MnO3/SrRuO3\nsuperlattices to realize a crossover between inverse and conventional magnetic\nentropy changes. Our data reveal a strong anisotropic nature of the\nmagnetocaloric effect due to the magnetic anisotropy of the superlattice.\nTherefore, artificial superlattices built from ferromagnetic materials that can\nbe used to alter the magnetic structure as well as the magnetic anisotropy,\ncould also be utilized for tuning the magnetocaloric properties, which may open\na constructive approach for magnetic refrigeration applications."
    },
    {
        "anchor": "Thermal treatment of superconductor thin film of the BSCCO system using\n  domestic microwave oven: In this work, we report the preparation of a superconductor thin film of the\nBSCCO system using a good quality powder with nominal composition\nBi_{1.8}Pb_{0.4}Sr_2CaCu_2O_x which was thermally treated using a domestic\nmicrowave oven (2.45 GHz, 800 W). This film was grew on a single crystal of\nLaAlO_3(100) substrate and exhibited a crystalline structure with the c-axis\nperpendicular to the plane of the substrate. An onset superconducting\ntransition temperature was measured at 80 K.",
        "positive": "Theory of Inelastic Electron Tunneling from a Localized Spin in the\n  Impulsive Approximation: A simple expression for the conductance steps in the inelastic electron\ntunneling from spin excitations in a single magnetic atom adsorbed on a\nnon-magnetic metal surfaces is derived. The inelastic coupling between the\ntunneling electron and the spin is via the exchange coupling and is treated in\nan impulsive approximation using the Tersoff-Hamann approximation for the\ntunneling between the tip and the sample. Our results for conductance steps\njustify the analysis carried out by Hirjebedin et al. [Science 317, 1199\n(2007)] of observed step-like conductances by inelastic electron tunneling from\nspin excitations in a single magnetic adatom using a simple spin matrix\nelement. In addition, our result gives a simple expression for the magnitudes\nof conductance steps and their lateral spatial variation with respect to the\ntip position, which can be calculated directly from spin-polarized wave\nfunctions at the Fermi level of the sample."
    },
    {
        "anchor": "Computationally Efficient Prediction of Area per Lipid: Area per lipid (APL) is an important property of biological and artificial\nmembranes. Newly constructed bilayers are characterized by their APL and newly\nelaborated force fields must reproduce APL. Computer simulations of APL are\nvery expensive due to slow conformational dynamics. The simulated dynamics\nincreases exponentially with respect to temperature. APL dependence on\ntemperature is linear over an entire temperature range. I provide numerical\nevidence that thermal expansion coefficient of a lipid bilayer can be computed\nat elevated temperatures and extrapolated to the temperature of interest. Thus,\nsampling times to predict accurate APL are reduced by a factor of ~10.",
        "positive": "Bilayer Vanadium Dioxide Thin Film with Elevated Transition Temperatures\n  and High Resistance Switching: Despite widespread interest in the phase-change applications of vanadium\ndioxide (VO$_2$), the fabrication of high-quality VO$_2$ thin films with\nelevated transition temperatures (TIMT) and high Insulator-Metal-Transition\nresistance switching still remains a challenge. This study introduces a\ntwo-step atmospheric oxidation approach to fabricate bilayer VO$_{2-x}$/VO$_2$\nfilms on a c-plane sapphire substrate. To quantify the impact of the VO$_2$\nbuffer layer, a single-layer VO$_2$ film of the same thickness was also\nfabricated. The bilayer VO$_{2-x}$/VO$_2$ films wherein the top VO$_{2-x}$ film\nwas under-oxidized demonstrated an elevation in TIMT reaching ~97 $^\\circ$C,\none of the highest reported to date for VO$_2$ films and is achieved in a\ndoping-free manner. Our results also reveal a one-order increase in resistance\nswitching, with the optimum bilayer VO$_2$/VO$_2$ film exhibiting ~3.6 orders\nof switching from 25 $^\\circ$C to 110 $^\\circ$C, compared to the optimum\nsingle-layer VO$_2$ reference film. This is accompanied by a one-order decrease\nin the on-state resistance in its metallic phase. The elevation in TIMT,\ncoupled with increased strain extracted from the XRD characterization of the\nbilayer film, suggests the possibility of compressive strain along the c-axis.\nThese VO$_{2-x}$/VO$_2$ films also demonstrate a significant change in the\nslope of their resistance vs temperature curves contrary to the conventional\nsmooth transition. This feature was ascribed to the rutile/monoclinic\nquasi-heterostructure formed due to the top VO$_{2-x}$ film having a reduced\nTIMT. Our findings carry significant implications for both the lucid\nfabrication of VO$_2$ thin film devices as well as the study of phase\ntransitions in correlated oxides."
    },
    {
        "anchor": "Superconductivity in Shear Strained Semiconductors: Semiconductivity and superconductivity are remarkable quantum phenomena that\nhave immense impact on science and technology, and materials that can be tuned,\nusually by pressure or doping, to host both types of quantum states are of\ngreat fundamental and practical significance. Here we show by first-principles\ncalculations a distinct route for tuning semiconductors into superconductors by\ndiverse large-range elastic shear strains, as demonstrated in exemplary cases\nof silicon and silicon carbide. Analysis of strain driven evolution of bonding\nstructure, electronic states, lattice vibration, and electron-phonon coupling\nunveils robust pervading deformation induced mechanisms auspicious for\nmodulating semiconducting and superconducting states under versatile material\nconditions. This finding opens vast untapped structural configurations for\nrational exploration of tunable emergence and transition of these intricate\nquantum phenomena in a broad range of materials.",
        "positive": "Layered Antiferromagnetism Induces Large Negative Magnetoresistance in\n  the van der Waals Semiconductor CrSBr: The recent discovery of magnetism within the family of exfoliatable van der\nWaals (vdW) compounds has attracted considerable interest in these materials\nfor both fundamental research and technological applications. However current\nvdW magnets are limited by their extreme sensitivity to air, low ordering\ntemperatures, and poor charge transport properties. Here we report the magnetic\nand electronic properties of CrSBr, an air-stable vdW antiferromagnetic\nsemiconductor that readily cleaves perpendicular to the stacking axis. Below\nits N\\'{e}el temperature, $T_N = 132 \\pm 1$ K, CrSBr adopts an A-type\nantiferromagnetic structure with each individual layer ferromagnetically\nordered internally and the layers coupled antiferromagnetically along the\nstacking direction. Scanning tunneling spectroscopy and photoluminescence (PL)\nreveal that the electronic gap is $\\Delta_E = 1.5 \\pm 0.2$ eV with a\ncorresponding PL peak centered at $1.25 \\pm 0.07$ eV. Using magnetotransport\nmeasurements, we demonstrate strong coupling between magnetic order and\ntransport properties in CrSBr, leading to a large negative magnetoresistance\nresponse that is unique amongst vdW materials. These findings establish CrSBr\nas a promising material platform for increasing the applicability of vdW\nmagnets to the field of spin-based electronics."
    },
    {
        "anchor": "A peeling approach for integrated manufacturing of large mono-layer h-BN\n  crystals: Hexagonal boron nitride (h-BN) is the only known material aside from graphite\nwith a structure composed of simple, stable, non-corrugated atomically thin\nlayers. While historically used as lubricant in powder form, h-BN layers have\nbecome particularly attractive as an ultimately thin insulator. Practically all\nemerging electronic and photonic device concepts rely on h-BN exfoliated from\nsmall bulk crystallites, which limits device dimensions and process\nscalability. Here, we address this integration challenge for mono-layer h-BN\nvia a chemical vapour deposition process that enables crystal sizes exceeding\n0.5 mm starting from commercial, reusable platinum foils, and in unison allows\na delamination process for easy and clean layer transfer. We demonstrate\nsequential pick-up for the assembly of graphene/h-BN heterostructures with\natomic layer precision, while minimizing interfacial contamination. Our process\ndevelopment builds on a systematic understanding of the underlying mechanisms.\nThe approach can be readily combined with other layered materials and opens a\nscalable route to h-BN layer integration and reliable 2D material device layer\nstacks.",
        "positive": "Kelvin modes of a skyrmion line in chiral magnets and the associated\n  magnon transport: Magnetic skyrmions in bulk crystals are line-like topologically protected\nspin textures. They allow for the propagation of magnons along the skyrmion\nline but are localized inside the skyrmion line. Analogous to the vortex line,\nthese propagating modes are the Kelvin modes of a skyrmion line. In crystals\nwithout an inversion center, it is known that the magnon dispersion in the\nferromagnetic state is asymmetric in the wavevector. It is natural to expect\nthat the dispersion of the Kelvin modes is also asymmetric with respect to the\nwavevector. We study the Kelvin modes of a skyrmion line in the ferromagnetic\nbackground. In contrast, we find that the lowest Kelvin mode is symmetric in\nthe wavevector in the low energy region despite the inversion symmetry\nbreaking. Other Kelvin modes below the magnon continuum are asymmetric, and\nmost of them have a positive group velocity. Our results suggest that a\nskyrmion line can function as a one-way waveguide for magnons."
    },
    {
        "anchor": "AC-frequency switchable correlated transports in rare-earth perovskite\n  nickelates: Whilst electron correlations were previously recognized to trigger beyond\nconventional direct current (DC) electronic transportations (e.g.\nmetal-to-insulator transitions, bad metal, thermistors), their respective\ninfluences to the alternation current (AC) transport are largely overlooked.\nHerein, we demonstrate active regulations in the electronic functionalities of\nd-band correlated rare-earth nickelate (ReNiO3) thin films, by simply utilizing\ntheir electronic responses to AC-frequencies (fAC). Assisted by temperature\ndependent near edge X-ray absorption fine structure analysis, we discovered\npositive temperature dependences in Coulomb viscosity of ReNiO3 that moderates\ntheir AC impedance. Distinguished crosslinking among R(Real)-fAC measured in\nnearby temperatures is observed that differs to conventional oxides. It enables\nactive adjustability in correlated transports of ReNiO3, among NTCR-, TDelta-\nand PTCR- thermistors, via fAC from the electronic perspective without varying\nmaterials or device structures. The TDelta-fAC relationship can be further\nwidely adjusted via Re composition and interfacial strains. The AC-frequency\nsensitivity discovered in ReNiO3 brings in a new freedom to regulating and\nswitching the device working states beyond the present semiconductor\ntechnologies. It opens a new paradigm for enriching novel electronic\napplications catering automatic transmission or artificial intelligence in\nsensing temperatures and frequencies.",
        "positive": "Annealing stability of magnetic tunnel junctions based on dual MgO free\n  layers and [Co/Ni] based thin synthetic antiferromagnet fixed system: We study the annealing stability of bottom-pinned perpendicularly magnetized\nmagnetic tunnel junctions based on dual MgO free layers and thin fixed systems\ncomprising a hard [Co/Ni] multilayer antiferromagnetically coupled to thin a Co\nreference layer and a FeCoB polarizing layer. Using conventional magnetometry\nand advanced broadband ferromagnetic resonance, we identify the properties of\neach sub-unit of the magnetic tunnel junction and demonstrate that this\nmaterial option can ensure a satisfactory resilience to the 400$^\\circ$C\nthermal annealing needed in solid-state magnetic memory applications. The dual\nMgO free layer possesses an anneal-robust 0.4 T effective anisotropy and\nsuffers only a minor increase of its Gilbert damping from 0.007 to 0.010 for\nthe toughest annealing conditions. Within the fixed system, the ferro-coupler\nand texture-breaking TaFeCoB layer keeps an interlayer exchange above 0.8\nmJ/m$^2$, while the Ru antiferrocoupler layer within the synthetic\nantiferromagnet maintains a coupling above -0.5 mJ/m$^2$. These two strong\ncouplings maintain the overall functionality of the tunnel junction upon the\ntoughest annealing despite the gradual degradation of the thin Co layer\nanisotropy that may reduce the operation margin in spin torque memory\napplications. Based on these findings, we propose further optimization routes\nfor the next generation magnetic tunnel junctions."
    },
    {
        "anchor": "Composition dependent electrochemical properties of earth-abundant\n  ternary nitride anodes: Growing energy storage demands on lithium-ion batteries necessitate\nexploration of new electrochemical materials as next-generation battery\nelectrode materials. In this work, we investigate the previously unexplored\nelectrochemical properties of earth-abundant and tunable Zn1-xSn1+xN2 (x = -0.4\nto x = 0.4) thin films, which show high electrical conductivity and high\ngravimetric capacity for Li insertion. Enhanced cycling performance is achieved\ncompared to previously published end-members Zn3N2 and Sn3N4, showing decreased\nirreversible loss and increased total capacity and cycle stability. The average\nreversible capacity observed is > 1050 mAh/g for all compositions and 1220\nmAh/g for Zn-poor (x = 0.2) films. Extremely Zn-rich films (x = -0.4) show\nimproved adhesion; however, Zn-rich films undergo a phase transformation on the\nfirst cycle. Zn-poor and stoichiometric films do not exhibit significant phase\ntransformations which often plague nitride materials and show no required\noverpotential at the 0.5 V plateau. Cation composition x is explored as a\nmechanism for tuning relevant mechanical and electrochemical properties, such\nas capacity, overpotential, phase transformation, electrical conductivity, and\nadhesion. The lithiation/delithiation experiments confirm the reversible\nelectrochemical reactions. Without any binding additives, the as-deposited\nelectrodes delaminate resulting in fast capacity degradation. We demonstrate\nthe mechanical nature of this degradation through decreased electrode thinning,\nresulting in cells with improved cycling stability due to increased mechanical\nstability. Combining composition and electrochemical analysis, this work\ndemonstrates for the first time composition dependent electrochemical\nproperties for the ternary Zn1-xSn1+xN2 and proposes earth-abundant ternary\nnitride anodes for increased reversible capacity and cycling stability.",
        "positive": "Behavior of Bucky Ball under extreme Internal and External Pressures: We study the behavior of the C60 molecule under very high internal and\nexternal pressure using Tersoff potential. As a result, we calculate the\ncritical internal and external pressures leading to its instability. We also\ncalculate stretching force constant, breathing mode frequency and bulk modulus\nof this molecule. The data estimated here at zero pressure agrees closely to\nthat obtained in earlier calculations. If subjected to extreme pressures the\nmolecule can withstand upto 58.23% of compression and 174.89% of dilation in\nterms of its volume. We also observe that above some critical external pressure\nthe coordination number of the carbon atoms of C60 molecule suddenly increases\nresulting in an abrupt change in the bulk modulus of the molecule."
    },
    {
        "anchor": "First-principles characterisation of spectroscopic and bonding\n  properties of cationic bismuth carbide clusters: Vibrational and electronic absorption spectra calculated at the\n(time-dependent) density functional theory level for the bismuth carbide\nclusters Bi$_{n}$C$_{2n}$$^+$ ($3 \\le n \\le 9$) indicate significant\ndifferences in types of bonding that depend on cluster geometry. Analysis of\nthe electronic charge densities of these clusters highlighted bonding trends\nconsistent with the spectroscopic information. The combined data suggest that\nlarger clusters ($n > 5$) are likely to be kinetically unstable in agreement\nwith the cluster mass distribution obtained in gas-aggregation source\nexperiments. The spectral fingerprints of the different clusters obtained from\nour calculations also suggest that identification of specific\nBi$_{n}$C$_{2n}$$^+$ isomers of should be possible based on infra-red and\noptical absorption spectroscopy.",
        "positive": "Addressing electron-hole correlation in core excitations of solids: An\n  all-electron many-body approach from first principles: We present an ab initio study of core excitations of solid-state materials\nfocussing on the role of electron-hole correlation. In the framework of an\nall-electron implementation of many-body perturbation theory into the exciting\ncode, we investigate three different absorption edges of three materials,\nspanning a broad energy window, with transition energies between a few hundred\nto thousands of eV. Specifically, we consider excitations from the Ti $K$ edge\nin rutile and anatase $\\textrm{TiO}_2$, from the Pb $M_4$ edge in\n$\\textrm{PbI}_2$, and from the Ca $L_{2,3}$ edge in $\\textrm{CaO}$. We show\nthat the electron-hole attraction rules x-ray absorption for deep core states,\nwhen local fields play a minor role. On the other hand, the local-field effects\nintroduced by the exchange interaction between the excited electron and the\nhole dominate excitation processes from shallower core levels, separated by a\nspin-orbit splitting of a few eV. Our approach yields absorption spectra in\ngood agreement with available experimental data, and allows for an in-depth\nanalysis of the results, revealing the electronic contributions to the\nexcitations, as well as their spatial distribution."
    },
    {
        "anchor": "Structure of twisted and buckled bilayer graphene: We study the atomic structure of twisted bilayer graphene, with very small\nmismatch angles ($\\theta \\sim 0.28^0$), a topic of intense recent interest. We\nuse simulations, in which we combine a recently presented semi-empirical\npotential for single-layer graphene, with a new term for out-of-plane\ndeformations, [Jain et al., J. Phys. Chem. C, 119, 2015] and an often-used\ninterlayer potential [Kolmogorov et al., Phys. Rev. B, 71, 2005]. This\ncombination of potentials is computationally cheap but accurate and precise at\nthe same time, allowing us to study very large samples, which is necessary to\nreach very small mismatch angles in periodic samples. By performing large scale\natomistic simulations, we show that the vortices appearing in the Moir\\'e\npattern in the twisted bilayer graphene samples converge to a constant size in\nthe thermodynamic limit. Furthermore, the well known sinusoidal behavior of\nenergy no longer persists once the misorientation angle becomes very small\n($\\theta<1^0$). We also show that there is a significant buckling after the\nrelaxation in the samples, with the buckling height proportional to the system\nsize. These structural properties have direct consequences on the electronic\nand optical properties of bilayer graphene.",
        "positive": "Carrier diffusion in GaN -- a cathodoluminescence study. II: Ambipolar\n  vs. exciton diffusion: We determine the diffusion length of excess carriers in GaN by spatially\nresolved cathodoluminescence spectroscopy utilizing a single quantum well as\ncarrier collector or carrier sink. Monochromatic intensity profiles across the\nquantum well are recorded for temperatures between 10 and 300 K. A classical\ndiffusion model accounts for the profiles acquired between 120 and 300 K, while\nfor temperatures lower than 120 K, a quantum capture process has to be taken\ninto account in addition. Combining the diffusion length extracted from these\nprofiles and the effective carrier lifetime measured by time-resolved\nphotoluminescence experiments, we deduce the carrier diffusivity as a function\nof temperature. The experimental values are found to be close to theoretical\nones for the ambipolar diffusivity of free carriers limited only by intrinsic\nphonon scattering. This agreement is shown to be fortuitous. The high\ndiffusivity at low temperatures instead originates from an increasing\nparticipation of excitons in the diffusion process."
    },
    {
        "anchor": "Ab initio Green-Kubo simulations of heat transport in solids: Method and\n  implementation: Ab initio Green-Kubo (aiGK) simulations of heat transport in solids allow for\nassessing lattice thermal conductivity in anharmonic or complex materials from\nfirst principles. In this work, we present a detailed account of their\npractical application and evaluation with an emphasis on noise reduction and\nfinite-size corrections in semiconductors and insulators. To account for such\ncorrections, we propose strategies in which all necessary numerical parameters\nare chosen based on the dynamical properties displayed during molecular\ndynamics simulations in order to minimize manual intervention. This paves the\nway for applying the aiGK method in semi-automated and high-throughput\nframeworks. The proposed strategies are presented and demonstrated for\ncomputing the lattice thermal conductivity at room temperature in the mildly\nanharmonic periclase MgO, and for the strongly anharmonic marshite CuI.",
        "positive": "From Nanopores to Macropores: Fractal Morphology of Graphite: We present a comprehensive structural characterization of two different\nhighly pure nuclear graphites that compasses all relevant length scales from\nnanometers to sub-mm. This has been achieved by combining several experiments\nand neutron techniques: Small Angle Neutron Scattering (SANS), high-resolution\nSpin Echo SANS (SESANS) and neutron imaging. In this way it is possible to\nprobe an extraordinary broad range of 6 orders of magnitude in length from\nmicroscopic to macroscopic length scales. The results reveal a fractal\nstructure that extends from $ \\sim $ 0.6 nm to 0.6 mm and has surface and mass\nfractal dimensions both very close to 2.5, a value found for percolating\nclusters and fractured ranked surfaces in 3D."
    },
    {
        "anchor": "Energy bands and Wannier-Mott excitons in Zn(P_{1-x}As_{x})_{2} and\n  Zn_{1-x}Cd_{x}P_{2} crystals: Excitonic absorption, reflection and photoluminescence spectra of mixed\nZn(P_{1-x}As_{x})_{2}crystals over the full range of x (0 < x < 1) and\nZn_{1-x}Cd_{x}P_{2} crystals at 0 < x < 0.05 have been studied at low\ntemperatures (1.8 K). The decrease of the energy gap in Zn(P_{1-x}As_{x})_{2}\nat the increase of x occurs slightly sublinearly. The rydbergs of excitonic\nseries in this crystals decrease as well, and the dependences Ry(x) for all\nseries are strongly superlinear at small x. In Zn_{1-x}Cd_{x}P_{2} crystals the\nenergy gap and rydbergs decrease at the increase of x (at 0 < x < 0.05) as\nwell. The dependences of E_{g} and Ry on x are considerably stronger in\nZn(P_{1-x}As_{x})_{2} than in Zn_{1-x}Cd_{x}P_{2}. At the increase of x the\nhalf-width of excitonic absorption lines increases monotonically in both type\ncrystals that is evidence of the increasing role of fluctuations of crystal\npotential.",
        "positive": "Shock and Release Temperatures in Molybdenum: Shock and release temperatures in Mo were calculated, taking account of\nheating from plastic flow predicted using the Steinberg-Guinan model. Plastic\nflow was calculated self-consistently with the shock jump conditions: this is\nnecessary for a rigorous estimate of the locus of shock states accessible. The\ntemperatures obtained were significantly higher than predicted assuming ideal\nhydrodynamic loading. The temperatures were compared with surface emission\nspectrometry measurements for Mo shocked to around 60GPa and then released into\nvacuum or into a LiF window. Shock loading was induced by the impact of a\nplanar projectile, accelerated by high explosive or in a gas gun. Surface\nvelocimetry showed an elastic wave at the start of release from the shocked\nstate; the amplitude of the elastic wave matched the prediction to around 10%,\nindicating that the predicted flow stress in the shocked state was reasonable.\nThe measured temperatures were consistent with the simulations, indicating that\nthe fraction of plastic work converted to heat was in the range 70-100% for\nthese loading conditions."
    },
    {
        "anchor": "Photoinduced anisotropic lattice dynamic response and domain formation\n  in thermoelectric SnSe: Identifying and understanding the mechanisms behind strong phonon-phonon\nscattering in condensed matter systems is critical to maximizing the efficiency\nof thermoelectric devices. To date, the leading method to address this has been\nto meticulously survey the full phonon dispersion of the material in order to\nisolate modes with anomalously large linewidth and temperature-dependence. Here\nwe combine quantitative MeV ultrafast electron diffraction (UED) analysis with\nMonte Carlo based dynamic diffraction simulation and first-principles\ncalculations to directly unveil the soft, anharmonic lattice distortions of\nmodel thermoelectric material SnSe. A small single-crystal sample is\nphotoexcited with ultrafast optical pulses and the soft, anharmonic lattice\ndistortions are isolated using MeV-UED as those associated with long relaxation\ntime and large displacements. We reveal that these modes have interlayer shear\nstrain character, induced mainly by c-axis atomic displacements, resulting in\ndomain formation in the transient state. These findings provide an innovative\napproach to identify mechanisms for ultralow and anisotropic thermal\nconductivity and a promising route to optimizing thermoelectric devices.",
        "positive": "N\u00e9el-type Skyrmion Lattice with Confined Orientation in the Polar\n  Magnetic Semiconductor GaV$_4$S$_8$: Following the early prediction of the skyrmion lattice (SkL) - a periodic\narray of spin vortices - it has been observed recently in various magnetic\ncrystals mostly with chiral structure. Although non-chiral but polar crystals\nwith C$_{nv}$ symmetry were identifed as ideal SkL hosts in pioneering\ntheoretical studies this archetype of SkL has remained experimentally\nunexplored. Here, we report the discovery of a SkL in the polar magnetic\nsemiconductor GaV$_4$S$_8$ with rhombohedral (C$_{3v}$) symmetry and easy axis\nanisotropy. The SkL exists over an unusually broad temperature range compared\nwith other bulk crystals and the orientation of the vortices is not controlled\nby the external magnetic feld but instead confned to the magnetic easy axis.\nSupporting theory attributes these unique features to a new non-chiral or\nN\\'eel-type of SkL describable as a superposition of spin cycloids in contrast\nto the Bloch-type SkL in chiral magnets described in terms of spin helices."
    },
    {
        "anchor": "The direct and indirect optical absorptions of cubic BAs and BSb: Recently, boron arsenide (BAs) has been measured high thermal conductivity in\nthe experiments, great encouraging for the low-power photoelectric devices.\nTherefore, in the present work, we have systematically investigated the direct\nand indirect optical absorptions of BAs and BSb and the doping effect of\ncongeners by using first-principles calculations. We obtain the absorption\nonset corresponding to the value of indirect bandgap by considering the\nphonon-assisted second-order optical absorptions. And the redshift of\nabsorption onset, enhancement and smoothness of optical absorptions spectra are\nalso captured in the temperature-dependent calculations. In order to introduce\none-order absorptions into the visible range, the doping effect of congeners on\noptical absorptions is studied without the assists of phonon. It is found that\nthe decrease of local direct bandgap after doping derives from either the small\nbandgap in the prototypical III-V semiconductors or CBM locating at R$_c$\npoint. Thus, doping of congeners can improve the direct optical absorptions in\nvisible range.",
        "positive": "Anisotropic Magnon Spin Transport in Ultra-thin Spinel Ferrite Thin\n  Films -- Evidence for Anisotropy in Exchange Stiffness: We report measurements of magnon spin transport in a spinel ferrite,\nmagnesium aluminum ferrite $\\mathrm{MgAl_{0.5}Fe_{1.5}O_4}$ (MAFO), which has a\nsubstantial in-plane four-fold magnetic anisotropy. We observe spin diffusion\nlengths $> 0.8$ $\\mathrm{\\mu m}$ at room temperature in 6 nm films, with spin\ndiffusion length 30% longer along the easy axes compared to the hard axes. The\nsign of this difference is opposite to the effects just of anisotropy in the\nmagnetic energy for a uniform magnetic state. We suggest instead that\naccounting for anisotropy in exchange stiffness is necessary to explain these\nresults."
    },
    {
        "anchor": "Crossover from Metal to Insulator in Dense Lithium-Rich Compound\n  $\\textrm{CLi}_{4}$: Crystal structures of $\\textrm{CLi}_4$ compounds are explored through\n\\emph{ab} \\emph{initio} evolutionary methodology. Phase transition from metal\nto semimetal and semiconductor, and eventually to insulator with increasing\npressure are revealed under pressure. Pressure-induced evolution of\nanti-metallization has been described quantitatively by Fermi Surface Filling\nRatio and electron energy band gap using \\emph{ab} \\emph{initio} \\emph{GW}\ncalculations. Anti-metallization is attributed to the hybrid valence electrons\nand their repulsion by core electrons into the lattice interstices. Very weak\nelectron-phonon coupling interactions are found in the metallic phases,\nresulting in very low superconducting temperature.",
        "positive": "Metal-less Metamaterial for Surface Plasmon Polariton guiding and\n  amplification: We propose a novel metamaterial for Surface Plasmon Polarition guiding,\namplification and modulation. Specific example of AlN/GaN Quantum Cascade\nAmplifier and its dispersion engineering are studied in details. The general\noriginal concept of metamaterials based on inclusions of low-dimensional\nquantum structures (artificial atoms) is discussed."
    },
    {
        "anchor": "Morphology control of the magnetization reversal mechanism in Co80Ni20\n  nanomagnets: Nanowires with very different size, shape, morphology and crystal symmetry\ncan give rise to a wide ensemble of magnetic behaviors whose optimization\ndetermines their applications in nanomagnets. We present here an experimental\nwork on the shape and morphological dependence of the magnetization reversal\nmechanism in weakly interacting Co80Ni20 hexagonal-close-packed nanowires.\nNon-agglomerated nanowires (with length L and diameter d) with a controlled\nshape going from quasi perfect cylinders to diabolos, have been studied inside\ntheir polyol solution in order to avoid any oxidation process. The coercive\nfield HC was found to follow a standard behavior and to be optimized for an\naspect ratio L/d > 15. Interestingly, an unexpected behavior was observed as\nfunction of the head morphology leading to the strange situation where a\ndiabolo shaped nanowire is a better nanomagnet than a cylinder. This\nparadoxical behavior can be ascribed to the growth-competition between the\naspect ratio L/d and the head morphology ratio d/D (D being the head width).\nOur experimental results clearly show the importance of the independent\nparameter (t = head thickness) that needs to be considered in addition to the\nshape aspect ratio (L/d) in order to fully describe the nanomagnets magnetic\nbehavior. Micromagnetic simulations well support the experimental results and\nbring important insights for future optimization of the nanomagnets morphology",
        "positive": "Excitation energy dependence of electron-phonon interaction in ZnO\n  nanoparticles: Raman spectroscopic investigations are carried out on ZnO nanoparticles for\nvarious photon energies. Intensities of E1-LO and E2 modes exhibit large\nchanges as the excitation energy varied from 2.41 to 3.815 eV, signifying\nsubstantially large contribution of Frohlich interaction to the Raman\npolarizability as compared to deformation potential close to the resonance.\nRelative strength of these two mechanisms is estimated for the first time in\nnanoparticles and compared with those in the bulk."
    },
    {
        "anchor": "Efficient method to calculate total energies of large nanoclusters: We present an approach to calculate total energies of nanoclusters based on\nfirst principles estimates. For very large clusters the total energy can be\nseparated into surface, edge and corner energies, in addition to bulk\ncontributions. Using this separation and estimating these with direct, first\nprinciples calculations, together with the relevant chemical potentials, we\nhave calculated the total energies of Cu and CdSe tetrahedrons containing a\nlarge number of atoms. In our work we consider polyhedral clusters so that in\naddition our work provides direct information on relaxation. For Cu the effects\nare very small and the clusters vary uniformly from very small to very large\nsizes. For CdSe there are important variations in surface and edge structures\nfor specific sizes; nevertheless, the approach can be used to extrapolate to\nlarge non-stoichiometric clusters with polar surfaces.",
        "positive": "The impact of valley profile on the mobility and Kerr rotation of\n  transition metal dichalcogenides: The transport and optical properties of semiconducting transition metal\ndichalcogenides around room temperature are dictated by electron-phonon\nscattering mechanisms within a complex, spin-textured and multi-valley\nelectronic landscape. The relative positions of the valleys are critical, yet\nthey are sensitive to external parameters and very difficult to determine\ndirectly. We propose a first-principle model as a function valley positions to\ncalculate carrier mobility and Kerr rotation angles. The model brings valuable\ninsights, as well as quantitative predictions of macroscopic properties for a\nwide range of carrier density. The doping-dependant mobility displays a\ncharacteristic peak, the height depending on the position of the valleys. The\nKerr rotation signal is enhanced when same spin-valleys are aligned, and\nquenched when opposite spin-valleys are populated. We provide guidelines to\noptimize these quantities with respect to experimental parameters, as well as\nthe theoretical support for \\emph{in situ} characterization of the valley\npositions."
    },
    {
        "anchor": "Atomistic treatment of depolarizing energy and field in ferroelectric\n  nanostructures: An {\\it atomistic} approach allowing an accurate and efficient treatment of\ndepolarizing energy and field in {\\it any} low-dimensional ferroelectric\nstructure is developed. Application of this approach demonstrates the limits of\nthe widely used continuum model (even) for simple test cases. Moreover,\nimplementation of this approach within a first-principles-based model reveals\nan unusual phase transition -- from a state exhibiting a spontaneous\npolarization to a phase associated with a toroid moment of polarization -- in a\nferroelectric nanodot for a critical value of the depolarizing field.",
        "positive": "Observation of an unusual field dependent slow magnetic relaxation and\n  two distinct transitions in a family of new complexes: An unusual field dependent slow magnetic relaxation and two distinct\ntransitions were observed in a family of new rare earth-transition metal\ncomplexes, [Ln (bipy) (H$_{2}$O)$_{4}$ M(CN)$_{6}$] $\\cdot $1.5 (bipy) $ \\cdot\n$ 4H$_{2}$O (bipy = 2,2'-bipyridine; Ln = Gd$^{3+}$,Y$^{3+}$; M = Fe$ ^{3+}$,\nCo$^{3+}$). The novel magnetic relaxation, which is quite different from those\nin normal spin glasses and superparamagnets but very resembles qualitatively\nthose in single-molecule magnet Mn$_{12}$-Ac even if they possess different\nstructures, might be attributed to the presence of frustration that is\nincrementally unveiled by the external magnetic field. The two distinct\ntransitions in [GdFe] were presumed from DC and AC susceptibility as well as\nheat capacity measurements."
    },
    {
        "anchor": "Phase stability of chromium based compensated ferrimagnets with inverse\n  Heusler structure: Chromium based inverse Heusler compounds of the type Cr2YZ (Y=Co, Fe; Z=Al,\nGa, In, Si, Ge, Sn) have been proposed as fully compensated half-metallic\nferrimagnets. Such materials are of large interest for spintronics because they\ncombine small magnetic moment with high spin polarization over a wide\ntemperature range. We assess their thermodynamic stability by their formation\nenthalpies obtained from density functional theory calculations. All compounds\nunder investigation are unstable. Cr2FeSi and Cr2CoAl are stable with respect\nto the elemental constituents, but decompose into binary phases. Cr2FeGe,\nCr2CoGa, Cr2FeSn and Cr2CoIn are found to be unstable with respect to their\nelemental constituents. We identify possible binary decompositions.",
        "positive": "Evaluating the exfoliation of two-dimensional materials with a Green's\n  function surface model: Previous methods for the evaluation of the exfoliation of two-dimensional\n(2D) layered materials have drawbacks in computational efficiency and are\nunable to describe cases with semi-infinite substrates. Based on a Green's\nfunction surface (GFS) model, here we develop a new approach to efficiently\ndetermine the tendency of exfoliation of 2D materials from their bulk crystals\nor semi-infinite substrates. By constructing appropriate surface\nconfigurations, we may calculate the exfoliation energy more precisely and\nquickly than the traditional way with the slab model. Furthermore, the GFS\napproach can provide angle-resolved photoemission spectroscopy (ARPES) of\nsurface systems for direct comparison with experimental data. Our findings\nindicate that the GFS approach is powerful for studies of 2D materials and\nvarious surface problems."
    },
    {
        "anchor": "The Emerging Weak Antilocalization Effect in Semimetal\n  Ta$_{0.7}$Nb$_{0.3}$Sb$_2$ Single Crystal: Weak antilocalization (WAL) effect is commonly observed in 2D systems, or 3D\ntopological insulators, topological semimetal systems. Here we report the clear\nsign of WAL effect in high quality Ta$_{0.7}$Nb$_{0.3}$Sb$_2$ single crystals,\nin below 50$^\\circ$ K region. The chemical vapor transport method was employed\nto grow the single crystal samples, the high crystallization quality and\nuniform element distribution are verified by X-ray diffractions and electron\nmicroscopy techniques. Employing the Hall effect and two-band model fitting,\nthe high carrier mobility (> 1000 cm$^2$V$^{-1}$s$^{-1}$ in 2 to 300$^\\circ$ K\nregion) and off-compensation electron/hole ratio are obtained. Due to the\ndifferent angular dependence of WAL effect and the fermiology of\nTa$_{0.7}$Nb$_{0.3}$Sb$_2$ single crystal, interesting magnetic-field-induced\nsymmetry change is observed in angular magnetoresistance. These interesting\ntransport properties will lead to more theoretical and applicational\nexploration in Ta$_{0.7}$Nb$_{0.3}$Sb$_2$ and related semimetal materials.",
        "positive": "Robust 3.7 V-Na$_{2/3}$[Cu$_{1/3}$Mn$_{2/3}$]O$_2$ Cathode for Na-ion\n  Batteries: Na-ion batteries (NIBs), which are recognized as a next-generation\nalternative technology for energy storage, still suffer from commercialization\nconstraints due to the lack of low-cost, high-performance cathode materials.\nSince our first discovery of Cu$^{3+}$/Cu$^{2+}$ electrochemistry in 2014,\nnumerous Cu-substituted/doped materials have been designed for NIBs. However\nfor almost ten years, the potential of Cu$^{3+}$/Cu$^{2+}$ electrochemistry has\nbeen grossly underappreciated and normally regarded as a semielectrochemically\nactive redox. Here, we re-synthesized P2-Na$_{2/3}$[Cu$_{1/3}$Mn$_{2/3}$]O$_2$\nand reinterpreted it as a high-voltage, cost-efficient, air-stable, long-life,\nand high-rate cathode material for NIBs, which demonstrates a high operating\nvoltage of 3.7 V and a completely active Cu$^{3+}$/Cu$^{2+}$ redox reaction.\nThe 2.3 Ah cylindrical cells exhibit excellent cycling (93.1% capacity after\n2000 cycles), high rate (97.2% capacity at 10C rate), good low-temperature\nperformance (86.6% capacity at -30$^\\circ$C), and high safety, based on which,\na 56 V-11.5 Ah battery pack for E-bikes is successfully constructed, exhibiting\nstable cycling (96.5% capacity at the 800th cycle) and a long driving distance\n(36 km, tester weight 65 kg). This work offers a commercially feasible cathode\nmaterial for low-cost, high-voltage NIBs, paving the way for advanced NIBs in\npower and stationary energy storage applications."
    },
    {
        "anchor": "Capacity Fade due to Side-reactions in Silicon Anodes in Lithium-ion\n  Batteries: It is shown that continuously occurring electrolyte-reduction reaction on\nfreshly-exposed electrode surfaces during lithiation/delithiation cycles causes\nthe lowering of cycling efficiency, and hence, capacity fade in well-cycled\nsilicon anodes in lithium-ion batteries. Using galvanostatic\nlithiation/delithiation data from multiple cycles on a Li/Si half-cell, a\nmethodology to separate the charge due to the main reaction\n(lithiation/delithiation of Si) from the side-reaction (electrolyte-reduction)\nis presented. The rate of this parasitic side reaction is estimated on\nwell-cycled amorphous silicon thin-film electrodes at ambient temperature for\nthe following three commonly-used lithium-ion electrolyte formulations:\nmixtures of ethylene carbonate and diethylene carbonate (EC:DEC) with and\nwithout a fluoroethylene carbonate (FEC) additive, and propylene carbonate\n(PC), all containing 1.2 M lithium hexafluorophosphate. Among the three\nformulations, the electrolyte containing EC:DEC with the FEC additive exhibits\nthe lowest coulombic losses due to side-reactions, followed by PC, and EC:DEC\nwithout the FEC additive (i.e., EC:DEC + FEC > PC > EC:DEC). The importance of\nestimating side-reaction rates on a well-cycled electrode is discussed in the\ncontext of self-discharge, capacity fade, development of battery management\nsystem algorithms and precise mathematical modeling of lithium-ion batteries.",
        "positive": "Thermal Resistances of Thin-Films of Small Molecule Organic\n  Semiconductors: We have measured the thermal resistances of thin films of the small molecule\norganic semiconductors bis(triisopropylsilylethynyl) pentacene (TIPS-pn),\nbis(triethylsilylethynyl) anthradithiophene (TES-ADT) and difluoro\nbis(triethylsilylethynyl) anthradithiophene (diF-TES-ADT). For each material,\nseveral films of different thicknesses have been measured to separate the\neffects of intrinsic thermal conductivity from interface thermal resistance.\nFor non-crystalline films of all three materials, with thicknesses ranging from\n< 100 nm to > 4 microns, the thermal conductivities are similar to that of\npolymers and over an order of magnitude smaller than that of the crystals,\nreflecting the large reduction in phonon mean-free path in the films. Thin (<\n205 nm) crystalline films of TES-ADT, prepared by vapor-annealing spin-cast\nfilms, have also been measured, but for these the thermal resistances are\ndominated by interface scattering."
    },
    {
        "anchor": "A multiscale generative model to understand disorder in domain\n  boundaries: A continuing challenge in atomic resolution microscopy is to identify\nsignificant structural motifs and their assembly rules in synthesized materials\nwith limited observations. Here we propose and validate a simple and effective\nhybrid generative model capable of predicting unseen domain boundaries in a\npotassium sodium niobate thin film from only a small number of observations,\nwithout expensive first-principles calculation. Our results demonstrate that\ncomplicated domain boundary structures can arise from simple interpretable\nlocal rules, played out probabilistically. We also found new significant\ntileable boundary motifs and evidence that our system creates domain boundaries\nwith the highest entropy. More broadly, our work shows that simple yet\ninterpretable machine learning models can help us describe and understand the\nnature and origin of disorder in complex materials.",
        "positive": "Machine Learning-Aided Discovery of Superionic Solid-State Electrolyte\n  for Li-Ion Batteries: Li-Ion Solid-State Electrolytes (Li-SSEs) are a promising solution that\nresolves the critical issues of conventional Li-Ion Batteries (LIBs) such as\npoor ionic conductivity, interfacial instability, and dendrites growth. In this\nstudy, a platform consisting of a high-throughput screening and a\nmachine-learning surrogate model for discovering superionic Li-SSEs among\n20,237 Li-containing materials is developed. For the training database, the\nionic conductivity of Na SuperIonic CONductor (NASICON) and Li SuperIonic\nCONductor (LISICON) type SSEs are obtained from the previous literature. Then,\nthe chemical descriptor (CD) and additional structural properties are used as\nmachine-readable features. Li-SSE candidates are selected through the screening\ncriteria, and the prediction on the ionic conductivity of those is followed.\nThen, to reduce uncertainty in the surrogate model, the ensemble method by\nconsidering the best-performing two models is employed, whose mean prediction\naccuracy is 0.843 and 0.829, respectively. Furthermore, first-principles\ncalculations are conducted for confirming the ionic conductivity of the strong\ncandidates. Finally, six potential superionic Li-SSEs that have not previously\nbeen investigated are proposed. We believe that the constructed platform can\naccelerate the search for Li-SSEs with high ionic conductivity at minimum cost."
    },
    {
        "anchor": "Effective Lifetime of Non-Equilibrium Carriers in Semiconductors from\n  Non-Adiabatic Molecular Dynamics Simulations: The lifetime of non-equilibrium electrons and holes in semiconductors is\ncrucial for solar cell and optoelectronic applications. Non-adiabatic molecular\ndynamics (NAMD) simulations based on time-dependent density functional theory\n(TDDFT) are widely used to study excited-state carrier dynamics. However, the\ncalculated carrier lifetimes are often different from experimental results by\norders of magnitude. In this work, by revisiting the definition of carrier\nlifetime and considering different recombination mechanisms, we report a\nsystematic procedure for calculating the effective carrier lifetime in\nrealistic semiconductor crystals that can be compared directly to experimental\nmeasurements. The procedure shows that considering all recombination mechanisms\nand using reasonable densities of carriers and defects are crucial in\ncalculating the effective lifetime. When NAMD simulations consider only\nShockey-Read-Hall (SRH) defect-assisted and band-to-band non-radiative\nrecombination while neglect band-to-band radiative recombination, and the\ndensities of non-equilibrium carriers and defects in supercell simulations are\nmuch higher than those in realistic semiconductors under solar illumination,\nthe calculated lifetimes are ineffective and thus differ from experiments.\nUsing our procedure, the calculated effective lifetime of the halide perovskite\nCH3NH3PbI3 agrees with experiments. It is mainly determined by band-to-band\nradiative and defect-assisted non-radiative recombination, while band-to-band\nnon-radiative recombination is negligible. These results indicate that it is\npossible to calculate carrier lifetimes accurately based on NAMD simulations,\nbut the directly calculated values should be converted to effective lifetimes\nfor comparison to experiments. The revised procedure can be widely applied in\nfuture carrier lifetime simulations.",
        "positive": "Exciton-exciton interaction in transition metal dichalcogenide\n  monolayers and van der Waals heterostructures: Due to a strong Coulomb interaction, excitons dominate the excitation\nkinetics in 2D materials. While Coulomb-scattering between electrons has been\nwell studied, the interaction of excitons is more challenging and remains to be\nexplored. As neutral composite bosons consisting of electrons and holes,\nexcitons show a non-trivial scattering dynamics. Here, we study on microscopic\nfooting exciton-exciton interaction in transition-metal dichalcogenides and\nrelated van der Waals heterostructures. We demonstrate that the crucial\ncriterion for efficient scattering is a large electron/hole mass asymmetry\ngiving rise to internal charge inhomogeneities of excitons and emphasizing\ntheir cobosonic substructure. Furthermore, both exchange and direct\nexciton-exciton interactions are boosted by enhanced exciton Bohr radii. We\nalso predict an unexpected temperature dependence that is usually associated to\nphonon-driven scattering and we reveal an orders of magnitude stronger\ninteraction of interlayer excitons due to their permanent dipole moment. The\ndeveloped approach can be generalized to arbitrary material systems and will\nhelp to study strongly correlated exciton systems, such as moire super\nlattices."
    },
    {
        "anchor": "Anomalous Hall and Nernst effects in ferrimagnetic Mn$_4$N films:\n  possible interpretation and prospect for enhancement: Ferrimagnetic Mn$_4$N is a promising material for heat flux sensors based on\nthe anomalous Nernst effect (ANE) because of its sizable uniaxial magnetic\nanisotropy ($K_{\\rm u}$) and low saturation magnetization ($M_{\\rm s}$). We\nexperimentally and theoretically investigated the ANE and anomalous Hall effect\nin sputter-deposited Mn$_4$N films. It was revealed that the observed negative\nanomalous Hall conductivity ($\\sigma_{xy}$) could be explained by two different\ncoexisting magnetic structures, that is, a dominant magnetic structure with\nhigh $K_{\\rm u}$ contaminated by another structure with negligible $K_{\\rm u}$\nowing to an imperfect degree of order of nitrogen. The observed transverse\nthermoelectric power ($S_{\\rm ANE}$) of $+0.5\\, \\mu{\\rm V/K}$ at $300\\, {\\rm\nK}$ gave a transverse thermoelectric coefficient ($\\alpha_{xy}$) of $+0.34\\,\n{\\rm A/(m \\cdot K)}$, which was smaller than the value predicted from\nfirst-principles calculation. The interpretation for $\\alpha_{xy}$ based on the\nfirst-principles calculations led us to conclude that the realization of single\nmagnetic structure with high $K_{\\rm u}$ and optimal adjustment of the Fermi\nlevel are promising approaches to enhance $S_{\\rm ANE}$ in Mn$_4$N through the\nsign reversal of $\\sigma_{xy}$ and the enlargement of $\\alpha_{xy}$ up to a\ntheoretical value of $1.77\\, {\\rm A/(m \\cdot K)}$.",
        "positive": "Tailored surfaces of perovskite oxide substrates for conducted growth of\n  thin films: Oxide electronics relies on the availability of epitaxial oxide thin films.\nThe extreme flexibility of the chemical composition of ABO3 perovskites and the\nbroad spectrum of properties they cover, inspire the creativity of scientists\nand place perovskites in the lead of functional materials for advanced\ntechnologies. Moreover, emerging properties are being discovered at interfaces\nbetween distinct perovskites that could not be anticipated on the basis of\nthose of the adjacent epitaxial layers. All dreamed new prospects require the\nuse of suitable substrates for epitaxial growth. Perovskite single crystals are\nthe workhorses of this activity and understanding and controlling their surface\nproperties have become critical. In this tutorial review we will chiefly focus\non the impact of the morphology and composition of the surface of ABO3\nperovskite substrates on the growth mechanisms and properties of thin films\nepitaxially grown on them. As SrTiO3 is the most popular substrate, we will\nmostly concentrate on describing the current understanding and achievements for\nit. Illustrative examples of other perovskite substrates (LaAlO3, LSAT and\nDyScO3) will be also included. We will show that distinct chemical terminations\ncan exist on the surfaces used for growth and we will review methods employed\neither to select the most appropriate one for specific growth to allow, for\ninstance, tailoring the ultimate outmost epilayer, or to induce self-ordering\nto engineer long-range nanoscale patterns of chemical terminations. We will\ndemonstrate the capacity of this knowledge by the growth of low-dimensional\norganic and inorganic structures."
    },
    {
        "anchor": "Preparation and photoemission investigation of bulk-like a-Mn films on\n  W(110): We report the successful stabilization of a thick bulk-like, distorted\n$\\alpha$-Mn film with (110) orientation on a W(110) substrate. The observed\n$(3\\times3)$ overstructure for the Mn film with respect to the original W(110)\nlow-energy electron diffraction pattern is consistent with the presented\nstructure model. The possibility to stabilize such a pseudomorphic Mn film is\nsupported by density functional total energy calculations. Angle-resolved\nphotoemission spectra of the stabilized $\\alpha$-Mn(110) film show weak\ndispersions of the valence band electronic states in accordance with the large\nunit cell.",
        "positive": "Infuence of correlation effects on the of magneto-optical properties of\n  half-metallic ferromagnet NiMnSb: The magneto-optical spectra of NiMnSb were calculated in the framework of the\nLocal Spin Density Approximation (LSDA) combined with Dynamical Mean-Field\nTheory (DMFT). Comparing with results based on plain LSDA, an additional\naccount of many-body correlations via DMFT results in a noticably improved\nagreement of the theoretical Kerr-rotation and ellipticity spectra with\ncorresponding experimental data."
    },
    {
        "anchor": "Large spin pumping effect in antisymmetric precession of\n  Ni$_{79}$Fe$_{21}$/Ru/Ni$_{79}$Fe$_{21}$: In magnetic trilayer structures, a contribution to the Gilbert damping of\nferromagnetic resonance arises from spin currents pumped from one layer to\nanother. This contribution has been demonstrated for layers with weakly\ncoupled, separated resonances, where magnetization dynamics are excited\npredominantly in one layer and the other layer acts as a spin sink. Here we\nshow that trilayer structures in which magnetizations are excited\nsimultaneously, antisymmetrically, show a spin-pumping effect roughly twice as\nlarge. The antisymmetric (optical) mode of antiferromagnetically coupled\nNi$_{79}$Fe$_{21}$(8nm)/Ru/Ni$_{79}$Fe$_{21}$(8nm) trilayers shows a Gilbert\ndamping constant greater than that of the symmetric (acoustic) mode by an\namount as large as the intrinsic damping of Py ($\\Delta\n\\alpha\\simeq\\textrm{0.006}$). The effect is shown equally in field-normal and\nfield-parallel to film plane geometries over 3-25 GHz. The results confirm a\nprediction of the spin pumping model and have implications for the use of\nsynthetic antiferromagnets (SAF)-structures in GHz devices.",
        "positive": "Metamagnetic transitions and anomalous magnetoresistance in\n  EuAg$_4$As$_2$ single crystal: In this paper, the magnetic and transport properties were systematically\nstudied for EuAg$_4$As$_2$ single crystals, crystallizing in a centrosymmetric\ntrigonal CaCu$_4$P$_2$ type structure. It was confirmed that two magnetic\ntransitions occur at $\\textit{T}$$_{N1}$ = 10 K and $\\textit{T}$$_{N2}$ = 15 K,\nrespectively. With the increasing field, the two transitions are noticeably\ndriven to lower temperature. At low temperatures, applying a magnetic field in\nthe $\\textit{ab}$ plane induces two successive metamagnetic transitions. For\nboth $\\textit{H}$ $\\parallel$ $\\textit{ab}$ and $\\textit{H}$ $\\parallel$\n$\\textit{c}$, EuAg$_4$As$_2$ shows a positive, unexpected large\nmagnetoresistance (up to 202\\%) at low fields below 10 K, and a large negative\nmagnetoresistance (up to -78\\%) at high fields/intermediate temperatures. Such\nanomalous field dependence of magnetoresistance may have potential application\nin the future magnetic sensors. Finally, the magnetic phase diagrams of\nEuAg$_{4}$As$_{2}$ were constructed for both $\\textit{H}$ $\\parallel$\n$\\textit{ab}$ and $\\textit{H}$ $\\parallel$ $\\textit{c}$."
    },
    {
        "anchor": "Theoretical Analysis of STM Experiments at Rutile TiO_2 Surfaces: A first-principles atomic orbital-based electronic structure method is used\nto investigate the low index surfaces of rutile Titanium Dioxide. The method is\nrelatively cheap in computational terms, making it attractive for the study of\noxide surfaces, many of which undergo large reconstructions, and may be\ngoverned by the presence of Oxygen vacancy defects. Calculated surface charge\ndensities are presented for low-index surfaces of TiO$_2$, and the relation of\nthese results to experimental STM images is discussed. Atomic resolution images\nat these surfaces tend to be produced at positive bias, probing states which\nlargely consist of unoccupied Ti 3$d$ bands, with a small contribution from O\n2$p$. These experiments are particularly interesting since the O atoms tend to\nsit up to 1 angstrom above the Ti atoms, so providing a play-off between\nelectronic and geometric structure in image formation.",
        "positive": "Large Bulk Piezophotovoltaic Effect of Monolayer $2H$-MoS$_2$: The bulk photovoltaic effect in noncentrosymmetric materials is an intriguing\nphysical phenomenon that holds potential for high-efficiency energy harvesting.\nHere, we study the shift current bulk photovoltaic effect in the transition\nmetal dichalcogenide MoS$_2$. We present a simple automated method to guide\nmaterials design and use it to uncover a distortion to monolayer $2H$-MoS$_2$\nthat dramatically enhances the integrated shift current. Using this distortion,\nwe show that overlap in the Brillouin zone of the distributions of the shift\nvector (a quantity measuring the net displacement in real space of coherent\nwave packets during excitation) and the transition intensity is crucial for\nincreasing the shift current. The distortion pattern is related to the material\npolarization and can be realized through an applied electric field via the\nconverse piezoelectric effect. This finding suggests an additional method to\nengineer the shift current response of materials to augment previously reported\nmethods using mechanical strain."
    },
    {
        "anchor": "Geometrically frustrated GdInO$_3$: An exotic system to study negative\n  thermal expansion and spin-lattice coupling: In this article, we report negative thermal expansion and spin frustration in\nhexagonal GdInO$_{3}$. Rietveld refinement of the XRD patterns reveal that the\nnegative thermal expansion in the temperature range of 50-100K stems from the\ntriangular lattice of Gd$^{3+}$ ions. At low temperature, the downward\ndeviation of the inverse susceptibility ($\\chi^{-1}$) vs. $T$ plot from the\nCurie-Weiss law indicates spin frustration which inhibits long-range magnetic\nordering down to 2K. Magnetostriction measurements clearly demonstrate a strong\nspin-lattice coupling. Low temperature anomalous phonon softening, as obtained\nfrom temperature dependent Raman measurements, also reveals the same. Our\nexperimental observations are supported by first principles density functional\ntheory calculations of the electronic and phonon dispersion of GdInO$_3$. The\ncalculations suggest that the GdInO$_3$ lattice is highly frustrated at low\ntemperature. Further, the calculated normal mode frequencies of the Gd related\n$\\Gamma$ point phonons are found to depend on the magnetic structure of the\nlattice, suggesting significant magneto-elastic coupling.",
        "positive": "Strength of the Hubbard potential and its modification by breathing\n  distortion in $\\text{BaBiO}_{3}$: $\\text{BaBiO}_{3}$ compound is known as an archetype example of a\nthree-dimensional Holstein model with the realization of the charge density\nwave state at half-filling and the superconducting state when doped. Although\nmany works are devoted to the study of the electron-phonon interaction in\n$\\text{BaBiO}_{3}$, the influence of the electron-electron Hubbard interaction\non the electronic structure in this system is still under quest. In our work,\nwe obtain an analytical expression for the screened Coulomb potential, and\nalong with the basis of \\textit{ab initio}-computed maximally localized Wannier\norbitals, we quantitatively estimate the magnitude of the effective on-site\nHubbard potential scrutinizing the effects of distortion of the crystal\nlattice. We show that a proper inclusion of the electron-electron interactions\ninto the Holstein model significantly lowers the value of the underlying\nelectron-phonon coupling. Finally, we find that the amplitudes of the repulsive\nelectron-electron potential and its attractive counterpart mediated by the\nelectron-phonon coupling are rather comparable. This may open a way for a\nrealization of the intermediate phase of $\\text{BaBiO}_{3}$ in terms of the\nHolstein-Hubbard model."
    },
    {
        "anchor": "Cesium-involved electron transfer and electron-electron interaction in\n  high-pressure metallic CsPbI3: Electron-phonon coupling was believed to govern the carrier transport in\nhalide perovskites and related phases. Here we demonstrate that\nelectron-electron interaction plays a direct and prominent role in the\nlow-temperature electrical transport of compressed CsPbI3 and renders Fermi\nliquid (FL)-like behavior. By compressing {\\delta}-CsPbI3 to 80 GPa, an\ninsulator-to-metal transition occurs, concomitant with the completion of a\nsluggish structural transition from the one-dimensional (1D) Pnma ({\\delta})\nphase to a 3D Pmn21 ({\\epsilon}) phase. Deviation from FL behavior is observed\nin CsPbI3 upon entering the metallic {\\epsilon} phase, which progressively\nevolves into a FL-like state at 186 GPa. First-principles density functional\ntheory calculations reveal that the enhanced electron-electron coupling is\nrelated to the Cs-involved electron transfer and sudden increase of the 5d\nstate occupation of the high-pressure {\\epsilon} phase. Our study presents a\npromising strategy for tuning the electronic interaction in halide perovskites\nfor realizing intriguing electronic states.",
        "positive": "Epitaxial ferromagnetic semiconductor GdN thin films on Si substrate: This paper has been withdrawn by the author"
    },
    {
        "anchor": "Ferroelectricity driven-resistive switching and Schottky barrier\n  modulation at CoPt/MgZnO interface for non-volatile memories: Ferroelectric memristors have attracted much attention as a type of\nnonvolatile resistance switching memories in neuromorphic computing, image\nrecognition, and information storage. Their resistance switching mechanisms\nhave been studied several times in perovskite and complicated materials\nsystems. It was interpreted as the modulation of carrier transport by\npolarization control over Schottky barriers. Here, we experimentally report the\nisothermal resistive switching across a CoPt/MgZnO Schottky barrier using a\nsimple binary semiconductor. The crystal and texture properties showed\nhigh-quality and single-crystal Co$_{0.30}$Pt$_{0.70}$/Mg$_{0.20}$Zn$_{0.80}$O\nhetero-junctions. The resistive switching was examined by an electric-field\ncooling method that exhibited a ferroelectric T$_C$ of MgZnO close to the bulk\nvalue. The resistive switching across CoPt/MgZnO Schottky barrier was\naccompanied by a change in the Schottky barrier height of 26.5 meV due to an\ninterfacial charge increase and/or orbital hybridization induced reversal of\nMgZnO polarization. The magnitude of the reversed polarization was estimated to\nbe a reasonable value of 3.0 (8.25) $\\mu$ C/cm$^2$ at 300 K (2 K). These\nfindings demonstrated the utilities of CoPt/MgZnO interface as a potential\ncandidate for ferroelectric memristors and can be extended to probe the\nresistive switching of other hexagonal ferroelectric materials.",
        "positive": "Spin-glass state induced by Mn-doping into a moderate gap layered\n  semiconductor SnSe$_2$: Various types of magnetism can appear in emerging quantum materials such as\nvan der Waals layered ones. Here, we report the successful doping of manganese\natoms into a post-transition metal dichalcogenide semiconductor: SnSe$_2$. We\nsynthesized a single crystal Sn$_{1-x}$Mn$_x$Se$_{2}$ with $\\textit{x}$ = 0.04\nby the chemical vapor transport (CVT) method and characterized it by x-ray\ndiffraction (XRD) and energy-dispersive x-ray spectroscopy (EDS). The magnetic\nproperties indicated a competition between coexisting ferromagnetic and\nantiferromagnetic interactions, from the temperature dependence of the\nmagnetization, together with magnetic hysteresis loops. This means that\nmagnetic clusters having ferromagnetic interaction within a cluster form and\nthe short-range antiferromagnetic interaction works between the clusters; a\nspin-glass state appears below ~ 60 K. Furthermore, we confirmed by $\\textit{ab\ninitio}$ calculations that the ferromagnetic interaction comes from the\n3$\\textit{d}$ electrons of the manganese dopant. Our results offer a new\nmaterial platform to understand and utilize the magnetism in the van der Waals\nlayered materials."
    },
    {
        "anchor": "Ferromagnetism and quantum anomalous Hall effect in one-side-saturated\n  buckled honeycomb lattices: The recently synthesized silicene as well as theoretically discussed\ngermanene are examples of buckled honeycomb structures. The buckled structures\nallow one to manipulate asymmetry between two underlying sublattices of\nhoneycomb structures. Here by taking germanene as a prototype of buckled\nhoneycomb lattices, we explore magnetism induced by breaking sublattice\nsymmetry through saturating chemical bonds on one-side of the buckled honeycomb\nlattice. It is shown that when fractions of chemical bonds on one-side are\nsaturated, two narrow bands always exist at half filling. Furthermore, the\nnarrow bands generally support flat band ferromagnetism in the presence of the\nHubbard $U$ interaction. The induced magnetization is directly related to the\nsaturation fraction and is thus controllable in magnitude through the\nsaturation fraction. Most importantly, we find that depending on the saturation\nfraction, the ground state of an one-side saturated germanene may become a\nquantum anomalous Hall (QAH) insulator characterized by a Chern number that\nvanishes for larger magnetization. The non-vanishing Chern number for smaller\nmagnetization implies that the associated quantum Hall effect tends to survive\nat high temperatures. Our findings provide a potential method to engineer\nbuckled honeycomb structures into high-temperature QAH insulators.",
        "positive": "Chiral Quantum well Rashba splitting in Sb monolayer on Au(111): We present atomic and electronic structure investigations of Single-layer\nSb(110) rhombohedral crystal formed on Au(111) substrate. Low energy electron\ndiffraction (LEED) and scanning tunneling microscopy (STM) reveal a pure 2D Sb\nstripe structure, composed by a pair of Sb(110) unit cell located in a chiral\nconfiguration with mirror symmetry broken along the x axis direction. Based on\nangle-resolved photoemission spectroscopy (ARPES) measurement and Sb-weighted\nband structure from density functional theory calculations, we report the\nunambiguous determination of one pair of Rashba-type splitting band from the 2D\nSb film, exhibiting a chiral symmetry in the electronic structure with the\ncrossing point located at point and point, respectively. Moreover, From dI/dV\nspectra and calculated density of states(DOS), the quantum well(QW) Rashba-type\nstates at different energy induced by the in-plane mirror symmetry broken in Sb\nstripe structure have been identified, and the orbital decomposition of\nprojected band structure indicates hybridization between Sb py state and Au\nstate can modify the spin splitting of QW states due to the intrinsic large SOC\nof Au state introduced into the QW states."
    },
    {
        "anchor": "Deformation of micrometer and mm-sized Fe2.4wt.%Si single- and\n  bi-crystals with a high angle grain boundary at room temperature: Plasticity in body-centred cubic (BCC) metals, including dislocation\ninteractions at grain boundaries, is much less understood than in face-centred\ncubic (FCC) metals. At low temperatures additional resistance to dislocation\nmotion due to the Peierls barrier becomes important, which increases the\ncomplexity of plasticity. Iron-silicon steel is an interesting, model BCC\nmaterial since the evolution of the dislocation structure in\nspecifically-oriented grains and at particular grain boundaries have\nfar-reaching effects not only on the deformation behaviour but also on the\nmagnetic properties, which are important in its final application as electrical\nsteel. In this study, two different orientations of micropillars (1, 2, 4\nmicrons in diameter) and macropillars (2500 microns) and their corresponding bi\ncrystals are analysed after compression experiments with respect to the effect\nof size on strength and dislocation structures. Using different experimental\nmethods, such as slip trace analysis, plane tilt analysis and cross-sectional\nEBSD, we show that direct slip transmission occurs, and different slip systems\nare active in the bi-crystals compared to their single-crystal counterparts.\nHowever, in spite of direct transmission and a very high transmission factor,\ndislocation pile-up at the grain boundary is also observed at early stages of\ndeformation. Moreover, an effect of size scaling with the pillar size in single\ncrystals and the grain size in bi-crystals is found, which is consistent with\ninvestigations elsewhere in FCC metals.",
        "positive": "Luminescence of Natural $\u03b1$-Quartz Crystal with Aluminum, Alkali\n  and Noble Ions Impurities: Photoluminescence and thermally stimulated luminescence of synthetic and\nnatural (morion and smoky) $\\alpha$-quartz crystals doped with aluminum and\nalkali ions were studied. The photoluminescence spectrum is characterized with\nthe main blue band around 400 nm (~ 3.1 eV). The corresponding luminescence\ncenter is based on a defect containing aluminum and alkali as compensators in\nnatural and synthetic quartz crystals. Photoluminescence can be detected at\nhigh temperatures above 700 K. The thermal quenching activation energy is 0.15\neV and the frequency factor is 3 10$^7$ s$^{-1}$. In the samples with silver\nions the main luminescence band is located at ~ 260 nm (~ 4.7 eV) with a time\nconstant of ~ 37 $\\mu$s at 80 K, and in the samples with copper ions the PL\nband is at ~ 360 nm (~ 3.4 eV) with a time constant ~ 50 {\\mu}s at 80 K. For\nluminescence associated with silver the energy of thermal quenching is 0.7 eV\nwith a frequency coefficient of 1 10$^{14}$ s$^{-1}$, and for the luminescence\nrelated to copper, these parameters are 0.55 eV and 10$^{14}$ s$^{-1}$. The\ndifferences in intra-center luminescence properties of the same defect\ncontaining alkali ions or noble ions are based on differences in electronic\ntransitions. In the case of alkali ions the charge transfer transitions between\noxygen and alkali ions. In the case of noble ions absorption-luminescence\ncorresponds to intra ion transitions. Radiation properties are related to\ntrapping of an electron on one valence ion. Created atom moves out of aluminum\ncontaining defect. The hole remains on aluminum-oxygen defect. Thermally\nstimulated luminescence is related to release of atom, it diffusion to aluminum\ndefect with the hole on oxygen and following radiative recombination."
    },
    {
        "anchor": "Quantum dynamics of wave packets in a nonstationary parabolic potential\n  and the Kramers escape rate theory: At sufficiently low temperatures, the reaction rates in solids are controlled\nby quantum rather than by thermal fluctuations. We solve the Schr\\\"odinger\nequation for a Gaussian wave packet in a nonstation-ary harmonic oscillator and\nderive simple analytical expressions for the increase of its mean energy with\ntime induced by the time-periodic modulation. Applying these expressions to the\nmodified Kra-mers theory, we demonstrate a strong increase of the rate of\nescape out of a potential well under the time-periodic driving, when the\ndriving frequency of the well position equals its eigenfrequency, or when the\ndriving frequency of the well width exceeds its eigenfrequency by a factor of\n~2. Such re-gimes can be realized near localized anharmonic vibrations (LAVs),\nin which the amplitude of atomic oscillations greatly exceeds that of harmonic\noscillations (phonons) that determine the system tem-perature. LAVs can be\nexcited either thermally or by external triggering, which can result in strong\ncatalytic effects due to amplification of the Kramers rate",
        "positive": "Vibrations and tunneling of strained nanoribbons at finite temperature: Crystalline sheets (e.g., graphene and transition metal dichalcogenides)\nliberated from a substrate are a paradigm for materials at criticality because\nflexural phonons can fluctuate into the third dimension. Although studies of\nstatic critical behaviors (e.g., the scale-dependent elastic constants) are\nplentiful, investigations of dynamics remain limited. Here, we use molecular\ndynamics to study the time dependence of the midpoint (the height\ncenter-of-mass) of doubly clamped nanoribbons, as prototypical graphene\nresonators, under a wide range of temperature and strain conditions. By\ntreating the ribbon midpoint as a Brownian particle confined to a nonlinear\npotential (which assumes a double-well shape beyond the buckling transition),\nwe formulate an effective theory describing the ribbon's tunneling rate across\nthe two wells and its oscillations inside a given well. We find that, for\nnanoribbbons compressed above the Euler buckling point and thermalized above a\ntemperature at which the non-linear effects due to thermal fluctuations become\nsignificant, the exponential term (the ratio between energy barrier and\ntemperature) depends only on the geometry, but not the temperature, unlike the\nusual Arrhenius behavior. Moreover, we find that the natural oscillation time\nfor small strain shows a non-trivial scaling $\\tau_{\\rm o}\\sim\nL_0^{\\,z}T^{-\\eta/4}$, with $L_0$ being the ribbon length, $z=2-\\eta/2$ being\nthe dynamic critical exponent, $\\eta=0.8$ being the scaling exponent describing\nscale-dependent elastic constants, and $T$ being the temperature. These unusual\nscale- and temperature-dependent dynamics thus exhibit dynamic criticality and\ncould be exploited in the development of graphene-based nanoactuators."
    },
    {
        "anchor": "Meso-scale approach to modelling the fracture process zone of concrete\n  subjected to uniaxial tension: A meso-scale analysis is performed to determine the fracture process zone of\nconcrete subjected to uniaxial tension. The meso-structure of concrete is\nidealised as stiff aggregates embedded in a soft matrix and separated by weak\ninterfaces. The mechanical response of the matrix, the inclusions and the\ninterface between the matrix and the inclusions is modelled by a discrete\nlattice approach. The inelastic response of the lattice elements is described\nby a damage approach, which corresponds to a continuous reduction of the\nstiffness of the springs. The fracture process in uniaxial tension is\napproximated by an analysis of a two-dimensional cell with periodic boundary\nconditions. The spatial distribution of dissipated energy density at the\nmeso-scale of concrete is determined. The size and shape of the deterministic\nFPZ is obtained as the average of random meso-scale analyses. Additionally,\nperiodicity of the discretisation is prescribed to avoid influences of the\nboundaries of the periodic cell on fracture patterns. The results of these\nanalyses are then used to calibrate an integral-type nonlocal model.",
        "positive": "Infrared Optical Anisotropy in Quasi-1D Hexagonal Chalcogenide BaTiSe3: Polarimetric infrared detection bolsters IR thermography by leveraging the\npolarization of light. Optical anisotropy, i.e., birefringence and dichroism,\ncan be leveraged to achieve polarimetric detection. Recently, giant optical\nanisotropy was discovered in quasi-1D narrow-bandgap hexagonal perovskite\nsulfides, A1+xTiS3, specifically BaTiS3[1,2] and Sr9/8TiS3[3,4]. In these\nmaterials, the critical role of atomic-scale structure modulations[4,5] in the\nunconventional electrical[5,6], optical[7,8], and thermal[7,9] properties\nraises the broader question of other materials that belong to this family. To\naddress this issue, for the first time, we synthesized high-quality single\ncrystals of a largely unexplored member of the A1+xTiX3 (X = S, Se) family,\nBaTiSe3. Single-crystal X-ray diffraction determined the room-temperature\nstructure with the P31c space group, which is a superstructure of the earlier\nreported[10] P63/mmc structure. The crystal structure of BaTiSe3 features\nantiparallel c-axis displacements similar to BaTiS3,[2] but is of lower\nsymmetry. Polarization-resolved Raman and Fourier transform infrared (FTIR)\nspectroscopy were used to characterize the optical anisotropy of BaTiSe3, whose\nrefractive index along the ordinary (perpendicular to c) and extraordinary\n(parallel to c) optical axes was quantitatively determined by combining\nellipsometry studies with FTIR. With a giant birefringence {\\Delta}n~0.9,\nBaTiSe3 emerges as a new candidate for miniaturized birefringent optics for\nmid-wave infrared to long-wave infrared imaging."
    },
    {
        "anchor": "Electronic Properties of MoS2/HfO2 Interface: Impact of Interfacial\n  Impurities during Atomic Layer Deposition Growth: Using ab-initio calculations within the framework of Density Functional\nTheory (DFT), atomic structures and electronic properties of MoS2/HfO2\ninterface are investigated. The impact of interfacial oxygen concentration on\nthe MoS2/HfO2 interface electronic structure is examined in order to mimic the\natomic layer deposition growth at ambient conditions. Then, the effect on band\noffsets and the thermodynamic stability of those interfaces is investigated and\ncompared with available relevant experimental data. These results seem to\nindicate that, for a well-prepared interface, the electronic device performance\nshould be better than other interfaces like III-V/high-k due to the absence of\ninterface defect states. However, any unpassivated defects, if present during\noxide growth, strongly influence the subsequent electronic properties of the\ninterface.",
        "positive": "Dynamics of Charge Flow in the Channel of a Thin-Film Field-Effect\n  Transistor: The local conductivity in the channel of a thin-film field-effect transistor\nis proportional to the charge density induced by the local gate voltage. We\nshow how this determines the frequency- and position-dependence of the charge\ninduced in the channel for the case of \"zero applied current\": zero\ndrain-source voltage with charge induced by a square-wave voltage applied to\nthe gate, assuming constant mobility and negligible contact impedances. An\napproximate expression for the frequency dependence of the induced charge in\nthe center of the channel can be conveniently used to determine the charge\nmobility. Fits of electro-optic measurements of the induced charge in organic\ntransistors are used as examples."
    },
    {
        "anchor": "Trail-Needs pseudopotentials in quantum Monte Carlo calculations with\n  plane-wave/blip basis sets: We report a systematic analysis of the performance of a widely used set of\nDirac-Fock pseudopotentials for quantum Monte Carlo (QMC) calculations. We\nstudy each atom in the periodic table from hydrogen (Z=1) to mercury (Z=80),\nwith the exception of the 4f elements (57 <= Z <= 70). We demonstrate that\nghost states are a potentially serious problem when plane-wave basis sets are\nused in density functional theory (DFT) orbital-generation calculations, but\nthat this problem can be almost entirely eliminated by choosing the s channel\nto be local in the DFT calculation; the d channel can then be chosen to be\nlocal in subsequent QMC calculations, which generally leads to more accurate\nresults. We investigate the achievable energy variance per electron with\ndifferent levels of trial wave function and we determine appropriate plane-wave\ncutoff energies for DFT calculations for each pseudopotential. We demonstrate\nthat the so-called \"T-move\" scheme in diffusion Monte Carlo is essential for\nmany elements. We investigate the optimal choice of spherical integration rule\nfor pseudopotential projectors in QMC calculations. The information reported\nhere will prove crucial in the planning and execution of QMC projects involving\nbeyond-first-row elements.",
        "positive": "Ion-beam sculpting of nanowires: Nanomaterials often undergo unusual mechanical deformations compared to their\nbulk counterparts when irradiated with ion-beams. This study visualizes and\ninvestigates some of the unusual interactions that can occur in nanomaterials\nduring irradiation with medium-energy ion-beams using a Helium-Ion-Microscope\n(HIM). Ion-beam sculpting of semiconductor nanowires (NWs) with sub-10 nm\nfeatures is demonstrated. Moreover, irradiation-induced growth of NWs at\nroom-temperature is discovered. The new concept and possible mechanism of\nirradiation-induced VLS (vapor-liquid-solid) growth of NWs is introduced. These\nresults are the basis for further fundamental and technological developments\ntowards manipulation and visualization of ion-matter interactions at\nnanoscales."
    },
    {
        "anchor": "Diffuse-interface model for nanopatterning induced by self-sustained ion\n  etch masking: We construct a simple phenomenological diffuse-interface model for\ncomposition-induced nanopatterning during ion sputtering of alloys. In\nsimulations, this model reproduces without difficulties the high-aspect ratio\nstructures and tilted pillars observed in experiments. We investigate the time\nevolution of the pillar height, both by simulations and by {\\it in situ}\nellipsometry. The analysis of the simulation results yields a good\nunderstanding of the transitions between different growth regimes and supports\nthe role of segregation in the pattern-formation process.",
        "positive": "Electronic correlation in nanoscale junctions: Comparison of the GW\n  approximation to a numerically exact solution of the single-impurity Anderson\n  model: The impact of electronic correlation in nanoscale junctions, e.g. formed by\nsingle molecules, is analyzed using the single-impurity Anderson model.\nNumerically exact Quantum Monte Carlo calculations are performed to map out the\norbital filling, linear response conductance and spectral function as a\nfunction of the Coulomb interaction strength and the impurity level position.\nThese numerical results form a benchmark against which approximate, but more\nbroadly applicable, approaches to include electronic correlation in transport\ncan be compared. As an example, the self consistent GW approximation has been\nimplemented for the Anderson model and the results compared to this benchmark.\nFor weak coupling or for level positions such that the impurity is either\nnearly empty or nearly full, the GW approximation is found to be accurate.\nHowever, for intermediate or strong coupling, the GW approximation does not\nproperly represent the impact of spin or charge fluctuations. Neither the\nspectral function nor the linear response conductance are accurately given\nacross the Coulomb blockade plateau and well into the mixed valence regimes."
    },
    {
        "anchor": "Surface terraces in pure tungsten formed by high-temperature oxidation: We observe large-scale surface terraces in tungsten oxidised at high\ntemperature and in high vacuum. Their formation is highly dependent on crystal\norientation, with only {111} grains showing prominent terraces. Terrace facets\nare aligned with {100} crystallographic planes, leading to an increase in total\nsurface energy, making a diffusion-driven formation mechanism unlikely. Instead\nwe hypothesize that preferential oxidation of {100} crystal planes controls\nterrace formation. Grain height profiles after oxidation and the morphology of\nsamples heat treated with limited oxygen supply are consistent with this\nhypothesis. Our observations have important implications for the use of\ntungsten in extreme environments.",
        "positive": "Dressed excitonic states and quantum interference in a three-level\n  quantum dot ladder system: We observe dressed states and quantum interference effects in a strongly\ndriven three-level quantum dot ladder system. The effect of a strong coupling\nfield on one dipole transition is measured by a weak probe field on the second\ndipole transition using differential reflection. When the coupling energy is\nmuch larger than both the homoge-neous and inhomogeneous linewidths an\nAutler-Townes splitting is observed. Striking differences are observed when the\ntransitions resonant with the strong and weak fields are swapped, particularly\nwhen the coupling energy is nearly equal to the measured linewidth. This result\nis attributed to quantum interference: a modest destructive or constructive\ninterference is observed depending on the pump / probe geometry. The data\ndemonstrate that coher-ence of both the bi-exciton and the exciton is\nmaintained in this solid-state system, even under intense illumina-tion, which\nis crucial for prospects in quantum information processing and non-linear\noptical devices."
    },
    {
        "anchor": "Importance of glassy fragility for energy applications of ionic liquids: Ionic liquids (ILs) are salts that are liquid close to room temperature.\nTheir possible applications are numerous, e.g., as solvents for green chemistry\nin various electrochemical devices, and even for such \"exotic\" purposes as\nspinning-liquid mirrors for lunar telescopes. Here we concentrate on their use\nfor new advancements in energy-storage and -conversion devices: Batteries,\nsupercapacitors or fuel cells using ILs as electrolytes could be important\nbuilding blocks for the sustainable energy supply of tomorrow. Interestingly,\nILs show glassy freezing and the universal, but until now only poorly\nunderstood dynamic properties of glassy matter, dominate many of their physical\nproperties. We show that the conductivity of ILs, an essential figure of merit\nfor any electrochemical application, depends in a systematic way not only on\ntheir glass temperature but also on the so-called fragility, characterizing the\nnon-canonical super-Arrhenius temperature dependence of their ionic mobility.",
        "positive": "Link between Weyl-fermion chirality and spin texture: Topological semimetals have recently attracted great attention due to\nprospective applications governed by their peculiar Fermi surfaces. Weyl\nsemimetals host chiral fermions that manifest as pairs of non-degenerate\nmassless Weyl points in their electronic structure, giving rise to novel\nmacroscopic quantum phenomena such as the chiral anomaly, an unusual\nmagnetoresistance, and various kinds of Hall effects These properties enable\nthe engineering of non-local electric transport devices, magnetic sensors and\nmemories, and spintronics devices. Nevertheless, little is known about the\nunderlying spin- and orbital-degrees of freedom of the electron wave functions\nin Weyl semimetals, that govern the electric transport. Here, we give evidence\nthat the chirality of the Weyl points in the Type-II Weyl semimetal MoTe$_2$ is\ndirectly linked to the spin texture and orbital angular momentum of the\nelectron wave functions. By means of state-of-the-art spin- and\nmomentum-resolved photoemission spectroscopy the spin- and orbital texture in\nthe Fermi surface is directly resolved. Supported by first-principles\ncalculations, we examined the relationship between the topological chiral\ncharge and spin texture, which significantly contributes to the understanding\nof the electronic structure in topological quantum materials."
    },
    {
        "anchor": "Adsorption properties and third sound propagation in superfluid $^4$He\n  films on carbon nanotubes: We consider the adsorption properties of superfluid $^4$He films on carbon\nnanotubes. One major factor in the adsorption is the surface tension force\narising from the very small diameter of the nanotubes. Calculations show that\nsurface tension keeps the film thickness on the tubes very thin even when the\nhelium vapor is increased to the saturated pressure. The weakened Van der Waals\nforce due to the cylindrical geometry also contributes to this. Both of these\neffects act to lower the predicted velocity of third sound propagation along\nthe tubes. It does not appear that superfluidity will be possible on\nsingle-walled nanotubes of diameter about one nm, since the film thickness is\nless than 3 atomic layers even at saturation. Superfluidity is possible on\nlarger-diameter nanotube bundles and multi-walled nanotubes, however. We have\nobserved third sound signals on nanotube bundles of average diameter 5 nm which\nare sprayed onto a Plexiglass surface, forming a network of tubes.",
        "positive": "Formation of Microcrystalline Structure in Large-Scale Ingots of Ti\n  Alloy Ti-6Al-4V during the Complex Loading: A new method of combined loading was developed for manufacturing large -\nscale ingot of alpha-beta titanium alloy Ti-6Al-4V with the diameter of the\ngauge 120 mm and the length 300 mm. The process includes torsion with\nsimultaneous tensile deformation, followed by a single compression and drawing\nof the ingot in alpha-beta temperature phase fields. Ingot structure and\nmechanical property evaluation was performed after deformation and\npost-deformation heating. The ingots had completely homogeneous macrostructure.\nThe ingot microstructures were alpha plus beta with a mean grain size of d=10\nm. There has not been any significant difference in microstructure of central\nand periphery areas in the cross section of the ingot."
    },
    {
        "anchor": "Theory of Orbital Susceptibility in the Tight-Binding Model: Corrections\n  to the Peierls Phase: An extended formula for orbital susceptibility including corrections of the\nPeierls phase is introduced. By using the new developed formula, the orbital\nsusceptibility of benzene is estimated analytically on the basis of the $\\pi$\nelectron approximation. As a result, it is found that the orbital\nsusceptibility is 1.2 times larger than that estimated only from the Peierls\nphase. The Coulomb interaction dependence of the orbital susceptibility of\nbenzene is also discussed by using exact diagonalization. It is found that the\nabsolute value of the orbital susceptibility decreases as the Coulomb\ninteraction increases, while the ratio of the orbital susceptibility with and\nwithout the corrections of the Peierls phase increases. Finally, we discuss the\norbital susceptibility of a single-band tight-binding model on a square\nlattice. We clarify that the correction of the Peierls phase is comparable to\nthe Landau--Peierls orbital susceptibility and that it corresponds to the Fermi\nsea term.",
        "positive": "Current-induced magnetization switching in MgO barrier based magnetic\n  tunnel junctions with CoFeB/Ru/CoFeB synthetic ferrimagnetic free layer: We report the intrinsic critical current density (Jc0) in current-induced\nmagnetization switching and the thermal stability factor (E/kBT, where E, kB,\nand T are the energy potential, the Boltzmann constant, and temperature,\nrespectively) in MgO based magnetic tunnel junctions with a\nCo40Fe40B20(2nm)/Ru(0.7-2.4nm)/Co40Fe40B20(2nm) synthetic ferrimagnetic (SyF)\nfree layer. We show that Jc0 and E/kBT can be determined by analyzing the\naverage critical current density as a function of coercivity using the\nSlonczewski's model taking into account thermal fluctuation. We find that high\nantiferromagnetic coupling between the two CoFeB layers in a SyF free layer\nresults in reduced Jc0 without reducing high E/kBT."
    },
    {
        "anchor": "Interface-related magnetic and vibrational properties in Fe/MgO\n  heterostructures from nuclear resonant spectroscopy and first-principles\n  calculations: We combine $^{57}$Fe M\\\"ossbauer spectroscopy and $^{57}$Fe nuclear resonant\ninelastic x-ray scattering (NRIXS) in nanoscale polycrystalline\n[bcc-$^{57}$Fe/MgO] multilayers with various Fe layer thicknesses and\nlayer-resolved density-functional-theory (DFT) based first-principles\ncalculations of a (001)-oriented [Fe(8 ML)/MgO(8 ML)](001) heterostructure to\nunravel the interface-related atomic vibrational properties of a multilayer\nsystem. In theory and experiment, we observe consistently enhanced hyperfine\nmagnetic fields compared to bulk which are associated with the Fe/MgO interface\nlayers. NRIXS and DFT both reveal a strong reduction of the longitudinal\nacoustic (LA) phonon peak in combination with an enhancement of the low-energy\nvibrational density of states (VDOS) suggesting that the presence of interfaces\nand the associated increase in the layer-resolved magnetic moments results in\ndrastic changes in the Fe-partial VDOS. From the experimental and calculated\nVDOS, vibrational thermodynamic properties have been determined as a function\nof Fe thickness and are found to be in excellent agreement.",
        "positive": "Single ice crystal growth with controlled orientation during directional\n  freezing: Ice growth has attracted great attention for its capability of fabricating\nhierarchically porous microstructure. However, the formation of tilted lamellar\nmicrostructure during freezing needs to be reconsidered due to the limited\ncontrol of ice orientation with respect to thermal gradient during in-situ\nobservations, which can greatly enrich our insight into architectural control\nof porous biomaterials. This paper provides an in-situ study of solid/liquid\ninterface morphology evolution of directionally solidified single crystal ice\nwith its C-axis (optical axis) perpendicular to directions of both thermal\ngradient and incident light in poly (vinyl alcohol, PVA) solutions. Misty\nmorphology and V-shaped lamellar morphology were clearly observed in-situ for\nthe first time. Quantitative characterizations on lamellar spacing, tilt angle\nand tip undercooling of lamellar ice platelets provide a clearer insight into\nthe inherent ice growth habit in polymeric aqueous systems and are suggested\nexert significant impact on future design and optimization in porous\nbiomaterials."
    },
    {
        "anchor": "InGaN/GaN Tunnel Junctions For Hole Injection in GaN Light Emitting\n  Diodes: InGaN/GaN tunnel junction contacts were grown on top of an InGaN/GaN blue\n(450 nm) light emitting diode wafer using plasma assisted molecular beam\nepitaxy. The tunnel junction contacts enable low spreading resistance n-GaN top\ncontact layer thereby requiring less top metal contact coverage on the surface.\nA voltage drop of 5.3 V at 100 mA, forward resistance of 2 x 10-2 ohm cm2 and a\nhigher light output power are measured in tunnel junction LED. A low resistance\nof 5 x 10-4 ohm cm2 was measured in a MBE grown tunnel junction on GaN PN\njunction device, indicating that the tunnel junction LED device resistance is\nlimited by the regrowth interface and not by the intrinsic tunneling\nresistance.",
        "positive": "Effect of shear strain on band structure and electronic properties of\n  phosphorene: We present an ab-initio investigation of effects of shear strain on band\nstructure and electronic properties of 2D phosphorene. We carried out DFT\ncalculations to determine the shear stress as a function of shear strain and\nfound the monolayer phosphorene has ultimate strength at shear strain 30% and\n35% in armchair and zigzag directions, respectively, and it was also found that\nthe monolayer extends in z direction on applying shear strain in both\ndirections. Additionally, we derived band structures of phosphorene along both\ndirections under shear strain and have shown that band gap in phosphorene\ndecreases along both directions and that phosphorene shows a semi-metal nature\non applying shear strain of magnitude 30% in both directions. The electrical\nconductivity of phosphorene was estimated by effective mass along zigzag and\narmchair directions and it is shown that the electrical conductivity is far\nhigher along armchair direction, and that with increasing shear strain\nconductivity increases along armchair, up to ultimate strength, and zigzag\ndirections."
    },
    {
        "anchor": "Coupled dynamics of electrons and phonons in metallic nanotubes: current\n  saturation from hot phonons generation: We show that the self-consistent dynamics of both phonons and electrons is\nthe necessary ingredient for the reliable description of the hot phonons\ngeneration during electron transport in metallic single-wall carbon nanotubes\n(SWNTs). We solve the coupled Boltzmann transport equations to determine in a\nconsistent way the current vs. voltage (IV) curve and the phonon occupation in\nmetallic SWNTs which are lying on a substrate. We find a good agreement with\nmeasured IV curves and we determine an optical phonon occupation which\ncorresponds to an effective temperature of several thousands K (hot phonons),\nfor the voltages typically used in experiments. We show that the high-bias\nresistivity strongly depends on the optical phonon thermalization time. This\nimplies that a drastic improvement of metallic nanotubes performances can be\nachieved by increasing the coupling of the optical phonons with a\nthermalization source.",
        "positive": "Reversal of coupled vortices in advanced spintronics: A mechanistic\n  study: This study conducts a comprehensive investigation into the reversal mechanism\nof magnetic vortex cores in a nanopillar system composed of two coupled\nferromagnetic dots under zero magnetic field conditions. The research employs a\ncombination of experimental and simulation methods to gain a deeper\nunderstanding of the dynamics of magnetic vortex cores. The findings reveal\nthat by applying a constant direct current, the orientation of the vortex cores\ncan be manipulated, resulting in a switch in one of the dots at a specific\ncurrent value. The micromagnetic simulations provide evidence that this switch\nis a consequence of a deformation in the vortex profile caused by the\nincreasing velocity of the vortex cores resulting from the constant amplitude\nof the trajectory as frequency increases. These findings offer valuable new\ninsights into the coupled dynamics of magnetic vortex cores and demonstrate the\nfeasibility of manipulating their orientation using direct currents under zero\nmagnetic field conditions. The results of this study have potential\nimplications for the development of vortex-based non-volatile memory\ntechnologies. \\end{abstract}"
    },
    {
        "anchor": "Solitonic Phase in Manganites: Whenever a symmetry in the ground state of a system is broken, topological\ndefects will exist. These defects are essential for understanding phase\ntransitions in low dimensional systems[1]. Excitingly in some unique condensed\nmatter systems the defects are also the low energy electric charge excitations.\nThis is the case of skyrmions in quantum Hall ferromagnets[2] and solitons in\npolymers[3]. Orbital order present in several transitions metal compounds[4-6]\ncould give rise to topological defects. Here we argue that the topological\ndefects in orbital ordered half doped manganites are orbital solitons.\nSurprisingly, these solitons carry a fractional charge of $\\pm$e/2, and\nwhenever extra charge is added to the system an array of solitons is formed and\nan incommensurate solitonic phase occurs. The striking experimental asymmetry\nin the phase diagram as electrons or holes are added to half doped\nmanganites[7-12], is explained by the energy difference between positive and\nnegative charged solitons. Contrary to existent models that explain coexistence\nbetween phases in manganites as an extrinsic effect[13-14], the presence of\ninhomogeneities is naturally explained by the existence of solitonic phases.\nThe occurrence and relevance of orbital solitons might be a general phenomena\nin strongly correlated systems.",
        "positive": "Active bialkali photocathodes on free-standing graphene substrates: The hexagonal structure of graphene gives rise to the property of gas\nimpermeability, motivating its investigation for a new application: protection\nof semiconductor photocathodes in electron accelerators. These materials are\nextremely susceptible to degradation in efficiency through multiple mechanisms\nrelated to contamination from the local imperfect vacuum environment of the\nhost photoinjector. Few-layer graphene has been predicted to permit a modified\nphotoemission response of protected photocathode surfaces, and recent\nexperiments of single-layer graphene on copper have begun to confirm these\npredictions for single crystal metallic photocathodes. Unlike metallic\nphotoemitters, the integration of an ultra-thin graphene barrier film with\nconventional semiconductor photocathode growth processes is not\nstraightforward. A first step toward addressing this challenge is the growth\nand characterization of technologically relevant, high quantum efficiency\nbialkali photocathodes grown on ultra-thin free-standing graphene substrates.\nPhotocathode growth on free-standing graphene provides the opportunity to\nintegrate these two materials and study their interaction. Specifically,\nspectral response features and photoemission stability of cathodes grown on\ngraphene substrates are compared to those deposited on established substrates.\nIn addition we observed an increase of work function for the graphene\nencapsulated bialkali photocathode surfaces, which is predicted by our\ncalculations. The results provide a unique demonstration of bialkali\nphotocathodes on free-standing substrates, and indicate promise towards our\ngoal of fabricating high-performance graphene encapsulated photocathodes with\nenhanced lifetime for accelerator applications."
    },
    {
        "anchor": "Toward the Identification of Atomic Defects in Hexagonal Boron Nitride:\n  X-Ray Photoelectron Spectroscopy and First-Principles Calculations: Defects in hexagonal boron nitride (hBN) exhibit single-photon emission (SPE)\nand are thus attracting broad interest as platforms for quantum information and\nspintronic applications. However, the atomic structure and the specific impact\nof the local environment on the defect physical properties remain elusive. Here\nwe articulate X-ray photoelectron spectroscopy (XPS) and first-principles\ncalculations to discern the experimentally-observed point defects responsible\nfor the quantum emission observed in hBN. XPS measurements show a broad band,\nwhich was deconvolved and then assigned to $N_{B}V_{N}$, $V_{N}$, $C_{B}$,\n$C_{B}V_{N}$, and $O_{2B}V_{N}$ defect structures using Density Functional\nTheory (DFT) core-level binding energy (BE) calculations.",
        "positive": "Loss of anisotropy in strained ultrathin epitaxial L10 Mn-Ga films: In this work we are investigating the effect of strain in ultrathin Mn-Ga\nthin films on the magnetic properties at room temperature. Two different Mn-Ga\ncompositions of which one is furthermore doped with Co were grown on Cr\nbuffered MgO (001) substrates. Films with a thickness below 12nm are highly\nstrained and it was observed that the ratio c/a vs. thickness is depending on\ncomposition. Using c/a as an order parameter the PMA is shown to be drastically\nreduced with increasing strain. These findings should be considered when\ngeneralizing and downscaling results obtained from films >20nm. Furthermore it\nhas been shown, that the strain can be reduced by introducing an additional Pt\nbuffer and thus maintaining a high PMA for a thickness as low as 6nm."
    },
    {
        "anchor": "Role of Electronic Structure in the Morphotropic Phase Boundary of\n  TbxDy1-xCo2 Studied by First-principles Calculation: Physically parallel to ferroelectric morphotropic phase boundary, a phase\nboundary separating two ferromagnetic phase of different crystallographic\nsymmetries was found in TbxDy1-xCo2. High-resolution synchrotron XRD has been\ncarried out to offer experimental evidence for TbxDy1-xCo2. It has been proved\nthat TbxDy1-xCo2 (0.6<x<0.7) is a morphotropic phase boundary and that the\ncrystal structures of tetragonal (x<0.6) and rhombohedral (x>0.7) phase is\ndistorted from a Laves Phase. Here, a first principles calculation provides a\ntheoretical explanation on the origin of MBP in TbxDy1-xCo2 and is also\nprovided for the question of why MPB occurs in TbxDy1-xCo2 alloys.",
        "positive": "Spectroscopic evidence for a new type of surface resonance at noble\n  metal surfaces: We investigate the surface- and bulk-like properties of the pristine\n(110)-surface of silver using threshold photoemission by excitation with light\nof 5.9 eV. Using a momentum microscope, we identified two distinct transitions\nalong the $\\overline{\\Gamma}\\,\\overline{\\textrm{Y}}$-direction of the crystal.\nThe first one is a so far unknown surface resonance for the (110) noble metal\nsurface, exhibiting an exceptionally large bulk character, that has so far been\nelusive in surface sensitive experiments. The second one stems from the well\nknown bulk-like Mahan cone oriented along the $\\Gamma L$-direction inside the\ncrystal but projected onto the (110)-surface cut. The existence of the new\nstate is confirmed by photocurrent calculations and its character analyzed."
    },
    {
        "anchor": "Correlation-driven metal-insulator transition in unconventional magnetic\n  metal superoxides: Using first-principles electronic structure calculations, we have extensively\nstudied the electronic and magnetic properties of alkali sodium superoxide\n(NaO2) in comparison with that of potassium superoxide (KO2) both at high and\nlow temperatures. These properties of these superoxides are governed by the\nunpaired electron donated by the alkali atoms Na and K to the O atoms forming\ndimers. This unpaired electron is the source of orbital fluctuations in the\nO-{\\pi}* manifold for both cases. In order to reduce this orbital fluctuation,\nboth go through several structural phase transitions. In these plethora of\nstructures, the O2- dimers undergo rotation, leading to a complex linking of\nits orbital degrees of freedom with its spin degrees of freedom. Hence the\nmagnetic properties are found to be controlled by this unpaired electron vary\nas the orientations of these O2 - dimers change. Due to the change in the\norientations of O2- dimers, the alkali ion cages around the O2 - dimers change\nfrom square in the pyrite phase to rhombus and rectangle for the orthorhombic\nphase for NaO2 and square in the tetragonal phase to parallelogram in the\nmonoclinic phase for KO2 on the plane cutting through the dimers. The band\nstructures of NaO2 in the low-temperature orthorhombic phase and KO2 in the\nmonoclinic phase show that the lifting of degeneracy in the O-{\\pi}* manifold\nis due to the redefined electrostatic interaction between the K/Na cages and\nthe O2 - dimers. This, inaddition to electron correlation among the localized\nO-{\\pi}* electrons, establishes complete orbital ordering (OO) in turn drives\nmetal-insulator transition (MIT) in both the systems. Furthermore, K doping for\nNa in NaO2 also results in correlation-induced MIT, predicted to take place at\na temperature higher than that in NaO2. This opens up the possibility of MIT in\nRb/Cs-doped NaO2 at even higher temperatures.",
        "positive": "Electronic structure and excitations in oxygen deficient\n  CeO$_{2-\u03b4}$ from DFT calculations: The electronic structures of supercells of CeO$_{2-\\delta}$ have been\ncalculated within the Density Functional Theory (DFT). The equilibrium\nproperties such as lattice constants, bulk moduli and magnetic moments are well\nreproduced by the generalized gradient approximation (GGA). Electronic\nexcitations are simulated by robust total energy calculations for constrained\nstates with atomic core- or valence-holes. Pristine ceria CeO$_2$ is found to\nbe a non-magnetic insulator with magnetism setting in as soon as oxygens are\nremoved from the structure. In the ground state of defective ceria, the Ce-$f$\nmajority band resides near the Fermi level, but appears at about 2 eV below the\nFermi level in photoemission spectroscopy experiments due to final state\neffects. We also tested our computational method by calculating threshold\nenergies in Ce-M$_5$ and O-K x-ray absorption spectroscopy and comparing\ntheoretical predictions with the corresponding measurements. Our result that\n$f$ electrons reside near the Fermi level in the ground state of oxygen\ndeficient ceria is crucial for understanding catalytic properties of CeO$_2$\nand related materials."
    },
    {
        "anchor": "An Efficient Monte Carlo Algorithm for Determining the Minimum Energy\n  Structures of Metallic Grain Boundaries: Sampling minimum energy grain boundary (GB) structures in the\nfive-dimensional crystallographic phase space can provide much-needed insight\ninto how GB crystallography affects various interfacial properties. However,\nthe complexity and number of parameters involved often limits the extent of\nthis exploration to a small set of interfaces. In this article, we present a\nfast Monte Carlo scheme for generating zero-Kelvin, low energy GB structures in\nthe five-dimensional crystallographic phase space. The Monte Carlo trial moves\ninclude removal and insertion of atoms in the GB region, which create a diverse\nset of GB configurations and result in a rapid convergence to the low energy\nstructure. We have validated the robustness of this approach by simulating over\n1184 tilt, twist, and mixed character GBs in both fcc (Aluminum and Nickel) and\nbcc ($\\alpha$-Iron) metallic systems.",
        "positive": "Direct Observation of an Interface Dipole between Two Metallic Oxides\n  Caused by Localized Oxygen Vacancies: Oxygen vacancies are increasingly recognized to play a role in phenomena\nobserved at transition-metal oxide interfaces. Here we report a study of\nSrRuO3/La0.7Sr0.3MnO3 (SRO/LSMO) interfaces using a combination of quantitative\naberration-corrected scanning transmission electron microscopy, electron energy\nloss spectroscopy, and density-functional calculations. Cation displacements\nare observed at the interface, indicative of a dipole-like electric field even\nthough both materials are nominally metallic. The observed displacements are\nreproduced by theory if O vacancies are present in the near-interface LSMO\nlayers. The results suggest that atomic-scale structural mapping can serve as a\nquantitative indicator of the presence of O vacancies at interfaces."
    },
    {
        "anchor": "One dimensional zone center phonons in $O_{h}$ space group: Motivated by experiments, we performed a systematic study on the one\ndimensional zone center phonons in $O_{h}$ space groups. All the one\ndimensional phonon modes for different Wyckoff positions are tabulated. We show\nthat at least four (inequivalent) atoms (in one set of Wyckoff positions) are\nneeded to carry a single one dimensional phonon. A general restriction rule on\nthe number of atoms and the number of one dimensional phonons is obtained. The\nsame restriction applies to phonons of all cubic crystal systems ($T$, $T_{h}$,\n$T_{d}$, $O$, $O_{h}$) and to magnons for crystals whose unitary symmetry\nelements are in ($T$, $T_{h}$, $T_{d}$, $O$, $O_{h}$). Crystals with $A15$\nstructure are found to satisfy experimental requirements (to have a\n$\\Gamma_{2}^{+}$ phonon) while most crystals of $O_{h}$ space groups do not.\n$A15$ is also used to demonstrate the rules we found regarding the phonon\nstructure in $O_{h}$ space groups.",
        "positive": "Transport properties of dipole skyrmions in amorphous FeGd multilayers: The transport response of dipole skyrmions in amorphous centrosymmetric Fe/Gd\nmultilayer is investigated by temperature and field-dependent resistivity\nmeasurements collected in three current and magnetic field configurations. It\nis shown that a dipole skyrmion lattice phase may form at certain temperatures\nleading to a unique signature of the polar longitudinal resistivity. This\nsignature differs from the conventional field-varying parabolic response\nassociated with stripe phases, which transition to a disordered skyrmion phase\nunder applied fields. Transport measurements under different field history\nprotocols reveal that the anomaly in the polar longitudinal resistivity appears\nunder specific field history reversal processes. Our experimental results are\nreproduced using micromagnetic simulations that show the anomaly in the polar\nlongitudinal resistivity is related to a domain wall reconfiguration that\noccurs as the domain morphology transitions from disordered stripes to a\nskyrmion lattice under applied perpendicular fields."
    },
    {
        "anchor": "Electrochemical investigation of MoSeTe as an anode for sodium-ion\n  batteries: Sodium ion batteries (SIBs) are considered as an efficient alternative for\nlithium-ion batteries (LIBs) owing to the natural abundance and low cost of\nsodium than lithium. In this context, the anode materials play a vital role in\nrechargeable batteries to acquire high energy and power density. In order to\ndemonstrate transition metal dichalcogenide (TMD) as potential anode materials,\nwe have synthesized MoSeTe sample by conventional flux method, and the\nstructure and morphology are characterized using x-ray diffraction (XRD),\nfield-emission scanning electron microscopy (FESEM), transmission electron\nmicroscopy (TEM), and Raman spectroscopy. These characterisations confirm the\nhexagonal crystal symmetry with p63/mmc space group and layered morphology of\nMoSeTe. We investigate the electrochemical performance of a MoSeTe as a\nnegative electrode (anode) for SIBs in the working potential range of 0.01 to\n3.0~V. In a half-cell configuration, the MoSeTe as an anode and Na metal as\ncounter/reference electrode exhibits significant initial specific discharge\ncapacities of around 475 and 355 mAhg$^{-1}$ at current densities of 50 and 100\nmAg$^{-1}$, respectively. However, the capacity degraded significantly like\n$\\approx$200~mAhg$^{-1}$ in 2nd cycle, but having $\\approx$100\\% Coulombic\nefficiency, which suggest for further modification in this material to improve\nits stability. The cyclic voltammetry (CV) study reveals the reversibility of\nthe material after 1st cycle, resulting no change in the initial peak\npositions. The electrochemical impedance spectroscopy (EIS) measurements\naffirms the smaller charge transfer resistance of fresh cells than the cells\nafter 10th cycle. Moreover, the extracted diffusion coefficient is found to be\nof the order of 10$^{-14}$ cm$^2$s$^{-1}$.",
        "positive": "The momentum and photon energy dependence of the circular dichroic\n  photoemission in the bulk Rashba semiconductors BiTeX (X = I, Br, Cl): Bulk Rashba systems BiTeX (X = I, Br, Cl) are emerging as important\ncandidates for developing spintronics devices, because of the coexistence of\nspin-split bulk and surface states, along with the ambipolar character of the\nsurface charge carriers. The need of studying the spin texture of strongly\nspin-orbit coupled materials has recently promoted circular dichroic Angular\nResolved Photoelectron Spectroscopy (cd-ARPES) as an indirect tool to measure\nthe spin and the angular degrees of freedom. Here we report a detailed photon\nenergy dependent study of the cd-ARPES spectra in BiTeX (X = I, Br and Cl). Our\nwork reveals a large variation of the magnitude and sign of the dichroism.\nInterestingly, we find that the dichroic signal modulates differently for the\nthree compounds and for the different spin-split states. These findings show a\nmomentum and photon energy dependence for the cd-ARPES signals in the bulk\nRashba semiconductor BiTeX (X = I, Br, Cl). Finally, the outcome of our\nexperiment indicates the important relation between the modulation of the\ndichroism and the phase differences between the wave-functions involved in the\nphotoemission process. This phase difference can be due to initial or final\nstate effects. In the former case the phase difference results in possible\ninterference effects among the photo-electrons emitted from different atomic\nlayers and characterized by entangled spin-orbital polarized bands. In the\nlatter case the phase difference results from the relative phases of the\nexpansion of the final state in different outgoing partial waves."
    },
    {
        "anchor": "First-principles structure search for the stable isomers of\n  stoichiometric WS2 nano-clusters: In this paper, we employ evolutionary algorithm along with the full-potential\ndensity functional theory (DFT) computations to perform a comprehensive search\nfor the stable structures of stoichiometric (WS2)n nano-clusters (n=1-9),\nwithin three different exchange-correlation functionals. Our results suggest\nthat n=3, 5, 8 are possible candidates for the low temperature magic sizes of\nWS2 nano-clusters while at temperatures above 600 Kelvin, n=5 and 7 exhibit\nhigher relative stability among the studied systems. The electronic properties\nand energy gap of the lowest energy isomers were computed within several\nschemes, including semilocal PBE and BLYP functionals, hybrid B3LYP functional,\nmany body based DFT+GW approach, and time dependent DFT calculations.\nVibrational spectra of the lowest lying isomers, computed by the force constant\nmethod, are used to address IR spectra and thermal free energy of the clusters.\nTime dependent density functional calculation in real time domain is applied to\ndetermine the full absorption spectra and optical gap of the lowest energy\nisomers of the WS2 nano-clusters.",
        "positive": "On the Origin of Plasticity-Induced Microstructure Change under Sliding\n  Contacts: Discrete dislocation plasticity (DDP) calculations are carried out to\ninvestigate the response of a single crystal contacted by a rigid sinusoidal\nasperity under sliding loading conditions to look for causes of microstructure\nchange in the dislocation structure. The mechanistic driver is identified as\nthe development of lattice rotations and stored energy in the subsurface, which\ncan be quantitatively correlated to recent tribological experimental\nobservations. Maps of surface slip initiation and substrate permanent\ndeformation obtained from DDP calculations for varying contact size and normal\nload suggest ways of optimally tailoring the interface and microstructural\nmaterial properties for various frictional loads."
    },
    {
        "anchor": "Large thermoelectric power factors in black phosphorus and phosphorene: The electronic properties of the layered black phosphorus (black-P) and its\nmonolayer counterpart phosphorene are investigated by using the\nfirst-principles calculations based on the density functional theory (DFT). The\nroom-temperature electronic transport coefficients are evaluated within the\nsemi-classical Boltzmann theory. The electrical conductivity exhibits\nanisotropic behavior while the Seebeck coefficient is almost isotropic. At the\noptimal doping level and room temperature, bulk black-P and phosphorene are\nfound to have large thermoelectric power factors of 118.4 and 138.9\n{\\mu}Wcm-1K-2, respectively. The maximum dimensionless figure of merit (ZT\nvalue) of 0.22 can be achieved in bulk black-P by appropriate n-type doping,\nprimarily limited by the reducible lattice thermal conductivity. For the\nphosphorene, the ZT value can reach 0.30 conservatively estimated by using the\nbulk lattice thermal conductivity. Our results suggest that both bulk black-P\nand phosphorene are potentially promising thermoelectric materials.",
        "positive": "Technique for the Dry Transfer of Epitaxial Graphene onto Arbitrary\n  Substrates: In order to make graphene technologically viable, the transfer of graphene\nfilms to substrates appropriate for specific applications is required. We\ndemonstrate the dry transfer of epitaxial graphene (EG) from the C-face of\n4H-SiC onto SiO2, GaN and Al2O3 substrates using a thermal release tape. We\nfurther report on the impact of this process on the electrical properties of\nthe EG films. This process enables EG films to be used in flexible electronic\ndevices or as optically transparent contacts."
    },
    {
        "anchor": "Spatial aspects of spin polarization of structurally split surface\n  states in thin films with magnetic exchange and spin-orbit interaction: A theoretical study is presented of the effect of an in-plane magnetic\nexchange field on the band structure of centrosymmetric films of noble metals\nand topological insulators. Based on an ab initio relativistic\n$\\mathbf{k}\\cdot\\mathbf{p}$ theory, a minimal effective model is developed that\ndescribes two coupled copies of a Rashba or Dirac electronic system residing at\nthe opposite surfaces of the film. The coupling leads to a structural gap at\n$\\bar{\\Gamma}$ and causes an exotic redistribution of the spin density in the\nfilm when the exchange field is introduced. We apply the model to a\nnineteen-layer Au(111) film and to a five-quintuple-layer Sb$_2$Te$_3$ film. We\ndemonstrate that at each film surface the exchange field induces spectrum\ndistortions similar to those known for Rashba or Dirac surface states with an\nimportant difference due to the coupling: At some energies, one branch of the\nstate loses its counterpart with the oppositely directed group velocity. This\nsuggests that a large-angle electron scattering between the film surfaces\nthrough the interior of the film is dominant or even the only possible for such\nenergies. The spin-density redistribution accompanying the loss of the\ncounterpart favors this scattering channel.",
        "positive": "Extraordinary Disordered Hyperuniform Multifunctional Composites: A variety of performance demands are being placed on material systems,\nincluding desirable mechanical, thermal, electrical, optical, acoustic and flow\nproperties. The purpose of the present article is to review the emerging field\nof disordered hyperuniform composites and their novel multifunctional\ncharacteristics. Disordered hyperuniform media are exotic amorphous states of\nmatter that are characterized by an anomalous suppression of large-scale\nvolume-fraction fluctuations compared to those in \"garden-variety\" disordered\nmaterials. Such unusual composites can have advantages over their periodic\ncounterparts, such as unique or nearly optimal, direction-independent physical\nproperties and robustness against defects. It will be shown that disordered\nhyperuniform composites and porous media can be endowed with a broad spectrum\nof extraordinary physical properties, including photonic, phononic, transport,\nchemical and mechanical characteristics that are only beginning to be discov"
    },
    {
        "anchor": "Sodium Pentazolate: a Nitrogen Rich High Energy Density Material: Sodium pentazolates NaN5 andNa2N5, new high energy density materials, are\ndiscovered during first principles crystal structure search for the compounds\nof varying amounts of elemental sodium and nitrogen. The pentazole anion N5- is\nstabilized in the condensed phase by sodium Na+ cations at pressures exceeding\n20 GPa, and becomes metastable upon release of pressure. The sodium azide\n(NaN3) precursor is predicted to undergo a chemical transformation above 50 GPa\ninto sodium pentazolates NaN5 and Na2N5. The calculated Raman spectrum of NaN5\nis in agreement with the experimental Raman spectrum of a previously\nunidentified substance appearing upon compression and heating of NaN3.",
        "positive": "Giant anomalous Hall and Nernst conductivities in magnetic all-$d$ metal\n  Heusler alloys: All-$d$ Heuslers are a category of novel compounds combining versatile\nfunctionalities such as caloric responses and spintronics with enhanced\nmechanical properties. Despite the promising transport properties (anomalous\nHall (AHC) and anomalous Nernst (ANC) conductivities) shown in the conventional\nCo$_2$XY Heuslers with $p$-$d$ hybridization, the all-$d$ Heuslers with only\n$d$-$d$ hybridization open a new horizon to search for new candidates with\noutstanding transport properties. In this work, we evaluate the AHC and ANC for\nthermodynamically stable ferro/ferri-magnetic all-$d$-metal regular Heusler\ncompounds based on high-throughput first-principles calculations. It is\nobserved that quite a few materials exhibit giant AHCs and ANCs, such as cubic\nRe$_2$TaMn with an AHC of 2011 S/cm, and tetragonal Pt$_2$CrRh with an AHC of\n1966 S/cm and an ANC of 7.50 A/mK. Comprehensive analysis on the electronic\nstructure reveals that the high AHC can be attributed to the occurrence of the\nWeyl nodes or gapped nodal lines in the neighbourhood of the Fermi level. The\ncorrelations between such transport properties and the number of valence\nelectrons are also thoroughly investigated, which provides a practical guidance\nto tailor AHC and ANC via chemical doping for transverse thermoelectric\napplications."
    },
    {
        "anchor": "Predicting ground-state configurations and electronic properties of the\n  thermoelectric clathrates Ba$_{8}$Al$_{x}$Si$_{46-x}$ and\n  Sr$_{8}$Al$_{x}$Si$_{46-x}$: The structural and electronic properties of the clathrate compounds\nBa$_{8}$Al$_{x}$Si$_{46-x}$ and Sr$_{8}$Al$_{x}$Si$_{46-x}$ are studied from\nfirst principles, considering an Al content $x$ between 6 and 16. Due to the\nlarge number of possible substitutional configurations we make use of a special\niterative cluster-expansion approach, to predict ground states and\nquasi-degenerate structures in a highly efficient way. These are found from a\nsimulated annealing technique where millions of configurations are sampled. For\nboth compounds, we find a linear increase of the lattice constant with the\nnumber of Al substituents, confirming experimental observations for\nBa$_{8}$Al$_{x}$Si$_{46-x}$. Also the calculated bond distances between\nhigh-symmetry sites agree well with experiment for the full compositional\nrange. For $x$ being below 16, all configurations are metallic for both\nmaterials. At the charge-balanced composition ($x=16$), the substitutional\nordering leads to a metal-semiconductor transition, and the ground states of\nBa$_{8}$Al$_{16}$Si$_{30}$ and Sr$_{8}$Al$_{16}$Si$_{30}$ exhibit indirect\nKohn-Sham band gaps of 0.36 and 0.30 eV, respectively, while configurations\nhigher in energy are metals. The finding of semiconducting behavior is a\npromising result in view of exploiting these materials in thermoelectric\napplications.",
        "positive": "Investigation of the early stage of reactive interdiffusion in the Cu-Al\n  system by in-situ transmission electron microscopy: The early stage of the reactive interdiffusion in the Cu-Al system was\ninvestigated at 350 {\\textdegree}C and 300 {\\textdegree}C thanks to in-situ\ntransmission electron microscopy. A special care was given to find conditions\nwhere the electron beam and the sample free surface do not affect significantly\nthe reaction. A special emphasis was then given on the influence of grain\nboundaries that are fast diffusion paths, and on nanoscaled particles that may\ninteract with the transformation front. It was found that there is a transient\nstate followed by a steady state where the mean growth rates of intermetallic\ncompounds follow a parabolic law indicating that the kinetics is diffusion\ncontrolled. Thanks to the in-situ observations at the nanoscale, it was also\npossible to track the local velocity of interfaces between the different\nphases. Strong fluctuations were exhibited within length scales smaller than\n100 nm and they are partly attributed to interface pinning by nanoscaled\nparticles. Last, considering thermodynamic and kinetic arguments, it is shown\nthat it is mainly an indirect effect induced by a local change of solute fluxes\nand of concentration gradients."
    },
    {
        "anchor": "Efficient and reliable method for the simulation of scanning tunneling\n  images and spectra with local basis sets: Based on Bardeen's perturbative approach to tunneling, we have found an\nexpression for the current between tip and sample, which can be efficiently\ncoded in order to perform fast ab initio simulations of STM images. Under the\nobservation that the potential between the electrodes should be nearly flat at\ntypical tunnel gaps, we have addressed the difficulty in the computation of the\ntunneling matrix elements by considering a vacuum region of constant potential\ndelimited by two surfaces (each of them close to tip and sample respectively),\nthen propagating tip and sample wave functions by means of the vacuum Green's\nfunction, to finally obtain a closed form in terms of convolutions. The current\nis then computed for every tip-sample relative position and for every bias\nvoltage in one shot. The electronic structure of tip and sample is calculated\nat the same footing, within density functional theory, and independently. This\nallows us to carry out multiple simulations for a given surface with a database\nof different tips. We have applied this method to the Si(111)-(7x7) and\nGe(111)-c(2x8) surfaces. Topographies and spectroscopic data, showing a very\ngood agreement with experiments, are presented.",
        "positive": "Tunable shear strain from resonantly driven optical phonons: Strain engineering has been extended recently to the ultrafast timescales,\ndriving metal-insulator phase transitions and the propagation of ultrasonic\ndemagnetization fronts. However, the non-linear lattice dynamics underpinning\ninterfacial optoelectronic phase switching have not yet been addressed. Here we\nfocus on the lattice dynamics initiated by impulsive resonant excitation of\npolar lattice vibrations in LaAlO$_3$ single crystals, one of the most widely\nutilized substrates for oxide electronics. We show that ionic Raman scattering\ndrives coherent oxygen octahedra rotations around a high-symmetry crystal axis\nand we identify, by means of DFT calculations, the underlying phonon-phonon\ncoupling channel. Resonant lattice excitation is shown to generate longitudinal\nand transverse acoustic wavepackets, enabled by anisotropic optically-induced\nstrain in and out of equilibrium. Importantly, shear strain wavepackets are\nfound to be generated with extraordinary efficiency at the phonon resonance,\nbeing comparable in amplitude to the more conventional longitudinal acoustic\nwaves, opening exciting perspectives for ultrafast material control."
    },
    {
        "anchor": "Crystallite-size Dependent Harmonic Magneto-electricity in SmFeO3: First- and second-harmonic dielectric susceptibilities are maidenly studied\non Samarium Orthoferrite of mesoscopic/500 nm and nanoscopic/55 nm grainsizes.\nMagneto-electrically coupled to the antiferromagnetic and spin-reorientation\ntransitions, fundamental and harmonic dielectricity consistently reflect the\nglobal/local polarization effects of crystallite-size dependent electrical\norderings. Bulk and incipient ferroelectricity respectively in nanoscopic and\nmesoscopic crystallites concur the higher-temperature antiferromagnetic\nordering (T_N ~670 K). Upon the spin-reorientation transition at\nlower-temperature (T_SR ~470 K), re-entrant relaxor state in the\nnano-crystallites and bulk-like/temperature-windowed ferroelectricity in the\nmeso-crystallites emerge. In the nano-crystallites, magneto-electric signature\nof interfacial spins' de-pinning (T_SP ~540 K) is exclusively revealed by the\nscaled-harmonics.",
        "positive": "Exciton-polaritons in cuprous oxide: Theory and comparison with\n  experiment: The observation of giant Rydberg excitons in cuprous oxide\n$\\left(\\mathrm{Cu_{2}O}\\right)$ up to a principal quantum number of $n=25$ by\nT.~Kazimierczuk \\emph{et al.} [Nature \\textbf{514}, 343, (2014)] inevitably\nraises the question whether these quasi-particles must be described within a\nmulti-polariton framework since excitons and photons are always coupled in the\nsolid. In this paper we present the theory of exciton-polaritons in\n$\\mathrm{Cu_{2}O}$. To this end we extend the Hamiltonian which includes the\ncomplete valence band structure, the exchange interaction, and the central-cell\ncorrections effects, and which has been recently deduced by F.~Schweiner\n\\emph{et al.} [Phys.~Rev.~B \\textbf{95}, 195201, (2017)], for finite values of\nthe exciton momentum $\\hbar K$. We derive formulas to calculate not only dipole\nbut also quadrupole oscillator strengths when using the complete basis of\nF.~Schweiner \\emph{et al.}. Very complex polariton spectra for the three\norientations of $\\boldsymbol{K}$ along the axes $[001]$, $[110]$, and $[111]$\nof high symmetry are obtained and a strong mixing of exciton states is\nreported. The main focus is on the $1S$ ortho exciton-polariton, for which\npronounced polariton effects have been measured in experiments. We set up a\n$5\\times 5$ matrix model, which accounts for both the polariton effect and the\n$K$-dependent splitting, and which allows treating the anisotropic polariton\ndispersion for any direction of $\\boldsymbol{K}$. We especially discuss the\ndispersions for $\\boldsymbol{K}$ being oriented in the planes perpendicular to\n$[1\\bar{1}0]$ and $[111]$, for which experimental transmission spectra have\nbeen measured. Furthermore, we compare our results with experimental values of\nthe $K$-dependent splitting, the group velocity, and the oscillator strengths\nof this exciton-polariton."
    },
    {
        "anchor": "Phase stability and defect studies of Mg-based Laves phases using defect\n  phase diagrams: Laves phases often form as secondary phases in metallic alloys and have a\nsignificant effect on their structural properties. Thus, phase stability\nstudies for these chemically and structurally complex phases in addition to\nmechanical behavior studies are of great interest. In this work, we use the\nconcept of metastable bulk phase and defect phase diagrams to augment the\nunderstanding of the bulk phase and defect phase stability in Laves phases in\nMg-based alloys. In this way, we resolve the discrepancy between bulk phase\ndiagrams and experimental observations regarding the formation of Mg-rich C14\nand Al-rich C15 Laves phases in MgAlCa alloys at moderate temperatures.\nMoreover, the effect of the thermodynamic state of alloys on the competition\nbetween solute-rich hcp-like planar defects and stoichiometric basal stacking\nfaults is clarified, which determines the brittleness of these alloys.\n\\end{abstract}",
        "positive": "Time- and momentum-resolved phonon population dynamics with ultrafast\n  electron diffuse scattering: Interactions between the lattice and charge carriers can drive the formation\nof phases and ordering phenomena that give rise to conventional\nsuperconductivity, insulator-to-metal transitions, and charge-density waves.\nThese couplings also play a determining role in properties that include\nelectric and thermal conductivity. Ultrafast electron diffuse scattering (UEDS)\nhas recently become a viable laboratory-scale tool to track energy flow into\nand within the lattice system across the entire Brillouin zone, and deconvolves\ninteractions in the time domain. Here, we present a detailed quantitative\nframework for the interpretation of UEDS signals, ultimately extracting the\nphonon mode occupancies across the entire Brillouin zone. These transient\npopulations are then used to extract momentum- and mode-dependent\nelectron-phonon and phonon-phonon coupling constants. Results of this analysis\nare presented for graphite, which provides complete information on the\nphonon-branch occupations and a determination of the $A_1'$ phonon\nmode-projected electron-phonon coupling strength $\\langle g_{e,A_1'}^2 \\rangle\n= 0.035 \\pm 0.001$ eV$^2$ that is in agreement with other measurement\ntechniques and simulations."
    },
    {
        "anchor": "Hyperfine magnetic field in ferromagnetic graphite: Information on atomic-scale features is required for a better understanding\nof the mechanisms leading to magnetism in non-metallic, carbon-based materials.\nThis work reports a direct evaluation of the hyperfine magnetic field produced\nat 13C nuclei in ferromagnetic graphite by nuclear magnetic resonance (NMR).\nThe experimental investigation was made possible by the results of\nfirst-principles calculations carried out in model systems, including graphene\nsheets with atomic vacancies and graphite nanoribbons with edge sites partially\npassivated by oxygen. A similar range of maximum hyperfine magnetic field\nvalues (18-21T) was found for all systems, setting the frequency span to be\ninvestigated in the NMR experiments; accordingly, a significant 13C NMR signal\nwas detected close to this range without any external applied magnetic field in\nferromagnetic graphite.",
        "positive": "Significant four-phonon scattering and its heat transfer implications in\n  crystalline Ge$_2$Sb$_2$Te$_5$: We systematically demonstrate the temperature-dependent thermal transport\nproperties in crystalline Ge$_2$Sb$_2$Te$_5$via first-principles density\nfunctional theory-informed linearized Boltzmann transport equation. The\ninvestigation, covering a wide temperature range (30 K-600 K), reports the\nemergence of an unusual optical phonon-dominated thermal transport in\ncrystalline Ge$_2$Sb$_2$Te$_5$. Further, a significant contribution of\nfour-phonon scattering is recorded which markedly alters the lattice thermal\nconductivity. Therefore, the combined effect of cubic and quartic phonon\nanharmonicity is seen to navigate the underlying physical mechanism and open up\nintriguing phononic interactions in Ge$_2$Sb$_2$Te$_5$ at high temperature.\nIrrespective of three and four-phonon processes, Umklapp is seen to prevail\nover normal scattering events. Consequently, four-phonon scattering is found to\nnotably reduce the lattice thermal conductivity of Ge$_2$Sb$_2$Te$_5$ to 28\n$\\%$ at room temperature and 42 $\\%$ at higher temperature. This quartic\nanharmonicity further manifests in the breakdown of T$^{-1}$ scaling of thermal\nconductivity and challenges the idea of a universal lower bound to phononic\nthermal diffusivity at high temperature. The faster decay of thermal\ndiffusivity compared to T$^{-1}$ is rationalized encompassing the quartic\nanharmonicity via a modified time scale. These results invoke better\nunderstanding and precision to the theoretical prediction of thermal transport\nproperties of Ge$_2$Sb$_2$Te$_5$. Concomitantly, this also triggers the\npossibility to explore the manifestations of the lower bound of thermal\ndiffusivity in materials possessing pronounced four-phonon scattering."
    },
    {
        "anchor": "Structural, Morphological, Optical and Magnetic Property of Mn doped\n  Ferromagnetic ZnO thin film: The structural, optical and magnetic properties of the Zn1-xMnxO (0 < x <\n0.05) thin films synthesized by sol-gel technique have been analyzed in the\nlight of modification of the electronic structure and disorder developed in the\nsamples due to Mn doping. The films are of single phase in nature and no\nformation of any secondary phase has been detected from structural analysis.\nAbsence of magnetic impurity phase in these films confirmed from morphological\nstudy also. Increasing tendency of lattice parameters and unit cell volume has\nbeen observed with increasing Mn doping concentration. The incorporation of\nMn2+ ions introduces disorder in the system. That also leads to slight\ndegradation in crystalline quality of the films with increasing doping. The\ngrain size reduces with increase in Mn doping proportion. The band gaps shows\nred shift with doping and the width of localized states shows an increasing\ntendency with doping concentration. It is due to the formation of impurity band\nand trapping of Mn atoms, which leads to the generation of the defect states\nwithin the forbidden band. Photoluminescence (PL) spectra shows gradual\ndecrease of intensity of exitonic and defect related peaks with increasing Mn\ndoping. Defect mediated intrinsic ferromagnetism has been observed even at room\ntemperaturenfor 5at% Mn doped ZnO film. The strong presence of\nantiferromagnetic (AFM) interaction reduces the observed ferromagnetic moments.",
        "positive": "Observation of localized ferromagnetic resonance in a continuous\n  ferromagnetic film via magnetic resonance force microscopy: We present Magnetic Resonance Force Microscopy (MRFM) measurements of\nFerromagnetic Resonance (FMR) in a 50 nm thick permalloy film, tilted with\nrespect to the direction of the external magnetic field. At small probe-sample\ndistances the MRFM spectrum breaks up into multiple modes, which we identify as\nlocal ferromagnetic resonances confined by the magnetic field of the MRFM tip.\nMicromagnetic simulations support this identification of the modes and show\nthey are stabilized in the region where the dipolar tip field has a component\nanti-parallel to the applied field."
    },
    {
        "anchor": "Effects of Pressure on Electron Transport and Local Structure of\n  Manganites: Low to High Pressure Regime: The pressure dependence of the resistivity and structure of\nLa0.60Y0.07Ca0.33MnO3 has been explored in the pressure range from 1 atm to ~7\nGPa. The metal to insulator transition temperature (TMI) was found to reach a\nmaximum and the resistivity achieves a minimum at ~3.8 GPa. Beyond this\npressure, TMI is reduced with a concomitant increase in the resistivity.\nStructural measurements at room temperature show that at low pressure (below 2\nGPa) the Mn-O bond lengths are compressed. Between ~2 and ~4 GPa, a pressure\ninduced enhancement of the Jahn-Teller (JT) distortion occurs in parallel with\nan increase in Mn-O1-Mn bond angle to ~180 (degree). Above ~4 GPa, the Mn-O1-Mn\nbond angle is reduced while the JT distortion appears to remain unchanged. The\nresistivity above TMI is well modeled by variable range hopping. The pressure\ndependence of the localization length follows the behavior of TMI.",
        "positive": "Theoretical evidence for unexpected O-rich phases at corners of MgO\n  surfaces: Realistic oxide materials are often semiconductors, in particular at elevated\ntemperatures, and their surfaces contain undercoordiated atoms at structural\ndefects such as steps and corners. Using hybrid density-functional theory and\nab initio atomistic thermodynamics, we investigate the interplay of\nbond-making, bond-breaking, and charge-carrier trapping at the corner defects\nat the (100) surface of a p-doped MgO in thermodynamic equilibrium with an O2\natmosphere. We show that by manipulating the coordination of surface atoms one\ncan drastically change and even reverse the order of stability of reduced\nversus oxidized surface sites."
    },
    {
        "anchor": "Interplay of Magnetism and Transport in HoBi: We report the observation of an extreme magnetoresistance (XMR) in HoBi with\na large magnetic moment from Ho f-electrons. Neutron scattering is used to\ndetermine the magnetic wave vectors across several metamagnetic (MM)\ntransitions on the phase diagram of HoBi. Unlike other magnetic rare-earth\nmonopnictides, the field dependence of resistivity in HoBi is non-monotonic and\nreveals clear signatures of every metamagnetic transition in the\nlow-temperature and low-field regime, at T < 2 K and H < 2.3 T. The XMR appears\nat H > 2.3 T after all the metamagnetic transitions are complete and the system\nis spin-polarized by the external magnetic field. The existence of an onset\nfield for XMR and the intimate connection between magnetism and transport in\nHoBi are unprecedented among the magnetic rare-earth monopnictides. Therefore,\nHoBi provides a unique opportunity to understand the electrical transport in\nmagnetic XMR semimetals.",
        "positive": "Growth and Strain Engineering of Trigonal Te for Topological Quantum\n  Phases in Non-Symmorphic Chiral Crystals: Strained trigonal Te has been predicted to host Weyl nodes supported by a\nnon-symmorphic chiral symmetry. Using low-pressure physical vapor deposition,\nwe systematically explored the growth of trigonal Te nanowires with naturally\noccurring strain caused by curvature of the wires. Raman spectra and high\nmobility electronic transport attest to the highly crystalline nature of the\nwires. Comparison of Raman spectra for both straight and curved nanowires\nindicates a breathing mode that is significantly broader and shifted in\nfrequency for the curved wires. Strain induced by curvature during growth\ntherefore may provide a simple pathway to investigate topological phases in\ntrigonal Te."
    },
    {
        "anchor": "A Discrete-to-Continuum Model of Weakly Interacting Incommensurate\n  Two-Dimensional Lattices: The hexagonal case: In this paper, we extend the discrete-to-continuum procedure we developed in\nour previous work to derive a continuum variational model for a hexagonal\ntwisted bilayer material in which one layer is fixed. We use a discrete energy\ncontaining elastic terms and a weak interaction term that could utilize either\na Lennard-Jones potential or a Kolmogorov-Crespi potential. To validate our\nmodeling, we perform numerical simulations to compare the predictions of the\noriginal discrete model and the proposed continuum model, which also show an\nagreement with experimental findings for, e.g., twisted bilayer graphene.",
        "positive": "Strain-induced half-metallic ferromagnetism in zinc blende CrP/MnP\n  superlattice: First-principles study: Using first-principles calculations within generalized gradient\napproximation, the electronic and magnetic properties of zinc blende (zb)\nCrP/MnP superlattice are investigated. The equilibrium lattice constant is\ncalculated to be $5.33\\,$\\AA. The stability of ferromagnetic zb CrP/MnP\nsuperlattice against antiferromagnetism is considered and it is found that the\nferromagnetic CrP/MnP superlattice is more stable than the antiferromagnetic\none. It is shown that at the equilibrium lattice constant the CrP/MnP\nsuperlattice does not show any half metallicity mainly due to the minority\n$t_{2g}$ states of Cr and Mn. However, if strain is imposed on the CrP/MnP\nsuperlattice then the minority $t_{2g}$ electrons shift to higher energies and\nthe proposed superlattice becomes a half-metal ferromagnet. The effect of\ntetragonal and orthorhombic distortions on the half metallicity of zb CrP/MnP\nsuperlattice is also discussed. It is also shown that InP-CrP/MnP/InP is a true\nhalf-metal ferromagnet. The half metallicity and magnetization of these\nsuperlattices are robust against tetragonal/ orthorhombic deformation."
    },
    {
        "anchor": "First-principles many-body study of the electronic and optical\n  properties of CsK2Sb, a semiconducting material for ultra-bright electron\n  sources: We present a comprehensive first-principles investigation of the electronic\nand optical properties of CsK2Sb, a semiconducting material for ultra-bright\nelectron sources for particle accelerators. Our study, based on\ndensity-fuctional theory and many-body perturbation theory, provides all the\ningredients to model the emission of this material as a photocathode, including\nband gap, band dispersion, and optical absorption. An accurate description of\nthese properties beyond the mean-field picture is relevant to take into account\nmany-body effects. We discuss our results in the context of state-of-the-art\nelectron sources for particle accelerators to set the stage towards improved\nmodeling of quantum efficiency, intrinsic emittance, and other relevant\nquantities determining the macroscopic characteristics of photocathodes for\nultra-bright beams.",
        "positive": "Function follows form: From semiconducting to metallic towards\n  superconducting PbS nanowires by faceting the crystal: In the realm of colloidal nanostructures, with its immense capacity for shape\nand dimensionality control, the form is undoubtedly a driving factor for the\ntunability of optical and electrical properties in semiconducting or metallic\nmaterials. However, influencing the fundamental properties is still challenging\nand requires sophisticated surface or dimensionality manipulation. In this\nwork, we present such a modification for the example of colloidal lead sulphide\nnanowires. We show that the electrical properties of lead sulphide\nnanostructures can be altered from semiconducting to metallic with indications\nof superconductivity, by exploiting the flexibility of the colloidal synthesis\nto sculpt the crystal and to form different surface facets. A particular\nmorphology of lead sulphide nanowires has been synthesized through the\nformation of {111} surface facets, which shows metallic and superconducting\nproperties in contrast to other forms of this semiconducting crystal, which\ncontain other surface facets ({100} and {110}). This effect, which has been\ninvestigated with several experimental and theoretical approaches, is\nattributed to the presence of lead rich {111} facets. The insights promote new\nstrategies for tuning the properties of crystals as well as new applications\nfor lead sulphide nanostructures."
    },
    {
        "anchor": "Tunneling anisotropic magnetoresistance driven by magnetic phase\n  transition: The independent control of two magnetic electrodes and spin-coherent\ntransport in magnetic tunnel junctions are strictly required for tunneling\nmagnetoresistance, while junctions with only one ferromagnetic electrode\nexhibit tunneling anisotropic magnetoresistance dependent on the anisotropic\ndensity of states with no room temperature performance so far. Here we report\nan alternative approach to obtaining tunneling anisotropic magnetoresistance in\nalfa-FeRh-based junctions driven by the magnetic phase transition of alfa-FeRh\nand resultantly large variation of the density of states in the vicinity of MgO\ntunneling barrier, referred to as phase transition tunneling anisotropic\nmagnetoresistance. The junctions with only one alfa-FeRh magnetic electrode\nshow a magnetoresistance ratio up to 20% at room temperature. Both the polarity\nand magnitude of the phase transition tunneling anisotropic magnetoresistance\ncan be modulated by interfacial engineering at the alfa-FeRh/MgO interface.\nBesides the fundamental significance, our finding might add a different\ndimension to magnetic random access memory and antiferromagnet spintronics.",
        "positive": "Pressure-driven electronic and structural phase transition in intrinsic\n  magnetic topological insulator MnSb2Te4: Intrinsic magnetic topological insulators provide an ideal platform to\nachieve various exciting physical phenomena. However, this kind of materials\nand related research are still very rare. In this work, we reported the\nelectronic and structural phase transitions in intrinsic magnetic topological\ninsulator MnSb2Te4 driven by hydrostatic pressure. Electric transport results\nrevealed that temperature dependent resistance showed a minimum value near\nshort-range antiferromagnetic (AFM) ordering temperature TN', the TN' values\ndecline with pressure, and the AFM ordering was strongly suppressed near 10 GPa\nand was not visible above 11.5 GPa. The intensity of three Raman vibration\nmodes in MnSb2Te4 declined quickly starting from 7.5 GPa and these modes become\nundetectable above 9 GPa, suggesting possible insulator-metal transition, which\nis further confirmed by theoretical calculation. In situ x-ray diffraction\n(XRD) demonstrated that an extra diffraction peak appears near 9.1 GPa and\nMnSb2Te4 started to enter an amorphous-like state above 16.6 GPa, suggesting\nthe structural origin of suppressed AFM ordering and metallization. This work\nhas demonstrated the correlation among interlayer interaction, magnetic\nordering, and electric behavior, which could be benefit for the understanding\nof the fundamental properties of this kind of materials and devices."
    },
    {
        "anchor": "Dielectric relaxation and Charge trapping characteristics study in\n  Germanium based MOS devices with HfO2 /Dy2O3 gate stacks: In the present work we investigate the dielectric relaxation effects and\ncharge trapping characteristics of HfO2 /Dy2O3 gate stacks grown on Ge\nsubstrates. The MOS devices have been subjected to constant voltage stress\n(CVS) conditions at accumulation and show relaxation effects in the whole range\nof applied stress voltages. Applied voltage polarities as well as thickness\ndependence of the relaxation effects have been investigated. Charge trapping is\nnegligible at low stress fields while at higher fields (>4MV/cm) it becomes\nsignificant. In addition, we give experimental evidence that in tandem with the\ndielectric relaxation effect another mechanism- the so-called Maxwell-Wagner\ninstability- is present and affects the transient current during the\napplication of a CVS pulse. This instability is also found to be field\ndependent thus resulting in a trapped charge which is negative at low stress\nfields but changes to positive at higher fields.",
        "positive": "Valence band splitting in bulk dilute bismides: The electronic structure of bulk GaAs$_{1-x}$Bi$_x$ systems for different\natomic configurations and Bi concentrations is calculated using density\nfunctional theory. The results show a Bi-induced splitting between the\nlight-hole and heavy-hole bands at the $\\Gamma$-point. We find a good agreement\nbetween our calculated splittings and experimental data. The magnitude of the\nsplitting strongly depends on the local arrangement of the Bi atoms but not on\nthe uni-directional lattice constant of the supercell. The additional influence\nof external strain due to epitaxial growth on GaAs substrates is studied by\nfixing the in-plane lattice constants."
    },
    {
        "anchor": "Theoretical prediction of topological insulator in ternary rare earth\n  chalcogenides: A new class of three-dimensional topological insulator, ternary rare earth\nchalcogenides, is theoretically investigated with ab initio calculations. Based\non both bulk band structure analysis and the direct calculation of topological\nsurface states, we demonstrate that LaBiTe3 is a topological insulator. La can\nbe substituted by other rare earth elements, which provide candidates for novel\ntopological states such as quantum anomalous Hall insulator, axionic insulator\nand topological Kondo insulator. Moreover, YBiTe3 and YSbTe3 are found to be\nnormal insulators. They can be used as protecting barrier materials for both\nLaBiTe3 and Bi2Te3 families of topological insulators for their well matched\nlattice constants and chemical composition.",
        "positive": "Mo_6S_6 nanowires: structural, mechanical and electronic properties: The properties of Mo_6S_6 nanowires were investigated with ab-initio\ncalculations based on the density-functional theory. The molecules build weakly\ncoupled one-dimensional chains, like Mo_6Se_6 and Mo_6S_(9-x)I_x, and the\ncrystals are strongly uniaxial in their mechanical and electronic properties.\nThe calculated moduli of elasticity and resilience along the chain axis are\nc_(11) = 320 GPa and E_R = 0.53 GPa, respectively. The electronic band\nstructure and optical conductivity indicate that the Mo_6S_6 crystals are good\nquasi-one-dimensional conductors. The frequency-dependent complex dielectric\ntensor epsilon, calculated in the random-phase approximation, shows a strong\nDrude peak in epsilon_parallel, i.e., for the electric field polarised parallel\nto the chain axis, and several peaks related to interband transitions. The\nelectron energy loss spectrum is weakly anisotropic and has a strong peak at\nthe plasma frequency (hbar omega_p) is approx 20 eV. The stability analysis\nshows that Mo_6S_6 is metastable against the formation of the layered MoS_2."
    },
    {
        "anchor": "One-dimensional ordered structure of a-sexithienyl on Cu(110): We have studied atomic structures of a-sexithienyl (6T) films grown on\nCu(110) by near-edge x-ray absorption fine structure (NEXAFS). A\none-dimensional (1D) ordered structure of 6T with its molecular long axis\nparallel to the Cu[001] direction could be fabricated by deposition at 300 K\nand subsequent annealing at 360 K. Polarization and azimuth-dependent NEXAFS\nrevealed the formation process of the 1D structure and showed the molecular\norientation in the in-plane direction directly. We propose here a method to\nobtain the orientation distribution function of molecules using NEXAFS.",
        "positive": "Magnetic anisotropy switching in (Ga,Mn)As with increasing hole\n  concentration: We study a possible mechanism of the switching of the magnetic easy axis as a\nfunction of hole concentration in (Ga,Mn)As epilayers. In-plane uniaxial\nmagnetic anisotropy along [110] is found to exceed intrinsic cubic\nmagnetocrystalline anisotropy above a hole concentration of p = 1.5 * 10^21\ncm^-3 at 4 K. This anisotropy switching can also be realized by post-growth\nannealing, and the temperature-dependent ac susceptibility is significantly\nchanged with increasing annealing time. On the basis of our recent scenario\n[Phys. Rev. Lett. 94, 147203 (2005); Phys. Rev. B 73, 155204 (2006).], we\ndeduce that the growth of highly hole-concentrated cluster regions with [110]\nuniaxial anisotropy is likely the predominant cause of the enhancement in [110]\nuniaxial anisotropy at the high hole concentration regime. We can clearly rule\nout anisotropic lattice strain as a possible origin of the switching of the\nmagnetic anisotropy."
    },
    {
        "anchor": "Spin Resistivity in Frustrated Antiferromagnets: In this paper we study the spin transport in frustrated antiferromagnetic FCC\nfilms by Monte Carlo simulation. In the case of Ising spin model, we show that\nthe spin resistivity versus temperature exhibits a discontinuity at the phase\ntransition temperature: an upward jump or a downward fall, depending on how\nmany parallel and antiparallel localized spins interacting with a given\nitinerant spin. The surface effects as well as the difference of two degenerate\nstates on the resistivity are analyzed. Comparison with non frustrated\nantiferromagnets is shown to highlight the frustration effect. We also show and\ndiscuss the results of the Heisenberg spin model on the same lattice.",
        "positive": "Atomistic aspects of load transfer and fracture in CNT-reinforced\n  aluminium: This paper describes atomistic simulations of deformation and fracture of Al\nreinforced with carbon nanotubes (CNTs). We use density functional theory (DFT)\nto understand the energetics of Al-graphene interfaces and gain reference data\nfor the parameterization of Al-C empirical potentials. We then investigate the\nload transfer between CNTs and Al and its effect on composite strengthening. To\nthis end, we perform uniaxial tensile simulations of an Al crystal reinforced\nwith CNTs of various volume fractions. We also study the interaction of the\nembedded CNTs with a crack. We show that the interaction between CNTs and Al is\nweak such that, under tensile loading, CNTs can easily slide inside the Al\nmatrix and get pulled out from the cracked surface. This effect is almost\nindependent of CNT length and volume fraction. Little load transfer and\nconsequently no crack bridging are observed during the simulation of pristine\nCNTs threading the crack surfaces. CNTs that are geometrically fixated inside\nAl, on the other hand, can increase the fracture stress and enhance plastic\ndissipation in the matrix. CNTs located in front of a growing crack blunt the\ncrack and induce plastic deformation of the Al matrix. Depending on the CNT\norientation, these processes can either increase or decrease the failure stress\nof the composite."
    },
    {
        "anchor": "Band Structure Theory of the BCC to HCP Burgers Distortion: The Burgers distortion is a two-stage transition between body centered cubic\n(BCC) and hexagonal close-packed (HCP) structures. Refractory metal elements\nfrom the Sc and Ti columns of the periodic table (BCC/HCP elements) form BCC\nstructures at high temperatures but transition to HCP at low temperatures via\nthe Burgers distortion. Elements of the V and Cr columns, in contrast, remain\nBCC at all temperatures. The energy landscape of BCC/HCP elements exhibits an\nalternating slide instability, while the normal BCC elements remain stable as\nBCC structures. This instability is verified by the presence of unstable\nelastic constants and vibrational modes for BCC/HCP elements, while those\nelastic constants and modes are stable in BCC elements. We show that a\npseudogap opening in the density of states at the Fermi level drives the\nBurgers distortion in BCC/HCP elements, suggesting the transition is of the\nJahn-Teller-Peierls type. The pseudogap lies below the Fermi level for regular\nBCC elements in the V and Cr columns of the periodic table. The wave vector\n$k_S$ when the gap opens relates to the reciprocal lattice vector G=(1\n$\\frac{1}{2}$ $\\frac{1}{2}$) of the distorted BCC structure as\n$k_S$=$\\frac{1}{2}$G. BCC binary alloys containing both BCC/HCP and BCC\nelements exhibit a similar instability but stabilize part way through the BCC\nto HCP transition.",
        "positive": "Diffusion of elastic waves in a two dimensional continuum with a random\n  distribution of screw dislocations: We study the diffusion of anti-plane elastic waves in a two dimensional\ncontinuum by many, randomly placed, screw dislocations. Building on a\npreviously developed theory for coherent propagation of such waves, the\nincoherent behavior is characterized by way of a Bethe Salpeter (BS) equation.\nA Ward-Takahashi identity (WTI) is demonstrated and the BS equation is solved,\nas an eigenvalue problem, for long wavelengths and low frequencies. A diffusion\nequation results and the diffusion coefficient $D$ is calculated. The result\nhas the expected form $D = v^* l /2$, where $l$, the mean free path, is equal\nto the attenuation length of the coherent waves propagating in the medium and\nthe transport velocity is given by $v^*= c_T^2/v$, where $c_T$ is the wave\nspeed in the absence of obstacles and $v$ is the speed of coherent wave\npropagation in the presence of dislocations."
    },
    {
        "anchor": "Precipitate assemblies formed on dislocation loops in aluminium-silver\n  alloys: A detailed study of the precipitation of the \\gamma' (AlAg2) phase in\nundeformed aluminium-silver alloys has been conducted. Several previously\nunreported features were observed, including the formation of discrete\nthree-dimensional assemblies comprised of 5-7 precipitates on faulted\ndislocation loops. The precipitates assemblies adopted a morphology\napproximating a tetrahedral bipyramidal assembly. The bounding defect of the\nstacking fault was found to control both the nucleation of additional\nprecipitates which was responsible for the formation of the assembly structure\nand also the growth characteristics of individual precipitates with these\nassemblies.",
        "positive": "Fate of a soliton matter upon symmetry-breaking ferroelectric order: In a one-dimensional (1D) system with degenerate ground states, their domain\nboundaries, dubbed solitons, emerge as topological excitations often carrying\nunconventional charges and spins; however, the soliton excitations are only\nvital in the non-ordered 1D regime. Then a question arises; how do the solitons\nconform to a 3D ordered state? Here, using a quasi-1D organic ferroelectric,\nTTF-CA, with degenerate polar dimers, we pursue the fate of a spin-soliton\ncharge-soliton composite matter in a 1D polar-dimer liquid upon its transition\nto a 3D ferroelectric order by resistivity, NMR and NQR measurements. We\ndemonstrate that the soliton matter undergoes neutral spin-spin soliton pairing\nand spin-charge soliton pairing to form polarons, coping with the 3D order. The\nformer contributes to the magnetism through triplet excitations whereas the\nlatter carries electrical current. Our results reveal the whole picture of a\nsoliton matter that condenses into the 3D ordered state."
    },
    {
        "anchor": "Generalized Kohn-Sham Approach for the Electronic Band Structure of\n  Spin-Orbit Coupled Materials: Spin-current density functional theory (SCDFT) is a formally exact framework\ndesigned to handle the treatment of interacting many-electron systems including\nspin-orbit coupling at the level of the Pauli equation. In practice, robust and\naccurate calculations of the electronic structure of these systems call for\nfunctional approximations that depend not only on the densities, but also on\nspin-orbitals. Here we show that the call can be answered by resorting to an\nextension of the Kohn-Sham formalism, which admits the use of non-local\neffective potentials, yet it is firmly rooted in SCDFT. The power of the\nextended formalism is demonstrated by calculating the spin-orbit-induced\nband-splittings of inversion-asymmetric MoSe$_2$ monolayer and\ninversion-symmetric bulk $\\alpha$-MoTe$_2$. We show that quantitative agreement\nwith experimental data is obtainable via global hybrid approximations by\nsetting the fraction of Fock exchange at the same level which yields accurate\nvalues of the band gap. Key to these results is the ability of the method to\nself-consistently account for the spin currents induced by the spin-orbit\ninteraction. The widely used method of refining spin-density functional theory\nby a second-variational treatment of spin-orbit coupling is unable to match our\nSCDFT results.",
        "positive": "Optical Properties of Ultrashort Semiconducting Single-Walled Carbon\n  Nanotube Capsules Down to Sub-10 nm: Single-walled carbon nanotubes (SWNTs) are typically long (>100 nm) and have\nbeen well established as novel quasi one-dimensional systems with interesting\nelectrical, mechanical, and optical properties. Here, quasi zero-dimensional\nSWNTs with finite lengths down to the molecular scale (7.5 nm in average) were\nobtained by length separation using a density gradient ultracentrifugation\nmethod. Different sedimentation rates of nanotubes with different lengths in a\ndensity gradient were taken advantage of to sort SWNTs according to length.\nOptical experiments on the SWNT fractions revealed that the UV-vis-NIR\nabsorption and photoluminescence peaks of the ultrashort SWNTs blue-shift up to\n30 meV compared to long nanotubes, owing to quantum confinement effects along\nthe length of ultrashort SWNTs. These nanotube capsules essentially correspond\nto SWNT quantum dots."
    },
    {
        "anchor": "Strain glass versus antisite disorder induced ferromagnetic state in Fe\n  doped Ni-Mn-In Heusler martensites: Fe doping in Ni$_2$Mn$_{1.5}$In$_{0.5}$ results in suppression of the\nmartensitic phase via two contrasting routes. In\nNi$_2$Mn$_{1.5-x}$Fe$_{x}$In$_{0.5}$, the martensitic phase is converted to a\nstrain glassy phase, while in Ni$_{2-y}$Fe$_y$Mn$_{1.5}$In$_{0.5}$, a cubic\nferromagnetic phase results at the expense of the martensite. Careful studies\nof magnetic and structural properties reveal the presence of the impurity\n$\\gamma -$(Fe,Ni) phase as the reason for the emergence of non-ergodic strain\nglassy phase when Fe is sought to be doped at Y/Z (Mn) sites of X$_2$YZ Heusler\nalloy. Whereas attempts to dope Fe in the X (Ni) sublattice result in an A2\ntype antisite disorder that promotes a ferromagnetic ground state.",
        "positive": "Mechanism of Polarization Fatigue in BiFeO3: the Role of Schottky\n  Barrier: By using piezoelectric force microscopy and scanning Kelvin probe microscopy,\nwe have investigated the domain evolution and space charge distribution in\nplanar BiFeO3 capacitors with different electrodes. It is observed that charge\ninjection at the film/electrode interface leads to domain pinning and\npolarization fatigue in BiFeO3. Furthermore, the Schottky barrier at the\ninterface is crucial for the charge injection process. Lowering the Schottky\nbarrier by using low work function metals as the electrodes can also improve\nthe fatigue property of the device, similar to what oxide electrodes can\nachieve."
    },
    {
        "anchor": "An infrared, Raman, and X-ray database of battery interphase components: Further technological advancement of both lithium-ion and emerging battery\ntechnologies can be catalyzed by an improved understanding of the chemistry and\nworking mechanisms of the solid electrolyte interphases (SEIs) that form at\nelectrochemically active battery interfaces. However, collecting and\ninterpreting spectroscopy results of SEIs is difficult for several reasons,\nincluding the chemically diverse composition of SEIs. To address this\nchallenge, we herein present a vibrational spectroscopy and X-ray diffraction\ndata library of ten suggested SEI chemical constituents relevant to both\nlithium-ion and emerging battery chemistries. The data library includes\nattenuated total reflectance Fourier transform infrared spectroscopy, Raman\nspectroscopy, and X-ray diffraction data, collected in inert atmospheres\nafforded by custom designed sample holders. The data library presented in this\nwork (and online repository) alleviates challenges with locating related work\nthat is either diffusely spread throughout the literature, or is non-existent,\nand provides energy storage researchers streamlined access to vital\nSEI-relevant data that can catalyse future battery research efforts.",
        "positive": "360 degree domain wall generation in the soft layer of magnetic tunnel\n  junctions: High spatial resolution X-ray photo-emission electron microscopy technique\nhas been used to study the influence of the dipolar coupling taking place\nbetween the NiFe and the Co ferromagnetic electrodes of micron sized,\nelliptical shaped magnetic tunnel junctions. The chemical selectivity of this\ntechnique allows to observe independently the magnetic domain structure in each\nferromagnetic electrode. The combination of this powerful imaging technique\nwith micromagnetic simulations allows to evidence that a 360 degree domain wall\ncan be stabilized in the NiFe soft layer. In this letter, we discuss the origin\nand the formation conditions of those 360 degree domain walls evidenced\nexperimentally and numerically."
    },
    {
        "anchor": "Dislocation healing during hydrogen absorption and desorption in\n  palladium: An in-situ neutron diffraction investigation of the annealing and healing of\ndislocations in the bulk Pd-D2 system was carried out. Lattice misfit between\nthe alpha and beta hydride phases produces dislocations during the phase\ntransition in either direction, relieving elastic strain, which is reflected in\nreduced pressure hysteresis compared to the spinodal hysteresis. The effects on\nthe dislocation density of annealing the metal under vacuum, of annealing in\nthe beta hydride phase, and of the phase transformation itself were\ninvestigated by measuring diffraction peak breadths during annealing and\nhydrogen cycling. During annealing under vacuum the dislocations were removed\nat a lower temperature than was previously reported, but annealing in the beta\nphase gave nearly the same result. However, when cycling hydrogen in and out of\nthe sample, the dislocation density decreased much faster with increasing\ntemperature compared to annealing. In other words the process of phase\ntransformation allows for healing of dislocations at lower temperatures than\nwould be required to anneal them purely by heating. This healing effect was\nobserved during both absorption and desorption. This result illuminates the\nmechanism by which misfit dislocations can be healed at the same rate that they\nare created in a sample undergoing absorption-desorption cycling, as proposed\nin theoretical models of the origin of pressure hysteresis.",
        "positive": "Ab initio study of the density dependence of the Gr\u00fcneisen parameter\n  at pressures up to 360 GPa: Ab initio calculations based on the Density Functional Theory are used to\nshow that the Debye frequency is a linear function of density to a high\naccuracy for several elemental solids at pressures (at least) up to 360 GPa.\nThis implies that the ratio of density over the (Debye-frequency-based)\nvibrational Gr\\\"{u}neisen parameter is a linear function of density in this\nregion. Numerical data from first principles calculations for several systems\nat temperatures up to 2000K suggest that this is also true for the thermal\nGr\\\"{u}neisen parameter in the same range of pressure. Our analytical form of\nthe vibrational Gr\\\"{u}neisen parameter is applied to an implementation of the\nLindemann's melting criterion to obtain a simple extrapolation formula for the\nmelting temperatures of materials at higher densities. This prediction is\ntested against available experimental and numerical data for several elemental\nsolids."
    },
    {
        "anchor": "Multi-step stochastic mechanism of polarization reversal in rhombohedral\n  ferroelectrics: A stochastic model for the field-driven polarization reversal in rhombohedral\nferroelectrics is developed, providing a description of their temporal\nelectromechanical response. Application of the model to simultaneous\nmeasurements of polarization and strain kinetics in a rhombohedral Pb(Zr,Ti)O3\nceramic over a wide time window allows identification of preferable switching\npaths, fractions of individual switching processes, and their activation\nfields. Complementary, the phenomenological Landau-Ginzburg-Devenshire theory\nis used to analyze the impact of external field and stress on switching\nbarriers showing that residual mechanical stress may promote the fast\nswitching.",
        "positive": "Nuclear resonant surface diffraction: Nuclear resonant x-ray diffraction in grazing incidence geometry is used to\ndetermine the lateral magnetic configuration in a one-dimensional lattice of\nferromagnetic nanostripes. During magnetic reversal, strong nuclear\nsuperstructure diffraction peaks appear in addition to the electronic ones due\nto an antiferromagnetic order in the nanostripe lattice. We show that the\nanalysis of the angular distribution of the resonantly diffracted x-rays\ntogether with the time-dependence of the coherently diffracted nuclear signal\nreveals surface spin structures with very high sensitivity. This novel\nscattering technique provides a unique access to laterally correlated spin\nconfigurations in magnetically ordered nanostructures and, in perspective, also\nto their dynamics."
    },
    {
        "anchor": "Electrical transport through self-assembled colloidal nanomaterials and\n  their perspectives: Colloidal nanoparticles developed as interesting objects to establish two- or\nthree-dimensional super-structures with properties not known from conventional\nbulk materials. Beyond, the properties can be tuned and quantum effects can be\nexploited. This allows understanding electronic and optoelectronic transport\nphenomena and developing corresponding devices. The state-of-the-art in this\nfield will be reviewed and possible challenges and prospects will be\nidentified.",
        "positive": "Solvothermal Reduction of Chemically Exfoliated Graphene Sheets: Graphene has attracted much attention due to its interesting properties and\npotential applications. Chemical exfoliation methods have been developed to\nmake graphene recently, aimed at large-scale assembly and applications such as\ncomposites and Li ion batteries. Although efficient, the chemical exfoliation\nmethods involve oxidation of graphene and introduce defects in the as-made\nsheets. Hydrazine reduction at 100 has shown to partially restore the structure\nand conductance of graphite oxide. However, the reduced GO still shows strong\ndefect peaks in Raman spectra with higher resistivity than pristine graphene by\n2 to 3 orders of magnitude. It is important to produce much less defective\ngraphene sheets than GO, and develop more effective graphene reduction.\nRecently, we reported a mild exfoliation-reintercalation-expansion method to\nform high-quality GS with higher conductivity and lower oxidation degree than\nGO.5 Here, we present a 180 solvothermal reduction method for our GS and GO.\nThe solvothermal reduction is more effective than the earlier reduction methods\nin lowering the oxygen and defect levels in GS, increasing the graphene\ndomains, and bringing the conductivity of GS close to pristine graphene. The\nreduced GS possess the highest degree of pristinity among chemically derived\ngraphene."
    },
    {
        "anchor": "Isotropic non-local Gilbert damping driven by spin currents in epitaxial\n  Pd/Fe/MgO(001) films: Although both theoretical predications and experimental observations\ndemonstrated that the damping factor is anisotropic at\nferromagnet/semiconductor interface with robust interfacial spin-orbit\ncoupling, it is not well understood whether non-local Gilbert damping driven by\nspin currents in heavy metal/ferromagnetic metal (HM/FM) bilayers is\nanisotropic or not. Here, we investigated the in-plane angular- and frequency-\ndependence of magnetic relaxation of epitaxial Fe/MgO(001) films with different\ncapping layers of Pd and Cu. After disentangling the parasitic contributions,\nsuch as two-magnon scattering (TMS), mosaicity, and field-dragging effect, we\nunambiguously observed that both local and non-local Gilbert damping are\nisotropic in Fe(001) plane, suggesting that the pure spin currents absorption\nis independent of Fe magnetization orientation in the epitaxial Pd/Fe\nheterostructure. First principles calculation reveals that the effective spin\nmixing conductance of Pd/Fe interface is nearly invariant for different\nmagnetization directions in good agreement with the experimental observations.\nThese results offer a valuable insight into the transmission and absorption of\npure spin currents, and facilitate us to utilize next-generation spintronic\ndevices.",
        "positive": "Degenerate Density Perturbation Theory: Fractional occupation numbers can be used in density functional theory to\ncreate a symmetric Kohn-Sham potential, resulting in orbitals with degenerate\neigenvalues. We develop the corresponding perturbation theory and apply it to a\nsystem of $N_d$ degenerate electrons in a harmonic oscillator potential. The\norder-by-order expansions of both the fractional occupation numbers and unitary\ntransformations within the degenerate subspace are determined by the\nrequirement that a differentiable map exists connecting the initial and\nperturbed states. Using the X$\\alpha$ exchange-correlation (XC) functional, we\nfind an analytic solution for the first-order density and first through\nthird-order energies as a function of $\\alpha$, with and without a\nself-interaction correction. The fact that the XC Hessian is not positive\ndefinite plays an important role in the behavior of the occupation numbers."
    },
    {
        "anchor": "Fluorine doping: A feasible solution to enhancing the conductivity of\n  high-resistance wide bandgap Mg0.51Zn0.49O active components: N-type doping of high-resistance wide bandgap semiconductors, wurtzite\nhigh-Mg-content MgxZn1-xO for instance, has always been a fundamental\napplication-motivated research issue. Herein, we report a solution to enhancing\nthe conductivity of high-resistance Mg0.51Zn0.49O active components, which has\nbeen reliably achieved by fluorine doping via radio-frequency plasma assisted\nmolecular beam epitaxial growth. Fluorine dopants were demonstrated to be\neffective donors in Mg0.51Zn0.49O single crystal film having a solar-blind 4.43\neV bandgap, with an average concentration of 1.0E19 F/cm3.The dramatically\nincreased carrier concentration (2.85E17 cm-3 vs ~1014 cm-3) and decreased\nresistivity (129 ohm.cm vs ~10E6 ohm cm) indicate that the electrical\nproperties of semi-insulating Mg0.51Zn0.49O film can be delicately regulated by\nF doping. Interestingly, two donor levels (17 meV and 74 meV) associated with F\nwere revealed by temperature-dependent Hall measurements. A Schottky type\nmetal-semiconductor-metal ultraviolet photodetector manifests a remarkably\nenhanced photocurrent, two orders of magnitude higher than that of the undoped\ncounterpart. The responsivity is greatly enhanced from 0.34 mA/W to 52 mA/W\nunder 10 V bias. The detectivity increases from 1.89E9 cm Hz1/2/W to 3.58eE10\ncm Hz1/2/W under 10 V bias at room temperature.These results exhibit F doping\nserves as a promising pathway for improving the performance of high-Mg-content\nMgxZn1-xO-based devices.",
        "positive": "Impacts of propagating, frustrated and surface modes on radiative,\n  electrical and thermal losses in nanoscale-gap thermophotovoltaic power\n  generators: The impacts of radiative, electrical and thermal losses on the power output\nenhancement of nanoscale-gap thermophotovoltaic (nano-TPV) power generators\nconsisting of a gallium antimonide cell paired with a broadband tungsten and a\nradiatively-optimized Drude radiator are analyzed. Results reveal that surface\nmode mediated nano-TPV power generation with the Drude radiator outperforms the\ntungsten emitter, dominated by frustrated modes, only for a vacuum gap\nthickness of 10 nm and if both electrical and thermal losses are neglected. The\nkey limiting factors for the Drude and tungsten-based devices are respectively\nthe recombination of electron-hole pairs at the cell surface and thermalization\nof radiation with energy larger than the absorption bandgap. In a nano-TPV\npower generator cooled by convection with a fluid at 293 K and a heat transfer\ncoefficient of 10^4 Wm^-2K^-1, power output enhancements of 4.69 and 1.89 are\nobtained for the tungsten and Drude radiators, respectively, when a realistic\nvacuum gap thickness of 100 nm is considered. A design guideline is also\nproposed where a high energy cutoff above which radiation has a net negative\neffect on nano-TPV power output is determined. This work demonstrates that\ndesign and optimization of nano-TPV devices must account for radiative,\nelectrical and thermal losses."
    },
    {
        "anchor": "Synergy of Binary Substitutions for Improving the Cycle Performance in\n  LiNiO2 Revealed by Ab Initio Materials Informatics: We explore LiNiO2-based cathode materials with two-element substitutions by\nan ab initio simulation based materials informatics (AIMI) approach. According\nto our previous study, a higher cycle performance strongly correlates with less\nstructural change during charge-discharge cycles; the latter can be used for\nevaluating the former. However, if we target the full substitution space, full\nsimulations are infeasible even for all binary combinations. To circumvent such\nan exhaustive search, we rely on Bayesian optimization. Actually, by searching\nonly 4% of all the combinations, our AIMI approach discovered two promising\ncombinations, Cr-Mg and Cr-Re, whereas each atom itself never improved the\nperformance. We conclude that the synergy never emerges from a common strategy\nrestricted to combinations of \"good\" elements that individually improve the\nperformance. In addition, we propose a guideline for the binary substitutions\nby elucidating the mechanism of crystal structure change.",
        "positive": "Phonon-limited resistivity of graphene by first-principle calculations:\n  electron-phonon interactions, strain-induced gauge field and Boltzmann\n  equation: Electron-phonon coupling in graphene is extensively modeled and simulated\nfrom first principles. We find that using an accurate model for the\npolarizations of the acoustic phonon modes is crucial to obtain correct\nnumerical results. The interactions between electrons and acoustic phonon\nmodes, the gauge field and deformation potential, are calculated at the DFT\nlevel in the framework of linear response. The zero-momentum limit of acoustic\nphonons is interpreted as a strain pattern, allowing the calculation of the\nacoustic gauge field parameter in the GW approximation. The role of electronic\nscreening on the electron-phonon matrix elements is investigated. We then solve\nthe Boltzmann equation semi-analytically in graphene, including both acoustic\nand optical phonon scattering. We show that, in the Bloch-Gr\\\"uneisen and\nequipartition regimes, the electronic transport is mainly ruled by the\nunscreened acoustic gauge field, while the contribution due to the deformation\npotential is negligible and strongly screened. By comparing with experimental\ndata, we show that the contribution of acoustic phonons to resistivity is\ndoping- and substrate-independent. The DFT+GW approach underestimates this\ncontribution to resistivity by about 30 %. Above 270K, the calculated\nresistivity underestimates the experimental one more severely, the\nunderestimation being larger at lower doping. We show that, beside remote\nphonon scattering, a possible explanation for this disagreement is the\nelectron-electron interaction that strongly renormalizes the coupling to\nintrinsic optical-phonon modes. Finally, after discussing the validity of the\nMatthiessen rule in graphene, we derive simplified analytical solutions of the\nBoltzmann equation to extract the coupling to acoustic phonons, related to the\nstrain-induced gauge field, directly from experimental data."
    },
    {
        "anchor": "Sublattice mixing in Cs$_2$AgInCl$_6$ for enhanced optical properties\n  from first-principles: Lead-free double perovskite materials (viz. Cs$_2$AgInCl$_6$) are being\nexplored as stable and non-toxic alternatives of lead halide perovskites. In\norder to expand the optical response of Cs$_2$AgInCl$_6$ in visible region, we\nreport here the stability, electronic structure and optical properties of\nCs$_2$AgInCl$_6$ by sublattice mixing of various elements. Here, we have\nemployed %high-throughput screening using a hierarchical first-principles based\napproach starting from density functional theory (DFT) with appropriate\nexchange-correlation functionals to beyond DFT methods under the framework of\nmany body perturbation theory (viz. G$_0$W$_0$@HSE06). We have started with 32\nprimary set of combinations of metals M(I), M(II), M(III) and halogen X at\nAg/In and Cl site, respectively, where concentration of each set is varied to\nbuild a database of nearly 140 combinations. The most suitable mixed\nsublattices are identified to engineer the band gap of Cs$_2$AgInCl$_6$ to have\nits application in optoelectronic devices under visible light.",
        "positive": "Development of structural descriptors to predict dissolution rate of\n  volcanic glasses: molecular dynamic simulations: Establishing the composition-structure-property relationships for amorphous\nmaterials is critical for many important natural and engineering processes,\nincluding the dissolution of highly complex volcanic glasses. In this\ninvestigation, we performed force field molecular dynamics (MD) simulations to\ngenerate detailed structural representations for ten natural\nCaO-MgO-Al2O3-SiO2-TiO2-FeO-Fe2O3-Na2O-K2O glasses with compositions ranging\nfrom rhyolitic to basaltic. Based on the resulting atomic structural\nrepresentations at 300 K, we have calculated the partial radial distribution\nfunctions, nearest interatomic distances and coordination number, which are\nconsistent with the literature data on silicate-based glasses. Based on these\nstructural attributes and classical bond valence models, we have introduced a\nnovel structural descriptor, i.e., average metal-oxygen (M-O) bond strength\nparameter, which has captured the log dissolution rates of the ten glasses at\nboth acidic and basic conditions (based on literature data) with R2 values of\n~0.80-0.92 based on linear regression. This structural descriptor is seen to\noutperform several other structural descriptors also derived from MD simulation\nresults, including the average metal oxide dissociation energy, the average\nself-diffusion coefficient of all the atoms at their melting points, and the\nenergy barrier of self-diffusion. Furthermore, we showed that the MD-derived\ndescriptors generally exhibit better predictive performance than the degree of\ndepolymerization parameter commonly used to describe glass and mineral\nreactivity. The results suggest that the structural descriptors derived from MD\nsimulations, especially the average M-O bond strength parameter, are promising\nstructural descriptors for connecting composition with dissolution rates of\nhighly complex natural glasses."
    },
    {
        "anchor": "Local structure in Ag$_3$[Co(CN)$_6$]: Colossal thermal expansion, rigid\n  unit modes and argentophilic interactions: Local structure in the colossal thermal expansion material Ag$_3$[Co(CN)$_6$]\nis studied here using a combination of neutron total scattering and reverse\nMonte Carlo (RMC) analysis. We show that the large thermal variations in cell\ndimensions occur with minimal distortion of the [Co(CN)$_6$] coordination\npolyhedra, but involve significant flexing of the Co--CN--Ag--NC--Co linkages.\nWe find real-space evidence in our RMC configurations for the importance of\nlow-energy rigid unit modes (RUMs), particularly at temperatures below 150 K.\nUsing a reciprocal-space analysis we present the phonon density of states at\n300 K and show that the lowest-frequency region is dominated by RUMs and\nrelated modes. We also show that thermal variation in the energies of Ag$...$Ag\ninteractions is evident in both the Ag partial pair distribution function and\nin the Ag partial phonon density of states. These findings are discussed in\nrelation to the thermodynamic properties of the material.",
        "positive": "Ion Irradiation Control of Ferromagnetism in (Ga,Mn)As: We report on a promising approach to the artificial modification of\nferromagnetic properties in (Ga,Mn)As using a Ga$^+$ focused ion beam (FIB)\ntechnique. The ferromagnetic properties of (Ga,Mn)As such as magnetic\nanisotropy and Curie temperature can be controlled using Ga$^+$ ion\nirradiation, originating from a change in hole concentration and the\ncorresponding systematic variation in exchange interaction between Mn spins.\nThis change in hole concentration is also verified using micro-Raman\nspectroscopy. We envisage that this approach offers a means of modifying the\nferromagnetic properties of magnetic semiconductors on the micro- or nano-meter\nscale."
    },
    {
        "anchor": "AC current generation in chiral magnetic insulators and skyrmion motion\n  induced by the spin Seebeck effect: We show that a temperature gradient induces an ac electric current in\nmultiferroic insulators when the sample is embedded in a circuit. We also show\nthat a thermal gradient can be used to move magnetic skyrmions in insulating\nchiral magnets: the induced magnon flow from the hot to the cold region drives\nthe skyrmions in the opposite direction via a magnonic spin transfer torque.\nBoth results are combined to compute the effect of skyrmion motion on the ac\ncurrent generation and demonstrate that skyrmions in insulators are a promising\nroute for spin caloritronics applications.",
        "positive": "Soft phonon modes driven huge difference on lattice thermal conductivity\n  between topological semimetal WC and WN: Topological semimetals are currently attracting increasing interest due to\ntheir potential applications in topological qubits and low-power electronics,\nwhich are closely related to their thermal transport properties. In this work,\nby solving the Boltzmann transport equation based on first-principles\ncalculations, we systematically investigate the phonon transport properties of\ntopological semimetal WC and WN. The predicted room-temperature lattice thermal\nconductivities of WC (WN) along a and c directions are 1140.64 (7.47)\n$\\mathrm{W m^{-1} K^{-1}}$ and 1214.69 (5.39) $\\mathrm{W m^{-1} K^{-1}}$.\nConsidering the similar crystal structure of WC and WN, it is quite interesting\nto find that the thermal conductivity of WC is more than two orders of\nmagnitude higher than that of WN. It is found that, different from WN, the\nlarge acoustic-optical (a-o) gap prohibits the\nacoustic+acoustic$\\rightarrow$optical (aao) scattering, which gives rise to\nvery long phonon lifetimes, leading to ultrahigh lattice thermal conductivity\nin WC. For WN, the lack of a-o gap is due to soft phonon modes in optical\nbranches, which can provide more scattering channels for aao scattering,\nproducing very short phonon lifetimes. Further deep insight can be attained\nfrom their different electronic structures. Distinctly different from that in\nWC, the density of states (DOS) of WN at the Fermi level becomes very sharp,\nwhich leads to destabilization of WN, producing soft phonon modes. It is found\nthat the small shear modulus $G$ and $C_{44}$ limit the stability of WN,\ncompared with WC. Our works provide valuable information for phonon transports\nin WC and WN, and motivate further experimental works to study their lattice\nthermal conductivities."
    },
    {
        "anchor": "From Electrons to Finite Elements: A Concurrent Multiscale Approach for\n  Metals: We present a multiscale modeling approach that concurrently couples quantum\nmechanical, classical atomistic and continuum mechanics simulations in a\nunified fashion for metals. This approach is particular useful for systems\nwhere chemical interactions in a small region can affect the macroscopic\nproperties of a material. We discuss how the coupling across different scales\ncan be accomplished efficiently, and we apply the method to multiscale\nsimulations of an edge dislocation in aluminum in the absence and presence of H\nimpurities.",
        "positive": "Bond orbital description of the strain induced second order optical\n  susceptibility in silicon: We develop a theoretical model, relying on the well established sp3\nbond-orbital theory, to describe the strain-induced $\\chi^{(2)}$ in\ntetrahedrally coordinated centrosymmetric covalent crystals, like silicon. With\nthis approach we are able to describe every component of the $\\chi^{(2)}$\ntensor in terms of a linear combination of strain gradients and only two\nparameters $\\alpha$ and $\\beta$ which can be estimated theoretically. The\nresulting formula can be applied to the simulation of the strain distribution\nof a practical strained silicon device, providing an extraordinary tool for\noptimization of its optical nonlinear effects. By doing that, we were able not\nonly to confirm the main valid claims known about $\\chi^{(2)}$ in strained\nsilicon, but also estimate the order of magnitude of the $\\chi^{(2)}$ generated\nin that device."
    },
    {
        "anchor": "Room temperature skyrmions at zero field in exchange-biased ultrathin\n  films: We demonstrate that magnetic skyrmions with a mean diameter around 60 nm can\nbe stabilized at room temperature and zero external magnetic field in an\nexchange-biased Pt/Co/NiFe/IrMn multilayer stack. This is achieved through an\nadvanced optimization of the multilayer stack composition in order to balance\nthe different magnetic energies controlling the skyrmion size and stability.\nMagnetic imaging is performed both with magnetic force microscopy and scanning\nNitrogen-Vacancy magnetometry, the latter providing unambiguous measurements at\nzero external magnetic field. In such samples, we show that exchange bias\nprovides an immunity of the skyrmion spin texture to moderate external magnetic\nfield, in the tens of mT range, which is an important feature for applications\nas memory devices. These results establish exchange-biased multilayer stacks as\na promising platform towards the effective realization of memory and logic\ndevices based on magnetic skyrmions.",
        "positive": "Extension of Radiative Transfer Coherent Backscattering RT-CB code to\n  dense discrete random media: The Radiative transfer coherent backscattering (RT-CB) code is extended to\napply to dense discrete random media of optically soft spherical particles.\nThis is achieved by utilizing the well-known static-structure-factor (SSF)\ncorrection derived from the Percus-Yevick approximation for sticky-hard-sphere\n(SHS) pair correlation function. The code is verified against the numerically\nexact electromagnetic method for small spherical media consisting of\nsubmicrometer-sized icy particles at optical wavelengths. The SSF-corrected\nRT-CB method significantly improves solution accuracy, and the solution agrees\nwell with the numerically exact solution when the packing density is less than\n20% and particles are optically soft, i.e., the refractive index of particles\nis close to that of the background medium."
    },
    {
        "anchor": "Intrinsic point defects in aluminum antimonide: Calculations within density functional theory on the basis of the local\ndensity approximation are carried out to study the properties of intrinsic\npoint defects in aluminum antimonide. Special care is taken to address\nfinite-size effects, band gap error, and symmetry reduction in the defect\nstructures. The correction of the band gap is based on a set of GW\ncalculations. The most important defects are identified to be the aluminum\ninterstitial $Al_{i,Al}^{1+}$, the antimony antisites $Sb_{Al}^0$ and\n$Sb_{Al}^{1+}$, and the aluminum vacancy $V_{Al}^{3-}$. The intrinsic defect\nand charge carrier concentrations in the impurity-free material are calculated\nby self-consistently solving the charge neutrality equation. The impurity-free\nmaterial is found to be n-type conducting at finite temperatures.",
        "positive": "Metallicity in Ultra-Thin Oxygen-Deficient SrTiO$_3$ Thin Films: We report on the observation of metallic behavior in thin films of\noxygen-deficient SrTiO$_3$ - down to 9 unit cells - when coherently strained on\n(001) SrTiO$_3$ or DyScO$_3$-buffered (001) SrTiO$_3$ substrates. These films\nhave carrier concentrations of up to 2$\\times10^{22}$ cm$^{-3}$ and mobilities\nof up to 19,000 cm$^2$/V-s at 2 K. There exists a non-conducting layer in our\nSrTiO$_{3-\\delta}$ films that is larger in films with lower carrier\nconcentrations. This non-conducting layer can be attributed to a surface\ndepletion layer due to a Fermi level pinning potential. The depletion width,\ntransport, and structural properties are not greatly affected by the insertion\nof a DyScO$_3$ buffer between the SrTiO$_3$ film and SrTiO$_3$ substrate."
    },
    {
        "anchor": "Decomposition process in a FeAuPd alloy nanostructured by severe plastic\n  deformation: The decomposition process mechanisms have been investigated in a Fe50Au25Pd25\n(at.%) alloy processed by severe plastic deformation. Phases were characterized\nby X-ray diffraction and microstructures were observed using transmission\nelectron microscopy. In the coarse grain alloy homogenized and aged at $450\n^{circ}\\mathrm{C}$, the bcc \\alpha-Fe and fcc AuPd phases nucleate in the fcc\nsupersaturated solid solution and grow by a discontinuous precipitation process\nresulting in a typical lamellar structure. The grain size of the homogenized\nFeAuPd alloy was reduced in a range of 50 to 100nm by high pressure torsion.\nAging at $450 ^{circ}\\mathrm{C}$ this nanostructure leads to the decomposition\nof the solid solution into an equi-axed microstructure. The grain growth is\nvery limited during aging and the grain size remains under 100nm. The\ncombination of two phases with different crystallographic structures (bcc\n\\alpha-Fe and fcc AuPd) and of the nanoscaled grain size gives rise to a\nsignificant hardening of the alloy",
        "positive": "A Gibbs-potential-based framework for ideal plasticity of crystalline\n  solids treated as a material flow through an adjustable crystal lattice space\n  and its application to three-dimensional micropillar compression: We propose an Eulerian thermodynamically compatible model for ideal\nplasticity of crystalline solids treated as a material flow through an\nadjustable crystal lattice space. The model is based on the additive splitting\nof the velocity gradient into the crystal lattice part and the plastic part.\nThe approach extends a Gibbs-potential-based formulation developed by Rajagopal\nand Srinivasa for obtaining the response functions for elasto-visco-plastic\ncrystals. The framework makes constitutive assumptions for two scalar\nfunctions: the Gibbs potential and the rate of dissipation. The constitutive\nequations relating the stress to kinematical quantities is then determined\nusing the condition that the rate of dissipation is maximal providing that the\nrelevant constraints are met. The proposed model is applied to\nthree-dimensional micropillar compression, and its features, both on the level\nof modelling and computer simulations, are discussed and compared to relevant\nstudies."
    },
    {
        "anchor": "Domain Wall Acceleration by Ultrafast Field Application: An Ab\n  Initio-Based Molecular Dynamics Study: Optimizing ferroelectrics for contemporary high-frequency applications asks\nfor the fundamental understanding of ferroelectric switching and domain wall\n(DW) motion in ultrafast field pulses while the microscopic understanding of\nthe latter is so far incomplete. To close this gap in knowledge, ab\ninitio-based molecular dynamics simulations are utilized to analyze the\ndynamics of 180$^\\grad# DWs in the prototypical ferroelectric material BaTiO 3\n. How ultrafast field application initially excites the dipoles in the system\nand how they relax to their steady state via transient negative capacitance are\ndiscussed. Excitingly, a giant boost of the DW velocity related to the\nnonequilibrium switching of local dipoles acting as nucleation centers for the\nwall movement is found. This boost may allow to tune the local ferroelectric\nswitching rate by the shape of an applied field pulse.",
        "positive": "Revealing the origins of shear band activity and boundary strengthening\n  in polygrain-like architected materials: A recent report on successful employment of the grain boundary strengthening\nto design extraordinarily damage-tolerant architected materials (i.e.\nmeta-crystals) necessitates fundamental studies to understand the underlying\nmechanisms responsible for the toughening and high performance of\nmeta-crystals. Such understanding will enable greater confidence and control in\ndeveloping high performing and smart architected materials. In this study,\nbuckling of lattice struts in single crystal-like meta-crystals was firstly\nanalysed to reveal its role in shear band activities. Shear band systems of\nsingly oriented meta-crystals were also identified to provide a solid basis for\npredicting and controlling the shearing behaviour in polygrain-like\nmeta-crystals. The boundary-induced strengthening effects in meta-crystals was\nfound to relate to the boundary type and coherency as they govern the\ntransmission of shear bands across meta-grain boundaries. The obtained insights\nin this study provide crucial knowledge in developing high strength architected\nmaterials with great capacity in controlling the mechanical strength and damage\npath."
    },
    {
        "anchor": "Machine Learning and Evolutionary Prediction of Superhard B-C-N\n  Compounds: We build random forests models to predict elastic properties and mechanical\nhardness of a compound, using only its chemical formula as input. The model\ntraining uses over 10,000 target compounds and 60 features based on\nstoichiometric attributes, elemental properties, orbital occupations, and ionic\nbonding levels. Using the models, we construct triangular graphs for B-C-N\ncompounds to map out their bulk and shear moduli, as well as hardness values.\nThe graphs indicate that a 1:1 B-N ratio can lead to various superhard\ncompositions. We also validate the machine learning results by evolutionary\nstructure prediction and density functional theory. Our study shows that\nBC$_{10}$N, B$_4$C$_5$N$_3$, and B$_2$C$_3$N exhibit dynamically stable phases\nwith hardness values $>40$GPa, which are potentially new superhard materials\nthat could be synthesized by low-temperature plasma methods.",
        "positive": "Comparative modeling studies of TSDC: investigation of Alpha-relaxation\n  in Amorphous polymers: A model to investigate Thermally Stimulated Depolarization Current (TSDC)\npeak parameters using the dipole-dipole interaction concept is proposed by the\nauthor in this work. The proposed model describe the (TSDC) peak successfully\nsince it gives a significant peak parameters (i.e. Activation energy (E) and\nthe per-exponential factor (\\tau_0) in addition to the dipole-dipole\ninteraction strength parameter (di). Application of this model to determine the\npeak parameters of polyvinyl chloride(PVC) polymer is presented . The results\nshow how the model fit the experimental thermal sampling data. Finally the\nresults are compared to the well know techniques; the initial rise method (IR),\nthe half width method (HW) in addition to the Cowell and Woods analysis."
    },
    {
        "anchor": "Existence of vertical spin stiffness in Landau-Lifshitz-Gilbert equation\n  in ferromagnetic semiconductors: We calculate the magnetization torque due to the spin polarization of the\nitinerant electrons by deriving the kinetic spin Bloch equations based on the\n$s$-$d$ model. We find that the first-order gradient of the magnetization\ninhomogeneity gives rise to the current-induced torques, which are consistent\nto the previous works. At the second-order gradient, we find an effective\nmagnetic field perpendicular to the spin stiffness filed. This field is\nproportional to the nonadiabatic parameter $\\beta$. We show that this vertical\nspin stiffness term can significantly modify the domain-wall structure in\nferromagnetic semiconductors and hence should be included in the\nLandau-Lifshitz-Gilbert equation in studying the magnetization dynamics.",
        "positive": "Room temperature propylene dehydrogenation and linear atomic chain\n  formation on Ni(111): The structures formed by propylene adsorption on Ni(111) at room temperature\nare determined by a combination of scanning tunneling microscopy and density\nfunctional theory. As a result of the interaction with the Ni(111) surface,\npropylene molecules are dehydrogenated and coupled into linear hydrocarbon\nchains. The length of the chains varies from 8 to 60A, with the most frequently\nobserved length of 18A. At saturated coverage, some chains are closed in rings\nwith a diameter of 6A. A C12H12 model is proposed for most often observed\nchains. We demonstrate that the possibility of combining initial propylene\nmolecules into chains appears after dehydrogenation of the CH3 fragment."
    },
    {
        "anchor": "The monoclinic phase in PZT: new light on morphotropic phase boundaries: A summary of the work recently carried out on the morphotropic phase boundary\n(MPB) of PZT is presented. By means of x-ray powder diffraction on ceramic\nsamples of excellent quality, the MPB has been successfully characterized by\nchanging temperature in a series of closely spaced compositions. As a result,\nan unexpected monoclinic phase has been found to exist in between the\nwell-known tetragonal and rhombohedral PZT phases. A detailed structural\nanalysis, together with the investigation of the field effect in this region of\ncompositions, have led to an important advance in understanding the mechanisms\nresponsible for the physical properties of PZT as well as other piezoelectric\nmaterials with similar morphotropic phase boundaries.",
        "positive": "Phase Transition of Two-Dimensional Ferroelectric and Paraelectric Ga2O3\n  Monolayer: A Density Functional Theory and Machine-Learning Study: Ga2O3 is a wide-band-gap semiconductor of great interest for applications in\nelectronics and optoelectronics. Two-dimensional (2D) Ga2O3 synthesized from\ntop-down or bottom-up processes can reveal brand new heterogeneous structures\nand promising applications. In this paper, we study phase transitions among\nthree low-energy stable Ga2O3 monolayer configurations using density functional\ntheory and a newly developed machine-learning Gaussian approximation potential,\ntogether with solid-state nudged elastic band calculations. Kinetic minimum\nenergy paths involving direct atomic jump as well as concerted layer motion are\ninvestigated. The low phase transition barriers indicate feasible tunability of\nthe phase transition and orientation via strain engineering and external\nelectric fields. Large-scale calculations using the newly trained\nmachine-learning potential on the thermally activated single-atom jumps reveal\nthe clear nucleation and growth processes of different domains. The results\nprovide useful insights to future experimental synthesis and characterization\nof 2D Ga2O3 monolayers."
    },
    {
        "anchor": "Field emission from single multi-wall carbon nanotubes: Electron field emission characteristics of individual multiwalled carbon\nnanotubes have been investigated by a piezoelectric nanomanipulation system\noperating inside a scanning electron microscopy chamber. The experimental setup\nensures a high control capability on the geometric parameters of the field\nemission system (CNT length, diameter and anode-cathode distance). For several\nmultiwalled carbon nanotubes, reproducible and quite stable emission current\nbehaviour has been obtained with a dependence on the applied voltage well\ndescribed by a series resistance modified Fowler-Nordheim model. A turn-on\nfield of about 30 V/um and a field enhancement factor of around 100 at a\ncathode-anode distance of the order of 1 um have been evaluated. Finally, the\neffect of selective electron beam irradiation on the nanotube field emission\ncapabilities has been extensively investigated.",
        "positive": "Electronic Evidence for Type II Weyl Semimetal State in MoTe2: Topological quantum materials, including topological insulators and\nsuperconductors, Dirac semimetals and Weyl semimetals, have attracted much\nattention recently for their unique electronic structure, spin texture and\nphysical properties. Very lately, a new type of Weyl semimetals has been\nproposed where the Weyl Fermions emerge at the boundary between electron and\nhole pockets in a new phase of matter, which is distinct from the standard type\nI Weyl semimetals with a point-like Fermi surface. The Weyl cone in this type\nII semimetals is strongly tilted and the related Fermi surface undergos a\nLifshitz transition, giving rise to a new kind of chiral anomaly and other new\nphysics. MoTe2 is proposed to be a candidate of a type II Weyl semimetal; the\nsensitivity of its topological state to lattice constants and correlation also\nmakes it an ideal platform to explore possible topological phase transitions.\nBy performing laser-based angle-resolved photoemission (ARPES) measurements\nwith unprecedentedly high resolution, we have uncovered electronic evidence of\ntype II semimetal state in MoTe2. We have established a full picture of the\nbulk electronic states and surface state for MoTe2 that are consistent with the\nband structure calculations. A single branch of surface state is identified\nthat connects bulk hole pockets and bulk electron pockets. Detailed\ntemperature-dependent ARPES measurements show high intensity spot-like features\nthat is ~40 meV above the Fermi level and is close to the momentum space\nconsistent with the theoretical expectation of the type II Weyl points. Our\nresults constitute electronic evidence on the nature of the Weyl semimetal\nstate that favors the presence of two sets of type II Weyl points in MoTe2."
    },
    {
        "anchor": "Tuning the Intrinsic Spin Hall Effect by Charge Density Wave Order in\n  Topological Kagome Metals: Kagome metals are topological materials with a rich phase diagram featuring\nvarious charge density wave orders and even unconventional superconductivity.\nHowever, little is still known about possible spin-polarized responses in these\nnon-magnetic compounds. Here, we perform ab-initio calculations of the\nintrinsic spin Hall effect (SHE) in the kagome metals AV$_3$Sb$_5$ (A=Cs, Rb,\nK), CsTi$_3$Bi$_5$ and ScV$_6$Sn$_6$. We report large spin Hall conductivities,\ncomparable with the Weyl semimetal TaAs. Additionally, in CsV$_3$Sb$_5$ the SHE\nis strongly renormalized by the CDW order. We can understand these results\nbased on the topological properties of band structures, demonstrating that the\nSHE is dominated by the position and shape of the Dirac nodal lines in the\nkagome sublattice. Our results suggest kagome materials as a promising, tunable\nplatform for future spintronics applications.",
        "positive": "Topological Descriptors Help Predict Guest Adsorption in Nanoporous\n  Materials: Machine learning has emerged as an attractive alternative to experiments and\nsimulations for predicting material properties. Usually, such an approach\nrelies on specific domain knowledge for feature design: each learning target\nrequires careful selection of features that an expert recognizes as important\nfor the specific task. The major drawback of this approach is that computation\nof only a few structural features has been implemented so far, and it is\ndifficult to tell a priori which features are important for a particular\napplication. The latter problem has been empirically observed for predictors of\nguest uptake in nanoporous materials: local and global porosity features become\ndominant descriptors at low and high pressures, respectively. We investigate a\nfeature representation of materials using tools from topological data analysis.\nSpecifically, we use persistent homology to describe the geometry of nanoporous\nmaterials at various scales. We combine our topological descriptor with\ntraditional structural features and investigate the relative importance of each\nto the prediction tasks. We demonstrate an application of this feature\nrepresentation by predicting methane adsorption in zeolites, for pressures in\nthe range of 1-200 bar. Our results not only show a considerable improvement\ncompared to the baseline, but they also highlight that topological features\ncapture information complementary to the structural features: this is\nespecially important for the adsorption at low pressure, a task particularly\ndifficult for the traditional features. Furthermore, by investigation of the\nimportance of individual topological features in the adsorption model, we are\nable to pinpoint the location of the pores that correlate best to adsorption at\ndifferent pressure, contributing to our atom-level understanding of\nstructure-property relationships."
    },
    {
        "anchor": "Electronic and magnetic properties of the (111) surfaces of NiMnSb: Using an ab-initio electronic structure method, I study the (111) surfaces of\nthe half-metallic NiMnSb alloy. In all cases there is a very pronounced surface\nstate within the minority gap which destroys the half-metallicity This state\nsurvives for several atomic layers below the surface contrary to the (001)\nsurfaces where surface states were located only at the surface layer. The lower\ndimensionality of the surface leads in general to large enhancements of the\nsurface spin moments.",
        "positive": "The anti-symmetric and anisotropic symmetric exchange interactions\n  between electric dipoles in hafnia: The anti-symmetric and anisotropic symmetric exchange interactions between\ntwo magnetic dipole moments - responsible for intriguing magnetic textures\n(e.g., magnetic skyrmions) - have been discovered since last century, while\ntheir electric analogues were either hidden for a long time or still not known.\nAs a matter of fact, it is only recently that the anti-symmetric exchange\ninteractions between electric dipoles was proved to exist (with materials\nhosting such an interaction being still rare) and the existence of anisotropic\nsymmetric exchange interaction between electric dipoles remains to be revealed.\nHere, by symmetry analysis and first-principles calculations, we identify a\ncandidate material in which our aforementioned exchange interactions between\nelectric dipoles are perceptible. More precisely, we find that various phases\nof hafnia showcase non-collinear alignment of electric dipoles, which is\ninterpreted by our phenomenological theories. This gives evidence that hafnia\nsimultaneously accommodates anti-symmetric and anisotropic symmetric exchange\ninteractions between electric dipoles. Our findings can hopefully deepen the\ncurrent knowledge of electromagnetism in ferroelectrics, magnets and\nmultiferroics, and have a potential to guide the discovery of novel states of\nmatter (e.g., electric skyrmions) in hafnia and related materials."
    },
    {
        "anchor": "Coupled Electron-Ion Monte Carlo simulation of hydrogen molecular\n  crystals: We performed simulations for solid molecular hydrogen at high pressures\n(250GPa$\\leq$P$\\leq$500GPa) along two isotherms at T=200 K (phases III and VI)\nand at T=414 K (phase IV). At T=200K we considered likely candidates for phase\nIII, the C2c and Cmca12 structures, while at T=414K in phase IV we studied the\nPc48 structure. We employed both Coupled Electron-Ion Monte Carlo (CEIMC) and\nPath Integral Molecular Dynamics (PIMD) based on Density Functional Theory\n(DFT) using the vdW-DF approximation. The comparison between the two methods\nallows us to address the question of the accuracy of the xc approximation of\nDFT for thermal and quantum protons without recurring to perturbation theories.\nIn general, we find that atomic and molecular fluctuations in PIMD are larger\nthan in CEIMC which suggests that the potential energy surface from vdW-DF is\nless structured than the one from Quantum Monte Carlo. We find qualitatively\ndifferent behaviors for systems prepared in the C2c structure for increasing\npressure. Within PIMD the C2c structure is dynamically partially stable for\nP$\\leq$250GPa only: it retains the symmetry of the molecular centers but not\nthe molecular orientation; at intermediate pressures it develops layered\nstructures like Pbcn or Ibam and transforms to the metallic Cmca-4 structure at\nP$\\geq$450GPa. Instead, within CEIMC, the C2c structure is found to be\ndynamically stable at least up to 450GPa; at increasing pressure the molecular\nbond length increases and the nuclear correlation decreases. For the other two\nstructures the two methods are in qualitative agreement although quantitative\ndifferences remain. We discuss various structural properties and the electrical\nconductivity. We find these structures become conducting around 350GPa but the\nmetallic Drude-like behavior is reached only at around 500GPa, consistent with\nrecent experimental claims.",
        "positive": "Theory for the ultrafast ablation of graphite films: The physical mechanisms for damage formation in graphite films induced by\nfemtosecond laser pulses are analyzed using a microscopic electronic theory. We\ndescribe the nonequilibrium dynamics of electrons and lattice by performing\nmolecular dynamics simulations on time-dependent potential energy surfaces. We\nshow that graphite has the unique property of exhibiting two distinct laser\ninduced structural instabilities. For high absorbed energies (> 3.3 eV/atom) we\nfind nonequilibrium melting followed by fast evaporation. For low intensities\nabove the damage threshold (> 2.0 eV/atom) ablation occurs via removal of\nintact graphite sheets."
    },
    {
        "anchor": "Temperature dependence and quenching characteristics of (La,\n  Gd)$_2$Si$_2$O$_7$ scintillators at various Ce concentrations: We investigated the thermal stability of scintillation and the luminescence\nperformances of (La, Gd)${}_{2}$Si${}_{2}$O${}_{7}$ single crystals at various\nCe concentrations. We prepared (La${}_{0.25-x}$, Ce${}_{x}$,\nGd${}_{0.75}$)${}_{2}$Si${}_{2}$O${}_{7}$ (x = 0.0001, 0.001, 0.005, 0.01,\n0.02, 0.05, and 0.1; unit: molar concentration) single crystals by the\nCzochralski and micro-pulling-down methods. With increasing Ce concentration,\nthe photoluminescence emission and photoluminescence excitation spectral bands\nshifted to low energies and the activation energy $\\mathrm{\\Delta }E$ for\nthermal quenching decreased. For Ce $\\mathrm{<}$ 0.5 at.% samples, the\nphotoluminescence emission background value calculated in the exponential\napproximation started to increase at temperatures greater than 320 K, which is\nprobably because of Ce${}^{3+}$ 5$\\textit{d}$ excited-state ionization.\nHowever, the effect was weaker for the Ce $\\ge $ 0.5% samples, which may\nindicate a comparatively larger contribution from other nonradiative\nrelaxations. Thus the main reason for the thermal quenching of the Ce${}^{3+}$\nemission in (La, Gd)${}_{2}$Si${}_{2}$O${}_{7}$ is the combination of the\n5$\\textit{d}$1 excited-state ionization and nonradiative relaxation via\nthermally excited crossover from the 5$\\textit{d}$ excited state to the\n4$\\textit{f}$ ground state. The temperature dependence of the scintillation\nlight yield was similar irrespective of the Ce concentration, with Ce 1.0%\nexhibiting the best performance within the temperature range 300 K to 450 K.",
        "positive": "Direct visualization of magnetic correlations in frustrated spinel\n  ZnFe$_2$O$_4$: Magnetic materials with the spinel structure (A$^{2+}$B$^{3+}_2$O$^4$) form\nthe core of numerous magnetic devices, but ZnFe$_2$O$_4$ constitutes a peculiar\nexample where the nature of the magnetism is still unresolved. Susceptibility\nmeasurements revealed a cusp around $T_c=13\\;\\mathrm{K}$ resembling an\nantiferromagnetic transition, despite the positive Curie-Weiss temperature\ndetermined to be $\\Theta_{CW}=102.8(1)\\;\\mathrm{K}$. Bifurcation of\nfield-cooled and zero-field-cooled data below $T_c$ in conjunction with a\nfrequency dependence of the peak position and a non-zero imaginary component\nbelow $T_c$ shows it is in fact associated with a spin-glass transition. Highly\nstructured magnetic diffuse neutron scattering from single crystals develops\nbetween $50\\;\\mathrm{K}$ and $25\\;\\mathrm{K}$ revealing the presence of\nmagnetic disorder which is correlated in nature. Here, the 3D-m$\\Delta$PDF\nmethod is used to visualize the local magnetic ordering preferences, and\nferromagnetic nearest-neighbor and antiferromagnetic third nearest-neighbor\ncorrelations are shown to be dominant. Their temperature dependence is\nextraordinary with some flipping in sign, and a strongly varying correlation\nlength. The correlations can be explained by orbital interaction mechanisms for\nthe magnetic pathways, and a preferred spin cluster. Our study demonstrates the\npower of the 3D-m$\\Delta$PDF method in visualizing complex quantum phenomena\nthereby providing a way to obtain an atomic scale understanding of magnetic\nfrustration."
    },
    {
        "anchor": "Optical Response of Solid CO$_2$ as a Tool for the Determination of the\n  High Pressure Phase: We report first-principles calculations of the frequency dependent linear and\nsecond-order optical properties of the two probable extended-solid phases of\nCO$_2$--V, i.e. $I\\bar42d$ and $P2_12_12_1$. Compared to the parent $Cmca$\nphase the linear optical susceptibility of both phases is much smaller. We find\nthat $I\\bar42d$ and $P2_12_12_1$ differ substantially in their linear optical\nresponse in the higher energy regime. The nonlinear optical responses of the\ntwo possible crystal structures differ by roughly a factor of five. Since the\ndifferences in the nonlinear optical spectra are pronounced in the low energy\nregime, i.e. below the band gap of diamond, measurements with the sample inside\nthe diamond anvil cell are feasible. We therefore suggest optical experiments\nin comparison with our calculated data as a tool for the unambiguous\nidentification of the high pressure phase of CO$_2$.",
        "positive": "Decagonal Sn clathrate on $d$-Al-Ni-Co: Decagonal quasiperiodic ordering of Sn thin film on $d$-Al-Ni-Co, is shown\nbased on scanning tunneling microscopy (STM), low-energy electron diffraction\nand density functional theory (DFT). Interestingly, the decagonal structural\ncorrelations are partially retained up to a large film thickness of 10 nm grown\nat a 165$\\pm$10 K. The nucleation centers called 'Sn white flowers' identified\nby STM at submonolayer thickness are recognized as valid patches of the\ndecagonal clathrate structure with low adsorption energies. Due to the\nexcellent lattice matching (to within 1%) between columns of Sn dodecahedra in\nthe clathrate structure and pentagonal motifs at the $d$-Al-Ni-Co surface, the\ninterfacial energy favors clathrate over the competing Sn crystalline forms.\nDFT study of the Sn/Al-Ni-Co composite model shows good mechanical stability,\nas shown by the work of separation of Sn from Al-Ni-Co slab that is comparable\nto clathrate self-separation energy. The relaxed surface terminations of the\nR$_2$T$_4$ clathrate approximant are in self-similarity correspondence with the\nmotifs observed in the STM images from monolayer to thickest Sn film."
    },
    {
        "anchor": "Effects of polarization on the band-structure of delafossite transparent\n  conductive oxides: We use hybrid functionals and restricted self-consistent GW, state-of-the-art\ntheoretical approaches for quasiparticle band structures, to study the\nelectronic states of delafossite Cu(Al,In)O$_2$, the first p-type and bipolar\ntransparent conductive oxides. We show that self-consistent GW gives remarkably\nwider band gaps than all the other approaches used so far. Accounting for\npolaronic effects in the GW scheme we recover a very nice agreement with\nexperiments. Furthermore, the modifications with respect to the Kohn-Sham bands\nare strongly k-dependent, which makes questionable the common practice of using\na scissor operator. Finally, our results support the view that the low energy\nstructures found in optical experiments, and initially attributed to an\nindirect transition, are due to intrinsic defects in the samples.",
        "positive": "High temperature dielectric and impedance spectroscopy study of\n  LaCo$_{0.7}$Nb$_{0.3}$O$_3$: We report the high temperature dielectric and {\\it ac} impedance spectroscopy\ninvestigation of Nb substituted LaCo$_{0.7}$Nb$_{0.3}$O$_3$ polycrystalline\nsample. The maximum dielectric constant value was observed $\\approx$1400 at\naround 400~K where the peak value shows a decreasing trend at higher\ntemperatures and frequency. Similar variation was reflected in the dielectric\nloss (tan$\\delta$) behavior with temperature, which shows the thermal\nactivation of the charge carriers in the material. The analysis of high\ntemperature impedance spectroscopy data shows the grain and grain boundary\ncontributions by fitting the Nyquist plots to the equivalent circuit. From the\nanalysis of the impedance and modulus spectra, it was possible to discern\nbetween the effects of overlapping grains, grain boundaries, and electrode\ninterfaces. The relaxation time decreases with an increase in the temperature\nand the activation energy changes from 0.44~eV to 0.56~eV at around 400~K,\nwhich is due to involvement of thermal activation in the conduction of charge\ncarriers. The conductivity is found to be increased with temperature for a\ngiven frequency, which again shows the semiconducting behavior. Whereas the\nconductivity increases with increase in frequency at lower temperatures. Also,\nthe conductivity almost saturates with frequency at high temperatures."
    },
    {
        "anchor": "Planar carbon nanotube-graphene hybrid films for high-performance\n  broadband photodetectors: Graphene has emerged as a promising material for photonic applications\nfuelled by its superior electronic and optical properties. However, the\nphotoresponsivity is limited by the low absorption cross section and ultrafast\nrecombination rates of photoexcited carriers. Here we demonstrate a\nphotoconductive gain of $\\sim$ 10$^5$ electrons per photon in a carbon\nnanotube-graphene one dimensional-two dimensional hybrid due to efficient\nphotocarriers generation and transport within the nanostructure. A broadband\nphotodetector (covering 400 nm to 1550 nm) based on such hybrid films is\nfabricated with a high photoresponsivity of more than 100 AW$^{-1}$ and a fast\nresponse time of approximately 100 {\\mu}s. The combination of ultra-broad\nbandwidth, high responsivities and fast operating speeds affords new\nopportunities for facile and scalable fabrication of all-carbon optoelectronic\ndevices.",
        "positive": "Topological Spectral Bands with Frieze Groups: Frieze groups are discrete subgroups of the full group of isometries of a\nflat strip. We investigate here the dynamics of specific architected materials\ngenerated by acting with a frieze group on a collection of self-coupling seed\nresonators. We demonstrate that, under unrestricted reconfigurations of the\ninternal structures of the seed resonators, the dynamical matrices of the\nmaterials generate the full self-adjoint sector of the stabilized group\n$C^\\ast$-algebra of the frieze group. As a consequence, in applications where\nthe positions, orientations and internal structures of the seed resonators are\nadiabatically modified, the spectral bands of the dynamical matrices carry a\ncomplete set of topological invariants that are fully accounted by the K-theory\nof the mentioned algebra. By resolving the generators of the K-theory, we\nproduce the model dynamical matrices that carry the elementary topological\ncharges, which we implement with systems of plate resonators to showcase\nseveral applications in spectral engineering. The paper is written in an\nexpository style."
    },
    {
        "anchor": "Evidence for a New Family of 2-D Honeycomb Surface Reconstructions on\n  Si(111): A new silicene-like family of reconstructed surfaces on Si111 are discussed\nwhich appears to be a polymorph to the well know family of surface\nreconstructions best epitomized by the 7x7 surface. Several experimental\nfeatures are discussed which lead to this new conclusion, as are several\nrecently established limitations of density functional theory that may\ncurrently limit its ability to predict such 2-D surface structures. The atomic\nlocations of the surface state charge densities from several Scanning Tunneling\nSpectroscopy studies provide the basis for this new structure which is\nsupported by several previous measurements. The new structure appears to favor\na faulted supercell honeycomb motif having a delocalized 2-D state that enables\ngreater sp2 character. This top layer has an unusual periodic pi-orbital\nstructure that also interdigitates with the terminal bulk 'dangling bonds' to\ncreate a 2-D pi-bonded structure. This new polymorphic structure resolves many\nlong standing paradoxes of the 7x7 surface while its unusual bonding and\nstructure may help better understand some silicenes as well as the behavior of\nother 2-D phases on 111 surfaces.",
        "positive": "Localized chemical switching of the charge state of nitrogen-vacancy\n  luminescence centers in diamond: We present a beam-directed chemical technique for controlling the charge\nstates of near-surface luminescence centers in semiconductors. Specifically, we\nfluorinate the surface of H-terminated diamond by electron beam irradiation in\nthe presence of NF3 vapor. The fluorination treatment acts as a local chemical\nswitch that alters the charge state of nitrogen-vacancy luminescence centers\nfrom the neutral to the negative state. The electron beam fluorination process\nis highly localized and can be used to control the emission spectrum of\nindividual nanodiamonds and surface regions scanned by the electron beam"
    },
    {
        "anchor": "Facile and fast growth of high mobility nanoribbons of ZrTe$_5$: Recently, ZrTe$_5$ has received a lot of attention as it exhibits various\ntopological phases, such as weak and strong topological insulators, a Dirac\nsemimetal, and a quantum spin Hall insulator in the monolayer limit. While most\nof studies have been focused on the three-dimensional bulk material, it is\nhighly desired to obtain nanostructured materials due to their advantages in\ndevice applications. We report the synthesis and characterizations of ZrTe$_5$\nnanoribbons. Via a silicon-assisted chemical vapor transport method, long\nnanoribbons with thickness as thin as 20 nm can be grown. The growth rate is\nover an order of magnitude faster than the previous method for growth of bulk\ncrystals. Moreover, transport studies show that nanoribbons are of low\nunintentional doping and high carrier mobility, over 30,000 cm$^2$/Vs, which\nenable reliable determination of the Berry phase of $\\pi$ in the $ac$ plane\nfrom quantum oscillations. Our method holds great potential in growth of high\nquality ultra-thin nanostructures of ZrTe$_5$.",
        "positive": "Exploring dynamical magnetism with time-dependent density-functional\n  theory: from spin fluctuations to Gilbert damping: We use time-dependent spin-density-functional theory to study dynamical\nmagnetic phenomena. First, we recall that the local-spin-density approximation\n(LSDA) fails to account correctly for magnetic fluctuations in the paramagnetic\nstate of iron and other itinerant ferromagnets. Next, we construct a\ngradient-dependent density functional that does not suffer from this problem of\nthe LSDA. This functional is then used to derive, for the first time, the\nphenomenological Gilbert equation of micromagnetics directly from\ntime-dependent density-functional theory. Limitations and extensions of Gilbert\ndamping are discussed on this basis, and some comparisons with phenomenological\ntheories and experiments are made."
    },
    {
        "anchor": "Incommensurate magnetism in K$_2$MnS$_{2-x}$Se$_x$ and prospects for\n  tunable frustration in a triangular lattice of pseudo-1D spin chains: We report the first detailed investigation of K$_2$MnS$_2$ and K$_2$MnSe$_2$\nfrom the K$_2$MnS$_2$ structure type and their magnetic solid solution\nK$_2$MnS$_{2-x}$Se$_x$ and find that compounds of this structure type consist\nof strongly-coupled pseudo-one-dimensional antiferromagnetic chains that\ncollectively represent a frustrated two-dimensional triangular antiferromagnet.\nBulk samples of K$_2$MnS$_{2-x}$Se$_x$ with $0 \\leq x \\leq 2$ are characterized\nusing X-ray diffraction, neutron diffraction, magnetization and heat capacity\nmeasurements. An incommensurate cycloid magnetic structure with a magnetic\npropagation vector $k = [0.58~0~1]$ is observed for all samples in\nK$_2$MnS$_{2-x}$Se$_x$, and the ordering is robust despite a 12\\% increase in\ncell volume. Geometric frustration of chains results in incommensurability\nalong $a$ and a two-step magnetic transition. The varying geometries accessible\nin compounds of this structure type are presented as promising avenues to tune\nfrustration.",
        "positive": "Electrical switching of vortex core in a magnetic disk: A magnetic vortex is a curling magnetic structure realized in a ferromagnetic\ndisk, which is a promising candidate of a memory cell for future nonvolatile\ndata storage devices. Thus, understanding of the stability and dynamical\nbehaviour of the magnetic vortex is a major requirement for developing magnetic\ndata storage technology. Since the experimental proof of the existence of a\nnanometre-scale core with out-of-plane magnetisation in the magnetic vortex,\nthe dynamics of a vortex has been investigated intensively. However, the way to\nelectrically control the core magnetisation, which is a key for constructing a\nvortex core memory, has been lacking. Here, we demonstrate the electrical\nswitching of the core magnetisation by utilizing the current-driven resonant\ndynamics of the vortex; the core switching is triggered by a strong dynamic\nfield which is produced locally by a rotational core motion at a high speed of\nseveral hundred m/s. Efficient switching of the vortex core without magnetic\nfield application is achieved thanks to resonance. This opens up the\npotentiality of a simple magnetic disk as a building block for spintronic\ndevices like a memory cell where the bit data is stored as the direction of the\nnanometre-scale core magnetisation."
    },
    {
        "anchor": "Tool steel ion beam assisted nitrocarburization: The nitrocarburization of the AISI-H13 tool steel by ion beam assisted\ndeposition is reported. In this technique, a carbon film is continuously\ndeposited over the sample by the ion beam sputtering of a carbon target while a\nsecond ion source is used to bombard the sample with low energy nitrogen ions.\nThe results show that the presence of carbon has an important impact on the\ncrystalline and microstructural properties of the material without modification\nof the case depth.",
        "positive": "Crystal Chemistry at High Pressure: An overview of the behavior of materials at high pressure is presented,\nstarting from the effects on single atoms driving electronic transitions and\nchanges in periodic trends. A range of high-pressure-induced phenomena in the\nsolid state are then discussed building on the atomic changes, including\nbizarre electronic structures, electrides, compounds of noble gases, changes in\nelemental miscibility, and strange structural and bonding configurations. In\nthe final section, the field of high pressure superconductivity is discussed,\nas high pressure phases have generated immense study and excitement as some of\ntheir critical superconducting temperatures approach room temperature."
    },
    {
        "anchor": "Single-domain perpendicular magnetization induced by the coherent O\n  2p-Ru 4d hybridized state in an ultra-high-quality SrRuO3 film: We investigated the Ru 4d and O 2p electronic structure and magnetic\nproperties of an ultra-high-quality SrRuO3 film on SrTiO3 grown by\nmachine-learning-assisted molecular beam epitaxy. The high itinerancy and long\nquantum lifetimes of the quasiparticles in the Ru 4d t2g-O 2p hybridized\nvalence band are confirmed by observing the prominent well-screened peak in the\nRu 3d core-level photoemission spectrum, the coherent peak near the Fermi\nenergy in the valence band spectrum, and quantum oscillations in the\nresistivity. The element-specific magnetic properties and the hybridization\nbetween the Ru 4d and O 2p orbitals were characterized by Ru M2,3-edge and O\nK-edge soft X-ray absorption spectroscopy and X-ray magnetic circular dichroism\nmeasurements. The ultra-high-quality SrRuO3 film with the residual resistivity\nratio of 86 shows the large orbital magnetic moment of oxygen ions induced by\nthe strong orbital hybridization of the O 2p states with the spin-polarized Ru\n4d t2g states. The film also shows single-domain perpendicular magnetization\nwith an almost ideal remanent magnetization ratio of 0.97. These results\nprovide detailed insights into the relevance between orbital hybridization and\nthe perpendicular magnetic anisotropy in SrRuO3/SrTiO3 systems.",
        "positive": "Spin-entropy contribution to thermopower in the\n  [Ca$_2$CoO$_{3-t}$]$_{0.62}$(CoO$_2$) misfits: Two samples of the [Ca$_2$CoO$_{3-t}$]$_{0.62}$(CoO$_2$) misfit cobaltate,\noften denoted as the Ca$_{3}$Co$_{3.93}$O$_{9}$ phase, were prepared from the\nsame ceramic material by the oxygen and argon annealing, resulting in different\ncarrier concentrations in the conducting CoO$_{2}$ layers, n=0.31 and 0.19\nhole/Co, respectively. Electrical and thermal transport properties were studied\nin dependence of magnetic field up to 140 kOe. The magnetothermopower data\nreveal an extra spin-entropy contribution to Seebeck coefficient that is not\nexpected for carriers of Fermi liquid character. Its magnitude is\nunprecedentedly large and makes at zero field up to 50$\\%$ of the theoretical\nlimit k$_B$/$e$ ln2$ = 59 \\mu VK^{-1}$. This spin-entropy contribution is\ngradually suppressed with increasing magnetic field, and the saturation is even\nobserved when temperatures are low enough. To understand the results, the\nthermopower is treated in terms of purely thermodynamic Kelvin formula, and\nso-called Spin liquid model is evoked, providing a reason for the spin-entropy\nmanifestation in the [Ca$_2$CoO$_{3-t}$]$_{0.62}$(CoO$_2$) misfits."
    },
    {
        "anchor": "Pressure-tuning of the electron-phonon coupling: the insulator to metal\n  transition in manganites: A comprehensive understanding of the physical origin of the unique magnetic\nand transport properties of A_(1-x)A'^xMnO_3 manganites (A = trivalent\nrare-earth and A' = divalent alkali-earth metal) is still far from being\nachieved. The complexity of these systems arises from the interplay among\nseveral competing interactions of comparable strength. Recently the\nelectron-phonon coupling, triggered by a Jahn-Teller distortion of the MnO_6\noctahedra, has been recognised to play an essential role in the insulator to\nmetal transition and in the closely related colossal magneto-resistance. The\npressure tuning of the octahedral distortion gives a unique possibility to\nseparate the basic interactions and, at least in principle, to follow the\nprogressive transformation of a manganite from an intermediate towards a weak\nelectron-phonon coupling regime. Using a diamond anvil cell, temperature and\npressure-dependent infrared absorption spectra of La_(0.75)Ca_(0.25)MnO_3 have\nbeen collected and, from the spectral weight analysis, the pressure dependence\nof the insulator to metal transition temperature T_IM has been determined for\nthe first time up to 11.2 GPa. The T_IM(P) curve we proposed to model the\npresent data revealed a universality character in accounting for the whole\nclass of intermediate coupling compounds. This property can be exploited to\ndistinguish the intermediate from the weak coupling compounds pointing out the\nfundamental differences between the two coupling regimes.",
        "positive": "The underestimation of high pressure in DFT+$U$ simulation for the wide\n  range cold-pressure of lanthanide metals: Density functional theory plus $U$ (DFT+$U$) is one of the most efficient\nfirst-principles methods to simulate the cold pressure properties of\nstrongly-correlated materials. However, the applicability of DFT+$U$ at\nultra-high pressure is not sufficiently studied, especially in the widely-used\naugmented schemes [such as projector augmented wave (PAW) and linearized\naugmented plane wave (LAPW)]. This work has systematically investigated the\nperformance of DFT+$U$ in PAW and LAPW at the pressure up to several hundred\nGPa for the lanthanide metals, which is a typical strongly-correlated series.\nWe found DFT+$U$ simulation in PAW exhibits an unphysical underestimating of\nforce at high pressure. By delicate analysis and comparison with\nlocal-orbital-independent hybrid functional results, we have demonstrated that\nthis unphysical behavior is related to a normalization problem on the local\ndensity matrix caused by the overlap of local orbitals in PAW under high\npressure. Additionally, we observed a slight softening of force in DFT+$U$ in\nheavy lanthanides (Tm, Yb and Lu) at high pressure comparing with the DFT\nresults without the influence of local orbital overlap, and it might be related\nto the enhancement of bonding effect in correlation correction methods at high\npressure. Our work reveals the underestimating of high pressure in DFT+$U$\nsimulation, analyses two sources of this unusual behavior and proposes their\nmechanism. Most importantly, our investigation highlights the breakdown of\nDFT+$U$ for high pressure simulation in VASP package based on PAW framework."
    },
    {
        "anchor": "Microwave non-reciprocity of magnon excitations in a non-centrosymmetric\n  antiferromagnet Ba$_2$MnGe$_2$O$_7$: We have investigated the microwave non-reciprocity for a non-centrosymmetric\nantiferromagnet Ba$_2$MnGe$_2$O$_7$. The magnon modes expected by the\nconventional spin wave theory for staggered antiferromagnets are certainly\nobserved. The magnitudes of exchange interaction and magnetic anisotropy are\nobtained by the comparison with the theory. The microwave non-reciprocity is\nidentified for one of these mode. The relative magnitude of microwave\nnon-reciprocity can be explained with use of spin wave theory and Kubo formula.",
        "positive": "Spectroscopic Characterization of Gapped Graphene in the Presence of\n  Circularly Polarized Light: We present a description of the energy loss of a charged particle moving\nparallel to a graphene layer and graphene double layers. Specifically, we\ncompare the stopping power of the plasma oscillations for these two\nconfigurations in the absence as well as the presence of circularly polarized\nlight whose frequency and intensity can be varied to yield an energy gap of\nseveral hundred $\\texttt{meV}$ between the valence and conduction bands. The\ndressed states of the Dirac electrons by the photons yield collective plasma\nexcitations whose characteristics are qualitatively and quantitatively\ndifferent from those produced by Dirac fermions in gapless graphene, due in\npart to the finite effective mass of the dressed electrons. For example, the\nrange of wave numbers for undamped self-sustaining plasmons is increased as the\ngap is increased, thereby increasing the stopping power of graphene for some\nrange of charged particle velocity when graphene is radiated by circularly\npolarized light."
    },
    {
        "anchor": "Efficient Optical Quantification of Heterogeneous Emitter Ensembles: Defect-based quantum emitters in solid state materials offer a promising\nplatform for quantum communication and sensing. Confocal fluorescence\nmicroscopy techniques have revealed quantum emitters in a multitude of host\nmaterials. In some materials, however, optical properties vary widely between\nemitters, even within the same sample. In these cases, traditional ensemble\nfluorescence measurements are confounded by heterogeneity, whereas individual\ndefect-by-defect studies are impractical. Here, we develop a method to\nquantitatively and systematically analyze the properties of heterogeneous\nemitter ensembles using large-area photoluminescence maps. We apply this method\nto study the effects of sample treatments on emitters in hexagonal boron\nnitride, and we find that low-energy (3 keV) electron irradiation creates\nemitters, whereas high-temperature (850 $^\\circ$C) annealing in an inert gas\nenvironment brightens emitters.",
        "positive": "Demagnetization factor dependence of energy of thick ferromagnetic films: Second order perturbed Heisenberg Hamiltonian was employed to study the\nvariation of energy of ferromagnetic thick films with demagnetization factor.\nUnder the influence of demagnetization factor given by =6.6, the sc(001) film\nwith 10000 layers can be easily oriented in 0.6 radians direction for the\nvalues of energy parameters used in this report. Easy direction of thick\nfcc(001) film with 10000 layers was determined at 0.66 radians, when the\ndemagnetization factor is given by =2.6. The energy of sc(001) thick film is\nlarger than that of fcc(001) thick film. But the energy curve of fcc(001) thick\nfilm is smoother than that of sc(001)."
    },
    {
        "anchor": "Noval Si-C Compounds with High Thermal Conductivity under TPa in\n  Planetary Interior: Silicon carbide has excellent physical properties, such as high stability,\nthermal conductivity, and mechanical strength. It has been widely used in\nhigh-power devices, catalysis, material processing, and other fields and is of\ngreat significance in basic discipline research. We used crystal structure\nsearch and first principles calculation to predict four new silicon carbide\nstructures stabilized within 3TPa. Pnma (SiC) replaces B1 (SiC) above 2.6TPa,\nand the new component Si3C2 becomes the most stable after 2.5TPa. P4/mbm phase\nSi3C2 under high pressure has electrode characteristics. The silicon-carbide\nstructure is metallic in the study pressure range, and the electrons contribute\nmost of the thermal conductivity, which is of great significance for the\nthermal evolution of silicon-carbide-like terrestrial planets. In addition, we\npropose a new silicon carbide planetary model and calculate the sound velocity\nof Si3C2 under TPa. Therefore, our research has deepened the understanding of\nsilicon-carbide terrestrial planets' internal structure and thermal evolution,\nexplored the complex silicon-carbide phase space, and enriched the\nsilicon-carbide phase diagram.",
        "positive": "Ultrathin epitaxial ferroelectric films grown on compressive substrates:\n  Competition between the surface and strain effects: The mean-field Landau-type theory is used to analyze the polarization\nproperties of epitaxial ferroelectric thin films grown on dissimilar cubic\nsubstrates, which induce biaxial compressive stress in the film plane. The\nintrinsic effect of the film surfaces on the spontaneous polarization is taken\ninto account via the concept of the extrapolation length. The theory\nsimultaneously allows for the influence of the misfit strain imposed on the\nfilm lattice by a thick substrate. Numerical calculations are performed for\nPbTiO3 and BaTiO3 films under an assumption of the polarization reduction in\nsurface layers. The film mean polarization is calculated as a function of film\nthickness, temperature, and misfit strain. It is shown that the negative\nintrinsic size effect is reduced in epitaxial films due to the in-plane\ncompression of the film lattice. At room temperature, strong reduction of the\nmean polarization may take place only in ultrathin films (thickness ~ 1 nm).\nTheoretical predictions are compared with the available experimental data on\npolarization properties of BaTiO3 films grown on SrRuO3 coated SrTiO3."
    },
    {
        "anchor": "Spatial Charge Inhomogeneity and Defect States in Topological Dirac\n  Semimetal Thin Films: The close approach of the Fermi energy EF of a Dirac semimetal to the Dirac\npoint ED uncovers new physics such as velocity renormalization,1,2,3 and the\nDirac plasma 4,5 at |EF -ED| < kBT, where kBT is the thermal energy. In\ngraphene, substrate disorder drives fluctuations in EF. Three-dimensional\ntopological Dirac semimetals (TDS)6,7 obviate the substrate, and should show\nreduced EF fluctuations due to better metallic screening and higher dielectric\nconstants. Here we map the potential fluctuations in TDS Na3Bi using a scanning\ntunneling microscope. The rms potential fluctuations are significantly smaller\nthan room temperature ({\\Delta}EF,rms = 4-6 meV = 40-70 K) and comparable to\nthe highest quality graphene on h-BN;8 far smaller than graphene on SiO2,9,10\nor the Dirac surface state of a topological insulator.11 Surface Na vacancies\nproduce a novel resonance close to the Dirac point with surprisingly large\nspatial extent and provides a unique way to tune the surface density of states\nin a TDS thin-film material.",
        "positive": "Variable-wavelength quick scanning nano-focused X-ray microscopy for in\n  situ strain and tilt mapping: Compression of micro-pillars is followed in situ by a quick nano-focused\nX-ray scanning microscopy technique combined with three-dimensional reciprocal\nspace mapping. Compared to other attempts using 2 X-ray nanobeams, it avoids\nany motion or vibration that would lead to a destruction of the sample. The\ntechnique consists of scanning both the energy of the incident nano-focused\nX-ray beam and the in-plane translations of the focusing optics along the X-ray\nbeam. Here, we demonstrate the approach by imaging the strain and lattice\norientation of Si micro-pillars and their pedestals during in situ compression.\nVarying the energy of the incident beam instead of rocking the sample and\nmapping the focusing optics instead of moving the sample supplies a\nvibration-free measurement of the reciprocal space maps without removal of the\nmechanical load. The maps of strain and lattice orientation are in good\nagreement with the ones recorded by ordinary rocking-curve scans.\nVariable-wavelength quick scanning X-ray microscopy opens the route for in situ\nstrain and tilt mapping towards more diverse and complex materials\nenvironments, especially where sample manipulation is difficult."
    },
    {
        "anchor": "Effect of lattice strain and defects on the superconductivity of MgB2: The influence of lattice strain and Mg vacancies on the superconducting\nproperties of MgB2 samples has been investigated. High quality samples with\nsharp superconducting transitions were synthesized. The variation in lattice\nstrain and Mg vacancy concentrations were obtained by varying the synthesis\nconditions. It was found that high strain (~1%) and the presence of Mg\nvacancies (~ 5 %) resulted in lowering the Tc by only 2 K.",
        "positive": "Luminescence of cadmium fluoride doped with rare-earth ions: Absorption, excitation and emission spectra of cadmium fluoride crystals\ndoped with rare-earth ions were investigated. In contrast to alkaline-earth\nfluorides the absorption spectra due to 4f - 5d transitions of Ce$^{3+}$,\nPr$^{3+}$ and Tb$^{3+}$ ions are broadened. No 5d-4f emissions were observed.\nThese prove that 5d(e$_g$) levels of rare earth ions lie in conduction band of\nCdF$_2$ crystal. Emission spectra of Tb$^{3+}$ show the group of 4f-4f\n$^5$D$_4$-$^7$F$_j$ lines in contrast to other alkaline-earth fluorides where\nemission due to $^5$D$_3$-$^7$F$_j$ transitions is also observed. The absence\nof the emission is due to position of $^5$D$_3$ level within condution band.\n  Among the all measured crystals doped with impurity ions (Pr, Nd, Eu, Ho, Tb,\nTm, Yb, Ga, In or Mn), the CdF$_2$ doped with Pr$^{3+}$, Tb$^{3+}$, or\nMn$^{2+}$ ions have the highest light outputs under x-ray excitation."
    },
    {
        "anchor": "PCrystalX -- Web Application: PCrystalX-Web is a web application developed to be easy and fast to use. The\npurpose of the software is that researchers from any area are able to use two\nmethods to analyze an X-ray diffraction pattern more straightforwardly. With\nthe full width at half maximum (FWHM) as a function of 2$\\theta$ for each peak,\nit is possible to estimate the crystallite size by the Scherrer equation and\napply the Williamson-Hall methods. PCrystalX-Web is a simplified version of the\nPCrystalX Software [1] program, which is still under development.",
        "positive": "Thermal Magnetoelectrics in all Inorganic Quasi-Two-Dimensional Halide\n  Perovskites: From lithium-ion batteries to high-temperature superconductors, oxide\nmaterials have been widely used in electronic devices. However, demands of\nfuture technologies require materials beyond oxides, as anion chemistries\ndistinct from oxygen can expand the palette of mechanisms and phenomena, to\nachieve superior functionalities. Examples include nitride-based wide bandgap\nsemiconductors and halide perovskite solar cells, with MAPbBr3 being a\nrepresentation revolutionizing photovoltaics research. Here, we demonstrate\nmagnetoelectric behaviour in quasi-two-dimensional halides (K,Rb)3Mn2Cl7\nthrough simultaneous thermal control of electric and magnetic polarizations by\nexploiting a polar-to-antipolar displacive transition. Additionally, our\ncalculations indicate a possible polarization switching path including a strong\nmagnetoelectric coupling, indicating halides can be excellent platforms to\ndesign future multiferroic and ferroelectric devices. We expect our findings to\nbroaden the exploration of multiferroics to non-oxide materials and open access\nto novel mechanisms, beyond conventional electric/magnetic control, for\ncoupling ferroic orders."
    },
    {
        "anchor": "Hexagonal High-Entropy Alloys: We report on the discovery of a high-entropy alloy with a hexagonal crystal\nstructure. Equiatomic samples in the alloy system Ho-Dy-Y-Gd-Tb were found to\nsolidify as homogeneous single-phase high-entropy alloys. The results of our\nelectron diffraction investigations and high-resolution scanning transmission\nelectron microscopy are consistent with a Mg-type hexagonal structure. The\npossibility of hexagonal high-entropy alloys in other alloy systems is\ndiscussed.",
        "positive": "Elastic Properties of Carbon nanotubes : An atomistic approach: Energetically the single sheet of graphite (graphene) is more stable than the\nnanotube. The energy difference between the two systems can be directly related\nto the strain energy involved in rolling up the graphene sheet to form the\nnanotube. We have carried out first principle electronic structure calculations\nand evaluated the strain energy as a function of the nanotube radius. The\ndependence of the strain energy on the diameter of the nanotube has been found\nby several groups to be welldescribed by a continuum elasticity model. We\nattempt to examine why this is the case and show where atomistics enter the\ndescription."
    },
    {
        "anchor": "Intrinsically Activated SrTiO3: Photocatalytic H2 Evolution from Neutral\n  Aqueous Methanol Solution in the Absence of Any Noble Metal Cocatalyst: Noble metal cocatalysts are conventionally a crucial factor in\noxide-semiconductor-based photocatalytic hydrogen generation. In the present\nwork, we show that optimized high-temperature hydrogenation of commercially\navailable strontium titanate (SrTiO3) powder can be used to engineer an\nintrinsic cocatalytic shell around nanoparticles that can create a\nphotocatalyst that is highly effective without the use of any additional\ncocatalyst for hydrogen generation from neutral aqueous methanol solutions.\nThis intrinsic activation effect can also be observed for SrTiO3[100] single\ncrystal as well as Nb-doped SrTiO3 (100) single crystal. For all types of\nSrTiO3 samples (nanopowders and either of the single crystals), hydrogenation\nunder optimum conditions leads to a surface-hydroxylated layer together with\nlattice defects visible by transmission electron microscopy, electron\nparamagnetic resonance (EPR), and photoluminescence (PL). Active samples\nprovide states in a defective matrix -- this is in contrast to the inactive\ndefects formed in other reductive atmospheres. In aqueous media, active SrTiO3\nsamples show a significant negative shift of the flatband potential (in\nphotoelectrochemical as well as in capacitance data) and a lower\ncharge-transfer resistance for photoexcited electrons. We therefore ascribe the\nremarkable cocatalyst-free activation of the material to a synergy between\nthermodynamics (altered interface energetics induced by hydroxylation) and\nkinetics (charge transfer mediation by suitable Ti3+ states).",
        "positive": "Charge-density-wave state induced by structural distortion in\n  heavy-fermion compounds Ce$_3$M$_4$Sn$_{13}$ (M=Co, Ru, Rh): In previous reports a structural transition from a cubic phase of\nYb$_3$Rh$_4$Sn$_{13}$ - type to the superlattice variant has been reported at\n$\\sim160$ K for a series of skutterudite-related Ce$_3$M$_4$Sn$_{13}$\ncompounds, where M=Co, Ru or Rh. We have simulated the low-temperature XRD\ndiffraction patterns of the distorted unit cell using written for that purpose\nDISTorX program. The method proposed here for x-ray diffraction analysis\nobtains the XRD patterns from the atomic positions and allows to investigate\ncrystal structure without imposed symmetry operations. We have indicated\ncrystallographic plane where distortion occurs and explained possible origin of\nCDW in these materials. We have also shown that distortion caused by the charge\ndensity wave leads to significantly changes of the intensity of diffraction\nlines."
    },
    {
        "anchor": "Photo-to-heat conversion of broadband metamaterial absorbers based on\n  TiN nanoparticles under laser and solar illumination: We theoretically investigate photothermal heating of ultra-flexible\nmetamaterials, which are obtained by randomly mixing TiN nanoparticles in\npolydimethylsiloxane (PDMS). Due to the plasmonic properties of TiN\nnanoparticles, incident light is perfectly absorbed in a broadband range\n(300-3000 nm) to generate heat within these metamaterials. Under irradiation of\nan 808 nm near-infrared laser with different intensities, our predicted\ntemperature rises as a function of time agree well with recent experimental\ndata. For a given laser intensity, the temperature rise varies\nnon-monotonically with concentration of TiN nanoparticles because the\nenhancement of thermal conductivity and absorbed energy as adding plasmonic\nnanostructures leads to opposite effects on the heating process. When the model\nis extended to solar heating, photothermal behaviors are qualitatively similar\nbut the temperature increase is less than 13 $K$. Our studies would provide\ngood guidance for future experimental studies on the photo-to-heat conversion\nof broadband perfect absorbers.",
        "positive": "Chiral magnetoresistance in the Weyl semimetal NbP: NbP is a recently realized Weyl semimetal (WSM), hosting Weyl points through\nwhich conduction and valence bands cross linearly in the bulk and exotic Fermi\narcs appear. However, the most intriguing transport phenomenon of a WSM, the\nchiral anomaly-induced negative magnetoresistance (NMR) in parallel electric\nand magnetic fields, has yet to be observed in NbP. In intrinsic NbP the Weyl\npoints lie far from the Fermi energy, making chiral magneto-transport elusive.\nHere, we use Ga-doping to relocate the Fermi energy in NbP sufficiently close\nto the Weyl points, for which the different Fermi surfaces are verified by\nresultant quantum oscillations. Consequently, we observe a NMR for parallel\nelectric and magnetic fields, which is considered as a signature of the chiral\nanomaly in condensed-matter physics. The NMR survives up to room temperature,\nmaking NbP a versatile material platform for the development of Weyltronic\napplications."
    },
    {
        "anchor": "Coexistence of Co3+ and Co2+ in ceramic Co3TeO6; XANES, Magnetization\n  and first principle study: Evidence of coexistence of Co3+ with Co2+ in ceramic Co3TeO6 through XANES,\nDC magnetization and first principal studies is provided. XANES along with\nlinear combination fit provide relative concentrations of Co2+ and\nCo3+.Temperature dependent DC magnetization exhibits the same antiferromagnetic\nbehavior as observed in single crystal. The presence of both Co2+ and Co3+\nsuggests that if the later is in high spin state, the effective magnetic moment\nis similar to that observed in single crystal studies. In contrast, if Co3+ is\nin low spin state effective magnetic moment is similar to that observed in\nCo3O4. It is further shown that both Co2+ and Co3+ in high spin states\nconstitute a favorable ground state through first principle calculations where\nRietveld refined Synchrotron X-ray diffraction data are inputs.",
        "positive": "Stochastic ferrimagnetic Landau-Lifshitz-Bloch equation for finite\n  magnetic structures: Precise modeling of the magnetization dynamics of nanoparticles with finite\nsize effects at fast varying temperatures is a computationally challenging\ntask. Based on the Landau-Lifshitz-Bloch (LLB) equation we derive a coarse\ngrained model for disordered ferrimagnets, which is both fast and accurate.\nFirst, we incorporate stochastic fluctuations to the existing ferrimagnetic LLB\nequation. Further, we derive a thermodynamic expression for the temperature\ndependent susceptibilities, which is essential to model finite size effects.\nTogether with the zero field equilibrium magnetization the susceptibilities are\nused in the stochastic ferrimagnetic LLB to simulate a $5\\times10$ nm$^2$\nferrimagnetic GdFeCo particle with 70 % FeCo and 30 % Gd under various external\napplied fields and heat pulses. The obtained trajectories agree well with those\nof an atomistic model, which solves the stochastic Landau-Lifshitz-Gilbert\nequation for each atom. Additionally, we derive an expression for the\nintergrain exchange field which couple the ferromagnetic sublattices of a\nferrimagnet. A comparison of the magnetization dynamics obtained from this\nsimpler model with those of the ferrimagnetic LLB equation shows a perfect\nagreement."
    },
    {
        "anchor": "Comment on \"High-pressure phases of group-II difluorides: Polymorphism\n  and superionicity\": Nelson et al. [Phys. Rev. B 95, 054118 (2017)] recently have reported\nfirst-principles calculations on the behaviour of group-II difluorides\n(BeF$_{2}$, MgF$_{2}$, and CaF$_{2}$) under high-pressure and low- and\nhigh-temperature conditions. The calculations were based on ab initio random\nstructure searching and the quasi-harmonic approximation (QHA). Here, we point\nout that, despite the of inestimable value of such calculations at\nhigh-pressure and low-temperature conditions, the high-$P$ high-$T$ phase\ndiagram proposed by Nelson et al. for CaF$_{2}$ neither is in qualitative\nagreement with the results of previous ab initio molecular dynamics simulations\nnor with the existing corps of experimental data. Therefore, we conclude that\nthe QHA-based approach employed by Nelson et al. cannot be applied reliably to\nthe study of phase boundaries involving superionic phases. This conclusion is\nfurther corroborated by additional ab initio calculations performed in the\nsuperionic compounds SrF$_{2}$, BaF$_{2}$, Li$_{3}$OCl, and AgI.",
        "positive": "Multi-phonon diffuse scattering in solids from first-principles:\n  Application to layered crystals and 2D materials: Time-resolved diffuse scattering experiments have gained increasing attention\ndue to their potential to reveal non-equilibrium dynamics of crystal lattice\nvibrations with full momentum resolution. Although progress has been made in\ninterpreting experimental data on the basis of one-phonon scattering,\nunderstanding the role of individual phonons can be sometimes hindered by\nmulti-phonon excitations. In Ref. [{\\it arXiv:2103.10108}] we have introduced a\nrigorous approach for the calculation of the all-phonon inelastic scattering\nintensity of solids from first-principles. In the present work, we describe our\nimplementation in detail and show that multi-phonon interactions are captured\nefficiently by exploiting translational and time-reversal symmetries of the\ncrystal. We demonstrate its predictive power by calculating the scattering\npatterns of monolayer molybdenum disulfide (MoS$_2$), bulk MoS$_2$, and black\nphosphorus (bP), and we obtain excellent agreement with our measurements of\nthermal electron diffuse scattering. Remarkably, our results show that\nmulti-phonon excitations dominate in bP across multiple Brillouin zones, while\nin MoS$_2$ they play a less pronounced role. We expand our analysis for each\nsystem and examine the effect of individual atomic and interatomic vibrational\nmotion on the diffuse scattering signals. We further demonstrate the\nhigh-throughput capability of our approach by reporting all-phonon scattering\nmaps of 2D MoSe2, WSe2, WS2, graphene, and CdI2, rationalizing in each case the\neffect of multi-phonon processes. As a side point, we show that the special\ndisplacement method reproduces the thermally distorted configuration that\ngenerates precisely the all-phonon diffuse pattern."
    },
    {
        "anchor": "Novel electronic and magnetic properties of BN sheet decorated with\n  hydrogen and fluorine: First principles calculations based on density functional theory reveal some\nunusual properties of BN sheet functionalized with hydrogen and fluorine. These\nproperties differ from those of similarly functionalized graphene even though\nboth share the same honeycomb structure. (1) Unlike graphene which undergoes a\nmetal to insulator transition when fully hydrogenated, the band gap of the BN\nsheet significantly narrows when fully saturated with hydrogen. Furthermore,\nthe band gap of the BN sheet can be tuned from 4.7 eV to 0.6 eV and the system\ncan be a direct or an indirect semiconductor or even a half-metal depending\nupon surface coverage. (2) Unlike graphene, BN sheet has hetero-atomic\ncomposition, when co-decorated with H and F, it can lead to anisotropic\nstructures with rich electronic and magnetic properties. (3) Unlike graphene,\nBN sheets can be made ferromagnetic, antiferromagnetic, or magnetically\ndegenerate depending upon how the surface is functionalized. (4) The stability\nof magnetic coupling of functionalized BN sheet can be further modulated by\napplying external strain. Our study highlights the potential of functionalized\nBN sheets for novel applications.",
        "positive": "The New Nitrides: Layered, Ferroelectric, Magnetic, Metallic and\n  Superconducting Nitrides to Boost the GaN Photonics and Electronics\n  Eco-System: The nitride semiconductor materials GaN, AlN, and InN, and their alloys and\nheterostructures have been investigated extensively in the last 3 decades,\nleading to several technologically successful photonic and electronic devices.\nJust over the past few years, a number of new nitride materials have emerged\nwith exciting photonic, electronic, and magnetic properties. Some examples are\n2D and layered hBN and the III-V diamond analog cBN, the transition metal\nnitrides ScN, YN, and their alloys (e.g. ferroelectric ScAlN), piezomagnetic\nGaMnN, ferrimagnetic Mn4N, and epitaxial superconductor/semiconductor NbN/GaN\nheterojunctions. This article reviews the fascinating and emerging physics and\nscience of these new nitride materials. It also discusses their potential\napplications in future generations of devices that take advantage of the\nphotonic and electronic devices eco-system based on transistors, light-emitting\ndiodes, and lasers that have already been created by the nitride\nsemiconductors."
    },
    {
        "anchor": "Oxygen atoms and molecules at Lanthanum-Strontium Manganite surfaces: A localized description, rather than energy bands, is appropriate for the\nmanganite substrate. Empty substrate levels lower in energy than occupied\noxygen levels indicate need for further terms beyond the Local Density\nApproximation. So also does van-der-Waals interaction between the two. Methods\nto include both are suggested by related, exactly soluble, two-electron\nproblems. The descriptions of the electronic structure of the molecule and a\nLaSrMnO3 (LSM) substrate are greatly simplified to allow incorporation of these\neffects and to treat a range of problems involving the interactions between\noxygen atoms, or oxygen molecules, and such a substrate. These include elastic\nimpacts, impacts with electronic transitions, and impacts with phonon\nexcitation. They provide for capture of the atoms or molecules by the surface,\nleaving the neutral molecule strongly bound over a Mn(4+) site. It is found\nthat oxygen vacancies in LSM diffuse as a neutral species, and can appear at\nthe surface. Bound molecules tend to avoid sites next to vacancies but, if\nthere, should drop one atom into the vacancy leaving the remaining triplet\noxygen atom bound to the resulting ideal surface, with no need for spin flips\nnor successive ionization steps.",
        "positive": "Magnetic domain-wall motion study under an electric field in a Finemet\n  thin film on flexible substrate: Influence of applied in-plane elastic strains on the static magnetic\nconfiguration of a 530 nm magnetostrictive FeCuNbSiB thin film. The in-plane\nstrains are induced via the application of a voltage to a piezoelectric\nactuator on which the film/substrate system was glued. A quantitative\ncharacterization of the voltage dependence of the induced-strain at the surface\nof the film was performed using a digital image correlation technique. MFM\nimages at remanence (H=0 Oe and U=0 V) clearly reveal the presence of weak\nstripe domains. The effect of the voltage-induced strain shows the existence of\na threshold value above, which the break of the stripe configuration set in.\nFor a maximum strain of exx~0.5*10-3 we succeed in destabilizing the stripes\nconfiguration helping the setting up of a complete homogeneous magnetic\npattern."
    },
    {
        "anchor": "Electrically tunable quantum anomalous Hall effect in 5d\n  transition-metal adatoms on graphene: The combination of the unique properties of graphene with spin polarization\nand magnetism for the design of new spintronic concepts and devices has been\nhampered by the small Coulomb interaction and the tiny spin-orbit coupling of\ncarbon in pristine graphene. Such device concepts would take advantage of the\ncontrol of the spin degree of freedom utilizing the widely available electric\nfields in electronics or of topological transport mechanisms such as the\nconjectured quantum anomalous Hall effect. Here we show, using first-principles\nmethods, that 5d transition-metal (TM) adatoms deposited on graphene display\nremarkable magnetic properties. All considered TM adatoms possess significant\nspin moments with colossal magnetocrystalline anisotropy energies as large as\n50 meV per TM atom. We reveal that the magneto-electric response of deposited\nTM atoms is extremely strong and in some cases offers even the possibility to\nswitch the spontaneous magnetization direction by a moderate external electric\nfield. We predict that an electrically tunable quantum anomalous Hall effect\ncan be observed in this type of hybrid materials.",
        "positive": "Role of Interlayer Coupling on the Evolution of Band Edges in Few-Layer\n  Phosphorene: Using first-principles calculations, we have investigated the evolution of\nband-edges in few-layer phosphorene as a function of the number of P layers.\nOur results predict that monolayer phosphorene is an indirect band gap\nsemiconductor and its valence band edge is extremely sensitive to strain. Its\nband gap could undergo an indirect-to-direct transition under a lattice\nexpansion as small as 1% along zigzag direction. A semi-empirical interlayer\ncoupling model is proposed, which can well reproduce the evolution of valence\nband-edges obtained by first-principles calculations. We conclude that the\ninterlayer coupling plays a dominated role in the evolution of the band-edges\nvia decreasing both band gap and carrier effective masses with the increase of\nphosphorene thickness. A scrutiny of the orbital-decomposed band structure\nprovides a better understanding of the upward shift of valence band maximum\nsurpassing that of conduction band minimum."
    },
    {
        "anchor": "Magnetocaloric effect in Ni2(Mn,Cu)Ga0.84Al0.16 Heusler alloys: Polycrystalline Heusler compounds Ni2Mn0.75Cu0.25Ga0.84Al0.16 with a\nmartensitic transition between ferromagnetic phases and\nNi2Mn0.70Cu0.30Ga0.84Al0.16 with a magnetostructural transformation were\ninvestigated by magnetization and thermal measurements, both as a function of\ntemperature and magnetic field. The compound Ni2Mn0.75Cu0.25Ga0.84Al0.16\npresents a large magnetocaloric effect among magnetically aligned structures\nand its causes are explored. In addition, Ni2Mn0.70Cu0.30Ga0.84Al0.16 shows\nvery high, although irreversible, entropy and adiabatic temperature change at\nroom temperature under a magnetic field change 0-1 T. Improved refrigerant\ncapacity is also a highlight of the 30% Cu material when compared to similar\nNi2MnGa-based alloys.",
        "positive": "Adaptive mesh computation of polycrystalline pattern formation using a\n  renormalization-group reduction of the phase-field crystal model: We implement an adaptive mesh algorithm for calculating the space and time\ndependence of the atomic density field during materials processing. Our\nnumerical approach uses the systematic renormalization-group formulation of the\nphase field crystal model to provide the underlying equations for the complex\namplitude of the atomic density field--a quantity that is spatially uniform\nexcept near topological defects, grain boundaries and other lattice\nimperfections. Our algorithm is a hybrid formulation of the amplitude\nequations, combining Cartesian and polar decompositions of the complex\namplitude. We show that this approach leads to an acceleration by three orders\nof magnitude in model calculations of polycrystalline domain formation in two\ndimensions."
    },
    {
        "anchor": "Equation of state of atomic solid hydrogen by stochastic many-body wave\n  function methods: We report a numerical study of the equation of state of crystalline\nbody-centered-cubic (BCC) hydrogen, tackled with a variety of complementary\nmany-body wave function methods. These include continuum stochastic techniques\nof fixed-node diffusion and variational quantum Monte Carlo, and the Hilbert\nspace stochastic method of full configuration-interaction quantum Monte Carlo.\nIn addition, periodic coupled-cluster methods were also employed. Each of these\nmethods is underpinned with different strengths and approximations, but their\ncombination in order to perform reliable extrapolation to complete basis set\nand supercell size limits gives confidence in the final results. The methods\nwere found to be in good agreement for equilibrium cell volumes for the system\nin the BCC phase, with a lattice parameter of 3.307 Bohr.",
        "positive": "Emergence of Chaos in Magnetic-Field-Driven Skyrmions: We explore magnetic-field-driven chaos in magnetic skyrmions. Oscillating\nmagnetic fields induce nonlinear dynamics in skyrmions, arising from the\ncoupling of the secondary gyrotropic mode with a non-uniform, breathing-like\nmode. Through micromagnetic simulations, we observe complex patterns of\nhypotrochoidal motion in the orbital trajectories of the skyrmions, which are\ninterpreted using bifurcation diagrams and local Lyapunov exponents. Our\nfindings demonstrate that different nonlinear behaviors of skyrmions emerge at\ndistinct temporal stages, depending on the nonlinear dynamic parameters.\nInvestigating the abundant dynamic patterns of skyrmions during the emergence\nof chaos not only enhances device reliability but also provides useful\nguidelines for establishing chaos computing based on skyrmion dynamics."
    },
    {
        "anchor": "Optical Spectroscopy of the Hole Spin in GaMnAs Acceptors: The spin state of holes bound to Mn acceptors in GaMnAs is investigated by\noptical spectroscopy. Concentrations of Mn from 10^17 to 10^19 cm^-3 were\nstudied as a function of magnetic field and temperature. The photoluminescence\nfrom recombination of electrons with holes bound in the Mn-acceptor complex\n(MAC) displays multiple spectral peaks. The circular polarization rho of these\npeaks increases with increasing magnetic field and saturates at rho ~= 1/3.\nThis value of polarization is expected from modeling the addition of spin\nangular momentum and interband optical transition matrix elements.",
        "positive": "Solute drag forces from equilibrium interface fluctuations: The design of polycrystalline alloys hinges on a predictive understanding of\nthe interaction between the diffusing solutes and the motion of the constituent\ncrystalline interfaces. Existing frameworks ignore the dynamic multiplicity of\nand transitions between the interfacial structures and phases. Here, we develop\na computationally-accessible theoretical framework based on short-time\nequilibrium fluctuations to extract the drag force exerted by the segregating\nsolute cloud. Using three distinct classes of computational techniques, we show\nthat the random walk of a solute-loaded interface is necessarily non-classical\nat short time-scales as it occurs within a confining solute cloud. The much\nslower stochastic evolution of the cloud allows us to approximate the\nshort-time behavior as an exponentially sub-diffusive Brownian motion in an\nexternal trapping potential with a stiffness set by the average drag force. At\nlonger time-scales, the interfacial and bulk forces lead to a gradual recovery\nof classical random walk of the interface with a diffusivity set by the\nextrinsic mobility. The short-time response is accessible via {\\it ab-initio}\ncomputations, offering a firm foundation for high throughput, rational design\nof alloys for controlling microstructural evolution in polycrystals, and in\nparticular for nanocrystalline alloys-by-design."
    },
    {
        "anchor": "On the wiedemann-franz law in thermoelectric composites: Theoretical analysis of the effect of thermoelectric phenomena on the\nrelation of effective electrical and thermal conductivity in the\nmacroscopically inhomogeneous media is carried out. Plane-layered structures,\ntwo-dimensional self-dual and three-dimensional randomly inhomogeneous media\nare examined. It is shown that the relation of effective electrical to thermal\nconductivity, which is independent of concentration in so-called\nWiedemann-Franz media, in the case of high values of internal thermoelectric\nfigure of merit can be considerably different from the one for the local values\nin each phase. The decrease of the relation may have negative impact on the\neffective figure of merit of composites and thus lead to the decrease of\nthermoelectric devices efficiency.",
        "positive": "Grain-Boundary Topological Phase Transitions: The formation and migration of disconnections (line defects constrained to\nthe grain boundary (GB) plane with both dislocation and step character) control\nmany of the kinetic and dynamical properties of GBs and the polycrystalline\nmaterials of which they are central constituents. We demonstrate that GBs\nundergo a finite-temperature topological phase transition of the\nKosterlitz-Thouless (KT) type. This phase transition corresponds to the\nscreening of long-range interactions between (and unbinding of) disconnections.\nThis phase transition leads to abrupt change in the behavior of GB migration,\nGB sliding, and roughening. We analyze this KT transition through mean-field\ntheory, renormalization group theory, and kinetic Monte Carlo simulations, and\nexamine how this transition affects microstructure-scale phenomena such as\ngrain growth stagnation, abnormal grain growth and superplasticity."
    },
    {
        "anchor": "Low temperature transport properties of pyrolytic graphite sheet: We have made thermal and electrical transport measurements of uncompressed\npyrolytic graphite sheet (uPGS), a mass-produced thin graphite sheet with\nvarious thicknesses between 10 and 100 {\\mu}m, at temperatures between 2 and\n300 K. Compared to exfoliated graphite sheets like Grafoil, uPGS has much\nhigher conductivities by an order of magnitude because of its high\ncrystallinity confirmed by X-ray diffraction and Raman spectroscopy. This\nmaterial is advantageous as a thermal link of light weight in a wide\ntemperature range particularly above 60 K where the thermal conductivity is\nmuch higher than common thermal conductors such as copper and aluminum alloys.\nWe also found a general relationship between thermal and electrical\nconductivities in graphite-based materials which have highly anisotropic\nconductivities. This would be useful to estimate thermal conductance of a\ncryogenic part made of these materials from its electrical conductance more\neasily measurable at low temperature.",
        "positive": "Weak electron-phonon coupling in the early alkali atomic wires: The structural, electronic and vibrational properties of atomic wires\ncomposed of the early alkali metals lithium and sodium are studied using\ndensity functional perturbation theory. The s-like electronic states near the\nFermi level couple very weakly to longitudinal acoustic phonons and not at all\nto the transverse acoustic phonons, which results in a weak overall\nelectron-phonon coupling. The results are compared to earlier studies on the\nelectron-phonon coupling in metallic atomic wires and reinforces the idea that\ns-like states at the Fermi level give rise to weak electron-phonon coupling in\none-dimension, in contrast with materials containing d-like states at the Fermi\nlevel which have correspondingly larger electron-phonon coupling due to\ninteractions with transverse phonons."
    },
    {
        "anchor": "Three-dimensional reconstruction of the Fermi surface of LaB6: The 2-dimensional angular correlations of the positron annihilation radiation\n(2D-ACAR) on a single crystal of LaB6 was measured for three projections. The\n2D-ACAR spectra were subjected to the Van Citter-Gerhard deconvolution\nalghorithm. From the experimental spectra we produced the 3D k-space density\nrho(k) via three different methods: i) we reconstructed the 3D\nelectron-positron momentum density rho(p) via the Cormack method. rho(k) was\nthen obtained by applying the 3D LCW transformation to rho(p). ii) The same\nsteps of point i) were repeated adopting a modified Fourier-transform-based\nalgorithm. iii) The 3d k-space occupancy rho(k) was obtained directly by\nparameterising the Fermi surface volume with prolate ellipsoids whose axes were\ndetermined by a least-square fit to the 2D LCW transformations applied to two\nhigh symmetry projections. The ellipsoids diameters along high symmetry\ndirections of the cubic Brillouin zone (BZ), as a fraction of the BZ size, were\n0.64 (dir. X-M) and 0.82 (dir. Gamma-X). The resulting Fermi volume, as a\nfraction of the BZ volume, was 0.55. These results agree within 1% with those\nobtained via the de Haas van Alphen experiments.",
        "positive": "Determination of band alignment in the single layer MoS2/WSe2\n  heterojunction: The emergence of transition metal dichalcogenides (TMDs) as 2D electronic\nmaterials has stimulated proposals of novel electronic and photonic devices\nbased on TMD heterostructures. Here we report the determination of band offsets\nin TMD heterostructures by using microbeam X-ray photoelectron spectroscopy\n({\\mu}-XPS) and scanning tunneling microscopy/spectroscopy (STM/S). We\ndetermine a type-II alignment between $\\textrm{MoS}_2$ and $\\textrm{WSe}_2$\nwith a valence band offset (VBO) value of 0.83 eV and a conduction band offset\n(CBO) of 0.76 eV. First-principles calculations show that in this\nheterostructure with dissimilar chalcogen atoms, the electronic structures of\n$\\textrm{WSe}_2$ and $\\textrm{MoS}_2$ are well retained in their respective\nlayers due to a weak interlayer coupling. Moreover, a VBO of 0.94 eV is\nobtained from density functional theory (DFT), consistent with the experimental\ndetermination."
    },
    {
        "anchor": "Edge States: Topological Insulators, Superconductors and QCD Chiral Bags: The dynamics of the magnetic field in a superconducting phase is described by\nan effective massive bosonic field theory. If the superconductor is confined in\na domain M with boundary \\partial M, the boundary conditions of the\nelectromagnetic fields are predetermined by physics. They are time-reversal and\nalso parity invariant for adapted geometry. They lead to edge excitations while\nin comparison, the bulk energies have a large gap. A similar phenomenon occurs\nfor topological insulators where appropriate boundary conditions for the Dirac\nHamiltonian also lead to similar edge states and an 'incompressible bulk'. They\ngive spin-momentum locking as well. In addition time-reversal and parity\ninvariance emerge for adapted geometry. Similar edge states appear in QCD bag\nmodels with chiral boundary conditions.",
        "positive": "Shape transition in ZnO nanostructures and its effect on blue-green\n  photoluminescence: We report that ZnO nanostructures synthesized by chemical route undergo a\nshape transition at ~ 20 nm from spherical to hexagonal morphology thereby\nchanging the spectral components of the blue-green emission. Spherically shaped\nnanocrystals (size range 11 -18 nm) show emission in the range of 555-564 nm\nand the emission shifts to the longer wavelength as the size increases. On the\nother hand, rods and hexagonal platelets (size range 20-85 nm), which is the\nequilibrium morphology after the shape transition, show emission near 465-500\nnm and it shifts to shorter wavelength as the size increases. The shape\ntransition also leads to relaxation of microstrain in the system. Our analysis\nshows that the visible emission originates from a defect layer on the\nnanostructure surface which is affected by the shape transition. The change in\nthe spectral component of the blue green emission on change of shape has been\nexplained as arising from band bending due to depletion layer in smaller\nspherical particles which is absent in the larger particles with flat faces."
    },
    {
        "anchor": "Atomic structures and electronic correlation of monolayer 1T-TaSe2: We investigate atomic and electronic structures of monolayer 1T-TaSe2 using\ndensity functional theory calculations. Monolayers of 1T-TaSe2 were recently\ngrown on graphene substrates and suggested as an intriguing Mott insulator\n[Nat. Phys. 16, 218 (2020)]. However, the prevailing structural model for the\nmodel system of 1T-TaS2, the cation-centered cluster of a David-star shape with\nstrong electron correlation, could not explain the characteristic and unusual\norbital splitting observed in scanning tunneling spectroscopy experiments. We\nsuggest an alternative structure model, an anion-centered cluster structure,\nwhich can reproduce most of the unusual spectroscopic characteristics with\nelectron doping from the substrate without electron correlation. The unusual\nspectroscopic features observed, thus, seems to indicate a simple and usual\nband insulating state. This work indicates the importance of a large structural\ndegree of freedom given for a cluster Mott insulator.",
        "positive": "Terahertz and infrared spectroscopic evidence of phonon-paramagnon\n  coupling in hexagonal piezomagnetic YMnO3: Terahertz and far-infrared electric and magnetic responses of hexagonal\npiezomagnetic YMnO3 single crystals are investigated. Antiferromagnetic\nresonance is observed in the spectra of magnetic permeability mu_a [H(omega)\noriented within the hexagonal plane] below the Neel temperature T_N. This\nexcitation softens from 41 to 32 cm-1 on heating and finally disappears above\nT_N. An additional weak and heavily-damped excitation is seen in the spectra of\ncomplex dielectric permittivity epsilon_c within the same frequency range. This\nexcitation contributes to the dielectric spectra in both antiferromagnetic and\nparamagnetic phases. Its oscillator strength significantly increases on heating\ntowards room temperature thus providing evidence of piezomagnetic or\nhigher-order couplings to polar phonons. Other heavily-damped dielectric\nexcitations are detected near 100 cm-1 in the paramagnetic phase in both\nepsilon_c and epsilon_a spectra and they exhibit similar temperature behavior.\nThese excitations appearing in the frequency range of magnon branches well\nbelow polar phonons could remind electromagnons; however, their temperature\ndependence is quite different. We have used density functional theory for\ncalculating phonon dispersion branches in the whole Brillouin zone. A detailed\nanalysis of these results and of previously published magnon dispersion\nbranches brought us to the conclusion that the observed absorption bands stem\nfrom phonon-phonon and phonon- paramagnon differential absorption processes.\nThe latter is enabled by a strong short-range in-plane spin correlations in the\nparamagnetic phase."
    },
    {
        "anchor": "The driving force behind the distortion of one-dimensional monatomic\n  chains - Peierls theorem revisited: The onset of distortion in one-dimensional monatomic chains with partially\nfilled valence bands is considered to be well-established by the Peierls\ntheorem, which associates the distortion with the formation of a band gap and a\nsubsequent gain in energy. Employing modern total energy methods on the test\ncases of lithium, sodium and carbon chains, we reveal that the distortion is\nnot universal, but conditional upon the balance between distorting and\nstabilizing forces. Furthermore, in all systems studied, the electrostatic\ninteractions between the electrons and ions act as the main driving force for\ndistortion, rather than the electron band lowering at the Fermi level as is\ncommonly believed. The main stabilizing force which drives the chains toward\ntheir symmetric arrangement is derived from the electronic kinetic energy. Both\nforces are affected by the external conditions, e.g. stress, and consequently\nthe instability of one-dimensional nanowires is conditional upon them. This\nbrings a new perspective to the field of one-dimensional metals, and may shed\nnew light on the distortion of more complex structures.",
        "positive": "Failure mechanism of monolayer graphene under hypervelocity impact of\n  spherical projectile: The excellent mechanical properties of graphene have enabled it as appealing\ncandidate in the field of impact protection or protective shield. By\nconsidering a monolayer graphene membrane, in this work, we assessed its\ndeformation mechanisms under hypervelocity impact (from 2 to 6 km/s), based on\na serial of in silico studies. It is found that the cracks are formed\npreferentially in the zigzag directions which are consistent with that observed\nfrom tensile deformation. Specifically, the boundary condition is found to\nexert an obvious influence on the stress distribution and transmission during\nthe impact process, which eventually influences the penetration energy and\ncrack growth. For similar sample size, the circular shape graphene possesses\nthe best impact resistance, followed by hexagonal graphene membrane. Moreover,\nit is found the failure shape of graphene membrane has a strong relationship\nwith the initial kinetic energy of the projectile. The higher kinetic energy,\nthe more number the cracks. This study provides a fundamental understanding of\nthe deformation mechanisms of monolayer graphene under impact, which is crucial\nin order to facilitate their emerging future applications for impact\nprotection, such as protective shield from orbital debris for spacecraft."
    },
    {
        "anchor": "Redox functionality mediated by adsorbed oxygen on a Pd-oxide film over\n  a Pd(100) thin structure: A first-principles study: Stable oxygen sites on a PdO film over a Pd(100) thin structures with a\n(sqrt{5} times sqrt{5}) R27^circ surface-unit cell are determined using the\nfirst-principles electronic structure calculations with the generalized\ngradient approximation. The adsorbed monatomic oxygen goes to a site bridging\ntwo 2-fold-coordinated Pd atoms or to a site bridging a 2-fold-coordinated Pd\natom and a 4-fold-coordinated Pd atom. Estimated reaction energies of CO\noxidation by reduction of the oxidized PdO film and N_2O reduction mediated by\noxidation of the PdO film are exothermic. Motion of the adsorbed oxygen atom\nbetween the two stable sites is evaluated using the nudged elastic band method,\nwhere an energy barrier for a translational motion of the adsorbed oxygen may\nbecome sim 0.45 eV, which is low enough to allow fluxionality of the surface\noxygen at high temperatures. The oxygen fluxionality is allowed by existence of\n2-fold-coordinated Pd atoms on the PdO film, whose local structure has\nsimilarity to that of Pd catalysts for the Suzuki-Miyaura cross coupling.\nAlthough NO_x (including NO_2 and NO) reduction is not always catalyzed only by\nthe PdO film, we conclude that there may happen continual redox reactions\nmediated by oxygen-adsorbed PdO films over a Pd surface structure, when the\ninflux of NO_x and CO continues, and when the reaction cycle is kept on a\nwell-designed oxygen surface.",
        "positive": "Unfolding femtoscale ionic movement in CuO through polarized Raman\n  spectroscopy: Recently, CuO has been proposed as a potential multiferroic material with\nhigh transition temperature. Competing models based on spin current and ionic\ndisplacements are invoked to explain ferroelectricity in CuO. The theoretical\nmodel predicting ionic displacement suggested that the shift in ions is\nessentially along b-axis with very small amplitude (~10-5 {\\AA}).\nExperimentally detecting displacements of such a small amplitude in a\nparticular direction is extremely challenging. Through our detailed polarized\nRaman spectroscopy study on epitaxial film of CuO, we have validated the\ntheoretical study and provided direct evidence of displacement along the\nb-axis. Our study provides important contribution in the high temperature\nmultiferroic compounds and showed for the first time, the use of the polarized\nRaman scattering in detecting ionic displacements at the femto-scale."
    },
    {
        "anchor": "Symmetry-Enforced Weyl Phonons: In spinful electronic systems, time-reversal symmetry makes that all Kramers\npairs at the time-reversal-invariant momenta are Weyl points (WPs) in chiral\ncrystals. Here, we find that such symmetry-enforced WPs can also emerge in\nbosonic systems ($e.g.$ phonons and photons) due to nonsymmorphic symmetries.\nWe demonstrate that for some nonsymmorphic chiral space groups, several\nhigh-symmetry $k$-points can host $only$ WPs in the phononic systems, dubbed\nsymmetry-enforced Weyl phonons (SEWPs). The SEWPs, enumerated in Table I, are\npinned at the boundary of the three-dimensional (3D) Brillouin zone (BZ) and\nprotected by nonsymmorphic crystal symmetries. By performing first-principles\ncalculations and symmetry analysis, we propose that as an example of SEWPs, the\ntwo-fold degeneracies at P are monopole WPs in K$_2$Sn$_2$O$_3$ with space\ngroup 199. The two WPs of the same chirality at two nonequivalent P points are\nrelated by time-reversal symmetry. In particular, at $\\sim 17.5$ THz, a spin-1\nWeyl phonon is also found at H, since two Weyl phonons at P carrying a non-zero\nnet Chern number cannot exist alone in the 3D BZ. The significant separation\nbetween P and H points makes the surface arcs long and clearly visible. Our\nfindings not only present an effective way to search for WPs in bosonic\nsystems, but also offer some promising candidates for studying monopole Weyl\nand spin-1 Weyl phonons in realistic materials.",
        "positive": "Magnetic interaction between GaMnAs layers via spin-polarized\n  quasi-two-dimensional hole gas: Monte Carlo simulation: The magnetic order resulting from an indirect exchange between magnetic\nmoments in the metallic phase of a Ga(1-x)Mn(x)As bilayered structure is\nstudied \"via\" Monte Carlo simulation. The coupling mechanism involves a\nperturbative calculation in second order of the interaction between the\nmagnetic moments and carriers (holes). We take into account a possible\npolarization of the hole gas establishing, thus, self-consistency between the\nmagnetic order and the electronic structure. It leads to a ferromagnetic order\neven in the case of thin layers. This fact is analyzed in terms of the inter-\nand intra-layer interactions."
    },
    {
        "anchor": "Growth mode control of the free carrier density in SrTiO3-d films: We have studied the growth dynamics and electronic properties of SrTiO3-d\nhomoepitaxial films by pulsed laser deposition. We find the two dominant\nfactors determining the growth mode are the kinetics of surface crystallization\nand oxidation. When matched, persistent two-dimensional layer-by-layer growth\ncan be obtained for hundreds of unit cells. By tuning these kinetic factors,\noxygen vacancies can be frozen in the film, allowing controlled, systematic\ndoping across a metal-insulator transition. Metallic films can be grown,\nexhibiting Hall mobilities as high as 25,000 cm2/Vs.",
        "positive": "First-principles study of the bandgap renormalization and optical\n  property of $\u03b2$-LiGaO$_2$: ${\\beta}$-LiGaO$_2$ with an orthorhombic wurtzite-derived structure is a\ncandidate ultrawide direct-bandgap semiconductor. In this work, using the\nnon-adiabatic Allen-Heine-Cardona approach, we investigate the bandgap\nrenormalization arising from electron-phonon coupling. We find a sizable\nzero-point motion correction of -0.362 eV to the gap at ${\\Gamma}$, which is\ndominated by the contributions of long-wavelength longitudinal optical phonons.\nThe bandgap of ${\\beta}$-LiGaO$_2$ decreases monotonically with increasing\ntemperature. We investigate the optical spectra by comparing the model\nBethe-Salpether equation method with the independent-particle approximation.\nThe calculated optical spectra including electron-hole interactions exhibit\nstrong excitonic effects, in qualitative agreement with experiment. The\ncontributing interband transitions and the binding energy for the excitonic\nstates are analyzed."
    },
    {
        "anchor": "Growth mode, magnetic and magneto-optical properties of\n  pulsed-laser-deposited Au/Co/Au(111) trilayers: The growth mode, magnetic and magneto-optical properties of epitaxial\nAu/Co/Au(111) ultrathin trilayers grown by pulsed-laser deposition (PLD) under\nultra-high vacuum are presented. Sapphire wafers buffered with a\nsingle-crystalline Mo(110) bilayer were used as substrates. Owing to\nPLD-induced interfacial intermixing at the lower Co/Au(111) interface, a\nlayer-by-layer growth mode is promoted. Surprisingly, despite this intermixing,\nferromagnetic behavior is found at room temperature for coverings starting at 1\natomic layer (AL). The films display perpendicular magnetization with\nanisotropy constants reduced by 50% compared to TD-grown or electrodeposited\nfilms, and with a coercivity more than one order of magnitude lower ($\\lesssim$\n5 mT). The magneto-optical (MO) response in the low Co thickness range is\ndominated by Au/Co interface contributions. For thicknesses starting at 3 AL\nCo, the MO response has a linear dependence with the Co thickness, indicative\nof a continuous-film-like MO behavior.",
        "positive": "Emergence of topologically protected states in MoTe$_{2}$ Weyl semimetal\n  with layer stacking order: Electronic tunability in crystals with weakly-bound layers can be achieved\nthrough layer stacking order. One such example is MoTe$_2$, where the\nlow-temperature orthorhombic T$_d$ phase is topological and host to Weyl\nquasiparticles. The transition mechanism to the non-trivial topology is\nelucidated by single crystal neutron diffraction. Upon cooling from the\nmonoclinic 1T$\\prime$ to the T$_d$ phase, diffuse scattering accompanies the\ntransition, arising from random, in-plane layer displacements, and dissipates\nupon entering the T$_d$ phase. Diffuse scattering is observed only in the H0L\nplane due to irreversible layer shifts along the c-axis that break the\ncentrosymmetry of the monoclinic lattice."
    },
    {
        "anchor": "Effect of interfacial Dzyaloshinskii-Moriya interaction on polarized\n  neutrons reflection: The antisymmetric Dzyaloshinskii-Moriya interaction (DMI) in\nnoncentrosymmetric systems leads to various nonuniform chiral magnetic\ntextures. Polarized neutron scattering is a powerful method for investigation\nsuch chiral distributions. The most used technique is a small-angle neutrons\nscattering (SANS). Multilayered magnetic films with the interface induced DMI\n(iDMI) can't be investigated by SANS because of their small volume. The\nappropriate technique is a polarized neutron reflectometry. Within the\nframework of the continuum theory of micromagnetics, we explore the impact of\nthe iDMI on the polarized neutrons reflection from multilayers with random\nmagnetic anisotropy. It is shown that the iDMI gives rise to a\npolarization-dependent asymmetric term in the reflection.",
        "positive": "Detecting charge transfer at defects in 2D materials with electron\n  ptychography: Charge transfer between atoms is fundamental to chemical bonding but has\nremained very challenging to detect directly in real space. Atomic-resolution\nimaging of charge density is not sufficient by itself, as the change in the\ndensity due to bonding is very subtle compared to the total local charge\ndensity. Sufficiently high sensitivity, precision and accuracy are required,\nwhich we demonstrate here for the detection of charge transfer at defects in\ntwo-dimensional WS\\textsubscript{2} via high-speed electron ptychography and\nits ability to correct errors due to residual lens aberrations."
    },
    {
        "anchor": "Antiferromagnetic Dimers of Ni(II) in the S=1 Spin-Ladder\n  Na_2Ni_2(C_2O_4)_3(H_2O)_2: We report the synthesis, crystal structure and magnetic properties of the S=1\n2-leg spin-ladder compound Na_2Ni_2(C_2O_4)_3(H_2O)_2. The magnetic properties\nwere examined by magnetic susceptibility and pulsed high field magnetization\nmeasurements. The magnetic excitations have been measured in high field high\nfrequency ESR. Although the Ni(II) ions form structurally a 2-leg ladder, an\nisolated dimer model consistently describes the observations very well. The\nanalysis of the temperature dependent magnetization data leads to a magnetic\nexchange constant of J=43 K along the rungs of the ladder and an average value\nof the g-factor of 2.25. From the ESR measurements, we determined the single\nion anisotropy to D=11.5 K. The validity of the isolated dimer model is\nsupported by Quantum Monte Carlo calculations, performed for several ratios of\ninterdimer and intradimer magnetic exchange and taking into account the\nexperimentally determined single ion anisotropy. The results can be understood\nin terms of the different coordination and superexchange angles of the oxalate\nligands along the rungs and legs of the 2-leg spin ladder.",
        "positive": "Commensurate structures in twisted transition metal dichalcogenide\n  heterobilayers: A major theoretical challenge of studying twisted transition metal\ndichalcogenide (TMD) bilayers is that the unit cell of such structures is very\nlarge and therefore difficult to address using first-principles methods.\nHowever, twisted TMD bilayers form moir\\'e patterns, which consist of regions\nof commensurate stacking, either smoothly interpolated into one another or\nseparated by sharp domain walls. In this paper, we study twisted TMD bilayers\nby studying the properties of the constituent commensurate structures. Using\ndensity functional theory (DFT), we compute band structures for\ncommensurately-stacked MoS$_2$/WS$_2$ and MoSe$_2$/WSe$_2$ bilayers in both\n$0^\\circ$ and $60^\\circ$ orientations, and we highlight variations in band\nstructures across different commensurate geometries. These band structure\nvariations arise from diverse factors such as metal atom asymmetry between\nlayers (Mo vs. W), differences in interlayer hybridization, and Brillouin zone\nalignment. We comment on the consequences of such band structure differences\nfor optical experiments and on the effects of strain on moir\\'e pattern\nelectronic structure."
    },
    {
        "anchor": "Ab initio multi-scale modeling of ferroelectrics: The case of PbTiO3: We report an ab initio multi-scale study of lead titanate using the Deep\nPotential (DP) models, a family of machine learning-based atomistic models,\ntrained on first-principles density functional theory data, to represent\npotential and polarization surfaces. Our approach includes anharmonic effects\nbeyond the limitations of reduced models and of the linear approximation for\nthe polarization. The calculated enthalpy, spontaneous polarization, specific\nheat and dielectric susceptibility agree well with experiments on single\ncrystals. In addition, we study how the free energy depends on the polarization\nwith enhanced sampling methods, further supporting the first-order and\norder-disorder character of the transition. The latter is evidenced by\npersistence of local dipoles above the transition temperature. The simulated\nfree energy surface as a function of the global polarization leads to a\nLandau-Devonshire theory of the single domain crystal.",
        "positive": "Internal Interface Strains Effects on UO2/U3O7 Oxidation Behaviour: The growth of a U3O7 oxide layer during the anionic oxidation of UO2 pellets\ninduced very important mechanical stresses due to the crystallographic lattice\nparameters differences between UO2 and its oxide. These stresses, combined with\nthe chemical processes of oxidation, can lead to the cracking of the system,\ncalled chemical fragmentation. We study the crystallographic orientation of the\noxide lattice growing at the surface of UO2, pointing the fact that epitaxy\nrelations at interface govern the coexistence of UO2 and U3O7. In this work,\nseveral results are given: - Determination of the epitaxy relations between the\nsubstrate and its oxide thanks to the Bollmann's method; epitaxy strains are\ndeduced. - Study of the coexistence of different domains in the U3O7\n(crystallographic compatibility conditions at the interface between two phases:\nHadamard conditions). - FEM simulations of a multi-domain U3O7 connected to a\nUO2 substrate explain the existence of a critical thickness of U3O7 layer."
    },
    {
        "anchor": "Percolation Modeling of Self-Damaging of Composite Materials: We propose the concept of autonomous self-damaging in \"smart\" composite\nmaterials, controlled by activation of added nanosize \"damaging\" capsules.\nPercolation-type modeling approach earlier applied to the related concept of\nself-healing materials, is used to investigate the behavior of the initial\nmaterial's fatigue. We aim at achieving a relatively sharp drop in the\nmaterial's integrity after some initial limited fatigue develops in the course\nof the sample's usage. Our theoretical study considers a two-dimensional\nlattice model and involves Monte Carlo simulations of the connectivity and\nconductance in the high-connectivity regime of percolation. We give several\nexamples of local capsule-lattice and capsule-capsule activation rules and show\nthat the desired self-damaging property can only be obtained with rather\nsophisticated \"smart\" material's response involving not just damaging but also\nhealing capsules.",
        "positive": "How the SiC substrate impacts graphene atomic and electronic structures: Graphene, the two-dimensional form of carbon presents outstanding electronic\nand transport properties. This gives hope for the development of applications\nin nanoelectronics. However, for industrial purpose, graphene has to be\nsupported by a substrate. We focus here on the graphene-on-SiC system to\ndiscuss how the SiC substrate interacts with the graphene layer and to show the\neffect of the interface on graphene atomic and electronic structures."
    },
    {
        "anchor": "X-ray absorption study of the ferromagnetic Cu moment at the\n  $\\mathbf{{YBa_2Cu_3O_7}/{La_{2/3}Ca_{1/3}MnO_3}}$ interface and the variation\n  of its exchange interaction with the Mn moment: With x-ray absorption spectroscopy and polarized neutron reflectometry we\nstudied how the magnetic proximity effect at the interface between the cuprate\nhigh-$T_C$ superconductor $\\mathrm{YBa_2Cu_3O_7}$ (YBCO) and the ferromagnet\n$\\mathrm{La_{2/3}Ca_{1/3}MnO_3}$ (LCMO) is related to the electronic and\nmagnetic properties of the LCMO layers. In particular, we explored how the\nmagnitude of the ferromagnetic Cu moment on the YBCO side depends on the\nstrength of the antiferromagnetic (AF) exchange coupling with the Mn moment on\nthe LCMO side. We found that the Cu moment remains sizeable if the AF coupling\nwith the Mn moments is strongly reduced or even entirely suppressed. The\nferromagnetic order of the Cu moments thus seems to be intrinsic to the\ninterfacial CuO$_2$ planes and related to a weakly ferromagnetic intra-planar\nexchange interaction. The latter is discussed in terms of the partial\noccupation of the Cu $3d_{3z^2-r^2}$ orbitals, which occurs in the context of\nthe so-called orbital reconstruction of the interfacial Cu ions.",
        "positive": "Caloric Effects in Methylammonium Lead Iodide from Molecular Dynamics\n  Simulations: Organic-inorganic hybrid perovskite architecture could serve as a robust\nplatform for materials design to realize functionalities beyond photovoltaic\napplications. We explore caloric effects in organometal halide perovskites,\ntaking methylammonium lead iodide (MAPbI$_3$) as an example, using all-atom\nmolecular dynamics simulations with a first-principles based interatomic\npotential. The adiabatic thermal change is estimated directly by introducing\ndifferent driving fields in the simulations. We find that MAPbI$_3$ exhibits\nboth electrocaloric and mechanocaloric effects at room temperature. Local\nstructural analysis reveals that the rearrangement of molecular cations in\nresponse to electric and stress fields is responsible for the caloric effects.\nThe enhancement of caloric response could be realized through strain\nengineering and chemical doping."
    },
    {
        "anchor": "Phonons of Metallic Vicinal Surfaces: We present an analysis of the vibrational dynamics of metal vicinal surfaces\nusing the embedded atom method to describe the interaction potential and both a\nreal space Green's function method and a slab method to calculate the phonons.\n  We report two main general characteristics : a global shift of the surface\nvibrational density of states resulting from a softening of the force field.\nThe latter is a direct result of the reduction of coordination for the\ndifferent type of surface atoms; and an appearance of high frequency modes\nabove the bulk band, resulting from a stiffening of the force field near the\nstep atom. The latter is due to a rearrangement of the atomic positions during\nthe relaxation of the surface atoms yielding a large shortening of the nearest\nneighbor distances near the step atoms.",
        "positive": "Autonomy and Singularity in Dynamic Fracture: The recently developed weakly nonlinear theory of dynamic fracture predicts\n$1/r$ corrections to the standard asymptotic linear elastic $1/\\sqrt{r}$\ndisplacement-gradients, where $r$ is measured from the tip of a tensile crack.\nWe show that the $1/r$ singularity does not automatically conform with the\nnotion of autonomy (autonomy means that any crack tip nonlinear solution is\nuniquely determined by the surrounding linear elastic $1/\\sqrt{r}$ fields) and\nthat it does not automatically satisfy the resultant Newton's equation in the\ncrack parallel direction. We show that these two properties are interrelated\nand that by requiring that the resultant Newton's equation is satisfied,\nautonomy of the $1/r$ singular solution is retained. We further show that the\nresultant linear momentum carried by the $1/r$ singular fields vanishes\nidentically. Our results, which reveal the physical and mathematical nature of\nthe new solution, are in favorable agreement with recent near tip measurements."
    },
    {
        "anchor": "Rich Ground State Chemical Ordering in Nanoparticles: Exact Solution of\n  a Model for Ag-Au Clusters: We show that nanoparticles can have very rich ground state chemical order.\nThis is illustrated by determining the chemical ordering of Ag-Au 309-atom\nMackay icosahedral nanoparticles. The energy of the nanoparticles is described\nusing a cluster expansion model, and a Mixed Integer Programming (MIP) approach\nis used to find the exact ground state configurations for all stoichiometries.\nThe chemical ordering varies widely between the different stoichiometries, and\ndisplay a rich zoo of structures with non-trivial ordering.",
        "positive": "Density functional theory study of vacancy induced magnetism in\n  Li$_{3}$N: The effect of lithium vacancies in the hexagonal structure of\n$\\alpha-$Li$_3$N, is studied within the framework of density functional theory.\nVacancies ($\\square$) substituting for lithium in\n$\\alpha-$Li$_2$(Li$_{1-x}\\square_x$)N are treated within the coherent potential\napproximation as alloy components. According to our results long range\nN($p$)-ferromagnetism ($\\sim 1$ $\\mu_B$) sets in for vacancy substitution\nwithin the [Li$_2$N] layers ($x \\ge 0.7$) with no significant change in unit\ncell dimensions. By total energies differences we established that in-plane\nexchange couplings are dominant. Vacancies substituting inter-plane Li, leads\nto a considerable structural collapse ($c/a \\approx 0.7$) and no magnetic\nmoment formation."
    },
    {
        "anchor": "Effect of chemical and hydrostatic pressure on the coupled\n  magnetostructural transition of Ni-Mn-In Heusler alloys: Ni-Mn-In magnetic shape-memory Heusler alloys exhibit generally a large\nthermal hysteresis at their first-order martensitic phase transition which\nhinder a technological application in magnetic refrigeration. By optimizing the\nCu content in Ni$_2$Cu$_x$Mn$_{1.4-x}$In$_{0.6}$, we obtained a thermal\nhysteresis of the martensitic phase transition in\nNi$_{2}$Cu$_{0.2}$Mn$_{1.2}$In$_{0.6}$ of only 6 K. We can explain this very\nsmall hysteresis by an almost perfect habit plane at the interface of\nmartensite and austenite phases. Application of hydrostatic pressure does not\nreduce the hysteresis further, but shifts the martensitic transition close to\nroom temperature. The isothermal entropy change does not depend on warming or\ncooling protocols and is pressure independent. Experiments in pulsed-magnetic\nfields on Ni$_{2}$Cu$_{0.2}$Mn$_{1.2}$In$_{0.6}$ find a reversible\nmagnetocaloric effect with a maximum adiabatic temperature change of -13 K.",
        "positive": "Non-trivial Surface-band Dispersion on Bi(111): We performed angle-resolved photoelectron spectroscopy of the Bi(111) surface\nto demonstrate that this surface support edge states of non-trivial topology.\nAlong the $\\bar{\\Gamma}\\bar{M}$-direction of the surface Brillouin zone, a\nsurface-state band disperses from the projected bulk valence bands at\n$\\bar{\\Gamma}$ to the conduction bands at $\\bar{M}$ continuously, indicating\nthe non-trivial topological order of three-dimensional Bi bands. We ascribe\nthis finding to the absence of band inversion at the $L$ point of the bulk Bi\nBrillouin zone. According to our analysis, a modification of tight-binding\nparameters can account for the non-trivial band structure of Bi without any\nother significant change on other physical properties."
    },
    {
        "anchor": "Analytic binary alloy volume-concentration relations and the deviation\n  from Zen`s law: Alloys expand or contract as concentrations change, and the resulting\nrelationship between atomic volume and alloy content is an important property\nof the solid. While a well-known approximation posits that the atomic volume\nvaries linearly with concentration (Zen`s law), the actual variation is more\ncomplicated. Here we use an apparent size of the solute (solvent) atom and the\nelasticity to derive explicit analytical expressions for the atomic volume of\nbinary solid alloys. Two approximations, continuum and terminal, are proposed.\nDeviations from Zen`s law are studied for 22 binary alloy systems.",
        "positive": "B1-B2 phase transition in MgO at ultra-high static pressure: Studies of the behaviour of solids at ultra-high pressures, those beyond 200\nGPa, contribute to our fundamental understanding of materials properties and\nallow an insight into the processes happening at such extreme conditions\nrelevant for terrestrial and extra-terrestrial bodies. The behaviour of\nmagnesium oxide, MgO, is of a particular importance, as it is believed to be a\nmajor phase in the Earth lower mantle and the interior of super-Earth planets.\nHere we report the results of studies of MgO at ultra-high static pressures up\nto ca. 660 GPa using the double-stage diamond anvil cell technique with\nsynchrotron X-ray diffraction. We observed the B1-B2 phase transition in the\npressure interval from 429(10) GPa to 562(10) GPa setting an unambiguous\nreference mark for the B1-B2 transition in MgO at room temperature. Our\nobservations allow constraining theoretical predictions and results of\navailable so far dynamic compression experiments."
    },
    {
        "anchor": "Observation of high-temperature quantum anomalous Hall regime in\n  intrinsic MnBi$_2$Te$_4$/Bi$_2$Te$_3$ superlattice: The quantum anomalous Hall effect is a fundamental transport response of a\ntopologically non-trivial system in zero magnetic field. Its physical origin\nrelies on the intrinsically inverted electronic band structure and\nferromagnetism, and its most consequential manifestation is the\ndissipation-free flow of chiral charge currents at the edges that can\npotentially transform future quantum electronics. Here we report a previously\nunknown Berry-curvature-driven anomalous Hall regime ('Q-window') at\nabove-Kelvin temperatures in the magnetic topological bulk crystals where\nthrough growth Mn ions self-organize into a period-ordered\nMnBi$_2$Te$_4$/Bi$_2$Te$_3$ superlattice. Robust ferromagnetism of the\nMnBi$_2$Te$_4$ monolayers opens a large surface gap, and anomalous Hall\nconductance reaches an $e^2/h$ quantization plateau when the Fermi level is\ntuned into this gap within a Q-window in which the anomalous Hall conductance\nfrom the bulk is to a high precision zero. The quantization in this new regime\nis not obstructed by the bulk conduction channels and thus should be present in\na broad family of topological magnets.",
        "positive": "Towards a Multi-Objective Optimization of Subgroups for the Discovery of\n  Materials with Exceptional Performance: Artificial intelligence (AI) can accelerate the design of materials by\nidentifying correlations and complex patterns in data. However, AI methods\ncommonly attempt to describe the entire, immense materials space with a single\nmodel, while it is typical that different mechanisms govern the materials\nbehaviors across the materials space. The subgroup-discovery (SGD) approach\nidentifies local rules describing exceptional subsets of data with respect to a\ngiven target. Thus, SGD can focus on mechanisms leading to exceptional\nperformance. However, the identification of appropriate SG rules requires a\ncareful consideration of the generality-exceptionality tradeoff. Here, we\ndiscuss challenges to advance the SGD approach in materials science and analyse\nthe tradeoff between exceptionality and generality based on a Pareto front of\nSGD solutions."
    },
    {
        "anchor": "Fermi surface reconstruction due to the orthorhombic distortion in Dirac\n  semimetal YbMnSb$_2$: Dirac semi-metal with magnetic atoms as constituents delivers an interesting\nplatform to investigate the interplay of Fermi surface (FS) topology, electron\ncorrelation, and magnetism. One such family of semi-metal is YbMn$Pn_2$ ($Pn$ =\nSb, Bi), which is being actively studied due to the intertwined spin and charge\ndegrees of freedom. In this Letter, we investigate the relationship between the\nmagnetic/crystal structures and FS topology of YbMnSb$_2$ using single crystal\nx-ray diffraction, neutron scattering, magnetic susceptibility,\nmagnetotransport measurement and complimentary DFT calculation. Contrary to\nprevious reports, the x-ray and neutron diffraction reveal that YbMnSb$_2$\ncrystallizes in an orthorhombic $Pnma$ structure with notable anti-phase\ndisplacement of the magnetic Mn ions that increases in magnitude upon cooling.\nFirst principles DFT calculation reveals a reduced Brillouin zone and more\nanisotropic FS of YbMnSb$_2$ compared to YbMnBi$_2$ as a result of the\northorhombicity. Moreover, the hole type carrier density drops by two orders of\nmagnitude as YbMnSb$_2$ orders antiferromagnetically indicating band folding in\nmagnetic ordered state. In addition, the Landau level fan diagram yields a\nnon-trivial nature of the SdH quantum oscillation frequency arising from the\nDirac-like Fermi pocket. These results imply that YbMnSb$_2$ is an ideal\nplatform to explore the interplay of subtle lattice distortion, magnetic order,\nand topological transport arising from relativistic quasiparticles.",
        "positive": "Identifying substitutional oxygen as a prolific point defect in\n  monolayer transition metal dichalcogenides with experiment and theory: Chalcogen vacancies are considered to be the most abundant point defects in\ntwo-dimensional (2D) transition-metal dichalcogenide (TMD) semiconductors, and\npredicted to result in deep in-gap states (IGS). As a result, important\nfeatures in the optical response of 2D-TMDs have typically been attributed to\nchalcogen vacancies, with indirect support from Transmission Electron\nMicroscopy (TEM) and Scanning Tunneling Microscopy (STM) images. However, TEM\nimaging measurements do not provide direct access to the electronic structure\nof individual defects; and while Scanning Tunneling Spectroscopy (STS) is a\ndirect probe of local electronic structure, the interpretation of the chemical\nnature of atomically-resolved STM images of point defects in 2D-TMDs can be\nambiguous. As a result, the assignment of point defects as vacancies or\nsubstitutional atoms of different kinds in 2D-TMDs, and their influence on\ntheir electronic properties, has been inconsistent and lacks consensus. Here,\nwe combine low-temperature non-contact atomic force microscopy (nc-AFM), STS,\nand state-of-the-art ab initio density functional theory (DFT) and GW\ncalculations to determine both the structure and electronic properties of the\nmost abundant individual chalcogen-site defects common to 2D-TMDs.\nSurprisingly, we observe no IGS for any of the chalcogen defects probed. Our\nresults and analysis strongly suggest that the common chalcogen defects in our\n2D-TMDs, prepared and measured in standard environments, are substitutional\noxygen rather than vacancies."
    },
    {
        "anchor": "Molecular Tuning of the Magnetic Response in Organic Semiconductors: The tunability of high-mobility organic semi-conductors (OSCs) holds great\npromise for molecular spintronics. In this study, we show this extreme\nvariability - and therefore potential tunability - of the molecular\ngyromagnetic coupling (\"g-\") tensor with respect to the geometric and\nelectronic structure in a much studied class of OSCs. Composed of a structural\ntheme of phenyl- and chalcogenophene (group XVI element containing,\nfive-membered) rings and alkyl functional groups, this class forms the basis of\nseveral intensely studied high-mobility polymers and molecular OSCs. We show\nhow in this class the g-tensor shifts, $\\Delta g$, are determined by the\neffective molecular spin-orbit coupling (SOC), defined by the overlap of the\natomic spin-density and the heavy atoms in the polymers. We explain the\ndramatic variations in SOC with molecular geometry, chemical composition,\nfunctionalization, and charge life-time using a first-principles theoretical\nmodel based on atomic spin populations. Our approach gives a guide to tuning\nthe magnetic response of these OSCs by chemical synthesis.",
        "positive": "Temperature-dependent classical phonons from efficient non-dynamical\n  simulations: We present a rigorous and efficient approach to the calculation of classical\nlattice-dynamical quantities from simulations that do not require an explicit\nsolution of the time evolution. We focus on the temperature-dependent\nvibrational spectrum. We start from the moment expansion of the relevant\ntime-correlation function for a many-body system, and show that it can be\nconveniently rewritten by using a basis in which the low-order moments are\ndiagonal. This allows us to compute the main spectral features (e.g., position\nand width of the phonon peaks) from thermal averages available from any\nstatistical simulation. We successfully apply our method to a model system that\npresents a structural transition and strongly temperature-dependent phonons.\nOur theory clarifies the status of previous heuristic schemes to estimate\nphonon frequencies."
    },
    {
        "anchor": "Optical Hall conductivity of systems with gapped spectral nodes: We calculate the optical Hall conductivity within the Kubo formalism for\nsystems with gapped spectral nodes, where the latter have a power-law\ndispersion with exponent n. The optical conductivity is proportional to n and\nthere is a characteristic logarithmic singularity as the frequency approaches\nthe gap energy. The optical Hall conductivity is almost unaffected by thermal\nfluctuations and disorder for n=1, whereas disorder has a stronger effect on\ntransport properties if n=2.",
        "positive": "Reply to the correspondence: \"On the fracture toughness of bioinspired\n  ceramic materials\": This is a reply to the correspondence of Prof. Robert Ritchie: \"On the\nfracture toughness of bioinspired ceramic materials\", submitted to Nature\nMaterials, which discusses the fracture toughness values of the following\npapers: Bouville, F., Maire, E., Meille, S., Van de Moort\\`ele, B., Stevenson,\nA. J., & Deville, S. (2014). Strong, tough and stiff bioinspired ceramics from\nbrittle constituents. Nature Materials, 13(5), 508-514 and Le Ferrand, H.,\nBouville, F., Niebel, T. P., & Studart, A. R. (2015). Magnetically assisted\nslip casting of bioinspired heterogeneous composites. Nature Materials, 14(11),\n1172-1172."
    },
    {
        "anchor": "Manipulating Semicrystalline Polymers in Confinement: Because final properties of nanoscale polymeric structures are largely\ndetermined by the solid-state microstructure of the confined polymer, it is\nimperative not only to understand how the microstructure of polymers develops\nunder nanoscale confinement but also to establish means to manipulate it. Here\nwe present a series of processing strategies, adapted from methods used in bulk\npolymer processing, that allow to control the solidification of polymer\nnanostructures. Firstly, we show that supramolecular nucleating agents can be\nreadily used to modify the crystallization kinetics of confined poly(vinylidene\nfluoride) (PVDF). In addition, we demonstrate that microstructural features\nthat are not traditionally affected by nucleating agents, such as the\norientation of crystals, can be tuned with the crystallization temperature\napplied. Interestingly, we also show that high crystallization temperatures and\nlong annealing periods induce the formation of the modification of PVDF, hence\nenabling the simple production of ferro/piezoelectric nanostructures. We\nanticipate that the approaches presented here can open up a plethora of new\npossibilities for the processing of polymer-based nanostructures with tailored\nproperties and functionalities.",
        "positive": "Disconnection-Mediated Twin/Twin-Junction Migration in FCC metals: We present the results of novel, time-resolved, in situ HRTEM observations,\nmolecular dynamics (MD) simulations, and disconnection theory that elucidate\nthe mechanism by which the motion of grain boundaries (GBs) in polycrystalline\nmaterials are coupled through disconnection motion/reactions at/adjacent to GB\ntriple junctions (TJs). We focus on TJs composed of a pair of coherent twin\nboundaries (CTBs) and a {\\Sigma}9 GB. As for all GBs, disconnection theory\nimplies that multiple modes/local mechanisms for CTB migration are possible and\nthat the mode selection is affected by the nature of the driving force for\nmigration. While we observe (HRTEM and MD) CTB migration through the motion of\npure steps driven by chemical potential jump, other experimental observations\n(and our simulations) show that stress-driven CTB migration occurs through the\nmotion of disconnections with a non-zero Burgers vector; these are pure-step\nand twinning-partial CTB migration mechanisms. Our experimental observations\nand simulations demonstrate that the motion of a GB drags its delimiting TJ and\nmay force the motion of the other GBs meeting at the TJ. Our experiments and\nsimulations focus on two types of TJs composed of a pair of CTBs and a\n{\\Sigma}9 GB; a 107{\\deg} TJ readily migrates while a 70{\\deg} TJ is immobile\n(experiment, simulation) in agreement with our disconnection theory even though\nthe intrinsic mobilities of the constituent GBs do not depend on TJ-type. We\nalso demonstrate that disconnections may be formed at TJs (chemical potential\njump/stress driven) and at GB/free surface junctions (stress-driven)."
    },
    {
        "anchor": "A simple descriptor for energetics at fcc-bcc metal interfaces: We have developed a new and user-friendly interface energy calculation method\nthat avoids problems deriving from numerical differences between bulk and slab\ncalculations, such as the number of k points along the direction perpendicular\nto the interface. We have applied this to 36 bcc-fcc metal interfaces in the\n(100) orientation and found a clear dependence of the interface energy on the\ndifference between the work functions of the two metals, on the one hand, and\nthe total number of d electrons on the other. Greater mechanical deformations\nwere observed in fcc crystals than in their bcc counterparts. For each bcc\nmetal, the interface energy was found to follow the position of its d band,\nwhereas the same was not observed for fcc.",
        "positive": "High-quality, large-grain MoS2 films grown on 100 mm sapphire substrates\n  using a novel molybdenum precursor: Two-dimensional MoS2 is a crystalline semiconductor with high potential for\nnumerous technologies. Research in recent years has sought to exploit the\ndirect band gap and high carrier mobility properties of monolayer MoS2 for\nfunctional applications. To date, the production of MoS2 has remained at the\nresearch level and samples are usually synthesized in small quantities using\nsmall yield, expensive techniques. In order to realize scalable MoS2-based\ntechnology, large-area, high-quality and affordable MoS2 wafers must become\navailable. Here we report on MoS2 films grown on 100 mm sapphire wafers by a\nchemical vapor deposition process utilizing hydrogen sulfide and molybdenum\nprecursor mixtures consisting of Na2MoO4 and NaCl. The grains of these films\nare faceted, large-area, on the order of 1-75 microns in length on edge. Growth\nconditions are identified that yield monolayer MoS2 films. Raman spectroscopy\nshows an E2g and A1g peak separation of 17.9-19.1 cm-1. Photoluminescence\nspectroscopy shows that annealing the films post-growth suppresses trion\nemission. X-ray photoelectron spectroscopy of the annealed films shows an in\nincrease in the S:Mo concentration ratio from 1.90:1.00 to 2.09:1.00."
    },
    {
        "anchor": "Atomic-scale Oxygen-mediated Etching of 2D MoS$_2$ and MoTe$_2$: Some of the materials are more affected by oxidation than others. To\nelucidate the oxidation-induced degradation mechanisms in transition metal\nchalcogenides, the chemical effects in single layer MoS$_2$ and MoTe$_2$ were\nstudied in situ in an electron microscope under controlled low-pressure oxygen\nenvironments at room temperature.Oxidation is the main cause of degradation of\nmany two-dimensional materials, including transition metal dichalcogenides,\nunder ambient conditions. MoTe$_2$ is found to be reactive to oxygen, leading\nto significant degradation above a pressure of 1$\\times 10^{-7}$ torr.\nCuriously, the common hydrocarbon contamination found on practically all\nsurfaces accelerates the damage rate significantly, by up to a factor of forty.\nIn contrast to MoTe$_2$, MoS$_2$ is found to be inert under oxygen environment,\nwith all observed structural changes being caused by electron irradiation only,\nleading to well-defined pores with high proportion of molybdenum\nnanowire-terminated edges. Using density functional theory calculations, a\nfurther atomic-scale mechanism leading to the observed oxygen-related\ndegradation in MoTe$_2$ is proposed and the role of the carbon in the etching\nis explored. Together, the results provide an important insight into the\noxygen-related deterioration of two-dimensional materials under ambient\nconditions relevant in many fields.",
        "positive": "Bridging Nano and Micro-scale X-ray Tomography for Battery Research by\n  Leveraging Artificial Intelligence: X-ray Computed Tomography (X-ray CT) is a well-known non-destructive imaging\ntechnique where contrast originates from the materials' absorption\ncoefficients. Novel battery characterization studies on increasingly\nchallenging samples have been enabled by the rapid development of both\nsynchrotron and laboratory-scale imaging systems as well as innovative analysis\ntechniques. Furthermore, the recent development of laboratory nano-scale CT\n(NanoCT) systems has pushed the limits of battery material imaging towards\nvoxel sizes previously achievable only using synchrotron facilities. Such\nsystems are now able to reach spatial resolutions down to 50 nm. Given the\nnon-destructive nature of CT, in-situ and operando studies have emerged as\npowerful methods to quantify morphological parameters, such as tortuosity\nfactor, porosity, surface area, and volume expansion during battery operation\nor cycling. Combined with powerful Artificial Intelligence (AI)/Machine\nLearning (ML) analysis techniques, extracted 3D tomograms and battery-specific\nmorphological parameters enable the development of predictive physics-based\nmodels that can provide valuable insights for battery engineering. These models\ncan predict the impact of the electrode microstructure on cell performances or\nanalyze the influence of material heterogeneities on electrochemical responses.\nIn this work, we review the increasing role of X-ray CT experimentation in the\nbattery field, discuss the incorporation of AI/ML in analysis, and provide a\nperspective on how the combination of multi-scale CT imaging techniques can\nexpand the development of predictive multiscale battery behavioral models."
    },
    {
        "anchor": "Scavenging effect on plasma oxidized Gd$_2$O$_3$ grown by high pressure\n  sputtering on Si and InP substrates: In this work, we analyze the scavenging effect of titanium gates on metal\ninsulator semiconductor capacitors composed of gadolinium oxide as dielectric\nmaterial deposited on Si and InP substrates. The Gd$_2$O$_3$ film was grown by\nhigh pressure sputtering from a metallic target followed by an in situ plasma\noxidation. The thickness of the Ti film was varied between 2.5 and 17 nm and\nwas capped with a Pt layer. For the devices grown on Si, a layer of 5 nm of Ti\ndecreases the capacitance equivalent thickness from 2.3 to 1.9 nm without\ncompromising the leakage current (1e-4 A cm$^{-2}$ at Vgate equal to 1 V).\nThinner Ti has little impact on device performance, while 17 nm of Ti produces\nexcessive scavenging. For InP capacitors, the scavenging effect is also\nobserved with a decrease in the capacitance equivalent thickness from 2.5 to\n1.9 nm (or an increase in the accumulation capacitance after the annealing from\n1.4 to 1.7-1.8 uF cm$^{-2}$). The leakage current density remains under 1e-2 A\ncm$^{-2}$ at Vgate equal to 1.5 V. For these devices, a severe flatband voltage\nshift with frequency is observed. This can be explained by a very high\ninterface trap state density (in the order of 1e13-1e14 eV$^{-1}$ cm$^{-2}$).",
        "positive": "Self-compensation in manganese-doped ferromagnetic semiconductors: We present a theory of interstitial Mn in Mn-doped ferromagnetic\nsemiconductors. Using density-functional theory, we show that under the\nnon-equilibrium conditions of growth, interstitial Mn is easily formed near the\nsurface by a simple low-energy adsorption pathway. In GaAs, isolated\ninterstitial Mn is an electron donor, each compensating two substitutional Mn\nacceptors. Within an impurity-band model, partial compensation promotes\nferromagnetic order below the metal-insulator transition, with the highest\nCurie temperature occurring for 0.5 holes per substitutional Mn."
    },
    {
        "anchor": "Yield precursor dislocation avalanches in small crystals: the\n  irreversibility transition: The transition from elastic to plastic deformation in crystalline metals\nshares history dependence and scale-invariant avalanche signature with other\nnon-equilibrium systems under external loading: dilute colloidal suspensions,\nplastically-deformed amorphous solids, granular materials, and\ndislocation-based simulations of crystals. These other systems exhibit\ntransitions with clear analogies to work hardening and yield stress, with many\ntypically undergoing purely elastic behavior only after 'training' through\nrepeated cyclic loading; studies in these other systems show a power law\nscaling of the hysteresis loop extent and of the training time as the peak load\napproaches a so-called reversible-irreversible transition (RIT). We discover\nhere that deformation of small crystals shares these key characteristics:\nyielding and hysteresis in uniaxial compression experiments of\nsingle-crystalline Cu nano- and micro-pillars decay under repeated cyclic\nloading. The amplitude and decay time of the yield precursor avalanches diverge\nas the peak stress approaches failure stress for each pillar, with a power law\nscaling virtually equivalent to RITs in other nonequilibrium systems.",
        "positive": "Towards smooth (010) beta-Ga2O3 films homoepitaxially grown by plasma\n  assisted molecular beam epitaxy: The impact of substrate offcut and\n  metal-to-oxygen flux ratio: Smooth interfaces and surfaces are beneficial for most (opto)electronic\ndevices based on thin films and their heterostructures. For example, smoother\ninterfaces in (010) beta-Ga2O3/(AlxGa1-x)2O3 heterostructures, whose roughness\nis ruled by that of the Ga2O3 layer, can enable higher mobility 2DEGs by\nreducing interface roughness scattering. To this end we experimentally prove\nthat a substrate offcut along the [001] direction allows to obtain smooth\nbeta-Ga2O3 layers in (010)-homoepitaxy under metal-rich conditions. Applying\nIn-mediated metal-exchange catalysis (MEXCAT) in molecular beam epitaxy at high\nsubstrate temperatures (Tg = 900 {\\deg}C) we compare the morphology of layers\ngrown on (010)-oriented substrates with different unintentional offcuts. The\nlayer roughness is generally ruled by (i) (110) and (-110)-facets visible as\nelongated features along the [001] direction (rms < 0.5 nm), and (ii) trenches\n(5-10 nm deep) orthogonal to [001]. We show that an unintentional substrate\noffcut of only 0.1{\\deg} almost oriented along the [001] direction suppresses\nthese trenches resulting in a smooth morphology with a roughness exclusively\ndetermined by the facets, i.e., rms 0.2 nm. Since we found the facet-and-trench\nmorphology in layers grown by MBE with and without MEXCAT, we propose that the\ngeneral growth mechanism for (010)-homoepitaxy is ruled by island growth whose\ncoalescence results in the formation of the trenches. The presence of a\nsubstrate offcut in the [001] direction can allow for step-flow growth or\nisland nucleation at the step edges, which prevents the formation of trenches.\nMoreover, we give experimental evidence for a decreasing surface diffusion\nlength or increasing nucleation density with decreasing metal-to-oxygen flux\nratio. Based on our results we can rule-out step bunching as cause of the\ntrench formation as well as a surfactant-effect of indium during MEXCAT."
    },
    {
        "anchor": "Multiferroic coupling in nanoscale BiFeO3: Using the results of x-ray and neutron diffraction experiments, we show that\nthe ferroelectric polarization, in ~22 nm particles of BiFeO3, exhibits a jump\nby ~30% around the magnetic transition point T_N (~635 K) and a suppression by\n~7% under 5T magnetic field at room temperature (<<T_N). These results confirm\npresence of strong multiferroic coupling even in nanoscale BiFeO3 and thus\ncould prove to be quite useful for applications based on nanosized devices of\nBiFeO3.",
        "positive": "Surface Reactivity Enhancement by O2 Dissociation on a Single-layer MgO\n  Film Deposited on Metal Substrate: Improving reactivity on an insulating surface is crucial due to their\nimportant applications in surface catalytic reactions. In this work, we carried\nout first-principles calculations to investigate the adsorption of O2 on a\nsingle-layer MgO(100) film deposited on metal substrate. The adsorption\nconfigurations, reaction pathways, molecular dynamics simulations, and\nelectronic properties are reported. We reveal that O2 can completely dissociate\non the surface, which is in sharp contrast to that on MgO(100) films thicker\nthan one monolayer. The dissociated O2 tends to penetrate into the interfacial\nregion, behaving like a switch to trigger subsequent chemical reactions. As an\nexample, the interplay between water and the interfacial oxygen results in the\nformation of hydroxyl radicals. This study paves an avenue to accomplish the\ndesired surface catalytic reactions, especially those involving oxygen."
    },
    {
        "anchor": "Probing the Interatomic Potential of Solids by Strong-Field Nonlinear\n  Phononics: Femtosecond optical pulses at mid-infrared frequencies have opened up the\nnonlinear control of lattice vibrations in solids. So far, all applications\nhave relied on second order phonon nonlinearities, which are dominant at field\nstrengths near 1 MVcm-1. In this regime, nonlinear phononics can transiently\nchange the average lattice structure, and with it the functionality of a\nmaterial. Here, we achieve an order-of-magnitude increase in field strength,\nand explore higher-order lattice nonlinearities. We drive up to five phonon\nharmonics of the A1 mode in LiNbO3. Phase-sensitive measurements of atomic\ntrajectories in this regime are used to experimentally reconstruct the\ninteratomic potential and to benchmark ab-initio calculations for this\nmaterial. Tomography of the Free Energy surface by high-order nonlinear\nphononics will impact many aspects of materials research, including the study\nof classical and quantum phase transitions.",
        "positive": "Enhancing $T_c$ in ferromagnetic semiconductors: We theoretically investigate disorder effects on the ferromagnetic transition\n('Curie') temperature $T_c$ in dilute III$_{1-x}$Mn$_x$V magnetic\nsemiconductors (e.g. Ga$_{1-x}$Mn$_x$As) where a small fraction ($x \\approx\n0.01-0.1$) of the cation atoms (e.g. Ga) are randomly replaced by the magnetic\ndopants (e.g. Mn), leading to long-range ferromagnetic ordering for $T<T_c$. We\nfind that $T_c$ is a complicated function of at least eight different\nparameters including carrier density, magnetic dopant density, and carrier mean\nfree path; nominally macroscopically similar samples could have substantially\ndifferent Curie temperatures. We provide simple physically appealing\nprescriptions for enhancing $T_c$ in diluted magnetic semiconductors, and\ndiscuss the magnetic phase diagram in the system parameter space."
    },
    {
        "anchor": "Study of the Electronic Structure in Oxides Using Absorption and\n  Resonant X-Ray Scattering: Resonant X-ray scattering (RXS) is a spectroscopy where both the power of\nsite selective diffraction and the power of local absorption spectroscopy\nregarding atomic species are combined. By virtue of the dependence on the core\nlevel state energy and the three dimensional electronic structure of the\nintermediate state, this technique is specially suited to study charge, orbital\nor spin orderings and associated crystal distortions. In the case of charge\nordering, we exploit the fact that atoms with closely related site symmetries\nbut with small charge differences exhibit resonances at slightly different\nenergies. The sensitivity of this effect allows for quantitative estimations of\nthe charge disproportion. Opposite to fluorescence or absorption measurements,\nthe power of diffraction relies on the capability of detecting differences that\nare smaller than the inverse lifetime of the core hole level. To account for\nthe uncertainty of the crystallographic structure and the fact that the charge\nordering must be disentangled from the associated atomic displacements, a\ncomplete methodology is proposed and applied to the low temperature phase of\nmagnetite. Relative sensitivity on spin, toroidal and orbital ordering is also\nshown and compared in different transition metal oxide compounds, like V2O3 and\nGaFeO3.",
        "positive": "Corrosion-resistant aluminum alloy design through machine learning\n  combined with high-throughput calculations: Efficiently designing lightweight alloys with combined high corrosion\nresistance and mechanical properties remains an enduring topic in materials\nengineering. To this end, machine learning (ML) coupled ab-initio calculations\nis proposed within this study. Due to the inadequate accuracy of conventional\nstress-strain ML models caused by corrosion factors, a novel reinforcement\nself-learning ML algorithm (accuracy R2 >0.92) is developed. Then, a strategy\nthat integrates ML models, calculated energetics and mechanical moduli is\nimplemented to optimize the Al alloys. Next, this Computation Designed\nCorrosion-Resistant Al alloy is fabricated that verified the simulation. The\nperformance (elongation reaches ~30%) is attributed to the H-captured Al-Sc-Cu\nphases (-1.44 eV H-1) and Cu-modified {\\eta}/{\\eta}' precipitation inside the\ngrain boundaries (GBs). The developed Al-Mg-Zn-Cu interatomic potential (energy\naccuracy 6.50 meV atom-1) proves the cracking resistance of the GB region\nenhanced by Cu-modification. Conceptually, our strategy is of practical\nimportance for designing new alloys exhibiting corrosion resistance and\nmechanical properties."
    },
    {
        "anchor": "Observation of linearly dispersive edge modes in a magnetic Weyl\n  semimetal Co3Sn2S2: The physical realization of Chern insulators is of fundamental and practical\ninterest, as they are predicted to host the quantum anomalous Hall effect\n(QAHE) and topologically protected chiral edge states which can carry\ndissipationless current. The realization of the QAHE state has however been\nchallenging because of the complex heterostructures and sub-Kelvin temperatures\nrequired. Time-reversal symmetry breaking Weyl semimetals, being essentially\nstacks of Chern insulators with inter-layer coupling, may provide a new\nplatform for the higher temperature realization of robust QAHE edge states. In\nthis work we present a combined scanning tunneling spectroscopy and theoretical\ninvestigation of a newly discovered magnetic Weyl semimetal, Co3Sn2S2. Using\nmodeling and numerical simulations we find that chiral edge states can be\nlocalized on partially exposed Kagome planes on the surface of a Weyl\nsemimetal. Correspondingly, our STM dI/dV maps on narrow kagome Co3Sn terraces\nshow linearly dispersing quantum well like states, which can be attributed to\nhybridized chiral edge modes. Our experiment and theory results suggest a new\nparadigm for studying chiral edge modes in time-reversal breaking Weyl\nsemimetals. More importantly, this work leads a practical route for realizing\nhigher temperature QAHE.",
        "positive": "Anomalous Polarization Reversal in Strained Thin Films of CuInP$_2$S$_6$: Strain-induced transitions of polarization reversal in thin films of a\nferrielectric CuInP$_2$S$_6$ (CIPS) with ideally-conductive electrodes is\nexplored using the Landau-Ginzburg-Devonshire (LGD) approach with an\neighth-order free energy expansion in polarization powers. Due to multiple\npotential wells, the height and position of which are temperature- and\nstrain-dependent, the energy profiles of CIPS can flatten in the vicinity of\nthe non-zero polarization states. This behavior differentiates these materials\nfrom classical ferroelectrics with the first or second order\nferroelectric-paraelectric phase transition, for which potential energy\nprofiles can be shallow or flat near the transition point only, corresponding\nto zero spontaneous polarization. Thereby we reveal an unusually strong effect\nof the mismatch strain on the out-of-plane polarization reversal, hysteresis\nloops shape, dielectric susceptibility, and piezoelectric response of CIPS\nfilms. In particular, by varying the sign of the mismatch strain and its\nmagnitude in a narrow range, quasi-static hysteresis-less paraelectric curves\ncan transform into double, triple, and other types of pinched and single\nhysteresis loops. The strain effect on the polarization reversal is opposite,\ni.e., \"anomalous\", in comparison with many other ferroelectric films in that\nthe out-of-plane remanent polarization and coercive field increases strongly\nfor tensile strains, meanwhile the polarization decreases or vanish for\ncompressive strains. We explain the effect by \"inverted\" signs of linear and\nnonlinear electrostriction coupling coefficients of CIPS and their strong\ntemperature dependence. For definite values of temperature and mismatch strain,\nthe low-frequency hysteresis loops of polarization may exhibit negative slope\nin the relatively narrow range of external field amplitude and frequency."
    },
    {
        "anchor": "Spin-dependent direct gap emission in tensile-strained Ge films on Si\n  substrates: The circular polarization of direct gap emission of Ge is studied in\noptically-excited tensile-strained Ge-on-Si heterostructures as a function of\ndoping and temperature. Owing to the spin-dependent optical selection rules,\nthe radiative recombinations involving strain-split light (cG-LH) and heavy\nhole (cG-HH) bands are unambiguously resolved. The fundamental cG-LH transition\nis found to have a low temperature circular polarization degree of about 85%\ndespite an off-resonance excitation of more than 300 meV. By photoluminescence\n(PL) measurements and tight binding calculations we show that this\nexceptionally high value is due to the peculiar energy dependence of the\noptically-induced electron spin population. Finally, our observation of the\ndirect gap doublet clarifies that the light hole contribution, previously\nconsidered to be negligible, can dominate the room temperature PL even at low\ntensile strain values of about 0.2%.",
        "positive": "Disorder-Induced First Order Transition and Curie Temperature Lowering\n  in Ferromagnatic Manganites: We study the effect that size disorder in the cations surrounding manganese\nions has on the magnetic properties of manganites. This disorder is mimic with\na proper distribution of spatially disordered Manganese energies. Both, the\nCurie temperature and the order of the transition are strongly affected by\ndisorder. For moderate disorder the Curie temperature decreases linearly with\nthe the variance of the distribution of the manganese site energies, and for a\ndisorder comparable to that present in real materials the transition becomes\nfirst order. Our results provide a theoretical framework to understand disorder\neffects on the magnetic behavior of manganites."
    },
    {
        "anchor": "Scattering-dependent transport of SrRuO3 films: From Weyl fermion\n  transport to hump-like Hall effect anomaly: Recent observation of quantum transport phenomena of Weyl fermions has\nbrought much attention to 4d ferromagnetic perovskite SrRuO3 as a magnetic Weyl\nsemimetal. Besides, the hump-like Hall effect anomaly, which might have a\ntopological origin, has also been reported for this material. Here, we show\nthat the emergence of such phenomena is governed by the degree of scattering\ndetermined by the defect density (Ru-deficiency- and/or interface-driven-defect\nscattering) and measurement temperature (phonon scattering), where the former\nis controlled by varying the growth conditions of the SrRuO3 films in molecular\nbeam epitaxy as well as the film thickness. The resulting electronic transport\nproperties can be classified into three categories: clean, intermediate, and\ndirty regimes. The transport of Weyl fermions emerges in the clean regime,\nwhereas that of topologically trivial conduction electrons in the ferromagnetic\nmetal state prevail in the intermediate and dirty regimes. In the clean and\nintermediate regimes, anomalous Hall resistivity obeys a scaling law\nincorporating the intrinsic Karplus-Luttinger (Berry phase) and extrinsic\nside-jump mechanisms. The hump-like Hall effect anomaly is observed only in the\ndirty regime, which is contrary to the scaling law between anomalous Hall\nresistivity and longitudinal resistivity. Hence, we conclude that this anomaly\nis not inherent to the material and does not have a topological origin. We also\nprovide defect- and temperature-dependent transport phase diagrams of\nstoichiometric SrRuO3 and Ru-deficient SrRu0.7O3 where the appearance of Weyl\nfermions and hump-like Hall effect anomaly are mapped. These diagrams may serve\nas a guideline for designing SrRu1-xO3-based spintronic and topological\nelectronic devices.",
        "positive": "Credit to Pioneering Work on Carbon Nanotubes: This letter gives a credit to a pioneering paper that is almost unknown to\nscientific community. On the basis of Transmission Electron Microscopy images\nand X-ray Ray Diffraction patterns of carbon multi-layer tubular crystals the\nauthors suggested a model of nanotube structure formation and hypothesis on\nvarious chirality of carbon nanotubes."
    },
    {
        "anchor": "Enhanced Spin Hall Ratio in Two-Dimensional III-V Semiconductors: Spin Hall effect plays a critical role in spintronics since it can convert\ncharge current to spin current. Using state-of-the-art ab initio calculations\nincluding quadrupole and spin-orbit coupling, the charge and spin transports\nhave been investigated in pristine and doped two-dimensional III-V\nsemiconductors. Valence bands induce a strong scattering which limits charge\nconductivity in the hole-doped system, where spin Hall conductivity is enhanced\nby the spin-orbit splitting, yielding an ultrahigh spin Hall ratio\n$\\xi\\approx0.9$ in GaAs monolayer at room temperature.",
        "positive": "Electronic Structures of SiC Nanoribbons: Electronic structures of SiC nanoribbons have been studied by spin-polarized\ndensity functional calculations. The armchair nanoribbons are nonmagnetic\nsemiconductor, while the zigzag nanoribbons are magnetic metal. The spin\npolarization in zigzag SiC nanoribbons is originated from the unpaired\nelectrons localized on the ribbon edges. Interestingly, the zigzag nanoribbons\nnarrower than $\\sim$4 nm present half-metallic behavior. Without the aid of\nexternal field or chemical modification, the metal-free half-metallicity\npredicted for narrow SiC zigzag nanoribbons opens a facile way for nanomaterial\nspintronics applications."
    },
    {
        "anchor": "Combined first-principles and EXAFS study of structural instability in\n  BaZrO3: Phonon spectrum of cubic barium zirconate is calculated from first principles\nusing the density functional theory. Unstable phonon mode with the $R_{25}$\nsymmetry in the phonon spectrum indicates an instability of the cubic structure\nwith respect to rotations of the oxygen octahedra. It is shown that the\nground-state structure of the crystal is $I4/mcm$. In order to find the\nmanifestations of the predicted instability, EXAFS measurements at the Ba\n$L_{\\rm III}$-edge are used to study the local structure of BaZrO$_3$ at 300 K.\nAn enhanced value of the Debye-Waller factor for the Ba-O atomic pair\n($\\sigma^2_1 \\sim 0.015$ {\\AA}$^2$) revealed in the experiment is associated\nwith the predicted structural instability. The average amplitude of the thermal\noctahedra rotation estimated from the measured $\\sigma^2_1$ value is $\\sim$4\ndegrees at 300 K. The closeness of the calculated energies of different\ndistorted phases resulting from the condensation of the $R_{25}$ mode suggests\na possible structural glass formation in BaZrO$_3$ when lowering temperature,\nwhich explains the cause of the discrepancy between the calculations and\nexperiment.",
        "positive": "Interpretable, calibrated neural networks for analysis and understanding\n  of inelastic neutron scattering data: Deep neural networks provide flexible frameworks for learning data\nrepresentations and functions relating data to other properties and are often\nclaimed to achieve 'super-human' performance in inferring relationships between\ninput data and desired property. In the context of inelastic neutron scattering\nexperiments, however, as in many other scientific scenarios, a number of issues\narise: (i) scarcity of labelled experimental data, (ii) lack of uncertainty\nquantification on results, and (iii) lack of interpretability of the deep\nneural networks. In this work we examine approaches to all three issues. We use\nsimulated data to train a deep neural network to distinguish between two\npossible magnetic exchange models of a half-doped manganite. We apply the\nrecently developed deterministic uncertainty quantification method to provide\nerror estimates for the classification, demonstrating in the process how\nimportant realistic representations of instrument resolution in the training\ndata are for reliable estimates on experimental data. Finally we use class\nactivation maps to determine which regions of the spectra are most important\nfor the final classification result reached by the network."
    },
    {
        "anchor": "Manifestly gauge independent formulations of the Z2 invariants: We use a \"monodromy\" argument to derive new expressions for the ${\\bm Z}_2$\ninvariants of topological insulators with time-reversal symmetry in 2 and 3\ndimensions. The derivations and the final expressions do not require any gauge\nchoice and the calculation of the invariants is based entirely on the\nprojectors onto the occupied states. Explicit numerical tests for tight-binding\nmodels with strongly broken inversion symmetry are presented in 2 and\n3-dimensions.",
        "positive": "Valence-selective local atomic structures on a YbInCu4 valence\n  transition material by x-ray fluorescence holography: An experimental technique of x-ray fluorescence holography for investigating\nvalence-selective local structures was established by employing the incident\nx-ray energy at a characteristic one near an x-ray absorption edge, and it was\nadopted to discriminate environments around Yb2+ and Yb3+ ions in a YbInCu4\nvalence transition material below and above the transition temperature of 42 K.\nThe reconstructed images of the neighboring atoms around Yb3+ show a fcc\nstructure as observed by diffraction experiments, whereas those around Yb2+\nhave curious cross (+) features, indicating a positional shift of the centered\nYb2+ ions from the fcc lattice point."
    },
    {
        "anchor": "Disturbance of spin equilibrium by current through the interface of\n  noncollinear ferromagnets: Boundary conditions are derived that determine the penetration of spin\ncurrent through an interface of two non-collinear ferromagnets with an\narbitrary angle between their magnetization vectors. We start from the\nwell-known transformation properties of an electron spin wave functions under\nthe rotation of a quantization axis. It allows directly find the connection\nbetween partial electric current densities for different spin subbands of the\nferromagnets. No spin scattering is assumed in the near interface region, so\nthat spin conservation takes place when electron intersects the boundary. The\ncontinuity conditions are found for partial chemical potential differences in\nthe situation. Spatial distribution of nonequilibrium electron magnetizations\nis calculated under the spin current flowing through a contact of two\nsemi-infinite ferromagnets. The distribution describes the spin accumulation\neffect by current and corresponding shift of the potential drop at the\ninterface. These effects appear strongly dependent on the relation between spin\ncontact resistances at the interface.",
        "positive": "Microstructure-based modeling of elastic functionally graded materials:\n  One dimensional case: Functionally graded materials (FGMs) are two-phase composites with\ncontinuously changing microstructure adapted to performance requirements.\nTraditionally, the overall behavior of FGMs has been determined using local\naveraging techniques or a given smooth variation of material properties.\nAlthough these models are computationally efficient, their validity and\naccuracy remain questionable, since a link with the underlying microstructure\n(including its randomness) is not clear. In this paper, we propose a modeling\nstrategy for the linear elastic analysis of FGMs systematically based on a\nrealistic microstructural model. The overall response of FGMs is addressed in\nthe framework of stochastic Hashin-Shtrikman variational principles. To allow\nfor the analysis of finite bodies, recently introduced discretization schemes\nbased on the Finite Element Method and the Boundary Element Method are employed\nto obtain statistics of local fields. Representative numerical examples are\npresented to compare the performance and accuracy of both schemes. To gain\ninsight into similarities and differences between these methods and to minimize\ntechnicalities, the analysis is performed in the one-dimensional setting."
    },
    {
        "anchor": "Tuning thermoelectric properties of Sb$_2$Te$_3$-AgSbTe$_2$\n  nanocomposite thin film -- synergy of band engineering and heat transport\n  modulation: The present study demonstrates a large enhancement in the Seebeck coefficient\nand ultralow thermal conductivity (TE) in Sb$_2$Te$_3$-AgSbTe$_2$ nanocomposite\nthin film. The addition of Ag leads to the in-situ formation of AgSbTe$_2$\nsecondary phase nanoaggregates in the Sb$_2$Te$_3$ matrix during the growth\nresulting in a large Seebeck coefficient and reduction of the thermal\nconductivity. A series of samples with different amounts of minor AgSbTe$_2$\nphases are prepared to optimize the TE performance of Sb$_2$Te$_3$ thin films.\nBased on the experimental and theoretical evidence, it is concluded that a\nsmall concentration of Ag promotes the band flattening and induces a sharp\nresonate-like state deep inside the valence band of Sb$_2$Te$_3$, concurrently\nmodifying the density of states (DOS) of the composite sample. In addition, the\nelectrical potential barrier introduced by the band offset between the host TE\nmatrix and the secondary phases promotes strong energy-dependent carrier\nscattering in the composite sample, which is also responsible for enhanced TE\nperformance. A contemporary approach based on scanning thermal microscopy is\nperformed to experimentally obtain thermal conductivity values of both the\nin-plane and cross-plane directions, showing a reduced in-plane thermal\nconductivity value by ~ 58% upon incorporating the AgSbTe$_2$ phase in the\nSb$_2$Te$_3$ matrix. Benefitting from the synergistic manipulation of\nelectrical and thermal transport, a large ZT value of 2.2 is achieved at 375 K.\nThe present study indicates the importance of a combined effect of band\nstructure modification and energy-dependent charge carrier scattering along\nwith reduced thermal conductivity for enhancing TE properties.",
        "positive": "The electrocaloric response in Lanthanum-modified lead zirconate\n  titanate ceramic: Over the past decades, there has been significant interest in new cooling\ntechnology based on the electrocaloric effect. The large electrocaloric effect\nobserved in polymeric and inorganic ferroelectric materials made possible\ndevelopment of dielectric cooling devices of a new generation. We report a\nsignificant impact of annealing on the electrocaloric effect observed in\n12/65/35 PLZT bulk ceramics. The electrocaloric data were obtained by direct\nmeasurements. Electrocaloric results confirm the existence of the significant\nelectrocaloric response in this relaxor ferroelectric PLZT composition\nexceeding previously obtained electrocaloric values in perovskite relaxor\nferroelectrics such as PMN-PT and x/65/35 PLZT ceramics."
    },
    {
        "anchor": "Manipulating Current-Induced Magnetization Switching: We summarize our recent findings on how current-driven magnetization\nswitching and magnetoresistance in nanofabricated magnetic multilayers are\naffected by varying the spin-scattering properties of the non-magnetic spacers,\nthe relative orientations of the magnetic layers, and spin-dependent scattering\nproperties of the interfaces and the bulk of the magnetic layers. We show how\nour data are explained in terms of current-dependent effective magnetic\ntemperature.",
        "positive": "Halogenated MXenes with Electrochemically Active Terminals for High\n  Performance Zinc Ion Batteries: The class of two-dimensional metal carbides and nitrides known as MXenes\noffer a distinct manner of property tailoring for a wide range of applications.\nThe ability to tune the surface chemistry for expanding the property space of\nMXenes is thus an important topic, although experimental exploration of new\nsurface terminals remains a challenge. Here, we synthesized Ti3C2 MXene with\nunitary, binary and ternary halogen terminals, e.g. -Cl, -Br, -I, -BrI and\n-ClBrI, to investigate the effect of surface chemistry on the properties of\nMXenes. The electrochemical activity of Br and I element result in the\nextraordinary electrochemical performance of the MXenes as cathodes for aqueous\nzinc ion batteries. The -Br and -I containing MXenes, e.g. Ti3C2Br2 and\nTi3C2I2, exhibit distinct discharge platforms with considerable capacities of\n97.6 mAh g-1 and 135 mAh g-1. Ti3C2(BrI) and Ti3C2(ClBrI) exhibit dual\ndischarge platforms with capacities of 117.2 mAh g-1 and 106.7 mAh g-1. In\ncontrast, the previously discovered MXenes Ti3C2Cl2 and Ti3C2(OF) exhibit no\ndischarge platforms, and only ~50% of capacities and energy densities of\nTi3C2Br2. These results emphasize the effectiveness of the Lewis-acidic-melt\netching route for tuning the surface chemistry of MXenes, and also show promise\nfor expanding the MXene family towards various applications."
    },
    {
        "anchor": "Structure and energetics of carbon-related defects in SiC\n  (0001)/SiO$_{\\rm 2}$ systems revealed by first-principles calculations:\n  Defects in SiC, SiO$_{\\rm 2}$, and just at their interface: We report first-principles calculations that reveal the atomic forms,\nstability, and energy levels of carbon-related defects in SiC (0001)/SiO$_{\\rm\n2}$ systems. We clarify the stable position (SiC side, SiO$_{\\rm 2}$ side, or\njust at the SiC/SiO$_{\\rm 2}$ interface) of defects depending on the oxidation\nenvironment. Under an O-rich condition, the di-carbon antisite ((C$_{\\rm\n2}$)$_{\\rm Si}$) in the SiC side is stable and critical for $n$-channel\nMOSFETs, whereas the di-carbon defect (Si-C-C-Si) at the interface becomes\ncritical under an O-poor condition. Our results suggest that the oxidation of\nSiC under a high-temperature O-poor condition is favorable in reducing the\ndefects, in consistent with recent experimental reports.",
        "positive": "Chiral spin-wave velocities induced by all-garnet interfacial\n  Dzyaloshinskii-Moriya interaction in ultrathin yttrium iron garnet films: Spin waves can probe the Dzyaloshinskii-Moriya interaction (DMI) which gives\nrise to topological spin textures, such as skyrmions. However, the DMI has not\nyet been reported in yttrium iron garnet (YIG) with arguably the lowest damping\nfor spin waves. In this work, we experimentally evidence the interfacial DMI in\na 7~nm-thick YIG film by measuring the nonreciprocal spin wave propagation in\nterms of frequency, amplitude and most importantly group velocities using all\nelectrical spin-wave spectroscopy. The velocities of propagating spin waves\nshow chirality among three vectors, i.e. the film normal direction, applied\nfield and spin-wave wavevector. By measuring the asymmetric group velocities,\nwe extract a DMI constant of 16~$\\mu$J/m$^{2}$ which we independently confirm\nby Brillouin light scattering. Thickness-dependent measurements reveal that the\nDMI originates from the oxide interface between the YIG and garnet substrate.\nThe interfacial DMI discovered in the ultrathin YIG films is of key importance\nfor functional chiral magnonics as ultra-low spin-wave damping can be achieved."
    },
    {
        "anchor": "Role of charged defects on the electrical and electro-mechanical\n  properties of rhombohedral Pb(Zr,Ti)O3 with oxygen octahedra tilts: Oxygen octahedra tilting is a common structural phenomenon in perovskites and\nhas been subject of intensive studies, particularly in rhombohedral Pb(Zr,Ti)O3\n(PZT). Early reports suggest that the tilted octahedra may strongly affect the\ndomain switching behavior, dielectric and piezoelectric properties of PZT\nceramics. In a way similar to that proposed for tilts, however, charged\ndefects, associated with oxygen vacancies, may also inhibit the motion of the\ndomain walls, resulting macroscopically in pinched hysteresis loops and reduced\npiezoelectric response. Here, we revisit the early studies on rhombohedral PZT\nceramics with tilted octahedra by considering a possible role of both tilts and\ncharged defects on domain-wall motion. We show that the observed pinched\nhysteresis loops are likely associated with the presence of defect complexes\ncontaining charged oxygen vacancies, and not tilts as suggested in some cases.\nRegardless of the presence or absence of long-range ordered tilts in\nrhombohedral PZT, the effect of charged defects is also prominent in weak-field\npermittivity and piezoelectric properties, particularly at sub-Hz driving\nconditions where the conductivity, related to the motion of oxygen vacancies,\ngives rise to strong frequency dispersion.",
        "positive": "First-principles prediction of high Curie temperature for ferromagnetic\n  bcc-Co and bcc-FeCo alloys and its relevance to tunneling magnetoresistance: We determine from first-principles the Curie temperature Tc for bulk Co in\nthe hcp, fcc, bcc, and tetragonalized bct phases, for FeCo alloys, and for bcc\nand bct Fe. For bcc-Co, Tc=1420 K is predicted. This would be the highest Curie\ntemperature among the Co phases, suggesting that bcc-Co/MgO/bcc-Co tunnel\njunctions offer high magnetoresistance ratios even at room temperature. The\nCurie temperatures are calculated by mapping ab initio results to a Heisenberg\nmodel, which is solved by a Monte Carlo method."
    },
    {
        "anchor": "Size Dependence and Convergence of the Retrieval Parameters of\n  Metamaterials: We study the dependence of the retrieval parameters, such as the electric\npermittivity, the magnetic permeability and the index of refraction, $n$, on\nthe size of the unit cell of a periodic metamaterial. The convergence of the\nretrieved parameters on the number of the unit cells is also examined. We have\nconcentrated our studies on the so-called fishnet structure, which is the most\npromising design to obtain negative $n$ at optical wavelengths. We find that as\nthe size of the unit cell decreases, the magnitude of the retrieved effective\nparameters increases. The convergence of the effective parameters of the\nfishnet as the number of the unit cells increases is demonstrated but found to\nbe slower than for regular split ring resonators and wires structures. This is\ndue to a much stronger coupling between the different unit cells in the fishnet\nstructure.",
        "positive": "Crystal Truncation Rods from Miscut Surfaces with Alternating\n  Terminations: Miscut surfaces of layered crystals can exhibit a stair-like sequence of\nterraces having periodic variation in their atomic structure. For hexagonal\nclose-packed and related crystal structures with an\n{\\alpha}{\\beta}{\\alpha}{\\beta} stacking sequence, there have been long-standing\nquestions regarding how the differences in adatom attachment kinetics at the\nsteps separating the terraces affect the fractional coverage of {\\alpha} vs.\n{\\beta} termination during crystal growth. To demonstrate how surface X-ray\nscattering can help address these questions, we develop a general theory for\nthe intensity distributions along crystal truncation rods (CTRs) for miscut\nsurfaces with a combination of two terminations. We consider\nhalf-unit-cell-height steps, and variation of the coverages of the terraces\nabove each step. Example calculations are presented for the GaN (0001) surface\nwith various reconstructions. These show which CTR positions are most sensitive\nto the fractional coverage of the two terminations. We compare the CTR profiles\nfor exactly oriented surfaces to those for vicinal surfaces having a small\nmiscut angle, and investigate the circumstances under which the CTR profile for\nan exactly oriented surface is equal to the sum of the intensities of the\ncorresponding family of CTRs for a miscut surface."
    },
    {
        "anchor": "PrVO$_4$ under High Pressure: Effects on Structural, Optical and\n  Electrical Properties: In pursue of a systematic characterization of rare-earth vanadates under\ncompression, in this work we present a multifaceted study of the phase behavior\nof zircon-type orthovanadate PrVO$_4$ under high pressure conditions, up until\n24 GPa. We have found that PrVO$_4$ undergoes a zircon to monazite transition\nat around 6 GPa, confirming previous results found by Raman experiments. A\nsecond transition takes place above 14 GPa, to a BaWO$_4$-I--type structure.\nThe zircon to monazite structural sequence is an irreversible first-order\ntransition, accompanied by a volume collapse of about 9.6%. Monazite phase is\nthus a metastable polymorph of PrVO$_4$. The monazite-BaWO$_4$-II transition is\nfound to be reversible instead and occurs with a similar volume change. Here we\nreport and discuss the axial and bulk compressibility of all phases. We also\ncompare our results with those for other rare-earth orthovanadates. Finally, by\nmeans of optical-absorption experiments and resistivity measurements we\ndetermined the effect of pressure on the electronic properties of PrVO$_4$. We\nfound that the zircon-monazite transition produces a collapse of the band gap\nand an abrupt decrease of the resistivity. The physical reasons for this\nbehavior are discussed. Density-functional-theory simulations support our\nconclusions.",
        "positive": "Wrinkling hierarchy in constrained thin sheets from suspended graphene\n  to curtains: We show that thin sheets under boundary confinement spontaneously generate a\nuniversal self-similar hierarchy of wrinkles. From simple geometry arguments\nand energy scalings, we develop a formalism based on wrinklons, the transition\nzone in the merging of two wrinkles, as building-blocks of the global pattern.\nContrary to the case of crumple paper where elastic energy is focused, this\ntransition is described as smooth in agreement with a recent numerical work.\nThis formalism is validated from hundreds of nm for graphene sheets to meters\nfor ordinary curtains, which shows the universality of our description. We\nfinally describe the effect of an external tension to the distribution of the\nwrinkles."
    },
    {
        "anchor": "Stable solid molecular hydrogen above 900K from a machine-learned\n  potential trained with diffusion Quantum Monte Carlo: We survey the phase diagram of high-pressure molecular hydrogen with path\nintegral molecular dynamics using a machine-learned interatomic potential\ntrained with Quantum Monte Carlo forces and energies. Besides the HCP and\nC2/c-24 phases, we find two new stable phases both with molecular centers in\nthe Fmmm-4 structure, separated by a molecular orientation transition with\ntemperature. The high temperature isotropic Fmmm-4 phase has a reentrant\nmelting line with a maximum at higher temperature (1450K at 150GPa) than\npreviously estimated and crosses the liquid-liquid transition line around 1200K\nand 200GPa.",
        "positive": "Morphological instability, evolution, and scaling in strained epitaxial\n  films: An amplitude equation analysis of the phase field crystal model: Morphological properties of strained epitaxial films are examined through a\nmesoscopic approach developed to incorporate both the film crystalline\nstructure and standard continuum theory. Film surface profiles and properties,\nsuch as surface energy, liquid-solid miscibility gap and interface thickness,\nare determined as a function of misfit strains and film elastic modulus. We\nanalyze the stress-driven instability of film surface morphology that leads to\nthe formation of strained islands. We find a universal scaling relationship\nbetween the island size and misfit strain which shows a crossover from the\nwell-known continuum elasticity result at the weak strain to a behavior\ngoverned by a \"perfect\" lattice relaxation condition. The strain at which the\ncrossover occurs is shown to be a function of liquid-solid interfacial\nthickness, and an asymmetry between tensile and compressive strains is\nobserved. The film instability is found to be accompanied by mode coupling of\nthe complex amplitudes of the surface morphological profile, a factor\nassociated with the crystalline nature of the strained film but absent in\nconventional continuum theory."
    },
    {
        "anchor": "Evidence of Gas Phase Nucleation of Nano Diamond in Microwave Plasma\n  Assisted Chemical Vapor Deposition: The mechanism of ballas like nano crystalline diamond formation (NCD) still\nremains elusive, and this work attempts to analyze its formation in the\nframework of activation energy ($E_\\text{a}$) of NCD films grown from\nH$_\\text{2}$/CH$_\\text{4}$ plasma in a 2.45 GHz chemical vapor deposition\nsystem. The $E_\\text{a}$ is calculated using the Arrhenius equation\ncorresponding to the thickness growth rate while using substrate temperature\n($\\sim1000-1300$ K) in all the calculations. While the calculated values match\nwith the $E_\\text{a}$ for nano diamond formation throughout the literature,\nthese values of $\\sim$10 kcal/mol are lower compared to $\\sim$15 -- 25 kcal/mol\nfor standard single crystal diamond (SCD) formation, concluding thus far, that\nthe energetics and processes involved are different. In this work, To further\ninvestigate this, the substrate preparation and sample collection method are\nmodified while keeping the growth parameters constant. Unseeded Si substrates\nare physically separated from the plasma discharge by a molybdenum plate with a\npinhole drilled in it. Small quantities of a sample substance are collected on\nthe substrates. The sample is characterized by electron microscopy and Raman\nspectroscopy confirming it to be nano diamond, thus, suggesting that nano\ndiamond self nucleates in the plasma and flows to the substrate which acts as a\nmere collection plate. It is hypothesized then, if nano diamond nucleates in\ngas phase, gas temperature has to be used in the Arrhenius analysis. The\n$E_\\text{a}$ values for all the nano diamond films are re-calculated using the\nsimulated gas temperature ($\\sim1500-2000$ K) obtained from a simple\nH$_\\text{2}$/CH$_\\text{4}$ plasma model, giving values within the range\ncharacteristic to SCD formation. A unified growth mechanism for NCD and SCD is\nproposed concluding that the limiting reactions for NCD and SCD formation are\nthe same.",
        "positive": "A Microscopic Model of Ferroelectricity in Stress-free PbTiO3 Ultrathin\n  Films: The ground-state polarization of PbTiO3 thin films is studied using a\nmicroscopic effective Hamiltonian with parameters obtained from\nfirst-principles calculations. Under short-circuit electrical boundary\nconditions, (001) films with thickness as low as three unit cells are found to\nhave a perpendicularly polarized ferroelectric ground state with significant\nenhancement of the polarization at the surface."
    },
    {
        "anchor": "Towards Obtaining 2D and 3D and 1D PtPN with Pentagonal Pattern: We apply an alloying strategy to single-layer PtN$_2$ and PtP$_2$, aiming to\nobtain a single-layer Pt-P-N alloy with a relatively low formation energy with\nreference to its bulk structure. We perform structure search based on a\ncluster-expansion method and predict single-layer and bulk PtPN consisting of\npentagonal networks. The formation energy of single-layer PtPN is significantly\nlower in comparison with that of single-layer PtP$_2$. The predicted bulk\nstructure of PtPN adopts a structure that is similar to the pyrite structure.\nWe also find that single-layer pentagonal PtPN, unlike PtN$_2$ and PtP$_2$,\nexhibits a sizable, direct PBE band gap of 0.84 eV. Furthermore, the band gap\nof single-layer pentagonal PtPN calculated with the hybrid density functional\ntheory is 1.60 eV, which is within visible light spectrum and promising for\noptoelectronics applications. In addition to predicting PtPN in the 2D and 3D\nforms, we study the flexural rigidity and electronic structure of PtPN in the\nnanotube form. We find that single-layer PtPN has similar flexural rigidity to\nthat of single-layer carbon and boron nitride nanosheets and that the band gaps\nof PtPN nanotubes depend on their radii. Our work shed light on obtaining an\nisolated 2D planar, pentagonal PtPN nanosheet from its 3D counterpart and on\nobtaining 1D nanotubes with tunable bandgaps.",
        "positive": "Multiferroic behavior in the new double-perovskite Lu$_2$MnCoO$_6$: We present a new member of the multiferroic oxides, Lu$_2$MnCoO$_6$, which we\nhave investigated using X-ray diffraction, neutron diffraction, specific heat,\nmagnetization, electric polarization, and dielectric constant measurements.\nThis material possesses an electric polarization strongly coupled to a net\nmagnetization below 35 K, despite the antiferromagnetic ordering of the $S =\n3/2$ Mn$^{4+}$ and Co$^{2+}$ spins in an $\\uparrow \\uparrow \\downarrow\n\\downarrow$ configuration along the c-direction. We discuss the magnetic order\nin terms of a condensation of domain boundaries between $\\uparrow \\uparrow$ and\n$\\downarrow \\downarrow$ ferromagnetic domains, with each domain boundary\nproducing a net electric polarization due to spatial inversion symmetry\nbreaking. In an applied magnetic field the domain boundaries slide, controlling\nthe size of the net magnetization, electric polarization, and magnetoelectric\ncoupling."
    },
    {
        "anchor": "$\\textit{Ab initio}$ evidence for nonthermal characteristics in\n  ultrafast laser melting: Laser melting of semiconductors has been observed for almost 40 years;\nsurprisingly, it is not well understood where most theoretical simulations show\na laser-induced thermal process. $\\textit{Ab initio}$ nonadiabatic simulations\nbased on real-time time-dependent density functional theory reveal intrinsic\nnonthermal melting of silicon, at a temperature far below the thermal melting\ntemperature of 1680 K. Both excitation threshold and time evolution of\ndiffraction intensity agree well with experiment. Nonthermal melting is\nattributed to excitation-induced drastic changes in bonding electron density,\nand the subsequent decrease in the melting barrier, rather than lattice heating\nas previously assumed in the two-temperature models.",
        "positive": "The Scaled-Charge Additive Force Field for Amino Acid Based Ionic\n  Liquids: Abstract. Ionic liquids (ILs) constitute an emerging field of research. New\nILs are continuously introduced involving more and more organic and inorganic\nions. Amino acid based ILs (AAILs) represent a specific interest due to their\nevolutional connection to proteins. We report a new non- polarizable force\nfield (FF) for the eight AAILs comprising 1-ethyl-3-methylimidazolium cation\nand amino acid anions. The anions were obtained via deprotonation of carboxyl\ngroup. Specific cation-anion non-covalent interactions have been taken into\naccount by computing electrostatic potential for ion pairs, in contrast to\nisolated ions. The van der Waals interactions have been transferred from the\nCHARMM36 FF with minor modifications. Therefore, compatibility between our\nparameters and CHARMM36 parameters is preserved. Our FF can be easily\nimplemented using a variety of popular molecular dynamics programs. It will\nfind broad applications in computational investigation of ILs."
    },
    {
        "anchor": "Non-invasive control of excitons in two-dimensional materials: We investigate how external screening shapes excitons in two-dimensional (2d)\nsemiconductors embedded in laterally structured dielectric environments. An\natomic scale view of these elementary excitations is developed using models\nwhich apply to a variety of materials including transition metal\ndichalcogenides (TMDCs). We find that structured dielectrics imprint a peculiar\npotential energy landscape on excitons in these systems: While the ground-state\nexciton is least influenced, higher excitations are attracted towards regions\nwith high dielectric constant of the environment. This landscape is \"inverted\"\nin the sense that low energy excitons are less strongly affected than their\nhigher energy counterparts. Corresponding energy variations emerge on length\nscales of the order of a few unit cells. This opens the prospect of trapping\nand guiding of higher excitons by means of tailor-made dielectric substrates on\nultimately small spatial scales.",
        "positive": "Impact of gamma' particle coarsening on the critical resolved shear\n  stress of nickel-base superalloys with low aluminium and/or titanium content: In Ni-base superalloys with low Al and/or Ti content the precipitation and\nsubsequent coarsening of gamma' particles at intermediate temperatures\ncontribute to the degradation of the mechanical properties of the alloy. In the\npresent paper the coarsening process is modelled and the change of the critical\nresolved shear stress of the alloy due to coarsening of the gamma' particles is\ncalculated by means of statistical analysis of the depinning of a single\ngliding edge dislocation. It is found that the contribution of gamma' hardening\nto the critical resolved shear stress at 973 K reduces to more than half of its\noriginal value in less than one year."
    },
    {
        "anchor": "Predicted Novel Hydrogen Hydrate Structures under Pressure from First\n  Principles: Gas hydrates are systems of prime importance. In particular, hydrogen\nhydrates are potential materials of icy satellites and comets, and may be used\nfor hydrogen storage. We explore the H2O-H2 system at pressures in the range\n0-100 GPa with ab initio variable-composition evolutionary simulations.\nAccording to our calculation and previous experiments, the H2O-H2 system\nundergoes a series of transformations with pressure, and adopts the known\nopen-network clathrate structures (sII, C0), dense \"filled ice\" structures (C1,\nC2) and two novel hydrate phases. One of these is based on the hexagonal ice\nframework and has the same H2O:H2 ratio (2:1) as the C0 phase at low pressures\nand similar enthalpy (we name this phase Ih-C0). The other newly predicted\nhydrate phase has a 1:2 H2O:H2 ratio and structure based on cubic ice. This\nphase (which we name C3) is predicted to be thermodynamically stable above 38\nGPa when including van der Waals interactions and zero-point vibrational\nenergy, and explains previously mysterious experimental X-ray diffraction and\nRaman measurements. This is the hydrogen-richest hydrate and this phase has a\nremarkable gravimetric density (18 wt.%) of easily extractable hydrogen.",
        "positive": "Quantum Mechanical Modeling of Nanoscale Light Emitting Diodes: Understanding of the electroluminescence (EL) mechanism in optoelectronic\ndevices is important for further optimization of their efficiency and\neffectiveness. Here, a quantum mechanical approach is formulated for modeling\nEL processes in nanoscale light emitting diodes (LED). Based on nonequilibrium\nGreen's function quantum transport equations, interactions with electromagnetic\nvacuum environment is included to describe electrically driven light emission\nin the devices. Numerical studies of a silicon nanowire LED device are\npresented. EL spectra of the nanowire device under different bias voltages are\nsimulated and, more importantly, propagation and polarization of emitted photon\ncan be determined using the current approach."
    },
    {
        "anchor": "Model-based quantitative methods to predict irradiation-induced swelling\n  in alloys: Predicting volume swelling of structural materials in nuclear reactors under\nhigh-dose neutron irradiations based on existing low-dose experiments or\nirradiation data with high-dose-rate energetic particles has been a\nlong-standing challenge for safety evaluation and rapidly screening\nirradiation-resistant materials in nuclear energy systems. Here, we build an\nAdditional Defect Absorption Model that describes the irradiation-induced\nswelling effects produced by energetic electrons, heavy-ions, and neutrons by\nconsidering additional defect sinks inherent in the irradiation process. Based\non this model, we establish quantitative methods to predict high-dose swelling\nfrom low-dose behavior and obtain the equivalent irradiation dose for different\nenergetic particles when the dose rates differ by several orders of magnitude.\nFurthermore, we propose a universal parameter to characterize the swelling\nresistance of various alloys and predict their radiation tolerances under\ndifferent radiation conditions. This work provides quantitative prediction\nmethods for evaluating irradiation-induced swelling effects of structural\nmaterials, which is critical to the safety and material development for\nadvanced nuclear reactors.",
        "positive": "Quantum anomalous Hall effect in two dimensional Janus Mn2Cl3Br3 with\n  large magnetic anisotropy energy: The quantum anomalous Hall (QAH) effect have been experimentally observed in\nmagnetically-doped topological insulators. However, the QAH effect only at\nextremely low temperatures due to the weak magnetic coupling, small band gap\nand low carrier mobility. Here, based on first-principles density functional\ntheory, we predict that the Janus Mn2Cl3Br3 is high Curie temperature\nferromagnet that host the QAH phase. Furthermore, we find that it is a Dirac\nhalf-metal characterized by a Dirac cone in one spin channel with carrier\nmobilities comparable to freestanding germanene and an large band gap in other\nspin channel. Simultaneously, when the spin-orbital coupling interaction is\nconsidered, the Janus Mn2Cl3Br3 exhibit lager magnetic anisotropic energy of\n11.89 meV/cell and a nontrivial band gap. More interestingly, both the Chern\nnumber sign and the chiral edge current are tuned by changing the direction of\nmagnetization. Our finding would suggest the possibility of not only realized\nthe QAH effect but also designed the flow direction of the edge current."
    },
    {
        "anchor": "Elastic Properties of Graphyne-based Nanotubes: Graphyne nanotubes (GNTs) are nanostructures obtained from rolled up graphyne\nsheets, in the same way carbon nanotubes (CNTs) are obtained from graphene\nones. Graphynes are 2D carbon-allotropes composed of atoms in sp and sp2\nhybridized states. Similarly to conventional CNTs, GNTs can present different\nchiralities and electronic properties. Because of the acetylenic groups (triple\nbonds), GNTs exhibit large sidewall pores that influence their mechanical\nproperties. In this work, we studied the mechanical response of GNTs under\ntensile stress using fully atomistic molecular dynamics simulations and density\nfunctional theory (DFT) calculations. Our results show that GNTs mechanical\nfailure (fracture) occurs at larger strain values in comparison to\ncorresponding CNTs, but paradoxically with smaller ultimate strength and\nYoung's modulus values. This is a consequence of the combined effects of the\nexistence of triple bonds and increased porosity/flexibility due to the\npresence of acetylenic groups.",
        "positive": "Interfacial strain defines the self-organization of epitaxial MoO2\n  flakes and porous films on sapphire: experiments and modelling: The epitaxy of MoO2 on c_plane sapphire substrates is examined. A theoretical\napproach, based on density functional theory calculations of the strain energy,\nallowed to predict the preferred layer/substrate epitaxial relationships. To\ntest the results of these calculations, MoO2/(001) Al2O3 heterostructures were\ngrown using the chemically_driven isothermal close space vapour transport\ntechnique. At the early stages of the growth, two kinds of morphologies were\nobtained, using the same growth parameters: lying and standing flakes. The\ncomposition and morphology, as well as the layer/substrate epitaxial\nrelationships were determined for both kind of morphologies. Experimental\nepitaxial relationships coincide with those predicted by DFT calculation as the\nmost favourable ones in terms of strain energy. For thicker films, the standing\nflakes evolve to form an epitaxial porous layer composed by coalesced epitaxial\nflakes. The interfacial strain between the sapphire substrate and MoO2 enables\na self_organization from nanometer to micron scales between separated or\ncoalesced flakes, depending on deposition condition."
    },
    {
        "anchor": "Disorder-induced melting of the charge order in thin films of\n  Pr0.5Ca0.5MnO3: We have studied the magnetic-field-induced melting of the charge order in\nthin films of Pr0.5Ca0.5MnO3 (PCMO) films on SrTiO3 (STO) by X-ray diffraction,\nmagnetization and transport measurement. At small thickness (25 nm) the films\nare under tensile strain and the low-temperature melting fields are of the\norder of 20 T or more, comparable to the bulk value. With increasing film\nthickness the strain relaxes, which leads to a strong decrease of the melting\nfields. For a film of 150 nm, with in-plane and out-of-plane lattice parameters\ncloser to the bulk value, the melting field has reduced to 4 T at 50 K, with a\nstrong increase in the hysteretic behavior and also an increasing fraction of\nferromagnetic material. Strain relaxation by growth on a template of\nYBa2Cu3O(7-delta) or by post-annealing yields similar results with an even\nstronger reduction of the melting field. Apparently, strained films behave\nbulk-like. Relaxation leads to increasing suppression of the CO state,\npresumably due to atomic scale disorder produced by the relaxation process.",
        "positive": "Topological semimetal phases in a family of monolayer X3YZ6 (X=Nb,Ta,\n  Y=Si,Ge,Sn, Z=S,Se,Te) with abundant nodal lines and nodes: The electronic and topological properties of single-layer X3YZ6 (X=Nb,Ta,\nY=Si,Ge,Sn, Z=S,Se,Te) materials have been studied with the aid of first\nprinciples calculations. This kind of materials belong to topological\nsemimetals (TMs) with abundant nodal lines and nodes. Considering their similar\nproperties, we focus on the analysis of Ta3SnTe6 and Ta3SiSe6. The present of\nspin-orbit coupling (SOC) leads to the transition from type-I nodal lines to\nDirac points as well as the disappear of type-II Dirac points. The\nthree-dimensional (3D) band diagrams reproduce vividly the characteristics of\nnodes and nodal lines. The appearance of the flat bands in (110) edge states\nfurther confirm their nontrivial topological properties. We also explore the\nrelationship among different nodal lines (nodes), crystal symmetry and SOC. The\ntype-I nodal lines are protected by Mz and My symmetry in the absent of SOC.\nSymmetry breaking leads to band splitting even in the presence of SOC. The\nsingle-layer X3YZ6 can be used as candidates for two-dimensional (2D) TMs and\nprovide a platform for further study of interesting physical phenomena."
    },
    {
        "anchor": "Orientation Dependence of the Intrinsic Anomalous Hall Effect in hcp\n  Cobalt: We carry out first-principles calculations of the dependence of the intrinsic\nanomalous Hall conductivity of hcp Co on the magnetization direction. The Hall\nconductivity decreases smoothly from 481 S/cm to 116 S/cm as the magnetization\nis tilted from the c-axis to the ab-plane. This factor-of-four reduction\ncompares well with measurements on single crystals, while the angular average\nof 226 S/cm is in excellent agreement with the value of 205 S/cm measured in\npolycrystalline films. The strong anisotropy of the anomalous Hall conductivity\nis a consequence of spin-orbit induced changes in the electron states near the\nFermi level as the magnetization is rotated.",
        "positive": "Theory of electric, magnetic, and toroidal polarizations in crystalline\n  solids with applications to hexagonal lonsdaleite and cubic diamond: Multipolar order in bulk crystalline solids is characterized by multipole\ndensities -- denoted as polarizations in this work -- that cannot be cleanly\ndefined using the concepts of classical electromagnetism. Here we use group\ntheory to overcome this difficulty and present a systematic study of electric,\nmagnetic and toroidal multipolar order in crystalline solids. Based on our\nsymmetry analysis, we identify five categories of polarized matter, each of\nwhich is characterized by distinct features in the electronic band structure.\nFor example, Rashba spin splitting in electropolar bulk materials like wurtzite\nrepresents the electric dipolarization in these materials. We also develop a\ngeneral formalism of indicators for individual multipole densities that provide\na physical interpretation and quantification of multipolar order. Our work\nclarifies the relation between patterns of localized multipoles and macroscopic\nmultipole densities they give rise to. To illustrate the general theory, we\ndiscuss its application to polarized variants of hexagonal lonsdaleite and\ncubic diamond structures. Our work provides a general framework for classifying\nand expanding current understanding of multipolar order in complex materials."
    },
    {
        "anchor": "Anomalous thermal expansion in one-dimensional transition-metal\n  cyanides: Behavior of the trimetallic cyanide\n  Cu$_{1/3}$Ag$_{1/3}$Au$_{1/3}$CN: The structural dynamics of a 1D mixed-metal cyanide,\nCu$_{1/3}$Ag$_{1/3}$Au$_{1/3}$CN, with intriguing thermal properties is\nexplored. All the current known related compounds with straight-chain\nstructures, such as CuCN, AgCN, AuCN and M$_x$M'$_{1-x}$CN (M, M' = Cu, Ag,\nAu), exhibit 1D negative thermal expansion (NTE) along the chains and positive\nthermal expansion (PTE) perpendicular to them. Cu$_{1/3}$Ag$_{1/3}$Au$_{1/3}$CN\nexhibits similar PTE perpendicular to the chains, however PTE, rather than NTE,\nis also observed along the chains. In order to understand the origin of this\nunexpected behavior, inelastic neutron scattering (INS) measurements were\ncarried out, underpinned by DFT calculations. Synchrotron-based PDF analysis\nand 13C SSNMR measurements were also performed to build an input structural\nmodel for the lattice dynamical study. The results indicate that transverse\nmotions of the metal ions are responsible for the PTE perpendicular to the\nchains, as is the case for the related group 11 cyanides. However NTE along the\nchain due to the tension effect of these transverse motions is not observed.\nFor this system, DFT-based phonon calculations predict small PTE along the\nchain due to low-energy chain-slipping modes induced by a bond-rotation effect\non the weak metallophilic bonds. However the observed PTE is greater than that\npredicted with the straight-chain model. Small bends in the chain to\naccommodate truly co-planar metals provide an alternative explanation for\nthermal behavior. These would mitigate the tension effect induced by the\ntransverse motions of the metals and, as temperature increases and the chains\nmove further apart, a straightening could occur resulting in the observed PTE.\nThis hypothesis is further supported by unusual evolution in the phonon\nspectra, which suggest small changes in local symmetry with temperature.",
        "positive": "Calcium-Decorated Graphene-Based Nanostructures for Hydrogen Storage: We report a first-principles study of hydrogen storage media consisting of\ncalcium atoms and graphene-based nanostructures. We find that Ca atoms prefer\nto be individually adsorbed on the zigzag edge of graphene with a Ca-Ca\ndistance of 10 A without clustering of the Ca atoms, and up to six H2 molecules\ncan bind to a Ca atom with a binding energy of ~0.2 eV/H2. A Ca-decorated\nzigzag graphene nanoribbon (ZGNR) can reach the gravimetric capacity of ~5 wt %\nhydrogen. We also consider various edge geometries of the graphene for Ca\ndispersion."
    },
    {
        "anchor": "Room-temperature correlated states in twisted bilayer MoS$_2$: Moir\\'e superlattices have emerged as an exciting condensed-matter quantum\nsimulator for exploring the exotic physics of strong electronic correlations.\nNotable progress has been witnessed, but such correlated states are achievable\nusually at low temperatures. Here, we report the transport evidences of\nroom-temperature correlated electronic states and layer-hybridized SU(4)\nHubbard model simulator in AB-stacked MoS$_2$ homo-bilayer moir\\'e\nsuperlattices. Correlated insulating states at moir\\'e band filling factors v =\n1, 2, 3 are unambiguously established in twisted bilayer MoS$_2$. Remarkably,\nthe correlated electronic states can persist up to a record-high critical\ntemperature of over 285 K. The realization of room-temperature correlated\nstates in twisted bilayer MoS$_2$ can be understood as the cooperation effects\nof the stacking-specific atomic reconstruction and the resonantly enhanced\ninterlayer hybridization, which largely amplify the moir\\'e superlattice\neffects on electronic correlations. Furthermore, extreme large non-linear Hall\nresponses up to room-temperature are uncovered near correlated insulating\nstates, demonstrating the quantum geometry of moir\\'e flat conduction band.",
        "positive": "Piezomagnetic switching of anomalous Hall effect in an antiferromagnet\n  at room temperature: Piezomagnetism couples strain linearly to magnetic order producing\nmagnetization. Thus, unlike magnetostriction, it enables bidirectional control\nof a net magnetic moment. If this effect becomes large at room temperature, it\nmay be technologically relevant, similar to its electric analogue,\npiezoelectricity. To date, however, the studies of the piezomagnetic effect\nhave been primarily restricted to antiferromagnetic (AF) insulators at\ncryogenic temperatures. Here we report the discovery of a large piezomagnetism\nin a metal at room temperature. Strikingly, by using the AF Weyl semimetal\nMn$_3$Sn, known for its nearly magnetization-free anomalous Hall effect (AHE),\nwe find that an application of small uniaxial strain of the order of 0.1 % can\ncontrol both the sign and size of the AHE. Our experiment and theory show that\nthe piezomagnetism can control the AHE distinctly from the magnetization, which\nwill be useful for spintronics applications."
    },
    {
        "anchor": "Strain effects on electronic and optic properties of monolayer C$_2$N\n  holey two-dimensional crystals: A new two-dimensional material, the C$_2$N holey 2D (C$_2$N-$h$2D) crystal,\nhas recently been synthesized. Here we investigate the strain effects on the\nproperties of this new material by first-principles calculations. We show that\nthe material is quite soft with a small stiffness constant and can sustain\nlarge strains $\\geq 12\\%$. It remains a direct gap semiconductor under strain\nand the bandgap size can be tuned in a wide range as large as 1 eV.\nInterestingly, for biaxial strain, a band crossing effect occurs at the valence\nband maximum close to a 8\\% strain, leading to a dramatic increase of the hole\neffective mass. Strong optical absorption can be achieved by strain tuning with\nabsorption coefficient $\\sim10^6$ cm$^{-1}$ covering a wide spectrum. Our\nfindings suggest the great potential of strain-engineered C$_2$N-$h$2D in\nelectronic and optoelectronic device applications.",
        "positive": "Hydrostatic pressure study of paramagnetic-ferromagnetic phase\n  transition in (Ga,Mn)As: The effect of hydrostatic pressure on the paramagnetic - ferromagnetic phase\ntransition has been studied in (Ga,Mn)As. The variation of the Curie\ntemperature (TC) with pressure was monitored by two transport methods: (1) -\nmeasurement of zero field resistivity versus temperature {\\rho}(T), (2) -\ndependence on temperature of the Hall voltage hysteresis loop. Two specimens of\ndifferent resistivity characteristics were examined. The measured\npressure-induced changes of TC were relatively small (of the order of 1K/GPa)\nfor both samples, however they were opposite for the two."
    },
    {
        "anchor": "Doping of Ga in antiferromagnetic semiconductor alpha-Cr2O3oxide and its\n  effects on modified magnetic and electronic properties: The samples of Ga doped Cr2O3 oxide have been prepared using chemical\nco-precipitation route. X-ray diffraction pattern and Raman spectra have\nconfirmed rhombohedral crystal structure with space group R3-C. Magnetic\nmeasurement has indicated the dilution of antiferromagnetic (AFM) spin order in\nGa doped alpha-Cr2O3 system oxide, where the AFM transition temperature of bulk\nalpha-Cr2O3 oxide at about 320 K has been suppressed and ferrimagnetic behavior\nis observed from the analysis of the temperature dependence of magnetization\ndata below 350 K. Apart from Ga doping effect, the spin freezing (50 K-70 K)\nand superparamagnetic behavior of the surface spins at lower temperatures,\ntypically below 50 K, have been exhibited due to nano-sized grains of the\nsamples. All the samples showed non-linear current-voltage (I-V)\ncharacteristics. However, I-V characteristics of the Ga doped samples are\nremarkably different from alpha-Cr2O3 sample. The I-V curves of Ga doped\nsamples have exhibited many unique electronic properties, e.g., bi-stable (low\nresistance- LR and high resistance-HR) electronic states and negative\ndifferential resistance (NDR). Optical absorption spectra revealed three\nelectronic transitions in the samples associated with band gap energy at about\n2.67-2.81 eV, 1.91-2.11 eV, 1.28-1.35 eV, respectively.",
        "positive": "Effects of Edge Passivations on the Electronic and Magnetic Properties\n  of Zigzag Boron-Nitride Nanoribbons with Even and Odd-Line Stone-Wales (5-7\n  Pair) Defects: First-principles spin-polarized calculations have been performed on\npassivated Boron-Nitride Nanoribbons (BNNRs) with pentagon-heptagon\nline-defects (PHLDs) (also called as Stone-Wales line-defects). Two kinds of\nPHLDs, namely, even-line and odd-line PHLDs, have been added either at one edge\nor at both edges of BNNRs. Single-edge (with all its different possibilities,\nfor example, for a BNNR with 2-line PHLD at single-edge there are 8\npossibilities) as well as both-edge passivations have been considered for all\nthe ribbons in this study by passivating each edge atom with hydrogen atom.\nDensity of states (DOS) and projected-DOS (pDOS) analysis have been\naccomplished to understand the underlying reason for various properties. We\nfind that passivation lead to different effects on the electronic and magnetic\nproperties of a system, and the effects are mainly based on the line-defect\nintroduced and/or on the atoms which are present at the passivated edge. In\ngeneral, we find that, passivation can play a key role in tuning the properties\nof a system only when it has a zigzag edge."
    },
    {
        "anchor": "Hunting micrometer-sized graphene flakes on gold substrate: Gold is widely used as the substrate material in many graphene devices, due\nto its superior optoelectronic properties and chemical stability. However,\nthere has been little experimental investigation on the optical contrast of\ngraphene films on Au substrates. Here we report accurate measurement of the\noptical contrast spectra of few-layer graphene flakes on bulk Au. We used a\nhigh-resolution optical microscopy with a 100x magnification objective,\naccurately determining the thickness of flakes as small as one micrometer in\nlateral size, which are highly desired in many applications. The results are in\nexcellent agreement with theoretical calculations and confirmed by Raman and\nAFM measurements. Furthermore, we demonstrate that the optical contrast\nspectroscopy is sensitive enough to detect the adsorption of a sub-monolayer\nairborne hydrocarbon molecules, which can reveal whether graphene is\ncon-taminated and opens the opportunity to develop miniaturized and\nultrasensitive molecular sensors.",
        "positive": "Electronic and optical properties of 4H Si from first principles: The cubic polytype of silicon (Si) is the most commercialized semiconductor\nmaterial and finds applications in numerous electronic and optoelectronic\ndevices such as solar cells. However, recent reports on the synthesis of the\nhexagonal 4H Si polytype have attracted the attention of the scientific\ncommunity to understand its functional properties. Here we report the\nelectronic, vibrational, and optical properties of the 4H Si polytype obtained\nwith predictive first-principles calculations. We find that, compared to the\ncubic polytype, 4H Si shows a slightly narrower indirect gap by $\\sim$ 0.05 eV.\nBy calculating its direct and phonon-assisted optical spectra, we show that 4H\nSi exhibits a stronger absorption coefficient than cubic Si across the visible\nand IR spectral regions. We further evaluate the short-circuit current density\nof textured thin-films, and we demonstrate that 4H Si can achieve the same\nshort-circuit current density for a five times thinner film compared to the\ncubic polytype. Our work demonstrates the advantages of 4H Si for thin-film\nsilicon-based solar-cell applications."
    },
    {
        "anchor": "Microscopic theory of quantum anomalous Hall effect in graphene: We present a microscopic theory to give a physical picture of the formation\nof quantum anomalous Hall (QAH) effect in graphene due to a joint effect of\nRashba spin-orbit coupling $\\lambda_R$ and exchange field $M$. Based on a\ncontinuum model at valley $K$ or $K'$, we show that there exist two distinct\nphysical origins of QAH effect at two different limits. For $M/\\lambda_R\\gg1$,\nthe quantization of Hall conductance in the absence of Landau-level\nquantization can be regarded as a summation of the topological charges carried\nby Skyrmions from real spin textures and Merons from \\emph{AB} sublattice\npseudo-spin textures; while for $\\lambda_R/M\\gg1$, the four-band low-energy\nmodel Hamiltonian is reduced to a two-band extended Haldane's model, giving\nrise to a nonzero Chern number $\\mathcal{C}=1$ at either $K$ or $K'$. In the\npresence of staggered \\emph{AB} sublattice potential $U$, a topological phase\ntransition occurs at $U=M$ from a QAH phase to a quantum valley-Hall phase. We\nfurther find that the band gap responses at $K$ and $K'$ are different when\n$\\lambda_R$, $M$, and $U$ are simultaneously considered. We also show that the\nQAH phase is robust against weak intrinsic spin-orbit coupling $\\lambda_{SO}$,\nand it transitions a trivial phase when\n$\\lambda_{SO}>(\\sqrt{M^2+\\lambda^2_R}+M)/2$. Moreover, we use a tight-binding\nmodel to reproduce the ab-initio method obtained band structures through doping\nmagnetic atoms on $3\\times3$ and $4\\times4$ supercells of graphene, and explain\nthe physical mechanisms of opening a nontrivial bulk gap to realize the QAH\neffect in different supercells of graphene.",
        "positive": "Berry-curvatures and anomalous Hall effect in Heusler compounds: Berry curvatures are computed for a set of Heusler compounds using density\nfunctional (DF) calculations and the wave functions that DF provide. The\nanomalous Hall conductivity is obtained from the Berry curvatures. It is\ncompared with experimental values in the case of Co$_2$CrAl and Co$_2$MnAl. A\nnotable trend cannot be seen but the range of values is quite enormous. The\nresults for the anomalous Hall conductivities and their large variations can be\nqualitatively understood by means of the band structure and the Fermi-surface\ntopology."
    },
    {
        "anchor": "Modeling Disordered Materials with a High Throughput ab-initio Approach: Predicting material properties of disordered systems remains a long-standing\nand formidable challenge in rational materials design. To address this issue,\nwe introduce an automated software framework capable of modeling partial\noccupation within disordered materials using a high-throughput (HT) first\nprinciples approach. At the heart of the approach is the construction of\nsupercells containing a virtually equivalent stoichiometry to the disordered\nmaterial. All unique supercell permutations are enumerated and material\nproperties of each are determined via HT electronic structure calculations. In\naccordance with a canonical ensemble of supercell states, the framework\nevaluates ensemble average properties of the system as a function of\ntemperature. As proof of concept, we examine the framework's final calculated\nproperties of a zinc chalcogenide (ZnS$_{1-x}$Se$_x$), a wide-gap oxide\nsemiconductor (Mg$_{x}$Zn$_{1-x}$O), and an iron alloy (Fe$_{1-x}$Cu$_{x}$) at\nvarious stoichiometries.",
        "positive": "Renormalization group approach to multiscale simulation of\n  polycrystalline materials using the phase field crystal model: We propose a computationally-efficient approach to multiscale simulation of\npolycrystalline materials, based on the phase field crystal (PFC) model. The\norder parameter describing the density profile at the nanoscale is\nreconstructed from its slowly-varying amplitude and phase, which satisfy\nrotationally-covariant equations derivable from the renormalization group. We\nvalidate the approach using the example of two-dimensional grain nucleation and\ngrowth."
    },
    {
        "anchor": "Origin of the excess specific heat in metallic glass forming liquids: We report excess specific heat in a series of metallic glass forming liquids.\nIt is found that the excess specific heat relative to glass at glass transition\ntemperature Tg is constant and close to, where R is gas constant. In the\ntypical Pd40Ni10Cu30P20 metallic glass forming liquid, the excess specific heat\nis independent of temperature. A quantitative description of the excess\nspecific heat is built up. The atomic translational diffusion is the origin of\nthe excess specific heat. The results provide a fundamental understanding to\nthe glass transition in metallic glasses.",
        "positive": "Atom Based Grain Extraction and Measurement of Geometric Properties: We introduce an accurate, self-contained and automatic atom based numerical\nalgorithm to characterize grain distributions in two dimensional Phase Field\nCrystal simulations. Four input parameters must be set by the user and their\neffect is described. We compare the method with hand segmented and known test\ngrain distributions to show that the algorithm is able to extract grains and\nmeasure their area, perimeter and other geometric properties with high\naccuracy. We also compare the proposed method to a simpler but less accurate\ngrid based approach. This method is currently tuned to extract data from Phase\nField Crystal simulations in the hexagonal lattice regime but the framework may\nbe extended to more general problems."
    },
    {
        "anchor": "Wafer bonding solution to epitaxial graphene - silicon integration: The development of graphene electronics requires the integration of graphene\ndevices with Si-CMOS technology. Most strategies involve the transfer of\ngraphene sheets onto silicon, with the inherent difficulties of clean transfer\nand subsequent graphene nano-patterning that degrades considerably the\nelectronic mobility of nanopatterned graphene. Epitaxial graphene (EG) by\ncontrast is grown on an essentially perfect crystalline (semi-insulating)\nsurface, and graphene nanostructures with exceptional properties have been\nrealized by a selective growth process on tailored SiC surface that requires no\ngraphene patterning. However, the temperatures required in this structured\ngrowth process are too high for silicon technology. Here we demonstrate a new\ngraphene to Si integration strategy, with a bonded and interconnected compact\ndouble-wafer structure. Using silicon-on-insulator technology (SOI) a thin\nmonocrystalline silicon layer ready for CMOS processing is applied on top of\nepitaxial graphene on SiC. The parallel Si and graphene platforms are\ninterconnected by metal vias. This method inspired by the industrial\ndevelopment of 3d hyper-integration stacking thin-film electronic devices\npreserves the advantages of epitaxial graphene and enables the full spectrum of\nCMOS processing.",
        "positive": "Observation of Exchange Bias in Antiferromagnetic Cr$_{0.79}$Se due to\n  the Coexistence of Itinerant Weak Ferromagnetism at Low-temperatures: We report on the structural, electrical transport, and magnetic properties of\nantiferromagnetic transition-metal monochalcogenide Cr$_{0.79}$Se. Different\nfrom the existing off-stoichiometric compositions, Cr$_{0.79}$Se is found to be\nsynthesised into the same NiAs-type hexagonal crystal structure of CrSe.\nResistivity data suggest Cr$_{0.79}$Se to be a Fermi-liquid-type metal at low\ntemperatures, while at intermediate temperatures the resistivity depends\nsublinearly on the temperature. Eventually, at the elevated temperatures the\nrate of change of resistivity rapidly decreases with increasing temperature.\nMagnetic measurements suggest a transition from paramagnetic phase to an\nantiferromagnetic phase at a N$\\acute{e}$el temperature of 225 K. Further\nreduction of the sample temperature results into coexistance of weak\nferromagnetism along with the antiferromagnetic phase below 100 K. As a result,\nbelow 100 K, we identify significant exchange bias due to the interaction\nbetween the ferro- and antiferromagnetic phases. In addition, from the\ntemperature dependent X-ray diffraction measurements we observe that the\nNiAs-type structure is stable up to as high as 600$^o$C."
    },
    {
        "anchor": "Ab initio phase diagram of BaTiO$_3$ under epitaxial strain revisited: We revisit the phase diagram of BaTiO$_3$ under biaxial strain using a first\nprinciples-based effective Hamiltonian approach. We show that, in addition to\nthe tetragonal ($c$), quasi-rhombohedral ($r$), and quasi-orthorhombic ($aa$)\nferroelectric phases, that have been discussed previously, there are\ntemperature and strain regions, in particular under tensile strain, where the\nsystem decomposes into multi-domain structures. In such cases, the strained\nsystem, at least on a local level, recovers the same phase sequence as the\nunclamped bulk material. Furthermore, we extend these results from the case of\n\"uniform\" biaxial strain to the situation where the two in-plane lattice\nconstants are strained differently and show that similar considerations apply\nin this case.",
        "positive": "Quantum molecular dynamics simulations of lithium melting using Z-method: We performed first-principles molecular dynamics calculations for lithium\nusing the projector augmented waves method and the generalized gradient\napproximation as exchange-correlation energy. The melting curve of lithium was\ncomputed using the \\textit{Z}-method technique for pressures up to 30 GPa,\nwhich agrees well with the experimental and two-phase simulated results. The\nchange of the melting line slope from positive to negative was predicted by the\ncharacteristic shape inversion of the \\textit{Z} curve at about 8.2 GPa.\nThrough analyzing the static properties, we conclude that no liquid-liquid\nphase transition accompanies the occurrence of the melting line maximum, which\nis caused by the higher compressibility of the liquid phase compared to the\nsolid phase. In addition, we systematically studied the dynamic and optical\nproperties of lithium near melting curve at critical superheating and melting\ntemperatures. It was suggested that spectra difference at critical superheating\nand melting temperature may be able to diagnose the homogeneous melting."
    },
    {
        "anchor": "Accelerating crystal structure prediction by machine-learning\n  interatomic potentials with active learning: In this letter we propose a new methodology for crystal structure prediction,\nwhich is based on the evolutionary algorithm USPEX and the machine-learning\ninteratomic potentials actively learning on-the-fly. Our methodology allows for\nan automated construction of an interatomic interaction model from scratch\nreplacing the expensive DFT with a speedup of several orders of magnitude.\nPredicted low-energy structures are then tested on DFT, ensuring that our\nmachine-learning model does not introduce any prediction error. We tested our\nmethodology on a problem of prediction of carbon allotropes, dense sodium\nstructures and boron allotropes including those which have more than 100 atoms\nin the primitive cell. All the the main allotropes have been reproduced and a\nnew 54-atom structure of boron have been found at very modest computational\nefforts.",
        "positive": "Electrically controllable surface magnetism on the surface of\n  topological insulator: We study theoretically the RKKY interaction between magnetic impurities on\nthe surface of three-dimensional topological insulators, mediated by the\nhelical Dirac electrons. Exact analytical expression shows that the RKKY\ninteraction consists of the Heisenberg-like, Ising-like and DM-like terms. It\nprovides us a new way to control surface magnetism electrically. The gap opened\nby doped magnetic ions can lead to a short-range Bloembergen-Rowland\ninteraction. The competition among the Heisenberg, Ising and DM terms leads to\nrich spin configurations and anomalous Hall effect on different lattices."
    },
    {
        "anchor": "Mg nanostructures with controlled dominant c-plane or m-plane facets by\n  DC magnetron sputter deposition: Magnesium nanostructures find increased use in applications for hydrogen\nstorage, catalysis, waste treatment, and heat storage to name a few. Currently,\nmost nanoparticles are made using a chemical synthesis approach, necessitating\nthe use of organic solvents and yielding material covered in ligands. To apply\nthese nanoparticles, one has to use them in paints or slurries for coating of\nsurfaces, which again produces waste. In this communication we explore the\npossibilities of making magnesium nanostructures by a physical technique of\nmagnetron sputtering and to control their crystallographic properties, i.e. the\ntype of the dominating crystalline faces building up the external surface of\nthe particle. We show that by applying different process parameters, it is\npossible to obtain dominating c-plane, mixed or dominating m-plane\nnanostructures. Since the surface-related adsorption processes are strongly\nrelated to the type of the crystalline plane, this report presents a clean,\nwaste-free and large-scale approach to develop tailored nanostructured Mg\ncoatings.",
        "positive": "{\\it Ab initio} determination of the phase diagram of CO$_2$ at high\n  pressures and temperatures: The experimental study of the CO$_2$ phase diagram is hampered by strong\nkinetic effects leading to wide regions of metastability and to large\nuncertainties in the location of phase boundaries. Here we determine the CO$_2$\nphase boundaries by means of {\\it ab initio} calculations of the Gibbs free\nenergy of several molecular and non-molecular solid phases of CO$_2$.\nTemperature effects are included in the quasi-harmonic approximation. Contrary\nto previous results, we find that the boundary between non-molecular phases and\nphase V has a positive slope and starts at 21.5 GPa at $T$ = 0 K. A triple\npoint between phase IV, V, and the liquid phase is found at 35 GPa and 1600 K,\nindicating a broader region of stability for the non-molecular phases than\npreviously thought. The experimentally determined boundary line between\nCO$_{2}$-II and CO$_{2}$-IV phases is reproduced by our calculations,\nindicating that kinetic effects are not relevant in that transition."
    },
    {
        "anchor": "Pressure-induced optical anisotropy of HfS$_2$: The effect of pressure on Raman scattering (RS) in the bulk HfS$_2$ is\ninvestigated under hydrostatic and non-hydrostatic conditions. The RS lineshape\ndoes not change significantly in the hydrostatic regime, showing a systematic\nblueshift of the spectral features. In a non-hydrostatic environment, seven\npeaks emerge in the spectrum ($P$=7 GPa) dominating the lineshape up to\n$P$=10.5 GPa. The change in the RS lineshape manifests a pressure-induced phase\ntransition in HfS$_2$. The simultaneous observation of both low-pressure (LP)\nand high-pressure (HP) related RS peaks suggests the corresponding coexistence\nof two different phases over a large pressure range. We found that the\nHP-related phase is metastable, persisting during the decompression cycle down\nto $P$=1.2 GPa with the LP-related features finally recovering at even lower\npressures. The angle-resolved polarized RS (ARPRS) performed under $P$=7.4 GPa\nrevealed a strong in-plane anisotropy of both the LP-related A$_{1g}$ mode and\nthe HP peaks. The anisotropy is related to the possible distortion of the\nstructure induced by the non-hydrostatic component of the pressure. We describe\nthe obtained results by the influence of the non-hydrostatic pressure on the\nobserved phase transition. We interpret our results in terms of a distorted\n$Pnma$ phase as a possible HP induced structure of HfS$_2$.",
        "positive": "Domain walls within domain walls in wide ferromagnetic strips: We carry out large-scale micromagnetic simulations which demonstrate that due\nto topological constraints, internal domain walls (Bloch lines) within extended\ndomain walls are more robust than domain walls in nanowires. Thus, the\npossibility of spintronics applications based on their motion channeled along\ndomain walls emerges. Internal domain walls are nucleated within domain walls\nin perpendicularly magnetized media concurrent with a Walker breakdown-like\nabrupt reduction of the domain wall velocity above a threshold driving force,\nand may also be generated within pinned, localized domain walls. We observe\nfast field and current driven internal domain wall dynamics without a Walker\nbreakdown along pinned domain walls, originating from topological protection of\nthe internal domain wall structure due to the surrounding out-of-plane domains."
    },
    {
        "anchor": "Lattice dynamics and thermophysical properties of h.c.p. Re and Tc from\n  the quasi-harmonic approximation: We report first-principles phonon frequencies and anharmonic thermodynamic\nproperties of h.c.p. Re and Tc calculated within the quasi-harmonic\napproximation, including Gr\\\"uneisen parameters, temperature-dependent lattice\nparameters, thermal expansion, and isobaric heat capacity. We discuss the\ndifferences between a full treatment of anisotropy and a simplified approach\nwith a constant $c/a$ ratio. The results are systematically compared with the\navailable experimental data and an overall satisfactory agreement is obtained.",
        "positive": "Magnetic exchange interactions in SrMnO$_3$: We calculate Heisenberg-type magnetic exchange interactions for SrMnO$_3$\nunder isotropic volume expansion using an approach that is based on total\nenergy variations due to infinitesimal spin rotations around a given reference\nstate. Our total energy calculations using density functional theory (DFT)\nindicate a transition from antiferromagnetic to ferromagnetic coupling for\nincreasing interatomic distances, corresponding to a sign change of the nearest\nneighbor exchange interaction. This sign change cannot easily be understood\nfrom a standard superexchange mechanism. Furthermore, the exchange interaction\nstrongly depends on the corresponding reference state. This \"non-Heisenberg\"\nbehavior increases with increasing volume and is also confirmed through\nnon-collinear DFT calculations. An orbital- and energy-resolved decomposition\nof the exchange coupling suggests that an increased partial occupancy of $e_g$\norbitals near the Fermi level is crucial both for the sign change and the\nnon-Heisenberg behavior of the nearest neighbor interaction. Furthermore, even\nthough both $e_g$ and $t_{2g}$ contributions to the exchange interactions decay\nexponentially for large inter-atomic distances, the $e_g$ contribution remains\nsurprisingly strong over relatively large distances along the crystal axes."
    },
    {
        "anchor": "Prediction of superconductivity and topological aspects in single-layer\n  $\u03b2$-Bi$_{2}$Pd: Topological superconductors, characterized by topologically nontrivial states\nresiding in a superconducting gap, are a recently discovered class of materials\nhaving Majorana Fermions. The interplay of superconductivity and topological\nstates give rise to opportunities for achieving such topological\nsuperconductors in condensed matter systems. Up to now, several single-material\ntopological superconductors in this form have been theoretically predicted and\nexperimentally confirmed. Here, using the first-principles calculations, we\nstudy the superconducting single-layer $\\beta$-Bi$_{2}$Pd. The electronic\ndensity of states near Fermi level of this monolayer are dominated by the Bi-p\nand Pd-d orbitals, forming a two-band Fermi surface with multi-class sheets.\nThe presence of soft phonon bands, in cooperation with the electron\nsusceptibility, account for electron-phonon superconductivity of single-layer\n$\\beta$-Bi$_{2}$Pd. With the centrosymmetric structure, single-layer\n$\\beta$-Bi$_{2}$Pd possesses a continuous gap over the whole Brillouin zone and\ntopological Dirac-like states at its one-dimensional boundary. The present\nfindings would lead to the expectation of one-dimensional topological\nsuperconductivity and Majorana bound states in monolayer candidate of\n$\\beta$-Bi$_{2}$Pd with intrinsic full-gap superconductivity.",
        "positive": "Revealing fingerprints of valence excitons in x-ray absorption spectra\n  with the Bethe-Salpeter equation: The Bethe-Salpeter equation (BSE) is a powerful theoretical approach that is\ncapable to accurately treat electron-hole interactions in materials in an\nexcited state. We developed an ab initio framework based on the BSE to describe\na pump-probe experiment, in which an x-ray pulse probes solid-state valence\nexcitons by means of x-ray absorption spectroscopy. Our theoretical framework\nis of relevance for an accurate modeling of pump-probe experiments of\nphoto-excited materials that utilize novel capabilities offered by x-ray\nscience."
    },
    {
        "anchor": "Surface Chemistry and Electrical Properties of Germanium Nanowires: Germanium nanowires with p- and n-dopants were synthesized by chemical vapor\ndeposition and used to construct complementary field effect transistors .\nElectrical transport and x-ray photoelectron spectroscopy data are correlated\nto glean the effects of Ge surface chemistry to the electrical characteristics\nof GeNWs. Large hysteresis due to water molecules strongly bound to GeO2 on\nGeNWs is revealed. Different oxidation behavior and hysteresis characteristics\nand opposite band bending due to Fermi level pinning by interface states\nbetween Ge and surface oxides are observed for p- and n-type GeNWs. Vacuum\nannealing above 400C is used to remove surface oxides and eliminate hysteresis\nin GeNW FETs. High-k dielectric HfO2 films grown on clean GeNW surfaces by\natomic layer deposition (ALD) using an alkylamide precursor is effective\nserving as the first layer of surface passivation. Lastly, the depletion length\nalong the radial direction of nanowires is evaluated. The result suggests that\nsurface effects could be dominant over the bulk properties of small diameter\nwires.",
        "positive": "Local electronic excitations by slow light ions in tungsten: Accurately predicting the electronic energy deposition of ions in materials\nis an important challenge in both fundamental and applied research. While\nemploying ab initio simulations to investigate electronic stopping of ions in\nmatter holds promise, its combined use with experimental measurements paves the\nway for obtaining reliable data. In this paper, we present a collaborative\nstudy using real-time time-dependent density functional theory and experimental\nmethods to determine the electronic stopping power of hydrogen and helium ions\nin tungsten, a primary candidate material for future nuclear fusion devices.\nWhile calculated stopping powers in hyperchanneling trajectories are\nsignificantly lower than the experimental data, off-center and random\ngeometries demonstrate a better agreement. We show that the deviation from\nvelocity proportionality for both projectiles traversing the hyperchanneling\ndirections can be explained through the existence of a threshold velocity\nleading to the activation of semicore states. Additionally, we analyse the\npseudopotential and the trajectory dependence of computed electronic energy\nlosses. It is demonstrated that the role of including inner-shell electrons\nvaries depending on the velocity range. While these states play a crucial role\nat high projectile velocities by introducing additional dissipation channels,\ntheir impact diminishes in the low-velocity range. Finally, we introduce a\nsimple expression that links electronic energy losses in different trajectories\nto local electron density, and we show that utilizing this formula allows for\nquite accurate predictions of stopping powers around the Bragg peak."
    },
    {
        "anchor": "Thermal Stability of Hafnium Zirconium Oxide on Transition Metal\n  Dichalcogenides: Ferroelectric oxides interfaced with transition metal dichalcogenides (TMDCs)\noffer a promising route toward ferroelectric-based devices due to lack of\ndangling bonds on the TMDC surface leading to a high-quality and abrupt\nferroelectric/TMDC interface. In this work, the thermal stability of this\ninterface is explored by first depositing hafnium zirconium oxide (HZO)\ndirectly on geological MoS2 and as-grown WSe2, followed by sequential annealing\nin ultra-high vacuum (UHV) over a range of temperatures (400-800 {\\deg}C), and\nexamining the interface through X-ray photoelectron spectroscopy (XPS). We show\nthat the nucleation and stability of HZO grown through atomic layer deposition\n(ALD) varied depending on functionalization of the TMDC, and the deposition\nconditions can cause tungsten oxidation in WSe2. It was observed that HZO\ndeposited on non-functionalized MoS2 was unstable and volatile upon annealing,\nwhile HZO on functionalized MoS2 was stable in the 400-800 {\\deg}C range. The\nHZO/WSe2 interface was stable until 700 {\\deg}C, after which Se began to evolve\nfrom the WSe2. In addition, there is evidence of oxygen vacancies in the HZO\nfilm being passivated at high temperatures. Lastly, X-ray diffraction (XRD) was\nused to confirm crystallization of the HZO within the temperature range\nstudied.",
        "positive": "Multiple soft-mode vibrations of lead zirconate: Polarized Raman, IR and time-domain THz spectroscopy of orthorhombic lead\nzirconate single crystals yielded a comprehensive picture of\ntemperature-dependent quasiharmonic frequencies of its low-frequency phonon\nmodes. It is argued that these modes primarily involve vibration of Pb and/or\noxygen octahedra librations and their relation to particular phonon modes of\nthe parent cubic phase is proposed. Counts of the observed IR and Raman active\nmodes belonging to distinct irreducible representations agree quite well with\ngroup-theory predictions. The most remarkable finding is the considerably\nenhanced frequency renormalization of the y-polarized polar modes, resulting in\na pronounced low temperature dielectric anisotropy. Results are discussed in\nterms of contemporary phenomenological theory of antiferroelectricity."
    },
    {
        "anchor": "Fully Periodic, Computationally Efficient Constant Potential Molecular\n  Dynamics Simulations of Ionic Liquid Supercapacitors: Molecular dynamics (MD) simulations of complex electrochemical systems, such\nas ionic liquid supercapacitors, are increasingly including the constant\npotential method (CPM) to model conductive electrodes at specified potential\ndifference, but the inclusion of CPM can be computationally expensive. We\ndemonstrate the computational savings available in CPM MD simulations of ionic\nliquid supercapacitors when the usual non-periodic slab geometry is replaced\nwith fully periodic boundary conditions. We show how a doubled cell approach,\npreviously used in non-CPM MD simulations of charged interfaces, can be used to\nenable fully periodic CPM MD simulations. Using either a doubled cell approach,\nor a finite field approach previously reported by others, fully periodic CPM MD\nsimulations produce comparable results to the traditional slab geometry\nsimulations with a nearly double speed-up in computational time. Indeed, these\nsavings can offset the additional cost of the CPM algorithm, resulting in\nperiodic CPM MD simulations that are faster than the non-periodic, fixed-charge\nequivalent simulations for the ionic liquid supercapacitors studied here.",
        "positive": "Periodically Spaced CaF$_2$ Semi-Insulating Thin Ribbons Growth Study on\n  the Si(100) Surface: The use and the study of semi-insulating layers on metals and semiconductors\nsurfaces have found continuous interest in the past decades. So far, the\ncontrol of the sizes and growth location of the insulating islands on the\nsubstrate is either ill-defined or usually constrained to the use of\nevaporation masks which size can easily exceed tenth of nanometers. Here, we\nshow that it is possible to grow self-organized periodically spaced thin\nribbons of semi-insulating stripes on the bare Si(100) surface. The epitaxial\ngrowth of these structures is obtained by the evaporation of CaF$_2$ molecules\non the silicon surface with a coverage of 1.2 monolayers. They are investigated\nvia scanning tunneling techniques at low temperature (9K). The obtained ribbons\nexhibit a surface bandgap of ~3.2 eV as well as a resonant state at the central\npart of the ribbons at ~2.0 eV below the Fermi level energy. The use of the\ndensity functional theory allows suggesting a model structure of the observed\nribbons and reproducing the experimental STM topographies. The formation of the\nthin ribbons is discussed and we point out the influence of the mechanical\nforces inside and between the structures that may influence their periodicity."
    },
    {
        "anchor": "Island Size Selectivity and island-shape analysis during 2D Island\n  Coarsening of Ag/Ag (111) Surface: In our earlier study of Ag island coarsening on Ag(111) surface using kinetic\nMonte Carlo (KMC) simulations we found that during early stages coarsening\nproceeds as a sequence of selected island sizes resulting in peaks and valleys\nin the island-size distribution and that this selectivity is independent of\ninitial conditions and dictated instead by the relative energetics of edge-atom\ndiffusion and detachment/attachment processes and by the large activation\nbarrier for kink detachment. In this paper we present a detailed analysis of\nthe shapes of various island sizes observed during these KMC simulations and\nshow that selectivity is due to the formation of kinetically stable island\nshapes which survive longer than non-selected sizes, which decay into nearby\nselected sizes. The stable shapes have a closed-shell structure - one in which\nevery atom on the periphery having at least three nearest neighbors. Our KMC\nsimulations were carried out using a very large database of processes\nidentified by each atom's unique local environment, the activation barriers of\nwhich were calculated using semi-empirical interaction potentials based on the\nembedded-atom method.",
        "positive": "Displacement cascades and defects annealing in tungsten, Part I: defect\n  database from molecular dynamics simulations: Molecular dynamics simulations have been used to generate a comprehensive\ndatabase of surviving defects due to displacement cascades in bulk tungsten.\nTwenty one data points of primary knock-on atom (PKA) energies ranging from 100\neV (sub-threshold energy) to 100 keV ($\\sim$780$\\times E_d$, where $E_d$ is the\naverage displacement threshold energy) have been completed at 300 K, 1025 K and\n2050 K. Within this range of PKA energies, two regimes of power-law\nenergy-dependence of the defect production are observed. A distinct power-law\nexponent characterizes the number of Frenkel pairs produced within each regime.\nThe two regimes intersect at a transition energy which occurs at approximately\n250$\\times E_d$. The transition energy also marks the onset of the formation of\nlarge self-interstitial atom (SIAs) clusters (size 14 or more). The observed\ndefect clustering behavior is asymmetric, with SIA clustering increasing with\ntemperature, while the vacancy clustering decreases. This asymmetry increases\nwith temperature such that at 2050 K ($\\sim 0.5 T_m$) practically no large\nvacancy clusters are formed, meanwhile large SIA clusters appear in all\nsimulations. The implication of such asymmetry on the long-term defect survival\nand damage accumulation is discussed. In addition, rare $<$100$>${110} SIA\nloops are observed."
    },
    {
        "anchor": "Dopant redistribution and activation in Ga ion-implanted high Ge content\n  SiGe by explosive crystallization during UV nanosecond pulsed laser annealing: Explosive crystallization (EC) is often observed when using nanosecond-pulsed\nmelt laser annealing (MLA) in amorphous silicon (Si) and germanium (Ge). The\nsolidification velocity in EC is so fast that a diffusion-less crystallization\ncan be expected. In the contacts of advanced transistors, the active level at\nthe metal/semiconductor Schottky interface must be very high to achieve a\nsub-10^{-9} ohm.cm2 contact resistivity, which has been already demonstrated by\nusing the dopant surface segregation induced by MLA. However, the beneficial\nlayer of a few nanometers at the surface may be easily consumed during\nsubsequent contact cleaning and metallization. EC helps to address such kind of\nprocess integration issues, enabling the optimal positioning of the peak of the\ndopant chemical profile. However, there is a lack of experimental studies of EC\nin heavily-doped semiconductor materials. Furthermore, to the best of our\nknowledge, dopant activation by EC has never been experimentally reported. In\nthis paper, we present dopant redistribution and activation by an EC process\ninduced by UV nanosecond-pulsed MLA in heavily gallium (Ga) ion-implanted high\nGe content SiGe. Based on the obtained results, we also highlight potential\nissues of integrating EC into real device fabrication processes and discuss how\nto manage them.",
        "positive": "Polysiloxane surfactants for the dispersion of carbon nanotubes in\n  non-polar organic solvents: We develop two new amphiphilic molecules that are shown to act as efficient\nsurfactants for carbon nanotubes in non-polar organic solvents. The active\nconjugated groups, which are highly attracted to graphene nanotube surface, are\nbased on pyrene and porphyrin. We show that relatively short (C18) carbon tails\nare insufficient to provide stabilization. As our ultimate aim is to disperse\nand stabilize nanotubes in siloxane matrix (polymer and crosslinked elastomer),\nboth surfactant molecules were made with long siloxane tails to facilitate\nsolubility and steric stabilization. We show that pyrene-siloxane surfactant is\nvery effective in dispersing multi-wall nanotubes, while the porphyrin-siloxane\nis making single-wall nanotubes soluble, both in petroleum ether and in\nsiloxane matrix."
    },
    {
        "anchor": "Surface magnetic anisotropy at a compensated interface of ferromagnetic\n  antiferromagnetic bilayer: The periodic deviations of ferromagnetic and antiferromagnetic spins from\ncorresponding uniform configurations are shown to be energetically favorable\nclose to a compensated interface of ferromagnetic antiferromagnetic bilayer.\nThe amplitude of the deviations decreases exponentially into the film volumes\nas a function of a coordinate perpendicular to the interface. The interaction\nenergy is found to be proportional to a square of a scalar product of unit\nferromagnetic and antiferromagnetic vectors.",
        "positive": "Superparamagnetism induced by polar nanoregions in relaxor ferroelectric\n  (1$-$$x$)BiFeO$_{3}$-$x$BaTiO$_{3}$: A new class of superparamagnetism was found in relaxor ferroelectric\n2/3BiFeO$_{3}$-1/3BaTiO$_{3}$. The size of the magnetic particle, estimated\nfrom the superparamagnetic magnetization curve, coincides with the size of the\npolar nanoregion (PNR), which governs the relaxor ferroelectric property. This\nsuggests that the magnetic domain is identical to the PNR. The temperature\nvariations in the sizes of the magnetic domains and PNRs estimated by our\nneutron diffraction measurements support this picture. Since the same domain\nprovides both electric and magnetic properties, strong coupling between the two\nproperties through the domain size is expected."
    },
    {
        "anchor": "Band dispersion in the deep 1s core level of graphene: Chemical bonding in molecules and solids arises from the overlap of valence\nelectron wave functions, forming extended molecular orbitals and dispersing\nBloch states, respectively. Core electrons with high binding energies, on the\nother hand, are localized to their respective atoms and their wave functions do\nnot overlap significantly. Here we report the observation of band formation and\nconsiderable dispersion (up to 60 meV) in the $1s$ core level of the carbon\natoms forming graphene, despite the high C $1s$ binding energy of $\\approx$ 284\neV. Due to a Young's double slit-like interference effect, a situation arises\nin which only the bonding or only the anti-bonding states is observed for a\ngiven photoemission geometry.",
        "positive": "Structure effect on intrinsic piezoelectricity in septuple-atomic-layer\n  $\\mathrm{MSi_2N_4}$ (M=Mo and W): The recently experimentally synthesized monolayer $\\mathrm{MoSi_2N_4}$ and\n$\\mathrm{WSi_2N_4}$ (\\textcolor[rgb]{0.00,0.00,1.00}{Science 369, 670-674\n(2020})) lack inversion symmetry, which allows them to become piezoelectric. In\nthis work, based on ab initio calculations, we report structure effect on\nintrinsic piezoelectricity in septuple-atomic-layer $\\mathrm{MSi_2N_4}$ (M=Mo\nand W), and six structures ($\\alpha_i$ ($i$=1 to 6)) are considered with the\nsame space group.It is found that $\\mathrm{MSi_2N_4}$ (M=Mo and W) with\n$\\alpha_i$ ($i$=1 to 6) all are indirect band gap semiconductors. Calculated\nresults show that $\\mathrm{MoSi_2N_4}$ and $\\mathrm{WSi_2N_4}$ monolayers have\nthe same structural dependence on piezoelectric strain and stress coefficients\n($d_{11}$ and $e_{11}$), together with the ionic and electronic contributions\nto $e_{11}$.Finally, we investigate the intrinsic piezoelectricity of monolayer\n$\\mathrm{MA_2Z_4}$ (M=Cr, Mo and W; A=Si and Ge; Z=N and P) with $\\alpha_1$ and\n$\\alpha_2$ phases expect $\\mathrm{CrGe_2N_4}$, because they all are\nsemiconductors and their enthalpies of formation between $\\alpha_1$ and\n$\\alpha_2$ phases are very close. The most important result is that monolayer\n$\\mathrm{MA_2Z_4}$ containing P atom have more stronger piezoelectric\npolarization than one including N atom. The largest $d_{11}$ among\n$\\mathrm{MA_2N_4}$ materials is 1.85 pm/V, which is close to the smallest\n$d_{11}$ of 1.65 pm/V in $\\mathrm{MA_2P_4}$ monolayers. For $\\mathrm{MA_2P_4}$,\nthe largest $d_{11}$ is up to 6.12 pm/V. Among the 22 monolayers,\n$\\alpha_1$-$\\mathrm{CrSi_2P_4}$, $\\alpha_1$-$\\mathrm{MoSi_2P_4}$,\n$\\alpha_1$-$\\mathrm{CrGe_2P_4}$, $\\alpha_1$-$\\mathrm{MoGe_2P_4}$ and\n$\\alpha_2$-$\\mathrm{CrGe_2P_4}$ have large $d_{11}$, which are greater than or\nclose to 5 pm/V, a typical value for bulk piezoelectric materials."
    },
    {
        "anchor": "Crystal orientation and detector distance effects on resolving\n  pseudosymmetry by electron backscatter diffraction: Accurately indexing pseudosymmetric materials has long proven challenging for\nelectron backscatter diffraction. The recent emergence of intensity-based\nindexing approaches promises an enhanced ability to resolve pseudosymmetry\ncompared to traditional Hough-based indexing approaches. However, little work\nhas been done to understand the effects of sample position and orientation on\nthe ability to resolve pseudosymmetry, especially for intensity-based indexing\napproaches. Thus, in this work we quantitatively investigate the effects of\ncrystal orientation and detector distance in a model tetragonal ZrO2\n(c/a=1.0185) material. We identify orientations that are easiest and most\ndifficult to correctly index, characterize the effect of detector distance on\nindexing confidence, and analyze these trends based on the appearance of\nspecific zone axes in the diffraction patterns. Our findings also point to the\nclear benefit of shorter detector distances for resolving pseudosymmetry using\nintensity-based indexing approaches.",
        "positive": "Computational approach to finite size and shape effects in iron\n  nanomagnets: We develop and validate a computational approach to nanomagnets. It is built\non the spin wave approximation to a Heisenberg ferromagnet whose parameters can\nbe calculated from a first principles theory (e.g. density functional theory).\nThe method can be used for high throughput analysis of a variety of\nnanomagnetic materials. We compute the dependence of the magnetization of an\niron nanomagnet on temperature, size and shape. The approach is applied to\nnanomagnets in the range of 432 atoms to 59 million atoms, a size which is\nseveral orders of magnitude beyond the scalability of density functional\ntheory."
    },
    {
        "anchor": "Peculiarities of the transport properties of InMnAs layers, produced by\n  the laser deposition, in strong magnetic fields: Magnetotransport properties of p-InMnAs layers are studied in pulsed magnetic\nfields up to 30 T. Samples were prepared by the laser deposition and annealed\nby ruby laser pulses. Well annealed samples show p-type conductivity while they\nwere n-type before the annealing. Surprisingly the anomalous Hall effect\nresistance in paramagnetic state (T>40 K) and in strong magnetic fields (B > 20\nT) appears to be greater than that in ferromagnetic state (T <= 40 K), while\nthe longitudinal resistance rises with the temperature decrease. The negative\nmagnetoresistance saturates in magnetic fields higher then 10T at T near 4 K\nonly, whereas the saturation fields of the anomalous Hall effect resistance are\nmuch less (around 2 T at 30K). The total reduction of resistance exceeds 10\ntimes in magnetic fields around of 10T. The obtained results are interpreted on\nthe base of the assumptions of the non-uniform distribution of Mn atoms acting\nas acceptors, the local ferromagnetic transition and the percolation-like\ncharacter of the film conductivity, which prevailed under conditions of the\nstrong fluctuations of the exchange interaction. Characteristic scales of the\nmagneto-electric nonuniformity are estimated using analysis of the mesoscopic\nfluctuations of the non-diagonal components of the magnetoresistivity tensor.",
        "positive": "Monte Carlo simulations study of the intermetallic compound\n  NdCo$_2$Si$_2$ Magnetic properties: Magnetic properties of the intermetallic compound NdCo$_2$Si$_2$ are\ninvestigated by using the Monte Carlo simulation (MCs) under Metropolis\nalgorithm. The magnetism of the compound is caused by the existence of the rare\nearth (Nd3+) ions with a magnetic moment taking the value 2.7 muB. Firstly, the\nground state phase diagrams are presented and discussed in different planes\ncorresponding to different physical parameters of the system. The stable phases\nare explored for different configurations of the Hamiltonian of the system.\nThese stable phases are determined by the minimal energies. For non-null\ntemperature values, we compute the magnetizations and susceptibilities\nbehaviors as a function of temperature by using the Monte Carlo simulations\n(MCS). Also, we present the magnetization behaviors as a function of the\nexchange coupling interactions, the crystal field and the external magnetic\nfield. Finally, we present and discuss the magnetic hysteresis loops of the\nintermetallic NdCo2Si2 compound as a function of the external magnetic field\nfor fixed values of temperature and the other physical parameters."
    },
    {
        "anchor": "Excited quantum Hall effect: enantiomorphic flat bands in a Yin-Yang\n  Kagome lattice: Quantum Hall effect (QHE) is one of the most fruitful research topics in\ncondensed-matter physics. Ordinarily, the QHE manifests in a ground state with\ntime-reversal symmetry broken by magnetization to carry a quantized chiral edge\nconductivity around a two-dimensional insulating bulk. We propose a theoretical\nconcept and model of non-equilibrium excited-state QHE (EQHE) without intrinsic\nmagnetization. It arises from circularly polarized photoexcitation between two\nenantiomorphic flat bands of opposite chirality, each supporting originally a\nhelical topological insulating state hosted in a Yin-Yang Kagome lattice. The\nchirality of its edge state can be reversed by the handedness of light, instead\nof the direction of magnetization as in the conventional quantum (anomalous)\nHall effect, offering a simple switching mechanism for quantum devices.\nImplications and realization of EQHE in real materials are discussed.",
        "positive": "Electronic structure of InAs and InSb surfaces: density functional\n  theory and angle-resolved photoemission spectroscopy: The electronic structure of surfaces plays a key role in the properties of\nquantum devices. However, surfaces are also the most challenging to simulate\nand engineer. Here, we study the electronic structure of InAs(001), InAs(111),\nand InSb(110) surfaces using a combination of density functional theory (DFT)\nand angle-resolved photoemission spectroscopy (ARPES). We were able to perform\nlarge-scale first principles simulations and capture effects of different\nsurface reconstructions by using DFT calculations with a machine-learned\nHubbard U correction [npj Comput. Mater. 6, 180 (2020)]. To facilitate direct\ncomparison with ARPES results, we implemented a \"bulk unfolding\" scheme by\nprojecting the calculated band structure of a supercell surface slab model onto\nthe bulk primitive cell. For all three surfaces, we find a good agreement\nbetween DFT calculations and ARPES. For InAs(001), the simulations clarify the\neffect of the surface reconstruction. Different reconstructions are found to\nproduce distinctive surface states. For InAs(111) and InSb(110), the\nsimulations help elucidate the effect of oxidation. Owing to larger charge\ntransfer from As to O than from Sb to O, oxidation of InAs(111) leads to\nsignificant band bending and produces an electron pocket, whereas oxidation of\nInSb(110) does not. Our combined theoretical and experimental results may\ninform the design of quantum devices based on InAs and InSb semiconductors,\ne.g., topological qubits utilizing the Majorana zero modes."
    },
    {
        "anchor": "Structural diversity of molecular nitrogen on approach to polymeric\n  states: Nitrogen represents an archetypal example of material exhibiting a pressure\ndriven transformation from molecular to polymeric state. Detailed\ninvestigations of such transformations are challenging because of a large\nkinetic barrier between molecular and polymeric structures, making the\ntransformation largely dependent on kinetic stimuli. In the case of nitrogen,\nadditional complications occur due to the rich polymorphism in the vicinity of\nthe transition. Here, we report the observation of both molecular (\\theta) and\npolymeric (BP) phases, crystallized upon temperature quenching of fluid\nnitrogen to room temperature at 97-114 GPa. Synchrotron single-crystal X-ray\ndiffraction, Raman spectroscopy, and first-principles theoretical calculations\nhave been used for diagnostics of the phases and determination of their\nstructure and stability. Molecular \\theta-nitrogen is the most stable among\nmolecular phases bordering the stability field of polymeric phases, partially\nsettling a previously noted discrepancy between theory and experiment\nconcerning the thermodynamic stability limit of molecular phases.",
        "positive": "Phase transitions in random magnetic bilayer: The influence of random interlayer exchange on the phase states of the\nsimplest magnetic heterostructure consisting of two ferromagnetic Ising layers\nwith large interaction radius is studied. It is shown that such system can\nexist in three magnetic phases: ferromagnetic, antiferromagnetic and\nferrimagnetic. The possible phase diagrams and temperature dependencies of\nthermodynamic parameters are described. The regions of existence of the\nmagnetic phases in external magnetic field are determined at zero temperature."
    },
    {
        "anchor": "A periodic equation-of-motion coupled-cluster implementation applied to\n  $F$-centers in alkaline earth oxides: We present an implementation of equation of motion coupled-cluster singles\nand doubles (EOM-CCSD) theory using periodic boundary conditions and a plane\nwave basis set. Our implementation of EOM-CCSD theory is applied to study\n$F$-centers in alkaline earth oxides employing a periodic supercell approach.\nThe convergence of calculated electronic excitation energies for neutral color\ncenters in MgO, CaO and SrO crystals with respect to orbital basis set and\nsystem size is explored. We discuss extrapolation techniques that approximate\nexcitation energies in the complete basis set limit and reduce finite size\nerrors. Our findings demonstrate that EOM-CCSD theory can predict optical\nabsorption energies of $F$-centers in good agreement with experiment.\nFurthermore, we discuss calculated emission energies corresponding to the decay\nfrom triplet to singlet states, responsible for the photoluminescence\nproperties. Our findings are compared to experimental and theoretical results\navailable in literature.",
        "positive": "Recent progress in perpendicularly magnetized Mn-based binary alloy\n  films: In this article, we review the recent progress in growth, structural\ncharacterization, magnetic properties and related spintronic devices of\ntetragonal MnxGa and MnxAl thin films with perpendicular magnetic anisotropy.\nIn the first part of this review, we present a brief introduction to the\ndemands for perpendicularly magnetized materials in spintronics, magnetic\nrecording and permanent magnets applications, and the most promising candidates\nof tetragonal MnxGa and MnxAl with strong perpendicular anisotropy. Then, in\nthe second and third parts, we focus on the recent progress of perpendicularly\nmagnetized MnxGa and MnxAl, respectively, including their lattice structures,\nbulk synthesis, epitaxial growth, structural chracterizations, magnetic and\nother spin-dependent properties, and spintronic devices like magnetic tunneling\njunctions, spin valves and spin injector into semiconductors. Finally, we give\na summary and a perspective of these perpendicularly magnetized Mn-based binary\nalloy films for future applications."
    },
    {
        "anchor": "Symmetry breaking induced insulating electronic state in\n  Pb$_{9}$Cu(PO$_4$)$_6$O: The recent experimental claim of room-temperature ambient-pressure\nsuperconductivity in a Cu-doped lead-apatite (LK-99) has ignited substantial\nresearch interest in both experimental and theoretical domains. Previous\ndensity functional theory (DFT) calculations with the inclusion of an on-site\nHubbard interaction $U$ consistently predict the presence of flat bands\ncrossing the Fermi level. This is in contrast to DFT plus dynamical mean field\ntheory calculations, which reveal the Mott insulating behavior for the\nstoichiometric Pb$_{9}$Cu(PO$_4$)$_6$O compound. Nevertheless, the existing\ncalculations are all based on the $P6_3/m$ structure, which is argued to be not\nthe ground-state structure. Here, we revisit the electronic structure of\nPb$_{9}$Cu(PO$_4$)$_6$O with the energetically more favorable $P\\bar{3}$\nstructure, fully taking into account electronic symmetry breaking. We examine\nall possible configurations for Cu substituting the Pb sites. Our results show\nthat the doped Cu atoms exhibit a preference for substituting the Pb2 sites\nthan the Pb1 sites. In both cases, the calculated substitutional formation\nenergies are large, indicating the difficulty in incorporating Cu at the Pb\nsites. We find that most of structures with Cu at the Pb2 site tend to be\ninsulating, while the structures with both two Cu atoms at the Pb1 sites\n(except one configuration) are predicted to be metallic by DFT+$U$\ncalculations. However, when accounting for the electronic symmetry breaking,\nsome Cu-doped configurations previously predicted to be metallic (including the\nstructure studied in previous DFT+$U$ calculations) become insulating. Our work\nhighlights the importance of symmetry breaking in obtaining correct electronic\nstate for Pb$_{9}$Cu(PO$_4$)$_6$O, thereby reconciling previous DFT+$U$ and\nDFT+DMFT calculations.",
        "positive": "Interplay of epitaxial strain and rotations in PbTiO$_3$/PbZrO$_3$\n  superlattices from first principles: We present first-principles calculations of the structural phase behavior of\nthe [1:1] \\pzta\\ superlattice and the \\ptoa\\ and \\pzoa\\ parent compounds as a\nfunction of in-plane epitaxial strain. A symmetry analysis is used to identify\nthe phases and clarify how they arise from an interplay between different kinds\nof structural distortions, including out-of-plane and in-plane polar modes,\nrotation of oxygen octahedra around out-of-plane or in-plane axes, and an\nanti-polar mode. Symmetry-allowed intermode couplings are identified and used\nto elucidate the nature of the observed phase transitions. For the\nminimum-period [1:1] \\pzta\\ superlattice, we identify a sequence of three\ntransitions that occur as the in-plane lattice constant is increased. All four\nof the phases involve substantial oxygen octahedral rotations, and an antipolar\ndistortion is important in the high-tensile-strain phase. Inclusion of these\ndistortions is found to be crucial for an accurate determination of the phase\nboundaries."
    },
    {
        "anchor": "Interstitial bismuth dimers and single atoms as possible centres of\n  broadband near-IR luminescence in bismuth-doped glasses: Absorption, luminescence and Raman spectra of interstitial bismuth atoms,\n$\\mathrm{Bi}^{0}$, and negatively charged dimers, $\\mathrm{Bi}^{2-}$, in\nalumosilicate, germanosilicate, phosphosilicate and phosphogermanate glasses\nnetworks are calculated by time-dependent density functional method. On grounds\nof this calculation an extension of our previously suggested model of broadband\nnear-IR luminescence in bismuth-doped glasses is put forward.",
        "positive": "Predicting the Volumes of Crystals: New crystal structures are frequently derived by performing ionic\nsubstitutions on known crystal structures. These derived structures are then\nused in further experimental analysis, or as the initial guess for structural\noptimization in electronic structure calculations, both of which usually\nrequire a reasonable guess of the lattice parameters. In this work, we propose\ntwo lattice prediction schemes to improve the initial guess of a candidate\ncrystal structure. The first scheme relies on a one-to-one mapping of species\nin the candidate crystal structure to a known crystal structure, while the\nsecond scheme relies on data-mined minimum atom pair distances to predict the\ncrystal volume of the candidate crystal structure and does not require a\nreference structure. We demonstrate that the two schemes can effectively\npredict the volumes within mean absolute errors (MAE) as low as 3.8% and 8.2%.\nWe also discuss the various factors that may impact the performance of the\nschemes. Implementations for both schemes are available in the open-source\npymatgen software."
    },
    {
        "anchor": "Measurement of the local Jahn-Teller distortion in LaMnO_3.006: The atomic pair distribution function (PDF) of stoichiometric LaMnO_3 has\nbeen measured. This has been fit with a structural model to extract the local\nJahn-Teller distortion for an ideal Mn(3+)O_6 octahedron. These results are\ncompared to Rietveld refinements of the same data which give the average\nstructure. Since the local structure is being measured in the PDF there is no\nassumption of long-range orbital order and the real, local, Jahn-Teller\ndistortion is measured directly. We find good agreement both with published\ncrystallographic results and our own Rietveld refinements suggesting that in an\naccurately stoichiometric material there is long range orbital order as\nexpected. The local Jahn-Teller distortion has 2 short, 2 medium and 2 long\nbonds.",
        "positive": "Two-dimensional InSe as a potential thermoelectric material: Thermoelectric properties of monolayer indium selenide (InSe) are\ninvestigated by using Boltzman transport theory and first-principles\ncalculations as a function of Fermi energy and crystal orientation. We find\nthat the maximum power factor of p-type (n-type) monolayer InSe can be as large\nas 0.049 (0.043) W/K$^2$m at 300 K in the armchair direction. The excellent\nthermoelectric performance of monolayer InSe is attributed to both of its\nSeebeck coefficient and electrical conductivity. The large Seebeck coefficient\noriginates from the moderate (about 2 eV) band gap of monolayer InSe as an\nindirect gap semiconductor, while its large electrical conductivity is due to\nits unique two-dimensional density of states (DOS), which consists of an almost\nconstant DOS near the conduction band bottom and a sharp peak near the valence\nband top."
    },
    {
        "anchor": "On probabilistic aspects in the dynamic degradation of ductile materials: Dynamic loadings produce high stress waves leading to the spallation of\nductile materials such as aluminum, copper, magnesium or tantalum. The main\nmechanism used herein to explain the change of the number of cavities with the\nstress rate is nucleation inhibition, as induced by the growth of already\nnucleated cavities. The dependence of the spall strength and critical time with\nthe loading rate is investigated in the framework of a probabilistic model. The\npresent approach, which explains previous experimental findings on the\nstrain-rate dependence of the spall strength, is applied to analyze\nexperimental data on tantalum.",
        "positive": "Efficient calculation of van der Waals dispersion coefficients with\n  time-dependent density functional theory in real time: application to\n  polycyclic aromatic hydrocarbons: The van der Waals dispersion coefficients of a set of polycyclic aromatic\nhydrocarbons, ranging in size from the single-cycle benzene to circumovalene\n(C66H20), are calculated with a real-time propagation approach to\ntime-dependent density functional theory (TDDFT). In the non-retarded regime,\nthe Casimir-Polder integral is employed to obtain C6, once the dynamic\npolarizabilities have been computed at imaginary frequencies with TDDFT. On the\nother hand, the numerical coefficient that characterizes the fully retarded\nregime is obtained from the static polarizabilities. This ab initio strategy\nhas favorable scaling with the size of the system - as demonstrated by the size\nof the reported molecules - and can be easily extended to obtain higher order\nvan der Waals coefficients."
    },
    {
        "anchor": "Hole self-trapping in the Y3Al5O12 and Lu3Al5O12 garnet crystals: The processes of hole localization in the Y3Al5O12 and Lu3Al5O12 single\ncrystals were investigated by electron paramagnetic resonance (EPR) and\nthermally stimulated luminescence (TSL). It was found that holes created by\nx-ray irradiation at 77 K are predominantly self-trapped at regular oxygen ions\nforming O- hole center. This self-trapped hole (STH) center is thermally stable\nto about 100 K in both YAG and LuAG crystals. At higher temperatures, thermally\nliberated holes are retrapped at oxygen ions in the vicinity of an acceptor ion\nsuch as Mg2+ and Al_{Y} or Al_{Lu} antisite ion that leads to increase of the\nthermal stability of the trapped hole to app. 150 K. TSL measurements show two\ncomposite glow peaks in the temperature range of 77 - 280 K, the temperature\npositions of which well correlate with the thermal stability of the O- centers.\nThe hole thermal ionization energy was determined from a numerical fit of the\nTSL peaks within the model of second order kinetics. It is in the range of 0.25\n- 0.26 eV for the O- STH center, and increases to 0.41 - 0.45 eV for O- center\nstabilized by the acceptor. Revealed O- centers can be attributed to O- small\npolarons formed mainly due to the hole stabilization by short-range interaction\nwith the surrounding lattice.",
        "positive": "Melting of graphene: from two to one dimension: The high temperature behaviour of graphene is studied by atomistic\nsimulations based on an accurate interatomic potential for carbon. We find that\nclustering of Stone-Wales defects and formation of octagons are the first steps\nin the process of melting which proceeds via the formation of carbon chains.\nThe molten state forms a three-dimensional network of entangled chains rather\nthan a simple liquid. The melting temperature estimated from the\ntwo-dimensional Lindemann criterion and from extrapolation of our simulation\nfor different heating rates is about 4900 K."
    },
    {
        "anchor": "Berry-phase treatment of the homogeneous electric field perturbation in\n  insulators: A perturbation theory of the static response of insulating crystals to\nhomogeneous electric fields, that combines the modern theory of polarization\n(MTP) with the variation-perturbation framework is developed, at unrestricted\norder of perturbation. First, we address conceptual issues related to the\ndefinition of such a perturbative approach. In particular, in our definition of\nan electric-field-dependent energy functional for periodic systems, the\nposition operator appearing in the perturbation term is replaced by a\nBerry-phase expression, along the lines of the MTP. Moreover, due to the\nunbound nature of the perturbation, a regularization of the Berry-phase\nexpression for the polarization is needed in order to define a\nnumerically-stable variational procedure. Regularization is achieved by means\nof discretization, which can be performed either before or after the\nperturbation expansion. We compare the two possibilities and apply them to a\nmodel tight-binding Hamiltonian. Lowest-order as well as generic formulas are\npresented for the derivatives of the total energy, the normalization condition,\nthe eigenequation, and the Lagrange parameters.",
        "positive": "Phonon-Assisted Lasing in ZnO Microwires at Room Temperature: We report on room temperature phonon-assisted whispering gallery mode (WGM)\nlasing in ZnO microwires. For WGM laser action on the basis of the low gain\nphonon scattering process high quality resonators with sharp corners and smooth\nfacets are prerequisite. Above the excitation threshold power $P_{\\textit{Th}}$\nof typically $100\\,kW/cm^2$, the recombination of free excitons under emission\nof two longitudinal optical phonons provides sufficient gain to overcome all\nlosses in the microresonator and to result in laser oscillation. This threshold\nbehavior is accompanied by a distinct change of the far and near field emission\npatterns, revealing the WGM related nature of the lasing modes. The spectral\nevolution as well as the characteristic behavior of the integrated\nphotoluminescence intensity versus the excitation power unambiguously prove\nlaser operation. Polarization-resolved measurements show that the laser\nemission is linear polarized perpendicular to the microwire axis (TE)."
    },
    {
        "anchor": "Highly Modulated Dual Semimetal and Semiconducting Gamma-GeSe with\n  Strain Engineering: Layered hexagonal Gamma--GeSe, a new polymorph of GeSe synthesized recently,\nshows strikingly high electronic conductivity in its bulk form (even higher\nthan graphite) while semiconducting in the case of monolayer (1L). In this\nwork, by using first-principles calculations, we demonstrate that, different\nfrom its orthorhombic phases of GeSe, the Gamma--GeSe shows a small spatial\nanisotropic dependence and a strikingly thickness-dependent behavior with\ntransition from semimetal (bulk, 0.04 eV) to semiconductor (1L, 0.99 eV), and\nthis dual conducting characteristic realized simply with thickness control in\nGamma-GeSe has not been found in other 2D materials before. The lacking of\nd-orbital allows charge carrier with small effective mass (0.16 m0 for electron\nand 0.23 m0 for hole) which is comparable to phosphorene. Meanwhile, 1L\nGamma--GeSe shows a superior flexibility with Young's modulus of 86.59 N/m,\nonly one-quarter of that of graphene and three-quarters of that of MoS2, and\nPoisson's ratio of 0.26, suggesting a highly flexible lattice. Interestingly,\n1L Gamma-GeSe shows an in-plane isotropic elastic modulus inherent with\nhexagonal symmetry while an anisotropic in-plane effective mass owing to\nshifted valleys around the band edges. We demonstrate the feasibility of strain\nengineering in inducing indirect-direct and semiconductor-metal transitions\nresulting from competing bands at the band edges. Our work shows that the free\n1L Gamma-GeSe shows a strong light absorption (~106 cm-1) and an indirect\nbandgap with rich valleys at band edges, enabling high carrier concentration\nand a low rate of direct electron-hole recombination which would be promising\nfor nanoelectronics and solar cell applications.",
        "positive": "Bonding Configurations and Collective Patterns of Ge Atoms Adsorbed on\n  Si(111)-7x7: We report scanning tunneling microscopy observations of Ge deposited on the\nSi(111)-7x7 surface for a sequence of sub-monolayer coverages. We demonstrate\nthat Ge atoms replace so-called Si adatoms. Initially, the replacements are\nrandom, but distinct patterns emerge and evolve with increasing coverage, till\nsmall islands begin to form. Corner adatom sites in the faulted half unit cells\nare preferred. First-principles density functional calculations find that\nadatom substitution competes energetically with a high-coordination bridge\nsite, but atoms occupying the latter sites are highly mobile. Thus, the\nobserved structures are indeed more thermodynamically stable."
    },
    {
        "anchor": "Predicted Complex Lithium Phases at Terapascal Pressures: We investigate the pressure-temperature ($p$-$T$) phase diagram of elemental\nlithium (Li) up to multiterapascal (TPa) pressures using ab-initio random\nstructure search (AIRSS) and density functional theory (DFT). At zero\ntemperature, beyond the high-pressure $Fd\\bar{3}m$ diamond structure predicted\nin previous studies, we find eleven solid-state phase transitions to structures\nof greatly varying complexity, in addition to two structures that we calculate\nwill become stable with sufficient temperature. The full $p$-$T$ dependence of\nthe phase boundaries are computed within the vibrational harmonic\napproximation, and the solid-liquid melting line is calculated using ab-initio\nmolecular dynamics simulations. Notably, between 39.1 TPa and 55.7 TPa, Li\nadopts an elaborate monoclinic structure with 46 atoms in the primitive unit\ncell, and between 71.9 TPa and $103$ TPa, an incommensurate host-guest phase of\nthe Ba-IV type. We find that Li, hitherto predicted to be an electride at TPa\npressures, abruptly loses its electride character above 16 TPa, reverting back\nto normal metallic behaviour with a corresponding rise in the Fermi-level\nelectronic density of states (eDOS) and broadening of the electronic bands.",
        "positive": "Frictionless motion of diffuse interfaces by sharp phase-field modeling: Diffuse interface descriptions offer many advantages for the modeling of\nmicrostructure evolution. However, the numerical representation of moving\ndiffuse interfaces on discrete numerical grids involves spurious grid friction,\nwhich limits the overall performance of the model in many respects.\nInterestingly, this intricate and detrimental effect can be overcome in Finite\nDifference (FD) and Fast Fourier Transformation (FFT) based implementations by\nemploying the so-called Sharp Phase-Field Method (SPFM). The key idea is to\nrestore the discretization induced broken Translational Invariance (TI) in the\ndiscrete phase-field equation by using analytic properties of the equilibrium\ninterface profile. We proof that this method can indeed eliminate spurious grid\nfriction in the three dimensional space. Focussing on homogeneous driving\nforces, we quantitatively evaluate the impact of spurious grid friction on the\noverall operational performance of different phase-field models. We show that\nthe SPFM provides superior degrees of interface isotropy with respect to energy\nand kinetics. The latter property enables the frictionless motion of\narbitrarily oriented diffuse interfaces on a fixed 3D grid."
    },
    {
        "anchor": "High magnetic field evolution of ferroelectricity in CuCrO2: CuCrO2 offers insights into the different types of spiral magnetic orderings\nthat can form spontaneously due to frustration in triangular-lattice\nantiferromagnets. We explore the magnetic phase diagram up to 65 T along all\nthe principle axes, and also use electric polarization to probe changes in the\nspiral order at high magnetic fields. It is known that at zero magnetic field a\nproper-screw spiral of the Cr S = 3/2 spins forms that in turn induces electric\npolarization with six possible orientations ab-plane. Applied magnetic fields\nin the (hard) ab-plane have been shown to induce a transition to cycloidal\nspiral magnetic order above 5.3 T in those domains that have spins\nperpendicular to the applied magnetic field. We show that the cycloidal order\nremains unchanged all the way up to 65 T, which is one quarter of the\nextrapolated saturation magnetization. On the other hand for magnetic fields\nalong the (easy) c-axis, we observe a transition in the electric polarization\nnear 45 T, and it is followed by a series of steps and/or oscillations in the\nelectric polarization. The data is consistent with the a\nproper-screw-to-cycloidal transition that is pushed from 5.3 to 45 T by\neasy-axis anisotropy, and is in turn followed by stretching of the magnetic\nspiral through commensurate and incommensurate wave vectors. This work also\nhighlights the ability of the magnetically-induced electric polarization to\nprobe complex magnetic orders in regimes of phase space that are difficult to\nreach with neutron diffraction.",
        "positive": "Bichiral structure of feroelectric domain wall driven by\n  flexoelectricity: The influence of flexoelectric coupling on the internal structure of neutral\ndomain walls in tetragonal phase of perovskite ferroelectrics is studied. The\neffect is shown to lower the symmetry of 180-degree walls which are oblique\nwith respect to the cubic crystallographic axes, while {100} and {110} walls\nstay \"untouched\". Being of the Ising type in the absence of the flexoelectric\ninteraction, the oblique domain walls acquire a new polarization component with\na structure qualitatively different from the classical Bloch-wall structure. In\ncontrast to the Bloch-type walls, where the polarization vector draws a helix\non passing from one domain to the other, in the flexoeffect-affected wall, the\npolarization rotates in opposite directions on the two sides of the wall and\npasses through zero in its center. Since the resulting polarization profile is\ninvariant upon inversion with respect to the wall center it does not brake the\nwall symmetry in contrast to the classical Bloch-type walls. The flexoelectric\ncoupling lower the domain wall energy and gives rise to its additional\nanisotropy that is comparable to that conditioned by the elastic anisotropy.\nThe atomic orderof- magnitude estimates shows that the new polarization\ncomponent P2 may be comparable with spontaneous polarization Ps, thus\nsuggesting that, in general, the flexoelectric coupling should be mandatory\nincluded in domain wall simulations in ferroelectrics. Calculations performed\nfor barium titanate yields the maximal value of the P2, which is much smaller\nthan that of the spontaneous polarization. This smallness is attributed to an\nanomalously small value of a component of the \"strain-polarization\"\nelecrostictive tensor in this material."
    },
    {
        "anchor": "Architected Materials for Mechanical Compression: Design via Simulation,\n  Deep Learning, and Experimentation: Architected materials can achieve enhanced properties compared to their plain\ncounterparts. Specific architecting serves as a powerful design lever to\nachieve targeted behavior without changing the base material. Thus, the\nconnection between architected structure and resultant properties remains an\nopen field of great interest to many fields, from aerospace to civil to\nautomotive applications. Here, we focus on properties related to mechanical\ncompression, and design hierarchical honeycomb structures to meet specific\nvalues of stiffness and compressive stress. To do so, we employ a combination\nof techniques in a singular workflow, starting with molecular dynamics\nsimulation of the forward design problem, augmenting with data-driven\nartificial intelligence models to address the inverse design problem, and\nverifying the behavior of de novo structures with experimentation of additively\nmanufactured samples. We thereby demonstrate an approach for architected design\nthat is generalizable to multiple material properties and agnostic to the\nidentity of the base material.",
        "positive": "Mid-infrared Plasmonic Circular Dichroism Generated by Graphene Nanodisk\n  Assemblies: It is very interesting to bring plasmonic circular dichroism spectroscopy to\nthe mid-infrared spectral interval, and there are two reasons for this. This\nspectral interval is very important for thermal bio-imaging and,\nsimultaneously, this spectral range includes vibrational lines of many chiral\nbiomolecules. Here we demonstrate that graphene plasmons indeed offer such\nopportunity. In particular, we show that chiral graphene assemblies consisting\nof a few graphene nanodisks can generate strong circular dichroism (CD) in the\nmid-infrared interval. The CD signal is generated due to the plasmon-plasmon\ncoupling between adjacent nanodisks in the specially designed chiral graphene\nassemblies. Because of the large dimension mismatch between the thickness of a\ngraphene layer and the incoming light's wavelength, three-dimensional\nconfigurations with a total height of a few hundred nanometers are necessary to\nobtain a strong CD signal in the mid-infrared range. The mid-infrared CD\nstrength is mainly governed by the total dimensions (total height and helix\nscaffold radius) of the graphene nanodisk assembly, and by the plasmon-plasmon\ninteraction strength between its constitutive nanodisks. Both positive and\nnegative CD bands can be observed in the graphene assembly array. The frequency\ninterval of the plasmonic CD spectra overlaps with the vibrational modes of\nsome important biomolecules, such as DNA and many different peptides, giving\nrise to the possibility of enhancing the vibrational optical activity of these\nmolecular species by attaching them to the graphene assemblies. Simultaneously\nthe spectral range of chiral mid-infrared plasmons in our structures appears\nnear the typical wavelength of the human-body thermal radiation and, therefore,\nour chiral metastructures can be potentially utilized as optical components in\nthermal imaging devices."
    },
    {
        "anchor": "Linear complexions: Metastable phase formation and coexistence at\n  dislocations: The unique three-phase coexistence of metastable B2-FeNi with stable L10-FeNi\nand L12-FeNi3 is discovered near edge dislocations in body-centered cubic Fe-Ni\nalloys using atomistic simulations. Stable nanoscale precipitate arrays, formed\nalong the compression side of dislocation lines and defined as linear\ncomplexions, were observed for a wide range of compositions and temperatures.\nBy analyzing the thermodynamics associated with these phase transitions, we are\nable to explain the metastable phase formation and coexistence, in the process\ndefining new research avenues for theoretical and experimental investigations.",
        "positive": "Green's Function Measurements of Force Transmission in 2D Granular\n  Materials: We describe experiments that probe the response to a point force of 2D\ngranular systems under a variety of conditions. Using photoelastic particles to\ndetermine forces at the grain scale, we experimentally show that disorder,\npacking structure, friction and texture significantly affect the average force\nresponse in granular systems. For packings with weak disorder, the mean forces\npropagate primarily along lattice directions. The width of the response along\nthese preferred directions grows with depth, increasingly so as the disorder of\nthe system grows. Also, as the disorder increases, the two propagation\ndirections of the mean force merge into a single direction. The response\nfunction for the mean force in the most strongly disordered system is\nquantitatively consistent with an elastic description for forces applied nearly\nnormally to a surface. These observations are consistent with recent\npredictions of Bouchaud et al. and with the anisotropic elasticity models of\nGoldenberg and Goldhirsch. At this time, it is not possible to distinguish\nbetween these two models. The data do not support a diffusive picture, as in\nthe q-model. This system with shear deformation is characterized by stress\nchains that are strongly oriented along an angle of 45 degrees, corresponding\nto the compressive direction of the shear deformation. In this case, the\nspatial correlation function for force has a range of only one particle size in\nthe direction transverse to the chains, and varies as a power law in the\ndirection of the chains, with an exponent of -0.81. The response to forces is\nstrongest along the direction of the force chains, as expected. Forces applied\nin other directions are effectively refocused towards the strong force chain\ndirection."
    },
    {
        "anchor": "Electronic properties and quasi-particle model of monolayer\n  MoSi$_2$N$_4$: By a combined study with first-principles calculations and symmetry analysis,\nwe theoretically investigate the electronic properties of monolayer\nMoSi$_2$N$_4$. While the spin-orbital coupling results in bands splitting, the\nhorizontal mirror symmetry locks the spin polarization along z-direction. In\naddition, a three-band tight-binding model is constructed to describe the\nlow-energy quasi-particle states of monolayer MoSi$_2$N$_4$, which can be\ngeneralized to strained MoSi$_2$N$_4$ and its derivatives. The calculations\nusing the tight-binding model show an undamped $\\sqrt{q}$-dependent plasmon\nmode that agrees well with the results of first-principles calculations. Our\nmodel can be extended to be suitable for future theoretical and numerical\nstudies of low-energy properties in MoSi$_2$N$_4$ family materials.\nFurthermore, the study of electronic properties of monolayer MoSi$_2$N$_4$\npaves a way for its applications in spintronics and plasmonics.",
        "positive": "Magnetotransport in Sr3PbO antiperovskite with three-dimensional massive\n  Dirac electrons: Novel topological phenomena are anticipated for three-dimensional (3D) Dirac\nelectrons. The magnetotransport properties of cubic ${\\rm Sr_{3}PbO}$\nantiperovskite, theoretically proposed to be a 3D massive Dirac electron\nsystem, are studied. The measurements of Shubnikov-de Haas oscillations and\nHall resistivity indicate the presence of a low density ($\\sim 1 \\times\n10^{18}$ ${\\rm cm^{-3}}$) of holes with an extremely small cyclotron mass of\n0.01-0.06$m_{e}$. The magnetoresistance $\\Delta\\rho_{xx}(B)$ is linear in\nmagnetic field $B$ with the magnitude independent of temperature. These results\nare fully consistent with the presence of 3D massive Dirac electrons in ${\\rm\nSr_{3}PbO}$. The chemical flexibility of the antiperovskites and our findings\nin the family member, ${\\rm Sr_{3}PbO}$, point to their potential as a model\nsystem in which to explore exotic topological phases."
    },
    {
        "anchor": "Interfacial spin glass mediated unusual spontaneous exchange bias effect\n  in epitaxial self-assembled La0.7Sr0.3MnO3:NiO nanocomposite thin films: Zero field cooled spontaneous exchange bias (SEB) is observed in epitaxial\nLa0.7Sr0.3MnO3 (LSMO):NiO self-assembled nanocomposite thin films grown on\n(001) SrTiO3 single crystal substrate by pulsed laser deposition. SEB is\ndisplayed by the novel asymmetry in the hysteresis loop of the composite film\nalong with the field cooled conventional exchange bias (CEB) effect. The\ntraining effect shows that exchange bias relaxation is disorder mediated. It is\nrevealed from DC magnetization results that such nanocomposite film divulges\nspin glass like behaviour, which is arising due to competing ferromagnetic and\nantiferromagnetic inteactions at the assorted interfaces of ferromagnetic LSMO\nand antiferromagnetic NiO. Also corroborated by x-ray magnetic circular\ndichroism (XMCD) measurements, we conclude that SEB is mainly originating due\nto ferromagnetic coupling of unstable interfacial antiferromagnetic spin due to\nNiO with the ferromagnetic LSMO at the disordered interface. These results of\nself-assembled thin films provide a useful input to realize and understand\nmicroscopic origin of SEB for device application.",
        "positive": "Magnetic, electronic and vibrational properties of metal and fluorinated\n  metal phthalocyanines: The magnetic and electronic properties of metal phthalocyanines (MPc) and\nfluorinated metal phthalocyanines (F$_{16}$MPc) are studied by means of spin\ndensity functional theory (SDFT). Several metals (M) such as Ca, all first\nd-row transition metals and Ag are investigated. By considering different open\nshell transition metals it is possible to tune the electronic properties of\nMPc, in particular the electronic molecular gap and total magnetic moment.\nBesides assigning the structural and electronic properties of MPc and\nF$_{16}$MPc, the vibrational modes analysis of the ScPc\\textendash ZnPc series\nhave been studied and correlated to experimental measurements when available."
    },
    {
        "anchor": "Skyrmion Alignment and Pinning Effects in a Disordered Multi-Phase\n  Skyrmion Material Co8Zn8Mn4: Underlying disorder in skyrmion materials may both inhibit and facilitate\nskyrmion reorientations and changes in topology. The identification of these\ndisorder-induced topologically active regimes is critical to realizing robust\nskyrmion spintronic implementations, yet few studies exist for disordered bulk\nsamples. Here, we employ small-angle neutron scattering (SANS) and\nmicromagnetic simulations to examine the influence of skyrmion order on\nskyrmion lattice formation, transition, and reorientation dynamics across the\nphase space of a disordered polycrystalline Co$_{8}$Zn$_{8}$Mn$_{4}$ bulk\nsample. Our measurements reveal a new disordered-to-ordered skyrmion square\nlattice transition pathway characterized by the novel promotion of four-fold\norder in SANS and accompanied by a change in topology of the system, reinforced\nthrough micromagnetic simulations. Pinning responses are observed to dominate\nskyrmion dynamics in the metastable triangular lattice phase, enhancing\nskyrmion stabilization through a remarkable and previously undetected skyrmion\nmemory effect which reproduces previous ordering processes and persists in zero\nfield. These results uncover the cooperative interplay of anisotropy and\ndisorder in skyrmion formation and restructuring dynamics, establishing new\ntunable pathways for skyrmion manipulation.",
        "positive": "Isothermal and Adiabatic Elastic Tensors: The adiabatic elastic modulus is often useful in the high frequency response\nof materials. Unfortunately, it can be much more difficult to directly measure\nthe adiabatic elastic modulus of material than the isothermal elastic modulus.\nWe derive the relationship between the adiabatic and isothermal elastic tensors\nfrom the first law of thermodynamics."
    },
    {
        "anchor": "Enhancement of sound in chirped sonic crystals: We propose and experimentally demonstrate a novel mechanism of sound wave\nconcentration based on soft reflections in chirped sonic crystals. The reported\ncontrolled field enhancement occurs at around particular (bright) planes in the\ncrystal, and is related to a progressive slowing down of the sound wave as it\npropagates along the material. At these bright planes, a substantial\nconcentration of the energy (with a local increase up to 20 times) was obtained\nfor a linear chirp and for frequencies around the first band gap. A simple\ncouple mode theory is proposed, that interprets and estimates the observed\neffects. The results are obtained for the case of sound waves and sonic\ncrystals, however they are extendable to other type of waves in modulated host\nmatter.",
        "positive": "Universal valence-band picture of the ferromagnetic semiconductor GaMnAs: The origin of ferromagnetism in the prototype ferromagnetic semiconductor\nGaMnAs is still controversial due to the insufficient understanding of its band\nstructure and Fermi level position. Here, we show the universal valence-band\n(VB) picture of GaMnAs obtained by resonant tunneling spectroscopy for a\nvariety of surface GaMnAs layers with the Mn concentrations from 6 to 15% and\nthe Curie temperatures from 71 to 154 K. We find that the Fermi level exists in\nthe bandgap, and that the VB structure of GaAs is almost perfectly maintained\nin all the GaMnAs samples, i.e. VB is not merged with the impurity band.\nFurthermore, the p-d exchange splitting of VB is found to be quite small (only\nseveral meV) even in GaMnAs with a high Curie temperature (154 K). These\nresults indicate that the VB structure of GaMnAs is quite insensitive to the Mn\ndoping."
    },
    {
        "anchor": "Domain structure in CoFeB thin films with perpendicular magnetic\n  anisotropy: Domain structures in CoFeB-MgO thin films with a perpendicular easy\nmagnetization axis were observed by magneto-optic Kerr-effect microscopy at\nvarious temperatures. The domain wall surface energy was obtained by analyzing\nthe spatial period of the stripe domains and fitting established domain models\nto the period. In combination with SQUID measurements of magnetization and\nanisotropy energy, this leads to an estimate of the exchange stiffness and\ndomain wall width in these films. These parameters are essential for\ndetermining whether domain walls will form in patterned structures and devices\nmade of such materials.",
        "positive": "Unusual polymerization in the Li4C60 fulleride: Li4C60, one of the best representatives of lithium intercalated fullerides,\nfeatures a novel type of 2D polymerization. Extensive investigations, including\nlaboratory x-ray and synchrotron radiation diffraction, 13C NMR, MAS and Raman\nspectroscopy, show a monoclinic I2/m structure, characterized by chains of\n[2+2]-cycloaddicted fullerenes, sideways connected by single C-C bonds. This\nleads to the formation of polymeric layers, whose insulating nature, deduced\nfrom the NMR and Raman spectra, denotes the complete localization of the\nelectrons involved in the covalent bonds."
    },
    {
        "anchor": "Monitoring near-surface depth profile of residual stress in weakly\n  anisotropic media by Rayleigh-wave dispersion: Herein we study the inverse problem on inferring depth profile of\nnear-surface residual stress in a weakly anisotropic medium by boundary\nmeasurement of Rayleigh-wave dispersion if all other relevant material\nparameters of the elastic medium are known. Our solution of this inverse\nproblem is based on a recently developed algorithm by which each term of a\nhigh-frequency asymptotic formula for dispersion relations can be computed for\nRayleigh waves that propagate in various directions along the free surface of a\nvertically-inhomogeneous, prestressed, and weakly anisotropic half-space. As a\nprime example of possible applications we focus on a thick-plate sample of AA\n7075-T651 aluminum alloy, which has one face treated by low plasticity\nburnishing (LPB) that induced a depth-dependent prestress at and immediately\nbeneath the treated surface. We model the sample as a prestressed,\nweakly-textured orthorhombic aggregate of cubic crystallites and assume that by\nnondestructive and/or destructive measurements we have ascertained everything\nabout the sample, including the LPB-induced prestress, before it is put into\nservice. Under the supposition that the prestress be partially relaxed but\nother material parameters remain unchanged after the sample undergoes a period\nof service, we examine the possibility of inferring the depth profile of the\npartially relaxed stress by boundary measurement of Rayleigh-wave dispersion.",
        "positive": "Addressing the lattice stability puzzle in the computational\n  determination of intermetallic phase diagrams: The evaluation of phase stabilities of unstable elemental phases is a\nlong-standing problem in the computational assessment of phase diagrams. Here\nwe tackle this problem by explicitly calculating phase diagrams of\nintermetallic systems where its effect should be most conspicuous, binary\nsystems of titanium with bcc transition metals (Mo, Nb, Ta and V). Two types of\nphase diagrams are constructed: one based on the lattice stabilities extracted\nfrom empirical data, and the other using the lattice stabilities computed from\nfirst principles. It is shown that the phase diagrams obtained using the\nempirical values contain clear contradictions with the experimental phase\ndiagrams at the well known limits of low or high temperatures. Realistic phase\ndiagrams, with a good agreement with the experimental observations, are\nachieved only when the computed lattice stability values are used. At\nintermediate temperatures, the computed phase diagrams resolve the controversy\nregarding the shape of the solvus in these systems, predicting a complex\nstructure with a eutectoid transition and a miscibility gap between two bcc\nphases."
    },
    {
        "anchor": "Predicting polarization and nonlinear dielectric response of arbitrary\n  perovskite superlattice sequences: We carry out first-principles calculations of the nonlinear dielectric\nresponse of short-period ferroelectric superlattices. We compute and store not\nonly the total polarization, but also the Wannier-based polarizations of\nindividual atomic layers, as a function of electric displacement field, and use\nthis information to construct a model capable of predicting the nonlinear\ndielectric response of an arbitrary superlattice sequence. We demonstrate the\nsuccessful application of our approach to superlattices composed of SrTiO$_3$,\nCaTiO$_3$, and BaTiO$_3$ layers.",
        "positive": "Linear magnetization dependence and large intrinsic anomalous Hall\n  effect in Fe78Si9B13 metallic glasses: The origin of anomalous Hall effect (AHE) in ferromagnetic metallic glasses\n(MGs) is not yet understood completely. Here, the AHE is explored in Fe78Si9B13\nMGs. We find the behavior of resistivity at low temperature seems to be more\nlikely due to structure effect rather than Kondo-type effect. More importantly,\nwe firstly find the primitive experiment anomalous Hall conductivity\n({\\sigma}AH) without separation of extrinsic contribution has a linear\nmagnetization (Mz) dependence when temperature is changing, which is another\nfeature of intrinsic mechanism and indicates intrinsic contribution is\ndominated. Furthermore, the {\\sigma}AH normalized by Mz is independent of\nlongitudinal conductivity ({\\sigma}xx), which shows the characteristic of\ndissipationless intrinsic mechanism. We suggest the intrinsic contribution can\nbe understood from the density of Berry curvature integrated over occupied\nenergies proposed for aperiodic materials recently, and the linear\nmagnetization dependence can be understood qualitatively from the fluctuations\nof spin orientation and the proportional relationship between Berry curvature\nand magnetization. Moreover, based on the recent theory report of topological\namorphous metals, we make a prediction that the large intrinsic {\\sigma}AH (616\nS/cm) in Fe78Si9B13 MGs implies some topological properties of MGs waiting for\nfurther discovery."
    },
    {
        "anchor": "Icosahedral Ti-Zr-Ni: A groundstate quasicrystal?: The first complete ab initio zero-temperature ternary phase diagram is\nconstructed from the calculated energies of the elemental, binary and ternary\nTi-Zr-Ni phases; for this, the icosahedral i-TiZrNi quasicrystal phase is\napproximated by periodic structures of up to 123 atoms/unit cell, based on a\ndecorated-tiling model. The approximant structures containing the 45-atom\nBergman cluster were nearly degenerate, and stable against the competing binary\nphases. It is speculated that i-TiZrNi may be a ground state quasicrystal, as\nit is experimentally the low-temperature phase for its composition.",
        "positive": "Spin relaxation in an InAs quantum dot in the presence of terahertz\n  driving fields: The spin relaxation in a 1D InAs quantum dot with the Rashba spin-orbit\ncoupling under driving THz magnetic fields is investigated by developing the\nkinetic equation with the help of the Floquet-Markov theory, which is\ngeneralized to the system with the spin-orbit coupling, to include both the\nstrong driving field and the electron-phonon scattering. The spin relaxation\ntime can be effectively prolonged or shortened by the terahertz magnetic field\ndepending on the frequency and strength of the terahertz magnetic field. The\neffect can be understood as the sideband-modulated spin-phonon scattering. This\noffers an additional way to manipulate the spin relaxation time."
    },
    {
        "anchor": "Analysis of lattice locations of deuterium in tungsten and its\n  application for predicting deuterium trapping conditions: Retention of hydrogen isotopes (protium, deuterium and tritium) in tungsten\nis one of the most severe issues in design of fusion power plants, since\nsignificant trapping of tritium may cause exceeding radioactivity safety limits\nin future reactors. Hydrogen isotopes in tungsten can be detected using the\nnuclear reaction analysis method in channeling mode (NRA/C). However, the\ninformation hidden within the experimental spectra is subject to\ninterpretation. In this work, we propose the methodology to interpret the\nresponse of the experimental NRA/C spectra to the specific lattice locations of\ndeuterium by simulations of the NRA/C spectra from atomic structures of\ndeuterium lattice locations as obtained from the first principles calculations.\nWe show that trapping conditions, i.e., states of local crystal structures\nretaining deuterium, affect the lattice locations of deuterium and the change\nof lattice locations can be detected by ion channeling method. By analyzing the\nexperimental data, we are able to determine specific information on the\ndeuterium trapping conditions, including the number of deuterium atoms trapped\nby one vacancy as well as the presence of impurity atoms along with deuterium\nin vacancies.",
        "positive": "Domains and ferroelectric switching pathways in Ca$_3$Ti$_2$O$_7$ from\n  first principles: Hybrid improper ferroelectricity, where an electrical polarization can be\ninduced via a trilinear coupling to two non-polar structural distortions of\ndifferent symmetry, has recently been experimentally demonstrated for the first\ntime in the $n$=2 Ruddlesden-Popper compound Ca$_3$Ti$_2$O$_7$. In this paper\nwe use group theoretic methods and first-principles calculations to identify\npossible ferroelectric switching pathways in Ca$_3$Ti$_2$O$_7$. We identify\nlow-energy paths that reverse the polarization direction by switching via an\northorhombic twin domain, or via an antipolar structure. We also introduce a\nchemically intuitive set of local order parameters to give insight into how\nthese paths are relevant to switching nucleated at domain walls. Our findings\nsuggest that switching may proceed via more than one mechanism in this\nmaterial."
    },
    {
        "anchor": "Exploring the nanoscale origin of performance enhancement in\n  Li$_{1.1}$Ni$_{0.35}$Mn$_{0.55}$O$_2$ batteries due to chemical doping: Despite significant potential as energy storage materials for electric\nvehicles due to their combination of high energy density per unit cost and\nreduced environmental and ethical concerns, Co-free lithium ion batteries based\noff layered Mn oxides presently lack the longevity and stability of their\nCo-containing counterparts. Here, we demonstrate a reduction in this\nperformance gap via chemical doping, with Li$_{1.1}$Ni$_{0.35}$Mn$_{0.55}$O$_2$\nachieving an initial discharge capacity of 159 mAhg$^{-1}$ at C/3 rate and a\ncorresponding capacity retention of 94.3% after 150 cycles. We subsequently\nexplore the nanoscale origins of this improvement through a combination of\nadvanced diffraction, spectroscopy, and electron microscopy techniques, finding\nthat optimized doping profiles lead to an improved structural and chemical\ncompatibility between the two constituent sub-phases that characterize the\nlayered Mn oxide system, resulting in the formation of unobstructed lithium ion\npathways between them. We also directly observe a structural stabilization\neffect of the host compound near the surface using aberration corrected\nscanning transmission electron microscopy and integrated differential phase\ncontrast imaging.",
        "positive": "Ferromagnetic semiconductors: The current status and prospects of research on ferromagnetism in\nsemiconductors are reviewed. The question of the origin of ferromagnetism in\neuropium chalcogenides, chromium spinels and, particularly, in diluted magnetic\nsemiconductors is addressed. The nature of electronic states derived from 3d of\nmagnetic impurities is discussed in some details. Results of a quantitative\ncomparison between experimental and theoretical results, notably for Mn-based\nIII-V and II-VI compounds, are presented. This comparison demonstrates that the\ncurrent theory of the exchange interactions mediated by holes in the valence\nband describes correctly the values of Curie temperatures T_C magnetic\nanisotropy, domain structure, and magnetic circular dichroism. On this basis,\nchemical trends are examined and show to lead to the prediction of\nsemiconductor systems with T_C that may exceed room temperature, an expectation\nthat are being confirmed by recent findings. Results for materials containing\nmagnetic ions other than Mn are also presented emphasizing that the double\nexchange involving hoping through d states may operate in those systems."
    },
    {
        "anchor": "Band nesting and the optical response of two-dimensional semiconducting\n  transition metal dichalcogenides: We have studied the optical conductivity of two-dimensional (2D)\nsemiconducting transition metal dichalcogenides (STMDC) using ab-initio density\nfunctional theory (DFT). We find that this class of materials presents large\noptical response due to the phenomenon of band nesting. The tendency towards\nband nesting is enhanced by the presence of van Hove singularities in the band\nstructure of these materials. Given that 2D crystals are atomically thin and\nnaturally transparent, our results show that it is possible to have strong\nphoton-electron interactions even in 2D",
        "positive": "Thermal properties of graphene under tensile stress: Thermal properties of graphene display peculiar characteristics associated to\nthe two-dimensional nature of this crystalline membrane. These properties can\nbe changed and tuned in the presence of applied stresses, both tensile and\ncompressive. Here we study graphene monolayers under tensile stress by using\npath-integral molecular dynamics (PIMD) simulations, which allows one to take\ninto account quantization of vibrational modes and analyze the effect of\nanharmonicity on physical observables. The influence of the elastic energy due\nto strain in the crystalline membrane is studied for increasing tensile stress\nand for rising temperature (thermal expansion). We analyze the internal energy,\nenthalpy, and specific heat of graphene, and compare the results obtained from\nPIMD simulations with those given by a harmonic approximation for the\nvibrational modes. This approximation turns out to be precise at low\ntemperatures, and deteriorates as temperature and pressure are increased. At\nlow temperature the specific heat changes as $c_p \\sim T$ for stress-free\ngraphene, and evolves to a dependence $c_p \\sim T^2$ as the tensile stress is\nincreased. Structural and thermodynamic properties display nonnegligible\nquantum effects, even at temperatures higher than 300~K. Moreover, differences\nin the behavior of the in-plane and real areas of graphene are discussed, along\nwith their associated properties. These differences show up clearly in the\ncorresponding compressibility and thermal expansion coefficient."
    },
    {
        "anchor": "Molecular Autonomous Pathfinder using Deep Reinforcement Learning: Diffusion in solids is a slow process that dictates rate-limiting processes\nin key chemical reactions. Unlike crystalline solids that offer well-defined\ndiffusion pathways, the lack of similar structural motifs in amorphous or\nglassy materials poses a great scientific challenge in estimating slow\ndiffusion time. To tackle this problem, we have developed an AI-guided\nlong-time atomistic simulation approach: Molecular Autonomous Pathfinder (MAP)\nframework based on Deep Reinforcement Learning (RL), where RL agent is trained\nto uncover energy efficient diffusion pathways. We employ Deep Q-Network\narchitecture with distributed prioritized replay buffer enabling fully online\nagent training with accelerated experience sampling by an ensemble of\nasynchronous agents. After training, the agents provide atomistic\nconfigurations of diffusion pathways with their energy profile. We use a\npiecewise Nudged Elastic Band to refine the energy profile of the obtained\npathway and corresponding diffusion time on the basis of transition state\ntheory. With MAP, we have successfully identified atomistic mechanisms along\nmolecular diffusion pathways in amorphous silica, with time scales comparable\nto experiments.",
        "positive": "Phonon Universal Transmission Fluctuations and Localization in\n  Semiconductor Superlattices with a Controlled Degree of Order: We study both analytically and numerically phonon transmission fluctuations\nand localization in partially ordered superlattices with correlations among\nneighboring layers. In order to generate a sequence of layers with a varying\ndegree of order we employ a model proposed by Hendricks and Teller as well as\npartially ordered versions of deterministic aperiodic superlattices. By\nchanging a parameter measuring the correlation among adjacent layers, the\nHendricks- Teller superlattice exhibits a transition from periodic ordering,\nwith alterna- ting layers, to the phase separated opposite limit; including\nmany intermediate arrangements and the completely random case. In the partially\nordered versions of deterministic superlattices, there is short-range order\n(among any $N$ conse- cutive layers) and long range disorder, as in the N-state\nMarkov chains. The average and fluctuations in the transmission, the\nbackscattering rate, and the localization length in these multilayered systems\nare calculated based on the superlattice structure factors we derive\nanalytically. The standard deviation of the transmission versus the average\ntransmission lies on a {\\it universal\\/} curve irrespective of the specific\ntype of disorder of the SL. We illustrate these general results by applying\nthem to several GaAs-AlAs superlattices for the proposed experimental\nobservation of phonon universal transmission fluctuations."
    },
    {
        "anchor": "The influence of substrate temperature on growth of para-sexiphenyl thin\n  films on Ir{111} supported graphene studied by LEEM: The growth of para-sexiphenyl (6P) thin films as a function of substrate\ntemperature on Ir{111} supported graphene flakes has been studied in real-time\nwith Low Energy Electron Microscopy (LEEM). Micro Low Energy Electron\nDiffraction (\\mu LEED) has been used to determine the structure of the\ndifferent 6P features formed on the surface. We observe the nucleation and\ngrowth of a wetting layer consisting of lying molecules in the initial stages\nof growth. Graphene defects -- wrinkles -- are found to be preferential sites\nfor the nucleation of the wetting layer and of the 6P needles that grow on top\nof the wetting layer in the later stages of deposition. The molecular structure\nof the wetting layer and needles is found to be similar. As a result, only a\nlimited number of growth directions are observed for the needles. In contrast,\non the bare Ir{111} surface 6P molecules assume an upright orientation. The\nformation of ramified islands is observed on the bare Ir{111} surface at 320 K\nand 352 K, whereas at 405 K the formation of a continuous layer of upright\nstanding molecules growing in a step flow like manner is observed.",
        "positive": "Complex magnetism of the two-dimensional antiferromagnetic Ge2F: from a\n  N\u00e9el spin-texture to a potential antiferromagnetic skyrmion: Based on density functional theory combined with low-energy models, we\nexplore the magnetic properties of a hybrid atomic-thick two-dimensional (2D)\nmaterial made of Germanene doped with fluorine atoms in a half-fluorinated\nconfiguration (Ge2F). The Fluorine atoms are highly electronegative, which\ninduce magnetism and break inversion symmetry, triggering thereby a finite and\nstrong Dzyaloshinskii-Moriya interaction (DMI). The magnetic exchange\ninteractions is of antiferromagnetic nature among the first, second and third\nneighbors, which leads to magnetic frustration. The N\\'eel state is found to be\nthe most stable state, with magnetic moments lying in the surface plane. This\nresults from the out-of-plane component of the DMI vector, which seems to\ninduce an effective in-plane magnetic anisotropy. Upon application of a\nmagnetic field, spin-spirals and antiferromagnetic skyrmions can be stabilized.\nWe conjecture that this can be realized via magnetic exchange fields induced by\na magnetic substrate. To complete our characterization, we computed the\nspin-wave excitations and the resulting spectra, which could be probed via\nelectron energy loss spectroscopy, magneto-Raman spectroscopy or scanning\ntunneling spectroscopy."
    },
    {
        "anchor": "Surface plasmon polaritons and surface phonon polaritons on metallic and\n  semiconducting spheres: Exact and semiclassical descriptions: We study the interaction of an electromagnetic field with a non-absorbing or\nabsorbing dispersive sphere in the framework of complex angular momentum\ntechniques. We assume that the dielectric function of the sphere presents a\nDrude-like behavior or an ionic crystal behavior modelling metallic and\nsemiconducting materials. We more particularly emphasize and interpret the\nmodifications induced in the resonance spectrum by absorption. We prove that\n\"resonant surface polariton modes\" are generated by a unique surface wave,\ni.e., a surface (plasmon or phonon) polariton, propagating close to the sphere\nsurface. This surface polariton corresponds to a particular Regge pole of the\nelectric part (TM) of the S matrix of the sphere. From the associated Regge\ntrajectory we can construct semiclassically the spectrum of the complex\nfrequencies of the resonant surface polariton modes which can be considered as\nBreit-Wigner-type resonances. Furthermore, by taking into account the Stokes\nphenomenon, we derive an asymptotic expression for the position in the complex\nangular momentum plane of the surface polariton Regge pole. We then describe\nsemiclassically the surface polariton and provide analytical expressions for\nits dispersion relation and its damping in the non-absorbing and absorbing\ncases. In these analytic expressions, we more particularly exhibit\nwell-isolated terms directly linked to absorption. Finally, we explain why the\nphoton-sphere system can be considered as an artificial atom (a ``plasmonic\natom\" or \"phononic atom\") and we briefly discuss the implication of our results\nin the context of the Casimir effect.",
        "positive": "In-situ High Pressure Nuclear Magnetic Resonance Crystallography: Our recent developments in in-situ nuclear magnetic resonance (NMR)\nspectroscopy under extreme conditions led to the observation of a wide variety\nof physical phenomena not accessible with standard high pressure experimental\nprobes. However, inherent di- or quadrupolar line broadening in diamond anvil\ncell (DAC) based NMR experiments often limit detailed investigations of local\natomic structures, especially if different phases or local environments are\ncoexisting. Here, we present our progress in the development of high resolution\nNMR experiments in DACs using one and two-dimensional homonuclear decoupling\nexperiments at pressures up to the Mbar regime. Using this technique, spectral\nresolutions in the order of 1 ppm and below have been achieved, enabling high\npressure structural analysis. Several examples will demonstrate the wide\napplicability of this method for extreme conditions research."
    },
    {
        "anchor": "Melanin Made by Dopamine Oxidation: Thin Films and Interactions with\n  Polyelectrolyte Multilayers: The spontaneous oxidation of dopamine in slightly alkaline solutions was\ninvestigated on the basis of the work of Lee and others [Science, 318:426-430,\n2007], and the reaction product was identified as dopamine-melanin. The ability\nof melanin to covalently bind amine functional groups was confirmed by\nquantification of the corresponding binding sites on dopamine-melanin\naggregates. Furthermore it is possible to redissolve dopamine-melanin\naggregates in strongly alkaline solutions. The obtained small melanin grains\nwere used to build layer-by-layer deposits with poly(diallyldimethylammonium).\n  Different methods of dopamine oxidation to grow melanin films at\nsolid--liquid interfaces were developed. All examined methods lead to\ncontinuous dopamine-melanin films with very similar surface morphologies. The\ndopamine-melanin films become impermeable to electrochemical probes at a\nthickness in the 10 nm range. In this context a higher permeability for\npositively charged and neutral probes than for negatively charged ones was\nconfirmed for one preparation method.\n  The adsorption of proteins on dopamine-melanin coatings was explained as\ncombination of electrostatic and strong, most probably covalent, interactions.\nTo obtain this explanation, the zeta-potential of dopamine-melanin deposits has\nbeen measured as a function of pH.\n  The formation of melanin by dopamine oxidation in layer-by-layer films of\npoly(L-lysine) (PLL) and hyaluronate (HA) was studied: Melanin is able to\nhomogeneously fill $(\\text{PLL-HA})_n$ films and the obtained\npolyelectrolyte-melanin composites can be detached from their substrate as\nfree-standing membranes prepared by a biomimetic method in mild conditions.",
        "positive": "GdBO$_3$ and YBO$_3$ Nanocrystals under Compression: High-pressure X-ray diffraction studies on nanocrystals of the\npseudo-vaterite-type borates GdBO$_3$ and YBO$_3$ are herein reported up to\n17.4(2) and 13.4(2) GPa respectively. The subsequent determination of the\nroom-temperature pressure-volume equations of state is presented and discussed\nin the context of contemporary publications which contradict the findings of\nthis work. In particular, the isothermal bulk moduli of GdBO$_3$ and YBO$_3$\nare found to be 170(13) and 163(13) GPa respectively, almost 50% smaller than\nrecent findings. Our experimental results provide an accurate revision of the\nhigh-pressure compressibility behaviour of GdBO$_3$ and YBO$_3$ which is\nconsistent with the known systematics in isomorphic borates and previous ab\ninitio calculations. Finally we discuss how experimental/analytical errors\ncould have led to unreliable conclusions reported elsewhere."
    },
    {
        "anchor": "Light induced stress and work in photomechanical materials: Increasingly important photomechanical materials produce stress and\nmechanical work when illuminated. We propose experimentally accessible\nperformance metrics for photostress and photowork, enabling comparison of\nmaterials performance. We relate these metrics to material properties,\nproviding a framework for the design and optimization of photomechanical\nmaterials.",
        "positive": "Spin Manipulation by Creation of Single-Molecule Radical Cations: All-trans-retinoic acid (ReA), a closed-shell organic molecule comprising\nonly C, H, and O atoms, is investigated on a Au(111) substrate using scanning\ntunneling microscopy and spectroscopy. In dense arrays single ReA molecules are\nswitched to a number of states, three of which carry a localized spin as\nevidenced by conductance spectroscopy in high magnetic fields. The spin of a\nsingle molecule may be reversibly switched on and off without affecting its\nneighbors. We suggest that ReA on Au is readily converted to a radical by the\nabstraction of an electron."
    },
    {
        "anchor": "Antimony doped Tin Oxide/Polyethylenimine Electron Selective Contact for\n  reliable and light soaking-free high Performance Inverted Organic Solar Cells: We have demonstrated a high-performance low temperature solution processed\nelectron selective contact consisting of 10 at% antimony doped tin oxide (ATO)\nand the neutral polymer polyethylenimine (PEI). Inverted organic photovoltaics\n(OPVs) utilizing ATO/PEI as electron selective contact exhibited high power\nconversion efficiencies for both the reference P3HT: PCBM and the non-fullerene\nbased P3HT- IDTBR active layer OPV material systems. Importantly it is shown\nthat the proposed ATO/PEI carrier selective contact provides light soaking-free\ninverted OPVs. Furthermore, by increasing the thickness of ATO layer from 40 to\n120 nm the power conversion efficiency of the corresponding inverted OPVs\nremain unaffected a parameter which indicates the potential of the proposed\nATO/PEI carrier selective contact for high performance light-soaking-free and\nreliable roll-to-roll printing solutions processed inverted OPVs.",
        "positive": "Polymer informatics at-scale with multitask graph neural networks: Artificial intelligence-based methods are becoming increasingly effective at\nscreening libraries of polymers down to a selection that is manageable for\nexperimental inquiry. The vast majority of presently adopted approaches for\npolymer screening rely on handcrafted chemostructural features extracted from\npolymer repeat units -- a burdensome task as polymer libraries, which\napproximate the polymer chemical search space, progressively grow over time.\nHere, we demonstrate that directly \"machine-learning\" important features from a\npolymer repeat unit is a cheap and viable alternative to extracting expensive\nfeatures by hand. Our approach -- based on graph neural networks, multitask\nlearning, and other advanced deep learning techniques -- speeds up feature\nextraction by one to two orders of magnitude relative to presently adopted\nhandcrafted methods without compromising model accuracy for a variety of\npolymer property prediction tasks. We anticipate that our approach, which\nunlocks the screening of truly massive polymer libraries at scale, will enable\nmore sophisticated and large scale screening technologies in the field of\npolymer informatics."
    },
    {
        "anchor": "Ground-state polariton condensation in 2D-GaAs semiconductor\n  microcavities: We observe ground-state polariton condensation in a two dimensional GaAs/AlAs\nsemiconductor microcavity under non resonant pulsed optical excitation. We\nresolve the formation of a polariton condensate by studying the spatial,\nangular, coherence, energy and transient dynamics of polariton\nphotoluminescence. For high excitation densities we also observe a transition\nfrom the weak- to the strong-coupling regime in the time-domain and resolve the\nbuild-up of a coherent polariton state.",
        "positive": "Physics Guided Deep Learning for Generative Design of Crystal Materials\n  with Symmetry Constraints: Discovering new materials is a challenging task in materials science crucial\nto the progress of human society. Conventional approaches based on experiments\nand simulations are labor-intensive or costly with success heavily depending on\nexperts' heuristic knowledge. Here, we propose a deep learning based Physics\nGuided Crystal Generative Model (PGCGM) for efficient crystal material design\nwith high structural diversity and symmetry. Our model increases the generation\nvalidity by more than 700\\% compared to FTCP, one of the latest structure\ngenerators and by more than 45\\% compared to our previous CubicGAN model.\nDensity Functional Theory (DFT) calculations are used to validate the generated\nstructures with 1,869 materials out of 2,000 are successfully optimized and\ndeposited into the Carolina Materials Database \\url{www.carolinamatdb.org}, of\nwhich 39.6\\% have negative formation energy and 5.3\\% have energy-above-hull\nless than 0.25 eV/atom, indicating their thermodynamic stability and potential\nsynthesizability."
    },
    {
        "anchor": "Cooperative emission of light by an ensemble of dipoles near a metal\n  nanostucture: The plasmonic Dicke effect: We identify a new mechanism for cooperative emission of light by an ensemble\nof N dipoles near a metal nanostructure supporting a surface plasmon.The\ncross-talk between emitters due to virtual plasmon exchange leads to a\nformation of three plasmonic super-radiant modes whose radiative decay rates\nscales with N, while the total radiated energy is thrice that of a single\nemitter. Our numerical simulations indicate that the plasmonic Dicke effect\nsurvives non-radiative losses in the metal.",
        "positive": "Limitations for the determination of piezoelectric constants with\n  piezoresponse force microscopy: At first sight piezoresponse force microscopy (PFM) seems an ideal technique\nfor the determination of piezoelectric coefficients (PCs), thus making use of\nits ultra-high vertical resolution (<0.1 pm/V). Christman et al. \\cite{Chr98}\nfirst used PFM for this purpose. Their measurements, however, yielded only\nreasonable results of unsatisfactory accuracy, amongst others caused by an\nincorrect calibration of the setup. In this contribution a reliable calibration\nprocedure is given followed by a careful analysis of the encounted difficulties\ndetermining PCs with PFM. We point out different approaches for their solution\nand expose why, without an extensive effort, those difficulties can not be\ncircumvented."
    },
    {
        "anchor": "Revealing the Origin of Luminescence Center in 0D Cs4PbBr6 Perovskite: Zero dimensional perovskite Cs4PbBr6 has attracted considerable attention\nrecently not only because of its highly efficient green photoluminescence (PL),\nbut also its two highly debated opposing mechanisms of the luminescence:\nembedded CsPbBr3 nanocrystals versus intrinsic Br vacancy states. After a brief\ndiscussion on the root cause of the controversy, we provide sensitive but\nnon-invasive methods that can not only directly correlate luminescence with the\nunderlying structure, but also distinguish point defects from embedded\nnanostructures. We first synthesized both emissive and non-emissive Cs4PbBr6\ncrystals, obtained the complete Raman spectrum of Cs4PbBr6 and assigned all\nRaman bands based on density functional theory simulations. We then used\ncorrelated Raman-PL as a passive structure-property method to identify the\ndifference between emissive and non-emissive Cs4PbBr6 crystals and revealed the\nexistence of CsPbBr3 nanocrystals in emissive Cs4PbBr6. We finally employed a\ndiamond anvil cell to probe the response of luminescence centers to hydrostatic\npressure. The observations of fast red-shifting, diminishing and eventual\ndisappearance of both green emission and Raman below Cs4PbBr6 phase transition\npressure of ~3 GPa is compatible with CsPbBr3 nanocrystal inclusions as green\nPL emitters and cannot be explained by Br vacancies. The resolution of this\nlong-lasting controversy paves the way for further device applications of low\ndimensional perovskites, and our comprehensive optical technique integrating\nstructure-property with dynamic pressure response is generic and can be applied\nto other emerging optical materials to understand the nature of their\nluminescent centers.",
        "positive": "Real-Space Visualization of Frequency-Dependent Anisotropy of Atomic\n  Vibrations: The underlying dielectric properties of materials, intertwined with\nintriguing phenomena such as topological polariton modes and anisotropic\nthermal conductivities, stem from the anisotropy in atomic vibrations.\nConventionally, X-ray diffraction techniques have been employed to estimate\nthermal ellipsoids of distinct elements, albeit lacking the desired spatial and\nenergy resolutions. Here we introduce a novel approach utilizing the dark-field\nmonochromated electron energy-loss spectroscopy for momentum-selective\nvibrational spectroscopy, enabling the cartographic delineation of variations\nof phonon polarization vectors. By applying this technique to centrosymmetric\ncubic-phase strontium titanate, we successfully discern two types of oxygen\natoms exhibiting contrasting vibrational anisotropies below and above 60 meV\ndue to their frequency-linked thermal ellipsoids. This method establishes a new\npathway to visualize phonon eigenvectors at specific crystalline sites for\ndiverse elements, thus delving into uncharted realms of dielectric, optical,\nand thermal property investigations with unprecedented spatial resolutions."
    },
    {
        "anchor": "Adaptively Biased Molecular Dynamics for Free Energy Calculations: We present an Adaptively Biased Molecular Dynamics (ABMD) method for the\ncomputation of the free energy surface of a reaction coordinate using\nnon-equilibrium dynamics. The ABMD method belongs to the general category of\numbrella sampling methods with an evolving biasing potential, and is inspired\nby the metadynamics method. The ABMD method has several useful features,\nincluding a small number of control parameters, and an $O(t)$ numerical cost\nwith molecular dynamics time $t$. The ABMD method naturally allows for\nextensions based on multiple walkers and replica exchange, where different\nreplicas can have different temperatures and/or collective variables. This is\nbeneficial not only in terms of the speed and accuracy of a calculation, but\nalso in terms of the amount of useful information that may be obtained from a\ngiven simulation. The workings of the ABMD method are illustrated via a study\nof the folding of the Ace-GGPGGG-Nme peptide in a gaseous and solvated\nenvironment.",
        "positive": "Elastic Mid-Infrared Light Scattering: a Basis for Microscopy of\n  Large-Scale Electrically Active Defects in Semiconducting Materials: A method of the mid-IR-laser microscopy has been proposed for the\ninvestigation of the large-scale electrically and recombination active defects\nin semiconductors and non-destructive inspection of semiconductor materials and\nstructures in the industries of microelectronics and photovoltaics. The basis\nfor this development was laid with a wide cycle of the investigations on the\nlow-angle mid-IR-light scattering in semiconductors. The essence of the\ntechnical idea was to apply the dark-field method for spatial filtering of the\nscattered light in the scanning mid-IR-laser microscope. This approach enabled\nthe visualization of large-scale electrically active defects which are the\nregions enriched with ionized electrically active centers. The photoexcitation\nof excess carriers within a small volume located in the probe mid-IR-laser beam\nenabled the visualization of the large-scale recombination-active defects like\nthose revealed in the optical or electron beam induced current methods. Both\nthese methods of the scanning mid-IR-laser microscopy are now introduced in\ndetail in the present paper as well as a summary of techniques used in the\nstandard method of the lowangle mid-IR-light scattering itself. Besides the\ntechniques for direct observations, methods for analyses of the defect\ncomposition associated with the mid-IR-laser microscopy are also discussed in\nthe paper."
    },
    {
        "anchor": "Density-functional description of superconducting and magnetic proximity\n  effects across a tunneling barrier: A density-functional formalism for superconductivity {\\em and} magnetism is\npresented. The resulting relations unify previously derived Kohn-Sham equations\nfor superconductors and for non-collinear magnetism. The formalism, which\ndiscriminates Cooper pair singlets from triplets, is applied to two quantum\nliquids coupled by tunneling through a barrier. An exact expression is derived,\nrelating the eigenstates and eigenvalues of the Kohn-Sham equations,\nunperturbed by tunneling, on one side of the barrier to the proximity-induced\nordering potential on the other.",
        "positive": "Preparation and characterization of an anionic dye-polycation molecular\n  films by electrostatic Layer-by-Layer adsorption process: This communication reports the formation and characterization of self\nassembled films of a low molecular weight anionic dye amaranth and polycation\nPoly (allylamine hydrochloride) (PAH) by electrostatic alternating\nLayer-by-Layer (LBL) adsorption. It was observed that there was almost no\nmaterial loss occurred during adsorption process. The UV-Vis absorption and\nfluorescence spectra of amaranth solution reveal that with the increase in\namaranth concentration in solution, the aggregated species starts to dominate\nover the monomeric species. New aggregated band at 600 nm was observed in\namaranth-PAH mixture solution absorption spectrum. A new broad low intense band\nat the longer wavelength region, in the amaranth-PAH mixture solution\nfluorescence spectrum was observed due to the closer association of amaranth\nmolecule while tagged into the polymer backbone of PAH and consequent formation\nof aggregates. The broad band system in the 650-750 nm region in the\nfluorescence spectra of different layered LBL films changes in intensity\ndistribution among various bands within itself, with changing layer number and\nat 10 bilayer LBL films the longer wavelength band at 710 nm becomes prominent.\nExistence of dimeric or higher order n-meric species in the LBL films was\nconfirmed by excitation spectroscopic studies. Almost 45 minute was required to\ncomplete the interaction between amaranth and PAH molecules in the 1-bilayer\nLBL film."
    },
    {
        "anchor": "Energy structure, density of states and transmission properties of the\n  periodic 1D Tight-Binding lattice with a generic unit cell of $u$ sites: We report on the electronic structure, density of states and transmission\nproperties of the periodic one-dimensional Tight-Binding (TB) lattice with a\nsingle orbital per site and nearest-neighbor interactions, with a generic unit\ncell of $u$ sites. The determination of the eigenvalues is equivalent to the\ndiagonalization of a real tridiagonal symmetric $u$-Toeplitz matrix with\n(cyclic boundaries) or without (fixed boundaries) perturbed upper right and\nlower left corners. We solve the TB equations via the Transfer Matrix Method,\nproducing, analytical solutions and recursive relations for its eigenvalues,\nclosely related to the Chebyshev polynomials. We examine the density of states\nand provide relevant analytical relations. We attach semi-infinite leads,\ndetermine and discuss the transmission coefficient at zero bias and investigate\nthe peaks number and position, and the effect of the coupling strength and\nasymmetry as well as of the lead properties on the transmission profiles. We\nintroduce a generic optimal coupling condition and demonstrate its physical\nmeaning.",
        "positive": "Interlayer Sliding-Induced Intralayer Ferroelectric Switching in Bilayer\n  Group-IV Monochalcogenides: Two-dimensional materials with ferroelectric properties break the size effect\nof conventional ferroelectric materials and unlock unprecedented potentials of\nferroelectric-related application at small length scales. In this work, using\ndensity functional theory (DFT) calculations, we discover a\ntribo-ferroelectricity behavior in a group of bilayer group-IV\nmonochalcogenides (MX, with M = Ge, Sn and X = S, Se). Upon interlayer sliding\nover an in-plane unit cell length, the top layer exhibits a reversible\nintralayer ferroelectric switching, leading to a reversible transition between\nthe ferroelectric (electric polarization of 40$\\mu$C/cm$^2$) and\nantiferroelectric states in the bilayer MXs. Our results show that the\ninterlayer van der Waals interaction, which is usually considered to be weak,\ncan actually generate an in-plane lattice distortion and thus cause the\nbreaking/forming of intralayer covalent bonds in the top layer, leading to the\nobserved tribo-ferroelectricity phenomenon. This unique property has several\nadvantages for energy harvesting over existing piezoelectric and triboelectric\nnanogenerators. The interlayer sliding-induced polarization change is as high\nas 40$\\mu$C/cm$^2$, which can generate an open-circuit voltage two orders of\nmagnitude higher than that of MoS$_2$-based nanogenerators. The polarization\nchange occurs over a time period for interlayer sliding over a unit-cell\nlength, leading to an ultrahigh polarization changing rate and thus an\nultrahigh short-circuit current. The theoretical prediction of power output for\nthe tribo-ferroelectric bilayer MXs at a moderate sliding speed 1 m/s is four\norders of magnitude higher than the MoS$_2$ nanogenerator, indicating great\npotentials in energy harvesting applications."
    },
    {
        "anchor": "Rashba splitting in polar-nonpolar sandwich heterostructure : A DFT\n  Study: In this study, we employ density functional theory (DFT) based\nfirst-principles calculations to investigate the spin-orbit effects in the\nelectronic structure of a polar-nonpolar sandwich heterostructure namely\nLAO$_{2.5}$/STO$_{5.5}$/LAO$_{2.5}$. Our focus on the Ti-3d bands reveals an\ninverted ordering of the STO-$\\rm t_{2g}$ orbital near the n-type interface,\nconsistent with earlier experimental work. In contrast, toward the p-type\ninterface, the orbital ordering aligns with the natural ordering of STO\norbitals, influenced by crystal field splitting. Interestingly, we have found a\nstrong inter-orbital coupling between $t_{2g}$ and $e_g$ orbital, which has not\nbeen reported earlier in $\\rm SrTiO_3$ based 2D system. Additionally, our\nobservations highlight that the cubic Rashba splitting in this system surpasses\nthe linear Rashba splitting, contrary to experimental findings. This\ncomprehensive analysis contributes to a refined understanding of the role of\norbital mixing in Rashba splitting in the sandwich oxide heterostructures.",
        "positive": "Towards a first-principles theory of surface thermodynamics and kinetics: Understanding of the complex behavior of particles at surfaces requires\ndetailed knowledge of both macroscopic and microscopic processes that take\nplace; also certain processes depend critically on temperature and gas\npressure. To link these processes we combine state-of-the-art microscopic, and\nmacroscopic phenomenological, theories. We apply our theory to the O/Ru(0001)\nsystem and calculate thermal desorption spectra, heat of adsorption, and the\nsurface phase diagram. The agreement with experiment provides validity for our\napproach which thus identifies the way for a predictive simulation of surface\nthermodynamics and kinetics."
    },
    {
        "anchor": "Resonant low-energy electron scattering on short-range impurities in\n  graphene: Resonant scattering of electrons with low energies (as compared to the\nbandwidth) on a single neutral short-range impurity in graphene is analyzed\ntheoretically, taking into account the valley degeneracy. Resonances\ndramatically increase the scattering cross-section and introduce a strong\nenergy dependence. Analysis of the tight-binding model shows that resonant\nscattering is typical for generic impurities as long as they are sufficiently\nstrong (the potential is of the order of the electron bandwidth or higher).",
        "positive": "Mixed Weyl semimetals and dissipationless magnetization control in\n  insulators by spin-orbit torques: Reliable and energy efficient magnetization switching by electrically-induced\nspin-orbit torques is of crucial technological relevance for spintronic devices\nimplementing memory and logic functionality. Here we predict that the strength\nof spin-orbit torques and the related Dzyaloshinskii-Moriya interaction in\ntopologically non-trivial magnetic insulators can exceed by far that of\nconventional metallic magnets. In analogy to the quantum anomalous Hall effect,\nwe explain this extraordinary response in absence of longitudinal currents as a\nhallmark of magnetic monopoles in the electronic structure of systems that are\ninterpreted most naturally within the framework of mixed Weyl semimetals. We\nthereby launch the effect of spin-orbit torque into the field of topology and\nreveal its crucial role in mediating the topological phase transitions arising\ndue to the complex interplay between magnetization direction and momentum-space\ntopology. The concepts presented here may be exploited to understand and\nutilize magneto-electric coupling phenomena in insulating ferromagnets and\nantiferromagnets."
    },
    {
        "anchor": "Properties and challenges of hot-phonon physics in metals: MgB$_2$ and\n  other compounds: The ultrafast dynamics of electrons and collective modes in systems out of\nequilibrium is crucially governed by the energy transfer from electronic\ndegrees of freedom, where the energy of the pump source is usually absorbed, to\nlattice degrees of freedom. In conventional metals such process leads to an\noverall heating of the lattice, usually described by an effective lattice\ntemperature $T_{\\rm ph}$, until final equilibrium with all the degrees of\nfreedom is reached. In specific materials, however, few lattice modes provide a\npreferential channel for the energy transfer, leading to a non-thermal\ndistribution of vibrations and to the onset of {\\em hot phonons}, i.e., lattice\nmodes with a much higher population than the other modes. Hot phonons are\nusually encountered in semiconductors or semimetal compounds, like graphene,\nwhere the preferential channel towards hot modes is dictated by the reduced\nelectronic phase space. Following a different path, the possibility of\nobtaining hot-phonon physics also in metals has been however also recently\nprompted in literature, as a result of a strong anisotropy of the\nelectron-phonon (el-ph) coupling. In the present paper, taking MgB$_2$ as a\nrepresentative example, we review the physical conditions that allow a\nhot-phonon scenario in metals with anisotropic el-ph coupling, and we discuss\nthe observable fingerprints of hot phonons. Novel perspectives towards the\nprediction and experimental observation of hot phonons in other metallic\ncompounds are also discussed.",
        "positive": "Effects of configurational disorder on adatom mobilities on TiAlN(001)\n  surfaces: We use metastable NaCl-structure Ti0.5Al0.5N alloys to probe effects of\nconfigurational disorder on adatom surface diffusion dynamics which control\nphase stability and nanostructural evolution during film growth.\nFirst-principles calculations were employed to obtain potential energy maps of\nTi and Al adsorption on an ordered TiN(001) reference surface and a disordered\nTi0.5Al0.5N(001) solid-solution surface. The energetics of adatom migration on\nthese surfaces are determined and compared in order to isolate effects of\nconfigurational disorder. The results show that alloy surface disorder\ndramatically reduces Ti adatom mobilities. Al adatoms, in sharp contrast,\nexperience only small disorder-induced differences in migration dynamics."
    },
    {
        "anchor": "Piezoelectric nonlinearity and frequency dispersion of the direct\n  piezoelectric response of BiFeO3 ceramics: We report on the frequency and stress dependence of the direct piezoelectric\nd33 coefficient in BiFeO3 ceramics. The measurements reveal considerable\npiezoelectric nonlinearity, i.e., dependence of d33 on the amplitude of the\ndynamic stress. The nonlinear response suggests a large irreversible\ncontribution of non-180{\\deg} domain walls to the piezoelectric response of the\nferrite, which, at present measurement conditions, reached a maximum of 38% of\nthe total measured d33. In agreement with this interpretation, both types of\nnon-180{\\deg} domain walls, characteristic for the rhombohedral BiFeO3, i.e.,\n71{\\deg} and 109{\\deg}, were identified in the poled ceramics using\ntransmission electron microscopy (TEM). In support to the link between\nnonlinearity and non-180{\\deg} domain wall contribution, we found a correlation\nbetween nonlinearity and processes leading to deppining of domain walls from\ndefects, such as quenching from above the Curie temperature and\nhigh-temperature sintering. In addition, the nonlinear piezoelectric response\nof BiFeO3 showed a frequency dependence that is qualitatively different from\nthat measured in other nonlinear ferroelectric ceramics, such as \"soft\"\n(donor-doped) Pb(Zr,Ti)O3 (PZT); possible origins of this dispersion are\ndiscussed. Finally, we show that, once released from pinning centers, the\ndomain walls can contribute extensively to the electromechanical response of\nBiFeO3; in fact, the extrinsic domain-wall contribution is relatively as large\nas in Pb-based ferroelectric ceramics with morphotropic phase boundary (MPB)\ncomposition, such as PZT. This finding might be important in the search of new\nlead-free MPB compositions based on BiFeO3 as it suggests that such\ncompositions might also exhibit large extrinsic domain-wall contribution to the\npiezoelectric response.",
        "positive": "Breaking time reversal symmetry in topological insulators: A wide class of materials that were discovered to carry a topologically\nprotected phase order has led to a highly active area of research called\ntopological insulators. This phenomenon has radically changed our thinking\nbecause of their robust quantum coherent behavior showing two-dimensional\nDirac-type metallic surface states and simultaneously insulating bulk states.\nThe Dirac SSs are induced by the strong spin-orbit coupling as well as\nprotected by the time reversal symmetry. Breaking TRS in a TI with\nferromagnetic perturbation can lead to many exotic quantum phenomena, such as\nthe quantum anomalous Hall effect, topological magnetoelectric effect, as well\nas image magnetic monopole. This article presents an overview of the current\nstatus of TRS breaking in TIs and outlines the prospects for future studies"
    },
    {
        "anchor": "Structural phase transition in IrTe$_2$: A combined study of optical\n  spectroscopy and band structure calculations: Ir$_{1-x}$Pt$_x$Te$_2$ is an interesting system showing competing phenomenon\nbetween structural instability and superconductivity. Due to the large atomic\nnumbers of Ir and Te, the spin-orbital coupling is expected to be strong in the\nsystem which may lead to nonconventional superconductivity. We grew single\ncrystal samples of this system and investigated their electronic properties. In\nparticular, we performed optical spectroscopic measurements, in combination\nwith density function calculations, on the undoped compound IrTe$_2$ in an\neffort to elucidate the origin of the structural phase transition at 280 K. The\nmeasurement revealed a dramatic reconstruction of band structure and a\nsignificant reduction of conducting carriers below the phase transition. We\nelaborate that the transition is not driven by the density wave type\ninstability but caused by the crystal field effect which further\nsplits/separates the energy levels of Te (p$_x$, p$_y$) and Te p$_z$ bands.",
        "positive": "Structural and emission properties of Tb3+-doped nitrogen-rich silicon\n  oxynitride films: Terbium doped silicon oxynitride host matrix is suitable for various\napplications such as light emitters compatible with CMOS technology or\nfrequency converter systems for photovoltaic cells. In this study, amorphous\nTb3+ ion doped nitrogen-rich silicon oxynitride (NRSON) thin films were\nfabricated using a reactive magnetron co-sputtering method, with various N2\nflows and annealing conditions, in order to study their structural and emission\nproperties. Rutherford backscattering (RBS) measurements and refractive index\nvalues confirmed the silicon oxynitride nature of the films. An electron\nmicroscopy analysis conducted for different annealing temperatures (T A) was\nalso performed up to 1200 {\\textdegree}C. Transmission electron microscopy\n(TEM) images revealed two different sublayers. The top layer showed porosities\ncoming from a degassing of oxygen during deposition and annealing, while in the\nregion close to the substrate, a multilayer-like structure of SiO2 and Si3N4\nphases appeared, involving a spinodal decomposition. Upon a 1200 {\\textdegree}C\nannealing treatment, a significant density of Tb clusters was detected,\nindicating a higher thermal threshold of rare earth (RE) clusterization in\ncomparison to the silicon oxide matrix. With an opposite variation of the N2\nflow during the deposition, the nitrogen excess parameter (Nex) estimated by\nRBS measurements was introduced to investigate the Fourier transform infrared\n(FTIR) spectrum behavior and emission properties. Different vibration modes of\nthe Si--N and Si--O bonds have been carefully identified from the FTIR spectra\ncharacterizing such host matrices, especially the 'out-of-phase' stretching\nvibration mode of the Si--O bond. The highest Tb3+ photoluminescence (PL)\nintensity was obtained by optimizing the N incorporation and the annealing\nconditions. In addition, according to these conditions, the integrated PL\nintensity variation confirmed that the silicon nitride-based host matrix had a\nhigher thermal threshold of rare earth clusterization than its silicon oxide\ncounterpart. Analysis of time-resolved PL intensity versus T A showed the\nimpact of Tb clustering on decay times, in agreement with the TEM observations.\nFinally, PL and PL excitation (PLE) experiments and comparison of the related\nspectra between undoped and Tb-doped samples were carried out to investigate\nthe impact of the band tails on the excitation mechanism of Tb3+ ions."
    },
    {
        "anchor": "Numerical correction of anti-symmetric aberrations in single HRTEM\n  images of weakly scattering 2D-objects: Here, we present a numerical post-processing method for removing the effect\nof anti-symmetric residual aberrations in high-resolution transmission electron\nmicroscopy (HRTEM) images of weakly scattering 2D-objects. The method is based\non applying the same aberrations with the opposite phase to the Fourier\ntransform of the recorded image intensity and subsequently inverting the\nFourier transform. We present the theoretical justification of the method and\nits verification based on simulated images in the case of low-order\nanti-symmetric aberrations. Ultimately the method is applied to experimental\nhardware aberration-corrected HRTEM images of single-layer graphene and MoSe2\nresulting in images with strongly reduced residual low-order aberrations, and\nconsequently improved interpretability. Alternatively, this method can be used\nto estimate by trial and error the residual anti-symmetric aberrations in HRTEM\nimages of weakly scattering objects.",
        "positive": "Effective Willis constitutive equations for periodically stratified\n  anisotropic elastic media: A method to derive homogeneous effective constitutive equations for\nperiodically layered elastic media is proposed. The crucial and novel idea\nunderlying the procedure is that the coefficients of the dynamic effective\nmedium can be associated with the matrix logarithm of the propagator over a\nunit period. The effective homogeneous equations are shown to have the\nstructure of a Willis material, characterized by anisotropic inertia and\ncoupling between momentum and strain, in addition to effective elastic\nconstants. Expressions are presented for the Willis material parameters which\nare formally valid at any frequency and horizontal wavenumber as long as the\nmatrix logarithm is well defined. The general theory is illustrated using the\nexample of scalar SH motion. Low frequency, long wavelength expansions of the\neffective material parameters are also developed using a Magnus series and\nexplicit estimates for the rate of convergence are derived."
    },
    {
        "anchor": "Electrically pumped polarized exciton-polaritons in a halide perovskite\n  microcavity: Exciton polaritons, hybrid quasiparticles with part-light part-matter nature\nin semiconductor microcavities, are extensively investigated for striking\nphenomena such as polariton condensation and quantum emulation. These phenomena\nhave recently been discovered in emerging lead halide perovskites at elevated\ntemperatures up to room temperature. For advancing these discoveries into\npractical applications, one critical requirement is the realization of\nelectrically pumped exciton-polaritons. However, electrically pumped polariton\nlight-emitting devices with perovskites have not yet been achieved\nexperimentally. Here, we devise a new method to combine the device with the\nmicrocavity and report the first halide perovskite polariton light-emitting\ndevice. Specifically, the device is based on a CsPbBr3 capacitive structure,\nwhich can inject the electrons and holes from the same electrode, conducive to\nthe formation of excitons and simultaneously maintaining the high quality of\nthe microcavity. In addition, highly polarization-selective polariton emissions\nhave been demonstrated due to the optical birefringence in the CsPbBr3\nmicroplate. This work paves the way for realizing practical polaritonic devices\nsuch as high-speed light-emitting devices for information communications and\ninversionless electrically pumped lasers based on perovskites.",
        "positive": "Submonolayer epitaxy with impurities: The effect of impurities on epitaxial growth in the submonolayer regime is\nstudied using kinetic Monte Carlo simulations of a two-species solid-on-solid\ngrowth model. Both species are mobile, and attractive interactions among\nadatoms and between adatoms and impurities are incorporated. Impurities can be\ncodeposited with the growing material or predeposited prior to growth. The\nactivated exchange of impurities and adatoms is identified as the key kinetic\nprocess in the formation of a growth morphology in which the impurities\ndecorate the island edges. The dependence of the island density on flux and\ncoverage is studied in detail. The impurities strongly increase the island\ndensity without appreciably changing its power-law dependence on flux, apart\nfrom a saturation of the flux dependence at high fluxes and low coverages. A\nsimple analytic theory taking into account only the dependence of the adatom\ndiffusion constant on impurity coverage is shown to provide semi-quantitative\nagreement with many features observed in the simulations."
    },
    {
        "anchor": "Photo-switchable nanoripples in Ti3C2Tx MXene: MXenes are two-dimensional materials with a rich set of remarkable chemical\nand electromagnetic properties, the latter including saturable absorption and\nintense surface plasmon resonances. To fully harness the functionality of\nMXenes for applications in optics, electronics and sensing, it is important to\nunderstand the interaction of light with MXenes on atomic and femtosecond\ndimensions. Here, we use ultrafast electron diffraction and high-resolution\nelectron microscopy to investigate the laser-induced structural dynamics of\nTi3C2Tx nanosheets. We find an exceptionally fast lattice response with an\nelectron-phonon coupling time of 230 femtoseconds. Repetitive femtosecond laser\nexcitation transforms Ti3C2Tx through a structural transition into a\nmetamaterial with deeply sub-wavelength nanoripples that are aligned with the\nlaser polarization. By a further laser illumination, the material is reversibly\nphoto-switchable between a flat and rippled morphology. The resulting\nnanostructured MXene metamaterial with directional nanoripples is expected to\nexhibit an anisotropic optical and electronic response as well as an enhanced\nchemical activity that can be switched on and off by light.",
        "positive": "Effective chemical potential for non-equilibrium systems and its\n  application to molecular beam epitaxy of Bi2Se3: First-principles studies often rely on the assumption of equilibrium, which\ncan be a poor approximation, e.g., for growth. Here, an effective chemical\npotential method for non-equilibrium systems is developed. A salient feature of\nthe theory is that it maintains the equilibrium limits as the correct limit. In\napplication to molecular beam epitaxy, rate equations are solved for the\nconcentrations of small clusters, which serve as feedstock for growth. We find\nthat the effective chemical potential is determined by the most probable,\nrather than by the lowest-energy, cluster. In the case of Bi2Se3, the chemical\npotential is found to be highly supersaturated, leading to a high nucleus\nconcentration in agreement with experiment."
    },
    {
        "anchor": "Lattice dynamics and phase stability of rhombohedral antimony under high\n  pressure: The high pressure lattice dynamics of rhombohedral antimony have been studied\nby a combination of diffuse scattering and inelastic x-ray scattering. The\nevolution of the phonon behavior as function of pressure was analyzed by means\nof two theoretical approaches: density functional perturbation theory and\nsymmetry-based phenomenological phase transition analysis. This paper focuses\non the first structural phase transition, SbI-SbIV, and the role of vibrations\nin leading the transition. The phonon dispersion exhibits complex behaviour as\none approaches the structural transition, with the branches, corresponding to\nthe two transitions happening at high pressure in the Va elements (A7-to-BCC\nand A7-to-PC) both showing softening.",
        "positive": "An Array of Layers in Silicon Sulfides: Chain-like and Ground State\n  Structures: While much is known about isoelectronic materials related to carbon\nnanostructures, such as boron nitride layers and nanotubes, rather less is\nknown about equivalent silicon based materials. Following the recent discovery\nof phosphorene, we herein discuss isoelectronic silicon monosulfide monolayers.\nWe describe a set of anisotropic ground state structures that clearly have a\nhigh stability with respect to the near isotropic silicon monosulfide\nmonolayers. The source of the layer anisotropy is related to the presence of\nSi-S double chains linked by some Si-Si covalent bonds, which lye at the core\nof the increased stability, together with a remarkable spd hybridization on Si.\nThe involvement of d orbitals brings more variety to silicon-sulfide based\nnanostructures that are isoelectronic to phosphorene, which could be relevant\nfor future applications, adding extra degrees of freedom."
    },
    {
        "anchor": "Molecular Beam Epitaxy Growth of [CrGe/MnGe/FeGe] Superlattices: Toward\n  Artificial B20 Skyrmion Materials with Tunable Interactions: Skyrmions are localized magnetic spin textures whose stability has been shown\ntheoretically to depend on material parameters including bulk Dresselhaus spin\norbit coupling (SOC), interfacial Rashba SOC, and magnetic anisotropy. Here, we\nestablish the growth of a new class of artificial skyrmion materials, namely\nB20 superlattices, where these parameters could be systematically tuned.\nSpecifically, we report the successful growth of B20 superlattices comprised of\nsingle crystal thin films of FeGe, MnGe, and CrGe on Si(111) substrates. Thin\nfilms and superlattices are grown by molecular beam epitaxy and are\ncharacterized through a combination of reflection high energy electron\ndiffraction, x-ray diffraction, and cross-sectional scanning transmission\nelectron microscopy (STEM). X-ray energy dispersive spectroscopy (XEDS)\ndistinguishes layers by elemental mapping and indicates good interface quality\nwith relatively low levels of intermixing in the [CrGe/MnGe/FeGe] superlattice.\nThis demonstration of epitaxial, single-crystalline B20 superlattices is a\nsignificant advance toward tunable skyrmion systems for fundamental scientific\nstudies and applications in magnetic storage and logic.",
        "positive": "Photovoltaic response around a unique180{\\textdegree} ferroelectric\n  domain wall in single crystalline BiFeO3: Using an experimental setup designed to scan a submicron sized light spot and\ncollect the photogenerated current through larger electrodes, we map the\nphotovoltaic response in ferroelectric BiFeO3 single crystals. We study the\neffect produced by a unique 180{\\textdegree} ferroelectric domain wall (DW) and\nshow that the photocurrent maps are significantly affected by its presence and\nshape. The effect is large in its vicinity and in the Schottky barriers at the\ninterface with the Au electrodes, but no extra photocurrent is observed when\nthe illuminating spot touches the DW, indicating that this particular entity is\nnot the heart of specific photo-electric properties. Using 3D modelling, we\nargue that the measured effect is due to the spatial distribution of internal\nfields which are significantly affected by the charge of the DW due to its\ndistortion."
    },
    {
        "anchor": "Magnetocaloric properties of LaFe$_{13-x-y}$Co$_x$Si$_y$ and commercial\n  grade Gd: The magnetocaloric properties of three samples of LaFe$_{13-x-y}$Co$_x$Si$_y$\nhave been measured and compared to measurements of commercial grade Gd. The\nsamples have (x=0.86, y=1.08), (x=0.94, y=1.01) and (x=0.97, y=1.07) yielding\nCurie temperatures in the range 276-288 K. The magnetization, specific heat\ncapacity and adiabatic temperature change have been measured over a broad\ntemperature interval. Importantly, all measurements were corrected for\ndemagnetization, allowing the data to be directly compared. In an internal\nfield of 1 T the maximum specific entropy changes were 6.2, 5.1 and 5.0 J/kg K,\nthe specific heat capacities were 910, 840 and 835 J/kg K and the adiabatic\ntemperature changes were 2.3, 2.1 and 2.1 K for the three LaFeCoSi samples\nrespectively. For Gd in an internal field of 1 T the maximum specific entropy\nchange was 3.1 J/kg K, the specific heat capacity was 340 J/kg K and the\nadiabatic temperature change was 3.3 K. The adiabatic temperature change was\nalso calculated from the measured values of the specific heat capacity and\nspecific magnetization and compared to the directly measured values. In general\nan excellent agreement was seen.",
        "positive": "Interplay of the Jahn--Teller Effect and Spin-Orbit Coupling: The Case\n  of Trigonal Vibronic Modes: We study an interplay between the orbital degeneracy and spin-orbit coupling\ngiving rise to spin-orbital entangled states. As a specific example, we analyze\nthe interaction of electrons occupying triply degenerate single-ion $t_{2g}$\nlevels with trigonal vibronic modes (the $t\\otimes T$ problem). A more general\nproblem of the electron-lattice interaction involving both tetragonal and\ntrigonal vibrations is also considered. It is shown that the result of such\ninteraction crucially depends on the occupation of $t_{2g}$ levels leading to\neither the suppression or enhancement of the Jahn-Teller effect by the\nspin-orbit coupling."
    },
    {
        "anchor": "Excitonic effects on the third-order nonlinear optical properties of\n  solids: Theory and application: We present a many-body Bethe-Salpeter equation eigenstates based\nsum-over-states method to calculate the linear and nonlinear optical properties\nof solids. Excitonic and local field effects are included in the calculations.\nAs applications, we calculate the one-photon absorption, third harmonic\ngeneration, degenerate four-wave mixing spectra of solid C60 fullerene. The\noverall agreement between the theoretical and experimental results is very good\nfor all three calculated spectra. By comparisons with the independent particle\napproximation based sum-over-states method, we show that excitonic effects mix\nthe independent particle transition peaks to new excitonic ones. The position\nand intensity of spectral peaks are modified significantly. By tracing the\nsum-over-states progress, we determine the type of nonlinear polarization\nresonances for the characteristic peaks of third harmonic generation process,\nwhich may clear up a discrepancy in two experimental results.",
        "positive": "Size dependent thermoelectric properties of silicon nanowires: By using first-principles tight-binding electronic structure calculation and\nBoltzmann transport equation, we investigate the size dependence of\nthermoelectric properties of silicon nanowires (SiNWs). With cross section area\nincreasing, the electrical conductivity increases slowly, while the Seebeck\ncoefficient reduces remarkably. This leads to a quick reduction of cooling\npower factor with diameter. Moreover, the figure of merit also decreases with\ntransverse size. Our results demonstrate that in thermoelectric application, NW\nwith small diameter is preferred. We also predict that isotopic doping can\nincrease the value of ZT significantly. With 50% 29Si doping (28Si0.529Si0.5\nNW), the ZT can be increased by 31%."
    },
    {
        "anchor": "Coexistence of multiple silicene phases in silicon grown on Ag(111): Silicene, the silicon equivalent of graphene, is attracting increasing\nscientific and technological attention in view of the exploitation of its\nexotic electronic properties. This novel material has been theoretically\npredicted to exist as a free-standing layer in a low-buckled, stable form, and\ncan be synthesized by the deposition of Si on appropriate crystalline\nsubstrates. By employing low-energy electron diffraction and microscopy, we\nhave studied the growth of Si on Ag(111) and observed a rich variety of\nrotationally non-equivalent silicene structures. Our results highlight a very\ncomplex formation diagram, reflecting the coexistence of different and nearly\ndegenerate silicene phases, whose relative abundance can be controlled by\nvarying the Si coverage and growth temperature. At variance with other studies,\nwe find that the formation of single-phase silicene monolayers cannot be\nachieved on Ag(111).",
        "positive": "Elasticity of Fractal Material by Continuum Model with Non-Integer\n  Dimensional Space: Using a generalization of vector calculus for space with non-integer\ndimension, we consider elastic properties of fractal materials. Fractal\nmaterials are described by continuum models with non-integer dimensional space.\nA generalization of elasticity equations for non-integer dimensional space, and\nits solutions for equilibrium case of fractal materials are suggested.\nElasticity problems for fractal hollow ball and cylindrical fractal elastic\npipe with inside and outside pressures, for rotating cylindrical fractal pipe,\nfor gradient elasticity and thermoelasticity of fractal materials are solved."
    },
    {
        "anchor": "Magnetic and ferroelectric properties of Sr$_{1-x}$Ba$_{x}$MnO$_3$ from\n  first principles: Density functional theory (DFT) calculations are used to study the magnetic\nand ferroelectric properties of Sr$_{1-x}$Ba$_{x}$MnO$_3$, with focus on\n$x=0.5$, under isotropic volume expansion/compression and biaxial strain. Our\nresults indicate that, unexpectedly, Ba substitution alters the electronic\nstructure in a way that, at fixed lattice parameter, notably enhances the\ninteratomic magnetic exchange interactions. However, increasing Ba-content also\ncauses a volume expansion which tends to weaken these interactions, leading to\na net effect of weakly suppressed magnetism, as observed in experiments. The\nferroelectric properties, on the other hand, are found to be less affected by\nchanges in the electronic structure and can largely be understood in terms of\nthe volume expansion caused by Ba-substitution. The calculated electric\npolarization as a function of biaxial strain in Sr$_{1-x}$Ba$_{x}$MnO$_3$ for\n$x=0$ and $x=0.5$, shows that the difference between the two is mainly due to\ndifferences in the magnetic order at certain strain values, accompanied by\nenormous magnetoelectric coupling.",
        "positive": "Chemical Self Assembly of Graphene Sheets: Chemically derived graphene sheets were found to self-assemble onto patterned\ngold structures via electrostatic interactions between noncovalent functional\ngroups on GS and gold. This afforded regular arrays of single graphene sheets\non large substrates, characterized by scanning electron and Auger microscopy\nimaging and Raman spectroscopy. Self assembly was used for the first time to\nproduce on-substrate and fully-suspended graphene electrical devices. Molecular\ncoatings on the GS were removed by high current electrical annealing, which\nrecovered the high electrical conductance and Dirac point of the GS. Molecular\nsensors for highly sensitive gas detections are demonstrated with\nself-assembled GS devices."
    },
    {
        "anchor": "Benchmarking acid and base dopants with respect to enabling the ice V to\n  XIII and ice VI to XV hydrogen-ordering phase transitions: Doping the hydrogen-disordered phases of ice V, VI and XII with hydrochloric\nacid (HCl) has led to the discovery of their hydrogen-ordered counterparts ices\nXIII, XV and XIV. Yet, the mechanistic details of the hydrogen-ordering phase\ntransitions are still not fully understood. This includes in particular the\nrole of the acid dopant and the defect dynamics that it creates within the\nices. Here we investigate the effects of several acid and base dopants on the\nhydrogen ordering of ices V and VI with calorimetry and X-ray diffraction. HCl\nis found to be most effective for both phases which is attributed to a\nfavourable combination of high solubility and strong acid properties which\ncreate mobile H3O+ defects that enable the hydrogen-ordering processes.\nHydrofluoric acid (HF) is the second most effective dopant highlighting that\nthe acid strengths of HCl and HF are much more similar in ice than they are in\nliquid water. Surprisingly, hydrobromic acid doping facilitates hydrogen\nordering in ice VI whereas only a very small effect is observed for ice V.\nConversely, lithium hydroxide (LiOH) doping achieves a performance comparable\nto HF-doping in ice V but it is ineffective in the case of ice VI. Sodium\nhydroxide, potassium hydroxide (as previously shown) and perchloric acid doping\nare ineffective for both phases. These findings highlight the need for future\ncomputational studies but also raise the question why LiOH-doping achieves\nhydrogen-ordering of ice V whereas potassium hydroxide doping is most effective\nfor the 'ordinary' ice Ih.",
        "positive": "Bulk topology of line-nodal structures protected by space group\n  symmetries in class AI: We give an exhaustive characterization of the topology of band structures in\nclass AI, using nonsymmorphic space group 33 ($Pna2_1$) as a representative\nexample where a great variety of symmetry protected line-nodal structures can\nbe formed. We start with the topological classification of all line-nodal\nstructures given through the combinatorics of valence irreducible\nrepresentations (IRREPs) at a few high-symmetry points (HSPs) at a fixed\nfilling. We decompose the total topology of nodal valence band bundles through\nthe local topology of elementary (i.e. inseparable) nodal structures and the\nglobal topology that constrains distinct elementary nodal elements over the\nBrillouin zone (BZ). Generalizing from the cases of simple point nodes and\nsimple nodal lines (NLs), we argue that the local topology of every elementary\nnodal structure is characterized by a set of poloidal-toroidal charges, one\nmonopole, and one thread charge (when threading the BZ torus), while the global\ntopology only allows pairs of nontrivial monopole and thread charges. We show\nthat all these charges are given in terms of symmetry protected topological\ninvariants, defined through quantized Wilson loop phases over symmetry\nconstrained momentum loops, which we derive entirely algebraically from the\nvalence IRREPs at the HSPs. In particular, we find highly connected line-nodal\nstructures, line-nodal monopole pairs, and line-nodal thread pairs, that are\nall protected by the unitary crystalline symmetries only. Furthermore, we show\nsymmetry preserving topological Lifshitz transitions through which independent\nNLs can be connected, disconnected, or linked. Our work constitutes a heuristic\napproach to the systematic topological classification and characterization of\nall momentum space line-nodal structures protected by space group symmetries in\nclass AI."
    },
    {
        "anchor": "High temperature behavior of Sr-doped layered cobaltites\n  Y(Ba1-xSrx)Co2O5.5: phase stability and structural properties: In this article we present a neutron diffraction in-situ study of the thermal\nevolution and high-temperature structure of layered cobaltites Y(Ba, Sr)Co2\nO5+{\\delta}. Neutron thermodiffractograms and magnetic susceptibility\nmeasurements are reported in the temperature range 20 K <= T <= 570 K, as well\nas high resolution neutron diffraction experiments at selected temperatures.\nStarting from the as-synthesized samples with {\\delta} ~ 0.5, we show that the\nroom temperature phases remain stable up to 550 K, where they start loosing\noxygen and transform to a vacancy-disordered \"112\" structure with tetragonal\nsymmetry. Our results also show how the so-called \"122\" structure can be\nstabilized at high temperature (around 450 K) in a sample in which the addition\nof Sr at the Ba site had suppressed its formation. In addition, we present the\nstructural and magnetic properties of the resulting samples with a new oxygen\ncontent {\\delta} ~ 0.25 in the temperature range 20 K <= T <= 300 K.",
        "positive": "Antiferrodistortive phase transition in EuTiO3: X-ray diffraction, dynamical mechanical analysis and infrared reflectivity\nstudies revealed an antiferrodistortive phase transition in EuTiO3 ceramics.\nNear 300K the perovskite structure changes from cubic Pm-3m to tetragonal\nI4/mcm due to antiphase tilting of oxygen octahedra along the c axis (a0a0c- in\nGlazer notation). The phase transition is analogous to SrTiO3. However, some\nceramics as well as single crystals of EuTiO3 show different infrared\nreflectivity spectra bringing evidence of a different crystal structure. In\nsuch samples electron diffraction revealed an incommensurate tetragonal\nstructure with modulation wavevector q ~ 0.38 a*. Extra phonons in samples with\nmodulated structure are activated in the IR spectra due to folding of the\nBrillouin zone. We propose that defects like Eu3+ and oxygen vacancies strongly\ninfluence the temperature of the phase transition to antiferrodistortive phase\nas well as the tendency to incommensurate modulation in EuTiO3."
    },
    {
        "anchor": "Prediction of femtosecond oscillations in the transient current of a\n  quantum dot in the Kondo regime: We invoke the time-dependent non-crossing approximation in order to study the\neffects of the density of states of gold contacts on the instantaneous\nconductance of a single electron transistor which is abruply moved into the\nKondo regime by means of a gate voltage. For an asymmetrically coupled system,\nwe observe that the instantaneous conductance in the Kondo timescale exhibits\nbeating with distinct frequencies, which are proportional to the separation\nbetween the Fermi level and the sharp features in the density of states of\ngold. Increasing the ambient temperature or bias quenches the amplitude of the\noscillations. We attribute the oscillations to interference between the\nemerging Kondo resonance and van-Hove singularities in the density of state. In\naddition, we propose an experimental realization of this model.",
        "positive": "Electron and hole doping of monolayer WSe2 induced by twisted\n  ferroelectric hexagonal boron nitride: For the past few years, 2D ferroelectric materials have attracted strong\ninterest for their potential in future nanoelectronics devices. The recent\ndiscovery of 2D ferroelectricity in twisted layers of insulating hexagonal\nboron nitride, one of the most used 2D materials, has opened the route to its\nintegration into complex van der Waals heterostructures combining hybrid\nproperties. Here we show that opposite polarizations in ferroelectric domains\nof a folded hBN layer can imprint local n and p doping in a semiconducting\ntransition metal dichalcogenide WSe2 monolayer. We demonstrate that WSe2 can be\nused as an optical probe of ferroelectricity in hBN and show that the doping\ndensity and type can be controlled with the position of the semiconductor with\nrespect to the ferroelectric interface. Our results establish the ferroelectric\nhBN/WSe2 van der Waals stacking as a promising optoelectronic structure."
    },
    {
        "anchor": "Investigations of RhB18 Langmuir monolayer by Fluorescence Imaging\n  Microscopy: This communication reports the surface pressure vs. area per molecule\nisotherm and Fluorescence Imaging Microscopic studies of the formation of\ndomain structure in the mixed Langmuir monolayer of RhB and Stearic acid (SA)\nat the air water interface. Strong repulsive interaction between the unlike\ncomponents leads to the phase separation and formation of microcrystalline\ndomains at the air water interface of the Langmuir monolayer. These domain can\nbe directly visualized using fluorescence imaging microscope.",
        "positive": "Inertial domain wall characterization in layered multisublattice\n  antiferromagnets: The motion of a N\\'eel-like ${180}^{\\circ}$ domain wall induced by a\ntime-dependent staggered spin-orbit field in the layered collinear\nantiferromagnet Mn$_2$Au is explored. Through an effective version of the two\nsublattice nonlinear $\\sigma$-model which does not take into account the\nantiferromagnetic exchange interaction directed along the tetragonal c-axis, it\nis possible to replicate accurately the relativistic and inertial traces\nintrinsic to the magnetic texture dynamics obtained through atomistic spin\ndynamics simulations for quasistatic processes. In the case in which the\nsteady-state magnetic soliton motion is extinguished due to the abrupt shutdown\nof the external stimulus, its stored relativistic exchange energy is\ntransformed into a complex translational mobility, being the rigid domain wall\nprofile approximation no longer suitable. Although it is not feasible to carry\nout a detailed follow-up of its temporal evolution in this case, it is possible\nto predict the inertial-based distance travelled by the domain wall in relation\nto its steady-state relativistic mass. This exhaustive dynamical\ncharacterization for different time-dependent regimes of the driving force is\nof potential interest in antiferromagnetic domain wall-based device\napplications."
    },
    {
        "anchor": "Scanning tunneling microscopy study of hidden phases in atomically thin\n  1T-TaS$_2$: Lower thermal stability due to thinning often leads to unprecedented hidden\nphases in low-dimensional materials. Such hidden phases can coexist or compete\nwith preexisting electronic phases. We investigate hidden phases observed in\natomically thin (6-8 layers) 1T-TaS$_2$ with scanning tunneling microscopy.\nFirst, we can electrically induce a hidden stripe phase at room temperature.\nSuch a uniaxial stripe phase has three equivalent orientations by breaking\nthree-fold symmetry of 1T-TaS$_2$. We also reveal that the hidden stripe phase\ncoexists with nearly commensurate charge-density-wave phase. Next, we observe\nthat the emergent stripe phase spontaneously appears without any electric\nexcitation on a tiny flake ($160\\times80$ nm$^2$). Our findings may provide a\nplausible explanation for the previously observed phase transition and two-fold\noptical response in thin 1T-TaS$_2$ devices at room temperature. Furthermore,\nthe hidden stripe phase would be crucial to understand exotic CDW-related\nphenomena in 1T-TaS$_2$ for potential applications.",
        "positive": "Thermal boundary resistance from transient nanocalorimetry: a multiscale\n  modeling approach: The Thermal Boundary Resistance at the interface between a nanosized Al film\nand an Al_{2}O_{3} substrate is investigated at an atomistic level. A room\ntemperature value of 1.4 m^{2}K/GW is found. The thermal dynamics occurring in\ntime-resolved thermo-reflectance experiments is then modelled via macro-physics\nequations upon insertion of the materials parameters obtained from atomistic\nsimulations. Electrons and phonons non-equilibrium and spatio-temporal\ntemperatures inhomo- geneities are found to persist up to the nanosecond time\nscale. These results question the validity of the commonly adopted lumped\nthermal capacitance model in interpreting transient nanocalorimetry\nexperiments. The strategy adopted in the literature to extract the Thermal\nBoundary Resistance from transient reflectivity traces is revised at the light\nof the present findings. The results are of relevance beyond the specific\nsystem, the physical picture being general and readily extendable to other\nheterojunctions."
    },
    {
        "anchor": "Transmission Line Impedance of Carbon Nanotube Thin Films for Chemical\n  Sensing: We measure the resistance and frequency-dependent gate capacitance of carbon\nnanotube (CNT) thin films in ambient, vacuum, and under low-pressure (10E-6\ntorr) analyte environments. We model the CNT film as an RC transmission line\nand show that changes in the measured capacitance as a function of gate bias\nand analyte pressure are consistent with changes in the transmission line\nimpedance due to changes in the CNT film resistivity alone; the electrostatic\ngate capacitance of the CNT film does not depend on gate voltage or chemical\nanalyte adsorption. However, the CNT film resistance is enormously sensitive to\nlow pressure analyte exposure.",
        "positive": "Probabilistic design of a molybdenum-base alloy using a neural network: An artificial intelligence tool is exploited to discover and characterize a\nnew molybdenum-base alloy that is the most likely to simultaneously satisfy\ntargets of cost, phase stability, precipitate content, yield stress, and\nhardness. Experimental testing demonstrates that the proposed alloy fulfils the\ncomputational predictions, and furthermore the physical properties exceed those\nof other commercially available Mo-base alloys for forging-die applications."
    },
    {
        "anchor": "Engineering the accurate distortion of an object's\n  temperature-distribution signature: It is up to now a challenge to control the conduction of heat. Here we\ndevelop a method to distort the temperature distribution signature of an object\nat will. As a result, the object accurately exhibits the same temperature\ndistribution signature as another object that is predetermined, but actually\ndoes not exist in the system. Our finite element simulations confirm the\ndesired effect for different objects with various geometries and compositions.\nThe underlying mechanism lies in the effects of thermal metamaterials designed\nby using this method. Our work is of value for applications in thermal\nengineering.",
        "positive": "Electric field control of magnetization dynamics in ZnMnSe/ZnBeSe\n  diluted-magnetic-semiconductor heterostructures: We show that the magnetization dynamics in diluted magnetic semiconductors\ncan be controlled separately from the static magnetization by means of an\nelectric field. The spin-lattice relaxation (SLR) time of magnetic Mn2+ ions\nwas tuned by two orders of magnitude by a gate voltage applied to n-type\nmodulation-doped (Zn,Mn)Se/(Zn,Be)Se quantum wells. The effect is based on\nproviding an additional channel for SLR by a two-dimensional electron gas\n(2DEG). The static magnetization responsible for the giant Zeeman spin\nsplitting of excitons was not influenced by the 2DEG density."
    },
    {
        "anchor": "A new palladium alloy with near-ideal hydrogen storage performance: Hydrogen-based fuels demand high-density storage that can operate under\nambient temperatures. Pd and its alloys are the most investigated metal\nhydrides for hydrogen fuel cell applications. This study presented an\nalternative Pd alloy for hydrogen storage that can store and release hydrogen\nat room temperature. The surface of the most studied Pd (110) was modified with\nAu and Rh so that the hydrogen adsorption energy was 0.49 eV and the release\ntemperature was 365 K. Both values are quite near to the optimum values for the\nadsorption energy and release temperature of a hydrogen fuel cell in real-world\nusage.",
        "positive": "Superior thermal conductivity and extremely high mechanical strength in\n  polyethylene chains from {\\it ab initio} calculation: The upper limit of the thermal conductivity and the mechanical strength are\npredicted for the polyethylene chain, by performing the {\\it ab initio}\ncalculation and applying the quantum mechanical non-equilibrium Green's\nfunction approach. Specially, there are two main findings from our calculation:\n(1). the thermal conductivity can reach a high value of 310 W/K/m in a 100 nm\npolyethylene chain at room temperature; (2). the Young's modulus in the\npolyethylene chain is as high as 374.5 GPa, and the polyethylene chain can\nsustain $32.85% \\pm 0.05%$ (ultimate) strain before undergoing structural phase\ntransition into gaseous ethylene."
    },
    {
        "anchor": "Substrate effect on the resistive switching in BiFeO3 thin films: BiFeO3 thin films have been deposited on Pt/sapphire and Pt/Ti/SiO2/Si\nsubstrates with pulsed laser deposition using the same growth conditions,\nrespectively. Au was sputtered as the top electrode. The microscopic structure\nof the thin film varies by changing the underlying substrate. Thin films on\nPt/sapphire are not resistively switchable due to the formation of Schottky\ncontacts at both the top and the bottom interface. However, thin films on\nPt/Ti/SiO2/Si exhibit an obvious resistive switching behavior under forward\nbias. The conduction mechanisms in BiFeO3 thin films on Pt/sapphire and\nPt/Ti/SiO2/Si substrates are discussed to understand the different resistive\nswitching behaviors.",
        "positive": "Electric field control of labyrinth domain structures in core-shell\n  ferroelectric nanoparticles: In the framework of the Landau-Ginzburg-Devonshire (LGD) approach, we studied\nthe possibility of controlling the polarity and chirality of equilibrium domain\nstructures by a homogeneous external electric field in a nanosized\nferroelectric core covered with an ultra-thin shell of screening charge. Under\ncertain screening lengths and core sizes, the minimum of the LGD energy, which\nconsists of Landau-Devonshire energy, Ginzburg polarization gradient energy,\nand electrostatic terms, leads to the spontaneous appearance of stable\nlabyrinth domain structures in the core. The labyrinths evolve from an initial\npolarization distribution consisting of arbitrarily small randomly oriented\nnanodomains. The equilibrium labyrinth structure is weakly influenced by\ndetails of the initial polarization distribution, such that one can obtain a\nquasi-continuum of nearly degenerate labyrinth structures, whose number is\nlimited only by the mesh discretization density. Applying a homogeneous\nelectric field to a nanoparticle with labyrinth domains, and subsequently\nremoving it, allows inducing changes to the labyrinth structure, as the maze\npolarity is controlled by a field projection on the particle polar axis. Under\nspecific conditions of the screening charge relaxation, the quasi-static\ndielectric susceptibility of the labyrinth structure can be negative,\npotentially leading to a negative capacitance effect. Considering the general\nvalidity of the LGD approach, we expect that an electric field control of\nlabyrinth domains is possible in many spatially-confined nanosized ferroics,\nwhich can be potentially interesting for advanced cryptography and modern\nnanoelectronics."
    },
    {
        "anchor": "Spin relaxation and spin Hall transport in 5d transition-metal ultrathin\n  films: The spin relaxation induced by the Elliott-Yafet mechanism and the extrinsic\nspin Hall conductivity due to the skew-scattering are investigated in 5d\ntransition-metal ultrathin films with self-adatom impurities as scatterers. The\nvalues of the Elliott-Yafet parameter and of the spin-flip relaxation rate\nreveal a correlation with each other that is in agreement with the Elliott\napproximation. At 10-layer thickness, the spin-flip relaxation time in 5d\ntransition-metal films is quantitatively reported about few hundred nanoseconds\nat atomic percent which is one and two orders of magnitude shorter than that in\nAu and Cu thin films, respectively. The anisotropy effect of the Elliott-Yafet\nparameter and of the spin-flip relaxation rate with respect to the direction of\nthe spin-quantization axis in relation to the crystallographic axes is also\nanalyzed. We find that the anisotropy of the spin-flip relaxation rate is\nenhanced due to the Rashba surface states on the Fermi surface, reaching values\nas high as 97% in 10-layer Hf(0001) film or 71% in 10-layer W(110) film.\nFinally, the spin Hall conductivity as well as the spin Hall angle due to the\nskew-scattering off self-adatom impurities are calculated using the Boltzmann\napproach. Our calculations employ a relativistic version of the\nfirst-principles full-potential Korringa-Kohn-Rostoker Green function method.",
        "positive": "Graphite creep negation during flash spark plasma sintering under\n  temperatures close to 2000$^\\circ$C: Graphite creep has high importance for applications using high pressures (100\nMPa) and temperatures close to 2000 {\\textdegree}C. In particular, the new\nflash spark plasma sintering process (FSPS) is highly sensitive to graphite\ncreep when applied to ultra-high temperature materials such as silicon carbide.\nIn this flash process taking only a few seconds, the graphite tooling reaches\ntemperatures higher than 2000 {\\textdegree}C resulting in its irreversible\ndeformation. The graphite tooling creep prevents the flash spark plasma\nsintering process from progressing further. In this study, a finite element\nmodel is used to determine FSPS tooling temperatures. In this context, we\nexplore the graphite creep onset for temperatures above 2000 {\\textdegree}C and\nfor high pressures. Knowing the graphite high temperature limit, we modify the\nFSPS process so that the sintering occurs outside the graphite creep range of\ntemperatures/pressures. 95 % dense silicon carbide compacts are obtained in\nabout 30 s using the optimized FSPS."
    },
    {
        "anchor": "Dynamic instability of individual carbon nanotube growth revealed by in\n  situ homodyne polarization microscopy: Understanding the kinetic selectivity of carbon nanotube growth at the scale\nof individual nanotubes is essential for the development of high chiral\nselectivity growth methods. Here we demonstrate that homodyne polarization\nmicroscopy can be used for high-throughput imaging of long individual carbon\nnanotubes under real growth conditions (at ambient pressure, on a substrate),\nand with sub-second time resolution. Our in situ observations on hundreds of\nindividual nanotubes reveal that about half of them grow at a constant rate all\nalong their lifetime while the other half exhibits stochastic changes in growth\nrates, and switches between growth, pause and shrinkage. Statistical analysis\nshows that the growth rate of a given nanotube essentially varies between two\nvalues, with similar average ratio (~1.7) regardless of whether the rate change\nis accompanied by a change in chirality. These switches indicate that the\nnanotube edge or the catalyst nanoparticle fluctuates between different\nconfigurations during growth.",
        "positive": "Direct STM Measurements of R- and H-type Twisted MoSe2/WSe2\n  Heterostructures: When semiconducting transition metal dichalcogenides heterostructures are\nstacked the twist angle and lattice mismatch leads to a periodic moir\\'e\npotential. As the angle between the layers changes, so do the electronic\nproperties. As the angle approaches 0- or 60-degrees interesting\ncharacteristics and properties such as modulations in the band edges, flat\nbands, and confinement are predicted to occur. Here we report scanning\ntunneling microscopy and spectroscopy measurements on the band gaps and band\nmodulations in MoSe2/WSe2 heterostructures with near 0 degree rotation (R-type)\nand near 60 degree rotation (H-type). We find a modulation of the band gap for\nboth stacking configurations with a larger modulation for R-type than for\nH-type as predicted by theory. Furthermore, local density of states images show\nthat electrons are localized differently at the valence band and conduction\nband edges."
    },
    {
        "anchor": "Spin-polarized Tunneling in Hybrid Metal-Semiconductor Magnetic Tunnel\n  Junctions: We demonstrate efficient spin-polarized tunneling between a ferromagnetic\nmetal and a ferromagnetic semiconductor with highly mismatched conductivities.\nThis is indicated by a large tunneling magnetoresistance (up to 30%) at low\ntemperatures in epitaxial magnetic tunnel junctions composed of a ferromagnetic\nmetal (MnAs) and a ferromagnetic semiconductor (GaMnAs) separated by a\nnonmagnetic semiconductor (AlAs). Analysis of the current-voltage\ncharacteristics yields detailed information about the asymmetric tunnel\nbarrier. The low temperature conductance-voltage characteristics show a zero\nbias anomaly and a V^1/2 dependence of the conductance, indicating a\ncorrelation gap in the density of states of GaMnAs. These experiments suggest\nthat MnAs/AlAs heterostructures offer well characterized tunnel junctions for\nhigh efficiency spin injection into GaAs.",
        "positive": "Influence of the Finite-size Effects on the Curie Temperature of\n  L10-FePt: We employ an atomistic model using a nearest-neighbor Heisenberg Hamiltonian\nexchange to study computationally the dependence of the Curie temperature of\nL10-FePt on finite-size and surface effects in Heat-assisted Magnetic Recording\n(HAMR) media. We demonstrate the existence of a size threshold at 3.5nm below\nwhich the impact of finite-size effects start to permeate into the center of\nthe grains and contribute to the reduction of the Curie temperature. We find a\ncorrelation between the Curie temperature and the percentage of atomistic bonds\nlost on the surface as a function of grain size, which can be extended to apply\nto not only L10-FePt but also generic magnetic systems of any crystal\nstructure. The investigation gives insight into finite-size effects which,\nbecause the inevitable grain size dispersion leads to an irreducible\ncontribution to a dispersion of the Curie temperature, has been predicted to be\na serious limitation of HAMR."
    },
    {
        "anchor": "Comment on \"Molecular dynamics study of the threshold displacement\n  energy in vanadium\": The simulation study on Frenkel pair creation in vanadium by L.A. Zepeda-Ruiz\net al. (Phys. Rev. B 67, 134114, 2003) is criticized for its lack of reference\nto existing experimental work and for generally inadequate treatment of\nliterature data. Hence, the validity of the ensuing discussion of various\nresults (e.g. the value of the minimum TDE and the Frenkel pair stability in V)\nis questioned.",
        "positive": "Depositing boron on Cu(111): Borophene or boride?: Large-area single-crystal surface structures were successfully prepared on\nCu(111) substrate with boron deposition, which is critical for prospective\napplications. However, the proposed borophene structures do not match the\nscanning tunneling microscopy (STM) results very well, while the proposed\ncopper boride is at odds with the traditional knowledge that ordered\ncopper-rich borides normally do not exist due to small difference in\nelectronegativity and large difference in atomic size. To clarify the\ncontroversy and elucidate the formation mechanism of the unexpected copper\nboride, we conducted systematic STM, X-ray photoelectron spectroscopy and\nangle-resolved photoemission spectroscopy investigations, confirming the\nsynthesis of two-dimensional copper boride rather than borophene on Cu(111)\nafter boron deposition under ultrahigh vacuum. First-principles calculations\nwith defective surface models further indicate that boron atoms tend to react\nwith Cu atoms near terrace edges or defects, which in turn shapes the\nintermediate structures of copper boride and leads to the formation of stable\nCu-B monolayer via large-scale surface reconstruction eventually."
    },
    {
        "anchor": "Probing the Relationship between Anisotropic Magnetoresistance and\n  Magnetization of ferromagnetic films: The anisotropic magnetoresistance (AMR) in thin permalloy strips was\ncalculated at each steps during magnetization by the finite element method. The\nmagnetization at equilibrium under different external fields was obtained by\nmicromagnetic simulations, while the resistance with different magnetization\nwas obtained by solving the Poisson equations iteratively until\nself-consistence. We find that the relation between magnetization and AMR\ndeviates from the Stoner-Wohlfarth prediction when the magnetization is reduced\nfrom saturation. The reason is that the demagnetization is not necessarily from\ncoherent rotation of the magnetic moment. We conclude that it is necessary to\nuse numeric simulations to optimize the responses of AMR sensors.",
        "positive": "Composition-dependent absorption of radiation in semiconducting MSi2Z4\n  Monolayers: The recent synthesis of MoSi2N4 material, along with theoretical predictions\nencompassing the entire family of chemical analogs, has opened up a new array\nof low-dimensional materials for a diverse range of optoelectronics and\nphotovoltaics applications. In this study, we conducted state-of-the-art\nmany-body first-principles calculations to analyze the quasi-particle\nelectronic structure of the material class MSi2Z4 (where M = Mo, W, and Z = N,\nP, As, Sb). All monolayers display a direct band gap at the K point, with the\nexception of MoSi2N4. In tungsten-based compounds, the fundamental-gap can be\nadjusted over a significantly broader energy range compared to their\nmolybdenum-based counterparts. Additionally, increasing atomic weight of the Z,\nboth the band gap and exciton binding energies decrease. A noteworthy feature\nis the absence of a lateral valley ({\\Lambda} or Q) near the conduction band\nminimum, indicating potential higher photoluminescence efficiencies compared to\nconventional transition-metal dichalcogenide monolayers. The optical spectra of\nthese materials are predominantly characterized by tightly bound excitons,\nleading to an absorption onset in the visible range (for N-based) and in the\ninfrared region (for others). This diversity offers promising opportunities to\nincorporate these materials and their heterostructures into optoelectronic\ndevices, with tandem solar cells being particularly promising."
    },
    {
        "anchor": "Charge-State Stability of Color Centers in Wide-Bandgap Semiconductors: The NV$^-$ color center in diamond has been extensively investigated for\nquantum sensing, computation, and communication applications. Nonetheless,\ncharge-state decay from the NV$^-$ to its neutral counterpart the NV$^0$\ndetrimentally affects the robustness of the NV$^-$ center and remains to be\nfully overcome. In this work, we provide an $ab~initio$ formalism for\naccurately estimating the rate of charge-state decay of color centers in\nwide-bandgap semiconductors. Our formalism employs density functional theory\ncalculations in the context of thermal equilibrium. We illustrate the method\nusing the transition of NV$^-$ to NV$^0$ in the presence of substitutional N\n[see Z. Yuan $et~al$., PRR 2, 033263 (2020)].",
        "positive": "Sublattice-selective inverse Faraday effect in ferrimagnetic rare-earth\n  iron garnet: We performed time-resolved pump--probe measurements using rare-earth iron\ngarnet \\ce{Gd3/2Yb1/2BiFe5O12} as a two-sublattice ferrimagnet. We measured the\ninitial phases of the magnetic resonance modes below and above the\nmagnetization compensation temperature to clarify the sublattice selectivity of\nthe inverse Faraday effect in ferrimagnets. A comparison of the time evolution\nof magnetization estimated using the equations of motion revealed that the\ninverse Faraday effect occurring in ferrimagnetic materials has sublattice\nselectivity. This is in striking contrast to antiferromagnets, in which the\ninverse Faraday effect acts on each sublattice identically. The initial phase\nanalysis can be applied to other ferrimagnets with compensation temperatures."
    },
    {
        "anchor": "High-pressure behavior of methylammonium lead iodide (MAPbI3) hybrid\n  perovskite: In this paper we provide an accurate high-pressure structural and optical\nstudy of MAPbI3 hybrid perovskite. Structural data show the presence of a phase\ntransition towards an orthorhombic structure around 0.3 GPa followed by full\namorphization of the system above 3 GPa. After releasing pressure the systems\nkeeps the high-pressure orthorhombic phase. The occurrence of these structural\ntransitions is further confirmed by pressure induced variations of the\nphotoluminescence signal at high pressure. These variations clearly indicate\nthat the bandgap value and the electronic structure of MAPI change across the\nphase transition.",
        "positive": "Deficiency of the Bulk Spin Hall Effect Model for Spin-Orbit Torques in\n  Magnetic Insulator/Heavy Metal Heterostructures: Electrical currents in a magnetic insulator/heavy metal heterostructure can\ninduce two simultaneous effects, namely, spin Hall magnetoresistance (SMR) on\nthe heavy metal side and spin-orbit torques (SOTs) on the magnetic insulator\nside. Within the framework of the pure spin current model based on the bulk\nspin Hall effect (SHE), the ratio of the spin Hall-induced anomalous Hall\neffect (SH-AHE) to SMR should be equal to the ratio of the field-like torque\n(FLT) to damping-like torque (DLT). We perform a quantitative study of SMR,\nSH-AHE, and SOTs in a series of thulium iron garnet/platinum or Tm3Fe5O12/Pt\nheterostructures with different Tm3Fe5O12 thicknesses, where Tm3Fe5O12 is a\nferrimagnetic insulator with perpendicular magnetic anisotropy. We find the\nratio between measured effective fields of FLT and DLT is at least 2 times\nlarger than the ratio of the SH-AHE to SMR. In addition, the bulk SHE model\ngrossly underestimates the spin torque efficiency of FLT. Our results reveal\ndeficiencies of the bulk SHE model and also address the importance of\ninterfacial effects such as the Rashba and magnetic proximity effects in\nmagnetic insulator/heavy metal heterostructures."
    },
    {
        "anchor": "Preventing the reconstruction of the polar discontinuity at oxide\n  heterointerfaces: Perovskite oxide heteroepitaxy receives much attention because of the\npossibility to com- bine the diverse functionalities of perovskite oxide\nbuilding blocks. A general boundary con- dition for the epitaxy is the presence\nof polar discontinuities at heterointerfaces. These polar discontinuities\nresult in reconstructions, often creating new functionalities at the interface.\nHowever, for a significant number of materials these reconstructions are\nunwanted as they alter the intrinsic materials properties at the interface.\nTherefore, a strategy to eliminate this reconstruction of the polar\ndiscontinuity at the interfaces is required. We show that the use of\ncompositional interface engineering can prevent the reconstruction at the\nLa0.67Sr0.33MnO3/SrTiO3 (LSMO/STO) interface. The polar discontinuity at this\ninterface can be removed by the insertion of a single La0.33Sr0.67O layer,\nresulting in improved interface magnetization and electrical conductivity.",
        "positive": "Origin of Large Dielectric Constant with Large Remnant Polarization and\n  Evidence of Magnetoelectric Coupling in Multiferroic La modified\n  BiFeO3-PbTiO3 Solid Solution: The presence of superlattice reflections and detailed analyses of the powder\nneutron and x-ray diffraction data reveal that La rich\n(BF$_{0.50}$-LF$_{0.50}$)$_{0.50}$-(PT)$_{0.50}$ (BF-LF-PT) has ferroelectric\nrhombohedral crystal structure with space group \\textit{$R3c$} at ambient\nconditions. The temperature dependence of lattice parameters, tilt angle,\ncalculated polarization $(P_{s})$, volume, and integrated intensity of\nsuperlattice and magnetic reflections show an anomaly around 170 K. Impedance\nspectroscopy, dielectric and ac conductivity measurements were performed in\ntemperature range $473K \\leq T \\leq 573K$ to probe the origin of large remnant\npolarization and frequency dependent broad transitions with large dielectric\nconstant near $T_c^{FE}$. Results of impedance spectroscopy measurements\nclearly show contributions of both grain and grain boundaries throughout the\nfrequency range ($10^{3}$ Hz$\\leq f\\leq 10^{7} $ Hz). It could be concluded\nthat the grain boundaries are more resistive and capacitive as compared to the\ngrains, resulting in inhomogeneities in the sample causing broad frequency\ndependent dielectric anomalies. Enhancement in dielectric constant and remnant\npolarization values are possibly due to space charge polarization caused by\npiling of charges at the interface of grains and grain boundaries. The\nimaginary parts of dielectric constant ($\\epsilon^{\\prime\\prime}$) Vs frequency\ndata were fitted using Maxwell-Wagner model at $T_c^{FE}(\\sim 523$K) and model\nfits very well with the data up to $10^{5}$ Hz. Magnetodielectric measurements\nprove that the sample starts exhibiting magnetoelectric coupling at $\\sim 170$\nK, which is also validated by neutron diffraction data."
    },
    {
        "anchor": "ReaxFF Reactive Force Field Development for Cu/Si Systems and\n  application to Copper Cluster Formation During Cu Diffusion Inside Silicon: Transition metal impurities such as nickel, copper, and iron, in solid-state\nmaterials like silicon have a significant impact on the electrical performance\nof integrated circuits and solar cells. To study the impact of copper\nimpurities inside bulk silicon on the electrical properties of the material,\none needs to understand the configurational space of copper atoms incorporated\ninside the silicon lattice. In this work, we performed ReaxFF reactive force\nfield based molecular dynamics simulations, studying different configurations\nof individual and crystalline copper atoms inside bulk silicon by looking at\nthe diffusional behavior of copper in silicon. The ReaxFF Cu/Si parameter set\nwas developed by training against DFT data, including the energy barrier for an\nindividual Cu-atom inside a silicon lattice. We found that the diffusion of\ncopper atoms has a direct relationship with the temperature. Moreover, it is\nalso shown that individual copper atoms start to clusterize inside bulk silicon\nat elevated temperatures. Our simulation results provide a comprehensive\npicture of the effects of temperature and copper concentration on the\ncrystallization of individual copper inside silicon lattice. Finally, the\nstress-strain relationship of Cu/Si compounds under uniaxial tensile loading\nhave been obtained. Our results indicate a decrease in the elastic modulus with\nincreasing level of Cu-impurity concentration. We observe spontaneous\nmicrocracking of the Si during the stress-strain tests as a consequence of the\nformation of a small Cu clusters adjacent to the Si surface.",
        "positive": "V2C MXene-modified g-C3N4 for enhanced visible-light photocatalytic\n  activity: Increasing the efficiency of charge transfer and separation efficiency of\nphotogenerated carriers are still the main challenges in the field of\nsemiconductor-based photocatalysts. Herein, we synthesized g-C3N4@V2C MXene\nphotocatalyst by modifying g-C3N4 using V2C MXene. The prepared photocatalyst\nexhibited outstanding photocatalytic performance under visible light. The\ndegradation efficiency of methyl orange by g-C3N4@V2C MXene photocatalyst was\nas high as 94.5%, which is 1.56 times higher than that by g-C3N4. This was\nattributed to the V2C MXene inhibiting the rapid recombination of\nphotogenerated carriers and facilitating rapid transfer of photogenerated\nelectrons (e) from g-C3N4 to MXene. Moreover, g-C3N4@V2C MXene photocatalyst\nshowed good cycling stability. The photocatalytic performance was higher than\n85% after three cycles. Experiments to capture free radicals revealed that\nsuperoxide radicals (02) are the main contributors to the photocatalytic\nactivity. Thus, the proposed g-C3N4@V2C MXene photocatalyst is a promising\nvisible-light catalyst."
    },
    {
        "anchor": "Magnetic properties of double exchange biased diluted magnetic\n  alloy/ferromagnet/antiferromagnet trilayers: The magnetic properties of trilayers consisting of a diluted magnetic alloy,\nCuMn (Cu0.99Mn0.01), a soft ferromagnet, Py(Ni0.8Fe0.2), and an\nantiferromagnet, alpha-Fe2O3, were investigated. The samples, grown by UHV\nmagnetron sputtering, were magnetically characterized in the temperature range\nT = 3-100 K. Typical exchange bias features, namely clear hysteresis cycle\nshifts and coercivity enhancements, were observed. Moreover the presence of an\ninverse bias, which had been already reported for spin glass-based structures,\nwas also obtained in a well defined range of temperatures and CuMn thicknesses.",
        "positive": "Network structure and dynamics of hydrogenated amorphous silicon: In this paper we discuss the application of current it ab initio computer\nsimulation techniques to hydrogenated amorphous silicon (a-Si:H). We begin by\ndiscussing thermal fluctuation in the number of coordination defects in the\nmaterial, and its temperature dependence. We connect this to the ``fluctuating\nbond center detachment\" mechanism for liberating H bonded to Si atoms. Next,\nfrom extended thermal MD simulation, we illustrate various mechanisms of H\nmotion. The dynamics of the lattice is then linked to the electrons, and we\npoint out that the squared electron-lattice coupling (and the thermally-induced\nmean square variation in electron energy eigenvalues) is robustly proportional\nto the localization of the conjugate state, if localization is measured with\ninverse participation ratio. Finally we discuss the Staebler-Wronski effect\nusing these methods, and argue that a sophisticated local heating picture\n(based upon reasonable calculations of the electron-lattice coupling and\nmolecular dynamic simulation) explains significant aspects of the phenomenon."
    },
    {
        "anchor": "Polarized Neutron Laue Diffraction on a Crystal Containing Dynamically\n  Polarized Proton Spins: We report on a polarized-neutron Laue diffraction experiment on a single\ncrystal of neodynium doped lanthanum magnesium nitrate hydrate containing\npolarized proton spins. By using dynamic nuclear polarization to polarize the\nproton spins, we demonstrate that the intensities of the Bragg peaks can be\nenhanced or diminished significantly, whilst the incoherent background, due to\nproton spin disorder, is reduced. It follows that the method offers unique\npossibilities to tune continuously the contrast of the Bragg reflections and\nthereby represents a new tool for increasing substantially the signal-to-noise\nratio in neutron diffraction patterns of hydrogenous matter.",
        "positive": "Static and Dynamic Disorder in Triple-Cation Hybrid Perovskites: A detailed understanding of the carrier dynamics and emission characteristics\nof organic-inorganic lead halide perovskites is critical for their\noptoelectronic and energy harvesting applications. In this work, we reveal the\nimpact of the crystal lattice disorder on the photo-generated electron-hole\npairs through low-temperature photoluminescence measurements. We provide strong\nevidence that the intrinsic disorder forms a sub-bandgap tail density of\nstates, which determines the emission properties at low temperature. The PL\nspectra indicate that the disorder evolves with increasing temperature,\nchanging its character from static to dynamic. This change is accompanied by a\nrapid drop of the PL efficiency, originating from the increased mobility of\nexcitons/polarons, which enables them to reach deep non-radiative recombination\ncenters more easily."
    },
    {
        "anchor": "Magnetism on Rough Surfaces of Fe, Co and Ni : An Augmented Space\n  Approach: The augmented space formalism coupled with the recursion method and a\ntight-binding linear Muffin-tin orbitals basis has been applied to study the\neffects of roughness on the properties of (001) surfaces of body-centered cubic\nFe and face-centered cubic Co and Ni. The formalism is also proposed for the\nstudy of smooth surface. Comparisons have been made for three types of\nsurfaces: a smooth surface, the surface with a rough top layer, and a more\nrealistic model with several rough top layers converging into a crystalline\nbulk. Comparisons have been made between the magnetic moments, work function\nand electronic density of states in the three models described above.",
        "positive": "Predicting the Structural, Electronic and Magnetic Properties of Few\n  Atomic-layer Polar Perovskite: Density functional theory (DFT) calculations are performed to predict the\nstructural, electronic and magnetic properties of electrically neutral or\ncharged few-atomic-layer (AL) oxides whose parent systems are based on polar\nperovskite $KTaO_{3}$. Their properties vary greatly with the number of ALs\n($n_{AL}$) and the stoichiometric ratio. In the few-AL limit ($n_{AL}\\leqslant\n14$), the even AL (EL) systems with chemical formula $(KTaO_{3})_{n}$ are\nsemiconductors, while the odd AL (OL) systems with formula\n($K_{n+1}Ta_{n}O_{3n+1}$ or $K_{n}Ta_{n+1}O_{3n+2}$) are half-metal except for\nthe unique $KTa_{2}O_{5}$ case which is a semiconductor due to the large\nPeierls distortions. After reaching certain critical thickness ($n_{AL}>14$),\nthe EL systems show ferromagnetic surface states, while ferromagnetism\ndisappears in the OL systems. These predictions from fundamental complexity of\npolar perovskite when approaching the two-dimensional (2D) limit may be helpful\nfor interpreting experimental observations later."
    },
    {
        "anchor": "First-Principles Ultrafast Exciton Dynamics and Time-Domain\n  Spectroscopies: Dark-Exciton Mediated Valley Depolarization in Monolayer\n  WSe$_2$: Calculations combining first-principles electron-phonon ($e$-ph) interactions\nwith the Boltzmann equation enable studies of ultrafast carrier and phonon\ndynamics. However, in materials with weak Coulomb screening, electrons and\nholes form bound excitons and their scattering processes become correlated,\nposing additional challenges for modeling nonequilibrium physics. Here we show\ncalculations of ultrafast exciton dynamics and related time-domain\nspectroscopies using $ab~initio$ exciton-phonon (ex-ph) interactions together\nwith an excitonic Boltzmann equation. Starting from the nonequilibrium exciton\npopulations, we develop simulations of time-domain absorption and photoemission\nspectra that take into account electron-hole correlations. We use this method\nto study monolayer WSe$_2$, where our calculations predict sub-picosecond\ntimescales for exciton relaxation and valley depolarization and reveal the key\nrole of intermediate dark excitons. The approach introduced in this work\nenables a quantitative description of nonequilibrium dynamics and ultrafast\nspectroscopies in materials with strongly bound excitons.",
        "positive": "Eshelbian dislocation mechanics: $J$-, $M$-, and $L$-integrals of\n  straight dislocations: In this work, using the framework of (three-dimensional) Eshelbian\ndislocation mechanics, we derive the $J$-, $M$-, and $L$-integrals of a single\n(edge and screw) dislocation in isotropic elasticity as a limit of the $J$-,\n$M$-, and $L$-integrals between two straight dislocations as they have recently\nbeen derived by Agiasofitou and Lazar [Int. J. Eng. Sci. 114 (2017) 16-40].\nSpecial attention is focused on the $M$-integral. The $M$-integral of a single\ndislocation in anisotropic elasticity is also derived. The obtained results\nreveal the physical interpretation of the $M$-integral (per unit length) of a\nsingle dislocation as the total energy of the dislocation which is the sum of\nthe self-energy (per unit length) of the dislocation and the dislocation core\nenergy (per unit length). The latter can be identified with the work produced\nby the Peach-Koehler force. It is shown that the dislocation core energy (per\nunit length) is twice the corresponding pre-logarithmic energy factor. This\nresult is valid in isotropic as well as in anisotropic elasticity. The only\ndifference lies on the pre-logarithmic energy factor which is more complex in\nanisotropic elasticity due to the anisotropic energy coefficient tensor which\ncaptures the anisotropy of the material."
    },
    {
        "anchor": "Controlled Growth of ZnO Nanowire, Nanowall, and Hybrid Nanostructures\n  on Graphene for Piezoelectric Nanogenerators: Precise control of morphologies of one-dimensional (1D) or 2D nanostructures\nduring growth has not been easily accessible, usually degrading the device\nperformance and therefore limiting applications to various advanced nanoscale\nelectronics and optoelectronics. Graphene could be a platform to serve as a\nsubstrate for both morphology control and direct use of electrodes due to its\nideal monolayer flatness with {\\pi} electrons. Here, we report that by using\ngraphene directly as a substrate, vertically well-aligned ZnO nanowires and\nnanowalls were obtained systematically by controlling Au catalyst thickness and\ngrowth time, without invoking significant thermal damage on the graphene layer\nduring thermal chemical vapor deposition of ZnO at high temperature of about\n900 oC. We further demonstrate a piezoelectric nanogenerator that was\nfabricated from the vertically aligned nanowire-nanowall ZnO hybrid/graphene\nstructure generates a new type of direct current.",
        "positive": "Comparing charge transfer tuning effects by chemical substitution and\n  uniaxial pressure in the organic charge transfer complex\n  tetramethoxypyrene-tetracyanoquinodimethane: In the search for novel organic charge transfer salts with variable charge\ntransfer degree we study the effects of two modifications to the recently\nsynthesized donor-acceptor Tetramethoxypyrene (TMP)-Tetracyanoquinodimethane\n(TCNQ). One is of chemical nature by substituting the acceptor TCNQ molecules\nby F4TCNQ molecules. The second consists in simulating the application of\nuniaxial pressure along the stacking axis of the system. In order to test the\nchemical substitution, we have grown single crystals of TMP-F4TCNQ and analyzed\nits electronic structure via electronic transport measurements, ab initio\ndensity functional theory (DFT) calculations and UV/VIS/IR absorption\nspectroscopy. This system shows an almost ideal geometrical overlap of nearly\nplanar molecules alternately stacked (mixed stack) and this arrangement is\nechoed by a semiconductor-like transport behavior with an increased\nconductivity along the stacking direction. This is in contrast to TMP-TCNQ\nwhich shows a less pronounced anisotropy and a smaller conductivity response.\nOur bandstructure calculations confirm the one-dimensional behavior of\nTMP-F4TCNQ with pro- nounced dispersion only along the stacking axis. Infrared\nmeasurements illustrating the CN vibration frequency shift in F4TCNQ suggest\nhowever no improvement on the degree of charge transfer in TMP-F4TCNQ with\nrespect to TMP-TCNQ. In both complexes about 0.1 is transferred from TMP to the\nacceptor. Concerning the pressure effect, our DFT calculations on designed\nTMP-TCNQ and TMP-F4TCNQ structures under different pressure conditions show\nthat application of uniaxial pressure along the stacking axis of TMP-TCNQ may\nbe the route to follow in order to obtain a much more pronounced charge\ntransfer."
    },
    {
        "anchor": "Quantum Oscillations of Elastic Moduli and Softening of Phonon Modes in\n  Metals: In this paper we present a theoretical analysis of the effect of\nmagnetostriction on quantum oscillations of elastic constants in metals under\nstrong magnetic fields.\n  It is shown that at low temperatures a significant softening of some acoustic\nmodes could occur near peaks of quantum oscillations of the electron density of\nstates (DOS) at the Fermi surface (FS). This effect is caused by a magnetic\ninstability of a special kind, and it can give rise to a lattice instability.\nWe also show that the most favorable conditions for this instability to be\nrevealed occur in metals whose Fermi surfaces include nearly cylindrical\nsegments.",
        "positive": "Towards hexagonal $C_{2v}$ systems with anisotropic DMI:\n  Characterization of epitaxial Co$(10\\bar{1}0)$/Pt$(110)$ multilayer films: Ferromagnet/heavy metal (FM/HM) multilayer thin films with $C_{2v}$ symmetry\nhave the potential to host antiskyrmions and other chiral spin textures via an\nanisotropic Dzyaloshinkii-Moriya interaction (DMI). Here, we present a\ncandidate material system that also has a strong uniaxial magnetocrystalline\nanisotropy aligned in the plane of the film. This system is based on a new\nCo/Pt epitaxial relationship, which is the central focus of this work:\nhexagonal closed-packed Co$(10\\bar{1}0)[0001]$ $\\parallel$ face-centered cubic\nPt$(110)[001]$. We characterized the crystal structure and magnetic properties\nof our films using X-ray diffraction techniques and magnetometry respectively,\nincluding q-scans to determine stacking fault densities and their correlation\nwith the measured magnetocrystalline anisotropy constant and thickness of Co.\nIn future ultrathin multilayer films, we expect this epitaxial relationship to\nfurther enable an anisotropic DMI while supporting interfacial perpendicular\nmagnetic anisotropy. The anticipated confluence of these properties, along with\nthe tunability of multilayer films, make this material system a promising\ntestbed for unveiling new spin configurations in FM/HM films."
    },
    {
        "anchor": "Raman evidence for nonadiabatic effects in optical phonon self-energies\n  of transition metals: We report a Raman study of the effect of temperature on the self-energies of\noptical phonons in a number of transition metals with hexagonal-close-packed\nstructure. Anisotropic softening of phonon energies and narrowing of phonon\nlinewidths with increasing temperature are observed. These effects are\nreproduced in the calculations of phonon spectral functions based on \\textit{ab\ninitio} electronic structures and with carrier scattering by phonons taken into\naccount. The combined observations and results of simulations indicate a\nrelation between observed anomalies and the renormalization of the electron\nspectrum due to electron-phonon interaction. It is emphasized that the\ntemperature dependence of the phonon energies resembles anharmonic behavior but\nis actually an electron-induced effect.",
        "positive": "Evidence for collective linear conduction in the Peierls conductor\n  o-TaS_3: Using photoconduction study we demonstrate that the low-temperature Ohmic\nconduction of TaS$_3$ is not provided by single-particle excitations --\nelectrons and holes excited over the Peierls gap. Instead, the low-temperature\nOhmic conduction is mostly provided by collective excitations having the\nactivation energy about half of the Peierls gap value and shunting the\ncontribution of electrons and holes."
    },
    {
        "anchor": "Blue photoluminescence from chemically derived graphene oxide: Fluorescent organic compounds are of significant importance to the\ndevelopment of low-cost opto-electronic devices. Blue fluorescence from\naromatic or olefinic molecules and their derivatives is particularly important\nfor display and lighting applications. Thin film deposition of\nlow-molecular-weight fluorescent organic compounds typically requires costly\nvacuum evaporation systems. On the other hand, solution-processable polymeric\ncounterparts generally luminesce at longer wavelengths due to larger\ndelocalization in the chain. Blue light emission from solution-processed\nmaterials is therefore of unique technological significance. Here we report\nnear-UV to blue photoluminescence (PL) from solution-processed graphene oxide\n(GO). The characteristics of the PL and its dependence on the reduction of GO\nindicates that it originates from the recombination of electron-hole (e-h)\npairs localized within small sp2 carbon clusters embedded within an sp3 matrix.\nThese results suggest that a sheet of graphene provides a parent structure on\nwhich fluorescent components can be chemically engineered without losing the\nmacroscopic structural integrity. Our findings offer a unique route towards\nsolution-processable opto-electronics devices with graphene.",
        "positive": "Bias dependence of tunneling magnetoresistance in magnetic tunnel\n  junctions with asymmetric barriers: The transport properties of magnetic tunnel junctions (MTJs) are very\nsensitive to interface modifications. In this work we investigate both\nexperimentally and theoretically the effect of asymmetric barrier modifications\non the bias dependence of tunneling magnetoresistance (TMR) in single crystal\nFe/MgO-based MTJs with (i) one crystalline and one rough interface and (ii)\nwith a monolayer of O deposited at the crystalline interface. In both cases we\nobserve an asymmetric bias dependence of TMR and a reversal of its sign at\nlarge bias. We propose a general model to explain the bias dependence in these\nand similar systems reported earlier. The model predicts the existence of two\ndistinct TMR regimes: (i) tunneling regime when the interface is modified with\nlayers of a different insulator and (ii) resonant regime when thin metallic\nlayers are inserted at the interface. We demonstrate that in the tunneling\nregime negative TMR is due to the high voltage which overcomes the exchange\nsplitting in the electrodes, while the asymmetric bias dependence of TMR is due\nto the interface transmission probabilities. In the resonant regime inversion\nof TMR could happen at zero voltage depending on the alignment of the resonance\nlevels with the Fermi surfaces of the electrodes. Moreover, the model predicts\na regime in which TMR has different sign at positive and negative bias\nsuggesting possibilities of combining memory with logic functions."
    },
    {
        "anchor": "Magnetodielectric coupling in a triangular Ising lattice: Dielectric constant measurement under magnetic field is an efficient\ntechnique to study the coupling between charges and spins in insulating\nmaterials. For magnetic oxides, the geometric frustration is known to be a key\ningredient to observe such a coupling. Measurements for the triangular\nIsing-like cobaltite Ca3Co2O6 have been made. Single crystals of Ca3Co2O6 are\nfound to exhibit a magnetodielectric effect below TN=25K with a peak in the\ne(H) curve at the ferri to ferromagnetic transition. This relation between e\nand magnetization has been modelized by using two order parameters in an energy\nexpansion derived from the Landau formalism and the fluctuation-dissipation\ntheorem. This result emphasizes the great potential of insulating transition\nmetal oxides for the search of magnetodielectric effect.",
        "positive": "Role of spin-orbit coupling and evolution of the electronic structure of\n  WTe$_2$ under an external magnetic field: Here, we present a detailed study on the temperature and angular dependence\nof the Shubnikov-de-Haas (SdH) effect in the semi-metal WTe$_2$. This compound\nwas recently shown to display a very large non-saturating magnetoresistance\nwhich was attributed to nearly perfectly compensated densities of electrons and\nholes. We observe four fundamental SdH frequencies and attribute them to\nspin-orbit split, electron- and hole-like, Fermi surface (FS) cross-sectional\nareas. Their angular dependence seems consistent with ellipsoidal FSs with\nvolumes suggesting a modest excess in the density of electrons with respect to\nthat of the holes. We show that density functional theory (DFT) calculations\nfail to correctly describe the FSs of WTe$_2$. When their cross-sectional areas\nare adjusted to reflect the experimental data, the resulting volumes of the\nelectron/hole FSs obtained from the DFT calculations would imply a pronounced\nimbalance between the densities of electrons and holes. We find evidence for\nfield-dependent Fermi surface cross-sectional areas by fitting the oscillatory\ncomponent superimposed onto the magnetoresistivity signal to several\nLifshitz-Kosevich components. We also observe a pronounced field-induced\nrenormalization of the effective masses. Taken together, our observations\nsuggest that the electronic structure of WTe$_2$ evolves with the magnetic\nfield. This evolution might be a factor contributing to its pronounced\nmagnetoresistivity."
    },
    {
        "anchor": "Carrier Diffusion in Thin-Film CH3NH3PbI3 Perovskite Measured using\n  Four-Wave Mixing: We report the application of femtosecond four-wave mixing (FWM) to the study\nof carrier transport in solution-processed CH3NH3PbI3. The diffusion\ncoefficient was extracted through direct detection of the lateral diffusion of\ncarriers utilizing the transient grating technique, coupled with simultaneous\nmeasurement of decay kinetics exploiting the versatility of the boxcar\nexcitation beam geometry. The observation of exponential decay of the transient\ngrating versus interpulse delay indicates diffusive transport with negligible\ntrapping within the first nanosecond following excitation. The in-plane\ntransport geometry in our experiments enabled the diffusion length to be\ncompared directly with the grain size, indicating that carriers move across\nmultiple grain boundaries prior to recombination. Our experiments illustrate\nthe broad utility of FWM spectroscopy for rapid characterization of macroscopic\nfilm transport properties.",
        "positive": "Domino plasmons for subwavelength terahertz circuitry: A new approach for the spatial and temporal modulation of electromagnetic\nfields at terahertz frequencies is presented. The waveguiding elements are\nbased on plasmonic and metamaterial notions and consist of an\neasy-to-manufacture periodic chain of metallic box-shaped elements protruding\nout of a metallic surface. It is shown that the dispersion relation of the\ncorresponding electromagnetic modes is rather insensitive to the waveguide\nwidth, preserving tight confinement and reasonable absorption loss even when\nthe waveguide transverse dimensions are well in the subwavelength regime. This\nproperty enables the simple implementation of key devices, such as tapers and\npower dividers. Additionally, directional couplers, waveguide bends, and ring\nresonators are characterized, demonstrating the flexibility of the proposed\nconcept and the prospects for terahertz applications requiring high integration\ndensity."
    },
    {
        "anchor": "Towards the grain boundary phonon scattering problem: an evidence for a\n  low-temperature crossover: The problem of phonon scattering by grain boundaries is studied within the\nwedge disclination dipole (WDD) model. It is shown that a specific q-dependence\nof the phonon mean free path for biaxial WDD results in a low-temperature\ncrossover of the thermal conductivity, $\\kappa$. The obtained results allow to\nexplain the experimentally observed deviation of $\\kappa$ from a $T^3$\ndependence below $0.1K$ in $LiF$ and $NaCl$.",
        "positive": "Multifunctional Oxides for Topological Magnetic Textures by Design: Several challenges in designing an operational Skyrmion racetrack memory are\nwell-known. Among those challenges, a few contradictions can be identified if\nresearchers were to rely only on metallic materials. Hence, expanding the\nexploration on Skyrmion Physics into oxide materials is essential to bridge the\ncontradicting gap. In this topical review, we first briefly revise the theories\nand criteria involved in stabilizing and manipulating Skymions, followed by\nstudying the behaviors of dipolar-stabilized magnetic bubbles. Next, we explore\nthe properties of multiferroic Skyrmions with magnetoelectric coupling, which\ncan only be stabilized in Cu$_2$OSeO$_3$ thus far, as well as the rare bulk\nN\\'eel-type Skyrmions in some polar materials. As an interlude section, we\nreview the theory of Anomalous (AHE) and Topological Hall Effect (THE), before\ngoing through the recent progress of THE in oxide thin films. The debate about\nan alternative interpretation is also discussed. Finally, this review ends with\nfuture outlooks about the promising strategies of using interfacial\ncharge-transfer and (111)-orientation of perovskites to benefit the field of\nSkyrmion research."
    },
    {
        "anchor": "Understanding the size effects on the electronic structure of ThO2\n  nanoparticles: Developing characterization techniques and analysis methods adapted to the\ninvestigation of nanoparticles (NPs) is of fundamental importance considering\nthe role of these materials in many fields of research. The study of actinide\nbased NPs, despite their environmental relevance, is still underdeveloped\ncompared to that of NPs based on stable and lighter elements. We present here\nan investigation of ThO2 NPs performed with High-Energy Resolution Fluorescence\nDetected (HERFD) X-ray Absorption Near-Edge Structure (XANES) and with ab\ninitio XANES simulations. The first post-edge feature of Th L3 edge HERFD XANES\ndisappears in small NPs and simulations considering non-relaxed structural\nmodels reproduce the trends observed in experimental data. Inspection of the\nsimulations from Th atoms in the core and on the surface of the NP indeed\ndemonstrates that the the first post-edge feature is very sensitive to the\nlowering of the number of coordinating atoms and therefore to the more exposed\nTh atoms at the surface of the NP. The sensitivity of the L3 edge HERFD XANES\nto low coordinated atoms at the surface stems from the hybridization of the\nd-Density of States (DOS) of Th with both O and Th neighboring atoms. This may\nbe a common feature to other oxide systems that can be exploited to investigate\nsurface interactions.",
        "positive": "Prediction of topological insulating behavior in Hg2CuTi-type Heusler\n  compounds from first principles: The topological band structures of the X2YZ Heusler compounds with the\nHg2CuTi structure are investigated by using first-principles calculations\nwithin density functional theory. Our results clearly show that a large number\nof the Hg2CuTi type Heusler compounds naturally exhibit distinct band-inversion\nfeature, which is mainly controlled by the Y-Z zinc blende sublattice. Similar\nto the half-Heusler family, the topological band order in Hg2CuTi type Heusler\ncompounds is sensitive to the variation of lattice constant, and most of them\npossess a negative formation energy, which makes them more suitable in material\ngrowth and could easily achieve the topological insulating behavior by alloying\nor proper strain."
    },
    {
        "anchor": "Prediction of new Group IV-V-VI monolayer semiconductors based on first\n  principle calculation: Two-dimension (2D) semiconductor materials have attracted much attention and\nresearch interest for their novel properties suitable for electronic and\noptoelectronic applications. In this paper, we have proposed an idea in new 2D\nmaterials design by using adjacent group elements to substitute half of the\natoms in the primitive configurations to form isoelectronic compounds. We have\nsuccessfully taken this idea on group V monolayers and have obtained many\nunexplored Group IV-V-VI monolayer compounds: P2SiS, As2SiS, As2GeSe, Sb2GeSe,\nSb2SnTe, and Bi2SnTe. Relative formation energy calculations, phonon spectrum\ncalculations, as well as finite-temperature molecular dynamics simulations\nconfirm their stability and DFT calculations indicate that they are all\nsemiconductors. This idea broadens the scope of group V semiconductors and we\nbelieve it can be extended to other type of 2D materials to obtain new\nsemiconductors with better properties for optoelectronic and electronic\napplications.",
        "positive": "Influence of the electrode nano/microstructure on the electrochemical\n  properties of graphite in aluminum batteries: Herein we report on a detailed investigation of the irreversible capacity in\nthe first cycle of pyrolytic graphite electrodes in aluminum batteries\nemploying 1-ethyl-3-methylimidazolium chloride:aluminum trichloride\n(EMIMCl:AlCl3) as electrolyte. The reaction mechanism, involving the\nintercalation of AlCl4 in graphite, has been fully characterized by correlating\nthe micro/nanostructural modification to the electrochemical performance. To\nachieve this aim a combination of X-ray diffraction (XRD), small angle X-ray\nscattering (SAXS) and computed tomography (CT) has been used. The reported\nresults evidence that the irreversibility is caused by a very large decrease in\nthe porosity, which consequently leads to microstructural changes resulting in\nthe trapping of ions in the graphite. A powerful characterization methodology\nis established, which can also be applied more generally to carbon-based\nenergy-related materials. Introduction"
    },
    {
        "anchor": "Surface optical Raman modes in InN nanostructures: Raman spectroscopic investigations are carried out on one-dimensional\nnanostructures of InN,such as nanowires and nanobelts synthesized by chemical\nvapor deposition. In addition to the optical phonons allowed by symmetry; A1,\nE1 and E2(high) modes, two additional Raman peaks are observed around 528 cm-1\nand 560 cm-1 for these nanostructures. Calculations for the frequencies of\nsurface optical (SO) phonon modes in InN nanostructures yield values close to\nthose of the new Raman modes. A possible reason for large intensities for SO\nmodes in these nanostructures is also discussed.",
        "positive": "Tuning the Magnetic and Electronic Properties of Monolayer VI3 by 3d\n  Transition Metal Doping: A First-Principles Study: Two-dimensional (2D) materials with robust magnetism have drawn immense\nattention for their promising applications in spintronics. Recently, intrinsic\nferromagnetic vanadium triiodide (VI3) has been synthesized experimentally. To\nenhance its spintronic property, we modified VI3 by interstitial doping with 3d\ntransition metals (TM) and used first-principles calculations to investigate\nthe geometric structure, formation energy, electronic property, and magnetism\nof pristine VI3 and 3d TM-doped VI3 monolayer. Among eight transition metal\n(Sc-, Ti-, V-, Cr-, Mn-, Fe-, Co-, and Ni-) doped VI3 materials, four of them\n(Ti-, V-, Mn-, and Ni-doped VI3) show robust magnetism with full spin\npolarization near the Fermi energy. Our research demonstrates that Ti-doped VI3\nresults in half-metallic semiconductor properties (HMS), while V-doped VI3 and\nNi-doped VI3 result in half-semiconductor properties (HSC). Surprisingly,\nMn-doped VI3 exhibits an unusual bipolar magnetic semiconductor property (BMS).\nThis unique combination of strong ferromagnetism and 100% spin polarization\nwith a half-metallic, half-semiconductor, or bipolar semiconductor property\nrenders 3d TM-doped VI3 as potential candidates for next generation\nsemiconductor spintronic applications. These spin-polarized materials will be\nextremely useful for spin-current generation and other spintronic applications."
    },
    {
        "anchor": "The Hawking-Unruh phenomenon on graphene: We find that, for a very specific shape of a monolayer graphene sample, a\ngeneral relativistic-like description of a back-ground spacetime for graphene's\nconductivity electrons is very natural. The corresponding electronic local\ndensity of states is of finite temperature. This is a Hawking-Unruh effect that\nwe propose to detect through an experiment with a Scanning Tunneling\nMicroscope.",
        "positive": "Temperature-dependent magnetocrystalline anisotropy of rare\n  earth/transition metal permanent magnets from first principles: The light\n  RCo$_5$ (R=Y, La-Gd) intermetallics: Computational design of more efficient rare earth/transition metal (RE-TM)\npermanent magnets requires accurately calculating the magnetocrystalline\nanisotropy (MCA) at finite temperature, since this property places an upper\nbound on the coercivity. Here, we present a first-principles methodology to\ncalculate the MCA of RE-TM magnets which fully accounts for the effects of\ntemperature on the underlying electrons. The itinerant electron TM magnetism is\ndescribed within the disordered local moment picture, and the localized RE-4f\nmagnetism is described within crystal field theory. We use our model, which is\nfree of adjustable parameters, to calculate the MCA of the RCo$_5$ (R=Y, La-Gd)\nmagnet family for temperatures 0--600 K. We correctly find a huge uniaxial\nanisotropy for SmCo$_5$ (21.3 MJm$^{-3}$ at 300 K) and two finite temperature\nspin reorientation transitions for NdCo$_5$. The calculations also demonstrate\ndramatic valency effects in CeCo$_5$ and PrCo$_5$. Our calculations provide\nquantitative, first-principles insight into several decades of RE-TM\nexperimental studies."
    },
    {
        "anchor": "Perpendicular magnetic anisotropy in Co$_2$Fe$_{0.4}$Mn$_{0.6}$Si: We report perpendicular magnetic anisotropy (PMA) in the half-metallic\nferromagnetic Heusler alloy Co$_2$Fe$_{0.4}$Mn$_{0.6}$Si (CFMS) in a\nMgO/CFMS/Pd trilayer stack. PMA is found for CFMS thicknesses between 1 and 2\nnm, with a magnetic anisotropy energy density of $K_U = 1.5\\times 10^6$\nerg/cm$^3$ for t$_{\\tiny \\textrm{CFMS}} = 1.5$ nm. Both the MgO and Pd layer\nare necessary to induce the PMA. We measure a tunable anomalous Hall effect,\nwhere its sign and magnitude vary with both the CFMS and Pd thickness.",
        "positive": "The role of adatoms for the adsorption of F4TCNQ on Au(111): Organic adlayers on inorganic substrates often contain adatoms, which can be\nincorporated within the adsorbed molecular species, forming two-dimensional\nmetal-organic frameworks at the substrate surface. The interplay between native\nadatoms and adsorbed molecules significantly changes various adlayer properties\nsuch as the adsorption geometry, the bond strength between the substrate and\nthe adsorbed species, or the work function at the interface. Here we use\ndispersion-corrected density functional theory to gain insight into the\nenergetics that drive the incorporation of native adatoms within molecular\nadlayers based on the prototypical, experimentally well-characterized system of\nF4TCNQ on Au(111). We explain the adatom-induced modifications in the\nadsorption geometry and the adsorption energy based on the electronic structure\nand charge transfer at the interface. With this, we provide deeper insight into\nthe general mechanisms causing the incorporation of adatoms within an adlayer\nmade of a strong acceptor molecular species."
    },
    {
        "anchor": "Competing s-p and p-p fluctuations in charge-disproportionation of\n  BaBiO3: Here we investigate the mechanism of charge-disproportionation (CD) in BaBiO3\n(BBO) using density functional theory under different crystal symmetries and by\nemploying strain as an external perturbation. The competition between Bi 6sp-O\n2p (s-p) and O 2p-O 2p (p-p) charge-fluctuations decides the electronic ground\nstate, charge-disproportionation and bond-disproportionation (BD) in BBO. An\nextended Hubbard Hamiltonian involving onsite (U) and long-range (V) coulomb\nrepulsions is also employed to ascertain the microscopic conditions for the\nformation of the lone-pair on bismuth site. A strong tensile strain increases\np-p fluctuation and enhances negative-charge transfer (CT) character, while\nstrong compressive strain favors s-p fluctuation leading to more positive-CT\ncharacter. Bulk BBO is at the verge of positive and negative-CT regimes.",
        "positive": "Remarkably high value of Capacitance in BiFeO3 Nanorod: A remarkably high value of specific capacitance of 450 F/g has been observed\nthrough electrochemical measurements in the electrode made of multiferroic\nBismuth Ferrite (BFO) in the form of nanorods protruding out. These BFO\nnanorods were developed on porous Anodised Alumina (AAO) templates using wet\nchemical technique. Diameters of nanorods were in the range of 20-100 nm. The\nhigh capacitance is attributed to the nanostructure. The active surface charge\nhas been evaluated electrochemically by cyclic voltammetry (CV) at different\nscanning rates and charge-discharge studies. The specific capacitances were\nconstant after several cycles of charge-discharge leading to their useful\napplication in devices. The mechanism of accumulation of charge on the\nelectrode surface has been studied."
    },
    {
        "anchor": "Spotlight on Charge-Transfer Excitons in Crystalline Textured n-Alkyl\n  Anilino Squaraine Thin Films: Prototypical n-alkyl terminated anilino squaraines for photovoltaic\napplications show characteristic double-hump absorption features peaking in the\ngreen and deep-red spectral range. These signatures result from coupling of an\nintramolecular Frenkel exciton and an intermolecular charge transfer exciton.\nCrystalline, textured thin films suitable for polarized spectro-microscopy have\nbeen obtained for compounds with n-hexyl (nHSQ) and n-octyl (nOSQ) terminal\nalkyl chains. The here released triclinic crystal structure of nOSQ is similar\nto the known nHSQ crystal structure. Consequently, crystallites from both\ncompounds show equal pronounced linear dichroism with two distinct polarization\ndirections. The difference in polarization angle between the two absorbance\nmaxima cannot be derived by spatial considerations from the crystal structure\nalone but requires theoretical modeling. Using an essential state model, the\nobserved polarization behavior was discovered to depend on the relative\ncontributions of the intramolecular Frenkel exciton and the intermolecular\ncharge transfer exciton to the total transition dipole moment. For both nHSQ\nand nOSQ, the contribution of the charge transfer exciton to the total\ntransition dipole moment was found to be small compared to the intramolecular\nFrenkel exciton. Therefore, the net transition dipole moment is largely\ndetermined by the intramolecular component resulting in a relatively small\nmutual difference between the polarization angles. Ultimately, the molecular\nalignment within the micro-textured crystallites can be deduced and, with that,\nthe excited state transitions can be spotted.",
        "positive": "Phase Stability of TiO$_2$ Polymorphs from Diffusion Quantum Monte Carlo: Titanium dioxide, TiO$_2$, has multiple applications in catalysis, energy\nconversion and memristive devices because of its electronic structure. Most of\nthese applications utilize the naturally existing phases: rutile, anatase and\nbrookite. Despite the simple form of TiO$_2$ and its wide uses, there is\nlong-standing disagreement between theory and experiment on the energetic\nordering of these phases that has never been resolved. We present the first\nanalysis of phase stability at zero temperature using the highly accurate\nmany-body fixed node diffusion Quantum Monte Carlo (QMC) method. We also\ninclude the effects of temperature by calculating the Helmholtz free energy\nincluding both internal energy and vibrational contributions from density\nfunctional perturbation theory based quasi harmonic phonon calculations. Our\nQMC calculations find that anatase is the most stable phase at zero\ntemperature, consistent with many previous mean-field calculations. However, at\nelevated temperatures, rutile becomes the most stable phase. For all finite\ntemperatures, brookite is always the least stable phase."
    },
    {
        "anchor": "Spin-split collinear antiferromagnets: a large-scale ab-initio study: It was recently discovered that, depending on their symmetries, collinear\nantiferromagnets can actually break the spin degeneracy in momentum space, even\nin the absence of spin-orbit coupling. Such systems, recently dubbed\naltermagnets, are signalled by the emergence of a spin-momentum texture set\nmainly by the crystal and magnetic structure, relativistic effects playing a\nsecondary role. Here we consider all collinear $q$=0 antiferromagnetic\ncompounds in the MAGNDATA database allowing for spin-split bands. Based on\ndensity-functional calculations for the experimentally reported crystal and\nmagnetic structures, we study more than sixty compounds and introduce numerical\nmeasures for the average momentum-space spin splitting. We highlight some\ncompounds that are of particular interest, either due to a relatively large\nspin splitting, such as CoF$_2$ and FeSO$_4$F, or because of their low-energy\nelectronic structure. The latter include LiFe$_2$F$_6$, which hosts nearly flat\nspin-split bands next to the Fermi energy, as well as RuO$_2$, CrNb$_4$S$_8$,\nand CrSb, which are spin-split antiferromagnetic metals.",
        "positive": "Radiative lifetime of free excitons in hexagonal boron nitride: Using a new time-resolved cathodoluminescence system dedicated to the UV\nspectral range, we present a first estimate of the radiative lifetime of free\nexcitons in hBN at room temperature. This is carried out from a single\nexperiment giving both the absolute luminescence intensity under continuous\nexcitation and the decay time of free excitons in the time domain. The\nradiative lifetime of indirect excitons in hBN is equal to 27 ns, which is much\nshorter than in other indirect bandgap semiconductors. This is explained by the\nclose proximity of the electron and the hole in the exciton complex, and also\nby the small energy difference between indirect and direct excitons. The\nunusually high luminescence efficiency of hBN for an indirect bandgap is\ntherefore semi-quantitatively understood."
    },
    {
        "anchor": "Structural change and phase coexistence upon magnetic ordering in the\n  magnetodielectric spinel Mn$_3$O$_4$: Cooperative Jahn-Teller ordering is well-known to drive the cubic\n$Fd\\overline{3}m$ to tetragonal $I$4$_1$/$amd$ structural distortion in\nMn$_3$O$_4$ at 1170 $^{\\circ}$C. Further structural distortion occurs in\nMn$_3$O$_4$ upon magnetic ordering at 42 K. Employing high-resolution\nvariable-temperature synchrotron x-ray diffraction we show that tetragonal\n$I$4$_1$/$amd$ and orthorhombic $Fddd$ phases coexist, with nearly equal\nfractions, below the N\\'eel temperature of Mn$_3$O$_4$. Significant variation\nof the orthorhombic $a$ and $b$ lattice constants from the tetragonal $a$\nlattice constant is observed. Structural phase coexistence in Mn$_3$O$_4$ is\nattributed to large strains due to the lattice mismatch between the tetragonal\n$I$4$_1$/$amd$ and the orthorhombic $Fddd$ phases. Strain tensors determined\nfrom Rietveld refinement show a highly strained matrix of the $I4_1/amd$ phase\nthat accommodates the nucleated orthorhombic $Fddd$ phase in the phase\ncoexistence regime. A comparison of the deformation observed in Mn$_3$O$_4$ to\nstructural deformations of other magnetic spinels shows that phase coexistence\nmay be a common theme when structural distortions occur below 50 K.",
        "positive": "Tetrahedra system Cudaca: high-temperature manifold of molecular\n  configurations governing low-temperature properties: The Cudaca system composed of isolated Cu2+ S=1/2 tetrahedra with\nantiferromagnetic exchange should exhibit properties of a frustrated quantum\nspin system. ab initio density functional theory calculations for electronic\nstructure and molecular dynamics computations suggest a complex interplay\nbetween magnetic exchange, electron delocalization and molecular vibrations.\nYet, extensive experimental characterization of Cudaca by means of synchrotron\nx-ray diffraction, magnetization, specific heat and inelastic neutron\nscattering reveal that properties of the real material can be only partly\nexplained by proposed theoretical models as the low temperature properties seem\nto be governed by a manifold of molecular configurations coexisting at high\ntemperatures."
    },
    {
        "anchor": "Size-dependence of anisotropic exchange interaction in InAs/GaAs quantum\n  dots: A comprehensive study of the exchange interaction between charge carriers in\nself-organized InAs/GaAs quantum dots is presented. Single quantum-dot\ncathodoluminescence spectra of quantum dots of different sizes are analyzed.\nSpecial attention is paid to the energetic structure of the charged excited\nexciton (hot trion). A varying degree of intermixing within the hot trion\nstates leads to varying degrees of polarization of the corresponding emission\nlines. The emission characteristics change from circularly polarized for small\nquantum dots to elliptically polarized for large quantum dots. The findings are\nexplained by a change of magnitude of the anisotropic exchange interaction and\ncompared to the related effect of fine-structure splitting in the neutral\nexciton and biexciton emission.",
        "positive": "Stable and Solution-Processable Cumulenic sp-Carbon Wires: A New\n  Paradigm for Organic Electronics: Solution-processed, large-area, and flexible electronics largely relies on\nthe excellent electronic properties of sp$^2$-hybridized carbon molecules,\neither in the form of $\\pi$-conjugated small molecules and polymers or graphene\nand carbon nanotubes. Carbon with sp-hybridization, the foundation of the\nelusive allotrope carbyne, offers vast opportunities for functionalized\nmolecules in the form of linear carbon atomic wires (CAWs), with intriguing and\neven superior predicted electronic properties. While CAWs represent a vibrant\nfield of research, to date, they have only been applied sparingly to molecular\ndevices. The recent observation of the field-effect in microcrystalline\ncumulenes suggests their potential applications in solution-processed thin-film\ntransistors but concerns surrounding the stability and electronic performance\nhave precluded developments in this direction. In the present study, ideal\nfield-effect characteristics are demonstrated for solution-processed thin films\nof tetraphenyl[3]cumulene, the shortest semiconducting CAW. Films are deposited\nthrough a scalable, large-area, meniscus-coating technique, providing\ntransistors with hole mobilities in excess of 0.1 cm$^2$ V$^{-1}$ s$^{-1}$, as\nwell as promising operational stability under dark conditions. These results\noffer a solid foundation for the exploitation of a vast class of molecular\nsemiconductors for organic electronics based on sp-hybridized carbon systems\nand create a previously unexplored paradigm."
    },
    {
        "anchor": "Bayesian optimization with active learning of Ta-Nb-Hf-Zr-Ti system for\n  spin transport properties: Designing materials with enhanced spin charge conversion, i.e., with high\nspin Hall conductivity (SHC) and low longitudinal electric conductivity (hence\nlarge spin Hall angle (SHA)), is a challenging task, especially in the presence\nof a vast chemical space for compositionally complex alloys (CCAs). In this\nwork, focusing on the Ta-Nb-Hf-Zr-Ti system, we confirm that CCAs exhibit\nsignificant spin Hall conductivities and propose a multi-objective Bayesian\noptimization approach (MOBO) incorporated with active learning (AL) in order to\nscreen for the optimal compositions with significant SHC and SHA. As a result,\nwithin less than 5 iterations we are able to target the TaZr-dominated systems\ndisplaying both high magnitudes of SHC (~-2.0 (10$^{-3}$ $\\Omega$ cm)$^{-1}$)\nand SHA (~0.03). The SHC is mainly ascribed to the extrinsic skew scattering\nmechanism. Our work provides an efficient route for identifying new materials\nwith significant SHE, which can be straightforwardly generalized to optimize\nother properties in a vast chemical space.",
        "positive": "Structure, strain, and control of ground state property in\n  LaTiO$_3$/LaAlO$_3$ superlattice: Using first-principles density functional theory calculations, we examined\nthe ground state property of LaTiO$_3$/LaAlO$_3$ superlattice. Total energy\ncalculations, taking account of the structural distortions, $U$ dependence, and\nexchange correlation functional dependence, show that the spin and orbital\nground state can be controlled systematically by the epitaxial strain. In the\nwide range of strains, ferromagnetic spin and antiferro orbital ordering are\nstabilized, which is notably different from the previously reported ground\nstate in titanate systems. By applying large tensile strains, the system can be\ntransformed into an antiferromagnetic spin and ferro-orbital-ordered phase."
    },
    {
        "anchor": "Partially-Bright Triplet Excitons in Perovskite Nanocrystals: Advances in opto-electronics require the development of materials with novel\nand engineered characteristics. A class of materials that has garnered\ntremendous interest is metal-halide perovskites, stimulated by meteoric\nincreases in photovoltaic efficiencies of perovskite solar cells. In addition,\nrecent advances have applied perovskite nanocrystals (NCs) in light-emitting\ndevices. It was discovered recently that, for cesium lead-halide perovskite\nNCs, their unusually efficient light-emission may be due to a unique excitonic\nfine-structure composed of three bright triplet states that minimally interact\nwith a proximal dark singlet state. To study this fine-structure without\nisolating single NCs, we use multi-dimensional coherent spectroscopy at\ncryogenic temperatures to reveal coherences involving triplet states of a\nCsPbI$_3$ NC ensemble. Picosecond timescale dephasing times are measured for\nboth triplet and inter-triplet coherences, from which we infer a unique exciton\nfine-structure level-ordering comprised of a dark state energetically\npositioned within the bright triplet manifold.",
        "positive": "Two-dimensional hole gas in organic semiconductors: A highly conductive metallic gas that is quantum mechanically confined at a\nsolid-state interface is an ideal platform to explore nontrivial electronic\nstates that are otherwise inaccessible in bulk materials. Although\ntwo-dimensional electron gas (2DEG) has been realized in conventional\nsemiconductor interfaces, examples of two-dimensional hole gas (2DHG), which is\nthe counter analogue of 2DEG, are still limited. Here, we report the\nobservation of a 2DHG in solution-processed organic semiconductors in\nconjunction with an electric double-layer using ionic liquids. A molecularly\nflat single crystal of high mobility organic semiconductors serves as a\ndefect-free interface that facilitates two-dimensional confinement of\nhigh-density holes. Remarkably low sheet resistance of 6 k$\\Omega$ and high\nhole gas density of 10$^{14}$ cm$^{-2}$ result in a metal-insulator transition\nat ambient pressure. The measured degenerated holes in the organic\nsemiconductors provide a broad opportunity to tailor low-dimensional electronic\nstates using molecularly engineered heterointerfaces."
    },
    {
        "anchor": "Apparatus for dosing liquid water in ultrahigh vacuum: The structure of the solid-liquid interface often defines function and\nperformance of materials in applications. To study the interface at the atomic\nscale, we extended an ultrahigh vacuum (UHV) surface-science chamber with an\napparatus that allows to bring a sample in contact with ultrapure liquid water\nwithout exposure to air. In this process, a sample, typically a single crystal\nprepared and characterized in UHV, is transferred into a separate, small\nchamber. This chamber already contains a volume of ultrapure water ice, whose\nvapor pressure is reduced to UHV range by cooling it to cryogenic temperatures.\nUpon warming, the ice melts and forms a liquid droplet, which is deposited on\nthe sample. First experiments carried out on rutile TiO2(110) single crystals\nusing this apparatus exhibit unprecedented purity, as tested by X-ray\nphotoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). These\nresults enabled to separate the effect of pure water from the effect of\nlow-level impurities present in the air. Other possible uses of the setup are\ndiscussed.",
        "positive": "Single-pulse all-optical switching in amorphous Dy$_x$Co$_{1-x}\\text{ }$\n  and Tb$_x$Co$_{1-x}$: Repeated uniform switching of the magnetization of thin films of\nferrimagnetic amorphous Gd$_{x}$(FeCo)$_{1-x}$ in response to single fast laser\npulses is well established. Here we report unusual toggle switching in thin\nfilms of sperimagnetic amorphous Dy$_x$Co$_{1-x}$ and Tb$_x$Co$_{1-x}$ with\n$\\it{x} \\simeq$ 0.25 irradiated with single 200 fs pulses of 800 nm laser\nlight. The samples have strong local random anisotropy due to the non-S state\nrare earth. The compensation temperature of the films is $\\le$ 180 K and their\nCurie temperature is $\\simeq$ 500 K. They are mostly switched by the first\npulse, and subsequent pulses lead to partial re-switching of a decreasing\namount of the irradiated area, with a granular structure of submicron regions\nof switched and unswitched material. Individual switched domains about 700 nm\nin size are observed around the edge of the irradiated spots where the fluence\nis at the threshold for switching. Results are discussed in terms of a random\nanisotropy model where the ratio of local anisotropy to exchange is temperature\ndependent and close to the threshold for strong pinning."
    },
    {
        "anchor": "Nickel Antidot Arrays on Anodic Alumina Substrates: Large area nickel antidot arrays with density up to 10^10 /cm^2 have been\nfabricated by depositing nickel onto anodic aluminum oxide membranes that\ncontain lattices of nanopores. Electron microscopy images show a high degree of\norder of the antidot arrays. Various sizes and shapes of the antidots were\nobserved with increasing thickness of the deposited nickel. New features appear\nin the antidot arrays in both magnetization and transport measurements when the\nexternal magnetic field is parallel to the current direction, including an\nenhancement and a nonmonotonous field dependence of the magnetoresistance,\nlarger values of the coercive field and remanence moment, and smaller\nsaturation field.",
        "positive": "Thermoelectric transport of GaAs, InP, and PbTe: Hybrid functional with\n  ${\\bf \\it k \\cdot p}$ interpolation versus scissor-corrected generalized\n  gradient approximation: Boltzmann transport calculations based on band structures generated with\ndensity functional theory (DFT) are often used in the discovery and analysis of\nthermoelectric materials. In standard implementations, such calculations\nrequire dense ${\\it k}$-point sampling of the Brillouin zone and are therefore\ntypically limited to the generalized gradient approximation (GGA), whereas more\naccurate methods such as hybrid functionals would have been preferable. GGA\nvariants, however, generally underestimate the band gap. While premature onset\nof minority carriers can be avoided with scissor corrections, the band gap also\naffects the band curvature. In this study, we resolved the ${\\it k}$-point\nsampling issue in hybrid-functional based calculations by extending our\nrecently developed ${\\it k}\\cdot\\tilde{{\\it p}}$ interpolation scheme [Comput.\nMater. Sci. 134, 17 (2017)] to non-local one-electron potentials and spin-orbit\ncoupling. The Seebeck coefficient generated based on hybrid functionals were\nfound to agree better than GGA with experimental data for GaAs, InP, and PbTe.\nFor PbTe, even the choice of hybrid functional has bearing on the\ninterpretation of experimental data, which we attribute to the description of\nvalley convergence of the valence band."
    },
    {
        "anchor": "Zener Tunneling in Semiconducting Nanotube and Graphene Nanoribbon p-n\n  Junctions: A theory is developed for interband tunneling in semiconducting carbon\nnanotube and graphene nanoribbon p-n junction diodes. Characteristic length and\nenergy scales that dictate the tunneling probabilities and currents are\nevaluated. By comparing the Zener tunneling processes in these structures to\ntraditional group IV and III-V semiconductors, it is proved that for identical\nbandgaps, carbon based 1D structures have higher tunneling probabilities. The\nhigh tunneling current magnitudes for 1D carbon structures suggest the distinct\nfeasibility of high-performance tunneling-based field-effect transistors.",
        "positive": "Softening Gradient Plasticity: Analytical Study of Localization under\n  Nonuniform Stress: Localization of plastic strain induced by softening can be objectively\ndescribed by a regularized plasticity model that postulates a dependence of the\ncurrent yield stress on a nonlocal softening variable defined by a differential\n(gradient) expression. This paper presents analytical solutions of the\none-dimensional localization problem under certain special nonuniform stress\ndistributions. The one-dimensional problem can be interpreted as describing\neither a tensile bar with variable cross section, or a beam subjected to a\nnonuniform bending moment. Explicit as well as implicit gradient formulations\nare considered. The evolution of the plastic strain profile and the shape of\nthe load-displacement diagram are investigated. It is shown that even if the\nlocal constitutive law exhibits softening right from the onset of yielding, the\nglobal load-displacement diagram has a hardening part. The interplay between\nthe internal length scales characterizing the material and the geometry is\ndiscussed."
    },
    {
        "anchor": "Impeding effect of cerium on the growth of helium bubble in iron: Our first-principles density functional theory calculations suggest that the\nrare earth element, Ce, has a stronger attraction (-1.31eV) to He than He-He\n(-1.18eV) in bcc Fe. Consequently, the mobile He atoms could be pinned to Ce,\nand hence a reduced merging of He clusters. Moreover, we find that the\nsegregated Ce layer at the He bubble surface presents an energy barrier of 0.33\neV to the upcoming He atom and thus slows down the bubble growth.",
        "positive": "Phonon dispersions and electronic structures of two-dimensional IV-V\n  compounds: One novel family of two-dimensional IV-V compounds have been proposed, whose\ndynamical stabilities and electronic properties have been systematically\ninvestigated using the density functional theory. Extending from our previous\nwork, two phases of carbon phosphorus bilayers \\alpha- and \\beta-C$_{2}$P$_{2}$\nhave been proposed. Both of them are dynamically stable and thermally stable at\n300K. They possess intrinsic HSE gaps of 2.70 eV and 2.67 eV, respectively.\nSimilar \\alpha- and \\beta-C$_{2}$Y$_{2}$ (Y= As, Sb, and Bi) can be obtained if\nthe phosphorus atoms in the \\alpha- and \\beta-C$_{2}$P$_{2}$ replaced by other\npnictogens, respectively. If the C atoms in the \\alpha- and\n\\beta-C$_{2}$Y$_{2}$ (Y= P, As, Sb, and Bi) are further replaced by other IV\nelements X (X=Si, Ge, Sn, and Pb), respectively, more derivatives of \\alpha-\nand \\beta-X$_{2}$Y$_{2}$ (Y=N, P, As, Sb, and Bi) also can be obtained. It was\nfound that the majority of them are dynamically stable. The proposed compounds\nrange from metal to insulators depending on their constitutions. All insulated\ncompounds can undergo a transition from insulator to metal induced by biaxial\nstrain. Some of them can undergo a transition from indirect band gap to direct\nband gap. These new compounds can become candidates as photovoltaic device,\nthermoelectric material field as well as lamellated superconductors."
    },
    {
        "anchor": "Raman Scattering Characterization and Electron Phonon Coupling Strength\n  for MeV implanted InP(111): Structural modifications in InP(111) due to 1.5 MeV implantation of Sb have\nbeen characterized using first order and second order Raman spectroscopy. With\nboth Longitudinal Optical (LO) and Transverse Optical (TO) modes allowed for\nInP(111), we have investigated the evolution of both these modes as a function\nof fluence. Intensity, linewidth and shifts of the phonons, for both first\norder and second order Raman modes, display the increase in damage in the\nlattice with increasing fluence. The results suggest that the presence of a\ncharge layer in the vicinity of the surface may be effecting the first order\nRaman data. A LO phonon-plasmon coupled mode, due to the charge layer, has also\nbeen observed that becomes sharper and more intense with increasing fluence.\nResults also show the presence of tensile stress along with the coexistence of\ncrystalline InP regions and amorphous zones in the lattice. Consequently phonon\nconfinement is observed. Phonon Confinement model (PCM) has been applied here\nto estimate the coherence length and the size of nano-crystalline zones in InP\nlattice after implantation. A crystalline/ amorphous (c/a) phase transition is\nobserved at the fluence of $1\\times10^{14} ions/cm^{2}$. The electron-phonon\ncoupling strength has been measured by utilizing the second order Raman modes.\nThis coupling strength is seen to decrease as the nano-crystalline zones, in\nthe implanted lattice, become smaller.",
        "positive": "Dirac Cones and Minigaps for Graphene on Ir(111): Epitaxial graphene on Ir(111) prepared in excellent structural quality is\ninvestigated by angle-resolved photoelectron spectroscopy. It clearly displays\na Dirac cone with the Dirac point shifted only slightly above the Fermi level.\nThe moire resulting from the overlaid graphene and Ir(111) surface lattices\nimposes a superperiodic potential giving rise to Dirac cone replicas and the\nopening of minigaps in the band structure."
    },
    {
        "anchor": "Thermodynamics and dielectric anomalies of DMAAS and DMAGaS crystals in\n  the phase transitions region (Landau theory approach): A simple description of thermodynamics of DMAAS and DMAGaS ferroelectric\ncrystals by means of Landau expansion is proposed. Conditions of occurrence of\nphase transitions are established and their temperatures are obtained. The\ninfluence of external hydrostatic pressure on phase transitions is described.\nThe temperature behaviour of dielectric susceptibility components and their\nanomalies in the vicinity of phase transition points are investigated. Obtained\nresults are compared with experimental data.",
        "positive": "Hydrogenation induced magnetic and electronic transitions in monolayer\n  electride Gd$_2$C: A first-principles study: The recently synthesized two-dimensional electride Gd$_2$C was proposed to be\na ferromagnetic metal that possesses multiple pairs of Weyl points and may\ndisplay a large anomalous Hall conductivity [Liu \\textit{et al.}, Phys. Rev.\nLett. \\textbf{125}, 187203 (2020)]. In view of its layered structure, here we\ncarry out first-principles studies on the magnetic and electronic properties of\nGd$_2$C in the ultrathin monolayer limit. We find that monolayer Gd$_2$C\nremains ferromagnetic like the bulk form and the hydrogenation can effectively\ntune its magnetism and electronic structure. With one-sided coverage of\nhydrogen atoms, monolayer Gd$_2$C becomes a half-metal with one spin channel\naround the Fermi level. For two-sided hydrogenation, monolayer Gd$_2$C\ntransforms to an antiferromagnetic insulator with a band gap of 0.8 eV. Our\nstudies show that monolayer electride Gd$_2$C can perform multiple magnetic and\nelectronic transitions with different levels of hydrogenation and may be also\nadopted to construct a planar heterojunction with selective area adsorption of\nhydrogen atoms, which has promising applications in future electronic and\nspintronic devices."
    },
    {
        "anchor": "Pulsed laser deposition of highly c-axis oriented thin films of BSTS\n  topological insulator: We report the growth of highly c-axis oriented topological insulator (TI)\nBiSbTe1.5Se1.5 (BSTS) thin films by pulsed laser deposition (PLD) technique.\nThe various growth parameters such as substrate temperature, Argon pressure in\nthe deposition chamber and target to substrate distance are tuned to obtain the\noptimized conditions essential for stoichiometric and bulk insulating TI thin\nfilms. These films are highly c-axis oriented and exhibit all the four Raman\nmodes characteristic to the R-3m space group. The quality of the deposited thin\nfilms is investigated using X-ray diffraction for crystallinity, Raman\nspectroscopy for lattice dynamics, morphological studies using scanning\nelectron microscope and compositional analysis using Energy dispersive X-ray\nspectroscopy. Resistance vs temperature measurements confirm bulk insulating\nnature of the prepared thin films and magnetoresistance data exhibits the\nphenomena of weak antilocalization with a large phase coherence length.",
        "positive": "Crystal Structure Generation Based on Polyhedra using Dual Periodic\n  Graphs: Crystal structure design is important for the discovery of new highly\nfunctional materials because crystal structure strongly influences material\nproperties. Crystal structures are composed of space-filling polyhedra, which\naffect material properties such as ionic conductivity and dielectric constant.\nHowever, most conventional methods of crystal structure prediction use random\nstructure generation methods that do not take space-filling polyhedra into\naccount, contributing to the inefficiency of materials development. In this\nwork, we propose a crystal structure generation method based on discrete\ngeometric analysis of polyhedra information. In our method, the shape and\nconnectivity of a space-filling polyhedron are represented as a dual periodic\ngraph, and the crystal structure is generated by the standard realization of\nthis graph. We demonstrate that this method can correctly generate\nface-centered cubic, hexagonal close-packed, and body-centered cubic structures\nfrom dual periodic graphs. This work is a first step toward generating\nundiscovered crystal structures based on the target polyhedra, leading to major\nadvances in materials design in areas including electronics and energy storage."
    },
    {
        "anchor": "Modeling Interlayer Interactions and Phonon Thermal Transport in\n  Silicene Bilayer: We develop an accurate interlayer pairwise potential derived from the\n\\textit{ab-initio} calculations and investigate the thermal transport of\nsilicene bilayers within the framework of equilibrium molecular dynamics\nsimulations. The electronic properties are found to be sensitive to the\ntemperature with the opening of the band gap in the $\\Gamma$$\\rightarrow$M\ndirection. The calculated phonon thermal conductivity of bilayer silicene is\nsurprisingly higher than that of monolayer silicene, contrary to the trends\nreported for other classes of 2D materials like graphene and hBN bilayers. This\ncounterintuitive behavior of the bilayer silicene is attributed to the\ninterlayer interaction effects and inherent buckling, which lead to a higher\ngroup velocity in the LA$_1$/LA$_2$ phonon modes. The thermal conductivity of\nboth the mono- and bilayer silicene decreases with temperature as $\\kappa\\sim\nT^{-0.9}$ because of the strong correlations between the characteristic\ntimescales of heat current autocorrelation function and temperature ($\\tau\\sim\nT^{-0.75}$). The mechanisms underlying phonon thermal transport in silicene\nbilayers are further established by analyzing the temperature induced changes\nin acoustic group velocity.",
        "positive": "New Tolerance Factor to Predict the Stability of Perovskite Oxides and\n  Halides: Predicting the stability of the perovskite structure remains a longstanding\nchallenge for the discovery of new functional materials for many applications\nincluding photovoltaics and electrocatalysts. We developed an accurate,\nphysically interpretable, and one-dimensional tolerance factor, {\\tau}, that\ncorrectly predicts 92% of compounds as perovskite or nonperovskite for an\nexperimental dataset of 576 $ABX_3$ materials ($\\textit{X} =$ $O^{2-}$, $F^-$,\n$Cl^-$, $Br^-$, $I^-$) using a novel data analytics approach based on SISSO\n(sure independence screening and sparsifying operator). {\\tau} is shown to\ngeneralize outside the training set for 1,034 experimentally realized single\nand double perovskites (91% accuracy) and is applied to identify 23,314 new\ndouble perovskites ($A_2$$\\textit{BB'}$$X_6$) ranked by their probability of\nbeing stable as perovskite. This work guides experimentalists and theorists\ntowards which perovskites are most likely to be successfully synthesized and\ndemonstrates an approach to descriptor identification that can be extended to\narbitrary applications beyond perovskite stability predictions."
    },
    {
        "anchor": "Phosphorene: Synthesis, Scale-up, and Quantitative Optical Spectroscopy: Phosphorene, a two-dimensional (2D) monolayer of black phosphorus, has\nattracted considerable theoretical interest, although the experimental\nrealization of monolayer, bilayer, and few-layer flakes has been a significant\nchallenge. Here we systematically survey conditions for liquid exfoliation to\nachieve the first large-scale production of monolayer, bilayer, and few-layer\nphosphorus, with exfoliation demonstrated at the 10-gram scale. We describe a\nrapid approach for quantifying the thickness of 2D phosphorus and show that\nmonolayer and few-layer flakes produced by our approach are crystalline and\nunoxidized, while air exposure leads to rapid oxidation and the production of\nacid. With large quantities of 2D phosphorus now available, we perform the\nfirst quantitative measurements of the material's absorption edge-which is\nnearly identical to the material's band gap under our experimental\nconditions-as a function of flake thickness. Our interpretation of the\nabsorbance spectrum relies on an analytical method introduced in this work,\nallowing the accurate determination of the absorption edge in polydisperse\nsamples of quantum-confined semiconductors. Using this method, we found that\nthe band gap of black phosphorus increased from 0.33 +/- 0.02 eV in bulk to\n1.88 +/- 0.24 eV in bilayers, a range that is larger than any other 2D\nmaterial. In addition, we quantified a higher-energy optical transition (VB-1\nto CB), which changes from 2.0 eV in bulk to 3.23 eV in bilayers. This work\ndescribes several methods for producing and analyzing 2D phosphorus while also\nyielding a class of 2D materials with unprecedented optoelectronic properties.",
        "positive": "Simulation for the oblique impact of a lattice system: The oblique collision between an elastic disk and an elastic wall is\nnumerically studied.\n  We investigate the dependency of the tangential coefficient of restitution on\nthe incident angle of impact.\n  From the results of simulation, our model reproduces experimental results and\ncan be explained by a phenomenological theory of the oblique impact."
    },
    {
        "anchor": "Ferromagnetic resonance study of free hole contribution to magnetization\n  and magnetic anisotropy in modulation-doped Ga$_{1 - x}$Mn$_{x}$As/Ga$_{1 -\n  y}$Al$_{y}$As:Be: Ferromagnetic resonance (FMR) is used to study magnetic anisotropy of GaMnAs\nin a series of Ga$_{1 - x}$Mn$_{x}$As/Ga$_{1 - y}$Al$_{y}$As heterostructures\nmodulation-doped by Be. The FMR experiments provide a direct measure of cubic\nand uniaxial magnetic anisotropy fields, and their dependence on the doping\nlevel. It is found that the increase in doping -- in addition to rising the\nCurie temperature of the Ga$_{1 - x}$Mn$_{x}$As layers -- also leads to a very\nsignificant increase of their uniaxial anisotropy field. The FMR measurements\nfurther show that the effective $g$-factor of Ga$_{1 - x}$Mn$_{x}$As is also\nstrongly affected by the doping. This in turn provides a direct measure of the\ncontribution from the free hole magnetization to the magnetization of Ga$_{1 -\nx}$Mn$_{x}$As system as a whole.",
        "positive": "Ultrashort Mn-Mn Bonds in Organometallic Complexes: Manganese metallocenes larger than the experimentally produced sandwiched\nMnBz$_2$ compound are studied using several density functional theory methods.\nFirst, we show that the lowest energy structures have Mn clusters surrounded by\nbenzene molecules, in so-called rice-ball structures. We then find a strikingly\nshort bond length of 1.8 {\\AA} between pairs of Mn atoms, accompanied by\nmagnetism depletion. The ultrashort bond lengths are related to Bz molecules\ncaging a pair of Mn atoms, leading to a Mn-Mn triple bond. This effect is also\nfound when replacing benzenes by other molecules such as borazine or\ncyclopentadiene. The stability of the Mn-Mn bond for Mn$_2$Bz$_2$ is further\ninvestigated using dissociation energy curves. For each spin configuration, the\nenergy versus distance plot shows different spin minima with barriers, which\nmust be overcome to synthesize larger Mn-Bz complexes."
    },
    {
        "anchor": "Anisotropic power diagrams for polycrystal modelling: efficient\n  generation of curved grains via optimal transport: The microstructure of metals and foams can be effectively modelled with\nanisotropic power diagrams (APDs), which provide control over the shape of\nindividual grains. One major obstacle to the wider adoption of APDs is the\ncomputational cost that is associated with their generation. We propose a novel\napproach to generate APDs with prescribed statistical properties, including\nfine control over the size of individual grains. To this end, we rely on fast\noptimal transport algorithms that stream well on Graphics Processing Units\n(GPU) and handle non-uniform, anisotropic distance functions. This allows us to\nfind APDs that best fit experimental data in (tens of) seconds, which unlocks\ntheir use for computational homogenisation. This is especially relevant to\nmachine learning methods that require the generation of large collections of\nrepresentative microstructures as training data. The paper is accompanied by a\nPython library, PyAPD, which is freely available at:\nwww.github.com/mbuze/PyAPD.",
        "positive": "Formation of nanostructures in ferroelectrics and antiferroelectrics in\n  the process of phase transformation: This paper contains results of investigations of inhomogeneous states caused\nby the coexistence of ferroelectric and antiferroelectric phases in\nlead-zirconate-titanate based solid solutions. The domains of ferroelectric and\nantiferroelectric phases with sizes of the order of 20 to 30 nm coexist in the\nbulk of the samples due to a small difference in the free energies of the\nphases. The coherent character of interphase boundaries leads to the\nconcentration of elastic stresses along these boundaries. Elastic stresses\ncause the local decomposition of the solid solution due to the circumstance\nthat equivalent positions of the crystal lattice are occupied by ions with\ndifferent sizes. Larger ions are driven out into domains with larger crystal\ncell parameters and smaller ions are pushed into domains with smaller\nparameters of the crystal cell. The sizes of segregates formed in this way are\nof the order 8 to 15 nm."
    },
    {
        "anchor": "Berry curvature dipole and nonlinear Hall effect in two-dimensional\n  Nb$_{2n+1}$Si$_n$Te$_{4n+2}$: Recent experiments have demonstrated interesting physics in a family of\ntwo-dimensional (2D) composition-tunable materials\nNb$_{2n+1}$Si$_n$Te$_{4n+2}$. Here, we show that owing to its intrinsic low\nsymmetry, metallic nature, tunable composition, and ambient stability, these\nmaterials offer a good platform for studying Berry curvature dipole (BCD) and\nnonlinear Hall effect. Using first-principles calculations, we find that BCD\nexhibits pronounced peaks in monolayer Nb$_{3}$SiTe$_{6}$ ($n=1$ case). Its\nmagnitude decreases monotonically with $n$ and completely vanishes in the\n$n\\rightarrow\\infty$ limit. This variation manifests a special hidden\ndimensional crossover of the low-energy electronic states in this system. The\nresulting nonlinear Hall response from BCD in these materials is discussed. Our\nwork reveals pronounced geometric quantities and nonlinear transport physics in\nNb$_{2n+1}$Si$_n$Te$_{4n+2}$ family materials, which should be readily detected\nin experiment.",
        "positive": "Pushing limits of photovoltaics and photodetection using radial junction\n  nanowire devices: Nanowire devices have long been proposed as an efficient alternative to their\nplanar counterparts for different optoelectronic applications. Unfortunately,\nchallenges related to the growth and characterization of doping and p-n\njunction formation in nanowire devices (along axial or radial axis) have\nsignificantly impeded their development. The problems are further amplified if\na p-n junction has to be implemented radially. Therefore, even though radial\njunction devices are expected to be on par with their axial junction\ncounterparts, there are minimal reports on high-performance radial junction\nnanowire optoelectronic devices. This paper summarizes our recent results on\nthe simulation and fabrication of radial junction nanowire solar cells and\nphotodetectors, which have shown unprecedented performance and clearly\ndemonstrate the importance of radial junction for optoelectronic applications.\nOur simulation results show that the proposed radial junction device is both\noptically and electrically optimal for solar cell and photodetector\napplications, especially if the absorber quality is extremely low. The radial\njunction nanowire solar cells could achieve a 17.2% efficiency, whereas the\nunbiased radial junction photodetector could show sensitivity down to a single\nphoton level using an absorber with a lifetime of less than 50 ps. In\ncomparison, the axial junction planar device made using same substrate as\nabsorber showed less than 1% solar cell efficiency and almost no photodetection\nat 0 V. This study is conclusive experimental proof of the superiority of\nradial junction nanowire devices over their thin film or axial junction\ncounterparts, especially when absorber lifetime is extremely low. The proposed\ndevice holds huge promise for III-V based photovoltaics and photodetectors."
    },
    {
        "anchor": "Phase transitions of LaMnO$_3$ and SrRuO$_3$ from DFT + U based machine\n  learning force fields simulations: Perovskite oxides are known to exhibit many magnetic, electronic and\nstructural phases as function of doping and temperature. These materials are\ntheoretically frequently investigated by the DFT+U method, typically in their\nground state structure at $T=0$. We show that by combining machine learning\nforce fields (MLFFs) and DFT+U based molecular dynamics, it becomes possible to\ninvestigate the crystal structure of complex oxides as function of temperature\nand $U$. Here, we apply this method to the magnetic transition metal compounds\nLaMnO$_3$ and SrRuO$_3$. We show that the structural phase transition from\northorhombic to cubic in LaMnO$_3$, which is accompanied by the suppression of\na Jahn-Teller distortion, can be simulated with an appropriate choice of $U$.\nFor SrRuO$_3$, we show that the sequence of orthorhombic to tetragonal to cubic\ncrystal phase transitions can be described with great accuracy. We propose that\nthe $U$ values that correctly capture the temperature-dependent structures of\nthese complex oxides, can be identified by comparison of the MLFF simulated and\nexperimentally determined structures.",
        "positive": "Advanced modeling of materials with PAOFLOW 2.0: New features and\n  software design: Recent research in materials science opens exciting perspectives to design\nnovel quantum materials and devices, but it calls for quantitative predictions\nof properties which are not accessible in standard first principles packages.\nPAOFLOW is a software tool that constructs tight-binding Hamiltonians from\nself-consistent electronic wavefunctions by projecting onto a set of atomic\norbitals. The electronic structure provides numerous materials properties that\notherwise would have to be calculated via phenomenological models. In this\npaper, we describe recent re-design of the code as well as the new features and\nimprovements in performance. In particular, we have implemented symmetry\noperations for unfolding equivalent k-points, which drastically reduces the\nruntime requirements of first principles calculations, and we have provided\ninternal routines of projections onto atomic orbitals enabling generation of\nreal space atomic orbitals. Moreover, we have included models for non-constant\nrelaxation time in electronic transport calculations, doubling the real space\ndimensions of the Hamiltonian as well as the construction of Hamiltonians\ndirectly from analytical models. Importantly, PAOFLOW has been now converted\ninto a Python package, and is streamlined for use directly within other Python\ncodes. The new object oriented design treats PAOFLOWs computational routines as\nclass methods, providing an API for explicit control of each calculation."
    },
    {
        "anchor": "Valley-polarization and stable triplet exciton formation in 2D lateral\n  heterostrcuture of hBN-kagome and graphene: Broken spatial inversion symmetry in semiconducting materials with\ntime-reversal pair valleys can exhibit valley polarization. Based on\nfirst-principles calculations, here we propose a lateral heterostructure of\nkagome lattice of hBN and hexagonal graphene domains that exhibits opposite\nBerry curvature in inequivalent K and K' valleys. Explicit consideration of\nexcitonic scattering processes within GW and Bethe-Salpeter equation formalism\nconfirm insignificant intervalley coupling and consequent valley polarization\nability along with 0.46 eV higher binding energy of triplet excitons. Such\nheterostructure with large charge carrier mobility can be exploited for\nadvanced valleytronic and optoelectronic applications.",
        "positive": "Critical probability of percolation over bounded region in N-dimensional\n  Euclidean space: Following H. Tomita and C. Murakami we propose an analytical model to predict\ncritical probability of percolation. It is based on the excursion set theory\nwhich allows us to consider N-dimensional bounded regions. Details are given\nfor the 3D case and statistically Representative Volume Elements are\ncalculated. Finally generalisation to the N-dimensional case is made."
    },
    {
        "anchor": "Spin-current mediated exchange coupling in MgO-based magnetic tunnel\n  junctions: Heterostructures composed of ferromagnetic layers that are mutually\ninteracting through a nonmagnetic spacer are at the core of magnetic sensor and\nmemory devices. In the present study, layer-resolved ferromagnetic resonance\nwas used to investigate the coupling between the magnetic layers of a\nCo/MgO/Permalloy magnetic tunnel junction. Two magnetic resonance peaks were\nobserved for both magnetic layers, as probed at the Co and Ni L3 x-ray\nabsorption edges, showing a strong interlayer interaction through the\ninsulating MgO barrier. A theoretical model based on the\nLandau-Lifshitz-Gilbert-Slonczewski equation was developed, including exchange\ncoupling and spin pumping between the magnetic layers. Fits to the experimental\ndata were carried out, both with and without a spin pumping term, and the\ngoodness of the fit was compared using a likelihood ratio test. This rigorous\nstatistical approach provides an unambiguous proof of the existence of\ninterlayer coupling mediated by spin pumping.",
        "positive": "Quick-start guide for first-principles modelling of semiconductor\n  interfaces: Interfaces between dissimilar materials control the transport of energy in a\nrange of technologies including solar cells (electron transport), batteries\n(ion transport), and thermoelectrics (heat transport). Advances in computer\npower and algorithms means that first-principles models of interfacial\nprocesses in realistic systems are now possible using accurate approaches such\nas density functional theory. In this `quick-start guide', we discuss the best\npractice in how to construct atomic models between two materials and analysis\ntechniques appropriate to probe changes in local bonding and electronic band\noffsets. A number of examples are given related to perovskite solar cells."
    },
    {
        "anchor": "Lattice dynamics and phase transition in CrI$_3$ single crystals: The vibrational properties of $\\mathrm{CrI_3}$ single crystals were\ninvestigated using Raman spectroscopy and were analyzed with respect to the\nchanges of the crystal structure. All but one mode are observed for both the\nlow-temperature $R\\bar{3}$ and the high-temperature C2/$m$ phase. For all\nobserved modes the energies and symmetries are in good agreement with DFT\ncalculations. The symmetry of a single-layer was identified as $p\\bar{3}1/m$.\nIn contrast to previous studies we observe the transition from the $R\\bar{3}$\nto the $\\mathrm{C2}/m$ phase at 180\\,K and find no evidence for coexistence of\nboth phases over a wide temperature range.",
        "positive": "Towards a Common Format for Computational Material Science Data: Information and data exchange is an important aspect of scientific progress.\nIn computational materials science, a prerequisite for smooth data exchange is\nstandardization, which means using agreed conventions for, e.g., units, zero\nbase lines, and file formats. There are two main strategies to achieve this\ngoal. One accepts the heterogeneous nature of the community which comprises\nscientists from physics, chemistry, bio-physics, and materials science, by\ncomplying with the diverse ecosystem of computer codes and thus develops\n\"converters\" for the input and output files of all important codes. These\nconverters then translate the data of all important codes into a standardized,\ncode-independent format. The other strategy is to provide standardized open\nlibraries that code developers can adopt for shaping their inputs, outputs, and\nrestart files, directly into the same code-independent format. We like to\nemphasize in this paper that these two strategies can and should be regarded as\ncomplementary, if not even synergetic. The main concepts and software\ndevelopments of both strategies are very much identical, and, obviously, both\napproaches should give the same final result. In this paper, we present the\nappropriate format and conventions that were agreed upon by two teams, the\nElectronic Structure Library (ESL) of CECAM and the NOMAD (NOvel MAterials\nDiscovery) Laboratory, a European Centre of Excellence (CoE). This discussion\nincludes also the definition of hierarchical metadata describing\nstate-of-the-art electronic-structure calculations."
    },
    {
        "anchor": "Magnetic Anisotropy of Deposited Transition Metal Clusters: We present results of magnetic torque calculations using the fully\nrelativistic spin-polarized Korringa-Kohn-Rostoker approach applied to small Co\nand Fe clusters deposited on the Pt(111) surface. From the magnetic torque one\ncan derive among others the magnetic anisotropy energy (MAE). It was found that\nthis approach is numerically much more stable and also computationally less\ndemanding than using the magnetic force theorem that allows to calculate the\nMAE directly. Although structural relaxation effects were not included our\nresults correspond reasonably well to recent experimental data.",
        "positive": "Detection of odor quality and ripening stage of Mangifera indica L. by\n  graphdiyne nanosheet -- a DFT outlook: Using first-principles calculation, geometrical stability together with\nelectronic properties of graphdiyne nanosheet (Gdn-NS) is investigated. The\nstructural stability of Gdn-NS is established with the support of phonon band\nstructure and cohesive energy. The main objective of the present study is to\ncheck the odor quality of Mangifera indica L. (mangoes) fruits during the\nvarious ripening stage with the influence of Gdn-NS material. In addition, the\nadsorption of various volatiles, namely ethyl butanoate, myrcene,\n(E,Z,Z)-1,3,4,8-undecatetraene and $\\gamma$-octalactone aromas on Gdn-NS is\nexplored with the significant parameters including Bader charge transfer,\nenergy gap, average energy gap changes and adsorption energy. The sensitivity\nof volatiles emitting from various ripening stages of mango on Gdn-NS were\nexplored with the influence of density of states spectrum. The outcomes of the\nproposed work help us to check the ripening stage and odor quality of Mangifera\nindica L. by Gdn-NS material using density functional theory."
    },
    {
        "anchor": "A study of singlet fission-halide perovskite interfaces: A method for improving the efficiency of solar cells is combining a\nlow-bandgap semiconductor with a singlet fission material (which converts one\nhigh energy singlet into two low energy triplets following photoexcitation).\nHere we present a study of the interface between singlet fission molecules and\nlow-bandgap halide pervoskites. We briefly show a range of experiments\nscreening for triplet transfer into a halide perovskite. However, in all cases\ntriplet transfer was not observed. This motivated us to understand the halide\nperovskite/singlet fission interface better by carrying out first-principles\ncalculations using tetracene and cesium lead iodide. We found that tetracene\nmolecules/thin films preferentially orient themselves parallel to/perpendicular\nto the halide perovskite's surface, in a similar way to on other inorganic\nsemiconductors. We present formation energies of all interfaces, which are\nsignificantly less favourable than for bulk tetracene, indicative of weak\ninteraction at the interface. It was not possible to calculate excitonic states\nat the full interface due to computational limitations, so we instead present\nhighly speculative toy interfaces between tetracene and a\nhalide-perovskite-like structure. In these models we focus on replicating\ntetracene's electronic states correctly. We find that tetracene's singlet and\ntriplet energies are comparable to that of bulk tetracene, and the triplet is\nstrongly localised on a single tetracene molecule, even at an interface. Our\nwork provides new understanding of the interface between tetracene and halide\nperovskites, explores the potential for modelling excitons at interfaces, and\nbegins to explain the difficulties in extracting triplets directly into\ninorganic semiconductors.",
        "positive": "Domain formation on oxidized graphene: Using first-principles calculations within density functional theory we\ndemonstrate that the adsorption of single oxygen atom results in significant\nelectron transfer from graphene to oxygen. This strongly disturbs the charge\nlandscape of the C-C bonds at the proximity. Additional oxygen atoms adsorbing\nto graphene prefer always the C-C bonds having highest charge density and\nconsequently they have tendency to form domain structure. While oxygen\nadsorption to one side of graphene ends with significant buckling, the\nadsorption to both sides with similar domain pattern is favored. The binding\nenergy displays an oscillatory variation and the band gap widens with\nincreasing oxygen coverage. While a single oxygen atom migrates over the C-C\nbonds on graphene surface, a repulsive interaction prevents two oxygen adatoms\nfrom forming an oxygen molecule. Our first-principles study together with\nfinite temperature ab-initio molecular dynamics calculations concludes that\noxygen adatoms on graphene cannot desorb easily without influence of external\nagents."
    },
    {
        "anchor": "Mirror Protected Multiple Nodal Line Semimetals and Material Realization: The conventional k.p method fails to capture the full and essential physics\nof many symmetry enriched multiple nodal line structures in the three\ndimensional Brillouin zone. Here we present a new and systematical method to\nconstruct the effective lattice model of mirror symmetry protected\nthree-dimensional multiple nodal line semimetals, when the spin-orbit\ninteraction is ignored. For systems with a given pair of perpendicular nodal\nrings, we obtain all the effective lattice models and eleven inequivalent nodal\nline Fermi surfaces together with their related constraints. By means of\nfirst-principles calculations, we first propose a family of real materials,\nbeta phase of ternary nitrides X2GeN2 (X = Ca; Sr; Ba), that support one kind\nof these novel Fermi surfaces. Therefore, our work deepens the understanding of\nthe nodal line structures and promotes the experimental progress of topological\nnodal line semimetals.",
        "positive": "Electronic Structure and Stability of the CH3NH3PbBr3 (001) Surface: The energetics and the electronic structure of methylammonium lead bromine\n(CH3NH3PbBr3) perovskite (001) surfaces are studied based on density functional\ntheory. By examining the surface grand potential, we predict that the\nCH3NH3Br-terminated (001) surface is energetically more favorable than the\nPbBr2-terminated (001) surface, under thermodynamic equilibrium conditions of\nbulk CH3NH3PbBr3. The electronic structure of each of these two different\nsurface terminations retains some of the characteristics of the bulk, while new\nsurface states are found near band edges which may affect the photovoltaic\nperformance in the solar cells based on CH3NH3PbBr3. The calculated electron\naffinity of CH3NH3PbBr3 reveals a sizable difference for the two surface\nterminations, indicating a possibility of tuning the band offset between the\nhalide perovskite and adjacent electrode with proper interface engineering."
    },
    {
        "anchor": "Electronic and optical properties of families of polycyclic aromatic\n  hydrocarbons: a systematic (time-dependent) density functional theory study: Homologous classes of Polycyclic Aromatic Hydrocarbons (PAHs) in their\ncrystalline state are among the most promising materials for organic\nopto-electronics. Following previous works on oligoacenes we present a\nsystematic comparative study of the electronic, optical, and transport\nproperties of oligoacenes, phenacenes, circumacenes, and oligorylenes. Using\ndensity functional theory (DFT) and time-dependent DFT we computed: (i)\nelectron affinities and first ionization energies; (ii) quasiparticle\ncorrection to the highest occupied molecular orbital (HOMO)-lowest unoccupied\nmolecular orbital (LUMO) gap; (iii) molecular reorganization energies; (iv)\nelectronic absorption spectra of neutral and $\\pm1$ charged systems. The\nexcitonic effects are estimated by comparing the optical gap and the\nquasiparticle corrected HOMO-LUMO energy gap. For each molecular property\ncomputed, general trends as a function of molecular size and charge state are\ndiscussed. Overall, we find that circumacenes have the best transport\nproperties, displaying a steeper decrease of the molecular reorganization\nenergy at increasing sizes, while oligorylenes are much more efficient in\nabsorbing low-energy photons in comparison to the other classes.",
        "positive": "Phase separation and frustrated square lattice magnetism of\n  Na1.5VOPO4F0.5: Crystal structure, electronic structure, and magnetic behavior of the\nspin-1/2 quantum magnet Na1.5VOPO4F0.5 are reported. The disorder of Na atoms\nleads to a sequence of structural phase transitions revealed by synchrotron\nx-ray powder diffraction and electron diffraction. The high-temperature\nsecond-order alpha <--> beta transition at 500 K is of the order-disorder type,\nwhereas the low-temperature beta <--> gamma+gamma' transition around 250 K is\nof the first order and leads to a phase separation toward the polymorphs with\nlong-range (gamma) and short-range (gamma') order of Na. Despite the complex\nstructural changes, the magnetic behavior of Na1.5VOPO4F0.5 probed by magnetic\nsusceptibility, heat capacity, and electron spin resonance measurements is well\ndescribed by the regular frustrated square lattice model of the\nhigh-temperature alpha-polymorph. The averaged nearest-neighbor and\nnext-nearest-neighbor couplings are J1 ~ -3.7 K and J2 ~ 6.6 K, respectively.\nNuclear magnetic resonance further reveals the long-range ordering below TN =\n2.6 K in low magnetic fields. Although the experimental data are consistent\nwith the simplified square-lattice description, band structure calculations\nsuggest that the ordering of Na atoms introduces a large number of inequivalent\nexchange couplings that split the square lattice into plaquettes. Additionally,\nthe direct connection between the vanadium polyhedra induces an unusually\nstrong interlayer coupling having effect on the transition entropy and the\ntransition anomaly in the specific heat. Peculiar features of the\nlow-temperature crystal structure and the relation to isostructural materials\nsuggest Na1.5VOPO4F0.5 as a parent compound for the experimental study of\ntetramerized square lattices as well as frustrated square lattices with\ndifferent values of spin."
    },
    {
        "anchor": "Photoluminescence and photochemistry of the $V_B^-$ defect in hexagonal\n  boron nitride: Extensive photochemical and spectroscopic properties of the $V_B^-$ defect in\nhexagonal boron nitride are calculated, concluding that the observed\nphotoemission associated with recently observed optically-detected magnetic\nresonance is most likely of (1)3E\" to (1)3A2' origin. Rapid intersystem\ncrossing from the defect's triplet to singlet manifolds explains the observed\nshort excited-state lifetime and very low quantum yield. New experimental\nresults reveal smaller intrinsic spectral bandwidths than previously\nrecognized, interpreted in terms spectral narrowing and zero-phonon-line\nshifting induced by the Jahn-Teller effect. Different types of computational\nmethods are applied to map out the complex triplet and singlet defect\nmanifolds, including the doubly ionised formulation of the equation-of-motion\ncoupled-cluster theory that is designed to deal with the open-shell nature of\ndefect states, and mixed quantum-mechanics/molecular-mechanics schemes enabling\n5763-atom simulations. Two other energetically feasible spectral assignments\nfrom amongst the singlet and triplet manifolds are considered, but ruled out\nbased on inappropriate photochemical properties.",
        "positive": "Spin crossover transition driven by pressure: Barocaloric applications: This article describes a mean-field theoretical model for Spin-Crossover\n(SCO) materials and explores its implications. It is based on a simple\nHamiltonian that yields the high spin molar fraction as a function of\ntemperature and pressure, as well as a temperature-pressure phase diagram for\nthe SCO transition. In order to test the model, we apply it to the giant\nBarocaloric Effect (BCE) of the SCO material [FeL$_2$][BF$_4$]$_2$ and\ncomprehensively analyse its behavior. We found that optical phonons are\nresponsible for 92\\% of the total barocaloric entropy change. DFT calculations\nshow that these optical phonons are mainly assigned to the low frequencies\nmodes of vibration ($<400$ cm$^{-1}$), being associated to the Fe coordination."
    },
    {
        "anchor": "Thermal and mechanical stability of zeolitic imidazolate frameworks\n  polymorphs: Theoretical studies on the experimental feasibility of hypothetical Zeolitic\nImidazolate Frameworks (ZIF) have focused so far on relative energy of various\npolymorphs, by energy minimization at the quantum chemical level. We present\nhere a systematic study of stability of 18 ZIFs as a function of temperature\nand pressure, by molecular dynamics simulations. This approach allows us to\nbetter understand the limited stability of some experimental structures upon\nsolvent or guest removal. We also find that many of the hypothetical ZIFs\nproposed in the literature are not stable at room temperature. Mechanical and\nthermal stability criteria thus need to be considered for the prediction of new\nMOF structures. Finally, we predict a variety of thermal expansion behavior for\nZIFs as a function of framework topology, with some materials showing large\nnegative volume thermal expansion.",
        "positive": "High Mobility Two-Dimensional Electron Gas at the\n  BaSnO$_{3}$/SrNbO$_{3}$ Interface: Oxide two-dimensional electron gases (2DEGs) promise high charge carrier\nconcentrations and low-loss electronic transport in semiconductors such as\nBaSnO$_{3}$ (BSO). ACBN0 computations for BSO/SrNbO$_{3}$ (SNO) interfaces show\nNb-4$\\textit{d}$ electron injection into extended Sn-5$\\textit{s}$ electronic\nstates. The conduction band minimum consists of Sn-5$\\textit{s}$ states ~1.2 eV\nbelow the Fermi level for intermediate thickness 6-unit cell BSO/6-unit cell\nSNO superlattices, corresponding to an electron density in BSO of ~10$^{21}$\ncm$^{-3}$. Experimental studies of analogous SNO/BSO interfaces grown by\nmolecular beam epitaxy confirm significant charge transfer from SNO to BSO.\n$\\textit {In situ}$ angle-resolved X-ray photoelectron spectroscopy studies\nshow an electron density of ~4 $\\times$ 10$^{21}$ cm$^{-3}$. The consistency of\ntheory and experiment shows that BSO/SNO interfaces provide a novel materials\nplatform for low loss electron transport in 2DEGs."
    },
    {
        "anchor": "Degenerate transition pathways for screw dislocations: implications for\n  migration: In body-centred-cubic (bcc) metals migrating 1/2<111> screw dislocations\nexperience a periodic energy landscape with a triangular symmetry. Atomistic\nsimulations, such as those performed using the nudged-elastic-band (NEB)\nmethod, generally predict a transition-pathway energy-barrier with a\ndouble-hump; contradicting Ab Initio findings. Examining the trajectories\npredicted by NEB for a particle in a Peierls energy landscape representative of\nthat obtained for a screw dislocation, reveals an unphysical anomaly caused by\nthe occurrence of monkey saddles in the landscape. The implications for motion\nof screws with and without stress are discussed.",
        "positive": "Electron doping of proposed quantum spin liquid kagom\u00e9 Zn-Cu\n  hydroxyl-halides produces localized states in the band gap: Carrier doping of quantum spin liquids is a long-proposed route to the\nemergence of high-temperature superconductivity. Electrochemical intercalation\nin kagome hydroxyl-halide materials shows that samples remain insulating across\na wide range of electron counts. Here we demonstrate through first-principles\ndensity functional calculations corrected for self-interaction the mechanism by\nwhich electrons remain localized in various Zn-Cu hydroxyl-halides,\nindependently of the chemical identity of the dopant - the formation of\npolaronic states with attendant lattice displacements and a dramatic narrowing\nof bandwidth upon electron addition. The same theoretical method applied to\nelectron doping in cuprate Nd2CuO4 correctly produces a metallic state when the\ninitially formed polaron dissolves into an extended state. Our general findings\nexplain the insulating behavior in a wide range of doped quantum magnets and\ndemonstrate that new quantum spin liquid host materials are needed to realize\nmetallicity borne of a spin liquid."
    },
    {
        "anchor": "Near-Room-Temperature Ferromagnetic Behavior of Single-Atom-Thick 2D\n  Iron in Nanolaminated Ternary MAX Phases: Two dimensional (2D) ferromagnetic materials have attracted much attention in\nthe fields of condensed matter physics and materials science, but their\nsynthesis is still a challenge given their limitations on structural stability\nand susceptibility to oxidization. MAX phases nanolaminated ternary carbides or\nnitrides possess a unique crystal structure in which single-atom-thick A\nsublayers are interleaved by two dimensional MX slabs, providing nanostructured\ntemplates for designing 2D ferromagnetic materials if the non-magnetic A\nsublayers can be substituted replaced by magnetic elements. Here, we report\nthree new ternary magnetic MAX phases (Ta2FeC, Ti2FeN and Nb2FeC) with A\nsublayers of single-atom-thick 2D iron through an isomorphous replacement\nreaction of MAX precursors (Ta2AlC, Ti2AlN and Nb2AlC) with a Lewis acid salts\n(FeCl2). All these MAX phases exhibit ferromagnetic (FM) behavior. The Curie\ntemperature (Tc) of Ta2FeC and Nb2FeC MAX phase are 281 K and 291 K,\nrespectively, i.e. close to room temperature. The saturation magnetization of\nthese ternary magnetic MAX phases is almost two orders of magnitude higher than\nthat of V2(Sn,Fe)C MAX phase whose A-site is partial substituted by Fe.\nTheoretical calculations on magnetic orderings of spin moments of Fe atoms in\nthese nanolaminated magnetic MAX phases reveal that the magnetism can be mainly\nascribed to intralayer exchange interaction of the 2D Fe atomic layers. Owning\nto the richness in composition of MAX phases, there is a large compositional\nspace for constructing functional single-atom-thick 2D layers in materials\nusing these nanolaminated templates.",
        "positive": "Miniature capacitive Faraday force magnetometer for magnetization\n  measurements at low temperatures and high magnetic fields: A Faraday force magnetometer is presented for measurements of magnetization\nat temperatures down to 100~mK and in magnetic fields up to 14~T. The specimen\nis mounted on a flexible cantilever forming a force-sensing capacitor in\ncombination with a fixed back plate. Two different cantilever designs are\npresented. A torsion resistant cantilever allows to measure magnetization of\nhighly anisotropic single crystal samples. Measurements of the metal organic\nquantum magnets (C$_5$H$_{12}$N)$_2$CuBr$_4$ (BPCB) and NiCl$_2$$\\cdot$4\nSC(NH$_2$)$_2$ (DTN) demonstrate the device's capabilities. Routinely, a\nspecimen's magnetic moment is measured with a resolution better than $10^{-7}$\nA$\\,$m$^2$ ($10^{-4}$ emu). The device in miniaturized to fit is almost any\ncryostat."
    },
    {
        "anchor": "Surface spin polarization of the non-stoichiometric Heusler compound\n  Co2Mn(alpha)Si: Using a combined approach of spin-resolved photoemission spectroscopy, band\nstructure and photoemission calculations we investigate the influence of bulk\ndefects and surface states on the spin polarization of Co2Mn(alpha)Si thin\nfilms with bulk L21 order. We find that for Mn-poor alloys the spin\npolarization at EF is negative due to the presence of Co_Mn antisite and\nminority surface state contributions. In Mn-rich alloys, the suppression of\nCo(Mn) antisites leads to a positive spin polarization at the Fermi energy, and\nthe influence of minority surface states on the photoelectron spin polarization\nis reduced.",
        "positive": "Low Thermal Budget High-k/Metal Surface Gate for Buried Donor-Based\n  Devices: Atomic precision advanced manufacturing (APAM) offers creation of donor\ndevices in an atomically thin layer doped beyond the solid solubility limit,\nenabling unique device physics. This presents an opportunity to use APAM as a\npathfinding platform to investigate digital electronics at the atomic limit.\nScaling to smaller transistors is increasingly difficult and expensive,\nnecessitating the investigation of alternative fabrication paths that extend to\nthe atomic scale. APAM donor devices can be created using a scanning tunneling\nmicroscope (STM). However, these devices are not currently compatible with\nindustry standard fabrication processes. There exists a tradeoff between low\nthermal budget (LT) processes to limit dopant diffusion and high thermal budget\n(HT) processes to grow defect-free layers of epitaxial Si and gate oxide. To\nthis end, we have developed an LT epitaxial Si cap and LT deposited Al2O3 gate\noxide integrated with an atomically precise single-electron transistor (SET)\nthat we use as an electrometer to characterize the quality of the gate stack.\nThe surface-gated SET exhibits the expected Coulomb blockade behavior. However,\nthe leverage of the gate over the SET is limited by defects in the layers above\nthe SET, including interfaces between the Si and oxide, and structural and\nchemical defects in the Si cap. We propose a more sophisticated gate stack and\nprocess flow that is predicted to improve performance in future atomic\nprecision devices."
    },
    {
        "anchor": "Folding a 2-D powder diffraction image into a 1-D scan: a new procedure: A new procedure aiming at folding a powder diffraction 2-D into a 1-D scan is\npresented. The technique consists of three steps: tracking the beam centre by\nmeans of a Simulated Annealing (SA) of the diffraction rings along the same\naxis, detector tilt and rotation determination by a Hankel Lanczos Singular\nValue Decomposition (HLSVD) and intensity integration by an adaptive binning\nalgorithm. The X-ray powder diffraction (XRPD) intensity profile of the\nstandard NIST Si 640c sample is used to test the performances. Results show the\nrobustness of the method and its capability of efficiently tagging the pixels\nin a 2-D readout system by matching the ideal geometry of the detector to the\nreal beam-sample-detector frame. The whole technique turns out in a versatile\nand user-friendly tool for the $2\\vartheta$ scanning of 2-D XRPD profiles.",
        "positive": "Rational design of large anomalous Nernst effect in Dirac semimetals: Anomalous Nernst effect generates a transverse voltage perpendicular to the\ntemperature gradient. It has several advantages compared with the longitudinal\nthermoelectricity for energy conversion, such as decoupling of electronic and\nthermal transports, higher flexibility, and simpler lateral structure. However,\na design principle beyond specific materials systems for obtaining a large\nanomalous Nernst conductivity (ANC) is still absent. In this work, we\ntheoretically demonstrate that a pair of Dirac nodes under a Zeeman field\nmanifests a double-peak anomalous Hall conductivity curve with respect to the\nchemical potential and a compensated carriers feature, leading to an enhanced\nANC pinning at the Fermi level compared with that of a simple Weyl semimetal\nwith two Weyl nodes. Based on first-principles calculations, we then provide\ntwo Dirac semimetal candidates, i.e., Na3Bi and NaTeAu, and show that under a\nZeeman field they exhibit a sizable ANC value of 0.4 A/(m*K) and 1.3 A/(m*K),\nrespectively, near the Fermi level. Our work provides a design principle with a\nprototype band structure for enhanced ANC pinning at Fermi level, shedding\nlight on the inverse design of other specific functional materials base on\nelectronic structure."
    },
    {
        "anchor": "Digital Twins in Graphene Technology: The Digital Twins concept in science has a long history that goes back to the\nbeginnings of now widely accepted modelling. The ever-expanding amount of\ndigital data accompanying modelling could not but cause a qualitative\ntransition from modelling, subordinated to the goal of reproducing a real\nobject, to an equal-right Digital Twins concept that offers an independent view\nof the real object. This chapter presents the first example of such a\nconceptual rethinking, using the example of material science of high-tech\ngraphene materials.",
        "positive": "High spin-polarization in the low Curie temperature complex itinerant\n  ferromagnet EuTi$_{1-x}$Nb$_x$O$_3$: The physical systems with ferromagnetism and \"bad\" metallicity hosting\nunusual transport properties are playgrounds of novel quantum phenomena.\nRecently EuTi$_{1-x}$Nb$_x$O$_3$ emerged as a ferromagnetic system where\nnon-trivial temperature dependent transport properties are observed due to\ncoexistence and competition of various magnetic and non-magnetic scattering\nprocesses. In the ferromagnetic state, the resistivity shows a $T^2$\ntemperature dependence possibly due to electron-magnon scattering and above the\nCurie temperature $T_c$, the dependence changes to $T^{3/2}$ behaviour\nindicating a correlation between transport and magnetic properties. In this\npaper, we show that the transport spin-polarization in EuTi$_{1-x}$Nb$_x$O$_3$,\na low Curie temperature ferromagnet, is as high ($\\sim 40\\%$) as that in some\nof the metallic ferromagnets with high Curie temperatures. In addition, owing\nto the low Curie temperature of EuTi$_{1-x}$Nb$_x$O$_3$, the temperature ($T$)\ndependence of $P_t$ could be measured systematically up to $T_c$ which revealed\na proportionate relationship with magnetization $M_s$ vs. $T$. This indicates\nthat such proportionality is far more universally valid than the ferromagnets\nwith ideal parabolic bands. Furthermore, our band structure calculations not\nonly helped understand the origin of such high spin polarization in\nEuTi$_{1-x}$Nb$_x$O$_3$ but also provided a route to estimate the Hubbard $U$\nparameter in complex metallic ferromagnets in general using experimental\ninputs."
    },
    {
        "anchor": "Coexistence of Surface Ferromagnetism and Gapless Topological State in\n  MnBi$_2$Te$_4$: Surface magnetism and its correlation with the electronic structure are\ncritical to understand the gapless topological surface state in the intrinsic\nmagnetic topological insulator MnBi$_2$Te$_4$. Here, using static and time\nresolved angle-resolved photoemission spectroscopy (ARPES), we find a\nsignificant ARPES intensity change together with a gap opening on a Rashba-like\nconduction band. Comparison with a model simulation strongly indicates that the\nsurface magnetism on cleaved MnBi$_2$Te$_4$ is the same as its bulk state. The\ncoexistence of surface ferromagnetism and a gapless TSS uncovers the novel\ncomplexity of MnBi$_2$Te$_4$ that may be responsible for the low quantum\nanomalous Hall temperature of exfoliated MnBi$_2$Te$_4$.",
        "positive": "Magnetization reversal in mixed ferrite-chromite perovskites with non\n  magnetic cation on the A-site: In this work, we have performed Monte Carlo simulations in a classical model\nfor RFe$_{1-x}$Cr$_x$O$_3$ with R=Y and Lu, comparing the numerical simulations\nwith experiments and mean field calculations. In the analyzed compounds, the\nantisymmetric exchange or Dzyaloshinskii-Moriya (DM) interaction induced a weak\nferromagnetism due to a canting of the antiferromagnetically ordered spins.\nThis model is able to reproduce the magnetization reversal (MR) observed\nexperimentally in a field cooling process for intermediate $x$ values and the\ndependence with $x$ of the critical temperatures. We also analyzed the\nconditions for the existence of MR in terms of the strength of DM interactions\nbetween Fe$^{3+}$ and Cr$^{3+}$ ions with the x values variations."
    },
    {
        "anchor": "Spin gapless semiconductors: Spin gapless semiconductors (SGSs) are a new class of zero gap materials\nwhich have a fully spin polarised electrons and holes. They bridge zero gap\nmaterials and half-metals. The band structures of the SGSs can have two types\nof energy dispersions: Dirac linear dispersion and parabolic dispersion. The\nDirac type SGSs exhibit fully spin polarized Dirac cones, and offer a platform\nfor massless and fully spin polarized spintronics as well as dissipationless\nedge state via quantum anomalous Hall effect. Due to its fascinating spin and\ncharge states, they hold great potential application in spintronics. There have\nbeen tremendous efforts worldwide on searching for suitable candidates of SGSs.\nIn particularly, there is an increasing interest in searching for Dirac type\nSGSs. In the past decade, a large number of Dirac or parabolic type SGSs have\nbeen predicted by density functional theory and some of parabolic SGSs have\nbeen experimentally demonstrated. The SGSs hold great potential for high speed\nand low-energy consumption spintronics, electronics and optoelectronics. Here,\nwe review both Dirac and parabolic types of SGSs in different materials systems\nand outline the concepts of SGSs, novel spin and charge states, and potential\napplications of SGSs in next generation spintronic devices.",
        "positive": "Magnetic structure and dynamics of a strongly one-dimensional\n  cobalt$^{II}$ metal-organic framework: We investigate the magnetism of the\nCo$^{II}_4$(OH)$_2$(C$_1$$_0$H$_1$$_6$O$_4$)$_3$ metal-organic framework which\ndisplays complex inorganic chains separated from each other by distances of 1\nto 2 nm, and which orders at ~5.4 K. The zero-field magnetic structure is\ndetermined using neutron powder diffraction: it is mainly antiferromagnetic but\nposseses a ferromagnetic component along the $\\textbf{c}$-axis. This magnetic\nstructure persists in presence of a magnetic field. Ac susceptibility\nmeasurements confirm the existence of a single thermally activated regime over\n7 decades in frequency ($E/k_B\\approx64 K$) whereas time-dependent relaxation\nof the magnetization after saturation in an external field leads to a two times\nsmaller energy barrier. These experiments probe the slow dynamics of domain\nwalls within the chains: we propose that the ac measurements are sensitive to\nthe motion of existing domain walls within the chains, while the magnetization\nmeasurements are governed by the creation of domain walls."
    },
    {
        "anchor": "A new and simple model for magneto-optics uncovers an unexpected spin\n  switching: In magneto-optics the spin angular momentum $S_z$ of a sample is indirectly\nprobed by the rotation angle and ellipticity, which are mainly determined by\nthe off-diagonal susceptibility $\\chi^{(1)}_{xy}$. A direct and analytic\nrelation between $S_z$ and $\\chi^{(1)}_{xy}$ is necessary and of paramount\nimportance to the success of magneto-optics, but is often difficult to acquire\nsince quantum mechanically the relation is hidden in the sum-over-states. Here\nwe propose a new and simple model to establish such a much needed relation. Our\nmodel is based on the Hookean model, but includes spin-orbit coupling. Under cw\nexcitation, we show that $\\chi^{(1)}_{xy}(\\omega)$ is indeed directly\nproportional to $S_z$ for a fixed photon frequency $\\omega$. Such an elegant\nrelation is encouraging, and we wonder whether our model can describe spin\ndynamics as well. By allowing the spin to change dynamically, to our surprise,\nour model predicts that an ultrafast laser pulse can induce a spin precession;\nwith appropriate parameters, the laser can even reverse spin from one direction\nto another. This works for both the circularly and linearly polarized light.\nThe spin reversal window is narrow. These unexpected results closely resemble\nall-optical helicity-dependent magnetic switching found in much more\ncomplicated ferrimagnetic rare earth compounds. Therefore, we believe that our\nspin-orbit coupled model may find some important applications in spin switching\nprocesses, a hot topic in femtomagnetism.",
        "positive": "Site-selective magnetic moment collapse in compressed Fe5O6: Iron oxide is one of the most important components in Earth's mantle. Recent\ndiscovery of the stable presence of Fe5O6 at Earth's mantle environment\nstimulates significant interests in the understanding of this new category of\niron oxides. In this paper, we report the electronic structure and magnetic\nproperties of Fe5O6 calculated by the density functional theory plus dynamic\nmean field theory (DFT+DMFT) approach. Our calculations indicate that Fe5O6 is\na conductor at the ambient pressure with dominant Fe-3d density of states at\nthe Fermi level. The magnetic moments of iron atoms at three non-equivalent\ncrystallographic sites in Fe5O6 collapse at significantly different rate under\npressure. Such site-selective collapse of magnetic moments originates from the\nshifting of energy levels and the consequent charge transfer among the Fe-3d\norbits when Fe5O6 is being compressed. Our simulations suggest that there could\nbe high conductivity and volume contraction in Fe5O6 at high pressure, which\nmay induce anomalous features in seismic velocity, energy exchange, and mass\ndistribution at the deep interior of Earth."
    },
    {
        "anchor": "A Koopmans-compliant screened exchange potential with correct asymptotic\n  behavior for semiconductors: The performance of density functional theory depends largely on the\napproximation applied for the exchange functional. We propose here a novel\nscreened exchange potential for semiconductors, with parameters based on the\nphysical properties of the underlying microscopic screening and obeying the\nrequirements for proper asymptotic behavior. We demonstrate that this\nfunctional is Koopmans-compliant and reproduces a wide range of band gaps. We\nalso show, that the only tunable parameter of the functional can be kept\nconstant upon changing the cation or the anion isovalently, making the approach\nsuitable for treating alloys.",
        "positive": "Electronic structure of buried LaNiO3 layers in (111)-oriented\n  LaNiO3/LaMnO3 superlattices probed by soft x-ray ARPES: Taking advantage of the large electron escape depth of soft x-ray angle\nresolved photoemission spectroscopy we report electronic structure measurements\nof (111)-oriented [LaNiO3/LaMnO3] superlattices and LaNiO3 epitaxial films. For\nthin films we observe a 3D Fermi surface with an electron pocket at the\nBrillouin zone center and hole pockets at the zone vertices. Superlattices with\nthick nickelate layers present a similar electronic structure. However, as the\nthickness of the LaNiO3 is reduced the superlattices become insulating. These\nheterostructures do not show a marked redistribution of spectral weight in\nmomentum space but exhibit a pseudogap of 50 meV."
    },
    {
        "anchor": "Computational Analysis of Composition-Structure-Property-Relationships\n  in NZP-type Materials for Li-Ion Batteries: Compounds crystallizing in the structure of NaZr$_2$(PO$_4$)$_3$ (NZP) are\nconsidered as promising materials for solid state electrolytes in Li-ion\nbatteries. Using density functional theory (DFT), a systematic computational\nscreening of 18 NZP compounds, namely LiX$_2$(LO$_4$)$_3$ with X = Ti, V, Fe,\nZr, Nb, Ru, Hf, Ta, Os, and L = P, Mn is performed with respect to their\nactivation energies for vacancy-mediated Li migration. It is shown how the\ndifferent ionic radii of the cationic substitutions influence structural\ncharacteristics such as the octahedron volumes around Li ions on the initial\nand transition state sites, which affect the activation energies\n(''composition-structure-property'' relationships). The prevalent assumption\nthat structural bottlenecks formed by triangularly arranged oxygen atoms at a\ncertain location along the migration path determine the energy barriers for Li\nmigration is not supported by the DFT results. Instead, the ionic neighborhood\nof the migrating ion in the initial and in the transition state needs to be\ntaken into account to relate the structure to the activation energies. This\nconclusion applies to Na containing NZP compounds as well.",
        "positive": "Role of crystal lattice structure in predicting fracture toughness: We examine the atomistic scale dependence of material's resistance-to-failure\nby numerical simulations and analytical analysis in electrical analogs of\nbrittle crystals. We show that fracture toughness depends on the lattice\ngeometry in a way incompatible with Griffith's relationship between fracture\nand free surface energy. Its value finds its origin in the matching between the\ncontinuum displacement field at the engineering scale, and the discrete nature\nof solids at the atomic scale. The generic asymptotic form taken by this field\nnear the crack tip provides a solution for this matching, and subsequently a\nway to predict toughness from the atomistic parameters with application to\ngraphene."
    },
    {
        "anchor": "Isotope Frequency Shifts of BH Local Pair Modes in Crystalline Silicon: Isotope frequency shifts of local pair modes due to B$^{10}$ (B$^{11}$)\nsubstitutional and H (D) interstitial in crystalline silicon are calculated as\na many body problem with a simple model and found to be in agreement with\nexperiment. A comparison of the obtained results is made with other theoretical\ncalculations.",
        "positive": "Full-Potential LMTO: Total Energy and Force Calculations: The essential features of a full potential electronic structure method using\nLinear Muffin-Tin Orbitals (LMTOs) are presented. The electron density and\npotential in the this method are represented with no inherent geometrical\napproximation. This method allows the calculation of total energies and forces\nwith arbitrary accuracy while sacrificing much of the efficiency and physical\ncontent of approximate methods such as the LMTO-ASA method."
    },
    {
        "anchor": "Anomalously Abrupt Switching of Ferroelectric Wurtzites: Ferroelectric polarization switching is one common example of a process that\noccurs via nucleation and growth, and understanding switching kinetics is\ncrucial for applications such as ferroelectric memory. Here we describe and\ninterpret anomalous switching dynamics in the wurtzite nitride thin film\nferroelectrics Al0.7Sc0.3N and Al0.94B0.06N using a general model that can be\ndirectly applied to other abrupt transitions that proceed via nucleation and\ngrowth. When substantial growth and impingement occur while nucleation rate is\nincreasing, such as in these wurtzite ferroelectrics under high electric\nfields, abrupt polarization reversal leads to very large Avrami coefficients\n(e.g., n = 11), inspiring an extension of the KAI (Kolmogorov-Avrami-Ishibashi)\nmodel. We apply this extended model to two related but distinct scenarios that\ncrossover between (typical) behavior described by sequential nucleation and\ngrowth and a more abrupt transition arising from significant growth prior to\npeak nucleation rate. This work therefore provides more complete description of\ngeneral nucleation and growth kinetics applicable to any system while\nspecifically addressing both the anomalously abrupt polarization reversal\nbehavior in new wurtzite ferroelectrics.",
        "positive": "Adjacent Fe-Vacancy Interactions as the Origin of Room Temperature\n  Ferromagnetism in (In$_{1-x}$Fe$_x$)$_2$O$_3$: Dilute magnetic semiconductors (DMSs) show great promise for applications in\nspin-based electronics, but in most cases continue to elude explanations of\ntheir magnetic behavior. Here, we combine quantitative x-ray spectroscopy and\nAnderson impurity model calculations to study ferromagnetic Fe-substituted\nIn$_2$O$_3$ films, and we identify a subset of Fe atoms adjacent to oxygen\nvacancies in the crystal lattice which are responsible for the observed room\ntemperature ferromagnetism. Using resonant inelastic x-ray scattering, we map\nout the near gap electronic structure and provide further support for this\nconclusion. Serving as a concrete verification of recent theoretical results\nand indirect experimental evidence, these results solidify the role of\nimpurity-vacancy coupling in oxide-based DMSs."
    },
    {
        "anchor": "Exploiting the close-to-Dirac point shift of Fermi level in\n  Sb2Te3/Bi2Te3 topological insulator heterostructure for spin-charge\n  conversion: Properly tuning the Fermi level position in topological insulators is of\nvital importance to tailor their spin-polarized electronic transport and to\nimprove the efficiency of any functional device based on them. Here we report\nthe full in situ Metal Organic Chemical Vapor Deposition (MOCVD) and study of a\nhighly crystalline Bi2Te3/Sb2Te3 topological insulator heterostructure on top\nof large area (4'') Si(111) substrates. The bottom Sb2Te3 layer serves as an\nideal seed layer for the growth of highly crystalline Bi2Te3 on top, also\ninducing a remarkable shift of the Fermi level to place it very close to the\nDirac point, as visualized by angle-resolved photoemission spectroscopy. In\norder to exploit such ideal topologically-protected surface states, we\nfabricate the simple spin-charge converter Si(111)/Sb2Te3/Bi2Te3/Au/Co/Au and\nspin-charge conversion (SCC) is probed by spin pumping ferromagnetic resonance.\nA large SCC is measured at room temperature, which is interpreted within the\ninverse Edelstein effect (IEE), thus resulting in a conversion efficiency\nlambda_IEE of 0.44 nm. Our results demonstrate the successful tuning of the\nsurface Fermi level of Bi2Te3 when grown on top of Sb2Te3 with a full in situ\nMOCVD process, which is highly interesting in view of its future technology\ntransfer.",
        "positive": "Quantitatively Designing Porous Copper Current Collectors for Lithium\n  Metal Anode: Lithium metal has been an attractive candidate as a next generation anode\nmaterial. Despite its popularity, stability issues of lithium in the liquid\nelectrolyte and the formation of lithium whiskers have kept it from practical\nuse. Three-dimensional (3D) current collectors have been proposed as an\neffective method to mitigate whiskers growth. Although extensive research\nefforts have been done, the effects of three key parameters of the 3D current\ncollectors, namely the surface area, the tortuosity factor, and the surface\nchemistry, on the performance of lithium metal batteries remain elusive.\nHerein, we quantitatively studied the role of these three parameters by\nsynthesizing four types of porous copper networks with different sizes of\nwell-structured micro-channels. X-ray microscale computed tomography (micro-CT)\nallowed us to assess the surface area, the pore size and the tortuosity factor\nof the porous copper materials. A metallic Zn coating was also applied to study\nthe influence of surface chemistry on the performance of the 3D current\ncollectors. The effects of these parameters on the performance were studied in\ndetail through Scanning Electron Microscopy (SEM) and Titration Gas\nChromatography (TGC). Stochastic simulations further allowed us to interpret\nthe role of the tortuosity factor in lithiation. By understanding these\neffects, the optimal range of the key parameters is found for the porous copper\nanodes and their performance is predicted. Using these parameters to inform the\ndesign of porous copper anodes for Li deposition, Coulombic efficiencies (CE)\nof up to 99.56% are achieved, thus paving the way for the design of effective\n3D current collector systems."
    },
    {
        "anchor": "Ab-initio structural, elastic, and vibrational properties of carbon\n  nanotubes: A study based on ab initio calculations is presented on the estructural,\nelastic, and vibrational properties of single-wall carbon nanotubes with\ndifferent radii and chiralities. We use SIESTA, an implementation of\npseudopotential-density-functional theory which allows calculations on systems\nwith a large number of atoms per cell. Different quantities like bond\ndistances, Young moduli, Poisson ratio and the frequencies of different phonon\nbranches are monitored versus tube radius. The validity of expectations based\non graphite is explored down to small radii, where some deviations appear\nrelated to the curvature effects. For the phonon spectra, the results are\ncompared with the predictions of the simple zone-folding approximation. Except\nfor the known defficiencies of this approximation in the low-frequency\nvibrational regions, it offers quite accurate results, even for relatively\nsmall radii.",
        "positive": "GaN:Gd: A superdilute ferromagnetic semiconductor with a Curie\n  temperature above 300 K: We investigate the magnetic and magneto-optic properties of epitaxial GaN:Gd\nlayers as a function of the external magnetic field and temperature. An\nunprecedented magnetic moment is observed in this diluted magnetic\nsemiconductor. The average value of the moment per Gd atom is found to be as\nhigh as 4000 \\mub as compared to its atomic moment of 8 \\mub. The long-range\nspin-polarization of the GaN matrix by Gd is also reflected in the circular\npolarization of magneto-photoluminescence measurements. Moreover, the materials\nsystem is found to be ferromagnetic above room temperature in the entire\nconcentration range under investigation (7$\\times10^{15}$ to 2$\\times10^{19}$\ncm$^{-3}$). We propose a phenomenological model to understand the macroscopic\nmagnetic behavior of the system. Our study reveals a close connection between\nthe observed ferromagnetism and the colossal magnetic moment of Gd."
    },
    {
        "anchor": "Anisotropic two-dimensional electron gas at SrTiO3(110) protected by its\n  native overlayer: Two dimensional electron gases (2DEGs) at a oxide heterostructures are\nattracting considerable attention, as these might substitute conventional\nsemiconductors for novel electronic devices [1]. Here we present a minimal\nset-up for such a 2DEG -the SrTiO3(110)-(4 x 1) surface, natively terminated\nwith one monolayer of chemically-inert titania. Oxygen vacancies induced by\nsynchrotron radiation migrate under- neath this overlayer, this leads to a\nconfining potential and electron doping such that a 2DEG develops. Our angular\nresolved photoemission spectroscopy (ARPES) and theoretical results show that\nconfinement along (110) is strikingly different from a (001) crystal\norientation. In particular the quantized subbands show a surprising\n\"semi-heavy\" band, in contrast to the analogue in the bulk, and a high\nelectronic anisotropy. This anisotropy and even the effective mass of the (110)\n2DEG is tunable by doping, offering a high flexibility to engineer the\nproperties of this system.",
        "positive": "Noise-dependent bias in quantitative STEM-EMCD experiments revealed by\n  bootstrapping: Electron magnetic circular dichroism (EMCD) is a powerful technique for\nestimating element-specific magnetic moments of materials on nanoscale with the\npotential to reach atomic resolution in transmission electron microscopes.\nHowever, the fundamentally weak EMCD signal strength complicates quantification\nof magnetic moments, as this requires very high precision, especially in the\ndenominator of the sum rules. Here, we employ a statistical resampling\ntechnique known as bootstrapping to an experimental EMCD dataset to produce an\nempirical estimate of the noise dependent error distribution resulting from\napplication of EMCD sum rules to bcc iron in a 3 beam orientation. We observe\nclear experimental evidence that noisy EMCD signals preferentially bias the\nestimation of magnetic moments, further supporting this with error\ndistributions produced by Monte-Carlo simulations. Finally, we propose\nguidelines for the recognition and minimization of this bias in the estimation\nof magnetic moments."
    },
    {
        "anchor": "Topological Metal of NaBi with Ultralow Lattice Thermal Conductivity and\n  Electron-phonon Superconductivity: By means of first-principles and \\emph{ab initio} tight-binding calculations,\nwe found that the compound of NaBi is a three-dimensional non-trivial\ntopological metal. Its topological feature can be confirmed by the presence of\nband inversion, the derived effective Z$_2$ invariant and the non-trivial\nsurface states with the presence of Dirac cones. Interestingly, our\ncalculations further demonstrated that NaBi exhibits the uniquely combined\nproperties between the electron-phonon coupling superconductivity in nice\nagreement with recent experimental measurements and the obviously anisotropic\nbut extremely low thermal conductivity. The spin-orbit coupling effects greatly\naffect those properties. NaBi may provide a rich platform to study the\nrelationship among metal, topology, superconductivity and thermal conductivity.",
        "positive": "Probing the dynamics of quasicrystal growth using synchrotron live\n  imaging: The dynamics of quasicrystal growth remains an unsolved problem in condensed\nmatter. By means of synchrotron live imaging, facetted growth proceeding by the\ntangential motion of ledges at the solid-melt interface is clearly evidenced\nall along the solidification of icosahedral AlPdMn quasicrystals. The effect of\ninterface kinetics is significant so that nucleation and free growth of new\nfacetted grains occur in the melt when the solidification rate is increased.\nThe evolution of these grains is explained in details, which reveals the\ncrucial role of aluminum rejection, both in the poisoning of grain growth and\ndriving fluid flow."
    },
    {
        "anchor": "Photoluminescence of single colour defects in 50 nm diamond nanocrystals: We used optical confocal microscopy to study optical properties of diamond 50\nnm nanocrystals first irradiated with an electron beam, then dispersed as a\ncolloidal solution and finally deposited on a silica slide. At room\ntemperature, under CW laser excitation at a wavelength of 514.5 nm we observed\nperfectly photostable single Nitrogen-Vacancy (NV) colour defects embedded in\nthe nanocrystals. From the zero-phonon line around 575 nm in the spectrum of\nemitted light, we infer a neutral NV0 type of defect. Such nanoparticle with\nintrinsic fluorescence are highly promising for applications in biology where\nlong-term emitting fluorescent bio-compatible nanoprobes are still missing.",
        "positive": "Strain Anisotropy Driven Spontaneous Formation of Nanoscrolls from\n  Two-Dimensional Janus Layers: Two-dimensional Janus transition metal dichalcogenides (TMDs) have attracted\nattention due to their emergent properties arising from broken mirror symmetry\nand self-driven polarisation fields. While it has been proposed that their vdW\nsuperlattices hold the key to achieving superior properties in piezoelectricity\nand photovoltiacs, available synthesis has ultimately limited their\nrealisation. Here, we report the first packed vdW nanoscrolls made from Janus\nTMDs through a simple one-drop solution technique. Our results, including\nab-initio simulations, show that the Bohr radius difference between the top\nsulphur and the bottom selenium atoms within Janus M_Se^S (M=Mo, W) results in\na permanent compressive surface strain that acts as a nanoscroll formation\ncatalyst after small liquid interaction. Unlike classical 2D layers, the\nsurface strain in Janus TMDs can be engineered from compressive to tensile by\nplacing larger Bohr radius atoms on top (M_S^Se) to yield inverted C scrolls.\nDetailed microscopy studies offer the first insights into their morphology and\nreadily formed Moir\\'e lattices. In contrast, spectroscopy and FETs studies\nestablish their excitonic and device properties and highlight significant\ndifferences compared to 2D flat Janus TMDs. These results introduce the first\npolar Janus TMD nanoscrolls and introduce inherent strain-driven scrolling\ndynamics as a catalyst to create superlattices."
    },
    {
        "anchor": "Theoretical guidelines to create and tune electric skyrmions: Magnetic skyrmions are mesmerizing spin textures with peculiar topological\nand dynamical properties, typically the product of competing interactions in\nferromagnets, and with great technological potential [1-5]. Researchers have\nlong wondered whether analogous electric skyrmions might exist in\nferroelectrics, maybe featuring novel behaviors and possibilities for electric\nand mechanical control. The results thus far are modest, though: an electric\nequivalent of the most typical magnetic skyrmion (which would rely on a\ncounterpart of the Dzyaloshinskii-Moriya interaction) seems all but impossible;\nfurther, the exotic ferroelectric orders observed or predicted to date [6-8]\nrely on very specific nano-structures (composites, superlattices), which limits\nthe generality and properties (e.g., mobility) of the possible associated\nskyrmions. Here we propose an original approach to write electric skyrmions in\nsimple ferroelectric lattices in a customary manner. Our second-principles\nsimulations [9] of columnar ferroelectric nano-domains, in prototype compound\nPbTiO3 , show that it is possible to harness the Bloch-type internal structure\nof the domain wall [10] and hence create a genuine skyrmion. We check that the\nobject thus obtained displays the usual skyrmion-defining features; further, it\nalso presents unusual ones, including a symmetry-breaking skyrmion-skyrmion\ntransition driven by strain, various types of topological transformations\ninduced by external fields and temperature, and potentially very small sizes.\nOur results suggest countless possibilities for creating and manipulating\nelectric textures with non-trivial topologies, using standard experimental\ntools and materials, effectively inaugurating the field of electric skyrmions.",
        "positive": "Untangling the structural, magnetic dipole, and charge multipolar orders\n  in Ba$_2$MgReO$_6$: We present a density functional theory study of the low-temperature\nstructural, magnetic, and proposed charge-quadrupolar ordering in the double\nperovskite, Ba$_2$MgReO$_6$. Ba$_2$MgReO$_6$ is a spin-orbit-driven Mott\ninsulator with a symmetry-lowering structural phase transition at 33\\,K and a\ncanted antiferromagnetic ordering of $5d^1$ Re magnetic moments at 18\\,K. Our\ncalculations confirm the existence of the proposed charge quadrupolar order and\ndiscover an additional, previously hidden, ordered charge quadrupolar\ncomponent. By separately isolating the structural distortions and the\norientations of the magnetic dipoles, we determine the relationship between the\ncharge quadrupolar, structural and magnetic orders, finding that either a local\nstructural distortion or a specific magnetic dipole orientation is required to\nlower the symmetry and enable the existence of charge quadrupoles. Our work\nestablishes the crystal structure -- magnetic dipole -- charge multipole\nrelationship in Ba$_2$MgReO$_6$ and related 5$d^1$ double perovskites, and\nillustrates a method for separating and analyzing the contributions and\ninteractions of structural, magnetic, and charge orders beyond the usual dipole\nlevel."
    },
    {
        "anchor": "Electron-phonon coupling in semimetals in a high magnetic field: We consider the effect of electron-phonon coupling in semimetals in high\nmagnetic fields, with regard to elastic modes that can lead to a redistribution\nof carriers between pockets. We show that in a clean three dimensional system,\nat each Landau level crossing, this leads to a discontinuity in the\nmagnetostriction, and a divergent contribution to the elastic modulus. We\nestimate the magnitude of this effect in the group V semimetal Bismuth.",
        "positive": "Epitaxial stabilization and phase instability of VO2 polymorphs: The VO2 polymorphs, i.e., VO2(A), VO2(B), VO2(M1) and VO2(R), have a wide\nspectrum of functionalities useful for many potential applications in\ninformation and energy technologies. However, synthesis of phase pure\nmaterials, especially in thin film forms, has been a challenging task due to\nthe fact that the VO2 polymorphs are closely related to each other in a\nthermodynamic framework. Here, we report epitaxial stabilization of the VO2\npolymorphs to synthesize high quality single crystalline thin films and study\nthe phase stability of those metastable materials. We selectively deposit all\nthe phases on various perovskite substrates with different crystallographic\norientations. By investigating the phase instability, phonon modes and\ntransport behaviours, not only do we find distinctively contrasting physical\nproperties of the VO2 polymorphs, but that the polymorphs could be on the verge\nof phase transitions when heated as low as ~400 oC. Our successful epitaxy of\nboth VO2(A) and VO2(B) phases, which are rarely studied due to the lack of\nphase pure materials, will open the door to the fundamental studies of VO2\npolymorphs for potential applications in advanced electronic and energy\ndevices."
    },
    {
        "anchor": "The Role of Long-lived Excitons in the Dynamics of Strongly Coupled\n  Molecular Polaritons: The concept of modifying molecular dynamics in strongly coupled\nexciton-polariton systems is an emerging topic in photonics due to its\npotential to produce customized chemical systems with tailored photophysical\nproperties. However, before such systems can be realized, it is essential to\naddress the open questions concerning the nature and strength of electronic\ninteractions between exciton-polaritons and localized excited states in\nchemical system as well as the proper way to measure such interactions. Here,\nwe use transient optical spectroscopy to investigate dynamical interactions\nbetween exciton-polaritons, singlet excitons, and triplet excitons in a\nmolecular singlet fission system that is strongly coupled to an optical\nmicrocavity. We identify some of the major limitations to modify molecular\ndynamics in the strong coupling regime. Simultaneous excitation of cavity\npolaritons and 'reservoir' states, defined as dark polaritons and dark excitons\n(e.g. triplets) from coupled molecules and excitons from uncoupled molecules,\nalways occurs. In addition, slow conversion from reservoir states to cavity\npolaritons results in minimal changes to the overall population dynamics.\nFurthermore, we demonstrate how in addition to the usual population dynamics,\ntransient optical measurements on microcavities reveal information pertaining\nto modification of the exciton-polariton transition energies due to changes in\nthe population of molecular excited states and the exciton-photon coupling\nconditions. As a consequence of weak interactions between reservoir states and\ncavity polaritons, judicious design considerations are required to achieve\nmodified chemical dynamics, necessitating the use of molecular systems with\nlong excited-state lifetimes or strong coupling approaches that require a small\nnumber of molecules.",
        "positive": "Remarks on \"Piezonuclear neutrons from fracturing of inert solids\": In two series of measurements, Cardone, Carpinteri et al. report an excess of\nneutrons over the background flux corresponding to the catastrophic fracture of\na granite block subject to compression. Here we show that these measurements\ncontain large inconsistencies with respect to the stated experimental\nprocedure, including fractional neutron counts and strongly non Poissonian\nstatistics"
    },
    {
        "anchor": "Clar's Theory, STM Images, and Geometry of Graphene Nanoribbons: We show that Clar's theory of the aromatic sextet is a simple and powerful\ntool to predict the stability, the \\pi-electron distribution, the geometry, the\nelectronic/magnetic structure of graphene nanoribbons with different hydrogen\nedge terminations. We use density functional theory to obtain the equilibrium\natomic positions, simulated scanning tunneling microscopy (STM) images, edge\nenergies, band gaps, and edge-induced strains of graphene ribbons that we\nanalyze in terms of Clar formulas. Based on their Clar representation, we\npropose a classification scheme for graphene ribbons that groups configurations\nwith similar bond length alternations, STM patterns, and Raman spectra. Our\nsimulations show how STM images and Raman spectra can be used to identify the\ntype of edge termination.",
        "positive": "Molecular Dynamics Simulation of Cross-linked Graphene-Epoxy\n  Nanocomposites: This paper focuses on molecular dynamics (MD) modeling of graphene reinforced\ncross-linked epoxy (Gr-Ep) nanocomposite. The goal is to study the influence of\ngeometry, and concentration of reinforcing nanographene sheet (NGS) on\ninterfacial properties and elastic constants such as bulk Young's modulus, and\nshear modulus of Gr-Ep nanocomposites. The most typical cross-linked\nconfiguration was obtained in order to use in further simulations. The\nmechanical properties of this cross-linked structure were determined using MD\nsimulations and the results were verified with those available in literatures.\nGraphene with different aspect ratios and concentrations (1%, 3% and 5%) were\nconsidered in order to construct amorphous unit cells of Gr-Ep nanocomposites.\nThe Gr-Ep nanocomposites system undergoes NVT (constant number of atoms, volume\nand temperature) and NPT (constant number of atoms, pressure and temperature)\nensemble with applied uniform strain field during MD simulation to obtain bulk\nYoung's modulus and shear modulus. The stress-strain response was also\nevaluated for both amorphous and crystalline unit cells of Gr-Ep system under\nuni-axial deformation. The cohesive and pullout force vs. displacement response\nwere determined for graphenes with different size. Hence as primary goal of\nthis work, a parametric study using MD simulation was conducted for\ncharacterizing interfacial properties and elastic constants with different NGS\naspect rations and volume fractions. The MD simulation results show reasonable\nagreement with available published data in the literature."
    },
    {
        "anchor": "A scale-bridging modeling approach for anisotropic organic molecules at\n  patterned semiconductor surfaces: Hybrid systems consisting of organic molecules at inorganic semiconductor\nsurfaces are gaining increasing importance as thin film devices for\noptoelectronics. The efficiency of such devices strongly depends on the\ncollective behavior of the adsorbed molecules. In the present paper we propose\na novel, coarse-grained model addressing the condensed phases of a\nrepresentative hybrid system, that is, para-sexiphenyl (6P) at zinc-oxide\n(ZnO). Within our model, intermolecular interactions are repre- sented via a\nGay-Berne potential (describing steric and van-der-Waals interactions) combined\nwith the electrostatic potential between two linear quadrupoles. Similarly, the\nmolecule-substrate interactions include a coupling between a linear molecular\nquadrupole to the electric field generated by the line charges characterizing\nZnO(10-10). To validate our approach, we perform equilibrium Monte Carlo\nsimulations, where the lateral positions are fixed to a 2D lattice, while the\nrotational degrees of freedom are continuous. We use these simulations to\ninvestigate orientational ordering in the condensed state. We reproduce various\nexperimentally observed features such as the alignment of individual molecules\nwith the line charges on the surface, the formation of a standing uniaxial\nphase with a herringbone structure, as well as the formation of a lying nematic\nphase.",
        "positive": "Prediction of a novel monoclinic carbon allotrope: A novel allotrope of carbon with $P2/m$ symmetry was identified during an\n\\emph{ab-initio} minima-hopping structural search which we call $M10$-carbon.\nThis structure is predicted to be more stable than graphite at pressures above\n14.4 GPa and consists purely of $sp^3$ bonds. It has a high bulk modulus and is\nalmost as hard as diamond. A comparison of the simulated X-ray diffraction\npattern shows a good agreement with experimental results from cold compressed\ngraphite."
    },
    {
        "anchor": "Bulk Photovoltaic Effect in Two-Dimensional Distorted MoTe2: In future solar cell technologies, the thermodynamic Shockley-Queisser limit\nfor solar-to-current conversion in traditional p-n junctions could potentially\nbe overcome with a bulk photovoltaic effect by creating an inversion broken\nsymmetry in piezoelectric or ferroelectric materials. Here, we unveiled\nmechanical distortion-induced bulk photovoltaic behavior in a two-dimensional\nmaterial (2D), MoTe2, caused by phase transition and broken inversion symmetry\nin MoTe2. The phase transition from single-crystalline semiconducting 2H-MoTe2\nto semi-metallic 1T-MoTe2 was confirmed using X-ray photoelectron spectroscopy\n(XPS). We used a micrometer-scale system to measure the absorption of energy,\nwhich reduced from 800 meV to 63 meV when phase transformation from hexagonal\nto distorted octahedral and revealed a smaller bandgap semi-metallic behavior.\nExperimentally, a large bulk photovoltaic response is anticipated with the\nmaximum photovoltage VOC = 16 mV and a positive signal of the ISC = 60 uA (400\nnm, 90.4 Wcm-2) in the absence of an external electric field. The maximum\nvalues of both R and EQE were found to be 98 mAW-1 and 30 %, respectively. Our\nfindings unveil distinctive features of the photocurrent responses caused by\nin-plane polarity and its potential from a wide pool of established TMD-based\nnanomaterials, and a novel approach to reach high efficiency in converting\nphotons-to-electricity for power harvesting optoelectronics devices.",
        "positive": "Biomimetic method for metallic nanostructured mesoscopic models\n  fabrication: Various metallic structures of complex shape, resembling natural objects such\nas plants, mushrooms, and seashells, were produced when growing nanowires by\nmeans of pulsed current electroplating in porous membranes. These structures\noccur as the result of nanowires self-assembling (biomimetics) if the\nelectroplating is continued after the nanowires reach the membrane surface. By\nvarying the membrane geometry and the pulsed current parameters, and\nalternating electroplating from two baths with different electrolytes, various\nmodels were fabricated, including a hollow container with wall thickness of\n10-30 nm. The possibility of shape regulation for models was demonstrated: in\ncertain conditions, mushroom- and shell-like convex-concave models of the same\nkind were obtained. The hierarchical structure of models at the nano-, micro-\nand mesoscopic levels is shown through fragmentation and chemical etching."
    },
    {
        "anchor": "Exciton Bimolecular Annihilation Dynamics in Push-Pull Semiconductor\n  Polymers: Exciton-exciton annihilation is a ubiquitous nonlinear dynamical phenomenon\nin materials hosting Frenkel excitons, that has been employed to probe exciton\ndiffusion processes in conjugated polymeric materials. In this work, we\ninvestigate the nonlinear exciton dynamics of an electron push-pull conjugated\npolymer by fluence-dependent transient absorption and excitation-correlation\nphotoluminescence spectroscopy, where we can quantitatively show the latter\ntechnique to be a more selective probe of the nonlinear dynamics. Simulations\nbased on an exciton annihilation model that implements a simple (\\textit{i.e.}\\\ntime-independent) bimolecular rate constant decreasing trend for the extracted\nannihilation rates with excitation fluence. However, further investigation of\nthe fluence-dependent transients suggests that the exciton-exciton annihilation\nbimolecular rate parameters are not constant in time, displaying a $t^{-1/2}$\ntime dependence, which we rationalize as reflective of anisotropic exciton\ndiffusion. At ambient temperature, we estimate the exciton diffusion length to\nbe $9 \\pm 2$\\,nm. In addition, exciton annihilation gives rise to a long-lived\nspecies that recombines on a nanosecond timescale. Our conclusions shed broad\nlight onto nonlinear exciton dynamics in push-pull conjugated polymers.",
        "positive": "The effect of anomalous adsorption of H2O and CO2 by pre-hydrated\n  YBa_2Cu_3O_{6.53}: The results of a comprehensive study on the YBa_2Cu_3O_{6.53} oxide subjected\nto \"mild\" hydration (exposure at small values of pH2O) by a special technique\nhave been reported. The material modified in this way acquires an interesting\nproperty; namely, in natural conditions it intensively absorbs large quantities\nof components (H2O and CO2) comprising the gas atmosphere. Arguments have been\nadduced that at least the water enters the crystal lattice of the\nyttrium-barium cuprate. This lattice is in the two-phase (tetragonal and\northorhombic) state: testing of the magnetic properties of the oxide has\nrevealed the presence of antiferromagnetic and diamagnetic regions in this\nmaterial."
    },
    {
        "anchor": "Towards a Mechanism of Rattler Coupling in the \u03b2-Pyrochlores\n  AOs2O6 (A = K, Rb, Cs): We have applied ab initio molecular dynamics (MD) simulations to study\nmetal-metal coupling on the alkali-metal sublattice in the {\\beta}-pyrochlore\nosmates, AOs2O6 (A = K, Rb, Cs) at 300 K. We find that the alkali-metal atoms\n(rattlers) couple to each other more strongly than they couple to the cage\natoms, and that, at 300 K, this coupling is strongest for Cs. We show that this\ncoupling controls the dominant dynamics in the rattling of these atoms. We\nprovide preliminary evidence that the rattlers couple to each other primarily\nthrough the T2g mode whereas their coupling to the cage modes occurs through\nthe T1u mode. Rattler coupling through the T2g mode provides insight into the\ntrend in spectral broadening from Cs to K. The spectral broadening is inversely\nproportional to the strength of the dynamical correlations on the alkali-metal\nsublattice which in turn depend on the atomic size of the rattler, decreasing\nfrom Cs to K. Thus, the broadest spectrum exhibited by the K is partly a\nconsequence of the small size of this rattler which permits a greater range of\nmotions involving combinations of both correlated and anti-correlated dynamics.\nWe emphasize that the identification of the somewhat distinct roles of the T1u\nand T2g modes in rattler coupling reported in this work is a significant step\ntowards a complete fundamental mechanism of rattler dynamical coupling in these\nosmates. We believe that such a mechanism will have profound implications for a\nbroad class of cage compounds, including clathrates and skutterudites.",
        "positive": "Predicting the properties of molecular materials: multiscale simulation\n  workflows meet machine learning: Machine Learning tools are nowadays widely applied extensively to the\nprediction of the properties of molecular materials, using datasets extracted\nfrom high-throughput computational models. In several cases of scientific and\ntechnological relevance, the properties of molecular materials are related to\nthe link between molecular structure and phenomena occurring across a wide set\nof spatial scales, from the nanoscale to the macroscale. Here, we describe an\napproach for predicting the properties of molecular aggregates based on\nmultiscale simulations and machine learning."
    },
    {
        "anchor": "First-principles calculation of the intersublattice exchange\n  interactions and Curie temperatures of full Heusler alloys Ni2MnX (X=Ga, In,\n  Sn, Sb): The interatomic exchange interactions and Curie temperatures in Ni-based full\nHeusler alloys Ni2MnX with X=Ga, In, Sn and Sb are studied within the framework\nof the density-functional theory. The calculation of the exchange parameters is\nbased on the frozen-magnon approach. Despite closeness of the experimental\nCurie temperatures for all four systems their magnetism appeared to differ\nstrongly. This difference involves both the Mn-Mn and Mn-Ni exchange\ninteractions. The Curie temperatures, Tc, are calculated within the mean-field\napproximation by solving a matrix equation for a multi-sublattice system. Good\nagreement with experiment for all four systems is obtained. The role of\ndifferent exchange interactions in the formation of Tc of the systems is\ndiscussed.",
        "positive": "Using metallic photonic crystals as visible light sources: In this paper we study numerically and experimentally the possibility of\nusing metallic photonic crystals (PCs) of different geometries (log-piles,\ndirect and inverse opals) as visible light sources. It is found that by tuning\ngeometrical parameters of a direct opal PC one can achieve substantial\nreduction of the emissivity in the infrared along with its increase in the\nvisible. We take into account disorder of the PC elements in their sizes and\npositions, and get quantitative agreement between the numerical and\nexperimental results. We analyze the influence of known temperature-resistant\nrefractory host materials necessary for fixing the PC elements, and find that\nPC effects become completely destroyed at high temperatures due to the host\nabsorption. Therefore, creating PC-based visible light sources requires that\nlow-absorbing refractory materials for embedding medium be found."
    },
    {
        "anchor": "Temperature-dependent EXAFS measurements of the Pb L3-edge allow\n  quantification of the anharmonicity of the lead-halide bond of\n  chlorine-substituted methylammonium (MA) lead triiodide: This article reports on studies of chlorine-substituted MAPbI3 using combined\ntemperature-dependent XRD synchrotron and Pb-L3 edge EXAFS to analyze the\nanharmonicity of the lead halide bond. The EXAFS parameters were described in\nthe orthorhombic phase by an Einstein or T2 type behavior, which was then\ncompared with the experimental EXAFS parameters of the tetragonal/cubic phase.\nIn the orthorhombic phase, it was observed that the asymmetry of the pair\ndistribution function (cumulant C3) in MAPbCl3 is much lower than in MAPbI3.\nCompared with the behavior in the orthorhombic phase, the anharmonicity changed\nafter the phase transition to the room temperature phase, with MAPbCl3 showing\nan increased anharmonicity and MAPbI3 a decrease. The differences between\nMAPbI3 and 2% chlorine substitution were small, both in the orthorhombic and\ntetragonal phases. By determining the structural parameters required to convert\nthe effective force constants k0 and k3 resulting from the EXAFS analysis into\nthe Morse potential parameters {\\alpha} and D, we could establish that our\nresults agree with other experimental findings. Moreover, by using XRD we found\nthat the [PbX6] octahedra shrink slightly in the tetragonal phase of MAPbI3 and\nMAPbI2.94Cl0.06, towards increasing temperatures. This behavior in the\ntetragonal phase is related to the dominant negative tension effects observed\nby EXAFS.",
        "positive": "Fluctuation phenomena in crystal plasticity - a continuum model: On microscopic and mesoscopic scales, plastic flow of crystals is\ncharacterized by large intrinsic fluctuations. Deformation by crystallographic\nslip occurs in a sequence of intermittent bursts ('slip avalanches') with\npower-law size distribution. In the spatial domain, these avalanches produce\ncharacteristic deformation patterns in the form of slip lines and slip bands\nwhich exhibit long-range spatial correlations. We propose a generic continuum\nmodel which accounts for randomness in the local stress-strain relationships as\nwell as for long-range internal stresses that arise from the ensuing plastic\nstrain heterogeneities. The model parameters are related to the local dynamics\nand interactions of lattice dislocations. The model explains experimental\nobservations on slip avalanches as well as the associated slip and surface\npattern morphologies."
    },
    {
        "anchor": "Multiple antiferromagnetic phases and magnetic anisotropy in exfoliated\n  CrBr$_3$ multilayers: In twisted two-dimensional (2D) magnets, the stacking dependence of the\nmagnetic exchange interaction can lead to regions of ferromagnetic and\nantiferromagnetic interlayer order, separated by non-collinear, skyrmion-like\nspin textures. Recent experimental searches for these textures have focused on\nCrI$_3$, known to exhibit either ferromagnetic or antiferromagnetic interlayer\norder, depending on layer stacking. However, the very strong uniaxial\nanisotropy of CrI$_3$ disfavors smooth non-collinear phases in twisted\nbilayers. Here, we report the experimental observation of three distinct\nmagnetic phases -- one ferromagnetic and two antiferromagnetic -- in exfoliated\nCrBr$_3$ multilayers, and reveal that the uniaxial anisotropy is significantly\nsmaller than in CrI$_3$. These results are obtained by magnetoconductance\nmeasurements on CrBr$_3$ tunnel barriers and Raman spectroscopy, in conjunction\nwith density functional theory calculations, which enable us to identify the\nstackings responsible for the different interlayer magnetic couplings. The\ndetection of all locally stable magnetic states predicted to exist in CrBr$_3$\nand the excellent agreement found between theory and experiments, provide\ncomplete information on the stacking-dependent interlayer exchange energy and\nestablish twisted bilayer CrBr$_3$ as an ideal system to deterministically\ncreate non-collinear magnetic phases.",
        "positive": "An analytical method to quantify the statistics of energy landscapes in\n  random solid solutions: Recent studies of concentrated solid solutions have highlighted the role of\nvaried solute interactions in the determination of a wide variety of mesoscale\nproperties. These solute interactions emerge as spatial fluctuations in\npotential energy, which arise from local variations in the chemical\nenvironment. Although observations of potential energy fluctuations are well\ndocumented in the literature, there remains a paucity of methods to determine\ntheir statistics. Here, we present a set of analytical equations to quantify\nthe statistics of potential energy landscapes in randomly arranged solid\nsolutions. Our approach is based on a reparameterization of the relations of\nthe embedded atom method in terms of the solute coordination environment. The\nfinal equations are general and can be applied to different crystal lattices\nand energy landscapes, provided the systems of interest can be described by\nsets of coordination relations. We leverage these statistical relations to\nstudy the cohesive energy and generalized planar fault energy landscapes of\nseveral different solid solutions. Analytical predictions are validated using\nmolecular statics simulations, which find excellent agreement in most cases.\nThe outcomes of this analysis provide new insights into phase stability and the\ninterpretation of local planar fault energies in solid solutions, which are\ntopics of ongoing discussion within the community."
    },
    {
        "anchor": "Absolute surface energy determination: Experimental determination of absolute surface energies remains a challenge.\nWe propose a simple method based on two independent measurements on 3D and 2D\nequilibrium shapes completed by the analysis of the thermal fluctuation of an\nisolated step. Using then basic equations (Wulff' theorem, Gibbs-Thomson\nequation, thermodynamics fluctuation of an isolated step) allows us to extract\nthe absolute surface free energy of a singular face. The so-proposed method can\nbe applied when (i) all orientations exists on the equilibrium shape, (ii) the\nsurface stress is isotropic. This procedure is applied to the case of Si(111)\nwhere we find a value between 0.59 Jm-2 and 0.83 Jm-2 at 1373 K.",
        "positive": "Stoichiometry Representation Learning with Polymorphic Crystal\n  Structures: Despite the recent success of machine learning (ML) in materials science, its\nsuccess heavily relies on the structural description of crystal, which is\nitself computationally demanding and occasionally unattainable. Stoichiometry\ndescriptors can be an alternative approach, which reveals the ratio between\nelements involved to form a certain compound without any structural\ninformation. However, it is not trivial to learn the representations of\nstoichiometry due to the nature of materials science called polymorphism, i.e.,\na single stoichiometry can exist in multiple structural forms due to the\nflexibility of atomic arrangements, inducing uncertainties in representation.\nTo this end, we propose PolySRL, which learns the probabilistic representation\nof stoichiometry by utilizing the readily available structural information,\nwhose uncertainty reveals the polymorphic structures of stoichiometry.\nExtensive experiments on sixteen datasets demonstrate the superiority of\nPolySRL, and analysis of uncertainties shed light on the applicability of\nPolySRL in real-world material discovery. The source code for PolySRL is\navailable at https://github.com/Namkyeong/PolySRL_AI4Science."
    },
    {
        "anchor": "Scaling laws for step bunching on vicinal surfaces: the role of the\n  dynamical and chemical effects: We study the evolution of step bunches on vicinal surfaces using a\nthermodynamically consistent step-flow model that (i) circumvents the\nquasistatic approximation that prevails in the literature by accounting for the\ndynamics of adatom diffusion on terraces and attachment-detachment at steps\n(referred to as the dynamical effect), and (ii) generalizes the expression of\nthe step chemical potential by incorporating the necessary coupling between the\ndiffusion fields on adjacent terraces (referred to as the chemical effect).\nHaving previously shown that these effects can explain the onset of step\nbunching without recourse to the inverse Ehrlich-Schwoebel (iES) barrier or\nother extraneous mechanisms, we are here interested in the evolution of step\nbunches beyond the linear-stability regime. In particular, the numerical\nresolution of the step-flow problem yields a robust power-law coarsening of the\nsurface profile, with the bunch height growing in time as $H\\sim t^{1/2}$ and\nthe minimal interstep distance as a function of the number of steps in the\nbunch cell obeying $\\ell_{min}\\sim N^{-2/3}$. Although these exponents have\npreviously been reported, this is the first time such scaling laws are obtained\nin the absence of an iES barrier or adatom electromigration. In order to\nvalidate our simulations, we take the continuum limit of the discrete step-flow\nsystem, leading to a novel nonlinear evolution equation for the surface height.\nWe investigate the existence of self-similar solutions of this equation and\nconfirm the 1/2 coarsening exponent obtained numerically for $H$. We highlight\nthe influence of the combined dynamical-chemical effect and show that it can be\ninterpreted as an effective iES barrier in the standard BCF theory. Finally, we\nuse a Pad\\'e approximant to derive an analytical expression for the velocity of\nsteadily moving step bunches and compare it to numerical simulations.",
        "positive": "Sumanene monolayer of pure carbon: a two-dimensional Kagome-analogy\n  lattice with desirable band gap, ultrahigh carrier mobility and strong\n  exciton binding energy: Design and synthesis of novel two-dimensional (2D) materials that possess\nrobust structural stability and unusual physical properties may open up\nenormous opportunities for device and engineering applications. Herein we\npropose a 2D sumanene lattice that be regarded as a derivative of the\nconventional Kagome lattice. Our tight-binding analysis demonstrates sumanene\nlattice contains two sets of Dirac cones and two sets of flat bands near the\nFermi surface, distinctively different from the Kagome lattice. Using\nfirst-principles calculations, we theoretically suggest two possible routines\nfor realization of stable 2D sumanene monolayers (named as a phase and b\nphase), and a-sumanene monolayer can be experimentally synthesized with\nchemical vapor deposition using C21H12 as a precursor. Small binding energies\non Au(111) surface signify the possibility of their peel-off after grown on the\nnoble metal substrate. Importantly, our GW plus Bethe-Salpeter equation\ncalculations demonstrate both monolayers have moderate band gaps (1.94 eV for\na) and ultrahigh carrier mobilities (3.4*104 cm2/Vs for a). In particular,\na-sumanene monolayer possesses a strong exciton binding energy of 0.73 eV,\nsuggesting potential applications in optics."
    },
    {
        "anchor": "Effects of mechanical processing and annealing on optical coherence\n  properties of Er$^{3+}$:LiNbO$_3$ powders: Optical coherence lifetimes and decoherence processes in erbium-doped lithium\nniobate (Er$^{3+}$:LiNbO$_3$) crystalline powders are investigated for\nmaterials that underwent different mechanical and thermal treatments. Several\ncomplimentary methods are used to assess the coherence lifetimes for these\nhighly scattering media. Direct intensity or heterodyne detection of two-pulse\nphoton echo techniques was employed for samples with longer coherence lifetimes\nand larger signal strengths, while time-delayed optical free induction decays\nwere found to work well for shorter coherence lifetimes and weaker signal\nstrengths. Spectral hole burning techniques were also used to characterize\nsamples with very rapid dephasing processes. The results on powders are\ncompared to the properties of a bulk crystal, with observed differences\nexplained by the random orientation of the particles in the powders combined\nwith new decoherence mechanisms introduced by the powder fabrication. Modeling\nof the coherence decay shows that paramagnetic materials such as\nEr$^{3+}$:LiNbO$_3$ that have highly anisotropic interactions with an applied\nmagnetic field can still exhibit long coherence lifetimes and relatively simple\ndecay shapes even for a powder of randomly oriented particles. We find that\ncoherence properties degrade rapidly from mechanical treatment when grinding\npowders from bulk samples, leading to the appearance of amorphous-like behavior\nand a broadening of up to three orders of magnitude for the homogeneous\nlinewidth even when low-energy grinding methods are employed. Annealing at high\ntemperatures can improve the properties in some samples, with homogeneous\nlinewidths reduced to less than 10 kHz, approaching the bulk crystal linewidth\nof 3 kHz under the same experimental conditions.",
        "positive": "Pressure Dependence of Electronic, Vibrational and Optical Properties of\n  wurtzite-Boron Nitride: Wurtzite Boron Nitride ($w$BN) is a wide band gap BN polymorph with peculiar\nmechanical properties (hardness and stiffness). After its first synthesis in\n1963 as a transformation of hexagonal BN ($h$BN) under high temperature and\npressure conditions, a lot of progress have been made in order to stabilize\nwurtzite phase at atmospheric pressure. Today the crystallization of good\nquality samples is finally possible. This fact motivates our first principles\nstudy of the electronic, vibrational and light absorption and emission\nproperties of $w$BN over a wide range of pressures. Our findings are important\nin view of the potential use of $w$BN as a dielectric for integration in\nBN-based technologies in optoelectronics and harsh environment applications."
    },
    {
        "anchor": "Anisotropic Magnetocaloric Properties of The Ludwigite Single Crystal\n  Cu2MnBO5: We present the results of a thorough study of the specific heat and\nmagnetocaloric properties of a ludwigite crystal Cu2MnBO5 over a temperature\nrange of 60 - 350 K and in magnetic fields up to 18 kOe. It is found that at\ntemperatures below the Curie temperature (92 K), capacity possesses a linear\ntemperature-dependent behavior, which is associated with the predominance of\ntwo-dimensional antiferromagnetic interactions of magnons. The temperature\nindependence of capacity is observed in the temperature range of 95 - 160 K,\nwhich can be attributed to the excitation of the Wigner glass phase. The\nmagnetocaloric effect (i.e. the adiabatic temperature change) was assessed\nthrough a direct measurement or an indirect method using the capacity data.\nOwing to its strong magnetocrystalline anisotropy, an anisotropic MCE or the\nrotating MCE is observed in Cu2MnBO5. A deep minimum in the rotating MCE near\nthe TC is observed and may be associated with the anisotropy of the\nparamagnetic susceptibility.",
        "positive": "Macroscopic magnetization in uniform magnetic fields: The finding of a new formulation of the magnetization vector of a quantum\nsystem interacting with a static uniform magnetic field\\cite{Selenu1} is\nreported. There a gauge invariant form of its divergence is shown being\nexpressed as a function of the electronic current per state coupled with the\nBerry curvature of the quantum system. A Fourier analysis of the magnetization\nvector and magnetization density is reported as an application of the presented\nformula it could be applied in the context of computational\nmodelling\\cite{Martin} of quantum matter."
    },
    {
        "anchor": "Evolution of entanglements during the response to a uniaxial deformation\n  of lamellar triblock copolymers and polymer glasses: Using coarse-grained molecular-dynamics simulations, a generic\nstyrene-(block)-butadiene-(block)-styrene (SBS) triblock copolymer under\nlamellar conformation is used in order to investigate the mutual entanglement\nevolution when a structure of alternating glassy (S)/rubbery (B) layers is\nsubmitted to an imposed deformation. By varying the amount of loop chains\nbetween each phase, i.e. noncrossing chains, it is possible to generate\ndifferent types of S/B interface definitions. A specific boundary driven\ntensile strain protocol has been developed in order to mimic \"real\" experiments\nand measure the stress-strain curve. The same protocol is also applied to a\nreference state consisting in a directed glassy homopolymers, as well as to an\nisotropic glassy polymer. The evolution of initial mutual entanglements from\nthe undeformed samples during the whole deformation process is monitored. It is\nshown for all considered systems that initial entanglements mostly participate\nto the preyield regime of the stress-strain curve and that this network is\ndebonded during the strain-hardening regime. For triblocks with a non-null\namount of crossing chains, the lower the amount is, the longer the memory\neffect of the initial entanglement network in the postyield regime is. On the\nfly distributions of entanglements, which depart from the postyield regime,\ndepict memory effects and long time correlations during the strain-hardening\nregime. For triblocks, loop chains reinforce these effects.",
        "positive": "Scalable deeper graph neural networks for high-performance materials\n  property prediction: Machine learning (ML) based materials discovery has emerged as one of the\nmost promising approaches for breakthroughs in materials science. While\nheuristic knowledge based descriptors have been combined with ML algorithms to\nachieve good performance, the complexity of the physicochemical mechanisms\nmakes it urgently needed to exploit representation learning from either\ncompositions or structures for building highly effective materials machine\nlearning models. Among these methods, the graph neural networks have shown the\nbest performance by its capability to learn high-level features from crystal\nstructures. However, all these models suffer from their inability to scale up\nthe models due to the over-smoothing issue of their message-passing GNN\narchitecture. Here we propose a novel graph attention neural network model\nDeeperGATGNN with differentiable group normalization and skip-connections,\nwhich allows to train very deep graph neural network models (e.g. 30 layers\ncompared to 3-9 layers in previous works). Through systematic benchmark studies\nover six benchmark datasets for energy and band gap predictions, we show that\nour scalable DeeperGATGNN model needs little costly hyper-parameter tuning for\ndifferent datasets and achieves the state-of-the-art prediction performances\nover five properties out of six with up to 10\\% improvement. Our work shows\nthat to deal with the high complexity of mapping the crystal materials\nstructures to their properties, large-scale very deep graph neural networks are\nneeded to achieve robust performances."
    },
    {
        "anchor": "Accelerating first-principles estimation of thermal conductivity by\n  machine-learning interatomic potentials: A MTP/ShengBTE solution: Accurate evaluation of the thermal conductivity of a material can be a\nchallenging task from both experimental and theoretical points of view. In\nparticular for the nanostructured materials, the experimental measurement of\nthermal conductivity is associated with diverse sources of uncertainty. As a\nviable alternative to experiment, the combination of density functional theory\n(DFT) simulations and the solution of Boltzmann transport equation is currently\nconsidered as the most trusted approach to examine thermal conductivity. The\nmain bottleneck of the aforementioned method is to acquire the anharmonic\ninteratomic force constants using the computationally demanding DFT\ncalculations. In this work we propose a substantially accelerated approach for\nthe evaluation of anharmonic interatomic force constants via employing\nmachine-learning interatomic potentials (MLIPs) trained over short ab-initio\nmolecular dynamics trajectories. The remarkable accuracy of the proposed\naccelerated method is confirmed by comparing the estimated thermal\nconductivities of several bulk and two-dimensional materials with those\ncomputed by the full-DFT approach. The MLIP-based method proposed in this study\ncan be employed as a standard tool, which would substantially accelerate and\nfacilitate the estimation of lattice thermal conductivity in comparison with\nthe commonly used full-DFT solution.",
        "positive": "Simultaneous control of the Dzyaloshinskii-Moriya interaction and\n  magnetic anisotropy in nanomagnetic trilayers: Magneto-optical Kerr effect (MOKE) microscopy measurements of magnetic bubble\ndomains demonstrate that Ar+ irradiation around 100 eV can tune the\nDzyaloshinskii-Moriya interaction (DMI) in Pt/Co/Pt trilayers. Varying the\nirradiation energy and dose changes the DMI sign and magnitude separately from\nthe magnetic anisotropy, allowing tuning of the DMI while holding the coercive\nfield constant. This simultaneous control emphasizes the different physical\norigins of these effects. To accurately measure the DMI, we propose and apply a\nphysical model for a poorly understood peak in domain wall velocity at zero\nin-plane field. The ability to tune the DMI with the spatial resolution of the\nAr+ irradiation enables new fundamental investigations and technological\napplications of chiral nanomagnetics."
    },
    {
        "anchor": "Ultra-low damping in lift-off structured yttrium iron garnet thin films: We show that using maskless photolithography and the lift-off technique,\npatterned yttrium iron garnet thin films possessing ultra-low Gilbert damping\ncan be accomplished. The films of 70 nm thickness were grown on (001)-oriented\ngadolinium gallium garnet by means of pulsed laser deposition, and they exhibit\nhigh crystalline quality, low surface roughness, and the effective\nmagnetization of 127 emu/cm3. The Gilbert damping parameter is as low as\n5x10-4. The obtained structures have well-defined sharp edges which along with\ngood structural and magnetic film properties pave a path in the fabrication of\nhigh-quality magnonic circuits and oxide-based spintronic devices.",
        "positive": "Mapping the full lattice strain tensor of a single dislocation by High\n  Angular Resolution Transmission Kikuchi Diffraction (HR-TKD): The full lattice strain tensor and lattice rotations induced by a dislocation\nin pure tungsten were mapped using high-resolution transmission Kikuchi\ndiffraction (HR-TKD) in a SEM. The HR-TKD measurement agrees very well with a\nforward calculation using an elastically isotropic model of the dislocation and\nits Burgers vector. Our results demonstrate that the spatial and angular\nresolution of HR-TKD in SEM is sufficiently high to resolve the details of\nlattice distortions near individual dislocations. This capability opens a\nnumber of new interesting opportunities, for example determining the Burgers\nvector of an unknown dislocation in a fast and straightforward way."
    },
    {
        "anchor": "A Generalized Ising Model for studying Alloy Evolution under Irradiation\n  and its use in Kinetic Monte Carlo Simulations: We derive an Ising Hamiltonian for kinetic simulations involving interstitial\nand vacancy defects in binary alloys. Our model, which we term `ABVI',\nincorporates solute transport by both interstitial defects and vacancies into a\nmathematically-consistent framework , and thus represents a generalization to\nthe widely-used ABV model for alloy evolution simulations. The Hamiltonian\ncaptures the three possible interstitial configurations in a binary alloy: A-A,\nA-B, and B-B, which makes it particularly useful for irradiation damage\nsimulations. All the constants of the Hamiltonian are expressed in terms of\nbond energies that can be computed using first-principles calculations. We\nimplement our ABVI model in kinetic Monte Carlo simulations and perform a\nverification exercise by comparing our results to published irradiation damage\nsimulations in simple binary systems with Frenkel pair defect production and\nseveral microstructural scenarios, with matching agreement found.",
        "positive": "Carbonate-Bridged Dinuclear and Trinuclear Dysprosium(III)\n  Single-Molecule Magnets: In 2016, we reported a single-ion magnet [Dy(bbpen)Br] with an energy barrier\nover 1000 K. Here a dimeric [Dy2(mu-CO3)(bbpen)2(H2O)].H2O.CH3OH (1) and a\ntrimeric [Dy3(mu3-CO3)(bppen)3](CF3SO3).H2O (2) single-molecule magnets (SMMs)\nwere obtained through replacing the Br- anion with the carbonate bridge. Their\neffective relaxation barriers at zero dc field are decrease to 51 K and 422 K,\nrespectively, which are consist with their structural modifications."
    },
    {
        "anchor": "Elastic properties of dense hard-sphere fluids: A new analysis of elastic properties of dense hard sphere (HS) fluids is\npresented, based on the expressions derived by Miller [J. Chem. Phys. {\\bf 50},\n2733 (1969)]. Important consequences for HS fluids in terms of sound waves\npropagation, Poisson's ratio, Stokes-Einstein relation, and generalized Cauchy\nidentity are explored. Conventional expressions for high-frequency elastic\nmoduli for simple systems with continuous and differentiable interatomic\ninteraction potentials are known to diverge when approaching the HS repulsive\nlimit. The origin of this divergence is identified here. It is demonstrated\nthat these conventional expressions are only applicable for sufficiently soft\ninteractions and should not be applied to HS systems. The reported results can\nbe of interest in the context of statistical physics, physics of fluids, soft\ncondensed matter, and granular materials.",
        "positive": "High Dielectric Permittivity in AFe$_{1 / 2}$B$_{1 / 2}$O$_{3}$\n  Nonferroelectric Perovskite Ceramics (A - Ba, Sr, Ca; B - Nb, Ta, Sb): AFe$_{1 / 2}$B$_{1 / 2}$O$_{3}$(A- Ba, Sr, Ca; B-Nb, Ta, Sb) ceramics were\nsynthesized and temperature dependencies of the dielectric permittivity were\nmeasured at different frequencies. The experimental data obtained show very\nhigh values of the dielectric permittivity in a wide temperature interval that\nis inherent to so-called high-k materials. The analyses of these data establish\na Maxwell-Wagner mechanism as a main source for the phenomenon observed."
    },
    {
        "anchor": "Impact of the domain structure in ferroelectric substrate on graphene\n  conductance (authors' review): Review is devoted to the recent theoretical studies of the impact of domain\nstructure of ferroelectric substrate on graphene conductance. An analytical\ndescription of the hysteresis memory effect in a field effect transistor based\non graphene-on-ferroelectric, taking into account absorbed dipole layers on the\nfree surface of graphene and localized states on its interfaces is considered.\nThe aspects of the recently developed theory of p-n junctions conductivity in a\ngraphene channel on a ferroelectric substrate, which are created by a\n180-degree ferroelectric domain structure, are analyzed, and cases of different\ncurrent regimes from ballistic to diffusion one are considered. The influence\nof size effects in such systems and the possibility of using the results for\nimproving the characteristics of field effect transistors with a graphene\nchannel, non-volatile ferroelectric memory cells with random access, sensors,\nas well as for miniaturization of various devices of functional nanoelectronics\nare discussed.",
        "positive": "Further Comments on the replies given by Yoshihiko Yokoyama and Akihisa\n  Inoue (Mater. Trans. 50 (2009) 2504-2506.) for Tsuyoshi Kajitani (Mater.\n  Trans. 50 (2009) 2502-2503.): Yokoyama and Inoue gabe their replies to eight questions raised by the\npresent author with respect to their paper on \"Production of Zr55Cu30Ni5Al10\nglassy alloy rod of 30mm in diameter by a cap-cast technique\" in 2007. Yokoyama\nand Inoue stressed in their reply that there were no inadequeate descriptions\nin their paper, except for the catalog name of a TEM machine, which was a\ntypographical error. It is still unclear why a cap-cast technique is needed to\nproduce glassy alloy rods up to 30mm in diameter. Lack of essential information\nregarding the cap-cast technique leads us no valuable assessment of a new\ntechnique. Further questions arose."
    },
    {
        "anchor": "High-throughput nanoindentation mapping of cast IN718 nickel-based\n  superalloys: influence of the Nb concentration: A high-throughput correlative study of the local mechanical properties,\nchemical composition and crystallographic orientation has been carried out in\nselected areas of cast Inconel 718 specimens subjected to three different\ntempers. The specimens showed a strong Nb segregation at the scale of the\ndendrite arms, with local Nb contents that varied between 2 wt.% in the core of\nthe dendrite arms to 8 wt.% in the interdendritic regions and 25 wt.% within\nthe second phase particles (MC carbides, Laves phases and {\\delta} phase\nneedles). The nanohardness was found to correlate strongly with the local Nb\ncontent and the temper condition. On the contrary, the indentation elastic\nmoduli were not influenced by the local chemical composition or temper\ncondition, but directly correlated with the crystallographic grain orientation,\ndue to the high elastic anisotropy of nickel alloys.",
        "positive": "Detection of defect-induced magnetism in low-dimensional ZnO structures\n  by Magnetophotocurrent: The detection of defect-induced magnetic order in single low-dimensional\noxide structures is in general difficult because of the relatively small yield\nof magnetically ordered regions. In this work we have studied the effect of an\nexternal magnetic field on the transient photocurrent measured after light\nirradiation on different ZnO samples at room temperature. We found that a\nmagnetic field produces a change in the relaxation rate of the transient\nphotocurrent only in magnetically ordered ZnO samples. This rate can decrease\nor increase with field depending whether the magnetic order region is in the\nbulk or only at the surface of the ZnO sample. The phenomenon reported here is\nof importance for the development of magneto-optical low-dimensional oxides\ndevices and provide a new guideline for the detection of magnetic order in\nlow-dimensional magnetic semiconductors."
    },
    {
        "anchor": "Probing the shape of atoms in real space: The structure of single atoms in real space is investigated by scanning\ntunneling microscopy. Very high resolution is possible by a dramatic reduction\nof the tip-sample distance. The instabilities which are normally encountered\nwhen using small tip-sample distances are avoided by oscillating the tip of the\nscanning tunneling microscope vertically with respect to the sample. The\nsurface atoms of Si(111)-(7 x 7) with their well-known electronic configuration\nare used to image individual samarium, cobalt, iron and silicon atoms. The\nresulting images resemble the charge density corresponding to 4f, 3d and 3p\natomic orbitals.",
        "positive": "First-principles ionized-impurity scattering and charge transport in\n  doped materials: Scattering of carriers with ionized impurities governs charge transport in\ndoped semiconductors. However, electron interactions with ionized impurities\ncannot be fully described with quantitative first-principles calculations, so\ntheir understanding relies primarily on simplified models. Here we show an ab\ninitio approach to compute the interactions between electrons and ionized\nimpurities or other charged defects. It includes the short- and long-range\nelectron-defect (e-d) interactions on equal footing, and allows for efficient\ninterpolation of the e-d matrix elements. We combine the e-d and\nelectron-phonon interactions in the Boltzmann transport equation to compute the\ncarrier mobilities in doped silicon over a wide range of temperature and doping\nconcentrations, spanning seamlessly the defect- and phonon-limited transport\nregimes. The individual contributions of the defect- and phonon-scattering\nmechanisms to the carrier relaxation times and mean-free paths are analyzed.\nOur method provides a powerful tool to study electronic interactions in doped\nmaterials. It broadens the scope of first-principles transport calculations,\nenabling studies of a wide range of doped semiconductors and oxides with\napplication to electronics, energy and quantum technologies."
    },
    {
        "anchor": "Evidence of local magnetic order in hcp iron from Raman mode splitting: Experimental measurements of Raman spectra for hcp iron at high pressure show\ntwo modes over a considerable pressure range in contrast to the prediction of\none doubly degenerate mode for the hcp lattice. We use density functional\ntheory to investigate the influence of magnetic order on the Raman active modes\nof hcp iron. We find an antiferromagnetic state that lifts the degeneracy of\nthe transverse optical mode, and yields stable antiferromagnetic moments up to\napproximately 60 GPa (55 Bohr$^3$). The resulting frequencies of the two\ntransverse optical modes are in good agreement with the experimental Raman\nshifts, lending support to the existence of local antiferromagnetic order in\nhcp iron.",
        "positive": "Possible origin of the absence of magnetic order in LiOsO$_3$:\n  Spin-orbit coupling controlled ground state: LiOsO$_3$ is the first experimentally confirmed polar metal with\nferroelectric-like distortion. One puzzling experimental fact is its\nparamagnetic state down to very low temperature with negligible magnetic\nmoment, which is anomalous considering its $5d^3$ electron configuration since\nother osmium oxides (e.g. NaOsO$_3$) with $5d^3$ Os ions are magnetic. Here the\nmagnetic and electronic properties of LiOsO$_3$ are re-investigated carefully\nusing the first-principles density functional theory. Our calculations reveal\nthat the magnetic state of LiOsO$_3$ can be completely suppressed by the\nspin-orbit coupling. The subtle balance between significant spin-orbit coupling\nand weak Hubbard $U$ of $5d$ electrons can explain both the nonmagnetic\nLiOsO$_3$ and magnetic NaOsO$_3$. Our work provides a reasonable understanding\nof the long-standing puzzle of magnetism in some osmium oxides."
    },
    {
        "anchor": "Prospect for room temperature tunneling anisotropic magnetoresistance\n  effect: density of states anisotropies in CoPt systems: Tunneling anisotropic magnetoresistance (TAMR) effect, discovered recently in\n(Ga,Mn)As ferromagnetic semiconductors, arises from spin-orbit coupling and\nreflects the dependence of the tunneling density of states in a ferromagnetic\nlayer on orientation of the magnetic moment. Based on ab initio relativistic\ncalculations of the anisotropy in the density of states we predict sizable TAMR\neffects in room-temperature metallic ferromagnets. This opens prospect for new\nspintronic devices with a simpler geometry as these do not require\nantiferromagnetically coupled contacts on either side of the tunnel junction.\nWe focus on several model systems ranging from simple hcp-Co to more complex\nferromagnetic structures with enhanced spin-orbit coupling, namely bulk and\nthin film L1$_0$-CoPt ordered alloys and a monatomic-Co chain at a Pt surface\nstep edge. Reliability of the predicted density of states anisotropies is\nconfirmed by comparing quantitatively our ab initio results for the\nmagnetocrystalline anisotropies in these systems with experimental data.",
        "positive": "Simplified modelling of chiral lattice materials with local resonators: A simplified model of periodic chiral beam-lattices containing local\nresonators has been formulated to obtain a better understanding of the\ninfluence of the chirality and of the dynamic characteristics of the local\nresonators on the acoustic behavior. The simplified beam-lattices is made up of\na periodic array of rigid heavy rings, each one connected to the others through\nelastic slender massless ligaments and containing an internal resonator made of\na rigid disk in a soft elastic annulus. The band structure and the occurrence\nof low frequency band-gaps are analysed through a discrete Lagrangian model.\nFor both the hexa- and the tetrachiral lattice, two acoustic modes and four\noptical modes are identified and the influence of the dynamic characteristics\nof the resonator on those branches is analyzed together with some properties of\nthe band structure. By approximating the generalized displacements of the rings\nof the discrete Lagrangian model as a continuum field and through an\napplication of the generalized macro-homogeneity condition, a generalized\nmicropolar equivalent continuum has been derived, together with the overall\nequation of motion and the constitutive equation given in closed form. The\nvalidity limits of the micropolar model with respect to the dispersion\nfunctions are assessed by comparing the dispersion curves of this model in the\nirreducible Brillouin domain with those obtained by the discrete model, which\nare exact within the assumptions of the proposed simplified model."
    },
    {
        "anchor": "Electrical current distribution across a metal-insulator-metal structure\n  during bistable switching: Combining scanning electron microscopy (SEM) and electron-beam-induced\ncurrent (EBIC) imaging with transport measurements, it is shown that the\ncurrent flowing across a two-terminal oxide-based capacitor-like structure is\npreferentially confined in areas localized at defects. As the thin-film device\nswitches between two different resistance states, the distribution and\nintensity of the current paths, appearing as bright spots, change. This implies\nthat switching and memory effects are mainly determined by the conducting\nproperties along such paths. A model based on the storage and release of charge\ncarriers within the insulator seems adequate to explain the observed memory\neffect.",
        "positive": "Single-carrier impact ionization favored by a limited band dispersion: A critical requirement for high gain and low noise avalanche photodiodes is\nthe single-carrier avalanche multiplication. We propose that the single-carrier\navalanche multiplication can be achieved in materials with a limited width of\nthe conduction or valence band resulting in a restriction of kinetic energy for\none of the charge carriers. This feature is not common to the majority of\ntechnologically relevant semiconductors, but it is observed in chalcogenides,\nsuch as Selenium and compound I2-II-IV-VI4 alloys."
    },
    {
        "anchor": "Instabilities in crystal growth by atomic or molecular beams: The planar front of a growing a crystal is often destroyed by instabilities.\nIn the case of growth from a condensed phase, the most frequent ones are\ndiffusion instabilities, which will be but briefly discussed in simple terms in\nchapter II. The present review is mainly devoted to instabilities which arise\nin ballistic growth, especially Molecular Beam Epitaxy (MBE). The reasons of\nthe instabilities can be geometric (shadowing effect), but they are mostly\nkinetic or thermodynamic. The kinetic instabilities which will be studied in\ndetail in chapters IV and V result from the fact that adatoms diffusing on a\nsurface do not easily cross steps (Ehrlich-Schwoebel or ES effect). When the\ngrowth front is a high symmetry surface, the ES effect produces mounds which\noften coarsen in time according to power laws. When the growth front is a\nstepped surface, the ES effect initially produces a meandering of the steps,\nwhich eventually may also give rise to mounds. Kinetic instabilities can\nusually be avoided by raising the temperature, but this favours thermodynamic\ninstabilities. Concerning these ones, the attention will be focussed on the\ninstabilities resulting from slightly different lattice constants of the\nsubstrate and the adsorbate. They can take the following forms. i) Formation of\nmisfit dislocations (chapter VIII). ii) Formation of isolated epitaxial\nclusters which, at least in their earliest form, are `coherent' with the\nsubstrate, i.e. dislocation-free (chapter X). iii) Wavy deformation of the\nsurface, which is presumably the incipient stage of (ii) (chapter IX). The\ntheories and the experiments are critically reviewed and their comparison is\nqualitatively satisfactory although some important questions have not yet\nreceived a complete answer.",
        "positive": "Pressure formulas for liquid metals and plasmas based on the\n  density-functional theory: At first, pressure formulas for the electrons under the external potential\nproduced by fixed nuclei are derived both in the surface integral and volume\nintegral forms concerning an arbitrary volume chosen in the system; the surface\nintegral form is described by a pressure tensor consisting of a sum of the\nkinetic and exchange-correlation parts in the density-functional theory, and\nthe volume integral form represents the virial theorem with subtraction of the\nnuclear virial. Secondly on the basis of these formulas, the thermodynamical\npressure of liquid metals and plasmas is represented in the forms of the\nsurface integral and the volume integral including the nuclear contribution.\n  From these results, we obtain a virial pressure formula for liquid metals,\nwhich is more accurate and simpler than the standard representation. From the\nview point of our formulation, some comments are made on pressure formulas\nderived previously and on a definition of pressure widely used."
    },
    {
        "anchor": "Total energy calculation for the metallic hcp phase of Zn in the bulk,\n  layered, and quantum dot limits: The structural and electronic properties of the metallic hcp phase of Zn in\nthe bulk, monolayer, bilayer, and quantum dot limits have been studied by using\ntotal energy calculations. From our calculated density of states and electronic\nband structure, in agreement with previous work, bulk hybridization of the\nZn--$4s$, $3p$, and $3d$ orbitals is obtained. Furthermore, we found that this\norbital hybridization is also obtained for the monolayer, bilayer, and quantum\ndot systems. At the same time, we found that the Zn monolayer and bilayer\nsystems show electronic properties characteristic of lamellar systems, while\nthe quantum dot system shows the behavior predicted for a 0D system.",
        "positive": "Computing the energy of a water molecule using MultiDeterminants: A\n  simple, efficient algorithm: Quantum Monte Carlo (QMC) methods such as variational Monte Carlo and fixed\nnode diffusion Monte Carlo depend heavily on the quality of the trial wave\nfunction. Although Slater-Jastrow wave functions are the most commonly used\nvariational ansatz in electronic structure, more sophisticated wave-functions\nare critical to ascertaining new physics. One such wave function is the\nmultiSlater-Jastrow wave function which consists of a Jastrow function\nmultiplied by the sum of Slater determinants. In this paper we describe a\nmethod for working with these wavefunctions in QMC codes that is easy to\nimplement, efficient both in computational speed as well as memory, and easily\nparallelized. The computational cost scales quadratically with particle number\nmaking this scaling no worse than the single determinant case and linear with\nthe total number of excitations. Additionally we implement this method and use\nit to compute the ground state energy of a water molecule."
    },
    {
        "anchor": "Controlled healing of graphene nanopores: Nanopores of nanometer-size holes are very promising devices for many\napplications: DNA sequencing, sensory, biosensoring and molecular detectors,\ncatalysis and water desalination. These applications require accurate control\nover nanopores size. We report computer simulation studies of regrowth and\nhealing of graphene nanopores of different sizes ranging from 30 to 5 {\\AA}. We\nstudy mechanism, speed of nanopores regrowth and structure of healed areas in\nthe wide range of temperatures. We report existence of at least two distinct\nhealing mechanisms, one so called edge attachment where carbons are attached to\nthe edges of graphene sheet and another mechanism that involves atom insertion\ndirectly into a sheet of graphene even in the absence of the edges. These\nfindings point a significantly more complicated pathways for graphene\nannealing. They also provide an important enabling step in development of\ngraphene based devices for numerous nanotechnology applications.",
        "positive": "The effect of the lateral interactions on the critical behavior of long\n  straight rigid rods on two-dimensional lattices: Using Monte Carlo simulations and finite-size scaling analysis, the critical\nbehavior of attractive rigid rods of length k (k-mers) on square lattices at\nintermediate density has been studied. A nematic phase, characterized by a big\ndomain of parallel k-mers, was found. This ordered phase is separated from the\nisotropic state by a continuous transition occurring at a intermediate density\n\\theta_c, which increases linearly with the magnitude of the lateral\ninteractions."
    },
    {
        "anchor": "All-electron GW calculation based on the LAPW method: application to\n  wurtzite ZnO: We present a new, all-electron implementation of the GW approximation and\napply it to wurtzite ZnO. Eigenfunctions computed in the local-density\napproximation (LDA) by the full-potential linearized augmented-plane-wave\n(LAPW) or the linearized muffin-tin-orbital (LMTO) method supply the input for\ngenerating the Green function G and the screened Coulomb interaction W. A mixed\nbasis is used for the expansion of W, consisting of plane waves in the\ninterstitial region and augmented-wavefunction products in the\naugmentation-sphere regions. The frequency-dependence of the dielectric\nfunction is computed within the random-phase approximation (RPA), without a\nplasmon-pole approximation. The Zn 3d orbitals are treated as valence states\nwithin the LDA; both core and valence states are included in the self-energy\ncalculation. The calculated bandgap is smaller than experiment by about 1eV, in\ncontrast to previously reported GW results. Self-energy corrections are\norbital-dependent, and push down the deep O 2s and Zn 3d levels by about 1eV\nrelative to the LDA. The d level shifts closer to experiment but the size of\nshift is underestimated, suggesting that the RPA overscreens localized states.",
        "positive": "Charge-induced effects on the structure and properties of silane and\n  disilane derivatives: Using ab-initio electronic structure methods we have investigated the ground\nstate structures and properties of neutral and charged SiH$_{m}$(m=1-4) and\nSi$_{2}$H$_{n}$(n=1-6) clusters which are produced in the plasma enhanced\nchemical vapor deposition process used in the preparation of hydrogenated\namorphous silicon({\\it{a}}-Si:H). Our results show that charging a neutral\ncluster distorts it and the distortion mainly occurs through the orientation of\nSi-H bond. We attribute structural changes in the charged clusters to\nelectrostatic repulsion between the bonded and non-bonded electrons. We find\nthat in addition to the usual Si-H bond, hydrogen atoms form Si-H-H and Si-H-Si\nbonds in some clusters. The vibrations of\n  Si-H, Si-Si, Si-H-Si bond stretching modes show that the frequencies are\nshifted significantly upon charging. The frequency shifts in the charged\nclusters are consistent with their bond length variations. We discuss the\nfragmentation pathways of silane into binary products and the role of\nfragmented silane radicals in the cluster formation and {\\it{a}}-Si:H film\ndeposition process."
    },
    {
        "anchor": "Spin-polarized tunneling spectroscopy in tunnel junctions with\n  half-metallic electrodes: We have studied the magnetoresistance (TMR) of tunnel junctions with\nelectrodes of La2/3Sr1/3MnO3 and we show how the variation of the conductance\nand TMR with the bias voltage can be exploited to obtain a precise information\non the spin and energy dependence of the density of states. Our analysis leads\nto a quantitative description of the band structure of La2/3Sr1/3MnO3 and\nallows the determination of the gap delta between the Fermi level and the\nbottom of the t2g minority spin band, in good agreement with data from\nspin-polarized inverse photoemission experiments. This shows the potential of\nmagnetic tunnel junctions with half-metallic electrodes for spin-resolved\nspectroscopic studies.",
        "positive": "Correlation effects in the electronic structure of Mn$_4$ molecular\n  magnet: We present joint theoretical-experimental study of the correlation effects in\nthe electronic structure of (pyH)$_3$[Mn$_4$O$_3$Cl$_7$(OAc)$_3$]$\\cdot$2MeCN\nmolecular magnet (Mn$_4$). Describing the many-body effects by cluster\ndynamical mean-field theory, we find that Mn$_4$ is predominantly Hubbard\ninsulator with strong electron correlations. The calculated electron gap (1.8\neV) agrees well with the results of optical conductivity measurements, while\nother methods, which neglect many-body effects or treat them in a simplified\nmanner, do not provide such an agreement. Strong electron correlations in\nMn$_4$ may have important implications for possible future applications."
    },
    {
        "anchor": "Tri-branched gels: Rubbery materials with the lowest branching factor\n  approach the ideal elastic limit: Unlike hard materials such as metals and ceramics, rubbery materials can\nendure large deformations due to the large conformational degree of freedom of\nthe crosslinked three-dimensional polymer network. However, the effect of the\nbranching factor of the network on the ultimate mechanical properties of\nrubbery materials has not yet been clarified. This study shows that\ntri-branching, which entails the lowest branching factor, results in a large\nelastic deformation near the theoretical upper bound. This ideal elastic limit\nis realized by reversible strain-induced crystallization, providing on-demand\nreinforcement. The findings indicate that the polymer chain is highly\norientated along the stretching axis, whereat enhanced reversible\nstrain-induced crystallization is observed in the tri-branched and not in the\ntetra-branched network. A mathematical theory of structural rigidity is used to\nexplain the difference in the chain orientation. Although tetra-branched\npolymers have been preferred since the development of vulcanization, these\nfindings highlighting the merits of tri-branching will prompt a paradigm shift\nin the development of rubbery materials.",
        "positive": "Non-linear optical susceptibilities, Raman efficiencies and electrooptic\n  tensors from first-principles density functional perturbation theory: The non-linear response of infinite periodic solids to homogenous electric\nfields and collective atomic displacements is discussed in the framework of\ndensity functional perturbation theory. The approach is based on the 2n + 1\ntheorem applied to an electric-field-dependent energy functional. We report the\nexpressions for the calculation of the non-linear optical susceptibilities,\nRaman scattering efficiencies and electrooptic coefficients. Different\nformulations of third-order energy derivatives are examined and their\nconvergence with respect to the k-point sampling is discussed. We apply our\nmethod to a few simple cases and compare our results to those obtained with\ndistinct techniques. Finally, we discuss the effect of a scissors correction on\nthe EO coefficients and non-linear optical susceptibilities."
    },
    {
        "anchor": "Magnon modes and magnon-vortex scattering in two-dimensional easy-plane\n  ferromagnets: We calculate the magnon modes in the presence of a vortex in a circular\nsystem, combining analytical calculations in the continuum limit with a\nnumerical diagonalization of the discrete system. The magnon modes are\nexpressed by the S-matrix for magnon-vortex scattering, as a function of the\nparameters and the size of the system and for different boundary conditions.\nCertain quasi-local translational modes are identified with the frequencies\nwhich appear in the trajectory X(t) of the vortex center in recent Molecular\nDynamics simulations of the full many-spin model. Using these quasi-local modes\nwe calculate the two parameters of a 3rd-order quation of motion for X(t). This\nequation was recently derived by a collective variable theory and describes\nvery well the trajectories observed in the simulations. Both parameters, the\nvortex mass and a factor on the third time derivative of X(t), depend strongly\non the boundary conditions.",
        "positive": "Pulsed-mode metalorganic vapor-phase epitaxy of GaN on graphene-coated\n  c-sapphire for freestanding GaN thin films: We report the growth of high-quality GaN epitaxial thin films on\ngraphene-coated c-sapphire substrates using pulsed-mode metalorganic\nvapor-phase epitaxy, together with the fabrication of freestanding GaN films by\nsimple mechanical exfoliation for transferable light-emitting diodes (LEDs).\nHigh-quality GaN films grown on the graphene-coated sapphire substrates were\neasily lifted off using thermal release tape and transferred onto foreign\nsubstrates. Furthermore, we revealed that the pulsed operation of ammonia flow\nduring GaN growth was a critical factor for the fabrication of high-quality\nfreestanding GaN films. These films, exhibiting excellent single crystallinity,\nwere utilized to fabricate transferable GaN LEDs by heteroepitaxially growing\nInxGa1-xN/GaN multiple quantum wells and a p-GaN layer on the GaN films,\nshowing their potential application in advanced optoelectronic devices."
    },
    {
        "anchor": "Polarization conversion spectroscopy of hybrid modes: Enhanced polarization conversion in reflection for the Otto and Kretschmann\nconfigurations is introduced as a new method for hybrid-mode spectroscopy.\nPolarization conversion in reflection appears when hybrid-modes are excited in\na guiding structure composed of at least one anisotropic media. In contrast to\na dark dip, in this case modes are associated to a peak in the converted\nreflectance spectrum, increasing the detection sensitivity and avoiding\nconfusion with reflection dips associated with other processes as can be\ntransmission.",
        "positive": "Giant piezoelectricity driven by Thouless pump in conjugated polymers: Piezoelectricity of organic polymers has attracted increasing interest\nbecause of several advantages they exhibit over traditional inorganic ceramics.\nWhile most organic piezoelectrics rely on the presence of intrinsic local\ndipoles, a highly nonlocal electronic polarization can be foreseen in\nconjugated polymers, characterised by delocalized and highly responsive\n${\\pi}$-electrons. These 1D systems represent a physical realization of a\nThouless pump, a mechanism of adiabatic charge transport of topological nature\nwhich results, as shown in this work, in anomalously large dynamical effective\ncharges, inversely proportional to the band gap energy. A structural\n(ferroelectric) phase transition further contributes to an enhancement of the\npiezoelectric response reminiscent of that observed in piezoelectric\nperovskites close to morphotropic phase boundaries. First-principles Density\nFunctional Theory (DFT) calculations performed in two representative conjugated\npolymers using hybrid functionals, show that state-of-the-art organic\npiezoelectric are outperformed by piezoelectric conjugated polymers, mostly\nthanks to strongly anomalous effective charges of carbon, larger than 5e -\nordinary values being of the order of 1e - and reaching the giant value of 30e\nfor band gaps of the order of 1 eV."
    },
    {
        "anchor": "Electron spin resonance of nitrogen-vacancy centers in optically trapped\n  nanodiamonds: Using an optical tweezers apparatus, we demonstrate three-dimensional control\nof nanodiamonds in solution with simultaneous readout of ground-state\nelectron-spin resonance (ESR) transitions in an ensemble of diamond\nnitrogen-vacancy (NV) color centers. Despite the motion and random orientation\nof NV centers suspended in the optical trap, we observe distinct peaks in the\nmeasured ESR spectra qualitatively similar to the same measurement in bulk.\nAccounting for the random dynamics, we model the ESR spectra observed in an\nexternally applied magnetic field to enable d.c. magnetometry in solution. We\nestimate the d.c. magnetic field sensitivity based on variations in ESR line\nshapes to be ~50 microTesla/Hz^1/2. This technique may provide a pathway for\nspin-based magnetic, electric, and thermal sensing in fluidic environments and\nbiophysical systems inaccessible to existing scanning probe techniques.",
        "positive": "Unexpected Anisotropic Two Dimensional Electron Gas at the LaAlO3/SrTiO3\n  (110) Interface: The observation of a two dimensional electron gas (2DEG) (1, 2),\nsuperconductivity (3, 4), magnetic effects (5) and electronic phase separation\n(6-8) at the interfaces of insulating oxides, especially LaAlO3/SrTiO3, has\nfurther enhanced the potential of complex oxides for novel electronics. The\noccurrence of the 2DEG is strongly believed to be driven by the polarization\ndiscontinuity (9) at the interface between the two oxides. In this scenario,\nthe crystal orientation plays an important role and no conductivity would be\nexpected for e.g., the interface between LaAlO3 and (110)-oriented SrTiO3,\nwhich should not have a polarization discontinuity (10, 11). Here, we report\nthe observation of unexpected conductivity at the LaAlO3/SrTiO3 interface\nprepared on (110)-oriented SrTiO3. The conductivity was further found to be\nstrongly anisotropic, with the ratio of the conductance along the different\ndirections parallel to the substrate surface showing a remarkable dependence on\nthe oxygen pressure during deposition. The conductance and its anisotropy are\ndiscussed based on the atomic structure at the interface, as revealed by\nScanning Transmission Electron Microscopy (STEM) and further supported by\ndensity functional theory (DFT) calculations."
    },
    {
        "anchor": "X-ray spectra in magnetic van der Waals materials Fe$_3$GeTe$_2$,\n  CrI$_3$, and CrGeTe$_3$: a first-principles study: Using density functional theory (DFT) methods, we have calculated X-ray\nabsorption spectroscopy (XAS) and X-ray circular dichroism (XMCD) spectra in\nbulk and thin films of Fe$_3$GeTe$_2$, CrI$_3$, and CrGeTe$_3$. DFT+$U$ methods\nare employed for better handling of correlation effects of 3$d$ electrons of\ntransition metals. We discuss relations between the density of states, radial\nmatrix elements, and the corresponding spectra. By comparing the calculated\nspectra with previously measured spectra, we discuss the reliability of DFT+$U$\nmethods to describe the electronic structures of these materials and determine\nthe corresponding optimal $U$ and $J$ parameters.",
        "positive": "Adsorbate-induced Surface Stiffening: Surface Lattice Dynamics of\n  Ru(001)-(1x1)-O: The dynamical properties of the high-density Ru(001)-(1$\\times$1)-O phase has\nbeen investigated by a combined high-resolution electron energy loss\nspectroscopy and density functional theory study. Due to a strong static\noutward relaxation of the first Ru layer a soft Rayleigh phonon mode is\nexpected. However, a Rayleigh mode stiffening together with a new high energy\nin-plane phonon mode above the bulk bands is found which is related to a strong\nadsorbate-induced intralayer force constant stiffening which counteracts an\ninterlayer softening. This structurally rather simple system with one surface\natom per (1$\\times$1) unit cell demonstrates the limited applicability of\npreviously adopted models."
    },
    {
        "anchor": "Spin dynamics in the strong spin-orbit coupling regime: We study the spin dynamics in a high-mobility two dimensional electron gas\n(2DEG) with generic spin-orbit interactions (SOIs). We derive a set of spin\ndynamic equations which capture the purely exponential to the damped\noscillatory spin evolution modes observed in different regimes of SOI strength.\nHence we provide a full treatment of the D'yakonov-Perel's mechanism by using\nthe microscopic linear response theory from the weak to the strong SOI limit.\nWe show that the damped oscillatory modes appear when the electron scattering\ntime is larger than half of the spin precession time due to the SOI, in\nagreement with recent observations. We propose a new way to measure the\nscattering time and the relative strength of Rashba and linear Dresselhaus SOIs\nbased on these modes and optical grating experiments. We discuss the physical\ninterpretation of each of these modes in the context of Rabi oscillation.",
        "positive": "Heterogeneous ice nucleation on silver-iodide-like surfaces: We attempt to simulate the heterogeneous nucleation of ice at model\nsilver-iodide surfaces and find relatively facile ice nucleation and growth at\nthe Ag+ termi nated basal face, but never see nucleation at the I- terminated\nbasal face or the prism and normal faces. Water molecules strongly adsorb onto\nthe Ag+ terminate d face to give a well-ordered hexagonal ice-like bilayer that\nthen acts as a template for further ice growth."
    },
    {
        "anchor": "Coupled magnetic and ferroelectric excitations in\n  PbFe_{1/2}Nb_{1/2}O_{3}: A neutron scattering investigation of the magnetoelectric coupling in\nPbFe_{1/2}Nb_{1/2}O_{3} (PFN) has been undertaken. Ferroelectric order occurs\nbelow 400 K, as evidenced by the softening with temperature and subsequent\nrecovery of the zone center transverse optic phonon mode energy (\\hbar\n\\Omega_{0}). Over the same temperature range, magnetic correlations become\nresolution limited on a terahertz energy scale. In contrast to the behavior of\nnonmagnetic disordered ferroelectrics (namely Pb(Mg,Zn)_{1/3}Nb_{2/3}O_{3}), we\nreport the observation of a strong deviation from linearity in the temperature\ndependence of (\\hbar \\Omega_{0})^{2}. This deviation is compensated by a\ncorresponding change in the energy scale of the magnetic excitations, as probed\nthrough the first moment of the inelastic response. The coupling between the\nshort-range ferroelectric and antiferromagnetic correlations is consistent with\ncalculations showing that the ferroelectricity is driven by the displacement of\nthe body centered iron site, illustrating the multiferroic nature of magnetic\nlead based relaxors in the dynamical regime.",
        "positive": "New Reversal Mode in Exchange Coupled Antiferromagnetic/Ferromagnetic\n  Disks: Distorted Viscous Vortex: Magnetic vortices have generated intense interest in recent years due to\ntheir unique reversal mechanisms, fascinating topological properties, and\nexciting potential applications. Additionally, the exchange coupling of\nmagnetic vortices to antiferromagnets has also been shown to lead to a range of\nnovel phenomena and functionalities. Here we report a new magnetization\nreversal mode of magnetic vortices in exchange coupled Ir20Mn80/Fe20Ni80\nmicrodots: distorted viscous vortex reversal. Contrary to the previously known\nor proposed reversal modes, the vortex is distorted close to the interface and\nviscously dragged due to the uncompensated spins of a thin antiferromagnet,\nwhich leads to unexpected asymmetries in the annihilation and nucleation\nfields. These results provide a deeper understanding of the physics of exchange\ncoupled vortices and may also have important implications for applications\ninvolving exchange coupled nanostructures."
    },
    {
        "anchor": "Atomic scale evolution of the surface chemistry in Li[Ni,Mn,Co]O2\n  cathode for Li-ion batteries stored in air: Layered LiMO2 (M = Ni, Co, Mn, and Al mixture) cathode materials used for\nLi-ion batteries are reputed to be highly reactive through their surface, where\nthe chemistry changes rapidly when exposed to ambient air. However,\nconventional electron/spectroscopy-based techniques or thermogravimetric\nanalysis fails to capture the underlying atom-scale chemistry of vulnerable Li\nspecies. To study the evolution of the surface composition at the atomic scale,\nhere we use atom probe tomography and probed the surface species formed during\nexposure of a LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode material to air. The\ncompositional analysis evidences the formation of Li2CO3. Site specific\nexamination from a cracked region of an NMC811 particle also suggests the\npredominant presence of Li2CO3. These insights will help to design improved\nprotocols for cathode synthesis and cell assembly, as well as critical\nknowledge for cathode degradation",
        "positive": "Germanium Segregation in CVD Grown Sige Layers for Flash Memory\n  Application: A 2D layer of spherical, crystalline Ge nanodots embedded in SiO2 was formed\nby low pressure chemical vapour deposition combined with furnace oxidation and\nrapid thermal annealing. The samples were characterized structurally by using\ntransmission electron microscopy and rutherford back scattering spectrometry,\nas well as electrically by measuring CV and IV characteristics. It was found\nthat formation of a high density Ge dots took place due to oxidation induced Ge\nsegregation. The dots are situated in the SiO2 on the average distance 5 nm\nfrom the substrate. Strong evidence of charge storage effect in the crystalline\nGe nanodot layer is demonstrated by the hysteresis behavior of the high\nfrequency CV curves."
    },
    {
        "anchor": "Screening piezoelectricity in determination of flexoelectric coefficient\n  at nanoscale: Piezoelectricity usually accompanies with flexoelectricity in polar materials\nwhich is the linear response of polarization to a strain gradient. Therefore,\nit is hard to eliminate piezoelectric effect in determination of pure\nflexoelectric response. In this work, we propose an analytical method to\ncharacterize the flexoelectric coefficient quantitatively at nanoscale in\npiezoelectric materials by screening piezoelectricity. Our results show that\nthe flexoelectricity reduces the nanopillar stiffness while the\npiezoelectricity enhances it. With careful design of the shape of the\nnanopillars and measuring their stiffness difference, the flexoelectric\ncoefficient can be obtained with the piezoelectric contribution eliminated\ncompletely. This approach avoids the measurement of electrical properties with\ndynamic load, which helps to reduce the challenge of flexoelectric measurement\nat nanoscale. Our work will be beneficial to quantitative characterization of\nflexoelectric properties and design of flexoelectric devices at nanoscale.",
        "positive": "Ultrafast ferromagnetic fluctuations preceding magnetoelastic\n  first-order transitions: First-order magnetic transitions are of both fundamental and technological\ninterest given that a number of emergent phases and functionalities are thereby\ncreated. Of particular interest are giant magnetocaloric effects, which are\nattributed to first-order magnetic transitions and have attracted broad\nattention for solid-state refrigeration applications. While the conventional\nwisdom is that atomic lattices play an important role in first-order magnetic\ntransitions, a coherent microscopic description of the lattice and spin degrees\nof freedom is still lacking. Here, we study the magnetic phase transition\ndynamics on the intermetallic LaFe13-xSix, which is one of the most classical\ngiant magnetocaloric systems, in both frequency and time domains utilizing\nneutron scattering and ultrafast X-ray diffraction. We have observed a strong\nmagnetic diffuse scattering in the paramagnetic state preceding the first-order\nmagnetic transition, corresponding to picosecond ferromagnetic fluctuations.\nUpon photon-excitation, the ferromagnetic state is completely suppressed in 0.9\nps and recovered in 20 ps. The ultrafast dynamics suggest that the magnetic\ndegree of freedom dominates this magnetoelastic transition and ferromagnetic\nfluctuations might be universally relevant for this kind of compounds."
    },
    {
        "anchor": "Magnetism without magnetic impurities in oxides ZrO2 and TiO2: We perform a theoretical study of the magnetism induced in transition metal\ndioxides ZrO2 and TiO2 by substitution of the cation by a vacancy or an\nimpurity from the groups 1A or 2A of the periodic table, where the impurity is\neither K or Ca. In the present study both supercell and embedded cluster\nmethods are used. It is demonstrated that the vacancy and the K-impurity leads\nto a robust induced magnetic moment on the surrounding O-atoms for both the\ncubic ZrO2 and rutile TiO2 host crystals. On the other hand it is shown that\nCa-impurity leads to a non magnetic state. The native O-vacancy does not induce\na magnetic moment in the host dioxide crystal.",
        "positive": "First-principles theory of giant Rashba-like spin-splitting in bulk\n  ferroelectrics: Recently large Rashba-like spin splitting has been observed in certain bulk\nferroelectrics. In contrast with the relativistic Rashba effect, the chiral\nspin texture and large spin-splitting of the electronic bands depend strongly\non the character of the band and atomic spin-orbit coupling. We establish that\nthis can be traced back to the so-called orbital Rashba effect, also in the\nbulk. This leads to an additional dependence on the orbital composition of the\nbands, which is crucial for a complete picture of the effect. Results from\nfirst-principles calculations on ferroelectic GeTe verify the key predictions\nof the model."
    },
    {
        "anchor": "Tuning the Polar States of Ferroelectric Films via Surface Charges and\n  Flexoelectricity: Using the self-consistent Landau-Ginzburg-Devonshire approach we simulate and\nanalyze the spontaneous formation of the domain structure in thin ferroelectric\nfilms covered with the surface screening charge of the specific nature\n(Bardeen-type surface states). Hence we consider the competition between the\nscreening and the domain formation as alternative ways to reduce the\nelectrostatic energy and reveal unusual peculiarities of distributions of\npolarization, electric and elastic fields conditioned by the surface screening\nlength and the flexocoupling strength. We have established that the critical\nthickness of the film and its transition temperature to a paraelectric phase\nstrongly depend on the Bardeen screening length, while the flexocoupling\naffects the polarization rotation and closure domain structure and induces\nribbon-like nano-scale domains in the film depth far from the top open surface.\nHence the joint action of the surface screening (originating from e.g. the\nadsorption of ambient ions or surface states) and flexocoupling may remarkably\nmodify polar and electromechanical properties of thin ferroelectric films.",
        "positive": "Nonlinear bias dependence of spin-transfer torque from atomic first\n  principles: We report first-principles analysis on the bias dependence of spin-transfer\ntorque (STT) in Fe/MgO/Fe magnetic tunnel junctions. The in-plane STT changes\nfrom linear to nonlinear dependence as the bias voltage is increased from zero.\nThe angle dependence of STT is symmetric at low bias but asymmetric at high\nbias. The nonlinear behavior is marked by a threshold point in the STT versus\nbias curve. The high-bias nonlinear STT is found to be controlled by a resonant\ntransmission channel in the anti-parallel configuration of the magnetic\nmoments. Disorder scattering due to oxygen vacancies in MgO significantly\nchanges the STT threshold bias."
    },
    {
        "anchor": "Wide-range optical studies on various single-walled carbon nanotubes:\n  the origin of the low-energy gap: We present wide-range (3 meV - 6 eV) optical studies on freestanding\ntransparent carbon nanotube films, made from nanotubes with different diameter\ndistributions. In the far-infrared region, we found a low-energy gap in all\nsamples investigated. By a detailed analysis we determined the average\ndiameters of both the semiconducting and metallic species from the near\ninfrared/visible features of the spectra. Having thus established the\ndependence of the gap value on the mean diameter, we find that the frequency of\nthe low energy gap is increasing with increasing curvature. Our results\nstrongly support the explanation of the low-frequency feature as arising from a\ncurvature-induced gap instead of effective medium effects. Comparing our\nresults with other theoretical and experimental low-energy gap values, we find\nthat optical measurements yield a systematically lower gap than tunneling\nspectroscopy and DFT calculations, the difference increasing with decreasing\ndiameter. This difference can be assigned to electron-hole interactions.",
        "positive": "Nonlinear anomalous photocurrents in Weyl semimetals: We study the second-order nonlinear optical response of a Weyl semimetal\n(WSM), i.e. a three-dimensional metal with linear band touchings acting as\npoint-like sources of Berry curvature in momentum space, termed \"Weyl-Berry\nmonopoles\". We first show that the anomalous second-order photocurrent of WSMs\ncan be elegantly parametrized in terms of Weyl-Berry dipole and quadrupole\nmoments. We then calculate the corresponding charge and node conductivities of\nWSMs with either broken time-reversal invariance or inversion symmetry. In\nparticular, we predict a universal dissipationless second-order anomalous node\nconductivity for WSMs belonging to the TaAs family."
    },
    {
        "anchor": "About a first order transformation of magnetite at 1 160 \u00b0C: In the literature on the w{\\\"u}stite/magnetite transformation, there are two\ndistinct values of the enthalpy and entropy terms of the equilibrium between\nthese two oxides. The formalism established previously for the calculation of\nthermodynamic properties of w{\\\"u}stite is taken as well as the adjustment of\nthe boundary between the respective domains. A first-order transformation of\nthe magnetite is demonstrated at 1 433 K or 1 160{\\textdegree}C where the\nchange in the reference enthalpy is -9 990 J.mole-1 at heating, with the\ncorresponding entropy change being-6.89 J.K-1. . mole-1. The approximate\ndetermination of enthalpy vs temperature is made for both varieties of\nmagnetite. Two values of the molar heat content are deduced, with which a\ndirect experimental value can be compared.",
        "positive": "High-order harmonic generation in graphene: nonlinear coupling of intra\n  and interband transitions: We investigate high-order harmonic generation (HHG) in graphene with a\nquantum master equation approach. The simulations reproduce the observed\nenhancement in HHG in graphene under elliptically polarized light [N. Yoshikawa\net al, Science 356, 736 (2017)]. On the basis of a microscopic decomposition of\nthe emitted high-order harmonics, we find that the enhancement in HHG\noriginates from an intricate nonlinear coupling between the intraband and\ninterband transitions that are respectively induced by perpendicular electric\nfield components of the elliptically polarized light. Furthermore, we reveal\nthat contributions from different excitation channels destructively interfere\nwith each other. This finding suggests a path to potentially enhance the HHG by\nblocking a part of the channels and canceling the destructive interference\nthrough band-gap or chemical potential manipulation."
    },
    {
        "anchor": "First-principles approach to lattice-mediated magnetoelectric effects: We present a first-principles scheme for the computation of the\nmagnetoelectric response of magnetic insulators. The method focuses on the\nlattice-mediated part of the magnetic response to an electric field, which we\nargue can be expected to be the dominant contribution in materials displaying a\nstrong magnetoelectric coupling. We apply our method to Cr2O3, a relatively\nsimple and experimentally well studied magnetoelectric compound.",
        "positive": "Dispersion degeneracies and standing modes in flexural waves supported\n  by Rayleigh beam structures: The paper presents a novel analysis of Floquet-Bloch flexural waves in a\nperiodic lattice-like structure consisting of flexural beam ligaments. A\nspecial feature of this structure is in the presence of the rotational inertia,\nwhich is commonly neglected in conventional models of the Euler-Bernoulli type.\nThe dispersion properties of the Rayleigh beam structure with rotational\ninertia include degeneracies linked to Dirac cones on the dispersion diagrams\nas well as directional anisotropy and special refraction properties. Steering\nof Dirac cones is described for rectangular flexural structures with a\nrotational inertia. Numerical examples for a forced network of Rayleigh and\nEuler-Bernoulli beams illustrate directional localisation, negative refraction,\nlocalisation at an interface and neutrality for propagating plane waves across\na structured interface for a frequency range corresponding to a Dirac cone."
    },
    {
        "anchor": "Spin-wave modes and band structure of rectangular CoFeB antidot lattices: We present an investigation of rectangular antidot lattices in a CoFeB film.\nMagnonic band structures are numerically calculated, and band gaps are\npredicted which shift in frequency by 0.9 GHz when rotating the external field\nfrom the long to the short axis of the unit cell. We demonstrate by\ntime-resolved experiments that magnonic dipolar surface modes are split in\nfrequency by 0.6 GHz which agrees well with the theoretical prediction. These\nfindings provide the basis for directional spin-wave filtering with magnonic\ndevices.",
        "positive": "Intersystem Crossing and Exciton-Defect Coupling of Spin Defects in\n  Hexagonal Boron Nitride: Despite the recognition of two-dimensional (2D) systems as emerging and\nscalable host materials of single photon emitters or spin qubits, uncontrolled\nand undetermined chemical nature of these quantum defects has been a roadblock\nto further development. Leveraging the design of extrinsic defects can\ncircumvent these persistent issues and provide an ultimate solution. Here we\nestablished a complete theoretical framework to accurately and systematically\ndesign quantum defects in wide-bandgap 2D systems. With this approach,\nessential static and dynamical properties are equally considered for spin qubit\ndiscovery. In particular, many-body interactions such as defect-exciton\ncouplings are vital for describing excited state properties of defects in\nultrathin 2D systems. Meanwhile, nonradiative processes such as phonon-assisted\ndecay and intersystem crossing rates require careful evaluation, which compete\ntogether with radiative processes. From a thorough screening of defects based\non first-principles calculations, we identify promising single photon emitters\nsuch as SiVV and spin qubits such as TiVV and MoVV in hexagonal boron nitride.\nThis work provided a complete first-principles theoretical framework for defect\ndesign in 2D materials."
    },
    {
        "anchor": "Interplay of trapped species and absence of electron capture in\n  Moir\u00e9 heterobilayers: Moir\\'e heterobilayers host interlayer excitons in a natural, periodic array\nof trapping potentials. Recent work has elucidated the structure of the trapped\ninterlayer excitons and the nature of photoluminescence (PL) from trapped and\nitinerant charged complexes such as interlayer trions in these structures. In\nthis paper, our results serve to add to the understanding of the nature of PL\nemission and explain its characteristic blueshift with increasing carrier\ndensity, along with demonstrating a significant difference between the\ninterlayer exciton-trion conversion efficiency as compared to both localized\nand itinerant intra-layer species in conventional monolayers. Our results show\nthe absence of optical generation of trions in these materials, which we\nsuggest arises from the highly localized, near sub-nm confinement of trapped\nspecies in these Moir\\'e potentials.",
        "positive": "Intrinsic diamagnetism in the Weyl semimetal TaAs: We investigate the magnetic properties of TaAs, a prototype Weyl semimetal.\nTaAs crystals show weak diamagnetism with magnetic susceptibility of about -7 *\n10^{-7} emu/(g*Oe) at 5 K. A general feature is the appearance of a minimum at\naround 185 K in magnetization measurements as a function of temperature. No\nphase transition is observed in the temperature range between 5 K and 400 K.\nThe magnetic properties indicate that the intrinsic Fermi level in TaAs is not\nlocated at the Weyl nodes, in agreement with the theory prediction."
    },
    {
        "anchor": "Three-dimensional structure determination from a single view: The ability to determine the structure of matter in three dimensions has\nprofoundly advanced our understanding of nature. Traditionally, the most widely\nused schemes for 3D structure determination of an object are implemented by\nacquiring multiple measurements over various sample orientations, as in the\ncase of crystallography and tomography (1,2), or by scanning a series of thin\nsections through the sample, as in confocal microscopy (3). Here we present a\n3D imaging modality, termed ankylography (derived from the Greek words ankylos\nmeaning 'curved' and graphein meaning 'writing'), which enables complete 3D\nstructure determination from a single exposure using a monochromatic incident\nbeam. We demonstrate that when the diffraction pattern of a finite object is\nsampled at a sufficiently fine scale on the Ewald sphere, the 3D structure of\nthe object is determined by the 2D spherical pattern. We confirm the\ntheoretical analysis by performing 3D numerical reconstructions of a sodium\nsilicate glass structure at 2 Angstrom resolution and a single poliovirus at 2\n- 3 nm resolution from 2D spherical diffraction patterns alone. Using\ndiffraction data from a soft X-ray laser, we demonstrate that ankylography is\nexperimentally feasible by obtaining a 3D image of a test object from a single\n2D diffraction pattern. This approach of obtaining complete 3D structure\ninformation from a single view is anticipated to find broad applications in the\nphysical and life sciences. As X-ray free electron lasers (X-FEL) and other\ncoherent X-ray sources are under rapid development worldwide, ankylography\npotentially opens a door to determining the 3D structure of a biological\nspecimen in a single pulse and allowing for time-resolved 3D structure\ndetermination of disordered materials.",
        "positive": "First-principles calculations of the dispersion of surface phonons of\n  the unreconstructed and reconstructed Pt(110): We present result of calculations of the surface phonon dispersion curves for\nPt(110) using density functional theory in the local density approximation and\nnorm conserving pseudopotentials in a mixed-basis approach. Linear response\ntheory is invoked and both the unreconstructed, and the missing row (1x2)\nreconstructed surfaces are considered. We find that the reconstruction is not\ndriven by a phonon instability. Most of the observed phonon modes for the (1x2)\nstructure can be understood in terms of simple folding of the (1x1) Brillouin\nzone onto that for the (1x2) surface. Largest changes in the phonon frequencies\non surface reconstruction occur close to the zone boundary in the (001)\ndirection. Detailed comparison of atomic force constants for the (1x1) and the\n(1x2) surfaces and their bulk counterparts show that the bulk value is attained\nafter three layers. Our calculations reproduce nicely the Kohn anomaly observed\nalong the (110) direction in the bulk. We do not find a corresponding effect on\nthe surface."
    },
    {
        "anchor": "Spontaneous crystallization noise in mirrors of gravitational wave\n  detectors: Core optics components for high precision measurements are made of stable\nmaterials, having small optical and mechanical dissipation. The natural choice\nin many cases is glass, in particular fused silica. Glass is a solid amorphous\nstate of material that couldn't become a crystal due to high viscosity. However\nthermodynamically or externally activated stimulated local processes of\nspontaneous crystallization (known as devitrification) are still possible.\nBeing random, these processes can produce an additional noise, and influence\nthe performance of such experiments as laser gravitational wave detection.",
        "positive": "Networks of self-avoiding chains and Ogden-type constitutive equations\n  for elastomers: An expression is derived for the strain energy of a polymer chain under an\narbitrary three-dimensional deformation with finite strains. For a Gaussian\nchain, this expression is reduced to the conventional Moony--Rivlin\nconstitutive law, while for non-Gaussian chains it implies novel constitutive\nrelations. Based on the three-chain approximation, explicit formulas are\ndeveloped for the strain energy of a chain modeled as a self-avoiding random\nwalk. In the case of self-avoiding chains with stretched-exponential\ndistribution function of end-to-end vectors, the strain energy density of a\nnetwork is described by the Ogden law with only two material constants. For the\ndes Cloizeaux distribution function, the constitutive equation involves three\nadjustable parameters. The governing equations are verified by fitting\nobservations on uniaxial tension, uniaxial compression and biaxial tension of\nelastomers. Good agreement is demonstrated between the experimental data and\nthe results of numerical analysis. An analytical formula is derived for the\nratio of the Young's modulus of a self-avoiding chain to that of a Gaussian\nchain. It is found that the elastic modulus per chain in the Ogden network\nexceeds that in a Gaussian network by a factor of three, whereas the elastic\nmodulus of a chain with the generalized stretched exponential distribution\nfunction equals about half of the modulus of a Gaussian chain."
    },
    {
        "anchor": "Magnetic Effects in the Paraxial Regime of Elastic Electron Scattering: Based on a recent claim [Phys. Rev. Lett. 116, 127203 (2016)] that electron\nvortex can be used to image magnetism at the nanoscale in elastic scattering\nexperiments, using transmission electron microscopy, a comprehensive\ncomputational study is performed to study magnetic effects in the paraxial\nregime of elastic electron scattering in magnetic solids. Magnetic interactions\nfrom electron vortex beams, spin polarized electron beams and beams with phase\naberrations are considered, as they pass through ferromagnetic FePt or\nantiferromagnetic LaMnAsO. The magnetic signals are obtained by comparing the\nintensity over a disk in the diffraction plane for beams with opposite angular\nmomentum or aberrations. The strongest magnetic signals are obtained from\nvortex beams with large orbital angular momentum, where relative magnetic\nsignals above $10^{-3}$ are indicated for $10\\hbar$ orbital angular momentum,\nmeaning that relative signals of one percent could be expected with the even\nlarger orbital angular momenta, which have been produced in experimental\nsetups. All results indicate that beams with low acceleration voltage and small\nconvergence angles yield stronger magnetic signals, which is unfortunately\nproblematic for the possibility of high spatial resolution imaging.\nNevertheless, under atomic resolution conditions, relative magnetic signals in\nthe order of $10^{-4}$ are demonstrated, corresponding to an increase with one\norder of magnitude compared to previous work.",
        "positive": "Ultrahigh Elastically Compressible and Strain-Engineerable Intermetallic\n  Compounds Under Uniaxial Mechanical Loading: Intermetallic compounds possess unique atomic arrangements that often lead to\nexceptional material properties, but their extreme brittleness usually causes\nfracture at a limited strain of less than 1% and prevents their practical use.\nTherefore, it is critical for them to exhibit either plasticity or some form of\nstructural transition to absorb and release a sufficient amount of mechanical\nenergy before failure occurs. This study reports that the ThCr2Si2-structured\nintermetallic compound (CaFe2As2) and a hybrid of its structure (CaKFe4As4)\nwith 2 {\\mu}m in diameter and 6 {\\mu}m in height can exhibit superelasticity\nwith strain up to 17% through a reversible, deformation-induced, lattice\ncollapse, leading to a modulus of resilience orders of magnitude higher than\nthat of most engineering materials. Such superelasticity also can enable strain\nengineering, which refers to the modification of material properties through\nelastic strain. Density Functional Theory calculations and cryogenic\nnanomechanical tests predict that superconductivity in CaKFe4As4 could be\nturned on/off through the superelasticity process, before fracture occurs, even\nunder uniaxial compression, which is the favorable switching loading mode in\nmost engineering applications. Our results suggest that other members with the\nsame crystal structure (more than 2500 intermetallic compounds), and\nsubstitution series based on them should be examined for the possibility of\nmanifesting similar superelastic and strain-engineerable functional properties."
    },
    {
        "anchor": "Mode-coupling and polar nanoregions in the relaxor ferroelectric\n  Pb(Mg1/3Nb2/3)O3: We present a quantitative analysis of the phonon lineshapes obtained by\nneutron inelastic scattering methods in the relaxor ferroelectric\nPb(Mg1/3Nb2/3)O3 (PMN). Differences in the shapes and apparent positions of the\ntransverse acoustic (TA) and transverse optic (TO) phonon peaks measured in the\n(300) and (200) Brillouin zones at 690 K are well described by a simple model\nthat couples the TA and soft TO modes in which the primary parameter is the\nwave vector and temperature-dependent TO linewidth Gamma(q,T). This\nmode-coupling picture provides a natural explanation for the uniform\ndisplacements of the polar nanoregions, discovered by Hirota et al., as the PNR\nresult from the condensation of a soft TO mode that also contains a large\nacoustic component.",
        "positive": "ab initio informed inelastic neutron scattering for time-resolved local\n  dynamics in molten MgCl2: Ion dynamics that drive the transport and thermophysical properties of molten\nsalts are poorly understood due to challenges in precisely quantifying the\nspatial and temporal fluctuations of specific ions in highly disordered\nsystems. While the Van Hove correlation function (VHF) obtained from inelastic\nneutron scattering (INS) probes these dynamics directly, its interpretation is\nlimited by the inherent species-averaging of experiments, which obscures\nanalysis of key ion transport and solvation mechanisms. Here, ab initio\nmolecular dynamics (AIMD) is used to model the VHF, unravel its partial\ncontributions, and elucidate its underlying ionic transport mechanisms. Slow\ndecorrelation is revealed for oppositely charged ions (Mg2+ and Cl-) caused by\nion exchange across the solvation shell between adjoining ionocovalent\ncomplexes. Furthermore, transport coefficients are accurately recovered and\nconnections between macroscopic properties and ion dynamics are revealed. This\nstudy demonstrates the potential of ab initio-informed VHF to resolve\nlong-standing challenges in uncovering relationships between picosecond-scale\nion dynamics, mechanisms, and emergent physical properties of molten salts."
    },
    {
        "anchor": "A first-principles comparison of the electronic properties of\n  MgC_{y}Ni_{3} and ZnC_{y}Ni_{3} alloys: First-principles, density-functional-based electronic structure calculations\nare employed to study the changes in the electronic properties of ZnC_{y}Ni_{3}\nand MgC_{y}Ni_{3} using the Korringa-Kohn-Rostoker coherent-potential\napproximation method in the atomic sphere approximation (KKR-ASA CPA). As a\nfunction of decreasing C at%, we find a steady decrease in the lattice constant\nand bulk modulus in either alloys. However, the pressure derivative of the bulk\nmodulus displays an opposite trend. Following the Debye model, which relates\nthe pressure derivative of the bulk modulus with the average phonon frequency\nof the crystal, it can thus be argued that ZnCNi_{3} and its disordered alloys\nposses a different phonon spectra in comparison to its MgCNi_{3} counterparts.\nThis is further justified by the marked similarity we find in the electronic\nstructure properties such as the variation in the density of states and the\nHopfield parameters calculated for these alloys. The effects on the equation of\nstate parameters and the density of states at the Fermi energy, for partial\nreplacement of Mg by Zn are also discussed.",
        "positive": "Quantum rotational band model for the Heisenberg molecular magnet\n  Mo72Fe30: We derive the low temperature properties of the molecular magnet Mo72Fe30,\nwhere 30 Fe(3+) paramagnetic ions occupy the sites of an icosidodecahedron and\ninteract via isotropic nearest-neighbour antiferromagnetic Heisenberg exchange.\nThe key idea of our model (J.S. & M.L.) is that the low-lying excitations form\na sequence of rotational bands, i.e., for each such band the excitation\nenergies depend quadratically on the total spin quantum number. For\ntemperatures below 50 mK we predict that the magnetisation is described by a\nstaircase with 75 equidistant steps as the magnetic field is increased up to a\ncritical value and saturated for higher fields. For higher temperatures thermal\nbroadening effects wash out the staircase and yield a linear ramp below the\ncritical field, and this has been confirmed by our measurements (R.M.). We\ndemonstrate that the lowest two rotational bands are separated by an energy gap\nof 0.7 meV, and this could be tested by EPR and inelastic neutron scattering\nmeasurements. We also predict the occurrence of resonances at temperatures\nbelow 0.1 K in the proton NMR spin-lattice relaxation rate associated with\nlevel crossings. As rotational bands characterize the spectra of many magnetic\nmolecules our method opens a new road towards a description of their\nlow-temperature behaviour which is not otherwise accessible."
    },
    {
        "anchor": "The problem of a perfect lens made of a slab with negative refraction: The problem of the principal existence of the perfect lens and superlensing\nis discussed. We have demonstrated that in the case of the virtual focus the\nidea of perfect lens based upon amplification of evanescent waves as proposed\nby Pendry is perfectly right unlike the case of the real foci. We think that\nsome experimental results claiming superlensing can be explained in terms of\nthe proposed theory for the case when the virtual focus is inside the lens but\nvery close to the rear face of it.",
        "positive": "Magnetic properties of multi-domain epitaxial EuPd$_2$ thin films: Europium intermetallic compounds show a variety of different ground states\nand anomalous physical properties due to the interactions between the localized\n4f electrons and the delocalized electronic states. Europium is also the most\nreactive of the rare earth metals which might be the reason why very few works\nare concerned with the properties of Eu-based thin films. Here we address the\nlow-temperature magnetic properties of ferromagnetic EuPd$_2$ thin films\nprepared by molecular beam epitaxy. The epitaxial (111)-oriented thin films\ngrow on MgO (100) with eight different domain orientations. We analyze the\nlow-temperature magnetic hysteresis behavior by means of micromagnetic\nsimulations taking the multi-domain morphology explicitly into account and\nquantify the magnetic crystal anisotropy contribution. By ab initio\ncalculations we trace back the microscopic origin of the magnetic anisotropy to\nthin film-induced biaxial strain."
    },
    {
        "anchor": "Triggering one dimensional phase transition with defects at the graphene\n  zigzag edge: One well-known argument about one dimensional(1D) system is that 1D phase\ntransition at finite temperature cannot exist, despite this concept depends on\nconditions such as range of interaction, external fields and periodicity.\nTherefore 1D systems usually have random fluctuations with intrinsic domain\nwalls arising which naturally bring disorder during transition. Herein we\nintroduce a real 1D system in which artificially created defects can induce a\nwell-defined 1D phase transition. The dynamics of structural reconstructions at\ngraphene zigzag edges are examined by in situ aberration corrected transmission\nelectron microscopy (ACTEM). Combined with an in-depth analysis by ab-initio\nsimulations and quantum chemical molecular dynamics (QM/MD), the complete\ndefect induced 1D phase transition dynamics at graphene zigzag edge is clearly\ndemonstrated and understood on the atomic scale. Further, following this phase\ntransition scheme, graphene nanoribbons (GNR) with different edge symmetries\ncan be fabricated, and according to our electronic structure and quantum\ntransport calculations, a metal-insulator-semiconductor transition for\nultrathin GNRs is proposed.",
        "positive": "Photoemission orbital tomography for excitons in organic molecules: Driven by recent developments in time-resolved photoemission spectroscopy, we\nextend the successful method of photoemission orbital tomography (POT) to\nexcitons. Our theory retains the intuitive orbital picture of POT, while\nrespecting both the entangled character of the exciton wave function and the\nenergy conservation in the photoemission process. Analyzing results from three\norganic molecules, we classify generic exciton structures and give a simple\ninterpretation in terms of natural transition orbitals. We validate our\nfindings by directly simulating pump-probe experiments with time-dependent\ndensity functional theory."
    },
    {
        "anchor": "Calculation of the substitutional fraction of ion-implanted He in an Fe\n  target: Ion-implantation is a useful technique to study irradiation damage in nuclear\nmaterials. To study He effects in nuclear fusion conditions, He is co-implanted\nwith damage ions to reproduce the correct He/dpa ratios in the desired or\navailable depth range. However, the short-term fate of these He ions, i.e over\nthe time scales of their own collisional phase, has not been yet unequivocally\nestablished. Here we present an atomistic study of the short-term evolution of\nHe implantation in an Fe substrate to approximate the conditions encountered in\ndual ion-implantation studies in ferritic materials. Specifically, we calculate\nthe fraction of He atoms that end up in substitutional sites shortly after\nimplantation, i.e. before they contribute to long-term miscrostructural\nevolution. We find that fractions of at most 3% should be expected for most\nimplantation studies. In addition, we carry out an exhaustive calculation of\ninterstitial He migration energy barriers in the vicinity of matrix vacancies\nand find that they vary from approximately 20 to 60 meV depending on the\nseparation and orientation of the He-vacancy pair.",
        "positive": "Finite-temperature ductility-brittleness and electronic structures of\n  Al$_{n}$Sc (n=1, 2 and 3): Finite-temperature ductility-brittleness and electronic structures of\nAl$_3$Sc, Al$_2$Sc and AlSc are studied comparatively by first-principles\ncalculations and ab-initio molecular dynamics. Results show that Al$_3$Sc and\nAl$_2$Sc are inherently brittle at both ground state and finite temperatures.\nBy contrast, AlSc possesses a significantly superior ductility evaluated from\nall Pugh's, Pettifor's and Poisson's ductility-brittleness criteria. At ground\nstate, AlSc meets the criteria of ductile according to Pugh's and Poisson's\ntheories, while it is categorized as the brittle in the frame of Pettifor's\npicture. With the increasing temperature, the ductility of all the studied\ncompounds exhibits a noticeable improvement. In particular, as the temperature\nrises, the Cauchy pressure of AlSc undergoes a transition from negative to\npositive. Thus, at high temperatures (T > 600 K), AlSc is unequivocally\nclassified as the ductile from all criteria considered. In all Al$_3$Sc,\nAl$_2$Sc and AlSc, the Al-Al bond, originated from s-p and p-p orbital\nhybridizations, and the Al-Sc bond, dominated by p-d covalent hybridization,\nare the first and second strongest chemical bonds, respectively. To explain the\ndifference in mechanical properties of the studied compounds, the mean bond\nstrength (MBS) is evaluated. The weaker Al-Al bond in AlSc, leading to a\nsmaller MBS, could be the origin for the softer elastic stiffness and superior\nintrinsic ductility. The longer length of the Al-Al bond in AlSc is responsible\nfor its weaker bond strength. Furthermore, the enhanced metallicity of the\nAl-Al bond in AlSc would also contribute to its exceptional ductility."
    },
    {
        "anchor": "Phonon-induced geometric chirality: Chiral phonons conventionally describe circularly polarized lattice\nvibrations that carry angular momentum and that represent a case of dynamic\nchirality. Here, we demonstrate that linearly polarized phonons can also induce\ngeometric chirality in achiral crystals when excited nonlinearly with an\nultrashort laser pulse. We show that nonlinear phonon coupling can be used to\nquasistatically displace the crystal structure along the eigenvectors of phonon\nmodes that reduce the symmetry of the lattice to that of the enantiomorphic\npoint groups characterizing chiral crystals. The structure can be switched\nbetween the two enantiomers by reorienting the polarization of the laser pulse.\nThese linearly polarized chiral phonons enable the creation of chiral crystal\ngeometries on demand and offer a novel pathway towards engineering chiral\nelectronic states and optical properties.",
        "positive": "Band-filling-controlled magnetism from transition metal intercalation in\n  $N_{1/3}$NbS$_2$ revealed with first-principles calculations: We present a first-principles study of the effect of 3$d$ transition metal\nintercalation on the magnetic properties of the 2H-NbS$_2$ system, using\nspin-resolved density functional theory calculations to investigate the\nelectronic structure of $N_{1/3}$NbS$_2$ ($N$ = Ti, V, Cr, Mn, Fe, Co, Ni).\n  We are able to accurately determine the magnetic moments and crystal field\nsplitting, and find that the magnetic properties of the materials are\ndetermined by a mechanism based on filling rigid bands with electrons from the\nintercalant.\n  We predict the dominant magnetic interaction of these materials by\nconsidering Fermi surface nesting, finding agreement with experiment where data\nare available."
    },
    {
        "anchor": "Configurational entropy of network-forming materials: We present a computationally efficient method to calculate the\nconfigurational entropy of network-forming materials. The method requires only\nthe atomic coordinates and bonds of a single well-relaxed configuration. This\nis in contrast to the multiple simulations that are required for other methods\nto determine entropy, such as thermodynamic integration. We use our method to\nobtain the configurational entropy of well-relaxed networks of amorphous\nsilicon and vitreous silica. For these materials we find configurational\nentropies of 1.02 kb and 0.97 kb per silicon atom, respectively, with kb the\nBoltzmann constant.",
        "positive": "Impact of intrinsic localized modes of atomic motion on materials\n  properties: Recent neutron and x-ray scattering measurements show intrinsic localized\nmodes (ILMs) in metallic uranium and ionic sodium iodide. Here, the role ILMs\nplay in the behavior of these materials is examined. With the thermal\nactivation of ILMs, thermal expansion is enhanced, made more anisotropic, and,\nat a microscopic level, becomes inhomogeneous. Interstitial diffusion, ionic\nconductivity, the annealing rate of radiation damage, and void growth are all\ninfluenced by ILMs. The lattice thermal conductivity is suppressed above the\nILM activation temperature while no impact is observed in the electrical\nconductivity. This complement of transport properties suggests that ILMs could\nimprove thermoelectric performance. Ramifications also include thermal\nratcheting, a transition from brittle to ductile fracture, and possibly a phase\ntransformation in uranium."
    },
    {
        "anchor": "Anomalous Hall effect in the noncollinear antiferromagnet Mn5Si3: Metallic antiferromagnets with noncollinear orientation of magnetic moments\nprovide a playground for investigating spin-dependent transport properties by\nanalysis of the anomalous Hall effect. The intermetallic compound Mn5Si3 is an\nintinerant antiferromagnet with collinear and noncollinear magnetic structures\ndue to Mn atoms on two inequivalent lattice sites. Here, magnetotransport\nmeasurements on polycrystalline thin films and a single crystal are reported.\nIn all samples, an additional contribution to the anomalous Hall effect\nattributed to the noncollinear arrangment of magnetic moments is observed.\nFurthermore, an additional magnetic phase between the noncollinear and\ncollinear regimes above a metamagnetic transition is resolved in the single\ncrystal by the anomalous Hall effect.",
        "positive": "Adiabatic spin dynamics and effective exchange interactions from\n  constrained tight-binding electronic structure theory: Beyond the Heisenberg\n  regime: We consider an implementation of the adiabatic spin dynamics approach in a\ntight-binding description of the electronic structure. The adiabatic\napproximation for spin-degrees of freedom assumes that the faster electronic\ndegrees of freedom are always in a quasi-equilibrium state, which significantly\nreduces the numerical complexity in comparison to the full electron dynamics.\nNon-collinear magnetic configurations are stabilized by a constraining field,\nwhich allows to directly obtain the effective magnetic field from the negative\nof the constraining field. While the dynamics are shown to conserve energy, we\ndemonstrate that adiabatic spin dynamics does not conserve the total spin\nangular momentum when the lengths of the magnetic moments are allowed to\nchange, which is confirmed by numerical simulations. Furthermore, we develop a\nmethod to extract an effective two-spin exchange interaction from the energy\ncurvature tensor of non-collinear states, which we calculate at each time step\nof the numerical simulations. We demonstrate the effect of non-collinearity on\nthis effective exchange and limitations due to multi-spin interactions in\nstrongly non-collinear configurations beyond the regime where the Heisenberg\nmodel is valid. The relevance of the results are discussed with respect to\nexperimental pump-probe experiments that follow the ultra-fast dynamics of\nmagnetism."
    },
    {
        "anchor": "Boron-doped diamond: Boron-doped diamond undergoes an insulator-metal transition at some critical\nvalue (around 2.21 at %) of the dopand concentration. Here, we report a simple\nmethod for the calculation of its bulk modulus, based on the thermodynamical\nmodel, by Varotsos and Alexopoulos, that has been originally suggested for the\ninterconnection between the defect formation parameters in solids and bulk\nproperties. The results obtained at the doping level of 2.6 at %, which was\nlater improved at the level 0.5 at %, are in agreement with the experimental\nvalues.",
        "positive": "Structural and electronic properties of epitaxially-strained LaVO_3 from\n  density functional theory and dynamical mean-field theory: The effect of epitaxial strain on the structural and electronic properties of\nLaVO_3 is investigated through density functional theory (DFT) and dynamical\nmean field theory (DMFT). Two different growth orientations of the crystal are\nconsidered, one preserving the bulk Pbnm space-group symmetry and another\ngiving rise to a symmetry lowering to P2_1/m. In the nonmagnetic DFT\nstructures, the two growth orientations are equally favored for all tensile\nstrains considered here, as well as for compressive strains weaker than -3%.\nFor stronger compressive strains, the P2_1/m orientation is favored and shows a\ncomplete suppression of octahedral tilts along the out-of-plane direction.\nMagnetically-ordered structures do not show a complete tilt suppression, but\nthe trend points to a similar reduction of the out-of-plane V-O-V bond angles\nunder compressive strain. Our DMFT calculations show that, in accord with\nroom-temperature experiments, the bulk paramagnetic Mott-insulating state of\nLaVO_3 is robust against epitaxial strains attainable in thin films, since the\nsuppression of orbital fluctuations counteracts the effect of bandwidth\nincrease with compressive strain. Under stronger compressive strains, the\nstraightening of the V-O-V bonds in the P2_1/m geometry interferes with the\nsuppression of orbital fluctuations and hence perturbs the Mott phase more\nstrongly, albeit not enough to achieve a metallic phase."
    },
    {
        "anchor": "Role of the intrinsic surface state in the decay of image states at a\n  metal surface: The role of the intrinsic surface state ($n=0$) in the decay of the first\nimage state ($n=1$) at the (111) surface of copper is investigated. Inelastic\nlinewidths are evaluated from the knowledge of the imaginary part of the\nelectron self-energy, which we compute, within the GW approximation of\nmany-body theory, by going beyond a free-electron description of the metal\nsurface. Single-particle wave functions are obtained by solving the\nSchr\\\"odinger equation with a realistic one-dimensional model potential, and\ndeparture of the motion along the surface from free-electron behaviour is\nconsidered through the introduction of the effective mass. The decay of the\nfirst image state of Cu(111) into the intrinsic surface state is found to\nresult in a linewidth that represents a 40% of the total linewidth. The\ndependence of linewidths on the momentum of the image state parallel to the\nsurface is also investigated.",
        "positive": "Abnormal improved dielectric in La doped relaxor ferroelectric PNN-PHT: Relaxor ferroelectrics are complex materials with distinct properties\ndifferent from classic ferroelectrics. Probing frequency depended dielectric\nsusceptibility is its trait. Other empirical laws build on classic\nferroelectrics are still applicable to relaxor ferroelectrics. Here we report\nan abnormal improved dielectric in La doped relaxor ferroelectric\n0.4PNN-0.6PHT, which deviated from the consistent variation relationship with\npiezoelectric coefficient. A mesoscale mechanism is proposed to reveal the\norigin of the improved dielectric response in 0.4PNN-0.6PHT, where the polar\nnanoregions alignment can facilitate polarization response to external field.\nThis mechanism emphasizes the critical role of polarization fluctuation on the\nmacroscopic properties of 0.4PNN-0.6PHT."
    },
    {
        "anchor": "Mg/Ti multilayers: structural, optical and hydrogen absorption\n  properties: Mg-Ti alloys have uncommon optical and hydrogen absorbing properties,\noriginating from a \"spinodal-like\" microstructure with a small degree of\nchemical short-range order in the atoms distribution. In the present study we\nartificially engineer short-range order by depositing Pd-capped Mg/Ti\nmultilayers with different periodicities and characterize them both\nstructurally and optically. Notwithstanding the large lattice parameter\nmismatch between Mg and Ti, the as-deposited metallic multilayers show good\nstructural coherence. Upon exposure to H2 gas a two-step hydrogenation process\noccurs, with the Ti layers forming the hydride before Mg. From in-situ\nmeasurements of the bilayer thickness L at different hydrogen pressures, we\nobserve large out-of-plane expansions of the Mg and Ti layers upon\nhydrogenation, indicating strong plastic deformations in the films and a\nconsequent shortening of the coherence length. Upon unloading at room\ntemperature in air, hydrogen atoms remain trapped in the Ti layers due to\nkinetic constraints. Such loading/unloading sequence can be explained in terms\nof the different thermodynamic properties of hydrogen in Mg and Ti, as shown by\ndiffusion calculations on a model multilayered systems. Absorption isotherms\nmeasured by hydrogenography can be interpreted as a result of the elastic\nclamping arising from strongly bonded Mg/Pd and broken Mg/Ti interfaces.",
        "positive": "Oxygen Partial Pressure during Pulsed Laser Deposition: Deterministic\n  Role on Thermodynamic Stability of Atomic Termination Sequence at\n  SrRuO3/BaTiO3 Interface: With recent trends on miniaturizing oxide-based devices, the need for\natomic-scale control of surface/interface structures by pulsed laser deposition\n(PLD) has increased. In particular, realizing uniform atomic termination at the\nsurface/interface is highly desirable. However, a lack of understanding on the\nsurface formation mechanism in PLD has limited a deliberate control of\nsurface/interface atomic stacking sequences. Here, taking the prototypical\nSrRuO3/BaTiO3/SrRuO3 (SRO/BTO/SRO) heterostructure as a model system, we\ninvestigated the formation of different interfacial termination sequences\n(BaO-RuO2 or TiO2-SrO) with oxygen partial pressure (PO2) during PLD. We found\nthat a uniform SrO-TiO2 termination sequence at the SRO/BTO interface can be\nachieved by lowering the PO2 to 5 mTorr, regardless of the total background gas\npressure (Ptotal), growth mode, or growth rate. Our results indicate that the\nthermodynamic stability of the BTO surface at the low-energy kinetics stage of\nPLD can play an important role in surface/interface termination formation. This\nwork paves the way for realizing termination engineering in functional oxide\nheterostructures."
    },
    {
        "anchor": "Phase field model for coupled displacive and diffusive microstructural\n  processes under thermal loading: A non-isothermal phase field model that captures both displacive and\ndiffusive phase transformations in a unified framework is presented. The model\nis developed in a formal thermodynamic setting, which provides guidance on\nadmissible constitutive relationships and on the coupling of the numerous\nphysical processes that are active. Phase changes are driven by\ntemperature-dependent free-energy functions that become non-convex below a\ntransition temperature. Higher-order spatial gradients are present in the model\nto account for phase boundary energy, and these terms necessitate the\nintroduction of non-standard terms in the energy balance equation in order to\nsatisfy the classical entropy inequality point-wise. To solve the resulting\nbalance equations, a Galerkin finite element scheme is elaborated. To deal\nrigorously with the presence of high-order spatial derivatives associated with\nsurface energies at phase boundaries in both the momentum and mass balance\nequations, some novel numerical approaches are used. Numerical examples are\npresented that consider boundary cooling of a domain at different rates, and\nthese results demonstrate that the model can qualitatively reproduce the\nevolution of microstructural features that are observed in some alloys,\nespecially steels. The proposed model opens a number of interesting\npossibilities for simulating and controlling microstructure pattern development\nunder combinations of thermal and mechanical loading.",
        "positive": "Impact of Cr doping on the structure, optical and magnetic properties of\n  nanocrystalline ZnO particles: The role of Cr incorporation into the ZnO were probed through investigations\ninto the structural, optical and magnetic properties. Zn1-xCrxO with x = 0,\n0.01, 0.03 and 0.05, nanoparticles were prepared by solution combustion method.\nPowder x-ray diffraction (XRD) results reveal, all the synthesized samples are\nin single hexagonal wurtzite crystal structures, indicating that Cr3+ ions\nsubstitute the Zn2+ ions without altering the structure. The crystallite size\nand microstrain were calculated using the Willamson-Hall method and found to be\n36 +- 2 nm for ZnO and it reduced with the increase of Cr dopant concentration\nto 20 +- 2 nm for Zn0.95Cr0.05O. Transmission electron microscopy (TEM)\nrevealed that the particle size were 48 +- 2 nm, 29 +- 2 nm and 25 +- 2 nm for\nthe Zn1-xCrxO with x = 0, 0.03 and 0.05, respectively. TEM morphology indicated\nparticles are agglomerated in the doped samples. The band-gap decreases\nslightly from 3.305 +- 0.003 eV to 3.292 +- 0.003 eV with increase of Cr\ncontent from x = 0 to 0.05, respectively. Photoluminescence measurements\nrevealed the presence of defects in the samples, associated with zinc vacancies\nand singly ionized oxygen vacancy. The field-dependent magnetization\nmeasurements of ZnO and Cr-doped ZnO were carried out using a vibrating sample\nmagnetometer (VSM) at 300 K. All the samples exhibits ferromagnetic behavior.\nThis long-range ferromagnetism ordering observed in ZnO is explained based on\nbound magnetic polaron (BMP) mechanism. The singly ionized oxygen vacancies\nplaying a crucial role in observed room temperature ferromagnetism (RTFM) in\nZnO. There is a sufficient amount of BMPs formed in Cr doped ZnO because of the\ndefects present in these samples. Therefore, the overlapping of BMPs results in\nthe RTFM. However, the antiferromagnetic coupling at a higher doping\nconcentration of Cr, weakens the observed RTFM."
    },
    {
        "anchor": "Unraveling the \"Green Gap\" problem: The role of random alloy\n  fluctuations in InGaN/GaN light emitting diodes: White light emitting diodes based on III-nitride InGaN/GaN quantum wells\ncurrently offer the highest overall efficiency for solid state lighting\napplications. Although current phosphor-converted white LEDs have high\nelectricity-to-light conversion efficiencies, it has been recently pointed out\nthat the full potential of solid state lighting could be exploited only by\ncolor mixing approaches without employing phosphor-based wavelength conversion.\nSuch an approach requires direct emitting LEDs of different colors, in\nparticular in the green/yellow range ov the visible spectrum. This range,\nhowever, suffers from a systematic drop in efficiency, known as the \"green\ngap\", whose physical origin has not been understood completely so far. In this\nwork we show by atomistic simulations that a consistent part of the \"green gap\"\nin c-plane InGaN/GaN based light emitting diodes may be attributed to a\ndecrease in the radiative recombination coefficient with increasing Indium\ncontent due to random fluctuations of the Indium concentration naturally\npresent in any InGaN alloy.",
        "positive": "Ferroelectric phases and phase transitions in CsGeBr$_3$ induced by\n  mechanical load: First-principles-based atomistic simulations are used to reveal ferroelectric\nphases and phase transitions induced in a semiconductor ferroelectric,\nCsGeBr$_3$, by external loads: hydrostatic pressure, uniaxial and biaxial\nstresses, and misfit strain. Hydrostatic pressure was found to suppress the\nCurie point at the rate -0.45$T_C(0)$ K/GPa, where $T_C(0)$ is the zero\npressure Curie temperature. Stresses and misfit strains were found to induce\nadditional ferroelectric phase transitions and phases not available under\nnormal conditions. We find that tensile load significantly enhances both the\nCurie temperature and spontaneous polarization, while compressive load has the\nopposite effect but with the difference that the Curie temperature is only\nslightly suppressed. The isothermal dependencies of polarization on pressure\nand stresses are highly nonlinear, which could result in large nonlinear\npiezoelectric responses. The phase diagrams reveal the diversity of the phases\naccessible through mechanical load, which include tetragonal, orthorhombic and\nmonoclinic symmetries in addition to the rhombohedral and cubic ones realizable\nunder normal conditions. We believe that this work reveals the potential of\nGe-based halide perovskites for applications in energy converting devices,\nwhich is especially significant in the current pursuit of environmental\nfriendly lead-free technologies."
    },
    {
        "anchor": "Magnetotransport properties and giant anomalous Hall angle in\n  half-Heusler compound TbPtBi: Magnetic lanthanide half-Heuslers ($R$PtBi; $R$ being the lanthanide)\nrepresent an attractive subgroup of the Heusler family and have been identified\nas ideal candidates for time reversal symmetry breaking topological Weyl\nsemimetals. In this paper, we present the detailed analysis of the\nmagnetotransport properties of frustrated antiferromagnet TbPtBi. This material\nshows large, non-saturating magnetoresistance (MR) with unusual magnetic field\ndependence. The MR of TbPtBi is significantly anisotropic with respect to the\nmagnetic field, applied along different crystallographic directions and\nindicates the anisotropic nature of the Fermi surface. The chiral anomaly\ninduced negative longitudinal magnetoresistance confirms the presence of Weyl\nfermions. At low temperature, Berry phase driven large anomalous Hall\nconductivity has been observed. The calculated anomalous Hall angle is the\nlargest reported so far.",
        "positive": "Symmetric Helmholtz Fermi-surface harmonics for an optimal\n  representation of anisotropic quantities on the Fermi surface: Application to\n  the electron-phonon problem: We outline a numerical procedure to incorporate the crystal symmetries in the\nHelmholtz Fermi-surface harmonics basis set, which are the solutions of the\nHelmholtz equation defined on the Fermi surface. This improvement allows for an\noptimal representation of anisotropic quantities defined on the Fermi surface\nin terms of few symmetric elements of the set. We demonstrate the general\nvalidity of our approach by identifying the fully symmetric Helmholtz\nFermi-surface harmonics subset for several representative systems with\ndifferent crystal structures, namely, FCC-Cu, HEX-MgB$_2$, and BCC-YH$_6$.\nFurthermore, we illustrate the potential of the method applied to the\nelectron-phonon problem, showing that the anisotropic electron-phonon\nmass-enhancement parameter $\\lambda_{\\bf k}$ can be represented to high\naccuracy by a handful of coefficients. This works as an effective filter,\npaving the way for a reduction of several orders of magnitude in the\ncomputation of superconductivity, impurity problems, or any other Fermi surface\ndependent property of metals from first principles."
    },
    {
        "anchor": "Pulsed Laser Deposition of a PBN:65 Morphotropic Phase Boundary Thin\n  Film with Large Electrostriction: We deposited epitaxial thin films of Morphotropic Phase Boundary (MPB)\n  Pb0.65Ba0.35Nb2O6 (PBN:65) on MgO substrates using pulsed laser deposition.\nAfterwards, a novel transmission optical experiment was developed to measure\nthe electric field-induced bending angle of the thin film sample using a\ndivergent incident light. From which the electric field-induced strain was\nobtained, and it was used to calculate the electrostrictive constant of the PBN\nthin film. The result is 0.000875 um2/V2, and it is consistent with what we\nmeasured in the reflection experiment.",
        "positive": "Large voltage tuning of Dzyaloshinskii-Moriya Interaction: a route\n  towards dynamic control of skyrmion chirality: Electric control of magnetism is a prerequisite for efficient and low power\nspintronic devices. More specifically, in heavy metal/ ferromagnet/ insulator\nheterostructures, voltage gating has been shown to locally and dynamically tune\nmagnetic properties like interface anisotropy and saturation magnetization.\nHowever, its effect on interfacial Dzyaloshinskii-Moriya Interaction (DMI),\nwhich is crucial for the stability of magnetic skyrmions, has been challenging\nto achieve and has not been reported yet for ultrathin films. Here, we\ndemonstrate 130% variation of DMI with electric field in Ta/FeCoB/TaOx\ntrilayers through Brillouin Light Spectroscopy (BLS). Using polar-\nMagneto-Optical-Kerr-Effect microscopy, we further show a monotonic variation\nof DMI and skyrmionic bubble size with electric field, with an unprecedented\nefficiency. We anticipate through our observations that a sign reversal of DMI\nwith electric field is possible, leading to a chirality switch. This dynamic\nmanipulation of DMI establishes an additional degree of control to engineer\nprogrammable skyrmion based memory or logic devices."
    },
    {
        "anchor": "Symmetry-Protected Topological Triangular Weyl Complex: Weyl points are often believed to appear in pairs with opposite chirality. In\nthis work, we show by first-principles calculations and symmetry analysis that\nsingle Weyl phonons with linear dispersion and double Weyl phonons with\nquadratic dispersion are simultaneously present between two specific phonon\nbranches in realistic materials with trigonal or hexagonal lattices. These\nphonon Weyl points are guaranteed to locate at high-symmetry points due to the\nscrew rotational symmetry, forming a unique triangular Weyl complex. In sharp\ncontrast to conventional Weyl systems with surface arcs terminated at the\nprojections of a pair of Weyl points with opposite chirality, the phonon\nsurface arcs of the unconventional triangular Weyl complex connect the\nprojections of one double Weyl point and two single Weyl points. Importantly,\nthe phonon surface arcs originating from the triangular Weyl complex are\nextremely long and span the entire surface Brillouin-zone. Furthermore, there\nare only nontrivial phonon surface states across the iso-frequency surface,\nwhich facilitates their detection in experiments and further applications. Our\nwork not only offers the promising triangular phonon Weyl complex but also\nprovides guidance for exploring triangular Weyl bosons in both phononic and\nphotonic systems.",
        "positive": "Tuning Conductivity and Spin Dynamics in Few-Layer Graphene via In Situ\n  Potassium Exposure: Chemical modification, such as intercalation or doping of novel materials is\nof great importance for exploratory material science and applications in\nvarious fields of physics and chemistry. In the present work, we report the\nsystematic intercalation of chemically exfoliated few-layer graphene with\npotassium while monitoring the sample resistance using microwave conductivity.\nWe find that the conductivity of the samples increases by about an order of\nmagnitude upon potassium exposure. The increased of number of charge carriers\ndeduced from the ESR intensity also reflects this increment. The doped phases\nexhibit two asymmetric Dysonian lines in ESR, a usual sign of the presence of\nmobile charge carriers. The width of the broader component increases with the\ndoping steps, however, the narrow components seem to have a constant line\nwidth."
    },
    {
        "anchor": "Robust half-metallic ferromagnetism in the zincblende CrSb: Using the accurate first-principle method within density-functional theory,\nwe systematically study CrSb in the zincblende (zb) structure. The zb CrSb is\npredicted of robust half-metallic ferromagnetism (HMFM) with a magnetic moment\nof 3.000 $\\mu_B$ per formula. It is much better than other zb compounds with\nHMFM because its spin-flip gap reaches 0.774 eV at the equilibrium volume and\npersists nonzero with its volume changing theoretically from -21% to +60%. It\nis found there may be a common mechanism for the HMFM in all the zb Cr- and\nMn-pnictides. Since being compatible with the III-V semiconductors, this\nexcellent HMFM of the zb CrSb should be useful in spin electronics and other\napplications.",
        "positive": "Making sense of nanocrystal lattice fringes: The orientation-dependence of thin-crystal lattice fringes can be gracefully\nquantified using fringe-visibility maps, a direct-space analog of Kikuchi maps.\nAs in navigation of reciprocal space with the aid of Kikuchi lines,\nfringe-visibility maps facilitate acquisition of 3D crystallographic\ninformation in lattice images. In particular, these maps can help researchers\nto determine the 3D lattice parameters of individual nano-crystals, to ``fringe\nfingerprint'' collections of randomly-oriented particles, and to measure local\nspecimen-thickness with only modest tilt. Since the number of fringes in an\nimage increases with maximum spatial-frequency squared, these strategies (with\nhelp from more precise goniometers) will be more useful as\naberration-correction moves resolutions into the subangstrom range."
    },
    {
        "anchor": "Helicity-tunable spin Hall and spin Nernst effects in unconventional\n  chiral fermion semimetals XY (X=Co, Rh; Y=Si, Ge): Transition metal monosilicides CoSi, CoGe, RhSi and RhGe in the chiral cubic\nB20 structure have recently been found to host unconventional chiral fermions\nbeyond spin-1/2 WFs, and also exhibit exotic physical phenomena such as long\nFermi arc surface states, GME and quantized CPGE. Thus, exploring novel\nspin-related transports in these unconventional chiral fermion semimetals may\nopen a new door for spintronics and spin caloritronics. In this paper, we study\nthe intrinsic SHE and SNE in the CoSi family based on ab initio relativistic\nband structure calculations. First, we find that unlike nonchiral cubic metals,\nthe CoSi family have two independent nonzero SHC (SNC) tensor elements, namely,\n$\\sigma_{xy}^z$ and $\\sigma_{xz}^y$ ($\\alpha_{xy}^z$ and $\\alpha_{xz}^y$)\ninstead of one element. Furthermore, the SHC ($\\sigma_{xy}^z$ and\n$\\sigma_{xz}^y$) and helicity of the chiral structure are found to be\ncorrelated, thus enabling SHE detection of structural helicity and also chiral\nfermion chirality. Second, the intrinsic SHE and SNE in some of the CoSi family\nare large. In particular, the calculated SHC of RhGe is as large as -140\n($\\hbar$/e)(S/cm). The calculated SNC of CoGe is also large, being -1.3\n($\\hbar$/e)(A/m K) at room temperature. Due to their semimetallic nature with\nlow electrical conductivity, these topological semimetals may have large spin\nHall and spin Nernst angles, being comparable to that of Pt metal. The SHC and\nSNC of these compounds can also be increased by raising or lowering $\\mu$ to,\ne.g., the topological nodes, via either chemical doping or electrical gating.\nOur findings thus indicate that the CoSi family not only would provide a\nmaterial platform for exploring novel spin-transports and exotic phenomena in\nunconventional chiral fermion semimetals but also could be promising materials\nfor developing better spintronic and spin caloritronic devices.",
        "positive": "Method for Computing Short-Range Forces between Solid-Liquid Interfaces\n  Driving Grain Boundary Premelting: We present a molecular dynamics based method for computing accurately\nshort-range structural forces resulting from the overlap of spatially diffuse\nsolid-liquid interfaces at wetted grain boundaries close to the melting point.\nThe method is based on monitoring the fluctuations of the liquid layer width at\ndifferent temperatures to extract the excess interfacial free-energy as a\nfunction of this width. The method is illustrated for a high energy Sigma 9\ntwist boundary in pure Ni. The short-range repulsion driving premelting is\nfound to be dominant in comparison to long-range dispersion and entropic forces\nand consistent with previous experimental findings that nanometer-scale layer\nwidths may only be observed very close to the melting point."
    },
    {
        "anchor": "Magnetic interactions and spin excitations in van der Waals ferromagnet\n  VI$_3$: Using a combination of density functional theory (DFT) and spin-wave theory\nmethods, we investigate the magnetic interactions and spin excitations in\nsemiconducting VI$_3$. Exchange parameters of monolayer, bilayer, and bulk\nforms are evaluated by mapping the magnetic energies of various spin\nconfigurations, calculated using DFT+$U$, onto the Heisenberg model. The\nintralayer couplings remain largely unchanged in three forms of VI$_3$, while\nthe interlayer couplings show stronger dependence on the dimensionality of the\nmaterials. We calculate the spin-wave spectra within a linear spin-wave theory\nand discuss how various exchange parameters affect the magnon bands. The\nmagnon-magnon interaction is further incorporated, and the Curie temperature is\nestimated using a self-consistently renormalized spin-wave theory. To\nunderstand the roles of constituent atoms on magnetocrystalline anisotropy\nenergy (MAE), we resolve MAE into sublattices and find that a strong negative\nV-I inter-sublattice contribution is responsible for the relatively small\neasy-axis MAE in VI$_3$.",
        "positive": "Pressure-induced inverse order-disorder transition in double perovskites: Given the consensus that pressure improves cation order in most of known\nmaterials, a discovery of pressure-induced disorder could require\nreconsideration of order-disorder transition in solid state physics/chemistry\nand geophysics. Double perovskites Y2CoIrO6 and Y2CoRuO6 synthesized at ambient\npressure show B-site order, while the polymorphs synthesized at 6 and 15 GPa\nare partially-ordered and disordered respectively. With the decrease of\nordering degrees, the lattices are shrunken and the crystal structures alter\nfrom monoclinic to orthorhombic symmetry. Correspondingly, long-range\nferrimagnetic order in the B-site ordered phases are gradually overwhelmed by\nB-site disorder. Theoretical calculations suggest that unusual unit cell\ncompressions under external pressures unexpectedly stabilize the disordered\nphases of Y2CoIrO6 and Y2CoRuO6."
    },
    {
        "anchor": "Machine Learning approach to muon spectroscopy analysis: In recent years, Artificial Intelligence techniques have proved to be very\nsuccessful when applied to problems in physical sciences. Here we apply an\nunsupervised Machine Learning (ML) algorithm called Principal Component\nAnalysis (PCA) as a tool to analyse the data from muon spectroscopy\nexperiments. Specifically, we apply the ML technique to detect phase\ntransitions in various materials. The measured quantity in muon spectroscopy is\nan asymmetry function, which may hold information about the distribution of the\nintrinsic magnetic field in combination with the dynamics of the sample. Sharp\nchanges of shape of asymmetry functions - measured at different temperatures -\nmight indicate a phase transition. Existing methods of processing the muon\nspectroscopy data are based on regression analysis, but choosing the right\nfitting function requires knowledge about the underlying physics of the probed\nmaterial. Conversely, Principal Component Analysis focuses on small differences\nin the asymmetry curves and works without any prior assumptions about the\nstudied samples. We discovered that the PCA method works well in detecting\nphase transitions in muon spectroscopy experiments and can serve as an\nalternative to current analysis, especially if the physics of the studied\nmaterial are not entirely known. Additionally, we found out that our ML\ntechnique seems to work best with large numbers of measurements, regardless of\nwhether the algorithm takes data only for a single material or whether the\nanalysis is performed simultaneously for many materials with different physical\nproperties.",
        "positive": "Two phase transitions driven by surface electron-doping in WTe$_2$: WTe$_2$ is a multifunctional quantum material exhibiting numerous emergent\nphases in which tuning of the carrier density plays an important role. Here we\ndemonstrate two non-monotonic changes in the electronic structure of WTe$_2$\nupon \\textit{in-situ} electron doping. The first phase transition is\ninterpreted in terms of a shear displacement of the top WTe$_2$ layer, which\nrealizes a local crystal structure not normally found in bulk WTe$_2$. The\nsecond phase transition is associated with stronger interactions between the\ndopant atoms and the host, both through hybridization and electric field. These\nresults demonstrate that electron-doping can drive structural and electronics\nchanges in bulk WTe$_2$ with implications for realizing nontrivial band\nstructure changes in heterointerfaces and devices."
    },
    {
        "anchor": "Tuning Transport Properties of Topological Edge States of Bi(111)\n  Bilayer Film by Edge Adsorption: Based on first-principles and tight-binding calculations, we report that the\ntransport properties of topological edge states of zigzag Bi(111) nanoribbon\ncan be significantly tuned by H edge adsorption. The Fermi velocity is\nincreased by one order of magnitude, as the Dirac point is moved from Brillouin\nzone boundary to Brillouin zone center and the real-space distribution of Dirac\nstates are made twice more delocalized. These intriguing changes are explained\nby an orbital filtering effect of edge H atoms, which removes certain\ncomponents of $p$ orbits of edge Bi atoms that reshapes the topological edge\nstates. In addition, the spin texture of the Dirac states is also modified,\nwhich is described by introducing an effective Hamiltonian. Our findings not\nonly are of fundamental interest but also have practical implications in\npotential applications of topological insulators.",
        "positive": "Single Crystal Growth and Spin Polarization Measurements of Diluted\n  Magnetic Semiconductor (BaK)(ZnMn)2As2: Recently a new type diluted magnetic semiconductor (BaK)(ZnMn)2As2 (BZA) with\nhigh Cure temperature (Tc) was discovered showing independent spin and charge\ndoping mechanism. This makes BZA a promising material for spintronics devices.\nHere we report for the first time the successful growth of BZA single crystal.\nAn Andreev reflection junction that can be used to evaluate spin polarization\nwas fabricated based on the BZA single crystal, a 66% spin polarization of the\nBZA single crystal was hence obtained by Andreev reflection spectroscopy\nanalysis."
    },
    {
        "anchor": "Low Effective Mass Leading to High Thermoelectric Performance: High Seebeck coefficient by creating large density of state (DOS) around the\nFermi level through either electronic structure modification or manipulating\nnanostructures, is commonly considered as a route to advanced thermoelectrics.\nHowever, large density of state due to flat bands leads to large effective\nmass, which results in a simultaneous decrease of mobility. In fact, the net\neffect of high effective mass is a lower thermoelectric figure of merit when\nthe carriers are predominantly scattered by acoustic phonons according to the\ndeformation potential theory of Bardeen-Shockley. We demonstrate the beneficial\neffect of light effective mass leading to high power factor in n-type\nthermoelectric PbTe, where doping and temperature can be used to tune the\neffective mass. This clear demonstration of the deformation potential theory to\nthermoelectrics shows that the guiding principle for band structure engineering\nshould be low effective mass along the transport direction.",
        "positive": "Machine-learning interatomic potentials for materials science: Large-scale atomistic computer simulations of materials rely on interatomic\npotentials providing computationally efficient predictions of energy and\nNewtonian forces. Traditional potentials have served in this capacity for over\nthree decades. Recently, a new class of potentials has emerged, which is based\non a radically different philosophy. The new potentials are constructed using\nmachine-learning (ML) methods and a massive reference database generated by\nquantum-mechanical calculations. While the traditional potentials are derived\nfrom physical insights into the nature of chemical bonding, the ML potentials\nutilize a high-dimensional mathematical regression to interpolate between the\nreference energies. We review the current status of the interatomic potential\nfield, comparing the strengths and weaknesses of the traditional and ML\npotentials. A third class of potentials is introduced, in which an ML model is\ncoupled with a physics-based potential to improve the transferability to\nunknown atomic environments. The discussion is focused on potentials intended\nfor materials science applications. Possible future directions in this field\nare outlined."
    },
    {
        "anchor": "Spin density in frustrated magnets under mechanical stress: Mn-based\n  antiperovskites: In this paper we present results of our calculations of the non-collinear\nspin density distribution in the systems with frustrated triangular magnetic\nstructure (Mn-based antiperovskite compounds, Mn_{3}AN (A=Ga, Zn)) in the\nground state and under external mechanical strain. We show that the spin\ndensity in the (111)-plane of the unit cell forms a \"domain\" structure around\neach atomic site but it has a more complex structure than the uniform\ndistribution of the rigid spin model, i.e. Mn atoms in the (111)-plane form\nnon-uniform \"spin clouds\", with the shape and size of these \"domains\" being\nfunction of strain. We show that both magnitude and direction of the spin\ndensity change under compressive and tensile strains, and the orientation of\n\"spin domains\" correlates with the reversal of the strain, i.e. switching\ncompressive to tensile strain (and vice versa) results in \"reversal\" of the\ndomains. We present analysis for the intra-atomic spin-exchange interaction and\nthe way it affects the spin density distribution. In particular, we show that\nthe spin density inside the atomic sphere in the system under mechanical stress\ndepends on the degree of localization of electronic states.",
        "positive": "Free, flexible and fast: orientation mapping using the multi-core and\n  GPU-accelerated template matching capabilities in the python-based open\n  source 4D-STEM analysis toolbox Pyxem: This work presents the new template matching capabilities implemented in\nPyxem, an open source Python library for analyzing four-dimensional scanning\ntransmission electron microscopy (4D-STEM) data. Template matching is a brute\nforce approach for deriving local crystal orientations. It works by comparing a\nlibrary of simulated diffraction patterns to experimental patterns collected\nwith nano-beam and precession electron diffraction (NBED and PED). This is a\ncomputationally demanding task, therefore the implementation combines\nefficiency and scalability by utilizing multiple CPU cores or a graphical\nprocessing unit (GPU). The code is built on top of the scientific python\necosystem, and is designed to support custom and reproducible workflows that\ncombine the image processing, template library generation, indexation and\nvisualisation all in one environment. The tools are agnostic to file size and\nformat, which is significant in light of the increased adoption of pixelated\ndetectors from different manufacturers. This paper details the implementation,\nvalidation, and benchmarking results of the method. The method is illustrated\nby calculating orientation maps of nanocrystalline materials and precipitates\nembedded in a crystalline matrix. The combination of speed and flexibility\nopens the door for automated parameter studies and real-time on-line\norientation mapping inside the TEM."
    },
    {
        "anchor": "Mixed valency in cerium oxide crystallographic phases: Determination of\n  valence of the different cerium sites by the bond valence method: We have applied the bond valence method to cerium oxides to determine the\noxidation states of the Ce ion at the various site symmetries of the crystals.\nThe crystals studied include cerium dioxide and the two sesquioxides along with\nsome selected intermediate phases which are crystallographically well\ncharacterized. Our results indicate that cerium dioxide has a mixed-valence\nground state with an f-electron population on the Ce site of 0.27 while both\nthe A- and C-sesquioxides have a nearly pure f^1 configuration. The Ce sites in\nmost of the intermediate oxides have non-integral valences. Furthermore, many\nof these valences are different from the values predicted from a naive\nconsideration of the stoichiometric valence of the compound.",
        "positive": "Origin of half-semimetallicity induced at interfaces of C-BN\n  heterostructures: First-principles density functional calculations are performed in C-BN\nheterojunctions. It is shown that the magnetism of the edge states in zigzag\nshaped graphene strips and polarity effects in BN strips team up to give a spin\nasymmetric screening that induces half-semimetallicity at the interface, with a\ngap of at least a few tenths of eV for one spin orientation and a tiny gap of\nhundredths of eV for the other. The dependence with ribbon widths is discussed,\nshowing that a range of ribbon widths is required to obtain\nhalf-semimetallicity. These results open new routes for tuning electronic\nproperties at nanointerfaces and exploring new physical effects similar to\nthose observed at oxide interfaces, in lower dimensions."
    },
    {
        "anchor": "Engineering magnetic topological insulators in Eu$_5M_2X_6$ Zintls: Magnetic topological insulator provide a prominent material platform for\nquantum anomalous Hall physics and axion electrodynamics. However, the lack of\nmaterial realizations with cleanly gapped surfaces hinders technological\nutilization of these exotic quantum phenomena. Here, using the Zintl concept\nand the properties of non-symmorphic space groups, we computationally engineer\nmagnetic topological insulators. Specifically, we explore Eu$_5M_2X_6$\n($M$=metal, $X$=pnictide) Zintl compounds and find that Eu$_5$Ga$_2$Sb$_6$,\nEu$_5$Tl$_2$Sb$_6$ and Eu$_5$In$_2$Bi$_6$ form stable structures with\nnon-trivial $\\mathbb{Z}_2$ indices. We also show that epitaxial and uniaxial\nstrain can be used to control the $\\mathbb{Z}_2$ index and the bulk energy gap.\nFinally, we discuss experimental progress towards the synthesis of the proposed\ncandidates and provide insights that can be used in the search for robust\nmagnetic topological insulators in Zintl compounds.",
        "positive": "Tailoring Plasmonic Metamaterials for DNA Molecular Logic Gates: Structural and functional information encoded in DNA combined with unique\nproperties of nanomaterials could be of use for the construction of novel\nbiocomputational circuits and intelligent biomedical nanodevices. However, at\npresent their practical applications are still limited by either low\nreproducibility of fabrication, modest sensitivity, or complicated handling\nprocedures. Here, we demonstrate the construction of label-free and switchable\nmolecular logic gates that use specific conformation modulation of a guanine-\nand thymine- rich DNA, while the optical readout is enabled by the tunable\nalphabetical metamaterials, which serve as a substrate for surface enhanced\nRaman spectroscopy (MetaSERS). By computational and experimental\ninvestigations, we present a comprehensive solution to tailor the plasmonic\nresponses of MetaSERS with respect to the metamaterial geometry, excitation\nenergy, and polarization. Our tunable MetaSERS-based DNA logic is simple to\noperate, highly reproducible, and can be stimulated by ultra-low concentration\nof the external inputs, enabling an extremely sensitive detection of mercury\nions."
    },
    {
        "anchor": "Optical orientation of Mn^2+ ions in GaAs: We report on optical orientation of Mn^2+ in bulk GaAs under application of\nweak longitudinal magnetic field (B <= 100 mT). The manganese spin polarization\nof 25% is directly evaluated using spin flip Raman scattering spectroscopy. The\ndynamical polarization of Mn^2+ occurs due to s-d exchange interaction with\noptically oriented conduction band electrons. Time-resolved photoluminescence\nuncovers nontrivial electron spin dynamics where the oriented Mn^2+ ions tend\nto stabilize the electron spin.",
        "positive": "Majority-Carrier Mobilities in Undoped and \\textit{n}-type Doped ZnO\n  Epitaxial Layers: Transparent and conductive ZnO:Ga thin films are prepared by laser\nmolecular-beam epitaxy. Their electron properties were investigated by the\ntemperature-dependent Hall-effect technique. The 300-K carrier concentration\nand mobility were about $n_s \\sim 10^{16}$ cm$^{-3}$ and 440 cm$^{2}$/Vs,\nrespectively. In the experimental `mobility vs concentration' curve, unusual\nphenomenon was observed, i.e., mobilities at $n_s \\sim 5\\times$ 10$^{18}$\ncm$^{-3}$ are significantly smaller than those at higher densities above $\\sim\n10^{20}$ cm$^{-3}$. Several types of scattering centers including ionized\ndonors and oxygen traps are considered to account for the observed dependence\nof the Hall mobility on carrier concentration. The scattering mechanism is\nexplained in terms of inter-grain potential barriers and charged impurities. A\ncomparison between theoretical results and experimental data is made."
    },
    {
        "anchor": "Quantum mechanical motion of off-center ion in external magnetic field: We consider the magnetostatic response to an external magnetic field of a\ncrystal containing off-center ions, such as Li^+ in KCl and KBr or the apical\noxygens O(A) in the LaSCO family of layered perovskites. Magnetic dipoles are\ndeduced from the matrix elements of the energy operator of a spinning particle\nin a magnetic field which particle also satisfies the nonlinear Mathieu\nequation. The magnetic moments are found to increase in magnitude as the system\ngoes from the lowest energy ground state to the higher lying excited states.\nOur conclusions are in concert with earlier studies of magnetic dipoles from\ncircular currents based on Ampere's theorem.",
        "positive": "Study of the buckling effects on the electrical and optical properties\n  of the group III-Nitride monolayers: We consider electronic and optical properties of group III-Nitride monolayers\nusing first-principle calculations. The group III-Nitride monolayers have flat\nhexagonal structures with almost zero planar buckling, $\\Delta$. By tuning the\n$\\Delta$, the strong $\\sigma\\text{-}\\sigma$ bond through sp$^2$ hybridization\nof a flat form of these monolayers can be changed to a stronger\n$\\sigma\\text{-}\\pi$ bond through sp$^3$ hybridization. Consequently, the band\ngaps of the monolayers are tuned due to a dislocation of the $s$- and\n$p$-orbitals towards the Fermi energy. The band gaps decrease with increasing\n$\\Delta$ for those flat monolayers, which have a band gap greater than $1.0$\neV, while no noticeable change or a flat dispersion of the band gap is seen for\nthe flat monolayers, that have a band gap less than $1.0$ eV. The decreased\nband gap causes a decrease in the excitation energy, and thus the static\ndielectric function, refractive index, and the optical conductivity are\nincreased. In contrast, the flat band gap dispersion of few monolayers in the\ngroup III-Nitride induces a reduction in the static dielectric function, the\nrefractive index, and the optical conductivity. We therefore confirm that\ntuning of the planar buckling can be used to control the physical properties of\nthese monolayers, both for an enhancement and a reduction of the optical\nproperties. These results are of interest for the design of optoelectric\ndevices in nanoscale systems."
    },
    {
        "anchor": "An ab-initio study on physical properties of Pd2+ incorporated double\n  perovskites CaPd3B4O12 (B = Ti, V): Numerous physical properties of CaPd3Ti4O12 (CPTO) and CaPd3V4O12 (CPVO)\ndouble perovskites have been explored based on density functional theory (DFT).\nThe calculated structural parameters fairly agree with the experimental data to\nconfirm their stability. The mechanical stability of these two compounds was\nclearly observed by the Born stability criteria. To rationalize the mechanical\nbehavior, we investigate elastic constants, bulk, shear and Young's modulus,\nPugh's ratio, Poisson's ratio and elastic anisotropy index. The ductility index\nconfirms that both materials are ductile in nature. The electronic band\nstructure of CPTO and CPVO reveals the direct band gap semiconducting in nature\nand metallic characteristics, respectively. The calculated partial density of\nstates indicates the strong hybridization between Pd 4d and O 2p orbital\nelectrons for CPTO and Pd 4d and V 3d O 2p for CPVO. The study of electronic\ncharge density map confirms the coexistence of covalent, ionic and metallic\nbonding for both compounds. Fermi surface calculation of CPVO ensures both\nelectron and hole like surfaces indicating the multiple band nature. In the\nmidst of optical properties, photoconductivity and absorption coefficient of\nboth compounds reveal well qualitative compliance with consequences of band\nstructure computations. Among the thermodynamic properties, the Debye\ntemperature has been calculated to correlate its topical features including\nthermoelectric behavior. The studied thermoelectric transport properties of\nCPTO yielded the Seebeck coefficient (186 microVK-1), power factor (11.9\nmicroWcm-1K-2) and figure of merit (ZT) value of about 0.8 at 800 K indicate\nthat this material could be a promising candidate for thermoelectric device\napplication.",
        "positive": "Approaching ideal graphene: The structure of hydrogen-intercalated\n  graphene on 6H-SiC(0001): We measure the adsorption height of hydrogen-intercalated quasi-free-standing\nmonolayer graphene on the (0001) face of 6H silicon carbide by the normal\nincidence x-ray standing wave technique. A density functional calculation for\nthe full ($6 \\sqrt{3} \\times 6 \\sqrt{3}$)-R30$^\\circ$ unit cell, based on a van\nder Waals corrected exchange correlation functional, finds a purely\nphysisorptive adsorption height in excellent agreement with experiments, a very\nlow buckling of the graphene layer, a very homogeneous electron density at the\ninterface and the lowest known adsorption energy per atom for graphene on any\nsubstrate. A structural comparison to other graphenes suggests that hydrogen\nintercalated graphene on 6H-SiC(0001) approaches ideal graphene."
    },
    {
        "anchor": "Control of phase ordering and elastic properties in phase field crystals\n  through three-point direct correlation: Effects of three-point direct correlation on properties of the phase field\ncrystal (PFC) modeling are examined, for the control of various ordered and\ndisordered phases and their coexistence in both three-dimensional and\ntwo-dimensional systems. Such effects are manifested via the corresponding\ngradient nonlinearity in the PFC free energy functional that is derived from\nclassical density functional theory. Their significant impacts on the stability\nregimes of ordered phases, phase diagrams, and elastic properties of the\nsystem, as compared to those of the original PFC model, are revealed through\nsystematic analyses and simulations. The nontrivial contribution from\nthree-point direct correlation leads to the variation of the critical point of\norder-disorder transition to which all the phase boundaries in the\ntemperature-density phase diagram converge. It also enables the variation and\ncontrol of system elastic constants over a substantial range as needed in\nmodeling different types of materials with the same crystalline structure but\ndifferent elastic properties. The capability of this PFC approach in modeling\nboth solid and soft matter systems is further demonstrated through the effect\nof three-point correlation on controlling the vapor-liquid-solid coexistence\nand transitions for body-centered cubic (bcc) phase and on achieving the\nliquid-stripe or liquid-lamellar phase coexistence. All these provide a\nvaluable and efficient method for the study of structural ordering and\nevolution in various types of material systems.",
        "positive": "Monolayer sorption of neon in mesoporous silica glass as monitored by\n  WAXS: We report measurements of the x-ray scattering intensity as mesoporous\nglasses are filled with Neon. We outline a simple model to account for the\nnon-linear increase in the intensity of the first peak in a liquid-like\ndiffraction pattern as a monolayer is formed. This allows us to demonstrate an\napproach for surface area determination which does not rely on thermodynamic\nmodels, and is therefore complimentary to existing models."
    },
    {
        "anchor": "Large Magnetoresistance in Compensated Semimetals TaAs$_2$ and NbAs$_2$: We report large magnetoresistance (MR) at low temperatures in\nsingle-crystalline nonmagnetic compounds TaAs$_2$ and NbAs$_2$. Both compounds\nexhibit parabolic-field-dependent MR larger than $5\\times10^3$ in a magnetic\nfield of 9 Tesla at 2 K. The MR starts to deviate from parabolic dependence\nabove 10 T and intends to be saturated in 45 T for TaAs$_2$ at 4.2 K. The Hall\nresistance measurements and band structural calculations reveal their\ncompensated semimetal characteristics. The large MR at low temperatures is\nascribed to a resonance effect of the balanced electrons and holes with large\nmobilities. We also discuss the relation of the MR and samples' quality for\nTaAs$_2$ and other semimetals. We found that the magnitudes of MR are strongly\ndependent on the samples' quality for different compounds.",
        "positive": "Ultrafast Momentum-Resolved Probing of Plasmon Thermal Dynamics with\n  Free Electrons: Current advances in ultrafast electron microscopy make it possible to combine\noptical pumping of a nanostructure and electron beam probing with\nsub{\\aa}ngstrom and femtosecond spatiotemporal resolution. We present a theory\npredicting that this technique can reveal a rich out-of-equilibrium dynamics of\nplasmon excitations in graphene and graphite samples. In a disruptive departure\nfrom the traditional probing of nanoscale excitations based on the\nidentification of spectral features in the transmitted electrons, we show that\nmeasurement of angle-resolved, energy-integrated inelastic electron scattering\ncan trace the temporal evolution of plasmons in these structures and provide\nmomentum-resolved mode identification, thus avoiding the need for\nhighly-monochromatic electron beams and the use of electron spectrometers. This\npreviously unexplored approach to study the ultrafast dynamics of optical\nexcitations can be of interest to understand and manipulate polaritons in 2D\nsemiconductors and other materials exhibiting a strong thermo-optical response."
    },
    {
        "anchor": "Recent advances in La2NiMnO6 Double Perovskites for various\n  applications; Challenges and opportunities: Double perovskites R2NiMnO6 (R= Rare earth element) (RNMO) are a significant\nclass of materials owing to their Multifunctional properties with structural\nmodifications. In particular, multifunctional double perovskite oxides\nLa2NiMnO6 (LNMO) which possess both electric and magnetic orderings, chemical\nflexibility, versatility, and indispensable properties like high ferromagnetic\ncurie temperature, high absorption rates, dielectrics, etc. have drawn a lot of\nattention due their rich physics and diverse applications in various\ntechnology. This justifies the intense research in this class of materials, and\nthe keen interest they are subject to both the fundamental and practical side.\nIn view of the demands of this material in lead-free perovskite solar cells,\nphotocatalytic degradation of organic dyes, clean hydrogen production, electric\ntuneable devices, Fuel cells, gas sensing, and Biomedical applications, there\nis a need for an overview of all the literature so far, the ongoing research\nand the future prospective. This review summarised all the Physical and\nStructural Properties of LNMO such as electric, magnetic, catalytic, and\ndielectric properties with their underlying mechanisms. This review article\nprovides insight into the scope of studies in LNMO material for exploring\nunexposed properties in new material research and to identify areas of future\ninvestigation of the materials in the double perovskite family.",
        "positive": "The nature of highly anisotropic free-electron-like states in a\n  glycinate monolayer on Cu(100): The free-electron-like state observed in a scanning tunneling spectroscopy\nstudy of a chiral p(2x4) monolayer of glycinate ions on the Cu(100) surface [K.\nKanazawa et al, J. Am. Chem. Soc. 129, 740 (2007)] is shown from density\nfunctional theory calculations to originate from a Cu Shockley surface state at\nthe surface Brillouin zone boundary of the clean surface with highly\nanisotropic dispersion. The presence of the glycinate ions on the surface\ncauses a dramatically enhanced tunneling into this surface state that is\notherwise not observed in tunneling on the bare surface."
    },
    {
        "anchor": "Kinetics of Exciton Self-Trapping Induced Defect Accumulation in\n  Rare-Gas Solids: The kinetics of the process of defect accumulation in rare-gas solids as a\nresult of exciton self-trapping was studied using the selective vacuum\nultraviolet photoluminescence method for monitoring of the crystal structure of\nthe samples. The simple kinetic model of defect accumulation in rare-gas\nsamples was applied to the fitting of the dose dependences of luminescence from\nsolid Xe and Ne. The characteristic kinetic parameters were obtained by linear\ntransformation of the time dependence of luminescence intensity of \"defect\"\nsubbands.",
        "positive": "Fluctuations of the Magnetization in Thin Films due to Conduction\n  Electrons: A detailed analysis of damping and noise due to a {\\it sd}-interaction in a\nthin ferromagnetic film sandwiched between two large normal metal layers is\ncarried out. The magnetization is shown to obey in general a non-local equation\nof motion which differs from the the Gilbert equation and is extended to the\nnon-adiabatic regime. To lowest order in the exchange interaction and in the\nlimit where the Gilbert equation applies, we show that the damping term is\nenhanced due to interfacial effects but it also shows oscillations as a\nfunction of the film thickness. The noise calculation is however carried out to\nall orders in the exchange coupling constant. The ellipticity of the precession\nof the magnetization is taken into account. The damping is shown to have a\nGilbert form only in the adiabatic limit while the relaxation time becomes\nstrongly dependent on the geometry of the thin film. It is also shown that the\ninduced noise characteristic of sd-exchange is inherently colored in character\nand depends on the symmetry of the Hamiltonian of the magnetization in the\nfilm. We show that the sd-noise can be represented in terms of an external\nstochastic field which is white only in the adiabatic regime. The temperature\nis also renormalized by the spin accumulation in the system. For large\nintra-atomic exchange interactions, the Gilbert-Brown equation is no longer\nvalid."
    },
    {
        "anchor": "Homogeneously bright, flexible and foldable lighting devices with\n  functionalised graphene electrodes: Alternating current electroluminescent technology allows the fabrication of\nlarge area, flat and flexible lights. Presently the maximum size of a\ncontinuous panel is limited by the high resistivity of available transparent\nelectrode materials causing a visible gradient of brightness. Here, we\ndemonstrate that the use of the best known transparent conductor\nFeCl$_{3}$-intercalated few-layer graphene boosts the brightness of\nelectroluminescent devices by 49$\\%$ compared to pristine graphene. Intensity\ngradients observed for high aspect ratio devices are undetectable when using\nthese highly conductive electrodes. Flat lights on polymer substrates are found\nto be resilient to repeated and flexural strains.",
        "positive": "Carbon Ejection from a SiO2/SiC(0001) Interface by Annealing in\n  High-Purity Ar: We found that carbon-associated byproducts formed at the dry-oxidized\nSiO2/SiC(0001) interface could be decomposed and be taken out to the SiO2 side\nby high-purity Ar annealing. We evaluated the concentration of the ejected\ncarbon atoms in the SiO2 by secondary ion mass spectrometry, and discovered\nthat it clearly depends on the condition of oxide formation (dry-oxidation,\nnitridation treatment, and phosphorus treatment). This work provides an\nindirect but unambiguous evidence for the carbon-byproducts existing at the\nSiO2/SiC interfaces, and also indicates that the phosphorus treatment removes\nthe carbon-byproducts, leading to significant reduction of interface defects."
    },
    {
        "anchor": "Comment on \"On the importance of the free energy for elasticity under\n  pressure\": Marcus et al. (Marcus P, Ma H and Qiu S L 2002 J. Phys.: Condens. Matter 14\nL525) claim that thermodynamic properties of materials under pressure must be\ncomputed using the Gibbs free energy $G$, rather than the internal energy $E$.\nMarcus et al. state that ``The minima of $G$, but not of $E$, give the\nequilibrium structure; the second derivatives of $G$, but not of $E$, with\nrespect to strains at the equilibrium structure give the equilibrium elastic\nconstants.'' Both statements are incorrect.",
        "positive": "Bidirectional switching assisted by interlayer exchange coupling in\n  asymmetric magnetic tunnel junctions: We study the combined effects of spin transfer torque, voltage modulation of\ninterlayer exchange coupling and magnetic anisotropy on the switching behavior\nof perpendicular magnetic tunnel junctions (p-MTJs). In asymmetric p-MTJs, a\nlinear-in-voltage dependence of interlayer exchange coupling enables the\neffective perpendicular anisotropy barrier to be lowered for both voltage\npolarities. This mechanism is shown to reduce the critical switching current\nand effective activation energy. Finally, we analyze the possibility of having\nswitching via interlayer exchange coupling only."
    },
    {
        "anchor": "Probing the SO$_2$ adsorption mechanism in Hofmann clathrates via\n  inelastic neutron scattering and density functional theory calculations: The adsorption mechanism of SO2 in the Hofmann-like coordination polymer\nFe(pz)[Pt(CN)4] is studied using inelastic neutron scattering and density\nfunctional theory calculations. We find that the most important spectral change\nupon gas adsorption is the blueshift of the low energy peak found at 100 cm-1,\na feature that is fully confirmed by the computed neutron-weighted phonon\ndensity of states. Our calculations suggest that the origin of this change is\ntwofold: i) an increase in the force constant of the cyanide out-of-plane\nmovement due to the binding of the gas onto the Pt(CN)4 plane, and ii) the\nhampered rotation of the pyrazine due to steric hindrance. The high energy\nregion of the neutron scattering data whose spectral weight is dominated by the\ninternal vibrations of the pyrazine is negligibly affected by the presence of\nthe gas as expected from a physisorption type of binding.",
        "positive": "Comment on the stability of decorated C 48 B 12 heterofullerene: A good hydrogen storage material should adsorb hydrogen in high\nconcentrations and with optimal binding energies. Numerous mixed carbon boron\nfullerenes which are decorated with metal atoms were previously constructed by\nhand and proposed as a promising material in this context. We present a fully\nab-initio, unbiased structure search in the configurational space of decorated\nC48B12 and find that most of the hitherto postulated ground state structures\nare not ground states. We determine the energetically lowest configurations for\nBe, Ca, Li and Sc decorated C48B12 clusters."
    },
    {
        "anchor": "In situ observation of the generation and annealing kinetics of E'\n  centers induced in amorphous SiO2 by 4.7eV laser irradiation: The kinetics of E' centers induced in silica by 4.7eV laser irradiation was\ninvestigated observing in situ their optical absorption band at 5.8 eV. After\nexposure the defects decay due to reaction with diffusing molecular hydrogen of\nradiolytic origin. Hydrogen-related annealing is active also during exposure\nand competes with the photo-induced generation of the centers until a\nsaturation is reached. The concentrations of E' and H2 at saturation are\nproportional, so indicating that the UV-induced generation processes of the two\nspecies are correlated. These results are consistent with a model in which E'\nand hydrogen are generated from a common precursor Si-H.",
        "positive": "Responses of Pre-transitional Materials with Stress-Generating Defects\n  to External Stimuli: Superelasticity, Supermagnetostriction, Invar and\n  Elinvar Effects: We considered a generic case of pre-transitional materials with static\nstress-generating defects, dislocations and coherent nano-precipitates, at\ntemperatures close but above the starting temperature of martensitic\ntransformation, Ms. Using the Phase Field Microelasticity theory and 3D\nsimulation, we demonstrated that the local stress generated by these defects\nproduces equilibrium nano-size martensitic embryos (MEs) in pre-transitional\nstate, these embryos being orientation variants of martensite. This is a new\ntype of equilibrium: the thermoelastic equilibrium between the MEs and parent\nphase in which the total volume of MEs and their size are equilibrium internal\nthermodynamic parameters. This thermoelastic equilibrium exists only in\npresence of the stress-generating defects. Cooling the pre-transitional state\ntowards Ms or applying the external stimuli, stress or magnetic field, results\nin a shift of the thermoelastic equilibrium provided by a reversible\nanhysteretic growth of MEs that results in a giant ME-generated macroscopic\nstrain. In particular, this effect can be associated with the diffuse phase\ntransformations observed in some ferroelectrics above the Curie point. It is\nshown that the ME-generated strain is giant and describes a superelasticity if\nthe applied field is stress. It describes a super magnetostriction if the\nmartensite (or austenite) are ferromagnetic and the applied field is a magnetic\nfield. In general, the material with defects can be a multiferroic with a giant\nmultiferroic response if the parent and martensitic phase have different\nferroic properties. Finally the ME-generated strain may explain or, at least,\ncontribute to the Invar and Elinvar effects that are typically observed in\npre-transitional austenite. The thermoelastic equilibrium and all these effects\nexist only if the interaction between the defects and MEs is infinite-range."
    },
    {
        "anchor": "Octonacci Photonic Quasicrystals: We study theoretically the transmission spectra in one-dimensional photonic\nquasicrystals, made up of SiO$_2$($A$) and TiO$_2$($B$) materials, organized\nfollowing the Octonacci sequence, where the $n$th-stage of the multilayer\n$S_{n}$ is given by the rule $S_{n}=S_{n-1}S_{n-2}S_{n-1}$, for $n\\geq 3$ and\nwith $S_{1}=A$ and $S_{2}=B$. The expression for transmittance was obtained by\nemploying a theoretical calculation based in the transfer-matrix method. To\nnormally incident waves, we observe that, for a same generation, the\ntransmission spectra for TE and TM waves are equal, at least qualitatively, and\nthey present a scaling property where a self-similar behavior is obtained, as\nan evidence that these spectra are fractals. The spectra show regions where the\nomnidirectional band gaps emerges for specific generations of Octonacci\nphotonic structure, except to TM waves. For TE waves, we note that all of them\nhave the almost same width, for different generations. We also report the\nlocalization of modes as a consequence of the quasiperiodicity of the\nheterostructure",
        "positive": "Unleashing the Potential of Li-Metal Batteries A Breakthrough Ultra-High\n  Room-Temperature Ionic Conductivity Composite Solid-State Electrolyte: The solid-state electrolyte is critical for achieving next-generation high\nenergy density and high-safety batteries. Solid polymer electrolytes (SPEs)\npossess great potential for commercial application owing to their compatibility\nwith the existing manufacturing systems. However, unsatisfactory\nroom-temperature ionic conductivity severely limits its application. Herein, an\nultra-high room-temperature ionic conductivity composite solid-state\nelectrolyte (CSE) is prepared by introducing an appropriate amount of SiO2\nnanosphere to the PVDF-HFP matrix. By doing this, the polymer particles are\ndivided and surrounded by SiO2. And the interface amount is maximized resulting\nin the high ionic conductivity of 1.35 mS cm-1 under room temperature. In\naddition, the CSE shows a wide electrochemical window of 4.95 V and a moderate\nLi+ transference number of 0.44. The CSE demonstrates good stability with Li\nanode, with Li symmetric cells that could cycle 1000 h at a current density of\n0.2 mA cm-2. The full cell assembled with LiFePO4 (LFP) and Li metal displays a\nhigh reversible specific capacity of 157.8 mAh g-1 at 0.1C, and it could\nmaintain 92.9% of initial capacity after 300 cycles at 3C. Moreover, the\nstrategy is applied in solid-state sodium/potassium batteries and displays\nexcellent performance."
    },
    {
        "anchor": "Van der Waals forces from first principles for periodic systems:\n  Application to graphene-water interactions: We extend the method of Silvestrelli [P. L. Silvestrelli, J. Chem. Phys. 139,\n054106 (2013)] to approximate long-range van der Waals interactions at the\ndensity functional theory level based on maximally localized Wannier functions\ncombined with the quantum harmonic oscillator model, to periodic systems.\nApplying this scheme to study London dispersion forces between graphene and\nwater layers, we demonstrate that collective many-body effects beyond simple\nadditive pair-wise interactions are essential to accurately describe van der\nWaals forces.",
        "positive": "Stabilizing sample-wide Kekul\u00e9 orders in graphene/transition metal\n  dichalcogenide heterostructures: Kekul\\'e phases are Peierls-like lattice distortions in graphene that are\npredicted to host novel electronic states beyond graphene (1-8). Although the\nKekul\\'e phases are realized in graphene through introducing electron-electron\ninteractions at high magnetic fields (9-11) or adatom superlattices (12-15), it\nis still an extremely challenge to obtain large-area graphene Kekul\\'e phases\nin experiment. Here we demonstrate that sample-wide Kekul\\'e distortions in\ngraphene can be stabilized by using transition metal dichalcogenides (TMDs) as\nsubstrates and the induced Kekul\\'e orders are quite robust in the whole\ngraphene/TMDs heterostructures with different twist angles. The commensurate\nstructures of the heterostructures provide periodic scattering centers that\nbreak the translational symmetry of graphene and couple electrons of the two\nvalleys in graphene, which tips the graphene toward global Kekul\\'e density\nwave phases. Unexpectedly, three distinct Kekul\\'e bond textures stabilized at\nvarious energies are directly imaged in every graphene/TMDs heterostructure.\nOur results reveal an unexpected sensitivity of electronic properties in\ngraphene to the supporting substrates and provide an attractive route toward\ndesigning novel phases in graphene/TMDs heterostructures."
    },
    {
        "anchor": "Microstructure and mechanical properties of mechanically-alloyed\n  CoCrFeNi high-entropy alloys using low ball-to-powder ratio: High-entropy alloys are extensively studied due to their very promising\nproperties. However manufacturing methods currently used to prepare HEAs are\ncomplicated, costly, and likely non-industrially scalable processes. This\nlimits their evolution and poses questions regarding the material's\napplicability in the future. Considering the abovementioned point, we developed\na novel methodology for efficient HEA production using a low ball-to-powder\nratio (BPR). Using different milling times, we manufactured four HEA powder\nprecursors using a BPR of 5:1, which were later sintered via the Spark Plasma\nSintering technique and heat treated. Microstructural characterization was\nperformed by optical microscopy, Scanning Electron Microscopy equipped with EDS\nand EBSD detectors, and X-ray diffraction. Mechanical properties were measured\nusing nano and microhardness techniques. In this work, we follow the structural\nevolution of the material and connect it with the strengthening effect as a\nfunction of milling time. Furthermore, we discuss the impact of different\nsintering and annealing conditions, proving that HEAs characterized by high\nmechanical properties may be manufactured using low BPR.",
        "positive": "Braiding lateral morphotropic grain boundary in homogeneitic oxides: Interfaces formed by correlated oxides offer a critical avenue for\ndiscovering emergent phenomena and quantum states. However, the fabrication of\noxide interfaces with variable crystallographic orientations and strain states\nintegrated along a film plane is extremely challenge by conventional\nlayer-by-layer stacking or self-assembling. Here, we report the creation of\nmorphotropic grain boundaries (GBs) in laterally interconnected cobaltite\nhomostructures. Single-crystalline substrates and suspended ultrathin\nfreestanding membranes provide independent templates for coherent epitaxy and\nconstraint on the growth orientation, resulting in seamless and atomically\nsharp GBs. Electronic states and magnetic behavior in hybrid structures are\nlaterally modulated and isolated by GBs, enabling artificially engineered\nfunctionalities in the planar matrix. Our work offers a simple and scalable\nmethod for fabricating unprecedented innovative interfaces through controlled\nsynthesis routes as well as provides a platform for exploring potential\napplications in neuromorphics, solid state batteries, and catalysis."
    },
    {
        "anchor": "Crystallographic and magnetic structures of the VI$_3$ and LiVI$_3$ van\n  der Waals compounds: Two-dimensional (2D) layered magnetic materials are generating a great amount\nof interest for the next generation of electronic devices thanks to their\nremarkable properties associated to spin dynamics. The recently discovered\nlayered VI$_3$ ferromagnetic phase belongs to this family, although a full\nunderstanding of its properties is limited by an ill-defined crystallographic\nstructure. This is not any longer true. Here, we investigate the VI$_3$ crystal\nstructure upon cooling using both synchrotron X-ray and neutron powder\ndiffraction and provide structural models for the two structural transitions\noccurring at 76 K and 32 K. Moreover, we confirm by magnetic measurements that\nVI$_3$ becomes ferromagnetic at 50 K and discuss the difficulty of solving its\nfull magnetic structure by neutrons. We equally determined the magnetic\nproperties of our recently reported LiVI$_3$ phase, which is alike the\nwell-known CrI$_3$ ferromagnetic phase in terms of electronic and\ncrystallographic structures and found to our surprise an antiferromagnetic\nbehavior with a N\\'eel temperature of 12 K. Such a finding provides extra clues\nfor a better understanding of magnetism in these low dimension compounds.\nFinally, the easiness of preparing novel Li-based 2D magnetic materials by\nchemical/electrochemical means opens wide the opportunity to design materials\nwith exotic properties.",
        "positive": "Phase transitions, energy storage performances and electrocaloric effect\n  of the lead-free Ba0.85Ca0.15Zr0.10Ti0.90O3 ceramic relaxor: Lead-free Ba0.85Ca0.15Zr0.10Ti0.90O3 (BCZT) ceramic exhibits excellent\ndielectric, ferroelectric and piezoelectric properties at the Morphotropic\nPhase Boundary (MPB). Previously, we demonstrated that the use of the anionic\nsurfactant Sodium Dodecyl Sulfate (SDS, NaC12H25SO4) could enhance the\ndielectric properties of BCZT ceramic using surfactant-assisted solvothermal\nprocessing [1]. In the present study, structural, dielectric, ferroelectric\nproperties, as well as electrocaloric effect and energy storage performances of\nthis BCZT ceramic were thoroughly investigated. X-ray diffraction (XRD)\nmeasurements revealed the presence of single perovskite phase at room\ntemperature with the coexistence of orthorhombic and tetragonal symmetries.\nIn-situ Raman spectroscopy results confirmed the existence of all phase\ntransitions from rhombohedral through orthorhombic and tetragonal to cubic\nsymmetries when the temperature varies as reported in undoped-BaTiO3. Evolution\nof energy storage performances with temperature have been investigated. BCZT\nceramic exhibits a high energy storage efficiency of ~80% at 120 {\\deg}C. In\naddition, the electrocaloric responsivity was found to be 0.164.10-6 K.m/V at\n360 K."
    },
    {
        "anchor": "Accurate finite-difference micromagnetics of magnets including RKKY\n  interaction -- analytical solution and comparison to standard micromagnetic\n  codes: Within this paper we show the importance of accurate implementations of the\nRKKY interactions for antiferromagnetically coupled ferromagnetic layers with\nthicknesses exceeding the exchange length. In order to evaluate the performance\nof different implementations of RKKY interaction, we develop a benchmark\nproblem by deriving the analytical formula for the saturation field of two\ninfinitely thick magnetic layers that are antiparallelly coupled. This\nbenchmark problem shows that state-of-the-art implementations in commonly used\nfinite-difference codes lead to errors of the saturation field that amount to\nmore than 20% for mesh sizes of 2 nm which is well below the exchange length of\nthe material. In order to improve the accuracy, we develop higher order cell\nbased and nodal based finite-difference codes that significantly reduce the\nerror compared to state-of-the-art implementations. For the second order cell\nbased and first order nodal based finite element approach the error of the\nsaturation field is reduced by about a factor of 10 (2% error) for the same\nmesh size of 2 nm.",
        "positive": "Electronic and optical properties of beryllium chalcogenides/silicon\n  heterostructures: We have calculated electronic and optical properties of\nSi/BeSe$_{0.41}$Te$_{0.59}$ heterostructures by a semiempirical $sp^{3}s^{*}$\ntight-binding method. Tight-binding parameters and band bowing of\nBeSe$_{0.41}$Te$_{0.59}$ are considered through a recent model for highly\nmismatched semiconductor alloys. The band bowing and the measurements of\nconduction band offset lead to a type II heterostucture for\nSi/BeSe$_{0.41}$Te$_{0.59}$ with conduction band minimum in the Si layer and\nvalence band maximum in the BeSe$_{0.41}$Te$_{0.59}$ layer. The electronic\nstructure and optical properties of various (Si$_{2})_{n\n}$/(BeSe$_{0.41}$Te$_{0.59})_{m}$ [001] superlattices have been considered. Two\nbands of interface states were found within the bandgap of bulk Si. Our\ncalculations indicate that the optical edges are below the fundamental bandgap\nof bulk Si and the transitions are optically allowed."
    },
    {
        "anchor": "Neutron Radiography Analysis of a Transient Liquid Phase Joint: Neutron radiography in many cases is the only non-destructive technique\navailable for the analysis of a wide range of samples from metallurgy,\nmaterials engineering and materials testing. In this paper the potential of the\ntechnique is illustrated for a transient liquid phase (TLP) joint.\n  TLP bonding produces interface free and stress free joints. The quality and\nproperties of the joint depend on the diffusion of an interlayer into the base\nmaterial. A TLP joint is visualised and the diffusion profile of the boron\ncontained in the bonding additives is determined. Parameters of the bonding\nprocess are determined quantitatively from this profile, and flaws in the joint\nare detected.",
        "positive": "Exact-Exchange Spin-Current Density-Functional Theory: A spin-current density-functional theory (SCDFT) is introduced, which takes\ninto account currents of the spin-density and thus currents of the\nmagnetization in addition to the electron density, the non-collinear\nspin-density, and the density current, which are considered in standard current\nspin-density-functional theory. An exact exchange Kohn-Sham formalism based on\nSCDFT is presented, which represents a general framework for the treatment of\nmagnetic and spin properties. As illustration an oxygen atom in a magnetic\nfield is treated with the new approach."
    },
    {
        "anchor": "In-situ EXAFS study on the thermal decomposition of TiH2: Thermal decomposition behaviors of TiH2 powder under a flowing helium\natmosphere and in a low vacuum condition have been studied by using in-situ\nEXAFS technique. By an EXAFS analysis containing the multiple scattering paths\nincluding H atoms, the changes of hydrogen stoichiometric ratio and the phase\ntransformation sequence are obtained. The results demonstrate that the initial\ndecomposition temperature is dependent on experimental conditions, which\noccurs, respectively, at about 300 and 400 degree in a low vacuum condition and\nunder a flowing helium atmosphere. During the decomposition process of TiH2 in\na low vacuum condition, the sample experiences a phase change process:\n{\\delta}(TiH2) - {\\delta}(TiHx) - {\\delta}(TiHx)+{\\beta}(TiHx) -\n{\\delta}(TiHx)+{\\beta}(TiHx)+{\\alpha}(Ti) - {\\beta}(TiHx)+{\\alpha}(Ti) -\n{\\alpha}(Ti)+{\\beta}(Ti). This study offers a way to detect the structural\ninformation of hydrogen. A detailed discussion about the decomposition process\nof TiH2 is given in this paper.",
        "positive": "Atom-by-atom design of metal oxide catalysts for the oxygen evolution\n  reaction with machine learning: Green hydrogen production is crucial for a sustainable future, but current\ncatalysts for the oxygen evolution reaction (OER) suffer from slow kinetics,\ndespite many efforts to produce optimal designs, particularly through the\ncalculation of descriptors for activity. In this study, we develop a dataset of\ndensity functional theory calculations of bulk and surface perovskite oxides,\nand adsorption energies of OER intermediates, which includes compositions up to\nquaternary and facets up to (555). We demonstrate that per-site properties of\nperovskite oxides such as Bader charge or band center can be tuned through\nelement substitution and faceting, and develop a machine learning model that\naccurately predicts these properties directly from the local chemical\nenvironment. We leverage these per-site properties to identify promising\nperovskites with high theoretical OER activity. The identified design\nprinciples and promising new materials provide a roadmap for closing the gap\nbetween current artificial catalysts and biological enzymes."
    },
    {
        "anchor": "X-ray magnetic circular dichroism study of epitaxial magnetite ultrathin\n  film on MgO (100): The spin and orbital magnetic moments of the Fe3O4 epitaxial ultrathin film\nsynthesized by plasma assisted simultaneous oxidization on MgO(100) have been\nstudied with X-ray magnetic circular dichroism (XMCD). The ultrathin film\nretains a rather large total magnetic moment, i.e. (2.7+-0.15) uB/f.u., which\nis ~ 70% of that for the bulk-like Fe3O4. A significant unquenched orbital\nmoment up to (0.54+-0.05) uB/f.u. was observed, which could come from the\nsymmetry breaking at the Fe3O4/MgO interface. Such sizable orbital moment will\nadd capacities to the Fe3O4-based spintronics devices in the magnetization\nreversal by the electric field.",
        "positive": "Structural and vibrational properties of two-dimensional $\\rm Mn_xO_y$\n  nanolayers on Pd(100): Using different experimental techniques combined with density functional\nbased theoretical methods we have explored the formation of\ninterface-stabilized manganese oxide structures grown on Pd(100) at\n(sub)monolayer coverage. Amongst the multitude of phases experimentally\nobserved we focus our attention on four structures which can be classified into\ntwo distinct regimes, characterized by different building blocks. Two\noxygen-rich phases are described in terms of MnO(111)-like O-Mn-O trilayers,\nwhereas the other two have a lower oxygen content and are based on a\nMnO(100)-like monolayer structure. The excellent agreement between calculated\nand experimental scanning tunneling microscopy images and vibrational electron\nenergy loss spectra allows for a detailed atomic description of the explored\nmodels."
    },
    {
        "anchor": "Intergranular Hotspots: A Molecular Dynamics Study on the Influence of\n  Compressive and Shear Work: Numerous crystal- and microstructural-level mechanisms are at play in the\nformation of hotspots, which are known to govern high explosive initiation\nbehavior. Most of these mechanisms, including pore collapse, interfacial\nfriction, and shear banding, involve both compressive and shear work done\nwithin the material and have thus far remained difficult to separate. We assess\nhotspots formed at shocked crystal-crystal interfaces using quasi-1D molecular\ndynamics simulations that isolate effects due to compression and shear. Two\nhigh explosive materials are considered (TATB and PETN) that exhibit distinctly\ndifferent levels of molecular conformational flexibility and crystal packing\nanisotropy. Temperature and intra-molecular strain energy localization in the\nhotspot is assessed through parametric variation of the crystal orientation and\ntwo velocity components that respectively modulate compression and shear work.\nThe resulting hotspots are found to be highly localized to a region within 5-20\nnm of the crystal-crystal interface. Compressive work plays a considerably\nlarger role in localizing temperature and intra-molecular strain energy for\nboth materials and all crystal orientations considered. Shear induces a\nmoderate increase in energy localization relative to unsheared cases only for\nrelatively weak compressive shock pressures of approximately 10 GPa. These\nresults help isolate and rank the relative importance of hotspot generation\nmechanisms and are anticipated to guide the treatment of crystal-crystal\ninterfaces in coarse-grained models of polycrystalline high explosive\nmaterials.",
        "positive": "Role of oxygen interstitials in Zn1-xGaxO for faster response to UV\n  light: ZnO doped with Gallium (Ga3+) demonstrates better crystalline nature and\nconductivity increases. Latent defect states are suppressed. However, due to\nthe larger charge of Ga3+ oxygen interstitials are generated which control the\nsensing speed. The conductance increases as a consequence of reduced defect\nstates, especially the oxygen vacancies. The photocurrent increases with Galium\nincorporation, but a more intense increase in the current reduces the\nsensitivity."
    },
    {
        "anchor": "Intracrystalline inclusions within single crystalline hosts: from\n  biomineralization to bio-inspired crystal growth: Many crystals in nature exhibit fascinating mechanical, optical, magnetic and\nother characteristics. One of the reasons for this phenomenon has to do with\nthe presence of specific organic molecules that are tightly associated with the\nmineral. Over the years, some organic crystals have been found to be located\nwithin the lattices of their singlecrystalline biogenic hosts. A number of\nquestions remain unanswered: for example, how do these molecules become\nincorporated and what is their function? In this review we survey the gradual\nrefinement of the above mentioned finding in biogenic crystals, with the object\nof tracing the acquisition of our fundamental knowledge in this field during\nthe last 50 years. We highlight the progress made in understanding the function\nand significance of this intracrystalline organic matter, from the earliest\nobservations of this phenomenon in a biological system to the highly promising\nrecent achievements in bio-inspired material synthesis, where intracrystalline\nmolecules have been used in many studies to synthesize numerous synthetic\nnanohybrid composites with fascinating new properties.",
        "positive": "Estimating the Effective Elasticity Properties of a Diamond/$\u03b2$-SiC\n  Composite Thin Film by 3D Reconstruction and Numerical Homogenization: The main aim of the present work is to estimate the effective elastic\nstiffnesses of a two-phase diamond/$\\beta$-SiC composite thin film that is\nfabricated by chemical vapor deposition. The parameters of linear elasticity\nare determined by numerical homogenization. The database is sparse since for\nthe 3D volume of interest only two micrographs displaying the phase\ndistributions in perpendicular planes are available; micrographs each of a\ncross-section and the surface of the thin film. A representative volume element\n(RVE) is reconstructed by an optimization software and by means of identified\nmaterial symmetries in 2D of the specimen. The elastic homogenization results\nindicate that the two-phase diamond/$\\beta$-SiC composite exhibits the behavior\nof transverse isotropy, for which the set of six independent material\nparameters is identified."
    },
    {
        "anchor": "Ab-initio study of structural, elastic, electronic, optical and\n  thermodynamic properties of MgV2O6: We have performed ab-initio calculations using plane-wave ultraviolet\npseudopotential technique based on the density-functional theory (DFT) to study\nthe structural, mechanical, electronic, optical and thermodynamic properties of\northorhombic MgV2O6. The calculated lattice parameters are in good agreement\nwith the available experimental data. The second-order elastic constants and\nthe other relevant quantities such as the Youngs modulus, shear modulus,\nPoissons ratio, compressibility, anisotropy factor, sound velocity, and Debye\ntemperature have been calculated. After analyzing the calculated elastic\nconstants, it is shown that the compound under study is mechanically stable.\nThe analysis of the electronic band structure shows that this compound reveals\nsemiconducting nature with band gap 2.195 eV and the contribution predominantly\ncomes from O-2s states.",
        "positive": "On the Mechanical and Thermal Stability of Free-standing Monolayer\n  Amorphous Carbon: Recently (C.-T. Toh et al., Nature 577, 199 (2020)), the first synthesis of\nfree-standing monolayer amorphous carbon (MAC) was achieved. MAC is a pure\ncarbon structure composed of five, six, seven and eight atom rings randomly\ndistributed. MAC proved to be surprisingly stable and highly fracture\nresistant. Its electronic properties are similar to boron nitride. In this\nwork, we have investigated the mechanical properties and thermal stability of\nMAC models using fully-atomistic reactive molecular dynamics simulations. For\ncomparison purposes, the results are contrasted against pristine graphene (PG)\nmodels of similar dimensions. Our results show that MAC and PG exhibit distinct\nmechanical behavior and fracture dynamics patterns. While PG after a critical\nstrain threshold goes directly from elastic to brittle regimes, MAC shows\ndifferent elastic stages between these two regimes. Remarkably, MAC is\nthermally stable up to 3600 K, which is close to the PG melting point. These\nexceptional physical properties make MAC-based materials promising candidates\nfor new technologies, such as flexible electronics."
    },
    {
        "anchor": "High Capacity Hydrogen Storage on Zirconium decorated \u03b3-graphyne:\n  A systematic first-principles study: In this work, we investigate the hydrogen-storage properties of Zr-decorated\n$\\gamma$-graphyne monolayer employing Density Functional Theory (DFT) for green\nenergy storage. We predict that each Zr atom decorated on graphyne sheet (2D)\ncan adsorb up to seven H$_2$ molecules with an average adsorption energy of\n-0.44 eV/H$_2$, leading to a hydrogen gravimetric density of 7.95 wt%, and\ndesorption temperature of 574 K, particularly suited to fuel-cell applications.\nDecorated Zr atom strongly attached to graphyne due to charge transfer from Zr\nto graphyne sheet. Hydrogen molecules adsorb on Zr decorated graphyne with\nKubas type of interaction. The 4.05 eV diffusion energy barrier between Zr\ndecorated position, and its neighboring pores may avoid the metal-metal (Zr-Zr)\nclustering. The stability of Zr+$\\gamma$-graphyne is confirmed by performing\nab-initio molecular dynamics simulations at room temperature and at estimated\naverage desorption temperature. Hence, our calculations show Zr functionalized\non $\\gamma$-graphyne could be a promising solid-state hydrogen storage\nmaterial.",
        "positive": "Hybrid-Functional Calculations of Electronic Structure and Phase\n  Stability of MO (M = Zn, Cd, Be, Mg, Ca, Sr, Ba) and Related Ternary Alloy\n  M$_x$Zn$_{1-x}$O: Using the hybrid exchange-correlation functional within the\ndensity-functional theory, we have systematically investigated the structural\nand electronic properties of MO (M = Be, Mg, Ca, Sr, Ba, Zn, Cd) in binary\nrocksalt (B1), zincblende (B3) and wurtzite (B4) phases, including the\nstructural parameters, bulk moduli, band gaps and deformation potentials. Our\nresults agree well with the experimental data and other theoretical results,\nand give a better understanding of the relationship between the geometric and\nelectronic structure. After calculating the band alignment, we find that in\nboth the B1 and B3 structures, the valence band maximum (VBM) has an obvious\ndecrease from BeO to MgO to CaO, then it goes up from SrO to BaO to ZnO to CdO.\nMoreover, the properties of the ternary alloys M$_x$Zn$_{1-x}$O were studied\nthrough the application of the special quasirandom structure method. The\ncritical value of the ZnO composition for the transition from the B3 structure\nto the B1 structure gradually increases from (Ca, Zn)O to (Mg, Zn)O to (Sr,\nZn)O to (Ba, Zn)O to (Cd, Zn)O, indicating that (Ca, Zn)O can exist in the B3\nstructure with the lowest ZnO composition. These results provide a good\nguideline for the accessible phase space in these alloy systems."
    },
    {
        "anchor": "Microscopic modeling of a spin crossover transition: In spin crossover materials, an abrupt phase transition between a low spin\nstate and a high spin state can be driven by temperature, pressure or by light\nirradiation. Of a special relevance are Fe(II) based coordination polymers\nwhere, in contrast to molecular systems, the phase transition between a spin\nS=0 and a spin S=2 state shows a pronounced hysteresis which is desirable for\ntechnical applications. A satisfactory microscopic explanation of this large\ncooperative phenomenon has been sought for a long time. The lack of X-ray data\nhas been one of the reasons for the absence of microscopic studies. In this\nwork, we present an efficient route to prepare reliable model structures and\nwithin an ab initio density functional theory analysis and effective model\nconsiderations we show that in polymeric spin crossover compounds magnetic\nexchange between high spin Fe(II) centers is as important as elastic couplings\nfor understanding the phase transition. We discuss the relevance of these\ninteractions for the cooperative behavior in these materials.",
        "positive": "Electronic, magnetic and transport properties of full and half-metallic\n  thin film Heusler alloys: The electronic and magnetic bulk properties of half-metallic Heusler alloys\nsuch as Co$_{2}$FeSi, Co$_{2}$FeAl, Co$_{2}$MnSi and Co$_{2}$MnAl are\ninvestigated by means of {\\em ab initio} calculations in combination with Monte\nCarlo simulations. The electronic structure is analyzed using the plane wave\ncode Quantum Espresso and magnetic exchange interactions are determined using\nthe KKR method. From the magnetic exchange interactions the Curie temperature\nis obtained via Monte Carlo simulations. In addition, electronic transport\nproperties of the trilayer systems consisting of two semi-infinite platinum\nleads and a Heusler layer in between are obtained from the fully relativistic\nKKR method by employing the Kubo-Greenwood formalism. The focus is on\nthermoelectric properties, namely the Seebeck effect and its spin dependence.\nIt turns out that already thin Heusler layers provide highly polarized currents\nwithin the systems. This is attributed to the recovery of half-metallicity with\nincreasing thickness. The absence of electronic states of the spin down\nelectrons around the Fermi level suppresses the contribution of this spin\nchannel to the total conductivity. This strongly influences the thermoelectric\nproperties of such systems and results in polarized thermoelectric currents."
    },
    {
        "anchor": "Surface and in-depth structural changes in nuclear graphite irradiated\n  with noble gases described with Raman imaging: 4th Generation high-temperature gas-cooled nuclear reactors (HTGR) are\nregarded as possible sources of industrial heat in Poland and Europe, allowing\nfor a substantial reduction of the dependency on gas and coal import. It is\nmainly due to their safety of use, reliability and economy in a current\nenergetic crisis. In this work, graphite, as a primary construction material\nand neutron moderator in HTGR, was evaluated before and after ion irradiation\nsince its properties depend on the material's structure and purity. Commercial\ngraphite materials (IG-110, NBG-17) and the laboratory's in-home material were\nchosen for the exemplary samples. The structural damage in HTGR was simulated\nwith energetic Ar+ and He+ ions with fluencies from 1E12 to 2E17 ion/cm2. Raman\nimaging was chosen to assess radiation damage build-up: the crystallites'\nevolution, occurrence and types of defects. The recorded evolution showed\nstronger disordering of the material with heavier Ar+ ions than with He+.",
        "positive": "Evidence for mechanical softening-hardening dual anomaly in transition\n  metals from shock compressed vanadium: Solid usually becomes harder and tougher under compression, and turns softer\nat elevated temperature. Recently, compression-induced softening and\nheating-induced hardening (CISHIH) dual anomaly was predicted in group VB\nelements such as vanadium. Here, the evidence for this counterintuitive\nphenomenon is reported. By using accurate high-temperature high-pressure sound\nvelocities measured at Hugoniot states generated by shock-waves, together with\nfirst-principles calculations, we observe not only the prominent\ncompression-induced sound velocity reduction, but also strong heating-induced\nsound velocity enhancement, in shocked vanadium. The former corresponds to the\nsoftening in shear modulus by compression, whereas the latter reflects the\nreverse hardening by heat. These experiments also unveil another anomaly in\nYoung's modulus that wasn't reported before. Based on the experimental and\ntheoretical data, we infer that vanadium might transition from BCC into two\ndifferent rhombohedral (RH1 and RH2) phases at about 79GPa and 116GPa along the\nHugoniot, respectively, which implies a dramatic difference in static and\ndynamic loading, as well as the significance of deviatoric stress and\nrate-relevant effects in high-pressure phase transition dynamics."
    },
    {
        "anchor": "Electronic structure study of YNbTiO$_6$ vs. CaNb$_2$O$_6$ with U, Pu\n  and minor actinide substitutions using compound-tunable embedding potential\n  method: The compound-tunable embedding potential (CTEP) method is applied to study\nactinide substitutions in the niobate crystals YNbTiO$_6$ and CaNb$_2$O$_6$.\nTwo one-center clusters centered on Ca and Y are built and 20 substitutions of\nCa and Y with U, Np, Pu, Am, and Cm in four different oxidation states were\nmade for each cluster. Geometry relaxation is performed for each resulting\nstructure, and electronic properties are analyzed by evaluating the spin\ndensity distribution and X-ray emission spectra chemical shifts. Though the\nstudied embedded clusters with actinides having the same oxidation state are\nfound in general to yield similar local structure distortions, for Am and Cm in\nhigh \"starting\" oxidation states the electron transfer from the environment was\nfound, resulting in decrease of their oxidation states, while for \"starting\"\nU$^{\\rm III}$ state the electron transfer goes in the opposite direction,\nresulting in increase of its oxidation state to U$^{\\rm IV}$.\n  The U substitutions are additionally studied with the use of multi-center\nmodels, which can provide both more structural and electronic relaxation and\nalso include charge-compensating vacancies. For \"starting\" U$^{\\rm VI}$ case,\nthe decrease in oxidation state similar to that of Am$^{\\rm VI}$ and Cm$^{\\rm\nVI}$ in one-center clusters is observed in our calculations but in a different\nway.\n  Since the really synthesized YNbTiO$_6$ structures can not be considered as\nperfect (periodic) crystals because the Nb and Ti atoms are statistically\ndistributed within them occupying the same Wyckoff positions, different Ti\n$\\leftrightarrow$ Nb substitutions are studied and corresponding structural\nchanges are estimated.",
        "positive": "Fluctuating surface-current formulation of radiative heat transfer for\n  arbitrary geometries: We describe a fluctuating surface-current formulation of radiative heat\ntransfer, applicable to arbitrary geometries, that directly exploits standard,\nefficient, and sophisticated techniques from the boundary-element method. We\nvalidate as well as extend previous results for spheres and cylinders, and also\ncompute the heat transfer in a more complicated geometry consisting of two\ninterlocked rings. Finally, we demonstrate that the method can be readily\nadapted to compute the spatial distribution of heat flux on the surface of the\ninteracting bodies."
    },
    {
        "anchor": "Non-singular dislocation loops in gradient elasticity: Using gradient elasticity, we give in this Letter the non-singular fields\nproduced by arbitrary dislocation loops in isotropic media. We present the\n`modified' Mura, Peach-Koehler and Burgers formulae in the framework of\ngradient elasticity theory.",
        "positive": "Magnetization reversal in exchange-spring bilayer system under\n  circularly polarized microwave field: Microwave assisted magnetization reversal are studied in the bulk bilayer\nexchange coupled system. We investigate the nonlinear magnetization reversal\ndynamics in a perpendicular exchange spring media using Landau-Lifshitz\nequation. In the limit of the infinite thickness of the system, the propagation\nfield leads the reversal of the system. The reduction of the switching field\nand the magnetization profile in the extended system are studied numerically.\nThe possibility to study the dynamics analytically is discussed and an\napproximation where two P-modes are coupled by an interaction field is\npresented. The ansatz used for the interaction field is validated by comparison\nwith the numerical results. This approach is shown to be equivalent to two\nexchange coupled macrospins."
    },
    {
        "anchor": "Excitation Pathways in Resonant Inelastic X-Ray Scattering of Solids: We present a novel derivation of resonant inelastic x-ray scattering (RIXS)\nwhich yields an expression for the RIXS cross section in terms of emission\npathways between intermediate and final many-body states. Thereby electron-hole\ninteractions are accounted for, as obtained from full diagonalization of the\nBethe-Salpeter equation within an all-electron first-principles framework. We\ndemonstrate our approach with the emission spectra of the fluorine K edge in\nLiF, and provide an in-depth analysis of the pathways that determine the\nspectral shape. Excitoninc effects are shown to play a crucial role in both the\nvalence and core regime.",
        "positive": "Quasi-1D graphene superlattices formed on high index surfaces: We report preparation of large area quasi-1D monolayer graphene superlattices\non a prototypical high index surface Cu(410)-O and characterization by Raman\nspectroscopy, Auger electron spectroscopy (AES), low energy electron\ndiffraction (LEED), scanning tunneling microscopy (STM) and scanning tunneling\nspectroscopy (STS). The periodically stepped substrate gives a 1D modulation to\ngraphene, forming a superlattice of the same super-periodicity. Consequently\nthe moire pattern is also quasi-1D, with a different periodicity. Scanning\ntunneling spectroscopy measurements revealed new Dirac points formed at the\nsuperlattice Brillouin zone boundary as predicted by theories."
    },
    {
        "anchor": "Pulsed Low-Field Electrically Detected Magnetic Resonance: We present pulsed electrically detected magnetic resonance (EDMR)\nmeasurements at low magnetic fields using posphorus-doped silicon with natural\nisotope composition as a model system. Our measurements show that pulsed EDMR\nexperiments, well established at X-band frequencies (10 GHz), such as coherent\nspin rotations, Hahn echoes, and measurements of parallel and antiparallel spin\npair life times are also feasible at frequencies in the MHz regime. We find\nthat the Rabi frequency of the coupled 31P electron-nuclear spin system scales\nwith the magnetic field as predicted by the spin Hamiltonian, while the\nmeasured spin coherence and recombination times do not strongly depend on the\nmagnetic field in the region investigated. The usefulness of pulsed low-field\nEDMR for measurements of small hyperfine interactions is demonstrated by\nelectron spin echo envelope modulation measurements of the Pb0 dangling-bond\nstate at the Si/SiO2 interface. A pronounced modulation with a frequency at the\nfree Larmor frequency of hydrogen nuclei was observed for radio frequencies\nbetween 38 MHz and 400 MHz, attributed to the nuclear magnetic resonance of\nhydrogen in an adsorbed layer of water This demonstrates the high sensitivity\nof low-field EDMR also for spins not directly participating in the\nspin-dependent transport investigated.",
        "positive": "Advancing carrier transport models for InAs/GaSb type-II superlattice\n  MWIR photodetectors: In order to provide the best possible performance, modern infrared\nphotodetector designs necessitate extremely precise modeling of the\nsuperlattice absorber region. We advance the Rode's method for the Boltzmann\ntransport equation in conjunction with the $\\bf k.p$ band structure and the\nenvelope function approximation for a detailed computation of the carrier\nmobility and conductivity of layered type-II superlattice structures, using\nwhich, we unravel two crucial insights. First, the significance of both elastic\nand inelastic scattering mechanisms, particularly the influence of the\ninterface roughness and polar optical phonon scattering mechanisms in\ntechnologically relevant superlattice structures. Second, that the\nstructure-specific Hall mobility and Hall scattering factor reveals that\ntemperature and carrier concentrations significantly affect the Hall scattering\nfactor, which deviates significantly from unity even for small magnetic fields.\nThis reinforces the caution that should be exercised when employing the Hall\nscattering factor in experimental estimations of drift mobilities and carrier\nconcentrations. Our research hence offers a comprehensive microscopic\nunderstanding of carrier dynamics in such technologically relevant\nsuperlattices. Our models also provide highly accurate and precise transport\nparameters beyond the relaxation time approximation and thereby paving the way\nto develop physics-based device modules for mid-wavelength infrared\nphotodetectors."
    },
    {
        "anchor": "Thermal diffusion by Brownian motion induced fluid stress: The Ludwig-Soret effect, the migration of a species due to a temperature\ngradient, has been extensively studied without a complete picture of its cause\nemerging. Here we investigate the dynamics of DNA and spherical particles sub\njected to a thermal gradient using a combination of Brownian dynamics and the\nlattice Boltzmann method. We observe that the DNA molecules will migrate to\ncolder regions of the channel, an observation also made in the experiments of\nDuhr, et al[1]. In fact, the thermal diffusion coefficient found agrees\nquantitatively with the experimental value. We also observe that the thermal\ndiffusion coefficient decreases as the radius of the studied spherical\nparticles increases. Furthermore, we observe that the thermal\nfluctuations-fluid momentum flux coupling induces a gradient in the stress\nwhich leads to thermal migration in both systems.",
        "positive": "Electronic properties of twisted multilayer graphene: Twisted bilayer graphene displays many fascinating properties that can be\ntuned by varying the relative angle (also called twist angle) between its\nmonolayers. As a remarkable feature, both the electronic flat bands and the\ncorresponding strong electron localization have been obtained at a specific\n\"magic\" angle ($\\sim 1.1^{\\circ}$), leading to the observation of several\nstrongly correlated electronic phenomena. Such a discovery has hence inspired\nthe creation of a novel research field called twistronics, i.e., aiming to\nexplore novel physical properties in vertically stacked 2D structures when\ntuning the twist angle between the related layers. In this paper, a\ncomprehensive and systematic study related to the electronic properties of\ntwisted multilayer graphene (TMG) is presented based on atomistic calculations.\nThe dependence of both the global and the local electronic quantities on the\ntwist angle and on the stacking configuration are analyzed, fully taking into\naccount atomic reconstruction effects. Consequently, the correlation between\nstructural and electronic properties are clarified, thereby highlighting the\nshared characteristics and differences between various TMG systems as well as\nproviding a comprehensive and essential overview. On the basis of these\ninvestigations, possibilities to tune the electronic properties are discussed,\nallowing for further developments in the field of twistronics."
    },
    {
        "anchor": "Theoretical and Experimental Study of LiBH4-LiBr Phase Diagram: Because substitutions of BH4- anion with Br can stabilize the hexagonal\nstructure of the LiBH4 at room temperature, leading to a high Li-ion\nconductivity, its thermodynamic stability has been investigated in this work.\nThe binary LiBH4-LiBr system has been explored by means of X-ray diffraction\nand differential scanning calorimetry, combined with an assessment of\nthermodynamic properties. The monophasic zone of the hexagonal Li(BH4)1-x(Br)x\nsolid solution has been defined from x=0.30 to x=0.55 at room temperature.\nSolubility limits have been determined by in-situ X-ray diffraction at various\ntemperatures. For the formation of the h-Li(BH4)0.6(Br)0.4 solid solution, a\nvalue of the enthalpy of mixing has been determined experimentally equal to 1.0\nkJ/mol. In addition, the enthalpy of melting has been measured for various\ncompositions. Lattice stabilities of LiBH4 and LiBr have been determined by ab\ninitio calculations, using CRYSTAL and VASP codes. Combining results of\nexperiments and theoretical calculations, the LiBH4-LiBr phase diagram has been\ndetermined in all composition and temperature range by the CALPHAD method.",
        "positive": "Laser induced ultrafast Gd 4f spin dynamics in Co100-xGdx alloys by\n  means of time-resolved XMCD: We have studied the laser induced ultrafast quenching of Gd 4f magnetic order\nin ferrimagnetic Co100-xGdx alloys to highlight the role of the inter-atomic\nexchange coupling. We have taken advantage of the ultrashort soft X-ray pulses\ndeliver by the femtoslicing beamline at the BESSY II synchrotron radiation\nsource at the Helmholtz-Zentrum Berlin to perform element- and time-resolved\nX-ray Magnetic Circular Dichroism spectroscopy.Our results show that the laser\ninduced quenching of Gd 4f magnetic order occurs on very different time-scales\nfor the Co72Gd28, the Co77Gd23 and the Co79Gd21 alloys. Most of the magnetic\nmoment losses occur within the first picosecond (ps) while the electron\ndistribution is strongly out of equilibrium. After the equilibration of the\nelectrons and lattice temperatures (t > 1 ps), the magnetic losses occur on\nslower rates that depend on the alloy composition: increasing the Co\ncomposition speeds up the demagnetization of Gd 4f sublattice. The strength of\nthe inter-atomic exchange coupling which depends on composition, determines the\nefficiency of the angular momentum flow from the Gd 4f spin towards the\nlattice. Our results are in qualitative agreements with the predictions of the\nmicroscopic three temperatures model for ferrimagnetic alloys."
    },
    {
        "anchor": "On the definition of chirality and enantioselective fields: In solid state physics, any symmetry breaking is known to be associated with\nemergence of an order parameter. However, the order parameter for molecular and\ncrystal chirality, which is a consequence of parity and mirror symmetry\nbreaking, has not been known since its discovery. In this article, the authors\nshow that the order parameter for chirality can be defined by electric toroidal\nmonopole G_0. By this definition, one becomes able to discuss external filed\nthat can distinguish two different enantiomers only by physical fields. In\naddition, dynamics and fluctuations of the order parameter G_0 can be\ndiscussed, with which one can obtain fruitful insights on a spin filtering\neffect called CISS (Chirality Induced Spin Selectivity). Emergence of\ntime-reversal-odd dipole M_z by time propagation of G_0 quantities is discussed\nto explain the enantioselective effect (chiral resolution) at a ferromagnetic\nsurface.",
        "positive": "Ab initio calculations of mean free paths and stopping powers: A method is presented for first-principles calculations of inelastic mean\nfree paths and stopping powers in condensed matter over a broad energy range.\nThe method is based on {\\it ab initio} calculations of the dielectric function\nin the long wavelength limit using a real-space Green's function formalism,\ntogether with extensions to finite momentum transfer. From these results we\nobtain the loss function and related quantities such as optical-oscillator\nstrengths and mean excitation energies. From a many-pole representation of the\ndielectric function we then obtain the electron self-energy and inelastic mean\nfree paths (IMFP). Finally using our calculated dielectric function and the\noptical-data model of Fern\\'andez-Varea {\\it et al}., we obtain collision\nstopping powers (CSP) and penetration ranges. The results are consistent with\nsemi-empirical approaches and with experiment."
    },
    {
        "anchor": "Mechanism of N\u00e9el order switching in antiferromagnetic thin films\n  revealed by magnetotransport and direct imaging: We probe the current-induced magnetic switching of insulating\nantiferromagnet/heavy metals systems, by electrical spin Hall magnetoresistance\nmeasurements and direct imaging, identifying a reversal occurring by domain\nwall (DW) motion. We observe switching of more than one third of the\nantiferromagnetic domains by the application of current pulses. Our data reveal\ntwo different magnetic switching mechanisms leading together to an efficient\nswitching, namely the spin-current induced effective magnetic anisotropy\nvariation and the action of the spin torque on the DWs.",
        "positive": "Direct measurement of coherent subterahertz acoustic phonons mean free\n  path in GaAs: Phonon mean free path is generally inferred from the measurement of thermal\nconductivity and we are still lacking precise information on this quantity.\nRecent advances in the field of high frequency phonons transduction using\nsemiconductor superlattices give the opportunity to fill this gap. We present\nexperimental results on the attenuation of longitudinal acoustic phonons in\nGaAs in the frequency and temperature ranges 0.2-1THz and 10-80K respectively.\nSurprisingly, we observe a plateau, in the frequency dependence of the\nattenuation, above 0.4THz, that we ascribe to a breakdown of Herring processes."
    },
    {
        "anchor": "Ab Initio Structural Energetics of Beta-Si3N4 Surfaces: Motivated by recent electron microscopy studies on the Si3N4/rare-earth oxide\ninterfaces, the atomic and electronic structures of bare beta-Si3N4 surfaces\nare investigated from first principles. The equilibrium shape of a Si3N4\ncrystal is found to have a hexagonal cross section and a faceted dome-like base\nin agreement with experimental observations. The large atomic relaxations on\nthe prismatic planes are driven by the tendency of Si to saturate its dangling\nbonds, which gives rise to resonant-bond configurations or planar sp^2-type\nbonding. We predict three bare surfaces with lower energies than the open-ring\n(10-10) surface observed at the interface, which indicate that\nnon-stoichiometry and the presence of the rare-earth oxide play crucial roles\nin determining the termination of the Si3N4 matrix grains.",
        "positive": "Epitaxial Growth of Large Area Single-Crystalline Few-Layer MoS2 with\n  Room Temperature Mobility of 192 cm2V-1s-1: We report on the vapor-solid growth of single crystalline few-layer MoS2\nfilms on (0001)-oriented sapphire with excellent structural and electrical\nproperties over centimeter length scale. High-resolution X-ray diffraction\nscans indicated that the films had good out-of-plane ordering and epitaxial\nregistry. A carrier density of ~2 x 1011 cm-2 and a room temperature mobility\nof 192 cm2/Vs were extracted from space-charge limited transport regime in the\nfilms. The electron mobility was found to exhibit in-plane anisotropy with a\nratio of ~ 1.8. Theoretical estimates of the temperature-dependent electron\nmobility including optical phonon, acoustic deformation potential and remote\nionized impurity scattering were found to satisfactorily match the measured\ndata. The synthesis approach reported here demonstrates the feasibility of\ndevice quality few-layer MoS2 films with excellent uniformity and high quality."
    },
    {
        "anchor": "Spontaneous Polarisation Build up in a Room Temperature Polariton Laser: We observe the build up of strong (~50%) spontaneous vector polarisation in\nemission from a GaN-based polariton laser excited by short optical pulses at\nroom temperature. The Stokes vector of emitted light changes its orientation\nrandomly from one excitation pulse to another, so that the time-integrated\npolarisation remains zero. This behaviour is completely different to any\nprevious laser. We interpret this observation in terms of the spontaneous\nsymmetry breaking in a Bose-Einstein condensate of exciton-polaritons.",
        "positive": "Separation of the two-magnon scattering contribution to damping for the\n  determination of the spin mixing conductance: We present angle dependent measurements of the damping properties of\nepitaxial Fe layers with MgO, Al and Pt capping layers. Based on the\npreferential distribution of lattice defects following the crystal symmetry, we\nmake use of a model of the defect density to separate the contribution of\ntwo-magnon scattering to the damping from the isotropic contribution\noriginating in the spin pumping effect, the viscous Gilbert damping and the\nmagnetic proximity effect. The separation of the two-magnon contribution, which\ndepends strongly on the defect density, allows for the measurement of a value\nof the effective spin mixing conductance which is closer to the value\nexclusively due to spin pumping. The influence of the defect density for\nbilayers systems due to the different capping layers and to the unavoidable\nspread in defect density from sample to sample is thus removed. This shows the\npotential of studying spin pumping phenomena in fully ordered systems in which\nthis separation is possible, contrary to polycrystalline or amorphous metallic\nthin films."
    },
    {
        "anchor": "Defect properties of Sn- and Ge-doped ZnTe: Suitability for\n  intermediate-band solar cells: We investigate the electronic structure and defect properties of Sn- and Ge-\ndoped ZnTe by first-principles calculations within the DFT+$GW$ formalism. We\nfind that $(\\text{Sn}_\\text{Zn})$ and $(\\text{Ge}_\\text{Zn})$ introduce\nisolated energy levels deep in the band gap of ZnTe, derived from Sn-5s and\nGe-4s states, respectively. Moreover, the incorporation of Sn and Ge on the Zn\nsite is favored in p-type ZnTe, in both Zn-rich and Te-rich environments. The\noptical absorption spectra obtained by solving the Bethe-Salpeter equation\nreveals that sub-bandgap absorptance is greatly enhanced due to the formation\nof the intermediate band. Our results suggest that Sn- and Ge-doped ZnTe would\nbe a suitable material for the development of intermediate-band solar cells,\nwhich have the potential to achieve efficiencies beyond the single-junction\nlimit.",
        "positive": "Factors determining surface oxygen vacancy formation energy in ternary\n  spinel structure oxides with zinc: Spinel oxides are an important class of materials for heterogeneous catalysis\nincluding photocatalysis and electrocatalysis. The surface O vacancy formation\nenergy (EOvac) is a critical quantity on catalyst performance because the\nsurface of metal oxide catalysts often acts as reaction sites, for example, in\nthe Mars-van Krevelen mechanism. However, experimental evaluation of EOvac is\nvery challenging. We obtained the EOvac for (100), (110), and (111) surfaces of\nnormal zinc-based spinel oxides ZnAl2O4, ZnGa2O4, ZnIn2O4, ZnV2O4, ZnCr2O4,\nZnMn2O4, ZnFe2O4, and ZnCo2O4. The most stable surface is (100) for all\ncompounds. The smallest EOvac for a surface is the largest in the (100) surface\nexcept for ZnCo2O4. For (100) and (110) surfaces, there is a good correlation,\nover all spinels, between the smallest EOvac for the surface and bulk formation\nenergy, while the ionization potential correlates well in (111) surfaces.\nMachine learning over EOvac of all surface sites in all orientations and all\ncompounds to find the important factors, or descriptors, that decide the EOvac\nrevealed that bulk and surface-dependent descriptors are the most important,\nnamely the bulk formation energy, a Boolean descriptor on whether the surface\nis (111), and the ionization potential, followed by geometrical descriptors\nthat are different in each O site."
    },
    {
        "anchor": "Molecular Dynamics Simulation of Plasma Surface Interaction: New interlayer intermolecular potential model was proposed and it represented\n``ABAB'' staking of graphite. Hydrogen atom sputtering on graphite surface was\ninvestigated using molecular dynamics simulation. In the initial short time\nperiod, maintaining the flat structure of graphenes, hydrogen atoms brought\nabout the difference interaction process in each incident energy. The first\ngraphene often adsorbed 5 eV hydrogen atoms and reflected almost all of 15 eV\nhydrogen atoms. The hydrogen atoms which were injected at 30 eV penetrated into\nthe inside of the graphite surface and were adsorbed between interlayer. The\ndesorption of C2H2 on the clear graphite surface was observed in only the case\nincident at 5 eV. The animation of the MD simulation and radial distribution\nfunction indicated that the graphenes were peeled off one by one at regular\ninterval. In common to the incident energy, the yielded molecules often had\nchain structures terminated by hydrogen atoms. The erosion yield increased\ncompared with the case of no interlayer intermolecular force.",
        "positive": "Voltage-dependent reconstruction of layered Bi$_2$WO$_6$ and\n  Bi$_2$MoO$_6$ photocatalysts and its influence on charge separation for water\n  splitting: We study the surface stability of the layered bismuth-oxide Bi$_2$WO$_6$ and\nBi$_2$MoO$_6$ photocatalysts, which belong to the series of Aurivillius\n(Bi$_2$A$_{n-1}$B$_{n}$O$_{3n+3}$) perovskites and have been proposed as\nefficient visible-light absorbers, due to favorable electronic hybridization\ninduced by the Bi 6s and 6p orbitals. We present a Newton--Raphson optimization\nof the charge distribution at the semiconductor--solution interface using the\nself-consistent continuum solvation (SCCS) model to describe the influence of\nthe aqueous environment. Our analysis provides a description of the charged\ninterface under controlled pH and applied voltage, and offers a molecular\ninterpretation of the competing structural and electrical factors that underlie\nthe facet-dependent photocatalytic activity of layered\nBi$_2$A$_{n-1}$B$_{n}$O$_{3n+3}$ compounds."
    },
    {
        "anchor": "Critical enhancement of thermopower in a chemically tuned polar\n  semimetal MoTe$_{\\bf 2}$: Ferroelectrics with spontaneous electric polarization play an essential role\nin today's device engineering, such as capacitors and memories. Their physical\nproperties are further enriched by suppressing the long-range polar order, as\nis exemplified by quantum paraelectrics with giant piezoelectric and dielectric\nresponses at low temperatures. Likewise in metals, a polar lattice distortion\nhas been theoretically predicted to give rise to various unusual physical\nproperties. So far, however, a \"ferroelectric\"-like transition in metals has\nseldom been controlled and hence its possible impacts on transport phenomena\nremain unexplored. Here we report the discovery of anomalous enhancement of\nthermopower near the critical region between the polar and nonpolar metallic\nphases in 1T'-Mo$_{1-x}$Nb$_{x}$Te$_2$ with a chemically tunable polar\ntransition. It is unveiled from the first-principles calculations and\nmagnetotransport measurements that charge transport with strongly\nenergy-dependent scattering rate critically evolves towards the boundary to the\nnonpolar phase, resulting in large cryogenic thermopower. Such a significant\ninfluence of the structural instability on transport phenomena might arise from\nthe fluctuating or heterogeneous polar metallic states, which would pave a\nnovel route to improving thermoelectric efficiency.",
        "positive": "Excitonic Stark effect in MoS$_2$ monolayers: We theoretically investigate excitons in MoS$_2$ monolayers in an applied\nin-plane electric field. Tight-binding and Bethe-Salpeter equation calculations\npredict a quadratic Stark shift, of the order of a few meV for fields of 10\nV/$\\mu$m, in the linear absorption spectra. The spectral weight of the main\nexciton peaks decreases by a few percent with an increasing electric field due\nto the exciton field ionization into free carriers as reflected in the exciton\nwave functions. Subpicosecond exciton decay lifetimes at fields of a few tens\nof V/$\\mu$m could be utilized in solar energy harvesting and photodetection. We\nfind simple scaling relations of the exciton binding, radius, and oscillator\nstrength with the dielectric environment and an electric field, which provides\na path to engineering the MoS$_2$ electro-optical response."
    },
    {
        "anchor": "Synthesis and characterization of HAp nanorods from a cationic\n  surfactant template method: Hydroxyapatite (HAp) [Ca10(PO4)6(OH)2] nanorods were synthesized using a\nsurfactant templating method, with cetyltrimethylammonium bromide (CTAB)\nmicelles acting as template for HAp growth. The effects of the sintering\ntemperature on the morphological and crystallographic characteristics and on\nchemical composition of the \"as-prepared\" structures are discussed. The\nexperimental results show that low heat-treatment temperatures are preferred in\norder to obtain high quality nanorods, with diameters ranging between 20 nm and\n50 nm. High heat-treatment temperatures enhance the thermal decomposition of\nHAp into other calcium phosphate compounds, and the sintering of particles into\nmicrometer ball-like structures. The stability of aqueous suspensions of HAp\nnanorods is also discussed.",
        "positive": "Single-step deposition of high-mobility graphene at reduced temperatures: Current methods of chemical vapor deposition (CVD) of graphene on copper are\ncomplicated by multiple processing steps and by high temperatures required in\nboth preparing the copper and inducing subsequent film growth. Here we\ndemonstrate a plasma-enhanced CVD chemistry that enables the entire process to\ntake place in a single step, at reduced temperatures (< 420 C), and in a matter\nof minutes. Growth on copper foils is found to nucleate from arrays of\nwell-aligned domains, and the ensuing films possess sub-nanometre smoothness,\nexcellent crystalline quality, low strain, few defects and room temperature\nelectrical mobility up to (6.0 +- 1.0) x 10^{4} cm^{2}V^{-1}s^{-1}, better than\nthat of large, single-crystalline graphene derived from thermal CVD growth.\nThese results indicate that elevated temperatures and crystalline substrates\nare not necessary for synthesizing high-quality graphene."
    },
    {
        "anchor": "Quantum point contact on graphite surface: The conductance through a quantum point contact created by a sharp and hard\nmetal tip on the graphite surface has features which to our knowledge have not\nbeen encountered so far in metal contacts or in nanowires. In this paper we\nfirst investigate these features which emerge from the strongly directional\nbonding and electronic structure of graphite, and provide a theoretical\nunderstanding for the electronic conduction through quantum point contacts. Our\nstudy involves the molecular-dynamics simulations to reveal the variation of\ninterlayer distances and atomic structure at the proximity of the contact that\nevolves by the tip pressing toward the surface. The effects of the elastic\ndeformation on the electronic structure, state density at the Fermi level, and\ncrystal potential are analyzed by performing self-consistent-field\npseudopotential calculations within the local-density approximation. It is\nfound that the metallicity of graphite increases under the uniaxial compressive\nstrain perpendicular to the basal plane. The quantum point contact is modeled\nby a constriction with a realistic potential. The conductance is calculated by\nrepresenting the current transporting states in Laue representation, and the\nvariation of conductance with the evolution of contact is explained by taking\nthe characteristic features of graphite into account. It is shown that the\nsequential puncturing of the layers characterizes the conductance.",
        "positive": "Data-driven analysis of the electronic-structure factors controlling the\n  work functions of perovskite oxides: Tuning the work functions of materials is of practical interest for\nmaximizing the performance of microelectronic and (photo)electrochemical\ndevices, as the efficiency of these systems depends on the ability to control\nelectronic levels at surfaces and across interfaces. Perovskites are promising\ncompounds to achieve such control. In this work, we examine the work functions\nof more than 1,000 perovskite oxide surfaces (ABO$_3$) by data-driven\n(machine-learning) analysis and identify the factors that determine their\nmagnitude. While the work functions of BO$_2$-terminated surfaces are sensitive\nto the energy of the hybridized oxygen p bands, the work functions of\nAO-terminated surfaces exhibit a much less trivial dependence with respect to\nthe filling of the d bands of the B-site atom and of its electronic affinity.\nThis study shows the utility of interpretable data-driven models in analyzing\nthe work functions of cubic perovskites from a limited number of\nelectronic-structure descriptors."
    },
    {
        "anchor": "Magnetic Phase Transition and Relaxation Effects in LiFePO4: We report the observation of para - antiferromagnetic transition at ~ 50 K in\nlithium iron phosphate, LiFePO4 through DC magnetization and M\\\"ossbauer\nspectroscopy. The Ferrous ion Fe2+ (3d6, 5D) in LiFePO4 exhibits relaxation\neffects with a relaxation frequency ~1.076 \\times 10(rise to 7) s-1 at 300 K.\nThe temperature dependence of the frequency suggests the origin of the\nrelaxation is spin-lattice type. The quadrupole splitting at low temperatures\nindicates the excited orbital states mix strongly to the orbital doublet ground\nstate via spin-orbit coupling. Modified molecular field model analysis yields a\nsaturation value for hyperfine field ~125 kOe. The anomaly in magnetization and\nM\\\"ossbauer parameters below 27 K may be ascribed to contribution of orbital\nangular momentum. The high value of the asymmetry parameter ({\\eta} ~ 0.8) of\nthe electric field gradient obtained in the antiferromagnetic regime indicates\na strongly distorted octahedral oxygen neighbourhood for the ferrous sites.",
        "positive": "Hydration of a side-chain-free n-type semiconducting ladder polymer\n  driven by electrochemical doping: We study the organic electrochemical transistors (OECTs) performance of the\nladder polymer, poly(benzimidazobenzophenanthroline) (BBL) in an attempt to\nbetter understand how an apparently hydrophobic side-chain-free polymer is able\nto operate as an OECT with favorable redox kinetics in an aqueous environment.\nWe examine two BBLs of different molecular masses from different sources. Both\nBBLs show significant film swelling during the initial reduction step. By\ncombining electrochemical quartz crystal microbalance (eQCM) gravimetry,\nin-operando atomic force microscopy (AFM), and both ex-situ and in-operando\ngrazing incidence wide-angle x-ray scattering (GIWAXS), we provide a detailed\nstructural picture of the electrochemical charge injection process in BBL in\nthe absence of any hydrophilic side-chains. Compared with ex-situ measurements,\nin-operando GIWAXS shows both more swelling upon electrochemical doping than\nhas previously been recognized, and less contraction upon dedoping. The data\nshow that BBL films undergo an irreversible hydration driven by the initial\nelectrochemical doping cycle with significant water retention and lamellar\nexpansion that persists across subsequent oxidation/reduction cycles. This\nswelling creates a hydrophilic environment that facilitates the subsequent fast\nhydrated ion transport in the absence of the hydrophilic side-chains used in\nmany other polymer systems. Due to its rigid ladder backbone and absence of\nhydrophilic side-chains, the primary BBL water uptake does not significantly\ndegrade the crystalline order, and the original dehydrated, unswelled state can\nbe recovered after drying. The combination of doping induced hydrophilicity and\nrobust crystalline order leads to efficient ionic transport and good stability."
    },
    {
        "anchor": "Hypoconstrained Jammed Packings of Nonspherical Hard Particles: Ellipses\n  and Ellipsoids: Continuing on recent computational and experimental work on jammed packings\nof hard ellipsoids [Donev et al., Science, vol. 303, 990-993] we consider\njamming in packings of smooth strictly convex nonspherical hard particles. We\nexplain why the isocounting conjecture, which states that for large disordered\njammed packings the average contact number per particle is twice the number of\ndegrees of freedom per particle (\\bar{Z}=2d_{f}), does not apply to\nnonspherical particles. We develop first- and second-order conditions for\njamming, and demonstrate that packings of nonspherical particles can be jammed\neven though they are hypoconstrained (\\bar{Z}<2d_{f}). We apply an algorithm\nusing these conditions to computer-generated hypoconstrained ellipsoid and\nellipse packings and demonstrate that our algorithm does produce jammed\npackings, even close to the sphere point. We also consider packings that are\nnearly jammed and draw connections to packings of deformable (but stiff)\nparticles. Finally, we consider the jamming conditions for nearly spherical\nparticles and explain quantitatively the behavior we observe in the vicinity of\nthe sphere point.",
        "positive": "Aromatic Hexazine [N6]4- Anion Revealed in the Complex Structure of the\n  High-Pressure Potassium Nitride K9N56: Recent high-pressure synthesis of pentazolates and subsequent stabilization\nof the aromatic [N5]- anion at atmospheric pressure had an immense impact on\nnitrogen chemistry. Here, we present the first synthesis of an aromatic\nhexazine [N6]4- anion realized in high-pressure potassium nitride K9N56 at 46\nand 61 GPa. The extremely complex structure of K9N56 was solved based on\nsynchrotron single-crystal X-ray diffraction and corroborated by density\nfunctional theory calculations. This result resolves a long-standing question\nof the aromatic hexazine stability and the possibility of its synthesis."
    },
    {
        "anchor": "Point defect in solids: Shear dominance of the far-field energy: It is shown that the elastic energy far from a point defect in an isotropic\nsolid is mainly shear elastic energy. The calculation, which is based on a\nstandard dipole expansion, shows that no matter how large or small the bulk\nmodulus is compared to the shear modulus, less than 10% of the distant point\ndefect energy is associated with volume changes.",
        "positive": "Electric-field switching magnetization and spin transfer in ultrathin\n  BiFeO3 film: First-principles density-functional theory calculations show switching\nmagnetization by 90 degree can be achieved in ultrathin BFO film by applying\nexternal electric-field. Up-spin carriers appear to the surface with positive\nfield while down-spin ones to the negative field surface, arising from the\nredistribution of Fe-t2g orbital. The half-metallic behavior of Fe-3d states in\nthe surface of R phase film makes it a promising candidate for AFM/FM bilayer\nheterostructure possessing electric-field tunable FM magnetization reversal and\nopens a new way towards designing spintronic multiferroics. The interface\nexchange-bias effect in this BFO/FM bilayer is mainly driven by the Fe-t2g\norbital reconstruction, as well as spin transferring and rearrangement."
    },
    {
        "anchor": "Nonvolatile ferroelectric control of topological states in 2D\n  heterostructures: Quantum spin Hall (QSH) insulator materials feature topologically protected\nedge states that can drastically reduce dissipation and are useful for the\nnext-generation electronics. However, the nonvolatile control of topological\nedge state is still a challenge. In this paper, based on first-principles\ncalculations, the switchable topological states are found in the van der Waals\n(vdW) heterostructures consisting of two dimensional (2D) Bi(111) bilayer (BL)\nand {\\alpha}-In2Se3 by reversing the electric polarization of the ferroelectric\n{\\alpha}-In2Se3. The topological switching results from the different charge\ntransfer associated with the two opposite polarization states of\n{\\alpha}-In2Se3. This new topological switching mechanism has the unique\nadvantages of being fully electrical as well as nonvolatile. Our finding\nprovides an unprecedented approach to realize ferroelectric control of\ntopological states in 2D materials, which will have great potential for\napplications in topological nanoscale electronics.",
        "positive": "Characterization of the Microstructure of Zirconolite-Based\n  Glass-Ceramics: December 1991 legislation in France has spurred research on enhanced\nseparation and conditioning or transmutation of long-lived radionuclides from\nhigh level radioactive wastes (HLW). In this field, we have studied\nzirconolite-based glass-ceramics in which the crystalline phase (zirconolite:\nCaZrTi2O7) aimed to preferentially incorporate minor actinides is embedded in a\nglassy calcium aluminosilicate matrix. At the laboratory scale, the\ncrystallization of the parent glass is carried out thanks to a two-step thermal\ntreatment: a nucleation stage followed by a growth stage. This paper presents\nthe evolution of the crystallization, followed by scanning electron microscopy\n(SEM) and X-ray diffraction (XRD), with the temperature of the crystal growth\nthermal treatment, in the range 950 degrees - 1350 degrees C."
    },
    {
        "anchor": "Intersubband polaritonics revisited: We revisited the intersubband polaritonics - the branch of mesoscopic physics\nhaving a huge potential for optoelectronic applications in the infrared and\nterahertz domains - and found that, contrary to the general opinion, the\nCoulomb interactions play crucial role in the processes of light-matter\ncoupling in the considered systems. Electron-electron and electron-hole\ninteractions radically change the nature of the elementary excitations in these\nsystems. We show that intersubband polaritons represent the result of the\ncoupling of a photonic mode with collective excitations, and not\nnon-interacting electron-hole pairs as it was supposed in the previous works on\nthe subject.",
        "positive": "Symmetry-Protected Ideal Type-II Weyl Phonons in CdTe: Nontrivial low-energy excitations of crystalline solids have insightfully\nstrengthened understanding of elementary particles in quantum field theory.\nUsually, topological quasiparticles are mainly focused on fermions in\ntopological semimetals. In this work, we alternatively show by first-principles\ncalculations and symmetry analysis that ideal type-II Weyl phonons are present\nin zinc-blende cadmium telluride (CdTe), a well-known II-VI semiconductor.\nImportantly, these type-II Weyl phonons originate from the inversion between\nthe longitudinal acoustic and transverse optical branches. Symmetry guarantees\nthe type-II Weyl points to lie along the high-symmetry lines at the boundaries\nof Brillouin zone even with breaking the inversion symmetry, exhibiting the\nrobustness of protected phonon features. The nontrivial phonon surface states\nand surface arcs projected on the semi-finite (001) and (111) surfaces are\ninvestigated. The phonon surface arcs connecting the Weyl points with opposite\nchirality, guaranteed to be very long, are clearly visible. This work not only\noffers a promising candidate for studying type-II Weyl phonons, but also\nprovides a route to realize symmetry-protected nontrivial phonons and related\napplications in realistic materials."
    },
    {
        "anchor": "Observation of Dirac surface states in the hexagonal PtBi2, a possible\n  origin of the linear magnetoresistance: The nonmagnetic compounds showing extremely large magnetoresistance are\nattracting a great deal of research interests due to their potential\napplications in the field of spintronics. PtBi$_2$ is one of such interesting\ncompounds showing large linear magnetoresistance (MR) in its both the hexagonal\nand pyrite crystal structure. We use angle-resolved photoelectron spectroscopy\n(ARPES) and density functional theory (DFT) calculations to understand the\nmechanism of liner MR observed in the hexagonal PtBi$_2$. Our results uncover\nfor the first time linear dispersive surface Dirac states at the\n$\\bar{\\Gamma}$-point, crossing Fermi level with node at a binding energy of\n$\\approx$ 900 meV, in addition to the previously reported Dirac states at the\n$\\bar{M}$-point in the same compound. We further notice from our dichroic\nmeasurements that these surface states show an asymmetric spectral intensity\nwhen measured with left and right circularly polarized light, hinting at a\nsubstantial spin polarization of the bands. Following these observations, we\nsuggest that the linear dispersive Dirac states at the $\\bar{\\Gamma}$ and\n$\\bar{M}$-points are likely to play a crucial role for the linear field\ndependent magnetoresistance recorded in this compound.",
        "positive": "Systematic Investigation of Anisotropic Magneto-Peltier Effect and\n  Anomalous Ettingshausen Effect in Ni Thin Films: The anisotropic magneto-Peltier effect (AMPE) and anomalous Ettingshausen\neffect (AEE) have been investigated in U-shaped Ni thin films of varying\nthickness and substrate by means of the lock-in thermography (LIT) method. We\nhave established a procedure to extract pure AMPE and AEE contributions,\nseparated from other thermoelectric effects, for ferromagnetic thin films. The\nmeasurements of the magnetic-field-angle $\\theta_{\\rm H}$ dependence of the LIT\nimages clearly show that the temperature modulation induced by the AMPE (AEE)\nin the Ni films varies with the $\\cos 2\\theta_{\\rm H}$ ($\\cos \\theta_{\\rm H}$)\npattern, confirming the symmetry of the AMPE (AEE). The systematic LIT\nmeasurements using various substrates show that the AMPE-induced temperature\nmodulation decreases with the increase in thermal conductivity of the\nsubstrates, whereas the AEE-induced temperature modulation is almost\nindependent of the thermal conductivity, indicating that the heat loss into the\nsubstrates plays an important role in determining the magnitude of the\nAMPE-induced temperature modulation in thin films. Our experimental results\nwere reproduced by numerical calculations based on a two-dimensional finite\nelement method. These findings provide a platform for investigating the AMPE\nand AEE in thin film devices."
    },
    {
        "anchor": "Lattice strain at c-Si surfaces: a density functional theory calculation: The measurement of the Avogadro constant by counting Si atoms is based on the\nassumption that Si balls of about 94 mm diameter have a perfect crystal\nstructure up to the outermost atom layers. This not the case because of the\nsurface relaxation and reconstruction, the possible presence of an amorphous\nlayer, and the oxidation process due to the interaction with the ambient. This\npaper gives the results of density functional calculations of the strain\ncomponents orthogonal to crystal surface in a number of configurations likely\nfound in real samples.",
        "positive": "Crater formation by fast ions: comparison of experiment with Molecular\n  Dynamics simulations: An incident fast ion in the electronic stopping regime produces a track of\nexcitations which can lead to particle ejection and cratering. Molecular\nDynamics simulations of the evolution of the deposited energy were used to\nstudy the resulting crater morphology as a function of the excitation density\nin a cylindrical track for large angle of incidence with respect to the surface\nnormal. Surprisingly, the overall behavior is shown to be similar to that seen\nin the experimental data for crater formation in polymers. However, the\nsimulations give greater insight into the cratering process. The threshold for\ncrater formation occurs when the excitation density approaches the cohesive\nenergy density, and a crater rim is formed at about six times that energy\ndensity. The crater length scales roughly as the square root of the electronic\nstopping power, and the crater width and depth seem to saturate for the largest\nenergy densities considered here. The number of ejected particles, the\nsputtering yield, is shown to be much smaller than simple estimates based on\ncrater size unless the full crater morphology is considered. Therefore, crater\nsize can not easily be used to estimate the sputtering yield."
    },
    {
        "anchor": "Probing the Dzyaloshinskii-Moriya interaction in CoFeB ultrathin films\n  using domain wall creep and Brillouin light spectroscopy: We have characterized the strength of the interfacial Dyzaloshinskii-Moriya\ninteraction (DMI) in ultrathin perpendicularly magnetized CoFeB/MgO films,\ngrown on different underlayers of W, TaN, and Hf, using two experimental\nmethods. First, we determined the effective DMI field from measurements of\nfield-driven domain wall motion in the creep regime, where applied in-plane\nmagnetic fields induce an anisotropy in the wall propagation that is correlated\nwith the DMI strength. Second, Brillouin light spectroscopy was employed to\nquantify the frequency non-reciprocity of spin waves in the CoFeB layers, which\nyielded an independent measurement of the DMI. By combining these results, we\nshow that DMI estimates from the different techniques only yield qualitative\nagreement, which suggests that open questions remain on the underlying models\nused to interpret these results.",
        "positive": "Analysis of Floquet formulation of time-dependent density-functional\n  theory: Floquet formulation of time-dependent density-functional theory is revisited\nin light of its recent criticism [Maitra and Burke, Chem. Phys. Lett. 359\n(2002), 237]. It is shown that Floquet theory is well founded and its criticism\nhas overlooked important points of both the Runge-Gross formalism and Floquet\nformulation itself. We substantiate our analysis by examples similar to that\nconsidered by Maitra and Burke."
    },
    {
        "anchor": "Strong Spin-Orbit Torque Induced by the Intrinsic Spin Hall Effect in\n  Cr1-xPtx: We report on a spin-orbit torque study of the spin current generation in\nCr1-xPtx alloy, using the light 3d ferromagnetic Co as the spin current\ndetector. We find that the dampinglike spin-orbit torque of Cr1-xPtx/Co\nbilayers can be enhanced by tuning the Cr concentration in the Cr1-xPtx layer,\nwith a maximal value of 0.31 at the optimal composition of Cr0.2Pt0.8. We find\nthat the spin current generation in the Cr1-xPtx alloy can be fully understood\nby the characteristic trade-off between the intrinsic spin Hall conductivity of\nPt and the carrier lifetime in the dirty limit. We find no evidence for the\nspin current generation by other mechanisms in this material, revealing that\nthe role of Cr is found to be simply the same as other metals and oxides in\nprevious studies. This work also establishes the low-resistivity Cr0.2Pt0.8 as\nan energy-efficient spin-orbit torque provider for magnetic memory and\ncomputing technologies.",
        "positive": "Electron-phonon coupling in metals at high electronic temperatures: Electron-phonon coupling, being one of the most important parameters\ngoverning the material evolution after ultrafast energy deposition, yet remains\nthe most unexplored one. In this work, we applied the dynamical coupling\napproach to calculate the nonadiabatic electron-ion energy exchange in\nnonequilibrium solids with the electronic temperature high above the atomic\none. It was implemented into the tight-binding molecular dynamics code, and\nused to study electron-phonon coupling in various elemental metals. The\ndeveloped approach is a universal scheme applicable to electronic temperatures\nup to a few electron-Volts, and to arbitrary atomic configuration and dynamics.\nWe demonstrate that the calculated electron-ion (electron-phonon) coupling\nparameter agrees well with the available experimental data in\nhigh-electronic-temperature regime, validating the model. The following\nmaterials are studied here - fcc metals: Al, Ca, Ni, Cu, Sr, Y, Zr, Rh, Pd, Ag,\nIr, Pt, Au, Pb; hcp metals: Mg, Sc, Ti, Co, Zn, Tc, Ru, Cd, Hf, Re, Os; bcc\nmetals: V, Cr, Fe, Nb, Mo, Ba, Ta, W; diamond cubic lattice metals: Sn;\nspecific cases of Ga, In, Mn, Te and Se; and additionally semimetal graphite\nand semiconductors Si and Ge. For many materials, we provide the first and so\nfar the only estimation of the electron-phonon coupling at elevated electron\ntemperatures, which can be used in various models simulating ultrafast energy\ndeposition in matter. We also discuss the dependence of the coupling parameter\non the atomic mass, temperature and density."
    },
    {
        "anchor": "Melting and crystallization of Sn, Bi and Pb nanoparticles in contact\n  with Al: The results of studies of supercooling upon crystallization value of Bi, Sn\nand Pb nanosized particles on the Al substrate and between the Al layers have\nbeen presented. It has been shown the efficiency of usage of layered film\nsystems for investigation of the limiting supercooling in particle-matrix\nsystems with an eutectic type of interaction between components. The obtained\nresults have been discussed and compared with literature data.\n  -----\n  Predstavleny rezultaty issledovanij pereohlazhdenij pri kristallizacii\nnanorazmernyh chastic Bi, Sn i Pb na Al podlozhke i mezhdu sloyami alyuminiya.\nPokazana effektivnost ispolzovaniya sloistyh plenochnyh sistem dlya\nissledovaniya predelnogo pereohlazhdeniya v sistemah chastica-matrica s\nevtekticheskim tipom vzaimodejstviya mezhdu komponentami. Poluchennye rezultaty\nobsuzhdeny i sopostavleny s literaturnymi dannymi.",
        "positive": "Negative refraction and superlensing in a 2D photonic crystal structure: We experimentally and theoretically studied a new left-handed (LH) structure\nbased on a photonic crystal (PC) with a negative refractive index. The\nstructure consists of triangular array of rectangular dielectric bars with\ndielectric constant 9.61. Experimental and theoretical results demonstrate the\nnegative refraction and the superlensing phenomena in the microwave regime. The\nresults show high transmission for our structure for a wide range of incident\nangles. Furthermore, surface termination within a specific cut of the structure\nexcite surface waves at the interface between air and PC and allow the\nreconstruction of evanescent waves for a better focus and better transmission.\nThe normalized average field intensity calculated in both the source and image\nplanes shows almost the same full width at half maximum for the source and the\nfocused beam."
    },
    {
        "anchor": "On the formation of metallic glass: The high cooling rate needed for preparing the metallic glass (MG) makes the\nnonequilibrium nature of glass formation more prominent and requires a better\nquenching technique than ever before. Here, we formulate the cooling process in\nan analytical way and figure out the determinants for cooling rate, and analyze\nthe crystallization time with consideration of phase diagram. Based on the\nreduced glass transition temperature, Trg, for measuring the glass-forming\nability (GFA), a more reasonable {\\Delta}Trg is proposed. Glass transition,\nespecially in ever glass whose ground state is of glass, is discussed in terms\nof thermodynamics for phase transition. A fundamental law concerning the\nchanging rate of entropy in a closed system is supposed to underlie the physics\nfor glass formation. These results may help understand the glass formation\nprincipally and develop new and robust MGs technically.",
        "positive": "Micro-Raman spectroscopy of ultrashort laser induced microexplosion\n  sites in silicon: Confined microexplosions induced in silicon by powerful ultrashort laser\npulses can lead to new Si phases. Some of these have not previously been\nobserved via near-equilibrium compression of silicon. In this study, confocal\nRaman micro-spectroscopy and Raman imaging of arrays of microexplosions have\nbeen conducted to search for Raman signatures of these novel allotropes of\nsilicon. A microexplosion is generated at the interface between a thick silicon\ndioxide confinement layer and underlying silicon. It is characterised by a void\nat the interface above a region of compressed silicon. Raman data show a rich\nassembly of silicon phases within the modified silicon. Residual stresses up to\n4.5 GPa in the modifications have been determined from the shift in the main\ndiamond-cubic Si Raman peak. The computed Raman spectra for a number of Si\nallotropes show reasonable agreement with the experimental spectra. Two\nstructurally similar tetragonal phases of silicon (the rhombohedral r8 and the\nbody-centred bc8) phases as well as recently identified bt8-Si are all highly\nlikely to be contained in Raman spectra from many laser-modified sites.\nAlthough the st12-Si phase, previously observed in our electron diffraction\nstudies of the highly compressively stressed laser-modified regions, was not\nreliably identified from Raman data, we suggest this could be due to the\npossible difference in residual stress level in the sites analysed by the\nelectron diffraction and Raman spectra. Several other unidentified Raman peaks\nwere observed, suggesting the presence of other unknown silicon phases. All of\nthese silicon phases are expected to have attractive semiconducting properties\nincluding narrow band gap that open up novel applications."
    },
    {
        "anchor": "On the breakdown of the simple Arrhenius law in the normal liquid state: It is common practice to discuss the temperature effect on molecular dynamics\nof glass formers above the melting temperature in terms of the Arrhenius law.\nUsing dielectric spectroscopy measurements of dc-conductivity and structural\nrelaxation time on the example of the typical glass former propylene carbonate,\nwe provide experimental evidence that this practice is not justified. Our\nconclusions are supported by employing thermodynamic density scaling and the\noccurrence of inflection points in isothermal dynamic data measured at elevated\npressure. Additionally, we propose a more suitable approach to describe the\ndynamics both above and below the inflection point based upon a modified MYEGA\nmodel.",
        "positive": "Prediction of a controllable Weyl semi-metallic phase in\n  inversion-asymmetric BiSb: Recent experimental realization of long sought Weyl fermions in non-magnetic\ncrystals has greatly motivated condensed matter physicists to search for\nmaterials supporting Weyl fermions. Weyl fermions appear to be very promising\nfor future electronics, often referred as Weyltronics. Here, by means of\nfirst-principle calculations, we report a stoichiometric crystal structure of\nBiSb with broken space-inversion symmetry. This structure is insulating in bulk\nand has non-trivial band topology. We observe a pressure driven Weyl\nsemi-metallic phase transition in this crystal structure. The obtained Weyl\nsemi-metallic phase exists in the 4.0 - 6.0 GPa pressure range. We find that a\ntotal 6 pairs of Weyl points, 6 monopoles and 6 antimonopoles, exist in the\nBrillouin zone. The Weyl points with opposite chirality are located at\ndifferent energy values yielding separate electron and hole Fermi-surfaces.\nAdditionally, the spin-texture of the bulk BiSb compound appears to be\nelectrically controllable when the interlink between pressure and an electric\nfield is exploited. This produces novel manipulable topological transport\nproperties in this system which are very promising for implementation of this\nkind of materials in next-generation Weyltronics and spintronic devices."
    },
    {
        "anchor": "Temperature Evolution of Sodium Nitrite Structure in a Restricted\n  Geometry: The NaNO$_{2}$ nanocomposite ferroelectric material in porous glass was\nstudied by neutron diffraction. For the first time the details of the crystal\nstructure including positions and anisotropic thermal parameters were\ndetermined for the solid material, embedded in a porous matrix, in ferro- and\nparaelectric phases. It is demonstrated that in the ferroelectric phase the\nstructure is consistent with bulk data but above transition temperature the\ngiant growth of amplitudes of thermal vibrations is observed, resulting in the\nformation of a \"premelted state\". Such a conclusion is in a good agreement with\nthe results of dielectric measurements published earlier.",
        "positive": "Analysis of Thermal Stresses in Solidification of Spherical SLM\n  Components: The majority of these machines fabricate from raw material in powder form\nusing a directed energy beam to create a local melt zone. Total hip replacement\nis recommended for people who have medical issues related to excessive wear of\nthe acetabular, osteoarthritis, accident or age. Researches have shown that\nlarge numbers of hip arthroplasties (where the articular surface of a\nmusculoskeletal joint is replaced), hip remodelling, or realignment are carried\nout annually and will increase in the next few decades. Manufacturing of\nacetabular shells by using AM is a promising and emerging method that has a\ngreat potential to improve public health. Lost wax casting or investment\ncasting is currently used to produce acetabular shells followed by lengthy and\ncomplex secondary processes such as machining and polishing. Living organs and\nmedical models have intricate 3D shapes that are challenging to identity in\nX-ray CT images. These images are used for preparing treatment plans to improve\nthe quality of the surgeries regarding waiting and surgery time per procedure\nand care regime. For instance, a limited number of hip replacement procedures\ncan be carried out on each acetabulum due to a decrease of bone thickness.\nRapid prototyping is a suitable treatment planning tool in complex cases to\nenhance the quality of surgical procedure and provide long-term stability that\ncan be used to customize the shape and size of the acetabular shell. In this\npaper, to analyse the manufacturing of a prosthetic acetabular shell, built-up\nlines resulting from a thermal stress flow and process stopping during the\nselective laser melting (SLM) AM process, with regarding Gibbs free energy,\ninterfacial energy, and equilibrium temperature will be discussed. Geometrical\nmeasurements showed 1.59% and 0.27% differences between the designed and\nmanufactured prototype for inside and outside diameter respectively."
    },
    {
        "anchor": "Magnetic fluctuations and spin-spirals in single-layer FeSe: The magnetic properties of monolayer FeSe films are investigated via\nfirst-principles spin-spiral calculations. Although the (pi,pi) collinear\nantiferromagnetic (CL-AFM) mode is lowest in energy, the spin-wave energy E(q)\n- which exhibits intrinsic non-Heisenberg behavior - is found to be extremely\nvery flat over a large region of the two-dimensional Brillouin zone centered at\nthe checkerboard antiferromagnetic (CB-AFM) q=0 configuration, giving rise to a\nsharp peak in the spin density of states. Considering the paramagnetic state as\nan incoherent average over spin-spiral states, we find that resulting\nelectronic band states around the Fermi level closely resemble the bands of the\nCB-AFM configuration - not the CL-AFM one - and thus providing a natural\nexplanation of the angle-resolved photoemission observations. The presence of\nthe SrTiO3(001) substrate, both with and without interfacial oxygen vacancies,\nis found to reduce the energy difference between the CB-AFM and CL-AFM states\nand hence enhancing the CB-AFM-like fluctuations.",
        "positive": "Piezoelectric-based apparatus for strain tuning: We report the design and construction of piezoelectric-based apparatus for\napplying continuously tuneable compressive and tensile strains to test samples.\nIt can be used across a wide temperature range, including cryogenic\ntemperatures. The achievable strain is large, so far up to 0.23% at cryogenic\ntemperatures. The apparatus is compact and compatible with a wide variety of\nexperimental probes. In addition, we present a method for mounting\nhigh-aspect-ratio samples in order to achieve high strain homogeneity."
    },
    {
        "anchor": "Study of the ferromagnetic quantum phase transition in\n  Ce$_{3-x}$Mg$_x$Co$_{9}$: The Ce$_{3-x}$Mg$_x$Co$_{9}$ system evolves from a Pauli paramagnetic ground\nstate for $x = 0$ to a ferromagnetic ground state for $x\\approx0.80$ in single\nphase, polycrystalline samples [Phys. Rev. Applied 9, 024023 (2018)]. In order\nto better understand this behavior, single crystalline samples of\nCe$_{3-x}$Mg$_x$Co$_{9}$ for \\textit{x} = 0.01, 0.16, 0.24, 0.35, 0.43 and 0.50\nwere grown using the flux growth technique, and electrical transport and\nmagnetic properties were studied. The \\textit{T}$_C$-\\textit{x} phase diagram\nwe infer shows that the system has a quantum phase transition near \\textit{x} =\n0.35, transforming to a ferromagnetic ground state.",
        "positive": "Single crystal growths and magnetic properties of hexagonal polar\n  semimetals RAuGe (R = Y, Gd-Tm, and Lu): We study structural and magnetic properties of rare-earth based semimetals\nRAuGe (R = Y, Gd-Tm, and Lu) using flux-grown single crystals. These compounds\nbelong to the noncentrosymmetric polar space group P63mc. We confirm the\nsystematic structural evolution at room temperature as a function of ionic\nradius of rare earths to clarify the isopointal crossover between two polar\nstructures: three-dimensional LiGaGe-type and quasi-two-dimensional\nNdPtSb-type. Magnetism shows a characteristic anisotropy in reasonable\nagreement with the crystal electric field (CEF) theory; the easy-plane-type\nanisotropy for R = Tb and Dy turns into the Ising-type anisotropy for R = Er\nand Tm. We evaluate the CEF parameters based on the Stevens operators to\nreasonably reproduce the temperature dependence of magnetic susceptibilities\nand specific heat for RAuGe (R = Tb-Tm). The estimated energy scale of the\nIsing gap (~ 11 meV) in TmAuGe is consistent with an excitation observed in an\ninelastic neutron scattering experiment. These findings suggest an opportunity\nfor interplay between conduction electrons and nontrivial spin structures in\nthe family of magnetic polar semimetals RAuGe."
    },
    {
        "anchor": "Investigation of Ultrathin Layers of Bis(phthalocyaninato)lutetium(III)\n  on Graphite: We present a comprehensive study of the adsorption of\nbis(phthalocyaninato)lutetium(III) (LuPc$_2$) on highly oriented pyrolytic\ngraphite(0001) (HOPG). The growth and self-assembly of the molecular layers as\nwell as the electronic structure has been investigated systematically using\nscanning tunnelling microscopy and scanning tunnelling spectroscopy combined\nwith density functional theory (DFT) calculations and molecular mechanics\nsimulations. We reveal that the adsorption of LuPc$_2$ leads to the formation\nof a square-like close-packed structure on the almost inert surface of HOPG,\nwhich is corroborated by simulations. Moreover, we observed a parallel\norientation of the LuPc$_2$ molecules in the first monolayer, whereas in\nsubsequent layers an increasing tilt out of the surface plane was found.\nTip-sample distance-dependent tunnelling spectroscopy measurements allowed us\nto detect a shift in the energy positions of the peaks assigned to the lowest\nunoccupied molecular orbital toward the Fermi energy with decreasing tip-sample\nseparation.",
        "positive": "Computational Synthesis of Substrates by Crystal Cleavage: The discovery of novel substrate materials has been dominated by trial and\nerror, opening the opportunity for a systematic search. To identify stable\ncrystal surfaces, we generate bonding networks for materials from the Materials\nProject database with one to five atoms in the primitive unit cell. For\nthree-dimensional crystals in this set, we systematically break up to three\nbonds in the bonding network of the primitive cell. Successful cleavage reduces\nthe bonding network to two periodic dimensions, creating a layer of the cleaved\ncrystal. We identify 4,693 unique cleavage surfaces across 2,133 bulk crystals,\n4,626 of which have a maximum Miller index of 1. To characterize the likelihood\nof cleavage and the thermodynamic stability of the cleaved surfaces, we create\nmonolayers of these surfaces and calculate the work of cleavage and the\npartially-relaxed surface energy using density functional theory to discover\n3,991 potential substrates, 2,307 of which do not contain f-valence electrons\nand 2,183 of which are derived from a bulk precursor with an entry in the\nInorganic Crystal Structure Database. Following, we identify distinct trends in\nthe work of cleavage of these layers and relate them to metallic and\ncovalent/ionic bonding of the three-dimensional precursor. We also assembled a\ndatabase of commercially available substrates and show that the database of\npredicted substrates significantly enhances the diversity and range of the\ndistribution of electronic properties and lattice parameters, providing\nopportunities for the epitaxial growth of many materials. We illustrate the\npotential impact of the substrate database by identifying several new epitaxial\nsubstrates for the transparent conductor BaSnO3, which exhibit low cleavage\nenergies and result in strains an order of magnitude lower than currently used\nsubstrates."
    },
    {
        "anchor": "Density-functional approach to the band gaps of finite and periodic\n  two-dimensional systems: We present an approach based on density-functional theory for the calculation\nof fundamental gaps of both finite and periodic two-dimensional (2D) electronic\nsystems. The computational cost of our approach is comparable to that of total\nenergy calculations performed via standard semi-local forms. We achieve this by\nreplacing the 2D local density approximation with a more sophisticated -- yet\ncomputationally simple -- orbital-dependent modeling of the exchange potential\nwithin the procedure by Guandalini et al. [Phys. Rev. B 99, 125140 (2019)]. We\nshowcase promising results for semiconductor 2D quantum dots and artificial\ngraphene systems, where the band structure can be tuned through, e.g., Kekul\\'e\ndistortion.",
        "positive": "Densest binary sphere packings and phase diagram : revisited: We revisit the densest binary sphere packings (DBSP) under the periodic\nboundary conditions and present an updated phase diagram, including newly found\n12 putative densest structures over the $x - \\alpha$ plane, where $x$ is the\nrelative concentration and $\\alpha$ is the radius ratio of the small and large\nspheres. To efficiently explore the DBSP, we develop an unbiased random search\napproach based on both the piling up method to generate initial structures in\nan unbiased way and the iterative balance method to optimize the volume of a\nunit cell while keeping the overlap of hard spheres minimized. With those two\nmethods, we have discovered 12 putative DBSP and thereby the phase diagram is\nupdated, while our results are consistent with those of the previous study\n[Hopkins et al., Phys. Rev. E 85, 021130 (2012)] with a small correction for\nthe case of 12 or fewer spheres in the unit cell. The 5 of the new 12 densest\npackings are discovered in the small radius range of $0.42 \\le \\alpha \\le 0.50$\nwhere several structures are competitive to each other with respect to packing\nfraction. Through the exhaustive search, diverse dense packings are discovered\nand accordingly we find that packing structures achieve high packing fractions\nby introducing distortion and/or combining a few local dense structural units.\nFurthermore, we investigate the correspondence of the DBSP with crystals based\non the space group. The result shows that many structural units in real\ncrystals, e.g., $\\mathrm{LaH_{10}}$ and $\\mathrm{SrGe_{2-\\delta}}$ being\nhigh-pressure phases, can be understood as DBSP. The correspondence implies\nthat the densest sphere packings can be used effectively as structural\nprototypes for searching complex crystal structures, especially for\nhigh-pressure phases."
    },
    {
        "anchor": "Mn$_m$Tc$_n$ nanoalloy clusters obey Vegard's law : A first principles\n  prediction: With a view to gain an understanding about the alloying tendency of\nbimetallic nano alloy clusters of isoelectronics constituents, we studied the\nstructural and mixing behaviors of Mn$_m$Tc$_n$ alloy clusters with $m+n =$13\nfor all possible compositions, using first principles electronic structure\ncalculations. Our study reports a favorable mixing tendency for the alloy\nclusters. The average bond lengths of the minimum energy structures show an\noverall linear variation with concentrations, indicating a Vegard's law like\nvariation for the nano alloy clusters, though the optimized structures undergo\na structural transition from a closed and compact structure for the Mn-rich\nalloy clusters to an open layered like structure for the Tc-rich alloy\nclusters. We figure out a continuous and smooth interplay between hybridization\nand magnetization properties of the alloy clusters, which plays a vital role\nfor the Vegard's law like variation in their average bond lengths.",
        "positive": "Strong asymmetry of microwave absorption by bi-layer conducting\n  ferromagnetic films in the microstrip-line based broadband ferromagnetic\n  resonance: Peculiarities of ferromagnetic resonance response of conducting magnetic\nbi-layer films of nanometric thicknesses excited by microstrip microwave\ntransducers have been studied theoretically. Strong asymmetry of the response\nhas been found. Depending on the order of layers with respect to the transducer\neither the first higher-order standing spin wave mode, or the fundamental mode\nshows the largest response.\n  Film conductivity and lowered symmetry of microwave fields of such\ntransducers are responsible for this behavior. Amplitude of which mode is\nlarger also depends on the driving frequency. This effect is explained as\nshielding of the asymmetric transducer field by eddy currents in the films.\nThis shielding remains very efficient for films with thicknesses well below the\nmicrowave skin depth. This effect may be useful for studying buried magnetic\ninterfaces and should be accounted for in future development of broadband\ninductive ferromagnetic resonance methods."
    },
    {
        "anchor": "Sputtering power effects on the electrochromic properties of NiO films: The effect of sputtering power ($P$=60 W-180 W) on the electrochromic\nproperties of nickel oxide films deposited on ITO-coated glass substrates by\nthe RF magnetron sputtering technique was investigated. Crystalline structure\nand morphology were assessed by X-ray diffraction (XRD) and scanning electron\nmicroscopy (SEM), respectively. The effect of sputtering power on\nelectrochromism of the samples was evaluated with cyclic voltammetry and\nchronoamperometry. We used LiClO$_4$ in propilene carbonate solution for Li\ninsertion/extraction. The chemical composition of the samples before and after\nLi intercalation was analyzed by X-ray photoelectron spectroscopy (XPS). We\nobserved the cubic phase of NiO with sputtering power mainly affecting\ncrystallinity and grain size. These in turn affect the electrochromic\nproperties. Coloration efficiency reduces from 24.4 cm$^{2}$/C to (15.4, 13.7.\n16.1) cm$^{2}$/C and the reversibility from 40% to 30% as sputtering power\nincreases from 60 W to 180 W. The impedance spectra indicates that ion\ndiffusion is larger for the film grown at 60 W and then goes down for the films\ndeposited at higher sputtering powers. XPS analysis reveals that higher values\nof $P$ promote the formation of nickel hydroxides on the film surface. As\nconsequence of changes in crystallinity and morphology, the presence of nickel\nhydroxides increases, showing that not only the electrochromic properties of\nthe samples are affected by the sputtering power but also their chemical\ncomposition.",
        "positive": "Femtosecond optical breakdown in silicon: We investigate photoinization, energy deposition, plasma formation and the\nultrafast optical breakdown in crystalline silicon irradiated by intense\nnear-infrared laser pulses with pulse duration $\\tau \\le $ 100 fs. The\noccurrence of high-intensity breakdown was established by the sudden increase\nof the absorbed laser energy inside the bulk, which corresponds to threshold\nenergy fluence $\\Phi_{th} > $ 1 J/cm$^2$. The optical breakdown is accompanied\nby severe spectral broadening of the transmitted pulse. For the studied\nirradiation conditions, we find that the threshold fluence increases linearly\nwith the increase of the pulse duration, while the corresponding laser\nintensity threshold decreases. The effect of the high plasma density on the\nstability of diamond lattice is also examined. For near threshold fluences,\nwhen about 5 \\% of valence electrons are promoted into the conduction band, the\nSi-Si bonds are softened and large Fermi degeneracy pressure arises (with\npressure up to 100 kbar). The mechanical instability of the diamond lattice\nsuggests that the large number of electron-hole pairs leads directly to\nultrafast melting of the crystal structure."
    },
    {
        "anchor": "Metamorphic InAs/InGaAs QWs with electron mobilities exceeding\n  $7\\times10^5cm^2/Vs$: We present a study on the influence of strain-relieving InAlAs buffer layers\non metamorphic InAs/InGaAs quantum wells grown by molecular beam epitaxy on\nGaAs. Residual strain in the buffer layer, the InGaAs barrier and the InAs\nwells were assessed by X-ray diffraction and high-resolution transmission\nelectron microscopy. By carefully choosing the composition profile and\nthicknesses of the buffer layer, virtually unstrained InGaAs barriers embedding\nan InAs quantum well with thickness up to 7nm can be grown. This allows\nreaching low-temperature electron mobilities much higher than previously\nreported for samples obtained by metamorphic growth on GaAs, and comparable to\nthe values achieved for samples grown on InP substrates.",
        "positive": "Compositionally Complex Perovskite Oxides as a New Class of Li-Ion Solid\n  Electrolytes: Compositionally complex ceramics (CCCs), including high-entropy ceramics\n(HECs) as a subclass, offer new opportunities of materials discovery beyond the\ntraditional methodology of searching new stoichiometric compounds. Herein, we\nestablish new strategies of tailoring CCCs via a seamless combination of (1)\nnon-equimolar compositional designs and (2) controlling microstructures and\ninterfaces. Using oxide solid electrolytes for all-solid-state batteries as an\nexemplar, we validate these new strategies via discovering a new class of\ncompositionally complex perovskite oxides (CCPOs) to show the possibility of\nimproving ionic conductivities beyond the limit of conventional doping. As an\nexample (amongst the 28 CCPOs examined), we demonstrate that the ionic\nconductivity can be improved by >60% in\n(Li0.375Sr0.4375)(Ta0.375Nb0.375Zr0.125Hf0.125)O3-{\\delta}, in comparison with\nthe state-of-art (Li0.375Sr0.4375)(Ta0.75Zr0.25)O3-{\\delta} (LSTZ) baseline,\nvia maintaining comparable electrochemical stability. Furthermore, the ionic\nconductivity can be improved by another >70% via grain boundary (GB)\nengineering, achieving >270% of the LSTZ baseline. This work suggests\ntransformative new strategies for designing and tailoring HECs and CCCs,\nthereby opening a new window for discovering materials for energy storage and\nmany other applications."
    },
    {
        "anchor": "Carrier diffusion in GaN -- a cathodoluminescence study. III: Nature of\n  nonradiative recombination at threading dislocations: We investigate the impact of threading dislocations with an edge component (a\nor a+c-type) on carrier recombination and diffusion in GaN(0001) layers close\nto the surface as well as in the bulk. To this end, we utilize\ncathodoluminescence imaging of the top surface of a GaN(0001) layer with a\ndeeply buried (In,Ga)N quantum well. Varying the acceleration voltage of the\nprimary electrons and comparing the signal from the layer and the quantum well\nenables us to probe carrier recombination at depths ranging from the close\nvicinity of the surface to the position of the quantum well. Our experiments\nare accompanied by fully three-dimensional Monte Carlo simulations of carrier\ndrift, diffusion, and recombination in the presence of the surface, the quantum\nwell, and the dislocation, taking into account the dislocation strain field and\nthe resulting piezoelectric field at the dislocation outcrop. Near the surface,\nthis field establishes an exciton dead zone around the dislocation, the extent\nof which is not related to the carrier diffusion length. However, reliable\nvalues of the carrier diffusion length can be extracted from the dipole-like\nenergy shift observed in hyperspectral cathodoluminescence maps recorded around\nthe dislocation outcrop at low acceleration voltages. For high acceleration\nvoltages, allowing us to probe a depth where carrier recombination is\nunaffected by surface effects, we observe a much stronger contrast than\nexpected from the piezoelectric field alone. This finding provides unambiguous\nexperimental evidence for the strong nonradiative activity of edge threading\ndislocations in bulk GaN and hence also in buried heterostructures.",
        "positive": "Replenish and relax: explaining logarithmic annealing in disordered\n  materials: Fatigue and aging of materials are, in large part, determined by the\nevolution of the atomic-scale structure in response to strains and\nperturbations. This coupling between microscopic structure and long time scales\nremains one of the main challenges in materials study. Focusing on a model\nsystem, ion-damaged crystalline silicon, we combine nanocalorimetric\nexperiments with an off-lattice kinetic Monte Carlo simulation to identify the\natomistic mechanisms responsible for the structural relaxation over long time\nscales. We relate the logarithmic relaxation, observed in a number of systems,\nwith heat-release measurements. The microscopic mechanism associated with\nlogarithmic relaxation can be described as a two-step replenish and relax\nprocess. As the system relaxes, it reaches deeper energy states with\nlogarithmically growing barriers that need to be unlocked to replenish the\nheat-releasing events leading to lower energy configurations."
    },
    {
        "anchor": "Magnetic properties of wurtzite (Ga,Mn)As: Here we report on detailed studies of the magnetic properties of the wurtzite\n(Ga,Mn)As cylindrical shells. Ga$_{0.94}$Mn$_{0.06}$As shells have been grown\nby molecular beam epitaxy at low temperature as a part of multishell cylinders\novergrown on wurtzite (Ga,In)As nanowires cores, synthesized on GaAs (111)B\nsubstrates. Our studies clearly indicate the presence of a low temperature\nferromagnetic coupling, which despite a reasonably high Mn contents of 6\\% is\nlimited only to below 30~K. A set of dedicated measurements shows that despite\na high structural quality of the material the magnetic order has a granular\nform, which gives rise to the dynamical slow-down characteristic to blocked\nsuperparamagnets. The lack of the long range order has been assigned to a very\nlow hole density, caused primarily by numerous compensation donors, arsenic\nantisites, formed in the material due to a specific geometry of the growth of\nthe shells on the nanowire template. The associated electrostatic disorder has\nformed a patchwork of spontaneously magnetized (macrospin) and nonmagnetic\n(paramagnetic) volumes in the material. Using high field results it has been\nevaluated that the total volume taken by the macrospins constitute about 2/3 of\nthe volume of the (Ga,Mn)As whereas in the remaining 1/3 only paramagnetic Mn\nions reside. By establishing the number of the uncoupled ions the two\ncontributions were separated. The Arrott plot method applied to the\nsuperparamagnetic part yielded the first experimental assessment of the\nmagnitude of the spin-spin coupling temperature within the macrospins in\n(Ga,Mn)As, $T_{\\mathrm{C}}=28$~K. In a broader view our results constitute an\nimportant contribution to the still ongoing dispute on the true and the\ndominant form(s) of the magnetism in this model dilute ferromagnetic\nsemiconductor.",
        "positive": "Paramagnetic Fe_xTa_{1-x} alloys for engineering of perpendicularly\n  magnetized tunnel junctions: Exchange coupling between two magnetic layers through an interlayer is of\nbroad interest for numerous recent applications of nano-magnetic systems. In\nthis Letter we study ferromagnetic exchange coupling through amorphous\nparamagnetic Fe-Ta alloys. We show that the exchange coupling depends\nexponentially on spacer thickness and scales with the Fe-Ta susceptibility,\nwhich can be tuned via the alloy composition and/or temperature. Such materials\nare of high interest for the engineering of perpendicularly magnetized\nCoFeB-MgO based tunnel junctions as it enables ferromagnetic coupling of\nmagnetic layers with differing crystalline lattices, suppresses dead layers and\ncan act as an inter-diffusion barrier during annealing."
    },
    {
        "anchor": "SpectroLab: An Open Source Matlab Based Toolbox for High Throughput\n  Spectroscopy Analysis: We present an open source software package SpectroLab a Matlab-based tool\ndeveloped in 2018 for the analysis of spectroscopic data. In this package,\nthere are tools for derivative analysis, stacked energy contours, stacked plots\nfor theory, 3D volumetric plots, core level analysis, and derivative analysis.\nThe package can currently be used for angle-resolved photoemission spectroscopy\n(ARPES) data, with the ability to also be used for other spectroscopic data in\nthe future. We apply this program to the HfP2, ZrSiS, and Hf2Te2P systems to\ndemonstrate its robustness.",
        "positive": "Evidence for existence of Functional Monoclinic Phase in Sodium Niobate\n  based Solid Solution by Powder Neutron Diffraction: We have carried out systematic temperature-dependent neutron diffraction\nmeasurements in conjunction with dielectric spectroscopy from 6 to 300 K for\nsodium niobate based compounds (1-x) NaNbO3 -xBaTiO3 (NNBTx). The dielectric\nconstant is measured both as a function of temperature and frequency. It shows\nan anomaly at different temperatures in cooling and heating cycles and exhibits\na large thermal hysteresis of 150 K for the composition x=0.03. The dielectric\nconstant is found to be dispersive in nature and suggests a relaxor\nferroelectric behavior. In order to explore structural changes as a function of\ntemperature, we analyzed the powder neutron diffraction data for the\ncomposition x=0.03 and 0.05, respectively. Drastic changes are observed in the\npowder profiles near 30.6{\\deg}, 32.1{\\deg} and 34.6{\\deg} in the diffraction\npattern below 200 K during cooling and above 190 K in heating cycles,\nrespectively.The disappearance of superlattice reflection and splitting in main\nperovskite peaks provide a signature for structural phase transition. We\nobserved stabilization of a monoclinic phase (Cc) at low temperature. This\nmonoclinic phase is believed to provide a flexible polarization rotation and\nconsidered to be directly linked to the high performance piezoelectricity in\nmaterials. The thermal hysteresis for composition x=0.03 is larger than x=0.05.\nThis suggests that addition of BaTiO3 in NaNbO3 suppresses the thermal\nhysteresis. It is also observed that the structural phase transition\ntemperature decreases on increasing dopant concentration."
    },
    {
        "anchor": "Electronic and magnetic properties of Ti4O7 predicted by\n  self-interaction corrected density functional theory: Understanding electronic properties of sub-stoichiometric phases of titanium\noxide such as Magn\\'eli phase Ti4O7 is crucial in designing and modeling\nresistive switching devices. Here we present our study on Magn\\'eli phase Ti4O7\ntogether with rutile TiO2 and Ti2O3 using density functional theory methods\nwith atomic-orbital-based self-interaction correction (ASIC). We predict a new\nantiferromagnetic ground state in the low temperature phase (or LT phase), and\nwe explain energy difference with a competing antiferromagnetic state using a\nHeisenberg model. The predicted energy ordering of these states in the LT phase\nis calculated to be robust in a wide range of modeled isotropic strain. We have\nalso investigated the dependence of the electronic structures of the Ti-O\nphases on stoichiometry. The splitting of titanium t2g orbitals is enhanced\nwith increasing oxygen deficiency as Ti-O is reduced. The electronic properties\nof all these phases can be reasonably well described by applying ASIC with a\nstandard value for transition metal oxides of the empirical parameter {\\alpha}\nof 0.5 representing the magnitude of the applied self-interaction correction.",
        "positive": "Comparative study on aging effect in BiFeO3 thin films substituted at A-\n  and B-site: Typical characteristics of aging effect, double hysteresis loops, were\nobserved in (100)-oriented Bi0.95Ca0.05FeO3 (BCFO) and BiFe0.95Ni0.05O3 (BFNO)\nfilms grown on LaNiO3(100)/Si substrates. The double hysteresis loops for BCFO\nfilm become less \"constrained\" with increasing applied voltage compared to that\nfor BFNO, indicating that the aging effect is more severe in the latter. This\ncan be demonstrated by the lower leakage current and smaller dielectric\nconstant for BFNO. These phenomena are explained based on the crystal structure\nand defect chemistry. The defect states of the Bi, Ca, Fe, Ni and O ions were\nclarified by the XPS data."
    },
    {
        "anchor": "Anomalous, anomalous Hall effect in the layered, Kagome, Dirac semimetal\n  KV$_3$Sb$_5$: The electronic anomalous Hall effect (AHE), where charge carriers acquire a\nvelocity component orthogonal to an applied electric field, is one of the most\nfundamental and widely studied phenomena in physics. There are several\ndifferent AHE mechanisms known, and material examples are highly sought after,\nhowever in the highly conductive (skew scattering) regime the focus has\ncentered around ferromagnetic metals. Here we report the observation of a giant\nextrinsic AHE in KV$_3$Sb$_5$, an exfoliable, Dirac semimetal with a Kagome\nlayer of Vanadium atoms. Although there has been no reports of magnetic\nordering down to 0.25 K, the anomalous Hall conductivity (AHC) reaches\n$\\approx$ 15,507 $\\Omega^{-1}$cm$^{-1}$ with an anomalous Hall ratio (AHR) of\n$\\approx$ 1.8$ \\%$; an order of magnitude larger than Fe. Defying expectations\nfrom skew scattering theory, KV$_3$Sb$_5$ shows an enhanced skew scattering\neffect that scales quadratically, not linearly, with the longitudinal\nconductivity ($\\sigma_{xx}$), opening the possibility of reaching an anomalous\nHall angle (AHA) of 90$^{\\circ}$ in metals; an effect thought reserved for\nquantum anomalous Hall insulators. This observation raises fundamental\nquestions about the AHE and opens a new frontier for AHE (and correspondingly\nSHE) exploration, stimulating investigation in a new direction of materials,\nincluding metallic geometrically frustrated magnets, spin-liquid candidates,\nand cluster magnets.",
        "positive": "Superglitter and squarodiamond, novel C12 (sp2/sp3) and C16 (sp3)\n  allotropes from first principles: Original carbon allotropes C12 and C16 called superglitter and squarodiamond\nfrom relationships with literature glitter and squaroglitter respectively are\nshown through DFT-based geometry to be cohesive with energy dependent\nproperties as hardness from the elastic constants, the phonon band structures,\nand thermal behavior related to diamond. Like C6 glitter, C12 superglitter\nexhibiting mixed sp2-sp3 carbon hybridization shows metallic behavior and\nmoderate hardness and metallic behavior arising from trigonal C(sp2) forming\nC=C pairs connecting tetrahedra. Oppositely, C16 showing square C4 motifs as in\nsquaroglitter characterized by both sp2-sp3 carbons, is characterized by edge\nand corner sharing tetrahedra with only sp3 carbons resulting in insulating\nbehavior and shear modulus and Vickers hardness H(V) larger than 100 GPa as\nwell as heat capacity alike diamond, whence its labeling as squarodiamond. The\nnovel carbon allotropes are proposed as an opportunity to enrich the carbon\ndatabase and the materials science with potentials of applications as abrasives\nand in electronic devices."
    },
    {
        "anchor": "Sound velocity measurements of tantalum under shock compression in the\n  10-110 GPa range: The high-pressure melting curve of tantalum (Ta) has been the center of a\nlong-standing controversy. Sound velocities along the Hugoniot curve are\nexpected to help in understanding this issue. To that end, we employed a\ndirect-reverse impact technique and velocity interferometry to determine sound\nvelocities of Ta under shock compression in the 10-110 GPa pressure range. The\nmeasured longitudinal sound velocities show an obvious kink at ~60 GPa as a\nfunction of shock pressure, while the bulk sound velocities show no\ndiscontinuity. Such observation could result from a structural transformation\nassociated with a negligible volume change or an electronic topological\ntransition.",
        "positive": "Measurement of normal contact stiffness of fractal rough surfaces: We investigate the effects of roughness and fractality on the normal contact\nstiffness of rough surfaces. Samples of isotropically roughened aluminium\nsurfaces are considered. The roughness and fractal dimension were altered\nthrough blasting using different sized particles. Subsequently, surface\nmechanical attrition treatment (SMAT) was applied to the surfaces in order to\nmodify the surface at the microscale. The surface topology was characterised by\ninterferometry based profilometry. The normal contact stiffness was measured\nthrough nanoindentation with a flat tip utilising the partial unloading method.\nWe focus on establishing the relationships between surface stiffness and\nroughness, combined with the effects of fractal dimension. The experimental\nresults, for a wide range of surfaces, showed that the measured contact\nstiffness depended very closely on surfaces' root mean squared (RMS) slope and\ntheir fractal dimension, with correlation coefficients of around 90\\%, whilst a\nrelatively weak correlation coefficient of 57\\% was found between the contact\nstiffness and RMS roughness."
    },
    {
        "anchor": "Fabrication of Hybrid Nanostructures via Nanoscale Laser-Induced\n  Reshaping for Advanced Light Manipulation: Hybrid nanophotonics based on metal-dielectric nanostructures unifies the\nadvantages of plasmonics and all-dielectric nanophotonics providing strong\nlocalization of light, magnetic optical response and specifically designed\nscattering properties. Here we demonstrate a novel approach for fabrication of\nordered hybrid nanostructures via femtosecond laser melting of asymmetrical\nmetal-dielectric (Au-Si) nanoparticles created by lithographical methods. The\napproach allows selective reshaping of the metal components of the hybrid\nnanoparticles without affecting dielectric ones. We apply the developed\napproach for tuning of the hybrid nanostructures scattering properties in the\nvisible range. The experimental results are supported by molecular dynamics\nsimulation and numerical solving of Maxwell equations.",
        "positive": "Structural Complexity and Phonon Physics in 2D Arsenenes: In the quest for stable 2D arsenic phases, four different structures have\nbeen recently claimed to be stable. We show that, due to phonon contributions,\nthe relative stability of those structures differs from previous reports and\ndepends crucially on temperature. We also show that one of those four phases is\nin fact mechanically unstable. Furthermore, our results challenge the common\nassumption of an inverse correlation between structural complexity and thermal\nconductivity. Instead, a richer picture emerges from our results, showing how\nharmonic interactions, anharmonicity and symmetries all play a role in\nmodulating thermal conduction in arsenenes. More generally, our conclusions\nhighlight how vibrational properties are an essential element to be carefully\ntaken into account in theoretical searches for new 2D materials."
    },
    {
        "anchor": "Rapid screening of molecular beam epitaxy conditions for monoclinic\n  (InxGa1-x)2O3 alloys: Molecular beam epitaxy is one of the highest quality growth methods, capable\nof achieving theoretical material property limits and unprecedented device\nperformance. However, such ultimate quality usually comes at the cost of\npainstaking optimization of synthesis conditions and slow experimental\niteration rates. Here we report on high-throughput molecular beam epitaxy with\nrapid screening of synthesis conditions using a novel cyclical growth and\nin-situ etch method. This novel approach leverages sub-oxide desorption present\nduring molecular beam epitaxy and as such should be broadly applicable to other\nmaterial systems. As a proof of concept, this method is applied to rapidly\ninvestigate the growth space for the ternary alloy (InxGa1-x)2O3 on (010)\noriented beta-Ga2O3 substrates using in-situ reflection high energy electron\ndiffraction measurements. Two distinct growth regimes are identified and\nanalyzed using machine learning image recognition algorithms, the first\nstabilizing a streaky 2x surface reconstruction typical of In-catalyzed\nbeta-Ga2O3 growth, and the second exhibiting a spotty/faceted pattern typical\nof phase separation. Targeted growth of (InxGa1-x)2O3 is performed under\nconditions near the boundary of the two regimes resulting in a 980 nm thick\nepitaxial layer with In mole fraction up to 5.6%. The cyclical growth/etch\nmethod retains the ~1 nm surface roughness of the single crystal substrate,\nincreases experimental throughput approximately 6x, and improves single crystal\nsubstrate utilization by >40x. The high-throughput MBE method enables rapid\ndiscovery of growth regimes for ultra-wide bandgap oxide alloys for power\nconversion devices operating with high efficiency at high voltages and\ntemperatures, as well as optical devices such as ultraviolet photodetectors.",
        "positive": "The effect of initial texture on multiple necking formation in\n  polycrystalline thin rings subjected to dynamic expansion: In this paper, we have investigated, using finite element calculations, the\neffect of initial texture on the formation of multiple necking patterns in\nductile metallic rings subjected to rapid radial expansion. The mechanical\nbehavior of the material has been modeled with the elasto-viscoplastic single\ncrystal constitutive model developed by \\citet{marin2006}. The polycrystalline\nmicrostructure of the ring has been generated using random Voronoi seeds. Both\n$5000$ grain and $15000$ grain aggregates have been investigated, and for each\npolycrystalline aggregate three different spatial distributions of grains have\nbeen considered. The calculations have been performed within a wide range of\nstrain rates varying from $1.66 \\cdot 10^4 ~ \\text{s}^{-1}$ to $3.33 \\cdot 10^5\n~ \\text{s}^{-1}$, and the rings have been modeled with four different initial\ntextures: isotropic texture, $\\left\\langle 001\\right\\rangle\\parallel\\Theta$\nGoss texture, $\\left\\langle 001\\right\\rangle\\parallel$ R Goss texture and\n$\\left\\langle 111\\right\\rangle\\parallel$ Z fiber texture. The finite element\nresults show that: (i) the spatial distribution of grains affects the location\nof the necks, (ii) the decrease of the grain size delays the formation of the\nnecking pattern and increases the number of necks, (iii) the initial texture\naffects the number of necks, the location of the necks, and the necking time,\n(iv) the development of the necks is accompanied by a local increase of the\nslip activity. This work provides new insights into the effect of\ncrystallographic microstructure on dynamic plastic localization and guidelines\nto tailor the initial texture in order to delay dynamic necking formation and,\nthus, to improve the energy absorption capacity of ductile metallic materials\nat high strain rates."
    },
    {
        "anchor": "Anisotropic ferromagnetism in carbon doped zinc oxide from\n  first-principles studies: A density functional theory study of substitutional carbon impurities in ZnO\nhas been performed, using both the generalized gradient approximation (GGA) and\na hybrid functional (HSE06) as exchange-correlation functional. It is found\nthat the non-spinpolarized C$_\\mathrm{Zn}$ impurity is under almost all\nconditions thermodynamically more stable than the C$_\\mathrm{O}$ impurity which\nhas a magnetic moment of $2\\mu_{\\mathrm{B}}$, with the exception of very O-poor\nand C-rich conditions. This explains the experimental difficulties in sample\npreparation in order to realize $d^{0}$-ferromagnetism in C-doped ZnO. From GGA\ncalculations with large 96-atom supercells, we conclude that two\nC$_\\mathrm{O}$-C$_\\mathrm{O}$ impurities in ZnO interact ferromagnetically, but\nthe interaction is found to be short-ranged and anisotropic, much stronger\nwithin the hexagonal $ab$-plane of wurtzite ZnO than along the c-axis. This\nlayered ferromagnetism is attributed to the anisotropy of the dispersion of\ncarbon impurity bands near the Fermi level for C$_{\\mathrm{O}}$ impurities in\nZnO. From the calculated results, we derive that a C$_{\\mathrm{O}}$\nconcentration between 2% and 6% should be optimal to achieve\n$d^{0}$-ferromagnetism in C-doped ZnO.",
        "positive": "Excitons and stacking order in h-BN: The strong excitonic emission at 5.75 eV of hexagonal boron nitride (h-BN)\nmakes this material one of the most promising candidate for light emitting\ndevices in the far ultraviolet (UV). However, single excitons occur only in\nperfect monocrystals that are extremely hard to synthesize, while regular h-BN\nsamples present a complex emission spectrum with several additional peaks. The\nmicroscopic origin of these additional emissions has not yet been understood.\nIn this work we address this problem using an experimental and theoretical\napproach that combines nanometric resolved cathodoluminescence, high resolution\ntransmission electron microscopy and state of the art theoretical spectroscopy\nmethods. We demonstrate that emission spectra are strongly inhomogeneus within\nindividual flakes and that additional excitons occur at structural\ndeformations, such as faceted plane folds, that lead to local changes of the\nh-BN stacking order."
    },
    {
        "anchor": "Linking Order to Strength in Metals: The metallurgy and materials communities have long known and exploited\nfundamental links between chemical and structural ordering in metallic solids\nand their mechanical properties. The highest reported strength achievable\nthrough the combination of multiple metals (alloying) has rapidly climbed and\ngiven rise to new classifications of materials with extraordinary properties.\nMetallic glasses and high-entropy alloys are two limiting examples of how\ntailored order can be used to manipulate mechanical behavior. Here, we show\nthat the complex electronic-structure mechanisms governing the peak strength of\nalloys and pure metals can be reduced to a few physically-meaningful parameters\nbased on their atomic arrangements and used (with no fitting parameters) to\npredict the maximum strength of any metallic solid, regardless of degree of\nstructural or chemical ordering. Predictions of maximum strength based on the\nactivation energy for a stress-driven phase transition to an amorphous state is\nshown to accurately describe the breakdown in Hall-Petch behavior at the\nsmallest crystallite sizes for pure metals, intermetallic compounds, metallic\nglasses, and high-entropy alloys. This activation energy is also shown to be\ndirectly proportional to interstitial (electronic) charge density, which is a\ngood predictor of ductility, stiffness (moduli), and phase stability in\nhigh-entropy alloys, and in solid metals generally. The proposed framework\nsuggests the possibility of coupling ordering and intrinsic strength to\nmechanisms like dislocation nucleation, hydrogen embrittlement, and transport\nproperties. It additionally opens the prospect for greatly accelerated\nstructural materials design and development to address materials challenges\nlimiting more sustainable and efficient use of energy.",
        "positive": "Cyclotron Resonance of Itinerant Holes in Ferromagnetic InMnAs/GaSb\n  Heterostructures: We report the first observation of hole cyclotron resonance (CR) in\nferromagnetic InMnAs/GaSb heterostructures both in the high-temperature\nparamagnetic phase and the low-temperature ferromagnetic phase. We clearly\nresolve two resonances that exhibit strong temperature dependence in position,\nlinewidth, and intensity. We attribute the two resonances to the so-called\nfundamental CR transitions expected for delocalized holes in the valence band\nin the magnetic quantum limit, demonstrating the existence of $p$-like\nitinerant holes that are describable within the Luttinger-Kohn effective mass\ntheory."
    },
    {
        "anchor": "Efficiency analysis of betavoltaic elements: The conversion of energy of electrons produced by a radioactive source into\nelectricity in a Si and SiC $\\textit{p-n}$ junctions is modeled. The features\nof the generation function describing the electron-hole pair production by an\nelectron flow and the emergence of a \"dead layer\" are discussed. The collection\nefficiency, $Q$, describing the rate of electron-hole pair production by\nincident beta particles, is calculated taking into account the presence of the\n\"dead layer\". It is shown that in the case of high-grade Si $\\textit{p-n}$\njunctions, the collection efficiency, $Q$, of electron-hole pairs created by a\nhigh-energy electrons flux, e.g. Pm-147 beta flux, is close or equal to 1 in a\nwide range of electron energies. For SiC junctions, $Q$ is large enough (about\n1) only for electrons with relatively low energies of about 5 keV, as produced,\ne.g., by a tritium source, and decreases rapidly with further increase of\nelectron energy. The conditions, under which the influence of the \"dead layer\"\non the collection efficiency is negligible, are determined. The open-circuit\nvoltage is obtained for realistic values of the minority carriers' diffusion\ncoefficient and lifetime in Si and SiC $\\textit{p-n}$ junctions irradiated by a\nhigh-energy electrons flux. Our calculations allow us to estimate the\nattainable efficiency of betavoltaic elements.",
        "positive": "Universal shapes formed by two interacting cracks: We investigate the origins of the widely-observed \"en passant\" crack pattern\nwhich forms through interactions between two approaching cracks. A rectangular\nelastic plate is notched on each long side and then subjected to quasistatic\nuniaxial strain from the short side. The two cracks propagate along\napproximately straight paths until they pass each other, after which they curve\nand release a lenticular fragment. We find that for materials with diverse\nmechanical properties, the shape of this fragment has an aspect ratio of 2:1,\nwith the length scale set by the initial crack offset $s$ and the time scale\nset by the ratio of $s$ to the pulling velocity. The cracks have a universal\nsquare root shape which we understand using a simple geometric model of the\ncrack-crack interaction."
    },
    {
        "anchor": "Phase-field modeling of biomineralization in mollusks and corals:\n  Microstructure vs. formation mechanism: While biological crystallization processes have been studied on the\nmicroscale extensively, models addressing the mesoscale aspects of such\nphenomena are rare. In this work, we investigate whether the phase-field theory\ndeveloped in materials science for describing complex polycrystalline\nstructures on the mesoscale can be meaningfully adapted to model\ncrystallization in biological systems. We demonstrate the abilities of the\nphase-field technique by modeling a range of microstructures observed in\nmollusk shells and coral skeletons, including granular, prismatic,\nsheet/columnar nacre, and sprinkled spherulitic structures. We also compare two\npossible micromechanisms of calcification: the classical route via ion-by-ion\naddition from a fluid state and a non-classical route, crystallization of an\namorphous precursor deposited at the solidification front. We show that with\nappropriate choice of the model parameters microstructures similar to those\nfound in biomineralized systems can be obtained along both routes, though the\ntimescale of the non-classical route appears to be more realistic. The\nresemblance of the simulated and natural biominerals suggests that, underneath\nthe immense biological complexity observed in living organisms, the underlying\ndesign principles for biological structures may be understood with simple math,\nand simulated by phase-field theory.",
        "positive": "A strongly robust Weyl fermion semimetal state in Ta$_{3}$S$_{2}$: Weyl semimetals are extremely interesting. Although the first Weyl semimetal\nwas recently discovered in TaAs, research progress is still significantly\nhindered due to the lack of robust and ideal materials candidates. In order to\nobserve the many predicted exotic phenomena that arise from Weyl fermions, it\nis of critical importance to find robust and ideal Weyl semimetals, which have\nfewer Weyl nodes and more importantly whose Weyl nodes are well separated in\nmomentum space and are located close to the chemical potential in energy. In\nthis paper, we propose by far the most robust and ideal Weyl semimetal\ncandidate in the inversion breaking, single crystalline compound tantalum\nsulfide Ta$_3$S$_2$ with new and novel properties beyond TaAs. We find that\nTa$_3$S$_2$ has only 8 Weyl nodes, all of which have the same energy that is\nmerely 10 meV below the chemical potential. Crucially, our results show that\nTa$_3$S$_2$ has the largest $k$-space separation between Weyl nodes among known\nWeyl semimetal candidates, which is about twice larger than TaAs and twenty\ntimes larger than the predicted value in WTe$_2$. Moreover, we predict that\nincreasing the lattice by $<4\\%$ can annihilate all Weyl nodes, driving a novel\ntopological metal-to-insulator transition from a Weyl semimetal state to a\ntopological insulator state. We further discover that changing the lattice\nconstant can move the Weyl nodes and the van Hove singularities with enhanced\ndensity of states to the chemical potential. Our prediction provides a\ncritically needed robust candidate for this rapidly developing field. The well\nseparated Weyl nodes, the topological metal-to-insulator transition and the\nremarkable tunabilities suggest Ta$_3$S$_2$'s potential as the ideal platform\nin future device-applications based on Weyl semimetals."
    },
    {
        "anchor": "Bulk photonic metamaterial with hyperbolic dispersion: In this work, we demonstrate a self-standing bulk three-dimensional\nmetamaterial based on the network of silver nanowires in an alumina membrane.\nThis constitutes an anisotropic effective medium with hyperbolic dispersion,\nwhich can be used in sub-diffraction imaging or optical cloaks. Highly\nanisotropic dielectric constants of the material range from positive to\nnegative, and the transmitted laser beam shifts both toward the normal to the\nsurface, as in regular dielectrics, and off the normal, as in anisotropic\ndielectrics with the refraction index smaller than one. The designed photonic\nmetamaterial is the thickest reported in the literature, both in terms of its\nphysical size 1cm x 1cm x 51 mm, and the number of vacuum wavelengths, N=61 at\nl=0.84 mm.",
        "positive": "Surface band characters of Weyl semimetal candidate material MoTe$_2$\n  revealed by one-step ARPES theory: The layered 2D-material MoTe$_2$ in the T$_d$ crystal phase is a semimetal\nwhich has theoretically been predicted to possess topologically non-trivial\nbands corresponding to Weyl fermions. Clear experimental evidence by\nangle-resolved photoemission spectroscopy (ARPES) is, however, lacking, which\ncalls for a careful examination of the relation between ground state band\nstructure calculations and ARPES intensity plots. Here we report a study of the\nnear Fermi-energy band structure of MoTe$_2$(T$_d$) by means of ARPES\nmeasurements, density functional theory, and one-step-model ARPES calculations.\nGood agreement between theory and experiment is obtained. We analyze the\norbital character of the surface bands and its relation to the ARPES\npolarization dependence. We find that light polarization has a major efect on\nwhich bands can be observed by ARPES. For s-polarized light, the ARPES\nintensity is dominated by subsurface Mo d orbitals, while p-polarized light\nreveals the bands composed mainly derived from Te p orbitals. Suitable light\npolarization for observing either electron or hole pocket are determined"
    },
    {
        "anchor": "Inhomogeneous Magnetoelectric Effect on Defect in Multiferroic Material:\n  Symmetry Prediction: Inhomogeneous magnetoelectric effect in magnetization distribution\nheterogeneities (0-degree domain walls) appeared on crystal lattice defect of\nthe multiferroic material has been investigated. Magnetic symmetry based\npredictions of kind of electrical polarization distribution in their volumes\nwere used. It was found that magnetization distribution heterogeneity with any\nsymmetry produces electrical polarization. Results were systemized in scope of\nmicromagnetic structure chirality. It was shown that all 0-degree domain walls\nwith time-noninvariant chirality have identical type of spatial distribution of\nthe magnetization and polarization.",
        "positive": "Gradient-induced Dzyaloshinskii-Moriya interaction: The Dzyaloshinskii-Moriya interaction (DMI) that arises in the magnetic\nsystems with broken inversion symmetry plays an essential role in topological\nspintronics. Here, by means of atomistic spin calculations, we study an\nintriguing type of DMI (g-DMI) that emerges in the films with composition\ngradient. We show that both the strength and chirality of g-DMI can be\ncontrolled by the composition gradient even in the disordered system. The\nlayer-resolved analysis of g-DMI unveils its additive nature inside the bulk\nlayers and clarifies the linear thickness dependence of g-DMI observed in\nexperiments. Furthermore, we demonstrate the g-DMI induced chiral magnetic\nstructures, such as spin spirals and skyrmions, and the g-DMI driven field-free\nspin-orbit torque (SOT) switching, both of which are crucial towards practical\ndevice application. These results elucidate the underlying mechanisms of g-DMI\nand open up a new way to engineer the topological magnetic textures."
    },
    {
        "anchor": "Virtual reassembling of 3D fragments for the data-driven analysis of\n  fracture mechanisms in composite materials: This paper introduces a novel method for characterizing fracture mechanisms\nin composite materials using 3D image data gained by computed tomography (CT)\nmeasurements. In mineral liberation, the understanding of these mechanisms is\ncrucial, particularly whether fractures occur along the boundaries of mineral\nphases (intergranular fracture) and/or within mineral phases (transgranular\nfracture). Conventional techniques for analyzing fracture mechanisms are\nfocused on globally comparing the surface exposure of mineral phases extracted\nfrom image measurements before and after fracture. Instead, we present a\nvirtual reassembling algorithm based on image registration techniques, which is\napplied to 3D data of composite materials before and after fracture in order to\ndetermine and characterize the individual fracture surfaces. This enables us to\nconduct a local quantitative analysis of fracture mechanisms by voxelwise\ncomparing adjacent regions at fracture surfaces. A quantitative analysis of\nfracture mechanisms is especially important in the context of geometallurgical\nrecycling processes. As primary deposits are decreasing worldwide, the focus is\nshifting to secondary raw materials containing low concentrations of valuable\nelements such as lithium. To extract these elements, they can be enriched as\nengineered artificial minerals in the slag phase of appropriately designed\ncooling processes. The subsequent liberation through comminution processes,\nsuch as crushing, is essential for the extraction of valuable minerals. A\nbetter understanding of crushing processes, especially fracture mechanisms in\nslags, is crucial for the success of recycling. The reassembling algorithm\npresented in this paper is evaluated through a simulation study, followed by an\napplication to a naturally occurring ore and a slag resulting from a recycling\nprocess.",
        "positive": "Electronic Transport Properties of Pentacene Single Crystals upon\n  Exposure to Air: We report the effect of air exposure on the electronic properties of\npentacene single crystals. Air can diffuse reversibly in and out of the\ncrystals and controls the physical properties. We discern two competing\nmechanisms that modulate the electronic transport. The presence of oxygen\nincreases the hole conduction, as in dark four O2 molecules introduce one\ncharge carrier. This effect is enhanced by the presence of visible light.\nContrarily, water, present in ambient air, is incorporated in the crystal\nlattice and forms trapping sites for injected charges."
    },
    {
        "anchor": "Logarithmic growth law in the two-dimensional Ising spin glass state\n  resulting from the electron doping in single-layered manganites: The ac-susceptibility of the electron doped single-layered manganite\nLa$_{1.1}$Sr$_{0.9}$MnO$_4$ is analyzed in detail. A quasi two-dimensional\n(2$D$) antiferromagnetic (AFM) order with Ising anisotropy is stabilized below\n$T_N$ $\\sim$ 80K. We show that below $T_N$, a rare 2$D$ spin-glass (SG)\ncorrelation develops with the same Ising anisotropy as the AFM state. Using\nsimple scaling arguments of the droplet model, we derive a scaling form for the\nac-susceptibility data of a 2$D$ SG, which our experimental data follows fairly\nwell. Due to simplifications in this 2$D$ case, the proposed scaling form only\ncontains two unknown variables $\\psi\\nu$ and $\\tau_0$. Hence, the logarithmic\ngrowth law of the SG correlation predicted by the droplet model is convincingly\nevidenced by the scaling of our experimental data. The origin and nature of\nthis 2$D$ SG state is also discussed.",
        "positive": "Benchmarking the Performance of Bayesian Optimization across Multiple\n  Experimental Materials Science Domains: In the field of machine learning (ML) for materials optimization, active\nlearning algorithms, such as Bayesian Optimization (BO), have been leveraged\nfor guiding autonomous and high-throughput experimentation systems. However,\nvery few studies have evaluated the efficiency of BO as a general optimization\nalgorithm across a broad range of experimental materials science domains. In\nthis work, we evaluate the performance of BO algorithms with a collection of\nsurrogate model and acquisition function pairs across five diverse experimental\nmaterials systems, namely carbon nanotube polymer blends, silver nanoparticles,\nlead-halide perovskites, as well as additively manufactured polymer structures\nand shapes. By defining acceleration and enhancement metrics for general\nmaterials optimization objectives, we find that for surrogate model selection,\nGaussian Process (GP) with anisotropic kernels (automatic relevance detection,\nARD) and Random Forests (RF) have comparable performance and both outperform\nthe commonly used GP without ARD. We discuss the implicit distributional\nassumptions of RF and GP, and the benefits of using GP with anisotropic kernels\nin detail. We provide practical insights for experimentalists on surrogate\nmodel selection of BO during materials optimization campaigns."
    },
    {
        "anchor": "Experimental evidence for topological surface states wrapping around\n  bulk SnTe crystal: We demonstrate that the metallic topological surface states wrap on all sides\nthe 3D topological crystalline insulator SnTe. This is achieved by studying\noscillatory quantum magneto-transport and magnetization at tilted magnetic\nfields which enables us to observe simultaneous contributions from neighbouring\nsample sides. Taking into account pinning of the Fermi energy by the SnTe\nreservoir we successfully describe theoretically the de Haas-van Alphen\noscillations of magnetization. The determined \\pi-Berry phase of surface states\nconfirms their Dirac fermion character. We independently observe oscillatory\ncontributions of magneto-transport and magnetization originating from the bulk\nSnTe reservoir of high hole density. It is concluded that the bulk and surface\nLandau states exist in parallel. Our main result that the bulk reservoir is\nsurrounded on all sides by the topological surface states has an universal\ncharacter.",
        "positive": "Factors limiting ferroelectric field-effect doping in complex-oxide\n  heterostructures: Ferroelectric field-effect doping has emerged as a powerful approach to\nmanipulate the ground state of correlated oxides, opening the door to a new\nclass of field-effect devices. However, this potential is not fully exploited\nso far, since the size of the field-effect doping is generally much smaller\nthan expected. Here we study the limiting factors through magneto-transport,\nscanning transmission electron and piezo-response force microscopy in\nferroelectric/superconductor (YBa2Cu3O7-{\\delta} /BiFeO3) heterostructures, a\nmodel system showing very strong field-effects. Still, we find that they are\nlimited in the first place by an incomplete ferroelectric switching. This can\nbe explained by the existence of a preferential polarization direction set by\nthe atomic terminations at the interface. More importantly, we also find that\nthe field-effect carrier doping is accompanied by a strong modulation of the\ncarrier mobility. Besides making quantification of field-effects via Hall\nmeasurements not straightforward, this finding suggests that ferroelectric\npoling produces structural changes (e.g. charged defects or structural\ndistortions) in the correlated oxide channel. Those findings have important\nconsequences for the understanding of ferroelectric field-effects and for the\nstrategies to further enhance them."
    },
    {
        "anchor": "Basics of the magnetocaloric effect: This chapter reviews the basic physics and thermodynamics that govern\nmagnetocaloric materials. The thermodynamics of magnetic materials is discussed\nby introducing relevant free energy terms together with their microscopic\norigin leading to a discussion of the sources of entropy that can change in an\napplied magnetic field. Such entropies account for measurable magnetocaloric\neffects, especially in the vicinity of magnetic phase transitions. Particular\nattention is devoted to first order magnetic transitions that involve the\ncoupling of spin, lattice, electronic and anisotropic magneto-crystalline\ndegrees of freedom. The problem of irreversibility and hysteresis, present in\nmagnetocaloric materials with first order phase transitions is discussed in the\ncontext of out-of-equilibrium thermodynamics and hysteresis modeling.",
        "positive": "Artificial Intelligence-Enabled Optimization of Battery-Grade Lithium\n  Carbonate Production: By 2035, the need for battery-grade lithium is expected to quadruple. About\nhalf of this lithium is currently sourced from brines and must be converted\nfrom a chloride into lithium carbonate (Li2CO3) through a process called\nsoftening. Conventional softening methods using sodium or potassium salts\ncontribute to carbon emissions during reagent mining and battery manufacturing,\nexacerbating global warming. This study introduces an alternative approach\nusing carbon dioxide (CO2(g)) as the carbonating reagent in the lithium\nsoftening process, offering a carbon capture solution. We employed an active\nlearning-driven high-throughput method to rapidly capture CO2(g) and convert it\nto lithium carbonate. The model was simplified by focusing on the elemental\nconcentrations of C, Li, and N for practical measurement and tracking, avoiding\nthe complexities of ion speciation equilibria. This approach led to an\noptimized lithium carbonate process that capitalizes on CO2(g) capture and\nimproves the battery metal supply chain's carbon efficiency."
    },
    {
        "anchor": "Atomic-layer controlled THz Spintronic emission from Epitaxially grown\n  Two dimensional PtSe$_2$/ferromagnet heterostructures: Terahertz (THz) Spintronic emitters based on ferromagnetic/metal junctions\nhave become an important technology for the THz range, offering powerful and\nultra-large spectral bandwidths. These developments have driven recent\ninvestigations of two-dimensional (2D) materials for new THz spintronic\nconcepts. 2D materials, such as transition metal dichalcogenides (TMDs), are\nideal platforms for SCC as they possess strong spin-orbit coupling (SOC) and\nreduced crystal symmetries. Moreover, SCC and the resulting THz emission can be\ntuned with the number of layers, electric field or strain. Here, epitaxially\ngrown 1T-PtSe$_2$ and sputtered Ferromagnet (FM) heterostructures are presented\nas a novel THz emitter where the 1T crystal symmetry and strong SOC favor SCC.\nHigh quality of as-grown PtSe$_2$ layers is demonstrated and further FM\ndeposition leaves the PtSe$_2$ unaffected, as evidenced with extensive\ncharacterization. Through this atomic growth control, the unique thickness\ndependent electronic structure of PtSe$_2$ allows the control of the THz\nemission by SCC. Indeed, we demonstrate the transition from the inverse\nRashba-Edelstein effect in one monolayer to the inverse spin Hall effect in\nmultilayers. This band structure flexibility makes PtSe$_2$ an ideal candidate\nas a THz spintronic 2D material and to explore the underlying mechanisms and\nengineering of the SCC for THz emission.",
        "positive": "Static Versus Dynamic Friction: The Role of Coherence: A simple model for solid friction is analyzed. It is based on tangential\nsprings representing interlocked asperities of the surfaces in contact. Each\nspring is given a maximal strain according to a probability distribution. At\ntheir maximal strain the springs break irreversibly. Initially all springs are\nassumed to have zero strain, because at static contact local elastic stresses\nare expected to relax. Relative tangential motion of the two solids leads to a\nloss of coherence of the initial state: The springs get out of phase due to\ndifferences in their sizes. This mechanism alone is shown to lead to a\ndifference between static and dynamic friction forces already. We find that in\nthis case the ratio of the static and dynamic coefficients decreases with\nincreasing relative width of the probability distribution, and has a lower\nbound of 1 and an upper bound of 2."
    },
    {
        "anchor": "Point defect dynamics in bcc metals: We present an analysis of the time evolution of self-interstitial atom and\nvacancy (point defect) populations in pure bcc metals under constant\nirradiation flux conditions. Mean-field rate equations are developed in\nparallel to a kinetic Monte Carlo (kMC) model. When only considering the\nelementary processes of defect production, defect migration, recombination and\nabsorption at sinks, the kMC model and rate equations are shown to be\nequivalent and the time evolution of the point defect populations is analyzed\nusing simple scaling arguments. We show that the typically large mismatch of\nthe rates of interstitial and vacancy migration in bcc metals can lead to a\nvacancy population that grows as the square root of time. The vacancy cluster\nsize distribution under both irreversible and reversible attachment can be\ndescribed by a simple exponential function. We also consider the effect of\nhighly mobile interstitial clusters and apply the model with parameters\nappropriate for vanadium and $\\alpha-$iron.",
        "positive": "Terahertz signatures of ultrafast Dirac fermion relaxation at the\n  surface of topological insulators at room temperature: Topologically-protected surface states present rich physics and promising\nspintronic, optoelectronic and photonic applications that require a proper\nunderstanding of their ultrafast carrier dynamics. Here, we investigate these\ndynamics in topological insulators (TIs) of the bismuth and antimony\nchalcogenide family, where we isolate the response of Dirac fermions at the\nsurface from the response of bulk carriers by combining photoexcitation with\nbelow-bandgap terahertz (THz) photons with TI samples with varying Fermi level,\nincluding one sample with the Fermi level located within the bandgap. We\nidentify distinctly faster relaxation of charge carriers in the\ntopologically-protected Dirac surface states (few hundred femtoseconds),\ncompared to bulk carriers (few picoseconds). In agreement with such fast\ncooling dynamics, we observe THz harmonic generation without any saturation\neffects for increasing incident fields, unlike graphene which exhibits strong\nsaturation. This opens up promising avenues for increased THz nonlinear\nconversion efficiencies, and high-bandwidth optoelectronic and spintronic\ninformation and communication applications."
    },
    {
        "anchor": "High-throughput synthesis of thermoelectric Ca$_3$Co$_4$O$_9$ films: Properties of complex oxide thin films can be tuned over a range of values as\na function of mismatch, composition, orientation, and structure. Here, we\nreport a strategy for growing structured epitaxial thermoelectric thin films\nleading to improved Seebeck coefficient. Instead of using single-crystal\nsapphire substrates to support epitaxial growth, Ca$_3$Co$_4$O$_9$ films are\ndeposited, using the Pulsed Laser Deposition technique, onto Al$_2$O$_3$\npolycrystalline substrates textured by Spark Plasma Sintering. The structural\nquality of the 2000 \\AA thin film was investigated by Transmission Electron\nMicroscopy, while the crystallographic orientation of the grains and the\nepitaxial relationships were determined by Electron Back Scatter Diffraction.\nThe use of a polycrystalline ceramic template leads to structured films that\nare in good local epitaxial registry. The Seebeck coefficient is about 170\n$\\mu$V/K at 300 K, a typical value of misfit material with low carrier density.\nThis high-throughput process, called combinatorial substrate epitaxy, appears\nto facilitate the rational tuning of functional oxide films, opening a route to\nthe epitaxial synthesis of high quality complex oxides.",
        "positive": "The multiferroic phase of DyFeO$_{3}$:an ab--initio study: By performing accurate ab-initio density functional theory calculations, we\nstudy the role of $4f$ electrons in stabilizing the magnetic-field-induced\nferroelectric state of DyFeO$_{3}$. We confirm that the ferroelectric\npolarization is driven by an exchange-strictive mechanism, working between\nadjacent spin-polarized Fe and Dy layers, as suggested by Y. Tokunaga [Phys.\nRev. Lett, \\textbf{101}, 097205 (2008)]. A careful electronic structure\nanalysis suggests that coupling between Dy and Fe spin sublattices is mediated\nby Dy-$d$ and O-$2p$ hybridization. Our results are robust with respect to the\ndifferent computational schemes used for $d$ and $f$ localized states, such as\nthe DFT+$U$ method, the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional and the\nGW approach. Our findings indicate that the interaction between the $f$ and $d$\nsublattice might be used to tailor ferroelectric and magnetic properties of\nmultiferroic compounds."
    },
    {
        "anchor": "Simulation of structural and electronic properties of amorphous tungsten\n  oxycarbides: Electron beam induced deposition with tungsten hexacarbonyl W(CO)6 as\nprecursors leads to granular deposits with varying compositions of tungsten,\ncarbon and oxygen. Depending on the deposition conditions, the deposits are\ninsulating or metallic. We employ an evolutionary algorithm to predict the\ncrystal structures starting from a series of chemical compositions that were\ndetermined experimentally. We show that this method leads to better structures\nthan structural relaxation based on guessed initial structures. We approximate\nthe expected amorphous structures by reasonably large unit cells that can\naccommodate local structural environments that resemble the true amorphous\nstructure. Our predicted structures show an insulator to metal transition close\nto the experimental composition at which this transition is actually observed.\nOur predicted structures also allow comparison to experimental electron\ndiffraction patterns.",
        "positive": "Effect of manganese doping on the size effect of lead zirconate titanate\n  thin films and the extrinsic nature of dead layers: We have investigated the size effect in lead zirconate titanate (PZT) thin\nfilms with a range of manganese (Mn) doping concentrations. We found that the\nsize effect in the conventional Pt/PZT/Pt thin-film capacitors could be\nsystematically reduced and almost completely eliminated by increasing Mn doping\nconcentration. The interfacial layer at the electrode-film interface appears to\ndisappear almost entirely for the PZT films with 2% Mn doping levels, confirmed\nby the fits using the conventional in-series capacitor model. Our work\nindicates that the size effect in ferroelectrics is extrinsic in nature,\nsupporting the work by Saad et al. Other implications of our results have also\nbeen discussed. By comparing a variety of experimental studies in the\nliterature we propose a scenario that the dead layer between PZT (or barium\nstrontium titanate, BST) and metal electrodes such as Pt and Au might have a\ndefective pyrochlore/fluorite structure (possibly with a small portion of\nferroelectric perovskite phase)."
    },
    {
        "anchor": "Modeling the microstructural evolution during constrained sintering: A numerical model able to simulate solid-state constrained sintering is\npresented. The model couples an existing kinetic Monte Carlo (kMC) model for\nfree sintering with a finite element model (FEM) for calculating stresses on a\nmicrostructural level. The microstructural response to the local stress as well\nas the FEM calculation of the stress field from the microstructural evolution\nis discussed. The sintering behavior of a sample constrained by a rigid\nsubstrate is simulated. The constrained sintering results in a larger number of\npores near the substrate, as well as anisotropic sintering shrinkage, with\nsignificantly enhanced strain in the central upper part of the sample surface,\nand minimal strain at the edges near the substrate. All these features have\nalso previously been observed experimentally.",
        "positive": "Efficient spin injection through a crystalline AlOx tunnel barrier\n  prepared by the oxidation of an ultra-thin Al epitaxial layer on GaAs: We report that an ultra-thin, post-oxidized aluminum epilayer grown on the\nAlGaAs surface works as a high-quality tunnel barrier for spin injection from a\nferromagnetic metal to a semiconductor. One of the key points of the present\noxidation method is the formation of the crystalline AlOx template layer\nwithout oxidizing the AlGaAs region near the Al/AlGaAs interface. The oxidized\nAl layer is not amorphous but show well-defined single crystalline feature\nreminiscent of the spinel gamma-AlOx phase. A spin-LED consisting of an Fe\nlayer, a crystalline AlOx barrier layer, and an AlGaAs-InGaAs double\nhetero-structure has exhibited circularly polarized electroluminescence with\ncircular polarization of P_{EL} = 0.145 at the remnant magnetization state of\nthe Fe layer, indicating the relatively high spin injection efficiency (epsilon\n= 2P_{EL} / P_{Fe}) of 0.63."
    },
    {
        "anchor": "Ferroelectric nanodomains in epitaxial PbTiO3 films grown on SmScO3 and\n  TbScO3 substrates: Domain structures of 320 nm thin epitaxial films of ferroelectric PbTiO3\ngrown by MOCVD technique in identical conditions on SmScO3 and TbScO3\nperovskite sub- strates have been investigated by Raman spectroscopy and\npiezoresponse force microscopy techniques. Phonon frequency shifts and typical\ndomain structure motifs are discussed. The results reveal strikingly different\ndomain structure architecture: domain structures of the PbTiO3 film grown on\nSmScO3 have dominantly a-domain orientation while strongly preferential\nc-domain orientation was found in the PbTiO3 film grown on the TbScO3\nsubstrate. Differences between the two cases are traced back to the\nfilm-substrate lattice mismatch at the deposition temperature.",
        "positive": "Magnetically active vacancy related defects in irradiated GaN layers: We present the studies of magnetic properties of 2 MeV 4He+-irradiated GaN\ngrown by metal-organic chemical-vapor deposition. Particle irradiation allowed\ncontrollable introduction of Ga-vacancy in the samples. The magnetic moments\nwith concentrations changing between 4.3...8.3x10^17 cm^-3 showing\nsuperparamagnetic blocking at room temperature are observed. The appearance of\nclear hysteresis curve at T = 5 K with coercive field of about H_C = 270 Oe\nsuggests that the formation of more complex Ga vacancy related defects is\npromoted with increasing Ga vacancy content. The small concentration of the\nobserved magnetically-active defects with respect to the total Ga- vacancy\nconcentration suggests that the presence of the oxygen/hydrogen-related vacancy\ncomplexes is the source of the observed magnetic moments."
    },
    {
        "anchor": "On the question of ferromagnetism in alkali metal thin films: Electronic and magnetic structure of $(100)$ films of K and Cs are calculated\nwithin the plane-wave projector augmented wave (PAW) formalism of the density\nfunctional theory (DFT) using both local spin density approximation (LSDA) and\nthe PW91 generalized gradient approximation (GGA). Only a 6 layer Cs film is\nfound to have a ferromagnetic (FM) state which is degenerate with a\nparamagnetic (PM) state within the accuracy of these calculations. This is at\nvariance with the results obtained from a finite thickness uniform jellium\nmodel (UJM). Implications of these results for the experiments on transition\nmetal doped alkali metal thin films and bulk hosts are discussed.",
        "positive": "Scattering anisotropy in HgTe (013) quantum well: We report on a detailed experimental study of the electron transport\nanisotropy in HgTe (013) quantum well of 22 nm width in the directions $[100]$\nand $[03\\bar{1}]$ as the function of the electron density $n$. The anisotropy\nis absent at minimal electron density near the charge neutrality point. The\nanisotropy increases with the increase of n and reaches about 10% when the\nFermi level is within the first subband H1. There is a sharp increase of the\nanisotropy (up to 60%) when the Fermi level reaches the second subband E2. We\nconclude that the first effect is due to the small intra-subband anisotropic\ninterface roughness scattering, and the second one is due to the strongly\nanisotropic inter-subband roughness scattering, but the microscopical reason of\nsuch a strong change in the anisotropy remains unknown."
    },
    {
        "anchor": "Conduction mechanism and magnetotransport in multi-walled carbon\n  nanotubes: We report on a numerical study of quantum diffusion over micron lengths in\ndefect-free multi-walled nanotubes. The intershell coupling allows the electron\nspreading over several shells, and when their periodicities along the nanotube\naxis are incommensurate, which is likely in real materials, the electronic\npropagation is shown to be non ballistic. This results in magnetotransport\nproperties which are exceptional for a disorder free system, and provides a new\nscenario to understand the experiments (A. Bachtold et al. Nature 397, 673\n(1999)).",
        "positive": "3D HR-EBSD characterization of the plastic zone around crack tips in\n  tungsten single crystals at the micron scale: High angular resolution electron backscatter diffraction (HR-EBSD) was\ncoupled with focused ion beam (FIB) slicing to characterize the shape of the\nplastic zone in terms of geometrically necessary dislocations (GNDs) in W\nsingle crystal in 3 dimensions. Cantilevers of similar size with a notch were\nfabricated by FIB and were deformed inside a scanning electron microscope at\ndifferent temperatures (21$^{\\circ}$C, 100$^{\\circ}$C and 200$^{\\circ}$C) just\nabove the micro-scale brittle-to-ductile transition (BDT). J-integral testing\nwas performed to analyse crack growth and determine the fracture toughness. At\nall three temperatures the plastic zone was found to be larger close to the\nfree surface than inside the specimen, similar to macro-scale tension tests.\nHowever, at higher temperature, the 3D shape of the plastic zone changes from\nbeing localized in front of the crack tip to a butterfly-like distribution,\nshielding more efficiently the crack tip and inhibiting crack propagation. A\ncomparison was made between two identically deformed samples, which were\nFIB-sliced from two different directions, to evaluate the reliability of the\nGND density estimation by HR-EBSD. The analysis of the distribution of the Nye\ntensor components was used to differentiate between the types of GNDs nucleated\nin the sample. The role of different types of dislocations in the plastic zone\nis discussed and we confirm earlier findings that the micro-scale BDT of W is\nmainly controlled by the nucleation of screw dislocations in front of the crack\ntip."
    },
    {
        "anchor": "Electronic structure and optical properties of metallic nanoshells: The electronic structure and optical properties of metallic nanoshells are\ninvestigated using a jellium model and the Time Dependent Local Density\nApproximation (TDLDA). An efficient numerical implementation enables\napplications to nanoshells of realistic size with up to a million electrons. We\ndemonstrate how a frequency dependent background polarizability of the jellium\nshell can be included in the TDLDA formalism. The energies of the plasmon\nresonances are calculated for nanoshells of different sizes and with different\ndielectric cores, dielectric embedding media, and dielectric shell backgrounds.\nThe plasmon energies are found to be in good agreement with the results from\nclassical Mie scattering theory using a Drude dielectric function. A comparison\nwith experimental data shows excellent agreement between theory and the\nmeasured frequency dependent absorption spectra.",
        "positive": "Numerical Analysis of Magnetic Domain Energy System in Nano-scale Fe: Magnetic materials generally construct magnetic domains in external field H.\nThese domain structures are changed with the field changes {\\Delta}H\naccompanying the Barkhausen effects. These phenomena are shown using Fe domain\nenergy systems composed of classical magnetic dipole moment interactions. The\nmagnetization curves are created with terraces and jumps, where the flux\nstructure changes produce the Barkhausen noise. The terraces indicate the\ndelays of the magnetization processes for the field H. These numerical\nsimulations are performed in Fe nano-scale regular lattice systems of rods and\nbelts, which directly show the evidences of these basic phenomena."
    },
    {
        "anchor": "More-Realistic Band Gaps from Meta-Generalized Gradient Approximations:\n  Only in a Generalized Kohn-Sham Scheme: Unlike the local density approximation (LDA) and the generalized gradient\napproximation (GGA), calculations with meta-generalized gradient approximations\n(meta-GGA) are usually done according to the generalized Kohn-Sham (gKS)\nformalism. The exchange-correlation potential of the gKS equation is\nnon-multiplicative, which prevents systematic comparison of meta-GGA\nbandstructures to those of the LDA and the GGA. We implement the optimized\neffective potential (OEP) of the meta-GGA for periodic systems, which allows us\nto carry out meta-GGA calculations in the same KS manner as for the LDA and the\nGGA. We apply the OEP to several meta-GGAs, including the new SCAN functional\n[Phys. Rev. Lett. 115, 036402 (2015)]. We find that the KS gaps and KS band\nstructures of meta-GGAs are close to those of GGAs. They are smaller than the\nmore realistic gKS gaps of meta-GGAs, but probably close to the less-realistic\ngaps in the band structure of the exact KS potential, as can be seen by\ncomparing with the gaps of the EXX+RPA OEP potential. The well-known grid\nsensitivity of meta-GGAs is much more severe in OEP calculations.",
        "positive": "Emergence of local geometric laws of step flow in homoepitaxial growth: Below the roughening transition, crystal surfaces exhibit nanoscale line\ndefects, steps, that move by exchanging atoms with their environment. In\nhomoepitaxy, we analytically show how the motion of a step train in vacuum\nunder strong desorption can be approximately described by nonlinear laws that\ndepend on local geometric features such as the curvature of each step, as well\nas suitably defined effective terrace widths. We assume that each step edge, a\nfree boundary, can be represented by a smooth curve in a fixed reference plane\nfor sufficiently long times. Besides surface diffusion and evaporation, the\nprocesses under consideration include kinetic step-step interactions in slowly\nvarying geometries, material deposition on the surface from above, attachment\nand detachment of atoms at steps, step edge diffusion, and step permeability.\nOur methodology relies on boundary integral equations for the adatom fluxes\nresponsible for step flow. By applying asymptotics, which effectively treat the\ndiffusive term of the free boundary problem as a singular perturbation, we\ndescribe an intimate connection of universal character between step kinetics\nand local geometry."
    },
    {
        "anchor": "Temperature dependence of mobility of conducting polymer polyaniline\n  with secondary dopant: The conductivity $\\sigma$ and carrier density $n$ of the conducting polymer\npolyaniline were investigated by changing the concentration $x$ of a secondary\ndopant, meta-cresol. We found that $\\sigma$ changes by four orders of magnitude\nwithin the $x$-range of 1-10 %, while $n$, as estimated from the Hall\nmeasurements, shows a weak dependence on $x$ in the region of 2% <$x$< 50%.\nThese results suggest that $\\sigma$ can be enhanced by the change in the\nmobility $\\mu$. We analyzed the temperature dependence of $\\mu$ by not only the\ncombination of two different types of scattering mechanism, but also by the\npolaron hopping model. The experimental data of $\\mu(T)$ can be explained well\nby the latter model with reasonable fitting parameter values of a small-polaron\nbinding energy and a longitudinal optical phonon frequency.",
        "positive": "Thermodynamics of anharmonic lattices from first-principles: Self-consistent phonon (SCP) theory and its application in computing\nthermodynamic properties of materials are reviewed from a historical\nperspective. Various more recent implementations based on first-principles\nelectronic structure methods using the density functional theory (DFT) have\nbeen discussed. The SCP equations can be derived either from a diagrammatic\nperturbation theory or a variational approach based on free-energy\nminimization. These methods can also be used to predict phase change due to\nphonon softening, and can be extended to study the coupling of phonons to other\ndegrees of freedom in the system."
    },
    {
        "anchor": "Electronic and Phonon Instabilities in Bilayer Graphene under Applied\n  External Bias: We have performed electronic-structure and lattice-dynamics calculations on\nthe AB and AA structures of bilayer graphene. We study the effect of external\nelectric fields and compare results obtained with different levels of theory to\nexisting theoretical and experimental results. Application of an external field\nto the AB bilayer alters the electronic spectrum, with the bands changing under\nbias from a parabolic to a \"Mexican hat\" double-well structure. This results in\na semi-metal-to-semiconductor phase transition, with the size of the induced\nelectronic band-gap being tuneable through the field strength. A reduction of\ncontinuous symmetry from a hexagonal to a triangular lattice is also evidenced\nthrough in-plane electronic charge inhomogeneities between the sublattices.\nWhen spin-orbit coupling is turned on for the AB system, we find that the bulk\ngap decreases, gradually increasing for larger intensities of the bias. Under\nlarge bias the energy dispersion recovers the Mexican hat structure, since the\nenergy interaction between the layers balances the coupling interaction. We\nfind that external bias perturbs the harmonic phonon spectra and leads to\nanomalous behaviour of the out-of-plane flexural ZA and layer-breathing ZO'\nmodes. For the AA system, the electronic and phonon dispersions both remain\nstable under bias, but the phonon spectrum exhibits zone-center imaginary modes\ndue to layer-sliding dynamical instabilities.",
        "positive": "Single-Phase L1$_{0}$-Ordered High Entropy Thin Films with High Magnetic\n  Anisotropy: The vast high entropy alloy (HEA) composition space is promising for\ndiscovery of new material phases with unique properties. We explore the\npotential to achieve rare-earth-free high magnetic anisotropy materials in\nsingle-phase HEA thin films. Thin films of FeCoNiMnCu sputtered on thermally\noxidized Si/SiO$_{2}$ substrates at room temperature are magnetically soft,\nwith a coercivity on the order of 10 Oe. After post-deposition rapid thermal\nannealing (RTA), the films exhibit a single face-centered-cubic (fcc) phase,\nwith an almost 40-fold increase in coercivity. Inclusion of 50 at.% Pt in the\nfilm leads to ordering of a single L1$_{0}$ high entropy intermetallic phase\nafter RTA, along with high magnetic anisotropy and a 3 orders of magnitude\ncoercivity increase. These results demonstrate a promising HEA approach to\nachieve high magnetic anisotropy materials using RTA."
    },
    {
        "anchor": "Superdiffusive heat conduction in semiconductor alloys -- I. Theoretical\n  foundations: Semiconductor alloys exhibit a strong dependence of effective thermal\nconductivity on measurement frequency. So far this quasi-ballistic behaviour\nhas only been interpreted phenomenologically, providing limited insight into\nthe underlying thermal transport dynamics. Here, we show that quasi-ballistic\nheat conduction in semiconductor alloys is governed by L\\'evy superdiffusion.\nBy solving the Boltzmann transport equation (BTE) with ab initio phonon\ndispersions and scattering rates, we reveal a transport regime with fractal\nspace dimension $1 < \\alpha < 2$ and superlinear time evolution of mean square\nenergy displacement $\\sigma^2(t) \\sim t^{\\beta} (1 < \\beta < 2)$. The\ncharacteristic exponents are directly interconnected with the order $n$ of the\ndominant phonon scattering mechanism $\\tau \\sim \\omega^{-n} (n>3)$ and\ncumulative conductivity spectra $\\kappa_{\\Sigma}(\\tau;\\Lambda)\\sim\n(\\tau;\\Lambda)^{\\gamma}$ resolved for relaxation times or mean free paths\nthrough simple relations $\\alpha = 3-\\beta = 1 + 3/n = 2 - \\gamma$. The\nquasi-ballistic transport inside alloys is no longer governed by Brownian\nmotion, but instead dominated by L\\'evy dynamics. This has important\nimplications for the interpretation of thermoreflectance (TR) measurements with\nmodified Fourier theory. Experimental $\\alpha$ values for InGaAs and SiGe,\ndetermined through TR analysis with a novel L\\'evy heat formalism, match ab\ninitio BTE predictions within a few percent. Our findings lead to a deeper and\nmore accurate quantitative understanding of the physics of nanoscale heat flow\nexperiments.",
        "positive": "The dielectric impact of layer distances on exciton and trion binding\n  energies in van der Waals heterostructures: The electronic and optical properties of monolayer transition-metal\ndichalcogenides (TMDs) and van der Waals heterostructures are strongly subject\nto their dielectric environment. In each layer the field lines of the Coulomb\ninteraction are screened by the adjacent material, which reduces the\nsingle-particle band gap as well as exciton and trion binding energies. By\ncombining an electrostatic model for a dielectric hetero-multi-layered\nenvironment with semiconductor many-particle methods, we demonstrate that the\nelectronic and optical properties are sensitive to the interlayer distances on\nthe atomic scale. Spectroscopical measurements in combination with a direct\nsolution of a three-particle Schr\\\"odinger equation reveal trion binding\nenergies that correctly predict recently measured interlayer distances."
    },
    {
        "anchor": "Effect of van der Waals interactions on the stability of SiC polytypes: Density functional theory calculations with a correction of the long-range\ndispersion force, namely the van der Waals (vdW) force, are performed for SiC\npolytypes. The lattice parameters are in good agreement with those obtained\nfrom experiments. Furthermore, the stability of the polytypes in the\nexperiments, which show 3C-SiC as the most stable, are reproduced by the\npresent calculations. The effect of the vdW force on the electronic structure\nand the stability of polytypes are discussed. We observe that the vdW\ninteraction is more sensitive to the cubic site than the hexagonal site. Thus,\nthe influence of the vdW force increases with decreasing the hexagonality of\nthe polytype, which results in the confirmation that the most stable polytype\nis 3C-SiC.",
        "positive": "An invisible non-volatile solid-state memory: Information technologies require entangling data stability with encryption\nfor a next generation of secure data storage. Current magnetic memories,\nranging from low-density stripes up to high-density hard drives, can ultimately\nbe detected using routinely available probes or manipulated by external\nmagnetic perturbations. Antiferromagnetic resistors feature unrivalled\nrobustness but the stable resistive states reported scarcely differ by more\nthan a fraction of a percent at room temperature. Here we show that the\nmetamagnetic (ferromagnetic to antiferromagnetic) transition in intermetallic\nFe0.50Rh0.50 can be electrically controlled in a magnetoelectric\nheterostructure to reveal or cloak a given ferromagnetic state. From an aligned\nferromagnetic phase, magnetic states are frozen into the antiferromagnetic\nphase by the application of an electric field, thus eliminating the stray field\nand likewise making it insensitive to external magnetic field. Application of a\nreverse electric field reverts the antiferromagnetic state to the original\nferromagnetic state. Our work demonstrates the building blocks of a feasible,\nextremely stable, non-volatile, electrically addressable, low-energy\ndissipation, magnetoelectric multiferroic memory."
    },
    {
        "anchor": "Characterisation of slip and twinning in high rate deformed zirconium\n  with electron backscatter diffraction: Zirconium alloys are used in the nuclear industry as structural materials,\nand can be subject to high strain rate loading conditions during forming and in\nthe case of a reactor accident. In this context, the relationship between\nstrain rate dependent mechanical properties, crystallographic texture and\ndeformation modes, such as slip and deformation twinning, are explored in this\nwork. Commercially pure zirconium is deformed to 10 % engineering strain under\nquasi-static and high strain rate loading, and post-mortem analysis of the\nsamples is performed using electron backscatter diffraction (EBSD) to observe\ndifferent twin and slip systems activated. Twin types are identified from local\nintergranular misorientation maps, and active slip systems are identified from\nlong range intragranular misorientation maps. We link characterisation of the\nmechanical responses, twin types and morphologies, and relative slip system\nactivation as a function of loading mode. We find that variations in strength\nand hardening can be related to the relative propensity of twinning and the\nnumber of active slip systems.",
        "positive": "Analytical model for nonlinear response of carbon nanotubes enhanced by\n  a plasmonic metamaterial: We present an analytical model describing complex dynamics of a hybrid\nnonlinear system consisting of interacting carbon nanotubes (CNT) and a\nplasmonic metamaterial. Our model is based on the set of coupled equations,\nwhich incorporates well-established density matrix formalism appropriate for\nquantum systems (CNT are described as a two level system) and\nharmonic-oscillator approach ideal for modelling sub-wavelength plasmonic and\noptical resonators. We show that the saturation nonlinearity of CNT increases\nmultifold in the resonantly enhanced near field of a metamaterial. In the\nframework of our model, we discuss the effect of inhomogeneity of the CNT layer\n(band gap value distribution) on the nonlinearity enhancement. It is shown,\nthat the Purcell effect is indistinguishable from the field enhancement and is\ndescribed by the same phenomenological constant."
    },
    {
        "anchor": "Phase-field modelling and analysis of rate-dependent fracture phenomena\n  at finite deformation: Fracture of materials with rate-dependent mechanical behaviour, e.g.\npolymers, is a highly complex process. For an adequate modelling, the coupling\nbetween rate-dependent stiffness, dissipative mechanisms present in the bulk\nmaterial and crack driving force has to be accounted for in an appropriate\nmanner. In addition, the fracture toughness, i.e. the resistance against crack\npropagation, can depend on rate of deformation. In this contribution, an\nenergetic phase-field model of rate-dependent fracture at finite deformation is\npresented. For the deformation of the bulk material, a formulation of finite\nviscoelasticity is adopted with strain energy densities of Ogden type assumed.\nThe unified formulation allows to study different expressions for the fracture\ndriving force. Furthermore, a possibly rate-dependent toughness is\nincorporated. The model is calibrated using experimental results from the\nliterature for an elastomer and predictions are qualitatively and\nquantitatively validated against experimental data. Predictive capabilities of\nthe model are studied for monotonic loads as well as creep fracture.\nSymmetrical and asymmetrical crack patterns are discussed and the influence of\na dissipative fracture driving force contribution is analysed. It is shown\nthat, different from ductile fracture of metals, such a driving force is not\nrequired for an adequate simulation of experimentally observable crack paths\nand is not favourable for the description of failure in viscoelastic rubbery\npolymers. Furthermore, the influence of a rate-dependent toughness is discussed\nby means of a numerical study. From a phenomenological point of view, it is\ndemonstrated that rate-dependency of resistance against crack propagation can\nbe an essential ingredient for the model when specific effects such as\nrate-dependent brittle-to-ductile transitions shall be described.",
        "positive": "Simple route to Nd:YAG transparent ceramics: We report on the fabrication and spectroscopic characterization of\ntransparent Nd3+:YAG ceramic, a prospective material for future laser\napplications."
    },
    {
        "anchor": "Growth of high-quality CrI3 single crystals and engineering of its\n  magnetic properties via V and Mn doping: CrI3, as a soft van der Waals layered magnetic material, has been widely\nconcerned and explored for its magnetic complexity and tunability. In this\nwork, high quality and large size thin CrI3, V and Mn doped single crystals\nwere prepared by chemical vapor transfer method. A remarkable irreversible\nBarkhausen effect was observed in CrI3 and CrMn0.06I3, which can be attributed\nto the low dislocation density that facilitates movement of the domain walls.\nIn addition, the introduction of the doping element Mn allows higher saturation\nmagnetization intensity. Cr0.5V0.5I3 exhibits substantially increased\ncoercivity force and larger magnetocrystalline anisotropy compared to CrI3,\nwhile kept similar Curie temperature and good environmental stability. The\nfirst principles calculations suggest direct and narrowed band gaps in\nCr0.5V0.5I3 and VI3 comparing to CrI3. The smaller band gaps and good hard\nmagnetic property make Cr0.5V0.5I3 an alternative choice to future research of\nspintronic devices.",
        "positive": "Study of novel properties of graphene-ZnO heterojunction interface using\n  density functional theory: Studies of the structural, electronic, and optical characteristics of the\ninterfaces between graphene and ZnO polar surfaces is carried out using\nfirst-principles simulations. At the interface, a strong van der Waals force is\npresent, and because of the different work functions of graphene and ZnO,\ncharge transfer takes place. Graphene's superior conductivity is not impacted\nby its interaction with ZnO, since its Dirac point is unaffected despite its\nadsorption on ZnO. In hybrid systems, excited electrons with energies between 0\nand 3 eV (above Fermi energy) are primarily accumulated on graphene. The\ncalculations offer a theoretical justification for the successful operation of\ngraphene / ZnO hybrid materials as photocatalysts and solar cells. ZnO\nsemiconductor is found to be a suitable material with modest band gap, ($\\sim$\n3 eV), having high transparency in visible region and a high optical\nconductivity."
    },
    {
        "anchor": "Heat conductance is strongly anisotropic for pristine silicon nanowires: We compute atomistically the heat conductance for ultra-thin pristine silicon\nnanowires (SiNWs) with diameters ranging from 1 to 5 nm. The room temperature\nthermal conductance is found to be highly anisotropic: wires oriented along the\n<110> direction have 50-75% larger conductance than wires oriented along the\n<100> and <111> directions. We show that the anisotropies can be qualitatively\nunderstood and reproduced from the bulk phonon band structure. Ab initio\ndensity functional theory (DFT) is used to study the thinnest wires, but\nbecomes computationally prohibitive for larger diameters, where we instead use\nthe Tersoff empirical potential model (TEP). For the smallest wires, the\nthermal conductances obtained from DFT- and TEP calculations agree within 10%.\nThe presented results could be relevant for future phonon-engineering of\nnanowire devices.",
        "positive": "Transient grating spectroscopy on a DyCo$_5$ thin film with femtosecond\n  extreme ultraviolet pulses: Surface acoustic waves (SAWs) are excited by femtosecond extreme ultraviolet\n(EUV) transient gratings (TGs) in a room-temperature ferrimagnetic DyCo$_5$\nalloy. TGs are generated by crossing a pair of EUV pulses from a free electron\nlaser (FEL) with the wavelength of 20.8\\,nm matching the Co $M$-edge, resulting\nin a SAW wavelength of $\\Lambda=44$\\,nm. Using the pump-probe transient grating\nscheme in a reflection geometry the excited SAWs could be followed in the time\nrange of -10 to 100\\,ps in the thin film. Coherent generation of TGs by\nultrafast EUV pulses allows to excite SAW in any material and to investigate\ntheir couplings to other dynamics such as spin waves and orbital dynamics. In\ncontrast, we encountered challenges in detecting electronic and magnetic\nsignals, potentially due to the dominance of the larger SAW signal and the\nweakened reflection signal from underlying layers. A potential solution for the\nlatter challenge involves employing soft X-ray probes, albeit introducing\nadditional complexities associated with the required grazing incidence\ngeometry."
    },
    {
        "anchor": "Bayesian optimization of chemical composition: a comprehensive framework\n  and its application to $R$Fe$_{12}$-type magnet compounds: We propose a framework for optimization of the chemical composition of\nmultinary compounds with the aid of machine learning. The scheme is based on\nfirst-principles calculation using the Korringa-Kohn-Rostoker method and the\ncoherent potential approximation (KKR-CPA). We introduce a method for\nintegrating datasets to reduce systematic errors in a dataset, where the data\nare corrected using a smaller and more accurate dataset. We apply this method\nto values of the formation energy calculated by KKR-CPA for nonstoichiometric\nsystems to improve them using a small dataset for stoichiometric systems\nobtained by the projector-augmented-wave (PAW) method. We apply our framework\nto optimization of $R$Fe$_{12}$-type magnet compounds\n(R$_{1-\\alpha}$Z$_{\\alpha}$)(Fe$_{1-\\beta}$Co$_{\\beta}$)$_{12-\\gamma}$Ti$_{\\gamma}$,\nand benchmark the efficiency in determination of the optimal choice of elements\n(R and Z) and ratio ($\\alpha$, $\\beta$ and $\\gamma$) with respect to\nmagnetization, Curie temperature and formation energy. We find that the\noptimization efficiency depends on descriptors significantly. The variable\n$\\beta$, $\\gamma$ and the number of electrons from the R and Z elements per\ncell are important in improving the efficiency. When the descriptor is\nappropriately chosen, the Bayesian optimization becomes much more efficient\nthan random sampling.",
        "positive": "Density of states and electron concentration of double heterojunctions\n  subjected to an in-plane magnetic field: We calculate the electronic states of\nAl$_x$Ga$_{1-x}$As/GaAs/Al$_x$Ga$_{1-x}$As double heterojunctions subjected to\na magnetic field parallel to the quasi two-dimensional electron gas. We study\nthe energy dispersion curves, the density of states, the electron concentration\nand the distribution of the electrons in the subbands. The parallel magnetic\nfield induces severe changes in the density of states, which are of crucial\nimportance for the explanation of the magnetoconductivity in these structures.\nHowever, to our knowledge, there is no systematic study of the density of\nstates under these circumstances. We attempt a contribution in this direction.\nFor symmetric heterostructures, the depopulation of the higher subbands, the\ntransition from a single to a bilayer electron system and the domination of the\nbulk Landau levels in the centre the wide quantum well, as the magnetic field\nis continuously increased, are presented in the ``energy dispersion picture''\nas well as in the ``electron concentration picture'' and in the ``density of\nstates picture''."
    },
    {
        "anchor": "Strong Photoluminescence Enhancement of MoS2 through Defect Engineering\n  and Oxygen Bonding: We report on a strong photoluminescence (PL) enhancement of monolayer MoS2\nthrough defect engineering and oxygen bonding. Micro- PL and Raman images\nclearly reveal that the PL enhancement occurs at cracks/defects formed during\nhigh temperature vacuum annealing. The PL enhancement at crack/defect sites\ncould be as high as thousands of times after considering the laser spot size.\nThe main reasons of such huge PL enhancement include: (1) the oxygen chemical\nadsorption induced heavy p doping and the conversion from trion to exciton; (2)\nthe suppression of non-radiative recombination of excitons at defect sites as\nverified by low temperature PL measurements. First principle calculations\nreveal a strong binding energy of ~2.395 eV for oxygen molecule adsorbed on an\nS vacancy of MoS2. The chemical adsorbed oxygen also provides a much more\neffective charge transfer (0.997 electrons per O2) compared to physical\nadsorbed oxygen on ideal MoS2 surface. We also demonstrate that the defect\nengineering and oxygen bonding could be easily realized by oxygen plasma\nirradiation. X-ray photoelectron spectroscopy further confirms the formation of\nMo-O bonding. Our results provide a new route for modulating the optical\nproperties of two dimensional semiconductors. The strong and stable PL from\ndefects sites of MoS2 may have promising applications in optoelectronic\ndevices.",
        "positive": "Apparent Ferromagnetism in Exfoliated Ultra-thin Pyrite Sheets: Experimental evidence for ferromagnetic ordering in isotropic atomically thin\ntwo-dimensional crystals has been missing until a bilayer Cr2Ge2Te6, and a\nthree-atom thick monolayer CrI3 are shown to retain ferromagnetic ordering at\nfinite temperatures. Here, we demonstrate successful isolation of a non-van der\nWaals type ultra-thin nanosheet of FeS2 derived from naturally occurring pyrite\nmineral (FeS2) by means of liquid-phase exfoliation. Structural\ncharacterizations imply that (111) oriented sheets are predominant and is\nsupported theoretically by means of density functional theory surface energy\ncalculations. Spin-polarized density theory calculations further predicted that\n(111) oriented three-atom thick pyrite sheet has a stable ferromagnetic ground\nstate different from its diamagnetic bulk counterpart. This theoretical finding\nis evaluated experimentally employing low temperature superconducting quantum\ninterference device measurements and observed an anomalous ferromagnetic kind\nof behavior."
    },
    {
        "anchor": "On the equilibrium limit of liquid stability in pressurized aqueous\n  systems: Phase stability, and the limits thereof, are a central concern of materials\nthermodynamics. However, the temperature limits of equilibrium liquid stability\nin chemical systems have only been widely characterized under constant\n(typically atmospheric) pressure conditions, whereunder the limit is\nrepresented by the eutectic. At higher pressures, this limit will shift in both\ntemperature and chemical composition, opening a wide thermodynamic parameter\nspace over which the absolute limit, i.e., the limit under arbitrary values of\nthe thermodynamic forces at play (here pressure and concentration), might\nexist. In this work, we use isochoric freezing to measure this absolute limit\nfor the first time in several binary aqueous brines, and, nodding to the\netymology of \"eutectic\", we name this limit the \"cenotectic\" (from Greek \" \",\n\"universal-melt\"). We observe that when no solute-bearing high-pressure phases\nexist, the cenotectic occurs consistently 22 +/- 2K below the 1 bar eutectic\nand at approximately 213 +/- 3 MPa, suggesting domination by the liquidus\nbehaviors of the icy phases present. In charting the T-P evolution of each\neutectic configuration, we also encounter several unreported high-pressure\nhydrates of NaHCO2, MgCl2, and NaCl, and we find that these high-pressure\nphases can produce complex multi-phase configurations involving the liquid that\nmay remain metastable to significantly lower temperatures. We discuss the\nimplications of these findings for ocean worlds of our solar system and cold\nocean exoplanets; estimate thermodynamic limits on ice crust thickness and\nfinal ocean depth (\"endgame\") using the cenotectic pressure; and finally\nprovide a generalized thermodynamic perspective on (and definition for) this\nfundamental thermodynamic invariant point.",
        "positive": "The Effect of Shallow vs. Deep Level Doping on the Performance of\n  Thermoelectric Materials: It is well known that the efficiency of a good thermoelectric material should\nbe optimized with respect to doping concentration. However, much less attention\nhas been paid to the optimization of the dopant's energy level. Thermoelectric\nmaterials doped with shallow levels may experience a dramatic reduction in\ntheir figures of merit at high temperatures due to the excitation of minority\ncarriers that reduces the Seebeck coefficient and increases bipolar heat\nconduction. Doping with deep level impurities can delay the excitation of\nminority carriers as it requires a higher temperature to ionize all dopants. We\nfind through modeling that, depending on the material type and temperature\nrange of operation, different impurity levels (shallow or deep) will be desired\nto optimize the efficiency of a thermoelectric material. For different\nmaterials, we further clarify where the most preferable position of the\nimpurity level within the band gap falls. Our research provides insights in\nchoosing the most appropriate dopants for a thermoelectric material in order to\nmaximize the device efficiency."
    },
    {
        "anchor": "Ti-alloying of BaZrS3 chalcogenide perovskite for photovoltaics: BaZrS3, a prototypical chalcogenide perovskite, has been shown to possess a\ndirect band gap, an exceptionally strong near band edge light absorption, and\ngood carrier transport. Coupled with its great stability, non-toxicity with\nearth abundant elements, it is thus a promising candidate for thin film solar\ncells. However, its reported band gap in the range of 1.7-1.8 eV is larger than\nthe optimal value required to reach the Shockley-Queisser limit of a single\njunction solar cell. Here we report the synthesis of Ba(Zr1-xTix)S3 perovskite\ncompounds with a reduced band gap. It is found that Ti alloying is extremely\neffective in band gap reduction of BaZrS3: a mere 4 at% alloying decreases the\nband gap from 1.78 to 1.51 eV, resulting in a theoretical maximum power\nconversion efficiency of 32%. Higher Ti-alloying concentration is found to\ndestabilize the distorted chalcogenide perovskite phase.",
        "positive": "Multiphased alkali halide mixed crystals: The conductivity activation\n  energy: The preparation of mixed crystals of NaBr and KBr from melt as well as their\nphysical characterization have been reported. Electrical measurements were\ncarried out at various temperatures, which showed that their conductivity\nincreases with the increase in temperature and varies nonlinearly with the bulk\ncomposition. We find that for most of the compositions studied, the activation\nenergy deduced from the temperature variation of their conductivity obeys a\nthermodynamical model that interrelates the defect Gibbs energy with the bulk\nelastic and expansivity data."
    },
    {
        "anchor": "All-optical spin switching: A new frontier in femtomagnetism -- A short\n  review and a simple theory: Using an ultrafast laser pulse to manipulate the spin degree of freedom has\nbroad technological appeal. It allows one to control the spin dynamics on a\nfemtosecond time scale. The discipline, commonly called femtomagnetism, started\nwith the pioneering experiment by Beaurepaire and coworkers in 1996, who showed\nsubpicosecond demagnetization occurs in magnetic Ni thin films. This finding\nhas motivated extensive research worldwide. All-optical helicity-dependent spin\nswitching (AOS) represents a new frontier in femtomagnetism, where a single\nultrafast laser pulse can permanently switch spin without any assistance from a\nmagnetic field. This review summarizes some of the crucial aspects of this new\ndiscipline: key experimental findings, leading mechanisms, controversial\nissues, and possible future directions. The emphasis is on our latest\ninvestigation. We first develop the all-optical spin switching rule that\ndetermines how the switchability depends on the light helicity. This rule\nallows one to understand microscopically how the spin is reversed and why the\ncircularly polarized light appears more powerful than the linearly polarized\nlight. Then we invoke our latest spin-orbit coupled harmonic oscillator model\nto simulate single spin reversal. We consider both cw excitation and pulsed\nlaser excitation. The results are in a good agreement with the experimental\nresult. We then extend the code to include the exchange interaction among\ndifferent spin sites. We show where the \"inverse Faraday field\" comes from and\nhow the laser affects the spin reversal nonlinearly. Our hope is that this\nreview will motivate new experimental and theoretical investigations and\ndiscussions.",
        "positive": "Magneto-optics in transition metal diselenide monolayers: We perform photoluminescence experiments at 4K on two different transition\nmetal diselenide monolayers, namely MoSe2 and WSe2 in magnetic fields $B_z$ up\nto 9T applied perpendicular to the sample plane. In MoSe2 monolayers the valley\npolarization of the neutral and the charged exciton (trion) can be tuned by the\nmagnetic field, independent of the excitation laser polarization. In the\ninvestigated WSe2 monolayer sample the evolution of the trion valley\npolarization depends both on the applied magnetic field and the excitation\nlaser helicity, while the neutral exciton valley polarization depends only on\nthe latter. Remarkably we observe a reversal of the sign of the trion\npolarization between WSe2 and MoSe2. For both systems we observe a clear Zeeman\nsplitting for the neutral exciton and the trion of about $\\pm2$meV at\n$B_z\\mp9$T. The extracted Land\\'{e}-factors for both exciton complexes in both\nmaterials are $g\\approx -4$."
    },
    {
        "anchor": "E-beam-enhanced solid-state mechanical amorphization of alpha-quartz:\n  Reducing deformation barrier via localized excess electrons as mobile anions: Under hydrostatic pressure, alpha-quartz undergoes solid-state mechanical\namorphization wherein the interpenetration of SiO4 tetrahedra occurs and the\nmaterial loses crystallinity. This phase transformation requires a high\nhydrostatic pressure of 14 GPa because the repulsive forces resulting from the\nionic nature of the Si-O bonds prevent the severe distortion of the atomic\nconfiguration. Herein, we experimentally and computationally demonstrate that\ne-beam irradiation changes the nature of the interatomic bonds in alpha-quartz\nand enhances the solid-state mechanical amorphization at nanoscale.\nSpecifically, during in situ uniaxial compression, a larger permanent\ndeformation occurs in alpha-quartz micropillars compressed during e-beam\nirradiation than in those without e-beam irradiation. Microstructural analysis\nreveals that the large permanent deformation under e-beam irradiation\noriginates from the enhanced mechanical amorphization of alpha-quartz and the\nsubsequent viscoplastic deformation of the amorphized region. Further,\natomic-scale simulations suggest that the delocalized excess electrons\nintroduced by e-beam irradiation move to highly distorted atomic configurations\nand alleviate the repulsive force, thus reducing the barrier to the solid-state\nmechanical amorphization. These findings deepen our understanding of\nelectron-matter interactions and can be extended to new glass forming and\nprocessing technologies at nano- and microscale.",
        "positive": "Ti-rich and Cu-poor grain-boundary layers of CaCu$_3$Ti$_4$O$_{12}$\n  detected by x-ray photoelectron spectroscopy: Cleaved and polished surfaces of CaCu$_3$Ti$_4$O$_{12}$ ceramics have been\ninvestigated by x-ray photoelectron spectroscopy (XPS) and energy dispersive\nx-ray spectroscopy (EDX), respectively. While EDX technique shows the identical\nCaCu$_3$Ti$_4$O$_{12}$ stoichiometry for the two surfaces, XPS indicates that\nthe cleaved surface with grain-boundary layers is remarkably Ti-rich and\nCu-poor. The core-level spectrum of Cu 2$p$ unambiguously shows the existence\nof monovalent copper only for the cleaved surface. Possible grain-boundary\nstructure and its formation are discussed."
    },
    {
        "anchor": "Possibility of the investigation of the X-ray diffraction patterns for\n  yttrium ceramic YBa2Cu3Ox having different oxygen stoichiometry on the basis\n  of the mixed-layer crystal model: In view of the strong anisotropy of oxygen diffusion in high-Tc ceramic\nYBa2Cu3Ox, it is supposed that a polycrystalline sample of this material can be\npresented as consisting of crystal grains where each grain was formed by a\ncertain sequence of layers with tetragonal or orthorhombic phase structure. The\ntheory of scattering by mixed-layer crystals was taken as a basis for\ncalculating theoretical X-ray patterns for different sequences of the layers.\nSome modifications were made in the theory due to crystal structure features of\nthe YBa2Cu3Ox phases. The results obtained agreed quantitatively with data\npublished in many papers and can be used for interpreting the X-ray patterns\nfrom ceramics with different oxygen stoichiometry.",
        "positive": "The RKKY coupling in diluted magnetic semiconductors: This paper is an attempt to modify the classic Ruderman-Kittel-Kasuya-Yosida\n(RKKY) model to allow the analysis of the magnetic resonance measurements. In\nour calculations, we follow the treatment of the original authors of the RKKY\nmodel but include the finite band splitting, {\\Delta}, as a phenomenological\nparameter. The RKKY exchange is not anymore of Heisenberg type and an\nanisotropy induced by the direction of carrier magnetization occurs."
    },
    {
        "anchor": "Quantum Effects of Strain Influence on the Doping Energy in\n  Semiconductors: Applying external strain is an efficient way to manipulate the site\npreference of dopants in semiconductors, however, the validity of the previous\ncontinuum elastic model for the strain influence on the doping forma- tion\nenergy is still under debate. In this paper, by combining quantum mechanical\ntheoretical analysis and first-principles calculations, we show that if the\noccupation change of different orbitals caused by the strain is negligible, the\ncontinuum elastic model is valid, otherwise it will fail. Our theory is\nconfirmed by first-principles calculation of Mn-doped GaAs system. Moreover, we\nshow that under compressive strain the hole density, thus the Curie temperature\nTC can increase in Mn-doped spintronic materials.",
        "positive": "Barkhausen Noise Probe of the Ferroelectric Transition in the Relaxor\n  PbMg1/3Nb2/3O3-12% PbTiO3: Barkhausen current noise is used to probe the slow field-driven conversion of\nthe glassy relaxor ferroelectric state to an ordered ferroelectric (FE) state.\nThe frequent presence of distinct micron-scale Barkhausen events well before\nthe polarization current starts to speed up shows that the process is not a\nconventional nucleation-limited one. The prevalence of reverse switching events\nnear the onset of the rapid part of the transition strongly indicates that\nelectric dipole interactions play a key role. The combination of Barkhausen\nnoise changes and changes in the complex dielectric response indicate that the\nprocess consists of an initial mixed-alignment domain formation stage followed\nby growth of the domains aligned with the applied field."
    },
    {
        "anchor": "Electric-Field Tuning of Spin-Dependent Exciton-Exciton Interactions in\n  Coupled Quantum Wells: We have shown experimentally that an electric field decreases the energy\nseparation between the two components of a dense spin-polarized exciton gas in\na coupled double quantum well, from a maximum splitting of $\\sim 4$ meV to\nzero, at a field of $\\sim $35 kV/cm. This decrease, due to the field-induced\ndeformation of the exciton wavefunction, is explained by an existing\ncalculation of the change in the spin-dependent exciton-exciton interaction\nwith the electron-hole separation. However, a new theory that considers the\nmodification of screening with that separation is needed to account for the\nobserved dependence on excitation power of the individual energies of the two\nexciton components.",
        "positive": "O$_2$ on Ag(110): A puzzle for exchange-correlation functionals: Despite the great success of density functional theory in describing\nmaterials, there are still a few examples where current exchange-correlation\nfunctionals fail. We add another example to this list that drives further\ndevelopment of functionals. We show that the interaction of O$_2$ with Ag(110)\ncannot be properly described by some of the most popular GGA, meta GGA, and\nhybrid functionals. We identify problems and provide clues for a functional\nthat should be able to describe this and similar systems properly."
    },
    {
        "anchor": "Spin-torque induced wall motion in perpendicularly magnetized discs:\n  ballistic versus oscillatory behavior: We use time-resolved measurement and modeling to study the spin-torque\ninduced motion of a domain wall in perpendicular anisotropy magnets. In disc of\ndiameters between 70 and 100 nm, the wall drifts across the disc with\npronounced back-and-forth oscillations that arise because the wall moves in the\nWalker regime. Several switching paths occur stochastically and lead to\ndistinct switching durations. The wall can cross the disc center either in a\nballistic manner or with variably marked oscillations before and after the\ncrossing. The crossing of the center can even occur multiple times if a\nvertical Bloch line nucleates within the wall. The wall motion is analyzed\nusing a collective coordinate model parametrized by the wall position $q$ and\nthe tilt $\\phi$ of its in-plane magnetization projection. The dynamics results\nfrom the stretch field, which describes the affinity of the wall to reduce its\nlength and the wall stiffness field describing the wall tendency to reduce\ndipolar energy by rotating its tilt. The wall oscillations result from the\ncontinuous exchange of energy between to the two degrees of freedom $q$ and\n$\\phi$. The stochasticity of the wall dynamics can be understood from the\nconcept of the retention pond: a region in the $q-\\phi$ space in which walls\nare transiently bound to the disc center. Walls having trajectories close to\nthe pond must circumvent it and therefore have longer propagation times. The\nretention pond disappears for a disc diameter of typically 40 nm: the wall then\nmoves in a ballistic manner irrespective of the dynamics of its tilt. The\npropagation time is then robust against fluctuations hence reproducible.",
        "positive": "Modeling of hysteresis phenomena in crystalline ferroelectrics:\n  hysteresis loops shape control by means of electric field parameters: Description of domains switching processes in crystalline ferroelectrics by\nmeans of relaxation type equations with account of variable external electric\nfield is proposed. Exact solution of these equations in closed analytical form\nat arbitrary dependence of electric field on time is obtained. A connection\nbetween frequency of sinusoidal external field and hysteresis loops shapes is\nanalysed by numerical way. The calculation results are in qualitative\naccordance with experimental data.\n  PACS: 77.80.Fm, 77.80.Dj, 77.80.-e\n  Keywords: ferroelectrics, switching process, hysteresis, polarization"
    },
    {
        "anchor": "Polarization states of polydomain epitaxial Pb(Zr1-xTix)O3 thin films\n  and their dielectric properties: Ferroelectric and dielectric properties of polydomain (twinned)\nsingle-crystal Pb(Zr1-xTix)O3 thin films are described with the aid of a\nnonlinear thermodynamic theory, which has been developed recently for epitaxial\nferroelectric films with dense laminar domain structures. For Pb(Zr1-xTix)O3\n(PZT) films with compositions x = 0.9, 0.8, 0.7, 0.6, 0.5, and 0.4, the \"misfit\nstrain-temperature\" phase diagrams are calculated and compared with each other.\nIt is found that the equilibrium diagrams of PZT films with x > 0.7 are similar\nto the diagram of PbTiO3 films. They consist of only four different stability\nranges, which correspond to the paraelectric phase, single-domain tetragonal\nferroelectric phase, and two pseudo-tetragonal domain patterns. In contrast, at\nx = 0.4, 0.5, and 0.6, the equilibrium diagram displays a rich variety of\nstable polarization states, involving at least one monoclinic polydomain state.\nUsing the developed phase diagrams, the mean out-of-plane polarization of a\npoled PZT film is calculated as a function of the misfit strain and\ncomposition. Theoretical results are compared with the measured remanent\npolarizations of PZT films grown on SrTiO3. Dependence of the out-of-plane\ndielectric response of PZT films on the misfit strain in the heterostructure is\nalso reported.",
        "positive": "Ab Initio Modeling of Thermal Transport through van der Waals Materials: An advanced modeling approach is presented to shed light on the thermal\ntransport properties of van der Waals materials (vdWMs) composed of\nsingle-layer transition metal dichalcogenides (TMDs) stacked on top of each\nother with a total or partial overlap only in the middle region. It relies on\nthe calculation of dynamical matrices from first-principle and on their usage\nin a phonon quantum transport simulator. We observe that vibrations are\ntransferred microscopically from one layer to the other along the overlap\nregion which acts as a filter selecting out the states that can pass through\nit. Our work emphasizes the possibility of engineering heat flows at the\nnanoscale by carefully selecting the TMD monolayers that compose vdWMs."
    },
    {
        "anchor": "Random telegraph noise from magnetic nanoclusters in the ferromagnetic\n  semiconductor (Ga,Mn)As: Measurements of the low frequency electrical noise in the ferromagnetic\nsemiconductor (Ga,Mn)As reveal an enhanced integrated noise at low temperature.\nFor moderate localization, we find a 1/f normalized power spectrum density over\nthe entire range of temperatures studied (4.2K < T < 70K). However, for\nstronger localization and a high density of Mn interstitials, we observe\nLorentzian noise spectra accompanied by random telegraph noise. Magnetic field\ndependence and annealing studies suggest that interstitial Mn defects couple\nwith substitutional Mn atoms to form nanoscale magnetic clusters characterized\nby a net moment of about 20 Bohr magnetons whose fluctuations modulate hole\ntransport.",
        "positive": "Dirac surface states in intrinsic magnetic topological insulators\n  EuSn2As2 and MnBi2nTe3n+1: In magnetic topological insulators (TIs), the interplay between magnetic\norder and nontrivial topology can induce fascinating topological quantum\nphenomena, such as the quantum anomalous Hall effect, chiral Majorana fermions\nand axion electrodynamics. Recently, a great deal of attention has been focused\non the intrinsic magnetic TIs, where disorder effects can be eliminated to a\nlarge extent, which is expected to facilitate the emergence of topological\nquantum phenomena. In despite of intensive efforts, experimental evidence of\nthe topological surface states (SSs) remains elusive. Here, by combining\nfirst-principles calculations and angle-resolved photoemission spectroscopy\n(ARPES) experiments, we have revealed that EuSn2As2 is an antiferromagnetic TI\nwith observation of Dirac SSs consistent with our prediction. We also observe\nnearly gapless Dirac SSs in antiferromagnetic TIs MnBi2nTe3n+1 (n = 1 and 2),\nwhich were absent in previous ARPES results. These results provide clear\nevidence for nontrivial topology of these intrinsic magnetic TIs. Furthermore,\nwe find that the topological SSs show no observable changes across the magnetic\ntransition within the experimental resolution, indicating that the magnetic\norder has quite small effect on the topological SSs, which can be attributed to\nweak hybridization between the localized magnetic moments, from either 4f or 3d\norbitals, and the topological electronic states. This provides insights for\nfurther research that the correlations between magnetism and topological states\nneed to be strengthened to induce larger gaps in the topological SSs, which\nwill facilitate the realization of topological quantum phenomena at higher\ntemperatures."
    },
    {
        "anchor": "Discovery of Ordered Vortex Phase in Multiferroic Oxide Superlattices: Ferroics, characterized by a broken symmetry state with nonzero elastic,\npolar, or magnetic order parameters $\\vec{u}$, are recognized platforms for\nstaging and manipulating topologically-protected structures as well as for\ndetecting unconventional topological phenomena. The unrealized possibility of\nproducing ordered topological phases in magnetoelectric multiferroics,\nexhibiting coupled magnetic and polar order parameters, is anticipated to\nengender novel functionality and open avenues for manipulating topological\nfeatures. Here, we report the discovery of an ordered $\\pi_1$-$S_\\infty$ vortex\nphase within single-phase magnetoelectric multiferroic BiFeO$_3$. The phase,\ncharacterized by positive topological charge and chiral staggering, is realized\nin coherent TbScO$_3$ and BiFeO$_3$ superlattices and established via the\ncombination of direct- and Fourier-space analyses. Observed order-parameter\nmorphologies are reproduced with a field model describing the local\norder-parameter stiffness and competing non-local dipole-dipole interactions.\nAnisotropies canting the order parameter towards $\\left<100\\right>$ suppress\nchiral staggering and produced a competing $\\pi_1$-$C_{\\infty v}$ vortex phase\nin which cores are centered.",
        "positive": "Magnetism of noncolinear amorphous DyCo3 and TbCo3 thin films: The magnetization of amorphous DyCo3 and TbCo3 is studied by magnetometry,\nanomalous Hall effect and magneto-optic Kerr effect to understand the\ntemperature-dependent magnetic structure. A square magnetic hysteresis loop\nwith perpendicular magnetic anisotropy and coercivity that reaches 3.5 T in the\nvicinity of the compensation temperature is seen in thin films. An anhysteretic\nsoft component, seen in the magnetization of some films but not in their Hall\nor Kerr loops is an artefact due to sputter-deposition on the sides of the\nsubstrate. The temperature-dependence of the net rare earth moment from 4-300K\nis deduced, using the cobalt moment in amorphous YxCo1-x. The single-ion\nanisotropy of the quadrupole moments of the 4f atoms in the randomly-oriented\nlocal electrostatic field gradient overcomes their exchange coupling to the\ncobalt subnetwork, resulting in a sperimagnetic ground state where spins of the\nnoncollinear rare-earth subnetwork are modelled by a distribution of rare earth\nmoments within a cone whose axis is antiparallel to the ferromagnetic axis z of\nthe cobalt subnetwork. The reduced magnetization (Jz)/J at T=0 is calculated\nfrom an atomic Hamiltonian as a function of the ratio of anisotropy to exchange\nenergy per rare-earth atom for a range of angles between the local anisotropy\naxis and -z and then averaged over all directions in a hemisphere. The\nexperimental and calculated values of (J-z)/J are close to 0.7 at low\ntemperature for both Dy and Tb. On increasing temperature, the magnitude of the\nrare earth moment and the local random anisotropy that creates the cone are\nreduced; the cone closes and the structure approaches collinear ferrimagnetism\nwell above ambient temperature. An asymmetric spin flop of the exchange-coupled\nsubnetworks appears in the vicinity of the magnetization compensation\ntemperatures of 175K for amorphous Dy0.25Co0.75 and 200 K for amorphous TbCo3."
    },
    {
        "anchor": "Rules of plastic strain-induced phase transformations and nanostructure\n  evolution under high-pressure and severe plastic flow: Rough diamond anvils (rough-DA) are introduced to intensify all occurring\nprocesses during an in-situ study of heterogeneous compression of strongly\npre-deformed Zr in diamond anvil cell (DAC). Crystallite size and dislocation\ndensity of Zr are getting pressure-, plastic strain tensor- and\nstrain-path-independent during {\\alpha}-{\\omega} phase transformation (PT) and\ndepend solely on the volume fraction of {\\omega}-Zr. Rough-DA produce a steady\nnanostructure in {\\alpha}-Zr with lower crystallite size and larger dislocation\ndensity than smooth-DA, leading to a two-time reduction in a minimum pressure\nfor {\\alpha}-{\\omega} PT to a record value 0.67 GPa. The kinetics of\nstrain-induced PT unexpectedly depends on time.",
        "positive": "Rigidity of the conductance of anchored dithioazobenzene opto-mechanical\n  switch: Reversible opto-mechanical molecular switch based on a single azobenzene\nmolecule suspended via thiolate links between realistic models of gold tips is\ninvestigated. Using a combination of the transfer matrix technique and density\nfunctional theory we focus on conductance of the nano-device in the two\n(meta)stable cis and trans junction conformations. We find the conductance of\nboth conformations to be broadly similar. In qualitative agreement with related\nexperiments, we find that the same nano-device with one/two methylene linker\ngroup(s) inserted on one/both ends of the azobenzene molecule is driven into\ntunneling regime and reduces the conductances by up to two orders of magnitude,\nagain almost uniformly for both conformations. These results clarify the huge\ndifferences in switching ratios found previously and indicate that this\nnano-device is not particularly suited for use as a molecular switch based on\nconductance change."
    },
    {
        "anchor": "Carrier doping to pseudo-low-dimensional compound La2RuO5: Hole carrier doping has been tried to pseudo-low-dimensional material La2RuO5\nby substituting La3+ with Cd2+. Single phased samples of La2-xCdxRuO5 with x up\nto 0.5 have been successfully obtained and also high pressure O2 annealing has\nbeen performed to the x=0.5 sample. Although the formal ionic state of Ru is\nexpected to increase from 4+ (at x=0) to 4.5+ (at x=0.5), the magnetic and\nelectrical properties show no significant changes in as-sintered samples. In\ncontrast, high pressure O2 annealed x=0.5 samples show a little reduction of\nelectrical resistivity and the decrease of thermoelectric power at 260 K. From\nthese results, it can be speculated that the doped carriers are mostly\ncompensated by oxygen deficiency in as-sintered samples.",
        "positive": "Ge clusters and wetting layers forming from granular films on the\n  Si(001) surface: The report studies transformation of a Ge granular film deposited at room\ntemperature on the Si(001) surface to the Ge/Si(001) heterostructure as a\nresult of rapid heating and annealing at 600C. As a result of the short-term\nannealing at 600C in conditions of a closed system, the Ge granular film\ntransforms to the usual wetting layer and Ge clusters with multimodal size\ndistribution and the Ge oval drops having the highest number density. After the\nlong-term thermal treatment of the Ge film at the same temperature, Ge drops\ndisappear; the large clusters increase their sizes at the expense of the\nsmaller ones. The total density of Ge clusters on the surface drastically\ndecreases. The wetting layer mixed c(4 x 2) + p(2 x 2) reconstruction\ntransforms to the single c(4 x 2) one which is likely thermodynamically\nfavoured. Pyramids or domes are not observed on the surface after any\nannealing."
    },
    {
        "anchor": "Systematic study of defect-related quenching of NV luminescence in\n  diamond with time correlated single photon counting spectroscopy: We report on the systematic characterization of photoluminescence (PL)\nlifetimes in NV- and NV0 centers in 2 MeV H+ implanted type Ib diamond samples\nby means of a time correlated single photon counting (TCSPC) microscopy\ntechnique. A dipole-dipole resonant energy transfer model was applied to\ninterpret the experimental results, allowing a quantitative correlation of the\nconcentration of both native (single substitutional nitrogen atoms) and\nion-induced (isolated vacancies) PL-quenching defects with the measured PL\nlifetimes. The TCSPC measurements were carried out in both frontal (i.e. laser\nbeam probing the main sample surface along the same normal direction of the\npreviously implanted ions) and lateral (i.e. laser beam probing the lateral\nsample surface orthogonally with respect to the same ion implantation\ndirection) geometries. In particular, the latter geometry allowed a direct\nprobing of the centers lifetime along the strongly nonuniform damage profiles\nof MeV ions in the crystal. The extrapolation of empirical quasi-exponential\ndecay parameters allowed the systematic estimation of the mean quantum\nefficiency of the centers as a function of intrinsic and ion-induced defect\nconcentration, which is of direct relevance for the current studies on the use\nof diamond color centers for photonic applications.",
        "positive": "Structural and Dielectric Characterization on Multiferroic\n  xNi0.9Zn0.1Fe2O4/(1-x)PbZr0.52Ti0.48O3 Particulate Composite: We have carried out the powder x-ray diffraction and dielectric studies on\nmultiferroic particulate composite xNi0.9Zn0.1Fe2O4/(1-x)PbZr0.52Ti0.48O3 with\nx=0.15, 0.30, 0.45, 0.60, 0.75 and 0.90 to explore the structural and\nferroelectric properties. A conventional double sintering method was used to\nprepare the xNi0.9Zn0.1Fe2O4/(1-x)PbZr0.52Ti0.48O3 composites. The structure of\none of the component Ni0.9Zn0.1Fe2O4 is spinel cubic with space group Fd3m,\nwhile the other component PbZr0.52Ti0.48O3 is selected around the morphotropic\nphase boundary region in which the tetragonal and monoclinic phases with space\ngroup P4mm and Cm coexist respectively. We have carried out Rietveld refinement\nof the structure to check the formation of ideal composites with separate\nferroelectric and ferrite phases. Even though the structural characterization\ndoes not reveal the formation of any new phase due to reaction between the two\ncomponents of the composite during sintering, the tetragonality of the\nPbZr0.52Ti0.48O3 continuously decreases with increasing the ferrite fraction\nwhile the lattice parameter of ferrite phase increases with increasing fraction\nof the ferroelectric phase. Similarly, the dielectric study reveals clear shift\nin the ferroelectric to paraelectric phase transition temperature of\nPbZr0.52Ti0.48O3 during composite formation suggesting that part of Ni2+, Zn2+/\nFe3+ ions are diffusing at the B-site of PbZr0.52Ti0.48O3 replacing Ti4+, which\nin turn decreases its transition temperature. Scanning electron micrograph of\nsintered pellet surface confirms the presence of two types of particle\nmorphology in the particulate composite, corresponding to ferrite and\nferroelectric phases."
    },
    {
        "anchor": "Fermi Surfaces and $p$-$d$ Hybridization in the Diluted Magnetic\n  Semiconductor Ba$_{1-x}$K$_{x}$(Zn$_{1-y}$Mn$_{y}$)$_{2}$As$_{2}$ Studied by\n  Soft X-ray Angle Resolved Photoemission Spectroscopy: The electronic structure of the new diluted magnetic semiconductor\nBa$_{1-x}$K$_{x}$(Zn$_{1-y}$Mn$_{y}$)$_{2}$As$_{2}$ ($x=0.30$, $y=0.15$) in\nsingle crystal form has been investigated by angle-resolved photoemission\nspectroscopy (ARPES). %High density of states of nondispersive bands composed\nof the Zn $3d$ orbitals are observed with ultraviolet incident light.\nMeasurements with soft x-rays clarify the host valence-band electronic\nstructure primarily composed of the As $4p$ states. Two hole pockets around the\n$\\Gamma$ point, a hole corrugated cylinder surrounding the $\\Gamma$ and Z\npoints, and an electron pocket around the Z point are observed, and explain the\nmetallic transport of Ba$_{1-x}$K$_{x}$(Zn$_{1-y}$Mn$_{y}$)$_{2}$As$_{2}$. This\nis contrasted with Ga$_{1-x}$Mn$_{x}$As (GaMnAs), where it is located above the\nAs $4p$ valence-band maximum (VBM) and no Fermi surfaces have been clearly\nidentified. Resonance soft x-ray ARPES measurements reveal a nondispersive\n(Kondo resonance-like) Mn $3d$ impurity band near the Fermi level, as in the\ncase of GaMnAs. However, the impurity band is located well below the VBM,\nunlike the impurity band in GaMnAs, which is located around and above the VBM.\nWe conclude that, while the strong hybridization between the Mn $3d$ and the As\n$4p$ orbitals plays an important role in creating the impurity band and\ninducing high temperature ferromagnetism in both systems, the metallic\ntransport may predominantly occur in the host valence band in\nBa$_{1-x}$K$_{x}$(Zn$_{1-y}$Mn$_{y}$)$_{2}$As$_{2}$ and in the impurity band in\nGaMnAs.",
        "positive": "The electronic structure of GaN and Ga investigated by soft x-ray\n  spectroscopy and first-principles methods: The electronic structure and chemical bonding of wurtzite-GaN investigated by\nN 1s soft x-ray absorption spectroscopy and N K, Ga M1, and Ga M2,3 emission\nspectroscopy is compared to that of pure Ga. The measurements are interpreted\nby calculated spectra using first-principles density-functional theory (DFT)\nincluding dipole transition matrix elements and additional on-site Coulomb\ninteraction (WC-GGA+U). The Ga 4p - N 2p and Ga 4s - N 2p hybridization and\nchemical bond regions are identified at the top of the valence band between\n-1.0 and -2.0 and further down between -5.5 and -6.5 eV, respectively. In\naddition, N 2s - N 2p - Ga 4s and N 2s - N 2p - Ga 3d hybridization regions\noccur at the bottom of the valence band between -13 and -15 eV, and between\n-17.0 and -18.0 eV, respectively. A band-like satellite feature is also found\naround -10 eV in the Ga M1 and Ga M2,3 emission from GaN, but is absent in pure\nGa and the calculated ground state spectra. The difference between the\nidentified spectroscopic features of GaN and Ga are discussed in relation to\nthe various hybridization regions calculated within band-structure methods."
    },
    {
        "anchor": "Magnetic relaxation phenomena in the Chiral Magnet Fe$_{1-x}$Co$_x$Si:\n  An ac susceptibility study: We present a systematic study of the ac susceptibility of the chiral magnet\nFe$_{1-x}$Co$_x$Si with $x$ = 0.30 covering four orders of magnitude in\nfrequencies from 0.1 Hz to 1 kHz, with particular emphasis to the pronounced\nhistory dependence. Characteristic relaxation times ranging from a few\nmilliseconds to tens of seconds are observed around the skyrmion lattice\nA-phase, the helical-to-conical transition and in a region above $T_C$. The\ndistribution of relaxation frequencies around the A-phase is broad, asymmetric\nand originates from multiple coexisting relaxation processes. The pronounced\ndependence of the magnetic phase diagram on the magnetic history and cooling\nrates as well as the asymmetric frequency dependence and slow dynamics suggest\nmore complicated physical phenomena in Fe$_{0.7}$Co$_{0.3}$Si than in other\nchiral magnets.",
        "positive": "Negative Poisson's Ratio in Single-Layer Black Phosphorus: The Poisson's ratio is a fundamental mechanical property that relates the\nresulting lateral strain to applied axial strain. While this value can\ntheoretically be negative, it is positive for nearly all materials, though\nnegative values have been observed in so-called auxetic structures. However,\nnearly all auxetic materials are bulk materials whose microstructure has been\nspecifically engineered to generate a negative Poisson's ratio. In the present\nwork, we report using first principles calculations the existence of a negative\nPoisson's ratio in a single-layer, two-dimensional material, black phosphorus.\nIn contrast to engineered bulk auxetics, this behavior is intrinsic for single\nlayer black phosphorus, and originates from its unique, puckered structure,\nwhere the pucker can be regarded as a re-entrant structure that is comprised of\ntwo coupled orthogonal hinges. As a result of this atomic structure, a negative\nPoisson's ratio is observed in the out-of-plane direction under uniaxial\ndeformation in the direction parallel to the pucker, with the Poisson's ratio\nbecoming increasingly negative with both increased tension and compression. The\npuckered structure also results in highly anisotropic in-plane Poisson's\nratios, which are found to be 0.4 in the direction perpendicular and 1.28 in\nthe direction parallel to the pucker."
    },
    {
        "anchor": "Temperature-Dependent In-Situ LEIS Measurement of W Surface Enrichment\n  by 250 eV D Sputtering of EUROFER: Tungsten surface enrichment of EUROFER steel by 250 eV deuterium sputtering\nis in-situ measured using low energy He$^{+}$ ion scattering spectroscopy. The\nsamples are irradiated at various temperatures between 300 K and 800 K with a\ndeuterium atom flux of 2e18 m$^{-2}$s$^{-1}$ and maximum fluence up to 1.1e23\nm$^{-2}$. The measurements at room temperature show a clear increase of\ntungsten surface density, but already at 520 K the observed enrichment is only\nhalf as large. At a temperature of 800 K no tungsten surface enrichment is\ndetectable. The obtained data allows to determine an upper limit of 1.6 eV for\nthe diffusion activation energy of tungsten in EUROFER.",
        "positive": "Ab initio study of proton-exchanged LiNbO3(I): Structural,\n  thermodynamic, dielectric, and optical properties: Using first principles calculations, we study the ground-state structure of\nbulk proton-exchanged lithium niobate, which is also called hydrogen niobate\nand is widely used in waveguides. Thermodynamics helps to establish the most\nfavorable nonpolar surface as well as the water-deficient and water-rich phases\nunder different ambient conditions, which we refer to as \"dehydrated\" and\n\"rehydrated\" phases, respectively. We compute the low-frequency dielectric\nresponse and the optical refractive indices of hydrogen niobate in different\nphases. The dielectric constant is greatly enhanced compared to lithium\nniobate. At shorter wavelengths, the refractive indices vary between each phase\nand have a sharp contrast to lithium niobate. Our study characterizes the\nstructures and thermal instabilities of this compound and reveals its excellent\ndielectric and optical properties, which can be important in the future\napplication in waveguides."
    },
    {
        "anchor": "Colossal Thermoelectric Power Factor in K$_{7/8}$RhO$_2$: We discuss the thermoelectric and optical properties of layered\nK$_{x}$RhO$_{2}$ (\\emph{x} = 1/2 and 7/8) in terms of the electronic structure\ndetermined by first principles calculations as well as Boltzmann transport\ntheory. Our optimized lattice constants differ significantly from the\nexperiment, but result in optical and transport properties close to the\nexperiment. The main contribution to the optical spectra are due to intra and\ninter-band transitions between the Rh 4\\emph{d} and O 2\\emph{p} states. We find\na similar power factor for pristine K$_{x}$RhO$_{2}$ at low and high cation\nconcentartions. Our transport results of hydrated K$_{x}$RhO$_{2}$ at room\ntemperature show highest value of the power factor among the hole-type\nmaterials. Specially at 100 K, we obtain a value of 3$\\times$10$^{-3}$ K$^{-1}$\nfor K$_{7/8}$RhO$_{2}$, which is larger than that of Na$_{0.88}$CoO$_{2}$ {[}M.\nLee \\emph{et al}., Nat. Mater. 5, 537 (2006){]}. In general, the electronic and\noptical properties of K$_{x}$RhO$_{2}$ are similar to Na$_{x}$CoO$_{2}$ with\nenhanced transport properties in the hydrated phase.",
        "positive": "Composition-dependent magnetic response properties of Mn$_{1-x}$Fe$_x$Ge\n  alloys: The composition-dependent behavior of the Dzyaloshinskii-Moriya interaction\n(DMI), the spin-orbit torque (SOT), as well as anomalous and spin Hall\nconductivities of Mn$_{1-x}$Fe$_x$Ge alloys have been investigated by\nfirst-principles calculations using the relativistic multiple scattering\nKorringa-Kohn-Rostoker (KKR) formalism. The $D_{\\rm xx}$ component of the DMI\nexhibits a strong dependence on the Fe concentration, changing sign at $x\n\\approx 0.85$ in line with previous theoretical calculations as well as with\nexperimental results demonstrating the change of spin helicity at $x \\approx\n0.8$. A corresponding behavior with a sign change at $x \\approx 0.5$ is\npredicted also for the Fermi sea contribution to the SOT, as this is closely\nrelated to the DMI. In the case of anomalous and spin Hall effects it is shown\nthat the calculated Fermi sea contributions are rather small and the\ncomposition-dependent behavior of these effects are determined mainly by the\nelectronic states at the Fermi level. The spin-orbit-induced scattering\nmechanisms responsible for both these effects suggest a common origin of the\nminimum of the AHE and the sign change of the SHE conductivities."
    },
    {
        "anchor": "Optical Properties of GaS-Ca(OH)$_2$ bilayer heterostructure: Finding novel atomically-thin heterostructures and understanding their\ncharacteristic properties are critical for developing better nanoscale\noptoelectronic devices. In this study, we investigate the electronic and\noptical properties of GaS-Ca(OH)$_2$ heterostructure using first-principle\ncalculations. The band gap of the GaS-Ca(OH)$_2$ heterostructure is\nsignificantly reduced when compared with those of the isolated constituent\nlayers. Our calculations show that the GaS-Ca(OH)$_2$ heterostructure is a\ntype-II heterojunction which can be used to separate photoinduced charge\ncarriers where electrons are localized in GaS and holes in the Ca(OH)$_2$\nlayer. This leads to spatially indirect excitons which are important for solar\nenergy and optoelectronic applications due to their long lifetime. By solving\nthe Bethe-Salpeter equation on top of single shot GW calculation (G$_0$W$_0$)\nthe dielectric function and optical oscillator strength of the constituent\nmonolayers and the heterostructure are obtained. The oscillator strength of the\noptical transition for GaS monolayer is an order of magnitude larger than\nCa(OH)$_2$ monolayer. We also found that the calculated optical spectra of\ndifferent stacking types of the heterostructure show dissimilarities, although\ntheir electronic structures are rather similar. This prediction can be used to\ndetermine the stacking type of ultra-thin heterostructures.",
        "positive": "Wurtzite phase control for self-assisted GaAs nanowires grown by\n  molecular beam epitaxy: The accurate control of the crystal phase in III-V semiconductor nanowires\n(NWs) is an important milestone for device applications. In this work, we\npresent a method to select and maintain the wurtzite (WZ) crystal phase in\nself-assisted NWs. By choosing a specific regime where the NW growth process is\na self-regulated system, the main experimental parameter to select the\nzinc-blende (ZB) or WZ phase is the V/III flux ratio. The latter can be\nmonitored by changing the As flux, and drives the system toward a stationary\nregime when the wetting angle of the Ga droplet falls in a target interval,\ntypically in the 90{\\deg} - 125{\\deg} range for the WZ phase growth. The\nanalysis of the in situ RHEED evolution, high-resolution scanning transmission\nelectron microscopy (HRSTEM), dark field transmission electron microscopy\n(DF-TEM), and photoluminescence (PL) data all confirm the control of an\nextended few micrometers long pure WZ segment obtained by MBE growth of\nself-assisted GaAs NWs with a V/III flux ratio of 4.0."
    },
    {
        "anchor": "Effects of Strain on Orbital Ordering and Magnetism at the Perovskite\n  Oxide Interfaces: LaMnO$_3$/SrMnO$_3$: We study how strain affects orbital ordering and magnetism at the interface\nbetween SrMnO$_3$ and LaMnO$_3$ from density-functional calculations and\ninterpret the basic results in terms of a three-site Mn-O-Mn model. Magnetic\ninteraction between the Mn atoms is governed by a competition between the\nantiferromagnetic superexchange of the Mn t$_{2g}$ core spins and the\nferromagnetic double exchange of the itinerant e$_g$ electrons. While the core\nelectrons are relatively unaffected by the strain, the orbital character of the\nitinerant electron is strongly affected, which in turn causes a large change in\nthe strength of the ferromagnetic double exchange. The epitaxial strain\nproduces the tetragonal distortion of the MnO$_6$ octahedron, splitting the\nMn-e$_g$ states into x$^2$-y$^2$ and 3z$^2$-1 states, with the former being\nlower in energy, if the strain is tensile in the plane, and opposite if the\nstrain is compressive. For the case of the tensile strain, the resulting higher\noccupancy of the x$^2$-y$^2$ orbital enhances the in-plane ferromagnetic double\nexchange owing to the larger electron hopping in the plane, causing at the same\ntime a reduction of the out-of-plane double exchange. This reduction is large\nenough to be overcome by antiferromagnetic superexchange, which wins to produce\na net antiferromagnetic interaction between the out-of-plane Mn atoms. For the\ncase of the in-plane compressive strain, the reverse happens, viz., that the\nhigher occupancy of the 3z$^2$-1 orbital results in the out-of-plane\nferromagnetic interaction, while the in-plane magnetic interaction remains\nantiferromagnetic. Concrete density-functional results are presented for the\n(LaMnO$_3$)$_1$/(SrMnO$_3$)$_1$ and (LaMnO$_3$)$_1$/(SrMnO$_3$)$_3$\nsuperlattices for various strain conditions.",
        "positive": "Suppression of the thermal hysteresis in magnetocaloric MnAs thin film\n  by highly charged ion bombardment: We present the investigation on the modifications of structural and magnetic\nproperties of MnAs thin film epitaxially grown on GaAs induced by slow highly\ncharged ions bombardment under well-controlled conditions. The ion-induced\ndefects facilitate the nucleation of one phase with respect to the other in the\nfirst-order magneto-structural MnAs transition with a consequent suppression of\nthermal hysteresis without any significant perturbation on the other structural\nand magnetic properties. In particular, the irradiated film keeps the giant\nmagnetocaloric effect at room temperature opening new perspective on magnetic\nrefrigeration technology for everyday use."
    },
    {
        "anchor": "Effect of changing the rare earth cation type on the structure and\n  crystallization behavior of an aluminoborosilicate glass: An aluminoborosilicate glass, containing high amount of rare earth (RE)\naccordingly to the following composition 50.68 SiO2 - 4.25 Al2O3 - 8.50 B2O3 -\n12.19 Na2O - 4.84 CaO - 3.19 ZrO2 - 16.35 RE2O3 (wt.%), is currently under\nstudy for the immobilization of nuclear waste solutions. In this work, we\nwanted to investigate the effect of changing the RE cation type on the glass\nstructure and on its crystallization behavior. For this purpose, a glass series\nwas elaborated in which the nature of the RE is varying from lanthanum to\nlutetium. In this glass series, only little effect was observed on the glass\nstructure. On the contrary, a strong impact was put in evidence on the\ncrystallization behavior through different heat treatments. A slow cooling of\nthe melt at 1^/circC/min, revealed significant crystallization of apatite\nCa2RE8(SiO4)6O2 in sample containing rare earths with ionic radii close to that\nof calcium. Another heat treatment consisting of successive nucleation and\ngrowth stages, performed to force the crystallization in the bulk and reduce\nany surface crystallization effect, put in evidence the existence of a strongly\nheterogeneous second rare earth rich silicate phase for samples containing RE\nwith low ionic radius (from Y to Lu).",
        "positive": "Reconstructing the exit wave in high-resolution transmission electron\n  microscopy using machine learning: Reconstruction of the exit wave function is an important route to\ninterpreting high-resolution transmission electron microscopy (HRTEM) images.\nHere we demonstrate that convolutional neural networks can be used to\nreconstruct the exit wave from a short focal series of HRTEM images, with a\nfidelity comparable to conventional exit wave reconstruction. We use a fully\nconvolutional neural network based on the U-Net architecture, and demonstrate\nthat we can train it on simulated exit waves and simulated HRTEM images of\ngraphene-supported molybdenum disulphide (an industrial desulfurization\ncatalyst). We then apply the trained network to analyse experimentally obtained\nimages from similar samples, and obtain exit waves that clearly show the\natomically resolved structure of both the MoS$_2$ nanoparticles and the\ngraphene support. We also show that it is possible to successfully train the\nneural networks to reconstruct exit waves for 3400 different two-dimensional\nmaterials taken from the Computational 2D Materials Database of known and\nproposed two-dimensional materials."
    },
    {
        "anchor": "Phonon structure of titanium under shear deformation along\n  $\\{10\\bar{1}2\\}$ twinning mode: We investigated phonon behavior of hexagonal close packed titanium under\nhomogeneous shear deformation corresponding to the $\\{10\\bar{1}2\\}$ twinning\nmode using first-principles calculation and phonon calculation. By this\ndeformation, we found that a phonon mode located at a point on Brillouin zone\nboundary is drastically soften increasing the shear and finally it triggers a\nspontaneous structural transition by breaking the crystal symmetry toward twin\nfrom parent.",
        "positive": "NMR measurements of hyperpolarized 3He gas diffusion in high porosity\n  silica aerogels: Hyperpolarized 3He is used to nondestructively probe by NMR the structure of\ncustom-made and commercial silica aerogels (97% and 98.5% porous). Large\nspin-echo signals are obtained at room temperature and very low magnetic field\n(2mT) even with small mounts of gas. Attenuation induced by applied field\ngradients results from the combined effects of gas diffusion and confinement by\nthe porous medium on atomic motion. Nitrogen is used as a buffer gas to reach\nequivalent 3He pressures ranging from 5 mbars to 3.5 bars. The observed\npressure dependence suggests a non-uniform structure of the aerogels on length\nscales up to tens of micrometers. A description by broad phenomenological\ndistributions of mean free paths is proposed, and quantitatively discussed by\ncomparison to numerical calculations. The investigated aerogel samples exhibit\ndifferent effective diffusion characteristics despite comparable nominal\nporosities."
    },
    {
        "anchor": "Raman and photoluminescence spectroscopic studies on structural disorder\n  in oxygen deficient Gd2Ti2O7-d single crystals: We report on Raman and photoluminescence spectroscopic studies on oxygen\nvacancy induced structural disorder in Gd2Ti2O7-d single crystals grown by\noptical floating zone technique under argon atmosphere. The oxygen vacancies in\nGd2Ti2O7-d wafers decrease with thermal annealing in an air atmosphere. The\nfull width at half maximum of X-ray diffraction rocking curve decreases from\n245 to 157 arc-second and the optical transmittance increases from 23 to 87 %\n(at 1000 nm) upon post growth thermal annealing. Raman spectroscopic studies\nreveal a monotonic increase in intensity of O-Gd-O (Eg) and Ti-O (A1g)\nstretching modes with thermal annealing. Since these modes are associated with\nmodulation of oxygen x parameter which is sensitive to Ti-O octahedron\ndistortion, the increase in Raman intensity indicates an improvement in\nstructural ordering of oxygen sub-lattice in Gd2Ti2O7-d. Moreover, the\nphotoluminescence studies also corroborate the Raman analysis in terms of\nreduction of structural defects associated with oxygen vacancies as a function\nof thermal annealing. This study demonstrates the effectiveness of using Raman\nspectroscopy to probe the structural disorder in Gd2Ti2O7-d crystals.",
        "positive": "Graphene with the secondary amine-terminated zigzag edge as a line\n  electron emitter: An extraordinary low vacuum barrier height of 2.30 eV has been found on the\nzigzag-edge of graphene terminated with the secondary amine via the ab initio\ncalculation. This edge structure has a flat band of edge states attached to the\ngamma point where the transversal kinetic energy is vanishing. We show that the\nfield electron emission is dominated by the flat band. The edge states pin the\nFermi level to a constant, leading to an extremely narrow emission energy\nwidth. The graphene with such edge is a promising line field electron emitter\nthat can produce highly coherent emission current."
    },
    {
        "anchor": "Antiferroelectricity in thin film ZrO2 from first principles: Density functional calculations are performed to investigate the\nexperimentally-reported field-induced phase transition in thin-film ZrO2 (J.\nMuller et al., Nano. Lett. 12, 4318). We find a small energy difference of ~ 1\nmeV/f.u. between the nonpolar tetragonal and polar orthorhombic structures,\ncharacteristic of antiferroelectricity. The requisite first-order transition\nbetween the two phases, which atypically for antiferroelectrics have a\ngroup-subgroup relation, results from coupling to other zone-boundary modes, as\nwe show with a Landau-Devonshire model. Tetragonal ZrO2 is thus established as\na previously unrecognized lead-free antiferroelectric with excellent dielectric\nproperties and compatibility with silicon. In addition, we demonstrate that a\nferroelectric phase of ZrO2 can be stabilized through epitaxial strain, and\nsuggest an alternative stabilization mechanism through continuous substitution\nof Zr by Hf.",
        "positive": "Defect-induced helicity-dependent terahertz emission in Dirac semimetal\n  PtTe2 thin films: Nonlinear transport enabled by symmetry breaking in quantum materials has\naroused considerable interest in condensed matter physics and interdisciplinary\nelectronics. However, the nonlinear optical response in centrosymmetric Dirac\nsemimetals via the defect engineering has remained highly challenging. Here, we\nobserve the helicity-dependent terahertz (THz) emission in Dirac semimetal\nPtTe2 thin films via circular photogalvanic effect (CPGE) under normal\nincidence. This is activated by artificially controllable out-of-plane\nTe-vacancy defect gradient, which is unambiguously evidenced by the electron\nptychography. The defect gradient lowers the symmetry, which not only induces\nthe band spin splitting, but also generates the giant Berry curvature dipole\n(BCD) responsible for the CPGE. Such BCD-induced helicity-dependent THz\nemission can be manipulated by the Te-vacancy defect concentration.\nFurthermore, temperature evolution of the THz emission features the minimum of\nthe THz amplitude due to the carrier compensation. Our work provides a\nuniversal strategy for symmetry breaking in centrosymmetric Dirac materials for\nefficient nonlinear transport and facilitates the promising device applications\nin integrated optoelectronics and spintronics."
    },
    {
        "anchor": "Boron phosphide films by reactive sputtering: Searching for a p-type\n  transparent conductor: With an indirect band gap in the visible and a direct band gap at a much\nhigher energy, boron phosphide (BP) holds promise as an unconventional p-type\ntransparent conductor. Previous experimental reports deal almost exclusively\nwith epitaxial, nominally undoped BP films by chemical vapor deposition. High\nhole concentrations were often observed, but it is unclear if native defects\nalone can be responsible for it. Besides, the feasibility of alternative\ndeposition techniques has not been clarified and optical characterization is\ngenerally lacking. In this work, we demonstrate reactive sputtering of\namorphous BP films, their partial crystallization in a P-containing annealing\natmosphere, and extrinsic doping by C and Si. We obtain the highest hole\nconcentration reported to date for p-type BP ($5 \\times 10^{20}$ cm$^{-3}$)\nusing C doping under B-rich conditions. We also confirm that bipolar doping is\npossible in BP. An anneal temperature of at least 1000 $^\\circ$C is necessary\nfor crystallization and dopant activation. Hole mobilities are low and indirect\noptical transitions are much stronger than predicted by theory. Low crystalline\nquality probably plays a role in both cases. High figures of merit for\ntransparent conductors might be achievable in extrinsically doped BP films with\nimproved crystalline quality.",
        "positive": "Fitting Laguerre tessellation approximations to tomographic image data: The analysis of polycrystalline materials benefits greatly from accurate\nquantitative descriptions of their grain structures. Laguerre tessellations\napproximate such grain structures very well. However, it is a quite challenging\nproblem to fit a Laguerre tessellation to tomographic data, as a\nhigh-dimensional optimization problem with many local minima must be solved. In\nthis paper, we formulate a version of this optimization problem that can be\nsolved quickly using the cross-entropy method, a robust stochastic optimization\ntechnique that can avoid becoming trapped in local minima. We demonstrate the\neffectiveness of our approach by applying it to both artificially generated and\nexperimentally produced tomographic data."
    },
    {
        "anchor": "Quantum body in uniform electric fields: The advent in this century of nano and microelectronics requires, by part of\nphysicists and engineers, the need of an explanation of electrical phenomena\nsuch as the interaction of a body with external electric fields at its atomic\nlevel,i.e. where is the case of the appearance of the quantum nature of\nphenomena involved in the projecting of nano an micro devices. It is mainly\nfocused in this article the problem of calculating eigenstates of quantum\nmatter interacting with a uniform external electric field, whose solution is\nreported via a DFT(Density Functional Theory) variational approach[3,4].",
        "positive": "Micromagnetic simulations of absoption spectra: Further development of a previously introduced method for numerically\nsimulating magnetic spin waves is presented. Together with significant\nimprovements in speed, the method now allows one to calculate the energy\nabsorbed by the various modes excited by a position- and time-dependent H1\nfield in a ferromagnetic body of arbitrary shape in the presence of a (uniform\nor non uniform) static H0 field as well as the internal exchange and anisotropy\nfields. The method is applied to the case of the single vortex state in a thin\ndisc, a ring, and various square slabs, for which the absorption spectra are\ncalculated and the most strongly excited resonance modes are identified."
    },
    {
        "anchor": "Surface parameters of ferritic iron-rich Fe-Cr alloy: Using first-principles density functional theory in the implementation of the\nexact muffin-tin orbitals method and the coherent potential approximation, we\nstudied the surface energy and the surface stress of the thermodynamically most\nstable surface facet (100) of the homogeneous disordered body-centred cubic\niron-chromium system in the concentration interval up to 20 at.% Cr. For the\nlow-index surface facets of Fe and Cr, the surface energy of Cr is slightly\nlarger than the one of Fe, while the surface stress of Cr is considerably\nsmaller than the one of Fe. We find that Cr addition to Fe generally increases\nthe surface energy of the Fe-Cr alloy, however, an increase of the bulk amount\nof Cr also increases the surface stress. As a result of this unexpected trend,\nthe (100) surface of Fe-Cr becomes more stable against reconstruction with\nincreasing Cr concentration. We show that the observed trends are of magnetic\norigin. In addition to the homogeneous alloy case, we also investigated the\nimpact of surface segregation on both surface parameters.",
        "positive": "Chemical control of the charge state of nitrogen-vacancy centers in\n  diamond: We investigate the effect of surface termination on the charge state of\nnitrogen vacancy centers, which have been ion-implanted few nanometers below\nthe surface of diamond. We find that, when changing the surface termination\nfrom oxygen to hydrogen, previously stable NV- centers convert into NV0 and,\nsubsequently, into an unknown non-fluorescent state. This effect is found to\ndepend strongly on the implantation dose. Simulations of the electronic band\nstructure confirm the dissappearance of NV- in the vicinity of the\nhydrogen-terminated surface. The band bending, which induces a p-type surface\nconductive layer leads to a depletion of electrons in the nitrogen vacancies\nclose to the surface. Therefore, hydrogen surface termination provides a\nchemical way for the control of the charge state of nitrogen-vacancy centers in\ndiamond. Furthermore, it opens the way to an electrostatic control of the\ncharge state with the use of an external gate electrode."
    },
    {
        "anchor": "Status and direction of atom probe analysis of frozen liquids: Imaging of liquids and cryogenic biological materials by electron microscopy\nhas been recently enabled by innovative approaches for specimen preparation and\nthe fast development of optimised instruments for cryo-enabled electron\nmicroscopy (cryo-EM). Yet, Cryo-EM typically lacks advanced analytical\ncapabilities, in particular for light elements. With the development of\nprotocols for frozen wet specimen preparation, atom probe tomography (APT)\ncould advantageously complement insights gained by cryo-EM. Here, we report on\ndifferent approaches that have been recently proposed to enable the analysis of\nrelatively large volumes of frozen liquids from either a flat substrate or the\nfractured surface of a wire. Both allowed for analysing water ice layers which\nare several microns thick consisting of pure water, pure heavy-water and\naqueous solutions. We discuss the merits of both approaches, and prospects for\nfurther developments in this area. Preliminary results raise numerous\nquestions, in part concerning the physics underpinning field evaporation. We\ndiscuss these aspects and lay out some of the challenges regarding the APT\nanalysis of frozen liquids.",
        "positive": "Unprecedentedly Wide Curie-Temperature Windows as Phase-Transition\n  Design Platform for Tunable Magneto-Multifunctional Materials: A series of unprecedentedly wide Curie-temperature windows (CTWs) between 40\nand 450 K are realized by employing the isostructural alloying principle for\nthe strongly coupled magnetostructural phase transitions in a single host\nsystem. The CTWs provide a design platform for magneto-multifunctional\nmultiferroic alloys that can be manipulated in a quite large temperature space\nin various scales and patterns, as well as by multiple physical fields."
    },
    {
        "anchor": "Spin mapping of intralayer antiferromagnetism and spin-flop transition\n  in monolayer CrTe$_2$: Intrinsic antiferromagnetism in van der Waals (vdW) monolayer (ML) crystals\nenriches the understanding regarding two-dimensional (2D) magnetic orders and\nholds special virtues over ferromagnetism in spintronic applications. However,\nthe studies on intrinsic antiferromagnetism are sparse, owing to the lack of\nnet magnetisation. In this study, by combining spin-polarised scanning\ntunnelling microscopy and first-principles calculations, we investigate the\nmagnetism of vdW ML CrTe2, which has been successfully grown through molecular\nbeam epitaxy. Surprisingly, we observe a stable antiferromagnetic (AFM) order\nat the atomic scale in the ML crystal, whose bulk is a strong ferromagnet, and\ncorrelate its imaged zigzag spin texture with the atomic lattice structure. The\nAFM order exhibits an intriguing noncollinear spin-flop transition under\nmagnetic fields, consistent with its calculated moderate magnetic anisotropy.\nThe findings of this study demonstrate the intricacy of 2D vdW magnetic\nmaterials and pave the way for their in-depth studies.",
        "positive": "Electron and Hole Injection via Charge Transfer at the\n  Topological-Insulator $Bi_{2-x}Sb_xTe_{3-y}Se_y$/Organic-Molecule Interface: As a methodology for controlling the carrier transport of topological\ninsulators (TI's), a flexible tuning in carrier number on the surface states\n(SS's) of three dimensional TI's by surface modifications using organic\nmolecules is described. The principle of the carrier tuning and its type\nconversion of TI's presented in this research are based on the charge transfer\nof holes or electrons at the TI/organic molecule interface. By employing\n2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) as an electron\nacceptor or tetracyanoquinodimethane (TCNQ) as a donor for n- and p-\nBi2-xSbxTe3-ySey (BSTS) single crystals, successful carrier conversion from n\nto p and its reverse mode is demonstrated depending on the electron affinities\nof the molecules. The present method provides a nondestructive and efficient\nmethod for local tuning in carrier density of TI's, and is useful for future\napplications."
    },
    {
        "anchor": "Observation of Shubnikov-de Haas Oscillations in Large-Scale Weyl\n  Semimetal WTe2 Films: Topological Weyl semimetal WTe2 with large-scale film form has a promising\nprospect for new-generation spintronic devices. However, it remains a hard task\nto suppress the defect states in large-scale WTe2 films due to the chemical\nnature. Here, we significantly improve the crystalline quality and remove the\nTe vacancies in WTe2 films by post annealing. We observe the distinct\nShubnikov-de Haas quantum oscillations in WTe2 films. The nontrivial Berry\nphase can be revealed by Landau fan diagram analysis. The Hall mobility of WTe2\nfilms can reach 1245 cm2V-1s-1 and 1423 cm2V-1s-1 for holes and electrons with\nthe carrier density of 5 * 10^19 cm^-3 and 2 * 10^19 cm^-3, respectively. Our\nwork provides a feasible route to obtain high-quality Weyl semimetal films for\nthe future topological quantum device applications.",
        "positive": "Graph theory-based structural analysis on density anomaly of silica\n  glass: Analyzing the atomic structure of glassy materials is a tremendous challenge\nboth experimentally and computationally, and the lack of direct, detailed\ninsights into glass structure hinders our ability to navigate\nstructure-property relationships. For instance, the structural origin of the\ndensity anomaly in silica glasses - the negative thermal expansion coefficient\n- is still poorly understood. Simulations based on molecular dynamics (MD)\nproduce atomically resolved structures, but quantifying the role of disorder in\nthe density anomaly is challenging. Here, we propose to use a a\ngraph-theoretical approach to assess topological differences between disordered\nstructural arrangements from MD trajectories of silica glasses. A graph\nsimilarity metric quantifies the similarity between the covalent networks and\ncan characterize the nature of the disordered solid, by comparing to reference\ncrystalline solids, or with glasses in different thermodynamic states . This\napproach involves casting all-atom glass configurations as networks, and\nsubsequently applying a graph-similarity metric (D-measure). Calculated\nD-measure values are then taken as the topological distances between two\nconfigurations. By measuring the topological distances of silica glass\nconfigurations across a range of temperatures, distinct structural features\ncould be observed at temperatures higher than the fictive temperature. In\naddition, we compared topological distances between local atomic environments\nin the glass and crystalline silica phases. This approach suggests that more\ncoesite-like and quartz-like local structures emerge in silica glasses when the\ndensity is at a minimum during the heating process."
    },
    {
        "anchor": "Multifunctional Antiferromagnetic Materials with Giant Piezomagnetism\n  and Noncollinear Spin Current: We propose a new type of spin-valley locking (SVL), named $\\textit{C}$-paired\nSVL, in antiferromagnetic systems, which directly connects the spin/valley\nspace with the real space, and hence enables both static and dynamical controls\nof spin and valley to realize a multifunctional antiferromagnetic material. The\nnew emergent quantum degree of freedom in the $\\textit{C}$-paired SVL is\ncomprised of spin-polarized valleys related by a crystal symmetry instead of\nthe time-reversal symmetry. Thus, both spin and valley can be accessed by\nsimply breaking the corresponding crystal symmetry. Typically, one can use a\nstrain field to induce a large net valley polarization/magnetization and use a\ncharge current to generate a large noncollinear spin current. We predict the\nrealization of the $\\textit{C}$-paired SVL in monolayer V$_2$Se$_2$O, which\nindeed exhibits giant piezomagnetism and can generate a large transverse spin\ncurrent. Our findings provide unprecedented opportunities to integrate various\ncontrols of spin and valley with nonvolatile information storage in a single\nmaterial, which is highly desirable for versatile fundamental research and\ndevice applications.",
        "positive": "Ab initio derivation of multi-orbital extended Hubbard model for\n  molecular crystals: From configuration interaction (CI) ab initio calculations, we derive an\neffective two-orbital extended Hubbard model based on the gerade (g) and\nungerade (u) molecular orbitals (MOs) of the charge-transfer molecular\nconductor (TTM-TTP)I_3 and the single-component molecular conductor\n[Au(tmdt)_2]. First, by focusing on the isolated molecule, we determine the\nparameters for the model Hamiltonian so as to reproduce the CI Hamiltonian\nmatrix. Next, we extend the analysis to two neighboring molecule pairs in the\ncrystal and we perform similar calculations to evaluate the inter-molecular\ninteractions. From the resulting tight-binding parameters, we analyze the band\nstructure to confirm that two bands overlap and mix in together, supporting the\nmulti-band feature. Furthermore, using a fragment decomposition, we derive the\neffective model based on the fragment MOs and show that the staking TTM-TTP\nmolecules can be described by the zig-zag two-leg ladder with the\ninter-molecular transfer integral being larger than the intra-fragment transfer\nintegral within the molecule. The inter-site interactions between the fragments\nfollow a Coulomb law, supporting the fragment decomposition strategy."
    },
    {
        "anchor": "Low temperature ferromagnetic properties, magnetic field induced spin\n  order and random spin freezing effect in Ni1.5Fe1.5O4 ferrite; prepared at\n  different pH values and annealing temperatures: We present the low temperature magnetic properties in Ni1.5Fe1.5O4 ferrite as\nthe function of pH at which the material was prepared by chemical route and\npost annealing temperature. The material is a ferri or ferromagnet, but showed\nmagnetic blocking and random spin freezing process on lowering the measurement\ntemperature down to 5 K. The sample prepared at pH =12 and annealed at 800 ^C\nshowed a sharp magnetization peak at 105 K, the superparamagnetic blocking\ntemperature of the particles. The magnetization peak remained incomplete within\nmeasurement temperature up to 350 K for rest of the samples, although peak\ntemperature was brought down by increasing applied dc field. The fitting of\ntemperature dependence of coercivity data according to Kneller law suggested\nrandom orientation of ferromagnetic particles. The fitting of saturation\nmagnetization according to Bloch law provided the exponent that largely\ndeviated from 1.5, a typical value for long ranged ferromagnet. An abrupt\nincrease of saturation magnetization below 50 K suggested the active role of\nfrozen surface spins in low temperature magnetic properties. AC susceptibility\ndata elucidated the low temperature spin freezing dynamics and exhibited the\ncharacters of cluster spin glass in the samples depending on pH value and\nannealing temperature.",
        "positive": "Spin dependent charge transfer in MoSe2/hBN/Ni hybrid structures: We present magneto-photoluminescence measurements in a hybrid 2D\nsemiconductor/ferromagnetic structure consisting of MoSe2/hBN/Ni. When the\nNickel layer is magnetized, we observe circularly polarized photoluminescence\nof the trion peak in MoSe2 monolayer under linearly polarized excitation. This\nbuild-up of circular polarization can reach a measured value of about 4% when\nthe magnetization of Ni is saturated perpendicularly to the sample plane, and\nchanges its sign when the magnetization is reversed. The circular polarization\ndecreases when the hBN barrier thickness increases. These results are\ninterpreted in terms of a spin-dependent charge transfer between the MoSe2\nmonolayer and the Nickel film. The build-up of circular polarization is\nobserved up to 120 K, mainly limited by the trion emission that vanishes with\ntemperature."
    },
    {
        "anchor": "Reaction energetics and crystal structure of Li4BN3H10 from first\n  principles: Using density functional theory we examine the crystal structure and the\nfinite-temperature thermodynamics of formation and dehydrogenation for the new\nquaternary hydride Li4BN3H10. Two recent studies based on X-ray and neutron\ndiffraction have reported three bcc crystal structures for this phase. While\nthese structures possess identical space groups and similar lattice constants,\ninternal coordinate differences result in bond length discrepancies as large as\n0.2 A. Geometry optimization calculations on the experimental structures reveal\nthat the apparent discrepancies are an artifact of X-ray interactions with\nstrong bond polarization; the relaxed structures are essentially identical.\nRegarding reaction energetics, the present calculations predict that the\nformation reaction 3LiNH2 + LiBH4 -> Li4BN3H10 is exothermic with enthalpy\nDelta H(T=300K) = -11.8 kJ/(mol f.u.), consistent with reports of spontaneous\nLi4BN3H10 formation in the literature. Calorimetry experiments have been\nreported for the dehydrogenation reaction, but have proven difficult to\ninterpret. To help clarify the thermodynamics we evaluate the free energies of\nseventeen candidate dehydrogenation pathways over the temperature range T =\n0-1000 K. At temperatures where H2 release has been experimentally observed (T\n\\~ 520-630 K), the favored dehydrogenation reaction is Li4BN3H10 -> Li3BN2 +\nLiNH2 + 4 H2, which is weakly endothermic [Delta H(T=550K) = 12.8 kJ/(mol H2)].\nThe small calculated Delta H is consistent with the unsuccessful attempts at\nre-hydriding reported in the literature, and suggests that the moderately high\ntemperatures needed for H-desorption result from slow kinetics.",
        "positive": "Magnetic proximity effect on excitonic spin states in Mn-doped layered\n  hybrid perovskites: Materials combining the optoelectronic functionalities of semiconductors with\ncontrol of the spin degree of freedom are highly sought after for the\nadvancement of quantum technology devices. Here, we report the paramagnetic\nRuddlesden-Popper hybrid perovskite Mn:(PEA)2PbI4 (PEA = phenethylammonium) in\nwhich the interaction of isolated Mn2+ ions with magnetically brightened\nexcitons leads to circularly polarized photoluminescence. Using a combination\nof superconducting quantum interference device (SQUID) magnetometry and\nmagneto-optical experiments, we find that the Brillouin-shaped polarization\ncurve of the photoluminescence follows the magnetization of the material. This\nindicates coupling between localized manganese magnetic moments and exciton\nspins via a magnetic proximity effect. The saturation polarization of 15% at 4\nK and 6 T indicates a highly imbalanced spin population and demonstrates that\nmanganese doping enables efficient control of excitonic spin states in\nRuddlesden-Popper perovskites. Our finding constitutes the first example of\npolarization control in magnetically doped hybrid perovskites and will\nstimulate research on this highly tuneable material platform that promises\ntailored interactions between magnetic moments and electronic states."
    },
    {
        "anchor": "Aging Dynamics in Ferroelectric Deuterated Potassium Dihydrogen\n  Phosphate: Anomalously large dielectric aging is found in the high-susceptibility\nplateau ferroelectric regime of ~95% deuterated potassium dihydrogen phosphate\n(DKDP). Much less aging is found in non-deuterated KDP. Optical images of the\nDKDP domain structure show no dramatic change during aging. Small changes in\nelectric field restore the pre-aged susceptibility, but the previous aging\nalmost recovers after returning to the aging field. Susceptibility vs. field\ncan show memory of at least two prior aging fields. Rectifying non-linear\nsusceptibility develops for fields slightly above or below a prior aging field.\nAging effects are not fully erased even by brief heating above the Curie point,\nindicating a role for diffusion of hydrogen to the domain walls, leaving\nchanges in disorder that can survive temporary absence of domain walls. Abrupt\nrandom-sign steps in polarization on cooling are accompanied by increases in\nsusceptibility, indicating competition between large-scale domain-wall\ninteraction effects and effects of local interactions with disorder.",
        "positive": "Superplasticity-like behavior of ultrafine-grained austenitic steel 321: Hot rolled commercial metastable austenitic steel 321 with strongly elongated\nthin delta-ferrite particles in its microstructure was the object of\ninvestigations. Ultrafine-grained (UFG) microstructure in steel 321 was formed\nby Equal Channel Angular Pressing (ECAP) at 150 oC and 450 oC. When heating the\nUFG steel specimens, the nucleation of sigma-phase particles blocking the grain\nboundary migration was observed. The maximum elongation to failure (~250%) was\nachieved at the deformation temperature 750 oC. The process of superplastic\ndeformation of the UFG steel 321 is controlled by simultaneous grain boundary\nsliding and power-law creep. The contribution of each process depends on the\ngrain growth rate in the superplasticity regime as well as on defect\naccumulation on the grain boundaries. The fracture of the UFG steel 321\nspecimens has a cavitational character - an intensive formation of large\nelongated pores at the non-metallic particles as well as of the submicron pores\nat the sigma-phase particles in the course of superplastic deformation were\nobserved."
    },
    {
        "anchor": "Fourier-based methods for removing mesh anomalies from angle resolved\n  photoemission spectra: Recent improvements to spatial resolution in angle-resolved photo-emission\nspectroscopy (ARPES) have made it common to perform measurements with a very\nbrief dwell time, for the purpose of mapping the spectral function over large\nsurface regions. However, rapid measurement modalities can suffer a grid-like\nintensity modulation due to a wire mesh that is typically placed in front of\nthe ARPES detector to block stray electrons. Here, we explore Fourier-based\nmethods that can effectively remove this artifact, and improve the quality of\nARPES images obtained in rapid scanning modes. An open source software package\nis provided containing implementations of demonstrated algorithms.",
        "positive": "Dynamics of Magnetization Reversal in Models of Magnetic Nanoparticles\n  and Ultrathin Films: We discuss numerical and theoretical results for models of magnetization\nswitching in nanoparticles and ultrathin films. The models and computational\nmethods include kinetic Ising and classical Heisenberg models of highly\nanisotropic magnets which are simulated by dynamic Monte Carlo methods, and\nmicromagnetics models of continuum-spin systems that are studied by\nfinite-temperature Langevin simulations. The theoretical analysis builds on the\nfact that a magnetic particle or film that is magnetized in a direction\nantiparallel to the applied field is in a metastable state. Nucleation theory\nis therefore used to analyze magnetization reversal as the decay of this\nmetastable phase to equilibrium. We present numerical results on magnetization\nreversal in models of nanoparticles and films, and on hysteresis in magnets\ndriven by oscillating external fields."
    },
    {
        "anchor": "In-plane and out-of-plane optical response of the nodal-line semimetals\n  ZrGeS and ZrGeSe: Polarization-dependent reflectivity measurements were carried out over a\nbroad frequency range on single-crystalline ZrGeSe and ZrGeS compounds, which\nare closely related to the prototype nodal-line semimetal ZrSiS. These\nmeasurements revealed the strongly anisotropic character of both ZrGeSe and\nZrGeS, with a reduced plasma frequency for the out-of-plane direction {\\bf\nE}$\\| c$ as compared to the in-plane direction {\\bf E}$\\| ab$. For {\\bf E}$\\|\nab$ the optical conductivity spectrum consists of two Drude terms followed by a\nshoulder or plateau-like behavior and a distinct U shape at higher energies,\nwhile for {\\bf E}$\\| c$ one Drude term is followed by a peak-like behavior and\nthe U shape of the profile is less developed. Under external pressure, two\nprominent excitations appear in the out-of-plane optical conductivity spectrum\nof ZrGeSe, whose frequency position and oscillator strength show a weak anomaly\nat $\\sim$3~GPa. Overall, the pressure-induced changes in the profile of the\n{\\bf E}$\\| c$ conductivity spectrum are much enhanced above $\\sim$3~GPa. We\ncompare our results to those recently reported for ZrSiS in a quantitative\nmanner.",
        "positive": "Electrochemical Screening of Contact Layers for Metal Halide Perovskites: Optimizing selective contact layers in photovoltaics is necessary to yield\nhigh performing stable devices. However, this has been difficult for\nperovskites due to their complex interfacial defects that affect carrier\nconcentrations in the active layer as well as charge transfer and recombination\nat the interface. Using vacuum thermally-evaporated tin oxide as a case study,\nwe highlight electrochemical tests that are simple yet screen device-relevant\ncontact layer properties, making them useful for process development and\nquality control. Specifically, we show that cyclic voltammetry and\npotentiostatic chronoamperometry correlate to key performance parameters in\ncompleted devices as well as other material/interfacial properties relevant to\ndevices such as shunt pathways and chemical composition. Having fast, reliable,\nscalable, and actionable probes of electronic properties is increasingly\nimportant as halide perovskite photovoltaics approach their theoretical limits\nand scale to large-area devices."
    },
    {
        "anchor": "Superior lattice thermal conductance of single layer borophene: By way of the nonequilibrium Green's function simulations and first\nprinciples calculations, we report that borophene, a single layer of boron\natoms that was fabricated recently, possesses an extraordinarily high lattice\nthermal conductance in the ballistic transport regime, which even exceeds\ngraphene. In addition to the obvious reasons of light mass and strong bonding\nof boron atoms, the superior thermal conductance is mainly rooted in its strong\nstructural anisotropy and unusual phonon transmission. For low-frequency\nphonons, the phonon transmission within borophene is nearly isotropic, similar\nto that of graphene. For high frequency phonons, however, the transmission is\none dimensional, that is, all the phonons travel in one direction, giving rise\nto its ultrahigh thermal conductance. The present study suggests that borophene\nis promising for applications in efficient heat dissipation and thermal\nmanagement, and also an ideal material for revealing fundamentals of\ndimensionality effect on phonon transport in ballistic regime.",
        "positive": "Ferromagnetism and magneto-dielectric effect in insulating\n  LaBiMn4/3Co2/3O6 thin films: High quality epitaxial thin films of LaBiMn4/3Co2/3O6 perovskite were\nfabricated on (001)-oriented SrTiO3 and LaAlO3 substrates by the pulsed laser\ndeposition technique. Magnetization measurements reveal a strong magnetic\nanisotropy and a ferromagnetic behavior that is in agreement with a\nsuper-exchange interaction between Mn4+ and Co2+ ions, which are randomly\ndistributed in the B-site. A distinct anomaly is observed in the dielectric\nmeasurements at 130K corresponding to the onset of the magnetic ordering,\nsuggesting a coupling. Above this temperature, the extrinsic Maxwell-Wagner\neffect is dominating. Theses results are explained using the Raman\nspectroscopic studies indicating a weak spin-lattice interaction around this\nmagnetic transition."
    },
    {
        "anchor": "Reversible Thermal Strain Control of Oxygen Vacancy Ordering in an\n  Epitaxial La$_{0.5}$Sr$_{0.5}$CoO$_{3-\u03b4}$ Film: Reversible topotactic transitions between oxygen-vacancy-ordered structures\nin transition metal oxides provide a promising strategy for active manipulation\nof material properties. While transformations between various oxygen-deficient\nphases have been attained in bulk ABO$_{3-\\delta}$ perovskites, substrate\nclamping restricts the formation of distinct ordering patterns in epitaxial\nfilms. Using in-situ scanning transmission electron microscopy (STEM), we image\na thermally driven reversible transition in\nLa$_{0.5}$Sr$_{0.5}$CoO$_{3-\\delta}$ films on SrTiO$_3$ from a multidomain\nbrownmillerite (BM) structure to a uniform phase wherein oxygen vacancies order\nin every third CoO$_x$ plane. Because temperature cycling is performed over a\nlimited temperature range (25 {\\deg}C - 385 {\\deg}C), the oxygen deficiency\nparameter $\\delta$ does not vary measurably. Under constant $\\delta$, the\ntopotactic transition proceeds via local reordering of oxygen vacancies driven\nby thermal strain. Atomic-resolution imaging reveals a two-step process whereby\nalternating vertically and horizontally oriented BM domains first scale in size\nto accommodate the strain induced by different thermal expansions of\nLa$_{0.5}$Sr$_{0.5}$CoO$_{3-\\delta}$ and SrTiO$_3$, before the new phase\nnucleates and quickly grows above 360 {\\deg}C. Upon cooling, the film transform\nback to the mixed BM phase. As the structural transition is fully reversible\nand $\\delta$ does not change upon temperature cycling, we rule out\nelectron-beam irradiation during STEM as the driving mechanism. Instead, our\nfindings demonstrate that thermal strain can solely drive topotactic phase\ntransitions in perovskite oxide films, presenting opportunities for switchable\nionic devices.",
        "positive": "Insights into image contrast from dislocations in ADF-STEM: Competitive mechanisms contribute to image contrast from dislocations in\nannular dark field scanning transmission electron microscopy ADF STEM. A clear\ntheoretical understanding of the mechanisms underlying the ADF STEM contrast is\ntherefore essential for correct interpretation of dislocation images. This\npaper reports on a systematic study of the ADF STEM contrast from dislocations\nin a GaN specimen, both experimentally and computationally. Systematic\nexperimental ADF STEM images of the edge character dislocations revealed a\nnumber of characteristic contrast features that are shown to depend on both the\nangular detection range and specific position of the dislocation in the sample.\nA theoretical model based on electron channelling and Bloch wave scattering\ntheories, supported by multislice simulations using Grillo s strain channelling\nequation, is proposed to elucidate the physical origin of such complex contrast\nphenomena."
    },
    {
        "anchor": "Ab initio study of the thermodynamic properties of rare-earthmagnesium\n  intermetallics MgRE (RE=Y, Dy, Pr, Tb): We have performed an ab initio study of the thermodynamical properties of\nrare-earth-magnesium intermetallic compounds MgRE (RE=Y, Dy, Pr, Tb) with\nCsCl-type B2-type structures. The calculations have been carried out the\ndensity functional theory and density functional perturbation theory in\ncombination with the quasiharmonic approximation. The phonon-dispersion curves\nand phonon total and partial density of states have been investigated. Our\nresults show that the contribution of RE atoms is dominant in phonon frequency,\nand this character agrees with the previous discussion by using atomistic\nsimulations. The temperature dependence of various quantities such as the\nthermal expansions, bulk modulus, and the heat capacity are obtained. The\nelectronic contributions to the specific heat are discussed, and found to be\nimportant for the calculated MgRE intermetallics.",
        "positive": "Multiscale mechanical study of the Turritella terebra and\n  Turritellinella tricarinata seashells: Marine shells are designed by nature to ensure mechanical protection from\npredators and shelter for mollusks living inside them. A large amount of work\nhas been done to study the multiscale mechanical properties of their complex\nmicrostructure and to draw inspiration for the design of impact-resistant\nbiomimetic materials. Less is known regarding the dynamic behavior related to\ntheir structure at multiple scales. Here, we present a combined experimental\nand numerical study of the shells of two different species of gastropod sea\nsnail belonging to the Turritellidae family, featuring a peculiar helicoconic\nshape with hierarchical spiral elements. The proposed procedure involves the\nuse of micro-Computed Tomography scans for the accurate determination of\ngeometry, Atomic Force Microscopy and Nanoindentation to evaluate local\nmechanical properties, surface morphology and heterogeneity, as well as\nResonant Ultrasound Spectroscopy coupled with Finite Element Analysis\nsimulations to determine global modal behavior. Results indicate that the\nspecific features of the considered shells, in particular their helicoconic and\nhierarchical structure, can also be linked to their vibration attenuation\nbehavior. Moreover, the proposed investigation method can be extended to the\nstudy of other natural systems, to determine their structure-related dynamic\nproperties, ultimately aiding the design of bioinspired metamaterials and of\nstructures with advanced vibration control."
    },
    {
        "anchor": "Growth and Investigation of Nd_{1-x}Sm_{x}ScO_{3} and\n  Sm_{1-x}Gd_{x}ScO_{3} Solid-Solution Single Crystals: The pseudo-cubic lattice parameters of rare-earth (RE) scandate, REScO3,\nsingle crystals grown by the Czochralski technique with RE=Dy to Pr lie between\nabout 3.95 and 4.02 Angstrom. These crystals are the only available perovskite\nsubstrates in this lattice constant range that can withstand virtually any thin\nfilm growth conditions. Two members of this series, PmScO3 and EuScO3, are,\nhowever, not suitable for substrate applications. Because the pseudo-cubic\nlattice parameters between neighbouring REScO3 compounds decrease with rising\natomic number of the RE in about 0.01 Angstrom steps, the unsuitability of\nPmScO3 (radioactivity) and EuScO3 (incompatibility with Si) causes an\ninterruption in this lattice spacing sequence. To replace them, solid solutions\nof their adjacent rare-earth scandates, i.e., (Nd0.5Sm0.5)ScO3 and\n(Sm0.5Gd0.5)ScO3, were grown by the Czochralski method. Their average\npseudo-cubic lattice parameters of 3.9979 Angstrom and 3.9784 Angstrom are very\nclose to those of PmScO3 and EuScO3, respectively, and they show very low\nsegregation. These qualities make these solid solutions excellent substitutes\nfor PmScO3 and EuScO3.",
        "positive": "Inverse Spin Hall Effect in nanometer-thick YIG/Pt system: High quality nanometer-thick (20 nm, 7 nm and 4 nm) epitaxial YIG films have\nbeen grown on GGG substrates using pulsed laser deposition. The Gilbert damping\ncoefficient for the 20 nm thick films is 2.3 x 10-4 which is the lowest value\nreported for sub-micrometric thick films. We demonstrate Inverse spin Hall\neffect (ISHE) detection of propagating spin waves using Pt. The amplitude and\nthe lineshape of the ISHE voltage correlate well to the increase of the Gilbert\ndamping when decreasing thickness of YIG. Spin Hall effect based\nloss-compensation experiments have been conducted but no change in the\nmagnetization dynamics could be detected."
    },
    {
        "anchor": "Extremely large magnetoresistance and ultrahigh mobility in the\n  topological Weyl semimetal NbP: Recent experiments have revealed spectacular transport properties of\nconceptually simple semimetals. For example, normal semimetals (e.g. WTe$_2$)\nhave started a new trend to realize a large magnetoresistance, which is the\nchange of electrical resistance by an external magnetic field. Weyl semimetal\n(WSM) is a topological semimetal with massless relativistic electrons as the\nthree-dimensional analogue of graphene and promises exotic transport properties\nand surface states, which are different from those of the famous topological\ninsulators (TIs). In this letter, we choose to utilize NbP in magneto-transport\nexperiments because its band structure is on assembly of a WSM and a normal\nsemimetal. Such a combination in NbP indeed leads to the observation of\nremarkable transport properties, an extremely large magnetoresistance of\n850,000 % at 1.85 K (250 % at room temperature) in a magnetic field of 9 T\nwithout any signs of saturation, and ultrahigh carrier mobility of\n5$\\times$10$^6$ cm$^2$ V$^{-1}$ s$^{-1}$ accompanied by strong Shubnikov-de\nHass (SdH) oscillations. NbP presents a unique example to consequent design the\nfunctionality of materials by combining the topological and conventional\nphases.",
        "positive": "Efficient spin excitation via ultrafast damping-like torques in\n  antiferromagnets: Damping effects form the core of many emerging concepts for high-speed\nspintronic applications. Important characteristics such as device switching\ntimes and magnetic domain-wall velocities depend critically on the damping\nrate. While the implications of spin damping for relaxation processes are\nintensively studied, damping effects during impulsive spin excitations are\nassumed to be negligible because of the shortness of the excitation process.\nHerein, we show that, unlike in ferromagnets, ultrafast damping plays a crucial\nrole in antiferromagnets because of their strongly elliptical spin precession.\nIn time-resolved measurements, we find that ultrafast damping results in an\nimmediate spin canting along the short precession axis. The interplay between\nantiferromagnetic exchange and magnetic anisotropy amplifies this canting by\nseveral orders of magnitude towards large-amplitude modulations of the\nantiferromagnetic order parameter. This leverage effect discloses a highly\nefficient route towards the ultrafast manipulation of magnetism in\nantiferromagnetic spintronics."
    },
    {
        "anchor": "On the origin of multi-component bulk metallic glasses: Atomic size\n  mismatches and de-mixing: The critical cooling rate $\\mathcal{R}_c$, below which liquids crystallize\nupon cooling, characterizes the glass-forming ability (GFA) of the system.\nWhile pure metals are typically poor glass formers with $\\mathcal\n{R}_c>10^{12}\\, {\\rm K/s}$, specific multi-component alloys can form bulk\nmetallic glasses (BMGs) even at cooling rates below $\\mathcal {R}\\sim 1\\, {\\rm\nK/s}$. Conventional wisdom asserts that metal alloys with three or more\ncomponents are better glass formers (with smaller ${\\cal R}_c$) than binary\nalloys. However, there is currently no theoretical framework that provides\nquantitative predictions for $\\mathcal{R}_c$ for multi-component alloys. We\nperform simulations of ternary hard-sphere systems, which have been shown to be\naccurate models for the glass-forming ability of BMGs, to understand the roles\nof geometric frustration and demixing in determining $\\mathcal {R}_c$.\nSpecifically, we compress ternary hard sphere mixtures into jammed packings and\nmeasure the critical compression rate, below which the system crystallizes, as\na function of the diameter ratios $\\sigma_B/\\sigma_A$ and $\\sigma_C/\\sigma_A$\nand number fractions $x_A$, $x_B$, and $x_C$. We find two distinct regimes for\nthe GFA in parameter space for ternary hard spheres. When the diameter ratios\nare close to $1$, such that the largest ($A$) and smallest ($C$) species are\nwell-mixed, the GFA of ternary systems is no better than that of the optimal\nbinary glass former. However, when $\\sigma_C/\\sigma_A \\lesssim 0.8$ is below\nthe demixing threshold for binary systems, adding a third component $B$ with\n$\\sigma_C < \\sigma_B < \\sigma_A$ increases the GFA of the system by preventing\ndemixing of $A$ and $C$. Analysis of the available data from experimental\nstudies indicates that most ternary BMGs are below the binary demixing\nthreshold with $\\sigma_C/\\sigma_A < 0.8$.",
        "positive": "Limits on the amplification of evanescent waves of left-handed materials: We investigate the transfer function of the discretized perfect lens in\nfinite-difference time-domain (FDTD) and transfer matrix (TMM) simulations; the\nlatter allow to eliminate the problems associated with the explicit time\ndependence in FDTD simulations. We argue that the peak observed in the FDTD\ntransfer function near the maximum parallel momentum $k_{\\|,\\mathrm{max}}$ is\ndue to finite time artifacts. We also find the finite discretization mesh acts\nlike imaginary deviations from $\\mu=\\epsilon=-1$ and leads to a cross-over in\nthe transfer function from constance to exponential decay around\n$k_{\\|,\\mathrm{max}}$ limiting the attainable super-resolution. We propose a\nsimple qualitative model to describe the impact of the discretization.\n$k_{\\|,\\mathrm{max}}$ is found to depend logarithmically on the mesh constant\nin qualitative agreement with the TMM simulations."
    },
    {
        "anchor": "In situ monitoring of atomic layer epitaxy via optical ellipsometry: We report on the use of time-resolved optical ellipsometry to monitor the\ndeposition of single atomic layers with subatomic sensitivity.\nRuddlesden-Popper thin films of SrO(SrTiO3)n=4 were grown by means of\nmetalorganic aerosol deposition in the atomic layer epitaxy mode on\nSrTiO3(100), LSAT(100) and DyScO3(110) substrates. The measured time\ndependences of ellipsometric angles, ${\\Delta}(t)$ and ${\\Psi}(t)$, were\ndescribed by using a simple optical model, considering the sequence of atomic\nlayers SrO and TiO2 with corresponding bulk refractive indices. As a result,\nvaluable online information on the growth process, the film structure and\ndefects were obtained. Ex situ characterization techniques, i.e. transmission\nelectron microscopy (TEM), X-ray diffraction (XRD) and X- ray reflectometry\n(XRR) verify the crystal structure and confirm the predictions of optical\nellipsometry.",
        "positive": "Reconstruction of the interatomic forces from dynamic Scanning\n  Transmission Electron Microscopy data: We explore the possibility for the reconstruction of the generative physical\nmodels describing interactions between atomic units in solids from\nobservational electron microscopy data. Here, scanning transmission electron\nmicroscopy (STEM) is used to observe the dynamic motion of Si atoms at the edge\nof monolayer graphene under continuous electron beam illumination. The\nresulting time-lapsed STEM images represent the snapshots of observed chemical\nstates of the system. We use two approaches: potential of mean force (PMF)\ncalculation using a radial distribution function (RDF) and a direct fitting of\nthe graphene-Si interatomic pair-wise potentials with force matching, to\nreconstruct the force fields in the materials. These studies lay the foundation\nfor quantitative analysis of materials energetics from STEM data through the\nsampling of the metastable states in the chemical space of the system."
    },
    {
        "anchor": "Interplay between alloying and tramp element effects on temper\n  embrittlement in bcc iron: DFT and thermodynamic insights: The details of the temper embrittlement mechanism in steels caused by\nimpurities are unknown. Especially from an atomistic point of view, there are\nstill open questions regarding their interactions with alloying elements such\nas Ni, Cr, and Mo. Therefore, we used density functional theory to investigate\nthe segregation and co-segregation behavior and the resulting influence on the\ncohesion of three representative tilt grain boundaries in iron. The results are\nimplemented in a multi-site and multi-component kinetic and thermodynamic model\nfor grain boundary segregation, to gain insights into the temporal and final\ngrain boundary coverage. Our results show that the segregation tendency of As,\nSb, and Sn is stronger than that of the alloying elements and significantly\nmitigates the grain boundary cohesion. Depending on the GB type, interactions\nbetween Sb and Sn vary from negligible to strongly attractive, which increases\nthe likelihood of co-segregation. The cohesion-weakening effect is further\namplified when elements such as Sb, Sn, and As co-segregate, compared to their\nindividual segregation. In contrast, the co-segregation of Ni and Cr does not\nsignificantly increase the enrichment of impurities at grain boundaries, and\ntheir impact on cohesion is found to be negligible. The ability of Mo to\nmitigate reversible temper embrittlement is primarily attributed to its\ncohesion-enhancing effect and its capability to repel tramp elements from GBs,\nrather than scavenging them within the bulk, as suggested by previous\nliterature.",
        "positive": "Lanthanum-Cerium Based Bulk Metallic Glasses with Superior Glass-Forming\n  Ability: A quinary (La0.5Ce0.5)65Al10(Co0.6Cu0.4)25 alloy with superior glass-forming\nability (GFA), identified by the formation of fully glassy rod of 32 mm in\ndiameter by tilt-pour casting, was reported. By comparing with the GFA of\nquarternary (La0.5Ce0.5)65Al10TM25 and ternary Ln65Al10TM25 alloys (Ln = La or\nCe; TM = Co or Cu), we suggest that the strong frustration of crystallization\nby utilizing the coexistence of La-Ce and Co-Cu to complicate competing\ncrystalline phases is helpful to construct BMG component with superior GFA."
    },
    {
        "anchor": "Some aspects of diffracted waves formation at RHEED on a reconstructed\n  crystal face: The evolution of RHEED reflexes intensity during reconstructed transitions\ncharacterizes (often implicitly) reconstructed surface state peculiarities. The\napproaches of a correct RHEED data interpretation, aimed at obtaining\ninformation about reconstructed transitions kinetics, are considered in the\npresent work. In particular, the nature of RHEED reflexes formation, depending\non such parameters as the average size of reconstructed domains and number of\nsuch domains per area unit, is analyzed within the kinematic approximation of\nthe diffraction theory. This geometrical description is a convenient and\neffective (productive) way of analyzing reconstructed transitions mechanisms\nand parameters. The transformation of the functional dependence between the\nmeasured values (RHEED reflexes intensity picture) and the degree of surface\ncoverage by reconstruction domains, at a change of these domains average size\nand distribution density, is shown. This work provides the community with a\nuseful framework for such type of theoretical studies.",
        "positive": "Ultrathick MA$_2$N$_4$(M'N) Intercalated Monolayers with\n  Sublayer-Protected Fermi Surface Conduction States: Interconnect and Metal\n  Contact Applications: Recent discovery of ultrathick $\\mathrm{MoSi_2N_4(MoN)_n}$ monolayers open up\nan exciting platform to engineer 2D material properties via intercalation\narchitecture. Here we computationally investigate a series of ultrathick\nMA$_2$N$_4$(M'N) monolayers (M, M' = Mo, W; A = Si, Ge) under both homolayer\nand heterolayer intercalation architectures in which the same and different\nspecies of transition metal nitride inner core layers are intercalated by outer\npassivating nitride sublayers, respectively. The MA$_2$N$_4$(M'N) monolayers\nare thermally, dynamically and mechanically stable with excellent mechanical\nstrength and metallic properties. Intriguingly, the metallic states around\nFermi level are localized within the inner core layers. Carrier conduction\nmediated by electronic states around the Fermi level is thus spatially\ninsulated from the external environment by the native outer nitride sublayers,\nsuggesting the potential of MA$_2$N$_4$(M'N) in back-end-of-line (BEOL) metal\ninterconnect applications. Nitrogen vacancy defect at the outer sublayers\ncreates `punch through' states around the Fermi level that bridges the carrier\nconduction in the inner core layers and the outer environment, forming a\nelectrical contact akin to the `vias' structures of metal interconnects. We\nfurther show that MoSi$_2$N$_4$(MoN) can serve as a quasi-Ohmic contact to 2D\nWSe$_2$. These findings reveal the promising potential of ultrathick\nMA$_2$N$_4$(MN) monolayers as metal electrodes and BEOL interconnect\napplications."
    },
    {
        "anchor": "Crystal plasticity as a mean field depinning transition: results from a\n  phase field crystal model: Until now, most of our knowledge about the universality class of crystal\nplasticity has come from simulations using discrete dislocation dynamics. These\nare force-controlled, typically at zero temperature, and deal with the creation\nand annihilation of dislocations phenomenologically. In this work, we go beyond\nthese limitations by using phase field crystal simulations in two dimensions at\nfinite temperature to extract the avalanche statistics of a simulated crystal\nunder constant shear velocity. In addition to the avalanche size and energy\ndistributions we extract the avalanche duration distributions and power\nspectra. All exponents and scaling functions extracted here for the statics and\ndynamics of crystal plasticity, belong to the mean field elastic depinning\nuniversality class, confirming earlier findings based on discrete dislocation\ndynamics.",
        "positive": "Strong enhancement of direct magnetoelectric effect in strained\n  ferroelectric-ferromagnetic thin-film heterostructures: The direct magnetoelectric (ME) effect resulting from the polarization\nchanges induced in a ferroelectric film by the application of a magnetic field\nto a ferromagnetic substrate is described using the nonlinear thermodynamic\ntheory. It is shown that the ME response strongly depends on the initial strain\nstate of the film. The ME polarization coefficient of the heterostructures\ninvolving Terfenol-D substrates and compressively strained lead zirconate\ntitanate (PZT) films, which stabilize in the out-of-plane polarization state,\nis found to be comparable to that of bulk PZT/Terfenol-D laminate composites.\nAt the same time, the ME voltage coefficient reaches a giant value of 50 V/(cm\nOe), which greatly exceeds the maximum observed static ME coefficients of bulk\ncomposites. This remarkable feature is explained by a favorable combination of\nconsiderable strain sensitivity of polarization and a low electric permittivity\nin compressively strained PZT films. The theory also predicts a further\ndramatic increase of ME coefficients at the strain-induced transitions between\ndifferent ferroelectric phases."
    },
    {
        "anchor": "Twister: Construction and structural relaxation of commensurate moir\u00e9\n  superlattices: Introduction of a twist between layers of two-dimensional materials which\nleads to the formation of a moir\\'e pattern is an emerging pathway to tune the\nelectronic, vibrational and optical properties. The fascinating properties of\nthese systems is often linked to large-scale structural reconstruction of the\nmoir\\'e pattern. Hence, an essential first step in the theoretical study of\nthese systems is the construction and structural relaxation of the atoms in the\nmoir\\'e superlattice. We present the Twister package, a collection of tools\nthat constructs commensurate superlattices for any combination of 2D materials\nand also helps perform structural relaxations of the moir\\'e superlattice.\nTwister constructs commensurate moir\\'e superlattices using the coincidence\nlattice method and provides an interface to perform structural relaxations\nusing classical forcefields.",
        "positive": "Layer-Polarized Anomalous Hall Effect in Valleytronic van der Waals\n  Bilayers: Layer-polarized anomalous Hall effect (LP-AHE), derived from the coupling\nbetween Berry curvature and layer degree of freedom, is of importance for both\nfundamental physics and device applications. Nonetheless, the current research\nparadigm is rooted in topological systems, rendering such phenomenon rather\nscarce. Here, through model analysis, we propose an alternative, but general\nmechanism to realize the LP-AHE in valleytronic van der Waals bilayers by\ninterlayer sliding. The interaction between the out-of-plane ferroelectricity\nand A-type antiferromagnetism gives rise to the layer-locked Berry curvature\nand thus the long-sought LP-AHE in the bilayer systems. The LP-AHE can be\nstrongly coupled with sliding ferroelectricity, to enable ferroelectrically\ncontrollable and reversible. The mechanism is demonstrated in a series of real\nvalleytronic materials, including bilayer VSi2P4, VSi2N4, FeCl2, RuBr2 and\nVClBr. The new mechanism and phenomena provide a significant new direction to\nrealize LP-AHE and explore its application in electronics."
    },
    {
        "anchor": "Coexistence of tetrahedral and octahedral-like sites in amorphous phase\n  change materials: Chalcogenide alloys are materials of interest for optical recording and\nnon-volatile memories. We perform ab-initio molecular dynamics simulations\naiming at shading light onto the structure of amorphous Ge2Sb2Te5 (GST), the\nprototypical material in this class. First principles simulations show that\namorphous GST obtained by quenching from the liquid phase displays two types of\nshort range order. One third of Ge atoms are in a tetrahedral environment while\nthe remaining Ge, Sb and Te atoms display a defective octahedral environment,\nreminiscent of cubic crystalline GST.",
        "positive": "Variable-amplitude oscillatory shear response of amorphous materials: Variable-amplitude oscillatory shear tests are emerging as powerful tools to\ninvestigate and quantify the nonlinear rheology of amorphous solids, complex\nfluids and biological materials. Quite a few recent experimental and atomistic\nsimulation studies demonstrated that at low shear amplitudes, an amorphous\nsolid settles into an amplitude- and initial conditions-dependent dissipative\nlimit cycle, in which back-and-forth localized particle rearrangements\nperiodically bring the system to the same state. At sufficiently large shear\namplitudes, the amorphous system loses memory of the initial conditions,\nexhibits chaotic particle motions accompanied by diffusive behavior and settles\ninto a stochastic steady-state. The two regimes are separated by a transition\namplitude, possibly characterized by some critical-like features. Here we argue\nthat these observations support some of the physical assumptions embodied in\nthe nonequilibrium thermodynamic, internal-variables based,\nShear-Transformation-Zone model of amorphous visco-plasticity; most notably\nthat \"flow defects\" in amorphous solids are characterized by internal states\nbetween which they can make transitions, and that structural evolution is\ndriven by dissipation associated with plastic deformation. We present a rather\nextensive theoretical analysis of the thermodynamic Shear-Transformation-Zone\nmodel for a variable-amplitude oscillatory shear protocol, highlighting its\nsuccess in accounting for various experimental and simulational observations,\nas well as its limitations. Our results offer a continuum-level theoretical\nframework for interpreting the variable-amplitude oscillatory shear response of\namorphous solids and may promote additional developments."
    },
    {
        "anchor": "Negative bulk modulus and possibility of loss of elastic stability near\n  tricritical transitions in thin films on substrates: Within the Landau-like approach we study anomalies of elastic moduli at phase\ntransitions in thin films on substrates. We consider the case where, similar to\nmany experimental cases, the first-order transition in free crystal would\nconvert into a second order in the film if the system remained homogeneous. It\nis shown, however, that apart from its questionable thermodynamic\nprofitability, the homogeneous state of low-symmetry phase may become\nabsolutely unstable which is signaled by changing of sign of its bulk modulus.",
        "positive": "Magnetic anisotropy of vicinal (001) fcc Co films: role of crystal\n  splitting and structure relaxation in step-decoration effect: The uniaxial in-plane magnetic anisotropy (UIP-MA) constant is calculated for\na single step on the (001) surface of fcc Co($N$) films. The calculations are\ndone for both an undecorated step and the step decorated with one or more, up\nto 7, Cu wires. Our objective is to explain the mechanisms by which the\ndecoration decreases the UIP-MA constant, which is the effect observed\nexperimentally for ultrathin Co films deposited on vicinal (001) Cu surfaces\nand can lead to reorientation of magnetization within the film plane.\nTheoretical calculations performed with a realistic tight-binding model show\nthat the step decoration changes the UIP-MA constant significantly only if the\nsplitting between the on-site energies of various $d$-orbitals is included for\natoms located near the step edge. The local relaxation of atomic structure\naround the step is also shown to have a significant effect on the shift of the\nUIP-MA constant. The influence of these two relevant factors is analyzed\nfurther by examining individual contributions to the UIP-MA constant from atoms\naround the step. The magnitude of the obtained UIP-MA shift agrees well with\nexperimental data. It is also found that an additional shift due to possible\ncharge transfer between Cu and Co atoms is very small."
    },
    {
        "anchor": "Strain effects on Phase-Filling Singularities in Highly Doped n-Type Ge: Recently, Chi Xu et al. predicted the phase-filling singularities (PFS) in\nthe optical dielectric function (ODF) of the highly doped $n$-type Ge and\nconfirmed in experiment the PFS associated $E_{1}+\\Delta_{1}$ transition by\nadvanced \\textit{in situ} doping technology [Phys. Rev. Lett. 118, 267402\n(2017)], but the strong overlap between $E_{1}$ and $E_{1}+\\Delta_{1}$ optical\ntransitions made the PFS associated $E_{1}$ transition that occurs at the high\ndoping concentration unobservable in their measurement. In this work, we\ninvestigate the PFS of the highly doped n-type Ge in the presence of the\nuniaxial and biaxial tensile strain along [100], [110] and [111] crystal\norientation. Compared with the relaxed bulk Ge, the tensile strain along [100]\nincreases the energy separation between the $E_{1}$ and $E_{1}+\\Delta_{1}$\ntransition, making it possible to reveal the PFS associated $E_{1}$ transition\nin optical measurement. Besides, the application of tensile strain along [110]\nand [111] offers the possibility of lowering the required doping concentration\nfor the PFS to be observed, resulting in new additional features associated\nwith $E_{1}+\\Delta_{1}$ transition at inequivalent $L$-valleys. These\ntheoretical predications with more distinguishable optical transition features\nin the presence of the uniaxial and biaxial tensile strain can be more\nconveniently observed in experiment, providing new insights into the excited\nstates in heavily doped semiconductors.",
        "positive": "Paramagnetic molecule induced strong antiferromagnetic exchange coupling\n  on a magnetic tunnel junction based molecular spintronics device: This paper reports our Monte Carlo (MC) studies aiming to explain the\nexperimentally observed paramagnetic molecule induced antiferromagnetic\ncoupling between the ferromagnetic (FM) electrodes. Recently developed magnetic\ntunnel junction based molecular spintronics devices (MTJMSDs), which were\nprepared by chemically bonding the paramagnetic molecules between the FM\nelectrodes along the exposed side edges of magnetic tunnel junctions, exhibited\nmolecule induced strong antiferromagnetic coupling. Our MC studies focused on\nthe atomic model analogous to the MTJMSD and studied the effect of molecules\nmagnetic couplings with the two FM electrodes. Simulations show that when a\nmolecule established ferromagnetic coupling with one electrode and\nantiferromagnetic coupling with the other electrode then theoretical results\neffectively explained the experimental findings. MC and experimental studies\nsuggest that the strength of exchange coupling between molecule and FM\nelectrode should be 50 percent of the interatomic exchange coupling strength of\nthe FM electrodes."
    },
    {
        "anchor": "Anomalous and normal dependence of the sound velocity in the liquid\n  Bi-Sb system: The sound velocity in selected liquid alloys of the isomorphous Bi-Sb system\nwas measured as a function of temperature to a high accuracy of 0.2%. The sound\nvelocity temperature coefficient, dlnc/dT, at the liquidus is found to vary\nnon-monotonously as a function of alloy composition, with the transition from\nnormal to anomalous temperature dependence occurring at a composition of\napproximately Bi35Sb65. Beyond this composition up to approximately Bi10Sb90\nthe sound velocity is found to be temperature independent over a wide range.\nThe deviation of the sound velocity from that expected in an ideal solution is\nfound to be dominated by a sub-regular interaction. The present measurements\nallow the determination of the pressure dependence of the sub-regular solution\ninteraction parameters and are found to be consistent with high pressure\nstudies of the phase diagram in this system. The sound velocity is shown to be\nan effective measure of the pressure dependence of the alloy interactions.",
        "positive": "Ni-doped epitaxial graphene monolayer on the Ni(111) surface: Nickel-doped graphene has been synthesized from propylene on a Ni(111)\nsurface and studied using scanning tunneling microscopy (STM) and density\nfunctional theory (DFT). It is established that nickel centers are formed\nduring graphene synthesis on the Ni(111) surface by both chemical vapor\ndeposition (CVD) and temperature-programmed growth (TPG); apparently, they are\nalways present in graphene synthesized on Ni(111). The centers are observed in\nSTM images as single defects or defect chains and identified by DFT\ncalculations as Ni atoms in carbon bivacancies. These nickel atoms are\npositively charged and may be of interest for single-atom catalysis. The\nincorporated Ni atoms should remain in graphene after the detachment from the\nsubstrate since they bound more strongly with carbon atoms in graphene than\nwith substrate nickel atoms."
    },
    {
        "anchor": "Searching for high magnetization density in bulk Fe: the new metastable\n  Fe$_6$ phase: We report the discovery of a new allotrope of iron by first principles\ncalculations. This phase has $Pmn2_1$ symmetry, a six-atom unit cell (hence the\nname Fe$_6$), and the highest magnetization density (M$_s$) among all known\ncrystalline phases of iron. Obtained from the structural optimizations of the\nFe$_3$C-cementite crystal upon carbon removal, $Pmn2_1$ Fe$_6$ is shown to\nresult from the stabilization of a ferromagnetic FCC phase, further strained\nalong the Bain path. Although metastable from 0 to 50 GPa, the new phase is\nmore stable, at low pressures, than the other well-known HCP and FCC allotropes\nand smoothly transforms into the FCC phase under compression. If stabilized to\nroom temperature, e.g., by interstitial impurities, Fe$_{6}$ could become the\nbasis material for high M$_s$ rare-earth-free permanent magnets and high-impact\napplications such as, light-weight electric engine rotors or high-density\nrecording media. The new phase could also be key to explain the enigmatic high\nM$_s$ of Fe$_{16}$N$_2$, which is currently attracting an intense research\nactivity.",
        "positive": "Terahertz emission from transient currents and coherent phonons in\n  layered MoSe$_2$ and WSe$_2$: Terahertz (THz) time-domain emission spectroscopy was performed on layered\n2H-MoSe2 and 2H-WSe2. The THz emission shows an initial cycle attributed to\nsurge currents and is followed by oscillations attributed to coherent\ninterlayer phonon modes. To obtain the frequencies of the interlayer\nvibrations, analysis of the THz emission waveforms were performed, separating\nthe two contributions to the total waveform. Results of the fitting show\nseveral vibrational modes in the range of 5.87 to 32.75 cm-1 for the samples,\nattributed to infrared-active interlayer shear and breathing modes. This study\ndemonstrates that THz emission spectroscopy provides a means of observing these\nlow frequency vibrational modes in layered materials."
    },
    {
        "anchor": "Wavefront depinning transition in discrete one-dimensional\n  reaction-diffusion systems: Pinning and depinning of wavefronts are ubiquitous features of spatially\ndiscrete systems describing a host of phenomena in physics, biology, etc. A\nlarge class of discrete systems is described by overdamped chains of nonlinear\noscillators with nearest-neighbor coupling and controlled by constant external\nforces. A theory of the depinning transition for these systems, including\nscaling laws and asymptotics of wavefronts, is presented and confirmed by\nnumerical calculations.",
        "positive": "Polarization fluctuation dominated electrical transport processes of\n  polymer based ferroelectric-field-effect transistors: Ferroelectric field-effect transistors (FE-FETs) consisting of tunable\ndielectric layers are utilized to investigate interfacial transport processes.\nLarge changes in the dielectric constant as a function of temperature are\nobserved in FE-FETs in conjunction with the ferroelectric to paraelectric\ntransition. The devices offer a test bed to evaluate specific effects of\npolarization on the electrical processes. FE-FETs have dominant contributions\nfrom polarization-fluctuation rather than static dipolar disorder prevalent in\nhigh k paraelectric dielectric-based FETs. Additionally, photo-excitation\nmeasurements in the depletion mode reveal clear features in the FET response at\ndifferent temperatures, indicative of different transport regimes."
    },
    {
        "anchor": "Vacancy defect positron lifetimes in strontium titanate: The results of positron annihilation lifetime spectroscopy measurements on\nundoped, electron irradiated, and Nb doped SrTiO3 single crystals are reported.\nPerfect lattice and vacancy defect positron lifetimes were calculated using two\ndifferent first-principles schemes. The Sr vacancy defect related positron\nlifetime was obtained from measurements on Nb doped, electron irradiated, and\nvacuum annealed samples. Undoped crystals showed a defect lifetime component\ndominated by trapping to Ti vacancy related defects.",
        "positive": "Toward Realistic Amorphous Topological Insulators: The topological properties of materials are, until now, associated with the\nfeatures of their crystalline structure, although translational symmetry is not\nan explicit requirement of the topological phases. Recent studies of hopping\nmodels on random lattices have demonstrated that amorphous model systems show a\nnontrivial topology. Using {\\it ab initio} calculations we show that\ntwo-dimensional amorphous materials can also display topological insulator\nproperties. More specifically, we present a realistic state-of-the-art study of\nthe electronic and transport properties of amorphous bismuthene systems,\nshowing that these materials are topological insulators. These systems are\ncharacterized by the topological index $\\mathbb{Z}_{2}=1$ and bulk-edge\nduality, and their linear conductance is quantized, ${\\cal G}=2e^{2}/h$, for\nFermi energies within the topological gap. Our study opens the path to the\nexperimental and theoretical investigation of amorphous topological insulator\nmaterials."
    },
    {
        "anchor": "Magnetic relaxation in a model of interacting nanoparticles in terms of\n  microscopic energy barriers: Monte Carlo simulations are used to study the magnetic relaxation of a system\nof single domain particles with dipolar interactions modeled by a chain of\nHeisenberg classical spins. We show that the so-called $T\\ln(t/\\tau_0)$ method\ncan be extended to interacting systems and how, from the computed master\nrelaxation curves, the effective energy barrier distributions responsible for\nthe relaxation can be obtained. A transition from a quasi-logarithmic to\npower-law behavior of the relaxation as the interaction strength is in-creased\nis found. By direct computation of the effective energy barriers of the system,\nwe show that this is due to the appearance of an increasing number of small\nenergy barriers caused by the reduction of the anisotropy energy barriers as\nthe local dipolar fields increase.",
        "positive": "Large magnetic anisotropy in Ferrihydrite nanoparticles synthesized from\n  reverse micelles: Six-line ferrihydrite(FH) nanoparticles have been synthesized in the core of\nreverse micelles, used as nanoreactors to obtain average particle sizes $<d>$\n$\\approx$ 2 to 4 nm. The blocking temperatures $T_B^m$ extracted from\nmagnetization data increased from $\\approx 10$ to 20 K for increasing particle\nsize. Low-temperature \\MOS measurements allowed to observe the onset of\ndifferentiated contributions from particle core and surface as the particle\nsize increases. The magnetic properties measured in the liquid state of the\noriginal emulsion showed that the \\FH phase is not present in the liquid\nprecursor, but precipitates in the micelle cores after the free water is\nfreeze-dried. Systematic susceptibility $\\chi_{ac}(\\emph{f},T)$ measurements\nshowed the dependence of the effective magnetic anisotropy energies $E_{a}$\nwith particle volume, and yielded an effective anisotropy value of $K_{eff} =\n312\\pm10$ kJ/m$^3$."
    },
    {
        "anchor": "The high-pressure high-temperature phase diagram of calcium fluoride\n  from classical atomistic simulations: We study the phase diagram of calcium fluoride (CaF2) under pressure using\nclassical molecular dynamic simulations performed with a simple pairwise\ninteratomic potential of the Born-Mayer-Huggings form. Our results obtained\nunder conditions 0 < P < 20 GPa and 0 < T < 4000 K reveal a rich variety of\nmulti-phase boundaries involving different crystal, superionic and liquid\nphases, for all which we provide an accurate parametrization. Interestingly, we\npredict the existence of three special triple points (i.e.\nsolid-solid-superionic, solid-superionic-superionic and\nsuperionic-superionic-liquid coexisting states) within a narrow and\nexperimentally accessible thermodynamic range of 6 < P < 8 GPa and 1500 < T <\n2750 K. Also, we examine the role of short-ranged repulsive (SR) and\nlong-ranged attractive (LA) atomic interactions in the prediction of melting\nlines with the finding that SR Ca-F and LA F-F contributions are most decisive.",
        "positive": "Impact of electron solvation on ice structures at the molecular scale: We determine the impact of electron solvation on D$_2$O structures adsorbed\non Cu(111) with low temperature scanning tunneling microscopy, two-photon\nphotoemission, and ab initio theory. UV photons generating solvated electrons\nlead not only to transient, but also to permanent structural changes through\nthe rearrangement of individual molecules. The persistent changes occur near\nsites with a high density of dangling OH groups that facilitate electron\nsolvation. We conclude that energy dissipation during solvation triggers\npermanent molecular rearrangement via vibrational excitation."
    },
    {
        "anchor": "Deterministic Covalent Organic Functionalization of Monolayer Graphene\n  with 1,3-Dipolar Cycloaddition Via High Resolution Surface Engineering: Spatially-resolved organic functionalization of monolayer graphene is\nsuccessfully achieved by combining low-energy electron beam irradiation with\n1,3-dipolar cycloaddition of azomethine ylide. Indeed, the modification of the\ngraphene honeycomb lattice obtained via electron beam irradiation yields to a\nlocal increase of the graphene chemical reactivity. As a consequence, thanks to\nthe high-spatially resolved generation of structural defects (~ 100 nm),\nchemical reactivity patterning has been designed over the graphene surface in a\nwell-controlled way. Atomic force microscopy and Raman spectroscopy allow to\ninvestigate the two-dimensional spatial distribution of the structural defects\nand the new features that arise from the 1,3-dipolar cycloaddition, confirming\nthe spatial selectivity of the graphene functionalization achieved via defect\nengineering. The Raman signature of the functionalized graphene is investigated\nboth experimentally and via ab initio molecular dynamics simulations, computing\nthe power spectrum. Furthermore, the organic functionalization is shown to be\nreversible thanks to the desorption of the azomethine ylide induced by focused\nlaser irradiation. The selective and reversible functionalization of high\nquality graphene using 1,3-dipolar cycloaddition is a significant step towards\nthe controlled synthesis of graphene-based complex structures and devices at\nthe nanoscale.",
        "positive": "interface_master: Python package building CSL and approximate CSL\n  interfaces of any two lattices -- an effective tool for interface engineers: Crystalline interfaces are of highly importance in many practical\napplications. To conduct effective simulation and analysis for coincident site\nlattice (CSL) interfaces, effective programmes are of high demand in building\ntheir CSL bicrystal models to apply periodic boundary condition. The existing\nreported programmes capable suffer from problems including limitation of\navailable lattice, poor capability for making heterogeneous interfaces and\nrequirement of none-intuitive input parameters which cannot be directly\nobtained from an experimental observation result for an interface. This work\npresents a python programme to construct bicrystal model of interfaces\nconsisting of any two lattices, including tilt, twist, mixed, and hetero\ninterfaces and surfaces, which will support in effective simulation and\nanalysis of crystalline interfaces."
    },
    {
        "anchor": "Effect of Dynamic Surface Polarization on the Oxidative Stability of\n  Solvents in Nonaqueous Li-O$_2$ Batteries: Polarization-induced renormalization of the frontier energy levels of\ninteracting molecules and surfaces can cause significant shifts in the\nexcitation and transport behavior of electrons. This phenomenon is crucial in\ndetermining the oxidative stability of nonaqeous electrolytes in high energy\ndensity electrochemical systems such as the Li-O$_2$ battery. On the basis of\npartially self-consistent first-principles ScGW0 calculations, we\nsystematically study how the electronic energy levels of four commonly used\nsolvent molecules, namely dimethylsulfoxide (DMSO), dimethoxyethane (DME),\ntetrahydrofuran (THF) and acetonitrile (ACN), renormalize when physisorbed on\nthe different stable surfaces of Li$_2$O$_2$, the main discharge product. Using\nband level alignment arguments, we propose that the difference between the\nsolvent's highest occupied molecular orbital (HOMO) level and the surface's\nvalence band maximum (VBM) is a refined metric of oxidative stability. This\nmetric and a previously used descriptor, solvent's gas phase HOMO level, agree\nquite well for physisorbed cases on pristine surfaces where ACN is oxidatively\nmost stable followed by DME, THF and DMSO. However, this effect is\nintrinsically linked to the surface chemistry of solvent's interaction with the\nsurfaces states and defects, and depends strongly on their nature. We\nconclusively show that the propensity of solvent molecules to oxidize will be\nsignificantly higher on Li$_2$O$_2$ surfaces with defects as compared to\npristine surfaces. This suggests that the oxidatively stability of solvent is\ndynamic and is a strong function of surface electronic properties. Thus, while\ngas phase HOMO levels could be used for preliminary solvent candidate\nscreening, a more refined picture of solvent stability requires mapping out the\nsolvent stability as a function of the state of the surface under the operating\nconditions.",
        "positive": "Atomistic simulations of self-trapped exciton formation in silicon\n  nanostructures: The transition from quantum dots to nanowires: Using an approximate time-dependent density functional theory method, we\ncalculate the absorption and luminescence spectra for hydrogen passivated\nsilicon nanoscale structures with large aspect ratio. The effect of electron\nconfinement in axial and radial directions is systematically investigated.\nExcited state relaxation leads to significant Stokes shifts for short nanorods\nwith lengths less than 2 nm, but has little effect on the luminescence\nintensity. The formation of self-trapped excitons is likewise observed for\nshort nanostructures only; longer wires exhibit fully delocalized excitons with\nneglible geometrical distortion at the excited state minimum."
    },
    {
        "anchor": "Analysis of the excited-state absorption spectral bandshape of\n  oligofluorenes: We present ultrafast transient absorption spectra of two oligofluorene\nderivatives in dilute solution. These spectra display clear vibronic structure,\nwhich we analyze rigorously using a time-dependent formalism of absorption to\nextract the principal excited-state vibrational normal-mode frequencies that\ncouple to the electronic transition, the configurational displacement of the\nhigher-lying excited state, and the reorganization energies. We can model the\nexcited-state absorption spectrum using two totally symmetric vibrational modes\nwith frequencies 450 (dimer) or 400 cm$^{-1}$ (trimer), and 1666 cm$^{-1}$. The\nreorganization energy of the ground-state absorption is rather insensitive to\nthe oligomer length at 230 meV. However, that of the excited-state absorption\nevolves from 58 to 166 meV between the oligofluorene dimer and trimer. Based on\nprevious theoretical work [Shukla et al., Phys. Rev. B \\textbf{67}, 245203\n(2003)], we assign the absorption spectra to a transition from the $1B_u$\nexcited state to a higher-lying $mA_g$ state, and find that the energy of the\nexcited-state transition with respect to the ground-state transition energy is\nin excellent agreement with the theoretical predictions for both oligomers\nstudied here. These results and analysis permit profound understanding of the\nnature of excited-state absorption in $\\pi$-conjugated polymers, which are the\nsubject of general interest as organic semiconductors in the solid state.",
        "positive": "Engineering frictional characteristics of MoS2 structure by tuning\n  thickness and morphology- An atomic, electronic structure, and exciton\n  analysis: We performed atomic and electron dynamics analysis to study the impact of\nmorphological and thickness changes of a MoS2 system on its tribological\nproperties through a diamond tip. We had considered 4 cases: variable layers\n(1-4 layers) and number (2-8 indents), radius (12{\\AA}, 16{\\AA}, 20{\\AA},\n24{\\AA}), and pattern of indents (0{\\deg}, 25{\\deg}, 30{\\deg}, 35{\\deg},\n45{\\deg}, 60{\\deg}) resulting into 18 subcases. MD results showed changing the\nradius and number of indents were the most, and number of layers and indents'\npattern were the least effective way to tune the frictional characteristics.\nGround state ab-initio study demonstrated an increase in the number and radius\nof indents, raising the number of stretched bonds. Consequently, the volume\ncovered by the HOMO iso-surface increases, and that of LUMO decreases. That\nmakes higher area/volume available to lose/share electrons, resulting in\nstronger interlocking between layers and tip. And TD-DFT calculation proves the\nexistence of interfacial excitons, resulting in stronger interlocking between\nthe layer's surface and tip despite a contraction in the LUMO iso-surfaces'\narea/volume. We believe these interlayer excitons result in higher average\nZ-axis(hence frictional force) reaction forces for the indents number subcases\nand lower for indents radius subcases as the number and radius of indents\nincrease."
    },
    {
        "anchor": "First-principles modeling of the Invar effect in Fe65Ni35 by the\n  spin-wave method: Thermal lattice expansion of the Invar Fe65Ni35 alloy is investigated in\nfirst-principles calculations using the spin-wave method, which is generalized\nhere for the ferromagnetic state with short range order. It is shown that\nmagnetic short-range order effects make substantial contribution to the\nequilibrium lattice constant and cannot be neglected in the accurate ab initio\nmodeling of the thermal expansion in Fe-Ni alloys. We also demonstrate that at\nhigh temperatures, close and above the magnetic transition, magnetic entropy\nassociated with transverse and longitudinal spin fluctuations yields a\nnoticeable contribution to the equilibrium lattice constant. The obtained\ntheoretical results for the temperature dependent lattice constant are in\nsemiquantitative agreement with the experimental data apart from the region\nclose the magnetic transition.",
        "positive": "Magnetic ordered structure dependence of magnetic refrigeration\n  efficiency: We have investigated the relation between magnetic ordered structure and\nmagnetic refrigeration efficiency in the Ising model on a simple cubic lattice\nusing Monte Carlo simulations. The magnetic entropy behaviors indicate that the\nprotocol, which was first proposed in [Appl. Phys. Lett. {\\bf 104}, 052415\n(2014).], can produce the maximum isothermal magnetic entropy change and the\nmaximum adiabatic temperature change in antiferromagnets. Furthermore, the\ntotal amount of heat transfer under the proposed protocol reaches a maximum.\nThe relation between measurable physical quantities and magnetic refrigeration\nefficiency is also discussed."
    },
    {
        "anchor": "High-intensity pulsed ion beam treatment of amorphous iron-based metal\n  alloy: Abstract The results of intense pulsed ion beam (IPIB) treatment of the soft\nmagnetic amorphous alloy of a FINEMET-type are presented. Foil produced from\nthe alloy was irradiated with short (about 100 ns) pulses of carbon ions and\nprotons with energy of up to 300 keV and an energy density of up to 7 J/cm2.\nX-ray diffraction, M\\\"ossbauer spectroscopy and magnetic measurements were used\nto investigate structural and magnetic properties of irradiated foils. It is\nshown that the foil remains intact after the treatment, and the crystal\nstructure still amorphous. Spontaneous magnetization vector is found to lie\nalmost along perpendicular to the foil plane after irradiation, whereas for the\ninitial amorphous foil it belongs to the plane. The magnetic properties of the\nfoil undergo changes: the coercive force decreases, the saturation induction\nincreases slightly, and the magnetization curve has shallower slope.",
        "positive": "Development of Interatomic Potentials to Model the Interfacial Heat\n  Transport of Ge/GaAs: Molecular dynamics simulations provide a versatile framework to study\ninterfacial heat transport, but their accuracy remains limited by the accuracy\nof available interatomic potentials. In the past, researchers have adopted the\nuse of analytic potentials and simple mixing rules to model interfacial\nsystems, with minimal justification for their use. On the other hand,\ncontemporary machine learned interatomic potentials have greater complexity,\nbut have not seen rigorous validation of interfacial heat transport properties.\nMoreover, when fitting to ab initio data, it is not known whether interface\nsystems small enough to be tractable for density functional theory calculations\ncan produce reasonable interatomic force constants. These and related questions\nare studied herein using a model Ge/GaAs system, with a particular focus on the\nharmonic force constants (IFC2s) of the interface. The ab initio IFC2s are\nshown to recover near bulk-like values ~ 1-2 nm away from the interface, while\nalso exhibiting a complex relationship across the interface that likely\nprecludes any successful application of mixing rules. Two different spectral\nneighborhood analysis potentials (SNAP) are developed to model the interface.\nOne is fit to the total forces, while the other is only used to describe the\nanharmonicity, with a Taylor expansion used to describe the harmonic portion of\nthe potential. Each potential, along with their merits and issues are compared\nand discussed, which provides important insights for future work."
    },
    {
        "anchor": "Direct observation of altermagnetic band splitting in CrSb thin films: Altermagnetism represents an emergent collinear magnetic phase with\ncompensated order and an unconventional alternating even-parity wave spin order\nin the non-relativistic band structure. We investigate directly this\nunconventional band splitting near the Fermi energy through spinintegrated soft\nX-ray angular resolved photoemission spectroscopy. The experimentally obtained\nangle-dependent photoemission intensity, acquired from epitaxial thin films of\nthe predicted altermagnet CrSb, demonstrates robust agreement with the\ncorresponding band structure calculations. In particular, we observe the\ndistinctive splitting of an electronic band on a low-symmetry path in the\nBrilliouin zone that connects two points featuring symmetry-induced degeneracy.\nThe measured large magnitude of the spin splitting of approximately 0.6 eV and\nthe position of the band just below the Fermi energy underscores the\nsignifcance of altermagnets for spintronics based on robust broken time\nreversal symmetry responses arising from exchange energy scales, akin to\nferromagnets, while remaining insensitive to external magnetic fields and\npossessing THz dynamics, akin to antiferromagnets.",
        "positive": "Friction Force for Self-Excited Systems: The paper presents a model for low friction made up of a self-excited\noscillator sliding along a periodic potential. It is shown that if the\nself-excitation affects a body sliding tangentially to a surface, than\nstick-slip modification and reduction of energy dissipation during the motion\nare observed."
    },
    {
        "anchor": "Quasistatic and Pulsed Current-Induced Switching with Spin-Orbit Torques\n  in Ultrathin Films with Perpendicular Magnetic Anisotropy: Spin-orbit interaction derived spin torques provide a means of reversing the\nmagnetization of perpendicularly magnetized ultrathin films with currents that\nflow in the plane of the layers. A basic and critical question for applications\nis the speed and efficiency of switching with nanosecond current pulses. Here\nwe investigate and contrast the quasistatic (slowly swept current) and pulsed\ncurrent-induced switching characteristics of micron scale Hall crosses\nconsisting of very thin ($<1$ nm) perpendicularly magnetized CoFeB layers on\n$\\beta$-Ta. While complete magnetization reversal is found at a threshold\ncurrent density in the quasistatic case, short duration ($\\leq 10$ ns) larger\namplitude pulses ($\\simeq 10 \\times$ the quasistatic threshold current) lead to\nonly partial magnetization reversal and domain formation. We associate the\npartial reversal with the limited time for reversed domain expansion during the\npulse.",
        "positive": "Ultralow thermal conductivity in two-dimensional MoO$_3$: Monolayer molybdenum trioxide (MoO$_3$) is an emerging two-dimensional (2D)\nmaterial with high electrical conductivity. Using first-principles calculations\nand a Boltzmann transport theoretical framework, we predict record low\nroom-temperature phonon thermal conductivity ($\\kappa_p$) of 1.57 W/mK and 1.26\nW/mK along the principal in-plane directions of MoO$_3$ monolayer. The behavior\nis attributed to the combination of soft flexural and in-plane acoustic modes,\nwhich are coupled through the finite layer thickness, and to the strong bonding\nanharmonicity, which gives rise to significant 3- and 4-phonon scattering\nevents. These insights suggest new indicators for guiding the search of 2D\nmaterials with low $\\kappa_p$. Our result motivates experimental $\\kappa_p$\nmeasurements in MoO$_3$, and its applications as a thermoelectric and thermally\nprotective material."
    },
    {
        "anchor": "Interaction between Injection Points during Hydraulic Fracturing: We present a model of the hydraulic fracturing of heterogeneous poroelastic\nmedia. The formalism is an effective continuum model that captures the coupled\ndynamics of the fluid pressure and the fractured rock matrix and models both\nthe tensile and shear failure of the rock. As an application of the formalism,\nwe study the geomechanical stress interaction between two injection points\nduring hydraulic fracturing (hydrofracking) and how this interaction influences\nthe fracturing process. For injection points that are separated by less than a\ncritical correlation length, we find that the fracturing process around each\npoint is strongly correlated with the position of the neighboring point. The\nmagnitude of the correlation length depends on the degree of heterogeneity of\nthe rock and is on the order of 30-45 m for rocks with low permeabilities. In\nthe strongly correlated regime, we predict a novel effective fracture-force\nthat attracts the fractures toward the neighboring injection point.",
        "positive": "Reflectionless Sharp Bends and Corners in Waveguides Using\n  Epsilon-Near-Zero Effects: Following our recent theoretical and experimental results that show how\nzero-permittivity metamaterials may provide anomalous tunneling and energy\nsqueezing through ultranarrow waveguide channels, here we report an\nexperimental investigation of the bending features relative to this\ncounterintuitive resonant effect. We generate the required effectively-zero\npermittivity using a waveguide operating at the cut-off of its dominant mode,\nand we show how sharp and narrow bends may be inserted within the propagation\nchannel without causing any sensible reflection or loss."
    },
    {
        "anchor": "Stainless Steel Surface Structure and Initial Oxidation at Nanometric\n  and Atomic Scales: The durability of passivable metals and alloys is often limited by the\nstability of the surface oxide film, the passive film, providing\nself-protection against corrosion in aggressive environments. Improving this\nstability requires to develop a deeper understanding of the surface structure\nand initial surface reactivity at the nanometric or atomic scale. In this work\nwe applied scanning tunneling microscopy to unravel the surface structure of a\nmodel stainless steel surface in the metallic state and its local modifications\ninduced by initial reaction in dioxygen gas. The results show a rich and\ncomplex structure of the oxide-free surface with reconstructed atomic lattice\nand self-organized lines of surface vacancies at equilibrium. New insight is\nbrought into the mechanisms of initial oxidation at steps and vacancy injection\non terraces leading to Cr-rich oxide nuclei and locally Cr-depleted terraces,\nimpacting the subsequent mechanism of chromium enrichment essential to the\nstability of the surface oxide.",
        "positive": "Application of the analytical methods REM/EDX, AES and SNMS to a\n  chlorine induced aluminium corrosion: Scanning electron microscopy - SEM - with energy dispersive X-ray detection -\nEDX -, Auger electron spectroscopy - AES - and sputtered neutral mass\nspectrometry - SNMS - have been used to characterize a chlorine induced\ncorrosion of an aluminium metallisation. SEM/EDX detects the characteristic\nX-rays that are emitted from the first few micrometers beneath the specimens\nsurface after inner shell ionisation by the primary electrons. AES detects the\nalternatively ejected Auger electrons that are generated within the topmost\natomic layers of the sample. To obtain elemental concentration depth profiles,\nthe surface layers are removed by ion sputtering. Whereas AES detects the\ncomposition of the remaining surface, SNMS measures sputtered fluxes and does\nnot suffer from preferential sputtering. As demonstrated by the example of a\nchlorine induced aluminium corrosion, these analytical methods are\ncomplementary with respect to quantification, chemical information and\ninformation depth. Only by simultaneous use measuring artefacts are detectable\nand able to be excluded from interpretation."
    },
    {
        "anchor": "The magnetic properties and structure of the quasi-two-dimensional\n  antiferromagnet CoPS$_3$: The magnetic properties and magnetic structure are presented for CoPS$_3$, a\nquasi-two-dimensional antiferromagnet on a honeycomb lattice with a N\\'eel\ntemperature of $T_N \\sim 120$ K. The compound is shown to have XY-like\nanisotropy in its susceptibility, and the anisotropy is analysed to extract\ncrystal field parameters. For temperatures between 2 K and 300 K, no phase\ntransitions were observed in the field-dependent magnetization up to 10 Tesla.\nSingle-crystal neutron diffraction shows that the magnetic propagation vector\nis {\\bf{k}}= $\\left[010\\right]$ with the moments mostly along the $\\mathbf{a}$\naxis and with a small component along the $\\mathbf{c}$ axis, which largely\nverifies the previously-published magnetic structure for this compound. The\nmagnetic Bragg peak intensity decreases with increasing temperature as a power\nlaw with exponent $2\\beta = 0.60 \\pm 0.01$ for $T > 0.9~T_N$.",
        "positive": "Photoinduced electromotive force on the surface of InN epitaxial layers: We report the generation of photo-induced electromotive force (EMF) on the\nsurface of c-axis oriented InN epitaxial films grown on sapphire substrates. It\nhas been found that under the illumination of above band gap light, EMFs of\ndifferent magnitudes and polarities are developed on different parts of the\nsurface of these layers. The effect is not the same as the surface photovoltaic\nor Dember potential effects, both of which result in the development of EMF\nacross the layer thickness, not between different contacts on the surface.\nThese layers are also found to show negative photoconductivity effect.\nInterplay between surface photo-EMF and negative photoconductivity result in a\nunique scenario, where the magnitude as well as the sign of the photo-induced\nchange in conductivity become bias dependent. A theoretical model is developed,\nwhere both the effects are attributed to the 2D electron gas (2DEG) channel\nformed just below the film surface as a result of the transfer of electrons\nfrom certain donor-like-surfacestates, which are likely to be resulting due to\nthe adsorption of certain groups/adatoms on the film surface. In the model, the\nphoto-EMF effect is explained in terms of a spatially inhomogeneous\ndistribution of these groups/adatoms over the surface resulting in a lateral\nnon-uniformity in the depth distribution of the potential profile confining the\n2DEG. Existence of such an inhomogeneity in the distribution of surface\npotential has indeed been experimentally found for these layers."
    },
    {
        "anchor": "Theoretical X-Ray Absorption Debye-Waller Factors: An approach is presented for theoretical calculations of the Debye-Waller\nfactors in x-ray absorption spectra. These factors are represented in terms of\nthe cumulant expansion up to third order. They account respectively for the net\nthermal expansion $\\sigma^{(1)}(T)$, the mean-square relative displacements\n$\\sigma^2(T)$, and the asymmetry of the pair distribution function\n$\\sigma^{(3)}(T)$. Similarly, we obtain Debye-Waller factors for x-ray and\nneutron scattering in terms of the mean-square vibrational amplitudes $u^2(T)$.\nOur method is based on density functional theory calculations of the dynamical\nmatrix, together with an efficient Lanczos algorithm for projected phonon\nspectra within the quasi-harmonic approximation. Due to anharmonicity in the\ninteratomic forces, the results are highly sensitive to variations in the\nequilibrium lattice constants, and hence to the choice of exchange-correlation\npotential. In order to treat this sensitivity, we introduce two prescriptions:\none based on the local density approximation, and a second based on a modified\ngeneralized gradient approximation. Illustrative results for the leading\ncumulants are presented for several materials and compared with experiment and\nwith correlated Einstein and Debye models. We also obtain Born-von Karman\nparameters and corrections due to perpendicular vibrations.",
        "positive": "Multi-Dot Floating-Gates for Nonvolatile Semiconductor Memories - Their\n  Ion Beam Synthesis and Morphology: Scalability and performance of current flash memories can be improved\nsubstantially by replacing the floating poly-Si gate by a layer of Si dots.\nThis multi-dot layer can be fabricated CMOS-compatibly in very thin gate oxide\nby ion beam synthesis (IBS). Here, we present both experimental and theoretical\nstudies on IBS of multi-dot layers consisting of Si nanocrystals (NCs). The NCs\nare produced by ultra low energy Si ion implantation, which causes a high Si\nsupersaturation in the shallow implantation region. During post-implantation\nannealing, this supersaturation leads to phase separation of the excess Si from\nthe SiO2. Till now, the study of this phase separation process suffered from\nthe weak Z contrast between Si and SiO2 in Transmission Electron Microscopy\n(TEM). Here, this imaging problem is resolved by mapping Si plasmon losses with\na Scanning Transmission Electron Microscopy equipped with a parallel Electron\nEnergy Loss Spectroscopy system (PEELS-STEM). Additionally, kinetic lattice\nMonte Carlo simulations of Si phase separation have been performed and compared\nwith the experimental Si plasmon maps. It has been predicted theoretically that\nthe morphology of the multi-dot Si floating-gate changes with increasing ion\nfluence from isolated, spherical NCs to percolated spinodal Si pattern. These\npatterns agree remarkably with PEELS-STEM images. However, the predicted\nfluence for spinodal patterns is lower than the experimental one. Because\noxidants of the ambient atmosphere penetrate into the as-implanted SiO2, a\nsubstantial fraction of the implanted Si might be lost due to oxidation."
    },
    {
        "anchor": "Two-dimensional boron on Pb (110) surface: We simulate boron on Pb(110) surface by using ab initio evolutionary\nmethodology. Interestingly, the two-dimensional (2D) Dirac Pmmn boron can be\nformed because of good lattice matching. Unexpectedly, by increasing the\nthickness of 2D boron, a three-bonded graphene-like structure (P2_1/c boron)\nwas revealed to possess double anisotropic Dirac cones. It is 20 meV/atom lower\nin energy than the Pmmn structure, indicating the most stable 2D boron with\nparticular Dirac cones. The puckered structure of P2_1/c boron results in the\npeculiar Dirac cones, as well as substantial mechanical anisotropy. The\ncalculated Young's modulus is 320 GPa.nm along zigzag direction, which is\ncomparable with graphene.",
        "positive": "Large magnetocrystalline anisotropy in tetragonally distorted Heuslers:\n  a systematic study: With a view to the design of hard magnets without rare earths we explore the\npossibility of large magnetocrystalline anisotropy energies in Heusler\ncompounds that are unstable with respect to a tetragonal distortion. We\nconsider the Heusler compounds Fe$_2$YZ with Y = (Ni, Co, Pt), and Co$_2$YZ\nwith Y = (Ni, Fe, Pt) where, in both cases, Z = (Al, Ga, Ge, In, Sn). We find\nthat for the Co$_2$NiZ, Co$_2$PtZ, and Fe$_2$PtZ families the cubic phase is\nalways, at $T=0$, unstable with respect to a tetragonal distortion, while, in\ncontrast, for the Fe$_2$NiZ and Fe$_2$CoZ families this is the case for only 2\ncompounds -- Fe$_2$CoGe and Fe$_2$CoSn. For all compounds in which a tetragonal\ndistortion occurs we calculate the MAE finding remarkably large values for the\nPt containing Heuslers, but also large values for a number of the other\ncompounds (e.g. Co$_2$NiGa has an MAE of -2.11~MJ/m$^3$). The tendency to a\ntetragonal distortion we find to be strongly correlated with a high density of\nstates at the Fermi level in the cubic phase. As a corollary to this fact we\nobserve that upon doping compounds for which the cubic structure is stable such\nthat the Fermi level enters a region of high DOS, a tetragonal distortion is\ninduced and a correspondingly large value of the MAE is then observed."
    },
    {
        "anchor": "Magnetic resonances of multiferroic TbFe$_3$(BO$_3$)$_4$: Low-energy magnetic excitations of the easy-axis antiferromagnet\nTbFe$_3$(BO$_3$)$_4$ are investigated by far-infrared absorption and reflection\nspectroscopy in high magnetic fields up to 30 T. The observed field dependence\nof the resonance frequencies and the magnetization are reproduced by a\nmean-field spin model for magnetic fields applied both along and perpendicular\nto the easy axis. Based on this model we determined the full set of magnetic\ninteractions, including Fe-Fe and Fe-Tb exchange interactions, single-ion\nanisotropy for Tb ions and $g$-factors, which describe the ground-state spin\ntexture and the low-energy spin excitations of TbFe$_3$(BO$_3$)$_4$. Compared\nto earlier studies we allow a small canting of the nearly Ising-like Tb moments\nto achieve a quantitative agreement with the magnetic susceptibility\nmeasurements. The additional high energy magnetic resonance lines observed,\nbesides the two resonances expected for a two-sublattice antiferromagnet,\nsuggest a more complex six-sublattice magnetic ground state for\nTbFe$_3$(BO$_3$)$_4$.",
        "positive": "Energy of low angle grain boundaries based on continuum dislocation\n  structure: In this paper, we present a continuum model to compute the energy of low\nangle grain boundaries for any given degrees of freedom (arbitrary rotation\naxis, rotation angle and boundary plane orientation) based on a continuum\ndislocation structure. In our continuum model, we minimize the grain boundary\nenergy associated with the dislocation structure subject to the constraint of\nFrank's formula for dislocations with all possible Burgers vectors. This\nconstrained minimization problem is solved by the penalty method by which it is\nturned into an unconstrained minimization problem. The grain boundary\ndislocation structure is approximated by a network of straight dislocations\nthat predicts the energy and dislocation densities of the grain boundaries. The\ngrain boundary energy based on the calculated dislocation structure is able to\nincorporate its anisotropic nature. We use our continuum model to\nsystematically study the energy of $<111>$ low angle grain boundaries in fcc Al\nwith any boundary plane orientation and all six possible Burgers vectors.\nComparisons with results of the atomistic simulations show that our continuum\nmodel is able to give excellent predictions of the energy and dislocation\ndensities of low angle grain boundaries. We also study the energy of low angle\ngrain boundaries in fcc Al with varying rotation axis while the rest degrees of\nfreedom are fixed. With minor modifications, our model can also apply to\ndislocation structures and energy of heterogeneous interfaces."
    },
    {
        "anchor": "Dynamical brittle fractures of nanocrystalline silicon using large-scale\n  electronic structure calculations: A hybrid scheme between large-scale electronic structure calculations is\ndeveloped and applied to nanocrystalline silicon with more than 10$^5$ atoms.\nDynamical fracture processes are simulated under external loads in the [001]\ndirection. We shows that the fracture propagates anisotropically on the (001)\nplane and reconstructed surfaces appear with asymmetric dimers. Step structures\nare formed in larger systems, which is understood as the beginning of a\ncrossover between nanoscale and macroscale samples.",
        "positive": "From a bistable adsorbate to a switchable interface: tetrachloropyrazine\n  on Pt(111): Virtually all organic (opto)electronic devices rely on organic/inorganic\ninterfaces with specific properties. These properties are, in turn,\ninextricably linked to the interface structure. Therefore, a change in\nstructure can introduce a shift in function. If this change is reversible, it\nwould allow constructing a switchable interface. We accomplish this with\ntetrachloropyrazine on Pt(111), which exhibits a double-well potential with a\nchemisorbed and a physisorbed minimum. These minima have significantly\ndifferent adsorption geometries allowing the formation of switchable interface\nstructures. Importantly, these structures facilitate different work function\nchanges and coherent fractions (X-ray standing wave measurements), which are\nideal properties to readout the interface state.\n  We perform surface structure search using a modified version of the SAMPLE\napproach and account for thermodynamic conditions using ab-initio\nthermodynamics. This allows investigating millions of commensurate as well as\nhigher-order commensurate interface structures. We identify three different\nclasses of structures exhibiting different work function changes and coherent\nfractions. Using temperature and pressure as handles we demonstrate the\npossibility of reversible switching between those different classes, creating a\ndynamic interface for potential applications in organic electronics."
    },
    {
        "anchor": "Quasiparticle Corrections to the Electronic Properties of Anion\n  Vacancies at GaAs(110) and InP(110): We propose a new method for calculating optical defect levels and\nthermodynamic charge-transition levels of point defects in semiconductors,\nwhich includes quasiparticle corrections to the Kohn-Sham eigenvalues of\ndensity-functional theory. Its applicability is demonstrated for anion\nvacancies at the (110) surfaces of III-V semiconductors. We find the (+/0)\ncharge-transition level to be 0.49 eV above the surface valence-band maximum\nfor GaAs(110) and 0.82 eV for InP(110). The results show a clear improvement\nover the local-density approximation and agree closely with an experimental\nanalysis.",
        "positive": "CE Screen: an energy-based structure selection method: We have developed a method to improve the doping computation efficiency, this\nmethod is based on first principles calculations and cluster expansion. First\nprinciples codes produce highly accurate total energies and optimized\ngeometries for any given structure. Cluster expansion method constructs a\ncluster expansion using partial first principles results and computes the\nenergies for other structures derived from a parent lattice. Using this method,\nenergies for multiple doping structures can be predicted quickly without series\nof first principles calculations. This method has been packaged into a tool\nnamed as CE Screen and integrated into MatCloud (A high-throughput first\nprinciples calculation platform). This makes the tool simple and easy for all\nthe users."
    },
    {
        "anchor": "Few-layer Tellurium: one-dimensional-like layered elementary\n  semiconductor with striking physical properties: Few-layer Tellurium, an elementary semiconductor, succeeds most of striking\nphysical properties that black phosphorus (BP) offers and could be feasibly\nsynthesized by simple solution-based methods. It is comprised of non-covalently\nbound parallel Te chains, among which covalent-like feature appears. This\nfeature is, we believe, another demonstration of the previously found\ncovalent-like quasi-bonding (CLQB) where wavefunction hybridization does occur.\nThe strength of this inter-chain CLQB is comparable with that of intra-chain\ncovalent bonding, leading to closed stability of several Te allotropes. It also\nintroduces a tunable bandgap varying from nearly direct 0.31 eV (bulk) to\nindirect 1.17 eV (2L) and four (two) complex, highly anisotropic and\nlayer-dependent hole (electron) pockets in the first Brillouin zone. It also\nexhibits an extraordinarily high hole mobility (~10$^5$ cm$^2$/Vs) and strong\noptical absorption along the non-covalently bound direction, nearly isotropic\nand layer-dependent optical properties, large ideal strength over 20%, better\nenvironmental stability than BP and unusual crossover of force constants for\ninterlayer shear and breathing modes. All these results manifest that the\nfew-layer Te is an extraordinary-high-mobility, high optical absorption,\nintrinsic-anisotropy, low-cost-fabrication, tunable bandgap, better\nenvironmental stability and nearly direct bandgap semiconductor. This\n\"one-dimension-like\" few-layer Te, together with other geometrically similar\nlayered materials, may promote the emergence of a new family of layered\nmaterials.",
        "positive": "The Jeff=1/2 antiferromagnet Sr2IrO4: A golden avenue toward new physics\n  and functions: Iridates have been providing a fertile ground for studying emergent phases of\nmatter that arise from delicate interplay of various fundamental interactions\nwith approximate energy scale. Among these highly focused quantum materials,\nperovskite Sr2IrO4 belonging to the Ruddlesden-Popper series stands out and has\nbeen intensively addressed in the last decade, since it hosts a novel Jeff =\n1/2 state which is a profound manifestation of strong spin-orbit coupling.\nMoreover, the Jeff = 1/2 state represents a rare example of iridates that has\nbeen better understood both theoretically and experimentally. In this progress\nreport, we take Sr2IrO4 as an example to overview the recent advances of the\nJeff = 1/2 state in two aspects: materials fundamentals and functionality\npotentials. In the fundamentals part, we first illustrate basic issues for the\nlayered canted antiferromagnetic order of the Jeff = 1/2 magnetic moments in\nSr2IrO4, and then review the progress of the antiferromagnetic order modulation\nthrough diverse routes. Subsequently, for the functionality potentials,\nfascinating properties such as atomic-scale giant magnetoresistance,\nanisotropic magnetoresistance, and nonvolatile memory, will be addressed. This\nreport will be concluded with our prospected remarks and outlooks."
    },
    {
        "anchor": "Accurate melting point prediction through autonomous physics-informed\n  learning: We present an algorithm for computing melting points by autonomously learning\nfrom coexistence simulations in the NPT ensemble. Given the interatomic\ninteraction model, the method makes decisions regarding the number of atoms and\ntemperature at which to conduct simulations, and based on the collected data\npredicts the melting point along with the uncertainty, which can be\nsystematically improved with more data. We demonstrate how incorporating\nphysical models of the solid-liquid coexistence evolution enhances the\nalgorithm's accuracy and enables optimal decision-making to effectively reduce\npredictive uncertainty. To validate our approach, we compare the results of 20\nmelting point calculations from the literature to the results of our\ncalculations, all conducted with same interatomic potentials. Remarkably, we\nobserve significant deviations in about one-third of the cases, underscoring\nthe need for accurate and reliable algorithms for materials property\ncalculations.",
        "positive": "Simple mechanism for a positive exchange bias: We argue that the interface coupling, responsible for the positive exchange\nbias (HE) observed in ferromagnetic/compensated antiferromagnetic (FM/AF)\nbilayers, favors an antiferromagnetic alignment. At low cooling field this\ncoupling polarizes the AF spins close to the interface, which spin\nconfiguration persists after the sample is cooled below the Neel temperature.\nThis pins the FM spins as in Bean's model and gives rise to a negative HE. When\nthe cooling field increases, it eventually dominates and polarizes the AF spins\nin an opposite direction to the low field one. This results in a positive HE.\nThe size of HE and the crossover cooling field are estimated. We explain why HE\nis mostly positive for an AF single crystal, and discuss the role of interface\nroughness on the magnitude of HE, and the quantum aspect of the interface\ncoupling."
    },
    {
        "anchor": "Electronic, optical and thermal properties of highly stretchable 2D\n  carbon Ene-yne graphyne: Recently, a new carbon-based two-dimensional (2D) material, so called \"carbon\nEne-yne\" (CEY), was successfully synthesized. In this work, we examine\nelectronic, optical and thermal properties of this novel material. We studied\nthe stretchability of CEY via density functional theory (DFT) calculations.\nUsing the PBE and HSE06 functionals, as well as the G$_0$W$_0$ method and the\nBethe-Salpeter equation, we systematically explored electronic and optical\nproperties of 2D CEY. In particular, we investigated the change of band-gap and\noptical properties under uniaxial and biaxial strain. Ab-initio molecular\ndynamics simulations confirm that CEY is stable at temperatures as high as 1500\nK. Using non-equilibrium molecular dynamics simulations, the thermal\nconductivity of CEY was predicted to be anisotropic and three orders of\nmagnitude smaller than that of graphene. We found that in the visible range,\nthe optical conductivity under high strain levels is larger than that of\ngraphene. This enhancement in optical conductivity may allow CEY to be used in\nphotovoltaic cells. Moreover, CEY shows anisotropic optical responses for x-\nand y- polarized light, which may be suitable as an optical linear polarizer.\nThe comprehensive insight provided by the present investigation should serve as\na guide for possible applications of CEY in nanodevices.",
        "positive": "Tuning the band gap of PbCrO4 through high-pressure: Evidence of\n  wide-to-narrow semiconductor transitions: The electronic transport properties and optical properties of lead(II)\nchromate (PbCrO4) have been studied at high pressure by means of resistivity,\nHall-effect, and optical-absorption measurements. Band-structure\nfirst-principle calculations have been also performed. We found that the\nlow-pressure phase is a direct band-gap semiconductor (Eg = 2.3 eV) that shows\na high resistivity. At 3.5 GPa, associated to a structural phase transition, a\nband-gap collapse takes place, becoming Eg = 1.8 eV. At the same pressure the\nresistivity suddenly decreases due to an increase of the carrier concentration.\nIn the HP phase, PbCrO4 behaves as an n-type semiconductor, with a donor level\nprobably associated to the formation of oxygen vacancies. At 15 GPa a second\nphase transition occurs to a phase with Eg = 1.2 eV. In this phase, the\nresistivity increases as pressure does probably due to the self-compensation of\ndonor levels and the augmentation of the scattering of electrons with ionized\nimpurities. In the three phases the band gap red shifts under compression. At\n20 GPa, Eg reaches a value of 0.8 eV, behaving PbCrO4 as a narrow-gap\nsemiconductor."
    },
    {
        "anchor": "Magnetoentropic signatures of skyrmionic phase behavior in FeGe: We demonstrate that magnetocaloric measurements can rapidly reveal details of\nthe phase diagrams of high-temperature skyrmion hosts, concurrently yielding\nquantitative latent heats of the field-driven magnetic phase transitions. Our\napproach addresses an outstanding issue in the phase diagram of the skyrmion\nhost FeGe by showing that dc magnetic anomalies can be explained in terms of\nentropic signatures consistent with a phase diagram containing a single pocket\nof skyrmionic order and a Brazovskii transition.",
        "positive": "A fusion of the LAPW and the LMTO methods: the augmented plane wave plus\n  muffin-tin orbital (PMT) method: We present a new full-potential method to solve the one-body problem, for\nexample, in the local density approximation. The method uses the augmented\nplane waves (APWs) and the generalized muffin-tin orbitals (MTOs) together as\nbasis sets to represent the eigenfunctions. Since the MTOs can efficiently\ndescribe localized orbitals, e.g, transition metal 3$d$ orbitals, the total\nenergy convergence with basis size is drastically improved in comparison with\nthe linearized APW method. Required parameters to specify MTOs are given by\natomic calculations in advance. Thus the robustness, reliability, easy-of-use,\nand efficiency at this method can be superior to the linearized APW and MTO\nmethods. We show how it works in typical examples, Cu, Fe, Li, SrTiO$_3$, and\nGaAs."
    },
    {
        "anchor": "Modeling Composites of Multi-Walled Carbon Nanotubes in Polycarbonate: High strain rate experiments performed on multi-walled carbon nanotubes and\npolycarbonate composites (MWCNT-PC) have exhibited enhanced impact resistance\nunder a dynamic strain rate of nearly 2500/s with composition of only 0.5 to\n2.0 percent of Multi walled carbon nanotubes(MWCNTs) in pure polycarbonate(PC).\nSimilarly, hardness and elastic modulus under static loads resulted in\nsignificant increase depending upon the composition of MWCNTs in PC.The present\nwork aims to analyze these results by correlating the data to fit expressions\nin generalizing the behavior of MWCNTs composition for MWCNT-PC composites\nunder both static and impact loads. As a result we found that an optimum\ncomposition of 2.1 percent of MWCNTs exhibits maximum stress resistance within\nelastic range under strain rates of nearly 2500/s for MWCNT-PC composites.The\nresults are critically dependent on the composition of MWCNTs and significantly\ndeteriorate below and above a threshold composition. A simple model based on\nLennard-Jones atom-atom based potential is formulated to compute static\nproperties of pure as well as composites of PC.",
        "positive": "Low-temperature synthesis and electrocatalytic application of large-area\n  PtTe2 thin films: The synthesis of transition metal dichalcogenides (TMDs) has been a primary\nfocus for 2D nanomaterial research over the last 10 years, however, only a\nsmall fraction of this research has been concentrated on transition metal\nditellurides. In particular, nanoscale platinum ditelluride (PtTe2) has rarely\nbeen investigated, despite its potential applications in catalysis, photonics\nand spintronics. Of the reports published, the majority examine\nmechanically-exfoliated flakes from chemical vapor transport (CVT) grown\ncrystals. While this production method is ideal for fundamental studies, it is\nvery resource intensive therefore rendering this process unsuitable for large\nscale applications. In this report, the synthesis of thin films of PtTe2\nthrough the reaction of solid-phase precursor films is described. This offers a\nproduction method for large-area, thickness-controlled PtTe2, suitable for a\nrange of applications. These polycrystalline PtTe2 films were grown at\ntemperatures as low as 450 degC, significantly below the typical temperatures\nused in the CVT synthesis methods. To investigate their potential\napplicability, these films were examined as electrocatalysts for the hydrogen\nevolution reaction (HER) and oxygen reduction reaction (ORR). The films showed\npromising catalytic behavior, however, the PtTe2 was found to undergo chemical\ntransformation to a substoichiometric chalcogenide compound under ORR\nconditions. This study shows while PtTe2 is stable and highly useful for HER,\nthis property does not apply to ORR, which undergoes a fundamentally different\nmechanism. This study broadens our knowledge of the electrocatalysis of TMDs."
    },
    {
        "anchor": "Modulated Martensite: Why it forms and why it deforms easily: Diffusionless phase transitions are at the core of the multifunctionality of\n(magnetic) shape memory alloys, ferroelectrics and multiferroics. Giant strain\neffects under external fields are obtained in low symmetric modulated\nmartensitic phases. We outline the origin of modulated phases, their connection\nwith tetragonal martensite and consequences for their functional properties by\nanalysing the martensitic microstructure of epitaxial Ni-Mn-Ga films from the\natomic to macroscale. Geometrical constraints at an austenite-martensite phase\nboundary act down to the atomic scale. Hence a martensitic microstructure of\nnanotwinned tetragonal martensite can form. Coarsening of twin variants can\nreduce twin boundary energy, a process we could follow from the atomic to the\nmillimetre scale. Coarsening is a fractal process, proceeding in discrete steps\nby doubling twin periodicity. The collective defect energy results in a\nsubstantial hysteresis, which allows retaining modulated martensite as a\nmetastable phase at room temperature. In this metastable state elastic energy\nis released by the formation of a 'twins within twins' microstructure which can\nbe observed from the nanometre to millimetre scale. This hierarchical twinning\nresults in mesoscopic twin boundaries which are diffuse, in contrast to the\ncommon atomically sharp twin boundaries of tetragonal martensite. We suggest\nthat observed extraordinarily high mobility of such mesoscopic twin boundaries\noriginates from their diffuse nature which renders pinning by atomistic point\ndefects ineffective.",
        "positive": "Orbital moment of a single Co atom on a Pt(111) surface - a view from\n  correlated band theory: The orbital magnetic moment of a Co adatom on a Pt(111) surface is calculated\nin good agreement with experimental data making use of the LSDA+U method. It is\nshown that both electron correlation induced orbital polarization and\nstructural relaxation play essential roles in orbital moment formation. The\nmicroscopic origins of the orbital moment enhancement are discussed."
    },
    {
        "anchor": "Comparative study of adatom manipulation on several fcc metal surfaces: For a set of fcc metals our total energy calculations, based on many body\npotentials, show that activation barriers for lateral manipulation of an adatom\nat a step edge depend on the tip/substrate composition. Of the six homogeneous\nsystems studied, manipulation on stepped Ag(111) showed the lowest energy\nbarrier for adatom hopping towards the tip, although the relative probability\nfor this process was largest on Cu(111). For a representative Cu/Pt\nheterogeneous system we find lateral manipulation of a Pt adatom along a step\non Pt(111) by a Cu(100) tip to be energetically much less favourable than the\nreverse case of a Cu adatom manipulated by a Pt(100) tip. In the case of\nvertical manipulation, atomic relaxations of the tip and its neighbouring atoms\nare found to be prominent and tip induced changes in the bonding of the adatom\nto its low coordinated surroundings help explain the relative ease with which\nan adatom next to a step edge or a kink site, may be pulled, as compared to\nthat on a flat surface.",
        "positive": "High Pressure and Temperature Neural Network Reactive Force Field for\n  Energetic Materials: Reactive force fields for molecular dynamics have enabled a wide range of\nstudies in numerous material classes. These force fields are computationally\ninexpensive as compared to electronic structure calculations and allow for\nsimulations of millions of atoms. However, the accuracy of traditional force\nfields is limited by their functional forms, preventing continual refinement\nand improvement. Therefore, we develop a neural network based reactive\ninteratomic potential for the prediction of the mechanical, thermal, and\nchemical response of energetic materials at extreme conditions for energetic\nmaterials. The training set is expanded in an automatic iterative approach and\nconsists of various CHNO materials and their reactions under ambient and under\nshock loading conditions. This new potential shows improved accuracy over the\ncurrent state of the art force fields for a wide range of properties such as\ndetonation performance, decomposition product formation, and vibrational\nspectra under ambient and shock loading conditions."
    },
    {
        "anchor": "Comprehensive Study of Lithium Adsorptionand Diffusion on Janus Mo/WXY\n  (X, Y= S,Se, Te) using First Principles and MachineLearning Approaches: The structural asymmetry of two-dimensional (2D) Janus transition metal\ndichalcogenides (TMDs) produces internal dipole moments that result in\ninteresting electronic properties. These properties differ from the regular\n(symmetric) TMD structures that the Janus structures are derived from. In this\nstudy, we, at first, examine adsorption and diffusion of a single Li atom on\nregular MX2and Janus MXY (M = Mo, W; XY =S, Se, Te) TMD structures at various\nconcentrations using first principles calculations within density functional\ntheory. To gain more physical insight and prepare for future investigations of\nregular TMD and Janus materials, we applied a supervised machine learning (ML)\nmodel that uses cluster-wise linear regression to predict the adsorption\nenergies of Li on top of 2D TMDs. We developed a universal representation with\nfew descriptors that take into account the intrinsic dipole moment and the\nelectronic structure of regular and Janus 2D layers, the side where the\nadsorption takes place and the concentration dependence of adatom doping. This\nrepresentation can easily be generalized to be used for other impurities and 2D\nlayer combinations, including alloys as well. At last, we focus on analyzing\nthese structures as possible anodes in battery applications. We conducted Li\ndiffusion, open-circuit-voltage and storage capacity simulations. We report\nthat Lithium atoms are found to easily migrate between transition metal (Mo, W)\ntop sites for each considered case, and in these respects many of the examined\nJanus materials are comparable or superior to graphene and to regular TMDs. The\nresults imply that theexamined Janus structures should perform well as\nelectrodes in Li-ion batteries.",
        "positive": "Magnetic order of Mn-doped ZnO: A Monte Carlo simulation of Carriers\n  Concentration's effect: Recently, diluted Magnetic Semiconductors (DMS) doped with a small\nconcentration of magnetic impurities, especially DMS doped with transition\nmetal, inducing ferromagnetic DMSs have attracted a great interest. Using the\nMonte Carlo method within the Ising model,we study the magnetic properties of\ndoped Mn ions in semi-conductor for different carrier's concentration. For the\ncase of Zn1-xMnxO, the results of our calculations show the effect of carriers\nin understanding the existence and the control of the magnetic order. We give\nalso the exact values of carriers' concentration that should be adopted or\navoided in order to get ferromagnetic phase with high Curie temperature."
    },
    {
        "anchor": "Coexistence of Dirac fermion and charge density wave in square-net-based\n  semimetal LaAuSb2: We report a comprehensive study of magnetotransport properties,\nangle-resolved photoemission spectroscopy (ARPES), and density functional\ntheory (DFT) calculations on self-flux grown LaAuSb$_2$ single crystals.\nResistivity and Hall measurements reveal a charge density wave (CDW) transition\nat 77 K. MR and de Haas-Van Alphen (dHvA) measurements indicate that the\ntransport properties of LaAuSb$_2$ are dominated by Dirac fermions that arise\nfrom Sb square nets. ARPES measurements and DFT calculations reveal an\nelectronic structure with a common feature of the square-net-based topological\nsemimetals, which is in good agreement with the magnetotransport properties.\nOur results indicate the coexistence of CDW and Dirac fermion in LaAuSb$_2$,\nboth of which are linked to the bands arising from the Sb-square net,\nsuggesting that the square net could serve as a structural motif to explore\nvarious electronic orders.",
        "positive": "Optimized Non-Orthogonal Localized Orbitals for Electronic Structure\n  Calculations: Improved Linear Scaling Quantum Monte Carlo: We derive an automatic procedure for generating a set of highly localized,\nnon-orthogonal orbitals for linear scaling quantum Monte Carlo calculations. We\ndemonstrate the advantage of these orbitals in calculations of the total energy\nof both semiconducting and metallic systems by studying bulk silicon and the\nhomogeneous electron gas. For silicon, the improved localization of these\norbitals reduces the computational time by a factor five and the memory by a\nfactor of six compared to localized, orthogonal orbitals. For jellium, we\ndemonstrate that the total energy is converged for orbitals truncated within\nspheres with radii 7-8 $r_s$, opening the possibility of linear scaling QMC\ncalculations for realistic metallic systems."
    },
    {
        "anchor": "Theoretical analysis of magnetic coupling in sandwich clusters\n  V_n(C_6H_6)_{n+1}: The mechanism of ferromagnetism stability in sandwich clusters\nV$_n$(C$_6$H$_6$)$_{n+1}$ has been studied by first-principles calculation and\nmodel analysis. It is found that each of the three types of bonds between V and\nbenzene (Bz) plays different roles. V 3d$_{z^2}$ orbital, extending along the\nmolecular axis, is weakly hybridized with Bz's HOMO-1 orbital to form the\n$\\sigma$-bond. It is quite localized and singly occupied, which contributes\n1$\\mu_B$ to the magnetic moment but little to the magnetic coupling of\nneighboring V magnetic moments. The in-plane d$_{x^2-y^2}$, d$_{xy}$ orbitals\nare hybridized with the LUMO of Bz and constitute the $\\delta$-bond. This\nhybridization is medium and crucial to the magnetic coupling though the\n$\\delta$ states have no net contribution to the total magnetic moment.\nd$_{xz}$, d$_{yz}$ and HOMO of Bz form a quite strong $\\pi$-bond to hold the\nmolecular structure but they are inactive in magnetism because their energy\nlevels are far away from the Fermi level. Based on the results of\nfirst-principles calculation, we point out that the ferromagnetism stability is\nclosely related with the mechanism proposed by Kanamori and Terakura [J.\nKanamori and K. Terakura, J. Phys. Soc. Jpn. 70, 1433 (2001)]. However, the\npresence of edge Bz's in the cluster introduces an important modification. A\nsimple model is constructed to explain the essence of the physical picture.",
        "positive": "Unraveling the nature of thermally induced spin reorientation in\n  NdFe1-xCrxO3: Understanding spin control mechanisms is an important part of condensed\nmatter physics and the theoretical basis for designing spintronic devices. In\nthis letter, based on four-sublattices molecular field theory, we propose that\nthe underlying NdFe1-xCrxO3 magnetic mechanism is driven by spin reorientation\nsensitive to temperature. The actual coupling angular momentum, angle between\nthe Nd3+ and Cr3+/Fe3+ moments at the given temperature is realized via the\nNd3+ magnetic moment projection onto the Cr3+/Fe3+ plane. As the temperature\nincreases, the angle between the moment of Nd3+ and the moment of Cr3+/Fe3+\ndecreases monotonically. In this work, the magnetic mechanism of NdFe1-xCrxO3\n(x=0.1, 0.9), the close relationship between A/B angle and temperature are\npresented, which laid a theoretical foundation for the design of new\nmultifunctional magnetic materials."
    },
    {
        "anchor": "Sr-induced dipole scatter in BST: Insights from MD simulations using a\n  transferable bond valence-based interatomic potential: In order to design next-generation ferroelectrics, a microscopic\nunderstanding of their macroscopic properties is critical. One means to\nachieving an atomistic description of ferroelectric and dielectric phenomena is\nclassical molecular dynamics simulations. Previously, we have shown that\ninteratomic potentials based on the bond valence molecular dynamics (BVMD)\nmethod can be used to study structural phase transitions, ferroelectric domain\nnucleation, and domain wall migration in several perovskite oxides and\nfixed-composition binary and ternary alloys. Most modern devices, however, use\nvariable-composition perovskite oxide alloys such as Ba$_x$Sr$_{1-x}$TiO$_3$\n(BST). In this paper, we extend our bond valence approach to BST solid\nsolutions and, in so doing, show that the potential parameters for each element\nare transferable between materials with different $x$. Using this potential, we\nperform BVMD simulations investigating the temperature and composition\ndependence of the lattice constants, Ti displacements, and ferroelectric\npolarization of BST and find that our predictions match experiments and\nfirst-principles theory. Additionally, based on a detailed analysis of local\ndipole distributions, we demonstrate that substitution of Sr for Ba scrambles\ndipoles, reduces global polarization, and enhances the order-disorder character\nof the ferroelectric-paraelectric phase transition.",
        "positive": "The nature of iron-oxygen vacancy defect centers in PbTiO3: The iron(III) center in ferroelectric PbTiO3 together with an oxygen vacancy\nforms a charged defect associate, oriented along the crystallographic c-axis.\nIts microscopic structure has been analyzed in detail comparing results from a\nsemi-empirical Newman superposition model analysis based on finestructure data\nand from calculations using density functional theory.\n  Both methods give evidence for a substitution of Fe3+ for Ti4+ as an acceptor\ncenter. The position of the iron ion in the ferroelectric phase is found to be\nsimilar to the B-site in the paraelectric phase. Partial charge compensation is\nlocally provided by a directly coordinated oxygen vacancy.\n  Using high-resolution synchrotron powder diffraction, it was verified that\nlead titanate remains tetragonal down to 12 K, exhibiting a c/a-ratio of\n1.0721."
    },
    {
        "anchor": "Ultrafast dynamics of a magnetic antivortex - Micromagnetic simulations: The antivortex is a fundamental magnetization structure which is the\ntopological counterpart of the well-known magnetic vortex. We study here the\nultrafast dynamic behavior of an isolated antivortex in a patterned Permalloy\nthin-film element. Using micromagnetic simulations we predict that the\nantivortex response to an ultrashort external field pulse is characterized by\nthe production of a new antivortex as well as of a temporary vortex, followed\nby an annihilation process. These processes are complementary to the recently\nreported response of a vortex and, like for the vortex, lead to the reversal of\nthe orientation of the antivortex core region. In addition to its fundamental\ninterest, this dynamic magnetization process could be used for the generation\nand propagation of spin waves for novel logical circuits.",
        "positive": "Ca-dimers, solvent layering, and dominant electrochemically active\n  species in Ca(BH$_4$)$_2$ in THF: Divalent ions, such as Mg, Ca, and Zn, are being considered as competitive,\nsafe, and earth-abundant alternatives to Li-ion electrochemistry. However, the\nchallenge remains to match electrode and electrolyte materials that stably\ncycle with these new formulations, based primarily on controlling interfacial\nphenomena. We explore the formation of electroactive species in the electrolyte\nCa(BH$_4$)$_2$ in THF through molecular dynamics simulation. Free-energy\nanalysis indicates that this electrolyte has a majority population of neutral\nCa dimers and monomers, albeit with diverse molecular conformations as revealed\nby unsupervised learning techniques, but with an order of magnitude lower\nconcentration of possibly electroactive charged species, such as the\nmonocation, CaBH$_4^+$ , which we show is produced via disproportionation of\nneutral Ca(BH$_4$)$_2$ complexes. Dense layering of THF molecules within 1 nm\nof the electrode surface (modeled here using graphite) hinders the approach of\nreducible species to within 0.6 nm and instead enhances the local concetration\nof species in a narrow intermediate-density layer from 0.7-0.9 nm. A dramatic\nincrease in the monocation population in this intermediate layer is induced at\nnegative bias, supplied by local dimer disproportionation. We see no evidence\nto support any functional role of fully-solvated Ca$^{2+}$ in the\nelectrochemical activity of this electrolyte. The consequences for performance\nand alternative formulations are discussed in light of this molecular-scale\ninsight."
    },
    {
        "anchor": "The electrostatic interaction of an external charged system with a metal\n  surface: a simplified density functional theory approach: As a first step to meet the challenge to calculate the electronic structure\nand total energy of charged states of atoms and molecules adsorbed on\nultrathin-insulating films supported by a metallic substrate using density\nfunctional theory (DFT), we have developed a simplified new DFT scheme that\nonly describes the electrostatic interaction of an external charged system with\na metal surface. This purely electrostatic interaction is obtained from the\nassumption that the electron densities of the two fragments (charged system and\nmetal surface) are non-overlapping and neglecting non-local exchange\ncorrelation effects such as the van der Waals interactions between the two\nfragments. In addition, the response of the metal surface to the electrostatic\npotential from the charged system is treated to linear order, whereas the\ncharged system is treated fully within DFT. In particular, we consider the\nclassical perfect conductor (PC) model for the metal response, although our\nformalism is not limited to this approximation. The successful computational\nimplementation of this new methodology and the PC model is exemplified by the\ncase of a Na$^{+}$ cation outside a metal surface.",
        "positive": "Porous amorphous nitinol synthesized by argon injection: a molecular\n  dynamics study: Porous crystalline nitinol is widely applied in various fields of science and\ntechnology due to the unique combination of physical and mechanical properties\nas well as biocompatibility. Porous amorphous nitinol is characterized by\nimproved mechanical properties compared to its crystalline analogues. Moreover,\nthis material is more promising from the point of view of fundamental study and\npractical application. The production of porous amorphous nitinol is a\ndifficult task requiring rapid cooling protocol and optimal conditions to form\na stable porous structure. In the present work, based on the results of\nmolecular dynamics simulations, we show that porous nitinol with the amorphous\nmatrix can be obtained by injection of argon into a liquid melt followed by\nrapid cooling of the resulting mixture. We find that the porosity of the system\nincreases exponentially with increasing fraction of injected argon. It has been\nestablished that the system should contain about $\\sim18$--$23$\\% argon for\nobtain an open porous structure, while the system is destroyed by overheated\ninert gas when the argon fraction is more than $\\sim23$\\%. It is shown that the\nmethod of argon injection makes it possible to obtain a highly porous system\nwith the porosity $\\sim70$\\% consisting the spongy porous structure similar to\naerogels and metallic foams."
    },
    {
        "anchor": "Towards Quantitative Evaluation of Crystal Structure Prediction\n  Performance: Crystal structure prediction (CSP) is now increasingly used in the discovery\nof novel materials with applications in diverse industries. However, despite\ndecades of developments, the problem is far from being solved. With the\nprogress of deep learning, search algorithms, and surrogate energy models,\nthere is a great opportunity for breakthroughs in this area. However, the\nevaluation of CSP algorithms primarily relies on manual structural and\nformation energy comparisons. The lack of a set of well-defined quantitative\nperformance metrics for CSP algorithms make it difficult to evaluate the status\nof the field and identify the strengths and weaknesses of different CSP\nalgorithms. Here, we analyze the quality evaluation issue in CSP and propose a\nset of quantitative structure similarity metrics, which when combined can be\nused to automatically determine the quality of the predicted crystal structures\ncompared to the ground truths. Our CSP performance metrics can be then utilized\nto evaluate the large set of existing and emerging CSP algorithms, thereby\nalleviating the burden of manual inspection on a case-by-case basis. The\nrelated open-source code can be accessed freely at\nhttps://github.com/usccolumbia/CSPBenchMetrics",
        "positive": "Local ultra-densification of single-walled carbon nanotube films:\n  modeling and experiment: Fabrication of nanostructured metasurfaces poses a significant technological\nand fundamental challenge. Despite developing novel systems that support\nreversible elongation and distortion, their nanoscale patterning and control of\noptical properties remain an open problem. Herein we report the atomic force\nmicroscope lithography (AFML) application for nanoscale patterning of\nsingle-walled carbon nanotube films and the associated reflection coefficient\ntuning. We present models of bundling reorganization, formed-pattern stability,\nand energy distribution describing mechanical behavior with mesoscopic distinct\nelement method (MDEM). All observed and calculated phenomena support each other\nand present a platform for developing AFML patterned optical devices using\nmeshy nanostructured matter."
    },
    {
        "anchor": "Temperature Dependence of the Energy Levels of Methylammonium Lead\n  Iodide Perovskite from First Principles: Environmental effects and intrinsic energy-loss processes lead to\nfluctuations in the operational temperature of solar cells, which can\nprofoundly influence their power conversion efficiency. Here we determine from\nfirst principles the effects of temperature on the band gap and band edges of\nthe hybrid pervoskite CH$_3$NH$_3$PbI$_3$ by accounting for electron-phonon\ncoupling and thermal expansion. From $290$ to $380$ K, the computed band gap\nchange of $40$ meV coincides with the experimental change of $30$-$40$ meV. The\ncalculation of electron-phonon coupling in CH$_3$NH$_3$PbI$_3$ is particularly\nintricate, as the commonly used Allen-Heine-Cardona theory overestimates the\nband gap change with temperature, and excellent agreement with experiment is\nonly obtained when including high-order terms in the electron-phonon\ninteraction. We also find that spin-orbit coupling enhances the electron-phonon\ncoupling strength, but that the inclusion of nonlocal correlations using hybrid\nfunctionals has little effect. We reach similar conclusions in the metal-halide\nperovskite CsPbI$_3$. Our results unambiguously confirm for the first time the\nimportance of high-order terms in the electron-phonon coupling by direct\ncomparison with experiment.",
        "positive": "Universal Phase Diagram for High-Piezoelectric Perovskite Systems: Strong piezoelectricity in the perovskite-type PbZr(1-x)TixO3 (PZT) and\nPb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) systems is generally associated with the\nexistence of a morphotropic phase boundary (MPB) separating regions with\nrhombohedral and tetragonal symmetry. An x-ray study of PZN-9%PT has revealed\nthe presence of a new orthorhombic phase at the MPB, and a near-vertical\nboundary between the rhombohedral and orthorhombic phases, similar to that\nfound for PZT between the rhombohedral and monoclinic phases. We discuss the\nresults in the light of a recent theoretical paper by Vanderbilt and Cohen,\nwhich attributes these low-symmetry phases to the high anharmonicity in these\noxide systems."
    },
    {
        "anchor": "Comment on 'A new nanoscale metastable iron phase in carbon steels': We show that the selected area diffraction patterns presented in a recent\npaper (T. Liu et al. Sci. Rep. 2015 5, 15331) do not prove the existence of a\nnew hexagonal phase in martensitic steels. They can be actually simulated by\ntwin effects.",
        "positive": "Middle-obstacle approach of mapping phase-field model unto its sharp\n  interface counterpart: A new diffuse interface model has been proposed in this study for simulating\nbinary alloy solidification under universal cooling conditions, involving both\nequilibrium and non-equilibrium solute partitioning. Starting from the\nGibbs-Thomson equation, which is the classical theory that describes the\ndynamics of a sharp interface, the phase-field equation is derived using a\ntraveling wave solution that represents a diffuse interface. To tackle the\nspurious effects caused by the variation of liquid concentration within the\ndiffuse interface with artificial width, a middle obstacle is introduced to\nsharpen the diffuse interface and an invariant liquid concentration can be\nfound for determining a constant undercooling in the interface normal\ndirection. For slow solidification under equilibrium conditions, the\nconvergence performance of the dendrite tip shows superior invulnerability to\nthe width effect of the diffuse interface. For rapid solidification under\nnon-equilibrium conditions, the output partition coefficients obtained from the\nsteady-state concentration profiles agree with the input velocity-dependent\nfunction. The proposed model is promising to be an indispensable tool for the\ndevelopment of advanced alloy materials through the microstructure control of\nsolidification under a wide range of cooling conditions."
    },
    {
        "anchor": "Negative Magnetoresistance in (In,Mn)As: The magnetotransport properties of an In0.95Mn0.05As thin film grown by\nmetal-organic vapor phase epitaxy were measured. Resistivity was measured over\nthe temperature range of 5 to 300 K. The resistivity decreased with increasing\ntemperature from 90 ohm-cm to 0.05 ohm-cm. The field dependence of the low\ntemperature magnetoresistance was measured. A negative magnetoresistance was\nobserved below 17 K with a hysteresis in the magnetoresistance observed at 5 K.\nThe magnetoresistance as a function of applied field was described by the\nKhosla-Fischer model for spin scattering of carriers in an impurity band.",
        "positive": "Prediction of Glass Elasticity from Free Energy Density of Topological\n  Constraints: Despite the critical importance of the elastic properties of modern\nmaterials, there is not a singular model that can predict the modulus to an\naccuracy needed for industrial glass design. To address this problem, we\npropose an approach to calculate the elastic modulus based on the free energy\ndensity of topological constraints in the glass-forming network. Our approach\nshows quantitatively accurate agreement with glasses across a variety of\ncompositional families. Moreover, using temperature-dependent constraint\ntheory, the temperature dependence of the modulus can also be predicted. Our\napproach is general and theoretically can be applied to any network glass."
    },
    {
        "anchor": "Dielectric constant of disordered phases of the smallest monoalcohols :\n  evidence for the hindered plastic crystal phase: With gradual temperature increase in premelting regions of solid phase of\nmethanol and high pressure phase of ethanol, and using novel procedure of\nseparation of electrode polarization effects, we are able to register the\ncontribution of relaxation process to low-frequency dielectric constant. This\ncontribution is about half the liquid's dielectric constant near temperature of\nsolidification , and is almost an order of magnitude higher than reported\nearlier for ambient pressure phase of methanol. As opposed to dielectric\nconstant of water at ambient pressure, which does not change much during\ncrystallization, our finding indicates the hindrance of molecule rotation in\norientationally disordered phases of monoalcohols. Similar dielectric responses\nof ambient pressure methanol and high-pressure phase of ethanol imply existence\nof hindered plastic crystal phase of ethanol (not observed at low pressures).\nWe also have found some dynamic disorder in nominally fully ordered phase of\nthese monoalcohols ($\\alpha$-phase of methanol and low-pressure phase of\nethanol), the contribution of this disorder being dependent on external\nconditions (e.g. temperature), and increasing at approaching the order-disorder\ntransition. On the other hand, the amplitude of dielectric responce in hindered\nplastic crystal phases is almost independent of temperature.",
        "positive": "Stability of an Exciton bound to an Ionized Donor in Quantum Dots: Total energy, binding energy, recombination rate (of the electron hole pair)\nfor an exciton (X) bound in a parabolic two dimensional quantum dot by a donor\nimpurity located on the z axis at a distance d from the dot plane, are\ncalculated by using the Hartree formalism with a recently developed numerical\nmethod (PMM) for the solution of the Schroedinger equation. As our analysis\nindicates there is a critical dot radius such that for radius less than the\ncritical radius the complex is unstable and with an increase of the impurity\ndistance this critical radius increases. Furthermore, there is a critical value\nof the mass ratio such that for mass ratio less than the critical value the\ncomplex is stable. The appearance of this stability condition depends both on\nthe impurity distance and the dot radius, in a way that with an increase of the\nimpurity distance we have an increase in the maximum dot radius where this\nstability condition appears. For dot radii greater than this maximum dot radius\n(for fixed impurity distance) the complex is always stable."
    },
    {
        "anchor": "Understanding the origin of the particularly small and anisotropic\n  thermal expansion of MOF-74: Metal-organic frameworks often display large positive or negative thermal\nexpansion coefficients. MOF-74, a material envisioned for many applications\ndoes not display such a behavior. For this system, temperature-dependent x-ray\ndiffraction reveals particularly small negative thermal expansion coefficients\nperpendicular and positive ones parallel to the hexagonally arranged pores. The\nobserved trends are explained by combining state-of-the-art density-functional\ntheory calculations with the Gr\\\"uneisen theory of thermal expansion, which\nallows tracing back thermal expansion to contributions of individual phonons.\nOn the macroscopic level, the small thermal expansion coefficients arise from\ntwo aspects: compensation effects caused by the large coupling between stress\nand strain perpendicular to the pores and the small magnitudes of the mean\nGr\\\"uneisen tensor elements, $\\langle\\gamma\\rangle$, which provide information\non how strains in the material influence its phonon frequencies. To understand\nthe small mean Gr\\\"uneisen tensor in MOF-74, the individual mode contributions\nare analyzed based on the corresponding atomic motions. This reveals that only\nthe lowest frequency modes up to ~3 THz provide non-negligible contributions,\nsuch that $\\langle\\gamma\\rangle$ drops sharply at higher temperatures. These\nconsiderations reveal how the details of the anharmonic properties of specific\nphonon bands determine the magnitude and sign of thermal expansion in a\nprototypical material like MOF-74.",
        "positive": "Electronic structure and energy level schemes of RE3+:LaSi3N5 and\n  RE2+:LaSi3N5-xOx phosphors (RE= Ce, Pr, Nd, Pm, Sm, Eu) from first principles: First principles calculations of rare earth (RE)-doped LaSi3N5 host lattice\nare performed to obtain the electronic structure, the band gap (BG), and the\ncharacter of electronic transitions. Doping with both trivalent and bivalent RE\ncations is inspected. RE 4f states form two bands of occupied and unoccupied\nstates separated by ~5 eV. In RE3+-doped compounds 4f states are shifted by ~6\neV to more negative energies compared with RE2+-compounds. This stabilization\ncauses that RE3+ 4f bands are in a different position relative to the valence\nband and the conduction band than RE2+ 4f bands and therefore different\nelectronic transitions apply. BG of RE3+-compounds decreases from ~4.6 eV (Ce)\nto ~0.5 eV (Eu). Except for Ce3+, exhibiting the 4f-5d transition, other\nRE3+-compounds show the charge transfer of the p - 4f character. BG of\nRE2+-compounds increases from ~0.80 eV (Ce, Pr) to ~0.95 eV (Nd, Pm), ~1.43 eV\n(Sm), and ~3.28 eV (Eu) and the electronic transition is of the 4f-5d\ncharacter. The energy level scheme constructed from ab initio calculated\nelectronic structures agrees well with the experimental energy level diagram.\nThe agreement demonstrates the reliability of the hybrid functional HSE06 to\ndescribe correctly bands of nonbonding RE 4f electrons."
    },
    {
        "anchor": "Anomalous behavior of the $E_u^1$ infrared-active phonon mode in a\n  Bi$_{2-x}$Sr$_x$Se$_3$ crystal: We have studied spectral evolution of the $E_u^1$ phonon line of a\ntopological insulator Bi$_{2-x}$Sr$_x$Se$_3$ with temperature. Unlike the\nRaman-active phonons, the $E_u^1$ mode demonstrates softening upon cooling the\ncrystal, and the corresponding spectral line acquires a pronounced Fano-like\nshape at temperatures $T\\lesssim100$ K. We interpret the latter effect as a\nsignature of specific coupling of the bulk infrared active phonons to surface\nDirac electrons. Using coherent resonant excitation of the $E_u^1$ mode as a\nsurface sensitive tool, we have detected softening of the surface counterpart\nof the bulk $E_u^1$ phonon mode upon strontium doping. This observation can be\nan evidence of enhanced electron-phonon interaction at the surface of the\nBi$_{2-x}$Sr$_x$Se$_3$ crystal.",
        "positive": "Enhanced photostrictive actuation in freestanding ferroelectric\n  membranes: Complex oxides offer a range of functional properties and recent advances in\nfabrication of freestanding membranes of these oxides have enabled enhanced\nfunctionality and novel manipulation strategies. Here, we demonstrate\nphotoactuation on freestanding thin film resonators of ferroelectric Barium\nTitanate (BaTiO$_3$) and paraelectric Strontium Titanate (SrTiO$_3$). The\nmembranes act as nano-drums, oscillating at their natural resonance frequency\nwhen illuminated by a frequency-modulated laser. Upon illumination, large\nout-of-plane deflections develop in BaTiO$_3$ membranes, two orders of\nmagnitude larger than in SrTiO$_3$ ones, providing evidence for a ferroelectric\norigin of their large photoresponse. Time-resolved X-ray micro-diffraction\nunder illumination and temperature-dependent vibrometry provide combined\nevidence for a photostrictive strain in BaTiO$_3$ originated from partial\nscreening of polarization by photo-excited carriers. These findings emphasise\nthe pivotal role of light-matter interaction and its manifestation in\nferroelectrics such as photostriction, and demonstrate the potential of\nfreestanding ferroelectric membranes as wireless remote optomechanical devices\nfor applications such as photo-actuators and sensors."
    },
    {
        "anchor": "Direct observation of N\u00e9el-type skyrmions and domain walls in a\n  ferrimagnetic DyCo$_3$ thin film: Isolated magnetic skyrmions are stable, topologically protected spin textures\nthat are at the forefront of research interests today due to their potential\napplications in information technology. A distinct class of skyrmion hosts are\nrare earth - transition metal (RE-TM) ferrimagnetic materials. To date, the\nnature and the control of basic traits of skyrmions in these materials are not\nfully understood. We show that for an archetypal ferrimagnetic material\nDyCo$_3$ that exhibits a strong perpendicular anisotropy, the ferrimagnetic\nskyrmion size can be tuned by an external magnetic field. Moreover, by taking\nadvantage of the high spatial resolution of scanning transmission X-ray\nmicroscopy (STXM) and utilizing a large x-ray magnetic linear dichroism (XMLD)\ncontrast that occurs naturally at the RE resonant edges, we resolve the nature\nof the magnetic domain walls of ferrimagnetic skyrmions. We demonstrate that\nthrough this method one can easily discriminate between Bloch and N\\'eel type\ndomain walls for each individual skyrmion. For all isolated ferrimagnetic\nskyrmions, we observe that the domain walls are of N\\'eel-type. This key\ninformation is corroborated with results of micromagnetic simulations and\nallows us to conclude on the nature of the Dzyaloshinskii-Moriya interaction\n(DMI) which concurs to the stabilisation of skyrmions in this ferrimagnetic\nsystem. Establishing that an intrinsic DMI occurs in RE-TM materials will also\nbe beneficial towards a deeper understanding of chiral spin texture control in\nferrimagnetic materials.",
        "positive": "On the Structural Stability and Optical Properties of Germanium-based\n  Schwarzites: A Density Functional Theory Investigation: Since graphene was synthesized the interest for building new 2D and 3D\nstructures based on the carbon allotropes has been growing every day. One of\nthese 3D structures is know as carbon schwarzites. Schwarzites consist of\ncarbon nanostructures possessing the shape of Triply-Periodic Minimal Surfaces\n(TPMS), which is characterized by a negative Gaussian curvature introduced by\nthe presence of carbon rings with more than six atoms. Some examples of\nschwarzite families include: primitive (P), gyroid (G) and diamond (D).\nPrevious studies considering different element species of schwarzites have\ninvestigated the mechanical, electrical and thermal properties. In this work,\nwe investigated the stability of germanium (Ge) schwarzites using density\nfunctional theory with GGA exchange-correlation functional. We chose one\nstructure of each family (P8bal), (G688) and (D688). It was observed that\nregions usually flat in carbon schwarzites acquires buckled configurations as\npreviously observed on silicene and germanene monolayers. The investigated\nstructures presented a semiconducting bandgap ranging from $0.13$ to $0.27$ eV.\nWe also performed calculations of optical properties within the linear regime,\nwhere it was shown that Ge schwarzites structures absorb light from infrared to\nultra-violet frequencies. Therefore, our results open new perspectives of\nmaterials that can be used in optelectronics devices application."
    },
    {
        "anchor": "Triplet Exciton Generation in Bulk-Heterojunction Solar Cells based on\n  Endohedral Fullerenes: Organic bulk-heterojunctions (BHJ) and solar cells containing the trimetallic\nnitride endohedral fullerene 1-[3-(2-ethyl)hexoxy\ncarbonyl]propyl-1-phenyl-Lu3N@C80 (Lu3N@C80-PCBEH) show an open circuit voltage\n(VOC) 0.3 V higher than similar devices with [6,6]-phenyl-C[61]-butyric acid\nmethyl ester (PC61BM). To fully exploit the potential of this acceptor molecule\nwith respect to the power conversion efficiency (PCE) of solar cells, the short\ncircuit current (JSC) should be improved to become competitive with the state\nof the art solar cells. Here, we address factors influencing the JSC in blends\ncontaining the high voltage absorber Lu3N@C80-PCBEH in view of both\nphotogeneration but also transport and extraction of charge carriers. We apply\noptical, charge carrier extraction, morphology, and spin-sensitive techniques.\nIn blends containing Lu3N@C80-PCBEH, we found 2 times weaker photoluminescence\nquenching, remainders of interchain excitons, and, most remarkably, triplet\nexcitons formed on the polymer chain, which were absent in the reference\nP3HT:PC61BM blends. We show that electron back transfer to the triplet state\nalong with the lower exciton dissociation yield due to intramolecular charge\ntransfer in Lu3N@C80-PCBEH are responsible for the reduced photocurrent.",
        "positive": "Elucidation of the electronic structure of semiconducting single-walled\n  carbon nanotubes by electroabsorption spectroscopy: We report benchmark calculations of electroabsorption in semiconducting\nsingle-walled carbon nanotubes to provide motivation to experimentalists to\nperform electroabsorption measurement on these systems. We show that\nelectroabsorption can detect continuum bands in different energy manifolds,\neven as other nonlinear absorption measurements have failed to detect them.\nDirect determination of the binding energies of excitons in higher manifolds\nthereby becomes possible. We also find that electroabsorption can provide\nevidence for Fano-type coupling between the second exciton and the lowest\ncontinuum band states."
    },
    {
        "anchor": "Neutron methods for the direct determination of the magnetic induction\n  in thick films: We review different neutron methods which allow extracting directly the value\nof the magnetic induction in thick films: Larmor precession, Zeeman spatial\nbeam-splitting and neutron spin resonance. Resulting parameters obtained by the\nneutron methods and standard magnetometry technique are presented and compared.\nThe possibilities and specificities of the neutron methods are discussed.",
        "positive": "Comment on ``Comparison of the $Cc$ and $R3c$ space groups for the\n  superlattice phase of Pb(Zr$_{0.52}$Ti$_{0.48}$)O$_3$'': The two-phase (space groups $Cc$ and $Cm$) structural model recently proposed\nfor the modeling of the neutron powder diffaction pattern collected on\nPb(Zr$_x$Ti$_{1-x}$)O$_3$ (PZT) sample with $x\\approx 0.52$ [R. Ranjan, A. K.\nSingh, Ragini, and D. Pandey. \\textit{Phys. Rev. B} \\textbf{71}, 092101 (2005)]\nis shown to neglect the $hkl$ dependent (anisotropic) line broadening. The most\nserious problem with this model is that it assigns octahedral tilts to a wrong\nphase. Instead of correctly taking the anisotropic line broadening into\naccount, this model used low symmetry phases to minimize the residuals during\nRietveld refinement. The essential features of a model taking the $hkl$\ndependent line broadening into account are summarized. It has already been\nreported that once the anisotropic line broadening, revealed by high resolution\nneutron powder diffraction instrument, is correctly taken into account the\nmodel with $R3c$ and $Cm$ space group symmetries describes all Bragg peaks and\ntheir intensities well [J. Frantti, S. Eriksson, S. Hull, V. Lantto, H.\nRundl\\\"of, and M. Kakihana. \\textit{J. Phys.: Condens. Matter} \\textbf{15},\n6031 (2003).]. It was further shown that the $Cm+R3c$ model is consistent with\nthe structural features observed at other compositions and temperatures, which\nis particularly important in the vicinity of the phase boundary. Also problems\nrelated to sample preparation and data collection are pointed out."
    },
    {
        "anchor": "Vertical Spin Transport in Al with Pd/Al/Ni80Fe20 Trilayer Films at Room\n  Temperature by Spin Pumping: Spin pumping enables the vertical transport of pure spin current through Al\nin a Pd/Al/Ni80Fe20(Py) trilayer film, in which the Py acts as a spin battery.\nThe spin current injected into the Al flows through the Al to reach the Pd,\nresulting in the generation of electromotive forces due to the inverse spin\nHall effect in the Pd. The electromotive forces decreased with increasing\nthickness of the Al layer. A simple model based on the theory by Tserkovnyak et\nal., [Phys. Rev. B, 66, 224403 (2002)] allows an estimation of the spin\ncoherence of the perpendicular spin transport in the Al of 61 nm. This\ncomparatively short coherence is attributed to a reduction in spin pumping\nefficiency because of the roughness of the Al/Py interface.",
        "positive": "Closing the gap between spatial and spin dynamics of electrons at the\n  metal-to-insulator transition: We combine extensive precision measurements of the optically detected spin\ndynamics and magneto-transport measurements in a contiguous set of n-doped bulk\nGaAs structures in order to unambiguously unravel the intriguing but complex\ncontributions to the spin relaxation at the metal-to-insulator transition\n(MIT). Just below the MIT, the interplay between hopping induced loss of spin\ncoherence and hyperfine interaction yields a maximum spin lifetime exceeding\n800~ns. At slightly higher doping concentrations, however, the spin relaxation\ndeviates from the expected Dyakonov-Perel mechanism which is consistently\nexplained by a reduction of the effective motional narrowing with increasing\ndoping concentration. The reduction is attributed to the change of the dominant\nmomentum scattering mechanism in the metallic impurity band where scattering by\nlocal conductivity domain boundaries due to the intrinsic random distribution\nof donors becomes significant. Here, we fully identify and model all intricate\ncontributions of the relevant microscopic scattering mechanisms which allows\nthe complete quantitative modeling of the electron spin relaxation in the\nentire regime from weakly interacting up to fully delocalized electrons."
    },
    {
        "anchor": "First-principles study of structural, vibrational and lattice dielectric\n  properties of hafnium oxide: Crystalline structures, zone-center phonon modes, and the related dielectric\nresponse of the three low-pressure phases of HfO2 have been investigated in\ndensity-functional theory using ultrasoft pseudopotentials and a plane-wave\nbasis. The structures of low-pressure HfO2 polymorphs are carefully studied\nwith both the local-density approximation (LDA) and the generalized gradient\napproximation (GGA). The fully relaxed structures obtained with either\nexchange-correlation scheme agree reasonably well with experiment, although LDA\nyields better overall agreement. After calculating the Born effective charge\ntensors and the force-constant matrices by finite-difference methods, the\nlattice dielectric susceptibility tensors for the three HfO2 phases are\ncomputed by decomposing the tensors into the contributions from individual\ninfrared-active phonon modes.",
        "positive": "High-performance graphene-based electrostatic field sensor: Electrostatic sensing technology is widely utilized in both military and\ncivilian applications, including electrostatic prevention in gas stations and\nvarious electronic devices. The high sensitivity of electrostatic sensor is\ncapable to detect not only weak electrostatic charges, but also the weak\ndisturbance of electrostatic field in distant. Here, we present a\nhigh-performance graphene-based electrostatic sensor. Combining the ultrahigh\nmobility of graphene and the long lifetime of carriers in lightly doped SiO2/Si\nsubstrate, our device achieves a fast response of ~2 us and detection limit of\nelectrostatic potential as low as ~5 V, which is improved by an order of\nmagnitude as compared to commercial product. The proposed device structure\nopens a promising pathway to high-sensitive electrostatic detection, and also\ngreatly facilitates the development of novel sensors, e.g. portable and\nflexible electrostatic sensor."
    },
    {
        "anchor": "CrysXPP:An Explainable Property Predictor for Crystalline Materials: We present a deep-learning framework, CrysXPP, to allow rapid prediction of\nelectronic, magnetic and elastic properties of a wide range of materials with\nreasonable precision. Although our work is consistent with several recent\nattempts to build deep learning-based property predictors, it overcomes some of\ntheir limitations. CrysXPP lowers the need for a large volume of tagged data to\ntrain a deep learning model by intelligently designing an autoencoder CrysAE\nand passing the structural information to the property prediction process. The\nautoencoder in turn is trained on a huge volume of untagged crystal graphs, the\ndesigned loss function helps in capturing all their important structural and\nchemical information. Moreover, CrysXPP uses only a small amount of tagged data\nfor property prediction, and also trains a feature selector that provides\ninterpretability to the results obtained. We demonstrate that CrysXPP\nconvincingly performs better than all the competing and recent baseline\nalgorithms across seven diverse set of properties. Most notably, when given a\nsmall amount of experimental data, CrysXPP is consistently able to outperform\nconventional DFT. We release the large pretrained model CrysAE so that it could\nbe fine-tuned using small amount of tagged data by the research community on\nvarious applications with restricted data source.",
        "positive": "Effect of pressure on the dynamics of iodine defects in MAPI: An\n  atomistic simulation: The diffusion of iodine defects has been considered the most important\ndegradation mechanism of methylammonium lead iodine (MAPI) in solar cells. The\npresent study demonstrates the importance of the pressure inside this material\non the dynamics of iodine defects, using molecular dynamics simulations. It is\nknown that the diffusion coefficient of an iodine vacancy is an order of\nmagnitude higher than that of interstitial iodine. We show that this difference\nsystematically increases with increased tensile strain and that both diffusion\ncoefficients tend to zero when a compressive strain is applied. This result\nsuggests that compression of the MAPI can be a good solution to reduce its\ndegradation rate. %Also, different methods of determining the diffusion\ncoefficient, including mean squared displacement (MSD) and velocity\nauto-correlation function, are discussed and applied to the case of ${\\rm\nV}_{\\rm I}$. Besides, the statistical aspect of deriving the diffusion\ncoefficient from the mean squared displacement (MSD) is discussed in terms of\nthe initial conditions (positions and velocities) of the atoms and the\nsimulation time, considering different seeds of the pseudo-random number\ngenerator used in the simulations performed with the LAMMPS software."
    },
    {
        "anchor": "Limits to Poisson's ratio in isotropic materials: A long-standing question is why Poisson's ratio v nearly always exceeds 0.2\nfor isotropic materials, whereas classical elasticity predicts v to be between\n-1 to 1/2. We show that the roots of quadratic relations from classical\nelasticity divide v into three possible ranges: -1 < v <= 0, 0 <= v <= 1/5, and\n1/5 <= v < 1/2. Since elastic properties are unique there can be only one valid\nset of roots, which must be 1/5 <= v < 1/2 for consistency with the behavior of\nreal materials. Materials with Poisson's ratio outside of this range are rare,\nand tend to be either very hard (e.g., diamond, beryllium) or porous (e.g.,\nauxetic foams); such substances have more complex behavior than can be\ndescribed by classical elasticity. Thus, classical elasticity is inapplicable\nwhenever v < 1/5, and the use of the equations from classical elasticity for\nsuch materials is inappropriate.",
        "positive": "Computational Understandings of the Cation Configuration Dependent Redox\n  Activities and Oxygen Dimerizations in Li$_{1.22}$Ni$_{0.22}$Mn$_{0.56}$O$_2$\n  Cathode: Understanding the lattice oxygen dimerization is quite essential for the\noptimal design for the Li-rich Mn-based cathode materials. In this work, based\non the density functional theory (DFT) calculations, a Ni-honeycomb Li-Ni-Mn\ncation configuration for Li$_{1.22}$Ni$_{0.22}$Mn$_{0.56}$O$_2$ cathode was\ncarefully proposed and examined, which can coexist with the well-known\nLi-honeycomb structure in the experimentally synthesized\nLi$_{1.2}$Ni$_{0.2}$Mn$_{0.6}$O$_2$ samples. Li-Ni-Mn cation configurations\nhave significant impacts on oxygen redox activities and oxygen dimerizations in\nthe delithiated Li$_x$Ni$_{0.22}$Mn$_{0.56}$O$_2$. There is no necessary\nconsistency between the high lattice oxygen redox activity and easy oxygen\ndimerization, such as the Li-honeycomb structures showing higher redox\nactivities and higher activation energy barriers to prohibit oxygen\ndimerizations than Ni-honeycomb structures. Avoiding the Ni-honeycomb\nstructures with more favorable lattice oxygen dimerization and making full use\nof the Li-honeycomb structures with better redox activities is important to\noptimally design the high-performance Li-rich Mn-based cathode materials."
    },
    {
        "anchor": "Singularities of Magnetic and Elastic Characteristics of La2/3Ba1/3MnO3:\n  Analysis of Martensitic Kinetics: A coordinated temperature behavior of magnetic susceptibility and internal\nfriction has been observed in the La2/3Ba1/3MnO3 manganite in the temperature\nregion of the crystal phase separation 5-340 K. Stepwise temperature behavior\nof the susceptibility of the single crystal sample and corresponding singular\nbehavior of the internal friction in the polycrystalline manganite have been\nfound. These small-scale features of the temperature dependences of the\nsusceptibility and the internal friction are considered to be a reflection of\nmartensitic kinetics of the structural phase transformation R3c-Imma in the 200\nK temperature region.",
        "positive": "Ferromagnetic InMnAs on InAs Prepared by Ion Implantation and Pulsed\n  Laser Annealing: Ferromagnetic InMnAs has been prepared by Mn ion implantation and pulsed\nlaser annealing. The InMnAs layer reveals a saturated magnetization of 2.6\nmu_B/Mn at 5 K and a perpendicular magnetic anisotropy. The Curie temperature\nis determined to be 46 K, which is higher than those in previous reports with\nsimilar Mn concentrations. Ferromagnetism is further evidenced by the large\nmagnetic circular dichroism."
    },
    {
        "anchor": "Tailing Magnetoelectric properties of Cr2Ge2Te6 by Engineering\n  Covalently bonded Cr Self-intercalation: Ferromagnetic Half-metal: Two-dimensional intrinsic ferromagnetic half-metal (HM) are important for the\nspintronics. Manipulating the interlayer magnetic coupling of van der Waals\nmagnetic materials is an important method to control magnetoelectric\nproperties, which is especially useful for the spintronics. Here, based on\nsystematical research of CrGeTe3 (CGT) bilayer and multilayers with s of\nself-intercalated (SI) Cr atom, we find that self-intercalation can enhance the\ninterlayer magnetic coupling. The super-exchange interaction still dominates\ninterlayer magnetic exchange interaction, which results in ferromagnetic\ncoupling between neighboring vdW layers. CGT bilayer keeps HM with FM order\nafter Cr self-intercalation, independent of self-intercalated Cr (CrSI) atoms'\nconcentration. Most importantly, self-intercalated CrGeTe3 (SI-CGT) bilayers\nshow ferromagnetic HM, independent of stacking orders. Moreover, SI-CGT\nmultilayers keep FM order, independent of films' thickness. However, SI-CGT\nmultilayers transform from HM into normal spin-polarized metal, as the states\nat the Fermi-level increases. Moreover, magnetic anisotropy energy (MAE) of\nSI-CGT-AA and SI-CGT-AB are -0.160 and -0.42 meV/.f.u., which are modulated by\nCrSI atoms. The MAE of SI-CGT-AA and SI-CGT-AB are different, as the\nhybridization interaction between Cr's d orbitals is different. SI-CGT\nmultilayers' magnetic easy axis (EA) switches from [001] of CGT to [100]\ndirection, independent of stacking orders. It origins that MAE mainly\ncontributed by hybridization between Te atoms' px and py, py and pz orbitals is\nobvious weakened as CrSI is introduced. SI-CGT multilayers show good dynamical,\nthermal, and magnetic stability at 300 and 500 K. These findings find a\npromising way to manipulate interlayer exchange interaction and magnetoelectric\nproperties of CGT multilayers and other vdW magnets.",
        "positive": "Non-collinear Magnetic states of Mn5Ge3 compound: Mn5Ge3 thin films epitaxially grown on Ge(111) exhibit metallic conductivity\nand strong ferromagnetism up to about 300 K. Recent experiments suggest a\nnon-collinear spin structure. In order to gain deep insights into the magnetic\nstructure of this compound, we have performed fully unconstrained ab-initio\npseudopotential calculations within density functional theory, investigating\nthe different magnetic states corresponding to Collinear (C) and Non-Collinear\n(NC) spin configurations. We focus on their relative stability under pressure\nand strain field. Under pressure, the C and NC configurations are degenerate,\nsuggesting the possible occurrence of accidental magnetic degeneracy also in\nMn5Ge3 real samples. We found a continuous transition from a ferromagnetic C\nlow-spin state at small volumes to a NC high-spin state at higher volumes.\nRemarkably, the degeneracy is definitely removed under the effect of uniaxial\nstrain: in particular, NC spin configurations is favoured under tensile\nuniaxial strain."
    },
    {
        "anchor": "Chern insulator at a magnetic rocksalt interface: Considerable efforts have recently been devoted to the experimental\nrealization of a two-dimensional Chern insulator, i.e., a system displaying a\nquantum anomalous Hall effect. However, existing approaches such as those based\non magnetic doping of topological-insulator thin films have resulted in small\nband gaps, restricting the effect to low temperatures. We use first-principles\ncalculations to demonstrate that an interface between thin films of the\ntopologically trivial ferromagnetic insulators EuO and GdN can result in a band\ninversion and a non-zero Chern number. Both materials are stoichiometric and\nthe interface is non-polar and lattice-matched, which should allow this\ninterface to be achievable experimentally. We show that the band structure can\nbe tuned by layer thickness or epitaxial strain, and can result in Chern\ninsulators with gaps of over 0.1 eV.",
        "positive": "A DC magnetic metamaterial: Electromagnetic metamaterials are a class of materials which have been\nartificially structured on a subwavelength scale. They are currently the focus\nof a great deal of interest because they allow access to previously\nunrealisable properties like a negative refractive index. Most metamaterial\ndesigns have so far been based on resonant elements, like split rings, and\nresearch has concentrated on microwave frequencies and above. In this work, we\npresent the first experimental realisation of a non-resonant metamaterial\ndesigned to operate at zero frequency. Our samples are based on a\nrecently-proposed template for an anisotropic magnetic metamaterial consisting\nof an array of superconducting plates. Magnetometry experiments show a strong,\nadjustable diamagnetic response when a field is applied perpendicular to the\nplates. We have calculated the corresponding effective permeability, which\nagrees well with theoretical predictions. Applications for this metamaterial\nmay include non-intrusive screening of weak DC magnetic fields."
    },
    {
        "anchor": "Step energies and equilibrium shape of strained monolayer islands: Using a simple atomistic model of anharmonic nearest-neighbors interaction,\nwe have calculated the step energies of strained hexagonal monolayer islands.\nThese have been found to decrease with the absolute value of the misfit due to\nthe strain relaxation at steps. The effect is significantly more pronounced in\nthe case of positive misfit owing to the stronger repulsive interatomic forces.\nFurthermore, (111)-faceted steps are favored at positive misfit (compressed\nislands) and, to a lesser extent, (100)-faceted steps at negative misfits\n(tensile islands). The result is rationalized in terms of the different bonding\ngeometries at step edges and a comparison with experiments is included. Thus,\nthe equilibrium shape transforms from regular hexagons at zero misfit to\nthreefold symmetric hexagons with increasing misfit.",
        "positive": "Adsorption and dissociation of water on Zr(0001) with density-functional\n  theory studies: The adsorption and dissociation of isolated water molecule on Zr(0001)\nsurface are theoretically investigated for the first time by using\ndensity-functional theory calculations. Two kinds of adsorption configurations\nwith almost the same adsorption energy are identified as the locally stable\nstates, i.e., the flat and upright configurations respectively. It is shown\nthat the flat adsorption states on the top site are dominated by the\n1$b_{1}$-$d$ band coupling, insensitive to the azimuthal orientation. The\ndiffusion between adjacent top sites reveals that the water molecule is very\nmobile on the surface. For the upright configuration, we find that besides the\ncontribution of the molecular orbitals 1$b_{1}$ and 3$a_{1}$, the\nsurface$\\rightarrow$water charge transfer occurring across the Fermi level also\nplays an important role. The dissociation of H$_{2}$O is found to be very\nfacile, especially for the upright configuration, in good accordance with the\nattainable experimental results. The present results afford to provide a\nguiding line for deeply understanding the water-induced surface corrosion of\nzirconium."
    },
    {
        "anchor": "Quantum transport of slow charge carriers in quasicrystals and\n  correlated systems: We show that the semi-classical model of conduction breaks down if the mean\nfree path of charge carriers is smaller than a typical extension of their\nwavefunction. This situation is realized for sufficiently slow charge carriers\nand leads to a transition from a metallic like to an insulating like regime\nwhen scattering by defects increases. This explains the unconventional\nconduction properties of quasicrystals and related alloys. The conduction\nproperties of some heavy fermions or polaronic systems, where charge carriers\nare also slow, present a deep analogy.",
        "positive": "Magnetoelectric response of multiferroic BiFeO3 and related materials: We present a first-principles scheme for computing the magnetoelectric\nresponse of multiferroics. We apply our method to BiFeO3 (BFO) and related\ncompounds in which Fe is substituted by other magnetic species. We show that\nunder certain relevant conditions -- i.e., in absence of incommensurate spin\nmodulation, as in BFO thin films and some BFO-based solid solutions -- these\nmaterials display a large linear magnetoelectric response. Our calculations\nreveal the atomistic origin of the coupling and allow us to identify the most\npromising strategies to enhance it."
    },
    {
        "anchor": "Structural, elastic, optical properties and quasiparticle band structure\n  of solid cyanuric triazide: In this letter, we report the structural, elastic, and quasiparticle band\nstructure of cynauric triazide. The structural properties using a dispersion\ncorrected method to treat van der Waals (vdW) forces offers a significant\nimprovement in the description of the ground state properties. The predicted\nbulk modulus from the equation of state and the elastic constants are\nconsistent and the magnitude lies in the order of secondary explosives. Then,\nthe G$_0$W$_0$ approximation is used to study the band structure and an\nindirect band gap of 6.33 eV is obtained. Finally, we have calculated the\noptical and detonation characteristics at ambient pressure.",
        "positive": "Visualization of optical polarization transfer to photoelectron spin\n  vector emitted from the spin-orbit coupled surface state: Similar to light polarization that is selected by a superposition of optical\nbasis, electron spin direction can be controlled through a superposition of\nspin basis. We investigate such a spin interference occurring in photoemission\nof the spin-orbit coupled surface state in Bi2Se3 by using spin- and\nangle-resolved photoemission spectroscopy combined with laser light source\n(laser-SARPES). Our laser-SARPES with three-dimensional spin detection and\ntunable laser polarization including elliptical and circular polarization\nenables us to directly visualize how the direction of the fully-polarized\nphotoelectron spin changes according to the optical phase and orientation of\nthe incident laser polarization. By this advantage of our laser-SARPES, we\ndemonstrate that such optical information can be projected to the\nthree-dimensional spin vector of the photoelectrons. Our results, therefore,\npresent a novel spin-polarized electron source permitting us to optically\ncontrol the pure spin state pointing to the arbitrary direction."
    },
    {
        "anchor": "Synthesis, Structure and Properties of Boron and Nitrogen Doped Graphene: Two-dimensional graphene exhibits many fascinating properties such as\nballistic electronic conduction and quantum Hall effect at room temperature.1-4\nGraphene doped electrochemically or through charge-transfer with electron-donor\nand -acceptor molecules,5-7 shows marked changes in electronic structure, with\ncharacteristic signatures in the Raman spectra.5-10 Substitutional doping,\nuniversally used in tuning properties of semiconductors, could be a powerful\ntool to control the electronic properties of graphene. Here, we present the\nstructure and properties of boron and nitrogen doped graphenes, obtained by\nmore than one method involving arc discharge in appropriate gaseous atmosphere,\nby using modified graphite electrode or by the transformation of nano-diamond.\nUsing a combination of experiment and firstprinciples theory, we demonstrate\nsystematic changes in the carrier-concentration and electronic structure of\ngraphenes with B/N-doping, accompanied by stiffening of the Gband and\nintensification of the defect related D-band in the Raman spectra. Such n/p -\ntype graphenes obtained without external fields or chemical agents should find\ndevice applications.",
        "positive": "Phonon Quasi-Particles and Anharmonic Free Energy in Complex Systems: We use a hybrid strategy to obtain anharmonic frequency shifts and lifetimes\nof phonon quasi-particles from first principles molecular dynamics simulations\nin modest size supercells. This approach is effective irrespective of crystal\nstructure complexity and facilitates calculation of full anharmonic phonon\ndispersions, as long as phonon quasi-particles are well defined. We validate\nthis approach to obtain anharmonic effects with calculations in\nMgSiO3-perovskite, the major Earth forming mineral phase. First, we reproduce\nirregular temperature induced frequency shifts of well characterized Raman\nmodes. Second, we combine the phonon gas model (PGM) with quasi-particle\nfrequencies and reproduce free energies obtained using thermodynamic\nintegration. Combining thoroughly sampled quasi-particle dispersions with the\nPGM we then obtain first-principles anharmonic free energy in the thermodynamic\nlimit (N right arrow infinity)."
    },
    {
        "anchor": "Atomic Scale Surface Segregation in Copper-Gold Nanoparticles: In this work, we combine electron microscopy measurements of the surface\ncompositions in Cu-Au nanoparticles and atomistic simulations to investigate\nthe effect of gold segregation. While this mechanism has been extensively\ninvestigated within Cu-Au in the bulk state, it was never studied at the atomic\nlevel in nanoparticles. By using energy dispersive X-ray analysis across the\n(100) and (111) facets of nanoparticles, we provide evidence of gold\nsegregation in Cu$_{3}$Au and CuAu$_{3}$ nanoparticles in the 10 nm size range\ngrown by epitaxy on a salt surface with high control of the nanoparticles\nmorphology. To get atomic-scale insights into the segregation properties in\nCu-Au nanoparticles on the whole composition range, we perform Monte Carlo\ncalculations employing $N$-body interatomic potentials. These simulations\nconfirm this effect by showing a complete segregation of Au in the (100) and\n(111) faces of a truncated octahedron for gold nominal composition of the alloy\nabove 70\\% and 60\\% respectively. Furthermore, we show that there is no size\neffect on the segregation behaviour since we evidence the same oscillating\nconcentration profile from surface to the nanoparticles core as in the bulk.\nThese results can shed new lights in the interpretation of the enhanced\nreactivity, selectivity and stability of Cu-Au nanoparticles in various\ncatalytic reactions.",
        "positive": "Engineering decomposition-resilience and de-coalescence of GaN nanowire\n  ensembles: The rapidly increasing interest in nanowires (NWs) of GaN and associated\nIII-Nitrides for (opto-)electronic applications demands immediate addressal of\nthe technological challenges associated with both NW-growth and device\nprocessing. Towards this end, we demonstrate in this work an approach to\nsuppress thermal decomposition of GaN NWs, which also serves to remedy the\neffect of NW-coalescence during growth. While both these effects are well-known\nto be major hurdles in the development of GaN-NW-devices, reliable methods to\ntackle these issues have not been reported so far. We show that by providing a\nthin AlN cap layer, which epitaxially grows only on the top-facet of the GaN\nNWs, thermal decomposition can be almost completely suppressed. Thermal\nannealing of GaN NW-ensembles, post AlN-capping, leads to selective\ndecomposition of uncapped/partially-capped NWs, leaving behind (mostly)\nAlN-capped GaN NWs, with superior crystal- and luminescence characteristics.\nThis simple yet extremely effective approach may therefore serve as a very\ncrucial milestone in the roadmap of GaN-NW-based (opto-)electronic technology."
    },
    {
        "anchor": "Cluster magnetic octupole induced out-of-plane spin polarization in\n  antiperovskite antiferromagnet: Out-of-plane spin polarization {\\sigma}_z has attracted increasing interests\nof researchers recently, due to its potential in high-density and low-power\nspintronic devices. Noncollinear antiferromagnet (AFM), which has unique\n120{\\deg} triangular spin configuration, has been discovered to possess\n{\\sigma}_z. However, the physical origin of {\\sigma}_z in noncollinear AFM is\nstill not clear, and the external magnetic field-free switching of\nperpendicular magnetic layer using the corresponding {\\sigma}_z has not been\nreported yet. Here, we use the cluster magnetic octupole in antiperovskite AFM\nMn3SnN to demonstrate the generation of {\\sigma}_z. {\\sigma}_z is induced by\nthe precession of carrier spins when currents flow through the cluster magnetic\noctupole, which also relies on the direction of the cluster magnetic octupole\nin conjunction with the applied current. With the aid of {\\sigma}_z, current\ninduced spin-orbit torque (SOT) switching of adjacent perpendicular ferromagnet\nis realized without external magnetic field. Our findings present a new\nperspective to the generation of out-of-plane spin polarizations via\nnoncollinear AFM spin structure, and provide a potential path to realize\nultrafast high-density applications.",
        "positive": "The cooperative Jahn-Teller ordering investigation by absorption spectra\n  in $KDy(MoO_4)_2$: Absorption spectra fine structure of $KDy(MoO_4)_2$ in the region of\ncooperative Jahn-Teller type ordering was studied. Temperature anomalies in the\nspectra occurring at phase transformation correlate with the ultrasound\npeculiarities observed earlier. Based on the symmetry approaching, possible\nactivity of the irreducible representations of the rhombic $D_{2h}$ point group\nwas discussed, which lead to the incommensurate phase at cooperative ordering.\nIt was supposed, that coupled $A_u$-type phonon mode may lead to the\nincommensurate phase existence, which is possible at least in the temperature\nregion 17-12 K."
    },
    {
        "anchor": "Adsorption and Diffusion of F2 molecules on Pristine Graphene: The adsorption and diffusion of F2 molecules on pristine graphene have been\nstudied using first-principles calculations. For the diffusion of F2 from\nmolecular state in gas phase to the dissociative adsorption state on graphene\nsurface, a kinetic barrier is identified, which explains the inertness of\ngraphene in molecular F2 at room temperature, and its reactivity with F2 at\nhigher temperatures. Studies on the diffusion of F2 molecules on graphene\nsurface determine the energy barriers along the optimal diffusion pathways,\nwhich help to understand the high stability of fluorographene.",
        "positive": "Resonant addressing and manipulation of silicon vacancy qubits in\n  silicon carbide: Several systems in the solid state have been suggested as promising\ncandidates for spin-based quantum information processing. In spite of\nsignificant progress during the last decade, there is a search for new systems\nwith higher potential [D. DiVincenzo, Nature Mat. 9, 468 (2010)]. We report\nthat silicon vacancy defects in silicon carbide comprise the technological\nadvantages of semiconductor quantum dots and the unique spin properties of the\nnitrogen-vacancy defects in diamond. Similar to atoms, the silicon vacancy\nqubits can be controlled under the double radio-optical resonance conditions,\nallowing for their selective addressing and manipulation. Furthermore, we\nreveal their long spin memory using pulsed magnetic resonance technique. All\nthese results make silicon vacancy defects in silicon carbide very attractive\nfor quantum applications."
    },
    {
        "anchor": "Birefringence induced by antiferroelectric switching in transparent\n  polycrystalline $PbZr_{0.95}Ti_{0.05}O_{3}$ film: The most characteristic functional property of antiferroelectric materials is\nthe possibility to induce a phase transition from a non-polar to a polar phase\nby an electric field. Here, we investigate the effect of this field-induced\nphase transition on the birefringence change of $PbZr_{0.95}Ti_{0.05}O_{3}$. We\nuse a transparent polycrystalline $PbZr_{0.95}Ti_{0.05}O_{3}$ film grown on\n$PbTiO_{3}/HfO_{2}/SiO_{2}$ with interdigitated electrodes to directly\ninvestigate changes in birefringence in a simple transmission geometry. In\nspite of the polycrystalline nature of the film and its moderate thickness, the\nfield-induced transition produces a sizeable effect observable under a\npolarized microscope. The film in its polar phase is found to behave like a\nhomogeneous birefringent medium. The time evolution of this field-induced\nbirefringence provides information about irreversibilities in the\nantiferroelectric switching process and its slow dynamics. The change in\nbirefringence has two main contributions, one that responds briskly (~ 0.5 s),\nand a slower one that rises and saturates over a period of as long as 30\nminutes. Possible origins for this long saturation and relaxation times are\ndiscussed.",
        "positive": "Transfer doping of Graphene by Species of Extreme Work Function: Density functional calculations are used to explain the charge transfer\ndoping mechanism by which species physisorptively bonded to graphene can\nincrease its free hole or electron density, without giving rise to defects, and\nthus maintain a high carrier mobility. Typical dopants studied are FeCl3,\nAuCl3, SbF5, HNO3, MoO3, Cs2O and O2. These systems do not break the {\\pi}\nbonding of the basal plane are particularly important as these do not degrade\nthe carrier mobility. In contrast, more reactive radicals like -OH cause a\npuckering of the basal plane and thereby act as defects."
    },
    {
        "anchor": "A local Fock-exchange potential in Kohn-Sham equations: We derive and employ a local potential to represent the Fock exchange\noperator in electronic single-particle equations. This local Fock-exchange\n(LFX) potential is very similar to the exact exchange (EXX) potential in\ndensity functional theory (DFT). The practical software implementation of the\ntwo potentials (LFX and EXX) yields robust and accurate results for a variety\nof systems (semiconductors, transition metal oxides) where Hartree Fock and\npopular approximations of DFT typically fail. This includes examples\ntraditionally considered qualitatively inaccessible to calculations that omit\ncorrelation.",
        "positive": "Germanium atoll-islands on surface modified Si(111)-(7x7): This paper has been withdrawn by first author KM Seemann."
    },
    {
        "anchor": "Localized Wannier function based tight-binding models for\n  two-dimensional allotropes of bismuth: With its monoelemental composition, various crystalline forms and an\ninherently strong spin-orbit coupling, bismuth has been regarded as an ideal\nprototype material to expand our understanding of topological electronic\nstructures. In particular, two-dimensional bismuth thin films have attracted a\ngrowing interest due to potential applications in topological transistors and\nspintronics. This calls for an effective physical model to give an accurate\ninterpretation of the novel topological phenomena shown by two-dimensional\nbismuth. However, the conventional semi-empirical approach of adapting bulk\nbismuth hoppings fails to capture the topological features of two-dimensional\nbismuth allotropes because the electronic band topology is heavily influenced\nby crystalline symmetries as well as atom spacings. Here we provide a new\nparameterization using localized Wannier functions derived from the Bloch\nstates in first-principles calculations. We construct new tight-binding models\nfor three types of two-dimensional bismuth allotropes: a Bi (111) bilayer,\nbismuthene and a Bi(110) bilayer. We demonstrate that our tight-binding models\ncan successfully reproduce the band structures, symmetries and topological\nfeatures of these two-dimensional allotropes. We anticipate that these models\ncan be extended to other similar two-dimensional topological structures such as\nantimonene and arsenene. Moreover, these models can serve as a starting point\nfor investigating the electron/spin transport and electromagnetic response in\nlow-dimensional topological devices.",
        "positive": "Quantum Hall effect in multilayered massless Dirac fermion systems with\n  tilted cones: We report the first observation of Shubnikov-de Haas (SdH) oscillations and\nquantized Hall resistance in the multilayered massless Dirac fermion system\n$\\alpha$-(BEDT-TTF)$_2$I$_3$ with tilted cones. Holes were injected into the\nthin crystal fixed on a polyethylene naphthalate (PEN) substrate by contact\nelectrification. The detection of SdH oscillations whose phase was modified by\nBerry's phase $\\pi$ strongly suggested that the carrier doping was successful\nin this system. We succeeded in detecting the quantum Hall effect (QHE) with\nthe steps which is the essence of two dimensional Dirac fermion systems. The\nnumber of effectively doped layers was examined to be two in this device. We\nreveal that the correlation between effective layers plays an important role in\nQHE."
    },
    {
        "anchor": "The Effects of Next-Nearest-Neighbor Interactions on the Orientation\n  Dependence of Step Stiffness: Reconciling Theory with Experiment for Cu(001): Within the solid-on-solid (SOS) approximation, we carry out a calculation of\nthe orientational dependence of the step stiffness on a square lattice with\nnearest and next-nearest neighbor interactions. At low temperature our result\nreduces to a simple, transparent expression. The effect of the strongest trio\n(three-site, non pairwise) interaction can easily be incorporated by modifying\nthe interpretation of the two pairwise energies. The work is motivated by a\ncalculation based on nearest neighbors that underestimates the stiffness by a\nfactor of 4 in directions away from close-packed directions, and a subsequent\nestimate of the stiffness in the two high-symmetry directions alone that\nsuggested that inclusion of next-nearest-neighbor attractions could fully\nexplain the discrepancy. As in these earlier papers, the discussion focuses on\nCu(001).",
        "positive": "Origin of the Bauschinger Effect in Amorphous Solids: We study the structural origin of the Bauschinger effect by accessing\nnumerically the local plastic thresholds in the steady state flow of a\ntwo-dimensional model glass under athermal quasistatic deformation. More\nspecifically, we compute the local residual strength, $\\Delta\\tau^{c}$, for\narbitrary loading orientations and find that plastic deformation generically\ninduces material polarization, i.e., a forward-backward asymmetry in the\n$\\Delta\\tau^{c}$ distribution. In steady plastic flow, local packings are on\naverage closer to forward (rather than backward) instabilities, due to the\nstress-induced bias of barriers. However, presumably due to mechanical noise, a\nsignificant fraction of zones lie close to reverse (backward) yielding, as the\ndistribution of $\\Delta\\tau^{c}$ for reverse shearing extends quasilinearly\ndown to zero local residual strength. By constructing an elementary model of\nthe early plastic response, we then show that unloading causes reverse\nplasticity of a growing amplitude, i.e., reverse softening, while it shifts\naway forward-yielding barriers. This result in an inversion of polarization in\nthe low-$\\Delta\\tau^{c}$ region and, consequently, in the Bauschinger effect.\nThis scenario is quite generic, which explains the pervasiveness of the effect."
    },
    {
        "anchor": "Unveiling AC electronic properties at ferroelectric domain walls: Ferroelectric domain walls exhibit a range of interesting electrical\nproperties and are now widely recognized as functional two-dimensional systems\nfor the development of next-generation nanoelectronics. A major achievement in\nthe field was the development of a fundamental framework that explains the\nemergence of enhanced electronic direct-current (DC) conduction at the domain\nwalls. In this Review, we discuss the much less explored behavior of\nferroelectric domain walls under applied alternating-current (AC) voltages. We\nprovide an overview of the recent advances in the nanoscale characterization\nthat allow for resolving the dynamic responses of individual domain walls to AC\nfields. In addition, different examples are presented, showing the unusual AC\nelectronic properties that arise at neutral and charged domain walls in the\nkilo- to gigahertz regime. We conclude with a discussion about the future\ndirection of the field and novel application opportunities, expanding\ndomain-wall based nanoelectronics into the realm of AC technologies.",
        "positive": "${\\it Ab\\ initio}$ thermodynamic properties of certain compounds in\n  Nd-Fe-B system: In this work, we report the results of \\emph{ab initio} calculations of\nthermochemical properties of several compounds in the Fe-Nd, B-Nd and B-Fe-Nd\nsystems. We have performed DFT+U calculations to compute the enthalpy of\nformation of the compounds NdB$_6$, NdB$_4$, Nd$_2$B$_5$, Nd$_2$Fe$_{17}$ and\nNd$_5$Fe$_2$B$_6$. It was found that the values obtained with an effective\nHubbard $U$ correction have better agreement with the experimental data. We\nhave also computed the vibrational contribution to the heat capacity ($C_p$) of\nthe compounds as a function of temperature was computed using the quasharmonic\napproximation. For most of the compounds these properties have not been\nexperimentally determined until now. Hence, the computed \\emph{ab initio}\nthermodynamic properties will serve as useful input for the Gibbs energy model\nparameter assessment using the CALPHAD method."
    },
    {
        "anchor": "Hydride growth mechanism in Zircaloy-4: investigation of the\n  partitioning of alloying elements: The long-term safety of water-based nuclear reactors relies in part on the\nreliability of zirconium-based nuclear fuel. Yet the progressive ingress of\nhydrogen during service makes zirconium alloys subject to delayed hydride\ncracking. Here, we use a combination of electron back-scattered diffraction and\natom probe tomography to investigate specific microstructural features from the\nas-received sample and in the blocky-alpha microstructure, before and after\nelectrochemical charging with hydrogen or deuterium followed by a low\ntemperature heat treatment at 400C for 5 hours followed by furnace cooling at a\nrate of 0. 5C per min. Specimens for atom probe were prepared at cryogenic\ntemperature to avoid the formation of spurious hydrides. We report on the\ncompositional evolution of grains and grain boundaries over the course of the\nsample's thermal history, as well as the ways the growth of the hydrides\nmodifies locally the composition and the structure of the alloy. We observe a\nsignificant amount of deuterium left in the matrix, even after the slow cooling\nand growth of the hydrides. Stacking faults form ahead of the growth front and\nSn segregates at the hydride-matrix interface and on these faults. We propose\nthat this segregation may facilitate further growth of the hydride. Our\nsystematic investigation enables us discuss how the solute distribution affects\nthe evolution of the alloy's properties during its service lifetime.",
        "positive": "Self-Assembled Graphene Plasmon Resonators: The ability to fabricate dense small features over a large area is important\nfor graphene plasmonics. We present the first self-assembled graphene plasmonic\nresonators operating in the mid-IR. The resonators are 35 nm in diameter with\n20 nm spacing and cover a centimeter sized area. The resonators exhibit a very\nbroad resonance. We fit our data using a drude model and combine it with SEM\ndata to investigate the contribution to broadening from our process. We find\nthat the self-assembly does not contribute significantly to the broadening\nobserved."
    },
    {
        "anchor": "MoS$_2$ 2D-polymorphs as a Li-/Na-ion batteries: 1T' vs 2H phases: In this study, we compare the performance of two phases of MoS$_2$\nmonolayers: 1T' and 2H, about their ability to adsorb lithium and sodium ions.\nEmploying the density functional theory and molecular dynamics, we include the\nion concentration to analyze the electronic structure, ion kinetics, and\nbattery performance. The pristine 2H-MoS$_2$ monolayer is the ground state.\nHowever, the charge transfer effects above a critical ion concentration yields\na stability change, where the 1T'-MoS$_2$ monolayer with adsorbed ions becomes\nmore stable than the 2H counterpart. The diffusion of ions onto the 1T'\nmonolayer is anisotropic, being more efficient at ion adsorption than the 2H\nphase. Finally, we calculate the open circuit voltage and specific capacity,\nconfirming that the 1T'-MoS$_2$ phase has great potential for developing\nlithium/sodium ion batteries.",
        "positive": "Covalent Adsorption of functional groups on [N]-carbophenes: Starting from the planar molecule 1,3,5-trihydroxybenzene, Du et al. reported\nsynthesizing one of a couple of possible 2D materials: graphenylene or\n3-carbophene. 3-carbophene is a member of a novel class of two-dimensional\ncovalent organic framework, [N]-carbophenes (carbophenes). Using a high\nthroughput method, we computed the formation energies and conduction properties\nof 3-, 4-, 5-, and 6-carbophenes with hydroxyl (OH), carbonyl (CO), nitro\n(NO$_2$), amine (NH$_2$), carboxyl (COOH) functional groups replacing hydrogen\nterminating agents. Five hundred and nine structures with randomly picked\nmotifs, with functionalizations from a single functional group per cell to\nfully functionalized were studied. Our results demonstrate a negatively sloped\nlinear relationship between the degree of functionalization and formation\nenergy when the type of functional group and type of carbophene are held\nconstant. The decrease in formation energy with functionalization makes Du's\nsynthesis of functionalized 3-carbophene more creditable. The type of\ncarbophene, type of functional group, and the degree of functionalization all\nplay a role in the band structure of the materials. For example, CO functional\ngroups may lead to a mid-gap state pinned to the Fermi level, whereas the other\nfunctional groups studied keep the semiconducting nature of pristine\ncarbophene. Thus, because carbonyl functional groups are often present in\ndefected carbon systems, care should be taken to limit the amount of oxygen in\ncarbophene devices where the band gap is important. Thus, this work strengthens\nthe hypothesis of Junkermeier et al.'s hypothesis that Du et al. synthesized\n3-carbophene and not graphenylene."
    },
    {
        "anchor": "Origins of the transformability of Nickel-Titanium shape memory alloys: The near equiatomic NiTi alloy is the most successful shape memory alloy by a\nlarge margin. It is widely and increasingly used in biomedical devices. Yet,\ndespite having a repeatable superelastic effect and excellent shape-memory,\nNiTi is very far from satisfying the conditions that characterize the most\nreversible phase transforming materials. Thus, the scientific reasons\nunderlying its vast success present an enigma. In this work, we perform\nrigorous mathematical derivation and accurate DFT calculation of transformation\nmechanisms to seek previously unrecognized twin-like defects that we term\ninvolution domains, and we observe them in real space in NiTi by the\naberration-corrected scanning transmission electron microscopy. Involution\ndomains lead to an additional 216 compatible interfaces between phases in NiTi,\nand we theorize that this feature contributes importantly to its reliability.\nThey are expected to arise in other transformations and to alter the\nconventional interpretation of the mechanism of the martensitic transformation.",
        "positive": "High-pressure phase relations in Zn2SiO4 system: A first-principles\n  study: In order to clarify phase relation of Zn2SiO4 system, first-principles DFT\ncalculations of 11 phases were conducted. We confirmed that phases III and IV\nare retrograde phases. Instead, Na2CrO4- and Ag2CrO4-structured phases are most\nlikely candidate structures for high-pressure phases of III and IV,\nrespectively. A transition of phase II to spinel found during optimization was\ndiscussed in relation to similar transition known for nitrides."
    },
    {
        "anchor": "A model of homogeneous semicoherent interphase boundary for heterophase\n  precipitates in substitution alloys under irradiation: The model of homogeneous semicoherent interphase boundary describes the\nprocesses of absorption and thermoactivated migration of irradiation-produced\ninequilibrium point defects at a semicoherent boundary between a heterophase\nprecipitate and a substitution solid solution. Within this model the kinetics\nof evolution of the sizes of precipitates of constant chemical composition\nunder irradiation is investigated. The results obtained are compared to the\nexperimental data [I. Monnet et al., J. Nucl. Mater. 335 (2004) 311] for the\nferritic ODS steel EM10+MgO under electron irradiation.",
        "positive": "Spontaneous Surface Collapse and Reconstruction in Antiferromagnetic\n  Topological Insulator MnBi$_2$Te$_4$: MnBi$_2$Te$_4$ is an antiferromagnetic topological insulator which stimulates\nintense interests due to the exotic quantum phenomena and promising device\napplications. Surface structure is a determinant factor to understand the novel\nmagnetic and topological behavior of MnBi2Te4, yet its precise atomic structure\nremains elusive. Here, we discovered a spontaneous surface collapse and\nreconstruction in few-layer MnBi2Te4 exfoliated under delicate protection.\nInstead of the ideal septuple-layer structure in the bulk, the collapsed\nsurface is shown to reconstruct as Mn-doped Bi$_2$Te$_3$ quintuple-layer and\nMn$_x$Bi$_y$Te double-layer with a clear van der Waals gap in between.\nCombining with first-principles calculations, such spontaneous surface collapse\nis attributed to the abundant intrinsic Mn-Bi antisite defects and tellurium\nvacancy in the exfoliated surface, which is further supported by in-situ\nannealing and electron irradiation experiments. Our results shed light on the\nunderstanding of the intricate surface-bulk correspondence of MnBi$_2$Te$_4$,\nand provide insightful perspective of the surface-related quantum measurements\nin MnBi$_2$Te$_4$ few-layer devices."
    },
    {
        "anchor": "Phase-field modeling of non-isothermal grain coalescence in the\n  unconventional sintering techniques: A thermodynamically consistent phase-field model is developed to study the\nnon-isothermal grain coalescence during the sintering process, with a potential\napplication to the simulation in unconventional sintering techniques, e.g.\nspark plasma sintering, field-assisted sintering, and selective laser\nsintering, where non-equilibrium and high temperature gradient exist. In the\nmodel, order parameters are adopted to represent the bulk and atmosphere/pore\nregion, as well as the crystallographic orientations. Based on the entropy\nanalysis, the temperature-dependent free energy density is developed, which\nincludes contributions from the internal energy (induced by the change of\ntemperature and order parameters) and the order parameter related\nconfigurational entropy. The temperature-dependent model parameters are\ndetermined by using the experimental data of surface and grain boundary\nenergies and interface width. From laws of thermodynamics, the kinetics for the\norder parameters and the order-parameter-coupled heat transfer are derived. The\nmodel is numerically implemented by the finite element method. Grain\ncoalescence from two identical particles shows that non-isothermal condition\nleads to the unsymmetric morphology and curved grain boundary due to the\ngradients of on-site surface and grain-boundary energies induced by the local\ntemperature inhomogeneity. More simulations on the non-isothermal grain\ncoalescence from two non-identical and multiple particles present the temporal\nevolution of grain shrinkage/growth, neck growth, and porosity, demonstrating\nthe capability and versatility of the model. It is anticipated that the work\ncould provide a contribution to the research community of unconventional\nsintering techniques that can be used to model the non-isothermal related\nmicrostructural features.",
        "positive": "A Systematic Approach to Generating Accurate Neural Network Potentials:\n  the Case of Carbon: Availability of affordable and widely applicable interatomic potentials is\nthe key needed to unlock the riches of modern materials modelling. Artificial\nneural network based approaches for generating potentials are promising;\nhowever neural network training requires large amounts of data, sampled\nadequately from an often unknown potential energy surface. Here we propose a\nself-consistent approach that is based on crystal structure prediction\nformalism and is guided by unsupervised data analysis, to construct an\naccurate, inexpensive and transferable artificial neural network potential.\nUsing this approach, we construct an interatomic potential for Carbon and\ndemonstrate its ability to reproduce first principles results on elastic and\nvibrational properties for diamond, graphite and graphene, as well as energy\nordering and structural properties of a wide range of crystalline and amorphous\nphases."
    },
    {
        "anchor": "Epitaxial growth of Bi$_2$Pt$_2$O$_7$ pyrochlore: Certain pyrochlore oxides are among the best oxygen catalysts in alkaline\nmedia. Hence, exploring epitaxial films of these materials is of great\nfundamental and technological interest. Unfortunately, direct film growth of\none of the most promising pyrochlores, Bi$_2$Pt$_2$O$_7$, has not yet been\nachieved, owing to the difficulty of oxidizing platinum metal in the precursor\nmaterial to Pt$^{4+}$. In this work, in order to induce oxidation of the\nplatinum, we annealed pulsed laser deposited films consisting of epitaxial\n$\\delta$-Bi$_2$O$_3$ and co-deposited, comparatively disordered platinum. We\npresent synchrotron x-ray diffraction results that show the annealed films are\nthe first epitaxial crystals of Bi$_2$Pt$_2$O$_7$. We also visualized the\npyrochlore structure by scanning transmission electron microscopy, and observed\nordered cation vacancies in a bismuth-rich film but not in a platinum-rich\nfilm. The similarity between the $\\delta$-Bi$_2$O$_3$ and Bi$_2$Pt$_2$O$_7$\nstructures appears to facilitate the pyrochlore formation. These results\nconstitute a new approach for synthesis of novel pyrochlore thin film oxygen\ncatalysts.",
        "positive": "Antiferromagnetic Topological Insulator MnBi2Te4: Synthesis and Magnetic\n  properties: Recently, MnBi2Te4 has been discovered as the first intrinsic\nantiferromagnetic topological insulator (AFM TI), and will become a promising\nmaterial to discover exotic topological quantum phenomena. In this work, we\nhave realized the successful synthesis of high-quality MnBi2Te4 single crystals\nby solid-state reactions. The as-grown MnBi2Te4 single crystal exhibits a van\nder Waals layered structure, which is composed of septuple Te-Bi-Te-Mn-Te-Bi-Te\nsequences as determined by powder X-ray diffraction (PXRD) and high-resolution\nhigh-angle annular dark field scanning transmission electron microscopy\n(HAADF-STEM). The magnetic order below 25 K as a consequence of A-type\nantiferromagnetic interaction between Mn layers in the MnBi2Te4 crystal\nsuggests the unique interplay between antiferromagnetism and topological\nquantum states. The transport measurements of MnBi2Te4 single crystals further\nconfirm its magnetic transition. Moreover, the unstable surface of MnBi2Te4,\nwhich is found to be easily oxidized in air, deserves attention for onging\nresearch on few-layer samples. This study on the first AFM TI of MnBi2Te4 will\nguide the future research on other potential candidates in the MBixTey family\n(M = Ni, V, Ti, etc.)."
    },
    {
        "anchor": "Exploring high thermal conductivity polymers via interpretable machine\n  learning with physical descriptors: The efficient and economical exploitation of polymers with high thermal\nconductivity is essential to solve the issue of heat dissipation in organic\ndevices. Currently, the experimental preparation of functional thermal\nconductivity polymers remains a trial and error process due to the\nmulti-degrees of freedom during the synthesis and characterization process. In\nthis work, we have proposed a high-throughput screening framework for polymer\nchains with high thermal conductivity via interpretable machine learning and\nphysical-feature engineering. The polymer thermal conductivity datasets for\ntraining were first collected by molecular dynamics simulation. Inspired by the\ndrug-like small molecule representation and molecular force field, 320 polymer\nmonomer descriptors were calculated and the 20 optimized descriptors with\nphysical meaning were extracted by hierarchical down-selection. All the machine\nlearning models achieve a prediction accuracy R2 greater than 0.80, which is\nsuperior to that of represented by traditional graph descriptors. Further, the\ncross-sectional area and dihedral stiffness descriptors were identified for\npositive/negative contribution to thermal conductivity, and 107 promising\npolymer structures with thermal conductivity greater than 20.00 W/mK were\nobtained. Mathematical formulas for predicting the polymer thermal conductivity\nwere also constructed by using symbolic regression. The high thermal\nconductivity polymer structures are mostly {\\pi}-conjugated, whose overlapping\np-orbitals enable easily to maintain strong chain stiffness and large group\nvelocities. The proposed data-driven framework should facilitate the\ntheoretical and experimental design of polymers with desirable properties.",
        "positive": "Rectification of radio frequency current in giant magnetoresistance spin\n  valve: We report on a highly efficient spin diode effect in an exchange-biased\nspin-valve giant magnetoresistance (GMR) strips. In such multilayer structures,\nsymmetry of the current distribution along the vertical direction is broken\nand, as a result, a non-compensated Oersted field acting on the magnetic free\nlayer appears. This field, in turn, is a driving force of magnetization\nprecessions. Due to the GMR effect, resistance of the strip oscillates\nfollowing the magnetization dynamics. This leads to rectification of the\napplied radio frequency current and induces a direct current voltage $V_{DC}$.\nWe present a theoretical description of this phenomenon and calculate the spin\ndiode signal, $V_{DC}$, as a function of frequency, external magnetic field,\nand angle at which the external field is applied. A satisfactory quantitative\nagreement between theoretical predictions and experimental data has been\nachieved. Finally, we show that the spin diode signal in GMR devices is\nsignificantly stronger than in the anisotropic magnetoresistance\npermalloy-based devices."
    },
    {
        "anchor": "Tunability of High-Dielectric-Constant Materials from First Principles: A first-principles method, based on density functional perturbation theory,\nis presented for computing the leading order tunability of\nhigh-dielectric-constant materials.",
        "positive": "The role of \u03b2-titanium ligaments in the deformation of dual phase\n  titanium alloys: Multiphase titanium alloys are critical materials in high value engineering\ncomponents, for instance in aero engines. Microstructural complexity is\nexploited through interface engineering during mechanical processing to realise\nsignificant improvements in fatigue and fracture resistance and strength. In\nthis work, we explore the role of select interfaces using in-situ\nmicromechanical testing with concurrent observations from high angular\nresolution electron backscatter diffraction (HR-EBSD). Our results are\nsupported with post mortem transmission electron microscopy (TEM). Using\nmicro-pillar compression, we performed in-depth analysis of the role of select\n{\\beta}-titanium (body centred cubic) ligaments which separate neighbouring\n{\\alpha}-titanium (hexagonal close packed) regions and inhibit the dislocation\nmotion and impact strength during mechanical deformation. These results shed\nlight on the strengthening mechanisms and those that can lead to strain\nlocalisation during fatigue and failure."
    },
    {
        "anchor": "Exchange bias in [Co2MnGe/Au],[Co2MnGe/Cr] and [Co2MnGe/Cu2MnAl]\n  multilayers: We report structural and magnetic properties of multilayers composed of thin\nlayers of the half metallic ferromagnetic Heusler compound Co2MnGe and layers\nof Au, Cr and the Heusler compound Cu2MnAl. The hysteresis loops measured at\nlow temperatures reveal the existence of an exchange bias field HEB in all of\nthese multilayers. For the [Co2MnGe/Au] multilayer system HEB is largest\nreaching up to 1 kOe at a temperature of 2 K. We characterize the exchange bias\nphenomenon in detail and show that it originates from a spin glass type of\nmagnetic order for a thin interlayer at the interfaces. We discuss the results\nin the light of different models proposed for the explanation of the exchange\nbias effect.",
        "positive": "Unusual compressibility in the negative-thermal-expansion material\n  ZrW2O8: The negative thermal expansion (NTE) compound ZrW2O8 has been well-studied\nbecause it remains cubic with a nearly constant, isotropic NTE coefficient over\na broad temperature range. However, its elastic constants seem just as strange\nas its volume because NTE makes temperature acts as positive pressure,\ndecreasing volume on warming and, unlike most materials, the\nthermally-compressed solid softens. Does ZrW2O8 also soften when pressure alone\nis applied? Using pulse-echo ultrasound in a hydrostatic SiC anvil cell, we\ndetermine the elastic tensor of monocrystalline ZrW2O8 near 300 K as a function\nof pressure. We indeed find an unusual decrease in bulk modulus with pressure.\nOur results are inconsistent with conventional lattice dynamics, but do show\nthat the thermodynamically-complete constrained-lattice model can relate NTE to\nelastic softening as increases in either temperature or pressure reduce volume,\nestablishing the predictive power of the model, and making it an important\nconcept in condensed-matter physics."
    },
    {
        "anchor": "Observation of the spin Seebeck effect in epitaxial Fe3O4 thin films: We report the first experimental observation of the spin Seebeck effect in\nmagnetite thin films. The signal observed at temperatures above the Verwey\ntransition is a contribution from both the anomalous Nernst (ANE) and spin\nSeebeck effects (SSE). The contribution from the ANE of the Fe3O4 layer to the\nSSE is found to be negligible due to the resistivity difference between Fe3O4\nand Pt layers. Below the Verwey transition the SSE is free from the ANE of the\nferromagnetic layer and it is also found to dominate over the ANE due to\nmagnetic proximity effect on the Pt layer.",
        "positive": "First-principles studies for structural transitions in ordered phase of\n  cubic approximant Cd6Ca: Recently low-temperature structural transition has been reported for complex\ncubic compounds Cd6M (M=Ca, Yb, Y, rare earth) and it is believed that the\ntransition is due to orientational ordering of an atomic shell in the\nicosahedral cluster in Cd6M. The first-principles electronic structure\ncalculations and structural relaxations are carried out to investigate\nstructures and orientational ordering of the innermost tetrahedral shell of the\nicosahedral cluster in Cd6Ca. The very short interatomic distances in the\nexperimental average structures are relaxed and the innermost tetrahedral shell\nof an almost regular shape is obtained. Three types of orientation for the\ntetrahedral shell and eight different combinations of them for the clusters at\na vertex and body-centre of a cubic cell are obtained. A possible model\ndescribing the orientational ordering at low temperatures or high pressures is\ndiscussed."
    },
    {
        "anchor": "Nonlinear screening of charges induced in graphene by metal contacts: To understand the band bending caused by metal contacts, we study the\npotential and charge density induced in graphene in response to contact with a\nmetal strip. We find that the screening is weak by comparison with a normal\nmetal as a consequence of the ultra-relativistic nature of the electron\nspectrum near the Fermi energy. The induced potential decays with the distance\nfrom the metal contact as x^{-1/2} and x^{-1} for undoped and doped graphene,\nrespectively, breaking its spatial homogeneity. In the contact region the metal\ncontact can give rise to the formation of a p-p', n-n', p-n junction (or with\nadditional gating or impurity doping, even a p-n-p' junction) that contributes\nto the overall resistance of the graphene sample, destroying its electron-hole\nsymmetry. Using the work functions of metal-covered graphene recently\ncalculated by Khomyakov et al. [Phys. Rev. B 79, 195425 (2009)] we predict the\nboundary potential and junction type for different metal contacts.",
        "positive": "Anisotropic magneto-thermal transport in Co$_2$MnGa thin films: Ferromagnetic Co$_2$MnGa has recently attracted significant attention due to\neffects related to non-trivial topology of its band structure, however a\nsystematic study of canonical magneto-galvanic transport effects is missing.\nFocusing on high quality thin films, here we systematically measure anisotropic\nmagnetoresistance (AMR) and its thermoelectric counterpart (AMTP). We model the\nAMR data by free energy minimisation within the Stoner-Wohlfarth formalism and\nconclude that both crystalline and non-crystalline components of this\nmagneto-transport phenomenon are present in Co$_2$MnGa. Unlike the AMR which is\nsmall in relative terms, the AMTP is large due to a change of sign of the\nSeebeck coefficient as a function of temperature. This fact is discussed in the\ncontext of the Mott rule and further analysis of AMTP components is presented."
    },
    {
        "anchor": "Role of electronic localization in the phosphorescence of iridium\n  sensitizing dyes: In this work we present a systematic study of three representative iridium\ndyes, namely, Ir(ppy)3, FIrpic and PQIr, which are commonly used as sensitizers\nin organic optoelectronic devices. We show that electronic correlations play a\ncrucial role in determining the excited-state energies in these systems, due to\nlocalization of electrons on Ir d orbitals. Electronic localization is captured\nby employing hybrid functionals within time-dependent density-functional theory\n(TDDFT) and with Hubbard-model corrections within the delta-SCF approach. The\nperformance of both methods are studied comparatively and shown to be in good\nagreement with experiment. The Hubbard-corrected functionals provide further\ninsight into the localization of electrons and on the charge-transfer character\nof excited-states. The gained insight allows us to comment on envisioned\nfunctionalization strategies to improve the performance of these systems.\nComplementary discussions on the delta-SCF method are also presented in order\nto fill some of the gaps in the literature.",
        "positive": "Growth of Diamond Films from Tequila: Diamond thin films were growth using Tequila as precursor by Pulsed Liquid\nInjection Chemical Vapor Deposition (PLI-CVD) onto both silicon (100) and\nstainless steel 304 at 850 C. The diamond films were characterized by Scanning\nElectron Microscopy (SEM) and Raman spectroscopy. The spherical crystallites\n(100 to 400 nm) show the characteristic 1332 cm-1 Raman band of diamond."
    },
    {
        "anchor": "Acetylene-Accelerated Alcohol Catalytic CVD Growth of Vertically Aligned\n  Single-Walled Carbon Nanotubes: Addition of only 1% of acetylene into ethanol was found to enhance the growth\nrate of singlewalled carbon nanotubes (SWNTs) by up to ten times. Since\nacetylene is a byproduct of the thermal decomposition of ethanol, this suggests\nan alternative fast reaction pathway to the formation of SWNTs from ethanol via\nbyproducts of decomposition. This accelerated growth, however, only occurred in\nthe presence of ethanol, whereas pure acetylene at the same partial pressure\nresulted in negligible growth and quickly deactivated the catalyst. The dormant\ncatalyst could be revived by reintroduction of ethanol, indicating that\ncatalyst deactivation is divided into reversible and irreversible stages.",
        "positive": "Photoelectrochemical and photocatalytic properties of N + S co-doped\n  TiO2 nanotube array films under visible light irradiation: In this paper, we report on the co-doping nitrogen and sulfur has been\nachieved in the TiO2 nanotube array films by treatment with thiourea and\ncalcination under vacuum at 500 {\\deg}C for 3 h. The samples were characterized\nby scanning electron microscopy, X-ray diffraction (XRD), X-ray photoelectron\nspectroscopy (XPS) and ultraviolet-visible diffuse reflectance spectroscopy.\nXPS spectra revealed that N might coexist in the forms of NTiO and NOTi, S was\nincorporated into the lattice of TiO2 through substituting oxygen atoms in the\nN + S co-doped TiO2 nanotube array films. XRD patterns indicated that improved\ncrystallinity was obtained for N + S co-doped TiO2 nanotube arrays as compared\nto that of undoped TiO2 nanotube arrays. In photoelectrochemical measurements,\nthe photocurrent of N + S co-doped TiO2 nanotube array films was greatly\nenhanced compared to that of undoped samples under visible light irradiation.\nAnd the photocatalytic activities of the samples were evaluated on the removal\nof methylene blue under visible light irradiation. The N + S co-doped TiO2\nnanotube array films showed a better photocatalytic activity than the undoped\nsample due to the N, S doping.\n  Keywords: Nanostructures; Oxide; Thin films; Electrochemical properties"
    },
    {
        "anchor": "Magnetoresistance and Scaling Laws in Type-II Weyl Semimetal WP_2: Topological materials with extremely large magnetoresistance exhibit a\nprognostic feature of resistivity turn-on behaviour. This occurs when the\ntemperature dependence of resistivity changes from metallic to semiconducting\ncharacteristics on application of external magnetic field above a threshold\nvalue. Here, we study the magneto-transport properties of type-II Weyl\nSemimetal WP2. We find that semi-classical theories of magnetoresistance are\nconsistent with our data without the need to invoke topological surface states.\nOur findings in this work provides an alternative basis to understand the\ntemperature dependence of magnetoresistance in topological materials.",
        "positive": "Temperature dependence of the optical phonon reflection band in GaP: We explore the effect of temperatures between 80 and 720 K on the energy and\nlinewidth of zone-center transverse (TO) and longitudinal (LO) optical phonons\nin bulk gallium phosphide (GaP) using Fourier transform infrared ellipsometry\nfrom 0.03 to 0.60 eV. We extract the optical phonon parameters of GaP by\nfitting the ellipsometric angles with the Lowndes-Gervais model, which applies\ntwo different broadening parameters to the TO and LO phonons. In GaP, the\ntwo-phonon density of states is larger for the decay of TO phonons than for LO\nphonons. Therefore, we observed a larger TO phonon broadening (compared to the\nLO phonon) and an asymmetric reststrahlen line shape. This would lead to a\nnegative imaginary part of the dielectric function just above the LO phonon\nenergy, but the addition of two-phonon absorption avoids this. We find a\ntemperature dependent redshift and broadening of TO and LO phonons with\nincreasing temperature due to thermal expansion and anharmonic phonon-phonon\nscattering, involving three and four phonon decay processes. We also\ninvestigate the temperature-dependence of the high-frequency dielectric\nconstant. Its variation is explained by thermal expansion and the temperature\ndependence of the Penn gap."
    },
    {
        "anchor": "Continuum model of strong light-matter coupling for molecular polaritons: Strong coupling between light and matter generates hybrid polaritons. We\npresent a continuum model that describes the polaritons by light and matter\ndensities of states (DOS) that only depend on the refractive index of the\nmaterial. This model is applied to molecular polaritons derived from molecules\nwith broad spectral absorption. While the photonic DOS has a complex spectral\ndistribution, the matter DOS is largely unmodified by strong coupling. We argue\nthat bright states cannot be partitioned from dark states, and instead the\nphotonic DOS is shared over a vast number of matter states.",
        "positive": "A Review on Flexural Mode of Graphene: Lattice Dynamics, Thermal\n  Conduction, Thermal Expansion, Elasticity, and Nanomechanical Resonance: Single-layer graphene is so flexible that its flexural mode (also called the\nZA mode, bending mode, or out-of-plane transverse acoustic mode) is important\nfor its thermal and mechanical properties. Accordingly, this review focuses on\nexploring the relationship between the flexural mode and thermal and mechanical\nproperties of graphene. We first survey the lattice dynamic properties of the\nflexural mode, where the rigid translational and rotational invariances play a\ncrucial role. After that, we outline contributions from the flexural mode in\nfour different physical properties or phenomena of graphene -- its thermal\nconductivity, thermal expansion, Young's modulus, and nanomechanical resonance.\nWe explain how graphene's superior thermal conductivity is mainly due to its\nthree acoustic phonon modes at room temperature, including the flexural mode.\nIts coefficient of thermal expansion is negative in a wide temperature range\nresulting from the particular vibration morphology of the flexural mode. We\nthen describe how the Young's modulus of graphene can be extracted from its\nthermal fluctuations, which are dominated by the flexural mode. Finally, we\ndiscuss the effects of the flexural mode on graphene nanomechanical resonators,\nwhile also discussing how the essential properties of the resonators, including\nmass sensitivity and quality factor, can be enhanced."
    },
    {
        "anchor": "Absence of stable atomic structure in fluorinated graphene: Based on the results of first-principles calculations we demonstrate that\nsignificant distortion of graphene sheets caused by adsorption of fluorine\natoms leads to the formation of metastable patterns for which the next step of\nfluorination is considerably less energetically favorable. Existence of these\nstable patterns oriented along the armchair direction makes possible the\nsynthesis of various CFx structures. The combination of strong distortion of\nthe nonfluorinated graphene sheet with the doping caused by the polar nature of\nC-F bonds reduces the energy cost of migration and the energy of migration\nbarriers, making possible the migration of fluorine atoms on the graphene\nsurface as well as transformation of the shapes of fluorinated areas. The\ndecreasing energy cost of migration with increasing fluorine content also leads\nto increasing numbers of single fluorine adatoms, which could be the source of\nmagnetic moments.",
        "positive": "On the Allowable or Forbidden Nature of Vapor-Deposited Glasses: Vapor deposition can yield glasses that are more stable than those obtained\nby the traditional melt-quenching route. However, it remains unclear whether\nvapor-deposited glasses are \"allowable\" or \"forbidden,\" that is, if they are\nequivalent to glasses formed by cooling extremely slowly a liquid or if they\ndiffer in nature from melt-quenched glasses. Here, based on reactive molecular\ndynamics simulation (MD) of silica glasses, we demonstrate that the allowable\nor forbidden nature of vapor-deposited glasses depends on the temperature of\nthe substrate and, in turn, is found to be encoded in their medium-range order\nstructure."
    },
    {
        "anchor": "Magnetic Compton profile in non-magnetic ferroelectrics: Magnetic Compton scattering is an established tool for probing magnetism in\nferromagnetic or ferrimagnetic materials with a net spin polarization. Here we\nshow that, counterintuitively, {\\it non-magnetic} systems can also have a\nnon-zero magnetic Compton profile, provided that space-inversion symmetry is\nbroken. The magnetic Compton profile is antisymmetric in momentum and, if the\ninversion symmetry is broken by an electric-field switchable ferroelectric\ndistortion, can be reversed using an electric field. We show that the\nunderlying physics of the magnetic Compton profile and its electrical control\nare conveniently described in terms of $k$-space magnetoelectric multipoles,\nwhich are reciprocal to the real-space charge dipoles associated with the\nbroken inversion symmetry. Using the prototypical ferroelectric lead titanate,\nPbTiO$_3$, as an example, we show that the ferroelectric polarization\nintroduces a spin asymmetry in momentum space that corresponds to a pure\n$k$-space magnetoelectric toroidal moment. This in turn manifests in an\nantisymmetric magnetic Compton profile which can be reversed using an electric\nfield. Our work suggests an experimental route to directly measuring and tuning\nhidden $k$-space magnetoelectric multipoles via their magnetic Compton profile.",
        "positive": "Modeling of random bimodal structures of composites (application to\n  solid propellants): I. Simulation of random packs: We consider a composite medium, which consists of a homogeneous matrix\ncontaining a statistically homogeneous set of multimodal spherical inclusions.\nThis model is used to represent the morphology of heterogeneous solid\npropellants (HSP) that are widely used in the rocket industry. The\nLubachevsky-Stillinger algorithm is used to generate morphological models of\nHSP with large polydisperse packs of spherical inclusions. We modify the\nalgorithm by proposing a random shaking procedure that leads to the\nstabilization of a statistical distribution of the simulated structure that is\nhomogeneous, highly mixed, and protocol independent (in sense that the\nstatistical parameters estimated do not depend on the basic simulation\nalgorithm). Increasing the number of shaking has a twofold effect. First, the\nsystem becomes more homogeneous and well-mixed. Second, the stochastic\nfluctuations of statistical parameters (such as e.g. radial distribution\nfunction, RDF), estimated by averaging of these structures, tend to diminish."
    },
    {
        "anchor": "3D Microstructural and Strain Evolution During the Early Stages of\n  Tensile Deformation: Dislocation patterning and self-organization during plastic deformation are\nassociated with work hardening, but the exact mechanisms remain elusive. This\nis partly because studies of the structure and local strain during the initial\nstages of plastic deformation has been a challenge. Here we use Dark Field\nX-ray Microscopy to generate 3D maps of embedded $350 \\times 900 \\times 72\n\\,\\mu\\mathrm{m}^3$ volumes within three pure Al single crystals, all oriented\nfor double slip on the primary and conjugate slip systems. These were tensile\ndeformed by 0.6$\\%$, 1.7$\\%$ and 3.6$\\%$, respectively. Orientation maps\nrevealed the existence of two distinct types of planar dislocation boundaries\nboth at 0.6$\\%$ and 1.7$\\%$ but no systematic patterning. At 3.6$\\%$, these\nboundaries have evolved into a well-defined checkerboard pattern,\ncharacteristic of Geometrically Necessary Boundaries, GNBs. The GNB spacing is\n$\\approx$ 14 $\\mu$m and the misorientation $\\approx$ 0.2{\\deg}, in fair\nagreement with those at higher strains. By contrast to the sharp boundaries\nobserved at higher strains, the boundaries are associated with a sinusoidal\norientation gradient. Maps of the elastic strain along the (111) direction\nexhibit fluctuations of $\\pm 0.0002 $ with an average domain size of 3 $\\mu$m.",
        "positive": "Trilinear coupling driven ferroelectricity in HfO$_2$: Ferroelectricity in hafnia is often regarded as a breakthrough discovery in\nferroelectrics, potentially able to revolutionize the whole field. Despite\nincreasing interests, a comprehensive understanding of the many factors driving\nthe ferroelectric stabilization is still lacking. We here address the phase\ntransition in terms of a Landau-theory-based approach, by analyzing\nsymmetry-allowed distortions connecting the high-symmetry paraelectric\ntetragonal phase to the low-symmetry polar orthorhombic phase. By means of\nfirst-principles simulations, we find that the $\\Gamma_{3-}$ polar mode is only\nweakly unstable, whereas the other two symmetry-allowed distortions, non-polar\nY$_{2+}$ and anti-polar Y$_{4-}$ are hard modes. None of the modes, taken alone\nor combined with one other mode, is able to drive the transition: the key\nfactor in stabilizing the polar phase is identified as the strong trilinear\ncoupling among the three modes. Furthermore, the experimentally acknowledged\nimportance of substrate-induced effects in the growth of HfO$_2$ ferroelectric\nthin films, along with the lack of a clear order parameter in the transition,\nsuggested the extension of our analysis to strain effects. Our findings suggest\na complex behaviour of the Y$_{2+}$ mode, which become unstable under certain\nstrain conditions and an overall unstable behaviour for the $\\Gamma_{3-}$ polar\nmode for all the strain states. A robust result emerges from our analysis:\nindependently of the different applied strain (compressive or tensile, applied\nalong orthorhombic axes), the need of a simultaneous excitation of the three\ncoupled modes remain unaltered. Finally, when applied to mimic experimental\ngrowth conditions under strain, our analysis show a further stabilization of\nthe ferroelectric phase with respect to the unstrained case, in agreeement with\nexperimental findings."
    },
    {
        "anchor": "A Molecular Approach for Engineering Interfacial Interactions in\n  Magnetic-Topological Insulator Heterostructures: Controlling interfacial interactions in magnetic/topological insulator\nheterostructures is a major challenge for the emergence of novel spin-dependent\nelectronic phenomena. As for any rational design of heterostructures that rely\non proximity effects, one should ideally retain the overall properties of each\ncomponent while tuning interactions at the interface. However, in most\ninorganic interfaces interactions are too strong, consequently perturbing, and\neven quenching, both the magnetic moment and the topological surface states at\neach side of the interface. Here we show that these properties can be preserved\nby using ligand chemistry to tune the interaction of magnetic ions with the\nsurface states. By depositing Co-based porphyrin and phthalocyanine monolayers\non the surface of Bi$_2$Te$_3$ thin films, robust interfaces are formed that\npreserve undoped topological surface states as well as the pristine magnetic\nmoment of the divalent Co ions. The selected ligands allow us to tune the\ninterfacial hybridization within this weak interaction regime. These results,\nwhich are in stark contrast with the observed suppression of the surface state\nat the first quintuple layer of Bi$_2$Se$_3$ induced by the interaction with Co\nphthalocyanines, demonstrate the capability of planar metal-organic molecules\nto span interactions from the strong to the weak limit.",
        "positive": "Ab-initio insights into the elastic, bonding, phonon, optoelectronic and\n  thermophysical properties of SnTaS2: SnTaS2 is a recently discovered layered semimetal exhibiting type-II low\ntransition temperature superconductivity. Except some superconductivity related\nparameters, most of the physical properties, namely, elastic, mechanical,\nbonding, phonon dispersion, acoustic, thermophysical, and optical properties of\nSnTaS2 are unexplored till now. In this study, we have investigated these\nhitherto unexplored properties of SnTaS2 for the first time employing density\nfunctional theory (DFT) based first-principles method. SnTaS2 is a mechanically\nstable, elastically anisotropic compound with strongly layered feature. The\nbond hardness and Vickers hardness have been calculated. The material under\nstudy is ductile, soft and highly machinable. The chemical bonding feature has\nmixed character with significant contribution coming from the ionic channel.\nPhonon dispersion curves disclose dynamical stability. Electronic band\nstructure calculations show simple metallic character. The Fermi surface\nconsists of both electron-like and hole-like sheets with varying degrees of\ndispersion. The low energy (including visible part of the spectrum) refractive\nindex of SnTaS2 is high. The reflectivity is fairly nonselective over a wide\nrange of photon energy and the absorption coefficient is large in the mid\nultraviolet region. The Debye temperature and thermal conductivity of SnTaS2\nare low. The electron-phonon coupling constant has been calculated. The\ncompound under study possesses optical anisotropy with respect to the\npolarization direction of the incident electric field."
    },
    {
        "anchor": "Structural instability and charge modulations in the Kagome\n  superconductor $A$V$_3$Sb$_5$: Recently, both charge density wave (CDW) and superconductivity have been\nobserved in Kagome compounds $A$V$_3$Sb$_5$. However, the nature of CDW that\nresults in many novel charge modulations is still under hot debate.\n  By means of the first-principles calculations, we discover two kinds of CDW\nstates, the trimerized and hexamerized 2$\\times$2 phase and dimerized\n4$\\times$1 phase existing in $A$V$_3$Sb$_5$.\n  Our phonon excitation spectrum and electronic Lindhard function calculations\nreveal that the most intensive structural instability in $A$V$_3$Sb$_5$\noriginates from a combined in-plane vibration mode of V atoms through the\nelectron-phonon coupling, rather than the Fermi surface nesting effect.\n  Crucially, a metastable 4$\\times$1 phase with V-V dimer pattern and twofold\nsymmetric bowtie shaped charge modulation is revealed in CsV$_3$Sb$_5$,\nimplying that both dimerization and trimerization exist in the V Kagome layers.\n  These results provide essential understanding of CDW instability and new\nthoughts for the novel charge modulation patterns.",
        "positive": "A high temperature W$_2$B cermet for compact neutron shielding: We have developed a new material for neutron shielding applications where\nspace is restricted. W$_2$B is an excellent attenuator of neutrons and\ngamma-rays, due to the combined gamma attenuation of W and neutron absorption\nof B. However, its low fracture toughness (~3.5 MPa$\\cdot$m$^{0.5}$) and high\nmelting point (2670 {\\deg}C) prevent the fabrication of large fully-dense\nmonolithic parts with adequate mechanical properties. Here we meet these\nchallenges by combining W$_2$B with a minor fraction (43 vol.%) of metallic W.\nThe material was produced by reaction sintering W and BN powders. The\nmechanical properties under flexural and compressive loading were determined up\nto 1900 {\\deg}C. The presence of the ductile metallic W phase enabled a peak\nflexural strength of ~950 MPa at 1100 {\\deg}C, which is a factor of 2-3 higher\nthan typical monolithic transition-metal borides. Its ductile-brittle\ntransition temperature of ~1000 {\\deg}C is typical of W-based composites, which\nis surprising as the W phase was the minor constituent and did not appear to\nform a fully continuous network. Compression tests showed hardening below ~1500\n{\\deg}C and significant elongation of the phase domains, which suggest that by\nforging or rolling, further improvements in ductility may be possible."
    },
    {
        "anchor": "N-functionalized Ti2C MXene as high-performance adsorbent for strontium\n  ions: a first-principles study: Radionuclides sequestration through adsorption technology has attracted much\nattention due to its unique characters such as high removal efficiency, low\ncost, and ease of operation. In this work, the interaction mechanism of\nN-functionalized Ti2C MXene (Ti2CN2) as a potential adsorbent for the removal\nof strontium ions is investigated by using first principles method. Our results\nshow that surface N atoms are connected to Sr ions by a robust chemical N-Sr\nbond, which provides a stronger interaction and greater capacity (1.291g g-1)\nof Sr ion adsorption on Ti2CN2 than Ti2C with other surficial groups O, F and\nOH. Furthermore, the thermal stability of the adsorption structure of Sr on\nTi2CN2 with full layer coverage at room temperature is verified by using ab\ninitio molecular dynamics simulations. Our results are expected to provide a\nnew perspective for the design of MXene materials as adsorbent for\nradionuclide.",
        "positive": "Active learning based generative design for the discovery of wide\n  bandgap materials: Active learning has been increasingly applied to screening functional\nmaterials from existing materials databases with desired properties. However,\nthe number of known materials deposited in the popular materials databases such\nas ICSD and Materials Project is extremely limited and consists of just a tiny\nportion of the vast chemical design space. Herein we present an active\ngenerative inverse design method that combines active learning with a deep\nvariational autoencoder neural network and a generative adversarial deep neural\nnetwork model to discover new materials with a target property in the whole\nchemical design space. The application of this method has allowed us to\ndiscover new thermodynamically stable materials with high band gap (SrYF$_5$)\nand semiconductors with specified band gap ranges (SrClF$_3$, CaClF$_5$,\nYCl$_3$, SrC$_2$F$_3$, AlSCl, As$_2$O$_3$), all of which are verified by the\nfirst principle DFT calculations. Our experiments show that while active\nlearning itself may sample chemically infeasible candidates, these samples help\nto train effective screening models for filtering out materials with desired\nproperties from the hypothetical materials created by the generative model. The\nexperiments show the effectiveness of our active generative inverse design\napproach."
    },
    {
        "anchor": "Direct measurement of the three dimensional magnetization vector\n  trajectory in GaMnAs by a magneto-optical pump-and-probe method: We report on a quantitative experimental determination of the\nthree-dimensional magnetization vector trajectory in GaMnAs by means of the\nstatic and time-resolved pump-and-probe magneto-optical measurements. The\nexperiments are performed in a normal incidence geometry and the time evolution\nof the magnetization vector is obtained without any numerical modeling of\nmagnetization dynamics. Our experimental method utilizes different polarization\ndependences of the polar Kerr effect and magnetic linear dichroism to\ndisentangle the pump-induced out-of-plane and in-plane motions of\nmagnetization, respectively. We demonstrate that the method is sensitive enough\nto allow for the determination of small angle excitations of the magnetization\nin GaMnAs. The method is readily applicable to other magnetic materials with\nsufficiently strong circular and linear magneto-optical effects.",
        "positive": "Realization of multiple charge density waves in NbTe2 at the monolayer\n  limit: Abstract: Layered transition-metal dichalcogenides (TMDCs) down to the\nmonolayer (ML) limit provide a fertile platform for exploring charge-density\nwaves (CDWs). Though bulk NbTe2 is known to harbor a single axis 3*1 CDW\ncoexisting with non-trivial quantum properties, the scenario in the ML limit is\nstill experimentally unknown. In this study, we unveil the richness of the CDW\nphases in ML NbTe2, where not only the theoretically predicted 4*4 and 4*1\nphases, but also two unexpected sqrt(28)*sqrt(28) and sqrt(19)*sqrt(19) phases,\ncan be realized. For such a complex CDW system, we establish an exhaustive\ngrowth phase diagram via systematic efforts in the material synthesis and\nscanning tunneling microscope characterization. Moreover, we report that the\nenergetically stable phase is the larger scale order (sqrt(19)*sqrt(19)), which\nis surprisingly in contradiction to the prior prediction (4*4). These findings\nare confirmed using two different kinetic pathways, i.e., direct growth at\nproper growth temperatures (T), and low-T growth followed by high-T annealing.\nOur results provide a comprehensive diagram of the \"zoo\" of CDW orders in ML\n1T-NbTe2 for the first time and offer a new material platform for studying\nnovel quantum phases in the 2D limit."
    },
    {
        "anchor": "Theromelectricity in Graphene: Effects of a gap and magnetic fields: We calculate the thermopower of monolayer graphene in various circumstances.\nFirst we show that experiments on the thermopower of graphene can be understood\nquantitatively with a very simple model of screening in the semiclassical\nlimit. We can calculate the energy dependent scattering time for this model\nexactly. We then consider acoustic phonon scattering which might be the\noperative scattering mechanism in free standing films, and predict that the\nthermopower will be linear in any induced gap in the system. Further, the\nthermopower peaks at the same value of chemical potential (tunable by gate\nvoltage) independent of the gap. Finally, we show that in the semiclassical\napproximation, the thermopower in a magnetic field saturates at high field to a\nvalue which can be calculated exactly and is independent of the details of the\nscattering. This effect might be observable experimentally.",
        "positive": "Deformation and failure in nanomaterials via a data driven modelling\n  approach: A data driven computational model that accounts for more than two material\nstates has been presented in this work. Presented model can account for\nmultiple state variables, such as stresses, strains, strain rates and failure\nstress, as compared to previously reported models with two states. Model is\nused to perform deformation and failure simulations of carbon nanotubes and\ncarbon nanotube/epoxy nanocomposites. The model capability of capturing the\nstrain rate dependent deformation and failure has been demonstrated through\npredictions against uniaxial test data taken from literature. The predicted\nresults show a good agreement between data set taken from literature and\nsimulations."
    },
    {
        "anchor": "Unified decoupling scheme for exchange and anisotropy contributions and\n  temperature-dependent spectral properties of anisotropic spin systems: We compute the temperature-dependent spin-wave spectrum and the magnetization\nfor a spin system using the unified decoupling procedure for the high-order\nGreen's functions for the exchange coupling and anisotropy, both in the\nclassical and quantum case. Our approach allows us to establish a clear\ncrossover between quantum-mechanical and classical methods by developing the\nclassical analog of the quantum Green's function technique. The results are\ncompared with the classical spectral density method and numerical modeling\nbased on the stochastic Landau-Lifshitz equation and the Monte Carlo technique.\nAs far as the critical temperature is concerned, there is a full agreement\nbetween the classical Green's functions technique and the classical spectral\ndensity method. However, the former method turns out to be more straightforward\nand more convenient than the latter because it avoids any \\emph{a priori}\nassumptions about the system's spectral density. The temperature-dependent\nexchange stiffness as a function of magnetization is investigated within\ndifferent approaches.",
        "positive": "Single-crystalline gold microplates grown on substrates by\n  solution-phase synthesis: Chemically synthesized single-crystalline gold microplates have been\nattracting increasing interests because of their potential as high-quality gold\nfilms for nanotechnology. We present the growth of tens of nanometer thick and\ntens of micrometer large single-crystalline gold plates directly on solid\nsubstrates by solution-phase synthesis. Compared to microplates deposited on\nsubstrates from dispersion phase, substrate-grown plates exhibit significantly\nhigher quality by avoiding severe small-particle contamination and aggregation.\nSubstrate-grown gold plates also open new perspec-tives to study the growth\nmechanism via intermittent growth and observation cycles of a large number of\nindividual plates. Growth models are proposed to interpret the evolution of\nthickness, area and shape of plates. It is found that the plate surface remains\nsmooth after regrowth, implying the application of regrowth for producing giant\nplates as well as unique single-crystalline nano-structures."
    },
    {
        "anchor": "Misfit layer compounds: a platform for heavily-doped two-dimensional\n  transition metal dichalcogenides: Transition metal dichalcogenides (TMDs) display a rich variety of\ninstabilities such as spin and charge orders, Ising superconductivity and\ntopological properties. Their physical properties can be controlled by doping\nin electric double-layer field-effect transistors (FET). However, for the case\nof single layer NbSe$_2$, FET doping is limited to $\\approx 1\\times 10^{14}$\ncm$^{-2}$, while a somewhat larger charge injection can be obtained via\ndeposition of K atoms. Here, by performing ARPES, STM, quasiparticle\ninterference measurements, and first principles calculations we show that a\nmisfit compound formed by sandwiching NbSe$_2$ and LaSe layers behaves as a\nNbSe$_2$ single layer with a rigid doping of $0.55-0.6$ electrons per Nb atom\nor $\\approx 6\\times 10^{14}$ cm$^{-2}$. Due to this huge doping, the $3\\times3$\ncharge density wave is replaced by a $2\\times2$ order with very short coherence\nlength. As a tremendous number of different misfit compounds can be obtained by\nsandwiching TMDs layers with rock salt or other layers, our work paves the way\nto the exploration of heavily doped 2D TMDs over an unprecedented wide range of\ndoping.",
        "positive": "Features of the study of binder state near the filler particles in\n  elastomeric composites using an atomic-force microscope: Atomic force microscopy (AFM) is one of the most promising methods for\ninvestigating the structure of materials at the micro and nanoscale levels, as\nwell as their local physical-mechanical properties. The experimental data\nobtained with the help of AFM have a serious problem of assessing the accuracy\nand reliability. This is especially pronounced when studying materials with a\nstrong mechanical structural heterogeneity. Such materials include considered\nin this paper elastomers, filled with rigid dispersed particles. The article\npresents a technique for mathematical processing of such experimental data,\nwhich allows to significantly improve the accuracy of their interpretation. It\nis based on the use of three criteria for filtering and processing the\ninitially obtained experimental information. 1) The criterion of the \"relief of\nthe nanoscale\", which makes it possible to extract a relief with objects of low\ncurvature from the overall picture obtained. It is on it that the filler\nparticles protruding on the surface are clearly visible (usually covered with a\nthin film of elastomeric binder, known in the literature as bound rubber). 2)\n\"Adhesion deflection\" criterion, by means of which it is possible to isolate\nthe filler particles by changing the adhesion forces between the AFM probe and\nthe sample surface. 3) The criterion of \"indentational compliance\", designed to\ndetermine the location and stiffness of the filler particles. All these\ncriteria were used to decode the AFM scanning data of the surface of disperse\nfilled elastomeric composite. Optimal conditions for the application of each of\nthe criteria were determined from the analysis of the results obtained. Also,\nthe accuracy of the experimental results was estimated on the basis of a\ncomparison of the data obtained with the forward and reverse horizontal motion\nof the AFM probe when scanning the same surface area."
    },
    {
        "anchor": "EDA: EXAFS Data Analysis software package: The EXAFS data analysis software package EDA consists of a suite of programs\nrunning under Windows operating system environment and designed to perform all\nsteps of conventional EXAFS data analysis such as the extraction of the\nXANES/EXAFS parts of the x-ray absorption coefficient, the Fourier filtering,\nthe EXAFS fitting using the Gaussian and cumulant models. Besides, the package\nincludes two advanced approaches, which allow one to reconstruct the radial\ndistribution function (RDF) from EXAFS based on the regularization-like method\nand to calculate configurationalaveraged EXAFS using a set of atomic\nconfigurations obtained from molecular dynamics or Monte Carlo simulations.",
        "positive": "Magnetic properties of $(Fe_{1-x}Mn_x)_2AlB_2$ and the impact of\n  substitution on the magnetocaloric effect: In this work, we investigate the magnetic structures of\n$(Fe_{1-x}Mn_x)_2AlB_2$ solid-solution quaternaries in the $x = 0$ to $1$ range\nusing x-ray and neutron diffraction, magnetization measurements, and mean-field\ntheory calculations. While $Fe_2AlB_2$ and $Mn_2AlB_2$ are known to be\nferromagnetic (FM) and antiferromagnetic (AFM), respectively, herein we focused\non the magnetic structure of their solid solutions, which is not well\nunderstood. The FM ground state of $Fe_2AlB_2$ becomes a canted AFM at $x\n\\approx 0.2$, with a monotonically diminishing FM component until $x \\approx\n0.5$. The FM transition temperature ($T_C$) decreases linearly with increasing\n$x$. These changes in magnetic moments and structures are reflected in\nanomalous expansions of the lattice parameters, indicating a magnetoelastic\ncoupling. Lastly, the magnetocaloric properties of the solid solutions were\nexplored. For $x = 0.2$ the isothermal entropy change is smaller by 30% than it\nis for $Fe_2AlB_2$, while the relative cooling power is larger by 6%, due to\nbroadening of the temperature range of the transition."
    },
    {
        "anchor": "Calculating the trap density of states in organic field-effect\n  transistors from experiment: A comparison of different methods: The spectral density of localized states in the band gap of pentacene (trap\nDOS) was determined with a pentacene-based thin-film transistor from\nmeasurements of the temperature dependence and gate-voltage dependence of the\ncontact-corrected field-effect conductivity. Several analytical methods to\ncalculate the trap DOS from the measured data were used to clarify, if the\ndifferent methods lead to comparable results. We also used computer simulations\nto further test the results from the analytical methods. Most methods predict a\ntrap DOS close to the valence band edge that can be very well approximated by a\nsingle exponential function with a slope in the range of 50-60 meV and a trap\ndensity at the valence band edge of approx. 2x10E21 eV-1cm-3. Interestingly,\nthe trap DOS is always slightly steeper than exponential. An important finding\nis that the choice of the method to calculate the trap DOS from the measured\ndata can have a considerable effect on the final result. We identify two\nspecific simplifying assumptions that lead to significant errors in the trap\nDOS. The temperature-dependence of the band mobility should generally not be\nneglected. Moreover, the assumption of a constant effective accumulation layer\nthickness leads to a significant underestimation of the slope of the trap DOS.",
        "positive": "Machine-learning accelerated identification of exfoliable\n  two-dimensional materials: Two-dimensional (2D) materials have been a central focus of recent research\nbecause they host a variety of properties, making them attractive both for\nfundamental science and for applications. It is thus crucial to be able to\nidentify accurately and efficiently if bulk three-dimensional (3D) materials\nare formed by layers held together by a weak binding energy that, thus, can be\npotentially exfoliated into 2D materials. In this work, we develop a\nmachine-learning (ML) approach that, combined with a fast preliminary\ngeometrical screening, is able to efficiently identify potentially exfoliable\nmaterials. Starting from a combination of descriptors for crystal structures,\nwe work out a subset of them that are crucial for accurate predictions. Our\nfinal ML model, based on a random forest classifier, has a very high recall of\n98\\%. Using a SHapely Additive exPlanations (SHAP) analysis, we also provide an\nintuitive explanation of the five most important variables of the model.\nFinally, we compare the performance of our best ML model with a deep neural\nnetwork architecture using the same descriptors. To make our algorithms and\nmodels easily accessible, we publish an online tool on the Materials Cloud\nportal that only requires a bulk 3D crystal structure as input. Our tool thus\nprovides a practical yet straightforward approach to assess whether any 3D\ncompound can be exfoliated into 2D layers."
    },
    {
        "anchor": "Substrate-Controlled Magnetism: Fe nanowires on vicinal Cu surfaces: Here we present a novel approach to control magnetic interactions in\natomic-scale nanowires. Our ab initio calculations demonstrate the possibility\nto tune magnetic properties of Fe nanowires formed on vicinal Cu surfaces. Both\nintrawire and interwire magnetic exchange parameters are extracted from DFT\ncalculations. This study suggests that the effective interwire magnetic\nexchange parameters exhibit Ruderman--Kittel--Kasuya--Yosida-like (RKKY)\noscillations as a function of Fe interwire separation. The choice of vicinal Cu\nsurface offers possibilities for controlling the magnetic coupling.\nFurthermore, an anisotropic Heisenberg model was used in Monte Carlo\nsimulations to examine the stability of these magnetic configurations at finite\ntemperature. The predicted critical temperatures of the Fe nanowires on Cu(422)\nand Cu(533) surfaces are well-above room temperature.",
        "positive": "Origin and nature of killer defects in 3C-SiC for power electronic\n  applications by a multiscale atomistic approach: 3C-SiC epitaxially grown on Si displays a large wealth of extended defects.\nIn particular, single, double and triple stacking faults (SFs) are observed in\nseveral experiments to coexist. Overabundance of defects has so far limited the\nexploitation of 3C-SiC/Si for power electronics, in spite of its several ideal\nproperties (mainly in terms of wide gap, high breakdown fields and thermal\nproperties) and the possibility of a direct integration in the Si technology.\nHere we use a multiscale approach, based on both classical molecular dynamics\n(MD) simulations and first-principle calculations, to investigate in-depth the\norigin, nature and properties of most common 3C-SiC/Si(001) extended defects.\nOur MD simulations reveal a natural path for the formation of partial\ndislocation complexes terminating both double and triple SF's. MD results are\nused as input for superior DFT calculations, allowing us to better determine\nthe core structure and to investigate electronic properties. It turns out that\nthe partial dislocation complexes terminating double and triple SFs are\nresponsible for the introduction of electronic states significantly filling the\ngap. On the other hand, individual partial dislocations terminating single SFs\nonly induce states very close to the gap edge. We conclude that partial\ndislocation complexes, in particular the most abundant triple ones, are killer\ndefects in terms of favoring leakage currents. Suggestions coming from\ntheory/simulations for devising a strategy to lower their occurrence are\ndiscussed."
    },
    {
        "anchor": "Self-consistent potential correction for charged periodic systems: Supercell models are often used to calculate the electronic structure of\nlocal perturbations from the ideal periodicity in the bulk or on the surface of\na crystal or in wires. When the defect or adsorbent is charged, a jellium\ncounter charge is applied to maintain overall neutrality, but the interaction\nof the artificially repeated charges has to be corrected, both in the total\nenergy and in the one-electron eigenvalues and eigenstates. This becomes\nparamount in slab or wire calculations, where the jellium counter charge may\ninduce spurious states in the vacuum. We present here a self-consistent\npotential correction scheme and provide successful tests of it for bulk and\nslab calculations.",
        "positive": "Microwave Magneto-Chiral Effect in a Noncentro-symmetric Magnet CuB2O4: We have investigated microwave nonreciprocity in a noncentro-symmetric magnet\nCuB2O4. We simultaneously observed differently originated nonreciprocities; the\nclassical magnetic dipolar effect and the magneto-chiral (MCh) effect. By\nrotating magnetic field in a tetragonal plane, we clearly unveil qualitative\ndifference between them. The MCh effect signal reveals chiral transitions from\none enantiomer to the other via intermediate achiral state. We show\nmagnetoelectric effect plays an essential role for the emergence of microwave\nMCh effect."
    },
    {
        "anchor": "Two Dimensional Antiferromagnetic Chern Insulator NiRuCl6: Based on DFT and Berry curvature calculations, we predict that quantum\nanomalous hall effect (QAHE) can be realized in two dimensional\nanti-ferromagnetic (AFM) NiRuCl6 with zero net magnetic moment. By tuning\nspin-orbits coupling (SOC), we find that the topological properties of NiRuCl6\ncome from its energy band reversal. The results indicate that NiRuCl6 behaves\nas AFM Chern insulator and its spin-polarized electronic structure and strong\nspin-orbits coupling (SOC) are the origin of QAHE. Considering the\ncompatibility between AFM and insulator, AFM Chern insulator is more suitable\nto realize high temperature QAHE because generally Neel temperature of AFM\nsystems is more easily improved than Curie temperature of ferromagnetic (FM)\nsystems. Due to the different magnetic coupling mechanism between FM and AFM\nChern insulator, AFM Chern insulator provides a new way to archive high\ntemperature QAHE in experiments.",
        "positive": "A reduced model for shock and detonation waves. I. The inert case: We present a model of mesoparticles, very much in the Dissipative Particle\nDynamics spirit, in which a molecule is replaced by a particle with an internal\nthermodynamic degree of freedom (temperature or energy). The model is shown to\ngive quantitavely accurate results for the simulation of shock waves in a\ncrystalline polymer, and opens the way to a reduced model of detonation waves."
    },
    {
        "anchor": "Semi-Dirac Fermions in a Topological Metal: Topological semimetals with massless Dirac and Weyl fermions represent the\nforefront of quantum materials research. In two dimensions, a peculiar class of\nfermions that are massless in one direction and massive in the perpendicular\ndirection was predicted fifteen years ago. These highly exotic quasiparticles -\nthe semi-Dirac fermions - ignited intense theoretical interest but remain\nundetected. Using magneto-optical spectroscopy, we demonstrate the defining\nfeature of semi-Dirac fermions - B^(2/3) scaling of Landau levels - in a\nprototypical nodal-line metal ZrSiS. In topological metals, including ZrSiS,\nnodal-lines extend the band degeneracies from isolated points to lines, loops\nor even chains in the momentum space. With ab initio calculations and\ntheoretical modeling, we pinpoint the observed semi-Dirac spectrum to the\ncrossing points of nodal-lines in ZrSiS. Crossing nodal-lines exhibit a\ncontinuum absorption spectrum but with singularities that scale as B^(2/3) at\nthe crossing. Our work sheds light on the hidden quasiparticles emerging from\nthe intricate topology of crossing nodal-lines.",
        "positive": "Benchmarking van der Waals-treated DFT: The case of hexagonal boron\n  nitride and graphene on Ir(111): There is enormous recent interest in weak, van der Waals-type (vdW)\ninteractions due to their fundamental relevance for two-dimensional materials\nand the so-called vdW heterostructures. Tackling this problem using computer\nsimulation is very challenging due to the non-trivial, non-local nature of\nthese interactions. We benchmark different treatments of London dispersion\nforces within the density functional theory (DFT) framework on hexagonal boron\nnitride or graphene monolayers on Ir(111) by comparing the calculated\ngeometries to a comprehensive set of experimental data. The geometry of these\nsystems crucially depends on the interplay between vdW interactions and wave\nfunction hybridisation, making them excellent test cases for vdW-treated DFT.\nOur results show strong variations in the calculated atomic geometry. While\nsome of the approximations reproduce the experimental structure, this is rather\nbased on \\textit{a posteriori} comparison with the ``target results''. General\npredictive power in vdW-treated DFT is not achieved yet and might require new\napproaches."
    },
    {
        "anchor": "Superconductivity in Few-Layer Stanene: A single atomic slice of {\\alpha}-tin-stanene-has been predicted to host\nquantum spin Hall effect at room temperature, offering an ideal platform to\nstudy low-dimensional and topological physics. While recent research has\nintensively focused on monolayer stanene, the quantum size effect in few-layer\nstanene could profoundly change material properties, but remains unexplored. By\nexploring the layer degree of freedom, we unexpectedly discover\nsuperconductivity in few-layer stanene down to a bilayer grown on PbTe, while\nbulk {\\alpha}-tin is not superconductive. Through substrate engineering, we\nfurther realize a transition from a single-band to a two-band superconductor\nwith a doubling of the transition temperature. In-situ angle resolved\nphotoemission spectroscopy (ARPES) together with first-principles calculations\nelucidate the corresponding band structure. Interestingly, the theory also\nindicates the existence of a topologically nontrivial band. Our experimental\nfindings open up novel strategies for constructing two-dimensional topological\nsuperconductors.",
        "positive": "Spin-induced optical second harmonic generation in the centrosymmetric\n  magnetic semiconductors EuTe and EuSe: Spectroscopy of the centrosymmetric magnetic semiconductors EuTe and EuSe\nreveals spin-induced optical second harmonic generation (SHG) in the band gap\nvicinity at 2.1-2.4eV. The magnetic field and temperature dependence\ndemonstrates that the SHG arises from the bulk of the materials due to a novel\ntype of nonlinear optical susceptibility caused by the magnetic dipole\ncontribution combined with spontaneous or induced magnetization. This\nspin-induced susceptibility opens access to a wide class of centrosymmetric\nsystems by harmonics generation spectroscopy."
    },
    {
        "anchor": "Role of the defect-core in energetics of vacancies: Electronic structure calculations at macroscopic scales are employed to\ninvestigate the crucial role of a defect-core in the energetics of vacancies in\naluminum. We find that vacancy core-energy is significantly influenced by the\nstate of deformation at the vacancy-core, especially volumetric strains.\nInsights from the core electronic structure and computed displacement fields\nshow that this dependence on volumetric strains is closely related to the\nchanging nature of the core-structure under volumetric deformations. These\nresults are in sharp contrast to mechanics descriptions based on elastic\ninteractions that often consider defect core-energies as an inconsequential\nconstant. Calculations suggest that the variation in core-energies with\nchanging macroscopic deformations is quantitatively more significant than the\ncorresponding variation in relaxation energies associated with elastic fields.\nUpon studying the influence of various macroscopic deformations, which include\nvolumetric, uniaxial, biaxial and shear deformations, on the formation energies\nof vacancies, we show that volumetric deformations play a dominant role in\ngoverning the energetics of these defects. Further, by plotting formation\nenergies of vacancies and di-vacancies against the volumetric strain\ncorresponding to any macroscopic deformation, we find that all variations in\nthe formation energies collapse on to a universal curve. This suggests a\nuniversal role of volumetric strains in the energetics of vacancies.\nImplications of these results in the context of dynamic failure in metals due\nto spalling are analyzed.",
        "positive": "Low temperature magnetic and dielectric properties of LnBaCuFeO5 (Ln =\n  Nd, Eu, Gd, Ho and Yb): The layered perovskite compounds are interesting due to their intriguing\nphysical properties. In this article we report the structural, magnetic and\ndielectric properties of LnBaCuFeO5 (Ln=Nd, Eu, Gd, Ho and Yb). The structural\nparameters decrease from Nd to Yb due to the decrease in the ionic radii of the\nrare earth ions. An antiferromagnetic transition is observed for EuBaCuFeO5\nnear 120 K along with the glassy dynamics of the electric dipoles below 100 K.\nThe magnetic transition is absent in other compounds, which may be due to the\ndominance of the magnetic moment of the rare earth ions. The dielectric\nconstant does not show any anomaly, except in the case of HoBaCuFeO5 where it\nshows a weak frequency dependence around 54 K. These compounds show a\nsignificant enhancement of dielectric constant at high temperatures which have\nbeen attributed to Maxwell-Wagner effect. However, no significant\nmagneto-dielectric coupling has been observed in these layered perovskites."
    },
    {
        "anchor": "Hydration induced spin glass state in a frustrated Na-Mn-O triangular\n  lattice: Birnessite compounds are stable across a wide range of compositions that\nproduces a remarkable diversity in their physical, electrochemical and\nfunctional properties. These are hydrated analogues of the magnetically\nfrustrated, mixed-valent manganese oxide structures, with general formula,\nNaxMnO2. Here we demonstrate that the direct hydration of layered rock-salt\ntype a-NaMnO2, with the geometrically frustrated triangular lattice topology,\nyields the birnessite type oxide, Na0.36MnO2 0.2H2O, transforming its magnetic\nproperties. This compound has a much-expanded interlayer spacing compared to\nits parent a-NaMnO2 compound. We show that while the parent a-NaMnO2 possesses\na Neel temperature of 45 K as a result of broken symmetry in the Mn3+\nsub-lattice, the hydrated derivative undergoes collective spin-freezing at 29 K\nwithin the Mn3+/Mn4+ sub-lattice. Scaling-law analysis of the frequency\ndispersion of the AC susceptibility, as well as the temperature-dependent,\nlow-field DC magnetization confirm a cooperative spin-glass state of strongly\ninteracting spins. This is supported by complementary spectroscopic analysis\n(HAADF-STEM, EDS, EELS) as well as by a structural investigation\n(high-resolution TEM, X-ray and neutron powder diffraction) that yield insights\ninto the chemical and atomic structure modifications. We conclude that the\nspin-glass state in birnessite is driven by the spin-frustration imposed by the\nunderlying triangular lattice topology that is further enhanced by the in-plane\nbond-disorder generated by the mixed-valent character of manganese in the\nlayers.",
        "positive": "Ab initio study of the modification of elastic properties of alpha-iron\n  by hydrostatic strain and by hydrogen interstitials: The effect of hydrostatic strain and of interstitial hydrogen on the elastic\nproperties of $\\alpha$-iron is investigated using \\textit{ab initio}\ndensity-functional theory calculations. We find that the cubic elastic\nconstants and the polycrystalline elastic moduli to a good approximation\ndecrease linearly with increasing hydrogen concentration. This net strength\nreduction can be partitioned into a strengthening electronic effect which is\novercome by a softening volumetric effect. The calculated hydrogen-dependent\nelastic constants are used to determine the polycrystalline elastic moduli and\nanisotropic elastic shear moduli. For the key slip planes in $\\alpha$-iron,\n$[1\\bar{1}0]$ and $[11\\bar{2}]$, we find a shear modulus reduction of\napproximately 1.6% per at.% H."
    },
    {
        "anchor": "Persistence of structural distortion and bulk band Rashba splitting in\n  SnTe above its ferroelectric critical temperature: The ferroelectric semiconductor $\\alpha$-SnTe has been regarded as a\ntopological crystalline insulator and the dispersion of its surface states has\nbeen intensively measured with angle-resolved photoemission spectroscopy\n(ARPES) over the last decade. However, much less attention has been given to\nthe impact of the ferroelectric transition on its electronic structure, and in\nparticular on its bulk states. Here, we investigate the low-energy electronic\nstructure of $\\alpha$-SnTe with ARPES and follow the evolution of the\nbulk-state Rashba splitting as a function of temperature, across its\nferroelectric critical temperature of about $T_c\\sim 110$ K. Unexpectedly, we\nobserve a persistent band splitting up to room temperature, which is consistent\nwith an order-disorder contribution to the phase transition that requires the\npresence of fluctuating local dipoles above $T_c$. We conclude that no\ntopological surface state can occur at the (111) surface of SnTe, at odds with\nrecent literature.",
        "positive": "How the aggregation of oxygen vacancies in rutile based TiO$_{2-\u03b4}$\n  phases causes memristive behavior: The results of a comprehensive and systematic ab-initio based ground-state\nsearch for the structural arrangement of oxygen vacancies in rutile phase\nTiO$_2$ provide new insights into their memristive properties. We find that O\nvacancies tend to form planar arrangements which relax into structures\nexhibiting metallic behavior. These meta-stable arrangements are structurally\nakin to, yet distinguishable from the Magn\\'eli phase. They exhibit a more\npronounced metallic nature, but are energetically less favorable. Our results\nconfirm a clear structure-property relationship between segregated oxygen\nvacancy arrangement and metallic behavior in reduced oxides."
    },
    {
        "anchor": "Same and interconvertible high-pressure ice phases: Most experimentally known high-pressure ice phases have a body-centred cubic\n(bcc) oxygen lattice. Our atomistic simulations show that, amongst these bcc\nice phases, ices VII, VII' and X are the same thermodynamic phase under\ndifferent conditions, whereas superionic ice VII'' has a first-order phase\nboundary with ice VII'. Moreover, at about 300 GPa, ice X transforms into the\nPbcm phase with a sharp structural change but no apparent activation barrier,\nwhilst at higher pressures the barrier gradually increases. Our study thus\nclarifies the phase behaviour of the high-pressure insulating ices and reveals\npeculiar solid-solid transition mechanisms not known in other systems.",
        "positive": "Pure Spin Photocurrent in Non-centrosymmetric Crystals: Bulk Spin\n  Photovoltaic Effect: Spin current generators are critical components for spintronics-based\ninformation processing. In this work, we theoretically and computationally\ninvestigate the bulk spin photovoltaic (BSPV) effect for creating DC spin\ncurrent under light illumination. The only requirement for BPSV is inversion\nsymmetry breaking, thus it applies to a broad range of materials and can be\nreadily integrated with existing semiconductor technologies. The BSPV effect is\na cousin of the bulk photovoltaic (BPV) effect, whereby a DC charge current is\ngenerated under light. Thanks to the different selection rules on spin and\ncharge currents, a pure spin current can be realized if the system possesses\nmirror symmetry or inversion-mirror symmetry. The mechanism of BPSV and the\nrole of the electronic relaxation time $\\tau$ are also elucidated. We apply our\ntheory to several distinct material systems, including transition metal\ndichalcogenides, anti-ferromagnetic $\\rm MnBi_2Te_4$, and the surface of\ntopological crystalline insulator cubic $\\rm SnTe$."
    },
    {
        "anchor": "Apparent Differences between Single Layer Molybdenum Disulfide\n  Fabricated via Chemical Vapor Deposition and Exfoliation: Innovative applications based on two-dimensional solids require\ncost-effective fabrication processes resulting in large areas of high quality\nmaterials. Chemical vapour deposition is among the most promising methods to\nfulfill these requirements. However, for 2D materials prepared in this way it\nis generally assumed that they are of inferior quality in comparison to the\nexfoliated 2D materials commonly used in basic research. In this work we\nchallenge this assumption and aim to quantify the differences in quality for\nthe prototypical transition metal dichalcogenide MoS$_2$. To this end single\nlayers of MoS$_2$ prepared by different techniques (exfoliation, grown by\ndifferent chemical vapor deposition methods, transfer techniques, and as\nvertical heterostructure with graphene) are studied by Raman and\nphotoluminescence spectroscopy, complemented by atomic force microscopy. We\ndemonstrate that as-prepared MoS$_2$, directly grown on SiO$_2$, differs from\nexfoliated MoS$_2$ in terms of higher photoluminescence, lower electron\nconcentration, and increased strain. As soon as a water film is intercalated\n(e.g., by transfer) underneath the grown MoS$_2$, in particular the\n(opto-)electronic properties become practically identical to those of\nexfoliated MoS$_2$. A comparison of the two most common precursors shows that\nthe growth with MoO$_3$ causes greater strain and/or defect density deviations\nthan growth with ammonium heptamolybdate. As part of a heterostructure directly\ngrown MoS$_2$ interacts much stronger with the substrate, and in this case an\nintercalated water film does not lead to the complete decoupling, which is\ntypical for exfoliation or transfer. Our work shows that the supposedly poorer\nquality of grown 2D transition metal dichalcogenides is indeed a misconception.",
        "positive": "Vibrational properties of graphdiynes as 2D carbon materials beyond\n  graphene: Two-dimensional (2D) hybrid sp-sp2 carbon systems are an appealing subject\nfor science and technology. For these materials, topology and structure\nsignificantly affect electronic and vibrational properties. We investigate here\nby periodic density-functional theory (DFT) calculations we here investigate\nthe Raman and IR spectra of 2D carbon crystals belonging to the family of\ngraphdiynes (GDYs) and having different structures and topologies. By joining\nDFT calculations with symmetry analysis, we assign the IR and Raman modes in\nthe spectra of all the investigated systems. On this basis, we discuss how the\nmodulation of the Raman and IR active bands depends on the different\ninteractions between sp and sp2 domains. The symmetry-based classification\nallows identifying the marker bands sensitive to the different peculiar\ntopologies. These results show the effectiveness of vibrational spectroscopy\nfor the characterization of new nanostructures, deepening the knowledge of the\nsubtle interactions that take place in these 2D materials."
    },
    {
        "anchor": "Spark Plasma Sintering for high-speed diffusion welding of the ultrafine\n  grained near-a Ti-5Al-2V alloy with high strength and corrosion resistance\n  for nuclear engineering: The paper demonstrates the prospects of Spark Plasma Sintering (SPS) for the\nhigh-speed diffusion welding of the high-strength ultrafine-grained (UFG)\nnear-a Ti-5Al-2V alloy. The effect of increased diffusion welding intensity in\nthe UFG Ti alloys is discussed also. The welds of the UFG near-a-Ti-5Al-2V\nalloy obtained by SPS are featured by high density, strength, and corrosion\nresistance. The rate of weld sealing in the UFG alloys has been shown to depend\non the heating rate non-monotonously (with a pronounced maximum). At the stage\nof continuous heating and isothermic holding, the kinetics of the weld sealing\nwas found to be determined by the exponential creep rate, the intensity of\nwhich in the coarse-grained (CG) alloys is limited by the diffusion rate in the\ncrystal lattice whereas in the UFG alloys it is limited by the grain boundary\ndiffusion rate.",
        "positive": "Why the effective-mass approximation works so well for nano-structures: The reason why the effective-mass approximation, derived for wave packets\nconstructed from infinite-periodic-systems' wave functions, works so well with\nnanoscopic structures, has been an enigma and a challenge for theorists. To\nexplain and clarify this issue, we re-derive the effective-mass approximation\nin the framework of the theory of finite periodic systems, i.e., using energy\neigenvalues and fast-varying eigenfunctions, obtained with analytical methods\nwhere the finiteness of the number of primitive cells per layer, in the\ndirection of growth, is a prerequisite and an essential condition. This\nderivation justifies and explains why the effective-mass approximation works so\nwell for nano-structures. We show also with explicit optical-response\ncalculations that the rapidly varying eigenfunctions\n$\\Phi_{\\epsilon_0,\\eta_0}(z)$ of the one-band wave functions\n$\\Psi^{\\epsilon_0,\\eta_0}_{\\mu,\\nu}(z)= \\Psi^{\\epsilon_0}_{\\mu,\\nu}(z)\n\\Phi_{\\epsilon_0,\\eta_0}(z)$, can be safely dropped out for the calculation of\ninter-band transition matrix elements."
    },
    {
        "anchor": "Stabilization of AgI's polar surfaces by the aqueous environment, and\n  its implications for ice formation: Silver iodide is one of the most potent inorganic ice nucleating particles\nknown, a feature generally attributed to the excellent lattice match between\nits basal Ag-(0001) and I-(000-1) surfaces, and ice. This crystal termination,\nhowever, is a type-III polar surface, and its surface energy therefore diverges\nwith crystal size unless a polarity compensation mechanism prevails. In this\nsimulation study, we investigate to what extent the surrounding aqueous\nenvironment is able to provide such polarity compensation. On its own, we find\nthat pure water is unable to stabilize the AgI crystal in a physically\nreasonable manner, and that mobile charge carriers such as dissolved ions, are\nessential. In other words, proximate dissolved ions must be considered an\nintegral part of the heterogeneous ice formation mechanism. The simulations we\nperform utilize recent advances in simulation methodology in which appropriate\nelectric and electric displacement fields are imposed. A useful by-product of\nthis study is the direct comparison to the commonly used Yeh-Berkowitz method\nthat this enables. Here we find that naive application of the latter leads to\nphysically unreasonable results, and greatly influences the structure of water\nin the contact layer. We therefore expect these results to be of general\nimportance to those studying polar/charged surfaces in aqueous environments.",
        "positive": "Suppression of Magnetic Frustration by Doping in a nearest-neighbour\n  anti-ferromagnetic triangular lattice: Based on experimental observations in A{x}MO{2} (A = Na, Li; M = Co, Ni), a\nmodel for suppression of magnetic frustration by electron doping in a\nnearest-neighbour antiferromagnetic triangular lattice is presented. It is\nfound that frustration can be quantified, as determined by geometry and\nbond-counting, and its magnitude is a non-monotonic function of $x$. A\nmean-field calculation provides temperature-dependent magnetization,\nspin-entropy and heat capacity. Low-doping (x = 0.25, 0.33) results in a highly\nfrustrated regime. A{0.5}MO{2} has strongest order and no frustration, while\nhigh doping (x = 0.67, 0.75) leads to low frustration and higher spin-entropy.\nThe results agree with experiments including neutron scattering, spin\nentropy-driven thermoelectricity and ion ordering."
    },
    {
        "anchor": "Magnetization dynamics driven by angle-dependent spin-orbit spin\n  transfer torque: Spin-orbit spin transfer torque allows an efficient control of magnetization\nby an in-plane current. Recent experiments found that the spin-orbit torque has\nstrong dependence on the magnetization angle [Garello et al., Nature\nNanotechnol. 8, 587 (2013); Qiu et al., Sci. Rep. 4, 4491 (2014)]. We\ntheoretically investigate magnetization switching and domain wall motion in a\nperpendicularly magnetized layer, induced by angle-dependent spin-orbit torque.\nWe obtain analytic expressions of the switching current and domain wall\nvelocity, in agreement with numerical results. Based on the expressions, we\nfind that the spin-orbit torque increasing with the polar angle of\nmagnetization is beneficial for both switching and domain wall motion. Our\nresult will serve as a guideline to design and interpret switching and domain\nwall experiments based on spin-orbit torque.",
        "positive": "Exactly quantized dynamics of classical incommensurate sliders: We report peculiar velocity quantization phenomena in the classical motion of\nan idealized 1D solid lubricant, consisting of a harmonic chain interposed\nbetween two periodic sliders. The ratio v_cm/v_ext of the chain center-of-mass\nvelocity to the externally imposed relative velocity of the sliders stays\npinned to exact \"plateau\" values for wide ranges of parameters, such as sliders\ncorrugation amplitudes, external velocity, chain stiffness and dissipation, and\nis strictly determined by the commensurability ratios alone. The phenomenon is\nexplained by one slider rigidly dragging the kinks that the chain forms with\nthe other slider. Possible consequences of these results for some real systems\nare discussed."
    },
    {
        "anchor": "Crystalline C60 fulleride with metal inside: Endohedral metallofullerenes have been extensively studied, since the first\nexperimental observation of La@C60 in a laser-vaporized supersonic beam in\n1985. However, all of these studies have been carried out on metallofullerenes\nlarger than C60 such as (metal)@C82, and there are no reported purified\nC60-based metallofullerenes except for [Li@C60]+(SbCl6)- salt. Pure (metal)@C60\nhas not been obtained because of their extremely high chemical reactivity. We\nreport here the first isolation, structural determination and electromagnetic\nproperties of crystalline C60-based metallofullerenes, Gd@C60(CF3)5 and\nLa@C60(CF3)5. Synchrotron X-ray single-crystal diffraction reveals that La and\nGd atoms are indeed encapsulated in the Ih-C60 fullerene. The HOMO-LUMO gaps of\nGd@C60 and La@C60 are significantly widened by an order of magnitude with\naddition of CF3- groups. Magnetic measurements show the presense of a weak\nantiferromagnetic coupling in Gd@C60(CF3)3 crystals at low temperatures. Gd@C60\nand La@C60 might exhibit superconductivity as the electronic structures\nresemble those of superconducting alkali-doped C60 fullerides.",
        "positive": "Magnetotransport properties of iron microwires fabricated by focused\n  electron beam induced autocatalytic growth: We have prepared iron microwires in a combination of focused electron beam\ninduced deposition (FEBID) and autocatalytic growth from the iron\npentacarbonyl, Fe(CO)5, precursor gas under UHV conditions. The electrical\ntransport properties of the microwires were investigated and it was found that\nthe temperature dependence of the longitudinal resistivity (rhoxx) shows a\ntypical metallic behaviour with a room temperature value of about 88\nmicro{\\Omega} cm. In order to investigate the magnetotransport properties we\nhave measured the isothermal Hall-resistivities in the range between 4.2 K and\n260 K. From these measurements positive values for the ordinary and the\nanomalous Hall coefficients were derived. The relation between anomalous Hall\nresistivity (rhoAN) and longitudinal resistivity is quadratic, rhoAN rho^2 xx,\nrevealing an intrinsic origin of the anomalous Hall effect. Finally, at low\ntemperature in the transversal geometry a negative magnetoresistance of about\n0.2 % was measured."
    },
    {
        "anchor": "Competing magnetic interactions in spin-1/2 square lattice: hidden order\n  in Sr$_2$VO$_4$: With decreasing temperature Sr$_2$VO$_4$ undergoes two structural phase\ntransitions, tetragonal-to-orthorhombic-to-tetragonal, without long-range\nmagnetic order. Recent experiments suggest, that only at very low temperature\nSr$_{2}$VO$_{4}$ might enter some, yet unknown, phase with long-range magnetic\norder, but without orthorhombic distortion. By combining relativistic density\nfunctional theory with an extended spin-1/2 compass-Heisenberg model we find an\nantiferromagnetic single-stripe ground state with highly competing exchange\ninteractions, involving a non negligible inter-layer coupling, which places the\nsystem at the crossover between between the XY and Heisenberg picture. Most\nstrikingly, we find a strong two-site \"spin-compass\" exchange anisotropy which\nis relieved by the orthorhombic distortion induced by the spin stripe order.\nBased on these results we discuss the origin of the hidden order phase and the\npossible formation of a spin-liquid at low temperatures.",
        "positive": "Multi-excitonic complexes in single InGaN quantum dots: Cathodoluminescence spectra employing a shadow mask technique of InGaN layers\ngrown by metal organic chemical vapor deposition on Si(111) substrates are\nreported. Sharp lines originating from InGaN quantum dots are observed.\nTemperature dependent measurements reveal thermally induced carrier\nredistribution between the quantum dots. Spectral diffusion is observed and was\nused as a tool to correlate up to three lines that originate from the same\nquantum dot. Variation of excitation density leads to identification of exciton\nand biexciton. Binding and anti-binding complexes are discovered."
    },
    {
        "anchor": "Dynamic control of the optical emission from GaN/InGaN nanowire quantum\n  dots by surface acoustic waves: The optical emission of InGaN quantum dots embedded in GaN nanowires is\ndynamically controlled by a surface acoustic wave (SAW). The emission energy of\nboth the exciton and biexciton lines is modulated over a 1.5 meV range at ~330\nMHz. A small but systematic difference in the exciton and biexciton spectral\nmodulation reveals a linear change of the biexciton binding energy with the SAW\namplitude. The present results are relevant for the dynamic control of\nindividual single photon emitters based on nitride semiconductors.",
        "positive": "Nature of the Structural Symmetries Associated with Hybrid Improper\n  Ferroelectricity in Ca3X2O7: In hybrid improper ferroelectric systems, polarization arises from the onset\nof successive nonpolar lattice modes. In this work, measurements and modeling\nwere performed to determine the spatial symmetries of the phases involved in\nthe transitions to these modes. Structural and optical measurements reveal that\nthe tilt and rotation distortions of the MnO6 or TiO6 polyhedra relative to the\nhigh symmetry phases driving ferroelectricity in the hybrid improper Ca3X2O7\nsystem (X=Mn and Ti) condense at different temperatures. The tilt angle\nvanishes abruptly at T$_T$ ~ 400 K for Ca3Mn2O7 (and continuously for X=Ti) and\nthe rotation mode amplitude is suppressed at much higher temperatures T$_R$\n~1060 K. Moreover, Raman measurements in Ca3Mn2O7 under isotropic pressure\nreveal that the polyhedral tilts can be suppressed by very low pressures\n(between 1.4 and2.3 GPa) indicating their softness. These results indicate that\nthe Ca3Mn2O7 system provides a new platform for strain engineering of\nferroelectric properties in film based systems with substrate induced strain."
    },
    {
        "anchor": "On the generalized method of cells and the prediction of effective\n  elastic properties of polymer bonded explosives: The prediction of the effective elastic properties of polymer bonded\nexplosives using direct numerical simulations is computationally expensive\nbecause of the high volume fraction of particles in these particulate\ncomposites ($\\sim$0.90) and the strong modulus contrast between the particles\nand the binder ($\\sim$20,000). The generalized method of cells (GMC) is an\nalternative to direct numerical simulations for the determination of effective\nelastic properties of composites. GMC has been shown to be more computationally\nefficient than finite element analysis based approaches for a range of\ncomposites. In this investigation, the applicability of GMC to the\ndetermination of effective elastic properties of polymer bonded explosives is\nexplored. GMC is shown to generate excellent estimates of effective moduli for\ncomposites containing square arrays of disks at volume fractions less than 0.60\nand a modulus contrast of approximately 100.",
        "positive": "Dynamic fracture of a bicontinuously nanostructured copolymer: A\n  deep-learning analysis of big-data-generating experiment: Here, we report measurements of detailed dynamic cohesive properties (DCPs)\nbeyond the dynamic fracture toughness of a bicontinuously nanostructured\ncopolymer, polyurea, under an extremely loading rate, from deep-learning\nanalyses of a dynamic big-data-generating experiment. We first describe a new\nDynamic Line-Image Shearing Interferometer (DL-ISI), which uses a streak camera\nto record optical fringes of displacement-gradient vs time profile along a line\non sample's rear surface. This system enables us to detect crack initiation and\ngrowth processes in plate-impact experiments. Then, we present a convolutional\nneural network (CNN) based deep-learning framework, trained by extensive\nfinite-element simulations, that inversely determines the accurate DCPs from\nthe DL-ISI fringe images. For the measurements, plate-impact experiments were\nperformed on a set of samples with a mid-plane crack. A Conditional Generative\nAdversarial Networks (cGAN) was employed first to reconstruct missing DL-ISI\nfringes with recorded partial DL-ISI fringes. Then, the CNN and a correlation\nmethod were applied to the fully reconstructed fringes to get the dynamic\nfracture toughness, 12.1kJ/m^2, cohesive strength, 302 MPa, and maximum\ncohesive separation, 80.5 um, within 0.4%, 2.7%, and 2.2% differences,\nrespectively. For the first time, the DCPs of polyurea have been successfully\nobtained by the DL-ISI with the pre-trained CNN and correlation analyses of\ncGAN-reconstructed data sets. The dynamic cohesive strength is found to be\nnearly three times higher than the dynamic-failure-initiation strength. The\nhigh dynamic fracture toughness is found to stem from both high dynamic\ncohesive strength and high ductility of the dynamic cohesive separation."
    },
    {
        "anchor": "Off-center impurities in alkali halides: reorientation, electric\n  polarization and binding to F center. V. Temperature-dependent electrostatic\n  polarizabilities: We derive and discuss expressions for the temperature-dependent electrostatic\npolarizabilities of off-center ions holding good under various experimental\nconditions. At low temperatures and electric-field strengths, all of them\nreasonably reduce to values characteristic of phonon-coupled two-level systems.\nProspects for further studies of the dispersive coupling are also considered.",
        "positive": "In-situ liquid SAXS studies on the early stage of calcium carbonate\n  formation: Calcium carbonate is a model system to investigate the mechanism of solid\nformation by precipitation from solutions, and it is often considered in the\ndebated classical and non-classical nucleation mechanism. Despite the great\nscientific relevance of calcium carbonate in different areas of science, little\nis known about the early stage of its formation. We, therefore, designed\ncontactless devices capable to provide informative investigations on the early\nstages of the precipitation pathway of calcium carbonate in supersaturated\nsolutions using classical scattering methods such as Wide-Angle X-ray\nScattering (WAXS) and Small-Angle X-ray Scattering (SAXS) techniques. In\nparticular, SAXS was exploited for investigating the size of entities formed\nfrom supersaturated solutions before the critical conditions for amorphous\ncalcium carbonate (ACC) nucleation are attained. The saturation level was\ncontrolled by mixing four diluted solutions (i.e., NaOH, CaCl2, NaHCO3, H2O) at\nconstant T and pH. The scattering data were collected on a liquid jet generated\nabout 75 sec after the mixing point. The data were modeled using parametric\nstatistical models providing insight about the size distribution of denser\nmatter in the liquid jet. Theoretical implications on the early stage of solid\nformation pathway are inferred."
    },
    {
        "anchor": "Substantial optical dielectric enhancement by volume compression in\n  LiAsSe$_2$: Based on first-principles calculations, we predict a substantial increase in\nthe optical dielectric function of LiAsSe$_2$ under pressure. We find that the\noptical dielectric constant is enhanced threefold under volume compression.\nThis enhancement is mainly due to the dimerization strength reduction of the\none-dimensional (1D) As--Se chains in LiAsSe$_2$, which significantly alters\nthe wavefunction phase mismatch between two neighboring chains and changes the\ntransition intensity. By developing a tight-binding model of the interacting 1D\nchains, the essential features of the low-energy electronic structure of\nLiAsSe$_2$ are captured. Our findings are important for understanding the\nfundamental physics of LiAsSe$_2$ and provide a feasible way to enhance the\nmaterial optical response that can be applied to light harvesting for energy\napplications.",
        "positive": "A simple denoising approach to exploit multi-fidelity data for machine\n  learning materials properties: Machine-learning models have recently encountered enormous success for\npredicting the properties of materials. These are often trained based on data\nthat present various levels of accuracy, with typically much less high- than\nlow-fidelity data. In order to extract as much information as possible from all\navailable data, we here introduce an approach which aims to improve the quality\nof the data through denoising. We investigate the possibilities that it offers\nin the case of the prediction of the band gap relying on both limited\nexperimental data and density-functional theory relying different\nexchange-correlation functionals (with an increasing amount of data as the\naccuracy of the functional decreases). We explore different ways to combine the\ndata into training sequences and analyze the effect of the chosen denoiser.\nFinally, we analyze the effect of applying the denoising procedure several\ntimes until convergence. Our approach provides an improvement over existing\nmethods to exploit multi-fidelity data."
    },
    {
        "anchor": "Electrostatic doping of graphene through ultrathin hexagonal boron\n  nitride films: When combined with graphene, hexagonal boron nitride (h-BN) is an ideal\nsubstrate and gate dielectric with which to build metalh-BN|graphene\nfield-effect devices. We use first-principles density functional theory (DFT)\ncalculations for Cu|h-BN|graphene stacks to study how the graphene doping\ndepends on the thickness of the h-BN layer and on a potential difference\napplied between Cu and graphene. We develop an analytical model that describes\nthe doping very well, allowing us to identify the key parameters that govern\nthe device behaviour. A predicted intrinsic doping of graphene is particularly\nprominent for ultrathin h-BN layers and should be observable in experiment. It\nis dominated by novel interface terms that we evaluate from DFT calculations\nfor the individual materials and for interfaces between h-BN and Cu or\ngraphene.",
        "positive": "Ultralow friction of ink-jet printed graphene flakes: We report the frictional response of few-layer graphene (FLG) flakes obtained\nby liquid phase exfoliation (LPE) of pristine graphite. To this end, we inkjet\nprint FLG on bare and hexamethyldisilazane-terminated SiO2 substrates,\nproducing micrometric patterns with nanoscopic roughness that are investigated\nby atomic force microscopy. Normal force spectroscopy and atomically resolved\nmorphologies indicate reduced surface contamination by solvents after a vacuum\nannealing procedure. Notably, the printed FLG flakes show ultralow friction\ncomparable with micromechanically exfoliated graphene flakes. Lubricity is\nretained on flakes with lateral size of a few tens of nanometres, and with\nthickness as small as ~ 2 nm, confirming the high crystalline quality and low\ndefects density in the FLG basal plane. Surface exposed step edges exhibit the\nhighest friction values, representing preferential sites for originating\nsecondary dissipative processes related to edge straining, wear or lateral\ndisplacement of the flakes. Our work demonstrates that LPE enables fundamental\nstudies on graphene friction to the single-flake level. The capability to\ndeliver ultralow-friction-graphene over technologically relevant substrates,\nusing a scalable production route and a high-throughput, large-area printing\ntechnique, may also open up new opportunities in the lubrication of micro- and\nnano-electromechanical systems."
    },
    {
        "anchor": "Ion beam sputtering of silicon: Energy distributions of sputtered and\n  scattered ions: The properties of sputtered and scattered ions are studied for ion beam\nsputtering of Si by bombardment with noble gas ions. The energy distributions\nin dependence on ion beam parameters (ion energy: 0.5 - 1 keV; ion species: Ne,\nAr, Xe) and geometrical parameters (ion incidence angle, polar emission angle,\nscattering angle) are measured by means of energy-selective mass spectrometry.\nThe presence of anisotropic effects due to direct sputtering and scattering is\ndiscussed and correlated with process parameters. The experimental results are\ncompared to calculations based on a simple elastic binary collision model and\nto simulations using the Monte-Carlo code SDTrimSP. The influence of the\ncontribution of implanted primary ions on energy distributions of sputtered and\nscattered particles is studied in simulations. It is found that a 10\\%\nvariation of the target composition leads to detectable but small differences\nin the energy distributions of scattered ions. Comparison with previously\nreported data for other ion/target configurations confirms the presence of\nsimilar trends and anisotropic effects: the number of high-energy sputtered\nions increases with increasing energy of incident ions and decreasing\nscattering angle. The effect of the ion/target mass ratio is additionally\ninvestigated. Small differences are observed with the change of the primary ion\nspecies: the closer the mass ratio to unity, the higher the average energy of\nsputtered ions. The presence of peaks, assigned to different mechanisms of\ndirect scattering, strongly depends on the ion/target mass ratio.",
        "positive": "Evolution of phase morphology in dispersed clay systems under the\n  microwave irradiation: The results of a study of the effect of microvolume emission (power 700 W,\nfrequency 2.45 GHz) on the structural changes in natural clay particles are\npresented. The influence of the irradiation time (10 and 20 minutes) and the\nenvironment in the microwave chamber (atmospheric air and air saturated with\nwater vapor) on the structural changes occurring in the particles was traced.\nDuring the first 10 minutes, capillary water is completely removed and\nagglomeration is carried out by attaching single dispersed particles (diffusion\nlimited aggregation model). At the second stage (10-20 minutes), already formed\nagglomerates (cluster-cluster aggregation model) are growing. A complex of\nindependent optical-physical methods was used to analyze weak structural\nchanges. It includes X-ray phase analysis, colorimetry and wavelet analysis.\nThis approach has made it possible to increase the information content and\nreliability of measurements, quantitatively characterize the structural\nresponses in disperse clay systems. In the air, the removal of capillary water\nis accompanied by agglomerations of particles and polymorphic transformations\nof oxides: montmorillonite is completely decomposed, amorphous phases\ncrystallize. The composition of the environment in the microwave chamber\naffects the type of phase transformations in iron compounds: iron-alumina is\nformed in air, magnetite appear in the water vapor medium. The studies carried\nout using the developed set of experimental methods indicate the possibility of\nregulating the processes of structure formation in disperse clay systems by\noptimizing the regimes of exposure to microwave radiation."
    },
    {
        "anchor": "3D Coupled Thermo-Mechanical Phase-Field Modeling of Shape Memory Alloy\n  Dynamics via Isogeometric Analysis: The paper focuses on numerical simulation of the phase-field (PF) equations\nfor modeling martensitic transformations in shape memory alloys (SMAs), their\ncomplex microstructures and thermo-mechanical behavior. The PF model is based\non the Landau-Ginzburg potential for the 3D cubic-to-tetragonal phase\ntransformations in SMAs. The treatment of domain walls as diffuse interfaces,\nleads to a fourth-order differential equation in a strain-based order parameter\nPF model. The fourth-order equations introduce a number of unexplored numerical\nchallenges because traditional numerical schemes have been primarily applied to\nsecond-order problems. We propose isogeometric analysis (IGA) as a numerical\nformulation for a straightforward solution to the fourth-order differential PF\nequations using continuously differentiable non-uniform rational B-splines\n(NURBS). We present microstructure evolution in different geometries of SMA\nnanostructures under temperature-induced phase transformations to illustrate\nthe geometrical flexibility, accuracy and robustness of our approach. The\nsimulations successfully capture the dynamic thermo-mechanical behavior of SMAs\nobserved experimentally.",
        "positive": "Conduction eigenchannels of atomic-sized contacts: Ab initio KKR Green's\n  function formalism: We develop a formalism for the evaluation of conduction eigenchannels of\natomic-sized contacts from first-principles. The multiple scattering\nKorringa-Kohn-Rostoker (KKR) Green's function method is combined with the Kubo\nlinear response theory. Solutions of the eigenvalue problem for the\ntransmission matrix are proven to be identical to eigenchannels introduced by\nLandauer and B{\\\"u}ttiker. Applications of the method are presented by studying\nballistic electron transport through Cu, Pd, Ni and Co single-atom contacts. We\nshow in detail how the eigenchannels are classified in terms of irreducible\nrepresentations of the symmetry group of the system as well as by orbital\ncontributions when the channels wave functions are projected on the contact\natom."
    },
    {
        "anchor": "Effect of heavy ion irradiation on microstructure and electron density\n  distribution of zirconium alloy characterised by X-ray diffraction technique: Different techniques of the X-ray Diffraction Line Profile Analysis (XRDLPA)\nhave been used to assess the microstructure of the irradiated\nZr-1.0%Nb-1.0%Sn-0.1%Fe alloy. The domain size, microstrain, density of\ndislocation and the stacking fault probabilities of the irradiated alloy have\nbeen estimated as a function of dose by the Williamson-Hall Technique, Modified\nRietveld Analysis and the Double Voigt Method. A clear signature in the\nincrease in the density of dislocation with the dose of irradiated was\nrevealed. The analysis also estimated the average density of dislocation in the\nmajor slip planes after irradiation. For the first time, we have established\nthe changes in the electron density distribution due to irradiation by X-ray\ndiffraction technique. We could estimate the average displacement of the atoms\nand the lattice strain caused due to irradiation from the changes in the\nelectron density distribution as observed in the contour plots.",
        "positive": "Intrinsic effects of substitution and intercalation on thermal transport\n  in two-dimensional TiS$_2$ single crystals: The promising thermoelectric material TiS$_2$ can be easily chemically doped\nand intercalated. We present here studies of single crystals that are\nintercalated with excess Ti or Co, or substituted with Ta. We demonstrate the\nintrinsic impact of these dopants on the thermal transport in the absence of\ngrain boundary scattering. We show that Ta doping has the greatest impact on\nthe thermal scattering rate per ion added, leading to a five-fold reduction in\nthe lattice thermal conductivity as compared to stoichiometric single crystals."
    },
    {
        "anchor": "The role of Coulomb and exchange interaction on the\n  Dzyaloshinskii-Moriya interaction(DMI) in BiFeO3: Ab initio calculations show that the Dzyaloshinskii-Moriya\ninteraction(DMI)and net magnetization per unit cell in BiFeO3 are reduced when\nU is increasing from 0 to 2.9 eV, and independent of $J$. Interestingly, the\nDMI is even destroyed as $U$ exceeds a critical value of 2.9 eV. We propose a\nsimple model to explain this phenomenon and present the nature of the rotation\nof the magnetization corresponding to altered antiferrodistortive distortions\nunder DMI in BiFeO3.",
        "positive": "Waviness affects friction and abrasive wear: To prolong lifetime and reduce energy consumption, a thorough understanding\nof abrasive wear is essential. The potentially crucial influence of surface\ntopography intricacies on tribological behavior have been obscured, since\nroughness and waviness are often considered simple scalar quantities. Here, the\ncomplete waviness profile of the sliding track was used to shed light on the\ninfluence of surface topography on abrasive wear. Bearing steel pins and disks\nwere tribologically tested with Al2O3-based slurries as interfacial medium. It\nwas found that even small surface deviations (albeit minimized and controlled\nfor) can significantly increase the friction coefficient - up to 91 %. Not only\nare frictional fluctuations strongly correlated with the disks' initial\nwaviness profile, these small fluctuations correlate with unevenly-distributed\nhigh wear."
    },
    {
        "anchor": "Platelet-zone in an age-hardening Mg-Zn-Gd alloy: The structure of a unique platelet zone with a three close-packed layer\nthickness, which occurred in a Mg-1at.%Zn-2at.%Gd alloy annealed at low\ntemperatures (<~500K), has been determined based on scanning transmission\nelectron microscopy and first principles calculations.",
        "positive": "Indexing Fe-phases in/on GaN using x-ray powder diffraction: This document reports the x-ray powder diffraction main reflections\n(intensity threshold >= 100) for possible Fe-related phases forming during the\nmetal-organic vapor phase epitaxy (MOVPE) growth of Fe in NH_3/H_2 mixture on\nwurtzite-GaN/sapphire. The 2\\theta values are given for Cu K\\alpha_1 radiation\n(1.5406 \\AA) in the range 25-100 deg (ordered by increasing 2\\theta). The\nGaN(000l) and Al_2O_3(000l) are also reported for reference."
    },
    {
        "anchor": "Molecular static simulation of edge dislocation core in bcc iron: We simulate the dislocation core structure in bcc iron using the modified\nMolecular Static method. A feature of this method is the application of an\niterative procedure in which the atomic structure in the vicinity of the defect\nand the constants that determine the displacements of atoms immersed in the\nelastic continuum are calculated in a self-consistent manner. Following the\nmentioned approach, we develop a model for calculating the atomic structure of\nedge dislocations, taking into account the anisotropy of the elastic medium\nsurrounding the main calculation cell. Anisotropy is taken into account by\nintroducing an explicit angular dependence for the parameters of the elastic\nfield created by the dislocation: magnitude of Burgers vector and Poisson's\nratio. Simulation is carried out for a split dislocation with Burgers vector\nalong [100]. The convergence of the iterative algorithm is shown and the\ninfluence of the computational cell size on the results is considered.\nCalculated results are: atomic structure of dislocation in bcc iron, angular\ndependence of the parameters describing the elastic dislocation field at large\ndistances from the dislocation line, and the strain tensor components in the\nentire simulation area.",
        "positive": "Scaling for the Coalescence of Microfractures before Breakdown: We study the behavior of fracture in disordered systems close to the\nbreakdown point. We simulate numerically both scalar (resistor network) and\nvectorial (spring network) models with threshold disorder, driven at constant\ncurrent and stress rate respectively. We analyze the scaling of the\nsusceptibility and the cluster size close to the breakdown. We observe\navalanche behavior and clustering of the cracks. We find that the scaling\nexponents are consistent with those found close to a mean-field spinodal and\npresent analogies between the coalescence of microfractures and the coalescence\nof droplets in a metastable magnetic system. Finally, we discuss different\nexperimental conditions and some possible theoretical interpretations of the\nresults."
    },
    {
        "anchor": "Ferri-chiral compounds with potentially switchable Dresselhaus spin\n  split-ting: Spin splitting of energy bands can be induced by relativistic spin-orbit\ninteractions in materials without inversion symmetry. Whereas polar space group\nsymmetries permit Rashba (R-1) spin splitting with helical spin textures in\nmomentum space, which could be reversed upon switching a ferroelectric\npolarization via applied electric fields, the ordinary Dresselhaus effect\n(D-1A) is ac-tive only in materials exhibiting nonpolar noncentrosymmetric\ncrystal classes with atoms occupy-ing exclusively non-polar lattice sites.\nConsequently, the spin-momentum locking induced by D-1A is not electric\nfield-switchable. An alternative type of Dresselhaus symmetry, referred to as\nD-1B, exhibits crystal class constraints similar to D-1A (all dipoles add up to\nzero), but unlike D-1A, at least one polar site is occupied. We find that this\nbehavior exists in a class of ferri-chiral crys-tals, which in principle could\nbe reversed upon a change in chirality. Focusing on alkali metal chalcogenides,\nwe identify NaCu5S3 in the nonentiamorphic ferri-chiral structure, which\nexhibits CuS3 chiral units differing in the magnitude of their Cu\ndisplacements. We then synthesize NaCu5S3 (space group P6322) and confirm its\nferri-chiral structure with power x-ray diffraction. Our electronic structure\ncalculations demonstrate it exhibits D-1B spin splitting as well as a\nferri-chiral phase transition, revealing spin splitting interdependent on\nchirality. Our electronic struc-ture calculations show that a few percent\nbiaxial tensile strain can reduce (or nearly quench) the switching barrier\nseparating the monodomain ferri-chiral P6322 states. We discuss what type of\nexternal stimuli might switch the chirality so as to reverse the (non-helical)\nDresselhaus D-1B spin texture, offering an alternative to the traditional\nreversal of the (helical) Rashba spin texture.",
        "positive": "Orbital hybridization induced band offset phenomena in NixCd1-xO thin\n  films: We present the cationic impurity assisted band offset phenomena in NixCd1-xO\n(x= 0, 0.02, 0.05, 0.1, 0.2, 0.4, 0.8, 1) thin films and further discussed in\nthe light of orbital hybridization modification. Compositional and structural\nstudies revealed that cationic substitution of Cd2+ by Ni2+ ions leads to a\nmonotonic shift in (220) diffraction peak, indicating the suppression of\nlattice distortion while evolution of local strain with increasing Ni\nconcentration mainly associated to the mismatch in electro-negativity of Cd2+\nand Ni2+ ion. In fact, Fermi level pinning towards conduction band minima takes\nplace with increasing Ni concentration at the cost of electronically\ncompensated oxygen vacancies, resulting modification in the distribution of\ncarrier concentration which eventually affects the band edge effective mass of\nconduction band electrons and further endorses band gap renormalization.\nBesides that, the appearance of longitudinal optical (LO) mode at 477 cm-1 as\nmanifested by Raman spectroscopy also indicate the active involvement of\nelectron-phonon scattering whereas modification in local coordination\nenvironment particularly anti-crossing interaction in conjunction with presence\nof satellite features and shake-up states with Ni doping is confirmed by X-ray\nabsorption near-edge and X-ray photoelectron spectroscopy studies. These\nresults manifest the gradual reduction of orbital hybridization with Ni\nincorporation, leading to decrement in the band edge effective mass of\nelectron. Finally, molecular dynamics simulation reflects 13% reduction in\nlattice parameter for NiO thin film as compared to undoped one while projected\ndensity of states calculation further supports the experimental observation of\nreduced orbital hybridization with increasing Ni concentration."
    },
    {
        "anchor": "Neutron scattering from local magnetoelectric multipoles: a combined\n  theoretical, computational, and experimental perspective: We address magnetic neutron scattering in the presence of local\nnon-centrosymmetric asymmetries of the magnetization density. Such\ninversion-symmetry breaking, combined with the absence of time-reversal\nsymmetry, can be described in terms of magnetoelectric multipoles which form\nthe second term after the magnetic dipole in the multipole expansion of the\nmagnetization density. We provide a pedagogical review of the theoretical\nformalism of magnetic neutron diffraction in terms of the multipole expansion\nof the scattering cross-section. In particular, we show how to compute the\ncontribution of magnetoelectric multipoles to the scattering amplitude starting\nfrom ab initio calculations. We also provide general guidelines on how to\nexperimentally detect long-ranged order of magnetoelectric multipoles using\neither unpolarized or polarized neutron scattering. As a case study, we search\nfor the presence of magnetoelectric multipoles in CuO by comparing theoretical\nfirst-principle predictions with experimental spherical neutron polarimetry\nmeasurements.",
        "positive": "A new comparison between solid-state thermionics and thermoelectrics: It is shown that equations for electrical current in solid-state thermionic\nand thermoelectric devices converge for devices with a width equal to the mean\nfree path of electrons, yielding a common expression for intensive electronic\nefficiency in the two types of devices. This result is used to demonstrate that\nthe materials parameters for thermionic and thermoelectric devices are equal,\nrather than differing by a multiplicative factor as previously thought."
    },
    {
        "anchor": "Valley polarization assisted spin polarization in two dimensions: Valleytronics is rapidly emerging as an exciting area of basic and applied\nresearch. In two dimensional systems, valley polarisation can dramatically\nmodify physical properties through electron-electron interactions as\ndemonstrated by such phenomena as the fractional quantum Hall effect and the\nmetal-insulator transition. Here, we address the electrons' spin alignment in a\nmagnetic field in silicon-on-insulator quantum wells under valley polarisation.\nIn stark contrast to expectations from a non-interacting model, we show\nexperimentally that less magnetic field can be required to fully spin polarise\na valley-polarised system than a valley-degenerate one. Furthermore, we show\nthat these observations are quantitatively described by parameter free ab\ninitio quantum Monte Carlo simulations. We interpret the results as a\nmanifestation of the greater stability of the spin and valley degenerate system\nagainst ferromagnetic instability and Wigner crystalisation which in turn\nsuggests the existence of a new strongly correlated electron liquid at low\nelectron densities.",
        "positive": "Crystalline Ni nanoparticles as the origin of ferromagnetism in Ni\n  implanted ZnO crystals: We report the structural and magnetic properties of ZnO single crystals\nimplanted at 623 K with up to 10 at. % of Ni. As revealed by X-ray diffraction,\ncrystalline fcc-Ni nanoparticles were formed inside ZnO. The magnetic behavior\n(magnetization with field reversal and with different temperature protocol) of\nall samples is well explained by a magnetic Ni-nanoparticle system. Although\nthe formation of Ni:ZnO based diluted magnetic semiconductor cannot be ruled\nout, the major contribution to the magnetic properties stems from crystalline\nnanoparticles synthesized under these implantation conditions."
    },
    {
        "anchor": "Design and performance of an ultrahigh vacuum spectroscopic-imaging\n  scanning tunneling microscope with a hybrid vibration isolation system: A spectroscopic imaging-scanning tunneling microscope (SI-STM) allows the\natomic scale visualization of surface electronic and magnetic structure of\nnovel quantum materials with high energy resolution. To achieve the optimal\nperformance, low vibration facility is required. Here, we describe the design\nand the performance of an ultrahigh vacuum STM system supported by a hybrid\nvibration isolation system that consists of a pneumatic passive and a\npiezoelectric active vibration isolation stages. The STM system is equipped\nwith a 1K pot cryogenic insert and a 9 Tesla superconducting magnet, capable of\ncontinuous SI-STM measurements for 7 days. A field ion microscopy system is\ninstalled for in situ STM tip treatment. We present the detailed vibrational\nnoise analysis of the hybrid vibration isolation system and demonstrate the\nperformance of our STM system by taking high resolution spectroscopic maps and\ntopographic images on several quantum materials. Our results establish a new\nstrategy to achieve an effective vibration isolation system for high-resolution\nSTM and other scanning probe microscopy to investigate the nanoscale quantum\nphenomena.",
        "positive": "Hybrid carbon nanostructure as a nano computing memory device: This paper has been withdrawn by the author due to a the manuscript error."
    },
    {
        "anchor": "Decoupling the effects of composition and strain on the vibrational\n  modes of GeSn: We report on the behavior of Ge-Ge, Ge-Sn, Sn-Sn like and disorder-activated\nvibrational modes in GeSn semiconductors investigated using Raman scattering\nspectroscopy. By using an excitation wavelength close to E1 gap, all modes are\nclearly resolved and their evolution as a function of strain and Sn content is\nestablished. In order to decouple the individual contribution of content and\nstrain, the analysis was conducted on series of pseudomorphic and relaxed\nepitaxial layers with a Sn content in the 5-17at.% range. All vibrational modes\nwere found to display the same qualitative behavior as a function of content\nand strain, viz. a linear downshift as the Sn content increases or the\ncompressive strain relaxes. Simultaneously, Ge-Sn and Ge-Ge peaks broaden, and\nthe latter becomes increasingly asymmetric. This asymmetry, coupled with the\npeak position, is exploited in an empirical method to accurately quantify the\nSn composition and lattice strain from Raman spectra.",
        "positive": "Magnetic phase diagram of rare-earth orthorhombic perovskite oxides: Spin reorientation and magnetisation reversal are two important features of\nthe rare-earth orthorhombic provskites ($RM$O$_{3}$'s) that have attracted a\nlot of attention, though their exact microscopic origin has eluded researchers.\nHere, using density functional theory and classical atomistic spin dynamics we\nbuild a general Heisenberg magnetic model that allows to explore the whole\nphase diagram of the chromite and ferrite compounds and to scrutinize the\nmicroscopic mechanism responsible for spin reorientations and magnetisation\nreversals. We show that the occurrence of a magnetization reversal transition\ndepends on the relative strength and sign of two interactions between\nrare-earth and transition-metal atoms: superexchange and Dzyaloshinsky-Moriya.\nWe also conclude that the presence of a smooth spin reorientation transition\nbetween the so-called $\\Gamma_4$ and the $\\Gamma_2$ phases through a coexisting\nregion, and the temperature range in which it occurs, depends on subtle balance\nof metal--metal (superexchange and Dzyaloshinsky-Moriya) and metal--rare-earth\n(Dzyaloshinsky-Moriya) couplings. In particular, we show that the intermediate\ncoexistence region occurs because the spin sublattices rotate at different\nrates."
    },
    {
        "anchor": "Designing Disordered Hyperuniform Two-Phase Materials with Novel\n  Physical Properties: Heterogeneous materials consisting of different phases are ideally suited to\nachieve a broad spectrum of desirable bulk physical properties by combining the\nbest features of the constituents through the strategic spatial arrangement of\nthe different phases. Disordered hyperuniform heterogeneous materials are new,\nexotic amorphous matter that behave like crystals in the manner in which they\nsuppress volume-fraction fluctuations at large length scales, and yet are\nisotropic with no Bragg peaks. In this paper, we formulate for the first time a\nFourier-space numerical construction procedure to design at will a wide class\nof disordered hyperuniform two-phase materials with prescribed spectral\ndensities, which enables one to tune the degree and length scales at which this\nsuppression occurs. We demonstrate that the anomalous suppression of\nvolume-fraction fluctuations in such two-phase materials endow them with novel\nand often optimal transport and electromagnetic properties. Specifically, we\nconstruct a family of phase-inversion-symmetric materials with variable\ntopological connectedness properties that remarkably achieves a well-known\nexplicit formula for the effective electrical (thermal) conductivity. Moreover,\nwe design disordered stealthy hyperuniform dispersion that possesses nearly\noptimal effective conductivity while being statistically isotropic.\nInterestingly, all of our designed materials are transparent to electromagnetic\nradiation for certain wavelengths, which is a common attribute of all\nhyperuniform materials. Our constructed materials can be readily realized by 3D\nprinting and lithographic technologies. We expect that our designs will be\npotentially useful for energy-saving materials, batteries and aerospace\napplications.",
        "positive": "First principles calculations of Structure and electrostatic properties\n  of non ligated CdSe nanoclusters: Structural and charge relaxation of nanoclusters of CdSe of diameter 1-2 nm\nare studied with first principle calculations. The relaxations cause\nsignificant distortions of smaller systems of ~ 1 nm in diameter and have very\nminimal effect on the larger systems of ~ 2 nm in diameter. The Cd atoms are\npulled in while the Se atoms are pulled out, which results in the flattening of\nCd-terminated surface and retention of a zig-zag surface for Se-terminated\nsurface. The surfaces terminated with both Cd and Se result in significant\ngeometrical distortion resulting in charge concentrations at the distorted\nsites. The associated dipole and quadrupole moments are a function of the\ndistortion or unequal distribution of Cd and Se. The HOMO and HOMO-1 orbitals\nare located on or near the distortions. Based on the tetrahedral coordination\nand robustness of the core structure to surface relaxation, the approx. 2 nm\ndiameter NC is the best candidate for building macroscopic structures from NCs."
    },
    {
        "anchor": "Density functional study of alkali metal atoms and monolayers on\n  graphite (0001): Alkali metal atoms (Li, Na, K, Rb, Cs), dimers and (2$\\times$2) monolayers on\na graphite (0001) surface have been studied using density functional theory,\npseudopotentials, and a periodic substrate. The adatoms bind at the hollow site\n(graphite hexagon), with Li lying closest to (1.84 \\AA) and Cs farthest (3.75\n{\\AA}) from the surface. The adsorption energies range between $0.55-1.21$ eV,\nand the energy ordering of the alkali adatoms is Li$>$Cs$\\ge$Rb$\\ge$K$>$Na. The\nsmall diffusion barriers (0.02-0.21 eV for the C-C bridge) decrease as the atom\nsize increases, indicating a flat potential energy surface. The formation\n(cohesion) energies of (2$\\times$2) monolayers range between 0.55-0.81 eV,\nwhere K has the largest value, and increased coverage weakens the\nadsorbate-substrate interaction (decoupling) while a two-dimensional metallic\nfilm is formed. Analysis of the charge density redistribution upon adsorption\nshows that the alkali metal adatoms donate a charge of $0.4-0.5 e$ to graphite,\nand the corresponding values for (2$\\times$2) monolayers are $\\sim 0.1 e$ per\natom. The transferred charge resides mostly in the $\\pi$-bands (atomic\n$p_z$-orbitals) of the outermost graphene layer.",
        "positive": "Bimolecular theory of non-radiative recombination in semiconductors with\n  disorder: The original Shockley-Read-Hall recombination statistics is extended to\ninclude recombination of localized excitations. The recombination is treated as\na bimolecular process rather than a monomolecular recombination of excitons.\nThe emphasis is placed on an interplay between two distinct channels of\nradiative recombination (shallow localized states vs extended states) mediated\nby trapping of photogenerated charge carriers by non-radiative centers. Results\nof a numerical solution for a given set of parameters are complemented by an\napproximate analytical expression for the thermal quenching of the\nphotoluminescence intensity in non-degenerate semiconductors derived in the\nlimit of low pump intensities. The merit of a popular double-exponential\nempirical function for fitting the thermal quenching of the photoluminescence\nintensity is critically examined."
    },
    {
        "anchor": "The role of native defects in the transport of charge and mass and the\n  decomposition of Li$_{4}$BN$_{3}$H$_{10}$: Li$_{4}$BN$_{3}$H$_{10}$ is of great interest for hydrogen storage and for\nlithium-ion battery solid electrolytes because of its high hydrogen content and\nhigh lithium-ion conductivity, respectively. The practical hydrogen storage\napplication of this complex hydride is, however, limited due to irreversibility\nand cogeneration of ammonia (NH$_{3}$) during the decomposition. We report a\nfirst-principles density-functional theory study of native point defects and\ndefect complexes in Li$_{4}$BN$_{3}$H$_{10}$, and propose an atomistic\nmechanism for the material's decomposition that involves mass transport\nmediated by native defects. In light of this specific mechanism, we argue that\nthe release of NH$_{3}$ is associated with the formation and migration of\nnegatively charged hydrogen vacancies inside the material, and it can be\nmanipulated by the incorporation of suitable electrically active impurities. We\nalso find that Li$_{4}$BN$_{3}$H$_{10}$ is prone to Frenkel disorder on the Li\nsublattice; lithium vacancies and interstitials are highly mobile and play an\nimportant role in mass transport and ionic conduction.",
        "positive": "Magnetostriction of AlFe2B2 in High Magnetic Fields: Using the experimental capability of the novel X-ray diffraction instrument\navailable at the 25 Tesla Florida Split Coil Magnet at the NHMFL, Tallahassee\nwe present an extensive investigation on the magnetostriction of\npolycrystalline AlFe2B2. The magnetostriction was measured near the\nferromagnetic transition temperature (Curie temperature TC = 280 K, determined\nvia DC magnetization measurements), namely, at 250, 290, and 300 K. AlFe2B2\nexhibits an anisotropic change in lattice parameters as a function of magnetic\nfield near the Curie temperature, and a monotonic variation as a function of\napplied field has been observed, i.e., the c-axis increases significantly while\nthe a- and b-axes decrease with the increasing field in the vicinity of TC,\nirrespective of the measurement temperature. The volume magnetostriction\ndecreases with decreasing temperature and changes its sign across TC. Density\nfunctional theory calculations for the non-polarized and spin-polarized\n(ferromagnetic) models confirm that the observed changes in lattice parameters\ndue to spin polarization are consistent with the experiment. The relationships\nfor magnetostriction are estimated based on a simplified Landau model that\nagrees well with the experimental results."
    },
    {
        "anchor": "Lattice dynamics and negative thermal expansion in the framework\n  compound ZnNi(CN)$_4$ with two-dimensional and three-dimensional local\n  environments: ZnNi(CN)$_4$ is a 3D framework material consisting of two interpenetrating\nPtS-type networks in which tetrahedral [ZnN$_4$] units are linked by\nsquare-planar [NiC$_4$] units. Both the parent compounds, cubic Zn(CN)$_2$ and\nlayered Ni(CN)$_2$, are known to exhibit 3D and 2D negative thermal expansion\n(NTE), respectively. Temperature-dependent inelastic neutron scattering\nmeasurements were performed on a powdered sample of ZnNi(CN)$_4$ to probe\nphonon dynamics. The measurements were underpinned by ab initio lattice\ndynamical calculations. Good agreement was found between the measured and\ncalculated generalized phonon density-of-states, validating our theoretical\nmodel and indicating that it is a good representation of the dynamics of the\nstructural units. The calculated linear thermal expansion coefficients are\n$\\alpha_a$=-21.2 $\\times$ 10$^{-6}$ K$^{-1}$ and\n$\\alpha_c$=+14.6$\\times$10$^{-6}$K$^{-1}$, leading to an overall volume\nexpansion coefficient $\\alpha_V$ of -26.95$\\times$10$^{-6}$K$^{-1}$, pointing\ntowards pronounced NTE behavior. Analysis of the derived mode-Gr\\\"uneisen\nparameters shows that optic modes around 12 and 40 meV make a significant\ncontribution to NTE. These modes involve localized rotational motions of the\n[NiC$_4$] and/or [ZnN$_4$] rigid units, echoing what has previously been\nobserved in Zn(CN)$_2$ and Ni(CN)$_2$. However, in ZnNi(CN)$_4$, modes below 10\nmeV have the most negative Gr\\\"uneisen parameters. Analysis of their\neigenvectors reveals that a large transverse motion of the Ni atom in the\ndirection perpendicular to its square-planar environment induces a distortion\nof the units. This mode is a consequence of the Ni atom being constrained only\nin 2D within a 3D framework. Hence, although rigid-unit modes account for some\nof the NTE-driving phonons, the added d-o-f compared with Zn(CN)$_2$ results in\nmodes with twisting motions, capable of inducing greater NTE.",
        "positive": "Evidence of surface transport and weak anti-localization in single\n  crystal of Bi2Te2Se topological insulator: Topological insulators are known to their metallic surface states, a result\nof strong-spin-orbital coupling, that show unique surface transport phenomenon.\nBut these surface transports are buried in presence of metallic bulk\nconduction. We synthesized very high quality Bi$_2$Te$_2$Se single crystals by\nmodified Bridgman method, that possess high bulk resistivity of\n$>$20~$\\Omega$cm below 20~K, whereas the bulk is mostly inactive and surface\ntransport dominates. Temperature dependence resistivity follows the activation\nlaw like a gap semiconductor in temperature range 20-300~K. We designed a\nspecial measurement geometry, which aims to extract the surface transport from\nthe bulk. This special geometry is applied to measure the resistance and found\nthat Bi$_2$Te$_2$Se single crystal exhibits a cross over from bulk to surface\nconduction at 20~K. Simultaneously, the material also shows strong evidence of\nweak anti-localization in magneto-transport due to the protection against\nscattering by conducting surface states. This novel simple geometry is an easy\nroute to find the evidence of surface transport in topological insulators,\nwhich are the promising materials for future spintronic applications."
    },
    {
        "anchor": "Confinement effect on solar thermal heating process of TiN solutions: We propose a theoretical approach to describe quantitatively the heating\nprocess in aqueous solutions of dispersed TiN nanoparticles under solar\nillumination. The temperature gradients of solution with different\nconcentrations of TiN nanoparticles are calculated when confinement effects of\nthe container on the solar absorption are taken into account. We find that the\naverage penetration of solar radiation into the solution is significantly\nreduced with increasing the nanoparticle concentration. At high concentrations,\nour numerical results show that photons are localized near the surface of the\nsolution. Moreover, the heat energy balance equation at the vapor-liquid\ninterface is used to describe the solar steam generation. The theoretical time\ndependence of temperature rise and vaporization weight losses is consistent\nwith experiments. Our calculations give strong evidence that the substantially\nlocalized heating near the vapor-liquid interface is the main reason for the\nmore efficient steam generation process by floating plasmonic membranes when\ncompared to randomly dispersed nanoparticles. The validated theoretical model\nsuggests that our approach can be applied towards new predictions and other\nexperimental data descriptions.",
        "positive": "Exchange bias associated with phase separation in the Nd2/3Ca1/3MnO3\n  manganite: The exchange bias (EB) phenomenon has been found in Nd2/3Ca1/3MnO3\nperovskite. The phenomenon manifests itself as a negative horizontal shift of\nmagnetization hysteresis loops. The EB phenomenon is evident of an interface\nexchange coupling between coexisting antiferromagnetic (AFM) and ferromagnetic\n(FM) phases and confirms the phase separated state of the compound at low\ntemperatures. The EB effect is found to be strongly dependent on the cooling\nmagnetic field and the temperature, which is associated with the evolution of\nspontaneous AFM - FM phase separated state of the compound. Analysis of\nmagnetic hysteresis loops has shown that ferromagnetic moment $M_{FM}$\noriginating from the FM clusters saturates in a relatively low magnetic field\nabout H ~ 0.4T. The obtained saturation value $M_{FM}$(1T) ~ 0.45$\\mu_{B}$ is\nin a good agreement with our previous neutron diffraction data."
    },
    {
        "anchor": "Predicting Phonon-Induced Spin Decoherence from First Principles:\n  Colossal Spin Renormalization in Condensed Matter: Developing a microscopic understanding of spin decoherence is essential to\nadvancing quantum technologies. Electron spin decoherence due to atomic\nvibrations (phonons) plays a special role as it sets an intrinsic limit to the\nperformance of spin-based quantum devices. Two main sources of phonon-induced\nspin decoherence - the Elliott-Yafet (EY) and Dyakonov-Perel (DP) mechanisms -\nhave distinct physical origins and theoretical treatments. Here we show\ncalculations that unify their modeling and enable accurate predictions of spin\nrelaxation and precession in semiconductors. We compute the phonon-dressed\nvertex of the spin-spin correlation function, with a treatment analogous to the\ncalculation of the anomalous electron magnetic moment in QED. We find that the\nvertex correction provides a giant renormalization of the electron spin\ndynamics in solids, greater by many orders of magnitude than the corresponding\ncorrection in vacuum. Our work demonstrates a general approach for quantitative\nanalysis of spin decoherence in materials, advancing the quest for spin-based\nquantum technologies.",
        "positive": "Analytical determination of the reach-through breakdown voltage of\n  bipolar transistors, asymmetric thyristors and Punch Through-IGBTs: In this work, an analytical formula that gives the reach-through breakdown\nvoltage of bipolar transistors, asymmetric thyristors, Punch Through-IGBTs and\nother devices with similar structure is deduced for the first time."
    },
    {
        "anchor": "Epitaxial growth of graphene-like silicon nano-ribbons: Graphene, a flat monolayer of carbon atoms tightly packed into a\ntwo-dimensional honeycomb lattice (a one atom thick graphite sheet), is\npresently the hottest material in nanoscience and nanotechnology. Its\nchallenging hypothetical reflection in the silicon world is coined silicene;\nHere, we have demonstrated that the silicon nano-wires self-aligned in a\nmassively parallel array recently observed by STM on Ag(110), are true silicene\nnano-ribbons. Our calculations using density functional theory clearly show\nthat Si atoms tends to form hexagons on top the silver substrate in a\nhoneycomb, graphene-like arrangement.",
        "positive": "Transmission Electron Microscopy Studies on RF Sputtered Copper Ferrite\n  Thin Films: Copper ferrite thin films were rf sputtered at a power of 50W. The as\ndeposited films were annealed in air at 800{\\deg}C and slow cooled. The\ntransmission electron microscope (TEM) studies were carried out on as deposited\nas well as on slow cooled film. Significantly larger defect concentration,\nincluding stacking faults, was observed in 50W as deposited films than the\nfilms deposited at a higher rf power of 200W. The film annealed at 800{\\deg}C\nand then slow cooled showed an unusual grain growth upto 180nm for a film\nthickness of ~240nm. These grains showed Kikuchi pattern."
    },
    {
        "anchor": "Prediction of weak topological insulators in layered semiconductors: We report the discovery of weak topological insulators by ab initio\ncalculations in a honeycomb lattice. We propose a structure with an odd number\nof layers in the primitive unit-cell as a prerequisite for forming weak\ntopological insulators. Here, the single-layered KHgSb is the most suitable\ncandidate for its large bulk energy gap of 0.24 eV. Its side surface hosts\nmetallic surface states, forming two anisotropic Dirac cones. Though the\nstacking of even-layered structures leads to trivial insulators, the structures\ncan host a quantum spin Hall layer with a large bulk gap, if an additional\nsingle layer exists as a stacking fault in the crystal. The reported honeycomb\ncompounds can serve as prototypes to aid in the finding of new weak topological\ninsulators in layered small-gap semiconductors.",
        "positive": "Destruction of graphene by metal adatoms: The formation energies for mono- and bivacancies in graphene in the presence\nof adatoms of various metals and small metallic clusters have been calculated.\nIt is shown that transition metal impurities, such as iron, nickel and,\nespecially, cobalt reduce dramatically the vacancy formation energies whereas\ngold impurities have almost no effect on characteristics of the vacancies. This\nresults highlight that special measures are required in order to protect\ngraphene from damage by transition metal leads."
    },
    {
        "anchor": "Interband spin-orbit coupling between anti-parallel spin states in Pb\n  quantum well states: Using spin and angle-resolved photoemission spectroscopy we investigate a\nmomentum region in Pb quantum well states on Si(111) where hybridization\nbetween Rashba-split bands alters the band structure significantly. Starting\nfrom the Rashba regime where the dispersion of the quasi-free two-dimensional\nelectron gas is well described by two spin-polarized parabolas, we find a\nbreakdown of the Rashba behavior which manifests itself (i) in a spin splitting\nthat is no longer proportional to the in-plane momentum and (ii) in a reversal\nof the sign of the momentum splitting. Our experimental findings are well\nexplained by including interband spin-orbit coupling that mixes Rashba-split\nstates with anti-parallel rather than parallel spins. Similar results for\nPb/Cu(111) reveal that the proposed hybridization scenario is independent on\nthe supporting substrate.",
        "positive": "Ultrafast pseudomagnetic fields from electron-nuclear quantum geometry: Recent experiments demonstrate precise control over coherently excited phonon\nmodes using high-intensity terahertz lasers, opening new pathways towards\ndynamical, ultrafast design of magnetism in functional materials. In this work,\nwe put forward a coupling mechanism based on electron-nuclear quantum geometry.\nThis effect is rooted in the phase accumulation of the electronic wavefunction\nunder a circular evolution of nuclear coordinates. An excitation pulse then\ninduces a transient level splitting between electronic orbitals that carry\nangular momentum. When converted to effective magnetic fields, values on the\norder of tens of Teslas are easily reached."
    },
    {
        "anchor": "Inducing Quantum Phase Transitions in Non-Topological Insulators Via\n  Atomic Control of Sub-Structural Elements: Topological insulators (TIs) are an important family of quantum materials\nthat exhibit a Dirac point (DP) in the surface band structure but have a finite\nband gap in bulk. A large degree of spin-orbit interaction and low bandgap is a\nprerequisite for stabilizing DPs on selective atomically flat cleavage planes.\nTuning of the DP in these materials has been suggested via modifications to the\natomic structure of the entire system. Using the example of As$_2$Te$_3$ and\nZnTe$_5$, which are not TIs, we show that a quantum phase transition can be\ninduced in atomically flat and stepped surfaces, for As$_2$Te$_3$ and ZrTe$_5$,\nrespectively. This is achieved by establishing a framework for controlling\nelectronic properties that is focused on local perturbations at key locations\nthat we call sub-structural elements (SSEs). We exemplify this framework\nthrough a novel method of isovalent sublayer anion doping and biaxial strain.",
        "positive": "Microwave assisted resonant domain wall nucleation in permalloy\n  nanowires: We have designed a system to study microwave assisted domain wall nucleation\nin permalloy nanowires. We find a substantial decrease in the nucleation field\nwhen microwave fields are applied, in comparison to pulse fields. A clear\nresonance peak is observed in the frequency dependence of the nucleation field,\nwhich coincides with the uniform mode ferromagnetic resonance frequency. Owing\nto the well-defined nucleation process, the switching field distribution is\nsmall in contrast to previous reports. Our results show that localized\nmicrowave field provides an efficient tool for injecting domain walls into\nmagnetic nanowires."
    },
    {
        "anchor": "Restoring the density-gradient expansion for exchange in solids and\n  surfaces: Successful modern generalized gradient approximations (GGA's) are biased\ntoward atomic energies. Restoration of the first-principles gradient expansion\nfor exchange over a wide range of density gradients eliminates this bias. We\nintroduce PBEsol, a revised Perdew-Burke-Ernzerhof GGA that improves\nequilibrium properties of densely-packed solids and their surfaces.",
        "positive": "AFLOW-CCE for the thermodynamics of ionic materials: Accurate thermodynamic stability predictions enable data-driven computational\nmaterials design. Standard density functional theory (DFT) approximations have\nlimited accuracy with average errors of a few hundred meV/atom for ionic\nmaterials such as oxides and nitrides. Thus, insightful correction schemes as\ngiven by the coordination corrected enthalpies (CCE) method, based on an\nintuitive parameterization of DFT errors with respect to coordination numbers\nand cation oxidation states present a simple, yet accurate solution to enable\nmaterials stability assessments. Here, we illustrate the computational\ncapabilities of our AFLOW-CCE software by utilizing our previous results for\noxides and introducing new results for nitrides. The implementation reduces the\ndeviations between theory and experiment to the order of the room temperature\nthermal energy scale, i.e. ~25 meV/atom. The automated corrections for both\nmaterials classes are freely available within the AFLOW ecosystem via the\nAFLOW-CCE module, requiring only structural inputs."
    },
    {
        "anchor": "Momentum dependence of the excitons in pentacene: We have carried out electron energy-loss investigations of the lowest singlet\nexcitons in pentacene at 20 K. Our studies allow to determine the full exciton\nband structure in the a*,b* reciprocal lattice plane. The lowest singlet\nexciton can move coherently within this plane, and the resulting exciton\ndispersion is highly anisotropic. The analysis of the energetically following\n(satellite) features indicates a strong admixture of charge transfer\nexcitations to the exciton wave function.",
        "positive": "A streamlined approach to mapping the magnetic induction of skyrmionic\n  materials: Recently, Lorentz transmission electron microscopy (LTEM) has helped\nresearchers advance the emerging field of magnetic skyrmions. These magnetic\nquasi-particles, composed of topologically non-trivial magnetization textures,\nhave a large potential for application as information carriers in low-power\nmemory and logic devices. LTEM is one of a very few techniques for direct real\nspace imaging of magnetic features at the nanoscale. For Fresnel-contrast LTEM,\nthe transport of intensity equation (TIE) is the tool of choice for\nquantitative reconstruction of the local magnetic induction through the sample\nthickness. Typically this analysis requires collection of at least three\nimages.Here we show that for uniform thin magnetic films which includes many\nskyrmionic samples, the magnetic induction can be quantitatively determined\nfrom a single defocused image using a simplified TIE approach."
    },
    {
        "anchor": "Polar domains in lead titanate films under tensile strain: Thin films of PbTiO3, a classical ferroelectric, have been grown under\ntensile strain on single-crystal substrates of DyScO3. The films, of only 5nm\nthickness, grow fully coherent with the substrate and show no crystallographic\ntwin domains, as evidenced by synchrotron x-ray diffraction. A mapping of the\nreciprocal space reveals intensity modulations (satellites) due to\nregularly-spaced polar domains in which the polarization appears rotated away\nfrom the substrate normal, characterizing a low symmetry phase not observed in\nthe bulk material. This could have important practical implications since these\nphases are known to be responsible for ultrahigh piezoelectric responses in\ncomplex systems.",
        "positive": "Adiabatic Joule Heating of Copper from 4 K to the Melting Temperature: Considering a copper wire heated by Joule effect and the variation of its\nresistivity and specific heat with temperature, we established numerical and\nanalytical solutions (between 293 and 1356 K for the latter) for the evolution\nof its temperature over time. The Temperature vs. Time evolution follows a\nLambertian function. The calculations are based on the assumption of adiabatic\nheating and uniform current distribution within the wire. We demonstrate that\nat very low temperature the heating rate is strongly dependent on copper\npurity."
    },
    {
        "anchor": "Equation of state, phonons, and lattice stability of ultra-fast warm\n  dense matter: Using the two-temperature model for ultrafast matter (UFM), we compare the\nequation of state, pair-distribution functions $g(r)$, and phonons using the\nneutral pseudoatom (NPA) model with results from density-functional theory\n(DFT) codes and molecular-dynamics (MD) simulations for Al, Li and Na. The NPA\napproach uses state-dependent first-principles pseudopotentials from an\n`all-electron' DFT calculation with finite-$T$ XCF. It provides pair\npotentials, structure factors, the\n  `bound' and `free' states, as well as a mean ionization $\\bar{Z}$\nunambiguously. These are not easily accessible {\\it via} DFT+MD calculations\nwhich become prohibitive for $T/T_F$ exceeding $\\sim 0.6$, where $T_F$ is the\nFermi temperature. Hence, both DFT+MD and NPA methods can be compared up to\n$\\sim 8$ eV, while higher $T$ can be addressed ${\\it via}$ the NPA. The\nhigh-$T_e$ phonon calculations raise the question of UFM lattice stability and\nsurface ablation in thin UFM samples. The ablation forces in a UFM slab are\nused to define an \"ablation time\" competing with phonon formation times in thin\nUFM samples. Excellent agreement for all properties is found between NPA and\nstandard DFT codes, even for Li where a strongly non-local pseudopotential is\nused in DFT codes. The need to use pseudopotentials appropriate to the\nionization state $\\bar{Z}$ is emphasized. The effect of finite-$T$\nexchange-correlation functional is illustrated via its effect on the pressure\nand the electron-density distribution at a nucleus.",
        "positive": "Polytypes of long-period stacking structures synchronized with chemical\n  order in a dilute Mg-Zn-Y alloy: A series of structural polytypes formed in an Mg-1at.%Zn-2at.%Y alloy has\nbeen identified, which are reasonably viewed as long-period stacking\nderivatives of the hcp Mg structure with alternate AB stacking of the\nclose-packed atomic layers. Atomic-resolution Z-contrast imaging clearly\nrevealed that the structures are long-period chemical-ordered as well as\nstacking-ordered; unique chemical order along the stacking direction occurs as\nbeing synchronized with a local faulted stacking of AB'C'A, where B' and C'\nlayers are commonly enriched by Zn/Y atoms."
    },
    {
        "anchor": "The role of single oxygen or metal induced defect and correlated\n  multiple defects in the formation of conducting filaments: We study the dependence of the formation energies of oxygen and metal induced\ndefects in Ta2O5, TaO2, TaO, TiO2 and Ti4O7 on the chemical potential of\nelectron and atomic constitutes. In the study of single defect, metal induced\ndefects are found to be preferable to oxygen induced defects. This is against\nthe experimental fact of the dominant role of oxygen induced defects in the RS\nprocess. A simple multiple defects picture without correlated atomic\nrearrangement does not cure this problem. The problem is resolved under the\ncorrelated multiple defect picture where the multiple defects result in\ncorrelated atomic rearrangement and the final products show certain atomic\nordering.",
        "positive": "Trajectory dependence of electronic energy-loss straggling at keV ion\n  energies: We have measured the electronic energy-loss straggling of protons, helium,\nboron and silicon ions in silicon using a transmission time-of-flight approach.\nIons with velocities between 0.25 and 1.6 times the Bohr velocity were\ntransmitted through single-crystalline Si(100) nanomembranes in either\nchannelling or random geometry to study the impact parameter dependence of\nenergy-loss straggling. Nuclear and path length contributions to the straggling\nwere determined with the help of Monte Carlo simulations. Our results exhibit\nan increase in straggling with increasing ion velocity for channelled\ntrajectories for all projectiles as well as for protons and helium in random\ngeometry. In contrast for heavier ions, electronic straggling at low velocities\ndoes not decrease further but plateaus and even seems to increase again. We\ncompare our experimental results with transport cross section calculations. The\nsatisfying agreement for helium shows that electronic stopping for light ions\nis dominated by electron-hole pair excitations, and that the previously\nobserved trajectory dependence can indeed be attributed to a higher mean charge\nstate for random trajectories. No agreement is found for boron and silicon\nindicating the breakdown of models based solely on electron-hole pair\nexcitations, and that local electron-promotion and charge-exchange events\nsignificantly contribute to energy loss at low velocities."
    },
    {
        "anchor": "Shear-Transformation-Zone Theory of Linear Glassy Dynamics: We present a linearized shear-transformation-zone (STZ) theory of glassy\ndynamics in which the internal STZ transition rates are characterized by a\nbroad distribution of activation barriers. For slowly aging or fully aged\nsystems, the main features of the barrier-height distribution are determined by\nthe effective temperature and other near-equilibrium properties of the\nconfigurational degrees of freedom. Our theory accounts for the wide range of\nrelaxation rates observed in both structural glasses and soft glassy materials\nsuch as colloidal suspensions. We find that the frequency dependent loss\nmodulus is not just a superposition of Maxwell modes. Rather, it exhibits an\n$\\alpha$ peak that rises near the viscous relaxation rate and, for nearly\njammed, glassy systems, extends to much higher frequencies in accord with\nexperimental observations. We also use this theory to compute strain recovery\nfollowing a period of large, persistent deformation and then abrupt unloading.\nWe find that strain recovery is determined in part by the initial\nbarrier-height distribution, but that true structural aging also occurs during\nthis process and determines the system's response to subsequent perturbations.\nIn particular, we find by comparison with experimental data that the initial\ndeformation produces a highly disordered state with a large population of low\nactivation barriers, and that this state relaxes quickly toward one in which\nthe distribution is dominated by the high barriers predicted by the\nnear-equilibrium analysis. The nonequilibrium dynamics of the barrier-height\ndistribution is the most important of the issues raised and left unresolved in\nthis paper.",
        "positive": "Well-defined Cu$_2$O photocatalysts for solar fuels and chemicals: The shape-controlled synthesis of cuprous oxide (Cu$_2$O) photocatalysts with\nboth low or high index crystal planes has received increasing attention due to\ntheir unique facet-dependent properties. Since they are cheap and earth\nabundant, these well-defined Cu$_2$O nanostructures are extensively used for\ndifferent photocatalytic reactions, also because of their strong visible light\nabsorption capability. However, further development will be still needed to\nenhance the efficiency and photostability of Cu$_2$O, which still limits its\nindustrial application. We start this review by summarizing the synthetic\nadvancement in the facet engineering of Cu$_2$O and other associated hybrid\nCu$_2$O-based heterostructures with a special emphasis put on their growth\nmechanism. We then discuss different facet-dependent properties, which are\nrelevant to photocatalysis. In the subsequent section, we present a critical\ndiscussion on the photocatalytic performance of faceted Cu$_2$O nanostructures\nduring organic synthesis, hydrogen production, and carbon dioxide\nphotoreduction. The relation between photocatalytic efficiency and product\nselectivity with exposed crystal facets or with different composition of hybrid\nnanostructures is also discussed. Finally, important strategies are proposed to\novercome the photostability issue, while outlining the course of future\ndevelopment to further boost the technological readiness of well-defined\nCu$_2$O-based photocatalysts."
    },
    {
        "anchor": "Domain wall pinning and hard magnetic phase in Co-doped bulk single\n  crystalline Fe3GeTe2: We report the effects of cobalt doping on the magnetic properties of\ntwo-dimensional van der Waals ferromagnet Fe3GeTe2. Single crystals of\n(Fe{1-x}Cox)3GeTe2 with x=0-0.78 were successfully synthesized and\ncharacterized with x-ray diffraction, energy dispersive x-ray spectroscopy and\nmagnetization measurements. Both the Curie-Weiss temperature and ferromagnetic\n(FM) ordered moment of Fe3GeTe2 are gradually suppressed upon Co doping. A kink\nin zero-field-cooling low field M(T) curve which is previously explained as an\nantiferromagnetic transition is observed for samples with x=0-0.58. Our\ndetailed magnetization measurements and theoretical calculations strongly\nsuggest that this kink is originated from the pinning of magnetic domain walls.\nThe domain pinning effects are suddenly enhanced when the doping concentration\nof cobalt is around 50%, both the coercive field Hc and the magnetic remanence\nto saturated magnetization ratio MR/MS are largely improved and a hard magnetic\nphase emerges in bulk single crystal samples. The strong doping dependent\nmagnetic properties suggest more spintronic applications of Fe3GeTe2.",
        "positive": "Higher-order Quantum Spin Hall Effect of Light: Band topology and related spin (or pseudo-spin) physics of photons provide us\nwith a new dimension for manipulating light, which is potentially useful for\ninformation communication and data storage. Especially, the quantum spin Hall\neffect of light, where electromagnetic waves propagate along surfaces of\nsamples with strong spin-momentum locking, paves the way for achieving\ntopologically protected photonic spin transport. Recently, the conventional\nbulk-edge correspondence of the band topology has been extended to higher-order\ncases that enables the explorations of topological states with codimensions\nlarger than 1 such as hinge and corner states. Here, for the first time, we\ndemonstrate a higherorder quantum spin Hall effect of light by utilizing an\nall-dielectric C6v-symmetric photonic crystal. We observe corner states with\nopposite pseudospin polarizations at different corners owing to nontrivial\nhigher-order topology and finite spin-spin coupling. By applying the\nspin-polarized excitation sources, we can selectively excite the corner states\nat different spatial positions through spin-momentum-locked decaying edge\nstates, resembling the quantum spin Hall effect in a higher-order manner. Our\nwork which breaks the barriers between the spin photonics and higher-order\ntopology opens the frontiers for studying lower-dimensional spinful classical\nsurface waves and supports explorations in robust communications."
    },
    {
        "anchor": "Polaronic nature of a muonium-related paramagnetic center in SrTiO$_3$: The hyperfine features and thermal stability of a muonium (Mu)-related\nparamagnetic center were investigated in the SrTiO$_3$ perovskite titanate via\nmuon spin rotation spectroscopy. The hyperfine coupling tensor of the\nparamagnetic center was found to have prominent dipolar characteristics,\nindicating that the electron spin density is dominantly distributed on a Ti\nsite to form a small polaron near an ionized Mu$^+$ donor. Based on a\nhydrogen-Mu analogy, interstitial hydrogen is also expected to form such a\npolaronic center in the dilute doping limit. The small activation energy of\n30(3) meV found for the thermal dissociation of the Mu$^+$-polaron complex\nsuggests that the strain energy required to distort the lattice is comparable\nto the electronic energy gained by localizing the electron.",
        "positive": "Measurement of swelling-induced residual stress in ion implanted SiC,\n  and its effect on micromechanical properties: Ion implantation is widely used as a surrogate for neutron irradiation in the\ninvestigation of radiation damage on the properties of materials. Due to the\nsmall depth of damage, micromechanical methods must be used to extract material\nproperties. In this work, nanoindentation has been applied to ion irradiated\nsilicon carbide to extract radiation-induced hardening. Residual stress is\nevaluated using HR-EBSD, AFM swelling measurements, and a novel microcantilever\nrelaxation technique coupled with finite element modelling. Large compressive\nresidual stresses of several GPa are found in the irradiated material, which\ncontribute to the significant hardening observed in nanoindentation\nmeasurements. The origin of these residual stresses and the associated\nhardening is the unirradiated substrate which constrains radiation swelling.\nComparisons with other materials susceptible to irradiation swelling show that\nthis effect should not be neglected in studying the effects of ion irradiation\ndamage on mechanical properties. This constraint may also be influencing\nfundamental radiation defects. This has significant implications for the\nsuitability of ion implantation as a surrogate for neutron irradiations. These\nresults demonstrate the significance of swelling-induced residual stresses in\nnuclear reactor components, and the impact on structural integrity of reactor\ncomponents."
    },
    {
        "anchor": "Relativistic quasiparticle self-consistent electronic structure of\n  hybrid halide perovskite photovoltaic absorbers: Solar cells based on a light absorbing layer of the organometal halide\nperovskite CH$_3$NH$_3$PbI$_3$ have recently reached 15% conversion efficiency,\nthough how these materials work remains largely unknown. We analyse the\nelectronic structure and optical properties within the quasiparticle\nself-consistent GW approximation. While this compound bears some similarity to\nconventional sp semiconductors, it also displays unique features. Quasiparticle\nself-consistency is essential for an accurate description of the band\nstructure: bandgaps are much larger than what is predicted by the local density\napproximation (LDA) or GW based on the LDA. Valence band dispersions are\nmodified in a very unusual manner. In addition, spin orbit coupling strongly\nmodifies the band structure and gives rise to unconventional dispersion\nrelations and a Dresselhaus splitting at the band edges. The average hole mass\nis small, which accounts for the long diffusion lengths recently observed. The\nsurface ionisation potential (workfunction) is calculated to be 5.7 eV with\nrespect to the vacuum level, explaining efficient carrier transfer to TiO$_2$\nand Au electrical contacts.",
        "positive": "New ground states of fluorinated and oxidized phosphorene: structural\n  and electronic properties: We systematically explore chemical functionalization of monolayer black\nphosphorene via chemisorption of oxygen and fluorine atoms. Using the cluster\nexpansion technique, with vary- ing concentration of the adsorbate, we\ndetermine the ground states considering both single- as well as double- side\nchemisorption, which have novel chemical and electronic properties. The nature\nof the bandgap depends on the concentration of the adsorbate: for fluorination\nthe direct bandgap first decreases, and then increases while becoming indirect,\nwith increasing fluorination, while for oxidation the bandgap first increases\nand then decreases, while mostly maintaining its direct nature. Further we find\nthat the unique anisotropic free-carrier effective mass for both the electrons\nand holes, can be changed and even rotated by 90 degrees, with controlled\nchemisorption, which can be useful for exploring unusual quantum Hall effect,\nand novel electronic devices based on phosphorene."
    },
    {
        "anchor": "Effects of high order interatomic potential on elastic phonon\n  scatterings: Interatomic potentials beyond quadratic order provide scattering sources for\nphonon transport in lattice. By using a weakly-interacting interface model, we\ninvestigated the relation between the order of interatomic potential and the\nmultiple-phonon scattering process. We find that high order interatomic\npotential not only causes multiple-phonon scattering processes, but also has\nsignificant impacts on elastic phonon scattering processes. Using fourth order\npotential as an example, we show that it can significantly affects elastic\nphonon scatterings, through the formation of localized phonons. Such impact is\nclosely related to the correlations of interfacial atoms and it becomes more\nsignificant with increasing temperature. Our work suggests that it is\ninsufficient to consider only quadratic potential to investigate elastic phonon\ntransport.",
        "positive": "Magnetic Damping in Epitaxial Fe Alloyed with Vanadium and Aluminum: To develop low-moment, low-damping metallic ferromagnets for power-efficient\nspintronic devices, it is crucial to understand how magnetic relaxation is\nimpacted by the addition of nonmagnetic elements. Here, we compare magnetic\nrelaxation in epitaxial Fe films alloyed with light nonmagnetic elements of V\nand Al. FeV alloys exhibit lower intrinsic damping compared to pure Fe, reduced\nby nearly a factor of 2, whereas damping in FeAl alloys increases with Al\ncontent. Our experimental and computational results indicate that reducing the\ndensity of states at the Fermi level, rather than the average atomic number,\nhas a more significant impact in lowering damping in Fe alloyed with light\nelements. Moreover, FeV is confirmed to exhibit an intrinsic Gilbert damping\nparameter of $\\simeq$0.001, among the lowest ever reported for ferromagnetic\nmetals."
    },
    {
        "anchor": "Atomic and mesoscopic structure of Dy-based surface alloys on noble\n  metals: Surface alloys are a highly tunable class of low dimensional materials with\nthe opportunity to tune and control the spin and charge carrier functionalities\non the nanoscale. Here, we focus on the atomic and mesoscopic structural\ndetails of three distinctive binary rare-earth-noble metals (RE/NM) surface\nalloys by employing scanning tunneling microscopy (STM) and low energy electron\ndiffraction (LEED). Using Dysprosium as the guest element on fcc(111) noble\nmetal substrates, we identify the formation of non-commensurate surface alloy\nsuperstructures which exhibit homogeneous moir\\'e patterns for DyCu2/Cu (111)\nand DyAu2/Au(111), while an inhomogeneous one is found for DyAg2/Ag(111). The\nvariations in the local structure are analyzed for all three surface alloys and\nthe observed differences are discussed in the light of the lattice mismatches\nof the alloy layer with respect to the underlying substrate. For the\nparticularly intriguing case of a Dy-Ag surface alloy, the surface alloy layer\ndoes not show a uniform long-range periodic structure, but consists of local\nhexagonal tiles separated by extended domain walls. These domain walls exist to\nrelief the in-plane strain within the DyAg2 surface alloy layer. Our findings\nclearly demonstrate that surface alloying is an intriguing tool to tailor both\nthe local atomic, but also the mesoscopic moir\\'e structures of metallic\nheterostructures.",
        "positive": "Comparison of SMC and OMC results in determining the ground-state and\n  meta-stable states solutions for UO$_2$ in DFT+U method: Correct prediction of the behavior of UO2 crystal, which is an\nantiferromagnet system with strongly-correlated electrons, is possible by using\na modified density functional theory, the DFT+U method. In the context of\nDFT+U, the energy of crystal turns out to be a function with several local\nminima, the so-called meta-stable states, and the lowest energy state amongst\nthem is identified as the ground state. OMC was a method that were used in\nDFT+U to determine the ground state. Recently the SMC method was proposed which\nalso revealed the multi-minima structure of energy in the DFT+U approach and\nled to results in good agreement with experiment. In this work, we compare the\nSMC and OMC results and show that although the ground states of the two methods\nhave similar energies and geometries, the electronic structures have\nsignificant differences. Moreover, the energy band gap of SMC is in better\nagreement with experiments."
    },
    {
        "anchor": "Non-trivial topology in a layered Dirac nodal-line semimetal candidate\n  SrZnSb$_2$ with distorted Sb square nets: Dirac states hosted by Sb/Bi square nets are known to exist in the layered\nantiferromagnetic AMnX$_2$ (A = Ca/Sr/Ba/Eu/Yb, X=Sb/Bi) material family the\nspace group to be P4/nmm or I4/mmm. In this paper, we present a comprehensive\nstudy of quantum transport behaviors, angle-resolved photoemission spectroscopy\n(ARPES) and first-principles calculations on SrZnSb2, a nonmagnetic analogue to\nAMnX2, which crystallizes in the pnma space group with distorted square nets.\nFrom the quantum oscillation measurements up to 35 T, three major frequencies\nincluding F$_1$ = 103 T, F$_2$ = 127 T and F$_3$ = 160 T, are identified. The\neffective masses of the quasiparticles associated with these frequencies are\nextracted, namely, m*$_1$ = 0.1 m$_e$, m*$_2$ = 0.1 m$_e$ and m*$_3$ =\n0.09m$_e$, where m$_e$ is the free electron mass. From the three-band\nLifshitz-Kosevich fit, the Berry phases accumulated along the cyclotron orbit\nof the quasiparticles are 0.06$\\pi$, 1.2$\\pi$ and 0.74$\\pi$ for F$_1$, F$_2$\nand F$_3$, respectively. Combined with the ARPES data and the first-principles\ncalculations, we reveal that F2 and F3 are associated with the two nontrivial\nFermi pockets at the Brillouin zone edge while F1 is associated with the\ntrivial Fermi pocket at the zone center. In addition, the first-principles\ncalculations further suggest the existence of Dirac nodal line in the band\nstructure of SrZnSb$_2$.",
        "positive": "Experimental demonstration of a generalized Fourier's Law for\n  non-diffusive thermal transport: Phonon heat conduction over length scales comparable to their mean free paths\nis a topic of considerable interest for basic science and thermal management\ntechnologies. Although the failure of Fourier's law beyond the diffusive regime\nis well understood, debate exists over the proper physical description of\nthermal transport in the ballistic to diffusive crossover. Here, we derive a\ngeneralized Fourier's law that links the heat flux and temperature fields,\nvalid from ballistic to diffusive regimes and for general geometries, using the\nPeierls-Boltzmann transport equation within the relaxation time approximation.\nThis generalized Fourier's law predicts that thermal conductivity not only\nbecomes nonlocal at length scales smaller than phonon mean free paths, but also\nrequires the inclusion of an inhomogeneous nonlocal source term that has been\npreviously neglected. We demonstrate the validity of this generalized Fourier's\nlaw through direct comparison with time-domain thermoreflectance (TDTR)\nmeasurements in the nondiffusive regime without adjustable parameters.\nFurthermore, we show that interpreting experimental data without this\ngeneralized Fourier's law leads to inaccurate measurement of thermal transport\nproperties."
    },
    {
        "anchor": "Antiferroelectric negative capacitance from a structural phase\n  transition in zirconia: Crystalline materials with broken inversion symmetry can exhibit a\nspontaneous electric polarization, which originates from a microscopic electric\ndipole moment. Long-range polar or anti-polar order of such permanent dipoles\ngives rise to ferroelectricity or antiferroelectricity, respectively. However,\nthe recently discovered antiferroelectrics of fluorite structure (HfO$_2$ and\nZrO$_2$) are different: A non-polar phase transforms into a polar phase by\nspontaneous inversion symmetry breaking upon the application of an electric\nfield. Here, we show that this structural transition in antiferroelectric\nZrO$_2$ gives rise to a negative capacitance, which is promising for overcoming\nthe fundamental limits of energy efficiency in electronics. Our findings\nprovide insight into the thermodynamically 'forbidden' region of the\nantiferroelectric transition in ZrO$_2$ and extend the concept of negative\ncapacitance beyond ferroelectricity. This shows that negative capacitance is a\nmore general phenomenon than previously thought and can be expected in a much\nbroader range of materials exhibiting structural phase transitions.",
        "positive": "Electronic effects in high-energy radiation damage in iron: Electronic effects are believed to be important in high--energy radiation\ndamage processes where high electronic temperature is expected, yet their\neffects are not currently understood. Here, we perform molecular dynamics\nsimulations of high-energy collision cascades in $\\alpha$-iron using the\ncoupled two-temperature molecular dynamics (2T-MD) model that incorporates both\neffects of electronic stopping and electron-ion interaction. We subsequently\ncompare it with the model employing the electronic stopping only, and find\nseveral interesting novel insights. The 2T-MD results in both decreased damage\nproduction in the thermal spike and faster relaxation of the damage at short\ntimes. Notably, the 2T-MD model gives a similar amount of the final damage at\nlonger times, which we interpret to be the result of two competing effects:\nsmaller amount of short-time damage and shorter time available for damage\nrecovery."
    },
    {
        "anchor": "Understanding real-time time-dependent density-functional theory\n  simulations of ultrafast laser-induced dynamics in organic molecules: Real-time time-dependent density functional theory, in conjunction with the\nEhrenfest molecular dynamics scheme, is becoming a popular methodology to\ninvestigate ultrafast phenomena on the nanoscale. Thanks to recent\ndevelopments, it is also possible to explicitly include in the simulations a\ntime-dependent laser pulse, thereby accessing the transient excitation regime.\nHowever, the complexity entailed in these calculations calls for in-depth\nanalysis of the accessible and yet approximate (either \"dressed\" or \"bare\")\nquantities, in order to evaluate their ability to provide us with a realistic\npicture of the simulated processes. In this work, we analyze the ultrafast\ndynamics of three small molecules (ethylene, benzene, and thiophene) excited by\na resonant laser pulse in the framework of the adiabatic local-density\napproximation. The electronic response to the laser perturbation in terms of\ninduced dipole moment and excited-state population is compared to the results\ngiven by an exactly solvable two-level model. In this way, we can interpret the\ncharge-carrier dynamics in terms of simple estimators, such as the number of\nexcited electrons. From the computed transient absorption spectra we unravel\nthe appearance of nonlinear effects such as excited-state absorption and\nvibronic coupling. In this way, we observe that the laser excitation affects\nthe vibrational spectrum by enhancing the anharmonicities therein while the\ncoherent vibrational motion contributes to stabilize the electronic excitation\nalready within a few tens of femtoseconds.",
        "positive": "Ultrafast Radiative Heat Transfer: Light absorption in conducting materials produces heating of their conduction\nelectrons, followed by relaxation into phonons within picoseconds, and\nsubsequent diffusion into the surrounding media over longer timescales. This\nconventional picture of optical heating is supplemented by radiative cooling,\nwhich typically takes place at an even lower pace, only becoming relevant for\nstructures held in vacuum or under extreme conditions of thermal isolation.\nHere we reveal an ultrafast radiative cooling regime between neighboring\nplasmon-supporting graphene nanostructures in which noncontact heat transfer\nbecomes a dominant channel. We predict that >50% of the electronic heat energy\ndeposited on a graphene disk can be transferred to a neighboring nanoisland\nwithin a femtosecond timescale. This phenomenon is facilitated by the\ncombination of low electronic heat capacity and large plasmonic field\nconcentration displayed by doped graphene. Similar effects should take place in\nother van der Waals materials, thus opening an unexplored avenue toward\nefficient heat management in ultrathin nanostructures."
    },
    {
        "anchor": "Phase Object Reconstruction for 4D-STEM using Deep Learning: In this study we explore the possibility to use deep learning for the\nreconstruction of phase images from 4D scanning transmission electron\nmicroscopy (4D-STEM) data. The process can be divided into two main steps.\nFirst, the complex electron wave function is recovered for a convergent beam\nelectron diffraction pattern (CBED) using a convolutional neural network (CNN).\nSubsequently a corresponding patch of the phase object is recovered using the\nphase object approximation (POA). Repeating this for each scan position in a\n4D-STEM dataset and combining the patches by complex summation yields the full\nphase object. Each patch is recovered from a kernel of 3x3 adjacent CBEDs only,\nwhich eliminates common, large memory requirements and enables live processing\nduring an experiment. The machine learning pipeline, data generation and the\nreconstruction algorithm are presented. We demonstrate that the CNN can\nretrieve phase information beyond the aperture angle, enabling super-resolution\nimaging. The image contrast formation is evaluated showing a dependence on\nthickness and atomic column type. Columns containing light and heavy elements\ncan be imaged simultaneously and are distinguishable. The combination of\nsuper-resolution, good noise robustness and intuitive image contrast\ncharacteristics makes the approach unique among live imaging methods in\n4D-STEM.",
        "positive": "Magnetotransport near a quantum critical point in a simple metal: We use geometric considerations to study transport properties, such as the\nconductivity and Hall coefficient, near the onset of a nesting-driven spin\ndensity wave in a simple metal. In particular, motivated by recent experiments\non vanadium-doped chromium, we study the variation of transport coefficients\nwith the onset of magnetism within a mean-field treatment of a model that\ncontains nearly nested electron and hole Fermi surfaces. We show that most\ntransport coefficients display a leading dependence that is linear in the\nenergy gap. The coefficient of the linear term, though, can be small. In\nparticular, we find that the Hall conductivity $\\sigma_{xy}$ is essentially\nunchanged, due to electron-hole compensation, as the system goes through the\nquantum critical point. This conclusion extends a similar observation we made\nearlier for the case of completely flat Fermi surfaces to the immediate\nvicinity of the quantum critical point where nesting is present but not\nperfect."
    },
    {
        "anchor": "Transient photon echoes from donor-bound excitons in ZnO epitaxial\n  layers: The coherent optical response from 140~nm and 65~nm thick ZnO epitaxial\nlayers is studied using transient four-wave-mixing spectroscopy with picosecond\ntemporal resolution. Resonant excitation of neutral donor-bound excitons\nresults in two-pulse and three-pulse photon echoes. For the donor-bound A\nexciton (D$^0$X$_\\text{A}$) at temperature of 1.8~K we evaluate optical\ncoherence times $T_2=33-50$~ps corresponding to homogeneous linewidths of\n$13-19~\\mu$eV, about two orders of magnitude smaller as compared with the\ninhomogeneous broadening of the optical transitions. The coherent dynamics is\ndetermined mainly by the population decay with time $T_1=30-40$~ps, while pure\ndephasing is negligible in the studied high quality samples even for strong\noptical excitation. Temperature increase leads to a significant shortening of\n$T_2$ due to interaction with acoustic phonons. In contrast, the loss of\ncoherence of the donor-bound B exciton (D$^0$X$_\\text{B}$) is significantly\nfaster ($T_2=3.6$~ps) and governed by pure dephasing processes.",
        "positive": "Single-layer Graphene Nearly 100% Covering an Entire Substrate: Graphene has recently attracted a great deal of interest in both academia and\nindustry because of its unique electronic and optical properties [1,2], as well\nas its chemical, thermal, and mechanical properties. The superb characteristics\nof graphene make this material one of the most promising candidates for various\napplications, such as ultrafast electronic circuits [1] and photodetectors [2],\nclean and renewable energy [3], and rapid single-molecule DNA sequencing [4,5].\nThe electronic properties of the graphene system rely heavily on the number of\ngraphene layers [6] and effects on the coupling with the underlying substrate.\nGraphene can be produced by mechanical exfoliation of graphite, solution\napproaches [7,8], thermal decomposition of SiC [9,10], and chemical vapor\ndeposition/segregation on catalytic metals [11-17]. Despite significant\nprogress in graphene synthesis, production with fine control over the thickness\nof the film remains a considerable challenge. Here, we report on the synthesis\nof nearly 100% coverage of single-layer graphene on a Ni(111) surface with\ncarbon atoms diffused from a highly orientated pyrolytic graphite (HOPG)\nsubstrate. Our results demonstrate how fine control of thickness and structure\ncan be achieved by optimization of equilibrium processes of carbon diffusion\nfrom HOPG, segregation from Ni, and carbon diffusion at a Ni surface. Our\nmethod represents a significant step toward the scalable synthesis of graphene\nfilms with high structural qualities and finely controlled thicknesses and\ntoward realizing the unique properties of graphene."
    },
    {
        "anchor": "Kinetics of photoinduced ordering in azo-dye films: two-state and\n  diffusion models: We study the kinetics of photoinduced ordering in the azo-dye SD1\nphotoaligning layers and present the results of modeling performed using two\ndifferent phenomenological approaches. A phenomenological two state model is\ndeduced from the master equation for an ensemble of two-level molecular\nsystems. Using an alternative approach, we formulate the two-dimensional (2D)\ndiffusion model as the free energy Fokker-Planck equation simplified for the\nlimiting regime of purely in-plane reorientation. The models are employed to\ninterpret the irradiation time dependence of the absorption order parameters\nextracted from the available experimental data by using the exact solution to\nthe light transmission problem for a biaxially anisotropic absorbing layer. The\ntransient photoinduced structures are found to be biaxially anisotropic whereas\nthe photosteady and the initial states are uniaxial.",
        "positive": "Electron-irradiation-facilitated production of chemically homogenized\n  nanotwins in nanolaminated carbides: Twin boundaries have been exploited to stabilize ultrafine grains and improve\nthe mechanical properties of nanomaterials. The production of twin boundaries\nand nanotwins is however prohibitively challenging in carbide ceramics. Using\nscanning transmission electron microscopes as a unique platform for\natomic-scale structure engineering, we demonstrate that twin platelets could be\nproduced in carbides by engineering antisite defects. Antisite defects at metal\nsites in various layered ternary carbides are collectively and controllably\ngenerated and the metal elements are homogenized by electron irradiation, which\ntransforms the twin-like lamellae into nanotwin platelets. Accompanying the\nchemical homogenization, {\\alpha}-Ti3AlC2 transforms to unconventional\n\\b{eta}-Ti3AlC2. The chemical homogeneity and the width of the twin platelets\ncan be tuned by the dose and energy of bombarding electrons. Chemically\nhomogenized nanotwins can boost the hardness by ~45%. Our results provide a new\nway to produce ultrathin (<5 nm) nanotwin platelets in scientifically and\ntechnologically important carbide materials and showcase the feasibility of\ndefect engineering by an angstrom-sized electron probe."
    },
    {
        "anchor": "Role of force-constant difference in phonon scattering by\n  nano-precipitates in PbTe: We study the effect of nanoscale precipitates on lattice thermal conduction\nin thermoelectric PbTe using a combination of ab-initio phonon calculations and\nmolecular dynamics. We take into account the effects of mass difference and\nchange in force constants, and find an enhanced influence of the latter with\nincreased precipitate concentration. As a consequence, our inclusion of the\nchange in force constants in the calculation affords a smaller predicted\noptimal nano-precipitate size that minimizes the thermal conductivity. These\nresults suggest that the phonon scattering by nanoprecipitates in\nthermoelectric composites could be stronger than previously thought.",
        "positive": "Effect of Mg-Al insertion on magnetotransport properties in epitaxial\n  Fe/sputter-deposited $MgAl_{2}O_{4}$/Fe(001) magnetic tunnel junctions: We investigated the effect of a Mg-Al layer insertion at the bottom interface\nof epitaxial Fe/$MgAl_{2}O_{4}$/Fe(001) magnetic tunnel junctions (MTJs) on\ntheir spin-dependent transport properties. The tunnel magnetoresistance (TMR)\nratio and differential conductance spectra for the parallel magnetic\nconfiguration exhibited clear dependence on the inserted Mg-Al thickness. A\nslight Mg-Al insertion (thickness < 0.1 nm) was effective for obtaining a large\nTMR ratio above 200% at room temperature and observing a distinct local minimum\nstructure in conductance spectra. In contrast, thicker Mg-Al (> 0.2 nm) induced\na reduction of TMR ratios and featureless conductance spectra, indicating a\ndegradation of the bottom-Fe/$MgAl_{2}O_{4}$ interface. Therefore, a minimal\nMg-Al insertion was found to be effective to maximize the TMR ratio for a\nsputtered $MgAl_{2}O_{4}$-based MTJ."
    },
    {
        "anchor": "Fast Pixelated Detectors in Scanning Transmission Electron Microscopy.\n  Part II: Post Acquisition Data Processing, Visualisation, and Structural\n  Characterisation: Fast pixelated detectors incorporating direct electron detection (DED)\ntechnology are increasingly being regarded as universal detectors for scanning\ntransmission electron microscopy (STEM), capable of imaging under multiple\nmodes of operation. However, several issues remain around the post acquisition\nprocessing and visualisation of the often very large multidimensional STEM\ndatasets produced by them. We discuss these issues and present open source\nsoftware libraries to enable efficient processing and visualisation of such\ndatasets. Throughout, we provide examples of the analysis methodologies\npresented, utilising data from a 256$\\times$256 pixel Medipix3 hybrid DED\ndetector, with a particular focus on the STEM characterisation of the\nstructural properties of materials. These include the techniques of virtual\ndetector imaging; higher order Laue zone analysis; nanobeam electron\ndiffraction; and scanning precession electron diffraction. In the latter, we\ndemonstrate nanoscale lattice parameter mapping with a fractional precision\n$\\le 6\\times10^{-4}$ (0.06%).",
        "positive": "Weakly-correlated nature of ferromagnetism in non symmorphic CrO$_2$\n  revealed by bulk-sensitive soft X ray ARPES: Chromium dioxide CrO$_2$ belongs to a class of materials called ferromagnetic\nhalf-metals, whose peculiar aspect is to act as a metal in one spin orientation\nand as semiconductor or insulator in the opposite one. Despite numerous\nexperimental and theoretical studies motivated by technologically important\napplications of this material in spintronics, its fundamental properties such\nas momentum resolved electron dispersions and Fermi surface have so far\nremained experimentally inaccessible due to metastability of its surface that\ninstantly reduces to amorphous Cr$_2$O$_3$. In this work, we demonstrate that\ndirect access to the native electronic structure of CrO$_2$ can be achieved\nwith soft-X-ray angle-resolved photoemission spectroscopy whose large probing\ndepth penetrates through the Cr$_2$O$_3$ layer. For the first time the\nelectronic dispersions and Fermi surface of CrO$_2$ are measured, which are\nfundamental prerequisites to solve the long debate on the nature of electronic\ncorrelations in this material. Since density functional theory augmented by a\nrelatively weak local Coulomb repulsion gives an exhaustive description of our\nspectroscopic data, we rule out strong-coupling theories of CrO$_2$. Crucial\nfor the correct interpretation of our experimental data in terms of the valence\nband dispersions is the understanding of a non-trivial spectral response of\nCrO$_2$ caused by interference effects in the photoemission process originating\nfrom the non-symmorphic space group of the rutile crystal structure of CrO$_2$."
    },
    {
        "anchor": "Machine Learning Based Approach to Predict Ductile Damage Model\n  Parameters for Polycrystalline Metals: Damage models for ductile materials typically need to be parameterized, often\nwith the appropriate parameters changing for a given material depending on the\nloading conditions. This can make parameterizing these models computationally\nexpensive, since an inverse problem must be solved for each loading condition.\nUsing standard inverse modeling techniques typically requires hundreds or\nthousands of high-fidelity computer simulations to estimate the optimal\nparameters. Additionally, the time of a human expert is required to set up the\ninverse model. Machine learning has recently emerged as an alternative approach\nto inverse modeling in these settings, where the machine learning model is\ntrained in an offline manner and new parameters can be quickly generated on the\nfly, after training is complete. This work utilizes such a workflow to enable\nthe rapid parameterization of a ductile damage model called TEPLA with a\nmachine learning inverse model. The machine learning model can efficiently\nestimate the model parameters much faster, as compared to previously employed\nmethods, such as Bayesian calibration. The results demonstrate good accuracy on\na synthetic test dataset and is validated against experimental data.",
        "positive": "Substrate effect and nanoindentation fracture toughness based on pile up\n  and failure: The effect of substrate was studied using nanoindentation on thin films. Soft\nfilms on hard substrate showed more pile up than usual which was attributed to\nthe dislocation pile up at the film substrate interface. The effect of tip\nblunting on the load depth and hardness plots of nanoindentation was shown. The\nexperimental date of variation of Vickers hardness with film thickness and\nloads were fitted and new parameters were analyzed. The delaminated area was\nanalyzed using geometrical shapes using optical view of the failure region\nalong with the load displacement Indentation fracture using Nanoindentation\nusing Berkovich indenter has been studied. Indentation fracture toughness (KR)\nwas analyzed based on computational programs. The contact mechanics during\nnanoindentation was studied with parameters related to indenter shape and tip\nsharpness. Elastic, plastic and total energies were computationally determined.\nThe energy difference was related to shear stress being generated with elastic\nto plastic transition. Change in the nature of residual stress was related to\nfilm thickness."
    },
    {
        "anchor": "Simulating the nanomechanical response of cyclooctatetraene molecules on\n  a graphene device: We investigate the atomic and electronic structures of cyclooctatetraene\n(COT) molecules on graphene and analyze their dependence on external gate\nvoltage using first-principles calculations. The external gate voltage is\nsimulated by adding or removing electrons using density functional theory (DFT)\ncalculations. This allows us to investigate how changes in carrier density\nmodify the molecular shape, orientation, adsorption site, diffusion barrier,\nand diffusion path. For increased hole doping COT molecules gradually change\ntheir shape to a more flattened conformation and the distance between the\nmolecules and graphene increases while the diffusion barrier drastically\ndecreases. For increased electron doping an abrupt transition to a planar\nconformation at a carrier density of -8$\\times$10$^{13}$ e/cm$^2$ is observed.\nThese calculations imply that the shape and mobility of adsorbed COT molecules\ncan be controlled by externally gating graphene devices.",
        "positive": "Influence of lattice orientation on growth and structure of graphene on\n  Cu(001): We have used low-energy electron microscopy and diffraction to examine the\nsignificance of lattice orientation in graphene growth on Cu(001). Individual\ngraphene domains undergo anisotropic growth on the Cu surface, and develop into\nlens shapes with their long axes roughly aligned with the Cu<100> in-plane\ndirections. The long axis of a lens-shaped domain is only rarely oriented along\na C<11> direction, suggesting that carbon attachment at \"zigzag\" graphene\nisland edges is unfavorable. A kink-mediated adatom attachment process is\nconsistent with the behavior observed here and reported in the literature. The\ndetails of the ridged moire pattern formed by the superposition of the graphene\nlattice on the (001) Cu surface also evolve with the graphene lattice\norientation, and are predicted well by a simple geometric model. Managing the\nkink-mediated growth mode of graphene on Cu(001) will be necessary for the\ncontinued improvement of this graphene synthesis technique."
    },
    {
        "anchor": "Structural and magnetic properties of hexagonal perovskites\n  La1.2Sr2.7MO7+d (M=Ru,Ir): The structures of the new compound La1.2Sr2.7IrO7+d and the recently\ndiscovered La1.2Sr2.7RuO7+d have been solved using a combination of X-ray and\nneutron diffraction. Both compounds crystallize in the trigonal space group\nR-3m and contain isolated MO6 (M=Ru,Ir) octahedra, which are arranged in\nwell-defined layers. Results of the magnetic susceptibility and XANES\nmeasurements show that the transition metal cations are in a pentavalent state.\nWhile in La1.2Sr2.7RuO7+d an antiferromagnetic interaction between the Ru5+\nions is found, La1.2Sr2.7IrO7+d shows a very small temperature-independent\nparamagnetism down to 1.8 K due to the strong spin-orbit coupling\ncharacteristic for the 5d element iridium.",
        "positive": "Ab initio calculations of inelastic losses and optical constants: Ab initio approaches are introduced for calculations of inelastic losses and\nvibrational damping in core level x-ray and electron spectroscopies. From the\ndielectric response function we obtain system-dependent self-energies,\ninelastic mean free paths, and losses due to multiple-electron excitations,\nwhile from the dynamical matrix we obtain phonon spectra and Debye-Waller\nfactors. These developments yield various spectra and optical constants from\nthe UV to x-ray energies in aperiodic materials, and significantly improve both\nthe near edge and extended fine structure."
    },
    {
        "anchor": "Two-stage Hydrogen Compression Using Zr-based Metal Hydrides: Zr-based AB2-Laves phase type alloys containing the same type of A and B\nmetals, have been prepared from pure elements by melting and subsequent\nre-melting under argon atmosphere by using a HF-induction levitation furnace.\nCharacterization of the alloys has resulted from powder X-Ray Diffraction (XRD)\nmeasurements and SEM/EDX analyses. Systematic PCI\n(Pressure-Composition-Isotherms) measurements have been recorded at 20 and 90\noC, using a high-pressure Sievert's type apparatus. The purpose of this study\nis to find a series of alloys promptly forming metal hydrides (MH) with\nsuitable properties in order to build a MH-based hydrogen compressor, working\nin the same way between 20 and ~100 oC.",
        "positive": "A-type Antiferromagnetic order in MnBi4Te7 and MnBi6Te10 single crystals: MnBi$_4$Te$_{7}$ and MnBi$_6$Te$_{10}$ are two members with n=2 and 3 in the\nfamily of MnBi$_{2n}$Te$_{3n+1}$ where the n=1 member, MnBi$_2$Te$_{4}$, has\nbeen intensively investigated as the first intrinsic antiferromagnetic\ntopological insulator. Here we report the A-type antiferromagnetic order in\nthese two compounds by measuring magnetic properties, electrical and thermal\ntransport, specific heat, and single crystal neutron diffraction. Both\ncompounds order into an A-type antiferromagnetic structure as does\nMnBi$_2$Te$_{4}$ with ferromagnetic planes coupled antiferromagnetically along\nthe crystallographic \\textit{c} axis. While no evidence for any in-plane\nordered moment is found for MnBi$_2$Te$_{4}$ or MnBi$_6$Te$_{10}$, weak\nreflections at half-L positions along the [0 0 L] direction are observed for\nMnBi$_4$Te$_{7}$ suggesting an in-plane ordered moment around 0.15$\\mu_{B}$/Mn.\nThe ordering temperature, T$_N$, is 13\\,K for MnBi$_4$Te$_{7}$ and 11\\,K for\nMnBi$_6$Te$_{10}$. The magnetic order is also manifested in the anisotropic\nmagnetic properties. For both compounds, the interlayer coupling is weak and a\nspin flip transition occurs when a magnetic field of around 1.6\\,kOe is applied\nalong the \\textit{c}-axis at 2\\,K. As observed in MnBi$_2$Te$_4$, when cooling\nacross T$_N$, no anomaly was observed in the temperature dependence of\nthermopower. On the other hand, critical scattering effects are observed in\nthermal conductivity although the effect is less pronounced than that in\nMnBi$_2$Te$_{4}$."
    },
    {
        "anchor": "Annealing induced colossal magnetocapacitance and colossal\n  magnetoresistance in In-doped CdCr2S4: The correlation between colossal magnetocapacitance (CMC) and colossal\nmagnetoresistance (CMR) in CdCr2S4 system has been revealed. The CMC is induced\nin polycrystalline Cd0.97In0.03Cr2S4 by annealing in cadmium vapor. At the same\ntime, an insulator-metal transition and a concomitant CMR are observed near the\nCurie temperature. In contrast, after the same annealing treatment, CdCr2S4\ndisplays a typical semiconductor behavior and does not show magnetic field\ndependent dielectric and electric transport properties. The simultaneous\noccurrence or absence of CMC and CMR effects implies that the CMC in the\nannealed Cd0.97In0.03Cr2S4 could be explained qualitatively by a combination of\nCMR and Maxwell-Wagner effect.",
        "positive": "Influence of inter-sublattice coupling on the terahertz nutation spin\n  dynamics in antiferromagnets: Spin nutation resonance has been well-explored in one-sublattice\nferromagnets. Here, we investigate the spin nutation in two-sublattice\nantiferromagnets as well as, for comparison, ferrimagnets with inter-and\nintra-sublattice nutation coupling. In particular, we derive the susceptibility\nof the two-sublattice magnetic system in response to an applied external\nmagnetic field. To this end, the antiferromagnetic and ferrimagnetic (sub-THz)\nprecession and THz nutation resonance frequencies are calculated. Our results\nshow that the precession resonance frequencies and effective damping decrease\nwith intra-sublattice nutation coupling, while they increase with inter\n-sublattice nutation in an antiferromagnet. However, we find that the THz\nnutation resonance frequencies decrease with both the intra-and\ninter-sublattice nutation couplings. For ferrimagnets, conversely, we calculate\ntwo nutation modes with distinct frequencies, unlike antiferromagnets. The\nexchange-like precession resonance frequency of ferrimagnets decreases with\nintra-sublattice nutation coupling and increases with inter-sublattice nutation\ncoupling, like antiferromagnets, but the ferromagnetic-like precession\nfrequency of ferrimagnets is practically invariant to the intra and\ninter-sublattice nutation couplings."
    },
    {
        "anchor": "Monte Carlo simulations of ferromagnetism in p-CdMnTe quantum wells: Monte Carlo simulations, in which the Schrodinger equation is solved at each\nMonte Carlo sweep, are employed to assess the influence of magnetization\nfluctuations,short-range antiferromagnetic interactions, disorder, magnetic\npolaron formation, and spin-Peierls instability on the carrier-mediated Ising\nferromagnetism in two-dimensional electronic systems. The determined critical\ntemperature and hysteresis are affected in a nontrivial way by the\nantiferromagnetic interactions. The findings explain striking experimental\nresults for modulation-doped p-CdMnTe quantum wells.",
        "positive": "A possible model to high TC ferromagnetism in Gallium Manganese Nitrides\n  based on resonation properties of impurities in semiconductors: The high TC ferromagnetism in (Ga,Mn)N were observed and almost all results\nare approximately similar to the experimental results in (Ga,Mn)As except the\nvalue of TC. Though all standard experiments on magnetism clearly support the\nresults, the value is unexpectedly high. This work present and discuss the\npossibility of high TC ferromagnetism, after brief review of the experimental\nresults. The key speculation to Bosonization method in three dimensions is\nresembled with the problems in Anderson localization."
    },
    {
        "anchor": "Epitaxy enhancement in oxide/tungsten heterostructures by harnessing the\n  interface adhesion: The conditions whereby epitaxy is achieved are commonly believed to be mostly\ngoverned by misfit strain. We report on a systematic investigation of growth\nand interface structure of single crystalline tungsten thin films on two\ndifferent metal oxide substrates, Al$_{2}$O$_{3}$ ($11\\bar{2}0$) and MgO\n($001$). We demonstrate that despite a significant mismatch, enhanced crystal\nquality is observed for tungsten grown on the sapphire substrates. This is\npromoted by stronger adhesion and chemical bonding with sapphire compared to\nmagnesium oxide, along with the restructuring of the tungsten layers close to\nthe interface. The latter is supported by ab initio calculations using density\nfunctional theory. Finally, we demonstrate the growth of magnetic\nheterostructures consisting of high-quality tungsten layers in combination with\nferromagnetic CoFe layers, which are relevant for spintronic applications.",
        "positive": "Electricity generated from Ambient Heat by Pencils: The idea of generating electricity from ambient heat has significant meanings\nfor both science and engineering. Here, we present an interesting idea of using\npencil leads, which are made of graphite and clay, to generate electricity from\nthe thermal motion of ions in aqueous electrolyte solution at room temperature.\nWhen two pencil leads were placed in parallel in the solutions, output power of\n0.655, 1.023, 1.023 and 1.828 nW were generated in 3 M KCl, NaCl, NiCl2 and\nCuCl2 solutions, respectively. Besides, we also demonstrate that two pieces of\nreduced graphene oxide films and /or few-layer graphene films can generate much\nmore electricity when dipped into the solutions, while there was no electrodes\ncontact with the solution. This finding further verified that the electricity\nwas not resulted from the chemical reaction between the electrodes and the\nsolutions. The results also demonstrate that ambient thermal energy can be\nharvested with low dimensional materials, such as graphene, or with the surface\nof solid material without the presence of temperature gradient. However, the\nmechanism is still unclear."
    },
    {
        "anchor": "Polar Behavior in a Magnetic Perovskite Via A-Site Disorder: We elucidate a mechanism for obtaining polar behavior in magnetic perovskites\nbased on A-site disorder and demonstrate this mechanism by density functional\ncalculations for the double perovskite (La,Lu)MnNiO$_6$ with Lu concentrations\nat and below 50%. We show that this material combines polar behavior and\nferromagnetism. The mechanism is quite general and may be applicable to a wide\nrange of magnetic perovskites.",
        "positive": "Magnetism in amorphous carbon: We investigate magnetism in amorphous carbon as suggested by the recently\nreported ferromagnetism in a new form of amorphous carbon. We use spin\nconstrained first-principles simulations to obtain amorphous carbon structures\nwith the desired magnetization. We show that the existence of $sp^2$-like\n3-fold coordinated carbon atoms plays an important role in obtaining magnetism\nin amorphous carbon. The detailed geometries of 3-fold carbon atoms induce the\nmagnetic order in amorphous carbon."
    },
    {
        "anchor": "Development of nanowire devices with quantum functionalities: Silicon has dominated the microelectronics industry for the last 50 years.\nWith its zero nuclear spin isotope (28Si) and low spin orbit coupling, it is\nbelieved that silicon can become an excellent host material for an entirely new\ngeneration of devices that operate under the laws of quantum mechanics [1}.\nSemiconductor nanowires however, offer huge potential as the next building\nblocks of nano-devices due to their one-dimensional structure and properties\n[2]. We describe a fabrication process to prepare doped vapor-liquid-solid\n(VLS) grown silicon nanowire samples in a 2- and 4-terminal measurement setup\nfor electrical characterisation.",
        "positive": "Unusual Ferroelectricity Induced by the Jahn-Teller Effect: A Case Study\n  on Lacunar Spinel Compounds: The Jahn-Teller effect refers to the symmetry-lowering geometrical distortion\nin a crystal (or non-linear molecule) due to the presence of a degenerate\nelectronic state. Usually, the Jahn-Teller distortion is not polar. Recently,\nGaV4S8 with the lacunar spinel structure was found to undergoes a Jahn-Teller\ndistortion from cubic to ferroelectric rhombohedral structure at TJT = 38K. In\nthis work, we carry out a general group theory analysis to show how and when\nthe Jahn-Teller effect gives rise to ferroelectricity. On the basis of this\ntheory, we find that the ferroelectric Jahn-Teller distort in GaV4S8 is due to\nthe non-centrosymmetric nature of the parent phase and strong electron-phonon\ninteraction related to two low-energy T2 phonon modes. Interestingly, GaV4S8 is\nnot only ferroelectric, but also ferromagnetic with the magnetic easy axis\nalong the ferroelectric direction. This suggests that GaV4S8 is a multiferroic\nin which an external electric field may control its magnetization direction.\nOur study not only explains the Jahn-Teller physics in GaV4S8, but also paves a\nnew way for searching and designing new ferroelectrics and multiferroics."
    },
    {
        "anchor": "Spiral ground state against ferroelectricity in the frustrated magnet\n  BiMnFe2O6: The spiral magnetic structure and underlying spin lattice of BiMnFe2O6 are\ninvestigated by low-temperature neutron powder diffraction and density\nfunctional theory band structure calculations. In spite of the random\ndistribution of the Mn3+ and Fe3+ cations, this compound undergoes a transition\ninto an incommensurate antiferromagnetically ordered state below TN ~ 220 K.\nThe magnetic structure is characterized by the propagation vector k=[0,beta,0]\nwith beta ~ 0.14 and the P22_12_11'(0 \\beta 0)0s0s magnetic superspace\nsymmetry. It comprises antiferromagnetic helixes propagating along the b-axis.\nThe magnetic moments lie in the ac plane and rotate about pi*(1+beta) ~ 204.8\ndeg angle between the adjacent magnetic atoms along b. The spiral magnetic\nstructure arises from the peculiar frustrated arrangement of exchange couplings\nin the ab plane. The antiferromagnetic coupling along the c-axis leads to the\ncancellation of electric polarization, and results in the lack of\nferroelectricity in BiMnFe2O6.",
        "positive": "Revisiting the transient coarsening kinetics: a new framework in the\n  Lifshitz-Slyozov-Wagner space: Phase coarsening is a fundamental process of microstructure evolution in\nmultiphase materials. A thorough understanding of its kinetics is of great\nsignificance for material processing and performance. Generally, coarsening can\nbe divided into the transient stage and the steady stage. Compared with steady\ncoarsening kinetics, the current understanding of transient coarsening is\nrather limited and contradictory. In the present work, a new framework in the\ndimensionless Lifshitz-Slyozov-Wagner space is developed to study transient\ncoarsening kinetics co-controlled by interface migration/reaction and matrix\ndiffusion, where the dynamic equation for individual particles is derived from\nthe thermodynamic extremal principle."
    },
    {
        "anchor": "Graphene on silicon: effects of the silicon surface orientation on the\n  work function and carrier density of graphene: Density functional theory has been employed to study graphene on the (111),\n(100) and (110) surfaces of silicon (Si) substrates. There are several\ninteresting findings. First, carbon atoms in graphene form covalent bonds with\nSi atoms, when placed close enough on Si (111) and (100) surfaces, but not on\nthe (110) surface. The presence of a Si (111) surface shifts the Fermi level of\ngraphene into its conduction band, resulting in an increase of the work\nfunction by 0.29 eV and of the electron density by three orders of magnitude.\nThe carrier density of graphene can also be increased by eighty times on a Si\n(100) substrate without doping, due to the modification of the density of\nstates near the Dirac point. No interfacial covalent bond can be formed on Si\n(110). These striking effects that different orientations of a silicon\nsubstrate can have on the properties of graphene are related to the surface\ndensity of the silicon surface. Applying the results to a real device of a\nspecific orientation requires further consideration of surface reconstructions,\nlattice mismatch, temperature, and environmental effects.",
        "positive": "Raman spectroscopy as a versatile tool for studying the properties of\n  graphene: Raman spectroscopy is an integral part of graphene research. It is used to\ndetermine the number and orientation of layers, the quality and types of edge,\nand the effects of perturbations, such as electric and magnetic fields, strain,\ndoping, disorder and functional groups. This, in turn, provides insight into\nall $sp^2$-bonded carbon allotropes, because graphene is their fundamental\nbuilding block. Here we review the state of the art, future directions and open\nquestions in Raman spectroscopy of graphene. We describe essential physical\nprocesses whose importance has only recently been recognized, such as the\nvarious types of resonance at play, and the role of quantum interference. We\nupdate all basic concepts and notations, and propose a terminology that is able\nto describe any result in literature. We finally highlight the potential of\nRaman spectroscopy for layered materials other than graphene."
    },
    {
        "anchor": "Structural phase transformations in metallic grain boundaries: Structural transformations at interfaces are of profound fundamental interest\nas complex examples of phase transitions in low-dimensional systems. Despite\ndecades of extensive research, no compelling evidence exists for structural\ntransformations in high-angle grain boundaries in elemental systems. Here we\nshow that the critical impediment to observations of such phase transformations\nin atomistic modeling has been rooted in inadequate simulation methodology. The\nproposed new methodology allows variations in atomic density inside the grain\nboundary and reveals multiple grain boundary phases with different atomic\nstructures. Reversible first-order transformations between such phases are\nobserved by varying temperature or injecting point defects into the boundary\nregion. Due to the presence of multiple metastable phases, grain boundaries can\nabsorb significant amounts of point defects created inside the material by\nprocesses such as irradiation. We propose a novel mechanism of radiation damage\nhealing in metals which may guide further improvements in radiation resistance\nof metallic materials through grain boundary engineering.",
        "positive": "Electrocrystallization of Supercooled Water in Confinement: The paper discusses the features of supercooled water thin film of width\n$d=3.97$~nm contained by the perfect graphene layers and crystallizing under\nexternal stationary electric field. It was found that the electric field\napplied perpendicular to graphene layers impedes structural ordering, while the\nelectric field applied in lateral direction contributes to formation of the\ncubic ice ($Ic$) phase, which is thermodynamically less stable compared to the\nhexagonal ice ($Ih$) phase. It is shown that the growth of the $Ic$ crystalline\nphase occurs without formation of intermediate crystalline phases. It was found\nthat the crystallization rate depends strongly on the magnitude of the applied\nelectric field. In particular, the processes of full electrocrystallization of\nthe system do not appear over simulation time scale ($\\sim 40$~ns) if the\nelectric field of the magnitude less than $0.07~\\rm{V/\\AA}$ is applied."
    },
    {
        "anchor": "Skyrmionic magnetization configurations at chiral magnet/ferromagnet\n  heterostructures: We consider magnetization configurations at chiral magnet (CM)/ferromagnet\n(FM) heterostructures. In the CM, magnetic skyrmions and spin helices emerge\ndue to the Dzyaloshinskii-Moriya interaction, which then penetrate into the\nadjacent FM. However, because the non-uniform magnetization structures are\nenergetically unfavorable in the FM, the penetrated magnetization structures\nare deformed, resulting in exotic three-dimensional configurations, such as\nskyrmion cones, sideways skyrmions, and twisted helices and skyrmions. We\ndiscuss the stability of possible magnetization configurations at the CM/FM and\nCM/FM/CM hybrid structures within the framework of the variational method, and\nfind that various magnetization configurations appear in the ground state, some\nof which cause nontrivial emergent magnetic field.",
        "positive": "Systematic Investigation of the Intrinsic Channel Properties and Contact\n  Resistance of Monolayer and Multilayer Graphene FET: The intrinsic channel properties of monolayer and multilayer graphene were\nsystematically investigated as a function of layer number by the exclusion of\ncontact resistance using four-probe measurements. We show that the continuous\nchange in normalized sheet resistivity from graphite to a bilayer graphene is\ngoverned by one unique property, i.e., the band overlap, which markedly\nincreases from 1 meV for a bilayer graphene to 11 meV for eight layers and\neventually reaches 40 meV for graphite. The monolayer graphene, however, showed\na deviation in temperature dependence due to a peculiar linear dispersion.\nAdditionally, contact resistivity was extracted for the case of typical Cr/Au\nelectrodes. The observed high contact resistivity, which varies by three orders\nof magnitude (from ~103 to 106 Ohm micron), might significantly mask the\noutstanding performance of the monolayer graphene channel, suggesting its\nimportance in future research."
    },
    {
        "anchor": "Absence of long-range Ni/Mn ordering in ferromagnetic La2NiMnO6 thin\n  films: Epitaxial La2NiMnO6 thin films have been grown on (001)-oriented SrTiO3 using\nthe PLD technique. The thin films are semiconducting and FM with a TC close to\n270K, a coercive field of 920Oe, and a saturation magnetization of 5muB per\nf.u. TEM, conducted at RT, reveals a majority phase having \"I-centered\"\nstructure with a=c=1.4asub and b=2asub along with a minority phase-domains\nhaving \"P-type\" structure (asub being the lattice parameter of the perovskite\nstructure). A discusion on the presence of Ni/Mn long-range ordering, in light\nof recent literature on double perovskites La2NiMnO6 is presented.",
        "positive": "Orbital-selective behavior in Y5Mo2O12 and (Cd,Zn)V2O4: We present two examples of the real materials, which show orbital-selective\nbehavior. In both compounds a part of the electrons is localized on the\nmolecular orbitals, which lead to a significant reduction of the magnetic\nmoment on the transition metal ion."
    },
    {
        "anchor": "A New Vortex Solution for Two-Component Nonlinear Schroedinger Equation\n  in Anisotropic Optical Media: A theoretical study is given of a new type of optical vortex in nonlinear\nanisotropic media. This is realized as a special solution of the two-component\nnon-linear Schroedinger equation. The vortex is inherent in the spin texture\nthat is caused by an anisotropy of dielectric tensor, for which a role of spin\nis played by the Stokes vector (or pseudo-spin). By using the effective\nLagrangian for the pseudo-spin field, we give an explicit form for the vortex\nsolution for the case of two types of optical anisotropy; that is, nonlinear\ncounterpart of birefringence giving rise to the Faraday and Cotton-Mouton\neffects. We also examine the evolution equation of the new vortex with respect\nto the propagation direction.",
        "positive": "Mechanics of Topologically Interlocked Material Systems under Point\n  Load: Archimedean and Laves Tiling: Topologically interlocked material systems are two-dimensional assemblies of\nunit elements from which no element can be removed from the assembly without\ndisassembly of the entire system. Consequently, such tile assemblies are able\nto carry transverse mechanical loads. Archimedean and Laves tilings are\ninvestigated as templates for the material system architecture. It is\ndemonstrated under point loads that the architecture significantly affects the\nforce-deflection response. Stiffness, load carrying capacity and toughness\nvaried by a factor of at least three from the system with the poorest\nperformance to the system with the best performance. Across all architectures\nstiffness, strength and toughness are found to be strongly and linearly\ncorrelated. Architecture characterizing parameters and their relationship to\nthe mechanical behavior are investigated. It is shown that the measure of the\nsmallest tile area in an assembly provides the best predictor of mechanical\nbehavior. With small tiles present in the assembly the contact force network\nstructure is well developed and the internal load path is channeled through\nthese stiffest components of the assembly."
    },
    {
        "anchor": "Massive Dirac surface states in topological insulator/magnetic insulator\n  heterostructures: Topological insulators are new states of matter with a bulk gap and robust\ngapless surface states protected by time-reversal symmetry. When time-reversal\nsymmetry is broken, the surface states are gapped, which induces a topological\nresponse of the system to electromagnetic field--the topological\nmagnetoelectric effect. In this paper we study the behavior of topological\nsurface states in heterostructures formed by a topological insulator and a\nmagnetic insulator. Several magnetic insulators with compatible magnetic\nstructure and relatively good lattice matching with topological insulators\n${\\rm Bi_2Se_3}, {\\rm Bi_2Se_3}, {\\rm Sb_2Te_3}$ are identified, and the best\ncandidate material is found to be MnSe, an anti-ferromagnetic insulator. We\nperform first-principles calculation in ${\\rm Bi_2Se_3/MnSe}$ superlattices and\nobtain the surface state bandstructure. The magnetic exchange coupling with\nMnSe induces a gap of $\\sim$54 meV at the surface states. In addition we tune\nthe distance between Mn ions and TI surface to study the distance dependence of\nthe exchange coupling.",
        "positive": "Formation mechanism of helical Q structure in Gd-based skyrmion\n  materials: Using the ab initio local force method, we investigate the formation\nmechanism of the helical spin structure in GdRu$_2$Si$_2$ and Gd$_2$PdSi$_3$.\nWe calculate the paramagnetic spin susceptibility and find that the Fermi\nsurface nesting is not the origin of the incommensurate modulation, in contrast\nto the naive scenario based on the Ruderman-Kittel-Kasuya-Yosida mechanism. We\nthen decompose the exchange interactions between the Gd spins into each orbital\ncomponent, and show that spin-density-wave type interaction between the Gd-5$d$\norbitals is ferromagnetic, but the interaction between the Gd-4$f$ orbitals is\nantiferromagnetic. We conclude that the competition of these two interactions,\nnamely, the inter-orbital frustration, stabilizes the finite-Q structure."
    },
    {
        "anchor": "An ab-initio study of topological and transport properties of YAuPb: In the last few decades, the study of topological materials has been carried\nout on an extensive scale. Half-Heusler alloys are well known for their\ntopological behaviours. In this work, we present a detailed study of\ntopological properties of a ternary Half-Heusler alloy, YAuPb, using the\ntight-binding approach. We have calculated some important topological\nproperties which includes$-$ finding nodes and their chiralities, Berry\ncurvature ($\\boldsymbol\\Omega$) and the surface-states. Based on the study of\nthese properties, we categorise the material as non-trivial topological\nsemimetal. Besides the topological behaviours, we present a comparative study\nof temperature dependent transport properties corresponding to the chemical\npotential ($\\mu$) of the Fermi level and the node points. The results obtained\nfrom the calculations of electrical conductivity per unit relaxation time\n($\\boldsymbol\\sigma/\\tau$) and the electronic part of thermal conductivity per\nunit relaxation time ($\\boldsymbol\\kappa_0$) indicates the conducting nature of\nthe material to both the heat and electricity. Furthermore, the negative value\nof $S$ obtained, indicates the n-type behaviour of the compound. The calculated\nvalue of electronic specific heat (Pauli magnetic susceptibility) corresponding\nto Fermi level is $\\sim 0.03 \\hspace{1mm}(0.18) \\times 10^{-2}$ $\nJmol^{-1}K^{-1}$ ($\\sim 1.21 \\hspace{1mm}(1.14) \\times 10^{-10}$ $\nm^{3}mol^{-1}$) at 50 (300) K. This work suggests that YAuPb is a promising\ncandidate of non-trivial topological semimetals which can be employed in\ntransmission of heat and electricity, and as n-type material within the\ntemperature range of 50-300 K.",
        "positive": "Calculating the r^{-n} Interactions, 1<= n< 3, in a Periodic System with\n  a Neutralizing Background Charge Density: The $r^{-n}$ interaction energy, $1\\leq n< 3$, for a infinitely periodic\nsystem with explicit charges and a neutralizing, uniform background charge\ndensity is derived. An Ewald based expression for this energy has an extra term\nproportional to the square of the total explicit charges of the system. This\nexpression may be useful for simulations in which explicit charge neutrality\ndoes not hold or for which the total explicit charges is a fluctuating\nquantity."
    },
    {
        "anchor": "Finite Element Approximation of Finite Deformation Dislocation Mechanics: We develop and demonstrate the first general computational tool for finite\ndeformation static and dynamic dislocation mechanics. A finite element\nformulation of finite deformation (Mesoscale) Field Dislocation Mechanics\ntheory is presented. The model is a minimal enhancement of classical\ncrystal/$J_2$ plasticity that fundamentally accounts for polar/excess\ndislocations at the mesoscale. It has the ability to compute the static and\ndynamic finite deformation stress fields of arbitrary (evolving) dislocation\ndistributions in finite bodies of arbitrary shape and elastic anisotropy under\ngeneral boundary conditions. This capability is used to present a comparison of\nthe static stress fields, at finite and small deformations, for screw and edge\ndislocations, revealing heretofore unexpected differences. The computational\nframework is verified against the sharply contrasting predictions of\ngeometrically linear and nonlinear theories for the stress field of a spatially\nhomogeneous dislocation distribution in the body, as well as against other\nexact results of the theory. Verification tests of the time-dependent numerics\nare also presented. Size effects in crystal and isotropic versions of the\ntheory are shown to be a natural consequence of the model and are validated\nagainst available experimental data. With inertial effects incorporated, the\ndevelopment of an (asymmetric) propagating Mach cone is demonstrated in the\nfinite deformation theory when a dislocation moves at speeds greater than the\nlinear elastic shear wave speed of the material.",
        "positive": "Electron-phonon scattering dynamics in ferromagnets on ultrafast\n  timescales: Influence of the phonon temperature: The magnetization response of bulk ferromagnets after excitation by an\nultrashort optical pulse is calculated using a dynamical model of the\nElliott-Yafet type that includes the effects of the spin-orbit interaction in\nthe ab-initio ferromagnetic band structure, the electron-phonon interaction at\nthe level of Boltzmann scattering integrals, and dynamical changes in the\ntemperature of the phonon bath. Using realistic parameters for the ultrashort\noptical pulse, the computed maximum magnetization quenching achievable with\nelectron-phonon scattering in a fixed band structure is much smaller than the\nquenching observed in experiments. Heating of the phonon bath is found to not\nappreciably change the magnetization dynamics on ultrashort timescales."
    },
    {
        "anchor": "Stress evolution in plastically deformed austenitic and ferritic steels\n  determined using angle- and energy-dispersive diffraction: In the presented research, the intergranular elastic interaction and the\nsecond-order plastic incompatibility stress in textured ferritic and austenitic\nsteels were investigated by means of diffraction. The lattice strains were\nmeasured inside the samples by the multiple reflection method using high energy\nX-rays diffraction during uniaxial in situ tensile tests. Comparing experiment\nwith various models of intergranular interaction, it was found that the\nEshelby-Kr\\\"oner model correctly approximates the X-ray stress factors (XSFs)\nfor different reflections hkl and scattering vector orientations. The verified\nXSFs were used to investigate the evolution of the first and second-order\nstresses in both austenitic and ferritic steels. It was shown that considering\nonly the elastic anisotropy, the non-linearity of $\\sin^2{\\psi}$ plots cannot\nbe explained by crystallographic texture. Therefore, a more advanced method\nbased on elastic-plastic self-consistent modeling (EPSC) is required for the\nanalysis. Using such methodology the non-linearities of $\\cos^2{\\phi}$ plots\nwere explained, and the evolutions of the first and second-order stresses were\ndetermined. It was found that plastic deformation of about 1- 2% can completely\nexchange the state of second-order plastic incompatibility stresses.",
        "positive": "Spin-polarized surface states close to adatoms on Cu(111): We present a theoretical study of surface states close to 3d transition metal\nadatoms (Cr, Mn, Fe, Co, Ni and Cu) on a Cu(111) surface in terms of an\nembedding technique using the fully relativistic Korringa-Kohn-Rostoker method.\nFor each of the adatoms we found resonances in the s-like states to be\nattributed to a localization of the surface states in the presence of an\nimpurity. We studied the change of the s-like densities of states in the\nvicinity of the surface state band-edge due to scattering effects mediated via\nthe adatom's d-orbitals. The obtained results show that a magnetic impurity\ncauses spin-polarization of the surface states. In particular, the long-range\noscillations of the spin-polarized s-like density of states around an Fe adatom\nare demonstrated."
    },
    {
        "anchor": "Excitonically-Induced Mechanisms of Inelastic Processes in Rare-Gas\n  Solids: The models of permanent lattice defect formation in rare-gas solids are\ndiscussed with a focus on a point defect formation in solid Ar. The processes\nof large-scale atomic displacements induced by electronic excitations were\nstudied using the selective vacuum ultraviolet spectroscopy method. The\ncoexistence of intrinsic excitonic mechanism and extrinsic Rydberg state\ninduced excited-state mechanism of Frenkel defect formation was found.",
        "positive": "Theoretical Discovery/Prediction: Weyl Semimetal states in the TaAs\n  material (TaAs, NbAs, NbP, TaP) class: The recent discoveries of Dirac fermions in graphene and on the surface of\ntopological insulators have ignited worldwide interest in physics and materials\nscience. A Weyl semimetal is an unusual crystal where electrons also behave as\nmassless quasi-particles but interestingly they are not Dirac fermions. These\nmassless particles, Weyl fermions, were originally considered in massless\nquantum electrodynamics but have not been observed as a fundamental particle in\nnature. A Weyl semimetal provides a condensed matter realization of Weyl\nfermions, leading to unique transport properties with novel device\napplications. Here, we THEORETICALLY identify the first Weyl semimetal in a\nclass of stoichiometric materials (TaAs, NbAs, NbP, TaP), which break\ncrystalline inversion symmetry, including TaAs, TaP, NbAs and NbP. Our\nfirst-principles calculation-based predictions on TaAs reveal the\nspin-polarized Weyl cones and Fermi arc surface states in this compound. We\nalso observe pairs of Weyl points with the same chiral charge which project\nonto the same point in the surface Brillouin zone, giving rise to multiple\nFermi arcs connecting to a given Weyl point. Our results show that TaAs is the\nfirst topological semimetal identified which does not depend on fine-tuning of\nchemical composition or magnetic order, greatly facilitating an exploration of\nWeyl physics in real materials. (Note added: This theoretical prediction of\nNovember 2014 (see paper in Nature Communications) was the basis for the first\nexperimental discovery of Weyl Fermions and topological Fermi arcs in TaAs\nrecently published in Science (2015) at\nhttp://www.sciencemag.org/content/early/2015/07/15/science.aaa9297.full.pdf)"
    },
    {
        "anchor": "Recovering the flat-plane condition in electronic structure theory at\n  semi-local DFT cost: The flat plane condition is the union of two exact constraints in electronic\nstructure theory: i) energetic piecewise linearity with fractional electron\nremoval or addition and ii) invariant energetics with change in electron spin\nin a half filled orbital. Semi-local density functional theory (DFT) fails to\nrecover the flat plane, exhibiting convex fractional charge errors (FCE) and\nconcave fractional spin errors (FSE) that are related to delocalization and\nstatic correlation errors. We previously showed that DFT+U eliminates FCE but\nnow demonstrate that, like other widely employed corrections (i.e., Hartree\nFock exchange), it worsens FSE. To find an alternative strategy, we examine the\nshape of semi-local DFT deviations from the exact flat plane, and we find this\nshape to be remarkably consistent across ions and molecules. We introduce the\njmDFT approach, wherein corrections are constructed from few-parameter, low-\norder, functional forms that fit the shape of semi-local DFT errors. We select\none such physically intuitive form and incorporate it self-consistently to\ncorrect semi-local DFT. We demonstrate on model systems that this jmDFT\napproach represents the first easy-to-implement, no-overhead approach to\nrecovering the flat plane from semi-local DFT.",
        "positive": "Robust multicolor single photon emission from point defects in hexagonal\n  boron nitride: Hexagonal boron nitride (hBN) is an emerging two dimensional material for\nquantum photonics owing to its large bandgap and hyperbolic properties. Here we\nreport a broad range of multicolor room temperature single photon emissions\nacross the visible and the near infrared spectral ranges from point defects in\nhBN multilayers. We show that the emitters can be categorized into two general\ngroups, but most likely possess similar crystallographic structure. We further\nshow two approaches for engineering of the emitters using either electron beam\nirradiation or annealing, and characterize their photophysical properties. The\nemitters exhibit narrow line widths of sub 10 nm at room temperature, and a\nshort excited state lifetime with high brightness. Remarkably, the emitters are\nextremely robust and withstand aggressive annealing treatments in oxidizing and\nreducing environments. Our results constitute the first step towards\ndeterministic engineering of single emitters in 2D materials and hold great\npromise for the use of defects in boron nitride as sources for quantum\ninformation processing and nanophotonics."
    },
    {
        "anchor": "Chemical analysis of ligand-free silicon nanocrystal surfaces by surface\n  enhanced Raman spectroscopy: Surface enhanced Raman spectroscopy (SERS) was used to probe the surface\nchemistry of chlorine-terminated silicon nanocrystal (Si-NC) surfaces in an\nair-free environment. SERS effect was observed from the thin films of Ag$_x$O\nusing 514 nm laser wavelength. When a monolayer of Si-NCs were spin-coated on\nAg$_x$O SERS substrates, a very clear signal of surface states, including\nSi-Cl$_x$, and Si-H$_x$ were observed. Upon air-exposure, we observed the\ntemporal reduction of Si-Cl$_x$ peak intensity, and a development of\noxidation-related peak intensities, like Si-O$_x$ and Si-O-H$_x$. In addition,\nfirst, second and third order transverse optical (TO) modes of Si-NCs were also\nobserved at 519, 1000 and 1600 cm$^{-1}$, respectively. As a comparison, Raman\nanalysis of a thick film (> 200 nm) of Si-NCs deposited on ordinary glass\nsubstrates were performed. This analysis only demonstrated the first TO mode of\nSi-NCs, and the all the other features originated from SERS enhancement did not\nappear in the spectrum. These results conclude that, SERS is not only capable\nof single-molecule detection, but also a powerful technique for monitoring the\nsurface chemistry of nanoparticles.",
        "positive": "Double Kagome bands in a two-dimensional phosphorus carbide P2C3: The interesting properties of Kagome bands, consisting of Dirac bands and a\nflat band, have attracted extensive attention. However, the materials with only\none Kagome band around the Fermi level cannot possess physical properties of\nDirac fermions and strong correlated fermions simultaneously. Here, we propose\na new type of band structure --- double Kagome bands, which can realize\ncoexistence of the two kinds of fermions. Moreover, the new band structure is\nfound to exist in a new two-dimensional material, phosphorus carbide P2C3. The\ncarbide material shows good stability and unusual electronic properties. Strong\nmagnetism appears in the structure by hole doping of the flat band, which\nresults in spin splitting of the Dirac bands. The edge states induced by Dirac\nand flat bands coexist on the Fermi level, indicating outstanding transport\ncharacteristics. In addition, a possible route to experimentally grow P2C3 on\nsome suitable substrates such as the Ag (111) surface is also discussed."
    },
    {
        "anchor": "The absorption spectrum of hydrogenated silicon carbide nanocrystals\n  from ab initio calculations: The electronic structure and absorption spectrum of hydrogenated silicon\ncarbide nanocrystals (SiCNC) have been determined by first principles\ncalculations. We show that the reconstructed surface can significantly change\nnot just the onset of absorption, but the \\emph{shape} of the spectrum at\nhigher energies. We found that the absorption treshold of the reconstructed\nSiCNs cannot be accurately predicted from traditional density functional theory\ncalculations.",
        "positive": "Synthesis of boron carbide from its elements up to 13 GPa: The formation of boron carbide under high pressures and from elemental\nreactants has been studied and optimum parameters have been determined by\nvarying the (P, T, reactants) conditions. To this end, stoichiometric mixtures\nof commercial beta rhombohedral boron and amorphous glassy carbon have been\nsubjected to temperatures ranging from 1473 K to 2473 K at pressures of 2 GPa,\n5 GPa and 13 GPa. Similar syntheses have been repeated for mixtures of beta\nboron and graphite, and amorphous boron and amorphous carbon at 2 GPa and 5\nGPa. The carbon concentration of boron carbide is shown to be affected by\npressure at which it is synthesised from elements, and we propose pressure as a\nmeans to control the carbon content. The formation temperature is shown to be\naffected by the pressure and the choice of the reactants. The effect of\ntemperature cycling on the formation temperature has also been studied. The\nformation of alpha boron as an intermediate phase is seen at 5 GPa before the\nformation of boron carbide."
    },
    {
        "anchor": "Large Seebeck Effect by Charge-Mobility Engineering: The Seebeck effect describes the generation of an electric potential in a\nconducting solid exposed to a temperature gradient. Besides fundamental\nrelevance in solid state physics, it serves as a key quantity to determine the\nperformance of functional thermoelectric materials. In most cases, it is\ndominated by an energy-dependent electronic density of states at the Fermi\nlevel, in line with the prevalent efforts toward superior thermoelectrics\nthrough the engineering of electronic structure. Here, we demonstrate an\nalternative source for the Seebeck effect based on charge-carrier relaxation: A\ncharge mobility that changes rapidly with temperature can result in a sizeable\naddition to the Seebeck coefficient. This new Seebeck source is demonstrated\nexplicitly for Ni-doped CoSb3, where a dramatic mobility change occurs due to\nthe crossover between two different charge-relaxation regimes. Our findings\nunveil the origin of pronounced features in the Seebeck coefficient of many\nother elusive materials characterized by a significant mobility mismatch. As\nthe physical origin for the latter can vary greatly, our proposal provides a\nunifying framework for the understanding of a large panoply of thermoelectric\nphenomena. When utilized appropriately, this effect can also provide a novel\nroute to the design of improved thermoelectric materials for applications in\nsolid-state cooling or power generation.",
        "positive": "In-plane angular dependence of the spin-wave nonreciprocity of an\n  ultrathin film with Dzyaloshinskii-Moriya interaction: The nonreciprocal propagation of spin waves in an ultrathin Pt/Co/Ni film has\nbeen measured by Brillouin light scattering. The frequency nonreciprocity, due\nto the interfacial Dzyaloshinskii-Moriya interaction (DMI), has a sinusoidal\ndependence on the in-plane angle between the magnon wavevector and the applied\nmagnetic field. The results, which are in good agreement with analytical\npredictions reported earlier, yield a value of the DMI constant which is the\nsame as that obtained previously from a study of the magnon dispersion\nrelations. We have demonstrated that our magnon-dynamics based method can\nexperimentally ascertain the DMI constant of multilayer thin films."
    },
    {
        "anchor": "Atomistic deformation behavior of single and twin crystalline Cu\n  nanopillars with preexisting dislocations: Molecular dynamics simulations are performed to investigate the role of a\ncoherent {\\Sigma}3 (111) twin boundary on the plastic deformation behavior of\nCu nanopillars. Our work reveals that the mechanical response of pillars with\nand without the twin boundary is decisively driven by the characteristics of\ninitial dislocation sources. In the condition of comparably large pillar size\nand abundant initial mobile dislocations, overall yield and flow stresses are\ncontrolled by the longest, available mobile dislocation. An inverse correlation\nof the yield and flow stresses with the length of the longest dislocation is\nestablished, and its extrapolation agrees well with experimental yield stress\ndata. The experimentally reported subtle differences in yield and flow stresses\nbetween pillars with and without the twin boundary are thus likely related to\nthe maximum lengths of the mobile dislocations. In the condition of comparably\nsmall pillar size, for which a reduction of mobile dislocations during heat\ntreatment and mechanical loading occurs, the mechanical response of pillars\nwith and without the twin boundary can be clearly distinguished. Dislocation\nstarvation during deformation is more clearly present in pillars without the\ntwin boundary than in pillars with the twin boundary because the twin boundary\nacts as a pinning surface for the dislocation network.",
        "positive": "Influence of a knot on the strength of a polymer strand: Many experiments have been done to determine the relative strength of\ndifferent knots, and these show that the break in a knotted rope almost\ninvariably occurs at a point just outside the `entrance' to the knot. The\ninfluence of knots on the properties of polymers has become of great interest,\nin part because of their effect on mechanical properties. Knot theory applied\nto the topology of macromolecules indicates that the simple trefoil or\n`overhand' knot is likely to be present with high probability in any long\npolymer strand. Fragments of DNA have been observed to contain such knots in\nexperiments and computer simulations. Here we use {\\it ab initio} computational\nmethods to investigate the effect of a trefoil knot on the breaking strength of\na polymer strand. We find that the knot weakens the strand significantly, and\nthat, like a knotted rope, it breaks under tension at the entrance to the knot."
    },
    {
        "anchor": "Giant Chern number of a Weyl nodal surface without upper limit: Weyl nodes can be classified into zero-dimensional (0D) Weyl points (WPs), 1D\nWeyl nodal lines (WNL) and 2D Weyl nodal surfaces (WNS), which possess finite\nChern numbers. Up to date, the largest Chern number of WPs identified in Weyl\nsemimetals is 4, which is thought to be a maximal value for linearly crossing\npoints in solids. On the other hand, whether the Chern numbers of\nnonzero-dimensional linear crossing Weyl nodal objects have one upper limit is\nstill an open question. In this work, combining angle-resolved photoemission\nspectroscopy with density functional theory calculations, we show that the\nchiral crystal AlPt hosts a cube-shaped charged Weyl nodal surface which is\nformed by the linear crossings of two singly-degenerate bands. Different to\nconventional Weyl nodes, the cube-shaped nodal surface in AlPt is enforced by\nnonsymmorphic chiral symmetries and time reversal symmetry rather than\naccidental band crossings, and it possesses a giant Chern number |C| = 26.\nMoreover, our results and analysis prove that there is no upper limit for the\nChern numbers of such kind 2D Weyl nodal object.",
        "positive": "The potentially multiferroic Aurivillius phase Bi$_5$FeTi$_3$O$_{15}$:\n  cation site preference, electric polarization, and magnetic coupling from\n  first principles: We study the structural, ferroelectric, and magnetic properties of the\npotentially multiferroic Aurivillius phase material Bi$_5$FeTi$_3$O$_{15}$\nusing first principles electronic structure calculations. Calculations are\nperformed both with PBE and PBEsol exchange correlation functionals. We\nconclude that PBE systematically overestimates the lattice constants and the\nmagnitude of the ferroelectric distortion, whereas PBEsol leads to good\nagreement with available experimental data. We then assess a potential site\npreference of the Fe$^{3+}$ cation by comparing 10 different distributions of\nthe perovskite $B$-sites. We find a slight preference for the \"inner\" site,\nconsistent with recent experimental observations. We obtain a large value of\n$\\sim$55 $\\mu$C/cm$^2$ for the spontaneous electric polarization, which is\nrather independent of the specific Fe distribution. Finally, we calculate the\nstrength of the magnetic coupling constants and find strong antiferromagnetic\ncoupling between Fe$^{3+}$ cations in nearest neighbor positions, whereas the\ncoupling between further neighbors is rather weak. This poses the question\nwhether magnetic long range order can occur in this system in spite of the low\nconcentration of magnetic ions."
    },
    {
        "anchor": "Generalization of the Franck-Condon model for phonon excitations by\n  resonant inelastic X-ray scattering: Resonant inelastic X-ray scattering (RIXS) is increasingly used to quantify\nvibronic interactions in materials. In the case of periodic systems, this is\nmost often done through fitting experimental results to a parameterized, but\nexact analytical solution of a simple Holstein Hamiltonian that consists of a\nsingle electronic level coupled linearly to a single Einstein vibrational mode.\nWorking within this standard framework, we consider the impact of minor\ngeneralizations of this model, namely, introducing a second Einstein\noscillator, and allowing the curvature of the excited-state potential energy\nsurface to differ from that of the ground-state potential energy surface. We\nfind that dynamics occurring in the RIXS intermediate (excited) state\nconsiderably alter the quantitative interpretation of the spectral features\nobserved in the RIXS final state. This complicates the use of the single mode\nmodel when multiple phonon modes are active. Our generalized model may in\nprinciple by substituted in this case, though we find that accurate\nquantitative results rely on knowledge of the excited-state potential energy\nsurface, though this typically is not known.",
        "positive": "Spin-current injection and detection in strongly correlated organic\n  conductor: Spin-current injection into an organic semiconductor\n$\\rm{\\kappa\\text{-}(BEDT\\text{-}TTF)_2Cu[N(CN)_2]Br}$ film induced by the spin\npumping from an yttrium iron garnet (YIG) film. When magnetization dynamics in\nthe YIG film is excited by ferromagnetic or spin-wave resonance, a voltage\nsignal was found to appear in the\n$\\rm{\\kappa\\text{-}(BEDT\\text{-}TTF)_2Cu[N(CN)_2]Br}$ film.\nMagnetic-field-angle dependence measurements indicate that the voltage signal\nis governed by the inverse spin Hall effect in\n$\\rm{\\kappa\\text{-}(BEDT\\text{-}TTF)_2Cu[N(CN)_2]Br}$. We found that the\nvoltage signal in the $\\rm{\\kappa\\text{-}(BEDT\\text{-}TTF)_2Cu[N(CN)_2]Br}$/YIG\nsystem is critically suppressed around 80 K, around which magnetic and/or glass\ntransitions occur, implying that the efficiency of the spin-current injection\nis suppressed by fluctuations which critically enhanced near the transitions."
    },
    {
        "anchor": "Roundness of grains in cellular microstructures: Many physical systems are composed of polyhedral cells of varying sizes and\nshapes. These structures are simple in the sense that no more than three faces\nmeet at an edge and no more than four edges meet at a vertex. This means that\nindividual cells can usually be considered as simple, three-dimensional\npolyhedra. This paper is concerned with determining the distribution of\ncombinatorial types of such polyhedral cells. We introduce the terms\n\\emph{fundamental} and \\emph{vertex-truncated} types and apply these concepts\nto the grain growth microstructure as a testing ground. For these\nmicrostructures we demonstrate that most grains are of particular fundamental\ntypes, whereas the frequency of vertex-truncated types decreases exponentially\nwith the number of truncations. This can be explained by the evolutionary\nprocess through which grain growth structures are formed, and in which\nenergetically unfavorable surfaces are quickly eliminated. Furthermore, we\nobserve that these grain types are `round' in a combinatorial sense: there are\nno `short' separating cycles that partition the polyhedra into two parts of\nsimilar sizes. A particular microstructure derived from the Poisson--Voronoi\ninitial condition is identified as containing an unusually large proportion of\nround grains. This Round microstructure has an average of $14.036$ faces per\ngrain, and is conjectured to be more resistant to topological change than the\nsteady-state grain growth microstructure.",
        "positive": "Magnetic Chirality Induced from Ruderman-Kittel-Kasuya-Yosida\n  Interaction at an Interface of a Ferromagnet/Heavy Metal Heterostructure: We study a microscopic derivation and the properties of the\nDzyaloshinskii-Moriya interaction (DMI) between local magnetic moments in\nferromagnet/heavy metal heterostructures. First, we derive DMI by\nRuderman-Kittel-Kasuya-Yosida interaction through electrons in a heavy metal\nwith Rashba spin orbit interaction (SOI). Next, we study the dependences of the\nDMI on the Rashba SOI, lattice constant, and chemical potential. We find that\nthe DMI amplitude increases linearly when the Rashba SOI is small, has a\nmaximum when the Rashba SOI is comparable to the hopping integral, and\ndecreases when the Rashba SOI is large. The sign of the DMI not only changes\ndepending on the sign of the Rashba SOI but also the lattice constants and the\nchemical potential of the heavy metal. The implications of the obtained results\nfor experiments are discussed."
    },
    {
        "anchor": "An accurate measurement of electron beam induced displacement cross\n  sections for single-layer graphene: We present an accurate measurement and a quantitative analysis of\nelectron-beam induced displacements of carbon atoms in single-layer graphene.\nWe directly measure the atomic displacement (\"knock-on\") cross section by\ncounting the lost atoms as a function of the electron beam energy and applied\ndose. Further, we separate knock-on damage (originating from the collision of\nthe beam electrons with the nucleus of the target atom) from other radiation\ndamage mechanisms (e.g. ionization damage or chemical etching) by the\ncomparison of ordinary (12C) and heavy (13C) graphene. Our analysis shows that\na static lattice approximation is not sufficient to describe knock-on damage in\nthis material, while a very good agreement between calculated and experimental\ncross sections is obtained if lattice vibrations are taken into account.",
        "positive": "Modulational instability of magnetoelastic metamaterials: We study the modulational instability of recently designed magnetoelastic\nmetamaterials composed of elastic-mediated split-ring resonators (SRR). An\neffective circuit model is developed. Then four cases are studied: a dimer of\nSRR, one-dimension (1D) dimerized array, 1D uniform array and two-dimension\nlayered array. It is found that except for the dimer case, all the other\nmany-body cases can present modulational instability which may disturb the\nbistability (if any) under uniform assumption."
    },
    {
        "anchor": "Edge reconstruction induces magnetic and metallic behavior in zigzag\n  graphene nanoribbons: The edge reconstruction of zigzag graphene nanoribbons to a stable line of\nalternatively fused seven and five membered rings with hydrogen passivation has\nbeen studied within density functional theory with both localized and extended\nbasis approximations. Reconstruction of both edges results in a nonmagnetic\nmetallic ground state, whereas the one edge reconstruction stabilizes the\nsystem in a ferromagnetic metallic ground state. The reconstructed edge\nsuppresses the local spin density of atoms and contributes finite density of\nstates at Fermi energy. Our study paves a new way to fabricate the metallic\nelectrodes for semiconducting graphene devices with full control over the\nmagnetic behavior without any lattice mismatch between leads and the channel.",
        "positive": "Evidence against the polarization rotation model of piezoelectric\n  perovskites at the morphotropic phase boundary: The origin of the very large piezoelectric response observed in the vicinity\nof the morphotropic phase boundary (MPB) in perovskite lead zirconate titanate\nand related systems has been under intensive studies. Polarization rotation\nideas are frequently invoked to explain the piezoelectric properties. It was\nrecently reported that lead titanate undergoes a phase transformation sequence\n$P4mm\\to Pm\\to Cm\\to R\\bar{3}c$ at 10 K as a function of hydrostatic pressure\n[M. Ahart et al. Nature Letters. \\textbf{451}, 545 (2008)]. We demonstrate that\nthis interpretation is not correct by (i) simulating the reported diffraction\npatterns, and (ii) by density-functional theory computations which show that\nneither the $Pm$, $Cm$ nor $Pmm2$ phase is stable in the studied pressure\nrange, and further show that octahedral tilting is the key stabilization\nmechanism under high pressure. Notes on a more general ground are given to\ndemonstrate that a continuous phase transition between rhombohedral and\ntetragonal phases via intermediate monoclinic phase is not possible. Thus,\ntwo-phase co-existence in the vicinity of the phase transition region is\nprobable and has an important role for electromechanical properties."
    },
    {
        "anchor": "Dielectric properties of PLZT-x/65/35 (2 \\leqslant x \\leqslant 13) under\n  mechanical stress, electric field and temperature loading: We investigated the effect of uniaxial pressure (0-1000 bars) applied\nparallely to the ac electric field on dielectric properties of PLZT-x/65/35 (2\n\\leqslant x \\leqslant 13) ceramics. There was revealed a significant effect of\nthe external stress on these properties. The application of uniaxial pressure\nleads to the change of the peak intensity of the electric permittivity\n(\\varepsilon), of the frequency dispersion as well as of the dielectric\nhysteresis. The peak intensity $\\varepsilon$ becomes diffused/sharpened and\nshifts to a higher/lower temperatures with increasing the pressure. It was\nconcluded that the application of uniaxial pressure induces similar effects as\nincreasing the Ti ion concentration in PZT system. We interpreted our results\nbased on the domain switching processes under the action of combined\nelectromechanical loading.",
        "positive": "Spin polarization gate device based on the chirality-induced spin\n  selectivity and robust nonlocal spin polarization: Nonlocal spin polarization phenomena are thoroughly investigated in the\ndevices made of chiral metallic single crystals of CrNb$_3$S$_6$ and NbSi$_2$\nas well as of polycrystalline NbSi$_2$. We demonstrate that simultaneous\ninjection of charge currents in the opposite ends of the device with the\nnonlocal setup induces the switching behavior of spin polarization in a\ncontrollable manner. Such a nonlocal spin polarization appears regardless of\nthe difference in the materials and device dimensions, implying that the\ncurrent injection in the nonlocal configuration splits spin-dependent chemical\npotentials throughout the chiral crystal even though the current is injected\ninto only a part of the crystal. We show that the proposed model of the spin\ndependent chemical potentials explains the experimental data successfully. The\nnonlocal double-injection device may offer significant potential to control the\nspin polarization to large areas because of the nature of long-range nonlocal\nspin polarization in chiral materials."
    },
    {
        "anchor": "Properties of In-Plane Graphene/MoS2 Heterojunctions: The graphene/MoS2 heterojunction formed by joining the two components\nlaterally in a single plane promises to exhibit a low-resistance contact\naccording to the Schottky-Mott rule. Here we provide an atomic-scale\ndescription of the structural, electronic, and magnetic properties of this type\nof junction. We first identify the energetically favorable structures in which\nthe preference of forming C-S or C-Mo bonds at the boundary depends on the\nchemical conditions. We find that significant charge transfer between graphene\nand MoS2 is localized at the boundary. We show that the abundant 1D boundary\nstates substantially pin the Fermi level in the lateral contact between\ngraphene and MoS2, in close analogy to the effect of 2D interfacial states in\nthe contacts between 3D materials. Furthermore, we propose specific ways in\nwhich these effects can be exploited to achieve spin-polarized currents.",
        "positive": "Polytypism in Few-Layer Gallium Selenide: Gallium selenide (GaSe) is one of layered group-III metal monochalcogenides,\nwhich has an indirect bandgap in monolayer and direct bandgap in bulk unlike\nother conventional transition metal dichalcogenides (TMDs) such as MoX2 and WX2\n(X=S and Se). Four polytypes of bulk GaSe, designated as beta-, epsilon-,\ngamma-, and delta-GaSe, have been reported. Since different polytypes result in\ndifferent optical and electrical properties even for the same thickness,\nidentifying the polytype is essential in utilizing this material for various\noptoelectronic applications. We performed polarized Raman measurement on GaSe\nand found different ultra-low-frequency Raman spectra of inter-layer\nvibrational modes even for the same thickness due to different stacking\nsequences of the polytypes. By comparing the ultra-low-frequency Raman spectra\nwith theoretical calculations and high-resolution electron microscopy\nmeasurements, we established the correlation between the ultra-low-frequency\nRaman spectra and the stacking sequences for trilayer GaSe. We further found\nthat the AB-type stacking is more stable than the AA'-type stacking in GaSe."
    },
    {
        "anchor": "Dynamical Diffraction Theory for Wave Packet Propagation in Deformed\n  Crystals: We develop a theory for the trajectory of an x ray in the presence of a\ncrystal deformation. A set of equations of motion for an x-ray wave packet\nincluding the dynamical diffraction is derived, taking into account the Berry\nphase as a correction to geometrical optics. The trajectory of the wave packet\nhas a shift of the center position due to a crystal deformation. Remarkably, in\nthe vicinity of the Bragg condition, the shift is enhanced by a factor $\\omega\n/\\Delta \\omega$ ($\\omega$: frequency of an x ray, $\\Delta\\omega$: gap frequency\ninduced by the Bragg reflection). Comparison with the conventional dynamical\ndiffraction theory is also made.",
        "positive": "Exploring the potential of GeTe for the application in\n  Thermophotovoltaic (TPV) cell: Germanium telluride (GeTe) having a direct bandgap of 0.6 eV has mainly been\nin phase change memory and thermoelectric power generation. In this article, we\nstudy the electronic structure of the GeTe by first-principles calculations.\nThe theoretical direct bandgap of GeTe was found to be 0.69 eV which is very\nclose to the experimental value. Then, we demonstrate a single-junction GeTe\nthermophotovoltaic (TPV) cell based on device transport model with np\nstructure. The device was optimized for the higher performance of the TPV cell.\nThe GeTe TPV cell exhibited an efficiency of 7.9% with JSC=16.16 A/cm2,\nVOC=0.360 V and FF=75.51%, respectively. These results indicate that GeTe could\nbe a promising material for the fabrication of efficient TPV cell."
    },
    {
        "anchor": "The valence band energy spectrum of HgTe quantum wells with inverted\n  band structures: The energy spectrum of the valence band in HgTe/Cd$_x$Hg$_{1-x}$Te quantum\nwells with a width $(8-20)$~nm has been studied experimentally by\nmagnetotransport effects and theoretically in framework $4$-bands $kP$-method.\nComparison of the Hall density with the density found from period of the\nShubnikov-de Haas (SdH) oscillations clearly shows that the degeneracy of\nstates of the top of the valence band is equal to 2 at the hole density $p<\n5.5\\times 10^{11}$~cm$^{-2}$. Such degeneracy does not agree with the\ncalculations of the spectrum performed within the framework of the $4$-bands\n$kP$-method for symmetric quantum wells. These calculations show that the top\nof the valence band consists of four spin-degenerate extremes located at $k\\neq\n0$ (valleys) which gives the total degeneracy $K=8$. It is shown that taking\ninto account the \"mixing of states\" at the interfaces leads to the removal of\nthe spin degeneracy that reduces the degeneracy to $K=4$. Accounting for any\nadditional asymmetry, for example, due to the difference in the mixing\nparameters at the interfaces, the different broadening of the boundaries of the\nwell, etc, leads to reduction of the valleys degeneracy, making $K=2$. It is\nnoteworthy that for our case two-fold degeneracy occurs due to degeneracy of\ntwo single-spin valleys. The hole effective mass ($m_h$) determined from\nanalysis of the temperature dependence of the amplitude of the SdH oscillations\nshow that $m_h$ is equal to $(0.25\\pm0.02)\\,m_0$ and weakly increases with the\nhole density. Such a value of $m_h$ and its dependence on the hole density are\nin a good agreement with the calculated effective mass.",
        "positive": "Prominent room temperature valley polarization in WS2/graphene\n  heterostructures grown by chemical vapor deposition: We examine different cases of heterostructures consisting of WS2 monolayers\ngrown by chemical vapor deposition (CVD) as the optically active material. We\nshow that the degree of valley polarization of WS2 is considerably influenced\nby the material type used to form the heterostructure. Our results suggest the\ninteraction between WS2 and graphene (WS2/Gr) has a strong effect on the\ntemperature dependent depolarization (i.e. decrease of polarization with\nincreasing temperature), with polarization degrees reaching 24% at room\ntemperature under near-resonant excitation. This contrasts to hBN- encapsulated\nWS2, which exhibits a room temperature polarization degree of only 11%. The\nobserved low depolarization rate in WS2/Gr heterostructure is attributed to the\nnearly temperature independent scattering rate due to phonons and fast charge\nand energy transfer processes from WS2 to graphene. Significant variations in\nthe degree of polarization are also observed at 4K between the different\nheterostructure configurations. Intervalley hole scattering in the valence band\nproximity between the K and {\\Gamma} points of WS2 is sensitive to the\nimmediate environment, leading to the observed variations."
    },
    {
        "anchor": "On the effect of slip transfer at grain boundaries on the strength of\n  FCC polycrystals: The effect of slip transfer on the flow strength of various FCC polycrystals\nwas analyzed by means of computational homogenization of a representative\nvolume element of the microstructure. The crystal behavior was governed by a\nphysically-based crystal plasticity model in the framework of finite strains\nwhere slip transfer at grain boundaries was allowed between slip systems\nsuitably oriented according to geometrical criteria. Conversely, slip transfer\nwas blocked if the conditions for slip transfer were not fulfilled, leading to\nthe formation of dislocation pile-ups. All the model parameters for each\nmaterial were identified from either dislocation dynamics simulations or\nexperimental data from the literature. Slip transfer led to a reduction in the\nflow stress of the polycrystals (as compared with the simulations with opaque\ngrain boundaries) which was dependent on the fraction of translucent and\ntransparent grain boundaries in the microstructure. Moreover, dislocation\ndensities and Von Mises stresses were much higher around opaque grain\nboundaries, which become suitable places for damage nucleation. Finally,\npredictions of the Hall-Petch effect in Al, Ni, Cu and Ag polycrystals\nincluding slip transfer were in better agreement with the literature results,\nas compared with predictions assuming that all grain boundaries are opaque,\nparticularly for small grain sizes ($<$ 20 $\\mu$m).",
        "positive": "Structurally and Chemically Compatible BiInSe3 Substrate for Topological\n  Insulator Thin Films: Quality of epitaxial films strongly depends on their structural and chemical\nmatch with the substrates: the more closely they match, the better the film\nquality is. Topological insulators (TI) such as Bi2Se3 thin films are of no\nexception. However, there do not exist commercial substrates that match with TI\nfilms both structurally and chemically, at the level commonly available for\nother electronic materials. Here, we introduce BiInSe3 bulk crystal as the best\nsubstrate for Bi2Se3 thin films. These films exhibit superior surface\nmorphology, lower defect density and higher Hall mobility than those on other\nsubstrates, due to structural and chemical match provided by the BiInSe3\nsubstrate. BiInSe3 substrate could accelerate the advance of TI research and\napplications."
    },
    {
        "anchor": "Towards Resolving Landauer's Paradox Through Direct Observation of\n  Multiscale Ferroelastic-Ferroelectric Interplay: Electric-polarization reversibility in nano-ferroelectric structures renders\nthem as a convenient platform for exploring phase transitions and developing\nenergy-efficient switching devices. However, the fundamental question of how\nferroic domains switch, i.e. how the polarization changes from one state to\nanother, is yet to be answered fully. There are contradicting models and a wide\nbody of accumulated data which disagree as to whether the switching requires\ndomain nucleation. Moreover, ferroelectric domains switch under electric fields\nthat are supposedly too weak to form nucleation sites, indicating that the\nlevel of disorder seen in real systems plays an important role. This\nlongstanding so-called Landauer's paradox is the ferroelectric equivalent to\nthe absence of raindrop formation in a dust-free vacuum, leading to\nsupersaturated vapors that cannot exist otherwise, e.g. in spinodal\ndecompositions or inhomogeneous nucleation environments. Here we show that\npolarization switching in ferroelectric-ferroelastic systems comprises domain\ntypes that differ by symmetry, lengthscale and switching energy. These domains\nswitch simultaneously thanks to intermediate-range order of organized pinning\nsites, supporting the previously-unexplained coexistence of\nnucleation-and-growth and nucleation-frustrated mechanisms. Our treatment is\napplicable to other Kolmogorov-Avrami systems with multi-scale phase\ntransitions. Finally, we demonstrate augmented electromechanical coupling based\non the collective motion of pinning sites, which is promising for nano\nelectro-mechanical and low-power switching devices.",
        "positive": "Predicting the formation and stability of oxide perovskites by\n  extracting underlying mechanisms using machine learning: The optimization of properties of perovskite oxides has drawn interest on\naccount of their diverse areas of application. In this work, the hierarchical\nclustering technique is used to reduce the multi-collinearity among selected\nfeatures from literature that are reported to have an effect on perovskite\nformation and stability. Operating on the vast composition space of double\noxide perovskite compositions available in literature and online repositories,\nin this manuscript, an attempt has been made to extract the relationship\nbetween the composition and structure to predict their formability and\nstability. Machine learning (ML) classifiers are trained on these datasets to\npredict novel stable perovskite compositions. The study uses a vast feature\nspace to narrow down the most important factors affecting the formability and\nstability in perovskite compounds. It also identifies stable compositions that\nhave band gaps suitable for photovoltaic and photocatalytic applications. The\ndeveloped random forest (RF)-based models may be extended to include the\nimplications beyond photosensitive applications by focusing on the\nphysico-chemical mechanisms driving the phenomena behind each application."
    },
    {
        "anchor": "Optical and electronic properties in amorphous BaSnO3 thin films: Wide-bandgap perovskite stannates are of interest for the emergent all-oxide\ntransparent electronic devices due to their unparalleled room temperature\nelectron mobility. Considering the advantage of amorphous material in\nintegrating with non-semiconductor platforms, we herein reported the optical\nand electronic properties in the prototypical stannate, amorphous barium\nstannate (BaSnO3) thin films, which were deposited at room temperature and\nannealed at various temperatures. Despite remaining amorphous status, with\nincreasing the annealing temperature, the defect level within amorphous BaSnO3\nthin films could be suppressed.",
        "positive": "Magneto-optic dynamics in a ferromagnetic nematic liquid crystal: We investigate dynamic magneto-optic effects in a ferromagnetic nematic\nliquid crystal experimentally and theoretically. Experimentally we measure the\nmagnetization and the phase difference of the transmitted light when an\nexternal magnetic field is applied. As a model we study the coupled dynamics of\nthe magnetization, M, and the director field, n, associated with the liquid\ncrystalline orientational order. We demonstrate that the experimentally studied\nmacroscopic dynamic behavior reveals the importance of a dynamic cross-coupling\nbetween M and n. The experimental data are used to extract the value of the\ndissipative cross-coupling coefficient. We also make concrete predictions about\nhow reversible cross-coupling terms between the magnetization and the director\ncould be detected experimentally by measurements of the transmitted light\nintensity as well as by analyzing the azimuthal angle of the magnetization and\nthe director out of the plane spanned by the anchoring axis and the external\nmagnetic field. We derive the eigenmodes of the coupled system and study their\nrelaxation rates. We show that in the usual experimental set-up used for\nmeasuring the relaxation rates of the splay-bend or twist-bend eigenmodes of a\nnematic liquid crystal one expects for a ferromagnetic nematic liquid crystal a\nmixture of at least two eigenmodes."
    },
    {
        "anchor": "Spin dynamics from time-dependent density functional perturbation theory: We present a new method to model spin-wave excitations in magnetic solids,\nbased on the Liouville-Lanczos approach to time-dependent density functional\nperturbation theory. This method avoids computationally expensive sums over\nempty states and naturally deals with the coupling between spin and charge\nfluctuations, without ever explicitly computing charge-density\nsusceptibilities. Spin-wave excitations are obtained with one Lanczos chain per\nmagnon wave-number and polarization, avoiding the solution of the\nlinear-response problem for every individual value of frequency, as other\nstate-of-the-art approaches do. Our method is validated by computing magnon\ndispersions in bulk Fe and Ni, resulting in agreement with previous theoretical\nstudies in both cases, and with experiment in the case of Fe. The disagreement\nin the case of Ni is also comparable with that of previous computations.",
        "positive": "Orientational dependence of current through molecular films: We study the current through molecular films as a function of orientation of\nthe molecules in the film with respect to electrodes. It may change by more\nthan an order of magnitude, depending on the angle between the axis of the\nmolecules and the normal to the electrode. This is a consequence of a strong\ndirectional character of $p$-orbitals that determines the conductance through\nthe molecules. We demonstrate this result on an exactly solvable model, and\npresent the calculations for two different experimentally accessible molecular\nfilms sandwiched between gold electrodes."
    },
    {
        "anchor": "Real-time Measurement of Stress and Damage Evolution During Initial\n  Lithiation of Crystalline Silicon: Crystalline to amorphous phase transformation during initial lithiation in\n(100) silicon-wafers is studied in an electrochemical cell with lithium metal\nas the counter and reference electrode. It is demonstrated that severe stress\njumps across the phase boundary lead to fracture and damage, which is an\nessential consideration in designing silicon based anodes for lithium ion\nbatteries. During initial lithiation, a moving phase boundary advances into the\nwafer starting from the surface facing the lithium electrode, transforming\ncrystalline silicon into amorphous LixSi. The resulting biaxial compressive\nstress in the amorphous layer is measured in situ and it was observed to be ca.\n0.5 GPa. HRTEM images reveal that the crystalline-amorphous phase boundary is\nvery sharp, with a thickness of ~ 1 nm. Upon delithiation, the stress rapidly\nreverses, becomes tensile and the amorphous layer begins to deform plastically\nat around 0.5 GPa. With continued delithiation, the yield stress increases in\nmagnitude, culminating in sudden fracture of the amorphous layer into\nmicro-fragments and the cracks extend into the underlying crystalline silicon.",
        "positive": "Enhanced ferromagnetic moment in Co-doped BiFeO3 thin films studied by\n  soft X-ray circular dichroism: BiFeO$_3$ (BFO) shows both ferroelectricity and magnetic ordering at room\ntemperature but its ferromagnetic component, which is due to spin canting, is\nnegligible. Substitution of transition-metal atoms such as Co for Fe is known\nto enhance the ferromagnetic component in BFO. In order to reveal the origin of\nsuch magnetization enhancement, we performed soft x-ray absorption spectroscopy\n(XAS) and soft x-ray magnetic circular dichroism (XMCD) studies of\nBiFe$_{1-x}$Co$_x$O$_3$ ({\\it x} = 0 to 0.30) (BFCO) thin films grown on\nLaAlO$_3$(001) substrates. The XAS results indicated that the Fe and Co ions\nare in the Fe$^{3+}$ and Co$^{3+}$ states. The XMCD results showed that the Fe\nions show ferromagnetism while the Co ions are antiferromagnetic at room\ntemperature. The XAS and XMCD measurements also revealed that part of the\nFe$^{3+}$ ions are tetrahedrally co-ordinated by oxygen ions but that the XMCD\nsignals of the octahedrally coordinated Fe$^{3+}$ ions increase with Co\ncontent. The results suggest that an impurity phase such as the ferrimagnetic\n$\\gamma$-Fe$_2$O$_3$ which exists at low Co concentration decreases with\nincreasing Co concentration and that the ferromagnetic component of the\nFe$^{3+}$ ion in the octrahedral crystal fields increases with Co\nconcentration, probably reflecting the increased canting of the Fe$^{3+}$ ions."
    },
    {
        "anchor": "Comparing Methods of Characterizing Energetic Disorder in Organic Solar\n  Cells: Energetic disorder has been known for decades to limit the performance of\nstructurally disordered semiconductors such as amorphous silicon and organic\nsemiconductors. However, in the past years, high performance organic solar\ncells have emerged showing a continuously reduced amount of energetic disorder.\nWhile searching for future high efficiency material systems, it is therefore\nimportant to correctly characterize this energetic disorder. While there are\nseveral techniques in literature, the most common approaches to probe the\ndensity of defect states are using optical excitation as in external quantum\nefficiency measurements or sequential filling of the tail states by applying an\nexternal voltage as in admittance spectroscopy. A metanalysis of available\nliterature as well as our experiments using four characterization techniques on\ntwo material systems reveal that electrical, voltage-dependent measurements\nfrequently yield higher values of energetic disorder than optical measurements.\nWith drift-diffusion simulations, we demonstrate that the approaches probe\ndifferent energy ranges of the subband-gap density of states. We further\nexplore the limitations of the techniques and find that extraction of\ninformation from a capacitance-voltage curve can be inhibited by an internal\nseries resistance. Thereby, we explain the discrepancies between measurements\ntechniques with sensitivity to different energy ranges and electronic\nparameters.",
        "positive": "Vibrational Frequencies of Cerium Oxide-Bound CO: A Challenge for\n  Conventional DFT Methods: In ceria-based catalysis, the shape of the catalyst particle, which\ndetermines the exposed crystal facets, profoundly affects its reactivity. The\nvibrational frequency of adsorbed carbon monoxide (CO) can be used as a\nsensitive probe to identify the exposed surface facets, provided reference data\non well-defined single crystal surfaces together with a definitive theoretical\nassignment exist. We investigate the adsorption of CO on the CeO2(110 and (111)\nsurfaces and show that the commonly applied DFT(PBE)+U method does not provide\nreliable CO vibrational frequencies by comparing with state-of-the-art infrared\nspectroscopy experiments for monocrystalline CeO2 surfaces. Good agreement\nrequires the hybrid DFT approach with the HSE06 functional. The failure of\nconventional DFT is explained in terms of its inability to accurately describe\nthe facet- and configuration-specific donation and backdonation effects that\ncontrol the changes in the C-O bond length upon CO adsorption and the CO force\nconstant. Our findings thus provide a theoretical basis for the detailed\ninterpretation of experiments and open up the path to characterize more complex\nscenarios, including oxygen vacancies and metal adatoms."
    },
    {
        "anchor": "Dynamical lattice thermal conductivity, Shastry sum rule and second\n  sound in bulk semiconductor crystals: The paper discusses the fundamental behavior of the dynamical lattice thermal\nconductivity k(W) of bulk cubic semiconductor crystals. The calculation\napproach is based on solving Boltzmann-Peierls Phonon Transport Equation in the\nfrequency domain after excitation by a dynamical temperature gradient, within\nthe framework of the single relaxation time approximation and using modified\nDebye-Callaway model. Our model allows us to obtain a compact expression for\nk(W) that captures the leading behavior of the dynamical thermal conduction by\nphonons. This expression fulfills the causality requirement and leads to a\nconvolution type relationship between the heat flux density current and the\ntemperature gradient in the real space-time domain in agreement with\nGurtin-Pipkin theory. The dynamical behavior of k(W) is studied by changing\nambient temperature as well as different intrinsic and extrinsic parameters\nincluding the effect of embedding semiconductor nanoparticles as extrinsic\nphonon scattering centers. The paper investigates also the applicability of\nShastry Sum Rule and the possibility of existence and propagation of second\nsound in the frame work of Boltzmann theory.",
        "positive": "Multiscale modeling of thermomechanical behaviour of three-phase\n  nanocomposite: In this work, we developed an improved shear lag model to investigate the\nload transfer characteristics of three-phase nanocomposite which is reinforced\nwith microscale fibers augmented with carbon nanotubes on their circumferential\nsurfaces. The shear lag model accounts for (i) radial and axial deformations of\ndifferent transversely isotropic constituents, (ii) thermomechanical loads on\nthe representative volume element (RVE), and (iii) staggering effect of\nadjacent RVEs. The results from the current newly developed shear lag model are\nvalidated with the finite element simulations and found to be in good\nagreement. Our study reveals that the reduction in the maximum value of the\naxial stress in the fiber and the interfacial shear stress along its length\nbecome more pronounced in the presence of applied thermomechanical loads on the\nstaggered RVEs. The existence of shear tractions along the RVE length plays a\nsignificant role in the load transfer characteristics and cannot be ignored."
    },
    {
        "anchor": "The magnetoresistance tensor of La(0.8)Sr(0.2)MnO(3): We measure the temperature dependence of the anisotropic magnetoresistance\n(AMR) and the planar Hall effect (PHE) in c-axis oriented epitaxial thin films\nof La(0.8)Sr(0.2)MnO(3), for different current directions relative to the\ncrystal axes, and show that both AMR and PHE depend strongly on current\norientation. We determine a magnetoresistance tensor, extracted to 4th order,\nwhich reflects the crystal symmetry and provides a comprehensive description of\nthe data. We extend the applicability of the extracted tensor by determining\nthe bi-axial magnetocrystalline anisotropy in our samples.",
        "positive": "Electric and Magnetic response in dielectric dark states for low loss\n  subwavelength optical meta atoms: Created surfaces or meta surfaces, composed of appropriately shaped\nsub-wavelength structures, namely, meta-atoms, control light at wavelength\nscales. Historically, meta surfaces have used radiating metallic resonators as\nwavelength inclusions. However, while resonant optical meta surfaces made from\nmetal have been sub-wavelength in the propagation direction, they are too loss\nfor many applications."
    },
    {
        "anchor": "Modes of Kink Motion on Dislocations in Semiconductors: Analysis is given of the changes of dislocation motion modes with stress and\ntemperature variation. Different regimes of dislocation kink pair formation and\nspreading (motion in the random potential, in the field of random forces, the\nquasi-localization) are considered. Discrepancies are discussed between the\ntheory and experimental data on dislocation velocities.",
        "positive": "Formation of Organic Color Centers in Air-Suspended Carbon Nanotubes\n  Using Vapor-Phase Reaction: Organic color centers in single-walled carbon nanotubes have demonstrated\nexceptional ability to generate single photons at room temperature in the\ntelecom range. Combining the color centers with pristine air-suspended tubes\nwould be desirable for improved performance, but all current synthetic methods\noccur in solution which makes them incompatible. Here we demonstrate formation\nof color centers in air-suspended nanotubes using vapor-phase reaction.\nFunctionalization is directly verified on the same nanotubes by\nphotoluminescence spectroscopy, with unambiguous statistics from more than a\nfew thousand individual nanotubes. The color centers show a strong\ndiameter-dependent emission intensity, which can be explained with a\ntheoretical model for chemical reactivity taking into account strain along the\ntube curvature. We are also able to estimate the defect density by comparing\nthe experiments with simulations based on a one-dimensional diffusion equation,\nwhereas the analysis of diameter dependent peak energies gives insight to the\nnature of the dopant states. Time-resolved measurements show a longer lifetime\nfor color center emission compared to E$_{11}$ exciton states. Our results\nhighlight the influence of the tube structure on vapor-phase reactivity and\nemission properties, providing guidelines for development of high-performance\nnear-infrared quantum light sources."
    },
    {
        "anchor": "Investigation of Temperature Dependent Optical Modes in GexAs35-xSe65\n  Thin Films: Structure Specific Raman, FIR and Optical Absorption Spectroscopy: In this article, we present a comprehensive study of temperature and\ncomposition dependent Raman spectroscopy of GexAs35-xSe65 thin films to\nunderstand different structural units responsible for optical properties.\nStrikingly, our experimental results uncover the ratio of GeSe4/2 tetrahedral\nand AsSe3/2 pyramidal units in GexAs35-xSe65 thin films and their linear\nscaling relationship with temperature and x. An important notable outcome of\nour study is the formation of Se8 rings at lower temperatures. Our experimental\nresults further provide interesting optical features, thermally and\ncompositionally tunable optical absorption spectra. Detailed structure specific\nFIR data at room temperature also present direct information on the structural\nunits in consistent with Raman data. We foresee that our studies are useful in\ndetermining the lightinduced response of these films and also for their\npotential applications in optics and optoelectronics.",
        "positive": "Structural and transport properties of highly Ru-deficient SrRu0.7O3\n  thin films prepared by molecular beam epitaxy: comparison with stoichiometric\n  SrRuO3: We investigate structural and transport properties of highly Ru-deficient\nSrRu0.7O3 thin films prepared by molecular beam epitaxy on (001) SrTiO3\nsubstrates. To distinguish the influence of the two types of disorders in the\nfilms, Ru vacancies within lattices and disorders near the interface, SrRu0.7O3\nthin films with various thicknesses (t = 1-60 nm) were prepared. It was found\nthat the influence of the former dominates the electrical and magnetic\nproperties when t > 5-10 nm, while that of the latter does when t < 5-10 nm.\nStructural characterizations revealed that the crystallinity, in terms of the\nSr and O sublattices, of SrRu0.7O3 thin films, is as high as that of the\nultrahigh-quality SrRuO3 ones. The Curie temperature (TC) analysis elucidated\nthat SrRu0.7O3 (TC = 140 K) is a material distinct from SrRuO3 (TC = 150 K).\nDespite the large Ru deficiency (30%), the SrRu0.7O3 films showed metallic\nconduction when t > 5 nm. In high-field magnetoresistance measurements, the\nfascinating phenomenon of Weyl fermion transport was not observed for the\nSrRu0.7O3 thin films irrespective of thickness, which is in contrast to the\nstoichiometric SrRuO3 films. The (magneto)transport properties suggest that a\npicture of carrier scattering due to the Ru vacancies is appropriate for\nSrRu0.7O3, and also that proper stoichiometry control is a prerequisite to\nutilizing the full potential of SrRuO3 as a magnetic Weyl semimetal and\ntwo-dimensional spin-polarized system. Nevertheless, the large tolerance in Ru\ncomposition (30 %) to metallic conduction is advantageous for some practical\napplications where SrRu1-xO3 is exploited as an epitaxial conducting layer."
    },
    {
        "anchor": "Very large Dzyaloshinskii-Moriya interaction in two-dimensional Janus\n  manganese dichalcogenides and its application to realize skyrmion states: The Dzyaloshinskii-Moriya interaction (DMI), which only exists in\nnoncentrosymmetric systems, is responsible for the formation of exotic chiral\nmagnetic states. The absence of DMI in most two-dimensional (2D) magnetic\nmaterials is due to their intrinsic inversion symmetry. Here, using\nfirst-principles calculations, we demonstrate that significant DMI can be\nobtained in a series of Janus monolayers of manganese dichalcogenides MnXY in\nwhich the difference between X and Y on the opposites sides of Mn breaks the\ninversion symmetry. In particular, the DMI amplitudes of MnSeTe and MnSTe are\ncomparable to those of state-of-the-art ferromagnet/heavy metal (FM/HM)\nheterostructures. In addition, by performing Monte Carlo simulations, we find\nthat at low temperatures the ground states of the MnSeTe and MnSTe monolayers\ncan transform from ferromagnetic states with worm-like magnetic domains into\nthe skyrmion states by applying external magnetic field. At increasing\ntemperature, the skyrmion states starts fluctuating above 50 K before an\nevolution to a completely disordered structure at higher temperature. The\npresent results pave the way for new device concepts utilizing chiral magnetic\nstructures in specially designed 2D ferromagnetic materials.",
        "positive": "Phono-magnetic analogs to opto-magnetic effects: The magneto-optical and opto-magnetic effects describe the interaction of\nlight with a magnetic medium. The most prominent examples are the Faraday and\nCotton-Mouton effects that modify the transmission of light through a medium,\nand the inverse Faraday and inverse Cotton-Mouton effects that produce\neffective magnetic fields for the spin in the material. Here, we introduce the\nphenomenology of the analogous magneto-phononic and phono-magnetic effects, in\nwhich vibrational quanta take the place of the light quanta. We show, using a\ncombination of first-principles calculations and phenomenological modeling,\nthat the effective magnetic fields exerted by the phonon analogs of the inverse\nFaraday and inverse Cotton-Mouton effects on the spins of antiferromagnetic\nnickel oxide yield magnitudes comparable to and potentially larger than those\nof the opto-magnetic originals."
    },
    {
        "anchor": "Center-of-Mass Properties of the Exciton in Quantum Wells: We present high-quality numerical calculations of the exciton center-of-mass\ndispersion for GaAs/AlGaAs quantum wells of widths in the range 2-20 nm. The\nk.p-coupling of the heavy- and light-hole bands is fully taken into account. An\noptimized center-of-mass transformation enhances numerical convergence. We\nderive an easy-to-use semi-analytical expression for the exciton groundstate\nmass from an ansatz for the exciton wavefunction at finite momentum. It is\nchecked against the numerical results and found to give very good results. We\nalso show multiband calculations of the exciton groundstate dispersion using a\nfinite-differences scheme in real space, which can be applied to rather general\nheterostructures.",
        "positive": "Phase Stability and Thermoelectric Properties of the Mineral FeS2: An Ab\n  Initio Study: First principles calculations were carried out to study the phase stability\nand thermoelectric properties of the naturally occurring marcasite phase of\nFeS$_2$ at ambient condition as well as under pressure. Two distinct density\nfunctional approaches has been used to investigate the above mentioned\nproperties. The plane wave pseudopotential approach was used to study the phase\nstability and structural, elastic, and vibrational properties. The full\npotential linear augment plane wave method has been used to study the\nelectronic structure and thermoelectric properties. From the total energy\ncalculations, it is clearly seen that marcasite FeS$_2$ is stable at ambient\nconditions, and it undergoes a first order phase transition to pyrite FeS$_2$\nat around 3.7 GPa with a volume collapse of about 3$\\%$. The calculated ground\nstate properties such as lattice parameters, bond lengths and bulk modulus of\nmarcasite FeS$_2$ agree quite well with the experiment. Apart from the above\nstudies, phonon dispersion curves unambiguously indicate that marcasite phase\nis stable under ambient conditions. Further, we do not observe any phonon\nsoftening across the marcasite to pyrite transition and the possible reason\ndriving the transition is also analyzed in the present study, which has not\nbeen attempted earlier. In addition, we have also calculated the electronic\nstructure and thermoelectric properties of the both marcasite and pyrite\nFeS$_2$. We find a high thermopower for both the phases, especially with p-type\ndoping, which enables us to predict that FeS$_2$ might find promising\napplications as good thermoelectric materials."
    },
    {
        "anchor": "Mechanical relaxation and fracture of phase field crystals: A computational method is developed for the study of mechanical response and\nfracture behavior of phase field crystals (PFC), to overcome a limitation of\nthe PFC dynamics which lacks an effective mechanism for describing fast\nmechanical relaxation of the material system. The method is based on a simple\ninterpolation scheme for PFC (IPFC) making use of a condition of the\ndisplacement field to satisfy local elastic equilibration, while preserving key\ncharacteristics of the original PFC model. We conduct a systematic study on the\nmechanical properties of a sample nanoribbon system with honeycomb lattice\nsymmetry subjected to uniaxial tension, for numerical validation of the IPFC\nscheme and the comparison with the original PFC and modified PFC methods.\nResults of mechanical response, in both elasticity and fracture regimes, show\nthe advantage and efficiency of the IPFC method across different system sizes\nand applied strain rates, due to its effective process of mechanical\nequilibration. A brittle fracture behavior is obtained in IPFC calculations,\nwhere effects of system temperature and chirality on the fracture strength and\nYoung's modulus are also identified, with results agreeing with those found in\nprevious atomistic simulations of graphene. The IPFC scheme developed here is\ngeneric and applicable to the mechanical studies using different types of PFC\nfree energy functionals designed for various material systems.",
        "positive": "Mechanical response of all-MoS2 single-layer hetrostructures: A ReaxFF\n  investigation: Molybdenum disulfide (MoS2) is a highly attractive 2D material due to its\ninteresting electronic properties. Recent experimental advances confirm the\npossibility of further tuning the electronic properties of MoS2 through the\nfabrication of single-layer heterostructures consisting of semiconducting (2H)\nand metallic (1T) MoS2 phases. Nonetheless, despite significant technological\nand scientific interest, there is currently limited information concerning the\nmechanical properties of these heterostructure systems. This investigation aims\nto extend our understanding of the mechanical properties of all-MoS2\nsingle-layer structures at room temperature. This goal was achieved by\nperforming extensive classical molecular dynamics simulations using a recently\ndeveloped RexFF forcefield. We first studied the direction dependent mechanical\nproperties of defect-free 2H and 1T phases. Our modelling results for pristine\n2H MoS2 were found to be in good agreement with the experimental tests and\nfirst-principles theoretical predictions. We also discuss the mechanical\nresponse of 2H/1T single layer heterostructures. Our reactive molecular\ndynamics results suggest all-MoS2 heterostructures as suitable candidates to\nprovide a strong and flexible material with tuneable electronic properties."
    },
    {
        "anchor": "The chemical state of complex uranium oxides: We report here the first direct observation of U(V) in uranium binary oxides\nand analyze the gradual conversion of the U oxidation state in the mixed\nuranium systems. Our finding clarifies previous contradicting results and\nprovides important input for the geological disposal of spent fuel, recycling\napplications and chemistry of uranium species.",
        "positive": "Charge polarization effects on the optical response of blue-emitting\n  superlattices: In the new approach to study the optical response of periodic structures,\nsuccessfully applied to study the optical properties of blue-emitting InGaN/GaN\nsuperlattices, the spontaneous charge polarization was neglected. To search the\neffect of this quantum confined Stark phenomenon we study the optical response,\nassuming parabolic band edge modulations in the conduction and valence bands.\nWe discuss the consequences on the eigenfunction symmetries and the ensuing\noptical transition selection rules. Using the new approach in the WKB\napproximation of the finite periodic systems theory, we determine the energy\neigenvalues, their corresponding eigenfunctions and the subband structures in\nthe conduction and valence bands. We calculate the photoluminescence as a\nfunction of the charge localization strength, and compare with the experimental\nresult. We show that for subbands close to the barrier edge the optical\nresponse and the surface states are sensitive to charge polarization strength."
    },
    {
        "anchor": "Novel Ground-State Crystals with Controlled Vacancy Concentrations: From\n  Kagom\u00e9 to Honeycomb to Stripes: We introduce a one-parameter family, $0 \\leq H \\leq 1$, of pair potential\nfunctions with a single relative energy minimum that stabilize a range of\nvacancy-riddled crystals as ground states. The \"quintic potential\" is a\nshort-ranged, nonnegative pair potential with a single local minimum of height\n$H$ at unit distance and vanishes cubically at a distance of $\\rt$. We have\ndeveloped this potential to produce ground states with the symmetry of the\ntriangular lattice while favoring the presence of vacancies. After an\nexhaustive search using various optimization and simulation methods, we believe\nthat we have determined the ground states for all pressures, densities, and $0\n\\leq H \\leq 1$. For specific areas below $3\\rt/2$, the ground states of the\n\"quintic potential\" include high-density and low-density triangular lattices,\nkagom\\'{e} and honeycomb crystals, and stripes. We find that these ground\nstates are mechanically stable but are difficult to self-assemble in computer\nsimulations without defects. For specific areas above $3\\rt/2$, these systems\nhave a ground-state phase diagram that corresponds to hard disks with radius\n$\\rt$. For the special case of H=0, a broad range of ground states is\navailable. Analysis of this case suggests that among many ground states, a\nhigh-density triangular lattice, low-density triangular lattice, and striped\nphases have the highest entropy for certain densities. The simplicity of this\npotential makes it an attractive candidate for experimental realization with\napplication to the development of novel colloidal crystals or photonic\nmaterials.",
        "positive": "ADAQ: Automatic workflows for magneto-optical properties of point\n  defects in semiconductors: Automatic Defect Analysis and Qualification (ADAQ) is a collection of\nautomatic workflows developed for high-throughput simulations of\nmagneto-optical properties of point defect in semiconductors. These workflows\nhandle the vast number of defects by automating the processes to relax the unit\ncell of the host material, construct supercells, create point defect clusters,\nand execute calculations in both the electronic ground and excited states. The\nmain outputs are the magneto-optical properties which include zero-phonon\nlines, zero-field splitting, and hyperfine coupling parameters. In addition,\nthe formation energies are calculated. We demonstrate the capability of ADAQ by\nperforming a complete characterization of the silicon vacancy in silicon\ncarbide in the polytype 4H (4H-SiC)."
    },
    {
        "anchor": "Pressure sensing using vertically aligned carbon nanotubes on a flexible\n  substrate: Sensing technologies have been under research and development for their\nvaried applications from microelectronics to space exploration. With the end of\nMoores law in sight, there is growing demand for shrinking materials and\nimproving sensitivity and range of sensing of sensors. Carbon nanotubes (CNTs)\noffer an excellent combination of small size (in the order of nanometers in two\ndimensions and micrometers in the third dimension), varied current conductivity\n(from insulating to metallic), flexibility, mechanical strength and feasibility\nof mass production. Here we used CNTs to fabricate pressure sensors to sense\nstatic loads of pressure and studied the characteristics of different methods\nof building the sensors. We offer an adhesive-absorption technique of\nfabrication of pressure sensors that tackles the issue of endurance of the\nsensors to repeated operation. We demonstrate a significant change in\nresistance of a vertically aligned forest of nanotubes upon application of\nstatic loads. This study will enable building of better pressure sensors for\nseveral applications.",
        "positive": "Design of bi-tortuous, anisotropic graphite anodes for fast\n  ion-transport in Li-ion batteries: Thick Li-ion battery electrodes with high ion transport rates could enable\nbatteries that cost less and that have higher gravimetric and volumetric energy\ndensity, because they require fewer inactive cell-components. Finding ways to\nincrease ion transport rates in thick electrodes would be especially valuable\nfor electrodes made with graphite platelets, which have been shown to have\ntortuosities in the thru-plane direction about 3 times higher than in the\nin-plane direction. Here, we predict that bi-tortuous electrode structures\n(containing electrolyte-filled macro-pores embedded in micro-porous graphite)\ncan enhance ion transport and can achieve double the discharge capacity\ncompared to an unstructured electrode at the same average porosity. We\nintroduce a new two-dimensional version of porous-electrode theory with\nanisotropic ion transport to investigate these effects and to interpret the\nmechanisms by which performance enhancements arise. From this analysis we\ndetermine criteria for the design of bi-tortuous graphite anodes, including the\nparticular volume fraction of macro-pores that maximizes discharge capacity\n(approximately 20 vol.%) and a threshold spacing interval (half the electrode's\nthickness) below which only marginal enhancement in discharge capacity is\nobtained. We also report the sensitivity of performance with respect to cycling\nrate, electrode thickness, and average porosity/electroactive-material loading."
    },
    {
        "anchor": "Novel Laves phase superconductor NbBe2: A theoretical investigation: A new Laves phase superconductor NbBe2, prototype with MgCu2, having maximum\nTc ~2.6 K has been reported very recently. Based on first-principle\ncalculations, we systematically study the structural, elastic, mechanical,\nelectronic, thermal and superconducting properties of the newly reported\nsuperconducting intermetallic compound NbBe2. Finally, we investigate the\nelectron-phonon coupling constant, phonon dispersion curve and density of\nstates which indicates that the compound under study is a weakly coupled BCS\nsuperconductor.",
        "positive": "Influence of fracture criteria on dynamic fracture propagation in a\n  discrete chain: The extent to which time-dependent fracture criteria affect the dynamic\nbehavior of fracture in a discrete structure is discussed in this work. The\nsimplest case of a semi-infinite isotropic chain of oscillators has been\nstudied. Two history-dependent criteria are compared to the classical one of\nthreshold elongation for linear bonds. The results show that steady-state\nregimes can be reached in the low subsonic crack speed range where it is\nimpossible according to the classical criterion. Repercussions in terms of load\nand crack opening versus velocity are explained in detail. A strong qualitative\ninfluence of history-dependent criteria is observed at low subsonic crack\nvelocities, especially in relation to achievable steady-state propagation\nregimes."
    },
    {
        "anchor": "Exponential suppression of thermal conductance using coherent transport\n  and heterostructures: We consider coherent thermal conductance through multilayer photonic crystal\nheterostructures, consisting of a series of cascaded non-identical photonic\ncrystals. We show that thermal conductance can be suppressed exponentially with\nthe number of cascaded crystals, due to the mismatch between photonic bands of\nall crystals in the heterostructure.",
        "positive": "Phenomenological theory of magnetic anisotropy in thin films and\n  multilayers: Within a phenomenological approach the density of induced uniaxial anisotropy\nin nanostructures K(r) is treated as a physical field additional to the\nmagnetization M(r). The equilibrium distributions of K(r) are formed under the\ninfluence of the surfaces and internal interactions. The functions K(r) and\nM(r) are calculated for a magnetic layer between two nonmagnetic spacers. It is\nshown that the transition from the phase with magnetization in plane to the\nperpendicular phase occurs continuously via an intermediate phase which is\ninhomogeneous across the layer-thickness. The theory explains experimentally\nobserved thickness dependences of the effective anisotropy and gives a method\nto obtain values of the characteristic parameters for the theory from\nexperimental data. It is shown that the separation of the induced anisotropy\ninto volume and surface contribution is valid only for thick films."
    },
    {
        "anchor": "Raman spectra of GexAsySe100-x-y glasses: Raman spectra of GexAsySe100-x-y (0 < x < 30; 10 < y < 40) glasses have been\nstudied at room temperature. Three sets of samples were investigated; it was\nrevealed that they are qualitatively differing by shape of their spectra. The\nstructure model was proposed for glasses of each set. The selection of the\nglasses on the sets with the same structure type can be made using the formal\nparameter - the mean coordination number <m> (the mean number of covalent bonds\nper atom): i) 2.1 < <m> < 2.51 (polymeric structure); ii) 2.51 < <m> < 2.78\n(molecular-cluster structure); iii) 2.78 < <m> < 3 (network structure).",
        "positive": "Direct measurement of electron-phonon coupling with time-resolved ARPES: Time and angular resolved photoelectron spectroscopy is a powerful technique\nto measure electron dynamics in solids. Recent advances in this technique have\nfacilitated band and energy resolved observations of the effect that excited\nphonons, have on the electronic structure. Here, we show with the help of\n\\textit{ab initio} simulations that the Fourier analysis of time-resolved\nmeasurements of solids with excited phonon modes leads, in fact, to an\nobservation of the band- and mode-resolved electron-phonon coupling directly\nfrom the experimental data and without need for theoretical computations."
    },
    {
        "anchor": "Lorenz Number and Electronic Thermoelectric Figure of Merit:\n  Thermodynamics and Direct DFT Calculations: The Lorenz number (L) contained in the Wiedemann-Franz law represents the\nratio of two kinetic parameters of electronic charge carriers: the electronic\ncontribution to the thermal conductivity (K_el) and the electrical conductivity\n(sigma), , and can be expressed as LT=K_el/sigma where T is temperature. We\ndemonstrate that the Lorenz number simply equals to the ratio of two\nthermodynamic quantities: the electronic heat capacity (c_el) and the\nelectrochemical capacitance (c_N) through LT=c_el/c_N , a purely thermodynamic\nquantity, and thus it can be calculated solely based on the electron density of\nstates of a material. It is shown that our thermodynamic formulation for the\nLorenz number leads to: i) the well-known Sommerfeld value L=pi^2/3(k_B/e)^2 at\nthe low temperature limit, ii) the Drude value L=3/2(k_B/e)^2 at the high\ntemperature limit with the free electron gas model, and iii) possible higher\nvalues than the Sommerfeld limit for semiconductors. It is also demonstrated\nthat the purely electronic contribution to the thermoelectric figure-of-merit\ncan be directly computed using high-throughput DFT calculations without\nresorting to the computationally more expensive Boltzmann transport theory to\nthe electronic thermal conductivity and electrical conductivity.",
        "positive": "Shallow impurity band in ZrNiSn: ZrNiSn and related half Heusler compounds are candidate materials for\nefficient thermoelectric energy conversion with a reported thermoelectric\nfigure-of-merit of n-type ZrNiSn exceeding unity. Progress on p-type materials\nhas been more limited, which has been attributed to the presence of an impurity\nband, possibly related to the presence of Ni interstitials in nominally vacant\n4d position. The specific energetic position of this band, however, has not\nbeen resolved. Here, we report results of a concerted theory-experiment\ninvestigation for a nominally undoped ZrNiSn, based on measurements of\nelectrical resistivity, Hall coefficient, Seebeck coefficient and Nernst\ncoefficient, measured in a temperature range from 80 to 420 K. The results are\nanalyzed with a semi-analytical model combining a density functional theory\n(DFT) description for ideal ZrNiSn, with a simple analytical correction for the\nimpurity band. The model provides a good quantitative agreement with\nexperiment, describing all salient features in the full temperature span for\nthe Hall, conductivity, and Seebeck measurements, while also reproducing key\ntrends in the Nernst results. This comparison pinpoints the impurity band edge\nto 40 meV below the conduction band edge, which agrees well with a separate DFT\nstudy of a supercell containing Ni interstitials. Moreover, we corroborate our\nresult with a separate study of ZrNiSn0.9Pb0.1 sample showing similar agreement\nwith an impurity band edge shifted to 32 meV below the conduction band."
    },
    {
        "anchor": "Magnetic properties of hexagonal YMnO$_3$, LuMnO$_3$ and ScMnO$_3$\n  Magnetic susceptibility, specific heat and dielectric constant of hexagonal\n  YMnO_3, LuMnO_3 and ScMnO_3: We report the magnetic susceptibility, specific heat and dielectric constant\non high purity polycrystalline samples of three hexagonal manganites: YMnO_3,\nLuMnO_3 and ScMnO_3. These materials can exhibit a ferroelectric transition at\nvery high temperatures (T_{FE} > 700K). At lower temperatures there is magnetic\nordering of the frustrated Mn^{3+} spins (S=2) on a triangular Mn lattice\n(YMnO_3:T_N=71K; LuMnO$_3:T_N=90K and ScMnO_3:T_N=130K). The transition is\ncharacterized by a sharp kink in the magnetic susceptibility at T_N below which\nit continues to increase due to the frustration on the triangular lattice. The\nspecific heat shows one clear continuous phase transition at T_N, which is\nindependent of external magnetic field up to 9T with an entropy content as\nexpected for Mn^{3+} ions. The temperature dependent dielectric constant\ndisplays a distinct anomaly at T_N.",
        "positive": "Interplays between charge and electric field in perovskite solar cells:\n  charge transport, recombination and hysteresis: Interplays between charge and electric field, which play a critical role in\ndetermining the charge transport, recombination, storage and hysteresis in the\nperovskite solar cell, have been systematically investigated by both electrical\ntransient experiments and theoretical calculations. It is found that the light\nillumination can increase the carrier concentration in the perovskite absorber,\nthus enhancing charge recombination and causing the co-existence of high\nelectric field and free carriers. Meanwhile, the cell shows a similar charge\nstorage and junction mechanism to that of the multicrystalline silicon solar\ncell, where the junction electric field determines the charge collection and\ndistribution. Furthermore, it is demonstrated that the static charge of both\nthe doping and defect coming from ion (vacancy) migration can significantly\ninfluence the electric field inside the cell, thus affecting the charge\ncollection and recombination, which could be the origins for the\nwidely-concerned hysteresis behaviors."
    },
    {
        "anchor": "Giant Magnetocaloric Effect in Re-entrant Ferromagnet PrMn1.4Fe0.6Ge2: Three first order magnetic phase transitions (FOMT) have been detected at\nTCPr, TNinter and TCinter over the temperature range from 5 K to 340 K at\nfields up to 9 T in PrMn1.4Fe0.6Ge2, and the magnetocaloric effect (MCE) around\nthese transitions evaluated. The MCE of two FOMT from planar antiferromagnetism\n(AFl) to c-axis ferromagnetism (Fmc) around 168 K, and from the Fmc state to\nthe c-axis AFmc state around 157 K have acceptable values compared with those\nof existing MCE systems. A giant magnetocaloric effect (GMCE) has been observed\naround 25.5 K associated with the field-induced FOMT from the AFmc to the\nFmc+F(Pr) state with an additional Pr magnetic contribution. The MCE value 29.1\nJ/kg K with field change 7 T is comparable to and even larger than reported\nvalues for the best-performed MCE materials. In particular, the giant MCE value\nof 12.3 J/kg K obtained for the relatively small field change from 0 to 1 T is\nvery beneficial for applications, and this, together with the small magnetic\nand thermal hysteresis, suggests that PrMn1.4Fe0.6Ge2 may be a promising\ncandidate for magnetic refrigeration applications in the hydrogen liquefication\ntemperature range.",
        "positive": "On the magnetization process of ferromagnetic materials: The present article concludes that a ferromagnetic sample could be considered\nlike a paramagnetic system where the role of magnetic moments plays magnetic\ndomains. Based on this conclusion and taking into account presence of an\nanisotropic field the formula which describes magnetization dependence on the\nexternal magnetic field is derived. Expressions for a remanent magnetization\nand a coercive force are presented. The new parameter to characterize a\nmagnetic stiffness of a material is introduced. A physical expression for a\ndynamic magnetic susceptibility as a function of material's characteristics,\nexternal magnetic field, and a temperature is given."
    },
    {
        "anchor": "Ferroelectricity induced by interatomic magnetic exchange interaction: Multiferroics, where two or more ferroic order parameters coexist, is one of\nthe hottest fields in condensed matter physics and materials science[1-9].\nHowever, the coexistence of magnetism and conventional ferroelectricity is\nphysically unfavoured[10]. Recently several remedies have been proposed, e.g.,\nimproper ferroelectricity induced by specific magnetic[6] or charge orders[2].\nGuiding by these theories, currently most research is focused on frustrated\nmagnets, which usually have complicated magnetic structure and low magnetic\nordering temperature, consequently far from the practical application. Simple\ncollinear magnets, which can have high magnetic transition temperature, have\nnever been considered seriously as the candidates for multiferroics. Here, we\nargue that actually simple interatomic magnetic exchange interaction already\ncontains a driving force for ferroelectricity, thus providing a new microscopic\nmechanism for the coexistence and strong coupling between ferroelectricity and\nmagnetism. We demonstrate this mechanism by showing that even the simplest\nantiferromagnetic (AFM) insulator MnO, can display a magnetically induced\nferroelectricity under a biaxial strain.",
        "positive": "Design of Mott and topological phases on buckled 3d-oxide honeycomb\n  lattices: Perovskite bilayers with (111)-orientation combine a honeycomb lattice as a\nkey feature with the strongly correlated, multiorbital nature of electrons in\ntransition metal oxides. In a systematic DFT+$U$ study of (111)-oriented\n(La$X$O$_3$)$_2$/(LaAlO$_3$)$_4$ superlattices, we establish trends in the\nevolution of ground states versus band filling in (111)-oriented\n(La$X$O$_3$)$_2$/(LaAlO$_3$)$_4$ superlattices, with $X$ spanning the entire\n$3d$ transition metal series. The competition between local quasi-cubic and\nglobal triangular symmetry triggers unanticipated broken symmetry phases, with\nmechanisms ranging from Jahn-Teller distortions, to charge-, spin-, and\norbital-ordering. LaMnO$_3$, where spin-orbit coupling opens a sizable gap in\nthe Dirac-point Fermi surface, emerges as a topological Chern insulator."
    },
    {
        "anchor": "The behavior of f-levels in HCP and BCC rare-earth elements in the\n  ground state and in XPS and BIS spectroscopy from density-functional theory: The electronic structures of rare-earth elements in the HCP structure, and\nEuropium in the BCC structure, are calculated by use of density-functional\ntheory, DFT. Simulation of X-ray photoemission spectroscopy (XPS) and\nbremsstrahlung isochromatic spectroscopy (BIS) are made within DFT by imposing\nthat f-electrons are excited by a large photon energy, either by removing from\nthe occupied states in XPS, or by adding to the unoccupied f-states in BIS. The\nresults show sizable differences in the apparent position of the f-states\ncompared to the f-band energy of the ground states. This result is\nfundamentally different from calculations assuming strong on-site correlation\nsince all calculations are based on DFT. Spin-orbit coupling and multiplet\nsplittings are not included. The present simulation accounts for almost half of\nthe difference between the f-level positions in the DFT ground states and the\nobserved f-level positions. The electronic specific heat at low T is compatible\nwith the DFT ground state, where f-electrons often reside at the Fermi level.",
        "positive": "(LaTiO$_3$)$_n$/(LaVO$_3$)$_n$ as a model system for unconventional\n  charge transfer and polar metallicity: At interfaces between oxide materials, lattice and electronic reconstructions\nalways play important roles in exotic phenomena. In this study, the density\nfunctional theory and maximally localized Wannier functions are employed to\ninvestigate the (LaTiO$_3$)$_n$/(LaVO$_3$)$_n$ magnetic superlattices. The\nelectron transfer from Ti$^{3+}$ to V$^{3+}$ is predicted, which violates the\nintuitive band alignment based on the electronic structures of LaTiO$_3$ and\nLaVO$_3$. Such unconventional charge transfer quenches the magnetism of\nLaTiO$_3$ layer mostly and leads to metal-insulator transition in the $n=1$\nsuperlattice when the stacking orientation is altered. In addition, the\ncompatibility among the polar structure, ferrimagnetism, and metallicity is\npredicted in the $n=2$ superlattice."
    },
    {
        "anchor": "Collective octahedral tilting in ultrathin Ruddlesden-Popper perovskite\n  under terahertz light: Perovskites have been applied in a wide range of fields such as solar cells\nand non-volatile memories due to their multiferroic nature and excellent\nphoto-electric conversion capabilities. Recently, two-dimensional (2D)\nperovskites with a few atomic layers have been successfully synthesized,\nattracting significant attention for potential applications. In this work, we\nperform first-principles calculations to investigate an ultrathin prototypical\nRuddlesden-Popper phase, $\\mathrm{Bi}_2\\mathrm{FeO}_4$, with its thickness down\nto one unit cell. We show that this compound could exist in two (meta-)stable\noctahedral tilting phases, belonging to $P2_1/c$ and $C2/m$ space groups,\nrespectively. Using the optomechanical theory, we suggest that reversible and\nnon-volatile phase switching can be triggered using non-destructive terahertz\nlight. In addition, the two phases show distinct optical reflectance spectrum\nin the visible light range, which can be used as an optical probe for phase\ntransformation. This enables both \"write\" and \"read\" in an all-optical route.",
        "positive": "Low frequency Raman spectroscopy of few-atomic-layer thick hBN crystals: Hexagonal boron nitride (hBN) has recently gained a strong interest as a\nstrategic component in engineering van der Waals heterostructures built with\ntwo dimensional crystals such as graphene. This work reports micro-Raman\nmeasurements on hBN flakes made of a few atomic layers, prepared by mechanical\nexfoliation. The temperature dependence of the Raman scattering in hBN is\ninvestigated first such as to define appropriate measurements conditions\nsuitable for thin layers avoiding undesirable heating induced effects. We\nfurther focus on the low frequency Raman mode corresponding to the rigid\nshearing oscillation between adjacent layers, found to be equal to 52.5 cm-1 in\nbulk hBN. For hBN sheets with thicknesses below typically 4 nm, the frequency\nof this mode presents discrete values, which are found to decrease down to\n46.0(5) cm-1 for a three-layer hBN, in good agreement with the linear-chain\nmodel. This makes Raman spectroscopy a relevant tool to quantitatively\ndetermine the number of layers in ultra thin hBN sheets, below 8L."
    },
    {
        "anchor": "Interaction of Acoustic and Optical Phonons in Soft Bonded Cu-Se\n  Framework of Large Unit Cell Minerals with Anionic Disorders: Large unit cell copper-chalcogenide based minerals with high crystalline\nanharmonicity have a potential for thermoelectric applications owing to their\ninherent poor lattice thermal conductivity. Here, the softening of\ncopper-selenium bonding and hence crystal framework plays an important role in\nsuperionic conduction and thermal conductivity. We have studied Cu26Nb2Sn6Se32,\nCu26Nb2Sn6Se31.5 and Cu26Nb2Sn6Se30Te2 minerals with a strategically tailored\nanionic disorders. These compounds have p-type degenerate behavior with carrier\nconcentration ranging between 1020 cm-3 at 300 K, high power factor and low\nlattice thermal conductivity at 640 K. The existence of two low frequency Raman\nactive optical modes associated with soft Cu and Se atoms, three localized\nEinstein modes in specific heat, suggest high scattering between acoustic and\noptical branches with very short phonon lifetime less than 1 ps. The excess\nvibrational density of states at low energies with compressed and flat optical\nbranches strongly hinders the heat transport in these crystalline mineral.\nComparatively, Cu26Nb2Sn6Se30Te2 is a promising thermoelectric material because\nof high crystalline anharmonicity and softening of Cu-Se framework due to\nheavier tellurium atom.",
        "positive": "Diameter-Selective Dispersion of Carbon Nanotubes via Polymers: A\n  Competition between Adsorption and Bundling: The mechanism of the selective dispersion of single-walled carbon nanotubes\n(CNTs) by polyfluorene polymers is studied in this paper. Using extensive\nmolecular dynamics simulations, it is demonstrated that diameter selectivity is\nthe result of a competition between bundling of CNTs and adsorption of polymers\non CNT surfaces. The preference for certain diameters corresponds to local\nminima of the binding energy difference between these two processes. Such\nminima in the diameter dependence occur due to abrupt changes in the CNT's\ncoverage with polymers and their calculated positions are in quantitative\nagreement with preferred diameters, reported experimentally. The presented\napproach defines a theoretical framework for the further understanding and\nimprovement of dispersion/extraction processes."
    },
    {
        "anchor": "Optimal switching of a nanomagnet assisted by microwaves: We develop an efficient and general method for optimizing the microwave field\nthat achieves magnetization switching with a smaller static field. This method\nis based on optimal control and renders an exact solution for the 3D microwave\nfield that triggers the switching of a nanomagnet with a given anisotropy and\nin an oblique static field. Applying this technique to the particular case of\nuniaxial anisotropy, we show that the optimal microwave field, that achieves\nswitching with minimal absorbed energy, is modulated both in frequency and in\nmagnitude. Its role is to drive the magnetization from the metastable\nequilibrium position towards the saddle point and then damping induces the\nrelaxation to the stable equilibrium position. For the pumping to be efficient,\nthe microwave field frequency must match at the early stage of the switching\nprocess the proper precession frequency of the magnetization, which depends on\nthe magnitude and direction of the static field. We investigate the effect of\nthe static field (in amplitude and direction) and of damping on the\ncharacteristics of the microwave field. We have computed the switching curves\nin the presence of the optimal microwave field. The results are in qualitative\nagreement with micro-SQUID experiments on isolated nanoclusters. The strong\ndependence of the microwave field and that of the switching curve on the\ndamping parameter may be useful in probing damping in various nanoclusters.",
        "positive": "Topological effects of three-dimensional porous graphene on Dirac\n  quasiparticles: This paper reports on the topological effects of three-dimensional (3D)\nporous graphene with tunable pore sizes and a preserved 2D graphene system of\nDirac quasiparticles on its electrical properties. This 3D architecture is\ncharacterized by the intrinsic curvature of smoothly interconcnected graphene\nsheets without edges, the structures and properties of which can be controlled\nwith its pore sizes. The impact of pore size on the electrical transport\nproperties was investigated through magnetoresistance measurements. We observed\nthat 3D graphene with small pores exhibits transitioning to weak localization\nwith decreasing temperature. The comparison with the theory based on the\nquantum correction clarified that an increase in the intrinsic curvature\nsignificantly induces the intervalley scattering event, which breaks the\nchirality. This increase in the intervalley scattering rate originates from the\nunique topological effects of 3D graphene, i.e., the topological defects\nrequired to form the high curvature and the resulting chirality mixing. We also\ndiscuss the scattering processes due to microscopic chemical bonding states as\nfound by high spatial-resolved X-ray photoemission spectral imaging, to support\nthe validity of our finding."
    },
    {
        "anchor": "Strong Plasmonic Enhancement of Photovoltage in Graphene: Amongst the wide spectrum of potential applications of graphene, ranging from\ntransistors and chemical-sensors to nanoelectromechanical devices and\ncomposites, the field of photonics and optoelectronics is believed to be one of\nthe most promising. Indeed, graphene's suitability for high-speed\nphotodetection was demonstrated in an optical communication link operating at\n10 Gbit/s\\cite. However, the low responsivity of graphene-based photodetectors\ncompared to traditional III-V based ones is a potential drawback. Here we show\nthat, by combining graphene with plasmonic nanostructures, the efficiency of\ngraphene-based photodectors can be increased by up to 20 times, due to field\nconcentration in the area of a p-n junction. Additionally, wavelength and\npolarization selectivity can be achieved employing nanostructures of different\ngeometries.",
        "positive": "First-Principles Exploration of Defect-Pairs in GaN: Using first-principles calculations, we explored all the 21 defect-pairs in\nGaN and considered 6 configurations with different defect-defect distances for\neach defect-pair. 15 defect-pairs with short defect-defect distances are found\nto be stable during structural relaxation, so they can exist in the GaN lattice\nonce formed during the irradiation of high-energy particles. 9 defect-pairs\nhave formation energies lower than 10 eV in the neutral state. The vacancy-pair\nVN-VN is found to have very low formation energies, as low as 0 eV in p-type\nand Ga-rich GaN, and act as efficient donors producing two deep donor levels,\nwhich can limit the p-type doping and minority carrier lifetime in GaN. VN-VN\nhas been overlooked in the previous study of defects in GaN. Most of these\ndefect-pairs act as donors and produce a large number of defect levels in the\nband gap. Their formation energies and concentrations are sensitive to the\nchemical potentials of Ga and N, so their influences on the electrical and\noptical properties of Ga-rich and N-rich GaN after irradiation should differ\nsignificantly. These results about the defect-pairs provide fundamental data\nfor understanding the radiation damage mechanism in GaN and simulating the\ndefect formation and diffusion behavior under irradiation."
    },
    {
        "anchor": "Physics-informed machine learning in asymptotic homogenization of\n  elliptic equations: We apply physics-informed neural networks (PINNs) to first-order two-scale\nperiodic asymptotic homogenization of the property tensor in a generic elliptic\nequation. The problem of lack of differentiability of property tensors at the\nsharp phase interfaces is circumvented by making use of diffuse interface\nformulation. Periodic boundary conditions are incorporated strictly, through\nthe introduction of an input-transfer layer (Fourier feature mapping), in which\nthe sine and cosine of the inner product of position vectors and reciprocal\nlattice vectors are considered. This, together with the absence of Dirichlet\nboundary conditions, results in a lossless boundary condition application. The\nonly loss terms are then due to the differential equation itself, which removes\nthe necessity of scaling the loss entries. In demonstrating the formulation's\nversatility based on the reciprocal lattice vectors, crystalline arrangements\ndefined with Bravais lattices are used. We also show that considering integer\nmultiples of the reciprocal basis in the Fourier mapping leads to improved\nconvergence of high-frequency functions. We consider applications in one, two,\nand three dimensions. Periodic composites, composed of embeddings of\nmonodisperse inclusions in the form of disks/spheres in the\ntwo-/three-dimensional matrix, are considered. For demonstration purposes,\nstochastic monodisperse disk arrangements are also considered.",
        "positive": "Observation of Topologically Protected States at Crystalline Phase\n  Boundaries in Single-layer WSe2: Transition metal dichalcogenide (TMD) materials are unique in the wide\nvariety of structural and electronic phases they exhibit in the two-dimensional\n(2D) single-layer limit. Here we show how such polymorphic flexibility can be\nused to achieve topological states at highly ordered phase boundaries in a new\nquantum spin Hall insulator (QSHI), 1T'-WSe2. We observe helical states at the\ncrystallographically-aligned interface between quantum a spin Hall insulating\ndomain of 1T'-WSe2 and a semiconducting domain of 1H-WSe2 in contiguous single\nlayers grown using molecular beam epitaxy (MBE). The QSHI nature of\nsingle-layer 1T'-WSe2 was verified using ARPES to determine band inversion\naround a 120 meV energy gap, as well as STM spectroscopy to directly image\nhelical edge-state formation. Using this new edge-state geometry we are able to\ndirectly confirm the predicted penetration depth of a helical interface state\ninto the 2D bulk of a QSHI for a well-specified crystallographic direction. The\nclean, well-ordered topological/trivial interfaces observed here create new\nopportunities for testing predictions of the microscopic behavior of\ntopologically protected boundary states without the complication of structural\ndisorder."
    },
    {
        "anchor": "Heterodiffusion coefficients in \u03b1-iron: The diffusion of tungsten in {\\alpha}-iron is important for the application\nof ferritic-iron alloys to thermal power plants. These data, over a wide\ntemperature range across the Curie temperature, have been recently reported. We\nshow that these diffusion coefficients can be satisfactory reproduced in terms\nof the bulk elastic and expansivity data by means of a thermodynamical model\nthat interconnects point defects parameters with bulk qualities.",
        "positive": "NSGAN: A Non-Dominant Sorting Optimisation-Based Generative Adversarial\n  Design Framework for Alloy Discovery: The design and discovery of new materials is fundamental to advancing\nscientific and technological innovation. The recent emergence of the materials\ngenome concept holds great promise in revolutionising materials science by\nenabling the systematic utilisation of data for efficient prediction and\noptimisation of superior materials. However, the materials genome approach can\nbe stymied by the vast complexity of design spaces, which often demand\nsubstantial computational resources and sophisticated data processing\ncapabilities. To address these challenges, this work introduces a novel\ngenerative design framework called the non-dominant sorting optimisation-based\ngenerative adversarial networks (NSGAN). Capitalising on the synergies of\ngenetic algorithms (GA) and generative adversarial networks (GANs), NSGAN\nprovides a robust and efficient approach for tackling high-dimensional\nmulti-objective optimisation design problems. To validate the efficacy of the\nproposed framework, we applied the model to a comprehensive dataset of\naluminium alloys. Additionally, an online tool was created as a supplementary\nresource, offering a brief introduction to this innovative method for the wider\nscientific community. This study explores the potential of a predictive and\ndata-driven approach in material design, indicating a promising pathway for\nwidespread applications in the field of materials science."
    },
    {
        "anchor": "Lindeman's criterion: diamond graphitization temperature and its\n  dependence on external pressure: A simple model for the \"diamond graphitization\" type of phase transition is\nproposed, leading to a good agreement with the experimental data. The phase\ntransition temperature dependence on the external pressure is found. A new\nphenomenon in diamond is predicted, which is a decrease of the temperature of\ngraphitization with increase of external pressure.",
        "positive": "Synthesis and study of alpha-Fe1.4Ga0.6O3: An advanced Ferromagnetic\n  Semiconductor: We report the synthesis of alpha-Fe1.4Ga0.6O3 compound and present its\nstructural phase stability and interesting magnetic, dielectric and\nphoto-absorption properties. In our work Ga doped alpha-Fe2O3 samples are well\nstabilized in alpha phase (rhombohedral crystal structure with space group\nR3C). Properties of the present composition of Ga doped alpha-Fe2O3 system are\nremarkably advanced in comparison with recently most studied FeGaO3\ncomposition. At room temperature the samples are typical soft ferromagnet, as\nwell as direct band gap semiconductor. Dielectric study showed low dielectric\nloss in the samples with large enhancement of ac conductivity at higher\nfrequencies. Optical absorption in the visible range has been enhanced by 4 to\n5%. This composition has exhibited large scope of tailoring room temperature\nferromagnetic moment and optical band gap by varying grain size and non-ambient\n(vacuum) heat treatment of the as prepared samples by mechanical alloying."
    },
    {
        "anchor": "Theory of hot-carrier generation in bimetallic plasmonic catalysts: Bimetallic nanoreactors in which a plasmonic metal is used to funnel solar\nenergy towards a catalytic metal have recently been studied experimentally, but\na detailed theoretical understanding of these systems is lacking. Here, we\npresent theoretical results of hot-carrier generation rates of different Au-Pd\nnanoarchitectures. In particular, we study spherical core-shell nanoparticles\nwith a Au core and a Pd shell as well as antenna-reactor systems consisting of\na large Au nanoparticle with acts as antenna and a smaller Pd satellite\nnanoparticle separated by a gap. In addition, we investigate an antenna-reactor\nsystem in which the satellite is a core-shell nanoparticle. Hot-carrier\ngeneration rates are obtained from an atomistic quantum-mechanical modelling\ntechnique which combines a solution of Maxwell's equation with a tight-binding\ndescription of the nanoparticle electronic structure. We find that\nantenna-reactor systems exhibit significantly higher hot-carrier generation\nrates in the catalytic material than the core-shell system as a result of\nstrong electric field enhancements associated with the gap between the antenna\nand the satellite. For these systems, we also study the dependence of\nhot-carrier generation rate on the size of the gap, the radius of the antenna\nnanoparticle and the direction of light polarization. Our insights pave the way\ntowards a mechanistic understanding of hot-carrier generation in heterogeneous\nnanostructures for photocatalysis and other energy conversion applications.",
        "positive": "Long-distance propagation of high-velocity antiferromagnetic spin waves: We report on coherent propagation of antiferromagnetic (AFM) spin waves over\na long distance ($\\sim$10 $\\mu$m) at room temperature in a canted AFM\n$\\alpha$-Fe$_2$O$_3$ with the Dzyaloshinskii-Moriya interaction (DMI).\nUnprecedented high group velocities (up to 22.5 km/s) are characterized by\nmicrowave transmission using all-electrical spin wave spectroscopy. We derive\nanalytically AFM spin-wave dispersion in the presence of the DMI which accounts\nfor our experimental results. The AFM spin waves excited by nanometric coplanar\nwaveguides with large wavevectors enter the exchange regime and follow a\nquasi-linear dispersion relation. Fitting of experimental data with our\ntheoretical model yields an AFM exchange stiffness length of 1.7 angstrom. Our\nresults provide key insights on AFM spin dynamics and demonstrate high-speed\nfunctionality for AFM magnonics."
    },
    {
        "anchor": "Biaxial strain tuned electronic structures and power factor in Janus\n  Transition Metal Dichalchogenide monolayers: Tuning physical properties of transition metal dichalcogenide (TMD)\nmonolayers by strain engineering have most widely studied, and recently Janus\nTMD monolayer MoSSe has been synthesized. In this work, we systematically study\nbiaxial strain dependence of electronic structures and transport properties of\nJanus TMD MXY (M = Mo or W, X/Y = S, Se, or Te) monolayer by using generalized\ngradient approximation (GGA) plus spin-orbit coupling (SOC). It is found that\nSOC has a noteworthy detrimental influence on power factor in p-type MoSSe,\nWSSe, n-type WSTe, p-type MoSeTe and WSeTe, and has a negligible influence on\none in n-type MoSSe, MoSTe, p-type WSTe and n-type MoSeTe. These can be\nunderstood by considering SOC effects on their valence and conduction bands.\nFor all six monolayers, the energy band gap firstly increases, and then\ndecreases, when strain changes from compressive one to tensile one. It is found\nthat strain can tune strength of bands convergence of both valence and\nconduction bands by changing the numbers and relative position of valence band\nextrema (VBE) or conduction band extrema (CBE), which can produce very\nimportant effects on their electronic transport properties. By applying\nappropriate compressive or tensile strain, both n- or p-type Seebeck\ncoefficient can be enhanced by strain-induced band convergence, and then the\npower factor can be improved. Our works further enrich studies on strain\ndependence of electronic structures and transport properties of new-style TMD\nmonolayers, and motivate farther experimental works.",
        "positive": "A Multiscale Approach for Modeling Crystalline Solids: In this paper we present a modeling approach to bridge the atomistic with\nmacroscopic scales in crystalline materials. The methodology combines\nidentification and modeling of the controlling unit processes at microscopic\nlevel with the direct atomistic determination of fundamental material\nproperties. These properties are computed using a many body Force Field derived\nfrom ab initio quantum-mechanical calculations. This approach is exercised to\ndescribe the mechanical response of high-purity Tantalum single crystals,\nincluding the effect of temperature and strain-rate on the hardening rate. The\nresulting atomistically informed model is found to capture salient features of\nthe behavior of these crystals such as: the dependence of the initial yield\npoint on temperature and strain rate; the presence of a marked stage I of easy\nglide, specially at low temperatures and high strain rates; the sharp onset of\nstage II hardening and its tendency to shift towards lower strains, and\neventually disappear, as the temperature increases or the strain rate\ndecreases; the parabolic stage II hardening at low strain rates or high\ntemperatures; the stage II softening at high strain rates or low temperatures;\nthe trend towards saturation at high strains; the temperature and strain-rate\ndependence of the saturation stress; and the orientation dependence of the\nhardening rate."
    },
    {
        "anchor": "Electron spin echo relaxation and envelope modulation of phosphorus\n  shallow donors in silicon: Spins of single donor atoms are attractive candidates for large scale quantum\ninformation processing in silicon, since quantum computation can be realized\nthrough the manipulation of electron and/or nuclear spins. We here report on\ntwo-pulse electron spin echo experiments on phosphorus shallow donors in\nnatural and 28Si-enriched silicon epilayers doped with 10^16 cm-3 P donors. The\nexperiments address the spin-spin relaxation times and mechanisms and provide,\nthrough the electron spin echo envelope modulation (ESEEM) effect, information\non the donor electron wave function. Experiments performed as a function of the\npulse turning angle allowed us to measure the exponential relaxation and\nspectral diffusion times depurated by instantaneous diffusion. According to\nthese results, isotopically purified samples are necessary to reduce the\nspectral diffusion contribution and the P shallow donors concentration plays a\nfundamental role in determining the intrinsic phase memory time. ESEEM peaks\nhave been assigned to hyperfine-coupled silicon-29 nuclei at specific\ncrystallographic positions on the basis of a spectral fit procedure including\ninstrumental distortions.",
        "positive": "Pettifor Maps of Complex Ternary Two-dimensional Transition Metal\n  Sulphides: Alloying is an established strategy to tune the properties of bulk compounds\nfor desired applications. With the advent of nanotechnology, the same strategy\ncan be applied to 2D materials for technological applications, like\nsingle-layer transistors and solid lubricants. Here we present a systematic\nanalysis of the phase behaviour of substitutional 2D alloys in the Transition\nMetal Disulphides (TMD) family. The phase behaviour is quantified in terms of a\nmetastability metric and benchmarked against many-body expansion of the energy\nlandscape. We show how the metastability metric can be directly used as\nstarting point for setting up rational search strategies in phase space, thus\nallowing for targeted further computational prediction and analysis of\nproperties. The results presented here also constitute a useful guideline for\nsynthesis of TMDs binary alloys via a range of synthesis techniques."
    },
    {
        "anchor": "Exploration of the High Entropy Alloy Space as a Constraint Satisfaction\n  Problem: High Entropy Alloys (HEAs), Multi-principal Component Alloys (MCA), or\nCompositionally Complex Alloys (CCAs) are alloys that contain multiple\nprincipal alloying elements. While many HEAs have been shown to have unique\nproperties, their discovery has been largely done through costly and\ntime-consuming trial-and-error approaches, with only an infinitesimally small\nfraction of the entire possible composition space having been explored. In this\nwork, the exploration of the HEA composition space is framed as a Continuous\nConstraint Satisfaction Problem (CCSP) and solved using a novel Constraint\nSatisfaction Algorithm (CSA) for the rapid and robust exploration of alloy\nthermodynamic spaces. The algorithm is used to discover regions in the HEA\nComposition-Temperature space that satisfy desired phase constitution\nrequirements. The algorithm is demonstrated against a new (TCHEA1) CALPHAD HEA\nthermodynamic database. The database is first validated by comparing phase\nstability predictions against experiments and then the CSA is deployed and\ntested against design tasks consisting of identifying not only single phase\nsolid solution regions in ternary, quaternary and quinary composition spaces\nbut also the identification of regions that are likely to yield\nprecipitation-strengthened HEAs.",
        "positive": "Oxygen-vacancy centers in Y3Al5O12 garnet crystals: electron\n  paramagnetic resonance and dielectric spectroscopy study: F+ center, an electron trapped at oxygen vacancy (VO), was investigated in\nthe oxygen deficient Y3Al5O12 (YAG) crystals by EPR. The measurements were\nperformed at temperatures 5-450 K and frequencies 9.4-350 GHz with using both\nthe continue wave and pulse EPR technique. The pulse electron-nuclear double\nresonance was applied to resolve the hyperfine interaction of the trapped\nelectron with surrounding nuclei. The measurements show that at low\ntemperatures, T < 50 K, EPR spectrum of the F+ center is anisotropic with g\nfactors in the range 1.999-1.988 and originates from three magnetically\ninequivalent positions of the center in garnet lattice according to different\ndirections of the Al(IV)-VO-Al(VI) chains, where Al(IV) and Al(VI) are the\ntetrahedral and octahedral Al sites, respectively. As the temperature\nincreases, the EPR spectrum becomes isotropic suggesting a motional averaging\nof the anisotropy due to motion of electron between neighboring oxygen\nvacancies. With further increase of the temperature to T > 200 K, we observed\ndelocalization of the electron into the conduction band with the activation\nenergy about 0.4-0.5 eV that resulted in substantial narrowing of the EPR\nspectral line with simultaneous change of its shape from the Gaussian to\nLorentzian due to diminish up to zero of the Fermi contact hyperfine field at\n27Al and 89Y nuclei. Such temperature behavior of the F+-center electron in YAG\nis completely similar to behavior of a donor electron in a semiconductor. Our\nfindings is further supported by measurements of the conductivity and\ndielectric properties. In particular, these data show that the conduction\nelectrons are not homogeneously distributed in the crystal: there are\nhigh-conductive regions separated by poorly-conductive dielectric layers. This\nleads to the so-called Maxwell-Wagner dielectric relaxation with huge apparent\ndielectric constant at low frequencies."
    },
    {
        "anchor": "Grain Boundary Properties of Elemental Metals: The structure and energy of grain boundaries (GBs) are essential for\npredicting the properties of polycrystalline materials. In this work, we use\nhigh-throughput density functional theory calculations workflow to construct\nthe Grain Boundary Database (GBDB), the largest database of DFT-computed grain\nboundary properties to date. The database currently encompasses 327 GBs of 58\nelemental metals, including 10 common twist or symmetric tilt GBs for\nbody-centered cubic (bcc) and face-centered cubic (fcc) systems and the\n$\\Sigma$7 [0001] twist GB for hexagonal close-packed (hcp) systems. In\nparticular, we demonstrate a novel scaled-structural template approach for HT\nGB calculations, which reduces the computational cost of converging GB\nstructures by a factor of $\\sim 3-6$. The grain boundary energies and work of\nseparation are rigorously validated against previous experimental and\ncomputational data. Using this large GB dataset, we develop an improved\npredictive model for the GB energy of different elements based on the cohesive\nenergy and shear modulus. The open GBDB represent a significant step forward in\nthe availability of first principles GB properties, which we believe would help\nguide the future design of polycrystalline materials.",
        "positive": "Electrical tuning of spin splitting in Bi-doped ZnO nanowires: The effect of applying an external electric field on doping-induced\nspin-orbit splitting of the lowest conduction-band states in a bismuth-doped\nzinc oxide nanowire is studied by performing electronic structure calculations\nwithin the framework of density functional theory. It is demonstrated that spin\nsplitting in Bi-doped ZnO nanowires could be tuned and enhanced electrically\nvia control of the strength and direction of the applied electric field, thanks\nto the nonuniform and anisotropic response of the ZnO:Bi nanowire to external\nelectric fields. The results reported here indicate that a single ZnO nanowire\ndoped with a low concentration of Bi could function as a spintronic device,\noperation of which is controlled by applied lateral electric fields."
    },
    {
        "anchor": "A Multi-Technique Study of $CO_2$ Adsorption on $Fe_3$$O_4$ Magnetite: The adsorption of $CO_2$ on the $Fe_3$$O_4$(001)-($\\sqrt{2}$ $\\times$\n$\\sqrt{2}$)R45{\\deg} surface was studied experimentally using temperature\nprogrammed desorption (TPD), electron spectroscopies (UPS and XPS), and\nscanning tunneling microscopy (STM). $CO_2$ binds most strongly at defects\nrelated to Fe2+ including antiphase domain boundaries in the surface\nreconstruction and above incorporated Fe interstitials. On the pristine\nsurface, $CO_2$ adsorbs molecularly at fivefold-coordinated Fe3+ sites with a\nbinding energy of 0.4 eV. Above a coverage of 4 molecules per ($\\sqrt{2}$\n$\\times$ $\\sqrt{2}$)R45{\\deg} unit cell, further adsorption results in a\ncompression of the first monolayer up to a density approaching that of a $CO_2$\nice layer. Surprisingly, desorption of the second monolayer occurs at a lower\ntemperature ($\\approx$ 84 K) than $CO_2$ multilayers ($\\approx$ 88 K),\nsuggestive of a metastable phase or diffusion-limited island growth. The paper\nalso discusses design considerations for a vacuum system optimized to study the\nsurface chemistry of metal oxide single crystals, including the calibration and\ncharacterisation of a molecular beam source for quantitative TPD measurements.",
        "positive": "Current-driven domain wall motion along ferromagnetic strips with\n  periodically-modulated perpendicular anisotropy: The dynamics of magnetic domain walls along ferromagnetic strips with\nspatially modulated perpendicular magnetic anisotropy is theoretically studied\nby means of micromagnetic simulations. Ferromagnetic layers with a periodic\nsawtooth profile of the anisotropy depict a well-defined set of energy minima\nwhere the walls are pinned in the absence of external stimuli, and favor the\nunidirectional propagation of domain walls. The performance of the\ncurrent-driven domain wall motion along these ratchet-like systems is compared\nto the field-driven case. Our study indicates that the current-driven domain\nwall motion exhibits significant improvements with respect to the field-driven\ncase in terms of bit shifting speed and storage density, and therefore, it is\nsuggested for the development of novel devices. The feasibility of these\ncurrent-driven ratchet devices is studied by means of realistic micromagnetic\nsimulations and supported by a one-dimensional model updated to take into\naccount the periodic sawthooth anisotropy profile. Finally, the current-driven\ndomain wall motion is also evaluated in systems with a triangular modulation of\nthe anisotropy designed to promote the bidirectional shifting of series of\nwalls, a functionality that cannot be achieved by magnetic fields."
    },
    {
        "anchor": "Anomalous Hall effect arising from noncollinear antiferromagnetism: In most conductors current flow perpendicular to electric field direction\n(Hall current) can be explained in terms of the Lorentz forces present when\ncharged particles flow in an external magnetic field. However, as established\nin the very early work of Edwin Hall, ferromagnetic conductors such as Fe, Co,\nand Ni have an anomalous Hall conductivity contribution that cannot be\nattributed to Lorentz forces and therefore survives in the absence of a\nmagnetic field. Although the anomalous Hall effect is experimentally strong, it\nhas stood alone among metallic transport effects for much of the last century\nbecause it lacked a usefully predictive, generally accepted theory. Progress\nover the past decade has explained why. It is now clear that the anomalous Hall\neffect in ferromagnets has contributions from both extrinsic scattering\nmechanisms similar to those that determine most transport coefficients, and\nfrom an intrinsic mechanism that is independent of scattering. The anomalous\nHall effect is also observed in paramagnets, which have nonzero magnetization\ninduced by an external magnetic field. Although no explicit relationship has\nbeen established, the anomalous Hall effect in a particular material is usually\nassumed to be proportional to its magnetization. In this work we point out that\nit is possible to have an anomalous Hall effect in a noncollinear\nantiferromagnet with zero net magnetization provided that certain common\nsymmetries are absent, and predict that Mn3Ir, a technologically important\nantiferromagnetic material with noncollinear order that survives to very high\ntemperatures, has a surprisingly large anomalous Hall effect comparable in size\nto those of the elemental transition metal ferromagnets.",
        "positive": "Predictors of cavitation in glassy polymers under tensile strain: a\n  coarse grained molecular dynamics investigation: The nucleation of cavities in a homogenous polymer under tensile strain is\ninvestigated in a coarse-grained molecular dynamics simulation. In order to\nestablish a causal relation between local microstructure and the onset of\ncavitation, a detailed analysis of some local properties is presented. In\ncontrast to common assumptions, the nucleation of a cavity is neither\ncorrelated to a local loss of density nor, to the stress at the atomic scale\nand nor to the chain ends density in the undeformed state. Instead, a cavity in\nglassy polymers nucleates in regions that display a low bulk elastic modulus.\nThis criterion allows one to predict the cavity position before the cavitation\noccurs. Even if the localization of a cavity is not directly predictable from\nthe initial configuration, the elastically weak zones identified in the initial\nstate emerge as favorite spots for cavity formation."
    },
    {
        "anchor": "Criticality of Vacancy-Induced Metal-Insulator Transition in Graphene: The criticality of vacancy-induced metal-insulator transition (MIT) in\ngraphene is investigated by Kubo-Greenwood formula with tight-binding recursion\nmethod. The critical vacancy concentration for the MIT is determined to be\n0.053%. The scaling laws for transport properties near the critical point are\nexamined showing several unconventional 2D localization behaviors. Our\ntheoretical results have shed some new lights to the understanding of recent\nexperiments in H-dosed graphene and of 2D disordered systems in general.",
        "positive": "Room-Temperature Structures of Solid Hydrogen at High Pressures: By employing first-principles metadynamics simulations, we explore the 300 K\nstructures of solid hydrogen over the pressure range 150-300 GPa. At 200 GPa,\nwe find the ambient-pressure disordered hexagonal close-packed (hcp) phase\ntransited into an insulating partially ordered hcp phase (po-hcp), a mixture of\nordered graphene-like H2 layers and the other layers of weakly coupled,\ndisordered H2 molecules. Within this phase, hydrogen remains in paired states\nwith creation of shorter intra-molecular bonds, which are responsible for the\nvery high experimental Raman peak above 4000 cm-1. At 275 GPa, our simulations\npredicted a transformation from po-hcp into the ordered molecular metallic Cmca\nphase (4 molecules/cell) that was previously proposed to be stable only above\n400 GPa. Gibbs free energy calculations at 300 K confirmed the energetic\nstabilities of the po-hcp and metallic Cmca phases over all known structures at\n220-242 GPa and >242 GPa, respectively. Our simulations highlighted the major\nrole played by temperature in tuning the phase stabilities and provided\ntheoretical support for claimed metallization of solid hydrogen below 300 GPa\nat 300 K."
    },
    {
        "anchor": "Unique determination of localized basis in molecular spin: Localized basis plays an important role in comprehending the magnetic\ndynamics in molecular spins from a physics perspective. Nonetheless, the\nuniqueness and rigor of its determination have received limited attention. In\nthis study, we propose a new determination of the localized basis applicable to\nboth non-Kramers and Kramers molecular spin systems, leveraging the\ntime-reversal symmetry of the spin Hamiltonian and the molecular spin's main\nmagnetic axis. By introducing this, we establish a distinct and practical means\nof determining the localized basis, enabling the association of a molecular\nspin wave function with either an \"up\" or \"down\" magnetic moment orientation in\nmolecular spins. This finding facilitates a comprehensive interpretation of\nmagnetic dynamics and simplifies the construction of theoretical models for\nmaterials analysis.",
        "positive": "Thermoelectric Devices: Principles and Future Trends: The principles of the thermoelectric phenomenon, including Seebeck effect,\nPeltier effect, and Thomson effect are discussed. The dependence of the\nthermoelectric devices on the figure of merit, Seebeck coefficient, electrical\nconductivity, and thermal conductivity are explained in details. The paper\nprovides an overview of the different types of thermoelectric materials,\nexplains the techniques used to grow thin films for these materials, and\ndiscusses future research and development trends for this technology."
    },
    {
        "anchor": "Semimetal-semiconductor transition and giant linear magnetoresistances\n  in three-dimensional Dirac semimetal Bi0.96Sb0.04 single crystals: Three-dimensional (3D) Dirac semimetals are new quantum materials and can be\nviewed as 3D analogues of graphene. Many fascinating electronic properties have\nbeen proposed and realized in 3D Dirac semimetals, which demonstrates their\npotential applications in next generation quantum devices. Bismuth-antimony\nBi1-xSbx can be tuned from a topological insulator to a band insulator through\na quantum critical point at x ~ 4%, where 3D Dirac fermions appear. Here, we\nreport on a magnetotransport study of Bi1-xSbx at such a quantum critical\npoint. An unusual magnetic-field induced semimetal-semiconductor phase\ntransition was observed in the Bi0.96Sb0.04 single crystals. In a magnetic\nfield of 8 T, Bi0.96Sb0.04 single crystals show giant magnetoresistances of up\nto 6000% at low-temperature, 5 K, and 300% at room-temperature, 300 K. The\nobserved magnetoresistances keep linear down to approximate zero-field when the\ntemperature is below 200 K. Our experimental results are not only interesting\nfor the fundamental physics of 3D Dirac semimetals, but also for potential\napplications of 3D Dirac semimetals in magnetoelectronic devices.",
        "positive": "Anomalous anisotropy of spin current in a cubic spin source with\n  noncollinear antiferromagnetism: Cubic materials host high crystal symmetry and hence are not expected to\nsupport anisotropy in transport phenomena. In contrast to this common\nexpectation, here we report an anomalous anisotropy of spin current can emerge\nin the (001) film of Mn${_3}$Pt, a noncollinear antiferromagnetic spin source\nwith face-centered cubic structure. Such spin current anisotropy originates\nfrom the intertwined time reversal-odd ($T$-odd) and time reversal-even\n($T$-even) spin Hall effects. Based on symmetry analyses and experimental\ncharacterizations of the current-induced spin torques in Mn${_3}$Pt-based\nheterostructures, we find that the spin current generated by Mn${_3}$Pt (001)\nexhibits exotic dependences on the current direction for all the spin\ncomponents, deviating from that in conventional cubic systems. We also\ndemonstrate that such an anisotropic spin current can be used to realize\nlow-power spintronic applications such as the efficient field-free switching of\nthe perpendicular magnetizations."
    },
    {
        "anchor": "Improving the applicability of the Pauli kinetic energy density based\n  semilocal functional for solids: The Pauli kinetic energy enhancement factor\n$\\alpha=(\\tau-\\tau^W)/\\tau^{unif}$ is an important density ingredient, used to\nconstruct many meta-generalized gradient approximations (meta-GGA)\nexchange-correlation (XC) energy functionals, including the very successful\nstrongly constrained and appropriately normed (SCAN) semilocal functional.\nAnother meta-GGA functional, known as MGGAC [Phys. Rev. B 100, 155140 (2019)],\nis also proposed in recent time depending only on the $\\alpha$ ingredient and\nbased on the generalization of the Becke-Roussel approach with the cuspless\nhydrogen exchange hole density. The MGGAC functional is proved to be a very\nuseful and competitive meta-GGA semilocal functional for electronic structure\nproperties of solids and molecules. Based on the successful implication of the\ningredient $\\alpha$, which is also useful to construct the one-electron\nself-interaction free correlation energy functional, here we propose revised\ncorrelation energy for MGGAC exchange functional which is more accurate and\nrobust, especially for the high and low-density limits of the uniform density\nscaling. The present XC functional, named as revised MGGAC (rMGGAC), shows an\nimpressive improvement for the structural and energetic properties of solids\ncompared to its previous version. Moreover, the assessment of the present\nconstructed functional shows to be quite useful in solid-state physics in terms\nof addressing several current challenging solid-state problems.",
        "positive": "An ab-initio converse NMR approach for pseudopotentials: We extend the recently developed converse NMR approach [T. Thonhauser, D.\nCeresoli, A. Mostofi, N. Marzari, R. Resta, and D. Vanderbilt, J. Chem. Phys.\n\\textbf{131}, 101101 (2009)] such that it can be used in conjunction with\nnorm-conserving, non-local pseudopotentials. This extension permits the\nefficient ab-initio calculation of NMR chemical shifts for elements other than\nhydrogen within the convenience of a plane-wave pseudopotential approach. We\nhave tested our approach on several finite and periodic systems, finding very\ngood agreement with established methods and experimental results."
    },
    {
        "anchor": "Thermal spin-transfer in Fe-MgO-Fe tunnel junctions: We compute thermal spin transfer torques (TST) in Fe-MgO-Fe tunnel junctions\nusing a first principles wave function-matching method. At room temperature,\nthe TST in a junction with 3 MgO monolayers amounts to 10^-7J/m^2/K, which is\nestimated to cause magnetization reversal for temperature differences over the\nbarrier of the order of 10 K. The large TST can be explained by multiple\nscattering between interface states through ultrathin barriers. The angular\ndependence of the TST can be very skewed, possibly leading to thermally induced\nhigh-frequency generation.",
        "positive": "Electronic bulk and domain wall properties in B-site doped hexagonal\n  ErMnO$_3$: Acceptor and donor doping is a standard for tailoring semiconductors. More\nrecently, doping was adapted to optimize the behavior at ferroelectric domain\nwalls. In contrast to more than a century of research on semiconductors, the\nimpact of chemical substitutions on the local electronic response at domain\nwalls is largely unexplored. Here, the hexagonal manganite ErMnO$_3$ is donor\ndoped with Ti$^{4+}$. Density functional theory calculations show that\nTi$^{4+}$ goes to the B-site, replacing Mn$^{3+}$. Scanning probe microscopy\nmeasurements confirm the robustness of the ferroelectric domain template. The\nelectronic transport at both macro- and nanoscopic length scales is\ncharacterized. The measurements demonstrate the intrinsic nature of emergent\ndomain wall currents and point towards Poole-Frenkel conductance as the\ndominant transport mechanism. Aside from the new insight into the electronic\nproperties of hexagonal manganites, B-site doping adds an additional degree of\nfreedom for tuning the domain wall functionality."
    },
    {
        "anchor": "Improved reconstructions of random media using dilation and erosion\n  processes: By using the most sensitive two-point correlation functions introduced to\ndate, we reconstruct the microstructures of two-phase random media with\nheretofore unattained accuracy. Such media arise in a host of contexts,\nincluding porous and composite media, ecological structures, biological media,\nand astrophysical structures. The aforementioned correlation functions are\nspecial cases of the so-called {\\it canonical} $n$-point correlation function\n$H_n$ and generalize the ones that have been recently employed to advance our\nability to reconstruct complex microstructures [Y. Jiao, F. H. Stillinger, and\nS. Torquato, Proc. Nat. Acad. Sci. {\\bf 106}, 17634 (2009)]. The use of these\ngeneralized correlation functions is tantamount to dilating or eroding a\nreference phase of the target medium and incorporating the additional\ntopological information of the modified media, thereby providing more accurate\nreconstructions of percolating, filamentary, and other topologically complex\nmicrostructures. We apply our methods to a multiply-connected \"donut\" medium\nand a dilute distribution of \"cracks\" (a set of essentially zero measure)\ndemonstrating improved accuracy in both cases with implications for\nhigher-dimensional and biconnected two-phase systems. The high information\ncontent of the generalized two-point correlation functions suggests that it\nwould be profitable to explore their use to characterize the structural and\nphysical properties of not only random media, but also molecular systems,\nincluding structural glasses.",
        "positive": "Inorganic synthesis-structure maps in zeolites with machine learning and\n  crystallographic distances: Zeolites are inorganic materials known for their diversity of applications,\nsynthesis conditions, and resulting polymorphs. Although their synthesis is\ncontrolled both by inorganic and organic synthesis conditions, computational\nstudies of zeolite synthesis have focused mostly on organic template design. In\nthis work, we use a strong distance metric between crystal structures and\nmachine learning (ML) to create inorganic synthesis maps in zeolites. Starting\nwith 253 known zeolites, we show how the continuous distances between\nframeworks reproduce inorganic synthesis conditions from the literature without\nusing labels such as building units. An unsupervised learning analysis shows\nthat neighboring zeolites according to our metric often share similar inorganic\nsynthesis conditions, even in template-based routes. In combination with ML\nclassifiers, we find synthesis-structure relationships for 14 common inorganic\nconditions in zeolites, namely Al, B, Be, Ca, Co, F, Ga, Ge, K, Mg, Na, P, Si,\nand Zn. By explaining the model predictions, we demonstrate how\n(dis)similarities towards known structures can be used as features for the\nsynthesis space. Finally, we show how these methods can be used to predict\ninorganic synthesis conditions for unrealized frameworks in hypothetical\ndatabases and interpret the outcomes by extracting local structural patterns\nfrom zeolites. In combination with template design, this work can accelerate\nthe exploration of the space of synthesis conditions for zeolites."
    },
    {
        "anchor": "Revealing the role of organic cations in hybrid halide perovskites\n  CH3NH3PbI3: The hybrid halide perovskite CH$_{3}$NH$_{3}$PbI$_{3}$ has enabled solar\ncells to reach an efficiency of about 18\\%, demonstrating a pace for\nimprovements with no precedents in the solar energy arena. Despite such\nexplosive progress, the microscopic origin behind the success of such material\nis still debated, with the role played by the organic cations in the\nlight-harvesting process remaining unclear. Here van-der-Waals-corrected\ndensity functional theory calculations reveal that the orientation of the\norganic molecules plays a fundamental role in determining the material\nelectronic properties. For instance, if CH$_{3}$NH$_{3}$ orients along a\n(011)-like direction, the PbI$_{6}$ octahedral cage will distort and the band\ngap will become indirect. Our results suggest that molecular rotations, with\nthe consequent dynamical change of the band structure, might be at the origin\nof the slow carrier recombination and the superior conversion efficiency of\nCH$_{3}$NH$_{3}$PbI$_{3}$.",
        "positive": "Rapid Domain Wall Motion in Permalloy Nanowires Excited by\n  Spin-Polarized Current Applied Perpendicular to the Nanowire: We study domain wall (DW) dynamics in permalloy nanowires excited by\nalternating spin-polarized current applied perpendicular to the nanowire. Spin\ntorque ferromagnetic resonance measurements reveal that DW oscillations at a\npinning site in the nanowire can be excited with velocities as high as 800 m/s\nat current densities below 10$^7$ A/cm$^2$."
    },
    {
        "anchor": "Determination of the intrinsic anomalous Hall effect of SrRuO$_3$: The anomalous Hall effect (AHE) of epitaxial SrRuO$_3$ films with varying\nlattice parameters is investigated, and analyzed according to the Berry-phase\nscenario. SrRuO$_3$ thin films were deposited on SrTiO$_3$ substrates directly,\nor using intermediate buffer layers, in order to finely control the epitaxial\nstrain. The AHE of the different films exhibits intrinsic features such as the\nsign change of the Hall resistivity with the temperature, even for small\nthicknesses of SrRuO$_3$. However, the anomalous Hall conductivity is greatly\nreduced from its intrinsic value as the carrier scattering is increased when\nthe epitaxial strain is released. We argue that the AHE of fully strained\nSrRuO$_3$ film with low residual resistivity represents the intrinsic AHE of\nSrRuO$_3$.",
        "positive": "Hard x-ray standing-wave photoemission insights into the structure of an\n  epitaxial Fe/MgO multilayer magnetic tunnel junction: The Fe/MgO magnetic tunnel junction is a classic spintronic system, with\ncurrent importance technologically, and interest for future innovation. The key\nmagnetic properties are linked directly to the structure of hard-to-access\nburied interfaces, and the Fe and MgO components near the surface are unstable\nwhen exposed to air, making a deeper probing, non-destructive, in-situ\nmeasurement ideal for this system. We have thus applied hard x-ray\nphotoemission spectroscopy (HXPS) and standing-wave (SW) HXPS in the few keV\nenergy range to probe the structure of an epitaxially-grown MgO/Fe\nsuperlattice. The superlattice consists of 9 repeats of MgO grown on Fe by\nmagnetron sputtering on an MgO (001) substrate, with a protective Al2O3 capping\nlayer. We determine through SW-HXPS that 8 of the 9 repeats are similar and\nordered, with a period of 33 $\\pm$ 4 angstrom, with minor presence of FeO at\nthe interfaces and a significantly distorted top bilayer with ca. 3 times the\noxidation of the lower layers at the top MgO/Fe interface. There is evidence of\nasymmetrical oxidation on the top and bottom of the Fe layers. We find\nagreement with dark-field scanning transmission electron microscope (STEM) and\nx-ray reflectivity measurements. Through the STEM measurements we confirm an\noverall epitaxial stack with dislocations and warping at the interfaces of ca.\n5 angstrom. We also note a distinct difference in the top bilayer, especially\nMgO, with possible Fe inclusions. We thus demonstrate that SW-HXPS can be used\nto probe deep buried interfaces of novel magnetic devices with few angstrom\nprecision."
    },
    {
        "anchor": "Vacancy defects induced changes in the electronic and optical properties\n  of NiO studied by spectroscopic ellipsometry and first-principles\n  calculations: Native defects in semiconductors play an important role in their\noptoelectronic properties. Nickel oxide (NiO) is one of the few wide-gap p-type\noxide semiconductors and its conductivity is believed to be controlled\nprimarily by Ni-vacancy acceptors. Herein, we present a systematic study\ncomparing the optoelectronic properties of stoichiometric NiO, oxygen-rich NiO\nwith Ni vacancies (NiO:VNi), and Ni-rich NiO with O vacancies (NiO:VO). The\noptical properties were obtained by spectroscopic ellipsometry, while valence\nband spectra were probed by high-resolution x-ray photoelectron spectroscopy.\nThe experimental results are directly compared to first-principles density\nfunctional theory + U calculations. Computational results confirm that gap\nstates are present in both NiO systems with vacancies. Gap states in NiO:Vo are\npredominantly Ni 3d states, while those in NiO:VNi are composed of both Ni 3d\nand O 2p states. The absorption spectra of the NiO:VNi sample show significant\ndefect-induced features below 3.0 eV compared to NiO and NiO:VO samples. The\nincrease in sub-gap absorptions in NiO:VNi can be attributed to gap states\nobserved in the electronic density of states. The relation between native\nvacancy defects and electronic and optical properties of NiO are demonstrated,\nshowing that at similar vacancy concentration, the optical constants of NiO:VNi\ndeviate significantly from those of NiO:VO. Our experimental and computational\nresults reveal that although VNi are effective acceptors in NiO, they also\ndegrade the visible transparency of the material. Hence, for transparent\noptoelectronic device applications, an optimization of native VNi defects with\nextrinsic doping is required to simultaneously enhance p-type conductivity and\ntransparency.",
        "positive": "Exploration of growth conditions of TaAs Weyl semimetal thin film by\n  pulsed laser deposition: TaAs, the first experimentally discovered Weyl semimetal material, has\nattracted a lot of attention due to its high carrier mobility, high anisotropy,\nnonmagnetic and strong interaction with light. These make it an ideal candidate\nfor the study of Weyl fermions and the applications in quantum computation,\nthermoelectric devices, and photodetection. For further basic physics studies\nand potential applications, large-size and high-quality TaAs films are urgently\nneeded. However, it is difficult to grow As-stoichiometry TaAs films due to the\nvolatilization of As during the growth. To solve this problem, the TaAs films\nwere attempted to grow on different substrates using targets with different As\nstoichiometric ratios by pulsed laser deposition (PLD). In this work, we have\nfound that partial As ions of the GaAs substrate are likely to diffuse into the\nTaAs films during growth, which was preliminarily confirmed by the structural\ncharacterization, surface topography and composition analysis. As a result, the\nAs content in the TaAs film is improved and the TaAs phase is achieved. Our\nwork presents an effective method to fabricate the TaAs films by PLD, providing\nthe possible use of the Weyl semimetal film for functional devices."
    },
    {
        "anchor": "Autonomous data-driven design of inorganic materials with AFLOW: The expansion of programmatically-accessible materials data has cultivated\nopportunities for data-driven approaches. Highly-automated frameworks like\nAFLOW not only manage the generation, storage, and dissemination of materials\ndata, but also leverage the information for thermodynamic formability modeling,\nsuch as the prediction of phase diagrams and properties of disordered\nmaterials. In combination with standardized parameter sets, the wealth of data\nis ideal for training machine learning algorithms, which have already been\nemployed for property prediction, descriptor development, design rule\ndiscovery, and the identification of candidate functional materials. These\nmethods promise to revolutionize the path to synthesis and, ultimately,\ntransform the practice of traditional materials discovery to one of rational\nand autonomous materials design.",
        "positive": "Binding between endohedral Na atoms in Si clathrate I; a first\n  principles study: We investigate the binding nature of the endohedral sodium atoms with the\nensity functional theory methods, presuming that the clathrate I consists of a\nsheaf of one-dimensional connections of Na@Si$_{24}$ cages interleaved in three\nperpendicular directions. Each sodium atom loses 30% of the 3s$^1$ charge to\nthe frame, forming an ionic bond with the cage atoms; the rest of the electron\ncontributes to the covalent bond between the nearest Na atoms. The presumption\nis proved to be valid; the configuration of the two Na atoms in the nearest\nSi$_{24}$ cages is more stable by 0.189 eV than that in the Si$_{20}$ and\nSi$_{24}$ cages. The energy of the beads of the two distorted Na atoms is more\nstable by 0.104 eV than that of the two infinitely separated Na atoms. The\ncovalent bond explains both the preferential occupancies in the Si$_{24}$ cages\nand the low anisotropic displacement parameters of the endohedral atoms in the\nSi$_{24}$ cages in the [100] directions of the clathrate I."
    },
    {
        "anchor": "Band structures and $\\mathbb{Z}_2$ invariants of two-dimensional\n  transition metal dichalcogenide monolayers from fully-relativistic\n  Dirac-Kohn-Sham theory using Gaussian-type orbitals: Two-dimensional (2D) materials exhibit a wide range of remarkable phenomena,\nmany of which owe their existence to the relativistic spin-orbit coupling (SOC)\neffects. To understand and predict properties of materials containing heavy\nelements, such as the transition-metal dichalcogenides (TMDs), relativistic\neffects must be taken into account in first-principles calculations. We present\nan all-electron method based on the four-component Dirac Hamiltonian and\nGaussian-type orbitals (GTOs) that overcomes complications associated with\nlinear dependencies and ill-conditioned matrices that arise when diffuse\nfunctions are included in the basis. Until now, there has been no systematic\nstudy of the convergence of GTO basis sets for periodic solids either at the\nnonrelativistic or the relativistic level. Here we provide such a study of\nrelativistic band structures of the 2D TMDs in the hexagonal (2H), tetragonal\n(1T), and distorted tetragonal (1T') structures, along with a discussion of\ntheir SOC-driven properties (Rashba splitting and $\\mathbb{Z}_2$ topological\ninvariants). We demonstrate the viability of our approach even when large basis\nsets with multiple basis functions involving various valence orbitals (denoted\ntriple- and quadruple-$\\zeta$) are used in the relativistic regime. Our method\ndoes not require the use of pseudopotentials and provides access to all\nelectronic states within the same framework. Our study paves the way for direct\nstudies of material properties, such as the parameters in spin Hamiltonians,\nthat depend heavily on the electron density near atomic nuclei where\nrelativistic and SOC effects are the strongest.",
        "positive": "A simple descriptor and predictor for the stable structures of\n  two-dimensional surface alloys: Predicting the ground state of alloy systems is challenging due to the large\nnumber of possible configurations. We identify an easily computed descriptor\nfor the stability of binary surface alloys, the effective coordination number\n$\\mathscr{E}$. We show that $\\mathscr{E}(M)$ correlates well with the enthalpy\nof mixing, from density functional theory (DFT) calculations on\n$M_x$Au$_{1-x}$/Ru [$M$ = Mn or Fe]. At each $x$, the most favored structure\nhas the highest [lowest] value of $\\mathscr{E}(M)$ if the system is\nnon-magnetic [ferromagnetic]. Importantly, little accuracy is lost upon\nreplacing $\\mathscr{E}(M)$ by $\\mathscr{E}^*(M)$, which can be quickly computed\nwithout performing a DFT calculation, possibly offering a simple alternative to\nthe frequently used cluster expansion method."
    },
    {
        "anchor": "Interband Tunneling in 2D Crystal Semiconductors: Interband quantum tunneling of electrons in semiconductors is of intense\nrecent interest as the underlying transport mechanism in tunneling field-effect\ntransistors. Such transistors can potentially perform electronic switching with\nlower energy than their conventional counterparts. The recent emergence of\n2-dimensional semiconducting crystals provides a new material platform for\nrealizing such devices. In this work, we derive an analytical expression for\nunderstanding tunneling current flow in 2D crystal semiconductors. We apply the\nresults to a range of 2D crystal semiconductors, and compare it with tunneling\ncurrents in 3D semiconductors. We also discuss the implications for tunneling\ndevices.",
        "positive": "Magnetic stress as a driving force of structural distortions: the case\n  of CrN: We show that the observed transition from rocksalt to orthorhombic P$_{nma}$\nsymmetry in CrN can be understood in terms of stress anisotropy. Using local\nspin density functional theory, we find that the imbalance between stress\nstored in spin-paired and spin-unpaired Cr nearest neighbors causes the\nrocksalt structure to be unstable against distortions and justifies the\nobserved antiferromagnetic ordering. This stress has a purely magnetic origin,\nand may be important in any system where the coupling between spin ordering and\nstructure is strong."
    },
    {
        "anchor": "Interlayer and interfacial exchange coupling in ferromagnetic\n  metal/semiconductor heterostructures: We describe a systematic study of the exchange coupling between a\nmagnetically hard metallic ferromagnet (MnAs) and a magnetically soft\nferromagnetic semiconductor (GaMnAs) in bilayer and trilayer heterostructures.\nAn exchange spring model of MnAs/GaMnAs bilayers accounts for the variation of\nthe exchange bias field with layer thickness and composition. We also present\nevidence for hole-mediated interlayer exchange coupling in MnAs/p-GaAs/\\GaMnAs\ntrilayers and study the dependence of the exchange bias field on the thickness\nof the spacer layer.",
        "positive": "Effects of high-pressure on the structural, vibrational, and electronic\n  properties of monazite-type PbCrO4: We have performed an experimental study of the crystal structure,\nlattice-dynamics, and optical properties of PbCrO4 (the mineral crocoite) at\nambient and high pressures. In particular, the crystal structure, Raman-active\nphonons, and electronic band-gap have been accurately determined.\nX-ray-diffraction, Raman, and optical-absorption experiments have allowed us\nalso to completely characterize two pressure-induced structural phase\ntransitions. The first transition is isostructural, maintaining the monoclinic\nsymmetry of the crystal, and having important consequences in the physical\nproperties; among other a band-gap collapse is induced. The second one involves\nan increase of the symmetry of the crystal, a volume collapse, and probably the\nmetallization of PbCrO4. The results are discussed in comparison with related\ncompounds and the effects of pressure in the electronic structure explained.\nFinally, the room-temperature equation of state of the low-pressure phases is\nalso obtained."
    },
    {
        "anchor": "Mapping the spin-dependent electron reflectivity of Fe and Co\n  ferromagnetic thin films: Spin Polarized Low Energy Electron Microscopy is used as a spin dependent\nspectroscopic probe to study the spin dependent specular reflection of a\npolarized electron beam from two different magnetic thin film systems:\nFe/W(110) and Co/W(110). The reflectivity and spin-dependent\nexchange-scattering asymmetry are studied as a function of electron kinetic\nenergy and film thickness, as well as the time dependence. The largest value of\nthe figure of merit for spin polarimetry is observed for a 5 monolayer thick\nfilm of Co/W(110) at an electron kinetic energy of 2eV. This value is 2 orders\nof magnitude higher than previously obtained with state of the art Mini-Mott\npolarimeter. We discuss implications of our results for the development of an\nelectron-spin-polarimeter using the exchange-interaction at low energy.",
        "positive": "Compositional descriptor-based recommender system accelerating the\n  materials discovery: Structures and properties of many inorganic compounds have been collected\nhistorically. However, it only covers a very small portion of possible\ninorganic crystals, which implies the presence of numerous currently unknown\ncompounds. A powerful machine-learning strategy is mandatory to discover new\ninorganic compounds from all chemical combinations. Herein we propose a\ndescriptor-based recommender-system approach to estimate the relevance of\nchemical compositions where stable crystals can be formed [i.e., chemically\nrelevant compositions (CRCs)]. As well as data-driven compositional similarity\nused in the literature, the use of compositional descriptors as a prior\nknowledge can accelerate the discovery of new compounds. We validate our\nrecommender systems in two ways. Firstly, one database is used to construct a\nmodel, while another is used for the validation. Secondly, we estimate the\nphase stability for compounds at expected CRCs using density functional theory\ncalculations."
    },
    {
        "anchor": "Analytic prediction of yield stress and strain hardening in a strain\n  gradient plasticity material reinforced by small elastic particles: The influence on macroscopic work hardening of small, spherical, elastic\nparticles dispersed within a matrix is studied using an isotropic strain\ngradient plasticity framework. An analytical solution, based on a recently\ndeveloped yield strength model is proposed. The model accounts for random\nvariations in particle size and elastic properties, and is numerically\nvalidated against FE solutions in 2D/3D material cell models. Excellent\nagreement is found as long as the typical particle radius is much smaller than\nthe material length scale, given that the particle volume fraction is not too\nlarge ($<10\\%$) and that the particle/matrix elastic mismatch is within a\nrealistic range. Finally, the model is augmented to account for strengthening\ncontribution from shearable particles using classic line tension models and\nsuccessfully calibrated against experimental tensile data on an\n$Al-2.8wt\\%Mg-0.16wt\\%Sc$ alloy.",
        "positive": "General degeneracy in density functional perturbation theory: Degenerate perturbation theory from quantum mechanics is inadequate in\ndensity functional theory (DFT) because of nonlinearity in the Kohn-Sham\npotential. Herein, we develop the fully general perturbation theory for\nopen-shell, degenerate systems in Kohn-Sham DFT, without assuming the presence\nof symmetry or equal occupation of degenerate orbitals. To demonstrate the\nresulting methodology, we apply it to the iron atom in the central field\napproximation, perturbed by an electric quadrupole. This system was chosen\nbecause it displays both symmetry required degeneracy, between the five\n3\\textit{d} orbitals, as well as accidental degeneracy, between the 3\\textit{d}\nand 4\\textit{s} orbitals. The quadrupole potential couples the degenerate\n3\\textit{d} and 4\\textit{s} states, serving as an example of the most general\nperturbation."
    },
    {
        "anchor": "Generalized Method for Charge Transfer Equilibration in Reactive\n  Molecular Dynamics: Variable charge models (e.g., EEM, QEq, ES+) in reactive molecular dynamics\nsimulations often inherently impose a global charge transfer between atoms\n(approximating each system as ideal metal). Consequently, most surface\nprocesses (e.g., adsorption, desorption, deposition, sputtering) are affected,\npotentially causing dubious dynamics. This issue is meant to be addressed by\nthe ACKS2 and QTPIE model, which are based on the Kohn-Sham density functional\ntheory as well as a charge transfer restricting extension to the QEq model\n(approximating each system as ideal insulator), respectively. In a brief review\nof the QEq and the QTPIE model, their applicability for studying surface\ninteractions is assessed in this work. Following this reasoning, the demand for\na revised generalization of the QEq and QTPIE model is proposed, called charge\ntransfer equilibration model or in short QTE model. This method is derived from\nthe equilibration of constrained charge transfer variables, instead of\nconsidering atomic charge variables. The latter, however, are obtained by a\nrespective transformation, employing an extended Lagrangian method. We moreover\npropose a mirror boundary condition and its implementation to accelerate\nsurface investigations. The models proposed in this work facilitate reactive\nmolecular dynamics simulations which describe various materials and surface\nphenomena appropriately.",
        "positive": "Controlling the growth of Bi(110) and Bi(111) films on an insulating\n  substrate: Here we demonstrate the controlled growth of Bi(110) and Bi(111) films on an\n(insulating) $\\alpha$-Al$_2$O$_3$(0001) substrate by surface X-ray diffraction\nand X-ray reflectivity using synchrotron radiation. At temperatures as low as\n40 K, unanticipated pseudo-cubic Bi(110) films are grown having a thickness\nranging from a few to tens of nanometers. The roughness at the film-vacuum as\nwell as at the film-substrate interface, can be reduced by mild heating, where\na crystallographic orientation transition of Bi(110) towards Bi(111) is\nobserved at 400 K. From 450 K onwards high quality and ultrasmooth Bi(111)\nfilms are formed. Growth around the transition temperature results in the\ngrowth of competing Bi(110) and Bi(111) thin film domains."
    },
    {
        "anchor": "Many-body Green's function approaches to the doped Fr\u00f6hlich solid:\n  Exact solutions and anomalous mass enhancement: In polar semiconductors and insulators, the Fr\\\"ohlich interaction between\nelectrons and long-wavelength longitudinal optical phonons induces a many-body\nrenormalization of the carrier effective masses and the appearence of\ncharacteristic phonon sidebands in the spectral function, commonly dubbed\n'polaron satellites'. The simplest model that captures these effects is the\nFr\\\"ohlich model, whereby electrons in a parabolic band interact with a\ndispersionless longitudinal optical phonon. The Fr\\\"ohlich model has been\nemployed in a number of seminal papers, from early perturbation-theory\napproaches to modern diagrammatic Monte Carlo calculations. One limitation of\nthis model is that it focuses on undoped systems, thus ignoring carrier\nscreening and Pauli blocking effects that are present in real experiments on\ndoped samples. To overcome this limitation, we here extend the Fr\\\"ohlich model\nto the case of doped systems, and we provide exact solutions for the electron\nspectral function, mass enhancement, and polaron satellites. We perform the\nanalysis using two approaches, namely Dyson's equation with the Fan-Migdal\nself-energy, and the second-order cumulant expansion. We find that these two\napproaches provide qualitatively different results. In particular, the Dyson's\napproach yields better quasiparticle masses and worse satellites, while the\ncumulant approach provides better satellite structures, at the price of worse\nquasiparticle masses. Both approaches yield an anomalous enhancement of the\nelectron effective mass at finite doping levels, which in turn leads to a\nbreakdown of the quasiparticle picture in a significant portion of the phase\ndiagram.",
        "positive": "Topological Catastrophe and Isostructural Phase Transition in Calcium: We predict a quantum phase transition in fcc Ca under hydrostatic pressure.\nUsing density functional theory, we find at pressures below 80 kbar, the\ntopology of the electron charge density is characterized by nearest neighbor\natoms connected through bifurcated bond paths and deep minima in the octahedral\nholes. At pressures above 80 kbar, the atoms bond through non-nuclear maxima\nthat form in the octahedral holes. This topological change in the charge\ndensity softens the C' elastic modulus of fcc Ca, while C$_{44}$ remains\nunchanged. We propose an order parameter based on applying Morse theory to the\ncharge density, and we show that near the critical point it follows the\nexpected mean-field scaling law with reduced pressure."
    },
    {
        "anchor": "The Role of Interfacial Morphology in Cu2O/TiO2 and Band Bending:\n  Insights from Density Functional Theory: Photocatalysis, a promising solution for environmental challenges, relies on\nthe generation and utilization of photogenerated charge carriers within\nphotocatalysts. However, recombination of these carriers often limits\nefficiency. Heterostructures, especially Cu2O/TiO2, have emerged as effective\nsolutions to enhance charge separation. This study systematically explores the\neffect of interfacial morphologies on the band bending within Cu2O/TiO2 anatase\nheterostructures, employing density functional theory (DFT). Through this\nstudy, eight distinct interfaces are identified and analyzed, revealing a\nconsistent staggered-type band alignment. Despite variations in band edge\npositions, a systematic charge transfer from Cu2O to TiO2 is observed across\nall interfaces. The proposed band bending configurations would suggest enhanced\ncharge separation and photocatalytic activity under ultraviolet illumination\ndue to a Z-scheme configuration. This theoretical investigation provides\nvaluable insights into the interplay between interfacial morphology, band\nbending, and charge transfer, for advancing the understanding of fundamental\nelectronic mechanisms in heterostructures.",
        "positive": "Computational Discovery of Energy-Efficient Heat Treatment for\n  Microstructure Design using Deep Reinforcement Learning: Deep Reinforcement Learning (DRL) is employed to develop autonomously\noptimized and custom-designed heat-treatment processes that are both,\nmicrostructure-sensitive and energy efficient. Different from conventional\nsupervised machine learning, DRL does not rely on static neural network\ntraining from data alone, but a learning agent autonomously develops optimal\nsolutions, based on reward and penalty elements, with reduced or no\nsupervision. In our approach, a temperature-dependent Allen-Cahn model for\nphase transformation is used as the environment for the DRL agent, serving as\nthe model world in which it gains experience and takes autonomous decisions.\nThe agent of the DRL algorithm is controlling the temperature of the system, as\na model furnace for heat-treatment of alloys. Microstructure goals are defined\nfor the agent based on the desired microstructure of the phases. After\ntraining, the agent can generate temperature-time profiles for a variety of\ninitial microstructure states to reach the final desired microstructure state.\nThe agent's performance and the physical meaning of the heat-treatment profiles\ngenerated are investigated in detail. In particular, the agent is capable of\ncontrolling the temperature to reach the desired microstructure starting from a\nvariety of initial conditions. This capability of the agent in handling a\nvariety of conditions paves the way for using such an approach also for\nrecycling-oriented heat treatment process design where the initial composition\ncan vary from batch to batch, due to impurity intrusion, and also for the\ndesign of energy-efficient heat treatments. For testing this hypothesis, an\nagent without penalty on the total consumed energy is compared with one that\nconsiders energy costs. The energy cost penalty is imposed as an additional\ncriterion on the agent for finding the optimal temperature-time profile."
    },
    {
        "anchor": "Mapping the magnetic state as a function of anti-site disorder in Sm$\n  _{2} $NiMnO$ _{6} $ double perovskite thin films: The predictability of any characteristic functional aspect in a double\nperovskite system has always been compromised by its strong dependence over the\ninevitably present anti-site disorders (ASD). Here, we aim to precisely map the\nquantitative and qualitative nature of ASD with the corresponding modifications\nin observables describing the magnetic and electronic state in epitaxial Sm$\n_{2} $NiMnO$ _{6} $ (SNMO) double perovskite thin films. The concentration and\ndistribution patterns of ASD are effectively controlled by optimizing growth\nconditions and estimated on both local and global scales utilizing extended\nX-ray absorption fine structure and bulk magnetometry. Depending upon the\ndefect densities, the nature of disorder distribution can vary from homogeneous\nto partially segregated patches. Primarily, the effect of varying B-site\ncationic arrangement in SNMO is reflected as the competition of long range\nferromagnetic (FM) and short scale antiferromagnetic (AFM) interactions\noriginated from ordered Ni-O-Mn and disordered Ni-O-Ni or Mn-O-Mn bonds,\nrespectively, which leads to systematic shift in magnetic transition\ntemperature and drastic drop in saturation magnetization. In addition, we have\nobserved that the gradual increment in density of ASD leads to significant\ndeviation from uniaxial anisotropy character, reduction in anisotropy energy\nand enhancement of moment pinning efficiency. However, the observed signatures\nof $ Ni^{2+}+Mn^{4+} \\longrightarrow Ni^{3+}+Mn^{3+} $ charge\ndisproportionation is found to be independent of cation disorder densities.\nThis work serves as a basic route-map to tune the characteristic magnetic\nanisotropy, magnetic phase transitions, and magnetization reversal mechanism by\ncontrolling ASD in a general double perovskite system.",
        "positive": "Phonon-assisted luminescence in defect centers from many-body\n  perturbation theory: Phonon-assisted luminescence is a key property of defect centers in\nsemiconductors, and can be measured to perform the readout of the information\nstored in a quantum bit, or to detect temperature variations. The investigation\nof phonon-assisted luminescence usually employs phenomenological models, such\nas that of Huang and Rhys, with restrictive assumptions that can fail to be\npredictive. In this work, we predict luminescence and study exciton-phonon\ncouplings within a rigorous many-body perturbation theory framework, an\nanalysis that has never been performed for defect centers. In particular, we\nstudy the optical emission of the negatively-charged boron vacancy in 2D\nhexagonal boron nitride, which currently stands out among defect centers in 2D\nmaterials thanks to its promise for applications in quantum information and\nquantum sensing. We show that phonons are responsible for the observed\nluminescence, which otherwise would be dark due to symmetry. We also show that\nthe symmetry breaking induced by the static Jahn-Teller effect is not able to\ndescribe the presence of the experimentally observed peak at 1.5 eV."
    },
    {
        "anchor": "Thermoelectric transport perpendicular to thin film heterostructures\n  using Monte Carlo technique: The Monte Carlo technique is used to calculate electrical as well as\nthermoelectric transport properties across thin film heterostructures. We study\na thin InGaAsP barrier layer sandwiched between two InGaAs contact layers, when\nthe barrier thickness is in 50nm-2000nm range. We found that with decreasing\nsize, the effective Seebeck coefficient is increased substantially. The\ntransition between pure ballistic thermionic transport and fully diffusive\nthermoelectric transport is also described.",
        "positive": "High power Figure-of-Merit, 10.6-kV AlGaN/GaN lateral Schottky barrier\n  diode with single channel and sub-100-\u03bcm anode-to-cathode spacing: GaN-based lateral Schottky diodes (SBDs) have attracted great attention for\nhigh-power applications due to its combined high electron mobility and large\ncritical breakdown field. However, the breakdown voltage (BV) of the SBDs are\nfar from exploiting the material advantages of GaN at present, limiting the\ndesire to use GaN for ultra-high voltage (UHV) applications. Then, a golden\nquestion is whether the excellent properties of GaN-based materials can be\npractically used in the UHV field? Here we demonstrate UHV AlGaN/GaN SBDs on\nsapphire with a BV of 10.6 kV, a specific on-resistance of 25.8 m{\\Omega}.cm2,\nyielding a power figure of merit of more than 3.8 GW/cm2. These devices are\ndesigned with single channel and 85-{\\mu}m anode-to-cathode spacing, without\nother additional electric field management, demonstrating its great potential\nfor the UHV application in power electronics."
    },
    {
        "anchor": "LanTraP: A code for calculating thermoelectric transport properties with\n  the Landauer formalism: A code for calculating the semi-classical thermoelectric and electronic\ntransport properties is described. It uses the Landauer transport theory, which\nis equivalent to the Boltzmann theory, by introducing a central quantity-the\ndistribution of modes. Its usage enables the so-called band-counting algorithm\nthat can speed up the calculation and offers the potential to rapidly screen\nDFT band structures. Good agreements are found when comparing the results\nobtained using band-counting and established Fourier-based interpolation\nmethods.",
        "positive": "Nucleation instability in super-cooled Cu-Zr-Al glass-forming liquids: Special role in computer simulations of supercooled liquid and glasses is\nplayed by few general models representing certain classes of real glass-forming\nsystems. Recently, it was shown that one of the most widely used model\nglassformers -- Kob-Andersen binary Lennard-Jones mixture -- crystalizes in\nquite lengthy molecular dynamics simulations and, moreover, it is in fact a\nvery poor glassformer at large system sizes. Thus, our understanding of\ncrystallization stability of model glassformers is far from complete due to the\nfact that relatively small system sizes and short timescales have been\nconsidered so far. Here we address this issue for two embedded atom models\nintensively used last years in numerical studies of Cu-Zr-(Al) bulk metallic\nglasses. We consider ${\\rm Cu_{64.5}Zr_{35.5}}$ and ${\\rm\nCu_{46}Zr_{46}Al_{8}}$ alloys as those having high glass-forming ability.\nExploring their structural evolution at continuous cooling and isothermal\nannealing, we observe that both systems nucleate in sufficiently lengthy\nsimulations, though ${\\rm Cu_{46}Zr_{46}Al_{8}}$ demonstrate order of magnitude\nhigher critical nucleation time. Moreover, ${\\rm Cu_{64.5}Zr_{35.5}}$ is\nactually unstable to crystallization for large system sizes ($N > 20,000$).\nBoth systems crystallize with the formation of tetrahedrally close packed Laves\nphases of different types. We reveal that structure of both systems in liquid\nand glassy state contains comparable amount of polytetrahedral clusters. We\nargue that nucleation instability of simulated ${\\rm Cu_{64.5}Zr_{35.5}}$ alloy\nis due to the fact that its composition is very close to that for stable ${\\rm\nCu_2 Zr}$ compound with C15 Laves phase structure."
    },
    {
        "anchor": "Molecular dynamics simulations and photoluminescence measurements of\n  annealed ZnO surfaces: The effect of thermal annealing on wurtzite ZnO, terminated by two surfaces,\n(0 0 0 $\\bar 1$) (which is oxygen-terminated) and (0 0 0 1) (which is\nZn-terminated), is investigated via molecular dynamics simulation using\nreactive force field (ReaxFF). As a result of annealing at a threshold\ntemperature range of 700~K $ < T_{\\mbox{\\small t}} \\leq 800$~K, surface oxygen\natoms begin to sublimate from the (0 0 0 $\\bar 1$) surface, while no atom\nleaves the (0 0 0 1) surface. The ratio of oxygen leaving the surface increases\nwith temperature $T$ (for $T \\geq T_{\\mbox{\\small t}}$). The relative\nluminescence intensity of the secondary peak in the photoluminescence (PL)\nspectra, interpreted as a measurement of amount of vacancies on the sample\nsurfaces, qualitatively agrees with the threshold behavior as found in the MD\nsimulations. Our simulations have also revealed the formation of oxygen dimers\non the surface and evolution of partial charge distribution during the\nannealing process. Our MD simulation based on the ReaxFF is consistent with\nexperimental observations.",
        "positive": "Random close packing fractions of lognormal distributions of hard\n  spheres: We apply a recent one-dimensional algorithm for predicting random close\npacking fractions of polydisperse hard spheres [Farr and Groot, J. Chem. Phys.\n133, 244104 (2009)] to the case of lognormal distributions of sphere sizes and\nmixtures of such populations. We show that the results compare well to two much\nslower algorithms for directly simulating spheres in three dimensions, and show\nthat the algorithm is fast enough to tackle inverse problems in particle\npacking: designing size distributions to meet required criteria. The\none-dimensional method used in this paper is implemented as a computer code in\nthe C programming language, available at\nhttp://sourceforge.net/projects/spherepack1d/ under the terms of the GNU\ngeneral public licence (version 2)."
    },
    {
        "anchor": "Poly(acrylic acid)-coated iron oxide nanoparticles : quantitative\n  evaluation of the coating properties and applications for the removal of a\n  pollutant dye: In this work, 6 to 12 nm iron oxide nanoparticles were synthesized and coated\nwith poly(acrylic acid) chains of molecular weight 2100 g/mol. Based on a\nquantitative evaluation of the dispersions, the bare and coated particles were\nthoroughly characterized. The number densities of polymers adsorbed at the\nparticle surface and of available chargeable groups were found to be 1.9 +/-\n0.3 nm-2 and 26 +/- 4 nm-2, respectively. Occurring via a multi-site binding\nmechanism, the electrostatic coupling leads to a solid and resilient anchoring\nof the chains. To assess the efficacy of the particles for pollutant\nremediation, the adsorption isotherm of methylene blue molecules, a model of\npollutant, was determined. The excellent agreement between the predicted and\nmeasured amounts of adsorbed dyes suggests that most carboxylates participate\nto the complexation and adsorption mechanisms. An adsorption of 830 mg/g was\nobtained. This quantity compares well with the highest values available for\nthis dye.",
        "positive": "Electronic-structural Dynamics in Graphene: We review our recent time- and angle-resolved photoemission spectroscopy\nexperiments, which measure the transient electronic structure of optically\ndriven graphene. For pump photon energies in the near infrared\n($\\hbar\\omega_{\\text{pump}}=950$meV) we have discovered the formation of a\npopulation-inverted state near the Dirac point, which may be of interest for\nthe design of THz lasing devices and optical amplifiers. At lower pump photon\nenergies ($\\hbar\\omega_{\\text{pump}}<400$meV), for which interband absorption\nis not possible in doped samples, we find evidence for free carrier absorption.\nIn addition, when mid-infrared pulses are made resonant with an infrared-active\nin-plane phonon of bilayer graphene ($\\hbar\\omega_{\\text{pump}}=200$meV), a\ntransient enhancement of the electron-phonon coupling constant is observed,\nproviding interesting perspective for experiments that report light-enhanced\nsuperconductivity in doped fullerites in which a similar lattice mode was\nexcited. All the studies reviewed here have important implications for\napplications of graphene in optoelectronic devices and for the dynamical\nengineering of electronic properties with light."
    },
    {
        "anchor": "Fermi Surface and Carriers Compensation of pyrite-type PtBi$_{2}$\n  Revealed by Quantum Oscillations: Large non-saturating magnetoresistance has been observed in various materials\nand electron-hole compensation has been regarded as one of the main mechanisms.\nHere we present a detailed study of the angle-dependent Shubnikov -de Haas\neffect on large magnetoresistance material pyrite-type PtBi$_{2}$, which allows\nus to experimentally reconstruct its Fermi-surface structure and extract the\nphysical properties of each pocket. We find its Fermi surface contains four\ntypes of pockets in the Brillouin zone: three ellipsoid-like hole pockets\n$\\alpha$ with C$_4$ symmetry located on the edges (M points), one intricate\nelectron pocket $\\beta$ merged from four ellipsoids along [111] located on the\ncorners (R points), two smooth and cambered octahedrons $\\gamma$ (electron) and\n$\\delta$ (hole) on the center ($\\Gamma$ point). The deduced carrier densities\nof electrons and holes from the volume of pockets prove carrier compensation.\nThis compensation at low temperatures is also supported by fitting the field\ndependence of Hall and magnetoresistance at different temperatures. We conclude\nthat the compensation is the main mechanism for the large non-saturating\nmagnetoresistance in pyrite-type PtBi$_{2}$. We found the hole pockets {\\alpha}\nmay contribute major mobility because of their light masses and anisotropy to\nrelatively avoid large-angle scattering at low temperature. This may be a\ncommon feature of semimetals with large magnetoresistance. The found\nsub-quadratic magnetoresistance in high field is probably due to\nfield-dependent mobilities, another feature of semimetals under high magnetic\nfields.",
        "positive": "Determining superhydrophobic surfaces from an expanded Cassie Baxter\n  equation describing simple wettability experiments: The characterization of the wetting on superhydrophobic surfaces is rather\ncomplex. Usual contact angle experiments are difficult to perform and the\nlateral movement of droplets as well as the pinning at point defects on the\nsurface can disturb the measurements. Even if precise contact angle\nmeasurements can be performed the information gain is limited if the surface is\nheterogeneously wetted. This results in the possibility of two surfaces with\ndifferent roughness, different surface energy and thus different underlying\nwetting mechanisms exhibiting the same contact angle. We introduce the\nutilization of dynamic wetting experiments as an additional surface probe which\nallows a better characterization of superhydrophobic surfaces. A theoretical\nmodel is presented which describes the spreading of water jets on a\nsuperhydrophobic surface and allows the determination of the wetted fraction of\na heterogeneously wetted superhydrophobic surface. The determined values for\nthe wetted fraction identify a common problem when building artificial super\nhydrophobic surfaces and can fundamentally improve their understanding."
    },
    {
        "anchor": "Ab initio energy landscape of LiF clusters: A global search for possible LiF cluster structures is performed, up to\n(LiF)8. The method is based on simulated annealing, where all the energies are\nevaluated on the ab initio level. In addition, the threshold algorithm is\nemployed to determine the energy barriers for the transitions among these\nstructures, for the cluster (LiF)4, again on the ab initio level; and the\ncorresponding tree graph is obtained.",
        "positive": "Linear scaling computation of the Fock matrix. VIII. Periodic boundaries\n  for exact exchange at the $\u0393$-point: A translationally invariant formulation of the Hartree-Fock (HF)\n$\\Gamma$-point approximation is presented. This formulation is achieved through\nintroduction of the Minimum Image Convention (MIC) at the level of primitive\ntwo-electron integrals, and implemented in a periodic version of the ONX\nalgorithm [J. Chem. Phys, {\\bf 106} 9708 (1997)] for linear scaling computation\nof the exchange matrix. Convergence of the HF-MIC $\\Gamma$-point model to the\nHF ${\\bf k}$-space limit is demonstrated for fully periodic magnesium oxide,\nice and diamond. Computation of the diamond lattice constant using the HF-MIC\nmodel together with the hybrid PBE0 density functional [Theochem, {\\bf 493} 145\n(1999)] yields $a_0=3.569$\\AA with the 6-21G* basis set and a $3\\times3\\times3$\nsupercell. Linear scaling computation of the HF-MIC exchange matrix is\ndemonstrated for diamond and ice in the condensed phase"
    },
    {
        "anchor": "Correlation between transport properties and lattice effects in the\n  NdCoO3 based catalysts and sensor materials: This study presents correlations between the structural and transport\nproperties of pure and doped neodymium cobaltate, a compound of great interest\nfor its foreseen applications as catalyst, sensor and thermoelectric material.\nNeutron and x-ray powder diffraction data have been combined to carefully\ndetermine lattice constants and atomic positions and four probe direct current\nconductivity and thermoelectric power measurements allowed us to follow the\nthermal evolution of the transport properties of these compounds. The dramatic\nimprovement of the room temperature conductivity of Nd0.8Ca0.2CoO3 with respect\nto the pure and the Na-doped compound is explained in terms of a different\nspin-state for the Co ions within this structure. The higher conductivity and\nthe absence of anomalies in the thermal expansion makes the Ca-doped compound\nmore attractive than the pure NdCoO3 in view of possible applications. The\nexperimental data and the Co environment analysis here discussed, in particular\nbond lengths distortion and bending angles, are fully consistent with a spin\nstate (low to intermediate) transition in NdCoO3",
        "positive": "Exciton Binding Energy and Nonhydrogenic Rydberg Series in Monolayer WS2: We have experimentally determined the energies of the ground and first four\nexcited excitonic states of the fundamental optical transition in monolayer\nWS2, a model system for the growing class of atomically thin two-dimensional\nsemiconductor crystals. From the spectra, we establish a large exciton binding\nenergy of 0.32 eV and a pronounced deviation from the usual hydrogenic Rydberg\nseries of energy levels of the excitonic states. We explain both of these\nresults using a microscopic theory in which the non-local nature of the\neffective dielectric screening modifies the functional form of the Coulomb\ninteraction. These strong but unconventional electron-hole interactions are\nexpected to be ubiquitous in atomically thin materials."
    },
    {
        "anchor": "Learning Motifs and their Hierarchies in Atomic Resolution Microscopy: Progress in functional materials discovery has been accelerated by advances\nin high throughput materials synthesis and by the development of\nhigh-throughput computation. However, a complementary robust and high\nthroughput structural characterization framework is still lacking. New methods\nand tools in the field of machine learning suggest that a highly automated\nhigh-throughput structural characterization framework based on atomic-level\nimaging can establish the crucial statistical link between structure and\nmacroscopic properties. Here we develop a machine learning framework towards\nthis goal. Our framework captures local structural features in images with\nZernike polynomials, which is demonstrably noise-robust, flexible, and\naccurate. These features are then classified into readily interpretable\nstructural motifs with a hierarchical active learning scheme powered by a novel\nunsupervised two-stage relaxed clustering scheme. We have successfully\ndemonstrated the accuracy and efficiency of the proposed methodology by mapping\na full spectrum of structural defects, including point defects, line defects,\nand planar defects in scanning transmission electron microscopy (STEM) images\nof various 2D materials, with greatly improved separability over existing\nmethods. Our techniques can be easily and flexibly applied to other types of\nmicroscopy data with complex features, providing a solid foundation for\nautomatic, multiscale feature analysis with high veracity.",
        "positive": "Superconductivity of bulk CaC6: We have obtained bulk samples of the graphite intercalation compound, CaC6,\nby a novel method of synthesis from highly oriented pyrolytic graphite. The\ncrystal structure has been completely determined showing that it is the only\nmember of the MC6, metal-graphite compounds, which has rhombohedral symmetry.\nWe have clearly shown the occurrence of superconductivity in the bulk sample at\n11.5K, using magnetization measurements."
    },
    {
        "anchor": "Dzyaloshinskii-Moryia interaction at an antiferromagnetic interface:\n  first-principles study of FeIr bilayers on Rh(001): We study the magnetic interactions in atomic layers of Fe and 5d\ntransition-metals such as Os, Ir, and Pt on the (001) surface of Rh using\nfirst-principles calculations based on density functional theory. For both\nstackings of the 5d-Fe bilayer on Rh(001) we observe a transition from an\nantiferromagnetic to a ferromagnetic nearest-neighbor exchange interaction upon\n5d band filling. In the sandwich structure 5d/Fe/Rh(001) the nearest neighbor\nexchange is significantly reduced. For FeIr bilayers on Rh(001) we consider\nspin spiral states in order to determine exchange constants beyond nearest\nneighbors. By including spin-orbit coupling we obtain the Dzyaloshinskii-Moriya\ninteraction (DMI). The magnetic interactions in Fe/Ir/Rh(001) are similar to\nthose of Fe/Ir(001) for which an atomic scale spin lattice has been predicted.\nHowever, small deviations between both systems remain due to the different\nlattice constants and the Rh vs. Ir surface layers. This leads to slightly\ndifferent exchange constants and DMI and the easy magnetization direction\nswitches from out-of-plane for Fe/Ir(001) to in-plane for Fe/Ir/Rh(001).\nTherefore a fine tuning of magnetic interactions is possible by using single 5d\ntransition-metal layers which may allow to tailor antiferromagnetic skyrmions\nin this type of ultrathin films. In the sandwich structure Ir/Fe/Rh(001) we\nfind a strong exchange frustration due to strong hybridization of the Fe layer\nwith both Ir and Rh which drastically reduces the nearest-neighbor exchange.\nThe energy contribution from the DMI becomes extremely large and DMI beyond\nnearest neighbors cannot be neglected. We attribute the large DMI to the low\ncoordination of the Ir layer at the surface. We demonstrate that higher- order\nexchange interactions are significant in both systems which may be crucial for\nthe magnetic ground state.",
        "positive": "High diffusivity pathways govern massively enhanced oxidation during\n  tribological sliding: The lifetime of moving metallic components is often limited by accelerated\noxidation. Yet, the mechanisms and pathways for oxidation during tribological\nloading are not well understood. Using copper as a model system,\ntribologically-induced oxidation is systematically investigated by varying the\nsliding speed and test duration under mild tribological loading. We demonstrate\nthat tribo-oxidation is controlled by test duration rather than the number of\ncycles or the sliding speed. Plastic deformation from tribological loading\ncreates dislocations, grain and phase boundaries that act as high diffusivity\npathways. A combination of electron microscopy and atom probe tomography\nrevealed significantly enhanced atomic concentration of the diffusing species\naround dislocations. Oxygen diffusion into the bulk as well as of copper\ntowards the free surface along these defects control the oxide formation\nkinetics. Our work paves the way for formulating a physics-based understanding\nfor tribo-oxidation, which is crucial to develop strategies to prevent\noxidation and to strategically tailor surfaces to increase the lifetime of\nengineering systems."
    },
    {
        "anchor": "Energies of the first row atoms from quantum Monte Carlo: All-electron variational and diffusion quantum Monte Carlo calculations of\nthe ground state energies of the first row atoms (Li to Ne) are reported. We\nuse trial wavefunctions of four types: single determinant Slater-Jastrow\nwavefunctions; multi-determinant Slater-Jastrow wavefunctions; single\ndeterminant Slater-Jastrow wavefunctions with backflow transformations;\nmulti-determinant Slater-Jastrow wavefunctions with backflow transformations.\nAt the diffusion quantum Monte Carlo level and using our best trial\nwavefunctions we recover 99% or more of the correlation energy for Li, Be, B,\nC, N, and Ne, 97% for O, and 98% for F.",
        "positive": "Highly Tunable Magnetic and Magnetotransport Properties of Exchange\n  Coupled Ferromagnet/Antiferromagnet-based Heterostructures: Antiferromagnets (AFMs) with zero net magnetization are proposed as active\nelements in future spintronic devices. Depending on the critical thickness of\nthe AFM thin films and the measurement temperature, bimetallic Mn-based alloys\nand transition metal oxide-based AFMs can host various coexisting ordered,\ndisordered, and frustrated AFM phases. Such coexisting phases in the exchange\ncoupled ferromagnetic (FM)/AFM-based heterostructures can result in unusual\nmagnetic and magnetotransport phenomena. Here, we integrate chemically\ndisordered AFM IrMn3 thin films with coexisting AFM phases into complex\nexchange coupled MgO(001)/Ni3Fe/IrMn3/Ni3Fe/CoO heterostructures and study the\nstructural, magnetic, and magnetotransport properties in various magnetic field\ncooling states. In particular, we unveil the impact of rotating the relative\norientation of the disordered and reversible AFM moments with respect to the\nirreversible AFM moments on the magnetic and magnetoresistance properties of\nthe exchange coupled heterostructures. We further found that the persistence of\nAFM grains with thermally disordered and reversible AFM order is crucial for\nachieving highly tunable magnetic properties and multi-level magnetoresistance\nstates. We anticipate that the introduced approach and the heterostructure\narchitecture can be utilized in future spintronic devices to manipulate the\nthermally disordered and reversible AFM order at the nanoscale."
    },
    {
        "anchor": "Positron studies of surfaces, structure and electronic properties of\n  nanocrystals: A brief review is given of recent positron studies of metal and semiconductor\nnanocrystals. The prospects offered by positron annihilation as a sensitive\nmethod to access nanocrystal (NC) properties are described and compared with\nother experimental methods. The tunability of the electronic structure of\nnanocrystals underlies their great potential for application in many areas.\nOwing to their large surface-to-volume ratio, the surfaces and interfaces of\nNCs play a crucial role in determining their properties. Here we focus on\npositron 2D angular correlation of annihilation radiation (2D-ACAR) and\n(two-detector) Doppler studies for investigating surfaces and electronic\nproperties of CdSe NCs.",
        "positive": "Finite-temperature magnetic properties of Sm2Fe17Nx using an ab-initio\n  effective spin model: In this study, we investigate the finite-temperature magnetic properties of\nSm2Fe17Nx (x = 0,3) using an effective spin model constructed based on the\ninformation obtained by first-principles calculations. We find that assuming\nthe plausible trivalent Sm3+ configuration results in a model that can\nsatisfactorily describe the magnetization curves of Sm2Fe17N3. By contrast, the\nmodel based on the divalent Sm2+ configuration is suitable to reproduce the\nmagnetization curves of Sm2Fe17. These results expand the understanding of how\nelectronic structure affects the magnetic properties of these compounds."
    },
    {
        "anchor": "Doping-induced spin Hall ratio enhancement in A15-phase, Ta-doped Beta-W\n  thin films: As spintronic devices become more and more prevalent, the desire to find Pt\nfree materials with large spin Hall effects is increasing. Previously it was\nshown that Beta W, the metastable A15 structured variant of pure W, has\ncharge-spin conversion efficiencies on par with Pt, and it was predicted that\nBeta W(Ta) alloys should be even more efficient. Here we demonstrate the\nenhancement of the spin Hall ratio (SHR) in A15-phase Beta W films doped with\nTa (W(4-x)Tax where x is between 0.28 and 0.4, deposited at room temperature\nusing DC magnetron co-sputtering. In close agreement with theoretical\npredictions, we find that the SHR of the doped films was approx. 9 percent\nlarger than pure Beta W films. We also found that the SHRs in devices with\nCo2Fe6B2 were nearly twice as large as the SHRs in devices with Co4Fe4B2. This\nwork shows that by optimizing deposition parameters and substrates, the\nfabrication of the optimum W3Ta alloy should be feasible, opening the door to\ncommercially viable, Pt free, spintronic devices.",
        "positive": "Anomalous training effect of perpendicular exchange bias in\n  Pt/Co/Pt/IrMn multilayers: A new characteristic is observed in the training effect of perpendicular\nexchange bias. For Pt/Co/Pt/IrMn multilayers with perpendicular magnetic\nanisotropy, the magnetization reversal process is accompanied by pinned domain\nwall motion and the asymmetry of hysteresis loop is always equal to zero during\nsubsequent measurements. It is interesting to find that the exchange field\ndecreases greatly as a function of the cycling number while the coercivity\nalmost does not change. It is clearly demonstrated that the training effect of\nperpendicular exchange bias strongly depends on the magnetization reversal\nmechanism of the ferromagnetic layer."
    },
    {
        "anchor": "Reply on ``Fluctuation-dissipation considerations for phenomenological\n  damping models for ferromagnetic thin films'' [N. Smith, J. Appl. Phys.\n  \\bf{92}, 3877 (2002)]: We show that the critique of our recent papers presented in the\nabovementioned paper (NS) appeals to an incorrect mathematical analogy between\nelectrical circuits and linear magnetization dynamics, improperly uses\nclassical concepts of normal modes and basic equations, gives inconsistent\nresults and therefore comes to incorrect conclusions.",
        "positive": "High-performance hybrid electronic devices from layered PtSe2 films\n  grown at low temperature: Layered two-dimensional (2D) materials display great potential for a range of\napplications, particularly in electronics. We report the large-scale synthesis\nof thin films of platinum diselenide (PtSe2), a thus far scarcely investigated\ntransition metal dichalcogenide. Importantly, the synthesis by thermal assisted\nconversion is performed at 400 {\\deg}C, representing a breakthrough for the\ndirect integration of this novel material with silicon (Si) technology. Besides\nthe thorough characterization of this new 2D material, we demonstrate its\npromise for applications in high-performance gas sensing with extremely short\nresponse and recovery times observed due to the 2D nature of the films.\nFurthermore, we realized vertically-stacked heterostructures of PtSe2 on Si\nwhich act as both photodiodes and photovoltaic cells. Thus this study\nestablishes PtSe2 as a potential candidate for next-generation sensors and\n(opto-)electronic devices, using fabrication protocols compatible with\nestablished Si technologies."
    },
    {
        "anchor": "Uniform plasma oscillations in ellipsoid of conductive material: The influence of the shape of a sample on the type of uniform dipole\ncollective electrons oscillations is discussed. In samples of a bulk shape\nuniform bulk dipole oscillation (Langmuir oscillation) cannot exist. It exists\nin samples of a thin slab shape only. As uniform bulk dipole oscillations\ncannot penetrate ellipsoidal samples of conductive material, they exist in the\nsurface layer of a sample only (Mie oscillations). Frequencies of Mie\noscillations are alculated for a sample of the shape of an arbitrary ellipsoid.",
        "positive": "Superior Structural, Elastic and Electronic Properties of 2D Titanium\n  Nitride MXenes Over Carbide MXenes: A Comprehensive First Principles Study: The structural, elastic and electronic properties of two-dimensional (2D)\ntitanium carbide/nitride based pristine (Tin+1Cn/Tin+1Nn) and functionalized\nMXenes (Tin+1CnT2/Tin+1NnT2, T stands for the terminal groups: -F, -O and -OH,\nn = 1, 2, 3) are investigated by density functional theory calculations.\nCarbide-based MXenes possess larger lattice constants and monolayer thicknesses\nthan nitride-based MXenes. The in-plane Young's moduli of Tin+1Nn are larger\nthan those of Tin+1Cn, whereas in both systems they decrease with the increase\nof the monolayer thickness. Cohesive energy calculations indicate that MXenes\nwith a larger monolayer thickness have a better structural stability.\nAdsorption energy calculations imply that Tin+1Nn have stronger preference to\nadhere to the terminal groups, which suggests more active surfaces for\nnitride-based MXenes. More importantly, nearly free electron states are\nobserved to exist outside the surfaces of -OH functionalized carbide/nitride\nbased MXenes, especially in Tin+1Nn(OH)2, which provide almost perfect\ntransmission channels without nuclear scattering for electron transport. The\noverall electrical conductivity of nitride-based MXenes is determined to be\nhigher than that of carbide-based MXenes. The exceptional properties of\ntitanium nitride-based MXenes, including strong surface adsorption, high\nelastic constant and Young's modulus, and good metallic conductivity, make them\npromising materials for catalysis and energy storage applications."
    },
    {
        "anchor": "Non-local energetics of random heterogeneous lattices: In this paper, we study the mechanics of statistically non-uniform two-phase\nelastic discrete structures. In particular, following the methodology proposed\nin (Luciano and Willis, Journal of the Mechanics and Physics of Solids 53,\n1505-1522, 2005), energetic bounds and estimates of the Hashin-Shtrikman-Willis\ntype are developed for discrete systems with a heterogeneity distribution\nquantified by second-order spatial statistics. As illustrated by three\nnumerical case studies, the resulting expressions for the ensemble average of\nthe potential energy are fully explicit, computationally feasible and free of\nadjustable parameters. Moreover, the comparison with reference Monte-Carlo\nsimulations confirms a notable improvement in accuracy with respect to\napproaches based solely on the first-order statistics.",
        "positive": "Strength and scales of itinerant spin fluctuations in 3d paramagnetic\n  metals: The full spin density fluctuations (SDF) spectra in 3d paramagnetic metals\nare analyzed from first principles using the linear response technique. Using\nthe calculated complete wavevector and energy dependence of the dynamic spin\nsusceptibility, we obtain the most important, but elusive, characteristic of\nSDF in solids: on-site spin correlator (SC). We demonstrate that the SDF have a\nmixed character consisting of interacting collective and single-particle\nexcitations of similar strength spreading continuously over the entire\nBrillouin zone and a wide energy range up to femtosecond time scales. These\nexcitations cannot be adiabatically separated and their intrinsically\nmultiscale nature should be always taken into account for a proper description\nof metallic systems. Overall, in all studied systems, despite the lack of local\nmoment, we found a very large SC resulting in an effective fluctuating moment\nof the order of several Bohr magnetons."
    },
    {
        "anchor": "Composite nanowires for room-temperature mechanical and electrical\n  bonding: At millimeter dimension or less, the conventional bonding technology in\nelectronic assembly relies heavily on reflow soldering and suffers from severe\nperformance and reliability degradation. Meanwhile, the traditional high\ntemperature bonding process (easily reach 220 oC) tends to result in undesired\nthermal damage and residual stress at the bonding interface. It is therefore a\nmajor challenge to find a means to preparing room-temperature connectors or\nfasteners with good mechanical and electrical bonding. Very recently, composite\nnanowire have been used to fabricate room-temperature fasteners. In this\nchapter, we summarize the state-of-the-art progress on the use of composite\nnanowires for room-temperature mechanical and electrical bonding. Using anodic\naluminum oxide (AAO) and polycarbonate (PC) membrane as template, the\nfabrication of Cu/parylene and Cu/polystyrene nanowires were described.\nMeanwhile, the fabrication of carbon nanotube (CNTs) array was summarized.\nThen, the performances of the composite nanowires (Cu/parylene, Cu/polystyrene\nand CNT-Cu/parylene) used as surface fastener for room-temperature mechanical\nand electrical bonding were demonstrated.",
        "positive": "Transition state dynamics of a driven magnetic free layer: Magnetization switching in ferromagnetic structures is an important process\nfor technical applications such as data storage in spintronics, and therefore\nthe determination of the corresponding switching rates becomes essential. We\ninvestigate a free-layer system in an oscillating external magnetic field\nresulting in an additional torque on the spin. The magnetization dynamics\nincluding inertial damping can be described by the phenomenological Gilbert\nequation. The magnetization switching between the two stable orientations on\nthe sphere then requires the crossing of a potential region characterized by a\nmoving rank-1 saddle. We adopt and apply recent extensions of transition state\ntheory for driven systems to compute both the time-dependent and average\nswitching rates of the activated spin system in the saddle region."
    },
    {
        "anchor": "Remagnetization process of Fe-Rich Amorphous Wire under Time Dependent\n  Tensile Stress: An influence of a time dependent external tensile stress on the\nremagnetization process of a bistable wire is investigated experimentally and\nnumerically. The dependence of the magnetization on the frequency of the\ntensile stress is analyzed in terms of the magnetic domain structure of Fe-rich\nwires. The dependence of the switching field on the phase of the tensile stress\nis presented and reproduced by a straightforward numerical simulation of the\nremagnetization process in a bistable wire. There, the input is the\nexperimental static dependences of the switching field and of the magnetization\nof the wire on an external tensile stress. The presented dependences of the\nswitching field and the magnetization on the periodic tensile stress allow to\ntune the shape of the hysteresis loop, what can be useful in constructing a\nphase sensor.",
        "positive": "Dynamical-charge neutrality at a crystal surface: For both molecules and periodic solids, the ionic dynamical charge tensors\nwhich govern the infrared activity are known to obey a dynamical neutrality\ncondition. This condition enforces their sum to vanish (over the whole finite\nsystem, or over the crystal cell, respectively). We extend this sum rule to the\nnon trivial case of the surface of a semiinfinite solid and show that, in the\ncase of a polar surface of an insulator, the surface ions cannot have the same\ndynamical charges as in the bulk. The sum rule is demonstrated through\ncalculations for the Si-terminated SiC(001) surface."
    },
    {
        "anchor": "Dynamics of Li deposition on epitaxial graphene/Ru(0001) islands: Li metal has been deposited on the surface of a Ru(0001) single crystal\ncontaining patches of monolayer-thick epitaxial graphene islands. The use of\nlow-energy electron microscopy and diffraction allowed us to {\\em in situ}\nmonitor the process by measuring the local work function as well as to study\nthe system in real and reciprocal space, comparing the changes taking place on\nthe graphene with those on the bare Ru(0001) surface. It is found that Li\ndeposition decreases the work function of the graphene islands but to a much\nsmaller degree than of the Ru(0001) surface, as corresponds to its\nintercalation below the graphene overlayer. Finally, the diffusion process of\nLi out of the graphene islands has been monitored by photoelectron microscopy\nusing a visible-light laser.",
        "positive": "Longitudinal acoustic properties of poly(lactic acid) and\n  poly(lactic-co-glycolic acid): Acoustics offers rich possibilities for characterising and monitoring the\nbiopolymer structures being employed in the field of biomedical engineering.\nHere we explore the rudimentary acoustic properties of two common biodegradable\npolymers poly(lactic acid) and poly(lactic-co-glycolic acid). A pulse-echo\ntechnique is developed to reveal the bulk speed of sound, acoustic impedance\nand acoustic attenuation of small samples of the polymer across a pertinent\ntemperature range of 0- 70oC. The glass transition appears markedly as both a\ndiscontinuity in the first derivative of the speed of sound and a sharp\nincrease in the acoustic attenuation. We further extend our analysis to\nconsider the role of ethanol whose presence is observed to dramatically modify\nthe acoustic properties and reduce the glass transition temperature of the\npolymers. Our results highlight the sensitivity of acoustic properties to a\nrange of bulk properties, including visco-elasticity, molecular weight,\nco-polymer ratio, crystallinity and the presence of plasticizers."
    },
    {
        "anchor": "Complex dielectric and impedance behavior of magnetoelectric Fe2TiO5: We have investigated the complex dielectric and impedance properties of\nmagnetoelectric compound Fe2TiO5 (FTO) as a function of temperature (T) and\nfrequency (f) to understand the grain (G) and grain boundary (Gb) contributions\nto its dielectric response. The temperature and frequency dependent dielectric\npermittivity data shows a sharp increase in permittivity above 200K accompanied\nwith a frequency dependent peak in loss. At T less than 175K, only G\ncontribution dominates even at lower frequency (nearly 100Hz), but for T\ngreater than 175K, the Gb contribution starts appearing at low frequency. The\nvalue of critical frequency distinguishing these two contributions increases\nwith increasing temperature. The observed non-Debye dielectric relaxation\nfollows thermally activated process and is attributed to polaron hopping.\nFurther the frequency dependence of ac conductivity follows the Jonscher\npower-law. The temperature dependency of critical exponent s shows that the\ncorrelated barrier hopping model is appropriate to define the conductivity\nmechanism of FTO in the studied temperature regime.",
        "positive": "Two-dimensional van der Waals electrical contact to monolayer\n  MoSi$_2$N$_4$: Two-dimensional (2D) MoSi$_2$N$_4$ monolayer is an emerging class of\nair-stable 2D semiconductor possessing exceptional electrical and mechanical\nproperties. Despite intensive recent research efforts devoted to uncover the\nmaterial properties of MoSi$_2$N$_4$, the physics of electrical contacts to\nMoSi$_2$N$_4$ remains largely unexplored thus far. In this work, we study the\nvan der Waals heterostructures composed of MoSi$_2$N$_4$ contacted by graphene\nand NbS$_2$ monolayers using first-principle density functional theory\ncalculations. We show that the MoSi$_2$N$_4$/NbS$_2$ contact exhibits an\nultralow Schottky barrier height (SBH), which is beneficial for nanoelectronics\napplications. For MoSi$_2$N$_4$/graphene contact, the SBH can be modulated via\ninterlayer distance or via external electric fields, thus opening up an\nopportunity for reconfigurable and tunable nanoelectronic devices. Our findings\nprovide insights on the physics of 2D electrical contact to MoSi$_2$N$_4$, and\nshall offer a critical first step towards the design of high-performance\nelectrical contacts to MoSi$_2$N$_4$-based 2D nanodevices."
    },
    {
        "anchor": "Excitation of vortices using linear and nonlinear magnetostatic waves: It is shown that stationary vortex structures can be excited in a ferrite\nfilm. This is the first proposal for creating vortex structures in the\nimportant cm and mm wavelength ranges. It is shown that both linear and\nnonlinear structures can be excited using a three-beam interaction created with\ncircular antennae. These give rise to a special phase distribution created by\nlinear and nonlinear mixing. An interesting set of three clockwise rotating\nvortices joined by one counter-rotating one presents itself in the linear\nregime: a scenario that is only qualitatively changed by the onset of\nnonlinearity. It is pointed out that control of the vortex structure, through\nparametric coupling, based upon a microwave resonator, is possible and that\nthere are many interesting possibilities for applications.",
        "positive": "Absence of skew scattering in two-dimensional systems: Testing the\n  origins of the anomalous Hall effect: We study the anomalous Hall conductivity in spin-polarized, asymmetrically\nconfined two-dimensional electron and hole systems, focusing on skew-scattering\ncontributions to the transport. We find that the skew scattering, principally\nresponsible for the extrinsic contribution to the anomalous Hall effect,\nvanishes for the two-dimensional electron system if both chiral Rashba subbands\nare partially occupied, and vanishes always for the two-dimensional hole gas\nstudied here, regardless of the band filling. Our prediction can be tested with\nthe proposed coplanar two-dimensional electron/hole gas device and can be used\nas a benchmark to understand the crossover from the intrisic to the extrinsic\nanomalous Hall effect."
    },
    {
        "anchor": "Disproportionation Phenomena on Free and Strained Sn/Ge(111) and\n  Sn/Si(111) Surfaces: Distortions of the $\\sqrt3\\times\\sqrt3$ Sn/Ge(111) and Sn/Si(111) surfaces\nare shown to reflect a disproportionation of an integer pseudocharge, $Q$,\nrelated to the surface band occupancy. A novel understanding of the\n$(3\\times3)$-1U (``1 up, 2 down'') and 2U (``2 up, 1 down'') distortions of\nSn/Ge(111) is obtained by a theoretical study of the phase diagram under\nstrain. Positive strain keeps the unstrained value Q=3 but removes distorsions.\nNegative strain attracts pseudocharge from the valence band causing first a\n$(3\\times3)$-2U distortion (Q=4) on both Sn/Ge and Sn/Si, and eventually a\n$(\\sqrt3\\times\\sqrt3)$-3U (``all up'') state with Q=6. The possibility of a\nfluctuating phase in unstrained Sn/Si(111) is discussed.",
        "positive": "Large Transport Gap Modulation in Graphene via Electric Field Controlled\n  Reversible Hydrogenation: Graphene is of interest in the development of next-generation electronics due\nto its high electron mobility, flexibility and stability. However, graphene\ntransistors have poor on/off current ratios because of the absence of a\nbandgap. One approach to introduce an energy gap is to use hydrogenation\nreaction, which changes graphene into insulating graphane with sp3 bonding.\nHere we show that an electric field can be used to control\nconductor-to-insulator transitions in microscale graphene via a reversible\nelectrochemical hydrogenation in an organic liquid electrolyte containing\ndissociative hydrogen ions. The fully hydrogenated graphene exhibits a lower\nlimit sheet resistance of 200 Gohm/sq, resulting in graphene field-effect\ntransistors with on/off current ratios of 10^8 at room temperature. The devices\nalso exhibit high endurance, with up to one million switching cycles. Similar\ninsulating behaviours are also observed in bilayer graphene, while trilayer\ngraphene remains highly conductive after the hydrogenation. Changes in the\ngraphene lattice, and the transformation from sp2 to sp3 hybridization, is\nconfirmed by in-situ Raman spectroscopy, supported by first-principles\ncalculations."
    },
    {
        "anchor": "A Combined Density Functional Theory and X-ray Photoelectron\n  Spectroscopy Study of the Aromatic Amino Acids: Amino acids are essential to all life. However, our understanding of some\naspects of their intrinsic structure, molecular chemistry, and electronic\nstructure is still limited. In particular the nature of amino acids in their\ncrystalline form, often essential to biological and medical processes, faces a\nlack of knowledge both from experimental and theoretical approaches. An\nimportant experimental technique that has provided a multitude of crucial\ninsights into the chemistry and electronic structure of materials is X-ray\nphotoelectron spectroscopy. Whilst the interpretation of spectra of simple bulk\ninorganic materials is often routine, interpreting core level spectra of\ncomplex molecular systems is complicated to impossible without the help of\ntheory. We have previously demonstrated the ability of density functional\ntheory to calculate binding energies of simple amino acids, using $\\Delta$SCF\nimplemented in a systematic basis set for both gas phase (multiwavelets) and\nsolid state (plane waves) calculations. In this study, we use the same approach\nto successfully predict and rationalise the experimental core level spectra of\nphenylalanine (Phe), tyrosine (Tyr), tryptophan (Trp), and histidine (His) and\ngain an in-depth understanding of their chemistry and electronic structure\nwithin the broader context of more than 20 related molecular systems. The\ninsights gained from this study provide significant information on the nature\nof the aromatic amino acids and their conjugated side chains.",
        "positive": "Crystalline symmetry-protected non-trivial topology in prototype\n  compound BaAl$_4$: The BaAl$_4$ prototype crystal structure is the most populous of all\nstructure types, and is the building block for a diverse set of sub-structures\nincluding the famous ThCr$_2$Si$_2$ family that hosts high-temperature\nsuperconductivity and numerous magnetic and strongly correlated electron\nsystems. The MA$_4$ family of materials (M=Sr, Ba, Eu; A=Al, Ga, In) themselves\npresent an intriguing set of ground states including charge and spin orders,\nbut have largely been considered as uninteresting metals. Using electronic\nstructure calculations, symmetry analysis and topological quantum chemistry\ntechniques, we predict the exemplary compound BaAl$_4$ to harbor a\nthree-dimensional Dirac spectrum with non-trivial topology and possible nodal\nlines crossing the Brillouin zone, wherein one pair of semi-Dirac points with\nlinear dispersion along the $k_z$ direction and quadratic dispersion along the\n$k_x/k_y$ direction resides on the rotational axis with $C_{4v}$ point group\nsymmetry. Electrical transport measurements reveal the presence of an extremely\nlarge, unsaturating positive magnetoresistance in BaAl$_4$ despite an\nuncompensated band structure, and quantum oscillations and angle-resolved\nphotoemission spectroscopy measurements confirm the predicted multiband\nsemimetal structure with pockets of Dirac holes and a Van Hove singularity\n(VHS) remarkably consistent with the theoretical prediction. We thus present\nBaAl$_4$ as a new topological semimetal, casting its prototype status into a\nnew role as building block for a vast array of new topological materials."
    },
    {
        "anchor": "Achieving High Curie Temperature in (Ga,Mn)As: We study the effects of growth temperature, Ga:As ratio and post-growth\nannealing procedure on the Curie temperature, Tc, of (Ga,Mn)As layers grown by\nmolecular beam epitaxy. We achieve the highest Tc values for growth\ntemperatures very close to the 2D-3D phase boundary. The increase in Tc, due to\nthe removal of interstitial Mn by post growth annealing, is counteracted by a\nsecond process which reduces Tc and which is more effective at higher annealing\ntemperatures. Our results show that it is necessary to optimize the growth\nparameters and post growth annealing procedure to obtain the highest Tc.",
        "positive": "Dirac states with knobs on: interplay of external parameters and the\n  surface electronic properties of 3D topological insulators: Topological insulators are a novel materials platform with high applications\npotential in fields ranging from spintronics to quantum computation. In the\nongoing scientific effort to demonstrate controlled manipulation of their\nelectronic structure by external means, stoichiometric variation and surface\ndecoration are two effective approaches that have been followed. In ARPES\nexperiments, both approaches are seen to lead to electronic band structure\nchanges. Such approaches result in variations of the energy position of bulk\nand surface-related features and the creation of two-dimensional electron\ngases.The data presented here demonstrate that a third manipulation handle is\naccessible by utilizing the amount of illumination a topological insulator\nsurface has been exposed to under typical experimental ARPES conditions. Our\nresults show that this new, third, knob acts on an equal footing with\nstoichiometry and surface decoration as a modifier of the electronic band\nstructure, and that it is in continuous competition with the latter. The data\nclearly point towards surface photovoltage and photo-induced desorption as the\nphysical phenomena behind modifications of the electronic band structure under\nexposure to high-flux photons. We show that the interplay of these phenomena\ncan minimize and even eliminate the adsorbate-related surface band bending on\ntypical binary, ternary and quaternary Bi-based topological insulators.\nIncluding the influence of the sample temperature, these data set up a\nframework for the external control of the electronic band structure in\ntopological insulator compounds in an ARPES setting. Four external knobs are\navailable: bulk stoichiometry, surface decoration, temperature and photon\nexposure. These knobs can be used in conjunction to tune the band energies near\nthe surface and consequently influence the topological properties of the\nrelevant electronic states."
    },
    {
        "anchor": "Exciton states in monolayer MoSe2: impact on interband transitions: We combine linear and non-linear optical spectroscopy at 4K with ab initio\ncalculations to study the electronic bandstructure of MoSe2 monolayers. In\n1-photon photoluminescence excitation (PLE) and reflectivity we measure a\nseparation between the A- and B-exciton emission of 220 meV. In 2-photon PLE we\ndetect for the A- and B-exciton the 2p state 180meV above the respective 1s\nstate. In second harmonic generation (SHG) spectroscopy we record an\nenhancement by more than 2 orders of magnitude of the SHG signal at resonances\nof the charged exciton and the 1s and 2p neutral A- and B-exciton. Our\npost-Density Functional Theory calculations show in the conduction band along\nthe $K-\\Gamma$ direction a local minimum that is energetically and in k-space\nclose to the global minimum at the K-point. This has a potentially strong\nimpact on the polarization and energy of the excitonic states that govern the\ninterband transitions and marks an important difference to MoS2 and WSe2\nmonolayers.",
        "positive": "Transport anomaly in the low energy regime of spin chains: The anomalous thermal conductivity in spin chains observed in experiments is\nstudied for the low temperature regime. In the effective dynamics with most\nrealistic perturbations, the so-called Umklapp terms is irrelevant to reduce\nmean free path in the energy transport at even finite temperatures. This is\nconsistent with large conductivities found in recent experiments. The Drude\nweight which is the prefactor in the divergent conductivity is calculated, and\nthe temperature dependence is discussed."
    },
    {
        "anchor": "Atomic structure of silver chloride formed on Ag(111) surface upon low\n  temperature chlorination: The structure of AgCl formed in the course of chlorine adsorption on Ag(111)\nsurface was studied by STM. For the first time atomic resolution STM images of\nsilver chloride were obtained. The silver chloride was detected as small (30-60\nA in diameter) islands located on the atomic terraces. The upper plane of the\nislands was found to be AgCl(111) with interatomic distance close to the bulk\nvalue. The chloride surface lattice was not rotated with respect to the\nsubstrate. A possible mechanism of AgCl growth on Ag(111) is discussed.",
        "positive": "Order and randomness in dopant distributions: exploring the\n  thermodynamics of solid solutions from atomically resolved imaging: Exploration of structure-property relationships as a function of dopant\nconcentration is commonly based on mean field theories for solid solutions.\nHowever, such theories that work well for semiconductors tend to fail in\nmaterials with strong correlations, either in electronic behavior or chemical\nsegregation. In these cases, the details of atomic arrangements are generally\nnot explored and analyzed. The knowledge of the generative physics and\nchemistry of the material can obviate this problem, since defect configuration\nlibraries as stochastic representation of atomic level structures can be\ngenerated, or parameters of mesoscopic thermodynamic models can be derived. To\nobtain such information for improved predictions, we use data from atomically\nresolved microscopic images that visualize complex structural correlations\nwithin the system and translate them into statistical mechanical models of\nstructure formation. Given the significant uncertainties about the microscopic\naspects of the material's processing history along with the limited number of\navailable images, we combine model optimization techniques with the principles\nof statistical hypothesis testing. We demonstrate the approach on data from a\nseries of atomically-resolved scanning transmission electron microscopy images\nof Mo$_x$Re$_{1-x}$S$_2$ at varying ratios of Mo/Re stoichiometries, for which\nwe propose an effective interaction model that is then used to generate atomic\nconfigurations and make testable predictions at a range of concentrations and\nformation temperatures."
    },
    {
        "anchor": "van der Waals dispersion power laws for cleavage, exfoliation and\n  stretching in multi-scale, layered systems: Layered and nanotubular systems that are metallic or graphitic are known to\nexhibit unusual dispersive van der Waals (vdW) power laws under some\ncircumstances. In this letter we investigate the vdW power laws of bulk and\nfinite layered systems and their interactions with other layered systems and\natoms in the electromagnetically non-retarded case. The investigation reveals\nsubstantial difference between `cleavage' and `exfoliation' of graphite and\nmetals where cleavage obeys a $C_2 D^{-2}$ vdW power law while exfoliation\nobeys a $C_3 \\log(D/D_0) D^{-3}$ law for graphitics and a $C_{5/2} D^{-5/2}$\nlaw for layered metals. This leads to questions of relevance in the\ninterpretation of experimental results for these systems which have previously\nassumed more trival differences. Furthermore we gather further insight into the\neffect of scale on the vdW power laws of systems that simultaneously exhibit\nmacroscopic and nanoscopic dimensions. We show that, for metallic and graphitic\nlayered systems, the known \"unusual\" power laws can be reduced to standard or\nnear standard power laws when the effective scale of one or more dimension is\nchanged. This allows better identification of the systems for which the\ncommonly employed `sum of $C_6 D^{-6}$' type vdW methods might be valid such as\nlayered bulk to layered bulk and layered bulk to atom.",
        "positive": "X-Ray Standing Waves at the Total Reflection Condition: Direct Method\n  and Coherence Effects: Fresnel theory is used to derive the complex electric-fields above and below\nan X-ray reflecting interface that separates two materials with differing\nindices of refraction. The interference between the incident and reflected\nwaves produces an X-ray standing wave (XSW) above the reflecting interface. The\nXSW intensity modulation is strongly enhanced by the total external reflection\n(TR) condition, which occurs at incident angles less than the critical angle.\nAt these small milliradian incident angles the XSW period (lambda/2theta)\nbecomes very large, which makes the TR-XSW an ideal probe for studying\nlow-density structures that extend 1 to 1000 nm above the reflecting interface.\nFourier inversion of the XSW induced modulation in the X-ray fluorescence (XRF)\nyield from a specific atomic distribution within the overlayer directly\nproduces a model-independent 1-D atomic density profile. The modulation can\nalso be used to analyze the degree of coherence in the incident X-ray beam."
    },
    {
        "anchor": "Elastocaloric Effect in Graphene Kirigami: Kirigami, a traditional Japanese art of paper-cutting, has recently been\nexplored for its elastocaloric effect (ECE) in kirigami-based materials (KMs),\nwhere applying strain induces temperature changes. In this study, we\ninvestigate the ECE in a nanoscale graphene kirigami (GK) monolayer,\nrepresenting the thinnest possible KM, to better understand this phenomenon.\nThrough molecular dynamics simulations, we analyze the temperature change and\ncoefficient of performance (COP) of the nanoscale GK architecture. Our findings\nreveal that while GKs lack the intricate temperature changes observed in\nmacroscopic KMs, they exhibit a substantial temperature change of approximately\n9.32 K (23 times higher than that of macroscopic KMs, which is about 0.4K) for\nheating and -3.50 K for cooling. Additionally, they demonstrate reasonable COP\nvalues of approximately 1.57 and 0.62, respectively. It is noteworthy that the\none-atom-thick graphene configuration prevents the occurrence of the complex\ntemperature distribution observed in macroscopic KMs.",
        "positive": "Long-range electrostatic contribution to the electron-phonon couplings\n  and mobilities of two-dimensional and bulk materials: Charge transport plays a crucial role in manifold potential applications of\ntwo-dimensional materials, including field effect transistors, solar cells, and\ntransparent conductors. At most operating temperatures, charge transport is\nhindered by scattering of carriers by lattice vibrations. Assessing the\nintrinsic phonon-limited carrier mobility is thus of paramount importance to\nidentify promising candidates for next-generation devices. Here we provide a\nframework to efficiently compute the drift and Hall carrier mobility of\ntwo-dimensional materials through the Boltzmann transport equation by relying\non a Fourier-Wannier interpolation. Building on a recent formulation of\nlong-range contributions to dynamical matrices and phonon dispersions [Phys.\nRev. X 11, 041027 (2021)], we extend the approach to electron-phonon coupling\nincluding the effect of dynamical dipoles and quadrupoles. We identify an\nunprecedented contribution associated with the Berry connection that is crucial\nto preserve the Wannier-gauge covariance of the theory. This contribution is\nnot specific to 2D crystals, but also concerns the 3D case, as we demonstrate\nvia an application to bulk SrO. We showcase our method on a wide selection of\nrelevant monolayers ranging from SnS2 to MoS2, graphene, BN, InSe, and\nphosphorene. We also discover a non-trivial temperature evolution of the Hall\nhole mobility in InSe whereby the mobility increases with temperature above 150\nK due to the mexican-hat electronic structure of the InSe valence bands.\nOverall, we find that dynamical quadrupoles are essential and can impact the\ncarrier mobility in excess of 75%."
    },
    {
        "anchor": "Improved Calculation of Vibrational Mode Lifetimes in Anharmonic Solids\n  - Part I: Theory: We propose here a formal foundation for practical calculations of vibrational\nmode lifetimes in solids. The approach is based on a recursion method analysis\nof the Liouvillian. From this we derive the lifetime of a vibrational mode in\nterms of moments of the power spectrum of the Liouvillian as projected onto the\nrelevant subspace of phase space. In practical terms, the moments are evaluated\nas ensemble averages of well-defined operators, meaning that the entire\ncalculation is to be done with Monte Carlo. These insights should lead to\nsignificantly shorter calculations compared to current methods. A companion\npiece presents numerical results.",
        "positive": "Carbon and vacancy centers in hexagonal boron nitride: Creation of defect with predetermined optical, chemical and other\ncharacteristics is a powerful tool to enhance the functionalities of materials.\nHerewith, we utilize density functional theory to understand the microscopic\nmechanisms of formation of defects in hexagonal boron nitride based on\nvacancies and substitutional atoms. Through in-depth analysis of the\ndefect-induced band structure and formation energy in varying growth\nconditions, we uncovered a dominant role of interdefect electron paring in\nstabilization of defect complexes. The electron reorganization modifies the\nexchange component of the electronic interactions which dominates over direct\nCoulomb repulsion or structural relaxation effects making the combination of\nacceptor- and donor-type defect centers energetically favorable. Based on an\nanalysis of a large number of defect complexes we develop a simple picture of\nthe inheritance of electronic properties when individual defects are combined\ntogether to form more complex centers."
    },
    {
        "anchor": "Search for Origin of Room Temperature Ferromagnetism Properties in Ni\n  doped ZnO Nanostructure: The origin of room temperature (RT) ferromagnetism (FM) in Ni doped ZnO\nsamples are systematically investigated through physical, optical, and magnetic\nproperties of nanostructure, prepared by simple low-temperature wet chemical\nmethod. Reitveld refinement of X-ray diffraction pattern displays an increase\nin lattice parameters with strain relaxation and contraction in Zn/O occupancy\nratio by means of Ni-doping. Similarly scanning electron microscope\ndemonstrates modification in the morphology from nanorods to nanoflakes with Ni\ndoping, suggests incorporation of Ni ions in ZnO. More interestingly, XANES\n(X-ray absorption near edge spectroscopy) measurements confirm that Ni is being\nincorporated in ZnO as Ni2+. EXAFS (Extended X-ray Absorption Fine Structure)\nanalysis reveals that structural disorders near the Zn sites in the ZnO samples\nupsurges with increasing Ni concentration. Raman spectroscopy exhibits\nadditional defect driven vibrational mode at 275 cm-1, appeared with Ni-doped\nsample only and the shift with broadening in 580 cm-1 peak, which manifests the\npresence of the oxygen vacancy (VO) related defects. Moreover, in\nphotoluminescence (PL) spectra we observed peak appears at 524 nm, indicates\nthe presence of singly ionized VO+, which may activate bound magnetic polarons\n(BMPs) in dilute magnetic semiconductors (DMSs). Magnetization measurements\nindicate weak ferromagnetism at RT, which rises with increasing Ni\nconsolidation. It is therefore proposed that effect of the Ni-ions as well as\nthe inherent exchange interactions rising from VO+ assist to produce BMPs,\nwhich are accountable for the RT-FM in Zn1-xNixO (0<x<0.125) system.",
        "positive": "Deep Levels and Mixed Conductivity in Organometallic Halide Perovskites: Understanding the type, formation energy and capture cross section of defects\nis one of the challenges in the field of organometallic halide perovskite\n(OMHP) devices. Currently, such understanding is limited, restricting the power\nconversion efficiencies of OMHPs solar cells from reaching their Shockley\nQueisser limit. Here, we report on deep level (DL) defects and their effect on\nfree charge transport properties of single crystalline methylammonium lead\nbromide perovskite (MAPB). In order to determine DL activation energy and\ncapture cross section we used photo-Hall effect spectroscopy (PHES) with\nenhanced illumination in both steady-state and dynamic regimes. This method has\nshown to be convenient due to the direct DL visualization by sub-bandgap\nphoto-excitation of trapped carriers. DLs with activation energies of 1.05 eV,\n1.5 eV, and 1.9 eV above valence band were detected. The hole capture cross\nsection was found using photoconductivity relaxation after sub-bandgap\nphoto-excitation. We found the DL defects responsible for non-radiative\nrecombination and its impact on band alignment for the first time.\nAdditionally, the transport properties of MAPB single crystal is measured by\nTime of Flight (ToF) at several biases. The analysis of ToF measurement further\nconfirms increase of Hall mobility and the enhancement of hole transport\nproduced by sub-bandgap illumination in MAPB devices. Our studies provide a\nstrong evidence on deep levels in OMHPs and opens a richer picture of the role\nand properties of deep levels in MAPB single crystals as a system model for the\nfirst time. The deeper knowledge of the electrical structure of OMHP could open\nfurther opportunities in the development of more feasible technology."
    },
    {
        "anchor": "Effect of doping, photodoping and bandgap variation on the performance\n  of perovskite solar cells: Most traditional semiconductor materials are based on the control of doping\ndensities to create junctions and thereby functional and efficient electronic\nand optoelectronic devices. The technology development for halide perovskites\nhad initially only rarely made use of the concept of electronic doping of the\nperovskite layer and instead employed a variety of different contact materials\nto create functionality. Only recently, intentional, or unintentional doping of\nthe perovskite layer is more frequently invoked as an important factor\nexplaining differences in photovoltaic or optoelectronic performance in certain\ndevices. Here we use numerical simulations to study the influence of doping and\nphotodoping on photoluminescence quantum yield as well as other device relevant\nmetrics. We find that doping can improve the photoluminescence quantum yield by\nmaking radiative recombination faster. This effect can benefit or harm\nphotovoltaic performance given that the improvement of photoluminescence\nquantum efficiency and open-circuit voltage is accompanied by a reduction of\nthe diffusion length. This reduction will eventually lead to inefficient\ncarrier collection at high doping densities. The photovoltaic performance might\nimprove at an optimum doping density which depends on a range of factors such\nas the mobilities of the different layers and the ratio of the capture cross\nsections for electrons and holes.",
        "positive": "The Emergence of Unconventional Plasmons Driven by Correlated Electron\n  Interaction in B-site of 2D Hybrid Organic-Inorganic Perovskites: Hybrid organic-inorganic perovskites (HOIPs) have emerged to the forefront of\noptoelectronic materials advancement in the past few years. Due to the nature\nof organic compounds within the perovskite structure, its optoelectronic\nproperties are affected by complex interaction and correlation effects between\nthe organic and inorganic ions. Using spectroscopic ellipsometry, we observe\ntwo broad plasmonic excitation from the calculated loss function (LF)\n-Im[\\varepislon^{-1} (\\omega)], peak A' and B' at 3.28 eV and 4.26 eV,\nrespectively.The presence of these two asymmetric peaks in the spectroscopic\nellipsometry (SE) spectra indicates the existence of unconventional plasmons at\nroom temperature. This is inferred due to the absence of the zero-crossing in\nthe real part of dielectric function \\varepsilon_1 (\\omega). Through combined\nNear-Edge X-ray Absorption Fine Structure (NEXAFS) and Resonant Photoemission\nSpectroscopies (ResPES), we observe resonance enhancement peak close to 15 eV\nin the C K-edge region that unravels a charge transfer event due to the opening\nof an extra autoionization channel. Additionally, photoluminescence (PL)\nspectrum confirms the presence of broadband emission originating from the\nself-trapped emission excitons at 2.38 eV due to the soft 2D-HOIPs crystal\nstructure. We believe that these phenomena directly impact the correlation\nstrength in 2D-HOIPs. Our results have confirmed the existence of\nunconventional plasmons of 2D-HOIPs at room temperature. Such studies in the\nemission and plasmonic behavior of perovskites will pave the way for the\nefficient light emitting devices or lasers with minimal integrations of the\nmaterials."
    },
    {
        "anchor": "Phase boundary anisotropy and its effects on the maze-to-lamellar\n  transition in a directionally solidified Al-Al2Cu eutectic: Solid-solid phase boundary anisotropy is a key factor controlling the\nselection and evolution of non-faceted eutectic patterns during directional\nsolidification. This is most remarkably observed during the so-called\nmaze-to-lamellar transition. By using serial sectioning, we followed the\nspatio-temporal evolution of a maze pattern over long times in a large Al-Al2Cu\neutectic grain with known crystal orientation of the Al and Al2Cu phases, hence\nknown crystal orientation relationship (OR). The corresponding phase boundary\nenergy anisotropy ($\\gamma$-plot) was also known, as being previously estimated\nfrom molecular-dynamics computations. The experimental observations reveal the\ntime-scale of the maze-to-lamellar transition and shed light on the processes\ninvolved in the gradual alignment of the phase boundaries to one distinct\nenergy minimum which nearly corresponds to one distinct plane from the family\n$\\{120\\}^{\\rm{Al}} //\\{110\\}^{\\rm{Al2Cu}}$. This particular plane is selected\ndue to a crystallographic bias induced by a small disorientation of the\ncrystals relative to the perfect OR. The symmetry of the OR is thus slightly\nbroken, which promotes lamellar alignment. Finally, the maze-to-lamellar\ntransition leaves behind a network of fault lines inherited from the phase\nboundary alignment process. In the maze pattern, the fault lines align along\nthe corners of the Wulff shape, thus allowing us to propose a link between the\npattern defects and missing orientations in the Wulff shape",
        "positive": "A Discrete-to-Continuum Model of Weakly Interacting Incommensurate\n  Chains: In this paper we use a formal discrete-to-continuum procedure to derive a\ncontinuum variational model for two chains of atoms with slightly\nincommensurate lattices. The chains represent a cross-section of a\nthree-dimensional system consisting of a graphene sheet suspended over a\nsubstrate. The continuum model recovers both qualitatively and quantitatively\nthe behavior observed in the corresponding discrete model. The numerical\nsolutions for both models demonstrate the presence of large commensurate\nregions separated by localized incommensurate domain walls."
    },
    {
        "anchor": "Extreme Metastability of Diamond and its Transformation to BC8\n  Post-Diamond Phase of Carbon: Diamond possesses exceptional physical properties due to its remarkably\nstrong carbon-carbon bonding, leading to significant resilience to structural\ntransformations at very high pressures and temperatures. Despite several\nexperimental attempts, synthesis and recovery of the theoretically predicted\npost-diamond BC8 phase remains elusive. Through quantum accurate, multi-million\natom molecular dynamics (MD) simulations, we have uncovered the extreme\nmetastability of diamond at very high pressures, significantly exceeding its\nrange of thermodynamic stability. We predict the post-diamond BC8 phase to be\nexperimentally accessible only within a narrow high pressure-temperature region\nof the carbon phase diagram. The diamond to BC8 transformation proceeds through\npre-melting followed by BC8 nucleation and growth in the metastable carbon\nliquid. We propose a double-shock compression pathway to achieve BC8 synthesis,\nwhich is currently being explored in theory-inspired experiments at the\nNational Ignition Facility.",
        "positive": "Layer shift factor in layered hybrid perovskites -- univocal\n  quantitative descriptor of composition-structure-property relationships: Asceding interest of the scientific community in layered hybrid halide\nperovskites (LHHPs) as materials for innovative photovoltaic and optoelectronic\napplications led to unprecedented expansion of this family of compounds,\nreaching now several hundred refined structures. Despite the unique structural\ndiversity of LHHPs, traditional approaches of describing their structures, such\nas dividing into Dion-Jacobson (DJ) or Ruddlesden-Popper (RP) phases for mostt\nstructures are ambiguous and unquantifiable. Here, we introduced a quantitative\nlayer shift factor (LSF) for a univocal classification and quantitative\ncomparison of the structures. We also developed an algorithm for automatic\ncalculation of the LSF for such structures. We demonstrate the application of\nthe proposed approach for an analysis of correlations between LSF and band gap\nto reveal \"structure-property\" relationships. Our study gives a simple and\nuseful approach to classify of either the layered perovskite-like structures or\nother layered compounds composed of layers of vertex-connected octahedra as a\nstructural unit."
    },
    {
        "anchor": "Quasichemical Models of Multicomponent Nonlinear Diffusion: Diffusion preserves the positivity of concentrations, therefore,\nmulticomponent diffusion should be nonlinear if there exist non-diagonal terms.\nThe vast variety of nonlinear multicomponent diffusion equations should be\nordered and special tools are needed to provide the systematic construction of\nthe nonlinear diffusion equations for multicomponent mixtures with significant\ninteraction between components. We develop an approach to nonlinear\nmulticomponent diffusion based on the idea of the reaction mechanism borrowed\nfrom chemical kinetics.\n  Chemical kinetics gave rise to very seminal tools for the modeling of\nprocesses. This is the stoichiometric algebra supplemented by the simple\nkinetic law. The results of this invention are now applied in many areas of\nscience, from particle physics to sociology. In our work we extend the area of\napplications onto nonlinear multicomponent diffusion.\n  We demonstrate, how the mechanism based approach to multicomponent diffusion\ncan be included into the general thermodynamic framework, and prove the\ncorresponding dissipation inequalities. To satisfy thermodynamic restrictions,\nthe kinetic law of an elementary process cannot have an arbitrary form. For the\ngeneral kinetic law (the generalized Mass Action Law), additional conditions\nare proved. The cell--jump formalism gives an intuitively clear representation\nof the elementary transport processes and, at the same time, produces kinetic\nfinite elements, a tool for numerical simulation.",
        "positive": "2D-MoS2 with Narrowest Excitonic Linewidths Grown by Flow-Less Direct\n  Heating of Bulk Powders: Developing techniques for high-quality synthesis of mono and few-layered 2D\nmaterials with lowered complexity and cost continues to remain an important\ngoal, both for accelerating fundamental research and for applications\ndevelopment. We present the simplest conceivable technique to synthesize\nmicrometer-scale single-crystal triangular monolayers of MoS2, i.e. by direct\nheating of bulk MoS2 powder onto proximally-placed substrates. Room-temperature\nexcitonic linewidth values of our samples are narrower and more uniform than\nthose of 2D-MoS2 obtained by most other techniques reported in literature, and\ncomparable to those of ultraflat h-BN-capped mechanically exfoliated samples,\nindicative of their high quality. Feature-rich Raman spectra absent in samples\ngrown or obtained by most other techniques, also stand out as a testament of\nthe high quality of our samples. A contact-growth mode facilitates direct\ngrowth of crystallographically-strained circular samples, which allows us to\ndirectly compare the optoelectronic properties of flat vs. strained growth from\nthe same growth runs. Our method allows, for the first time, to quantitatively\ncompare the impact of strain on excitonic and Raman peak positions on\nidentically-synthesized 2D-MoS2. Strain leads to average Red-shifts of ~ 30 meV\nin the A-exciton position, and ~ 2 cm-1 in the E12g Raman peak in these\nsamples. Our findings open-up several new possibilities that expand 2D material\nresearch. By eliminating the need for carrier gas flow, mechanical motion or\nchemical reactions, our method can be either miniaturized for substantially\nlow-cost, high-quality scientific research or potentially scaled-up for\nmass-production of 2D crystals for commercial purposes. Moreover, we believe\nthis technique can also be extended to other transition metal dichalcogenides\nand other layered materials."
    },
    {
        "anchor": "Physical descriptor for the Gibbs energy of inorganic crystalline solids\n  and temperature-dependent materials chemistry: The Gibbs energy, G, determines the equilibrium conditions of chemical\nreactions and materials stability. Despite this fundamental and ubiquitous\nrole, G has been tabulated for only a small fraction of known inorganic\ncompounds, impeding a comprehensive perspective on the effects of temperature\nand composition on materials stability and synthesizability. Here, we use the\nSISSO (sure independence screening and sparsifying operator) approach to\nidentify a simple and accurate descriptor to predict G for stoichiometric\ninorganic compounds with ~50 meV/atom (~1 kcal/mol) resolution, and with\nminimal computational cost, for temperatures ranging from 300-1800 K. We then\napply this descriptor to ~30,000 known materials curated from the Inorganic\nCrystal Structure Database (ICSD). Using the resulting predicted thermochemical\ndata, we generate thousands of temperature-dependent phase diagrams to provide\ninsights into the effects of temperature and composition on materials\nsynthesizability and stability and to establish the temperature-dependent scale\nof metastability for inorganic compounds.",
        "positive": "Dielectric study of the glass transition: correlation with calorimetric\n  data: The glass transition in amorphous poly(ethylene terephthalate) is studied by\nthermally stimulated depolarization currents (TSDC) and differential scanning\ncalorimetry (DSC). The ability of TSDC to decompose a distributed relaxation,\nas the glass transition, into its elementary components is demonstrated. Two\npolarization techniques, windows polarization (WP) and non-isothermal windows\npolarization (NIW), are employed to assess the influence of thermal history in\nthe results. The Tool-Narayanaswami-Moynihan (TNM) model has been used to fit\nthe TSDC spectra. The most important contributions to the relaxation comes from\nmodes with non-linearity (x) around 0.7. Activation energies yield by this\nmodel are located around 1eV for polarization temperature (Tp) below 50C and\nthey raise up to values higher than 8eV as Tp increases (up to 80C). There are\nfew differences between results obtained with WP and NIW but, nonetheless,\nthese are discussed. The obtained kinetic parameters are tested against DSC\nresults in several conditions. Calculated DSC curves at several cooling and\nheating rates can reproduce qualitatively experimental DSC results. These\nresults also demonstrate that modelization of the non-equilibrium kinetics\ninvolved in TSDC spectroscopy is a useful experimental tool for glass\ntransition studies in polar polymers."
    },
    {
        "anchor": "The many-body exchange-correlation hole at metal surfaces: We present a detailed study of the coupling-constant-averaged\nexchange-correlation hole density at a jellium surface, which we obtain in the\nrandom-phase approximation (RPA) of many-body theory. We report contour plots\nof the exchange-only and exchange-correlation hole densities, the integration\nof the exchange-correlation hole density over the surface plane, the on-top\ncorrelation hole, and the energy density. We find that the on-top correlation\nhole is accurately described by local and semilocal density-functional\napproximations. We also find that for electrons that are localized far outside\nthe surface the main part of the corresponding exchange-correlation hole is\nlocalized at the image plane.",
        "positive": "Possible spin gapless semiconductor type behaviour in CoFeMnSi epitaxial\n  thin films: Spin-gapless semiconductors with their unique band structures have recently\nattracted much attention due to their interesting transport properties that can\nbe utilized in spintronics applications. We have successfully deposited the\nthin films of quaternary spin-gapless semiconductor CoFeMnSi Heusler alloy on\nMgO (001) substrates using a pulsed laser deposition system. These films show\nepitaxial growth along (001) direction and display uniform and smooth\ncrystalline surface. The magnetic properties reveal that the film is\nferromagnetically soft along the in-plane direction and its Curie temperature\nis well above 400 K. The electrical conductivity of the film is low and\nexhibits a nearly temperature independent semiconducting behaviour. The\nestimated temperature coefficient of resistivity for the film is -7x10^-10\nOhm.m/K, which is comparable to the values reported for spin-gapless\nsemiconductors."
    },
    {
        "anchor": "High-frequency performance of scaled carbon nanotube array field-effect\n  transistors: We report the radio-frequency performance of carbon nanotube array\ntransistors that have been realized through the aligned assembly of highly\nseparated, semiconducting carbon nanotubes on a fully scalable device platform.\nAt a gate length of 100 nm, we observe output current saturation and obtain\nas-measured, extrinsic current gain and power gain cut-off frequencies,\nrespectively, of 7 GHz and 15 GHz. While the extrinsic current gain is\ncomparable to the state-of-the-art the extrinsic power gain is improved. The\nde-embedded, intrinsic current gain and power gain cut-off frequencies of 153\nGHz and 30 GHz are the highest values experimentally achieved to date. We\nanalyze the consistency of DC and AC performance parameters and discuss the\nrequirements for future applications of carbon nanotube array transistors in\nhigh-frequency electronics.",
        "positive": "Calculations of spin-disorder resistivity from first principles: Spin-disorder resistivity of Fe and Ni is studied using the noncollinear\ndensity functional theory. The Landauer conductance is averaged over random\ndisorder configurations and fitted to Ohm's law. The distribution function is\napproximated by the mean-field theory. The dependence of spin-disorder\nresistivity on magnetization in Fe is found to be in excellent agreement with\nthe results for the isotropic s-d model. In the fully disordered state,\nspin-disorder resistivity for Fe is close to experiment, while for fcc Ni it\nexceeds the experimental value by a factor of 2.3. This result indicates strong\nmagnetic short-range order in Ni at the Curie temperature."
    },
    {
        "anchor": "Formation of bulk ferromagnetic nanostructured Fe40Ni40P14B6 alloys by\n  metastable liquid spinodal decomposition: Nanostructured Fe40Ni40P14B6 alloys ingots of diameter 3~5 mm could be\nsynthesised by a metastable liquid state spinodal decomposition method. The\nmolten Fe40Ni40P14B6 alloy was purified by means of the fluxing technique and\nthus a large undercooling could be achieved. For undercooling Delta T > 260 K,\nthe microstructure of the undercooled specimen had exhibited liquid state\nspinodal decomposition in the undercooled liquid state. The microstructure\ncould be described as two intertwining networks with small grains dispersed in\nthem. For undercooling Delta T > 290 K, the overall microstructure of the\nspecimen changed into a granular morphology. The average grain sizes of the\nsmall and large grains are ~ 30 nm and ~ 80 nm, respectively. These prepared\nsamples are soft magnets with saturation magnetization Bs ~0.744 T.",
        "positive": "Ultrastrong and Ultrastable Metallic Glass: The lack of thermal stability, originating from their metastable nature, has\nbeen one of the paramount obstacles that hinder the wide range of applications\nof metallic glasses. We report that the stability of a metallic glass can be\ndramatically improved by slow deposition at high temperatures. The glass\ntransition and crystallization temperatures of the ultrastable metallic glass\ncan be increased by 51 K and 203 K, respectively, from its ordinary glass\nstate. The ultrastable metallic glass also shows ultrahigh strength and\nhardness, over 30 % higher than its ordinary counterpart. Atomic structure\ncharacterization reveals that the exceptional properties of the ultrastable\nglass are associated with abundance of medium range order. The finding of the\nultrastable metallic glass sheds light on atomic mechanisms of metallic glass\nformation and has important impact on the technological applications of\nmetallic glasses."
    },
    {
        "anchor": "Detecting Chiral Orbital Angular Momentum by Circular Dichroism ARPES: We show, by way of tight-binding and first-principles calculations, that a\none-to-one correspondence between electron's crystal momentum k and non-zero\norbital angular momentum (OAM) is a generic feature of surface bands. The OAM\nforms a chiral structure in momentum space much as its spin counterpart in\nRashba model does, as a consequence of the inherent inversion symmetry breaking\nat the surface but not of spin-orbit interaction. Circular dichroism (CD)\nangle-resolved photoemission (ARPES) experiment is an efficient way to detect\nthis new order, and we derive formulas explicitly relating the CD-ARPES signal\nto the existence of OAM in the band structure. The cases of degenerate p- and\nd-orbital bands are considered.",
        "positive": "Non-linear conductivity of metals from real-time quantum simulations: We simulate bulk materials under strong currents by following in real-time\nthe dynamics of the electrons under an electric field. By changing the\nintensity of the electric field, our method can model, for the first time,\nnon-linear effects in the conductivity from first principles. To illustrate our\napproach, we show calculations that predict that liquid aluminum exhibits\nnegative-differential conductivity for current densities of the order of\n$10^{12}-10^{13}~\\mathrm{A/cm^2}$. We find that the change in the non-linear\nconductivity emerges from a competition between the accumulation of charge\naround the nuclei that increases the scattering of the conduction electrons,\nand a decreasing scattering cross-section at high currents."
    },
    {
        "anchor": "Revealing the chemical bonding in adatoms arrays via machine learning of\n  3D scanning tunneling spectroscopy data: The adatom arrays on surfaces offer an ideal playground to explore the\nmechanisms of chemical bonding via changes in the local electronic tunneling\nspectra. While this information is readily available in hyperspectral scanning\ntunneling spectroscopy data, its analysis has been considerably impeded by a\nlack of suitable analytical tools. Here we develop a machine learning based\nworkflow combining supervised feature identification in the spatial domain and\nun-supervised clustering in the energy domain to reveal the details of\nstructure-dependent changes of the electronic structure in adatom arrays on the\nCo3Sn2S2 cleaved surface. This approach, in combination with first-principles\ncalculations, provides insight for using artificial neural networks to detect\nadatoms and classifies each based on their local neighborhood comprised of\nother adatoms. These structurally classified adatoms are further spectrally\ndeconvolved. The unexpected inhomogeneity of electronic structures among\nadatoms in similar configurations is unveiled using this method, suggesting\nthere is not a single atomic species of adatoms, but rather multiple types of\nadatoms on the Co3Sn2S2 surface. This is further supported by a slight contrast\ndifference in the images (or slight size variation) of the topography of the\nadatoms.",
        "positive": "Structural phase transitions and magnetic superexchange in MIAgIIF3\n  perovskites at high pressure: Pressure induced phase transitions of MIAgIIF3 perovskites where M = K, Rb,\nCs, have been predicted theoretically for the first time for pressures up to\n100 GPa. The sequence of phase transitions for M = K and Rb consists of an\northorhombic to monoclinic and back to orthorhombic transition, associated with\nprogressive bending of infinite chains of corner sharing [AgF6]4 minus\noctahedra and their mutual approaching via secondary Ag...F contacts. In stark\ncontrast, only a single phase transition i.e. tetragonal to triclinic, is\npredicted for CsAgF3, associated with substantial deformation of the Jahn\nTeller-distorted first coordination sphere of AgII and association of the\ninfinite [AgF6]4 minus chains into a polymeric sublattice. The phase\ntransitions markedly decrease the coupling strength of intra-chain\nantiferromagnetic superexchange in MAgF3 hosts lattices."
    },
    {
        "anchor": "Correlation versus randomization of jerky flow in an AlMgScZr alloy\n  using acoustic emission: Jerky flow in solids results from collective dynamics of dislocations which\ngives rise to serrated deformation curves and a complex evolution of the strain\nheterogeneity. A rich example of this phenomenon is the Portevin-Le Chatelier\neffect in alloys. The corresponding spatiotemporal patterns showed some\nuniversal features which provided a basis for a well-known phenomenological\nclassification. Recent studies revealed peculiar features in both the stress\nserration sequences and the kinematics of deformation bands in Al-based alloys\ncontaining fine microstructure elements, such as nanosize precipitates and (or)\nsubmicron grains. In the present work, jerky flow of an AlMgScZr alloy is\nstudied using statistical analysis of stress serrations and the accompanying\nacoustic emission. As in the case of coarse-grained binary AlMg alloys, the\namplitude distributions of acoustic events obey a power-law scaling which is\nusually considered as evidence of avalanchelike dynamics. However, the scaling\nexponents display specific dependences on the strain and strain rate for the\ninvestigated materials. The observed effects bear evidence to a competition\nbetween the phenomena of synchronization and randomization of dislocation\navalanches, which may shed light on the mechanisms leading to a high variety of\njerky flow patterns observed in applied alloys.",
        "positive": "A route for the top-down fabrication of ordered ultrathin GaN nanowires: Ultrathin GaN nanowires (NWs) are attractive to maximize surface effects and\nas building block in high-frequency transistors. Here, we introduce a facile\nroute for the top-down fabrication of ordered arrays of GaN NWs with aspect\nratios exceeding $10$ and diameters below $20\\,$nm. Highly uniform thin GaN NWs\nare first obtained by using electron beam lithography to pattern a Ni/SiN$_x$\nhard mask, followed by dry etching and wet etching in hot KOH. The SiN$_x$ is\nfound to work as an etch stop during wet etching in hot KOH. Arrays with NW\ndiameters down to $(33 \\pm5)\\,$nm can be achieved with a yield exceeding\n$99.9\\,\\%$. Further reduction of the NW diameter down to $5\\,$nm is obtained by\napplying digital etching which consists in plasma oxidation followed by wet\netching in hot KOH. The NW radial etching depth is tuned by varying the RF\npower during plasma oxidation. NW breaking or bundling is observed for\ndiameters below $\\approx 20\\,$nm, an effect that is associated to capillary\nforces acting on the NWs during sample drying in air. This effect can be\nprincipally mitigated using critical point dryers. Interestingly, this\nmechanical instability of the NWs is found to occur at much smaller aspect\nratios than what is predicted for models dealing with macroscopic elastic rods.\nExplicit calculations of buckling states show an improved agreement when\nconsidering an inclined water surface, as can be expected if water assembles\ninto droplets. The proposed fabrication route can be principally applied to any\nGaN/SiN$_{x}$ nanostructures and allows regrowth after removal of the SiN$_{x}$\nmask."
    },
    {
        "anchor": "Tip and Surface Determination from Experiments and Simulations of\n  Scanning Tunneling Microscopy and Spectroscopy: We present a very efficient and accurate method to simulate scanning\ntunneling microscopy images and spectra from first-principles density\nfunctional calculations. The wave-functions of the tip and sample are\ncalculated separately on the same footing, and propagated far from the surface\nusing the vacuum Green's function. This allows to express the Bardeen matrix\nelements in terms of convolutions, and to obtain the tunneling current at all\ntip positions and bias voltages in a single calculation. The efficiency of the\nmethod opens the door to real time determination of both tip and surface\ncomposition and structure, by comparing experiments to simulated images for a\nvariety of precomputed tips. Comparison with the experimental topography and\nspectra of the Si(111)-(7x7) surface show a much better agreement with Si than\nwith W tips, implying that the metallic tip is terminated by silicon.",
        "positive": "Silicon surface with giant spin-splitting: We demonstrate the induction of a giant Rashba-type spin-splitting on a\nsemiconducting substrate by means of a Bi trimer adlayer on a Si(111) wafer.\nThe in-plane inversion symmetry is broken so that the in-plane potential\ngradient induces a giant spin-splitting with a Rashba energy of about 140 meV,\nwhich is more than an order of magnitude larger than what has previously been\nreported for any semiconductor heterostructure. The separation of the\nelectronic states is larger than their lifetime broadening, which has been\ndirectly observed with angular resolved photoemission spectroscopy. The\nexperimental results are confirmed by relativistic first-principles\ncalculations. We envision important implications for basic phenomena as well as\nfor the semiconductor based technology."
    },
    {
        "anchor": "Phonon Raman scattering of RCrO3 perovskites (R = Y, La, Pr, Sm, Gd, Dy,\n  Ho, Yb, Lu): We report a systematic investigation of orthorhombic perovskite-type RCrO3\npowder samples by Raman scattering for nine different rare earth R3+ cations (R\n= Y, La, Pr, Sm, Gd, Dy, Ho, Yb, Lu). The room-temperature Raman spectra and\nthe associated phonon mode assignment provide reference data for structural\ninvestigation of the whole series of RCrO3 orthochromites and phonon ab-initio\ncalculations. The assignment of the chromite spectra and comparison with Raman\ndata on other orthorhombic perovskites allows correlating the phonon modes with\nthe structural distortions in the RCrO3 series. In particular, two Ag modes are\nidentified as octahedra rotation soft modes as their positions scale linearly\nwith the octahedra tilt angle of the CrO6 octahedra.",
        "positive": "Lattice anharmonicity and thermal conductivity from compressive sensing\n  of first-principles calculations: First-principles prediction of lattice thermal conductivity $\\kappa_L$ of\nstrongly anharmonic crystals is a long-standing challenge in solid state\nphysics. Making use of recent advances in information science, we propose a\nsystematic and rigorous approach to this problem, compressive sensing lattice\ndynamics (CSLD). Compressive sensing is used to select the physically important\nterms in the lattice dynamics model and determine their values in one shot.\nNon-intuitively, high accuracy is achieved when the model is trained on\nfirst-principles forces in {\\it quasi-random\\/} atomic configurations. The\nmethod is demonstrated for Si, NaCl, and Cu$_{12}$Sb$_4$S$_{13}$, an\nearth-abundant thermoelectric with strong phonon-phonon interactions that limit\nthe room-temperature $\\kappa_L$ to values near the amorphous limit."
    },
    {
        "anchor": "DFT Studies of 2D Materials Inspired by Lie Algebras: Inspired by the root systems of Lie algebras of rank 2, we propose a\nmathematical method to engineer new 2D materials with double periodic\nstructures tessellating the plane. Concretely, we investigate two geometries\nrelaying on squares and hexagons exhibiting D4 D4 and D6 D6 dihedral group\ninvariances, respectively. Due to lack of empirical verifications of such\ndouble configurations, we provide a numerical investigation by help of the open\nsource quantum espresso. Motivated by hybrid structures of graphene, silicene,\ngermanene, we investigate two models involving D4 D4 and D6 D6 dihedral\nsymmetries which we refer to as Si4Ge4 and Si6C6 compounds, respectively. For\nsimplicities, we study only the opto-electronic physical properties by applying\nan electromagnetic source propagating in linear and isotropic mediums. We\nbelieve that the Lie algebra inspiration of such 2D material studies, via\ndensity functional theory techniques, could open new roads to think about\nhigher dimensional cases by implementing generalized Cartan matrices.",
        "positive": "Understanding the Geometric Diversity of Inorganic and Hybrid Frameworks\n  through Structural Coarse-Graining: Much of our understanding of complex structures is based on simplification:\nfor example, metal-organic frameworks are often discussed in the context of\n\"nodes\" and \"linkers\", allowing for a qualitative comparison with simpler\ninorganic structures. Here we show how such an understanding can be obtained in\na systematic and quantitative framework, by combining atom-density based\nsimilarity (kernel) functions and unsupervised machine learning with the\nlong-standing idea of \"coarse-graining\" atomic structure. We demonstrate how\nthe latter enables a comparison of vastly different chemical systems, and use\nit to create a unified, two-dimensional structure map of experimentally known\ntetrahedral AB2 networks - including clathrate hydrates, zeolitic imidazolate\nframeworks (ZIFs), and diverse inorganic phases. The structural relationships\nthat emerge can then be linked to microscopic properties of interest, which we\nexemplify for structural heterogeneity and tetrahedral density."
    },
    {
        "anchor": "Structural disjoining potential for grain boundary premelting and grain\n  coalescence from molecular-dynamics simulations: We describe a molecular dynamics framework for the direct calculation of the\nshort-ranged structural forces underlying grain-boundary premelting and\ngrain-coalescence in solidification. The method is applied in a comparative\nstudy of (i) a Sigma 9 <115> 120 degress twist and (ii) a Sigma 9 <110> {411}\nsymmetric tilt boundary in a classical embedded-atom model of elemental Ni.\nAlthough both boundaries feature highly disordered structures near the melting\npoint, the nature of the temperature dependence of the width of the disordered\nregions in these boundaries is qualitatively different. The former boundary\ndisplays behavior consistent with a logarithmically diverging premelted layer\nthickness as the melting temperature is approached from below, while the latter\ndisplays behavior featuring a finite grain-boundary width at the melting point.\nIt is demonstrated that both types of behavior can be quantitatively described\nwithin a sharp-interface thermodynamic formalism involving a width-dependent\ninterfacial free energy, referred to as the disjoining potential. The\ndisjoining potential for boundary (i) is calculated to display a monotonic\nexponential dependence on width, while that of boundary (ii) features a weak\nattractive minimum. The results of this work are discussed in relation to\nrecent simulation and theoretical studies of the thermodynamic forces\nunderlying grain-boundary premelting.",
        "positive": "Thermally stimulated H emission and diffusion in hydrogenated amorphous\n  silicon: We report first principles ab initio density functional calculations of\nhydrogen dynam- ics in hydrogenated amorphous silicon. Thermal motion of the\nhost Si atoms drives H diffusion, as we demonstrate by direct simulation and\nexplain with simple models. Si-Si bond centers and Si ring centers are local\nenergy minima as expected. We also describe a new mechanism for break- ing Si-H\nbonds to release free atomic H into the network: a fluctuation bond center\ndetachment (FBCD) assisted diffusion. H dynamics in a-Si:H is dominated by\nstructural fluctuations intrinsic to the amorphous phase not present in the\ncrystal."
    },
    {
        "anchor": "The role of surface plasmons in the decay of image-potential states on\n  silver surfaces: The combined effect of single-particle and collective surface excitations in\nthe decay of image-potential states on Ag surfaces is investigated, and the\norigin of the long-standing discrepancy between experimental measurements and\nprevious theoretical predictions for the lifetime of these states is\nelucidated. Although surface-plasmon excitation had been expected to reduce the\nimage-state lifetime, we demonstrate that the subtle combination of the spatial\nvariation of s-d polarization in Ag and the characteristic non-locality of\nmany-electron interactions near the surface yields surprisingly long\nimage-state lifetimes, in agreement with experiment.",
        "positive": "Parallel and anti-parallel helical surface states for topological\n  semimetals: Weyl points, carrying a Z-type monopole charge C, have bulk-surface\ncorrespondence (BSC) associated with helical surface states (HSSs). When |C| >\n1, multi-HSSs can appear in a parallel manner. However, when a pair of Weyl\npoints carrying C = \\pm 1 meet, a Dirac point carrying C = 0 can be obtained\nand the BSC vanishes. Nonetheless, a recent study in Ref. [arXiv:2201.03238]\nshows that a new BSC can survive for Dirac points when the system has\ntime-reversal (T )-glide (G) symmetry ({\\Theta}=TG), i.e., anti-parallel\ndouble/quad-HSSs associated with a new Z2-type monopole charge Q appears. In\nthis paper, we systematically review and discuss both the parallel and\nanti-parallel multi-HSSs for Weyl and Dirac points, carrying two different\nkinds of monopole charges. Two material examples are offered to understand the\nwhole configuration of multi-HSSs. One carries the Z-type monopole charge C,\nshows both local and global topology for three kinds of Weyl points, and it\nleads to parallel multi-HSSs. The other carries the Z2-type monopole charge Q,\nonly showing the global topology for {\\Theta}-invariant Dirac points, and it is\naccompanied by antiparallel multi-HSSs. These diverse topological surface\nstates not only offer the local and global topology for the bulk degeneracy but\nalso offer platforms to various topological phases."
    },
    {
        "anchor": "Magnetic anisotropy of La0.7Sr0.3MnO3 nanopowders: The magnetic anisotropy of La0.7Sr0.3MnO3 nanopowders was measured as a\nfunction of temperature by the modified singular point detection technique. In\nthis method singularities indicating the anisotropy field were determined\nanalyzing ac susceptibility data. The observed relationship between temperature\ndependence of anisotropy constant and temperature dependence of magnetization\nwas used to deduce the origin of magnetic anisotropy in the nanopowders. It was\nshown that magnetic anisotropy of La0.7Sr0.3MnO3 nanopowder is determined by\ntwo-ion (dipolar or pseudodipolar) and single-ion mechanisms.",
        "positive": "Direct Observation and Control of Surface Termination in Perovskite\n  Oxide Heterostructures: The interfacial behavior of quantum materials leads to emergent phenomena\nsuch as two dimensional electron gases, quantum phase transitions, and\nmetastable functional phases. Probes for in situ and real time surface\nsensitive characterization are critical for active monitoring and control of\nepitaxial synthesis, and hence the atomic-scale engineering of heterostructures\nand superlattices. Termination switching, especially as an interfacial process\nin ternary complex oxides, has been studied using a variety of probes, often ex\nsitu; however, direct observation of this phenomena is lacking. To address this\nneed, we establish in situ and real time reflection high energy electron\ndiffraction and Auger electron spectroscopy for pulsed laser deposition, which\nprovide structural and compositional information of the surface during film\ndeposition. Using this unique capability, we show, for the first time, the\ndirect observation and control of surface termination in complex oxide\nheterostructures of SrTiO3 and SrRuO3. Density-functional-theory calculations\ncapture the energetics and stability of the observed structures and elucidate\ntheir electronic behavior. This demonstration opens up a novel approach to\nmonitor and control the composition of materials at the atomic scale to enable\nnext-generation heterostructures for control over emergent phenomena, as well\nas electronics, photonics, and energy applications."
    },
    {
        "anchor": "Trapping of electrons near chemisorbed hydrogen on graphene: Chemical adsorption of atomic hydrogen on a negatively charged single layer\ngraphene sheet has been analyzed with ab-initio Density Functional Theory\ncalculations. We have simulated both finite clusters and infinite periodic\nsystems to investigate the effect of different ingredients of the theory, e.g.\nexchange and correlation potentials, basis sets, etc. Hydrogen's electron\naffinity dominates the energetic balance in the charged systems and the extra\nelectron is predominantly attracted to a region nearby the chemisorbed atom.\nThe main consequences are: (i) the cancellation of the unpaired spin resulting\nin a singlet ground-state, and (ii) a stronger interaction between hydrogen and\nthe graphene sheet.",
        "positive": "Theoretical study of kinetics of proton coupled electron transfer in\n  photocatalysis: Photocatalysis induced by sunlight is one of the most promising approach to\nenvironmental protection, solar energy conversion and sustainable production of\nfuels. The computational modeling of photocatalysis is a rapidly expending\nfield which requires to adapt and further develop the available theoretical\ntools. The coupled transfer of proton and electron is an important reaction\nduring photocatalysis. In this work, we present the first step of our\nmethodology development in which we apply existing kinetic theory of such\ncoupled transfer to a model system, namely, methanol photo-dissociation on\nrutile TiO$_2$(110) surface, with the help of high-level first-principles\ncalculations. Moreover, we adapt the Stuchebrukhov-Hammes-Schiffer kinetic\ntheory, where we use the Georgievskii-Stuchebrukhova vibronic coupling, to\ncalculate the rate constant of the proton coupled electron transfer reaction\nfor a particular pathway. In particular, we propose a modified expression to\ncalculate the rate constant which enforces the near-resonance condition for the\nvibrational wavefunction during proton tunneling."
    },
    {
        "anchor": "\"WM\"-Shaped Growth of GaN on Patterned Sapphire Substrates: In metal organic vapor phase epitaxy of GaN, the growth mode is sensitive to\nreactor temperature. In this study, V-pit-shaped GaN has been grown on normal\nc-plane cone-patterned sapphire substrate by decreasing the growth temperature\nof high-temperature-GaN to around 950 oC, which leads to the 3-dimensional\ngrowth of GaN. The so-called \"WM\" well describes the shape that the bottom of\nGaN V-pit is just right over the top of sapphire cone, and the regular\narrangement of V-pits follows the patterns of sapphire substrate strictly. Two\ntypes of semipolar facets (1101) and (1122) expose on sidewalls of V-pits.\nFurthermore, by raising the growth temperature to 1000 oC, the growth mode of\nGaN can be transferred to 2-demonsional growth. Accordingly, the size of V-pits\nbecomes smaller and the area of c-plane GaN becomes larger, while the total\nthickness of GaN keeps almost unchanged during this process. As long as the\n2-demonsional growth lasts, the V-pits will disappear and only flat c-plane GaN\nremains. This means the area ratio of c-plane and semipolar plane GaN can be\ncontrolled by the duration time of 2-demonsional growth.",
        "positive": "A Quantitative Analytical Model for Predicting and Optimizing the Rate\n  Performance of Battery Cells: An important objective of designing lithium-ion rechargeable battery cells is\nto maximize their rate performance without compromising the energy density,\nwhich is mainly achieved through computationally expensive numerical\nsimulations at present. Here we present a simple analytical model for\npredicting the rate performance of battery cells limited by electrolyte\ntransport without any fitting parameters. It exhibits very good agreement with\nsimulations over a wide range of discharge rate and electrode thickness and\noffers a speedup of >10$^5$ times. The optimal electrode properties predicted\nby the model are of less than 10% difference from simulation results,\nsuggesting it as an attractive computational tool for the cell-level battery\narchitecture design. The model also offers important insights on practical ways\nto improve the rate performance of thick electrodes, including avoiding\nelectrode materials such as LiFePO$_4$ and Li$_4$Ti$_5$O$_{12}$ whose\nopen-circuit potentials are insensitive to the state of charge and utilizing\nlithium metal anode to synergistically accelerate electrolyte transport within\nthick cathodes."
    },
    {
        "anchor": "Electrical expression of spin accumulation in ferromagnet/semiconductor\n  structures: We treat the spin injection and extraction via a ferromagnetic\nmetal/semiconductor Schottky barrier as a quantum scattering problem. This\nenables the theory to explain a number of phenomena involving spin-dependent\ncurrent through the Schottky barrier, especially the counter-intuitive spin\npolarization direction in the semiconductor due to current extraction seen in\nrecent experiments. A possible explanation of this phenomenon involves taking\ninto account the spin-dependent inelastic scattering via the bound states in\nthe interface region. The quantum-mechanical treatment of spin transport\nthrough the interface is coupled with the semiclassical description of\ntransport in the adjoining media, in which we take into account the in-plane\nspin diffusion along the interface in the planar geometry used in experiments.\nThe theory forms the basis of the calculation of spin-dependent current flow in\nmulti-terminal systems, consisting of a semiconductor channel with many\nferromagnetic contacts attached, in which the spin accumulation created by spin\ninjection/extraction can be efficiently sensed by electrical means. A\nthree-terminal system can be used as a magnetic memory cell with the bit of\ninformation encoded in the magnetization of one of the contacts. Using five\nterminals we construct a reprogrammable logic gate, in which the logic inputs\nand the functionality are encoded in magnetizations of the four terminals,\nwhile the current out of the fifth one gives a result of the operation.",
        "positive": "Picosecond laser structuration under high pressures: observation of\n  boron nitride nanorods: We report on picosecond UV-laser processing of hexagonal boron nitride (hBN)\nat moderately high pressures above 500 bar. The main effect is specific to the\nambient gas and laser pulse duration in the ablation regime: when samples are\nirradiated by 5 ps or 0.45 ps laser pulses in nitrogen gas environment,\nmultiple nucleation of a new crystalline product - BN nanorods - takes place.\nThis process is triggered on structural defects, which number density strongly\ndecreases upon recrystallization. Non-linear photon absorption by adsorbed\nnitrogen molecules is suggested to mediate the nucleation-growth. High pressure\nis responsible for the confinement and strong backscattering of ablation\nproducts. A strong surface structuring also appears at longer 150-ps laser\nirradiation in similar experimental conditions. However, the transformed\nproduct in this case is amorphous strongly contaminated by boron suboxides\nBxOy."
    },
    {
        "anchor": "Fracture as a pattern formation process: A continuum model of crack propagation is presented and discussed. We obtain\nsteady state solutions with a self-consistently selected propagation velocity\nand shape of the crack, provided that elastodynamic and viscoelastic effects\nare taken into account. Two different mechanism of crack propagation, a first\norder phase transition and surface diffusion are considered, and we discuss\ndifferent loading modes. The arising free boundary problems are solved by phase\nfield methods and a sharp interface approach using a multipole expansion\ntechnique.",
        "positive": "Magnetodielectric and magnetoelastic coupling in TbFe3(BO3)4: We have studied the magnetodielectric and magnetoelastic coupling in\nTbFe3(BO3)4 single crystals by means of capacitance, magnetostriction and Raman\nspectroscopy measurements. The data reveal strong magnetic field effects on the\ndielectric constant and on the macroscopic sample length which are associated\nto long range magnetic ordering and a field-driven metamagnetic transition. We\ndiscuss the coupling of the dielectric, structural, and magnetic order\nparameters and attribute the origin of the magnetodielectric coupling to phonon\nmode shifts according to the Lyddane-Sachs-Teller (LST) relation."
    },
    {
        "anchor": "Equilibrium, Metastability, and Hysteresis in a Model Spin-crossover\n  Material with Nearest-neighbor Antiferromagnetic-like and Long-range\n  Ferromagnetic-like Interactions: Phase diagrams and hysteresis loops were obtained by Monte Carlo simulations\nand a mean-field method for a simplified model of a spin-crossover material\nwith a two-step transition between the high-spin and low-spin states. This\nmodel is a mapping onto a square-lattice $S=1/2$ Ising model with\nantiferromagnetic nearest-neighbor and ferromagnetic Husimi-Temperley\n(equivalent-neighbor) long-range interactions. Phase diagrams obtained by the\ntwo methods for weak and strong long-range interactions are found to be\nsimilar. However, for intermediate-strength long-range interactions, the Monte\nCarlo simulations show that tricritical points decompose into pairs of critical\nendpoints and mean-field critical points surrounded by horn-shaped regions of\nmetastability. Hysteresis loops along paths traversing the horn regions are\nstrongly reminiscent of thermal two-step transition loops with hysteresis,\nrecently observed experimentally in several spin-crossover materials. We\nbelieve analogous phenomena should be observable in experiments and simulations\nfor many systems that exhibit competition between local antiferromagnetic-like\ninteractions and long-range ferromagnetic-like interactions caused by elastic\ndistortions.",
        "positive": "Crystal structure and magnetic modulation in beta-Ce2O2FeSe2: We report a combination of X-ray and neutron diffraction studies, Mossbauer\nspectroscopy and muon spin relaxation (muSR) measurements to probe the\nstructure and magnetic properties of the semiconducting beta-Ce2O2FeSe2\noxychalcogenide. We report a new structural description in space group Pna21\nwhich is consistent with diffraction data and second harmonic generation\nmeasurements and reveal an order-disorder transition on one Fe site at TOD ~\n330 K. Susceptibility measurements, Mossbauer and muSR reveal antiferromagnetic\nordering below TN = 86 K and more complex short range order above this\ntemperature. 12 K neutron diffraction data reveal a modulated magnetic\nstructure with q = 0.444 bN*."
    },
    {
        "anchor": "Complete mapping of magnetic anisotropy for prototype Ising van der\n  Waals FePS$_3$: Several Ising-type magnetic van der Waals (vdW) materials exhibit stable\nmagnetic ground states. Despite these clear experimental demonstrations, a\ncomplete theoretical and microscopic understanding of their magnetic anisotropy\nis still lacking. In particular, the validity limit of identifying their\none-dimensional (1-D) Ising nature has remained uninvestigated in a\nquantitative way. Here we performed the complete mapping of magnetic anisotropy\nfor a prototypical Ising vdW magnet FePS$_3$ for the first time. Combining\ntorque magnetometry measurements with their magnetostatic model analysis and\nthe relativistic density functional total energy calculations, we successfully\nconstructed the three-dimensional (3-D) mappings of the magnetic anisotropy in\nterms of magnetic torque and energy. The results not only quantitatively\nconfirm that the easy axis is perpendicular to the $ab$ plane, but also reveal\nthe anisotropies within the $ab$, $ac$, and $bc$ planes. Our approach can be\napplied to the detailed quantitative study of magnetism in vdW materials.",
        "positive": "Quantitative comparison of different approaches for reconstructing the\n  carbon-binder domain from tomographic image data of cathodes in lithium-ion\n  batteries and its influence on electrochemical properties: It is well known that the spatial distribution of the carbon-binder domain\n(CBD) offers a large potential to further optimize lithium-ion batteries.\nHowever, it is challenging to reconstruct the CBD from tomographic image data\nobtained by synchrotron tomography. In the present paper, we consider several\napproaches to segment 3D image data of two different cathodes into three\nphases, namely active material, CBD and pores. More precisely, we focus on\nglobal thresholding, a local closing approach based on EDX data, a k-means\nclustering method, and a procedure based on a neural network that has been\ntrained by correlative microscopy, i.e., based on data gained by synchrotron\ntomography and FIB-SEM data representing the same electrode. We quantify the\nimpact of the considered segmentation approaches on morphological\ncharacteristics as well as on the resulting performance by spatially-resolved\ntransport simulations. Furthermore, we use experimentally determined\nelectrochemical properties to identify an appropriate range for the effective\ntransport parameter of the CBD. The developed methodology is applied to two\ndifferently manufactured cathodes, namely an ultra-thick unstructured cathode\nand a two-layer cathode with varying CBD content in both layers. This\ncomparison elucidates the impact of a specific structuring concept on the 3D\nmicrostructure of cathodes."
    },
    {
        "anchor": "An equivalent expression of Z2 Topological Invariant for band insulators\n  using Non-Abelian Berry's connection: We introduce a new expression for the Z2 topological invariant of band\ninsulators using non- Abelian Berry's connection. Our expression can identify\nthe topological nature of a general band insulator without any of the gauge\nfixing problems that plague the concrete implementation of previous invariants.\nThe new expression can be derived from the \"partner switching\" of the Wannier\nfunction center during time reversal pumping and is thus equivalent to the Z2\ntopological invariant proposed by Kane and Mele.",
        "positive": "Theory and applications of generalized Pipek--Mezey Wannier functions: The theory for the generation of Wannier functions within the generalized\nPipek--Mezey approach [Lehtola, S.; J\\'onsson, H. J. Chem. Theory Comput. 2014,\n10, 642] is presented and an implementation thereof is described. Results are\npresented for systems with periodicity in one, two and three dimensions as well\nas isolated molecules. The generalized Pipek--Mezey Wannier functions (PMWF)\nare highly localized orbitals consistent with chemical intuition where a\ndistinction is maintained between {\\sigma}- and {\\pi}-orbitals. The PMWF method\nis compared with the so-called maximally localized Wannier functions (MLWF)\nthat are frequently used for the analysis of condensed matter calculations.\nWhereas PMWFs maximize the localization criterion of Pipek and Mezey, MLWFs\nmaximize that of Foster and Boys and have the disadvantage of mixing {\\sigma}-\nand {\\pi}-orbitals in many cases. The PMWF orbitals turn out to be as localized\nas the MLWF orbitals as evidenced by cross-comparison of the values of the PMWF\nand MLWF objective functions for the two types of orbitals. Our implementation\nin the atomic simulation environment (ASE) is compatible with various\nrepresentations of the wave function, including real-space grids, plane waves\nand linear combinations of atomic orbitals. The projector augmented wave\nformalism for the representation of atomic core electrons is also supported.\nResults of calculations with the GPAW software are described here, but our\nimplementation can also use output from other electronic structure software\nsuch as ABINIT, NWChem and VASP."
    },
    {
        "anchor": "Biaxial growth of pentacene on rippled silica surfaces studied by\n  rotating grazing incidence X-ray diffraction: Pentacene is known to grow on isotropic silicon oxide surfaces in a\nsubstrate-induced phase with fiber textured crystallites. This growth study\nreports on the growth of pentacene crystallites on uniaxially oriented\nsurfaces. Silica substrates have been treated by ion beam sputtering so that\nripples with a lateral corrugation length of 38 nm and a surface roughness of\n1.3 nm are formed. Pentacene thin films with a nominal thickness in the range\nfrom 20 nm up to 300 nm are deposited on top of the rippled surfaces. The films\nare characterized by atomic force microscopy and grazing incidence X-ray\ndiffraction. Bi-axially oriented crystals are formed due to the grooves of the\nsubstrate surface opening up the possibility of a defined in-plane alignment of\nthe crystals. In a first stage of thin film growth, the thin film phase (TFP)\nof pentacene is formed, while in the later stage the bulk crystal structure (C,\nCampbell phase) also appears. Due to the bi-axial alignment of the crystallites\nthe transition from the thin film phase to the bulk crystal structure can be\ndirectly investigated. An epitaxial relationship with (120)TFP || (210)C and\n[-210]TFP || [1-20]C is observed which can be explained by an adaption of the\nherringbone layers of both crystal structures. This work reveals one possible\nmicroscopic mechanism for the transition from the metastable substrate-induced\nphase of pentacene to its equilibrium bulk structure.",
        "positive": "Ballistic magnetoresistance in nickel single-atom conductors: Large ballistic magnetoresistance (BMR) has been measured in Ni single-atom\nconductors electrodeposited between microfabricated thin films. These\nmeasurements irrefutably eliminate any magnetostriction related artifacts in\nthe BMR effect."
    },
    {
        "anchor": "Thermodynamic aspects of materials' hardness: prediction of novel\n  superhard high-pressure phases: In the present work we have proposed the method that allows one to easily\nestimate hardness and bulk modulus of known or hypothetical solid phases from\nthe data on Gibbs energy of atomization of the elements and corresponding\ncovalent radii. It has been shown that hardness and bulk moduli of compounds\nstrongly correlate with their thermodynamic and structural properties. The\nproposed method may be used for a large number of compounds with various types\nof chemical bonding and structures; moreover, the temperature dependence of\nhardness may be calculated, that has been performed for diamond and cubic boron\nnitride. The correctness of this approach has been shown for the recently\nsynthesized superhard diamond-like BC5. It has been predicted that the\nhypothetical forms of B2O3, diamond-like boron, BCx and COx, which could be\nsynthesized at high pressures and temperatures, should have extreme hardness.",
        "positive": "Laws of volume elasticity of the physical processes and the parameter\n  effect: We consider the mechanism of elastic strains and stresses as the main\ncontrolling factor of structure change under the influence of temperature,\nmagnetic field, hydrostatic pressure. We should take into account that the\nenergy of elastic deformation is commensurate to the energy of electric\ninteractions and that is much higher than the rest of the bonds of lower energy\nvalue. Besides, the energy elastic stresses are of long range, so it forms the\nlinearity in magnetization and bulk change. These regularities requires a\nfundamental understanding of the laws of interaction with respect to accepted\ninterpretation of quantum mechanical forces of short range that are attributes\nof magnetism formation. Due to the high sensitivity of electronic and resonance\nproperties with respect to small changes of the structure, we were able to\ndefine the direct relation between elastic stresses and field-frequency\ndependencies, as well as to analyze the evolution of the dynamics of phase\ntransitions and phase states. A cycle of studies of the influence of\nhydrostatic pressure on the resonance properties are presented also. The\nanalysis of the effect of magnetic, magneto-elastic and elastic energy allowed\nus to define the combinations of magneto-elastic interactions. The role of\nelastic stresses in the linear changes of the magnetostriction, magnetization,\nmagnetoelasticity of single-crystal magnetic semiconductors is described in\ndetails."
    },
    {
        "anchor": "Magnetic anisotropy in (Ga,Mn)As: Influence of epitaxial strain and hole\n  concentration: We present a systematic study on the influence of epitaxial strain and hole\nconcentration on the magnetic anisotropy in (Ga,Mn)As at 4.2 K. The strain was\ngradually varied over a wide range from tensile to compressive by growing a\nseries of (Ga,Mn)As layers with 5% Mn on relaxed graded (In,Ga)As/GaAs\ntemplates with different In concentration. The hole density, the Curie\ntemperature, and the relaxed lattice constant of the as-grown and annealed\n(Ga,Mn)As layers turned out to be essentially unaffected by the strain.\nAngle-dependent magnetotransport measurements performed at different magnetic\nfield strengths were used to probe the magnetic anisotropy. The measurements\nreveal a pronounced linear dependence of the uniaxial out-of-plane anisotropy\non both strain and hole density. Whereas the uniaxial and cubic in-plane\nanisotropies are nearly constant, the cubic out-of-plane anisotropy changes\nsign when the magnetic easy axis flips from in-plane to out-of-plane. The\nexperimental results for the magnetic anisotropy are quantitatively compared\nwith calculations of the free energy based on a mean-field Zener model. An\nalmost perfect agreement between experiment and theory is found for the\nuniaxial out-of-plane and cubic in-plane anisotropy parameters of the as-grown\nsamples. In addition, magnetostriction constants are derived from the\nanisotropy data.",
        "positive": "Probing magnon-magnon coupling in exchange coupled\n  Y$_3$Fe$_5$O$_{12}$/Permalloy bilayers with magneto-optical effects: We demonstrate the magnetically-induced transparency (MIT) effect in\nY$_3$Fe$_5$O$_{12}$(YIG)/Permalloy(Py) coupled bilayers. The measurement is\nachieved via a heterodyne detection of the coupled magnetization dynamics using\na single wavelength that probes the magneto-optical Kerr and Faraday effects of\nPy and YIG, respectively. Clear features of the MIT effect are evident from the\ndeeply modulated ferromagnetic resonance of Py due to the\nperpendicular-standing-spin-wave of YIG. We develop a phenomenological model\nthat nicely reproduces the experimental results including the induced amplitude\nand phase evolution caused by the magnon-magnon coupling. Our work offers a new\nroute towards studying phase-resolved spin dynamics and hybrid magnonic\nsystems."
    },
    {
        "anchor": "Stability, efficiency, and mechanism of n-type doping by hydrogen\n  adatoms in two-dimensional transition metal dichalcogenides: Mono- and few-layer transition-metal dichalcogenides (TMDCs) provide\nopportunities for ideal two-dimensional semiconductors for electronic and\noptoelectronic devices. For electronic devices on TMDCs, it is essential to\nincorporate n- and/or p-type dopants which are stable in positions after\npatterned doping. Here we investigate hydrogen doping for TMDC (MX2 with M =\nMo, W and X = S, Se, Te) nanosheets by first-principles calculations to address\ndiffusion and doping properties. We find that adsorbed hydrogen atoms in TMDCs\nare energetically most stable at the interstitial site right on the Mo or W\nplane and have substantial energy barriers against diffusion that increase in\nthe order of sulfides, selenides, and tellurides. Located at the most stable\ninterstitial site on the Mo or W plane, the hydrogen atoms produce electrons in\nthe conduction bands in the extremely high rate of one electron per hydrogen\natom, without any defect state inside the band gap remarkably. We analyze the\nchemical bonding character around the dopant and the mechanism for such high\nefficiency of electron doping. We also consider properties of hydrogen\nmolecules and Te vacancies for comparison. Our work shows that hydrogen doping\nis the promising pathway to development of highly integrated electronic devices\non TMDCs",
        "positive": "Electronic Transport of Two-Dimensional Ultrawide Bandgap Material h-BeO: Two-dimensional ultrawide bandgap materials, with bandgaps significantly\nwider than 3.4 eV, have compelling potential advantages in nano high-power\nsemiconductor, deep-ultraviolet optoelectronics, and so on. Recently,\ntwo-dimensional layered h-BeO has been synthesized in the experiments. In the\npresent work, the first-principles calculations predict that monolayer h-BeO\nhas an indirect bandgap of 7.05 eV with the HSE functional. The ultrawide\nbandgap results from the two atomic electronegativity difference in the polar\nh-BeO. And the electronic transport properties are also systematically\ninvestigated by using the Boltzmann transport theory. The polar LO phonons of\nh-BeO can generate the macroscopic polarization field and strongly couple to\nelectrons by the Frohlich interaction. Limited by the electron-phonon\nscattering, monolayer h-BeO has a high mobility of 473 cm^2/Vs at room\ntemperature. Further studies indicate that the biaxial tensile strain can\nreduce the electronic effective mass and enhance the electron-phonon coupling\nstrength. The suitable strain can promote the mobility to ~1000 cm^2/Vs at room\ntemperature."
    },
    {
        "anchor": "Towards a theory of flow stress in multimodal polycrystalline\n  aggregates. Effects of dispersion hardening: We elaborate the recently introduced theory of flow stress, including yield\nstrength, in polycrystalline materials under quasi-static plastic deformations,\nthereby extending the case of single-mode aggregates to multimodal ones in the\nframework of a two-phase model which is characterized by the presence of\ncrystalline and grain-boundary phases. Both analytic and graphic forms of the\ngeneralized Hall-Petch relations are obtained for multimodal samples with BCC\n($\\alpha$-phase Fe), FCC (Cu, Al, Ni) and HCP (Cu, Al, Ni) and HCP\n($\\alpha$-Ti, Zr) crystalline lattices at $T=300K$ with different values of the\ngrain-boundary (second) phase. The case of dispersion hardening due to a\nnatural incorporation into the model of a third phase including additional\nparticles of doping materials is considered. The maximum of yield strength and\nthe respective extremal grain size of samples are shifted by changing both the\ninput from different grain modes and the values at the second and third phases.\nWe study the influence of multimodality and dispersion hardening on the\ntemperature-dimensional effect for yield strength within the range of\n$150-350K$.",
        "positive": "Surface defreezing of glasses: A glass surface may still flow below the bulk glass transition temperature,\nwhere the underlying bulk is frozen. Assuming the existence at T=T* of a bulk\nthermodynamical glass transition, we show that the glass-vapor interface is\ngenerally wetted by a liquid layer of thickness ~ -ln(T*-T) when T--> T*.\nContrary to standard surface melting of crystals however, the integrated value\nof the diffusivity across the interface remains finite for T-->T*. Difference\nin shape induced by bulk and by surface flow is discussed as a possible means\nof experimental detection of surface defreezing."
    },
    {
        "anchor": "Metal-insulator transition in quasi-one-dimensional HfTe3 in the\n  few-chain limit: The quasi-one-dimensional linear chain compound HfTe3 is experimentally and\ntheoretically explored in the few- to single-chain limit. Confining the\nmaterial within the hollow core of carbon nanotubes allows isolation of the\nchains and prevents the rapid oxidation which plagues even bulk HfTe3.\nHigh-resolution transmission electron microscopy combined with density\nfunctional theory calculations reveals that, once the triple-chain limit is\nreached, the normally parallel chains spiral about each other, and\nsimultaneously a short-wavelength trigonal anti-prismatic rocking distortion\noccurs that opens a significant energy gap. This results in a size-driven\nmetal-insulator transition.",
        "positive": "Lattice dynamics of BaTiO3, PbTiO3 and PbZrO3: a comparative\n  first-principles study: The full phonon dispersion relations of lead titanate and lead zirconate in\nthe cubic perovskite structure are computed using first-principles variational\ndensity-functional perturbation theory, with ab initio pseudopotentials and a\nplane-wave basis set. Comparison with the results previously obtained for\nbarium titanate shows that the change of a single constituent (Ba to Pb, Ti to\nZr) has profound effects on the character and dispersion of unstable modes,\nwith significant implications for the nature of the phase transitions and the\ndielectric and piezoelectric responses of the compounds. Examination of the\ninteratomic force constants in real space, obtained by a transformation which\ncorrectly treats the long-range dipolar contribution, shows that most are\nstrikingly similar, while it is the differences in a few key interactions which\nproduce the observed changes in the phonon dispersions. These trends suggest\nthe possibility of the transferability of force constants to predict the\nlattice dynamics of perovskite solid solutions."
    },
    {
        "anchor": "Study of the Physical Properties of the EuCoA$_2$As$_2$ Compound: A DFT\n  approach: In this study, we carried out an investigation of the EuCoA$_2$As$_2$\ncompound, focusing on its various physical properties. Our analysis covered the\nstructural, magnetic, electronic, optical, thermodynamic and thermoelectric\ncharacteristics of this compound. To carry out this study, we used density\nfunctional theory (DFT) implemented in the Wien2k software package. To\ndetermine the exchange-correlation potential, we used the GGA-PBE (Perdew,\nBurke and Ernzerhof) approach, taking spin-orbit coupling (SOC) into account.\nOur results indicate that the EuCoA$_2$As$_2$ compound exhibits metallic\nbehavior. In addition, we have determined that the compound's stable ground\nstate is the ferromagnetic (FM) phase. We have also calculated the Debye\ntemperature and the Gr\\\"uneisen parameter. In addition, we evaluated various\noptical properties, including electron energy loss, absorption coefficient,\nreal and imaginary dielectric tensors, and real and imaginary optical\nconductivity. We found that the compound has excellent absorption\ncharacteristics in the low and mid ultraviolet (UV) spectra. In addition, we\ninvestigated the electrical conductivity, Seebeck coefficient, electronic\nconductivity and thermal conductivity of the lattice. The results revealed that\nthe compound exhibits n-type behavior, with negative values for the Seebeck\ncoefficient. These results are analyzed in detail and provide valuable\ninformation on the properties of the EuCoA$_2$As$_2$ compound. Additionally,\nthe computed parameters were compared to those found in the literature. A good\ndeals have been revealed with the existing results.",
        "positive": "Generic energy formalism for reciprocal quadruplets within the\n  two-sublattice quasichemical model: Ever-increasing interests to more accurate thermodynamic predictions of phase\ndiagrams motivate more reliable thermodynamic models to be developed. The\nModified Quasichemical Model within the two-sublattice Quadruplet Approximation\n(MQMQA) was thus established in well response to these interests and\nmotivations. However, the model still needs to be further improved in order to\nhave better thermodynamic predictions of arbitrary reciprocal solutions. The\npresent paper proposes a new and generic formalism to characterize the Gibbs\nenergy of the ternary reciprocal quadruplet within the framework of the MQMQA.\nThe new formalism circumvents the problem spawned from solving the singular\nmatrix of mass equations. Resultantly, energy landscapes of reciprocal\nsolutions can be better defined everywhere in reciprocal composition spaces.\nWith the current improvement, the MQMQA is believed to be one of the most\nreliable thermodynamic models for various types of solutions with or without\nshort-range ordering."
    },
    {
        "anchor": "Light and electric field control of ferromagnetism in magnetic quantum\n  structures: A strong influence of illumination and electric bias on the Curie temperature\nand saturation value of the magnetization is demonstrated for semiconductor\nstructures containing a modulation-doped p-type Cd0.96Mn0.04Te quantum well\nplaced in various built-in electric fields. It is shown that both light beam\nand bias voltage generate an isothermal and reversible cross-over between the\nparamagnetic and ferromagnetic phases, in the way that is predetermined by the\nstructure design. The observed behavior is in quantitative agreement with the\nexpectations for systems, in which ferromagnetic interactions are mediated by\nthe weakly disordered two-dimensional hole liquid.",
        "positive": "ESR and TSL study of hole capture in PbWO_4:Mo,La and PbWO_4:Mo,Y\n  scintillator crystals: The processes of hole localization in double-doped PbWO_4:Mo,La and\nPbWO_4:Mo,Y single crystals have been studied by continuous wave and pulse\nelectron spin resonance (ESR) and thermally stimulated luminescence (TSL)\nmethods. We show that the holes created by the UV irradiation are preferably\ntrapped at lattice oxygen ions in the vicinity of perturbing defects such as\nlead vacancies, impurity ions (La, Y, Mo), and other lattice imperfections.\nThis leads to a variety of O^- centers, which differ both by thermal stability\n(from about 170 K up to 240 K) and ESR parameters. The hole centers of this\ntype were not observed neither in PbWO_4:Mo nor in PbWO_4:La(Y) crystals. The\nrecombination processes of thermally released holes with electrons stored at\ndifferent traps, including Pb^+ - WO_3 and (MoO_4)^3- centers, are\nsystematically studied by TSL. Thermal stability parameters are defined by ESR\nand TSL techniques for different O^- type defects."
    },
    {
        "anchor": "Acousto-electric Characteristics of Periodically Poled Ferroelectric\n  Plate: A multidomain two-dimensional periodically poled ferroelectric plate vibrator\nis reported for the first time. The theoretical calculations, computer\nsimulations by the Finite Element Method and experimental data from the lithium\ntantalite samples reveal a domain acousto-electric resonance. A polarization\ninversion in a y-rotated cut of a ferroelectric chip is firstly done. The\nacousto-electric characteristics of the vibrator are calculated and measured.",
        "positive": "Bloch oscillations and Wannier-Stark localization in semiconductor\n  superlattices: The theoretical analysis of the ultrafast energy relaxation and transport\nphenomena in semiconductor superlattices is reviewed. In particular, we discuss\nthe two equivalent quantum-mechanical pictures of Bloch oscillations and\nWannier-Stark localization. A review of simulated experiments and their\ncomparison with available experimental investigations is also provided."
    },
    {
        "anchor": "Hydrogen Diffusion and Stabilization in Single-crystal VO2\n  Micro/nanobeams by Direct Atomic Hydrogenation: We report measurements of the diffusion of atomic hydrogen in single\ncrystalline VO2 micro/nanobeams by direct exposure to atomic hydrogen, without\ncatalyst. The atomic hydrogen is generated by a hot filament, and the doping\nprocess takes place at moderate temperature (373 K). Undoped VO2 has a\nmetal-to-insulator phase transition at ~340 K between a high-temperature,\nrutile, metallic phase and a low-temperature, monoclinic, insulating phase with\na resistance exhibiting a semiconductor-like temperature dependence. Atomic\nhydrogenation results in stabilization of the metallic phase of VO2\nmicro/nanobeams down to 2 K, the lowest point we could reach in our measurement\nsetup. Based on observing the movement of the hydrogen diffusion front in\nsingle crystalline VO2 beams, we estimate the diffusion constant for hydrogen\nalong the c-axis of the rutile phase to be 6.7 x 10^{-10} cm^2/s at\napproximately 373 K, exceeding the value in isostructural TiO2 by ~ 38x.\nMoreover, we find that the diffusion constant along the c-axis of the rutile\nphase exceeds that along the equivalent a-axis of the monoclinic phase by at\nleast three orders of magnitude. This remarkable change in kinetics must\noriginate from the distortion of the \"channels\" when the unit cell doubles\nalong this direction upon cooling into the monoclinic structure. Ab initio\ncalculation results are in good agreement with the experimental trends in the\nrelative kinetics of the two phases. This raises the possibility of a\nswitchable membrane for hydrogen transport.",
        "positive": "Study of van der Waals bonding and interactions in metal organic\n  framework materials: Metal organic framework (MOF) materials have attracted a lot of attention due\nto their numerous applications in fields such as hydrogen storage, carbon\ncapture, and gas sequestration. In all these applications, van der Waals forces\ndominate the interaction between the small guest molecules and the walls of the\nMOFs. In this review article, we describe how a combined theoretical and\nexperimental approach can successfully be used to study those weak interactions\nand elucidate the adsorption mechanisms important for various applications. On\nthe theory side, we show that, while standard density functional theory is not\ncapable of correctly describing van der Waals interactions, functionals\nespecially designed to include van der Waals forces exist, yielding results in\nremarkable agreement with experiment. From the experimental point of view, we\nshow examples in which IR adsorption and Raman spectroscopy are essential to\nstudy molecule/MOF interactions. Importantly, we emphasize throughout this\nreview that a combination of theory and experiment is crucial to effectively\ngain further understanding. In particular, we review such combined studies for\nthe adsorption mechanism of small molecules in MOFs, the chemical stability of\nMOFs under humid conditions, water cluster formation inside MOFs, and the\ndiffusion of small molecules into MOFs. The understanding of these phenomena is\ncritical for the rational design of new MOFs with desired properties."
    },
    {
        "anchor": "Use of optically detected magnetic resonance to correlate germanium\n  electron centers with UV absorption bands in X-ray irradiated germanosilicate\n  glasses: The relationship between paramagnetic defect centers and UV absorption bands\nsimultaneously generated by ionizing radiation in Ge-doped SiO2 glass is\ninvestigated using magneto-optical techniques. A sample of 7.0 mol% Ge-doped\nSiO2 was exposed to X-ray radiation, which resulted in the formation of\nabsorption bands centered at 4.4 eV and 5.7 eV as well as electron spin\nresonance (ESR) signals attributed to the Ge(1) and Ge(2) defects. To isolate\nparamagnetic contributions to the induced optical absorption, the magnetic\ncircular dichroism absorption (MCDA) spectrum was measured at several different\ntemperatures over the range 2.00-6.21 eV. The optically detected magnetic\nresonance (ODMR) spectrum was then obtained at 4.42 eV via microwave-induced\nchanges in the MCDA signals in order to unambiguously correlate this optical\ntransition with a particular ESR signal. The ODMR data indicates that the Ge(1)\ncenter is responsible for this absorption band, providing the first unequivocal\ncorrelation of ESR and optical properties for this defect. In addition,\nevidence of a weakly absorbing paramagnetic defect was found at 5.65 eV that\nappears to be related to the Ge(2) center.",
        "positive": "Tailoring the magnetic properties of nanocrystalline Cu-Co alloys\n  prepared by high-pressure torsion and isothermal annealing: In this study, severe plastic deformation by high pressure torsion is used as\na fabrication method for nanocrystalline magnetic CuCo alloys in bulk\nquantities. By subsequent isothermal annealing, phase separation of the\nsupersaturated solid solutions can be obtained. The magnetic properties of the\nas-processed and annealed materials have been studied systemically and\ncorrelated to the evolving nanostructures investigated in detail by\ntransmission electron microscopy and atom probe tomography. By additional high\npressure torsion deformation at liquid nitrogen temperature the magnetic\nproperties of the Cu74Co26 alloy can be further tuned."
    },
    {
        "anchor": "Investigations of Graphene on SrTiO3 Single-Crystal using Confocal Raman\n  Spectroscopy: Graphene layers placed on SrTiO3 single-crystal substrates were investigated\nusing temperature-dependent confocal Raman spectroscopy. This approach\nsuccessfully resolved distinct Raman modes of graphene that are often\nuntraceable in conventional measurements due to the strong Raman scattering\nbackground of SrTiO3. Information on defects and strain states was obtained for\na few graphene/SrTiO3 samples that were synthesized by different techniques.\nThis confocal Raman spectroscopic approach can shed light on the investigation\nof not only this graphene/SrTiO3 system but also various two-dimensional\nlayered materials whose Raman modes interfere with their substrates.",
        "positive": "Imaging Spin Reorientation Transitions in Consecutive Atomic Co layers: By means of spin-polarized low-energy electron microscopy (SPLEEM) we show\nthat the magnetic easy-axis of one to three atomic-layer thick cobalt films on\nruthenium crystals changes its orientation twice during deposition:\none-monolayer and three-monolayer thick films are magnetized in-plane, while\ntwo-monolayer films are magnetized out-of-plane, with a Curie temperature well\nabove room temperature. Fully-relativistic calculations based on the Screened\nKorringa-Kohn-Rostoker (SKKR) method demonstrate that only for two-monolayer\ncobalt films the interplay between strain, surface and interface effects leads\nto perpendicular magnetization."
    },
    {
        "anchor": "High Temperature Ferromagnetism in Zn1-xMnxO semiconductor thin films: Clear evidence of ferromagnetic behavior at temperatures >400 K as well as\nspin polarization of the charge carriers have been observed in ZnMnO thin films\ngrown on Al2O3 and MgO substrates. The magnetic properties depended on the\nexact Mn concentration and the growth parameters. In well-characterized\nsingle-phase films, the magnetic moment is 4.8?B/Mn at 350 K, the highest\nmoment yet reported for any Mn doped magnetic semiconductor. Anomalous Hall\neffect shows that the charge carriers (electrons) are spin polarized and\nparticipate in the observed ferromagnetic behavior.",
        "positive": "Wafer-scale, epitaxial growth of single layer hexagonal boron nitride on\n  Pt(111): Single layer hexagonal boron nitride is produced on 2 inch Pt(111)/sapphire\nwafers. The growth with borazine vapour deposition at process temperatures\nbetween 1000 and 1300 K is in-situ investigated by photoelectron yield\nmeasurements. The growth kinetics is slower at higher temperatures and follows\na tanh$^2$ law which better fits for higher temperatures. The crystal-quality\nof h-BN/Pt(111) is inferred from scanning low energy electron diffraction (x-y\nLEED). The data indicate a strong dependence of the epitaxy on the growth\ntemperature. The dominant structure is an aligned coincidence lattice with 10\nh-BN on 9 Pt(1$\\times$1) unit cells and follows the substrate twinning at the\nmillimeter scale."
    },
    {
        "anchor": "Electronic structure of turbostratic graphene: We explore the rotational degree of freedom between graphene layers via the\nsimple prototype of the graphene twist bilayer, i.e., two layers rotated by\nsome angle $\\theta$. It is shown that, due to the weak interaction between\ngraphene layers, many features of this system can be understood by interference\nconditions between the quantum states of the two layers, mathematically\nexpressed as Diophantine problems. Based on this general analysis we\ndemonstrate that while the Dirac cones from each layer are always effectively\ndegenerate, the Fermi velocity $v_F$ of the Dirac cones decreases as $\\theta\\to\n0^\\circ$; the form we derive for $v_F(\\theta)$ agrees with that found via a\ncontinuum approximation in Phys. Rev. Lett., 99:256802, 2007. From tight\nbinding calculations for structures with $1.47^\\circ \\le \\theta < 30^\\circ$ we\nfind agreement with this formula for $\\theta \\gtrsim 5^\\circ$. In contrast, for\n$\\theta \\lesssim 5^\\circ$ this formula breaks down and the Dirac bands become\nstrongly warped as the limit $\\theta \\to 0$ is approached. For an ideal system\nof twisted layers the limit as $\\theta\\to0^\\circ$ is singular as for $\\theta >\n0$ the Dirac point is fourfold degenerate, while at $\\theta=0$ one has the\ntwofold degeneracy of the $AB$ stacked bilayer. Interestingly, in this limit\nthe electronic properties are in an essential way determined \\emph{globally},\nin contrast to the 'nearsightedness' [W. Kohn. Phys. Rev. Lett., 76:3168,\n1996.] of electronic structure generally found in condensed matter.",
        "positive": "Electrical manipulation of orbital occupancy and magnetic anisotropy in\n  manganites: Electrical manipulation of lattice, charge, and spin has been realized\nrespectively by the piezoelectric effect, field-effect transistor, and electric\nfield control of ferromagnetism, bringing about dramatic promotions both in\nfundamental research and industrial production. However, it is generally\naccepted that the orbital of materials are impossible to be altered once they\nhave been made. Here we use electric-field to dynamically tune the electronic\nphase transition in (La,Sr)MnO3 films with different Mn^4+/(Mn^3+ + Mn^4+)\nratios. The orbital occupancy and corresponding magnetic anisotropy of these\nthin films are manipulated by gate voltage in a reversible and quantitative\nmanner. Positive gate voltage increases the proportion of occupancy of the\norbital and magnetic anisotropy that were initially favored by strain\n(irrespective of tensile and compressive), while negative gate voltage reduces\nthe concomitant preferential orbital occupancy and magnetic anisotropy. Besides\nits fundamental significance in orbital physics, our findings might advance the\nprocess towards practical oxide-electronics based on orbital."
    },
    {
        "anchor": "Longitudinal evolution of magnetization of ferromagnets following\n  ultrafast demagnetization: Role of finite size and shape of demagnetized\n  region: A dependence of a relaxation rate on the shape of the demagnetized region for\na longitudinal evolution of total magnetization to its equilibrium value\nfollowing the ultrafast demagnetization is demonstrated. This shape-dependence\nis caused by a motion of the wave front inside the demagnetized region. The\ncontribution of the wave front for spherically symmetric shape of the\ndemagnetized region is up to 3 times and for cylindrically symmetric shape up\nto 2 times stronger than for one dimensional demagnetized region. This effect\ncan be observed after the demagnetization by a tightly focused femtosecond\nlaser pulse.",
        "positive": "Orbital-Specific Modeling of CO Chemisorption: We demonstrate that variations in molecular chemisorption energy on different\nmetals, different surface terminations, and different strain conditions can be\naccounted for by orbital-specific changes in the substrate electronic\nstructure. Our density functional theory data set, spanning three metals, two\nsurface terminations, and five strain states, is fit to a single model based on\ntight binding. A crucial aspect of the model is decomposition of the $d$-band\ninto contributions from the five $d$ atomic orbitals. This provides a\nrepresentation of the energy levels of the substrate that are directly relevant\nto the chemisorption bond, leading to accurate prediction of chemisorption\ntrends."
    },
    {
        "anchor": "Creation of X-Ray Transparency of Matter by Stimulated Elastic Forward\n  Scattering: X-ray absorption by matter has long been described by the famous Beer-Lambert\nlaw. Here we show how this fundamental law needs to be modified for\nhigh-intensity coherent x-ray pulses, now available at x-ray free electron\nlasers, due to the onset of stimulated elastic forward scattering. We present\nan analytical expression for the modified polarization-dependent Beer-Lambert\nlaw for the case of resonant core-to-valence electronic transitions and\nincident transform limited x-ray pulses. Upon transmission through a solid, the\nabsorption and dichroic contrasts are found to vanish with increasing x-ray\nintensity, with the stimulation threshold lowered by orders of magnitude\nthrough a super-radiative coherent effect. Our results have broad implications\nfor the study of matter with x-ray lasers.",
        "positive": "X-Ray Thomson scattering without the Chihara decomposition: X-Ray Thomson Scattering (XRTS) is an important experimental technique used\nto measure the temperature, ionization state, structure, and density of warm\ndense matter (WDM). The fundamental property probed in these experiments is the\nelectronic dynamic structure factor (DSF). In most models, this is decomposed\ninto three terms [Chihara, J. Phys. F: Metal Phys. {\\bf 17}, 295 (1987)]\nrepresenting the response of tightly bound, loosely bound, and free electrons.\nAccompanying this decomposition is the classification of electrons as either\nbound or free, which is useful for gapped and cold systems but becomes\nincreasingly questionable as temperatures and pressures increase into the WDM\nregime. In this work we provide unambiguous first principles calculations of\nthe dynamic structure factor of warm dense beryllium, independent of the\nChihara form, by treating bound and free states under a single formalism. The\ncomputational approach is real-time finite-temperature time-dependent density\nfunctional theory (TDDFT) being applied here for the first time to WDM. We\ncompare results from TDDFT to Chihara-based calculations for experimentally\nrelevant conditions in shock-compressed beryllium."
    },
    {
        "anchor": "Explaining the Virtual Universal Occurrence of Static Friction: Perturbation theory, simulations and scaling arguments predict that there\nshould be no static friction for two weakly interacting flat atomically smooth\nclean solid surfaces. The absence of static friction results from the fact that\nthe atomic level interfacial potential energy is much weaker than the elastic\npotential energy, which prevents the atoms from sinking to their interfacial\npotential minima. Consequently, we have essentially two rigid solids, for which\nthe forces at randomly distributed \"pinning sites\" cancel. It is shown here\nthat even fluctuations in the concentration of atomic level defects at the\ninterface do not account for static friction. It is also argued that the\nsliding of contacting asperities, which occurs when the problem is studied at\nthe multi-micron length scale, relative to each other involves the shearing of\nplanes of atoms. Since this results in a force for the interaction of two\nasperities which varies over sliding distances of the order of an atomic\nspacing, the contacting asperities at the surface are able to sink to their\ninterfacial potential minima, with negligible cost in elastic potential energy.\nThis results in static friction.",
        "positive": "Nonlocal Piezoresponse of LaAlO3/SrTiO3 Heterostructures: The hysteretic piezoelectric response in LaAlO3/SrTiO3 heterostructures can\nprovide important insights into the mechanism for interfacial conductance and\nits metastability under various conditions. We have performed a variety of\nnonlocal piezoelectric force microscopy experiments on 3 unit cell\nLaAlO3/SrTiO3 heterostructures. A hysteretic piezoresponse is observed under\nvarious environmental and driving conditions. The hysteresis is suppressed when\neither the sample is placed in vacuum or the interface is electrically\ngrounded. We present a simple physical model which can account for the observed\nphenomena."
    },
    {
        "anchor": "Controlling and distinguishing electronic transport of topological and\n  trivial surface states in a topological insulator: Topological insulators (TI), with characteristic Dirac-fermion topological\nsurface states (TSS), have emerged as a new class of electronic materials with\nrich potentials for both novel physics and device applications. However, a\nmajor challenge with realistic TI materials is to access, distinguish and\nmanipulate the electronic transport of TSS often obscured by other possible\nparallel conduction channels that include the bulk as well as a two-dimensional\nelectron gas (2DEG) formed near the surface due to bending of the bulk bands.\nSuch a (Schrodinger-fermion) 2DEG represents topologically-trivial surface\nstates, whose coexistence with the TSS has been revealed by angle resolved\nphotoemission spectroscopy. Here we show that simple manipulations of surface\nconditions can be used to access and control both types of surface states and\ntheir coexistence in bulk-insulating Bi2Te2Se, whose surface conduction is\nprominently manifested in temperature dependent resistance and nonlocal\ntransport. The trivial 2DEG and TSS can both exhibit clear Shubnikov-de Haas\noscillations in magnetoresistance, with different Berry phases ~0 and ~pi that\ndistinguish their different topological characters. We also report a deviation\nfrom the typical weak antilocalization behavior, possibly due to high mobility\nTSS. Our study enables distinguishing, controlling and harnessing electronic\ntransport of TI surface carriers with different topological natures.",
        "positive": "Observation of topological electronic structure in quasi-1D\n  superconductor TaSe3: Topological superconductors (TSCs), with the capability to host Majorana\nbound states that can lead to non-Abelian statistics and application in quantum\ncomputation, have been one of the most intensively studied topics in condensed\nmatter physics recently. Up to date, only a few compounds have been proposed as\ncandidates of intrinsic TSCs, such as doped topological insulator CuxBi2Se3 and\niron-based superconductor FeTe0.55Se0.45. Here, by carrying out synchrotron and\nlaser based angle-resolved photoemission spectroscopy (ARPES), we\nsystematically investigated the electronic structure of a quasi-1D\nsuperconductor TaSe3, and identified the nontrivial topological surface states.\nIn addition, our scanning tunneling microscopy (STM) study revealed a clean\ncleaved surface with a persistent superconducting gap, proving it suitable for\nfurther investigation of potential Majorana modes. These results prove TaSe3 as\na stoichiometric TSC candidate that is stable and exfoliable, therefore a great\nplatform for the study of rich novel phenomena and application potentials."
    },
    {
        "anchor": "Entropy-Dominated Dissipation in Sapphire Shock-Compressed up to 400 GPa\n  (4 Mbar): Sapphire (single-crystal Al2O3) is a representative Earth material and is\nused as a window and/or anvil in shock experiments. Pressure, for example, at\nthe core-mantle boundary is about 130 gigapascals (GPa). Defects induced by\n100-GPa shock waves cause sapphire to become opaque, which precludes measuring\ntemperature with thermal radiance. We have measured wave profiles of sapphire\ncrystals with several crystallographic orientations at shock pressures of 16,\n23, and 86 GPa. At 23 GPa plastic-shock rise times are generally quite long\n(~100 ns) and their values depend sensitively on the direction of shock\npropagation in the crystal lattice. The long rise times are probably caused by\nthe high strength of inter-atomic interactions in the ordered three-dimensional\nsapphire lattice. Our wave profiles and recent theoretical and laser-driven\nexperimental results imply that sapphire disorders without significant shock\nheating up to about 400 GPa, above which Al2O3 is amorphous and must heat. This\npicture suggests that the characteristic shape of shock compression curves of\nmany Earth materials at 100 GPa pressures is caused by a combination of entropy\nand temperature.",
        "positive": "Investigating Polaron Formation in Anatase and Brookite TiO2 by Density\n  Functional Theory with Hybrid-Functional and DFT + U Methods: Anatase and brookite are robust materials with enhanced photocatalytic\nproperties. In this study, we used density functional theory (DFT) with a\nhybrid functional and the Hubbard on-site potential methods to determine\nelectron and hole polaron geometries for anatase and brookite and their\nenergetics. Localized electron and hole polarons were predicted not to form in\nanatase using DFT with hybrid functionals. In contrast, brookite formed both\nelectron and hole polarons. The brookite electron-polaronic solution exhibits\ncoexisting localized and delocalized states, with hole polarons mainly\ndispersed on two-coordinated oxygen ions. The Hubbard on-site potential testing\nover the wide range of 4 eV to 10 eV revealed that brookite polarons are formed\nat 6 eV, while anatase polarons are formed at 8 eV. The brookite electron\npolaron was always localized on a single titanium ion under the Hubbard model,\nwhereas the hole polaron was dispersed over four oxygen atoms, consistent with\nthe hybrid DFT studies. The anatase electron polarons were dispersed at lower\non-site potentials but were more localized at higher potentials. Both methods\npredict that brookite has a higher driving force for the formation of polarons\nthan anatase."
    },
    {
        "anchor": "Donor Electron Wave Functions for Phosphorus in Silicon: Beyond\n  Effective Mass Theory: We calculate the electronic wave-function for a phosphorus donor in silicon\nby numerical diagonalisation of the donor Hamiltonian in the basis of the pure\ncrystal Bloch functions. The Hamiltonian is calculated at discrete points\nlocalised around the conduction band minima in the reciprocal lattice space.\nSuch a technique goes beyond the approximations inherent in the effective-mass\ntheory, and can be modified to include the effects of altered donor impurity\npotentials, externally applied electro-static potentials, as well as the\neffects of lattice strain. Modification of the donor impurity potential allows\nthe experimentally known low-lying energy spectrum to be reproduced with good\nagreement, as well as the calculation of the donor wavefunction, which can then\nbe used to calculate parameters important to quantum computing applications.",
        "positive": "Magnetism between magnetic adatoms on monolayer NbSe$_2$: In this work, we report on an $ab-initio$ computational study of the\nelectronic and magnetic properties of transition metal adatoms on a monolayer\nof NbSe$_2$. We demonstrate that Cr, Mn, Fe and Co prefer all to sit above the\nNb atom, where the $d$ states experience a substantial hybridization. The\ninter-atomic exchange coupling is shown to have an oscillatory nature\naccompanied by an exponential decay, in accordance with what theory predicts\nfor a damped Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. Our results\nindicate that the qualitative features of the magnetic coupling for the four\ninvestigated adatoms can be connected to the fine details of their Fermi\nsurface. In particular, the oscillations of the exchange in Fe and Co are found\nto be related to a single nesting vector, connecting large electrons and hole\npockets. Most interestingly, this behavior is found to be unaffected by changes\ninduced on the height of the impurity, which makes the magnetism robust to\nexternal perturbations. Considering that NbSe$_2$ is a superconductor down to a\nsingle layer, our research might open the path for further research into the\ninterplay between magnetic and superconducting characteristics, which could\nlead to novel superconductivity engineering."
    },
    {
        "anchor": "Role of lithium intercalation in fluorine-doped tin oxide thin films:\n  Ab-initio calculations and experiment: Using a combination of experimental techniques and density functional theory\n(DFT) calculations, the influence of lithium insertion on the electronic and\nelectrochemical properties of fluourine-doped SnO$_2$ (FTO) is assessed. For\nthis purpose, we investigate the electrochromic behavior of commercial FTO\nelectrode embedded in a solution of lithium perclorate (LiClO$_4$). The\nelectrochromic properties are evaluated by UV-VIS spectroscopy, cyclic\nvoltammetry, and chronoamperometry. These tests show that FTO exhibits\nelectrochromism with a respectable coloration efficiency ($\\eta=47.9$ cm$^2$/C\n@ 637 nm). DFT study indicates that lithium remains ionized in the lattice,\nraising the Fermi level about 0.7 eV deep into the conduction band. X-ray\nphotoelectron spectroscopy (XPS) is used to study chemical bonding and\noxidation states. XPS analysis of the Sn 3d core levels reveals that lithium\ninsertion in FTO induces a shift of 350 meV in the Sn 3d states suggesting that\nlithium is incorporated into the SnO$_2$ lattice.",
        "positive": "Structure of the icosahedral Ti-Zr-Ni quasicrystal: The atomic structure of the icosahedral Ti-Zr-Ni quasicrystal is determined\nby invoking similarities to periodic crystalline phases, diffraction data and\nthe results from ab initio calculations. The structure is modeled by\ndecorations of the canonical cell tiling geometry. The initial decoration model\nis based on the structure of the Frank-Kasper phase W-TiZrNi, the 1/1\napproximant structure of the quasicrystal. The decoration model is optimized\nusing a new method of structural analysis combining a least-squares refinement\nof diffraction data with results from ab initio calculations. The resulting\nstructural model of icosahedral Ti-Zr-Ni is interpreted as a simple decoration\nrule and structural details are discussed."
    },
    {
        "anchor": "Topological interfacial states in ferroelectric domain walls of\n  two-dimensional bismuth: Using machine learning method, we investigate various domain walls for the\nrecently discovered single-element ferroelectrics bismuth monolayer [Nature\n617, 67 (2023)]. Surprisingly, we find that the charged domain wall\nconfiguration has a lower energy than the uncharged domain wall structure due\nto its low electrostatic repulsion potential. Two stable charged domain wall\nconfigurations exhibit topological interfacial states near their domain walls,\nwhich is caused by the change of the Z_2 number between ferroelectric and\nparaelectric states. Interestingly, different from the edge states of\ntopological insulators, the topological interfacial states related Dirac bands\nare contributed from different edges which is caused by the build-in electric\nfield of FE. Our works thus indicate that domain walls in two-dimensional\nbismuth can be a good platform for ferroelectric domain wall devices.",
        "positive": "Scandium decorated C$_{24}$ fullerene as high capacity reversible\n  hydrogen storage material: Insights from density functional theory\n  simulations: Using first-principles density functional theory simulations, we have\nobserved that the scandium decorated C$_{24}$ fullerene can adsorb up to six\nhydrogen molecules with an average adsorption energy of -0.35 eV per H$_2$ and\naverage desorption temperature of 451 K. The gravimetric wt % of hydrogen for\nthe scandium decorated C$_{24}$ fullerene system is 13.02%, which is\nsufficiently higher than the Department of Energy, United States demand.\nElectronic structure, orbital interactions, and charge transfer mechanisms are\nexplained using the density of states, spatial charge density difference plots,\nand Bader charge analysis. A total amount of 1.44e charge transfer from the 3d\nand 4s orbitals of scandium to the 2p carbon orbitals of C$_{24}$ fullerene.\nHydrogen molecules are attached to scandium decorated C$_{24}$ fullerene by\nKubas type of interactions. Diffusion energy barrier calculations predict that\nthe existence of a sufficient energy barrier will prevent metal-metal\nclustering. Ab-initio molecular dynamics (A.I.M.D.) simulations confirm the\nsolidity of the structure at the highest desorption temperature. Therefore, we\nbelieve that the scandium decorated C$_{24}$ fullerene system is a\nthermodynamically stable, promising reversible high-capacity hydrogen storage\ndevice."
    },
    {
        "anchor": "Single crystal studies and electronic structure investigation of a\n  room-temperature semiconductor NaMnAs: We report synthesis of single crystalline NaMnAs, confirm its\nantiferromagnetic order and characterise the sample by photoemission\nspectroscopy. The electronic structure was studied using optical transmittance,\nx-ray and ultraviolet spectroscopy and by theoretical modeling using local\ndensity approximation (LDA) extended to LDA+U when Heisenberg model parameters\nwere determined. Optical transmittance measurement have confirmed the\ntheoretical predictions that NaMnAs is a semiconductor. Also the N\\'eel\ntemperature was closer determined for the first time from temperature\ndependence of magnetization, in agreement with our Monte Carlo simulations.",
        "positive": "Nonlinear Decay of Quantum Confined Magnons in Itinerant Ferromagnets: Quantum confinement leads to the emergence of several magnon modes in\nultrathin layered magnetic structures. We probe the lifetime of these quantum\nconfined modes in a model system composed of three atomic layers of Co grown on\ndifferent surfaces. We demonstrate that the quantum confined magnons exhibit\nnonlinear decay rates, which strongly depend on the mode number, in sharp\ncontrast to what is assumed in the classical dynamics. Combining the\nexperimental results with those of linear-response density functional\ncalculations we provide a quantitative explanation for this nonlinear damping\neffect. The results provide new insights into the decay mechanism of spin\nexcitations in ultrathin films and multilayers and pave the way for tuning the\ndynamical properties of such structures."
    },
    {
        "anchor": "Magneto-optical and magnetotransport properties of heavily Mn-doped\n  GaMnAs: We have studied the magneto-optical and magnetotrasnport properties of GaMnAs\nthin films with high Mn concentrations (x= 12.2 - 21.3%) grown by\nmolecular-beam epitaxy. These heavily Mn-doped GaMnAs films were formed by\ndecreasing the growth temperature to as low as 150-190 degree C and by reducing\nthe film thickness to 10 nm in order to prevent precipitation of hexagonal MnAs\nclusters. Magnetic circular dichroism (MCD) and anomalous Hall effect\nmeasurements indicate that these GaMnAs films have the nature of intrinsic\nferromagnetic semiconductors with high ferromagnetic transition temperature up\nto 170 K.",
        "positive": "Direct imaging of antiferromagnetic domains in Mn$_2$Au manipulated by\n  high magnetic fields: In the field of antiferromagnetic (AFM) spintronics, information about the\nN\\'eel vector, AFM domain sizes, and spin-flop fields is a prerequisite for\ndevice applications but is not available easily. We have investigated AFM\ndomains and spin-flop induced changes of domain patterns in Mn2Au(001)\nepitaxial thin films by X-ray magnetic linear dichroism photoemission electron\nmicroscopy (XMLD-PEEM) using magnetic fields up to 70 T. As-prepared Mn$_2$Au\nfilms exhibit AFM domains with an average size $\\sim$ 1 $\\mu$m. Application of\na 30T field, exceeding the spin-flop field, along a magnetocrystalline easy\naxis, dramatically increases the AFM domain size with N\\'eel vectors\nperpendicular to the applied field direction. The width of N\\'eel type domain\nwalls (DW) is below the spatial resolution of the PEEM and therefore can only\nbe estimated from an analysis of the DW profile to be smaller than 80 nm.\nFurthermore, using the values for the DW width and the spin-flop field, we\nevaluate an in-plane anisotropy constant ranging between 1 and 17 $\\mu$eV/f.u."
    },
    {
        "anchor": "Physics-based material parameters extraction from perovskite experiments\n  via Gaussian process: The ability to extract material parameters of perovskite from quantitative\nexperimental analysis is essential for rational design of photovoltaic and\noptoelectronic applications. However, the difficulty of this analysis increases\nsignificantly with the complexity of the theoretical model and the number of\nmaterial parameters for perovskite. Here we use Gaussian process to develop an\nanalysis platform that can extract up to 8 fundamental material parameters of\nan organometallic perovskite semiconductor from a transient photoluminescence\nexperiment, based on a complex full physics model that includes drift-diffusion\nof carriers and dynamic defect occupation. An example study of thermal\ndegradation reveals that changes in doping concentration and carrier mobility\ndominate, while the defect energy level remains nearly unchanged. This platform\ncan be conveniently applied to other experiments or to combinations of\nexperiments, accelerating materials discovery and optimization of semiconductor\nmaterials for photovoltaics and other applications.",
        "positive": "Oxidation Resistant Germanium Nanowires: Bulk Synthesis, Long Chain\n  Alkanethiol Functionalization and Langmuir-Blodgett Assembly: A simple method is developed to synthesize gram quantities of uniform Ge\nnanowires (GeNWs) by chemical vapor deposition on preformed, monodispersed\nseed-particles loaded onto high surface area silica support. Various chemical\nfunctionalization schemes are investigated to passivate the GeNW surfaces using\nalkanethiols and alkyl Grignard reactions. The stability of functionalization\nagainst oxidation of germanium for various alkyl chain lengths is elucidated by\nX-ray photoelectron spectroscopy. Among all schemes tested, long chain\nalkanethiols (>=C12) are found to impart the most stable GeNW passivation\nagainst oxidation upon extended exposure to ambient air. Further, the\nchemically functionalized oxidation-resistant nanowires are soluble in organic\nsolvents and can be readily assembled into close-packed Langmuir-Blodgett films\npotentially useful for future high performance electronic devices."
    },
    {
        "anchor": "Effect of Bi Substitution on Thermoelectric Properties of SbSe2-based\n  Layered Compounds NdO$_{0.8}$F$_{0.2}$Sb$_{1-x}$Bi$_x$Se$_2$: Although SbSe2-based layered compounds have been predicted to be\nhigh-performance thermoelectric materials and topological materials, most of\nthese compounds obtained experimentally have been insulators so far. Here, we\npresent the effect of Bi substitution on the thermoelectric properties of\nSbSe2-based layered compounds NdO0.8F0.2Sb1-xBixSe2 (x = 0-0.4). The room\ntemperature electrical resistivity is decreased to 8.0 * 10^-5 ohmm for x =\n0.4. The electrical power factor is calculated to be 1.4 * 10^-4 W/mK^2 at 660\nK, which is in reasonable agreement with combined Jonker and Ioffe analysis.\nThe room-temperature lattice thermal conductivity of less than 1 W/mK is almost\nindependent of x, in contrast to the point-defect scattering model for\nconventional alloys. The present work provides an avenue for exploring\nSbSe2-based insulating and BiSe2-based conducting systems.",
        "positive": "Growth of High-Mobility Bi2Te2Se Nanoplatelets on hBN Sheets by van der\n  Waals Epitaxy: The electrical detection of the surface states of topological insulators is\nstrongly impeded by the interference of bulk conduction, which commonly arises\ndue to pronounced doping associated with the formation of lattice defects. As\nexemplified by the topological insulator Bi2Te2Se, we show that via van der\nWaals epitaxial growth on thin hBN substrates the structural quality of such\nnanoplatelets can be substantially improved. The surface state carrier mobility\nof nanoplatelets on hBN is increased by a factor of about 3 compared to\nplatelets on conventional Si/SiOx substrates, which enables the observation of\nwell-developed Shubnikov-de Haas oscillations. We furthermore demonstrate the\npossibility to effectively tune the Fermi level position in the films with the\naid of a back gate."
    },
    {
        "anchor": "Efficient core-excited state orbital perspective on calculating X-ray\n  absorption transitions in determinant framework: X-ray absorption spectroscopy (XAS) is an explicit probe of the unoccupied\nelectronic structure of materials and an invaluable tool for fingerprinting\nvarious electronic properties and phenomena. Computational methods capable of\nsimulating and analysing such spectra are therefore in high demand for\ncomplementing the experimental results and for extracting valuable insights\ntherefrom. In particular, a recently proposed first-principles approach titled\nMany-Body XAS (MBXAS), which approximates the final (initial) state as a Slater\ndeterminant constructed from Kohn-Sham (KS) orbitals optimized in absence\n(presence) of the relevant core-hole has shown promising prospects in\nevaluating the transition amplitudes. In this article, we show that the MBXAS\napproach can be rederived using a transition operator expressed entirely in the\nbasis of core-excited state KS orbitals and that this reformulation offers\nsubstantial practical and conceptual advantages. In addition to circumventing\nprevious issues of convergence with respect to the number of unoccupied\nground-state orbitals, the aforementioned representation reduces the\ncomputational expense by rendering the calculation of such orbitals unnecessary\naltogether. The reformulated approach also provides a direct pathway for\ncomparing the many-body approximation with the so-called single-particle\ntreatment and indicates the relative importance in observed XAS intensity of\nthe relaxation of the valence occupied subspace induced by the core excitation.\nFinally, using the core-excited state basis, we define auxiliary orbitals for\nx-ray absorption and demonstrate their utility in explaining the spectral\nintensity by contrasting them with single-particle approximations to the\nexcited state.",
        "positive": "Quantifying Charge Extraction and Recombination Using the Rise and Decay\n  of the Transient Photovoltage of Perovskite Solar Cells: The extraction of photogenerated charge carriers and the generation of a\nphotovoltage belong to the fundamental functionalities of any solar cell. These\nprocesses happen not instantaneously but rather come with finite time\nconstants, e.g., a time constant related to the rise of the externally measured\nopen circuit voltage following a short light pulse. The present paper provides\na new method to analyze transient photovoltage measurements at different bias\nlight intensities combining rise and decay times of the photovoltage. The\napproach uses a linearized version of a system of two coupled differential\nequations that is solved analytically be determining the eigenvalues of a 2 x 2\nmatrix. By comparison between the eigenvalues and the measured rise and decay\ntimes during a transient photovoltage measurement, we determine the rates of\ncarrier recombination and extraction as a function of bias voltage and\nestablish a simple link between their ratio and the efficiency losses in the\nperovskite solar cell."
    },
    {
        "anchor": "First Principles Theory of the Pressure Induced Invar Effect in FeNi\n  Alloys: The Fe$_{0.64}$Ni$_{0.36}$ alloy exhibits an anomalously low thermal\nexpansion at ambient conditions, an effect that is known as the invar effect.\nOther Fe$_{x}$Ni$_{1-x}$ alloys do not exhibit this effect at ambient\nconditions but upon application of pressure even Ni-rich compositions show low\nthermal expansion, thus called the pressure induced invar effect. We\ninvestigate the pressure induced invar effect for Fe$_{x}$Ni$_{1-x}$ for x =\n0.64, 0.50, 0.25 by performing a large set of supercell calculations, taking\ninto account noncollinear magnetic states. We observe anomalies in the equation\nof states for the three compositions. The anomalies coincide with magnetic\ntransitions from a ferromagnetic state at high volumes to a complex magnetic\nstate at lower volumes. Our results can be interpreted in the model of\nnoncollinear magnetism which relates the invar effect to increasing\ncontribution of magnetic entropy with pressure.",
        "positive": "Effect of quantization of vibrations on the structural properties of\n  crystals: We study the structural effects produced by the quantization of vibrational\ndegrees of freedom in periodic crystals at zero temperature. To this end we\nintroduce a methodology based on mapping a suitable subspace of the vibrational\nmanifold and solving the Schroedinger equation in it. A number of increasingly\naccurate approximations ranging from the quasi-harmonic approximation (QHA) to\nthe vibrational self-consistent field (VSCF) method and the exact solution are\ndescribed. A thorough analysis of the approximations is presented for model\nmonoatomic and hydrogen-bonded chains, and results are presented for a linear\nHF chain where the potential energy surface is obtained via first-principles\nelectronic structure calculations. We focus on quantum nuclear effects on the\nlattice constant, and show that the VSCF is an excellent approximation, meaning\nthat correlation between modes is not extremely important. The QHA is excellent\nfor covalently-bonded, mildly anharmonic systems, but it fails for\nhydrogen-bonded ones. In the latter, the zero-point energy exhibits a\nnon-analytic behavior at the lattice constant where the H-atoms center, which\nleads to a spurious secondary minimum in the quantum-corrected energy curve. An\ninexpensive anharmonic appoximation of non-interacting modes appears to produce\nrather good results for hydrogen-bonded chains, for small system sizes.\nHowever, it converges to the incorrect QHA results for increasing size. Isotope\neffects are studied for the first-principles HF chain. We show how the lattice\nconstant and the HF distance increase with decreasing mass, and how the QHA\nproves to be insufficient to reproduce this behavior."
    },
    {
        "anchor": "Dynamic Electrophysical Characterization of Porous Silicon based\n  Humidity Sensitive Elements: The results of the investigation of changes of parameters of dynamic bipolar\ncharge-voltage and bipolar and unipolar dynamic current-voltage characteristics\nand transient currents connected with the pulse change of humidity for the\nsamples of por-Si are presented. The view of high voltage current-voltage\ncurves is characteristic for poling processes in the space charge region\nsimilar to that observed in the case of typical ionic conductors. Observed\nphases of transformation of investigated electrophysical characteristics\nreflect the time scale of processes in the consequence adsorption-dissociation\nand transfer - desorption. The efficiency of using the methods of dynamic\nelectrophysical characterization for studying characteristics of porous\nmaterials under fast humidity changes was demonstrated.",
        "positive": "Optical properties of BAlN and BGaN for applications in latticematched\n  UV optical structures: The optical properties of BAlN and BGaN ternary alloys are investigated using\nfirst-principle calculation. Hybrid density functional theory is applied to\ndetermine the refractive indices of different alloys. A peculiar non-linear\nbehavior of the static refractive index as a function of boron composition is\nfound. The results of this calculation are interpolated to generate a three\ndimensional dataset, which could be used for designing a myriad of strained and\nstrain-free optoelectronic and photonic devices. This is then used to find a\nlattice-matched heterostructure optimized for DBR applications\n(B0.108Ga0.892N/AlN). A DBR design with 25 pairs at a wavelength of 375 nm is\nfound to have peak reflectivity of 99.8% and a bandwidth of 26 nm."
    },
    {
        "anchor": "Multiple ferroelectric nematic phases of a highly polar liquid crystal\n  compound: Ferroelectric nematic liquid crystals represent not only interesting\nfundamental science, but they also hold promise for storage capacitors with\nhigh power density or new information display technology having sub-millisecond\nswitching. In this work we describe the synthesis and measurements of the\nphysical properties of a new highly polar ferroelectric nematic compound,\n4-nitrophenyl 4-[(2,4-dimethoxylbenzoyl)oxy]-2-fluorobenzoate (RT11001). The\ndipole moment of this material (along the long molecular axis) is calculated to\nexceed 11.5 Debye. We employ a wide range of physical characterization methods\nincluding differential scanning calorimetry (DSC), mass density measurement,\noptical birefringence, polarizing optical microscopy (POM), electric current\nanalysis, and electro-optical switching, to show that RT11001 has three\ndistinct ferroelectric states, F1, F2 and F3. F1 is purely orientationally\nordered ferroelectric nematic phase (NF), F2 has a ferroelectric nematic with\npossibly short-range hexagonal order normal to the director (NhF), and we\nconjecture that F3 has a long-range hexagonal order normal to the director\n(ColhF).",
        "positive": "Molecular Beam Epitaxy of GaN Nanowires on Epitaxial Graphene: We demonstrate an all-epitaxial and scalable growth approach to fabricate\nsingle-crystalline GaN nanowires on graphene by plasma-assisted molecular beam\nepitaxy. As substrate, we explore several types of epitaxial graphene layer\nstructures synthesized on SiC. The different structures differ mainly in their\ntotal number of graphene layers. Because graphene is found to be etched under\nactive N exposure, the direct growth of GaN nanowires on graphene is only\nachieved on multilayer graphene structures. The analysis of the nanowire\nensembles prepared on multilayer graphene by Raman spectroscopy and\ntransmission electron microscopy reveals the presence of graphene underneath as\nwell as in between nanowires, as desired for the use of this material as\ncontact layer in nanowire-based devices. The nanowires nucleate preferentially\nat step edges, are vertical, well aligned, epitaxial, and of comparable\nstructural quality as similar structures fabricated on conventional substrates."
    },
    {
        "anchor": "First-principle study on compensated half metallic double perovskite\n  compound $Ba_2PrVO_6$: The first-principle study on double perovskite compound Ba$_2$PrVO$_6$ has\nbeen presented in this paper. By analysing band structures and integrated\ndensity of states, it is found that Ba$_2$PrVO$_6$ is ferromagnetic metallic\nwithin LSDA and compensated half metallic whithin LSDA+U. According to the\ntotal and partial density of states, the anti-ferromagnetism of Ba$_2$PrVO$_6$\nis originated from the spin down state Pr$^{4+}$ ($4f_{-2}$) and the spin up\nhybridized state between the partially filled $t_{2g}$ state of V and the\npartially filled triple-degeneration state $4f_{-1}$, $4f_{+1}$, $4f_{+3}$ of\nPr. We have investigated the magnetic evaluation of Ba$_2$PrVO$_6$ through\nfixed spin moment calculations, and the results indicate that the compensated\nhalf-metallic state is the ground state. The thermodynamic properties of\nBa$_2$PrVO$_6$ are also studied by employing the quasi-harmonic Debye model.",
        "positive": "Defect evolution and interplay in n-type InN: The nature and interplay of intrinsic point and extended defects in n-type\nSi-doped InN epilayers with free carrier concentrations up to 6.6x10E20cm-3 are\nstudied using positron annihilation spectroscopy and transmission electron\nmicroscopy and compared to results from undoped irradiated films. In as-grown\nSi-doped samples, V_In-V_N complexes are the dominant III-sublattice related\nvacancy defects. Enhanced formation of larger V_In-mV_N clusters is observed at\nthe interface, which speaks for high concentrations of additional V_N in the\nnear-interface region and coincides with an increase in the density of screw\nand edge type dislocations in that area."
    },
    {
        "anchor": "Measurement of g-factor tensor in a quantum dot and disentanglement of\n  exciton spins: We perform polarization-resolved magneto-optical measurements on single InAsP\nquantum dots embedded in an InP nanowire. In order to determine all elements of\nthe electron and hole $g$-factor tensors, we measure in magnetic field with\ndifferent orientations. The results of these measurements are in good agreement\nwith a model based on exchange terms and Zeeman interaction. In our experiment,\npolarization analysis delivers a powerful tool that not only significantly\nincreases the precision of the measurements, but also enables us to probe the\nexciton spin state evolution in magnetic fields. We propose a disentangling\nscheme of heavy-hole exciton spins enabling a measurement of the electron spin\n$T_2$ time.",
        "positive": "Band Alignment of 2D Semiconductors for Designing Heterostructures with\n  Momentum Space Matching: We present a comprehensive study of the band alignments of two-dimensional\n(2D) semiconducting materials and highlight the possibilities of forming\nmomentum-matched type I, II and III heterojunctions; an enticing possibility\nbeing atomic heterostructures where the constituent monolayers have band edges\nat the zone center. Our study, which includes the Group IV and III-V compound\nmonolayer materials, Group V elemental monolayer materials, transition metal\ndichalcogenides (TMD) and transition metal trichalcogenides (TMT) reveals that\nalmost half of these materials have conduction and/or valence band edges\nresiding at the zone center. Using first-principles density functional\ncalculations, we present the type of the heterojunction for 903 different\npossible combination of these 2D materials which establishes a periodic table\nof heterojunctions."
    },
    {
        "anchor": "First-principles study of a single-molecule magnet Mn_{12} monolayer on\n  the Au(111) surface: The electronic structure of a monolayer of single-molecule magnets Mn$_{12}$\non a Au(111) surface is studied using spin-polarized density-functional theory.\nThe Mn$_{12}$ molecules are oriented such that the magnetic easy axis is normal\nto the surface, and the terminating ligands in the Mn$_{12}$ are replaced by\nthiol groups (-SH) where the H atoms are lost upon adsorption onto the surface.\nThis sulfur-terminated Mn$_{12}$ molecule has a total magnetic moment of 18\n$\\mu_B$ in the ground state, in contrast to 20$\\mu_B$ for the standard\nMn$_{12}$. The Mn$_{12}$ molecular orbitals broaden due to the interaction of\nthe molecule with the gold surface and the broadening is of the order of 0.1\neV. It is an order of magnitude less than the single-electron charging energy\nof the molecule so the molecule is weakly bonded to the surface. Only electrons\nwith majority spin can be transferred from the surface to the sulfur-terminated\nMn$_{12}$ since the gold Fermi level is well above the majority lowest\nunoccupied molecular orbital (LUMO) but below the minority LUMO. The amount of\nthe charge transfer is calculated to be 1.23 electrons, dominated by the tail\nin the electronic distribution of the gold surface. A calculation of level\nshift upon charging provides 0.28 electrons being transferred. The majority of\nthe charge transfer occurs at the S, C, and O atoms close to the surface. The\ntotal magnetic moment also changes from 18 $\\mu_B$ to 20 $\\mu_B$, due to\nrearrangements of the magnetic moments on the S and Mn atoms upon adsorption\nonto the surface. The magnetic anisotropy barrier is computed including\nspin-orbit interaction self-consistently in density-functional theory. The\nbarrier for the Mn$_{12}$ on the gold surface decreases by 6 K in comparison to\nthat for an isolated Mn$_{12}$ molecule.",
        "positive": "Fabrication of yttrium-iron-garnet/Pt multilayers for the longitudinal\n  spin Seebeck effect: For longitudinal spin Seebeck effect (LSSE) devices, a multilayer structure\ncomprising ferromagnetic and nonmagnetic layers is expected to improve their\nthermoelectric power. In this study, we developed the fabrication method for\nalternately stacked yttrium-iron-garnet (YIG)/Pt multilayer films on a\ngadolinium gallium garnet (GGG) (110) substrate, GGG/[YIG(49 nm)/Pt(4 nm)]$_n$\n($n =$ 1 - 5) based on room-temperature sputtering and $ex$-$situ$\npost-annealing method and we evaluated their structural and LSSE properties.\nThe fabricated [YIG/Pt]$_n$ samples show flat YIG/Pt interfaces and almost\nidentical saturation magnetization $M_{\\rm s}$, although they contain\npolycrystalline YIG layers on Pt layers as well as single-crystalline YIG\nlayers on GGG. In the samples, we observed clear LSSE signals and found that\nthe LSSE thermoelectric power factor (PF) increases monotonically with\nincreasing $n$; the PF of the [YIG/Pt]$_5$ sample is enhanced by a factor of\n$\\sim 28$ compared to that of [YIG/Pt]$_1$. This work may provide a guideline\nfor developing future multilayerbased LSSE devices."
    },
    {
        "anchor": "Observation of spin Seebeck contribution to the transverse thermopower\n  in Ni-Pt and MnBi-Au bulk nanocomposites: Transverse thermoelectric devices produce electric fields perpendicular to an\nincident heat flux. Classically, this process is driven by the Nernst effect in\nbulk solids, wherein a magnetic field generates a Lorentz force on thermally\nexcited electrons. The spin Seebeck effect (SSE) also produces\nmagnetization-dependent transverse electric fields. SSE is traditionally\nobserved in thin metallic films deposited on electrically insulating\nferromagnets, but the films' high resistance limits thermoelectric conversion\nefficiency. Combining Nernst and SSE in bulk materials would enable devices\nwith simultaneously large transverse thermopower and low electrical resistance.\nHere we demonstrate experimentally this is possible in composites of conducting\nferromagnets (Ni or MnBi) containing metallic nanoparticles with strong\nspin-orbit interactions (Pt or Au). These materials display positive shifts in\ntransverse thermopower attributable to inverse spin Hall electric fields in the\nnanoparticles. This more than doubles the power output of the Ni-Pt materials,\nestablishing proof-of-principle that SSE persists in bulk nanocomposites.",
        "positive": "A Basic Thermodynamic Derivation of the Maximum Overburden Pressure\n  Generated in Frost Heave: I describe a simple heat-engine derivation of the maximum overburden pressure\nthat can be generated in frost heave. The method stems from the fact that\nuseful work can, in principle, be extracted from the forces generated by an\nadvancing solidification front via the frost heave mechanism. Using an\nidealized frost heave engine, together with the maximum thermodynamic\nefficiency of any heat engine, one can derive the maximum overburden pressure.\nA similar argument can also produce the maximum thermodynamic buoyancy force on\na foreign object within a solid surrounded by a premelted layer."
    },
    {
        "anchor": "Optically bright $p$-excitons indicating strong Coulomb coupling in\n  transition-metal dichalcogenides: It is shown that the strong Coulomb coupling in intrinsic suspended\nsemiconducting transition metal dichalcogenides can exceed the critical value\nneeded for an excitonic ground state. The dipole-allowed optical excitations\nthen correspond to intra-excitonic transitions such that the optically bright\nexcitonic transitions near the Dirac points have a $p$-like symmetry whereas\nthe $s$-like states are dipole forbidden. The large intrinsic coupling strength\nseems to be a generic property of the semiconducting transition metal\ndichalcogenides and strong Coulomb-coupling signatures in the form of the\noptical selection rules can be observed even in samples grown on typical\nsubstrates like SiO$_2$. For the examples of WS$_2$ and WSe$_2$, excellent\nagreement of the computed excitonic resonance energies with recent experiments\nis demonstrated.",
        "positive": "The correlation energy functional within the GW-RPA approximation: exact\n  forms, approximate forms and challenges: In principle, the Luttinger-Ward Green's function formalism allows one to\ncompute simultaneously the total energy and the quasiparticle band structure of\na many-body electronic system from first principles. We present approximate and\nexact expressions for the correlation energy within the GW-RPA approximation\nthat are more amenable to computation and allow for developing efficient\napproximations to the self-energy operator and correlation energy. The exact\nform is a sum over differences between plasmon and interband energies. The\napproximate forms are based on summing over screened interband transitions. We\nalso demonstrate that blind extremization of such functionals leads to\nunphysical results: imposing physical constraints on the allowed solutions\n(Green's functions) is necessary. Finally, we present some relevant numerical\nresults for atomic systems."
    },
    {
        "anchor": "Strain induced lithium functionalized graphane as a high capacity\n  hydrogen storage material: Strain effects on the stability, electronic structure, and hydrogen storage\ncapacity of lithium-doped graphane (CHLi) have been investigated by stateof-the\nart first principle density functional theory (DFT). Molecular dynamics MD)\nsimulations have confirmed the stability of Li on graphane sheet when it is\nsubject to 10% of tensile strain. Under biaxial asymmetric strain, the binding\nenergy of Li of graphane (CH) sheet increases by 52% with respect to its bulk's\ncohesive energy. With 25% doping concentration of Li on CH sheet,the\ngravimetric density of hydrogen storage is found to reach up to 12.12wt%. The\nadsorption energies of H2 are found to be within the range of practical H2\nstorage applications.",
        "positive": "High Curie temperatures in ferromagnetic Cr-doped AlN thin films: Al1-xCrxN thin films with $0.02\\le x \\le 0.1$ were deposited by reactive\nco-sputtering onto c-plane (001) sapphire. Room-temperature ferromagnetism with\na coercive field of 85 Oe was observed in samples with chromium contents as low\nas x = 0.027 (2.7%). With increasing Cr content the mean magnetic moment is\nstrongly suppressed, with a maximum saturation moment of 0.62 and 0.71 $\\mu_B$\nper Cr atom at 300 and 50 K respectively. We show that the Curie temperature of\nAl1-xCrxN for x = 0.027 is greater than 900 K."
    },
    {
        "anchor": "Point defect concentrations in metastable Fe-C alloys: Point defect species and concentrations in metastable Fe-C alloys are\ndetermined using density functional theory and a constrained free-energy\nfunctional. Carbon interstitials dominate unless iron vacancies are in\nsignificant excess, whereas excess carbon causes greatly enhances vacancy\nconcentration. Our predictions are amenable to experimental verification; they\nprovide a baseline for rationalizing complex microstructures known in hardened\nand tempered steels, and by extension other technological materials created by\nor subjected to extreme environments.",
        "positive": "Fermi level pinning at the Ge(001) surface - A case for non-standard\n  explanation: To explore the origin of the Fermi level pinning in germanium we investigate\nthe Ge(001) and Ge(001):H surfaces. The absence of relevant surface states in\nthe case of Ge(001):H should unpin the surface Fermi level. This is not\nobserved. For samples with donors as majority dopants the surface Fermi level\nappears close to the top of the valence band regardless of the surface\nstructure. Surprisingly, for the passivated surface it is located below the top\nof the valence band allowing scanning tunneling microscopy imaging within the\nband gap. We argue that the well known electronic mechanism behind band bending\ndoes not apply and a more complicated scenario involving ionic degrees of\nfreedom is therefore necessary. Experimental techniques involve four point\nprobe electric current measurements, scanning tunneling microscopy and\nspectroscopy."
    },
    {
        "anchor": "Exciton tuning in monolayer WSe$_2$ via substrate induced electron\n  doping: We report on large exciton tuning in WSe$_2$ monolayers via substrate induced\nnon-degenerate doping. We observe a redshift of $\\sim$62 meV for the $A$\nexciton together with a 1-2 orders of magnitude photoluminescence (PL)\nquenching when the monolayer WSe$_2$ is brought in contact with highly oriented\npyrolytic graphite (HOPG) compared to the dielectric substrates such as hBN and\nSiO$_2$. As the evidence of doping from HOPG to WSe$_2$, a drastic increase of\nthe trion emission intensity was observed. Using a systematic PL and Kelvin\nprobe force microscopy (KPFM) investigation on WSe$_2$/HOPG, WSe$_2$/hBN, and\nWSe$_2$/graphene, we conclude that this unique excitonic behavior is induced by\nelectron doping from the substrate. Our results propose a simple yet efficient\nway for exciton tuning in monolayer WSe$_2$, which plays a central role in the\nfundamental understanding and further device development.",
        "positive": "Extremely High Thermal Conductivity of Graphene: Experimental Study: We report on the first measurement of the thermal conductivity of a suspended\nsingle layer graphene. The measurements were performed using a non-contact\noptical technique. The near room-temperature values of the thermal conductivity\nin the range ~ 4840 to 5300 W/mK were extracted for a single-layer graphene.\nThe extremely high value of the thermal conductivity suggests that graphene can\noutperform carbon nanotubes in heat conduction."
    },
    {
        "anchor": "Defect-induced magnetism in graphite through neutron irradiation: We have investigated the variation in the magnetization of highly ordered\npyrolytic graphite (HOPG) after neutron irradiation, which introduces defects\nin the bulk sample and consequently gives rise to a large magnetic signal. We\nobserve strong paramagnetism in HOPG, increasing with the neutron fluence. We\ncorrelate the induced paramagnetism with structural defects by comparison with\ndensity-functional theory calculations. In addition to the in-plane vacancies,\nthe trans-planar defects also contribute to the magnetization. The lack of any\nmagnetic order between the local moments is possibly due to the absence of\nhydrogen/nitrogen chemisorption, or the magnetic order cannot be established at\nall in the bulk form.",
        "positive": "Electro-optic properties of ZrO2, HfO2 and LiNbO3 ferroelectric phases:\n  A comprehensive and comparative study with density functional theory: We report the Pockels electro-optic properties of ZrO2 and HfO2 orthorhombic\nPbc21 and rhombohedral R3m ferroelectric phases, and we compare them to the\nwell-known LiNbO3 Pockels material from density functional theory calculations\nusing the CRYSTAL suite of programs. Specifically, three essential processes\nare explicitly investigated: The electronic, the ionic (or vibrational), and\nthe piezoelectric contributions. Our calculations reveal that the ionic part\ncoming from the low frequency phonon modes contributes the most to the\nelectro-optic coefficients of rhombohedral LiNbO3 and of orthorhombic ZrO2 and\nHfO2. While these low-frequency modes show zero contribution to Pockels\ncoefficients for the rhombohedral phase of the latter compounds."
    },
    {
        "anchor": "Molecular Dynamics Simulation of Ga Penetration along Grain Boundaries\n  in Al: a Dislocation Climb Mechanism: Many systems where a liquid metal is in contact with a polycrystalline solid\nexhibit deep liquid grooves where the grain boundary meets the solid-liquid\ninterface. For example, liquid Ga quickly penetrates deep into grain boundaries\nin Al, leading to intergranular fracture under very small stresses. We report\non a series of molecular dynamics simulations of liquid Ga in contact with an\nAl bicrystal. We identify the mechanism for liquid metal embrittlement, develop\na new model for it, and show that is in excellent agreement with both\nsimulation and experimental data.",
        "positive": "Sublattice spin reversal and field induced $Fe^{3+}$ spin-canting across\n  the magnetic compensation temperature in $Y_{1.5}Gd_{1.5}Fe_{5}O_{12}$\n  rare-earth iron garnet: In the present work $Fe^{3+}$ sublattice spin reversal and $Fe^{3+}$\nspin-canting across the magnetic compensation temperature ($T_{Comp}$) are\ndemonstrated in polycrystalline $Y_{1.5}Gd_{1.5}Fe_{5}O_{12}$ (YGdIG) by means\nof in-field $^{57}Fe$ M$\\ddot{o}$ssbauer spectroscopy measurements.\nCorroborating in-field $^{57}Fe$ M$\\ddot{o}$ssbauer measurements, both\n$Fe^{3+}$ & $Gd^{3+}$ sublattice spin reversal has also been manifested with\nx-ray magnetic circular dichroism (XMCD) measurement in hard x-ray region.\nMoreover from in-field $^{57}Fe$ M$\\ddot{o}$ssbauer measurements, estimation\nand analysis of effective internal hyperfine field ($H_{eff}$), relative\nintensity of absorption lines in a sextet elucidated unambiguously the\nsignatures of $Fe^{3+}$ spin reversal, their continuous transition and field\ninduced spin-canting of $Fe^{3+}$ sublattices across $T_{Comp}$. Further, Fe K-\n(Gd $L_{3}$-) edge XMCD signal is observed to consist of additional spectral\nfeatures, those are identified from $Gd^{3+}$ ($Fe^{3+}$) magnetic ordering,\nenabling us the extraction of both the sublattices ($Fe^{3+}$ & $Gd^{3+}$)\ninformation from a single edge analysis. The evolution of the magnetic moments\nas a function of temperature for both magnetic sublattices extracted either at\nthe Fe K- or Gd $L_3$-edge agree quite well with values that are extracted from\nbulk magnetization data of YGdIG and YIG ($Y_{3}Fe_{5}O_{12}$). These\nmeasurements pave new avenues to investigate how the magnetic behavior of such\ncomplex system acts across the compensation point."
    },
    {
        "anchor": "The Interaction of an 180 degree Ferroelectric Domain Wall with a Biased\n  Scanning Probe Microscopy Tip: Effective Wall Geometry and Thermodynamics in\n  Ginzburg-Landau-Devonshire Theory: The interaction of ferroelectric 180 degree domain wall with a strongly\ninhomogeneous electric field of biased Scanning Probe Microscope tip is\nanalyzed within continuous Landau-Ginzburg-Devonshire theory. Equilibrium shape\nof the initially flat domain wall boundary bends, attracts or repulses from the\nprobe apex, depending on the sign and value of the applied bias. For large\ntip-wall separations, the probe-induced domain nucleation is possible. The\napproximate analytical expressions for the polarization distribution are\nderived using direct variational method. The expressions provide insight how\nthe equilibrium polarization distribution depends on the wall finite-width,\ncorrelation and depolarization effects, electrostatic potential distribution of\nthe probe and ferroelectric material parameters.",
        "positive": "Interplay of instabilities in mounded surface growth: We numerically study a one-dimensional conserved growth equation with\ncompeting linear (Ehrlich-Schwoebel) and nonlinear instabilities. As a control\nparameter is varied, this model exhibits a non-equilibrium phase transition\nbetween two mounded states, one of which exhibits slope selection and the other\ndoes not. The coarsening behavior of mounds in these two phases is studied in\ndetail. In the absence of noise the steady-state configuration depends\ncrucially on which of the two instabilities dominates the early time behavior."
    },
    {
        "anchor": "Microstructure-informed reduced modes synthesized with Wang tiles and\n  the Generalized Finite Element Method: A recently introduced representation by a set of Wang tiles -- a\ngeneralization of the traditional Periodic Unit Cell based approach -- serves\nas a reduced geometrical model for materials with stochastic heterogeneous\nmicrostructure, enabling an efficient synthesis of microstructural\nrealizations. To facilitate macroscopic analyses with a fully resolved\nmicrostructure generated with Wang tiles, we develop a reduced order modelling\nscheme utilizing pre-computed characteristic features of the tiles. In the\noffline phase, inspired by the computational homogenization, we extract\ncontinuous fluctuation fields from the compressed microstructural\nrepresentation as responses to generalized loading represented by the first-\nand second-order macroscopic gradients. In the online phase, using the ansatz\nof the Generalized Finite Element Method, we combine these fields with a coarse\nfinite element discretization to create microstructure-informed reduced modes\nspecific for a given macroscopic problem. Considering a two-dimensional scalar\nelliptic problem, we demonstrate that our scheme delivers less than a 3% error\nin both the relative $L_2$ and energy norms with only 0.01% of the unknowns\nwhen compared to the fully resolved problem. Accuracy can be further improved\nby locally refining the macroscopic discretization and/or employing more\npre-computed fluctuation fields. Finally, unlike the standard snapshot-based\nreduced-order approaches, our scheme handles significant changes in the\nmacroscopic geometry or loading without the need for recalculating the offline\nphase, because the fluctuation fields are extracted without any prior knowledge\non the macroscopic problem.",
        "positive": "Comment on \"Apical charge flux-modulated in-plane transport properties\n  of cuprate superconductors\": The abstract of Phys. Rev. Lett. 121, 157001 (2018) claims to \"demonstrate,\nusing ab initio computations, a new trend suggesting that the cuprates with\nstronger out-of-CuO$_{2}$-plane chemical bonding between the apical anion (O,\nCl) and apical cation (e.g., La, Hg, Bi, Tl) are generally correlated with\nhigher $T_{c\\,\\max}$ in experiments\". We point out that this trend is included\nin the long-known [Phys. Rev. Lett. 87, 047003 (2001)] correlation of\n$T_{c\\,\\max}$ with the hopping range of the electrons at (the most\ninterlayer-bonding sheet of) the Fermi-surface. Contrary to the impression\ngiven in Phys. Rev. Lett. 121, 157001 (2018), the correlation mentioned in\nPhys. Rev. Lett. 87, 047003 (2001) is not simply with the distance, $d_{A},$ of\napical oxygen from the nearest CuO$_{2}$ plane; but rather, as stated in the\nabstract of Phys. Rev. Lett. 87, 047003 (2001), \"It is controlled by the energy\nof the axial orbital, a hybrid between Cu 4$s$, apical-oxygen 2$p_{z},$ and\nfarther orbitals.\""
    },
    {
        "anchor": "Defects, band bending and ionization rings in MoS2: Chalcogen vacancies in transition metal dichalcogenides are widely\nacknowledged as both donor dopants and as a source of disorder. The electronic\nstructure of sulphur vacancies in MoS2 however is still controversial, with\ndiscrepancies in the literature pertaining to the origin of the in-gap features\nobserved via scanning tunneling spectroscopy (STS) on single sulphur vacancies.\nHere we use a combination of scanning tunnelling microscopy (STM) and STS to\nstudy embedded sulphur vacancies in bulk MoS2 crystals. We observe\nspectroscopic features dispersing in real space and in energy, which we\ninterpret as tip position- and bias-dependent ionization of the sulphur vacancy\ndonor due to tip induced band bending (TIBB). The observations indicate that\ncare must be taken in interpreting defect spectra as reflecting in-gap density\nof states, and may explain discrepancies in the literature.",
        "positive": "Self-Supervised Learning and Prediction of Microstructure Evolution with\n  Recurrent Neural Networks: Microstructural evolution is a key aspect of understanding and exploiting the\nstructure-property-performance relation of materials. Modeling microstructure\nevolution usually relies on coarse-grained simulations with evolution\nprinciples described by partial differential equations (PDEs). Here we\ndemonstrate that convolutional recurrent neural networks can learn the\nunderlying physical rules and replace PDE-based simulations in the prediction\nof microstructure phenomena. Neural nets are trained by self-supervised\nlearning with image sequences from simulations of several common processes,\nincluding plane wave propagation, grain growth, spinodal decomposition and\ndendritic crystal growth. The trained networks can accurately predict both\nshort-term local dynamics and long-term statistical properties of\nmicrostructures and is capable of extrapolating beyond the training datasets in\nspatiotemporal domains and configurational and parametric spaces. Such a\ndata-driven approach offers significant advantages over PDE-based simulations\nin time stepping efficiency and offers a useful alternative especially when the\nmaterial parameters or governing PDEs are not well determined."
    },
    {
        "anchor": "A Class of Compounds Featuring Frustrated Triangular Magnetic Lattice\n  CsRESe$_2$ (RE=La-Lu): Quantum Spin-Liquid Candidates: A triangular lattice selenide series of rare earth (RE), CsRESe2, were\nsynthesized as large single crystals using a flux growth method. This series\nstabilized in either trigonal (R-3m) or hexagonal (P63/mmc) crystal systems.\nPhysical properties of CsRESe2 were explored by magnetic susceptibility and\nheat capacity measurements down to 0.4 K. Antiferromagnetic interaction was\nobserved in all magnetic compounds, while no long-range magnetic order was\nfound, indicating the frustrated magnetism. CsDySe2 presents spin freezing at\n0.7 K, revealing a spin-glass state. CsCeSe2 and CsYbSe2 present broad peaks at\n0.7 K and 1.5 K in the magnetization, respectively, suggesting the short-range\ninteractions between magnetic rare earth ions. The lack of signature for\nlong-range magnetic order and spin freezing down to 0.4 K in these compounds\n(RE = Ce, Yb) implies their candidacy for quantum spin liquid state.",
        "positive": "A model for the formation energies of alanates and boranates: We develop a simple model for the formation energies (FEs) of alkali and\nlkaline earth alanates and boranates, based upon ionic bonding between metal\ncations and (AlH4)- or (BH4)- anions. The FEs agree well with values obtained\nfrom first principles calculations and with experimental FEs. The model shows\nthat details of the crystal structure are relatively unimportant. The small\nsize of the (BH4)- anion causes a strong bonding in the crystal, which makes\nboranates more stable than alanates. Smaller alkali or alkaline earth cations\ndo not give an increased FE. They involve a larger ionization potential that\ncompensates for the increased crystal bonding."
    },
    {
        "anchor": "Polarization at the Nanoscale: Modern polarization theory yields surface bound charge associated with\nspontaneous polarization of bulk. However, understanding polarization in nano\nsystems also requires a proper treatment of charge transfer between surface\ndangling bonds. Here, we develop a real-space approach for total polarization\nand apply it to wurtzite semiconductors and BaTiO3 perovskite. First-principles\ncalculations utilizing this approach not only yield spontaneous bulk\npolarization in agreement with Berry phase calculations, but also uncover\nphenomena specific to nano systems. As an example, we show surface passivation\nleads to a complete quenching of the piezoelectric effect, which reemerges only\nat larger length scale and/or spontaneous polarization.",
        "positive": "Graphene physics and insulator-metal transition in compressed hydrogen: Compressed hydrogen passes through a series of layered structures in which\nthe layers can be viewed as distorted graphene sheets. The electronic\nstructures of these layered structures can be understood by studying simple\nmodel systems- an ideal single hydrogen graphene sheet and three-dimensional\nmodel lattices consisting of such sheets. The energetically stable structures\nresult from structural distortions of model graphene-based systems due to\nelectronic instabilities towards Peierls or other distortions associated with\nthe opening of a band gap. Two factors play crucial roles in the metallization\nof compressed hydrogen: (i) crossing of conduction and valence bands in\nhexagonal or graphene-like layers due to topology and (ii) formation of bonding\nstates with $2p_z$ $\\pi$ character."
    },
    {
        "anchor": "Gated Conductance of Thin Indium Tin Oxide - The Simplest Transistor: Transistors are the fundamental building block of modern electronic devices.\nSo far, all transistors are based on various types of semiconductor junctions.\nThe most common bipolar-junction transistors and metal-oxide-semiconductor\nfield-effect transistors contain p-n junctions to control the current,\ndepending on applied biases across the junctions. Thin-film transistors need\nmetal-semiconductor junctions for injecting and extracting electrons from their\nchannels. Here, by coating a heavily-doped thin indium-tin-oxide (ITO) film\nthrough a shadow mask onto a biopolymer chitosan/ITO/glass substrate, we can\nhave a high-performance junctionless transparent organic-inorganic hybrid thin\nfilm transistor. This could be the simplest transistor in the world, to our\nknowledge, not only in its structure, but also its fabrication process. In\naddition, the device performance is found to be greatly enhanced using a\nreinforced chitosan/SiO2 hybrid bilayer dielectric stack. Our results clearly\nshow that this architecture can lead to a new class of low-cost transistors.",
        "positive": "Flexible, Model-Agnostic Method for Materials Data Extraction from Text\n  Using General Purpose Language Models: Accurate and comprehensive material databases extracted from research papers\nare critical for materials science and engineering but require significant\nhuman effort to develop. In this paper we present a simple method of extracting\nmaterials data from full texts of research papers suitable for quickly\ndeveloping modest-sized databases. The method requires minimal to no coding,\nprior knowledge about the extracted property, or model training, and provides\nhigh recall and almost perfect precision in the resultant database. The method\nis fully automated except for one human-assisted step, which typically requires\njust a few hours of human labor. The method builds on top of natural language\nprocessing and large general language models but can work with almost any such\nmodel. The language models GPT-3/3.5, bart and DeBERTaV3 are evaluated here for\ncomparison. We provide a detailed detailed analysis of the methods performance\nin extracting bulk modulus data, obtaining up to 90% precision at 96% recall,\ndepending on the amount of human effort involved. We then demonstrate the\nmethods broader effectiveness by developing a database of critical cooling\nrates for metallic glasses."
    },
    {
        "anchor": "A roadmap for edge computing enabled automated multidimensional\n  transmission electron microscopy: The advent of modern, high-speed electron detectors has made the collection\nof multidimensional hyperspectral transmission electron microscopy datasets,\nsuch as 4D-STEM, a routine. However, many microscopists find such experiments\ndaunting since such datasets' analysis, collection, long-term storage, and\nnetworking remain challenging. Some common issues are the large and unwieldy\nsize of the said datasets, often running into several gigabytes,\nnon-standardized data analysis routines, and a lack of clarity about the\ncomputing and network resources needed to utilize the electron microscope\nfully. However, the existing computing and networking bottlenecks introduce\nsignificant penalties in each step of these experiments, and thus, real-time\nanalysis-driven automated experimentation for multidimensional TEM is\nexceptionally challenging. One solution is integrating microscopy with edge\ncomputing, where moderately powerful computational hardware performs the\npreliminary analysis before handing off the heavier computation to HPC systems.\nIn this perspective, we trace the roots of computation in modern electron\nmicroscopy, demonstrate deep learning experiments running on an edge system,\nand discuss the networking requirements for tying together microscopes, edge\ncomputers, and HPC systems.",
        "positive": "Ab initio insights into the interaction mechanisms between H$_2$,\n  H$_2$O, and O$_2$ molecules with diamond surfaces: Diamond displays outstanding chemical, physical, and tribological properties,\nmaking it attractive for numerous applications ranging from biomedicine to\ntribology. However, the reaction of the materials with molecules present in the\nair, such as oxygen, hydrogen, and water, could significantly change the\nelectronic and tribological properties of the films. In this study, we\nperformed several density functional theory calculations to construct a\ndatabase for the adsorption energies and dissociation barriers of these\nmolecules on the most relevant diamond surfaces, including C(111), C(001), and\nC(110). The adsorption configurations, reaction paths, activation energies, and\ntheir influence on the structure of diamond surfaces are discussed. The results\nindicate that there is a strong correlation between adsorption energy and\nsurface energy. Moreover, we found that the dissociation processes of oxygen\nmolecules on these diamond surfaces can significantly alter the surface\nmorphology and may affect the tribological properties of diamond films. These\nfindings can help to advance the development and optimization of devices and\nantiwear coatings based on diamond."
    },
    {
        "anchor": "Influence of Fr\u00f6hlich polaron coupling on renormalized electron bands\n  in polar semiconductors. Results for zincblende GaN: \\ni We develop a simple method to study the zero-point and thermally\nrenormalized electron energy $\\varepsilon_{\\mathbf{k}n}(T)$ for $\\mathbf{k}n$\nthe conduction band minimum or valence maximum in polar semiconductors. We use\nthe adiabatic approximation, including an imaginary broadening parameter\n$i\\delta$ to supress noise in the density-functional integrations. Fr\\\"{o}hlich\npolaron methods provide analytic expressions for the contribution of the\nproblematic optical phonon mode. We use this to correct the renormalization\nobtained from the adiabatic approximation. Test calculations are done for\nzincblende GaN for an 18x18x18 integration grid. The Fr\\\"ohlich correction is\nof order -0.02 eV for the zero-point energy shift of the conduction band\nminimum, and +0.03 eV for the valence band maximum; the correction to\nrenormalization of the 3.28 eV gap is -0.05 eV, a significant fraction of the\ntotal zero point renormalization of -0.15 eV.",
        "positive": "Efficient Switching and Domain Interlocking Observed in Polyaxial\n  Ferroelectrics: We present in-situ transmission electron microscopy observations of domain\nwall motion in thin freestanding potassium niobate single-crystals. We observe\nthat not all domains of a given polarization orientation are equally switchable\nin applied electric fields. Tilted and curved 90 degree domain walls are common\nand display field-induced mobility, whereas untilted domain boundaries resist\nsuch motion. The sensitivity of the domain wall response to field direction\nsuggests that electrostatic energy contributions play a crucial role in the\nobserved switching properties. We can explain our results in terms of the\npolarization charges and the resulting depolarization fields associated with\nangled domain walls. A phenomenological Landau-Ginzburg analysis of a tilted\ndomain boundary indicates that such electrostatic effects reduce its local\nswitching barrier, thereby enhancing its field-induced mobility compared to\nthat of its untilted counterpart. Consequently not all domain walls are equally\nmobile. Furthermore the switching efficiency of a particular domain is\ndetermined by its allowed final states, as defined by its neighbors. Switching\nwill be inhibited if the relative energetics are unfavorable, and we call this\nphenomenon domain interlocking. Any increase in density of such field-resistant\nwall configurations with cycle time represents an inherent contribution to\nferroelectric fatigue. Uniaxial ferroelectrics, with polarizations parallel to\nthe field, should not support such interlocked domains."
    },
    {
        "anchor": "A Fibrous Solid Electrolyte for Lithium-ion Batteries: The new methodology proposed in this work uses oxide filaments/fibers instead\nof a dense thin film electrolyte, allowing: (i) straightforward fabrication\nwithout the use of costly thin film production techniques, (ii) minor changes\nin the existing Li- ion battery production lines, and (iii) better mechanical\nstability and electrochemical performance. Li7La3Zr2O12 (LLZO) fibers as an\nelectrolyte were prepared using the electrospinning technique. The\ncrystallographic phase and morphology of the products was studied X-ray\ndiffraction (XRD) patterns and scanning electron microscopy (SEM),\nrespectively. The results indicated that the produced electrolyte would be a\ngood alternative of all-solid-state batteries for electric vehicles in terms of\nbattery safety and performance.",
        "positive": "Hybrid deterministic and stochastic approach for efficient atomistic\n  simulations at long time scales: We propose a hybrid deterministic and stochastic approach to achieve extended\ntime scales in atomistic simulations that combines the strengths of molecular\ndynamics (MD) and Monte Carlo (MC) simulations in an easy-to-implement way. The\nmethod exploits the rare event nature of the dynamics similar to most current\naccelerated MD approaches but goes beyond them by providing, without any\nfurther computational overhead, (a) rapid thermalization between infrequent\nevents, thereby minimizing spurious correlations, and (b) control over accuracy\nof time-scale correction, while still providing similar or higher boosts in\ncomputational efficiency. We present two applications of the method: (a)\nVacancy-mediated diffusion in Fe yields correct diffusivities over a wide range\nof temperatures and (b) source-controlled plasticity and deformation behavior\nin Au nanopillars at realistic strain rates (10^4/s and lower), with excellent\nagreement with previous theoretical predictions and in situ high-resolution\ntransmission electron microscopy observations. The method gives several\norders-of-magnitude improvements in computational efficiency relative to\nstandard MD and good scalability with the size of the system."
    },
    {
        "anchor": "The vacancy - edge dislocation interaction in fcc metals: a comparison\n  between atomic simulations and elasticity theory: The interaction between vacancies and edge dislocations in face centered\ncubic metals (Al, Au, Cu, Ni) is studied at different length scales. Using\nempirical potentials and static relaxation, atomic simulations give us a\nprecise description of this interaction, mostly in the case when the separation\ndistance between both defects is small. At larger distances, elasticity theory\ncan be used to predict this interaction. From the comparison between both\napproaches we obtain the minimal separation distance where elasticity applies\nand we estimate the degree of refinement required in the calculation. In this\npurpose, isotropic and anisotropic elasticity is used assuming a perfect or a\ndissociated edge dislocation and considering the size effect as well as the\ninhomogeneity interaction.",
        "positive": "Quantum Dot Self-assembly in Growth of Strained-Layer Thin Films: a\n  Kinet ic Monte-Carlo Study: We use Monte-Carlo simulations to study island formation in the growth of\nthin semiconducting films deposited on lattice-mismatched substrates. It is\nknown that islands nucleate with critical nuclei of about one atom and grow two\ndimensionally until they reach a critical size s$_c$, when it is favorable for\nthe islands to become three dimensional.\n  We investigate the mechanism for this transition from two-dimensional(2D) to\nthree-dimensional(3D) growth. Atoms at the edge of 2D islands with the critical\nsize s$_{c}$ become mobile as a result of strain and are promoted to the next\nlevel. Edge atoms of the resulting island remain highly strained and are\npromoted to the higher layers in quick succession. This process of depletion is\nrapid and occurs at a sharply defined island size. We discuss why this leads to\nthe uniformity seen in self-assembled quantum dots in highly mismatched\nheteroepitaxy"
    },
    {
        "anchor": "Exploration of the two-dimensional Ising magnetic materials in the\n  triangular prismatic crystal field: Magnetic anisotropy is essential for stabilizing two-dimensional (2D)\nmagnetism, which has significant applications in spintronics and the\nadvancement of fundamental physics. In this work, we examine the electronic\nstructure and magnetic properties of triangular prismatic MSi$_2$N$_4$ (M = V,\nCr) monolayers, using crystal field theory, spin-orbital state analyses, and\ndensity functional calculations. Our results reveal that the pristine\nVSi$_2$N$_4$ monolayer exhibits magnetism with a V$^{4+}$ 3$d^1$ $S$ = 1/2\ncharge-spin state within the triangular prismatic crystal field. However, the\nstrong $d$ orbital hybridization between adjacent V$^{4+}$ ions disrupts the\n$d$ orbital splitting in this crystal field, resulting in a relatively small\nin-plane magnetic anisotropy of approximately 2 $\\mu$eV per V atom.In contrast,\nthe pristine CrSi$_2$N$_4$ monolayer is nonmagnetic, characterized by the\nCr$^{4+}$ 3$d^2$ $S$ = 0 state. Upon substituting nonmagnetic Cr$^{4+}$ with\nSi$^{4+}$, Cr$_\\frac{1}{3}$Si$_\\frac{8}{3}$N$_4$ transforms into an\nantiferromagnetic insulator with Cr$^{4+}$ 3$d^2$ $S$ = 1 state, featuring a\nlarge orbital moment of -1.06 $\\mu_{\\rm B}$ oriented along the $z$-axis and\nhuge perpendicular magnetic anisotropy of 18.63 meV per Cr atom. These findings\nhighlight the potential for further exploration of 2D Ising magnetic materials\nwithin a unique triangular prismatic crystal field.",
        "positive": "Observation of Single Dirac Cone Topological Surface State in Compounds\n  TlBiTe2 and TlBiSe2 from a New Topological Insulator Family: Angle resolved photoemission spectroscopy (ARPES) studies were performed on\ntwo compounds (TlBiTe$_2$ and TlBiSe$_2$) from a recently proposed three\ndimensional topological insulator family in Thallium-based III-V-VI$_2$ ternary\nchalcogenides. For both materials, we show that the electronic band structures\nare in broad agreement with the $ab$ $initio$ calculations; by surveying over\nthe entire surface Brillouin zone (BZ), we demonstrate that there is a single\nDirac cone reside at the center of BZ, indicating its topological\nnon-triviality. For TlBiSe$_2$, the observed Dirac point resides at the top of\nthe bulk valance band, making it a large gap ($\\geq$200$meV$) topological\ninsulator; while for TlBiTe$_2$, we found there exist a negative indirect gap\nbetween the bulk conduction band at $M$ point and the bulk valance band near\n$\\Gamma$, making it a semi-metal at proper doping. Interestingly, the unique\nband structures of TlBiTe$_2$ we observed further suggest TlBiTe$_2$ may be a\ncandidate for topological superconductors."
    },
    {
        "anchor": "Facile synthesis and enhanced visible light photocatalytic activity of N\n  and Zr co-doped TiO2 nanostructures from nanotubular titanic acid precursors: Zr/N co-doped TiO2 nanostructures were successfully synthesized using\nnanotubular titanic acid (NTA) as precursors by a facile wet chemical route and\nsubsequent calcination. These Zr/N-doped TiO2 nanostructures made by NTA\nprecursors show significantly enhanced visible light absorption and much higher\nphotocatalytic performance than the Zr/N-doped P25 TiO2 nanoparticles. Impacts\nof Zr/N co-doping on the morphologies, optical properties, and photocatalytic\nactivities of the NTA precursor-based TiO2 were thoroughly investigated. The\norigin of the enhanced visible light photocatalytic activity is discussed in\ndetail.",
        "positive": "Exchange interactions and Curie temperature of Ce-substituted SmCo5: A partial substitution of Sm by Ce can have drastic effects on the magnetic\nperformance, because it will introduce strain in the structure and breaks the\nlattice symmetry in a way that enhances the contribution of the Co atoms to\nmagnetocrystalline anisotropy. However, Ce substitutions, which are benefit to\nimprove the magnetocrystalline anisotropy, are detrimental to enhance the Curie\ntemperature (TC). With the requirements of wide operating temperature range of\nmagnetic devices, it is important to quantitatively explore the relationship\nbetween the TC and ferromagnetic exchange energy. In this paper we show, based\non mean-field approximation, that Ce substitution-induced tensile strain in\nSmCo5 leads to enhanced effective ferromagnetic exchange energy and TC while Ce\natom itself reduces TC."
    },
    {
        "anchor": "Comparison of long-term natural aging to artificial aging in Duralumin: The understanding of long-term aging of aeronautical materials, in particular\naluminium alloys used in the fuselage and structure of aircraft is of extreme\nimportance for airline fleets. In this work, a plate from an old aircraft\n(Breguet) was retrieved and studied in terms of microstructure and mechanical\nproperties. A comparison was made between this naturally-aged alloy and a\nmodern alloy on which different artificial aging conditions were applied. The\nold alloy exhibits a precipitation of $\\theta$-Al2Cu at grain boundaries and of\n$\\Omega$-Al2Cu on dispersoids. This non-expected nanostructure for an alloy in\nT4 state was attributed to the heat that the plate experienced during the\naircraft cycles. However, it is shown that this aging is reversible (after a\nsolution treatment). Moreover, the very long time of outdoors exposure seems to\nhave caused intergranular corrosion causing the early failure during tensile\ntests on some of the specimens. The artificial aging (low temperature,\n100{\\textdegree}C for up to 10,000h) applied on the modern 2017A alloy did not\nallow to reproduce the nanostructure of the old plate, meaning that isothermal\nconditions for artificial aging might not be appropriate in this case.",
        "positive": "Ab initio Description of Optoelectronic Properties at Defective\n  Interfaces in Solar Cells: In order to optimize the optoelectronic properties of novel solar cell\narchitectures, such as the amorphous-crystalline interface in silicon\nheterojunction devices, we calculate and analyze the local microscopic\nstructure at this interface and in bulk a-Si:H, in particular with respect to\nthe impact of material inhomogeneities. The microscopic information is used to\nextract macroscopic material properties, and to identify localized defect\nstates, which govern the recombination properties encoded in quantities such as\ncapture cross sections used in the Shockley-Read-Hall theory. To this end,\natomic configurations for a-Si:H and a-Si:H/c-Si interfaces are generated using\nmolecular dynamics. Density functional theory calculations are then applied to\nthese configurations in order to obtain the electronic wave functions. These\nare analyzed and characterized with respect to their localization and their\ncontribution to the (local) density of states. GW calculations are performed\nfor the a-Si:H configuration in order to obtain a quasi-particle corrected\nabsorption spectrum. The results suggest that the quasi-particle corrections\ncan be approximated through a scissors shift of the Kohn-Sham energies."
    },
    {
        "anchor": "Ab initio Molecular Dynamics Simulations of the Initial Stages of\n  Solid-electrolyte Interphase Formation on Lithium Ion Battery Graphitic\n  Anodes: The decomposition of ethylene carbonate (EC) during the initial growth of\nsolid-electrolyte interphase (SEI) films at the solvent-graphitic anode\ninterface is critical to lithium ion battery operations. Ab initio molecular\ndynamics simulations of explicit liquid EC/graphite interfaces are conducted to\nstudy these electrochemical reactions. We show that carbon edge terminations\nare crucial at this stage, and that achievable experimental conditions can lead\nto surprisingly fast EC breakdown mechanisms, yielding decomposition products\nseen in experiments but not previously predicted.",
        "positive": "ab initio Study of Strain-Induced Ferroelectricity in SrTiO3: Valley lines on total-energy surfaces for the zone-center distortions of\nfree-standing and in-plane strained SrTiO3 are investigated with a newly\ndeveloped first-principles structure optimization technique [Jpn. J. Appl.\nPhys. vol.43 (2004), p.6785]. The results of numerical calculations confirmed\nthat the ferroelectricity is induced, and the Curie temperature is increased,\nby applying biaxial compressive or tensile strains. Along the distortion,\nstrong nonlinear coupling between the soft- and hard-modes is demonstrated."
    },
    {
        "anchor": "Lithium Ruthenates: Controlling Dimensionality and Topology of\n  Magnetic-Ion Arrangements: In order to control the dimensionality and the topology of the arrangement of\nmagnetic Ru ions, NaCl-type lithium ruthenates have been investigated. Three\ntypes of lithium ruthenates, Li$_{3}$RuO$_{4}$, Li$_{2}$RuO$_{3}$, and\ncubic-Li$_{x}$RuO$_{1+x}$, were synthesized using a hydrothermal method. All of\nthem have NaCl-type structure, but the arrangements of the cations, Li$^{+}$\nand Ru$^{5+}$ (or Ru$^{4+}$), differ from each other. Li$_{3}$RuO$_{4}$ with\none-dimensional zigzag chains of Ru ions undergoes an antiferromagnetic\ntransition at 66 K and exhibits an irreversibile magnetism below 32 K, where\nthe zero-field-cooled susceptibility differs from the field-cooled\nsusceptibility. Li$_{2}$RuO$_{3}$ with a two-dimensional honeycomb network of\nRu ions demonstrates a paramagnetism almost independent of temperature. A novel\nruthenate cubic-Li$_{x}$RuO$_{1+x}$, in which Ru and Li randomly occupy the\ncation sites of NaCl lattice, undergoes a spin-glass transition at 10 K.",
        "positive": "Atomic scale characterization of deformation induced interfacial mixing\n  in a Cu/V nanocomposite wire: The microstructure of a Cu/V nanocomposite wire processed by cold drawing was\ninvestigated by high resolution transmission electron microscopy and atom probe\ntomography. The experimental data clearly reveal some deformation induced\ninterfacial mixing where the vanadium filaments are nanoscaled. The mixed layer\nis a 2nm wide vanadium gradient in the fcc Cu phase. This mechanical mixing\nleads to the local fragmentation and dissolution of the filaments and to the\nformation of vanadium super saturated solid solutions in fcc Cu."
    },
    {
        "anchor": "Current-driven dynamics and inhibition of the skyrmion Hall effect of\n  ferrimagnetic skyrmions in GdFeCo films: Magnetic skyrmions are swirling magnetic textures with novel characteristics\nsuitable for future spintronic and topological applications. Recent studies\nconfirmed the room-temperature stabilization of skyrmions in ultrathin\nferromagnets. However, such ferromagnetic skyrmions show undesirable\ntopological effect, the skyrmion Hall effect, which leads to their\ncurrent-driven motion towards device edges, where skyrmions could easily be\nannihilated by topographic defects. Recent theoretical studies have predicted\nenhanced current-driven behaviour for antiferromagnetically exchange-coupled\nskyrmions. Here we present the stabilization of these skyrmions and their\ncurrent-driven dynamics in ferrimagnetic GdFeCo films. By utilizing\nelement-specific X-ray imaging, we find that the skyrmions in the Gd and FeCo\nsublayers are antiferromagnetically exchange-coupled. We further confirm that\nferrimagnetic skyrmions can move at a velocity of ~50 m s-1 with reduced\nskyrmion Hall angle, {\\theta}SkHE ~20{\\deg}. Our findings open the door to\nferrimagnetic and antiferromagnetic skyrmionics while providing key\nexperimental evidences of recent theoretical studies.",
        "positive": "Understanding the effect of porosity on the polarisation-field response\n  of ferroelectric materials: This paper combines experimental and modelling studies to provide a detailed\nexamination of the influence of porosity volume fraction and morphology on the\npolarisation-electric field response of ferroelectric materials. The broadening\nof the electric field distribution and a decrease in the electric field\nexperienced by the ferroelectric ceramic medium due to the presence of\nlow-permittivity pores is examined and its implications on the shape of the\nhysteresis loop, remnant polarisation and coercive field is discussed. The\nvariation of coercive field with porosity level is seen to be complex and is\nattributed to two competing mechanisms where at high porosity levels the\ninfluence of the broadening of the electric field distribution dominates, while\nat low porosity levels an increase in the compliance of the matrix is more\nimportant. This new approach to understanding these materials enables the\nseemingly conflicting observations in the existing literature to be clarified\nand provides an effective approach to interpret the influence of pore fraction\nand morphology on the polarisation behaviour of ferroelectrics. Such\ninformation provides new insights in the interpretation of the physical\nproperties of porous ferroelectric materials to inform future effort in the\ndesign of ferroelectric materials for piezoelectric sensor, actuator, energy\nharvesting, and transducer applications."
    },
    {
        "anchor": "Anisotropic phonon DOS: the application of Rietveld and Mossbauer\n  texture analysis in aligned powders: While synthesizing the single crystals of novel materials is not always\nfeasible, orienting the layered polycrystals becomes an attractive method in\nthe studies of angular dependencies of inelastic scattering of x-rays or\nneutrons. Putting in use the Rietveld analysis of layered structures in novel\nmanganites and cuprates we develop the studies of their anisotropic properties\nwith oriented powders instead of single crystals. Densities of phonon states\n(DOS) and atomic thermal displacememts (ATD) are anisotropic in the A-site\nordered manganites LnBaMn2Oy of both y=5 and y=6 series (Ln=Y, La, Sm, Gd). We\nestablish the angular dependence of DOS on textures of arbitrary strengths,\nlink the textures observed by x-ray and gamma-ray techniques, and solve the\nproblem of disentanglement of Goldanskii-Karyagin effect (GKE) and texture in\nMoessbauer spectra.",
        "positive": "Experimental demonstration of pitfalls and remedies for precise force\n  deconvolution in frequency-modulation atomic force microscopy: Frequency-modulation atomic force microscopy provides an outstanding\nprecision of the measurement of chemical bonding forces. However, as the\ncantilever oscillates with an amplitude A that is usually on the order of\natomic dimensions or even larger, blurring occurs. To extract a force versus\ndistance curve from an experimental frequency versus distance spectrum, a\ndeconvolution algorithm to recover the force from the experimental frequency\nshift is required. It has been recently shown that this deconvolution can be an\nill-posed inversion problem causing false force-distance curves. Whether an\ninversion problem is well- or ill-posed is determined by two factors: the shape\nof the force-distance curve and the oscillation amplitude used for the\nmeasurement. A proper choice of the oscillation amplitude as proposed by the in\nection point test of Sader et al. [Nat. Nanotechnol. 13, 1088 (2018)] should\navoid ill-posedness. Here, we experimentally validate their in ection point\ntest by means of two experimental data sets: force-distance spectra over a\nsingle carbon monoxide molecule as well as a Fe trimer on Cu(111) measured with\na set of deliberately chosen amplitudes. Furthermore, we comment on typical\npitfalls which are caused by the discrete nature of experimental data and\nprovide MATLAB code which can be used by everyone to perform this test with\ntheir own data."
    },
    {
        "anchor": "The intrinsic (trap-free) transistors based on perovskite single\n  crystals with self-passivated surfaces: Lead-halide perovskites emerged as novel semiconducting materials suitable\nfor a variety of optoelectronic applications. However, fabrication of reliable\nperovskite field-effect transistors (FETs), the devices necessary for the\nfundamental and applied research on charge transport properties of this class\nof materials, has proven challenging. Here we demonstrate high-performance\nperovskite FETs based on epitaxial, single crystalline thin films of cesium\nlead bromide (CsPbBr3). An improved vapor-phase epitaxy has allowed growing\ntruly large-area, atomically flat films of this perovskite with excellent\nstructural and surface properties. FETs based on these CsPbBr3 films exhibit\ntextbook transistor characteristics, with a very low hysteresis and high\nintrinsic charge carrier mobility. Availability of such high-performance\ndevices has allowed the study of Hall effect in perovskite FETs for the first\ntime. Our magneto-transport measurements show that the charge carrier mobility\nof CsPbBr3 FETs increases on cooling, from ~ 30 cm2V-1s-1 at room temperature,\nto ~ 250 cm2V-1s-1 at 50 K, exhibiting a band transport mostly limited by\nphonon scattering. The epitaxial growth and FET fabrication methodologies\ndescribed here can be naturally extended to other perovskites, including the\nhybrid ones, thus representing a technological leap forward, overcoming the\nperformance bottleneck in research on perovskite FETs.",
        "positive": "Novel procedure to prepare cadmium stannate films using spray pyrolysis\n  technique for solar cell applications: Thin films of cadmium stannate was prepared using low cost cadmium acetate\nand tin (II) chloride precursors by spray pyrolysis technique at three\ndifferent substrate temperatures of 400, 450 and 5000 C. A novel procedure of\nsimultaneously forming additional layer, introduced for the first time in this\nwork, on the already coated cadmium stannate film reduced the sheet resistance\nfrom 160 ohms/sq to 15 ohms/sq. Further, it is identified that the formation of\nadditional layer does not affect the structural and optical properties of the\ncadmium stannate films, but improves the electrical property; thus the\nformation of additional layer seems to be an effective alternate for annealing\nthe films at high temperature in the presence of Ar, CdS, Ar/CdS mixture,\nhydrogen or nitrogen to improve the structural, electrical and optical\nproperties of the cadmium stannate films as has been reported in the\nliterature. The maximum optical transmittance value of the prepared cadmium\nstannate film is about 99.8 % and the optical band gap energy value is about\n2.9 eV."
    },
    {
        "anchor": "Atomic scale chemical fluctuation in LaSrVMoO6: A proposed halfmetallic\n  antiferromagnet: Half metallic antiferromagnets (HMAFM) have been proposed theoretically long\nago but have not been realized experimentally yet. Recently, a double\nperovskite compound, LaSrVMoO6, has been claimed to be an almost real HMAFM\nsystem. Here, we report detailed experimental and theoretical studies on this\ncompound. Our results reveal that the compound is neither a half metal nor an\nordered antiferromagnet. Most importantly, an unusual chemical fluctuation is\nobserved locally, which finally accounts for all the electronic and magnetic\nproperties of this compound.",
        "positive": "Planar penta-transition metal phosphide and arsenide as narrow-bandgap\n  semiconductors from first principle calculations: Searching for materials with single atom-thin as well as planar structure,\nlike graphene and borophene, is one of the most attractive themes in two\ndimensional materials. Herein, using density functional theory calculations, we\nhave proposed a series of single layer planar penta-transition metal phosphide\nand arsenide, i.e. TM$\\mathrm{_2}$X$\\mathrm{_4}$ (TM= Ni, Pd and Pt; X=P, As).\nAccording to the calculated phonon dispersion relation and elastic constants,\nas well as ab initio molecular dynamics simulation results, monolayers of\nplanar penta-TM$\\mathrm{_2}$X$\\mathrm{_4}$ are dynamically, mechanically, and\nthermally stable. In addition, the band structures calculated with the screened\nHSE06 hybrid functional including spin-orbit coupling show that these\nmonolayers are direct-gap semiconductors with sizeable band gaps ranging from\n0.14 eV to 0.69 eV. Besides, the optical properties in these monolayers are\nfurther investigated, where strong in-plane optical absorption with wide\nspectral range has been revealed. Our results indicate that planar\npenta-TM$\\mathrm{_2}$X$\\mathrm{_4}$ monolayers are interesting narrow gap\nsemiconductors with excellent optical properties, and may find potential\napplications in photoelectronics."
    },
    {
        "anchor": "Electric Field Enhanced Hydrogen Storage on BN Sheet: Using density functional theory we show that an applied electric field\nsubstantially improves the hydrogen storage properties of a BN sheet by\npolarizing the hydrogen molecules as well as the substrate. The adsorption\nenergy of a single H2 molecule in the presence of an electric field of 0.05\na.u. is 0.48 eV compared to 0.07 eV in its absence. When one layer of H2\nmolecules is adsorbed, the binding energy per H2 molecule increases from 0.03\neV in the field-free case to 0.14 eV/H2 in the presence of an electric field of\n0.045 a.u. The corresponding gravimetric density of 7.5 wt % is consistent with\nthe 6 wt % system target set by DOE for 2010. Once the applied electric field\nis removed, the stored H2 molecules can be easily released, thus making the\nstorage reversible.",
        "positive": "Adhesion mechanics of graphene membranes: The interaction of graphene with neighboring materials and structures plays\nan important role in its behavior, both scientifically and technologically. The\ninteractions are complicated due to the interplay between surface forces and\npossibly nonlinear elastic behavior. Here we review recent experimental and\ntheoretical advances in the understanding of graphene adhesion. We organize our\ndiscussion into experimental and theoretical efforts directed toward: graphene\nconformation to a substrate, determination of adhesion energy, and applications\nwhere graphene adhesion plays an important role. We conclude with a brief\nprospectus outlining open issues."
    },
    {
        "anchor": "Bulk topological insulators as inborn spintronics detectors: Detection and manipulation of electrons' spins are key prerequisites for\nspin-based electronics or spintronics. This is usually achieved by contacting\nferromagnets with metals or semiconductors, in which the relaxation of spins\ndue to spin-orbit coupling limits both the efficiency and the length scale. In\ntopological insulator materials, on the contrary, the spin-orbit coupling is so\nstrong that the spin direction uniquely determines the current direction, which\nallows us to conceive a whole new scheme for spin detection and manipulation.\nNevertheless, even the most basic process, the spin injection into a\ntopological insulator from a ferromagnet, has not yet been demonstrated. Here\nwe report successful spin injection into the surface states of topological\ninsulators by using a spin pumping technique. By measuring the voltage that\nshows up across the samples as a result of spin pumping, we demonstrate that a\nspin-electricity conversion effect takes place in the surface states of\nbulk-insulating topological insulators Bi1.5Sb0.5Te1.7Se1.3 and Sn-doped\nBi2Te2Se. In this process, due to the two-dimensional nature of the surface\nstate, there is no spin current along the perpendicular direction. Hence, the\nmechanism of this phenomenon is different from the inverse spin Hall effect and\neven predicts perfect conversion between spin and electricity at room\ntemperature. The present results reveal a great advantage of topological\ninsulators as inborn spintronics devices.",
        "positive": "Optimal orientation of anisotropic solids: Results are presented for finding the optimal orientation of an anisotropic\nelastic material. The problem is formulated as minimizing the strain energy\nsubject to rotation of the material axes, under a state of uniform stress. It\nis shown that a stationary value of the strain energy requires the stress and\nstrain tensors to have a common set of principal axes. The new derivation of\nthis well known coaxiality condition uses the 6-dimensional expression of the\nrotation tensor for the elastic moduli. Using this representation it is shown\nthat the stationary condition is a minimum or a maximum if an explicit set of\nconditions is satisfied. Specific results are given for materials of cubic,\ntransversely isotropic (TI) and tetragonal symmetries. In each case the\nexistence of a minimum or maximum depends on the sign of a single elastic\nconstant. The stationary (minimum or maximum) value of energy can always be\nachieved for cubic materials. Typically, the optimal orientation of a solid\nwith cubic material symmetry is not aligned with the symmetry directions.\nExpressions are given for the optimal orientation of TI and tetragonal\nmaterials, and are in agreement with results of Rovati and Taliercio\n\\cite{Rovati03} obtained by a different procedure. A new concept is introduced,\nthe strain deviation angle, which defines the degree to which a state of stress\nor strain is not optimal. The strain deviation angle is zero for coaxial stress\nand strain. An approximate formula is given for the strain deviation angle\nwhich is valid for materials that are weakly anisotropic."
    },
    {
        "anchor": "Rapid and catalyst-free CVD growth of graphene on hBN: Recently, hexagonal boron nitride (h-BN) has been shown to act as an ideal\nsubstrate to graphene by greatly improving the material transport properties\nthanks to its atomically flat surface, low interlayer electronic coupling and\nalmost perfect reticular matching. Chemical vapour deposition (CVD) is\npresently considered the most scalable approach to grow graphene directly on\nh-BN. However, for the catalyst-free approach, poor control over the shape and\ncrystallinity of the graphene grains and low growth rates are typically\nreported. In this work we investigate the crystallinity of differently shaped\ngrains and identify a path towards a real van der Waals epitaxy of graphene on\nh-BN by adopting a catalyst-free CVD process. We demonstrate the\npolycrystalline nature of circular-shaped pads and attribute the stemming of\ndifferent oriented grains to airborne contamination of the h-BN flakes. We show\nthat single-crystal grains with six-fold symmetry can be obtained by adopting\nhigh hydrogen partial pressures during growth. Notably, growth rates as high as\n100 nm/min are obtained by optimizing growth temperature and pressure. The\npossibility of synthesizing single-crystal graphene on h-BN with appreciable\ngrowth rates by adopting a simple CVD approach is a step towards an increased\naccessibility of this promising van der Waals heterostructure.",
        "positive": "Cooperating Cracks in Two-Dimensional Crystals: The pattern development of multiple cracks in extremely anisotropic solids\nsuch as bilayer or multilayer two-dimensional (2D) crystals contains rich\nphysics, which, however, remains largely unexplored. We studied crack\ninteraction across neighboring 2D layers by transmission electron microscopy\nand molecular dynamics simulations. Parallel and anti-parallel ('En-Passant')\ncracks attract and repel each other in bilayer 2D crystals, respectively, in\nstark contrast to the behaviors of co-planar cracks. We show that the misfit\nbetween in-plane displacement fields around the crack tips results in\nnon-uniform interlayer shear, which modifies the crack driving forces by\ncreating an antisymmetric component of the stress intensity factor. The\ncross-layer interaction between cracks directly leads to material toughening,\nthe strength of which increases with the shear stiffness and decreases with the\ncrack spacings. Backed by the experimental findings and simulation results, a\ntheory that marries the theory of linear elastic fracture mechanics and the\nshear-lag model is presented, which guides the unconventional approach to\nengineer fracture patterns and enhance material resistance to cracking."
    },
    {
        "anchor": "Modeling of ultrafast X-ray induced magnetization dynamics in magnetic\n  multilayer systems: In this work, we report on modelling results obtained with our recently\ndeveloped simulation tool enabling nanoscopic description of electronic\nprocesses in X-ray irradiated ferromagnetic materials. With this tool, we have\nstudied the response of Co/Pt multilayer system irradiated by an ultrafast\nextreme ultraviolet pulse at the M-edge of Co (photon energy $\\sim$ 60 eV). It\nwas previously investigated experimentally at the FERMI free-electron-laser\nfacility, using the magnetic small-angle X-ray scattering technique. Our\nsimulations show that the magnetic scattering signal from cobalt decreases on\nfemtosecond timescales due to electronic excitation, relaxation and transport\nprocesses both in the cobalt and in the platinum layers, following the trend\nobserved in the experimental data. The confirmation of the predominant role of\nelectronic processes for X-ray induced demagnetization in the regime below the\nstructural damage threshold is a step towards quantitative control and\nmanipulation of X-ray induced magnetic processes on femtosecond timescales.",
        "positive": "Screened Strong Coupling of Excitons in Multilayer WS2 with Collective\n  Plasmonic Resonances: We demonstrate the strong coupling of direct transition excitons in tungsten\ndisulfide (WS2) with collective plasmonic resonances at room temperature. We\nuse open plasmonic cavities formed by periodic arrays of metallic\nnanoparticles. We show clear anti-crossings with monolayer, bilayer and thicker\nmultilayer WS2 on top of the nanoparticle array. The Rabi energy of such hybrid\nsystem varies from 50 to 110 meV from monolayer to sixteen layers, while it\ndoes not scale with the square root of the number of layers as expected for\ncollective strong coupling. We prove that out-of-plane coupling components can\nbe disregarded since the normal field is screened due to the high refractive\nindex contrast of the dielectric layers. Even though the in-plane dipole\nmoments of the excitons decrease beyond monolayers, the strong in-plane field\ndistributed in the flake can still enhance the coupling strength with\nmultilayers. However, the screened out-of-plane field leads to the saturation\nof the Rabi energy. The achieved coherent coupling of TMD multilayers with open\ncavities could be exploited for manipulating the dynamics and transport of\nexcitons in 2D semiconductors and developing ultrafast valley/spintronic\ndevices."
    },
    {
        "anchor": "Magnetostructure of MnAs on GaAs revisited: The ferromagnetic to nonferromagnetic (&#945;-&#946;) phase transition in\nepitaxial MnAs layers on GaAs(100) is studied by x-ray magnetic circular\ndichroism and x-ray magnetic linear dichroism photoemission electron microscopy\nin order to elucidate the nature of the controversial nonferromagnetic state of\n&#946;-MnAs. In the coexistence region of the two phases the &#946; phase shows\na clear XMLD signal characteristic of antiferromagnetism. The nature and the\npossible causes of the elusiveness of this magnetic state are discussed.",
        "positive": "Optical control of magnetization of micron-size domains in\n  antiferromagnetic NiO single crystals: We propose Raman-induced collinear difference-frequency generation (DFG) as a\nmethod to manipulate dynamical magnetization. When a fundamental beam\npropagates along a threefold rotational axis, this coherent second-order\noptical process is permitted by angular momentum conservation through the\nrotational analogue of the Umklapp process. As a demonstration, we\nexperimentally obtained polarization properties of collinear magnetic DFG along\na [111] axis of a single crystal of antiferromagnetic NiO with micro\nmultidomain structure, which excellently agreed with the theoretical\nprediction."
    },
    {
        "anchor": "Oxide spin-orbitronics: spin-charge interconversion and topological spin\n  textures: Quantum oxide materials possess a vast range of properties stemming from the\ninterplay between the lattice, charge, spin and orbital degrees of freedom, in\nwhich electron correlations often play an important role. Historically, the\nspin-orbit coupling was rarely a dominant energy scale in oxides. It however\nrecently came to the forefront, unleashing various exotic phenomena connected\nwith real and reciprocal-space topology that may be harnessed in spintronics.\nIn this article, we review the recent advances in the new field of oxide\nspin-orbitronics with a special focus on spin-charge interconversion from the\ndirect and inverse spin Hall and Edelstein effects, and on the generation and\nobservation of topological spin textures such as skyrmions. We highlight the\ncontrol of spin-orbit-driven effects by ferroelectricity and give perspectives\nfor the field.",
        "positive": "Charge Density Refinement of the Si (111) 7x7 Surface: We report an experimental refinement of the local charge density at the Si\n(111) 7x7 surface utilizing a combination of x-ray and high energy electron\ndiffraction. By perturbing about a bond-centered pseudoatom model, we find\nexperimentally that the adatoms are in an anti-bonding state with the atoms\ndirectly below. We are also able to experimentally refine a charge transfer of\n0.26(4) e- from each adatom site to the underlying layers. These results are\ncompared with a full-potential all-electron density functional DFT calculation."
    },
    {
        "anchor": "Effect of spin-conserving scattering on Gilbert damping in ferromagnetic\n  semiconductors: The Gilbert damping in ferromagnetic semiconductors is theoretically\ninvestigated based on the $s$-$d$ model. In contrast to the situation in\nmetals, all the spin-conserving scattering in ferromagnetic semiconductors\nsupplies an additional spin relaxation channel due to the momentum dependent\neffective magnetic field of the spin-orbit coupling, thereby modifies the\nGilbert damping. In the presence of a pure spin current, we predict a new\ncontribution due to the interplay of the anisotropic spin-orbit coupling and a\npure spin current.",
        "positive": "Spin galvanic effect at the conducting SrTiO3 surfaces: The (001) surface of SrTiO3 were transformed from insulating to conducting\nafter Ar+ irradiation, producing a quasi two-dimensional electron gas (2DEG).\nThis conducting surface layer can introduce Rashba spin orbital coupling due to\nthe broken inversion symmetry normal to the plane. The spin splitting of such a\nsurface has recently been demonstrated by magneto-resistance and angular\nresolved photoemission spectra measurements. Here we present experiments\nevidencing a large spin-charge conversion at the surface. We use spin pumping\nto inject a spin current from NiFe film into the surface, and measure the\nresulting charge current. The results indicate that the Rashba effect at the\nsurface can be used for efficient charge-spin conversion, and the large\nefficiency is due to the multi-d-orbitals and surface corrugation. It holds\ngreat promise in oxide spintronics."
    },
    {
        "anchor": "Flow boundary conditions from nano- to micro-scales: The development of microfluidic devices has recently revived the interest in\n\"old\" problems associated with transport at, or across, interfaces. As the\ncharacteristic sizes are decreased, the use of pressure gradients to transport\nfluids becomes problematic, and new, interface driven, methods must be\nconsidered. This has lead to new investigations of flow near interfaces, and to\nthe conception of interfaces engineered at various scales to reduce flow\nfriction. In this review, we discuss the present theoretical understanding of\nflow past solid interfaces at different length scales. We also briefly discuss\nthe corresponding phenomenon of heat transport, and the influence of surface\nslip on interface driven (e.g. electro-osmotic) flows.",
        "positive": "Enhancement of the catalytic activity upon the surface of strongly\n  disordered hollow Pt nanoparticles: a First Principles investigation: A series of First Principles calculations is undertaken to characterize and\nexplain the enhancement of the catalytic activity of oxygen on top of very\ndisordered nanomaterials of Pt. As the adsorption of OH fragment on top of the\nsurfaces is known as the limiting factor in the Oxygen Reduction Reactions\n(ORR) process in these systems, our calculations propose to determine the\ninfluence of the local geometry of the various sites on the adsorption energy\nof OH in order to discover a simple descriptor allowing to predict the\nreactivity at these surfaces as a function of their morphology and strain. For\nthis purpose, the geometry of Pt slabs with various thickness (3, 5 and 7\natomic layers) including a large number of point defects are optimized in order\nto generate a very rich catalog of inequivalent sites of reactivity on both\nsurfaces of the slabs. Given the very large distortion of the geometry of the\nsites, these latter had to be categorized into several classes for which the\nbehavior with respect to catalytic activity is determined. A new descriptor\ntaking into account the distortion of the geometry of the sites is introduced,\nallowing to recover the linear dependence of the adsorption energy of OH with\nrespect to the effective coordination number of the sites, as observed in\nhighly symmetric and planar surfaces of Pt."
    },
    {
        "anchor": "Fermi surface nesting and magnetic structure of ErGa3: A three dimensional mapping of the Fermi Surface (FS) of the rare-earth\ncompound ErGa3 was determined via measurements of the angular correlation of\nthe electron-positron annihilation radiation. The topology of the electronlike\nFS does show nesting properties which are consistent with the modulated\nantiferromagnetic structure of the system. We determine the density of states\nat the Fermi energy N(EF) and the electronic contribution to the gamma constant\nto be N(EF)=16 states/Ryd/cell and gamma=2.7 (mJ/mole K^2), respectively.\nDensities rho(k) of ErGa3 and TmGa3 in the kz=0 and kz=pi/a plane of the\nBrillouin zone reconstructed from 2D ACAR data. The arrow highlights the\nnesting feature attributed to TmGa3 and ErGa3 (left and right sides,\nrespectivelty).",
        "positive": "Graphene Domain Signature of Raman Spectra of sp2 Amorphous Carbons: The paper presents a joint consideration of Raman spectra of sp2 amorphous\ncarbons alongside with the nature and type of their amorphicity. The latter was\nattributed to the enforced fragmentation. The fragments, presented with\nsize-restricted graphene domains with heteroatom necklaces in the\ncircumference, are the basic structural units (BSUs) of the solids, determining\nthem as amorphics with molecular structure. The standard G-D-2D pattern of\nRaman spectra of polycyclic aromatic hydrocarbons, sp2 amorphous carbons,\ngraphene and/or graphite crystal is attributed to BSUs graphene domains. The\nmolecular approximation allows connecting the G-D spectra image of one-phonon\nspectra with a considerable dispersion of the C=C bond lengths within graphene\ndomains, governed by size, heteroatom necklace of BSUs as well as BSUs packing.\nThe interpretation of 2D two-phonon spectra reveals a particular role of\nelectrical anharmonicity in the spectra formation and attributes this effect to\na high degree of the electron density delocalization in graphene domains."
    },
    {
        "anchor": "Transformation thermal convection: Cloaking, concentrating, and\n  camouflage: Heat can generally transfer via thermal conduction, thermal radiation, and\nthermal convection. All the existing theories of transformation thermotics and\noptics can treat thermal conduction and thermal radiation, respectively.\nUnfortunately, thermal convection has never been touched in transformation\ntheories due to the lack of a suitable theory, thus limiting applications\nassociated with heat transfer through fluids (liquid or gas). Here, we develop,\nfor the first time, a general theory of transformation thermal convection by\nconsidering the convection-diffusion equation, the Navier-Stokes equation, and\nthe Darcy law. By introducing porous media, we get a set of coupled equations\nkeeping their forms under coordinate transformation. As model applications, the\ntheory helps to show the effects of cloaking, concentrating, and camouflage.\nOur finite element simulations confirm the theoretical findings. This work\noffers a general transformation theory for thermal convection, thus revealing\nsome novel behaviors of thermal convection; it not only provides new hints on\nhow to control heat transfer by combining thermal conduction, thermal\nradiation, and thermal convection, but also benefits the study of mass\ndiffusion and other related fields that contain a set of equations and need to\ntransform velocities at the same time.",
        "positive": "Spin glass like transition in a highly concentrated Fe-C nanoparticle\n  system: A highly concentrated (17 vol.%) Fe-C nano-particle system, with a narrow\nsize distribution $d = 5.4\\pm 0.4$ nm, has been investigated using magnetic ac\nsusceptibility measurements covering a wide range of frequencies (17 mHz - 170\nHz). A dynamic scaling analysis gives evidence for a phase transition to a low\ntemperature spin-glass-like phase. The critical exponents associated with the\ntransition are $z\\nu = 10.5 \\pm 2$ and $\\beta = 1.1 \\pm 0.2$. The reason why\nthe scaling analysis works for this sample, while it may not work for other\nsamples exhibiting collective behavior as evidenced by aging phenomena, is that\nthe single particle contribution to $\\chi''$ is vanishingly small for $T>T_g$\nand hence all slow dynamics is due to collective behavior. This criterion can\nonly be fulfilled for a highly concentrated nano-particle sample with a narrow\nsize distribution."
    },
    {
        "anchor": "Online simulation powered learning modules for materials science: Simulation tools are playing an increasingly important role in materials\nscience and engineering and beyond their well established importance in\nresearch and development, these tools have a significant pedagogical potential.\nWe describe a set of online simulation tools and learning modules designed to\nhelp students explore important concepts in materials science where hands-on\nactivities with high-fidelity simulations can provide insight not easily\nacquired otherwise. The online tools, which involve density functional theory\nand molecular dynamics simulations, have been designed with non-expert\nend-users in mind and only a few clicks are required to perform most\nsimulations, yet they are powered by research-grade codes and expert users can\naccess advanced options. All tools and modules are available for online\nsimulation in nanoHUB.org and access is open and free of charge. Importantly,\ninstructors and students do not need to download or install any software. The\nlearning modules cover a range of topics from electronic structure of crystals\nand doping, plastic deformation in metals, and physical properties of polymers.\nThese modules have been used in several core undergraduate courses at Purdue's\nSchool of Materials Engineering, they are self contained, and are easy to\nincorporate into existing classes.",
        "positive": "Evolution of the Fe-3$d$ impurity band state as the origin of high Curie\n  temperature in p-type ferromagnetic semiconductor (Ga,Fe)Sb: (Ga$_{1-x}$,Fe$_x$)Sb is one of the promising ferromagnetic semiconductors\nfor spintronic device applications because its Curie temperature ($T_{\\rm C}$)\nis above 300 K when the Fe concentration $x$ is equal to or higher than ~0.20.\nHowever, the origin of the high $T_{\\rm C}$ in (Ga,Fe)Sb remains to be\nelucidated. To address this issue, we use resonant photoemission spectroscopy\n(RPES) and first-principles calculations to investigate the $x$ dependence of\nthe Fe 3$d$ states in (Ga$_{1-x}$,Fe$_x$)Sb ($x$ = 0.05, 0.15, and 0.25) thin\nfilms. The observed Fe 2$p$-3$d$ RPES spectra reveal that the Fe-3$d$ impurity\nband (IB) crossing the Fermi level becomes broader with increasing $x$, which\nis qualitatively consistent with the picture of double-exchange interaction.\nComparison between the obtained Fe-3$d$ partial density of states and the\nfirst-principles calculations suggests that the Fe-3$d$ IB originates from the\nminority-spin ($\\downarrow$) $e$ states. The results indicate that enhancement\nof the interaction between $e_\\downarrow$ electrons with increasing $x$ is the\norigin of the high $T_{\\rm C}$ in (Ga,Fe)Sb."
    },
    {
        "anchor": "DFTTK: Density Functional Theory ToolKit for High-throughput Lattice\n  Dynamics Calculations: In this work, we present a software package in Python for high-throughput\nfirst-principles calculations of thermodynamic properties at finite\ntemperatures, which we refer to as DFTTK (Density Functional Theory Tool Kit).\nDFTTK is based on the atomate package and integrates our experiences in the\nlast decades on the development of theoretical methods and computational\nsoftware. It includes task submissions on all major operating systems and task\nexecution on high-performance computing environments. The distribution of the\nDFTTK package comes with examples of calculations of phonon density of states,\nheat capacity, entropy, enthalpy, and free energy under the quasi-harmonic\nphonon scheme for the stoichiometric phases of Al, Ni, Al3Ni, AlNi, AlNi3,\nAl3Ni4, and Al3Ni5, and the fcc solution phases treated using the special\nquasirandom structures at the compositions of Al3Ni, AlNi, and AlNi3.",
        "positive": "The role of substrate bias and nitrogen doping on the structural\n  evolution and local elastic modulus of diamond-like carbon films: Diamond-like carbon (DLC) films are synthesized on Si using plasma enhanced\nchemical vapor deposition. The role of substrate bias and nitrogen doping on\nthe structural evolution and local elastic modulus of DLC films are\nsystematically investigated. Raman spectroscopic studies reveal that the amount\nof graphitic C=C sp2 bonding increases with substrate bias and nitrogen doping.\nThe density and hydrogen concentration in the films are found to vary from 0.7\nto 2.2 g/cm3 and 16 to 38 atomic %, respectively, depending upon the substrate\nbias and nitrogen concentration in the DLC films. Atomic force acoustic\nmicroscopic (AFAM) analysis shows a direct correlation between local elastic\nmodulus and structural properties estimated by Raman spectroscopy, Rutherford\nback scattering and elastic recoil detection analysis. AFAM analysis further\nconfirms the evolution of soft second phases at high substrate biases (> -150V)\nin undoped DLC films. Further, N doping leads to formation of such soft second\nphases in DLC films even at lower substrate bias of -100 V. The AFAM studies\nprovide a direct microscopic evidence for the \"sub-implantation growth model\"\nwhich predicts the formation of graphitic second phases in DLC matrix at high\nsubstrate biases."
    },
    {
        "anchor": "Spatial characteristics of nickel-titanium shape memory alloy fabricated\n  by continuous directed energy deposition: Additive manufacturing has been adopted to process nickel-titanium shape\nmemory alloys due to its advantages of flexibility and minimal defects. The\ncurrent layer-by-layer method is accompanied by a complex temperature history,\nwhich is not beneficial to the final characteristics of shape memory alloys. In\nthis study, a continuous directed energy deposition method has been proposed to\nimprove microstructure uniformity. The spatial characterization of\nnickel-titanium shape memory alloy fabricated by continuous directed energy\ndeposition is investigated to study the temperature history, phase constituent,\nmicrostructure, and mechanical properties. The results indicate that the\nfabricated specimen has a monotonic temperature history, relatively uniform\nphase distribution and microstructure morphology, as well as high compressive\nstrength (2982 MPa~3105 MPa) and strain (37.7%~41.1%). The reported method is\nexpected to lay the foundation for spatial control during the printing of\nfunctional structures.",
        "positive": "Efficient Growth and Characterization of One Dimensional Transition\n  Metal Tellurides Inside Carbon Nanotubes: Atomically thin one dimensional (1D) van der Waals wires of transition metal\nmonochalocogenides (TMMs) have been anticipated as promising building blocks\nfor integrated nanoelectronics. While reliable production of TMM nanowires has\neluded scientists over the past few decades, we finally demonstrated a bottom\nup fabrication of MoTe nanowires inside carbon nanotubes (CNTs). Still, the\ncurrent synthesis method is based on vacuum annealing of reactive MoTe2, and\nlimits access to a variety of TMMs. Here we report an expanded framework for\nhigh yield synthesis of the 1D tellurides including WTe, an unprecedented\nfamily of TMMs. Experimental and theoretical analyses revealed that the choice\nof suitable metal oxides as a precursor provides useful yield for their\ncharacterization. These TMM nanowires exhibit a significant optical absorption\nin the visible light region. More important, electronic properties of CNTs can\nbe tuned by encapsulating different TMM nanowires."
    },
    {
        "anchor": "First-order ferromagnetic transition in single-crystalline\n  (Mn,Fe)2(P,Si): (Mn,Fe)2(P,Si) single crystals have been successfully grown by flux method.\nSingle crystal diffraction demonstrates that Mn0.83Fe1.17P0.72Si0.28\ncrystallizes in a hexagonal crystal structure (space group P-62m) at both 100\nand 280 K, in the ferromagnetic and paramagnetic states, respectively. The\nmagnetization measurements show that the crystals display a first-order\nferromagnetic phase transition at their Curie temperature (TC). The preferred\nmagnetization direction in is along the c axis. A weak magnetic anisotropy of\nK1 = 0.25x106 J/m3 and K2 = 0.19x106 J/m3 is found at 5 K. These values\nindicate a soft magnetic behaviour favourable for magnetic refrigeration. A\nseries of discontinuous magnetization jumps is observed far below TC by\nincreasing the field at a constant temperature. These magnetization jumps are\nirreversible, occur spontaneously at constant temperature and magnetic field,\nbut can be restored by cycling across the first-order phase transition.",
        "positive": "Epitaxial interfaces between crystallographically mismatched materials: We report an unexpected mechanism by which an epitaxial interface can form\nbetween materials having strongly mismatched lattice constants. A simple model\nis proposed in which one material tilts out of the interface plane to create a\ncoincidence-site lattice that balances two competing geometrical criteria---low\nresidual strain and short coincidence-lattice period. We apply this model,\nalong with complementary first-principles total-energy calculations, to the\ninterface formed by molecular-beam epitaxy of cubic Fe on hexagonal GaN and\nfind excellent agreement between theory and experiment."
    },
    {
        "anchor": "A hybrid pulsed laser deposition approach to grow thin films of\n  chalcogenides: Vapor-pressure mismatched materials such as transition metal chalcogenides\nhave emerged as electronic, photonic, and quantum materials with scientific and\ntechnological importance. However, epitaxial growth of vapor-pressure\nmismatched materials are challenging due to differences in the reactivity,\nsticking coefficient, and surface adatom mobility of the mismatched species\nconstituting the material, especially sulfur containing compounds. Here, we\nreport a novel approach to grow chalcogenides - hybrid pulsed laser deposition\n- wherein an organosulfur precursor is used as a sulfur source in conjunction\nwith pulsed laser deposition to regulate the stoichiometry of the deposited\nfilms. Epitaxial or textured thin films of sulfides with variety of structure\nand chemistry such as alkaline metal chalcogenides, main group chalcogenides,\ntransition metal chalcogenides and chalcogenide perovskites are demonstrated,\nand structural characterization reveal improvement in thin film crystallinity,\nand surface and interface roughness compared to the state-of-the-art. The\ngrowth method can be broadened to other vapor-pressure mismatched chalcogenides\nsuch as selenides and tellurides. Our work opens up opportunities for broader\nepitaxial growth of chalcogenides, especially sulfide-based thin film\ntechnological applications.",
        "positive": "Equivariant graph neural network interatomic potential for Green-Kubo\n  thermal conductivity in phase change materials: Thermal conductivity is a fundamental material property that plays an\nessential role in technology, but its accurate evaluation presents a challenge\nfor theory. In this work, we demonstrate the application of $E(3)$-equivariant\nneutral network interatomic potentials within Green-Kubo formalism to determine\nthe lattice thermal conductivity in amorphous and crystalline materials. We\napply this method to study the thermal conductivity of germanium telluride\n(GeTe) as a prototypical phase change material. A single deep learning\ninteratomic potential is able to describe the phase transitions between the\namorphous, rhombohedral and cubic phases, with critical temperatures in good\nagreement with experiments. Furthermore, this approach accurately captures the\npronounced anharmonicity that is present in GeTe, enabling precise calculations\nof the thermal conductivity. In contrast, the Boltzmann transport equation\nincluding only three-phonon processes tends to overestimate the thermal\nconductivity by approximately a factor of 2 in the crystalline phases."
    },
    {
        "anchor": "Fine Boundary--Layer structure in Linear Transport Theory: This contribution identifies and characterizes a previously unrecognized\nboundary--layer structure that occurs in the context of linear transport\ntheory, with an impact on the fields of Radiative Transfer and Neutron\nTransport. The existence of this boundary layer structure, which governs the\ninteractions between different materials, or between a material and vacuum,\nplays a critical role in a correct description of transport phenomena.\nAdditionally, the boundary--layer phenomenology explains and helps bypass\ncomputational difficulties reported in the literature over the last several\ndecades.",
        "positive": "The emergence of quantum capacitance in epitaxial graphene: We found an intrinsic redistribution of charge arises between epitaxial\ngraphene, which has intrinsically n-type doping, and an undoped substrate. In\nparticular, we studied in detail epitaxial graphene layers thermally elaborated\non C-terminated $4H$-$SiC$ ($4H$-$SiC$ ($000{\\bar{1}}$)). We have investigated\nthe charge distribution in graphene-substrate systems using Raman spectroscopy.\nThe influence of the substrate plasmons on the longitudinal optical phonons of\nthe $SiC$ substrates has been detected. The associated charge redistribution\nreveals the formation of a capacitance between the graphene and the substrate.\nThus, we give for the first time direct evidence that the excess negative\ncharge in epitaxial monolayer graphene could be self-compensated by the $SiC$\nsubstrate without initial doping. This induced a previously unseen\nredistribution of the charge-carrier density at the substrate-graphene\ninterface. There a quantum capacitor appears, without resorting to any\nintentional external doping, as is fundamentally required for epitaxial\ngraphene. Although we have determined the electric field existing inside the\ncapacitor and revealed the presence of a minigap ($\\approx 4.3meV$) for\nepitaxial graphene on $4H$-$SiC$ face terminated carbon, it remains small in\ncomparison to that obtained for graphene on face terminated $Si$. The\nfundamental electronic properties found here in graphene on $SiC$ substrates\nmay be important for developing the next generation of quantum technologies and\nelectronic/plasmonic devices."
    },
    {
        "anchor": "Dynamic recrystallization in adiabatic shear banding:\n  effective-temperature model and comparison to experiments in\n  ultrafine-grained titanium: Dynamic recrystallization (DRX) is often observed in conjunction with\nadiabatic shear banding (ASB) in polycrystalline materials. The recrystallized\nnanograins in the shear band have few dislocations compared to the material\noutside of the shear band. In this paper, we reformulate the recently-developed\nLanger-Bouchbinder-Lookman (LBL) continuum theory of polycrystalline plasticity\nand include the creation of grain boundaries. While the shear-banding\ninstability emerges because thermal heating is faster than heat dissipation,\nrecrystallization is interpreted as an entropic effect arising from the\ncompetition between dislocation creation and grain boundary formation. We show\nthat our theory closely matches recent results in sheared ultrafine-grained\ntitanium. The theory thus provides a thermodynamically consistent way to\nsystematically describe the formation of shear bands and recrystallized grains\ntherein.",
        "positive": "Long-Lived Highly Emissive MOFs as Potential Candidates for\n  Multiphotonic Applications: Long-lived emissive materials based on room temperature phosphorescence (RTP)\nand thermally activated delayed fluorescence (TADF) are considered as the\ncornerstone of the development of optical sensors, security systems and\nsolid-state lighting. Nevertheless, molecular systems with these properties are\nscarce because most of them suffer from aggregation caused quenching emission\n(ACQ). One approach to address this shortcoming is by inhibiting the molecular\nmotions/vibrations by employing a fixed matrix as afforded by a metal-organic\nframework (MOF). There, the organic chromophores are confined in a crystalline\nframework, and the structure-property relationship can be designed to get\nRTP/TADF. Inspired by this, the present work explores the relation between the\nlinker arrangement and the physicochemical properties of two isochemical MOFs\nwith different crystalline structures. The denser MOF exhibits a long-lived\ngreen RTP due to a hyperfine coupling of the linkers. On the other hand, the\nmore porous MOF presents a long-lived temperature-dependent turquoise emission,\nreflecting the influence of the TADF. Hence, this study provides a huge advance\nabout the potential of MOFs to undergo RTP and TADF emission, and at the same\ntime, demonstrates their potential applicability in a wide range of photonic\ntechnologies, including physical and chemical sensing and the first example of\na MOF-LED based on RTP-MOFs."
    },
    {
        "anchor": "Material and structural optimization of metal nanowire/AAO composites\n  for high-temperature solar thermal application: In this paper, we study the solar selective absorbing properties of metal\nnanowire array (NWA) / anodic aluminum oxide (AAO) composites at 1000 K via\nnumerical simulation. The materials and structural parameters which influence\nthe wavelength absorption between 0.28 and 10 microns are simulated and\noptimized. The results reveal that W NWA / AAO composites with nanowire length\nof 7.3 microns, fill factor of 0.03, and AAO template thickness of 0.1 microns\nexhibits the best selective absorption. This composite has 0.90 solar\nabsorptivity and 0.045 thermal emissivity in 1000 K, and shows a photothermal\nconversion efficiency of 71.5 %.",
        "positive": "Vertical Heterostructures between Transition-Metal Dichalcogenides -- A\n  Theoretical Analysis of the NbS$_2$/WSe$_2$ junction: Low-dimensional metal-semiconductor vertical heterostructures (VH) are\npromising candidates in the search of electronic devices at the extreme limits\nof miniaturization. Within this line of research, here we present a\ntheoretical/computational study of the NbS$_2$/WSe$_2$ metal-semiconductor\nvertical hetero-junction using density functional theory (DFT) and conductance\nsimulations. We first construct atomistic models of the NbS$_2$/WSe$_2$ VH\nconsidering all the five possible stacking orientations at the interface, and\nwe conduct DFT and quantum-mechanical (QM) scattering simulations to obtain\ninformation on band structure and transmission coefficients. We then carry out\nan analysis of the QM results in terms of electrostatic potential, fragment\ndecomposition, and band alignment. The behavior of transmission expected from\nthis analysis is in excellent agreement with, and thus fully rationalizes, the\nDFT results, and the peculiar double-peak profile of transmission. Finally, we\nuse maximally localized Wannier functions, projected density of states (PDOS),\nand a simple analytic formula to predict and explain quantitatively the\ndifferences in transport in the case of epitaxial misorientation. Within the\nclass of Transition-Metal Dichalcogenide systems, the NbS$_2$/WSe$_2$ vertical\nheterostructure exhibits a wide interval of finite transmission and a\ndouble-peak profile, features that could be exploited in applications."
    },
    {
        "anchor": "Quasicrystalline 30\u00b0 Twisted Bilayer Graphene as an Incommensurate\n  Superlattice with Strong Interlayer Coupling: The interlayer coupling can be used to engineer the electronic structure of\nvan der Waals heterostructures (superlattices) to obtain properties that are\nnot possible in a single material. So far research in heterostructures has been\nfocused on commensurate superlattices with a long-ranged Moir\\'e period.\nIncommensurate heterostructures with rotational symmetry but not translational\nsymmetry (in analogy to quasicrystals) are not only rare in nature, but also\nthe interlayer interaction has often been assumed to be negligible due to the\nlack of phase coherence. Here we report the successful growth of\nquasicrystalline 30{\\deg} twisted bilayer graphene (30{\\deg}-tBLG) which is\nstabilized by the Pt(111) substrate, and reveal its electronic structure. The\n30{\\deg}-tBLG is confirmed by low energy electron diffraction and the\nintervalley double-resonance Raman mode at 1383 cm$^{-1}$. Moreover, the\nemergence of mirrored Dirac cones inside the Brillouin zone of each graphene\nlayer and a gap opening at the zone boundary suggest that these two graphene\nlayers are coupled via a generalized Umklapp scattering mechanism, i.e.\nscattering of Dirac cone in one graphene layer by the reciprocal lattice vector\nof the other graphene layer. Our work highlights the important role of\ninterlayer coupling in incommensurate quasicrystalline superlattices, thereby\nextending band structure engineering to incommensurate superstructures.",
        "positive": "The broad Brillouin doublets and central peak of KTaO_3: The incipient ferroelectric KTaO3 presents low-T Brillouin spectra\nanomalies,e.g. a broad central peak (CP), and some additional Brillouin\ndoublets (BD), whose origin is interpreted in terms of phonon-density\nfluctuation processes. A parameterisation from new extensive high-resolution\nneutron-scattering measurements is used to show that hydrodynamic second sound\nfrom high damping (compared to BD frequency) TA phonons may exist in the\ncrystal. Furthermore, low damping thermal phonons may scatter light through\ntwo-phonon difference processes and appear on the Brillouin spectra either as a\nsharp or a broader BD, depending on the phonon damping and group velocity . The\ncomparison between computed anisotropies and experimental measurements favours\nthe second process."
    },
    {
        "anchor": "Understanding the onset of surface degradation in LiNiO2 cathodes: Nickel-based layered oxides offer an attractive platform for the development\nof energy-dense cobalt-free cathodes for lithium-ion batteries but suffer from\ndegradation via oxygen gas release during electrochemical cycling. While such\ndegradation has previously been characterized phenomenologically with\nexperiments, an atomic-scale understanding of the reactions that take place at\nthe cathode surface has been lacking. Here, we develop a first-principles\nmethodology for the prediction of the surface reconstructions of intercalation\nelectrode particles as a function of the temperature and state of charge. We\nreport the surface phase diagrams of the LiNiO2(001) and (104) surfaces and\nidentify surface structures that are likely visited during the first charge and\ndischarge. Our calculations indicate that both surfaces experience oxygen loss\nduring the first charge, resulting in irreversible changes to the surface\nstructures. At the end of charge, the surface Ni atoms migrate into tetrahedral\nsites, from which they further migrate into Li vacancies during discharge,\nleading to Li/Ni mixed discharged surface phases. Further, the impact of the\ntemperature and voltage range during cycling on the charge/discharge mechanism\nis discussed. The present study thus provides insight into the initial stages\nof cathode surface degradation and lies the foundation for the computational\ndesign of cathode materials that are stable against oxygen release.",
        "positive": "Characterization of ultra-low carbon steel: A preliminary approach to\n  investigate the quality and standards of locally-available steel: In the present work, experimental study has been carried out to expose the\nthermal, mechanical, and microstructural properties of low carbon steel as well\nas to inspects the influence of etchant concentration and etching time on its\nmicrostructure. Ultra-low carbon steel, in the form of a sheet, was collected\nfrom the Mughal Steel Industry, Peshawar, Pakistan. The sample was chemically\netched, using Nital as an etchant, by two different methods: first, by changing\nthe etching time while keeping the composition of etchant the same and second,\nby keeping the time constant while varying the etchant composition in a range\nof 5-14 %. The microstructure analysis revealed that ultra-fine grain can be\nobtained for the etchant composition of 8 % nitric acid in ethanol.\nAdditionally, we noticed that the best etching time, for getting a clear\nmorphology, was 90 s. The X-ray diffraction revealed mainly alpha-iron. Thermal\nanalysis showed a minor weight loss followed by weight gain of 1.31 wt %.\nContraction and expansion, observed on the TDA curve, suggested the\ntransformation of BCC to FCC structure. Our results indicated that the specimen\nis highly ductile, malleable and soft."
    },
    {
        "anchor": "Magnetic properties of double perovskite $Ln_2$CoIrO$_6$ ($Ln$ = Eu, Tb,\n  Ho): hetero-tri-spin $3d$-$5d$-$4f$ systems: The field of double perovskites is now advancing to three magnetic elements\non the A, B and B$'$ sites. A series of iridium-based double perovskite\ncompounds, $Ln_2$CoIrO$_6$ ($Ln$ = Eu, Tb, Ho) with three magnetic elements\nwere synthesized as polycrystalline samples. The compounds crystalize in\nmonoclinic structures with the space group $P2_1/n$. Magnetic properties of\nthese hetero-tri-spin $3d$-$5d$-$4f$ systems were studied by magnetic\nsusceptibility and field dependent magnetization in both DC and pulsed magnetic\nfields. All these compounds show ferrimagnetic transitions at temperatures\n$T_C$ above 100 K, which are attributable to antiferromagnetic coupling between\nCo$^{2+}$ and Ir$^{4+}$ spins. For Eu$_2$CoIrO$_6$, the magnetic properties are\nsimilar to those of La$_2$CoIrO$_6$. The Eu$^{3+}$ spins show Van Vleck\nparamagnetism that don't significantly interact with transition-metal cations.\nBy contrast, Tb$_2$CoIrO$_6$ and Ho$_2$CoIrO$_6$ reveal a second transition to\nantiferromagnetic order below a lower temperature $T_N$. The\ntemperature-induced ferrimagnetic-to-antiferromagnetic phase transition might\nbe explained by a spin-reorientation transition. Moreover, a\nmagnetic-field-induced spin-flop transition with a small hysteresis was\nobserved below $T_N$ in these two compounds. The magnetic moment of all three\ncompounds do not saturate up to 60 T at low temperatures. Moderate\nmagnetocaloric effect was also observed in all three compounds. Our results\nshould motivate further investigation of the spin configuration on single\ncrystals of these iridium-based double perovskites.",
        "positive": "Stability and electronic structure of NV centers at dislocation cores in\n  diamond: We present a density functional theory analysis of the negatively charged\nnitrogen-vacancy (NV) defect complex located at or close to the core of\n30$^\\circ$ and 90$^\\circ$ partial glide dislocations in diamond. Formation\nenergies, electronic densities of states, structural deformations, hyperfine\nstructure and zero-field splitting parameters of NV centers in such\nstructurally distorted environments are analyzed. The formation energies of the\nNV centers are up to 3 eV lower at the dislocation cores compared to the bulk\nvalues of crystalline diamond. We found that the lowest energy configuration of\nthe NV center at the core of a 30$^\\circ$ partial glide dislocation is realized\nwhen the axis of the NV center is oriented parallel to the dislocation line.\nThis special configuration has a stable triplet ground state. Its hyperfine\nconstants and zero field splitting parameters deviate by only 3% from values of\nthe bulk NV center. Hence, this is an interesting candidate for a self-assembly\nof a linear array of NV centers along the dislocation line."
    },
    {
        "anchor": "Strong nonlinear optical response and transient symmetry switching in\n  Type-II Weyl semimetal $\u03b2$-WP2: The topological Weyl semimetals with peculiar band structure exhibit novel\nnonlinear optical enhancement phenomena even for light at optical wavelengths.\nWhile many intriguing nonlinear optical effects were constantly uncovered in\ntype-I semimetals, few experimental works focused on basic nonlinear optical\nproperties in type-II Weyl semimetals. Here we perform a fundamental static and\ntime-resolved second harmonic generation (SHG) on the three dimensional Type-II\nWeyl semimetal candidate $\\beta$-WP$_2$. Although $\\beta$-WP$_2$ exhibits\nextremely high conductivity and an extraordinarily large mean free path, the\nsecond harmonic generation is unscreened by conduction electrons, we observed\nrather strong SHG response compared to non-topological polar metals and\narchetypal ferroelectric insulators. Additionally, our time-resolved SHG\nexperiment traces ultrafast symmetry switching and reveals that polar metal\n$\\beta$-WP$_2$ tends to form inversion symmetric metastable state after\nphoto-excitation. Intense femtosecond laser pulse could optically drive\nsymmetry switching and tune nonlinear optical response on ultrafast timescales\nalthough the interlayer coupling of $\\beta$-WP$_2$ is very strong. Our work is\nilluminating for the polar metal nonlinear optics and potential ultrafast\ntopological optoelectronic applications.",
        "positive": "Magnon Orbital Angular Momentum of Ferromagnetic Honeycomb and Zig-Zag\n  Lattices: By expanding the gauge $\\lambda_n(k)$ for magnon band $n$ in harmonics of\nmomentum ${\\bf k} =(k,\\phi )$, we demonstrate that the only observable\ncomponent of the magnon orbital angular momentum $O_n({\\bf k})$ is its angular\naverage over all angles $\\phi$, denoted by $F_n(k)$. For both the FM honeycomb\nand zig-zag lattices, we show that $F_n(k)$ is nonzero in the presence of a\nDzyalloshinzkii-Moriya (DM) interaction. The FM zig-zag lattice model with\nexchange interactions $0<J_1< J_2$ provides a new system where the effects of\norbital angular momentum are observable. For the zig-zag model with equal\nexchange interactions $J_{1x}$ and $J_{1y}$ along the $x$ and $y$ axis, the\nmagnon bands are degenerate along the boundaries of the Brillouin zone with\n$k_x-k_y =\\pm \\pi/a$ and the Chern numbers $C_n$ are not well defined. However,\na revised model with $J_{1y}\\ne J_{1x}$ lifts those degeneracy and produces\nwell-defined Chern numbers of $C_n=\\pm 1$ for the two magnon bands. When\n$J_{1y}=J_{1x}$, the thermal conductivity $\\kappa^{xy}(T)$ of the FM zig-zag\nlattice is largest for $J_2/J_1>6$ but is still about four times smaller than\nthat of the FM honeycomb lattice at high temperatures. Due to the removal of\nband degeneracies, $\\kappa^{xy}(T)$ is slightly enhanced when $J_{1y}\\ne\nJ_{1x}$."
    },
    {
        "anchor": "Synthetic control over polymorph formation in the d-band semiconductor\n  system FeS$_2$: Pyrite, also known as fool's gold is the thermodynamic stable polymorph of\nFeS$_2$. It is widely considered as a promising d-band semiconductor for\nvarious applications due to its intriguing physical properties. Marcasite is\nthe other naturally occurring polymorph of FeS$_2$. Measurements on natural\ncrystals have shown that it has similarly promising electronic, mechanical, and\noptical properties as pyrite. However, it has been only scarcely investigated\nso far, because the laboratory-based synthesis of phase-pure samples or\nhigh-quality marcasite single crystal has been a challenge until now. Here, we\nreport the targeted phase formation via hydrothermal synthesis of marcasite and\npyrite. The formation condition and phase purity of the FeS$_2$ polymorphs are\nsystematically studied in the form of a comprehensive synthesis map. We,\nfurthermore, report on a detailed analysis of marcasite single crystal growth\nby a space-separated hydrothermal synthesis. We observe that single phase\nproduct of marcasite forms only on the surface under the involvement of H$_2$S\nand sulphur vapor. The availability of high-quality crystals of marcasite\nallows us to measure the fundamental physical properties, including an allowed\ndirect optical bandgap of 0.76 eV, temperature independent diamagnetism, an\nelectronic transport gap of 0.11 eV, and a room-temperature carrier\nconcentration of 4.14 $\\times$ 10$^{18}$ cm$^{-3}$. X-ray absorption/emission\nspectroscopy are employed to measure the band gap of the two FeS$_2$ phases. We\nfind marcasite has a band gap of 0.73 eV, while pyrite has a band gap of 0.87\neV. Our results indicate that marcasite -- that is now synthetically available\nin a straightforward fashion -- is as equally promising as pyrite as candidate\nfor various semiconductor applications based on earth abundant elements.",
        "positive": "Elastoplastic coupling to model cold ceramic powder compaction: The simulation of industrial processes involving cold compaction of powders\nallows for the optimization of the production of both traditional and advanced\nceramics. The capabilities of a constitutive model previously proposed by the\nauthors are explored to simulate simple forming processes, both in the small\nand in the large strain formulation. The model is based on the concept of\nelastoplastic coupling providing a relation between density changes and\nvariation of elastic properties and has been tailored to describe the\ntransition between a granular ceramic powder and a dense green body. Finite\nelement simulations have been compared with experiments on an alumina\nready-to-press powder and an aluminum silicate spray-dried granulate. The\nsimulations show that it is possible to take into account friction at the die\nwall and to predict the state of residual stress, density distribution and\nelastic properties in the green body at the end of the forming process."
    },
    {
        "anchor": "Multiscale tunability of solitary wave dynamics in tensegrity\n  metamaterials: A new class of strongly nonlinear metamaterials based on tensegrity concepts\nis proposed and the solitary wave dynamics under impact loading is\ninvestigated. Such systems can be tuned into elastic hardening or elastic\nsoftening regimes by adjusting local and global prestress. In the softening\nregime these metamaterials are able to transform initially compression pulse\ninto a solitary rarefaction wave followed by oscillatory tail with\nprogressively decreasing amplitude. Interaction of a compression solitary pulse\nwith an interface between elastically hardening and softening materials having\ncorrespondingly low-high acoustic impedances demonstrates anomalous behavior: a\ntrain of reflected compression solitary waves in the low impedance material;\nand a transmitted solitary rarefaction wave with oscillatory tail in high\nimpedance material. The interaction of a rarefaction solitary wave with an\ninterface between elastically softening and elastically hardening materials\nwith high-low impedances also demonstrates anomalous behavior: a reflected\nsolitary rarefaction wave with oscillatory tail in the high impedance branch;\nand a delayed train of transmitted compression solitary pulses in the low\nimpedance branch. These anomalous impact transformation properties may allow\nfor the design of ultimate impact mitigation devices without relying on energy\ndissipation.",
        "positive": "Driven Dynamics: A Probable Photodriven Frenkel-Kontorova Model: In this study, we examine the dynamics of a one-dimensional Frenkel-Kontorova\nchain consisting of nanosize clusters (the ''particles'') and photochromic\nmolecules (the ''bonds''), and being subjected to a periodic substrate\npotential. Whether the whole chain should be running or be locked depends on\nboth the frequency and the wavelength of the light (keeping the other\nparameters fixed), as observed through numerical simulation. In the locked\nstate, the particles are bound at the bottom of the external potential and\nvibrate backwards and forwards at a constant amplitude. In the running state,\nthe initially fed energy is transformed into directed motion as a whole. It is\nof interest to note that the driving energy is introduced to the system by the\nirradiation of light, and the driven mechanism is based on the dynamical\ncompetition between the inherent lengths of the moving object (the chain) and\nthe supporting carrier (the isotropic surface). However, the most important is\nthat the light-induced conformational changes of the chromophore lead to the\ntime-and-space dependence of the rest lengths of the bonds."
    },
    {
        "anchor": "Buckling effects in AlN monolayers: Shifting and enhancing optical\n  characteristics from the UV to the near visible light range: The structural, electronic, and optical properties of flat and buckled AlN\nmonolayers are investigated using first-principles approaches. The band gap of\na flat AlN monolayer is changed from an indirect one to a direct one, when the\nplanar buckling increases, primarily due to diminishing sp$^2$ overlapping and\nbond symmetry breaking in the conversion to sp$^3$ bonds. The sp$^3$\nhybridization thus results in a stronger $\\sigma\\text{-}\\pi$ bond rather than a\n$\\sigma\\text{-}\\sigma$ covalent bond. The calculations of the phonon band\nstructure indicates that the buckled AlN monolayers are structurally and\ndynamically stable. The optical properties, such as the dielectric function,\nthe refractive index, and the optical conductivity of an AlN monolayer are\nevaluated for both flat systems and those impacted with planar buckling. The\nflat AlN monolayer has outstanding optical characteristics in the Deep-UV and\nabsorbs more effectively in the UV spectrum due to its large band gap. The\nresults reveal that optical aspects are enhanced along different directions of\nlight polarization, with a considerable shift in the optical spectrum from\nDeep-UV into the visible range. Additionally, depending on the polarization\ndirection of the incoming light, increased planar buckling enhances the optical\nconductivity in both the visible and the Deep-UV domains. The ability to modify\nthe optical and electronic properties of these essential 2D materials using\nplanar buckling technique opens up new technological possibilities,\nparticularly for optoelectronic devices.",
        "positive": "Machine-learning convex and texture-dependent macroscopic yield from\n  crystal plasticity simulations: The influence of the microstructure of a polycrystalline material on its\nmacroscopic deformation response is still one of the major problems in\nmaterials engineering. For materials characterized by elastic-plastic\ndeformation responses, predictive computational models to characterize\ncrystal-plasticity (CP) have been developed. However, due to their large demand\nof computational resources, CP simulations cannot be straightforwardly\nimplemented in hierarchical computational models such as FE$^{2}$. This\nbottleneck intensifies the need for the development of macroscopic simulation\ntools that can be directly informed by microstructural quantities. Using a 3D\nFinite-Element solver for CP, we generate a macroscopic yield function database\nbased on general loading conditions and crystallographic texture. We\nfurthermore assume an independence of the yield function to hydrostatic\npressure of the yield function. Leveraging the advancement in statistical\nmodeling we describe and apply a machine learning framework for predicting\nmacroscopic yield as a function of crystallographic texture. The convexity of\nthe data-driven yield function is guaranteed by using partially input convex\nneural networks as the predictive tool. Furthermore, in order to allow for the\npredicted yield function to be directly incorporated in time-integration\nschemes, as needed for the Finite Element method, the yield surfaces are\ninterpreted as the boundaries of signed distance function level sets."
    },
    {
        "anchor": "Separation of ultrafast spin currents and spin-flip scattering in\n  Co/Cu(001) driven by femtosecond laser excitation via the complex MOKE: Ultrafast magnetization dynamics in metallic heterostructures consists of a\ncombination of local demagnetization in the ferromagnetic constituent and\nspin-dependent transport contributions within and in between the constituents.\nSeparation of these local and non-local contributions is essential to obtain\nmicroscopic understanding and for potential applications of the underlying\nmicroscopic processes. By comparing the ultrafast changes of the polarization\nrotation and ellipticity in the magneto-optical Kerr effect (MOKE) we observe a\ntime-dependent magnetization profile M(z,t) in Co/Cu(001) films by exploiting\nthe effective depth sensitivity of the method. By analyzing the spatio-temporal\ncorrelation of these profiles we find that on time scales before hot electron\nthermalization (<100 fs) the transient magnetization of Co films is governed by\nspin-dependent transport effects, while after hot electron thermalization (>200\nfs) local spin-flip processes dominate.",
        "positive": "An Alternative Definition of the Equivalent Noise Temperature of Two\n  Terminal Networks: A hypothetical test resistor is connected in parallel to a two terminal\nnetwork. The temperature of the test resistor is tuned, until there is no net\nflow of noise energy between the network and the resistor. It is shown that\nthis temperature is independent of the value of the resistor. It is therefore\nsuggested that this temperature may serve as an alternative definition of the\nequivalent noise temperature of a two terminal network. Quite interestingly,\nthis equivalent noise temperature of an ideal pn diode equals the actual\ntemperatue of the diode. Furthermore, if this newly defined equivalent noise\ntemperature can be estimated for a given network by physical arguments, than\nthe noise of the network can be calculated provided its current voltage\ndependence is known. As an example, the suppression of shot noise due to\nrecombination in the space charge region of a pn diode is estimated using this\nprocedure."
    },
    {
        "anchor": "A completely cofacial organic semiconductor: Crystals of 1,3,5-tripyrrolebenzene (TPB) contain closely packed, perfectly\ncofacial stacks of benzene rings with large wavefunction overlap, making it an\ninteresting candidate organic semiconductor. We study TPB using a variety of\nab-initio and band-structure techniques, and find very large $\\pi$ overlap in\nthe benzene stacks, broad bands (especially for electrons), and relatively\nsmall binding energies for polarons of both signs, making TPB a promising\nquasi-one dimensional electron-transport agent. We then explore the sources of\nthe unusual packing in TPB, finding that calculations of intermolecular\ninteractions using dispersion-corrected density functional theory provide\nvaluable insights into why the crystals contain perfectly cofacial\n$\\pi$-networks.",
        "positive": "ABO3 Perovskites' Formability Prediction and Crystal Structure\n  Classification using Machine Learning: Renewable energy sources are of great interest to combat global warming, yet\npromising sources like photovoltaic (PV) cells are not efficient and cheap\nenough to act as an alternative to traditional energy sources. Perovskite has\nhigh potential as a PV material but engineering the right material for a\nspecific application is often a lengthy process. In this paper, ABO3 type\nperovskites' formability is predicted and its crystal structure is classified\nusing machine learning with high accuracy, which provides a fast screening\nprocess. Although the study was done with solar-cell application in mind, the\nprediction framework is generic enough to be used for other purposes.\nFormability of perovskite is predicted and its crystal structure is classified\nwith an accuracy of 98.57% and 90.53% respectively using Random Forest after\n5-fold cross-validation. Our machine learning model may aid in the accelerated\ndevelopment of a desired perovskite structure by providing a quick mechanism to\nget insight into the material's properties in advance."
    },
    {
        "anchor": "Observation of the Topologically Originated Edge States in large-gap\n  Quasi-One-Dimensional a-Bi$_4$Br$_4$: Two-dimensional topological insulator features time-reversal-invariant\nspin-momentum-locked one-dimensional (1D) edge states with a linear energy\ndispersion. However, experimental access to 1D edge states is still of great\nchallenge and only limited to few techniques to date. Here, by using infrared\nabsorption spectroscopy, we observed robust topologically originated edge\nstates in a-Bi4Br4 belts with definitive signature of strong infrared\nabsorption at belt sides and distinct anisotropy with respect to light\npolarizations, which is further supported by first-principles calculations. Our\nwork demonstrates for the first time that the infrared spectroscopy can offer a\npower-efficient approach in experimentally probing 1D edge states of\ntopological materials.",
        "positive": "Illuminating trap density trends in amorphous oxide semiconductors with\n  ultrabroadband photoconduction: Under varying growth and device processing conditions, ultrabroadband\nphotoconduction (UBPC) reveals strongly evolving trends in the defect density\nof states (DoS) for amorphous oxide semiconductor thin-film transistors (TFTs).\nSpanning the wide bandgap of amorphous InGaZnO$_x$ (a-IGZO), UBPC identifies\nseven oxygen-deep donor vacancy peaks that are independently confirmed by\nenergetically matching to photoluminescence emission peaks. The sub-gap DoS\nfrom 15 different types of a-IGZO TFTs all yield similar DoS, except only\nback-channel etch TFTs can have a deep acceptor peak seen at 2.2 eV below the\nconduction band mobility edge. This deep acceptor is likely a zinc vacancy,\nevidenced by trap density which becomes 5-6x larger when TFT wet-etch methods\nare employed. Certain DoS peaks are strongly enhanced for TFTs with active\nchannel processing damage caused by plasma exposure. While Ar implantation and\nHe plasma processing damage are similar, Ar plasma yields more disorder showing\na 2x larger valence-band Urbach energy and two orders of magnitude increase in\nthe deep oxygen vacancy trap density. Changing the growth conditions of a-IGZO\nalso impacts the DoS, with zinc-rich TFTs showing much poorer electrical\nperformance compared to 1:1:1 molar ratio a-IGZO TFTs owing to the former\nhaving a ~10xlarger oxygen vacancy trap density. Finally, hydrogen is found to\nbehave as a donor in amorphous indium tin gallium zinc oxide TFTs."
    },
    {
        "anchor": "Structure-dependent optical and electrical transport properties of\n  nanostructured Al-doped ZnO: The structure-property relation of nanostructured Al-doped ZnO thin films has\nbeen investigated in detail through a systematic variation of structure and\nmorphology, with particular emphasis on how they affect optical and electrical\nproperties. A variety of structures, ranging from compact polycristalline films\nto mesoporous, hierarchically organized cluster assemblies, are grown by Pulsed\nLaser Deposition at room temperature at different oxygen pressures. We\ninvestigate the dependence of functional properties on structure and morphology\nand show how the correlation between electrical and optical properties can be\nstudied to evaluate energy gap, conduction band effective mass and transport\nmechanisms. Understanding these properties opens the way for specific\napplications in photovoltaic devices, where optimized combinations of\nconductivity, transparency and light scattering are required.",
        "positive": "Temperature-dependent local structure and lattice dynamics of\n  1T-TiSe$_2$ and 1T-VSe$_2$ probed by X-ray absorption spectroscopy: The local atomic structure and lattice dynamics of two isostructural layered\ntransition metal dichalcogenides (TMDs), 1T-TiSe$_2$ and 1T-VSe$_2$, were\nstudied using temperature-dependent X-ray absorption spectroscopy at the Ti, V,\nand Se K-edges. Analysis of the extended X-ray absorption fine structure\n(EXAFS) spectra, employing reverse Monte Carlo (RMC) simulations, enabled\ntracking the temperature evolution of the local environment in the range of\n10-300 K. The atomic coordinates derived from the final atomic configurations\nwere used to calculate the partial radial distribution functions (RDFs) and the\nmean-square relative displacement (MSRD) factors for the first ten coordination\nshells around the absorbing atoms. Characteristic Einstein frequencies and\neffective force constants were determined for Ti-Se, Ti-Ti, V-Se, V-V, and\nSe-Se atom pairs from the temperature dependencies of MSRDs. The obtained\nresults reveal differences in the temperature evolution of lattice dynamics and\nthe strengths of intralayer and interlayer interactions in TiSe$_2$ and\nVSe$_2$."
    },
    {
        "anchor": "Stable propagation of an ordered array of cracks during directional\n  drying: We study the appearance and evolution of an array of parallel cracks in a\nthin slab of material that is directionally dried, and show that the cracks\npenetrate the material uniformly if the drying front is sufficiently sharp. We\nalso show that cracks have a tendency to become evenly spaced during the\npenetration. The typical distance between cracks is mainly governed by the\ntypical distance of the pattern at the surface, and it is not modified during\nthe penetration. Our results agree with recent experimental work, and can be\nextended to three dimensions to describe the properties of columnar polygonal\npatterns observed in some geological formations.",
        "positive": "Where to find lossless metals?: Hypothetical metals having optical absorption losses as low as those of the\ntransparent insulators, if found, could revolutionize optoelectronics. We\nperform the first high-throughput search for lossless metals among all known\ninorganic materials in the databases of over 100,000 entries. The 381\ncandidates are identified -- having well-isolated partially-filled bands -- and\nare analyzed by defining the figures of merit and classifying their real-space\nconductive connectivity. The existing experimental evidence of most candidates\nbeing insulating, instead of conducting, is due to the limitation of current\ndensity functional theory in predicting narrow-band metals that are unstable\nagainst magnetism, structural distortion, or electron-electron interactions. We\npropose future research directions including conductive oxides, intercalating\nlayered materials, and compressing these false-metal candidates under high\npressures into eventual lossless metals."
    },
    {
        "anchor": "Controlling the oxidation of magnetic and electrically conductive\n  solid-solution iron-rhodium nanoparticles synthesized by Laser Ablation in\n  Liquids: This study focuses on the synthesis of FeRh nanoparticles via pulsed laser\nablation in liquid and on controlling the oxidation of the synthesized\nnanoparticles. Formation of monomodal {\\gamma}-FeRh nanoparticles was confirmed\nby transmission electron microscopy (TEM) and their composition confirmed by\natom probe tomography (APT). On these particles, three major contributors to\noxidation were analysed: 1) dissolved oxygen in the organic solvents, 2) the\nbound oxygen in the solvent and 3) oxygen in the atmosphere above the solvent.\nThe decrease of oxidation for optimized ablation conditions was confirmed\nthrough energy-dispersive X-ray (EDX) and M\\\"ossbauer spectroscopy.\nFurthermore, the time dependence of oxidation was monitored for dried FeRh\nnanoparticles powders using ferromagnetic resonance spectroscopy (FMR). By\nmagnetophoretic separation, B2-FeRh nanoparticles could be extracted from the\nsolution and characteristic differences of nanostrand formation between\n{\\gamma}-FeRh and B2-FeRh nanoparticles were observed.",
        "positive": "First-principles study of the effects of gold adsorption on the Al(001)\n  surface properties: In this work, we have studied theoretically the effects of gold adsorption on\nthe Al(001) surface, using {\\it ab initio} pseudo-potential method in the\nframework of the density functional theory. Having found the hollow sites at\nthe Al(001) surface as the most preferred adsorption sites, we have\ninvestigated the effects of the Au adsorption with different coverages\n($\\Theta$=0.11, 0.25, 0.50, 0.75, 1.00 ML) on the geometry, adsorption energy,\nsurface dipole moment, and the work-function of the Al(001) surface. The\nresults show that, even though the work-function of the Al substrate increases\nwith the Au coverage, the surface dipole moment decreases with the changes in\ncoverage from $\\Theta=0.11$ ML to $\\Theta=0.25$ ML. We have explained this\nbehavior by analyzing the electronic and ionic charge distributions.\nFurthermore, by studying the diffusion of Au atoms in to the substrate, we have\nshown that at room temperature the diffusion rate of Au atoms in to the\nsubstrate is negligible but, increasing the temperature to about 200$^\\circ$ C\nthe Au atoms significantly diffuse in to the substrate, in agreement with the\nexperiment."
    },
    {
        "anchor": "Two-dimensional Weyl nodal line semimetal in high Curie temperature d0\n  ferromagnet K2N monolayer: Nodal line semimetals in two-dimensional (2-D) materials have attracted\nintense attention currently. From fundamental physics and spintronic\napplications points of view, high Curie temperature ferromagnetic (FM) ones\nwith nodal lines robust against spin-orbit coupling (SOC) are significantly in\ndesirable. Here, we propose that FM K2N monolayer is such Weyl nodal line\nsemimetal. We show that K2N monolayer is dynamically stable, and has a FM\nground magnetic state with the out-of-plane [001] magnetization. It shows two\nnodal lines in the low-energy band structures. Both nodal lines are robust\nagainst SOC, under the protection of mirror symmetry. We construct an effective\nHamiltonian, which can well characterize the nodal lines in the system.\nRemarkably, the nodal line semimetal proposed here is distinct from the\npreviously studied ones in that K2N monolayer is 2-D d0-type ferromagnet with\nthe magnetism arising from the partially filled N-p orbitals, which can bring\nspecial advantages in spintronic applications. Besides, the Curie temperature\nin K2N monolayer is estimated to be 942K, being significantly higher than\nprevious FM nodal lines materials. We also find that, specific tensile strains\ncan transform the nodal line from type-I to a type-II one, making its nodal\nline characteristics even more interesting.",
        "positive": "Frustrated magnetic interactions in a Wigner-Mott insulator: Two-dimensional semiconductor moir\\'e materials have emerged as a highly\ncontrollable platform to simulate and explore quantum condensed matter.\nCompared to real solids, electrons in semiconductor moir\\'e materials are less\nstrongly attracted to the moir\\'e lattice sites, making the nonlocal\ncontributions to the magnetic interactions as important as the Anderson\nsuper-exchange. It provides a unique platform to study the effects of competing\nmagnetic interactions. Here, we report the observation of strongly frustrated\nmagnetic interactions in a Wigner-Mott insulating state at 2/3 filling of the\nmoir\\'e lattice in angle-aligned WSe2/WS2 heterobilayers. Magneto-optical\nmeasurements show that the net exchange interaction is antiferromagnetic for\nfilling factors below 1 with a strong suppression at 2/3 filling. The\nsuppression is lifted upon screening of the long-range Coulomb interactions and\nmelting of the Wigner-Mott insulator by a nearby metallic gate. The results can\nbe qualitatively captured by a honeycomb-lattice spin model with an\nantiferromagnetic nearest-neighbor coupling and a ferromagnetic second-neighbor\ncoupling. Our study establishes semiconductor moir\\'e materials as a model\nsystem for the lattice-spin physics and frustrated magnetism."
    },
    {
        "anchor": "About the effects of rotation on the Landau levels in an elastic medium\n  with a spiral dislocation: In this Paper we analyze a model proposed recently with the purpose of\nstudying the effects of rotation on the interaction of a point charge with a\nuniform magnetic field in an elastic medium with a spiral dislocation. In\nparticular we focus on the approximation proposed by the authors that consists\nof changing the left boundary condition in order to obtain analytical results.\nWe show that this approximation leads to quantitative and qualitative errors,\nthe most relevant one being a wrong prediction of the level spacing.",
        "positive": "Crossover of conduction mechanism in Sr2IrO4 epitaxial thin films: High quality epitaxial Sr2IrO4 thin films with various thicknesses (9-300 nm)\nhave been grown on SrTiO3 (001) substrates, and their electric transport\nproperties have been investigated. All samples showed the expected insulating\nbehavior with a strong resistivity dependence on film thickness, that can be as\nlarge as three orders of magnitude at low temperature. A close examination of\nthe transport data revealed interesting crossover behaviors for the conduction\nmechanism upon variation of thickness and temperature. While Mott variable\nrange hopping (VRH) dominated the transport for films thinner than 85 nm, high\ntemperature thermal activation behavior was observed for films with large\nthickness, which was followed by a crossover from Mott to Efros-Shklovskii (ES)\nVRH in the low temperature range. This low temperature crossover from Mott to\nES VRH indicates the presence of a Coulomb gap (~3 meV). Our results\ndemonstrate the competing and tunable conduction in Sr2IrO4 thin films, which\nin turn would be helpful for understanding the insulating nature related to\nstrong spin-orbit-coupling of the 5d iridates."
    },
    {
        "anchor": "Critical shell thickness for InAs-Al$_x$In$_{1-x}$As(P) core-shell\n  nanowires: InAs nanowires with Al$_x$In$_{1-x}$P or Al$x$In$_{1-x}$As shells were grown\non GaAs substrates by the Au-assisted vapour-liquid-solid (VLS) method in a gas\nsource molecular beam epitaxy (GS-MBE) system. Core diameters and shell\nthicknesses were measured by transmission electron microscopy (TEM). These\nmeasurements were then related to selected area diffraction (SAD) patterns to\nverify either interface coherency or relaxation through misfit dislocations. A\ntheoretical strain model is presented to determine the critical shell thickness\nfor given core diameters. Zincblende stiffness parameters are transformed to\ntheir wurtzite counterparts via a well known tensor transformation. An energy\ncriterion is then given to determine the shell thickness at which coherency is\nlost and dislocations become favourable.",
        "positive": "Spin Wave Excitation in Magnetic Insulator Thin Films by Spin-Transfer\n  Torque: We describe excitation of dipole-exchange spin waves in insulating magnetic\nthin films by spin current injection at the surface of the film. An easy-axis\nmagnetic surface anisotropy can induce a non-chiral surface spin wave mode with\npenetration depth inversely proportional to the strength of the surface\nanisotropy, which strongly reduces the critical current and enhances the\nexcitation power. The importance of the interface spin wave modes on the\nexcitation spectrum is reduced by spin pumping, which depends on the quality of\nthe interface as expressed by the spin mixing conductance."
    },
    {
        "anchor": "Semiconductor to metal transition in SWNTs caused by interaction with\n  gold and platinum nanoparticles: Single-walled carbon nanotubes (SWNTs) have been coated with gold and\nplatinum nanoparticles either by microwave treatment or by the click reaction\nand the Raman spectra of these SWNT-metal nanoparticle composites have been\ninvestigated. Analysis of the G bands in the Raman spectra shows an increase in\nthe proportion of metallic SWNTs on attachment with metal nanoparticles. This\nconclusion is also supported by the changes observed in the RBM bands.\nAb-initio calculations reveal that semiconductor-metal transition occurs in\nSWNTs due to Columbic charge transfer between the metal nanoparticles and the\nsemiconducting SWNTs.",
        "positive": "Influence of Periodic Surface Nanopatterning Profiles on Series\n  Resistance in Thin-Film Crystalline Silicon Heterojunction Solar Cells: In the frame of the development of thin crystalline silicon solar cell\ntechnologies, surface nanopatterning of silicon is gaining importance. Its\nimpact on the material quality is, however, not yet fully controlled.We\ninvestigate here the influence of surface nanotexturing on the series\nresistance of a contacting scheme relevant for thin-film crystalline silicon\nheterojunction solar cells. Two dimensional periodic nanotextures are\nfabricated using a combination of nanoimprint lithography and either dry or wet\netching, while random pyramid texturing is used for benchmarking. We compare\nthese texturing techniques in terms of their effect on the series resistance of\na solar cell through a study of the sheet resistance (Rsh ) and contact\nresistance (Rc) of its front layers, i.e., a sputtered transparent conductive\noxide and evaporated metal contacts. We have found by four-point probe and the\ntransfer length methods that dry-etched nanopatterns render the highest Rsh and\nRc values. Wet-etched nanopatterns, on the other hand, have less impact on Rc\nand render Rsh similar to that obtained from the nontextured case."
    },
    {
        "anchor": "First-principles prediction of Structural Stability and Thermoelectric\n  Properties of SrGaSnH: Thermoelectric materials based on earth-abundant and non-toxic elements are\nvery useful in cost-effective and eco-friendly waste heat management systems.\nThe constituents of SrGaSnH are earth-abundant and non-toxic, thus we have\nchosen SrSnGaH to study its structural stability and thermoelectric properties\nby using DFT, DFPT, and semi-classical Boltzmann transport theory. Our elastic\nand phonons calculations show that the compound has good structural stability.\nThe electronic structure calculation discloses that it is an indirect bandgap\n(0.63 eV by mBJ+SOC) semiconductor. Light band hole effective mass leads to\nhigher electrical conductivity along x-axis than that of along z-axis. On the\nother side, the weak phonon scattering leads to high lattice thermal\nconductivity ~10.5 W m-1K-1 at 300 K. Although the power factor (PF) is very\nhigh along the x-axis (above 10 mW m-1K-2 at 300 K), such large kl dramatically\nreduces ZT. The maximum values of in-plane and cross-plane ZT are ~1 (n-type),\n0.8 (p-type) and 0.6 (n-type), (0.2 p-type) at 700 K, respectively. The present\nstudy has revealed that this compound has strong potential in eco-friendly TE\napplications.",
        "positive": "Temperature-dependent dielectric response of BaTiO3 from first\n  principles: Monte Carlo simulations with an effective Hamiltonian parametrized from first\nprinciples are performed to study the dielectric response of BaTiO3 as a\nfunction of temperature, with particular emphasis on the behavior of the\ndielectric constant near the transition from the ferroelectric tetragonal phase\nto the paraelectric cubic phase."
    },
    {
        "anchor": "Deep Learning of Accurate Force Field of Ferroelectric HfO$_2$: The discovery of ferroelectricity in HfO$_2$-based thin films opens up new\nopportunities for using this silicon-compatible ferroelectric to realize\nlow-power logic circuits and high-density non-volatile memories. The functional\nperformances of ferroelectrics are intimately related to their dynamic\nresponses to external stimuli such as electric fields at finite temperatures.\nMolecular dynamics is an ideal technique for investigating dynamical processes\non large length and time scales, though its applications to new materials is\noften hindered by the limited availability and accuracy of classical force\nfields. Here we present a deep neural network-based interatomic force field of\nHfO$_2$ learned from {\\em ab initio} data using a concurrent learning\nprocedure. The model potential is able to predict structural properties such as\nelastic constants, equation of states, phonon dispersion relationships, and\nphase transition barriers of various hafnia polymorphs with accuracy comparable\nwith density functional theory calculations. The validity of this model\npotential is further confirmed by the reproduction of experimental sequences of\ntemperature-driven ferroelectric-paraelectric phase transitions of HfO$_2$ with\nisobaric-isothermal ensemble molecular dynamics simulations. We suggest a\ngeneral approach to extend the model potential of HfO$_2$ to related material\nsystems including dopants and defects.",
        "positive": "A de Hass-van Alphen study of the Type-II Dirac semimetal candidates\n  $A$Te$_2$ ($A =$ Pt, Pd): We report on a magneto-transport and quantum oscillations study on high\nquality single crystals of the transition metal di-tellurides PtTe$_2$ and\nPdTe$_2$. The de Haas-van Alphen (dHvA) oscillations in the magnetization\nmeasurements on PtTe$_2$ reveal a complicated, anisotropic band structure\ncharacterized by low effective masses and high mobilities for the carriers.\nExtracted transport parameters for PtTe$_2$ reveal a strong anisotropy which\ncould be related to the tilted nature of Dirac cone. Using a Landau level fan\ndiagram analysis we find at least one Fermi surface orbit with a Berry phase of\n$\\pi$ consistent with Dirac electrons for both PtTe$_2$ and PdTe$_2$. The light\neffective mass and high mobility are also consistent with Dirac electrons in\nPtTe$_2$. Our results suggest that similar to PdTe$_2$, PtTe$_2$ might also be\na three dimensional Dirac semimetal."
    },
    {
        "anchor": "Emergent topological states via digital (001) oxide superlattices: Oxide heterostructures exhibit many intriguing properties. Here we provide\ndesign principles for inducing multiple topological states in (001)\n($AM$O$_3$)$_1$/($AM'$O$_3$)$_1$ oxide superlattices. Aided by first-principles\ncalculations and model analysis, we show that a (Sr$M$O3)$_1$/(Sr$M'$O$_3$)$_1$\nsuperlattice ($M$ = Nb, Ta and $M'$ = Rh, Ir) is a strong topological insulator\nwith $Z_2$ index (1;001). More remarkably, a (SrMoO3)$_1$/(SrIrO3)$_1$\nsuperlattice exhibits multiple coexisting topological insulator (TI) and\ntopological Dirac semi-metal (TDS) states. The TDS state has a pair of type-II\nDirac points near the Fermi level and symmetry-protected Dirac node lines. The\nsurface TDS Dirac cone is sandwiched by two surface TI Dirac cones in the\nenergy-momentum space. The non-trivial topological properties arise from the\nband inversion between $d$ orbitals of two dissimilar transition metal atoms\nand a particular parity property of (001) superlattice geometry. Our work\ndemonstrates how to induce nontrivial topological states in (001) perovskite\noxide heterostructures by rational design.",
        "positive": "Sub-5 nm Gate-All-Around InP Nanowire Transistors Towards\n  High-Performance Devices: Gate-all-around (GAA) nanowire (NW) field-effect transistor (FET) is a\npromising device architecture due to its superior gate controllability than\nthat of the conventional FinFET architecture. The significantly higher electron\nmobility of indium phosphide (InP) NW than silicon NW makes it particularly\nwell-suited for high-performance (HP) electronics applications. In this work,\nwe perform an ab initio quantum transport simulation to investigate the\nperformance limit of sub-5-nm gate length (Lg) GAA InP NW FETs. The GAA InP NW\nFETs with Lg of 4 nm can meet the International Technology Roadmap for\nSemiconductors (ITRS) requirements for HP devices from the perspective of\non-state current, delay time, and power dissipation. We also investigate the\nimpact of strain on 3-nm-Lg GAA InP NW FETs. The application of tensile strain\nresults in a remarkable increase of over 60% in the on-state current. These\nresults highlight the potential of GAA InP NW FETs for HP applications in the\nsub-5-nm Lg region."
    },
    {
        "anchor": "Exploring the Impact of Ions on Oxygen K-Edge X-ray Absorption\n  Spectroscopy in NaCl Solution using the GW-Bethe-Salpeter-Equation Approach: X-ray absorption spectroscopy (XAS) is a powerful experimental tool to probe\nthe local structure in materials with the core hole excitations. Here, the\noxygen K-edge XAS spectra of the NaCl solution and pure water are computed by\nusing a recently developed GW-BSE approach, based on configurations modeled by\npath-integral molecular dynamics with the deep-learning technique. The neural\nnetwork is trained on ab initio data obtained with SCAN density functional\ntheory. The observed changes in the XAS features of the NaCl solution, compared\nto those of pure water, are in good agreement between experimental and\ntheoretical results. We provided detailed explanations for these spectral\nchanges that occur when NaCl is solvated in pure water. Specifically, the\npresence of solvating ion pairs leads to localization of electron-hole\nexcitons. Our theoretical XAS results support the theory that the effects of\nthe solvating ions on the H-bond network are mainly confined within the first\nhydration shell of ions, however beyond the shell the arrangement of water\nmolecules remains to be comparable to that observed in pure water.",
        "positive": "Evaluation of the electron-TO-phonon interaction in polar crystals from\n  experimental data: The aim of this study was to determine the strengths of the coupling of\nelectrons with the polar long-wavelength transverse optical (TO) vibrations\nfrom infrared spectroscopy data. This determination is made by means of a\nsimple relationship between the electron-TO-phonon interaction constant and\nmaterial parameters, based on a parametrization of the electron-TO-phonon\ncoupling in terms of the long-range dipole-dipole interaction. The combination\nof experimental data employed here allowed us to calculate directly the\nrelevant constants for a number of representative polar insulators and to show\nthat in ferroelectrics the interband electron-TO-phonon interaction at the\nGamma point is essentially strong. In these calculations, infrared spectroscopy\nmethods proved to be an effective tool for study of the main properties of\nelectron interaction with polar long-wavelength TO phonons."
    },
    {
        "anchor": "Asymmetric driven dynamics of Dzyaloshinskii domain walls in ultrathin\n  ferromagnetic strips with perpendicular magnetic anisotropy: The dynamics of domain walls in ultrathin ferromagnetic strips with\nperpendicular magnetic anisotropy is studied from both numerical and analytical\nmicromagnetics. The influence of the interfacial Dzyaloshinskii-Moriya\ninteraction associated to a bi-layer strip arrangement has been considered,\ngiving rise to the formation of Dzyaloshinskii domain walls. Such walls possess\nunder equilibrium conditions an inner magnetization structure defined by a\ncertain orientation angle that make them to be considered as intermediate\nconfigurations between Bloch and N\\'eel walls. Two different dynamics are\nconsidered, a field-driven and a current-driven dynamics, in particular, the\none promoted by the spin torque due to the Spin-Hall effect. Results show an\ninherent asymmetry associated with the rotation of the domain wall\nmagnetization orientation before reaching the stationary regime, characterized\nby a constant terminal speed. For a certain initial DW magnetization\norientation at rest, the rotation determines whether the reorientation of the\nDW magnetization prior to reach stationary motion is smooth or abrupt. This\nasymmetry affects the DW motion that can even reverse for a short period of\ntime. Additionally, it is found that the terminal speed in the case of the\ncurrent-driven dynamics may depend on either the initial DW magnetization\norientation at rest or the sign of the longitudinally injected current.",
        "positive": "Connection between charge transfer and alloying core-level shifts based\n  on density-functional calculations: The measurement of alloying core-level binding energy (CLBE) shifts has been\nused to give a precise meaning to the fundamental concept of charge transfer.\nHere, ab-initio density-functional calculations for the intermetallic compound\nMgAu are used to investigate models which try to make a connection between the\ncore levels shifts and charge transfer. The calculated CLBE shifts agree well\nwith experiment, and permit an unambiguous separation into initial-state and\nscreening contributions. Interestingly, the screening contribution is large and\ncannot be neglected in any reasonable description. Comparison of the calculated\nresults with the predictions of simple models show that these models are not\nadequate to describe the realistic situation. On the positive side, the\naccuracy of the density-functional calculations indicates that the combination\nof experiments with such calculations is a powerful tool to investigate unknown\nsystems."
    },
    {
        "anchor": "Manipulating organic semiconductor morphology with visible light: We present a method to manipulate the final morphology of roll-to-roll\nslot-die coated poly(3-hexylthiophene) (P3HT) by optically exciting the p-type\npolymer in solution while coating. Our results provide a comprehensive picture\nof the entire knowledge chain, from demonstrating how to apply our method to a\nfundamental understanding of the changes in morphology and physical properties\ninduced by exciting P3HT while coating. By combining results from density\nfunctional theory and molecular dynamics simulations with a variety of X-ray\nexperiments, absorption spectroscopy, and THz spectroscopy, we demonstrate the\nrelationship between morphology and physical properties of the thin film.\nSpecifically, in P3HT films excited with light during deposition, we observe\nchanges in crystallinity and texture with more face-on orientation and\nincreased out-of-plane charge mobility.",
        "positive": "Quantum oscillations revealing topological band in kagome metal ScV6Sn6: Compounds with kagome lattice structure are known to exhibit Dirac cones,\nflat bands, and van Hove singularities, which host numerous versatile quantum\nphenomena. Inspired by these intriguing properties, we investigate the\ntemperature and magnetic field dependent electrical transports along with the\ntheoretical calculations of ScV6Sn6, a nonmagnetic charge density wave (CDW)\ncompound. At low temperatures, the compound exhibits Shubnikov-de Haas quantum\noscillations, which help to design the Fermi surface (FS) topology. This\nanalysis reveals the existence of several small FSs in the Brillouin zone,\ncombined with a large FS. Among them, the FS possessing Dirac band is a\nnon-trivial and generates a non-zero Berry phase. In addition, the compound\nalso shows the anomalous Hall-like behaviour up to the CDW with the CDW phase,\nScV6Sn6 presents a unique material example of the versatile HfFe6Ge6 family and\nprovides various promising opportunities to explore the series further."
    },
    {
        "anchor": "A new variational approach for the Holstein Molecular Crystal Model: A new variational technique is developed to investigate the polaronic\nfeatures of the Holstein Molecular Crystal Model. It is based on a linear\nsuperposition of Bloch states that describe large and small polaron wave\nfunctions. It is shown that this method provides a very good description of the\nregime characterized by intermediate values of the electron-phonon coupling\nconstant (the so-called intermediate polaron) for any value of the adiabatic\nparameter $\\omega_0/t$. The polaron ground state energy in one and two\ndimensions is calculated and successfully compared with the best estimates\navailable providing a clear physical interpretation of the intermediate\npolaron. The band structure, the spectral weight of the ground state and the\nlattice displacement associated to the polaron are also calculated and\ndiscussed. The new method has the advantage to require a very little\ncomputational effort.",
        "positive": "Dynamics and Structural Transformations of Carbon Onion-Like under\n  High-Velocity Impacts: Carbon nano-onions (CNO) are multi-shell fullerenes. In the present work, we\nused fully atomistic reactive (ReaxFF) molecular dynamics simulations to study\nthe dynamics and structural transformations of CNO structures under\nhigh-velocity impacts against a fixed and rigid substrate. We considered single\nand multi-shell CNO (up to six shells) and at different impact velocities (from\n2 up to 7 Km/s). Our results indicated three regimes formed after the CNO\nimpact: slightly deformed CNO (quasi-elastic collision, below 2.0 Km/s),\ncollapsed CNO (inelastic collisions, between 3.0 and 5.0 Km/s) forming a\ndiamondoid-like core, and fragmented CNO yielding linear atomic carbon chains\n(above 5.0 Km/s). We also discussed the dynamical reconfiguration of\ncarbon-carbon bonds during the collision process. The impact of CNO against the\nsubstrate yielded $sp^3$-like bond types for all the used initial velocities.\nAt intermediate velocities (between 3.0 and 5.0 Km/s), the inelastic collision\nforms diamondoid-like cores by converting a substantial quantity of $sp^2$\nbonds into $sp^3$ ones. In the high velocities regime, the total number of\n$sp^1$, $sp^2$, and $sp^3$ bonds tend to be similar."
    },
    {
        "anchor": "Local distortion of MnO$_6$ octahedron in\n  La$_{1-x}$Sr$_x$MnO$_{3+\u03b4}$ (x = 0.1 to 0.9): an EXAFS study: Room temperature Mn K-edge extended x-ray absorption fine structure (EXAFS)\nstudies were carried out on La$_{1-x}$Sr$_x$MnO$_{3+\\delta}$ (x = 0.1 to 0.9)\ncompounds. It is found from the detailed EXAFS analysis that the local\nstructure around Mn sites is different from the global structure inferred from\nx-ray diffraction, especially for x <= 0.4, indicating presence of local\ndistortions in MnO$_6$ octahedra. For the rhombohedral compounds, x = 0.1 to\n0.3 the distortion is maximum for x = 0.1 and two bond lengths are seen- short\none in basal plane and long one in apical plane. For compounds with x = 0.4 to\n0.8 two short bonds in basal plane and four long bonds- two in the basal plane\nand remaining two in the apical plane are seen. For the compounds up to x = 0.3\ncompositions long bond length decreases and short bond length increases with\nincrease in x whereas for the compounds 0.4 <= x <= 0.8 both types of bond\nlengths decrease. Such behaviour of bond lengths is an indication of the\nchanged nature of distortion from Jahn-Teller type to breathing type at x = 0.4\ncomposition.",
        "positive": "Channeling of a sub-angstrom electron beam in a crystal mapped to\n  two-dimensional molecular orbitals: The propagation of high-energy electrons in crystals is in general a\ncomplicated multiple scattering problem. However, along high-symmetry zone axes\nthe problem can be mapped to the time evolution of a two-dimensional (2D)\nmolecular system. Each projected atomic column can be approximated by the\npotential of a 2D screened hydrogenic atom. When two columns are in close\nproximity, their bound states overlap and form analogs to molecular orbitals.\nFor sub-angstrom electron beams, excitation of anti-symmetric orbitals can\nresult in the failure of the simple incoherent imaging approximation. As a\nresult, the standard resolution test and the one-to-one correspondence of\natomic positions of a crystal imaged along a zone-axis with closely spaced\nprojected columns (\"dumbbells\") can fail dramatically at finite and realistic\nsample thicknesses. This is demonstrated experimentally in high angle annular\ndark field scanning transmission electron microscope (HAADF STEM) images of\n[211]-oriented Si showing an apparent inter-column spacing of 1.28(+-.09)\nAngstroms, over 64% larger than the actual 0.78 Angstrom spacing. Furthermore,\nthe apparent spacing can be tuned with sample thickness and probe size to\nproduce a larger, smaller, or even the actual spacing under conditions when the\npeaks of two adjacent Si columns should not even have been resolved given the\nelectron probe size."
    },
    {
        "anchor": "Simulation of hydrogen diffusion and boron passivation in crystalline\n  silicon: The model of hydrogen migration and of the reactions of hydrogen atoms with\nelectrically active impurity, developed earlier, has been applied to simulate\nhydrogen diffusion and passivation process during plasma deuteration of silicon\nsubstrates doped with boron. The calculated deuterium concentration profiles\nagree well in the length of the passivated region with the experimental data\nobtained on treatment in hydrogen plasma at a temperature of 200 Celsius\ndegrees for 5, 10, and 15 minutes. On the other hand, to achieve a good fit to\nthe abruptness of the calculated profiles between the passivated and\nunpassivated regions, it is necessary to suppose that the values of the\nparameters that describe the absorption of hydrogen interstitials by\nelectrically active dopant atoms decrease with increase in the depth of the\npassivated region. For example, nonuniform spatial distributions of\nnonequilibrium point defects generated during plasma treatment can lead to a\nspatial dependence of hydrogen absorption.",
        "positive": "Binding energy of singlet excitons and charge transfer complexes in\n  MDMO-PPV:PCBM solar cells: The influence of an external electric field on the photoluminescence\nintensity of singlet excitons and charge transfer complexes is investigated for\na poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV)\ndiode and a bulk heterojunction of the PPV in combination with [6,6]-phenyl-C61\nbutyric acid methylester (PCBM), respectively. The experimental data is related\nto the dissociation probability derived from the Onsager-Braun model. In this\nway, a lower limit for the singlet exciton binding energy of MDMO-PPV is\ndetermined as (327 +- 30) meV, whereas a significantly lower value of (203 +-\n18) meV is extracted for the charge transfer complex in a MDMO-PPV:PCBM blend."
    },
    {
        "anchor": "Steady-state mode III cracks in a viscoelastic lattice model: We extend the Slepyan solution of the problem of a steady-state crack in an\ninfinite ideally brittle lattice model to include dissipation in the form of\nKelvin viscosity. As a demonstration of this technique, based on the\nWiener-Hopf method, we apply the method to mode III cracks in a square lattice.\nWe use this solution to find the critical velocity at which the steady-state\nsolution becomes inconsistent due to additional bond-breaking; this point\nsignaling the onset of complex dynamical behavior.",
        "positive": "Density Functional Theory of Material Design$:$ Fundamentals and\n  Applications$-II$: This is the second and the final part of the review on density functional\ntheory (DFT), referred to as DFT-II. In the first review, DFT-I, we have\ndiscussed wavefunction-based methods, their complexity, and the basic of\ndensity functional theory. In DFT-II, we focus on fundamentals of DFT and their\nimplications for the betterment of the theory. We start our presentation with\nthe exact DFT result followed by the concept of exchange-correlation (xc) or\nFermi-Coulomb hole and its relation with xc energy functional. We also provide\nthe exact conditions for the xc-hole, xc-energy and xc-potential along with\ntheir physical interpretation. Next, we describe the extension of DFT for\nnon-integer numbers of electrons, the piecewise linearity of total energy and\ndiscontinuity of chemical potential at integer particle numbers, and derivative\ndiscontinuity of the xc potential, which has consequences on fundamental gap of\nsolids. After that, we present how one obtain more accurate xc energy\nfunctionals by going beyond LDA. We discuss the gradient expansion\napproximation (GEA), generalized gradient approximation (GGA), and hybrid\nfunctional approaches to designing better xc energy functionals that give\naccurate total energies but fail to predict properties like the ionization\npotential and the band gap. Thus, we describe different methods of modeling\nthese potentials and the results of their application for the calculation of\nthe band gaps of different solids to highlight accuracy of different xc\npotential. Finally, we conclude with a glimpse on orbital-free density\nfunctional theory and the machine learning approach ."
    },
    {
        "anchor": "Ground State Phase Diagrams and Magnetic Properties of the Double\n  Perovskite Pb2FeReO6: The Half-Metallic Ferromagnetic behavior of some double perovskites attracts\nmuch interest. In this work, we studied the magnetic behavior of the double\nperovskite Pb2FeReO6. The magnetic atoms are Fe and Re and have the spins S=5/2\nand {\\sigma}=1, respectively. In a first step, we provide a theoretical study\nof the ground state phase diagrams .In fact, we present and discuss the stable\nconfigurations from the all 6x3=18 possible configurations. Secondly, the\nmagnetic properties of this compound when varying different physical parameters\nis carried out. Besides, we used Monte Carlo simulations (MCS), under the\nMetropolis algorithm to provide the magnetic behavior of the studied system as\na function of the temperature, the crystal field, the exchange coupling\ninteractions and the external magnetic field. In addition, we studied and\ndiscussed the critical temperature of the double perovskite Pb2FeReO6. To\ncomplete our study, we presented and analyzed the hysteresis loops for specific\nvalues of physical parameters.",
        "positive": "Size and Defect related Broadening of Photoluminescence Spectra in\n  ZnO:Si Nanocomposite Films: Nanocomposite films of Zinc Oxide and Silicon were grown by thermal\nevaporation technique using varying ratios of ZnO:Si in the starting material.\nAnalysis reveal the role of ZnO and amorphous silicon interface in contributing\nto relatively less common blue photoluminescence emissions (at $\\sim$ 400 and\n470nm). These blue peaks are observed along with the emissions resulting from\nband edge transition (370nm) and those related to defects (522nm) of ZnO.\nCareful analysis shows that along with the grain size of ZnO, a suitable\ncompositional ratio (of ZnO to silicon) is critical for the coexistence of all\nthe four peaks. Proper selection of conditions can give comparable\nphotoluminescence peak intensities leading to broad-band emission."
    },
    {
        "anchor": "Prediction of mechanical properties of non-equiatomic high-entropy alloy\n  by atomistic simulation and machine learning: High-entropy alloys (HEAs) with multiple constituent elements have been\nextensively studied in the past 20 years due to their promising engineering\napplication. Previous experimental and computational studies of HEAs focused\nmainly on equiatomic or near equiatomic HEAs. However, there is probably far\nmore treasure in those non-equiatomic HEAs with carefully designed composition.\nIn this study, molecular dynamics (MD) simulation combined with machine\nlearning (ML) methods were used to predict the mechanical properties of\nnon-equiatomic CuFeNiCrCo HEAs. A database was established based on a tensile\ntest of 900 HEA single-crystal samples by MD simulation. We investigated and\ncompared eight ML models for the learning tasks, ranging from shallow models to\ndeep models. It was found that the kernel-based extreme learning machine (KELM)\nmodel outperformed others for the prediction of yield stress and Young's\nmodulus. The accuracy of the KELM model was further verified by the large-sized\npolycrystal HEA samples.",
        "positive": "Temperature dependent phonon renormalization in metallic nanotubes: We measure the temperature dependence of the Raman spectra of metallic and\nsemiconducting nanotubes. We show that the different trend in metallic tubes is\ndue to phonon re-normalization induced by the variation in electronic\ntemperature, which is modeled including non-adiabatic contributions to account\nfor the dynamic, time dependent nature"
    },
    {
        "anchor": "Mixed excitonic nature in water-oxidized BiVO$_4$ surfaces with defects: BiVO$_4$ is a promising photocatalyst for efficient water oxidation, with\nsurface reactivity determined by the structure of active catalytic sites.\nSurface oxidation in the presence of oxygen vacancies induces electron\nlocalization, suggesting an atomistic route to improve the charge transfer\nefficiency within the catalytic cycle. In this work, we study the effect of\noxygen vacancies on the electronic and optical properties at BiVO$_4$ surfaces\nupon water oxidation. We use density functional theory and many-body\nperturbation theory to explore the change in the electronic and quasiparticle\nenergy levels and to evaluate the electron-hole coupling as a function of the\nunderlying structure. We show that while the presence of defects alters the\natomic structure and largely modifies the wavefunction nature, leading to\ndefect-localized states at the quasipatricle gap region, the optical\nexcitations remain largely unchanged due to substantial hybridization of defect\nand non-defect electron-hole transitions. Our findings suggest that\ndefect-induced surface oxidation supports improved electron transport, both\nthrough bound and tunable electronic states and via a mixed nature of the\noptical transitions, expected to reduce electron-hole defect trapping.",
        "positive": "IR-stimulated visible fluorescence in pink and brown diamond: Irradiation of natural pink and brown diamond by middle-ultraviolet light\n(photon energy > 4.1 eV) is seen to induce anomalous fluorescence phenomena at\nN3 defect centres (structure N3-V). When diamonds primed in this fashion are\nsubsequently exposed to infrared light (even with a delay of many hours), a\ntransient burst of blue N3 fluorescence is observed. The dependence of this\nIR-triggered fluorescence on pump wavelength and intensity suggest that this\nfluorescence phenomena is intrinsically related to pink diamond photochromism.\nAn energy transfer process between N3 defects and other defect species can\naccount for both the UV-induced fluorescence intensity changes, and the\napparent optical upconversion of IR light. From this standpoint, we consider\nthe implications of this N3 fluorescence behaviour for the current\nunderstanding of pink diamond photochromism kinetics."
    },
    {
        "anchor": "Optical properties and Mechanical properties of C, Si, Ge and 3C-SiC\n  Materials Calculated from First Principles Theory: First-principles calculations based on Density functional theory (DFT) and\nHeyd, Scuseria and Ernzerhof (HSE) adopt PBE approximation-a new version of the\ngeneralized gradient approximation (GGA). It has studied lattice parameter,\nelectronic structure, optical properties and mechanical properties of\nmaterials, including diamond-C and zinc-blende structure of Si, Ge, 3C-SiC. The\nresult of HSE calculation is obviously superior to DFT calculation and accord\nwell with the existing experimental values. It indicates that they are indirect\nbandgap materials from the figure of band structure and density of states. The\nbandgap which it calculated using HSE accords well with the existing\nexperimental values except Ge. In the calculation of optical property, it shows\nthat they correspond with the existing experimental values from the imaginary\npart of analytical dielectric function to the refractive index and adsorption\ncoefficient. It demonstrates that they exists the corresponding relationship\namong the peak of the imaginary part of analytical dielectric function, the\nrefractive index and adsorption coefficient. The optical property has a direct\nrelationship with the distribution of crystal bandgap and electronic state\ndensity. From the results of mechanical properties it can know that they are\nbrittle materials. Though the hardness and stiffness of 3C-SiC is lower than\ndiamond, it is superior to the materials of Si, Ge as excellent semiconductor\nmaterials. In addition, the mechanical anisotropy of four materials is\ninconspicuous; the anisotropy of Diamond-C is very inconspicuous from\nanisotropic properties of Young modulus.",
        "positive": "Crystallographic image processing for scanning probe microscopy: Scanning probe microscopy (SPM) images of regularly arranged spatially\nperiodic objects can be processed crystallographically. The resulting\ninformation may be used to remove from the SPM image distortions that are due\nto a less than perfect imaging process. The combined effects of these\ndistortions result in a point spread function that gives a quantitative measure\nof the performance of the microscope for a certain set of experimental\nconditions. On the basis of highly symmetric calibration samples, the point\nspread function of the microscope may be extracted and utilized for the\ncorrection of SPM images of unknowns that were recorded under essentially the\nsame experimental conditions. We concentrate in this paper on more theoretical\naspects of our method. A blunt scanning tunneling microscopy (STM) tip that\nconsists of multiple mini-tips with electron orbital dimensions may be\nsymmetrized on the basis of prior knowledge on the plane symmetry of a\ntwo-dimensional periodic array. This is illustrated with the crystallographic\nprocessing of a STM image of a regular array of fluorinated cobalt\nphthalocyanine molecules on graphite and backed up conceptually by simple\nsimulations."
    },
    {
        "anchor": "Thermomechanical properties of amorphous metallic tungsten-oxygen and\n  tungsten-oxide coatings: In this work, we investigate the correlation between morphology, composition,\nand the mechanical properties of metallic amorphous tungsten-oxygen and\namorphous tungsten-oxide films deposited by Pulsed Laser Deposition. This\ncorrelation is investigated by the combined use of Brillouin Spectroscopy and\nthe substrate curvature method. The stiffness of the films is strongly affected\nby both the oxygen content and the mass density. The elastic moduli show a\ndecreasing trend as the mass density decreases and the oxygen-tungsten ratio\nincreases. A plateaux region is detected in correspondence of the transition\nbetween metallic and oxide films. The compressive residual stresses, moderate\nstiffness and high local ductility that characterize compact amorphous\ntungsten-oxide films make them promising for applications involving thermal or\nmechanical loads. The coefficient of thermal expansion is quite high (i.e. 8.9\n$\\cdot$ 10$^{-6}$ K$^{-1}$), being strictly correlated to the amorphous\nstructure and stoichiometry of the films. Under thermal treatments they show a\nquite low relaxation temperature (i.e. 450 K). They crystallize into the\n$\\gamma$ monoclinic phase of WO$_3$ starting from 670 K, inducing an increase\nby about 70\\% of material stiffness.",
        "positive": "Intrinsic long range antiferromagnetic coupling in dilutely V doped\n  CuInTe$_2$: Despite the various magnetic orders mediated by superexchange mechanism, the\nexistence of a long range antiferromagnetic (AFM) coupling is unknown. Based on\nDFT calculations, we discovered an intrinsic long range AFM coupling in V doped\nCuInTe$_2$. The AFM coupling is mainly due to the $p-d$ coupling and electron\nredistribution along the interacting chains. The relatively small energy\ndifference between $p$ and $d$ orbitals and the small energy difference between\nd orbitals of the dopants and that of stepping stone sites can enhance the\nstability of this AFM configuration. A multi-bands Hubbard model was proposed\nto provide fundamental understanding to the long range AFM coupling in\nchalcopyrite diluted magnetic semiconductors(DMS)."
    },
    {
        "anchor": "Atomistically enabled nonsingular anisotropic elastic representation of\n  near-core dislocation stress fields in $\u03b1$-iron: The stress fields of dislocations predicted by classical elasticity are known\nto be unrealistically large approaching the dislocation core, due to the\nsingular nature of the theory. While in many cases this is remedied with the\napproximation of an effective core radius, inside which ad hoc regularizations\nare implemented, such approximations lead to a compromise in the accuracy of\nthe calculations. In this work, an anisotropic non-singular elastic\nrepresentation of dislocation fields is developed to accurately represent the\nnear-core stresses of dislocations in $\\alpha$-iron. The regularized stress\nfield is enabled through the use of a non-singular Green's tensor function of\nHelmholtz-type gradient anisotropic elasticity, which requires only a single\ncharacteristic length parameter in addition to the material's elastic\nconstants. Using a novel magnetic bond-order potential to model atomic\ninteractions in iron, molecular statics calculations are performed, and an\noptimization procedure is developed to extract the required length parameter.\nResults show the method can accurately replicate the magnitude and decay of the\nnear-core dislocation stresses even for atoms belonging to the core itself.\nComparisons with the singular isotropic and anisotropic theories show the\nnon-singular anisotropic theory leads to a substantially more accurate\nrepresentation of the stresses of both screw and edge dislocations near the\ncore, in some cases showing improvements in accuracy of up to an order of\nmagnitude. The spatial extent of the region in which the singular and\nnon-singular stress differ substantially is also discussed. The general\nprocedure we describe may in principle be applied to accurately model the\nnear-core dislocation stresses of any arbitrarily shaped dislocation in\nanisotropic cubic media.",
        "positive": "Transition-metal dichalcogenide heterostructure solar cells: A numerical\n  study: We evaluate the tunneling short-circuit current density $J_{TU}$ in a\n$p$-$i$-$n$ solar cell in which the transition metal dichalcogenide\nheterostructure (MoS$_2$/WS$_2$ superlattice) is embedded in the intrinsic $i$\nregion. The effects of varying well and barrier widths, Fermi energy levels and\nnumber of quantum wells in the $i$ region on $J_{TU}$ are examined. A similar\nanalysis is performed for the thermionic current $J_{TH}$ that arises due to\nthe escape and recapture of charge carriers between adjacent potential wells in\nthe $i$-region. The interplay between $J_{TU}$ and $J_{TH}$ in the temperature\nrange (300 K - 330 K) is examined. The thermionic current is seen to exceed the\ntunneling current considerably at temperatures beyond 310 K, a desirable\nattribute in heterostructure solar cells. This work demonstrates the\nversatility of monolayer transition metal dichalcogenides when utilized as\nfabrication materials for van der Waals heterostructure solar cells."
    },
    {
        "anchor": "Precipitation during high temperature aging of Al-Cu alloys: a\n  multiscale analysis based on first principles calculations: Precipitation during high temperature aging of Al-Cu alloys is analyzed by\nmeans of the integration of classical nucleation theory and phase-field\nsimulations into a multiscale modelling approach based on well-established\nthermodynamics principles. In particular, thermal stability of ${\\theta}''$,\n${\\theta}'$ and ${\\theta}$ precipitates was assessed from first principles\ncalculations of the Helmholtz free energy while homogeneous and heterogeneous\nnucleation of ${\\theta}''$ and ${\\theta}'$ was analysed using classical\nnucleation theory. Precipitate growth was finally computed by means of\nmesoscopic phase-field model. The model parameters that determine\nquantitatively the driving forces for each transformation were obtained by\nmeans of first principles calculations and computational thermodynamics. The\npredictions of the models were in good agreement with experimental results and\nprovided a comprehensive understanding of the precipitation pathway in Al-Cu\nalloys. It is envisaged that the strategy presented in this investigation can\nbe used in the future to design optimum microstructures based on the\ninformation of the different energy contributions obtained from first\nprinciples calculations.",
        "positive": "Submolecular resolution by variation of IETS amplitude and its relation\n  to AFM/STM signal: Here we show scanning tunnelling microscopy (STM), non-contact atomic force\nmicroscopy (AFM) and inelastic electron tunnelling spectroscopy (IETS)\nmeasurements on organic molecule with a CO- terminated tip at 5K. The\nhigh-resolution contrast observed simultaneously in all channels unam-\nbiguously demonstrates the common imaging mechanism in STM/AFM/IETS, related to\nthe lateral bending of the CO-functionalized tip. The IETS spectroscopy reveals\nthat the submolecular con- trast at 5K consists of both renormalization of\nvibrational frequency and variation of the amplitude of IETS signal. This\nfinding is also corroborated by first principles simulations. We extend accord-\ningly the probe-particle AFM/STM/IETS model to include these two main\ningredients necessary to reproduce the high-resolution IETS contrast. We also\nemploy the first principles simulations to get more insight into different\nresponse of frustrated translation and rotational modes of CO-tip during\nimaging."
    },
    {
        "anchor": "Characterization of ZnO:Si Nanocomposite Films Grown by Thermal\n  Evaporation: Nanocomposite thin films of Zinc Oxide and Silicon were grown by\nco-evaporating powdered ZnO and Si. This resulted in nanocrystallites of ZnO\nbeing embedded in Silicon. The mismatch in crystal structures of constituent\nmaterials result in the ZnO nanocrystals to exist in a state of stress. This\nalong with oxygen vacancies in the samples result in good Photoluminescence\nemission at 520nm. Also, Silicon background gave a photoluminescence emission\nat 620nm. The structure was found quite stable over time since the homgenously\ndispersed ZnO nanocrystals do not agglomerate. The nanocomposites promises to\nbe a useful candidate for future optoelectronic devices.",
        "positive": "Ultrafast Thermal Modification of Strong Coupling in an Organic\n  Microcavity: There is growing interest in using strongly coupled organic microcavities to\ntune molecular dynamics, including the electronic and vibrational properties of\nmolecules. However, very little attention has been paid to the utility of\ncavity polaritons as sensors for out-of-equilibrium phenomena, including\nthermal excitations. Here, we demonstrate that non-resonant infrared excitation\nof an organic microcavity system induces a transient response in the visible\nspectral range near the cavity polariton resonances. We show how these optical\nresponse can be understood in terms of ultrafast heating of electrons in the\nmetal cavity mirror, which modifies the effective refractive index and\nsubsequently the strong coupling conditions. The temporal dynamics of the\nmicrocavity are strictly determined by carriers in the metal, including the\ncooling of electrons via electron-phonon coupling and excitation of propagating\ncoherent acoustic modes in the lattice. We rule out multiphoton excitation\nprocesses and verify that no real polariton population exists despite their\nstrong transient features. These results suggest the promise of cavity\npolaritons as sensitive probes of non-equilibrium phenomena."
    },
    {
        "anchor": "Electrocatalytic properties of manganese and cobalt polyporphine films\n  toward oxygen reduction reaction: Novel member of polymetalloporphines, namely manganese polymetalloporphine of\ntype I (pMnP-I) obtained by ion exchange from magnesium polyporphine of type I\n(pMgP-I) is reported for the first time and compared to its cobalt analogue\n(pCoP-I). Both polymer films have been obtained via two-step procedure:\ndemetalation of the pMgP-I electrode film via its exposure to trifluoroacetic\nacid solution, resulting in formation of the metal-free polyporphine of type I\n(pH2P-I) followed by electrochemically induced incorporation of Co or Mn ions\nfrom the acetonitrile solution of cobalt and manganese perchlorates. A further\noxidative transformation of pCoP-I, pMnP-I polymer films has led to the\ncorresponding polyporphines of type II, pCoP-II and pMnP-II, possessing such\nunique features as condensed polymer structure with a very high density of\nactive sites and high electronic conductivity within a very broad potential\nrange including the one corresponding to the neutral (uncharged) state of the\npolymer matrix. Both polymers of type II also exhibit interesting\nelectrocatalytic activity toward oxygen electroreduction in aqueous neutral (pH\n6.7) and alkaline (pH 13) media which was evaluated under cyclic voltammetric\nand steady-state conditions. The results demonstrate that the efficiency\n(regardless of the electrolyte) of both polymetalloporphines is comparable to\nbare platinum electrode. The effect of annealing of polymer-modified electrodes\non their catalytic properties has also been considered.",
        "positive": "A Comprehensive Study of $g$-Factors, Elastic, Structural and Electronic\n  Properties of III-V Semiconductors using Hybrid-Density Functional Theory: Despite the large number of theoretical III-V semiconductor studies reported\nevery year, our atomistic understanding is still limited. The limitations of\nthe theoretical approaches to yield accurate structural and electronic\nproperties on an equal footing, due to the unphysical self-interaction problem\nthat affects mainly the band gap and spin-orbit splitting (SOC) in\nsemiconductors and, in particular, III-V systems with similar magnitude of the\nband gap and SOC. In this work, we will report a consistent study of the\nstructural and electronic properties of the III-V semiconductors employing the\nscreening hybrid-DFT framework, fitting the $\\alpha$ parameters for 12\ndifferent III-V compounds, namely, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb,\nInN, InP, InAs, InSb, in order to minimize the deviation between the\ntheoretical and experimental values of the band gap and SOC. Structural\nrelaxation effects were also included. Except for AlP, whose $\\alpha = 0.127$,\nwe obtained $\\alpha$ values spreading from 0.209 to 0.343, deviating less than\n0.1 from the universal value of 0.25. Our results for the lattice parameter and\nelastic constants indicate that the fitting of the $\\alpha$ does not affect\nthose structural parameters when compared with the HSE06 functional, where\n$\\alpha = 0.25$. Our analysis of the band structure based on the\n$\\textbf{k}{\\cdot}\\textbf{p}$ method shows that the effective masses are in\nagreement with the experimental values, which can be attributed to the\nsimultaneous fitting of the band gap and SOC. Finally, we estimate the values\nof $g$-factors, extracted directly from band structure, which are close to\nexperimental results indicating that the obtained band structure produced a\nrealistic set of $\\textbf{k}{\\cdot}\\textbf{p}$ parameters."
    },
    {
        "anchor": "Mathematical Modeling of Graphite-to-Diamond Transition: The energetic evaluations of graphite-to-diamond transition by electron\nirradiation are performed. The heat conduction problem is solved for the\ndiamond synthesis when a pulse-periodic source of energy is located within a\ngraphite cylinder; time dependences of temperature and pressure are found. It\nis shown, that the temperatures and pressures implemented in graphite are\nsufficient for graphite-to-diamond transition under electron bombardment.",
        "positive": "Fluorographene: Two Dimensional Counterpart of Teflon: We report a stoichiometric derivative of graphene with a fluorine atom\nattached to each carbon. Raman, optical, structural, micromechanical and\ntransport studies show that the material is qualitatively different from the\nknown graphene-based nonstoichiometric derivatives. Fluorographene is a\nhigh-quality insulator (resistivity >10^12 Ohm per square) with an optical gap\nof 3 eV. It inherits the mechanical strength of graphene, exhibiting Young's\nmodulus of 100 N/m and sustaining strains of 15%. Fluorographene is inert and\nstable up to 400C even in air, similar to Teflon."
    },
    {
        "anchor": "Maximizing absorption and scattering by dipole particles: This is a review and tutorial paper which discusses the fundamental\nlimitations on the maximal power which can be received, absorbed, and scattered\nby an electrically small electrically polarizable particle and infinite\nperiodical arrays of such particles.",
        "positive": "Self-magnetic compensation and Exchange Bias in ferromagnetic Samarium\n  systems: For Sm(3+) ions in a vast majority of metallic systems, the following\ninteresting scenario has been conjured up for long, namely, a magnetic lattice\nof tiny self (spin-orbital) compensated 4f-moments exchange coupled (and phase\nreversed) to the polarization in the conduction band. We report here the\nidentification of a self-compensation behavior in a variety of ferromagnetic Sm\nintermetallics via the fingerprint of a shift in the magnetic hysteresis (M-H)\nloop from the origin. Such an attribute, designated as exchange bias in the\ncontext of ferromagnetic/antiferromagnetic multilayers, accords these compounds\na potential for niche applications in spintronics. We also present results on\nmagnetic compensation behavior on small Gd doping (2.5 atomic percent) in one\nof the Sm ferromagnets (viz. SmCu(4)Pd). The doped system responds like a\npseudo-ferrimagnet and it displays a characteristic left-shifted linear M-H\nplot for an antiferromagnet."
    },
    {
        "anchor": "Tuning the Electronic and Optical properties of Graphene and\n  Boron-Nitride Quantum Dots through Molecular Charge-transfer Interactions: Spin-polarized first-principles calculations have been performed to tune the\nelectronic and optical properties of graphene (G) and boron-nitride (BN)\nquantum dots (QDs) through molecular charge-transfer using\nTetracyanoquinodimethane (TCNQ) and Tetrathiafulvalene (TTF) as dopants. From\nour calculations, we find that the nature of interaction between the dopants\nand QDs is similar to the interaction between the dopants and their\ntwo-dimensional counter parts of the QDs, namely, graphene and hexagonal\nboron-nitride sheets. Based on the values of formation energy and distance\nbetween QDs and dopants, we find that both the dopants are physisorbed on the\nQDs. Also, we find that GQDs interact strongly with the dopants compared to the\nBNQDS. Interestingly, though the dopants are physisorbed on QDs, their\ninteraction lead to a decrement in the HOMO-LUMO gap of QDs by more than half\nof their original value. We have also observed a spin-polarized HOMO-LUMO gap\nin certain QD-dopant complexes. Mulliken population analysis, Density of states\n(DOS), projected DOS (pDOS) plots and optical conductivity calculations have\nbeen performed to support and understand the reasons behind the above mentioned\nfindings.",
        "positive": "Magnetic Proximity Effect in Pt/CoFe2O4 Bilayers: We observe the magnetic proximity effect (MPE) in Pt/CoFe2O4 bilayers grown\nby molecular beam epitaxy. This is revealed through angle-dependent\nmagnetoresistance measurements at 5 K, which isolate the contributions of\ninduced ferromagnetism (i.e. anisotropic magnetoresistance) and spin Hall\neffect (i.e. spin Hall magnetoresistance) in the Pt layer. The observation of\ninduced ferromagnetism in Pt via AMR is further supported by density functional\ntheory calculations and various control measurements including insertion of a\nCu spacer layer to suppress the induced ferromagnetism. In addition, anomalous\nHall effect measurements show an out-of-plane magnetic hysteresis loop of the\ninduced ferromagnetic phase with larger coercivity and larger remanence than\nthe bulk CoFe2O4. By demonstrating MPE in Pt/CoFe2O4, these results establish\nthe spinel ferrite family as a promising material for MPE and spin manipulation\nvia proximity exchange fields."
    },
    {
        "anchor": "Phase-Field Modelling of Transformation Pathways and Microstructural\n  Evolution in Multi-Principal Element Alloys: The recently developed refractory multi-principle element alloy (MPEA),\nAlMo$_{0.5}$NbTa$_{0.5}$TiZr, shows an interesting microstructure with cuboidal\nprecipitates of a disordered phase (${\\beta}$, bcc) coherently embedded in an\nordered phase (${\\beta}'$, B2) matrix, unlike the conventional Ni-based\nsuperalloys where the ordered phase (${\\gamma}'$, L12) is the precipitate phase\nand the disordered phase (${\\gamma}$, fcc) is the matrix phase. It becomes\ncritical to understand the phase transformation pathway (PTP) leading to this\nmicrostructure in order to tailor the microstructure for specific engineering\napplications. In this study, we first propose a possible PTP leading to the\nmicrostructure and employ the phase-field method to simulate microstructural\nevolution along the PTP. We then explore possible PTPs and materials parameters\nthat lead to an inverted microstructure with the ordered phase being the\nprecipitate phase and the disordered phase being the matrix phase, a\nmicrostructure similar to those observed in Ni-based superalloys. We find that\nin order to maintain the precipitates as highly discrete particles along these\nPTPs, the volume fraction of the precipitate phase needs to be smaller than\nthat of the matrix phase and the elastic stiffness of the precipitate phase\nshould be higher than that of the matrix phase.",
        "positive": "Local Density Approximation Description of Electronic Properties of\n  Wurtzite Cadmium Sulfide (w-CdS): We present calculated, electronic and related properties of wurtzite cadmium\nsulfide (w-CdS). Our ab-initio, non-relativistic calculations employed a local\ndensity functional approximation (LDA) potential and the linear combination of\natomic orbitals (LCAO). Following the Bagayoko, Zhao, and Williams (BZW)\nmethod, we solved self-consistently both the Kohn-Sham equation and the\nequation giving the ground state density in terms of the wave functions of the\noccupied states. Our calculated, direct band gap of 2.47 eV, at the point, is\nin excellent agreement with experiment. So are the calculated density of states\nand the electron effective mass. In particular, our results reproduce the peaks\nin the conduction band density of states, within the experimental\nuncertainties."
    },
    {
        "anchor": "Spin-torque switching: Fokker-Planck rate calculation: We describe a new approach to understanding and calculating magnetization\nswitching rates and noise in the recently observed phenomenon of \"spin-torque\nswitching\". In this phenomenon, which has possible applications to information\nstorage, a large current passing from a pinned ferromagnetic (FM) layer to a\nfree FM layer switches the free layer. Our main result is that the spin-torque\neffect increases the Arrhenius factor $\\exp(-E/kT)$ in the switching rate, not\nby lowering the barrier $E$, but by raising the effective spin temperature $T$.\nTo calculate this effect quantitatively, we extend Kramers' 1940 treatment of\nreaction rates, deriving and solving a Fokker-Planck equation for the energy\ndistribution including a current-induced spin torque of the Slonczewski type.\nThis method can be used to calculate slow switching rates without long-time\nsimulations; in this Letter we calculate rates for telegraph noise that are in\ngood qualitative agreement with recent experiments. The method also allows the\ncalculation of current-induced magnetic noise in CPP (current perpendicular to\nplane) spin valve read heads.",
        "positive": "Chirality-selected crystal growth and spin polarization over centimeters\n  of transition metal disilicide crystals: We performed a chirality-controlled crystal growth of transition metal\ndisilicide NbSi$_{2}$ and TaSi$_{2}$ by using a laser-diode-heated floating\nzone (LDFZ) method. The crystal chirality was evaluated in the crystals of\ncentimeters in length by performing single crystal X-ray diffraction as well as\nprobing a spin polarization originating from chirality-induced spin selectivity\n(CISS) effect. The crystals of right-handed NbSi$_{2}$ and of left-handed\nTaSi$_{2}$ were obtained in the conventional LDFZ crystal growth, while the\nleft-handed NbSi$_{2}$ and right-handed TaSi$_{2}$ crystals were grown by the\nLDFZ method with the composition-gradient feed rods. The spin polarization via\nthe CISS was observed over centimeters in the NbSi$_{2}$ single crystals and\nthe sign of the CISS signals was dependent on the chirality of crystals. The\ncorrelation between the crystal chirality and CISS signals indicates that the\nCISS measurements work as a non-destructive method for chirality determination\neven in centimeter-long specimens."
    },
    {
        "anchor": "The Spin-Orbit Torque from a Magnetic Heterostructure with High-Entropy\n  Alloy: High-entropy alloy (HEA) is a family of metallic materials with nearly equal\npartitions of five or more metals, which might possess mechanical and transport\nproperties that are different from conventional binary or tertiary alloys. In\nthis work, we demonstrate current-induced spin-orbit torque (SOT) magnetization\nswitching in a Ta-Nb-Hf-Zr-Ti HEA-based magnetic heterostructure with\nperpendicular magnetic anisotropy (PMA). The maximum damping-like SOT\nefficiency from this particular HEA-based magnetic heterostructure is further\ndetermined to be $|\\zeta^{\\operatorname{HEA}}_{DL}|\\approx0.033$ by hysteresis\nloop shift measurements, while that for the Ta control sample is\n$|\\zeta^{\\operatorname{Ta}}_{DL}|\\approx0.04$. Our results indicate that\nHEA-based magnetic heterostructures can serve as a new group of potential\ncandidates for SOT device applications.",
        "positive": "Thermal transport in crystals as a kinetic theory of relaxons: Thermal conductivity in dielectric crystals is the result of the relaxation\nof lattice vibrations described by the phonon Boltzmann transport equation.\nRemarkably, an exact microscopic definition of the heat carriers and their\nrelaxation times is still missing: phonons, typically regarded as the relevant\nexcitations for thermal transport, cannot be identified as the heat carriers\nwhen most scattering events conserve momentum and do not dissipate heat flux.\nThis is the case for two-dimensional or layered materials at room temperature,\nor three-dimensional crystals at cryogenic temperatures. In this work we show\nthat the eigenvectors of the scattering matrix in the Boltzmann equation define\ncollective phonon excitations, termed here relaxons. These excitations have\nwell defined relaxation times, directly related to heat flux dissipation, and\nprovide an exact description of thermal transport as a kinetic theory of the\nrelaxon gas. We show why Matthiessen's rule is violated, and construct a\nprocedure for obtaining the mean free paths and relaxation times of the\nrelaxons. These considerations are general, and would apply also to other\nsemiclassical transport models, such as the electronic Boltzmann equation. For\nheat transport, they remain relevant even in conventional crystals like\nsilicon, but are of the utmost importance in the case of two-dimensional\nmaterials, where they can revise by several orders of magnitude the relevant\ntime- and length-scales for thermal transport in the hydrodynamic regime."
    },
    {
        "anchor": "Water Reaction Mechanism in Metal Organic Frameworks with Coordinatively\n  Unsaturated Metal Ions: MOF-74: Water dissociation represents one of the most important reactions in\ncatalysis, essential to the surface and nano sciences [e.g., Hass et al.,\nScience, 1998, 282, 265-268; Brown et al., Science 2001, 294, 67-69; Bikondoa\net al., Nature 2005, 5, 189-192]. However, the dissociation mechanism on most\noxide surfaces is not well understood due to the experimental challenges of\npreparing surface structures and characterizing reaction pathways. To remedy\nthis problem, we propose the metal organic framework MOF-74 as an ideal model\nsystem to study water reactions. Its crystalline structure is well\ncharacterized; the metal oxide node mimics surfaces with exposed cations; and\nit degrades in water. Combining in situ IR spectroscopy and first-principles\ncalculations, we explored the MOF-74/water interaction as a function of vapor\npressure and temperature. Here, we show that, while adsorption is reversible\nbelow the water condensation pressure (~19.7 Torr) at room temperature, a\nreaction takes place at ~150 centigrades even at low water vapor pressures.\nThis important finding is unambiguously demonstrated by a clear spectroscopic\nsignature for the direct reaction using D2O, which is not present using H2O due\nto strong phonon coupling. Specifically, a sharp absorption band appears at 970\ncm-1 when D2O is introduced at above 150 centigrades, which we attribute to an\nO-D bending vibration on the phenolate linker. Although H2O undergoes a similar\ndissociation reaction, the corresponding O-H mode is too strongly coupled to\nMOF vibrations to detect. In contrast, the O-D mode falls in the phonon gap of\nthe MOF and remains localized.",
        "positive": "The laser polarization as control parameter in the pattern formation: The recently observed dependence of the periodic surface structures on the\nlight polarization in the laser induced pattern formation is analyzed within a\nmodel where the polarization induces significant deviation the spatial\ndistribution of the energy deposited by the photon from isotropic energy\ndistribution. We argue that the laser polarization breaks the rotation symmetry\non the surface and is responsible for the correlation of the surface structures\nwith the degree and the direction of polarization. Moreover it is shown that\nthe polarization induces the appearence of novel features of the surface\nmorphology and time evolution, which could be directly tested experimentally."
    },
    {
        "anchor": "Ab initio investigation of laser-induced ultrafast demagnetization of\n  L1$_0$ FePt: Intensity dependence and importance of electron coherence: We theoretically investigate the optically-induced demagnetization of\nferromagnetic FePt using the time-dependent density functional theory (TDDFT).\nWe compare the demagnetization mechanism in the perturbative and\nnonperturbative limits of light-matter interaction and show how the underlying\nmechanism of the ultrafast demagnetization depends on the driving laser\nintensity. Our calculations show that the femtosecond demagnetization in TDDFT\nis a longitudinal magnetization reduction and results from a nonlinear\noptomagnetic effect, akin to the inverse Faraday effect. The demagnetization\nscales quadratically with the electric field $E$ in the perturbative limit,\ni.e., $\\Delta M_z \\propto E^{2}$. Moreover, the magnetization dynamics happens\ndominantly at even multiples $n\\omega_0$, ($n = 0, 2, \\cdots$) of the\npump-laser frequency $\\omega_0$, whereas odd multiples of $\\omega_0$ do not\ncontribute. We further investigate the demagnetization in conjunction to the\noptically-induced change of electron occupations and electron correlations.\nCorrelations within the Kohn-Sham local-density framework are shown to have an\nappreciable yet distinct effect on the amount of demagnetization depending on\nthe laser intensity. Comparing the ${ab~initio}$ computed demagnetizations with\nthose calculated from spin occupations, we show that electronic coherence plays\na dominant role in the demagnetization process, whereas interpretations based\non the time-dependent occupation numbers poorly describe the ultrafast\ndemagnetization.",
        "positive": "Bismuth layer properties in the ultrathin Bi-FeNi multilayer films\n  probed by spectroscopic ellipsometry: Using wide-band (0.5-6.5 eV) spectroscopic ellipsometry we study ultrathin\n[Bi(0.6-2.5 nm)-FeNi(0.8,1.2 nm)]N multilayer films grown by rf sputtering\ndeposition, where the FeNi layer has a nanoisland structure and its morphology\nand magnetic properties change with decreasing the nominal layer thickness.\nFrom the multilayer model simulations of the ellipsometric angles, Psi(omega)\nand Delta(omega), the complex (pseudo)dielectric function spectra of the Bi\nlayer were extracted. The obtained results demonstrate that the Bi layer can\npossess the surface metallic conductivity, which is strongly affected by the\nmorphology and magnetic properties of the nanoisland FeNi layer in the GMR-type\nBi-FeNi multilayer structures."
    },
    {
        "anchor": "Electronic, optical and thermal properties of the hexagonal and fcc\n  Ge2Sb2Te5 chalcogenide from first-principle calculations: We present a comprehensive computational study on the properties of\nface-centered cubic and hexagonal chalcogenide Ge2Sb2Te5. We calculate the\nelectronic structure using density functional theory (DFT); the obtained\ndensity of states (DOS) compares favorably with experiments, also looking\nsuitable for transport analysis. Optical constants including refraction index\nand absorption coefficient capture major experimental features, aside from an\nenergy shift owed to an underestimate of the band gap that is typical of DFT\ncalculations. We also compute the phonon DOS for the hexagonal phase, obtaining\na speed of sound and thermal conductivity in good agreement with the\nexperimental lattice contribution. The calculated heat capacity reaches ~ 1.4 x\n106 J/(m3 K) at high temperature, in agreement with experimental data, and\nprovides insight into the low-temperature range (< 150 K), where data are\nunavailable.",
        "positive": "Pressure-dependent mechanical and thermodynamic properties of newly\n  discovered cubic Na2He: Recently for the first time a stable compound of He and Na (Na2He) is\npredicted at high pressure. We explore the pressure dependent elastic,\nmechanical and thermodynamic properties of this newly discovered Na2He by using\nab initio technique. The calculation presents good accordance between the\ntheoretical and experimental lattice parameters. Though the most stable\nstructure of Na2He is found at 300 GPa, present study ensures the mechanical\nstability of this compound up to 500 GPa. However, the Debye temperature,\nmelting temperature and minimum thermal conductivity of Na2He are also\ncalculated and discussed at different pressure."
    },
    {
        "anchor": "Reinvestigation on large perpendicular magnetic anisotropy in Fe/MgO\n  interface from first-principles approach: We investigated electronic structure and magnetic anisotropy in the Fe/MgO\ninterface of magnetic metal and dielectric insulator under the Cr layer of\nsmall electronegativity, by means of the first-principles density functional\napproach. The result indicates that the interface resonance state gets occupied\nunlike a typical rigid band picture as the number of Fe layers decreases,\nfinding large perpendicular anisotropies in the oscillating behavior for\nthickness dependence. We discuss scenarios of the two dimensional van Hove\nsingularity associated with flat band dispersions, and also the accuracies of\nanisotropy energy in comparison with the available experimental data.",
        "positive": "Enhancement of the magnetocaloric effect driven by changes in the\n  crystal structure of Al doped GGG, Gd3Ga5-xAlxO12 (0 < x < 5): The Gd3Ga5-xAlxO12 (0 < x < 5) solid solution has been prepared using ceramic\nsynthesis routes and the structural and magnetic properties investigated using\nX-ray diffraction, magnetic susceptibility, chi, and isothermal magnetisation,\nM(H), measurements. Our results indicate a contraction of the unit cell and\nmore significant antiferromagnetic interactions as x increases. Despite the\ndecrease in the magnetic polarisation on application of a field and the\ncorresponding decrease in the change in the magnetic entropy we find that\nGd3Al5O12 has a significantly higher observed (17%) and theoretical (14%) DS\nper unit mass than Gd3Ga5O12. Per unit volume the theoretical increase in DS\n(7%) is offset by the increased antiferromagnetic interactions in Gd3Al5O12.\nThe differences in DS are driven by a decrease in both the mass and density as\nAl ions replace Ga ions. These results highlight the importance of changes to\nthe crystal structure when considering materials for solid state magnetic\ncooling."
    },
    {
        "anchor": "Thermophysical and magnetic properties of p- and n-type Ti-Ni-Sn based\n  half-Heusler alloys: A total of 5 different half-Heusler alloys, two p-type and two n-type with\nthe fifth a charge compensated alloy have been designed and synthesized. The\nthermophysical properties of these alloys have been investigated in the range\n10 K to 1000 K while the magnetic behavior has been studied up to 300 K. The\nelectrical resistivity of all the alloys varies within the range 0.06 to 5\nm{\\Omega} cm indicating that they are in the degenerate semiconductor limits.\nThe temperature dependence of p-type alloys exhibits a transition from metallic\nto semiconducting behavior, typical of topological insulators. The transition\nis found to occur in the range 300 K to 500 K. The n-type and compensated\nalloys exhibit a weak metallic behavior in the complete temperature range. The\nSeebeck coefficient in the p-type alloys increases with temperature reaching a\nmaximum value of 50 microV K-1 while that of the n-type alloys increases\ncontinuously reaching a value of 45 microV K-1 at ~ 800 K. The corresponding\npower factor of the n-type alloy reaches 900 microW m-1 K-2 at ~ 900 K compared\nto a maximum of ~ 250 microW m-1 K-2 at 700 K for the p-type alloy.\nMagnetically the p-type and n-type alloys are found to be paramagnetic while\nthe compensated alloy exhibits a ferromagnetic behavior.",
        "positive": "A Computational Assessment of the Efficacy of Halides as Shape-Directing\n  Agents in Nanoparticle Growth: We report a comprehensive study of aqueous halide adsorption on nanoparticles\nof gold and palladium that addresses several limitations hampering the use of\natomistic modeling as a tool for understanding and improving wet-chemical\nsynthesis and related applications. A combination of thermodynamic modeling\nwith density functional theory (DFT) calculations and experimental data is used\nto predict equilibrium shapes of halide-covered nanoparticles as a function of\nthe chemical environment. To ensure realistic and experimentally relevant\nresults, we account for solvent effects and include a large set of vicinal\nsurfaces, several adsorbate coverages as well as decahedral particles. While\nthe observed stabilization is not significant enough to result in thermodynamic\nstability of anisotropic shapes such as nanocubes, non-uniformity in the halide\ncoverage indicates the possibility of obtaining such shapes as kinetic\nproducts. With regard to technical challenges, we show that inclusion of\nsurface-solvent interactions lead to qualitative changes in the predicted\nshape. Furthermore, accounting for non-local interactions on the functional\nlevel yields a more accurate description of surface systems."
    },
    {
        "anchor": "Exciton spectroscopy of hexagonal boron nitride using non-resonant x-ray\n  Raman scattering: We report non-resonant x-ray Raman scattering (XRS) measurements from\nhexagonal boron nitride for transferred momentum from 2 to 9\n$\\mathrm{\\AA}^{-1}$ along directions both in and out of the basal plane. A\nsymmetry-based argument, together with real-space full multiple scattering\ncalculations of the projected density of states in the spherical harmonics\nbasis, reveals that a strong pre-edge feature is a dominantly $Y_{10}$-type\nFrenkel exciton with no other \\textit{s}-, \\textit{p}-, or \\textit{d}-\ncomponents. This conclusion is supported by a second, independent calculation\nof the \\textbf{q}-dependent XRS cross-section based on the Bethe-Salpeter\nequation.",
        "positive": "Compositional Control and Optimization of Molecular Beam Epitaxial\n  Growth of (Sb2Te3)x(MnSb2Te4)y Magnetic Topological Insulators: Magnetic topological insulators such as MnBi2Te4 and MnSb2Te4 are promising\nhosts of novel physical phenomena such as quantum anomalous Hall effect and\nintrinsic axion insulator state, both potentially important for the\nimplementation in topological spintronics and error-free quantum computing. In\nthe bulk, the materials are antiferromagnetic but appropriate stacking with\nnon-magnetic layers or excess Mn in the crystal lattice can induce a net\nferromagnetic alignment. In this work we report the growth of\n(Sb2Te3)x(MnSb2Te4)y layers with varying Mn content by molecular beam epitaxy.\nThe Mn flux fraction provided during growth controls the percent of MnSb2Te4\nthat is formed in the resulting layers by a self-assembly process. Highly\ncrystalline layers with compositions varying between Sb2Te3 (y=0) and MnSb2Te4\n(x=0) were obtained. The results show that Mn incorporates as a structural\ncomponent to form MnSb2Te4, and as an impurity element both in Sb2Te3 and in\nMnSb2Te4. Two modifications of the growth conditions were implemented to\nenhance the incorporation of Mn as a structural element to form MnSb2Te4.\nAnnealing of a thin portion of the layer at the beginning of growth (pre-anneal\nstep), and increasing the growth temperature, both result in a larger percent\nof MnSb2Te4 for similar Mn flux fractions during growth. Samples having at\nleast a few percent of MnSb2Te4 layers exhibit ferromagnetic behavior likely\ndue to the excess Mn in the system which stabilizes on Sb sites as MnSb\nantisite defects."
    },
    {
        "anchor": "Curved magnonic waveguides based on domain walls: The channeling of spin waves with domain walls in ultrathin ferromagnetic\nfilms is demonstrated theoretically and through micromagnetics simulations. It\nis shown that propagating excitations localized to the wall, which appear in\nthe frequency gap of bulk spin wave modes, can be guided effectively in curved\ngeometries and can propagate in close proximity to other channels with no\nperceptible scattering or loss in coherence. For N\\'eel-type walls arising from\nan interfacial Dzyaloshinskii-Moriya interaction, the channeling is strongly\nnonreciprocal and group velocities can exceed 1 km/s in the long wavelength\nlimit for certain propagation directions.",
        "positive": "Raman study of the phonon symmetries in BiFeO$_3$ single crystals: In bismuth ferrite (BiFeO3), antiferromagnetic and ferroelectric order\ncoexist at room temperature, making it of particular interest for studying\nmagnetoelectric coupling. The mutual control of magnetic and electric\nproperties is very useful for a wide variety of applications. This has led to\nan enormous amount of research into the properties of BiFeO$_3$. Nonetheless,\none of the most fundamental aspects of this material, namely the symmetries of\nthe lattice vibrations, remains controversial.We present a comprehensive Raman\nstudy of BiFeO$_3$ single crystals with the approach of monitoring the Raman\nspectra while rotating the polarization direction of the excitation laser. Our\nmethod results in unambiguous assignment of the phonon symmetries and explains\nthe origin of the controversy in the literature. Furthermore, it provides\naccess to the Raman tensor elements enabling direct comparison with theoretical\ncalculations. Hence, this allows the study of symmetry breaking and coupling\nmechanisms in a wide range of complex materials and may lead to a noninvasive,\nall-optical method to determine the orientation and magnitude of the\nferroelectric polarization."
    },
    {
        "anchor": "Spatial Non-Uniformity in Exfoliated WS2 Single layers: Monolayers of Transition Metal Dichalcogenides (TMDs) are atomically thin\ntwo-dimensional crystals with attractive optoelectronic properties, which are\npromising for emerging applications in nanophotonics. Here, we report on the\nextraordinary spatial non-uniformity of the photoluminescence (PL) and strain\nproperties of WS2 monolayers exfoliated from the natural crystal. Specifically,\nit is shown that the edges of such monolayers exhibit remarkably enhanced PL\nintensity compared to their respective central area. A comprehensive analysis\nof the recombination channels involved in the PL process demonstrates a spatial\nnon-uniformity across the monolayer's surface and reflects on the\nnon-uniformity of the intrinsic electron density across the monolayer. Auger\nelectron imaging and spectroscopy studies complemented with PL measurements in\ndifferent environments indicate that oxygen chemisorption and physisorption are\nthe two fundamental mechanisms responsible for the observed non-uniformity. At\nthe same time Raman spectroscopy analysis shows remarkable strain variations\namong the different locations of an individual monolayer, however such\nvariations cannot be strictly correlated with the non-uniform PL emission. Our\nresults shed light on the role of the chemical bonding on the competition\nbetween exciton complexes in monolayer WS2, providing a way of engineering new\nnanophotonic functions using WS2 monolayers. It is therefore envisaged that our\nfindings could find diverse applications towards the development of TMDs-based\noptoelectronic devices.",
        "positive": "Surface collective modes in the topological insulators Bi$_2$Se$_3$ and\n  Bi$_{0.5}$Sb$_{1.5}$Te$_{3-x}$Se$_{x}$: We used low-energy, momentum-resolved inelastic electron scattering to study\nsurface collective modes of the three-dimensional topological insulators\nBi$_2$Se$_3$ and Bi$_{0.5}$Sb$_{1.5}$Te$_{3-x}$Se$_{x}$. Our goal was to\nidentify the \"spin plasmon\" predicted by Raghu and co-workers [S. Raghu, et\nal., Phys. Rev. Lett. 104, 116401 (2010)]. Instead, we found that the primary\ncollective mode is a surface plasmon arising from the bulk, free carrers in\nthese materials. This excitation dominates the spectral weight in the bosonic\nfunction of the surface, $\\chi \"(\\textbf{q},\\omega)$, at THz energy scales, and\nis the most likely origin of a quasiparticle dispersion kink observed in\nprevious photoemission experiments. Our study suggests that the spin plasmon\nmay mix with this other surface mode, calling for a more nuanced understanding\nof optical experiments in which the spin plasmon is reported to play a role."
    },
    {
        "anchor": "Magnetic dead layers in La2/3Ca1/3MnO3 thin films probed by X-ray\n  magnetic circular dichroism in reflection: Surface magnetic properties of perovskite manganites have been a recurrent\ntopic during last years since they play a major role in the implementation of\nmagnetoelectronic devices. Magneto-optical techniques, such as X-ray magnetic\ncircular dichroism, turn out to be a very efficient tool to study surface\nmagnetism due to their sensitivity to magnetic and chemical variations across\nthe sample depth. Nevertheless, the application of the sum rules for the\ndetermination of the spin magnetic moment might lead to uncertainties as large\nas 40% in case of Mn ions. To overcome this problem we present an alternative\napproach consisting of using X-ray magnetic circular dichroism in reflection\ngeometry. Fit of the data by using a computer code based in a 4X4 matrix\nformalism leads to realistic results. In particular, we show that surface and\ninterface roughness are of major relevance for a proper description of the\nexperimental data and a correct interpretation of the results. By using such an\napproach we demonstrate the presence of a narrow surface region with strongly\ndepressed magnetic properties in La2/3Ca1/3MnO3 thin films.",
        "positive": "Electron effective mass and mobility limits in degenerate perovskite\n  stannate BaSnO$_3$: The high room temperature mobility and the electron effective mass in\nBaSnO$_3$ are investigated in depth by evaluation of the free carrier\nabsorption observed in infrared spectra for epitaxial films with free electron\nconcentrations from $8.3 \\times 10^{18}$ to $7.3 \\times 10^{20}$~cm$^{-3}$.\nBoth the optical band gap widening by conduction band filling and the carrier\nscattering mechanisms in the low and high doping regimes are consistently\ndescribed employing parameters solely based on the intrinsic physical\nproperties of BaSnO$_3$. The results explain the current mobility limits in\nepitaxial films and demonstrate the potential of BaSnO$_3$ to outperform\nestablished wide band gap semiconductors also in the moderate doping regime."
    },
    {
        "anchor": "Rashba-driven anomalous Nernst conductivity of lead chalcogenide films: The presence of a finite Berry curvature $\\left(\\Omega\\left(k\\right)\\right)$\nleads to anomalous thermal effects. In this letter, we compute the coefficients\nfor the anomalous Nernst effect $\\left(ANE\\right) $ and its spin analogue, the\nspin Nernst effect $\\left(SNE\\right)$ in lead chalcogenide (\\textit{PbX};\n\\textit{X} = S, Se, Te) films. The narrow gapped \\textit{PbX} films with a\nlarge spin-orbit coupling (\\textit{soc}) offer a significant Rashba interaction\nthat gives rise to $ \\Omega\\left(k\\right) $ and the attendant anomalous thermal\nbehaviour. In presence of a temperature gradient, the $ ANE $ and $ SNE $\nestablish a thermal and spin current and are characterized by their respective\ncoefficients which acquire higher values for a stronger Rashba interaction. We\nfurther show that an extrinsic \\textit{soc} generated by an in-plane electric\nfield offers a gate-like mechanism to control (and turn-off) the anomalous\nthermal currents. Finally, we conclude by deriving the efficiency of an $ ANE\n$-driven low-temperature Carnot heat engine and demonstrate that it can be\ngainfully optimized in systems with a robust intrinsic \\textit{soc} resulting\nin low carrier effective masses.",
        "positive": "Quantum Anomalous Hall Effect in Graphene from Rashba and Exchange\n  Effects: We investigate the possibility of realizing quantum anomalous Hall effect in\ngraphene. We show that a bulk energy gap can be opened in the presence of both\nRashba spin-orbit coupling and an exchange field. We calculate the Berry\ncurvature distribution and find a non-zero Chern number for the valence bands\nand demonstrate the existence of gapless edge states. Inspired by this finding,\nwe also study, by first principles method, a concrete example of graphene with\nFe atoms adsorbed on top, obtaining the same result."
    },
    {
        "anchor": "Thermoelectric Energy Conversion: How Good Can Silicon Be?: Lack of materials which are thermoelectrically efficient and economically\nattractive is a challenge in thermoelectricity. Silicon could be a good\nthermoelectric material offering CMOS compatibility, harmlessness and cost\nreduction but it features a too high thermal conductivity. High harvested power\ndensity of 7W/cm2 at deltaT=30K is modeled based on a thin-film lateral\narchitecture of thermo-converter that takes advantage of confinement effects to\nreduce the thermal conductivity. The simulation leads to the conclusion that\n10nm thick Silicon has 10 times higher efficiency than bulk.",
        "positive": "Magnetic Domain Structure of La0.7Sr0.3MnO3 thin-films probed at\n  variable temperature with Scanning Electron Microscopy with Polarization\n  Analysis: The domain configuration of 50 nm thick La0.7SrMnO3 films has been directly\ninvestigated using scanning electron microscopy with polarization analysis\n(SEMPA), with magnetic contrast obtained without the requirement for prior\nsurface preparation. The large scale domain structure reflects a primarily\nfour-fold anisotropy, with a small uniaxial component, consistent with\nmagneto-optic Kerr effect measurements. We also determine the domain transition\nprofile and find it to be in agreement with previous estimates of the domain\nwall width in this material. The temperature dependence of the image contrast\nis investigated and compared to superconducting-quantum interference device\nmagnetometry data. A faster decrease in the SEMPA contrast is revealed, which\ncan be explained by the technique's extreme surface sensitivity, allowing us to\nselectively probe the surface spin polarization which due to the double\nexchange mechanism exhibits a distinctly different temperature dependence than\nthe bulk magnetization."
    },
    {
        "anchor": "Open-Circuit Voltage Limitation by Surface Recombination in Perovskite\n  Solar Cells: Fundamental electronic processes such as charge-carrier transport and\nrecombination play a critical role in determining the efficiency of hybrid\nperovskite solar cells. The presence of mobile ions complicates the development\nof a clear understanding of these processes as the ions may introduce\nexceptional phenomena such as hysteresis or giant dielectric constants. As a\nresult, the electronic landscape, including its interaction with mobile ions,\nis difficult to access both experimentally and analytically. To address this\nchallenge, we applied a series of small perturbation techniques including\nimpedance spectroscopy (IS), intensity-modulated photocurrent spectroscopy\n(IMPS) and intensity-modulated photovoltage spectroscopy (IMVS) to planar\n$\\mathrm{MAPbI_3}$ perovskite solar cells. Our measurements indicate that both\nelectronic as well as ionic responses can be observed in all three methods and\nassigned by literature comparison. The results reveal that the dominant\ncharge-carrier loss mechanism is surface recombination by limitation of the\nquasi-Fermi level splitting. The interaction between mobile ions and the\nelectronic charge carriers leads to a shift of the apparent diode ideality\nfactor from 0.74 to 1.64 for increasing illumination intensity, despite the\nrecombination mechanism remaining unchanged.",
        "positive": "Simulations of submonolayer Xe on Pt$(111)$: the case for a chaotic low\n  temperature phase: Molecular Dynamics simulations are reported for the structural and\nthermodynamic properties of submonolayer xenon adsorbed on the $(111)$ surface\nof platinum for temperatures up to the (apparently incipient) triple point and\nbeyond. While the motion of the atoms in the surface plane is treated with a\nstandard two-dimensional molecular dynamics simulation, the model takes into\nconsideration the thermal excitation of quantum states associated with\nsurface-normal dynamics in an attempt to describe the apparent smoothing of the\ncorrugation with increasing temperature. We examine the importance of this\nthermal smoothing to the relative stability of several observed and proposed\nlow-temperature structures. Structure factor calculations are compared to\nexperimental results in an attempt to determine the low temperature structure\nof this system. These calculations provide strong evidence that, at very low\ntemperatures, the domain wall structure of a xenon monolayer adsorbed on a\nPt$(111)$ substrate possesses a chaotic-like nature, exhibiting long-lived\nmeta-stable states with pinned domain walls, these walls having narrow widths\nand irregular shapes. This result is contrary to the standard wisdom regarding\nthis system, namely that the very low temperature phase of this system is a\nstriped incommensurate phase. We present the case for further experimental\ninvestigation of this and similar systems as possible examples of chaotic low\ntemperature phases in two dimensions."
    },
    {
        "anchor": "The Dislocation Stress Functions From the Double Curl T(3)-Gauge\n  Equation: Linearity and a Look Beyond: T(3)-gauge model of defects based on the gauge Lagrangian quadratic in the\ngauge field strength is considered. The equilibrium equation of the medium is\nfulfilled by the double curl Kroner's ansatz for stresses. The problem of\nreplication of the static edge dislocation along third axis is analysed under a\nspecial, though conventional, choice of this ansatz. The translational gauge\nequation is shown to constraint the functions parametrizing the ansatz (the\nstress functions) so that the resulting stress component $\\sigma_{3 3}$ is not\nthat of the edge defect. Another translational gauge equation with the double\ncurl differential operator is shown to reproduce both the stress functions, as\nwell as the stress tensors, of the standard edge and screw dislocations.\nNon-linear extension of the newly proposed translational gauge equation is\ngiven to correct the linear defect solutions in next orders. New gauge\nLagrangian is suggested in the Hilbert-Einstein form.",
        "positive": "Variational Density Functional Perturbation Theory for Metals: Density functional perturbation theory is a well-established method to study\nresponses of molecules and solids, especially responses to atomic displacements\nor to different perturbing fields (electric, magnetic). Like for density\nfunctional theory, the treatment of metals is delicate, due to the Fermi-Dirac\nstatistics and electronic bands crossing the Fermi energy. At zero temperature,\nthere is an abrupt transition from occupied states to unoccupied ones, usually\naddressed with smearing schemes. Also, at finite temperature, fractional\noccupations are present, and the occupation numbers may vary in response to the\nperturbation. The present work establishes the characteristics of density\nfunctional perturbation theory stemming from the underlying variational\nprinciple, in the case of metals. After briefly reviewing variational density\nfunctional theory for metals, the convexity of the entropy function of the\noccupation number is analyzed, and, at finite temperature, the benefit of\nresmearing the Fermi-Dirac broadening with the Methfessel-Paxton one is\nhighlighted. Then the variational expressions for the second-order derivative\nof the free energy are detailed, exposing the different possible gauge choices.\nThe influence of the inaccuracies in the unperturbed wavefunctions from the\nprior density functional theory calculation is studied. The whole formalism is\nimplemented in the ABINIT software package."
    },
    {
        "anchor": "Direct Observation of Unusual Interfacial Dzyaloshinskii-Moriya\n  Interaction in Graphene/NiFe/Ta Heterostructure: Graphene/ferromagnet interface promises a plethora of new science and\ntechnology. The interfacial Dzyaloshinskii Moriya interaction (iDMI) is\nessential for stabilizing chiral spin textures, which are important for future\nspintronic devices. Here, we report direct observation of iDMI in\ngraphene/Ni80Fe20/Ta heterostructure from non-reciprocity in spin-wave\ndispersion using Brillouin light scattering (BLS) technique. Linear scaling of\niDMI with the inverse of Ni80Fe20 thicknesses suggests primarily interfacial\norigin of iDMI. Both iDMI and spin-mixing conductance increase with the\nincrease in defect density of graphene obtained by varying argon pressure\nduring sputter deposition of Ni80Fe20. This suggests that the observed iDMI\noriginates from defect-induced extrinsic spin-orbit coupling at the interface.\nThe direct observation of iDMI at graphene/ferromagnet interface without\nperpendicular magnetic anisotropy opens new route in designing thin film\nheterostructures based on 2-D materials for controlling chiral spin structure\nsuch as skyrmions and bubbles, and magnetic domain-wall-based storage and\nmemory devices.",
        "positive": "Instability of Amorphous Oxide Semiconductors via Carrier-Mediated\n  Structural Transition between Disorder and Peroxide State: The excited holes occupying the valence band tail states in amorphous oxide\nsemiconductors are found to induce formation of meta-stable O$_2^{2-}$ peroxide\ndefects. The valence band tail states are at least partly characterized by the\nO-O pp{\\sigma}* molecular orbital, and the localized-hole-mediated lattice\ninstability results in the formation of the peroxide defects. Along with the\nO-O bond formation, the pp{\\sigma}* state is heightened up into the conduction\nbands, and two electrons are accordingly doped in the electronic ground state.\nThe energy barrier from the O$_2^{2-}$ peroxide state to the normal disorder\nstate is found to be 0.97 eV in hybrid density functional theory. The\nhole-mediated formation of the meta-stable peroxide defects and their\nmeta-stability is suggested as an origin of the negative bias and/or\nillumination stress instability in amorphous oxide semiconductors."
    },
    {
        "anchor": "Charge ordering and self-assembled nanostructures in a fcc Coulomb\n  lattice gas: The compositional ordering of Ag, Pb, Sb, Te ions in\n(AgSbTe$_{2}$)$_{x}$(PbTe)$_{2(1-x)}$ systems possessing a NaCl structure is\nstudied using a Coulomb lattice gas (CLG) model on a face-centered cubic (fcc)\nlattice and Monte Carlo simulations. Our results show different possible\nmicrostructural orderings. Ordered superlattice structures formed out of\nAgSbTe$_{2}$ layers separated by Pb$_{2}$Te$_{2}$ layers are observed for a\nlarge range of $x$ values. For $x=0.5$, we see an array of tubular structures\nformed by AgSbTe$_{2}$ and Pb$_{2}$Te$_{2}$ blocks. For $x=1$, AgSbTe$_{2}$ has\na body-centered tetragonal (bct) structure which is in agreement with previous\nMonte Carlo simulation results for restricted primitive model (RPM) at closed\npacked density. The phase diagram of this frustrated CLG system is discussed.",
        "positive": "Carbon-based single photon emitters in hexagonal boron nitride with\n  triplet ground state: Most single photon emitters in hexagonal boron nitride has been identified as\ncarbon-based defects. These defects, when forming a donor-acceptor pair have\nspin $S\\leq \\frac{1}{2}$. By means of density functional calculations, we show\nthat two non-adjacent carbon substitutional defects of the same type (i.e.\nC$_\\mathrm{B}$-C$_\\mathrm{B}$, and C$_\\mathrm{N}$-C$_\\mathrm{N}$), can have a\ntriplet ground state. In particular, one of such defects has a zero phonon line\nenergy of 2.5 eV, and its triplet state is nearly 0.5 eV more stable than its\nsinglet."
    },
    {
        "anchor": "High Seebeck coefficient and ultra-low lattice thermal conductivity in\n  Cs2InAgCl6: The elastic, electronic and thermoelectric properties of indium-based\ndouble-perovskite halide, Cs2InAgCl6 have been studied by first principles\nstudy. The Cs2InAgCl6 is found to be elastically stable, ductile, anisotropic\nand relatively low hard material. The calculated direct bandgap 3.67 eV by\nTB-mBJ functional fairly agrees with the experimentally measured value 3.3 eV\nbut PBE functional underestimates the bandgap by 1.483 eV. The relaxation time\nand lattice thermal conductivity have been calculated by using relaxation time\napproximation (RTA) within the supercell approach. The lattice thermal\nconductivity (\\k{appa}l) is quite low (0.2 Wm-1K-1). The quite low phonon group\nvelocity in the large weighted phase space, and high anharmonicity (large\nphonon scattering) are responsible for small \\k{appa}l. The room temperature\nSeebeck coefficient is 199 {\\mu}VK-1. Such high Seebeck coefficient arises from\nthe combination of the flat conduction band and large bandgap. We obtain power\nfactors at 300K by using PBE and TB-mBJ potentials are ~29 and ~31 mWm-1K-2,\nrespectively and the corresponding thermoelectric figure of merit of Cs2BiAgCl6\nare 0.71 and 0.72. However, the maximum ZT value obtained at 700K is ~0.74 by\nTB-mBJ potential. The obtained results implies that Cs2InAgCl6 is a promising\nmaterial for thermoelectric device applications.",
        "positive": "Classification of FIB/SEM-tomography images for highly porous multiphase\n  materials using random forest classifiers: FIB/SEM tomography represents an indispensable tool for the characterization\nof three-dimensional nanostructures in battery research and many other fields.\nHowever, contrast and 3D classification/reconstruction problems occur in many\ncases, which strongly limits the applicability of the technique especially on\nporous materials, like those used for electrode materials in batteries or fuel\ncells. Distinguishing the different components like active Li storage particles\nand carbon/binder materials is difficult and often prevents a reliable\nquantitative analysis of image data, or may even lead to wrong conclusions\nabout structure-property relationships. In this contribution, we present a\nnovel approach for data classification in three-dimensional image data obtained\nby FIB/SEM tomography and its applications to NMC battery electrode materials.\nWe use two different image signals, namely the signal of the angled SE2 chamber\ndetector and the Inlens detector signal, combine both signals and train a\nrandom forest, i.e. a particular machine learning algorithm. We demonstrate\nthat this approach can overcome current limitations of existing techniques\nsuitable for multi-phase measurements and that it allows for quantitative data\nreconstruction even where current state-of the art techniques fail, or demand\nfor large training sets. This approach may yield as guideline for future\nresearch using FIB/SEM tomography."
    },
    {
        "anchor": "Spin relaxation and coherence times for electrons at the Si/SiO2\n  interface: While electron spins in silicon heterostructures make attractive qubits,\nlittle is known about the coherence of electrons at the Si/SiO2 interface. We\nreport spin relaxation (T1) and coherence (T2) times for mobile electrons and\nnatural quantum dots at a 28Si/SiO2 interface. Mobile electrons have short T1\nand T2 of 0.3 us at 5 K. In line with predictions, confining electrons and\ncooling increases T1 to 0.8 ms at 350 mK. In contrast, T2 for quantum dots is\naround 10 us at 350 mK, increasing to 30 us when the dot density is reduced by\na factor of two. The quantum dot T2 is shorter than T1, indicating that T2 is\nnot controlled by T1 at 350 mK but is instead limited by an extrinsic\nmechanism. The evidence suggests that this extrinsic mechanism is an exchange\ninteraction between electrons in neighboring dots.",
        "positive": "Analysis of the microbond test using nonlinear fracture mechanics: Microbond tests composed of single fibre and matrix droplet are often used to\ndetermine the properties of fibre reinforced composites. Interfacial shear\nstrength is quantified by the maximum pull-out force assuming a uniform stress\ndistribution along the fibre. Here, nonlinear finite element analyses are\nperformed to investigate the validity of this assumption."
    },
    {
        "anchor": "Ultrafast Time-Resolved Faraday Rotation in EuO Thin Films: We have investigated the ultrafast spin dynamics in EuO thin films by\ntime-resolved Faraday rotation spectroscopy. The photoinduced magnetization is\nfound to be increased in a transient manner, accompanied with subsequent\ndemagnetization. The dynamical magnetization enhancement showed a maximum\nslightly below the Curie temperature with prolonged tails toward both lower and\nhigher temperatures and dominates the demagnetization counterpart at 55 K. The\nmagnetization enhancement component decays in ~1 ns. The realization of the\ntransient collective ordering is attributable to the enhancement of the f-d\nexchange interaction.",
        "positive": "Hydrogen Concentration in Photovoltaic a-Si:H Annealed at Different\n  Temperatures Measured by Neutron Reflectometry: Amorphous hydrogenated silicon (a-Si:H) is an important material for surface\ndefect passivation of photovoltaic silicon (Si) wafers in order to reduce their\nrecombination losses. The material is however unstable with regards to hydrogen\n(H) desorption at elevated temperatures, which can be an issue during\nprocessing and device manufacturing. In this work we determine the temperature\nstability of a-Si:H by structural characterization of a-Si:H/Si bilayers with\nneutron- (NR) and X-ray reflectometry (XRR) combined with photoconductance\nmeasurements yielding the minority carrer lifetime. The neutrons are sensitive\nto light elements such as H, while the X-rays which are insensitive to the\nH-concentration, provide an independent constraint on the layer structure. It\nis shown that H-desorption takes place at a temperature of approximately T =\n$425\\,^{\\circ}\\mathrm{C}$ and that hydrogen content and minority carrier\nlifetimes have a strongly correlated linear relationship, which can be\ninterpreted as one hydrogen atom passivating one defect."
    },
    {
        "anchor": "Rapid Activation of Non-Oriented Mechanophores via Shock Loading and\n  Spallation: Mechanophores, stimuli-responsive molecules that respond chromatically to\nmechanochemical reactions, are important for understanding the coupling between\nmechanics and chemistry as well as in engineering applications. However, the\natomic-level understanding of their activation originates from gas phase\nstudies or under simple linear elongation forces directly on molecules or\npolymer chains containing mechanophores. The effect of many-body distortions,\npervasive in condensed-phase applications, is not understood. Therefore, we\nperformed large-scale molecular dynamics simulations of a PMMA-spiropyran\nco-polymer under dynamic mechanical loading and studied the activation of the\nmechanophore under various conditions from dynamical compression to tension\nduring unloading. Detailed analysis of the all-atom MD trajectories shows that\nthe mechanophore blocks experience significant many-body intra-molecular\ndistortion that can significantly decrease the activation barrier as compared\nto when deformation rates are slow relative to molecular relaxation timescales.\nWe find that the reactivity of mechanophores under material compression states\nis governed by many-body effects of intra-molecular torsions, whereas under\ntension the reactions are governed by tensile stresses.",
        "positive": "Generalized Wannier Functions: We consider single particle Schrodinger operators with a gap in the en ergy\nspectrum. We construct a complete, orthonormal basis function set for the inv\nariant space corresponding to the spectrum below the spectral gap, which are\nexponentially localized a round a set of closed surfaces of monotonically\nincreasing sizes. Estimates on the exponential dec ay rate and a discussion of\nthe geometry of these surfaces is included."
    },
    {
        "anchor": "Spatial distribution of spin-wave modes in cylindrical nanowires of\n  finite aspect ratio: The spin wave modes of cylindrical nanowires of moderate diameter-to-length\nratio are investigated in this article. Based on three dimensional simulations\nand analytical calculations we determine the spatial structure of the modes. We\nshow that standing spin waves and localized edge modes form the discrete\nspectrum of the nanowires. Using a simple analytical model we infer an extended\ndispersion relation for spin waves in cylinders. Considering the variation of\nthe demagnetizing (internal) field we show that the localized dipole-exchange\nmodes at the edges are always present.",
        "positive": "Machine Learning-Based Classification, Interpretation, and Prediction of\n  High-Entropy-Alloy Intermetallic Phases: The design of high-entropy alloys (HEA) with desired properties is\nchallenging due to their large compositional space. While various machine\nlearning (ML) models can predict specific HEA solid-solution phases (SS),\npredicting high-entropy intermetallic phases (IM) is underdeveloped due to\nlimited datasets and inadequate ML features. This paper introduces feature\nengineering-assisted ML models that achieve detailed phase classification and\nhigh accuracy. By combining phase-diagram-based and physics-based features, it\nis found that the ML models trained on the Random Forest (RF) and Support\nVector Machine (SVM) regressors, are able to classify individual SS and common\nIM (Sigma, Laves, Heusler, and refractory B2 phases) with accuracies ranging\nfrom 80 - 94%. The machine-learned features also enable the interpretation of\nIM formation. Furthermore, the efficacies of the RF, SVM, and neural network\n(NN) models are critically evaluated. The phase classification accuracies are\nfound to decrease upon utilizing the NN model to train the datasets. The\naccuracy of the model prediction is validated by synthesizing 86 new alloys.\nThis approach provides a practical and robust framework for guiding HEA phase\ndesign, particularly for technologically significant IM phases."
    },
    {
        "anchor": "Unique electronic state in ferromagnetic semiconductor FeCl$_{2}$\n  monolayer: Two-dimensional (2D) van der Waals (vdW) magnetic materials could be an ideal\nplatform for ultracompact spintronic applications. Among them, FeCl$_{2}$\nmonolayer in the triangular lattice is subject to a strong debate. Thus, we\ncritically examine its spin-orbital state, electronic structure, and magnetic\nproperties, using a set of delicate first-principles calculations, crystal\nfield level analyses, and Monte Carlo simulations. Our work reveals that\nFeCl$_{2}$ monolayer is a ferromagnetic (FM) semiconductor in which the\nelectron correlation of the narrow Fe $3d$ bands determines the band gap of\nabout 1.2 eV. Note that only when the spin-orbit coupling (SOC) is properly\nhandled, the unique $d$$^{5\\uparrow}$$l$$^\\downarrow_{z+}$ electronic ground\nstate is achieved. Then, both the orbital and spin contributions (0.59\n$\\mu_{\\rm B}$ plus 3.56 $\\mu_{\\rm B}$) to the total magnetic moment well\naccount for, for the first time, the experimental perpendicular moment of 4.3\n$\\mu_{\\rm B}$/Fe. Moreover, we find that a compressive strain further\nstabilizes the $d$$^{5\\uparrow}$$l$$^\\downarrow_{z+}$ ground state, and that\nthe enhanced magnetic anisotropy and exchange coupling would boost the Curie\ntemperature ($T_{\\rm C}$) from 25 K for the pristine FeCl$_{2}$ monolayer to\n69-102 K under 3$\\%$-5$\\%$ compressive strain. Therefore, FeCl$_{2}$ monolayer\nis indeed an appealing 2D FM semiconductor.",
        "positive": "Ground state properties and high pressure behavior of plutonium dioxide:\n  Systematic density functional calculations: Plutonium dioxide is of high technological importance in nuclear fuel cycle\nand is particularly crucial in long-term storage of Pu-based radioactive waste.\nUsing first-principles density-functional theory, in this paper we\nsystematically study the structural, electronic, mechanical, thermodynamic\nproperties, and pressure induced structural transition of PuO$_{2}$. To\nproperly describe the strong correlation in the Pu $5f$ electrons, the local\ndensity approximation$+U$ and the generalized gradient approximation$+U$\ntheoretical formalisms have been employed. We optimize the $U$ parameter in\ncalculating the total energy, lattice parameters, and bulk modulus at the\nnonmagnetic, ferromagnetic, and antiferromagnetic configurations for both\nground state fluorite structure and high pressure cotunnite structure. The best\nagreement with experiments is obtained by tuning the effective Hubbard\nparameter $U$ at around 4 eV within the LDA$+U$ approach. After carefully\ntesting the validity of the ground state, we further investigate the bonding\nnature, elastic constants, various moduli, Debye temperature, hardness, ideal\ntensile strength, and phonon dispersion for fluorite PuO$_{2}$. Some\nthermodynamic properties, e.g., the Gibbs free energy, volume thermal\nexpansion, and specific heat, are also calculated. As for cotunnite phase,\nbesides the elastic constants, various moduli, and Debye temperature at 0 GPa,\nwe have further presented our calculated electronic, structural, and magnetic\nproperties for PuO$_{2}$ under pressure up to 280 GPa. A metallic transition at\naround 133 GPa and an isostructural transition in pressure range of 75-133 GPa\nare predicted."
    },
    {
        "anchor": "The impact of hysteresis on the electrocaloric effect at first-order\n  phase transitions: We study the impact of thermal hysteresis at the first-order\nstructural/ferroelectric phase transitions on the electrocaloric response in\nbulk BaTiO$_3$ by performing molecular dynamics simulations for a\nfirst-principles-based effective Hamiltonian. We demonstrate that the\nelectrocaloric response can conceptually be separated in two contributions: a\ntransitional part, stemming from the discontinuous jump in entropy at the first\norder phase transition, and a configurational part, due to the continuous\nchange of polarization and entropy within each phase. This latter part\nincreases with the strength of the applied field, but for small fields it is\nvery small. In contrast, we find a large temperature change of $\\sim 1$ K\nresulting from the transition entropy, which is essentially independent of the\nfield strength. However, due to the coexistence region close to the first order\nphase transition, this large electrocaloric response depends on the thermal\nhistory of the sample and is generally not reversible. We show that this\nirreversibility can be overcome by using larger fields.",
        "positive": "Twin interaction with $\u03a3$11 tilt grain boundaries in BCC Fe :\n  Formation of new grain boundaries: It is well known that the twinning is an important mode of plastic\ndeformation in nanocrystalline materials. As a result, it is expected that the\ntwin can interact with different grain boundaries (GBs) during the plastic\ndeformation. Understanding these twin-GB interactions is crucial for our\nunderstanding of mechanical behavior of materials. In this work, the twin\ninteraction with different $\\Sigma$11 symmetric and asymmetric tilt GBs has\nbeen investigated in BCC Fe using molecular dynamics (MD) simulations. The\nresults indicate that twin nucleate from the crack or GB and, its interaction\nwith $\\Sigma$11 asymmetric tilt GBs leads to the formation of a new GB. This\nnew GB consist of $<$100$>$ Cottrell type immobile dislocations. The detailed\natomistic mechanisms responsible for this new GB formation have been revealed\nusing atomistic simulations. Interestingly, the new GB formation has not been\nobserved in the case of twin interaction with $\\Sigma$11 symmetric tilt GBs."
    },
    {
        "anchor": "Mixed-anion mixed-cation perovskite\n  (FAPbI$_3$)$_{0.875}$(MAPbBr$_3$)$_{0.125}$: an ab-initio molecular dynamics\n  study: Mixed-anion mixed-cation perovskites with (FAPbI$_3$)$_{1-x}$(MAPbBr$_3$)$_x$\ncomposition have allowed record efficiencies in photovoltaic solar cells, but\ntheir atomic-scale behaviour is not well understood yet, in part because their\ntheoretical modelling requires consideration of complex and interrelated\ndynamic and disordering effects. We present here an ab initio molecular\ndynamics investigation of the structural, thermodynamic, and electronic\nproperties of the (FAPbI$_3$)$_{0.875}$(MAPbBr$_3$)$_{0.125}$ perovskite. A\nspecial quasi-random structure is proposed to mimic the disorder of both the\nmolecular cations and the halide anions, in a stoichiometry that is close to\nthat of one of today's most efficient perovskite solar cells. We show that the\nrotation of the organic cations is more strongly hindered in the mixed\nstructure in comparison with the pure compounds. Our analysis suggests that\nthis mixed perovskite is thermodynamically stable against phase separation\ndespite the endothermic mixing enthalpy, due to the large configurational\nentropy. The electronic properties are investigated by hybrid density\nfunctional calculations including spin-orbit coupling in carefully selected\nrepresentative configurations extracted from the molecular dynamics. Our model,\nthat is validated here against experimental information, provides a more\nsophisticated understanding of the interplay between dynamic and disordering\neffects in this important family of photovoltaic materials.",
        "positive": "Electronic properties of edge-functionalized zigzag graphene nanoribbons\n  on SiO2 substrate-v2: Based on first-principles calculations, electronic properties of\nedge-functionalized zigzag graphene nanoribbons (ZGNRs) on SiO2 substrate are\npresented. Metallic or semiconducting properties of ZGNRs are revealed due to\nvarious interactions between edge-hydrogenated ZGNRs and different SiO2 (0001)\nsurfaces. Bivalent functional groups decorating ZGNRs serve as the bridge\nbetween active edges of ZGNRs and SiO2. These functional groups stabilize ZGNRs\non substrate, as well as modify the edge states of ZGNRs and further affect\ntheir electronic properties. Band gaps are opened owing to edge states\ndestruction and distorted lattice in ZGNRs."
    },
    {
        "anchor": "Entropy and disorder enable charge separation in organic solar cells: Although organic heterojunctions can separate charges with near-unity\nefficiency and on a sub-picosecond timescale, the full details of the\ncharge-separation process remain unclear. In typical models, the Coulomb\nbinding between the electron and the hole can exceed the thermal energy\n$k_\\mathrm{B}T$ by an order of magnitude, suggesting that it is impossible for\nthe charges to separate before recombining. Here, we consider the entropic\ncontribution to charge separation in the presence of disorder and find that\neven modest amounts of disorder have a decisive effect, reducing the\ncharge-separation barrier to about $k_\\mathrm{B}T$ or eliminating it\naltogether. Therefore, the charges are usually not thermodynamically bound at\nall and could separate spontaneously if the kinetics otherwise allowed it. Our\nconclusion holds despite the worst-case assumption of localised, thermalised\ncarriers, and is only strengthened if mechanisms like delocalisation or `hot'\nstates are also present.",
        "positive": "Electronic Band Structure Effects in the Stopping of Protons in Copper: We present an ab initio study of the electronic stopping power of protons in\ncopper over a wide range of proton velocities $v = 0.02-10~\\mathrm{a.u.}$ where\nwe take into account non-linear effects. Time-dependent density functional\ntheory coupled with molecular dynamics is used to study electronic excitations\nproduced by energetic protons. A plane-wave pseudopotential scheme is employed\nto solve the time-dependent Kohn-Sham equations for a moving ion in a periodic\ncrystal. The electronic excitations and the band structure determine the\nstopping power of the material and alter the interatomic forces for both\nchanneling and off-channeling trajectories. Our off-channeling results are in\nquantitative agreement with experiments, and at low velocity they unveil a\ncrossover region of superlinear velocity dependence (with a power of $\\sim\n1.5$) in the velocity range $v = 0.07-0.3~\\mathrm{a.u.}$, which we associate to\nthe copper crystalline electronic band structure. The results are rationalized\nby simple band models connecting two separate regimes. We find that the limit\nof electronic stopping $v\\to 0$ is not as simple as phenomenological models\nsuggest and it plagued by band-structure effects."
    },
    {
        "anchor": "Prediction of stable hafnium carbides: their stoichiometries, mechanical\n  properties, and electronic structure: Hafnium carbides are studied by a systematic search for possible stable\nstoichiometric compounds in the Hf-C system at ambient pressure using\nvariable-composition ab initio evolutionary algorithm implemented in the USPEX\ncode. In addition to well-known HfC, we predicted two additional compounds\nHf3C2 and Hf6C5. The structure of Hf6C5 with space group C2/m contains 11 atoms\nin the primitive cell and this prediction revives the earlier proposal by A. I.\nGusev. The stable structure of Hf3C2 also has space group C2/m, and is more\nenergetically favorable than the Immm, P-3m1, P2 and C2221 structures put\nforward by A. I. Gusev. Dynamical and mechanical stability of the newly\npredicted structures have been verified by calculations of their phonons and\nelastic constants. The bulk and shear moduli of Hf3C2 are 195.8 GPa and 143.1\nGPa, respectively, while for Hf6C5 they are 227.9 GPa and 187.2 GPa,\nrespectively. Their mechanical properties are inferior to those of HfC due to\nthe presence of structural vacancies. Chemical bonding, band structure, and\nBader charge are presented and discussed.",
        "positive": "Different origin of the ferromagnetic order in (Ga,Mn)As and (Ga,Mn)N: The mechanism for the ferromagnetic order of (Ga,Mn)As and (Ga,Mn)N is\nextensively studied over a vast range of Mn concentrations. We calculate the\nelectronic structures of these materials using density functional theory in\nboth the local spin density approximation and the LDA+U scheme, that we have\nnow implemented in the code SIESTA.\n  For (Ga,Mn)As, the LDA+U approach leads to a hole mediated picture of the\nferromagnetism, with an exchange constant $N\\beta$ =~ -2.8 eV. This is smaller\nthan that obtained with LSDA, which overestimates the exchange coupling between\nMn ions and the As $p$ holes.\n  In contrast, the ferromagnetism in wurtzite (Ga,Mn)N is caused by the\ndouble-exchange mechanism, since a hole of strong $d$ character is found at the\nFermi level in both the LSDA and the LDA+U approaches. In this case the\ncoupling between the Mn ions decays rapidly with the Mn-Mn separation. This\nsuggests a two phases picture of the ferromagnetic order in (Ga,Mn)N, with a\nrobust ferromagnetic phase at large Mn concentration coexisting with a diluted\nweak ferromagnetic phase."
    },
    {
        "anchor": "Measurements of Growth Rates of (0001) Ice Crystal Surfaces: We present measurements of growth rates of the (0001) facet surface of ice as\na function of water vapor supersaturation over the temperature range $-2$ $\\geq\nT\\geq -40$ C. From these data we infer the temperature dependence of premelting\non the basal surface and the effects of premelting on the ice growth dynamics.\nOver this entire temperature range the growth was consistent with a simple 2D\nnucleation model, allowing a measurement of the critical supersaturation\n$\\sigma _{0}(T)$ as a function of temperature. We find that the 2D nucleation\nbarrier is substantially diminished when the premelted layer is partially\ndeveloped, as indicated by a reduced $\\sigma _{0},$ while the barrier is higher\nboth when the premelted layer is fully absent or fully developed.",
        "positive": "Dislocation scattering in a two-dimensional electron gas: A theory of scattering by charged dislocation lines in a two-dimensional\nelectron gas (2DEG) is developed. The theory is directed towards understanding\ntransport in AlGaN/GaN high-electron-mobility transistors (HEMT), which have a\nlarge number of line dislocations piercing through the 2DEG. The scattering\ntime due to dislocations is derived for a 2DEG in closed form. This work\nidentifies dislocation scattering as a mobility-limiting scattering mechanism\nin 2DEGs with high dislocation densities. The insensitivity of the 2DEG (as\ncompared to bulk) to dislocation scattering is explained by the theory."
    },
    {
        "anchor": "Three-dimensional patterning of solid microstructures through laser\n  reduction of colloidal graphene oxide in liquid-crystalline dispersions: Graphene materials and structures have become an essential part of modern\nelectronics and photovoltaics. However, despite many production methods,\napplications of graphene-based structures are hindered by high costs, lack of\nscalability and limitations in spatial patterning. Here we fabricate\nthree-dimensional functional solid microstructures of reduced graphene oxide in\na lyotropic nematic liquid crystal of graphene oxide flakes using a pulsed\nnear-infrared laser. This reliable, scalable approach is mask-free, does not\nrequire special chemical reduction agents, and can be implemented at ambient\nconditions starting from aqueous graphene oxide flakes. Orientational ordering\nof graphene oxide flakes in self-assembled liquid-crystalline phases enables\nlaser patterning of complex, three-dimensional reduced graphene oxide\nstructures and colloidal particles, such as trefoil knots, with \"frozen\"\norientational order of flakes. These structures and particles are mechanically\nrigid and range from hundreds of nanometres to millimetres in size, as needed\nfor applications in colloids, electronics, photonics and display technology.",
        "positive": "Phospholipid-Dextran with a Single Coupling Point: a Useful Amphiphile\n  for Functionalization of Nanomaterials: Nanomaterials hold much promise for biological applications, but they require\nappropriate functionalization to provide biocompatibility in biological\nenvironments. For non-covalent functionalization with biocompatible polymers,\nthe polymer must also remain attached to the nanomaterial after removal of its\nexcess to mimic the high dilution conditions of administration in vivo.\nReported here are the synthesis and utilization singly-substituted conjugates\nof dextran and a phospholipid (Dextran-DSPE) as stable coatings for\nnanomaterials. Suspensions of single walled carbon nanotubes were found not\nonly to be stable to phosphate buffered saline (PBS), serum, and a variety of\npHs after excess polymer removal, but also provide brighter photoluminescence\nthan carbon nanotubes suspended by poly(ethylene glycol)-DSPE. In addition,\nboth gold nanoparticles (AuNPs) and gold nanorods (AuNRs) were found to\nmaintain their dispersion and characteristic optical absorbance after transfer\ninto Dextran-DSPE, and were obtained in much better yield than similar\nsuspensions with PEG-phospholipid and commonly used thiol-PEG. These\nsuspensions were also stable to PBS, serum, and a variety of pHs after removal\nof excess polymer. Dextran-DSPE thus shows great promise as a general\nsurfactant material for the functionalization of a variety of nanomaterials,\nwhich could facilitate future biological applications."
    },
    {
        "anchor": "Thermoelectric signals of state transition in polycrystalline SmB6: Topological Kondo insulator SmB6 has attracted quite a lot of attentions from\ncondensed matter physics community. A number of unique electronic properties,\nincluding low- temperature resistivity anomaly, 1D electronic transport and 2D\nFermi surfaces have been observed in SmB6. Here, we report on thermoelectric\ntransport properties of polycrystalline SmB6 over a broad temperature from 300\nK to 2 K. An anomalous transition in the temperature-dependent Seebeck\ncoefficient S from S(T) ~ T-1 to S(T) ~ T was observed around 12 K. Such a\ntransition demonstrates a transition of conductivity from 3D metallic bulk\nstates to 2D metallic surface states with insulating bulk states. Our results\nsuggest that the thermotransport measurements could be used for the\ncharacterization of state transition in topological insulators.",
        "positive": "Fe/MgO/Fe (100) textured tunnel junctions exhibiting spin polarization\n  features of single crystal junctions: Crystallographic and spin polarized transport properties of (100) textured\nand (100) epitaxial Fe/MgO/Fe magnetic tunnel junctions are compared. Strong\nsimilarities in the transport properties show that structural coherence and\nmagnetic quality at the 25 nm grain scale in textured junctions are sufficient\nto issue signatures of the spin polarized transport specific to a single\ncrystal junction. This demonstrates that the lateral coherence of the Bloch\ntunneling wave function is identically limited in both systems. Our analysis\nleads to model the textured tunnel junction as a juxtaposition of nanometer\nsized single crystal junctions, placed in parallel."
    },
    {
        "anchor": "Ballistic Deposition of Nanoclusters: Nanoporous thin-films are an important class of materials, offering a way to\nobserve fundamental surface and bulk processes with particles larger than\nindividual atoms, but small enough to interact significantly with each other\nthrough mechanisms such as stress and surface mobility. In-Situ X-ray\nReflectivity and Grazing Incidence Small Angle X-Ray Scattering (GISAXS) were\nused to monitor thin-films grown from Tungsten Disilicide (WSi$_2$) and Copper\n(Cu) nanoclusters. The nanoclusters ranged in size from 2 nm to 6 nm diameter\nand were made by high-pressure magnetron sputtering via plasma-gas\ncondensation. X-Ray Reflectivity (XRR) measurements of the film at various\nstages of growth reveal that the resulting films exhibit very low density,\napproaching 15% of bulk density. This is consistent with a simple off-lattice\nballistic deposition model where particles stick at the point of first contact\nwithout further restructuring. Furthermore, there is little merging or\nsintering of the clusters in these films.",
        "positive": "Paraelectric - Ferroelectric Phase Transitions in Particles of the\n  Sphere Shape: A transition in a spheroidal particle from the paraelectric to the\nferroelectric phase as well as dynamic susceptibility are studied without\napproximation in the paraphase. It is assumed that the surface charge is\ncompensated and the boundary condition for the polarisation is P=0, i. e. with\nzero polarisation at the surface of the particle. There is an infinite number\nof resonance frequencies in the dynamic dielectric function within the\nquasistatic approximation. The paraphase properties of the dielectric response\nof the particle are discussed. The transition temperature decreases with\ndecreasing diameter d of the particles inverse quadratically. There exists such\na critical diameter that for the particles with the diameter below the critical\none the ferroelectric phase is absent. Comparison of the experiment with\ntheoretical results is carried out. Introduction of a dead layer thickness\nleads to a very good agreement of theory with the experiment for $PbTiO_{3}$\nand to a good agreement with the experimentfor $BaTiO_{3}$."
    },
    {
        "anchor": "Room temperature magnetic phase transition in an electrically-tuned van\n  der Waals ferromagnet: Finding tunable van der Waals (vdW) ferromagnets that operate at above room\ntemperature is an important research focus in physics and materials science.\nMost vdW magnets are only intrinsically magnetic far below room temperature and\nmagnetism with square-shaped hysteresis at room-temperature has yet to be\nobserved. Here, we report magnetism in a quasi-2D magnet Cr1.2Te2 observed at\nroom temperature (290 K). This magnetism was tuned via a protonic gate with an\nelectron doping concentration up to 3.8 * 10^21 cm^-3. We observed\nnon-monotonic evolutions in both coercivity and anomalous Hall resistivity.\nUnder increased electron doping, the coercivities and anomalous Hall effects\n(AHEs) vanished, indicating a doping-induced magnetic phase transition. This\noccurred up to room temperature. DFT calculations showed the formation of an\nantiferromagnetic (AFM) phase caused by the intercalation of protons which\ninduced significant electron doping in the Cr1.2Te2. The tunability of the\nmagnetic properties and phase in room temperature magnetic vdW Cr1.2Te2 is a\nsignificant step towards practical spintronic devices.",
        "positive": "Pyridine intercalated Bi$_2$Se$_3$ heterostructures: controlling the\n  topologically protected states: We use ab initio simulations to investigate the incorporation of pyridine\nmolecules (C$_5$H$_5$N) in the van der Waals gaps of Bi$_2$Se$_3$. The\nintercalated pyridine molecules increase the separation distance between the\nBi$_2$Se$_3$ quintuple layers (QLs), suppressing the parity inversion of the\nelectronic states at the $\\Gamma$-point. We find that the intercalated region\nbecomes a trivial insulator. By combining the pristine Bi$_2$Se$_3$ region with\nthe one intercalated by the molecules, we have a non-trivial/trivial\nheterojunction characterized by the presence of (topologically protected)\nmetallic states at the interfacial region. Next we apply an external\ncompressive pressure to the system, and the results are (i) a decrease on the\nseparation distance between the QLs intercalated by pyridine molecules, and\n(ii) the metallic states are shifted toward the bulk region, turning the system\nback to insulator. That is, through a suitable tuning of the external pressure\nin Bi$_2$Se$_3$, intercalated by pyridine molecules, we can control its\ntopological properties; turning-on and -off the topologically protected\nmetallic states lying at the non-trivial/trivial interface."
    },
    {
        "anchor": "Tunable intervalence charge transfer in ruthenium Prussian blue analogue\n  enables stable and efficient biocompatible artificial synapses: Emerging concepts for neuromorphic computing, bioelectronics, and\nbrain-computer interfacing inspire new research avenues aimed at understanding\nthe relationship between oxidation state and conductivity in unexplored\nmaterials. Here, we present ruthenium Prussian blue analogue (RuPBA), a mixed\nvalence coordination compound with an open framework structure and ability to\nconduct both ionic and electronic charge, for flexible artificial synapses that\nreversibly switch conductance by more than four orders of magnitude based on\nelectrochemically tunable oxidation state. Retention of programmed states is\nimproved by nearly two orders of magnitude compared to the extensively studied\norganic polymers, thus reducing the frequency, complexity and energy costs\nassociated with error correction schemes. We demonstrate dopamine detection\nusing RuPBA synapses and biocompatibility with neuronal cells, evoking\nprospective application for brain-computer interfacing. By application of\nelectron transfer theory to in-situ spectroscopic probing of intervalence\ncharge transfer, we elucidate a switching mechanism whereby the degree of mixed\nvalency between N-coordinated Ru sites controls the carrier concentration and\nmobility, as supported by DFT.",
        "positive": "Prediction of Chlorine and Fluorine Crystal Structures at High Pressure\n  Using Symmetry Driven Structure Search with Geometric Constraints: The high-pressure properties of fluorine and chlorine are not yet well\nunderstood because both are highly reactive and volatile elements, which has\nmade conducting diamond anvil cell and x-ray diffraction experiments a\nchallenge. Here we use ab initio methods to search for stable crystal\nstructures of both elements at megabar pressures. We demonstrate how symmetry\nand geometric constraints can be combined to efficiently generate crystal\nstructures that are composed of diatomic molecules. Our algorithm extends the\nsymmetry driven structure search method [Phys. Rev. B 98 (2018) 174107] by\nadding constraints for the bond length and the number of atoms in a molecule,\nwhile still maintaining generality. As a method of validation, we have tested\nour approach for dense hydrogen and reproduced the known molecular structures\nof Cmca-12 and Cmca-4. We apply our algorithm to study chlorine and fluorine in\nthe pressure range from 10--4000 GPa while considering crystal structures with\nup to 40 atoms per unit cell. We predict chlorine to follow the same series of\nphase transformations as elemental iodine from Cmca to Immm to Fm$\\bar{3}$m,\nbut at substantially higher pressures. We predict fluorine to transition from a\nC2/c to an Cmca structure at 70 GPa, to a novel orthorhombic and metallic\nstructure with P$4_2$/mmc symmetry at 2500 GPa, and finally into its cubic\nanalogue form with Pm$\\bar{3}$n symmetry at 3000 GPa."
    },
    {
        "anchor": "Emission Transfer of Interstitial Atoms Under Shock Deformation of a\n  Metal Surface: The process of anomalous transfer of interstitial atoms during impact\ndeformation of the crystal surface is described theoretically. As shown that\nsurface impact leads to the formation of a wave of inhomogeneous atomic\ndisplacements in the medium, which propagates from the surface into the depth\nof the crystal. The formation of a deformation wave leads to a change in the\ninteratomic distance at the wave front and a change in the potential energy for\ninterstitial atoms. Interstitial atoms at the front of the deformation wave\nreceive an additional impulse, which leads to an increase in their kinetic\nenergy and contributes their movement deep into the crystal.",
        "positive": "High-resolution, yet statistically relevant, analysis of damage in DP\n  steel using artificial intelligence: High performance materials, from natural bone over ancient damascene steel to\nmodern superalloys, typically possess a complex structure at the microscale.\nTheir properties exceed those of the individual components and their\nknowledge-based improvement therefore requires understanding beyond that of the\ncomponents' individual behaviour. Electron microscopy has been instrumental in\nunravelling the most important mechanisms of co-deformation and in-situ\ndeformation experiments have emerged as a popular and accessible technique.\nHowever, a challenge remains: to achieve high spatial resolution and\nstatistical relevance in combination. Here, we overcome this limitation by\nusing panoramic imaging and machine learning to study damage in a dual-phase\nsteel. This high-throughput approach not only gives us strain and\nmicrostructure dependent insights across a large area of this heterogeneous\nmaterial, but also encourages us to expand current research past interpretation\nof exemplary cases of distinct damage sites towards the less clear-cut reality."
    },
    {
        "anchor": "Topologically Nontrivial Interband Plasmons in Type-II Weyl Semimetal\n  MoTe$_2$: In many realistic topological materials, more than one kind of fermions\ncontribute to the electronic bands crossing the Fermi level, leading to various\nnovel phenomena. Here, using momentum-resolved inelastic electron scattering,\nwe investigate the plasmons and their evolution across the phase transition in\na type-II Weyl Semimetal MoTe$_2$, in which both Weyl fermions and trivial\nnonrelativistic fermions contribute to the Fermi surface in the Td phase. One\nplasmon mode in the 1T' phase at high temperature and two plasmon modes in the\ntopological T$_d$ phase at low temperature are observed. Combining with\nfirst-priciples calculations, we show that all the plasmon modes are dominated\nby the interband correlations between the inverted bands of MoTe$_2$.\nEspecially in the T$_d$ phase, since the electronic bands split due to\ninversion symmetry breaking and spin-orbit coupling, the plasmon modes manifest\nthe interband correlation between the topological Weyl fermions and the trivial\nnonrelativistic electrons. Our work emphasizes the significance of the\ninterplay between different kinds of carriers in plasmons of topological\nmaterials.",
        "positive": "Ion Beam radiation and temperature effect on Co/Si and CoO/Co/Si thin\n  films: Co and CoO thin films were deposited by magnetron sputtering in the form of\nmultilayers. They were irradiated with Ar and Si ion beams of different\nenergies and fluences. The magnetic properties were investigated."
    },
    {
        "anchor": "Crystal growth rates in supercooled atomic liquid mixtures: Crystallization is a fundamental process in materials science, providing the\nprimary route for the realization of a wide range of new materials.\nCrystallization rates are also considered to be useful probes of glass-forming\nability. At the microscopic level, crystallization is described by the\nclassical crystal nucleation and growth theories, yet in general solid\nformation is a far more complex process. In particular, the observation of\napparently different crystal growth regimes in many binary liquid mixtures\ngreatly challenges our understanding of crystallization. Here, we study by\nexperiments, theory and computer simulations the crystallization of supercooled\nmixtures of argon and krypton, showing that crystal growth rates in these\nsystems can be reconciled with existing crystal growth models only by\nexplicitly accounting for the non-ideality of the mixtures. Our results\nhighlight the importance of thermodynamic aspects in describing the crystal\ngrowth kinetics, providing a substantial step towards a more sophisticated\ntheory of crystal growth.",
        "positive": "Irreversible nucleation in molecular beam epitaxy: From theory to\n  experiments: Recently, the nucleation rate on top of a terrace during the irreversible\ngrowth of a crystal surface by MBE has been determined exactly. In this paper\nwe go beyond the standard model usually employed to study the nucleation\nprocess, and we analyze the qualitative and quantitative consequences of two\nimportant additional physical ingredients: the nonuniformity of the\nEhrlich-Schwoebel barrier at the step-edge, because of the existence of kinks,\nand the steering effects, due to the interaction between the atoms of the flux\nand the substrate. We apply our results to typical experiments of second layer\nnucleation."
    },
    {
        "anchor": "Growth kinetics and substrate stability during high-temperature\n  molecular beam epitaxy of AlN nanowires: We study the molecular beam epitaxy of AlN nanowires between 950 and 1215\n{\\deg}C, well above the usual growth temperatures, to identify optimal growth\nconditions. The nanowires are grown by self-assembly on TiN(111) films\nsputtered onto Al$_2$O$_3$. Above 1100 {\\deg}C, the TiN film is seen to undergo\ngrain growth and its surface exhibits {111} facets where AlN nucleation\npreferentially occurs. Modelling of the nanowire elongation rate measured at\ndifferent temperatures shows that the Al adatom diffusion length is maximised\nat 1150 {\\deg}C, which appears to be the optimum growth temperature. However,\nanalysis of the nanowire luminescence shows a steep increase in the deep-level\nsignal already above 1050 {\\deg}C, associated with O incorporation from the\nAl$_2$O$_3$ substrate. Comparison with AlN nanowires grown on Si, MgO and SiC\nsubstrates suggests that heavy doping of Si and O by interdiffusion from the\nTiN/substrate interface increases the nanowire internal quantum efficiency,\npresumably due to the formation of a SiN$_x$ or AlO$_x$ passivation shell. The\noutdiffusion of Si and O would also cause the formation of the inversion\ndomains observed in the nanowires. It follows that for optoelectronic and\npiezoelectric applications, optimal AlN nanowire ensembles should be prepared\nat 1150 {\\deg}C on TiN/SiC substrates and will require an ex situ surface\npassivation.",
        "positive": "The Nuts and Bolts of Ab-Initio Core-Hole Simulations for K-shell X-Ray\n  Photoemission and Absorption Spectra: X-ray photoemission (XPS) and Near Edge X-ray Absorption Fine Structure\n(NEXAFS) spectroscopy play an important role in investigating the structure and\nelectronic structure of materials and surfaces. Ab-initio simulations provide\ncrucial support for the interpretation of complex spectra containing\noverlapping signatures. Approximate core-hole simulation methods based on\nDensity Functional Theory such as the Delta-Self-Consistent-Field ($\\Delta$SCF)\nmethod or the transition potential (TP) method are widely used to predict\nK-shell XPS and NEXAFS signatures of organic molecules, inorganic materials and\nmetal-organic interfaces at reliable accuracy and affordable computational\ncost. We present the numerical and technical details of our variants of the\n$\\Delta$SCF and transition potential method (coined $\\Delta$IP-TP) to simulate\nXPS and NEXAFS transitions. Using exemplary molecules in gas-phase, in bulk\ncrystals, and at metal-organic interfaces, we systematically assess how\npractical simulation choices affect the stability and accuracy of simulations.\nThese include the choice of exchange-correlation functional, basis set, the\nmethod of core-hole localization, and the use of periodic boundary conditions.\nWe particularly focus on the choice of aperiodic or periodic description of\nsystems and how spurious charge effects in periodic calculations affect the\nsimulation outcomes. For the benefit of practitioners in the field, we discuss\nsensible default choices, limitations of the methods, and future prospects."
    },
    {
        "anchor": "The electronic structure formation of CuxTiSe2 in a wide range (0.04 < x\n  < 0.8) of copper concentration: An experimental study of the electronic structure of copper intercalated\ntitanium dichalcogenides in a wide range of copper concentrations (x = 0.05 -\n0.6) using the x-rays photoemission spectroscopy, resonant photoemission and\nx-rays absorption spectroscopy has been performed. Negative energy shifts of\nthe Ti 2p and Se 3d core levels spectra and a corresponding decrease of the\nphoton energy in Ti 2p absorption spectra with increasing concentration of\ncopper have been found. Such sign-anomalous shifts may be explained by the\nshielding effect of the corresponding atomic shells as a result of the dynamic\ncharge transfer during the formation of a covalent chemical bond between the\ncopper atoms and the TiSe2 matrix.",
        "positive": "The effect of the buffer layer coupling on the lattice parameter of\n  epitaxial graphene on SiC(0001): Grazing incidence X-ray diffraction (GID) was employed to probe the structure\nof atomically thin carbon layers on SiC(0001): a so-called buffer layer (BL)\nwith a $6(\\sqrt{3}\\times\\sqrt{3})$R30$^\\circ$ periodicity, a monolayer graphene\n(MLG) on top of the BL, and a bilayer graphene (BLG). The GID analysis was\ncomplemented by Raman spectroscopy. The lattice parameter of each layer was\nmeasured with high precision by GID. The BL possesses a different lattice\nparameter and corrugation when it is uncovered or beneath MLG. Our results\ndemonstrate that the interfacial BL is the main responsible for the strain in\nMLG. By promoting its decoupling from the substrate via intercalation, it turns\ninto graphene, leading to a simultaneous relaxation of the MLG and formation of\na quasi-free-standing BLG."
    },
    {
        "anchor": "Composition dependent magnetic properties of iron oxide - polyaniline\n  nanoclusters: Gamma - Iron Oxide prepared by sol -gel process was used to produce\nnanocomposites with polyaniline of varying aniline concentrations. TEM shows\nthe presence of chain like structure for lower polyaniline concentration. The\nroom temperature hysteresis curves show finite coercivity of 160 Oe for all the\ncomposites while the saturation magnetization was found to decrease with\nincreasing polymer content. ZFC - FC magnetisation measurements indicate high\nblocking temperatures. It is believed that this indicates a strongly\ninteracting system, which is also shown by our TEM results. Monte Carlo\nsimulations performed on a random anisotropy model with dipolar and exchange\ninteactions match well with experimental results.",
        "positive": "Clarifying multiple-tip effects on Scanning Tunneling Microscopy imaging\n  of 2D periodic objects and crystallographic averaging in the spatial\n  frequency domain: Crystallographic image processing (CIP) techniques may be utilized in\nscanning probe microscopy (SPM) to glean information that has been obscured by\nsignals from multiple probe tips. This may be of particular importance for\nscanning tunneling microscopy (STM) and requires images from a sample that is\nperiodic in two dimensions. The image-forming current for multiple tips in STM\nis derived in a more straightforward manner than prior approaches. The Fourier\nspectrum of the current for p4mm Bloch surface wave functions and a pair of\ndelta function tips reveals the tip-separation dependence of various types of\nimage obscurations. In particular our analyses predict that quantum\ninterference should be visible on a macroscopic scale in the form of bands\nquite distinct from the basket-weave patterns a purely classical model would\ncreate at the same periodic double STM tip separations. A surface wave function\nthat models the essential character of highly (0001) oriented pyrolytic\ngraphite (technically known as HOPG) is introduced and used for a similar\ntip-separation analysis. Using a bonding H_2 tip wave function with significant\nspatial extent instead of this pair of infinitesimal Dirac delta function tips\ndoes not affect these outcomes in any observable way. This is explained by\nPierre Curie's well known symmetry principle. Classical simulations of multiple\ntip effects in STM images may be understood as modeling multiple tip effects in\nimages that were recorded with other types of SPMs). Our analysis clarifies why\nCIP and crystallographic averaging work well in removing the effects of a blunt\nSPM tip (that consist of multiple mini-tips) from the recorded 2D periodic\nimages and also outlines the limitations of this image processing techniques\nfor certain spatial separations of STM mini-tips."
    },
    {
        "anchor": "Bonding Charge Density and Ultimate Strength of Monolayer Transition\n  Metal Dichalcogenides: Two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs)\ncan withstand a large deformation without fracture or inelastic relaxation,\nmaking them attractive for application in novel strain-engineered and flexible\nelectronic and optoelectronic devices. In this study, we characterize the\nmechanical response of monolayer group VI TMDs to large elastic deformation\nusing first-principles density functional theory calculations. We find that the\nultimate strength and the overall stress response of these 2D materials is\nstrongly influenced by their chemical composition and loading direction. We\ndemonstrate that differences in the observed mechanical behavior can be\nattributed to the spatial redistribution of the occupied hybridized electronic\nstates in the region between the transition metal atom and the chalcogens. In\nspite of the strong covalent bonding between the transition metal and the\nchalcogens, we find that a simple linear relationship can be established to\ndescribe the dependence of the mechanical strength on the charge transfer from\nthe transition metal atom to the chalcogens.",
        "positive": "Symmetry-enforced band crossings in trigonal materials: Accordion states\n  and Weyl nodal lines: Nonsymmoprhic symmetries, such as screw rotations or glide reflections, can\nenforce band crossings within high-symmetry lines or planes of the Brillouin\nzone. When these band degeneracies are close to the Fermi energy, they can give\nrise to a number of unusual phenomena: e.g., anomalous magnetoelectric\nresponses, transverse Hall currents, and exotic surface states. In this paper,\nwe present a comprehensive classification of such nonsymmorphic band crossings\nin trigonal materials with strong spin-orbit coupling. We find that in trigonal\nsystems there are two different types of nonsymmorphic band degeneracies: (i)\nWeyl points protected by screw rotations with an accordion-like dispersion, and\n(ii) Weyl nodal lines protected by glide reflections. We report a number of\nexisting materials, where these band crossings are realized near the Fermi\nenergy. This includes Cu2SrSnS4 and elemental tellurium (Te), which exhibit\naccordion Weyl points; and the tellurium-silicon clathrate Te16Si38, which\nshows Weyl nodal lines. The ab-initio band structures and surface states of\nthese materials are studied in detail, and implications for experiments are\nbriefly discussed."
    },
    {
        "anchor": "Large Family of Two-Dimensional Ferroelectric Metals Discovered via\n  Machine Learning: Ferroelectricity and metallicity are usually believed not to coexist because\nconducting electrons would screen out static internal electric fields. In 1965,\nAnderson and Blount proposed the concept of 'ferroelectric metal', however, it\nis only until recently that very rare ferroelectric metals were reported. Here,\nby combining high-throughput ab initio calculations and data-driven machine\nlearning method with new electronic orbital based descriptors, we\nsystematically investigated a large family (2,964) of two-dimensional (2D)\nbimetal phosphates, and discovered 60 stable ferroelectrics with out-of-plane\npolarization, including 16 ferroelectric metals and 44 ferroelectric\nsemiconductors that contain seven multiferroics. The ferroelectricity origins\nfrom spontaneous symmetry breaking induced by the opposite displacements of\nbimetal atoms, and the full-d-orbital coinage metal elements cause larger\ndisplacements and polarization than other elements. For 2D ferroelectric\nmetals, the odd electrons per unit cell without spin polarization may lead to a\nhalf-filled energy band around Fermi level and is responsible for the\nmetallicity. It is revealed that the conducting electrons mainly move on a\nsingle-side surface of the 2D layer, while both the ionic and electric\ncontributions to polarization come from the other side and are vertical to the\nabove layer, thereby causing the coexistence of metallicity and\nferroelectricity. Van der Waals heterostructures based on ferroelectric metals\nmay enable the change of Schottky barrier height or the Schottky-Ohmic contact\ntype and induce a dramatic change of their vertical transport properties. Our\nwork greatly expands the family of 2D ferroelectric metals and will spur\nfurther exploration of 2D ferroelectric metals.",
        "positive": "Characterization and control of ZnGeN2 cation lattice ordering: ZnGeN2 and other heterovalent ternary semiconductors have important potential\napplications in optoelectronics, but ordering of the cation sublattice, which\ncan affect the band gap, lattice parameters, and phonons, is not yet well\nunderstood. Here the effects of growth and processing conditions on the\nordering of the ZnGeN2 cation sublattice were investigated using x-ray\ndiffraction and Raman spectroscopy. Polycrystalline ZnGeN2 was grown by\nexposing solid Ge to Zn and NH3 vapors at temperatures between 758 degree C and\n914 degree C. Crystallites tended to be rod-shaped, with growth rates higher\nalong the c-axis. The degree of ordering, from disordered, wurtzite-like x-ray\ndiffraction spectra to orthorhombic, with space group Pna21, increased with\nincreasing growth temperature, as evidenced by the appearance of superstructure\npeaks and peak splittings in the diffraction patterns. Annealing disordered,\nlow-temperature-grown ZnGeN2 at 850 degree C resulted in increased cation\nordering. Growth of ZnGeN2 on a liquid Sn-Ge-Zn alloy at 758 degree C showed an\nincrease in the tendency for cation ordering at a lower growth temperature, and\nresulted in hexagonal platelet-shaped crystals. The trends shown here may help\nto guide understanding of the synthesis and characterization of other\nheterovalent ternary nitride semiconductors as well as ZnGeN2."
    },
    {
        "anchor": "Defect Engineering for Modulating the Trap States in Two-dimensional\n  Photoconductor: Defect induced trap states are essential in determining the performance of\nsemiconductor photodetectors. The de-trap time of carriers from a deep trap\ncould be prolonged by several orders of magnitude as compared to shallow trap,\nresulting in additional decay/response time of the device. Here, we demonstrate\nthat the trap states in two-dimensional ReS2 could be efficiently modulated by\ndefect engineering through molecule decoration. The deep traps that greatly\nprolong the response time could be mostly filled by Protoporphyrin (H2PP)\nmolecules. At the same time, carrier recombination and shallow traps would\nin-turn play dominant roles in determining the decay time of the device, which\ncan be several orders of magnitude faster than the as-prepared device.\nMoreover, the specific detectivity of the device is enhanced (as high as ~1.89\nx 10^13 Jones) due to the significant reduction of dark current through charge\ntransfer between ReS2 and molecules. Defect engineering of trap states\ntherefore provides a solution to achieve photodetectors with both high\nresponsivity and fast response.",
        "positive": "Stress induced stripe formation in Pd/W(110): A stress-induced stripe phase of submonolayer Pd on W(110) is observed by\nlow-energy electron microscopy. The temperature dependence of the pattern is\nexplained by the change both in the boundary free energy and elastic relaxation\nenergy due to the increasing boundary width. The stripes are shown to disorder\nwhen the correlation length of the condensed phase becomes comparable to its\nperiod, while the condensate to lattice-gas transition takes place at a higher\ntemperature, as revealed by low-energy electron diffraction."
    },
    {
        "anchor": "Growth Techniques for Bulk ZnO and Related Compounds: ZnO bulk crystals can be grown by several methods. 1) From the gas phase,\nusually by chemical vapor transport. Such CVT crystals may have high chemical\npurity, as the growth is performed without contact to foreign material. The\ncrystallographic quality is often very high (free growth). 2) From melt fluxes\nsuch as alkaline hydroxides or other oxides (MoO3, V2O5, P2O5, PbO) and salts\n(PbCl2, PbF2). Melt fluxes offer the possibility to grow bulk ZnO under mild\nconditions (<1000 deg. C, atmospheric pressure), but the crystals always\ncontain traces of solvent. The limited purity is a severe drawback, especially\nfor electronic applications. 3) From hydrothermal fluxes, usually alkaline\n(KOH, LiOH) aqueous solutions beyond the critical point. Due to the amphoteric\ncharacter of ZnO, the supercritical bases can dissolve it up to several per\ncent of mass. The technical requirements for this growth technology are\ngenerally hard, but this did not hinder its development as the basic technique\nfor the growth of {\\alpha}-quartz, and meanwhile also of zinc oxide, during the\nlast decades. 4) From pure melts, which is the preferred technology for\nnumerous substances applied whenever possible, e.g. for the growth of silicon,\ngallium arsenide, sapphire, YAG. The benefits of melt growth are (i) the high\ngrowth rate and (ii) the absence of solvent related impurities. In the case of\nZnO, however, it is difficult to find container materials that are compatible\nfrom the thermal (fusion point Tf = 1975 deg. C) and chemical (required oxygen\npartial pressure) point of view. Either cold crucible (skull melting) or\nBridgman (with reactive atmosphere) techniques were shown to overcome the\nproblems that are inherent to melt growth. Reactive atmospheres allow to grow\nnot only bulk ZnO single crystals, but also other TCOs such as {\\beta}-Ga2O3\nand In2O3.",
        "positive": "Resonant optical control of the structural distortions that drive\n  ultrafast demagnetization in Cr$_2$O$_3$: We study how the color and polarization of ultrashort pulses of visible light\ncan be used to control the demagnetization processes of the antiferromagnetic\ninsulator Cr$_2$O$_3$. We utilize time-resolved second harmonic generation\n(SHG) to probe how changes in the magnetic and structural state evolve in time.\nWe show that, varying the pump photon-energy to excite either localized\ntransitions within the Cr or charge transfer states, leads to markedly\ndifferent dynamics. Through a full polarization analysis of the SHG signal,\nsymmetry considerations and density functional theory calculations, we show\nthat, in the non-equilibrium state, SHG is sensitive to {\\em both} lattice\ndisplacements and changes to the magnetic order, which allows us to conclude\nthat different excited states couple to phonon modes of different symmetries.\nFurthermore, the spin-scattering rate depends on the induced distortion,\nenabling us to control the timescale for the demagnetization process. Our\nresults suggest that selective photoexcitation of antiferromagnetic insulators\nallows fast and efficient manipulation of their magnetic state."
    },
    {
        "anchor": "Following enhanced Sm spin projection in Gd$_x$Sm$_{1-x}$N: The rare-earth nitrides form a series of structurally simple $intrinsic$\nferromagnetic semiconductors, a rare class of both fundamental interest and\napplication potential. Within the series there is a wide range of magnetic\nproperties relating to the spin/orbit contributions to the ferromagnetic ground\nstates. We report an x-ray magnetic circular dichroism investigation of the\nspin/orbit magnetic dipole alignments of Sm and Gd ions in epitaxial\nGd$_x$Sm$_{1-x}$N films. The Sm spin-alignment expectation value $\\langle S_{z}\n\\rangle$ is seen to be strengthened by the Gd/Sm exchange interaction,\nproviding guidance concerning the composition for an angular momentum\ncompensation point (where the volume-averaged total angular momentum of a film\nis zero).",
        "positive": "Tungsten Boride: a 2D Multiple Dirac Semimetal for Hydrogen Evolution\n  Reaction: Here, we propose a two-dimensional tungsten boride (WB4) lattice, with the\nGibbs free energy for the adsorption of atomic hydrogen, tending to be the\nideal value of 0 eV at 3% strained state, to host a better hydrogen evolution\nreaction activity. Based on first-principles calculations, it is demonstrated\nthat the multiple d-p-pi and d-p-sigma Dirac conjugations of WB4 lattice\nensures its excellent electronic transport characteristics. Meanwhile, coupling\nwith the d-orbitals of W, the p-orbitals of borophene subunits in WB4 lattice\ncan modulate the d band center to get a good HER performance. Our results not\nonly provide a versatile platform for hosting multiple Dirac semimetal states\nwith a sandwich configuration, but also offer a guiding principle for\ndiscovering the relationship between intrinsic properties of the active centre\nand the catalytic activity of metal layer from the emerging field of\nlow-dimensional noble-metal-free lattices."
    },
    {
        "anchor": "Ferroelectric switched all-metallic-oxide $p$-$n$ junctions: We report the first formation of the metallic $p$-$n$ junctions, the\nferroelectric (Ba,Sr)TiO$_3$ (BST) switched optimally electron-doped ($n$-type)\nmetallic T'-phase superconductor, (La,Ce)$_2$CuO$_4$ (LCCO), and hole-doped\n($p$-type) metallic CMR manganite (La,Sr)MnO$_3$ (LSMO) junctions. In contrast\nwith the previous semiconductor $p$-$n$ ($p$-$I$-$n$) junctions which are\nswitched by the built-in field $V_0$, the present metallic oxides $p$-$I$-$n$\njunctions are switched by double barrier fields, the built-in field $V_0$, and\nthe ferroelectric reversed polarized field $V_{rp}$, both take together to lead\nthe junctions to possess definite parameters, such as definite negligible\nreversed current ($10^{-9}$ A), large breakdown voltage ($>$7 V), and ultrahigh\nrectification ($>2\\times10^4$) in the bias voltage 1.2 V to 2.0 V and\ntemperature range from 5 to over 300 K. The related transport feature, barrier\nsize effect, and temperature effect are also observed and defined.",
        "positive": "Ultra-small (r<2 nm), stable (>1 year), mixed valence copper oxide\n  quantum dots with anomalous band gap: Ultra-small (r<2 nm) semiconductor quantum dots (QDs) have attracted\nattention for applications ranging from dye sensitized solar cells to sensing\ndue to its tunable electronic structure and band gap, and large specific\nsurface area. However obtaining monodisperse QDs and stabilization in this size\nregime remains a challenge. A recent report on digestive ripening of an oxide\nsystem showed substantial promise in addressing these requirements of QDs. In\nthis work, we report a green solution, soft chemical (chimie douce) approach\nfor synthesis of quasi-spherical, ultra-small, stable, and monodispersed copper\noxide QDs (r<2 nm) based on digestive ripening (DR). It may be noted this is\nonly the second transition metal oxide system in which DR is reported so far.\nDR involves the refluxing of polydispersed colloidal nanoparticles in the\npresence of surface active agents (e.g. triethanolamine (TEA)) that leads to\nfairly monodispersed nanoparticles. It has been noticed that capping with TEA\nresults in reduction in the average particle diameter from 6 +/- 4 nm to 2.4\n+/- 0.5 nm and an increase of zeta potential ({\\xi}) from +12 +/- 2 mV to +31\n+/- 2 mV. These copper oxide QDs are monodispersed (size ~ 2.4 +/- 0.5 nm), and\nstable (>1 year). In addition, these quantum dots show an anomalous increase in\nband gap (5.3 eV), inexplicable using Brus' equation. XPS indicates that Cu\nexists in mixed valence state in this material. Based on our observations, we\nsuggest that off-stoichiometry in copper oxide, which is seemingly substantial\nat these length scales, is responsible for the observed anomaly in band gap."
    },
    {
        "anchor": "Antiferromagnetic Coupling between Surface and Bulk Magnetization and\n  Anomalous Magnetic Transport in Electro-deposited Co Film: We report an interesting magnetic behavior of a Co film (thickness ~ 350\n{\\AA}) grown on Si/Ti/Cu buffer layer by electro-deposition (ED) technique.\nUsing depth sensitive X-ray reflectivity and polarized neutron reflectivity\n(PNR) we observed two layer structures for the Co film grown by ED with a\nsurface layer (thickness ~ 100 {\\AA}) of reduced density (~ 68% of bulk)\ncompared to rest of the Co film (thickness ~ 250 {\\AA}). The two layer\nstructure is consistent with the histogram profile obtained from atomic force\nmicroscope (AFM) of the film. Interestingly, using PNR, we found that the\nmagnetization in the surface Co layer is inversely (antiferomagnetically)\ncoupled (negative magnetization for surface Co layer) with the rest of the Co\nlayer for the ED grown film. While we compare PNR result for a Co film of\nsimilar layered structure grown by sputtering, the film showed a uniform\nmagnetization as expected. We also show that the depth dependent unusual\nmagnetic behavior of ED grown Co film may be responsible for anomalous\nanisotropic magnetoresistance observed in low field in this film as compared to\nthe Co film grown by sputtering. Combining X-ray scattering, AFM,\nsuperconducting quantum interface device magnetometry (SQUID), PNR and\nmagneto-transport measurements we attempted to correlate and compare the\nstructural, magnetic and morphological properties with magneto-transport of Co\nfilms grown by ED and sputtering. The study indicates that the interesting\nsurface magnetic property and magneto-transport property of the ED film is\ncaused by its unique surface morphology.",
        "positive": "Significant low lattice thermal conductivity and potential high\n  thermoelectric figure of merit in Na$_2$MgSn: Thermoelectric materials enables the harvest of waste heat and directly\nconversion into electricity. In search of high efficient thermoelectric\nmaterials, low thermal conductivity of a material is essential and critical.\nHere, we have theoretically investigated the lattice thermal conductivity and\nthermoelectric properties of layered intermetallic Na$_2$MgSn and Na$_2$MgPb\nbased on the density functional theory and linearized Boltzmann equation with\nthe single-mode relaxation-time approximation. It is found that both materials\nexhibit very low and anisotropic intrinsic lattice thermal conductivity.\nDespite of the very low mass density and simple crystal structure of\nNa$_2$MgSn, its lattice thermal conductivities along $a$ and $c$ axes are only\n1.75 and 0.80 W/m$\\cdot$K respectively at room temperatures. When Sn is\nreplaced by the heavier element Pb, its lattice thermal conductivities decrease\nremarkably to 0.51 and 0.31 W/m$\\cdot$K respectively along $a$ and $c$ axes at\nroom temperatures. We show that the low lattice thermal conductivities of both\nmaterials are mainly due to their very short phonon lifetimes, which are\nroughly between 0.4 to 4.5 ps. Combined with previous experimental\nmeasurements, the metallic Na$_2$MgPb can not be a good thermoelectric\nmaterial. However, we predict that the semiconducting Na$_2$MgSn is a potential\nroom-temperature thermoelectric material with a considerable $ZT$ of 0.34 at\n300 K. Our calculations not only imply that the intermetallic Na$_2$MgSn is a\npotential thermoelectric material, but also can motivate more theoretical and\nexperimental works on the thermoelectric researches in simple layered\nintermetallic compounds."
    },
    {
        "anchor": "Magnetic-field effects in defect-controlled ferromagnetic Ga_{1-x}Mn_xAs\n  semiconductors: We have studied the magnetic-field and concentration dependences of the\nmagnetizations of the hole and Mn subsystems in diluted ferromagnetic\nsemiconductor Ga_{1-x}Mn_xAs. A mean-field approximation to the hole-mediated\ninteraction is used, in which the hole concentration p(x) is parametrized in\nterms of a fitting (of the hole effective mass and hole/local moment coupling)\nto experimental data on the Tc critical temperature. The dependence of the\nmagnetizations with x, for a given temperature, presents a sharply peaked\nstructure, with maxima increasing with applied magnetic field, which indicates\nthat application to diluted-magnetic-semiconductor devices would require\nquality-control of the Mn-doping composition. We also compare various\nexperimental data for Tc(x) and p(x) on different Ga_{1-x}Mn_xAs samples and\nstress the need of further detailed experimental work to assure that the\nexperimental measurements are reproducible.",
        "positive": "Surface resistivity of hydrogenated amorphous carbon films: Existence of\n  intrinsic graphene on its surface: Surface resistivity of hydrogenated amorphous carbon films was measured as a\nfunction of the applied electrical field. The measured dependence shows a sharp\nambipolar peak near zero gate voltage. Furthermore, we found that in some\nsamples sheet resistance at the peak is as low as 7.5 k{\\Omega}/sq. This value\nis the same order of magnitude as the sheet resistance of a defect free\ngraphene monolayer. Therefore a conclusion is made that an intrinsic graphene\nwith dimensions of at least millimeters exist on the surface of amorphous\ncarbon films. These results can open new perspectives not only for graphene\napplications, but also for better understanding of this unique material."
    },
    {
        "anchor": "Neutral-dangling bond depletion in a-SiN films caused by magnetic\n  rare-earth elements: Amorphous silicon-nitrogen thin films doped with rare-earth elements\n(a-SiN:RE; RE = Y, La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Yb, and Lu) have been\nprepared by co-sputtering and studied by means of electron spin resonance\n(ESR). It was found that the neutral dangling-bond density [D0] of a-SiN films\ndecreases with the presence of magnetic REs and the drop of [D0] approximately\nscales with the spin and/or the de Gennes factor of each rare-earth element.\nThese results suggest that a strong exchange-like interaction,\nH=J(RE-D0)S(RE).S(D0), between the spin of the magnetic REs and D0 may be\nresponsible for this behaviour, similarly to the decrease of Tc in RE-doped\nsuperconductors.",
        "positive": "Third order nonlinear transport properties in topological chiral\n  antiferromagnetic semimetal CoNb3S6: The topology between Bloch states in reciprocal space has attracted\ntremendous attention in recent years. The quantum geometry of the band\nstructure is composed of quantum metric as real part and berry curvature as\nimaginary part. While the Berry curvature, the Berry curvature dipole and Berry\nconnection polarizability have been recently revealed by the first order\nanomalous hall, second order and third order nonlinear Hall effect\nrespectively, the quantum metric induced second order nonlinear transverse and\nlongitudinal response in topological antiferromagnetic material MnBi2Te4 was\nonly very recently reported. Here we demonstrate the similar third order\nnonlinear transport properties in the topological antiferromagnetic CoNb3S6. We\nobserved that the third order nonlinear longitudinal V3{\\omega} xx increase\nsignificantly at the antiferromagnetic transition temperature TN ~ 29 K, which\nwas probably induced by the quantum metric without time-reversal symmetry or\ninversion symmetry. Besides, temperature-dependent nonlinear behaviour was\nobserved in the first order I-V curve below the Neel temperature TN, which was\nnot reported in MnBi2Te4 and FeSn. Such nonlinear I-V behaviour hints for the\npossible existence of Charge Density Wave (CDW) state, which has been\ndiscovered in its sister material FeNb3S6. Simultaneously, two plateaus in the\nthird order nonlinear longitudinal V3{\\omega} xx~ I^{\\omega} curve are\nobserved, which is also speculated to be related with the possible CDW state.\nHowever, the genuine mechanism for the first order nonlinear I-V and its\nrelation with the third order nonlinear transport call for more experimental\ninvestigations and theoretical interpretation. Our work provides a way to\nexplore third harmonic nonlinear transport and interaction with magnetic order\nand CDW."
    },
    {
        "anchor": "Thermodynamic Modelling of Phase Equilibrium in Nanoparticles-Nematic\n  Liquid Crystals Composites: In this work, a theoretical study of phase equilibrium in mixtures of a\ncalamitic nematic liquid crystal and hard spherical nanoparticles is presented.\nA mean-field thermodynamic model is used, where the interactions are considered\nto be proportional to the number of contacts, which in turn are proportional to\nthe areas and area fractions of each component. It is shown that, as the radius\nof the particle is increased, the effect of the particles on the\nisotropic-nematic transition is less pronounced, and that for large radius the\nmiscibility increases as the particle radius increases.",
        "positive": "The Eshelby problem in amorphous solids: The ``Eshelby problem\" refers to the response of a 2-dimensional elastic\nsheet to cutting away a circle, deforming it into an ellipse, and pushing it\nback. The resulting response is dominated by the so-called ``Eshelby Kernel\"\nwhich was derived for purely elastic (infinite) material, but has been employed\nextensively to model the redistribution of stress after plastic events in\namorphous solids with finite boundaries. Here we discuss and solve the Eshelby\nproblem directly for amorphous solids, taking into account possible screening\neffects and realistic boundary conditions. We find major modifications compared\nto the classical Eshelby solution. These modification are needed for modeling\ncorrectly the spatial responses to plastic events in amorphous solids."
    },
    {
        "anchor": "Thiol-amine co-solvents aided direct synthesis of ZnTe thin films by\n  spin coating for low cost optoelectronic applications: Zinc telluride (ZnTe) thin films have special semiconducting characteristics\nthat make them very promising for a broad range of optoelectronic applications.\nIn this work, a novel approach for synthesizing ZnTe thin films by spin coating\ntechnique is followed using a unique solution process with ZnTe directly\ndissolving in thiol-amine co-solvents. Thin films are synthesized on glass\nsubstrates and air annealed at 250-350 {\\deg}C. The polycrystalline phase of\nZnTe is revealed through the X-ray diffraction (XRD) study. The scanning\nelectron microscopy (SEM) is used to observe the evolution of surface\nsmoothness with annealing temperature. Moreover, elemental compositions of ZnTe\nthin film have been determined by energy dispersive spectroscopy (EDS) study.\nFTIR spectroscopy reveals that ZnTe has been successfully synthesized as\nconfirmed by the characteristic peaks in the spectrum of 750-1000 cm-1. Optical\nproperties of the ZnTe thin films have been investigated using UV-vis\nspectroscopy. The transmittance of the films increases with annealing\ntemperature. Furthermore, the optical bandgaps of the films of 2.92, 2.84, and\n2.5 eV have been found at 250, 300, and 350 {\\deg}C annealing temperatures,\nrespectively. These results suggest that controlling the annealing environment\nserves as a valuable strategy for tailoring the ZnTe film properties to meet\nspecific application requirements. These results reveal that spin coated ZnTe\nthin films are attractive ones for various applications in optoelectronic\ndevices such as solar cells and photodetectors.",
        "positive": "Crossover from First to Second-Order Transition in Frustrated Ising\n  Antiferromagnetic Films: In the bulk state, the Ising FCC antiferromagnet is fully frustrated and is\nknown to have a very strong first-order transition. In this paper, we study the\nnature of this phase transition in the case of a thin film, as a function of\nthe film thickness. Using Monte Carlo (MC) simulations, we show that the\ntransition remains first order down to a thickness of four FCC cells. It\nbecomes clearly second order at a thickness of two FCC cells, i.e. four atomic\nlayers. It is also interesting to note that the presence of the surface reduces\nthe ground state (GS) degeneracy found in the bulk. For the two-cell thickness,\nthe surface magnetization is larger than the interior one. It undergoes a\nsecond-order phase transition at a temperature $T_C$ while interior spins\nbecome disordered at a lower temperature $T_D$. This loss of order is\ncharacterized by a peak of the interior spins susceptibility and a peak of the\nspecific heat which do not depend on the lattice size suggesting that either it\nis not a real transition or it is a Kosterlitz-Thouless nature. The surface\ntransition, on the other hand, is shown to be of second order with critical\nexponents deviated from those of pure 2D Ising universality class. We also show\nresults obtained from the Green's function method. Discussion is given."
    },
    {
        "anchor": "Dielectric constant of gray Tin: A first-principles study: $\\alpha$-Sn (gray tin) is a group-IV, zero-gap semiconductor with potential\nuse in infrared detectors, necessitating a clear understanding of its\ndielectric properties. We report the first-principles calculations of the band\nstructure and dielectric function of $\\alpha$-Sn using density functional\ntheory, emphasizing the effects of strain, spin-orbit interaction, and\npseudo-potentials on the electronic and optical properties of $\\alpha$-Sn in\nthe infrared region (photon energy $<$ 1eV). In $\\alpha$-Sn, spin-orbit\ncoupling greatly influences the electronic band structure that leads to unusual\noptical behavior. We explain an apparently anomalous absorption at $\\sim$ 0.41\neV caused by interbank transitions within the valence band. Infrared\nspectroscopic ellipsometry on several $\\alpha$-Sn films grown by molecular beam\nepitaxy validate our band-structure calculations. Our computational methods and\nresults are discussed in detail.",
        "positive": "Trends in Bandgap of Epitaxial $\\textit{A}$$_2$$\\textit{B}$$_2$O$_7$\n  ($\\textit{A}$ = Sn, Pb; $\\textit{B}$ = Nb, Ta) Films Fabricated by Pulsed\n  Laser Deposition: Pyrochlore oxides $A_2B_2$O$_7$ have been a fruitful playground for condensed\nmatter physics because of the unique geometry in the crystal structure.\nEspecially focusing on the $A$-site tetrahedral sub-lattice, in particular,\npyrochlore oxides $A_2B_2$O$_7$ ($A$ = Sn, Pb and $B$ = Nb, Ta), recent\ntheoretical studies predict the emergence of the \"quasi-flat band\" structure as\na result of the strong hybridization between filled $A$-n$s$ and O-2$p$\norbitals. In this work, we have established the growth conditions of\nSn$_2$Nb$_2$O$_7$, Sn$_2$Ta$_2$O$_7$, Pb$_2$Nb$_2$O$_7$, and Pb$_2$Ta$_2$O$_7$\nfilms by pulsed laser deposition on Y-stabilized ZrO$_2$ (111) substrates to\nelucidate their optical properties. Absorption-edge energies, both for direct\nand indirect bandgaps, increase in the order of Sn$_2$Nb$_2$O$_7$,\nSn$_2$Ta$_2$O$_7$, Pb$_2$Nb$_2$O$_7$, and Pb$_2$Ta$_2$O$_7$. This tendency can\nbe well explained by considering the energy level of the constituent elements.\nA comparison of the difference between direct and indirect bandgaps reveals\nthat Pb$_2B_2$O$_7$ tends to have a less dispersive valence band than\nSn$_2B_2$O$_7$. Our findings are consistent with the theoretical predictions\nand are suggestive of the common existence of the hybridized states in this\nclass of compounds."
    },
    {
        "anchor": "Electronic states and self-doping at a 45^o YBa2Cu3O7 grain boundary: The charge redistribution at grain boundaries determines the applicability of\nhigh-Tc superconductors in electronic devices, because the transport across the\ngrains can be hindered considerably. We investigate the local charge transfer\nand the modification of the electronic states in the vicinity of the\ngrain-grain interface by first principles calculations for a (normal-state)\n45^o tilted [001] grain boundary in YBa2Cu3O7. Our results explain the\nsuppressed interface transport and the influence of grain boundary doping in a\nquantitative manner, in accordance with the experimental situation. The charge\nredistribution is found to be strongly inhomogeneous, which has a substantial\neffect on transport properties since it gives rise to a self-doping of 0.10\n(+/- 0.02) holes per Cu atom.",
        "positive": "Structural and electronic properties of Fe(AlxGa1-x)3 system: FeGa3 is a well known d-p hybridization induced intermetallic bandgap\nsemiconductor. In this work, we present the experimental and theoretical\nresults on the effect of Al substitution in FeGa3, obtained by x-ray\ndiffraction (XRD), temperature dependent resistance measurement, room\ntemperature Mossbauer measurements and density functional theory based\nelectronic structure calculations. It is observed that upto x = 0.178 in\nFe(AlxGa1-x)3, which is the maximum range studied in this work, Al substitution\nreduces the lattice parameters 'a' and 'c' preserving the parent tetragonal\nP42/mnm crystal structure of FeGa3. The bandgap of Fe(AlxGa1-x)3 for x = 0.178\nis reduced by ~ 24% as compared to FeGa3. Rietveld refinement of the XRD data\nshows that the Al atoms replace Ga atoms located at the 8j sites in FeGa3. A\ncomparison of the trends of the lattice parameters and energy bandgap observed\nin the calculations and the experiments also confirms that Al primarily\nreplaces the Ga atoms in the 8j site."
    },
    {
        "anchor": "How to verify the precision of density-functional-theory implementations\n  via reproducible and universal workflows: In the past decades many density-functional theory methods and codes adopting\nperiodic boundary conditions have been developed and are now extensively used\nin condensed matter physics and materials science research. Only in 2016,\nhowever, their precision (i.e., to which extent properties computed with\ndifferent codes agree among each other) was systematically assessed on\nelemental crystals: a first crucial step to evaluate the reliability of such\ncomputations. We discuss here general recommendations for verification studies\naiming at further testing precision and transferability of\ndensity-functional-theory computational approaches and codes. We illustrate\nsuch recommendations using a greatly expanded protocol covering the whole\nperiodic table from Z=1 to 96 and characterizing 10 prototypical cubic\ncompounds for each element: 4 unaries and 6 oxides, spanning a wide range of\ncoordination numbers and oxidation states. The primary outcome is a reference\ndataset of 960 equations of state cross-checked between two all-electron codes,\nthen used to verify and improve nine pseudopotential-based approaches. Such\neffort is facilitated by deploying AiiDA common workflows that perform\nautomatic input parameter selection, provide identical input/output interfaces\nacross codes, and ensure full reproducibility. Finally, we discuss the extent\nto which the current results for total energies can be reused for different\ngoals (e.g., obtaining formation energies).",
        "positive": "First-principles study of exchange interactions and Curie temperatures\n  of half-metallic ferrimagnetic full Heusler alloys Mn2VZ (Z=Al, Ge): We report the parameter-free, density functional theory calculations of\ninteratomic exchange interactions and Curie temperatures of half-metallic\nferrimagnetic full Heusler alloys Mn2VZ (Z=Al, Ge). To calculate the\ninteratomic exchange interactions we employ the frozen-magnon approach. The\nCurie temperatures are calculated within the mean-field approximation to the\nclassical Heisenberg Hamiltonian by solving a matrix equation for a\nmulti-sublattice system. Our calculations show that, although a large magnetic\nmoment is carried by Mn atoms, competing ferromagnetic (inter sublattice) and\nantiferromagnetic (intra sublattice) Mn-Mn interactions in Mn2VAl almost cancel\neach other in the mean-field experienced by the Mn atoms. In Mn2VGe the leading\nMn-Mn exchange interaction is antiferromagnetic. In both compounds the\nferromagnetism of the Mn subsystem is favored by strong antiferromagnetic Mn-V\ninteractions. The obtained value of the Curie temperature of Mn2VAl is in good\nagrement with experiment. For Mn2VGe there is no experimental information\navailable and our calculation is a prediction."
    },
    {
        "anchor": "Current-driven vortex oscillations in metallic nanocontacts: We present experimental evidence of sub-GHz spin-transfer oscillations in\nmetallic nano-contacts that are due to the translational motion of a magnetic\nvortex. The vortex is shown to execute large-amplitude orbital motion outside\nthe contact region. Good agreement with analytical theory and micromagnetics\nsimulations is found.",
        "positive": "Liquid-like thermal conduction in a crystalline solid: A solid conducts heat through both transverse and longitudinal acoustic\nphonons, but a liquid employs only longitudinal vibrations. Here, we report\nthat the crystalline solid AgCrSe2 has liquid-like thermal conduction. In this\ncompound, Ag atoms exhibit a dynamic duality that they are exclusively involved\nin intense low-lying transverse acoustic phonons while they also undergo local\nfluctuations inherent in an order-to-disorder transition occurring at 450 K. As\na consequence of this extreme disorder-phonon coupling, transverse acoustic\nphonons become damped as approaching the transition temperature, above which\nthey are not defined anymore because their lifetime is shorter than the\nrelaxation time of local fluctuations. Nevertheless, the damped longitudinal\nacoustic phonon survives for thermal transport. This microscopic insight might\nreshape the fundamental idea on thermal transport properties of matter and\nfacilitates the optimization of thermoelectrics."
    },
    {
        "anchor": "Local polarization and valence distribution in LaNiO3/LaMnO3\n  heterostructures: The inside of the electrical double layer at perovskite oxide\nheterointerfaces is examined. Here, we report the local polarization and\nvalence distribution in LaNiO$_3$/LaMnO$_3$ and LaMnO$_3$/LaNiO$_3$ bilayers on\na SrTiO$_3$ (001) substrate. Simultaneous measurements of two aspects of the\nstructure are realized by using Bayesian inference based on resonant- and\nnonresonant-surface X-ray diffraction data. The results show that the average\nMn valences are Mn$^{3.12+}$ and Mn$^{3.19+}$ for the two samples. The\nintensity of their local electric field is $\\sim$1~GV/m and the direction of\nthe field points from LaMnO$_3$ to LaNiO$_3$.",
        "positive": "The solid state phase transformation of potassium sulfate: Potassium sulfate single crystals that are grown from aqueous solutions lose\nupon the first heating up to 1% of mass that is assumed to be water. This mass\nloss occurs in the vicinity of the PT from orthorhombic to hexagonal K2SO4.\nOnly in the first heating run of K2SO4 that has not yet released water,\npretransitional thermal effects can be observed in the DTA curve. If K2SO4\ncrystals are grown from solutions containing 4 wt.% Cd, Cu, or Fe, only Cu or\nFe can be incorporated significantly with concentrations of several 0.1%. The\nphase transformation temperature measured for such solid solutions depends on\nthe heating rate. For pure K2SO4, the phase transformation temperature is\nindependent on heating rate 581.3 deg. C and the enthalpy of transformation is\n(5.8+/-0.2) kJ/mol."
    },
    {
        "anchor": "Theoretical study of the structural stability, electronic and magnetic\n  properties of XVSb (X $=$ Fe, Ni, and Co) half-Heusler compounds: The structural, electronic and magnetic properties of half-Heusler compounds\nXVSb (X $=$ Fe, Co and Ni) are investigated by using the density functional\ntheory with generalized gradient approximation (GGA), and Tran-Blaha modified\nBecke-Johnson (TB-mBJ) exchange potential approximation. It is found that the\nhalf-metallic gaps are generally reasonably widened by mBJ as compared to the\nGGA approximation. The magnetic proprieties of XVSb (X $=$ Fe, Co and Ni) are\nwell defined within mBJ with an exact integer value of magnetic moment. The\nband gaps given by TB-mBJ are in good agreement with the available theoretical\ndata. The FeVSb exhibits a semiconductor nature. The CoVSb and NiVSb present\nhalf-metallic behaviour with total magnetic moment of $1\\mu_\\text{B}$ and\n$2\\mu_\\text{B}$ in good agreement with Slater-Pauling rule. These alloys seem\nto be a potential candidate of spintronic devices.",
        "positive": "Fabrication of highly dense isotropic Nd-Fe-B bonded magnets via\n  extrusion-based additive manufacturing: Isotropic bonded magnets with a high loading fraction of 70 vol.% Nd-Fe-B are\nfabricated via an extrusion-based additive manufacturing, or 3D printing system\nthat enables rapid production of large parts for the first time. The density of\nthe printed magnet is 5.15 g/cm3. The room temperature magnetic properties are:\nintrinsic coercivity Hci = 8.9 kOe (708.2 kA/m), remanence Br = 5.8 kG (0.58\nTesla), and energy product (BH)max = 7.3 MGOe (58.1 kJ/m3). The as-printed\nmagnets are then coated with two types of polymers, both of which improve the\nthermal stability at 127 {\\deg}C as revealed by flux aging loss measurements.\nTensile tests performed at 25 {\\deg}C and 100 {\\deg}C show that the ultimate\ntensile stress (UTS) increases with increasing loading fraction of the magnet\npowder, and decreases with increasing temperature. AC magnetic susceptibility\nand resistivity measurements show that the 3D printed Nd-Fe-B bonded magnets\nexhibit extremely low eddy current loss and high resistivity. Finally, we show\nthat through back electromotive force measurements that motors installed with\n3D printed Nd-Fe-B magnets exhibit similar performance as compared to those\ninstalled with sintered ferrites."
    },
    {
        "anchor": "Unsupervised topological learning approach of crystal nucleation in pure\n  Tantalum: Nucleation phenomena commonly observed in our every day life are of\nfundamental, technological and societal importance in many areas, but some of\ntheir most intimate mechanisms remain however to be unraveled. Crystal\nnucleation, the early stages where the liquid-to-solid transition occurs upon\nundercooling, initiates at the atomic level on nanometer length and\nsub-picoseconds time scales and involves complex multidimensional mechanisms\nwith local symmetry breaking that can hardly be observed experimentally in the\nvery details. To reveal their structural features in simulations without a\npriori, an unsupervised learning approach founded on topological descriptors\nloaned from persistent homology concepts is proposed. Applied here to a\nmonatomic metal, namely Tantalum (Ta), it shows that both translational and\norientational ordering always come into play simultaneously when homogeneous\nnucleation starts in regions with low five-fold symmetry.",
        "positive": "Orthotropic Piezoelectricity in 2D Nanocellulose: The control of electromechanical responses within bonding regions is\nessential to face frontier challenges in nanotechnologies, such as molecular\nelectronics and biotechnology. Here, we present I\\b{eta}-nanocellulose as a\npotentially new orthotropic 2D piezoelectric crystal. The predicted in-layer\npiezoelectricity is originated on a sui-generis hydrogen bonds pattern. Upon\nthis fact and by using a combination of ab-initio and ad-hoc models, we\nintroduce a description of electrical profiles along chemical bonds. Such\ndevelopments lead to obtain a rationale for modelling the extended\npiezoelectric effect originated within bond scales. The order of magnitude\nestimated for the 2D I\\b{eta}-nanocellulose piezoelectric response, ~pm V-1,\nranks this material at the level of currently used piezoelectric energy\ngenerators and new artificial 2D designs. Such finding would be crucial for\ndeveloping alternative materials to drive emerging nanotechnologies."
    },
    {
        "anchor": "Polaron Recombination in Pristine and Annealed Bulk Heterojunction Solar\n  Cells: We determined the dominant polaron recombination loss mechanism in pristine\nand annealed polythiophene:fullerene blend solar cells by applying the\nphoto-induced charge extraction by linearly increasing voltage (photo-CELIV)\nmethod in dependence on temperature. In pristine samples, we find a strongly\ntemperature dependent bimolecular polaron recombination rate, which is reduced\nas compared to the Langevin theory. For the annealed sample, we observe a\npolaron decay rate which follows a third order of carrier concentration almost\ntemperature independently.",
        "positive": "Defect states and their electric field-enhanced electron thermal\n  emission in heavily Zr-doped beta-Ga2O3 crystals: Performing deep level transient spectroscopy (DLTS) on Schottky diodes, we\ninvestigated defect levels below the conduction band minima (Ec) in Czochralski\n(CZ) grown unintentionally-doped (UID) and vertical gradient freeze (VGF)-grown\nZr-doped beta-Ga2O3 crystals. In UID crystals with an electron concentration of\n10^17 cm-3, we observe levels at 0.18 eV and 0.46 eV in addition to the\npreviously reported 0.86 (E2) and 1.03 eV (E3) levels. For 10^18 cm-3 Zr-doped\nGa2O3, signatures at 0.30 eV (E15) and 0.71 eV (E16) are present. For the\nhighest Zr doping of 5*10^18 cm-3, we observe only one signature at 0.59 eV.\nElectric field-enhanced emission rates are demonstrated via increasing the\nreverse bias during measurement. The 0.86 eV signature in the UID sample\ndisplays phonon-assisted tunneling enhanced thermal emission and is consistent\nwith the widely reported E2 (FeGa) defect. The 0.71 eV (E16) signature in the\nlower-Zr-doped crystal also exhibits phonon-assisted tunneling emission\nenhancement. Taking into account that the high doping in the Zr-doped diodes\nalso increases the electric field, we propose that the 0.59 eV signature in the\nhighest Zr-doped sample likely corresponds to the 0.71 eV signature in\nlower-doped samples. Our analysis highlights the importance of testing for and\nreporting on field-enhanced emission especially the electric field present\nduring DLTS and other characterization experiments on beta-Ga2O3 along with the\nstandard emission energy, cross-section, and lambda-corrected trap density.\nThis is important because of the intended use of beta-Ga2O3 in high-field\ndevices and the many orders of magnitude of possible doping."
    },
    {
        "anchor": "Spatially and time-resolved imaging of transport of indirect excitons in\n  high magnetic fields: We present the direct measurements of magnetoexciton transport. Excitons give\nthe opportunity to realize the high magnetic field regime for composite bosons\nwith magnetic fields of a few Tesla. Long lifetimes of indirect excitons allow\nthe study kinetics of magnetoexciton transport with time-resolved optical\nimaging of exciton photoluminescence. We performed spatially, spectrally, and\ntime-resolved optical imaging of transport of indirect excitons in high\nmagnetic fields. We observed that increasing magnetic field slows down\nmagnetoexciton transport. The time-resolved measurements of the magnetoexciton\ntransport distance allowed for an experimental estimation of the magnetoexciton\ndiffusion coefficient. An enhancement of the exciton photoluminescence energy\nat the laser excitation spot was found to anti-correlate with the exciton\ntransport distance. A theoretical model of indirect magnetoexciton transport is\npresented and is in agreement with the experimental data.",
        "positive": "Local magnetism and structural properties of Heusler Ni$_2$MnGa alloys: We present a detailed experimental study of bulk and powder samples of the\nHeusler shape memory alloy Ni$_2$MnGa, including zero-field static and dynamic\n$^{55}$Mn NMR experiments, X-ray powder diffraction and magnetization\nexperiments. The NMR spectra give direct access to the sequence of structural\nphase transitions in this compound, from the high-T austenitic phase down to\nthe low-T martensitic phase. In addition, a detailed investigation of the\nso-called rf-enhancement factor provides local information for the magnetic\nstiffness and restoring fields for each separate coordination, structural,\ncrystallographic environment, thus differentiating signals coming from\naustenitic and martensitic components. The temperature evolution of the NMR\nspectra and the rf-enhancement factors shows strong dependence on sample\npreparation. In particular, we find that sample powderization gives rise to a\nsignificant portion of martensitic traces inside the high-T austenitic region,\nand that these traces can be subsequently removed by annealing."
    },
    {
        "anchor": "Spin-accumulation capacitance and its application to magnetoimpedance: It has been known that spin-dependent capacitances usually coexist with\ngeometric capacitances in a magnetic multilayer. However, the charge and energy\nstorage of the capacitance due to spin accumulation has not been fully\nunderstood. Here, we resolve this problem starting from the charge storage in\nthe spin degree of freedom: spin accumulation manifests itself as an excess of\nelectrons in one spin channel and an equal deficiency in the other under the\nquasi-neutrality condition. This enables us to model the two spin channels as\nthe two plates of a capacitor. Taking a ferromagnet/nonmagnet junction as an\nexample and using a method similar to that for treating quantum capacitance, we\nfind that a spin-accumulation (SA) capacitance can be introduced for each layer\nto measure its ability to store spins. A spatial charge storage is not\nessential for the SA capacitor and the energy stored in it is the splitting\nenergy of the spin-dependent chemical potentials instead of the electrostatic\nenergy. The SA capacitance is essentially a quantum capacitance due to spin\naccumulation on the scale of the spin-diffusion length. The SA capacitances can\nbe used to reinterpret the imaginary part of the low-frequency\nmagnetoimpedance.",
        "positive": "Phase-field simulations of solidification in binary and ternary systems\n  using a finite element method: We present adaptive finite element simulations of dendritic and eutectic\nsolidification in binary and ternary alloys. The computations are based on a\nrecently formulated phase-field model that is especially appropriate for\nmodelling non-isothermal solidification in multicomponent multiphase systems.\nIn this approach, a set of governing equations for the phase-field variables,\nfor the concentrations of the alloy components and for the temperature has to\nbe solved numerically, ensuring local entropy production and the conservation\nof mass and inner energy. To efficiently perform numerical simulations, we\ndeveloped a numerical scheme to solve the governing equations using a finite\nelement method on an adaptive non-uniform mesh with highest resolution in the\nregions of the phase boundaries. Simulation results of the solidification in\nternary Ni$_{60}$Cu$_{40-x}$Cr$_{x}$ alloys are presented investigating the\ninfluence of the alloy composition on the growth morphology and on the growth\nvelocity. A morphology diagram is obtained that shows a transition from a\ndendritic to a globular structure with increasing Cr concentrations.\nFurthermore, we comment on 2D and 3D simulations of binary eutectic phase\ntransformations. Regular oscillatory growth structures are observed combined\nwith a topological change of the matrix phase in 3D. An outlook for the\napplication of our methods to describe AlCu eutectics is given."
    },
    {
        "anchor": "Phase Transitions and Antiferroelectrivity in BiFeO3 from Atomic Level\n  Simulations: The structural and polar properties of BiFeO3 at finite temperature are\ninvestigated using an atomistic shell model fitted to first-principles\ncalculations. Molecular Dynamics simulations show a direct transition from the\nlow-temperature R3c ferroelectric phase to the Pbnm orthorhombic phase without\nevidence of any intermediate bridging phase between them. The high-temperature\nphase is characterized by the presence of two sublattices with opposite\npolarizations, and it displays the characteristic double-hysteresis loop under\nthe action of an external electric field. The microscopic analysis reveals that\nthe change in the polar direction and the large lattice strains observed during\nthe antiferroelectric-ferroelectric phase transition originate from the\ninterplay between polarization, oxygen octahedron rotations and strain. As a\nresult, the induced ferroelectric phase recovers the symmetry of the low\ntemperature R3c phase.",
        "positive": "The influence of transition metal solutes on dislocation core structure\n  and values of Peierls stress and barrier in tungsten: Several transition metals were examined to evaluate their potential for\nimproving the ductility of tungsten. The dislocation core structure and Peierls\nstress and barrier of $1/2<111>$ screw dislocations in binary\ntungsten-transition metal alloys (W$_{1-x}$TM$_{x}$) were investigated using\nfirst principles electronic structure calculations. The periodic quadrupole\napproach was applied to model the structure of $1/2<111>$ dislocation. Alloying\nwith transition metals was modeled using the virtual crystal approximation and\nthe applicability of this approach was assessed by calculating the equilibrium\nlattice parameter and elastic constants of the tungsten alloys. Reasonable\nagreement was obtained with experimental data and with results obtained from\nthe conventional supercell approach. Increasing the concentration of a\ntransition metal from the VIIIA group, i.e. the elements in columns headed by\nFe, Co and Ni, leads to reduction of the $C^\\prime$ elastic constant and\nincrease of elastic anisotropy A=$C_{44}/C^\\prime$. Alloying W with a group\nVIIIA transition metal changes the structure of the dislocation core from\nsymmetric to asymmetric, similar to results obtained for W$_{1-x}$Re$_{x}$\nalloys in the earlier work of Romaner {\\it et al} (Phys. Rev. Lett. 104, 195503\n(2010))\\comments{\\cite{WRECORE}}. In addition to a change in the core symmetry,\nthe values of the Peierls stress and barrier are reduced. The latter effect\ncould lead to increased ductility in a tungsten-based\nalloy\\comments{\\cite{WRECORE}}. Our results demonstrate that alloying with any\nof the transition metals from the VIIIA group should have similar effect as\nalloying with Re."
    },
    {
        "anchor": "Monoclinic symmetry at the nanoscale in lead-free ferroelectric\n  BaZr$_{x}$Ti$_{1-x}$O$_{3}$ ceramics: Local structural symmetries play a key role in the functionalities of\nferroelectric materials and are often found different from average symmetry.\nHere, we study the real space nanoscale structure in Pb-free\nBaZr$_{x}$Ti$_{1-x}$O$_{3}$ (x $\\leq$ 0.10) by pair distribution function\nmeasurements, complemented by transmission electron microscopy and x-ray\ndiffraction. Our observations show existence of the rhombohedrally distorted\nunit cells; however, at intermediate length scales, at least up to 5 nm, there\nexist nano-scale correlated regions of monoclinic symmetry. This is\ncomplemented by the observation of curved frustrated nanodomains. Further, the\naverage structure is found to have coexisting monoclinic and rhombohedral\nsymmetries. Our observation of a two-phase ferroelectric state is in contrast\nto interferroelectric instabilities of conventional polymorphic phase\nboundaries reported for doped BaTiO$_{3}$.",
        "positive": "Inverse Design of Ultralow Lattice Thermal Conductivity Materials Via\n  Lone Pair Cation Coordination Environment: The presence of lone pair (LP) electrons is strongly associated with the\ndisruption of lattice heat transport, which is a critical component of\nstrategies to achieve efficient thermoelectric energy conversion. By exploiting\nan empirical relationship between lattice thermal conductivity $\\kappa_L$ and\nthe bond angles of pnictogen group LP cation coordination environments, we\ndevelop an inverse design strategy based on a materials database screening to\nidentify chalcogenide materials with ultralow $\\kappa_L$ for thermoelectrics.\nScreening the $\\sim$ 635,000 real and hypothetical inorganic crystals of the\nOpen Quantum Materials Database based on the constituent elements, nominal\nelectron counting, LP cation coordination environment, and synthesizability, we\nidentify 189 compounds expected to exhibit ultralow $\\kappa_L$. As a\nvalidation, we explicitly compute the lattice dynamical properties of two of\nthe compounds (Cu$_2$AgBiPbS$_4$ and MnTl$_2$As$_2$S$_5$) using\nfirst-principles calculations and successfully find both achieve ultralow\n$\\kappa_L$ values at room temperature of $\\sim$ 0.3--0.4 W/(m$\\cdot$K)\ncorresponding to the amorphous limit. Our data-driven approach provides\npromising candidates for thermoelectric materials and opens new avenues for the\ndesign of phononic properties of materials."
    },
    {
        "anchor": "Strain-tunable band gap of a monolayer graphene analogue of ZnS\n  monolayer: Using first-principles full-potential density functional calculations, we\npredict that mechanically tunable band-gap is realizable in ZnS monolayer in\ngraphene-like honeycomb structure by application of in-plane homogeneous\nbiaxial strain. A transition point from direct-to-indirect gap-phase is\npredicted to exist for biaxial tensile strain lying in the interval (2.645%,\n3.171%). In the two gap-phases, the band gap decreases with increasing strain\nand varies linearly with strain.",
        "positive": "The Stability of an Expanding Circular Cavity and the Failure of\n  Amorphous Solids: Recently, the existence and properties of unbounded cavity modes, resulting\nin extensive plastic deformation failure of two-dimensional sheets of amorphous\nmedia, were discussed in the context of the athermal Shear-Transformation-Zones\n(STZ) theory. These modes pertain to perfect circular symmetry of the cavity\nand the stress conditions. In this paper we study the shape stability of the\nexpanding circular cavity against perturbations, in both the unbounded and the\nbounded growth regimes (for the latter the unperturbed theory predicts no\ncatastrophic failure). Since the unperturbed reference state is time dependent,\nthe linear stability theory cannot be cast into standard time-independent\neigenvalue analysis. The main results of our study are: (i) sufficiently small\nperturbations are stable, (ii) larger perturbations within the formal linear\ndecomposition may lead to an instability; this dependence on the magnitude of\nthe perturbations in the linear analysis is a result of the non-stationarity of\nthe growth, (iii) the stability of the circular cavity is particularly\nsensitive to perturbations in the effective disorder temperature; in this\ncontext we highlight the role of the rate sensitivity of the limiting value of\nthis effective temperature. Finally we point to the importance of the form of\nthe stress-dependence of the rate of STZ transitions. The present analysis\nindicates the importance of nonlinear effects that were not taken into account\nyet. Even more importantly, the analysis suggests that details of the\nconstitutive relations appearing in the theory can be constrained by the modes\nof macroscopic failure in these amorphous systems."
    },
    {
        "anchor": "Highly ordered LIPSS on Au thin film for plasmonic sensing fabricated by\n  double femtosecond pulses: We report on the single-step fabrication of homogeneous and highly ordered\nLaser Induced Periodic Surface Structures (LIPSS) over large areas on Au\nnanolayers, that can be used for plasmonic sensing. A comprehensive study on\nLIPSS formation on 32 nm Au film upon double, 170 fs pulse irradiation,\nunveiled the key importance of interpulse delay as the determining factor\nbehind the homogeneity of laser induced structures and confirmed that highly\nordered, functional LIPSS occur solely upon double pulse irradiation. In\nparticular, the impact of pulse overlap, fluence and interpulse delay reveals\nthat homogeneous LIPSS formation is optimized within a specific interpulse\ndelay range. At the same time, examination of nanoscale features of the\nstructures points out a significant differentiation of the LIPSS formation\ncharacteristics between single and double pulse irradiation. Theoretical\ninvestigation complements experimental results providing insights on the\nstructure formation mechanism. Ellipsometric measurements validate that such\nstructures exhibit characteristic plasmon resonances that can be exploited for\nsensing applications. The presented data demonstrate a novel functionality of\nLIPSS, while providing strong evidence of the capabilities of femtosecond\ndouble pulse irradiation as a valuable and low-cost tool for the precise\nfabrication of highly ordered structures.",
        "positive": "Development of an Interatomic Potential for the Simulation of Defects,\n  Plasticity and Phase Transformations in Titanium: New interatomic potentials describing defects, plasticity and high\ntemperature phase transitions for Ti are presented. Fitting the martensitic\nhcp-bcc phase transformation temperature requires an efficient and accurate\nmethod to determine it. We apply a molecular dynamics (MD) method based on\ndetermination of the melting temperature of competing solid phases, and\nGibbs-Helmholtz integration, and a lattice-switch Monte Carlo method (LSMC):\nthese agree on the hcp-bcc transformation temperatures to within 2 K. We were\nable to develop embedded atom potentials which give a good fit to either low or\nhigh temperature data, but not both. The first developed potential (Ti1)\nreproduces the hcp-bcc transformation and melting temperatures and is suitable\nfor the simulation of phase transitions and bcc Ti. Two other potentials (Ti2\nand Ti3) correctly describe defect properties, and can be used to simulate\nplasticity or radiation damage in hcp Ti. The fact that a single EAM potential\ncannot describe both low and high temperature phases may be attributed to\nneglect of electronic degrees of freedom, notably bcc has a much higher\nelectronic entropy. A temperature-dependent potential obtained from the\ncombination of potentials Ti1 and Ti2 may be used to simulate Ti properties at\nany temperature."
    },
    {
        "anchor": "Direct observation of band bending in topological insulator Bi2Se3: The surface band bending tunes considerably the surface band structures and\ntransport properties in topological insulators. We present a direct measurement\nof the band bending on the Bi2Se3 by using the bulk sensitive angular-resolved\nhard x-ray photospectroscopy (HAXPES). We tracked the depth dependence of the\nenergy shift of Bi and Se core states. We estimate that the band bending\nextends up to about 20 nm into the bulk with an amplitude of 0.23--0.26 eV,\nconsistent with profiles previously deduced from the binding energies of\nsurface states in this material.",
        "positive": "Stabilities and novel electronic structures of three carbon nitride\n  bilayers: Three new novel phases of carbon nitride (CN) bilayer, which are named as\n\\alpha-C$_{2}$N$_{2}$, \\beta-C$_{2}$N$_{2}$ and \\gamma-C$_{4}$N$_{4}$,\nrespectively, have been predicted in this paper. All of them are consisted of\ntwo CN sheets connected by C-C covalent bonds. The phonon dispersions reveal\nthat all these phases are dynamically stable, since no imaginary frequency is\nfound for them. Transition path way between \\alpha-C$_{2}$N$_{2}$ and\n\\beta-C$_{2}$N$_{2}$ is investigated, which involves bond-breaking and\nbond-reforming between C and N. This conversion is difficult, since the\nactivation energy barrier is found to be 1.90 eV per unit cell, high enough to\nprevent the transformation at room temperature. Electronic structures\ncalculations show that they are all semiconductors with indirect band gap of\n3.76 / 5.22 eV, 4.23 / 5.75 eV and 2.06 / 3.53 eV by PBE / HSE calculation,\nrespectively. The \\beta-C$_{2}$N$_{2}$ has the widest band gap among the three\nphases. From our results, the three new two-dimensional materials have\npotential applications in the electronics, semiconductors, optics and\nspintronics."
    },
    {
        "anchor": "Multiscale simulations of topological transformations in magnetic\n  Skyrmions: Magnetic Skyrmions belong to the most interesting spin structures for the\ndevelopment of future information technology as they have been predicted to be\ntopologically protected. To quantify their stability, we use an innovative\nmultiscale approach to simulating spin dynamics based on the\nLandau-Lifshitz-Gilbert equation. The multiscale approach overcomes the\nmicromagnetic limitations that have hindered realistic studies using\nconventional techniques. We first demonstrate how the stability of a Skyrmion\nis influenced by the refinement of the computational mesh and reveal that\nconventionally employed traditional micromagnetic simulations are inadequate\nfor this task. Furthermore, we determine the stability quantitatively using our\nmultiscale approach. As a key operation for devices, the process of\nannihilating a Skyrmion by exciting it with a spin polarized current pulse is\nanalyzed, showing that Skyrmions can be reliably deleted by designing the pulse\nshape.",
        "positive": "Theoretical study of the (3x2) reconstruction of beta-SiC(001): By means of ab initio molecular dynamics and band structure calculations, as\nwell as using calculated STM images, we have singled out one structural model\nfor the (3x2) reconstruction of the Si-terminated (001) surface of cubic SiC,\namongst several proposed in the literature. This is an alternate dimer-row\nmodel, with an excess Si coverage of 1/3, yielding STM images in good accord\nwith recent measurements [F.Semond et al. Phys. Rev. Lett. 77, 2013 (1996)]."
    },
    {
        "anchor": "Caracterizaci\u00f3n de austenita expandida generada por cementaci\u00f3n\n  i\u00f3nica de aceros inoxidables. Estudio de la estabilidad frente a la\n  irradiaci\u00f3n con haces de iones ligeros energ\u00e9ticos: This thesis was focused on the surface modification with plasma discharge.\nAustenitic AISI 316L stainless steel sample was carburised under different\nexperimental conditions and mechanical properties have been studied (thickness,\nlattice parameter, elemental composition, hardness, wear resistance and\ncorrosion resistance). After that, steel substrates have been nitrided or\ncarburised in order to analyse their stability under ion bombardment using a\nplasma focus device. Helium and deuterium were the gases used in 0, 1, 5, and\n10 discharges. Optical and X-ray characterisations were used. Finally, using\nmagnetron sputtering nitrided/carburised samples were coated with an AlN thin\nfilm in order to study their stability under long treatments at high\ntemperatures.",
        "positive": "Ultrasonic control of terahertz radiation via lattice anharmonicity in\n  LiNbO3: We propose a novel tunable terahertz (THz) filter using the resonant\nacousto-optic (RAO) effect. We present a design based on a transverse optical\n(TO) phonon mediated interaction between a coherent acoustic wave and the THz\nfield in LiNbO3. We predict a continuously tunable range of the filter up to 4\nTHz via the variation of the acoustic frequency between 0.1 and 1 GHz. The RAO\neffect in this case is due to cubic and quartic anharmonicities between TO\nphonons and the acoustic field. The effect of the interference between the\nanharmonicities is also discussed."
    },
    {
        "anchor": "Novel Electronic Structure of Nitrogen-Doped Lutetium Hydrides: First-principles density functional theory (DFT) calculations of Lu-H-N\ncompounds reveal low-energy configurations of Fm$\\overline{3}$m\nLu$_{8}$H$_{23-x}$N structures that exhibit novel electronic properties such as\nflat bands, sharply peaked densities of states (van Hove singularities, vHs),\nand intersecting Dirac cones near the Fermi energy (E$_F$). These N-doped\nLuH$_3$-based structures also exhibit an interconnected metallic hydrogen\nnetwork, which is a common feature of high-T$_c$ hydride superconductors.\nElectronic property systematics give estimates of T$_c$ for optimally ordered\nstructures that are well above the critical temperatures predicted for\nstructures considered previously. The vHs and flat bands near E$_F$ are\nenhanced in DFT+U calculations, implying strong correlation physics should also\nbe considered for first-principles studies of these materials. These results\nprovide a basis for understanding the novel electronic properties observed for\nnitrogen-doped lutetium hydride.",
        "positive": "Neutron photocrystallography: simulation and experiment: The investigation of light-induced structural changes by diffractive methods\nhas improved much in the last two decades. We present here the case of neutron\nphotocrystallography for which we have built a special experimental setup at\nthe single crystal neutron diffractometer TriCS at the Swiss Spallation Neutron\nSource SINQ. We illustrate the progress of the method on the example of the\nstructural determination of photoinduced nitrosyl linkage-isomers in\nNa2[Fe(CN)5NO] 2H2O. The in-situ determination of the population of the\nlight-induced linkage isomers by optical transmission measurements enhances the\nreliability of such structural investigations considerably. Additionally we\npresent a new simulation tool within the program package JANA2006 which allows\nto plan a photocrystallographic experiment thoroughly since the required\nq-range, the minimally needed population of the photoinduced species, as well\nas the necessary counting statistics for a successful single crystal\ndiffraction experiment can be evaluated in advance."
    },
    {
        "anchor": "Structural relationships among monoclinic and hexagonal phases and\n  transition structures in Mg-Zn-Y alloys: Isothermal ageing of plastically deformed Mg-Zn-Y alloys resulted in\nprecipitation along {10-12} twin boundaries. The bulky precipitates formed had\nstructures similar to those recently reported for the rod-like \\beta'\nprecipitates, but afforded a more detailed study by high resolution TEM due to\ntheir larger size. The core of the precipitates often had the structure of\nmonoclinic Mg4Zn7 phase, and had the orientation [0001]_Mg//[010]; {10-10}_Mg\n// (201) with either the matrix or the twin. On this Mg4Zn7 phase, hexagonal\nMgZn2 phase grew in two orientations, both with [010]_Mg4Zn7 // [11-20]_MgZn2.\nOne of these orientations formed a known orientation relationship [0001]_Mg //\n[11-20]_MgZn2; {11-20}_Mg // (0001)_MgZn2 with the matrix. The part of the\nprecipitate with the MgZn2 structure was usually in direct contact with the\ntwin boundary. Both Mg4Zn7 and MgZn2 phases have layered structures that can be\ndescribed with similar building blocks of icosahedrally coordinated atoms. The\natomic positions of zinc atoms comprise the vertices of these icosahedra and\nform \"thick\" rhombic tiles. Orientation of these rhombuses remain unchanged\nacross the interfaces between the two phases. Near the interface with MgZn2,\ntransition structures formed in Mg4Zn7 phase, with Zn:Mg atom ratio between\nthose of Mg4Zn7 and MgZn2 phases. In these transition structures, the unit cell\nof Mg4Zn7 phase is extended along [100] or [001] by half a unit cell length by\ncontinuation of the rhombic tiling. Structures of these extended unit cells are\nproposed.",
        "positive": "Franck-Condon Factors as Spectral Probes of Polaron Structure: We apply the Merrifield variational method to the Holstein molecular crystal\nmodel in D dimensions to compute non-adiabatic polaron band energies and\nFranck-Condon factors at general crystal momenta. We analyze these observable\nproperties to extract characteristic features related to polaron self-trapping\nand potential experimental signatures. These results are combined with others\nobtained by the Global-Local variational method in 1D to construct a polaron\nphase diagram encompassing all degrees of adiabaticity and all electron-phonon\ncoupling strengths. The polaron phase diagram so constructed includes disjoint\nregimes occupied by \"small\" polarons, \"large\" polarons, and a newly-defined\nclass of \"compact\" polarons, all mutually separated by an intermediate regime\noccupied by transitional structures."
    },
    {
        "anchor": "Hydrogen on graphene under stress: Molecular dissociation and gap\n  opening: Density functional calculations are employed to study the molecular\ndissociation of hydrogen on graphene, the diffusion of chemisorbed atomic\nspecies, and the electronic properties of the resulting hydrogen on graphene\nsystem. Our results show that applying stress to the graphene substrate can\nlower the barrier to dissociation of molecular hydrogen by a factor of six, and\nchange the process from endothermic to exothermic. These values for the barrier\nand the heat of reaction, unlike the zero stress values, are compatible with\nthe time scales observed in experiments. Diffusion, on the other hand, is not\ngreatly modified by stress. We analyse the electronic structure for\nconfigurations relevant to molecular dissociation and adsorption of atomic\nhydrogen on a graphene single layer. An absolute band gap of 0.5 eV is found\nfor the equilibrium optimum configuration for a narrow range of coverages\n($\\theta \\approx 0.25$). This value is in good agreement with experiment [Elias\net al., Science {\\bf 323}, 610 (2009)].",
        "positive": "Phase Diagram of Electron Doped Dichalcogenides: Using first principle calculations, we examine the sequence of phases in\nelectron doped dichalcogenides, such as recently realized in field-gated\nMoS$_2$. Upon increasing the electron doping level, we observe a succession of\nsemiconducting, metallic, superconducting and charge density wave regimes, i.e.\nin different order compared to the phase diagram of (semi-)metallic\ndichalcogenides such as TiSe$_2$. Both instabilities trace back to a softening\nof phonons which couple the electron populated conduction band minima. The\nsuperconducting dome, calculated using Eliashberg theory, is found to fit the\nexperimentally observed phase diagram, obtained from resistivity measurements.\nThe charge density wave phase at higher electron doping concentrations as\npredicted from instabilities in the phonon modes is further corroborated by\ndetecting the accompanying lattice deformation in density functional based\nsupercell relaxations. Upon charge density wave formation, doped MoS$_2$\nremains metallic but undergoes a Lifschitz transition, where the number of\nFermi pockets is reduced."
    },
    {
        "anchor": "Dzyaloshinskii-Moriya interaction and magnetic skyrmions induced by\n  curvature: Realizing sizeable Dzyaloshinskii-Moriya interaction (DMI) in intrinsic\ntwo-dimensional (2D) magnets without any manipulation will greatly enrich\npotential application of spintronics devices. The simplest and most desirable\nsituation should be 2D magnets with intrinsic DMI and intrinsic chiral spin\ntextures. Here, we propose to realize DMI by designing periodic ripple\nstructures with different curvatures in low-dimensional magnets and demonstrate\nthe concept in both one-dimensional (1D) CrBr2 and two-dimensional (2D) MnSe2\nmagnets by using first-principles calculations. We find that DMIs in curved\nCrBr2 and MnSe2 can be efficiently controlled by varying the size of curvature\nc, where c is defined as the ratio between the height h and the length l of\ncurved structure. Moreover, we unveil that the dependence of first-principles\ncalculated DMI on size of curvature c can be well described by the three-site\nFert-L\\'evy model. At last, we uncover that field-free magnetic skyrmions can\nbe realized in curved MnSe2 by using atomistic spin model simulations based on\nfirst-principles calculated magnetic parameters. The work will open a new\navenue for inducing DMI and chiral spin textures in simple 2D magnets via\ncurvature.",
        "positive": "Interatomic potentials for mixed oxide (MOX) nuclear fuels: We extend our recently developed interatomic potentials for UO_{2} to the\nmixed oxide fuel system (U,Pu,Np)O_{2}. We do so by fitting against an\nextensive database of ab initio results as well as to experimental\nmeasurements. The applicability of these interactions to a variety of mixed\nenvironments beyond the fitting domain is also assessed. The employed formalism\nmakes these potentials applicable across all interatomic distances without the\nneed for any ambiguous splining to the well-established short-range\nZiegler-Biersack-Littmark universal pair potential. We therefore expect these\nto be reliable potentials for carrying out damage simulations (and Molecular\nDynamics simulations in general) in nuclear fuels of varying compositions for\nall relevant atomic collision energies."
    },
    {
        "anchor": "Phase-field model for grain boundary grooving in multi-component thin\n  films: Polycrystalline thin films can be unstable with respect to island formation\n(agglomeration) through grooving where grain boundaries intersect the free\nsurface and/or thin film-substrate interface. We develop a phase-field model to\nstudy the evolution of the phases, composition, microstructure and morphology\nof such thin films. The phase-field model is quite general, describing\ncompounds and solid solution alloys with sufficient freedom to choose\nsolubilities, grain boundary and interface energies, and heats of segregation\nto all interfaces. We present analytical results which describe the interface\nprofiles, with and without segregation, and confirm them using numerical\nsimulations. We demonstrate that the present model accurately reproduces the\ntheoretical grain boundary groove angles both at and far from equilibrium. As\nan example, we apply the phase-field model to the special case of a Ni(Pt)Si\n(Ni/Pt silicide) thin film on an initially flat silicon substrate.",
        "positive": "Local step-flow dynamics in thin film growth with desorption: Desorption of deposited species plays a role in determining the evolution of\nsurface morphology during crystal growth when the desorption time constant is\nshort compared to the time to diffuse to a defect site, step edge or kink.\nHowever, experiments to directly test the predictions of these effects are\nlacking. Novel techniques such as \\emph{in-situ} coherent X-ray scattering can\nprovide significant new information. Herein we present X-ray Photon Correlation\nSpectroscopy (XPCS) measurements during diindenoperylene (DIP) vapor deposition\non thermally oxidized silicon surfaces. DIP forms a nearly complete\ntwo-dimensional first layer over the range of temperatures studied (40 - 120\n$^{\\circ}$C), followed by mounded growth during subsequent deposition. Local\nstep flow within mounds was observed, and we find that there was a\nterrace-length-dependent behavior of the step edge dynamics. This led to\nunstable growth with rapid roughening ($\\beta>0.5$) and deviation from a\nsymmetric error-function-like height profile. At high temperatures, the grooves\nbetween the mounds tend to close up leading to nearly flat polycrystalline\nfilms. Numerical analysis based on a 1 + 1 dimensional model suggests that\nterrace-length dependent desorption of deposited ad-molecules is an essential\ncause of the step dynamics, and it influences the morphology evolution."
    },
    {
        "anchor": "Epitaxial growth of a two-dimensional topological insulator candidate:\n  monolayer Si2Te2: Hexagonal Si2Te2 monolayers (ML-Si2Te2) were predicted to show\nstrain-dependent band-crossover between semiconducting and room-temperature\nquantum spin Hall phases. However, investigations on this artificial\ntwo-dimensional (2D) material have mainly been restricted to theoretical\ncalculations because its bulk counterpart does not exist naturally. Here, we\nreport on the successful epitaxial growth of ML-Si2Te2 films on Sb2Te3 thin\nfilm substrates. High-quality (1*1) ML-Si2Te2 films with a coverage as high as\n95% were obtained as revealed by scanning tunneling microscopy. X-ray\nphotoelectron spectroscopy confirms the absence of intermixing between Si2Te2\nand Sb2Te3 at the interface. By combining scanning tunneling spectroscopy with\ndensity functional theory calculations, we demonstrate the semiconducting band\nstructure of ML-Si2Te2 on Sb2Te3. Furthermore, it is theoretically predicted\nthat the system can be driven into the nontrivial phase via reducing the strain\nby 4.4% using strain engineering. Our results pave the way for in-depth\ninvestigations on this 2D topological insulator candidate.",
        "positive": "Systematic pathway generation and sorting in martensitic\n  transformations: Titanium alpha to omega: Structural phase transitions are governed by the underlying atomic\ntransformation mechanism; martensitic transformations can be separated into\nstrain and shuffle components. A systematic pathway generation and sorting\nalgorithm is presented and applied to the problem of the titanium alpha to\nomega transformation under pressure. In this algorithm, all pathways are\nconstructed within a few geometric limits, and efficiently sorted by their\nenergy barriers. The geometry and symmetry details of the seven lowest energy\nbarrier pathways are given. The lack of a single simple geometric criterion for\ndetermining the lowest energy pathway shows the necessity of atomistic studies\nfor pathway determination."
    },
    {
        "anchor": "Elasticity of sphere packings: pressure and initial state dependence: Elastic properties and internal states of isotropic sphere packings are\nstudied by numerical simulations. Several numerical protocols to assemble dense\nconfigurations are compared. One, which imitates experiments with lubricated\ncontacts, produces well coordinated states, while another, mimicking the effect\nof vibrations, results, for the same density, in a much smaller coordination\nnumber z, as small as in much looser systems. Upon varying the confining\npressure P, simulations show a very nearly reversible variation of density,\nwhile z is irreversibly changed in a pressure cycle. Elastic moduli are shown\nto be mainly related to the coordination number. Their P dependence notably\ndeparts from predictions of simple homogenization approaches in the case of the\nshear moduli of poorly coordinated systems.",
        "positive": "Phonons in ultrathin oxide films - 2D to 3D transition in FeO on Pt(111): The structural and magnetic properties of ultrathin FeO(111) films on Pt(111)\nwith thicknesses from 1 to 16 monolayers (ML) were studied using the nuclear\ninelastic scattering (NIS) of synchrotron radiation. Distinct evolution of\nvibrational characteristics with thickness that is revealed in the phonon\ndensity of states (PDOS) witnesses a textbook transition from 2D to 3D lattice\ndynamics. For the thinnest films of 1 and 2 ML, the low energy part of the PDOS\nfollowed a linear dependence in energy that is characteristic for 2-dimensional\nsystems. This dependence gradually transforms with thickness to the bulk\n~E-square relation. Density functional theory phonon calculations perfectly\nreproduced the measured 1 ML PDOS within a simple model of a pseudomorphic\nFeO/Pt(111) interface. The calculations show that the 2D PDOS character is due\nto a weak coupling of the FeO film to the Pt(111) substrate. The evolution of\nthe vibrational properties with an increasing thickness is closely related to a\ntransient long range magnetic order and stabilization of an unusual structural\nphase."
    },
    {
        "anchor": "Understanding the different exciton-plasmon coupling regimes in\n  two-dimensional semiconductors coupled with plasmonic lattices: a combined\n  experimental and unified equations of motion approach: We study exciton-plasmon coupling in two-dimensional semiconductors coupled\nwith Ag plasmonic lattices via angle-resolved reflectance spectroscopy and by\nsolving the equations of motion (EOMs) in a coupled oscillator model accounting\nfor all the resonances of the system. Five resonances are considered in the EOM\nmodel: semiconductor A and B excitons, localized surface plasmon resonances\n(LSPRs) of plasmonic nanostructures and the lattice diffraction modes of the\nplasmonic array. We investigated the exciton-plasmon coupling in different 2D\nsemiconductors and plasmonic lattice geometries, including monolayer MoS2 and\nWS2 coupled with Ag nanodisk and bowtie arrays, and examined the dispersion and\nlineshape evolution in the coupled systems via the EOM model with different\nexciton-plasmon coupling parameters. The EOM approach provides a unified\ndescription of the exciton-plasmon interaction in the weak, intermediate and\nstrong coupling cases with correctly explaining the dispersion and lineshapes\nof the complex system. This study provides a much deeper understanding of\nlight-matter interactions in multilevel systems in general and will be useful\nto instruct the design of novel two-dimensional exciton-plasmonic devices for a\nvariety of optoelectronic applications with precisely tailored responses.",
        "positive": "Absorption bias: An ideal descriptor for radiation tolerance of\n  nanocrystalline BCC metals: To evaluate the radiation tolerance of nanocrystalline (NC) materials, the\ndamage effects of Fe and W as typical body-centered cubic (BCC) metals under\nuniform irradiation are studied by a sequential multi-scale modelling\nframework. An ideal descriptor, the absorption bias (the ratio of the\nabsorption abilities of grain boundaries (GBs) to interstitials (I) and\nvacancies (V)), is proposed to characterize the radiation tolerance of\nmaterials with different grain sizes. Low absorption bias promotes defects\nannihilation through enhancing I-V recombination and optimally tuning its\ncompetition with GB absorption. Thus, the lower absorption bias, the higher\nanti-irradiation performance of NC BCC metals is. Furthermore, by\ncomprehensively considering the mechanical property, thermal stability and\nradiation resistance, nano-crystals are recommended for Fe-based structural\nmaterials but coarse crystals for W-based plasma-facing materials. This work\nreevaluates the radiation resistance of NC materials, resulting in new\nstrategies for designing structural materials of nuclear devices through\nmanipulating grain sizes."
    },
    {
        "anchor": "Effect of strain on the electronic and magnetic properties of bilayer\n  T-phase VS2: A first-principles study: Using the Density Functional Theory (DFT) calculations, we determined the\nelectronic and magnetic properties of a T-phase VS$_2$ bilayer as a function of\ntensile and compressive strain. First, we determine the ground state structural\nparameters and then the band structure, magnetic anisotropy, exchange\nparameters, and Curie temperature. Variation of these parameters with the\nstrain is carefully analyzed and described. The easy-plane anisotropy, which is\nrather small in the absence of strain, becomes remarkably enhanced by tensile\nstrain and reduced almost to zero by compressive strain. We also show that the\nexchange parameters and the Curie temperature are remarkably reduced for the\ncompressive strains below roughly -4$\\%$.",
        "positive": "Infrared study of the multiband low-energy excitations of the\n  topological antiferromagnet MnBi$_2$Te$_4$: With infrared spectroscopy we studied the bulk electronic properties of the\ntopological antiferromagnet MnBi$_2$Te$_4$ with $T_N \\simeq 25~\\mathrm{K}$.\nWith the support of band structure calculations, we assign the intra- and\ninterband excitations and determine the band gap of $E_g \\approx$ 0.17 eV. We\nalso obtain evidence for two types of conduction bands with light and very\nheavy carriers. The multiband free carrier response gives rise to an unusually\nstrong increase of the combined plasma frequency, $\\omega_{\\mathrm{pl}}$, below\n300 K. The band reconstruction below $T_N$, yields an additional increase of\n$\\omega_{\\mathrm{pl}}$ and a splitting of the transition between the two\nconduction bands by about 54 meV. Our study thus reveals a complex and strongly\ntemperature dependent multi-band low-energy response that has important\nimplications for the study of the surface states and device applications."
    },
    {
        "anchor": "Non-monotonic temperature dependence and first-order phase transition of\n  relaxation times in molecular spin: We derive a simple system of equations to describe the magnetization\nrelaxation of a molecular spin in weak interaction with a thermal bath for the\nwhole temperature domain. Using this for the intermediate temperature domain\nwhere the transition from coherent to incoherent relaxation occurs, we find\nthat the slowest relaxation mode shows a first-order phase transition.\nAssociated with this transition, an unusual non-monotonic\ntemperature-dependence of the relaxation rate of this mode is also\ndemonstrated. Contrary to the popular belief, this non-monotony gives rise to a\npeculiar but observable behavior where increasing temperature will not only\nresult in a smaller rate of the slowest relaxation mode but also may lead to a\nslower decaying of the magnetization after some relaxing time. Additionally, it\nis also shown that magnetization relaxation in this intermediate temperature\ndomain can only be accurately described by a bi- or tri-exponential form. The\nphysical reason underlying these features can be attributed to the role of the\nquantum tunneling effect and different but comparative relaxation modes. A\nsimple experiment to confirm our findings on the first-order phase transition\nand the non-monotony of the relaxation rate is accordingly proposed.",
        "positive": "On-Stack Two-Dimensional Conversion of MoS2 into MoO3: Chemical transformation of existing two-dimensional (2D) materials can be\ncrucial in further expanding the 2D crystal palette required to realize various\nfunctional heterostructures. In this work, we demonstrate a 2D 'on-stack'\nchemical conversion of single-layer crystalline MoS2 into MoO3 with a precise\nlayer control that enables truly 2D MoO3 and MoO3/MoS2 heterostructures. To\nminimize perturbation of the 2D morphology, a nonthermal oxidation using O2\nplasma was employed. The early stage of the reaction was characterized by a\ndefect-induced Raman peak, drastic quenching of photoluminescence (PL) signals\nand sub-nm protrusions in atomic force microscopy images. As the reaction\nproceeded from the uppermost layer to the buried layers, PL and optical second\nharmonic generation signals showed characteristic modulations revealing a\nlayer-by-layer conversion. The plasma-generated 2D oxides, confirmed as MoO3 by\nx-ray photoelectron spectroscopy, were found to be amorphous but extremely flat\nwith a surface roughness of 0.18 nm, comparable to that of 1L MoS2. The rate of\noxidation quantified by Raman spectroscopy decreased very rapidly for buried\nsulfide layers due to protection by the surface 2D oxides, exhibiting a\npseudo-self-limiting behavior. As exemplified in this work, various on-stack\nchemical transformations can be applied to other 2D materials in forming\notherwise unobtainable materials and complex heterostructures, thus expanding\nthe palette of 2D material building blocks."
    },
    {
        "anchor": "Laser-induced THz magnetization precession for a tetragonal Heusler-like\n  nearly compensated ferrimagnet: Laser-induced magnetization precessional dynamics was investigated in\nepitaxial films of Mn$_3$Ge, which is a tetragonal Heusler-like nearly\ncompensated ferrimagnet. The ferromagnetic resonance (FMR) mode was observed,\nthe precession frequency for which exceeded 0.5 THz and originated from the\nlarge magnetic anisotropy field of approximately 200 kOe for this ferrimagnet.\nThe effective damping constant was approximately 0.03. The corresponding\neffective Landau-Lifshitz constant of approximately 60 Mrad/s and is comparable\nto those of the similar Mn-Ga materials. The physical mechanisms for the\nGilbert damping and for the laser-induced excitation of the FMR mode were also\ndiscussed in terms of the spin-orbit-induced damping and the laser-induced\nultrafast modulation of the magnetic anisotropy, respectively.",
        "positive": "In-situ characterization of ultrathin nickel silicides using 3D\n  medium-energy ion scattering: We demonstrate a novel approach for non-destructive in-situ characterization\nof phase transitions of ultrathin nickel silicide films using 3D medium-energy\nion scattering. The technique provides simultaneously composition and\nreal-space crystallography of silicide films during the annealing process using\na single sample. We show, for 10 nm Ni films on Si, that their composition\nfollows the normal transition sequence, such as Ni-Ni2Si-NiSi. For samples with\ninitial Ni thickness of 3 nm, depth-resolved crystallography using a\nposition-sensitive detector, shows that the Ni film transform from an\nas-deposited disordered layer to epitaxial silicide layers at a relatively low\ntemperature of ~290 {\\deg}C."
    },
    {
        "anchor": "Ultrafast surface carrier dynamics in the topological insulator Bi2Te3: We discuss the ultrafast evolution of the surface electronic structure of the\ntopological insulator Bi$_2$Te$_3$ following a femtosecond laser excitation.\nUsing time and angle resolved photoelectron spectroscopy, we provide a direct\nreal-time visualisation of the transient carrier population of both the surface\nstates and the bulk conduction band. We find that the thermalization of the\nsurface states is initially determined by interband scattering from the bulk\nconduction band, lasting for about 0.5 ps; subsequently, few ps are necessary\nfor the Dirac cone non-equilibrium electrons to recover a Fermi-Dirac\ndistribution, while their relaxation extends over more than 10 ps. The surface\nsensitivity of our measurements makes it possible to estimate the range of the\nbulk-surface interband scattering channel, indicating that the process is\neffective over a distance of 5 nm or less. This establishes a correlation\nbetween the nanoscale thickness of the bulk charge reservoir and the evolution\nof the ultrafast carrier dynamics in the surface Dirac cone.",
        "positive": "Vibronic exciton theory of singlet fission. II. Two-dimensional\n  spectroscopic detection of the correlated triplet pair state: Singlet fission, the molecular process through which photons are effectively\nconverted into pairs of lower energy triplet excitons, holds promise as a means\nof boosting photovoltaic device efficiencies. In the preceding article of this\nseries, we formulated a vibronic theory of singlet fission, inspired by\nprevious experimental and theoretical studies suggesting that vibronic coupling\nplays an important role in fission dynamics. Here, we extend our model in order\nto simulate two-dimensional electronic spectra, through which the theory is\nfurther validated based on a comparison to recent measurements on pentacene\ncrystals. Moreover, by means of such spectral simulations, we provide new\ninsights into the nature of the correlated triplet pair state, the first\nproduct intermediate in the fission process. In particular, we address a\ndisagreement in the literature regarding the identification, energies, and\ntransition dipole moments of its optical transitions towards higher-lying\ntriplet states."
    },
    {
        "anchor": "Low-temperature Atomistic Spin Relaxation and Non-equilibrium Intensive\n  Properties Using Steepest-Entropy-Ascent Quantum-Inspired Thermodynamics\n  Modeling: The magnetization of body-centered cubic iron at low temperatures is\ncalculated with the steepest-entropy-ascent quantum thermodynamics (SEAQT)\nframework. This framework assumes that a thermodynamic property in an isolated\nsystem traces the path through state space with the greatest entropy\nproduction. Magnetization is calculated from the expected value of a\nthermodynamic ensemble of quantized spin waves based on the Heisenberg spin\nmodel applied to an ensemble of coupled harmonic oscillators. A realistic\nenergy landscape is obtained from a magnon dispersion relation calculated using\nspin-density-functional-theory. The equilibrium magnetization as well as the\nevolution of magnetization from a non-equilibrium state to equilibrium are\ncalculated from the path of steepest entropy ascent determined from the SEAQT\nequation of motion in state space. The framework makes it possible to model the\ntemperature- and time-dependence of magnetization without a detailed\ndescription of magnetic damping. The approach is also used to define intensive\nproperties (temperature and magnetic field strength) that are fundamentally,\ni.e., canonically or grand canonically, valid for any non-equilibrium state.\nGiven the assumed magnon dispersion relation, the SEAQT framework is used to\ncalculate the equilibrium magnetization at different temperatures and external\nmagnetic fields and the results are shown to closely agree with experiment for\ntemperatures less than 500 K. The time-dependent evolution of magnetization\nfrom different initial states and interactions with a reservoir is also\npredicted.",
        "positive": "Scanning tunneling microscopy study of Ni2MnGa(100) surface: Ni2MnGa(100) surface has been investigated in the premartensite and\nmartensite phase by using scanning tunneling microscopy. The presence of twined\nmorphology is observed in the premartensite phase for Mn excess surface which\nexhibit non-equispaced parallel bands in one side of the twin boundary.\nMoreover, in the flat region of the surface two domains of non-periodic\nparallel bands corresponding to the incommensurate CDW is observed. Although,\nstoichiometric surface also exhibit twining but the parallel bands are\nequispaced and have equal corrugation. Most interestingly, coexistence of\ntwined morphology and the CDW pattern is observed in the premartensite phase\nfor Ni excess surface which was not reported till date. In the martensite phase\nfor Mn excess surface, incommensurate CDW is transformed to commensurate CDW\ncorresponding to the equispaced parallel bands. In stark contrast,\nstoichiometric surface exhibit parallel bands that have different periodicity\nin different regions. Both the voltage dependent STM and STS measurement\nestablishes that this morphology is also related to the CDW."
    },
    {
        "anchor": "Decomposition of the spin-1/2 Heisenberg chain compound Sr2CuO3 in air\n  and water: An EPR and magnetic susceptibility study of Sr2Cu(OH)6: The reaction of Sr2CuO3 with air and liquid water was studied to address the\norigin of the reported variable Curie-Weiss impurity contribution to the\nmagnetic susceptibility X of this compound at low temperatures. Sr2CuO3 was\nfound to decompose upon exposure to either of these environments. The compound\nSr2Cu(OH)6 was identified as the primary reaction product. A pure sample of\nSr2Cu(OH)6 was then prepared separately. Electron paramagnetic resonance (EPR),\nisothermal magnetization versus magnetic field M(H) and X versus temperature T\nmeasurements demonstrate that Sr2Cu(OH)6 contains weakly interacting Cu+2\nmagnetic moments with spin S = 1/2 and average g-factor 2.133. From a fit of\nX(T) by the Curie-Weiss law and of the M(H) isotherms by modified Brillouin\nfunctions, the exchange interaction between adjacent Cu+2 spins was found to be\nJ/kB = -1.06(4)K, a weakly antiferromagnetic interaction. Our results indicate\nthat the previously reported, strongly sample-dependent, Curie-Weiss\ncontribution to X(T) of a polycrystalline Sr2CuO3 sample most likely arises\nfrom exposing the sample to air, resulting in a variable amount of paramagnetic\nSr2Cu(OH)6 on the surface of the sample.",
        "positive": "Soft X-ray spectro-ptychography on boron nitride nanotubes, carbon\n  nanotubes and permalloy nanorods: Spectro-ptychography offers improved spatial resolution and additional phase\nspectral information relative to that provided by scanning transmission X-ray\nmicroscopes (STXM). However, carrying out ptychography at the lower range of\nsoft X-ray energies (e.g., below 200 eV to 600 eV) on samples with weakly\nscattering signals can be challenging. We present soft X-ray ptychography\nresults at energies as low as 180 eV and illustrate the capabilities with\nresults from permalloy nanorods (Fe 2p), carbon nanotubes (C 1s), and boron\nnitride bamboo nanostructures (B 1s, N1s). We describe optimization of low\nenergy X-ray spectro-ptychography and discuss important challenges associated\nwith measurement approaches, reconstruction algorithms, and their effects on\nthe reconstructed images. A method for evaluating the increase in radiation\ndose when using overlapping sampling is presented."
    },
    {
        "anchor": "Spin Glass Behavior in the Dy3-xYxTaO7 System: Several x-compositions of the polycrystalline Dy3-xYxTaO7 system,\ncrystallizing in the weberite-type structure, were synthesized and structurally\ncharacterized using Rietveld refinements based on X-ray diffraction data. In\nprevious magnetic characterization of Dy3TaO7 (x = 0), with the same crystal\nstructure, an antiferromagnetic transition at T = 2.3 K has been assigned to\nthis compound. On the basis of DC and AC magnetic susceptibilities analyses, we\nshow in this work that all compounds in the x range of 0-1.0 exhibit a spin\nglass behavior. The nature of the spin glass behavior in Dy3-xYxTaO7, can be\nattributed to the highly frustrated antiferromagnetic interaction of the Dy3+\nsublattice and to the Dy3+-Dy3+ distorted tetrahedra array in the weberite-type\nstructure of this system. By fitting AC susceptibility data, using dynamical\nscaling theory equations, we conclude that a cluster spin glass is present in\nDy3-xYxTaO7 in the low temperature range. Depending on the x-composition, Tg ~\n2.2 - 3.2 K. In the range 15-300 K the system obeys a Curie-Weiss magnetic\nbehavior.",
        "positive": "The Memory-Conservation Theory of Memristance: The memristor, the recently discovered fundamental circuit element, is of\ngreat interest for neuromorphic computing, nonlinear electronics and computer\nmemory. It is usually modelled either using Chua's equations, which lack\nmaterial device properties, or using Strukov's phenomenological model (or\nmodels derived from it), which deviates from Chua's definitions due to the lack\nof a magnetic flux term. It is shown that by modelling the magnetostatics of\nthe memory-holding ionic current (oxygen vacancies in the Strukov memristor),\nthe memristor's magnetic flux can be identified as the flux arising from the\nions. This leads to a novel theory of memristance consisting of two components:\n1. A memory function which describes how the memristance, as felt by the ions,\naffects the conducting electrons located in the `on' part of the device; 2. A\nconservation function which describes the time-varying resistance in the `off'\npart of the device. This model allows for a straight-forward incorporation of\nthe ions within the electronic theory and relates Chua's constitutive\ndefinition of a memristor with device material properties for the first time."
    },
    {
        "anchor": "Temperature Dependent Magnetic Anisotropy in (Ga,Ma)As Layers: It is demonstrated by SQUID magnetization measurements that (Ga,Mn)As films\ncan exhibit rich characteristics of magnetic anisotropy depending not only to\nthe epitaxial strain but being strongly influenced by the hole and Mn\nconcentration, and temperature. This behavior reflects the spin anisotropy of\nthe valence subbands and corroborates predictions of the mean field Zener model\nof the carrier mediated ferromagnetism in III-V diluted magnetic semiconductors\nwith Mn. At the same time the existence of in-plane uniaxial anisotropy with\n[110] the easy axis is evidenced. This is related to the top/bottom symmetry\nbreaking, resulting in the lowering of point symmetry of (Ga,Mn)As to the\nC_{2v} symmetry group. The latter mechanism coexists with the hole-induced\ncubic anisotropy, but takes over close to T_C.",
        "positive": "Temperature-Induced Hexagonal-Orthorhombic Phase Transition in Lutetium\n  Ferrite Nanoparticles: The X-ray diffraction, Raman and infrared spectroscopies and magnetic\nmeasurements were used to explore the correlated changes of the structure,\nlattice dynamics and magnetic properties of the LuFeO3 nanoparticles, which\nappear in dependence on their sintering temperature. We revealed a gradual\nsubstitution of the hexagonal phase by the orthorhombic phase in the\nnanoparticles, which sintering temperature increases from 700 C to 1100 C. The\norigin and stability of the hexagonal phase in the LuFeO3 nanoparticles is of\nthe special interest, because the nanoparticle in the phase can be a\nroom-temperature multiferroic with a weak ferromagnetic and pronounced\nstructural and ferroelectric long-range ordering, while the antiferromagnetic\nand nonpolar orthorhombic phase is more stable in the bulk LuFeO3. To define\nthe ranges of the hexagonal phase stability, we determine the bulk and\ninterface energy densities of different phases from the comparison of the Gibbs\nmodel with experimental results. Using the Gibbs model parameters, we predict\nthe influence of size effects and temperature on the structural and polar\nproperties of the LuFeO3 nanoparticles. Analysis of the obtained results shows\nthat the combination of the X-ray diffraction, Raman and infrared spectroscopy,\nmagnetic measurements and theoretical modelling of structural and polar\nproperties allows to establish the interplay between the phase composition,\nlattice dynamics and multiferroic properties of the LuFeO3 nanoparticles\nprepared in different conditions."
    },
    {
        "anchor": "Low temperature acoustic polaron localization: We calculate the properties of an acoustic polaron in three dimensions in\nthermal equilibrium at a given low temperature using the path integral Monte\nCarlo method. The specialized numerical method used is described in full\ndetails, thus complementing our previous paper [R. Fantoni, Phys. Rev. B {\\bf\n86}, 144304 (2012)], and it appears to be the first time it has been used in\nthis context. Our results are in favor of the presence of a phase transition\nfrom a localized state to an extended state for the electron as the\nphonon-electron coupling constant decreases. The phase transition manifests\nitself with a jump discontinuity in the potential energy as a function of the\ncoupling constant and it affects the properties of the path of the electron in\nimaginary time: In the weak coupling regime the electron is in an extended\nstate whereas in the strong coupling regime it is found in a self-trapped\nstate.",
        "positive": "Amorphous Ferrimagnets: an Ideal Host for Ultra-Small Skyrmions at Room\n  Temperature: Recently, magnetic skyrmion has emerged as an active topic of fundamental\nstudy and applications in magnetic materials research. Magnetic skyrmions are\nvortex-like spin excitations with topological protection and therefore are more\nrobust to pinning compared with magnetic domain walls. We employ atomistic\nsimulations to create room-temperature ultra-small Neel skyrmions in amorphous\nferrimagnet. The fast propagation and low-dissipation dynamics of ultra-small\nferrimagnetic skyrmions make them attractive for utilization as an alternative\nto domain walls in spin-based memory and logic devices."
    },
    {
        "anchor": "The structure of CaSO4 nanorods -- the precursor of gypsum: Understanding the gypsum (CaSO4.2H2O) formation pathway from aqueous solution\nhas been the subject of intensive research in the past years. This interest\nstems from the fact that gypsum appears to fall into a broader category of\ncrystalline materials whose formation does not follow classical nucleation and\ngrowth theories. The pathways involve transitory precursor cluster species, yet\nthe actual structural properties of such clusters are not very well understood.\nHere, we show how in situ high-energy X-ray diffraction experiments and\nmolecular dynamics (MD) simulations can be combined to derive the structure of\nsmall CaSO4 clusters, which are precursors of crystalline gypsum. We fitted\nseveral plausible structures to the derived pair distribution functions and\nexplored their dynamic properties using unbiased MD simulations based on both\nrigid ion and polarizable force fields. Determination of the structure and\n(meta)stability of the primary species is important from both a fundamental and\napplied perspective; for example, this will allow for an improved design of\nadditives for greater control of the nucleation pathway.",
        "positive": "Semiconducting Characteristics of Magnesium-Doped Al2O3 Single Crystals: DC and AC electrical measurements were performed to investigate the\nelectrical conductivity of alpha-Al2O3:Mg samples with different concentrations\nof [Mg]^0 centers .The concentration of [Mg]^0 centers was monitored by the\nopticalabsorption peak at 2.56 eV. At low electrical fields, DC measurements\nreveal blocking contacts. Steady electroluminescence is emitted at the negative\nelectrodeindicating that the majority of carriers are holes. Low voltage AC\nmeasurements show that the equivalent circuit for the sample is the bulk\nresistance in series with the junction capacitance connected in parallel with a\ncapacitance, which represents the dielectric constant of the sample. The values\ndetermined for the bulk resistance in both DC and AC experiments are in good\nagreement. The electrical conductivity of Al2O3:Mg crystals increases linearly\nwith the concentration of [Mg]^0 centers, regardless of the amount of other\nimpurities also present in the crystals, and is four times higher in the\n$c_{\\perpendicular}$ than in the $c_{\\parallel}$ direction. The conductivity is\nthermally activated with an activation energy of 0.68 eV, which is independent\nof: 1) the [Mg]^0 content, 2) the crystallographic orientation, and 3) the\nconcentration of other impurities. These results favor the {\\it\nsmall-polaron-motion} mechanism."
    },
    {
        "anchor": "Non-adiabatic Effects in the Dissociation of Oxygen Molecules at the\n  Al(111) Surface: The measured low initial sticking probability of oxygen molecules at the\nAl(111) surface that had puzzled the field for many years was recently\nexplained in a non-adiabatic picture invoking spin-selection rules [J. Behler\net al., Phys. Rev. Lett. 94, 036104 (2005)]. These selection rules tend to\nconserve the initial spin-triplet character of the free O2 molecule during the\nmolecule's approach to the surface. A new locally-constrained\ndensity-functional theory approach gave access to the corresponding\npotential-energy surface (PES) seen by such an impinging spin-triplet molecule\nand indicated barriers to dissociation which reduce the sticking probability.\nHere, we further substantiate this non-adiabatic picture by providing a\ndetailed account of the employed approach. Building on the previous work, we\nfocus in particular on inaccuracies in present-day exchange-correlation\nfunctionals. Our analysis shows that small quantitative differences in the\nspin-triplet constrained PES obtained with different gradient-corrected\nfunctionals have a noticeable effect on the lowest kinetic energy part of the\nresulting sticking curve.",
        "positive": "Correlating Structural, Electronic, and Magnetic Properties of Epitaxial\n  VSe2 Thin Films: The electronic and magnetic properties of transition metal dichalcogenides\nare known to be extremely sensitive to their structure. In this paper we study\nthe effect of structure on the electronic and magnetic properties of mono- and\nbilayer $VSe_2$ films grown using molecular beam epitaxy. $VSe_2$ has recently\nattracted much attention due to reports of emergent ferromagnetism in the 2D\nlimit. To understand this important compound, high quality 1T and distorted 1T\nfilms were grown at temperatures of 200 $^\\text{o}$C and 450 $^\\text{o}$C\nrespectively and studied using 4K Scanning Tunneling Microscopy/Spectroscopy.\nThe measured density of states and the charge density wave (CDW) patterns were\ncompared to band structure and phonon dispersion calculations. Films in the 1T\nphase reveal different CDW patterns in the first layer compared to the second.\nInterestingly, we find the second layer of the 1T-film shows a CDW pattern with\n4a $\\times$ 4a periodicity which is the 2D version of the bulk CDW observed in\nthis compound. Our phonon dispersion calculations confirm the presence of a\nsoft phonon at the correct wavevector that leads to this CDW. In contrast, the\nfirst layer of distorted 1T phase films shows a strong stripe feature with\nvarying periodicities, while the second layer displays no observable CDW\npattern. Finally, we find that the monolayer 1T $VSe_2$ film is weakly\nferromagnetic, with ~ $3.5 {\\mu}_B$ per unit similar to previous reports."
    },
    {
        "anchor": "Effects of high energy electron irradiation on quantum emitters in\n  hexagonal boron nitride: Hexagonal Boron Nitride (hBN) mono and multilayers are promising hosts for\nroom temperature single photon emitters (SPEs). In this work we explore high\nenergy (~ MeV) electron irradiation as a means to generate stable SPEs in hBN.\nWe investigate four types of exfoliated hBN flakes - namely, high purity\nmultilayers, isotopically pure hBN, carbon rich hBN multilayers and monolayered\nmaterial - and find that electron irradiation increases emitter concentrations\ndramatically in all samples. Furthermore, the engineered emitters are located\nthroughout hBN flakes (not only at flake edges or grain boundaries), and do not\nrequire activation by high temperature annealing of the host material after\nelectron exposure. Our results provide important insights into controlled\nformation of hBN SPEs and may aid in identification of their crystallographic\norigin.",
        "positive": "Probing the uniaxial strains in MoS$_2$ using polarized Raman\n  spectroscopy: A first-principles study: Characterization of strain in two-dimensional (2D) crystals is important for\nunderstanding their properties and performance. Using first-principles\ncalculations, we study the effects of uniaxial strain on the Raman-active modes\nin monolayer MoS$_2$. We show that the in-plane $E'$ mode at 384 cm$^{-1}$ and\nthe out-of-plane $A_1'$ mode at 403 cm$^{-1}$ can serve as fingerprints for the\nuniaxial strain in this 2D material. Specifically, under a uniaxial strain, the\ndoubly degenerate $E'$ mode splits into two non-degenerate modes: one is\n$E_{\\parallel}'$ mode in which atoms vibrate in parallel to the strain\ndirection, and the other is $E_\\perp'$ mode in which atoms vibrate\nperpendicular to the strain direction. The frequency of the $E_{\\parallel}'$\nmode blue-shifts for a compressive strain, but red-shifts for a tensile strain.\nIn addition, due to the strain-induced anisotropy in the MoS$_2$ lattice, the\npolarized Raman spectra of the $E_{\\parallel}'$ and $E_{\\perp}'$ modes exhibit\ndistinct angular dependence for specific laser polarization setups, allowing\nfor a precise determination of the direction of the uniaxial strain with\nrespect to the crystallographic orientation. Furthermore, we find that the\npolarized Raman intensity of the $A_1'$ mode also shows evident dependence on\nthe applied strain, providing additional effective clues for determining the\ndirection of the strain even without knowledge of the crystallographic\norientation. Thus, polarized Raman spectroscopy offers an efficient\nnon-destructive way to characterize the uniaxial strains in monolayer MoS$_2$."
    },
    {
        "anchor": "Variable-Order Fracture Mechanics and its Application to Dynamic\n  Fracture: This study presents the formulation, the numerical solution, and the\nvalidation of a theoretical framework based on the concept of variable-order\nmechanics and capable of modeling dynamic fracture in brittle and quasi-brittle\nsolids. More specifically, the reformulation of the elastodynamic problem via\nvariable and fractional order operators enables a unique and extremely powerful\napproach to model nucleation and propagation of cracks in solids under dynamic\nloading. The resulting dynamic fracture formulation is fully evolutionary hence\nenabling the analysis of complex crack patterns without requiring any a prior\nassumptions on the damage location and the growth path, as well as the use of\nany algorithm to track the evolving crack surface. The evolutionary nature of\nthe variable-order formalism also prevents the need for additional partial\ndifferential equations to predict the damage field, hence suggesting a\nconspicuous reduction in the computational cost. Remarkably, the variable order\nformulation is naturally capable of capturing extremely detailed features\ncharacteristic of dynamic crack propagation such as crack surface roughening,\nsingle and multiple branching. The accuracy and robustness of the proposed\nvariable-order formulation is validated by comparing the results of direct\nnumerical simulations with experimental data of typical benchmark problems\navailable in the literature.",
        "positive": "Co-orchestration of Multiple Instruments to Uncover Structure-Property\n  Relationships in Combinatorial Libraries: The rapid growth of automated and autonomous instrumentations brings forth an\nopportunity for the co-orchestration of multimodal tools, equipped with\nmultiple sequential detection methods, or several characterization tools to\nexplore identical samples. This can be exemplified by the combinatorial\nlibraries that can be explored in multiple locations by multiple tools\nsimultaneously, or downstream characterization in automated synthesis systems.\nIn the co-orchestration approaches, information gained in one modality should\naccelerate the discovery of other modalities. Correspondingly, the\norchestrating agent should select the measurement modality based on the\nanticipated knowledge gain and measurement cost. Here, we propose and implement\na co-orchestration approach for conducting measurements with complex\nobservables such as spectra or images. The method relies on combining\ndimensionality reduction by variational autoencoders with representation\nlearning for control over the latent space structure, and integrated into\niterative workflow via multi-task Gaussian Processes (GP). This approach\nfurther allows for the native incorporation of the system's physics via a\nprobabilistic model as a mean function of the GP. We illustrated this method\nfor different modalities of piezoresponse force microscopy and micro-Raman on\ncombinatorial $Sm-BiFeO_3$ library. However, the proposed framework is general\nand can be extended to multiple measurement modalities and arbitrary\ndimensionality of measured signals. The analysis code that supports the funding\nis publicly available at https://github.com/Slautin/2024_Co-orchestration."
    },
    {
        "anchor": "Room-temperature synthesis of graphene-like carbon sheets from C2H2, CO2\n  and CO on copper foils: A high temperature for some catalytic reactions like synthesis of large area\nand high quality graphene is required. The mentioned graphene can be obtained\nby a chemical vapour deposition (CVD) process on copper foil at 800 1000. Here,\nwe describe a room temperature synthesis method from different carbon sources\nfor the first time, including acetylene, carbon dioxide and carbon monoxide, on\ncopper foil by using a heuristic method which was inspired from the role of\nsome electronic promoters in catalyst science. Promoters are substances that\nincrease the catalytic activity, but they are not catalysts by themselves. In\nthis study, we used charges to modify the electronic effects of the catalysts,\nwhich were produced by piezoelectric materials.",
        "positive": "A possible mechanism of ultrafast amorphization in phase-change memory\n  alloys: an ion slingshot from the crystalline to amorphous position: We propose that the driving force of an ultrafast crystalline-to-amorphous\ntransition in phase-change memory alloys are strained bonds existing in the\n(metastable) crystalline phase. For the prototypical example of GST, we\ndemonstrate that upon breaking of long Ge-Te bond by photoexcitation Ge ion\nshot from an octahedral crystalline to a tetrahedral amorphous position by the\nuncompensated force of strained short bonds. Subsequent lattice relaxation\nstabilizes the tetrahedral surroundings of the Ge atoms and ensures the\nlong-term stability of the optically induced phase."
    },
    {
        "anchor": "Small-mass atomic defects enhance vibrational thermal transport at\n  disordered interfaces with ultrahigh thermal boundary conductance: The role of interfacial nonidealities and disorder on thermal transport\nacross interfaces is traditionally assumed to add resistance to heat transfer,\ndecreasing the thermal boundary conductance (TBC).$^1$ However, recent\ncomputational works have suggested that interfacial defects can enhance this\nthermal boundary conductance through emergence of unique vibrations that are\nintrinsic to the material interface and defect atoms,$^{2-6}$ a finding that\ncontradicts traditional theory and conventional understanding. By manipulating\nthe local heat flux of atomic vibrations that comprise these interfacial modes,\nin principle, the TBC can be increased. In this work, we provide evidence that\ninterfacial defects can enhance the TBC across interfaces through the emergence\nof unique high frequency vibrational modes that arise from atomic mass defects\nat the interface with relatively small masses. We demonstrate ultrahigh TBC at\namorphous SiOC:H/SiC:H interfaces, approaching 1 GW m$^{-2}$ K$^{-1}$, that is\nfurther increased through the introduction of nitrogen defects. The fact that\ndisordered interfaces can exhibit such high conductances, which can be further\nincreased with additional defects offers a unique direction in controlling\ninterfacial thermal transport that becomes important in manipulating heat\ntransfer across materials with high densities of interfaces.",
        "positive": "\\emph{Ab initio} theory of $\\text{N}_{2}\\text{V}$ defect as quantum\n  memory in diamond: $\\text{N}_{2}\\text{V}$ defect in diamond is characterized by means of\n\\emph{ab initio} methods relying on density functional theory calculated\nparameters of a Hubbard model Hamiltonian. It is shown that this approach\nappropriately describes the energy levels of correlated excited states induced\nby this defect. By determining its critical magneto-optical parameters, we\npropose to realize a long-living quantum memory by $\\text{N}_{2}\\text{V}$\ndefect in diamond."
    },
    {
        "anchor": "Reaction-Drift Model for Switching Transients in\n  Pr$_{0.7}$Ca$_{0.3}$MnO$_3$ Based Resistive RAM: Earlier, the DC hole-current modeling of PCMO RRAM by drift-diffusion (DD)\nincluding self-heating (SH) in TCAD (but without ionic transport) was able to\nexplain the experimentally observed SCLC characteristics, prior to resistive\nswitching. Further, transient analysis using DD+SH model was able to reproduce\nthe experimentally observed fast current increase at ~100ns timescale followed\nby saturation increases, prior to resistive switching. However, resistive\nswitching requires the inclusion of ionic transport. We propose a\nReaction-Drift (RD) model of oxide ions, which is combined with the DD+SH\nmodel. Experimentally, SET operations consist of 3 stages and RESET operations\nconsists of 4 stages. The DD+SH+RD model is able to reproduce the entire\ntransient behavior over 10$^{-8}$-1s range in timescale for both SET and RESET\noperations for a range of bias, temperature. Remarkably, a universal RESET\nbehaviour of $log(I)\\propto m*log(t)$, where $m\\approx -1/10$, is reproduced.\nThe quantitatively different voltage time dilemma for SET and RESET is also\nreplicated for a range of ambient temperature. This demonstrates a\ncomprehensive model for resistance switching in PCMO based RRAM.",
        "positive": "Kagome modes, a new route to ultralow thermal conductivity?: From next generation gas turbines to scavenging waste heat from car exhausts,\nfinding new materials with ultra-low thermal conductivity ($\\kappa$) has the\npotential to lead to large gains in device efficiency. Crystal structures with\ninherently low $\\kappa$ are consequently desirable, but candidate materials are\nrare and often difficult to make. Using first principles calculations and\ninelastic neutron scattering we have studied the pyrochlore La$_2$Zr$_2$O$_7$\nwhich has been proposed as a next generation thermal barrier. We find that\nthere is a highly anharmonic, approximately flat, vibrational mode associated\nwith the kagome planes. Our results suggest that this mode is responsible for\nthe low thermal conductivity observed in the pyrochlores and that kagome\ncompounds will be a fruitful place to search for other low $\\kappa$ materials."
    },
    {
        "anchor": "Presence of a (1x1) oxygen overlayer on bare ZnO(0001) surfaces and at\n  Schottky interfaces: The atomic surface and interface structure of bare and metal-coated ZnO(0001)\nZn-polar wafers were investigated via surface x-ray diffraction. All bare\nsamples showed the presence of a (1x1) overlayer of oxygen atoms located at the\non-top position above the terminating Zn atom, a structure predicted to be\nunstable by several density functional theory calculations. The same oxygen\noverlayer is clearly seen at the interface of ZnO with both elemental and\noxidized metal contact layers. No significant atomic relaxations are observed\nat surfaces and interfaces processed under typical device fabrication\nconditions.",
        "positive": "Glass transition theory based on stress relaxation: We propose that an onset of glass transition can be defined as the point at\nwhich a supercooled liquid acquires the stress relaxation mechanism of a solid\nglass. We translate this condition into the rate equation for local relaxation\nevents. This equation simultaneously gives two main signatures of glass\ntransition, stretched-exponential relaxation and the Vogel-Fulcher law. The\nproposed theory quantifies system fragility in terms of the number of retarded\nlocal relaxation events and reproduces its correlation with the\nnon-exponentiality of relaxation and bonding type."
    },
    {
        "anchor": "Discovery of ferromagnetism with large magnetic anisotropy in ZrMnP and\n  HfMnP: ZrMnP and HfMnP single crystals are grown by a self-flux growth technique and\nstructural as well as temperature dependent magnetic and transport properties\nare studied. Both compounds have an orthorhombic crystal structure. ZrMnP and\nHfMnP are ferromagnetic with Curie temperatures around $370$~K and $320$~K\nrespectively. The spontaneous magnetizations of ZrMnP and HfMnP are determined\nto be $1.9$~$\\mu_\\textrm{B}$/f.u. and $2.1$~$\\mu_\\textrm{B}$/f.u. respectively\nat $50$~K. The magnetocaloric effect of ZrMnP in term of entropy change\n($\\Delta S$) is estimated to be $-6.7$ kJm$^{-3}$K$^{-1}$ around $369$~K. The\neasy axis of magnetization is [100] for both compounds, with a small anisotropy\nrelative to the [010] axis. At $50$~K, the anisotropy field along the [001]\naxis is $\\sim4.6$~T for ZrMnP and $\\sim10$~T for HfMnP. Such large magnetic\nanisotropy is remarkable considering the absence of rare-earth elements in\nthese compounds. The first principle calculation correctly predicts the\nmagnetization and hard axis orientation for both compounds, and predicts the\nexperimental HfMnP anisotropy field within 25 percent. More importantly, our\ncalculations suggest that the large magnetic anisotropy comes primarily from\nthe Mn atoms suggesting that similarly large anisotropies may be found in other\n3d transition metal compounds.",
        "positive": "Generation of water-in-oil and oil-in-water microdroplets in\n  polyester-toner microfluidic devices: This paper demonstrates that disposable polyester-toner microfluidic devices\nare suitable to produce either water-in-oil (W/O) or oil-in-water (O/W)\ndroplets without using any surface treatment of the microchannels walls. Highly\nmonodisperse W/O and O/W emulsions were generated in T-junction microdevices by\nsimply adding appropriate surfactants to the continuous phase. The dispersion\nin size of droplets generated at frequencies up to 500 Hz was always less than\nabout 2% over time intervals of a couple of hours."
    },
    {
        "anchor": "Role of equilibrium fluctuations in light-induced order: Engineering novel states of matter with light is at the forefront of\nmaterials research. An intensely studied direction is to realize\nbroken-symmetry phases that are \"hidden\" under equilibrium conditions but can\nbe unleashed by an ultrashort laser pulse. Despite a plethora of experimental\ndiscoveries, the nature of these orders and how they transiently appear remain\nunclear. To this end, we investigate a nonequilibrium charge density wave (CDW)\nin rare-earth tritellurides, which is suppressed in equilibrium but emerges\nafter photoexcitation. Using a pump-pump-probe protocol implemented in\nultrafast electron diffraction, we demonstrate that the light-induced CDW\nconsists solely of order parameter fluctuations, which bear striking\nsimilarities to critical fluctuations in equilibrium despite differences in the\nlength scale. By calculating the dynamics of CDW fluctuations in a\nnonperturbative model, we further show that the strength of the light-induced\norder is governed by the amplitude of equilibrium fluctuations. These findings\nhighlight photoinduced fluctuations as an important ingredient for the\nemergence of transient orders out of equilibrium. Our results further suggest\nthat materials with strong fluctuations in equilibrium are promising platforms\nto host \"hidden\" orders after laser excitation.",
        "positive": "A dilute gold nanoparticles suspension as SAXS standard for absolute\n  scale using an extended Guinier approximation: In this article, a practical procedure for absolute intensity calibration for\nSAXS studies on liquid microjets is established, using a gold nanoparticle\nsuspension as standard so that the intercept at $Q=0$ of the SAXS scattering\ncurve would provide a scaling reference. In order to get the most precise\nextrapolation at $Q=0$, we used an extension to the Guinier approximation, with\na second-order term in the fit that adapts to a larger $Q$-range."
    },
    {
        "anchor": "Composition dependent band gap and band edge bowing in AlInN: A combined\n  theoretical and experimental study: A combined experimental and theoretical study is presented of the band gap of\nAlInN, confirming the breakdown of the virtual crystal approximation (VCA) for\nthe conduction and valence band edges. Composition dependent bowing parameters\nfor these quantities are extracted. Additionally, composition dependent band\noffsets for GaN/AlInN systems are provided. We show that local strain and\nbuilt-in fields affect the band edges significantly, leading to optical\npolarization switching at much lower In composition than expected from a VCA\napproach.",
        "positive": "Enhancing Perovskite Electrocatalysis through Strain Tuning of the\n  Oxygen Deficiency: Oxygen vacancies in transition metal oxides facilitate catalysis critical for\nenergy storage and generation. However, it has proven elusive to promote\nvacancies at the lower temperatures required for operation in devices such as\nmetal-air batteries and portable fuel cells. Here, we use thin films of the\nperovskite-based strontium cobaltite (SrCoOx) to show that epitaxial strain is\na powerful tool towards manipulating the oxygen content under conditions\nconsistent with the oxygen evolution reaction, yielding increasingly oxygen\ndeficient states in an environment where the cobaltite would normally be fully\noxidized. The additional oxygen vacancies created through tensile strain\nenhance the cobaltite catalytic activity towards this important reaction by\nover an order of magnitude, equaling that of precious metal catalysts,\nincluding IrO2. Our findings demonstrate that strain in these oxides can\ndictate oxygen stoichiometry independent of ambient conditions, allowing\nunprecedented control over oxygen vacancies essential in catalysis near room\ntemperature."
    },
    {
        "anchor": "Molecular weight effects on chain pull-out fracture of reinforced\n  polymeric interfaces: Using Brownian dynamics, we simulate the fracture of polymer interfaces\nreinforced by diblock connector chains. We find that for short chains the\ninterface fracture toughness depends linearly on the degree of polymerization\n$N$ of the connector chains, while for longer chains the dependence becomes\n$N^{3/2}$. Based on the geometry of initial chain configuration, we propose a\nscaling argument that accounts for both short and long chain limits and\ncrossover between them.",
        "positive": "Relevance of coordinate and particle-number scaling in density\n  functional theory: We discuss a $\\beta$-dependent family of electronic density scalings of the\nform $n_\\lambda(\\R)=\\lambda^{3\\beta+1}\\; n(\\lambda^\\beta \\R)$ in the context of\ndensity functional theory. In particular, we consider the following special\ncases: the Thomas-Fermi scaling ($\\beta=1/3$ and $\\lambda \\gg 1$), which is\ncrucial for the semiclassical theory of neutral atoms; the uniform-electron-gas\nscaling ($\\beta=-1/3$ and $\\lambda\\gg 1$), that is important in the\nsemiclassical theory of metallic clusters; the homogeneous density scaling\n($\\beta=0$) which can be related to the self-interaction problem in density\nfunctional theory when $\\lambda \\leq 1$; the fractional scaling ($\\beta=1$ and\n$\\lambda\\leq 1$), that is important for atom and molecule fragmentation; and\nthe strong-correlation scaling ($\\beta=-1$ and $\\lambda \\gg 1$) that is\nimportant to describe the strong correlation limit.\n  The results of our work provide evidence for the importance of this family of\nscalings in semiclassical and quantum theory of electronic systems, and\nindicate that these scaling properties must be considered as important\nconstraints in the construction of new approximate density functionals. We also\nshow, using the uniform-electron-gas scaling, that the curvature energy of\nmetallic clusters is related to the second-order gradient expansion of kinetic\nand exchange-correlation energies."
    },
    {
        "anchor": "Tuning of metal-insulator transition of two-dimensional electrons at\n  parylene/SrTiO$_3$ interface by electric field: Electrostatic carrier doping using a field-effect-transistor structure is an\nintriguing approach to explore electronic phases by critical control of carrier\nconcentration. We demonstrate the reversible control of the insulator-metal\ntransition (IMT) in a two dimensional (2D) electron gas at the interface of\ninsulating SrTiO$_3$ single crystals. Superconductivity was observed in a\nlimited number of devices doped far beyond the IMT, which may imply the\npresence of 2D metal-superconductor transition. This realization of a\ntwo-dimensional metallic state on the most widely-used perovskite oxide is the\nbest manifestation of the potential of oxide electronics.",
        "positive": "An Overview of Planar Flow Casting of Thin Metallic Glasses and its\n  Relation to Slot Coating of Liquid Films: Planar flow casting (PFC) is a method that can be used to make thin, long,\nand wide metallic alloy foils by extruding molten liquid through a thin and\nwide nozzle and immediately quenching on a moving roller. The quenching rates\nare high enough that amorphous metallic glasses may be formed which have many\ndesirable properties for a wide variety of applications. This paper reviews how\nPFC processes were developed, examines the typical operability range of PFC,\nand reviews the defects that commonly form. The geometrical similarities\nbetween PFC and slot coating process are apparent, and this paper highlights\ndifferences between the operability ranges of both processes."
    },
    {
        "anchor": "Reproduction of the electronic and magnetic structure of the low\n  symmetry sites of Y$_{2}$SiO$_{5}$ doped with Sm$^{3+}$ via a parameterized\n  crystal-field model: Parametrized crystal-field analyses are presented for both the six and seven\nfold coordinated, C$_{1}$ symmetry Sm$^{3+}$ centers in Y$_{2}$SiO$_{5}$, based\non extensive spectroscopic data spanning the infrared to optical regions. Laser\nsite-selective excitation and fluorescence spectroscopy as well as Zeeman\nabsorption spectroscopy performed along multiple crystallographic directions\nhas been utilised, in addition to previously determined $g$ tensors for the\n$^{6}$H$_{5/2}$Z$_{1}$ and $^{4}$G$_{5/2}$A$_{1}$ states. The resultant\nanalyses give good approximation to the experimental energy levels and magnetic\nsplittings, yielding crystal-field parameters consistent with the few other\nlanthanide ions for which such analyses are available.",
        "positive": "Hybrid functionals within the all-electron FLAPW method: implementation\n  and applications of PBE0: We present an efficient implementation of the PBE0 hybrid functional within\nthe full-potential linearized augmented-plane-wave (FLAPW) method. The\nHartree-Fock exchange term, which is a central ingredient of hybrid\nfunctionals, gives rise to a computationally expensive nonlocal potential in\nthe one-particle Schroedinger equation. The matrix elements of this exchange\npotential are calculated with the help of an auxiliary basis that is\nconstructed from products of FLAPW basis functions. By representing the Coulomb\ninteraction in this basis the nonlocal exchange term becomes a Brillouin-zone\n(BZ) sum over vector-matrix-vector products. We show that the Coulomb matrix\ncan be made sparse by a suitable unitary transformation of the auxiliary basis,\nwhich accelerates the computation of the vector-matrix-vector products\nconsiderably. Additionally, we exploit spatial and time-reversal symmetry to\nidentify the nonvanishing exchange matrix elements in advance and to restrict\nthe k summations for the nonlocal potential to an irreducible set of k points.\nFavorable convergence of the self-consistent-field cycle is achieved by a\nnested density-only and density-matrix iteration scheme. We discuss the\nconvergence with respect to the parameters of our numerical scheme and show\nresults for a variety of semiconductors and insulators, including oxide\nmaterials, where the PBE0 hybrid functional improves the band gaps and the\ndescription of localized states in comparison with the PBE functional.\nFurthermore, we find that in contrast to conventional local\nexchange-correlation functionals ferromagnetic EuO is correctly predicted to be\na semiconductor."
    },
    {
        "anchor": "Electronic and Transport Properties of Radially Deformed Double-walled\n  Carbon Nanotube Intramolecular Junction: The electronic and transport property of a radially deformed double-walled\ncarbon nanotube (DWNT) intramolecular junction (IMJ) has been studied by the\ntight-binding (TB) model combined with the first-principle calculations. The\ngeometrical structures of the DWNT IMJ have been first optimized in energy by\nthe universal force field (UFF) method. It is found that when heavily squashed,\nthe DWNT will become an insulator-coated metallic wire, and the conductance\nnear the Fermi level has been significantly changed by the radial squash.\nSpecially, several resonance conductance peaks appear at some energies in the\nconduction band of the squashed DWNT IMJ. Finally, we have also investigated\nthe conductance variation due to change of the length of the central\nsemiconductor in the squashed DWNT IMJ. Furthermore, a promising pure carbon\nnanoscale electronic device is proposed based on the DWNT IMJ.",
        "positive": "Influence of limestone filler and of the size of the aggregates on DEF: This experimental study aims to determine the effect of limestone filler on\nconcrete expansion due to delayed ettringite formation (DEF). Different mortars\nmade with different sizes and percentages of limestone filler and Portland\ncement CEM I 52.5N are conserved in water. The expansion of the specimens is\nmeasured. Results show that DEF is not inhibited by limestone filler. The\nkinetics and the amplitude of the swelling depend on the size of the limestone\nfiller. The volume fraction of aggregates changes only the kinetics: the\nrelation between swelling and water uptake depends only on the size of the\naggregates."
    },
    {
        "anchor": "Islands in the Gap: Intertwined Transport and Localization in\n  Structurally Complex Materials: Localized waves in disordered one-dimensional materials have been studied for\ndecades, including white-noise and correlated disorder, as well as\nquasi-periodic disorder. How these wave phenomena relate to those in\ncrystalline (periodic ordered) materials---arguably the better understood\nsetting---has been a mystery ever since Anderson discovered disorder-induced\nlocalization. Nonetheless, together these revolutionized materials science and\ntechnology and led to new physics far beyond the solid state. We introduce a\nbroad family of structurally complex materials---chaotic crystals---that\ninterpolate between these organizational extremes---systematically spanning\nperiodic structures and random disorder. Within the family one can tune the\ndegree of disorder to sweep through an intermediate structurally disordered\nregion between two periodic lattices. This reveals new transport and\nlocalization phenomena reflected in a rich array of energy-dependent\nlocalization degree and density of states. In particular, strong localization\nis observed even with a very low degree of disorder. Moreover, markedly\nenhanced localization and delocalization coexist in a very narrow range of\nenergies. Most notably, beyond the simply smoothed bands found in previous\ndisorder studies, islands of transport emerge in band gaps and sharp band\nboundaries persist in the presence of substantial disorder. Finally, the family\nof materials comes with rather direct specifications of how to assemble the\nrequisite material organizations.",
        "positive": "Weyl semimetals as catalysts: The search for highly efficient and low-cost catalysts is one of the main\ndriving forces in catalytic chemistry. Current strategies for the catalyst\ndesign focus on increasing the number and activity of local catalytic sites,\nsuch as the edge-sites of molybdenum disulfides in the hydrogen evolution\nreaction (HER). Here, we propose and demonstrate a different principle that\ngoes beyond local site optimization by utilizing topological electronic states,\na global property of the material, to spur catalytic activity. For HER, we have\nfound excellent catalysts among the transition-metal monopnictides - NbP, TaP,\nNbAs, and TaAs - which were recently discovered to be topological Weyl\nsemimetals. In addition to the free energy considerations we explore the role\nof metallicity, carrier mobility and topological electronic states for\nremarkable HER performance of these materials. The combination of robust\ntopological surface states and large room temperature carrier mobility both of\nwhich originate from bulk Dirac bands of the Weyl semimetal appears to be the\nrecipe for good HER catalyst. Our work provides a guiding principle for the\ndiscovery of novel catalysts from the emerging field of topological materials."
    },
    {
        "anchor": "Fundamentals and applications of isotope effect in modern technology: In this short review I discuss the effect of isotopic mass and isotopic\ndisorder on the properties (vibrational, elastic, thermal and optical) of\ndifferent crystals.",
        "positive": "A nonlinear hyperelasticity model for single layer blue phosphorus based\n  on ab-initio calculations: A new hyperelastic membrane material model is proposed for single layer blue\nphosphorus ($\\beta\\text{-P}$), also known as blue phosphorene. The model is\nfully nonlinear and captures the anisotropy of $\\beta\\text{-P}$ at large\nstrains. The material model is calibrated from density functional theory (DFT)\ncalculations considering a set of elementary deformation states. Those are pure\ndilatation and uniaxial stretching along the armchair and zigzag directions.\nThe material model is compared and validated with additional DFT results and\nexisting DFT results from the literature, and the comparison shows good\nagreement. The new material model can be directly used within computational\nshell formulations that are for example based on rotation-free isogeometric\nfinite elements. This is demonstrated by simulations of the indentation and\nvibration of single layer blue phosphorus sheets at micrometer scales. The\nelasticity constants at small deformations are also reported."
    },
    {
        "anchor": "Simulation of interstitial diffusion of ion-implanted boron: A model of the interstitial diffusion of ion-implanted boron during rapid\nthermal annealing of silicon layers previously amorphized by implantation of\ngermanium has been proposed. It is supposed that the boron interstitials are\ngenerated continuously during annealing due to dissolution or rearrangement of\nthe clusters of impurity atoms which are formed in the ion-implanted layers\nwith impurity concentration above the solubility limit. The local elastic\nstresses arising due to the difference of boron atomic radius and atomic radius\nof silicon also contribute to the generation of boron interstitials. On the\nbasis of the model proposed a simulation of redistribution of ion-implanted\nboron during rapid thermal annealing with duration of 60 s at a temperature of\n850 degrees Celsius has been carried out. The calculated profile of boron\ndistribution after thermal treatment agrees well with the experimental data\nthat confirms the adequacy of the model. A number of the parameters of\ninterstitial diffusion have been derived. In particular, the average migration\nlength of nonequilibrium boron interstitials is equal to 12 nanometers. It was\nalso obtained that approximately 1.96 % of boron atoms were converted to the\ninterstitial sites, participated in the fast interstitial migration, and then\nbecame immobile again transferring into a substitutional position or forming\nthe electrically inactive complexes with defects of crystal lattice.",
        "positive": "No evidence of isostructural electronic transitions in compressed\n  hydrogen: Ji et al. report performing X-ray diffraction on hydrogen compressed to over\n250 GPa (https://doi.org/10.1038/s41586-019-1565-9). It is a remarkable\ntechnical achievement. However, the experimental data presented and discussed\nin the paper do not support the main conclusion that hydrogen undergoes an\nisostructural phase transition and preserves the hexagonal close packed (hcp)\nstructure up to the highest pressure achieved. The behavior of compressed\nhydrogen in the studied pressure range cannot be explained by electronic\ntopological transition (ETT), as claimed in the paper."
    },
    {
        "anchor": "Electronic structure of fluorides: general trends for ground and excited\n  state properties: The electronic structure of fluorite crystals are studied by means of density\nfunctional theory within the local density approximation for the exchange\ncorrelation energy. The ground-state electronic properties, which have been\ncalculated for the cubic structures $CaF_{2}$,$SrF_{2}$, $BaF_{2}$, $CdF_{2}$,\n$HgF_{2}$, $\\beta $-$PbF_{2}$, using a plane waves expansion of the wave\nfunctions, show good comparison with existing experimental data and previous\ntheoretical results. The electronic density of states at the gap region for all\nthe compounds and their energy-band structure have been calculated and compared\nwith the existing data in the literature. General trends for the ground-state\nparameters, the electronic energy-bands and transition energies for all the\nfluorides considered are given and discussed in details. Moreover, for the\nfirst time results for $HgF_{2}$ have been presented.",
        "positive": "Ag-coverage-dependent symmetry of the electronic states of the\n  Pt(111)-Ag-Bi interface: The ARPES view of a structural transition: We studied by angle-resolved photoelectron spectroscopy the strain-related\nstructural transition from a pseudomorphic monolayer (ML) to a striped\nincommensurate phase in an Ag thin film grown on Pt(111). We exploited the\nsurfactant properties of Bi to grow ordered Pt(111)-xMLAg-Bi trilayers with 0 <\nx < 5 ML, and monitored the dispersion of the Bi-derived interface states to\nprobe the structure of the underlying Ag film. We find that their symmetry\nchanges from threefold to sixfold and back to threefold in the Ag coverage\nrange studied. Together with previous scanning tunneling microscopy and\nphotoelectron diffraction data, these results provide a consistent microscopic\ndescription of the coverage-dependent structural transition."
    },
    {
        "anchor": "Growth of GaAs nanowires on Au, Au / Pd, Ag, Ni, Ga, Cu, Al, Ti metal\n  films: GaAs nanowires were grown by metalorganic vapor phase epitaxy on evaporated\nmetal films (Au, Au / Pd, Ag, Ni, Ga, Cu, Al, Ti). The samples were\ncharacterized by scanning electron microscope (SEM) and transmission electron\nmicroscope (TEM). SEM images reveal that nanowires grow directly on the metals.\nTEM characterization shows crystalline nanowire (nw) structure originating from\nAu. Article presents state of the art about nanowire-metal interface growth and\nenumerates nanowire contacting methods with metals.",
        "positive": "Frequency dependent polarisation switching in h-ErMnO$_3$: We report an electric-field poling study of the geometric-driven improper\nferroelectric h-ErMnO$_3$. From a detailed dielectric analysis we deduce the\ntemperature and frequency dependent range for which single-crystalline\nh-ErMnO$_3$ exhibits purely intrinsic dielectric behaviour, i.e., free from\nextrinsic so-called Maxwell-Wagner polarisations that arise, for example, from\nsurface barrier layers. In this regime ferroelectric hysteresis loops as\nfunction of frequency, temperature and applied electric fields are measured\nrevealing the theoretically predicted saturation polarisation in the order of 5\n- 6 $\\mu$C/cm$^2$. Special emphasis is put on frequency-dependent polarisation\nswitching, which is explained in terms of domain-wall movement similar to\nproper ferroelectrics. Controlling the domain walls via electric fields brings\nus an important step closer to their utilization in domain-wall-based\nelectronics."
    },
    {
        "anchor": "Fe clusters on Ni and Cu: size and shape dependence of the spin moment: We present ab-initio calculations of the electronic structure of small Fe\nclusters (1-9 atoms) on Ni(001), Ni(111), Cu(001) and Cu(111) surfaces.\nEmphasis is given on the spin moments, and their dependence on cluster size and\nshape. We derive a simple quantitative rule, which relates the moment of each\nFe atom linearly to its coordination number. Thus, for an arbitrary Fe cluster\nthe spin moment of the cluster and of the individual Fe atoms can be readily\nfound if the positions of the atoms are known.",
        "positive": "Magnetic susceptibility, exchange interactions and spin-wave spectra in\n  the local spin density approximation: Starting from exact expression for the dynamical spin susceptibility in the\ntime-dependent density functional theory a controversial issue about exchange\ninteraction parameters and spin-wave excitation spectra of itinerant electron\nferromagnets is reconsidered. It is shown that the original expressions for\nexchange integrals based on the magnetic force theorem (J. Phys. F14 L125\n(1984)) are optimal for the calculations of the magnon spectrum whereas static\nresponse function is better described by the ``renormalized'' magnetic force\ntheorem by P. Bruno (Phys. Rev. Lett. 90, 087205 (2003)). This conclusion is\nconfirmed by the {\\it ab initio} calculations for Fe and Ni."
    },
    {
        "anchor": "Efficient and Robust Metallic Nanowire Foams for Deep Submicrometer\n  Particulate Filtration: The on-going COVID-19 pandemic highlights the severe health risks posed by\ndeep submicron sized airborne viruses and particulates in the spread of\ninfectious diseases. There is an urgent need for the development of efficient,\ndurable and reusable filters for this size range. Here we report the\nrealization of efficient particulate filters using nanowire-based low-density\nmetal foams which combine extremely large surface areas with excellent\nmechanical properties. The metal foams exhibit outstanding filtration\nefficiencies (>96.6%) in the PM_{0.3} regime, with potentials for further\nimprovement. Their mechanical stability and light weight, chemical and\nradiation resistance, ease of cleaning and reuse, and recyclability further\nmake such metal foams promising filters for combating COVID-19 and other types\nof airborne particulates.",
        "positive": "\\textit{Ab initio} Studies of Magnetism and Topology in solid Pd-rich\n  a-PdSi Alloys: In 1965 Duwez \\textit{et al.} reported having generated an amorphous, stable\nphase of palladium-silicon in the region 15 to 23 atomic percent (at. \\%)\nsilicon. These pioneering efforts have led to the development of solid\nmaterials that are now known as Bulk Metallic Glasses (BMG). In 2019 we\ndiscovered, computationally, that bulk amorphous Pd becomes magnetic, and so\ndoes porous/amorphous Pd. Puzzled by our results we undertook the study of\nseveral solid binary systems in the Pd-rich zone; in particular, the study of\nthe glassy metallic alloy $a$-Pd$_{100-c}$Si$_{c}$, for $0 \\leq c \\leq 22$,\n($c$ in at. \\%) to see what their topology is, what their electronic properties\nare and to inquire about their magnetism. Here we show that this metallic glass\nis in fact magnetic in the region $0 \\leq c < 15$. Collaterally we present\n$\\alpha$ and $\\beta$ magnetization curves that manifest the net magnetic moment\nobserved. We also discuss the topology and the position of the first few peaks\nof the pair distribution functions, which agrees well with experiment. The BMGs\nproduced experimentally so far are limited in size, but despite this\nlimitation, recent industrial efforts have developed some useful devices that\nmay revolutionize technology."
    },
    {
        "anchor": "Sign-reversed anomalous Nernst effect in the ferromagnetic\n  Weyl-semimetal Fe$_{3-x}$GeTe$_2$: the role of Fe vacancies: Anomalous Nernst effect, as a thermal partner of anomalous Hall effect, is\nparticularly sensitive to the Berry curvature anomaly near the Fermi level, and\nhas been used to probe the topological nature of quantum materials. In this\nwork, we report the observation of both effects in the ferromagnetic\nWeyl-semimetal Fe$_{3-x}$GeTe$_2$ with tunable Fe vacancies. With decreasing Fe\nvacancies, the anomalous Hall conductivity evolves as a function of the\nlongitudinal conductivity from the hopping region to the region where the\nintrinsic Berry curvature contribution dominates. Concomitant evolutions in the\nanomalous Nernst signal and the anomalous off-diagonal thermoelectric\ncoefficient are observed below the Curie temperature, displaying a unique sign\nchange caused by the Fe vacancies. Combining these results with\nfirst-principles calculations, we argue that the Fe-vacancy concentration plays\na unique role in simultaneously tuning the chemical potential and\nferromagnetism, which in turn controls the Berry curvature contribution in this\nfamily of ferromagnetic topological semimetals.",
        "positive": "A critical assessment of models of pair-interactions and screening used\n  in analyzing recent warm-dense matter (WDM) experiments: Ultra-fast laser experiments yield increasingly reliable data on warm-dense\nmatter (WDM), but rely on entrenched simplistic theoretical models. We\nre-analyze two topical experiments, avoiding (i) {\\it ad hoc} core-repulsion\nmodels, (ii) \"Yukawa screening\" models and (iii) electron-ion equilibrium\nassumptions. An accurate, rapid density-functional neutral-pseudoatom model\ncoupled to a hyper-netted-chain (HNC) equation with a bridge term is used to\ncompute structure factors, X-Ray scattering, compressibility, phonons and\nresistivity. Electronic-structure codes are used to confirm the calculations.\nThe Yukawa and core-repulsion models are shown to be misleading."
    },
    {
        "anchor": "Fermi level pinning by defects can explain the large reported carbon 1s\n  binding energy variations in diamond: The quantitative evaluation of the carbon hybridization state by X-ray\nphotoelectron spectroscopy (XPS) has been a surface-analysis problem for the\nlast three decades due to the challenges associated with the unambiguous\nidentification of the characteristic binding energy values for sp$^2$ and\nsp$^3$-bonded carbon. While the sp$^2$ binding energy is well established,\nthere is disagreement for the sp$^3$ value in the literature. Here, we compute\nthe binding energy values for model structures of pure and doped-diamond using\ndensity functional theory. The simulation results indicate that the large\nband-gap of diamond allows defects to pin the Fermi level, which results in\nlarge variations of the C(1s) core electron energies for sp$^3$-bonded carbon,\nin agreement with the broad range of experimental C(1s) binding energy values\nfor sp$^3$ carbon reported in the literature. Fermi level pinning by boron is\ndemonstrated by experimental C(1s) binding energies of highly B-doped\nultrananocrystalline diamond that are in good agreement to simulations.",
        "positive": "Simulation of crack propagation in alumina with ab-initio based\n  polarizable force field: We present an effective atomic interaction potential for crystalline\nalpha-Al2O3 generated by the program potfit. The Wolf direct, pairwise\nsummation method with spherical truncation is used for electrostatic\ninteractions. The polarizability of oxygen atoms is included by use of the\nTangney-Scandolo interatomic force field approach. The potential is optimized\nto reproduce the forces, energies and stresses in relaxed and strained\nconfigurations as well as {0001}, {10-10} and {11-20} surfaces of Al2O3.\nDetails of the force field generation are given, and its validation is\ndemonstrated. We apply the developed potential to investigate crack propagation\nin alpha-Al2O3 single crystals."
    },
    {
        "anchor": "Computational Discovery of Two-Dimensional Rare-Earth Iodides: Promising\n  Ferrovalley Materials for Valleytronics: Two-dimensional Ferrovalley materials with intrinsic valley polarization are\nrare but highly promising for valley-based nonvolatile random access memory and\nvalley filter. Using Kinetically Limited Minimization (KLM), an unconstrained\ncrystal structure prediction algorithm, and prototype sampling based on\nfirst-principles calculations, we have discovered 17 new Ferrovalley materials\n(rare-earth iodides RI$_2$, where R is a rare-earth element belonging to Sc, Y,\nor La-Lu, and I is Iodine). The rare-earth iodides are layered and demonstrate\n2H, 1T, or 1T$_d$ phase as the ground-state in bulk, analogous to transition\nmetal dichalcogenides (TMDCs). The calculated exfoliation energy of monolayers\nis comparable to that of graphene and TMDCs, suggesting possible experimental\nsynthesis. The monolayers in the 2H phase exhibit two-dimensional\nferromagnetism due to unpaired electrons in $d$ and $f$ orbitals. Throughout\nthe rare-earth series, $d$ bands show valley polarization at $K$ and $\\bar{K}$\npoints in the Brillouin zone near the Fermi level. Due to strong magnetic\nexchange interaction and spin-orbit coupling, large intrinsic valley\npolarization in the range of 15-143 meV without external stimuli is observed,\nwhich can be tuned and enhanced by applying a biaxial strain. These valleys can\nselectively be probed and manipulated for information storage and processing,\npotentially offering superior performance beyond conventional electronics and\nspintronics. We further show that the 2H ferromagnetic phase of RI$_2$\nmonolayers possesses non-zero Berry curvature and exhibits the valley Hall\neffect with considerable anomalous Hall conductivity. Our work will incite\nexploratory synthesis of the predicted Ferrovalley materials and their\napplication in valleytronics and beyond.",
        "positive": "Single-Molecule Magnets: Ligand-Induced Core Distortion and Multiple\n  Jahn-Teller Isomerism in [Mn12O12(O2CMe)8(O2PPh2)8(H2O)4]: The Mn12Ac single-molecule magnet has been converted for the first time into\na form that contains non-carboxylate ligands. Reaction of Mn12Ac with\ndiphenylphosphinic acid converts it into the title compound in which eight of\nthe acetate (Ac) groups have been replaced with Ph2PO2 (P) groups. The Mn12AcP\nproduct retains the S=10 ground state and single-molecule magnetism properties\nof Mn12Ac, and displays hysteresis loops containing steps due to quantum\ntunneling of the magnetization. The crystal structures show that Mn12AcP can\nexist in three Jahn-Teller isomeric forms differing in the relative arrangement\nof the Mn(III) Jahn-Teller distortion axes."
    },
    {
        "anchor": "Hexagonal MASnI$_3$ exhibiting strong absorption of ultraviolet photons: MASnI$_3$, an organometallic halide, has great potential in the field of\nlead-free perovskite solar cells. Ultraviolet photons have been shown to\ngenerate deep trapping electronic defects in mesoporous TiO$_2$-based\nperovskite, affecting its performance and stability. In this study, the\nstructure, electronic properties, and optical properties of the cubic,\ntetragonal, and hexagonal phases of MASnI$_3$ were studied using\nfirst-principles calculations. The results indicate that the hexagonal phase of\nMASnI$_3$ possesses a larger indirect band gap and larger carrier effective\nmass along the \\emph{c}-axis compared with the cubic and tetragonal phases.\nThese findings were attributed to the enhanced electronic coupling and\nlocalization in the hexagonal phase. Moreover, the hexagonal phase exhibited\nhigh absorption of ultraviolet photons and high transmission of visible\nphotons, particularly along the \\emph{c}-axis. These characteristics\ndemonstrate the potential of hexagonal MASnI$_3$ for application in\nmultijunction perovskite tandem solar cells or as coatings in mesoporous\nTiO$_2$-based perovskite solar cells to enhance ultraviolet stability and\nphoton utilization.",
        "positive": "Substituent-level Tuning of Frontier Orbital Energy Levels in\n  Phthalocyanine/C60 Donor-Acceptor Charge Transfer Pairs: We have calculated several low-lying Charge Transfer (CT) excited-state\nenergies for four non-covalently bound dyads composed of a sulfonated-ZnPc\ncoupled to C60. Our results show that the di- and tri-sulfonated systems yield\na CT state as the lowest-energy excited state in the system. In contrast, an\nenergy re-ordering for the tetra-sulfonated ZnPc system leads to local\nexcitations lying lower in energy than the CT state, displaying a possible\ndeactivation pathway obstructing charge separation. Since several different\ndonor-acceptor relative orientations may co-exist at an organic heterojunction,\nwe compare the energetics of a few low-lying CT states for the end-on geometry\nof a di-sulfonated system to its co-facial orientation counterpart. The\ncalculated CT excitation energies are larger for the end-on orientation in\ncomparison to the co-facial structure by ~1.5 eV, which results principally\nfrom a substantial decrease in exciton binding energy in going from the\nco-facial to the end-on orientation. Furthermore, changes in relative\ndonor-acceptor orientation have a larger impact on the CT energies than changes\nin donor-acceptor distance. TDDFT calculations on the various sulfonated ZnPc\ndonor molecules show a significant splitting of the Q-band for only one of the\nfour donor systems. Our present calculations, in line with previous\nexperimental studies, show that the systematic variation of chemical functional\ngroups is a promising avenue for the substituent-level tuning of various\nphysical properties of organic semiconductors."
    },
    {
        "anchor": "Low temperature acoustic polaron localization: We calculate the low temperature properties of an acoustic polaron in three\ndimensions in thermal equilibrium at a given temperature using a specialized\npath integral Monte Carlo method. In particular we find numerical evidence that\nthe chosen Hamiltonian for the acoustic polaron describes a phase transition\nfrom a localized state to an unlocalized state for the electron as the\nphonons-electron coupling constant decreases. The phase transition manifests\nitself with a jump discontinuity in the potential energy as a function of the\ncoupling constant. In the weak coupling regime the electron is in an extended\nstate whereas in the strong coupling regime it is found in a self-trapped\nstate.",
        "positive": "Magneto-resistive memory in ferromagnetic (Ga,Mn)As nanostructures: We show a novel magneto-resistive effect that appears in lithographically\nshaped, three-arm nanostructure, fabricated from ferromagnetic (Ga,Mn)As\nlayers. The effect, related to a rearrangement of magnetic domain walls between\ndifferent pairs of arms in the structure, reveals as a dependence of zero-field\nresistance on the direction of previously applied magnetic field. This effect\ncould allow designing devices with unique switching and memory properties."
    },
    {
        "anchor": "Identification of Potential Replacement Materials for Lead in CH3NH3PbI3\n  using First Principle Calculations: There is a need for replacement material for lead due to its toxicity in\norganic-inorganic hybrid halide to facilitate its wide range photovoltaic\napplications. Here, first-principle calculations are used to screen some of the\nelements from the periodic table.",
        "positive": "Anisotropic spin splitting of the electron ground state in InAs quantum\n  dots: Photoinduced circular dichroism experiments in an oblique magnetic field\nallow measurements of Larmor precession frequencies, and so give a precise\ndetermination of the electron Lande g factor and its anisotropy in\nself-assembled InAs/GaAs quantum dots emitting at 1.32 eV. In good agreement\nwith recent theoretical results, we measure g perp= 0.397 +_ 0.003 and g par =\n0.18 +- 0.02."
    },
    {
        "anchor": "Magnetic properties of iron nanoparticles prepared by exploding wire\n  technique: Nanoparticles of iron were prepared in distilled water using very thin iron\nwires and sheets, by the electro-exploding wire technique. Transmission\nelectron microscopy reveals the size of the nanoparticles to be in the range 10\nto 50 nm. However, particles of different sizes can be segregated by using\nultrahigh centrifuge. X-ray diffraction studies confirm the presence of the\ncubic phase of iron. These iron nanoparticles were found to exhibit\nfluorescence in the visible region in contrast to the normal bulk material. The\nroom temperature hysteresis measurements upto a field of 1.0 tesla were\nperformed on a suspension of iron particles in the solution as well as in the\npowders obtained by filtration. The hysteresis loops indicate that the\nparticles are superparamagnetic in nature. The saturation magnetizations was ~\n60 emu / gm. As these iron particles are very sensitive to oxygen a coating of\nnon-magnetic iron oxide tends to form around the particles giving it a core -\nshell structure. The core particle size is estimated theoretically from the\nmagnetization measurements. Suspensions of iron nanoparticles in water have\nbeen proposed to be used as an effective decontaminant for ground water.",
        "positive": "Advances of Machine Learning in Materials Science: Ideas and Techniques: In this big data era, the use of large dataset in conjunction with machine\nlearning (ML) has been increasingly popular in both industry and academia. In\nrecent times, the field of materials science is also undergoing a big data\nrevolution, with large database and repositories appearing everywhere.\nTraditionally, materials science is a trial-and-error field, in both the\ncomputational and experimental departments. With the advent of machine\nlearning-based techniques, there has been a paradigm shift: materials can now\nbe screened quickly using ML models and even generated based on materials with\nsimilar properties; ML has also quietly infiltrated many sub-disciplinary under\nmaterials science. However, ML remains relatively new to the field and is\nexpanding its wing quickly. There are a plethora of readily-available big data\narchitectures and abundance of ML models and software; The call to integrate\nall these elements in a comprehensive research procedure is becoming an\nimportant direction of material science research. In this review, we attempt to\nprovide an introduction and reference of ML to materials scientists, covering\nas much as possible the commonly used methods and applications, and discussing\nthe future possibilities."
    },
    {
        "anchor": "Field dependent neutron diffraction study in Ni50Mn38Sb12 Heusler alloy: In this paper, we present temperature and field dependent neutron diffraction\n(ND) study to unravel the structural and the magnetic properties in\nNi50Mn38Sb12 Heusler system. This alloy shows martensitic transition from high\ntemperature austenite cubic phase to low temperature martensite orthorhombic\nphase on cooling. At 3 K, the lattice parameters and magnetic moments are found\nto be almost insensitive to field. Just below the martensitic transition\ntemperature, the martensite phase fraction is found to be 85%. Upon applying\nthe field, the austenite phase becomes dominant, and the field induced reverse\nmartensitic transition is clearly observed in the ND data. Therefore, the\npresent study gives an estimate of the strength of the martensite phase or the\nsharpness of the martensitic transition. Variation of individual moments and\nthe change in the phase fraction obtained from the analysis of the ND data\nvividly show the change in the magneto-structural state of the material across\nthe transition.",
        "positive": "Negative Poisson's ratio materials via isotropic interactions: We show that under tension, a classical many-body system with only isotropic\npair interactions in a crystalline state can, counterintutively, have a\nnegative Poisson's ratio, or auxetic behavior. We derive the conditions under\nwhich the triangular lattice in two dimensions and lattices with cubic symmetry\nin three dimensions exhibit a negative Poisson's ratio. In the former case, the\nsimple Lennard-Jones potential can give rise to auxetic behavior. In the latter\ncase, negative Poisson's ratio can be exhibited even when the material is\nconstrained to be elastically isotropic."
    },
    {
        "anchor": "Robustness and stability of half-metallic ferromagnetism in\n  alkaline-earth metal mononitrides against doping and deformation: We employ ab-initio electronic structure calculations and study the magnetic\nproperties of CaN and SrN compounds crystallizing in the rocksalt structure.\nThese alkaline-earth metal mononitrides are found to be half-metallic with a\ntotal spin magnetic moment per formula unit of 1.0 $\\mu_B$. The Curie\ntemperature is estimated to be 480 K for CaN and 415 K for SrN well-above the\nroom temperature. Upon small degrees of doping with holes or electrons, the\nrigid-band model suggests that the magnetic properties are little affected.\nFinally we studied for these alloys the effect of deformation taking into\naccount tetragonalization keeping constant the unit cell volume which models\nthe growth on various substrates. Even large degrees of deformation only\nmarginally affect the electronic and magnetic properties of CaN and SrN in the\nrocksalt structure. Finally, we show that this stands also for the zincblende\nstructure. Our results suggest that alkaline-earth metal mononitrides are\npromising materials for magnetoelectronic applications.",
        "positive": "Depth Resolution of Piezoresponse Force Microscopy: Given that a ferroelectric domain is generally a three dimensional entity,\nthe determination of its area as well as its depth is mandatory for full\ncharacterization. Piezoresponse force microscopy (PFM) is known for its ability\nto map the lateral dimensions of ferroelectric domains with high accuracy.\nHowever, no depth profile information has been readily available so far. Here,\nwe have used ferroelectric domains of known depth profile to determine the\ndependence of the PFM response on the depth of the domain, and thus effectively\nthe depth resolution of PFM detection."
    },
    {
        "anchor": "Chlorine and zinc co-doping effects on the electronic structure and\n  optical properties of \u03b3-CuI: The effects of chlorine (Cl) and zinc (Zn) co-doping on the electronic\nstructure and optical properties of the zinc blende ({\\gamma}) phase of copper\niodide ({\\gamma}-CuI) scintillator material are investigated by using\nfirst-principles density functional theory calculations. The band structure,\ndensity of states, dielectric function, absorption coefficients, and\nreflectivity were analyzed before and after doping. Results show co-doping\nsignificantly modifies the band structure, reduces the band gap, and generates\nimpurity energy levels. Cl doping enhances absorption in the high energy region\nwhile reducing visible light absorption. Zn doping induces a redshift in\nabsorption and n-type conductivity at high concentrations. With suitable\nco-doping ratios, the absorption coefficient and reflectivity of {\\gamma}-CuI\ncan be optimized in the visible range to improve scintillation light yield. The\ncalculations provide guidance for co-doping {\\gamma}-CuI scintillators to\nachieve superior detection performance. The n-type conductivity also makes\ndoped {\\gamma}-CuI promising for optoelectronic applications.",
        "positive": "Chirality Induced Propagation Velocity Asymmetry: The spin-dependent propagation of electrons in helical nanowires is\ninvestigated. We show that the interplay of spin angular momentum and nanowire\nchirality, under spin-orbit interaction, lifts the symmetry between left and\nright propagating electrons, giving rise to a velocity asymmetry. The study is\nbased on a microscopic tight-binding model that takes into account the\nspin-orbit interaction. The continuity equation for the spin-dependent\nprobability density is derived, including the spin non-conserving terms, and\nquantum dynamics calculations are performed to obtain the electron propagating\ndynamics. The calculations are applied to the inorganic double-helix SnIP, a\nquasi-1D material that constitutes a semiconductor with a band gap of ~ 1.9 eV.\nThe results, nevertheless, have general validity due to symmetry\nconsiderations. The relation of the propagation velocity asymmetry with the\nphenomena ascribed to the chiral-induced spin selectivity (CISS) effect is\nexamined."
    },
    {
        "anchor": "Altermagnetism in NiSi with non-collinear spins: Recently, a new class of magnetic phenomenon, called altermagnetism, was\nproposed where the underlying spin configuration resembles antiferromagnetic\nstructure, but the system violates \\textbf{PT} (PT: Parity times Time reversal)\nsymmetry due to the alternation of crystalline symmetry across magnetic ions.\nAlthough the original idea was proposed for the collinear spin structure, a\nrecent report by Cheong et al. has suggested that antiferromagnetic materials\nwith non-collinear spin structure and local alternation of crystalline\narrangement can also manifest altermagnetism. Besides breaking the \\textbf{PT}\nsymmetry, altermagnetic compounds are also expected to exhibit anomalous Hall\neffects of odd orders. Here, we discuss possible candidates in this regard. One\nexample is nickel monosilicide, which was recently shown to exhibit high\ntemperature antiferromagnetism with non-collinear spin structure. It fulfills\nboth criteria of breaking the \\textbf{PT} symmetry and linear anomalous Hall\neffect. In addition to NiSi, we also discuss two other potential experimental\nvenues for the exploration of altermagnetic states.",
        "positive": "Growth and Characterization of Bulk Aluminum Nitride by Physical Vapor\n  Transport: A major issue in the development of the technology of nitride based materials\nis the choice of substrate. The structural and optical properties of the layers\nare intimately connected to the substrate material used in the epitaxial\ngrowth. Key issues include lattice matching of substrate and epitaxial layer\nand the difference in the thermal expansion between the substrate and epitaxial\nlayer. Due to the extremely high vapor pressure of nitrogen over Gallium\nNitride (GaN), pure GaN substrate are very difficult to produce and currently\nalmost all nitride-based device are fabricated by hetero-epitaxy on either\nSapphire or Silicon Carbide (SiC). Alternatively, AlN has a significantly lower\nvapor pressure of nitrogen and can be grown in bulk form. In this paper we\nreport on our results in the growth of AlN by physical vapor transport. A\ntheoretical model was developed to investigate the growth process by to\ndetermine optimal growth parameters. Several different seed crystals were\ninvestigated, singular 6H-SiC, 3.50 off-axis 6H-SiC and 80 off-axis 4H-SiC, and\nAlN grown by hydride vapor deposition on silicon substrates (the silicon\nsubstrates were subsequently removed by etching). Auger electron microscopy,\ntransmission electron microscopy, and various X-ray diffraction techniques were\nused to investigate the samples grown."
    },
    {
        "anchor": "Circumventing the Stability Problems of Graphene Nanoribbon Zigzag Edges: Carbon nanostructures with zigzag edges exhibit unique properties with\nexciting potential applications. Such nanostructures are generally synthesized\nunder vacuum because their zigzag edges are unstable under ambient conditions:\na barrier that must be surmounted to achieve their scalable exploitation. Here,\nwe prove the viability of chemical protection/deprotection strategies for this\naim, demonstrated on labile chiral graphene nanoribbons (chGNRs). Upon\nhydrogenation, the chGNRs survive an exposure to air, after which they are\neasily converted back to their original structure via annealing. We also\napproach the problem from another angle by synthesizing a chemically stable\noxidized form of the chGNRs that can be converted to the pristine hydrocarbon\nform via hydrogenation and annealing. These findings may represent an important\nstep toward the integration of zigzag-edged nanostructures in devices.",
        "positive": "Microstructure, grain boundary evolution and anisotropic Fe segregation\n  in (0001) textured Ti thin films: The structure and chemistry of grain boundaries (GBs) are crucial in\ndetermining polycrystalline materials' properties. Faceting and solute\nsegregation to minimize the GB energy is a commonly observed phenomenon. In\nthis paper, a deposition process to obtain pure tilt GBs in titanium (Ti) thin\nfilms is presented. By increasing the power density, a transition from\npolycrystalline film growth to a maze bicrystalline Ti film on SrTiO$_3$ (001)\nsubstrate is triggered. All the GBs in the bicrystalline thin film are\ncharacterized to be $\\Sigma$13 [0001] coincident site lattice (CSL) boundaries.\nThe GB planes are seen to distinctly facet into symmetric {$\\bar{7}520$} and\nasymmetric {$10\\bar{1}0$} // {$11\\bar{2}0$} segments of 20-50~nm length.\nAdditionally, EDS reveals preferential segregation of iron (Fe) in every\nalternate symmetric {$\\bar{7}520$} segment. Both the faceting and the\nsegregation are explained by a difference in the CSL density between the facet\nplanes. Furthermore, in the GB plane containing Fe segregation, atom probe\ntomography is used to experimentally determine the GB excess solute to be\n1.25~atoms/nm$^{2}$. In summary, the study reveals for the first time a\nmethodology to obtain bicrystalline Ti thin films with strong faceting and\nanisotropy in iron (Fe) segregation behaviour within the same family of planes."
    },
    {
        "anchor": "Ex-situ control of fine-structure splitting and excitonic binding\n  energies in single InAs/GaAs quantum dots: A systematic study of the impact of annealing on the electronic properties of\nsingle InAs/GaAs quantum dots (QDs) is presented. We are able to record single\nQD cathodoluminescence spectra and trace the evolution of one and the same QD\nover several steps of annealing. A systematic reduction of the excitonic\nfine-structure splitting is reported. In addition the binding energies of\ndifferent excitonic complexes change dramatically. The results are interpreted\nin terms of a change of electron and hole wavefunction shape and mutual\nposition.",
        "positive": "Zoology of multiple-Q spin textures in a centrosymmetric tetragonal\n  magnet with itinerant electrons: Magnetic skyrmion is a topologically stable particle-like swirling spin\ntexture potentially suitable for high-density information bit, which was first\nobserved in noncentrosymmetric magnets with Dzyaloshinskii-Moriya interaction.\nRecently, nanometric skyrmion has also been discovered in centrosymmetric\nrare-earth compounds, and the identification of their skyrmion formation\nmechanism and further search of nontrivial spin textures are highly demanded.\nHere, we have exhaustively studied magnetic structures in a prototypical\nskyrmion-hosting centrosymmetric tetragonal magnet GdRu2Si2, by performing the\nresonant X-ray scattering experiments. We identified a rich variety of double-Q\nmagnetic structures, including the antiferroic order of\nmeron(half-skyrmion)/anti-meronlike textures with fractional local topological\ncharges. The observed intricate magnetic phase diagram has been successfully\nreproduced by the theoretical framework considering the four-spin interaction\nmediated by itinerant electrons and magnetic anisotropy. The present results\nwill contribute to the better understanding of the novel skyrmion formation\nmechanism in this centrosymmetric rare-earth compound, and suggest that\nitinerant electrons can ubiquitously host a variety of unique multiple-Q spin\norders in a simple crystal lattice system."
    },
    {
        "anchor": "Improved electro-grafting of nitropyrene onto onion-like carbon via in\n  situ electrochemical reduction and polymerization: Tailoring redox energy\n  density of the supercapacitor positive electrode: Herein, we report a improved method for the physical grafting of\n1-nitropyrene (Pyr-NO2) onto highly graphitized carbon onion. This is achieved\nthrough a lowering of the onset potential of the pyrene polymerization via in\nsitu reduction of the NO2 group. The additional redox activity pertaining to\nthe reduced NO2 enables exceeding the faradaic capacity which is associated\nwith the p-doping of the grafted pyrene backbone, as observed for pyrene,\n1-aminopyrene, and unreduced Pyr- NO2. Theoretical calculations demonstrate the\ncharge transfer and binding enthalpy capabilities of Pyr-NO2, which are\nsignificantly higher than those of the other two species, and which allow for\nimproved p-stacking on the carbon surface. Upon 20 wt % grafting of Pyr-NO2,\nthe capacity of the electrode jumps from 20 mAh g-1 electrode to 38 mAh g-\nelectrode, which corresponds to 110 mAh g-1 per mass of Pyr-NO2 and the average\npotential is increased by 200 mV. Very interestingly, this high performance is\nalso coupled with outstanding retention with respect to both the initial\ncapacity for more than 4000 cycles, as well as the power characteristics,\ndemonstrating the considerable advantages of employing the present in situ\ngrafting technique.",
        "positive": "Anisotropic thermo-mechanical response of layered hexagonal boron\n  nitride and black phosphorus: application as a simultaneous pressure and\n  temperature sensor: Hexagonal boron nitride (hBN) and black phosphorus (bP) are crystalline\nmaterials that can be seen as ordered stackings of two-dimensional layers,\nwhich lead to outstanding anisotropic physical properties. The knowledge of the\nthermal equations of state of hBN and bP is of great interest in the field of\n2D materials for a better understanding of the anisotropic thermo-mechanical\nproperties and exfoliation mechanism of these materials. Despite several\ntheoretical and experimental studies, important uncertainties remain in the\ndetermination of the thermoelastic parameters of hBN and bP. Here, we report\naccurate thermal expansion and compressibility measurements along the\nindividual crystallographic axes, using in situ high-temperature and\nhigh-pressure high-resolution synchrotron X-ray diffraction. In particular, we\nhave quantitatively determined the subtle variations of the in-plane\nthermo-mechanical parameters by subjecting these materials to hydrostatic\npressure conditions and collecting a large number of data points in small\npressure and temperature increments. Based on the anisotropic behavior of bP,\nwe propose the use of this material as sensor for the simultaneous\ndetermination of pressure and temperature in the range 0-5 GPa, 298-1700 K."
    },
    {
        "anchor": "Study of the influence of the molecular organization on single-layer\n  OLEDs' performances: The authors synthesized three new silole derivs. with incrementally flexible\nstructure to tune their packing ability and therefore study the influence of\nthe mol. organization in single-layer OLEDs. This architecture was chosen since\nthe absence of org. layers interfaces allows a better evaluation of the role of\nthe mol. arrangement in the active layer. The examn. of the EL properties gives\nevidences of the prominent role of the mol. organization on the OLED\nefficiency. A cryst.-like organization of the mols. allows high c.d. but low\nluminance efficiency since an excessive electron current flow is involved\ncompared to the hole one, and the recombination rate is poor. On the contrary,\ndisordered assemblies of mols. allows better performances by avoiding\nunfavorable p-stacking, while keeping good intermol. orbital overlaps to\nsupport charge carrier transport.",
        "positive": "Renormalization group approach to multiscale modelling in materials\n  science: Dendritic growth, and the formation of material microstructure in general,\nnecessarily involves a wide range of length scales from the atomic up to sample\ndimensions. The phase field approach of Langer, enhanced by optimal asymptotic\nmethods and adaptive mesh refinement, copes with this range of scales, and\nprovides an effective way to move phase boundaries. However, it fails to\npreserve memory of the underlying crystallographic anisotropy, and thus is\nill-suited for problems involving defects or elasticity. The phase field\ncrystal (PFC) equation-- a conserving analogue of the Hohenberg-Swift equation\n--is a phase field equation with periodic solutions that represent the atomic\ndensity. It can natively model elasticity, the formation of solid phases, and\naccurately reproduces the nonequilibrium dynamics of phase transitions in real\nmaterials. However, the PFC models matter at the atomic scale, rendering it\nunsuitable for coping with the range of length scales in problems of serious\ninterest. Here, we show that a computationally-efficient multiscale approach to\nthe PFC can be developed systematically by using the renormalization group or\nequivalent techniques to derive appropriate coarse-grained coupled phase and\namplitude equations, which are suitable for solution by adaptive mesh\nrefinement algorithms."
    },
    {
        "anchor": "The Displacement Field Associated with the Freezing of a Melt and its\n  Role in Determining Crystal Growth Kinetics: The atomic displacements associated with the freezing of metals and salts are\ncalculated by treating crystal growth as an assignment problem through the use\nof an optimal transport algorithm. Converting these displacements into time\nscales based on the dynamics of the bulk liquid, we show that we can predict\nthe activation energy for crystal growth rates, including activation energies\nsignificantly smaller than those for atomic diffusion in the liquid. The\nexception to this success, pure metals that freeze into face centred cubic\ncrystals with little to no activation energy, are discussed. The atomic\ndisplacements generated by the assignment algorithm allows us to quantify the\nkey roles of crystal structure and liquid caging length in determining the\ntemperature dependence of crystal growth kinetics.",
        "positive": "Easily doped p-type, low hole effective mass, transparent oxides: Fulfillment of the promise of transparent electronics has been hindered until\nnow largely by the lack of semiconductors that can be doped p-type in a stable\nway, and that at the same time present high hole mobility and are highly\ntransparent in the visible spectrum. Here, a high-throughput study based on\nfirst-principles methods reveals four oxides, namely X2SeO2, with X = La, Pr,\nNd, and Gd, which are unique in that they exhibit excellent characteristics for\ntransparent electronic device applications-i.e., a direct band gap larger than\n3.1 eV, an average hole effective mass below the electron rest mass, and good\np-type dopability. Furthermore, for La2SeO2 it is explicitly shown that Na\nimpurities substituting La are shallow acceptors in moderate to strong\nanion-rich growth conditions, with low formation energy, and that they will not\nbe compensated by anion vacancies VO or VSe."
    },
    {
        "anchor": "New mechanism of kinetic exchange interaction induced by strong magnetic\n  anisotropy: It is well known that the kinetic exchange interaction between\nsingle-occupied magnetic orbitals (s-s) is always antiferromagnetic, while\nbetween single- and double-occupied orbitals (s-d) is always ferromagnetic and\nmuch weaker. Here we show that the exchange interaction between strongly\nanisotropic doublets of lanthanides, actinides and transition metal ions with\nunquenched orbital momentum contains a new s-d kinetic contribution equal in\nstrength with the s-s one. In non-collinear magnetic systems, this s-d kinetic\nmechanism can cause an overall ferromagnetic exchange interaction which can\nbecome very strong for transition metal ions. These findings are fully\nconfirmed by DFT based analysis of exchange interaction in several Ln$^{3+}$\ncomplexes.",
        "positive": "Band Gap of CsCl Film's as a Function of Lattice Constant: The manuscript reports experimental estimation of Cesium Chloride film's band\ngap and compares it with theoretical simulations. The band gap shows a strong\ndependence on it's lattice constant. Also, it is seen that the point defects\npresent in the films strongly affects it's optical properties."
    },
    {
        "anchor": "Strong magnon softening in tetragonal FeCo compounds: Magnons play an important role in fast precessional magnetization reversal\nprocesses serving as a heat bath for dissipation of the Zeeman energy and thus\nbeing responsible for the relaxation of magnetization. Employing \\emph{ab\ninitio} many-body perturbation theory we studied the magnon spectra of the\ntetragonal FeCo compounds considering three different experimental $c/a$\nratios, $c/a=$1.13, 1.18, and 1.24 corresponding to FeCo grown on Pd, Ir, and\nRh, respectively. We find that for all three cases the short-wave-length\nmagnons are strongly damped and tetragonal distortion gives rise to a\nsignificant magnon softening. The magnon stiffness constant $D$ decreases\nalmost by a factor of two from FeCo/Pd to FeCo/Rh. The combination of soft\nmagnons together with the giant magnetic anisotropy energy suggests FeCo/Rh to\nbe a promising material for perpendicular magnetic recording applications.",
        "positive": "The role of device asymmetries and Schottky barriers on the\n  helicity-dependent photoresponse of 2D phototransistors: Circular photocurrents (CPC), namely circular photogalvanic (CPGE) and photon\ndrag effects, have recently been reported both in monolayer and multilayer\ntransition metal dichalcogenide (TMD) phototransistors. However, the underlying\nphysics for the emergence of these effects are not yet fully understood. In\nparticular, the emergence of CPGE is not compatible with the D3h crystal\nsymmetry of two-dimensional TMDs, and should only be possible if the symmetry\nof the electronic states is reduced by influences such as an external electric\nfield or mechanical strain. Schottky contacts, nearly ubiquitous in TMD-based\ntransistors, can provide the high electric fields causing a symmetry breaking\nin the devices. Here, we investigate the effect of these Schottky contacts on\nthe CPC by characterizing the helicity-dependent photoresponse of monolayer\nMoSe2 devices both with direct metal-MoSe2 Schottky contacts and with h-BN\ntunnel barriers at the contacts. We find that, when Schottky barriers are\npresent in the device, additional contributions to CPC become allowed,\nresulting in emergence of CPC for illumination at normal incidence."
    },
    {
        "anchor": "The vapor controller effect on physical properties of CdTe thin films: This paper reports the optical and structural properties of 400 nm\nnanocrystalline cadmium telluride thin films fabricated using a new vapor\ncontroller system in vacuum. This system is indeed a rotating cylinder placed\nin the material steam path during coating process. The upper cross section of\nthe cylinder has one arc groove allowing the steam to pass through. Three type\nsamples were made under different vapor controlling conditions namely; without\ncontroller system (conventional method), with rotating cylinder, and with upper\ncross section of the cylinder alone which acts as a rotating shutter. The\nprepared samples have been studied by X-ray diffraction (XRD), Field Emission\nScanning Electron Microscopy (FESEM) and UV-Vis Spectroscopy techniques. The\nresults show, not only the structural properties were improved by this\ntechnique but also the band gap of samples were changed.",
        "positive": "Pressure-induced giant enhancement of magnetocaloric effects in\n  MnNiSi-based systems: A remarkable decrease of the structural transition temperature of MnNiSi from\n1200 K to <300 K by chemically alloying it with MnFeGe results in a coupling of\nthe magnetic and structural transitions, leading to a large magnetocaloric\neffect near room temperature. It was found that the magnetostructural\ntransition is highly sensitive to external (hydrostatic) pressure: relatively\nlow hydrostatic pressures (~2.4 kbar) lead to an extraordinary enhancement of\nthe isothermal entropy change from $-$\\Delta $S$ = 44 to 89 J/kg K at ambient\n(atmospheric) and 2.4 kbar applied pressures, respectively, for a field change\nof \\Delta $H$ = 5 T. This giant entropy change is associated with a large\nrelative volume change of about 7% induced by 2.4 kbar applied pressure during\nthe magnetostructural transition. The pressure-enhanced magnetocaloric effects\nare accompanied by a shift in transition temperature, an effect that may be\nexploited to tune the transition to the required working temperature, and\nthereby eliminate the need for a given material to possess a large\nmagnetocaloric effect (i.e., entropy change) over a wide temperature range.\nFurthermore, this material also possesses negligible hysteresis losses."
    },
    {
        "anchor": "Resonant inelastic x-ray scattering study of the electronic structure of\n  Cu$_2$O: A resonant inelastic x-ray scattering study of the electronic structure of\nthe semiconductor cuprous oxide, $\\rm Cu_2O$, is reported. When the incident\nx-ray energy is tuned to the Cu K-absorption edge, large enhancements of the\nspectral features corresponding to the electronic transitions between the\nvalence band and the conduction band are observed. A feature at 6.5 eV can be\nwell described by an interband transition from occupied states of mostly Cu 3d\ncharactor to unoccupied states with mixed 3d, 4s and 2p character. In addition,\nan insulating band gap is observed, and the momentum dependence of the lower\nbound is measured along the $\\Gamma-R$ direction. This is found to be in good\nagreement with the valence band dispersion measured with angle-resolved\nphotoemission spectroscopy.",
        "positive": "Direct Experimental Evidence of Exciton-Phonon Bound States in Carbon\n  Nanotubes: We present direct experimental observation of exciton-phonon bound states in\nthe photoluminescence excitation spectra of isolated single walled carbon\nnanotubes in aqueous suspension. The photoluminescence excitation spectra from\nseveral distinct single-walled carbon nanotubes show the presence of at least\none sideband related to the tangential modes, lying {200 meV} above the main\nabsorption/emission peak. Both the energy position and line shapes of the\nsidebands are in excellent agreement with recent calculations [PRL {\\bf\n94},027402 (2005)] that predict the existence of exciton-phonon bound states, a\nsizable spectral weight transfer to these exciton-phonon complexes and that the\namount of this transfer depends on the specific nanotube structure and\ndiameter. The observation of these novel exciton-phonon complexes is a strong\nindication that the optical properties of carbon nanotubes have an excitonic\nnature and also of the central role played by phonons in describing the\nexcitation and recombination mechanisms in carbon nanotubes."
    },
    {
        "anchor": "Spatially Resolved Electronic Properties of Single-Layer WS$_2$ on\n  Transition Metal Oxides: There is a substantial interest in the heterostructures of semiconducting\ntransition metal dichalcogenides (TMDCs) amongst each other or with arbitrary\nmaterials, through which the control of the chemical, structural, electronic,\nspintronic, and optical properties can lead to a change in device paradigms. A\ncritical need is to understand the interface between TMDCs and insulating\nsubstrates, for example high-$\\kappa$ dielectrics, which can strongly impact\nthe electronic properties such as the optical gap. Here we show that the\nchemical and electronic properties of the single-layer (SL) TMDC, WS$_2$, can\nbe transferred onto high-$\\kappa$ transition metal oxide substrates TiO$_2$ and\nSrTiO$_3$. The resulting samples are much more suitable for measuring their\nelectronic and chemical structures with angle-resolved photoemission than their\nnative-grown SiO$_2$ substrates. We probe the WS$_2$ on the micron scale across\n100-micron flakes, and find that the occupied electronic structure is exactly\nas predicted for freestanding SL WS$_2$ with a strong spin-orbit splitting of\n420~meV and a direct band gap at the valence band maximum. Our results suggest\nthat TMDCs can be combined with arbitrary multi-functional oxides, which may\nintroduce alternative means of controlling the optoelectronic properties of\nsuch materials.",
        "positive": "Structural evolution of CO2 filled pure silica LTA zeolite under\n  high-pressure high-temperature conditions: The crystal structure of CO2 filled pure SiO2 LTA zeolite has been studied at\nhigh pressures and temperatures using synchrotron based x ray powder\ndiffraction. Its structure consists of 13 CO2 guest molecules, 12 of them\naccommodated in the large alpha cages and 1 in the beta cages, giving a\nSiO2:CO2 stoichiometric ratio smaller than 2. The structure remains stable\nunder pressure up to 20 GPa with a slight pressure dependent rhombohedral\ndistortion, indicating that pressure induced amorphization is prevented by the\ninsertion of guest species in this open framework. The ambient-temperature\nlattice compressibility has been determined. In situ high pressure resistive\nheating experiments up to 750 K allow us to estimate the thermal expansivity at\n5 GPa. Our data confirm that the insertion of CO2 reverses the negative thermal\nexpansion of the empty zeolite structure. No evidence of any chemical reaction\nwas observed. The possibility of synthesizing a silicon carbonate at high\ntemperatures and higher pressures is discussed in terms of the evolution of C-O\nand Si-O distances between molecular and framework atoms."
    },
    {
        "anchor": "Electronic structure and phase transition in polar ScFeO3 from First\n  Principles Calculations: The properties of newly discovered polar ScFeO3 with magnetic ordering are\nexamined using Ab initio calculations and symmetry mode analysis. The GGA+U\ncalculation confirms the stability of polar R3c Phase in ScFeO3 and the\npressure induced phase transition to non-polar Pnma phase. Octahedron tilting\nand structural properties as a function of applied pressure have been analyzed.\nThe origin of polar phase is associated with instability of non-polar R-3c\nphase and group theory using the symmetry mode analysis has been applied to\nunderstand this instability as well as the spontaneous polarization of polar\nR3c phase. The magnetic phase transition shows G-type AFM ordering of Fe3+ ion\nwithin Goodenough-Kanamori theory and the possibility of magnetic spin\nstructure has been analyzed by using energy analysis including spin canting\npossibility.",
        "positive": "Drastic changes in electronic, magnetic, mechanical and bonding\n  properties from Zr2CoH5 to Mg2CoH5: Despite similarities in formulae and local structures of Zr2CoH5 and Mg2CoH5,\nthey are shown from ab initio calculations to present contrasted electronic,\nmagnetic, mechanical and bonding properties due to the environment of cobalt\nwith hydrogen characterized by negatively charged CoHx entities (x = 4, 5\nresp.) and to the chemical nature of Zr versus Mg. Zr2CoH5 is found more\ncohesive, harder and less ductile than Mg2CoH5. High density of states at the\nFermi level arises from out-of-plane non-bonding Co-dz2 in Zr2CoH5 which is\nfound metallic ferromagnet in the ground state, in contrast with non magnetic\nand insulating Mg2CoH5."
    },
    {
        "anchor": "Optical control of magnetism in NiFe/VO2 heterostructures: Optical methods for magnetism manipulation have been considered as a\npromising strategy for ultralow-power and ultrahigh-speed spin switches, which\nbecomes a hot spot in the field of spintronics. However, a widely applicable\nand efficient method to combine optical operation with magnetic modulation is\nstill highly desired. Here, the strongly correlated electron material VO2 is\nintroduced to realize phase-transition based optical control of the magnetism\nin NiFe. The NiFe/VO2 bilayer heterostructure features appreciable modulations\nin electrical conductivity (55%), coercivity (60%), and magnetic anisotropy\n(33.5%). Further analyses indicate that interfacial strain coupling plays a\ncrucial role in this modulation. Utilizing this optically controlled magnetism\nmodulation feature, programmable Boolean logic gates (AND, OR, NAND, NOR, XOR,\nNXOR and NOT) for high-speed and low-power data processing are demonstrated\nbased on this engineered heterostructure. As a demonstration of\nphase-transition spintronics, this work may pave the way for next-generation\nelectronics in the post-Moore era.",
        "positive": "Varying Cu-Ti hybridization near the Fermi energy in Cu$_{x}$TiSe$_{2}$:\n  Results from supercell calculations: The properties of Cu$_{x}$TiSe$_{2}$ are studied by band structure\ncalculation based on the density functional theory for supercells. The\ndensity-of-states (DOS) for $x$=0 has a sharply raising shoulder in the\nneighborhood of the Fermi energy, $E_F$, which can be favorable for spacial\ncharge modulations. The Cu impurity adds electrons and brings the DOS shoulder\nbelow $E_F$. Hybridization makes the Ti-d DOS at $E_F$, the electron-phonon\ncoupling and the Stoner factor very large. Strong pressure dependent properties\nare predicted from the calculations, since the DOS shoulder is pushed to higher\nenergy at a reduced lattice constant. Effects of disorder are also expected to\nbe important because of the rapidly varying DOS near $E_F$."
    },
    {
        "anchor": "Epitaxial Thin Films of a Chalcogenide Perovskite: Chalcogenide perovskites have emerged as a new class of electronic materials,\nbut fundamental properties and applications of chalcogenide perovskites remain\nlimited by the lack of high quality epitaxial thin films. We report epitaxial\nthin film growth of BaZrS3, a prototypical chalcogenide, by pulsed laser\ndeposition. X-ray diffraction studies show that the films are strongly textured\nout of plane and have a clear in-plane epitaxial relationship with the\nsubstrate. Electron microscopy studies confirm the presence of epitaxy for the\nfirst few layers of the film at the interface, even though away from the\ninterface the films are polycrystalline with a large number of extended defects\nsuggesting the potential for further improvement in growth. X-Ray reflectivity\nand atomic force microscopy show smooth film surfaces and interfaces between\nthe substrate and the film. The films show strong light absorption near the\nband edge and photoluminescence in the visible region. The photodetector\ndevices show fast and efficient photo response with the highest ON/OFF ratio\nreported for BaZrS3 films thus far. Our study opens up opportunities to realize\nepitaxial thin films, heterostructures, and superlattices of chalcogenide\nperovskites to probe fundamental physical phenomena and the resultant\nelectronic and photonic device technologies.",
        "positive": "Random lasing in an organic light-emitting crystal and its interplay\n  with vertical cavity feedback: The simultaneous vertical-cavity and random lasing emission properties of a\nblue-emitting molecular crystal are investigated. The\n1,1,4,4-tetraphenyl-1,3-butadiene samples, grown by physical vapour transport,\nfeature room-temperature stimulated emission peaked at about 430 nm.\nFabry-P\\'erot and random resonances are primed by the interfaces of the crystal\nwith external media and by defect scatterers, respectively. The analysis of the\nresulting lasing spectra evidences the existence of narrow peaks due to both\nthe built-in vertical Fabry-P\\'erot cavity and random lasing in a novel,\nsurface-emitting configuration and threshold around 500 microJ cm^-2. The\nanti-correlation between different modes is also highlighted, due to\ncompetition for gain. Molecular crystals with optical gain candidate as\npromising photonic media inherently supporting multiple lasing mechanisms."
    },
    {
        "anchor": "Edge Saturation effects on the magnetism and band gaps in multilayer\n  graphene ribbons and flakes: Using a density functional theory based electronic structure method and\nsemi-local density approximation, we study the interplay of geometric\nconfinement, magnetism and external electric fields on the electronic structure\nand the resulting band gaps of multilayer graphene ribbons whose edges are\nsaturated with molecular hydrogen (H$_2$) or hydroxyl (OH) groups. We discuss\nthe similarities and differences of computed features in comparison with the\natomic hydrogen (or H-) saturated ribbons and flakes. For H$_2$\nedge-saturation, we find \\emph{shifted} labeling of three armchair ribbon\nclasses and magnetic to non-magnetic transition in narrow zigzag ribbons whose\ncritical width changes with the number of layers. Other computed\ncharacteristics, such as the existence of a critical gap and external electric\nfield behavior, layer dependent electronic structure, stacking-dependent band\ngap induction and the length confinement effects remain qualitatively same with\nthose of H-saturated ribbons.",
        "positive": "A Dynamic Multiscale Phase-field Model for Structural Transformations\n  and Twinning: Regularized Interfaces with Transparent Prescription of Complex\n  Kinetics and Nucleation: The motion of microstructural interfaces is important in modeling materials\nthat undergo twinning and structural phase transformations. Continuum models\nfall into two classes: sharp-interface models, where interfaces are singular\nsurfaces; and regularized-interface models, such as phase-field models, where\ninterfaces are smeared out. The former are challenging for numerical solutions\nbecause the interfaces need to be explicitly tracked, but have the advantage\nthat the kinetics of existing interfaces and the nucleation of new interfaces\ncan be transparently and precisely prescribed. In contrast, phase-field models\ndo not require explicit tracking of interfaces, thereby enabling relatively\nsimple numerical calculations, but the specification of kinetics and nucleation\nis both restrictive and extremely opaque. This prevents straightforward\ncalibration of phase-field models to experiment and/or molecular simulations,\nand breaks the multiscale hierarchy of passing information from atomic to\ncontinuum.\n  We present the formulation of a phase-field model -- i.e., a model with\nregularized interfaces that do not require explicit numerical tracking -- that\nallows for easy and transparent prescription of complex interface kinetics and\nnucleation. The key ingredients are a re-parametrization of the energy density\nto clearly separate nucleation from kinetics; and an evolution law that comes\nfrom a conservation statement for interfaces. This enables clear prescription\nof nucleation through the source term of the conservation law and of kinetics\nthrough an interfacial velocity field. A formal limit of the kinetic driving\nforce recovers the classical continuum sharp-interface driving force, providing\nconfidence in both the re-parametrized energy and the evolution statement.\n  We present a number of numerical calculations in one and two dimensions to\ncharacterize and demonstrate the formulation."
    },
    {
        "anchor": "XAS study of the local environment of impurities in doped TiO2 thin\n  films: In this work we present an X-ray Absorption Spectroscopy characterization of\nthe local environment of the impurity in room temperature ferromagnetic anatase\nTiO2 thin films doped with Co, Ni, Cu, or Zn, deposited on LaAlO3 substrate by\nPulsed Laser Deposition. It was found that there is a considerable amount of\nimpurity atoms substituting Ti in TiO2 anatase, although the presence of metal\ntransition monoxide clusters can not be discarded. From our results we infer\nthat the observed room temperature ferromagnetism of the samples could be\nassigned to the metal transition atoms replacing Ti in TiO2 anatase.",
        "positive": "Nd:YAG laser induced E' centers probed by in situ absorption\n  measurements: We investigated various types of commercial silica irradiated with a pulsed\nNd:YAG laser radiation (4.66 eV), with exposure time ranging up to 10000 s.\nTransient E' centers were probed in situ by measuring the amplitude of the\noptical absorption band at 5.8 eV (due to E' centers) both during and after\nirradiation. The laser-induced absorption is observed only in natural samples,\nwhereas the synthetic materials exhibit high toughness to radiation effect. The\nreported results evidence that the kinetics of E' centers is influenced by\ntheir reaction with diffusing molecular hydrogen H2 made available by\ndimerization of radiolytic H0."
    },
    {
        "anchor": "Regenerative Soot-I: Carbon cluster formation in regenerative sooting\n  plasmas: Laboratory formation of large carbon clusters with m C atoms where m could be\nup to few thousand, in carbonaceous plasma, has been studied by using an\nespecially designed ion source. Carbon is introduced into the glow discharge\nplasma by sputtering of the graphite electrode. Soot dominated plasma is\ncreated whose constituents are carbon clusters. It produces and recycles\ncluster containing plasma. Regenerative sooting plasma creates the environment\nin which the entire spectrum of clusters that contain the linear chains, rings\nand fullerenes. Velocity spectra of the extracted clusters have been measured\nwith an ExB filter. These spectra indicate and identify the mechanisms\noperating in the soot.",
        "positive": "Can the electronic energy spectra of bulk excitonic states be traced to\n  parent molecular states in fluorene and its hetero-analogues? It depends on\n  the mutual orientation of the respective transition dipoles in the crystal: The effect of intermolecular interactions on intensity redistribution between\nindividual electronic transitions in different polymorphs of fluorene and\ndibenzofuran was studied by transmittance electronic spectroscopy in the energy\nrange from onset of absorption to the ionization energy (from ~4.0 eV to ~9.0\neV - Electronic transitions with transition dipoles at oblique angles to the\ncrystallographic axes (A1 symmetry) in these crystals resemble molecular\nspectra. Transitions of B2 symmetry, which in these crystals have parallel\ntransition dipoles, resemble molecular spectra for surface (substrate\ninfluenced) states. For bulk excitonic states the spectra of these transitions\nhave a continuous, uniform intensity distribution in the whole energy range\ninvestigated, except for the case when the B2 transition is the onset of\nabsorption."
    },
    {
        "anchor": "Theoretical study on the electric field effect on magnetism of Pd/Co/Pt\n  thin films: Based on first principles calculations we investigate the electronic and\nmagnetic properties of Pt layers in Pd$(001)$/Co/Pt thin film structures\nexposed to an external electric field. Due to the Co underlayer, the surface Pt\nlayers have induced moments that are modified by an external electric field.\nThe field induced changes can be explained by the modified spin-dependent\norbital hybridization that varies non-linearly with the field strength. We\ncalculate the x-ray absorption and the x-ray magnetic circular dichroism\nspectra for an applied external electric field and examine its impact on the\nspectra in the Pt layer around the L$_{2}$ and L$_{3}$ edges. We also determine\nthe layer dependent magneto-crystalline anisotropy and show that the anisotropy\ncan be tuned easily in the different layers by the external electric field.",
        "positive": "Phase transition kinetics revealed by in situ X-ray diffraction in\n  laser-heated dynamic diamond anvil cells: We report on a novel approach to dynamic compression of materials that\nbridges the gap between previous static- and dynamic- compression techniques,\nallowing to explore a wide range of pathways in the pressure-temperature space.\nBy combining a dynamic-diamond anvil cell setup with double-sided laser-heating\nand in situ X-ray diffraction, we are able to perform dynamic compression at\nhigh temperature and characterize structural transitions with unprecedented\ntime resolution. Using this method, we investigate the $\\gamma-\\epsilon$ phase\ntransition of iron under dynamic compression for the first time, reaching\ncompression rates of hundreds of GPa/s and temperatures of 2000 K. Our results\ndemonstrate a distinct response of the $\\gamma-\\epsilon$ and $\\alpha-\\epsilon$\ntransitions to the high compression rates achieved. These findings open up new\navenues to study tailored dynamic compression pathways in the\npressure-temperature space and highlight the potential of this platform to\ncapture kinetic effects in a diamond anvil cell."
    },
    {
        "anchor": "Influence of substrate on structural and transport properties of LaNiO3\n  thin films prepared by pulsed laser deposition: We report the structural and transport properties of LaNiO3 thin films\nprepared by pulsed laser deposition technique. To understand the effects of\nfilm thickness, lattice mismatch and grain size on transport properties,\nvarious oriented substrates were used for deposition, including\nsingle-crystalline SrLaAlO4 (001), SrTiO3 (100) and LaAlO3 (100). To achieve a\nhigh quality LaNiO3 thin films, the vital parameters (such as laser fluence,\nsubstrate temperature, oxygen pressure, and deposition time) were optimized.\nThe best quality films are found to be well textured samples with good\ncrystalline properties.",
        "positive": "Photosensitive free-standing ultra-thin carbyne-gold films: In the article we introduce the experiment of the photostimulation effect in\nthe tunneling conductivity of free-standing thin C-Au films. We observe a sharp\nincrease of the conductivity of hybrid film due to the electromagnetic exciting\nat the frequencies which are close to the plasmon resonance of gold\nnanoparticles. The use of carbyne threads as a stabilizing matrix makes it\npossible to obtain free-standing thin films that demonstrate a good structural\nstability. The tunnel current-voltage measurements demonstrate a strong\ndependence of the current value on the intensity of green laser radiation used\nto photostimulate thin C-Au in area of the measuring experiment."
    },
    {
        "anchor": "Adsorption of silicon on Au(110): an ordered two dimensional surface\n  alloy: We report on experimental evidence for the formation of a two dimensional\nSi/Au(110) surface alloy. In this study, we have used a combination of scanning\ntunneling microscopy, low energy electron diffraction, Auger electron\nspectroscopy and ab initio calculations based on density functional theory. A\nhighly ordered and stable Si-Au surface alloy is observed subsequent to growth\nof a sub-monolayer of silicon on an Au(110) substrate kept above the eutectic\ntemperature.",
        "positive": "Halide perovskites under polarized light: Vibrational symmetry analysis\n  using polarized Raman: In the last decade, hybrid organic-inorganic halide perovskites have emerged\nas a new type of semiconductor for photovoltaics and other optoelectronic\napplications. Unlike standard, tetrahedrally bonded semiconductors (e.g. Si and\nGaAs), the ionic thermal fluctuations in the halide perovskites (i.e.\nstructural dynamics) are strongly coupled to the electronic dynamics.\nTherefore, it is crucial to obtain accurate and detailed knowledge about the\nnature of atomic motions within the crystal. This has proved to be challenging\ndue to low thermal stability and the complex, temperature dependent structural\nphase sequence of the halide perovskites. Here, these challenges are overcome\nand a detailed analysis of the mode symmetries is provided in the\nlow-temperature orthorhombic phase of methylammonium-lead iodide. Raman\nmeasurements using linearly- and circularly- polarized light at 1.16 eV\nexcitation are combined with density functional perturbation theory (DFPT). By\nperforming an iterative analysis of Raman polarization-orientation dependence\nand DFPT mode analysis, the crystal orientation is determined. Subsequently,\naccounting for birefringence effects detected using circularly polarized light\nexcitation, the symmetries of all the observed Raman-active modes at 10 K are\nassigned."
    },
    {
        "anchor": "A proposed new route to d0 magnetism in semiconductors: Here we propose to induce magnetism in semiconductor utilizing the unique\nproperties of the interstitial defect to act as the magnetic impurity within\nthe alpha-PbO crystal structure. The Pbi interstitial generates the p-localized\nstate with two on-site electrons to obey the Hund's rule for their ordering. It\nis demonstrated that instead of Pb interstitial other non-magnetic impurities\nof s^2p^{x} outer shell configuration can be applied to induce d0 magnetism\nwith possibility to tune the local magnetic moments mu_B by varying a number of\nelectrons 1< x< 3. The magnetic coupling between such defects is found to be\ndriven by the long-range order interactions that in combination with high\ndefect solubility promises the magnetic percolation to remain above the room\ntemperature.",
        "positive": "Distinct magnetic gaps between antiferromagnetic and ferromagnetic\n  orders driven by surface defects in the topological magnet MnBi2Te4: The magnetic topological insulator, MnBi$_2$Te$_4$, shows metallic behavior\nat zero magnetic fields (antiferromagnetic phase, AFM) in thin film transport,\nwhich coincides with gapless surface states observed by angle-resolved\nphotoemission spectroscopy, while it can become a Chern insulator at field\nlarger than 6 T (ferromagnetic phase, FM). Thus, the zero-field surface\nmagnetism was once speculated to be different from the bulk AFM phase. However,\nrecent magnetic force microscopy refutes this assumption by detecting\npersistent AFM order on the surface. In this work, we propose a mechanism\nrelated to surface defects that can rationalize these contradicting\nobservations in different experiments. We find that co-antisites (exchanging Mn\nand Bi atoms in the surface van der Waals layer) can strongly suppress the\nmagnetic gap down to several meV in the AFM phase without violating the\nmagnetic order but preserve the magnetic gap in the FM phase. The different gap\nsizes between AFM and FM phases are caused by the defect-induced surface charge\nredistribution among top two van der Waals layers. This theory can be validated\nby the position- and field-dependent gap in future surface spectroscopy\nmeasurements. Our work suggests suppressing related defects in samples to\nrealize the quantum anomalous Hall insulator or axion insulator at zero fields."
    },
    {
        "anchor": "Growth, Morphology and Stability of Au in Contact with the Bi2Se3(0001)\n  Surface: We report a combined microscopy and spectroscopy study of Au deposited on the\nBi2Se3(0001) single crystal surface. At room temperature Au forms islands,\naccording to the Volmer-Weber growth mode. Upon annealing to 100{\\deg} C the Au\ndeposits are not stable and assemble into larger and thicker islands. The\ntopological surface state of Bi2Se3 is weakly affected by the presence of Au.\nContrary to other metals, such as Ag or Cr, a strong chemical instability at\nthe Au/Bi2Se3 interface is ruled out. Core level analysis highlights Bi\ndiffusion toward the surface of Au islands, in agreement with previous\nfindings, while chemical interaction between Au and atomic Se is limited at the\ninterfacial region. For the investigated range of Au coverages, the Au/Bi2Se3\nheterostructure is inert towards CO and CO2 exposure at low pressure (10-8\nmbar) regime.",
        "positive": "Towards room-temperature single-layer graphene synthesis by C60\n  Supersonic Molecular Beam Epitaxy: High-kinetic energy impacts between inorganic surfaces and molecular beams\nseeded by organics represent a fundamental case study in materials science,\nmost notably when they activate chemical-physical processes leading to\nnanocrystals growth. Here we demonstrate single-layer graphene synthesis on\ncopper by C60 supersonic molecular beam (SuMBE) epitaxy at 645 {\\deg}C, with\nthe possibility of further reduction. Using a variety of electron spectroscopy\nand microscopy techniques, and first-principles simulations, we describe the\nchemical-physical mechanisms activated by SuMBE resulting in graphene growth.\nIn particular, we find a crucial role of high-kinetic energy deposition in\nenhancing the organic/inorganic interface interaction, to control the cage\nopenings and to improve the growing film quality. These results, while\ndiscussed in the specific case of graphene on copper, are potentially\nextendable to different metallic or semiconductor substrates and where lower\nprocessing temperature is desirable."
    },
    {
        "anchor": "Dielectric and Magnetic Properties of (Bi1-xLaxFeO3)0.5(PbTiO3)0.5\n  Ceramics Prepared from Mechanically Synthesized Powders: Multiferroic (Bi1-xLaxFeO3)0.5(PbTiO3)0.5 ceramics was prepared from\nmechanical synthesized nanopowders. The XRD studies revealed the tetragonal\nstructure and the tetragonality decreased with La content. Dielectric response\nof the compounds was found to contain three anomalies: 1) relaxor-like behavior\ndue to lattice disorder (below 300 K); 2) dielectric permittivity maxima at~400\nK attributed to the presence of oxygen vacancies; 3) grain boundary effect\nabove 475 K. The Curie point at ~500 K was observed for the compound with\nx=0.5. The composition near the morphotropic boundary:\n(Bi0.8La0.2FeO3)0.5(PbTiO3)0.5 shoved the highest remnant magnetization. The\nirreversible magnetic properties of the (Bi1-xLaxFeO3)0.5(PbTiO3)0.5 compounds\ncan be explained in terms of disorder induced spin-glass behavior due to random\nsubstitution of La or Pb ions for Bi sites. A sharp step in magnetization about\n250 K is caused by the A-site distortion associated with tilts of FeO6\noctahedra leading to modification of Fe-O-Fe angles and of antiferromagnetic\ncoupling between magnetic Fe3+ moments.",
        "positive": "Anomalous spin-waves and the commensurate-incommensurate magnetic phase\n  transition in LiNiPO4: Detailed spin-wave spectra of magneto-electric LiNiPO4 have been measured by\nneutron scattering at low temperatures in the commensurate (C)\nantiferromagnetic (AF) phase with ordering temperature 20.8 K. An anomalous\nlow-energy mode is observed at the modulation vector of the incommensurate (IC)\nAF phase appearing above the 20.8 K. A linear spin-wave model based on\nHeisenberg exchange couplings and single ion anisotropies accounts for all the\nobserved spin-wave dispersions and intensities. Along the b axis an unusually\nstrong next-nearest-neighbor AF coupling competes with the dominant\nnearest-neighbor AF exchange interaction and causes the IC structure."
    },
    {
        "anchor": "The Sigma 13 (10-14) twin in alpha-Al2O3: A model for a general grain\n  boundary: The atomistic structure and energetics of the Sigma 13 (10-14)[1-210]\nsymmetrical tilt grain boundary in alpha-Al2O3 are studied by first-principles\ncalculations based on the local-density-functional theory with a mixed-basis\npseudopotential method. Three configurations, stable with respect to\nintergranular cleavage, are identified: one Al-terminated glide-mirror twin\nboundary, and two O-terminated twin boundaries, with glide-mirror and two-fold\nscrew-rotation symmetries, respectively. Their relative energetics as a\nfunction of axial grain separation are described, and the local electronic\nstructure and bonding are analysed. The Al-terminated variant is predicted to\nbe the most stable one, confirming previous empirical calculations, but in\ncontrast with high-resolution transmission electron microscopy observations on\nhigh-purity diffusion-bonded bicrystals, which resulted in an O-terminated\nstructure.\n  An explanation of this discrepancy is proposed, based on the different\nrelative energetics of the internal interfaces with respect to the free\nsurfaces.",
        "positive": "Negative Magnetoresistance in Weyl semimetals NbAs and NbP: Intrinsic\n  Chiral Anomaly and Extrinsic Effects: Chiral anomaly induced negative magnetoresistance (NMR) has been widely used\nas a critical transport evidence on the existence of Weyl fermions in\ntopological semimetals. In this mini review, we discuss the general observation\nof the NMR phenomena in non-centrosymmetric NbP and NbAs. We show that NMR can\nbe contributed by intrinsic chiral anomaly of Weyl fermions and/or extrinsic\neffects, such as superimposition of Hall signals, field-dependent inhomogeneous\ncurrent flow in the bulk, i.e. current jetting, and weak localization (WL) of\ncoexistent trivial carriers. Such WL controlled NMR is heavily dependent on\nsample quality, and is characterized by pronounced crossover from positive to\nnegative MR growth at elevated temperatures, as a result of the competition\nbetween the phase coherence time and the spin-orbital scattering constant of\nthe bulk trivial pockets. Thus, the correlation of NMR and chiral anomaly needs\nto be scrutinized, without the support of other complimentary techniques. Due\nto the lifting of spin degeneracy, the spin orientations of Weyl fermions are\neither parallel or antiparallel to the momentum, a unique physical property\nknown as helicity. The conservation of helicity provides strong protection for\nthe transport of Weyl fermions, which can only be effectively scattered by\nmagnetic impurities. Chemical doping of magnetic and non-magnetic impurities\nare thus more convincing in probing the existence of Weyl fermions than the NMR\nmethod."
    },
    {
        "anchor": "Proposal for valleytronic materials: ferrovalley metal and valley\n  gapless semiconductor: Valleytronic materials can provide new degrees of freedom to future\nelectronic devices. In this work, the concepts of the ferrovalley metal (FVM)\nand valley gapless semiconductor (VGS) are proposed, which can be achieved in\nvalleytronic bilayer systems by electric-field tuning, where the interaction\nbetween out-of-plane ferroelectricity and A-type antiferromagnetism can induce\nlayer-polarized anomalous valley Hall (LP-AVH) effect. The K and -K valleys of\nFVM are both metallic, and electron and hole carriers simultaneously exist. In\nthe extreme case, the FVM can become VGS by analogizing spin gapless\nsemiconductor (SGS). Moreover, it is proposed that the valley splitting\nenhancement and valley polarization reversal can be achieved by electric field\nin valleytronic bilayer systems. Taking the bilayer $\\mathrm{RuBr_2}$ as an\nexample, our proposal is confirmed by the first-principle calculations. The FVM\nand VGS can be achieved in bilayer $\\mathrm{RuBr_2}$ by applying electric\nfield. With appropriate electric field range, increasing electric field can\nenhance valley splitting, and the valley polarization can be reversed by\nflipping electric field direction. To effectively tune valley properties by\nelectric field in bilayer systems, the parent monolayer should possess\nout-of-plane magnetization, and have large valley splitting. Our results shed\nlight on the possible role of electric field in tuning valleytronic bilayer\nsystems, and provide a way to design the ferrovalley-related material by\nelectric field.",
        "positive": "Tunnel current in self-assembled monolayers of\n  3-mercaptopropyltrimethoxysilane: The current density-voltage (J-V) characteristics of self assembled\nmonolayers of 3-mercaptopropyltrimethoxysilane (MPTMS) chemisorbed on the\nnative oxide surface of p+-doped Si demonstrate the excellent tunnel dielectric\nbehavior of organic monolayers down to 3 carbon atoms. The J-V characteristics\nof MPTMS SAMs on Si are found to be asymmetric, and the direction of\nrectification has been found to depend upon the applied voltage range. At\nvoltages < 2.45V, the reverse bias current was found to be higher than forward\nbias current; while at higher voltages this trend was reversed. This result is\nin agreement with Simmons theory. The tunnel barrier heights for this short\nchain (2.56 and 2.14 eV respectively at Au and Si interfaces) are in good\nagreement with the ones for longer chains (>10 carbon atoms) if the chain is\nchemisorbed at the electrodes. These results extend all previous experiments on\nsuch molecular tunnel dielectrics down to 3 carbon atoms. This suggests that\nthese molecular monolayers, having good tunnel behavior (up to 2.5 eV) over a\nlarge bias range, can be used as gate dielectric well below the limits of\nSi-based dielectrics."
    },
    {
        "anchor": "Identification of excitonic phonon sideband by photoluminescence\n  spectroscopy of single-walled carbon-13 nanotubes: We have studied photoluminescence (PL) and resonant Raman scatterings of\nsingle-walled carbon nanotubes (SWNTs) consisting of carbon-13 (SW13CNTs)\nsynthesized from a small amount of isotopically modified ethanol. There was\nalmost no change in the Raman spectra shape for SW13CNTs except for a downshift\nof the Raman shift frequency by the square-root of the mass ratio 12/13. By\ncomparing photoluminescence excitation (PLE) spectra of SW13CNTs and normal\nSWNTs, the excitonic phonon sideband due to strong exciton-phonon interaction\nwas clearly identified with the expected isotope shift.",
        "positive": "Polarizing an antiferromagnet by optical engineering of the crystal\n  field: Strain engineering is widely used to manipulate the electronic and magnetic\nproperties of complex materials. An attractive route to control magnetism with\nstrain is provided by the piezomagnetic effect, whereby the staggered spin\nstructure of an antiferromagnet is decompensated by breaking the crystal field\nsymmetry, which induces a ferrimagnetic polarization. Piezomagnetism is\nespecially attractive because unlike magnetostriction it couples strain and\nmagnetization at linear order, and allows for bi-directional control suitable\nfor memory and spintronics applications. However, its use in functional devices\nhas so far been hindered by the slow speed and large uniaxial strains required.\nHere, we show that the essential features of piezomagnetism can be reproduced\nwith optical phonons alone, which can be driven by light to large amplitudes\nwithout changing the volume and hence beyond the elastic limits of the\nmaterial. We exploit nonlinear, three-phonon mixing to induce the desired\ncrystal field distortions in the antiferromagnet CoF$_2$. Through this effect,\nwe generate a ferrimagnetic moment of 0.2 $\\mu_B$ per unit cell, nearly three\norders of magnitude larger than achieved with mechanical strain."
    },
    {
        "anchor": "On the mechanical modeling of the extreme softening/stiffening response\n  of axially loaded tensegrity prisms: We study the geometrically nonlinear behavior of uniformly compressed\ntensegrity prisms, through fully elastic and rigid--elastic models. The\npresented models predict a variety of mechanical behaviors in the regime of\nlarge displacements, including an extreme stiffening-type response, already\nknown in the literature, and a newly discovered, extreme softening behavior.\nThe latter may lead to a snap buckling event producing an axial collapse of the\nstructure. The switching from one mechanical regime to another depends on the\naspect ratio of the structure, the magnitude of the applied prestress, and the\nmaterial properties of the constituent elements. We discuss potential acoustic\napplications of such behaviors, which are related to the design and manufacture\nof tensegrity lattices and innovative phononic crystals.",
        "positive": "GAtor: A First Principles Genetic Algorithm for Molecular Crystal\n  Structure Prediction: We present the implementation of GAtor, a massively parallel, first\nprinciples genetic algorithm (GA) for molecular crystal structure prediction.\nGAtor is written in Python and currently interfaces with the FHI-aims code to\nperform local optimizations and energy evaluations using dispersion-inclusive\ndensity functional theory (DFT). GAtor offers a variety of fitness evaluation,\nselection, crossover, and mutation schemes. Breeding operators designed\nspecifically for molecular crystals provide a balance between exploration and\nexploitation. Evolutionary niching is implemented in GAtor by using machine\nlearning to cluster the dynamically updated population by structural similarity\nand then employing a cluster-based fitness function. Evolutionary niching\npromotes uniform sampling of the potential energy surface by evolving several\nsub-populations, which helps overcome initial pool biases and selection biases\n(genetic drift). The various settings offered by GAtor increase the likelihood\nof locating numerous low-energy minima, including those located in\ndisconnected, hard to reach regions of the potential energy landscape. The best\nstructures generated are re-relaxed and re-ranked using a hierarchy of\nincreasingly accurate DFT functionals and dispersion methods. GAtor is applied\nto a chemically diverse set of four past blind test targets, characterized by\ndifferent types of intermolecular interactions. The experimentally observed\nstructures and other low-energy structures are found for all four targets. In\nparticular, for Target II, 5-cyano-3-hydroxythiophene, the top ranked putative\ncrystal structure is a $Z^\\prime$=2 structure with P$\\bar{1}$ symmetry and a\nscaffold packing motif, which has not been reported previously."
    },
    {
        "anchor": "Anisotropic Thermal Conductivity of Exfoliated Black Phosphorus: We ascertain the anisotropic thermal conductivity of alumina passivated black\nphosphorus (BP), a reactive 2D nanomaterial with strong in-plane anisotropy. We\nmeasure the room temperature thermal conductivity by time-domain\nthermoreflectance for the three crystalline axes of exfoliated BP. The thermal\nconductivity along the zigzag direction (86 +/- 8 W/(m*K)) is ~2.5 times higher\nthan that of the armchair direction (34 +/- 4 W/(m*K)).",
        "positive": "How to calculate the degree of spin polarization in ferromagnets?: Different ways to define and to calculate the degree of spin polarization in\na ferromagnet are discussed, particularly with respect to spin-polarized\ntunneling and Andreev reflection at the boundary between a superconductor and\nferromagnet. As an example, the degrees of spin polarization for different\nexperiments in Fe and Ni are calculated in the framework of the local spin\ndensity approximation (LSDA) and used to illustrate the differences between\nvarious definitions of spin polarization."
    },
    {
        "anchor": "The band-gap of Tl-doped gallium nitride alloys: Structural and electronic properties of hypothetical zinc blende\nTl(x)Ga(1-x)N alloys have been investigated from first principles. The\nstructural relaxation, preformed within the LDA approach, leads to a linear\ndependence of the lattice parameter a on the Tl content x. In turn, band\nstructures obtained by MBJLDA calculations are significantly different from the\ncorresponding LDA results. The decrease of the band-gap in Tl-doped GaN\nmaterials (for x<0.25) is predicted to be a linear function of x, i.e. 0.08 eV\nper atomic % of thallium. The semimetallic character is expected for materials\nwith x>0.5. The obtained spin-orbit coupling driven splitting between the\nheavy-hole and split-off band at the Gamma point of the Brillouin zone in\nTl(x)Ga(1-x)N systems is significantly weaker when compared to that of Tl-doped\nInN materials.",
        "positive": "Multicomponent Density-Functional Theory for Electrons and Nuclei: We present a general multi-component density functional theory in which\nelectrons and nuclei are treated completely quantum mechanically, without the\nuse of a Born-Oppenheimer approximation. The two fundamental quantities in\nterms of which our theory is formulated are the nuclear N-body density and the\nelectron density expressed in coordinates referring to the nuclear framework.\nFor these two densities coupled Kohn-Sham equations are derived and the\nelectron-nuclear correlation functional is analyzed in detail. The formalism is\ntested on the hydrogen molecule $H_2$ and its positive ion $H_2^+$ using\nseveral approximations for the electron-nuclear correlation functional."
    },
    {
        "anchor": "Light-induced translation symmetry breaking via nonlinear phononics: Light has a wavelength that is usually longer than the size of the unit cell\nof crystals. Hence, even intense light pulses are not expected to break the\ntranslation symmetry of materials. However, certain materials, including\nKTaO$_3$, exhibit peaks in their Raman spectra corresponding to their Brillouin\nzone boundary phonons due to second-order Raman processes, which provide a\nmechanism to drive these phonons using intense midinfrared lasers. We\ninvestigated the possibility of breaking the translation symmetry of KTaO$_3$\nby driving its highest-frequency transverse optic mode $Q_{\\textrm{HX}}$ at the\n$X$ $(0,\\frac{1}{2},0)$ point. Our first principles calculations show that the\nenergy curve of the transverse acoustic mode $Q_{\\textrm{LZ}}$ at $X$ softens\nand develops a double-well shape as the value of the $Q_{\\textrm{HX}}$\ncoordinate is increased, while that of the other transverse acoustic component\n$Q_{\\textrm{LX}}$ hardens when the value of the $Q_{\\textrm{HX}}$ coordinate is\nsimilarly varied. We performed similar total energy calculations as a function\nof the $Q_{\\textrm{HX}}$ coordinate and electric field to extract the nonlinear\ncoupling between them. These were then used to construct the coupled equations\nof motion for the three phonon coordinates in the presence of an external pump\nterm on the $Q_{\\textrm{HX}}$ mode, which we numerically solved for a range of\npump frequencies and amplitudes. We find that 465 MV/cm is the smallest pump\namplitude that leads to an oscillation of the $Q_{\\textrm{LZ}}$ mode at a\ndisplaced position, hence, breaking the translation symmetry of the material.\nSuch highly intense light pulses cannot be generate by currently available\nlaser sources, and they have the possibility to damage the material.\nNevertheless, our work shows that light can in principle be used to break the\ntranslation symmetry of a material via nonlinear phononics.",
        "positive": "Magnetocrystalline anisotropy of Laves phase Fe$_2$Ta$_{1-x}$W$_x$ from\n  first principles - the effect of 3d-5d hybridisation: The magnetic properties of Fe$_2$Ta and Fe$_2$W in the hexagonal Laves phase\nare computed using density functional theory in the generalised gradient\napproximation, with the full potential linearised augmented plane wave method.\nThe alloy Fe$_2$Ta$_{1-x}$W$_x$ is studied using the virtual crystal\napproximation to treat disorder. Fe$_2$Ta is found to be ferromagnetic with a\nsaturation magnetization of $\\mu_0 M_\\text{s} = 0.66~\\mathrm{T}$ while, in\ncontrast to earlier computational work, Fe$_2$W is found to be ferrimagnetic\nwith $\\mu_0 M_\\text{s} = 0.35~\\mathrm{T}$. The transition from the ferri- to\nthe ferromagnetic state occurs for $x \\leq 0.1$. The magnetocrystalline\nanisotropy energy (MAE) is calculated to $1.25~\\mathrm{MJ/m^3}$ for Fe$_2$Ta\nand $0.87~\\mathrm{MJ/m^3}$ for Fe$_2$W. The MAE is found to be smaller for all\nvalues $x$ in Fe$_2$Ta$_{1-x}$W$_x$ than for the end compounds and it is\nnegative (in-plane anisotropy) for $0.1 \\leq x \\leq 0.9$. The MAE is carefully\nanalysed in terms of the electronic structure. Even though there are weak 5d\ncontributions to the density of states at the Fermi energy in both end\ncompounds, a reciprocal space analysis, using the magnetic force theorem,\nreveals that the MAE originates mainly from regions of the Brillouin zone with\nstrong 3d-5d hybridisation near the Fermi energy. Perturbation theory and its\napplicability in relation to the MAE is discussed."
    },
    {
        "anchor": "Bias voltage effects on tunneling magnetoresistance in\n  Fe/MgAl${}_2$O${}_4$/Fe(001) junctions: Comparative study with Fe/MgO/Fe(001)\n  junctions: We investigate bias voltage effects on the spin-dependent transport\nproperties of Fe/MgAl${}_2$O${}_4$/Fe(001) magnetic tunneling junctions (MTJs)\nby comparing them with those of Fe/MgO/Fe(001) MTJs. By means of the\nnonequilibrium Green's function method and the density functional theory, we\ncalculate bias voltage dependences of magnetoresistance (MR) ratios in both the\nMTJs. We find that in both the MTJs, the MR ratio decreases as the bias voltage\nincreases and finally vanishes at a critical bias voltage $V_{\\rm c}$. We also\nfind that the critical bias voltage $V_{\\rm c}$ of the MgAl${}_2$O${}_4$-based\nMTJ is clearly larger than that of the MgO-based MTJ. Since the in-plane\nlattice constant of the Fe/MgAl${}_2$O${}_4$/Fe(001) supercell is twice that of\nthe Fe/MgO/Fe(001) one, the Fe electrodes in the MgAl${}_2$O${}_4$-based MTJs\nhave an identical band structure to that obtained by folding the Fe band\nstructure of the MgO-based MTJs in the Brillouin zone of the in-plane wave\nvector. We show that such a difference in the Fe band structure is the origin\nof the difference in the critical bias voltage $V_{\\rm c}$ between the\nMgAl${}_2$O${}_4$- and MgO-based MTJs.",
        "positive": "Spin-orbit coupling effects on spin-phonon coupling in Cd2Os2O7: Spin-orbit coupling (SOC) is essential in understanding the properties of 5d\ntransition metal compounds, whose SOC value is large and almost comparable to\nother key parameters. Over the past few years, there have been numerous studies\non the SOC-driven effects of the electronic bands, magnetism, and spin-orbit\nentanglement for those materials with a large SOC. However, it is less studied\nand remains an unsolved problem in how the SOC affects the lattice dynamics.\nWe, therefore, measured the phonon spectra of 5d pyrochlore Cd2Os2O7 over the\nfull Brillouin zone to address the question by using inelastic x-ray scattering\n(IXS). Our main finding is a visible mode-dependence in the phonon spectra,\nmeasured across the metal-insulator transition at 227 K. We examined the SOC\nstrength dependence of the lattice dynamics and its spin-phonon (SP) coupling,\nwith first-principle calculations. Our experimental data taken at 100 K are in\ngood agreement with the theoretical results obtained with the optimized U = 2.0\neV with SOC. By scaling the SOC strength and the U value in the DFT\ncalculations, we demonstrate that SOC is more relevant than U to explaining the\nobserved mode-dependent phonon energy shifts with temperature. Furthermore, the\ntemperature dependence of the phonon energy can be effectively described by\nscaling SOC. Our work provides clear evidence of SOC producing a non-negligible\nand essential effect on the lattice dynamics of Cd2Os2O7 and its SP coupling."
    },
    {
        "anchor": "Enhanced surface plasmon polariton propagation induced by active\n  dielectrics: We present numerical simulations for the propagation of surface plasmon\npolaritons in a dielectric-metal-dielectric waveguide using COMSOL multiphysics\nsoftware. We show that the use of an active dielectric with gain that\ncompensates metal absorption losses enhances substantially plasmon propagation.\nFurthermore, the introduction of the active material induces, for a specific\ngain value, a root in the imaginary part of the propagation constant leading to\ninfinite propagation of the surface plasmon. The computational approaches\nanalyzed in this work can be used to define and tune the optimal conditions for\nsurface plasmon polariton amplification and propagation.",
        "positive": "Electronic, magnetic and galvanomagnetic properties of Co-based Heusler\n  alloys: possible states of a half-metallic ferromagnet and spin gapless\n  semiconductor: Parameters of the energy gap and, consequently, electronic, magnetic and\ngalvanomagnetic properties in different X$_2$YZ Heusler alloys can vary quite\nstrongly. In particular, half-metallic ferromagnets (HMFs) and spin gapless\nsemiconductors (SGSs) with almost 100% spin polarization of charge carriers are\npromising materials for spintronics. The changes in the electrical, magnetic\nand galvanomagnetic properties of the Co$_2$YSi (Y = Ti, V, Cr, Mn, Fe) and\nCo$_2$MnZ Heusler alloys (Z = Al, Si, Ga, Ge) in possible HMF and/or SGS states\nwere followed and their interconnection was established. Significant changes in\nthe values of the magnetization and residual resistivity were found. At the\nsame time, the correlations between the changes in these electronic and\nmagnetic characteristics depending on the number of valence electrons and spin\npolarization are observed."
    },
    {
        "anchor": "Experimental proof of moisture clog through neutron tomography in a\n  porous medium under truly one-directional drying: Structural failure of concrete buildings on fire and complete destruction of\nthe monolithic refractory lining during their drying stage are dangerous\nexamples of the effect of explosive spalling on partially saturated porous\nmedia. Several observations in both cases indicated the presence of moisture\naccumulation ahead of the drying front, which are in tune with the most common\ntheories on the explosive spalling of concrete. Previous studies have shown\nevidence of the existence of this phenomenon, however, they were biased by\nartifacts and experimental limitations (such as the beam hardening effect and\nchanges in the microstructure of the material due to the presence of pressure\nand temperature sensors). In the current work, rapid neutron tomography was\nused to investigate the in-operando drying behavior of a high-alumina\nrefractory castable, proposing a novel experimental layout aimed at a truly\none-dimensional drying front. This setup provided more realistic boundary\nconditions, such as the behavior of a larger wall heated from one of its sides,\nwhile also preventing some nonphysical artifacts (notably beam hardening). By\neliminating these aspects, a direct proof that moisture accumulates ahead of\nthe drying front was obtained. This work also lays the basis for further\nstudies focusing on the response sensitivity analysis to boundary conditions\nand other parameters (e.g., heating rates and properties of the sample related\nto the moisture clog formation), as well as useful data for the validation and\ncharacterization stages of numerical models of partially saturated porous\nmedia.",
        "positive": "Observation of magnetic vortex pairs at room temperature in a planar\n  \u03b1-Fe2O3/Co heterostructure: Vortices are among the simplest topological structures, and occur whenever a\nflow field `whirls' around a one-dimensional core. They are ubiquitous to many\nbranches of physics, from fluid dynamics to superconductivity and\nsuperfluidity, and are even predicted by some unified theories of particle\ninteractions, where they might explain some of the largest-scale structures\nseen in today's Universe. In the crystalline state, vortex formation is rare,\nsince it is generally hampered by long-range interactions: in ferroic materials\n(ferromagnetic and ferroelectric), vortices are only observed when the effects\nof the dipole-dipole interaction is modified by confinement at the nanoscale,\nor when the parameter associated with the vorticity does not couple directly\nwith strain. Here, we present the discovery of a novel form of vortices in\nantiferromagnetic (AFM) hematite ($\\alpha$-Fe$_2$O$_3$) epitaxial films, in\nwhich the primary whirling parameter is the staggered magnetisation.\nRemarkably, ferromagnetic (FM) topological objects with the same vorticity and\nwinding number of the $\\alpha$-Fe$_2$O$_3$ vortices are imprinted onto an\nultra-thin Co ferromagnetic over-layer by interfacial exchange. Our data\nsuggest that the ferromagnetic vortices may be merons (half-skyrmions, carrying\nan out-of-plane core magnetisation), and indicate that the vortex/meron pairs\ncan be manipulated by the application of an in-plane magnetic field,\nH$_{\\parallel}$, giving rise to large-scale vortex-antivortex annihilation."
    },
    {
        "anchor": "Manipulating antiferromagnets with magnetic fields: ratchet motion of\n  multiple domain walls induced by asymmetric field pulses: Future applications of antiferromagnets (AFs) in many spintronics devices\nrely on the precise manipulation of domain walls. The conventional approach\nusing static magnetic fields is inefficient due to the low susceptibility of\nAFs. Recently proposed electrical manipulation with spin-orbit torques is\nrestricted to metals with a specific crystal structure.\n  Here we propose an alternative, broadly applicable approach: using asymmetric\nmagnetic field pulses to induce controlled ratchet motion of AF domain walls.\n  The efficiency of this approach is based on three peculiarities of AF\ndynamics. First, a time-dependent magnetic field couples with an AF order\nparameter stronger than a static magnetic field, which leads to higher mobility\nof the domain walls. Second, the rate of change of the magnetic field couples\nwith the spatial variation of the AF order parameter inside the domain and this\nenables synchronous motion of multiple domain walls with the same structure.\nThird, tailored asymmetric field pulses in combination with static friction can\nprevent backward motion of domain walls and thus lead to the desired controlled\nratchet effect.\n  The proposed use of an external field, rather than internal spin-orbit\ntorques, avoids any restrictions on size, conductivity, and crystal structure\nof the AF material.\n  We believe that our approach paves a way for the development of new AF-based\ndevices based on controlled motion of AF domain walls.",
        "positive": "Multiple charging of InAs/GaAs quantum dots by electrons or holes:\n  addition energies and ground-state configurations: Atomistic pseudopotential plus configuration interaction calculations of the\nenergy needed to charge dots by either electrons or holes are described, and\ncontrasted with the widely used, but highly simplified two-dimensional\nparabolic effective mass approximation (2D-EMA). Substantial discrepancies are\nfound, especially for holes, regarding the stable electronic configuration and\nfilling sequence which defies both Hund's rule and the Aufbau principle."
    },
    {
        "anchor": "Success and breakdown of the T-matrix approximation for phonon-disorder\n  scattering: We examine the validity of the widely used T-matrix approximation for\ntreating phonon-disorder scattering by implementing an unfolding algorithm that\nallows simulation of disorder up to tens of millions of atoms. The T-matrix\napproximation breaks down for low-energy flexure phonons that play an important\nrole in thermal transport in two-dimensional materials. Furthermore, insights\nare developed into the success of the T-matrix approximation in describing\nmaximally mass disordered systems. To achieve this, the phonon unfolding\nformalism is generalized to describe mass disorder and strongly nonperturbative\nfeatures of the spectrum are connected to the Boltzmann quasiparticle picture.",
        "positive": "A DFT+U study of the segregation of Pt to the CeO$_{2-x}$\n  $\\Sigma3[1\\bar10]/(111)$ grain boundary: Grain boundaries (GBs) can be used as traps for solute atoms and defects, and\nthe interaction between segregants and GBs is crucial for understanding the\nproperties of nanocrystalline materials. In this study, we have systematically\ninvestigated the tendency of Pt to segregate as well as the interaction between\nPt and oxygen vacancies at the sigma 3/(111) GB of ceria (CeO2). The Pt atom\nhas a stronger tendency to segregate to the sigma 3/(111) GB than to the (111)\nand (110) free-standing surfaces, but the tendency is weaker than to the (100)\nfree-standing surface. Mechanic contributions (lattice distortion) play a\ndominant role in the strong tendency of Pt to segregate. At the\nPt-segregated-GB (Pt@GB), oxygen vacancies prefer to form spontaneously near Pt\nin the GB region. However, at the pristine GB (no Pt and no vacancies), oxygen\nvacancies form only under O-poor conditions. Thus, Pt segregation to the GB\npromotes the formation of oxygen vacancies, and their strong interactions\nenhance the interfacial cohesion. We propose that GBs fabricated close to the\nsurfaces of nanocrystalline ceria can trap Pt from the bulk or other types of\nsurface, resulting in the suppression of the accumulation of Pt on the surface\nunder redox reactions, especially under O-poor conditions."
    },
    {
        "anchor": "Evidence of topological edge states in a superconducting nonsymmorphic\n  nodal-line semimetal: Topological materials host fascinating low dimensional gapless states at the\nboundary. As a prominent example, helical topological edge states (TESs) of\ntwo-dimensional topological insulators (2DTIs) and their stacked\nthree-dimensional (3D) equivalent, weak topological insulators (WTIs), have\nsparked research enthusiasm due to their potential application in the next\ngeneration of electronics/spintronics with low dissipation. Here, we propose\nlayered superconducting material CaSn as a WTI with nontrivial Z2 as well as\nnodal line semimetal protected by crystalline non-symmorphic symmetry. Our\nsystematic angle-resolved photoemission spectroscopy (ARPES) investigation on\nthe electronic structure exhibits excellent agreement with the calculation.\nFurthermore, scanning tunnelling microscopy/spectroscopy (STM/STS) at the\nsurface step edge shows signatures of the expected TES. These integrated\nevidences from ARPES, STM/STS measurement and corresponding ab initio\ncalculation strongly support the existence of TES in the non-symmorphic nodal\nline semimetal CaSn, which may become a versatile material platform to realize\nmultiple exotic electronic states as well as topological superconductivity.",
        "positive": "Crossover Behavior in the Packing and Assembly of Multivalent\n  Lock-and-Key Colloids: Emergent behaviors occur in a vast array of systems across many scales, and\nare of fundamental physical importance because of the intrinsic difficulty in\nlinking microscopic system properties to macroscopic behaviors. Here we study\nthe emergent self-assembly behavior of model systems of recently synthesized\nfamilies of concave dimpled hard spheres, or lock-and-key colloids. We find\nthat as dimple size increases each family exhibits a crossover from a structure\nthat does not reflect the particle symmetry to one that does and, surprisingly,\nthe point at which this crossover occurs is approximately independent of the\nparticle symmetry. Using a combination of numerical and analytic techniques we\nstudy systems at infinite and finite pressure, and find different common\ncontrol parameters in each limit. Our results suggest there exists a set of\nexperimentally realizable colloidal systems that exhibit complex emergent\nbehaviors that can be traced to a common underlying microscopic control\nparameter."
    },
    {
        "anchor": "Wafer-Scale Assembly of Semiconductor Nanowire Arrays by Contact\n  Printing: Controlled and uniform assembly of \"bottom-up\" nanowire (NW) materials with\nhigh scalability has been one of the significant bottleneck challenges facing\nthe potential integration of nanowires for both nano and macro electronic\ncircuit applications. Many efforts have focused on tackling this challenge, and\nwhile significant progress has been made, still most presented approaches lack\neither the desired controllability in the positioning of nanowires or the\nneeded uniformity over large scales. Here, we demonstrate wafer-scale assembly\nof highly ordered, dense, and regular arrays of NWs with high uniformity and\nreproducibility through a simple contact printing process. We demonstrate\ncontact printing as a versatile strategy for direct transfer and controlled\npositioning of various NW materials into complex structural configurations on\nsubstrates. The assembled NW pitch is shown to be readily modulated through the\nsurface chemical treatment of the receiver substrate, with the highest density\napproaching ~8 NW/um, ~95% directional alignment and wafer-scale uniformity.\nFurthermore, we demonstrate that our printing approach enables large-scale\nintegration of NW arrays for various device structures on both Si and plastic\nsubstrates, with a controlled semiconductor channel width, and therefore ON\ncurrent, ranging from a single NW (~10 nm) and up to ~250 um, consisting of a\nparallel array of over 1,250 NWs.",
        "positive": "Ultrafast reversal of the ferroelectric polarization by a midinfrared\n  pulse: We calculate the ferroelectric polarization dynamics induced by a femtosecond\nmidinfrared pulse as measured in the recent experiment by R. Mankowsky et al.,\nPhys. Rev. Lett. 118, 197601 (2017). It is due to the nonlinear coupling of the\nexcited infrared-active phonon with the ferroelectric mode or to the excitation\nof the ferroelectric mode itself depending on the pulse frequency. To begin\nwith, we write the LiNbO$_3$ crystal symmetry invariant thermodynamic potential\nincluding electric field and nonlinear phonon coupling terms. We solve the\nequations of motion determined by this potential for phonon coordinates\nnumerically in classical approximation. We explain the transient polarization\nreversal observed in the experiment by action of the depolarizing electric\nfield which is due to bound charges at the polarization domain boundaries and\ngive a reasonable estimate for its value. We argue that the polarization could\nbe ultimately reversed when this field is screened."
    },
    {
        "anchor": "Direct Evidence for Suppression of the Kondo Effect due to Pure Spin\n  Current: We study the effect of a pure spin current on the Kondo singlet in a diluted\nmagnetic alloy using non-local lateral spin valve structures with highly spin\npolarized Co2FeSi electrodes. Temperature dependence of the non-local spin\nsignals shows a sharp reduction with decreasing temperature, followed by a\nplateau corresponding to the low temperature Fermi liquid regime below the\nKondo temperature (TK). The spin diffusion length of the Kondo alloy is found\nto increase with the evolution of spin accumulation. The results are in\nagreement with the intuitive description that the Kondo singlet cannot survive\nany more in sufficiently large spin accumulation even below TK.",
        "positive": "Resonant Lifetime of Core-Excited Organic Adsorbates from First\n  Principles: We investigate by first-principles simulations the resonant electron-transfer\nlifetime from the excited state of an organic adsorbate to a semiconductor\nsurface, namely isonicotinic acid on rutile TiO$_2$(110). The\nmolecule-substrate interaction is described using density functional theory,\nwhile the effect of a truly semi-infinite substrate is taken into account by\nGreen's function techniques. Excitonic effects due to the presence of\ncore-excited atoms in the molecule are shown to be instrumental to understand\nthe electron-transfer times measured using the so-called core-hole-clock\ntechnique. In particular, for the isonicotinic acid on TiO$_2$(110), we find\nthat the charge injection from the LUMO is quenched since this state lies\nwithin the substrate band gap. We compute the resonant charge-transfer times\nfrom LUMO+1 and LUMO+2, and systematically investigate the dependence of the\nelastic lifetimes of these states on the alignment among adsorbate and\nsubstrate states."
    },
    {
        "anchor": "Nature of the metal-insulator transition in few-unit-cell-thick LaNiO3\n  films: The nature of the metal insulator transition in thin films and superlattices\nof LaNiO3 with only few unit cells in thickness remains elusive despite\ntremendous effort. Quantum confinement and epitaxial strain have been evoked as\nthe mechanisms, although other factors such as growth-induced disorder, cation\nnon-stoichiometry, oxygen vacancies, and substrate-film interface quality may\nalso affect the observable properties in the ultrathin films. Here we report\nresults obtained for near-ideal LaNiO3 films with different thicknesses and\nterminations grown by atomic layer-by-layer laser molecular beam epitaxy on\nLaAlO3 substrates. We find that the room-temperature metallic behavior persists\nuntil the film thickness is reduced to an unprecedentedly small 1.5 unit cells\n(NiO2 termination). Electronic structure measurements using x-ray absorption\nspectroscopy and first-principles calculation suggest that oxygen vacancies\nexisting in the films also contribute to the metal insulator transition.",
        "positive": "Optical spectra and structure of CdP4 nanoclusters fabricated by\n  incorporation into zeolite and laser ablation: CdP4 nanoclusters were fabricated by incorporation into the pores of zeolite\nNa-X and by deposition of the clusters onto a quartz substrate using laser\nablation-evaporation technique. Absorption and photoluminescence (PL) spectra\nof CdP4 nanoclusters in zeolite were measured at the temperatures of 4.2, 77\nand 293 K. Both absorption and PL spectra consist of two blue shifted bands. We\nperformed DFT calculations to determine the most stable clusters configuration\nin the size region up to size of the zeolite Na-X supercage. The bands observed\nin absorption and PL spectra were attributed to emission of (CdP4)3 and (CdP4)4\nclusters with binding energies of 3.78 eV and 4.37 eV per atom respectively.\nThe Raman spectrum of CdP4 clusters in zeolite proved the fact of creation of\n(CdP4)3 and (CdP4)4 clusters in zeolite pores. The PL spectrum of CdP4 clusters\nproduced by laser ablation consists of single band that was attributed to\nemission of (CdP4)4 cluster."
    },
    {
        "anchor": "Electronic and dynamical properties of CeRh$_{2}$As$_{2}$: Role of\n  Rh$_{2}$As$_{2}$ layers and expected hidden orbital order: Recently discovered heavy fermion CeRh$_{2}$As$_{2}$ compound crystallizes in\nthe nonsymmorphic $P4/nmm$ symmetry, which enables the occurrence of\ntopological protection. Experimental results show that this material exhibits\nunusual behavior, which is manifested by the appearance of two superconducting\nphases. In this work, we uncover and discuss a role of Rh$_{2}$As$_{2}$ layers\nand their impact on the electronic and dynamical properties of the system. The\nlocation of Ce atoms between two non-equivalent layers allows for the\nrealization of hidden orbital order. We point out that the electronic band\nstructure around the Fermi level is associated mostly with Ce $4f$ and Rh $4d$\norbitals and suggest the occurrence of the Lifshitz transition induced by the\nexternal magnetic field. We discuss also the role played by the $f$--$d$\norbital hybridization in the electronic band structure.",
        "positive": "Limiting scattering processes in high-mobility InSb quantum wells grown\n  on GaSb buffer systems: We present molecular beam epitaxial grown single- and double-side\n$\\delta$-doped InAlSb/InSb quantum wells with varying distances down to 50 nm\nto the surface on GaSb metamorphic buffers. We analyze the surface morphology\nas well as the impact of the crystalline quality on the electron transport.\nComparing growth on GaSb and GaAs substrates indicates that the structural\nintegrity of our InSb quantum wells is solely determined by the growth\nconditions at the GaSb/InAlSb transition and the InAlSb barrier growth. The\ntwo-dimensional electron gas samples show high mobilities of up to 349 000\ncm$^2$/Vs at cryogenic temperatures and 58 000 cm$^2$/Vs at room temperature.\nWith the calculated Dingle ratio and a transport lifetime model, ionized\nimpurities predominantly remote from the quantum well are identified as the\ndominant source of scattering events. The analysis of the well pronounced\nShubnikov$-$de Haas oscillations reveals a high spin-orbit coupling with an\neffective $g$-factor of $-38.4$ in our samples. Along with the smooth surfaces\nand long mean free paths demonstrated, our InSb quantum wells are increasingly\ncompetitive for nanoscale implementations of Majorana mode devices."
    },
    {
        "anchor": "Crossover of magnetoresistance in the zerogap half-metallic Heusler\n  alloy Fe2CoSi: This work reports on the band structure and magneto-transport investigations\nof the inverse Heusler compound Fe2CoSi. The first-principles calculations\nreveal that Fe2CoSi has a very peculiar band structure with a conducting\nproperty in the majority spin channel and a nearly zero bandgap in the minority\nspin channel. The synthesized Fe2CoSi sample shows a high-ordered inverse\nHeusler structure with a magnetic moment of 4.88 {\\mu}B at 5 K and a high Curie\ntemperature of 1038 K. With increasing temperature, a crossover from positive\nto negative magnetoresistance (MR) is observed. Complemented with the Hall\neffect measurements, we suggest the intriguing crossover of MR can be ascribed\nto the dominant spin carriers changing from the gapless minority spin channel\nto the majority spin channel at Fermi level.",
        "positive": "Optically Isotropic and Monoclinic Ferroelectric Phases in PZT Single\n  Crystals near Morphotropic Phase Boundary: We report the finding of unusual scale-dependent symmetry below the\nferroelectric Curie temperature in the perovskite Pb(Zr1-xTix)O3 single\ncrystals of morphotropic phase boundary compositions. The crystals of\ntetragonal symmetry (from x-ray diffraction experiments) on sub-micrometer\nscale exhibit a macroscopic (optically determined) cubic symmetry. This\npeculiar optical isotropy is explained by the anomalously small size of\ntetragonal ferroelectric domains. Upon further cooling the crystals transform\nto the phase consisting of micrometer-sized domains of monoclinic Cm symmetry."
    },
    {
        "anchor": "Efficient implementation of a van der Waals density functional:\n  Application to double-wall carbon nanotubes: We present an efficient implementation of the van der Waals density\nfunctional of Dion et al [Phys. Rev. Lett. 92, 246401 (2004)], which expresses\nthe nonlocal correlation energy as a double spacial integral. We factorize the\nintegration kernel and use fast Fourier transforms to evaluate the\nselfconsistent potential, total energy, and atomic forces, in N log(N)\noperations. The resulting overhead in total computational cost, over semilocal\nfunctionals, is very moderate for medium and large systems. We apply the method\nto calculate the binding energies and the barriers for relative translation and\nrotation in double-wall carbon nanotubes.",
        "positive": "Transport through correlated quantum dots: An investigation using the\n  functional renormalization group: Calculations using the (exact) fermionic functional renormalization group are\nusually truncated at the second order of the corresponding hierarchy of coupled\nordinary differential equations. We present a method for the systematic\ndetermination of higher order vertex functions. This method is applied to a\nstudy of transport properties of various correlated quantum dot systems. It is\nshown that for large Coulomb correlations higher order vertex functions cannot\nbe neglected, and a static approximation is insufficient."
    },
    {
        "anchor": "Nanoscale Graphene Disk: A Natural Functionally Graded Material --The\n  Thermal Conductivity of Nanoscale Graphene Disk by Molecular Dynamics\n  Simulation: In this letter, we investigate numerically (by non-equilibrium molecular\ndynamics) and analytically the thermal conductivity of nanoscale graphene disks\n(NGDs), and discussed the possibility to realize FGM with only one material,\nNGDs. We found that the NGD has a graded thermal conductivity and can be used\nas FGM in a large temperature range. Moreover, we show the dependent of NGDs'\nthermal conductivity on radius and temperature. Our study may inspire\nexperimentalists to develop NGD based FGMs and help heat removal of hot spots\non chips by graphene.",
        "positive": "Observation by resonant angle-resolved photoemission of a critical\n  thickness for 2-dimensional electron gas formation in SrTiO$_3$ embedded in\n  GdTiO$_3$: For certain conditions of layer thickness, the interface between GdTiO$_3$\n(GTO) and SrTiO$_3$ (STO) in multilayer samples has been found to form a\ntwo-dimensional electron gas (2DEG) with very interesting properties including\nhigh mobilities and ferromagnetism. We have here studied two trilayer samples\nof the form [2 nm GTO/1.0 or 1.5 unit cells STO/10 nm GTO] as grown on (001)\n(LaAlO$_3$)$_{0.3}$(Sr$_2$AlTaO$_6$)$_{0.7}$ (LSAT), with the STO layer\nthicknesses being at what has been suggested is the critical thickness for 2DEG\nformation. We have studied these with Ti-resonant angle-resolved (ARPES) and\nangle-integrated photoemission and find that the spectral feature in the\nspectra associated with the 2DEG is present in the 1.5 unit cell sample, but\nnot in the 1.0 unit cell sample. We also observe through core-level spectra\nadditional states in Ti and Sr, with the strength of a low-binding-energy state\nfor Sr being associated with the appearance of the 2DEG, and we suggest it to\nhave an origin in final-state core-hole screening."
    },
    {
        "anchor": "A two-speed model for finite-strain elasto-plasticity: This work presents a new modeling approach to macroscopic, polycrystalline\nelasto-plasticity starting from first principles and a few well-defined\nstructural assumptions, incorporating the mildly rate-dependent (viscous)\nnature of plastic flow and the microscopic origins of plastic deformations. For\nthe global dynamics, we start from a two-stage time-stepping scheme, expressing\nthe fact that in most real materials plastic flow is much slower than elastic\ndeformations, and then perform a detailed analysis of the slow-loading limit\npassage. In this limit, a rate-independent evolution can be expected, but this\nbrings with it the possibility of jumps (relative to the \"slow\" time).\nTraditionally, the dynamics on the jump transients often remain unspecified,\nwhich leads to ambiguity and deficiencies in the energy balance. In order to\nremedy this, the present approach precisely describes the energetics on the\njump transients as the limit of the rate-dependent evolutions at \"singular\npoints\". It turns out that rate-dependent behavior may (but does not have to)\nprevail on the jump transients. Based on this, we introduce the new solution\nconcept of \"two-speed solutions\" to the elasto-plastic evolutionary system,\nwhich incorporates a \"slow\" and a \"fast\" time scale, the latter of which\nparametrizes the jump transients.",
        "positive": "Concentration phase diagram of Ba(x)Sr(1-x)TiO3 solid solutions: Method of derivation of phenomenological thermodynamic potential of solid\nsolutions is proposed in which the interaction of the order parameters of\nconstituents is introduced through the account of elastic strain due to misfit\nof the lattice parameters of the end-members. The validity of the method is\ndemonstrated for Ba(x)Sr(1-x)TiO3 system being a typical example of\nferroelectric solid solution. Its phase diagram is determined using\nexperimental data for the coefficients in the phenomenological potentials of\nSrTiO3 and BaTiO3. In the phase diagram of the Ba(x)Sr(1-x)TiO3 system for\nsmall Ba concentration, there are a tricritical point and two multiphase points\none of which is associated with up to 6 possible phases."
    },
    {
        "anchor": "Incommensurate magnetic modulation in K-rich cryptomelane,\n  K$_x$Mn$_8$O$_{16}$ ($x\\approx1.46$): Cryptomelane is a hollandite-like material consisting of K$^+$ cations in an\n$\\alpha$-MnO$_2$ tunnel-like crystallographic motif. A sample with\nstoichiometry K$_{1.461(4)}$Mn$_8$O$_{16}$ has been synthesised and its\nmagnetic properties investigated using variable-temperature magnetic\nsusceptibility, heat capacity, and neutron powder diffraction. Three distinct\nmagnetic transitions at $184$\\,K, $54.5$\\,K, and $24$\\,K are assigned to\nK$_{1.461(4)}$Mn$_8$O$_{16}$. Magnetic Bragg peaks emerge below $54.5$\\,K, and\nfrom their positions they indicate a modulated magnetic structure which is\nincommensurate with the crystallographic nuclear structure. The model\nconsistent with the data is a dual-$\\vec{k}_\\mathrm{mag}$ structure with a\ncanted ferrimagnetic $\\vec{k}_\\mathrm{mag}=0$ component and an incommensurate\n$\\vec{k}_\\mathrm{mag}=(0,0,k_z)$ [$k_z=0.36902(15)$] component, with the latter\nmost likely to be of the helical type formerly proposed for this material.\nBelow 24\\,K, there is a magnetic transition, which gives rise to a different\nset of magnetic Bragg peaks indicative of a highly complex magnetic structure.",
        "positive": "The Laser Ablation Production of Platinum Nitride and its Possible\n  Structure: The synthesis of platinum nitride by the laser ablation method is reported.\nThe spectroscopic results show that nitrogen is in interstitial sites of\nplatinum as N-units, contradicting the accepted configuration for PtN2 where it\nis as N2-units. To elucidate this point we did density functional calculations\nto correlate composition with nitrogen sites. For dilute nitrogen\nconcentrations, x < 0.2, nitrogen would be in six-fold coordinated sites\n(octahedral interstices) as N-units. For 0.2 < x < 1.5, nitrogen would be in\ntetrahedral interstices as N-units. Only for x > 1.5 the N2-configuration in\noctahedral sites is attained."
    },
    {
        "anchor": "Giant magnetic anisotropy energy and long coherence time of uranium\n  substitution on defected Al2O3(0001): Nanomagnets with giant magnetic anisotropy energy and long coherence time are\ndesired for various technological innovations such as quantum information\nprocession and storage. Based on the first-principles calculations and model\nanalyses, we demonstrate that a single uranium atom substituting Al on the\nAl2O3(0001) surface may have high structural stability and large magnetic\nanisotropy energy up to 48 meV per uranium atom. As the magnetization resides\nin the localized f-shell and is not much involved in chemical bonding with\nneighbors, long coherence time up to ~1.6 mS can be achieved for the quantum\nspin states. These results suggest a new strategy for the search of ultrasmall\nmagnetic units for diverse applications in the quantum information era.",
        "positive": "Modulated structure in the martensite phase of Ni1.8Pt0.2MnGa: a neutron\n  diffraction study: 7M orthorhombic modulated structure in the martensite phase of Ni1.8Pt0.2MnGa\nis reported by powder neutron diffraction study, which indicates that it is\nlikely to exhibit magnetic field induced strain. The change in the unit cell\nvolume is less than 0.5% between the austenite and martensite phases, as\nexpected for a volume conserving martensite transformation. The magnetic\nstructure analysis shows that the magnetic moment in the martensite phase is\nhigher compared to Ni2MnGa, which is in good agreement with magnetization\nmeasurement."
    },
    {
        "anchor": "Nearly total spin polarization in La2/3Sr1/3MnO3 from tunneling\n  experiments: We have performed magnetotransport measurements on La2/3Sr1/3MnO3 / SrTiO3 /\nLa2/3Sr1/3MnO3 magnetic tunnel junctions. A magnetoresistance ratio of more\nthan 1800 % is obtained at 4K, from which we infer an electrode spin\npolarization of at least 95 %. This result strongly underscores the\nhalf-metallic nature of mixed-valence manganites and demonstrates its\ncapability as a spin analyzer. The magnetoresistance extends up to temperatures\nof more than 270K. We argue that these improvements over most previous works\nmay result from optimizing the patterning process for oxide heterostructures.",
        "positive": "Humble planar defects in SiGe nanopillars: We report a new \\{001\\} planar defect found in SiGe nanopillars. The defect\nstructure, determined by atomic resolution electron microscopy, matches the\nHumble defect model proposed for diamond. We also investigated several possible\nvariants of the Humble structure using first principles calculations and found\nthat the one lowest in energy was also in best agreement with the STEM images.\nThe pillar composition has been analyzed with electron energy loss\nspectroscopy, which hints at how the defect is formed. Our results show that\nthe structure and formation process of defects in nanostructured group IV\nsemiconductors can be different from their bulk counterparts."
    },
    {
        "anchor": "Challenges in Band Alignment between Semiconducting Materials: A Case of\n  Rutile and Anatase TiO$_2$: This topical review focuses on the recently active debate on the band\nalignment between two polymorphs of TiO$_2$, rutile and anatase. A summary is\ngiven to the popular methods for measurement and calculation of band alignment\nbetween materials. We point out, through examination of recently experimental\nand theoretical reports, that the outstanding discrepancy in the band alignment\nbetween two TiO$_2$ phases is attributed to factors that influence band\nalignment rather than needs a definite answer of which band alignment is right.\nAccording to an important factor, the presence of an interface, a new\nclassification of band alignment is proposed as the coupled and intrinsic band\nalignments. This classification indeed reveals that the rutile/anatase\ninterface can qualitatively change the type of their band alignment. However,\nfurther systematic information of the interface and other factors that\ninfluence band alignment will be needed to understand changes in energy bands\nof materials better. The results obtained from discussion of the band alignment\nbetween rutile and anatase may also work for the band alignment between other\nsemiconductors.",
        "positive": "Symbolic Regression in Materials Science: We showcase the potential of symbolic regression as an analytic method for\nuse in materials research. First, we briefly describe the current\nstate-of-the-art method, genetic programming-based symbolic regression (GPSR),\nand recent advances in symbolic regression techniques. Next, we discuss\nindustrial applications of symbolic regression and its potential applications\nin materials science. We then present two GPSR use-cases: formulating a\ntransformation kinetics law and showing the learning scheme discovers the\nwell-known Johnson-Mehl-Avrami-Kolmogorov (JMAK) form, and learning the Landau\nfree energy functional form for the displacive tilt transition in perovskite\nLaNiO$_3$. Finally, we propose that symbolic regression techniques should be\nconsidered by materials scientists as an alternative to other\nmachine-learning-based regression models for learning from data."
    },
    {
        "anchor": "Pressure-induced electro-switching of polymer/nano-graphene composites: The pressure and temperature dependency of the electrical conductivity of\npoly(vinyl alcohol)/poly(vinyl pyrrolidone) (1/1, w/w) and poly(vinyl alcohol)\nand composites with dispersed nano-graphene platelets were studied. Above the\ncritical platelet fraction for electric charge percolation, the composites\nfunction as pressure-induced electro-switches. The conductor to insulator\ntransition is optimally intense and stable. The electrical conductivity drops\nby two orders of magnitude at a critical pressure around 750 bars. The\ntransition is stable over tenths of degrees above room temperature. The\nreduction of the conductivity upon pressure results from the competition\nbetween the pressure dependencies of the polarizability of the polymer matrix\nand the inter-platelet separation, respectively. Both contributions control the\nfluctuation induced tunneling of electrons through the polymer barrier\nseparating adjusting conductive platelets. The role of the local electric field\nat the polymer-platelet interfaces by assisting tunneling is suppressed by the\ndecrease of the polarizability upon pressure.",
        "positive": "Hydrogen release at metal-oxide interfaces: A first principle study of\n  hydrogenated Al/SiO$_2$ interfaces: The Anode Hydrogen Release (AHR) mechanism at interfaces is responsible for\nthe generation of defects, that traps charge carriers and can induce dielectric\nbreakdown in Metal-Oxide-Semiconductor Field Effect Transistors. The AHR has\nbeen extensively studied at Si/SiO$_2$ interfaces but its characteristics at\nmetal-silica interfaces remain unclear. In this study, we performed Density\nFunctional Theory (DFT) calculations to study the hydrogen release mechanism at\nthe typical Al/SiO$_2$ metal-oxide interface. We found that interstitial\nhydrogen atoms can break interfacial Al-Si bonds, passivating a Si $sp^3$\norbital. Interstitial hydrogen atoms can also break interfacial Al-O bonds, or\nbe adsorbed at the interface on aluminum, forming stable Al-H-Al bridges. We\nshowed that hydrogenated O-H, Si-H and Al-H bonds at the Al/SiO$_2$ interfaces\nare polarized. The resulting bond dipole weakens the O-H and Si-H bonds, but\nstrengthens the Al-H bond under the application of a positive bias at the metal\ngate. Our calculations indicate that Al-H bonds and O-H bonds are more\nimportant than Si-H bonds for the hydrogen release process."
    },
    {
        "anchor": "Light-Induced Nonthermal Phase Transition to the Topological Crystalline\n  Insulator State in SnSe: Femtosecond pulses have been used to reveal hidden broken symmetry states and\ninduce transitions to metastable states. However, these states are mostly\ntransient and disappear after laser removal. Photoinduced phase transitions\ntowards crystalline metastable states with a change of topological order are\nrare and difficult to predict and realize experimentally. Here, by using\nconstrained density functional perturbation theory and accounting for\nlight-induced quantum anharmonicity, we show that ultra-fast lasers can\npermanently transform the topologically-trivial orthorhombic structure of SnSe\ninto the topological crystalline insulating rocksalt phase via a first-order\nnon-thermal phase transition. We describe the reaction path and evaluate the\ncritical fluence and the possible decay channels after photoexcitation. Our\nsimulations of the photoexcited structural and vibrational properties are in\nexcellent agreement with recent pump-probe data in the intermediate fluence\nregime below the transition with an error on the curvature of the quantum free\nenergy of the photoexcited state that is smaller than 2%.",
        "positive": "Silicon nanostructures toxicity. An ab inito approach: Silicon nanoparticles are widely used in the medical area and until now they\nhave not manifested toxicological effects in humans beings. In order to\nunderstand the physical properties that determine their low-toxicity, we\nperform ab initio computational simulations of silicon nanoclusters, pure,\np-doped and hollow structured. The topological and electronic properties\nobtained pointed out to the number of dangling bonds and electronic density as\nfundamental parameters to locate active sites and directly related to toxicity,\nbesides the size and surface chemistry of the silicon nanoparticle."
    },
    {
        "anchor": "Room temperature polarization in the ferrimagnetic Ga2-xFexO3 ceramics: The effect of the Fe-Ga ratio on the magnetic and electric properties of the\nmultiferroic Ga2-xFexO3 compound has been studied in order to determine the\ncomposition range exhibiting magnetic and electric orders coexistence and their\ncritical temperatures. A magnetoelectric phase diagram, showing the evolution\nof both the Neel magnetic ordering temperature and the electric ordering\ntemperature, versus the iron content has been established for x values between\n0.9 and 1.4. While the ferrimagnetic Neel temperature increases with the iron\ncontent, the electric ordering temperature shows an opposite trend. The\nelectric polarization has been found to exist far above room temperature for\nthe x value of 1.1 composition which shows the highest observed electric\nordering temperature of approx. 580K. The compounds with x values of 1.3 and\n1.4 are ferrimagnetic-electric relaxors with both properties coexisting at room\ntemperature.",
        "positive": "Nanometer Resolution Elemental Mapping in Graphene-based TEM Liquid\n  Cells: We demonstrate a new design of graphene liquid cell consisting of a thin\nlithographically patterned hexagonal boron nitride crystal encapsulated from\nboth sides with graphene windows. The ultra-thin window liquid cells produced\nhave precisely controlled volumes and thicknesses, and are robust to repeated\nvacuum cycling. This technology enables exciting new opportunities for liquid\ncell studies, providing a reliable platform for high resolution transmission\nelectron microscope imaging and spectral mapping. The presence of water was\nconfirmed using electron energy loss spectroscopy (EELS) via the detection of\nthe oxygen K-edge and measuring the thickness of full and empty cells. We\ndemonstrate the imaging capabilities of these liquid cells by tracking the\ndynamic motion and interactions of small metal nanoparticles with diameters of\n0.5-5 nm. We further present an order of magnitude improvement in the\nanalytical capabilities compared to previous liquid cell data, with 1 nm\nspatial resolution elemental mapping achievable for liquid encapsulated\nbimetallic nanoparticles using energy dispersive X-ray spectroscopy (EDXS)."
    },
    {
        "anchor": "Gate-Tuned Thermoelectric Power in Black Phosphorus: The electric field effect is a useful means of elucidating intrinsic material\nproperties as well as for designing functional devices. The\nelectric-double-layer transistor (EDLT) enables the control of carrier density\nin a wide range, which is recently proved to be an effective tool for the\ninvestigation of thermoelectric properties. Here, we report the gate-tuning of\nthermoelectric power in a black phosphorus (BP) single crystal flake with the\nthickness of 40 nm. Using an EDLT configuration, we successfully control the\nthermoelectric power (S), and find that the S of ion-gated BP reached +510\n$\\mu$V/K at 210 K in the hole depleted state, which is much higher than the\nreported bulk single crystal value of +340 $\\mu$V/K at 300 K. We compared this\nexperimental data with the first-principles-based calculation and found that\nthis enhancement is qualitatively explained by the effective thinning of the\nconduction channel of the BP flake and non-uniformity of the channel owing to\nthe gate operation in a depletion mode. Our results provide new opportunities\nfor further engineering BP as a thermoelectric material in nanoscale.",
        "positive": "Size-dependent electronic-transport mechanism and sign reversal of\n  magnetoresistance in Nd0.5Sr0.5CoO3: A detailed investigation of electronic-transport properties of Nd0.5Sr0.5CoO3\nhas been carried out as a function of grain size ranging from micrometer order\ndown to an average size of 28 nm. Interestingly, we observe a size induced\nmetal-insulator transition in the lowest grain size sample while the bulk-like\nsample is metallic in the whole measured temperature regime. An analysis of the\ntemperature dependent resistivity in the metallic regime reveals that the\nelectron-electron interaction is the dominating mechanism while other processes\nlike electron-magnon and electron-phonon scatterings are also likely to be\npresent. The fascinating observation of enhanced low temperature upturn and\nminimum in resistivity on reduction of grain size is found due to\nelectron-electron interaction (quantum interference effect). This effect is\nattributed to enhanced disorder on reduction of grain size. Interestingly, we\nobserved a cross over from positive to negative magnetoresistance in the low\ntemperature regime as the grain size is reduced. This observed sign reversal is\nattributed to enhanced phase separation on decreasing the grain size of the\ncobaltite."
    },
    {
        "anchor": "$\u03b2$-Ga$_2$O$_3$ Nano-membrane Negative Capacitance Field-effect\n  Transistor with Steep Subthreshold Slope for Wide Bandgap Logic Applications: Steep-slope $\\beta$-Ga$_2$O$_3$ nano-membrane negative capacitance\nfield-effect transistors (NC-FETs) are demonstrated with ferroelectric hafnium\nzirconium oxide in gate dielectric stack. Subthreshold slope less than 60\nmV/dec at room temperature is obtained for both forward and reverse gate\nvoltage sweeps with a minimum value of 34.3 mV/dec at reverse gate voltage\nsweep and 53.1 mV/dec at forward gate voltage sweep at $V_{DS}$=0.5 V.\nEnhancement-mode operation with threshold voltage ~0.4 V is achieved by tuning\nthe thickness of $\\beta$-Ga$_2$O$_3$ membrane. Low hysteresis of less than 0.1\nV is obtained. The steep-slope, low hysteresis and enhancement-mode\n$\\beta$-Ga$_2$O$_3$ NC-FETs are promising as nFET candidate for future wide\nbandgap CMOS logic applications.",
        "positive": "Symmetry Breaking and Order in the Age of Quasicrystals: The discovery of quasicrystals has changed our view of some of the most basic\nnotions related to the condensed state of matter. Before the age of\nquasicrystals, it was believed that crystals break the continuous translation\nand rotation symmetries of the liquid-phase into a discrete lattice of\ntranslations, and a finite group of rotations. Quasicrystals, on the other\nhand, possess no such symmetries-there are no translations, nor, in general,\nare there any rotations, leaving them invariant. Does this imply that no\nsymmetry is left, or that the meaning of symmetry should be revised? We review\nthis and other questions related to the liquid-to-crystal symmetry-breaking\ntransition using the notion of indistinguishability. We characterize the\norder-parameter space, describe the different elementary excitations, phonons\nand phasons, and discuss the nature of dislocations-keeping in mind that we are\nnow living in the age of quasicrystals."
    },
    {
        "anchor": "The Li-F-H Ternary System at High Pressures: Evolutionary crystal structure prediction searches have been employed to\nexplore the ternary Li-F-H system at 300 GPa. Metastable phases were uncovered\nwithin the static lattice approximation, with LiF$_3$H$_2$, LiF$_2$H,\nLi$_3$F$_4$H, LiF$_4$H$_4$, Li$_2$F$_3$H and LiF$_3$H lying within 50 meV/atom\nof the 0 K convex hull. All of these phases contain H$_n$F$_{n+1}^-$ ($n$ = 1;\n2) anions, and Li$^+$ cations. Other structural motifs such as LiF slabs,\nH$_3^+$ molecules, and F$^{\\delta -}$ ions are present in some of the low\nenthalpy Li-F-H structures. The bonding within the H$_n$F$_{n+1}^-$ molecules,\nwhich may be bent or linear, symmetric or asymmetric, is analyzed. The five\nphases closest to the hull are insulators, while LiF$_3$H is metallic and\npredicted to have a vanishingly small superconducting critical temperature.\nThis study lays the foundation for future investigations of the role of\ntemperature and anharmonicity on the stability and properties of compounds and\nalloys in the Li-F-H ternary system.",
        "positive": "Interatomic Potential for Silicon Defects and Disordered Phases: We develop an empirical potential for silicon which represents a considerable\nimprovement over existing models in describing local bonding for bulk defects\nand disordered phases. The model consists of two- and three-body interactions\nwith theoretically motivated functional forms that capture chemical and\nphysical trends as explained in a companion paper. The numerical parameters in\nthe functional form are obtained by fitting to a set of ab initio results from\nquantum mechanical calculations based on density functional theory in the local\ndensity approximation, which include various bulk phases and defect structures.\nWe test the potential by applying it to the relaxation of point defects, core\nproperties of partial dislocations and the structure of disordered phases, none\nof which are included in the fitting procedure. For dislocations, our model\nmakes predictions in excellent agreement with ab initio and tight-binding\ncalculations. It is the only potential known to describe both the 30$^\\circ$-\nand 90$^\\circ$-partial dislocations in the glide set {111}. The structural and\nthermodynamic properties of the liquid and amorphous phases are also in good\nagreement with experimental and ab initio results. Our potential is the first\ncapable of simulating a quench directly from the liquid to the amorphous phase,\nand the resulting amorphous structure is more realistic than with existing\nempirical preparation methods. These advances in transferability come with no\nextra computational cost, since force evaluation with our model is faster than\nwith the popular potential of Stillinger-Weber, thus allowing reliable\natomistic simulations of very large atomic systems."
    },
    {
        "anchor": "Making the Dzyaloshinskii-Moriya interaction visible: Brillouin light spectroscopy is a powerful and robust technique for measuring\nthe interfacial Dzyaloshinskii-Moriya interaction in thin films with broken\ninversion symmetry. Here we show that the magnon visibility, i.e. the intensity\nof the inelastically scattered light, strongly depends on the thickness of the\ndielectric seed material - SiO$_2$. By using both, analytical thin-film optics\nand numerical calculations, we reproduce the experimental data. We therefore\nprovide a guideline for the maximization of the signal by adapting the\nsubstrate properties to the geometry of the measurement. Such a boost-up of the\nsignal eases the magnon visualization in ultrathin magnetic films, speeds-up\nthe measurement and increases the reliability of the data.",
        "positive": "First-Principles Modeling of Equilibration Dynamics of Hyperthermal\n  Products of Surface Reactions Using Scalable Neural Network Potential: Equilibration dynamics of hot oxygen atoms following O2 dissociation on\nPd(100) and Pd(111) surfaces are investigated by molecular dynamics simulations\nbased on a scalable neural network potential enabling first-principles\ndescription of O2 and O interacting with variable Pd supercells. We find that\nto accurately describe the equilibration dynamics after dissociation, the\nsimulation cell length necessarily exceeds twice the maximum distance of\nequilibrated oxygen adsorbates. By analyzing hundreds of trajectories with\nappropriate initial sampling, the measured distance distribution of\nequilibrated atom pairs on Pd(111) is well reproduced. However, our results on\nPd(100) suggest that the ballistic motion of hot atoms predicted previously is\na rare event under ideal conditions, while initial molecular orientation and\nsurface thermal fluctuation could significantly affect the overall\npost-dissociation dynamics. On both surfaces, dissociated oxygen atoms remain\nprimarily locate their nascent positions and then randomly cross bridge sites\nnearby."
    },
    {
        "anchor": "MD Simulations of Compression of Nanoscale Iron Pillars: It is now possible to create perfect crystal nanowires of many metals. The\ndeformation of such objects requires a good understanding of the processes\ninvolved in plasticity at the nanoscale. Isotropic compression of such\nnanometre scale micropillars is a good model system to understand the\nplasticity. Here we investigate these phenomena using Molecular Dynamics (MD)\nsimulations of nanometre scale single crystal BCC iron pillars in compression.\n  We find that pillars with large length to width ratio may buckle under high\nstrain rates. The type of buckling behaviour depends sensitively on the\nboundary conditions used: periodic boundary conditions allow for rotation at\ntop and bottom of the pillar, and result in an S shaped buckle, by contrast\nfixed boundaries enforce a C shape. Pillars with a length to width ratio closer\nto that used in experimental micropillar compression studies show deformation\nbehaviour dominated by slip, in agreement with the experiments. For\nmicropillars oriented along <100>, slip occurs on <110> planes and localized\nslip bands are formed. Pillars of this size experience higher stresses than\nbulk materials before yielding takes place. One might expect that this may be\nin part due to the lack of nucleation sites needed to induce slip. However,\nfurther simulations with possible dislocation sources: a shorter iron pillar\ncontaining a spherical grain boundary, and a similar pillar containing jagged\nedges did not show a decreased yield strength.",
        "positive": "Polar and phase domain walls with conducting interfacial states in a\n  Weyl semimetal MoTe2: Much of the dramatic growth in research on topological materials has focused\non topologically protected surface states. While the domain walls of\ntopological materials such as Weyl semimetals with broken inversion or\ntime-reversal symmetry can provide a hunting ground for exploring topological\ninterfacial states, such investigations have received little attention to date.\nHere, utilizing in-situ cryogenic transmission electron microscopy combined\nwith first-principles calculations, we discover intriguing domain-wall\nstructures in MoTe2, both between polar variants of the low-temperature(T) Weyl\nphase, and between this and the high-T high-order topological phase. We\ndemonstrate how polar domain walls can be manipulated with electron beams and\nshow that phase domain walls tend to form superlattice-like structures along\nthe c axis. Scanning tunneling microscopy indicates a possible signature of a\nconducting hinge state at phase domain walls. Our results open avenues for\ninvestigating topological interfacial states and unveiling multifunctional\naspects of domain walls in topological materials."
    },
    {
        "anchor": "Spin-lattice couplings in two-dimensional CrI$_3$ from first-principles\n  study: Since thermal fluctuations become more important as dimensions shrink, it is\nexpected that low-dimensional magnets are more sensitive to lattice distortions\nand phonons than bulk systems are. Here we present a fully relativistic\nfirst-principles study on the spin-lattice coupling, i.e. how the magnetic\ninteractions depend on local lattice distortions, of the prototypical\ntwo-dimensional ferromagnet CrI$_3$. We extract an effective measure of the\nspin-lattice coupling in CrI$_3$ which is up to ten times larger than what is\nfound for bcc Fe. The magnetic exchange interactions, including Heisenberg and\nrelativistic Dzyaloshinskii-Moriya interactions, are sensitive both to the\nin-plane motion of Cr atoms and out-of-plane motion of ligand atoms. We find\nthat significant magnetic pair interactions change sign from ferromagnetic (FM)\nto anti-ferromagnetic (AFM) for atomic displacements larger than 0.16 {\\AA}. We\nexplain the observed strong spin-lattice coupling by analyzing the orbital\ndecomposition of isotropic exchange interactions, involving different\ncrystal-field-split Cr$-3d$ orbitals. The competition between the AFM t$_{2g}$\n- t$_{2g}$ and FM t$_{2g}$ - e$_{g}$ contributions depends on the bond angle\nformed by Cr and I atoms as well as Cr-Cr distance. In particular, if a Cr atom\nis displaced, the FM-AFM sign change when the I-Cr-I bond angle approaches\n90$^\\circ$. The obtained spin-lattice coupling constants, along with the\nmicroscopic orbital analysis can act as a guiding principle for further studies\nof the thermodynamic properties and combined magnon-phonon excitations in\ntwo-dimensional magnets.",
        "positive": "Interface Engineering in La0.67Sr0.33MnO3-SrTiO3 Heterostructures: Interface engineering is an extremely useful tool for systematically\ninvestigating materials and the various ways materials interact with each\nother. We describe different interface engineering strategies designed to\nreveal the origin of the electric and magnetic dead-layer at La0.67Sr0.33MnO3\ninterfaces. La0.67Sr0.33MnO3 is a key example of a strongly correlated\nperoskite oxide material in which a subtle balance of competing interactions\ngives rise to a ferromagnetic metallic groundstate. This balance, however, is\neasily disrupted at interfaces. We systematically vary the dopant profile, the\ndisorder and the oxygen octahedra rotations at the interface to investigate\nwhich mechanism is responsible for the dead layer. We find that the magnetic\ndead layer can be completely eliminated by compositional interface engineering\nsuch that the polar discontinuity at the interface is removed. This, however,\nleaves the electrical dead-layer largely intact. We find that deformations in\nthe oxygen octahedra network at the interface are the dominant cause for the\nelectrical dead layer."
    },
    {
        "anchor": "Intrinsic degradation mechanism of nearly lattice-matched InAlN layers\n  grown on GaN substrates: Thanks to its high refractive index contrast, band gap and polarization\nmismatch compared to GaN, In0.17Al0.83N layers lattice-matched to GaN are an\nattractive solution for applications such as distributed Bragg reflectors,\nultraviolet light-emitting diodes, or high electron mobility transistors. In\norder to study the structural degradation mechanism of InAlN layers with\nincreasing thickness, we performed metalorganic vapor phase epitaxy of InAlN\nlayers of thicknesses ranging from 2 to 500 nm, on free-standing (0001) GaN\nsubstrates with a low density of threading dislocations, for In compositions of\n13.5% (layers under tensile strain), and 19.7% (layers under compressive\nstrain). In both cases, a surface morphology with hillocks is initially\nobserved, followed by the appearance of V-defects. We propose that those\nhillocks arise due to kinetic roughening, and that V-defects subsequently\nappear beyond a critical hillock size. It is seen that the critical thickness\nfor the appearance of V-defects increases together with the surface diffusion\nlength either by increasing the temperature or the In flux because of a\nsurfactant effect. In thick InAlN layers, a better (worse) In incorporation\noccurring on the concave (convex) shape surfaces of the V-defects is observed\nleading to a top phase-separated InAlN layer lying on the initial homogeneous\nInAlN layer after V-defects coalescence. It is suggested that similar\nmechanisms could be responsible for the degradation of thick InGaN layers.",
        "positive": "Electronic topological transition and non-collinear magnetism in\n  compressed hcp Co: Recent experiments showed that Co undergoes a phase transition from\nferromagnetic hcp phase to non-magnetic fcc one around 100 GPa. Since the\ntransition is of first order, a certain region of co-existence of the two\nphases is present. By means of \\textit{ab initio} calculations, we found that\nthe hcp phase itself undergoes a series of electronic topological transitions\n(ETTs), which affects both elastic and magnetic properties of the material.\nMost importantly, we propose that the sequence of ETTs lead to the\nstabilisation of a non-collinear spin arrangement in highly compressed hcp Co.\nDetails of this non-collinear magnetic state and the interatomic exchange\nparameters that are connected to it, are presented here."
    },
    {
        "anchor": "Propagation effects in high-harmonic generation from dielectric thin\n  films: Theoretical investigation is conducted of high-order harmonic generation\n(HHG) in silicon thin films to elucidate the effect of light propagation in\nreflected and transmitted waves. The first-principles simulations are performed\nof the process in which an intense pulsed light irradiates silicon thin films\nup to 3 $\\mu$m thickness. Our simulations are carried within the time-dependent\ndensity functional theory (TDDFT) with the account of coupled dynamics of the\nelectromagnetic fields and the electronic motion. It was found that the\nintensity of transmission HHG gradually decreases with the thickness, while the\nreflection HHG becomes constant from a certain thickness. Detailed analyses\nshow that transmission HHG have two origins: the HHG generated near the front\nedge and propagating to the back surface, and that generated near the back edge\nand emitted directly. The dominating mechanism of the transmission HHG is found\nto depend on the thickness of the thin film and the frequency of the HHG. At\nthe film thickness of 1 $\\mu$m, the transmission HHG with the frequency below\n20 eV is generated near the back edge, while that with the frequency above 20\neV is generated near the front edge and propagates from there to the back\nsurface.",
        "positive": "Machine-Learning Interatomic Potentials Enable First-Principles\n  Multiscale Modeling of Lattice Thermal Conductivity in Graphene/Borophene\n  Heterostructures: One of the ultimate goals of computational modeling in condensed matter is to\nbe able to accurately compute materials properties with minimal empirical\ninformation. First-principles approaches such as the density functional theory\n(DFT) provide the best possible accuracy on electronic properties but they are\nlimited to systems up to a few hundreds, or at most thousands of atoms. On the\nother hand, classical molecular dynamics (CMD) simulations and finite element\nmethod (FEM) are extensively employed to study larger and more realistic\nsystems, but conversely depend on empirical information. Here, we show that\nmachine-learning interatomic potentials (MLIPs) trained over short ab-initio\nmolecular dynamics trajectories enable first-principles multiscale modeling, in\nwhich DFT simulations can be hierarchically bridged to efficiently simulate\nmacroscopic structures. As a case study, we analyze the lattice thermal\nconductivity of coplanar graphene/borophene heterostructures, recently\nsynthesized experimentally (Sci. Adv. 2019; 5: eaax6444), for which no viable\nclassical modeling alternative is presently available. Our MLIP-based approach\ncan efficiently predict the lattice thermal conductivity of graphene and\nborophene pristine phases, the thermal conductance of complex\ngraphene/borophene interfaces and subsequently enable the study of effective\nthermal transport along the heterostructures at continuum level. This work\nhighlights that MLIPs can be effectively and conveniently employed to enable\nfirst-principles multiscale modeling via hierarchical employment of DFT/CMD/FEM\nsimulations, thus expanding the capability for computational design of novel\nnanostructures."
    },
    {
        "anchor": "Implantation and atomic scale investigation of self-interstitials in\n  graphene: Crystallographic defects play a key role in determining the properties of\ncrystalline materials. The new class of two-dimensional materials, foremost\ngraphene, have enabled atomically resolved studies of defects, such as\nvacancies, grain boundaries, dislocations, and foreign atom substitutions.\nHowever, atomic resolution imaging of implanted self-interstitials has so far\nnot been reported in any three- but also not in any two-dimensional material.\nHere, we deposit extra carbon into single-layer graphene at soft landing\nenergies of ~1 eV using a standard carbon coater. We identify all the\nself-interstitial dimer structures theoretically predicted earlier, employing\n80 kV aberration-corrected high-resolution transmission electron microscopy. We\ndemonstrate accumulation of the interstitials into larger aggregates and\ndislocation dipoles, which we predict to have strong local curvature by\natomistic modeling, and to be energetically favourable configurations as\ncompared to isolated interstitial dimers. Our results contribute to the basic\nknowledge on crystallographic defects, and lay out a pathway into engineering\nthe properties of graphene by pushing the crystal into a state of metastable\nsupersaturation.",
        "positive": "Strong single-ion anisotropy and anisotropic interactions of magnetic\n  adatoms induced by topological surface states: The nature of the magnetism brought about by Fe adatoms on the surface of the\ntopological insulator Bi2Se3 was examined in terms of density functional\ncalculations. The Fe adatoms exhibit strong easy-axis magnetic anisotropy in\nthe dilute adsorption limit due to the topological surface states (TSS). The\nspin exchange J between the Fe adatoms follows a Ruderman-Kittel-Kasuya-Yosida\n(RKKY) behavior with substantial anisotropy, and the Dzyaloshinskii-Moriya (DM)\ninteraction between them is quite strong with |D/J|~0.3 under the mediation by\nthe TSS, and can be further raised to ~0.6 by an external electric field. The\napparent single-ion anisotropy of a Fe adatom is indispensable in determining\nthe spin orientation."
    },
    {
        "anchor": "A General Charge Transport Picture for Organic Semiconductors with\n  Nonlocal Electron-Phonon Couplings: The nonlocal electron-phonon couplings in organic semiconductors responsible\nfor the fluctuation of intermolecular transfer integrals has been the center of\ninterest recently. Several irreconcilable scenarios coexist for the description\nof the nonlocal electron-phonon coupling, such as phonon-assisted transport,\ntransient localization, and band-like transport. Through a nearly exact\nnumerical study for the carrier mobility of the Holstein-Peierls model using\nthe matrix product states approach, we locate the phonon-assisted transport,\ntransient localization and band-like regimes as a function of the transfer\nintegral ($V$) and the nonlocal electron-phonon couplings ($\\Delta V$), and\ntheir distinct transport behaviors are analyzed by carrier mobility, mean free\npath, optical conductivity and one-particle spectral function. We also identify\nan \"intermediate regime\" where none of the established pictures applies, and\nthe generally perceived hopping regime is found to be at a very limited end in\nthe proposed regime paradigm.",
        "positive": "Realization of 2D Crystalline Metal Nitrides via Selective Atomic\n  Substitution: Two-dimensional (2D) transition metal nitrides (TMNs) are new members in the\n2D materials family with a wide range of applications. Particularly, highly\ncrystalline and large area thin films of TMNs are potentially promising for\napplications in electronic and optoelectronic devices; however, the synthesis\nof such TMNs has not yet been achieved. Here, we report the synthesis of\nfew-nanometer thin Mo5N6 crystals with large area and high quality via in situ\nchemical conversion of layered MoS2 crystals. The structure and quality of the\nultrathin Mo5N6 crystal are confirmed using transmission electron microscopy,\nRaman spectroscopy and X-ray photoelectron spectroscopy. The large lateral\ndimensions of Mo5N6 crystals are inherited from the MoS2 crystals that are used\nfor the conversion. Atomic force microscopy characterization reveals the\nthickness of Mo5N6 crystals is reduced to about 1/3 of the MoS2 crystal.\nElectrical measurements show the obtained Mo5N6 samples are metallic with high\nelectrical conductivity (~ 100 {\\Omega} sq-1), which is comparable to graphene.\nThe versatility of this general approach is demonstrated by expanding the\nmethod to synthesize W5N6 and TiN. Our strategy offers a new direction for\npreparing 2D TMNs with desirable characteristics, opening a door for studying\nfundamental physics and facilitating the development of next generation\nelectronics."
    },
    {
        "anchor": "Crystal Graph Convolutional Neural Networks for an Accurate and\n  Interpretable Prediction of Material Properties: The use of machine learning methods for accelerating the design of\ncrystalline materials usually requires manually constructed feature vectors or\ncomplex transformation of atom coordinates to input the crystal structure,\nwhich either constrains the model to certain crystal types or makes it\ndifficult to provide chemical insights. Here, we develop a crystal graph\nconvolutional neural networks framework to directly learn material properties\nfrom the connection of atoms in the crystal, providing a universal and\ninterpretable representation of crystalline materials. Our method provides a\nhighly accurate prediction of density functional theory calculated properties\nfor eight different properties of crystals with various structure types and\ncompositions after being trained with $10^4$ data points. Further, our\nframework is interpretable because one can extract the contributions from local\nchemical environments to global properties. Using an example of perovskites, we\nshow how this information can be utilized to discover empirical rules for\nmaterials design.",
        "positive": "Selective Area Growth Rates of III-V Nanowires: Selective area growth (SAG) of semiconductors is a scalable method for\nfabricating gate-controlled quantum platforms. This letter reports on the\nadatom diffusion, incorporation, and desorption mechanisms that govern the\ngrowth rates of SAG nanowire (NW) arrays. We propose a model for the crystal\ngrowth rates that considers two parameter groups: the crystal growth control\nparameters and the design parameters. Using GaAs and InGaAs SAG NWs as platform\nwe show how the design parameters such as NW pitch, width, and orientation have\nan impact on the growth rates. We demonstrate that by varying the control\nparameters (i.e. substrate temperature and beam fluxes) source, balance, and\nsink growth modes may exist in the SAG selectivity window. Using this model, we\nshow that inhomogeneous growth rates can be compensated by tuning the design\nparameters."
    },
    {
        "anchor": "Phonon Coherent Resonance and Its Effect on Thermal Transport In\n  Core-Shell Nanowires: We study heat current autocorrelation function and thermal conductivity in\ncore-shell nanowires by using molecular dynamics simulations. Interestingly, a\nremarkable oscillation effect in heat current autocorrelation function is\nobserved in core-shell NWs, while the same effect is absent in pure silicon\nnanowires, nanotube structures and random doped nanowires. Detailed\ncharacterizations of the oscillation signal reveal that this intriguing\noscillation is caused by the coherent resonance effect of the transverse and\nlongitudinal phonon modes. This phonon resonance results in the localization of\nthe longitudinal modes, which leads to the reduction of thermal conductivity in\ncore-shell nanowires. Our study reveals that a coherent mechanism can be used\nto tune thermal conductivity in core-shell nanowires.",
        "positive": "Inelastic neutron scattering studies of YFeO$_3$: Spin waves in the the rare earth orthorferrite YFeO$_3$ have been studied by\ninelastic neutron scattering and analyzed with a full four-sublattice model\nincluding contributions from both the weak ferromagnetic and hidden\nantiferromagnetic orders. Antiferromagnetic (AFM) exchange interactions of $J_1\n= -4.23 \\pm 0.08$ (nearest-neighbors only) or $J_1 = -4.77 \\pm 0.08$ meV and\n$J_2 = -0.21 \\pm 0.04$ meV lead to excellent fits for most branches at both low\nand high energies. An additional branch associated with the hidden\nantiferromagnetic order was observed. This work paves the way for studies of\nother materials in this class containing spin reorientation transitions and\nmagnetic rare earth ions."
    },
    {
        "anchor": "Organometallic Wires Constructed from Transitional Metals and\n  Anthracene: A Theoretical Study: The properties of organometallic wires [TM2(Ant)] constructed with\ntransitional metals (TM = Sc, Ti, V, Cr, Mn and Fe) and anthracene (Ant) are\ninvestigated by first-principles calculations. As the gap between HOMO (Highest\nOccupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital) of\nAnt is much smaller than that of benzene (Bz), much larger charge transfer (CT)\noccurs between TMs and Ant, which results in much more diverse magnetic\nproperties in [TM2(Ant)] than in [TM2(Ant)]. Particularly, [V2(Ant)] and\n[Cr2(Ant)] are found to be half-metallic ferromagnets. As a result of this and\nthe better structural stability, compared with [TM(Bz)], [TM2(Ant)] (like\n[V2(Ant)] and [Cr2(Ant)]) may be better candidates of spintronic devices.\nFurthermore, as the HOMO-LUMO gap of small pieces of graphene (SPG), such as\npentacene and coronene, decreases with the increase of polycyclic number, the\nCT effects may also fit for the TM-SPG sandwich polymers which can also act as\ngood spintronic materials.",
        "positive": "The complete micromagnetic characterization of asymmetrically sandwiched\n  ferromagnetic films: The magnetic properties of ferromagnetic thin films down to the nanoscale are\nruled by the exchange stiffness, anisotropies and the effects of magnetic\nfields. As surfaces break inversion symmetry, an additional effective chiral\nexchange is omnipresent in any magnetic nanostructure. These so-called\nDzyaloshinskii-Moriya interactions (DMI) affect all inhomogeneous magnetic\nstates either subtly or spectacularly. E.g., DMIs cause a chirality selection\nof the rotation sense and can fix the local rotation axis for the magnetization\nin domain walls (DW). But, they can stabilize also entirely different twisted\nmagnetic structures. The chiral skyrmions a two-dimensional particle-like\ntopological soliton is the ultimately smallest of these objects, which\ncurrently is targetted as a possible information carrier in novel spintronic\ndevices. Observation and quantification of the chiral exchange effects provide\nfor the salient point in understanding magnetic properties in ultrathin films\nand other nanostructures. An easy and reliable method to determine the DMI\nconstant as materials parameter of asymmetric thin films is the crucial\nproblem. Here, we put forth an experimental approach for the determination of\nthe complete set of the micromagnetic parameters. Quasi-static Kerr microcopy\nobservations of DW creep motion and equilibrium sizes of circular magnetic\nobjects in combination with standard magnetometry are used to derive a\nconsistent set of these materials parameters in polycrystalline ultrathin film\nsystems, namely CrOx/Co/Pt stacks. The quantified micromagnetic model for these\nfilms identifies the circular magnetic objects, as seen by the optical\nmicroscopy, as ordinary bubble domains with homochiral walls. From\nmicromagnetic calculations, the chiral skyrmions stabilized by the DMI in these\nfilms are shown to have diameters in the range 40-200nm, too small to be\nobserved by optical microscopy."
    },
    {
        "anchor": "Probing the A1 to L10 Transformation in FeCuPt Using the First Order\n  Reversal Curve Method: The A1- L10 phase transformation has been investigated in (001) FeCuPt thin\nfilms prepared by atomic-scale multilayer sputtering and rapid thermal\nannealing (RTA). Traditional x-ray diffraction is not always applicable in\ngenerating a true order parameter, due to non-ideal crystallinity of the A1\nphase. Using the first-order reversal curve (FORC) method, the A1 and L10\nphases are deconvoluted into two distinct features in the FORC distribution,\nwhose relative intensities change with the RTA temperature. The L10 ordering\ntakes place via a nucleation-and-growth mode. A magnetization-based phase\nfraction is extracted, providing a quantitative measure of the L10 phase\nhomogeneity.",
        "positive": "Spin-signal propagation in time-dependent noncollinear spin transport: Using a macroscopic analysis, we show that time-dependent noncollinear spin\ntransport possesses a wavelike character. This leads to modifications of pure\nspin-diffusion dynamics and allows one to extract a finite spin-signal\npropagation velocity. We numerically study the dynamics of a pure spin current\npumped into a nonmagnetic layer for precession frequencies ranging from GHz to\nTHz."
    },
    {
        "anchor": "Defect engineering over anisotropic brookite towards substrate-specific\n  photo-oxidation of alcohols: Generally adopted design strategies for enhancing the photocatalytic activity\nare aimed at tuning properties such as the visible light response, the exposed\ncrystal facets, and the nanocrystal shape. Here, we present a different\napproach for designing efficient photocatalysts displaying a substrate-specific\nreactivity upon defect engineering. The defective anisotropic brookite TiO2\nphotocatalyst functionalized with Pt nanocrystals are tested for alcohol\nphotoreforming showing up to an 11-fold increase in methanol oxidation rate,\ncompared to the unreduced one, whilst presenting much lower ethanol or\nisopropanol specific oxidation rates. We demonstrate that the alcohol oxidation\nand hydrogen evolution reactions are tightly related, and when the\nsubstrate-specific alcohol oxidation ability is increased, the hydrogen\nevolution is significantly boosted. The reduced anisotropic brookite shows up\nto twenty-six-fold higher specific photoactivity with respect to anatase and\nbrookite with isotropic nanocrystals, reflecting the different type of\ndefective catalytic sites formed depending on the TiO2 polymorph and its\ncrystal shape. Advanced in-situ characterizations and theoretical\ninvestigations reveal that controlled engineering over oxygen vacancies and\nlattice strain produces large electron polarons hosting the substrate-specific\nactive sites for alcohol photo-oxidation.",
        "positive": "Revealing the formation and electrochemical properties of\n  bis(trifluoromethanesulfonyl) imide intercalated graphite with\n  first-principles calculations: Graphite has been reported to have anion as well as cation intercalation\ncapacities as both cathode and anode host materials for the dual ion battery.\nIn this work, we study the intercalation of bis(trifluoromethanesulfonyl) imide\n(TFSI) anion from ionic liquid electrolyte into graphite with first-principles\ncalculations. We build models for TFSI-C$_n$ compounds with systematically\nincreasing unit cell sizes of graphene sheet and investigate their stabilities\nby calculating the formation energy, resulting in the linear decrease and\narriving at the limit of stability. With identified unit cell sizes for stable\ncompound formation, we reveal that the interlayer distance and relative volume\nexpansion ratio of TFSI-C$_n$ increase as increasing the concentration of TFSI\nintercalate during the charge process. The electrode voltage is determined to\nbe ranged from 3.8 V to 3.0 V at the specific capacity ranging from 30 mAh\ng$^{-1}$ to 54 mAh g$^{-1}$ in agreement with experiment. Moreover, a very low\nactivation barrier of under 50 meV for TFSI migration and good electronic\nconductivity give a proof of using these compounds as a promising cathode.\nThrough the analysis of charge transfer, we clarify the mechanism of TFSI-C$_n$\nformation, and reveal new prospects for developing graphite based cathode."
    },
    {
        "anchor": "On a certain analogy between hydrodynamic flow in porous media and heat\n  conductance in solids: We consider a porous medium being saturated with a pore fluid (Biot's\ntheory). The fluid is assumed as incompressible. It is shown that the general\nintegral of the elastic and pressure equations can be written in form of a time\ndependent vectorpotential ${\\bf F}$ being a solution of a homogeneous, fourth\norder differential equation. The obtained equation for ${\\bf F}$ is of a more\ngeneral form than the corresponding thermo-elastic vectorpotential, being a\nsolution of a time dependent and inhomogeneous vector bi-Laplacian. Both\nvectorpotentials do, however, agree for stationary problems in general and for\ncertain particular boundary conditions (irrotational deformations). An example\nof an irrotational deformation is studied in detail, exhibiting known\nproperties of classical vector diffusion",
        "positive": "On the Strength of the Carbon Nanotube-Based Space Elevator Cable: From\n  Nano- to Mega-Mechanics: In this paper different deterministic and statistical models, based on new\nquantized theories proposed by the author, are presented to estimate the\nstrength of a real, thus defective, space elevator cable. The cable, of ~100\nmegameters in length, is composed by carbon nanotubes, ~100 nanometers long:\nthus, its design involves from the nano- to the mega-mechanics. The predicted\nstrengths are extensively compared with the experiments and the atomistic\nsimulations on carbon nanotubes available in the literature. All these\napproaches unequivocally suggest that the megacable strength will be reduced by\na factor at least of ~70% with respect to the theoretical nanotube strength,\ntoday (erroneously) assumed in the cable design. The reason is the unavoidable\npresence of defects in a so huge cable. Preliminary in silicon tensile\nexperiments confirm the same finding. The deduced strength reduction is\nsufficient to pose in doubt the effective realization of the space elevator,\nthat if built as today designed will surely break (according to the s opinion).\nThe mechanics of the cable is also revised and possibly damage sources\ndiscussed."
    },
    {
        "anchor": "Unexpected Reconstruction of the alpha-Boron (111) Surface: We report on a novel reconstruction of the alpha-boron (111) surface,\ndiscovered using an ab initio evolution structure search, and reveal that it\nhas an unexpected neat structure and much lower surface energy than the\nrecently proposed (111)-I_R,(a) surface. For this reconstruction, every single\ninterstitial boron atom forms bridges with the unique polar-covalent bonds\nbetween neighboring B_12 icosahedra, which perfectly meet the electron counting\nrule and are responsible for the reconstruction-induced metal-semiconductor\ntransition. The peculiar charge transfer between the interstitial atoms and the\nicosahedra plays an important role in stabilizing the surface.",
        "positive": "Extraction of Linear Carbon Chains Unravels the Role of the Carbon\n  Nanotube Host: Linear carbon chains (LCCs) have been shown to grow inside double-walled\ncarbon nanotubes (DWCNTs) but isolating them from this hosting material\nrepresents one of the most challenging tasks towards applications. Herein we\nreport the extraction and separation of LCCs inside single-wall carbon\nnanotubes (LCCs@SWCNTs) extracted from a double walled host LCCs@DWCNTs by\napplying a combined tip-ultrasonic and density gradient ultracentrifugation\n(DGU) process. High-resolution transmission electron microscopy (HRTEM),\noptical absorption, and Raman spectroscopy show that not only short LCCs but\nclearly long LCCs (LLCCs) can be extracted and separated from the host.\nMoreover, the LLCCs can even be condensed by DGU. The Raman spectral frequency\nof LCCs remains almost unchanged regardless of the presence of the outer tube\nof the DWCNTs. This suggests that the major importance of the outer tubes is\nmaking the whole synthesis viable. We have also been able to observe the\ninteraction between the LCCs and the inner tubes of DWCNTs, playing a major\nrole in modifying the optical properties of LCCs. Our extraction method\nsuggests the possibility towards the complete isolation of LCCs from CNTs."
    },
    {
        "anchor": "TiS3 transistors with tailored morphology and electrical properties: Control over the morphology of TiS3 is demonstrated by synthesizing 1D\nnanoribbons and 2D nanosheets. The nanosheets can be exfoliated down to a\nsingle layer. Through extensive characterization of the two morphologies,\ndifferences in the electronic properties are found and attributed to a higher\ndensity of sulphur vacancies in nanosheets which, according to density\nfunctional theory calculations, leads to an n-type doping.",
        "positive": "Unravelling brittle fracture statistics out of self-healing patterns\n  forming during femtosecond laser exposure: Femtosecond laser written patterns at the surface of brittle materials may\nshow a regenerative random transition from self-organized to disordered\nstructures. Here, we show that this random intermittent behaviour carries\nrelevant fracture statistics information, such as the so-called Weibull\nparameters. Furthermore, we draw a phenomenological analogy with idle and busy\nperiods arising in queueing systems that we used to establish that these\nsuccessive laser generated cycles are statistically independent. Based on this\nanalogy and together with microscopic observations, we propose an experimental\nmethod bypassing the need for many specimens to build-up statistically relevant\nensembles of fracture tests. This method is potentially generic as it may apply\nto a broad number of brittle materials."
    },
    {
        "anchor": "Strain and voltage control of magnetic and electric properties of FeRh\n  films: FeRh based alloys may display an uncommon transition from a ferromagnetic to\nan antiferromagnetic state upon cooling. The transition takes place roughly\nabove room temperature and it can be sensitively modulated by composition and\nexternal parameters, including pressure and strain. Consequently, thin films of\nFeRh have received attention for applications in spintronics, antiferromagnetic\nspintronics and sensing. Interestingly, the extreme sensitivity of its\nproperties to strain has created expectations for energy friendly\nvoltage-control of the magnetic state of FeRh, with a number of potential\napplications at the horizon. Here, after summarizing the current understanding\nof strain effects on the magnetic properties of FeRh thin films, we review\nachievements on exploiting piezoelectric substrates for in-operando tuning of\ntheir magneto-electric properties. We end with a brief summary and an outlook\nfor future initiatives.",
        "positive": "Instability of the ferrofluid layer on a magnetizable substrate in a\n  perpendicular magnetic field: The paper presents an experimental study of the instability of a magnetic\nfluid layer of finite thickness covering a magnetizable metal plate exposed to\na perpendicular magnetic field. The critical field strength and the instability\nwave number have been measured."
    },
    {
        "anchor": "MoS2 Impurities: Chemical Identification and Spatial Resolution of\n  Bismuth Impurities in Geological Material: Molybdenum disulfide (MoS2) is the most widely studied transition metal\ndichalcogenide (TMDC) material, in part because it is a natural crystal present\nin the earth, thus making it abundant and easily accessible. Geological MoS2\nhas been used in various studies that look at incorporating MoS2 into devices\nfor nanoelectronics and optoelectronics. However, variations in the electronic\nproperties of a single MoS2 surface are known to exist due to defects that are\nintrinsic to natural MoS2. This work reports the presence of bismuth impurities\nin MoS2 with concentrations high enough to be detected by X-ray photoelectron\nspectroscopy (XPS). These concentrations are further corroborated with\ninductively coupled plasma optical emission spectroscopy (ICP-OES).\nLocalization of these bismuth clusters is shown using XPS-mapping, and the\ncluster size is determined to be on the order of tens of microns. This work\nprovides important insights into the nature of impurities that are known to\nexist in MoS2.",
        "positive": "Cube-shape diffuse scattering and the ground state of\n  $\\mathrm{BaMg}_{1/3}\\mathrm{Ta}_{2/3} \\mathrm{O}_3$: A quite unusual diffuse scattering phenomenology was observed in the\nsingle-crystal X-ray diffraction pattern of cubic perovskite BMT\n($\\mathrm{BaMg}_{1/3}\\mathrm{Ta}_{2/3}\\mathrm{O}_3$). The intensity of the\nscattering is parametrized as a set of cube-like objects located at the centers\nof reciprocal space unit cells, resembling very broad and cubic-shaped\n(1/2,1/2,1/2)-satellites. BMT belongs to perovskites of formula\nAB$'_{1/3}$B$\"_{2/3}$O$_{3}$ (A=Mg, B$'=$Ta, B$\"=$Mg). The cubes of the\nintensity can be attributed to the partial correlations of the occupancies of\nthe B site. The pair correlation function is the Fourier transform of the\ndiffuse scattering intensity and the latter's idealized form yields the unusual\nproperty of a power-law correlation decay with distance. Up to now this is\nobserved only in a few exotic instances of magnetic order or nematic crystals.\nTherefore it cannot be classified as a short-range order phenomenon, as in most\nsituations originating diffuse scattering. A Monte-Carlo search in\nconfiguration space yielded solutions that reproduce faithfully the observed\ndiffuse scattering. Analysis of the results in terms of the electrostatic\nenergy and the entropy point to this phase of BMT as a metastable state,\nkinetically locked, which could be the equilibrium state just below the melting\npoint."
    },
    {
        "anchor": "A new migration mechanism for oversized solutes in cubic lattices:\n  correlation effects: Recent ab-initio calculations showed that oversized solute atoms (OSA) in BCC\nand FCC iron exhibit a very strong attraction with a nearby vacancy (V) at\nfirst neighbour distance (1NN). The attraction it is so large that the 1NN pair\nOSA+V is no longer stable and relaxes spontaneously towards a new configuration\nwhere the OSA sits in the middle of the bond, the two ends of which are\ndecorated with two half-vacancies (V/2). Taking into account the formation of\nthis complex V/2+OSA+V/2 in the migration process has never been done before:\nit requires a new formulation of correlation effects. This is the aim of the\npresent contribution which establishes the expression of the diffusion\ncoefficient of the OSA and evaluates exactly the correlation factor in BCC and\nFCC lattices, thanks to the introduction of macrojumps. The formalism is\napplied to the case of Y in BCC iron and its results are compared to those\nobtained by previous authors. It is shown that the smallness of the correlation\nfactor is not due to the transport mechanism of the OSA but only to the jump\nfrequencies of the vacancy in the vicinity of the OSA. This smallness of the\ncorrelation factor is however overcompensated by a large macrojump frequency,\nand, as a result, the Y atom diffuses more rapidly than iron at all\ntemperatures by orders of magnitude in the two structures.",
        "positive": "Dislocation Kinks in Copper: Widths, Barriers, Effective Masses, and\n  Quantum Tunneling: We calculate the widths, migration barriers, effective masses, and quantum\ntunneling rates of kinks and jogs in extended screw dislocations in copper,\nusing an effective medium theory interatomic potential. The energy barriers and\neffective masses for moving a unit jog one lattice constant are close to\ntypical atomic energies and masses: tunneling will be rare. The energy barriers\nand effective masses for the motion of kinks are unexpectedly small due to the\nspreading of the kinks over a large number of atoms. The effective masses of\nthe kinks are so small that quantum fluctuations will be important. We discuss\nimplications for quantum creep, kink--based tunneling centers, and Kondo\nresonances."
    },
    {
        "anchor": "Unforeseen high temperature and humidity stability of FeCl$_3$\n  intercalated few layer graphene: We present the first systematic study of the stability of the structure and\nelectrical properties of FeCl$_3$ intercalated few-layer graphene to high\nlevels of humidity and high temperature. Complementary experimental techniques\nsuch as electrical transport, high resolution transmission electron microscopy\nand Raman spectroscopy conclusively demonstrate the unforeseen stability of\nthis transparent conductor to a relative humidity up to $100 \\%$ at room\ntemperature for 25 days, to a temperature up to $150\\,^\\circ$C in atmosphere\nand up to a temperature as high as $620\\,^\\circ$C in vacuum, that is more than\ntwice higher than the temperature at which the intercalation is conducted. The\nstability of FeCl$_3$ intercalated few-layer graphene together with its unique\nvalues of low square resistance and high optical transparency, makes this\nmaterial an attractive transparent conductor in future flexible electronic\napplications.",
        "positive": "Frozen local hole approximation: The frozen local hole approximation (FLHA) is an adiabatic approximation\nwhich is aimed to simplify the correlation calculations of valence and\nconduction bands of solids and polymers. Within this approximation correlated\nlocal hole states (CLHSs) are explicitely generated by correlating local\nHartree-Fock (HF) hole states. The hole orbital and its occupancy is kept\nfrozen during these correlation calculations. Effective Hamilton matrix\nelements are then evaluated with the above CLHSs; diagonalization finally\nyields the desired correlation corrections for the cationic hole states. We\ncompare and analyze the results of the FLHA with the results of a full MRCI(SD)\n(multi-reference configuration interaction with single and double excitations)\ncalculation for two prototype model systems, (H2)n ladders and H-(Be)n-H\nchains. Excellent numerical agreement between the two approaches is found.\nComparing the FLHA with a full correlation treatment in the framework of\nquasi-degenerate variational perturbation theory reveals that the leading\ncontributions in the two approaches are identical. Thus, the FLHA is\nwell-justified and provides a very promising and efficient alternative to fully\ncorrelated wavefunction-based treatments of the valence and conduction bands in\nextended systems."
    },
    {
        "anchor": "Substitutional Doped GeSe: Tunable Oxidative States with Strain\n  Engineering: Layered chalcogenide materials have a wealth of nanoelectronics applications\nlike resistive switching and energy-harvesting such as photocatalyst owing to\nrich electronic, orbital, and lattice excitations. In this work, we explore\nmonochalcogenide germanium selenide GeSe with respect to substitutional doping\nwith 13 metallic cations by using first-principles calculations. Typical\ndopants including s-shell (alkali elements Li and Na), p-shell (Al, Pb and Bi),\n3d (Fe, Cu, Co and Ni), 4d (Pd and Ag) and 5d (Au and Pt) elements are\nsystematically examined. Amongst all the cationic dopants, Al with the highest\noxidation states, implying a high mobility driven by electric field, and\nAl-doped GeSe may be a promising candidate for novel resistive switching\ndevices. We show that there exist many localized induced states in the band gap\nof GeSe upon doping Fe, Co, or Ni, while for Cu, Ag, and Au cases there is no\nsuch states in the gap. The Ag and Cu are + 0.27 and + 0.35 charged\nrespectively and the positive charges are beneficial for field-driven motion in\nGeSe. In contrast, Au is slightly negatively charged renders Au-doped GeSe a\npromising photocatalyst and enhanced surface plasmon. Moreover, we explore the\ncoexistence of dopant and strain in GeSe and find dynamical adjustments of\nlocalized states in GeSe with levels successive shifting upward/downward with\nstrain. This induces dynamic oxidative states of the dopants under strain which\nshould be quite popular in composites where motion of metal adatoms causes\nsignificant deformation.",
        "positive": "Two-dimensional honeycomb borophene oxide: Strong anisotropy and nodal\n  loop transformation: The search for topological semimetals is mainly focused on heavy-element\ncompounds as following the footsteps of previous research on topological\ninsulators, with less attention on light-element materials. However, the\nnegligible spin orbit coupling with light elements may turn out to be\nbeneficial for realizing topological band features.Here, using first-principles\ncalculations, we propose a new two-dimensional light-element material-the\nhoneycomb borophene oxide (h-B2O), which has nontrivial topological\nproperties.The proposed structure is based on the recently synthesized\nhoneycomb borophene on Al (111) substrate [Sci. Bull. 63, 282 (2018)]. The\nh-B2O monolayer is completely flat, unlike the oxides of graphene or silicene.\nWe systematically investigate the structural properties of h-B2O, and find that\nit has very good stability and exhibits significant mechanical anisotropy.\nInterestingly, the electronic band structure of h-B2O hosts a nodal loop\ncentered around the Y point in the Brillouin zone, protected by the mirror\nsymmetry. Furthermore, under moderate lattice strain, the single nodal loop can\nbe transformed into two loops, each penetrating through the Brillouin zone. The\nloops before and after the transition are characterized by different Z*Z\ntopological indices. Our work not only predicts a new two-dimensional material\nwith interesting physical properties, but also offers an alternative approach\nto search for new topological phases in 2D light-element systems."
    },
    {
        "anchor": "Contacting individual Fe(110) dots in a single electron-beam lithography\n  step: We report on a new approach, entirely based on electron-beam lithography\ntechnique, to contact electrically, in a four-probe scheme, single\nnanostructures obtained by self-assembly. In our procedure, nanostructures of\ninterest are localised and contacted in the same fabrication step. This\ntechnique has been developed to study the field-induced reversal of an internal\ncomponent of an asymmetric Bloch domain wall observed in elongated structures\nsuch as Fe(110) dots. We have focused on the control, using an external\nmagnetic field, of the magnetisation orientation within N\\'eel caps that\nterminate the domain wall at both interfaces. Preliminary magneto-transport\nmeasurements are discussed demonstrating that single Fe(110) dots have been\ncontacted.",
        "positive": "Persistent Current in Two Coupled Rings: We report the solution of the persistent current in two coupled rings in the\npresence of external magnetic fluxes. We showed that the magnetic fluxes modify\nthe global phase of the electronic wave function for multiple connected\ngeometry formed by the coupled rings. We obtained an exact solution for the\npersistent current and investigated the exact solution numerically. For two\nlarge coupled rings with equal fluxes, we found that the persistent current in\nthe two coupled rings is in fact equal to that in a single ring. This theory\nexplains the experimental results observed in a line of sixteen coupled rings.\n(Phys. Rev. Lett. 86, 3124 (2001).)"
    },
    {
        "anchor": "Binding energies and spatial structures of small carrier complexes in\n  monolayer transition metal dichalcogenides via diffusion Monte Carlo: Ground state diffusion Monte Carlo is used to investigate the binding\nenergies and carrier probability distributions of excitons, trions, and\nbiexcitons in a variety of two-dimensional transition metal dichalcogenide\nmaterials. We compare these results to approximate variational calculations, as\nwell as to analogous Monte Carlo calculations performed with simplified carrier\ninteraction potentials. Our results highlight the successes and failures of\napproximate approaches as well as the physical features that determine the\nstability of small carrier complexes in monolayer transition metal\ndichalcogenide materials. Lastly, we discuss points of agreement and\ndisagreement with recent experiments.",
        "positive": "Deposition of thin silicon layers on transferred large area CVD graphene: Physical vapor deposition of Si onto transferred graphene is investigated. At\nelevated temperatures, Si nucleates preferably on wrinkles and multilayer\ngraphene islands. In some cases, however, Si can be quasi-selectively grown\nonly on the monolayer graphene regions while the multilayer islands remain\nuncovered. Experimental insights and ab initio calculations show that\nvariations in the removal efficiency of carbon residuals after the transfer\nprocess can be responsible for this behavior. Low-temperature Si seed layer\nresults in improved wetting and enables homogeneous growth. This is an\nimportant step towards realization of electronic devices in which graphene is\nembedded between two Si layers."
    },
    {
        "anchor": "Clusters of interstitial carbon atoms near the graphite surface as a\n  possible origin of dome-like features observed by STM: Formation of clusters of interstitial carbon atoms between the surface and\nsecond atomic layers of graphite is demonstrated by means of molecular dynamics\nsimulations. It is shown that interstitial clusters result in the dome-like\nsurface features that may be associated with some of the hillocks observed by\nSTM on the irradiated graphite surface.",
        "positive": "Structural and dielectric characterization of Sm2MgMnO6: The polycrystalline Sm2MgMnO6 (SMMO) was synthesized at 1173K by means of\nsol-gel technique. Rietveld refine-ment of X-ray diffraction (XRD) pattern\nconfirmed the formation of a single phase monoclinic structure with space group\nP21/n. The band gap achieved from UV-vis spectra shows the semiconducting\nnature of the material. To observe the effect of grains and grain-boundaries in\nthe conduction process and dielectric relaxation measurements are carried out\non SMMO sample at different frequencies between 313 K and 673 K. An electrical\nequivalent circuit consisting of the resistance and constant phase element is\nused to clarify the impedance data."
    },
    {
        "anchor": "Perovskite solar cells at radiative detailed balance limit: Here, we report the first experimental demonstration of perovskite solar\ncells at radiative detailed balance limit. To conclusively establish this\nclaim, we theoretically identified a set of quantitative benchmark\ncharacteristics expected from solar cells at radiative detailed balance limits.\nTransient as well as steady state intensity dependent measurements indicate\nthat our solar cells are indeed operating at such limits with interface\npassivation comparable to the champion c-Si technology. Remarkably, our\nanalysis also facilitates novel characterization schemes which enable\nconsistent back extraction of important recombination parameters from\nopto-electrical measurements. These results have significant implications\ntowards fundamental electronic processes in perovskite solar cells and further\nefficiency optimization towards Shockeley-Queisser limits.",
        "positive": "Fingering Instability of Dislocations and Related Defects: We identify a fundamental morphological instability of mobile dislocations in\ncrystals and related line defects. A positive gradient in the local driving\nforce along the direction of defect motion destabilizes long-wavelength\nvibrational modes, producing a ``fingering'' pattern. The minimum unstable\nwavelength scales as the inverse square root of the force gradient. We\ndemonstrate the instability's onset in simulations of a screw dislocation in Al\n(via molecular dynamics) and of a vortex in a 3-d XY ``rotator'' model."
    },
    {
        "anchor": "Comment on \"Compositional and Microchemical Evidence of Piezonuclear\n  Fission Reactions in Rock Specimens Subjected to Compression Tests\" [Strain\n  47 (Suppl. 2), 282 (2011)]: It is shown that the chemical composition data published by Carpinteri et al.\nin the article \"Compositional and Microchemical Evidence of Piezonuclear\nFission Reactions in Rock Specimens Subjected to Compression Tests\" [Strain 47\n(Suppl. 2), 282 (2011)] cannot be the result of independent measurements as\nclaimed by the authors. Therefore, no conclusion can be drawn from them about\ncompositional modifications induced in the stone by hypothetical piezonuclear\nreactions taking place during catastrophic failure of the material at fracture.",
        "positive": "Quantum corrected Langevin dynamics for adsorbates on metal surfaces\n  interacting with hot electrons: We investigate the importance of including quantized initial conditions in\nLangevin dynamics for adsorbates interacting with a thermal reservoir of\nelectrons. For quadratic potentials the time evolution is exactly described by\na classical Langevin equation and it is shown how to rigorously obtain quantum\nmechanical probabilities from the classical phase space distributions resulting\nfrom the dynamics. At short time scales, classical and quasiclassical initial\nconditions lead to wrong results and only correctly quantized initial\nconditions give a close agreement with an inherently quantum mechanical master\nequation approach. With CO on Cu(100) as an example, we demonstrate the effect\nfor a system with ab initio frictional tensor and potential energy surfaces and\nshow that quantizing the initial conditions can have a large impact on both the\ndesorption probability and the distribution of molecular vibrational states."
    },
    {
        "anchor": "Cation spin and superexchange interaction in oxide materials below and\n  above spin crossover under high pressure: We derived simple rules for the sign of superexchange interaction based on\nthe multielectron calculations of the superexchange interaction in the\ntransition metal oxides that are valid both below and above spin crossover\nunder high pressure. The superexchange interaction between two cations in d$^n$\nconfigurations is given by a sum of individual contributions related to the\nelectron-hole virtual excitations to the different states of the d$^{n + 1}$\nand d$^{n - 1}$ configurations. Using these rules, we have analyzed the sign of\nthe superexchange interaction of a number of oxides with magnetic cations in\nelectron configurations from d$^2$ till d$^8$: the iron, cobalt, chromium,\nnickel, copper and manganese oxides with increasing pressure. The most\ninteresting result concerns the magnetic state of cobalt and nickel oxides CoO,\nNi$_2$O$_3$ and also La$_2$CoO$_4$, LaNiO$_3$ isostructural to well-known\nhigh-T$_C$ and colossal magnetoresistance materials. These oxides have a spin\n$\\frac{1}{2}$ at the high pressure. Change of the interaction from\nantiferromagnetic below spin crossover to ferromagnetic above spin crossover is\npredicted for oxide materials with cations in d$^5$(FeBO$_3$) and d$^7$(CoO)\nconfigurations, while for materials with the other d$^n$ configurations spin\ncrossover under high pressure does not change the sign of the superexchange\ninteraction.",
        "positive": "Linear Algebra and Charge Self-consistent Tight-binding Method for\n  Large-scale Electronic Structure Calculations: We review our recently developed electronic structure calculation methods\nused for the dynamics of large-scale solids or liquids with an efficient\nalgorithm for large scale simultaneous linear equations. The electronic\nstructure calculation method is the `atomic superposition and electron\ndelocalization molecular orbitals theory' (ASED), using the Mulliken charge\ndensity. Very crucial algorithm is the generalized shifted COCG (conjugate\northogonal conjugate gradient) method based on the Krylov subspace extended to\nnon-orthogonal basis set. The most important techniques for applications are\nthe shifted equation and the seed switching method, which make the\ncomputational cost be reduced much. We, then, present some applications to\nelectronic structure calculations with MD simulation. The applications are\ngiven to the fracture propagation in nano-scale Si crystals and the proton\ntransfer in water."
    },
    {
        "anchor": "Data-driven research on chemical features of Jingdezhen and Longquan\n  celadon by energy dispersive X-ray fluorescence: The energy dispersive X-ray fluorescence (EDXRF) is used to determine the\nchemical composition of celadon body and glaze in Longquan kiln (at Dayao\nCounty) and Jingdezhen kiln. Forty typical shards in four cultural eras were\nselected to investigate the raw materials and firing technology. Random\nforests, a relatively new statistical technique, has been adopted to identify\nchemical elements that are strongest explanatory variables to classify samples\ninto defferent cultural eras and kilns. The results indicated that the contents\nof Na2O, Fe2O3, TiO2, SiO2 and CaO vary in celadon bodies from Longquan and\nJingdezhen, which implies that local clay was used to manufacture celadon\nbodies in Jingdezhen kiln. By comparing the chemical composition in glaze, we\nfind that the chemical elements and firing technology of Jingdezhen kiln are\nvery similar to those in Longquan kiln, especially for Ming dynasty. This study\nreveals the inheritance between Jingdezhen kiln and Longquan kiln, and explains\nthe differences between those two kilns.",
        "positive": "Colossal room-temperature electrocaloric strength aided by hydrostatic\n  pressure in lead-free multiferroic solid solutions: Solid-state cooling applications based on the electrocaloric (EC) effect are\nparticularly promising from a technological point of view due to their downsize\nscalability and natural implementation in circuitry. However, EC effects\ntypically occur far from room temperature, involve materials that contain toxic\nsubstances and require relatively large electric fields ($\\sim 100$-$1000$ kV\ncm$^{-1}$) that cause fateful leakage current and dielectric loss problems.\nHere, we propose a possible solution to these practical issues that consists in\nconcertedly applying hydrostatic pressure and electric fields on lead-free\nmultiferroic materials. We theoretically demonstrate this strategy by\nperforming first-principles simulations on supertetragonal\nBiFe$_{1-x}$Co$_{x}$O$_{3}$ solid solutions (BFCO). It is shown that\nhydrostatic pressure, besides adjusting the occurrence of EC effects to near\nroom temperature, can reduce enormously the intensity of the driving electric\nfields. For pressurized BFCO, we estimate a colossal room-temperature EC\nstrength, defined like the ratio of the adiabatic EC temperature change by the\napplied electric field, of $\\sim 1$ K cm kV$^{-1}$, a value that is several\norders of magnitude larger than those routinely measured in uncompressed\nferroelectrics."
    },
    {
        "anchor": "Oxide spinels with superior Mg conductivity: Mg batteries with oxide cathodes have the potential to significantly surpass\nexisting Li-ion technologies in terms of sustainability, abundance, and energy\ndensity. However, Mg intercalation at the cathode is often severely hampered by\nthe sluggish kinetics of Mg$^{2+}$ migration within oxides. Here we report a\ncombined theoretical and experimental study addressing routes to identify\ncathode materials with an improved Mg-ion mobility. Using periodic density\nfunctional theory calculations, Mg$^{2+}$ migration in oxide spinels has been\nstudied, revealing key features that influence the activation energy for\nMg$^{2+}$ migration. Furthermore, the electronic and geometrical properties of\nthe oxide spinels as well as their stability have been analyzed for a series of\ndifferent transition metals in the spinels. We find that electronegative\ntransition metals enable a high Mg-ion mobility in the oxide spinel frameworks\nand thus a favorable cathode functionality. Based on the theoretical findings,\nsome promising candidates have been identified, prepared and structurally\ncharacterized. Our combined theoretical and experimental findings open up an\navenue toward the utilization of functional cathode materials with improved\nMg$^{2+}$ transport properties for Mg-metal batteries.",
        "positive": "Stability of charged sulfur vacancies in 2D and bulk MoS$_2$ from\n  plane-wave density functional theory with electrostatic corrections: Two-dimensional (2D) semiconducting transition metal dichalcogenides such as\nMoS$_2$ have attracted extensive research interests for potential applications\nin optoelectronics, spintronics, photovoltaics, and catalysis. To harness the\npotential of these materials for electronic devices requires a better\nunderstanding of how defects control the carrier concentration, character, and\nmobility. Utilizing a correction scheme developed by Freysoldt and Neugebauer\nto ensure the appropriate electrostatic boundary conditions for charged defects\nin 2D materials, we perform density functional theory calculations to compute\nformation energies and charge transition levels associated with sulfur\nvacancies in monolayer and layered bulk MoS$_2$. We investigate the convergence\nof these defect properties with respect to vacuum spacing, in-plane supercell\ndimensions, and different levels of theory. We also analyze the electronic\nstructures of the defects in different charge states to gain insights into the\neffect of defects on bonding and magnetism. We predict that both vacancy\nstructures undergo a Jahn-Teller distortion, which helps stabilize the sulfur\nvacancy in the $-1$ charged state."
    },
    {
        "anchor": "Exchange interactions and Tc in rhenium doped silicon: DFT, DFT+U and\n  Monte Carlo calculations: Interactions between rhenium impurities in silicon are investigated by means\nof the density functional theory (DFT) and the DFT+U scheme. All couplings\nbetween impurities are ferromagnetic except the Re-Re dimers which in the DFT\nmethod are nonmagnetic, due to formation of the chemical bond supported by\nsubstantial relaxation of the geometry. The critical temperature is calculated\nby means of classical Monte Carlo (MC) simulations with the Heisenberg\nhamiltonian. The uniform ferromagnetic phase is obtained with the DFT exchange\ninteractions at room temperature for the impurities concentration of 7%. With\nthe DFT+U exchange interactions, the ferromagnetic clusters form above room\ntemperature in MC samples containing only 3% Re.",
        "positive": "Electronic and Optical Properties of ZnIn$_2$Te$_4$: Band structure and optical properties of defect- Chalcopyrite type\nsemiconductor ZnIn$_2$Te$_4$ have been studied by TB-LMTO first principle\ntechnique. The optical absorption calculation suggest that ZnIn$_2$Te$_4$ is a\ndirect-gap semiconductor having a band gap of 1.40 eV., which confirms the\nexperimentally measured value. The calculated complex dielectric-function\n$\\epsilon(E) = \\epsilon_1(E) + i\\epsilon_2(E)$ reveal distinct structures at\nenergies of the critical points in the Brillouin zone."
    },
    {
        "anchor": "Raman spectra and Magnetization of all-ferromagnetic superlattices grown\n  on (110) oriented SrTiO3: Superlattices consist of two ferromagnets La0.7Sr0.3MnO3(LSMO)and SrRuO3(SRO)\nwere grown in (110)-orientation on SrTiO3(STO) substrates. The x-ray\ndiffraction and Raman spectra of these superlattices show the presence of\nin-plane compressive strain and orthorhombic structure of less than 4 u.c.\nthick LSMO spacer,respectively. Magnetic measurements reveal several features\nincluding reduced magnetization, enhanced coercivity, antiferromagnetic\ncoupling, and switching from antiferromagnetic to ferromagnetic coupling with\nmagnetic field orientations. These magnetic properties are explained by the\nobserved orthorhombic structure of spacer LSMO in Raman scattering which occurs\ndue to the modification in the stereochemistry of Mn at the interfaces of SRO\nand LSMO.",
        "positive": "Suppressed magnetization in\n  La$_{0.7}$Ca$_{0.3}$MnO$_3$/YBa$_2$Cu$_3$O$_{7-\u03b4}$ superlattices: We studied the magnetic properties of La$_{0.7}$Ca$_{0.3}$MnO$_3$ /\nYBa$_2$Cu$_3$O$_{7-\\delta}$ superlattices. Magnetometry showed that with\nincreasing YBa$_2$Cu$_3$O$_{7-\\delta}$ layer thickness the saturation\nmagnetization per La$_{0.7}$Ca$_{0.3}$MnO$_3$ layer decreases. From polarized\nneutron reflectometry we determined that this magnetization reduction is due to\nan inhomogenous magnetization depth profile arising from the suppression of\nmagnetization near the La$_{0.7}$Ca$_{0.3}$MnO$_3$ /\nYBa$_2$Cu$_3$O$_{7-\\delta}$ interface. Electron energy loss spectroscopy\nindicates an increased 3d band occupation of the Mn atoms in the\nLa$_{0.7}$Ca$_{0.3}$MnO$_3$ layers at the interface. Thus, the suppression of\nferromagnetic order at the La$_{0.7}$Ca$_{0.3}$MnO$_3$ /\nYBa$_2$Cu$_3$O$_{7-\\delta}$ interface is most likely due to charge transfer\nbetween the two materials."
    },
    {
        "anchor": "Monte Carlo study of the transverse susceptibility in ordered arrays of\n  magnetic nanoparticles: We present Monte Carlo simulations of the reversible transverse\nsusceptibility (RTS) for a hexagonal array of dipolar interacting magnetic\nnanoparticles with random anisotropy. RTS curves with the bias-field in-plane\nand out-of-plane are compared. With increasing temperature the RTS curves\nevolve from a three-peak structure to a double-peak and eventually a\nsingle-peak at the blocking temperature of the system. This trend is preserved\nfor weak interactions. Dipolar interactions at low temperature are responsible\nfor the suppression of the coercivity peak in the out-of-plane geometry and its\nprogressive merge to the anisotropy peak with decreasing interparticle\nseparation in the in-plane geometry. The anisotropy peaks are located at higher\nfield values in the out-of-plane geometry relative to the in-plane one. When\nthe bias field lies in-plane (out-of-plane) the anisotropy peaks are shown to\nshift to lower (higher) field values with decreasing interparticle separation.\nThe coercivity peak shifts to lower field values in both geometries. Our\nresults are compared with recent experimental findings in self-assembled arrays\nof Fe nanoparticles.",
        "positive": "Hybrid Optical Modes in Hexagonal Crystals: In nanostructure electronic devices, it is well-known that the optical\nlattice waves in the constituent semiconductor crystals have to obey both\nmechanical and electrical boundary conditions at an interface. The theory of\nhybrid optical modes, established for cubic crystals, is here applied to\nhexagonal crystals. In general, the hybrid is a linear combination of a\nlongitudinally-polarized (LO) mode, an interface mode (IF), and an interface TO\nmode. It is noted that the dielectric and elastic anisotropy of these crystals\nadd significant complications to the assessment of the electro-phonon\ninteraction. We point out that, where extreme accuracy is not needed, a cubic\napproximation is available. The crucial role of lattice dispersion is\nemphasised. In the extreme long-wavelength limit, where lattice dispersion is\nunimportant, the polar optical hybrid consists of an LO component plus an IF\ncomponent only. In his case no fields are induced in the barrier, and there are\nno remote-phonon effects."
    },
    {
        "anchor": "Temperature-dependent optical properties of plasmonic titanium nitride\n  thin films: Due to their exceptional plasmonic properties, noble metals such as gold and\nsilver have been the materials of choice for the demonstration of various\nplasmonic and nanophotonic phenomena. However, noble metals' softness, lack of\ntailorability and low melting point along with challenges in thin film\nfabrication and device integration have prevented the realization of real-life\nplasmonic devices.In the recent years, titanium nitride (TiN) has emerged as a\npromising plasmonic material with good metallic and refractory (high\ntemperature stable) properties. The refractory nature of TiN could enable\npractical plasmonic devices operating at elevated temperatures for energy\nconversion and harsh-environment industries such as gas and oil. Here we report\non the temperature dependent dielectric functions of TiN thin films of varying\nthicknesses in the technologically relevant visible and near-infrared\nwavelength range from 330 nm to 2000 nm for temperatures up to 900 0C using\nin-situ high temperature ellipsometry. Our findings show that the complex\ndielectric function of TiN at elevated temperatures deviates from the optical\nparameters at room temperature, indicating degradation in plasmonic properties\nboth in the real and imaginary parts of the dielectric constant. However, quite\nstrikingly, the relative changes of the optical properties of TiN are\nsignificantly smaller compared to its noble metal counterparts. Using\nsimulations, we demonstrate that incorporating the temperature-induced\ndeviations into the numerical models leads to significant differences in the\noptical responses of high temperature nanophotonic systems. These studies hold\nthe key for accurate modeling of high temperature TiN based optical elements\nand nanophotonic systems for energy conversion, harsh-environment sensors and\nheat-assisted applications.",
        "positive": "Effect of seed layer thickness on Ta crystalline phase and spin Hall\n  angle: Heavy metal-ferromagnet bilayer structures have attracted great research\ninterest for charge-to-spin interconversion. In this work, we have investigated\nthe effect of the permalloy seed layer on the Ta polycrystalline phase and its\nspin Hall angle. Interestingly, for the same deposition rates the crystalline\nphase of Ta deposited on Py seed layer strongly depends on the thickness of the\nseed layer. We have observed a phase transition from $\\alpha$-Ta to\n($\\alpha$+$\\beta$)-Ta while increasing the Py seed layer thickness. The\nobserved phase transition is attributed to the strain at interface between Py\nand Ta layers. Ferromagnetic resonance-based spin pumping studies reveal that\nthe spin-mixing conductance in the to ($\\alpha$+$\\beta$)-Ta is relatively\nhigher as compared to the to $\\alpha$-Ta. Spin Hall angles of to $\\alpha$-Ta\nand to ($\\alpha$+$\\beta$)-Ta are extracted from inverse spin Hall effect (ISHE)\nmeasurements. Spin Hall angle of the to ($\\alpha$+$\\beta$)-Ta is estimated to\nbe $\\theta$_SH=-0.15 which is relatively higher than that of to $\\alpha$-Ta.\nOur systematic results connecting the phase of the Ta with seed layer and its\neffect on the efficiency of spin to charge conversion might resolve ambiguities\nacross various literature and open up new functionalities based on the growth\nprocess for the emerging spintronic devices."
    },
    {
        "anchor": "Composition dependence of magnetocaloric effect in Sm1-xSrxMnO3 (x =\n  0.3-0.5): We investigated magnetic and magnetocaloric properties in Sm1-xSrxMnO3 (x =\n0.30-0.5). We report a magnetic field driven first-order metamagnetic\ntransition in the paramagnetic state in x = 0.4 and 0.5 and a second-order\ntransition in x = 0.3. The highest magnetic entropy (-Sm = 6.2 J/kgK for H = 5\nT at T = 125 K) that occurs in x = 0.4 is associated with the metamagnetic\ntransition resulting from the field-induced growth and coalescence of\nferromagnetic nano clusters preexisting in the paramagnetic state. Our results\nsuggest that manganites with intrinsic nanoscale phase separation can be\nexploited for magnetic refrigeration.",
        "positive": "Spin-injection through an Fe/InAs Interface: The spin-dependence of the interface resistance between ferromagnetic Fe and\nInAs is calculated from first-principles for specular and disordered (001)\ninterfaces. Because of the symmetry mismatch in the minority-spin channel, the\nspecular interface acts as an efficient spin filter with a transmitted current\npolarisation between 98 an 89%.\n  The resistance of a specular interface in the diffusive regime is comparable\nto the resistance of a few microns of bulk InAs.\n  Symmetry-breaking arising from interface disorder reduces the spin asymmetry\nsubstantially and we conclude that efficient spin injection from Fe into InAs\ncan only be realized using high quality epitaxial interfaces."
    },
    {
        "anchor": "Nanoscale Self-Healing Mechanisms in Shape Memory Ceramics: Shape memory (SM) ceramics, such as yttria-stabilized tetragonal zirconia\n(YSTZ), are a unique family of SM materials that offer unique properties\nincluding ultra-high operating temperature, and high resistance to chemical\ncorrosion and oxidation. However, formation of defects is usually observed in\nSM ceramics during manufacturing and/or by mechanical deformation. To fully\ntake advantage of the SM properties of these ceramics, it is necessary to fully\nunderstand the nano-structural evolution of defects under external stimuli. In\nthis study, defect closure behaviors in YSTZ nanopillars are investigated by\natomistic simulations. Two characteristic orientations of [011-] and [001] are\nselected to represent the dominant deformation mechanisms of phase\ntransformation and dislocation migration, respectively. With the presence of\ncrack and void, the strength and yield strain of nanopillars are noted to\ndecrease significantly, especially for [011-]-oriented YSTZ nanopillars. Volume\nexpansion associated with the tetragonal to monoclinic phase transformation is\nobserved to promote healing of crack and void. Atom stress analyses reveal\nstress concentrations along the newly formed monoclinic phase bands. A critical\ncrack width is identified, less than which the crack can be fully closed in\ncompression. Size effect study reveals that an increase in nanopillar size has\na positive effect on crack self-healing behavior. For [001]-oriented YSTZ\nnanopillars, dislocation migration leads to formations of an amorphous phase,\nwhich also assist the crack and void closure process. The revealed crack/void\nhealing mechanisms may provide a path for mitigating internal defects that\ninfluences the mechanical properties and deformation mechanisms of SM ceramics.",
        "positive": "Dependence of nonthermal metallization kinetics on bond ionicity of\n  compounds: It is known that covalently bonded materials undergo nonthermal structure\ntransformations upon ultrafast excitation of an electronic system, whereas\nmetals exhibit phonon hardening. Here we study how ionic bonds react to\nelectronic excitation. Density-functional molecular dynamics predicts that\nionic crystals may melt nonthermally, however, into an electronically\ninsulating state, in contrast to covalent materials. We demonstrate that the\nband gap behavior during nonthermal transitions depends on a bonding type: it\nis harder to collapse the band gap in more ionic compounds, which is\nillustrated by transformations in Y2O3 vs. NaCl, LiF and KBr."
    },
    {
        "anchor": "Beyond Walker Breakdown through the Resonant Dissipation: Dramatic\n  Enhancement of Magnetic Domain Wall Velocity via Resonant Excitation of\n  Standing Wave Modes of Domain Wall Structure: The dynamic behaviors of magnetic domain walls have significant implications\nfor developing advanced spintronic devices. In this study, we investigate the\nintriguing resonance phenomenon within the magnetic domain wall structure and\nits profound influence on dynamic motion, focusing on the dissipation\nmechanism. By applying a static external magnetic field, we observe a\nremarkable amplification of domain wall velocity, surpassing the limitations of\nthe conventional one-dimensional model. To quantify this enhancement, we\nintroduce a novel parameter, the distortion variation rate, which captures the\nrapid and pronounced changes occurring within the domain wall structure.\nThrough comprehensive micromagnetic simulations, we establish a robust\nrelationship between speed and distortion variation rate, thereby validating\nour theoretical framework. Our findings provide crucial insights into the\nunderlying mechanisms governing domain wall dynamics while paving the way for\ndeveloping and optimizing next-generation spintronic devices boasting\nunparalleled speed and efficiency.",
        "positive": "Fe3O4(001) films on Fe(001) - termination and reconstruction of iron\n  rich surfaces: High-quality and impurity-free magnetite surfaces with (sqrt2xsqrt2)R45o\nreconstruction have been obtained for the Fe3O4(001) epitaxial films deposited\non Fe(001). Based on atomically resolved STM images for both negative and\npositive sample polarity and Density Functional Theory calculations, a model of\nthe magnetite (001) surface terminated with Fe ions forming dimers on the\nreconstructed (sqrt2xsqrt2)R45o octahedral iron layer is proposed."
    },
    {
        "anchor": "Towards wafer scale inductive characterization of spin transfer torque\n  critical current density of magnetic tunnel junction stacks: We explore the prospects of wafer scale inductive probing of the critical\ncurrent density $j^{c0}$ for spin transfer torque switching of a\nCoFeB/MgO/CoFeB magnetic tunnel junction with varying MgO thickness. From\ninductive measurements magnetostatic parameters and the effective damping are\nderived and $j^{c0}$ is calculated based on spin transfer torque equations. The\ninductive values compare well to the values derived from current induced\nswitching measurements on individual nanopillars. Using a wafer scale inductive\nprobe head could in the future enable wafer probe station based metrology of\n$j^{c0}$.",
        "positive": "AI-accelerated Discovery of Altermagnetic Materials: Altermagnetism, a new magnetic phase, has been theoretically proposed and\nexperimentally verified to be distinct from ferromagnetism and\nantiferromagnetism. Although altermagnets have been found to possess many\nexotic physical properties, the very limited availability of known\naltermagnetic materials (e.g., 14 confirmed materials) hinders the study of\nsuch properties. Hence, discovering more types of altermagnetic materials is\ncrucial for a comprehensive understanding of altermagnetism and thus\nfacilitating new applications in the next-generation information technologies,\ne.g., storage devices and high-sensitivity sensors. Here, we report 25 new\naltermagnetic materials that cover metals, semiconductors, and insulators,\ndiscovered by an AI search engine unifying symmetry analysis, graph neural\nnetwork pre-training, optimal transport theory, and first-principles electronic\nstructure calculation. The wide range of electronic structural characteristics\nreveals that various novel physical properties manifest in these newly\ndiscovered altermagnetic materials, e.g., anomalous Hall effect, anomalous Kerr\neffect, and topological property. Noteworthy, we discovered 8 i-wave\naltermagnetic materials for the first time. Overall, the AI search engine\nperforms much better than human experts and suggests a set of new altermagnetic\nmaterials with unique properties, outlining its potential for accelerated\ndiscovery of the materials with targeting properties."
    },
    {
        "anchor": "Coexistence of topological Weyl and nodal-ring states in ferromagnetic\n  and ferrimagnetic double perovskites: Magnetic topological quantum materials have attracted great attention due to\ntheir exotic topological quantum physics induced by the interplay among\ncrystalology, magnetism, and topology, which is of profound importance to\nfundamental research and technology applications. However, limited materials\nare experimentally available, most of whom are realized by magnetic impurity\ndoping or heterostructural constructions. In this work, based on the\nfirst-principles calculations, we predict that double perovskite Ba2CdReO6 is\nan intrinsic ferromagnetic topological semi-half-metal, while the ferrimagnetic\ndouble perovskite with space group symmetry Fm-3m, such as Ba2FeMoO6, belongs\nto a topological half-metal. One pair of Weyl points and fully spin-polarized\nnodal-ring states are found in the vicinity of the Fermi level in Ba2CdReO6.\nIts two-dimensional nearly flat drumhead surface states are fully\nspin-polarized. In Ba2FeMoO6, however, there exist four pairs of Weyl points\nand two fully spin-polarized nodal-rings near the Fermi level. These\ntopological properties are stable in the presence of spin-orbit coupling. This\nmakes these materials be an appropriate platform for studying the emerging\nintriguing properties, especially for the applications in spintronics,\ninformation technology, and topological superconductivity.",
        "positive": "SPD deformation of pearlitic, bainitic and martensitic steels: The deformation behavior of nearly fully pearlitic, bainitic and martensitic\nsteels during severe plastic deformation is summarized in this paper. Despite\ntheir significantly different yield stresses and their microstructures, their\nhardening behavior during SPD is similar. Due to the enormous hardening\ncapacity the SPD deformation is limited by the strength of the tool materials.\nThe microstructure at the obtainable limit of strain are quite similar, which\nis a nanocrystalline structure in the order of 10 nm, dependent on the\nobtainable strain. The nanograins are partially supersaturated with carbon and\nthe grain boundaries are stabilized by carbon. Another characteristic feature\nis the anisotropy in grain shape which results in an anisotropy of strength,\nductility and fracture toughness. The results are important for the development\nof ultra-strong materials and essential for this type of steels which are\nfrequently used for application where the behavior under rolling contact and\nsliding contact is important."
    },
    {
        "anchor": "Machine Learning-Driven Structure Prediction for Iron Hydrides: We created a computational workflow to analyze the potential energy surface\n(PES) of materials using machine-learned interatomic potentials in conjunction\nwith the minima hopping algorithm. We demonstrate this method by producing a\nversatile machine-learned interatomic potential for iron hydride via a neural\nnetwork using an iterative training process to explore its energy landscape\nunder different pressures. To evaluate the accuracy and comprehend the\nintricacies of the PES, we conducted comprehensive crystal structure\npredictions using our neural network-based potential paired with the minima\nhopping approach. The predictions spanned pressures ranging from ambient to 100\nGPa. Our results reproduce the experimentally verified global minimum\nstructures such as \\textit{dhcp}, \\textit{hcp}, and \\textit{fcc}, corroborating\nprevious findings. Furthermore, our in-depth exploration of the iron hydride\nPES at different pressures has revealed complex alterations and stacking faults\nin these phases, leading to the identification of several new low-enthalpy\nstructures. This investigation has not only confirmed the presence of regions\nof established FeH configurations but has also highlighted the efficacy of\nusing data-driven, extensive structure prediction methods to uncover the\nmultifaceted PES of materials.",
        "positive": "Improvement in thermoelectric properties by tailoring at In and Te site\n  in In2Te5: We study role of site substitutions at In and Te site in In2Te5 on the\nthermoelectric behavior. Single crystals with compositions In2(Te1-xSex)5 (x =\n0, 0.05, 0.10) and Fe0.05In1.95(Te0.90Se0.10)5 were prepared using modified\nBridgman-Stockbarger technique. Electrical and thermal transport properties of\nthese single crystals were measured in the temperature range 6 - 395 K. A\nsubstantial decrease in thermal conductivity is observed in Fe substituted\nsamples attributed to the enhanced phonon point-defect scattering. Marked\nenhancement in Seebeck coefficient S along with a concomitant suppression of\nelectrical resistivity \\r{ho} is observed in Se substituted single crystals. An\noverall enhancement of thermoelectric figure of merit (zT) by a factor of 310\nis observed in single crystals of Fe0.05In1.95(Te0.90Se0.10)5 compared to the\nparent In2Te5 single crystals."
    },
    {
        "anchor": "Density functional method for nonequilibrium electron transport: We describe an ab initio method for calculating the electronic structure,\nelectronic transport, and forces acting on the atoms, for atomic scale systems\nconnected to semi-infinite electrodes and with an applied voltage bias. Our\nmethod is based on the density functional theory (DFT) as implemented in the\nwell tested Siesta approach (which uses non-local norm-conserving\npseudopotentials to describe the effect of the core electrons, and linear\ncombination of finite-range numerical atomic orbitals to describe the valence\nstates). We fully deal with the atomistic structure of the whole system,\ntreating both the contact and the electrodes on the same footing. The effect of\nthe finite bias (including selfconsistency and the solution of the\nelectrostatic problem) is taken into account using nonequilibrium Green's\nfunctions. We relate the nonequilibrium Green's function expressions to the\nmore transparent scheme involving the scattering states. As an illustration,\nthe method is applied to three systems where we are able to compare our results\nto earlier ab initio DFT calculations or experiments, and we point out\ndifferences between this method and existing schemes. The systems considered\nare: (1) single atom carbon wires connected to aluminum electrodes with\nextended or finite cross section, (2) single atom gold wires, and finally (3)\nlarge carbon nanotube systems with point defects.",
        "positive": "Secondary Phase Limited Metal-Insulator Phase Transition in Chromium\n  Nitride Thin Films: Chromium nitride (CrN) is a well-known hard coating material that has found\napplications in abrasion and wear-resistant cutting tools, bearings, and\ntribology applications due to its high hardness, high-temperature stability,\nand corrosion-resistant properties. In recent years, CrN has also attracted\nsignificant interest due to its high thermoelectric power factor, and for its\nunique and intriguing metal-insulator phase transition. While CrN bulk\nsingle-crystals exhibit the characteristic metal-insulator transition\naccompanied with structural (orthorhombic-to-rocksalt) and magnetic\n(antiferromagnetic-to-paramagnetic) transition at ~260-280K, observation of\nsuch phase transition in thin-film CrN has been scarce and highly debated. In\nthis work, the formation of the secondary metallic Cr2N phase during the growth\nis demonstrated to inhibit the observation of metal-insulator phase transition\nin CrN thin films. When the Cr-flux during deposition is reduced below a\ncritical limit, epitaxial and stoichiometric CrN thin film is obtained that\nreproducibly exhibits the phase transition. Annealing of the mixed-phase film\ninside reducing NH3 environment converts the Cr2N into CrN, and a discontinuity\nin the electrical resistivity at ~ 277 K appears which supports the underlying\nhypothesis. A clear demonstration of the origin behind the controversy of the\nmetal-insulator transition in CrN thin films marks significant progress and\nwould enable its nanoscale device realization."
    },
    {
        "anchor": "Tunable Magnetic Transition to a Singlet Ground State in a 2D Van der\n  Waals Layered Trimerized Kagom\u00e9 Magnet: Incorporating magnetism into two dimensional (2D) van der Waals (VdW)\nheterostrutures is crucial for the development of functional electronic and\nmagnetic devices. Here we show that Nb3X8 (X = Cl, Br) is a family of 2D\nlayered trimerized kagom\\'e magnets that are paramagnetic at high temperatures\nand undergo a first order phase transition on cooling to a singlet magnetic\nstate. X-ray diffraction shows that a rearrangement of the VdW stacking\naccompanies the magnetic transition, with high and low temperature phases\nconsistent with STEM images of the end members {\\alpha}-Nb3Cl8 and\n\\b{eta}-Nb3Br8. The temperature of this transition is systematically varied\nacross the solid solution Nb3Cl8-xBrx (x = 0-8), with x = 6 having transitions\nnear room temperature. The solid solution also varies the optical properties,\nwhich are further modulated by the phase transition. As such, they provide a\nplatform on which to understand and exploit the interplay between\ndimensionality, magnetism, and optoelectronic behavior in VdW materials.",
        "positive": "Comment on \"Modeling oxygen self-diffusion in UO2 under pressure by\n  M.W.D Cooper et al., Solid State Ionics 282 (2015) 26-30\": The oxygen self-diffusion coefficient in UO${_2}$ has been recently studied\n[Cooper et al. Solid State Ionics 282 (2015) 26-30] over a range of pressures\n(0-10GPa) and temperatures (300-1900K) by combining molecular dynamics\ncalculations with a thermodynamical model, the cB{\\Omega} model. A significant\nreduction in oxygen self-diffusion as a function of increasing hydrostatic\npressure, and the associated increase in activation energy was identified.\nHere, we extend this study and find that the compressibility of the\ncorresponding activation volume exceeds significantly the compressibility of\nthe bulk material by almost one order of magnitude. This results is important\nsince in the literature it is usually assumed that these two compressibilities\nare equal. The same holds when comparing the thermal expansion coefficient of\nthis volume with that of the bulk solid."
    },
    {
        "anchor": "Vibrational Behavior of Metal Nanowires under Tensile Stress: We have investigated the vibrational density of states (VDOS) of a thin Cu\nnanowire with $<100>$ axial orientation and considered the effect of axial\nstrain. The VDOS are calculated using a real space Green's function approach\nwith the force constant matrices extracted from interaction potential based on\nthe embedded atom method. Results for the vibrational density of states of a\nstrain-free nanowire show quite distinctive characteristics compared to that of\na bulk atom, the most striking feature of which is the existence of high\nfrequency modes above the top of the bulk spectrum. We further predict that the\nlow frequency characteristics of the VDOS reveal the quasi-1 dimensional (Q1D)\nbehavior only when the wire is extremely thin. Through decomposition of VDOS\ninto local atoms we also exhibit that while the anomalous increase in low\nfrequency density of states is mainly due to the corner atoms, the enhancement\nin high frequency modes is primarily moderated by core atoms. We, additionally,\nfind that while the high frequency band above the top of the bulk phonon shifts\nto higher frequencies, the characteristics at low frequencies remains almost\nthe same upon stretching the nanowire along the axial direction.",
        "positive": "Analysis of the attainable efficiency of a direct-bandgap betavoltaic\n  element: Conversion of energy of beta-particles into electric energy in a p-n junction\nbased on direct-bandgap semiconductors, such as GaAs, considering realistic\nsemiconductor system parameters is analyzed. An expression for the collection\ncoefficient, $Q$, of the electron-hole pairs generated by beta-electrons is\nderived taking into account the existence of the dead layer. We show that the\ncollection coefficient of beta-electrons emitted by a \\Tr-source to a GaAs p-n\njunction is close to 1 in a broad range of electron lifetimes in the junction,\nranging from $10^{-9}$ to $10^{-7}$ s. For the combination \\Pm/GaAs, $Q$ is\nrelatively large ($\\ge 0.4$) only for quite long lifetimes (about $10^{-7}$ s)\nand large thicknesses (about $100\\,\\mu$m) of GaAs p-n junctions. For realistic\nlifetimes of minority carriers and their diffusion coefficients, the\nopen-circuit voltage realized due to the irradiation of a GaAs p-n junction by\nbeta-particles is obtained. The attainable beta-conversion efficiency $\\eta$ in\nthe case of a \\Tr/GaAs combination is found to exceed that of the \\Pm/GaAs\ncombination."
    },
    {
        "anchor": "Theory and Experiments of Pressure-Tunable Broadband Light Emission from\n  Self-Trapped Excitons in Metal Halide Crystals: Hydrostatic pressure has been commonly applied to tune broadband light\nemissions from self-trapped excitons (STE) in perovskites for producing white\nlight and study of basic electron-phonon interactions. However, a general\ntheory is still lacking to understand pressure-driven evolution of STE\nemissions. In this work we first identify a theoretical model that predicts the\neffect of hydrostatic pressure on STE emission spectrum, we then report the\nobservation of extremely broadband photoluminescence emission and its wide\npressure spectral tuning in 2D indirect bandgap CsPb2Br5 crystals. An excellent\nagreement is found between the theory and experiment on the peculiar\nexperimental observation of STE emission with a nearly constant spectral\nbandwidth but linearly increasing energy with pressure below 2 GPa. Further\nanalysis by the theory and experiment under higher pressure reveals that two\ntypes of STE are involved and respond differently to external pressure. We\nsubsequently survey published STE emissions and discovered that most of them\nshow a spectral blue-shift under pressure, as predicted by the theory. The\nidentification of an appropriate theoretical model and its application to STE\nemission through the coordinate configuration diagram paves the way for\nengineering the STE emission and basic understanding of electron-phonon\ninteraction.",
        "positive": "Observation of low-frequency Raman peak in layered WTe$_2$: WTe$_2$ recently attracted considerable attention as a layered material\nexhibiting ferroelectricity, giant magnetoresistance, and pressure-induced\nsuperconductivity. In this study, we performed Raman spectroscopy on bulk\nWTe$_2$, including the unreported low frequency region. A novel Raman peak (P0)\nwas found at approximately 9 cm$^{-1}$ in addition to the seven already known\npeaks. Furthermore, the angular and polarization dependence of the spectra\nrevealed that the novel peak had $A_1$ symmetry. The existence of this novel\npeak is consistent with first principles calculations by another group. Our\nwork paves the way for studying the low frequency vibration modes of atomic\nlayer ferrolectric films."
    },
    {
        "anchor": "Covalency, correlations, and inter-layer interactions governing the\n  magnetic and electronic structure of Mn$_3$Si$_2$Te$_6$: Mn$_3$Si$_2$Te$_6$ is a rare example of a layered ferrimagnet. It has\nrecently been shown to host a colossal angular magnetoresistance as the spin\norientation is rotated from the in- to out-of-plane direction, proposed to be\nunderpinned by a topological nodal-line degeneracy in its electronic structure.\nNonetheless, the origins of its ferrimagnetic structure remain controversial,\nwhile its experimental electronic structure, and the role of correlations in\nshaping this, are little explored to date. Here, we combine x-ray and\nphotoemission-based spectroscopies with first-principles calculations, to probe\nthe elemental-selective electronic structure and magnetic order in\nMn$_3$Si$_2$Te$_6$. Through these, we identify a marked Mn-Te hybridisation,\nwhich weakens the electronic correlations and enhances the magnetic anisotropy.\nWe demonstrate how this strengthens the magnetic frustration in\nMn$_3$Si$_2$Te$_6$, which is key to stabilising its ferrimagnetic order, and\nfind a crucial role of both exchange interactions extending beyond\nnearest-neighbours and anti-symmetric exchange in dictating its ordering\ntemperature. Together, our results demonstrate a powerful methodology of using\nexperimental electronic structure probes to constrain the parameter space for\nfirst-principles calculations of magnetic materials, and through this approach,\nreveal a pivotal role played by covalency in stabilising the ferrimagnetic\norder in Mn$_3$Si$_2$Te$_6$.",
        "positive": "Six-fold Excitations in Electrides: Due to the lack of full rotational symmetry in condensed matter physics,\nsolids exhibit new excitations beyond Dirac and Weyl fermions, of which the\nsix-fold excitations have attracted considerable interest owing to the presence\nof the maximum degeneracy in bosonic systems. Here, we propose that a single\nlinear dispersive six-fold excitation can be found in the electride\nLi$_{12}$Mg$_3$Si$_4$ and its derivatives. The six-fold excitation is formed by\nthe floating bands of elementary band representation -- $A@12a$ -- originating\nfrom the excess electrons centered at the vacancies (${\\it i.e.}$, the $12a$\nWyckoff sites). There exists a unique topological bulk-surface-edge\ncorrespondence for the spinless six-fold excitation, resulting in trivial\nsurface 'Fermi arcs' but nontrivial hinge arcs. All energetically-gapped\n$k_z$-slices belong to a two-dimensional (2D) higher-order topological\ninsulating phase, which is protected by a combined symmetry ${\\mathcal\nT}{\\widetilde S_{4z}}$ and characterized by a quantized fractional corner\ncharge $Q_{corner}=\\frac{3|e|}{4}$. Consequently, the hinge arcs are obtained\nin the hinge spectra of the $\\widetilde S_{4z}$-symmetric rod structure. The\nstate with a single six-fold excitation, stabilized by both nonsymmorphic\ncrystalline symmetries and time-reversal symmetry, is located at the phase\nboundary and can be driven into various topologically distinct phases by\nexplicit breaking of symmetries, making these electrides promising platforms\nfor the systematic studies of different topological phases."
    },
    {
        "anchor": "Experimental signatures of the mixed axial-gravitational anomaly in the\n  Weyl semimetal NbP: Weyl semimetals are materials where electrons behave effectively as a kind of\nmassless relativistic particles known asWeyl fermions. These particles occur in\ntwo flavours, or chiralities, and are subject to quantum anomalies, the\nbreaking of a conservation law by quantum fluctuations. For instance, the\nnumber of Weyl fermions of each chirality is not independently conserved in\nparallel electric and magnetic field, a phenomenon known as the chiral anomaly.\nIn addition, an underlying curved spacetime provides a distinct contribution to\na chiral imbalance, an effect known as the mixed axial-gravitational anomaly,\nwhich remains experimentally elusive. However, the presence of a mixed\ngauge-gravitational anomaly has recently been tied to thermoelectrical\ntransport in a magnetic field, even in flat spacetime, opening the door to\nexperimentally probe such type of anomalies in Weyl semimetals. Using a\ntemperature gradient, we experimentally observe a positive longitudinal\nmagnetothermoelectric conductance (PMTC) in the Weyl semimetal NbP for\ncollinear temperature gradients and magnetic fields (DT || B) that vanishes in\nthe ultra quantum limit. This observation is consistent with the presence of a\nmixed axial-gravitational anomaly. Our work provides clear experimental\nevidence for the existence of a mixed axial-gravitational anomaly of Weyl\nfermions, an outstanding theoretical concept that has so far eluded\nexperimental detection.",
        "positive": "Confined states in photonic-magnonic crystals with complex unit cell: We have investigated multifunctional periodic structures in which\nelectromagnetic waves and spin waves can be confined in the same areas. Such\nsimultaneous localization of both sorts of excitations can potentially enhance\nthe interaction between electromagnetic waves and spin waves. The system we\nconsidered has a form of one dimensional photonic-magnonic crystal with two\ntypes of magnetic layers (thicker and thinner ones) separated by sections of\nthe dielectric photonic crystals. We focused on the electromagnetic defect\nmodes localized in the magnetic layers (areas where spin waves can be exited)\nand decaying in the sections of conventional (nonmagnetic) photonic crystals.\nWe showed how the change of relative thickness of two types of the magnetic\nlayers can influence on the spectrum of spin waves and electromagnetic defect\nmodes, both localized in magnetic parts of the system."
    },
    {
        "anchor": "Construction and analysis of surface phase diagrams to describe\n  segregation and dissolution behavior of Al and Ca in Mg alloys: Segregation and dissolution behavior of Mg alloyed with Ca and Al are studied\nby performing density functional theory calculations considering an extensive\nset of surface structures and compositions. Combining ab initio surface science\napproaches with cluster expansion for ordered surface structures we construct\nsurface phase diagrams for these alloys. We utilize these diagrams to study\nsegregation phenomena and chemical trends for surfaces in contact with a dry\nenvironment or with an aqueous electrolyte. We show that the presence of water\ndramatically impacts the stability and chemical composition of the considered\nmetallic surfaces. We furthermore find that the two alloying elements behave\nqualitatively different: whereas Ca strongly segregates to the surface and\nbecomes dissolved upon exposure of the surface to water, Al shows an\nanti-segregation behavior, i.e., it remains in Mg bulk. These findings provide\nan explanation for the experimentally observed increase/decrease in corrosion\nrates when alloying Mg with Al/Ca.",
        "positive": "Matching the photocurrent of perovskite/organic tandem solar modules by\n  varying the cell width: Photocurrent matching in conventional monolithic tandem solar cells is\nachieved by choosing semiconductors with complementary absorption spectra and\nby carefully adjusting the optical properties of the complete top and bottom\nstacks. However, for thin film photovoltaic technologies at the module level,\nanother design variable significantly alleviates the task of photocurrent\nmatching, namely the cell width, whose modification can be readily realized by\nthe adjustment of the module layout. Herein we demonstrate this concept at the\nexperimental level for the first time for a 2T-mechanically stacked perovskite\n(FAPbBr3)/organic (PM6:Y6:PCBM) tandem mini-module, an unprecedented approach\nfor these emergent photovoltaic technologies fabricated in an independent\nmanner. An excellent Isc matching is achieved by tuning the cell widths of the\nperovskite and organic modules to 7.22 mm (PCEPVKT-mod= 6.69%) and 3.19 mm\n(PCEOPV-mod= 12.46%), respectively, leading to a champion efficiency of 14.94%\nfor the tandem module interconnected in series with an aperture area of 20.25\ncm2. Rather than demonstrating high efficiencies at the level of small lab\ncells, our successful experimental proof-of-concept at the module level proves\nto be particularly useful to couple devices with non-complementary\nsemiconductors, either in series or in parallel electrical connection, hence\novercoming the limitations imposed by the monolithic structure."
    },
    {
        "anchor": "Constructing and Compressing Global Moment Descriptors from Local Atomic\n  Environments: Local atomic environment descriptors (LAEDs) are used in the materials\nscience and chemistry communities, for example, for the development of machine\nlearning interatomic potentials. Despite the fact that LAEDs have been\nextensively studied and benchmarked for various applications, global structure\ndescriptors (GSDs), i.e., descriptors for entire molecules or crystal\nstructures, have been mostly developed independently based on other approaches.\nHere, we propose a systematically improvable methodology for constructing a\nspace of representations of GSDs from LAEDs by incorporating statistical\ninformation and information about chemical elements. We apply the method to\nconstruct GSDs of varying complexity for lithium thiophosphate structures that\nare of interest as solid electrolytes and use an information-theoretic approach\nto obtain an optimally compressed GSD. Finally, we report the performance of\nthe compressed GSD for energy prediction tasks.",
        "positive": "Mechanical Properties of Protomene: A Molecular Dynamics Investigation: Recently, a new class of carbon allotrope called protomene was proposed. This\nnew structure is composed of sp2 and sp3 carbon-bonds. Topologically, protomene\ncan be considered as an sp3 carbon structure (~80% of this bond type) doped by\nsp2 carbons. First-principles simulations have shown that protomene presents an\nelectronic bandgap of ~3.4 eV. However, up to now, its mechanical properties\nhave not been investigated. In this work, we have investigated protomene\nmechanical behavior under tensile strain through fully atomistic reactive\nmolecular dynamics simulations using the ReaxFF force field, as available in\nthe LAMMPS code. At room temperature, our results show that the protomene is\nvery stable and the obtained ultimate strength and ultimate stress indicates an\nanisotropic behavior. The highest ultimate strength was obtained for the\nx-direction, with a value of ~110 GPa. As for the ultimate strain, the highest\none was for the z-direction (~25% of strain) before protomene mechanical\nfracture."
    },
    {
        "anchor": "Accelerating microstructure modelling via machine learning: a new method\n  combining Autoencoder and ConvLSTM: Phase-field modeling is an elegant and versatile computation tool to predict\nmicrostructure evolution in materials in the mesoscale regime. However, these\nsimulations require rigorous numerical solutions of differential equations,\nwhich are accurate but computationally expensive. To overcome this difficulty,\nwe combine two popular machine learning techniques, autoencoder and\nconvolutional long short-term memory (ConvLSTM), to accelerate the study of\nmicrostructural evolution without compromising the resolution of the\nmicrostructural representation. After training with phase-field generated\nmicrostructures of ten known compositions, the model can accurately predict the\nmicrostructure for the future nth frames based on previous m frames for an\nunknown composition. Replacing n phase-field steps with machine-learned\nmicrostructures can significantly accelerate the in silico study of\nmicrostructure evolution.",
        "positive": "Electric field control of spin lifetimes in Nb-SrTiO$_3$ by spin-orbit\n  fields: We show electric field control of the spin accumulation at the interface of\nthe oxide semiconductor Nb-SrTiO$_{3}$ with Co/AlO$_{x}$ spin injection\ncontacts at room temperature. The in-plane spin lifetime $\\tau_\\parallel$ as\nwell as the ratio of the out-of-plane to in-plane spin lifetime\n$\\tau_\\perp/\\tau_\\parallel$ is manipulated by the built-in electric field at\nthe semiconductor surface, without any additional gate contact. The origin of\nthis manipulation is attributed to Rashba Spin-Orbit Fields (SOFs) at the\nNb-SrTiO$_3$ surface and shown to be consistent with theoretical model\ncalculations based on SOF spin flip scattering. Additionally, the junction can\nbe set in a high or low resistance state, leading to a non-volatile control of\n$\\tau_\\perp/\\tau_\\parallel$, consistent with the manipulation of the Rashba SOF\nstrength. Such room temperature electric field control over the spin state is\nessential for developing energy-efficient spintronic devices and shows promise\nfor complex oxide based (spin)electronics"
    },
    {
        "anchor": "An Idealised Approach of Geometry and Topology to the Diffusion of\n  Cations in Honeycomb Layered Oxide Frameworks: Honeycomb layered oxides are a novel class of nanostructured materials\ncomprising alkali or alkaline earth metals intercalated into transition metal\nslabs. The intricate honeycomb architecture and layered framework endows this\nfamily of oxides with a tessellation of features such as exquisite\nelectrochemistry, unique topology and fascinating electromagnetic phenomena.\nDespite having innumerable functionalities, these materials remain highly\nunderutilized as their underlying atomistic mechanisms are vastly unexplored.\nTherefore, in a bid to provide a more in-depth perspective, we propose an\nidealised diffusion model of the charged alkali cations (such as lithium,\nsodium or potassium) in the two-dimensional (2D) honeycomb layers within the\nthree-dimensional (3D) crystal of honeycomb layered oxide frameworks. This\nmodel not only explains the correlation between the excitation of cationic\nvacancies (by applied electromagnetic fields) and the Gaussian curvature\ndeformation of the 2D surface, but also takes into consideration, the quantum\nproperties of the cations and their inter-layer mixing through quantum\ntunnelling. Through this work, we offer a novel theoretical framework for the\nstudy of 3D layered materials with 2D cationic diffusion currents, as well as\nproviding pedagogical insights into the role of topological phase transitions\nin these materials in relation to Brownian motion and quantum geometry.",
        "positive": "Zero-field dynamics stabilized by in-plane shape anisotropy in MgO-based\n  spin-torque oscillators: Here we demonstrate numerically that shape anisotropy in MgO-based\nspin-torque nano-oscillators consisting of an out-of-plane magnetized free\nlayer and an in-plane polarizer is necessary to stabilize out-of-plane\nmagnetization precession without the need of external magnetic fields. As the\nin-plane anisotropy is increased, a gradual tilting of the magnetization\ntowards the in-plane easy direction is introduced, favouring zero-field\ndynamics over static in-plane states. Above a critical value, zero-field\ndynamics are no longer observed. The optimum ratio of in-plane shape to\nout-of-plane uniaxial anisotropy, for which large angle out-of-plane zero-field\ndynamics occur within the widest current range, is reported."
    },
    {
        "anchor": "The common attribute shared by defects, surfaces, and nanostructures:\n  the BOLS-NEP notion: Atomic undercoordination fascinates defects, surfaces, and nanostructures in\nelectronic binding energy, lattice oscillation frequency, elasticity and\nplasticity (IHPR), thermal stability, photon emisibility, reactivity,\ndielectrics, super-hydrophobicity, spin-resolved topological edge and monolayer\nhigh-TC superconductivity, etc., through local bond contraction, quantum\nentrapment and polarization.",
        "positive": "Origin of the superconductivity of WTe2 under pressure: Tungsten ditelluride (WTe2) has attracted significant attention due to its\ninteresting electronic properties, such as the unsaturated magnetoresistance\nand superconductivity. Recently, it has been proposed to be a new type of Weyl\nsemimetal, which is distinguished from other transition metal dichalcogenides\n(TMDs) from a topological prospective. Here, we study the structure of WTe2\nunder pressure with a crystal structure prediction and ab initio calculations\ncombined with high pressure synchrotron X-ray diffraction and Raman\nspectroscopy measurements. We find that the ambient orthorhombic structure (Td)\ntransforms into a monoclinic structure (1T') at around 4-5 GPa. As the\ntransition pressure is very close to the critical point in recent high-pressure\nelectrical transport measurements, the emergence of superconductivity in WTe2\nunder pressure is attributed to the Td-1T' structure phase transition, which\nassociates with a sliding mechanism of the TMD layers and results in a shorter\nTe-Te interlayer distance compared to the intralayer ones. These results\nhighlight the critical role of the interlayer stacking and chalcogen\ninteractions on the electronic and superconducting properties of multilayered\nTMDs under hydrostatic strain environments."
    },
    {
        "anchor": "Electrical resistivity across the tricriticality in itinerant\n  ferromagnet: We investigate the discontinuous ferromagnetic phase diagram near tricritical\npoint in UCo 1-x Ru x Al compounds by electrical resistivity measurements.\nSeparation of phases in UCo 0.995 Ru 0.005 Al at ambient pressure and in UCo\n0.990 Ru 0.010 Al at pressure of 0.2 GPa and disappearance of ferromagnetism at\n0.4 GPa is confirmed. The exponent of temperature dependence of electrical\nresistivity implies change from Fermi liquid behavior to non-Fermi liquid at\n0.2 GPa and reaches minimum at 0.4 GPa. Our results are compared to results\nobtained on the pure UCoAl and explanation for different exponents is given.",
        "positive": "Crossover between bulk and interface photovoltaic mechanisms in\n  ferroelectric vertical heterostructure: Bulk photovoltaic (BPVE) effect in crystals lacking inversion symmetry offers\ngreat potential for optoelectronic applications due to its unique properties\nsuch as above bandgap photovoltage and switchable photocurrent. Because of\ntheir large spontaneous polarizations, ferroelectric materials are ideal\nplatforms for studying BPVE. However, identifying the origin of experimentally\nobserved photovoltaic response is often challenging due to the entanglement\nbetween bulk and interface effects, leading to much debate in the field. This\nissue is particularly pronounced in vertical heterostructures, where the two\neffects are comparable. Here we report a crossover between bulk- and\ninterface-dominant response in vertical BiFeO3 heterostructures when changing\nthe photon energy. We show that well above-bandgap excitation leads to bulk\nphotovoltaic response, but band-edge excitation requires interface band bending\nto separate the photocarriers. Our findings not only help to clarify\ncontradicting reports in the literature, but also lay the ground for a deeper\nunderstanding of ferroelectric photovoltaic effect and its applications in\nvarious devices."
    },
    {
        "anchor": "Electrically Enhanced Free Dendrite Growth in Polar and Non-polar\n  Systems: We describe the electrically enhanced growth of needle crystals from the\nvapor phase, for which there exists a morphological instability above a\nthreshold applied potential. Our improved theoretical treatment of this\nphenomenon shows that the instability is present in both polar and non-polar\nsystems, and we provide an extension of solvability theory to include\nelectrical effects. We present extensive experimental data for ice needle\ngrowth above the electrical threshold, where at $T=-5$C high-velocity\nshape-preserving growth is observed. These data indicate that the needle tip\nassumes an effective radius} $R^{\\ast}$ which is nearly independent of both\nsupersaturation and the applied potential. The small scale of $R^{\\ast}$ and\nits response to chemical additives suggest that the needle growth rate is being\nlimited primarily by structural instabilities, possibly related to surface\nmelting. We also demonstrate experimentally that non-polar systems exhibit this\nsame electrically induced morphological instability.",
        "positive": "Single-site orthogonalization for first-principles computations of\n  exchange coupling constants: For accurate first-principles computations of exchange coupling constants\n$J_{ij}$ by the Liechtenstein method with localized basis sets, we developed a\nscheme using the single-site orthogonalization (SO). In contrast to the\nnon-orthogonal (NO) scheme, where the basis set is used to compute $J_{ij}$\nwithout modification, and the L\\\"owdin orthogonalization (LO) scheme, the SO\nscheme exhibits much less dependence of $J_{ij}$ on the choice of the basis\nset. The SO scheme achieves convergence of $J_{ij}$ for bcc Fe, hcp Co, and fcc\nNi with an increase in the number of the basis set, while the NO and LO schemes\nresult in the fluctuation depending on the basis set. This improvement by the\nSO scheme is attributed to the removal of orbital overlaps with avoiding\nill-defined single-site effective potentials. We further improve the SO scheme\nby introducing appropriate spin population, so that the SO with spin-population\nscaling (SOS) scheme can provide converged Curie temperatures for transition\nmetals. Moreover, negative values of $J_{ij}$ for dhcp Nd and rhombohedral Sm\nobtained by the SOS scheme can coincide with the experimentally-found magnetic\norder that cannot be reproduced by positive sets of $J_{ij}$."
    },
    {
        "anchor": "Effective medium theory of left-handed materials: We analyze the transmission and reflection data obtained through transfer\nmatrix calculations on metamaterials of finite lengths, to determine their\neffective permittivity and permeability. Our study concerns metamaterial\nstructures composed of periodic arrangements of wires, cut-wires, split ring\nresonators (SRRs), closed-SRRs, and both wires and SRRs. We find that the SRRs\nhave a strong electric response, equivalent to that of cut-wires, which\ndominates the behavior of left-handed materials (LHM). Analytical expressions\nfor the effective parameters of the different structures are given, which can\nbe used to explain the transmission characteristics of LHMs. Of particular\nrelevance is the criterion introduced by our studies to identify if an\nexperimental transmission peak is left- or right-handed.",
        "positive": "Probing Molecular Ordering in the Nematic Phases of para-Linked\n  Bimesogen Dimers through NMR Studies of Flexible Prochiral Solutes: The quadrupolar splittings of perdeuteriated n-decane dissolved in nematic\nphases formed by mesogenic dimers of the CBnCB series, for n=7,9,10,11 are\nmeasured throughout the entire temperature range of these phases. The results\nof the measurements, are reported together with related measurements using the\ncommon nematic phase of 5CB as a solvent for n-decane. The data obtained from\nthe $^{13}$C spectra of the cyanobiphenyl mesogenic units of the monomeric and\ndimeric solvent molecules yield the order parameter of those units. The\ninformation obtained from this set of experiments is used to elucidate the\nstructure of the low temperature (N$_X$) and the high temperature (N) nematic\nphases of CBnCB dimers with n=7,9,11. The polar twisted nematic (N$_{PT}$)\nmodel is found to provide a consistent description not only of these\nmeasurements, but also of NMR measurements previously reported in the\nliterature for these phases. These findings suggest that the high temperature\nnematic (N) is not a common, locally uniaxial and apolar nematic, but rather a\nnematic phase consisting of N$_{PT}$ clusters. The twist-bend (N$_{TB}$) model,\noften identified with the N$_X$ phase, is shown to be inadequate to account\neven qualitatively for crucial features of the experimental findings."
    },
    {
        "anchor": "Spectroscopic realization of large surface gap in a doped magnetic\n  topological insulator: Realization of the quantum anomalous Hall effect and axion electrodynamics in\ntopological materials are among the paradigmatic phenomena in condensed matter\nphysics. Recently, signatures of both phases are observed to exist in thin\nfilms of MnBi$_2$Te$_4$, a stoichiometric antiferromagnetic topological\ninsulator. Direct evidence of the bulk topological magnetoelectric response in\nan axion insulator requires an energy gap at its topological surface state\n(TSS). However, independent spectroscopic experiments revealed that such a\nsurface gap is absent, or much smaller than previously thought, in\nMnBi$_2$Te$_4$. Here, we utilize angle resolved photoemission spectroscopy and\ndensity functional theory calculations to demonstrate that a sizable TSS gap\nunexpectedly exists in Sb-doped MnBi$_2$Te$_4$. This gap is found to be\ntopologically nontrivial, insensitive to the bulk\nantiferromagnetic-paramagnetic transition, while enlarges along with increasing\nSb concentration. Our work shows that Mn(Bi$_{1-x}$Sb$_x$)$_2$Te$_4$ is a\npotential platform to observe the key features of the high-temperature axion\ninsulator state, such as the topological magnetoelectric responses and\nhalf-integer quantum Hall effects.",
        "positive": "The physical studies and interaction with anti-apoptotic proteins of\n  2-(bis(cyanomethyl)amino)-2-oxoethyl methacrylate molecule: In this work 2-(bis(cyanomethyl)amino)-2-oxoethyl methacrylate (CMA2OEM)\nmolecule has been characterized theoretically. First, the potential energy\nsurface has been calculated to find the lowest energy state of the molecule.\nAfter the most stable state of the molecule, Mulliken atomic charge and\nnonlinear-optical properties were investigated. Also in the study, binding\nposes of CMA2OEM molecule and anti-apoptotic proteins, such as BCL-2, BCL-w,\nMCL-1, AKT1 and BRAF were investigated. The molecular docking results showed\nthat the most stable complex was obtained with this molecule and BRAF protein.\nThe molecular docking results showed that the most stable complex was obtained\nwith this molecule and serine/threonine-protein kinase protein. This study\nsuggested that molecular docking approach may be a potential tool to identify\nthe hydrogen bond interactions in order to treat a disease. Finally, this new\nligand could pave the way to experimental studies."
    },
    {
        "anchor": "A universal relationship between magnetization and local structure\n  changes below the ferromagnetic transition in La_{1-x}Ca_xMnO_3; evidence for\n  magnetic dimers: We present extensive X-ray Absorption Fine Structure (XAFS) measurements on\nLa_{1-x}Ca_xMnO_3 as a function of B-field (to 11T) and Ca concentration, x\n(21-45%). These results reveal local structure changes (associated with polaron\nformation) that depend only on the magnetization for a given sample,\nirrespective of whether the magnetization is achieved through a decrease in\ntemperature or an applied magnetic field. Furthermore, the relationship between\nlocal structure and magnetization depends on the hole doping. A model is\nproposed in which a filamentary magnetization initially develops via the\naggregation of pairs of Mn atoms involving a hole and an electron site. These\npairs have little distortion and it is likely that they pre-form at\ntemperatures above T_c.",
        "positive": "Origin and the role of device physics in the magnetic field effect in\n  organic semiconductor devices: A small magnetic field (~30 mT) can effectively modulate the\nelectroluminescence, conductance and/or photocurrent of organic semiconductor\nbased devices, up to 10% at room temperature. This organic magnetic field\neffect (OMFE) is one of the most unusual phenomena of both organic electronics\nand, more basically, magnetism, since all device components are nonmagnetic.\nHowever, in spite of latest surge of research interest, its underlying\nmechanism is still hotly debated. Here we experimentally identify that the\nmagnetic field induced increase of intersystem crossing rate (between either\nexcitons or polaron pairs), and decrease of triplet exciton-polaron quenching\nrate are responsible for the observed OMFEs. The diversity of observed OMFE\nresults, such as sign change and operating condition dependence, originates\nfrom the difference of devices physics."
    },
    {
        "anchor": "Interface chemical and electronic properties of LaAlO3/SrVO3\n  heterostructures: We have studied the chemical and electronic properties of LaAlO3/SrVO3\nultrathin films by combining hard x-ray photoemission spectroscopy and\ntransport measurements. We compare single SrVO3 (SVO) ultrathin films and SrVO3\nburied below a polar LaAlO3 (LAO) thin layer, both epitaxially grown on SrTiO3.\nWhile ultrathin films (4 unit cells) of SVO do show insulating behavior over\nthe entire temperature range, the LAO/SVO interface has a resistivity minimum\nat 250 K. When increasing the SVO layer thickness, the minimum is observed to\nshift to higher temperatures, but the resistivity stays always smaller than\nthat of comparable SVO single films. Hard x-ray photoemission spectroscopy\nreveals a surface or interface related V5+ component in the V 2p spectra for\nSVO films and LAO/SVO heterostructures, respectively, attributed to a strongly\noxidized component. This chemical reconstruction is weaker in LAO/SVO\nheterostructures compared to single SVO films. We show that this dead layer in\nSVO ultrathin films has to be considered when the film thickness reaches the\nfew unit-cells limit and propose solutions on how to prevent this detrimental\neffect.",
        "positive": "Properties of random sequential adsorption of generalized dimers: Saturated random packing of particles built of two identical, relatively\nshifted spheres in two and three dimensional flat and homogeneous space was\nstudied numerically using random sequential adsorption algorithm. The shift\nbetween centers of spheres varied from 0.0 to 8.0 sphere diameters. Numerical\nsimulations allowed determine random sequential adsorption kinetics, saturated\nrandom coverage ratio as well as available surface function and density\nautocorrelation function."
    },
    {
        "anchor": "Strain-induced magnetic phase transition in SrCoO$_{3-\u03b4}$ thin\n  films: It has been well established that both in bulk at ambient pressure and for\nfilms under modest strains, cubic SrCoO$_{3-\\delta}$ ($\\delta < 0.2$) is a\nferromagnetic metal. Recent theoretical work, however, indicates that a\nmagnetic phase transition to an antiferromagnetic structure could occur under\nlarge strain accompanied by a metal-insulator transition. We have observed a\nstrain-induced ferromagnetic to antiferromagnetic phase transition in\nSrCoO$_{3-\\delta}$ films grown on DyScO$_3$ substrates, which provide a large\ntensile epitaxial strain, as compared to ferromagnetic films under lower\ntensile strain on SrTiO$_3$ substrates. Magnetometry results demonstrate the\nexistence of antiferromagnetic spin correlations and neutron diffraction\nexperiments provide a direct evidence for a G-type antiferromagnetic structure\nwith Ne\\'el temperatures between $T_N \\sim 135\\,\\pm\\,10\\,K$ and $\\sim\n325\\,\\pm\\,10\\,K$ depending on the oxygen content of the samples. Therefore, our\ndata experimentally confirm the predicted strain-induced magnetic phase\ntransition to an antiferromagnetic state for SrCoO$_{3-\\delta}$ thin films\nunder large epitaxial strain.",
        "positive": "Rydberg excitons in the presence of an ultralow-density electron-hole\n  plasma: We use two-color pump-probe spectroscopy to study Rydberg excitons in Cu$_2$O\nin the presence of free carriers injected by above-band-gap excitation. Already\nat plasma densities $\\rho_\\text{eh}$ below one hundredth electron-hole pair per\n\\textmu m$^{3}$, the Rydberg exciton absorption lines are bleached while their\nenergies remain constant, until they finally disappear, starting from the\nhighest observed principal quantum number $n_\\text{max}$. As confirmed by\ncalculations, the band gap is reduced by many-particle effects caused by free\ncarriers scaling as $\\rho_\\text{eh}^{1/2}$. An exciton line looses oscillator\nstrength when the band edge approaches the exciton energy vanishing completely\nat the crossing point. We quantitatively describe this plasma blockade by\nintroducing an effective Bohr radius that determines the energy distance to the\nshifted band edge. In combination with the negligible associated decoherence\nthis opens the possibility to control the Rydberg exciton absorption through\nthe plasma-induced band gap modulation."
    },
    {
        "anchor": "A novel artificial condensed matter lattice and a new platform for\n  one-dimensional topological phases: Engineered lattices in condensed matter physics, such as cold atom optical\nlattices or photonic crystals, can have fundamentally different properties from\nnaturally-occurring electronic crystals. Here, we report a novel type of\nartificial quantum matter lattice. Our lattice is a multilayer heterostructure\nbuilt from alternating thin films of topological and trivial insulators. Each\ninterface within the heterostructure hosts a set of topologically-protected\ninterface states, and by making the layers sufficiently thin, we demonstrate\nfor the first time a hybridization of interface states across layers. In this\nway, our heterostructure forms an emergent atomic chain, where the interfaces\nact as lattice sites and the interface states act as atomic orbitals, as seen\nfrom our measurements by angle-resolved photoemission spectroscopy (ARPES). By\nchanging the composition of the heterostructure, we can directly control\nhopping between lattice sites. We realize a topological and a trivial phase in\nour superlattice band structure. We argue that the superlattice may be\ncharacterized in a significant way by a one-dimensional topological invariant,\nclosely related to the invariant of the Su-Schrieffer-Heeger model. Our\ntopological insulator heterostructure demonstrates a novel experimental\nplatform where we can engineer band structures by directly controlling how\nelectrons hop between lattice sites.",
        "positive": "Analysis of external and internal disorder to understand band-like\n  transport in n-type organic semiconductors: Charge transport in organic semiconductors is notoriously extremely sensitive\nto the presence of disorder, both internal and external (i.e. related to the\ninteractions with the dielectric layer), especially for n-type materials.\nInternal dynamic disorder stems from large thermal fluctuations both in\nintermolecular transfer integrals and (molecular) site energies in weakly\ninteracting van der Waals solids and sources transient localization of the\ncharge carriers. The molecular vibrations that drive transient localization\ntypically operate at low-frequency (< a-few-hundred cm-1), which renders it\ndifficult to assess them experimentally. Hitherto, this has prevented the\nidentification of clear molecular design rules to control and reduce dynamic\ndisorder. In addition, the disorder can also be external, being controlled by\nthe gate insulator dielectric properties. Here we report on a comprehensive\nstudy of charge transport in two closely related n-type molecular organic\nsemiconductors using a combination of temperature-dependent inelastic neutron\nscattering and photoelectron spectroscopy corroborated by electrical\nmeasurements, theory and simulations. We provide unambiguous evidence that ad\nhoc molecular design enables to free the electron charge carriers from both\ninternal and external disorder to ultimately reach band-like electron\ntransport."
    },
    {
        "anchor": "Correlation-driven threefold topological phase transition in monolayer\n  $\\mathrm{OsBr_2}$: Spin-orbit coupling (SOC) combined with electronic correlation can induce\ntopological phase transition, producing novel electronic states. Here, we\ninvestigate the impact of SOC combined with correlation effects on physical\nproperties of monolayer $\\mathrm{OsBr_2}$, based on first-principles\ncalculations with generalized gradient approximation plus $U$ (GGA+$U$)\napproach. With intrinsic out-of-plane magnetic anisotropy, $\\mathrm{OsBr_2}$\nundergoes threefold topological phase transition with increasing $U$, and\nvalley-polarized quantum anomalous Hall insulator (VQAHI) to half-valley-metal\n(HVM) to ferrovalley insulator (FVI) to HVM to VQAHI to HVM to FVI transitions\ncan be induced. These topological phase transitions are connected with\nsign-reversible Berry curvature and band inversion between\n$d_{xy}$/$d_{x^2-y^2}$ and $d_{z^2}$ orbitals. Due to $\\bar{6}m2$ symmetry,\npiezoelectric polarization of $\\mathrm{OsBr_2}$ is confined along the in-plane\narmchair direction, and only one $d_{11}$ is independent. For a given material,\nthe correlation strength should be fixed, and $\\mathrm{OsBr_2}$ may be a\npiezoelectric VQAHI (PVQAHI), piezoelectric HVM (PHVM) or piezoelectric FVI\n(PFVI). The valley polarization can be flipped by reversing the magnetization\nof Os atoms, and the ferrovalley (FV) and nontrivial topological properties\nwill be suppressed by manipulating out-of-plane magnetization to in-plane one.\nIn considered reasonable $U$ range, the estimated Curie temperatures all are\nhigher than room temperature. Our findings provide a comprehensive\nunderstanding on possible electronic states of $\\mathrm{OsBr_2}$, and confirm\nthat strong SOC combined with electronic correlation can induce multiple\nquantum phase transition.",
        "positive": "Strain-induced electronic phase transition and strong enhancement of\n  thermopower of TiS2: Using first principles density functional theory calculations, we show a\nsemimetal to semiconducting electronic phase transition for bulk TiS 2 by\napplying uniform biaxial tensile strain. This electronic phase transition is\ntriggered by charge transfer from Ti to S, which eventually reduces the overlap\nbetween Ti-(d) and S-(p) orbitals. The electronic transport calculations show a\nlarge anisotropy in electrical conductivity and thermopower, which is due to\nthe difference in the effective masses along the in-plane and out of plane\ndirections. Strain induced opening of band gap together with changes in\ndispersion of bands lead to three-fold enhancement in thermopower for both p-\nand n-type TiS2 . We further demonstrate that the uniform tensile strain, which\nenhances the thermoelectric performance, can be achieved by doping TiS2 with\nlarger iso-electronic elements such as Zr or Hf at Ti sites."
    },
    {
        "anchor": "Multi-Terminal Memtransistors from Polycrystalline Monolayer MoS2: In the last decade, a 2-terminal passive circuit element called a memristor\nhas been developed for non-volatile resistive random access memory and has more\nrecently shown promise for neuromorphic computing. Compared to flash memory,\nmemristors have higher endurance, multi-bit data storage, and faster read/write\ntimes. However, although 2-terminal memristors have demonstrated basic neural\nfunctions, synapses in the human brain outnumber neurons by more than a factor\nof 1000, which implies that multiterminal memristors are needed to perform\ncomplex functions such as heterosynaptic plasticity. Previous attempts to move\nbeyond 2-terminal memristors include the 3-terminal Widrow-Hoff memistor and\nfield-effect transistors with nanoionic gates or floating gates, albeit without\nmemristive switching in the transistor. Here, we report the scalable\nexperimental realization of a multi-terminal hybrid memristor and transistor\n(i.e., memtransistor) using polycrystalline monolayer MoS2. Two-dimensional\n(2D) MoS2 memtransistors show gate tunability in individual states by 4 orders\nof magnitude in addition to large switching ratios with high cycling endurance\nand long-term retention of states. In addition to conventional neural learning\nbehavior of long-term potentiation/depression, 6-terminal MoS2 memtransistors\npossess gate-tunable heterosynaptic functionality that is not achievable using\n2-terminal memristors. For example, the conductance between a pair of two\nfloating electrodes (pre-synaptic and post-synaptic neurons) is varied by 10X\nby applying voltage pulses to modulatory terminals. In situ scanning probe\nmicroscopy, cryogenic charge transport measurements, and device modeling reveal\nthat bias-induced MoS2 defect motion drives resistive switching by dynamically\nvarying Schottky barrier heights.",
        "positive": "Enhancement and tuning of the defect-induced electroluminescence of ZnO\n  mesoporous layers in the visible range: We show a way to pattern the visible electroluminescence of\nsolution-processed mesoporous ZnO layers. Our approach consists in locally\nchanging the nanoscale morphology of the coated ZnO layers by patterning the\nunderlying surface with thin metallic patches. Above the metal, the ZnO film is\norganized in clusters that enhance its defect-induced electroluminescence. The\nresulting emission occurs over a large continuum of wavelengths in the visible\nand near-infrared range. This broad emission continuum is filtered by thin film\ninterferences that develop within the device, making it possible to fabricate\nLEDs with different colours by adjusting the thickness of their transparent\nelectrode. When the metallic patterns used to change the morphology of the ZnO\nlayer reach sub-micron dimensions, additional plasmonic effects arise,\nproviding extra degrees of freedom to tune the colour and polarization of the\nemitted photons."
    },
    {
        "anchor": "Control of the metal-insulator transition in NdNiO$_3$ thin films\n  through the interplay between structural and electronic properties: Heteroepitaxy offers a new type of control mechanism for the crystal\nstructure, the electronic correlations, and thus the functional properties of\ntransition-metal oxides. Here, we combine electrical transport measurements,\nhigh-resolution scanning transmission electron microscopy (STEM), and density\nfunctional theory (DFT) to investigate the evolution of the metal-to-insulator\ntransition (MIT) in NdNiO$_3$ films as a function of film thickness and\nNdGaO$_3$ substrate crystallographic orientation. We find that for two\ndifferent substrate facets, orthorhombic (101) and (011), modifications of the\nNiO$_6$ octahedral network are key for tuning the transition temperature\n$T_{\\text{MIT}}$ over a wide temperature range. A comparison of films of\nidentical thickness reveals that growth on [101]-oriented substrates generally\nresults in a higher $T_{\\text{MIT}}$, which can be attributed to an enhanced\nbond-disproportionation as revealed by the DFT+$U$ calculations, and a tendency\nof [011]-oriented films to formation of structural defects and stabilization of\nnon-equilibrium phases. Our results provide insights into the\nstructure-property relationship of a correlated electron system and its\nevolution at microscopic length scales and give new perspectives for the\nepitaxial control of macroscopic phases in metal-oxide heterostructures.",
        "positive": "Kramers nodal lines and Weyl fermions in SmAlSi: Kramers nodal lines (KNLs) have recently been proposed theoretically as a\nspecial type of Weyl line degeneracy connecting time-reversal invariant\nmomenta. KNLs are robust to spin orbit coupling and are inherent to all\nnon-centrosymmetric achiral crystal structures, leading to unusual spin,\nmagneto-electric, and optical properties. However, their existence in in real\nquantum materials has not been experimentally established. Here we gather the\nexperimental evidence pointing at the presence of KNLs in SmAlSi, a\nnon-centrosymmetric metal that develops incommensurate spin density wave order\nat low temperature. Using angle-resolved photoemission spectroscopy, density\nfunctional theory calculations, and magneto-transport methods, we provide\nevidence suggesting the presence of KNLs, together with observing Weyl fermions\nunder the broken inversion symmetry in the paramagnetic phase of SmAlSi. We\ndiscuss the nesting possibilities regarding the emergent magnetic orders in\nSmAlSi. Our results provide a solid basis of experimental observations for\nexploring correlated topology in SmAlSi."
    },
    {
        "anchor": "Measurements of Ice Crystal Growth Rates in Air at -5C and -10C: We present experiments investigating the growth of ice crystals from water\nvapor in air using a free-fall convection chamber. We measured growth rates at\ntemperatures of -5 C and -10 C as a function of supersaturation at an air\npressure near one bar. We compared our data with numerical models of\ndiffusion-limited growth based on cellular automata to extract surface growth\nparameters at different temperatures and supersaturations. From these\ninvestigations we hope to better understand the surface molecular dynamics that\ndetermine crystal growth rates and morphologies.",
        "positive": "Optical Properties of III-Mn-V Ferromagnetic Semiconductors: We review the first decade of extensive optical studies of ferromagnetic,\nIII-Mn-V diluted magnetic semiconductors. Mn introduces holes and local moments\nto the III-V host, which can result in carrier mediated ferromagnetism in these\ndisordered semiconductors. Spectroscopic experiments provide direct access to\nthe strength and nature of the exchange between holes and local moments; the\ndegree of itineracy of the carriers; and the evolution of the states at the\nFermi energy with doping. Taken together, diversity of optical methods reveal\nthat Mn is an unconventional dopant, in that the metal to insulator transition\nis governed by the strength of the hybridization between Mn and its p-nictogen\nneighbor. The interplay between the optical, electronic and magnetic properties\nof III-Mn-V magnetic semiconductors is of fundamental interest and may enable\nfuture spin-optoelectronic devices."
    },
    {
        "anchor": "Transient terahertz photoconductivity measurements of minority-carrier\n  lifetime in tin sulfide thin films: Advanced metrology for an early-stage\n  photovoltaic material: Materials research with a focus on enhancing the minority-carrier lifetime of\nthe light-absorbing semiconductor is key to advancing solar energy technology\nfor both early-stage and mature material platforms alike. Tin sulfide (SnS) is\nan absorber material with several clear advantages for manufacturing and\ndeployment, but the record power conversion efficiency remains below 5%. We\nreport measurements of bulk and interface minority-carrier recombination rates\nin SnS thin films using optical-pump, terahertz (THz)-probe transient\nphotoconductivity (TPC) measurements. Post-growth thermal annealing in H_2S gas\nincreases the minority-carrier lifetime, and oxidation of the surface reduces\nthe surface recombination velocity. However, the minority-carrier lifetime\nremains below 100 ps for all tested combinations of growth technique and\npost-growth processing. Significant improvement in SnS solar cell performance\nwill hinge on finding and mitigating as-yet-unknown recombination-active\ndefects. We describe in detail our methodology for TPC experiments, and we\nshare our data analysis routines as freely-available software.",
        "positive": "Anharmonicity of the antiferrodistortive soft mode in barium zirconate\n  BaZrO$_3$: Barium zirconate (BaZrO$_3$) is one of the very few perovskites that is\nclaimed to retain an average cubic structure down to \\SI{0}{\\K}, while being\nenergetically very close to an antiferrodistortive phase obtained by\ncondensation of a soft phonon mode at the R point of the Brillouin zone\nboundary. In this work, we report a combined experimental and theoretical study\nof the temperature dependence of this soft phonon mode. Inelastic neutron and\nx-ray scattering measurements on single crystals show that it softens\nsubstantially from \\SI{9.4}{\\meV} at room temperature to \\SI{5.6}{\\meV} at\n\\SI{2}{\\K}. In contrast, the acoustic mode at the same R point is nearly\ntemperature independent. The effect of the anharmonicity on the lattice\ndynamics is investigated non-perturbatively using direct dynamic simulations as\nwell as a first-principles based self-consistent phonon theory, including\nquantum fluctuations of the atomic motion. By adding cubic and quartic\nanharmonic force constants, quantitative agreement with the neutron data for\nthe temperature dependence of the antiferrodistortive mode is obtained. The\nquantum fluctuations of the atomic motion are found to be important to obtain\nthe proper temperature dependence at low temperatures. The mean squared\ndisplacements of the different atoms are determined as function of temperature\nand are shown to be consistent with available experimental data. Adding\nanharmonicity to the computed fluctuations of the Ba-O distances also improves\nthe comparison with available EXAFS data at \\SI{300}{\\K}."
    },
    {
        "anchor": "Bending modes, elastic constants and mechanical stability of graphitic\n  systems: The thermodynamic and mechanical properties of graphitic systems are strongly\ndependent on the shear elastic constant C44. Using state-of-the-art density\nfunctional calculations, we provide the first complete determination of their\nelastic constants and exfoliation energies. We show that stacking\nmisorientations lead to a severe lowering of C44 of at least one order of\nmagnitude. The lower exfoliation energy and the lower C44 (more bending modes)\nsuggest that flakes with random stacking should be easier to exfoliate than the\nones with perfect or rhombohedral stacking. We also predict ultralow friction\nbehaviour in turbostratic graphitic systems.",
        "positive": "Kohn Anomalies and Electron-Phonon Interaction in Graphite: We demonstrate that graphite phonon dispersions have two Kohn anomalies at\nthe Gamma-E_2g and K-A'1 modes. The anomalies are revealed by two sharp kinks.\nBy an exact analytic derivation, we show that the slope of these kinks is\nproportional to the square of the electron-phonon coupling (EPC). Thus, we can\ndirectly measure the EPC from the experimental dispersions. The Gamma-E_2g and\nK-A'1 EPCs are particularly large, whilst they are negligible for all the other\nmodes at Gamma and K."
    },
    {
        "anchor": "Acoustic Cyclotron Resonance and Giant High Frequency Magnetoacoustic\n  Oscillations in Metals with Locally Flattened Fermi Surface: We consider the effect of local flattening on the Fermi surface (FS) of a\nmetal upon geometric oscillations of the velocity and attenuation of ultrasonic\nwaves in the neighborhood of the acoustic cyclotron resonance. It is shown that\nsuch peculiarities of the local geometry of the FS can lead to a significant\nenhancement of both cyclotron resonance and geometric oscillations.\nCharacteristic features of the coupling of ultrasound to shortwave cyclotron\nwaves arising due to the local flattening of the FS are analyzed.\n  PACS numbers 71.18.+y; 72.15.Gd; 72.15.-v",
        "positive": "Mechanism of Spin Scattering in Ta investigated by Scanning Inverse Spin\n  Hall Effect Meters: In this work, a scanning inverse spin Hall effect measurement system based on\na shorted coaxial resonator has been built, which provides a high throughput\nmethod to characterize spin transport properties. The spin diffusion length of\nTa at room temperature is determined via automatic measurements of Py/Ta\nbilayer strips with different thicknesses of Ta. The results show that the spin\ndiffusion length is about 4 nm with a conductivity of about 7.5E5\n{\\Omega}-1m-1, which leads to the conclusion that the intrinsic mechanism of\nspin relaxation of Ta is the Elliott-Yafet interactions. The setup developed in\nthis work provides a convenient, efficient, and non-destructive way to obtain\nthe spin and electron transportation characteristics of the spintronic\nmaterials, which will fertilize this community by developing new materials and\nfiguring out their mechanism."
    },
    {
        "anchor": "Magneto-absorption spectra of hydrogen-like yellow exciton series in\n  cuprous oxide: excitons in strong magnetic fields: We study the absorption spectra of the yellow excitons in Cu$_2$O in high\nmagnetic fields using polarization-resolved optical absorption measurements\nwith a high frequency resolution. We show that the symmetry of the yellow\nexciton results in unusual selection rules for the optical absorption of\npolarized light and that the mixing of ortho- and para- excitons in magnetic\nfield is important. Our calculation of the energies of the yellow exciton\nseries in an arbitrary magnetic field gives an excellent fit to experimental\ndata and allows us to understand the complex structure of excitonic levels and\ntheir magnetic field dependence, which resolves the old-standing disagreement\nbetween the results of optical absorption and cyclotron resonance measurements.",
        "positive": "Quasi-static and Dynamic Behavior of Additively Manufactured Metallic\n  Lattice Cylinders: Lattice structures have tailorable mechanical properties which allows them to\nexhibit superior mechanical properties (per unit weight) beyond what is\nachievable through natural materials. In this paper, quasi-static and dynamic\nbehavior of additively manufactured stainless steel lattice cylinders is\nstudied. Cylindrical samples with internal lattice structure are fabricated by\na laser powder bed fusion system. Equivalent hollow cylindrical samples with\nthe same length, outer diameter, and mass (larger wall thickness) are also\nfabricated. Split Hopkinson bar is used to study the behavior of the specimens\nunder high strain rate loading. It is observed that lattice cylinders reduce\nthe transmitted wave amplitude up to about 21% compared to their equivalent\nhollow cylinders. However, the lower transmitted wave energy in lattice\ncylinders comes at the expense of a greater reduction in their stiffness, when\ncompared to their equivalent hollow cylinder. In addition, it is observed that\nincreasing the loading rate by five orders of magnitude leads to up to about\n36% increase in the peak force that the lattice cylinder can carry, which is\nattributed to strain rate hardening effect in the bulk stainless steel\nmaterial. Finite element simulations of the specimens under dynamic loads are\nperformed to study the effect of strain rate hardening, thermal softening, and\nthe failure mode on dynamic behavior of the specimens. Numerical results are\ncompared with experimental data and good qualitative agreement is observed."
    },
    {
        "anchor": "Crystal Thermal Transport in Altermagnetic RuO2: We demonstrate the emergence of a pronounced thermal transport in the\nrecently discovered class of magnetic materials-altermagnets. From symmetry\narguments and first-principles calculations performed for the showcase\naltermagnet, RuO2, we uncover that crystal Nernst and crystal thermal Hall\neffects in this material are very large and strongly anisotropic with respect\nto the Neel vector. We find the large crystal thermal transport to originate\nfrom three sources of Berry's curvature in momentum space: the Weyl fermions\ndue to crossings between well-separated bands, the strong spin-flip pseudonodal\nsurfaces, and the weak spin-flip ladder transitions, defined by transitions\namong very weakly spin-split states of similar dispersion crossing the Fermi\nsurface. Moreover, we reveal that the anomalous thermal and electrical\ntransport coefficients in RuO2 are linked by an extended Wiedemann-Franz law in\na temperature range much wider than expected for conventional magnets. Our\nresults suggest that altermagnets may assume a leading role in realizing\nconcepts in spin caloritronics not achievable with ferromagnets or\nantiferromagnets.",
        "positive": "Intermittency in crystal plasticity informed by lattice symmetry: We develop a nonlinear, three-dimensional phase field model for crystal\nplasticity which accounts for the infinite and discrete symmetry group G of the\nunderlying periodic lattice. This generates a complex energy landscape with\ncountably-many G-related wells in strain space, whereon the material evolves by\nenergy minimization under the loading through spontaneous slip processes\ninducing the creation and motion of dislocations without the need of auxiliary\nhypotheses. Multiple slips may be activated simultaneously, in domains\nseparated by a priori unknown free boundaries. The wells visited by the strain\nat each position and time, are tracked by the evolution of a G-valued discrete\nplastic map, whose non-compatible discontinuities identify lattice\ndislocations. The main effects in the plasticity of crystalline materials at\nmicroscopic scales emerge in this framework, including the long-range elastic\nfields of possibly interacting dislocations, lattice friction, hardening,\nband-like vs. complex spatial distributions of dislocations. The main results\nconcern the scale-free intermittency of the flow, with power-law exponents for\nthe slip avalanche statistics which are significantly affected by the symmetry\nand the compatibility properties of the activated fundamental shears."
    },
    {
        "anchor": "Nuclear Magnetic Resonance Studies of delta-Stabilized Plutonium: Nuclear Magnetic Resonance studies of Ga stabilized delta-Pu reveal detailed\ninformation about the local distortions surrounding the Ga impurities as well\nas provides information about the local spin fluctuations experienced by the Ga\nnuclei. The Ga NMR spectrum is inhomogeneously broadened by a distribution of\nlocal electric field gradients (EFGs), which indicates that the Ga experiences\nlocal distortions from cubic symmetry. The Knight shift and spin lattice\nrelaxation rate indicate that the Ga is dominantly coupled to the Fermi surface\nvia core polarization, and is inconsistent with magnetic order or low frequency\nspin correlations.",
        "positive": "The control of iron oxidation state during FeO and olivine crystal\n  growth: Crystal growth experiments (micro-pulling down or Czochralski methods,\nrespectively) and DTA/TG measurements with Fe2+ containing olivines\n(fayalite--forsterite solid solution) and with FeO (wustite) are performed. For\nboth substances the oxygen partial pressure p_O2 of the growth atmosphere had\nto be adjusted within the stability region of Fe2+ for all temperatures ranging\nfrom room temperature to the melting point. The formation of Fe3+ (Fe3O4,\nFe2O3) had to be avoided. The adjustment of p_O2 could be obtained by a mixture\nof argon, carbon dioxide and carbon monoxide. Thermodynamic equilibrium\ncalculations show, that mixtures of an inert gas (e.g. argon) with another gas\nor gas mixture that supplies oxygen at elevated temperature (e.g. CO2/CO) are\nsuperior to the use of inert gases with constant oxygen admixture. The reason\nis that the Ar/CO2/CO mixture adjusts its oxygen concentration with temperature\nin a way similar to that needed for the stabilization of Fe2+."
    },
    {
        "anchor": "Surface step effects on Si (100) under uniaxial tensile stress, by\n  atomistic calculations: This paper reports a study of the influence of the step at a silicon surface\nunder an uniaxial tensile stress, using an empirical potential. Our aim was to\nfind conditions leading to nucleation of dislocations from the step. We\nobtained that no dislocations could be generated with such conditions. This\nbehaviour, different from the one predicted for metals, could be attributed\neither to the covalent bonding or to the cubic diamond structure.",
        "positive": "Ordered structure of FeGe$_2$ formed during solid-phase epitaxy: Fe$_{3}$Si/Ge(Fe,Si)/Fe$_{3}$Si thin film stacks were grown by a combination\nof molecular beam epitaxy and solid phase epitaxy (Ge on Fe$_{3}$Si). The\nstacks were analyzed using electron microscopy, electron diffraction, and\nsynchrotron X-ray diffraction. The Ge(Fe,Si) films crystallize in the well\noriented, layered tetragonal structure FeGe$_{2}$ with space group P4mm. This\nkind of structure does not exist as a bulk material and is stabilized by solid\nphase epitaxy of Ge on Fe$_{3}$Si. We interpret this as an ordering phenomenon\ninduced by minimization of the elastic energy of the epitaxial film."
    },
    {
        "anchor": "Spin-phonon and magnetostriction phenomena in CaMn7O12 helimagnet probed\n  by Raman spectroscopy: In this letter we investigated the temperature-dependent Raman spectra of\nCaMn7O12 helimagnet from room temperature down to 10 K. The temperature\ndependence of the Raman mode parameters show remarkable anomalies for both\nantiferromagnetic and incommensurate transitions that this compound undergoes\nat low temperatures. The anomalies observed at the magnetic ordering transition\nindicate a spin-phonon coupling at higher-temperature magnetic transition in\nthis material, while a magnetostrinction effect at the lower-temperature\nmagnetic transition.",
        "positive": "Digital resonance tuning of high-Q/Vm silicon photonic crystal\n  nanocavities by atomic layer deposition: We propose and demonstrate the digital resonance tuning of high-Q/Vm silicon\nphotonic crystal nanocavities using a self-limiting atomic layer deposition\ntechnique. Control of resonances in discrete steps of 122 +/- 18 pm per hafnium\noxide atomic layer is achieved through this post-fabrication process, nearly\nlinear over a full 17 nm tuning range. The cavity Q is maintained in this\nperturbative process, and can reach up to its initial values of 49,000 or more.\nOur results are highly controllable, applicable to many material systems, and\nparticularly critical to matching resonances and transitions involving\nmesoscopic optical cavities."
    },
    {
        "anchor": "Statistical characterization of the yield stress of nanoparticles: Atomistic simulations are performed to study the statistical mechanical\nproperty of gold nanoparticles. It is demonstrated that the yielding behavior\nof gold nanoparticles is governed by dislocation nucleation around surface\nsteps. Since the nucleation of dislocations is an activated process with the\naid of thermal fluctuation, the yield stress at a specific temperature should\nexhibit a statistical distribution rather than a definite constant value.\nMolecular dynamics simulations reveal that the yield stress follows a Gaussian\ndistribution at a specific temperature. As the temperature increases, the mean\nvalue of yield stress decreases while the width of distribution becomes larger.\nBased on numerical analysis, the dependence of the mean yield stress on\ntemperature can be well described by a parabolic function. Present study\nilluminates the statistical features of the yielding behavior of nanostructured\nelements.",
        "positive": "Combined Spectroscopy and Electrical Characterization of\n  La:BaSnO$_\\text{3}$ Thin Films and Heterostructures: For La-doped BaSnO$_\\text{3}$ thin films grown by pulsed laser deposition, we\ncombine chemical surface characterization and electronic transport studies to\nprobe the evolution of electronic states in the band structure for different\nLa-doping content. Systematic analyses of spectroscopic data based on fitting\nthe core electron line shapes help to unravel the composition of the surface as\nwell as the dynamics associated with increasing doping. This dynamics is\nobserved with a more pronounced signature in the Sn 3d core level, which\nexhibits an increasing asymmetry to the high binding energy side of the peak\nwith increasing electron density. The present results expand the current\nunderstanding of the interplay between the doping concentration, electronic\nband structure and transport properties of epitaxial La:BaSnO$_\\text{3}$ films."
    },
    {
        "anchor": "Diffraction Patterns of Layered Close-packed Structures from Hidden\n  Markov Models: We recently derived analytical expressions for the pairwise (auto)correlation\nfunctions (CFs) between modular layers (MLs) in close-packed structures (CPSs)\nfor the wide class of stacking processes describable as hidden Markov models\n(HMMs) [Riechers \\etal, (2014), Acta Crystallogr.~A, XX 000-000]. We now use\nthese results to calculate diffraction patterns (DPs) directly from HMMs,\ndiscovering that the relationship between the HMMs and DPs is both simple and\nfundamental in nature. We show that in the limit of large crystals, the DP is a\nfunction of parameters that specify the HMM. We give three elementary but\nimportant examples that demonstrate this result, deriving expressions for the\nDP of CPSs stacked (i) independently, (ii) as infinite-Markov-order randomly\nfaulted 2H and 3C stacking structures over the entire range of growth and\ndeformation faulting probabilities, and (iii) as a HMM that models\nShockley-Frank stacking faults in 6H-SiC. While applied here to planar faulting\nin CPSs, extending the methods and results to planar disorder in other layered\nmaterials is straightforward. In this way, we effectively solve the broad\nproblem of calculating a DP---either analytically or numerically---for any\nstacking structure---ordered or disordered---where the stacking process can be\nexpressed as a HMM.",
        "positive": "Probing Single Vacancies in Black Phosphorus at the Atomic Level: Utilizing a combination of low-temperature scanning tunneling\nmicroscopy/spectroscopy (STM/STS) and electronic structure calculations, we\ncharacterize the structural and electronic properties of single atomic\nvacancies within several monolayers of the surface of black phosphorus. We\nillustrate, with experimental analysis and tight-binding calculations, that we\ncan depth profile these vacancies and assign them to specific sublattices\nwithin the unit cell. Measurements reveal that the single vacancies exhibit\nstrongly anisotropic and highly delocalized charge density, laterally extended\nup to 20 atomic unit cells. The vacancies are then studied with STS, which\nreveals in-gap resonance states near the valence band edge and a strong\np-doping of the bulk black phosphorus crystal. Finally, quasiparticle\ninterference generated near these vacancies enables the direct visualization of\nthe anisotropic band structure of black phosphorus."
    },
    {
        "anchor": "Simulation of the transient photocurrent response of polycrystalline\n  photocells based on equivalent circuit analysis: We propose an equivalent circuit representation of the photogenerated charge\nseparation and propagation in dye sensitized polycrystalline semiconductor in\ncontact with a redox electrolyte. The suggested equivalent circuit for this\ntype of photocell is based on an electrical transmission-line, and uses\ndistributed photodiode model for the semiconductor-redox electrolyte interface.\nIt was found that for small signal conditions, diodes can be replaced by\nequivalent elements, each consisting of a resistor and a capacitor connected in\nseries. The equivalent circuit also provides for Beer-Lambert characteristics\nof light absorption.\n  The simulation of the transmission line equivalent circuit, subjected to\nshort pulse illumination, allows us to reproduce the experimentally found\ndifference between the photocurrent responses of the photocell to illumination\nfrom the electrolyte side, and its response to illumination through the\nsemitransparent back electrode, to which the polycrystalline semiconductor\nlayer is attached.\n  We suggest an electrochemical model for photogenerated charge separation,\nwhereby the electrical field across the Helmholtz electrostatic double layer at\nthe polycrystalline phase - electrolyte interface separates the photogenerated\ncarriers.",
        "positive": "Probing microplasticity in small scale FCC crystals via Dynamic\n  Mechanical Analysis: In small-scale metallic systems, collective dislocation activity has been\ncorrelated with size effects in strength and with a step-like plastic response\nunder uniaxial compression and tension. Yielding and plastic flow in these\nsamples is often accompanied by the emergence of multiple dislocation\navalanches. Dislocations might be active pre-yield, but their activity\ntypically cannot be discerned because of the inherent instrumental noise in\ndetecting equipment. We apply Alternate Current (AC) load perturbations via\nDynamic Mechanical Analysis (DMA) during quasi-static uniaxial compression\nexperiments on single crystalline Cu nano-pillars with diameters of 500 nm, and\ncompute dynamic moduli at frequencies 0.1, 0.3, 1, and 10 Hz under\nprogressively higher static loads until yielding. By tracking the collective\naspects of the oscillatory stress-strain-time series in multiple samples, we\nobserve an evolving dissipative component of the dislocation network response\nthat signifies the transition from elastic behavior to dislocation avalanches\nin the globally pre-yield regime. We postulate that microplasticity, which is\nassociated with the combination of dislocation avalanches and slow viscoplastic\nrelaxations, is the cause of the dependency of dynamic modulus on the driving\nrate and the quasi-static stress. We construct a continuum mesoscopic\ndislocation dynamics model to compute the frequency response of stress over\nstrain and obtain a consistent agreement with experimental observations. The\nresults of our experiments and simulations present a pathway to discern and\nquantify correlated dislocation activity in the pre-yield regime of deforming\ncrystals."
    },
    {
        "anchor": "Predictability as a probe of manifest and latent physics: The case of\n  atomic scale structural, chemical, and polarization behaviors in multiferroic\n  Sm-doped BiFeO3: The predictability of a certain effect or phenomenon is often equated with\nthe knowledge of relevant physical laws, typically understood as a functional\nor numerically derived relationship between the observations and known states\nof the system. Correspondingly, observations inconsistent with prior knowledge\ncan be used to derive new knowledge on the nature of the system or indicate the\npresence of yet unknown mechanisms. Here we explore the applicability of\nGaussian Processes (GP) to establish predictability and uncertainty of local\nbehaviors from multimodal observations, providing an alternative to this\nclassical paradigm. Using atomic-resolution Scanning Transmission Electron\nMicroscopy (STEM) of multiferroic Sm-doped BiFeO3 across a broad composition\nrange, we directly visualize the atomic structure and structural, physical, and\nchemical order parameter fields for the material. GP regression is used to\nestablish the predictability of the local polarization field from different\ngroups of parameters, including the adjacent polarization values and several\ncombinations of physical and chemical descriptors, including lattice\nparameters, column intensities, etc. We observe that certain elements of\nmicrostructure including charged and uncharged domain walls and interfaces with\nthe substrate are best predicted with specific combinations of descriptors, and\nthis predictability and their associated uncertainties are consistent across\nthe composition series. The associated generative physical mechanisms are\ndiscussed. We argue that predictability and uncertainty in observational data\noffers a new pathway to probe the physics of condensed matter systems from\nmultimodal local observations.",
        "positive": "Spintronic oxides grown by laser-MBE: The recent study of oxides led to the discovery of several new fascinating\nphysical phenomena. High-temperature superconductivity, colossal\nmagnetoresistance, dilute magnetic doping, or multiferroicity were discovered\nand investigated in transition-metal oxides, representing a prototype class of\nstrongly correlated electronic systems. This development was accompanied by an\nenormous progress regarding thin film fabrication. Within the past two decades,\nepitaxial thin films with crystalline quality approaching semiconductor\nstandards became available using laser molecular beam epitaxy. This evolution\nis reviewed, particularly with emphasis on transition-metal oxide thin films,\ntheir versatile physical properties, and their impact on the field of\nspintronics. First, the physics of ferromagnetic half-metallic oxides, such as\nthe doped manganites, the double perovskites and magnetite is presented\ntogether with possible applications based on magnetic tunnel junctions. Second,\nthe wide bandgap semiconductor zinc oxide is discussed particularly with regard\nto the controversy of dilute magnetic doping with transition-metal ions and the\npossibility of realizing p-type conductivity. Third, the field of oxide\nmultiferroics is presented with the recent developments in single-phase\nmultiferroic thin film perovskites as well as in composite multiferroic\nhybrids."
    },
    {
        "anchor": "Artificial Material with Negative Thermal Expansion: A Simple\n  Geometrical Approach: In the paper we report the modeling and design of material which has a\nnegative thermal expansion (NTE). The basic assumption is a potential between\nthe atoms in the material can be approximated by a Lennard-Jones potential\n(6-12) and the dominant interaction is only between nearest neighbors. We show\nthat the material formed by alternating atomic layers wherein each layer\ncontains a type of atom, and geometry of the arrangement of atoms is\ntriangular, may experience an NTE when sigma_AA = sigma_BB = sigma_AB,\nepsilon_AA = epsilon_BB < epsilon_AB/4 are satisfied, where sigma_ij and\nepsilon_ij are Lennard-Jones parameters",
        "positive": "Evolution of electronic and crystal structure during room-temperature\n  annealing of quenched REBa2Cu3O6+d, RE=Y, Nd: The crystal structure parameters and the low-temperature magnetic moment of\nthe HTSC cuprates YBa2Cu3O6+d, Y1-xCaxBa2Cu3O6+d, and Nd1+xBa2-xCu3O6+d, x =\n0.2 are recorded after quenching them from the temperature of oxidative\nannealing. The subject of the present study is the aging effect, which results\nin an increase in the critical temperature Tc and a decrease in the c parameter\nof the crystal lattice for a while after the quenching. On the example of\nYBa2Cu3O6+d, it is shown that the oxygen content dependence of c undergoes the\nfollowing changes with time: (1) there is an increase in the dependence slope\nwith respect to the (6+d)-axis; (2) there is an increase in the dependence\nnonlinearity. The first type of changes is explained by an increase in the\nvalence of copper ions in the CuOd planes that is accompanied by a decrease in\ntheir radius. The second type is explained by the electrostatic interaction of\nthe CuO2 structural planes due to the accumulation on them electron holes.\nCalculation of the parameter c changes shows good quantitative agreement with\nthe experimental data. The data obtained for the compounds Y1-xCaxBa2Cu3O6+d,\nand Nd1+xBa2-xCu3O6+d (the cases of the hole and electron doping of\nCuO2-planes) are discussed on the basis of the model representation developed\nby us for YBa2Cu3O6+d."
    },
    {
        "anchor": "Ultrahigh stiffness and anisotropic Dirac cones in BeN4 and MgN4\n  monolayers: A first-principles study: Beryllium polynitrides, BeN4 is a novel layered material, which has been most\nrecently fabricated under high pressure (Phys. Rev. Lett. 126(2021), 175501).\nAs a new class of 2D materials, in this work we conduct first-principles\ncalculations to examine the stability and explore the electronic nature of MN4\n(M= Be, Mg, Ir, Rh, Ni, Cu, Au, Pd, Pt) monolayers. Acquired results confirm\nthe dynamical and thermal stability of BeN4, MgN4, IrN4, PtN4 and RhN4\nmonolayers. Interestingly, BeN4 and MgN4 monolayers are found to show\nanisotropic Dirac cones in their electronic structure. While PtN4 monolayer is\npredicted to be a narrow band-gap semiconductor, IrN4 and RhN4 monolayers are\nfound to be metallic systems. We also elaborately explore the effects of number\nof atomic layers on the electronic features of BeN4 nanosheets, which reveal\nhighly appealing physics. Our results highlight that BeN4 nanosheet yield\nultrahigh elastic modulus and mechanical strength, outperforming all other\ncarbon-free 2D materials. Notably, RhN4 nanosheet is predicted to yield high\ncapacities of 562, 450 and 900 mAh/g, for Li, Na and Ca ions storages,\nrespectively. This study provides a comprehensive understanding on the\nintrinsic properties of MN4 nanosheets and highlight their outstanding physics.",
        "positive": "Phosphorene as a superior gas sensor: Selective adsorption and distinct\n  I-V response: Recent reports on the fabrication of phosphorene, i.e., mono- or few-layer\nblack phosphorus, have raised exciting prospects of an outstanding\ntwo-dimensional (2D) material that exhibits excellent properties for nanodevice\napplications. Here we study by first-principles calculations the adsorption of\nCO, CO2, NH3, NO and NO2 gas molecules on a mono-layer phosphorene. Our results\npredict superior sensing performance of phosphorene that rivals or even\nsurpasses other 2D materials such as graphene and MoS2. We determine the\noptimal adsorption positions of these molecules on the phosphorene and identify\nmolecular doping, i.e., charge transfer between the molecules and phosphorene,\nas the driving mechanism for the high adsorption strength. We further\ncalculated the current-voltage (I-V) relation using a non-equilibrium Greens\nfunction (NEGF) formalism. The transport features show large (one to two orders\nof magnitude) anisotropy along different (armchair or zigzag) directions, which\nis consistent with the anisotropic electronic band structure of phosphorene.\nRemarkably, the I-V relation exhibits distinct responses with a marked change\nof the I-V relation along either the armchair or the zigzag directions\ndepending on the type of molecules. Such selectivity and sensitivity to\nadsorption makes phosphorene a superior gas sensor that promises wide-ranging\napplications."
    },
    {
        "anchor": "Magnetic doping of a thiolated-gold superatom: The Au25(SR)18- cluster is a new member in the superatom family which\nfeatures a centered icosahedral shell (Au13) protected by six RS(AuSR)2 motifs\n(RS- being a alkylthiolate group). Here we show that this superatom can be\nmagnetically doped by replacing the center Au atom with Cr, Mn, or Fe. We find\nthat Cr and Mn-doped clusters have an optimized magnetic moment of 5 Bohr\nmagnetons while the Fe-doped cluster has an optimized magnetic moment of 3 Bohr\nmagnetons. Although the dopant atom's local magnetic moment makes a major\ncontribution to the total moment, the icosahedral Au12 shell is also found to\nbe significantly magnetized. Our work here provides a new scenario of magnetic\ndoping of a metal-cluster superatom which is protected by ligands and made by\nwet chemistry.",
        "positive": "Vertex corrections to the polarizability do not improve the GW\n  approximation for the ionization potential of molecules: The $GW$ approximation is based on the neglect of vertex corrections, which\nappear in the exact self-energy and the exact polarizability. Here, we\ninvestigate the importance of vertex corrections in the polarizability only. We\ncalculate the polarizability with equation-of-motion coupled-cluster theory\nwith single and double excitations (EOM-CCSD), which rigorously includes a\nlarge class of diagrammatically-defined vertex corrections beyond the random\nphase approximation (RPA). As is well-known, the frequency-dependent\npolarizability predicted by EOM-CCSD is quite different and generally more\naccurate than that predicted by the RPA. We evaluate the effect of these vertex\ncorrections on a test set of 20 atoms and molecules. When using a Hartree-Fock\nreference, ionization potentials predicted by the $GW$ approximation with the\nRPA polarizability are typically overestimated with a mean absolute error of\n0.3 eV. However, those predicted with a vertex-corrected polarizability are\ntypically underestimated with an increased mean absolute error of 0.5 eV. This\nresult suggests that vertex corrections in the self-energy cannot be neglected,\nat least for molecules. We also assess the behavior of eigenvalue\nself-consistency in vertex-corrected $GW$ calculations, finding a further\nworsening of the predicted ionization potentials."
    },
    {
        "anchor": "Absence of Critical Thickness in an Ultrathin Improper Ferroelectric\n  Film: We study the ferroelectric stability and surface structural properties of an\noxygen-terminated hexagonal YMnO$_3$ ultra-thin film using density functional\ntheory. Under an open circuit boundary condition, the ferroelectric state with\nthe spontaneous polarization normal to the (0001) surface, is found to be\nmetastable in a single domain state despite the presence of a depolarizing\nfield. We establish a connection between the result and the role of improper\nferroelectric transition. Our results imply that improper ferroelectric\nultrathin films can have rather unique properties that are distinctive from\nthose of very thin films of ordinary ferroelectrics.",
        "positive": "Materials considerations for forming the topological insulator phase in\n  InAs/GaSb heterostructures: In an ideal InAs/GaSb bilayer of appropriate dimension in-plane electron and\nhole bands overlap and hybridize, and a topologically non-trivial, or quantum\nspin Hall (QSH) insulator, phase is predicted to exist. The in-plane\ndispersion's potential landscape, however, is subject to microscopic\nperturbations originating from material imperfections. In this work, the effect\nof disorder on the electronic structure of InAs/GaSb bilayers was studied by\nthe temperature and magnetic field dependence of the resistance of a dual-gated\nheterostructures gate-tuned through the inverted to normal gap regimes.\nConduction in the inverted (predicted topological) regime was qualitatively\nsimilar to behavior in a disordered two-dimensional system. The impact of\ncharged impurities and interface roughness on the formation of topologically\nprotected edge states and an insulating bulk was estimated. The experimental\nevidence and estimates of disorder in the potential landscape indicated the\npotential fluctuations in state-of-the-art films are sufficiently strong such\nthat conduction in the predicted topological insulator (TI) regime was\ndominated by a symplectic metal phase rather than a TI phase. The implications\nare that future efforts must address disorder in this system and focus must be\nplaced on the reduction of defects and disorder in these heterostructures if a\nTI regime is to be achieved."
    },
    {
        "anchor": "Thin film growth of MAX phases as functional materials: Layered nanolaminate ternary carbides, nitrides and carbonitrides with\ngeneral formula Mn+1AXn or MAX (n = 1, 2, or 3, M is an early transition metal,\nA is mostly group 13 or 14 element, and X is C and/or N) has revolutionized the\nworld of nanomaterials, due to the coexistence of both ceramic and metallic\nnature, giving rise to exceptional mechanical, thermal, electrical, chemical\nproperties and wide range of applications. Although several solid-state bulk\nsynthesis methods have been developed to produce a variety of MAX phases,\nhowever, for certain applications, the growth of MAX phases, especially in its\nhigh-quality epitaxial thin films form is of increasing interest. Here, we\nsummarize the progress made thus far in epitaxial growth and property\nevaluation of MAX phase thin films grown by various deposition techniques. We\nalso address the important future research directions to be made in terms of\nthin-film growth. Overall, in the future, high-quality single-phase epitaxial\nthin film growth and engineering of chemically diverse MAX phases may open up\ninteresting new avenues for next-generation technology.",
        "positive": "The Structural Phase Transition of the Relaxor Ferroelectric\n  68%PbMg1/3Nb2/3O3-32%PbTiO3: Neutron scattering techniques have been used to study the relaxor\nferroelectric 0.68PbMg1/3Nb2/3O3-0.32PbTiO3 denoted in this paper as\n0.68PMN-0.32PT. On cooling, these relaxor ferroelectrics have a long-range\nordered ferroelectric phase and the composition is close to that at which the\nferroelectric structure changes from rhombohedral to tetragonal. It was found\nthat above the Burns temperature of about 600K, the transverse optic mode and\nthe transverse acoustic mode are strongly coupled and a model was used to\ndescribe this coupling that gave similar parameters to those obtained for the\ncoupling in PMN. Below the Burns temperature additional quasi-elastic\nscattering was found which increased in intensity as the sample was cooled down\nto the ferroelectric transition temperature but then decreased in intensity.\nThis behaviour is similar to that found in PMN. This scattering is associated\nwith the dynamic polar nano-regions that occur below the Burns temperature. In\naddition to this scattering a strictly elastic resolution limited peak was\nobserved that was much weaker than the corresponding peak in pure PMN and which\ndecreased in intensity on cooling below the ferroelectric phase whereas for\nPMN, which does not have a long-range ordered ferroelectric phase, the\nintensity of this component increased monotonically as the sample was cooled.\nThe results of our study are compared with the recent measurements of Stock et\nal. [PRB 73 064107] who studied 0.4PMN-0.6PT. The results are qualitatively\nconsistent with the random field model developed to describe the scattering\nfrom PMN."
    },
    {
        "anchor": "On the group-theoretical approach to the study of interpenetrating nets: A general theoretical framework based on group-subgroup and group-supergroup\nrelations is proposed to describe and to derive interpenetrating nets.",
        "positive": "Novel 122-type Ir-based superconductors BaIr2Mi2 (Mi = P and As): A\n  density functional study: We explore the structural, electronic, bonding, mechanical, thermodynamic and\nsuperconducting properties of two newly discovered isostructural bulk\nsuperconductors barium iridium phosphide BaIr2P2 (Tc ~ 2.1 K) and barium\niridium arsenide BaIr2As2 (Tc ~ 2.45 K). The optimized structural parameters of\nboth the compounds show good agreement with the experimentally evaluated\nvalues. The replacement of P by As mostly affects the c value, whereas a\nremains approximately the same. Metallic conductivity is observed for both the\nsuperconductors. The analysis of DOS, Mulliken atomic populations and total\ncharge density revel a complex bonding in BaIr2P2 and BaIr2As2 with ionic,\ncovalent and metallic characteristics. Mechanical and dynamical stability of\nboth the phases is confirmed by analyzing the elastic constant data."
    },
    {
        "anchor": "An Analysis of the Quasicontinuum Method: The aim of this paper is to present a streamlined and fully three-dimensional\nversion of the quasicontinuum (QC) theory of Tadmor et al. and to analyze its\naccuracy and convergence characteristics. Specifically, we assess the effect of\nthe summation rules on accuracy; we determine the rate of convergence of the\nmethod in the presence of strong singularities, such as point loads; and we\nassess the effect of the refinement tolerance, which controls the rate at which\nnew nodes are inserted in the model, on the development of dislocation\nmicrostructures.",
        "positive": "Coherent magnetization dynamics in strongly quenched Ni thin films: The remagnetization process after ultrafast demagnetization can be described\nby relaxation mechanisms between the spin, electron, and lattice reservoirs.\nThereby, collective spin excitations in form of spin waves and their angular\nmomentum transfer play an important role on the longer timescales. In this\nwork, we address the question whether the strength of demagnetization affects\nthe coherency and the phase of the excited spin waves. We present a study of\ncoherent magnetization dynamics in thin nickel films after ultrafast\ndemagnetization using the all-optical, time-resolved magneto-optical\nKerr-effect (tr-MOKE) technique. The largest coherent oscillation amplitude was\nobserved for strongly quenched systems, showing the conservation of coherency\nfor demagnetizations of up to 90%. Moreover, the phase of the excited\nspin-waves increases with pump power, indicating a delayed start of the\nprecession during the remagnetization."
    },
    {
        "anchor": "On complex permittivity of dilute random binary dielectric mixtures in\n  two-dimensions: Influence of number of particles considered in numerical simulations on\ncomplex dielectric permittivity of binary dilute dielectric mixtures in\ntwo-dimensions are reported. In the simulations, dodecagons (polygons with\n12-sides) were used to mimic disk-shaped inclusions. Using such an approach we\nwere able to consider $16^2$ particles in a unit-square. The effective\ndielectric permittivity of the mixtures were calculated using the finite\nelement at two different frequecies which were much higher and lower than the\ncharacteristic relaxation rate of the Maxwell-Wagner-Sillars polarization. The\nresults were compared to an analytical solution. It was found that the\npermittivity values at low frequencies were inside Wiener bounds however they\nviolated the Hashin-Shtrikman bounds.",
        "positive": "DFT study of undoped and As-doped Si nanowires approaching the bulk\n  limit: The electronic properties of pure and As-doped Si nanowires with radii up to\n9.53 nm are studied using large scale density functional theory (DFT)\ncalculations. We show that, for the undoped nanowires, the DFT bandgap reduces\nwith increasing diameter and converges to its bulk value, a trend in agreement\nwith experimental data. Moreover, we show that the atoms closest to the surface\nof the nanowire contribute less to the states near the band edges, when\ncompared with atoms close to the centre; this is shown to be due to differences\nin Si-Si atomic distances, as well as surface passivation effects. When\nconsidering As-doped Si nanowires we show that dopant placement within the\nnanowire plays an important role in deciding electronic properties. We show\nthat a low velocity band is introduced by As doping, in the gap, but close to\nthe conduction band edge. The dopant location affects the curvature of this\nband, with the curvature reducing when the dopant is placed closer to the\ncenter. We also show that asymmetry of dopant location with the nanowire leads\nto splitting of the valence band edge."
    },
    {
        "anchor": "VASP on a GPU: application to exact-exchange calculations of the\n  stability of elemental boron: General purpose graphical processing units (GPU's) offer high processing\nspeeds for certain classes of highly parallelizable computations, such as\nmatrix operations and Fourier transforms, that lie at the heart of\nfirst-principles electronic structure calculations. Inclusion of exact-exchange\nincreases the cost of density functional theory by orders of magnitude,\nmotivating the use of GPU's. Porting the widely used electronic density\nfunctional code VASP to run on a GPU results in a 5-20 fold performance boost\nof exact-exchange compared with a traditional CPU. We analyze performance\nbottlenecks and discuss classes of problems that will benefit from the GPU. As\nan illustration of the capabilities of this implementation, we calculate the\nlattice stability {\\alpha}- and {\\beta}-rhombohedral boron structures utilizing\nexact-exchange. Our results confirm the energetic preference for\nsymmetry-breaking partial occupation of the {\\beta}-rhombohedral structure at\nlow temperatures, but does not resolve the stability of {\\alpha} relative to\n{\\beta}.",
        "positive": "Thermal and Pressure Ionization in Warm, Dense MgSiO$_3$ Studied with\n  First-Principles Computer Simulations: Using path integral Monte Carlo and density functional molecular dynamics\n(DFT-MD) simulations, we study the properties of MgSiO$_3$ enstatite in the\nregime of warm dense matter. We generate a consistent equation of state (EOS)\nthat spans across a wide range of temperatures and densities (10$^4$--10$^7$ K\nand 6.42--64.16 g cm$^{-3}$). We derive the shock Hugoniot curve, that is in\ngood agreement with the experiments. We identify the boundary between the\nregimes of thermal ionization and pressure ionization by locating where the\ninternal energy at constant temperature attains a minimum as a function of\ndensity or pressure. At low density, the internal energy decreases with\nincreasing density as the weight of free states changes. Thermal ionization\ndominates. Conversely, at high density, in the regime of pressure ionization,\nthe internal energy increases with density. We determine the boundary between\nthe two regimes and show that the compression maximum along the shock Hugoniot\ncurve occurs because K shell electrons become thermally ionized rather than\npressure ionized."
    },
    {
        "anchor": "Lattice screening of the polar catastrophe and hidden in-plane\n  polarization in KNbO$_{3}$/BaTiO$_{3}$ interfaces: We have carried out first-principles simulations, based on density functional\ntheory, to obtain the atomic and electronic structure of (001)\nBaTiO$_{3}$/KNbO$_{3}$ interfaces in an isolated slab geometry. We tried\ndifferent types of structures including symmetric and asymmetric\nconfigurations, and variations in the thickness of the constituent materials.\nThe spontaneous polarization of the layer-by-layer non neutral material\n(KNbO$_{3}$) in these interfaces cancels out almost exactly the \"built-in\"\npolarization responsible for the electronic reconstruction. As a consequence,\nthe so-called polar catastrophe is quenched and all the simulated interfaces\nare insulating. A model, based on the modern theory of polarization and basic\nelectrostatics, allows an estimation of the critical thickness for the\nformation of the two-dimensional electron gas between 42 and 44 KNbO$_{3}$ unit\ncells. We also demonstrate the presence of an unexpected in-plane polarization\nin BaTiO$_{3}$ localized at the $p$-type TiO$_2$/KO interface, even under\nin-plane compressive strains. We expect this in-plane polarization to remain\nhidden due to angular averaging during quantum fluctuations unless the symmetry\nis broken with small electric fields.",
        "positive": "Obstructed atomic insulators: A rational strategy to reach\n  two-dimensional quasi-particles: Here, using the topological quantum chemistry theory, we present a strategy\nto reach two-dimensional (2D) quasi-particles, which is benefiting from\nfeatured floating surface states (FSSs) of a three-dimensional (3D) obstructed\natomic insulator (OAI). Symmetry of obstructed Wannier charge centers\nguarantees that such FSSs degenerate at high symmetry points or invariant lines\nin the surface Brillouin zone. Based on symmetry analysis and first-principles\ncalculations, we identify that a carbon allotrope with a 20-atom body-centered\ntetragonal (bct) unit cell (\\textit{i.e.}, termed bct-C$_{20}$), where the OAI\nphase is verified, is an ideal candidate to achieve our strategy. There are\nfour in-gap FSSs, which simultaneously form two kinds of surface Dirac cones,\n\\textit{i.e.}, topological Dirac cones with linear dispersion and\nsymmetry-enforced quadratic Dirac cones. The band topology of surface Dirac\ncone is depicted by the effective surface Hamiltonian and the emergence of a\nhinge state. Our work would absolutely inspire interest in research concerning\nrevealing more 2D topological states and related practical applications."
    },
    {
        "anchor": "Macroscopic constitutive law for Mastic Asphalt Mixtures from multiscale\n  modeling: A well established framework of an uncoupled hierarchical modeling approach\nis adopted here for the prediction of macroscopic material parameters of the\nGeneralized Leonov (GL) constitutive model intended for the analysis of\nflexible pavements at both moderate and elevated temperature regimes. To that\nend, a recently introduced concept of a statistically equivalent periodic unit\ncell (SEPUC) is addressed to reflect a real microstructure of Mastic Asphalt\nmixtures (MAm). While mastic properties are derived from an extensive\nexperimental program, the macroscopic properties of MAm are fitted to virtual\nnumerical experiments performed on the basis of first order homogenization\nscheme. To enhance feasibility of the solution of the underlying nonlinear\nproblem a two-step homogenization procedure is proposed. Here, the effective\nmaterial properties are first found for a mortar phase, a composite consisting\nof a mastic matrix and a fraction of small aggregates. These properties are\nthen introduced in place of the matrix in actual unit cells to give estimates\nof the model parameters on macroscale. Comparison with the Mori-Tanaka\npredictions is also provided suggesting limitations of classical\nmicromechanical models.",
        "positive": "Revolutionary valorization of carbon dioxide into dimethyl carbonate is\n  catalyzed by sodium chloride: cheap, clean, one-pot, and water-free synthesis: The robust valorization of carbon dioxide (CO2) stays at the center of\nsustainable development. Since CO2 represents a low-energy compound, its\ntransformation into commercially coveted products is cumbersome. In the present\nwork, we report a revolutionary method to obtain dimethyl carbonate (DMC) out\nof methanol (CH3OH) and CO2 catalyzed by sodium chloride (NaCl) and similar\ninorganic salts. The computational exploration revealed a mechanism of\nfavorable catalysis, which was subsequently confirmed experimentally. Unlike\nall competitive syntheses of DMC, the new one does not produce water and,\ntherefore, the hydrolysis of a carbonate does not occur. No dehydrating agents\nare necessary. The employed catalyst is cheap and permanently exists in the\nsame phase with the reactants and products. The action of NaCl was compared to\nthose of other alkali metal salts, LiI, LiCl, and KI, and competitive\nperformances were recorded. The experimentally obtained result outperforms most\ncompeting technologies according to the DMC yield, 19% with molecular sieves\nand 17% without molecular sieves. All existing competitors are excelled by the\nsimplicity and cleanness of the synthesis. The reported advance substantially\nsimplifies the synthesis of linear organic carbonates and robustly valorizes\nCO2. Keywords: Dimethyl carbonate; carbon dioxide utilization; sodium chloride;\nmethanol."
    },
    {
        "anchor": "The electronic structure of clean and adsorbate-covered Bi2Se3: an\n  angle-resolved photoemission study: Angle-resolved photoelectron spectroscopy is used for a detailed study of the\nelectronic structure of the topological insulator Bi2Se3. Nominally\nstoichiometric and calcium-doped samples were investigated. The pristine\nsurface shows the topological surface state in the bulk band gap. As time\npasses, the Dirac point moves to higher binding energies, indicating an\nincreasingly strong downward bending of the bands near the surface. This\ntime-dependent band bending is related to a contamination of the surface and\ncan be accelerated by intentionally exposing the surface to carbon monoxide and\nother species. For a sufficiently strong band bending, additional states appear\nat the Fermi level. These are interpreted as quantised conduction band states.\nFor large band bendings, these states are found to undergo a strong Rashba\nsplitting. The formation of quantum well states is also observed for the\nvalence band states. Different interpretations of similar data are also\ndiscussed.",
        "positive": "Growth Structure and Work Function of Bilayer Graphene on Pd(111): Using in situ low-energy electron microscopy and density functional theory,\nwe studied the growth structure and work function of bilayer graphene on\nPd(111). Low-energy electron diffraction analysis established that the two\ngraphene layers have multiple rotational orientations relative to each other\nand the substrate plane. We observed heterogeneous nucleation and simultaneous\ngrowth of multiple, faceted layers prior to the completion of second layer. We\npropose that the facetted shapes are due to the zigzag-terminated edges\nbounding graphene layers growing under the larger overlying layers. We also\nfound that the work functions of bilayer graphene domains are higher than those\nof monolayer graphene, and depend sensitively on the orientations of both\nlayers with respect to the substrate. Based on first-principles simulations, we\nattribute this behavior to oppositely oriented electrostatic dipoles at the\ngraphene/Pd and graphene/graphene interfaces, whose strengths depend on the\norientations of the two graphene layers."
    },
    {
        "anchor": "A novel approach to quantify the structural distortions of U/Th\n  snub-disphenoids and their role in zircon to reidite type phase transitions\n  of uranothorite: Our density functional study reveals a peculiar relation between the\nnormalized Th content i.e. Th/(U+Th) and the hydrostatic pressure enforcing\nzircon to reidite type transition in uranothorite solid solution. We found that\nthe transition pressure exhibits a minimum when Th/(U+Th) = 0.50 i.e. when the\nunit cell contains equal amount of U and Th. Any change in normalized Th\ncontent, as we move towards the U and Th end-members of the series, shows a\nsignificant jump in zircon-reidite transition pressure. In order to explain\nthis behavior, we proposed a novel method of quantifying the distortions of\nU/Th-coordination polyhedra which manifest themselves as a triangular\ndodecahedron or snub-disphenoid. We have theoretically defined two parameters:\none related to the two geometrically different U/Th-O bond lengths, having a\nfixed ratio between them for regular triangular dodecahedra irrespective of the\nvolume and the other with three kinds of O-U-O and O-Th-O bond angles with\nmultiplicities of 2, 4 and 12, respectively. The bond angle distortion for both\nU and Th-polyhedra were found to show a maximum in zircon phase and a minimum\nin reidite phase corresponding to Th/(U+Th) = 0.5. Since, the difference in\nangular distortion is minimum in case of Th/(U+Th) = 0.5, a lesser hydrostatic\npressure is capable of triggering the transition, compared to the other members\nof this series. The bond length distortion is also characterized by a maximum\nin the reidite phase at the equal concentration of U and Th. Our finding is\nalso complemented by the minimum compressibility observed in the zircon phase\nwhen the atomic percentage of U and Th are equal.",
        "positive": "First-principles study of UO$_2$ lattice thermal-conductivity: A simple\n  description: Modeling the high-$T$ paramagnetic state of bulk UO$_2$ by a\nnon-spin-polarized calculation and neglecting the Hubbard-U correction for the\n$f$ electrons in U atoms, the lattice thermal conductivity of bulk UO$_2$ is\ninvestigated by the exact solution of the Boltzmann transport equation for the\nsteady-state phonon distribution function. The results show that TA branches\ncorresponding to U-atoms vibrations have the largest lifetimes and therefore\nhave dominant role in thermal conductivity, while the optical branches\ncorresponding mainly to O-atoms vibrations have the shortest lifetimes. Using\nthis simple model, our results for the thermal conductivity show a very good\nagreement with the experiments. The calculations are repeated for bulk UO$_2$\nwith different U-235 concentrations of 3\\%, 5\\%, 7\\%, and 20\\%, and the results\nshow a small decrease of thermal conductivity which arise from scattering of\nphonons by impurities."
    },
    {
        "anchor": "Misfit Strain Accommodation in Epitaxial ABO3 Perovskites: Lattice\n  Rotations and Lattice Modulations: We present a study of the lattice response to the compressive and tensile\nbiaxial stress in La0.67Sr0.33MnO3 (LSMO) and SrRuO3 (SRO) thin films grown on\na variety of single crystal substrates: SrTiO3, DyScO3, NdGaO3 and\n(La,Sr)(Al,Ta)O3. The results show, that in thin films under misfit strain,\nboth SRO and LSMO lattices, which in bulk form have orthorhombic (SRO) and\nrhombohedral (LSMO) structures, assume unit cells that are monoclinic under\ncompressive stress and tetragonal under tensile stress. The applied stress\neffectively modifies the BO6 octahedra rotations, which degree and direction\ncan be controlled by magnitude and sign of the misfit strain. Such lattice\ndistortions change the B-O-B bond angles and therefore are expected to affect\nmagnetic and electronic properties of the ABO3 perovskites.",
        "positive": "On some extreme cohesive properties of alpha-Plutonium: temperature\n  dependence of elastic moduli, large pressure derivative of bulk modulus and\n  Gr\u016bneisen parameter: The basic observed cohesive properties of alpha-Pu like temperature variation\nof elastic moduli, large value of the pressure derivative of the bulk modulus\nand anomalous values of the Gruneisen parameter in literature are not yet\ncompletely understood. In this communication, we provide new insights into\nthese."
    },
    {
        "anchor": "Heterogeneous nucleation and adatom detachment at 1-D growth of Indium\n  on Si(100)-2x1: Growth of atomic indium chains - 1D islands - on the Si(100)-2x1 surface was\nobserved by scanning tunneling microscopy (STM) at room temperature and\nsimulated by means of a kinetic Monte Carlo method. Density of indium islands\nand island size distribution were obtained for various deposition rates and\ncoverage. STM observation of growth during deposition of indium provided\ninformation on growth kinetics and relaxation of grown layers. Important role\nof C-type defects at adsorption of metal atoms was observed. Measured growth\ncharacteristics were simulated using a microscopic model with anisotropic\nsurface diffusion and forbidden zones along the metal chains. An analysis of\nexperimental and simulation data shows that detachment of indium adatoms from\nthe chains substantially influences a growth scenario and results in\nmonotonously decreasing chain length distribution function at low coverage.\nDiffusion barriers determined from the simulations correspond to almost\nisotropic diffusion of indium adatoms on the surface. The results are discussed\nwith respect to data reported in earlier papers for other metals.",
        "positive": "Silicene Structures on Silver Surfaces: In this paper we report on several structures of silicene, the analog of\ngraphene for silicon, on the silver surfaces Ag(100), Ag(110) and Ag(111).\nDeposition of Si produces honeycomb structures on these surfaces. In\nparticular, we present an extensive theoretical study of silicene on Ag(111)\nfor which several recent experimental studies have been published. Different\nsilicene structures were obtained only by varying the silicon coverage and/or\nits atomic arrangement. All the structures studied show that silicene is\nbuckled, with a Si-Si nearest neighbor distance varying between 2.28 and 2.5\nA{\\deg} . Due to the buckling in the silicene sheet, the apparent (lateral)\nSi-Si distance can be as low as 1.89 A{\\deg} . We also found that for a given\ncoverage and symmetry, one may observe different scanning tunneling microscopy\nimages corresponding to structures that differ by only a translation."
    },
    {
        "anchor": "Image processing-based domain-matching simulation for heteroepitaxy: Heteroepitaxy of functional thin films on single-crystal substrates is one of\nthe most general themes in electronic materials research. Here, we propose an\nalgorithm based on image processing for the rapid simulation of heteroepitaxial\nrelationships. The superposition and rotation of various lattice plane images\nof the film and substrate, which were automatically generated from the crystal\nstructure, rapidly verified all domain matching patterns. Furthermore, the\ncomprehensive validation allowed us to discuss domain matching from multiple\nperspectives, such as mismatch, matching period, and density of matching\nlattice points. Therefore, the proposed algorithm will contribute to materials\ninformatics, streamlining a wide range of materials research for functional\nthin films.",
        "positive": "Temperature dependent striction effect in a single crystalline Nd2Fe14B\n  revealed using a novel high temperature resistivity measurement technique: We studied the temperature dependence of resistivity in a single crystalline\nNd2Fe14B using a newly developed high temperature probe. This novel probe uses\nmechanical pin connectors instead of conducting glue/paste. From warming and\ncooling curves, the Curie temperature was consistently measured around Tc = 580\nK. In addition, anomalous discrete jumps were found only in cooling curves\nbetween 400 and 500 K, but not shown in warming curves. More interestingly,\nwhen the jumps occurred during cooling, the resistivity was increased. This\nphenomenon can be understood in terms of temperature dependent striction effect\ninduced by the re-orientation of magnetic domains well below the Curie\ntemperature."
    },
    {
        "anchor": "High frequency Scanning Gate Microscopy and local memory effect of\n  carbon nanotube transistors: We use impedance spectroscopy to measure the high frequency properties of\nsingle-walled carbon nanotube field effect transistors (swCN-FETs).\nFurthermore, we extend Scanning Gate Microscopy (SGM) to frequencies up to\n15MHz, and use it to image changes in the impedance of swCN-FET circuits\ninduced by the SGM-tip gate. In contrast to earlier reports, the results of\nboth experiments are consistent with a simple RC parallel circuit model of the\nswCN-FET, with a time constant of 0.3 ms. We also use the SGM tip to show the\nlocal nature of the memory effect normally observed in swCN-FETs, implying that\nnanotube-based memory cells can be miniaturized to dimensions of the order of\ntens of nm.",
        "positive": "Diverse fundamental properties in stage-n graphite alkali-intercalation\n  compounds: anode materials of Li+-based batteries: The diversified essential properties of the stage-n graphite\nalkali-intercalation compounds are thoroughly explored by the first-principles\ncalculations. According to their main features, the lithium and non-lithium\nmaterials might be quite different from each other in stacking configurations,\nthe intercalated alkali-atom concentrations, the free conduction electron\ndensities, and the atom-dominated & (carbon, alkali)-co-dominated energy bands.\nThe close relations between the alkali-doped metallic behaviors and the\ngeometric symmetries will be clarified through the interlayer atomic\ninteractions, in which the significant alkali-carbon chemical bondings are\nfully examined from the atom- and orbital-decomposed van Hove singularities.\nThe blue shift of the Fermi level, the n-type doping, is clearly identified\nfrom the low-energy features of the density of states. This study is able to\nprovide the partial information about anode of Li+-based battery. There are\ncertain important differences between AC$_6$/AC$_8$ and Li$_8$Si$_4$O$_{12}$."
    },
    {
        "anchor": "A unified model for temperature dependent electrical conduction in\n  polymer electrolytes: The observed temperature dependence of electrical conduction in polymer\nelectrolytes is usually fitted with two separated equations: an Arrhenius\nequation at low temperatures and Vogel-Tamman-Fulcher (VTF) at high\ntemperatures. We report here a derivation of a single equation to explain the\nvariation of electrical conduction in polymer electrolytes at all temperature\nranges. Our single equation is in agreement with the experimental data",
        "positive": "99.992 % $^{28}$Si CVD-grown epilayer on 300 mm substrates for large\n  scale integration of silicon spin qubits: Silicon-based quantum bits with electron spins in quantum dots or nuclear\nspins on dopants are serious contenders in the race for quantum computation.\nAdded to process integration maturity, the lack of nuclear spins in the most\nabundant $^{28}$silicon isotope host crystal for qubits is a major asset for\nthis silicon quantum technology. We have grown $^{28}$silicon epitaxial layers\n(epilayers) with an isotopic purity greater than 99.992 % on 300mm natural\nabundance silicon crystals. The quality of the mono-crystalline isotopically\npurified epilayer conforms to the same drastic quality requirements as the\nnatural epilayers used in our pre-industrial CMOS facility. The isotopically\npurified substrates are now ready for the fabrication of silicon qubits using a\nstate-of-the-art 300 mm Si CMOS-foundries equipment and processes"
    },
    {
        "anchor": "Elliptically polarized terahertz radiation from a chiral oxide: Polarization control of terahertz wave is a challenging subject in terahertz\nscience and technology. Here, we report a simple method to control polarization\nstate of the terahertz wave in terahertz generation process. At room\ntemperature, terahertz radiation from a noncentrosymmetric and chiral oxide,\nsillenite Bi$_{12}$GeO$_{20}$, is observed by the irradiation of linearly\npolarized femtosecond laser pulses at 800 nm. The polarization state of the\nemitted terahertz wave is found to be elliptic with an ellipticity of\n$\\sim$0.37$\\pm$0.10. Furthermore, the ellipticity was altered to a nearly zero\n($\\sim$0.01$\\pm$0.01) by changing the polarization of the incident linearly\npolarized femtosecond laser pulses. Such a terahertz radiation characteristic\nis attributable to variation of the polarization state of the emitted terahertz\nwaves, which is induced by retardation due to the velocity mismatch between the\nincident femtosecond laser pulse and generated terahertz wave and by the\npolarization tilting due to the optical activity at 800 nm.",
        "positive": "The effect of exclusion on nonlinear reaction diffusion system in\n  inhomogeneous media: We study a minimal model to understand the formation of clusters on surfaces\nin the presence of surface defects. We consider reaction diffusion model in\nwhich atoms undergoes reactions at the defect centers to form clusters. Volume\nexclusion between particles is introduced through a drift term in the reaction\ndiffusion equation that arises due the repulsive force field produced by the\nclustering atoms. The volume exclusion terms can be derived from master\nequation with a concentration dependent hopping rate. Perturbative analysis is\nperformed for both cross-exclusion and self-exclusion one dimensional system.\nFor two dimension numerical analysis is performed. We have found that the\nclusterization process slows down due to exclusion. As a result the size of the\nclusters reduces. In this model reaction scheme has algebraic nonlinearity and\nplausible mechanism is also given."
    },
    {
        "anchor": "Determination of the origin of the spin Seebeck effect - bulk vs.\n  interface effects: The observation of the spin Seebeck effect in insulators has meant a\nbreakthrough for spin caloritronics due to the unique ability to generate pure\nspin currents by thermal excitations in insulating systems without moving\ncharge carriers. Since the recent first observation, the underlying mechanism\nand the origin of the observed signals have been discussed highly\ncontroversially. Here we present a characteristic dependence of the\nlongitudinal spin Seebeck effect amplitude on the thickness of the insulating\nferromagnet (YIG). Our measurements show that the observed behavior cannot be\nexplained by any effects originating from the interface, such as magnetic\nproximity effects in the spin detector (Pt). Comparison to theoretical\ncalculations of thermal magnonic spin currents yields qualitative agreement for\nthe thickness dependence resulting from the finite effective magnon propagation\nlength so that the origin of the effect can be traced to genuine bulk magnonic\nspin currents ruling out parasitic interface effects.",
        "positive": "Kinetic electrocaloric effect and giant net cooling of lead-free\n  ferroelectric refrigerants: Giant electrocaloric (EC) effect is observed in BaTiO3 multilayer thick film\nstructure. The temperature change is as high as 4.0 oC under an applied\nelectric field of 352 kV/cm. Most importantly, the EC effect is found to depend\non the varying rate of the applied field. Based on the giant net cooling (~0.37\nJ/g) resulting from the difference in the varying rates of rising and falling\nfields, the kinetic EC effect provides an effective solution for the design of\nrefrigeration cycle in ferroelectric micro-refrigerator."
    },
    {
        "anchor": "RESCU: a Real Space Electronic Structure Method: In this work we present RESCU, a powerful MATLAB-based Kohn-Sham density\nfunctional theory (KS-DFT) solver. We demonstrate that RESCU can compute the\nelectronic structure properties of systems comprising many thousands of atoms\nusing modest computer resources, e.g. 16 to 256 cores. Its computational\nefficiency is achieved from exploiting four routes. First, we use numerical\natomic orbital (NAO) techniques to efficiently generate a good quality initial\nsubspace which is crucially required by Chebyshev filtering methods. Second, we\nexploit the fact that only a subspace spanning the occupied Kohn-Sham states is\nrequired, and solving accurately the KS equation using eigensolvers can\ngenerally be avoided. Third, by judiciously analyzing and optimizing various\nparts of the procedure in RESCU, we delay the $O(N^3)$ scaling to large $N$,\nand our tests show that RESCU scales consistently as $O(N^{2.3})$ from a few\nhundred atoms to more than 5,000 atoms when using a real space grid\ndiscretization. The scaling is better or comparable in a NAO basis up to the\n14,000 atoms level. Fourth, we exploit various numerical algorithms and, in\nparticular, we introduce a partial Rayleigh-Ritz algorithm to achieve\nefficiency gains for systems comprising more than 10,000 electrons. We\ndemonstrate the power of RESCU in solving KS-DFT problems using many examples\nrunning on 16, 64 and/or 256 cores: a 5,832 Si atoms supercell; a 8,788 Al\natoms supercell; a 5,324 Cu atoms supercell and a small DNA molecule submerged\nin 1,713 water molecules for a total 5,399 atoms. The KS-DFT is entirely\nconverged in a few hours in all cases. Our results suggest that the RESCU\nmethod has reached a milestone of solving thousands of atoms by KS-DFT on a\nmodest computer cluster.",
        "positive": "First-principles study on field evaporation of surface atoms from W(011)\n  and Mo(011) surfaces: The simulations of field-evaporation processes for surface atoms on W(011)\nand Mo(011) surfaces are implemented using first-principles calculations based\non the real-space finite-difference method. The threshold values of the\nexternal electric field for evaporation of the surface atoms, which are $\\sim$\n6 V/\\AA 2mm for tungsten and $\\sim$ 5 V/\\AA 2mm for molybdenum, are in\nagreement with the experimental results. Whereas field evaporation has been\nbelieved to occur as a result of significant local-field enhancement around the\nevaporating atoms, in this study, the enhancement is not observed around the\natoms but above them and the strength of the local field is much smaller than\nthat expected on the basis of the classical model."
    },
    {
        "anchor": "Experimental and Theoretical Investigation on the Possible Half-metallic\n  Behaviour of Equiatomic Quaternary Heusler Alloys: CoRuMnGe and CoRuVZ (Z =\n  Al, Ga): In this report, structural, electronic, magnetic and transport properties of\nquaternary Heusler alloys CoRuMnGe and CoRuVZ (Z = Al, Ga) are investigated.\nAll the three alloys are found to crystallize in cubic structure. CoRuMnGe\nexhibits L2$_1$ structure whereas, the other two alloys have B2-type disorder.\nFor CoRuMnGe and CoRuVGa, the experimental magnetic moments are in close\nagreement with the theory as well as those predicted by the Slater-Pauling\nrule, while for CoRuVAl, a relatively large deviation is seen. The reduction in\nthe moment in case of CoRuVAl possibly arises due to the anti-site disorder\nbetween Co and Ru sites as well as V and Al sites. Among these alloys, CoRuMnGe\nhas the highest T$\\mathrm{_C}$ of 560 K. Resistivity variation with temperature\nreflects the half-metallic nature in CoRuMnGe alloy. CoRuVAl shows metallic\ncharacter in both paramagnetic and ferromagnetic states, whereas the\ntemperature dependence of resistivity for CoRuVGa is quite unusual. In the last\nsystem, $\\rho$ vs. T curve shows an anomaly in the form of a maximum and a\nregion of negative temperature coefficient of resistivity (TCR) in the\nmagnetically ordered state. The ab initio calculations predict nearly\nhalf-metallic ferromagnetic state with high spin polarization of 91, 89 and 93\n\\% for CoRuMnGe, CoRuVAl and CoRuVGa respectively. To investigate the\nelectronic properties of the experimentally observed structure, the Co-Ru swap\ndisordered structures of CoRuMnGe alloy are also simulated and it is found that\nthe disordered structures retain half-metallic nature, high spin polarization\nwith almost same magnetic moment as in the ideal structure. Nearly\nhalf-metallic character, high T$\\mathrm{_C}$ and high spin polarization make\nCoRuMnGe alloy promising for room temperature spintronic applications.",
        "positive": "Neutron diffraction and magnetic properties of Co$_2$Cr$_{1-x}$Ti$_x$Al\n  Heusler alloys: We report the structural, magnetic, and magnetocaloric properties of\nCo$_2$Cr$_{1-x}$Ti$_x$Al ($x=$ 0--0.5) Heusler alloys for spintronic and\nmagnetic refrigerator applications. Room temperature X-ray diffraction and\nneutron diffraction patterns along with Rietveld refinements confirm that the\nsamples are of single phase and possess a cubic structure. Interestingly,\nmagnetic susceptibly measurements indicate a second order phase transition from\nparamagnetic to ferromagnetic where the Curie temperature (T$_{\\rm C}$) of\nCo$_2$CrAl increases from 330~K to 445~K with Ti substitution. Neutron powder\ndiffraction data of the $x=$ 0 sample across the magnetic phase transition\ntaken in a large temperature range confirm the structural stability and exclude\nthe possibility of antiferromagnetic ordering. The saturation magnetization of\nthe $x=$ 0 sample is found to be 8000~emu/mol (1.45~$\\mu_{\\rm B}$/{\\it f.u.})\nat 5~K, which is in good agreement with the value (1.35$\\pm$0.05~$\\mu_{\\rm\nB}$/{\\it f.u.}) obtained from the Rietveld analysis of the neutron powder\ndiffraction pattern measured at temperature of 4~K. By analysing the\ntemperature dependence of the neutron data of the $x=$ 0 sample, we find that\nthe change in the intensity of the most intense Bragg peak (220) is consistent\nwith the magnetization behavior with temperature. Furthermore, an enhancement\nof change in the magnetic entropy and relative cooling power values has been\nobserved for the $x=$ 0.25 sample. Interestingly, the critical behavior\nanalysis across the second order magnetic phase transition and extracted\nexponents ($\\beta\\approx$ 0.496, $\\gamma\\approx$ 1.348, and $\\delta\\approx$\n3.71 for the $x=$ 0.25 sample) suggest the presence of long-range ordering,\nwhich deviates towards 3D Heisenberg type interactions above T$_{\\rm C}$,\nconsistent with the interaction range value $\\sigma$."
    },
    {
        "anchor": "Electric power generation of a liquid self-assembled drop on a\n  semiconductor surface: The technological innovation of the direct conversion of solar energy to\nelectric plays an important role in electric power generation. Earlier\ndiscussions of band bending in a semiconductor contacting a metal and liquid\nelectrolyte solutions containing redox couples with different electrochemical\npotentials should not overshadow the fact that under absorption of photons\ntakes place in a solar cell, which can generate free charge for an electrical\ncircuit. Here we propose new band bending of ZnO and Cu2O semiconductors\ninduced by a liquid self-assembled microdrop of a physiological salt solution.",
        "positive": "3D observations discover a new paradigm in rubber elasticity: The mechanical response of rubbers has been ubiquitously assumed to be only a\nfunction of the imposed strain. Using innovative X-ray measurements capturing\nthe three-dimensional spatial volumetric strain fields, we demonstrate that\nrubbers and indeed many common engineering polymers, undergo significant local\nvolume changes. But remarkably the overall specimen volume remains constant\nregardless of the imposed loading. This strange behaviour which also leads to\napparent negative local bulk moduli is due to the presence of a mobile phase\nwithin these materials. Combining X-ray tomographic observations with\nhigh-speed radiography to track the motion of the mobile phase we have revised\nclassical thermodynamic frameworks of rubber elasticity. The work opens new\navenues to understand not only the mechanical behaviour of rubbers but a large\nclass of widely used engineering polymers."
    },
    {
        "anchor": "Van der Waals semiconductor InSe plastifies by phase transformation: Inorganic semiconductor materials are integral to various modern\ntechnologies, yet their brittleness and limited deformability/processability\npose a significant challenge in the development of flexible, wearable, and\nminiaturized electronics. The recent discovery of room-temperature plasticity\nin a few inorganic semiconductors offers a promising pathway to address this\nchallenge, but the deformation mechanisms of these materials remain unclear.\nHere, we investigate the deformation of InSe, a two-dimensional (2D) van der\nWaals (vdW) semiconductor with substantial plasticity. By developing a\nmachine-learned deep potential, we perform atomistic simulations that capture\nthe deformation features of hexagonal InSe upon out-of-plane compression.\nSurprisingly, we discover that InSe plastifies through a so-far unrecognized\nmartensitic phase transformation; that is, the layered hexagonal structure is\nconverted to a tetragonal lattice with specific orientation relationship. This\nobservation is corroborated by high-resolution experimental observations and\ntheory. It suggests a change of paradigm, where the design of new\nplastically-deformable inorganic semiconductors should focus on compositions\nand structures that favor phase transformations rather than traditional\ndislocation slip.",
        "positive": "Modeling the evolution of representative dislocation structures under\n  high thermo-mechanical conditions during Additive Manufacturing of Alloys: Mesoscale simulations of discrete defects in metals provide an ideal\nframework to investigate the micro-scale mechanisms governing the plastic\ndeformation under high thermal and mechanical loading conditions. To bridge\nsize and time-scale while limiting computational effort, typically the concept\nof representative volume elements (RVEs) is employed. This approach considers\nthe microstructure evolution in a volume that is representative of the overall\nmaterial behavior. However, in settings with complex thermal and mechanical\nloading histories careful consideration of the impact of modeling constraints\nin terms of time scale and simulation domain on predicted results is required.\nWe address the representation of heterogeneous dislocation structure formation\nin simulation volumes using the example of residual stress formation during\ncool-down of laser powder-bed fusion (LPBF) of AISI 316L stainless steel. This\nis achieved by a series of large-scale three-dimensional discrete dislocation\ndynamics (DDD) simulations assisted by thermo-mechanical finite element\nmodeling of the LPBF process. Our results show that insufficient size of\nperiodic simulation domains can result in dislocation patterns that reflect the\nboundaries of the primary cell. More pronounced dislocation interaction\nobserved for larger domains highlight the significance of simulation domain\nconstraints for predicting mechanical properties. We formulate criteria that\ncharacterize representative volume elements by capturing the conformity of the\ndislocation structure to the bulk material. This work provides a basis for\nfuture investigations of heterogeneous microstructure formation in mesoscale\nsimulations of bulk material behavior."
    },
    {
        "anchor": "Comments on 'X-ray analysis of ZnO nanoparticles by Williamson Hall and\n  size-strain plot methods' Solid State Sciences 13 (2011) 251-256: The equation for the size strain plot methods reported by A. Khorsand Zak et\nal. (Solid State Sci. 13 (2011), 251) does not follow the dimensional\nhomogeneity, consequently leading to an inaccurate estimation of the\ncrystallite size and strain values of the materials under investigation and the\ndimensions of the obtained parameters. We also perceived an error in the values\nof crystallite size and strain reported by the authors using the size-strain\nplot method. We will discuss the importance of dimensional analysis and its\nrepercussions on the estimated values and the units of parameters.",
        "positive": "Molecular dynamic simulation of a homogeneous bcc -> hcp transition: We have performed molecular dynamic simulations of a Martensitic bcc->hcp\ntransformation in a homogeneous system. The system evolves into three\nMartensitic variants, sharing a common nearest neighbor vector along a bcc\n<111> direction, plus an fcc region. Nucleation occurs locally, followed by\nsubsequent growth. We monitor the time-dependent scattering S(q,t) during the\ntransformation, and find anomalous, Brillouin zone-dependent scattering similar\nto that observed experimentally in a number of systems above the transformation\ntemperature. This scattering is shown to be related to the elastic strain\nassociated with the transformation, and is not directly related to the phonon\nresponse."
    },
    {
        "anchor": "Hydrogenation of single-walled carbon nanotubes: Towards the development of a useful mechanism for hydrogen storage, we have\nstudied the hydrogenation of single-walled carbon nanotubes with atomic\nhydrogen using core-level photoelectron spectroscopy and x-ray absorption\nspectroscopy. We find that atomic hydrogen creates C-H bonds with the carbon\natoms in the nanotube walls and such C-H bonds can be com-pletely broken by\nheating to 600 oC. We demonstrate approximately 65+/-15 at % hydrogenation of\ncarbon atoms in the single-walled carbon nanotubes which is equivalent to\n5.1+/-1.2 weight % hydrogen capacity. We also show that the hydrogenation is a\nreversible process.",
        "positive": "Pressure-induced structural transitions in MgH${_2}$: The stability of MgH$_2$ has been studied up to 20~GPa using\ndensity-functional total-energy calculations. At ambient pressure\n$\\alpha$-MgH${_2}$ takes a TiO$_2$-rutile-type structure. $\\alpha$-MgH$_2$ is\npredicted to transform into $\\gamma$-MgH${_2}$ at 0.39~GPa. The calculated\nstructural data for $\\alpha$- and $\\gamma$-MgH${_2}$ are in very good agreement\nwith experimental values. At equilibrium the energy difference between these\nmodifications is very small, and as a result both phases coexist in a certain\nvolume and pressure field. Above 3.84~GPa $\\gamma$-MgH${_2}$ transforms into\n$\\beta$-MgH${_2}$; consistent with experimental findings. Two further\ntransformations have been identified at still higher pressure: i) $\\beta$- to\n$\\delta$-MgH${_2}$ at 6.73 GPa and (ii) $\\delta$- to $\\epsilon$-MgH${_2}$ at\n10.26~GPa."
    },
    {
        "anchor": "A Transfer Learning Approach for Microstructure Reconstruction and\n  Structure-property Predictions: Stochastic microstructure reconstruction has become an indispensable part of\ncomputational materials science, but ongoing developments are specific to\nparticular material systems. In this paper, we address this generality problem\nby presenting a transfer learning-based approach for microstructure\nreconstruction and structure-property predictions that is applicable to a wide\nrange of material systems. The proposed approach incorporates an\nencoder-decoder process and feature-matching optimization using a deep\nconvolutional network. For microstructure reconstruction, model pruning is\nimplemented in order to study the correlation between the microstructural\nfeatures and hierarchical layers within the deep convolutional network.\nKnowledge obtained in model pruning is then leveraged in the development of a\nstructure-property predictive model to determine the network architecture and\ninitialization conditions. The generality of the approach is demonstrated\nnumerically for a wide range of material microstructures with geometrical\ncharacteristics of varying complexity. Unlike previous approaches that only\napply to specific material systems or require a significant amount of prior\nknowledge in model selection and hyper-parameter tuning, the present approach\nprovides an off-the-shelf solution to handle complex microstructures, and has\nthe potential of expediting the discovery of new materials.",
        "positive": "Direct Measurement of Competing Quantum Effects on the Kinetic Energy of\n  Heavy Water upon Melting: Even at room temperature, quantum mechanics plays a major role in determining\nthe quantitative behaviour of light nuclei, changing significantly the values\nof physical properties such as the heat capacity. However, other observables\nappear to be only weakly affected by nuclear quantum effects (NQEs): for\ninstance, the melting temperatures of light and heavy water differ by less than\n4 K. Recent theoretical work has attributed this to a competition between intra\nand inter molecular NQEs, which can be separated by computing the anisotropy of\nthe quantum kinetic energy tensor. The principal values of this tensor change\nin opposite directions when ice melts, leading to a very small net quantum\nmechanical effect on the melting point. This paper presents the first direct\nexperimental observation of this phenomenon, achieved by measuring the\ndeuterium momentum distributions n(p) in heavy water and ice using Deep\nInelastic Neutron Scattering (DINS), and resolving their anisotropy. Results\nfrom the experiments, supplemented by a theoretical analysis, show that the\nanisotropy of the quantum kinetic energy tensor can also be captured for\nheavier atoms such as oxygen."
    },
    {
        "anchor": "Quasiperiodic extended Bloch states in a surface wave experiment: Bloch-like surface waves associated with a quasiperiodic structure are\nobserved for the first time in a classic wave propagation experiment which\nconsists of pulse propagation with a shallow fluid covering a quasiperiodically\ndrilled bottom. We show that a transversal pulse propagates as a plane wave\nwith quasiperiodic modulation, displaying the characteristic undulatory\npropagation in this quasiperiodic systems and reinforcing the idea that\nanalogous concepts to Bloch functions can be applied to quasicrystals under\ncertain circumstances.",
        "positive": "Evaluation of defects in cuprous oxide through exciton luminescence\n  imaging: The various decay mechanisms of excitons in cuprous oxide (Cu2O) are highly\nsensitive to defects which can relax selection rules. Here we report cryogenic\nhyperspectral imaging of exciton luminescence from cuprous oxide crystals grown\nvia the floating zone method showing the samples have few defects. Some\nlocations, however, show strain splitting of the 1s orthoexciton triplet\npolariton luminescence. Strain is reduced by annealing. In addition, annealing\ncauses annihilation of oxygen and copper vacancies, which leads to a negative\ncorrelation between luminescence of unlike vacancies."
    },
    {
        "anchor": "Quantum mechanical ab initio calculations of the structural, electronic\n  and optical properties of bulk gold nitrides: In the present work, the atomic and the electronic structures of Au3N, AuN\nand AuN2 are investigated using first-principles density-functional theory\n(DFT). We studied cohesive energy vs. volume data for a wide range of possible\nstructures of these nitrides. Obtained data was fitted to a Birch-Murnaghan\nthird-order equation of state (EOS) so as to identify the most likely\ncandidates for the true crystal structure in this subset of the infinite\nparameter space, and to determine their equilibrium structural parameters. The\nanalysis of the electronic properties was achieved by the calculations of the\nband structure and the total and partial density of states (DOS). Some possible\npressure-induced structural phase transitions have been pointed out. Further,\nwe carried out GW0 calculations within the random-phase approximation (RPA) to\nthe dielectric tensor to investigate the optical spectra of the experimentally\nsuggested modification: Au3N(D0_9). Obtained results are compared with\nexperiment and with some available previous calculations.",
        "positive": "Electronic properties of H on vicinal Pt surfaces: A first-principles\n  study: In this work, we use the first-principle density-functional approach to study\nthe electronic structure of a H atom adsorbed on the ideal Pt(111) and vicinal\nPt(211) and Pt(331) surfaces. Full three-dimensional potential-energy surfaces\n(3D PES's) as well as local electronic density of states on various adsorption\nsites are obtained. The results show that the steps modify the PES\nconsiderably. The effect is nonlocal and extends into the region of the (111)\nterraces. We also find that different type of steps have different kind of\ninfluence on the PES when compared to the one of the ideal Pt(111) surface. The\nfull 3D PES's calculated in this work provide a starting point for the\ntheoretical study of vibrational and diffusive dynamics of H adatoms adsorbed\non these vicinal surfaces."
    },
    {
        "anchor": "New 3D and 2D Octacarbon C8 and isoelectronic B4N4 having peculiar\n  mechanic and magnetic properties. First-principles identifications: Cohesive energies, energy-volume equations of states EOS, electron\nlocalization ELF maps, elastic constants, and band structures are reported for\noriginal octacarbon C8 three dimensional 3D and two-dimensional 2D chemical\nsystems based on density functional theory calculations. Specifically,\ntetragonal C8 is identified cohesive with hardness close to experimentally\nidentified cubic Ia-3 C8; both exhibiting comparable hardness to diamond. Also,\nisoelectronic and isostructural B4N4 is calculated with a slightly lower\nhardness due to the ionocovalent B-N bonding and a bandgap with the same\nmagnitude as Diamond. 2D-C8 on the other side is proposed with interpenetrating\ntwo carbon hexagonal substructures, identified from energy calculations as\nstable in a ferromagnetic ground state. Critical pressure for the collapse of\nmagnetization PC=12 GPa let assign a soft ferromagnetic behavior alike Invar\nalloys. Electronic band structures analyses identify specific bands\ndifferentiating magnetic carbon substructure (C1) from nonmagnetic\nsemi-conducting honeycomb-like C26 layers. These observations let propose spin\nchemistry perspectives once such multilayered carbon 2D compounds are grown as\nstand-alone or on selected substrates as thin or thick films",
        "positive": "Suppression of antiferromagnetic correlations by quenched dipole--type\n  impurities: The effect of quenched random ferromagnetic bonds on the antiferromagnetic\ncorrelation length of a two--dimensional Heisneberg model is studied, applying\nthe renormalization group method to the classical non--linear sigma model with\nquenched random dipole moments. It is found that the antiferromagnetic long\nrange order is destroyed for any non--zero concentration, of the dipolar\ndefects, even at zero temperature. Below a line T ~ concentration, the\ncorrelation length is independent of T, and decreases exponentially with\nconcentration. At higher temperatures, itdecays exponentially with an effective\nstiffness constant which decreases with concentration/T. The results are used\nto estimate the three--dimensional N\\'{e}el temperature, which decays linearly\nwith $x$ at small concentrations, and drops precipitously at a critical\nconcentration. These predictions are compared with experiments on doped copper\noxides, and are shown to reproduce successfully some of the prominent features\nof the data."
    },
    {
        "anchor": "Accurate Prediction of Experimental Band Gaps from Large Language\n  Model-Based Data Extraction: Machine learning is transforming materials discovery by providing rapid\npredictions of material properties, which enables large-scale screening for\ntarget materials. However, such models require training data. While automated\ndata extraction from scientific literature has potential, current\nauto-generated datasets often lack sufficient accuracy and critical structural\nand processing details of materials that influence the properties. Using band\ngap as an example, we demonstrate Large language model (LLM)-prompt-based\nextraction yields an order of magnitude lower error rate. Combined with\nadditional prompts to select a subset of experimentally measured properties\nfrom pure, single-crystalline bulk materials, this results in an automatically\nextracted dataset that's larger and more diverse than the largest existing\nhuman-curated database of experimental band gaps. Compared to the existing\nhuman-curated database, we show the model trained on our extracted database\nachieves a 19% reduction in the mean absolute error of predicted band gaps.\nFinally, we demonstrate that LLMs are able to train models predicting band gap\non the extracted data, achieving an automated pipeline of data extraction to\nmaterials property prediction.",
        "positive": "Porous Materials with Omnidirectional Negative Poisson's Ratio: This paper presents an auxetic medium, consisting of a two-dimensional\nperforated sheet where the holes are arranged in a repetitive pattern. The\nhexagonal disposition of the perforations makes the medium isotropic in the\nplane. It is shown that negative values of the Poisson's ratio can be achieved\nfor specific values of the dimensions and orientations of the holes. The\nresults of the numerical simulations are confirmed by experimental tests, in\nwhich the Poisson's ratio of each specimen examined is evaluated from the\ndisplacement field obtained from the Digital Image Correlation (DIC) technique.\nThe distribution of stresses in the medium is determined directly from\nphotoelastic images. The auxetic structure proposed in this paper is easy to\nfabricate and can be very useful in several engineering applications."
    },
    {
        "anchor": "A micromechanics-based model for stiffness and strength estimation of\n  cocciopesto mortars: The purpose of this paper is to propose an inexpensive micromechanics-based\nscheme for stiffness homogenization and strength estimation of mortars\ncontaining crushed bricks, known as cocciopesto. The model utilizes the\nMori-Tanaka method to determine the effective stiffness, combined with\nestimates of quadratic invariants of the deviatoric stresses inside phases to\npredict the compressive strength. Special attention is paid to the\nrepresentation of C-S-H gel layer around bricks and interfacial transition zone\naround sand aggregates, which renders the predictions sensitive to particle\nsizes. Several parametric studies are performed to demonstrate that the method\ncorrectly reproduces data and trends reported in available literature.\nMoreover, the model is based exclusively on parameters with clear physical or\ngeometrical meaning and as such it provides a convenient framework for its\nfurther experimental validation.",
        "positive": "Ab initio calculations of structural and electronic properties of CdTe\n  clusters: We present results of a study of small stoichiometric $Cd_{n}Te_{n}$\n($1{\\leq}n{\\leq}6$) clusters and few medium sized non-stoichiometric\n$Cd_{m}Te_{n}$ [($m,n= 13, 16, 19$); ($m{\\neq}n$)] clusters using the Density\nFunctional formalism and projector augmented wave method within the generalized\ngradient approximation. Structural properties\n  {\\it viz.} geometry, bond length, symmetry and electronic properties like\nHOMO-LUMO gap, binding energy, ionization potential and nature of bonding {\\it\netc.} have been analyzed. Medium sized non-stoichiometric clusters were\nconsidered as fragments of the bulk with T{$_{d}$} symmetry. It was observed\nthat upon relaxation, the symmetry changes for the Cd rich clusters whereas the\nTe rich clusters retain their symmetry. The Cd rich clusters develop a\nHOMO-LUMO gap due to relaxation whereas there is no change in the HOMO-LUMO gap\nof the Te rich clusters. Thus, the symmetry of a cluster seems to be an\nimportant factor in determining the HOMO-LUMO gap."
    },
    {
        "anchor": "Accommodation mechanisms in strain-transformable titanium alloys: A new $\\beta$-metastable Ti-alloy is designed with the aim to obtain a TWIP\nalloy but positioned at the limit between the TRIP/TWIP and the TWIP dominated\nregime. The designed alloy exhibits a large ductility combined with an elevated\nand stable work-hardening rate. Deformation occurring by formation and\nmultiplication of {332}<113> twins is evidenced and followed by in-situ\nelectron microscopy, and no primary stress induced martensite is observed.\nSince microstructural investigations of the deformation mechanisms show a\nhighly heterogeneous deformation, the reason of the large ductility is then\ninvestigated. The spatial strain distribution is characterized by micro-scale\ndigital image correlation, and the regions highly deformed are found to stand\nat the crossover between twins, or at the intersection between deformation\ntwins and grain boundaries. Detailed electron back-scattered imaging in such\nregions of interest finally allowed to evidence the formation of thin needles\nof stress induced martensite. The latter is thus interpreted as an\naccommodation mechanism, relaxing the local high strain fields, which ensures a\nlarge and stable plastic deformation of this newly designed Ti-alloy.",
        "positive": "Ferroic Domains of Alternating Polar and Nonpolar Orders Regulate\n  Photocurrent in Single Crystalline CH3NH3PbI3 Films Self-grown on FTO/TiO2\n  Substrate: Photovoltaic conversion efficiency (PCE) of halide perovskite solar cells has\nrisen spectacularly, yet the very crystalline structure of CH3NH3PbI3 remains\nambiguous after extensive researches, and its polar nature remains hotly\ndebated. Here we present compelling evidences that CH3NH3PbI3 crystals\nself-grown on FTO/TiO2 substrate consist of ferroic domains with alternating\npolar and nonpolar orders, in contrast to previous experimental and theoretical\nexpectations, and polar domains possess reduced photocurrent. It is found that\npolar and nonpolar orders of CH3NH3PbI3 can be distinguished from their\ndistinct lateral piezoresponse, energy dissipation, first and second harmonic\nelectromechanical couplings, and temperature variation, even though their\ndifference in crystalline lattice is very subtle, and they possess two-way\nmemory effect through cubic-tetragonal phase transition. These findings resolve\nkey questions regarding polar nature of CH3NH3PbI3 and its implication on\nphotovoltaics, reconcile contradictory data widely reported, and point a\ndirection toward engineering ferroic domains for enhanced PCE."
    },
    {
        "anchor": "Ion beam synthesis of nanothermochromic diffraction gratings with giant\n  switching contrast at telecom wavelengths: Nanothermochromic diffraction gratings based on the metal-insulator\ntransition of $\\mathrm{VO_2}$ are fabricated by site-selective ion beam\nimplantation in a $\\mathrm{SiO_2}$ matrix. Gratings were defined either (i)\ndirectly by spatially selective ion beam synthesis or (ii) by site-selective\ndeactivation of the phase transition by ion beam induced defects. The strongest\nincrease of the diffracted light intensities was observed at a wavelength of\n1550\\,nm exceeding a factor of 20 for the selectively deactivated gratings. The\nobserved pronounced thermal hysteresis extending down close to room temperature\nmakes this system ideally suited for optical memory applications.",
        "positive": "Spin Angular Momentum Transfer and Plasmogalvanic Phenomena: We introduce the continuity equation for the electromagnetic spin angular\nmomentum (SAM) in matter and discuss the torque associated with the SAM\ntransfer in terms of effective spin forces acting in a material. In plasmonic\nmetal, these spin forces result in plasmogalvanic phenomenon which is pinning\nthe plasmon-induced electromotive force to atomically-thin layer at the metal\ninterface."
    },
    {
        "anchor": "Evolutionary Method for Predicting Surface Reconstructions with Variable\n  Stoichiometry: We present a specially designed evolutionary algorithm for the prediction of\nsurface reconstructions. This new technique allows one to automatically explore\nall the low-energy configurations with variable surface atoms and variable\nsurface unit cells through the whole chemical potential range. The power of\nevolutionary search is demonstrated by the efficient identification of diamond\n2*1 (100) and 2*1 (111) surfaces with a fixed number of surface atom and a\nfixed cell size. With further variation of surface unit cells, we study the\nreconstructions of the polar surface MgO (111). Experiment has detected an\noxygen trimer (ozone) motif (Plass et al, 1998). We predict a new version of\nthis motif which can be thermodynamically stable at extreme oxygen rich\ncondition. Finally, we perform a variable stoichiometry search for a complex\nternary system: semi-polar GaN (101bar1) with and without adsorbed oxygen. The\nsearch yields a non-intuitive reconstruction based on N3-trimers. These\nexamples demonstrate that an automated scheme to explore the energy landscape\nof surfaces will improve our understanding of surface reconstructions. The\nmethod presented in this report can be generally applied to binary and\nmulti-component systems.",
        "positive": "Optical forces in nanowire pairs and metamaterials: We study the optical force arising when isolated gold nanowire pairs and\nmetamaterials with a gold nanowire pair in the unit cell are illuminated with\nlaser radiation. Firstly, we show that isolated nanowire pairs are subject to\nmuch stronger optical forces than nanospheres due to their stronger electric\nand magnetic dipole resonances. We also investigate the properties of the\noptical force as a function of the length of the nanowires and of the distance\nbetween the nanowires. Secondly, we study the optical force in a metamaterial\nthat consists of a periodic array of nanowire pairs. We show that the ratio of\nthe size of the unit cell to the length of the nanowires determines whether the\nelectric dipole resonance leads to an attractive or a repulsive force, and we\npresent the underlying physical mechanism for this effect."
    },
    {
        "anchor": "Prediction of huge X-ray Faraday rotation at the Gd N_4,5 threshold: X-ray absorption spectra in a wide energy range around the 4d-4f excitation\nthreshold of Gd were recorded by total electron yield from in-plane magnetized\nGd metal films. Matching the experimental spectra to tabulated absorption data\nreveals unprecedented short light absorption lengths down to 3 nm. The\nassociated real parts of the refractive index for circularly polarized light\npropagating parallel or antiparallel to the Gd magnetization, determined\nthrough the Kramers-Kronig transformation, correspond to a magneto-optical\nFaraday rotation of 0.7 degrees per atomic layer. This finding shall allow the\nstudy of magnetic structure and magnetization dynamics of lanthanide elements\nin nanosize systems and dilute alloys.",
        "positive": "Analyzing melts and fluids from ab initio molecular dynamics simulations\n  with the UMD package: We develop a Python-based open-source package to analyze the results stemming\nfrom ab initio molecular-dynamics simulations of fluids. The package is best\nsuited for applications on natural systems, like silicate and oxide melts,\nwater-based fluids, various supercritical fluids. The package is a collection\nof Python scripts that include two major libraries dealing with file formats\nand with crystallography. All the scripts are run at the command line. We\npropose a simplified format to store the atomic trajectories and relevant\nthermodynamic information of the simulations, which is saved in UMD files,\nstanding for Universal Molecular Dynamics. The UMD package allows the\ncomputation of a series of structural, transport and thermodynamic properties.\nStarting with the pair-distribution function it defines bond lengths, builds an\ninteratomic connectivity matrix, and eventually determines the chemical\nspeciation. Determining the lifetime of the chemical species allows running a\nfull statistical analysis. Then dedicated scripts compute the mean-square\ndisplacements for the atoms as well as for the chemical species. The\nimplemented self-correlation analysis of the atomic velocities yields the\ndiffusion coefficients and the vibrational spectrum. The same analysis applied\non the stresses yields the viscosity. The package is available via the GitHub\nwebsite and via its own dedicated page of the ERC IMPACT project as open-access\npackage."
    },
    {
        "anchor": "Degradation of Black Phosphorus (BP): The Role of Oxygen and Water: Black phosphorus (BP) has attracted significant interest as a monolayer or\nfew-layer material with extraordinary electrical and optoelectronic properties.\nHowever, degradation in air and other environments is an unresolved issue that\nmay limit future applications. In particular the role of different ambient\nspecies has remained controversial. Here, we report systematic experiments\ncombined with ab-initio calculations that address the effects of oxygen and\nwater in the degradation of BP. Our results show that BP rapidly degrades\nwhenever oxygen is present, but is unaffected by deaerated (i.e., O2 depleted)\nwater. This behavior is rationalized by oxidation involving a facile\ndissociative chemisorption of O2, whereas H2O molecules are weakly physisorbed\nand do not dissociate on the BP surface. Oxidation (by O2) turns the\nhydrophobic pristine BP surface progressively hydrophilic. Our results have\nimplications on the development of encapsulation strategies for BP, and open\nnew avenues for exploration of phenomena in aqueous solutions including\nsolution-gating, electrochemistry, and solution-phase approaches for\nexfoliation, dispersion, and delivery of BP.",
        "positive": "Ab initio molecular dynamics description of proton transfer at\n  water-tricalcium silicate interface: For the first time, an ab initio molecular dynamics simulation was performed\nto describe the C$_3$S/water interface. The simulation shows that oxides with\nfavorable environment are protonated at first, creating very stable hydroxide\ngroups. Proton transfers occur between water and silicates, and between water\nand hydroxides formed upon water dissociation on the surface. The typical\nlifetime of these events is on the same timescale than interconversion between\nEigen and Zundel ions in bulk water. At the very early stage of the hydration\nencompassed by our simulation, silanol groups are very unstable and molecular\nadsorption of water is slightly more stable than dissociative adsorption."
    },
    {
        "anchor": "Antiphase boundaries in III-V semiconductors: Atomic configurations,\n  band structures and Fermi levels: Here, we comprehensively investigate the atomic structures and electronic\nproperties of different antiphase boundaries in III-V semiconductors with\ndifferent orientations and stoichiometries, including {110}, {100}, {111},\n{112} and {113} ones, based on first-principle calculations. Especially, we\ndemonstrate how the ladder or zigzag chemical bond configuration can lead for\nthe different cases to a gapped semiconducting band structure, to a gapped\nmetallic band structure or to a non-gapped metallic band structure. Besides, we\nevidence that the ladder APB configurations impact more significantly the Fermi\nenergy levels than the zigzag APB configurations. We finally discuss how these\ndifferent band structures can have some consequences on the operation of\nmonolithic III-V/Si devices for photonics or energy harvesting.",
        "positive": "Variational Minimization of Orbital-dependent Density Functionals: Functionals that strive to correct for such self-interaction errors, such as\nthose obtained by imposing the Perdew-Zunger self-interaction correction or the\ngeneralized Koopmans' condition, become orbital dependent or orbital-density\ndependent, and provide a very promising avenue to go beyond density-functional\ntheory, especially when studying electronic, optical and dielectric properties,\ncharge-transfer excitations, and molecular dissociations. Unlike conventional\ndensity functionals, these functionals are not invariant under unitary\ntransformations of occupied electronic states, which leave the total charge\ndensity intact, and this added complexity has greatly inhibited both their\ndevelopment and their practical applicability. Here, we first recast the\nminimization problem for non-unitary invariant energy functionals into the\nlanguage of ensemble density-functional theory, decoupling the variational\nsearch into an inner loop of unitary transformations that minimize the energy\nat fixed orbital subspace, and an outer-loop evolution of the orbitals in the\nspace orthogonal to the occupied manifold. Then, we show that the potential\nenergy surface in the inner loop is far from convex parabolic in the early\nstages of the minimization and hence minimization schemes based on these\nassumptions are unstable, and present an approach to overcome such difficulty.\nThe overall formulation allows for a stable, robust, and efficient variational\nminimization of non-unitary-invariant functionals, essential to study complex\nmaterials and molecules, and to investigate the bulk thermodynamic limit, where\norbitals converge typically to localized Wannier functions. In particular,\nusing maximally localized Wannier functions as an initial guess can greatly\nreduce the computational costs needed to reach the energy minimum while not\naffecting or improving the convergence efficiency."
    },
    {
        "anchor": "Giant electrostriction in bulk RE (III) substituted CeO2: effect of RE\n  3+ and its concentration: Recent discovery of giant electrostriction in rare earth (RE (III))\nsubstituted ceria (CeO2) thin films driven by electroactive defect complexes\nand their coordinated elastic response, expands the material spectrum for\nelectrostrain applications beyond the conventional piezoelectric materials.\nEspecially Gd substituted CeO2, with Gd concentration >10% seems to be an ideal\nmaterial to obtain such large electrostrain response. However, there are not\nmany experimental studies that systematically investigate the effect of RE\n(III) ion-defect interaction and RE concentration on electrostriction. Here we\nperform structure-property correlation studies in bulk ceramics of RE3+\nsubstituted ceria doped with RE=Y, La and Gd at various concentrations upto a\nmaximum of 20%, to understand the features responsible for giant\nelectrostriction. Our results show that Y substituted ceria, with atleast 20% Y\nsubstitution, is clearly both a giant M and a Q electrostrictor at low\nfrequencies (<20 Hz), and this correlates with the unique attractive\ndefect-dopant interaction of Y with oxygen vacancies. La has a repulsive\ninteraction with oxygen vacancies, and La doped ceria at all the studied\ncompositions (upto 20%) does not show giant electrostiction. Gd has a neutral\ninteraction, and only 20% Gd doped ceria at best falls at the border of\nclassification between giant and non-giant electrostrictors at frequencies\n<0.05 Hz. Our work takes a step back from thin-films and assesses the\nfundamental defect features required in the design of giant electrostrictors.",
        "positive": "Data Storage: Review of Heusler Compounds: In the recent decade, the family of Heusler compounds has attracted\ntremendous scientific and technological interest in the field of spintronics.\nThis is essentially due to their exceptional magnetic properties, which qualify\nthem as promising functional materials in various data-storage devices, such as\ngiant-magnetoresistance spin valves, magnetic tunnel junctions, and\nspin-transfer torque devices. In this article, we provide a comprehensive\nreview on the applications of the Heusler family in magnetic data storage. In\naddition to their important roles in the performance improvement of these\ndevices, we also try to point out the challenges as well as possible solutions,\nof the current Heusler-based devices. We hope that this review would spark\nfurther investigation efforts into efficient incorporation of this eminent\nfamily of materials into data storage applications by fully arousing their\nintrinsic potential."
    },
    {
        "anchor": "3-D Tracking and Visualization of Hundreds of Pt-Co Fuel Cell\n  Nanocatalysts During Electrochemical Aging: We present an electron tomography method that allows for the identification\nof hundreds of electrocatalyst nanoparticles with one-to-one correspondence\nbefore and after electrochemical aging. This method allows us to track, in\nthree-dimensions (3-D), the trajectories and morphologies of each Pt-Co\nnanocatalyst on a fuel cell carbon support. The use of atomic-scale electron\nenergy loss spectroscopic imaging enables the correlation of performance\ndegradation of the catalyst with changes in particle/inter-particle\nmorphologies, particle-support interactions and the near-surface chemical\ncomposition. We found that, aging of the catalysts under normal fuel cell\noperating conditions (potential scans from +0.6 V to +1.0 V for 30,000 cycles)\ngives rise to coarsening of the nanoparticles, mainly through coalescence,\nwhich in turn leads to the loss of performance. The observed coalescence events\nwere found to be the result of nanoparticle migration on the carbon support\nduring potential cycling. This method provides detailed insights into how\nnanocatalyst degradation occurs in proton exchange membrane fuel cells\n(PEMFCs), and suggests that minimization of particle movement can potentially\nslow down the coarsening of the particles, and the corresponding performance\ndegradation.",
        "positive": "Controlling charge injection in organic field-effect transistors using\n  self-assembled monolayers: We have studied charge injection across the metal/organic semiconductor\ninterface in bottom-contact poly(3-hexylthiophene) (P3HT) field-effect\ntransistors, with Au source and drain electrodes modified by self-assembled\nmonolayers (SAMs) prior to active polymer deposition. By using the SAM to\nengineer the effective Au work function, we markedly affect the charge\ninjection process. We systematically examine the contact resistivity and\nintrinsic channel mobility, and show that chemically increasing the injecting\nelectrode work function significantly improves hole injection relative to\nuntreated Au electrodes."
    },
    {
        "anchor": "Quantum Transport in Air-stable Na3Bi Thin Films: Na3Bi has attracted significant interest in both bulk form as a\nthree-dimensional topological Dirac semimetal and in ultra-thin form as a\nwide-bandgap two-dimensional topological insulator. Its extreme air sensitivity\nhas limited experimental efforts on thin- and ultra-thin films grown via\nmolecular beam epitaxy to ultra-high vacuum environments. Here we demonstrate\nair-stable Na3Bi thin films passivated with magnesium difluoride (MgF2) or\nsilicon (Si) capping layers. Electrical measurements show that deposition of\nMgF2 or Si has minimal impact on the transport properties of Na3Bi whilst in\nultra-high vacuum. Importantly, the MgF2-passivated Na3Bi films are air-stable\nand remain metallic for over 100 hours after exposure to air, as compared to\nnear instantaneous degradation when they are unpassivated. Air stability\nenables transfer of films to a conventional high-magnetic field cryostat,\nenabling quantum transport measurements which verify that the Dirac semimetal\ncharacter of Na3Bi films is retained after air exposure.",
        "positive": "Stochastic Density Functional Theory at Finite Temperatures: Simulations in the warm dense matter regime using finite temperature\nKohn-Sham density functional theory (FT-KS-DFT), while frequently used, are\ncomputationally expensive due to the partial occupation of a very large number\nof high-energy KS eigenstates which are obtained from subspace diagonalization.\nWe have developed a stochastic method for applying FT-KS-DFT, that overcomes\nthe bottleneck of calculating the occupied KS orbitals by directly obtaining\nthe density from the KS Hamiltonian. The proposed algorithm, scales as\n$O\\left(NT^{-1}\\right)$ and is compared with the high-temperature limit scaling\n$O\\left(N^{3}T^{3}\\right)$ of the deterministic approach, where $N$ is the\nsystem size (number of electrons, volume etc.) and $T$ is the temperature. The\nmethod has been implemented in a plane-waves code within the local density\napproximation (LDA); we demonstrate its efficiency, statistical errors and bias\nin the estimation of the free energy per electron for a diamond structure\nsilicon. The bias is small compared to the fluctuations, and is independent of\nsystem size. In addition to calculating the free energy itself, one can also\nuse the method to calculate its derivatives and obtain the equations of state."
    },
    {
        "anchor": "Thermodynamic driving force in the formation of hexagonal-diamond Si and\n  Ge nanowires: The metastable hexagonal-diamond phase of Si and Ge (and of SiGe alloys)\ndisplays superior optical properties with respect to the cubic-diamond one. The\nlatter is the most stable and popular one: growing hexagonal-diamond Si or Ge\nwithout working at extreme conditions proved not to be trivial. Recently,\nhowever, the possibility of growing hexagonal-diamond group-IV nanowires has\nbeen demonstrated, attracting attention on such systems. Based on\nfirst-principle calculations we show that the surface energy of the typical\nfacets exposed in Si and Ge nanowires is lower in the hexagonal-diamond phase\nthan in cubic ones. By exploiting a synergic approach based also on a recent\nstate-of-the-art interatomic potential and on a simple geometrical model, we\ninvestigate the relative stability of nanowires in the two phases up to few\ntens of nm in radius, highlighting the surface-related driving force and\ndiscussing its relevance in recent experiments. We also explore the stability\nof Si and Ge core-shell nanowires with hexagonal cores (made of GaP for Si\nnanowires, of GaAs for Ge nanowires). In this case, the stability of the\nhexagonal shell over the cubic one is also favored by the energy cost\nassociated with the interface linking the two phases. Interestingly, our\ncalculations indicate a critical radius of the hexagonal shell much lower than\nthe one reported in recent experiments, indicating the presence of a large\nkinetic barrier allowing for the enlargement of the wire in a metastable phase.",
        "positive": "Anisotropic Superparamagnetism of Monodispersive Cobalt-Platinum\n  Nanocrystals: Based on the high-temperature organometallic route (Sun et al. Science 287,\n1989 (2000)), we have synthesized powders containing CoPt_3 single crystals\nwith mean diameters of 3.3(2) nm and 6.0(2) nm and small log-normal widths\nsigma=0.15(1). In the entire temperature range from 5 K to 400 K, the\nzero-field cooled susceptibility chi(T) displays significant deviations from\nideal superparamagnetism. Approaching the Curie temperature of 450(10) K, the\ndeviations arise from the (mean-field) type reduction of the ferromagnetic\nmoments, while below the blocking temperature T_b, chi(T) is suppressed by the\npresence of energy barriers, the distributions of which scale with the particle\nvolumes obtained from transmission electron microscopy (TEM). This indication\nfor volume anisotropy is supported by scaling analyses of the shape of the\nmagnetic absorption chi''(T,omega) which reveal distribution functions for the\nbarriers being also consistent with the volume distributions observed by TEM.\nAbove 200 K, the magnetization isotherms M(H,T) display Langevin behavior\nproviding 2.5(1) mu_B per CoPt_3 in agreement with reports on bulk and thin\nfilm CoPt_3. The non-Langevin shape of the magnetization curves at lower\ntemperatures is for the first time interpreted as anisotropic\nsuperparamagnetism by taking into account an anisotropy energy of the\nnanoparticles E_A(T). Using the magnitude and temperature variation of E_A(T),\nthe mean energy barriers and 'unphysical' small switching times of the\nparticles obtained from the analyses of chi''(T,omega) are explained. Below T_b\nhysteresis loops appear and are quantitatively described by a blocking model,\nwhich also ignores particle interactions, but takes the size distributions from\nTEM and the conventional field dependence of E_A into account."
    },
    {
        "anchor": "Multiple-stable anisotropic magnetoresistance memory in\n  antiferromagnetic MnTe: A common perception assumes that magnetic memories require ferromagnetic\nmaterials with a non-zero net magnetic moment. However, it has been recently\nproposed that compensated antiferromagnets with a zero net moment may represent\na viable alternative to ferromagnets. So far, experimental research has focused\non bistable memories in antiferromagnetic metals. In the present work we\ndemonstrate a multiple-stable memory device in epitaxial manganese telluride\n(MnTe) which is an antiferromagnetic counterpart of common II-VI\nsemiconductors. Favorable micromagnetic characteristics of MnTe allow us to\ndemonstrate a smoothly varying antiferromagnetic anisotropic magnetoresistance\n(AMR) with a harmonic angular dependence on the applied magnetic field,\nanalogous to ferromagnets. The continuously varying AMR provides means for the\nelectrical read-out of multiple-stable antiferromagnetic memory states which we\nset by heat-assisted magneto-recording and by changing the angle of the writing\nfield. We explore the dependence of the magnitude of the zero-field read-out\nsignal on the strength of the writing field and demonstrate the robustness of\nthe antiferromagnetic memory states against strong magnetic field\nperturbations. We ascribe the multiple-stability in our antiferromagnetic\nmemory to different distributions of domains with the N\\'eel vector aligned\nalong one of the three $c$-plane magnetic easy axes in the hexagonal MnTe film.\nThe domain redistribution is controlled during the heat-assisted recording by\nthe strength and angle of the writing field and freezes when sufficiently below\nthe N\\'eel temperature.",
        "positive": "Electric-field induced polarization paths in PZT alloys: Properties of Pb(Zr_{1-x}Ti_x)O_3 (PZT) for compositions x near the\nmorphotropic phase boundary and under an electric field are simulated using an\nab-initio based approach. Applying an electric field of [111] orientation to\ntetragonal PZT (e.g., x=0.50) leads to the expected sequence of tetragonal,\nA-type monoclinic, and rhombohedral structures. However, the application of a\nfield of orientation [001] to rhombohedral PZT (e.g., x=0.47) does not simply\nreverse this sequence. Instead, the system follows a complicated path involving\nalso triclinic and C-type monoclinic structures. These latter phases are found\nto exhibit huge shear piezoelectric coefficients."
    },
    {
        "anchor": "Reversed anisotropies and thermal contraction of FCC (110) surfaces: The observed anisotropies of surface vibrations for unreconstructed FCC metal\n(110) surfaces are often reversed from the \"common sense\" expectation. The\nsource of these reversals is investigated by performing ab initio density\nfunctional theory calculations to obtain the surface force constant tensors for\nAg(110), Cu(110) and Al(110). The most striking result is a large enhancement\nin the coupling between the first and third layers of the relaxed surface,\nwhich strongly reduces the amplitude of out-of-plane vibrations of atoms in the\nfirst layer. This also provides a simple explanation for the thermal\ncontraction of interlayer distances. Both the anisotropies and the thermal\ncontraction arise primarily as a result of the bond topology, with all three\n(110) surfaces showing similar behavior.",
        "positive": "Evidence of valence band perturbations in GaAsN/GaAs(001): A combined\n  variable-angle spectroscopic ellipsometry and modulated photoreflectance\n  investigation: The contribution of the fundamental gap E_ as well as those of the E_ +\nDelta(so) and E+ transitions to the dielectric function of GaAs1-xNx alloys\nnear the band edge were determined from variable-angle spectroscopic\nellipsometry and modulated photoreflectance spectroscopy analyses. The\noscillator strength of the E_ optical transition increases weakly with nitrogen\nincorporation. The two experimental techniques independently reveal that not\nonly the oscillator strength of the E+ transition but also that of E_ +\nDelta(so) become larger compared to that of the fundamental gap as the N\ncontent increases. Since the same conduction band is involved in both the E_\ntransition and its split-off replica, these results reveal that adding nitrogen\nin GaAs1-xNx alloys affects not only the conduction but also the valence bands."
    },
    {
        "anchor": "The impact of stress on the electronic structure of phosphorus\n  allotropes stacked on hexagonal boron nitride: We study the mechanical and electronic properties of heterobilayers composed\nof black phosphorus (BP) on hexagonal boron nitride (hBN) and of blue\nphosphorus (\\Pblue) on hBN by means of ab-intio density functional theory.\nEmphasis is put on how the stress applied on the constituent layers impact\ntheir structural and electronic properties. For this purpose, we adopt a\nspecific scheme of structural relaxation which allows us to distinguish between\nthe energy cost of distorting each layer and the gain in stacking them\ntogether. In most cases we find that the BP tends to contract along the softer\narmchair direction, as already reported for similar structures. This\ncontraction can attain up to 5\\% of strain, which might deteriorate its very\ngood transport properties along the armchair direction. To prevent this, we\npropose a twisted-bilayer configuration where the largest part of the stress\napplies on the zigzag axis, resulting in a lower impact on the transport\nproperties of BP. We also investigated a \\Pblue/hBN bilayer. A peculiar\nhybridization between the valence states of the two layers lets us suggest that\nelectron-hole pairs excited in the bilayer will exhibit a mixed character, with\nelectrons localized solely in the \\Pblue{ }layer, and holes spread onto the two\nlayers.",
        "positive": "A coupled approach to predict cone-cracks in spherical indentation tests\n  with smooth or rough indenters: Indentation tests are largely exploited in experiments to characterize the\nmechanical and fracture properties of the materials from the resulting crack\npatterns. This work proposes an efficient theoretical and computational\nframework, whose implementation is detailed for 2D axisymmetric and 3D\ngeometries, to simulate indentation-induced cracking phenomena caused by\nnon-conforming contacts with indenter profiles of arbitrary shape. The\nformulation hinges on the coupling of the MPJR (eMbedded Profile for Joint\nRoughness) interface finite elements which embed the indenter profile to solve\nthe contact problem between non-planar bodies efficiently and the phase-field\nfor brittle fracture to simulate crack evolution and nonlocal damage in the\nsubstrate. The novel framework is applied to predict cone-crack formation in\nthe case of indentation tests with smooth spherical indenters, with validation\nagainst experimental data. Then, the methodology is employed for the very first\ntime in the literature to assess the effect of surface roughness superimposed\non the shape of the smooth spherical indenter. In terms of physical insights,\nnumerical predictions quantify the dependencies of the critical load for crack\nnucleation and the crack radius on the amplitude of roughness in comparison\nwith the behavior of smooth indenters. Again, the consistency with available\nexperimental trends is noticed."
    },
    {
        "anchor": "PbTi1-xPdxO3: A New Room-temperature Magnetoelectric Multiferroic Device\n  Material: There have been a large number of papers on bismuth ferrite (BiFeO3) over the\npast few years, trying to exploit its room-temperature magnetoelectric\nmultiferroic properties. Although these are attractive, BiFeO3 is not the ideal\nmultiferroic, due to weak magnetization and the difficulty in limiting leakage\ncurrents. Thus there is an ongoing search for alternatives, including such\nmaterials as gallium ferrite (GaFeO3). In the present work we report a\ncomprehensive study of the perovskite PbTi1-xPdxO3 with 0 < x < 0.3. Our study\nincludes dielectric, impedance and magnetization measurements, conductivity\nanalysis and study of crystallographic phases present in the samples with\nspecial attention paid to minor phases, identified as PdO, PbPdO2, and Pd3Pb.\nThe work is remarkable in two ways: Pd is difficult to substitute into ABO3\nperovskite oxides (where it might be useful for catalysis), and Pd is magnetic\nunder only unusual conditions (under strain or internal electric fields). The\nnew material, as a PZT derivative, is expected to have much stronger\npiezoelectric properties than BiFeO3.",
        "positive": "Elastic properties and electronic structures of antiperovskite-type\n  InNCo3 and InNNi3: We have performed the first-principles calculations to study the elasticity,\nelectronic structure, and magnetism of InNCo3 and InNNi3. The independent\nelastic constants are derived from the second derivative of total energy as a\nfunction of strain, and the elastic modulus are predicted according to the\nVoigt-Reuss-Hill approximation. Our calculations show that the bulk modulus of\nInNCo3 is slightly larger than that of InNNi3. For InNCo3 the ferromagnetic\nstate is energetically preferable to the paramagnetic state, while the ground\nstate of InNNi3 is a stable paramagnetic (non-magnetic) state. This is due to\nthe different strength of 2p-3d hybridization for the N-Co and N-Ni atoms in\nInNCo3 and InNNi3."
    },
    {
        "anchor": "Understanding Trap States in InP and GaP Quantum Dots Through Density\n  Functional Theory: The widespread application of III-V colloidal quantum dots (QDs) as\nnon-toxic, highly tunable emitters is stymied by their high density of trap\nstates. Here, we utilize density functional theory (DFT) to investigate trap\nstate formation in a diverse set of realistically passivated core-only InP and\nGaP QDs. Through orbital localization techniques, we deconvolute the dense\nmanifold of trap states to allow for detailed assignment of surface defects. We\nfind that the three-coordinate species dominate trapping in III-V QDs and\nidentify features in the geometry and charge environment of trap centers\ncapable of deepening, or sometimes passivating, traps. Furthermore, we observe\nstark differences in surface reconstruction between InP and GaP, where the more\nlabile InP reconstructs to passivate three-coordinate indium at the cost of\ndistortion elsewhere. These results offer explanations for experimentally\nobserved trapping behavior and suggest new avenues for controlling trap states\nin III-V QDs.",
        "positive": "Resistive Switching in Nanodevices: Passing current at given threshold voltages through a metal/insulator/metal\nsandwich structure device may change its resistive state. Such resistive\nswitching is unique to nanoscale devices, but its underlying physical mechanism\nremains unknown. We show that the different resistive states are due to\ndifferent spontaneously charged states, characterized by different `band\nbending' solutions of Poisson's equation. For an insulator with mainly donor\ntype defects, the low-resistivity state is characterized by a negatively\ncharged insulator due to convex band bending, and the high-resistivity state by\na positively charged insulator due to concave band bending; vice versa for\ninsulators with mainly acceptor type defects. These multiple solutions coexist\nonly for nanoscale devices and for bias voltages limited by the switching\nthreshold values, where the system charge spontaneously changes and the system\nswitches to another resistive state. We outline the general principles how this\nfunctionality depends on material properties and defect abundance of the\ninsulator `storage medium', and propose a new magnetic memristor device with\nincreased storage capacity."
    },
    {
        "anchor": "Development of various methods for PrF3 nanoparticles synthesis: The six nanosized PrF3 samples were synthesized using two different chemical\nreactions and different time of hydrothermal reaction. The X-ray and HRTEM\nexperiments showed high crystallinity of synthesized samples. For all samples\nthe particles size distribution was obtained. It was shown, that precursors of\nchemical reaction have influence on the shape of synthesized nanoparticles. The\nsize of nanoparticles depended on the time of hydrothermal reaction as much as\nroughly 10 nm per hour.",
        "positive": "Tripling energy storage density through order-disorder transition\n  induced polar nanoregions in PbZrO3 thin films by ion implantation: Dielectric capacitors are widely used in pulsed power electronic devices due\nto their ultrahigh power densities and extremely fast charge/discharge speed.\nTo achieve enhanced energy storage density, both maximum polarization (Pmax)\nand breakdown strength (Eb) need to be improved simultaneously. However, these\ntwo key parameters are inversely correlated. In this study, order-disorder\ntransition induced polar nanoregions (PNRs) have been achieved in PbZrO3 thin\nfilms by making use of the low-energy ion implantation, enabling us overcome\nthe trade-off between high polarizability and breakdown strength, which leads\nto the tripling of the energy storage density from 20.5 J/cm3 to 62.3 J/cm3 as\nwell as the great enhancement of breakdown strength. This approach could be\nextended to other dielectric oxides to improve the energy storage performance,\nproviding a new pathway for tailoring the oxide functionalities."
    },
    {
        "anchor": "Infrared dielectric functions and Brillouin zone center phonons of\n  $\u03b1$-Ga$_2$O$_3$ compared to $\u03b1$-Al$_2$O$_3$: We determine the anisotropic dielectric functions of rhombohedral\n$\\alpha$-Ga$_2$O$_3$ by far-infrared and infrared generalized spectroscopic\nellipsometry and derive all transverse optical and longitudinal optical phonon\nmode frequencies and broadening parameters. We also determine the high\nfrequency and static dielectric constants. We perform density functional theory\ncomputations and determine the phonon dispersion for all branches in the\nBrillouin zone, and we derive all phonon mode parameters at the Brillouin zone\ncenter including Raman-active, infrared-active, and silent modes. Excellent\nagreement is obtained between our experimental and computation results as well\nas among all previously reported partial information from experiment and\ntheory. We also compute the same information for $\\alpha$-Al$_2$O$_3$, the\nbinary parent compound for the emerging alloy of\n$\\alpha$-(Al$_{x}$Ga$_{1-x}$)$_2$O$_3$, and use results from previous\ninvestigations [Schubert, Tiwald, and Herzinger, Phys. Rev. B 61, 8187 (2000)]\nto compare all properties among the two isostructural compounds. From both\nexperimental and theoretical investigations we compute the frequency shifts of\nall modes between the two compounds. Additionally, we calculate overlap\nparameters between phonon mode eigenvectors and discuss the possible evolution\nof all phonon modes into the ternary alloy system and whether modes may form\nsingle mode or more complex mode behaviors.",
        "positive": "Phase field theory of polycrystalline solidification in three dimensions: A phase field theory of polycrystalline solidification is presented that is\nable to describe the nucleation and growth of anisotropic particles with\ndifferent crystallographic orientation in three dimensions. As opposed with the\ntwo-dimensional case, where a single orientation field suffices, in three\ndimensions, minimum three fields are needed. The free energy of grain\nboundaries is assumed to be proportional to the angular difference between the\nadjacent crystals expressed here in terms of the differences of the four\nsymmetric Euler parameters. The equations of motion for these fields are\nobtained from variational principles. Illustrative calculations are performed\nfor polycrystalline solidification with dendritic, needle and spherulitic\ngrowth morphologies."
    },
    {
        "anchor": "Tuning of magnetic and electronic states by control of oxygen content in\n  lanthanum strontium cobaltites: We report on the magnetic, resistive, and structural studies of perovskite\nLa$_{1/3}$Sr$_{2/3}$CoO$_{3-\\delta}$. By using the relation of synthesis\ntemperature and oxygen partial pressure to oxygen stoichiometry obtained from\nthermogravimetric analysis, we have synthesized a series of samples with\nprecisely controlled $\\delta=0.00-0.49$. These samples show three structural\nphases at $\\delta=0.00-0.15$, $\\approx0.25$, $\\approx0.5$, and two-phase\nbehavior for other oxygen contents. The stoichiometric material with\n$\\delta=0.00$ is a cubic ferromagnetic metal with the Curie temperature $T_{\\rm\nC}=274$ K. The increase of $\\delta$ to 0.15 is followed by a linear decrease of\n$T_{\\rm C}$ to $\\approx$ 160 K and a metal-insulator transition near the\nboundary of the cubic structure range. Further increase of $\\delta$ results in\nformation of a tetragonal $2a_p\\times 2a_p \\times 4a_p$ phase for\n$\\delta\\approx 0.25$ and a brownmillerite phase for $\\delta\\approx0.5$. At low\ntemperatures, these are weak ferromagnetic insulators (canted antiferromagnets)\nwith magnetic transitions at $T_{\\rm m}\\approx230$ and 120 K, respectively. At\nhigher temperatures, the $2a_p\\times 2a_p \\times 4a_p$ phase is $G$-type\nantiferromagnetic between 230 K and $\\approx$360 K. Low temperature magnetic\nproperties of this system for $\\delta<1/3$ can be described in terms of a\nmixture of Co$^{3+}$ ions in the low-spin state and Co$^{4+}$ ions in the\nintermediate-spin state and a possible spin transition of Co$^{3+}$ to the\nintermediate-spin state above $T_{\\rm C}$. For $\\delta>1/3$, there appears to\nbe a combination of Co$^{2+}$ and Co$^{3+}$ ions, both in the high-spin state\nwith dominating antiferromagnetic interactions.",
        "positive": "Computational generation of voids in $a$-Si and $a$-Si:H by cavitation\n  at low density: Use of amorphous silicon ($a$-Si) and hydrogenated amorphous silicon\n($a$-Si:H) in photovoltaics has been limited by light-induced degradation (the\nStaebler-Wronski effect) and low hole mobilities, and voids have been\nimplicated in both problems. Accurately modeling the void microstructure is\ncritical to theoretically understanding the cause of these issues. Previous\nmethods of modeling voids have involved removing atoms according to an {\\it a\npriori} idea of void structure and/or using computationally expensive molecular\ndynamics. We propose a new fast and unbiased approach based on the established\nand efficient Wooten-Winer-Weaire (WWW) Monte Carlo method, by using a range of\nfixed densities to generate equilibrium structures of $a$-Si and $a$-Si:H that\nmaintain 4-coordination. We find a smooth evolution in bond lengths, bond\nangles, and bond angle deviations $\\Delta \\theta$ as the density is changed\naround the equilibrium value of $4.9\\times10^{22}\\ $atoms/cm$^3$. However, a\nsignificant change occurs at densities below $4.3\\times10^{22}\\ $atoms/cm$^3$,\nwhere voids begin to form to relieve tensile stress, akin to a cavitation\nprocess in liquids. We find both small voids (radius $\\sim$3 \\AA) and larger\nones (up to 7 \\AA), which compare well with available experimental data. The\nvoids have an influence on atomic structure up to 4 \\AA beyond the void surface\nand are associated with decreasing structural order, measured by\n$\\Delta\\theta$. We also observe an increasing medium-range dihedral order with\nincreasing density. Our method allows fast generation of statistical ensembles,\nresembles a physical process during experimental deposition, and provides a set\nof void structures for further studies of their effects on degradation, hole\nmobility, two-level systems, thermal transport, and elastic properties."
    },
    {
        "anchor": "Charge-order phase transition in the quasi one-dimensional organic\n  conductor (TMTTF)$_2$NO$_3$: Low-dimensional organic conductors show a rich phase diagram, which has,\ndespite all efforts, still some unexploed regions. Charge ordered phases\npresent in many compounds of the (TMTTF)$_2 X$ family are typically studied\nwith their unique electronic properties in mind. An influence on the spin\narrangement is, however, not expected at first glance. Here, we report\ntemperature and angle dependent electron spin resonance (ESR) measurements on\nthe quasi one-dimensional organic conductor (TMTTF)$_2$NO$_3$. We found that\nthe (TMTTF)$_2$NO$_3$ compound develops a peculiar anisotropy with a doubled\nperiodicity ($ab'$-plane) of the ESR linewidth below about $T_\\text{CO}=250\\pm\n10$ K. This behavior is similar to observations in the related compounds\n(TMTTF)$_2 X$ ($X$ = PF$_6$, SbF$_6$ and AsF$_6$), where it has been attributed\nto relaxation processes of magnetically inequivalent sites in the\ncharge-ordered state. For the structural analogous (TMTTF)$_2$ClO$_4$, known\nfor the absence of charge order, such angular dependence of the ESR signal is\nnot observed. Therefore, our ESR measurements lead us to conclude that a\ncharge-order phase is stabilized in the title compound below $T_\\text{CO}\n\\approx 250$ K.",
        "positive": "High-Level Correlated Approach to the Jellium Surface Energy, Without\n  Uniform-Electron-Gas Input: We resolve the long-standing controversy over the surface energy of simple\nmetals: Density functional methods that require uniform-electron-gas input\nagree with each other at many levels of sophistication, but not with high-level\ncorrelated calculations like Fermi Hypernetted Chain and Diffusion Monte Carlo\n(DMC) that predict the uniform-gas correlation energy. Here we apply a very\nhigh-level correlated approach, the inhomogeneous Singwi-Tosi-Land-Sj\\\"olander\n(ISTLS) method, and find that the density functionals are indeed reliable\n(because the surface energy is \"bulk-like\"). ISTLS values are close to\nrecently-revised DMC values. Our work also vindicates the previously-disputed\nuse of uniform-gas-based nonlocal kernels in time-dependent density functional\ntheory."
    },
    {
        "anchor": "Detailed Electron Energy Loss Spectroscopy (EELS) Microanalysis of Data\n  Collected Under Semi-Angle Less Than Both Plasmon Cutoff Angle and Incident\n  Beam Convergence Semi-Angle: In previous work a different and powerful, analytical, technique was used to\nget data, such as the absolute atom concentration (AAC), specimen thickness\netc., from public domain boron nitride EELS spectrum collected under a\ncollection semi-angle, $\\beta$, less than the plasmon cutoff angle,\n$\\theta_{c}$, but large relative to incident beam convergence, $\\alpha$. Here,\nseeking for some completeness, another, numerical, technique usable together\nwith, also, $\\beta < \\theta_{c}$ is described in minute detail and applied to\ndata obtained with $\\beta/\\alpha < 2$, so necessitating incident beam\nconvergence-related corrections. A lot of experimental physical parameters all\nfully relevant to one another are produced from a single EELS spectrum. Of\npublic domain silicon nitride, Si$_{3}$N$_{4}$, EELS spectrum used. Comparison\nbetween results producible by the two $\\beta<\\theta_{c}$-related techniques\nmade. Results range from parameters such as AAC, density, plasmon critical\nvector, plasmon dispersion coefficient, Fermi energy to specimen thickness.\nResults were obtained using version 5 of eelsMicr program and compared with\nexisting results obtained using non EELS techniques.",
        "positive": "Peculiarities of the local structure in new medium- and high-entropy,\n  low-symmetry tungstates: New monoclinic ($P2$/$c$) tungstates - a medium-entropy tungstate,\n(Mn,Ni,Cu,Zn)WO$_4$, and a high-entropy tungstate, (Mn,Co,Ni,Cu,Zn)WO$_4$ -\nwere synthesized and characterized. Their phase purity and solid solution\nnature were confirmed by powder X-ray diffraction and Raman spectroscopy. X-ray\nabsorption spectroscopy was used to probe the local structure around metal\ncations. The atomic structures based on the ideal solid solution model were\noptimized by a simultaneous analysis of the extended X-ray absorption fine\nstructure spectra at multiple metal absorption edges - five for\n(Mn,Ni,Cu,Zn)WO$_4$ and six for (Mn,Co,Ni,Cu,Zn)WO$_4$ - by means of reverse\nMonte Carlo simulations. In both compounds, Ni$^{2+}$ ions have the strongest\ntendency to organize their local environment and form slightly distorted\n[NiO$_6$] octahedra, whereas Mn$^{2+}$, Co$^{2+}$, and Zn$^{2+}$ ions have a\nstrongly distorted octahedral coordination. The most intriguing result is that\nthe shape of [CuO$_6$] octahedra in (Mn,Ni,Cu,Zn)WO$_4$ and\n(Mn,Co,Ni,Cu,Zn)WO$_4$ differs from that found in pure CuWO$_4$, where a strong\nJahn-Teller distortion is present: [CuO$_6$] octahedra become more regular with\nincreasing degree of dilution."
    },
    {
        "anchor": "Spin reorientation behavior in YMn1-xMxO3 (M = Ti, Fe, Ga; x = 0, 0.1): The structural and magnetic properties of polycrystalline YMn1-xMxO3 (M = Ti,\nFe, Ga; x = 0, 0.1) have been studied by neutron powder diffraction and\nmagnetic measurements to probe the effect of Mn site doping on the frustration\nbehavior and magnetic structure of these compounds. The compounds are\nisostructural and crystallize with hexagonal structure in P63cm space group. We\nfind that doping with these three ions, Ti4+ (d0), Fe3+ (d5) and Ga3+ (d10),\ninfluences both the TN and magnetic structure, unlike other Mn-site dopants\nreported previously. The magnetic structure of YMnO3 is described by\nconsidering a linear combination of irreducible representations {\\Gamma}3 and\n{\\Gamma}4 below TN ~ 75K and with decrease in temperature the ratio of\n{\\Gamma}3 and {\\Gamma}4 changes. The mixing ratio of these two irreducible\nrepresentations remains constant on lowering of temperature in the Ga doped\ncompounds. The magnetic structure is modified on doping with nonmagnetic ion\nTi4+ (d0). It is described by the basis vectors of the irreducible\nrepresentation {\\Gamma}2 with moment 2.3{\\mu}B at 6 K. On doping with Fe3+ (d5)\nthe magnetic structure immediately below TN is explained by considering the\n{\\Gamma}3 irreducible representation. On further lowering of temperature, a\nspin reorientation at ~ 35 K is observed. Below this temperature, the magnetic\nstructure of YMn0.9Fe0.1O3 is explained by considering {\\Gamma}3 representation\nwith 51% mixing of {\\Gamma}4. The ordered moments are found to be reduced from\nthe expected value for a Mn3+ ion in all these compounds indicating the\nfrustrated nature of these compounds. However, the frustration parameter, f is\nsignificantly reduced in the case of Ti doped compound with {\\Gamma}2\nrepresentation.",
        "positive": "Size effects in the thin films of order - disorder ferroelectrics\n  subject to the depolarization field: The films of order-disorder type ferroelectrics were considered in the mean\nfield approximation taking into account depolarization field. It was shown that\nsize effects in this system could be described on the base of bulk system\nequation of state with Curie temperature dependent on the film thickness. The\ncritical size hc and critical temperature Tc of phase transition from\nferroelectric to paraelectric phase was calculated allowing for the\ndepolarization field contribution. The comparison of the polarization\ndependence on the film thickness, temperature and electric field for the films\nof order-disorder and displacement type ferroelectrics is performed. In\nparticular it was shown that all the dipoles become ordered at T=0\nindependently on the film thickness for h>hc contrary to the displacement type\nferroelectrics. Critical thickness appeared larger and polarization\ndistribution sharper for the displacement type ferroelectrics than for\norder-disorder type ferroelectrics."
    },
    {
        "anchor": "Tunneling Electroresistance Induced by Interfacial Phase Transitions in\n  Ultrathin Oxide Heterostructures: The ferroelectric (FE) control of electronic transport is one of the emerging\ntechnologies in oxide heterostructures. Many previous studies in FE tunnel\njunctions (FTJs) exploited solely the differences in the electrostatic\npotential across the FTJs that are induced by changes in the FE polarization\ndirection. Here, we show that in practice the junction current ratios between\nthe two polarization states can be further enhanced by the electrostatic\nmodification in the correlated electron oxide electrodes, and that FTJs with\nnanometer thin layers can effectively produce a considerably large\nelectroresistance ratio at room temperature. To understand these surprising\nresults, we employed an additional control parameter, which is related to the\ncrossing of electronic and magnetic phase boundaries of the correlated electron\noxide. The FE-induced phase modulation at the heterointerface ultimately\nresults in an enhanced electroresistance effect. Our study highlights that the\nstrong coupling between degrees of freedom across heterointerfaces could yield\nversatile and novel applications in oxide electronics.",
        "positive": "Giant switchable Rashba effect in oxide heterostructures: One of the most fundamental phenomena and a reminder of the electron's\nrelativistic nature is the Rashba spin splitting for broken inversion symmetry.\nUsually this splitting is a tiny relativistic correction, hardly discernible in\nexperiment. Interfacing a ferroelectric, BaTiO$_3$, and a heavy 5$d$ metal with\na large spin-orbit coupling, Ba(Os,Ir)O$_3$, we show that giant Rashba spin\nsplittings are indeed possible and even fully controllable by an external\nelectric field. Based on density functional theory and a microscopic tight\nbinding understanding, we conclude that the electric field is amplified and\nstored as a ferroelectric Ti-O distortion which, through the network of oxygen\noctahedra, also induces a large Os-O distortion. The BaTiO$_3$/BaOsO$_3$\nheterostructure is hence the ideal test station for studying the fundamentals\nof the Rashba effect. It allows intriguing application such as the Datta-Das\ntransistor to operate at room temperature."
    },
    {
        "anchor": "Observation of Phase Controllable Majorana-like Bound States in\n  Metamaterial-based Kitaev Chain Analogues: We experimentally demonstrate that Majorana-like bound states (MLBSs) can\noccur in quasi-one-dimensional metamaterials, analogous to Majorana zero modes\n(MZM) in the Kitaev chain. In a mechanical spinner ladder system, we observe a\ntopological phase transition and spectral-gap-protected edge MLBSs. We\ncharacterize the decaying and oscillatory nature of these MLBS pairs and their\nphase-dependent hybridization. It is shown that the hybridization can be tuned\nto yield the analogue of parity switching in MZMs, a key element of topological\nqubits. We find strong agreements with theory.",
        "positive": "Tunable Chirality-dependent Nonlinear Electrical Responses in 2D\n  Tellurium: Tellurium (Te) is an elemental semiconductor with a simple chiral crystal\nstructure. Te in a two-dimensional (2D) form synthesized by solution-based\nmethod shows excellent electrical, optical, and thermal properties. In this\nwork, the chirality of hydrothermally grown 2D Te is identified and analyzed by\nhot sulfuric acid etching and high-angle tilted high-resolution scanning\ntransmission electron microscopy. The gate-tunable nonlinear electrical\nresponses, including the nonreciprocal electrical transport in the longitudinal\ndirection and the nonlinear planar Hall effect in the transverse direction, are\nobserved in 2D Te under a magnetic field. Moreover, the nonlinear electrical\nresponses have opposite signs in left- and right-handed 2D Te due to the\nopposite spin polarizations ensured by the chiral symmetry. The fundamental\nrelationship between the spin-orbit coupling and the crystal symmetry in two\nenantiomers provides a viable platform for realizing chirality-based electronic\ndevices by introducing the chirality degree of freedom into electron transport."
    },
    {
        "anchor": "Contact effects in polymer field-effect transistors: Contact resistances often contribute significantly to the overall device\nresistance in organic field-effect transistors (OFETs). Understanding charge\ninjection at the metal-organic interface is critical to optimizing OFET device\nperformance. We have performed a series of experiments using bottom-contact\npoly(3-hexylthiophene) (P3HT) OFETs in the shallow channel limit to examine the\ninjection process. When contacts are ohmic we find that contact resistivity is\ninversely proportional to carrier mobility, consistent with diffusion-limited\ninjection. However, data from devices with other electrode materials indicate\nthat this simple picture is inadequate to describe contacts with significant\nbarriers. A generalized transmission line method allows the analysis of\nnonohmic contacts, and we find reasonable agreement with a model for injection\nthat accounts for the hopping nature of conduction in the polymer. Variation of\nthe (unintentional) dopant concentration in the P3HT can significantly alter\nthe injection process via changes in metal-organic band alignment. At very low\ndoping levels, transport suggests the formation of a barrier at the Au/P3HT\ninterface, while Pt/P3HT contacts remain ohmic with comparatively low\nresistance. We recently observed that self-assembled monolayers on the metal\nsource/drain electrodes can significantly decrease contact resistance and\nmaintain ohmic conduction under conditions that would result in nonohmic, high\nresistance contacts to untreated electrodes. Finally, we discuss measurements\non extremely short channel devices, in the initial steps toward examining\ntransport through individual polymer chains.",
        "positive": "Connecting diffusion and dynamical heterogeneities in actively deformed\n  amorphous systems: We present an extensive numerical study of dynamical heterogeneities and\ntheir influence on diffusion in an athermal mesoscopic model for actively\ndeformed amorphous solids. At low strain rates the stress dynamics are governed\nby cooperative regions of plastic events. On the basis of scaling arguments as\nwell as an extensive numerical study of an athermal elasto-plastic model, we\nshow that there is a direct link between the self-diffusion coefficient and the\nsize of cooperative regions at low strain rates. Both depend strongly on rate\nand on system size. A measure of the mean square displacement of passive\ntracers in deformed amorphous media thus gives information about the\nmicroscopic rheology, such as the geometry of the cooperative regions and their\nscaling with strain rate and system size."
    },
    {
        "anchor": "Optically controlled single-valley exciton doublet states with tunable\n  internal spin structures and spin magnetization generation: Manipulating quantum states through light-matter interactions has been\nactively pursued in two-dimensional (2D) materials research. Significant\nprogress has been made towards the optical control of the valley degrees of\nfreedom in semiconducting monolayer transition-metal dichalcogenides (TMD),\nbased on doubly degenerate excitons from their two distinct valleys in\nreciprocal space. Here, we introduce a novel kind of optically controllable\ndoubly degenerate exciton states that come from a single valley, dubbed as\nsingle-valley exciton doublet (SVXD) states. They are unique in that their\nconstituent holes originate from the same valence band, making possible the\ndirect optical control of the spin structure of the excited constituent\nelectrons. Combining ab initio GW plus Bethe-Salpeter equation (GW-BSE)\ncalculations and a newly developed theoretical analysis method, we demonstrate\nsuch novel SVXD in substrate-supported monolayer bismuthene -- which has been\nsuccessfully grown using molecular beam epitaxy. In each of the two distinct\nvalleys in the Brillouin zone, strong spin-orbit coupling and $C_{3v}$ symmetry\nlead to a pair of degenerate 1s exciton states (the SVXD states) with opposite\nspin configurations. Any coherent linear combinations of the SVXD in a single\nvalley can be excited by light with a specific polarization, enabling full\nmanipulation of their internal spin configurations. In particular, a\ncontrollable net spin magnetization can be generated through light excitation.\nOur findings open new routes to control quantum degrees of freedom, paving the\nway for applications in spintronics and quantum information science.",
        "positive": "Necessary and Sufficient Elastic Stability Conditions in Various Crystal\n  Systems: While the Born elastic stability criteria are well-known for cubic crystals,\nthere is some confusion in the literature about the form it should take for\nlower symmetry crystal classes. We present here closed form necessary and\nsufficient conditions for elastic stability in all crystal classes, as a\nconcise and pedagogical reference to stability criteria in non-cubic materials."
    },
    {
        "anchor": "Field-angle dependence of sound velocity in the Weyl semimetal TaAs: The elastic modulus $c_{44}$ of a single crystal of the Weyl semimetal TaAs\nwas investigated by measuring relative changes in the sound velocity under\napplication of a magnetic field up to 10 T. Using an ultrasonic pulsed-echo\ntechnique, we studied the shear response of the crystal when the angle between\nthe sound wave propagation and the magnetic field is changed. We observe a\nbroken tetragonal symmetry at fields above 6 T, an anisotropy that is likely\nrelated to a longitudinal negative magnetoresistance and therefore might\nprovide evidence of the chiral anomaly, one of the main topological signatures\nof this class of materials. We also observe quantum oscillations in the sound\nvelocity whose frequencies vary with magnetic field orientation. A fan diagram\nof Landau level indices reveals topological and trivial Berry phases, depending\non the field orientation, indicating a sensitivity to different Fermi surface\npockets that do or do not enclose Weyl nodes respectively.",
        "positive": "Determination of the Ignorable Boundary Condition and Standard Sample\n  for A Novel in-situ Dynamic Mechanical Analysis Method on Soft Matter: An in-situ Dynamic Mechanical Analysis (DMA) method for soft matter developed\nby our group [Wu. et.al. 2022] encounters the problem of irregular samples,\nwhich significantly vary in shape and size in practice, therefore a standard\nsample \"large enough\" to ignore the boundary and size effects is necessary to\ndetermine the baseline of test and build the correspondence between this new\nmethod to classical mechanical tests. In this work, we use finite element\nanalysis to approach the optimal size of a brick sample where the stress on the\nboundaries in three spatial directions are ignorable, and certified the results\nby testing a series of silicone gel samples on the in-situ DMA device. The\nstress-strain of tensile and compression are characterized. The material\nproperties of gel are chosen to be close to the biological soft tissue. The\nsize of 40mm(L)*40mm(W)*20mm(H) is determined to be the optimal result."
    },
    {
        "anchor": "Unexpected stable stoichiometries of sodium chlorides: At ambient pressure, sodium, chlorine, and their only known compound NaCl,\nhave well-understood crystal structures and chemical bonding. Sodium is a\nnearly-free-electron metal with the bcc structure. Chlorine is a molecular\ncrystal, consisting of Cl2 molecules. Sodium chloride, due to the large\nelectronegativity difference between Na and Cl atoms, has highly ionic chemical\nbonding, with stoichiometry 1:1 dictated by charge balance, and rocksalt\n(B1-type) crystal structure in accordance with Pauling's rules. Up to now,\nNa-Cl was thought to be an ultimately simple textbook system. Here, we show\nthat under pressure the stability of compounds in the Na-Cl system changes and\nnew materials with different stoichiometries emerge at pressure as low as 25\nGPa. In addition to NaCl, our theoretical calculations predict the stability of\nNa3Cl, Na2Cl, Na3Cl2, NaCl3 and NaCl7 compounds with unusual bonding and\nelectronic properties. The bandgap is closed for the majority of these\nmaterials. Guided by these predictions, we have synthesized cubic NaCl3 at\n55-60 GPa in the laser-heated diamond anvil cell at temperatures above 2000 K.",
        "positive": "Growth of CuFeO$_2$ Single Crystals by the Optical Floating-Zone\n  Technique: CuFeO$_2$ single crystals up to 50 mm in length and up to 10 mm in diameter\nwere grown by the optical floating-zone method. Stoichiometric polycrystalline\nrods with a diameter of 6-12 mm were used as feed materials to produce crystals\nof sufficient size to be used as substrates for the growth of thin films of\ndelafossites. For stable growth along the $c$-axis, low growth rates of 0.4\nmm/h are necessary. Due to the incongruent melting behavior of CuFeO$_2$, a\nstable melt zone requires adjustment of the lamp power during growth. The\nmelting of CuFeO$_2$ is not simply incongruent because the thermodynamic\nequilibrium includes more than two solid phases and the melt; the gas phase is\nalso involved. The crystals were characterized by X-ray diffraction and X-ray\nfluorescence measurements."
    },
    {
        "anchor": "Computing the band structure and energy gap of penta-graphene by using\n  DFT and G0W0 approximations: In this paper, we consider the optimum coordinate of the penta-graphene.\nPenta-graphene is a new stable carbon allotrope which is stronger than\ngraphene. Here, we compare the band gap of penta-graphene with various density\nfunctional theory (DFT) methods. We plot the band structure of penta-graphene\nwhich calculated with the generalized gradient approximation functional, about\nFermi energy.",
        "positive": "Siloxane crosslinks with dynamic bond exchange enable shape programming\n  in liquid-crystalline elastomers: Liquid crystalline elastomers (LCE) undergo reversible shape changes in\nresponse to stimuli, which may enable a wide range of smart applications, such\nas soft robot, adhesive systems or implantable medical devices. Here we\nintroduce new dynamic covalent chemistry based on siloxane equilibrium exchange\ninto the LCE to enable processing (director alignment, remolding, and welding).\nUnlike, the traditional siloxane-based LCE, which are produced by a other\nreaction schemes with irreversible bonds (e.g. hydrosilylation), here we use a\nmuch more robust reaction (thiol-acrylate/thiol-ene 'double-click' chemistry)\nto obtain highly uniform dynamically crosslinked networks. Combining the\nsiloxane crosslinker with click chemistry produces LCEs with tunable\nproperties, low glass transition (-30C), controllable nematic to isotropic\ntransition (32 to 75C), and a very high vitrification temperature (250C).\nAccordingly, this class of dynamically crosslinked LCE shows unprecedented\nthermal stability within the working temperature range (-50 to 140C), over many\nthermal actuation cycles without any creep. Finally, multiple materials sharing\nthe same siloxane exchangeable bonds can be welded into single structures to\nallow for materials that sequentially and reversibly undergo multiple phase\ntransformations in different sections of the sample."
    },
    {
        "anchor": "Morphotropic Phase Boundaries in Ferromagnets: Tb_{1-x}Dy_xFe_2 Alloys: The structure and properties of the ferromagnet Tb_{1-x}Dy_xFe_2 (Terfenol-D)\nare explored through the morphotropic phase boundary (MPB) separating ferroic\nphases of differing symmetry. Our synchrotron data support a first order\nstructural transition, with a broadening MPB width at higher temperatures. The\noptimal point for magnetomechanical applications is not centered on the MPB but\nlies on the rhombohedral side, where the high striction of the rhombohedral\nmajority phase combines with the softened anisotropy of the MPB. We compare our\nfindings with single ion crystal field theory and with ferroelectric MPBs,\nwhere the controlling energies are different.",
        "positive": "Intrinsic Correlation between Hardness and Elasticity in Polycrystalline\n  Materials and Bulk Metallic Glasses: Though extensively studied, hardness, defined as the resistance of a material\nto deformation, still remains a challenging issue for a formal theoretical\ndescription due to its inherent mechanical complexity. The widely applied\nTeter's empirical correlation between hardness and shear modulus has been\nconsidered to be not always valid for a large variety of materials. Here,\ninspired by the classical work on Pugh's modulus ratio, we develop a\ntheoretical model which establishes a robust correlation between hardness and\nelasticity for a wide class of materials, including bulk metallic glasses, with\nresults in very good agreement with experiment. The simplified form of our\nmodel also provides an unambiguous theoretical evidence for Teter's empirical\ncorrelation."
    },
    {
        "anchor": "Observation of the Breakdown of Optical Phonon Splitting in a\n  Two-dimensional Polar Monolayer: Phonon splitting of the longitudinal optical and transverse optical modes\n(LO-TO splitting), a ubiquitous phenomenon in three-dimensional (3D) polar\nmaterials, is essential for the formation of the 3D phonon polaritons. Theories\npredict that the LO-TO splitting will break down in two-dimensional (2D) polar\nsystems, but direct experimental verification is still missing. Here, using\nmonolayer hexagonal boron nitride (h-BN) as a prototypical example, we report\nthe direct observation of the breakdown of LO-TO splitting and the finite slope\nof the LO phonons at the center of the Brillouin zone in 2D polar materials by\ninelastic electron scattering spectroscopy. Interestingly, the slope of the LO\nphonon in our measurements is lower than the theoretically predicted value for\na freestanding monolayer due to the screening of the Cu foil substrate. This\nenables the phonon polaritons (PhPs) in monolayer h-BN/Cu foil to exhibit\nultra-slow group velocity (~ 5 x 10^-6 c, c is the speed of light) and\nultra-high confinement (~ 4000 times smaller wavelength than that of light).\nOur work reveals the universal law of the LO phonons in 2D polar materials and\nlays a physical foundation for future research on 2D PhPs.",
        "positive": "Rashba splitting of 100 meV in Au-intercalated graphene on SiC: Intercalation of Au can produce giant Rashba-type spin-orbit splittings in\ngraphene but this has not yet been achieved on a semiconductor substrate. For\ngraphene/SiC(0001), Au intercalation yields two phases with different doping.\nHere, we report the preparation of an almost pure p-type graphene phase after\nAu intercalation. We observe a 100 meV Rashba-type spin-orbit splitting at 0.9\neV binding energy. We show that this giant splitting is due to hybridization\nand much more limited in energy and momentum space than for Au-intercalated\ngraphene on Ni."
    },
    {
        "anchor": "The effect of interstitial clusters and vacancies on the STM image of\n  graphite: Making use of the tight-binding Green's function technique, we have\ncalculated the STM images of graphite with surface and sub-surface defects,\nwhile taking into account the relaxation of the lattice due to defects. We have\ndemonstrated that two different physical mechanisms may result in the formation\nof hillocks in the STM images: buckling of the graphite surface due to\ninterstitials between the uppermost graphite layers and the enhancement of the\nelectron density of states close to the Fermi energy on the carbon atoms in the\nvicinity of vacancies. Our results indicate that small hillocks may originate\nboth from the interstitial clusters and from the vacancies. By contrast,\nhowever, large hillocks in excess of 10 \\AA~ in diameter can be caused only by\ninterstitial clusters.",
        "positive": "Ultrafast decoupling of atomic sublattices in a charge-density-wave\n  material: Atomic rearrangements within crystals lie at the foundation of\nelectron-phonon-coupled phenomena such as metal-insulator transition and\nsuperconductivity. Advanced laser-pump-probe studies have recently focused on\nvarious charge-density-wave (CDW) materials to sharpen our understanding of the\ncharge-lattice entanglement, where non-thermal melting of the CDW state is\nevident from the enhanced Bragg diffraction peak intensities - attributed to\nthe dominance of the metal-atom dynamics over the nonmetal-anion one. Here\nusing ultrafast MeV electron diffraction on the prototypical CDW material\n1T-TaSeTe, we observe an unusual coexistence of systematically enhanced and\nsuppressed Bragg peak intensities upon the CDW suppression, indicating a\ndominance of nonmetal-anion dynamics during photoexcitation. By tracking these\natomic trajectories quantitatively through the ultrafast process, we identify a\ntransient state that manifests itself as an unexpected decoupling of the Ta and\nSe/Te sublattices. These findings unambiguously unveil a new kind of laser\nmanipulations of lattice order parameters, which has potentials in creating new\nquantum states and discerning hidden phases such as intra-unit-cell orders."
    },
    {
        "anchor": "The role of stress and diffusion in structure formation in\n  semiconductors: This dissertation addresses two aspects of the theory and simulation of\nstress-diffusion coupling in semiconductors. The first part is a study of the\nrole of kinetics in the formation of pits in stressed thin films. The second\npart describes how atomic-scale calculations can be used to extract the\nthermodynamic and elastic properties of point-defects. For both aspects, there\nexists an interaction between phenomena at the atomic and macroscopic scales\nand the formation of both point-defects and surface features depends on the\nstress state of the system.",
        "positive": "Characterization of Carbon-Contaminated B4C-Coated Optics after\n  Chemically Selective Cleaning with Low-Pressure RF Plasma: Boron carbide (B4C) is one of the few materials that is expected to be mostly\nresilient with respect to the extremely high brilliance of the photon beam\ngenerated by free electron lasers (FELs) and is thus of considerable interest\nfor optical applications in this field. However, as in the case of many other\noptics operated at modern light source facilities, B4C-coated optics are\nsubject to ubiquitous carbon contaminations. These contaminations represent a\nserious issue for the operation of high performance FEL beamlines due to severe\nreduction of photon flux, beam coherence, creation of destructive interference,\nand scattering losses. A variety of B4C cleaning technologies were developed at\ndifferent laboratories with varying success. We present a study regarding the\nlow-pressure RF plasma cleaning of carbon contaminated B4C test samples via\ninductively coupled O2/Ar, H2/Ar, and pure O2 RF plasma produced following\nprevious studies using the same IBSS GV10x downstream plasma source. Results\nregarding the chemistry, morphology as well as other aspects of the B4C optical\ncoating before and after the plasma cleaning are reported. We conclude from\nthese comparative plasma processes that pure O2 feedstock plasma only exhibits\nthe required chemical selectivity for maintaining the integrity of the B4C\noptical coating."
    },
    {
        "anchor": "Silicene Like Domains on IrSi3 Crystallites: Recently, silicene, the graphene equivalent of silicon, has attracted a lot\nof attention due to its compatibility with Si-based electronics. So far,\nsilicene has been epitaxy grown on various crystalline surfaces such as\nAg(110), Ag(111), Ir(111), ZrB2(0001) and Au(110) substrates. Here, we present\na new method to grow silicene via high temperature surface reconstruction of\nhexagonal IrSi3 nanocrystals. The h-IrSi3 nanocrystals are formed by annealing\nthin Ir layers on Si(111) surface. A detailed analysis of the STM images shows\nthe formation of silicene like domains on the surface of some of the IrSi3\ncrystallites. We studied both morphology and electronic properties of these\ndomains by using both scanning tunneling microscopy/spectroscopy and\nfirst-principles calculation methods.",
        "positive": "Two-dimensional natural hyperbolic materials: From polaritons modulation\n  to applications: Natural hyperbolic materials (HMs) in two dimensions (2D) have an\nextraordinarily high anisotropy and a hyperbolic dispersion relation. Some of\nthem can even sustain hyperbolic polaritons with great directional propagation\nand light compression to deeply sub-wavelength scales due to their inherent\nanisotropy. Herein, the anisotropic optical features of 2D natural HMs are\nreviewed. Four hyperbolic polaritons (i.e., phonon polaritons, plasmon\npolaritons, exciton-polaritons, and shear polaritons) as well as their\ngeneration mechanism are discussed in detail. The natural merits of 2D HMs hold\npromise for practical quantum photonic applications such as valley quantum\ninterference, mid-infrared polarizer, spontaneous emission enhancement,\nnear-field thermal radiation, and a new generation of optoelectronic\ncomponents, among others. These analyses' conclusion outlines existing issues\nand potential interesting directions for 2D natural HMs. These findings could\nspur more interest in anisotropic 2D atomic crystals in the future, as well as\nthe quick generation of natural HMs for new applications."
    },
    {
        "anchor": "Accelerating the electronic-structure calculation of magnetic systems by\n  equivariant neural networks: Complex spin-spin interactions in magnets can often lead to magnetic\nsuperlattices with complex local magnetic arrangements, and many of the\nmagnetic superlattices have been found to possess non-trivial topological\nelectronic properties. Due to the huge size and complex magnetic moment\narrangement of the magnetic superlattices, it is a great challenge to perform a\ndirect DFT calculation on them. In this work, an equivariant deep learning\nframework is designed to accelerate the electronic calculation of magnetic\nsystems by exploiting both the equivariant constraints of the magnetic\nHamiltonian matrix and the physical rules of spin-spin interactions. This\nframework can bypass the costly self-consistent iterations and build a direct\nmapping from a magnetic configuration to the ab initio Hamiltonian matrix.\nAfter training on the magnets with random magnetic configurations, our model\nachieved high accuracy on the test structures outside the training set, such as\nspin spiral and non-collinear antiferromagnetic configurations. The trained\nmodel is also used to predict the energy bands of a skyrmion configuration of\nNiBrI containing thousands of atoms, showing the high efficiency of our model\non large magnetic superlattices.",
        "positive": "Heat transport across graphene/hexagonal-BN tilted grain boundaries from\n  phase-field crystal model and molecular dynamics simulations: We study the interfacial thermal conductance of grain boundaries (GBs)\nbetween monolayer graphene and hexagonal boron nitride (h-BN) sheets using a\ncombined atomistic approach. First, realistic samples containing graphene/h-BN\nGBs with different tilt angles are generated using the phase-field crystal\n(PFC) model developed recently [P. Hirvonen \\textit{et al.}, Phys. Rev. B\n\\textbf{100}, 165412 (2019)] that captures slow diffusive relaxation\ninaccessible to molecular dynamics (MD) simulations. Then, large-scale MD\nsimulations using the efficient GPUMD package are performed to assess heat\ntransport and rectification properties across the GBs. We find that lattice\nmismatch between the graphene and h-BN sheets plays a less important role in\ndetermining the interfacial thermal conductance as compared to the tilt angle.\nIn addition, we find no significant thermal rectification effects for these\nGBs."
    },
    {
        "anchor": "Spin-orbit torque for field-free switching in C_{3v} crystals: Spin-orbit torques in noncentrosymmetric polycrystalline magnetic\nheterostructures are usually described in terms of field-like and damping-like\ntorques. However, materials with a lower symmetry point group can exhibit\ntorques whose behavior substantially deviates from the conventional ones. In\nparticular, based on symmetry arguments it was recently proposed that systems\nbelonging to the C_{3v} point group display spin-orbit torques that can promote\nfield-free switching [Liu et al. Nature Nanotechnology 16, 277 (2021)]. In the\npresent work, we analyze the general form of the torques expected in C3v\ncrystals using the Invariant Theory. We uncover several new components that\narise from the coexistence of the three-fold rotation and mirror symmetries.\nUsing both tight binding model and first principles simulations, we show that\nthese unconventional torque components arise from the onset of trigonal warping\nof the Fermi surface and can be as large as the damping-like torque. In other\nwords, the Fermi surface warping is a key indicator to the onset of field-free\nswitching in low symmetry crystals.",
        "positive": "Lattice dynamics and phase transitions in Fe$_{3-x}$GeTe$_2$: We present Raman spectroscopy measurements of the van der Waals bonded\nferromagnet Fe$_{3-x}$GeTe$_2$, together with lattice dynamics. Four out of\neight Raman active modes are observed and assigned, in agreement with numerical\ncalculations. The energies and line-widths of the observed modes display an\nunconventional temperature dependence at about 150 K and 220 K, followed by the\nnonmonotonic evolution of the Raman continuum. Whereas the former can be\nrelated to the magnetic phase transition, the origin of the latter anomaly\nremains an open question."
    },
    {
        "anchor": "Identifying Crystal Structures Beyond Known Prototypes from X-ray Powder\n  Diffraction Spectra: The large amount of powder diffraction data for which the corresponding\ncrystal structures have not yet been identified suggests the existence of\nnumerous undiscovered, physically relevant crystal structure prototypes. In\nthis paper, we present a scheme to resolve powder diffraction data into crystal\nstructures with precise atomic coordinates by screening the space of all\npossible atomic arrangements, i.e., structural prototypes, including those not\npreviously observed, using a pre-trained machine learning (ML) model. This\ninvolves: (i) enumerating all possible symmetry-confined ways in which a given\ncomposition can be accommodated in a given space group, (ii) ranking the\nelement-assigned prototype representations using energies predicted using Wren\nML model [Sci.\\ Adv.\\ 8, eabn4117 (2022)], (iii) assigning and perturbing atoms\nalong the degree of freedom allowed by the Wyckoff positions to match the\nexperimental diffraction data (iv) validating the thermodynamic stability of\nthe material using density-functional theory (DFT). An advantage of the\npresented method is that it does not rely on a database of previously observed\nprototypes and, therefore is capable of finding crystal structures with\nentirely new symmetric arrangements of atoms. We demonstrate the workflow on\nunidentified XRD spectra from the ICDD database and identify a number of stable\nstructures, where a majority turns out to be derivable from known prototypes,\nbut at least two are found to not be part of our prior structural data sets.",
        "positive": "Effects of thermal, elastic, and surface properties on the stability of\n  SiC polytypes: SiC polytypes have been studied for decades, both experimentally and with\natomistic simulations, yet no consensus has been reached on the factors that\ndetermine their stability and growth. Proposed governing factors are\ntemperature-dependent differences in the bulk energy, biaxial strain induced\nthrough point defects, and surface properties. In this work, we investigate the\nthermodynamic stability of the 3C, 2H, 4H, and 6H polytypes with density\nfunctional theory (DFT) calculations. The small differences of the bulk\nenergies between the polytypes can lead to intricate changes in their energetic\nordering depending on the computational method. Therefore, we employ and\ncompare various DFT-codes: VASP, CP2K, and FHI-aims; exchange-correlation\nfunctionals: LDA, PBE, PBEsol, PW91, HSE06, SCAN, and RTPSS; and nine different\nvan der Waals (vdW) corrections. At $T=0$~K, 4H-SiC is marginally more stable\nthan 3C-SiC, and the stability further increases with temperature by including\nentropic effects from lattice vibrations. Neither the most advanced vdW\ncorrections nor strain on the lattice have a significant effect on the relative\npolytype stability. We further investigate the energies of the (0001) polytype\nsurfaces that are commonly exposed during epitaxial growth. For Si-terminated\nsurfaces, we find 3C-SiC to be significantly more stable than 4H-SiC. We\nconclude that the difference in surface energy is likely the driving force for\n3C-nucleation, whereas the difference in the bulk thermodynamic stability\nslightly favors the 4H and 6H polytypes. In order to describe the polytype\nstability during crystal growth correctly, it is thus crucial to take into\naccount both of these effects."
    },
    {
        "anchor": "Creep rupture of materials: insights from a fiber bundle model with\n  relaxation: I adapted a model recently introduced in the context of seismic phenomena, to\nstudy creep rupture of materials. It consists of linear elastic fibers that\ninteract in an equal load sharing scheme, complemented with a local\nviscoelastic relaxation mechanism. The model correctly describes the three\nstages of the creep process, namely an initial Andrade regime of creep\nrelaxation, an intermediate regime of rather constant creep rate, and a\ntertiary regime of accelerated creep towards final failure of the sample. In\nthe tertiary regime creep rate follows the experimentally observed one over\ntime-to-failure dependence. The time of minimum strain rate is systematically\nobserved to be about 60-65 % of the time to failure, in accordance with\nexperimental observations. In addition, burst size statistics of breaking\nevents display a -3/2 power law for events close to the time of failure, and a\nsteeper decay for the all-time distribution. Statistics of interevent times\nshows a tendency of the events to cluster temporarily. This behavior should be\nobservable in acoustic emission experiments.",
        "positive": "A variational approach to nonlinear dynamics of nanoscale surface\n  modulations: In this paper, we propose a variational formulation to study the singular\nevolution equations that govern the dynamics of surface modulations on crystals\nbelow the roughening temperature. The basic idea of the formulation is to\nexpand the surface shape in terms of a complete set of basis functions and to\nuse a variational principle equivalent to the continuum evolution equations to\nobtain coupled nonlinear ordinary differential equations for the expansion\ncoefficients. Unlike several earlier approaches that rely on ad hoc\nregularization procedures to handle the singularities in the evolution\nequations, the only inputs required in the present approach are the orientation\ndependent surface energies and the diffusion constants. The method is applied\nto study the morphological equilibration of patterned unidirectional and\nbidirectional sinusoidal modulations on semiconductor surfaces through surface\ndiffusion."
    },
    {
        "anchor": "Machine Learning and Polymer Self-Consistent Field Theory in Two Spatial\n  Dimensions: A computational framework that leverages data from self-consistent field\ntheory simulations with deep learning to accelerate the exploration of\nparameter space for block copolymers is presented. This is a substantial\ntwo-dimensional extension of the framework introduced in [1]. Several\ninnovations and improvements are proposed. (1) A Sobolev space-trained,\nconvolutional neural network (CNN) is employed to handle the exponential\ndimension increase of the discretized, local average monomer density fields and\nto strongly enforce both spatial translation and rotation invariance of the\npredicted, field-theoretic intensive Hamiltonian. (2) A generative adversarial\nnetwork (GAN) is introduced to efficiently and accurately predict saddle point,\nlocal average monomer density fields without resorting to gradient descent\nmethods that employ the training set. This GAN approach yields important\nsavings of both memory and computational cost. (3) The proposed machine\nlearning framework is successfully applied to 2D cell size optimization as a\nclear illustration of its broad potential to accelerate the exploration of\nparameter space for discovering polymer nanostructures. Extensions to\nthree-dimensional phase discovery appear to be feasible.",
        "positive": "Geometric Control Over the Motion of Magnetic Domain Walls: We propose a method, which enables precise control of magnetic patterns,\nrelying only on the fundamental properties of the wire and the choice of the\npath in the controlled parameter space but not on the rate of motion along this\npath. Possible experimental realizations of this mechanism are discussed. In\nparticular, we show that the domain walls in magnetic nanowires can be\ntranslated by rotation of the magnetic easy axis, or by applying pulses of\nmagnetic field directed transverse to the magnetic easy axis."
    },
    {
        "anchor": "Exploring In$_2$(Se$_{1-x}$Te$_x$)$_3$ alloys as photovoltaic materials: In$_2$Se$_3$ in the three-dimensional (3D) hexagonal crystal structure with\nspace group $P6_1$ ($\\gamma$-In$_2$Se$_3$) has a direct band gap of $\\sim$1.8\neV and high absorption coefficient, making it a promising semiconductor\nmaterial for optoelectronics. Incorporating Te allows for tuning the band gap,\nadding flexibility to device design and extending the application range. Here\nwe report the growth and characterization of $\\gamma$-In$_2$Se$_3$ thin films,\nand results of hybrid density functional theory calculations to assess the\nelectronic and optical properties of $\\gamma$-In$_2$Se$_3$ and\n$\\gamma$-In$_2$(Se$_{1-x}$Te$_x$)$_3$ alloys. The calculated band gap of 1.84\neV for $\\gamma$-In$_2$Se$_3$ is in good agreement with data from the absorption\nspectrum, and the absorption coefficient is found to be as high as that of\ndirect band gap conventional III-V and II-VI semiconductors. Incorporation of\nTe in the form of $\\gamma$-In$_2$(Se$_{1-x}$Te$_x$)$_3$ alloys is an effective\nway to tune the band gap from 1.84 eV down to 1.23 eV, thus covering the\noptimal band gap range for solar cells. We also discuss band gap bowing and\nmixing enthalpies, aiming at adding $\\gamma$-In$_2$Se$_3$ and\n$\\gamma$-In$_2$(Se$_{1-x}$Te$_x$)$_3$ alloys to the available toolbox of\nmaterials for solar cells and other optoelectronic devices.",
        "positive": "The role of the internal demagnetizing field in a surface-modulated\n  magnonic crystal: Magnonic crystals with locally alternating properties and specific\nperiodicities exhibit interesting effects, such as a multitude of different\nspin-wave states and large band gaps. This work aims for demonstrating and\nunderstanding the key role of local demagnetizing fields in such systems. To\nachieve this, hybrid structures are investigated consisting of a continuous\nthin film with a stripe modulation on top favorable due to the adjustability of\nthe magnonic effects with the modulation size. For a direct access to the spin\ndynamics, a magnonic crystal was reconstructed from `bottom-up', i.e., the\nstructural shape as well as the internal field landscape of the structure were\nexperimentally obtained on the nanoscale using electron holography.\nSubsequently, both properties were utilized to perform dynamic response\ncalculations. The simulations yield the frequency-field dependence as well as\nthe angular dependence of spin waves in a magnonic crystal and reveal the\ngoverning role of the internal field landscape around the backward-volume\ngeometry. The complex angle-dependent spin-wave behavior is described for a 360\ndegree in-plane rotation of an external field by connecting the internal field\nlandscape with the individual spin-wave localization."
    },
    {
        "anchor": "The limits of Near Field Immersion Microwave Microscopy evaluated by\n  imaging bilayer graphene Moir\u00e9 patterns: Molecular and atomic imaging required the development of electron and\nscanning probe microscopies to surpass the physical limits dictated by\ndiffraction. Nano-infrared experiments and pico-cavity tip-enhanced Raman\nspectroscopy imaging later demonstrated that radiation in the visible range can\nsurpass this limit by using scanning probe tips to access the near-field\nregime. Here we show that ultimate resolution can be obtained by using scanning\nmicrowave imaging microscopy to reveal structures with feature sizes down to\n1~nm using a radiation of 0.1~m in wavelength. As a test material we use\ntwisted bilayer graphene, which is not only a very important recent topic due\nto the discovery of correlated electron effects such as superconductivity, but\nalso because it provides a sample where we can systematically tune a\nsuperstructure Moir\\'e patterns modulation from below one up to tens of\nnanometers. By analyzing the tip-sample distance dynamics, we demonstrate that\nthis ultimate 10$^8$ probe-to-pattern resolution can be achieved by using\nliquid immersion microscopy concepts and exquisite force control exerted on\nnanoscale water menisci.",
        "positive": "Mesoscopic modeling and experimental validation of thermal and\n  mechanical properties of polypropylene nanocomposites reinforced by\n  graphene-based fillers: The development of nanocomposites relies on structure-property relations,\nwhich necessitate multiscale modeling approaches. This study presents a\nmodelling framework that exploits mesoscopic models to predict the thermal and\nmechanical properties of nanocomposites starting from their molecular\nstructure. In detail, mesoscopic models of polypropylene (PP) and graphene\nbased nanofillers (Graphene (Gr), Graphene Oxide (GO), and reduced Graphene\nOxide (rGO)) are considered. The newly developed mesoscopic model for the PP/Gr\nnanocomposite provides mechanistic information on the thermal and mechanical\nproperties at the filler-matrix interface, which can be then exploited to\nenhance the prediction accuracy of traditional continuum simulations by\ncalibrating the thermal and mechanical properties of the filler-matrix\ninterface. Once validated through a dedicated experimental campaign, this\nmultiscale model demonstrates that with the modest addition of nanofillers (up\nto 2 wt.%), the Young's modulus and thermal conductivity show up to 35% and 25%\nenhancement, respectively, while the Poisson's ratio slightly decreases. Among\nthe different combinations tested, PP/Gr nanocomposite shows the best\nmechanical properties, whereas PP/rGO demonstrates the best thermal\nconductivity. This validated mesoscopic model can contribute to the development\nof smart materials with enhanced mechanical and thermal properties based on\npolypropylene, especially for mechanical, energy storage, and sensing\napplications."
    },
    {
        "anchor": "Towards More Accurate Molecular Dynamics Calculation of Thermal\n  Conductivity. Case Study: GaN Bulk Crystals: Significant differences exist among literature for thermal conductivity of\nvarious systems computed using molecular dynamics simulation. In some cases,\nunphysical results, for example, negative thermal conductivity, have been\nfound. Using GaN as an example case and the direct non-equilibrium method,\nextensive molecular dynamics simulations and Monte Carlo analysis of the\nresults have been carried out to quantify the uncertainty level of the\nmolecular dynamics methods and to identify the conditions that can yield\nsufficiently accurate calculations of thermal conductivity. We found that the\nerrors of the calculations are mainly due to the statistical thermal\nfluctuations. Extrapolating results to the limit of an infinite-size system\ntend to magnify the errors and occasionally lead to unphysical results. The\nerror in bulk estimates can be reduced by performing longer time averages using\nproperly selected systems over a range of sample lengths. If the errors in the\nconductivity estimates associated with each of the sample lengths are kept\nbelow a certain threshold, the likelihood of obtaining unphysical bulk values\nbecomes insignificant. Using a Monte-Carlo approach developed here, we have\ndetermined the probability distributions for the bulk thermal conductivities\nobtained using the direct method. We also have observed a nonlinear effect that\ncan become a source of significant errors. For the extremely accurate results\npresented here, we predict a [0001] GaN thermal conductivity of 185 $\\rm{W/K\n\\cdot m}$ at 300 K, 102 $\\rm{W/K \\cdot m}$ at 500 K, and 74 $\\rm{W/K \\cdot m}$\nat 800 K. Using the insights obtained in the work, we have achieved a\ncorresponding error level (standard deviation) for the bulk (infinite sample\nlength) GaN thermal conductivity of less than 10 $\\rm{W/K \\cdot m}$, 5 $\\rm{W/K\n\\cdot m}$, and 15 $\\rm{W/K \\cdot m}$ at 300 K, 500 K, and 800 K respectively.",
        "positive": "InGaAs/GaAs/alkanethiolate radial superlattices: Experimental: A radial InGaAs/GaAs/1-hexadecanethiol superlattice is fabricated by the\nroll-up of a strained InGaAs/GaAs bilayer passivated with a molecular\nself-assembled monolayer. Our technique allows the formation of multi-period\ninorganic/organic hybrid heterostructures. This paper contains the detailed\nexperimental description of how to fabricate these structures."
    },
    {
        "anchor": "On how good DFT exchange-correlation functionals are for H bonds in\n  small water clusters: Benchmarks approaching the complete basis set limit: The ability of several density-functional theory (DFT) exchange-correlation\nfunctionals to describe hydrogen bonds in small water clusters (dimer to\npentamer) in their global minimum energy structures is evaluated with reference\nto second order Moeller Plesset perturbation theory (MP2). Errors from basis\nset incompleteness have been minimized in both the MP2 reference data and the\nDFT calculations, thus enabling a consistent systematic evaluation of the true\nperformance of the tested functionals. Among all the functionals considered,\nthe hybrid X3LYP and PBE0 functionals offer the best performance and among the\nnon-hybrid GGA functionals mPWLYP and PBE1W perform the best. The popular BLYP\nand B3LYP functionals consistently underbind and PBE and PW91 display rather\nvariable performance with cluster size.",
        "positive": "On the origin of extremely high strength of ultrafine-grained Al alloys\n  produced by severe plastic deformation: Ultrafine-grained Al alloys produced by high pressure torsion are found to\nexhibit a very high strength, considerably exceeding the Hall-Petch predictions\nfor the ultrafine grains. The phenomena can be attributed to the unique\ncombination of ultrafine structure and deformation-induced segregations of\nsolute elements along grain boundaries, which may affect the emission and\nmobility of intragranular dislocations."
    },
    {
        "anchor": "A new class of organic molecular magnets: Using detailed first principles calculations, we have found a new class of\nstable organic molecular magnets based on zwitterionic molecules possessing\ndonor, $\\pi$ bridge, and acceptor groups. These molecules are organic molecules\ncontaining only C, H and N. The quantum mechanical nature of the magnetic\nproperties originates from the conjugated $\\pi$ bridge (involving only p\nelectrons) where the exchange interactions between electron spin are relatively\nstrong and local and are independent of the length of the $\\pi$ bridge,\nenabling the easy construction of a molecular magnetic device with specified\nlength.",
        "positive": "Computer Simulations of Friction, Lubrication and Wear: An overview of computer simulations of tribology is presented. The chapter\nbegins with a brief overview of simulation techniques and the special\nrequirements for simulations of tribological processes. Then simple\none-dimensional models of friction between crystalline surfaces are introduced\nto illustrate general features of friction, such as the importance of\nmetastability and the effect of commensurability. Next two- and\nthree-dimensional studies of dry sliding between crystalline surfaces are\ndescribed, and compared to scanning probe experiments and measurements of the\nfriction on adsorbed monolayers. Lubrication is then discussed, starting from\nthick films and describing the breakdown in bulk hydrodynamics as the thickness\nof the lubricant decreases to molecular scales. Deviations from the usual\nno-slip boundary condition are quantified and the onset of solid behavior in\nmolecularly thick films is described. The possibility that solidification of\nthin layers of adventitious carbon is responsible for the prevalence of static\nfriction is explored. The final sections describe stick-slip motion,\ntribochemical reactions, machining, and the evolution of microstructure in\nsliding contacts."
    },
    {
        "anchor": "Simulating high-pressure surface reactions with molecular beams: Using a reactive molecular beam with high kinetic energy ($E_{kin}$) it is\npossible to speed gas-surface reactions involving high activation barriers\n($E_{act}$), which would require elevated pressures ($P_0$) if a random gas\nwith a Maxwell-Boltzmann distribution is used. By simply computing the number\nof molecules that overcome the activation barrier in a random gas at $P_0$ and\nin a molecular beam at $E_{kin}$=$E_{act}$, we establish an $E_{kin}$-$P_0$\nequivalence curve, through which we postulate that molecular beams are ideal\ntools to investigate gas-surface reactions that involve high activation\nenergies. In particular, we foresee the use of molecular beams to simulate gas\nsurface reactions within the industrial-range ($>$ 10 bar) using\nsurface-sensitive Ultra-High Vacuum (UHV) techniques, such as X-ray\nphotoemission spectroscopy (XPS). To test this idea, we revisit the oxidation\nof the Cu(111) surface combining O$_2$ molecular beams and XPS experiments. By\ntuning the kinetic energy of the O$_2$ beam in the range 0.24-1 eV we achieve\nthe same sequence of surface oxides obtained in Ambient Pressure Photoemission\n(AP-XPS) experiments, in which the Cu(111) surface was exposed to a random\nO$_2$ gas up to 1 mbar. We observe the same surface oxidation kinetics as in\nthe random gas, but with a much lower dose, close to the expected value derived\nfrom the equivalence curve.",
        "positive": "Symmetry and polarity of antiphase boundaries in PbZrO$_3$: The polar properties of antiphase boundaries (APBs) in PbZrO$_3$ are analyzed\nin detail using a recently developed layer group approach in order parameter\nspace and compared with the results from Landau-Ginzburg free energy\ndescription. It is shown that the former approach reveals the microscopic APBs'\nproperties, and predicts polar APB structures at particular positions inside\nthe unit cell, which agree very well with recent experimental obsevations [Wei,\net.~al. \\cite{Wei2014,Wei2015}]. The systematic usage of the method is\ndeveloped. In contrast with it the commonly used free energy description\nobscures the microscopic features but still can reflect the macroscopic\nproperties of the APBs by taking into account the bilinear coupling of\npolarization and order parameter gradients. The relation between the layer\ngroup approach and the Landau-Ginzburg free energy description is discussed and\ntwo mechanisms of polarization switching inside the APBs are distinguished. It\nis illustrated that the polar APBs observed in PbZrO$_3$ are consistently and\nnaturally explained by the layer group approach. This analysis is expected to\nhave a significant impact also in other materials."
    },
    {
        "anchor": "Theory of unconventional Smith-Purcell radiation in finite-size photonic\n  crystals: Unusual emission of light, called the unconventional Smith-Purcell radiation\n(uSPR) in this paper, was demonstrated from an electron traveling near a finite\nphotonic crystal (PhC) at an ultra-relativistic velocity. This phenomenon is\nnot related to the accepted mechanism of the conventional SPR and arises\nbecause the evanescent light from the electron has such a small decay constant\nin the ultra-relativistic regime that it works practically as a plane-wave\nprobe entering the PhC from one end. We analyze the dependence of the SPR\nspectrum on the velocity of electron and on the parity of excited photonic\nbands and show, for PhCs made up of a finite number of cylinders, that uSPR\nprobes the photonic band structure very faithfully.",
        "positive": "Trapping of He Clusters by Inert-Gas Impurities in Tungsten:\n  First-Principles Predictions and Experimental Validation: Properties of point defects resulting from the incorporation of inert-gas\natoms in bcc tungsten are investigated systematically using first-principles\ndensity functional theory (DFT) calculations. The most stable configuration for\nthe interstitial neon, argon, krypton and xenon atoms is the tetrahedral site,\nsimilarly to what was found earlier for helium in W. The calculated formation\nenergies for single inert-gas atoms at interstitial sites as well as at\nsubstitutional sites are much larger for Ne, Ar, Kr and Xe than for He. While\nthe variation of the energy of insertion of inert-gas defects into interstitial\nconfigurations can be explained by a strong effect of their large atomic size,\nthe trend exhibited by their substitutional energies is more likely related to\nthe covalent interaction between the noble gas impurity atoms and the tungsten\natoms. There is a remarkable variation exhibited by the energy of interaction\nbetween inert-gas impurities and vacancies, where a pronounced size effect is\nobserved when going from He to Ne, Ar, Kr, Xe. The origin of this trend is\nexplained by electronic structure calculations showing that p-orbitals play an\nimportant part in the formation of chemical bonds between a vacancy and an atom\nof any of the four inert-gas elements in comparison with helium, where the\nlatter contains only 1s2 electrons in the outer shell. The binding energies of\na helium atom trapped by five different defects (He-v, Ne-v, Ar-v, Kr-v, Xe-v,\nwhere v denotes a vacancy in bcc-W) are all in excellent agreement with\nexperimental data derived from thermal desorption spectroscopy. Attachment of\nHe clusters to inert gas impurity atom traps in tungsten is analysed as a\nfunction of the number of successive trapping helium atoms. Variation of the\nYoung modulus due to inert-gas impurities is analysed on the basis of data\nderived from DFT calculations."
    },
    {
        "anchor": "Aging of the surface of Bi(2)Se(3): We study the electronic structure of Bi(2)Se(3) employing high resolution\nphotoemission spectroscopy and discover the dependence of the behavior of Dirac\nparticles on surface terminations. The Dirac cone apex appears at different\nenergies and exhibits contrasting shift on Bi and Se terminated surface with\ncomplex time dependence emerging from subtle adsorbed oxygen-surface atom\ninteractions. These results uncover the surface states behavior of real systems\npossessing topologically ordered surface.",
        "positive": "Half-metallic ferromagnetism and Ru-induced localization in quaternary\n  Heusler alloy CoRuMnSi: We report a combined theoretical and experimental investigation of\nhalf-metallic ferromagnetism in equiatomic quaternary Heusler alloy CoRuMnSi.\nRoom temperature XRD analysis reveals that the alloy crystallizes in L21\ndisorder instead of pristine Y-type structure due to 50% swap disorder between\nthe tetrahedral sites, i.e., Co and Ru atoms. Magnetization measurements reveal\na net magnetization of 4 $\\mu_B$ with Curie temperature of ~780 K. Resistivity\nmeasurement reveals the presence of localization effect below 35 K while above\n100 K, a linear dependence is observed. Resistivity behavior indicates the\nabsence of single magnon scattering, which indirectly supports the\nhalf-metallic nature. The majority spin band near the Fermi level clearly\nindicates the overlap of flat eg bands with sharply varying conduction bands\nthat are responsible for the localization. In-depth analysis of the projected\natomic d-orbital character of band structure reveals unusual bonding, giving\nrise to the flat eg bands purely arising out of Ru ions. Co-Ru swap disorder\ncalculations indicate the robustness of half-metallic nature, even when the\nstructure changes from Y-type to L21-type, with no major change in the net\nmagnetization of the system. Thus, robust half-metallic nature, stable\nstructure, and high Curie temperature make this alloy quite a promising\ncandidate to be used as a source of highly spin-polarized currents in\nspintronic applications."
    },
    {
        "anchor": "Carbon Kagome Nanotubes -- quasi-one-dimensional nanostructures with\n  flat bands: We introduce carbon Kagome nanotubes (CKNTs) -- a new allotrope of carbon\nformed by rolling up sheets of Kagome graphene, and investigate the properties\nof this material using first principles calculations. Based on the direction of\nrolling, we identify two principal varieties of CKNTs -- armchair and zigzag,\nand find that the bending stiffness associated with rolling Kagome graphene\ninto either type of CKNT is about a third of that associated with rolling\nconventional graphene into carbon nanotubes (CNTs). Ab initio molecular\ndynamics simulations indicate that both types of CKNTs are likely to exist as\nstable structures at room temperature. Each CKNT explored here is metallic and\nfeatures dispersionless states (i.e., flat bands) throughout its Brillouin\nzone, along with an associated singular peak in the electronic density of\nstates, close to the Fermi level. We calculate the mechanical and electronic\nresponse of CKNTs to torsional and axial strains and compare against\nconventional CNTs. We show in particular, that upon twisting, degenerate\ndispersionless electronic states in CKNTs split, Dirac points and partially\nflat bands emerge from the quadratic band crossing point at the Fermi level,\nand that these features can be explained using a relatively simple\ntight-binding model.\n  Overall, CKNTs appear to be unique and striking examples of realistic\nelemental quasi-one-dimensional (1D) materials that can potentially display\nfascinating collective material properties arising from the presence of\nstrongly correlated electrons. Additionally, distorted CKNTs may provide an\ninteresting material platform where flat band physics and chirality induced\nanomalous transport effects may be studied together.",
        "positive": "Spin Seebeck effect in $\\varepsilon$-Fe$_2$O$_3$ thin layer with high\n  coercive field: Spin Seebeck effect has been investigated in Pt/$\\varepsilon$-Fe$_2$O$_3$\nbilayers. The $\\varepsilon$-Fe$_2$O$_3$ thin layer with $40-70$~nm thickness\nwere deposited by a spin-coating method on Y:ZrO$_2$(100) substrates. The\nprepared layers are highly oriented with the easy magnetic $a$-axis parallel to\nthe film surface. The magnetic hysteresis loops measured at room temperature\nwith magnetic field parallel to the layer exhibit coercive fields up to\n11.6~kOe, which is so far the highest value measured for\n$\\varepsilon$-Fe$_2$O$_3$ thin layer samples. The shape of the spin Seebeck\nhysteresis loops is similar to the shape of magnetization for single phase\nlayers with coercive field around 10~kOe. In some prepared layers a small\namount of secondary soft ferrimagnetic phase is revealed by a constricted shape\nof magnetization loops, in contrast to spin Seebeck loops, where no\nconstriction is observed. A difference in encountered in the case of layers\nwith a small amount ($1-2$~volume\\%) of secondary soft ferrimagnetic phase,\nwhich is revealed by a constricted shape of magnetization loops, in contrast to\nspin Seebeck loops, where no constriction is observed."
    },
    {
        "anchor": "Extremely large magnetoresistance in a topological semimetal candidate\n  pyrite PtBi2: While pyrite-type PtBi2 with face-centered cubic structure has been predicted\nto be a three-dimensional (3D) Dirac semimetal, experimental study on its\nphysical properties remains absent. Here we report the angular-dependent\nmagnetoresistance (MR) measurements of PtBi2 single-crystal under high magnetic\nfields. We observed extreme large unsaturated magnetoresistance (XMR) up to\n11.2 million percent at T = 1.8 K in a magnetic field of 33 T, which surpasses\nthe previously reported Dirac materials, such as WTe2, LaSb and NbP. The\ncrystals exhibit an ultrahigh mobility and significant Shubnikov-de Hass (SdH)\nquantum oscillations with nontrivial Berry's phase. Analysis of Hall\nresistivity indicates that the XMR can be ascribed to the nearly compensated\nelectron and hole. Our experimental results associated with the ab initio\ncalculations suggest that pyrite PtBi2 is a topological semimetal candidate\nwhich might provide a platform for exploring topological materials with XMR in\nnoble metal alloys.",
        "positive": "Evolution of Structure and Magnetic Properties of Cu2MnBO5 under Partial\n  Mn3+->Fe3+ Substitution: Single crystals of Fe-substituted Cu2Mn1-xFexBO5 ludwigites have been\nsynthesized using flux technique (x=0.2, 0.4, 0.5 - in the initial flux\nsystem). Structural properties of the synthesized compounds were studied by the\nsingle crystal and powder X-ray diffraction analysis. Obtained results were\nanalyzed in the relationship with parent compound Cu2MnBO5. It was revealed\nthat the type of monoclinic distortions of Fe-substituted ludwigites is\ndifferent from the structure of Cu2MnBO5. The real cation composition and local\nstructure of Cu2Mn1-xFexBO5 ludwigites were studied using XANES and EXAFS\ntechniques, respectively. Analysis of field and thermal dependencies of\nmagnetization showed a strong dependence of the magnetic properties of these\nludwigites on x with changing the type of magnetic ordering."
    },
    {
        "anchor": "Optical phonon dynamics and electronic fluctuations in the Dirac\n  semimetal Cd3As2: Raman scattering in the three-dimensional Dirac semimetal Cd3As2 shows an\nintricate interplay of electronic and phonon degrees of freedom. We observe\nresonant phonon scattering due to interband transitions, an anomalous\nanharmonicity of phonon frequency and intensity, as well as quasielastic (E~0)\nelectronic scattering. The latter two effects are governed by a characteristic\ntemperature scale T* ~ 100 K that is related to mutual fluctuations of lattice\nand electronic degrees of freedom. A refined analysis shows that this\ncharacteristic temperature corresponds to the energy of optical phonons which\ncouple to interband transitions in the Dirac states of Cd3As2. As\nelectron-phonon coupling in a topological semimetal is primarily related to\nphonons with finite momenta, the back action on the optical phonons in only\nobserved as anharmonicities via multi-phonon processes involving a broad range\nof momenta. The resulting energy density fluctuations of the coupled system\nhave previously only been observed in low dimensional or frustrated spin\nsystems with suppressed long range ordering.",
        "positive": "Voltage-controlled coded qubit based on electron spin: We design and analyze a solid state qubit based on electron spin and\ncontrolled by electrical means. The coded qubit is composed of a three-electron\ncomplex in three tunable gated quantum dots. The two logical states of a qubit,\n|0L> and |1L>, reside in a degenerate subspace of total spin S=1/2 states. We\ndemonstrate how applying voltages to specific gates changes the one-electron\nproperties of the structure, and show how electron-electron interaction\ntranslates these changes into the manipulation of the two lowest energy states\nof the three-electron complex."
    },
    {
        "anchor": "A Novel Pyrochlore Ruthenate: Ca2Ru2O7: Single crystals of a novel ruthenate, Ca2Ru2O7, were obtained. An X-ray\ndiffraction study on a single crystal revealed that this material crystallizes\nin a pyrochlore structure with a lattice parameter, a = 10.197 Angstroms. The\nmagnetic susceptibility above 30 K is the summation of a Curie-Weiss\ncontribution and a constant term independent of temperature. The effective\nmoment per Ru atom is only 0.36 Bohr magnetons, one order of magnitude smaller\nthan that expected from a localized spin model with S=3/2 for Ru5+. Below 23 K,\nthe localized spins freeze in a spin-glass state. The resistivity at room\ntemperature is 2E-3 Ohm cm, comparable to that in metallic, highly correlated\noxides.}",
        "positive": "Magnetically-Sensitive Valley Polarization Reversal and Revival of\n  Defect-Localized Excitons in WSe2-WS2: Manipulating and reserving the valley pseudospin of excitons is one core aim\nin the two-dimensional transition metal dichalcogenides (TMDs). However, due to\nthe strong electron-hole exchange and spin-orbit coupling interactions, the\nexciton recombination lifetime is subject to picosecond timescale\nintrinsically, and the valley polarization is hardly modulated by a moderate\nmagnetic field. It is fortunate that interlayer and defect-localized excitons\npromise to overcome these difficulties by suppressing the above interactions.\nHere we clearly reveal that the valley polarization can be reversed and revived\nin the defect-localized excitons with a microsecond lifetime in AB-stacked\nWSe2-WS2 heterobilayer. Specifically, for the interlayer defect-localized\nexciton, the valley polarization is reversed and can be efficiently enhanced by\na weak out-of-plane magnetic field (<0.4 T). In sharp contrast, the valley\npolarization of the intralayer defect-localized exciton can revive after a fast\ndecay process and follows the direction of the moderate out-of-plane magnetic\nfield (<3 T). We explain the reversed valley polarization with highly magnetic\nsensitivity by the delocalization of defect-localized holes under a weak\nmagnetic field and the revival of valley polarization by the valley Zeeman\neffect under a moderate magnetic field. Our results demonstrate that the valley\npseudospin of defect-localized excitons can be efficiently modulated by the\nexternal magnetic field and enrich both the understanding and the technical\napproaches on manipulating the valley dynamics in TMDs and their\nheterostructure."
    },
    {
        "anchor": "Frequency shift keying in vortex-based spin torque oscillators: Vortex-based spin-torque oscillators can be made from extended spin valves\nconnected to an electrical nanocontact. We study the implementation of\nfrequency shift keying modulation in these oscillators. Upon a square\nmodulation of the current in the 10 MHz range, the vortex frequency follows the\ncurrent command, with easy identification of the two swapping frequencies in\nthe spectral measurements. The frequency distribution of the output power can\nbe accounted for by convolution transformations of the dc current vortex\nwaveform, and the current modulation. Modeling indicates that the frequency\ntransitions are phase coherent and last less than 25 ns. Complementing the\nmulti-octave tunability and first-class agility, the capability of frequency\nshift keying modulation is an additional milestone for the implementation of\nvortex-based oscillators in RF circuit.",
        "positive": "Crystal lattice rules disordered states: Based on classical statistical thermodynamics, we develop a theoretical\napproach that provides new insight into how macroscopic and microscopic\nphysical properties are bridged via crystal lattice for condensed mat- ters. We\nfind that in order to determine macroscopic physical properties and their\ntemperature dependence in equilibrium disordered state, information about a few\nspecially selected microscopic states, established from geometrical\ncharacteristics of the crystal lattice, is sufficient. These special states are\nfound to be independent of constitument elements as well as of temperature,\nwhich is in contrast to the standard conception in statistical thermodyanamics\nwhere a set of microscopic states mainly contributing to determining\nmacroscopic physical properties depend on temperature and constituent elements.\nValidity and applicability of the theoretical ap- proach is confirmed through\nprediction of macroscopic physical properties in practical alloys, compared\nwith prediction by full thermodynamic simulation. The present findings provide\nefficient and systematic prediction of macroscopic physical properties for\nequilibrium disordered states based on those for special microscopic states\nwithout any information of interactions for given system."
    },
    {
        "anchor": "Origin of the Ising Ferrimagnetism and Spin-Charge Coupling in LuFe2O4: The spin ordering and spin-charge coupling in LuFe2O4 were investigated on\nthe basis of density functional calculations and Monte Carlo simulations. The\n2:1 ferrimagnetism arises from the strong antiferromagnetic intra-sheet\nFe3+-Fe3+ and Fe3+ -Fe2+ as well as some substantial antiferromagnetic\nFe2+-Fe3+ inter-sheet spin exchange interactions. The giant magnetocapacitance\nat room temperature and the enhanced electric polarization at 240 K of LuFe2O4\nare explained by the strong spin-charge coupling.",
        "positive": "A new diluted magnetic semiconductor: The half-metallic ferromagnet\n  CoTi(1-x)FexSb: Half-Heusler compounds with 18 valence electrons are semi-conducting. It will\nbe shown that doping with electrons results in half-metallic ferromagnets,\nsimilar to the case of diluted semi-conductors. CoTiSb is known to be a\nsemi-conducting Half-Heusler compound. Doping by Fe is expected to result in\nferromagnetic order. It was found that Ti can be replaced by up to about 10% Fe\nwhile its crystal structure still remains C1b, which was proved by X-ray powder\ndiffraction. SQUID magnetometry revealed a magnetic moment of 0.32 mB per unit\ncell at 5K."
    },
    {
        "anchor": "Tunable bandgaps and excitons in doped semiconducting carbon nanotubes\n  made possible by acoustic plasmons: Doping of semiconductors is essential in modern electronic and photonic\ndevices. While doping is well understood in bulk semiconductors, the advent of\ncarbon nanotubes and nanowires for nanoelectronic and nanophotonic applications\nraises some key questions about the role and impact of doping at low\ndimensionality. Here we show that for semiconducting carbon nanotubes, bandgaps\nand exciton binding energies can be dramatically reduced upon experimentally\nrelevant doping, and can be tuned gradually over a broad range of energies in\ncontrast to higher dimensional systems. The later feature is made possible by a\nnovel mechanism involving strong dynamical screening effects mediated by\nacoustic plasmons.",
        "positive": "Chemical vapor deposition growth of bilayer graphene in between\n  molybdenum disulfide sheets: Direct growth of flat micrometer-sized bilayer graphene islands in between\nmolybdenum disulfide sheets is achieved by chemical vapor deposition of\nethylene at about 800 {\\deg}C. The temperature assisted decomposition of\nethylene takes place mainly at molybdenum disulfide step edges. The carbon\natoms intercalate at this high temperature, and during the deposition process,\nthrough defects of the molybdenum disulfide surface such as steps and wrinkles.\nPost growth atomic force microscopy images reveal that circular flat graphene\nislands have grown at a high yield. They consist of two graphene layers stacked\non top of each other with a total thickness of 0.74 nm. Our results demonstrate\ndirect, simple and high yield growth of graphene/molybdenum disulfide\nheterostructures, which can be of high importance in future nanoelectronic and\noptoelectronic applications."
    },
    {
        "anchor": "Dispersive photoluminescence decay by geminate recombination in\n  amorphous semiconductors: The photoluminescence decay in amorphous semiconductors is described by power\nlaw $t^{-delta}$ at long times. The power-law decay of photoluminescence at\nlong times is commonly observed but recent experiments have revealed that the\nexponent, $delta sim 1.2-1.3$, is smaller than the value 1.5 predicted from a\ngeminate recombination model assuming normal diffusion. Transient currents\nobserved in the time-of-flight experiments are highly dispersive characterized\nby the disorder parameter $alpha$ smaller than 1. Geminate recombination rate\nshould be influenced by the dispersive transport of charge carriers. In this\npaper we derive the simple relation, $delta = 1+ alpha/2 $. Not only the\nexponent but also the amplitude of the decay calculated in this study is\nconsistent with measured photoluminescence in a-Si:H.",
        "positive": "Influence of Interface Geometry on Phase Stability and Bandgap\n  Engineering in Boron Nitride substituted Graphene: A Combined\n  First-principles and Monte Carlo Study: Using combination of Density Functional Theory and Monte Carlo simulation, we\nstudy the phase stability and electronic properties of two dimensional\nhexagonal composites of boron nitride and graphene, with a goal to uncover the\nrole of the interface geometry formed between the two. Our study highlights\nthat preferential creation of extended armchair interfaces may facilitate\nformation of solid solution of boron nitride and graphene within a certain\ntemperature range. We further find that for band-gap engineering, armchair\ninterfaces or patchy interfaces with mixed geometry are most suitable.\nExtending the study to nanoribbon geometry shows that reduction of\ndimensionality makes the tendency to phase segregation of the two phases even\nstronger. Our thorough study should form an useful database in designing boron\nnitride-graphene composites with desired properties."
    },
    {
        "anchor": "Broadband Ferromagnetic Resonance Linewidth Measurement of Magnetic\n  Tunnel Junction Multilayers: The broadband ferromagnetic resonance (FMR) linewidth of the free layer of\nmagnetic tunnel junctions is used as a simple diagnostic of the quality of the\nmagnetic structure. The FMR linewidth increases near the field regions of free\nlayer reversal and pinned layer reversal, and this increase correlates with an\nincrease in magnetic hysteresis in unpatterned films, low frequency noise in\npatterned devices, and previous observations of magnetic domain ripple by use\nof Lorentz microscopy. Postannealing changes the free layer FMR linewidth\nindicating that considerable magnetic disorder, originating in the\nexchange-biased pinned layer, is transferred to the free layer.",
        "positive": "Thermal transport at a nanoparticle-water interface: A molecular\n  dynamics and continuum modeling study: Heat transfer between a silver nanoparticle and surrounding water has been\nstudied using molecular dynamics (MD) simulations. The thermal conductance\n(Kapitza conductance) at the interface between a nanoparticle and surrounding\nwater has been calculated using four different approaches: transient\nwith/without temperature gradient (internal thermal resistance) in the\nnanoparticle, steady-state non-equilibrium and finally equilibrium simulations.\nThe results of steady-state non-equilibrium and equilibrium are in agreement\nbut differ from the transient approach results. MD simulations results also\nreveal that in the quenching process of a hot silver nanoparticle, heat\ndissipates into the solvent over a length-scale of ~ 2nm and over a timescale\nof less than 5ps. By introducing a continuum solid-like model and considering a\nheat conduction mechanism in water, it is observed that the results of the\ntemperature distribution for water shells around the nanoparticle agree well\nwith MD results. It is also found that the local water thermal conductivity\naround the nanoparticle is greater by about 50 percent than that of bulk water.\nThese results have important implications for understanding heat transfer\nmechanisms in nanofluids systems and also for cancer photothermal therapy,\nwherein an accurate local description of heat transfer in an aqueous\nenvironment is crucial."
    },
    {
        "anchor": "Anionic Character of the Conduction Band of Sodium Chloride: The alkali halides are ionic compounds. Each alkali atom donates an electron\nto a halogen atom, leading to ions with full shells. The valence band is mainly\nlocated on halogen atoms, while, in a traditional picture, the conduction band\nis mainly located on alkali atoms. Scanning tunnelling microscopy of NaCl at 4\nK actually shows that the conduction band is located on Cl$^-$ because the\nstrong Madelung potential reverses the order of the Na$^+$ 3s and Cl$^-$ 4s\nlevels. We verify this reversal is true for both atomically thin and bulk NaCl,\nand discuss implications for II-VI and I-VII compounds.",
        "positive": "Stochastic processes in magnetization reversal involving domain wall\n  motion in magnetic memory elements: We show experimentally through time-resolved conductance measurements that\nmagnetization reversal through domain wall motion in sub-100 nm diameter\nmagnetic tunnel junctions is dominated by two distinct stochastic effects. The\nfirst involves the incubation time related to domain wall nucleation, while the\nsecond results from stochastic motion in the Walker regime. Micromagnetics\nsimulations reveal several contributions to temporal pinning of the wall near\nthe disk center, including Bloch point nucleation and wall precession. We show\nthat a reproducible ballistic motion is recovered when Bloch and N\\'eel wall\nprofiles become degenerate in energy in optimally sized disks, which enables\nquasi-deterministic motion."
    },
    {
        "anchor": "Manipulating the fully spin-polarized edge currents in graphene ribbon: Electron fully spin-polarized edge states in graphene emerged at the\ninterfaces of a nonuniform magnetic field are studied numerically in a\ntight-binding model, with both the orbital and Zeeman-splitting effects of\nmagnetic field considered. We show that the fully spin-polarized currents can\nbe manipulated by a gate voltage. In order to make use of the fully\nspin-polarized currents in the spin related transport, a three-terminal\nexperiment is designed and expected to export the fully spin-polarized\ncurrents. This may have important applications in spin based nanodevices.",
        "positive": "Modeling of Isotropic Backward-Wave Materials Composed of Resonant\n  Spheres: A possibility to realize isotropic artificial backward-wave materials is\ntheoretically analyzed. An improved mixing rule for the effective permittivity\nof a composite material consisting of two sets of resonant dielectric spheres\nin a homogeneous background is presented. The equations are validated using the\nMie theory and numerical simulations. The effect of a statistical distribution\nof sphere sizes on the increasing of losses in the operating frequency band is\ndiscussed and some examples are shown."
    },
    {
        "anchor": "Probing anharmonic phonons by quantum correlators: A path integral\n  approach: We devise an efficient scheme to determine vibrational properties from Path\nIntegral Molecular Dynamics (PIMD) simulations. The method is based on\nzero-time Kubo-transformed correlation functions and captures the anharmonicity\nof the potential due to both temperature and quantum effects. Using analytical\nderivations and numerical calculations on toy-model potentials, we show that\ntwo different estimators built upon PIMD correlation functions fully\ncharacterize the phonon spectra and the anharmonicity strength. The first\nestimator is associated with force-force quantum correlators and gives access\nto the fundamental frequencies and thermodynamic properties of the quantum\nsystem. The second one is instead connected to displacement-displacement\ncorrelators and probes the lowest-energy phonon excitations with high accuracy.\nWe also prove that the use of generalized eigenvalue equations, in place of the\nstandard normal mode equations, leads to a significant speed-up in the PIMD\nphonon calculations, both in terms of faster convergence rate and smaller\ntime-step bias. Within this framework, using ab initio PIMD simulations, we\ncompute phonon dispersions of diamond and of the high-pressure I41/amd phase of\natomic hydrogen. We find that, in the latter case, the anharmonicity is\nstronger than previously estimated and yields a sizeable red-shift in the\nvibrational spectrum of atomic hydrogen.",
        "positive": "Elliott-Yafet Spin-Phonon Relaxation Times from First Principles: We present a first-principles approach for computing the phonon-limited $T_1$\nspin relaxation time due to the Elliot-Yafet mechanism. Our scheme combines\nfully-relativistic spin-flip electron-phonon interactions with an approach to\ncompute the effective spin of band electrons in materials with inversion\nsymmetry. We apply our method to silicon and diamond, for which we compute the\ntemperature dependence of the spin relaxation times and analyze the\ncontributions to spin relaxation from different phonons and valley processes.\nThe computed spin relaxation times in silicon are in excellent agreement with\nexperiment in the 50$-$300 K temperature range. In diamond, we predict\nintrinsic spin relaxation times of 540 $\\mu$s at 77 K and 2.3 $\\mu$s at 300 K.\nOur work enables precise predictions of spin-phonon relaxation times in a wide\nrange of materials, providing microscopic insight into spin relaxation and\nguiding the development of spin-based quantum technologies."
    },
    {
        "anchor": "Parametric dependence of hot electron relaxation timescales on\n  electron-electron and electron-phonon interaction strengths: Understanding how photoexcited electron dynamics depend on electron-electron\n(e-e) and electron-phonon (e-p) interaction strengths is important for many\nfields, e.g. ultrafast magnetism, photocatalysis, plasmonics, and others. Here,\nwe report simple expressions that capture the interplay of e-e and e-p\ninteractions on electron distribution relaxation times. We observe a dependence\nof the dynamics on e-e and e-p interaction strengths that is universal to most\nmetals and is also counterintuitive. While only e-p interactions reduce the\ntotal energy stored by excited electrons, the time for energy to leave the\nelectronic subsystem also depends on e-e interaction strengths because e-e\ninteractions increase the number of electrons emitting phonons. The effect of\ne-e interactions on energy-relaxation is largest in metals with strong e-p\ninteractions. Finally, the time high energy electron states remain occupied\ndepends only on the strength of e-e interactions, even if e-p scattering rates\nare much greater than e-e scattering rates.",
        "positive": "Background Proportional Enhancement of the Extended Fine Structure in\n  Nonresonant Inelastic X-ray Scattering: We report new measurements and calculations of the non-resonant inelastic\nx-ray scattering (NRIXS) from Mg and Al for a wide range of momentum transfers,\nq. Extended oscillations in the dynamic structure factor S(q,w) due to\nscattering from the 2p and 2s orbitals (i.e. L-edges) are observed out to more\nthan 150 eV past the binding energy. These results are discussed in context of\nthe recently proposed representation of S(q,w) for core shells as an atomic\nbackground modulated by interference between different photoelectron scattering\npaths, in analogy to the standard treatment of extended x-ray absorption fine\nstructure. In agreement with this representation, we find a strong increase in\nthe atomic background with increasing q with a concomitant enhancement in the\namplitude of the extended fine structure. This effect should be generic and\nhence may enable improved measurement of the extended fine structure in a wide\nrange of materials containing low-Z elements."
    },
    {
        "anchor": "Structure and Dielectric Properties of Amorphous High-kappa Oxides:\n  HfO2, ZrO2 and their alloys: High-$\\kappa$ metal oxides are a class of materials playing an increasingly\nimportant role in modern device physics and technology. Here we report\ntheoretical investigations of the properties of structural and lattice\ndielectric constants of bulk amorphous metal oxides by a combined approach of\nclassical molecular dynamics (MD) - for structure evolution, and quantum\nmechanical first principles density function theory (DFT) - for electronic\nstructure analysis. Using classical MD based on the Born-Mayer-Buckingham\npotential function within a melt and quench scheme, amorphous structures of\nhigh-$\\kappa$ metal oxides Hf$_{1-x}$Zr$_x$O$_2$ with different values of the\nconcentration $x$, are generated. The coordination numbers and the radial\ndistribution functions of the structures are in good agreement with the\ncorresponding experimental data. We then calculate the lattice dielectric\nconstants of the materials from quantum mechanical first principles, and the\nvalues averaged over an ensemble of samples agree well with the available\nexperimental data, and are very close to the dielectric constants of their\ncubic form.",
        "positive": "Strongly Ideal Robust Weyl Semimetals in Cubic Symmetry with\n  Spatial-Inversion Breaking: We show that compounds in a family that possess time-reversal symmetry and\nshare a non-centrosymmetric cubic structure with the space group F-43m (No.\n216) host robust ideal Weyl semi-metal fermions with desirable topologically\nprotected features. The candidates in this family are compounds with different\nchemical formulas AB2, ABC, ABC2, and ABCD and their Fermi levels are\npredominantly populated by nontrivial Weyl fermions. Symmetry of the system\nrequires that the Weyl nodes with opposite chirality are well separated in\nmomentum space. Adjacent Weyl points have the same chirality, thus these Weyl\nnodes would not annihilate each other with respect to lattice perturbations. As\nFermi arcs and surface states connect Weyl nodes with opposite chirality, the\nlarge separation of the latter in momentum space guarantees the appearance of\nvery long arcs and surface states. This work demonstrates the use of system\nsymmetry by first-principles calculations as a powerful recipe for discovering\nnew Weyl semi-metals with attractive features whose protected fermions may be\ncandidates of many applications."
    },
    {
        "anchor": "Antisite disorder in the battery material LiFePO$_4$: We report detailed magnetometry and high-frequency electron spin resonance\n(HF-ESR) measurements which allow detailed investigation on Li-Fe antisite\ndisorder in single-crystalline LiFePO$_4$, i.e., exchange of Fe$^{2+}$- and\nLi$^+$-ions. The data imply that magnetic moments of Fe$^{2+}$-ions at\nLi-positions do not participate in long-range antiferromagnetic order in\nLiFePO$_4$ but form quasi-free moments. Anisotropy axes of the magnetic moments\nat antisite defects are attached to the main crystallographic directions. The\nlocal character of these moments is confirmed by associated linear resonance\nbranches detected by HF-ESR studies. Magnetic anisotropy shows up in\nsignificant zero-field splittings of $\\Delta = 220(3)$~GHz, $\\Delta'\\sim50$~GHz\nand a highly anisotropic $g$-factor, i.e., $g_\\mathrm{a} = 1.4$, $g_\\mathrm{b}\n= 2.0$, and $g_\\mathrm{c} = 6.3$. We demonstrate a general method to precisely\ndetermine Fe-antisite disorder in LiFePO$_4$ from magnetic studies which\nimplies a density of paramagnetic Fe$^{2+}$-ions at Li-positions of 0.53\\%.",
        "positive": "Disordered Electrical Potential Observed on the Surface of SiO$_2$ by\n  Electric Field Microscopy: The electrical potential on the surface of $\\sim 300$ nm thick SiO$_2$ grown\non single crystalline Si substrates has been characterized at ambient\nconditions using electric field microscopy. Our results show an inhomogeneous\npotential distribution with fluctuations up to $\\sim 0.4 $V within regions of\n$1 \\mu$m. The potential fluctuations observed at the surface of these usual\ndielectric holders of graphene sheets should induce strong variations in the\ngraphene charge densities and provide a simple explanation for some of the\nanomalous behaviors of the transport properties of graphene."
    },
    {
        "anchor": "Influence of Br$^{-}$/S$^{2-}$ site-exchange on Li diffusion mechanism\n  in Li$_6$PS$_5$Br -- a computational study: We investigate the influence of Br$^-$/S$^{2-}$ site-exchange on lithium\ndiffusion in the agyrodite-type solid electrolyte Li$_6$PS$_5$Br by ab-initio\nmolecular dynamics simulations. Based on the calculated trajectories a new\nmechanism for the internal lithium reorganization within the Li-cages around\nthe $4d$ sites is identified. This reorganization mechanism is highly concerted\nand cannot be described by one single rotation axis only. Simulations with\nBr$^-$/S$^{2-}$ defects reveal that Li$^._i$ interstitials are the dominant\nmobile charge carriers, which originate from Frenkel pairs. These are formed\nbecause Br$^._\\text{S}$ defects on the $4d$ sites cause the transfer of one or\neven two Li$^._i$ to the neighboring 12 cages. The lithium interstitials then\ncarry out intercage jumps via interstitial and interstitialcy mechanisms. With\nthat, one single Br$^._\\text{S}$ defect enables Li diffusion over an extended\nspatial area explaining why low degrees of site-exchange are sufficient to\ntrigger superionic conduction. The vacant sites of the Frenkel pairs, namely\nV$'_\\text{Li}$, are mostly immobile and bound to the Br$^._\\text{S}$ defect. To\na lesser degree also S$'_\\text{Br}$ defects induce disturbances in the lithium\ndistribution and act as sinks for lithium interstitials restricting the\nLi$^._i$ motion to the vicinity of the S$'_\\text{Br}$ defect.",
        "positive": "Photonic glass-ceramics: consolidated outcomes and prospects: Transparent glass-ceramics are nanocomposite materials which offer specific\ncharacteristics of capital importance in photonics. This kind of two-phase\nmaterials is constituted by nanocrystals embedded in a glass matrix and the\nrespective composition and volume fractions of crystalline and amorphous phase\ndetermine the properties of the glass-ceramic. Among these properties\ntransparency is crucial, in particular when confined structures, such as\ndielectric optical waveguides and optical fibers, are considered, and the\nnumber of papers devoted to this topic is continuously increasing. Another\nimportant point is the role of the nanocrystals when activated by luminescent\nspecies, as rare earth ions, and their effect on the spectroscopic properties\nof the glass-ceramic. The presence of the crystalline environment around the\nrare earth ion allows high absorption and emission cross sections, reduction of\nthe non-radiative relaxation thanks to the lower phonon cutoff energy, and\ntailoring of the ion-ion interaction by the control of the rare earth ion\npartition. This last point is crucial and still object of intense experimental\nand theoretical studies. The composition of the glass matrix also impacts the\nproperties of the rare earth ions located in nanoparticles. Moreover, some\nkinds of nanocrystals can play as effective rare earth sensitizers.\nFabrication, assessment and application of glass-ceramic photonic systems,\nespecially waveguides, deserve an appropriate discussion which is the aim of\nthis paper, focused on luminescent glass-ceramics. In this work, a brief\nhistorical review, consolidated results and recent advances in this important\nscientific and technological area will be presented, and some perspectives will\nbe outlined."
    },
    {
        "anchor": "Electronic structure of NaWO$_3$: Role of the impurity potential: We have performed {\\it ab-initio} electronic structure calculations to\ndetermine the evolution of the electronic structure of WO$_3$ with Na doping.\nNa doping introduces an additional electron when introduced into WO$_3$. The\nensuing electronic structure of Na doped WO$_3$, we find, is very similar to\nthe electronic structure of an electron introduced into WO$_3$, thus clarifying\nthe role of the impurity potential due to Na. While the electronic structure of\nNaWO$_3$ allows a rigid band like description over a certain energy range,\nmodifications introduced in the electronic structure can be related back to the\nelectron due to Na and not the impurity potential that one generally believes\nto be responsible.",
        "positive": "Anisotropic spin relaxation revealed by resonant spin amplification in\n  (110) GaAs quantum wells: We have studied spin dephasing in a high-mobility two-dimensional electron\nsystem (2DES), confined in a GaAs/AlGaAs quantum well grown in the [110]\ndirection, using the resonant spin amplification (RSA) technique. From the\ncharacteristic shape of the RSA spectra, we are able to extract the spin\ndephasing times (SDT) for electron spins aligned along the growth direction or\nwithin the sample plane, as well as the $g$ factor. We observe a strong\nanisotropy in the spin dephasing times. While the in-plane SDT remains almost\nconstant as the temperature is varied between 4 K and 50 K, the out-of-plane\nSDT shows a dramatic increase at a temperature of about 25 K and reaches values\nof about 100 ns. The SDTs at 4 K can be further increased by additional, weak\nabove-barrier illumination. The origin of this unexpected behavior is\ndiscussed, the SDT enhancement is attributed to the redistribution of charge\ncarriers between the electron gas and remote donors."
    },
    {
        "anchor": "First-principles studies of kinetics in epitaxial growth of III-V\n  semiconductors: We demonstrate how first-principles calculations using density-functional\ntheory (DFT) can be applied to gain insight into the molecular processes that\nrule the physics of materials processing. Specifically, we study the molecular\nbeam epitaxy (MBE) of arsenic compound semiconductors. For homoepitaxy of GaAs\non GaAs(001), a growth model is presented that builds on results of DFT\ncalculations for molecular processes on the beta2-reconstructed GaAs(001)\nsurface, including adsorption, desorption, surface diffusion and nucleation.\nKinetic Monte Carlo simulations on the basis of the calculated energetics\nenable us to model MBE growth of GaAs from beams of Ga and As_2 in atomistic\ndetail. The simulations show that island nucleation is controlled by the\nreaction of As_2 molecules with Ga adatoms on the surface. The analysis reveals\nthat the scaling laws of standard nucleation theory for the island density as a\nfunction of growth temperature are not applicable to GaAs epitaxy. We also\ndiscuss heteroepitaxy of InAs on GaAs(001), and report first-principles DFT\ncalculations for In diffusion on the strained GaAs substrate. In particular we\naddress the effect of heteroepitaxial strain on the growth kinetics of\ncoherently strained InAs islands. The strain field around an island is found to\ncause a slowing-down of material transport from the substrate towards the\nisland and thus helps to achieve more homogeneous island sizes.",
        "positive": "Strong room-temperature blue-violet photoluminescence of multiferroic\n  BaMnF$_4$: BaMnF$_4$ microsheets have been prepared by hydrothermal method. Strong\nroom-temperature blue-violet photoluminescence has been observed (absolute\nluminescence quantum yield 67%), with two peaks located at 385 nm and 410 nm,\nrespectively. More interestingly, photon self-absorption phenomenon has been\nobserved, leading to unusual abrupt drop of luminescence intensity at\nwavelength of 400 nm. To understand the underlying mechanism of such emitting,\nthe electronic structure of BaMnF$_4$ has been studied by first principles\ncalculations. The observed two peaks are attributed to electrons' transitions\nbetween the upper-Hubbard bands of Mn's $t_{2g}$ orbitals and the lower-Hubbard\nbands of Mn's $e_g$ orbitals. Those Mott gap mediated d-d orbital transitions\nmay provide additional degrees of freedom to tune the photon generation and\nabsorption in ferroelectrics."
    },
    {
        "anchor": "Shot-Peening of Pre-Oxidized Plates of Zirconium: Influence of Residual\n  Stress on Oxidation: The present study deals with oxidation behavior under residual stress of\nshot-peened plates of \"commercially pure\" zirconium exposed for 30 min at 650\nC. The influence of the shot-peening on a pre-oxidized material is presented.\nThe results have been used to determine the influences of these chemical\n(preoxidation) and mechanical (shot-peening) treatments on the high temperature\noxidation of zirconium. The oxygen profile was revealed using micro-hardness\ntechniques and confirmed by SEM-EDS techniques. After pre-oxidation the samples\nwere first resurfaced then shot-peened in order to introduce residual stress. A\nsignificant increase of the hardness of about 400 HV was observed on\npre-oxidized shot-peened samples. Thermogravimetric analysis for 30 min at 650\nC under 200 mbar O2 showed a significantly slower oxidation rate for\nshot-peened samples. A comparison with our computations points out the role of\nthe residual stresses on the diffusion and, consequently, on the oxidation.",
        "positive": "Convergence of the Bloch-waves method: We discuss in detail the Bloch waves method for calculation of energy and\norientation dependent scattering cross-section for inelastic scattering of\nelectrons on crystals. Convergence properties are investigated and a new\nalgorithm with superior timing and accuracy is described. The new method is\napplied to calculations of intensity of weakly excited spots, maps of magnetic\nsignal, and tilt series from zone axis orientation towards three-beam\norientation."
    },
    {
        "anchor": "Angular and temperature dependence of current induced spin-orbit\n  effective fields in Ta/CoFeB/MgO nanowires: Current induced spin-orbit effective magnetic fields in\nmetal/ferromagnet/oxide trilayers provide a new way to manipulate the\nmagnetization, which is an alternative to the conventional current induced spin\ntransfer torque arising from noncollinear magnetization. Ta/CoFeB/MgO\nstructures are expected to be useful for non-volatile memories and logic\ndevices due to its perpendicular anisotropy and large current induced\nspin-orbit effective fields. However many aspects such as the angular and\ntemperature dependent phenomena of the effective fields are little understood.\nHere, we evaluate the angular and temperature dependence of the current-induced\nspin-orbit effective fields considering contributions from both the anomalous\nand planar Hall effects. The longitudinal and transverse components of\neffective fields are found to have strong angular dependence on the\nmagnetization direction at 300 K. The transverse field decreases significantly\nwith decreasing temperature, whereas the longitudinal field shows weaker\ntemperature dependence. Our results reveal important features and provide an\nopportunity for a more comprehensive understanding of current induced\nspin-orbit effective fields.",
        "positive": "Reactivity screening of single atoms on modified graphene surface --\n  From formation and scaling relations to catalytic activity: Single atom catalysts (SACs) present the ultimate level of catalyst\nutilization, which puts them in the focus of current research. For this reason,\ntheir understanding is crucial for the development of new efficient catalytic\nsystems. Using Density Functional Theory calculations, model SACs consisted of\nnine metals (Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt and Au) on four different supports\n(pristine graphene, N- and B-doped graphene and graphene with single vacancy)\nwere analyzed. Among them, only graphene with a single vacancy enables the\nformation of SACs, which are stable in terms of aggregation and dissolution\nunder harsh conditions of electrocatalysis. Reactivity of models SACs was\nprobed using atomic (hydrogen and A = C, N, O and S) and molecular adsorbates\n(AHx, x = 1, 2, 3 or 4, depending on A), giving nearly 600 different systems\nincluded in this study. Scaling relations between adsorption energies of A and\nAHx on model SACs were confirmed. However, the scaling is broken for the case\nof CH3. There is also an evident scaling between adsorption energies of atomic\nand molecular adsorbates on metals SAs supported by pristine, N-doped and\nB-doped graphene, which originates from similar electronic structures of SAs on\nthese supports. Using the obtained data, we have analyzed the hydrogen\nevolution on the model SACs. Only M@graphene vacancy systems (excluding Ag and\nAu) are stable under hydrogen evolution conditions in highly acidic solutions.\nAdditional interfacial effects are discussed and the need for proper\ntheoretical treatment when studying SACs interactions with molecular species."
    },
    {
        "anchor": "Determining Spin Polarization of Seebeck Coefficients via Anomalous\n  Nernst Effect: Recently, Seebeck coefficients of ferromagnetic conductors are found to be\nspin-dependent. However straightforward method of accurately determining its\nspin polarization is still to be developed. Here, we have derived a linear\ndependence of anomalous Nernst coefficient on anomalous Hall angle with scaling\nfactor related to spin polarization of Seebeck coefficient, which has been\nexperimentally verified in [Co/Pt]n superlattices. Based on the dependence, we\nhave also evaluated spin polarization of Seebeck coefficient of some\nferromagnetic conductors. Besides, we have also found a new mechanism to\ngenerate pure spin current from temperature gradient in\nferromagnetic/nonmagnetic hybrid system, which could improve efficiency from\nthermal energy to spin current.",
        "positive": "Ultrabroadband photosensitivity from visible to terahertz at room\n  temperature: Charge-density wave (CDW) is one of the most fundamental quantum phenomena in\nsolids. Different from ordinary metals in which only single particle\nexcitations exist, CDW also has collective excitations and can carry electric\ncurrent in a collective fashion. Manipulating this collective condensation for\napplications has long been a goal in the condensed matter and materials\ncommunity. Here we show that the CDW system of 1T-TaS2 is highly sensitive to\nlight directly from visible down to terahertz, with current responsivities\naround the order of ~1 AW-1 at room temperature. Our findings open a new avenue\nfor realizing uncooled, ultrabroadband and sensitive photoelectronics\ncontinuously down to terahertz spectral range."
    },
    {
        "anchor": "Nature of the Breakdown in the Stokes-Einstein Relationship in a Hard\n  Sphere Fluid: Molecular Dynamics simulations of high density hard sphere fluids clearly\nshow a breakdown of the Stokes-Einstein equation (SE). This result has been\nconjectured to be due to the presence of mobile particles, i.e., ones which\nhave the propensity to \"hop\" distances which are integer multiples of the\ninterparticle distance. We conclusively show that, even though the whole liquid\nviolates the SE equation at high densities, the sedentary particles, i.e., ones\ncomplementary to the \"hoppers\", obey the SE relationship. These results\nstrongly support the notion that the unusual dynamics of fluids near\nvitrification are caused exclusively by the presence of hopping particles.",
        "positive": "Millikelvin LEED apparatus: a feasibility study: A low-energy electron diffraction (LEED) apparatus which works at\ntemperatures down to about 100 mK is designed to obtain structural information\nof 2D helium on graphite. This very low temperature system can be realized by\nreducing the thermal inflow from the LEED optics to the sample which is cooled\nby cryogen-free dilution refrigerator. The atomic scattering factor of He is\nalso estimated using a kinematical model, which suggests that the diffraction\nsignal from He atom can well be obtained by using a delay-line detector instead\nof a fluorescent screen."
    },
    {
        "anchor": "Magnetic Weyl semimetals with diamond structure realized in spinel\n  compounds: Diamond-structure materials have been extensively studied for decades, which\nform the foundation for most semiconductors and their modern day electronic\ndevices. Here, we discover a e$_g$-orbital ($d_{z^2}$,$d_{x^2-y^2}$ ) model\nwithin the diamond lattice (e$_g$-diamond model) that hosts novel topological\nstates. Specifically, the e$_g$-diamond model yields a 3D nodal cage (3D-NC),\nwhich is characterized by a $d$-$d$ band inversion protected by two types of\ndegenerate states (i.e., e$_g$-orbital and diamond-sublattice degeneracies). We\ndemonstrate materials realization of this model in the well-known spinel\ncompounds (AB$_2$X$_4$), where the tetrahedron-site cations (A) form the\ndiamond sub-lattice. An ideal half metal with one metallic spin channel formed\nby well-isolated and half-filled e$_g$-diamond bands, accompanied by a large\nspin gap (4.36 eV) is discovered in one 4-2 spinel compound (VMg$_2$O$_4$),\nwhich becomes a magnetic Weyl semimetal when spin-orbit coupling effect is\nfurther considered. Our discovery greatly enriches the physics of diamond\nstructure and spinel compounds, opening a door to their application in\nspintronics.",
        "positive": "Atomistic spin dynamics of the CuMn spin glass alloy: We demonstrate the use of Langevin spin dynamics for studying dynamical\nproperties of an archetypical spin glass system. Simulations are performed on\nCuMn (20% Mn) where we study the relaxation that follows a sudden quench of the\nsystem to the low temperature phase. The system is modeled by a Heisenberg\nHamiltonian where the Heisenberg interaction parameters are calculated by means\nof first-principles density functional theory. Simulations are performed by\nnumerically solving the Langevin equations of motion for the atomic spins. It\nis shown that dynamics is governed, to a large degree, by the damping parameter\nin the equations of motion and the system size. For large damping and large\nsystem sizes we observe the typical aging regime."
    },
    {
        "anchor": "Spatial mapping of disordered 2D materials: the conductance Sudoku: Motivated by recent advances on local conductance measurement techniques at\nthe nanoscale, timely questions are being raised about what possible\ninformation can be extracted from a disordered graphene sheet by selectively\ninterrogating its transport properties. Here we demonstrate how an inversion\ntechnique originally developed to identify the number of scatterers in a\nquantum device can be adapted to a multi-terminal setup in order to provide\ndetailed information about the spatial distribution of impurities on the\nsurface of graphene, as well as other 2D material systems. The methodology\ninput are conductance readings (for instance, as a function of the chemical\npotential) between different electrode pairs, the output being the spatially\nresolved impurity density. We discuss how the obtained spatial resolution\ndepends on the number of such readings and on the electrode geometry.\nFurthermore, by separating the impurity locations into partitions arranged in a\ngrid-like geometry, this inversion procedure resembles a Sudoku puzzle in which\nthe compositions of different sectors of a device are found by imposing that\nthey must add up to specific constrained values established for the grid rows\nand columns. We argue that this technique may provide alternative new ways of\nextracting information from a disordered material through the selective probing\nof local quantities.",
        "positive": "Ab initio parametrised model of strain-dependent solubility of H in\n  alpha-iron: The calculated effects of interstitial hydrogen on the elastic properties of\nalpha-iron from our earlier work are used to describe the H interactions with\nhomogeneous strain fields using ab initio methods. In particular we calculate\nthe H solublility in Fe subject to hydrostatic, uniaxial, and shear strain. For\ncomparison, these interactions are parametrised successfully using a simple\nmodel with parameters entirely derived from ab initio methods. The results are\nused to predict the solubility of H in spatially-varying elastic strain fields,\nrepresentative of realistic dislocations outside their core. We find a strong\ndirectional dependence of the H-dislocation interaction, leading to strong\nattraction of H by the axial strain components of edge dislocations and by\nscrew dislocations oriented along the critical < 111 > slip direction. We\nfurther find a H concentration enhancement around dislocation cores, consistent\nwith experimental observations."
    },
    {
        "anchor": "A comparative first-principles investigation on the defect chemistry of\n  TiO$_2$ anatase: Understanding native point defects is fundamental in order to comprehend the\nproperties of TiO$_2$ anatase in technological applications. Several\nfirst-principles studies have been performed in order to investigate the defect\nchemistry of this material. The reported values are, however, scattered over a\nwide range. In this manuscript we perform a comparative study employing\ndifferent approaches based on semilocal, DFT+$U$ and screened hybrid\nfunctionals in order to investigate the dependence of defect properties, such\nas formation energies and charge transition levels, on the employed\ncomputational method. While the defects in anatase, like in most\ntransition-metal oxides, generally induce the localization of electrons or\nholes on atomic sites, we notice that, provided an alignment of the valence\nbands has been performed, the calculated defect formation energies and\ntransition levels using semi-local functionals are in a fair agreement with\nthose obtained using hybrid functionals. A similar conclusion can be reached\nfor the thermochemistry of the Ti-O system and the limit values of the\nelemental chemical potentials. We interpret this as a cancellation of error\nbetween the self-interaction error and the overbinding of the O$_2$ molecule in\nsemi-local functionals. Inclusion of a $U$ term in the electron Hamiltonian\noffers a convenient way for obtaining more precise geometric and electronic\nconfigurations of the defective systems.",
        "positive": "Nonexistence of \"Spin Transverse Force\" for a Relativistic Electron: Using the complete Dirac Hamiltonian for a relativistic electron it is shown\nthat the spin transverse force derived by S.Q. Shen, Phys. Rev. Lett. 95,\n187203 (2005) does not exist. This force is an artefact resulting from an\napproximate form of the employed Hamiltonian."
    },
    {
        "anchor": "Carbon Nanotube Wools Directly from CO2 By Molten Electrolysis Value\n  Driven Pathways to Carbon Dioxide Greenhouse Gas Mitigation: A climate mitigation comprehensive solution is presented through the first\nhigh yield, low energy synthesis of macroscopic length carbon nanotubes (CNT)\nwool from CO2 by molten carbonate electrolysis, suitable for weaving into\ncarbon composites and textiles. Growing CO2 concentrations, the concurrent\nclimate change and species extinction can be addressed if CO2 becomes a sought\nresource rather than a greenhouse pollutant. Inexpensive carbon composites\nformed from carbon wool as a lighter metal, textiles and cement replacement\ncomprise a major market sink to compactly store transformed anthropogenic CO2.\n100x-longer CNTs grow on Monel versus steel. Monel, electrolyte equilibration,\nand a mixed metal nucleation facilitate the synthesis. CO2, the sole reactant\nin this transformation, is directly extractable from dilute (atmospheric) or\nconcentrated sources, and is cost constrained only by the (low) cost of\nelectricity. Today's $100K per ton CNT valuation incentivizes CO2 removal.",
        "positive": "Structure, elastic and dynamical properties of KN$_3$ and RbN$_3$: A van\n  der Waals density functional study: We report a detailed first principles study on the structural, elastic,\nvibrational and thermodynamic properties of layered structure energetic alkali\nmetal azides KN$_3$ and RbN$_3$. All the calculations were carried out by means\nof plane wave pseudopotential method with and without including van der Waals\ninteractions. The calculated ground state structural properties are improved to\na greater extent by the inclusion of dispersion corrections, implies that the\nvan der Waals interactions play a major role on the physical properties of\nthese systems. The elastic constants and the related bulk mechanical properties\nfor the tetragonal KN$_3$ and RbN$_3$ have been calculated using both the\nmethods and found that the compounds are mechanically stable systems. The\nmagnitude of the calculated elastic constants increases in the order RbN$_3$\n$<$ KN$_3$ implying higher elastic stiffness for KN$_3$, the fact also\nconfirmed by the higher values of bulk, shear and Young's moduli of KN$_3$ than\nRbN$_3$. Moreover, the calculated elastic constants follows the inequality\nC$_{33}$ $<$ C$_{11}$ which indicates the presence of more number of\nintermolecular interactions along a-axis over c-axis of the azide lattices. A\ncorrelation has been proposed to relate the calculated elastic constants to the\ndecomposition phenomena for the metal azides. The experimentally reported\nvibrational frequencies at the gamma point were exactly reproduced by the\npresent calculations. In addition, we also present the thermodynamic properties\nsuch as heat capacity which compares well with the experiment."
    },
    {
        "anchor": "Magnetic properties and magnetostructural phase transitions in\n  Ni2+xMn1-xGa shape memory alloys: A systematic study of magnetic properties of Ni2+xMn1-xGa (0 \\le x \\le 0.19)\nHeusler alloys undergoing structural martensite-austenite transformations while\nin ferromagnetic state has been performed. From measurements of spontaneous\nmagnetization, Ms(T), jumps \\Delta M at structural phase transitions were\ndetermined. Virtual Curie temperatures of the martensite were estimated from\nthe comparison of magnetization in martensitic and austenitic phases. Both\nsaturation magnetic moments in ferromagnetic state and effective magnetic\nmoments in paramagnetic state of Mn and Ni atoms were estimated and the\ninfluence of delocalization effects on magnetism in these alloys was discussed.\nThe experimental results obtained show that the shift of martensitic transition\ntemperature depends weakly on composition. The values of this shift are in good\ncorrespondence with Clapeyron-Clausius formalism taking into account the\nexperimental data on latent heat at martensite-austenite transformations.",
        "positive": "Type-II Nodal Line Fermions in New Z2 Topological Semimetals AV6Sb6\n  (A=K, Rb,and Cs) with Kagome Bilayer: The recently discovered layered kagome metals AV3Sb5 (A=K, Rb, and Cs)\nattract intensive interest due to their intertwining with superconductivity,\ncharge-density-wave state, and nontrivial band topology. In this work, we show\nby first-principles calculations and symmetry arguments that unconventional\ntype-II Dirac nodal line fermions close to the fermi level are present in\nanother latest class of experimentally synthesized kagome compounds AV6Sb6\n(A=K, Rb, and Cs). These compounds possess a unique kagome (V3Sb)2 bilayer that\ndominates their electronic and topological properties, instead of the kagome\nV3Sb monolayer in AV3Sb5. Crystal symmetry guarantees that the type-II Dirac\nnodal lines with quantized Berry phase lie in reflection-invariant planes of\nthe Brillouin zone. We further reveal that the type-II Dirac nodal lines remain\nnearly intact in the presence of spin-orbital coupling and can be categorized\nas a Z2 classification. The findings establish AV6Sb6 as a class of new\nfascinating prototypes, which will extend the knowledge of interplay between\nunconventionally topological fermions and exotic quantum ordered states in\nkagome systems."
    },
    {
        "anchor": "Manipulating exchange bias using all-optical helicity-dependent\n  switching: Deterministic all-optical control of magnetization without an applied\nmagnetic field has been reported for different materials such as ferrimagnetic\nand ferromagnetic thin films and granular recording media. These findings have\nchallenged the understanding of all-optical helicity-dependent switching of\nmagnetization and opened many potential applications for future magnetic\ninformation, memory and storage technologies. Here we demonstrate optical\ncontrol of an antiferromagnetic layer through the exchange bias interaction\nusing the helicity of a femtosecond pulsed laser on IrMn/[Co/Pt]xN\nantiferromagnetic/ ferromagnetic heterostructures. We show controlled switching\nof the sign of the exchange bias field without any applied field, only by\nchanging the helicity of the light, and quantify the influence of the laser\nfluence and the number of light pulses on the exchange bias control. We also\npresent the combined effect of laser pulses and applied magnetic field. This\nstudy opens applications in spintronic devices where the exchange bias\nphenomenon is routinely used to fix the magnetization orientation of a magnetic\nlayer in one direction.",
        "positive": "Quantum anomalous Hall phase in (001) double-perovskite monolayers via\n  intersite spin-orbit coupling: Using tight-binding models and first-principles calculations, we demonstrate\nthe possibility to achieve a quantum anomalous Hall (QAH) phase on a\ntwo-dimensional square lattice, which can be realized in monolayers of double\nperovskites. We show that effective intersite spin-orbit coupling between eg\norbitals can be induced perturbatively, giving rise to a QAH state. Moreover,\nthe effective spin-orbit coupling can be enhanced by octahedral rotations.\nBased on first-principles calculations, we propose that this type of QAH state\ncould be realized in La2MnIrO6 monolayers, with the size of the gap as large as\n26 meV in the ideal case. We observe that the electronic structure is sensitive\nto structural distortions, and that an enhanced Hubbard U tends to stabilize\nthe nontrivial gap."
    },
    {
        "anchor": "Maximally localized Wannier functions within the (L)APW+LO method: We present a robust algorithm that computes (maximally localized) Wannier\nfunctions (WFs) without the need of providing an initial guess. Instead, a\nsuitable starting point is constructed automatically from so-called local\norbitals which are fundamental building blocks of the basis set within\n(linearized) augmented planewave methods. Our approach is applied to a vast\nvariety of materials such as metals, bulk and low-dimensional semiconductors,\nand complex inorganic-organic hybrid interfaces. For the interpolation of\nelectronic single-particle energies, an accuracy in the meV range can be easily\nachieved. We exemplify the capabilities of our method by the calculation of the\njoint density of states in aluminum, (generalized) Kohn-Sham and quasi-particle\nband structures in various semiconductors, and the electronic structure of\n$\\beta$-Ga$_2$O$_3$, including electron and hole effective masses.",
        "positive": "Chemical Doping and Enhanced Solar Energy Conversion of Graphene/Silicon\n  Junctions: The effect of chemical doping of graphene films on the photovoltaic\nproperties of the graphene/silicon Schottky junction solar cells was\ninvestigated. Thionyl chloride modification greatly enhanced the conductivity\nof graphene film, resulting in a significant improvement in cell performance\nwith a 3-fold increase in conversion efficiency (up to 3.9%) and good\nshort-term stability."
    },
    {
        "anchor": "Two-step transition in a magnetoelectric ferrimagnet Cu2OSeO3: We report a detailed single crystal investigation of a magnetoelectric\nferrimagnet Cu2OSeO3 using dc magnetization and ac susceptibility along the\nthree principal directions [100], [110] and [111]. We have observed that in\nsmall magnetic fields two magnetic transitions occur, one at Tc = 57 K and the\nsecond one at TN = 58 K. At Tc the non-linear susceptibility reveals the\nemergence of the ferromagnetic component and below Tc the magnetization\nmeasurements show the splitting between field-cooled and zero-field-cooled\nregimes. Above 1000 Oe the magnetization saturates and the system is in a\nsingle domain state. The temperature dependence of the saturation below Tc can\nbe well described by m(T) = m(0)[1 - (T/Tc)^2]^{\\beta}, with m(0) = 0.56\n(mu)B/Cu, corresponding to the 3-up-1-down configuration. The dielectric\nconstant measured on a thin single crystal shows a systematic deviation below\nthe transition, indicating an intrinsic magnetoelectric effect.",
        "positive": "Magnetization Enhancement in Magnetite Nanoparticles Capped with Alginic\n  Acid: We report on the effect of organic acid capping on the behavior of magnetite\nnanoparticles. The nanoparticles of magnetite were obtained using microwave\nactivated process, and the magnetic properties as well as the electron magnetic\nresonance behavior were studied for the Fe3O4 nanoparticles capped with alginic\nacid. The capped nanoparticles exhibit improved crystalline structure of the\nsurface which leads to an enhanced magnetization. The saturation magnetization\nMs increases to ~75% of the bulk magnetization. The improved structure also\nfacilitates quantization of spin-wave spectrum in the finite size nanoparticles\nand this in turn is responsible for unconventional behavior at low\ntemperatures. In magnetic resonance these anomalies are manifested as an\nunusual increase in the resonant field Hr(T) and also as a maximum of the\nspectroscopic splitting geff parameter at low temperatures. The unconventional\nbehavior of the nanoparticles also leads to pronounced upturn of magnetization\nat low temperatures and a deviation from the Bloch law M(T) T^3/2."
    },
    {
        "anchor": "Nucleation mechanism for the direct graphite-to-diamond phase transition: Graphite and diamond have comparable free energies, yet forming diamond from\ngraphite is far from easy. In the absence of a catalyst, pressures that are\nsignificantly higher than the equilibrium coexistence pressures are required to\ninduce the graphite-to-diamond transition. Furthermore, the formation of the\nmetastable hexagonal polymorph of diamond instead of the more stable cubic\ndiamond is favored at lower temperatures. The concerted mechanism suggested in\nprevious theoretical studies cannot explain these phenomena. Using an ab initio\nquality neural-network potential we performed a large-scale study of the\ngraphite-to-diamond transition assuming that it occurs via nucleation. The\nnucleation mechanism accounts for the observed phenomenology and reveals its\nmicroscopic origins. We demonstrated that the large lattice distortions that\naccompany the formation of the diamond nuclei inhibit the phase transition at\nlow pressure and direct it towards the hexagonal diamond phase at higher\npressure. The nucleation mechanism proposed in this work is an important step\ntowards a better understanding of structural transformations in a wide range of\ncomplex systems such as amorphous carbon and carbon nanomaterials.",
        "positive": "A new structural relaxation pathway of low-density amorphous ice: Low-density amorphous ice (LDA) is involved in critical cosmological\nprocesses and has gained prominence as one of the at least two distinct\namorphous forms of ice. Despite these accolades, we still have an incomplete\nunderstanding of the structural diversity that is encompassed within the LDA\nstate and the dynamic processes that take place upon heating LDA. Heating the\nhigh-pressure ice VIII phase at ambient pressure is a remarkable example of\ntemperature-induced amorphisation yielding LDA. We investigate this process in\ndetail using X-ray diffraction and Raman spectroscopy, and show that the LDA\nobtained from ice VIII is structurally different from the more 'traditional'\nstates of LDA which are approached upon thermal annealing. This new structural\nrelaxation pathway involves an increase of structural order on the intermediate\nrange length scale. In contrast with other LDA materials the local structure is\nmore ordered initially and becomes slightly more disordered upon annealing. We\nalso show that the cascade of phase transitions upon heating ice VIII at\nambient pressure includes the formation of ice IX which may be connected with\nthe structural peculiarities of LDA from ice VIII. Overall, this study shows\nthat LDA is a structurally more diverse material than previously appreciated."
    },
    {
        "anchor": "Point defects at cleaved Sr$_{n+1}$Ru$_n$O$_{3n+1}$(001) surfaces: The (001) surfaces of cleaved Sr$_3$Ru$_2$O$_7$ and Sr$_2$RuO$_4$ samples\nwere investigated using low-temperature scanning tunneling microscopy and\ndensity functional theory calculations. Intrinsic defects are not created\nduring cleaving. This experimental observation is consistent with calculations,\nwhere the formation energy for a Sr and O vacancy, 4.19 eV and 3.81 eV,\nrespectively, is significantly larger than that required to cleave the crystal,\n1.11 eV/(1 $\\times$ 1) unit cell. Surface oxygen vacancies can be created\nthrough electron bombardment, however, and their appearance is shown to vary\nstrongly with the imaging conditions. Point defects observed on as-cleaved\nsurfaces result from bulk impurities and adsorption from the residual gas.",
        "positive": "I-V analysis of high-energy lithium-ion-irradiated Si and GaAs solar\n  cells: Space-grade Si and GaAs solar cells were irradiated with 15 and 40 MeV\nlithium ions. Dark-IV analysis (with and without illumination) reveals\ndifferences in the effects of such irradiation on the different cell types"
    },
    {
        "anchor": "Raman signatures of monoclinic distortion in\n  (Ba$_{1-x}$Sr$_{x}$)$_{3}$CaNb$_{2}$O$_{9}$ complex perovskites: Octahedral tilting is most common distortion process observed in\ncentrosymmetric perovskite compounds (ABO$_{3}$). Indeed, crucial physical\nproperties of this oxide stem from the tilts of BO$_{6}$ rigid octahedra. In\nmicrowave ceramics with perovskite-type structure, there is a close relation\nbetween the temperature coefficient of resonant frequency and tilt system of\nthe perovskite structure. However, in many cases, limited access facilities are\nneeded to assign correctly the space group, including neutron scattering and\ntransmission electron microscopy. Here, we combine the Raman scattering and\ngroup-theory calculations to probe the structural distortion in the perovskite\n(Ba$_{1-x}$Sr$_{x}$)$_{3}$CaNb$_{2}$O$_{9}$ solid solution, which exhibits a\nstructural phase transition at $x$ $\\geq$ 0.7, from D$_{3d}^{3}$ trigonal to\nC$_{2h}^{3}$ monoclinic cell. Both phases are related by an octahedral tilting\ndistortion ($a^{0}b^{-}b^{-}$ in Glazer notation). Low temperature Raman\nspectra corroborate the group-theoretical predictions for\nSr$_{3}$CaNb$_{2}$O$_{9}$ compound, since 36 modes detected at 25 K agree well\nwith those 42 (25A$_{g}$ $\\oplus$ 17B$_{g}$) predicted ones.",
        "positive": "Phosphorus cluster production by laser ablation: Neutral and charged phosphorus clusters of a wide size range have been\nproduced by pulsed laser ablation (PLA) in vacuum at 532, 337, and 193 nm\nablating wavelengths and investigated by time-of-flight mass spectrometry. The\nneutral P_n clusters are even-numbered with local abundance maxima at n = 10\nand 14, while the cationic and anionic clusters are preferentially odd-numbered\nwith (P_7)+, (P_21)+, and (P_17)- being the most abundant ions. The dominance\nof the magic clusters is more pronounced at 337-nm ablation that is explained\nby efficient direct ejection of their building blocks under these conditions.\nNanocrystalline phosphorus films have been produced by PLA in ambient helium\ngas."
    },
    {
        "anchor": "Ultrafast modulation of the molten metal surface tension under\n  femtosecond laser irradiation: We predict ultrafast modulation of the pure molten metal surface stress\nfields under the irradiation of the single femtosecond laser pulse through the\ntwo-temperature model molecular-dynamics simulations. High-resolution and\nprecision calculations are used to resolve the ultrafast laser-induced\nanisotropic relaxations of the pressure components on the time-scale comparable\nto the intrinsic liquid density relaxation time. The magnitudes of the dynamic\nsurface tensions are found being modulated sharply within picoseconds after the\nirradiation, due to the development of the nanometer scale non-hydrostatic\nregime behind the exterior atomic layer of the liquid surfaces. The reported\nnovel regulation mechanism of the liquid surface stress field and the dynamic\nsurface tension hints at levitating the manipulation of liquid surfaces, such\nas ultrafast steering the surface directional transport and patterning.",
        "positive": "Accentuating the Competency of $3d$ Transition Metal Doped $Mg_4$\n  Clusters towards Molecular Hydrogen Adsorption: A DFT Study: Density functional theory $(DFT)$ studies show that doping of $3d TM$ atoms\ninto $Mg_4^{0,+} (TMMg_3^{0,+})$ can alter the endothermic nature of molecular\nhydrogen adsorption on bare $Mg_4^{0,+}$. $H_2$ adsorption on $TMMg_3^{0,+}$\nclusters depends on the $TM(3d)$ orbital contribution to the frontier molecular\norbitals of the clusters. In $H_2TMMg_3^{0,+}$ complexes, $H_2$ is adsorbed\nthrough donation and back donation of electronic charges with $TMMg_3^{0,+}$\nclusters. $H_2$ binding energy is the maximum for $NiMg_3$ (-0.76 eV) and\n$FeMg_3^+$ (-0.48 eV) among the neutral and cationic $TMMg_3$ clusters,\nrespectively. The geometry of $H_2$ adsorption complex entirely depends on the\ngeometry of the host cluster. The lowest energy symmetrical structures of both\n$NiMg_3$ and $FeMg_3^+$ clusters are less efficient than some slightly higher\nenergy low symmetrical geometrical isomers for adsorption of multiple hydrogen\nmolecules (13.28 $H_2$ $wt\\%$ for $NiMg_3$ and 7.89 $H_2$ $wt\\%$ for\n$FeMg_3^+$). Greater exposer of $TM^{0,+}$ along with its lower Mg coordination\nnumber make host clusters more suitable for hydrogen storage."
    },
    {
        "anchor": "A comprehensive study of the (2R3x2R3)R30 structure of silicene on\n  Ag(111): The deposition of one silicon monolayer on Ag(111) gives rise to a set of\nsuperstructures depending on growth conditions. These superstructures are\ncorrelated to the epitaxy between the honeycomb structure of silicon (so called\nsilicene) and the silver substrate. In this paper, from a detailed re-analysis\nof experimental results, obtained by Scanning Tunneling Microscopy and by Low\nEnergy Electron Diffraction on the (2R3x2R3)R30 structure, we propose a new\natomic model of the silicene layer based on periodic arrangements of perfect\nareas of (2R3x2R3)R30 surrounded by defect areas. A generalization of this\nmodel explains the main experimental observations: deviation of the average\ndirection, Moire patterns and apparent global disorder. In the frame of the\nproposed model, the apparent disorders observed on the STM images, would be\ntopological effects, i.e. the silicene would keep a quasi-perfect honeycomb\nstructure.",
        "positive": "Effect of Low-Damage Inductively Coupled Plasma on Shallow NV Centers in\n  Diamond: Near-surface nitrogen-vacancy ({NV}) centers in diamond have been\nsuccessfully employed as atomic-sized magnetic field sensors for external spins\nover the last years. A key challenge is still to develop a method to bring NV\ncenters at nanometer proximity to the diamond surface while preserving their\noptical and spin properties. To that aim we present a method of controlled\ndiamond etching with nanometric precision using an oxygen inductively coupled\nplasma (ICP) process. Importantly, no traces of plasma-induced damages to the\netched surface could be detected by X-ray photoelectron spectroscopy (XPS) and\nconfocal photoluminescence microscopy techniques. In addition, by profiling the\ndepth of NV centers created by 5.0 keV of nitrogen implantation energy, no\nplasma-induced quenching in their fluorescence could be observed. Moreover, the\ndeveloped etching process allowed even the channeling tail in their depth\ndistribution to be resolved. Furthermore, treating a 12C isotopically purified\ndiamond revealed a threefold increase in T2 times for NV centers with <4 nm of\ndepth (measured by NMR signal from protons at the diamond surface) in\ncomparison to the initial oxygen-terminated surface."
    },
    {
        "anchor": "First-principles study of the lattice and electronic structures of\n  TbMn$_2$O$_5$: The structural, electronic and lattice dielectric properties of multiferroic\nTbMn$_2$O$_5$ are investigated using density functional theory within the\ngeneralized gradient approximation (GGA). We use collinear spin approximations\nand ignore the spin-orbit coupling. The calculated structural parameters are in\nexcellent agreement with the experiments. We confirm that the ground state\nstructure of TbMn$_2$O$_5$ is of space group $Pb2_1m$, allowing polarizations\nalong the b-axis. The spontaneous electric polarization is calculated to be\n1187 $nC\\cdot$cm$^{-2}$. The calculated zone-center optical phonons frequencies\nand the oscillator strengths of IR phonons agree very well with the\nexperimental values. We then derive an effective Hamiltonian to explain the\nmagnetically-induced ferroelectricity in this compound. Our results strongly\nsuggest that the ferroelectricity in TbMn$_2$O$_5$ is driven by the magnetic\nordering that breaks the the inversion symmetry, without invoking the\nspin-orbit coupling.",
        "positive": "Solving the Crystallographic Phase Problem using Dynamical Scattering in\n  Electron Diffraction: Solving crystal structures from kinematical X-ray or electron diffraction\npatterns of single crystals requires many more diffracted beams to be recorded\nthan there are atoms in the structure, since the phases of the structure\nfactors can only be retrieved from such data if the atoms can be resolved as\nsharply peaked objects. Here a method is presented by which the fact that\nmultiple scattering encodes structure factor phases in the diffracted\nintensities is being used for solving the crystallographic phase problem. The\nretrieval of both amplitudes and phases of electron structure factors from\ndiffraction patterns recorded with varying angle of incidence will be\ndemonstrated. No assumption about the scattering potential itself is being\nmade. In particular, the resolution in the diffraction data does not need to be\nsufficient to resolve atoms, making this method potentially interesting for\nelectron crystallography of 2-dimensional protein crystals and other\nbeam-sensitive complex structures."
    },
    {
        "anchor": "Berry Curvature Signatures in Chiroptical Excitonic Transitions: The topology of the electronic band structure of solids can be described by\nits Berry curvature distribution across the Brillouin zone. We theoretically\nintroduce and experimentally demonstrate a general methodology based on the\nmeasurement of energy- and momentum-resolved optical transition rates, allowing\nto reveal signatures of Berry curvature texture in reciprocal space. By\nperforming time- and angle-resolved photoemission spectroscopy of atomically\nthin WSe$_2$ using polarization-modulated excitations, we demonstrate that\nexcitons become an asset in extracting the quantum geometrical properties of\nsolids. We also investigate the resilience of our measurement protocol against\nultrafast scattering processes following direct chiroptical transitions.",
        "positive": "Indirect Optical Absorption of Single Crystalline beta-FeSi2: We investigated optical absorption spectra near the fundamental absorption\nedge of beta-FeSi2 single crystals by transmission measurements. The phonon\nstructure corresponding to the emission and absorption component was clearly\nobserved in the low-temperature absorption spectra. Assuming exciton state in\nthe indirect allowed transition, we determined a phonon energy of 0.031 +-\n0.004 eV. A value of 0.814 eV was obtained for the exciton transition energy at\n4K."
    },
    {
        "anchor": "Ultrasound as a probe of dislocation density in aluminum: Dislocations are at the heart of the plastic behavior of crystalline\nmaterials yet it is notoriously difficult to perform quantitative,\nnon-intrusive, measurements of their single or collective properties.\nDislocation density is a critical variable that determines dislocation\nmobility, strength and ductility. On the one hand, individual dislocations can\nbe probed in detail with transmission electron microscopy. On the other hand,\ntheir collective properties must be simulated numerically. Here we show that\nultrasound technology can be used to measure dislocation density. This\ndevelopment rests on theory---a generalization of the Granato-L\\\"ucke theory\nfor the interaction of elastic waves with dislocations---and Resonant\nUltrasound Spectroscopy (RUS) measurements. The chosen material is aluminum, to\nwhich different dislocation contents were induced through annealing and cold\nrolling processes. The dislocation densities obtained with RUS compare\nfavorably with those inferred from X-ray diffraction, using the modified\nWilliamson-Hall method.",
        "positive": "Transport properties of the top and bottom surfaces in monolayer MoS2\n  grown by chemical vapor deposition: The advantage of MoS2, compared with graphene, is the direct growth on\nvarious oxide substrates by chemical vapor deposition (CVD) without utilizing\ncatalytic metal substrates, which facilitates practical applications for\nelectronics. The carrier mobility is, however, degraded from the intrinsic\nlimit mainly due to short-range scattering caused by S vacancies formed during\nCVD growth. If the upper limit for the crystallinity of CVD-MoS2 on oxide\nsubstrates is determined by the MoS2/substrate interaction during growth, it\nwill hinder the advantage. In this study, we investigated the interaction\nbetween monolayer MoS2 and a SiO2/Si substrate and the difference in\ncrystallinity between the top and bottom S surfaces due to the MoS2/substrate\ninteraction. Raman and photoluminescence spectroscopy indicated that doping and\nstrain were induced in MoS2 from the substrate, but they could be removed by\ntransferring MoS2 to a new substrate using polymers. The newly developed\npolymer-transfer technique enabled selective transfer of the bottom or top\nsurface of CVD-MoS2 onto a new SiO2/Si substrate. The metal-insulator\ntransition was clearly observed for both the normal and inverse transfers,\nsuggesting that the crystallinity of CVD-MoS2 is high and that the\ncrystallinity of the bottom surface interacting with the substrate was similar\nto that of the top free surface. These results provide positive prospects for\nthe further improvement of the crystallinity of MoS2 on oxide substrates by\nreconsidering the growth conditions."
    },
    {
        "anchor": "Elastic anisotropy in heterogeneous materials: Heterogeneous materials exhibit anisotropy to varying extent that is\ninfluenced by factors such as individual phase properties and microstructural\nconfiguration. A review of the existing anisotropy measures proposed in the\ncontext of single crystals reveal that they do not account for the material and\nmicrostructural descriptors influencing the extent of anisotropy in\nheterogeneous materials. To overcome this limitation, existing anisotropy\nindices have been re-interpreted by considering the effective elastic\nproperties of heterogeneous materials obtained by appropriate homogenization\ntechniques. Anisotropy quantification has been demonstrated considering two\nphase composite materials highlighting the role of constituent volume\nfractions, secondary phase shape and elastic contrast in influencing the extent\nof anisotropy. Specific cases leading to overall isotropy in two phase\ncomposite materials and extension of the approach to consider porosity and\ncracks have also been presented demonstrating the applicability of the approach\nto any class of heterogeneous materials thus filling a crucial gap in the\nexisting literature.",
        "positive": "Surface versus bulk state in topological insulator Bi2Se3 under\n  environmental disorder: Topological insulators (TIs) are predicted to be composed of an insulating\nbulk state along with conducting channels on the boundary of the material. In\nBi2Se3, however, the Fermi level naturally resides in the conduction band due\nto intrinsic doping by selenium vacancies, leading to metallic bulk states. In\nsuch non-ideal TIs it is not well understood how the surface and bulk states\nbehave under environmental disorder. In this letter, based on transport\nmeasurements of Bi2Se3 thin films, we show that the bulk states are sensitive\nto environmental disorder but the surface states remain robust."
    },
    {
        "anchor": "Synthesis of novel rare earth - iron oxide chalcogenides with the\n  La2Fe2O3Se2 structure: Our searches for new oxide chalcogenides of rare earths and Fe, Co, Ni, and\nZn resulted in preparation of two new compounds Ce2Fe2O3S2 and Pr2Fe2O3S2 which\nare isostructural to La2Fe2O3Se2 and Sm2Ti2O3Sb2. Crystal structures of the new\ncompounds Ce2Fe2O3S2 and Pr2Fe2O3S2 were determined from powder X-ray\ndiffraction data. Magnetic measurements were performed for Ce2Fe2O3S2 and\nrevealed behavior very similar to that of isostructural oxide chalcogenides of\niron and pnictides of titanium. In particular, no superconductivity was\nobserved down to 4 K. Crystal chemical factors determining the stability of the\nLa2Fe2O3Se2 structure type are discussed.",
        "positive": "Time of Flight Transients in the Dipolar Glass Model: Using Monte Carlo simulation we investigated time of flight current\ntransients predicted by the dipolar glass model for a random spatial\ndistribution of hopping centers. Behavior of the carrier drift mobility was\nstudied at room temperature over a broad range of electric field and sample\nthickness. A flat plateau followed by $j\\propto t^{-2}$ current decay is the\nmost common feature of the simulated transients. Poole-Frenkel mobility field\ndependence was confirmed over 5 to 200 V/$\\mu$m as well as its independence of\nthe sample thickness. Universality of transients with respect to both field and\nsample thickness has been observed. A simple phenomenological model to describe\nsimulated current transients has been proposed. Simulation results agree well\nwith the reported Poole-Frenkel slope and shape of the transients for a\nprototype molecularly doped polymer."
    },
    {
        "anchor": "Exciton and interband optical transitions in hBN single crystal: Near band gap photoluminescence (PL) of hBN single crystal has been studied\nat cryogenic temperatures with synchrotron radiation excitation. The PL signal\nis dominated by the D-series previously assigned to excitons trapped on\nstructural defects. A much weaker S-series of self-trapped excitons at 5.778 eV\nand 5.804 eV has been observed using time-window PL technique. The S-series\nexcitation spectrum shows a strong peak at 6.02 eV, assigned to free exciton\nabsorption. Complementary photoconductivity and PL measurements set the band\ngap transition energy to 6.4 eV and the Frenkel exciton binding energy larger\nthan 380 meV.",
        "positive": "Investigation of interface spacing, stability, band offsets and\n  electronic properties on (001) SrHfO3/GaAs interface : First principles\n  calculations: SrHfO3 is a potential dielectric material for metal-oxide-semiconductor (MOS)\ndevices. SrHfO3/GaAs interface has attracted attention due to its unique\nproperties. In this paper, the interface properties of (001) SrHfO3/GaAs are\ninvestigated by frst principles calculations based on density functional theory\n(DFT). Firstof all, the adsorption behavior of Sr, Hf and O on GaAs surface is\ninvestigated. O has lower adsorption energy on Ga surface than on As surface.\nThen, some possible (0 0 1) SrHfO3/GaAs confgurations are considered to analyze\nthe interface spacing, stability, band offsets and charge transfer. HfO2/Ga(2)\nand SrO/Ga(1) configurations in binding energy are lower than other interface\nconfigurations, indicating that they are more stable. At last, we study the\nelectronic properties of HfO2/Ga(2) and SrO/Ga(1) configurations. The\nelectronic density of states suggests that the systems exhibit metallic\nbehavior. The band offset and charge transfer are related to the interface\nspacing. The valence band offset (VBO) and charge transfer will decrease with\nincreasing interface spacing."
    },
    {
        "anchor": "Draw out Carbon Nanotube from Liquid Carbon: Carbon nanotube (CNT) is expected for much more important and broader\napplications in the future, because of its amazing electrical and mechanical\nproperties. However, today, the prospect is detained by the fact that the\ngrowth of CNTs cannot be well controlled. In particular, controlling the\nchirality of CNTs seems formidable to any existing growth method. In addition,\na systematic method for a designed interconnected network has not been\nestablished yet, which is focused particularly in nano-electronics field. Up to\nnow, there is a strong need for novel synthetic method that is controllable for\nchirality and architecture and applicable to mass production. Recently, the\nexperimental evidences were reported for the growth of pure carbon-arc-product\nnanotubes from a liquid precursor. Here we show the simulation results of\nelongated growth process of CNT by drawing out a well-formed nanotube from\nliquid carbon and discuss the mechanism and suitable synthesis conditions. The\nprocess is also simulated for creation of a Y junction from two isolated CNTs\nas first step to CNT network. We propose this novel synthetic method as a\npromising one for catalyst-free mechanical design of interconnected CNT network\nand CNT cloning.",
        "positive": "Graphane: a two-dimensional hydrocarbon: We predict the stability of a new extended two-dimensional hydrocarbon on the\nbasis of first-principles total energy calculations. The compound that we call\ngraphane is a fully saturated hydrocarbon derived from a single graphene sheet\nwith formula CH. All of the carbon atoms are in sp3 hybridization forming a\nhexagonal network and the hydrogen atoms are bonded to carbon on both sides of\nthe plane in an alternating manner. Graphane is predicted to be stable with a\nbinding energy comparable to other hydrocarbons such as benzene, cyclohexane,\nand polyethylene. We discuss possible routes for synthesizing graphane and\npotential applications as a hydrogen storage material and in two dimensional\nelectronics."
    },
    {
        "anchor": "Large Thermoelectric Power Factor in P-type Si (110)/[110]\n  Ultra-Thin-Layers Compared to Differently Oriented Channels: Using atomistic electronic structure calculations and Boltzmann\nsemi-classical transport we compute the thermoelectric power factor of\nultra-thin-body p-type Si layers of thicknesses from W=3nm up to 10nm. We show\nthat the power factor for channels in [110] transport orientation and strong\n(110) surface confinement largely outperforms all differently oriented channels\nby more than 2X. Furthermore, the power factor in this channel increases by\n~40% with layer thickness reduction. This increase, together with the large\nconfinement effective mass of the (110) surface, make this particular channel\nless affected by the detrimental effects of enhanced surface roughness\nscattering and distortion at the nanoscale. Our results, therefore, point\ntowards the optimal geometrical features regarding orientation and length scale\nfor power factor improvement in 2D thin-layers of zincblende semiconductors.",
        "positive": "Half metallic ferromagnetism in tri-layered perovskites\n  Sr$_4$T$_{3}$O$_{10}$ (T=Co, Rh): First-principles density functional theory (DFT) is used to investigate the\nelectronic and magnetic properties of Sr$_4$Rh$_3$O$_{10}$, a member of the\nRuddlesden-Popper series. Based on the DFT calculations taking into account the\nco-operative effect of Coulomb interaction ($U$) and spin-orbit couplings\n(SOC), Sr$_4$Rh$_3$O$_{10}$ is found to be a half metallic ferromagnet (HMF)\nwith total angular moment $\\mu_{\\rm {tot}}$=12$\\mu_B$ per unit cell. The\nmaterial has almost 100$\\%$ spin-polarization at the Fermi level despite of\nsizable SOC. Replacement of Rh atom by the isovalent Co atom is considered.\nUpon full-replacement of Co, a low-spin to intermediate spin transition happens\nresulting in a HMF state with the total angular moment three-time larger (i.e.\n$\\mu_{\\rm {tot}}$=36$\\mu_B$ per unit cell), compared to Sr$_4$Rh$_3$O$_{10}$.\nWe propose Sr$_4$Rh$_3$O$_{10}$ and Sr$_4$Co$_3$O$_{10}$ as candidates of half\nmetals."
    },
    {
        "anchor": "Unveiling the dopant segregation effect at hematite interfaces: Understanding the effects of atomic structure modification in hematite\nphotoanodes is essential for the rational design of high-efficiency\nfunctionalizations. Recently it was found that interface modification with\nSn/Sb segregates considerably increases hematite photocatalytic efficiency.\nHowever, the understanding of the different electronic effects of these\nmodifications at the atomic level is still lacking. This letter describes the\nsegregation effects of two different dopants-Sn and Sb-on both the solid-solid\n(grain-boundaries) and solid-liquid interfaces (surfaces) of hematite. Within\nan ab-initio approach, we quantitatively extract the potential barrier\nreduction on polycrystalline interfaces due to the dopant, which causes an\nincrease in the inter-grain electron transport. Concomitantly, the dopants'\nsegregation on hematite surfaces results in a decrease of the oxygen vacancy\nformation energy. Such vacancies lead to the experimentally observed rise of\nthe flat-band potential. The comprehension of the electronic effects of dopants\non both types of interfaces explains the experimental peak efficiency of\ninterface-modified hematite with dopant segregates, also enabling the control\nand design of interfaces for different higher-efficiency applications.",
        "positive": "Interlayer decoupling in twisted bilayers of $\u03b2$-phosphorus and\n  arsenic: a computational study: We investigate magnetism and band structure engineering in Moir\\'e\nsuperlattice of blue phosphorus ($\\beta$-P) and grey arsenene ($\\beta$-As)\nbilayers, using \\textit{ab initio} calculations. The electronic states near the\nvalence and conduction band edges have significant $p_z$ character in both the\nbilayers. Thus, twisting the layers significantly reduce the interlayer orbital\noverlap, leading to a decrease in the binding energy (up to $\\sim33\\%$) and an\nincrease in interlayer distance (up to $\\sim10\\%$), compared to the most stable\nAA-stacking. This interlayer decoupling also results in a notable increase (up\nto $\\sim$25-50\\%) of the bandgap of twisted bilayers, with the valance band\nedge becoming relatively flat with van-Hove singularities in the density of\nstates. Thus, hole doping induces a Stoner instability, leading to\nferromagnetic ground state, which is more robust in Moir\\'e superlattices, than\nthat of AA-stacked $\\beta$-P and $\\beta$-As."
    },
    {
        "anchor": "Topological nature of polarization and charge pumping in ferroelectrics: Electric polarization or transferred charge due to an adiabatic change of\nexternal parameters $\\vec{Q}$ is expressed in terms of a vector field defined\nin the $\\vec{Q}$ space. This vector field is characterized by strings, i.e.,\ntrajectories of band-crossing points. In particular, the transverse component\nis given by the Biot-Savart law in a nonlocal way. For a cyclic change of\n$\\vec{Q}$ along a loop C, the linking number between this string and C\nrepresents the amount of the pumped charge, which is quantized to be an integer\nas discussed by Thouless.",
        "positive": "Anomalous temperature-induced volume contraction in GeTe: The recent surge of interest in phase change materials GeTe,\nGe$_2$Sb$_2$Te$_5$, and related compounds motivated us to revisit the\nstructural phase transition in GeTe in more details than was done before.\nRhombohedral-to-cubic ferroelectric phase transition in GeTe has been studied\nby high resolution neutron powder diffraction on a spallation neutron source.\nWe determined the temperature dependence of the structural parameters in a wide\ntemperature range extending from 309 to 973 K. Results of our studies clearly\nshow an anomalous volume contraction of 0.6\\% at the phase transition from the\nrhombohedral to cubic phase. In order to better understand the phase transition\nand the associated anomalous volume decrease in GeTe we have performed phonon\ncalculations based on the density functional theory. Results of the present\ninvestigations are also discussed with respect to the experimental data\nobtained for single crystals of GeTe."
    },
    {
        "anchor": "Advanced materials for solid-state refrigeration: Recent progress on caloric effects are reviewed. The application of external\nstimuli such as magnetic field, hydrostatic pressure, uniaxial stress and\nelectric field give rise respectively to magnetocaloric, barocaloric,\nelastocaloric and electrocaloric effects. The values of the relevant quantities\nsuch as isothermal entropy and adiabatic temperature-changes are compiled for\nselected materials. Large values for these quantities are found when the\nmaterial is in the vicinity of a phase transition. Quite often there is\ncoupling between different degrees of freedom, and the material can exhibit\ncross-response to different external fields. In this case, the material can\nexhibit either conventional or inverse caloric effects when a field is applied.\nThe values reported for the many caloric effects at moderate fields are large\nenough to envisage future application of these materials in efficient and\nenvironmental friendly refrigeration.",
        "positive": "High-order crystal field and rare-earth magnetism in RECo5\n  intermetallics: Crystal-field (CF) effects on the rare-earth (RE) ions in ferrimagnetic\nintermetallics NdCo$_5$ and TbCo$_5$ are evaluated using an ab initio density\nfunctional + dynamical mean-field theory approach in conjunction with a\nquasi-atomic approximation for on-site electronic correlations on the localized\n4$f$ shell. The study reveals an important role of the high-order sectoral\nharmonic component of the CF in the magnetism of RECo$_5$ intermetallics. An\nunexpectedly large value is computed in the both systems for the corresponding\ncrystal-field parameter (CFP) $A_6^6 \\langle r^6 \\rangle$, far beyond what one\nwould expect from only electrostatic contributions. It allows solving the\nenigma of the non-saturation of zero-temperature Nd magnetic moments in\nNdCo$_5$ along its easy axis in the Co exchange field. This unsaturated state\nhad been previously found out from magnetization distribution probed by\npolarised neutron elastic scattering but had so far remained theoretically\nunexplained. The easy plane magnetic anisotropy of Nd in NdCo$_5$ is strongly\nenhanced by the large value of $A_6^6\\langle r^6 \\rangle$. Counter-intuitively,\nthe polar dependence of anisotropy energy within the easy plane remains rather\nsmall. The easy plane magnetic anisotropy of Nd is reinforced up to high\ntemperatures, which is explained through $J$-mixing effects. The calculated ab\ninitio anisotropy constants of NdCo$_5$ and their temperature dependence are in\nquantitative agreement with experiment. Unlike NdCo$_5$, the $A_6^6 \\langle r^6\n\\rangle$ CFP has negligible effects on the Tb magnetism in TbCo$_5$ suggesting\nthat its impact on the RE magnetism is ion-specific across the RECo$_5$ series.\nThe origin of its large value is the hybridization of RE and Co states in a\nhexagonally coordinated local environment of the RE ion in RECo$_5$\nintermetallics."
    },
    {
        "anchor": "Landau Theory of Tilting of Oxygen Octahedra in Perovskites: The list of possible commensurate phases obtained from the parent tetragonal\nphase of Ruddlesden-Popper systems, A$_{n+1}$B$_n$C$_{3n+1}$ for general $n$\ndue to a single phase transition involving the reorienting of octahedra of C\n(oxygen) ions is reexamined using a Landau expansion. This expansion allows for\nthe nonlinearity of the octahedral rotations and the rotation-strain coupling.\nIt is found that most structures allowed by symmetry are inconsistent with the\nconstraint of rigid octahedra which dictates the form of the quartic terms in\nthe Landau free energy. For A$_2$BC$_4$ our analysis allows only 10 (see Table\nIII) of the 41 structures listed by Hatch {\\it et al.} which are allowed by\ngeneral symmetry arguments. The symmetry of rotations for RP systems with $n>2$\nis clarified. Our list of possible structures in Table VII excludes many\nstructures allowed in previous studies.",
        "positive": "Quantum Hall Effect in Black Phosphorus Two-dimensional Electron Gas: Development of new, high quality functional materials has been at the\nforefront of condensed matter research. The recent advent of two-dimensional\nblack phosphorus has greatly enriched the material base of two-dimensional\nelectron systems. Significant progress has been made to achieve high mobility\nblack phosphorus two-dimensional electron gas (2DEG) since the development of\nthe first black phosphorus field-effect transistors (FETs)$^{1-4}$. Here, we\nreach a milestone in developing high quality black phosphorus 2DEG - the\nobservation of integer quantum Hall (QH) effect. We achieve high quality by\nembedding the black phosphorus 2DEG in a van der Waals heterostructure close to\na graphite back gate; the graphite gate screens the impurity potential in the\n2DEG, and brings the carrier Hall mobility up to 6000 $cm^{2}V^{-1}s^{-1}$. The\nexceptional mobility enabled us, for the first time, to observe QH effect, and\nto gain important information on the energetics of the spin-split Landau levels\nin black phosphorus. Our results set the stage for further study on quantum\ntransport and device application in the ultrahigh mobility regime."
    },
    {
        "anchor": "Artificial neural network molecular mechanics of iron grain boundaries: This study reports grain boundary (GB) energy calculations for 46\nsymmetric-tilt GBs in alpha-iron using molecular mechanics based on an\nartificial neural network (ANN) potential and compares the results with\ncalculations based on the density functional theory (DFT), the embedded atom\nmethod (EAM), and the modified EAM (MEAM). The results by the ANN potential are\nin excellent agreement with those of the DFT (5% on average), while the EAM and\nMEAM significantly differ from the DFT results (about 27% on average). In a\nuniaxial tensile calculation of Sigma 3 (1-12) GB, the ANN potential reproduced\nthe brittle fracture tendency of the GB observed in the DFT while the EAM and\nMEAM showed mistakenly showed ductile behaviors. These results demonstrate the\neffectiveness of the ANN potential in grain boundary calculations of iron as a\nfast and accurate simulation highly in demand in the modern industrial world.",
        "positive": "Compressed Crystalline Bismuth and Superconductivity-An ab initio\n  computational Simulation: Bismuth displays puzzling superconducting properties. In its crystalline\nequilibrium phase, it does not seem to superconduct at accessible low\ntemperatures. However, in the amorphous phase it displays superconductivity at\n~ 6 K. Under pressure bismuth has been found to superconduct at Tcs that go\nfrom 3.9 K to 8.5 K depending on the phase obtained. So the question is: what\nelectronic or vibrational changes occur that explains this radical\ntransformation in the conducting behavior of this material? In a recent\npublication we argue that changes in the density of electronic and vibrational\nstates may account for the behavior observed in the amorphous phase with\nrespect to the crystal. We have now undertaken an ab initio computational study\nof the effects of pressure alone maintaining the original crystalline structure\nand compressing our supercell computationally. From the results obtained we\ninfer that if the crystal structure remains the same (except for the\ncontraction), no superconductivity will appear."
    },
    {
        "anchor": "Photogating of mono- and few-layer MoS2: We describe a photogating effect in mono- and few-layer MoS2, which allows\nthe control of the charge carrier density by almost two orders of magnitude\nwithout electrical contacts. Our Raman studies are consistent with physisorbed\nenvironmental molecules, that effectively deplete the intrinsically n-doped\ncharge carrier system via charge transfer, and which can be gradually removed\nby the exposure to light. This photogating process is reversible and precisely\ntunable by the light intensity. The photogating efficiency is quantified by\ncomparison with measurements on electrostatically gated MoS2.",
        "positive": "In-Situ Monitoring of Thermal Annealing Induced Evolution in Film\n  Morphology and Film-Substrate Bonding in a Monolayer MoS2 Film: We perform in-situ two-cycle thermal cycling and annealing studies for a\ntransferred CVD-grown monolayer MoS2 on a SiO2/Si substrate, using spatially\nresolved micro-Raman and PL spectroscopy. After the thermal cycling and being\nannealed at 305 deg C twice, the film morphology and film-substrate bonding are\nsignificantly modified, which together with the removal of polymer residues\ncause major changes in the strain and doping distribution over the film, and\nthus the optical properties. Before annealing, the strain associated with\nripples in the transferred film dominates the spatial distributions of the PL\npeak position and intensity over the film; after annealing, the variation in\nfilm-substrate bonding, affecting both strain and doping, becomes the leading\nfactor. This work reveals that the film-substrate bonding, and thus the strain\nand doping, is unstable under thermal stress, which is important for\nunderstanding the substrate effects on the optical and transport properties of\nthe 2D material and their impact on device applications."
    },
    {
        "anchor": "Role of Site-selective Doping on Melting Point of CuTi Alloys: A\n  Classical Molecular Dynamics Simulation Study: Effect of site-selective substitution of Ti in Cu on the thermal stability of\nCuTi alloy is investigated using classical molecular dynamics simulations with\nEmbedded Atom Method potentials. It has been observed experimentally that\nmelting point of all the naturally occurring stable phases of CuTi alloys do\nnot show a definite trend with gradual increase in Ti concentration. To\nunderstand the phenomenon, super cells of CuTi alloy are constructed where Cu\natom is substituted by Ti randomly and at selective sites. For random\nsubstitution, the melting point decreases linearly with increase in Ti\nconcentration. A non-monotonous dependence is seen when Cu atoms at selective\nsites are replaced by Ti. For a particular doping concentration, the melting\npoint shows a wide range of variation depending on the order of atomic\narrangement, and can be fine tuned by selecting the sites for substitution. The\nvariations in melting points in different cases are explained in terms of the\npeak height, width and position of the corresponding radial distribution\nfunctions. Finally, it is verified that initial structures of the naturally\noccurring CuTi alloys are responsible for the non-definite trend in their\nmelting points.",
        "positive": "Electronic Excitations and Insulator-Metal Transition in\n  Poly(3-hexylthiophene) Organic Field-Effect Transistors: We carry out a comprehensive theoretical and experimental study of charge\ninjection in Poly(3-hexylthiophene) (P3HT) to determine the most likely\nscenario for metal-insulator transition in this system. We calculate the\noptical absorption frequencies corresponding to a polaron and a bipolaron\nlattice in P3HT. We also analyze the electronic excitations for three possible\nscenarios under which a first-- or a second--order metal--insulator transition\ncan occur in doped P3HT. These theoretical scenarios are compared with data\nfrom infrared absorption spectroscopy on P3HT thin film field-effect\ntransistors (FET). Our measurements and theoretical predictions suggest that\ncharge-induced localized states in P3HT FETs are bipolarons and that the\nhighest doping level achieved in our experiments approaches that required for a\nfirst-order metal--insulator transition."
    },
    {
        "anchor": "Evaluation of the \"disorder temperature\" and \"free volume\" formalisms\n  via simulations of shear banding in amorphous solids: Molecular dynamics simulations of shear band development over 1000% strain in\nsimple shear are used to test whether the local plastic strain rate is\nproportional to exp(-1/chi), where chi is a dimensionless quantity related to\nthe \"disorder temperature\" or \"free volume\" that characterizes the structural\nstate of the glass. Scaling is observed under the assumption that chi is\nlinearly related to the local potential energy per atom. This analysis permits\nthe extraction of the potential energy per atom at which chi=0 and the\napproximate energy needed to create a shear transformation zone.",
        "positive": "Amorphous ZrO2 from Ab-initio molecular dynamics: Structural, electronic\n  and dielectric properties: Realistic models of amorphous ZrO2 are generated in a ``melt-and-quench''\nfashion using ab-initio molecular dynamics in a plane-wave pseudopotential\nformulation of density-functional theory. The structural properties of the\nresulting amorphous models are analyzed, with special attention to coordination\nstatistics. The vibrational and dielectric properties of one of these models\nare then investigated from first principles using linear-response methods. The\nelectronic dielectric constant and Born effective charges are found to be very\nsimilar to those of the crystalline phases. Encouragingly, the predicted total\nstatic dielectric constant is about 22, comparable to that of the monoclinic\nphase. This work is motivated by the search for improved gate dielectric\nmaterials for sub-0.1 micron CMOS technology, and may also have implications\nfor HfO2 and for silicates of ZrO2 and HfO2."
    },
    {
        "anchor": "Polycrystal model of the mechanical behavior of a Mo-TiC30vol.%\n  metal-ceramic composite using a 3D microstructure map obtained by a dual beam\n  FIB-SEM: The mechanical behavior of a Mo-TiC30 vol.% ceramic-metal composite was\ninvestigated over a large temperature range (25^{\\circ}C to 700^{\\circ}C).\nHigh-energy X-ray tomography was used to reveal the percolation of the hard\ntitanium carbide phase through the composite. Using a polycrystal approach for\na two-phase material, finite element simulations were performed on a real 3D\naggregate of the material. The 3D microstructure, used as starting\nconfiguration for the predictions, was obtained by serial-sectioning in a dual\nbeam Focused Ion Beam (FIB)-Scanning Electron Microscope (SEM) coupled to an\nElectron Back Scattering Diffraction system (3D EBSD, EBSD tomography). The 3D\naggregate consists of a molybdenum matrix and a percolating TiC skeleton. As\nmost BCC metals, the molybdenum matrix phase is characterized by a change in\nthe plasticity mechanisms with temperature. We used a polycrystal model for the\nBCC material, which was extended to two phases (TiC and Mo). The model\nparameters of the matrix were determined from experiments on pure molydenum.\nFor all temperatures investigated, the TiC particles were considered as\nbrittle. Gradual damage of the TiC particles was treated, based on an\naccumulative failure law that is approximated by an evolution of the apparent\nparticle elastic stiffness. The model enabled us to determine the evolution of\nthe local mechanical fields with deformation and temperature. We showed that a\n3D aggregate representing the actual microstructure of the composite is\nrequired to understand the local and global mechanical properties of the\nstudied composite.",
        "positive": "Boron-Doped Graphene As Active Electrocatalyst For Oxygen Reduction\n  Reaction At A Fuel-Cell Cathode: Boron-doped graphene was reported to be the best non-metal doped graphene\nelectrocatalyst for the oxygen reduction reaction (ORR) working at an onset\npotential of 0.035 V [JACS 136 (2014) 4394]. In the present DFT study,\nintermediates and transition structures along the possible reaction pathways\nare determined. Both Langmuir-Hinschelwood and Eley-Rideal mechanisms are\ndiscussed. Molecular oxygen binds the positively charged B atom and forms an\nopen shell end-on dioxygen intermediate. The associative path is favoured with\nrespect to the dissociative one. The free energy diagrams along the\nfour-reduction steps are investigated with the methodology by N{\\o}rskov and\nco. [JPC B 108 (2004) 17886] in both acidic and alkaline conditions. The pH\neffect on the stability of the intermediates of reduction is analyzed in terms\nof the Pourbaix diagram. At pH = 14 we compute an onset potential value for the\nelectrochemical ORR of U = 0.05 V, which compares very well with the\nexperimental value in alkaline conditions."
    },
    {
        "anchor": "On the Formation of Solid States Beyond Perfect Crystals: Quasicrystals,\n  Geometrically-Frustrated Crystals and Glasses: There are three kinds of solid states of matter that can exist in physical\nspace: quasicrystalline (quasiperiodic), crystalline (periodic) and amorphous\n(aperiodic). Herein, we consider the degree of orientational order that\ndevelops upon the formation of a solid state to be characterized by the\napplication of quaternion numbers. The formation of icosahedral\nquasicrystalline solids is considered alongside the development of bulk\nsuperfluidity, characterized by a complex order parameter, that occurs by\nspontaneous symmetry breaking in three-dimensions. Crystalline solid states are\nviewed as higher-dimensional analogues to phase-coherent topologically-ordered\nsuperfluid states of matter that develop in restricted dimensions\n(Hohenberg-Mermin- Wagner theorem). Lastly, amorphous solid states are viewed\nas dual to crystalline solids, in analogy to Mott-insulating states of matter\nthat are dual to topologically-ordered superfluids.",
        "positive": "Angle-resolved polarized Raman spectroscopy for distinguishing stage-I\n  graphite intercalation compounds with Thorium, Uranium and Plutonium: Graphite intercalation compounds (GICs) with the geometrical anisotropy and\nstrong electron-phonon coupling are in full swing and have shown their great\npotential for applications in nanodevices. I selected representative three\nelements in actinide group with valence electron arrangement: Thorium (Th)\n([Rn]6d27s2), Uranium (U) ([Rn]5f36d17s2), Plutonium (Pu) ([Rn]5f67s2). I\ncalculated their phonon spectra and demonstrated the atomic-scale\nmicrostructure identification of actinide graphite intercalation compounds by\nangle-resolved polarized Raman spectroscopy."
    },
    {
        "anchor": "Deterministic generation of skyrmions and antiskyrmions by electric\n  current: Magnetic skyrmions are nanoscale spin whirlpools that promise breakthroughs\nin future spintronic applications. Controlled generation of magnetic skyrmions\nby electric current is crucial for this purpose. While previous studies have\ndemonstrated this operation, the topological charge of the generated skyrmions\nis determined by the direction of the external magnetic fields, thus is fixed.\nHere, we report the current-induced skyrmions creation in a chiral magnet FeGe\nnanostructure by using the \\emph{in-situ} Lorentz transmission electron\nmicroscopy. We show that magnetic skyrmions or antiskyrmions can be both\ntransferred from the magnetic helical ground state simply by controlling the\ndirection of the current flow at zero magnetic field. The force analysis and\nsymmetry consideration, backed up by micromagnetic simulations, well explain\nthe experimental results, where magnetic skyrmions or antiskyrmions are created\ndue to the edge instability of the helical state in the presence of spin\ntransfer torque. The on-demand generation of skyrmions and control of their\ntopology by electric current without the need of magnetic field will enable\nnovel purely electric-controlled skyrmion devices.",
        "positive": "Extending solid-state calculations to ultra long-range length scales: We present a method which enables solid-state density functional theory\ncalculations to be applied to systems of almost unlimited size. Computations of\nphysical effects up to the micron length scale but which nevertheless depend on\nthe microscopic details of the electronic structure, are made possible. Our\napproach is based on a generalization of the Bloch state which involves an\nadditional sum over a finer grid in reciprocal space around each ${\\bf\nk}$-point. We show that this allows for modulations in the density and\nmagnetization of arbitrary length on top of a lattice-periodic solution. Based\non this, we derive a set of ultra long-range Kohn-Sham equations. We\ndemonstrate our method with a sample calculation of bulk LiF subjected to an\narbitrary external potential containing nearly 3500 atoms. We also confirm the\naccuracy of the method by comparing the spin density wave state of bcc Cr\nagainst a direct supercell calculation starting from a random magnetization\ndensity. Furthermore, the spin spiral state of $\\gamma$-Fe is correctly\nreproduced and the screening by the density of a saw-tooth potential over 20\nunit cells of silicon is verified."
    },
    {
        "anchor": "Theoretical Study of Extrinsic Spin-current Generation in Ferromagnets\n  Induced by Anisotropic Spin-flip Scattering: The spin Hall effect (SHE) and the magnetic spin Hall effect (MSHE) are\nresponsible for electrical spin current generation, which is a key concept of\nmodern spintronics. We theoretically investigated the spin conductivity induced\nby spin-dependent s-d scattering in a ferromagnetic 3d alloy model by employing\nmicroscopic transport theory based on the Kubo formula. We derived a novel\nextrinsic mechanism that contributes to both the SHE and MSHE. This mechanism\ncan be understood as the contribution from anisotropic (spatial-dependent)\nspin-flip scattering due to the combination of the orbital-dependent\nanisotropic shape of s-d hybridization and spin flipping, with the orbital\nshift caused by spin-orbit interaction with the d-orbitals. We also show that\nthis mechanism is valid under crystal-field splitting among the d-orbitals in\neither the cubic or tetragonal symmetry.",
        "positive": "Towards two-dimensional metallic behavior at LaAlO3/SrTiO3 interfaces: Using a low-temperature conductive-tip atomic force microscope in\ncross-section geometry we have characterized the local transport properties of\nthe metallic electron gas that forms at the interface between LaAlO3 and\nSrTiO3. At low temperature, we find that the carriers do not spread away from\nthe interface but are confined within ~10 nm, just like at room temperature.\nSimulations taking into account both the large temperature and electric-field\ndependence of the permittivity of SrTiO3 predict a confinement over a few nm\nfor sheet carrier densities larger than ~6 10^13 cm-2. We discuss the\nexperimental and simulations results in terms of a multi-band carrier system.\nRemarkably, the Fermi wavelength estimated from Hall measurements is ~16 nm,\nindicating that the electron gas in on the verge of two-dimensionality."
    },
    {
        "anchor": "Rotationally invariant formulation of spin-lattice coupling in\n  multi-scale modeling: In the spirit of multi-scale modeling, we develop a theoretical framework for\nspin-lattice coupling that connects, on the one hand, to ab initio calculations\nof spin-lattice coupling parameters and, on the other hand, to the\nmagneto-elastic continuum theory. The derived Hamiltonian describes a closed\nsystem of spin and lattice degrees of freedom and explicitly conserves the\ntotal momentum, angular momentum and energy. Using a new numerical\nimplementation that corrects earlier Suzuki-Trotter decompositions we perform\nsimulations on the basis of the resulting equations of motion to investigate\nthe combined magnetic and mechanical motion of a ferromagnetic nanoparticle,\nthereby validating our developed method. In addition to the ferromagnetic\nresonance mode of the spin system we find another low-frequency mechanical\nresponse and a rotation of the particle according to the Einstein-de-Haas\neffect. The framework developed herein will enable the use of multi-scale\nmodeling for investigating and understanding a broad range of\nmagneto-mechanical phenomena from slow to ultrafast time scales.",
        "positive": "Spin-transfer-driven ferromagnetic resonance of individual nanomagnets: We demonstrate a technique that enables ferromagnetic resonance (FMR)\nmeasurements of the normal modes for magnetic excitations in individual\nnanoscale ferromagnets, smaller in volume by a factor of 1000 than can be\nprobed by other methods. The measured peak shapes indicate two regimes of\nresponse: simple FMR and phase locking. Studies of the resonance frequencies,\namplitudes, and linewidths as a function of microwave power, DC current, and\nmagnetic field provide detailed new information about the exchange, damping,\nand spin-transfer torques that govern the dynamics in magnetic nanostructures."
    },
    {
        "anchor": "Non-equilibrium spin dynamics in the temperature and magnetic field\n  dependence of magnetization curves of ferrimagnetic\n  Co$_{1.75}$Fe$_{1.25}$O$_4$ and its composite with BaTiO$_3$: A comparative study of the non-equilibrium magnetic phenomena (magnetic\nblocking, memory, exchange bias and aging effect) has been presented for\nferrimagnetic Co$_{1.75}$Fe$_{1.25}$O$_4$ (CFO) and its composite with\nnon-magnetic BaTiO$_3$ (BTO). Synchrotron X-Ray diffraction patterns have\nconfirmed coexistence of CFO and BTO structures in composite, but magnetic spin\ndynamics have been remarkably modified. The blocking phenomenon of\nferrimagnetic domains below the room temperature has been studied by different\nmodes of (zero field cooled and field cooled) magnetic measurements in\ncollaboration with magnetic fields ON and OFF modes and time dependent\nmagnetization. The applications of unconventional protocols during time\ndependent magnetization measurement at different stages of the temperature and\nfield dependence of the magnetization curves have been useful to reveal the\nnon-equilibrium dynamics of magnetic spin order. The applying of off-field\nrelaxation experiments has made possible to tune the magnetic state and\ncoercivity of the systems. The role of interfacial coupling between magnetic\nand non-magnetic particles has been understood on different magnetic phenomena\n(meta-stable magnetic state, exchange bias and memory effect) by comparing the\nexperimental results of Co$_{1.75}$Fe$_{1.25}$O$_4$ spinel oxide and its\ncomposite with BaTiO$_3$ particles.",
        "positive": "Understanding the catalyst-free transformation of amorphous carbon into\n  graphene by current-induced annealing: We shed light on the catalyst-free growth of graphene from amorphous carbon\n(a-C) by current-induced annealing by witnessing the mechanism both with\nin-situ transmission electron microscopy and with molecular dynamics\nsimulations. Both in experiment and in simulation, we observe that small a-C\nclusters on top of a graphene substrate rearrange and crystallize into graphene\npatches. The process is aided by the high temperatures involved and by the van\nder Waals interactions with the substrate. Furthermore, in the presence of a-C,\ngraphene can grow from the borders of holes and form a seamless graphene sheet,\na novel finding that has not been reported before and that is reproduced by the\nsimulations as well. These findings open up new avenues for bottom-up\nengineering of graphene-based devices."
    },
    {
        "anchor": "Degradation of Phosphorene in Air: Understanding at Atomic Level: Phosphorene is a promising two dimensional (2D) material with a direct band\ngap, high carrier mobility, and anisotropic electronic properties.\nPhosphorene-based electronic devices, however, are found to degrade upon\nexposure to air. In this paper, we provide an atomic level understanding of\nstability of phosphorene in terms of its interaction with O2 and H2O. The\nresults based on density functional theory together with first principles\nmolecular dynamics calculations show that O2 could spontaneously dissociate on\nphosphorene at room temperature. H2O will not strongly interact with pristine\nphosphorene, however, an exothermic reaction could occur if phosphorene is\nfirst oxidized. The pathway of oxidation first followed by exothermic reaction\nwith water is the most likely route for the chemical degradation of the\nphosphorene-based devices in air.",
        "positive": "Magnetocapacitive La0.6Sr0.4MnO3 0.7Pb(Mg0.33Nb0.67)O3 0.3PbTiO3\n  epitaxial heterostructures: Epitaxial heterostructures of La0.6Sr0.4MnO3 0.7Pb(Mg0.33Nb0.67)O3 0.3PbTiO3\nwere fabricated on LaNiO3 coated LaAlO3 (100) substrates by pulsed laser\nablation. Ferromagnetic and ferroelectric hysteresis established their\nbiferroic nature. Dielectric behviour studied under different magnetic fields\nover a wide range of frequency and temperatures revealed that the capacitance\nin these heterostructures varies with the applied magnetic field. Appearance of\nmagnetocapacitance and its dependence on magnetic fields, magnetic layer\nthickness, temperature and frequency indicated a combined contribution of\nstrain mediated magnetoelectric coupling, magnetoresistance of the magnetic\nlayer and Maxwell Wagner effect on the observed properties."
    },
    {
        "anchor": "Tuning Interfacial Ferromagnetism in LaNiO$_3$/CaMnO$_3$ Superlattices\n  by Stabilizing Non-Equilibrium Crystal Symmetry: Perovskite oxide heterostructures offer an important path forward for\nstabilizing and controlling low-dimensional magnetism. One of the guiding\ndesign principles for these materials systems is octahedral connectivity. In\nsuperlattices composed of perovskites with different crystal symmetries,\nvariation of the relative ratio of the constituent layers as well as the\nindividual layer thicknesses gives rise to non-equilibrium crystal symmetries\nthat, in turn, lead to unprecedented control of interfacial ferromagnetism. We\nhave found that in superlattices of CaMnO$_3$ (CMO) and LaNiO$_3$ (LNO),\ninterfacial ferromagnetism can be modulated by a factor of three depending on\nLNO and CMO layer thicknesses as well as their relative ratio. Such an effect\nis only possible due to the non-equilibrium crystal symmetries at the\ninterfaces and can be understood in terms of the anisotropy of the exchange\ninteractions and modifications in the interfacial Ni-O-Mn and Mn-O-Mn bond\nangles and lengths with increasing LNO layer thickness. These results\ndemonstrate the potential of engineering non-equilibrium crystal symmetries in\ndesigning ferromagnetism.",
        "positive": "Negative thermal expansion in ZnF$_2$: We have investigated temperature dependence of the lattice parameters and the\nunit cell volume of ZnF$_2$ by neutron diffraction and have discovered negative\nthermal expansion (NTE) at low temperature. To understand why this simple\ncompound exhibits NTE we performed first principle calculations. These\ncalculations reproduce qualitatively the experimental temperature dependence of\nvolume."
    },
    {
        "anchor": "Ab initio framework for deciphering trade-off relationships in\n  multi-component alloys: While first-principles methods have been successfully applied to characterize\nindividual properties of multi-principal element alloys (MPEA), their use to\nsearch for optimal trade-offs between competing properties is hampered by high\ncomputational demands. In this work, we present a novel framework to explore\nPareto-optimal compositions by integrating advanced ab-initio-based techniques\ninto a Bayesian multi-objective optimization method. We benchmark the framework\nby applying it to solid solution strengthening and ductility of refractory\nMPEAs, with the parameters of the strengthening and ductility models being\nefficiently computed using a combination of the coherent-potential\napproximation method, accounting for finite-temperature effects, and\nactively-learned moment-tensor potentials parameterized with ab initio data.\nAdditionally, we introduce an analytical model that captures the concentration\ndependence of all relevant material properties, relying on a few\nelement-specific parameters and universal functions that describe bonding\nbetween elements. Our findings offer new crucial insights into the traditional\nstrength-vs-ductility dilemma of refractory MPEAs. The proposed framework is\nversatile and can be extended to other materials and properties of interest,\nenabling a predictive and tractable high-throughput screening of Pareto-optimal\nMPEAs over the entire composition space.",
        "positive": "Bulk transport properties of Bismuth selenide thin films approaching the\n  two-dimensional limit: We have investigated the transport properties of topological insulator Bi2Se3\nthin films grown using magnetron sputtering with an emphasis on understanding\nthe behavior as a function of thickness. We show that thickness has a strong\ninfluence on all aspects of transport as the two-dimensional limit is\napproached. Bulk resistivity and Hall mobility show disproportionately large\nchanges below 6 quintuple layer which we directly correlate to an increase in\nthe bulk band gap of few-layer Bi2Se3, an effect that is concomitant with\nsurface gap opening. A tendency to crossover from a metallic to an insulating\nbehavior in temperature-dependent resistivity measurements in ultra-thin Bi2Se3\nis also consistent with an increase in the bulk band gap along with enhanced\ndisorder at the film-substrate interface. Our work highlights that the\nproperties of few-layer Bi2Se3 are tunable that may be attractive for a variety\nof device applications in areas such as optoelectronics, nanoelectronics and\nspintronics."
    },
    {
        "anchor": "Water oxidation catalysis on reconstructed NaTaO$_3$ (001) surfaces: Polar perovskite oxide surfaces are subject to structural reconstruction as a\npossible stabilisation mechanisms, which changes the surface structure and\nhence the surface chemistry. To investigate this effect, we study the oxygen\nevolution reaction (OER) on the reconstructed (001) surface of NaTaO$_3$, by\nmeans of density functional theory (DFT) calculations and compare it with the\nnon-polar (113) surface of the same material. For the clean surface the\nreconstruction has a beneficial effect on the catalytic activity, lowering the\nminimal overpotential from 0.88 V to 0.70 V while also changing the most active\nreaction site from Na to Ta. Under photocatalytic conditions, the Ta sites are\ncovered by oxygen adsorbates, rendering a lattice oxygen site on the NaO\nterrace the most active with a very low overpotential of 0.32 V. An alternative\nsurface reconstruction stable in contact with water leads to an oxygen coupling\nmechanism with an overpotential of 0.52 V. Our results show that terraced\nsurface reconstructions enable novel reaction pathways with low overpotentials\nthat do not exist on other non-polar NaTaO$_3$ surfaces nor on non-polar\nsurfaces of chemically similar materials such as SrTaO$_2$N.",
        "positive": "Combined Thermal Expansion and Hydrolytic Stability Study of Lanthanide\n  Vanadates LnVO4 and CaLnZr(VO4)3 (Ln = La, Nd, Sm, Eu, Gd, Dy, Yb) with\n  Zircon and Monazite Structures: The paper presents the investigation of ordinary and ternary vanadates with\nzircon and monazite structures. Vanadates LnVO4 and CaLnZr(VO4)3 , where (Ln =\nLa, Nd, Sm, Eu, Gd, Dy, Yb) and solid solution La0.3Nd0.5Sm0.1Eu0.1VO4, were\nprepared by precipitation reaction. Bulk ceramic samples were obtained from\npowders by Spark Plasma Sintering (SPS). The powders and ceramics were examined\nwith several physicochemical methods. The coefficients of thermal expansion at\n900{\\deg}C were determined. The hydrolytic stability of ceramic materials was\nstudied. The peculiarities of high-rate SPS of powders of ordinary and ternary\nvanadates were analyzed."
    },
    {
        "anchor": "Direct current plasma spraying of mechanofused alumina-steel particles: Stainless steel particles (60 $\\mu$m in mean diameter) cladded with an\nalumina shell (2 $\\mu$m thick and manufactured by mechanofusion) were sprayed\nwith an Ar-H2 (53-7 slm) d.c. plasma jet (I = 500 A, P = 28 kW, \\rho_th = 56\n%). Two main types of particles were collected in flight, as close as 50 mm\ndownstream of the nozzle exit: particles with a steel core with pieces of\nalumina unevenly distributed at their surface and those consisting of a\nspherical stainless steel particle with an alumina cap. The plasma flow was\nmodeled by a 2D steady parabolic model and a single particle trajectory by\nusing the 3D Boussinesq-Oseen-Basset equation. The heat transfer, within the\ntwo-layer, stainless steel cladded by alumina, particle, considered the heat\npropagation phenomena including phase changes. The models allowed determining\nthe positions, along the particle trajectory, where the convective movement\ncould occur as well as the entrainment of the liquid oxide to the leading edge\nof the in-flight particles. The heat transfer calculations showed the\nimportance of the thermal contact resistance TCR between alumina and steel.",
        "positive": "How much can donor/acceptor-substitution change the responses of long\n  push-pull systems to DC fields?: Mathematical arguments are presented that give a unique answer to the\nquestion in the title. Subsequently, the mathematical analysis is extended\nusing results of detailed model calculations that, in addition, throw further\nlight on the consequences of the analysis. Finally, through a comparison with\nvarious recent studies, many of the latter are given a new interpretation."
    },
    {
        "anchor": "Frustrated couplings between alternating spin-1/2 chains in AgVOAsO4: We report on the crystal structure and magnetic behavior of the spin-1/2\ncompound AgVOAsO4. Magnetic susceptibility, high-field magnetization, and\nelectron spin resonance measurements identify AgVOAsO4 as a gapped quantum\nmagnet with a spin gap Delta ~ 13 K and a saturation field H_s ~ 48.5 T.\nExtensive band structure calculations establish the microscopic magnetic model\nof spin chains with alternating exchange couplings J ~ 40 K and J' ~ 26 K.\nHowever, the precise evaluation of the spin gap emphasizes the role of\ninterchain couplings which are frustrated due to the peculiar crystal structure\nof the compound. The unusual spin model and the low energy scale of the\nexchange couplings make AgVOAsO4 a promising candidate for an experimental\ninvestigation of Bose-Einstein condensation and other exotic ground states in\nhigh magnetic fields.",
        "positive": "Rupture of amorphous graphene via void formation: Apart from its unique and exciting electronic properties, many sensor based\napplications of graphene are purely based on its mechanical and structural\nproperties. Here we report a numerical and analytical study of a void in\namorphous (small domain polycrystalline) graphene, and show that the energetics\nof a void is a balance between the line tension cost versus the increased area\ngain. Using the concepts of classical nucleation theory, we show that the\ncritical radius of a void formed in amorphous graphene at constant pressure is\nsimply the ratio of line tension at the void and the applied pressure. The\nvalues of the critical radius of the void for flat and buckled graphene are\n3.48\\AA ~and 3.31\\AA, respectively at 2 eV/\\AA${^2}$ pressure. We also show\nthat the dominant finite size correction to the line tension is inversely\nproportional to the radius of the void in both flat and buckled cases. Contrary\nto conventional wisdom, with the help of a simple analytical model we find that\nthe shear modulus sets the lower limit of the line tension in the samples. This\nmakes our study relevant for other two-dimensional amorphous materials such as\nh-BN, phosphorene, borophene, and transition metal dichalcogenides. Our results\nare useful for the better understanding of polycrystalline graphene under\ntension and therefore have direct implications on the very fascinating field of\nstrain engineering known as \"straintronics\" to manipulate or improve graphene's\nproperties."
    },
    {
        "anchor": "Predicted Realization of Cubic Dirac Fermion in Quasi-One-Dimensional\n  Transition-Metal MonoChalcogenides: We show that the previously predicted Fermion particle that has no analogue\nin the standard model of particle theory - the cubically dispersed Dirac\nsemimetal (CDSM) - is realized in a specific, stable solid state system that\nhas been made years ago, but was not appreciated to host such a unique Fermion,\ncomposed of six Weyl Fermions, 3 with left-handed and 3 with right-handed\nchirality. We identified the crystal symmetry constraints and found the space\ngroup P63/m as one of the two that can support a CDSM, of which the\ncharacteristic band crossing has linear dispersion along the principle axis but\ncubic dispersion in the plane perpendicular to it. We then conducted a material\nsearch using density functional theory identifying a group of\nquasi-one-dimensional molybdenum mono-chalcogenide compounds A(MoX)3 (A = Na,\nK, Rb, In, Tl, X = S, Se, Te) as ideal CDSM candidates. Studying the stability\nof the A(MoX)3 family reveals a few candidates such as Rb(MoTe)3 and Tl(MoTe)3\nthat are predicted to be resilient to Peierls distortion, thus retaining the\nmetallic character. The combination of one-dimensionality and metallic nature\nin this family provides a platform for unusual optical signature - polarization\ndependent metallic vs insulating response.",
        "positive": "Attosecond dispersive soft X-ray absorption fine structure spectroscopy\n  in graphite: Phase transitions of solids and structural transformations of molecules are\ncanonical examples of important photo-induced processes, whose underlying\nmechanisms largely elude our comprehension due to our inability to correlate\nelectronic excitation with atomic position in real time. Here, we present a\ndecisive step towards such new methodology based on water-window-covering (284\neV to 543 eV) attosecond soft X-ray pulses that can simultaneously access\nelectronic and lattice parameters via dispersive X-ray absorption\nfine-structure (XAFS) spectroscopy. We validate attoXAFS with an identification\nof the {\\sigma}* and {\\pi}* orbital contributions to the density of states in\ngraphite simultaneously with its lattice's four characteristic bonding\ndistances. This work demonstrates the concept of attoXAFS as a powerful\nreal-time investigative tool which is equally applicable to gas-, liquid- and\ncondensed phase."
    },
    {
        "anchor": "Silicon-based spin and charge quantum computation: Silicon-based quantum-computer architectures have attracted attention because\nof their promise for scalability and their potential for synergetically\nutilizing the available resources associated with the existing Si technology\ninfrastructure. Electronic and nuclear spins of shallow donors (e.g.\nphosphorus) in Si are ideal candidates for qubits in such proposals due to the\nrelatively long spin coherence times. For these spin qubits, donor electron\ncharge manipulation by external gates is a key ingredient for control and\nread-out of single-qubit operations, while shallow donor exchange gates are\nfrequently invoked to perform two-qubit operations. More recently, charge\nqubits based on tunnel coupling in P$_2^+$ substitutional molecular ions in Si\nhave also been proposed. We discuss the feasibility of the building blocks\ninvolved in shallow donor quantum computation in silicon, taking into account\nthe peculiarities of silicon electronic structure, in particular the six\ndegenerate states at the conduction band edge. We show that quantum\ninterference among these states does not significantly affect operations\ninvolving a single donor, but leads to fast oscillations in electron exchange\ncoupling and on tunnel-coupling strength when the donor pair relative position\nis changed on a lattice-parameter scale. These studies illustrate the\nconsiderable potential as well as the tremendous challenges posed by donor spin\nand charge as candidates for qubits in silicon.",
        "positive": "The Effect of Electrode Size on Memristor Properties: An Experimental\n  and Theoretical Study: The width of the electrodes is not included in the current phenomenological\nmodels of memristance, but is included in the memory-conservation (mem-con)\ntheory of memristance. An experimental study of the effect of changing the top\nelectrode width was performed on titanium dioxide sol-gel memristors. It was\ndemonstrated that both the on resistance, Ron, and the off resistance, Roff,\ndecreased with increasing electrode size. The memory function part of the\nmem-con model could fit the relationship between Ron and electrode size.\nSimilarly, the conservation function fits the change in Roff. The\nexperimentally measured hysteresis did not fit the phenomenological model's\npredictions. Instead the size of the hysteresis increased with increasing\nelectrode size, and correlated well to decreasing Ron."
    },
    {
        "anchor": "Topologically protected interface phonons in two-dimensional\n  nanomaterials: hexagonal boron nitride and silicon carbide: We perform both lattice dynamics analysis and molecular dynamics simulations\nto demonstrate the existence of topologically protected phonon modes in a\ntwo-dimensional, monolayer hexagonal boron nitride sheet. The topological\nphonon modes are found to be localized at an in-plane interface that divides\nthe system into two regions of distinct valley Chern numbers. The dispersion of\nthis topological phonon mode crosses over the frequency gap [1123, 1278]\ncm^{-1}, which is opened through analogy with the quantum valley Hall effect by\nbreaking inversion symmetry of the boron and nitride atoms in the primitive\nunit cell. Consequently, vibrational energy with frequency within this gap is\ntopologically protected, resulting in wave propagation that exhibits minimal\nbackscattering, is robust with regards to structural defects such as sharp\ncorners, and exhibits excellent temporal stability. Our findings open up the\npossibility of realizing topological phonons and mechanics in two-dimensional\nnanomaterials.",
        "positive": "Selective Gas Sensing with a Single Pristine Graphene Transistor: We show that vapors of different chemicals produce distinguishably different\neffects on the low-frequency noise spectra of graphene. It was found in a\nsystematic study that some gases change the electrical resistance of graphene\ndevices without changing their low-frequency noise spectra while other gases\nmodify the noise spectra by inducing Lorentzian components with distinctive\nfeatures. The characteristic frequency fc of the Lorentzian noise bulges in\ngraphene devices is different for different chemicals and varies from fc=10 -\n20 Hz to fc=1300 - 1600 Hz for tetrahydrofuran and chloroform vapors,\nrespectively. The obtained results indicate that the low-frequency noise in\ncombination with other sensing parameters can allow one to achieve the\nselective gas sensing with a single pristine graphene transistor. Our method of\ngas sensing with graphene does not require graphene surface functionalization\nor fabrication of an array of the devices with each tuned to a certain\nchemical."
    },
    {
        "anchor": "Metamaterials: $\\textit{supra}$-classical dynamic homogenization: Metamaterials are artificial composite structures designed for controlling\nwaves or fields, and exhibit interaction phenomena that are unexpected on the\nbasis of their chemical constituents. These phenomena are encoded in effective\nmaterial parameters that can be electronic, magnetic, acoustic, or elastic, and\nmust adequately represent the wave interaction behaviour in the composite\nwithin desired frequency ranges. In some cases -- for example, the low\nfrequency regime -- there exist various efficient ways by which effective\nmaterial parameters for wave propagation in metamaterials may be found.\nHowever, the general problem of predicting frequency-dependent dynamic\neffective constants has remained unsolved. Here, we obtain novel mathematical\nexpressions for the effective parameters of two-dimensional metamaterial\nsystems valid at higher frequencies and wavelengths than previously possible.\nBy way of an example, random configurations of cylindrical scatterers are\nconsidered, in various physical contexts: sound waves in a compressible fluid,\nanti-plane elastic waves, and electromagnetic waves. Our results point towards\na paradigm shift in our understanding of these effective properties, and\nmetamaterial designs with functionalities beyond the low-frequency regime are\nnow open for innovation.",
        "positive": "Thin-film effects on the surface stopping power of a free electron gas: The electronic properties of thin films present quantum-size effects, which\nare a consequence of the finite size of the system. Here we focus on the\ninvestigation of these effects on the electronic energy loss of charged\nparticles moving parallel with thin metallic films. The energy loss is\ncalculated, within linear-response theory, from the knowledge of the\ndensity-response function of the inhomogeneous electron system, which we\nevaluate either in the random-phase approximation or with the use of an\nadiabatic and local exchange-correlation kernel."
    },
    {
        "anchor": "Intrinsic origin of the two-dimensional electron gas at polar oxide\n  interfaces: The predictions of the polar catastrophe scenario to explain the occurrence\nof a metallic interface in heterostructures of the solid\nsolution(LaAlO$_3$)$_{x}$(SrTiO$_3$)$_{1-x}$ (LASTO:x) grown on (001) SrTiO$_3$\nwere investigated as a function of film thickness and $x$. The films are\ninsulating for the thinnest layers, but above a critical thickness, $t_c$, the\ninterface exhibits a constant finite conductivity which depends in a\npredictable manner on $x$. It is shown that $t_c$ scales with the strength of\nthe built-in electric field of the polar material, and is immediately\nunderstandable in terms of an electronic reconstruction at the nonpolar-polar\ninterface. These results thus conclusively identify the polar-catastrophe model\nas the intrinsic origin of the doping at this polar oxide interface.",
        "positive": "Nonreciprocal Second-Harmonic Generation in Few-Layer Chromium Triiodide: It is of fundamental importance but challenging to simultaneously identify\natomic and magnetic configurations of two-dimensional van der Waals materials.\nIn this work, we show that the nonreciprocal second-harmonic generation (SHG)\ncan be a powerful tool to answer this challenge. Despite the preserved lattice\ninversion symmetry, the interlayer antiferromagnetic order and spin-orbit\ncoupling generate enhanced SHG in PT-symmetric bilayer chromium triiodide\n(CrI3). Importantly, the in-plane polarization-resolved SHG is sensitive to\nsubtly different interlayer structures that cannot be told by linear optical\nspectra. Beyond bilayer, we further predict that the intensity and\nangle-resolved SHG can be employed to identify both interlayer atomic and\nmagnetic configurations of trilayer CrI3. Our first-principles results agree\nwith available measurements and show the potential of SHG as a non-contacting\napproach to explore correlations between interlayer structures and magnetic\norders of emerging ultra-thin magnetic materials."
    },
    {
        "anchor": "Quantification and Mapping of Elastic Strains Ferroelectric\n  BaZrO3/BaTiO3 Superlattices: We report on quantification and elastic strain mapping in two artificial\nBaZrO3/BaTiO3 (BZ/BT) superlattices having periods of 6.6 nm and 11 nm\nrespectively, grown on (001) SrTiO3 single crystal substrate by pulsed laser\ndeposition technique. The methodology consists of a combination of\nhigh-resolution scanning transmission electron microscopy and nanobeam electron\ndiffraction associated with dedicated algorithm for diffraction patterns\nprocessing originally developed for semiconductors to record the strains at\natomic scale. Both in-plane and out-of-plane elastic strains were then\ndetermined at 2 nm spatial resolution and their average values were used to map\nthe strains along and transverse to the epitaxial growth direction of both\nsamples to determine its variation along several BZ/BT interfaces. In addition,\nthe variation of the width of the inter-diffusion BT/BZ interfaces and\nintermixing between different layers are estimated. The obtained width average\nvalue measured in these inter-diffusion interfaces vary from 8 to 12% and from\n9 to 11% for both superlattices having period of 6.6 nm and 11 nm respectively.\nThese inter-diffusion interfaces and the inherent elastic strains due to the\nconfined layers of the superlattices are known to be the most important\nparameters, responsible of the change in their functional properties.",
        "positive": "Elastic Strain Associated with Irradiation-Induced Defects in Self-ion\n  Irradiated Tungsten: Elastic interactions play an important role in controlling irradiation damage\nevolution, but remain largely unexplored experimentally. Using transmission\nelectron microscopy (TEM) and high-resolution on-axis transmission Kikuchi\ndiffraction (HR-TKD), we correlate the evolution of irradiation-induced damage\nstructures and the associated lattice strains in self-ion irradiated pure\ntungsten. TEM reveals different dislocation loop structures as a function of\nsample thickness, suggesting that free surfaces limit the formation of extended\ndefect structures found in thicker samples. HR-TKD strain analysis shows the\nformation of crystallographically-orientated long-range strain fluctuation\nabove 0.01 dpa and a decrease of total elastic energy above 0.1 dpa."
    },
    {
        "anchor": "High-pressure synthesis of boron-rich chalcogenides B12S and B12Se: Two boron-rich chalcogenides B12S and B12Se isostructural to\n{\\alpha}-rhombohedral boron were synthesized by chemical reaction of the\nelements at high-pressure - high-temperature conditions. The crystal structures\nand stoichiometries of both compounds were confirmed by Rietveld refinement and\nelemental analysis. The experimental Raman spectra of B12S and B12Se were\ninvestigated for the first time. All observed Raman bands have been attributed\nto the theoretically calculated phonon modes, and the mode assignment has been\nperformed.",
        "positive": "Ultra-fast synthesis and thermodynamic analysis of MoAlB by\n  self-propagating high temperature combustion synthesis: MoAlB as a typical member of the MAB phases has attracted much growing\nattention due to its unique properties. However, the low production of MoAlB\npowders limits its further development and potential applications. To respond\nthis challenge, the ultra-fast preparation of high-purity MoAlB powders is\nachieved in a few seconds by self-propagating high temperature combustion\nsynthesis (SHS) using the raw powder mixture at the atomic ratio of\n1Mo/1.3Al/1B. The reaction mechanism in SHS process was obtained by analyzing\nthe corresponding composition changes of starting materials. Furthermore, the\nthermodynamic prediction for the SHS reaction of Mo + (1+y)Al + B = MoAlB + yAl\nis consistent with the present experiments, where the preparation of MoAlB also\nconforms to two common self-propagating conditions of SHS. Enthalpy vs\ntemperature curve shows that the adiabatic temperature of the reaction\ndecreases with increasing the amount of excuse Al, but increase when\npre-heating the reactants. The thermodynamic calculation method also provides a\nnew idea for the preparation of other MAB phases by SHS."
    },
    {
        "anchor": "Cm2 Scale Synthesis of MoTe2 Thin Films with Large Grains and Layer\n  Control David: Owing to the small energy differences between its polymorphs, MoTe2 can\naccess a full spectrum of electronic states, from the 2H semiconducting state\nto the 1T semimetallic state, and from the Td Weyl semimetallic state to the\nsuperconducting state in the 1T and Td phase at low temperature. Thus, it is a\nmodel system for phase transformation studies as well as quantum phenomena such\nas the quantum spin Hall effect and topological superconductivity. Careful\nstudies of MoTe2 and its potential applications require large area MoTe2 thin\nfilms with high crystallinity and thickness control. Here, we present cm2 scale\nsynthesis of 2H MoTe2 thin films with layer control and large grains that span\nseveral microns. Layer control is achieved by controlling the initial thickness\nof the precursor MoOx thin films, which are deposited on sapphire substrates by\natomic layer deposition and subsequently tellurized. Despite the van der Waals\nepitaxy, the precursor-substrate interface is found to critically determine the\nuniformity in thickness and grain size of the resulting MoTe2 films: MoTe2\ngrown on sapphire show uniform films while MoTe2 grown on amorphous SiO2\nsubstrates form islands. This synthesis strategy decouples the layer control\nfrom the variabilities of growth conditions for robust growth results, and is\napplicable to grow other transition metal dichalcogenides with layer control.",
        "positive": "Elastic and electronic properties of hexagonal rhenium sub-nitrides Re3N\n  and Re2N in comparison with hcp-Re and wurtzite-like rhenium mononitride ReN: Very recently, two new hexagonal rhenium sub-nitrides Re3N and Re2N, which\nbelong to a rather rare group of known metal-rich (M/N > 1) nitrides of heavy\n4d,5d metals, have been successfully synthesized, and their potential\ntechnological applications as ultra-incompressible materials have been\nproposed. In this work we present a detailed ab initio study of novel rhenium\nsub-nitrides in comparison with hcp-Re and wurtzite-like rhenium mono-nitride\nReN, with the purpose to evaluate the trends of the elastic, electronic\nproperties and chemical bonding in the series of these hexagonal systems as a\nfunction of the Re/N stoichiometry: Re \\rightarrow Re3N \\rightarrow Re2N\n\\rightarrow ReN."
    },
    {
        "anchor": "Substrate Effects on the Speed Limiting Factor of WSe$_2$ Photodetectors: We investigate the time-resolved photoelectric response of WSe$_2$ crystals\non common glass and flexible polyimide substrates to determine the effect of\nthe dielectric environment on the speed of the photodetectors. We show that\nvarying the substrate material can alter the speed-limiting mechanism: while\nthe detectors on polyimide are RC limited, those on glass are limited by slower\nexcitonic diffusion processes. We attribute this to a shortening of the\ndepletion layer at the metal electrode/WSe2 interface caused by the higher\ndielectric screening of glass compared to polyimide. The photodetectors on\nglass show a tunable bandwidth which can be increased to 2.6 MHz with\nincreasing the electric field.",
        "positive": "DensityTool: A post-processing tool for space- and spin-resolved density\n  of states from VASP: The knowledge of the local electronic structure of heterogeneous solid\nmaterials is crucial for understanding their electronic, magnetic, transport,\noptical, and other properties. VASP, one of the mostly used packages for\ndensity-functional calculations, provides local electronic structure either by\nprojecting the electronic wave functions on atomic spheres, or as a\nband-decomposed partial charge density. Here, we present a simple tool which\ntakes the partial charge density and the energy eigenvalues calculated by VASP\nas input and constructs local charge and spin densities. The new data provides\na much better spatial resolution than the projection on the atomic spheres. It\ncan be visualized directly in the real space e.g. with Vesta, or averaged along\nplanes spanned by two of the lattice vectors of the periodic unit cell. The\nplane-averaged local (spin) density of states can be easily plotted e.g. as\ncolor-coded data using almost any plotting program. DensityTool can be applied\nto manipulate, visualize, and understand the local electronic structure of any\nsystem calculated with VASP. We expect it to be useful especially for\nresearchers concerned with inhomogeneous systems, such as interfaces, defects,\nsurfaces, adsorbed molecules, or hybrid inorganic-organic composites."
    },
    {
        "anchor": "The influence of dynamical change of optical properties on the\n  thermomechanical response and damage threshold of noble metals under\n  femtosecond laser irradiation: We present a theoretical investigation of the dynamics of the dielectric\nconstant of noble metals following heating with ultrashort pulsed laser beams\nand the influence of the temporal variation of the associated optical\nproperties in the thermomechanical response of the material. The effect of the\nelectron relaxation time on the optical properties based on the use of a\ncritical point model is thoroughly explored for various pulse duration values\n(i.e. from 110fs to 8ps). The proposed theoretical framework correlates the\ndynamical change of optical parameters, relaxation processes and induced\nstrains-stresses. Simulations are presented by choosing gold as a test material\nand we demonstrate that the consideration of the aforementioned factors leads\nto significant thermal effect changes compared to results when static\nparameters are assumed. The proposed model predicts a substantially smaller\ndamage threshold and a large increase of the stress which firstly underlines\nthe significant role of the temporal variation of the optical properties and\nsecondly enhances its importance with respect to the precise determination of\nlaser specifications in material micromachining techniques.",
        "positive": "H2 Mapping on Pt-loaded TiO2 Nanotube Gradient Arrays: We describe a rapid screening technique for determining the optimal\ncharacteristics of nano- photocatalysts for the production of H2 on a single\nsurface. Arrays of TiO2 nanotubes (NTs) with a gradient in length and diameter\nwere fabricated by bipolar anodization and a perpendicular gradient of Pt\nnanoparticles (NPs) was generated by the toposelective decoration of the TiO2\nNTs. Photocatalytic hydrogen evolution was locally triggered with a UV laser\nbeam and the arrays were screened in x- and y-direction for spatially resolved\nkinetic measurements and the mapping of the optimal hydrogen production. By\nusing this technique, we demonstrate the time-efficient and straightforward\ndetermination of the tube dimensions and the Pt amount for an optimized H2\nproduction. The concept holds promise to generally improve the study of many\nphotoreactions as a function of the physicochemical characteristic of\nnano-photocatalysts, which renders it highly attractive for the optimization of\nvarious important chemical processes."
    },
    {
        "anchor": "Magnetically driven ferroelectric order in Ni$_3$V$_2$O$_8$: We show that for Ni$_3$V$_2$O$_8$ long-range ferroelectric and incommensurate\nmagnetic order appear simultaneously in a single phase transition. The\ntemperature and magnetic field dependence of the spontaneous polarization show\na strong coupling between magnetic and ferroelectric orders. We determine the\nmagnetic symmetry of this system by constraining the data to be consistent with\nLandau theory for continuous phase transitions. This phenomenological theory\nexplains our observation the spontaneous polarization is restricted to lie\nalong the crystal b axis and predicts that the magnitude should be proportional\nto a magnetic order parameter.",
        "positive": "Energetics and kinetics of vacancies in monolayer graphene boron nitride\n  heterostructures: Graphene and boron nitride (GPBN) heterostructures provide a viable way to\nrealize tunable bandgap, promising new opportunities in graphene-based\nnanoelectronic and optoelectronic devices. In the present study, we\ninvestigated the interplay between vacancies and graphene/h-BN interfaces in\nmonolayer GPBN heterostructures. The energetics and kinetics of monovacancies\nand divacancies in monolayer GPBN heterostructures were examined using\nfirst-principle calculations. The interfaces were shown to be preferential\nlocations for vacancy segregation. Meanwhile the kinetics of vacancies was\nfound to be noticeably modified at interfaces, evidenced by the Minimum Energy\nPaths (MEPs) and associated migration barriers calculations. The role of\ninterfacial bonding configurations, energy states and polarization on the\nformation and diffusion of vacancies were discussed. Additionally we\ndemonstrated that it is important to recognize the dissimilarities in the\ndiffusion prefactor for different vacancies for accurate determination of the\nvacancy diffusion coefficient. Our results provide essential data for the\nmodeling of vacancies in GPBN heterostructures, and important insights towards\nthe precise engineering of defects, interfaces and quantum domains in the\ndesign of GPBN-based devices."
    },
    {
        "anchor": "All-Optical Materials Design of Chiral Edge Modes in Transition-Metal\n  Dichalcogenides: Manipulating materials properties far from equilibrium recently garnered\nsignificant attention, with experimental emphasis on transient melting,\nenhancement, or induction of electronic order. A more tantalizing aspect of the\nmatter-light interaction regards the possibility to access dynamical steady\nstates with distinct non-equilibrium phase transitions to affect electronic\ntransport. Here, we show that the interplay of crystal symmetry and optical\npumping of monolayer transition-metal dichalcogenides (TMDCs) provides a novel\navenue to engineer topologically-protected chiral edge modes. In stark contrast\nto graphene and previously-discussed toy models, the underlying generic\nmechanism relies on the intrinsic three-band nature of TMDCs near the band\nedges. Photo-induced band inversions scale linearly in applied pump field and\nexhibit a transition from one to two chiral edge modes upon sweeping from red\nto blue detuning. We develop a strategy to understand non-equilibrium\nFloquet-Bloch bands and topological transitions directly from ab initio\ncalculations, and illustrate for the example of WS$_2$ that control of chiral\nedge modes can be dictated solely from symmetry principles and is not\nqualitatively sensitive to microscopic materials details.",
        "positive": "Point defect avalanches mediate grain boundary diffusion: Grain boundary (GB) diffusion in polycrystalline materials is a physical\nphenomenon of great fundamental interest and practical significance. Although\nthe accelerated (\"short circuit\") atomic transport along GBs has been known for\ndecades, the current atomic-level understanding of GB diffusion remains poor.\nExperiments can measure numerical values of GB diffusion coefficients but\nprovide little information about the underlying mechanisms. Previous atomistic\nsimulations focused on relatively low temperatures when the GB structure is\nordered or relatively high temperatures when it is highly disordered. Here, we\nreport on molecular dynamics simulations of GB diffusion at intermediate\ntemperatures, which are most relevant to applications. One of the surprising\nresults of this work is the observation of strongly intermittent GB diffusion\nbehavior and its strong system-size dependence unseen in previous work. We\ndemonstrate that both effects originate from an intermittent, avalanche-type\ngeneration of point defects causing spontaneous bursts of GB diffusivity\nmediated by highly cooperative atomic rearrangements. We identify the length\nand time scales of the avalanches and link their formation to the dynamic\nheterogeneity phenomenon in partially disordered systems. Our findings have\nsignificant implications for future computer modeling of GB diffusion and mass\ntransport in nano-scale materials."
    },
    {
        "anchor": "Third Harmonics and Defects in Modulated Phases of Structural Quantum\n  Order-Disorder Systems: Influences of defects generating random fields on modulated phases in\nmaterials with the order-disorder type of phase transition are studied. It is\nshown that under appropriate conditions third harmonics of the ground state\nmodulation may be suppressed by these defects.",
        "positive": "Formation of localized hole states in complex oxides: Defect electrons (holes) play an important role in most technologically\nimportant complex oxides; many of which possess perovskite-related structures.\nIn this contribution we present the first detailed characterization of\nlocalized hole states in such materials. Our investigations employ advanced\nembedded-cluster calculations which consistently include electron correlations\nand defect-induced lattice relaxations. This is necessary in order to account\nfor the variety of possible hole-state manifestations."
    },
    {
        "anchor": "Efficient thermal energy harvesting using nanoscale magnetoelectric\n  heterostructures: Thermomechanical cycles with a ferroelectric working substance convert heat\nto electrical energy. As shown here, magnetoelectrically coupled\nferroelectric/ferromangtic composites (also called multiferroics) add new\nfunctionalities and allow for an efficient thermal energy harvesting at room\ntemperature by exploiting the pyroelectric effect. By virtue of the\nmagnetoelectric coupling, external electric and magnetic fields can steer the\noperation of these heat engines. Our theoretical predictions are based on a\ncombination of Landau-Khalatnikov-Tani approach (with a\nGinzburg-Landau-Devonshire potential) to simulate the ferroelectric dynamics\ncoupled to the magnetic dynamics. The latter is treated via the\nelectric-polarization-dependent Landau-Lifshitz-Gilbert equation. Performing an\nadapted Olsen cycle we show that a multiferroic working substance is\npotentially much more superior to sole ferroelectrics, as far as thermal energy\nharvesting using pyroelectric effect is concerned. Our proposal holds promise\nnot only for low-energy consuming devices but also for cooling technology.",
        "positive": "Graphene resonator as an ultrasound detector for generalized Love waves\n  in a polymer film with two level states: We have investigated surface shear waves at 22 MHz in a 0.5-micron-thick\npolymer film on SiO2/Si substrate at low temperatures using suspended and\nnon-suspended graphene as detectors. By tracking ultrasound modes detected by\noscillations of a trilayer graphene membrane both in vacuum and in helium\nsuperfluid, we assign the resonances to surface shear modes, generalized Love\nwaves, in the resist/silicon-substrate system loaded with gold. The propagation\nvelocity of these shear modes displays a logarithmic temperature dependence\nbelow 1 K, which is characteristic for modification of the elastic properties\nof a disordered solid owing to a large density of two level state (TLS)\nsystems. For the dissipation of the shear mode, we find a striking logarithmic\ntemperature dependence, which indicates a basic relation between the speed of\nthe surface wave propagation and the mode dissipation."
    },
    {
        "anchor": "Lifetime of skyrmions in discrete systems with infinitesimal lattice\n  constant: Topological protection of chiral magnetic structures is investigated by\ntaking a two-dimensional magnetic skyrmion as an example. The skyrmion lifetime\nis calculated based on harmonic transition state theory for a discrete lattice\nmodel using various values of the ratio of the lattice constant and the\nskyrmion size. Parameters of the system corresponding to exchange, anisotropy\nand Dzyaloshinsky-Moriya interaction are chosen in such a way as to keep the\nenergy and size of the skyrmion unchanged for small values of the lattice\nconstant, using scaling relations derived from continuous micromagnetic\ndescription. The number of magnetic moments included in the calculations\nreaches more than a million. The results indicate that in the limit of\ninfinitesimal lattice constant, the energy barrier for skyrmion collapse\napproaches the Belavin-Polyakov lower bound of the energy of a topological\nsoliton in the $\\sigma$-model, the entropy contribution to the pre-exponential\nfactor in the Arrhenius rate expression for collapse approaches a constant and\nthe skyrmion lifetime can, for large enough number of spins, correspond to\nthermally stable skyrmion at room temperature even without magnetic\ndipole-dipole interaction.",
        "positive": "Energy loss of charged particles moving parallel to a magnesium surface: We present it ab initio calculations of the electronic energy loss of charged\nparticles moving outside a magnesium surface, from a realistic description of\nthe one-electron band structure and a full treatment of the dynamical\nelectronic response of valence electrons. Our results indicate that the finite\nwidth of the plasmon resonance, which is mainly due to the presence of\nband-structure effects, strongly modifies the asymptotic behaviour of the\nenergy loss at large distances from the surface. This effect is relevant for\nthe understanding of the interaction between charged particles and the internal\nsurface of microcapillaries."
    },
    {
        "anchor": "Magnetoelectric effects of nanoparticulate Pb(Zr0.52Ti0.48)O3-NiFe2O4\n  composite films: We fabricated Pb(Zr0.52Ti0.48)O3-NiFe2O4 composite films consisting of\nrandomly dispersed NiFe2O4 nanoparticles in the Pb(Zr0.52Ti0.48)O3 matrix. The\nstructural analysis revealed that the crystal axes of the NiFe2O4 nanoparticles\nare aligned with those of the ferroelectric matrix. The composite has good\nferroelectric and magnetic properties. We measured the transverse and\nlongitudinal components of the magnetoelectric voltage coefficient, which\nsupports the postulate that the magnetoelectric effect comes from direct stress\ncoupling between magnetostrictive NiFe2O4 and piezoelectric Pb(Zr0.52Ti0.48)O3\ngrains.",
        "positive": "A repulsive skyrmion chain as guiding track for a race track memory: A skyrmion racetrack design is proposed that allows for thermally stable\nskyrmions to code information and dynamical pinning sites that move with the\napplied current. This concept solves the problem of intrinsic distributions of\npinning times and pinning currents of skyrmions at static geometrical or\nmagnetic pinning sites. The dynamical pinning sites are realized by a skyrmion\ncarrying wire, where the skyrmion repulsion is used in order to keep the\nskyrmions at equal distances. The information is coded by an additional layer\nwhere the presence and absence of a skyrmion is used to code the information.\nThe lowest energy barrier for a data loss is calculated to be DE = 55 kBT300\nwhich is sufficient for long time thermal stability."
    },
    {
        "anchor": "Structural and electronic properties of the incommensurate host-guest\n  Bi-III phase: At high pressure, bismuth acquires a complex incommensurate host-guest\nstructure, only recently discovered. Characterizing the structure and\nproperties of this incommensurate phase from first principles is challenging\nowing to its non-periodic nature. In this study we use large scale DFT\ncalculations to model commensurate approximants to the Bi-III phase, and in\nparticular to describe the atomic modulations with respect to their ideal\npositions, shown here to strongly affect the electronic structure of the\nlattice and its stability. The equation of state and range of stability of\nBi-III are reproduced in excellent agreement with experiment using a fully\nrelativistic model. We demonstrate the importance of employing large unit-cells\nfor the accurate description of the geometric and electronic configuration of\nBi-III. In contrast, accurate description of the equation of state of bismuth\nis found to be primarily sensitive to the choice of pseudopotential and\nexchange-correlation function, while almost completely insensitive to the\ncommensurate approximation.",
        "positive": "Adatoms in graphene as a source of current polarization: Role of the\n  local magnetic moment: We theoretically investigate spin-resolved currents flowing in large-area\ngraphene, with and without defects, doped with single atoms of noble metals\n(Cu, Ag and Au) and 3d-transition metals (Mn,Fe,Co and Ni). We show that the\npresence of a local magnetic moment is a necessary but not sufficient condition\nto have a non zero current polarization. An essential requirement is the\npresence of spin-split localized levels near the Fermi energy that strongly\nhybridize with the graphene pi-bands. We also show that a gate potential can be\nused to tune the energy of these localized levels, leading to an external way\nto control the degree of spin-polarized current without the application of a\nmagnetic field."
    },
    {
        "anchor": "Atomistic simulations of the implantation of low energy boron and\n  nitrogen ions into graphene: By combining classical molecular dynamics simulations and density functional\ntheory total energy calculations, we study the possibility of doping graphene\nwith B/N atoms using low-energy ion irradiation. Our simulations show that the\noptimum irradiation energy is 50 eV with substitution probabilities of 55% for\nN and 40% for B. We further estimate probabilities for different defect\nconfigurations to appear under B/N ion irradiation. We analyze the processes\nresponsible for defect production and report an effective swift chemical\nsputtering mechanism for N irradiation at low energies (~125 eV) which leads to\nproduction of single vacancies. Our results show that ion irradiation is a\npromising method for creating hybrid C-B/N structures for future applications\nin the realm of nanoelectronics.",
        "positive": "Complex order-parameter phase-field models derived from structural\n  phase-field-crystal models: The phase-field-crystal (PFC) modeling paradigm is rapidly emerging as the\nmodel of choice when investigating materials phenomena with atomistic scale\neffects over diffusive time scales. Recent variants of the PFC model, so-called\nstructural PFC (XPFC) models introduced by Greenwood et al., have further\nincreased the capability of the method by allowing for easy access to various\nstructural transformations in pure materials [Phys. Rev. Lett. 105, 045702\n(2010)] and binary alloys [Phys. Rev. B. 84, 064104, (2011)]. We present an\namplitude expansion of these XPFC models, leading to a mesoscale complex\norder-parameter (amplitude), i.e., phase-field representation, model for two\ndimensional square-triangular structures. Amplitude models retain the salient\natomic scale features of the underlying PFC models, while resolving\nmicrostructures on mesoscales as in traditional phase-field models. The\napplicability and capability of this complex amplitude model is demonstrated\nwith simulations of peritectic solidification and grain growth exhibiting the\nemergence of secondary phase structures."
    },
    {
        "anchor": "Superlinear density dependence of singlet fission rate in tetracene\n  films: We experimentally show that the rate of singlet fission in tetracene films\nhas a superlinear dependence on the density of photo-excited singlet excitons\nwith ultrafast transient absorption spectroscopy. The spectrotemporal features\nof singlet and triplet dynamics can be disentangled from experimental data with\nthe algorithm of singular value decomposition. The correlation between their\ntemporal dynamics indicates a nonlinear density dependence of fission rate,\nwhich leads to a conjecture of coherent singlet fission process arising from\nsuperradiant excitons in crystalline tetracene. This hypothesis might be able\nto resolve some long-standing controversies.",
        "positive": "Space Group Symmetry of BaFe$_2$Se$_3$: ab initio-Experiment Phonon\n  Study: This paper presents a study of the structure dynamics in BaFe$_2$Se$_3$. We\ncombined first-principle calculations, infrared measurements and a thorough\nsymmetry analysis. Our study confirms that $Pnma$ cannot be the space group of\nBaFe$_2$Se$_3$, even at room temperature. The phonons assignment requires $Pm$\nto be the BaFe$_2$Se$_3$ space group, not only in the magnetic phase, but also\nin the paramagnetic phase at room temperature. This is due to a strong coupling\nbetween a short range spin-order along the ladders, and the lattice degrees of\nfreedom associated with the Fe-Fe bond length. This coupling induces a change\nin the bond-length pattern from an alternated trapezoidal one (as in $Pnma$) to\nan alternated small/large rectangular one. Out of the two patterns, only the\nlatter is fully compatible with the observed block-type magnetic structure.\nFinally, we propose a complete symmetry analysis of the BaFe$_2$Se$_3$ phase\ndiagram in the 0-600\\,K range."
    },
    {
        "anchor": "Reversible Switching of Charge Injection Barriers at\n  Metal/Organic-Semiconductor Contacts Modified with Structurally Disordered\n  Molecular Monolayers: Metal/semiconductor interfaces govern the operation of semiconductor devices\nthrough the formation of charge injection barriers that can be controlled by\ntuning the metal work function. However, the controlling ability is typically\nlimited to being static. We show that a dynamic nature can be imparted to the\ninterfaces using electrode surface modification with a structurally disordered\nmolecular monolayer. The barrier height at the interfaces is altered\nsignificantly in a reversible way by an external electric field. As a result, a\ndramatic change in the carrier transport properties through the interfaces is\nobserved, such as a reversible polarity reversion of\nmetal/organic-semiconductor/metal diodes.",
        "positive": "Structure, Dynamics and Themodynamics of a metal chiral surface: Cu(532): The structure, vibrational dynamics and thermodynamics of a chiral surface,\nCu(532), has been calculated using a local approach and the harmonic\napproximation, with interatomic potentials based on the embedded atom method.\nThe relaxation of atomic positions to the optimum configuration results in a\ncomplex relaxation pattern with strong contractions in the bond length of atoms\nnear the kink and the step site and an equivalently large expansion near the\nleast under-coordinated surface atoms. The low coordination of the atoms on the\nsurface affects substantially the vibrational dynamics and thermodynamics of\nthis system. The local vibrational density of states show a deviation from the\nbulk behavior that persist down to the 10th layer resulting in a substantial\ncontribution of the vibrational entropy to the excess free energy amounting to\nabout 90 meV per unit cell at 300K."
    },
    {
        "anchor": "Time-Reversal-Breaking Weyl Fermions in Magnetic Heusler Alloys: Weyl fermions have recently been observed in several time-reversal-invariant\nsemimetals and photonics materials with broken inversion symmetry. These\nsystems are expected to have exotic transport properties such as the chiral\nanomaly. However, most discovered Weyl materials possess a substantial number\nof Weyl nodes close to the Fermi level that give rise to complicated transport\nproperties. Here we predict, for the first time, a new family of Weyl systems\ndefined by broken time-reversal symmetry, namely, Co-based magnetic Heusler\nmaterials XCo2Z (X = IVB or VB; Z = IVA or IIIA). To search for Weyl fermions\nin the centrosymmetric magnetic systems, we recall an easy and practical\ninversion invariant, which has been calculated to be -1, guaranteeing the\nexistence of an odd number of pairs of Weyl fermions. These materials exhibit,\nwhen alloyed, only two Weyl nodes at the Fermi level - the minimum number\npossible in a condensed matter system. The Weyl nodes are protected by the\nrotational symmetry along the magnetic axis and separated by a large distance\n(of order 2$\\pi$) in the Brillouin zone. The corresponding Fermi arcs have been\ncalculated as well. This discovery provides a realistic and promising platform\nfor manipulating and studying the magnetic Weyl physics in experiments.",
        "positive": "On-Surface Synthesis of Heptacene on Ag(001) from Brominated and\n  Non-Brominated Tetrahydroheptacene Precursors: Achieving the Ag(001)-supported synthesis of heptacene from two related\nreactants reveals the effect of the presence of Br atoms on the reaction\nprocess. The properties of reactant, intermediates and end-product are further\ncharacterized by scanning tunneling microscopy and spectroscopy."
    },
    {
        "anchor": "Elucidating the barriers on direct water splitting: Key role of oxygen\n  vacancy density and coordination over PbTiO$_3$ and TiO$_2$: In this work, using the state-of-the-art first principles calculations based\non density functional theory, we found that the concentration as well as\ncoordination of surface oxygen vacancies with respect to each other were\ncritical for direct water-splitting reaction on the (001) surfaces of PbTiO$_3$\nand TiO$_2$. For the water-splitting reaction to happen on TiO$_2$-terminated\nsurfaces, it is necessary to have two neighboring O-vacancies acting as active\nsites that host two adsorbing water molecules. However, eventual dissociation\nof O-H bonds is possible only in the presence of an additional nearest-neighbor\nO-vacancy. Unfortunately, this necessary third vacancy inhibits the formation\nof molecular hydrogen by trapping the dissociated H atoms over\nTiO$_2$-teminated surfaces. Formation of up to 3 O-vacancies, is energetically\nless costly on both terminations of PbTiO$_3$ (001) surfaces compared with that\nof TiO$_2$, the presence of Pb leads to weaker O bonds over these surfaces.\nMolecular hydrogen formation is more favorable over the PbO-terminated surface\nof PbTiO$_3$, requiring only two neighboring oxygen vacancies. However,\nhydrogen molecule is retained near the surface by weak van der Waals forces.\nOur study indicates two barriers leading to low productivity of direct water\nsplitting processes. First and foremost, there is an entropic barrier imposed\nby the requirement of at least two nearest-neighbor O-vacancies, sterically\nhindering the process. Furthermore, there are also enthalpic barriers of\nformation over TiO$_2$-terminated surfaces, or removal of H$_2$ molecules from\nthe PbO-terminated surface.",
        "positive": "Thermal Transport in Graphene, Few-Layer Graphene and Graphene\n  Nanoribbons: The discovery of unusual heat conduction properties of graphene has led to a\nsurge of theoretical and experimental studies of phonon transport in\ntwo-dimensional material systems. The rapidly developing graphene thermal field\nspans from theoretical physics to practical engineering applications. In this\ninvited review we outline different theoretical approaches developed for\ndescribing phonon transport in graphene and provide comparison with available\nexperimental thermal conductivity data. A special attention is given to\nanalysis of the recent theoretical results for the phonon thermal conductivity\nof graphene and few-layer graphene, the effects of the strain, defects,\nisotopes and edge scattering on the acoustic phonon transport in these material\nsystems."
    },
    {
        "anchor": "Evolution of electronic band reconstruction in thickness-controlled\n  perovskite SrRuO$_3$ thin films: Transition metal perovskite oxides display a variety of emergent phenomena\nwhich are tunable by tailoring the oxygen octahedral rotation. SrRuO$_3$, a\nferromagnetic perovskite oxide, is well-known to have various atomic structures\nand octahedral rotations when grown as thin films. However, how the electronic\nstructure changes with the film thickness has been hardly studied. Here, by\nusing angle-resolved photoemission spectroscopy and electron diffraction\ntechniques, we study the electronic structure of SrRuO$_3$ thin films as a\nfunction of the film thickness. Different reconstructed electronic structures\nand spectral weights are observed for films with various thicknesses. We\nsuggest that octahedral rotations on the surface can be qualitatively estimated\nvia comparison of intensities of different bands. Our observation and\nmethodology shed light on how structural variation and transition may be\nunderstood in terms of photoemission spectroscopy data.",
        "positive": "Machine learning the band gap properties of kesterite I$_2$-II-IV-V$_4$\n  quaternary compounds for photovoltaics applications: Kesterite I$_2$-II-IV-V$_4$ semiconductors are promising solar absorbers for\nphotovoltaics applications. The band gap and it's character, either direct or\nindirect, are fundamental properties determining photovoltaic-device\nefficiency. We use a combination of accurate first-principles calculations and\nmachine learning to predict the properties of the band gap for a large number\nof kesterite I$_2$-II-IV-V$_4$ semiconductors. In determining the magnitude of\nthe fundamental gap, we compare results for a number of machine-learning\nmodels, and achieve a root mean squared error as low as 283 meV; the best\nresults are achieved using support-vector regression with a radial-bias kernel.\nThis error is well within the uncertainty of even the most advanced\nfirst-principles methods for calculating semiconductor band gaps. Predicting\nthe direct--indirect property of the band gap is more challenging. After\nsignificant feature engineering, we are able to train a classifier that\npredicts the nature of the band gap with an accuracy of 89 \\% using logistic\nregression. Using these trained models, the band gap properties of 1568\nkesterite I$_2$-II-IV-V$_4$ compounds are predicted. We find 717 compounds with\nband gaps in the range 0.5 -- 2.5 eV that can potentially act as solar\nabsorbers, and 242 materials with a band gap in the ``\\emph{optimum range}\" of\n1.2 -- 1.8 eV. The stability of these 242 compounds is assessed by calculating\nthe Energy Above Hull using the Materials Project database, and the band gaps\nare verified using hybrid functional calculations; in the end, we identify 25\ncompounds that are expected to be synthesizable, and have a band gap in the\nrange 1.2 -- 1.8 eV -- most of which are previously unexplored. These results\nwill be useful in the materials engineering of efficient photovoltaic devices."
    },
    {
        "anchor": "Possible coupling between magnons and phonons in multiferroic CaMn7O12: Spin and lattice dynamics of CaMn7O12 ceramics were investigated using\ninfrared, THz and inelastic neutron scattering (INS) spectroscopies in the\ntemperature range 2 to 590 K, and, at low temperatures, in applied magnetic\nfields of up to 12 T. On cooling, we observed phonon splitting accompanying the\nstructural phase transition at Tc = 450K as well as the onset of the\nincommensurately modulated structure at 250 K. In the two antiferromagnetic\nphases below T_N1 = 90K and T_N2 = 48 K, several infrared-active excitations\nemerge in the meV range; their frequencies correspond to the maxima in the\nmagnon density of states obtained by INS. At the magnetic phase transitions,\nthese modes display strong anomalies and for some of them, a transfer of\ndielectric strength from the higher-frequency phonons is observed. We propose\nthat these modes are electromagnons. Remarkably, at least two of these modes\nremain active also in the paramagnetic phase; for this reason, we call them\nparaelectromagnons. In accordance with this observation, quasielastic neutron\nscattering revealed short-range magnetic correlations persisting within\ntemperatures up to 500K above T_N1.",
        "positive": "H4-Alkanes: A new class of hydrogen storage material?: The methane-based material (H$_2$)$_4$CH$_4$, also called H4M for short, is\nin essence a methane molecule with 4 physisorbed H$_2$ molecules. While H4M has\nexceptionally high hydrogen storage densities when it forms a molecular solid,\nunfortunately, this solid is only stable at impractically high pressures and/or\nlow temperatures. To overcome this limitation, we show through simulations that\nlonger alkanes (methane is the shortest alkane) also form stable structures\nthat still physisorb 4 H$_2$ molecules per carbon atom; we call those\nstructures H4-alkanes. We further show via molecular dynamics simulations that\nthe stability field of molecular solids formed from H4-alkanes increases\nremarkably with chain length compared to H4M, just as it does for regular\nalkanes. From our simulations of H4-alkanes with lengths 1, 4, 10, and 20, we\nsee that e.g. for the 20-carbon the stability field is doubled at higher\npressures. While even longer chains show only insignificant improvements, we\ndiscuss various other options to stabilize H4-alkanes more. Our\nproof-of-principle results lay the groundwork to show that H4-alkanes can\nbecome viable hydrogen storage materials."
    },
    {
        "anchor": "Multiferroic van der Waals heterostructure FeCl$_2$/Sc$_2$CO$_2$:\n  Nonvolatile electrically switchable electronic and spintronic properties: Multiferroic van der Waals (vdW) heterostrucutres offers an exciting route\ntowards novel nanoelectronics and spintronics device technology. Here we\ninvestigate the electronic and transport properties of multiferroic vdW\nheterostructure composed of ferromagnetic FeCl$_2$ monolayer and ferroelectric\nSc$_2$CO$_2$ monolayer using first-principles density functional theory and\nquantum transport simulations. We show that FeCl$_2$/Sc$_2$CO$_2$\nheterostructure can be reversibly switched from semiconducting to half-metallic\nbehavior by electrically modulating the ferroelectric polarization states of\nSc$_2$CO$_2$. Intriguingly, the half-metallic phase exhibits a Type-III broken\ngap band alignment, which can be beneficial for tunnelling field-effect\ntransistor application. We perform a quantum transport simulation, based on a\n\\emph{proof-of-concept} two-terminal nanodevice, to demonstrate\nall-electric-controlled valving effects uniquely enabled by the nonvolatile\nferroelectric switching of the heterostructure. These findings unravels the\npotential of FeCl$_2$/Sc$_2$CO$_2$ vdW heterostructures as a building block for\ndesigning a next generation of ultimately compact information processing, data\nstorage and spintronics devices.",
        "positive": "Hybrid data-driven and physics-informed regularized learning of cyclic\n  plasticity with Neural Networks: An extendable, efficient and explainable Machine Learning approach is\nproposed to represent cyclic plasticity and replace conventional material\nmodels based on the Radial Return Mapping algorithm. High accuracy and\nstability by means of a limited amount of training data is achieved by\nimplementing physics-informed regularizations and the back stress information.\nThe off-loading of the Neural Network is applied to the maximal extent. The\nproposed model architecture is simpler and more efficient compared to existing\nsolutions from the literature, while representing a complete three-dimensional\nmaterial model. The validation of the approach is carried out by means of\nsurrogate data obtained with the Armstrong-Frederick kinematic hardening model.\nThe Mean Squared Error is assumed as the loss function which stipulates several\nrestrictions: deviatoric character of internal variables, compliance with the\nflow rule, the differentiation of elastic and plastic steps and the\nassociativity of the flow rule. The latter, however, has a minor impact on the\naccuracy, which implies the generalizability of the model for a broad spectrum\nof evolution laws for internal variables. Numerical tests simulating several\nload cases are shown in detail and validated for accuracy and stability."
    },
    {
        "anchor": "Quasi-van der Waals Epitaxial Growth of \u03b3'-GaSe Thin Films on\n  GaAs(111)B Substrates: GaSe is an important member of the post-transition metal chalcogenide family\nand is an emerging two-dimensional (2D) semiconductor material. Because it is a\nvan der Waals (vdW) material, it can be fabricated into atomic-scale ultrathin\nfilms, making it suitable for the preparation of compact, heterostructure\ndevices. In addition, GaSe possesses unusual optical and electronic properties,\nsuch as a shift from an indirect-bandgap single-layer film to a direct-bandgap\nbulk material, rare intrinsic p-type conduction, and nonlinear optical\nbehaviors. These properties make GaSe an appealing candidate for the\nfabrication of field-effect transistors, photodetectors, and photovoltaics.\nHowever, the wafer-scale production of pure GaSe single crystal thin films\nremains challenging. This study develops an approach for the direct growth of\nGaSe thin films on GaAs substrates using molecular beam epitaxy. It yields\nsmooth thin GaSe films with a {\\gamma}'-configuration, a recently-proposed\nnovel polymorph. We analyze the formation mechanism of {\\gamma}'-GaSe using\ndensity functional theory, finding that this polymorph is stabilized by Ga\nvacancies. Finally, we investigate the growth conditions of GaSe, providing\nvaluable insights for exploring 2D/3D quasi-vdW epitaxial growth.",
        "positive": "Control of Intermolecular Bonds by Deposition Rates at Room Temperature:\n  Hydrogen Bonds versus Metal Coordination in Trinitrile Monolayers: Self-assembled monolayers of 1,3,5-tris(4'-biphenyl-4\"-carbonitrile)benzene,\na large functional trinitrile molecule, on the (111) surfaces of copper and\nsilver under ultrahigh vacuum conditions were studied by scanning tunneling\nmicroscopy and low-energy electron diffraction. A densely packed\nhydrogen-bonded polymorph was equally observed on both surfaces. Additionally,\ndeposition onto Cu(111) yielded a well-ordered metal-coordinated porous\npolymorph that coexisted with the hydrogen-bonded structure. The required\ncoordination centers were supplied by the adatom gas of the Cu(111) surface. On\nAg(111), however, the well-ordered metal-coordinated network was not observed.\nDifferences between the adatom reactivities on copper and silver and the\nresulting bond strengths of the respective coordination bonds are held\nresponsible for this substrate dependence. By utilizing ultralow deposition\nrates, we demonstrate that on Cu(111) the adatom kinetics plays a decisive role\nin the expression of intermolecular bonds and hence structure selection."
    },
    {
        "anchor": "Statistical theory of thermodynamic and dynamic properties of the\n  RbHSO$_{4}$ ferroelectrics: Within the modified four-sublattice model of RbHSO$_{4}$ with taking into\naccount the piezoelectric coupling to the strains $\\varepsilon_i$,\n$\\varepsilon_4$, $\\varepsilon_5$, and $\\varepsilon_6$, the polarization\ncomponents, static and dynamic dielectric permittivity of clamped and free\ncrystal are calculated in the mean field approximation. At the proper choice of\nthe values of the theory parameters, a satisfactory quantitative description of\nthe available experimental data is obtained.",
        "positive": "Electrical conductivity of silver halide - cadmium halide systems: Very recent measurements of the electrical conductivity of solid systems AgX\n- CdX$_2$ (where X$\\equiv$Cl,Br) that form large areas of solid solutions, have\nshown that maximum conductivity occurs for a concentration around 20 mol\\% of\nthe cadmium halide. Here, we suggest a quantitative explanation of this\nphenomenon based on a model that was suggested (J. Appl. Phys. 103, 083552,\n(2008)) for estimating the compressibility of multiphased mixed crystals. In\naddition, explicit conditions are obtained which predict when such a\nconductivity maximum is expected to occur."
    },
    {
        "anchor": "Correlation of microdistortions with misfit volumes in High Entropy\n  Alloys: The yield strengths of High Entropy Alloys have recently been correlated with\nmeasured picometer-scale atomic distortions. Here, the root mean square\nmicrodistortion in a multicomponent alloy is shown to be nearly proportional to\nthe misfit-volume parameter that enters into a predictive model of solute\nstrengthening. Analysis of two model ternary alloy families, face-centered\ncubic Cr-Fe-Ni and body-centered cubic Nb-Mo-V, demonstrates the correlation\nover a wide composition space. The reported correlation of yield strength with\nmicrodistortion is thus a consequence of the correlation between\nmicrodistortion and misfit parameter and the derived dependence of yield\nstrength on the misfit parameter.",
        "positive": "Gateways towards quasicrystals: The experimental discovery of quasicrystals by D Shechtman, D Gratias, I\nBlech, and J W Cahn in 1984 provided the paradigm for a new type of long-range\norder of solid matter in nature. This discovery stimulated an explosion of new\nexperimental and theoretical research. In years prior to the discovery, there\nwas a very active development of various gateways to quasicrystals in\ntheoretical and mathematical physics. Without this conceptual basis, it would\nhave been impossible to grasp and explore efficiently the structure and\nphysical properties of quasicrystrals. The aim in what follows is to give a\nnon-technical and condensed account of the conceptual gateways to quasicrystals\nprior to their discovery."
    },
    {
        "anchor": "Multilayers of Zinc-Blende Half-Metals with Semiconductors: We report on first-principles calculations of multilayers of zinc-blende\nhalf-metallic ferromagnets CrAs and CrSb with III-V and II-VI semiconductors,\nin the [001] orientation. We examine the ideal and tetragonalised structures,\nas well as the case of an intermixed interface. We find that, as a rule,\nhalf-metallicity can be conserved throughout the heterostructures, provided\nthat the character of the local coordination and bonding is not disturbed. At\nthe interfaces with semiconductors, we describe a mechanism that can give also\na non-integer spin moment per interface transition atom, and derive a simple\nrule to evaluate it.",
        "positive": "Observation of an inter-sublattice exchange magnon in CoCr$_2$O$_4$ and\n  analysis of magnetic ordering: We report on an investigation of optical properties of multiferroic\nCoCr$_{2}$O$_{4}$ at terahertz frequencies in magnetic fields up to 30 T. Below\nthe ferrimagnetic transition (94 K), the terahertz response of\nCoCr$_{2}$O$_{4}$ is dominated by a magnon mode, which shows a steep\nmagnetic-field dependence. We ascribe this mode to an exchange resonance\nbetween two magnetic sublattices with different $g$-factors. In the framework\nof a simple two-sublattice model (the sublattices are formed by Co$^{2+}$ and\nCr$^{3+}$ ions), we find the inter-sublattice coupling constant, $\\lambda = -\n(18 \\pm 1)$ K, and trace the magnetization for each sublattice as a function of\nfield. We show that the Curie temperature of the Cr$^{3+}$ sublattice,\n$\\Theta_{2}$ = $(49 \\pm 2)$ K, coincides with the temperature range, where\nanomalies of the dielectric and magnetic properties of CoCr$_{2}$O$_{4}$ have\nbeen reported in literature."
    },
    {
        "anchor": "Co-occurrence of Superparamagnetism and Anomalous Hall Effect in Highly\n  Reduced Cobalt Doped Rutile TiO2 Films: We report a detailed magnetic and structural analysis of highly reduced Co\ndoped rutile TiO2 films displaying an anomalous Hall effect (AHE). The\ntemperature and field dependence of magnetization, and transmission electron\nmicroscopy clearly establish the presence of nano-sized superparamagnetic\ncobalt clusters of 8-10 nm size in the films at the interface. The\nco-occurrence of superparamagnetism and AHE raises questions regarding the use\nof the AHE as a test of the intrinsic nature of ferromagnetism in diluted\nmagnetic semiconductors.",
        "positive": "Vibrational Signatures in the THz Spectrum of 1,3-DNB: A\n  First-Principles and Experimental Study: Understanding the fundamental processes of light-matter interaction is\nimportant for detection of explosives and other energetic materials, which are\nactive in the infrared and terahertz (THz) region. We report a comprehensive\nstudy on electronic and vibrational lattice properties of structurally similar\n1,3-dinitrobenzene (1,3- DNB) crystals through first-principles electronic\nstructure calculations and THz spectroscopy measurements on polycrystalline\nsamples. Starting from reported x-ray crystal structures, we use\ndensity-functional theory (DFT) with periodic boundary conditions to optimize\nthe structures and perform linear response calculations of the vibrational\nproperties at zero phonon momentum. The theoretically identified normal modes\nagree qualitatively with those obtained experimentally in a frequency range up\nto 2.5 THz and quantitatively at much higher frequencies. The latter\nfrequencies are set by intra-molecular forces. Our results suggest that van der\nWaals dispersion forces need to be included to improve the agreement between\ntheory and experiment in the THz region, which is dominated by intermolecular\nmodes and sensitive to details in the DFT calculation. An improved comparison\nis needed to assess and distinguish between intra- and intermolecular\nvibrational modes characteristic of energetic materials."
    },
    {
        "anchor": "Structure-property relations characterizing the devitrification of Ni-Zr\n  glassy alloy thin films: The investigation of devitrification in thermally annealed nanodimensional\nglassy alloy thin films provides a comprehensive understanding of their thermal\nstability, which can be used to explore potential applications. The amorphous\nto crystalline polymorphous transformation of cosputtered NiZr alloy (Ni78Zr22\nat%) films, with a thickness lower than the reported critical limit of\ndevitrification, was studied through detailed structural characterization and\nmolecular dynamics (MD) simulations. Devitrification to a nanocrystalline state\n(Ni7Zr2 structure) was observed at 800 degC, with an increase in density\n(approx 3.6%) much higher than that achieved in bulk alloys. Variation in the\nmagnetic property of the films and the overall physical structure including\nmorphology and composition were examined before and after annealing. MD\nsimulations were employed to effectively elucidate not only the high\ndensification but also the increased magnetic moment after annealing, which was\ncorrelated with the simulated change in the coordination number around Ni\natoms. The structural relaxation process accompanying devitrification was\ndescribed as a disorder-to-order transformation while highlighting the crucial\nrole played by chemical short range order prevalent in glassy materials.",
        "positive": "Exploring electrical conductivity within mesoscopic phases of\n  semi-conducting PEDOT:PSS films by Broadband Dielectric Spectroscopy: Poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonic acid (PEDOT:PSS), an\noptically transparent organic semi-conductor, constitutes a suspension of\nconducting PEDOT:PSS grains, shelled by an insulating layer of PSS. While a\npercolation network enhances dc conductivity, structural and electrical\ninhomogenity hinters electric charge flow giving rise to capacitance effects.\nIn the present work, two distinct relaxation mechanisms are detected by\nBroadband Dielectric Spectroscopy (BDS). Double polarization mechamisms are\npredicted by bi-phase suspension dielectric theory. Within the frame of\ninterfacial polarization, we propose a methodology to have an insight into the\nlocal conductivity of the interior of mesoscopic conducting phase."
    },
    {
        "anchor": "Optical properties of ScN layers grown on Al$_{2}$O$_{3}$(0001) by\n  plasma-assisted molecular beam epitaxy: An accurate knowledge of the optical constants (refractive index $n$ and\nextinction coefficient $k$) of ScN is crucial for understanding the optical\nproperties of this binary nitride semiconductor as well as for its use in\noptoelectronic applications. Using spectroscopic ellipsometry in a spectral\nrange from far infrared to far ultraviolet (0.045-8.5 eV), we determine $n$ and\n$k$ of ScN layers grown on Al$_{2}$O$_{3}$(0001) substrates by plasma-assisted\nmolecular beam epitaxy. Fits of ellipsometry data return the energies of four\noscillators representing critical points in the band structure of ScN, namely,\n2.03, 3.89, 5.33, and 6.95 eV. As the infrared range is dominated by free\ncarriers, the vibrational properties of the layers are examined by Raman\nspectroscopy. Despite the rocksalt structure of ScN, several first-order phonon\nmodes are observed, suggesting a high density of point defects consistent with\nthe high electron density deduced from Hall measurements. Finally,\nphotoluminescence measurements reveal an emission band slightly above the\nlowest direct bandgap. We attribute the redshift of the peak emission energy\nfrom 2.3 to 2.2 eV with increasing layer thickness to a reduction of the O\nconcentration in the layers.",
        "positive": "Room-temperature antiferromagnetic memory resistor: The bistability of ordered spin states in ferromagnets (FMs) provides the\nmagnetic memory functionality. Traditionally, the macroscopic moment of ordered\nspins in FMs is utilized to write information on magnetic media by a weak\nexternal magnetic field, and the FM stray field is used for reading. However,\nthe latest generation of magnetic random access memories demonstrates a new\nefficient approach in which magnetic fields are replaced by electrical means\nfor reading and writing. This concept may eventually leave the sensitivity of\nFMs to magnetic fields as a mere weakness for retention and the FM stray fields\nas a mere obstacle for high-density memory integration. In this paper we report\na room-temperature bistable antiferromagnetic (AFM) memory which produces\nnegligible stray fields and is inert in strong magnetic fields. We use a\nresistor made of an FeRh AFM whose transition to a FM order 100 degrees above\nroom-temperature, allows us to magnetically set different collective directions\nof Fe moments. Upon cooling to room-temperature, the AFM order sets in with the\ndirection the AFM moments pre-determined by the field and moment direction in\nthe high temperature FM state. For electrical reading, we use an\nantiferromagnetic analogue of the anisotropic magnetoresistance (AMR). We\nreport microscopic theory modeling which confirms that this archetypical\nspintronic effect discovered more than 150 years ago in FMs, can be equally\npresent in AFMs. Our work demonstrates the feasibility to realize\nroom-temperature spintronic memories with AFMs which greatly expands the\nmagnetic materials base for these devices and offers properties which are\nunparalleled in FMs."
    },
    {
        "anchor": "Perspective: Towards the predictive discovery of ambipolarly dopable\n  ultra-wide-band-gap semiconductors: the case of rutile GeO$_2$: Ultrawide-band-gap (UWBG) semiconductors are promising for fast, compact, and\nenergy-efficient power-electronics devices. Their wider band gaps result in\nhigher breakdown electric fields that enable high-power switching with a lower\nenergy loss. Yet, the leading UWBG semiconductors suffer from intrinsic\nmaterials limitations with regards to their doping asymmetry that impedes their\nadoption in CMOS technology. Improvements in the ambipolar doping of UWBG\nmaterials will enable a wider range of applications in power electronics as\nwell as deep- UV optoelectronics. These advances can be accomplished through\ntheoretical insights on the limitations of current UWBG materials coupled with\nthe computational prediction and experimental demonstration of alternative UWBG\nsemiconductor materials with improved doping and transport properties. As an\nexample, we discuss the case of rutile GeO$_2$ (r-GeO$_2$), a water-insoluble\nGeO$_2$ polytype which is theoretically predicted to combine an ultra-wide gap\nwith ambipolar dopability, high carrier mobilities, and a higher thermal\nconductivity than \\b{eta}-Ga$_2$O$_3$. The subsequent realization of\nsingle-crystalline r-GeO$_2$ thin films by molecular beam epitaxy provides the\nopportunity to realize r-GeO$_2$ for electronic applications. Future efforts\ntowards the predictive discovery and design of new UWBG semiconductors include\nadvances in first-principles theory and high-performance computing software, as\nwell as the demonstration of controlled doping in high-quality thin films with\nlower dislocation densities and optimized film properties.",
        "positive": "Magneto-optical Kerr effect and magnetoelasticity in weak ferromagnetic\n  RuF$_4$ monolayer: Considerable research interest has been attracted to noncollinear magnetic\nstructures for their intriguing physics and promising applications. In this\nwork, based on relativistic density functional theory, we reveal the\ninteresting magnetic order and relevant properties in monolayer RuF$_4$, which\ncan be exfoliated from its bulk phase. Although the spins on Ru ions are almost\nantiferromagnetically aligned between nearest-neighbors, weak ferromagnetism is\ngenerated because of the antisymmetric Dzyaloshinskii-Moriya interaction as\nwell as the single-ion anisotropy. A prominent magneto-optical Kerr effect can\nbe observed for this antiferromagnet, similar to those of regular strong\nferromagnets. In addition, a uniaxial strain can induce a ferroelastic\nswitching together with the in-plane rotation of spin direction, giving rise to\na strong intrinsic magnetoelasticity. Our work not only suggests an alternative\ndirection for two-dimensional magnetic materials, but also provides hints to\nfuture devices based on antiferromagnetic magnetoelastic or magneto-optical\nmaterials."
    },
    {
        "anchor": "The nitrogen-vacancy colour centre in diamond: The nitrogen-vacancy (NV) colour centre in diamond is an important physical\nsystem for emergent quantum technologies, including quantum metrology,\ninformation processing and communications, as well as for various\nnanotechnologies, such as biological and sub-diffraction limit imaging, and for\ntests of entanglement in quantum mechanics. Given this array of existing and\npotential applications and the almost 50 years of NV research, one would expect\nthat the physics of the centre is well understood, however, the study of the NV\ncentre has proved challenging, with many early assertions now believed false\nand many remaining issues yet to be resolved. This review represents the first\ntime that the key empirical and ab initio results have been extracted from the\nextensive NV literature and assembled into one consistent picture of the\ncurrent understanding of the centre. As a result, the key unresolved issues\nconcerning the NV centre are identified and the possible avenues for their\nresolution are examined.",
        "positive": "Giant exchange bias and ferromagnetism in the CoO shell of Co/CoO-MgO\n  core-shell nanoparticles: Using magnetron sputtering, we produced a series of Co/CoO-MgO nanoparticles\non Si(100) substrates. High-resolution transmission electron microscopy (HRTEM)\nimage shows that small isolated Co-clusters (core) covered with CoO (shells)\nwith a size of a few nm embedded in a MgO matrix. Resistivity as a function of\nCo atomic ratio exhibits a distinct percolation threshold with a sharp decrease\naround 69% Co content. Across the threshold, the resistivity drops about 7\norders of magnitude. For a sample at this percolation critical threshold, we\nhave observed a giant exchange bias field HE=2460 Oe at T= 2K, and using soft\nx-ray magnetic circular dichroism at the Co-L2,3 edge, we have detected a\nferromagnetic (FM) signal originating from the antiferromagnetic CoO shell.\nMoreover, decreasing the Mg-impurities will reduce the FM signal from CoO shell\n(namely the uncompensated spin density) and the size of HE, thus directly\nsupport the uncompensated spin model."
    },
    {
        "anchor": "New Diluted Ferromagnetic Semiconductor isostructural to 122 type iron\n  pnictide superconductor with TC up to 180 K: Diluted magnetic semiconductors (DMS) have received much attention due to its\npotential applications to spintronics devices. A prototypical system (Ga,Mn)As\nhas been widely studied since 1990s. The simultaneous spin and charge doping\nvia hetero-valence (Ga3+,Mn2+) substitution, however, resulted in severely\nlimited solubility without availability of bulk specimens. Previously we\nsynthesized a new diluted ferromagnetic semiconductor of bulk Li(Zn,Mn)As with\nTc up to 50K, where isovalent (Zn,Mn) spin doping was separated from charge\ncontrol via Li concentrations. Here we report the synthesis of a new diluted\nferromagnetic semiconductor (Ba1-xKx)(Zn1-yMny)2As2, isostructural to iron 122\nsystem, where holes are doped via (Ba2+, K1+), while spins via (Zn2+,Mn2+)\nsubstitutions. Bulk samples with x=0.1-0.3 and y=0.05-0.15 exhibit\nferromagnetic order with TC up to 180K, comparable to that of record high Tc\nfor Ga(MnAs), significantly enhanced than Li(Zn,Mn)As. Moreover the\n(Ba,K)(Zn,Mn)2As2 shares the same 122 crystal structure with semiconducting\nBaZn2As2, antiferromagnetic BaMn2As2, and superconducting (Ba,K)Fe2As2, which\nmakes them promising to the development of multilayer functional devices.",
        "positive": "Elastic anisotropy and thermal properties of extended linear chain\n  compounds MV$_2$Ga$_4$ (M = Sc, Zr, Hf) from ab-initio calculations: MV$_2$Ga$_4$ (M = Sc, Zr, Hf) compounds belong to an emerging class of\nmaterials showing a unique combination of unusual superconducting behavior with\nextended linear chains in the crystal structure. In order to gain insights\n{into} its mechanical and thermal properties, we have performed\nfirst-principles electronic-structure calculations in the framework of the\nDensity Functional Theory (DFT). From the calculated second-order elastic\nconstants, we have systematically shown that the extended linear vanadium chain\nsubstructures indeed give rise to an anisotropic regime in the elastic and\nmechanical moduli. The high density of valence and conduction electrons along\nthe linear vanadium chains leads to a directional dependence of the reciprocal\nlinear compressibility, Young's modulus and shear modulus. Poisson's ratio for\nseveral elongation directions is also drastically affected by the presence of\nextended V chains. If the elongation is along the V chains, all compounds\nexhibit {practically} the same Poisson ratio in directions perpendicular to it,\nfurther highlighting the importance of the V chains to the mechanical\nproperties. Moreover, based on our results, we have discussed the possible\nconsequences of the elastic anisotropy on the superconducting properties of the\ncompounds. Finally, using the Debye-Gr\\\"uneisen approximation, our calculations\nof thermal properties show {a good agreement with the available experimental\nlow temperature heat capacity data above the superconducting critical\ntemperature."
    },
    {
        "anchor": "The dynamic evolution of swelling in nickel concentrated solid solution\n  alloys through in situ property monitoring: Defects and microstructural features spanning the atomic level to the\nmicroscale play deterministic roles in the expressed properties of materials.\nYet studies of material evolution in response to environmental stimuli most\noften correlate resulting performance with one dominant microstructural feature\nonly. Here, the dynamic evolution of swelling in a series of Ni-based\nconcentrated solid solution alloys under high-temperature irradiation exposure\nis observed using continuous, in situ measurements of thermoelastic properties\nin bulk specimens. Unlike traditional evaluation techniques which account only\nfor volumetric porosity identified using electron microscopy, direct property\nevaluation provides an integrated response across all defect length scales. In\nparticular, the evolution in elastic properties during swelling is found to\ndepend significantly on the entire size spectrum of defects, from the nano- to\nmeso-scales, some of which are not resolvable in imaging. Observed changes in\nthermal transport properties depend sensitively on the partitioning of\nelectronic and lattice thermal conductivity. This emerging class of in situ\nexperiments, which directly measure integrated performance in relevant\nconditions, provides unique insight into material dynamics otherwise\nunavailable using traditional methods.",
        "positive": "Who pumps spin current into nonmagnetic-metal (NM) layer in YIG/NM\n  multilayers at ferromagnetic resonance?: Spin pumping in Yttrium-iron-garnet (YIG)/nonmagnetic-metal (NM) layer\nsystems under ferromagnetic resonance (FMR) conditions is a popular method of\ngenerating spin current in the NM layer. A good understanding of the spin\ncurrent source is essential in extracting spin Hall angle of the NM and in\npotential spintronics applications. It is widely believed that spin current is\npumped from precessing YIG magnetization into NM layer. Here, by combining\nmicrowave absorption and DC-voltage measurements on YIG/Pt and YIG/NM1/NM2\n(NM1=Cu or Al, NM2=Pt or Ta), we unambiguously showed that spin current in NM\ncame from the magnetized NM surface (in contact with YIG) due to the magnetic\nproximity effect (MPE), rather than the precessing YIG magnetization. This\nconclusion is reached through our unique detecting method where the FMR\nmicrowave absorption of the magnetized NM surface, hardly observed in the\nconventional FMR experiments, was greatly amplified when the electrical\ndetection circuit was switched on."
    },
    {
        "anchor": "The role of disorder in the synthesis of metastable zinc zirconium\n  nitrides: In materials science, it is often assumed that ground state crystal\nstructures predicted by density functional theory are the easiest polymorphs to\nsynthesize. Ternary nitride materials, with many possible metastable\npolymorphs, provide a rich materials space to study what influences\nthermodynamic stability and polymorph synthesizability. For example, ZnZrN2 is\ntheoretically predicted at zero Kelvin to have an unusual layered \"wurtsalt\"\nground state crystal structure with compelling optoelectronic properties, but\nit is unknown whether this structure can be realized experimentally under\npractical synthesis conditions. Here, we use combinatorial sputtering to\nsynthesize hundreds of ZnxZr1-xNy thin film samples, and find metastable\nrocksalt-derived or boron-nitride-derived structures rather than the predicted\nwurtsalt structure. Using a statistical polymorph sampler approach, it is\ndemonstrated that although rocksalt is the least stable polymorph at zero\nKelvin, it becomes the most stable polymorph at high effective temperatures\nsimilar to those achieved using this sputter deposition method, and thus\ncorroborates experimental results. Additional calculations show that this\ndestabilization of the wurtsalt polymorph is due to configurational entropic\nand enthalpic effects, and that vibrational contributions are negligible.\nSpecifically, rocksalt- and boron-nitride-derived structures become the most\nstable polymorphs in the presence of disorder because of higher tolerances to\ncation cross-substitution and off-stoichiometry than the wurtsalt structure.\nThis understanding of the role of disorder tolerance in the synthesis of\ncompeting polymorphs can enable more accurate predictions of synthesizable\ncrystal structures and their achievable material properties.",
        "positive": "Variational finite-difference representation of the kinetic energy\n  operator: A potential disadvantage of real-space-grid electronic structure methods is\nthe lack of a variational principle and the concomitant increase of total\nenergy with grid refinement. We show that the origin of this feature is the\nsystematic underestimation of the kinetic energy by the finite difference\nrepresentation of the Laplacian operator. We present an alternative\nrepresentation that provides a rigorous upper bound estimate of the true\nkinetic energy and we illustrate its properties with a harmonic oscillator\npotential. For a more realistic application, we study the convergence of the\ntotal energy of bulk silicon using a real-space-grid density-functional code\nand employing both the conventional and the alternative representations of the\nkinetic energy operator."
    },
    {
        "anchor": "The structural, elastic and optical properties of ScM (M = Rh, Cu, Ag,\n  Hg) intermetallic compounds under pressure by ab initio simulations: The influence of pressure on the structural and elastic properties of ScM (M\n= Rh, Cu, Ag, Hg) compounds has been performed by using ab initio approach\npseudopotential plane- wave method based on the density functional theory\nwithin the generalized gradient approximation (GGA). The optical properties\nhave been investigated under zero pressure. It is found that the optimized\nlattice parameters for all metals are in good agreement with the experimental\ndata and other available theoretical values.",
        "positive": "Fermi surface effects in solid-solid phase transitions in simple metals\n  under pressure: I discuss the behaviour of Group 1 and 2 elements under pressure, describing\ncrystallography based on diamond anvil pressure cell experiments and electronic\nstructure calculations. In addition to these precise methods, we discuss more\nintuitive pictures of both the electronic driving force for the transitions,\nand the structural motifs which optimise the electronic energy by opening\npseudogaps at the Fermi energy."
    },
    {
        "anchor": "Strong ultrafast demagnetization due to the intraband transitions: Demagnetization in ferromagnetic transition metals driven by a femtosecond\nlaser pulse is a fundamental problem in solid state physics, and its\nunderstanding is essential to the development of spintronics devices. Ab initio\ncalculation of time-dependent magnetic moment in the velocity gauge so far has\nnot been successful in reproducing the large amount of demagnetization observed\nin experiments. In this work, we propose a method to incorporate intraband\ntransitions within the velocity gauge through a convective derivative in the\ncrystal momentum space. Our results for transition-element bulk crystals (bcc\nFe, hcp Co and fcc Ni) based on the time-dependent quantum Liouville equation\nshow a dramatic enhancement in the amount of demagnetization after the\ninclusion of an intraband term, in agreement with experiments. We also find\nthat the effect of intraband transitions to each ferromagnetic material is\ndistinctly different because of their band structure and spin property\ndifferences. Our finding has a far-reaching impact on understanding of\nultrafast demagnetization.",
        "positive": "Optical manipulation of the topological phase in ZrTe5 revealed by time-\n  and angle-resolved photoemission: High-resolution time- and angle-resolved photoemission measurements were\nconducted on the topological insulator ZrTe5. With strong femtosecond\nphotoexcitation, a possible ultrafast phase transition from a weak to a strong\ntopological insulating phase was experimentally realized by recovering the\nenergy gap inversion in a time scale that was shorter than 0.15 ps. This\nphotoinduced transient strong topological phase can last longer than 2 ps at\nthe highest excitation fluence studied, and it cannot be attributed to the\nphotoinduced heating of electrons or modification of the conduction band\nfilling. Additionally, the measured unoccupied electronic states are consistent\nwith the first-principles calculation based on experimental crystal lattice\nconstants, which favor a strong topological insulating phase. These findings\nprovide new insights into the longstanding controversy about the strong and\nweak topological properties in ZrTe5, and they suggest that many-body effects\nincluding electron-electron interactions must be taken into account to\nunderstand the equilibrium weak topological insulating phase in ZrTe5."
    },
    {
        "anchor": "Temperature dependence of the bandgap of Eu doped {ZnCdO/ZnO}30\n  multilayer structures: In situ Eu-doped {ZnCdO/ZnO}30 multilayer systems were grown on p-type\nSi-substrates and on quartz substrates by plasma-assisted molecular beam\nepitaxy. Various Eu concentrations in the samples were achieved by controlling\ntemperature of the europium effusion cell. The properties of as-grown and\nannealed {ZnCdO/ZnO}30:Eu multilayers were investigated using secondary ion\nmass spectrometry (SIMS) and X-ray diffraction methods. SIMS measurements\nshowed that annealing at 700{\\deg}C and 900{\\deg}C practically did not change\nthe Eu concentration and the rare earth depth profiles are uniform. It was\nfound that the band gap depends on the concentration of Eu and it was changed\nby rapid thermal annealing. Varshni and Bose-Einstein equations were used to\ndescribe the temperature dependence of the band gap of {ZnCdO/ZnO}30:Eu\nmultilayer structures and Debye and Einstein temperatures were obtained.",
        "positive": "Nanotube caps on Ni, Fe, and NiFe nano particles: A path to chirality\n  selective growth: Carbon nanotubes have properties depending on the arrangement of carbon atoms\non the tube walls, called chirality. Also it has been tried to grow nanotubes\nof only one chirality for more than a decade it is still not possible today. A\nnarrowing of the distribution of chiralities, however, which is a first step\ntowards chirality control, has been observed for the growth of nanotubes on\ncatalysts composed of nickel and iron. In this paper, we have calculated\ncarbon-metal bond energies, adhesion energies and charge distributions of\ncarbon nanotube caps on Ni, Fe and NiFe alloy clusters using density functional\ntheory. A growth model using the calculated energies was able to reproduce the\nexperimental data of the nanotube growth on the alloy catalysts. The electronic\ncharge was found to be redistributed from the catalyst particles to the edges\nof the nanotube caps in dependence of the chiral angles of the caps increasing\nthe reactivity of the edge atoms. Our study develops an explanation for the\nchirality enrichment in the carbon nanotube growth on alloy catalyst particles."
    },
    {
        "anchor": "Micromagnetics of single and double point contact spin torque\n  oscillators: In this paper we numerically conduct micromagnetic modelling to optimize\ncomputational boundaries of magnetic thin-film elements applicable to single\nand double point contact spin torque nano-oscillators. Different boundary\nconditions have been introduced to compensate spin waves reflections at\nboundaries that are based on extended layers, absorbing boundaries, and focal\npoint methods and are compared with a technique based on scattering theory. A\nsurface roughness boundary model is presented which is modelled according to\nthe Rayleigh criterion to minimize specular reflections at computational\nboundaries. It is shown that the surface roughness model disperses the\nreflected spin waves and improves the signal to background noise ratio. The\nmodel is tested in comparison to conventional approaches such as extended layer\nsystems, variable damping constant and focal point methods for double point\ncontacts. The surface roughness model gives solutions that are stable in time,\nin qualitative agreement with experiments and capable to reproduce phenomena\nsuch as phase locking in double point contacts.",
        "positive": "Response to \"Comment on Ferroelectrically induced weak ferromagnetism by\n  design,\" by R. de Sousa and J. E. Moore, arXiv:0806.2142: A recent Comment [arXiv:0806.2142] has argued that \"there is a simple duality\nbetween A-site and B-site\" R3c ABO$_3$ materials and that our Letter [PRL 100,\n167203 (2208)] \"breaks this duality by ignoring a non-polar distortion that is\ndirectly measured in crystallography.\" Here we point out that this is not\ncorrect. The Comment contains three elementary crystallographic errors. In this\nresponse we address each error in some detail."
    },
    {
        "anchor": "Origin of high piezoelectricity at the morphotropic phase boundary (MPB)\n  in (Pb0.94Sr0.06)(ZrxTi1-x)O3: In this work, we address the issue of peaking of piezoelectric response at a\nparticular composition in the morphotropic phase boundary (MPB) region of\n(Pb0.940Sr0.06)(ZrxTi1-x)O3 (PSZT) piezoelectric ceramics. We present results\nof synchrotron x-ray powder diffraction, dielectric, piezoelectric and sound\nvelocity studies to critically examine the applicability of various models for\nthe peaking of physical properties. It is shown that the models based on the\nconcepts of phase coexistence, polarization rotation due to monoclinic\nstructure, tricritical point and temperature dependent softening of elastic\nmodulus may enhance the piezoelectric response in the MPB region in general but\ncannot explain its peaking at a specific composition. Our results reveal that\nthe high value of piezoelectric response for the MPB compositions in PSZT at\nx=0.530 is due to the softening of the elastic modulus as a function of\ncomposition. The softening of elastic modulus facilitates the generation of\nlarge piezoelectric strain and polarization on approaching the MPB composition\nof x=0.530. This new finding based on the softening of elastic modulus may pave\nthe way forward for discovering/designing new lead-free environmentally\nfriendly piezoelectric materials and revolutionize the field of piezoelectric\nceramics.",
        "positive": "Strong magneto-optical and anomalous transport manifestations in\n  two-dimensional van der Waals magnets Fe$_n$GeTe$_2$ ($n$ = 3, 4, 5): Utilizing the first-principles calculations together with the group theory\nanalysis, we systematically investigate the magnetocrystalline anisotropy\nenergy, magneto-optical effect, and anomalous transport properties (including\nanomalous Hall, Nernst, and thermal Hall effects) of monolayer and bilayer\nFe$_n$GeTe$_2$ ($n$ = 3, 4, 5). The monolayer Fe$_n$GeTe$_2$ ($n$ = 3, 4, 5)\nexhibits the out-of-plane, in-plane, and in-plane ferromagnetic orders with\nconsiderable magnetocrystalline anisotropy energies of -3.17, 4.42, and 0.58\nmeV/f.u., respectively. Ferromagnetic order is predicted in bilayer\nFe$_4$GeTe$_2$ while antiferromagnetic order prefers in bilayer Fe$_3$GeTe$_2$\nand Fe$_5$GeTe$_2$. The group theory analysis reveals that in addition to\nmonolayer ferromagnetic Fe$_n$GeTe$_2$ ($n$ = 3, 4, 5), the magneto-optical and\nanomalous transport phenomena surprisingly exist in bilayer antiferromagnetic\nFe$_5$GeTe$_2$, which is much rare in realistic collinear antiferromagnets. If\nspin magnetic moments of monolayer and bilayer Fe$_n$GeTe$_2$ are reoriented\nfrom the in-plane to out-of-plane direction, the magneto-optical and anomalous\ntransport properties enhance significantly, presenting strong magnetic\nanisotropy. We also demonstrate that the anomalous Hall effect decreases with\nthe temperature increases. The gigantic anomalous Nernst and thermal Hall\neffects are found in monolayer and bilayer ferromagnetic Fe$_n$GeTe$_2$, and\nthe largest anomalous Nernst and thermal Hall conductivities, respectively, of\n-3.31 A/Km and 0.22 W/Km at 130 K are observed in bilayer ferromagnetic\nFe$_4$GeTe$_2$. Especially, bilayer antiferromagnetic Fe$_5$GeTe$_2$ exhibits\nlarge zero-temperature anomalous Hall conductivity of 2.63 e$^2$/h as well as\nanomalous Nernst and thermal Hall conductivities of 2.76 A/Km and 0.10 W/Km at\n130 K, respectively."
    },
    {
        "anchor": "Wavelength-dependent reflectivity changes on gold at elevated electronic\n  temperatures: Upon the excitation by an ultrashort laser pulse the conditions in a material\ncan drastically change, altering its optical properties and therefore the\nrelative amount of absorbed energy, a quan- tity relevant for determining the\ndamage threshold and for developing a detailed simulation of a structuring\nprocess. The subject of interest in this work is the d-band metal gold which\nhas an absorption edge marking the transition of free valence electrons and an\nabsorbing deep d-band with bound electrons. Reflectivity changes are observed\nin experiment over a broad spectral range at ablation conditions. To understand\nthe involved processes the laser excitation is modeled by a com- bination of\nfirst principle calculations with a two-temperature model. The description is\nkept most general and applied to realistically simulate the transfer of the\nabsorbed energy of a Gaussian laser pulse into the electronic system at every\npoint in space at every instance of time. An electronic temperature-dependent\nreflectivity map is calculated, describing the out of equilibrium reflectivity\nduring laser excitation for photon energies from 0.9 - 6.4 eV, including inter-\nand intra-band transi- tions and a temperature-dependent damping factor. The\nmain mechanisms are identified explaining the electronic temperature-dependent\nchange in reflectivity: broadening of the edge of the occu- pied/unoccupied\nstates around the chemical potential $\\mu$, also leading to a shift of the\n$\\mu$ and an increase of the collision rate of free s/p-band electrons with\nbound d-band holes.",
        "positive": "Order out of a Coulomb phase and Higgs transtion: frustrated transverse\n  interactions of Nd2Zr2O7: The pyrochlore material Nd$_2$Zr$_2$O$_7$ with an \"all-in-all-out\" (AIAO)\nmagnetic order shows novel quantum moment fragmentation with gapped flat\ndynamical spin ice modes. The parameterized spin Hamiltonian with a dominant\nfrustrated ferromagnetic transverse term reveals a proximity to a U(1) spin\nliquid. Here we study magnetic excitations of Nd$_2$Zr$_2$O$_7$ above the\nordering temperature ($T_\\text{N}$) using high-energy-resolution inelastic\nneutron scattering. We find strong spin ice correlations at zero energy with\nthe disappearance of gapped magnon excitations of the AIAO order. It seems that\nthe gap to the dynamical spin ice closes above $T_\\text{N}$ and the system\nenters a quantum spin ice state competing with and suppressing the AIAO order.\nClassical Monte Carlo, molecular dynamics and quantum boson calculations\nsupport the existence of a Coulombic phase above $T_\\text{N}$. Our findings\nrelate the magnetic ordering of Nd$_2$Zr$_2$O$_7$ with the Higgs mechanism and\nprovide explanations for several previously reported experimental features."
    },
    {
        "anchor": "Simultaneously Magnetic- and Electric-dipole Active Spin Excitations\n  Govern the Static Magnetoelectric Effect in Multiferroic Materials: We derive a sum rule to demonstrate that the static magnetoelectric (ME)\neffect is governed by optical transitions that are simultaneously excited via\nthe electric and magnetic components of light. By a systematic analysis of\nmagnetic point groups, we show that the ME sum rule is applicable to a broad\nvariety of non-centrosymmetric magnets including ME multiferroic compounds. Due\nto the dynamical ME effect, the optical excitations in these materials can\nexhibit directional dichroism, i.e. the absorption coefficient can be different\nfor counter-propagating light beams. According to the ME sum rule, the\nmagnitude of the linear ME effect of a material is mainly determined by the\ndirectional dichroism of its low-energy optical excitations. Application of the\nsum rule to the multiferroic Ba$_2$CoGe$_2$O$_7$, Sr$_2$CoSi$_2$O$_7$ and\nCa$_2$CoSi$_2$O$_7$ shows that in these compounds the static ME effect is\nmostly governed by the directional dichroism of the spin-wave excitations in\nthe GHz-THz spectral range. On this basis, we argue that the studies of\ndirectional dichroism and the application of ME sum rule can promote the\nsynthesis of new materials with large static ME effect.",
        "positive": "On energetics of allotrope transformations in transition-metal diborides\n  via plane-by-plane shearing: Transition metal diborides crystallise in the $\\alpha$, $\\gamma$, or $\\omega$\ntype structure, in which pure transition metal layers alternate with pure boron\nlayers stacked along the hexagonal [0001] axis. Here we view the prototypes as\ndifferent stackings of the transition metal planes and suppose they can\ntransform from one into another by a displacive transformation. Employing\nfirst-principles calculations, we simulate sliding of individual planes in the\ngroup IV-VII transition metal diborides along a transformation pathway\nconnecting the $\\alpha$, $\\gamma$, and $\\omega$ structure. Chemistry-related\ntrends are predicted in terms of energetic and structural changes along a\ntransformation pathway, together with the mechanical and dynamical stability of\nthe different stackings. Our results suggest that MnB$_2$ and MoB$_2$ possess\nthe overall lowest sliding barriers among the investigated TMB$_2$s.\nFurthermore, we discuss trends in strength and ductility indicators, including\nYoung's modulus or Cauchy pressure, derived from elastic constants."
    },
    {
        "anchor": "Pawpyseed: Perturbation-extrapolation band shifting corrections for\n  point defect calculations: Significant progress has been made recently in the automation and\nstandardization of ab initio point defect calculations. However, the task of\ndeveloping, implementing, and benchmarking charge corrections for density\nfunctional theory (DFT) point defect calculations is still an open challenge.\nHere we present a high-performance Python package called pawpyseed, which can\nread PAW DFT wave functions and calculate the overlap between wavefunctions\nfrom different structures. Using pawpyseed, we implement a new band shifting\ncorrection derived from first order perturbation theory. We benchmark this\nmethod by calculating the transition levels of several point defects in silicon\nand comparing to experimental and hybrid functional results. The new band\nshifting method can shift single-particle energies to improve transition level\npredictions and can be automated and parallelized using pawpyseed, suggesting\nit could be a useful method for high-throughput point defect calculations.",
        "positive": "Coherent and Incoherent Thermal Transport in Nanomeshes: Coherent thermal transport in nanopatterned structures is a topic of\nconsiderable interest, but whether it occurs in certain structures remains\nunclear due to poor understanding of which phonons conduct heat. Here, we\nperform the first fully three-dimensional, frequency-dependent simulations of\nthermal transport in nanomeshes by solving the Boltzmann transport equation\nwith a novel, efficient Monte Carlo method. From the spectral information in\nour simulations, we show that thermal transport in nanostructures that can be\ncreated with available lithographic techniques is dominated by incoherent\nboundary scattering at room temperature. Our result provides important insights\ninto the conditions required for coherent thermal transport to occur in\nartificial structures."
    },
    {
        "anchor": "van der Waals density functionals built upon the electron-gas tradition:\n  Facing the challenge of competing interactions: The theoretical description of sparse matter attracts much interest, in\nparticular for those ground-state properties that can be described by density\nfunctional theory (DFT). One proposed approach, the van der Waals density\nfunctional (vdW-DF) method, rests on strong physical foundations and offers\nsimple yet accurate and robust functionals. A very recent functional within\nthis method called vdW-DF-cx [K. Berland and P. Hyldgaard, Phys. Rev. B 89,\n035412] stands out in its attempt to use an exchange energy derived from the\nsame plasmon-based theory from which the nonlocal correlation energy was\nderived. Encouraged by its good performance for solids, layered materials, and\naromatic molecules, we apply it to several systems that are characterized by\ncompeting interactions. These include the ferroelectric response in PbTiO$_3$,\nthe adsorption of small molecules within metal-organic frameworks (MOFs), the\ngraphite/diamond phase transition, and the adsorption of an aromatic-molecule\non the Ag(111) surface. Our results indicate that vdW-DF-cx is overall well\nsuited to tackle these challenging systems. In addition to being a competitive\ndensity functional for sparse matter, the vdW-DF-cx construction presents a\nmore robust general purpose functional that could be applied to a range of\nmaterials problems with a variety of competing interactions.",
        "positive": "Oxygen vacancies at the origin of pinned moments in oxide interfaces:\n  the example of tetragonal CuO/SrTiO$_3$: Obtaining an accurate theoretical description of the emergent phenomena in\noxide heterostructures is a major challenge. Recently, intriguing paramagnetic\nspin and pinned orbital moments have been discovered by x-ray magnetic circular\ndichro\\\"ism measurements at the Cu $L_{2,3}$-edge of a tetragonal CuO/SrTiO$_3$\nheterostructure. Using first principles calculations, we propose a scenario\nthat explains both types of moments, based on the formation of oxygen vacancies\nin the TiO$_2$ interface layer. We show the emergence of a paramagnetic 2D\nelectron gas hosted in the interface CuO layer. It is invisible at the Ti\n$L_{2,3}$-edge since the valence of the Ti atoms remains unchanged. Strong\nstructural distortions breaking both the local and global fourfold rotation\n$C_4$ symmetries at the interface lead to the in-plane pinning of the Cu\norbital moment close to the vacancy. Our results, and in particular the pinning\nof the orbital moment, may have implications for other systems, especially\nmonoxide/dioxide interfaces with similar metal-oxygen bond length and weak\nspin-orbit coupling."
    },
    {
        "anchor": "Rectangular carbon nitrides C4N monolayers with a zigzag buckled\n  structure: Quasi-one-dimensional Dirac nodal lines and topological flat edge\n  states: Due to the flexibility of C and N atoms in forming different types of bonds,\nthe prediction of new two-dimensional (2D) carbon nitrides is a hot topic in\nthe field of carbon-based materials. Using first-principles calculations, we\npropose two C4N monolayers with a zigzag buckled (ZB) structure. The ZB C4N\nmonolayers contain raised-C (raised-N) atoms with sp3 hybridization, different\nfrom the traditional 2D graphene-like carbon nitride materials with sp2\nhybridization. Interestingly, the band structures of the ZB C4N monolayers\nexhibit quasi-one-dimensional (quasi-1D) Dirac nodal line that results from the\ncorresponding quasi-1D structure of the zigzag carbon chains, which is\nessentially different from the more common ring-shaped nodal line. The quasi-1D\nDirac nodal line exhibits the following features: (i) gapless Dirac points,\n(ii) varying Fermi velocity, and (iii) slightly curved band along the\nhigh-symmetry path. All these features are successfully explained by our\nproposed tight-binding model that includes interactions up to the third\nnearest-neighbor. The Fermi velocity of the 2D system can reach 105 m/s, which\nis promising for applications in high-speed electronic devices. The topological\nflat band structure determined by the Zak phase and band inversion of the\ncorresponding 1D system is edge-dependent, which is corresponding to the\nSu-Schrieffer-Heeger model, providing to rich physical phenomena.",
        "positive": "Band structure and energy level alignment of chiral graphene nanoribbons\n  on silver surfaces: Chiral graphene nanoribbons are extremely interesting structures due to their\nlow bandgaps and potential development of spin-polarized edge states. Here, we\nstudy their band structure on low work function silver surfaces and assess the\neffect of charge transfer on their properties."
    },
    {
        "anchor": "Autonomous atomic Hamiltonian construction and active sampling of x-ray\n  absorption spectroscopy by adversarial Bayesian optimization: X-ray absorption spectroscopy (XAS) is a well-established method for in-depth\ncharacterization of the electronic structure due to its sensitivity to the\nlocal coordination and electronic states of the active ions. In practice\nhundreds of energy points should be sampled during the XAS measurement, most of\nwhich are redundant and do not contain important information. In addition, it\nis also a tedious procedure to estimate reasonable parameters in the atomic\nHamiltonian for mechanistic understanding. We implemented an Adversarial\nBayesian optimization (ABO) algorithm comprising two coupled BOs to\nautomatically fit the multiplet model Hamiltonian and meanwhile to sample\neffectively based on active learning. Taking NiO as an example, for simulated\nspectra which can be well fitted by the atomic model, we found that less than\n30 sampling points are enough to obtain the complete XAS with the corresponding\ncrystal field or charge transfer model, which can be selected based on\nintuitive hypothesis learning. Further application on the experimental spectra,\nit revealed that less than 80 sampling points can already give reasonable XAS\nand reliable atomic model parameters. Our ABO algorithm has a great potential\nfor future application in automated physics-driven XAS analysis and active\nlearning sampling.",
        "positive": "Nanoscale piezoelectric response across a single antiparallel\n  ferroelectric domain wall: Surprising asymmetry in the local electromechanical response across a single\nantiparallel ferroelectric domain wall is reported. Piezoelectric force\nmicroscopy is used to investigate both the in-plane and out-of- plane\nelectromechanical signals around domain walls in congruent and\nnear-stoichiometric lithium niobate. The observed asymmetry is shown to have a\nstrong correlation to crystal stoichiometry, suggesting defect-domain wall\ninteractions. A defect-dipole model is proposed. Finite element method is used\nto simulate the electromechanical processes at the wall and reconstruct the\nimages. For the near-stoichiometric composition, good agreement is found in\nboth form and magnitude. Some discrepancy remains between the experimental and\nmodeling widths of the imaged effects across a wall. This is analyzed from the\nperspective of possible electrostatic contributions to the imaging process, as\nwell as local changes in the material properties in the vicinity of the wall."
    },
    {
        "anchor": "Role of the dispersion force in modeling the interfacial properties of\n  molecule-metal interfaces: adsorption of thiophene on copper surfaces: We present density functional theory calculations of the geometry, adsorption\nenergy and electronic structure of thiophene adsorbed on Cu(111), Cu(110) and\nCu(100) surfaces. Our calculations employ dispersion corrections and\nself-consistent van der Waals density functionals (vdW-DFs). In terms of speed\nand accuracy, we find that the dispersion-energy-corrected Revised\nPerdue-Burke-Enzerhof (RPBE) functional is the \"best balanced\" method for\npredicting structural and energetic properties, while vdW-DF is also highly\naccurate if a proper exchange functional is used. Discrepancies between theory\nand experiment in molecular geometry can be solved by considering x-ray\ngenerated core-holes. However, the discrepancy concerning the adsorption site\nfor thiophene/Cu(100) remains unresolved and requires both further experiments\nand deeper theoretical analysis. For all the interfaces, the PBE functional\nreveals a covalent bonding picture which the inclusion of dispersive\ncontributions does not change to a vdW one. Our results provide a comprehensive\nunderstanding of the role of dispersive forces in modelling molecule-metal\ninterfaces.",
        "positive": "Plasma excitations of dressed Dirac electrons in graphene layers: The dispersion relation for the collective plasma excitations of optically\ndressed Dirac electrons in single and double graphene layers is calculated in\nthe random-phase approximation. The presence of circularly polarized light\ngives rise to an energy gap $E_g$ between the conduction and valence energy\nbands. The value of $E_g$ may be adjusted by varying the frequency and\nintensity of the light and could be much larger compared to that which is\ngenerated by spin-orbit coupling, and may reach values of the gap reported for\nepitaxially grown graphene. We report plasmon dispersion relations for various\nenergy gaps and separation between graphene layers. For a single graphene\nsheet, we find that plasmon modes may be excited for larger wave vector and\nfrequency when subjected to light. For double layers, we obtained an optical\nand phonon-like mode and found that the optical mode is not as sensitive as the\nphonon-like mode in the long wavelength limit when the layer separation is\nvaried, for a chosen $E_g$. Contrary to the notion that the effective mass\nacquired by Dirac electrons provides a crossover to two-dimensional electron\ngas (2DEG) behavior, we found that the response of dressed Dirac electrons to\nan external perturbation is governed by the Dirac cone $\\omega = v_F q$, where\n$_F$ is the Fermi velocity and $q$ is the wave vector. Consequently, the\ndressed electron plasma although massive still has Dirac origin giving rise to\ndifferences in the properties of the plasmon modes compared with those for the\n2DEG."
    },
    {
        "anchor": "Structure and dynamics of the negative thermal expansion material\n  Cd(CN)$_2$ under pressure: We use a combination of variable-temperature / variable-pressure neutron\npowder diffraction, variable-pressure inelastic neutron scattering, and quantum\nchemical calculations to interrogate the behaviour of the negative thermal\nexpansion (NTE) material $^{114}$Cd(CN)$_2$ under hydrostatic pressure. We\ndetermine the equation of state of the ambient-pressure phase, and discover the\nso-called `warm hardening' effect whereby the material becomes elastically\nstiffer as it is heated. We also identify a number of high-pressure phases, and\nmap out the phase behaviour of Cd(CN)$_2$ over the range $0\\leq p\\leq0.5$\\,GPa,\n$100\\leq T\\leq300$\\,K. As expected for an NTE material, the low-energy phonon\nfrequencies are found to soften under pressure, and we determine an effective\nGr{\\\"u}neisen parameter for these modes. Finally, we show that the elastic\nbehaviour of Cd(CN)$_2$ is sensitive to the local Cd coordination environment,\nwhich suggests an interplay between short- (phononic) and long-timescale\n(cyanide flips) fluctuations in Cd(CN)$_2$.",
        "positive": "Charge-density depinning at metal contacts of graphene field-effect\n  transistors: An anomalous distortion is often observed in the transfer characteristics of\ngraphene field-effect transistors. We fabricate graphene transistors with\nferromagnetic metal electrodes, which reproducibly display distorted transfer\ncharacteristics, and show that the distortion is caused by metal-graphene\ncontacts with no charge-density pinning effect. The pinning effect, where the\ngate voltage cannot tune the charge density of graphene at the metal\nelectrodes, has been experimentally observed; however, a pinning-free interface\nis achieved with easily-oxidizable metals. The distortion should be a serious\nproblem for flexible electronic devices with graphene."
    },
    {
        "anchor": "Polarization rotation and the electrocaloric effect in barium titanate: We study the electrocaloric effect in the classic ferroelectric BaTiO3\nthrough a series of phase transitions driven by applied electric field and\ntemperature. We find both negative and positive electrocaloric effects, with\nthe negative electrocaloric effect, where temperature decreases with applied\nfield, in monoclinic phases. Macroscopic polarization rotation is evident\nthrough the monoclinic and orthorhombic phases under applied field, and is\nresponsible for the negative electrocaloric effect.",
        "positive": "Photo-thermoelectric properties and their use in study of transport\n  properties of both carriers from a single bulk sample: We describe a theory on photo-thermoelectric properties of a semiconductor,\nwhich include photo-conductivity, photo-Seebeck coefficient, and photo-Hall\neffect. We demonstrate that these properties provide a powerful tool for the\nstudy of carrier transport in semiconductors. Even though photo-carrier\ngeneration is a complicated process which often prohibits quantitative analysis\nas their species or numbers are not known. Using bulk samples seems even less\nlikely as the photo-carrier only affect a thin layer. Our method will allow\nresearchers to bypass these difficulties, to use only measured properties and\ndetermine both electron and hole mobilities as well as the ratio between\nelectrons and holes from a bulk sample. We provide initial experiment\nverification of our theory in the end using two distinctively different\nsemiconductors."
    },
    {
        "anchor": "Unveiling the mystery of nucleation and growth of carbon nanotube and\n  layered graphene inside carbon arc-discharge: A model for the formation of carbon nanotubes (CNTs) and layered graphene in\nan arc discharge method is developed on the basis of observed erosion of\ngraphite anode under various experimental conditions and analyses of the\nmorphology of the eroded anode-surface, concerned cathode deposits and their\nconstituents. It is predicted that, cold thermal shock, triggered by the rapid\nmovement of the anode-spot, leads to crack microbranching at some selected\nlocations on the anode-surface. These crack-microbranches cleave and fragment\nthe basal planes of pairs of adjacent crystallites into curved graphitic\nnanoribbons with minimum two basal planes. These nanoribbons further react\nchemically with the C2 and C3 precursors present in the dusty carbon plasma and\nevolve either in the form of CNT or layered-graphene, depending on the\nviscosity and composition of the gaseous environment they are exposed to, just\nafter getting detached from the anode.",
        "positive": "Asymptotic Homogenization in the Determination of Effective Intrinsic\n  Magnetic Properties of Composites: We present a computational framework for two-scale asymptotic homogenization\nto determine the intrinsic magnetic permeability of composites. To this end,\nconsidering linear magnetostatics, both vector and scalar potential\nformulations are used. Our homogenization algorithm for solving the cell\nproblem is based on the displacement method presented in Lukkassen et al. 1995,\nComposites Engineering, 5(5), 519-531. We propose the use of the meridional\neccentricity of the permeability tensor ellipsoid as an anisotropy index\nquantifying the degree of directionality in the linear magnetic response. As\napplication problems, 2D regular and random microstructures with overlapping\nand nonoverlapping monodisperse disks, all of which are periodic, are\nconsidered. We show that, for the vanishing corrector function, the derived\neffective magnetic permeability tensor gives the (lower) Reuss and (upper)\nVoigt bounds with the vector and scalar potential formulations, respectively.\nOur results with periodic boundary conditions show an excellent agreement with\nanalytical solutions for regular composites, whereas, for random heterogeneous\nmaterials, their convergence with volume element size is fast. Predictions for\nmaterial systems with monodisperse overlapping disks for a given inclusion\nvolume fraction provide the highest magnetic permeability with the most\nincreased inclusion interaction. In contrast, the disk arrangements in regular\nsquare lattices result in the lowest magnetic permeability and inadequate\ninclusion interaction. Such differences are beyond the reach of the isotropic\neffective medium theories, which use only the phase volume fraction and shape\nas mere statistical microstructural descriptors."
    },
    {
        "anchor": "Two-dimensional charge order stabilized in clean polytype\n  heterostructures: Compelling evidence suggests distinct correlated electron behavior may exist\nonly in clean 2D materials such as 1T-TaS2. Unfortunately, experiment and\ntheory suggest that extrinsic disorder in free standing 2D layers disrupts\ncorrelation-driven quantum behavior. Here we demonstrate a route to realizing\nfragile 2D quantum states through endotaxial polytype engineering of van der\nWaals materials. The true isolation of 2D charge density waves (CDWs) between\nmetallic layers stabilizes commensurate long-range order and lifts the coupling\nbetween neighboring CDW layers to restore mirror symmetries via interlayer CDW\ntwinning. The twinned-commensurate charge density wave (tC-CDW) reported herein\nhas a single metal--insulator phase transition at ~350 K as measured\nstructurally and electronically. Fast in-situ transmission electron microscopy\nand scanned nanobeam diffraction map the formation of tC-CDWs. This work\nintroduces endotaxial polytype engineering of van der Waals materials to access\nlatent 2D ground states distinct from conventional 2D fabrication.",
        "positive": "Large-angle, gigahertz-rate random telegraph switching induced by\n  spin-momentum transfer: We show that spin-polarized dc current passing through a small magnetic\nelement induces two-state, random telegraph switching of the magnetization via\nthe spin-momentum transfer effect. The resistances of the states differ by up\nto 50% of the change due to complete magnetization reversal. Fluctuations are\nseen for a wide range of currents and magnetic fields, with rates that can\nexceed 2 GHz, and involve collective motion of a large volume (10^4 nm^3) of\nspins. Switching rate trends with field and current indicate that increasing\ntemperature alone cannot explain the dynamics. The rates approach a stochastic\nregime wherein dynamics are governed by both precessional motion and thermal\nperturbations."
    },
    {
        "anchor": "Isotropic three-dimensional left-handed meta-materials: We investigate three-dimensional left-handed and related meta-materials based\non a fully symmetric multi-gap single-ring SRR design and crossing continuous\nwires. We demonstrate isotropic transmission properties of a SRR-only\nmeta-material and the corresponding left-handed material which possesses a\nnegative effective index of refraction due to simultaneously negative effective\npermeability and permittivity. Minor deviations from complete isotropy are due\nto the finite thickness of the meta-material.",
        "positive": "Two-Dimensional Magnetic Boron: We predict a two-dimensional (2D) antiferromagnetic (AFM) boron (designated\nas M-boron) by using ab initio evolutionary methodology. M-boron is entirely\ncomposed of B20 clusters in a hexagonal arrangement. Most strikingly, the\nhighest valence band of M-boron is isolated, strongly localized, and quite\nflat, which induces spin polarization on each cap of the B20 cluster. This flat\nband originates from the unpaired electrons of the capping atoms, and is\nresponsible for magnetism. M-boron is thermodynamically metastable and is the\nfirst cluster-based 2D magnetic material in the elemental boron system."
    },
    {
        "anchor": "Strain and Band-Gap Engineering in Ge-Sn Alloys via P Doping: Ge with a quasi-direct band gap can be realized by strain engineering,\nalloying with Sn, or ultrahigh n-type doping. In this work, we use all three\napproaches together to fabricate direct-band-gap Ge-Sn alloys. The heavily\ndoped n-type Ge-Sn is realized with CMOS-compatible nonequilibrium material\nprocessing. P is used to form highly doped n-type Ge-Sn layers and to modify\nthe lattice parameter of P-doped Ge-Sn alloys. The strain engineering in\nheavily-P-doped Ge-Sn films is confirmed by x-ray diffraction and micro Raman\nspectroscopy. The change of the band gap in P-doped Ge-Sn alloy as a function\nof P concentration is theoretically predicted by density functional theory and\nexperimentally verified by near-infrared spectroscopic ellipsometry. According\nto the shift of the absorption edge, it is shown that for an electron\nconcentration greater than 1x10^20 cm-3 the band-gap renormalization is\npartially compensated by the Burstein-Moss effect. These results indicate that\nGe-based materials have high potential for use in near-infrared optoelectronic\ndevices, fully compatible with CMOS technology.",
        "positive": "Constructing phase diagrams for defects by correlated atomic-scale\n  characterization: Phase transformations and crystallographic defects are two essential tools to\ndrive innovations in materials. Bulk materials design via tuning chemical\ncompositions has been systematized using phase diagrams. We show here that the\nsame thermodynamic concept can be applied to understand the chemistry at\ndefects. We present a combined experimental and modelling approach to scope and\nbuild phase diagrams for defects. The discovery was enabled by triggering phase\ntransformations of individual defects through local alloying, and sequentially\nimaging the structural and chemical changes using atomic-resolution scanning\ntransmission electron microscopy. By observing atomic-scale phase\ntransformations of a Mg grain boundary through Ga alloying, we exemplified the\nmethod to construct a grain boundary phase diagram using ab initio simulations\nand thermodynamic principles. The methodology enables a systematic development\nof defect phase diagrams to propel a new paradigm for materials design\nutilizing chemical complexity and phase transformations at defects."
    },
    {
        "anchor": "Orbital degree of freedom in high entropy oxides: The spin, charge, and lattice degrees of freedom and their interplay in high\nentropy oxides were intensively investigated in recent years. However, how the\norbital degree of freedom is affected by the extreme disorder in high entropy\noxides hasn't been studied. In this work, using perovskite structured\n\\textit{R}VO$_3$ as a materials playground, we report how the disorder arising\nfrom mixing different rare earth ions at the rare earth site affects the\norbital ordering of V$^{3+}$ t$_{2g}$-electrons. Since each member of\n\\textit{R}VO$_3$ crystallizes into the same orthorhombic \\textit{Pbnm}\nstructure, the configurational entropy should not be critical for the success\nsynthesis of (\\textit{R}$_1$,...,\\textit{R}$_n$)VO$_3$. The spin and orbital\nordering was studied by measuring magnetic properties and specific heat of\nsingle crystals. Rather than the number and type of rare earth ions, the\naverage ionic radius and size variance are the key factors determining the spin\nand orbital order in (\\textit{R}$_1$,...,\\textit{R}$_n$)VO$_3$. When the size\nvariance is small, the average ionic radius takes precedence in dictating spin\nand orbital order. Increasing size variance suppresses the G-type orbital order\nand C-type magnetic order but favors the C-OO/G-AF state and the spin-orbital\nentanglement. These findings suggest that the extreme disorder introduced by\nmixing multiple rare earth ions in high entropy perovskites might be employed\nto preserve the orbital degree of freedom to near the magnetic ordering\ntemperature, which is necessary for the electronic driven orbital ordering in a\nKugel-Khomskii compound.",
        "positive": "Two-dimensional germanium islands with Dirac signature on Ag2Ge surface\n  alloy: Two-dimensional (2D) Dirac materials have attracted intense research efforts\ndue to their promise for applications ranging from field-effect transistors and\nlow-power electronics to fault-tolerant quantum computation. One key challenge\nis to fabricate 2D Dirac materials hosting Dirac electrons. Here, monolayer\ngermanene is successfully fabricated on a Ag2Ge surface alloy. Scanning\ntunneling spectroscopy measurements revealed a linear energy dispersion\nrelation. The latter was supported by density functional theory calculations.\nThese results demonstrate that monolayer germanene can be realistically\nfabricated on a Ag2Ge surface alloy. The finding opens the door to exploration\nand study of 2D Dirac material physics and device applications."
    },
    {
        "anchor": "Measurement of Ehrlich-Schwoebel barrier contribution to the\n  self-organized formation of ordered surface patterns on Ge(001): Normal incidence 1 keV Ar$^+$ ion bombardment leads to amorphization and\nultrasmoothing of Ge at room temperature, but at elevated temperatures the Ge\nsurface remains crystalline and is unstable to the formation of self-organized\nnanoscale patterns of ordered pyramid-shaped pits. The physical phenomenon\ndistinguishing the high temperature patterning from room temperature\nultrasmoothing is believed to be a surface instability due to the\nEhrlich-Schwoebel barrier for diffusing vacancies and adatoms, which is not\npresent on the amorphous material. This real-time GISAXS study compares\nsmoothing of a pre-patterned Ge sample at room temperature with patterning of\nan initially flat Ge sample at an elevated temperature. In both experiments,\nwhen the nanoscale structures are relatively small in height, the average\nkinetics can be explained by a linear theory. The linear theory coefficients,\nindicating surface stability or instability, were extracted for both\nexperiments. A comparison between the two measurements allows estimation of the\ncontribution of the Ehrlich-Schwoebel barrier to the self-organized formation\nof ordered nanoscale patterns on crystalline Ge surfaces.",
        "positive": "Vertical Strain-Induced Modification of the Electrical and Spin\n  Properties of Monolayer MoSi2X4 (X= N, P, As and Sb): In this work, the electrical and spin properties of monolayer MoSi2X4 (X= N,\nP, As, and Sb) under vertical strain are investigated. The band structures\nstate that MoSi2N4 is an indirect semiconductor, whereas other compounds are\ndirect semiconductors. The vertical strain has been selected to modify the\nelectrical properties. The bandgap shows a maximum and decreases for both\ntensile and compressive strains. The valence band at K-point displays a large\nspin-splitting, whereas the conduction band has a negligible splitting. On the\nother hand, the second conduction band has a large spin-splitting and moves\ndown under vertical strain which leads to a large spin-splitting in both\nconduction and valence bands edges. The projected density of states along with\nthe projected band structure clarifies the origin of these large\nspin-splittings. These three spin-splittings can be controlled by vertical\nstrain."
    },
    {
        "anchor": "Charge-State Stabilization of Neutral Group-IV Impurity-Vacancy Color\n  Centers in Hydrogen-Terminated Diamond: Charge-state stabilization of the neutral group-IV impurity-vacancy color\ncenters in diamond has thus far proved difficult to achieve reliably. The\nneutral group-IV color centers, however, provide a robust alternative to the\nNV$^-$ center in diamond given their inversion symmetry which renders them less\nsusceptible to spectral diffusion. In this work, we show that the ratio for the\noccurrences of SiV$^0$ in hydrogen-terminated and oxygen-terminated diamond\n[see Zi-Huai Zhang et al., Phys. Rev. Lett. 130, 166902 (2023)] can be\naccurately estimated from knowledge of the surface levels for the two\nterminations and we propose adsorption of halogens on diamond to further\nenhance the occurrence of SiV$^0$. We leverage the notion presented in our\nearlier work [see Rodrick Kuate Defo et al. Phys. Rev. B 108, 235208 (2023)]\nthat surface defects can modulate the donor levels of near-surface point\ndefects to determine the influence of surface termination on the production of\nSi$V^0$, and we additionally further elaborate our earlier work's\ncarrier-capture formalism.",
        "positive": "Superatom Orbitals, Orbital Splitting and Structure Prediction of Pure\n  Alkali Metal Clusters: Jellium model achieved great success in predicting stable clusters with\nclosed electronic shells and zero spin. In order to explain the stability of\nopen shell clusters, it is necessary to consider the case of non-degenerate\nenergy levels. In this paper the energy levels in nine low-lying Li$_{19}$\nclusters are analysed systematically through superatomic orbital splitting\neffect. It is found that for originally degenerate orbitals like five 1D\norbitals, the more the orbital extends in the direction of the cluster\nextension, the lower the energy of the orbital becomes. So oblate Li$_{19}$\nclusters have the orbital sequence of\n$1\\mathrm{S}^2-1\\mathrm{P}_{x/y}^{4}-1\\mathrm{P}_{z}^{2}-1\\mathrm{D}_{xy/x^2-y^2}^{4}-2\\mathrm{S}^2-1\\mathrm{D}_{xz/yz}^{4}-1\\mathrm{D}_{z^2}^{1}$,\nwhile prolate Li$_{19}$ clusters have the sequence of\n$1\\mathrm{S}^2-1\\mathrm{P}_{z}^{2}-1\\mathrm{P}_{x/y}^{4}-1\\mathrm{D}_{z^2}^{2}-1\\mathrm{D}_{xz/yz}^{4}-1\\mathrm{D}_{xy/x^2-y^2}^{4}-2\\mathrm{S}^1$.\nThis electron configuration is applied to predict the shape and magnetic moment\nof the alkali metal Li$_{n}$ clusters. The stability of the Li$_{14}$ cluster\ncan be successfully interpreted in the framework of orbital splitting effect\nwithout resorting to the super valence bond (SVB) model, indicating a\nnon-spherical cluster can achieve good stability without meeting the magic\nnumber. It is also proposed that the orbital splitting can be used to predict\nthe shape (prolate, oblate or sphere) and magnetic moment of clusters. 11 out\nof 16 predicted shapes of Li$_n(n=3-18)$ are consistent with the results\nobtained by the principle of minimum energy."
    },
    {
        "anchor": "Quantum-well states and discontinuities in opto-electrical\n  characteristics of SCH lasers: Computer simulations with Synopsys' Sentaurus TCAD of opto-electrical\ncharacteristics of separate-confinement heterostructure laser based on AlGaAs\nare used as an example to study the role of the width and depth of Quantum Well\n(QW) active region on laser characteristics, I-V and I-L, below and above the\nlasing threshold. The device properties depend on both, the number of bound QW\nstates and on closeness of the highest bound states to conduction or valence\nband offset. The lasing action may not exist at certain widths or hights of QW,\nthe threshold current is a discontinuous function of these parameters. The\neffects are more pronounced at low temperatures. Discontinuities in\ncharacteristics may be observed at certain conditions in temperature\ndependencies of laser parameters.",
        "positive": "A comparison of Monte-Carlo simulations using RESTRAX and McSTAS with\n  experiment on IN14: Monte-Carlo simulations of a focusing supermirror guide after the\nmonochromator on the IN14 cold neutron three-axis spectrometer, I.L.L. were\ncarried out using the instrument simulation programs RESTRAX and McSTAS. The\nsimulations were compared to experiment to check their accuracy. Comparisons of\nthe flux ratios over both a 100 mm2 and a 1600 mm2 area at the sample position\ncompare well, and there is very close agreement between simulation and\nexperiment for the energy spread of the incident beam."
    },
    {
        "anchor": "Van der Waals stacked multilayer in-plane graphene/hexagonal boron\n  nitride heterostructure: its interfacial thermal transport properties: Combining both vertical and in-plane two-dimensional (2D) heterostructures\nopens up the possibility to create an unprecedented architecture using 2D\natomic layer building blocks. The thermal transport properties of such mixed\nheterostructures, critical to various applications in nanoelectronics, however,\nhave not been thoroughly explored. Herein, we construct two configurations of\nmultilayer in-plane graphene/hexagonal boron nitride (Gr/h-BN) heterostructures\n(i.e. mixed heterostructures) via weak van der Waals (vdW) interactions and\nsystematically investigate the dependence of their interfacial thermal\nconductance (ITC) on the number of layers using non-equilibrium molecular\ndynamics (NEMD) simulations. The computational results show that the ITC of two\nconfigurations of multilayer in-plane Gr/h-BN heterostructures (MIGHHs)\ndecrease with increasing layer number n and both saturate at n = 3. And\nsurprisingly, we find that the MIGHH is more advantageous to interfacial\nthermal transport than the monolayer in-plane Gr/h-BN heterostructure, which is\nin strong contrast to the commonly held notion that the multilayer structures\nof Gr and h-BN suppress the phonon transmission. The underlying physical\nmechanisms for these puzzling phenomena are probed through the analyses of heat\nflux, temperature jump, stress concentration factor, overlap of phonon\nvibrational spectra and phonon participation ratio. In particular, by changing\nthe stacking angle of MIGHH, a higher ITC can be obtained due to the thermal\nrectification behavior. Furthermore, we find that the ITC in MIGHH can be\nwell-regulated by controlling the coupling strength between layers. Our\nfindings here are of significance for understanding the interfacial thermal\ntransport behaviors of multilayer in-plane Gr/h-BN heterostructure, and are\nexpected to attract extensive interest in exploring its new physics and\napplications.",
        "positive": "E-Beam Induced Micropattern Generation and Amorphization of\n  L-Cysteine-Functionalized Graphene Oxide Nano-composites: The evolution of dynamic processes in graphene-family materials are of great\ninterest for both scientific purposes and technical applications. Scanning\nelectron microscopy and transmission electron microscopy outstand among the\ntechniques that allow both observing and controlling such dynamic processes in\nreal time. On the other hand, functionalized graphene oxide emerges as a\nfavorable candidate from graphene-family materials for such an investigation\ndue to its distinctive properties, that encompass a large surface area, robust\nthermal stability, and noteworthy electrical and mechanical properties after\nits reduction. Here, we report on studies of surface structure and adsorption\ndynamics of L-Cysteine on electrochemically exfoliated graphene oxides basal\nplane. We show that electron beam irradiation prompts an amorphization of\nfunctionalized graphene oxide along with the formation of micropatterns of\ncontrolled geometry composed of L-Cysteine-Graphene oxide nanostructures. The\ncontrolled growth and predetermined arrangement of micropatterns as well as\ncontrolled structure disorder induced by e beam amorphization, in its turn\npotentially offering tailored properties and functionalities paving the way for\npotential applications in nanotechnology, sensor development, and surface\nengineering. Our findings demonstrate that graphene oxide can cover L-Cysteine\nin such a way to provide a control on the positioning of emerging\nmicrostructures about 10-20 um in diameter. Besides, Raman and SAED measurement\nanalyses yield above 50% amorphization in a material. The results of our\nstudies demonstrate that such a technique enables the direct creation of\nmicropatterns of L-Cysteine-Graphene oxide eliminating the need for complicated\nmask patterning procedures."
    },
    {
        "anchor": "Suppression of the low-temperature phase-separated state under pressure\n  in (Eu$_{1-x}$Gd$_{x}$)$_{0.6}$Sr$_{0.4}$MnO$_{3}$ ($x=0,0.1$): We have demonstrated the effect of pressure on the steplike metamagnetic\ntransition and its associated magnetostriction in\n(Eu$_{1-x}$Gd$_{x}$)$_{0.6}$Sr$_{0.4}$MnO$_{3}$ ($x=0$ and 0.1). The critical\nfield initiating the field induced ferromagnetic transition in both samples is\nlowered by the applied pressure. The further application of external pressure\nup to 1.2 GPa on the $x=0$ parent sample causes a spontaneous ferromagnetic\ntransition with a second-oder like character, leading to collapses of the\nsteplike transition and its concomitant lattice striction. These findings\nindicate a crucial role of the low-temperature phase separated state\ncharacterized by a suppressed magnetization upon decreasing temperature.",
        "positive": "Accurate Prediction of Bonding Properties by A Machine Learning-based\n  Model using Isolated States Before Bonding: Given the strong dependence of material structure and properties on the\nlength and strength of constituent bonds and the fact that surface adsorption\nand chemical reactions are initiated by the formation of bonds between two\nsystems, bonding parameters are of key importance for material design and\nindustrial processes. In this study, a machine learning (ML)-based model is\nused to accurately predict bonding properties from information pertaining to\nisolated systems before bonding. This model employs the density of states (DOS)\nbefore bond formation as the ML descriptor and accurately predicts binding\nenergy, bond distance, covalent electron amount, and Fermi energy even when\nonly 20% of the whole dataset is used for training. The results show that the\nDOS of isolated systems before bonding is a powerful descriptor for the\naccurate prediction of bonding and adsorption properties."
    },
    {
        "anchor": "GaMnN epitaxial films with high magnetization: We report on the fabrication of pseudomorphic wurtzite GaMnN grown on GaN\nwith Mn concentrations up to 10% using molecular beam epitaxy. According to\nRutherford backscattering the Mn ions are mainly at the Ga-substitutional\npositions, and they are homogeneously distributed according to depth-resolved\nAuger-electron spectroscopy and secondary-ion mass-spectroscopy measurements. A\nrandom Mn distribution is indicated by transmission electron microscopy, no\nMn-rich clusters are present for optimized growth conditions. A linear increase\nof the c-lattice parameter with increasing Mn concentration is found using\nx-ray diffraction. The ferromagnetic behavior is confirmed by superconducting\nquantum-interference measurements showing saturation magnetizations of up to\n150 emu/cm^3.",
        "positive": "Non-Eulerian behavior of graphitic materials under compression: The mechanical behavior of graphitic materials is greatly affected by the\nweak interlayer bonding with van der Waals forces for a range of thickness from\nnano to macroscale. Herein, we present a comprehensive study of the effect of\nlayer thickness on the compression behavior of graphitic materials such as\ngraphene which are fully embedded in polymer matrices. Raman Spectroscopy was\nemployed to identify experimentally the critical strain to failure of the\ngraphitic specimens. The most striking finding is that, contrary to what would\nbe expected from Eulerian mechanics, the critical compressive strain to failure\ndecreases with increase of flake thickness. This is due to the layered\nstructure of the material and in particular the weak cohesive forces that hold\nthe layers together. The plate phenomenology breaks down for the case of\nmulti-layer graphene, which can be approached as discrete single layers weakly\nbonded to each other. This behavior is modelled here by considering the\ninterlayer bonding (van der Waals forces) as springs in series, and very good\nagreement was found between theory and experiment. Finally, it will be shown\nthat in the post failure regime multi-layer graphenes exhibit negative\nstiffness and thus behave as mechanical metamaterials."
    },
    {
        "anchor": "A Charge-Density-Wave Topological Semimetal: Topological physics and strong electron-electron correlations in quantum\nmaterials are typically studied independently. However, there have been rapid\nrecent developments in quantum materials in which topological phase transitions\nemerge when the single-particle band structure is modified by strong\ninteractions. We here demonstrate that the room-temperature phase of\n(TaSe$_4$)$_2$I is a Weyl semimetal with 24 pairs of Weyl nodes. Owing to its\nquasi-1D structure, (TaSe$_4$)$_2$I hosts an established CDW instability just\nbelow room temperature. Using X-ray diffraction, angle-resolved photoemission\nspectroscopy, and first-principles calculations, we find that the CDW in\n(TaSe$_4$)$_2$I couples the bulk Weyl points and opens a band gap. The\ncorrelation-driven topological phase transition in (TaSe$_4$)$_2$I provides a\nroute towards observing condensed-matter realizations of axion electrodynamics\nin the gapped regime, topological chiral response effects in the semimetallic\nphase, and represents an avenue for exploring the interplay of correlations and\ntopology in a solid-state material.",
        "positive": "Exciton-plasmon states in nanoscale materials: breakdown of the\n  Tamm-Dancoff approximation: Within the Tamm-Dancoff approximation ab initio approaches describe excitons\nas packets of electron-hole pairs propagating only forward in time. However, we\nshow that in nanoscale materials excitons and plasmons hybridize, creating\nexciton--plasmon states where the electron-hole pairs oscillate back and forth\nin time. Then, as exemplified by the trans-azobenzene molecule and carbon\nnanotubes, the Tamm-Dancoff approximation yields errors as large as the\naccuracy claimed in ab initio calculations. Instead, we propose a general and\nefficient approach that avoids the Tamm--Dancoff approximation, and correctly\ndescribes excitons, plasmons and exciton-plasmon states."
    },
    {
        "anchor": "Anisotropy driven ultrafast nanocluster burrowing: We explore the occurrence of low-energy and low-temperature transient cluster\nburrowing leading to intact cluster inclusions. In particular, the anomalously\nfast (ballistic) Pt nanocluster implantation into Al and Ti substrates has been\nfound by molecular dynamics simulations using a tight-binding many-body\npotential with the 1-5 eV/atom low impact energy. Similar behavior has also\nbeen found for many other cluster/substrate couples such as Cu/Al and Ni/Ti,\nCo/Ti, etc. In particular, in Ni/Ti at already $\\sim 0.5$ eV/atom impact energy\nburrowing takes place. At this few eV/atom low impact energy regime instead of\nthe expected stopping at the surface we find the propagation of the cluster\nthrough a thin Al slab as thick as $\\sim 50$ $\\hbox{\\AA}$ with a nearly\nconstant speed ($\\propto 1$ eV/atom). Hence the cluster moves far beyond the\nrange of the impact energy which suggests that the mechanism of cluster\nburrowing can not be explained simply by collisional cascade effects. In the\ncouples with reversed succession (e.g. Ti/Pt, Al/Pt) no burrowing has been\nfound, the clusters remain on the surface (the asymmetry of burrowing). We\nargue that cluster penetration occurs at few eV/atom impact energy when the\ncluster/substrate interaction is size-mismatched and mass anisotropic\natomically.",
        "positive": "Neural Network Interatomic Potentials For Open Surface Nano-mechanics\n  Applications: Material characterization in nano-mechanical tests requires precise\ninteratomic potentials for the computation of atomic energies and forces with\nnear-quantum accuracy. For such purposes, we develop a robust neural-network\ninteratomic potential (NNIP), and we provide a test for the example of\nmolecular dynamics (MD) nanoindentation, and the case of body-centered cubic\ncrystalline molybdenum (Mo). We employ a similarity measurement protocol, using\nstandard local environment descriptors, to select ab initio configurations for\nthe training dataset that capture the behavior of the indented sample. We find\nthat it is critical to include generalized stacking fault (GSF) configurations,\nfeaturing a dumbbell interstitial on the surface, to capture dislocation cores,\nand also high-temperature configurations with frozen atom layers for the\nindenter tip contact. We develop a NNIP with distinct dislocation nucleation\nmechanisms, realistic generalized stacking fault energy (GSFE) curves, and an\ninformative energy landscape for the atoms on the sample surface during\nnanoindentation. We compare our NNIP results with nanoindentation simulations,\nperformed with three existing potentials -- an embedded atom method (EAM)\npotential, a gaussian approximation potential (GAP), and a tabulated GAP\n(tabGAP) potential -- that predict different dislocation nucleation mechanisms,\nand display the absence of essential information on the shear stress at the\nsample surface in the elastic region. We believe that these features render\nspecialized NNIPs essential for simulations of nanoindentation and\nnano-mechanics with near-quantum accuracy."
    },
    {
        "anchor": "Interplay between charge-order, ferroelectricity and ferroelasticity:\n  tungsten bronze structures as a playground for multiferroicity: Large electron-electron Coulomb-interactions in correlated systems can lead\nto a periodic arrangement of localized electrons, the so called \"charge-order\".\nThe latter is here proposed as a driving force behind ferroelectricity in iron\nfluoride K0.6FeF3. By means of density functional theory, we propose different\nnon-centrosymmetric d5/d6 charge-ordering patterns, each giving rise to\npolarization along different crystallographic axes and with different\nmagnitudes. Accordingly, we introduce the concept of \"ferroelectric anistropy\"\n(peculiar to improper ferroelectrics with polarization induced by electronic\ndegrees of freedom), denoting the small energy difference between competing\ncharge-ordered states that might be stabilized upon electrical field-cooling.\nMoreover, we suggest a novel type of charge-order-induced ferroelasticity:\nfirst-principles simulations predict a monoclinic distortion to be driven by a\nspecific charge-ordering pattern, which, in turn, unambiguously determines the\ndirection of ferroelectric polarization. K0.6FeF3 therefore emerges as a\nprototypical compound, in which the intimately coupled electronic and\nstructural degrees of freedom result in a manifest and peculiar\nmultiferroicity.",
        "positive": "Carrier Multiplication-Induced Structural Change during Ultrafast\n  Carrier Relaxation and Non-Thermal Phase Transition in Semiconductors: While being extensively studied as an important physical process to alter\nexciton population in nanostructures at fs time scale, carrier multiplication\nhas not been considered seriously as a major mechanism for phase transition.\nReal-time time-dependent density functional theory study of Ge2Sb2Te5 reveals\nthat carrier multiplication can induce ultrafast phase transition in solid\nstate despite that the lattice remains cold. The results also unify the\nexperimental findings in other semiconductors for which the explanation remains\nto be the 30-year old phenomenological plasma annealing model."
    },
    {
        "anchor": "A pseudo-binary interdiffusion study in the beta-Ni(Pt)Al phase: Interdiffusion study is conducted in the Ni-rich part of the beta-Ni(Pt)Al\nphase following the pseudo-binary approach. Interdiffusion coefficients over\nthe whole composition range considered in this study increases with the\nincrease in Pt content, which is in line with the theoretical study predicting\nthe decrease in vacancy formation and migration energy because of Pt addition.\nThe trend of change in diffusion coefficient with the increase in Ni and Pt\ncontent indicates that Pt preferably replaces Ni antisites.",
        "positive": "Enhanced in-plane ferroelectricity, antiferroelectricity, and\n  unconventional 2D emergent fermions in QL-XSbO$_2$ (X= Li, Na): Low-dimensional ferroelectricity and Dirac materials with protected band\ncrossings are fascinating research subjects. Based on first-principles\ncalculations, we predict the coexistence of spontaneous in-plane polarization\nand novel 2D emergent fermions in dynamically stable quadruple-layer (QL)\nXSbO$_2$ (X= Li, Na). Depending on the different polarization configurations,\nQL-XSbO$_2$ can exhibit unconventional inner-QL ferroelectricity and\nantiferroelectricity. Both ground states harbor robust ferroelectricity with\nenhanced spontaneous polarization of 0.56 nC/m and 0.39 nC/m for QL-LiSbO$_2$\nand QL-NaSbO$_2$, respectively. Interestingly, the QL-LiSbO$_2$ possesses two\nother metastable ferroelectric (FE) phases, demonstrating the first 2D example\nwith multiple FE orders. The ground FE phase can be flexibly driven into one of\nthe two metastable FE phases and then into the antiferroelectric (AFE) phase.\nDuring this phase transition, several types of 2D fermions emerge, for\ninstance, hourglass hybrid and type-II Weyl loops in the ground FE phase,\ntype-II Weyl fermions in the metastable FE phase, and type-II Dirac fermions in\nthe AFE phase. These 2D fermions are robust under spin-orbit coupling. Notably,\ntwo of these fermions, e.g., an hourglass hybrid or type-II Weyl loop, have not\nbeen observed before. Our findings identify QL-XSbO$_2$ as a unique platform\nfor studying 2D ferroelectricity relating to 2D emergent fermions."
    },
    {
        "anchor": "Combining advanced photoelectron spectroscopy approaches to analyse\n  deeply buried GaP(As)/Si(100) interfaces: Interfacial chemical states and\n  complete band energy diagrams: The epitaxial growth of the polar GaP(100) on the nonpolar Si(100) substrate\nsuffers from inevitable defects at the antiphase domain boundaries, resulting\nfrom mono-atomic steps on the Si(100) surface. Stabilization of Si(100)\nsubstrate surfaces with arsenic is a promising technological step enabling the\npreparation of Si substrates with double atomic steps and reduced density of\nthe APDs. In this paper, 4-50 nm thick GaP epitaxial films were grown on\nAs-terminated Si(100) substrates with different types of doping, miscuts, and\nAs-surface termination by metalorganic vapor phase epitaxy. The GaP(As)/Si(100)\nheterostructures were investigated by X-ray photoelectron spectroscopy (XPS)\ncombined with gas cluster ion beam (GCIB) sputtering and by hard X-ray\nphotoelectron spectroscopy (HAXPES). We found residuals of arsenic atoms in the\nGaP lattice (0.2-0.3 at.%) and a localization of As atoms at the\nGaP(As)/Si(100) interface (1 at.%). Deconvolution of core level peaks revealed\ninterface core level shifts. In As core levels, chemical shifts between 0.5-0.8\neV were measured and identified by angle-resolved XPS measurements. Similar\nvalence band offset (VBO) values of 0.6 eV were obtained, regardless of the\ndoping type of Si substrate, Si substrate miscut or type of As-terminated Si\nsubstrate surface. The band alignment diagram of the heterostructure was\ndeduced.",
        "positive": "Visualizing influence of point defects on electronic band structure of\n  graphene: The supercell approach enables us to treat the electronic structure of\ndefective crystals, but the calculated energy bands are too complicated to\nunderstand or to compare with angle-resolved photoemission spectra because of\ninevitable zone folding. We discuss how to visualize supercell band structures\nmore effectively by incorporating in them unfolded spectral weights and orbital\ndecompositions. We then apply these ideas to gain a better understanding of the\nband structure of graphene containing various types of points defects,\nincluding nitrogen impurity, hydrogen adsorbate, and vacancy defect, and also\nthe Stone-Wales defect."
    },
    {
        "anchor": "Revised crystal structure model of Li2NH by neutron powder diffraction: We performed neutron powder diffraction experiments on lithium imide Li2NH,\nand have proposed a revised crystal structure model. Li2NH has a face-centered\ncubic structure with a partially occupied hydrogen site. Of the possible\ncrystal structure models that represent the obtained data, the model with F-43m\nsymmetry having hydrogen atoms at the 16e site, in which only one hydrogen atom\nrandomly occupies one of the four hydrogen positions around a nitrogen atom, is\nmost probable. For this model, the distance between the nearest nitrogen and\nhydrogen atoms is 0.82(6)A, and the angle between H-N-H is 109.5deg., which are\nclose to those of the lithium amide LiNH2, indicating that the structural\ncircumstances around nitrogen and hydrogen are similar in Li2NH and LiNH2.",
        "positive": "Magnetism and electronic properties of BiFeO3 under lower pressure: Ab initio calculations show an antiferromagnetic-ferromagnetic phase\ntransition around 9-10 GPa and a magnetic anomaly at 12 GPa in BiFeO3. The\nmagnetic phase transition also involves a structural and insulator-metal\ntransition. The G-type AFM configuration under pressure leads to an increase of\nthe y component and decrease of the z component of the magnetization, which is\ncaused by the splitting of the dz2 orbital from doubly degenerate eg states.\nOur results agree with recent experimental results."
    },
    {
        "anchor": "Charging/discharging mechanism in Mg3Bi2 anode for Mg-ion batteries; The\n  role of the spin-orbit coupling: Using density functional calculations, we examine insertion/extraction of Mg\nions in Mg3Bi2, an interesting Mg-ion battery anode. We found that a (1 1 0)\nfacet is the most stable termination. Vacating a Mg2+ ion from the octahedral\nsite is more favourable for both surface and bulk regions of the material.\nHowever, the diffusion barriers among the tetrahedral sites are around 3 times\nsmaller than those among octahedral sites. Consequently, during the\nmagnesiation/demagnesiation process, Mg ions first vacate the octahedral sites\nand then diffuse through the tetrahedral sites. The spin-orbit interaction\nlowers Mg's vacancy formation energy but has a minor effect on diffusion\nbarriers.",
        "positive": "$\\textit{Ab Initio}$ Theory of the Impact from Grain Boundaries and\n  Substitutional Defects on Superconducting Nb$_3$Sn: Grain boundaries play a critical role in applications of superconducting\nNb$_3$Sn: in dc applications, grain boundaries preserve the material's\ninherently high critical current density by pinning flux, while in ac\napplications grain boundaries can provide weak points for flux entry and lead\nto significant dissipation. We present the first $\\textit{ab initio}$ study to\ninvestigate the physics of different boundary types in Nb$_3$Sn using density\nfunctional theory. We identify an energetically favorable selection of tilt and\ntwist grain boundaries of distinct orientations. We find that clean grain\nboundaries free of point defects reduce the Fermi-level density of states by a\nfactor of two, an effect that decays back to the bulk electronic structure\n$\\sim1-1.5$ nm from the boundary. We further calculate the binding\nfree-energies of tin substitutional defects to multiple boundaries, finding a\nstrong electronic interaction that extends to a distance comparable to that of\nthe reduction of density of states. Associated with this interaction, we\ndiscover a universal trend in defect electronic entropies near a boundary. We\nprobe the effects of defect segregation on grain boundary electronic structure\nand calculate the impact of substitutional impurities on the Fermi-level\ndensity of states in the vicinity of a grain boundary, finding that titanium\nand tantalum have little impact regardless of placement, whereas tin, copper,\nand niobium defects each have a significant impact but only on sites away from\nthe boundary core. Finally, we consider how all of these effects impact the\nlocal superconducting transition temperature $T_\\textrm{c}$ as a function of\ndistance from the boundary plane."
    },
    {
        "anchor": "Effects of Reducing Heat Treatment on the Structural and the Magnetic\n  Properties of Mn:ZnO Ceramics: Polycrystalline bulk Mn:ZnO ceramics with Mn nominal concentrations of 6, 11,\n17 and 22 at.% were prepared trough solid-state reaction method and subjected\nto a heat treatment in reducing atmosphere (Ar (95%) and H2 (5%)). The samples\nwere studied with particular emphasis on their compositions, structural, and\nmagnetic properties. A detailed microstructural and chemical analysis confirms\nthe Mn doping of the wurtzite ZnO structure mainly at the surface of the ZnO\ngrains. For the samples with higher Mn content, the secondary phases ZnMn2O4\nand Mn1-xZnxO (Zn-doped MnO) were detected for the as prepared and the heat\ntreated samples, respectively. The structural change of the secondary phases\nunder heat treatment, from ZnMn2O4 to Mn1-xZnxO, confirms the effectiveness of\nthe heat treatment in to reduce the valence of the metallic ions and in the\nformation of oxygen vacancies into the system. In spite of the induced defects,\nthe magnetic analysis present only a paramagnetic behavior with an\nantiferromagnetic coupling between the Mn ions. In the context of the bound\nmagnetic polaron theory, it is concluded that oxygen vacancies are not the\nnecessary defect to promote the desired ferromagnetic order at room\ntemperature.",
        "positive": "Charge Transport in Organic Molecular Semiconductors from First\n  Principles: The Band-Like Hole Mobility in Naphthalene Crystal: Predicting charge transport in organic molecular crystals is notoriously\nchallenging. Carrier mobility calculations in organic semiconductors are\ndominated by quantum chemistry methods based on charge hopping, which are\nlaborious and only moderately accurate. We compute from first principles the\nelectron-phonon scattering and the phonon-limited hole mobility of naphthalene\ncrystal in the framework of ab initio band theory. Our calculations combine GW\nelectronic bandstructures, ab initio electron-phonon scattering, and the\nBoltzmann transport equation. The calculated hole mobility is in very good\nagreement with experiment between 100$-$300 K, and we can predict its\ntemperature dependence with high accuracy. We show that scattering between\ninter-molecular phonons and holes regulates the mobility, though\nintra-molecular phonons possess the strongest coupling with holes. We revisit\nthe common belief that only rigid molecular motions affect carrier dynamics in\norganic molecular crystals. Our work provides a quantitative and rigorous\nframework to compute charge transport in organic crystals, and is a first step\ntoward reconciling band theory and carrier hopping computational methods."
    },
    {
        "anchor": "Electronic and magnetic properties of 3$d$ transition-metal adatoms on\n  Mn/W(110): Using density functional theory, we investigate the electronic and magnetic\nproperties of $3d$ transition-metal adatoms adsorbed on a monolayer of Mn on\nW(110). Mn/W(110) has a noncollinear cycloidal spin-spiral ground state with an\nangle of 173$^\\circ$ between magnetic moments of adjacent Mn rows. It allows to\nrotate the spin orientation of an adsorbed magnetic adatom quasi-continuously.\nTherefore, this surface is ideally suited for manipulating the spin direction\nof individual atoms and exploring their magnetic properties using scanning\ntunneling microscopy (STM). The adsorbed V and Cr transition-metal adatoms\ncouple antiferromagnetically to the nearest neighbor Mn atom of Mn monolayer\nwhile Mn, Fe, Co, and Ni couple ferromagnetically. The magnetic moments of the\n$3d$ adatoms are large and show a Hund's rule type of trend with a peak in the\nmiddle of the series. We find large spin splitting of the $3d$ transition-metal\nadatoms, large spin polarization of the local vacuum density of states up to\n73\\% at the Fermi energy, and significant tunneling anisotropic\nmagnetoresistance enhancement up to 27\\%. We conclude that such large values\nstem from the strong hybridization between the adatoms and the Mn atoms of the\nmonolayer. Furthermore, identification of spin orientations of the adatom using\nspin-polarized STM is only possible for Co and V adatoms.",
        "positive": "Dimensionality-driven orthorhombic MoTe2 at room temperature: We use a combination of Raman spectroscopy and transport measurements to\nstudy thin flakes of the type-II Weyl semimetal candidate MoTe2 protected from\noxidation. In contrast to bulk crystals, which undergo a phase transition from\nmonoclinic to the inversion symmetry breaking, orthorhombic phase below ~250 K,\nwe find that in moderately thin samples below ~12 nm, a single orthorhombic\nphase exists up to and beyond room temperature. This could be due to the effect\nof c-axis confinement, which lowers the energy of an out-of-plane hole band and\nstabilizes the orthorhombic structure. Our results suggest that Weyl nodes,\npredicated upon inversion symmetry breaking, may be observed in thin MoTe2 at\nroom temperature."
    },
    {
        "anchor": "Thermal conductivity of ternary III-V semiconductor alloys: The role of\n  mass difference and long-range order: Thermal transport in bulk ternary III-V arsenide (III-As) semiconductor\nalloys was investigated using equilibrium molecular dynamics with optimized\nAlbe-Tersoff empirical interatomic potentials. Existing potentials for binary\nAlAs, GaAs, and InAs were optimized to obtain accurate phonon dispersions and\ntemperature-dependent thermal conductivity. Calculations of thermal transport\nin ternary III-Vs commonly employ the virtual-crystal approximation (VCA),\nwhere the structure is assumed to be a random alloy and all group-III atoms\n(cations) are treated as if they have an effective weighted-average mass. Here,\nwe showed that is critical to treat atomic masses explicitly, and that the\nthermal conductivity obtained with explicit atomic masses differs considerably\nfrom the value obtained with the average VCA cation mass. The larger the\ndifference between the cation masses, the poorer the VCA prediction for thermal\nconductivity. The random-alloy assumption in the VCA is also challenged,\nbecause X-ray diffraction and transmission electron microscopy show order in\nInGaAs, InAlAs, and GaAlAs epi-layers. We calculated thermal conductivity for\nthree common types of order [CuPt-B, CuAu-I, and triple-period-A (TPA)] and\nshowed that the experimental results for In$_{0.53}$Ga$_{0.47}$As and\nIn$_{0.52}$Al$_{0.48}$As, which are lattice matched to the InP substrate, can\nbe reproduced in molecular dynamics simulation with 2% and 8% of random\ndisorder, respectively. Based on our results, thermal transport in ternary\nIII-As alloys appears to be governed by the competition between mass-difference\nscattering, which is much more pronounced than the VCA suggests, and the\nlong-range order that these alloys support.",
        "positive": "Zig-zag ladders with staggered magnetic chirality in S = 3/2 compound\n  beta-CaCr2O4: The crystal and magnetic structures of the S = 3/2 chain antiferromagnet\nbeta-CaCr2O4 have been investigated by means of specific heat, magnetization,\nmuon relaxation and neutron powder diffraction between 300K and 1.5K. Owing to\nthe original topology of the Cr3+ magnetic lattice, which can be described as a\nnetwork of triangular ladders, equivalent to chains with nearest and\nnext-nearest neighbors interactions, evolution of the magnetic scattering\nintensity in this compound evidences two magnetic regimes : for 21K < T < 270K,\na low-dimensionality magnetic ordering of the Cr3+ spins is observed,\nsimultaneously with a strong contraction of the ladder legs, parallel to c.\nBelow TN = 21K, a complex antiferromagnetic ordering is evidenced, with an\nincommensurate propagation vector k = (0, 0, q) (q ~ 0.477 at 1.5K), as\nexchange interactions between ladders become significant. This complex magnetic\nordering can be described as a honeycomb-like arrangement of cycloids, running\nalong c, with staggered chiralities. The experimental observation of this\nstaggered chirality can be understood by taking into account antisymmetric\nDzyaloshinskii-Moriya exchange terms."
    },
    {
        "anchor": "Amorphous to Amorphous Insulator-Metal transition in GeSe$_3$:Ag glasses: We study an insulator-metal transition in a ternary chalcogenide glass\n(GeSe$_3$)$_{1-x}$Ag$_x$ for $x$=0.15 and 0.25. The conducting phase of the\nglass is obtained by using \"Gap Sculpting\" (Prasai et al, Sci. Rep. 5:15522\n(2015)) and it is observed that the metallic and insulating phases have nearly\nidentical DFT energies but have a conductivity contrast of ~10$^8$. The\ntransition from insulator to metal involves growth of an Ag-rich phase\naccompanied by a depletion of tetrahedrally bonded Ge(Se$_{1/2}$)$_4$ in the\nhost network. The relative fraction of the amorphous Ag$_2$Se phase and\nGeSe$_2$ phase is shown to be a critical determinant of DC conductivity.",
        "positive": "Anisotropic Landau level splitting and Lifshitz transition induced\n  magnetoresistance enhancement in ZrTe5 crystals: Magneto-transport study has been performed in ZrTe5 single crystals. The\nobserved Shubnikov-de Hass quantum oscillation at low temperature clearly\ndemonstrates the existence of a nontrivial band with small effective mass in\nZrTe5. Furthermore, we also revealed the 3D anisotropic nature of high-field\nLandau level splitting in ZrTe5, very different from the 2D behavior measured\nin previous transport studies. Besides these, an abnormal large enhancement of\nmagnetoresistance appears at high temperatures, which is believed to arise from\nthe Lifshitz transition induced two-carrier transport in ZrTe5. Our study\nprovides more understanding of the physical properties of ZrTe5 and sheds light\non potential application of ZrTe5 in spintronics."
    },
    {
        "anchor": "Chiral topological metals with multiple types of quasiparticle fermions\n  and large spin Hall effect in the SrGePt family materials: We present a prediction of chiral topological metals with several classes of\nunconventional quasiparticle fermions in a family of SrGePt-type materials in\nterms of first-principles calculations. In these materials, fourfold spin-3/2\nRarita-Schwinger-Weyl (RSW) fermion, sixfold excitation, and Weyl fermions\ncoexist around the Fermi level as spin-orbit coupling is considered, and the\nChern number for the first two kinds of fermions is the maximal value four. We\nfound that large Fermi arcs from spin-3/2 RSW fermion emerge on the\n(010)-surface, spanning the whole surface Brillouin zone. Moreover, there exist\nFermi arcs originating from Weyl points, which further overlap with trivial\nbulk bands. In addition, we revealed that the large spin Hall conductivity can\nbe obtained, which attributed to the remarkable spin Berry curvature around the\ndegenerate nodes and band-splitting induced by spin-orbit coupling. Our\nfindings indicate that the SrGePt family of compounds provide an excellent\nplatform for studying on topological electronic states and the intrinsic spin\nHall effect.",
        "positive": "Laser Liftoff of GaAs Thin Films: The high cost of single crystal III-V substrates limits the use of GaAs and\nrelated sphalerite III-V materials in many applications, especially\nphotovoltaics. Separating epitaxially-grown layers from a growth substrate can\nreduce costs, however the current approach, which uses an acid to laterally\netch an epitaxial sacrificial layer, is slow and can damage other device\nlayers. Here, we demonstrate a new approach that is orders of magnitude faster,\nand that enables more freedom in the selection of other device layers. We show\ndamage-free removal of an epitaxial single crystal GaAs film from its GaAs\ngrowth substrate using a laser that is absorbed by a smaller-band-gap,\npseudomorphic layer grown between the substrate and the GaAs film. The liftoff\nprocess transfers the GaAs film to a flexible polymer substrate, and the\ntransferred GaAs layer is indistinguishable in structural quality from its\ngrowth substrate."
    },
    {
        "anchor": "Light emission from gold nanoparticles under ultrafast near-infrared\n  excitation: thermal emission, inelastic light scattering or multiphoton\n  luminescence?: Gold nanoparticles emit broad-band upconverted luminescence upon irradiation\nwith pulsed infrared laser radiation. Although the phenomenon is widely\nobserved, considerable disagreement still exists concerning the underlying\nphysics - most notably over the applicability of concepts such as multiphoton\nabsorption, inelastic scattering, and interband and intraband electronic\ntransitions. Here, we study single particles and small clusters of particles by\nemploying a spectrally resolved power-law analysis of the irradiation-dependent\nemission as a sensitive probe of these physical models. Two regimes of emission\nare identified: at low irradiance levels of kW/cm2, the emission follows a\nwell-defined integer-exponent power law suggestive of a multiphoton process.\nHowever, at higher irradiance levels of several kW/cm2, the nonlinearity\nexponent itself depends on the photon energy detected, a tell-tale signature of\na radiating heated electron gas. We show that in this regime, the experiments\nare incompatible with both interband transitions and inelastic light scattering\nas the cause the luminescence, while they are compatible with the notion of\nluminescence linked to intraband transitions.",
        "positive": "Asymmetric modification of the magnetic proximity effect in Pt/Co/Pt\n  trilayers by the insertion of a Ta buffer layer: The magnetic proximity effect in top and bottom Pt layers induced by Co in\nTa/Pt/Co/Pt multilayers has been studied by interface sensitive, element\nspecific x-ray resonant magnetic reflectivity. The asymmetry ratio for\ncircularly polarized x-rays of left and right helicity has been measured at the\nPt $L_3$ absorption edge (11567 eV) with an in-plane magnetic field ($\\pm158$\nmT) to verify its magnetic origin. The proximity-induced magnetic moment in the\nbottom Pt layer decreases with the thickness of the Ta buffer layer. Grazing\nincidence x-ray diffraction has been carried out to show that the Ta buffer\nlayer induces the growth of Pt(011) rather than Pt(111) which in turn reduces\nthe induced moment. A detailed density functional theory study shows that an\nadjacent Co layer induces more magnetic moment in Pt(111) than in Pt(011). The\nmanipulation of the magnetism in Pt by the insertion of a Ta buffer layer\nprovides a new way of controlling the magnetic proximity effect which is of\nhuge importance in spin-transport experiments across similar kind of\ninterfaces."
    },
    {
        "anchor": "Boron phosphide under pressure: in situ study by Raman scattering and\n  X-ray diffraction: Cubic boron phosphide BP has been studied in situ by X-ray diffraction and\nRaman scattering up to 55 GPa at 300 K in a diamond anvil cell. The bulk\nmodulus of B0 = 174(2) GPa has been established, which is in excellent\nagreement with our ab initio calculations. The data on Raman shift as a\nfunction of pressure, combined with equation-of-state data, allowed us to\nestimate the Gr\\\"uneisen parameters of the TO and LO modes of zinc-blende\nstructure, {\\gamma}GTO = 1.16 and {\\gamma}GLO = 1.04, just like in the case of\nother AIIIBV diamond-like phases, for which {\\gamma}GTO > {\\gamma}GLO = 1. We\nalso established that the pressure dependence of the effective electro-optical\nconstant {\\alpha} is responsible for a strong change in relative intensities of\nthe TO and LO modes from ITO/ILO ~0.25 at 0.1 MPa to ITO/ILO ~2.5 at 45 GPa,\nfor which we also find excellent agreement between experiment and theory.",
        "positive": "Shear-transformation-zone theory of plastic deformation near the glass\n  transition: The shear-transformation-zone (STZ) theory of plastic deformation in\nglass-forming materials is reformulated in light of recent progress in\nunderstanding the roles played the effective disorder temperature and entropy\nflow in nonequilibrium situations. A distinction between fast and slow internal\nstate variables reduces the theory to just two coupled equations of motion, one\ndescribing the plastic response to applied stresses, and the other the dynamics\nof the effective temperature. The analysis leading to these equations contains,\nas a byproduct, a fundamental reinterpretation of the dynamic yield stress in\namorphous materials. In order to put all these concepts together in a realistic\ncontext, the paper concludes with a reexamination of the experimentally\nobserved rheological behavior of a bulk metallic glass. That reexamination\nserves as a test of the STZ dynamics, confirming that system parameters\nobtained from steady-state properties such as the viscosity can be used to\npredict transient behaviors."
    },
    {
        "anchor": "Particle Shape Control via Etching of Core-Shell Nanocrystals: The application of nanocrystals as heterogeneous catalysts and plasmonic\nnanoparticles requires fine control of their shape and chemical composition. A\npromising idea to achieve synergistic effects is to combine two distinct\nchemical and/or physical functionalities in bi-metallic core-shell\nnanocrystals. Although techniques for the synthesis of single-component\nnanocrystals with spherical or anisotropic shape are well established, new\nmethods are sought to tailor multicomponent nanocrystals. Here, we probe\netching in a controlled redox environment as a synthesis technique for\nmulti-component nanocrystals. Our Monte Carlo computer simulations demonstrate\nthe appearance of characteristic non-equilibrium intermediate microstructures\nthat are further thermodynamically tested and analyzed with molecular dynamics.\nConvex platelet, concave polyhedron, pod, cage and strutted-cage shapes are\nobtained at room temperature with fully coherent structure exposing\ncrystallographic facets and chemical elements along distinct particle\ncrystallographic directions. We observe that structural and dynamic properties\nare markedly modified compared to the untreated compact nanocrystal.",
        "positive": "Red Emission from Copper-Vacancy Color Centers in Zinc Sulfide Colloidal\n  Nanocrystals: Copper-doped zinc sulfide (ZnS:Cu) exhibits down-conversion luminescence in\nthe UV, visible, and IR regions of the electromagnetic spectrum; the visible\nred, green, and blue emission is referred to as R-Cu, G-Cu, and B-Cu,\nrespectively. The sub-bandgap emission arises from optical transitions between\nlocalized electronic states created by point defects, making ZnS:Cu a prolific\nphosphor material and an intriguing candidate material for quantum information\nscience, where point defects excel as single-photon sources and spin qubits.\nColloidal nanocrystals (NCs) of ZnS:Cu are particularly interesting as hosts\nfor the creation, isolation, and measurement of quantum defects, since their\nsize, composition, and surface chemistry can be precisely tailored for\nbio-sensing and opto-electronic applications. Here, we present a method for\nsynthesizing colloidal ZnS:Cu NCs that emit primarily R-Cu, which has been\nproposed to arise from the Cu$_{Zn}$-V$_S$ complex, an impurity-vacancy point\ndefect structure analogous to well-known quantum defects in other materials\nthat produce favorable optical and spin dynamics. First principles calculations\nconfirm the thermodynamic stability and electronic structure of\nCu$_{Zn}$-V$_S$. Temperature- and time-dependent optical properties of ZnS:Cu\nNCs show blueshifting luminescence and an anomalous plateau in the intensity\ndependence as temperature is increased from 19 K to 290 K, for which we propose\nan empirical dynamical model based on thermally-activated coupling between two\nmanifolds of states inside the ZnS bandgap. Understanding of R-Cu emission\ndynamics, combined with a controlled synthesis method for obtaining R-Cu\ncenters in colloidal NC hosts, will greatly facilitate the development of\nCu$_{Zn}$-V$_S$ and related complexes as quantum point defects in ZnS."
    },
    {
        "anchor": "The influence of ultrafast temporal energy regulation on the morphology\n  of Si surfaces through femtosecond double pulse laser irradiation: The effect of ultrashort laser-induced morphological changes upon irradiation\nof silicon with double pulse sequences is investigated under conditions that\nlead to mass removal. The temporal delay between twelve double and equal-energy\npulses (Ep=0.24J/cm2 each, with pulse duration tp=430fs, 800nm laser\nwavelength) was varied between 0 and 14ps and a decrease of the damaged area,\ncrater depth size and periodicity of the induced subwavelength ripples (by\n3-4%) was observed with increasing pulse delay. The proposed underlying\nmechanism is based on the combination of carrier excitation and energy\nthermalization and capillary wave solidification and aims to provide an\nalternative explanation to the control of ripple periodicity by temporal pulse\ntailoring. This work demonstrates the potential of pulse shaping technology to\nimprove nano/micro processing.",
        "positive": "Intermediate energy proton irradiation: rapid, high-fidelity materials\n  testing for fusion and fission energy systems: Fusion and advanced fission power plants require advanced nuclear materials\nto function under new, extreme environments. Understanding the evolution of\nmechanical and functional properties during radiation damage is essential to\nthe design and commercial deployment of these systems. The shortcomings of\nexisting methods could be addressed by a new technique - intermediate energy\nproton irradiation (IEPI) - using beams of 10 - 30 MeV protons to rapidly and\nuniformly damage bulk material specimens before direct testing of engineering\nproperties. IEPI is shown to achieve high fidelity to fusion and fission\nenvironments in both primary damage production and transmutation, often\nsuperior to nuclear reactor or typical (low-range) ion irradiation. Modeling\ndemonstrates that high doserates (0.1 - 1 DPA/per day) can be achieved in bulk\nmaterial specimens (100 - 300 {\\mu}m) with low temperature gradients and\ninduced radioactivity. The capabilities of IEPI are demonstrated through a 12\nMeV proton irradiation and tensile test of 250 {\\mu}m thick tensile specimens\nof a nickel alloy (Alloy 718), reproducing neutron-induced data. These results\ndemonstrate that IEPI enables high throughput assessment of materials under\nreactor-relevant conditions, positioning IEPI to accelerate the pace of\nengineering-scale radiation damage testing and allow for quicker and more\neffective design of nuclear energy systems."
    },
    {
        "anchor": "Plasmonically Enhanced Reflectance of Heat Radiation from Low-Bandgap\n  Semiconductor Microinclusions: Increased reflectance from the inclusion of highly scattering particles at\nlow volume fractions in an insulating dielectric offers a promising way to\nreduce radiative thermal losses at high temperatures. Here, we investigate\nplasmonic resonance driven enhanced scattering from microinclusions of\nlow-bandgap semiconductors (InP, Si, Ge, PbS, InAs and Te) in an insulating\ncomposite to tailor its infrared reflectance for minimizing thermal losses from\nradiative transfer. To this end, we compute the spectral properties of the\nmicrocomposites using Monte Carlo modeling and compare them with results from\nFresnel equations. The role of particle size-dependent Mie scattering and\nabsorption efficiencies, and, scattering anisotropy are studied to identify the\noptimal microinclusion size and material parameters for maximizing the\nreflectance of the thermal radiation. For composites with Si and Ge\nmicroinclusions we obtain reflectance efficiencies of 57 - 65% for the incident\nblackbody radiation from sources at temperatures in the range 400 - 1600\n{\\deg}C. Furthermore, we observe a broadbanding of the reflectance spectra from\nthe plasmonic resonances due to charge carriers generated from defect states\nwithin the semiconductor bandgap. Our results thus open up the possibility of\ndeveloping efficient high-temperature thermal insulators through use of the\nlow-bandgap semiconductor microinclusions in insulating dielectrics.",
        "positive": "Low-temperature ordering in a substitutional alloy with injecting\n  nonequilibrium vacancies: The FePt case: Achieving the compositionally ordered state in a substitutional alloy of two\nor more species can often be even critical for improving its functional\nproperties. To produce a highly ordered alloy, a longtime high-temperature (up\nto T=1000 K) treatment of the alloy is typically necessary because of\ninsufficient vacancy concentration (c_v) and their mobility. However, such\nprocessing affects the morphology and complicates the technology of functional\nalloys. We show theoretically that the ordering in the practically important\nFePt system (Fe_xPt_1-x with x being close to 0.5) is already achievable at\nT=450 K for reasonable times t<10^3 s due to frozen nonequilibrium vacancies.\nOur simulation is based on the Dienes equation for relaxation of the long-range\norder parameter (S), with taking additionally into account that the ordering\nkinetics in the alloy is mediated by vacancies. Importantly, the results of\nsuch simulation are in good agreement with previous experimental data on the\nordering kinetics. We also find that nanosecond laser pulses can be employed to\nachieve a sufficient level of c_v=10^-5 for effective low-temperature ordering."
    },
    {
        "anchor": "Order-disorder type critical behaviour at the magnetoelectric phase\n  transition in multiferroic DyMnO$_3$: We present the results of detailed dielectric investigations of the\nrelaxation dynamics in DyMnO$_3$ multiferroic manganite. Strong low-frequency\nrelaxation process near the paraelectric-ferroelectric phase transition is\nobserved. The high frequency mode is directly to the relaxational motion of\nmultiferroic domain walls. We provide an experimental evidence that this\nrelaxation mode corresponds to a chirality switching of the spin cycloid in\nDyMnO$_3$. We demonstrate that the relaxation dynamics in DyMnO$_3$ is typical\nfor an order-disorder phase transition and may be understood within a simple\nmodel with a double well potential. DyMnO$_3$ follows an order-disorder\ntransition scenario implicating that a short range cycloidal order of Mn-spins\nexists above $T_C$. These results suggest the interpretation of the\nparaelectric sinusoidal phase in manganites as a dynamical equilibrium of\nmagnetic cycloids with opposite chiralities.",
        "positive": "Comparison of first principles and semi-empirical models of the\n  structural and electronic properties of Ge$_{1-x}$Sn$_{x}$ alloys: We present and compare three distinct atomistic models -- based on first\nprinciples and semi-empirical approaches -- of the structural and electronic\nproperties of Ge$_{1-x}$Sn$_{x}$ alloys. Density functional theory calculations\nincorporating Heyd-Scuseria-Ernzerhof (HSE) and modified Becke-Johnson (mBJ)\nexchange-correlation functionals are used to perform structural relaxation and\nelectronic structure calculations for a series of Ge$_{1-x}$Sn$_{x}$ alloy\nsupercells. Based on HSE calculations, a semi-empirical valence force field\n(VFF) potential and $sp^{3}s^{\\ast}$ tight-binding (TB) Hamiltonian are\nparametrised. Comparing the HSE, mBJ and TB models, and using the HSE results\nas a benchmark, we demonstrate that: (i) mBJ calculations provide an accurate\nfirst principles description of the electronic structure at reduced\ncomputational cost, (ii) the VFF potential is sufficiently accurate to\ncircumvent the requirement to perform first principles structural relaxation,\nand (iii) TB calculations provide a good quantitative description of the alloy\nelectronic structure in the vicinity of the band edges. Our results also\nemphasise the importance of Sn-induced band mixing in determining the nature of\nthe conduction band structure of Ge$_{1-x}$Sn$_{x}$ alloys. The theoretical\nmodels and benchmark calculations we present inform and enable predictive,\ncomputationally efficient and scalable atomistic calculations for disordered\nalloys and nanostructures. This provides a suitable platform to underpin\nfurther theoretical investigations of the properties of this emerging\nsemiconductor alloy."
    },
    {
        "anchor": "The Doping effect of Chalcogen on the Two-Dimensional Ferromagnetic\n  Material Chromium Tribromide: Recently the discovery of magnetic order in two-dimensional monolayer\nchromium trihalides opens the new research field in two-dimensional materials.\nWe use first-principles calculations to systematically examine the doping\neffect of chalcogen on CrBr3. In the case of S-doping, four stable\nconfigurations, Cr2Br5S, Cr2Br4S2-A, Cr2Br4S2-B and Cr2Br3S3-A, are predicted\nto be ferromagnetic semiconductors. It is found that the new bands appearing in\nthe original bandgap are made up of S-p and Cr-d-egorbits, lead to the obvious\nreduce of bandgap and the enhanced optical absorption in the visible range. Due\nto the decrease of valence electron after chalcogen doping, the magnetic moment\nalso decreases with the increase of S atoms, and the character of ferromagnetic\nsemiconductor is always hold in a wide range of strain. The results shown that\nmonolayer CrBr3with chalcogen doping supply a effectual way to control the\nmagnetism and extend the optoelectronic applications.",
        "positive": "Advanced interfacial phase change material: structurally confined and\n  interfacially extended superlattice: Interfacial Phase Change Memory (iPCM) retrench unnecessary power consumption\ndue to wasted heat generated during phase change by reducing unnecessary\nentropic loss. In this study, an advanced iPCM (GeTe/Ti-Sb2Te3 Superlattice) is\nsynthesized by doping Ti into Sb2Te3. Structural analysis and density\nfunctional theory (DFT) calculations confirm that bonding distortion and\nstructurally well-confined layers contribute to improve phase change properties\nin iPCM. Ti-Sb2Te3 acts as an effective thermal barrier to localize the\ngenerated heat inside active region, which leads to reduction of switching\nenergy. Since Ge-Te bonds adjacent to short and strong Ti-Te bonds are more\nelongated than the bonds near Sb-Te, it is easier for Ge atoms to break the\nbond with Te due to strengthened Peierls distortions (Rlong/Rshort) during\nphase change process. Properties of advanced iPCM (cycling endurance, write\nspeed/energy) exceed previous records. Moreover, well-confined multi-level\nstates are obtained with advanced iPCM, showing potential as a neuromorphic\nmemory. Our work paves the way for designing superlattice based PCM by\ncontrolling confinement layers."
    },
    {
        "anchor": "Landau model for the phase diagrams of the orthorhombic rare-earth\n  manganites RMnO3: The present work aims to describe, within a single phenomenological approach,\nthe specific sequence of phase transitions observed in the rare-earth\nmanganites RMnO3 at zero magnetic field. It is shown that a single integrated\ndescription of the temperature versus composition phase diagrams of these\ncompounds and related solid solutions can be obtained within the scope of\nLandau theory by adopting the so called type-II description of the modulated\nphases.",
        "positive": "Flexible transistors exploiting P3HT on paper substrates and graphene\n  oxide films as gate dielectrics: proof of concept: In this paper we report: the use of GO in aqueous solution as a gate\ndielectric material, its application to a MOS transistor based on organic\nsemiconductor and the use of paper as substrate material."
    },
    {
        "anchor": "Spin Helix of Magnetic Impurities in Two-dimensional Helical Metal: We analyze the Ruderman-Kettel-Kasuya-Yosida(RKKY) interaction between\nmagnetic impurities embedded in the helical metal on the surface of\nthree-dimensional topological insulators. Apart from the conventional RKKY\nterms, the spin-momentum locking of conduction electrons also leads to a\nsignificant Dzyaloshinskii-Moriya (DM) interaction between impurity spins. For\na chain of magnetic impurities, the DM term can result in single-handed spin\nhelix on the surface. The handedness of spin helix is locked with the sign of\nFermi velocity of the emergent Dirac fermions on the surface. We also show the\npolarization of impurity spins can be controlled via electric voltage for\ndilute magnetic impurity concentration.",
        "positive": "Direct Hydrogen Production from Water/Seawater by\n  Irradiation/Vibration-Activated Using Defective Ferroelectric BaTiO3-x\n  Nanoparticles: Hydrogen is a promising fossil-fuel alternative fuel owing to its\nenvironmentally neutral emissions and high energy density. However, the need\nfor purified water and external power are critical hindrances to implementation\nof hydrogen production. The present work reveals the potential to overcome\nthese shortcomings through piezo-photocatalysis of seawater using BaTiO3-x\n(BTO) nanoparticles. This material was made piezoelectrically active by\nannealing under different atmospheres, including O2, N2, Ar, and H2, the latter\nof which caused Ti4+ to Ti(4-x)+ multiple reductions and structural expansions\nthat stabilized piezoelectric tetragonal BTO domains. The resultant defect\nequilibria combine ionic and electron effects, including Ti redox reactions,\ncharge-compensating surface oxygen vacancy formation, and color centre\nalterations. Further, variety of experimental techniques revealed the effects\nof reduction on the energy band structure. A strong piezoelectric effect and\nthe presence of self-polarization were confirmed by piezoresponse force\nmicroscopy, while simulation work clarified the role of vibration on band\nbending deriving from the former. The performance data contrasted H2 evolution\nusing deionized (DI) water, simulated seawater, and natural seawater subjected\nto photocatalysis, piezocatalysis, and piezo-photocatalysis. An efficient H2\nevolution rate of 132.4 micromol/g/h was achieved from DI water using\npiezo-photocatalysis for 5 h. In contrast, piezocatalysis for 2 h followed by\npiezo-photocatalysis for 3 h resulted in H2 evolution rates of 100.7\nmicromol/g/h for DI water, 63.4 micromol/g/h for simulated seawater, and 48.7\nmicromol/g/h for natural seawater. This work provides potential new strategies\nfor large-scale green H2 production using abundant natural resources with\nconventional piezoelectric material while leveraging the effects of ions\ndissolved in seawater."
    },
    {
        "anchor": "Exploring the Structural Stability, Electronic and Thermal Attributes of\n  synthetic 2D Materials and their Heterostructures: Based on first-principles calculations, we have investigated the structural\nstability, electronic structures, and thermal properties of the monolayer\nXSi2N4 (X= Ti, Mo, W) and their lateral (LH) and vertical heterostructures\n(VH). We find that these heterostructures are energetically and dynamically\nstable due to high cohesive and binding energies, and no negative frequencies\nin the phonon spectra. The XSi2N4 (X= Ti, Mo, W) monolayers, the\nTiSi2N4/MoSi2N4-LH, MoSi2N4/WSi2N4-LH, and MoSi2N4/WSi2N4-VH possess a\nsemiconducting nature with an indirect band gap ranging from 0.30 to 2.60 eV.\nAt room temperature, the Cv values are found to be between 100 and 416 J/K.mol\nfor the monolayers and their heterostructures, suggesting the better ability to\nretain heat with respect to transition metal dichalcogenides. Our study unveils\nthe excellent attributes of XSi2N4 2D monolayers and their heterostructures,\nproposing them as potential candidates in nanoelectronics and thermoelectric\napplications.",
        "positive": "Thermal response of double-layered metal films after ultrashort pulsed\n  laser irradiation: the role of nonthermal electron dynamics: The thermal response of a Cu-Ti double-layered film is investigated after\nlaser irradiation with ultrashort pulses (pulse duration {\\tau}p=50fs, 800nm\nlaser wavelength) in submelting conditions by including the influence of\nnonthermal electrons. A revised two-temperature model is employed to account\nfor the contribution of nonthermal electron distribution while the variation of\nthe optical properties of the material during the laser beam irradiation is\nalso incorporated into the model. Theoretical results can provide significant\ninsight into the physical mechanism that characterize electron dynamics and can\nfacilitate production of controllable ultra-high strength Cu-Ti alloys with\npromising applications."
    },
    {
        "anchor": "Fr\u00f6hlich electron-phonon vertex from first principles: We develop a method for calculating the electron-phonon vertex in polar\nsemiconductors and insulators from first principles. The present formalism\ngeneralizes the Fr\\\"ohlich vertex to the case of anisotropic materials and\nmultiple phonon branches, and can be used either as a post-processing\ncorrection to standard electron-phonon calculations, or in conjunction with\n{\\it ab initio} interpolation based on maximally localized Wannier functions.\nWe demonstrate this formalism by investigating the electron-phonon interactions\nin anatase TiO$_2$, and show that the polar vertex significantly reduces the\nelectron lifetimes and enhances the anisotropy of the coupling. The present\nwork enables {\\it ab initio} calculations of carrier mobilities, lifetimes,\nmass enhancement, and pairing in polar materials.",
        "positive": "Interlayer coupling in EuS/SrS, EuS/PbSe and EuS/PbTe magnetic\n  semiconductor superlatices: Neutron reflectivity studies of EuS/SrS, EuS/PbSe, and EuS/PbTe\nall-semiconductor superlattices were carried out in search for exchange\ninterlayer coupling. A relatively weak antiferromagnetic coupling was found in\nEuS/SrS and in EuS/PbSe systems but no interlayer coupling was detected in\nEuS/PbTe superlattices. In EuS/SrS, where the SrS spacer is an insulator\n($E_g\\approx 4$ eV), a very weak and short range interlayer coupling is in\nagreement with the earlier theoretical predictions that the interlayer coupling\nstrength in EuS-based magnetic semiconductor superlattices depends strongly on\nthe energy gap of the nonmagnetic layer and should decrease with an increase of\nthe energy gap of the spacer material. A weak coupling in EuS/PbSe and no\ncoupling in EuS/PbTe, where both PbSe and PbTe are narrow-gap semiconductors\n($E_g\\approx 0.3$ eV), is in disagreement not only with the theoretical\nexpectations but also in a stark contrast with earlier results for another\nnarrow-gap spacer system -- EuS/PbS, where pronounced antiferromagnetic\ncoupling persists even in samples with PbS layer thickness as large as 200 \\AA.\nA possible influence of the increasing lattice mismatch between EuS and the\nspacer materials (0.5%, 0.8%, 2.5%, and 8.2% for PbS, SrS, PbSe, and PbTe,\nrespectively) on the magnetic in-plane ordering of EuS layer and, consequently,\non the interlayer coupling was investigated by polarized neutron reflectometry\nin the case of EuS/PbTe."
    },
    {
        "anchor": "A Unified View of Topological Phase Transition in Band Theory: We develop a unified view of topological phase transitions (TPTs) in solids\nby revising the classical band theory with the inclusion of topology.\nRe-evaluating the band evolution from an \"atomic crystal\" [a normal insulator\n(NI)] to a solid crystal, such as a semiconductor, we demonstrate that there\nexists ubiquitously an intermediate phase of topological insulator (TI), whose\ncritical transition point displays a linear scaling between electron hopping\npotential and average bond length, underlined by deformation-potential theory.\nThe validity of the scaling relation is verified in various two-dimensional\n(2D) lattices regardless of lattice symmetry, periodicity, and form of electron\nhoppings, based on a generic tight-binding model. Significantly, this linear\nscaling is shown to set an upper bound for the degree of structural disorder to\ndestroy the topological order in a crystalline solid, as exemplified by\nformation of vacancies and thermal disorder. Our work formulates a simple\nframework for understanding the physical nature of TPTs with significant\nimplications in practical applications of topological materials.",
        "positive": "Stochastic density functional theory combined with Langevin dynamics for\n  warm dense matter: This study overviews and extends a recently developed stochastic\nfinite-temperature Kohn-Sham density functional theory to study warm dense\nmatter using Langevin dynamics, specifically under periodic boundary\nconditions. The method's algorithmic complexity exhibits nearly linear scaling\nwith system size and is inversely proportional to the temperature.\nAdditionally, a novel linear-scaling stochastic approach is introduced to\nassess the Kubo-Greenwood conductivity, demonstrating exceptional stability for\nDC conductivity. Utilizing the developed tools, we investigate the equation of\nstate, radial distribution, and electronic conductivity of Hydrogen at a\ntemperature of 30,000K. As for the radial distribution functions, we reveal a\ntransition of Hydrogen from gas-like to liquid-like behavior as its density\nexceeds $4 g/cm^3$. As for the electronic conductivity as a function of the\ndensity, we identified a remarkable isosbestic point at frequencies around 7eV,\nwhich may be an additional signature of a gas-liquid transition in Hydrogen at\n30,000K."
    },
    {
        "anchor": "H induced decohesion of an Al grain boundary investigated with first\n  principles: Proposed general conditions for instant breakage and delayed\n  fracture: The uniaxial tensile test response of a H decorated $\\Sigma$ 5 [100] twist\ngrain boundary (GB) in face-centered-cubic Al has been examined with first\nprinciples. The impurity shows a strong tendency to relocate during loading. To\ncapture these H movements, the standard model framework was extended to probe\nloading-unloading hysteresis. If the maximum tensile stress accepted by the H\ndecorated GB in the slow fracture limit is reached before the maximum\nacceptable strain, exceeding this stress may trigger a H influx-controlled\ndestabilization, as opposed to 'immediate' breakage. Such 'delayed' failure\nappears likely whenever the H attraction to a GB displays a monotonic decrease\nwith increased loading.",
        "positive": "Weyl Fermions in antiferromagnetic Mn(3)Sn and Mn(3)Ge: The anomalous Hall effect in the noncollinear antiferromagnetic metals\nMn(3)Ge and Mn(3)Sn has been observed after a theoretical prediction made by us\n(EPL, 108, 67001 (2014)). The experimental values of the anomalous Hall\nconductivities (AHC) are large as are the theoretical values. Recently measured\nthermoelectric properties mirror the large AHC and clearly show that the\ntransport is by quasiparticles at the Fermi energy. We here make an attempt to\nunravel the origin of the large AHC and propose that both Mn(3)Sn and Mn(3)Ge\nhost Weyl points, which were recently discovered in semimetals. For this\npurpose we determine the electronic structure ab initio in the local\nspin-density functional approximation. The Weyl points are found to occur below\nthe Fermi energy and we argue that spots of large Berry flux ('hot spot') that\nare seen at the Fermi surface are produced by the Weyl nodes."
    },
    {
        "anchor": "Non-metric connection and metric anomalies in materially uniform elastic\n  solids: Metric anomalies arising from a distribution of point defects (intrinsic\ninterstitials, vacancies, point stacking faults), thermal deformation,\nbiological growth, etc. are well known sources of material inhomogeneity and\ninternal stress. By emphasizing the geometric nature of such anomalies we seek\ntheir representations for materially uniform crystalline elastic solids. In\nparticular, we introduce a quasi-plastic deformation framework where the\nmultiplicative decomposition of the total deformation gradient into an elastic\nand a plastic deformation is established such that the plastic deformation is\nfurther decomposed multiplicatively in terms of a deformation due to\ndislocations and another due to metric anomalies. We discuss our work in the\ncontext of quasi-plastic strain formulation and Weyl geometry. We also derive a\ngeneral form of metric anomalies which yield a zero stress field in the absence\nof other inhomogeneities and any external sources of stress.",
        "positive": "In_xGa_{1-x}Sb MOSFET: Performance Analysis by Self Consistent CV\n  Characterization and Direct Tunneling Gate Leakage Current: In this paper, Capacitance-Voltage (C-V) characteristics and direct tunneling\n(DT) gate leakage current of antimonide based surface channel MOSFET were\ninvestigated. Self-consistent method was applied by solving coupled\nSchr\\\"odinger-Poisson equation taking wave function penetration and strain\neffects into account. Experimental I-V and gate leakage characteristic for\np-channel InxGa1-xSb MOSFETs are available in recent literature. However, a\nself- consistent simulation of C-V characterization and direct tunneling gate\nleakage current is yet to be done for both n- channel and p-channel InxGa1-xSb\nsurface channel MOSFETs. We studied the variation of C-V characteristics and\ngate leakage current with some important process parameters like oxide\nthickness, channel composition, channel thickness and temperature for n-channel\nMOSFET in this work. Device performance should improve as compressive strain\nincreases in channel. Our simulation results validate this phenomenon as\nballistic current increases and gate leakage current decreases with the\nincrease in compressive strain. We also compared the device performance by\nreplacing InxGa1-xSb with InxGa1-xAs in channel of the structure. Simulation\nresults show that performance is much better with this replacement."
    },
    {
        "anchor": "First-Principles Computations for KTN: Solid solutions of KTaO$_{3}$ and KNbO$_{3}$ (KTN) exhibit unusual dielectric\nproperties at ferroelectric phase transitions, which are usually associated\nwith a Nb instability that is often explained by the large Nb dynamical charge\nin oxides. Using non-self-consistent VASP computations, we showed earlier that\nthe Nb dynamical charge in layerd KTN strongly depends on the local environment\nof Nb. In the present study, we have performed self-consistent first-principles\ncomputations for fixed composition KTa7/8Nb1/8O3 in different configurations\nshown. We computed the equilibrium ionic positions, Born charges, force\nconstants, vibration frequencies and modes. We also discuss the question\nwhether Nb has a multi-well potential, and the field dependence of\nsusceptibility.",
        "positive": "Transition between half-metal and ferromagnetic semiconductor induced by\n  silicon vacancy in epitaxial silicene: Since the inevitability in experimental synthesis, defects show great\nimportance to many materials. They will deeply regulate the properties of the\nmaterials, and then affect the further applications. Thus, exploring the\neffects of defects on the properties of materials is desired. Here, by using\nfirst-principles calculations, we systematically studied the effect of silicon\nvacancy defects on the properties of silicene generated on Nterminated cubic\nboron nitride (111) surface. It is found that the introduction of silicon\nvacancy would trigger transition between half-metal and ferromagnetic\nsemiconductor. With small vacancy ratios of 1/36 and 1/24, the ground-state of\nthe samples would behave as ferromagnetic semiconductors, and the band gaps are\nabout 1.25 and 0.95 eV, respectively. When the vacancy ratio is increased up to\n1/6, the sample would turn into a ferromagnetic half-metal with a half-metallic\ngap of around 0.15 eV. The change of the electronic structure of the samples is\ndriven by the different electron transfer between silicon layer and substrate,\ni.e., there will be different amount of electrons transferred from the silicon\nlayer to the substrate when the vacancy ratio is altered. This work would open\na new way to regulate the properties of materials and extend applications in\nnanoelectronic field."
    },
    {
        "anchor": "High-pressure stability and compressibility of APO4 (A = La, Nd, Eu, Gd,\n  Er, and Y) orthoposphates: A synchrotron powder x-ray diffraction study: Room temperature angle-dispersive x-ray diffraction measurements on\nzircon-type YPO4 and ErPO4, and monazite-type GdPO4, EuPO4, NdPO4, and LaPO4\nwere performed in a diamond-anvil cell up to 27 GPa using neon as\npressure-transmitting medium. In the zircon-structured oxides we found evidence\nof a reversible pressure-induced structural phase transformation from zircon to\na monazite-type structure. The onset of the transition is near 17-20 GPa. In\nLaPO4 a non-reversible transition is found around 26 GPa, being a barite-type\nstructure proposed for the high-pressure phase. In the other three monazites,\nthis structure is found to be stable up to highest pressure reached in the\nexperiments. No additional phase transitions or evidences of chemical\ndecomposition are found in the experiments. The equations of state and axial\ncompressibility for the different phases are also determined. In particular, we\nfound that in a given compound the monazite structure is less compressible than\nzircon structure, being this fact related to the larger packing efficiency of\nmonazite compared with zircon. The differential bond compressibility of\ndifferent polyhedra is also reported and related the anisotropic\ncompressibility of both structures. Finally, the sequence of structural\ntransitions and compressibilities are discussed in comparison with other\norhtophosphates.",
        "positive": "Thermal diffusivity and its lower bound in orthorhombic SnSe: The orthorhombic monochalcogenide SnSe has attracted much attention in recent\nyears as a promising high-temperature thermoelectric material. We present a\nstudy of its thermal conductivity and specific heat of SnSe between 2~K and\n300~K and quantify its anisotropic thermal diffusivity, $D$. For both\ncrystallographic orientations, thermal diffusivity remains above the recently\nidentified Planckian limit ($D > v_s^2 \\tau_P$, where $v_s$ is the sound\nvelocity and $\\tau_P= \\hbar/k_BT$) and its anisotropy in $D$ is set by the\nanisotropy of $v_s$. Comparison with cubic members of the IV-VI family leads to\na consistent picture, where the diffusivity in all members of the family is set\nby the product of v$_s$, $\\tau_P$ and the 'melting' velocity derived from the\nmelting temperature."
    },
    {
        "anchor": "Spontaneous atomic ordering and magnetism in epitaxially stabilized\n  double perovskites: We have studied the atomic ordering of B-site transition metals and magnetic\nproperties in the pulsed-laser deposited films of La2CrFeO6 (LCFO) and La2VMnO6\n(LVMO), whose bulk materials are known to be single perovskites with random\ndistribution of the B-site cations. Despite similar ionic characters of\nconstituent transition metals in each compound, the maximum B-site order\nattained was surprisingly high, ~90% for LCFO and ~80% for LVMO, suggesting a\nsignificant role of epitaxial stabilization in the spontaneous ordering\nprocess. Magnetization and valence state characterizations revealed that the\nmagnetic ground state of both compounds was coincidently ferrimagnetic with\nsaturation magnetization of ~2myuB per formula unit, unlike those predicted\ntheoretically. In addition, they were found to be insulating with optical band\ngaps of 1.6 eV and 0.9 eV for LCFO and LVMO, respectively. Our results present\na wide opportunity to explore novel magnetic properties of binary\ntransition-metal perovskites upon epitaxial stabilization of the ordered phase.",
        "positive": "First-principles study of structurally modulated multiferroic\n  CaMn$_7$O$_{12}$: We study the electronic and magnetic structures of multiferroic\nCaMn$_7$O$_{12}$ by first-principle calculations, based on the experimentally\ndetermined modulated crystal structure. We confirm the presence of a 3$d$\norbital modulation of the Mn2 (Mn$^{3+}$) sites, previously inferred from the\nJahn-Teller crystal distortions. Our results indicate that in the multiferroic\nphase the magnetic structure of the Mn3 (Mn$^{4+}$) sites is anharmonically\nmodulated via orbitally-mediated coupling with the structural modulation, and\nthat the Dzyaloshinskii-Moriya and exchange striction mechanisms contribute\nequally to the polarization"
    },
    {
        "anchor": "Origin of Hole-Trapping States in Solution-Processed Copper(I)\n  Thiocyanate (CuSCN) and Defect-Healing by I$_2$ Doping: Solution-processed copper(I) thiocyanate (CuSCN) typically exhibits low\ncrystallinity with short-range order; the defects result in a high density of\ntrap states that limit the device performance. Despite the extensive electronic\napplications of CuSCN, its defect properties have not been studied in detail.\nThrough X-ray absorption spectroscopy, pristine CuSCN prepared from the\nstandard diethyl sulfide-based recipe is found to contain under-coordinated Cu\natoms, pointing to the presence of SCN vacancies. A defect passivation strategy\nis introduced by adding solid I$_2$ to the processing solution. At small\nconcentrations, the iodine is found to exist as I$^-$ which can substitute for\nthe missing SCN$^-$ ligand, effectively healing the defective sites and\nrestoring the coordination around Cu. Applying I$_2$-doped CuSCN as a p-channel\nin thin-film transistors shows that the hole mobility increases by more than\nfive times at the optimal doping concentration of 0.5 mol%. Importantly, the\non/off current ratio and the subthreshold characteristics also improve as the\nI$_2$ doping method leads to the defect healing effect while avoiding the\ncreation of detrimental impurity states. An analysis of the capacitance-voltage\ncharacteristics corroborates that the trap state density is reduced upon I$_2$\naddition. The contact resistance and bias-stress stability of the devices also\nimprove. This work shows a simple and effective route to improve hole transport\nproperties of CuSCN which is applicable to wide-ranging electronic and\noptoelectronic applications.",
        "positive": "Controlling polarization of spintronic THz emitter by remanent\n  magnetization texture: Terahertz (THz) sciences and technologies have contributed to a rapid\ndevelopment of a wide range of applications and expanded the frontiers in\nfundamental science. Spintronic terahertz emitters offer conceptual advantages\nsince the spin orientation in the magnetic layer can be easily controlled\neither by the externally applied magnetic field or by the internal magnetic\nfield distribution determined by the specific shape of the magnetic elements.\nHere, we report a switchable terahertz source based on micropatterned magnetic\nheterostructures driven by femtosecond laser pulses. We show that the precise\ntunability of the polarization state is facilitated by the underlying\nmagnetization texture of the magnetic layer that is dictated by the shape of\nthe microstructure. These results also reveal the underlying physical\nmechanisms of a nonuniform magnetization state on the generation of ultrafast\nspin currents in the magnetic heterostructures. Our findings indicate that the\nemission of the linearly polarized THz waves can be switched on and off by\nsaturating the sample using a biasing magnetic field, opening fascinating\nperspectives for integrated on-chip THz devices with wide-ranging potential\napplications."
    },
    {
        "anchor": "First Principles Study of Adsorption, Diffusion and Dissociation of NH_3\n  on Ni and Pd Surfaces: Using the plane wave pseudopotential method within the density functional\ntheory with the generalized gradient approximation for exchange and correlation\npotential, we have calculated adsorption energies (Ead), diffusion barriers and\nthe first dissociation barriers (E1) for NH3 on the Ni(111), Pd(111) and\nNi(211) surfaces. The top sites are found to be preferred for NH3 adsorption on\nNi(111) and Pd(111). The diffusion barrier is calculated to be substantially\nhigher for Pd(111) than for Ni(111). We also find that during the first\ndissociation step (NH3 => NH2 +H) on Ni(111) surface NH2 moves from the top\nsite to the nearest hollow site, while on Ni(211) it moves from the initial top\nsite at the step edge to the bridge site in the same step chain. H is found to\noccupy the hollow sites for both surfaces. For the reaction on Ni(111), the Ead\nis found to be 0.23 eV lower than E1, while at the step of Ni(211), E1 and Ead\nare almost equal to each other. This suggests that the molecule will rather\ndesorb on Ni(111) than dissociate, whereas at the step the dissociation is\nfavorable.",
        "positive": "Suppression of long range magnetic ordering and electrical conduction in\n  Y$_{1.7}$Bi$_{0.3}$Ir$_2$O$_7$ thin film: We find that the long-range magnetic ordering is absent and electrical\nconduction suppressed in Y$_{1.7}$Bi$_{0.3}$Ir$_2$O$_7$/YSZ(100) thin film\nprepared by pulsed laser deposition. The sharp down-turn of inverse magnetic\nsusceptibility X-1(T) from the conventional Curie-Weiss behaviour below T* ~\n168K suggests an inhomogeneous ferromagnetic Griffiths like phase. The\ntransport and magnetic properties are explained on the basis of the coexistence\nof mixed oxidation states of Ir, (i.e. Ir4+ and Ir3+) leading to non-magnetic\ndefects and reduction in t2g density of states at the Fermi level."
    },
    {
        "anchor": "Investigating the \"Cocoon Effect\" in Niobium-Copper Alloy: Metallic\n  Nano-Precipitate Distribution and Niobium Migration: We report the observation of the metallic niobium migration within the molten\nCu-Nb alloy mass on the synthesis of nano-granular Cuxwt%Nb evolution, we\nprepared a series of granular samples by rapidly cooling a molten mixture of\nCuxwt$%$Nb, where the niobium concentration varied (x=3,5,15,20). Our main goal\nin this work was not only to establish a systematic, innovative and robust\nmethod to obtaining good quality samples, but also provide a clear recipe for\nobtaining similar systems to the investigations of their interesting physical\nproperties. Beyond the understanding of the \"Cocoon Effect\" in Niobium-Copper\nalloys, we include a wide complementary elsewhere investigation into the very\ninteresting and rich superconducting properties exhibited by the Niobium-Copper\nalloy. By employing a robust synthesis method, we successfully obtained samples\ncharacterized by well-defined spherical nano-precipitates of niobium, featuring\nregular sizes and grain spacing. Our study contributes not only to our\nunderstanding of the Niobium-Copper molten phase separation, micro-structure\nand the Cocoon Effect in these metallic alloys, but also sheds light on the\nintricate and important implications for the development and optimization of\ngood quality granular metallic alloys for various applications. From our work,\nwe obtained very impressive micro structural results, such as: $d_{m}$ = 1.2\n$\\mu$m, $D_{m}$ $\\le$ 2.2 $\\mu$m and $\\rho$ =1.785 $\\mu$$m^{2}$, where $d_{m}$\nis the distance between Niobium grains, $D_{m}$ is the mean diameter of Niobium\ngrains and $\\rho$ is the Niobium grain mean density in the Copper matrix.",
        "positive": "Variable resistor made by repeated steps of epitaxial deposition and\n  lithographic structuring of oxide layers by using wet chemical etchants: Variable resistors were constructed from epitaxial SrRuO3 (SRO),\nLa0.67Sr0.33MnO3 (LSMO) and SrTiO3 layers with perovskite crystal structure.\nEach layer was patterned separately by lithographic methods. Optimized wet\nchemical etchants and several polishing steps in organic solvents allowed good\nepitaxy of subsequent layers, comparable to epitaxy on pristine substrates.\nPeriodate as the oxidizing agent for SRO and iodide with ascorbic acid as the\nreducing agents for LSMO were used to attack these chemically resistant oxides.\nThe final devices changed their conductance in a similar manner to previously\ndescribed variable resistors that were defined with shadow masks."
    },
    {
        "anchor": "The effect of ion irradiation on dephasing of coherent optical phonons\n  in GaP: The dephasing of coherent longitudinal optical (LO) phonons in ion-irradiated\nGaP has been investigated with a femtosecond pump-probe technique based on\nelectro-optic sampling. The dephasing time of the coherent LO phonon is found\nto be dramatically prolonged by the introduction of a small amount of defects\nby means of Ga-ion irradiation. The maximum dephasing time observed at room\ntemperature is 9.1 ps at a Ga$^{+}$ ion dose of 10$^{13}$/cm$^{2}$, which is\nsignificantly longer than the value of 8.3 ps for GaP before ion irradiation.\nThe longer dephasing time is explained in terms of the suppression of\nelectron-LO-phonon scattering by the presence of defect-induced deep levels.",
        "positive": "Accurate effective harmonic potential treatment of the high-temperature\n  cubic phase of Hafnia: HfO$_2$ is an important high-$\\kappa$ dielectric and ferroelectric,\nexhibiting a complex potential energy landscape with several phases close in\nenergy. It is, however, a strongly anharmonic solid, and thus describing its\ntemperature-dependent behavior is methodologically challenging. We propose an\napproach based on self-consistent, effective harmonic potentials and\nhigher-order corrections to study the potential energy surface of anharmonic\nmaterials. The introduction of a reweighting procedure enables the usage of\nunregularized regression methods and efficiently harnesses the information\ncontained in every data point obtained from density functional theory. This\nrenders the approach highly efficient and a promising candidate for large-scale\nstudies of materials and phase transitions. We detail the approach and test it\non the example of the high-temperature cubic phase of HfO$_2$. Our results for\nthe thermal expansion coefficient, $\\alpha_V \\approx 3.3\\times 10^{-5}$\nK$^{-1}$, are in agreement with existing experimental ($\\alpha_V \\approx\n4\\pm1\\times 10^{-5}$ K$^{-1}$) and theoretical ($\\alpha_V \\approx 5\\pm1\\times\n10^{-5}$ K$^{-1}$) work. Likewise, the bulk modulus agrees well with\nexperiment. We show the detailed temperature dependence of these quantities."
    },
    {
        "anchor": "Engineering the electronic, magnetic and gap-related properties of the\n  quinternary half-metallic Heusler alloys: We review the electronic and magnetic properties of the quinternary full\nHeusler alloys of the type Co$_2$[Cr$_{1-x}$Mn$_x$][Al$_{1-y}$Si$_y$] employing\nthree different approaches : (i) the coherent potential approximation (CPA),\n(ii) the virtual crystal approximation (VCA), and (iii) supercell calculations\n(SC). All three methods give similar results and the local environment\nmanifested itself only for small details of the density of states. All alloys\nunder study are shown to be half-metals and their total spin moments follow the\nso-called Slater-Pauling behavior of the ideal half-metallic systems. We\nespecially concentrate on the properties related to the minority-spin band-gap.\nWe present the possibility to engineer the properties of these alloys by\nchanging the relative concentrations of the low-valent transition metal and\n$sp$ atoms in a continuous way. Our results show that for realistic\napplications, ideal are the compounds rich in Si and Cr since they combine\nlarge energy gaps (around 0.6 eV), robust half-metallicity with respect to\ndefects (the Fermi level is located near the middle of the gap) and high values\nof the majority-spin density of states around the Fermi level which are needed\nfor large values of the perfectly spin-polarized current in spintronic devices\nlike spin-valves or magnetic tunnel junctions.",
        "positive": "Comparison of GaN nanowires grown on c-, r- and m-plane sapphire\n  substrates: Gallium nitride nanowires were grown on c-plane, r-plane and m-plane sapphire\nsubstrates in a showerhead metalorganic chemical vapor deposition system using\nnickel catalyst with trimethylgallium and ammonia as precursors. We studied the\ninfluence of carrier gas, growth temperature, reactor pressure, reactant flow\nrates and substrate orientation in order to obtain thin nanowires. The\nnanowires grew along the <10-11> and <10-10> axes depending on the substrate\norientation. These nanowires were further characterized using x-ray\ndiffraction, electron microscopy, photoluminescence and Raman spectroscopy."
    },
    {
        "anchor": "Hybrid Functional Study Rationalizes the Simple Cubic Phase of Calcium\n  at High Pressures: Simple cubic (SC) phase has been long experimentally determined as the\nhigh-pressure phase III of elemental calcium (Ca) since 1984. However, recent\ndensity functional calculations within semi-local approximation showed that\nthis SC phase is structurally unstable by exhibiting severely imaginary\nphonons, and is energetically unstable with respect to a theoretical\nbody-centered tetragonal I41/amd structure over the pressure range of phase\nIII. These calculations generated extensive debates on the validity of SC\nphase. Here we have re-examined the SC structure by performing more precise\ndensity functional calculations within hybrid functionals of\nHeyd-Scuseria-Erhzerhof (HSE) and PBE0. Our calculations were able to\nrationalize fundamentally the phase stability of SC structure over all other\nknown phases by evidence of its actual energetic stability above 33 GPa and its\nintrinsically dynamical stability without showing any imaginary phonons in the\nentire pressure range studied. We further established that the long-thought\ntheoretical I41/amd structure remains stable in a narrow pressure range before\nentering SC phase and is actually the structure of experimental Ca-III'\nsynthesized recently at low temperature 14 K as supported by the excellent\nagreement between our simulated X-ray diffraction patterns and the experimental\ndata. Our results shed strong light on the crucial role played by the precise\nelectron exchange energy in a proper description of the potential energy of Ca.",
        "positive": "The Behavior of Flexible MIL-53(Al) upon CH4 and CO2 Adsorption: The use of the osmotic thermodynamic model, combined with a series of methane\nand carbon dioxide gas adsorption experiments at various temperatures, has\nallowed shedding some new light on the fascinating phase behavior of flexible\nMIL-53(Al) metal-organic frameworks. A generic temperature-loading phase\ndiagram has been derived; it is shown that the breathing effect in MIL-53 is a\nvery general phenomenon, which should be observed in a limited temperature\nrange regardless of the guest molecule. In addition, the previously proposed\nstress model for the structural transitions of MIL-53 is shown to be\ntransferable from xenon to methane adsorption. The stress model also provides a\ntheoretical framework for understanding the existence of lp/np phase mixtures\nat pressures close to the breathing transition pressure, without having to\ninvoke an inhomogeneous distribution of the adsorbate in the porous sample."
    },
    {
        "anchor": "Strong exciton-plasmon coupling in MoS2 coupled with plasmonic lattice: We demonstrate strong exciton-plasmon coupling in silver nanodisk arrays\nintegrated with monolayer MoS2 via angle-resolved reflectance microscopy\nspectra of the coupled system. Strong exciton-plasmon coupling is observed with\nthe exciton-plasmon coupling strength up to 58 meV at 77 K, which also survives\nat room temperature. The strong coupling involves three types of resonances:\nMoS2 excitons, localized surface plasmon resonances (LSPRs) of individual\nsilver nanodisks and plasmonic lattice resonances of the nanodisk array. We\nshow that the exciton-plasmon coupling strength, polariton composition and\ndispersion can be effectively engineered by tuning the geometry of the\nplasmonic lattice, which makes the system promising for realizing novel\ntwo-dimensional plasmonic polaritonic devices.",
        "positive": "Twofold topological phase transitions induced by third-nearest-neighbor\n  interactions in 1D chains: Strong long-range hoppings up to third nearest neighbors may induce a\ntopological phase transition in one-dimensional chains. Unlike the\nSu-Schrieffer-Heeger model, this transition from trivial to topological phase\noccurs with the emergence of a pseudospin valley structure and a twofold\nnontrivial topological phase. Within a tight-binding approach, these\ntopological phases are analyzed in detail and it is shown that the low-energy\nexcitations follow a modified Dirac equation, in which the dynamics of\nparticles with positive and negative mass occur differently. An experimental\nrealization in a one-dimensional elastic chain, where it is feasible to tune\ndirectly the third-nearest-neighbor hoppings, is proposed."
    },
    {
        "anchor": "Studies of single doping of Mn and Fe in Si to deduce simple guidelines\n  in selecting transition metal elements for growing Si-based spintronic\n  materials: Single dopings of Mn and Fe in Si are investigated using 8-, 64-, and\n216-atom supercells and a first-principles method based on density functional\ntheory. Between the two transition metal elements (TMEs), atom sizes play an\nessential role in determining the contraction or the expansion of neighboring\natoms around the TME dopant at a substitutional site. At a tetrahedral\ninterstitial site, there is only expansion. Magnetic moments/TME at the two\nsites are calculated. Physical origins for these inter-related properties are\ndiscussed. A few suggestions about the growth of these Si-based alloys are\ngiven.",
        "positive": "Anisotropic Transport for Parabolic, Non-Parabolic and Linear Bands of\n  Different Dimensions: Anisotropic thermoelectrics is a very interesting topic among recent\nresearch. The transport distribution function plays the central role on\nmodeling the anisotropic thermoelectrics. The methodology of numerical\nintegrations is used in previous literature on anisotropic transport, which\ndoes not capture the sharp change of transport distribution function and\ndensity of states at band edges. However, the sharp change of transport\ndistribution function and density of states at band edges plays the central\nrole in enhancing the thermoelectric performance. Thus, an analytical\nmethodology that is robust on modeling the sharp change of transport\ndistribution function and density of states at a band edges is needed. To our\nbest knowledge, there has not been a paper giving the systematic study on the\nanalytical models of anisotropic transport distribution function for different\nkinds of band valleys in different dimensions under different assumptions.\nTherefore, the main focus of this present paper is to develop such a robust\nanalytical methodology on modeling the anisotropic transport distribution\nfunction. So our contributions are 1) we have developed a systematic method on\nmodel the anisotropic transport distribution function, for 3D, 2D and 1D\nsystems, in parabolic, non-parabolic and linear dispersion relations, under\nboth the relaxation time approximation and the mean free path approximation; 2)\nwe have found that the Onsage's relation of transport can be violated under\ncertain conditions; 3) we have compared our newly developed methodology with\nthe traditional used numerical methodology."
    },
    {
        "anchor": "High Intrinsic Mobility and Ultrafast Carrier Dynamics in Multilayer\n  Metal Dichalcogenide MoS2: The ultimate limitations on carrier mobilities in metal dichalcogenides, and\nthe dynamics associated with carrier relaxation, are unclear. We present\nmeasurements of the frequency-dependent conductivity of multilayer\ndichalcogenide MoS2 by optical-pump terahertz-probe spectroscopy. We find\nmobilities in this material approaching 4200 cm2/Vs at low temperatures. The\ntemperature dependence of scattering indicates that the mobility, an order of\nmagnitude larger than previously reported for MoS2, is intrinsically limited by\nacoustic phonon scattering at THz frequencies. Our measurements of carrier\nrelaxation reveal picosecond cooling times followed by recombination lasting\ntens of nanoseconds and dominated by Auger scattering into defects. Our results\nprovide a useful context in which to understand and evaluate the performance of\nMoS2-based electronic and optoelectronic devices.",
        "positive": "Topological semimetal in honeycomb lattice LnSI: Recognized as elementary particles in the standard model,Weyl fermions in\ncondensed matter have received growing attention. However, most of the\npreviously reportedWeyl semimetals exhibit rather complicated electronic\nstructures that, in turn, may have raised questions regarding the underlying\nphysics. Here, we report for the first time promising topological phases that\ncan be realized in specific honeycomb lattices, including ideal Weyl semimetal\nstructures, 3D strong topological insulators, and nodal-line semimetal\nconfigurations. In particular, we highlight a novel semimetal featuring both\nWeyl nodes and nodal lines. Guided by this model, we demonstrated that GdSI the\nlong perceived ideal Weyl semimetal has two pairs ofWeyl nodes residing at the\nFermi level, and that LuSI (YSI) is a 3D strong topological insulator with the\nright-handed helical surface states. Our work provides a new mechanism to study\ntopological semimetals, and proposes a platform towards exploring the physics\nof Weyl semimetals as well as related device designs."
    },
    {
        "anchor": "Electrostatics of electron-hole interactions in van der Waals\n  heterostructures: The role of dielectric screening of electron-hole interaction in van der\nWaals heterostructures is theoretically investigated. A comparison between\nmodels available in the literature for describing these interactions is made\nand the limitations of these approaches are discussed. A simple numerical\nsolution of Poissons equation for a stack of dielectric slabs based on a\ntransfer matrix method is developed, enabling the calculation of the\nelectron-hole interaction potential at very low computational cost and with\nreasonable accuracy. Using different potential models, direct and indirect\nexciton binding energies in these systems are calculated within Wannier-Mott\ntheory, and a comparison of theoretical results with recent experiments on\nexcitons in two-dimensional materials is discussed.",
        "positive": "Electronic structure of transferred graphene/h-BN van der Waals\n  heterostructures with nonzero stacking angles by nano-ARPES: In van der Waals heterostructures, the periodic potential from the Moir\\'e\nsuperlattice can be used as a control knob to modulate the electronic structure\nof the constituent materials. Here we present a nanoscale angle-resolved\nphotoemission spectroscopy (Nano-ARPES) study of transferred graphene/h-BN\nheterostructures with two different stacking angles of 2.4{\\deg} and 4.3{\\deg}\nrespectively. Our measurements reveal six replicas of graphene Dirac cones at\nthe superlattice Brillouin zone (SBZ) centers. The size of the SBZ and its\nrelative rotation angle to the graphene BZ are in good agreement with Moir\\'e\nsuperlattice period extracted from atomic force microscopy (AFM) measurements.\nComparison to epitaxial graphene/h-BN with 0{\\deg} stacking angles suggests\nthat the interaction between graphene and h-BN decreases with increasing\nstacking angle."
    },
    {
        "anchor": "An investigation of Hertzian contact in soft materials using\n  photoelastic tomography: Hertzian contact of a rigid sphere and a highly deformable soft solid is\ninvestigated using integrated photoelasticity. The experiments are performed by\npressing a styrene sphere of 15 mm diameter against a 44 x 44 x 47 mm$^3$\ncuboid made of 5% wt. gelatin, inside a circular polariscope, and with a range\nof forces. The emerging light rays are processed by considering that the\nretardation of each ray carries the cumulative effect of traversing the\ncontact-induced axisymmetric stress field. Then, assuming Hertzian theory is\nvalid, the retardation is analytically calculated for each ray and compared to\nthe experimental one. Furthermore, a finite element model of the process\nintroduces the effect of finite displacements and strains. Beyond the\nqualitative comparison of the retardation fields, the experimental,\ntheoretical, and numerical results are quantitatively compared in terms of the\nmaximum equivalent stress, surface displacement, and contact radius dimensions.\nA favorable agreement is found at lower force levels, where the assumptions of\nHertz theory hold, whereas deviations are observed at higher force levels. A\nmajor discovery of this work is that at the maximum equivalent stress location,\nall three components of principal stress can be determined experimentally, and\nshow satisfactory agreement with theoretical and numerical ones in our\nmeasurement range. This provides valuable insight into Hertzian contact\nproblems since the maximum equivalent stress controls the initiation of plastic\ndeformation or failure. The measured displacement and contact radii also\nreasonably agree with the theoretical and numerical ones. Finally, the\nlimitations that arise due to the linearization of this problem are explored.",
        "positive": "Measurements of the magnetic properties of conduction electrons: We consider various methods and techniques for measuring electron\nmagnetization and susceptibility, which are used in experimental condensed\nmatter physics. The list of considered methods for macroscopic measurements\nincludes magnetomechanic, electromagnetic, modulation-type, and also\nthermodynamic methods based on the chemical potential variation. We also\nconsider local methods of magnetic measurements based on the spin Hall effects\nand NV-centers. Several scanning probe magnetometers-microscopes are\nconsidered, such as magnetic resonance force microscope, SQUID-microscope, and\nHall microscope. The review focuses on the spin magnetization measurements of\nelectrons in non-magnetic materials and artificial systems, particularly, in\nlow-dimensional electron systems in semiconductors and in nanosystems, which\ncame to the forefront in recent years."
    },
    {
        "anchor": "Excited state properties of point defects in semiconductors and\n  insulators investigated with time-dependent density functional theory: We present a formulation of spin-conserving and spin-flip, hybrid\ntime-dependent density functional theory (TDDFT), including the calculation of\nanalytical forces, which allows for efficient calculations of excited state\nproperties of solid-state systems with hundreds to thousands of atoms. We\ndiscuss an implementation on both GPU and CPU based architectures, along with\nseveral acceleration techniques. We then apply our formulation to the study of\nseveral point defects in semiconductors and insulators, specifically the\nnegatively charged nitrogen-vacancy and neutral silicon-vacancy centers in\ndiamond, the neutral divacancy center in 4H silicon carbide, and the neutral\noxygen-vacancy center in magnesium oxide. Our results highlight the importance\nof taking into account structural relaxations in excited states, in order to\ninterpret and predict optical absorption and emission mechanisms in\nspin-defects.",
        "positive": "Solvent Induced Proton Hopping at a Water-Oxide Interface: Despite widespread interest, a detailed understanding of the dynamics of\nproton transfer at interfaces is lacking. Here we use ab initio molecular\ndynamics to unravel the connection between interfacial water structure and\nproton transfer for the widely studied and experimentally well-characterized\nwater-ZnO$(10\\bar{1}0)$ interface. We find that upon going from a single layer\nof adsorbed water to a liquid multilayer changes in the structure are\naccompanied by a dramatic increase in the proton transfer rate at the surface.\nWe show how hydrogen bonding and rather specific hydrogen bond fluctuations at\nthe interface are responsible for the change in the structure and proton\ntransfer dynamics. The implications of this for the chemical reactivity and for\nthe modelling of complex wet oxide interfaces in general are also discussed."
    },
    {
        "anchor": "Interference effects on the ID/IG ratio of the Raman spectra of\n  diamond-like carbon thin films: Ratio of the intensity of D- Raman peak and G- Raman peak (ID/IG) is often\nused for characterization of diamond-like carbon films, for example to estimate\nnumber and size of the sp2 clusters. In this paper we investigate how the\ninterference effects in the film influence this ratio. It is shown that for\nfilms on silicon substrates the distortion of the real ratio can reach 10 % and\nfor films on metals even 40 %. This should be taken into account if some\nconclusions are made from the measured ID/IG ratio.",
        "positive": "Spin-wave directional anisotropies in antiferromagnetic\n  Ba$_{3}$NbFe$_{3}$Si$_{2}$O$_{14}$: Ba$_{3}$NbFe$_{3}$Si$_{2}$O$_{14}$ (langasite) is structurally and\nmagnetically single domain chiral with the magnetic helicity induced through\ncompeting symmetric exchange interactions. Using neutron scattering, we show\nthat the spin-waves in antiferromagnetic langasite display directional\nanisotropy. On applying a time reversal symmetry breaking magnetic field along\nthe $c$-axis, the spin wave energies differ when the sign is reversed for\neither the momentum transfer $\\pm$ $\\vec{Q}$ or applied magnetic field $\\pm$\n$\\mu_{0}$H. When the field is applied within the crystallographic $ab$-plane,\nthe spin wave dispersion is directionally \\textit{isotropic} and symmetric in\n$\\pm$ $\\mu_{0}$H. However, a directional anisotropy is observed in the spin\nwave intensity. We discuss this directional anisotropy in the dispersion in\nlangasite in terms of a field induced precession of the dynamic unit cell\nstaggered magnetization. Directional anisotropy, or often referred to as non\nreciprocal responses, can occur in antiferromagnetic phases in the absence of\nthe Dzyaloshinskii-Moriya interaction or other effects resulting from\nspin-orbit coupling."
    },
    {
        "anchor": "Modeling Near-Surface Bound Electron States in Three-Dimensional\n  Topological Insulator: Analytical and Numerical Approaches: We apply both analytical and ab-initio methods to explore heterostructures\ncomposed of a threedimensional topological insulator (3D TI) and an ultrathin\nnormal insulator (NI) overlayer as a proof ground for the principles of the\ntopological phase engineering. Using the continual model of a semi-infinite 3D\nTI we study the surface potential (SP) effect caused by an attached ultrathin\nlayer of 3D NI on the formation of topological bound states at the interface.\nThe results reveal that spatial profile and spectrum of these near-surface\nstates strongly depend on both the sign and strength of the SP. Using ab-initio\nband structure calculations to take materials specificity into account, we\ninvestigate the NI/TI heterostructures formed by a single tetradymite-type\nquintuple or septuple layer block and the 3D TI substrate. The analytical\ncontinuum theory results relate the near-surface state evolution with the SP\nvariation and are in good qualitative agreement with those obtained from\ndensity-functional theory (DFT) calculations. We predict also the appearance of\nthe quasi-topological bound state on the 3D NI surface caused by a local band\ngap inversion induced by an overlayer.",
        "positive": "Energy harvesting from coupled bending-twisting oscillations in\n  carbon-fibre reinforced polymer laminates: The energy harvesting capability of resonant harvesting structures, such as\npiezoelectric cantilever beams, can be improved by utilizing coupled\noscillations that generate favourable strain mode distributions. In this work,\nwe present the first demonstration of the use of a laminated carbon fibre\nreinforced polymer to create cantilever beams that undergo coupled\nbending-twisting oscillations for energy harvesting applications. Piezoelectric\nlayers that operate in bending and shear mode are attached to the bend-twist\ncoupled beam surface at locations of maximum bending and torsional strains in\nthe first mode of vibration to fully exploit the strain distribution along the\nbeam. Modelling of this new bend-twist harvesting system is presented, which\ncompares favourably with experimental results. It is demonstrated that the\nvariety of bend and torsional modes of the harvesters can be utilized to create\na harvester that operates over a wider range of frequencies and such\nmulti-modal device architectures provides a unique approach to tune the\nfrequency response of resonant harvesting systems."
    },
    {
        "anchor": "Scaling Properties of Dislocation Simulations in the Similitude Regime: Dislocation systems exhibit well known scaling properties such as the Taylor\nrelationship between flow stress and dislocation density, and the \"law of\nsimilitude\" linking the flow stress to the characteristic wavelength of\ndislocation patterns. Here we discuss the origin of these properties, which can\nbe related to generic invariance properties of the equations of evolution of\ndiscrete dislocation systems, and their implications for a wide class of models\nof dislocation microstructure evolution. We demonstrate that under certain\nconditions dislocation simulations carried out at different stress, dislocation\ndensity, and strain rate can be considered as equivalent, and we study the\nrange of deformation conditions (\"similitude regime\") over which this\nequivalence can be expected to hold. In addition, we discuss the restrictions\nimposed by the formulated invariance properties for density-based, nonlocal or\nstochastic models of dislocation microstructure evolution, and for dislocation\npatterns and size effects.",
        "positive": "Dynamics of thermoelastic thin plates: A comparison of four theories: Four distinct theories describing the flexural motion of thermoelastic thin\nplates are compared. The theories are due to Chadwick, Lagnese and Lions,\nSimmonds, and Norris. Chadwick's theory requires a 3D spatial equation for the\ntemperature but is considered the most accurate as the others are derivable\nfrom it by different approximations. Attention is given to the damping of\nflexural waves. Analytical and quantitative comparisons indicate that the\nLagnese and Lions model with a 2D temperature equation captures the essential\nfeatures of the thermoelastic damping, but contains systematic inaccuracies.\nThese are attributable to the approximation for the first moment of the\ntemperature used in deriving the Lagnese and Lions equation. Simmonds' model\nwith an explicit formula for temperature in terms of plate deflection is the\nsimplest of all but is accurate only at low frequency, where the damping is\nlinearly proportional to the frequency. It is shown that the Norris model,\nwhich is almost as simple as Simmond's, is as accurate as the more precise but\ninvolved theory of Chadwick."
    },
    {
        "anchor": "Graphene Oxidation: Thickness Dependent Etching and Strong Chemical\n  Doping: Patterned graphene shows substantial potential for applications in future\nmolecular-scale integrated electronics. Environmental effects are a critical\nissue in a single layer material where every atom is on the surface. Especially\nintriguing is the variety of rich chemical interactions shown by molecular\noxygen with aromatic molecules. We find that O2 etching kinetics vary strongly\nwith the number of graphene layers in the sample. Three-layer-thick samples\nshow etching similar to bulk natural graphite. Single-layer graphene reacts\nfaster and shows random etch pits in contrast to natural graphite where\nnucleation occurs at point defects. In addition, basal plane oxygen species\nstrongly hole dope graphene, with a Fermi level shift of ~0.5 eV. These oxygen\nspecies partially desorb in an Ar gas flow, or under irradiation by far UV\nlight, and readsorb again in an O2 atmosphere at room temperature. This\nstrongly doped graphene is very different than graphene oxide made by mineral\nacid attack.",
        "positive": "Reversible and irreversible trapping at room temperature in\n  poly(thiophene) thin-film transistors: We measured the bias stress characteristics of poly(thiophene)\nsemi-crystalline thin-film transistors (TFTs) as a function stress times, gate\nvoltages and duty-cycles. At room temperature, the bias stress has two\ncomponents: a fast reversible component and a slow irreversible component. We\nhypothesize that the irreversible component is due to charge trapping in the\ndisordered areas of the semiconductor film. At low duty-cycle (<2%), the fast\nbias stress component is reversed during the off-part of the cycle therefore\nthe observed VT shift in only caused by irreversible trapping. Irreversible\ntrapping follows power-law kinetics with a time exponent approximately equal to\n0.37. We use these findings to estimate the lifetime of TFTs used as switches\nin display backplanes."
    },
    {
        "anchor": "Reconciling results of tunnelling experiments on (Ga,Mn)As: A theoretical model is presented which allows to reconcile findings of\nscanning tunnelling spectroscopy for (Ga,Mn)As [Richardella et al. Science 327,\n66 (2010)] with results for tunneling across (Ga,Mn)As thin layers [Ohya et al.\nNature Phys. 7, 342 (2011); Phys. Rev. Lett. 104, 167204 (2010)]. According to\nthe proposed model, supported by a self-consistent solution of the Poisson and\nSchroedinger equations, a nonmonotonic behaviour of differential tunnel\nconductance as a function of bias is associated with the appearance of\ntwo-dimensional hole subbands rather in the GaAs:Be electrode than in the\n(Ga,Mn)As layer.",
        "positive": "Effects of Grain Boundaries and Defects on Anisotropic Magnon Transport\n  in Textured Sr14Cu24O41: The strong spin-spin exchange interaction in some low-dimensional magnetic\nmaterials can give rise to a high group velocity and thermal conductivity\ncontribution from magnons. One example is the incommensurate layered compounds\n(Sr,Ca,La)14Cu24O41. The effects of grain boundaries and defects on\nquasi-one-dimensional magnon transport in these compounds are not well\nunderstood. Here we report the microstructures and anisotropic thermal\ntransport properties of textured Sr14Cu24O41, which are prepared by solid-state\nreaction followed by spark plasma sintering. Transmission electron microscopy\nclearly reveals nano-layered grains and the presence of dislocations and planar\ndefects. The thermal conductivity contribution and mean free paths of magnons\nin the textured samples are evaluated with the use of a kinetic model for\none-dimensional magnon transport, and found to be suppressed significantly as\ncompared to single crystals at low temperatures. The experimental results can\nbe explained by a one-dimensional magnon-defect scattering model, provided that\nthe magnon-grain boundary scattering mean free path in the anisotropic magnetic\nstructure is smaller than the average length of these nano-layers along the c\naxis. The finding suggests low transmission coefficients for magnons across\ngrain boundaries."
    },
    {
        "anchor": "Unraveling the 3D atomic structure of a suspended graphene/hBN van der\n  Waals heterostructure: In this work we demonstrate that a free-standing van der Waals\nheterostructure, usually regarded as a flat object, can exhibit an intrinsic\nbuckled atomic structure resulting from the interaction between two layers with\na small lattice mismatch. We studied a freely suspended membrane of well\naligned graphene on a hexagonal boron nitride (hBN) monolayer by transmission\nelectron microscopy (TEM) and scanning TEM (STEM). We developed a detection\nmethod in the STEM that is capable of recording the direction of the scattered\nelectron beam and that is extremely sensitive to the local stacking of atoms.\nComparison between experimental data and simulated models shows that the\nheterostructure effectively bends in the out-of-plane direction, producing an\nundulated structure having a periodicity that matches the moir\\'e wavelength.\nWe attribute this rippling to the interlayer interaction and also show how this\naffects the intralayer strain in each layer.",
        "positive": "High entropy alloys and their affinity to hydrogen: from Cantor to\n  platinum group elements alloys: Properties of high entropy alloys are currently in the spotlight due to their\npromising applications. One of the least investigated aspects is the affinity\nof these alloys to hydrogen, its diffusion and reactions. In this study we\napply high-pressure at ambient temperature and investigate stress-induced\ndiffusion of hydrogen into the tructure of high entropy alloys HEA including\nthe famous Cantor alloy as well as less known, but nevertheless important\nplatinum group PGM alloys. By applying X-ray diffraction to samples loaded into\ndiamond anvil cells we perform a comparative investigation of these HEA alloys\nin Ne and H2 pressure-transmitting media. Surprisingly, even under stresses far\nexceeding conventional industrial processes both Cantor and PGM alloys show\nexceptional resistance to hydride formation, on par with widely used industrial\ngrade CuBe alloys. Our observations inspire optimism for practical HEA\napplications in hydrogen-relevant industry and technology e.g. coatings, etc,\nparticularly those related to transport and storage."
    },
    {
        "anchor": "Whats special about Y6; the working mechanism of neat Y6 organic solar\n  cell: Non-fullerene acceptors (NFA) have delivered advance in bulk heterojunction\norganic solar cell efficiencies, with the significant milestone of 20% now in\nsight. However, these materials challenge the accepted wisdom of how organic\nsolar cells work. In this work we present neat Y6 device with efficiency above\n4.5%. We thoroughly investigate mechanisms of charge generation and\nrecombination as well as transport in order to understand what is special about\nY6. Our data suggest Y6 generates bulk free charges, with ambipolar mobility,\nwhich can be extracted in the presence of transport layers",
        "positive": "Long and short range magnetism in the frustrated double perovskite\n  Ba2MnWO6: The structural and magnetic properties of the face-centered cubic double\nperovskite Ba2MnWO6 were investigated using neutron powder diffraction,\nDC-magnetometry, muon spin relaxation and inelastic neutron scattering.\nBa2MnWO6 undergoes Type II long-range antiferromagnetic ordering at a Neel\ntemperature of 8(1) K with a frustration index, f = 8. Inelastic neutron\nscattering was used to identify the magnetic coupling constants J1 and J2,\nwhich were found to equal -0.080 meV and -0.076 meV respectively. This\nindicated that both of the magnetic coupling constants were antiferromagnetic\nwith similar magnitudes, which is in contrast to other known 3d metal double\nperovskites Ba2MWO6. Above the Neel temperature, muon spin relaxation\nmeasurements and inelastic neutron scattering techniques identify a short-range\ncorrelated magnetic state that is similar to that observed in the archetypical\nface-centered cubic lattice antiferromagnet MnO."
    },
    {
        "anchor": "Pressure-Tunable Photonic Band Gaps in an Entropic Colloidal Crystal: Materials adopting the diamond structure possess useful properties in atomic\nand colloidal systems, and are a popular target for synthesis in colloids where\na photonic band gap is possible. The desirable photonic properties of the\ndiamond structure pose an interesting opportunity for reconfigurable matter:\ncan we create a colloidal crystal able to switch reversibly to and from the\ndiamond structure? Drawing inspiration from high-pressure transitions of\ndiamond-forming atomic systems, we design a system of polyhedrally-shaped\nparticles that transitions from diamond to a tetragonal diamond derivative upon\na small pressure change. The transition can alternatively be triggered by\nchanging the shape of the particle in-situ. We propose that the transition\nprovides a reversible reconfiguration process for a potential new colloidal\nmaterial, and draw parallels between this transition and phase behavior of the\natomic transitions from which we take inspiration.",
        "positive": "On the issue of ohmicity of Schottky contacts: An analysis is made of the conditions for ohmic contacts realization in the\ncase of Schottky contacts. Based on the classical notions about the mechanisms\nof current flow, we consider the generalized model of Schottky contact that\ntakes into account the thermionic current of majority charge carriers and\nrecombination current of minority charge carriers in Schottky contacts with a\ndielectric gap. An analysis of the results given by that model made it possible\nto obtain ohmicity criteria for Schottky contacts and compare the conditions\nfor low injection level and ohmicity of Schottky contacts in the case of\nsilicon-based contacts. It is shown that conditions for Schottky contact\nohmicity do not coincide with those for p-n junctions."
    },
    {
        "anchor": "Nonlinear magneto-optic effects in doped graphene and gapped graphene: a\n  perturbative treatment: The nonlinear magneto-optic responses are investigated for gapped graphene\nand doped graphene in a perpendicular magnetic field. The electronic states are\ndescribed by Landau levels, and the electron dynamics in an optical field is\nobtained by solving the density matrix in the equation of motion. In the linear\ndispersion approximation around the Dirac points, both linear conductivity and\nthird order nonlinear conductivities are numerically evaluated for infrared\nfrequencies. The nonlinear phenomena, including third harmonic generation, Kerr\neffects and two photon absorption, and four wave mixing, are studied. All\noptical conductivities show strong dependence on the magnetic field. At weak\nmagnetic fields, our results for doped graphene agree with those in the\nliterature. We also present the spectra of the conductivities of gapped\ngraphene. At strong magnetic fields, the third order conductivities show peaks\nwith varying the magnetic field and the photon energy. These peaks are induced\nby the resonant transitions between different Landau levels. The resonant\nchannels, the positions, and the divergences of peaks are analyzed. The\nconductivities can be greatly modified, up to orders of magnitude. The\ndependence of the conductivities on the gap parameter and the chemical\npotential is studied.",
        "positive": "Immense tunnel magnetoresistance mediated by Coulomb blockade effect and\n  current-driven magnetization reversal in Co clusters embedded in a TiO2\n  matrix: This article was withdrawn by the authors due to misinterpretation of\nexperimental data."
    },
    {
        "anchor": "Gigahertz frequency antiferromagnetic resonance and strong magnon-magnon\n  coupling in the layered crystal CrCl3: We report broadband microwave absorption spectroscopy of the layered\nantiferromagnet CrCl3. We observe a rich structure of resonances arising from\nquasi-two-dimensional antiferromagnetic dynamics. Due to the weak interlayer\nmagnetic coupling in this material, we are able to observe both optical and\nacoustic branches of antiferromagnetic resonance in the GHz frequency range and\na symmetry-protected crossing between them. By breaking rotational symmetry, we\nfurther show that strong magnon-magnon coupling with large tunable gaps can be\ninduced between the two resonant modes.",
        "positive": "CoFeAlB alloy with low damping and low magnetization for spin transfer\n  torque switching: We investigate the effect of Al doping on the magnetic properties of the\nalloy CoFeB. Comparative measurements of the saturation magnetization, the\nGilbert damping parameter $\\alpha$ and the exchange constant as a function of\nthe annealing temperature for CoFeB and CoFeAlB thin films are presented. Our\nresults reveal a strong reduction of the magnetization for CoFeAlB in\ncomparison to CoFeB. If the prepared CoFeAlB films are amorphous, the damping\nparameter $\\alpha$ is unaffected by the Al doping in comparison to the CoFeB\nalloy. In contrast, in the case of a crystalline CoFeAlB film, $\\alpha$ is\nfound to be reduced. Furthermore, the x-ray characterization and the evolution\nof the exchange constant with the annealing temperature indicate a similar\ncrystallization process in both alloys. The data proves the suitability of\nCoFeAlB for spin torque switching properties where a reduction of the switching\ncurrent in comparison with CoFeB is expected."
    },
    {
        "anchor": "The study of magnetic topological semimetals by first principles\n  calculations: Magnetic topological semimetals (TSMs) are topological quantum materials with\nbroken time-reversal symmetry (TRS) and isolated nodal points or lines near the\nFermi level. Their topological properties would typically reveal from the\nbulk-edge correspondence principle as nontrivial surface states such as Fermi\narcs or drumhead states, etc. Depending on the degeneracies and distribution of\nthe nodes in the crystal momentum space, TSMs are usually classified into Weyl\nsemimetals (WSMs), Dirac semimetals (DSMs), nodal-line semimetals (NLSMs),\ntriple-point semimetals (TPSMs), etc. In this review article, we present the\nrecent advances of magnetic TSMs from a computational perspective. We first\nreview the early predicted magnetic WSMs such as pyrochlore iridates and\nHgCr2Se4, as well as the recently proposed Heusler, Kagome layers, and\nhoneycomb lattice WSMs. Then we discuss the recent developments of magnetic\nDSMs, especially CuMnAs in Type-III and EuCd2As2 in Type-IV magnetic space\ngroups (MSGs). Then we introduce some magnetic NLSMs that are robust against\nspin-orbit coupling (SOC), namely Fe3GeTe2 and LaCl (LaBr). Finally, we discuss\nthe prospects of magnetic TSMs and the interesting directions for future\nresearch.",
        "positive": "Photoluminescence clamping with few excitons in a single-walled carbon\n  nanotube: Single air-suspended carbon nanotubes (length 2 - 5 microns) exhibit high\noptical quantum efficiency (7 - 20%) for resonant pumping at low intensities.\nUnder ultrafast excitation, the photoluminescence dramatically saturates for\nvery low injected exciton numbers (2 to 6 excitons per pulse per SWCNT). This\nPL clamping is attributed to highly efficient exciton-exciton annihilation over\nmicron length scales. Stochastic modeling of exciton dynamics and femtosecond\nexcitation correlation spectroscopy allow determination of nanotube absorption\n(2 - 6%) and exciton lifetime (85 +- 20 ps)."
    },
    {
        "anchor": "Extensible Structure-Informed Prediction of Formation Energy with\n  Improved Accuracy and Usability employing Neural Networks: In the present paper, we introduce a new neural network-based tool for the\nprediction of formation energies of atomic structures based on elemental and\nstructural features of Voronoi-tessellated materials. We provide a concise\noverview of the connection between the machine learning and the true\nmaterial-property relationship, how to improve the generalization accuracy by\nreducing overfitting, how new data can be incorporated into the model to tune\nit to a specific material system, and preliminary results on using models to\npreform local structure relaxations.\n  The present work resulted in three final models optimized for (1) highest\ntest accuracy on the Open Quantum Materials Database (OQMD), (2) performance in\nthe discovery of new materials, and (3) performance at a low computational\ncost. On a test set of 21,800 compounds randomly selected from OQMD, they\nachieve a mean absolute error (MAE) of 28, 40, and 42 meV/atom, respectively.\nThe second model provides better predictions in a test case of interest not\npresent in the OQMD, while the third reduces the computational cost by a factor\nof 8.\n  We collect our results in a new open-source tool called SIPFENN\n(Structure-Informed Prediction of Formation Energy using Neural Networks).\nSIPFENN not only improves the accuracy beyond existing models but also ships in\na ready-to-use form with pre-trained neural networks and a GUI interface. By\nvirtue of this, it can be included in DFT calculations routines at nearly no\ncost.",
        "positive": "The quantum paraelectric phase of SrTiO$_3$ from first principles: We demonstrate how the quantum paraelectric ground state of SrTiO$_3$ can be\naccessed via a microscopic $ab~initio$ approach based on density functional\ntheory. At low temperature the quantum fluctuations are strong enough to\nstabilize the paraelectric phase even though a classical description would\npredict a ferroelectric phase. We find that accounting for quantum fluctuations\nof the lattice and for the strong coupling between the ferroelectric soft mode\nand lattice elongation is necessary to achieve quantitative agreement with\nexperimental frequency of the ferroelectric soft mode. The temperature\ndependent properties in SrTiO$_3$ are also well captured by the present\nmicroscopic framework."
    },
    {
        "anchor": "Impurity scattering and quantum confinement in giant magnetoresistance\n  systems: Ab initio calculations for the giant magnetoresistance (GMR) in Co/Cu, Fe/Cr,\nand Fe/Au multilayers are presented. The electronic structure of the\nmultilayers and the scattering potentials of point defects therein are\ncalculated self-consistently. Residual resistivities are obtained by solving\nthe quasi-classical Boltzmann equation including the electronic structure of\nthe layered system, the anisotropic scattering cross sections derived by a\nGreen's function method and the vertex corrections. Furthermore, the influence\nof scattering centers at the interfaces and within the metallic layers is\nincorporated by averaging the scattering cross sections of different impurities\nat various sites. An excellent agreement of experimental and theoretical\nresults concerning the general trend of GMR in Co/Cu systems depending on the\ntype and the position of impurities is obtained. Due to the quantum confinement\nin magnetic multilayers GMR can be tailored as a function of the impurity\nposition. In Co/Cu and Fe/Au systems impurities in the magnetic layer lead to\nhigh GMR values, whereas in Fe/Cr systems defects at the interfaces are most\nefficient to increase GMR.",
        "positive": "Ultra-Broadband Acoustic Metasurface for Manipulating the Reflected\n  Waves: We have designed and experimentally realized an ultra-broadband acoustic\nmetasurface (UBAM) capable of going beyond the intrinsic limitation of\nbandwidth in existing designs of optical/acoustical metasurfaces. Both the\nnumerical and experimental results demonstrate that the UBAM made of\nsubwavelength gratings can manipulate the reflected phase-front within a\nbandwidth larger than 2 octaves. A simple physical model based on the phased\narray theory is developed for interpreting this extraordinary phenomenon as\nwell as obtaining deeper insight to the underlying physics of our design. We\nanticipate the UBAM to open new avenue to the design and application of\nbroadband acoustical devices."
    },
    {
        "anchor": "Effect of Coulomb impurities on the electronic structure of magic angle\n  twisted bilayer graphene: In graphene, charged defects break the electron-hole symmetry and can even\ngive rise to exotic collapse states when the defect charge exceeds a critical\nvalue which is proportional to the Fermi velocity. In this work, we investigate\nthe electronic properties of twisted bilayer graphene (tBLG) with charged\ndefects using tight-binding calculations. Like monolayer graphene, tBLG\nexhibits linear bands near the Fermi level but with a dramatically reduced\nFermi velocity near the magic angle (approximately 1.1{\\deg}). This suggests\nthat the critical value of the defect charge in magic-angle tBLG should also be\nvery small. We find that charged defects give rise to significant changes in\nthe low-energy electronic structure of tBLG. Depending on the defect position\nin the moir\\'e unit cell, it is possible to open a band gap or to induce an\nadditional flattening of the low-energy valence and conduction bands. Our\ncalculations suggest that the collapse states of the two monolayers hybridize\nin the twisted bilayer. However, their in-plane localization remains largely\nunaffected by the presence of the additional twisted layer because of the\ndifferent length scales of the moir\\'e lattice and the monolayer collapse state\nwavefunctions. These predictions can be tested in scanning tunnelling\nspectroscopy experiments.",
        "positive": "Interatomic potential for the calculation of barrier distributions in\n  amorphous oxides: Amorphous oxides are important for implants, optics, and gate insulators.\nUnderstanding the effects of oxide doping is crucial to optimize performance.\nHere we report energy barrier distributions for amorphous tantala and doped\noxides using a new set of computationally efficient, two-body potentials that\nreproduce the structural properties of the samples. The distributions can be\ndirectly compared to experiment and used to calculate physical quantities such\nas internal friction."
    },
    {
        "anchor": "A size-consistent Gr\u00fcneisen-quasiharmonic approach for lattice thermal\n  conductivity: We propose a size-consistent Gr\\\"uneisen-quasiharmonic approach (GQA) to\ncalculate the lattice thermal conductivity $\\kappa_l$ where the Gr\\\"uneisen\nparameters that measure the degree of phonon anharmonicity are calculated\ndirectly using first-principles calculations. This is achieved by identifying\nand modifying two existing equations related to the Slack formulae for\n$\\kappa_l$ that suffer from the size-inconsistency problem when dealing with\nnon-monoatomic primitive cells (where the number of atoms in the primitive cell\n$n$ is greater than one). In conjunction with other thermal parameters such as\nthe acoustic Debye temperature $\\theta_a$ that can also be obtained within the\nGQA, we predict $\\kappa_l$ for a range of materials taken from the diamond,\nzincblende, rocksalt, and wurtzite compounds. The results are compared with\nthat from the experiment and the quasiharmonic Debye model (QDM). We find that\nin general the prediction of $\\theta_a$ is rather consistent among the GQA,\nexperiment, and QDM. However, while the QDM somewhat overestimates the\nGr\\\"uneisen parameters and hence underestimates $\\kappa_l$ for most materials,\nthe GQA predicts the experimental trends of Gr\\\"uneisen parameters and\n$\\kappa_l$ more closely. We expect the GQA with the modified Slack formulae\ncould be used as an effective and practical predictor for $\\kappa_l$,\nespecially for crystals with large $n$.",
        "positive": "Machine learning-assisted close-set X-ray diffraction phase\n  identification of transition metals: Machine learning has been applied to the problem of X-ray diffraction phase\nprediction with promising results. In this paper, we describe a method for\nusing machine learning to predict crystal structure phases from X-ray\ndiffraction data of transition metals and their oxides. We evaluate the\nperformance of our method and compare the variety of its settings. Our results\ndemonstrate that the proposed machine learning framework achieves competitive\nperformance. This demonstrates the potential for machine learning to\nsignificantly impact the field of X-ray diffraction and crystal structure\ndetermination. Open-source implementation:\nhttps://github.com/maxnygma/NeuralXRD."
    },
    {
        "anchor": "Intrinsic Nonlinear Hall Detection of the N\u00e9el Vector for\n  Two-Dimensional Antiferromagnetic Spintronics: The respective unique merit of antiferromagnets and two-dimensional (2D)\nmaterials in spintronic applications inspire us to exploit 2D antiferromagnetic\nspintronics. However, the detection of the N\\'eel vector in 2D antiferromagnets\nremains a great challenge because the measured signals usually decrease\nsignificantly in the 2D limit. Here we propose that the N\\'eel vector of 2D\nantiferromagnets can be efficiently detected by the intrinsic nonlinear Hall\n(INH) effect which exhibits unexpected significant signals. As a specific\nexample, we show that the INH conductivity of the monolayer manganese\nchalcogenides Mn$X$ ($X$=S, Se, Te) can reach the order of nm$\\cdot$mA/V$^2$,\nwhich is orders of magnitude larger than experimental values of paradigmatic\nantiferromagnetic spintronic materials. The INH effect can be accurately\ncontrolled by shifting the chemical potential around the band edge, which is\nexperimentally feasible via electric gating or charge doping. Moreover, we\nexplicitly demonstrate its $2\\pi$-periodic dependence on the N\\'eel vector\norientation based on an effective $k.p$ model. Our findings enable flexible\ndesign schemes and promising material platforms for spintronic memory device\napplications based on 2D antiferromagnets.",
        "positive": "N$_2$H: A Novel Polymeric Hydronitrogen as a High Energy Density\n  Material: The polymeric phase of nitrogen connected by the lower (than three) order N-N\nbonds has been long sought after for the potential application as high energy\ndensity materials. Here we report a hitherto unknown polymeric N$_2$H phase\ndiscovered in the high-pressure hydronitrogen system by first-principle\nstructure search method based on particle swarm optimization algorithm. This\npolymeric hydronitrogen consists of quasi-one-dimensional infinite\narmchair-like polymeric N chains, where H atoms bond with two adjacent N\nlocated at one side of armchair edge. It is energetically stable against\ndecomposition above ~33 GPa, and shows novel metallic feature as the result of\npressure-enhanced charge transfer and delocalization of {\\pi} electrons within\nthe infinite nitrogen chains. The high energy density (~4.40 KJ/g), high\nnitrogen content (96.6%), as well as relatively low stabilization pressure,\nmake it a possible candidate for high energy density applications. It also has\nlattice dynamical stability down to the ambient pressure, allowing for the\npossibility of kinetic stability with respect to variations of external\nconditions. Experimental synthesis of this novel phase is called for."
    },
    {
        "anchor": "Comment on: Evidence and Stability Field of fcc Superionic Water Ice\n  Using Static Compression: Weck et al. (1) report on the existence and stability fields of two\nsuperionic (SI) phases of H2O ice at high P-T (P-T) conditions, which has been\na topic of static and dynamic experiments and theoretical calculations (see\nRef. (2) and references therein). They confirm Ref. (2) in that there are two\nSI phases with bcc and fcc oxygen sublattices with the stability at low- and\nhigh-P. However, they report on an extended stability field of fcc-SI ice\ntoward lower T but no sign of it below 57 GPa. Here we argue that the reported\nphase boundaries of fcc-SI phase are not well experimentally justified due to\ndifficulties to perform adequate X-ray diffraction (XRD) and radiometric\nmeasurements.",
        "positive": "Piezoelectric resonance in Rochelle salt: the contribution of diagonal\n  strains: Within the framework of two-sublattice Mitsui model with taking into account\nthe shear strain $\\varepsilon_4$ and the diagonal strains $\\varepsilon_2$ and\n$\\varepsilon_3$, a dynamic dielectric response of Rochelle salt X-cuts is\nconsidered. Experimentally observed phenomena of crystal clamping by high\nfrequency electric field, piezoelectric resonance and microwave dispersion are\ndescribed. It is shown that the lowest resonant frequency is always associated\nwith the $\\varepsilon_4$ shear mode"
    },
    {
        "anchor": "Cluster Diffusion and Coalescence on Metal Surfaces: applications of a\n  Self-learning Kinetic Monte-Carlo method: The Kinetic Monte Carlo (KMC) method has become an important tool for\nexamination of phenomena like surface diffusion and thin film growth because of\nits ability to carry out simulations for time scales that are relevant to\nexperiments. But the method generally has limited predictive power because of\nits reliance on predetermined atomic events and their energetics as input. We\npresent a novel method, within the lattice gas model in which we combine\nstandard KMC with automatic generation of a table of microscopic events,\nfacilitated by a pattern recognition scheme. Each time the system encounters a\nnew configuration, the algorithm initiates a procedure for saddle point search\naround a given energy minimum. Nontrivial paths are thus selected and the fully\ncharacterized transition path is permanently recorded in a database for future\nusage. The system thus automatically builds up all possible single and multiple\natom processes that it needs for a sustained simulation. Application of the\nmethod to the examination of the diffusion of 2-dimensional adatom clusters on\nCu(111) displays the key role played by specific diffusion processes and also\nreveals the presence of a number of multiple atom processes, whose importance\nis found to decrease with increasing cluster size and decreasing surface\ntemperature. Similarly, the rate limiting steps in the coalescence of adatom\nislands are determined. Results are compared with those from experiments where\navailable and with those from KMC simulations based on a fixed catalogue of\ndiffusion processes.",
        "positive": "Predictive power of polynomial machine learning potentials for liquid\n  states in 22 elemental systems: The polynomial machine learning potentials (MLPs) described by polynomial\nrotational invariants have been systematically developed for various systems\nand used in diverse applications in crystalline states. In this study, we\nsystematically investigate the predictive power of the polynomial MLPs for\nliquid structural properties in 22 elemental systems with diverse chemical\nbonding properties, including those showing anomalous melting behavior, such as\nSi, Ge, and Bi. We compare liquid structural properties obtained from molecular\ndynamics simulations using the density functional theory (DFT) calculation, the\npolynomial MLPs, and other interatomic potentials in the literature. The\ncurrent results demonstrate that the polynomial MLPs consistently exhibit high\npredictive power for liquid structural properties with the same accuracy as\nthat of typical DFT calculations."
    },
    {
        "anchor": "Sharp magnetization step across the ferromagnetic to antiferromagnetic\n  transition in doped-CeFe$_2$ alloys: Very sharp magnetization step is observed across the field induced\nantiferromagnetic to ferromagnetic transition in various doped-CeFe$_2$ alloys,\nwhen the measurement is performed below 5K. In the higher temperature regime\n(T$>$5K) this transition is quite smooth in nature. Comparing with the recently\nobserved similar behaviour in manganites showing colossal magnetoresistance and\nmagnetocaloric material Gd$_5$Ge$_4$ we argue that such magnetization step is a\ngeneralized feature of a disorder influenced first order phase transition.",
        "positive": "Two-photon absorption in two-dimensional materials: The case of\n  hexagonal boron nitride: We calculate the two-photon absorption in bulk and single layer hexagonal\nboron nitride (hBN) both by an ab-initio real-time Bethe-Salpeter approach and\nby a the real-space solution of the excitonic problem in tight-binding\nformalism. The two-photon absorption obeys different selection rules from those\ngoverning linear optics and therefore provides complementary information on the\nelectronic excitations of hBN. Combining the results from the simulations with\na symmetry analysis we show that two-photon absorption is able to probe the\nlowest energy $1s$ states in the single layer hBN and the lowest dark\ndegenerate dark states of bulk hBN. This deviation from the \"usual\" selection\nrules based on the continuous hydrogenic model is explained within a simple\nmodel that accounts for the crystalline symmetry. The same model can be applied\nto other two-dimensional materials with the same point-group symmetry, such as\nthe transition metal chalcogenides. We also discuss the selection rules related\nto the inversion symmetry of the bulk layer stacking."
    },
    {
        "anchor": "Design of Core-Shell Structured Magnetic Microwires with Desirable\n  Properties for Multifunctional Applications: Amorphous Co-rich microwires with excellent soft magnetic and mechanical\nproperties produced by melt-extraction technique are emerging as a\nmultifunctional material for a variety of applications ranging from\nultrasensitive magnetic field sensors to structural health self-monitoring\ncomposites. There is a pressing need for enhancing these properties to make the\nmicrowires practical for integration into new technologies. Conventional heat\ntreatments at temperature below crystallization may improve the magnetic\nsoftness of an as-quenched amorphous wire, but usually deteriorate the good\nmechanical characteristic of the wire due to crystallization. To overcome this,\nwe propose a new approach that utilizes the advantages of a multi-step Joule\ncurrent annealing method to design novel (nanocrystal, amorphous)/amorphous\ncore/shell structures directly from as-quenched amorphous microwires. These\nresults show that the density and size of nanocrystals in the core can be\noptimized by controlling the Joule current intensity, resulting in the large\nenhancement of soft magnetic and giant magneto-impedance properties, while the\namorphous shell preserves the excellent mechanical strength of the microwire.\nThis study also provides a new pathway for the design of novel core/shell\nstructures directly from rapidly quenched amorphous magnetic materials that are\ncurrently exploited in high frequency transformers, sensing and cooling\ndevices.",
        "positive": "Tunable Two-Dimensional Group-III Metal Alloys: Chemically stable quantum-confined 2D metals are of interest in\nnext-generation nanoscale quantum devices. Bottom-up design and synthesis of\nsuch metals could enable the creation of materials with tailored, on-demand,\nelectronic and optical properties for applications that utilize tunable\nplasmonic coupling, optical non-linearity, epsilon-near-zero behavior, or\nwavelength-specific light trapping. In this work, we demonstrate that the\nelectronic, superconducting and optical properties of air-stable\ntwo-dimensional metals can be controllably tuned by the formation of alloys.\nEnvironmentally robust large-area two-dimensional InxGa1-x alloys are\nsynthesized by Confinement Heteroepitaxy (CHet). Near-complete solid solubility\nis achieved with no evidence of phase segregation, and the composition is\ntunable over the full range of x by changing the relative elemental composition\nof the precursor. The optical and electronic properties directly correlate with\nalloy composition, wherein the dielectric function, band structure,\nsuperconductivity, and charge transfer from the metal to graphene are all\ncontrolled by the indium/gallium ratio in the 2D metal layer."
    },
    {
        "anchor": "Visualization of Chiral Electronic Structure and Anomalous Optical\n  Response in a Material with Chiral Charge Density Waves: Chiral materials have attracted significant research interests as they\nexhibit intriguing physical properties, such as chiral optical response,\nspin-momentum locking and chiral induced spin selectivity. Recently, layered\ntransition metal dichalcogenide 1T-TaS2 has been found to host a chiral charge\ndensity wave (CDW) order. Nevertheless, the physical consequences of the chiral\norder, for example, in electronic structures and the optical properties, are\nyet to be explored. Here, we report the spectroscopic visualization of an\nemergent chiral electronic band structure in the CDW phase, characterized by\nwindmill-shape Fermi surfaces. We uncover a remarkable chirality-dependent\ncircularly polarized Raman response due to the salient chiral symmetry of CDW,\nalthough the ordinary circular dichroism vanishes. Chiral Fermi surfaces and\nanomalous Raman responses coincide with the CDW transition, proving their\nlattice origin. Our work paves a path to manipulate the chiral electronic and\noptical properties in two-dimensional materials and explore applications in\npolarization optics and spintronics.",
        "positive": "Novel boron nitride polymorphs with graphite-diamond hybrid structure: Both boron nitride (BN) and carbon (C) have sp, sp2 and sp3 hybridization\nmodes, and thus resulting in a variety of BN and C polymorphs with similar\nstructures, such as hexagonal BN (hBN) and graphite, cubic BN (cBN) and\ndiamond. Here, five types of BN polymorph structures were proposed\ntheoretically, inspired by the graphite-diamond hybrid structures discovered in\nrecent experiment. These BN polymorphs with graphite-diamond hybrid structures\npossessed excellent mechanical properties with combined high hardness and high\nductility, and also exhibited various electronic properties such as\nsemi-conductivity, semi-metallicity, and even one- and two-dimensional\nconductivity, differing from known insulators hBN and cBN. The simulated\ndiffraction patterns of these BN hybrid structures could account for the\nunsolved diffraction patterns of intermediate products composed of \"compressed\nhBN\" and diamond-like BN, caused by phase transitions in previous experiments.\nThus, this work provides a theoretical basis for the presence of these types of\nhybrid materials during phase transitions between graphite-like and\ndiamond-like BN polymorphs."
    },
    {
        "anchor": "How Graphene is Transformed into Regular Graphane Structure: The paper presents the first computational experiment on the transformation\nof a graphene sheet (graphene molecule Cn) into graphane (CH)n of regular\nchairlike structure. The transformation is considered as stepwise hydrogenation\nof the pristine molecule governed with a particular algorithm. A spatial\ndistribution of the number of effectively unpaired electrons NDA over the\ncarbon carcass lays the algorithm foundation. The atomically mapped high rank\nNDA values are taken as pointers of target atoms at each reaction step. A\ncomplete hydrogenation followed by the formation of regular chairlike graphane\nstructure (CH)n is possible if only all the edge carbon atoms at the perimeter\nof pristine sheet are fixed thus simulating a fixed membrane, while the sheet\nis accessible for hydrogen atoms from both side. The calculations were\nperformed within the framework of unrestricted broken symmetry Hartree-Fock\napproach by using semiempirical AM1 technique.",
        "positive": "Double Dirac Semimetals in Three Dimensions: We study a class of Dirac semimetals that feature an eightfold-degenerate\ndouble Dirac point. We show that 7 of the 230 space groups can host such Dirac\npoints and argue that they all generically display linear dispersion. We\nintroduce an explicit tight-binding model for space groups 130 and 135, showing\nthat 135 can host an intrinsic double Dirac semimetal -- one with no additional\ndegeneracies at the Fermi energy. We consider symmetry-lowering perturbations\nand show that uniaxial compressive strain in different directions leads to\ntopologically distinct insulating phases. In addition, the double Dirac\nsemimetal can accommodate topological line defects that bind helical modes.\nPotential materials realizations are discussed."
    },
    {
        "anchor": "Flexocoupling impact on the size effects of piezo- response and\n  conductance in mixed-type ferroelectrics-semiconductors under applied\n  pressure: Flexocoupling impact on the size effects of the spontaneous polarization,\neffective piezo-response, elastic strain and compliance, carrier concentration\nand piezo-conductance have been calculated in thin films of ferroelectric\nsemiconductors with mixed-type conductivity under applied pressure. Analysis of\nthe self-consistent calculation results revealed that the thickness dependences\nof aforementioned physical quantities, calculated at zero and nonzero\nflexoelectric couplings, are very similar under zero applied pressure, but\nbecome strongly different under the application of external pressure pext. At\nthat the differences become noticeably stronger for the film surface under\ncompression than under tension. The impact of the Vegard mechanism on the size\neffects is weaker in comparison with flexocoupling except for the thickness\ndependence of the piezo-conductance. Without flexoelectric coupling the studied\nphysical quantities manifest conventional peculiarities that are characteristic\nof the size-induced phase transitions. Namely, when the film thickness h\napproaches the critical thickness hcr the transition to paraelectric phase\noccurs. The combined effect of flexoelectric coupling and external pressure\ninduces polarizations at the film surfaces, which cause the electric built-in\nfield that destroys the thickness-induced phase transition to paraelectric\nphase at h= hcr and induces the electret-like state with irreversible\nspontaneous polarization at h<hcr. The built-in field leads to noticeable\nincrease of the average strain and elastic compliance under the film thickness\ndecrease below hcr that scales as 1/h at small thicknesses h. The changes of\nthe electron concentration by several orders of magnitude under positive or\nnegative pressures can lead to the occurrence of high- or low-conductivity\nstates, i.e. the nonvolatile piezo-resistive switching.",
        "positive": "Large-Area Two-Dimensional Layered MoTe$_2$ by Physical Vapor Deposition\n  and Solid-Phase Crystallization in a Tellurium-Free Atmosphere: Molybdenum ditelluride (MoTe$_2$) has attracted considerable interest for\nnanoelectronic, optoelectronic, spintronic, and valleytronic applications\nbecause of its modest band gap, high field-effect mobility, large\nspin-orbit-coupling splitting, and tunable 1T'/2H phases. However, synthesizing\nlarge-area, high-quality MoTe$_2$ remains challenging. The complicated design\nof gas-phase reactant transport and reaction for chemical vapor deposition or\ntellurization is nontrivial because of the weak bonding energy between Mo and\nTe. Here, we report a new method for depositing MoTe$_2$ that entails using\nphysical vapor deposition followed by a post-annealing process in a Te-free\natmosphere. Both Mo and Te were physically deposited onto the substrate by\nsputtering a MoTe$_2$ target. A composite SiO$_2$ capping layer was designed to\nprevent Te sublimation during the post-annealing process. The post-annealing\nprocess facilitated 1T'-to-2H phase transition and solid-phase crystallization,\nleading to the formation of high-crystallinity few-layer 2H-MoTe$_2$ with a\nfield-effect mobility of ~10 cm$^2$/(V-s), the highest among all nonexfoliated\n2H-MoTe$_2$ currently reported. Furthermore, 2H-MoS$_2$ and Td-WTe$_2$ can be\ndeposited using similar methods. Requiring no transfer or chemical reaction of\nmetal and chalcogen reactants in the gas phase, the proposed method is\npotentially a general yet simple approach for depositing a wide variety of\nlarge-area, high-quality, two-dimensional layered structures."
    },
    {
        "anchor": "The true corrugation of a h-BN nanomesh layer: Hexagonal boron nitride (h-BN) nanomesh, a two-dimensional insulating\nmonolayer, grown on the (111) surface of rhodium exhibits an intriguing\nhexagonal corrugation pattern with a lattice constant of 3.2 nm. Despite\nnumerous experimental and theoretical studies no quantitative agreement has\nbeen found on some details of the adsorption geometry such as the corrugation\namplitude. The issue highlights the differences in chemical and electronic\nenvironment in the strongly bound pore regions and the weakly bound wire\nregions of the corrugated structure. For reliable results it is important to\nprobe the structure with a method that is intrinsically sensitive to the\nposition of the atomic cores rather than the electron density of states. In\nthis work, we determine the corrugation of h-BN nanomesh from angle- and\nenergy-resolved photoelectron diffraction measurements with chemical state\nresolution. By combining the results from angle and energy scans and comparing\nthem to multiple-scattering simulations true adsorbate-substrate distance can\nbe measured with high precision, avoiding pitfalls of apparent topography\nobserved in scanning probe techniques. Our experimental results give accurate\nvalues for the peak to peak corrugation amplitude (0.80 A), the bonding\ndistance to the substrate (2.20 A) and the buckling of the boron and nitrogen\natoms in the strongly bound pore regions (0.07 A). The results are important\nfor the development of theoretical methods involving the quantitative\ndescription of van der Waals systems like it requires the understanding of the\nphysics of two-dimensional sp2 layers.",
        "positive": "Cu/Ag EAM Potential Optimized for Heteroepitaxial Diffusion from ab\n  initio Data: A binary embedded-atom method (EAM) potential is optimized for Cu on Ag(111)\nby fitting to ab initio data. The fitting database consists of DFT calculations\nof Cu monomers and dimers on Ag(111), specifically their relative energies,\nadatom heights, and dimer separations. We start from the Mishin Cu-Ag EAM\npotential and first modify the Cu-Ag pair potential to match the FCC/HCP site\nenergy difference then include Cu-Cu pair potential optimization for the entire\ndatabase. The optimized EAM potential reproduce DFT monomer and dimer relative\nenergies and geometries correctly. In trimer calculations, the potential\nproduces the DFT relative energy between FCC and HCP trimers, though a\ndifferent ground state is predicted. We use the optimized potential to\ncalculate diffusion barriers for Cu monomers, dimers, and trimers. The\npredicted monomer barrier is the same as DFT, while experimental barriers for\nmonomers and dimers are both lower than predicted here. We attribute the\ndifference with experiment to the overestimation of surface adsorption energies\nby DFT and a simple correction is presented. Our results show that the\noptimized Cu-Ag EAM can be applied in the study of larger Cu islands on\nAg(111)."
    },
    {
        "anchor": "What is moving in silica at 1 K? A computer study of the low-temperature\n  anomalies: Though the existence of two-level systems (TLS) is widely accepted to explain\nlow temperature anomalies in many physical observables, knowledge about their\nproperties is very rare. For silica which is one of the prototype glass-forming\nsystems we elucidate the properties of the TLS via computer simulations by\napplying a systematic search algorithm. We get specific information in the\nconfiguration space, i.e. about relevant energy scales, the absolute number of\nTLS and electric dipole moments. Furthermore important insight about the\nreal-space realization of the TLS can be obtained. Comparison with experimental\nobservations is included.",
        "positive": "Cooperative ordering of superparamagnetic ZnO nanograins: In this paper we have tried to understand the precise nature of magnetism in\nZnO nanoparticles. Cooling field dependence of magnetic hysteresis and coercive\nfield was observed for high temperature annealed sample indicating cooperative\nmagnetic correlation and ordering within the agglomerated nanograins. The\nincreasing induced internal magnetic field along the direction of external\nfield for the high temperature annealed sample has been fitted with the\nmodified Weiss-Brillouin model indicating emergence of long range intergrain\ninteraction among the superparamagnetic grains. We propose a simple idea that\nexplains the reduction of magnetisation due to vortex state like flux closure\nsituation."
    },
    {
        "anchor": "\"Butterfly Effect\" in Shear-Banding Mediated Plasticity of Metallic\n  Glasses: Metallic glasses response to the mechanical stress in a complex and\ninhomogeneous manner with plastic strain highly localized into nanoscale shear\nbands. Contrary to the well-defined deformation mechanism in crystalline\nsolids, understanding the mechanical response mechanism and its intrinsic\ncorrelation with the macroscopical plasticity in metallic glasses remains\nlong-standing issues. Through a combination of experimental and theoretical\nanalysis, we showed that the shear banding process in metallic glasses exhibits\ncomplex chaotic dynamics, which manifests as the existence of a torus destroyed\nphase diagram, a positive Lyapunov exponent and a fractional Lyapunov\ndimension. We also demonstrated that the experimentally observed large\nplasticity fluctuation of metallic glasses tested at the same conditions can be\ninterpreted from the chaotic shear-band dynamics, which could leads to an\nuncertainty on the appearance of the critical condition for runaway shear\nbanding. Physically, the chaotic shear-band dynamics arises from the interplay\nbetween structural disordering and temperature rise within the shear band. By\ntuning the deformation parameters, the chaotic dynamics can be transformed to a\nperiodic orbit state corresponding to a smaller plasticity fluctuation in\nmetallic glasses. Our results suggest that the plastic flow of metallic glasses\nis a complex dynamic process, which is highly sensitive to initial conditions\nand reminiscent of the \"butterfly effect\" as observed in many complex dynamic\nsystems.",
        "positive": "Manipulating electronic states at oxide interfaces using focused micro\n  X-rays from standard lab-sources: Recently, x-ray illumination, using synchrotron radiation, has been used to\nmanipulate defects, stimulate self-organization and to probe their structure.\nHere we explore a method of defect-engineering low-dimensional systems using\nfocused laboratory-scale X-ray sources. We demonstrate an irreversible change\nin the conducting properties of the 2-dimensional electron gas at the interface\nbetween the complex oxide materials LaAlO3 and SrTiO3 by X-ray irradiation. The\nelectrical resistance is monitored during exposure as the irradiated regions\nare driven into a high resistance state. Our results suggest attention shall be\npaid on electronic structure modification in X-ray spectroscopic studies and\nhighlight large-area defect manipulation and direct device patterning as\npossible new fields of application for focused laboratory X-ray sources."
    },
    {
        "anchor": "Comment on \"First order amorphous-amorphous transformation in silica\": In a recent letter (Phys. Rev. Lett. 84, 4629 (2000)), Lacks presents\nevidence of a first order amorphous-amorphous transition in silica at T=0. He\ncalculates the free energy along a path of compression and successive\ndecompression of a sample of 108 SiO2 units. The free energy of the two\nbranches cross each other, and this is interpreted as evidence of a first order\ntransition. We show that this conclusion does not follow from the shown data,\nsince qualitatively the same phenomenology is obtained in a model where a first\norder transition does not exist.",
        "positive": "Photoluminescence from Bi5(GaCl4)3 molecular crystal: Bi5(GaCl4)3 sample has been synthesized through the oxidation of Bi metal by\ngallium chloride (GaCl3) salt. Powder X-ray diffraction as well as micro-Raman\nscattering results revealed that, in addition to crystalline Bi5(GaCl4)3 in the\nproduct, amorphous phase containing [GaCl4]- and [Ga2Cl7]- units also exist.\nThe thorough comparison of steady-state and time-resolved photoluminescent\nbehaviors between Bi5(GaCl4)3 product and Bi5(AlCl4)3 crystal leads us to\nconclude that Bi53+ is the dominant emitter in the product, which gives rise to\nthe ultrabroad emission ranging from 1 to 2.7 micrometer. Detailed quantum\nchemistry calculation helps us assign the observed excitations to some\nelectronic transitions of Bi53+ polycation, especially at shorter wavelengths.\nIt is believed that our work shown here not only is helpful to solve the\nconfusions on the luminescent origin of bismuth in other material systems, but\nalso serves to develop novel broadband tunable laser materials."
    },
    {
        "anchor": "Emergence of a Non-van der Waals Magnetic Phase in a van der Waals\n  Ferromagnet: Manipulation of long-range order in two-dimensional (2D) van der Waals (vdW)\nmagnetic materials (e.g., CrI$_3$, CrSiTe$_3$ etc.), exfoliated in few-atomic\nlayer, can be achieved via application of electric field,\nmechanical-constraint, interface engineering, or even by chemical\nsubstitution/doping. Usually, active surface oxidation due to the exposure in\nthe ambient condition and hydrolysis in the presence of water/moisture causes\ndegradation in magnetic nanosheets which, in turn, affects the\nnanoelectronic/spintronic device performance. Counterintuitively, our current\nstudy reveals that exposure to the air at ambient atmosphere results in advent\nof a stable nonlayered secondary ferromagnetic phase in the form of\nCr$_2$Te$_3$ (T$_{C2}$ ~ 160 K) in the parent vdW magnetic semiconductor\nCr$_2$Ge$_2$Te$_6$ (T$_{C1}$ ~ 69 K). In addition, the magnetic anisotropy\nenergy (MAE) enhances in the hybrid by an order from the weakly anisotropic\npristine Cr$_2$Ge$_2$Te$_6$ crystal, increasing the stability of the FM ground\nstate with time. Comparing with the freshly prepared Cr$_2$Ge$_2$Te$_6$, the\ncoexistence of the two ferromagnetic phases in the time elapsed bulk crystal is\nconfirmed through systematic investigation of crystal structure along with\ndetailed dc/ac magnetic susceptibility, specific heat, and magnetotransport\nmeasurement. To capture the concurrence of the two ferromagnetic phases in a\nsingle material, Ginzburg-Landau theory with two independent order parameters\n(as magnetization) with a coupling term can be introduced. In contrast to\nrather common poor environmental stability of the vdW magnets, our results open\npossibilities of finding air-stable novel materials having multiple magnetic\nphases.",
        "positive": "Computer simulation of the microstructure and rheology of semi-solid\n  alloys under shear: The rheological behavior of metallic alloys containing both solid and liquid\nphases is investigated in the low solid fraction range (<50%). This behavior\ndepends on both the solid fraction and the shear rate. The concept of Effective\nVolume Fraction (EVF) is used to decorrelate the influence of these two\nparameters. At high shear rate the slurry behaves like a suspension of hard\nspheres, whereas at lower shear rate, particles tend to aggregate in clusters,\nentrapping liquid and thus, increasing the EVF and the viscosity. A lattice\nmodel is introduced to simulate the aggregation / break-up processes within a\nslurry under shear. When the steady state is reached, the entrapped liquid\nfraction is calculated, leading to a viscosity estimation. Simulation results\nfor the viscosity and 3D cluster structure are in good agreement with\nexperimental results."
    },
    {
        "anchor": "'Spillout' effect in gold nanoclusters embedded in c-Al2O3(0001) matrix: Gold nanoclusters are grown by 1.8 MeV Au^\\sup{2+} implantation on\nc-Al\\sub{2}O\\sub{3}(0001)substrate and subsequent air annealing at temperatures\n1273K. Post-annealed samples show plasmon resonance in the optical (561-579 nm)\nregion for average cluster sizes ~1.72-2.4 nm. A redshift of the plasmon peak\nwith decreasing cluster size in the post-annealed samples is assigned to the\n'spillout' effect (reduction of electron density) for clusters with ~157-427\nnumber of Au atoms fully embedded in crystalline dielectric matrix with\nincreased polarizability in the embedded system.",
        "positive": "Interface dipoles of organic molecules on Ag(111) in hybrid\n  density-functional theory: We investigate the molecular acceptors 3,4,9,10-perylene-tetracarboxylic acid\ndianhydride (PTCDA), 2,3,5,6-tetra uoro-7,7,8,8-tetracyanoquinodimethane\n(F4TCNQ), and 4,5,9,10-pyrenetetraone (PYTON) on Ag(111) using\ndensityfunctional theory. For two groups of the HSE(\\alpha, \\omega) family of\nexchange-correlation functionals (\\omega = 0 and \\omega = 0.2\\AA) we study the\nisolated components as well as the combined systems as a function of the amount\nof exact-exchange (\\alpha). We find that hybrid functionals favour electron\ntransfer to the adsorbate. Comparing to experimental work-function data, we\nreport for (\\alpha) ca. 0.25 a notable but small improvement over (semi)local\nfunctionals for the interface dipole. Although Kohn-Sham eigenvalues are only\napproximate representations of ionization energies, incidentally, at this value\nalso the density of states agrees well with the photoelectron spectra. However,\nincreasing (\\alpha) to values for which the energy of the lowest unoccupied\nmolecular orbital matches the experimental electron affinity in the gas phase\nworsens both the interface dipole and the density of states. Our results imply\nthat semi-local DFT calculations may often be adequate for conjugated organic\nmolecules on metal surfaces and that the much more computationally demanding\nhybrid functionals yield only small improvements."
    },
    {
        "anchor": "Mode-selective vibrational control of charge transport in\n  $\u03c0$-conjugated molecular materials: The soft character of organic materials leads to strong coupling between\nmolecular nuclear and electronic dynamics. This coupling opens the way to\ncontrol charge transport in organic electronic devices by inducing molecular\nvibrational motions. However, despite encouraging theoretical predictions,\nexperimental realization of such control has remained elusive. Here we\ndemonstrate experimentally that photoconductivity in a model organic\noptoelectronic device can be controlled by the selective excitation of\nmolecular vibrations. Using an ultrafast infrared laser source to create a\ncoherent superposition of vibrational motions in a pentacene/C60 photoresistor,\nwe observe that excitation of certain modes in the 1500-1700 cm$^{-1}$ region\nleads to photocurrent enhancement. Excited vibrations affect predominantly\ntrapped carriers. The effect depends on the nature of the vibration and its\nmode-specific character can be well described by the vibrational modulation of\nintermolecular electronic couplings. Vibrational control thus presents a new\ntool for studying electron-phonon coupling and charge dynamics in\n(bio)molecular materials.",
        "positive": "Influence of incommensurate structure on the elastic constants of\n  crystalline Bi$_2$Sr$_2$CaCu$_2$O$_{8+\u03b4}$ by Brillouin light scattering\n  spectroscopy: Brillouin light scattering spectroscopy was used to probe the\nroom-temperature elasticity of crystalline high-$T_c$ superconductor\nBi$_2$Sr$_2$CaCu$_2$O$_{8+\\delta}$. A complete set of best-estimate elastic\nconstants was obtained using established relationships between acoustic phonon\nvelocities and elastic constants along with a simple expression relating\ncrystal elastic constant $C_{22}$ to the corresponding constants of the\nconstituent incommensurate sublattices. This latter relationship, which was\nderived and validated in the present work, has important implications for those\nstudying incommensurate systems as it appears that it may be applied in its\ngeneral form to any composite incommensurate crystal. The results obtained in\nthis work are also consistent with sublattice assignments of Bi$_2$Sr$_2$O$_4$\nand CaCu$_2$O$_4$ reported in a previous Brillouin scattering study."
    },
    {
        "anchor": "Magnetization dynamics of cobalt grown on graphene: Ferromagnetic resonance (FMR) spin pumping is a rapidly growing field which\nhas demonstrated promising results in a variety of material systems. This\ntechnique utilizes the resonant precession of magnetization in a ferromagnet to\ninject spin into an adjacent non-magnetic material. Spin pumping into graphene\nis attractive on account of its exceptional spin transport properties. This\narticle reports on FMR characterization of cobalt grown on CVD graphene and\nexamines the validity of linewidth broadening as an indicator of spin pumping.\nIn comparison to cobalt samples without graphene, direct contact\ncobalt-on-graphene exhibits increased FMR linewidth--an often used signature of\nspin pumping. Similar results are obtained in Co/MgO/graphene structures, where\na 1nm MgO layer acts as a tunnel barrier. However, SQUID, MFM, and Kerr\nmicroscopy measurements demonstrate increased magnetic disorder in cobalt grown\non graphene, perhaps due to changes in the growth process and an increase in\ndefects. This magnetic disorder may account for the observed linewidth\nenhancement due to effects such as two-magnon scattering or mosaicity. As such,\nit is not possible to conclude successful spin injection into graphene from FMR\nlinewidth measurements alone.",
        "positive": "Appearance of ferromagnetism in Pt(100) ultrathin films originated from\n  quantum-well states: Ferromagnetism was observed in a Pt(100) ultrathin film deposited on a\nSrTiO3(100) substrate. The ferromagnetism, which appears in films with\nthicknesses of 2.2-4.4 nm, periodically changes with a period of approximately\n1 nm (5-6 monolayers) depending on the film thickness. This is consistent with\nthe period derived from the quantum-well states formed in the thin film. X-ray\nmagnetic circular dichroism measurements show the evidence of appearance of\nintrinsic ferromagnetism in Pt(100) ultra-thin film. In addition, present\nresults suggest a possibility that the orbital magnetic moment of pure Pt is\nmuch smaller than that of the Pt/ferromagnetic multilayer system. These results\nwill provide a potential new mechanism for origin of the large magnetic\nanisotropy in Pt components."
    },
    {
        "anchor": "Phonon softening near topological phase transitions: Topological phase transitions occur when the electronic bands change their\ntopological properties, typically featuring the closing of the bandgap. While\nthe influence of topological phase transitions on electronic and optical\nproperties has been extensively studied, its implication on phononic properties\nand thermal transport remains unexplored. In this work, we use first-principles\nsimulations to show that certain phonon modes are significantly softened near\ntopological phase transitions, leading to increased phonon-phonon scattering\nand reduced lattice thermal conductivity. We demonstrate this effect using two\nmodel systems: pressure-induced topological phase transition in $\\rm ZrTe_5$\nand chemical composition induced topological phase transition in\n$\\rm{Hg_{1-x}Cd_{x}Te}$. We attribute the phonon softening to emergent Kohn\nanomalies associated with the closing of the bandgap. Our study reveals the\nstrong connection between electronic band structures and lattice instabilities\nand opens up a potential direction towards controlling heat conduction in\nsolids.",
        "positive": "Compaction dynamics of metallic nano-foams: A hydrodynamics simulation\n  study: The compression of a low-density copper foam was simulated with a radiation,\nhydrodynamics code. In one simulation, the foam had a density of $\\rho_0 =\n1.3407$ g/cm$^3$, 15% the density of copper at standard temperature and\npressure, and was composed of a tangle of standard density cylindrical copper\nfilaments with a diameter of $4.0\\times10^{-7}$ cm. In another simulation, the\nfoam was a uniform material at the same density. The propagation velocity of\nthe shock wave ($U_f$) through the foam was measured and compared with\nexperimental results. The simulations show approximately the same agreement\nwith experimental results for $U_f$ and agreed with estimates from different\nequations of state and simulations using molecular dynamics. Behavior of the\nfoam ahead of the shock wave is also discussed where the porous nature of the\nfoam allows for the formation of a vapor precursor."
    },
    {
        "anchor": "Step Stone Effect: A sp anti-bonding Mediated Long-Range Ferromagnetism\n  in Cr-doped Carrier-Free Bi2Te3: Despite the recent success in the realization of the quantum anomalous Hall\neffect, the underlying physical mechanism of the long range Ferromagnetism is\nstill unclear. Based on our density functional theory calculations, we\ndiscovered an intriguing long-range ferromagnetic order in Cr-doped,\ncarrier-free Bi2Te3, with the separation between dopants more than 8 {\\AA}. We\nfound that this magnetic coupling is facilitated by an anti-bonding state\noriginated from the lone pair of a Te 5p state and a Bi 6s state, despite this\nanti-bonding state lies below the valence band maximum. Such a state serves as\na hidden step stone merged in the electron sea and mediates the long-range\nmagnetic order. An effective electron hopping model is proposed to explain this\nmechanism. This novel mechanism sheds light on the understanding of long-range\nferromagnetism in insulators and may lead to the realization of the long-range\nmagnetic order in dilute magnetic semiconductors.",
        "positive": "Tunneling Spectroscopy of Atomically-Thin Al2O3 Films for Tunnel\n  Junctions: Metal-Insulator-Metal tunnel junctions (MIMTJ) are common throughout the\nmicroelectronics industry. The industry standard AlOx tunnel barrier, formed\nthrough oxygen diffusion into an Al wetting layer, is plagued by internal\ndefects and pinholes which prevent the realization of atomically-thin barriers\ndemanded for enhanced quantum coherence. In this work, we employed in situ\nscanning tunneling spectroscopy (STS) along with molecular dynamics simulations\nto understand and control the growth of atomically thin Al2O3 tunnel barriers\nusing atomic layer deposition (ALD). We found that a carefully tuned initial\nH2O pulse hydroxylated the Al surface and enabled the creation of an\natomically-thin Al2O3 tunnel barrier with a high quality M-I interface and a\nsignificantly enhanced barrier height compared to thermal AlOx. These\nproperties, corroborated by fabricated Josephson Junctions, show that ALD Al2O3\nis a dense, leak-free tunnel barrier with a low defect density which can be a\nkey component for the next-generation of MIMTJs."
    },
    {
        "anchor": "Nanoscale characterisation of hydrides and secondary phase particles in\n  Zircaloy-4: The interaction of hydrogen and metals continues to be industrially relevant\nand is a critical part of creating and supporting a safety case for nuclear\nreactor operation. In the present work, we explore hydrogen storage and hydride\nformation in a zirconium alloy. We characterise the structure and interfaces of\nfine scale hydrides using scanning transmission electron microscopy (STEM)\nincluding energy dispersive spectroscopy (EDS/EDX), electron energy loss\nspectroscopy (EELS), and high-resolution STEM. Chemical characterisation is\nsupported further with atom probe tomography (APT). Samples were prepared with\ncryo-focussed ion beam machining (cryo-FIB) and contain hydrides in {\\alpha}-Zr\nmatrix and hydrides associated with one FeCrZr secondary phase particle (SPP).\nMajor findings include characterisation of different interface planes based\nupon the size of the hydrides and chemical redistribution of solute ahead of\nthe hydride-metal interface. We also find significant (up to 6 at%) hydrogen\nretained in solution within the zirconium matrix and show a hydride with only\n17 at% hydrogen, which is well below that of a {\\xi}-phase stoichiometry\nsuggesting it is an embryonic hydride. These findings help us understand the\ndistribution of hydrogen and the nanoscale morphology of hydrides, which may\ninfluence the lifetime of zirconium-based nuclear fuel cladding.",
        "positive": "Evaluating Computational Shortcuts in Supercell-Based Phonon\n  Calculations of Molecular Crystals: The Instructive Case of Naphthalene: Phonons crucially impact a variety of properties of organic semiconductor\nmaterials. For instance, charge- and heat transport depend on low-frequency\nphonons, while for other properties, such as the free energy, especially\nhigh-frequency phonons count. For all these quantities one needs to know the\nentire phonon band structure, whose simulation becomes exceedingly expensive\nfor more complex systems when using methods like dispersion-corrected density\nfunctional theory (DFT). Therefore, in the present contribution we evaluate the\nperformance of more approximate methodologies, including density functional\ntight binding (DFTB) and a pool of force fields (FF) of varying complexity and\nsophistication. Beyond merely comparing phonon band structures, we also\ncritically evaluate to what extent derived quantities, like\ntemperature-dependent heat capacities, mean squared thermal displacements and\ntemperature-dependent free energies are impacted by shortcomings in the\ndescription of the phonon bands. As a benchmark system, we choose (deuterated)\nnaphthalene, as the only organic semiconductor material for which to date\nexperimental phonon band structures are available in the literature. Overall,\nthe best performance amongst the approximate methodologies is observed for a\nsystem-specifically parametrized second-generation force field. Interestingly,\nin the low-frequency regime also force fields with a rather simplistic model\nfor the bonding interactions (like the General Amber Force Field) perform\nrather well. As far as the tested DFTB parametrization is concerned, we obtain\na significant underestimation of the unit cell volume resulting in a pronounced\noverestimation of the phonon energies in the low frequency region. This cannot\nbe mended by relying on the DFT-calculated unit cell, since with this unit cell\nthe DFTB phonon frequencies significantly underestimate the experiments."
    },
    {
        "anchor": "Effects of Ferromagnetic Magnetic Ordering and Phase Transition on the\n  Resistivity of Spin Current: It has been shown experimentally a long time ago that the magnetic ordering\ncauses an anomalous behavior of the electron resistivity in ferromagnetic\ncrystals. Phenomenological explanations based on the interaction between\nitinerant electron spins and lattice spins have been suggested to explain these\nobservations. We show by extensive Monte Carlo simulation that this behavior is\nalso observed for the resistivity of the spin current calculated as a function\nof temperature ($T$) from low-$T$ ordered phase to high-$T$ paramagnetic phase\nin a ferromagnet. We show in particular that across the critical region, the\nspin resistivity undergoes a huge peak. The origin of this peak is shown to\nstem from the formation of magnetic domains near the phase transition. The\nbehavior of the resistivity obtained here is compared to experiments and\ntheories. A good agreement is observed.",
        "positive": "Molecular dynamics simulations of the growth of thin amorphous\n  hydrogenated carbon films on diamond surface: The growth of thin amorphous hydrogenated carbon films (a-C:H) on diamond\n(111) surface from the bombardment of CH2 radicals is studied using molecular\ndynamics simulations. The structural analysis shows that the local structure\n(e.g., the first coordination number of C atoms) of a-C:H depends critically on\nthe content of hydrogen. The increase of kinetic energy of incident radicals\nleads to the decrease of hydrogen content, which subsequently changes the ratio\nof sp3 bonded C atoms in a-C:H."
    },
    {
        "anchor": "Incommensurate-commensurate magnetic phase transition in the double\n  tungstate Li2Co(WO4)2: Magnetic susceptibility, specific heat, and neutron powder diffraction\nmeasurements have been performed on polycrystalline Li2Co(WO4)2 samples. Under\nzero magnetic field, two successive magnetic transitions at TN1 ~ 9.4 K and TN2\n~ 7.4 K are observed. The magnetic ordering temperatures gradually decrease as\nthe magnetic field increases. Neutron diffraction reveals that Li2Co(WO4)2\nenters an incommensurate magnetic state with a temperature dependent k between\nTN1 and TN2. The magnetic propagation vector locks-in to a commensurate value k\n= (1/2, 1/4, 1/4) below TN2. The antiferromagnetic structure is refined at 1.7\nK with Co2+ magnetic moment 2.8(1) uB, consistent with our first-principles\ncalculations.",
        "positive": "Photocatalytic Activity of Phosphorene Derivatives: Coverage,\n  Electronic, Optical and Excitonic properties: In the context of two-dimensional metal-free photocatalyst, we investigate\nthe electronic, optical and excitonic properties of phosphorene derivatives\nwithin first-principles approach. While two-dimensional phosphorene does not\ncatalyze the complete water splitting reactions, O, S, and N coverages improve\nthe situation drastically, and become susceptible to catalyze the complete\nreaction at certain coverages. We find that for all these dopants, 0.25 -- 0.5\nML coverages are thermodynamically more stable, and does not introduce midgap\ndefect states and the composite systems remain semiconducting along with\nproperly aligned valance and conduction bands. Further, within visible light\nexcitation, the optical absorption remain very high 10$^5$ cm$^{-1}$ in these\ncomposite systems, and the fundamental optical anisotropy of phosphorene\nremains intact. We also investigate the effect of layer thickness through\nbilayer phosphorene with oxygen coverages. Finally we investigate the excitonic\nproperties in these composite materials that are conducive to both redox\nreactions. The present results will open up new avenues to take advantage of\nthese metal-free phosphorene derivatives toward its outstanding potential in\nphotocatalysis."
    },
    {
        "anchor": "Hindered rotation of H2 adsorbed interstitially in nanotube bundles: A theoretical study on the rotational dynamics of H2 molecules trapped in the\ninterstitial channels (ICs) of a carbon nanotube bundle is presented. The\npotential used in this study is modeled as a sum of atom-atom (C-H) van der\nWaals interactions and electrostatic interactions of the molecule with the\nsurrounding nanotubes.The rotational energy spectra is calculated using a\nproduct wave function, where the coupling between translational and rotational\nmodes is treated in a mean-field manner . Molecular dynamics (MD) simulation\nstudy was performed for estimating the hydrogen rotational barrier. Both\ntheoretical calculations and simulation results reveal the existence of a large\nrotational barrier (~ 40 meV). The consequences of this rotational barrier for\nthe rotational energy levels are worked out in detail.",
        "positive": "Bridging the gap between atomistic and macroscopic models of homogeneous\n  nucleation: Macroscopic theories of nucleation such as classical nucleation theory\nenvision that clusters of the bulk stable phase form inside the bulk metastable\nphase. Molecular dynamics simulations are often used to elucidate nucleation\nmechanisms, by capturing the microscopic configurations of all the atoms. In\nthis letter, we introduce a thermodynamic model that links macroscopic theories\nand atomic-scale simulations and thus provide a simple and elegant framework\nfor testing the limits of classical nucleation theory."
    },
    {
        "anchor": "Microstructure effects on the thermal fatigue of solder joints: coupling\n  damage measurements with multi-scale modelling: Thermal fatigue is a common failure mode in electronic solder joints, yet the\nrole of microstructure is incompletely understood. Here, we quantify the\nevolution of microstructure and damage in Sn-3Ag-0.5Cu joints throughout a ball\ngrid array (BGA) package using electron backscatter diffraction (EBSD) mapping\nof localised subgrains, recrystallisation and heavily coarsened Ag3Sn. We then\ninterpret the results with a multi-scale modelling approach that links from a\ncontinuum model at the package/board scale through to a crystal plasticity\nfinite element model at the microstructure scale accounting for the anisotropic\nthermal expansion, elastic and plastic properties of beta-Sn with embedded\nAg3Sn and Cu6Sn5 particles. We measure and explain the dependence of damage\nevolution on (i) the beta-Sn crystal orientation(s) in single and multigrain\njoints, and (ii) the coefficient of thermal expansion (CTE) mismatch between\ntin grains in cyclic twinned multigrain joints. We further explore the relative\nimportance of the solder microstructure versus the joint location in the array.\nThe results provide a basis for designing optimum solder joint microstructures\nfor thermal fatigue resistance.",
        "positive": "Advantages and developments of Raman spectroscopy for electroceramics: Despite being applied with success in many fields of materials science, Raman\nspectroscopy is not yet determinant in the study of electroceramics. Recent\nexperimental and theoretical developments, however, should increase the\npopularity of Raman spectroscopy in this class of materials. In this Review, we\noutline the fields of application of Raman spectroscopy and microscopy in\nvarious electroceramic systems, defining current key bottlenecks and explaining\npromising recent developments. We focus our attention to recent experimental\ndevelopments, including coupling Raman spectroscopy with other methodologies,\nand modelling approaches involving both the model-based data interpretation and\nthe ab initio calculation of realistic Raman spectra."
    },
    {
        "anchor": "Tuning of Magnetic and Electrical Properties in Complex oxide Thin Films\n  Deposited By Pulsed Laser Deposition: Lanthanum manganite, LaMnO (LMO) is the parent compound for a class of hole\ndoped(e.g. La1-xCaxMnO3, La1-xSrxMnO3) and electron doped (e.g. . La1-xCexMnO3,\nLa1-xSnxMnO3) perovskite complex oxide materials. Strong correlation between\nthe spin,lattice, charge and orbital degrees of freedom is a hallmark of these\nclass of materials (popularly known as manganites). Competition and interplay\nof these degrees of freedom lead to a wide range of interesting electronic\nbehavior including half-metallicity, colossal magneto-resistivity, etc.\nAlthough a lot of experimental research has been carried out on the hole doped\nand the electron doped counterparts, the parent system LMO remains less\ninvestigated. This could be attributed to the difficulty in making\nstoichiometric LMO (whether in bulk polycrystalline, single crystals or thin\nfilms). There exists phenomenon like double-exchange (DE) and\nanti-ferromagnetic super-exchange (SE) interactions which leads to\nferromagnetism in LMO thin films. This project work is aimed at the fabrication\nand characterization of thin films of stoichiometric LMO and their structural,\nmagnetic and electrical studies.",
        "positive": "Procedure for 3D atomic resolution reconstructions using atom-counting\n  and a Bayesian genetic algorithm: We introduce a Bayesian genetic algorithm for reconstructing atomic models of\nnanoparticles from a single projection using Z-contrast imaging. The number of\natoms in a projected atomic column obtained from annular dark field scanning\ntransmission electron microscopy (ADF STEM) images serves as an input for the\ninitial three-dimensional (3D) model. The novel algorithm minimizes the energy\nof the structure while utilizing a priori information about the finite\nprecision of the atom-counting results and neighbor-mass relations. The results\nshow excellent prospects for obtaining reliable reconstructions of\nbeam-sensitive nanoparticles during dynamical processes from images acquired\nwith sufficiently low incident electron doses."
    },
    {
        "anchor": "Graphene functionalised by laser ablated V2O5 as highly sensitive NH3\n  sensor: Graphene has been recognized as a promising gas sensing material. The\nresponse of graphene-based sensors can be radically improved by introducing\ndefects in graphene using, e. g., metal or metal oxide nanoparticles. We have\nfunctionalised CVD grown, single layer graphene by applying pulsed laser\ndeposition (PLD) of V2O5 which resulted in a thin V2O5 layer on graphene with\naverage thickness of ~0.6 nm. According to Raman analysis, PLD process also\ninduced defects in graphene. Compared to unmodified graphene, the obtained\nchemiresistive sensor showed considerable improvement of sensing ammonia at\nroom temperature. In addition, also the response time, sensitivity and\nreversibility were essentially enhanced due to graphene functionalisation by\nlaser deposited V2O5. This can be explained by increased surface density of gas\nadsorption sites introduced by high energy atoms in laser ablation plasma and\nformation of nanophase boundaries between deposited V2O5 and graphene.",
        "positive": "Nuclear spin-lattice relaxation studies of Cu$_{2}$O: We report the $^{63}$Cu and $^{65}$Cu nuclear spin-lattice relaxation rate\nmeasurements of cuprous oxide Cu$_2$O in a zero field Cu nuclear quadrupole\nresonance at $T$ = 77$-$325 K. From the detailed isotopic measurements of the\nrelaxation rates, we successfully estimated a finite magnetic relaxation rate\n$^{63}W_M$ and a predominant nuclear quadrupole relaxation rate $^{63}W_Q$.\n$^{63}W_Q$ changed as $T^{2.1}$, while $^{63}W_M$ changed as $T^{1.6}$ or\n$T^{\\beta}\\mathrm{exp}(-\\it\\Delta/T)$ with $\\beta$ = 0.6(3) and $\\it\\Delta$ =\n190(62) K. The nuclear spin scattering process due to a non-degenerate Fermi\ngas was discussed as a possible candidate of the magnetic relaxation."
    },
    {
        "anchor": "Classical Langevin Dynamics for Model Hamiltonians: We propose a scheme for extending the model Hamiltonian method developed\noriginally for studying the equilibrium properties of complex perovskite\nsystems to include Langevin dynamics. The extension is based on Zwanzig's\ntreatment of nonlinear generalized Langevin's equations. The parameters\nentering the equations of motion are to be determined by mapping from\nfirst-principles calculations, as in the original model Hamiltonian method. The\nscheme makes possible, in principle, the study of the dynamics and kinetics of\nstructural transformations inaccessible to the original model Hamiltonian\nmethod. Moreover, we show that the equilibrium properties are governed by an\neffective Hamiltonian which differs from that used in previous work by a term\nwhich captures the coherent part of the previously ignored dynamical\ninteraction with the omitted degrees of freedom. We describe how the additional\ninformation required for the Langevin equations can be obtained by a minor\nextension of the previous mapping.",
        "positive": "Hot phonon decay in supported and suspended exfoliated graphene: Near infrared pump-probe spectroscopy has been used to measure the ultrafast\ndynamics of photoexcited charge carriers in monolayer and multilayer graphene.\nWe observe two decay processes occurring on 100 fs and 2 ps timescales. The\nfirst is attributed to the rapid electron-phonon thermalisation in the system.\nThe second timescale is found to be due to the slow decay of hot phonons. Using\na simple theoretical model we calculate the hot phonon decay rate and show that\nit is significantly faster in monolayer flakes than in multilayer ones. In\ncontrast to recent claims, we show that this enhanced decay rate is not due to\nthe coupling to substrate phonons, since we have also seen the same effect in\nsuspended flakes. Possible intrinsic decay mechanisms that could cause such an\neffect are discussed."
    },
    {
        "anchor": "Magnetotransport in ferromagnetic Fe$_2$Ge semimetallic thin films: Thin films of the ferromagnet Fe$_2$Ge were grown via molecular beam epitaxy,\nand their electrical and magneto-transport properties measured for the first\ntime. X-ray diffraction and vibrating sample magnetometry measurements\nconfirmed the crystalline ferromagnetic Fe$_2$Ge phase. The observed high\ntemperature maximum in the longitudinal resistivity, as well as the observed\nsuppression of electron-magnon scattering at low temperatures, point to the\npresence of strong spin polarization in this material. Measurements of the Hall\nresistivity, $\\rho_{xy}$, show contributions from both the ordinary Hall effect\nand anomalous Hall effect, $\\rho_{xy}^{AH}$, from which we determined the\ncharge carrier concentration and mobility. Measurements also show a small\nnegative magnetoresistance in both the longitudinal and transverse geometries.\nFe$_2$Ge holds promise as a useful spintronic material, especially for its\nsemiconductor compatibility.",
        "positive": "Wafer-Scale Electroactive Nanoporous Silicon: Large and Fully Reversible\n  Electrochemo-Mechanical Actuation in Aqueous Electrolytes: Nanoporosity in silicon results in an interface-dominated mechanics, fluidics\nand photonics that are often superior to the ones of the bulk material.\nHowever, their active control, e.g. as a response to electronic stimuli, is\nchallenging due to the absence of intrinsic piezoelectricity in the base\nmaterial. Here, for large-scale nanoporous silicon cantilevers wetted by\naqueous electrolytes, we show electrosorption-induced mechanical stress\ngeneration of up to 600 kPa that is reversible and adjustable at will by\nelectrical potential variations of approximately 1 V. Laser cantilever bending\nexperiments in combination with in-operando cyclic voltammetry and\nstep-coulombmetry allow us to quantitatively trace this large electro-actuation\nto the concerted action of 100 billions of parallel nanopores per square\ncentimeter cross section and to determine the capacitive charge-stress coupling\nparameter upon ion ad- and desorption as well as the intimately related stress\nactuation dynamics for perchloric and isotonic saline solutions. A comparison\nwith planar silicon surfaces reveals mechanistic insights on the observed\nelectrocapillarity (electrostatic Hellmann-Feynman interactions) with respect\nto the importance of oxide formation and pore-wall roughness on the\nsingle-nanopore scale. The observation of robust electrochemo-mechanical\nactuation in a mainstream semiconductor with wafer-scale, self-organized\nnanoporosity opens up entirely novel opportunities for on-chip integrated\nstress generation and actuorics at exceptionally low operation voltages."
    },
    {
        "anchor": "A dislocation-based explanation of quasi-elastic release in shock-loaded\n  aluminum: A novel explanation of the quasielastic release phenomenon in shock\ncompressed aluminum is presented. A dislocation-based model, taking into\naccount dislocation substructures and evolution, is applied to simulate the\nelastic plastic response of both single crystal and poly crystalline aluminum.\nThe calculated results are in good agreement with experimental results from not\nonly the velocity profiles but also the shear strength and dislocation density,\nwhich demonstrates the accuracy of our simulations. Simulated results indicate\nthat dislocation immobilization during dynamic deformation results in a smooth\nincrease of yield stress, which leads to the quasi-elastic release, while the\ngeneration of dislocations caused by the plastic release wave results in the\nappearance of a transition point between the quasielastic release and the\nplastic release in the profile.",
        "positive": "Once More About the \"Forbidden\" Domain Structure and the Isolated Point\n  in K2Cd2xMn2(1-x)(SO4)3 Langbeinites: The domain structure in K2Cd2xMn2(1-x)(SO4)3 (x=0.5, 0.7 and 0.9) langbeinite\ncrystals is studied with the aid of optical polarization microscopy. It is\nshown that the domain walls in ferro-elastic langbeinites separate\nenantiomorphous orientation states. These orientation states appear in the\nphase with the symmetry 23 in connection with the hypothetic phase transition .\nIn the phase with the symmetry 222, these domain walls are transformed to those\nseparating ferroelastic domains with the opposite signs of enantiomorphism. It\nis revealed that one enantiomorphous domain can only transform to the other via\na thick layer of the parent phase with symmetry. The results for the volume\nthermal expansion are presented. It is shown that the isolated point at the\nx,T-phase diagram of K2Cd2xMn2(1-x)(SO4)3 solid solutions corresponds to the\nconcentration x=0.6."
    },
    {
        "anchor": "Scattering of flexural acoustic phonons at grain boundaries in graphene: We investigate the scattering of long-wavelength flexural phonons against\ngrain boundaries in graphene using molecular dynamics simulations. Three\nsymmetric tilt grain boundaires are considered: one with a misorientation angle\nof $17.9^\\circ$ displaying an out-of-plane buckling 1.5 nm high and 5 nm wide,\none with a misorientation angle of $9.4^\\circ$ and an out-of-plane buckling 0.6\nnm high and 1.7 nm wide, and one with a misorientation angle of $32.2^\\circ$\nand no out-of-plane buckling. At the flat grain boundary, the phonon\ntransmission exceeds 95 % for wavelengths above 1 nm. The buckled boundaries\nhave a substantially lower transmission in this wavelength range, with a\nminimum transmission of 20 % for the $17.9^\\circ$ boundary and 40 % for the\n$9.4^\\circ$ boundary. At the buckled boundaries, coupling between flexural and\nlongitudinal phonon modes is also observed. The results indicate that\nscattering of long-wavelength flexural phonons at grain boundaries in graphene\nis mainly due to out-of-plane buckling. A continuum mechanical model of the\nscattering process has been developed, providing a deeper understanding of the\nscattering process as well as a way to calculate the effect of a grain boundary\non long-wavelength flexural phonons based on the buckling size.",
        "positive": "Microstructural enrichment functions based on stochastic Wang tilings: This paper presents an approach to constructing microstructural enrichment\nfunctions to local fields in non-periodic heterogeneous materials with\napplications in Partition of Unity and Hybrid Finite Element schemes. It is\nbased on a concept of aperiodic tilings by the Wang tiles, designed to produce\nmicrostructures morphologically similar to original media and enrichment\nfunctions that satisfy the underlying governing equations. An appealing feature\nof this approach is that the enrichment functions are defined only on a small\nset of square tiles and extended to larger domains by an inexpensive stochastic\ntiling algorithm in a non-periodic manner. Feasibility of the proposed\nmethodology is demonstrated on constructions of stress enrichment functions for\ntwo-dimensional mono-disperse particulate media."
    },
    {
        "anchor": "Crystal Structure and Magnetic Properties of the New Zn1.5Co1.5B7O13Br\n  Boracite: New Zn1.5Co1.5B7O13Br boracite crystals were grown by chemical transport\nreactions in quartz ampoules, at a temperature of 1173 K. The crystal structure\nwas characterized by X-ray diffraction. The crystals present an orthorhombic\nstructure with space group Pca21, (No. 29). The determined cell parameters\nwere: a = 8.5705(3){\\AA}, b = 8.5629(3) {\\AA}, and c = 12.1198(4){\\AA}, and\ncell volume, V = 889.45(5) {\\AA}3 with Z = 4. Magnetic properties in single\ncrystals of the new boracite, were determined. The Susceptibility-Temperature\n(X -T) behavior at different magnetic intensities was studied. The inverse of\nthe magnetic susceptibility X-1(T) shows a Curie-Weiss characteristic with spin\ns = 3/2 and a small orbital contribution, l. At low temperatures, below 10 K,\nX(T) shows irreversibility that is strongly dependent on the applied magnetic\nfield. This boracite is ferrimagnetic up to a maximum temperature of about 16\nK, as shows the coercive field. The reduction of the irreversibility by the\ninfluence of the magnetic field, may be related to a metamagnetic phase\ntransition.",
        "positive": "Hillock formation of Pt thin films on Yttria stabilized Zirconia single\n  crystals: The stability of a metal thin films on a dielectric substrate is conditioned\nby the magnitude of the interactive forces at the interface. In the case of a\nnon-reactive interface and weak adhesion, the minimization of free surface\nenergy gives rise to an instability of the thin film. In order to study these\neffects, Pt thin films with a thickness of 50 nm were deposited via ion-beam\nsputtering on yttria stabilized zirconia single crystals. All Pt films were\nsubjected to heat treatments up to 973 K for 2 h. The morphological evolution\nof Pt thin films has been investigated by means of scanning electron microscopy\n(SEM), atomic force microscopy (AFM) and standard image analysis techniques.\nThree main observations have been made: i) the deposition method has a direct\nimpact on the morphological evolution of the film during annealing. Instead of\nhole formation, that is typically observed as response to a thermal treatment,\nanisotropic pyramidal shaped hillocks are formed on top of the film. ii) It is\nshown by comparing the hillocks' aspect ratio with finite element method (FEM)\nsimulations that the hillock formation can be assigned to a stress relaxation\nprocess inside the thin film. iii) By measuring the equilibrium shapes and the\nshape fluctuations of the formed Pt hillocks the anisotropy of the step free\nenergy and its stiffness have been derived in addition to the anisotropic kink\nenergy of the hillock's edges."
    },
    {
        "anchor": "Non-thermal laser induced precession of magnetization in ferromagnetic\n  semiconductor (Ga,Mn)As: Non-thermal laser induced spin excitations, recently discovered in\nconventional oxide and metal ferromagnets, open unprecedented opportunities for\nresearch and applications of ultrafast optical manipulation of magnetic\nsystems. Ferromagnetic semiconductors, and (Ga,Mn)As in particular, should\nrepresent ideal systems for exploring this new field. Remarkably, the presence\nof non-thermal effects has remained one of the outstanding unresolved problems\nin the research of ferromagnetic semiconductors to date. Here we demonstrate\nthat coherent magnetization dynamics can be excited in (Ga,Mn)As non-thermally\nby a transfer of angular momentum from circularly polarized femtosecond laser\npulses and by a combination of non-thermal and thermal effects due to a\ntransfer of energy from laser pulses. The thermal effects can be completely\nsuppressed in piezo-electrically controlled samples. Our work is based on\npump-and-probe measurements in a large set of (Ga,Mn)As epilayers and on\nsystematic analysis of circular and linear magneto-optical coefficients. We\nprovide microscopic theoretical interpretation of the experimental results.",
        "positive": "Ionic liquid gating induced self-intercalation of transition metal\n  chalcogenides: Ionic liquids provide versatile pathways for controlling the structures and\nproperties of quantum materials. Previous studies have reported electrostatic\ngating of nanometre-thick flakes leading to emergent superconductivity,\ninsertion or extraction of protons and oxygen ions in perovskite oxide films\nenabling the control of different phases and material properties, and\nintercalation of large-sized organic cations into layered crystals giving\naccess to tailored superconductivity. Here, we report an ionic-liquid gating\nmethod to form three-dimensional transition metal monochalcogenides (TMMCs) by\ndriving the metals dissolved from layered transition metal dichalcogenides\n(TMDCs) into the van der Waals gap. We demonstrate the successful\nself-intercalation of PdTe$_2$ and NiTe$_2$, turning them into high-quality\nPdTe and NiTe single crystals, respectively. Moreover, the monochalcogenides\nexhibit distinctive properties from dichalcogenides. For instance, the\nself-intercalation of PdTe$_2$ leads to the emergence of superconductivity in\nPdTe. Our work provides a synthesis pathway for TMMCs by means of ionic liquid\ngating driven self-intercalation."
    },
    {
        "anchor": "Role of interface morphology on the martensitic transformation in pure\n  Fe: Using classical molecular dynamics simulations, we study austenite to ferrite\nphase transformation in iron, focusing on the role of interface morphology. We\ncompare two different morphologies; a \\textit{flat} interface in which the two\nphases are joined according to Nishiyama-Wasserman orientation relationship vs.\na \\textit{ledged} one, having steps similar to the vicinal surface. We identify\nthe atomic displacements along a misfit dislocation network at the interface\nleading to the phase transformation. In case of \\textit{ledged} interface,\nstacking faults are nucleated at the steps, which hinder the interface motion,\nleading to a lower mobility of the inter-phase boundary, than that of flat\ninterface. Interestingly, we also find the temperature dependence of the\ninterface mobility to show opposite trends in case of \\textit{flat} vs.\n\\textit{ledged} boundary. We believe that our study is going to present a\nunified and comprehensive view of martensitic transformation in iron with\ndifferent interface morphology, which is lacking at present, as \\textit{flat}\nand \\textit{ledged} interfaces are treated separately in the existing\nliterature.",
        "positive": "Crystallographic features of the approximant H (Mn$_7$Si$_2$V) phase in\n  the Mn-Si-V alloy system: The intermetallic compound H (Mn$_7$Si$_2$V) phase in the Mn-Si-V alloy\nsystem can be regarded as an approximant phase of the dodecagonal quasicrystal\nas one of the two-dimensional quasicrystals. To understand the features of the\napproximant H phase, in this study, the crystallographic features of both the H\nphase and the (\\sigma $\\, \\rightarrow$ H) reaction in Mn-Si-V alloy samples\nwere investigated, mainly by transmission electron microscopy. It was found\nthat, in the H phase, there were characteristic structural disorders with\nrespect to an array of a dodecagonal structural unit consisting of 19\ndodecagonal atomic columns. Concretely, penetrated structural units consisting\nof two dodecagonal structural units were presumed to be typical of such\ndisorders. An interesting feature of the (\\sigma $\\, \\rightarrow$ H) reaction\nwas that regions with a rectangular arrangement of penetrated structural units\n(RAPU) first appeared in the \\sigma $\\,$ matrix as the initial state, and H\nregions were then nucleated in contact with RAPU regions. The subsequent\nconversion of RAPU regions into H regions eventually resulted in the formation\nof the approximant H state as the final state. Furthermore, atomic positions in\nboth the H structure and the dodecagonal quasicrystal were examined using a\nsimple plane-wave model with twelve plane waves."
    },
    {
        "anchor": "Observation of spin-momentum locked surface states in amorphous\n  Bi$_{2}$Se$_{3}$: Crystalline symmetries have played a central role in the identification of\ntopological materials. The use of symmetry indicators and band representations\nhave enabled a classification scheme for crystalline topological materials,\nleading to large scale topological materials discovery. In this work we address\nwhether amorphous topological materials, which lie beyond this classification\ndue to the lack of long-range structural order, exist in the solid state. We\nstudy amorphous Bi$_2$Se$_3$ thin films, which show a metallic behavior and an\nincreased bulk resistance. The observed low field magnetoresistance due to weak\nantilocalization demonstrates a significant number of two dimensional surface\nconduction channels. Our angle-resolved photoemission spectroscopy data is\nconsistent with a dispersive two-dimensional surface state that crosses the\nbulk gap. Spin resolved photoemission spectroscopy shows this state has an\nanti-symmetric spin texture resembling that of the surface state of crystalline\nBi$_2$Se$_3$. These experimental results are consistent with theoretical\nphotoemission spectra obtained with an amorphous tight-binding model that\nutilizes a realistic amorphous structure. This discovery of amorphous materials\nwith topological properties uncovers an overlooked subset of topological matter\noutside the current classification scheme, enabling a new route to discover\nmaterials that can enhance the development of scalable topological devices.",
        "positive": "Static disorder and local structure in zinc(II) isonicotinate, a\n  quartzlike metal-organic framework: Using a combination of Rietveld and RMC refinement of neutron total\nscattering data, we find that the 10 K structure of zinc(II) isonicotinate\nshows strong evidence of static disorder. This disorder takes the form of\ntransverse displacements of the isonicotinate ligand and results in elongated\natomic displacement parameters and dampened oscillations of the experimental\nG(r). We analyse the RMC configurations using an approach derived from\ngeometric algebra. Complications regarding the inclusion of hydrogenous guest\nmolecules within the pore structure are discussed. This study highlights the\nway in which structural flexibility can give rise to multiple low-energy ground\nstates in MOF-type materials."
    },
    {
        "anchor": "Deformation and tribology of multi-walled hollow nanoparticles: Multi-walled hollow nanoparticles made from tungsten disulphide (WS$_2$) show\nexceptional tribological performance as additives to liquid lubricants due to\neffective transfer of low shear strength material onto the sliding surfaces.\nUsing a scaling approach based on continuum elasticity theory for shells and\npairwise summation of van der Waals interactions, we show that van der Waals\ninteractions cause strong adhesion to the substrate which favors release of\ndelaminated layers onto the surfaces. For large and thin nanoparticles, van der\nWaals adhesion can cause considerable deformation and subsequent delamination.\nFor the thick WS$_2$ nanoparticles, deformation due to van der Waals\ninteractions remains small and the main mechanism for delamination is pressure\nwhich in fact leads to collapse beyond a critical value. We also discuss the\neffect of shear flow on deformation and rolling on the substrate.",
        "positive": "Ferromagnetic Nano-Structures in Valenta Model: The ferromagnetic nano-structures are recently of great interest for modern\ninvestigations. A comparison of the experimental data and theoretical results\nshows that the use of the standard molecular field approximation is\ninsufficient for the description of nano-structure properties. Therefore, we\nuse the effective field approach in order to show the usefulness of the Valenta\nmodel generalized in this way. The agreement between experiment and theory is\nthen excellent. The magnetization profiles and the calculated Curie\ntemperatures are presented for the systems consisting of Ni and Co layers with\ndifferent configuration of the surfaces and interfaces including terraces and\nwires. We have shown that the position in the system as well as the kind of\nneighbouring layers and their mutual interactions can determine the shape of\nmagnetization profiles. The use of the Valenta model allows us to present all\ndependences in the layer resolved mode."
    },
    {
        "anchor": "Anomalous Magnetic Properties in Ni50Mn35In15: We present here a comprehensive investigation of the magnetic ordering in\nNi50Mn35In15 composition. A concomitant first order martensitic transition and\nthe magnetic ordering occurring in this off-stoichiometric Heusler compound at\nroom temperature signifies the multifunctional character of this magnetic shape\nmemory alloy. Unusual features are observed in the dependence of the\nmagnetization on temperature that can be ascribed to a frustrated magnetic\norder. It is compelling to ascribe these features to the cluster type\ndescription that may arise due to inhomogeneity in the distribution of magnetic\natoms. However, evidences are presented from our ac susceptibility, electrical\nresistivity and dc magnetization studies that there exists a competing\nferromagnetic and antiferromagnetic order within crystal structure of this\nsystem. We show that excess Mn atoms that substitute the In atoms have a\ncrucial bearing on the magnetic order of this compound. These excess Mn atoms\nare antiferromagnetically aligned to the other Mn, which explains the peculiar\ndependence of magnetization on temperature.",
        "positive": "The melting curve of MgO from first principles simulations: First principles calculations based on density functional theory, both with\nthe local density approximation (LDA) and with generalised gradient corrections\n(GGA), and the projector augmented wave method, have been used to simulate\nsolid and liquid MgO in direct coexistence in the range of pressure $0\\le p \\le\n135$ GPa. The calculated LDA zero pressure melting temperature is $ T_m^{\\rm\nLDA} = 3110 \\pm 50 $ K, in good agreement with the experimental data. The\ncalculated GGA zero pressure melting temperature $ T_m^{\\rm GGA} = 2575 \\pm 100\n$ K is significantly lower than the LDA one, but the difference between the GGA\nand the LDA melting curves is greatly reduced at high pressure. The LDA\ncalculated zero pressure melting slope is $dT/dp \\sim 100$ K/GPa, which is more\nthan three times higher than the currently available experimental one ((Zerr\nand Boehler, Nature {\\bf 371}, 506 (1994)). As the pressure is increased, the\nmelting curve deviates significantly from the experimental one. At the core\nmantle boundary pressure of 135 GPa MgO melts at $T_m = 8140 \\pm 150$ K."
    },
    {
        "anchor": "Sensing Strain-induced Symmetry Breaking by Reflectance Anisotropy\n  Spectroscopy: Intentional breaking of the lattice symmetry in solids is a key concept to\nalter the properties of materials by modifying their electronic band structure.\nHowever, the correlation of strain-induced effects and breaking of the lattice\nsymmetry is often indirect, resorting to vibrational spectroscopic techniques\nsuch as Raman scattering. Here, we demonstrate that reflectance anisotropy\nspectroscopy (RAS), which directly depends on the complex dielectric function,\nenables the direct observation of electronic band structure modulation.\nStudying the strain-induced symmetry breaking in copper, we show how uniaxial\nstrain lifts the degeneracy of states in the proximity of the both L and X\nsymmetry points, thus altering the matrix element for interband optical\ntransitions, directly observable in RAS. We corroborate our experimental\nresults by analysing the strain-induced changes in the electronic structure\nbased on ab-initio density functional theory calculations. The versatility to\nstudy breaking of the lattice symmetry by simple reflectance measurements opens\nup the possibility to gain a direct insight on the band-structure of other\nstrain-engineered materials, such as graphene and two-dimensional (2D)\ntransition metal dichalcogenides (TMDCs).",
        "positive": "Fermi level position, Coulomb gap, and Dresselhaus splitting in\n  (Ga,Mn)As: Carrier-induced nature of ferromagnetism in a ferromagnetic semiconductor,\n(Ga,Mn)As, offers a great opportunity to observe novel spin-related phenomena\nas well as to demonstrate new functionalities of spintronic devices. Here, we\nreport on low-temperature angle-resolved photoemission studies of the valence\nband in this model compound. By a direct determination of the distance of the\nsplit-off band to the Fermi energy EF, we conclude that EF is located within\nthe heavy/light hole band. However, the bands are strongly perturbed by\ndisorder and disorder-induced carrier correlations that lead to the Coulomb gap\nat EF, which we resolve experimentally in a series of samples, and show that\nits depth and width enlarge when the Curie temperature decreases. Furthermore,\nwe have detected surprising linear magnetic dichroism in photoemission spectra\nof the split-off band. By a quantitative theoretical analysis we demonstrate\nthat it arises from the Dresselhaus-type spin-orbit term in zinc-blende\ncrystals. The spectroscopic access to the magnitude of such asymmetric part of\nspin-orbit coupling is worthwhile, as they account for spin-orbit torque in\nspintronic devices of ferromagnets without inversion symmetry."
    },
    {
        "anchor": "Optical reflectivity and magnetoelectric effects on resonant plasmon\n  modes in composite metal-multiferroic systems: The r\\^{o}le of the magnetoelectric effect upon optical reflectivity is\nstudied by adapting an electrodynamic-based model for a system composed by a 2D\nmetallic film in contact with an extended multiferroic material exhibiting weak\nferromagnetism. The well-known \\emph{Nakayama's} boundary condition is\nreformulated by taking into account the magnetoelectric coupling as well as an\nexternally applied magnetic field $\\mathbf{B}$ in an arbitrary direction. It is\nfound that the reflectance shows strong fluctuations for incident radiation\nclose to the characteristic antiferromagnetic resonance frequency associated\nwith the multiferroic material in the THz regime. These results were verified\nfor a 10 nm metallic foil by using a finite element method (FEM) and the\nRouard's approach, for a wide range of wavelengths (0.1 - 5 mm), showing good\nagreement with respect to Nakayama's outcome, for the particular material\nBaMnF$_4$.",
        "positive": "Acoustic Holographic Rendering with Two-dimensional Metamaterial-based\n  Passive Phased Array: Acoustic holographic rendering in complete analogy with optical holography\nare useful for various applications, ranging from multi-focal lensing,\nmultiplexed sensing and synthesizing three-dimensional complex sound fields.\nConventional approaches rely on a large number of active transducers and phase\nshifting circuits. In this paper we show that by using passive metamaterials as\nsubwavelength pixels, holographic rendering can be achieved without cumbersome\ncircuitry and with only a single transducer, thus significantly reducing system\ncomplexity. Such metamaterial-based holograms can serve as versatile platforms\nfor various advanced acoustic wave manipulation and signal modulation, leading\nto new possibilities in acoustic sensing, energy deposition and medical\ndiagnostic imaging."
    },
    {
        "anchor": "Lowering of surface melting temperature in atomic clusters with a nearly\n  closed shell structure: We investigate the interplay of particle number, N, and structural properties\nof selected clusters with N=12 up to N=562 by employing Gupta potentials\nparameterized for Aluminum and extensive Monte-Carlo simulations. Our analysis\nfocuses on closed shell structures with extra atoms. The latter can put the\ncluster under a significant stress and we argue that typically such a strained\nsystem exhibits a reduced energy barrier for (surface) diffusion of cluster\natoms. Consequently, also its surface melting temperature, T_S, is reduced, so\nthat T_S separates from and actually falls well below the bulk value. The\nproposed mechanism may be responsible for the suppression of the surface\nmelting temperature observed in a recent experiments.",
        "positive": "Berry-phase theory of proper piezoelectric response: Recent theoretical advances have established that the electric polarization\nin an insulating crystal can be viewed as a multivalued quantity that is\ndetermined by certain Berry phases associated with the occupied Bloch bands.\nThe application of this approach to the computation of piezoelectric\ncoefficients is not entirely straightforward, since a naive determination of\nthe (``improper'') piezoelectric coefficients from finite differences of the\npolarization at nearby strain states leads to a dependence upon the choice of\n``branch'' of the polarization. The purpose of the present paper is to clarify\nthat if one calculates instead the ``proper'' piezoelectric response, the\nbranch dependence is eliminated. From this analysis, a simplified recipe for\nthe direct finite-difference computation of the proper piezoelectric\ncoefficients emerges naturally."
    },
    {
        "anchor": "Electron-electron interaction effects on optical excitations in\n  semiconducting single-walled carbon nanotubes: We report correlated-electron calculations of optically excited states in ten\nsemiconducting single-walled carbon nanotubes with a wide range of diameters.\nOptical excitation occurs to excitons whose binding energies decrease with the\nincreasing nanotube diameter, and are smaller than the binding energy of an\nisolated strand of poly-(paraphenylene vinylene). The ratio of the energy of\nthe second optical exciton polarized along the nanotube axis to that of the\nlowest exciton is smaller than the value predicted within single-particle\ntheory. The experimentally observed weak photoluminescence is an intrinsic\nfeature of semiconducting nanotubes, and is consequence of dipole-forbidden\nexcitons occurring below the optical exciton.",
        "positive": "Anharmonic stabilization and band gap renormalization in the perovskite\n  CsSnI$_3$: Amongst the X(Sn,Pb)Y$_3$ perovskites currently under scrutiny for their\nphotovoltaic applications, the cubic B-$\\alpha$ phase of CsSnI$_3$ is arguably\nthe best characterized experimentally. Yet, according to the standard harmonic\ntheory of phonons, this deceptively simple phase should not exist at all due to\nrotational instabilities of the SnI$_6$ octahedra. Here, employing\nself-consistent phonon theory we show that these soft modes are stabilized at\nexperimental conditions through anharmonic phonon-phonon interactions between\nthe Cs ions and their iodine cages. We further calculate the renormalization of\nthe electronic energies due to vibrations and find an unusual opening of the\nband gap, estimated as 0.24 and 0.11 eV at 500 and 300 K, which we attribute to\nthe stretching of Sn-I bonds. Our work demonstrates the important role of\ntemperature in accurately describing these materials."
    },
    {
        "anchor": "Electron Transport in Silicon Nanowires: The Role of Acoustic Phonon\n  Confinement and Surface Roughness Scattering: We investigate the effects of electron and acoustic-phonon confinement on the\nlow-field electron mobility of thin square silicon nanowires (SiNWs) that are\nsurrounded by SiO$_2$ and gated. We employ a self-consistent\nPoisson-Schr\\\"{o}dinger-Monte Carlo solver that accounts for scattering due to\nacoustic phonons (confined and bulk), intervalley phonons, and the Si/SiO$_2$\nsurface roughness. The wires considered have cross sections between 3 $\\times$\n3 nm$^2$ and 8 $\\times$ 8 nm$^2$. For larger wires, as expected, the dependence\nof the mobility on the transverse field from the gate is pronounced. At low\ntransverse fields, where phonon scattering dominates, scattering from confined\nacoustic phonons results in about a 10% decrease of the mobility with respect\nto the bulk phonon approximation. As the wire cross-section decreases, the\nelectron mobility drops because the detrimental increase in both\nelectron--acoustic phonon and electron--surface roughness scattering rates\novershadows the beneficial volume inversion and subband modulation. For wires\nthinner than 5 $\\times$ 5 nm$^2$, surface roughness scattering dominates\nregardless of the transverse field applied and leads to a monotonic decrease of\nthe electron mobility with decreasing SiNWs cross section.",
        "positive": "Laws of crack motion and phase-field models of fracture: Recently proposed phase-field models offer self-consistent descriptions of\nbrittle fracture. Here, we analyze these theories in the quasistatic regime of\ncrack propagation. We show how to derive the laws of crack motion either by\nusing solvability conditions in a perturbative treatment for slight departure\nfrom the Griffith threshold, or by generalizing the Eshelby tensor to\nphase-field models. The analysis provides a simple physical interpretation of\nthe second component of the classic Eshelby integral in the limit of vanishing\ncrack propagation velocity: it gives the elastic torque on the crack tip that\nis needed to balance the Herring torque arising from the anisotropic interface\nenergy. This force balance condition reduces in this limit to the principle of\nlocal symmetry in isotropic media and to the principle of maximum energy\nrelease rate for smooth curvilinear cracks in anisotropic media. It can also be\ninterpreted physically in this limit based on energetic considerations in the\ntraditional framework of continuum fracture mechanics, in support of its\ngeneral validity for real systems beyond the scope of phase-field models.\nAnalytical predictions of crack paths in anisotropic media are validated by\nnumerical simulations. Simulations also show that these predictions hold even\nif the phase-field dynamics is modified to make the failure process\nirreversible. In addition, the role of dissipative forces on the process zone\nscale as well as the extension of the results to motion of planar cracks under\npure antiplane shear are discussed."
    },
    {
        "anchor": "Point defects and dopants of boron arsenide from first-principles\n  calculations: donor compensation and doping asymmetry: We apply hybrid density functional theory calculations to identify the\nformation energies and thermodynamic charge transition levels of native point\ndefects, common impurities, and shallow dopants in BAs. We find that\nboron-related defects such as V_B, B_As, B_i-V_B complexes, and antisite pairs\nare the dominant intrinsic defects. Native BAs is expected to exhibit p-type\nconduction due to the acceptor-type characteristics of V_B and B_As. Among the\ncommon impurities we explored, we found that C substitutional defects and H\ninterstitials have relatively low formation energies and are likely to\ncontribute free holes. Interstitial hydrogen is surprisingly also found to be\nstable in the neutral charge state. Be_B, Si_As and Ge_As are predicted to be\nexcellent shallow acceptors with low ionization energy (< 0.03 eV) and\nnegligible compensation by other point defects considered here. On the other\nhand, donors such as Se_As, Te_As, Si_B, and Ge_B have a relatively large\nionization energy (~0.15 eV) and are likely to be passivated by native defects\nsuch as B_As and V_B, as well as C_As, H_i, and H_B. The hole and electron\ndoping asymmetry originates from the heavy effective mass of the conduction\nband due to its boron orbital character, as well as from boron-related\nintrinsic defects that compensate donors.",
        "positive": "Revisiting the Thomas-Fermi Potential for Three-Dimensional Condensed\n  Matter Systems: We proposed a formally exact, probabilistic method to assess the validity of\nthe Thomas-Fermi potential for three-dimensional condensed matter systems where\nelectron dynamics is constrained to the Fermi surface. Our method, which relies\non accurate solutions of the radial Schr\\\"{o}dinger equation, yields the\nprobability density function for momentum transfer. This allows for the\ncomputation of its expectation values, which can be compared with unity to\nconfirm the validity of the Thomas-Fermi approximation. We applied this method\nto three {\\it n}-type direct-gap III-V model semiconductors (GaAs, InAs, InSb)\nand found that the Thomas-Fermi approximation is certainly valid at high\nelectron densities. In these cases, the probability density function exhibits\nthe same profile, irrespective of the material under scrutiny. Furthermore, we\nshow that this approximation can lead to serious errors in the computation of\nobservables when applied to GaAs at zero temperature for most electron\ndensities under scrutiny."
    },
    {
        "anchor": "Frenkel biexcitons in hybrid HJ photophysical aggregates: Frenkel excitons, the primary photoexcitations in organic semiconductors that\nare unequivocally responsible for the optical properties of this materials\nclass, are predicted to form \\emph{bound} exciton pairs, i.e., biexcitons.\nThese are key intermediates, ubiquitous in many relevant photophysical\nprocesses; for example, they determine the exciton bimolecular annihilation\ndynamics in such systems. Deciphering the details of biexciton correlations is,\nthus, of utmost importance to understand the optical processes in these\nsemiconductors. To date, however, due to their spectral ambiguity, there has\nbeen only scant direct evidence of bound biexcitons, limiting the insights that\ncan be gained. Moreover, a quantum-mechanical basis describing biexciton\ncorrelation/stability has so far been lacking. By employing nonlinear coherent\nspectroscopy, we identify here bound biexcitons in a model polymeric\nsemiconductor. We find, unexpectedly, that excitons with \\emph{interchain}\nvibronic dispersion reveal \\emph{intrachain} biexciton correlations and vice\nversa. Moreover, using a Frenkel exciton model, we can relate the biexciton\nbinding energy to molecular parameters quantified by quantum chemistry,\nincluding the magnitude and sign of the exciton-exciton interaction the\ninter-site hopping energies. Therefore, our work promises a window towards\ngeneral insights into the many-body electronic structure in polymeric\nsemiconductors and beyond; e.g., other excitonic systems such as organic\nsemiconductor crystals, molecular aggregates, photosynthetic light-harvesting\ncomplexes, or DNA.",
        "positive": "The origin of the dead-layer at the La0.67Sr0.33MnO3/SrTiO3 interface\n  and dead-layer reduction via interfacial engineering: Transition metal oxide hetero-structure has great potential for\nmultifunctional devices. However, the degraded physical properties at\ninterface, known as dead-layer behavior, present a main obstacle for device\napplications. Here we present the systematic study of the dead-layer behavior\nin La0.67Sr0.33MnO3 thin film grown on SrTiO3 substrate with ozone assisted\nmolecular beam epitaxy. We found that the evolution of electric and magnetic\nproperties as a function of thickness shows a remarkable resemblance to the\nphase diagram as a function of doping for bulk materials, providing compelling\nevidences of the hole depletion in near interface layers that causes\ndead-layer. Detailed electronic and surface structure studies indicate that the\nhole depletion is due to the intrinsic oxygen vacancy formation. Furthermore,\nwe show that oxygen vacancies are partly caused by interfacial electric dipolar\nfield, and thus by doping-engineering at the single-atomic-layer level, we\ndemonstrate the dead-layer reduction in films with higher interfacial hole\nconcentration."
    },
    {
        "anchor": "Atom Probe Tomography Spatial Reconstruction: Status and Directions: In this review we present an overview of the current atom probe tomography\nspatial data reconstruction paradigm, and explore some of potential routes to\nimprove the current methodology in order to yield a more accurate\nrepresentation of nanoscale microstructure. Many of these potential improvement\nmethods are directly tied to extensive application of advanced numerical\nmethods, which are also very briefly reviewed. We have described effects\nresulting from the application of the standard model and then introduced\nseveral potential improvements, first in the far field, and, second, in the\nnear field. The issues encountered in both cases are quite different but\nultimately they combine to determine the spatial resolution of the technique.",
        "positive": "Raman Spectroscopy of Graphene Edges: Graphene edges are of particular interest, since their chirality determines\nthe electronic properties. Here we present a detailed Raman investigation of\ngraphene flakes with well defined edges oriented at different crystallographic\ndirections. The position, width and intensity of G and D peaks at the edges are\nstudied as a function of the incident light polarization. The D-band is\nstrongest for light polarized parallel to the edge and minimum for\nperpendicular orientation. Raman mapping shows that the D peak is localized in\nproximity of the edge. The D to G ratio does not always show a significant\ndependence on edge orientation. Thus, even though edges can appear\nmacroscopically smooth and oriented at well defined angles, they are not\nnecessarily microscopically ordered."
    },
    {
        "anchor": "Bauschinger Effect in Thin Metal Films: Discrete Dislocation Dynamics\n  Study: The effects of dislocation climb on plastic deformation during loading and\nunloading are studied using a two-dimensional discrete dislocation dynamics\nmodel. Simulations are performed for polycrystalline thin films passivated on\nboth surfaces. Dislocation climb lowers the overall level of the stress inside\nthin films and reduces the work hardening rate. Climb decreases the density of\ndislocations in pile-ups and reduces back stresses. These factors result in a\nsmaller Bauschinger effect on unloading compared to simulations without climb.\nAs dislocations continue to climb at the onset of unloading and the dislocation\ndensity continues to increase, the initial unloading slope increases with\ndecreasing unloading rate. Because climb disperses dislocations, fewer\ndislocations are annihilated during unloading, leading to a higher dislocation\ndensity at the end of the unloading step.",
        "positive": "Collapse and control of the MnAu$_{2}$ spin-spiral state through\n  pressure and doping: MnAu$_{2}$ is a spin-spiral material with in-plane ferromagnetic Mn layers\nthat form a screw-type pattern around a tetragonal $c$ axis. The spiral angle\n$\\theta$ was shown using neutron diffraction experiments to decrease with\npressure, and in later studies it was found to suffer a collapse to a\nferromagnetic state above a critical pressure, although the two separate\nexperiments did not agree on whether this phase transition is first or second\norder. To resolve this contradiction, we use density functional theory\ncalculations to investigate the spiral state as a function of pressure, charge\ndoping, and also electronic correlations via a Hubbard-like $U$. We fit the\nresults to the one-dimensional $J_{1} - J_{2} - J_{3} - J_{4}$ Heisenberg\nmodel, which predicts either a first- or second-order spiral-to-ferromagnetic\nphase transition for different regions of parameter space. At ambient pressure,\nMnAu$_{2}$ sits close in parameter space to a dividing line separating first-\nand second-order transitions, and a combination of pressure and electron doping\nshifts the system from the first-order region into the second-order region. Our\nfindings demonstrate that the contradiction in pressure experiments regarding\nthe kind of phase transition are likely due to variations in sample quality.\nOur results also suggest that MnAu$_{2}$ is amenable to engineering via\nchemical doping and to controlling $\\theta$ using pressure and gate voltages,\nwhich holds potential for integration in spintronic devices."
    },
    {
        "anchor": "Empirical Exploration of Deformation Mechanisms in Deep Rock Exposed to\n  Multiple Stresses: To avoid the impact of inherent natural imperfections on experimental\noutcomes during testing, a recently designed genuine triaxial apparatus has\nenabled the replication of conditions where the three principal stresses\nexhibit varying magnitudes. This setup facilitates the examination of fracture\nbehaviors in materials similar to the 4-series under genuine triaxial stress\nstates. The experimental findings revealed that the maximum strength\nexperiences significant influence from the minimum principal stress and the\nintermediate principal stress in genuine triaxial stress conditions.\nSpecifically, for a fixed minimum principal stress ({\\sigma}3), there is a\nprogressive reduction in peak strain as the intermediate principal stress\n({\\sigma}2) increases. Moreover, as the minimum principal stress ({\\sigma}3)\nrises, the magnitude of peak strain diminishes. The Young's modulus of the\nspecimens exhibits an exponential increase with the augmentation of confining\npressure, and it demonstrates a linear growth pattern as the intermediate\nprincipal stress increases. Additionally, the cohesion force is observed to\nrise while the internal friction angle decreases with the elevation of the\nintermediate principal stress. The failure modes of the specimens in genuine\ntriaxial stress conditions can be categorized into three types, all of which\nexhibit a specific angle between the fracture surface and {\\sigma}3, ranging\nfrom 50 to 62 degrees. Furthermore, a comparison between the computed range and\nthe actual measurement range of the fracture angle highlights several\nlimitations in the relationship between the fracture angle ({\\theta}) and the\ninternal friction angle ({\\phi}) within the Coulomb criterion, particularly in\nrocks containing complex fracture systems.",
        "positive": "A Group-theoretical Approach to Enumerating Magnetoelectric and\n  Multiferroic Couplings in Perovskites: We use a group theoretical approach to enumerate the possible couplings\nbetween magnetism and ferroelectric polarisation in the parent $Pm\\bar{3}m$\nperovskite structure. We show that third order magnetoelectric coupling terms\nmust always involve magnetic ordering at the A and B-site which either\ntransforms both as R-point or both as X-point time odd irreducible\nrepresentations (irreps). For fourth order couplings we demonstrate that this\ncriterion may be relaxed allowing couplings involving irreps at X, M and\nR-points which collectively conserve crystal momentum, producing a\nmagnetoelectric effect arising from only B-site magnetic order. In this case,\nexactly two of the three irreps entering the order parameter must be time-odd\nirreps and either one or all must be even with respect to inversion symmetry.\nWe are able to show that the time-even irreps in this triad must transform as\none of: X$_{1}^{-}$, M$_{3,5}^{-}$ and R$_{5}^{+}$, corresponding to A-site\ncation order, A-site anti-polar displacements or anion rock-salt ordering. This\ngreatly reduces the search-space for (type-II multiferroic) perovskites. We use\nsimilar arguments to demonstrate how weak ferromagnetism may be engineered, and\nwe propose a variety of schemes for coupling this to ferroelectric\npolarisation. We illustrate our approach with DFT calculations on\nmagnetoelectric couplings, and by considering the literature we suggest which\navenues of research are likely to be most promising in the design of novel\nmagnetoelectric materials."
    },
    {
        "anchor": "Single-crystal graphene on Ir(110): A single-crystal sheet of graphene is synthesized on the low-symmetry\nsubstrate Ir(110) by thermal decomposition of C$_2$H$_4$ at 1500 K. Using\nscanning tunneling microscopy, low-energy electron diffraction, angle-resolved\nphotoemission spectroscopy, and ab initio density functional theory the\nstructure and electronic properties of the adsorbed graphene sheet and its\nmoir\\'e with the substrate are uncovered. The adsorbed graphene layer forms a\nwave pattern of nm wave length with a corresponding modulation of its\nelectronic properties. This wave pattern is demonstrated to enable the\ntemplated adsorption of aromatic molecules and the uniaxial growth of\norganometallic wires. Not limited to this, graphene on Ir(110) is also a\nversatile substrate for 2D-layer growth and makes it possible to grow epitaxial\nlayers on ureconstructed Ir(110).",
        "positive": "Temperature dependence of the threshold magnetic field for nucleation\n  and domain wall propagation in an inhomogeneous structure with grain boundary: In order to study the dependence of the coercive force of sintered magnets on\ntemperature, nucleation and domain wall propagation at the grain boundary are\nstudied as rate-determining processes of the magnetization reversal phenomena\nin magnets consisting of bulk hard magnetic grains contacting via grain\nboundaries of a soft magnetic material. These systems have been studied\nanalytically for a continuum model at zero temperature (A. Sakuma, et al. J.\nMag. Mag. Mat. {\\bf 84} 52 (1990)). In the present study, the temperature\ndependence is studied by making use of the stochastic Landau-Lifshitz-Gilbert\nequation at finite temperatures. In particular, the threshold fields for\nnucleation and domain wall propagation are obtained as functions of ratios of\nmagnetic interactions and anisotropies of the soft and hard magnets for various\ntemperatures. It was found that the threshold field for domain wall propagation\nis robust against thermal fluctuations, while that for nucleation is fragile.\nThe microscopic mechanisms of the observed temperature dependence are\ndiscussed."
    },
    {
        "anchor": "Magnetic glassy state at low spin state of Co3+ in EuBaCo2O5+\u03b4\n  (\u03b4 = 0.47) cobaltite: The magnetic glassy state is a fascinating phenomenon, which results from the\nkinetic arrest of the first order magnetic phase transition. Interesting\nproperties, such as metastable magnetization and nonequilibrium magnetic\nphases, are naturally developed in the magnetic glassy state. Here, we report\nmagnetic glass property in the low spin state of Co3+ in EuBaCo2O5+{\\delta}\n({\\delta} = 0.47) cobaltite at low temperature (T < 60 K). The measurements of\nmagnetization under the cooling and heating in unequal fields, magnetization\nrelaxation and thermal cycling of magnetization show the kinetic arrest of low\nmagnetization state below 60 K. The kinetically arrested low temperature\nmagnetic phase is further supported through the study of isothermal magnetic\nentropy, which shows the significant entropy change. The present results will\nopen a new window to search the microscopic relation between the spin state\ntransitions and the kinetic arrest induced magnetic glassy phenomena in complex\nmaterials.",
        "positive": "Carrier induced ferromagnetic interactions in p-doped Zn(1-x)MnxTe\n  epilayers: p-type doping of molecular-beam-epitaxy grown layers of the diluted magnetic\nsemiconductor Zn(1-x)MnxTe is achieved by using an active nitrogen cell. The\nstrong interaction between the localized Mn spins and the holes deeply modifies\nthe transport properties (metal-insulator transition, spin-dependent Hall\neffect). In spite of the weak localization of the carriers at low temperature,\nthe holes clearly induce a ferromagnetic interaction between the localized\nspins, which is discussed as a function of Mn content and hole concentration."
    },
    {
        "anchor": "Role of Ca off-centering in tuning the ferroelectric phase transitions\n  in Ba(Zr,Ti)O3 system: We here report the substitution effects of the smaller Ca for the bulky Ba in\n(Ba1-xCax)(Ti1-yZry)O3 perovskite oxides for two systems (Ba1-xCax)TiO3 with\ny=0 and (Ba1-xCax)(Ti0.9Zr0.1)O3 with y=0.1. Ca off-centering was found to play\na critical role in stabilizing the ferroelectric phase and tuning the\npolarization states in both systems. It was demonstrated that the atomic\ndisplacement due to Ca off-centering in the bulky Ba-site in the perovskite\nstructure provides an effective approach to compensate the reduction of\nferroelectricity due to the chemical pressure, which allows to keep the Curie\npoint nearly constant in the (Ba1-xCax)TiO3 system and increase the Curie point\nin the (Ba1-xCax)(Ti0.9Zr0.1)O3 system. It was commonly observed that the Ca\noff-centering effects lead to the shift of the R-O and O-T phase transitions\ntoward lower temperatures and the ferroelectric stability of the T-phase,\nresulting in the occurrence of quantum phase transitions with interesting\nphysics phenomena at low temperatures in the (Ba1-xCax)TiO3 system and the\ngreat enhancement of electromechanical coupling effects around room temperature\nin the (Ba1-xCax)(Ti0.9Zr0.1)O3 system over a wide composition range of the\nCa-concentration. These finding may be of great interest for the design of the\ngreen piezoelectric materials.",
        "positive": "Band Structure and Effective Masses of ZnMgO: We analyze the influence of the Mg concentration on several important\nproperties of the band structure of ZnMgO alloys in wurtzite structure using ab\ninitio calculations. For this purpose, the band structure for finite\nconcentrations is defined in terms of the Bloch spectral density, which can be\ncalculated within the coherent potential approximation. We investigate the\nconcentration dependence of the band gap and the crystal-field splitting of the\nvalence bands. The effective electron and hole masses are determined by\nextending the effective mass model to finite concentrations. We compare our\nresults with experimental results and other calculations."
    },
    {
        "anchor": "Comment on \"Highly Extended Image States around Nanotubes\": A Comment on the Letter by Granger et.al., Phys. Rev. Lett. 89, 135506\n(2002).",
        "positive": "Ultra fast bit addressing in a magnetic memory matrix with crossed wire\n  write line geometry: An ultra fast bit addressing scheme for magnetic random access memories\n(MRAM) in a crossed wire geometry is proposed. In the addressing scheme a word\nof cells is programmed simultaneously by sub nanosecond field pulses making use\nof the magnetization precession of the free layer. Single spin simulations of\nthe free layer dynamics show that the pulse parameters for programming an\narbitrary word of the array can be chosen such that the magnetization of the\ncells to be written performs either a half or a full precessional turn during\napplication of the programming pulse depending on the initial and final\nmagnetization orientation of the addressed cells. Such bit addressing scheme\nleads to a suppression of the magnetization ringing in all cells of the memory\narray thereby allowing ultra high MRAM write clock rates above 1 GHz."
    },
    {
        "anchor": "CO Oxidation Catalysed by Pd-based Bimetallic Nanoalloys: Density functional theory based global geometry optimization has been used to\ndemonstrate the crucial influence of the geometry of the catalytic cluster on\nthe energy barriers for the CO oxidation reaction over Pd-based bimetallic\nnanoalloys. We show that dramatic geometry change between the reaction\nintermediates can lead to very high energy barriers and thus be prohibitive for\nthe whole process. This introduces challenges for both the design of new\ncatalysts, and theoretical methods employed. On the theory side, a careful\nchoice of geometric configurations of all reaction intermediates is crucial for\nan adequate description of a possible reaction path. From the point of view of\nthe catalyst design, the cluster geometry can be controlled by adjusting the\nlevel of interaction between the cluster and the dopant metal, as well as\nbetween the adsorbate molecules and the catalyst cluster by mixing different\nmetals in a single nanoalloy particle. We show that substitution of a Pd atom\nin the Pd$_{5}$ cluster with a single Ag atom to form Pd$_{4}$Ag$_{1}$ leads to\na potential improvement of the catalytic properties of the cluster for the CO\noxidation reaction. On the other hand, a single Au atom does not enhance the\nproperties of the catalyst, which is attributed to a weaker hybridization\nbetween the cluster's constituent metals and the adsorbate molecules. Such\nflexibility of properties of bimetallic nanoalloy clusters illustrates the\npossibility of fine-tuning, which might be used for design of novel efficient\ncatalytic materials.",
        "positive": "Excitation Amplitude Dependence of Low Frequency Magneto-impedance of\n  Amorphous Fe73.5Nb3Cu1Si13.5B9 Ribbon: Magneto-impedance (MI) of soft ferromagnetic materials is a sensitive\nfunction of the amplitude and frequency of exciting a.c magnetic field. MI (Z)\nof amorphous ferromagnetic ribbon of nominal composition Fe73.5Nb3 Cu1 Si13.5\nB9 is measured at different excitation currents with frequency ranging from\n30kHz to 120KHz The excitation (a.c) and biasing (d.c) magnetic fields Hdc are\nparallel to ribbon axis. At zero dc fields, Z exhibits non-linear dependence on\nexcitation amplitude whereas at higher d.c fields (9Oe) Z is nearly independent\nof excitation amplitude. The impedance is maximum at zero bias field and\nsharply decreases as Hdc increases and almost zero hysterisis has been observed\nas Hdc is scanned. The maximum relative change of impedance\n(Z(H)-Z(H=0))/Z(H=0) is found to increase from nearly 45 to 60 percent when the\nexcitation fields goes up from 14A/m to 140A/m. The large MI is associated with\nscreening of electromagnetic field by magnetization induced by exciting ac\nfield."
    },
    {
        "anchor": "First-Principle Characterization of Structural, Electronic, and Optical\n  Properties of Tin-Halide Monomers: The growing interest in tin-halide semiconductors for photovoltaic\napplications demands an in-depth knowledge of the fundamental properties of its\nconstituents, starting from the smallest monomers entering the initial stages\nof formation. In this first-principles work based on time-dependent\ndensity-functional theory, we investigate the structural, electronic, and\noptical properties of tin-halide molecules SnX$_n^{2-n}$, with $n=1,2,3,4$ and\nX = Cl, Br, I, simulating these compounds in vacuo as well as in an implicit\nsolvent. We find that structural properties are very sensitive to the halogen\nspecies while the charge distribution is also affected by stoichiometry. The\nionicity of the Sn-X bond is confirmed by the Bader charge analysis albeit\ncharge displacement plots point to more complex metal-halide coordination.\nParticular focus is posed on the neutral molecules SnX$_2$, for which\nelectronic and optical properties are discussed in detail. Band gaps and\nabsorption onset decrease with increasing size of the halogen species and\ndespite general common features, each molecule displays peculiar optical\nsignatures. Our results are elaborated in the context of experimental and\ntheoretical literature, including the more widely studied lead-halide analogs,\naiming to contribute with microscopic insight to a better understanding of\ntin-halide perovskites.",
        "positive": "Discovery of Atomic Clock-Like Spin Defects in Simple Oxides from First\n  Principles: Virtually noiseless due to the scarcity of spinful nuclei in the lattice,\nsimple oxides hold promise as hosts of solid-state spin qubits. However, no\nsuitable spin defect has yet been found in these systems. Using high-throughput\nfirst-principles calculations, we predict spin defects in calcium oxide with\nelectronic properties remarkably similar to those of the NV center in diamond.\nThese defects are charged complexes where a dopant atom -- Sb, Bi, or I --\noccupies the volume vacated by adjacent cation and anion vacancies. The\npredicted zero phonon line shows that the Bi complex emits in the\ntelecommunication range, and the computed many-body energy levels suggest a\nviable optical cycle required for qubit initialization. Notably, the high-spin\nnucleus of each dopant strongly couples to the electron spin, leading to many\ncontrollable quantum levels and the emergence of atomic clock-like transitions\nthat are well protected from environmental noise. Specifically, the Hanh-echo\ncoherence time increases beyond seconds at the clock-like transition in the\ndefect with \\ch{^{209}Bi}. Our results pave the way to designing quantum states\nwith long coherence times in simple oxides, making them attractive platforms\nfor quantum technologies."
    },
    {
        "anchor": "Low temperature carrier transport mechanism and photoconductivity of\n  WSe2: This work reports the electrical transport and temperature-dependent\nphotoconductivity in tungsten diselenide (WSe2) thin films. The electrical\nconductivity analysis shows the presence of the three regions with temperature\nvariation. At lower temperatures (<190K), carriers become localized to small\nregions in the film due to the Mott hopping mechanism. The middle region (190\nto 273 K) follows Seto parameters and obtained low barrier height (0.0873 eV)\nmay be responsible for the improved carrier mobility. At higher temperature\n(>273K) region, thermally activated conduction is dominated with two activation\nenergies of ~138 meV and 98 meV. The peaks obtained in photoluminescent\nanalysis attributes to the presence of mid-bandgap states or defect states\nwhich play an important role in the photoconductivity of WSe2. The transient\nphotoconductivity measurements show consistent temperature-dependent behaviour.\nThe effect of light intensity and wavelength variation on the photoconductivity\nof WSe2 thin films is also discussed. The photocurrent is 1.19*10-5 A at 125 K\nwhile at 350 K it was observed to be 3.12*10-4 A. The light-on/off current\ncycles show that the current can recover to its initial state which points to\nthe stable and outstanding reversible properties of the WSe2 thin film device\nto be used in photodetector applications.",
        "positive": "Measurement of High-temperature Thermophysical Properties of Bulk and\n  Coatings Using Modulated Photothermal Radiometry: This paper presents the development of instrumentation for the measurement of\nhigh-temperature thermal conductivity of bulk and coatings using a modulated\nphotothermal radiometry (MPR) method, where a sample is heated by an\nintensity-modulated laser to probe into different layers of the sample. While\nMPR has been previously established, most of the previous studies only focus on\nthe measurement at room temperature. The MPR has not been well studied for\nmeasurements of bulk and coating materials at high temperatures, which are\nincreasingly important for a multitude of applications, such as materials used\nin the concentrating solar power (CSP) plants and the nuclear reactors. MPR is\na non-contact technique that utilizes the intrinsic thermal emission from the\nspecimens for thermometry, which is favorable for measurements at high\ntemperatures in harsh environment. The authors designed and utilized a sample\nholder suitable for high temperature measurement up to 973 K with good\ntemperature uniformity within the sample. The high-temperature MPR setup was\nvalidated by measuring bulk materials with known thermal conductivity. The\nsetup and technique were then extended to the measurement of black\nsolar-absorbing coatings of 10 to 50 {\\mu}m thick on various substrates by\nmodulating the frequency of the laser heating beam and the thermal penetration\ndepth. The studies showed that thermal conductivities of typical\nsolar-absorbing coatings are 0.4 ~ 0.8 W m-1 K-1, indicating a possibly large\ntemperature drop within the coating under high solar irradiation flux, such as\nover 1000-sun for central solar towers in CSP plants."
    },
    {
        "anchor": "Size effects in the toughening of brittle materials by heterogeneities:\n  a non-linear analysis of front deformations: Traditional computational approaches in simulating crack propagation in\nperfectly brittle materials rely on the estimate of stress intensity factors\nalong the rupture front. This proves highly challenging in 3D when the crack\ngeometry departs from very specific cases for which analytical solutions are\navailable, like e.g. the penny-shaped crack geometry. Here, we extend the\nfirst-order theory of Gao and Rice (1987), and predict the distribution of the\nmode I stress intensity factor $K_\\mathrm{I}$ along the front of a tensile\ncoplanar crack that is slightly perturbed from a reference penny-shaped\nconfiguration, up to second order in the perturbation amplitude. Our theory is\nvalidated against analytical solutions available for embedded elliptical\ncracks, and its range of validity is further assessed using numerical\nsimulations performed on cosine front perturbations of varying mode and\namplitude. It is then used to develop a homogenization framework for the\ntoughness of weakly disordered media. The effective toughness and its\nfluctuations are bridged quantitatively to the intensity of the toughness\nfluctuations and their spatial structure. Our theoretical predictions are\ncompared to the results of ~1 million simulations of crack propagation building\non our second-order theory and Fast Fourier Transforms. We show that the impact\nof toughness heterogeneities is size-dependent, as they generally weaken the\nmaterial when the crack size is lower or comparable to the typical\nheterogeneity size, but reinforces it otherwise. It results in an apparent\nR-curve behavior of the brittle composite at the macroscale.",
        "positive": "Inferring topological transitions in pattern-forming processes with\n  self-supervised learning: The identification and classification of transitions in topological and\nmicrostructural regimes in pattern-forming processes are critical for\nunderstanding and fabricating microstructurally precise novel materials in many\napplication domains. Unfortunately, relevant microstructure transitions may\ndepend on process parameters in subtle and complex ways that are not captured\nby the classic theory of phase transition. While supervised machine learning\nmethods may be useful for identifying transition regimes, they need labels\nwhich require prior knowledge of order parameters or relevant structures\ndescribing these transitions. Motivated by the universality principle for\ndynamical systems, we instead use a self-supervised approach to solve the\ninverse problem of predicting process parameters from observed microstructures\nusing neural networks. This approach does not require predefined, labeled data\nabout the different classes of microstructural patterns or about the target\ntask of predicting microstructure transitions. We show that the difficulty of\nperforming the inverse-problem prediction task is related to the goal of\ndiscovering microstructure regimes, because qualitative changes in\nmicrostructural patterns correspond to changes in uncertainty predictions for\nour self-supervised problem. We demonstrate the value of our approach by\nautomatically discovering transitions in microstructural regimes in two\ndistinct pattern-forming processes: the spinodal decomposition of a two-phase\nmixture and the formation of concentration modulations of binary alloys during\nphysical vapor deposition of thin films. This approach opens a promising path\nforward for discovering and understanding unseen or hard-to-discern transition\nregimes, and ultimately for controlling complex pattern-forming processes."
    },
    {
        "anchor": "Spin-orbit coupling tuned crossover of gaped and gapless topological\n  phases in the chalcopyrite HgSnX 2 (X=N/P): An ab-initio investigation: The coupling between electron orbital momentum and spin momentum, known as\nspin-orbit coupling (SOC), is a fundamental origin of a multitude of\nfascinating physical phenomena, especially it holds paramount significance in\nthe realm of topological materials. In our work, we have predicted the\ntopological phase in Hg-based chalcopyrite compounds using the first principles\ndensity functional theory. The initial focus was on HgSnN 2 , revealing it to\nbe a nonmagnetic Weyl semimetal, while HgSnP 2 displayed characteristics of a\nstrong topological insulator. What makes our work truly unique is that despite\nboth compounds having the same SOC strength, arises from Hg, they exhibit\ndistinct topological phases due to the distinct hybridization effect of the\nHg-5d and X-p bands. This finding can address a significant factor, i.e., the\neffect of the band hybridization in deriving distinct topological phases,\nkeeping the symmetry aspect intact. Our results indicate that due to the\npresence of band hybridization between the dominant X-np orbitals n=2 and 3 for\nX=N and P respectively and a minor contribution from Hg-5d, we can tune the\ntopological phase by manipulating SOC strength, which equivalently achievable\nby chemical substitutions. This investigation stands as a remarkable\nillustration of the unique roles that hybridization plays in sculpting the\ntopological properties of these compounds while simultaneously preserving their\nunderlying symmetries.",
        "positive": "Dislocations as natural quantum wires in Diamond: We study the electronic properties of the glide set of dislocations in\ndiamond from first principles using hybrid exchange correlation functionals and\nfind that the atomic-scale dislocation core states give rise to a prototypical\none-dimensional (1D) band structure, i.e. natural quantum wires. The position\nand character of the core states varies strongly with local structure, where\nmixed dislocations with dangling bonds exhibit a 1D metallic band with a\ncharacteristic 1D density of states ($1/\\sqrt{E})$. This 1D Fermi gas is\nspatially localized to single atomic diameter orbital chain along the\ndislocation core. When the dangling bonds within the core are reconstructed,\nthe 1D metallic band disappears. In contrast, pure edge dislocations in diamond\nreveal a 1D semiconductor with a direct band gap of 3.0 eV. These calculations\nprovide a possible explanation to the long standing observation of a blue\nluminescence band correlated with dislocations in diamond. This opens the door\nto using dislocations as 1D quantum phases with functional (electronic and\noptical) properties arising from the atomic-scale core states."
    },
    {
        "anchor": "Heat transport in silicon from first principles calculations: Using harmonic and anharmonic force constants extracted from\ndensity-functional calculations within a supercell, we have developed a\nrelatively simple but general method to compute thermodynamic and thermal\nproperties of any crystal. First, from the harmonic, cubic, and quartic force\nconstants we construct a force field for molecular dynamics (MD). It is exact\nin the limit of small atomic displacements and thus does not suffer from\ninaccuracies inherent in semi-empirical potentials such as Stillinger-Weber's.\nBy using the Green-Kubo (GK) formula and molecular dynamics simulations, we\nextract the bulk thermal conductivity. This method is accurate at high\ntemperatures where three-phonon processes need to be included to higher orders,\nbut may suffer from size scaling issues. Next, we use perturbation theory\n(Fermi Golden rule) to extract the phonon lifetimes and compute the thermal\nconductivity $\\kappa$ from the relaxation time approximation. This method is\nvalid at most temperatures, but will overestimate $\\kappa$ at very high\ntemperatures, where higher order processes neglected in our calculations, also\ncontribute. As a test, these methods are applied to bulk crystalline silicon,\nand the results are compared and differences discussed in more detail. The\npresented methodology paves the way for a systematic approach to model heat\ntransport in solids using multiscale modeling, in which the relaxation time due\nto anharmonic 3-phonon processes is calculated quantitatively, in addition to\nthe usual harmonic properties such as phonon frequencies and group velocities.\nIt also allows the construction of accurate bulk interatomic potentials\ndatabase.",
        "positive": "Understanding glassy phenomena in materials: A basis for understanding and modelling glassy behaviour in martensitic\nalloys and relaxor ferroelectrics is discussed from the perspective of spin\nglasses."
    },
    {
        "anchor": "Miniaturized Double-Wing Delta-E Effect Sensors: Magnetoelastic composites are integral elements of sensors and actuators\nutilizing magnetostriction for their functionality. Their sensitivity typically\nscales with the saturation magnetostriction and inversely with magnetic\nanisotropy. However, this makes the devices prone to minuscule residual\nanisotropic stress from the fabrication process, impairing their performance\nand reproducibility, hence limiting their suitability for arrays. This study\npresents a shadow mask deposition technology combined with a free-free\nmagnetoelectric microresonator design intended to minimize residual stress and\ninhomogeneity in the magnetoelastic layer. Resonators are experimentally and\ntheoretically analyzed regarding local stress anisotropy, magnetic anisotropy,\nand the {\\Delta}E effect in several resonance modes. Further, the sensitivity\nis analyzed in the example of {\\Delta}E-effect sensors. The results demonstrate\na device-to-device variation of the resonance frequency < 0.2 % with\nsensitivities comparable with macroscopic {\\Delta}E-effect sensors. The\nreproducibility is drastically improved over previous magnetoelastic device\narrays. This development marks a step forward in the reproducibility and\nhomogeneity of magnetoelastic resonators and contributes to the feasibility of\nlarge-scale, integrated sensor arrays.",
        "positive": "Inelastic Light Scattering Spectroscopy of Magnons and Phonons in Nickel\n  Oxide: Effects of Temperature: We report results of an investigation of the temperature dependence of the\nmagnon and phonon frequencies in NiO. A combination of Brillouin - Mandelstam\nand Raman spectroscopies allowed us to elucidate the evolution of the phonon\nand magnon spectral signatures from the Brillouin zone center (GHz range) to\nthe second-order peaks from the zone boundary (THz range). The\ntemperature-dependent behavior of the magnon and phonon bands in the NiO\nspectrum indicates the presence of antiferromagnetic (AF) order fluctuation or\na persistent AF state at temperatures above the Neel temperature (T=523 K).\nTuning the intensity of the excitation laser provides a method for\ndisentangling the features of magnons from acoustic phonons without the\napplication of a magnetic field. Our results are useful for interpretation of\nthe inelastic-light scattering spectrum of NiO, and add to the knowledge of its\nmagnon properties important for THz spintronic devices."
    },
    {
        "anchor": "$\\mathrm{Fe}_{1-x}\\mathrm{Ni}_x$ Alloy Nanoparticles Encapsulated inside\n  Carbon Nanotubes: Controlled Synthesis, Structure and Magnetic Properties: In the present work, different synthesis procedures have been demonstrated to\nfill carbon nanotubes (CNTs) with $\\mathrm{Fe}_{1-x}\\mathrm{Ni}_x$ alloy\nnanoparticles (x = 0.33, 0.5). CNTs act as templates for the encapsulation of\nmagnetic nanoparticles, and provide a protective shield against oxidation as\nwell as prevent nanoparticles agglomeration. By variation of the reaction\nparameters, the purity of the samples, degree of filling, the composition and\nsize of filling nanoparticles have been tailored and therefore the magnetic\nproperties. The samples were analyzed by scanning electron microscopy (SEM),\ntransmission electron microscopy (TEM), Bright-field (BF) TEM tomography, X-ray\npowder diffraction, superconducting quantum interference device (SQUID) and\nthermogravimetric analysis (TGA). The Fe1-xNix-filled CNTs show a huge\nenhancement in the coercive fields compared to the corresponding bulk\nmaterials, which make them excellent candidates for several applications such\nas magnetic storage devices.",
        "positive": "Ferroelectricity and chirality in the Pb$_5$Ge$_3$O$_{11}$ crystal: We study from first-principles calculations the ferroelectric structural\nphase transition of Pb$_5$Ge$_3$O$_{11}$ crystal. The calculations of phonons\nand Born effective charges of the paraelectric phase allow us to identify a\npolar instability that is unstable in both transverse-optic and\nlongitudinal-optic versions, giving rise to an entire branch of instability\nalong a propagation vector parallel to the mode polarization (the hexagonal\naxe). This is the hint of hyperferroelectricity and the stable head-to-head and\ntail-to-tail domain, as recently reported from both experiments and theory.\nThen, our analysis of the ferroelectric phase shows that the polarization of\nPb$_5$Ge$_3$O$_{11}$ is uniaxial along the hexagonal axes and with small\nin-plane components due to a piezoelectric effect. The symmetry-adapted mode\nanalysis shows that the total ferroelectric ground state distortion comes\nmainly from polar distortions of the unstable polar phonon mode but also from\nan invariant, cooperative mode that amplifies the polar deformation. We also\nbuild a phenomenological model that highlights how the coupling between these\nmodes is at play and helps us understand how to reproduce the second-order\nphase transition. At last, we also quantify the structural chirality through\nthe continuous symmetry measure method and trace its origin to the polar\nunstable mode itself. By extending our approach to the phonon states we further\nshow that the chirality is poorly affected by the relaxation but could also be\nenhanced by activating high frequency modes with polar symmetry. Finally we\nstudy the phonon angular momentum (AM) distribution in both phases and identify\ntrends in the AM behaviour across the Brillouin zone."
    },
    {
        "anchor": "Strong impact of the eddy-current shielding on ferromagnetic resonance\n  response of sub-skin-depth-thick conducting magnetic multilayers: Exchange-coupled nonmagnetic (NM) and ferromagnetic (FM) conducting\nmultilayers are crucial for microwave spintronic devices of the future. We\ndemonstrate, experimentally and theoretically, that in broadband measurements\nof ferromagnetic resonance (FMR) 10-70 nm-thick permalloy (Py) layers are\nshielded from the dynamic magnetic field of the microstrip line by eddy\ncurrents circulating in the NM capping layers, which strongly diminishes the\namplitude of magnetisation precession in the FM material. Our findings have\ndirect implications for designing broadband FMR and measurements of spin\ncurrent injection through interfaces realised by placing a conducting\nmultilayer above a microwave microstrip line. We show that the eddy-current\nshielding is very strong at high microwave frequencies (30 GHz) even when the\nthickness of the NM capping layer is <5 nm, which is well below the microwave\nskin depth for Au, Cu, Ta, Pd, Pt and other NM metals technologically important\nfor spintronics.",
        "positive": "Damage Localisation in Fresh Cement Mortar Observed via In Situ\n  (Timelapse) X-ray \u03bcCT imaging: This paper studies the evolution of internal damage in fresh cement mortar\nover the 25 hours of hardening. In situ timelapse X-ray computed\nmicro-tomography ({\\mu}XCT) imaging method was used to detect internal damage\nand capture its evolution in cement hydration. During {\\mu}XCT scans, the\nhydration heat was measured, which provided insight for the internal damage\nevolution with a link to hydration heat development. The measured hydration\nheat was compared with an analytical prediction, which showed a relatively good\nagreement with the experimental data. Using 20 CT scans acquired throughout the\nobserved cement hydration, it was possible to obtain a quantified\ncharacterisation of the porous space. Additionally, the use of timelapse\n{\\mu}XCT imaging over 25 hours allowed to study the crack growth inside of the\nmeso-structure including its volume and surface. Observed results provide\nvaluable insights to cement mortar shrinkage."
    },
    {
        "anchor": "Tuning the Magnetic and Electronic Properties of Strontium Titanate by\n  Carbon Doping: The magnetic and electronic properties of strontium titanate with different\ncarbon dopant configurations are explored using first-principles calculations\nwith a generalized gradient approximation (GGA) and the GGA+U approach. Our\nresults show that the structural stability, electronic properties and magnetic\nproperties of C-doped SrTiO3 strongly depend on the distance between carbon\ndopants. In both GGA and GGA+U calculations, the doping structure is mostly\nstable with a nonmagnetic feature when the carbon dopants are nearest\nneighbors, which can be ascribed to the formation of a C-C dimer pair\naccompanied by stronger C-C and weaker C-Ti hybridizations as the C-C distance\nbecomes smaller. As the C-C distance increases, C-doped SrTiO3 changes from an\nn-type nonmagnetic metal to ferromagnetic/antiferromagnetic half-metal and to\nan antiferromagnetic/ferromagnetic semiconductor in GGA calculations, while it\nchanges from a nonmagnetic semiconductor to ferromagnetic half-metal and to an\nantiferromagnetic semiconductor using the GGA+U method. Our work demonstrates\nthe possibility of tailoring the magnetic and electronic properties of C-doped\nSrTiO3, which might provide some guidance to extend the applications of\nstrontium titanate as a magnetic or optoelectronic material.",
        "positive": "Diluted magnetic semiconductors with narrow band gaps: We propose a method to realize diluted magnetic semiconductors (DMS) with p-\nand n-type carriers by choosing host semiconductors with a narrow band gap. By\nemploying a combination of the density function theory and quantum Monte Carlo\nsimulation, we demonstrate such semiconductors using Mn-doped BaZn2As2, which\nhas a band gap of 0.2 eV. In addition, we found a new non-toxic DMS Mn-doped\nBaZn2Sb2, of which the Curie temperature Tc is predicted to be higher than that\nof Mn-doped BaZn2As2, the Tc of which was up to 230 K in the recent experiment."
    },
    {
        "anchor": "Accounting for localized deformation: a simple computation of true\n  stress in micropillar compression experiments: Compression experiments are widely used to study the mechanical properties of\nmaterials at micro- and nanoscale. However, the conventional engineering stress\nmeasurement method used in these experiments neglects to account for the\nalterations in the material's shape during loading. This can lead to inaccurate\nstress values and potentially misleading conclusions about the material's\nmechanical behavior especially in the case of localized deformation. To address\nthis issue, we present a method for calculating true stress in cases of\nlocalized plastic deformation commonly encountered in experimental settings:\n(i) a single band and (ii) two bands oriented in arbitrary directions with\nrespect to the vertical axis of the pillar (either in the same or opposite\ndirections). Our simple analytic formulas can be applied to homogeneous and\nisotropic materials and crystals, requiring only standard data\n(displacement-force curve, aspect ratio, shear band angle and elastic strain\nlimit) obtained from experimental results and eliminating the need for finite\nelement computations. Our approach provides a more precise interpretation of\nexperimental results and can serve as a valuable and simple tool in material\ndesign and characterization.",
        "positive": "Semi-metallicity and electron-hole liquid in two-dimensional C and BN\n  based compounds: Insulating-metallic transition mediated by substitutional atoms is predicted\nin a series of two-dimensional carbon-based structures. Introducing Si atoms in\nselected sites of tetrahexcarbon [Carbon 137 (2018) 266] according to rational\nchemical rules, metallicity by trivial band inversion without band gap opening\nis induced. Additional substitution of remaining C atoms by BN dimers\nintroduces no changes in the metallic properties. A series of isomorphous\ntwo-dimensional materials with isoelectronic structures derived by exchanging\ngroup IV elements exhibiting various band gaps is obtained. Dynamical stability\nis verified with phonon analysis and beyond the harmonic approximation with\nmolecular dynamics up to room temperature. The semi-metallic compounds have\nwell-nested pockets of carriers and are good candidates for the formation of an\nexcitonic insulator."
    },
    {
        "anchor": "Tuning of Berry Curvature Dipole in TaAs slabs: An effective Route to\n  Enhance Nonlinear Hall Response: In materials without inversion symmetry, Berry curvature dipole (BCD) arises\nfrom the uneven distribution of Berry curvature in momentum space. This leads\nto nonlinear anomalous Hall effects even in systems with preserved\ntime-reversal symmetry. A key goal is to engineer systems with prominent BCD\nnear the Fermi level. Notably, TaAs, a type-I Weyl semimetal, exhibits\nsubstantial Berry curvature but a small BCD around the Fermi level. In this\nstudy, we employed first-principles methods to comprehensively investigate the\nBCD in TaAs. Our findings reveal significant cancellation effects not only\nwithin individual Weyl points but crucially, among distinct Weyl point pairs in\nbulk TaAs. We propose a strategic approach to enhance the BCD in TaAs by\nemploying a layer-stacking technique. This greatly amplifies the BCD compared\nto the bulk material. By tuning the number of slab layers, we can selectively\ntarget specific Weyl point pairs near the Fermi level, while quantum\nconfinement effects suppress contributions from other pairs, mitigating\ncancellation effects. Especially, the BCD of an 8-layer TaAs slab surpasses the\nbulk value near the Fermi level by orders of magnitude.",
        "positive": "Bayesian inference to identify crystalline structures for XRD: Crystalline phase structure is essential for understanding the performance\nand properties of a material. Therefore, this study identified and quantified\nthe crystalline phase structure of a sample based on the diffraction pattern\nobserved when the crystalline sample was irradiated with electromagnetic waves\nsuch as X-rays. Conventional analysis necessitates experienced and\nknowledgeable researchers to shorten the list from many candidate crystalline\nphase structures. However, the Conventional diffraction pattern analysis is\nhighly analyst-dependent and not objective. Additionally, there is no\nestablished method for discussing the confidence intervals of the analysis\nresults. Thus, this study aimed to establish a method for automatically\ninferring crystalline phase structures from diffraction patterns using Bayesian\ninference. Our method successfully identified true crystalline phase structures\nwith a high probability from 50 candidate crystalline phase structures.\nFurther, the mixing ratios of selected crystalline phase structures were\nestimated with a high degree of accuracy. This study provided reasonable\nresults for well-crystallized samples that clearly identified the crystalline\nphase structures."
    },
    {
        "anchor": "Structural tunability and origin of two-level systems in amorphous\n  silicon: Amorphous silicon films prepared by electron beam evaporation have\nsystematically and substantially greater atomic density for higher thickness,\nhigher growth temperature, and slower deposition rate, reaching the density of\ncrystalline Si when films of thickness greater than ~300 nm are grown at 425\n$^{\\circ}$C and at <1 $\\r{A}$/sec. A combination of spectroscopic techniques\nprovide insight into atomic disorder, local strains, dangling bonds, and\nnanovoids. Electron diffraction shows that the short-range order of the\namorphous silicon is similar at all growth temperatures, but fluctuation\nelectron microscopy shows that films grown above room-temperature show a form\nof medium-range order not previously observed in amorphous silicon. Atomic\ndisorder and local strain obtained from Raman spectroscopy reduce with\nincreasing growth temperature and show a non-monotonic dependence on thickness.\nDangling bond density decreases with increasing growth temperature and is only\nmildly dependent on thickness. Positron annihilation Doppler broadening\nspectroscopy and electron energy loss spectroscopy show that nanovoids, and not\ndensity variations within the network, are responsible for reduced atomic\ndensity. Specific heat and mechanical loss measurements, which quantify the\ndensity of tunneling two-level systems, in combination with the structural\ndata, suggest that two-level systems in amorphous silicon films are associated\nwith nanovoids and their surroundings; which are in essence loosely bonded\nregions where atoms are less constrained.",
        "positive": "Unusual dynamics of Fe atoms in chromium matrix: 57Fe site Mossbauer Spectroscopy (MS) was used to investigate a dynamics of\n57Fe atoms embedded into chromium lattice as impurities. From the Mossbauer\nspectra recorded in the temperature range of 80 to 350 K, a temperature\ndependence of the Lamb-Mossbauer factor, f, was determined. The latter revealed\nan unusual dynamics of 57Fe atoms viz. harmonic mode below T = 145 K with a\ncharacteristic effective Debye temperature, Qeff = 185 K and anharmonic one\nabove T o 145 K. The latter mode exists in two clearly separated temperature\nintervals with slightly different Qeff - values viz. (i) 156 K for 145 K < T <\n240 K and the record-high anharmonic coefficient e = 18 * 10-4 K-1 and (ii) 152\nK for T > 240 K and e = 13.6 * 10-4 K-1. Based on the Visscher's theory, the\nrecord-low values of relative binding force constants for Fe atoms were\ndetermined as 0.0945, 0.0673 and 0.0634, respectively. It is suggested that the\nunusual dynamics observed in this study might be related to the underlying\nspin- and charge- and strain-density waves of chromium."
    },
    {
        "anchor": "Pivotal Role of Intersite Hubbard Interactions in Fe-doped\n  $\u03b1$-MnO$_2$: We present a first-principles investigation of the structural, electronic,\nand magnetic properties of the pristine and Fe-doped $\\alpha$-MnO$_2$ using\ndensity-functional theory with extended Hubbard functionals. The onsite $U$ and\nintersite $V$ Hubbard parameters are determined from first principles and\nself-consistently using density-functional perturbation theory in the basis of\nL\\\"owdin-orthogonalized atomic orbitals. For the pristine $\\alpha$-MnO$_2$ we\nfind that the so-called C2-AFM spin configuration is the most energetically\nfavorable, in agreement with the experimentally observed antiferromagnetic\nground state. For the Fe-doped $\\alpha$-MnO$_2$ two types of doping are\nconsidered: Fe insertion in the $2 \\times 2$ tunnels and partial substitution\nof Fe for Mn. We find that the interstitial doping preserves the C2-AFM spin\nconfiguration of the host lattice only when both onsite $U$ and intersite $V$\nHubbard corrections are included, while for the substitutional doping the\nonsite Hubbard $U$ correction alone is able to preserve the C2-AFM spin\nconfiguration of the host lattice. The oxidation state of Fe is found to be\n$+2$ and $+4$ in the case of the interstitial and substitutional doping,\nrespectively, while the oxidation state of Mn is $+4$ in both cases. This work\npaves the way for accurate studies of other MnO$_2$ polymorphs and complex\ntransition-metal compounds when the localization of $3d$ electrons occurs in\nthe presence of strong covalent interactions with ligands.",
        "positive": "Temperature dependence of the pre-edge structure in the Ti K-edge x-ray\n  absorption spectrum of rutile: The temperature dependence of the pre-edge features in x-ray absorption\nspectroscopy is reviewed. Then, the temperature dependence of the pre-edge\nstructure at the K-edge of titanium in rutile TiO2 is measured at low and room\ntemperature. The first two peaks grow with temperature. The fact that these two\npeaks also correspond to electric quadrupole transitions is explained by a\nrecently proposed theory."
    },
    {
        "anchor": "Finite-temperature properties of non-magnetic transition metals:\n  Comparison of the performance of constraint-based semi and nonlocal\n  functionals: We assess the performance of nonempirical, truly nonlocal and semi-local\nfunctionals with regard to structural and thermal properties of $3d$, $4d$, and\n$5d$ non-magnetic transition metals. We focus on constraint-based functionals\nand consider the new consistent-exchange van der Waals density functional\nversion vdW-DF-cx [Phys. Rev. B 89, 035412 (2014)], the semi-local PBE [Phys.\nRev. Lett. 77, 3865 (1996)] and PBEsol functionals [Phys. Rev. Lett. 100,\n136406 (2008)] as well as the AM05 meta-functional [Phys. Rev. B 72, 085108\n(2005)]. Using the quasi-harmonic approximation structural parameters, elastic\nresponse, and thermal expansion at finite temperatures are computed and\ncompared to experimental data. We also compute cohesive energies explicitly\nincluding zero-point vibrations. It is shown that overall vdW-DF-cx provides an\naccurate description of thermal properties and retains a level of\ntransferability and accuracy that is comparable to or better than some of the\nbest constraint-based semi-local functionals. Especially, with regard to the\ncohesive energies the consistent inclusion of spin polarization effects in the\natoms turns out to be crucial and it is important to use the rigorous\nspin-vdW-DF-cx formulation [Phys. Rev. Lett. 115, 136402 (2015)]. This\ndemonstrates that vdW-DF-cx has general-purpose character and can be used to\nstudy systems that have both sparse and dense electron distributions.",
        "positive": "Non-piezoelectric effects in piezoresponse force microscopy: Piezoresponse force microscopy (PFM) has been used extensively for exploring\nnanoscale ferro/piezoelectric phenomena over the past two decades. The imaging\nmechanism of PFM is based on the detection of the electromechanical (EM)\nresponse induced by the inverse piezoelectric effect through the cantilever\ndynamics of an atomic force microscopy. However, several non-piezoelectric\neffects can induce additional contributions to the EM response, which often\nlead to a misinterpretation of the measured PFM response. This review aims to\nsummarize the non-piezoelectric origins of the EM response that impair the\ninterpretation of PFM measurements. We primarily discuss two major\nnon-piezoelectric origins, namely, the electrostatic effect and electrochemical\nstrain. Several approaches for differentiating the ferroelectric contribution\nfrom the EM response are also discussed. The review suggests a undamental\nguideline for the proper utilization of the PFM technique, as well as for\nachieving a reasonable interpretation of observed PFM responses."
    },
    {
        "anchor": "Intrinsic magnetism in monolayer transition metal trihalides: a\n  comparative study: Two dimensional magnetic materials, with tunable electronic properties could\nlead to new spintronic, magnetic and magneto-optic applications. Here, we\nexplore intrinsic magnetic ordering in two dimensional monolayers of transition\nmetal tri-halides (MX$_3$, M = V, Cr, Mn, Fe and Ni, and X = F, Cl, Br and I),\nusing density functional theory. We find that other than FeX$_3$ family which\nhas an anti-ferromagnetic ground state, rest of the trihalides are\nferromagnetic. Amongst these the VX$_3$ and NiX$_3$ family are found to have\nthe highest magnetic transition temperature, beyond the room temperature. In\nterms of electronic properties, the tri-halides of Mn and Ni are either half\nmetals or Dirac half metals, while the tri-halides of V, Fe and Cr are\ninsulators. Among all the trihalides studied in this paper, we find the\nexistence of very clean spin polarized Dirac half metallic state in MnF$_3$,\nMnCl$_3$, MnBr$_3$, NiF$_3$ and NiCl$_3$. These spin polarized Dirac half\nmetals will be immensely useful for spin-current generation and other\nspintronic applications.",
        "positive": "Screened Coulomb interactions in metallic alloys: II Screening beyond\n  the single-site and atomic sphere approximations: A quantitative description of the configurational part of the total energy of\nmetallic alloys with substantial atomic size difference cannot be achieved in\nthe atomic sphere approximation: It needs to be corrected at least for the\nmultipole moment interactions in the Madelung part of the one-electron\npotential and energy. In the case of a random alloy such interactions can be\naccounted for only by lifting the atomic sphere and single-site approximations,\nin order to include the polarization due to local environment effects.\nNevertheless a simple parameterization of the screened Coulomb interactions for\nthe ordinary single-site methods, including the generalized perturbation\nmethod, is still possible. We obtained such a parameterization for bulk and\nsurface NiPt alloys, which allows one to obtain quantitatively accurate\neffective interactions in this system."
    },
    {
        "anchor": "Electron and thermal transport via Variable Range Hopping in MoSe$_{2}$\n  single crystals: Bulk single crystal Molybdenum diselenide has been studied for its electronic\nand thermal transport properties. We perform resistivity measurements with\ncurrent in-plane (CIP) and current perpendicular to plane (CPP) as a function\nof temperature. The CIP measurements exhibit metal to semiconductor transition\nat $\\simeq 31$ K. In the semiconducting phase ($T > 31$ K), the transport is\nbest explained by variable range hopping (VRH) model. Large magnitude of\nresistivity in CPP mode indicates strong structural anisotropy. Seebeck\ncoefficient as a function of temperature measured in the range $90 - 300$ K,\nalso agrees well with the VRH model. The room temperature Seebeck coefficient\nis found to be $139$ $\\mu$V/K. VRH fittings of the resistivity and Seebeck\ncoefficient data indicate high degree of localization.",
        "positive": "Mechanical Properties of Pristine and Defective Carbon-Phosphide\n  Monolayers: A Density Functional Tight-Binding Study: Using density functional tight-binding theory, we investigated the elastic\nproperties and deformation and failure behaviors of pristine and defective\ncarbon-phosphide (CP) monolayers subjected to uniform uniaxial tensile strain\nalong armchair (AC) and zigzag (ZZ) directions. Two variants of carbon\nphosphide were studied and two types of carbon and phosphorous vacancies\n(single and double) were considered. It was found that carbon monovacancies\nhave the lowest formation energy, while phosphorous divacancies have the\nhighest one in both CP allotropes. A strong mechanical anisotropy for carbon\nphosphide was found with the Young\\'s modulus and the failure stress along ZZ\ndirection being an order of magnitude larger than those along AC direction. In\nboth allotropes, the Youngs modulus, failure stress and strain are considerably\naffected by vacancies, especially along AC direction. Fracture of pristine CP\nmonolayer occurred via the rupture of phosphorous-phosphorous bonds when CP\nmonolayer is stretched along AC direction, while via the rupture of\ncarbon-phosphorous bonds when stretched along ZZ direction. The failure strain\nand stress along the AC direction are affected only by phosphorous vacancies,\nwhile along the ZZ direction, they are almost equally affected by both\nphosphorous and carbon vacancies. These understandings may provide useful\nguidelines for potential applications of CP monolayers in nanoelectromechanical\nsystems."
    },
    {
        "anchor": "Anisotropic Magnetoresistance in Ga$_{1-x}$Mn$_x$As: We have measured the magnetoresistance in a series of Ga$_{1-x}$Mn$_x$As\nsamples with 0.033$\\le x \\le$ 0.053 for three mutually orthogonal orientations\nof the applied magnetic field. The spontaneous resistivity anisotropy (SRA) in\nthese materials is negative (i.e. the sample resistance is higher when its\nmagnetization is perpendicular to the measuring current than when the two are\nparallel) and has a magnitude on the order of 5% at temperatures near 10K and\nbelow. This stands in contrast to the results for most conventional magnetic\nmaterials where the SRA is considerably smaller in magnitude for those few\ncases in which a negative sign is observed. The magnitude of the SRA drops from\nits maximum at low temperatures to zero at T$_C$ in a manner that is consistent\nwith mean field theory. These results should provide a significant test for\nemerging theories of transport in this new class of materials.",
        "positive": "ScS_{2} Monolayer as a Potential Cathode Material for Alkali-ion\n  Batteries and Beyond: Sc is the lightest transition metal that could help to achieve the goal of\nhigh theoretical capacity. Hence, we here explored the performance of ScS_{2}\nmonolayer as a cathode material for alkali-ion batteries (Li, Na, K) and other\nmulti-valent metal-ion batteries (Mg, Al). Previous studies on ScS_{2} have\nfocused only on the fundamental electronic and magnetic properties of the\nScS_{2} monolayer, but not on its possible applications. Our first-principles\ncalculations show that 2D ScS_{2} is able to deliver a large theoretical\ncapacity of 491.36 mAh g^{-1} for alkali-ions and 324.29 mAh g^{-1} for Mg and\nAl-ions while maintaining good average open-circuit voltages. We also studied\nthe diffusivity of these metal ions on the ScS_{2} surface which is related to\nthe charge/discharge rate capability of batteries. Our results suggest low\ndiffusion barriers for all metal ions except Al. Owing to these results, we,\ntherefore, believe that the ScS_{2} monolayer can be an interesting candidate\nfor cathode material to be used in alkali-ion batteries and beyond."
    },
    {
        "anchor": "Atomistic simulations of amorphous polymers in the cloud with\n  PolymerModeler: Molecular dynamics (MD) simulations enable the description of ma- terial\nproperties and processes with atomistic detail by numerically solv- ing the\ntime evolution of every atom in the system. We introduce Poly- merModeler, a\ngeneral-purpose, online simulation tool to build atomistic structures of\namorphous polymers and perform MD simulations on the re- sulting configurations\nto predict their thermo-mechanical properties. Poly- merModeler is available,\nfree of charge, at nanoHUB.org via an interactive web interface, and the actual\nsimulations are performed in the cloud us- ing nanoHUB.org resources. Starting\nfrom the specification of one or more monomers PolymerModeler builds the\npolymer chains into a simulation cell with periodic boundary conditions at the\ndesired density. Monomers are added sequentially using the continuous\nconfiguration bias direct Monte Carlo method, and copolymers can be created\ndescribing the desired se- quence of monomers. PolymerModeler also enables\nusers to perform MD simulations on the structures created by the builder using\nthe Dreiding force field and Gasteiger partial atomic charges. We describe the\nforce field im- plementation and the various options for the MD simulations\nthat use the LAMMPS simulator. PolymerModeler MD simulations for a PMMA sam-\nple show good structural agreement with experiments and are in good agree- ment\nwith simulations obtained with commercial software.",
        "positive": "Control of magnetic relaxation by electric-field-induced ferroelectric\n  phase transition and inhomogeneous domain switching: Electric-field modulation of magnetism in strain-mediated multiferroic\nheterostructures is considered a promising scheme for enabling memory and\nmagnetic microwave devices with ultralow power consumption. However, it is not\nwell understood how electric-field-induced strain influences magnetic\nrelaxation, an important physical process for device applications. Here we\ninvestigate resonant magnetization dynamics in ferromagnet/ferrolectric\nmultiferroic heterostructures, FeGaB/PMN-PT and NiFe/PMN-PT, in two distinct\nstrain states provided by electric-field-induced ferroelectric phase\ntransition. The strain not only modifies magnetic anisotropy but also magnetic\nrelaxation. In FeGaB/PMN-PT, we observe a nearly two-fold change in intrinsic\nGilbert damping by electric field, which is attributed to strain-induced tuning\nof spin-orbit coupling. By contrast, a small but measurable change in extrinsic\nlinewidth broadening is attributed to inhomogeneous ferroelastic domain\nswitching during the phase transition of the PMN-PT substrate."
    },
    {
        "anchor": "Crystal structure of mixed fluorites Ca(1-x)Sr(x)F(2) and\n  Sr(1-x)Ba(x)F(2) and luminescence of Eu(2+) in the crystals: Within the framework of the virtual crystal method implemented in the shell\nmodel and pair potential approximation the crystal structure of mixed fluorites\nCa(1-x)Sr(x)F(2) and Sr(1-x)Ba(x)F(2) has been calculated. The impurity center\nEu(2+) and the distance Eu(2+)-F in this crystals have been also calculated.\nThe low level position of excited 4f65d configuration of the Eu(2+) ion has\nbeen expressed using phenomenological dependence on distance E(2+)-F. The\ndependences of Stokes shift and Huang-Rhys factor on concentration x have been\nreceived for yellow luminescence in Sr(1-x)Ba(x)F(2):Eu(2+). The value x, for\nwhich the eg -level of Eu(2+) ion will be in conduction band in\nSr(1-x)Ba(x)F(2):Eu(2+) has been calculated.",
        "positive": "Applied Machine Learning to Predict Stress Hotspots I: Face Centered\n  Cubic Materials: We investigate the formation of stress hotspots in polycrystalline materials\nunder uniaxial tensile deformation by integrating full field crystal plasticity\nbased deformation models and machine learning techniques to gain data driven\ninsights about microstructural properties. Synthetic 3D microstructures are\ncreated representing single phase equiaxed microstructures for generic copper\nalloys. Uniaxial tensile deformation is simulated using a 3-D full-field,\nimage-based Fast Fourier Transform (FFT) technique with rate-sensitive crystal\nplasticity, to get local micro- mechanical fields (stress and strain rates).\nStress hotspots are defined as the grains having stress values above the 90th\npercentile of the stress distribution. Hotspot neighborhoods are then\ncharacterized using metrics that reflect local crystallography, geometry, and\nconnectivity. This data is used to create input feature vectors to train a\nrandom forest learning algorithm, which predicts the grains that will become\nstress hotspots. We are able to achieve an area under the receiving operating\ncharacteristic curve (ROC-AUC) of 0.74 for face centered cubic materials\nmodeled on generic copper alloys. The results show the power and the\nlimitations of the machine learning approach applied to the polycrystalline\ngrain networks."
    },
    {
        "anchor": "The Quantum Nature in the Interaction of Molecular Hydrogen with Porous\n  Materials: Implications for Practical Hydrogen Storage: The storage of hydrogen (H$_2$) is of economic and ecological relevance,\nbecause it could potentially replace petroleum-based fuels. However, H$_2$\nstorage at mild condition remains one of the bottlenecks for its widespread\nusage. In order to devise successful H$_2$ storage strategies, there is a need\nfor a fundamental understanding of the weak and elusive hydrogen interactions\nat the quantum mechanical level. One of the most promising strategies for\nstorage at mild pressure and temperature is physisorption. Porous materials are\nspecially effective at physisorption, however the process at the quantum level\nhas been under-studied. Here, we present quantum calculations to study the\ninteraction of H$_2$ with building units of porous materials. We report 240\nH$_2$ complexes made of different transition metal (Tm) atoms, chelating\nligands, spins, oxidation states, and geometrical configurations. We found that\nboth the dispersion and electrostatics interactions are the major contributors\nto the interaction energy between H$_2$ and the transition metal complexes. The\nbinding energy for some of these complexes is in the range of at least 10\nkJ/mol for many interactions sites, which is one of these main requirements for\npractical H$_2$ storage. Thus, these results are of fundamental nature for\npractical H$_2$ storage in porous materials.",
        "positive": "Hyperfine Clock Transitions of Bismuth Donors in Silicon Detected by\n  Spin Dependent Recombination: Bismuth donors ion-implanted in $^{28}$Si and $^\\text{nat}$Si are studied\nusing magnetic resonance spectroscopy based on spin dependent recombination.\nThe hyperfine clock transition, at which the linewidth is significantly\nnarrowed, is observed for the bismuth donors. The experimental results are\nmodeled quantitatively by molecular orbital theory for a coupled pair\nconsisting of a bismuth donor and a spin dependent recombination readout\ncenter, including the effect of hyperfine and Zeeman interactions."
    },
    {
        "anchor": "Recent topics on metastability, hysteresis, avalanches, and acoustic\n  emission associated to martensitic transitions in functional materials: We review some results for the dynamics of first-order phase transitions in\nfunctional materials. We especially focus on simple models of athermal\nevolution in driven ferromagnets that give a global picture of metastability\nand hysteresis, showing that first-order phase transitions in such systems\nproceed by avalanches. Within this theoretical framework, we then discuss\nrecent experiments on acoustic emission avalanches in structural phase\ntransitions.",
        "positive": "Accurate structure factors from pseudopotential methods: Highly accurate experimental structure factors of silicon are available in\nthe literature, and these provide the ideal test for any \\emph{ab initio}\nmethod for the construction of the all-electron charge density. In a recent\npaper [J. R. Trail and D. M. Bird, Phys. Rev. B {\\bf 60}, 7863 (1999)] a method\nhas been developed for obtaining an accurate all-electron charge density from a\nfirst principles pseudopotential calculation by reconstructing the core region\nof an atom of choice. Here this method is applied to bulk silicon, and\nstructure factors are derived and compared with experimental and Full-potential\nLinear Augmented Plane Wave results (FLAPW). We also compare with the result of\nassuming the core region is spherically symmetric, and with the result of\nconstructing a charge density from the pseudo-valence density + frozen core\nelectrons. Neither of these approximations provide accurate charge densities.\nThe aspherical reconstruction is found to be as accurate as FLAPW results, and\nreproduces the residual error between the FLAPW and experimental results."
    },
    {
        "anchor": "Impact of disorder on the optoelectronic properties of\n  GaN$_y$As$_{1-x-y}$Bi$_x$ alloys and heterostructures: We perform a systematic theoretical analysis of the nature and importance of\nalloy disorder effects on the electronic and optical properties of\nGaN$_{y}$As$_{1-x-y}$Bi$_{x}$ alloys and quantum wells (QWs), using large-scale\natomistic supercell electronic structure calculations based on the\ntight-binding method. Using ordered alloy supercell calculations we also derive\nand parametrise an extended basis 14-band \\textbf{k}$\\cdot$\\textbf{p}\nHamiltonian for GaN$_{y}$As$_{1-x-y}$Bi$_{x}$. Comparison of the results of\nthese models highlights the role played by short-range alloy disorder --\nassociated with substitutional nitrogen (N) and bismuth (Bi) incorporation --\nin determining the details of the electronic and optical properties. Systematic\nanalysis of large alloy supercells reveals that the respective impact of N and\nBi on the band structure remain largely independent, a robust conclusion we\nfind to be valid even in the presence of significant alloy disorder where N and\nBi atoms share common Ga nearest neighbours. Our calculations reveal that N-\n(Bi-) related alloy disorder strongly influences the conduction (valence) band\nedge states, leading in QWs to strong carrier localisation, as well as\ninhomogeneous broadening and modification of the conventional selection rules\nfor optical transitions. Our analysis provides detailed insight into key\nproperties and trends in this unusual material system, and enables quantitative\nevaluation of the potential of GaN$_{y}$As$_{1-x-y}$Bi$_{x}$ alloys for\napplications in photonic and photovoltaic devices.",
        "positive": "Static and dynamic properties of ferroelectric thin film multilayers: A thermodynamic theory of ferroelectric thin film multilayers is developed.\nThe free energy function is written down using a multilayer model in which\nc-domain layers of one ferroelectric material alternate with a-domain layers of\na second ferroelectric material. We assume that the interfaces are perfectly\nsharp and that the polarization at these boundaries is zero. The\nrenormalization of the free energy coefficients due to the stresses in the\nfilms and to the depolarizing field was taken into account, as well as the\nrenormalization of the coefficients of the polarization gradients. The\nequilibrium inhomogeneous polarization temperature and its thickness dependence\nwere determined from the solutions of the Euler-Lagrange equations resulting\nfrom the minimization of the free energy functional. A thickness induced\nferroelectric phase transition is shown to exist and its transition temperature\nand critical layer thickness depend on the domain orientation. The criteria for\n''a/c'', ''c/c'' and ''a/a'' domain multilayering are calculated and expressed\nvia coefficients of the free energy density and the layer thickness.\n  The calculated multilayer susceptibility diverges at the transition\ntemperature of the thickness induced ferroelectric phase. This divergence is\nshown to be the origin of the giant dielectric response observed in some\nmultilayers. The theory gives an excellent fit to the temperature dependence of\nthe giant susceptibility observed recently in multilayers of\nPbTiO$_{3}$-Pb$_{1-x}$La$_{x}$TiO$_{3}$ ($x=0.28$)."
    },
    {
        "anchor": "Atomic mechanisms of self-diffusion in amorphous silicon: Based on recent calculations of the self-diffusion (SD) coefficient in\namorphous silicon (a-Si) by classical Molecular Dynamics simulation [M.\nPosselt, H. Bracht, and D. Radi\\'c, J. Appl. Phys. 131, 035102 (2022)] detailed\ninvestigations on atomic mechanisms are performed. For this purpose two\nStillinger-Weber-type potentials are employed, one strongly overestimates the\nSD coefficient, while the other leads to values much closer to the experimental\ndata. By taking into account the individual squared displacements (or diffusion\nlengths) of atoms the diffusional and vibrational contributions to the total\nmean squared displacement can be determined separately. It is shown that the\ndiffusional part is not directly correlated with the concentration of\ncoordination defects. The time-dependent distribution of squared displacements\nof atoms indicates that in a-Si a well-defined elemental diffusion length does\nnot exist, in contrast to SD in the crystalline Si. The analysis of atoms with\nlarge squared displacements reveals that the mechanisms of SD in a-Si are\ncharacterized by complex rearrangements of bonds or exchange of neighbors.\nThese are mono- and bi-directional exchanges of neighbors and neighbor\nreplacements. Exchanges or replacements may concern up to three neighbors and\nmay occur in relatively short periods of some ps. Bi- or mono-directional\nexchange or replacement of one neighbor atom happen more frequently than\nprocesses including more neighbors. A comparison of results for the two\ninteratomic potentials shows that an increased three-body parameter only slows\ndown the migration, but does not change the migration mechanisms fundamentally.",
        "positive": "Tunneling Anisotropic Spin Polarization in lateral (Ga,Mn)As/GaAs spin\n  Esaki diode devices: We report here on anisotropy of spin polarization obtained in lateral\nall-semiconductor all-electrical spin injection devices, employing\n$p^{+}-$(Ga,Mn)As/$n^{+}-$GaAs Esaki diode structures as spin aligning\ncontacts, resulting from the dependence of the efficiency of spin tunneling on\nthe orientation of spins with respect to different crystallographic directions.\nWe observed an in-plane anisotropy of $~8%$ in case of spins oriented either\nalong $[1\\bar{1}0]$ or $[110]$ directions and $~25%$ anisotropy between\nin-plane and perpendicular-to-plane orientation of spins."
    },
    {
        "anchor": "Magnetic stripe domain pinning and reduction of in plane magnet order\n  due to periodic defects in thin magnetic films: In thin magnetic films with strong perpendicular anisotropy and strong\ndemagnetizing field two ordered phases are possible. At low temperatures,\nperpendicularly oriented magnetic domains form a striped pattern. As\ntemperature is increased the system can undergo a spin reorientation transition\ninto a state with in-plane magnetization. Here we present Monte Carlo\nsimulations of such a magnetic film containing a periodic array of non-magnetic\ndefects. We find that the presence of defects stabilizes parallel orientation\nof stripes against thermal fluctuations at low temperatures. Above the spin\nreorientation temperature we find that defects favor perpendicular spin\nalignment and disrupt long range ordering of spin components parallel to the\nsample. This increases cone angle and reduces in plane correlations, leading to\na reduction in the spontaneous magnetization.",
        "positive": "The bright side of defects in MoS$_2$ and WS$_2$ and a generalizable\n  chemical treatment protocol for defect passivation: Structural defects are widely regarded as detrimental to the optoelectronic\nproperties of monolayer transition metal dichalcogenides, leading to concerted\nefforts to eliminate defects via improved materials growth or post-growth\npassivation. Here, using steady-state and ultrafast optical spectroscopy,\nsupported by ab initio calculations, we demonstrate that sulfur vacancy defects\nact as exciton traps. Current chemical treatments do not passivate these sites,\nleading to decreased mobility and trap-limited photoluminescence. We present a\ngeneralizable treatment protocol based on the use of passivating agents such as\nthiols or sulfides in combination with a Lewis acid to passivate sulfur\nvacancies in monolayer MoS$_2$ and WS$_2$, increasing photoluminescence up to\n275 fold, while maintaining mobilities. Our findings suggest a route for simple\nand rational defect engineering strategies, where the passivating agent varies\nthe electronic properties, thereby allowing the design of new heterostructures."
    },
    {
        "anchor": "Structure of long-period stacking/order Mg-Zn-RE (RE: rare-earth and Y)\n  phases with extended non-stoichiometry ranges: We propose structure models of the unique long-period stacking/order (LPSO)\nphases formed in the Mg-Zn-RE alloys, based on Z-contrast scanning transmission\nelectron microscopy (STEM) observations and first-principles calculations. The\nLPSO structures are long-period stacking derivatives of the hcp-Mg structure,\nand the Zn/RE distributions are restricted at the four close-packed atomic\nlayers forming local fcc-stacking (i.e., a local ABCA stacking). Chemical order\nis well developed for the LPSO phases formed in Mg97Zn1Er2 (14H-type) and\nMg85Zn6Y9 (18R-type) alloys with pronounced superlattice reflections, and the\nrelevant Zn/RE distributions are clearly emerged in the Z-contrast atomic\nimages. Initial ternary-ordered models are constructed by placing all the atoms\nat the ideal honeycomb sites, leading to plausible space groups of P63/mcm for\n14H-type and C2/m, P3112 or P3212 for 18R-type. Characteristic ordered feature\nis well represented by the local Zn6RE8 clusters, which are embedded in the\nfcc-stacking layers in accordance with the L12-type short-range order.\nEnergy-favored structural relaxations of the initial model cause significant\ndisplacements of the Zn/RE positions, implying that strong Zn-RE interactions\nmay play a critical role for the phase stability. The LPSO phases seem to\ntolerate a considerable degree of disorder at the Zn and RE sites with\nstatistical co-occupations by Mg, extending the non-stoichiometry phase region\nbounded along the Zn/RE equi-atomic line from ~Mg94.0Zn2.0Y4.0 to\n~Mg83.3Zn8.3Y8.3.",
        "positive": "Ultra-fast magnetization manipulation using single femtosecond light and\n  hot-electrons pulse: Current induced magnetization manipulation is a key issue for spintronic\napplication. Therefore, deterministic switching of the magnetization at the\npicoseconds timescale with a single electronic pulse represents a major step\ntowards the future developments of ultrafast spintronic. Here, we have studied\nthe ultrafast magnetization dynamics in engineered Gdx[FeCo]1-x based structure\nto compare the effect of femtosecond laser and hot-electrons pulses. We\ndemonstrate that a single femtosecond hot-electrons pulse allows a\ndeterministic magnetization reversal in either Gd-rich and FeCo-rich alloys\nsimilarly to a femtosecond laser pulse. In addition, we show that the limiting\nfactor of such manipulation for perpendicular magnetized films arises from the\nmulti-domain formation due to dipolar interaction. By performing time resolved\nmeasurements under various field, we demonstrate that the same magnetization\ndynamics is observed for both light and hot-electrons excitation and that the\nfull magnetization reversal take place within 5 ps. The energy efficiency of\nthe ultra-fast current induced magnetization manipulation is optimized thanks\nto the ballistic transport of hot-electrons before reaching the GdFeCo magnetic\nlayer."
    },
    {
        "anchor": "Fabrication of surface-patterned ZnO thin films using sol-gel methods\n  and nanoimprint lithography: Surface-patterned ZnO thin films were fabricated by direct imprinting on ZnO\nsol and subsequent annealing process. The polymer-based ZnO sols were deposited\non various substrates for the nanoimprint lithography and converted to\nsurface-patterned ZnO gel films during the thermal curing nanoimprint process.\nFinally, crystalline ZnO films were obtained by subsequent annealing of the\npatterned ZnO gel films. The optical characterization indicates that the\nsurface patterning of ZnO thin films can lead to an enhanced transmittance.\nLarge-scale ZnO thin films with different patterns can be fabricated by various\neasy-made ordered templates using this combination of sol-gel and nanoimprint\nlithography techniques.",
        "positive": "A Fourth-Generation High-Dimensional Neural Network Potential with\n  Accurate Electrostatics Including Non-local Charge Transfer: Machine learning potentials have become an important tool for atomistic\nsimulations in many fields, from chemistry via molecular biology to materials\nscience. Most of the established methods, however, rely on local properties and\nare thus unable to take global changes in the electronic structure into\naccount, which result from long-range charge transfer or different charge\nstates. In this work we overcome this limitation by introducing a\nfourth-generation high-dimensional neural network potential that combines a\ncharge equilibration scheme employing environment-dependent atomic\nelectronegativities with accurate atomic energies. The method, which is able to\ncorrectly describe global charge distributions in arbitrary systems, yields\nmuch improved energies and substantially extends the applicability of modern\nmachine learning potentials. This is demonstrated for a series of systems\nrepresenting typical scenarios in chemistry and materials science that are\nincorrectly described by current methods, while the fourth-generation neural\nnetwork potential is in excellent agreement with electronic structure\ncalculations."
    },
    {
        "anchor": "High thermoelectric performance in metallic NiAu alloys: Thermoelectric (TE) materials seamlessly convert thermal into electrical\nenergy and vice versa, making them promising for applications such as power\ngeneration or cooling. Although historically the TE effect was first discovered\nin metals, state-of-the-art research mainly focuses on doped semiconductors\nwith large figure of merit, $zT$, that determines the conversion efficiency of\nTE devices. While metallic alloys have superior functional properties, such as\nhigh ductility and mechanical strength, they have mostly been discarded from\ninvestigation in the past due to their small Seebeck effect. Here, we realize\nunprecedented TE performance in metals by tuning the energy-dependent\nelectronic scattering. Based on our theoretical predictions, we identify binary\nNiAu alloys as promising candidate materials and experimentally discover\ncolossal power factors up to 34 mWm$^{-1}$K$^{-2}$ (on average 30\nmWm$^{-1}$K$^{-2}$ from 300 to 1100 K), which is more than twice larger than in\nany known bulk material above room temperature. This system reaches a $zT$ up\nto 0.5, setting a new world record value for metals. NiAu alloys are not only\norders of magnitude more conductive than heavily doped semiconductors, but also\nhave large Seebeck coefficients originating from an inherently different\nphysical mechanism: within the Au s band conduction electrons are highly mobile\nwhile holes are scattered into more localized Ni d states, yielding a strongly\nenergy-dependent carrier mobility. Our work challenges the common belief that\ngood metals are bad thermoelectrics and presents an auspicious paradigm for\nachieving high TE performance in metallic alloys through engineering\nelectron-hole selective s-d scattering.",
        "positive": "Towards half-metallic interfaces: the Co$_2$CrAl/InP contacts: Although the interest on half-metallic Heusler alloys, susceptible to be used\nin spintronic applications, has considerably grown, their interfaces with\nsemiconductors show very low spin-polarization. I identify mechanisms which can\nkeep the high spin-polarization at the interface (more than 80% of the\nelectrons at the Fermi level are of majority spin) although the\nhalf-metallicity is lost. The large enhancement of the Cr moment at the\ninterface between a CrAl terminated Co$_2$CrAl(001) spacer and the InP(001)\nsemiconductor weakens the effect of the interface states resulting in this high\nspin-polarization. On the other hand the Co$_2$CrAl/InP interfaces made up by a\nCo layer and either an In or a P one show a severe decrease of the Co spin\nmoment but Cr in the subinterface layer is bulklike and the resulting\nspin-polarization is similar to the CrAl-based interfaces."
    },
    {
        "anchor": "A comprehensive study on the processing of Co:ZnO ceramics: defect\n  chemistry engineering and grain growth kinetics: In this report we present a systematic study on the preparation of Co:ZnO\nceramics via standard solid-state route from different Co precursors (Co3O4,\nCoO and metallic Co) and atmospheres (O2 and Ar). Particular emphasis was done\non the defect chemistry engineering and on the sintering growth kinetics.\nFirst-principles calculations based on density functional theory were employed\nto determine the formation energy of the main point defects in ZnO and Co:ZnO\nsystems. Based on the theoretical results a set of chemical reactions was\nproposed. A detailed microstructural characterization was performed in order to\ndetermine the degree of Co incorporation into the ZnO lattice. The samples\nprepared in Ar atmosphere and from metallic Co presents the highest Co\nsolubility limit (lower apparent Co incorporation activation energy) due to the\nincongruent ZnO decomposition. The determination of the parameters of the\nsintering growth kinetics reveals that Co3O4 is the best sintering additive in\norder to achieve higher densities in both sintering atmospheres. The results\ngive evidences that the sintering in O2 is effective in promoting zinc\nvacancies in the ZnO structure, while the sintering in Ar promotes zinc\ninterstitial defects. Our findings give valuable contribution to the\nunderstanding of the preparation of Co-doped ZnO ceramics and the sintering\ngrowth kinetics, what would allow to improve the state of the art on the\nprocessing of the material at both bulk and nanometric scales.",
        "positive": "Direct imaging of dopant and impurity distributions in 2D MoS$_2$: Molybdenum disulfide (MoS$_2$) nanosheet is a two-dimensional material with\nhigh electron mobility and with high potential for applications in catalysis\nand electronics. We synthesized MoS$_2$ nanosheets using a one-pot wet-chemical\nsynthesis route with and without Re-doping. Atom probe tomography revealed that\n3.8 at.% Re is homogeneously distributed within the Re-doped sheets. Other\nimpurities are found also integrated within the material: light elements\nincluding C, N, O, and Na, locally enriched up to 0.1 at.%, as well as heavy\nelements such as V and W. Analysis of the non-doped sample reveals that the W\nand V likely originate from the Mo precursor."
    },
    {
        "anchor": "Tunable Band Alignment with Unperturbed Carrier Mobility of On-Surface\n  Synthesized Organic Semiconducting Wires: The tunable properties of molecular materials place them among the favorites\nfor a variety of future generation devices. In addition, to maintain the\ncurrent trend of miniaturization of those devices, a departure from the present\ntop-down production methods may soon be required and self-assembly appears\namong the most promising alternatives. On-surface synthesis unites the promises\nof molecular materials and of self-assembly, with the sturdiness of covalently\nbonded structures: an ideal scenario for future applications. Following this\nidea, we report the synthesis of functional extended nanowires by\nself-assembly. In particular, the products correspond to one-dimensional\norganic semiconductors. The uniaxial alignment provided by our substrate\ntemplates allows us to access with exquisite detail their electronic\nproperties, including the full valence band dispersion, by combining local\nprobes with spatial averaging techniques. We show how, by selectively doping\nthe molecular precursors, the product's energy level alignment can be tuned\nwithout compromising the charge carrier's mobility.",
        "positive": "Energy-composition relations in Ni$_3$(Al$_{1-x}$X$_x$) phases: The secondary phase, such as Ni$_3$Al-based $L1_2$ $\\gamma^\\prime$, is\ncrucially important for precipitation strengthening of superalloys.\nComposition-structure-property relations provide useful insights for guided\nalloy design. Here we use density functional theory combined with the multiple\nscattering theory to compute dependencies of the structural energies and\nequilibrium volumes versus composition for ternary Ni$_3$(Al$_{1-x}$X$_x$)\nalloys with X=(Ti, Zr, Hf; V, Nb, Ta; Cr, Mo, W) in $L1_2$, $D0_{24}$, and\n$D0_{19}$ phases with a homogeneous chemical disorder on the (Al$_{1-x}$X$_x$)\nsublattice. Our results provide a better understanding of the physics in\nNi$_3$Al-based precipitates and facilitate design of next-generation nickel\nsuperalloys with precipitation strengthening."
    },
    {
        "anchor": "AC conductivity of polymer composites: an efficient confirmatory tool\n  for qualifying crude multi-walled carbon nanotube-samples: The present communication highlights that ac conductivity measurement of the\nmulti-walled carbon nanotubes (MWNTs)-polymer composites is a very promising\ncharacterizing tool for qualifying any crude MWNT-sample synthesized by\nelectric arc. It distinguishes graphite structures from that of the MWNTs and\nreflects the relative amount of nearly one-dimensional structures and disorders\npresent within the samples. This new protocol would help in evolving more\ndirect and quantitative criteria for qualification of MWNTs synthesized through\ndiverse techniques and will definitely add up to the conceptual understanding\nin visualizing the exact roles of different controlling parameters affecting\nthe growth of MWNTs.",
        "positive": "Coupling photogeneration with thermodynamic modeling of light-induced\n  alloy segregation enables the discovery of stabilizing dopants: We developed a generalized model that considers light as energy contributed\nthrough the thermalization of excited carriers to generate\nexcitation-intensity- and temperature-dependent phase diagrams. We find that\nthe model replicates the light-induced phase segregation behavior of the\nMAPb(I,Br)3 system. From there, we sought to study how best to design new,\nstable, mixed-halide alloys. The resultant first-principles predictions show\nthat the pseudo halide anion BF4- suppresses phase segregation in\nFA0.83Cs0.17Pb(I0.6Br0.4)3, resulting in enhanced operating stability. The\nfindings reveal that photostability is linked with the structure and electronic\nproperties of materials and may be overcome using informed alloying strategies."
    },
    {
        "anchor": "Theory and Ab Initio Computation of the Anisotropic Light Emission in\n  Monolayer Transition Metal Dichalcogenides: Monolayer transition metal dichalcogenides (TMDCs) are direct gap\nsemiconductors with unique potential for ultrathin light emitters. Yet, their\nphotoluminescence (PL) is not completely understood. We compute the radiative\nrecombination rate in monolayer TMDCs as a function of photon emission\ndirection and polarization, and obtain polar plots of the PL for different\nexcitation scenarios using the ab initio Bethe-Salpeter equation. We show that\nexcitons in a quantum superposition state of the K and K' inequivalent valleys\nemit light anisotropically upon recombination. Our results can explain the PL\nanisotropy and polarization dependence measured in recent experiments, and\npredict new light emission regimes. When averaged over emission angle and\nexciton momentum, our new treatment recovers the temperature dependent\nradiative lifetimes we previously derived. Our work provides a first-principles\napproach to study light emission in two-dimensional materials.",
        "positive": "Ab initio Studies of the Possible Magnetism in BN Sheet by Non-magnetic\n  Impurities and Vacancies: We performed first-principles calculations to investigate the possible\nmagnetism induced by the different concentrations of non-magnetic impurities\nand vacancies in BN sheet. The atoms of Be, B, C, N, O, Al and Si are used to\nreplace either B or N in the systems as impurities. We discussed the changes in\ndensity of states as well as the extent of the spatial distributions of the\ndefect states, the possible formation of magnetic moments, the magnitude of the\nmagnetization energies and finally the exchange energies due to the presence of\nthese defects. It is shown that the magnetization energies tend to increase as\nthe concentrations of the defects decreases in most of the defect systems which\nimplies a definite preference of finite magnetic moments. The calculated\nexchange energies are in general tiny but not completely insignificant for two\nof the studied defect systems, i.e. one with O impurities for N and the other\nwith B vacancies."
    },
    {
        "anchor": "Electric and thermoelectric transport in graphene and helical metal in\n  finite magnetic fields: We study electrical and thermoelectric transport properties of the surface\nstate of the topological insulator and graphene in the presence of randomly\ndistributed impurities. For finite impurity strength, the dependence of the\ntransport coefficients as a function of gate voltage, magnetic field and\nimpurity potential, are obtained numerically. In the limit of zero impurities\n(clean limit), analytic results for the peak values of the magneto-oscillations\nin thermopower are derived. Analogous with the conventional two dimensional\nelectron gas, the peak values are universal in the clean limit. Unlike\ngraphene, in topological insulators the coupling of the electron spin to its\nmomentum leads to a dependence of the transport coefficients on the\ngyromagnetic ratio ($g$). We compare our results with data on graphene and\nidentify unique signatures expected in topological insulators due to the\nmagnetoelectric coupling.",
        "positive": "Comment on \" Low-Lying Quasiparticle States and Hidden Collective Charge\n  Instabilities in Parent Cobaltate Superconductors\": Qian et al [1] recently reported angular-resolved photoemission spectroscopy\n(ARPES) measurements for Na0.8CoO2 that show two concentric Fermi surfaces (FS)\nsplit by a delta k_F that varies by a factor of three around the Brillouin zone\n(BZ). The surfaces occupy 70+/-5% of the full 2D BZ and were interpreted as the\nbonding and antibonding splitting (BAS) of the a1g bands, with an unspecified\neffect of magnetic ordering. Below we show that this interpretation is not\npossible, and, in fact, no valid intepretation of the observed spectra in terms\nof the bulk electronic structure of Na0.8CoO2 can be found."
    },
    {
        "anchor": "The transformation matrices (distortion, orientation, correspondence),\n  their continuous forms, and their variants: The crystallography of displacive phase transformations can be described with\nthree types of matrices: the lattice distortion matrix, the orientation\nrelationship matrix, and the correspondence matrix. The paper gives some\nformula to express them in crystallographic bases, orthonormal bases, and\nreciprocal bases, and it explains how to use them to deduce the matrices of\ninverse transformation. In the case of hard-sphere assumption, a continuous\nform of the distortion matrix can be determined, and its derivative is\nidentified to the velocity gradient used in continuum mechanics. The\ndistortion, the orientation and the correspondence variants are determined by\ncoset decomposition with intersection groups that depend on the point groups of\nthe phases and on the type of transformation matrix. The stretch variants\nrequired in the phenomenological theory of martensitic transformation should be\ndistinguished from the correspondence variants. The orientation variants and\nthe correspondence variants are also different; they are defined from the\ngeometric symmetries and algebraic symmetries, respectively. The concept of\norientation (ir)reversibility during thermal cycling is briefly and partially\ntreated by generalizing the orientation variants with n-cosets and graphs. Some\nsimple examples are given to show that there is no general relation between the\nnumbers of distortion, orientation and correspondence variants, and to\nillustrate the concept of orientation variants formed by thermal cycling.",
        "positive": "A Tight-Binding Grand Canonical Monte Carlo Study of the Catalytic\n  Growth of Carbon Nanotubes: The nucleation of carbon nanotubes on small nickel clusters is studied using\na tight binding model coupled to grand canonical Monte Carlo simulations. This\ntechnique closely follows the conditions of the synthesis of carbon nanotubes\nby chemical vapor deposition. The possible formation of a carbon cap on the\ncatalyst particle is studied as a function of the carbon chemical potential,\nfor particles of different size, either crystalline or disordered. We show that\nthese parameters strongly influence the structure of the cap/particle interface\nwhich in turn will have a strong effect on the control of the structure of the\nnanotube. In particular, we discuss the presence of carbon on surface or in\nsubsurface layers."
    },
    {
        "anchor": "Chemical aging of large-scale randomly rough frictional contacts: It has been shown that contact aging due to chemical reactions in single\nasperity contacts can have a significant effect on friction. However, it is\ncurrently unknown how chemically-induced contact aging of friction depends on\nroughness that is typically encountered in macroscopic rough contacts. Here, we\ndevelop an approach that brings together a kinetic Monte Carlo model of\nchemical aging with a contact mechanics model of rough surfaces based on the\nboundary element method to determine the magnitude of chemical aging in\nsilica/silica contacts with random roughness. Our multi-scale model predicts\nthat chemical aging for randomly rough contacts has a logarithmic dependence on\ntime. It also shows that friction aging switches from a linear to a non-linear\ndependence on the applied load as the load increase. We discover that surface\nroughness affects the aging behavior primarily by modifying the real contact\narea and the local contact pressure, whereas the effect of contact morphology\nis relatively small. Our results demonstrate how understanding of chemical\naging can be translated from studies of single asperity contacts to macroscopic\nrough contacts.",
        "positive": "Modeling of Magnetic Properties of NiCl$_2$ Nanostripes, Nanotubes and\n  Fullerenes: We show that the magnetic properties of antiferromagnetic layered NiCl$_{2}$\ncan be altered under nano-sizing depending on dimensionality and morphology\ntype of the corresponding nano-forms. By means of Monte-Carlo simulations\nwithin classical Heisenberg model, the spin ordering, magnetic part of heat\ncapacity C$_{v}$ and N\\'eel temperatures T$_{N}$ for multi-walled NiCl$_{2}$\nnanotubes and a fullerene were calculated and analyzed in comparison with the\nbulk NiCl$_{2}$ and multilayered two-dimensional NiCl$_{2}$ crystals and\nnanostripes. We have found that the nano-structuring of NiCl$_{2}$ at the size\nreducing and at the formation of the closed structures can influence\npropitiously on the preservation of antiferromagnetic properties."
    },
    {
        "anchor": "Large electric-field induced strain in BiFeO3 ceramics: Large bipolar strain of up to 0.36% (peak-to-peak value) was measured in\nBiFeO3 ceramics at low frequency (0.1 Hz) and large amplitude (140 kV/cm) of\nthe driving field. This strain is comparable to that achievable in highly\nefficient Pb-based perovskite ceramics, such as Pb(Zr,Ti)O3 and\nPb(Mg,Nb)O3-PbTiO3. The strain showed a strong dependence on the field\nfrequency and is likely largely associated with domain switching involving\npredominantly non-180{\\deg} domain walls. In addition, rearrangement of charged\ndefects by applying electric field of low frequency depins these domain walls,\nresulting in a more efficient switching and, consequently, an increased\nresponse.",
        "positive": "Nucleation of Ge clusters at high temperatures on Ge/Si(001) wetting\n  layer: Difference in nucleation of Ge quantum dots during Ge deposition at low (<\n600C) and high (> 600C) temperatures on the Si(001) surface is studied by high\nresolution scanning tunneling microscopy. Two process resulting in appearance\nof {105}-faceted clusters on the Ge wetting layer have been observed at high\ntemperatures: Pyramids have been observed to nucleate via the previously\ndescribed formation of strictly determined structures, resembling blossoms,\ncomposed by 16 dimers grouped in pairs and chains of 4 dimes on tops of the\nwetting layer M x N patches, each on top of a separate single patch, just like\nit goes on at low temperatures; an alternative process consists in faceting of\nshapeless heaps of excess Ge atoms which arise in the vicinity of strong sinks\nof adatoms, such as pits or steps. The latter process has never been observed\nat low temperatures; it is typical only for the high-temperature deposition\nmode."
    },
    {
        "anchor": "Ionisation processes and laser induced periodic surface structures in\n  dielectrics with mid-infrared femtosecond laser pulses: Irradiation of solids with ultrashort pulses and laser processing in the\nmid-Infrared (mid-IR) spectral region is a yet predominantly unexplored field\nwith a large potential for a wide range of applications. In this work, laser\ndriven physical phenomena associated with processes following irradiation of\nfused silica (SiO2) with ultrashort laser pulses in the mid-IR region are\ninvestigated in detail. A multiscale modelling approach is performed that\ncorrelates conditions for formation of perpendicular or parallel to the laser\npolarisation low spatial frequency periodic surface structures for low and high\nintensity mid-IR pulses (not previously explored in dielectrics at those\nwavelengths), respectively. Results demonstrate a remarkable domination of\ntunneling effects in the photoionisation rate and a strong influence of impact\nionisation for long laser wavelengths. The methodology presented in this work\nis aimed to shed light on the fundamental mechanisms in a previously unexplored\nspectral area and allow a systematic novel surface engineering with strong\nmid-IR fields for advanced industrial laser applications.",
        "positive": "Effective mobility for sequential carrier transport in multiple quantum\n  well structures: We investigate a theoretical model for effective carrier mobility to\ncomprehensively describe the behavior of the perpendicular carrier transport\nacross multiple quantum well (MQW) structures under applied electric field. The\nanalytical expressions of effective mobilities for thermionic emission, direct\ntunneling, and thermally-assisted tunneling are derived based on the\nquasi-thermal equilibrium approximation and the semi-classical approach.\nEffective electron and hole mobilities in InGaAs/GaAsP MQWs predicted from our\nmodel are in good agreement with the experimental results obtained from the\ncarrier time-of-flight measurement near room temperature. With this concept,\nthe complicated carrier dynamics inside MQWs can be simplified to an effective\nmobility, an equivalent parameter which is more straightforward to handle and\ncan be easily incorporated in the conventional drift-diffusion model."
    },
    {
        "anchor": "Atomically Thin Optical Lenses and Gratings: Two-dimensional (2D) materials have emerged as promising candidates for\nminiaturized optoelectronic devices, due to their strong inelastic interactions\nwith light. On the other hand, a miniaturized optical system also requires\nstrong elastic light-matter interactions to control the flow of light. Here, we\nreport giant optical path length (OPL) from a single-layer molybdenum disulfide\n(MoS2), which is around one order of magnitude larger than that from a\nsingle-layer graphene. Using such giant OPL to engineer the phase front of\noptical beams, we demonstrated, to the best of our knowledge, the world's\nthinnest optical lens consisting of a few layers of MoS2 less than 6.3 nm\nthick. Moreover, we show that MoS2 has much better dielectric response than\ngood conductor (like gold) and other dielectric materials (like Si, SiO2 or\ngraphene). By taking advantage of the giant elastic scattering efficiency in\nultra-thin high-index 2D materials, we demonstrated high-efficiency gratings\nbased on a single- or few-layers of MoS2. The capability of manipulating the\nflow of light in 2D materials opens an exciting avenue towards unprecedented\nminiaturization of optical components and the integration of advanced optical\nfunctionalities.",
        "positive": "Localized vs. delocalized character of charge carriers in LaAlO3/ SrTiO3\n  superlattices: Understanding the nature of electrical conductivity, superconductivity and\nmagnetism between layers of oxides is of immense importance for the design of\nelectronic devices employing oxide heterostructures. We demonstrate that\nresonant inelastic X-ray scattering can be applied to directly probe the\ncarriers in oxide heterostructures. Our investigation on epitaxially grown\nLaAlO3/SrTiO3 superlattices unambiguously reveals the presence of both\nlocalized and delocalized Ti 3d carriers. These two types of carriers are\ncaused by oxygen vacancies and electron transfer due to the polar discontinuity\nat the interface. This result allows explaining the reported discrepancy\nbetween theoretically calculated and experimentally measured carrier density\nvalues in LaAlO3/SrTiO3 heterostructures."
    },
    {
        "anchor": "Giant anisotropic nonlinear optical response in transition metal\n  monopnictide Weyl semimetals: Although Weyl fermions have proven elusive in high-energy physics, their\nexistence as emergent quasiparticles has been predicted in certain crystalline\nsolids in which either inversion or time-reversal symmetry is\nbroken\\cite{WanPRB2011,BurkovPRL2011, WengPRX2015,HuangNatComm2015}. Recently\nthey have been observed in transition metal monopnictides (TMMPs) such as TaAs,\na class of noncentrosymmetric materials that heretofore received only limited\nattention \\cite{XuScience2015, LvPRX2015, YangNatPhys2015}. The question that\narises now is whether these materials will exhibit novel, enhanced, or\ntechnologically applicable electronic properties. The TMMPs are polar metals, a\nrare subset of inversion-breaking crystals that would allow spontaneous\npolarization, were it not screened by conduction electrons\n\\cite{anderson1965symmetry,shi2013ferroelectric,kim2016polar}. Despite the\nabsence of spontaneous polarization, polar metals can exhibit other signatures\nof inversion-symmetry breaking, most notably second-order nonlinear optical\npolarizability, $\\chi^{(2)}$, leading to phenomena such as optical\nrectification and second-harmonic generation (SHG). Here we report measurements\nof SHG that reveal a giant, anisotropic $\\chi^{(2)}$ in the TMMPs TaAs, TaP,\nand NbAs. With the fundamental and second harmonic fields oriented parallel to\nthe polar axis, the value of $\\chi^{(2)}$ is larger by almost one order of\nmagnitude than its value in the archetypal electro-optic materials GaAs\n\\cite{bergfeld2003second} and ZnTe \\cite{wagner1998dispersion}, and in fact\nlarger than reported in any crystal to date.",
        "positive": "Interpreting X-ray absorption spectra of Vanadyl Phthalocyanines Spin\n  Qubit Candidates using a Machine Learning-Assisted Approach: The magnetic dilution of Vanadyl phthalocyanine (VOPc) within the\nisostructural diamagnetic Titanyl phthalocyanine (TiOPc) affords promising\nmolecular spin qubit platforms for solid-state quantum computing. The\ndevelopment of quantitative methods for determining how the interactions with a\nsupporting substrate impact the electronic structure of the system are\nfundamental to determine their potential integration in physical devices. In\nthis work we propose a combined approach based on X-ray absorption spectroscopy\n(XAS), atomic multiplet calculations, and density functional theory (DFT) to\ninvestigate the 3d orbital level structure of VOPc on TiOPc/Ag(100). We\ncharacterize VOPc in different molecular environments realized by changing the\nthickness of TiOPc interlayer and adsorption configuration on Ag(100).\nDepending on the molecular film structure, we find characteristic XAS features\nthat we analyze using atomic multiplet calculations. We use a Bayesian\noptimization algorithm to accelerate the parameter search process in the\nmultiplet calculations and identify the ground state properties, such as the 3d\norbital occupancy and splitting, as well as intra-atomic interactions. Our\nanalysis indicates that VOPc retains its spin S = 1/2 character in all\nconfigurations. Conversely, the energy separation and sequence of the\nunoccupied V 3d orbitals sensitively depend on the interaction with the surface\nand TiOPc interlayer. We validate the atomic orbital picture obtained from the\nmultiplet model by comparison with DFT, which further allows us to understand\nthe VOPc electronic properties using a molecular orbital description."
    },
    {
        "anchor": "Computational Search for Magnetic and Non-magnetic 2D Topological\n  Materials using Unified Spin-orbit Spillage Screening: Two-dimensional topological materials (TMs) have a variety of properties that\nmake them attractive for applications including spintronics and quantum\ncomputation. However, there are only a few such experimentally known materials.\nTo help discover new 2D TMs, we develop a unified and computationally\ninexpensive approach to identify magnetic and non-magnetic 2D TMs, including\ngapped and semi-metallic topological classifications, in a high-throughput way\nusing density functional theory-based spin-orbit spillage,\nWannier-interpolation, and related techniques. We first compute the spin-orbit\nspillage for the ~1000 2D materials in the JARVIS-DFT dataset\n(https://www.ctcms.nist.gov/~knc6/JVASP.html ), resulting in 122 materials with\nhigh-spillage values. Then, we use Wannier-interpolation to carry-out Z2,\nChern-number, anomalous Hall conductivity, Curie temperature, and edge state\ncalculations to further support the predictions. We identify various\ntopologically non-trivial classes such as quantum spin-hall insulators (QSHI),\nquantum anomalous-hall insulators (QAHI), and semimetals. For a few predicted\nmaterials, we run G0W0+SOC and DFT+U calculations. We find that as we introduce\nmany-body effects, only a few materials retain non-trivial band-topology,\nsuggesting the importance of high-level DFT methods in predicting 2D\ntopological materials. However, as an initial step, the automated spillage\nscreening and Wannier-approach provide useful predictions for finding new\ntopological materials and to narrow down candidates for experimental synthesis\nand characterization.",
        "positive": "Bioinspired approaches to toughen calcium phosphate-based ceramics for\n  bone repair: To respond to the increasing need for bone repair strategies, various types\nof biomaterials have been developed. Among those, calcium phosphate ceramics\n(CPCs) are promising since they possess a chemical composition similar to that\nof bones. To be suitable for implants, CPCs need to fulfill a number of\nbiological and mechanical requirements. Fatigue resistance and toughness are\ntwo key mechanical properties that are still challenging to obtain in CPCs.\nThis paper thus reviews and discusses current progress in the processing of\nCPCs with bioinspired microstructures for load-bearing applications. First,\nmethods to obtain CPCs with bioinspired structure at individual lengthscales,\nnamely nano-, micro-, and macroscale are discussed. Then, approaches to attain\nsynergetic contribution of all lengthscales through a complex and biomimetic\nhierarchical structure are reviewed. The processing methods and their design\ncapabilities are presented and the mechanical properties of the materials they\ncan produce are analysed. Their limitations and challenges are finally\ndiscussed to suggest new directions for the fabrication of biomimetic bone\nimplants with satisfactory properties. The paper could help biomedical\nresearchers, materials scientists and engineers to join forces to create the\nnext generation of bone implants."
    },
    {
        "anchor": "Dynamic disorder, phonon lifetimes, and the assignment of modes to the\n  vibrational spectra of methylammonium lead halide perovskites: We present Raman and terahertz absorbance spectra of methylammonium lead\nhalide single crystals (MAPbX3, X = I, Br, Cl) at temperatures between 80 and\n370 K. These results show good agreement with density-functional-theory phonon\ncalculations.1 Comparison of experimental spectra and calculated vibrational\nmodes enables confident assignment of most of the vibrational features between\n50 and 3500 cm-1. Reorientation of the methylammonium cations, unlocked in\ntheir cavities at the orthorhombic-to-tetragonal phase transition, plays a key\nrole in shaping the vibrational spectra of the different compounds.\nCalculations show that these dynamics effects split Raman peaks and create more\nstructure than predicted from the independent harmonic modes. This explains the\npresence of extra peaks in the experimental spectra that have been a source of\nconfusion in earlier studies. We discuss singular features, in particular the\ntorsional vibration of the C-N axis, which is the only molecular mode that is\nstrongly influenced by the size of the lattice. From analysis of the spectral\nlinewidths, we find that MAPbI3 shows exceptionally short phonon lifetimes,\nwhich can be linked to low lattice thermal conductivity. We show that optical\nrather than acoustic phonon scattering is likely to prevail at room temperature\nin these materials.",
        "positive": "Density functional description of long-range electron Coulomb\n  interactions in bulk SnS: A high-throughput benchmarking technique for testing the performance of\ndifferent exchange-correlation functionals and pseudopotentials is proposed and\napplied to bulk SnS. It is shown that, contrary to the popular view that the\nlocal density approximation can best describe layered materials, a semilocal\npseudopotential with a functional having a gradient dependence better described\nlattice vectors and `tetragonicity' of the lattice. We classify the\npseudopotentials based on this value and show that the participation ratio of\nmaximally localized Wannier functions follows the theory which states that more\ndistorted structures have higher anti-bonding hybridization as stabilizing\nfactor. In order to classify pseudopotentials, the local and nonlocal potential\ncontributions to the dynamical Born effective charges are taken for each\npseudopotential. Finally, a strategy is proposed for learning\nexchange-correlation functionals based on the distinction between short and\nlong range parts of the Kohn-Sham potential."
    },
    {
        "anchor": "Quantum spin Hall effect in monolayer and bilayer TaIrTe$_{4}$: Generally, stacking two quantum spin Hall insulators gives rise to a trivial\ninsulator. Here, based on first-principles electronic structure calculations,\nwe confirm that monolayer TaIrTe$_{4}$ is a quantum spin Hall insulator and\nremarkably find that bilayer TaIrTe$_{4}$ is still a quantum spin Hall\ninsulator. Theoretical analysis indicates that the covalent-like interlayer\ninteraction in combination with the small bandgap at time-reversal invariant\n$\\Gamma$ point results in new band inversion in bilayer TaIrTe$_{4}$, namely,\nthe emergence of quantum spin Hall phase. Meanwhile, a topological phase\ntransition can be observed by increasing the interlayer distance in bilayer\nTaIrTe$_{4}$. Considering that bulk TaIrTe$_{4}$ is a type-II Weyl semimetal,\nlayered TaIrTe$_{4}$ thus provides an ideal platform to realize different\ntopological phases at different dimensions.",
        "positive": "Transport in Magnetic Nanoparticles Super-Lattices : Coulomb Blockade,\n  Hysteresis and Magnetic Field Induced Switching: We report on magnetotransport measurements on millimetric super-lattices of\nCo-Fe nanoparticles surrounded by an organic layer. At low temperature, the\ntransition between the Coulomb blockade and the conductive regime becomes\nabrupt and hysteretic. The transition between both regime can be induced by a\nmagnetic field, leading to a novel mechanism of magnetoresistance. Between 1.8\nand 10 K, high-field magnetoresistance due to magnetic disorder at the surface\nof the particles is also observed. Below 1.8 K, this magnetoresistance abruptly\ncollapses and a low-field magnetoresistance is observed."
    },
    {
        "anchor": "Interference enhancement of Raman signal of graphene: Raman spectroscopic studies of graphene have attracted much interest. The\nG-band Raman intensity of a single layer graphene on Si substrate with 300 nm\nSiO2 capping layer is surprisingly strong and is comparable to that of bulk\ngraphite. To explain this Raman intensity anomaly, we show that in addition to\nthe interference due to multiple reflection of the incident laser, the multiple\nreflection of the Raman signal inside the graphene layer must be also accounted\nfor. Further studies of the role of SiO2 layer in the enhancement Raman signal\nof graphene are carried out and an enhancement factor of ~30 is achievable,\nwhich is very significant for the Raman studies. Finally, we discuss the\npotential application of this enhancement effect on other ultra-thin films and\nnanoflakes and a general selection criterion of capping layer and substrate is\ngiven.",
        "positive": "Bond analysis of cobalt and iron based skutterudites: elongated\n  lanthanum bonds in LaFe4P12: Motivated by the possibility of further improving the thermoelectric\nproperties of skutterudites we investigate charge transfer and bonding in this\nclass of materials using density functional calculations. Results for the CoP3,\nCoSb3, LaFe4P12 and the hypothetical FeP3 compounds are presented using the\nprocrystal as the non-binding reference. Spherical integration and Bader\nanalysis are performed to illustrate charge transfer differences between these\ncompounds. The results are in good qualitative agreement with simple\nelectronegativity considerations. The calculations confirm that the transition\nmetal-pnictogen and the pnictogen-pnictogen bonds are covalent, while the\nfiller atom-pnictogen bond is of a more polar and complex nature. The success\nof the \"rattling\" cage as phonon inhibitor is explained by a unique\nsemi-correlated bonding scheme between lanthanum and phosphorus. Elongated\nbonds along the crystal axes surrounds the lanthanum ion and generate a\ndodecahedra grid. Vibrations along the crystal axes are then closely connected\nto and scatter from the phosphorus rings. In the other directions, a more\nuncorrelated vibration is possible. This duality widens the phonon dampening\npossibilities."
    },
    {
        "anchor": "Hysteresis curves reveal the microscopic origin of cooperative CO$_2$\n  adsorption in diamine-appended metal-organic frameworks: Diamine-appended metal{organic frameworks (MOFs) of the form\nMg2(dobpdc)(diamine)2 adsorb CO2 in a cooperative fashion, exhibiting an abrupt\nchange in CO2 occupancy with pressure or temperature. This change is\naccompanied by hysteresis. While hysteresis is suggestive of a firstorder phase\ntransition, we show that hysteretic temperature-occupancy curves associated\nwith this material are qualitatively unlike the curves seen in the presence of\na phase transition; they are instead consistent with CO2 chain polymerization,\nwithin one-dimensional channels in the MOF, in the absence of a phase\ntransition. Our simulations of a microscopic model reproduce this dynamics, and\npoint the way toward rational control, in and out of equilibrium, of\ncooperative adsorption in this industrially important class of materials.",
        "positive": "Stability of Room Temperature Compensated Half-Metallicity in Cr-based\n  Inverse-Heusler Compounds: Using three correlated band approaches, namely the conventional band approach\nplus on-site Coulomb repulsion $U$, the modified Becke-Johnson functional, and\nhybrid functional, we have investigated inverse-Heusler ferrimagnets\nCr$_2$Co${\\cal Z}$ (${\\cal Z}$=Al, Ga, In). These approaches commonly indicate\nthat the Cr$_2$CoAl synthesized recently is a precise compensated half-metal\n(CHM), whereas Cr$_2$CoGa and Cr$_2$CoIn are ferrimagnets with a small moment.\nThis is also confirmed by the fixed spin moment approach. Analysis of the Bader\ncharge decomposition and the radial charge densities indicates that this\ncontrast is due to chemical differences among the ${\\cal Z}$ ions.\nAdditionally, in Cr$_2$CoAl, changing the volume by $\\pm$ 5% or the ratio of\n$c/a$ by $\\pm$ 2% does not alter the CHM state, suggesting that this state is\nrobust even under application of moderate pressure or strain. Considering the\nobserved high Curie temperature of 750 K, our results suggest that Cr$_2$CoAl\nis a promising candidate for robust high $T_C$ CHMs. Furthermore, the\nelectronic structure of the CHM Cr$_2$CoAl is discussed."
    },
    {
        "anchor": "Design of magnetic materials: Co$_2$Cr$_{1-x}$Fe$_{x}$Al: Doped Heusler compounds Co$_2$Cr$_{1-x}$Fe$_{x}$Al with varying Cr to Fe\nratio $x$ were investigated experimentally and theoretically. The electronic\nstructure of the ordered, doped Heusler compound Co$_2$Cr$_{1-x}$Fe$_{x}$Al\n($x=n/4, n=0,1,2,3,4)$ was calculated using different types of band structure\ncalculations. The ordered compounds turned out to be ferromagnetic with small\nAl magnetic moment being aligned anti-parallel to the 3d transition metal\nmoments. All compounds show a gap around the Fermi-energy in the minority\nbands. The pure compounds exhibit an indirect minority gap, whereas the\nordered, doped compounds exhibit a direct gap. Magnetic circular dichroism\n(MCD) in X-ray absorption spectra was measured at the $L_{2,3}$ edges of Co,\nFe, and Cr of the pure compounds and the $x=0.4$ alloy in order to determine\nelement specific magnetic moments. Calculations and measurements show an\nincrease of the magnetic moments with increasing iron content. The\nexperimentally observed reduction of the magnetic moment of Cr can be explained\nby Co-Cr site-disorder. The presence of the gap in the minority bands of\nCo$_2$CrAl can be attributed to the occurrence of pure Co$_2$ and mixed CrAl\n(001)-planes in the $L2_1$ structure. It is retained in structures with\ndifferent order of the CrAl planes but vanishes in the $X$-structure with\nalternating CoCr and CoAl planes.",
        "positive": "Optically controlling the competition between spin flips and intersite\n  spin transfer in a Heusler half-metal on sub-100 fs timescales: The direct manipulation of spins via light may provide a path toward\nultrafast energy-efficient devices. However, distinguishing the microscopic\nprocesses that can occur during ultrafast laser excitation in magnetic alloys\nis challenging. Here, we study the Heusler compound Co2MnGa, a material that\nexhibits very strong light-induced spin transfers across the entire M-edge. By\ncombining the element-specificity of extreme ultraviolet high harmonic probes\nwith time-dependent density functional theory, we disentangle the competition\nbetween three ultrafast light-induced processes that occur in Co2MnGa:\nsame-site Co-Co spin transfer, intersite Co-Mn spin transfer, and ultrafast\nspin-flips mediated by spin-orbit coupling. By measuring the dynamic magnetic\nasymmetry across the entire M-edges of the two magnetic sublattices involved,\nwe uncover the relative dominance of these processes at different probe energy\nregions and times during the laser pulse. Our combined approach enables a\ncomprehensive microscopic interpretation of laser-induced magnetization\ndynamics on timescales shorter than 100 fs."
    },
    {
        "anchor": "Rb-induced (3x1) and (6x1) reconstructions on Si(111)-(7x7): A LEED and\n  STM study: We present a study of the rubidium adsorption on the Si(111)-(7x7) surface\nand the related Rb-induced reconstructions as a function of deposition\ntemperature and Rb-coverage via scanning tunneling microscopy (STM) and\nlow-energy electron diffraction (LEED). Sample analysis via LEED allowed to\nobserve for the first time a Rb/Si(111)-(6x1) reconstruction. The STM image\nanalysis allowed to obtain the first real space characterization of the\nRb/Si(111)-(3x1) surface. In addition, STM provided a direct and local\ninformation on the surface arrangement as well as further insights on the\ninteraction between Si and Rb atoms and on the growth dynamics.",
        "positive": "Orbital magnetization and Chern number in a supercell framework: Single\n  k-point formula: The key formula for computing the orbital magnetization of a crystalline\nsystem has been recently found [D. Ceresoli, T. Thonhauser, D. Vanderbilt, R.\nResta, Phys. Rev. B {\\bf 74}, 024408 (2006)]: it is given in terms of a\nBrillouin-zone integral, which is discretized on a reciprocal-space mesh for\nnumerical implementation. We find here the single ${\\bf k}$-point limit, useful\nfor large enough supercells, and particularly in the framework of\nCar-Parrinello simulations for noncrystalline systems. We validate our formula\non the test case of a crystalline system, where the supercell is chosen as a\nlarge multiple of the elementary cell. We also show that--somewhat\ncounterintuitively--even the Chern number (in 2d) can be evaluated using a\nsingle Hamiltonian diagonalization."
    },
    {
        "anchor": "Theoretical Insights into C$-$H Bond Activation of Methane by Transition\n  Metal Clusters: The Role of Anharmonic Effects: Aiming towards materials design for methane activation, we study temperature\n($T$), pressure ($p$) dependence of the composition, structure, and stability\nof metal oxide clusters in a reactive atmosphere using a prototypical model\ncatalyst having wide applications: free transition metal (Ni) clusters in a\ncombined oxygen and methane atmosphere. A robust methodological approach is\nemployed, to show that the conventional harmonic approximation miserably fails\nfor this class of materials and capturing anharmonic effects to the vibration\nfree energy contribution is indispensable. To incorporate the anharmonicity in\nthe vibrational free energy, we evaluate the excess free energy of the clusters\nnumerically by thermodynamic integration method with hybrid density functional\ntheory and {\\em ab initio} molecular dynamics simulation inputs. We find that\nthe anharmonic effect has a significant impact in detecting the activation of\nC$-$H bond, whereas the harmonic infrared spectrum completely fails due to the\nwrong prediction of the vibrational modes.",
        "positive": "Configurational instability at the excited impurity ions in alkaline\n  earth fluorites: The formation of intrinsic defects by ionizing radiation in some ionic\ncrystals in the anion sublattice is only associated with the instability of the\nself-trapped exciton up to now. In this paper we propose a new mechanism for\nthe formation of the defects in the anion sublattice associated with the\nJanh-Teller instability occurring near the cation impurities in the excited\nstate. The instability occurs when the degenerate excited state of the impurity\nion is localized in the conduction band. We believe that the configuration\ninteraction between the discrete impurity level and host continuum (effect\nFano) plays an important role in this process."
    },
    {
        "anchor": "Trapping and Mobilization of Residual Fluid During Capillary\n  Desaturation in Porous Media: We discuss the problem of trapping and mobilization of nonwetting fluids\nduring immiscible two phase displacement processes in porous media. Capillary\ndesaturation curves give residual saturations as a function of capillary\nnumber. Interpreting capillary numbers as the ratio of viscous to capillary\nforces the breakpoint in experimental curves contradicts the theoretically\npredicted force balance. We show that replotting the data against a novel\nmacroscopic capillary number resolves the problem for discontinuous mode\ndisplacement.",
        "positive": "Novel highly conductive and transparent graphene based conductors: Future wearable electronics, displays and photovoltaic devices rely on highly\nconductive, transparent and yet mechanically flexible materials. Nowadays\nindium tin oxide (ITO) is the most wide spread transparent conductor in\noptoelectronic applications, however the mechanical rigidity of this material\nlimits its use for future flexible devices. Here we report novel transparent\nconductors based on few layer graphene (FLG) intercalated with ferric chloride\n(FeCl3) with an outstandingly high electrical conductivity and optical\ntransparency. We show that upon intercalation a record low sheet resistance of\n8.8 Ohm/square is attained together with an optical transmittance higher than\n84% in the visible range. These parameters outperform the best values of ITO\nand of other carbon-based materials, making these novel transparent conductors\nthe best candidates for future flexible optoelectronics."
    },
    {
        "anchor": "On the crystalline structure of orthorhombic SrRuO$_3$: A benchmark\n  study of DFT functionals: By investigating the crystalline structure of ground-state orthorhombic\nSrRuO$_3$, we present a benchmark study of some of the most popular density\nfunctional theory (DFT) approaches from the local density approximation (LDA),\ngeneralized-gradient approximation (GGA), and hybrid functional families.\nRecent experimental success in stabilizing tetragonal and monoclinic phases of\nSrRuO$_3$ at room temperature sheds a new light on the ability to accurately\ndescribe geometry of this material by applying first-principles calculations.\nTherefore, our work is aimed to analyse the performance of different DFT\nfunctionals and provide some recommendations for future research of SrRuO$_3$.\nA comparison of the obtained results to the low-temperature experimental data\nindicates that revised GGAs for solids are the best choice for the lattice\nconstants and volume due to their nice accuracy and low computational cost.\nHowever, when tilting and rotation angles appear on the scene, a combination of\nthe revised GGAs with the hybrid scheme becomes the most preferable option. It\nis important to note that a worse performance of LDA functional is somewhat\ncompensated by its realistic reproduction of electronic and magnetic structure\nof SrRuO$_3$, making it a strong competitor if the physical features are also\ntaken into account.",
        "positive": "A novel framework to model the fatigue behavior of brittle materials\n  based on a variational phase-field approach: A novel variational framework to model the fatigue behavior of brittle\nmaterials based on a phase-field approach to fracture is presented. The\nstandard regularized free energy functional is modified introducing a fatigue\ndegradation function that effectively reduces the fracture toughness as a\nproper history variable accumulates. This macroscopic approach allows to\nreproduce the main known features of fatigue crack growth in brittle materials.\nNumerical experiments show that the W\\\"ohler curve, the crack growth rate curve\nand the Paris law are naturally recovered, while the approximate Palmgren-Miner\ncriterion and the monotonic loading condition are obtained as special cases."
    },
    {
        "anchor": "Observation of oscillatory relaxation in the Sn-terminated surface of\n  epitaxial rock-salt SnSe $\\{111\\}$ topological crystalline insulator: Topological crystalline insulators have been recently predicted and observed\nin rock-salt structure SnSe $\\{111\\}$ thin films. Previous studies have\nsuggested that the Se-terminated surface of this thin film with hydrogen\npassivation, has a reduced surface energy and is thus a preferred\nconfiguration. In this paper, synchrotron-based angle-resolved photoemission\nspectroscopy, along with density functional theory calculations, are used to\ndemonstrate conclusively that a rock-salt SnSe $\\{111\\}$ thin film\nepitaxially-grown on \\ce{Bi2Se3} has a stable Sn-terminated surface. These\nobservations are supported by low energy electron diffraction (LEED)\nintensity-voltage measurements and dynamical LEED calculations, which further\nshow that the Sn-terminated SnSe $\\{111\\}$ thin film has undergone a surface\nstructural relaxation of the interlayer spacing between the Sn and Se atomic\nplanes. In sharp contrast to the Se-terminated counterpart, the observed Dirac\nsurface state in the Sn-terminated SnSe $\\{111\\}$ thin film is shown to yield a\nhigh Fermi velocity, $0.50\\times10^6$m/s, which suggests a potential mechanism\nof engineering the Dirac surface state of topological materials by tuning the\nsurface configuration.",
        "positive": "Structural properties of thin-film ferromagnetic topological insulators: We present a comprehensive study of the crystal structure of the thin-film,\nferromagnetic topological insulator (Bi, Sb)$_{2-x}$V$_x$Te$_3$. The\ndissipationless quantum anomalous Hall edge states it manifests are of\nparticular interest for spintronics, as a natural spin filter or pure spin\nsource, and as qubits for topological quantum computing. For ranges typically\nused in experiments, we investigate the effect of doping, substrate choice and\nfilm thickness on the (Bi, Sb)$_2$Te$_3$ unit cell using high-resolution X-ray\ndiffractometry. Scanning transmission electron microscopy and energy-dispersive\nX-ray spectroscopy measurements provide local structural and interfacial\ninformation. We find that the unit cell is unaffected in-plane by vanadium\ndoping changes, and remains unchanged over a thickness range of 4--10 quintuple\nlayers (1 QL $\\approx$ 1 nm). The in-plane lattice parameter ($a$) also remains\nthe same in films grown on different substrate materials. However, out-of-plane\nthe $c$-axis is reduced in films grown on less closely lattice-matched\nsubstrates, and increases with the doping level."
    },
    {
        "anchor": "Orthogonal spin arrangement as possible ground state of three -\n  dimensional Shastry - Sutherland network in Ba3Cu3In4O12: The Ba3Cu3In4O12 stands for unique topology of the magnetic subsystem. It\nconsists of rotated by 90\\Box$^b$ relative to each other \"paper-chain\" columns\nmade of vertex-sharing CuIO4 and CuIIO4 planar units. The overall pattern of\nthe copper ions is that of a three-dimensional Shastry-Sutherland network. At\nhigh temperatures, the magnetic susceptibility follows the Curie-Weiss law with\npositive Weiss temperature indicating strong predominance of ferromagnetic\ncoupling. At low temperatures, however, this compound reaches the\nantiferromagnetically ordered state and experiences non-trivial succession of\ntwo spin-flop and two spin-flip transitions reaching full saturation in modest\nmagnetic fields. Here we show that the possible ground state in Ba3Cu3In4O12\ncan be three-dimensional orthogonal arrangement of the Cu2+ (S = 1/2) magnetic\nmoments forming three virtually independent antiferromagnetic subsystems. In\nthis arrangement, favored by anisotropic exchange interactions, the quantum\nfluctuations provide the coupling between three mutually orthogonal magnetic\nsubsystems resulting in an impressive \"order by disorder\" effect.",
        "positive": "Structural stability and mechanism of compression of stoichiometric\n  B13C2 up to 68 GPa: Boron carbide is a ceramic material with unique properties widely used in\nnumerous, including armor, applications. Its mechanical properties, mechanism\nof compression, and limits of stability are of both scientific and practical\nvalue. Here, we report the behavior of the stoichiometric boron carbide B13C2\nstudied on single crystals up to 68 GPa. As revealed by synchrotron X-ray\ndiffraction, B13C2 maintains its crystal structure and does not undergo phase\ntransitions. Accurate measurements of the unit cell and B12 icosahedra volumes\nas a function of pressure led to conclusion that they reduce similarly upon\ncompression that is typical for covalently bonded solids. A comparison of the\ncompressional behavior of B13C2 with that of alpha-B, gamma-B, and B4C showed\nthat it is determined by the types of bonding involved in the course of\ncompression. Neither molecular-like nor inversed-molecular-like solid behavior\nupon compression was detected that closes a long-standing scientific dispute."
    },
    {
        "anchor": "A Note on Optimal Design of Multiphase Elastic Structures: The paper describes the first exact results in optimal design of three-phase\nelastic structures. Two isotropic materials, the \"strong\" and the \"weak\" one,\nare laid out with void in a given two-dimensional domain so that the compliance\nplus weight of a structure is minimized. As in the classical two-phase problem,\nthe optimal layout of three phases is also determined on two levels: macro- and\nmicroscopic. On the macrolevel, the design domain is divided into several\nsubdomains. Some are filled with pure phases, and others with their mixtures\n(composites). The main aim of the paper is to discuss the non-uniqueness of the\noptimal macroscopic multiphase distribution. This phenomenon does not occur in\nthe two-phase problem, and in the three-phase design it arises only when the\nmoduli of material isotropy of \"strong\" and \"weak\" phases are in certain\nrelation.",
        "positive": "Atomic-scale measurement of localized dislocation phonons at Si/Ge\n  interface: The nanoscale lattice imperfections, such as dislocations, have a significant\nimpact on the thermal transport properties in non-metallic materials.\nUnderstanding such effects requires the knowledge of defect phonon modes, which\nhowever is largely unexplored in experiments due to the challenge in\ncharacterization of phonons for the atomic-sized defects. Here, at the atomic\nscale we directly measure the localized phonon modes of dislocations at a Si/Ge\ninterface using scanning transmission electron microscopy electron energy loss\nspectroscopy. We find that the dislocation induces new phonon modes localized\nwithin ~2-unit cells of the core, which experience a redshift of several\nmilli-electron-volts compared to the dislocation-free case. The observed\nspectral features agree well with simulations. These localized modes are\nexpected to reduce the phonon transmission channels across the defect and thus\nthe local thermal conductivity. The revealed phonon modes localized at\ndislocations may help us to improve the thermal properties in thermoelectric\ngenerators and thermal management systems with proper defect engineering."
    },
    {
        "anchor": "Homogenisation of a Row of Dislocation Dipoles from Discrete Dislocation\n  Dynamics: Conventional discrete-to-continuum approaches have seen their limitation in\ndescribing the collective behaviour of the multi-polar configurations of\ndislocations, which are widely observed in crystalline materials. The reason is\nthat dislocation dipoles, which play an important role in determining the\nmechanical properties of crystals, often get smeared out when traditional\nhomogenisation methods are applied. To address such difficulties, the\ncollective behaviour of a row of dislocation dipoles is studied by using\nmatched asymptotic techniques. The discrete-to-continuum transition is\nfacilitated by introducing two field variables respectively describing the\ndislocation pair density potential and the dislocation pair width. It is found\nthat the dislocation pair width evolves much faster than the pair density. Such\nhierarchy in evolution time scales enables us to describe the dislocation\ndynamics at the coarse-grained level by an evolution equation for the slowly\nvarying variable (the pair density) coupled with an equilibrium equation for\nthe fast varying variable (the pair width). The time-scale separation method\nadopted here paves a way for properly incorporating dipole-like (zero net\nBurgers vector but non-vanishing) dislocation structures, known as the\nstatistically stored dislocations (SSDs) into macroscopic models of crystal\nplasticity in three dimensions. Moreover, the natural transition between\ndifferent equilibrium patterns found here may also shed light on understanding\nthe emergence of the persistent slip bands (PSBs) in fatigue metals induced by\ncyclic loads.",
        "positive": "Electrical and mechanical properties of a fully hydrogenated\n  two-dimensional polyaniline sheet: Two-dimensional (2D) polyaniline sheet has been recently synthesized and\nshowed that it is a semiconductor with indirect band gap. In this research, we\nexamine electrical and mechanical properties of a fully hydrogenated 2D\npolyaniline sheet C3NH using density functional theory. Results show that the\nC3NH sheet is an insulator with a band gap more than 5eV . The sheet is quasi\nplanner and dynamically stable confirmed by phonon band structure. Young\nmodulus of the sheet is 275N/m. Ab-initio molecular dynamics simulations show\nthat the C3NH sheet can be stable at 1000K indicating a high melting point.\nTensile strain reduces the band gap of the sheet and electron effective mass.\nIn return, hole effective mass is strongly dependent on the strain direction so\nthat strain along zigzag (armchair) increases (reduces) hole effective mass.\nour findings show that C3NH sheet is a promising candidate for electronic and\noptoelectronic applications and strain engineering can be used to tune its\nproperties."
    },
    {
        "anchor": "Deformation behaviour of body centered cubic Fe nanowires under tensile\n  and compressive loading: Molecular Dynamics (MD) simulations have been carried out to investigate the\ndeformation behaviour of <110>/{111} body centered cubic (BCC) Fe nanowires\nunder tensile and compressive loading. An embedded atom method (EAM) potential\nwas used to describe the interatomic interactions. The simulations were carried\nout at 10 K with a constant strain rate of $1\\times10^{8}$ $s^{-1}$. The\nresults indicate a significant differences in deformation mechanisms under\ntensile and compressive loading. Under tensile loading, the deformation occurs\nby the slip of full dislocations, While under compressive loading twinning was\nobserved as the dominant mode of deformation. The tension-compression asymmetry\nin deformation mechanisms of BCC Fe nanowires is attributed to\ntwinning-antitwinning asymmetry of 1/6<111> partial dislocation on {112}\nplanes. We further explain the mechanism of dislocation pile up in tensile\nloading and twin growth in compressive loading.",
        "positive": "Lithium Subhydrides Under Pressure and their Superatom-Like Building\n  Blocks: Evolutionary structure searches are used to predict a new class of compounds\nin the lithium--rich region of the lithium/hydrogen phase diagram under\npressure. First principles computations show that LimH, 4<m<9, are stabilized\nwith respect to LiH and Li between 50-100 GPa. The building block of all of the\nlithium subhydrides is an Li8H cluster, which can be thought of as a\nsuperalkali. The geometries and electronic structures of these phases is\nanalogous to that of the well-known alkali metal suboxides."
    },
    {
        "anchor": "Multi-Orbital Lattice Model for (Ga,Mn)As and Other Lightly Magnetically\n  Doped Zinc-Blende-Type Semiconductors: We present a Hamiltonian in real space which is well suited to study\nnumerically the behavior of holes introduced in III-V semiconductors by Mn\ndoping when the III$^{3+}$ ion is replaced by Mn$^{2+}$. We consider the actual\nlattice with the diamond structure. Since the focus is on light doping by\nacceptors, a bonding combination of III and V p-orbitals is considered since\nthe top of the valence band, located at the $\\Gamma$ point, has p character in\nthese materials. As a result, an effective model in which the holes hop between\nthe sites of an fcc lattice is obtained. We show that around the $\\Gamma$ point\nin momentum space the Hamiltonian for the undoped case is identical to the one\nfor the Luttinger-Kohn model. The spin-orbit interaction is included as well as\nthe on-site interaction between the spin of the magnetic impurity and the spin\nof the doped holes. The effect of Coulomb interactions between Mn$^{2+}$ and\nholes, as well as Mn$^{3+}$ doping are discussed. Through large-scale Monte\nCarlo simulations on a Cray XT3 supercomputer, we show that this model\nreproduces many experimental results for ${\\rm Ga_{\\it 1-x}Mn_{\\it x}As}$ and\n${\\rm Ga_{\\it 1-x}Mn_{\\it x}Sb}$, and that the Curie temperature does not\nincrease monotonically with $x$. The cases of Mn doped GaP and GaN, in which\nMn$^{3+}$ is believed to play a role, are also studied.",
        "positive": "Helium-Implantation-Induced Lattice Strains and Defects in Tungsten\n  probed by X-ray Micro-diffraction: Tungsten is the main candidate material for plasma-facing armour components\nin future fusion reactors. Bombardment with energetic fusion neutrons causes\ncollision cascade damage and defect formation. Interaction of defects with\nhelium, produced by transmutation and injected from the plasma, modifies defect\nretention and behaviour. Here we investigate the residual lattice strains\ncaused by different doses of helium-ion-implantation into tungsten and\ntungsten-rhenium alloys. Energy and depth-resolved synchrotron X-ray\nmicro-diffraction uniquely permits the measurement of lattice strain with\nsub-micron 3D spatial resolution and ~10-4 strain sensitivity. Increase of\nhelium dose from 300 appm to 3000 appm increases volumetric strain by only ~2.4\ntimes, indicating that defect retention per injected helium atom is ~3 times\nhigher at low helium doses. This suggests that defect retention is not a simple\nfunction of implanted helium dose, but strongly depends on material composition\nand presence of impurities. Conversely, analysis of W-1wt% Re alloy samples and\nof different crystal orientations shows that both the presence of rhenium, and\ncrystal orientation, have comparatively small effect on defect retention. These\ninsights are key for the design of armour components in future reactors where\nit will be essential to account for irradiation-induced dimensional change when\npredicting component lifetime and performance."
    },
    {
        "anchor": "Charged domain walls in BaTiO$_3$ crystals emerging from superdomain\n  boundaries: Previous experiments with BaTiO$_3$ single crystals have shown that\napplication of the electric field in the vicinity of the ferroelectric phase\ntransition can be used to introduce peculiar persisting ferroelectric domain\nwalls, accompanied by the compensating charge in the form of two-dimensional\nelectron gas. The present in-situ optical observations of such electric poling\nprocess reveal formation of a transient coexistence of the cubic and\nferroelectric phases, the latter one being broken into multiple martensitic\nsuperdomains, separated by superdomain walls. It is revealed that as the\ntransient superdomains convert into the regular ferroelectric domains, the\nsuperdomain boundaries transform into the desired charged domain walls. In\norder to assign the observed transient domain patterns, to understand the\nshapes of the observed ferrolectric precipitates and their agglomerates as well\nas to provide the overall interpretation of the observed domain formation\nprocess, the implications of the mechanical compatibility of the coexisting\nsuperdomain states is derived in the framework of the Wechsler-Lieberman-Read\ntheory. The results also suggest that the transport of the compensating charge\ncarriers towards the final charged domain wall location is directly associated\nwith the electric conductivity and interlinked motion and growth of the\nsuperdomain walls and phase fronts.",
        "positive": "Biaxial compression of centimeter scale graphene on strictly 2D\n  substrate: Biaxial compression of centimetre-scale graphene, freely standing on the\nsurface of water is studied. Within this platform, we report full stress-strain\ncompression of graphene identifying elastic and plastic deformations. The\nYoung's modulus follows a scaling law and falls two orders of magnitude below\nthe commonly reported values with microscale graphene samples. Such results\nstrongly confirm that graphene - in its very natural form - lacks any intrinsic\nelastic parameters. Different functionalization/manipulation of graphene\nlattice affects the mechanics of graphene differently; particularly the effect\nof the sp3 hybridization and crystalline voids on the yield strength of\ngraphene is explored. Crumpling of graphene is accompanied by gradual\ngeneration and transformation of wrinkles which brings about viscoelasticity in\ngraphene, observed for the first time in this paper. Additionally, we report a\npeculiar correlation between the morphology and the distribution of the strain\nin graphene lattice."
    },
    {
        "anchor": "Platinum/Yttrium Iron Garnet Inverted Structures for Spin Current\n  Transport: 30-80 nm thick yttrium iron garnet (YIG) films are grown by pulsed laser\ndeposition on a 5 nm thick sputtered Pt atop gadolinium gallium garnet\nsubstrate (GGG) (110). Upon post-growth rapid thermal annealing, single crystal\nYIG(110) emerges as if it were epitaxially grown on GGG(110) despite the\npresence of the intermediate Pt film. The YIG surface shows atomic steps with\nthe root-mean-square roughness of 0.12 nm on flat terraces. Both Pt/YIG and\nGGG/Pt interfaces are atomically sharp. The resulting YIG(110) films show clear\nin-plane uniaxial magnetic anisotropy with a well-defined easy axis along <001>\nand a peak-to-peak ferromagnetic resonance linewidth of 7.5 Oe at 9.32 GHz,\nsimilar to YIG epitaxilly grown on GGG. Both spin Hall magnetoresistance and\nlongitudinal spin Seebeck effects in the inverted bilayers indicate excellent\nPt/YIG interface quality.",
        "positive": "Crystal structure prediction at finite temperatures: Crystal structure prediction is a central problem of theoretical\ncrystallography and materials science, which until mid-2000s was considered\nintractable. Several methods, based on either energy landscape\nexploration$^{1,2}$ or, more commonly, global optimization$^{3-8}$, largely\nsolved this problem and enabled fully non-empirical computational materials\ndiscovery$^{9,10}$. A major shortcoming is that, to avoid expensive\ncalculations of the entropy, crystal structure prediction was done at zero\nKelvin and searched for the global minimum of the enthalpy, rather than free\nenergy. As a consequence, high-temperature phases (especially those which are\nnot quenchable to zero temperature) could be missed. Here we develop an\naccurate and affordable solution, enabling crystal structure prediction at\nfinite temperatures. Structure relaxation and fully anharmonic free energy\ncalculations are done by molecular dynamics with a force field (which can be\nanything from a parametric force field for simpler cases to a trained\non-the-fly machine learning interatomic potential), the errors of which are\ncorrected using thermodynamic perturbation theory to yield accurate ab initio\nresults. We test the accuracy of this method on metals (probing the P-T phase\ndiagram of Al and Fe), a refractory intermetallide (WB), and a significantly\nionic ceramic compound (Earth-forming silicate MgSiO3 at pressures and\ntemperatures of the Earth's lower mantle). We find that the hcp-phase of\naluminum has a wider stability field than previously thought, and the\ntemperature-induced transition $\\alpha$-$\\beta$ in WB occurs at 2789 K. It is\nalso found that iron has hcp structure at conditions of the Earth's inner core,\nand the much debated (and important for constraining Earth's thermal structure)\nClapeyron slope of the post-perovskite phase transition in MgSiO3 is 5.88\nMPa/K."
    },
    {
        "anchor": "Molecular beam epitaxy of single crystalline GaN nanowires on a flexible\n  Ti foil: We demonstrate the self-assembled growth of vertically aligned GaN nanowire\nensembles on a flexible Ti foil by plasma-assisted molecular beam epitaxy. The\nanalysis of single nanowires by transmission electron microscopy reveals that\nthey are single crystalline. Low-temperature photoluminescence spectroscopy\ndemonstrates that, in comparison to standard GaN nanowires grown on Si, the\nnanowires prepared on the Ti foil exhibit a equivalent crystalline perfection,\na higher density of basal-plane stacking faults, but a reduced density of\ninversion domain boundaries. The room-temperature photoluminescence spectrum of\nthe nanowire ensemble is not influenced or degraded by the bending of the\nsubstrate. The present results pave the way for the fabrication of flexible\noptoelectronic devices based on GaN nanowires on metal foils.",
        "positive": "Structure, microstructure and electrical properties of new lead-free\n  (1-x)(Li0.12Na0.88)NbO3-xBaTiO3 (0 to x to 40) piezoelectric ceramics: A new lead-free (1-x)Li0.12Na0.88NbO3-xBaTiO3 (0 to x to 40) piezoelectric\nceramics have been prepared using conventional ceramics processing route.\nStructural analysis revealed an existence of morphotropic phase boundary (MPB),\nseparating orthorhombic and tetragonal phases, between the BaTiO3 content, x =\n10-12.5. A partial phase diagram has been established based on\ntemperature-dependent permittivity data for this new system and a nearly\nvertical temperature-independent MPB is observed. An improvement in electrical\nproperties near MPB (e.g., for x = 12.5; {\\epsilon}r = 10489 at Tm, d33 = 30\npC/N, kp = 12.0 %, Qm = 162, Pr = 11.2 {\\mu}C/cm2, Ec = 19.2 kV/cm, d*33 = 269\npm/V) is observed and is attributed to the ease of polarization rotation due to\ncoexistence of orthorhombic and tetragonal phases. The results show that these\nmaterials could be suitable for piezoelectric vibrators and ultrasonic\ntransducers applications. The sample with x = 25, also shows high dielectric\npermittivity, {\\epsilon}r = 3060, and low dielectric loss, tan{\\delta} = 0.033\nwhich could be suitable for capacitor (X7R/Z5U) applications."
    },
    {
        "anchor": "Effect of Spin Fluctuations on Magnetoresistance and Anomalous Hall\n  Effect in the Chiral Magnet Co8Zn8Mn4: The beta Mn type Co-Zn-Mn alloys have seized significant attention due to\ntheir ability to host skyrmions at room temperature. Here we analyse the\nunconventional magneto-transport properties of Co8Zn8Mn4 single crystals with a\nCurie temperature of 275 K. A negative magnetoresistance is obtained over a\nwide temperature range of 50K to 300K. The deviation of the isothermal\nmagnetoresistance (MR) curves from linearity to non-linearity as one approaches\nhigher temperatures points towards the transition from the dominance of magnons\nto spin fluctuations. In the paramagnetic phase, the change in the shape of the\nMR curve has been explained using the Khosla and Fischer model. The\nrelationship between the anomalous Hall effect (AHE) and longitudinal\nresistivity reveals the dominance of the skew-scattering mechanism, which is\ninexplicable based on the theories of semi-classical magneto-transport. We\nexperimentally determine that the spin fluctuation is the source of the\nskew-scattering mechanism in Co8Zn8Mn4. In general skew-scattering mechanisms\npredominate in compounds with high conductivity, but our findings demonstrate\nthat this is not always the case and that other aspects also require equal\nconsideration. Our work throws new light on the predominant scattering\nmechanism in chiral magnets with skyrmionics phase at low conductivity.",
        "positive": "Doubled Quantum Spin Hall Effect with High-Spin Chern Number in\n  $\u03b1$-Antimonene and $\u03b1$-Bismuthene: The discovery of quantum spin Hall effect has ignited the field of\ntopological physics with vast variety of exotic properties. Here, we present\nthe emergence of doubled quantum spin Hall effect in two dimensions\ncharacterized with a high spin Chern number of ${\\mathcal C_S}=2$ and two pairs\nof helical edge states. Although is overlooked and invisible in topological\nquantum chemistry and symmetry indicator theory, the already experimentally\nsynthesized $\\alpha$-antimonene and $\\alpha$-bismuthene are revealed as\nrealistic material candidates of predicted topological states with band\ninversions emerging at generic $k$-points, rather than the high-symmetry\nmomenta. Remarkably, the nontrivial energy gap can be as large as 464 meV for\n$\\alpha$-bismuthene, indicating the high possibility of room-temperature\nobservation of the doubled quantum spin Hall effect. Moreover, a four-band\neffective model is constructed to demonstrate further the feasibility of\nattaining this type of nontrivial topology. Our results not only uncover a\nnovel topological character of antimony and bismuth, but will also facilitate\nthe experimental characterization of the previously overlooked hidden topology."
    },
    {
        "anchor": "Pressure enhanced thermoelectric properties in Mg2Sn: Pressure dependence of electronic structures and thermoelectric properties of\n$\\mathrm{Mg_2Sn}$ are investigated by using a modified Becke and Johnson (mBJ)\nexchange potential, including spin-orbit coupling (SOC). The corresponding\nvalue of spin-orbit splitting at $\\Gamma$ point is 0.47 eV, which is in good\nagreement with the experimental value 0.48 eV. With the pressure increasing,\nthe energy band gap first increases, and then decreases. In certain doping\nrange, the power factor for n-type has the same trend with energy band gap,\nwhen the pressure increases. Calculated results show that the pressure can lead\nto significantly enhanced power factor in n-type doping below the critical\npressure, and the corresponding lattice thermal conductivity near the critical\npressure shows the relatively small value. These results make us believe that\nthermoelectric properties of $\\mathrm{Mg_2Sn}$ can be improved in n-type doping\nby pressure.",
        "positive": "Revisiting the low temperature electron-phonon relaxation of noble\n  metals: The low temperature electron-phonon (e-ph) relaxation near the surface of\nnoble metals, Cu and Ag, is studied by using the density-functional theory\napproach. The appearance of the surface phonon mode can give rise to a strong\nenhancement of the Eliashberg function at low frequency $\\omega$. Assuming the\nEliashberg function proportional to the square of $\\omega$ in the low frequency\nlimit, the e-ph relaxation time obtained from the surface calculations is\nshorter than that from the bulk calculation. The calculated e-ph relaxation\ntime for the former is in agreement with a recent experiment for thin films."
    },
    {
        "anchor": "Control of carrier transport in GaAs by longitudinal-optical\n  phonon-carrier scattering using a pair of laser pump pulses: We demonstrate optical control of the LO phonon-plasmon coupled (LOPC) modes\nin GaAs by using a femtosecond pump-pulse pair. The relaxation time of the\nplasmon-like LOPC mode significantly depends on the separation time (\\Delta t)\nof the pump-pulse pair. Especially it is maximized when \\Delta t becomes\nsimultaneously comparable to the half period of the longitudinal optical (LO)\nphonon oscillation and resonant to the 3/4 period of the plasmon-like LOPC\noscillation. We attribute these observations to the modification of carrier-LO\nphonon scattering and ballistic motion of the plasmon-like LOPC mode.",
        "positive": "First Principles Studies of KNbO$_3$, KTaO$_3$ and LiTaO$_3$ Solid\n  Solutions: KTaO_3-based solid solutions exhibit a variety of interesting physical\nphenomena. To better understand these phenomena, we performed first-principles\ncalculations on [K_{1-x}, Li_x]TaO_3 (KLT) and K[Ta_{1-x}, Nb_x]O_3 (KTN)\nsupercells. Our results show Li displacements and potential barrier heights in\nKLT that are in excellent agreement with values obtained from experimental\nfits. Dramatic changes in B-site dynamical charges occur in KTN in response to\nchanges in near neighbor (nn) coordination. These effects can be explained by\nheterogeneity in the local electronic dielectric permittivity."
    },
    {
        "anchor": "Theoretical study of the thermoelectric properties of SiGe nanotubes: The thermoelectric properties of two typical SiGe nanotubes are investigated\nusing a combination of density functional theory, Boltzmann transport theory,\nand molecular dynamics simulations. Unlike carbon nanotubes, these SiGe\nnanotubes tend to have gear-like geometry, and both the (6, 6) and (10, 0)\ntubes are semiconducting with direct band gaps. The calculated Seebeck\ncoefficients as well as the relaxation time of these SiGe nanotubes are\nsignificantly larger than those of bulk thermoelectric materials. Together with\nsmaller lattice thermal conductivity caused by phonon boundary and alloy\nscattering, these SiGe nanotubes can exhibit very good thermoelectric\nperformance. Moreover, there are strong chirality and temperature dependence of\nthe ZT values, which can be optimized to 4.9 at room temperature and further\nenhanced to 5.4 at 400 K for the armchair (6, 6) tube.",
        "positive": "Red Luminescence in H-doped beta-Ga2O3: The effects of hydrogen incorporation into beta-Ga2O3 thin films have been\ninvestigated by chemical, electrical and optical characterization techniques.\nHydrogen incorporation was achieved by remote plasma doping without any\nstructural alterations of the film; however, X-ray photoemission reveals major\nchanges in the oxygen chemical environment. Depth-resolved cathodoluminescence\n(CL) reveals that the near-surface region of the H-doped Ga2O3 film exhibits a\ndistinct red luminescence (RL) band at 1.9 eV. The emergence of the H-related\nRL band is accompanied by an enhancement in the electrical conductivity of the\nfilm by an order of magnitude. Temperature-resolved CL points to the formation\nof abundant H-related donors with a binding energy of 28 +/- 4 meV. The RL\nemission is attributed to shallow donor-deep acceptor pair recombination, where\nthe acceptor is a VGa-H complex and the shallow donor is interstitial H. The\nbinding energy of the VGa-H complex, based on our experimental considerations,\nis consistent with the computational results by Varley et al [J. Phys.:\nCondens. Matter, 23, 334212, 2011]."
    },
    {
        "anchor": "Perfect and Stable Hybrid Glasses from Strong and Fragile Metal-Organic\n  Framework Liquids: Hybrid glasses connect emerging fields of metal-organic frameworks (MOFs)\nwith the glass-formation, amorphization, and melting processes of these\nstructurally diverse and chemically versatile systems. Most zeolites, including\nMOFs, amorphize around the glass transition, devitrifying and then melting at\nmuch higher temperatures. The relationship between the two processes has so far\nnot been investigated. Herein we show how heating first results in a low\ndensity perfect glass, following an order-order transition, leading to a\nsuper-strong liquid of low fragility that dynamically controls MOF collapse. A\nsubsequent order-disorder transition creates a high density liquid of greater\nfragility. After crystallization and melting, subsequent cooling results in a\nstable glass virtually identical to the high density phase. Furthermore, the\nwide-ranging melting temperatures of different MOFs suggest these can be\ndifferentiated by topology. Our research provides new insight into the\nstability and functionality of these novel ductile crystalline materials,\nincluding the possibility of melt-casting MOFs.",
        "positive": "A multicaloric material as a link between electrocaloric and\n  magnetocaloric refrigeration: The existence and feasibility of the multicaloric, polycrystalline material\n0.8Pb(Fe1/2Nb1/2)O3-0.2Pb(Mg1/2W1/2)O3, exhibiting magnetocaloric and\nelectrocaloric properties, are demonstrated. Both the electrocaloric and\nmagnetocaloric effects are observed over a broad temperature range below room\ntemperature. The maximum magnetocaloric temperature change of ~0.26 K is\nobtained with a magnetic-field amplitude of 70 kOe at a temperature of 5 K,\nwhile the maximum electrocaloric temperature change of ~0.25 K is obtained with\nan electric-field amplitude of 60 kV/cm at a temperature of 180 K. The material\nallows a multicaloric cooling mode or a separate caloric-modes operation\ndepending on the origin of the external field and the temperature at which the\nfield is applied."
    },
    {
        "anchor": "A minimalist approach to 3D photoemission orbital tomography: algorithms\n  and data requirements: Photoemission orbital tomography provides direct access from laboratory\nmeasurements to the real-space molecular orbitals of well-ordered organic\nsemiconductor layers. Specifically, the application of phase retrieval\nalgorithms to photon-energy- and angle-resolved photoemission data enables the\ndirect reconstruction of full 3D molecular orbitals without the need for\nsimulations using density functional theory or the like. A major limitation for\nthe direct approach has been the need for densely-sampled, well-calibrated 3D\nphotoemission patterns. Here, we present an iterative projection algorithm that\ncompletely eliminates this challenge: for the benchmark case of the pentacene\nfrontier orbitals, we demonstrate the reconstruction of the full orbital based\non a dataset containing only four simulated photoemission momentum\nmeasurements. We discuss the algorithm performance, sampling requirements with\nrespect to the photon energy, optimal measurement strategies, and the accuracy\nof orbital images that can be achieved.",
        "positive": "The optical absorption spectra of V centers in deformed MgO under\n  pressure: The electronic structure and optical absorption spectrum of V^{0} and V^{-}\ncenter in MgO are investigated using first-principles calculations based on\ndensity functional theory. It is demonstrated that the configuration with\ndistortion is energetically favorable in PBE0 functional. The six O atoms\naround Mg vacancy are non-equivalent due to the distortion. The defect states\nlocalized in the band gap are obtained by applying hybrid functional\ncalculations, which is very important for optical properties. At ambient\ncondition, the absorption peak at ~2.5 and ~2.6 eV is assigned to V^{0} and\nV^{-} center, respectively. With increasing pressure, the absorption peak shows\nblue shift. The trend is consistent with the experimental observation."
    },
    {
        "anchor": "Structure and formation energy of carbon nanotube caps: We present a detailed study of the geometry, structure and energetics of\ncarbon nanotube caps. We show that the structure of a cap uniquely determines\nthe chirality of the nanotube that can be attached to it. The structure of the\ncap is specified in a geometrical way by defining the position of six pentagons\non a hexagonal lattice. Moving one (or more) pentagons systematically creates\ncaps for other nanotube chiralities. For the example of the (10,0) tube we\nstudy the formation energy of different nanotube caps using ab-initio\ncalculations. The caps with isolated pentagons have an average formation energy\n0.29+/-0.01eV/atom. A pair of adjacent pentagons requires a much larger\nformation energy of 1.5eV. We show that the formation energy of adjacent\npentagon pairs explains the diameter distribution in small-diameter nanotube\nsamples grown by chemical vapor deposition.",
        "positive": "Stability of precessing domain walls in ferromagnetic nanowires: We show that recently reported precessing solution of Landau-Lifshitz-Gilbert\nequations in ferromagnetic nanowires is stable under small perturbations of\ninitial data, applied field and anisotropy constant. Linear stability is\nestablished analytically, while nonlinear stability is verified numerically."
    },
    {
        "anchor": "Photocarrier thermalization bottleneck in graphene: We present an ab-initio study of photocarrier dynamics in graphene due to\nelectron-phonon (EP) interactions. Using the Boltzmann relaxation-time\napproximation with parameters determined from density functional theory (DFT)\nand a complementary, explicitly solvable model we show that the photocarrier\nthermalization time changes by orders of magnitude, when the excitation energy\nis reduced from 1 eV to the 100 meV range. In detail, the ultrafast\nthermalization at low temperatures takes place on a femtosecond timescale via\noptical phonon emission, but slows down to picoseconds once excitation energies\nbecome comparable with these optical phonon energy quanta. In the latter\nregime, thermalization times exhibit a pronounced dependence on temperature.\nOur DFT model includes all the inter- and intraband transitions due to EP\nscattering. Thanks to the high melting point of graphene we extend our studies\nup to 2000~K and show that such high temperatures reduce the photocarrier\nthermalization time through phonon absorption.",
        "positive": "Observation of strong-coupling effects in a diluted magnetic\n  semiconductor (Ga,Fe)N: A direct observation of the giant Zeeman splitting of the free excitons in\n(Ga,Fe)N is reported. The magnetooptical and magnetization data imply the\nferromagnetic sign and a reduced magnitude of the effective p-d exchange energy\ngoverning the interaction between Fe^{3+} ions and holes in GaN, N_0 beta^(app)\n= +0.5 +/- 0.2 eV. This finding corroborates the recent suggestion that the\nstrong p-d hybridization specific to nitrides and oxides leads to significant\nrenormalization of the valence band exchange splitting."
    },
    {
        "anchor": "Magnetic anisotropy in Cr$_2$GeC investigated by X-ray magnetic circular\n  dichroism and \\textit{ab initio} calculations: The magnetism in the inherently nanolaminated ternary MAX-phase Cr$_{2}$GeC\nis investigated by element-selective, polarization and temperature-dependent,\nsoft X-ray absorption spectroscopy and X-ray magnetic circular dichroism. The\nmeasurements indicate an antiferro-magnetic Cr-Cr coupling along the $c$-axis\nof the hexagonal structure modulated by a ferromagnetic ordering in the\nnanolaminated $ab$-basal planes. The weak chromium magnetic moments are an\norder of magnitude stronger in the nanolaminated planes than along the vertical\naxis. Theoretically, a small but notable, non-spin-collinear component explains\nthe existence of a non-perfect spin compensation along the $c$-axis. As shown\nin this work, this spin distortion generates an overall residual spin moment\ninside the unit cell resembling that of a ferri-magnet. Due to the different\ncompeting magnetic interactions, electron correlations and temperature effects\nboth need to be considered to achieve a correct theoretical description of the\nCr$_{2}$GeC magnetic properties.",
        "positive": "Determination of nonthermal bonding origin of a novel photoexcited\n  lattice instability in SnSe: Interatomic forces that bind materials are largely determined by an often\ncomplex interplay between the electronic band-structure and the atomic\narrangements to form its equilibrium structure and dynamics. As these forces\nalso determine the phonon dispersion, lattice dynamics measurements are often\ncrucial tools for understanding how materials transform between different\nstructures. This is the case for the mono-chalcogenides which feature a number\nof lattice instabilities associated with their network of resonant bonds and a\nlarge tunability in their functional properties. SnSe hosts a novel lattice\ninstability upon above-bandgap photoexcitation that is distinct from the\ndistortions associated with its high temperature phase transition,\ndemonstrating that photoexcitation can alter the interatomic forces\nsignificantly different than thermal excitation. Here we report decisive\ntime-resolved X-ray scattering-based measurements of the nonequlibrium lattice\ndynamics in SnSe. By fitting interatomic force models to the excited-state\ndispersion, we determine this instability as being primarily due to changes in\nthe fourth-nearest neighbor bonds that connect bilayers, with relatively little\nchange to the intralayer resonant bonds. In addition to providing critical\ninsight into the nonthermal bonding origin of the instability in SnSe, such\nmeasurements will be crucial for understanding and controlling materials\nproperties under non-equilibrium conditions."
    },
    {
        "anchor": "Low-Temperature Optical Characterization of Single CdS Nanowires: We use spatially resolved micro-PL imaging at low temperature to study\noptical properties of two sets of CdS nanowires grown using 20 nm and 50 nm\ncatalysts. We find that low temperature PL of single nanowires is an ideal\ntechnique to gauge the quality of a given growth run, and moreover enables the\ncollection of detailed spatial information on single wire electronic states.",
        "positive": "Machine learning based in situ quality estimation by molten pool\n  condition-quality relations modeling using experimental data: The advancement of machine learning promises the ability to accelerate the\nadoption of new processes and property designs for metal additive\nmanufacturing. The molten pool geometry and molten pool temperature are the\nsignificant indicators for the final part's geometric shape and microstructural\nproperties for the Wire-feed laser direct energy deposition process. Thus, the\nmolten pool condition-property relations are of preliminary importance for in\nsitu quality assurance. To enable in situ quality monitoring of bead geometry\nand characterization properties, we need to continuously monitor the sensor's\ndata for molten pool dimensions and temperature for the Wire-feed laser\nadditive manufacturing (WLAM) system. We first develop a machine learning\nconvolutional neural network (CNN) model for establishing the correlations from\nthe measurable molten pool image and temperature data directly to the geometric\nshape and microstructural properties. The multi-modality network receives both\nthe camera image and temperature measurement as inputs, yielding the\ncorresponding characterization properties of the final build part (e.g., fusion\nzone depth, alpha lath thickness). The performance of the CNN model is compared\nwith the regression model as a baseline. The developed models enable molten\npool condition-quality relations mapping for building quantitative and\ncollaborative in situ quality estimation and assurance framework."
    },
    {
        "anchor": "Hexagonal-to-Cubic Phase Transformation in GaN Nanowires by\n  Ga+-Implantation: Hexagonal to cubic phase transformation is studied in focused ion beam\nassisted Ga+-implanted GaN nanowires. Optical photoluminescence and\ncathodoluminescence studies along with high-resolution transmission electron\nmicroscopic structural studies are performed to confirm the phase\ntransformation. In one possibility, sufficient accumulation of Ga from the\nimplanted source might have reduced the surface energy and simultaneously\nstabilized the cubic phase. Other potential reason may be that the fluctuations\nin the short-range order induced by enhanced dynamic annealing (defect\nannihilation) with the irradiation process stabilize the cubic phase and cause\nthe phase transformation.",
        "positive": "Laser scribing on HOPG for graphene stamp printing on silicon wafer: Highly oriented pyrolytic graphite (HOPG) was scribed by pulsed laser beam to\nproduce square patterns. Patterning of HOPG surface facilitates the detachment\nof graphene layers during contact printing. Direct HOPG-to-substrate and\nglue-assisted stamp printing of a few-layers graphene was compared. Printed\ngraphene sheets were visualized by optical and scanning electron microscopy.\nThe number of graphene layers was measured by atomic force microscopy.\nGlue-assisted stamp printing allows printing relatively large graphene sheets\n(40x40 microns) onto a silicon wafer, which can be important for\nmicroelectronics fabrication. The presented method is easier to implement and\nis more flexible than the majority of existing ways of placing graphene sheets\nonto a substrate."
    },
    {
        "anchor": "First-principles study of exchange coupling constants in\n  Nd$_x$Fe$_{1-x}$ amorphous alloy: We investigate the exchange coupling constant $J_{ij}$ in Nd$_x$Fe$_{1-x}$\namorphous alloys with different compositions within the framework of\nfirst-principles calculation. We observed a strong atomic-dependence of\n$J_{ij}$ and its fluctuations. We show that the composition strongly affects\nthe distance dependence of $J_{ij}$. Composition dependence of calculated Curie\ntemperatures is modest for $x<0.5$. To examine the effect of the local\nenvironment on the exchange couplings, we demonstrate combined analyses of the\ncoordination structure and exchange coupling constants using the Gabriel graph.\nOur study reveals that the Curie temperatures are mostly dominated by the\naveraged $J_{ij}$ and coordination numbers determined by the pairs of\nneighboring atoms. We also observed that the exchange couplings between Fe--Fe\nand Fe--Nd become stronger with increasing the number of surrounding Nd atoms.",
        "positive": "Atomistic studies of thin film growth: We present here a summary of some recent techniques used for atomistic\nstudies of thin film growth and morphological evolution. Specific attention is\ngiven to a new kinetic Monte Carlo technique in which the usage of unique\nlabeling schemes of the environment of the diffusing entity allows the\ndevelopment of a closed data base of 49 single atom diffusion processes for\nperiphery motion. The activation energy barriers and diffusion paths are\ncalculated using reliable manybody interatomic potentials. The application of\nthe technique to the diffusion of 2-dimensional Cu clusters on Cu(111) shows\ninteresting trends in the diffusion rate and in the frequencies of the\nmicroscopic mechanisms which are responsible for the motion of the clusters, as\na function of cluster size and temperature. The results are compared with those\nobtained from yet another novel kinetic Monte Carlo technique in which an open\ndata base of the energetics and diffusion paths of microscopic processes is\ncontinuously updated as needed. Comparisons are made with experimental data\nwhere available."
    },
    {
        "anchor": "Spin-momentum locked polariton transport in the chiral strong coupling\n  regime: We demonstrate room temperature chiral strong coupling of valley excitons in\na transition metal dichalcogenide monolayer with spin-momentum locked surface\nplasmons. In this regime, we measure spin-selective excitation of directional\nflows of polaritons. Operating under strong light-matter coupling, our platform\nyields robust intervalley contrasts and coherences, enabling us to generate\ncoherent superpositions of chiral polaritons propagating in opposite\ndirections. Our results reveal the rich and easy to implement possibilities\noffered by our system in the context of chiral optical networks.",
        "positive": "Amorphous Bi$_2$Se$_3$ structural, electronic, and topological nature by\n  first-principles: Crystalline $\\rm Bi_2Se_3$ is one of the most explored three-dimensional\ntopological insulator, with a $0.3\\;\\rm eV$ energy gap making it promising for\napplications. Its amorphous counterpart could bring to light new possibilities\nfor large scale synthesis and applications. Using ab initio molecular dynamics\nsimulations, we have studied realistic amorphous $\\rm Bi_2Se_3$ phases\ngenerated by different processes of melting, quenching, and annealing.\nExtensive structural and electronic characterizations show that the melting\nprocess induces an energy gap decrease ruled by growth of the defective local\nenvironments. This behavior dictates a weak stability of the topological phase\nto disorder, characterized by the spin Bott index. Interestingly, we identify\nthe occurrence of topologically trivial surface states in amorphous $\\rm\nBi_2Se_3$ that show a strong resemblance with standard helical topological\nstates. Our results and methods advance the search of topological phases in\nthree-dimensional amorphous solids."
    },
    {
        "anchor": "Nonconventional magnetic phenomena in neodymium thin film: Neodymium is a remarkable active component in numerous magnetic alloys that\nare used in various applications. However, the application of bare neodymium\nthin film is limited due to the lack of information about its electrical and\nmagnetic properties. We report synergistic study of Nd thin film using\nexperimental and theoretical techniques of polarized neutron reflectometry,\nmagnetoresistance measurement and density functional theory. Unlike bulk Nd,\nthin film specimen is a very poor electrical conductor. Also, as grown thin\nfilm on silicon substrate does not exhibit any magnetism in zero field.\nHowever, moderate inplane field application of $H$ = 1.2 T tends to induce weak\nmagnetism in the system at low temperature of $T$ $<$ 18 K, which coincides\nwith an unusual cross-over behavior in magnetoresistance. The study provides\nimportant insight in the physical characteristics of Nd thin film that are\natypical for a magnetic system.",
        "positive": "Short-Range Order Structure Motifs Learned from an Atomistic Model of a\n  Zr$_{50}$Cu$_{45}$Al$_{5}$ Metallic Glass: The structural motifs of a Zr$_{50}$Cu$_{45}$Al$_{5}$ metallic glass were\nlearned from atomistic models using a new structure analysis method called\nmotif extraction that employs point-pattern matching and machine learning\nclustering techniques. The motifs are the nearest-neighbor building blocks of\nthe glass and reveal a well-defined hierarchy of structures as a function of\ncoordination number. Some of the motifs are icosahedral or quasi-icosahedral in\nstructure, while others take on the structure of the most close-packed\ngeometries for each coordination number. These results set the stage for\ndeveloping clearer structure-property connections in metallic glasses. Motif\nextraction can be applied to any disordered material to identify its structural\nmotifs without the need for human input."
    },
    {
        "anchor": "Magnetic Structure and dielectric properties of antiferromagnetic FeCrO3: We report the enhancement of N\\'eel temperature of Cr2O3 by replacing 50% of\nCr by Fe prepared by sol-gel method. The structural analysis by neutron\ndiffraction has revealed that FeCrO3 belongs to a corundum structure (R-3c\nspace group) with an antiferromagnetic spin structure having collinear spins\nalong a-axis with propagation vector k=0; the high-temperature magnetisation\nstudy indicated a N\\'eel temperature of 560 K. The enhancement in N\\'eel\ntemperature has been attributed to the strong orbital hybridization that leads\nto change in nearest neighbor bond angle and bond distances. Impedance\nspectroscopy has revealed conduction mechanism at low temperature is due to the\npolaron hopping while extrinsic contributions from the Maxwell-Wagner dominant\nat high temperatures",
        "positive": "Hybrid density functional study of band gap engineering of SrTiO3\n  photocatalyst via doping for water splitting: Perovskite SrTiO3 (STO) is an attractive photocatalyst for solar water\nsplitting, but suffers from a limited photoresponse in the ultraviolet spectral\nrange due to its wide band gap. By means of hybrid density functional theory\ncalculations, we systematically study engineering its band gap via doping 4d\nand 5d transition metals M (M=Zr, Nb, Mo, Tc, Ru, Rh, Pd, Hf, Ta, W, Re, Os, Ir\nand Pt) and chalcogen elements Y (Y=S and Se). We find that transition metal\ndopant M either has no effect on STO band gap or introduces detrimental mid-gap\nstates, except for Pd and Pt that are able to reduce the STO band gap. In\ncontrast, doping S and Se significantly reduces STO's direct band gap, thus\nleading to appreciable optical absorption transitions in the visible spectral\nrange. Our findings provide that Pd, S and Se doped STO are potential promising\nphotocatalysts for water splitting under visible light irradiation, thereby\nproviding insightful theoretical guides for experiments to improve the\nphotocatalytic activity of STO."
    },
    {
        "anchor": "Quasi-two-dimensional heterostructures (K$M_{1-x}$Te)(LaTe$_{3}$) ($M$ =\n  Mn, Zn) with charge density waves: Layered heterostructure materials with two different functional building\nblocks can teach us about emergent physical properties and phenomena arising\nfrom interactions between the layers. We report the intergrowth compounds\nKLa$M$$_{1-x}$Te$_{4}$ ($M$ = Mn, Zn; $x\\approx$ 0.35) featuring two chemically\ndistinct alternating layers [LaTe$_3$] and [K$M$$_{1-x}$Te]. Their crystal\nstructures are incommensurate, determined by single X-ray diffraction for the\nMn compound and transmission electron microscope (TEM) study for the Zn\ncompound. KLaMn$_{1-x}$Te$_{4}$ crystallizes in the orthorhombic superspace\ngroup $Pmnm$(01/2${\\gamma}$)$s$00 with lattice parameters $a$ = 4.4815(3)\n{\\AA}, $b$ = 21.6649(16) {\\AA} and $c$ = 4.5220(3) {\\AA}. It exhibits charge\ndensity wave (CDW) order at room temperature with a modulation wave vector\n$\\mathbf{q}$ = 1/2$\\mathbf{b}$* + 0.3478$\\mathbf{c}$* originating from\nelectronic instability of Te-square nets in [LaTe$_{3}$] layers. The Mn analog\nexhibits a cluster spin glass behavior with spin freezing temperature\n$T_{\\mathrm{f}}$ $\\approx$ 5 K attributed to disordered Mn vacancies and\ncompeting magnetic interactions in the [Mn$_{1-x}$Te] layers. The Zn analog\nalso has charge density wave order at room temperature with a similar\n$\\mathbf{q}$-vector having the $\\mathbf{c}$* component ~ 0.346 confirmed by\nselected-area electron diffraction (SAED). Electron transfer from\n[K$M_{1-x}$Te] to [LaTe$_{3}$] layers exists in KLa$M_{1-x}$Te$_{4}$, leading\nto an enhanced electronic specific heat coefficient. The resistivities of\nKLa$M_{1-x}$Te$_{4}$ ($M$ = Mn, Zn) exhibit metallic behavior at high\ntemperatures and an upturn at low temperatures, suggesting partial localization\nof carriers in the [LaTe$_{3}$] layers with some degree of disorder associated\nwith the $M$ atom vacancies in the [$M_{1-x}$Te] layers.",
        "positive": "Spin waves in paramagnetic BCC iron: spin dynamics simulations: Large scale computer simulations are used to elucidate a longstanding\ncontroversy regarding the existence, or otherwise, of spin waves in\nparamagnetic BCC iron. Spin dynamics simulations of the dynamic structure\nfactor of a Heisenberg model of Fe with first principles interactions reveal\nthat well defined peaks persist far above Curie temperature T_c. At large wave\nvectors these peaks can be ascribed to propagating spin waves, at small wave\nvectors the peaks correspond to over-damped spin waves. Paradoxically, spin\nwave excitations exist despite only limited magnetic short-range order at and\nabove T_c."
    },
    {
        "anchor": "Predicting Novel Properties in Two-Dimensional Janus Transition Metal\n  Hydrosulfides with 2H and 1T Phases: Electrodes, Charge Density Waves, and\n  Superconductivity: Inspired by recent experimental synthesis of the two-dimensional Janus\nmaterial MoSH, we performed extensive first-principles calculations to\ninvestigate the characteristics of all possible Janus two-dimensional\ntransition metal hydrosulfides (JTMSHs) in both the 2H and 1T phases. Our\ninvestigations revealed that the JTMSHs can form a unique family of\ntwo-dimensional materials with novel physical and chemical properties. We found\nthat JTMSHs can exist in different crystal states, exhibiting metallic,\nsemiconducting, and magnetic behaviors. One particularly intriguing finding is\nthe identification of two-dimensional electrodes with distinct bonding\ncharacteristics in the 2H-JTMSHs (TM=V, Nb, Ta, Mo, W and Tc). Additionally, we\nobserved evidence of charge density wave (CDW) materials in 1T-JTMSH (TM=Tc,\nRe, and W) and 2H-JTMSH (TM = Tc). Importantly, by applying a compressive\nstrain to these materials, the CDW can be completely suppressed and\nsuperconductivities is hence induced. Specially, we shown that when subjected\nto a compressive strain within 10%, the superconducting transition temperature\n(Tc) of 1T-WSH, 1T-TcSH and 2H-TcSH can achieve maximum values of 13.8, 16.2\nand 24.2 K respectively. Additionally, our investigation also unveiled two\nintrinsic phonon-mediated superconductors 2H-WSH and 1T-RuSH with Tc of 17.0 K\nand 8K, respectively. Overall, our results demonstrate that the family of\ntwo-dimensional JTMSHs is full of surprises and holds great potential for\nfuture exploration.",
        "positive": "Nonlinear geometric effects in mechanical bistable morphing structures: Bistable structures associated with non-linear deformation behavior,\nexemplified by the Venus flytrap and slap bracelet, can switch between\ndifferent functional shapes upon actuation. Despite numerous efforts in\nmodeling such large deformation behavior of shells, the roles of mechanical and\nnonlinear geometric effects on bistability remain elusive. We demonstrate,\nthrough both theoretical analysis and table-top experiments, that two\ndimensionless parameters control bistability. Our work classifies the\nconditions for bistability, and extends the large deformation theory of plates\nand shells."
    },
    {
        "anchor": "Pulsed Laser Deposition of High-Quality Thin Films of the Insulating\n  Ferromagnet EuS: High-quality thin films of the ferromagnetic-insulator europium(II) sulfide\n(EuS) were fabricated by pulsed laser deposition on Al2O3 (0001) and Si (100)\nsubstrates. A single orientation was obtained with the [100] planes parallel to\nthe substrates, with atomic-scale smoothness indicates a near-ideal surface\ntopography. The films exhibit uniform ferromagnetism below 15.9 K, with a\nsubstantial component of the magnetization perpendicular to the plane of the\nfilms. Optimization of the growth condition also yielded truly insulating films\nwith immeasurably large resistance. This combination of magnetic and electric\nproperties open the gate for novel devices that require a true ferromagnetic\ninsulator.",
        "positive": "In situ atomic force microscopy depth-corrected 3-dimensional focused\n  ion beam based time-of-flight secondary ion mass spectroscopy: spatial\n  resolution, surface roughness, oxidation: Atomic force microscopy (AFM) is a well-known tool for studying surface\nroughness and to collect depth information about features on the top atomic\nlayer of samples. By combining secondary ion mass spectroscopy (SIMS) with\nfocused ion beam (FIB) milling in a scanning electron microscope (SEM),\nchemical information of sputtered structures can be visualized and located with\nhigh lateral and depth resolution. In this paper, a high vacuum (HV) compatible\nAFM has been installed in a TESCAN FIB-SEM instrument that was equipped with a\ntime-of-flight secondary ion mass spectroscopy (ToF-SIMS) detector. To\ninvestigate the crater's depth caused by the ToF-SIMS sputtering, subsequent\nAFM measurements were performed on a multilayer vertical cavity surface\nemitting laser (VCSEL) sample. Surface roughness and milling depth were used to\naid accurate 3D reconstruction of the sputtered volume's chemical composition.\nAchievable resolution, surface roughness during sputtering and surface\noxidation issues are analysed. Thus, the integration of complementary detectors\nopens up the ability to determine the sample properties as well as to\nunderstand the influence of the analysis method on the sample surface during\nthe analysis."
    },
    {
        "anchor": "Effect of aging on the reinforcement efficiency of carbon nanotubes in\n  epoxy matrix: The reinforcement efficiency of carbon nanotubes (CNTs) in epoxy matrix was\ninvestigated in the elastic regime. Cyclic uniaxial tensile tests were\nperformed at constant strain amplitude and increasing maximum strain.\nPost-curing of the epoxy and its composite at a temperature close to the glass\ntransition temperature allowed us to explore the effect of aging on the\nreinforcement efficiency of CNT. It is found that the reinforcement efficiency\nis compatible with a mean field mixture rule of stress reinforcement by random\ninclusions. It also diminishes when the maximum strain increased and this\neffect is amplified by aging. The decrease of elastic modulus with increasing\ncyclic maximum strain is quite similar to the one observed for filled\nelastomers with increasing strain amplitude, a phenomenon often referred as the\nPayne effect.",
        "positive": "Deep analytics of atomically-resolved images: manifest and latent\n  features: Recent advances in scanning transmission electron and scanning tunneling\nmicroscopies allow researchers to measure materials structural and electronic\nproperties, such as atomic displacements and charge density modulations, at an\nAngstrom scale in real space. At the same time, the ability to quickly acquire\nlarge, high-resolution datasets has created a challenge for rapid physics-based\nanalysis of images that typically contain several hundreds to several thousand\natomic units. Here we demonstrate a universal deep-learning based framework for\nlocating and characterizing atomic species in the lattice, which can be applied\nto different types of atomically resolved measurements on different materials.\nSpecifically, by inspecting and categorizing features in the output layer of a\nconvolutional neural network, we are able to detect structural and electronic\n'anomalies' associated with the presence of point defects in a tungsten\ndisulfide monolayer, non-uniformity of the charge density distribution around\nspecific lattice sites on the surface of strongly correlated oxides, and\ntransition between different structural states of buckybowl molecules. We\nfurther extended our method towards tracking, from one image frame to another,\nminute distortions in the geometric shape of individual Si dumbbells in a\n3-dimensional Si sample, which are associated with a motion of lattice defects\nand impurities. Due the applicability of our framework to both scanning\ntunneling microscopy and scanning transmission electron microscopy\nmeasurements, it can provide a fast and straightforward way towards creating a\nunified database of defect-property relationships from experimental data for\neach material."
    },
    {
        "anchor": "Topological Lifshitz transition and one-dimensional Weyl mode in HfTe5: Landau band crossings typically stem from the intra-band evolution of\nelectronic states in magnetic fields and enhance the interaction effect in\ntheir vicinity. Here in the extreme quantum limit of topological insulator\nHfTe5, we report the observation of a topological Lifshitz transition from\ninter-band Landau level crossings using magneto-infrared spectroscopy. By\ntracking the Landau level transitions, we demonstrate that band inversion\ndrives the zeroth Landau bands to cross with each other after 4.5 T and forms\none-dimensional Weyl mode with fundamental gap persistently closed. The unusual\nreduction of the zeroth Landau level transition activity suggests a topological\nLifshitz transition at 21 T which shifts the Weyl mode close to Fermi level. As\na result, a broad and asymmetric absorption feature emerges due to the Pauli\nblocking effect in one dimension, along with a distinctive negative\nmagneto-resistivity. Our results provide a strategy for realizing\none-dimensional Weyl quasiparticles in bulk crystals.",
        "positive": "Tuning the lattice thermal conductivity in van-der-Waals structures\n  through rotational (dis)ordering: It has recently been demonstrated that MoS2 with irregular interlayer\nrotations can achieve an extreme anisotropy in the lattice thermal conductivity\n(LTC), which is for example of interest for applications in waste heat\nmanagement in integrated circuits. Here, we show by atomic scale simulations\nbased on machine-learned potentials that this principle extends to other\ntwo-dimensional materials including C and BN. In all three materials\nintroducing rotational disorder drives the through-plane LTC to the glass\nlimit, while the in-plane LTC remains almost unchanged compared to the ideal\nbulk materials. We demonstrate that the ultralow through-plane LTC is connected\nto the collapse of their transverse acoustic modes in the through-plane\ndirection. Furthermore, we find that the twist angle in periodic moir\\'e\nstructures representing rotational order provides an efficient means for tuning\nthe through-plane LTC that operates for all chemistries considered here. The\nminimal through-plane LTC is obtained for angles between 1 and 4 degree\ndepending on the material, with the biggest effect in MoS2. The angular\ndependence is correlated with the degree of stacking disorder in the materials,\nwhich in turn is connected to the slip surface. This provides a simple\ndescriptor for predicting the optimal conditions at which the LTC is expected\nto become minimal."
    },
    {
        "anchor": "An Assessment of Thermally Driven Local Structural Phase Changes in\n  1$T$$'$- MoTe$_2$: The role of layer disorder is important in establishing the topological\nphases of MoTe${_2}$. A rich tapestry of atomic ordering influences the\nstructural phase transitions (SPTs), but there is little understanding of the\nmechanistic details of the phase transition. An atomistic level study was\nconducted to investigate the local structure of the 1$T$$'$ and $T_d$ phases of\nMoTe${_2}$ by using the Pair Distribution Function (PDF) technique. While the\naverage structure exhibits an SPT and co-existence of phases as a function of\ntemperature, the local structure shows the suppression of SPT at short-range\nordering, and the sample remains in the monoclinic (1$T$$'$) phase at all\nmeasured temperatures. A sharp PDF peak observed at short distances indicated a\nstrong atom-atom correlation between the Mo and Te atoms within the\nMo-octahedra. In addition, a large box modeling of the PDF data indicated a\npreferential motion of Te atoms towards $c$-axis at all temperatures. The\nstructural defects, such as stacking faults, likely result in the co-existence\nof phases in the average structure and suppress the local SPT of MoTe$_2$.\nThese results are stepping stones in understanding the long-debated origins of\nstructural, vibrational, and electronic properties of MoTe$_2$ and similar\ntransition metal dichalcogenides.",
        "positive": "Possible martensitic transformation in Pd2MnTi and Pt2MnTi:\n  First-principles investigation: The martensitic transformation in new-type all-d-metal Heusler alloys Pd2MnTi\nand Pt2MnTi have been investigated based on first-principles investigations.\nThe calculated results indicate that the martenstic transformation have great\npossibility to occur in both Pd2MnTi and Pt2MnTi. The energy differences\nbetween the cubic and tetragonal phases are 215.12 meV and 329.45 meV for\nPd2MnTi and Pt2MnTi, respectively. The analysis of the electronic structure of\ncubic and tetragonal phases also support this conclusion. The magnetic\nproperties are also investigated for the two compounds."
    },
    {
        "anchor": "Pure shear axes and elastic strain energy: It is well known that a state of pure shear has distinct sets of basis\nvectors or coordinate systems: the principal axes, in which the stress is\ndiagonal, and pure shear bases, in which diag(stress)=0. The latter is commonly\ntaken as the definition of pure shear, although a state of pure shear is more\ngenerally defined by tr(stress)=0. New results are presented that characterize\nall possible pure shear bases. A pair of vector functions are derived which\ngenerate a set of pure shear basis vectors from any one member of the triad.\nThe vector functions follow from compatibility condition for the pure shear\nbasis vectors, and are independent of the principal stress values. The\ncomplementary types of vector basis have implications for the strain energy of\nlinearly elastic solids with cubic material symmetry: for a given state of\nstress or strain, the strain energy achieves its extreme values when the\nmaterial cube axes are aligned with principal axes of stress or with a pure\nshear basis. This implies that the optimal orientation for a given state of\nstress is with one or the other vector basis, depending as the stress is to be\nminimized or maximized, which involves the sign of one material parameter.",
        "positive": "Canted antiferromagnetism in high purity $\\mathrm{NaFeF_3}$ prepared by\n  a novel wet-chemical synthesis method: We report a novel synthesis method for, and structural and magnetic\ncharacterization of the fluoroperovskite $\\mathrm{NaFeF_3}$. We have developed\na wet-chemical method that allows preparation of large volumes of air-sensitive\nfluoroperovskites with high purity. $\\mathrm{NaFeF_3}$ has a N\\'eel temperature\n($T_N$) of 90 K and a Weiss constant ($\\theta$) of -124 K, corresponding to\ndominant antiferromagnetic interactions. Below $T_N$, a slight difference is\nobserved between zero-field and field cooled samples, indicating spin-canting\nand weak ferromagnetism. AC magnetometry confirms that weak ferromagnetism is\ninherent to $\\mathrm{NaFeF_3}$ and not due to impurities. From powder neutron\ndiffraction data, we describe the magnetic structure precisely as a weakly\ncanted G-type (magnetic space group $Pn'ma'$). A ferromagnetic component is\nallowed in $Pn'ma'$, however, this component may be absent in zero magnetic\nfields and is too small to be confirmed on the basis of powder neutron\ndiffraction data."
    },
    {
        "anchor": "Spintronics of metal ferromagnetic structures: New approaches in the\n  theory and experiments: Two channels of the sd exchange interaction are considered in magnetic\njunctions. The first channel describes the interaction of transversal spins\nwith the lattice magnetization. The second one describes the interaction of\nlongitudinal spins with magnetization. We show the longitudinal channel leads\nto a number of significant effects: 1) drastic lowering of the current\ninstability threshold down to three (or even more) orders of magnitude; 2)\ncreation of large enough distortion of equilibrium due to current driven spin\ninjection leading to inversion of energy spin subband populations and\nlaser-like instability in THz frequency range at room temperature. External\nmagnetic field may tend to lower additionally the instability threshold due to\nthe proximity effect of purely magnetic reorientation phase transition. This\neffect demonstrates the new properties: the giant magnetoresistance (GMR)\nbecomes strongly current dependent and the exchange switching becomes of very\nlow threshold. We derived some matching condition that should be satisfied to\nachieve high spin injection level. Some characteristic quantities were appeared\nin the condition. We investigated also the junctions having variable lateral\ndimensions of the layers, for example, a ferromagnetic rod contacting with a\nvery thin ferromagnetic film. Large enhancement of the current density may\nappear near the contact region leading to the spin injection luminescence.",
        "positive": "Effect of doping on SGS and weak half-metallic properties of inverse\n  Heusler Alloys: Heusler alloys with Mn and Co have been found to exhibit interesting\nelectronic and magnetic properties. Mn$_2$CoAl is well known SGS compound while\nMn$_2$CoGa has weak half metallic character. By using plane wave\npseudo-potential method, we studied the effect of Fe and Cr doping on\nhalf-metalicity and magnetism of these compounds. The doping destroys the SGS\nnature of Mn$_2$CoAl while the small-scale doping enhance the half-metallicity\nof Mn$_2$CoGa making it perfect half-metal. In case of Mn$_2$CoAl, the doping\ndecrease the band gap while increase in band width is noticed for Mn$_2$CoGa.\nThe half-metallicity is destroyed in both cases when the doping level is beyond\ncertain degree. Moreover, we have also computed magnetic behavior of Mn$_2$CoZ\nalloys and we found that total magnetic moments of dopped samples have higher\nvalues than that of pristine compounds."
    },
    {
        "anchor": "Griffiths like Robust Ferromagnetism in Co3-xMnxTeO6; (x = 0.5, 1, 2): We report near room temperature ferromagnetic as well as low temperature\nantiferromagnetic correlations in Mn doped Cobalt Tellurate (CMTO) solid\nsolutions using thorough magnetization studies. For all the composition the\nsolid solutions show not only short range robust FM order at 185 K but also\nshow long range enhanced AFM order less than or equal to 45 K. Scaling of\ninverse magnetic susceptibility data provide clear indication of Griffiths like\nFM phase extended over large thermal region and its robustness against magnetic\nfield. Variations in both the phases as a function of Mn concentration also\nsupport our observation of anomalous behavior in the average bond distances and\ncharge states (JAP 116: 074904 (2014)). Further an attempt towards the\nstructural insight into the observed complex magnetic behavior by using network\nlike structural analysis has been drawn. These observations make this an\ninteresting magnetic system from fundamental and application perspective.",
        "positive": "Metal-Boron Nanotubes: Nanotubular materials inspired by crystalline diborides such as AlB_2 are\nproposed. The atomic structure, in particular the basic chemical question of\nwhere to put Al atoms in order to stabilize nanotubular Al-B systems, is\ninvestigated using density-functional calculations for prototype systems. The\noptimized tubular prototypes are found to be competitive in energy with their\nbulk crystalline counterparts. All of the tubular Al-B systems investigated are\ncalculated to be metallic."
    },
    {
        "anchor": "Mechanics and Tunable Bandgap by Straining in Single-Layer Hexagonal\n  Boron-Nitride: Current interest in two-dimensional materials extends from graphene to others\nsystems like single-layer hexagonal boron-nitride (h-BN), for the possibility\nof making heterogeneous structures to achieve exceptional properties that\ncannot be realized in graphene.The electrically insulating h-BN and semi-metal\ngraphene may open good opportunities to realize a semiconductor by manipulating\nthe morphology and composition of such heterogeneous structures.Here we report\nthe mechanical properties of h-BN and its band structures tuned by mechanical\nstraining by using the density functional theory calculations.The elastic\nproperties, both the Young's modulus and bending rigidity for h-BN, are\nisotropic.We reveal that there is a bi-linear dependence of band gap on the\napplied tensile strains in h-BN. Mechanical strain can tune single-layer h-BN\nfrom an insulator to a semiconductor, with a band gap in the 4.7eV to 1.5eV\nrange.",
        "positive": "Identification of Si-vacancy related room temperature qubits in 4H\n  silicon carbide: Identification of microscopic configuration of point defects acting as\nquantum bits is a key step in the advance of quantum information processing and\nsensing. Among the numerous candidates, silicon vacancy related centers in\nsilicon carbide (SiC) have shown remarkable properties owing to their\nparticular spin-3/2 ground and excited states. Although, these centers were\nobserved decades ago, still two competing models, the isolated negatively\ncharged silicon vacancy and the complex of negatively charged silicon vacancy\nand neutral carbon vacancy [Phys. Rev. Lett.\\ \\textbf{115}, 247602 (2015)] are\nargued as an origin. By means of high precision first principles calculations\nand high resolution electron spin resonance measurements, we here unambiguously\nidentify the Si-vacancy related qubits in hexagonal SiC as isolated negatively\ncharged silicon vacancies. Moreover, we identify the Si-vacancy qubit\nconfigurations that provide room temperature optical readout."
    },
    {
        "anchor": "Highly Tunable and Strong Bound Exciton in MoSi2N4 via Strain\n  Engineering: Motivated by the recently synthesized layered material MoSi2N4, we\ninvestigated excitonic response of quasiparticle of monolayer MoSi2N4 by using\nG0W0 and Bethe-Salpeter equation (BSE) calculations. With a dually sandwiched\nstructure consisting of a central MoN2 layer analogue of 2H-MoS2 capped with\nsilicon-nitrogen (SiN) honeycomb outer layers, MoSi2N4 possesses frontier\norbitals confined at the central MoN2 layer with similar sub-valley at K-point\nas 2H-MoS2. The valley splitting (~130 meV) due to the spin-orbital coupling\n(SOC) gives rise to a doublet in the spectrum. Excitons in MoSi2N4 shows a\nstrong binding energy up to 0.95 eV with the optical bandgap of 2.44 eV. Both\nelectronic and optical gaps are highly sensitive to tensile strains and become\nredshift albeit a marginal change of exciton binding energy. With the\nprotection of capped SiN layers, quantum confined excitons in MoSi2N4 without\nthe need of additional passivation layer like BN would provide a bright new\nplatform for robust emission with partially screened disturbance from\nenvironment.",
        "positive": "Electronic Transport Imaging in a Multiwire SnO2 ChemFET Device: The electronic transport and the sensing performance of an individual SnO2\ncrossed nanowires device in a three-terminal field effect configuration were\ninvestigated using a combination of macroscopic transport measurements and\nScanning Surface Potential Microscopy (SSPM). The structure of the device was\ndetermined using both Scanning Electron- and Atomic Force Microscopy data. The\nSSPM images of two crossed 1D nanostructures, simulating a prototypical\nnanowire network sensors, exhibit large dc potential drops at the crossed-wire\njunction and at the contacts, identifying them as the primary electroactive\nelements in the circuit. The gas sensitivity of this device was comparable to\nthose of sensors formed by individual homogeneous nanostructures of similar\ndimensions. Under ambient conditions, the DC transport measurements were found\nto be strongly affected by field-induced surface charges on the nanostructure\nand the gate oxide. These charges result in a memory effect in transport\nmeasurements and charge dynamics which are visualized by SSPM. Finally,\nscanning probe microscopy is used to measure the current-voltage\ncharacteristics of individual active circuit elements, paving the way to a\ndetailed understanding of chemical functionality at the level of an individual\nelectroactive element in an individual nanowire."
    },
    {
        "anchor": "Modeling Electrochemical Decomposition of Fluoroethylene Carbonate on\n  Silicon Anode Surfaces in Lithium Ion Batteries: Fluoroethylene carbonate (FEC) shows promise as an electrolyte additive for\nimproving passivating solid-electrolyte interphase (SEI) films on silicon\nanodes used in lithium ion batteries (LIB). We apply density functional theory\n(DFT), ab initio molecular dynamics (AIMD), and quantum chemistry techniques to\nexamine excess-electron-induced FEC molecular decomposition mechanisms that\nlead to FEC-modified SEI. We consider one- and two-electron reactions using\ncluster models and explicit interfaces between liquid electrolyte and model\nLi(x)Si(y) surfaces, respectively. FEC is found to exhibit more varied reaction\npathways than unsubstituted ethylene carbonate. The initial bond-breaking\nevents and products of one- and two-electron reactions are qualitatively\nsimilar, with a fluoride ion detached in both cases. However, most one-electron\nproducts are charge-neutral, not anionic, and may not coalesce to form\neffective Li+-conducting SEI unless they are further reduced or take part in\nother reactions. The implications of these reactions to silicon-anode based LIB\nare discussed.",
        "positive": "Engineering Ferroelectric Hf0.5Zr0.5O2 Thin Films by Epitaxial Stress: The critical impact of epitaxial stress on the stabilization of the\nferroelectric orthorhombic phase of hafnia is proved. Epitaxial bilayers of\nHf0.5Zr0.5O2 and La0.67Sr0.33MnO3 electrodes were grown on a set of single\ncrystalline oxide 001-oriented, cubic or pseudocubic setting, substrates with\nlattice parameter in the 3.71 - 4.21 A range. The lattice strain of the\nLa0.67Sr0.33MnO3 electrode, determined by the lattice mismatch with the\nsubstrate, is critical in the stabilization of the orthorhombic phase of\nHf0.5Zr0.5O2. On La0.67Sr0.33MnO3 electrodes tensile strained most of the\nHf0.5Zr0.5O2 film is orthorhombic, whereas the monoclinic phase is favored when\nLa0.67Sr0.33MnO3 is relaxed or compressively strained. Therefore, the\nHf0.5Zr0.5O2 films on TbScO3 and GdScO3 substrates present substantially\nenhanced ferroelectric polarization in comparison to films on other substrates,\nincluding the commonly used SrTiO3. The capability of having epitaxial doped\nHfO2 films with controlled phase and polarization is of major interest for a\nbetter understanding of the ferroelectric properties and paves the way for\nfabrication of ferroelectric devices based on nanometric HfO2 films."
    },
    {
        "anchor": "Ultrafast and gigantic spin injection in semiconductors: The injection of spin currents in semiconductors is one of the big challenges\nof spintronics. Motivated by the ultrafast demagnetisation and spin injection\ninto metals, we propose an alternative femtosecond route based on the laser\nexcitation of superdiffusive spin currents in a ferromagnet such as Ni. Our\ncalculations show that even though only a fraction of the current crosses the\nNi-Si interface, the laser-induced creation of strong transient electrical\nfields at a ferromagnet-semiconductor interface allows for the injection of\nchargeless spin currents with a record spin polarisations of 80%. Beyond that\nthey are pulsed on the time scale of 100 femtoseconds which opens the door for\nnew experiments and ultrafast spintronics.",
        "positive": "Ligand Directed Self-Assembly of Bulk Organic-Semiconductor/Quantum-Dot\n  Blend Films Enables Near Quantitative Harvesting of Triplet Excitons: Singlet fission (SF), an exciton multiplication process occurring in organic\nsemiconductors, offers a way to break the Shockley-Queisser limit in\nsingle-bandgap photovoltaics (PV). If the triplet excitons generated by SF can\nbe transferred to inorganic quantum dots (QDs), where they radiatively\nrecombine, SF based photon multiplication is achieved, converting a single\nhigh-energy photon into two low-energy photons. Such a SF photon multiplication\nfilm (SF-PMF) could raise the efficiency of the best Si-PV from 26.7% to 32.5%.\nBut a precise nanoscale morphology is required within such a film consisting of\nthe appropriate morphology for the organic phase, allowing for efficient SF,\nwithin which the QD emitters are well dispersed on a tens of nm length scale to\nenable efficient harvesting of the triplets. However, it has been a\nlong-standing problem that the individual components in organic-QD blends have\na tendency to aggregate and phase separate, due to a mismatch of their size,\nshape and surface energies. Here, we demonstrate a QD surface engineering\napproach using an electronically active, highly soluble semiconductor ligand\nthat is matched to the SF material, which allows us to direct the self-assembly\nprocess yielding solution processed films with well-dispersed QDs and minimal\naggregation, as characterised by X-ray and neutron scattering and electron\nmicroscopy. Steady state and time-resolved optical spectroscopy show that the\nfilms support efficient SF (190% yield) in the organic phase and quantitative\ntriplet energy transfer across the organic-QD interface, resulting in 95% of\nthe triplet excitons being harvested by the QDs. Our results establish the\nSF-PMF as a highly promising architecture to harness the SF process to enhance\nPV efficiencies, and also provide a highly versatile approach to overcome\nchallenges in the blending of organic semiconductors with QDs."
    },
    {
        "anchor": "Transmission in a Fano-Anderson chain with a topological defect: The Fano-Anderson chain consists of a linear lattice with a discrete\nside-unit, and exhibits Fano-resonant scattering due to coupling between the\ndiscrete states of the side-unit with the tight-binding continuum. We study\nFano-resonance-assisted transport for the case of a topologically non-trivial\nside unit. We find that the topology of the side unit influences the\ntransmission characteristics which thus can be an effective detection tool of\nthe topological phases of the side unit. Furthermore, we explore the role of\ndual links between the linear tight-binding chain and the side unit. The\nsecondary connection between the main chain and the side unit can modify the\nposition or width of the Fano resonance dip in the transmission probability,\nand thus yield additional control.",
        "positive": "Intrinsic and extrinsic corrugation of monolayer graphene deposited on\n  SiO2: Using scanning tunneling microscopy (STM) in ultra high vacuum and atomic\nforce microscopy, we investigate the corrugation of graphene flakes deposited\nby exfoliation on a Si/SiO2 (300 nm) surface. While the corrugation on SiO2 is\nlong-range with a correlation length of about 25 nm, some of the graphene\nmonolayers exhibit an additional corrugation with a preferential wave length of\nabout 15 nm. A detailed analysis shows that the long range corrugation of the\nsubstrate is also visible on graphene, but with a reduced amplitude, leading to\nthe conclusion that the graphene is partly freely suspended between hills of\nthe substrate. Thus, the intrinsic rippling observed previously on artificially\nsuspended graphene can exist as well, if graphene is deposited on SiO2."
    },
    {
        "anchor": "Non-equilibrium GW approach to quantum transport in nano-scale contacts: Correlation effects within the GW approximation have been incorporated into\nthe Keldysh non-equilibrium transport formalism. We show that GW describes the\nKondo effect and the zero-temperature transport properties of the Anderson\nmodel fairly well. Combining the GW scheme with density functional theory and a\nWannier function basis set, we illustrate the impact of correlations by\ncomputing the I-V characteristics of a hydrogen molecule between two Pt chains.\nOur results indicate that self-consistency is fundamental for the calculated\ncurrents, but that it tends to wash out satellite structures in the spectral\nfunction.",
        "positive": "The structural and electronic properties of tin oxide nanowires: an {\\it\n  ab initio} investigation: We performed an {\\it ab initio} investigation on the properties of rutile tin\noxide (SnO$_{x}$) nanowires. We computed the wire properties determining the\nequilibrium geometries, binding energies and electronic band structures for\nseveral wire dimensions and surface facet configurations. The results allowed\nto establish scaling laws for the structural properties, in terms of the\nnanowire perimeters. The results also showed that the surface states control\nmost of the electronic properties of the nanowires. Oxygen incorporation in the\nnanowire surfaces passivated the surface-related electronic states, and the\nresulting quantum properties and scaling laws were fully consistent with\nelectrons confined inside the nanowire. Additionally, oxygen incorporation in\nthe wire surfaces generated an unbalanced concentration of spin up and down\nelectrons, leading to magnetic states for the nanowires."
    },
    {
        "anchor": "The effect of isovalent doping on the electronic band structure of group\n  IV semiconductors: The band gap engineering of group IV semiconductors has not been well\nexplored theoretically and experimentally, except for SiGe. Recently, GeSn has\nattracted much attention due to the possibility of obtaining a direct band gap\nin this alloy, thereby making it suitable for light emitters. Other group IV\nalloys may also potentially exhibit material properties useful for device\napplications, expanding the space for band gap engineering in group IV. In this\nwork the electronic band structure of all group IV semiconductor alloys is\ninvestigated. Twelve possible A:B alloys, where A is a semiconducting host (A =\nC, Si, and Ge) and B is an isovalent dopant (B = C, Si, Ge, Sn, and Pb), were\nstudied in the dilute regime (0.8%) of the isovalent dopant in the entire\nBrillouin zone (BZ), and the chemical trends in the evolution of their\nelectronic band structure were carefully analyzed. Density functional theory\nwith state-of-the-art methods such as meta-GGA functionals and a spectral\nweight approach to band unfolding from large supercells was used to obtain\ndopant-related changes in the band structure, in particular the direct band gap\nat the {\\Gamma} point and indirect band gaps at the L(X) points of the BZ.\nAnalysis of contributions from geometry distortion and electronic interaction\nwas also performed. Moreover, the obtained results are discussed in the context\nof obtaining a direct fundamental gap in Ge:B (B = C, Sn, and Pb) alloys, and\nintermediate band formation in C:B (B = Sn and Pb) and Ge:C. An increase in\nlocalization effects is also observed: a strong hole localization for alloys\ndiluted with a dopant of a larger covalent radius and a strong electron\nlocalization for alloys with a dopant of smaller radius. Finally, it is shown\nthat alloying Si and Ge with other elements from group IV is a promising way to\nenhance the functionality of group IV semiconductors.",
        "positive": "2D and 3D cubic monocrystalline and polycrystalline materials: their\n  stability and mechanical properties: We consider 2- and 3-dimensional cubic monocrystalline and polycrystalline\nmaterials. Expressions for Young's and shear moduli and Poisson's ratio are\nexpressed in terms of eigenvalues of the stiffness tensor. Such a form is well\nsuited for studying properties of these mechanical characteristics on sides of\nthe stability triangles. For crystalline high-symmetry directions lines of\nvanishing Poisson's ratio are found. These lines demarcate regions of the\nstability triangle into areas of various auxeticity properties. The simplest\nmodel of polycrystalline 2D and 3D cubic materials is considered. In\npolycrystalline phases the region of complete auxetics is larger than for\nmonocrystalline materials."
    },
    {
        "anchor": "Single-crystal elastic moduli, anisotropy and the B1-B2 phase transition\n  of NaCl at high pressures: Experiment vs. ab-initio calculations: Single-crystal elastic moduli, Cij, and the B1-B2 phase transition of NaCl\nwere investigated experimentally, using time-domain Brillouin scattering\n(TDBS), and theoretically, via density-functional-theory (DFT), to 41 GPa.\nThus, we largely extended pressure range where Cij and elastic anisotropy of\nthe solid are measured, including the first experimental data for the\nhigh-pressure B2 phase, NaCl-B2. NaCl-B1 exhibits a strong and growing with\npressure anisotropy, in contrast to NaCl-B2. Theoretical values obtained using\ndifferent advanced DFT functionals were compared with our measurements but no\none could satisfactorily reproduce our experimental data for NaCl-B1 and\nNaCl-B2 simultaneously. For all available DFT results on the principal shear\nmoduli and anisotropy, the deviation became pronounced when the degree of\ncompression increased significantly. Similar deviations could be also\nrecognized for other cubic solids having the same B1-type structure and similar\nbonding, such as CaO, MgO, or (Mg1-x,Fex)O. Furthermore, the available\nexperimental data suggest that the B1-B2 phase transition of NaCl and the above\nmentioned compounds are governed by the Born stability criterion C44(P) - P >\n0.",
        "positive": "Insightful classification of crystal structures using deep learning: Computational methods that automatically extract knowledge from data are\ncritical for enabling data-driven materials science. A reliable identification\nof lattice symmetry is a crucial first step for materials characterization and\nanalytics. Current methods require a user-specified threshold, and are unable\nto detect average symmetries for defective structures. Here, we propose a\nmachine-learning-based approach to automatically classify structures by crystal\nsymmetry. First, we represent crystals by calculating a diffraction image, then\nconstruct a deep-learning neural-network model for classification. Our approach\nis able to correctly classify a dataset comprising more than 100 000 simulated\ncrystal structures, including heavily defective ones. The internal operations\nof the neural network are unraveled through attentive response maps,\ndemonstrating that it uses the same landmarks a materials scientist would use,\nalthough never explicitly instructed to do so. Our study paves the way for\ncrystal-structure recognition of - possibly noisy and incomplete -\nthree-dimensional structural data in big-data materials science."
    },
    {
        "anchor": "Carrier induced ferromagnetism in concentrated and diluted local-moment\n  systems: For modeling the magnetic properties of concentrated and diluted magnetic\nsemiconductors, we use the Kondo-lattice model. The magnetic phase diagram is\nderived by inspecting the static susceptibility of itinerant band electrons,\nwhich are exchange coupled to localized magnetic moments. It turns out that\nrather low band occupations favour a ferromagnetic ordering of the local moment\nsystems due to an indirect coupling mediated by a spin polarization of the\nitinerant charge carriers. The disorder in diluted systems is treated by adding\na CPA-type concept to the theory. For almost all moment concentrations x,\nferromagnetism is possible, however, only for carrier concentrations n\ndistinctly smaller than x. The charge carrier compensation in real magnetic\nsemiconductors (in Ga_{1-x}Mn_{x}As by e.g. antisites) seems to be a necessary\ncondition for getting carrier induced ferromagnetism.",
        "positive": "Convolutional neural networks enable high-fidelity prediction of\n  path-dependent diffusion barrier spectra in multi-principal element alloys: The emergent multi-principal element alloys (MPEAs) provide a vast\ncompositional space to search for novel materials for technological advances.\nHowever, how to efficiently identify optimal compositions from such a large\ndesign space for targeted properties is a grand challenge in material science.\nHere we developed a convolutional neural network (CNN) model that can\naccurately and efficiently predict path-dependent vacancy migration energy\nbarriers, which are critical to diffusion behaviors and many high-temperature\nproperties, of MPEAs at any compositions and with different chemical\nshort-range orders within a given alloy system. The success of the CNN model\nmakes it promising for developing a database of diffusion barriers for\ndifferent MPEA systems, which would accelerate alloy screening for the\ndiscovery of new compositions with desirable properties. Besides, the length\nscale of local configurations relevant to migration energy barriers is\nuncovered, and the implications of this success to other aspects of materials\nscience are discussed."
    },
    {
        "anchor": "Magnon Accumulation in Chirally Coupled Magnets: We report strong chiral coupling between magnons and photons in microwave\nwaveguides that contain chains of small magnets on special lines. Large magnon\naccumulations at one edge of the chain emerge when exciting the magnets by a\nphased antenna array. This mechanism holds the promise of new functionalities\nin non-linear and quantum magnonics.",
        "positive": "Competing magnetic and spin gap-less semiconducting behaviour in fully\n  compensated ferrimagnet CrVTiAl: Theory and Experiment: We report the structural, magnetic and transport properties of\npolycrystalline CrVTiAl alloy along with first principles calculations. It\ncrystallizes in the LiMgPdSn type structure with lattice parameter 6.14 \\AA\\ at\nroom temperature. Absence of (111) peak along with the presence of a weak (200)\npeak indicates the antisite disorder of Al with Cr and V atoms. The\nmagnetization measurements reveal a ferrimagnetic transition near 710 K and a\ncoercive field of 100 Oe at 3 K. Very low moment and coercive field indicate\nfully compensated ferrimagnetism in the alloy. Temperature coefficient of\nresistivity is found to be negative, indicating a characteristic of\nsemiconducting nature. Absence of exponential dependence of resistivity on\ntemperature indicates a gapless/spin-gapless semiconducting behaviour.\nElectronic and magnetic properties of CrVTiAl for three possible\ncrystallograpic configurations are studied theoretically. All the three\nconfigurations are found to be different forms of semiconductors. Ground state\nconfiguration is a fully compensated ferrimagnet with band gaps 0.58 eV and\n0.30 eV for up and down spin bands respectively. The next higher energy\nconfiguration is also ferrimagnetic, but has spin-gapless semiconducting\nnature. The highest energy configuration corresponds to a non-magnetic gapless\nsemiconductor. The energy differences among these configurations are quite\nsmall ($<$ 1 $\\mathrm{mRy/atom}$) which hints that at finite temperatures, the\nalloy exists in a disordered phase, which is a mixture of the three\nconfigurations. By taking into account the theoretical and the experimental\nfindings, we conclude that CrVTiAl is a fully compensated ferrimagnet with\npredominantly spin gap-less semiconductor nature."
    },
    {
        "anchor": "Large-area synthesis of continuous two-dimensional MoTexSe2-x alloy\n  films by chemical vapor deposition: Great achievements have been made in alloying of two-dimensional (2D)\nsemiconducting transition metal dichalcogenides (TMDs), which can allow tunable\nband gaps for practical applications in optoelectronic devices. However,\ntelluride-based TMDs alloys were less studied due to the difficulties of sample\nsynthesis. Here, in this work we report the large-area synthesis of 2D\nMoTexSe2-x alloy films with controllable Te composition by a modified alkali\nmetal halides assisted chemical vapor deposition method. The as-prepared films\nhave millimeter-scale transverse size. Raman spectra experiments combining\ncalculated Raman spectra and vibrational images obtained by density functional\ntheory (DFT) confirmed the 2H-phase of the MoTexSe2-x alloys. The A1g mode of\nMoSe2 shows a significant downshift accompanied by asymmetric broadening to\nlower wavenumber with increasing value of x, while E12g mode seems unchanged,\nwhich were well explained by a phonon confinement model. Our work provides a\nsimple method to synthesize large-scale 2H phase Te-based 2D TMDs alloys for\ntheir further applications.",
        "positive": "Counterintuitive strain distribution in axial (In,Ga)N/GaN nanowires: We study the three-dimensional deformation field induced by an axial (In,Ga)N\nsegment in a GaN nanowire. Using the finite element method within the framework\nof linear elasticity theory, we study the dependence of the strain field on the\nratio of segment length and nanowire radius. Contrary to intuition, the\nout-of-plane-component of the elastic strain tensor is found to assume large\nnegative values for a length-to-radius ratio close to one. We show that this\nunexpected effect is a direct consequence of the deformation of the nanowire at\nthe free sidewalls and the associated large shear strain components. Simulated\nreciprocal space maps of a single (In,Ga)N/GaN nanowire demonstrate that\nnanofocus x-ray diffraction is a suitable technique to assess this peculiar\nstrain state experimentally."
    },
    {
        "anchor": "Weak antilocalization and zero-field electron spin splitting in\n  AlGaN/AlN/GaN heterostructures with a polarization induced two-dimensional\n  electron gas: Spin-orbit coupling is studied using the quantum interference corrections to\nconductance in AlGaN/AlN/GaN two-dimensional electron systems where the carrier\ndensity is controlled by the persistent photoconductivity effect. All the\nsamples studied exhibit a weak antilocalization feature with a spin-orbit field\nof around 1.8 mT. The zero-field electron spin splitting energies extracted\nfrom the weak antilocalization measurements are found to scale linearly with\nthe Fermi wavevector with an effective linear spin-orbit coupling parameter\n5.5x10^{-13} eV m. The spin-orbit times extracted from our measurements varied\nfrom 0.74 to 8.24 ps within the carrier density range of this experiment.",
        "positive": "Ab initio theory of free-carrier absorption in semiconductors: The absorption of light by free carriers in semiconductors results in optical\nloss for all photon wavelengths. Since free-carrier absorption competes with\noptical transitions across the band gap, it also reduces the efficiency of\noptoelectronic devices such as solar cells because it does not generate\nelectron-hole pairs. In this work, we develop a first-principles theory of\nfree-carrier absorption taking into account both single-particle excitations\nand the collective Drude term, and we demonstrate its application to the case\nof doped Si. We determine the free-carrier absorption coefficient as a function\nof carrier concentration and we obtain excellent agreement with experimental\ndata. We identify the dominant processes that contribute to free-carrier\nabsorption at various photon wavelengths, and analyze the results to evaluate\nthe impact of this loss mechanism on the efficiency of Si-based optoelectronic\ndevices."
    },
    {
        "anchor": "Tetravalent doping of CeO$_2$: The impact of valence electron character\n  on group IV dopant influence: Fluorite CeO$_2$ doped with group IV elements is studied within the DFT and\nDFT+U framework. Concentration dependent formation energies are calculated for\nCe$_{1-x}$Z$_x$O$_2$ (Z= C, Si, Ge, Sn, Pb, Ti, Zr, Hf) with $0\\leq x \\leq\n0.25$ and a roughly decreasing trend with ionic radius is observed. The\ninfluence of the valence and near valence electronic configuration is\ndiscussed, indicating the importance of filled $d$ and $f$ shells near the\nFermi level for all properties investigated. A clearly different behavior of\ngroup IVa and IVb dopants is observed: the former are more suitable for surface\nmodifications, the latter are more suitable for bulk modifications.\\\\ \\indent\nFor the entire set of group IV dopants, there exists an inverse relation\nbetween the change, due to doping, of the bulk modulus and the thermal\nexpansion coefficients. Hirshfeld-I atomic charges show that charge transfer\neffects due to doping are limited to the nearest neighbor oxygen atoms.",
        "positive": "Optical properties of Fe-Mn-Ga alloys: The first-principles calculations of the electronic structures and the\ninterband optical conductivity (OC) spectra have been performed for the\nstoichiometric Fe$_{2}$MnGa alloy with L2$_{1}$ and L1$_{2}$ types of atomic\nordering. The calculated optical properties of Fe$_{2}$MnGa alloy for the\nL2$_{1}$ and L1$_{2}$ phases are complemented by the experimental OC spectra\nfor bulk and thin film Fe-Mn-Ga alloy samples near the stoichiometry 2:1:1 with\nL2$_{1}$ and L1$_{2}$ (for bulks) as well as the body-centered-cubic and\nface-centered-cubic (for films) structures, respectively. A reasonable\nagreement between experimental and calculated interband OC spectra was obtained\nfor both phases of the alloy. The experimental data show no significant\ndifference in the OC spectra with respect to the degrees of atomic and magnetic\norders of the samples."
    },
    {
        "anchor": "Strong electron-phonon coupling in delta-phase stabilized Pu: Heat capacity measurements of the delta-phase stabilized alloy Pu-Al suggest\nthat strong electron-phonon coupling is required to explain the moderate\nrenormalization of the electronic density of states near the Fermi energy. We\ncalculate the heat capacity contributions from the lattice and electronic\ndegrees of freedom as well as from the electron-lattice coupling term and find\ngood overall agreement between experiment and theory assuming a dimensionless\nelectron-phonon coupling parameter of order unity, lambda ~ 0.8. This large\nelectron-phonon coupling parameter is comparable to reported values in other\nsuperconducting metals with face-centered cubic crystal structure, for example,\nPd (lambda ~ 0.7) and Pb (lambda ~ 1.5). Further, our analysis shows evidence\nof a sizable residual low-temperature entropy contribution, S_{res} ~ 0.4 k_B\n(per atom). We can fit the residual specific heat to a two-level system.\nTherefore, we speculate that the observed residual entropy originates from\ncrystal-electric field effects of the Pu atoms or from self-irradiation induced\ndefects frozen in at low temperatures.",
        "positive": "A gravity-independent powder-based additive manufacturing process\n  tailored for space applications: The future of space exploration missions will rely on technologies increasing\ntheir endurance and self-sufficiency, including for manufacturing objects\non-demand. We propose a process for handling and additively manufacturing\npowders that functions independently of the gravitational environment and with\nno restriction on feedstock powder flowability. Based on a specific sequence of\nboundary loads applied to the granular packing, powder is transported to the\nprinting zone, homogenized and put under compression to increase the density of\nthe final part. The powder deposition process is validated by simulations that\nshow the homogeneity and density of deposition to be insensitive to gravity and\ncohesion forces within the DEM model. We further provide an experimental proof\nof concept of the process by successfully 3D printing parts on-ground and in\nweightlessness, on parabolic flight. Powders exhibiting high and low\nflowability are used as model feedstock material to demonstrate the versatility\nof the process, opening the way for additive manufacturing of recycled\nmaterial."
    },
    {
        "anchor": "Thickness evolution of coercivity in ultrathin magnetic films: The thickness evolution of in-plane magnetization reversal in ultrathin films\nis studied with a theoretical model that takes account of surface roughness\ntypical of epitaxial growth. Guided by N\\'{e}el's model, step edge sites of\nmonolayer-height islands are assigned a two-fold anisotropy in addition to a\nfour-fold anisotropy at all sites. Coercivity is found to depend essentially on\nboth the film thickness and the partial coverage of the topmost layer. Its\nqualitative features are determined primarily by sample geometry and the size\nof the step anisotropy compared to the domain wall energy. Magnetostatic\ninteractions change the results quantitatively, but not qualitatively. Their\neffect is understood by comparing calculations with and without their\ninclusion.",
        "positive": "On the Formation of Thin Ice Crystal Plates: A New Type of Morphological\n  Instability in Diffusion-Limited Growth: We propose a new type of morphological instability in the diffusion-limited\ngrowth of faceted crystals from the vapor phase that can explain the formation\nof thin ice plates at temperatures near -15 C. The instability appears when the\nattachment kinetics for facet growth depends strongly on the morphology of the\nfacet surface. In particular, we propose that the condensation coefficient for\ngrowth of ice prism facets increases dramatically when the width of the facet\napproaches atomic dimensions. This model reconciles several conflicting\nmeasurements of ice crystal growth, and makes additional predictions for future\ngrowth experiments. Other faceted crystalline materials may exhibit similar\nmorphological instabilities that promote the diffusion-limited growth of thin\nplate-like or needle-like crystal structures."
    },
    {
        "anchor": "Immunity to Scaling in MoS2 Transistors Using Edge Contacts: Atomically thin two-dimensional (2D) materials are promising candidates for\nsub-10 nm transistor channels due to their ultrathin body thickness, which\nresults in strong electrostatic gate control. Properly scaling a transistor\ntechnology requires reducing both the channel length (distance from source to\ndrain) and the contact length (distance that source and drain interface with\nsemiconducting channel). Contact length scaling remains an unresolved epidemic\nfor transistor scaling, affecting devices from all semiconductors, from silicon\nto 2D materials. Here, we show that clean edge contacts to 2D MoS2 provide\nimmunity to the contact-scaling problem, with performance that is independent\nof contact length down to the 20 nm regime. Using a directional ion beam, in\nsitu edge contacts of various metal-MoS2 interfaces are studied.\nCharacterization of the intricate edge interface using cross-sectional electron\nmicroscopy reveals distinct morphological effects on the MoS2 depending on its\nthickness, from monolayer to few-layer films. Chromium is found to outperform\nother metals in the edge contact scheme, which is attributed to the shorter\nCr-MoS2 bond length. Compared to scaled top contacts with 20 nm contact length,\nin situ edge contacts yield better performance with an effective contact length\nof ~ 1 nm and 18 times higher carrier injection efficiency. The in situ edge\ncontacts also exhibit ~8 times higher performance compared to the best-reported\nedge contacts. Our work provides experimental evidence for a solution to\ncontact scaling in transistors, using 2D materials with clean edge contact\ninterfaces, opening a new way of designing devices with 2D materials.",
        "positive": "Phase transition of chemically doped uniaxial relaxor ferroelectric: We report a neutron scattering study of the ferroelectric phase transition in\nSr$_{0.585}$Ce$_{0.025}$Ba$_{0.39}$Nb$_2$O$_6$ (SBN-61:Ce). We find no evidence\nfor a soft transverse optic phonon. We do, however, observe anisotropic diffuse\nscattering. This scattering has inelastic and elastic contributions. In the\nparaelectric phase the susceptibility associated with the elastic diffuse\nscattering follows well the anomaly of the dielectric susceptibility of\nSBN-61:Ce. In the ferroelectric phase the lineshape of the elastic scattering\nis consistent with the form expected for the ferroelectric domain walls. In\ncontrast to the macroscopic observations, the scattering properties of Ce-doped\ncrystal do not exhibit important changes with respect to those of pure\nSr$_{0.61}$Ba$_{0.39}$Nb$_2$O$_6$."
    },
    {
        "anchor": "A discrete model and analysis of one dimensional deformations in a\n  structural interface with micro-rotations: The static and dynamic properties of a Cosserat-type lattice interface of\nfinite thickness are studied, so that both displacements and rotational degrees\nof freedom are taken into account. The model allows considering interfaces with\na beam-like microstructure and interfaces with finite size particles as\nparticular cases. One-dimensional solutions describing shear and\nmicro-rotations at the interface are obtained and discussed. Harmonic as well\nas localized solutions, and the properties of the interfaces as filters for\nelastic waves are investigated. It is shown that both systems with long- and\nshort-wavelength localization may exist.",
        "positive": "Visualizing half-metallic bulk band structure with multiple Weyl cones\n  of the Heusler ferromagnet: Using a well-focused soft X-ray synchrotron radiation beam, angle-resolved\nphotoelectron spectroscopy was applied to a full-Heusler-type Co$_2$MnGe alloy\nto elucidate its bulk band structure. A large parabolic band at the Brillouin\nzone center and several bands that cross the Fermi level near the Brillouin\nzone boundary were identified in line with the results from first-principles\ncalculations. These Fermi level crossings are ascribed to majority spin bands\nthat are responsible for electron transport with extremely high spin\npolarization especially along the direction being perpendicular to the\ninterface of magneto-resistive devices. The spectroscopy confirms there is no\ncontribution of the minority spin bands to the Fermi surface, signifying\nhalf-metallicity for the alloy. Furthermore, two topological Weyl cones with\nband crossing points were identified around the $X$ point, yielding the\nconclusion that Co$_2$MnGe could exhibit topologically meaningful behavior such\nas large anomalous Hall and Nernst effects driven by the Berry flux in its\nhalf-metallic band structure."
    },
    {
        "anchor": "Quantitative analysis of MoS$_2$ thin film micrographs with machine\n  learning: Isolating the features associated with different materials growth conditions\nis important to facilitate the tuning of these conditions for effective\nmaterials growth and characterization. This study presents machine learning\nmodels for classifying atomic force microscopy (AFM) images of thin film\nMoS$_2$ based on their growth temperatures. By employing nine different\nalgorithms and leveraging transfer learning through a pretrained ResNet model,\nwe identify an effective approach for accurately discerning the characteristics\nrelated to growth temperature within the AFM micrographs. Robust models with up\nto 70% test accuracies were obtained, with the best performing algorithm being\nan end-to-end ResNet fine-tuned on our image domain. Class activation maps and\nocclusion attribution reveal that crystal quality and domain boundaries play\ncrucial roles in classification, with models exhibiting the ability to identify\nlatent features beyond human visual perception. Overall, the models\ndemonstrated high accuracy in identifying thin films grown at different\ntemperatures despite limited and imbalanced training data as well as variation\nin growth parameters besides temperature, showing that our models and training\nprotocols are suitable for this and similar predictive tasks for accelerated 2D\nmaterials characterization.",
        "positive": "Sharp-Interface Limit of a Fluctuating Phase-Field Model: We present a derivation of the sharp-interface limit of a generic fluctuating\nphase-field model for solidification. As a main result, we obtain a\nsharp-interface projection which presents noise terms in both the diffusion\nequation and in the moving boundary conditions. The presented procedure does\nnot rely on the fluctuation-dissipation theorem, and can therefore be applied\nto account for both internal and external fluctuations in either variational or\nnon-variational phase-field formulations. In particular, it can be used to\nintroduce thermodynamical fluctuations in non-variational formulations of the\nphase-field model, which permit to reach better computational efficiency and\nprovide more flexibility for describing some features of specific physical\nsituations. This opens the possibility of performing quantitative phase-field\nsimulations in crystal growth while accounting for the proper fluctuations of\nthe system."
    },
    {
        "anchor": "Evidence for coincidence of Kauzmann temperature and liquid-liquid\n  transition temperature in supercooled silicon: The paper is withdrawn.",
        "positive": "Trampoline metamaterial: Local resonance enhancement by springboards: We investigate the dispersion characteristics of locally resonant elastic\nmetamaterials formed by the erection of pillars on the solid regions in a plate\npatterned by a periodic array of holes. We show that these solid regions\neffectively act as springboards leading to an enhanced resonance behavior by\nthe pillars when compared to the nominal case of pillars with no holes. This\nlocal resonance amplification phenomenon, which we define as the \"trampoline\neffect\", is shown to cause subwavelength band gaps to increase in size by up to\na factor of 4. This outcome facilitates the utilization of subwavelength\nmetamaterial properties over exceedingly broad frequency ranges."
    },
    {
        "anchor": "Ab initio calculations of phonon spectra in ATiO3 perovskite crystals (A\n  = Ca, Sr, Ba, Ra, Cd, Zn, Mg, Ge, Sn, Pb): The phonon spectra of calcium, strontium, barium, radium, cadmium, zinc,\nmagnesium, germanium, tin, and lead titanates with the perovskite structure are\ncalculated from first principles within the density functional theory. By\nanalyzing the unstable modes in the phonon spectra, the possible lattice\ndistortions are determined and the energies of the corresponding phases are\ncalculated. From analyzing the phonon spectra, force constants, and\neigenvectors of TO phonons, a conclusion is drawn on the origin of the\nferroelectricity in considered crystals. It is shown that the main factors\ndetermining the possible off-centering of atoms in the A position are the\ngeometric size and electronic configuration of these atoms.",
        "positive": "Formation of grains and dislocation structure of geometrically necessary\n  boundaries: A continuum dislocation model of formation of grains whose boundaries have a\nnon-vanishing thickness is proposed. For a single crystal deforming in simple\nshear the lamellar structure of grains with thin layers containing dislocations\nas the geometrically necessary boundaries turns out to be energetically\npreferable. The thickness and the energy of this type of grain boundary are\ncomputed as functions of the misorientation angle."
    },
    {
        "anchor": "Database Construction for Two-Dimensional Material-Substrate Interfaces: The interfacial structures and interactions of two-dimensional (2D) materials\non solid substrates are of fundamental importance for the fabrication and\napplication of 2D materials. However, selection of a suitable solid substrate\nto grow 2D material, determination and control of the 2D material-substrate\ninterface remain a big challenge due to the large diversity of possible\nconfigurations. Here, we propose a computational framework to select an\nappropriate substrate for epitaxial growth of 2D material and to predict\npossible 2D material-substrate interface structures and orientations using\ndensity functional theory calculations performed for all non-equivalent atomic\nstructures satisfying the symmetry constraints. The approach was validated by\nthe correct prediction of three experimentally reported 2D material-substrate\ninterface systems with only the given information of two parent materials.\nSeveral possible interface configurations are also proposed based on this\napproach. We therefore construct a database that contains these interface\nsystems and has been continuously expanding. This database serves as\npreliminary guidance for epitaxial growth and stabilization of new materials in\nexperiments.",
        "positive": "EXAFS Experiments on Local Structure of NO Adsorbed on Supported Silver\n  Clusters: In-situ EXAFS experiments were performed at the Ag $K$-edge after adsorbing\nNO on the hydrogen reduced silver cluster. The coordination parameters, i.e.\ninter-atomic distance, coordination number and Debye-Waller factor were derived\nfrom a three-shell fitting model including a split Ag-Ag shell and a single\nAg-O(N) shell. The multiple-shell fitting proved that the reduced silver\ncluster underwent a slight change in the local structure. After co-adsorbing NO\nand oxygen, the difference file fitting technique was used for isolating each\nof the first Ag-Ag(1) and Ag-O(N) shell contributions to the EXAFS spectra\nfiltered in R-space of Fourier transform."
    },
    {
        "anchor": "Study of the Electron Mobility in InAs/GaSb Type II Superlattices at\n  High Temperatures: In this paper, we present a study of the effects of temperature on the\nelectron mobility in InAs/GaSb type-II superlattices (SLs) in which the band\nstructures and wave functions are calculated by solving the K.P Hamiltonian\nusing the numerical Finite Difference method. In the model the dominant\nscattering mechanisms such as alloy scattering, acoustic phonon scattering and\noptical phonon scattering are taken into account. The obtained electron\nmobility of the type II SLs is depended on the structural parameters and\ndifferent scattering parameters. A comparison of our calculated results with\npublished experimental data is shown to be in good agreement.",
        "positive": "Ion exchange in atomically thin clays and micas: Clays and micas are receiving attention as materials that, in their\natomically thin form, could allow for novel proton conductive, ion selective,\nosmotic power generation, or solvent filtration membranes. The interest arises\nfrom the possibility of controlling their properties by exchanging ions in the\ncrystal lattice. However, the ion exchange process itself remains largely\nunexplored in atomically thin materials. Here we use atomic-resolution scanning\ntransmission electron microscopy to study the dynamics of the process and\nreveal the binding sites of individual ions in atomically thin and artificially\nrestacked clays and micas. Imaging ion exchange after different exposure time\nand for different crystal thicknesses, we find that the ion diffusion constant,\nD, for the interlayer space of atomically thin samples is up to 10^4 times\nlarger than in bulk crystals and approaches its value in free water.\nSurprisingly, samples where no bulk exchange is expected display fast exchange\nif the mica layers are twisted and restacked; but in this case, the exchanged\nions arrange in islands controlled by the moir\\'e superlattice dimensions. We\nattribute the fast ion diffusion to enhanced interlayer expandability resulting\nfrom weaker interlayer binding forces in both atomically thin and restacked\nmaterials. Finally, we demonstrate images of individual surface cations for\nthese materials, which had remained elusive in previous studies. This work\nprovides atomic scale insights into ion diffusion in highly confined spaces and\nsuggests strategies to design novel exfoliated clays membranes."
    },
    {
        "anchor": "Rippling of Graphene: Meyer et al (2007) found that free-standing graphene sheets, just one atom\nthick, display spontaneous ripples. The ripples are of order 2-20 {\\AA} high\nand 20-200 {\\AA} wide. The sheets in which they appear are only one atom thick,\nand extend for around 5000 {\\AA} through vacuum between metal struts that\nsupport them. Other groups have since created free-standing graphene as well\n(Garcia-Sanchez 2008 ; Bolotin et al. 2008), and similar ripples have been\nfound for graphene on a glass substrate (Geringer et al. 2008). Here we show\nthat these ripples can be explained as a consequence of adsorbed molecules\nsitting on random sites. The adsorbates cause the bonds between carbon atoms to\nlengthen slightly. Static buckles then result from a mechanism like the one\nthat leads to buckling of leaves; buckles caused by roughly 20% coverage of\nadsorbates are consistent with experimental observations. We explain why this\nmechanism is more likely to explain rippled than thermal fluctuations or the\nMermin-Wagner theorem, which have previously been invoked.",
        "positive": "Out- versus in-plane magnetic anisotropy of free Fe and Co nanocrystals:\n  tight-binding and first-principles studies: We report tight-binding (TB) and Density Function Theory (DFT) calculations\nof magnetocrystalline anisotropy energy (MAE) of free Fe (body centerd cubic)\nand Co (face centered cubic) slabs and nanocrystals. The nanocrystals are\ntruncated square pyramids which can be obtained experimentally by deposition of\nmetal on a SrTiO$_3$(001) substrate. For both elements our local analysis shows\nthat the total MAE of the nanocrystals is largely dominated by the contribution\nof (001) facets. However, while the easy axis of Fe(001) is out-of-plane, it is\nin-plane for Co(001). This has direct consequences on the magnetic reversal\nmechanism of the nanocrystals. Indeed, the very high uniaxial anisotropy of Fe\nnanocrystals makes them a much better potential candidate for magnetic storage\ndevices."
    },
    {
        "anchor": "Depth profile photoemission study of thermally diffused Mn/GaAs (001)\n  interfaces: We have performed a depth profile study of thermally diffused Mn/GaAs (001)\ninterfaces using photoemission spectroscopy combined with Ar$^+$-ion\nsputtering. We found that Mn ion was thermally diffused into the deep region of\nthe GaAs substrate and completely reacted with GaAs. In the deep region, the Mn\n2$p$ core-level and Mn 3$d$ valence-band spectra of the Mn/GaAs (001) sample\nheated to 600 $^{\\circ}$C were similar to those of Ga$_{1-x}$Mn$_x$As,\nzinc-blende-type MnAs dots, and/or interstitial Mn in tetrahedrally coordinated\nby As atoms, suggesting that the Mn 3$d$ states were essentially localized but\nwere hybridized with the electronic states of the host GaAs. Ferromagnetism was\nobserved in the dilute Mn phase.",
        "positive": "Ultra-large tensile strains and martensite destabilization observed in\n  high-temperature Ni57.5Mn22.5Ga20.0 single crystal: Tensile stress-strain behavior of Ni57.5Mn22.5Ga20.0 single crystal\nexhibiting a high-temperature 2M-martensitic phase stable up to 360\\degree C\nhas been studied in the course of thermal and mechanical cycling. The\nultra-large reversible strains, about 9%, caused by the shape memory and\nsuperelasticity effects, have been observed up to 400 \\degree C being the\ninstrumental temperature limit. Abnormally large two-way shape memory effect\nwith 9% of strain magnitude has been found. The cycling procedure and the\nvariation of thermal/mechanical routs of the training of samples revealed the\ndestabilization (rejuvenation) of martensite. This physical effect is opposite\nto the well-known phenomenon of martensite stabilization. A destabilization\neffect is explained phenomenologically in terms of internal stressing of the\nalloy sample by the crystal defects."
    },
    {
        "anchor": "Interface Response Functions for multicomponent alloy solidification- An\n  application to additive manufacturing: The near-rapid solidification conditions during additive manufacturing can\nlead to selection of non-equilibrium phases. Sharp interface models via\ninterface response functions have been used earlier to explain the\nmicrostructure selection under such solidification conditions. However, most of\nthe sharp interface models assume linear superposition of contributions of\nalloying elements without considering the non-linearity associated with the\nphase diagram. In this report, both planar and dendritic Calphad coupled sharp\ninterface models have been implemented and used to explain the\ngrowth-controlled phase selection observed at high solidification velocities\nrelevant to additive manufacturing. The implemented model predicted the\ngrowth-controlled phase selection in multicomponent alloys, which the other\nmodels with linear phase diagram could not. These models are calculated for\nsteels and a Nickel-based superalloy and the results are compared with\nexperimental observations.",
        "positive": "Faraday-cage screening reveals intrinsic aspects of the van der Waals\n  attraction: General properties of the recently observed screening of the van der Waals\n(vdW) attraction between a silica substrate and silica tip by insertion of\ngraphene are predicted using basic theory and first-principles calculations.\nResults are then focused on possible practical applications, as well as an\nunderstanding of the nature of vdW attraction, considering recent discoveries\nshowing it competing against covalent and ionic bonding. The traditional view\nof the vdW attraction as arising from pairwise-additive London dispersion\nforces is considered using Grimme's \"D3\" method, comparing results to those\nfrom Tkatchenko's more general many-body dispersion (MBD) approach, all\ninterpreted in terms of Dobson's general dispersion framework. Encompassing the\nexperimental results, MBD screening of the vdW force between two silica\nbilayers is shown to scale up to medium separations as 1.25 de/d, where d is\nthe bilayer separation and de its equilibrium value, depicting antiscreening\napproaching and inside de. Means of unifying this correlation effect with those\nincluded in modern density functionals are urgently required."
    },
    {
        "anchor": "Image charge screening: a new approach to enhance magnetic ordering\n  temperatures: We have tested the concept of image charge screening as a new approach to\nenhance magnetic ordering temperatures and superexchange interactions in ultra\nthin films. Using a 3 monolayer NiO(100) film grown on Ag(100) and an\nidentically thin film on MgO(100) as model systems, we observed that the Neel\ntemperature of the NiO film on the highly polarizable metal substrate is 390 K\nwhile that of the film on the poorly polarizable insulator substrate is below\n40 K. This demonstrates that screening by highly polarizable media may point to\na practical way towards designing strongly correlated oxide nanostructures with\ngreatly improved magnetic properties.",
        "positive": "Co$_2$FeAl full Heusler compound based spintronic terahertz emitter: To achieve a large terahertz (THz) amplitude from a spintronic THz emitter\n(STE), materials with 100\\% spin polarisation such as Co-based Heusler\ncompounds as the ferromagnetic layer are required. However, these compounds are\nknown to loose their half-metallicity in the ultrathin film regime, as it is\ndifficult to achieve L2$_1$ ordering, which has become a bottleneck for the\nfilm growth. Here, the successful deposition using room temperature DC\nsputtering of the L2$_1$ and B2 ordered phases of the Co$_2$FeAl full Heusler\ncompound is reported. Co$_2$FeAl is used as ferromagnetic layer together with\nhighly orientated Pt as non-ferromagnetic layer in the Co$_2$FeAl/Pt STE, where\nan MgO(10 nm) seed layer plays an important role to achieve the L2$_1$ and B2\nordering of Co$_2$FeAl. The generation of THz radiation in the CFA/Pt STE is\npresented, which has a bandwidth in the range of 0.1-4 THz. The THz electric\nfield amplitude is optimized with respect to thickness, orientation, and growth\nparameters using a thickness dependent model considering the optically induced\nspin current, superdiffusive spin current, inverse spin Hall effect and the\nattenuation of THz radiation in the layers. This study, based on the full\nHeusler Co$_2$FeAl compound opens up a plethora possibilities in STE research\ninvolving full Heusler compounds."
    },
    {
        "anchor": "Valence-band mixing in first-principles envelope-function theory: This paper presents a numerical implementation of a first-principles\nenvelope-function theory derived recently by the author [B. A. Foreman, Phys.\nRev. B 72, 165345 (2005)]. The examples studied deal with the valence subband\nstructure of GaAs/AlAs, GaAs/Al(0.2)Ga(0.8)As, and In(0.53)Ga(0.47)As/InP (001)\nsuperlattices calculated using the local density approximation to\ndensity-functional theory and norm-conserving pseudopotentials without\nspin-orbit coupling. The heterostructure Hamiltonian is approximated using\nquadratic response theory, with the heterostructure treated as a perturbation\nof a bulk reference crystal. The valence subband structure is reproduced\naccurately over a wide energy range by a multiband envelope-function\nHamiltonian with linear renormalization of the momentum and mass parameters.\nGood results are also obtained over a more limited energy range from a\nsingle-band model with quadratic renormalization. The effective kinetic-energy\noperator ordering derived here is more complicated than in many previous\nstudies, consisting in general of a linear combination of all possible operator\norderings. In some cases the valence-band Rashba coupling differs significantly\nfrom the bulk magnetic Luttinger parameter. The splitting of the\nquasidegenerate ground state of no-common-atom superlattices has non-negligible\ncontributions from both short-range interface mixing and long-range dipole\nterms in the quadratic density response.",
        "positive": "Thru-Hole Epitaxy: Is Remote Epitaxy Really Remote?: The remote epitaxy was originally proposed to grow a film, which is not in\ncontact but crystallographically aligned with a substrate and easily detachable\ndue to a van der Waals material as a space layer. Here we show that the claimed\nremote epitaxy is more likely to be nonremote `thru-hole' epitaxy. On a\nsubstrate with thick and symmetrically incompatible van der Waals space layer\nor even with a three-dimensional amorphous oxide film in-between, we\ndemonstratively grew GaN domains through thru-holes via connectedness-initiated\nepitaxial lateral overgrowth, not only readily detachable but also\ncrystallographically aligned with a substrate. Our proposed nonremote thru-hole\nepitaxy, which is embarrassingly straightforward and undemanding, can provide\nwider applicability of the benefits known to be only available by the claimed\nremote epitaxy."
    },
    {
        "anchor": "Self-consistent GW: All-electron implementation with localized basis\n  functions: This paper describes an all-electron implementation of the self-consistent GW\n(sc-GW) approach -- i.e. based on the solution of the Dyson equation -- in an\nall-electron numeric atom-centered orbital (NAO) basis set. We cast Hedin's\nequations into a matrix form that is suitable for numerical calculations by\nmeans of i) the resolution of identity technique to handle 4-center integrals;\nand ii) a basis representation for the imaginary-frequency dependence of\ndynamical operators. In contrast to perturbative G0W0, sc-GW provides a\nconsistent framework for ground- and excited-state properties and facilitates\nan unbiased assessment of the GW approximation. For excited-states, we\nbenchmark sc-GW for five molecules relevant for organic photovoltaic\napplications: thiophene, benzothiazole, 1,2,5-thiadiazole, naphthalene, and\ntetrathiafulvalene. At self-consistency, the quasi-particle energies are found\nto be in good agreement with experiment and, on average, more accurate than\nG0W0 based on Hartree-Fock (HF) or density-functional theory with the\nPerdew-Burke-Ernzerhof (PBE) exchange-correlation functional. Based on the\nGalitskii-Migdal total energy, structural properties are investigated for a set\nof diatomic molecules. For binding energies, bond lengths, and vibrational\nfrequencies sc-GW and G0W0 achieve a comparable performance, which is, however,\nnot as good as that of exact-exchange plus correlation in the random-phase\napproximation (EX+cRPA) and its advancement to renormalized second-order\nperturbation theory (rPT2). Finally, the improved description of dipole moments\nfor a small set of diatomic molecules demonstrates the quality of the sc-GW\nground state density.",
        "positive": "Electronic and Thermoelectric Properties of Few-Layer Transition Metal\n  Dichalcogenides: The electronic and thermoelectric properties of one to four monolayers of\nMoS$_{2}$, MoSe$_{2}$, WS$_{2}$, and WSe$_{2}$ are calculated. For few layer\nthicknesses,the near degeneracies of the conduction band $K$ and $\\Sigma$\nvalleys and the valence band $\\Gamma$ and $K$ valleys enhance the n-type and\np-type thermoelectric performance. The interlayer hybridization and energy\nlevel splitting determine how the number of modes within $k_BT$ of a valley\nminimum changes with layer thickness. In all cases, the maximum ZT coincides\nwith the greatest near-degeneracy within $k_BT$ of the band edge that results\nin the sharpest turn-on of the density of modes. The thickness at which this\nmaximum occurs is, in general, not a monolayer. The transition from few layers\nto bulk is discussed. Effective masses, energy gaps, power-factors, and ZT\nvalues are tabulated for all materials and layer thicknesses."
    },
    {
        "anchor": "First-principles characterization of ferromagnetism in N-doped SrTiO3\n  and BaTiO3: The spin-polarization and magnetic coupling character of N-doped SrTiO3 and\nBaTiO3 are studied through first-principles calculations. The substitutional N\ndoping at O sites leads to a half-metallic property and produces a magnetic\nmoment of 1.0 {\\mu}B. The magnetic interaction between the nearest and\nnext-nearest N dopants results in a strong ferromagnetic coupling. When the\ndistance between the N dopants is larger than 7 {\\AA}, the ground state of the\nsystem tends to be paramagnetic. A nitrogen-concentration threshold to produce\nthe ferromagnetism is estimated. The calculated results give a good explanation\nfor the experimentally observed ferromagnetism in N-doped SrTiO3 and BaTiO3.",
        "positive": "The optical properties of transferred graphene and the dielectrics grown\n  on it obtained by ellipsometry: Graphene layers grown by chemical vapour deposition (CVD) method and\ntransferred from Cu-foils to the oxidized Si-substrates were investigated by\nspectroscopic ellipsometry (SE), Raman and X-Ray Photoelectron Spectroscopy\n(XPS) methods. The optical properties of transferred CVD graphene layers do not\nalways correspond to the ones of the exfoliated graphene due to the\ncontamination from the chemicals used in the transfer process. However, the\nreal thickness and the mean properties of the transferred CVD graphene layers\ncan be found using ellipsometry if a real thickness of the SiO2 layer is taken\ninto account. The pulsed layer deposition (PLD) and atomic layer deposition\n(ALD) methods were used to grow dielectric layers on the transferred graphene\nand the obtained structures were characterized using optical methods. The\napproach demonstrated in this work could be useful for the characterization of\nvarious materials grown on graphene."
    },
    {
        "anchor": "Pressure-induced phase transition in Bi$_2$Se$_3$ at 3 GPa: electronic\n  topological transition or not?: In recent years, a low pressure transition around P $\\sim$ 3 GPa exhibited by\nthe A$_2$B$_3$-type 3D topological insulators is attributed to an electronic\ntopological transition (ETT) for which there is no direct evidence either from\ntheory or experiments. We address this phase transition and other transitions\nat higher pressure in bismuth selenide (Bi$_2$Se$_3$) using Raman spectroscopy\nat pressure upto 26.2 GPa. We see clear Raman signatures of an isostructural\nphase transition at P $\\sim$ 2.4 GPa followed by structural transitions at\n$\\sim$ 10 GPa and 16 GPa. First-principles calculations reveal anomalously\nsharp changes in the structural parameters like the internal angle of the\nrhombohedral unit cell with a minimum in the c/a ratio near P $\\sim$ 3 GPa.\nWhile our calculations reveal the associated anomalies in vibrational\nfrequencies and electronic bandgap, the calculated $\\mathbb{Z}_2$ invariant and\nDirac conical surface electronic structure remain unchanged, showing that there\nis no change in the electronic topology at the lowest pressure transition.",
        "positive": "First-principles anharmonic vibrational study of the structure of\n  calcium silicate perovskite under lower mantle conditions: Calcium silicate perovskite (CaSiO$_3$) is one of the major mineral\ncomponents of the lower mantle, but has been the subject of relatively little\nwork compared to the more abundant Mg-based materials. One of the major\nproblems related to CaSiO$_3$ that is still the subject of research is its\ncrystal structure under lower mantle conditions - a cubic Pm$\\bar{3}$m\nstructure is accepted in general, but some have suggested that lower-symmetry\nstructures may be relevant. In this paper, we use a fully first-principles\nvibrational self-consistent field method to perform high accuracy anharmonic\nvibrational calculations on several candidate structures at a variety of points\nalong the geotherm near the base of the lower mantle to investigate the\nstability of the cubic structure and related distorted structures. Our results\nshow that the cubic structure is the most stable throughout the lower mantle,\nand that this result is robust against the effects of thermal expansion."
    },
    {
        "anchor": "Kondo holes in the 2D itinerant Ising ferromagnet Fe3GeTe2: Heavy fermion (HF) states emerge in correlated quantum materials due to the\ninterplay between localized magnetic moments and itinerant electrons, but\nrarely appear in 3d-electron systems due to high itinerancy of d-electrons.\nHere, an anomalous enhancement of Kondo screening is observed at the Kondo hole\nof local Fe vacancies in Fe3GeTe2 which is a recently discovered 3d-HF system\nfeaturing of Kondo lattice and two-dimensional itinerant ferromagnetism. An\nitinerant Kondo-Ising model is established to reproduce the experimental\nresults which provides insight of the competition between Ising ferromagnetism\nand Kondo screening. This work explains the microscopic origin of the\nd-electron HF states and inspires study of the enriched quantum many-body\nphenomena with Kondo holes in Ising ferromagnets.",
        "positive": "Experimental apparatus for non-contact resistivity measurements of the\n  rock core plug based on magnetic induction: A new apparatus has been developed to measure the conductivity of rock\nsamples. The probe, which consists of multi-coil transmitters and receivers\ndoesn't require physical contact with the samples. The measurement is based on\nthe induction principle. The measurement system is validated by using saline\nsolutions and water-saturated sands of known conductivity. This work presents\ndetails of the development of a system of magnetic resistivity measurements by\nmagnetic induction for petrophysical applications. The first application\nconsists of measuring the resistivity of the core plug which is 0.038 m in\ndiameter. Currently the system is operating properly at a frequency of 50 kHz\nwith a current of up to 500 mA at 20 {\\deg}C. During the study two types of\nsamples were investigated: aqueous solutions with conductivities between 1 to\n100 mS/cm and rocks. Several tests were carried out with the objective of\ninvestigating the performance of the instrument, such as the experiment to\nobtain sensitivity for the measurement system as a function of the current\napplied to the transmitter coil."
    },
    {
        "anchor": "Temperature dependent Raman and x-ray studies of spin-ice pyrochlore\n  $Dy_2Ti_2O_7$ and non-magnetic pyrochlore $Lu_2Ti_2O_7$: We present here temperature-dependent Raman, x-ray diffraction and specific\nheat studies between room temperature and 12 K on single crystals of spin-ice\npyrochlore compound $Dy_2Ti_2O_7$ and its non-magnetic analogue $Lu_2Ti_2O_7$.\nRaman data show a \"new\" band not predicted by factor group analysis of\nRaman-active modes for the pyrochlore structure in $Dy_2Ti_2O_7$, appearing\nbelow a temperature of $T_c=$110 K with a concomitant contraction of the cubic\nunit cell volume as determined from the powder x-ray diffraction analysis. Low\ntemperature Raman experiments on O$^{18}$-isotope substituted $Dy_2Ti_2O_7$\nconfirm the phonon origin of the \"new\" mode. These findings, absent in\n$Lu_2Ti_2O_7$, suggest that the room temperature cubic lattice of the\npyrochlore $Dy_2Ti_2O_7$ undergoes a \"subtle\" structural transformation near\n$T_c$. We find anomalous \\textit{red-shift} of some of the phonon modes in both\nthe $Dy_2Ti_2O_7$ and the $Lu_2Ti_2O_7$ as the temperature decreases, which is\nattributed to strong phonon-phonon anharmonic interactions.",
        "positive": "Strain-induced heteronuclear charge disproportionation in EuMnO$_3$: Charge disproportionation transitions in complex oxides most commonly link\nhigh-temperature phases containing identical cations with the same oxidation\nstate and crystallographic site, to low-temperature phases in which charge\ntransfer between these ions results in unequal oxidation states. Here we\npropose, based on density functional calculations, a related concept that we\nterm \\textit{heteronuclear} charge disproportionation, in which charge transfer\noccurs between different elements on different crystallographic sites. We show\nfor the case of EuMnO$_3$ that such a transition from the experimentally\nobserved Eu$^{3+}$Mn$^{3+}$O$_3$ phase to the so far unknown\nEu$^{2+}$Mn$^{4+}$O$_3$ phase can be triggered by pressure and epitaxial\nstrain. We then identify measurable signatures to aid in an experimental\nexploration of the complex pressure- and biaxial strain-dependent phase\nstability of EuMnO$_3$ that we hope to motivate with our predictions. We\nsuggest other candidate crystal chemistries for heteronuclear charge\ndisproportionation, in which novel physics could emerge from the coexistence of\ninstabilities."
    },
    {
        "anchor": "Multiple-Fold Fermions and Topological Fermi Arcs Induced Catalytic\n  Enhancement in Nanoporous Electride C12A7: Topological materials are recently regarded as the idea catalysts due to the\nprotected surface metallic states and high carrier mobility, however the\nfundamental mechanism and the underlying relationship between the catalytic\nperformance and topological states are in debate. Here, by means of symmetry\nanalysis and first-principles calculations, we discover that the electride\nmaterial of C12A7 hosts the multiple-fold fermions due to the\ninterstitial-electrons, with the sixfold- and fourfold- degenerate points\nlocating at high symmetric points near the Fermi energy, which are identified\nas the underlying reason of the enhanced catalytic ability in C12A7-based\ncatalysts. The multiple-fold fermions exhibit much longer Fermi arcs on the\n(001) surface than traditional Weyl/Dirac fermions, the surface is thus highly\nchemical active and possesses a low Gibbs free energy for the hydrogen\nevolution reaction. The underlying relationship between catalytic performance\nand the topological surface state is explicitly verified by artificially hole\ndoping, external strain and similar electride without the Fermi arcs, where the\nGibbs free energies are significantly increased when the Fermi arcs is shifted\nto higher energy level. This work offers a guiding principle for understanding\ncatalytic nature of electrides and the topological quantum catalysts.",
        "positive": "High and low-temperature crystal and magnetic structures of\n  epsilon-Fe2O3 and their correlation to its magnetic properties: The crystal and magnetic structures of the orthorhombic e-Fe2O3 have been\nstudied by simultaneous Rietveld refinement of X-ray and neutron powder\ndiffraction data in combination with Mossbauer spectroscopy, as well as\nmagnetisation and heat capacity measurements. It has been found that above 150\nK the e-Fe2O3 polymorph is a collinear ferrimagnet with the magnetic moments\ndirected along the a axis, while the magnetic ordering below 80 K is\ncharacterised by a square-wave incommensurate structure. The transformation\nbetween these two states is a second order phase transition and involves subtle\nstructural changes mostly affecting the coordination of the tetrahedral and one\nof the octahedral Fe sites. The temperature dependence of the e-Fe2O3 magnetic\nproperties is discussed in the light of these results."
    },
    {
        "anchor": "Crystal structure and epitaxy of Bi2Te3 films grown on Si: We report comprehensive x-ray diffraction studies of the crystal structure\nand epitaxy of thin films of the topological insulator Bi2Te3 grown on Si (1 1\n1). The films are single crystals of high crystalline quality, which strongly\ndepends on that of their substrates, with in-plane epitaxial relationships of\nBi2Te3 [2 1 -3 0] || Si [1 -1 0] and Bi2Te3 [0 1 -1 0] || Si [1 1 -2] along\nwhich the lattices of 1x3 Bi2Te3 and 2x2 Si supercells are well matched. As the\nsamples age, we observe loss of crystalline Bi2Te3 film thickness accompanied\nwith roughening of the crystalline interfaces, formation of new crystalline\nphases as well as compositional and structural modification of the Si\nsubstrate, consistent with the diffusion of Te into the Si substrate.",
        "positive": "Stability and accuracy control of $\\mathbf{k \\cdot p}$ parameters: The $\\mathbf{k \\cdot p}$ method is a successful approach to obtain band\nstructure, optical and transport properties of semiconductors, and it depends\non external parameters that are obtained either from experiments, tight binding\nor ab initio calculations. Despite the widespread use of the $\\mathbf{k \\cdot\np}$ method, a systematic analysis of the stability and the accuracy of its\nparameters is not usual in the literature. In this work, we report a\ntheoretical framework to determine the $\\mathbf{k \\cdot p}$ parameters from\nstate-of-the-art hybrid density functional theory including spin-orbit\ncoupling, providing a calculation where the gap and spin-orbit energy splitting\nare in agreement with the experimental values. The accuracy of the set of\nparameters is enhanced by fitting over several directions at once, minimizing\nthe overall deviation from the original data. This strategy allows us to\nsystematically evaluate the stability, preserving the accuracy of the\nparameters, providing a tool to determine optimal parameters for specific\nranges around the ${\\Gamma}$-point. To prove our concept, we investigate the\nzinc blende GaAs that shows results in excellent agreement with the most\nreliable data in the literature."
    },
    {
        "anchor": "Photoluminescence from surface GaN/AlGaN quantum wells: Effect of the\n  surface states: We report on photoluminescence (PL) measurements at 85 K for GaN/AlGaN\nsurface quantum wells (SQW's) with a width in the range of 1.51-2.9 nm. The PL\nspectra show a redshift with decreasing SQW width, in contrast to the blueshift\nnormally observed for conventional GaN QW's of the same width. The effect is\nattributed to a strong coupling of SQW confined exciton states with surface\nacceptors. The PL hence originates from the recombination of\nsurface-acceptor-bound excitons. Two types of acceptors were identified.",
        "positive": "Unveiling the stacking-dependent electronic properties of 2D ultrathin\n  rare-earth metalloxenes family LnX$_2$ (Ln = Eu, Gd, Dy; X = Ge, Si): The studies of electronic effects in reduced dimensionality have become a\nfrontier in nanoscience due to exotic and highly tunable character of quantum\nphenomena. Recently, a new class of 2D ultrathin Ln$X_2$ metalloxenes composed\nof a triangular lattice of lanthanide ions (Ln) coupled with 2D-Xenes of\nsilicene or germanene ($X_2$) was introduced and studied with a particular\nfocus on magnetic and transport properties. However, the electronic properties\nof metalloxenes and their effective functionalization remain mainly unexplored.\nHere, using a number of experimental and theoretical techniques, we trace the\nevolution of electronic properties and magnetic ground state of metalloxenes\ntriggered by external perturbations. We demonstrate that the band structure of\nLn$X_2$ films can be uniquely modified by controlling the Xenes stacking,\nthickness, varying the rare-earth and host elements, and applying an external\nelectric field. Our findings suggest new pathways to manipulate the electronic\nproperties of 2D rare-earth magnets that can be adjusted for spintronics\napplications."
    },
    {
        "anchor": "Nuclear Quantum Effects Induce Metallization of Dense Solid Molecular\n  Hydrogen: We present an accurate computational study of the electronic structure and\nlattice dynamics of solid molecular hydrogen at high pressure. The band-gap\nenergies of the $C2/c$, $Pc$, and $P6_3/m$ structures at pressures of 250, 300,\nand 350 GPa are calculated using the diffusion quantum Monte Carlo (DMC)\nmethod. The atomic configurations are obtained from ab-initio path-integral\nmolecular dynamics (PIMD) simulations at 300 K and 300 GPa to investigate the\nimpact of zero-point energy and temperature-induced motion of the protons\nincluding anharmonic effects. We find that finite temperature and nuclear\nquantum effects reduce the band-gaps substantially, leading to metallization of\nthe $C2/c$ and $Pc$ phases via band overlap; the effect on the band-gap of the\n$P6_3/m$ structure is less pronounced. Our combined DMC-PIMD simulations\npredict that there are no excitonic or quasiparticle energy gaps for the $C2/c$\nand $Pc$ phases at 300 GPa and 300 K. Our results also indicate a strong\ncorrelation between the band-gap energy and vibron modes. This strong coupling\ninduces a band-gap reduction of more than 2.46 eV in high-pressure solid\nmolecular hydrogen. Comparing our DMC-PIMD with experimental results available,\nwe conclude that none of the structures proposed is a good candidate for phases\nIII and IV of solid hydrogen.",
        "positive": "Analysis of the structural characteristics and optoelectronic properties\n  of CaTiO3 as a non-toxic raw material for solar cells: a DFT study: Structural and optoelectronic properties of {\\alpha}, \\{beta}, {\\gamma}\nphases of calcium titanate are studied with the implementation of\nfirst-principles quantum-chemical calculations in the framework of DFT. When\noptimizing the geometry, the GGA approximation was used. The relaxed lattice\nparameters obtained by us are identical with the experimental analogs. It has\nbeen established that the most stable phase of calcium titanate is the\northorhombic syngony, which corresponds to the results of experimental\nmeasurements. It is shown that as the transition from the {\\alpha}-phase to the\n{\\gamma}-phase proceeds, the lattice constant parameters and the interatomic\ndistance in these systems increase. The optoelectronic properties of these\nmaterials have been studied using the Wien2k code. The high-precision TB-mBJ\napproximation was used to calculate the exchange-correlation effects. An\nanalysis of the electronic properties of these materials showed that all the\nstudied phases of calcium titanate belong to the class of wide-gap\nsemiconductors. The calculated band gaps for the cubic, tetragonal, and\northorhombic CaTiO3 systems are 2.83, 3.07, and 3.26 eV, respectively.\nAccording to the analysis of DOS-plots, it was found that the tetragonal phase\nof calcium titanate is characterized by the highest density of states.\nCalculations of the optical constants of the systems under study showed that\nthe CaTiO3 cubic system is characterized by an increased absorption capacity\nand a relatively high photoconductivity. However, for the other two phases of\ncalcium titanate, the calculations gave identical patterns, i.e., the\nabsorption and optical conductivity spectra of the tetragonal and orthorhombic\nCaTiO3 systems practically coincide."
    },
    {
        "anchor": "Surface-electronic structure of La(0001) and Lu(0001): Most spectroscopic methods for studying the electronic structure of metal\nsurfaces have the disadvantage that either only occupied or only unoccupied\nstates can be probed, and the signal is cut at the Fermi edge. This leads to\nsignificant uncertainties, when states are very close to the Fermi level. By\nperforming low-temperature scanning tunneling spectroscopy and ab initio\ncalculations, we study the surface-electronic structure of La(0001) and\nLu(0001), and demonstrate that in this way detailed information on the\nsurface-electronic structure very close to the Fermi energy can be derived with\nhigh accuracy.",
        "positive": "Kinetic Control of Morphology and Composition in Ge/GeSn Core/Shell\n  Nanowires: The growth of Sn-rich group-IV semiconductors at the nanoscale provides new\npaths for understanding the fundamental properties of metastable GeSn alloys.\nHere, we demonstrate the effect of the growth conditions on the morphology and\ncomposition of Ge/GeSn core/shell nanowires by correlating the experimental\nobservations with a theoretical interpretation based on a multi-scale approach.\nWe show that the cross-sectional morphology of Ge/GeSn core/shell nanowires\nchanges from hexagonal to dodecagonal upon increasing the supply of the Sn\nprecursor. This transformation strongly influences the Sn distribution as a\nhigher Sn content is measured under the {112} growth front. Ab-initio DFT\ncalculations provide an atomic-scale explanation by showing that Sn\nincorporation is favored at the {112} surfaces, where the Ge bonds are\ntensile-strained. A phase-field continuum model was developed to reproduce the\nmorphological transformation and the Sn distribution within the wire, shedding\nlight on the complex growth mechanism and unveiling the relation between\nsegregation and faceting. The tunability of the photoluminescence emission with\nthe change in composition and morphology of the GeSn shell highlights the\npotential of the core/shell nanowire system for opto-electronic devices\noperating at mid-infrared wavelengths."
    },
    {
        "anchor": "A new generation of effective core potentials: selected Lanthanides and\n  heavy elements: We construct correlation-consistent effective core potentials (ccECPs) for a\nselected set of heavy atoms and f-elements that are of significant current\ninterest in materials and chemical applications, including Y, Zr, Nb, Rh, Ta,\nRe, Pt, Gd, and Tb. As customary, ccECPs consist of spin-orbit averaged\nrelativistic effective potential (AREP) and effective spin-orbit (SO) terms.\nFor the AREP part, our constructions are carried out within a relativistic\ncoupled-cluster framework while also taking into objective function\none-particle characteristics for improved convergence in optimizations. The\ntransferability is adjusted using binding curves of hydride and oxide\nmolecules. We address the difficulties encountered with f-elements, such as the\npresence of large cores and multiple near-degeneracies of excited levels. For\nthese elements, we construct ccECPs with core-valence partitioning that\nincludes 4f-subshell in the valence space. The developed ccECPs achieve an\nexcellent balance between accuracy, size of the valence space, and\ntransferability and are also suitable to be used in plane wave codes with\nreasonable energy cutoffs.",
        "positive": "Data reduction procedure for correction of geometrical factors in the\n  analysis of specular x-ray reflectivity of small samples: For small samples, the modification of the XRR profile by the geometrical\nfactors manifesting due to profile and size of the beam and the size of the\nsample is significant. Geometrical factors extend till spill over angle which\nis often greater than critical angle for small samples. To separate the\ngeometrical factor, it is necessary to know the spill over angle. Since\ngeometrical factor is a smoothly varying function and extends beyond critical\nangle, it is impossible to determine the spill over angle from XRR profile of\nsmall samples. We have shown by comparing the normal XRR profile of a small\nsample with the XRR profile taken with a surface contact knife edge on the same\nsample, that the spill over angle can be determined. Thus we have developed a\nprocedure for data reduction for small samples and validated it with suitable\nexperiments. Unlike hitherto used methods which have drawbacks, this is a self\nconsistent method for data reduction"
    },
    {
        "anchor": "Spin-orbit torques acting upon a perpendicularly-magnetized Py layer: We show that Py, a commonly-used soft ferromagnetic material with weak\nanisotropy, can become perpendicularly-magnetized while depositing on Ta buffer\nlayer with Hf or Zr insertion layers (ILs) and MgO capping layer. By using two\ndifferent approaches, namely harmonic voltage measurement and hysteresis loop\nshift measurement, the dampinglike spin-orbit torque (DL-SOT) efficiencies from\nTa/IL/Py/IL/MgO magnetic heterostructures with perpendicular magnetic\nanisotropy are characterized. We find that though Ta has a significant spin\nHall effect, the DL-SOT efficiencies are small in systems with the Ta/Py\ninterface compared to that obtained from the control sample with the\ntraditional Ta/CoFeB interface. Our results indicate that the spin transparency\nfor the Ta/Py interface is much less than that for the Ta/CoFeB interface,\nwhich might be related to the variation of spin mixing conductance for\ndifferent interfaces.",
        "positive": "Structural and phase evolution in U$_3$Si$_2$ during steam corrosion: U$_3$Si$_2$ nuclear fuel is corroded in deuterated steam with in situ neutron\ndiffraction. Density functional theory is coupled with rigorous thermodynamic\ndescription of the hydride including gas/solid entropy contributions. H absorbs\nin the 2$b$ interstitial site of U$_3$Si$_2$H$_x$ and moves to 8$j$ for $x\\ge\n0.5$. Hydriding forces lattice expansion and change in $a/c$ ratio linked to\nsite preference. Rietveld refinement tracks the corrosion reactions at 350-500\n\\deg C and preference for the 8j site. Above 375 \\deg C, formation of UO$_2$,\nU$_3$Si$_5$ and USi$_3$ take place in the grain boundaries and bulk. Hydriding\noccurs in bulk and precedes other reactions."
    },
    {
        "anchor": "Noncentrosymmetric compensated half-metal hosting pure spin Weyl nodes,\n  triple nodal points, nodal loops, and nexus fermions: Materials containing multiple topological characteristics become more exotic\nwhen combined with noncentrosymmetric crystal structures and unusual magnetic\nphases such as the compensated half-metal state, which is gapped in one spin\ndirection and conducting in the other. First principles calculations reveal\nthese multiple topological features in the compensated half-metal Cr$_2$CoAl\nhaving neither time-reversal nor inversion symmetries. In the absence of\n(minor) spin-orbit coupling (SOC), there are (1) a total of twelve pairs of\nmagnetic Weyl points, (2) three distinct sets of triple nodal points near the\nFermi level that are (3) interconnected with six symmetry related nodal lines.\nThis combination gives rise to fully spin polarized nexus fermions, in a system\nwith broken time-reversal symmetry but negligible macroscopic magnetic field.\nThe observed high Curie temperature of 750 K and calculated SOC hybridization\nmixing of several meV should make these nexus fermions readily measurable.\nUnlike topological features discussed for other Heuslers which emphasize their\nstrong ferromagnetism, this compensated half-metal is impervious to typical\nmagnetic fields, thus providing a complementary set of experimental phenomena.\nMaking use of the soft calculated magnetic state, large magnetic fields can be\nused to rotate the direction of magnetism, during which certain topological\nfeatures will evolve. Our results suggest that these features may be common in\ninverse-Heusler systems, particularly the isostructural and isovalent Ga and In\nanalogs.",
        "positive": "Oxygen-related traps in pentacene thin films: Energetic position and\n  implications for transistor performance: We studied the influence of oxygen on the electronic trap states in a\npentacene thin film. This was done by carrying out gated four-terminal\nmeasurements on thin-film transistors as a function of temperature and without\never exposing the samples to ambient air. Photooxidation of pentacene is shown\nto lead to a peak of trap states centered at 0.28 eV from the mobility edge,\nwith trap densities of the order of 10(18) cm(-3). These trap states need to be\noccupied at first and cause a reduction in the number of free carriers, i.e. a\nconsistent shift of the density of free holes as a function of gate voltage.\nMoreover, the exposure to oxygen reduces the mobility of the charge carriers\nabove the mobility edge. We correlate the change of these transport parameters\nwith the change of the essential device parameters, i.e. subthreshold\nperformance and effective field-effect mobility. This study supports the\nassumption of a mobility edge for charge transport, and contributes to a\ndetailed understanding of an important degradation mechanism of organic\nfield-effect transistors. Deep traps in an organic field-effect transistor\nreduce the effective field-effect mobility by reducing the number of free\ncarriers and their mobility above the mobility edge."
    },
    {
        "anchor": "Vertical Ferroelectricity in Van der Waals Materials: Models and Devices: Ferroelectricity has a wide range of applications in functional electronics\nand is extremely important for the development of next-generation information\nstorage technology, but it is difficult to achieve due to its special symmetry\nrequirements. In this letter, based on van derWaals stacking, a generic model\nis proposed for realizing ferroelectric devices, where a freely movable center\nlayer is packaged in two fixed and symmetrically stacked layers. In this model,\nthe ferroelectric phase transition can be realized between the two equivalent\nand eccentric ground stacking-states with opposite polarizations. By means of\nfirst-principles calculations, taking the h-BN/h-BN/h-BN and h-BN/Graphene/h-BN\nas feasible models, we carefully evaluate the magnitude of ferroelectricity.\nThe corresponding polarizations are estimated as 1.83 and 1.35 pC/m,\nrespectively, which are comparable to the sliding ferroelectricity. Such a new\ntri-layer model of vertical ferroelectricity can be constructed by arbitrary\nvan derWaals semiconducting materials, and usually holds low switching barrier.\nOptimized material combinations with remarkable polarization are highly\nexpectable to be discovered from the huge candidate set for future information\nstorage.",
        "positive": "A comparative DFT study of electronic properties of 2H-, 4H- and\n  6H-SiC(0001) and SiC(000-1) clean surfaces: Significance of the surface Stark\n  effect: Electric field, uniform within the slab, emerging due to Fermi level pinning\nat its both sides is analyzed using DFT simulations of the SiC surface slabs of\ndifferent thickness. It is shown that for thicker slab the field is nonuniform\nand this fact is related to the surface state charge. Using the electron\ndensity and potential profiles it is proved that for high precision simulations\nit is necessary to take into account enough number of the Si-C layers. We show\nthat using 12 diatomic layers leads to satisfactory results. It is also\ndemonstrated that the change of the opposite side slab termination, both by\ndifferent type of atoms or by their location, can be used to adjust electric\nfield within the slab, creating a tool for simulation of surface properties,\ndepending on the doping in the bulk of semiconductor. Using these simulations\nit was found that, depending on the electric field, the energy of the surface\nstates changes in a different way than energy of the bulk states. This\ncriterion can be used to distinguish Shockley and Tamm surface states. The\nelectronic properties, i.e. energy and type of surface states of the three\nclean surfaces: 2H-, 4H-, 6H-SiC(0001), and SiC($000 \\bar{1}$) are analyzed and\ncompared using field dependent DFT simulations."
    },
    {
        "anchor": "How the Chemical Composition Alone Can Predict Vibrational Free Energies\n  and Entropies of Solids: Computing vibrational free energies ($F_{vib}$) and entropies ($S_{vib}$) has\nposed a long standing challenge to the high-throughput ab initio investigation\nof finite temperature properties of solids. Here we use machine-learning\ntechniques to efficiently predict $F_{vib}$ and $S_{vib}$ of crystalline\ncompounds in the Inorganic Crystal Structure Database. By employing descriptors\nbased simply on the chemical formula and using a training set of only 300\ncompounds, mean absolute errors of less than 0.04 meV/K/atom (15 meV/atom) are\nachieved for $S_{vib}$ ($F_{vib}$), whose values are distributed within a range\nof 0.9 meV/K/atom (300 meV/atom.) In addition, for training sets containing\nfewer than 2,000 compounds the chemical formula alone is shown to perform as\nwell as, if not better than, four other more complex descriptors previously\nused in the literature. The accuracy and simplicity of the approach mean that\nit can be advantageously used for the fast screening of phase diagrams or\nchemical reactions at finite temperatures.",
        "positive": "First-principles Hubbard U and Hund's J corrected approximate\n  density-functional theory predicts an accurate fundamental gap in rutile and\n  anatase TiO2: Titanium dioxide (TiO$_2$) presents a long-standing challenge for approximate\nKohn-Sham density-functional theory (KS-DFT), as well as to its\nHubbard-corrected extension, DFT+$U$. We find that a previously proposed\nextension of first-principles DFT+$U$ to incorporate a Hund's $J$ correction,\ntermed DFT+$U$+$J$, in combination with parameters calculated using a recently\nproposed linear-response theory, predicts fundamental band-gaps accurate to\nwell within the experimental uncertainty in rutile and anatase TiO$_2$. Our\napproach builds upon established findings that Hubbard correction to both\ntitanium $3d$ and oxygen $2p$ subspaces in TiO$_2$, symbolically giving\nDFT+$U^{d,p}$, is necessary to achieve acceptable band-gaps using DFT+$U$. This\nrequirement remains when the first-principles Hund's $J$ is included. We also\nfind that the calculated gap depends on the correlated subspace definition even\nwhen using subspace-specific first-principles $U$ and $J$ parameters. Using the\nsimplest reasonable correlated subspace definition and underlying functional,\nthe local density approximation, we show that high accuracy results from using\na relatively uncomplicated form of the DFT+$U$+$J$ functional. For closed-shell\nsystems such as TiO$_2$, we describe how various DFT+$U$+$J$ functionals reduce\nto DFT+$U$ with suitably modified parameters, so that reliable band gaps can be\ncalculated for rutile and anatase with no modifications to a conventional\nDFT+$U$ code."
    },
    {
        "anchor": "Tunnel Junction Enhanced Nanowire Ultraviolet Light Emitting Diodes: Polarization engineered interband tunnel junctions (TJs) are integrated in\nnanowire ultraviolet (UV) light emitting diodes (LEDs). A ~6V reduction in\nturn-on voltage is achieved by the integration of tunnel junction at the base\nof polarization doped nanowire UV LEDs. Moreover, efficient hole injection into\nthe nanowire LEDs leads to suppressed efficiency droop in TJ integrated\nnanowire LEDs. The combination of both reduced bias voltage and increased hole\ninjection increases the wall plug efficiency in these devices. More than 100\nmicrowatts of UV emission at ~310 nm is measured with external quantum\nefficiency in the range of 4 - 6 m%. The realization of tunnel junction within\nthe nanowire LEDs opens a pathway towards the monolithic integration of\ncascaded multi-junction nanowire LEDs on silicon.",
        "positive": "Mode Localization and Suppressed Heat Transport in Amorphous Alloys: Glasses usually represent the lower limit for the thermal conductivity of\nsolids, but a fundamental understanding of lattice heat transport in amorphous\nmaterials can provide design rules to beat such a limit. Here we investigate\nthe role of mass disorder in glasses by studying amorphous silicon-germanium\nalloy (a-Si$_{1-x}$Ge$_x$) over the full range of atomic concentration from\n$x=0$ to $x=1$, using molecular dynamics and the quasi-harmonic Green-Kubo\nlattice dynamics formalism. We find that the thermal conductivity of\na-Si$_{1-x}$Ge$_x$ as a function of $x$ exhibits a smoother U-shape than in\ncrystalline mass-disordered alloys. The main contribution to the initial drop\nof thermal conductivity at low Ge concentration stems from the localization of\notherwise extended modes that make up the lowest 8\\% of the population by\nfrequency. Contributions from intermediate frequency modes are decreased more\ngradually with increasing Ge to reach a broad minimum thermal conductivity\nbetween concentrations of Ge from $x=0.25$ to $0.75$."
    },
    {
        "anchor": "Interplay between adsorbates and polarons: CO on rutile TiO$_2$(110): Polaron formation plays a major role in determining the structural,\nelectrical and chemical properties of ionic crystals. Using a combination of\nfirst principles calculations and scanning tunneling microscpoy/atomic force\nmicroscopy (STM/AFM), we analyze the interaction of polarons with CO molecules\nadsorbed on the rutile TiO$_2$(110) surface. Adsorbed CO shows attractive\ncoupling with polarons in the surface layer, and repulsive interaction with\npolarons in the subsurface layer. As a result, CO adsorption depends on the\nreduction state of the sample. For slightly reduced surfaces, many adsorption\nconfigurations with comparable adsorption energies exist and polarons reside in\nthe subsurface layer. At strongly reduced surfaces, two adsorption\nconfigurations dominante: either inside an oxygen vacancy, or at surface\nTi$_{5c}$ sites, coupled with a surface polaron.",
        "positive": "Energetic molding of chiral magnetic bubbles: Topologically protected magnetic structures such as skyrmions and domain\nwalls (DWs) have drawn a great deal of attention recently due to their thermal\nstability and potential for manipulation by spin current, which is the result\nof chiral magnetic configurations induced by the interfacial\nDzyaloshinskii-Moriya Interaction (DMI). Designing devices that incorporate DMI\nnecessitates a thorough understanding of how the interaction presents and can\nbe measured. One approach is to measure growth asymmetry of chiral bubble\ndomains in perpendicularly magnetized thin films, which has been described\nelsewhere by thermally activated DW motion. Here, we demonstrate that the\nanisotropic angular dependence of DW energy originating from the DMI is\ncritical to understanding this behavior. Domains in Co/Ni multi-layers are\nobserved to preferentially grow into non-elliptical teardrop shapes, which vary\nwith the magnitude of an applied in-plane field. We model the domain profile\nusing energetic calculations of equilibrium shape via the Wulff construction,\nwhich explains both the teardrop shape and the reversal of growth symmetry at\nlarge fields."
    },
    {
        "anchor": "Ultrafast spherulitic crystal growth as a stress-induced phenomenon\n  specific of fragile glass-formers: We propose a model for the abrupt emergence, below temperatures close to the\nglass transition, of the ultra-fast (GC) steady mode of spherulitic crystal\ngrowth in deeply undercooled liquids. We interpret this phenomenon as\ncontrolled by the interplay between the generation of stresses by\ncrystallization and their partial release by flow in the surrounding amorphous\nvisco-elastic matrix. Our model is consistent with both the observed ratios\n($\\sim10^4$) of fast-to-slow velocities and the fact that fast growth emerges\nclose to the glass transition. It leads us to conclude that the existence of a\nfast growth regime requires both (i) a high fragility of the glassformer; (ii)\nthe fine sub-structure specific of spherulites. It finally predicts that the\ntransition is hysteretic, thus allowing for an independent experimental test.",
        "positive": "Anomalous high-pressure Jahn-Teller behavior in CuWO4: High-pressure optical-absorption measurements performed in CuWO4 up to 20 GPa\nprovide experimental evidence of the persistence of the Jahn-Teller (JT)\ndistortion in the whole pressure range both in the low-pressure triclinic and\nin the highpressure monoclinic phase. The electron-lattice coupling associated\nwith the eg(Exe) and t2g(Txe) orbitals of Cu2+ in CuWO4 are obtained from\ncorrelations between the JT distortion of the CuO6 octahedron and the\nassociated structure of Cu2+ d-electronic levels. This distortion and its\nassociated JT energy (EJT) decrease upon compression in both phases. However,\nboth the distortion and associated EJT increase sharply at the phase transition\npressure (PT = 9.9 GPa) and we estimate that the JT distortion persists for a\nwide pressure range not being suppressed up to 37 GPa. These results shed light\non the transition mechanism of multiferroic CuWO4 suggesting that the\npressureinduced structural phase transition is a way to minimize the distortive\neffects associated with the toughness of the JT distortion."
    },
    {
        "anchor": "Computational studies on magnetism and ferroelectricity: Magnetics, ferroelectrics and multiferroics have attracted great attentions\nbecause they are not only extremely important for investigating fundamental\nphysics, but also have important applications in information technology. Here,\nrecent computational studies on magnetism and ferroelectricity are reviewed. We\nfirst give a brief introduction to magnets, ferroelectrics, and multiferroics.\nThen, theoretical models and corresponding computational methods for\ninvestigating these materials are presented. In particular, a new method for\ncomputing the linear magnetoelectric coupling tensor without applying an\nexternal field in the first principle calculations is proposed for the first\ntime. The functionalities of our homemade Property Analysis and Simulation\nPackage for materials (PASP) and its applications in the field of magnetism and\nferroelectricity are discussed. Finally, we summarize this review and give a\nperspective on possible directions of future computational studies on magnetism\nand ferroelectricity.",
        "positive": "Thermoelectric generation based on spin Seebeck effects: The spin Seebeck effect (SSE) refers to the generation of a spin current as a\nresult of a temperature gradient in magnetic materials including insulators.\nThe SSE is applicable to thermoelectric generation because the thermally\ngenerated spin current can be converted into a charge current via spin-orbit\ninteraction in conductive materials adjacent to the magnets. The\ninsulator-based SSE device exhibits unconventional characteristics potentially\nuseful for thermoelectric applications, such as simple structure, device-design\nflexibility, and convenient scaling capability. In this article, we review\nrecent studies on the SSE from the viewpoint of thermoelectric applications.\nFirstly, we introduce the thermoelectric generation process and measurement\nconfiguration of the SSE, followed by showing fundamental characteristics of\nthe SSE device. Secondly, a theory of the thermoelectric conversion efficiency\nof the SSE device is presented, which clarifies the difference between the SSE\nand conventional thermoelectric effects and the efficiency limit of the SSE\ndevice. Finally, we show preliminary demonstrations of the SSE in various\ndevice structures for future thermoelectric applications and discuss prospects\nof the SSE-based thermoelectric technologies."
    },
    {
        "anchor": "Electron-phonon physics from first principles using the EPW code: EPW is an open-source software for $\\textit{ab initio}$ calculations of\nelectron-phonon interactions and related materials properties. The code\ncombines density functional perturbation theory and maximally-localized Wannier\nfunctions to efficiently compute electron-phonon coupling matrix elements on\nultra-fine Brillouin zone grids. This data is employed for predictive\ncalculations of temperature-dependent properties and phonon-assisted quantum\nprocesses in bulk solids and low-dimensional materials. Here, we report on\nsignificant new developments in the code that occurred during the period\n2016-2022, namely: a transport module for the calculation of charge carrier\nmobility and conductivity under electric and magnetic fields within the\n$\\textit{ab initio}$ Boltzmann transport equation; a superconductivity module\nfor the calculation of critical temperature and gap structure in\nphonon-mediated superconductors within the $\\textit{ab initio}$ anisotropic\nmulti-band Eliashberg theory; an optics module for calculations of\nphonon-assisted indirect transitions; a module for the calculation of small and\nlarge polarons without supercells using the $\\textit{ab initio}$ polaron\nequations; and a module for calculating electron-phonon couplings, band\nstructure renormalization, and temperature-dependent optical spectra using the\nspecial displacement method. For each capability, we outline the methodology\nand implementation, and provide example calculations. We describe recent code\nrefactoring to prepare EPW for exascale architectures, we discuss efficient\nparallelization strategies, and report on extreme parallel scaling tests.",
        "positive": "Factors Responsible for the Stability and the Existence of a Clean\n  Energy Gap of a Silicon Nanocluster: We present a critical theoretical study of electronic properties of silicon\nnanoclusters, in particular the roles played by symmetry, relaxation, and\nhydrogen passivation on the the stability, the gap states and the energy gap of\nthe system using the order-N [O(N)] non-orthogonal tight-binding molecular\ndynamics and the local analysis of electronic structure."
    },
    {
        "anchor": "Thermal Oxidation of WSe2 Nano-sheets Adhered on SiO2/Si Substrates: Due to the drastically different intralayer versus interlayer bonding\nstrengths, the mechanical, thermal, and electrical properties of\ntwo-dimensional (2D) materials are highly anisotropic between the in-plane and\nout-of-plane directions. The structural anisotropy may also play a role in\nchemical reactions, such as oxidation, reduction, and etching. Here, the\ncomposition, structure, and electrical properties of mechanically exfoliated\nWSe2 nano- sheets on SiO2/Si substrates were studied as a function of the\nextent of thermal oxidation. A major component of the oxidation, as indicated\nfrom optical and Raman data, starts from the nano-sheet edges and propagates\nlaterally towards the center. Partial oxidation also occurs in certain areas at\nthe surface of the flakes, which are shown to be highly conductive by microwave\nimpedance microscopy. Using secondary ion mass spectroscopy, we also observed\nextensive oxidation at the WSe2/SiO2 interface. The combination of multiple\nmicrocopy methods can thus provide vital information on the spatial evolution\nof chemical reactions on 2D materials and the nanoscale electrical properties\nof the reaction products.",
        "positive": "Exciton Binding Energy in small organic conjugated molecule: For small organic conjugated molecules the exciton binding energy can be\ncalculated treating molecules as conductor, and is given by a simple relation\nBE \\approx e2/(4{\\pi}{\\epsilon}0{\\epsilon}R), where {\\epsilon} is the\ndielectric constant and R is the equivalent radius of the molecule. However, if\nthe molecule deviates from spherical shape, a minor correction factor should be\nadded."
    },
    {
        "anchor": "Topological phase transition between distinctWeyl semimetal states in\n  MoTe2: We present experimental evidence of an intriguing phase transition between\ndistinct topological states in the type-II Weyl semimetal MoTe2. We observe\nanomalies in the Raman phonon frequencies and linewidths as well as electronic\nquasielastic peaks around 70 K, which, together with structural, thermodynamic\nmeasurements, and electron-phonon coupling calculations, demonstrate a\ntemperature-induced transition between two topological phases previously\nidentified by contrasting spectroscopic measurements. An analysis of\nexperimental data suggests electron-phonon coupling as the main driving\nmechanism for the change of key topological characters in the electronic\nstructure of MoTe2.We also find the phase transition to be sensitive to sample\nconditions distinguished by synthesis methods. These discoveries of temperature\nand material condition-dependent topological phase evolutions and transitions\nin MoTe2 advance the fundamental understanding of the underlying physics and\nenable an effective approach to tuning Weyl semimetal states for technological\napplications.",
        "positive": "Influence of the vicinal substrate miscut on the anisotropic\n  two-dimensional electronic transport in Al2O3-SrTiO3 heterostructures: The electrical resistance of the two-dimensional electron system (2DES) which\nforms at the interface of SrTiO3 (STO)-based heterostructures displays\nanisotropic transport with respect to the direction of current flow at low\ntemperature. We have investigated the influence of terraces at the surface of\nSTO substrates from which the 2DES are prepared. Such terraces are always\npresent in commercially available STO substrates due to the tolerance of\nsurface preparation which result in small miscut angles of the order of gamma ~\n0.1{\\deg} with respect to the surface normal. By a controlled increase of the\nsubstrate miscut we could systematically reduce the width of the terraces and\nthereby increase the density of substrate surface steps. The in-plane\nanisotropy of the electrical resistance was studied as a function of the miscut\nangle gamma and found to be mainly related to interfacial scattering arising\nfrom the substrate surface steps. However, the influence of gamma was notably\nreduced by the occurrence of step-bunching and lattice-dislocations in the STO\nsubstrate material.\n  Magnetoresistance (MR) depends on the current orientation as well, reflecting\nthe anisotropy of carrier mobility. For gamma >= 2{\\deg}, MR is substantially\nenhanced and shows the trend towards a linear field dependence which is typical\nfor inhomogeneous conductors. From weak-antilocalization observed at small\nmagnetic field we deduce information on inelastic scattering and spin-orbit\ncoupling. While the field scale associated with a Rashba-type spin-orbit\ncoupling in 2D weak-localization does not show a pronounced correlation with\ngamma, distinct changes of the scale are associated with inelastic scattering."
    },
    {
        "anchor": "Unidirectionality of spin waves in Synthetic Antiferromagnets: We study the frequency non-reciprocity of the spin waves in symmetric\nCoFeB/Ru/CoFeB synthetic antiferromagnets stacks set in the scissors state by\nin-plane applied fields. Using a combination of Brillouin Light Scattering and\npropagating spin wave spectroscopy experiments, we show that the acoustical\nspin waves in synthetic antiferromagnets possess a unique feature if their\nwavevector is parallel to the applied field: the frequency non-reciprocity due\nto layer-to-layer dipolar interactions can be so large that the acoustical spin\nwaves transfer energy in a unidirectional manner for a wide and bipolar\ninterval of wavevectors. Analytical modeling and full micromagnetic\ncalculations are conducted to account for the dispersion relations of the\noptical and acoustical spin waves for arbitrary field orientations. Our\nformalism provides a simple and direct method to understand and design devices\nharnessing unidirectional propagation of spin waves in synthetic\nantiferromagnets.",
        "positive": "Revealing Ultrafast Phonon Mediated Inter-Valley Scattering through\n  Transient Absorption and High Harmonic Spectroscopies: Processes involving ultrafast laser driven electron-phonon dynamics play a\nfundamental role in the response of quantum systems in a growing number of\nsituations of interest, as evidenced by phenomena such as strongly driven phase\ntransitions and light driven engineering of material properties. To show how\nthese processes can be captured from a computational perspective, we simulate\nthe transient absorption spectra and high harmonic generation signals\nassociated with valley selective excitation and intra-band charge carrier\nrelaxation in monolayer hexagonal boron nitride. We show that the\nmulti-trajectory Ehrenfest dynamics approach, implemented in combination with\nreal-time time-dependent density functional theory and tight-binding models,\noffers a simple, accurate and efficient method to study ultrafast\nelectron-phonon coupled phenomena in solids under diverse pump-probe regimes\nwhich can be easily incorporated into the majority of real-time ab-initio\nsoftware packages."
    },
    {
        "anchor": "Graphene on Si(111)7x7: We demonstrate that it is possible to mechanically exfoliate graphene under\nultra high vacuum conditions on the atomically well defined surface of single\ncrystalline silicon. The flakes are several hundred nanometers in lateral size\nand their optical contrast is very faint in agreement with calculated data.\nSingle layer graphene is investigated by Raman mapping. The G and 2D peaks are\nshifted and narrowed compared to undoped graphene. With spatially resolved\nKelvin probe measurements we show that this is due to p-type doping with hole\ndensities of n_h \\simeq 6x10^{12} cm^{-2}. The in vacuo preparation technique\npresented here should open up new possibilities to influence the properties of\ngraphene by introducing adsorbates in a controlled way.",
        "positive": "The structural and electronic properties of Stone-Wales defective\n  zigzag/armchair antimonene nanotubes: First-principles calculations: Geometric optimization and electronic properties of Stone-Wales defective\nantimonene nanotubes are calculated by the method of first -principle\ncalculations based on density functional theory. Various nanotubes are\ninvestigated according to the possible orientations of zigzag/armchair\nnanostructures when Stone-Wales defects are formed. The band structures,\npartial density of states and atomic orbitals are calculated to reveal the\nmechanism of influence of Stone-Wales defects on antimonene nanotubes. When the\nstructure of antimonene changes from monolayer to tube, the indirect gap\nsemiconductor antimonene transforms to a direct gap one. Moreover, the\ncharacter of direct band gap for the antimonene nanotube is preserved with the\nStone-Wales defect forming, while the energy of conduction band bottoms change\ndue to the intervene of the defect energy level in the band gaps. These results\nmay provide valuable references to the development and design of novel\nnanotubes based on antimonene nanotubes."
    },
    {
        "anchor": "Temperature-dependent resistivity of ferromagnetic GaMnAs: Interplay\n  between impurity scattering and many-body effects: The static conductivity of the dilute magnetic semiconductor GaMnAs is\ncalculated using the memory function formalism and time-dependent\ndensity-functional theory to account for impurity scattering and to treat\nHartree and exchange interactions within the hole gas. We find that the Coulomb\nscattering off the charged impurities alone is not sufficient to explain the\nexperimentally observed drop in resistivity below the ferromagnetic transition\ntemperature: the often overlooked scattering off the fluctuations of localized\nspins is shown to play a significant role.",
        "positive": "Surface Effect on Domain Wall Width in Ferroelectrics: We study the effect of depolarization field related with inhomogeneous\npolarization distribution, strain and surface energy parameters on a domain\nwall profile near the surface of a ferroelectric film within the framework of\nLandau-Ginzburg-Devonshire phenomenology. Both inhomogeneous elastic stress and\npositive surface energy lead to the wall broadening at electrically screened\nsurface. For ferroelectrics with weak piezoelectric coupling, the extrapolation\nlength that defines surface energy parameter, affects the wall broadening more\nstrongly than inhomogeneous elastic stress. Unexpectedly, the domain wall\nprofile follows a long-range power law when approaching the surface, while it\nsaturates exponentially in the bulk. In materials with high piezoelectric\ncoupling and negligibly small surface energy (i.e. high extrapolation length)\ninhomogeneous elastic stress effect dominates."
    },
    {
        "anchor": "Invertible and Non-invertible Alloy Ising Models: Physical properties of alloys are compared as computed from ``direct'' and\n``inverse'' procedures. The direct procedure involves Monte Carlo simulations\nof a set of local density approximation (LDA)-derived pair and multibody\ninteractions {\\nu_f}, generating short-range order (SRO), ground states, order-\ndisorder transition temperatures, and structural energy differences. The\ninverse procedure involves ``inverting'' the SRO generated from {\\nu_f} via\ninverse-Monte-Carlo to obtain a set of pair only interactions {\\tilde{\\nu}_f}.\nThe physical properties generated from {\\tilde{\\nu}_f} are then compared with\nthose from {\\nu_f}. We find that (i) inversion of the SRO is possible (even\nwhen {\\nu_f} contains multibody interactions but {\\tilde{\\nu}_f} does not) but,\n(ii) the resulting interactions {\\tilde{\\nu}_f} agree with the input\ninteractions {\\nu_f} only when the problem is dominated by pair interactions.\nOtherwise, {\\tilde{\\nu}_f} are very different from {\\nu_f}. (iii) The same SRO\npattern can be produced by drastically different sets {\\nu_f}. Thus, the\neffective interactions deduced from inverting SRO are not unique. (iv)\nInverting SRO always misses configuration-independent (but composition-\ndependent) energies such as the volume deformation energy G(x); consequently,\nthe ensuing {\\tilde{\\nu}_f} cannot be used to describe formation enthalpies or\ntwo-phase regions of the phase diagram, which depend on G(x).",
        "positive": "Manifestion of structural Higgs and Goldstone modes in the hexagonal\n  manganites: Structural phase transitions described by Mexican hat potentials should in\nprinciple exhibit aspects of Higgs and Goldstone physics. Here, we investigate\nthe relationship between the phonons that soften at such structural phase\ntransitions and the Higgs- and Goldstone-boson analogues associated with the\ncrystallographic Mexican hat potential. We show that, with the exception of\nsystems containing only one atom type, the usual Higgs and Goldstone modes are\nrepresented by a combination of several phonon modes, with the lowest energy\nphonons of the relevant symmetry having substantial contribution. Taking the\nhexagonal manganites as a model system, we identify these modes using Landau\ntheory, and predict the temperature dependence of their frequencies using\nparameters obtained from density functional theory. Separately, we calculate\nthe additional temperature dependence of all phonon mode frequencies arising\nfrom thermal expansion within the quasi-harmonic approximation. We predict that\nHiggs-mode softening will dominate the low-frequency vibrational spectrum of\nInMnO$_3$ between zero kelvin and room-temperature, whereas the behavior of\nErMnO$_3$ will be dominated by lattice expansion effects. We present\ntemperature-dependent Raman scattering data that support our predictions, in\nparticular confirming the existence of the Higgs mode in InMnO$_3$."
    },
    {
        "anchor": "Phase transition between (2 x 1) and c(8 x 8) reconstructions observed\n  on the Si(001) surface around 600C: The Si(001) surface subjected to different treatments in ultrahigh vacuum\nmolecular beam epitaxy chamber for SiO$_2$ film decomposition has been in situ\ninvestigated by reflected high energy electron diffraction (RHEED) and high\nresolution scanning tunnelling microscopy (STM). A transition between (2 x 1)\nand (4 x 4) RHEED patterns was observed. The (4 x 4) pattern arose at T <~600C\nduring sample posttreatment cooling. The reconstruction was observed to be\nreversible. The c(8 x 8) structure was revealed by STM at room temperature on\nthe same samples. The (4 x 4) patterns have been evidenced to be a\nmanifestation of the c(8 x 8) surface structure in RHEED. The phase transition\nappearance has been found to depend on thermal treatment conditions and sample\ncooling rate.",
        "positive": "Two-temperature pair potentials and phonon spectra for simple metals in\n  the warm dense matter regime: We develop ion-ion pair potentials for Al, Na and K for densities and\ntemperatures relevant to the warm-dense-matter (WDM) regime. Furthermore, we\nemphasize non-equilibrium states where the ion temperature $T_i$ differs from\nthe electron temperature $T_e$. This work focuses mainly on ultra-fast\nlaser-metal interactions where the energy of the laser is almost exclusively\ntransferred to the electron sub-system over femtosecond time scales. This\nresults in a two-temperature system with $T_e>T_i$ and with the ions still at\nthe initial room temperature $T_i=T_r$. First-principles calculations, such as\ndensity functional theory (DFT) or quantum Monte Carlo, are as yet not fully\nfeasible for WDM conditions due to lack of finite-$T$ features, e.g.\npseudopotentials, and extensive CPU time requirements. Simpler methods are\nneeded to study these highly complex systems. We propose to use two-temperature\npair potentials $U_{ii}(r, T_i,T_e)$ constructed from linear-response theory\nusing the non-linear electron density $n(\\mathbf{r})$ obtained from finite-$T$\nDFT with a single ion immersed in the appropriate electron fluid. We compute\nequilibrium phonon spectra at $T_r$ which are found to be in very good\nagreement with experiments. This gives credibility to our non-equilibrium\nphonon dispersion relations which are important in determining thermophysical\nproperties, stability, energy-relaxation mechanisms and transport coefficients."
    },
    {
        "anchor": "The role of C2 in nanocrystalline diamond growth: This paper presents findings from a study of nanocrystalline diamond (NCD)\ngrowth in a microwave plasma chemical vapour deposition (CVD) reactor. NCD\nfilms were grown using Ar/H2/CH4 and He/H2/CH4 gas compositions. The resulting\nfilms were characterised using Raman spectroscopy, scanning electron microscopy\nand atomic force microscopy. Analysis revealed an estimated grain size of the\norder of 50 nm, growth rates in the range 0.01 to 0.3 um/h and sp3 and sp2\nbonded carbon content consistent with that expected for NCD. The C2 Swan band\nwas probed using cavity ring-down spectroscopy (CRDS) to measure the absolute\nC2 (a) number density in the plasma during diamond film growth. The number\ndensity in the Ar/H2/CH4 plasmas was in the range 2 to 4 x 10^12 cm-3, but\nfound to be present in quantities too low to measure in the He/H2/CH4 plasmas.\nOptical emission spectrometry (OES) was employed to determine the relative\ndensities of the C2 excited state (d) in the plasma. The fact that similar NCD\nmaterial was grown whether using Ar or He as the carrier gas suggests that C2\ndoes not play a major role in the growth of nanocrystalline diamond.",
        "positive": "Effect of Sb deficiency on the thermoelectric properties of Zn4Sb3: We have investigated the effect of Sb-deficiency on the thermoelectric figure\nof merit (zT) of Zn4Sb3 prepared by solid state reaction route. At high\ntemperatures, the Seebeck coefficient (S) and electrical conductivity\n({\\sigma}) increase with increase in Sb deficiency whereas the thermal\nconductivity (\\k{appa}) decreases giving rise to an increase in the overall zT\nvalue. The observations suggest that creation of vacancies could be an\neffective route in improving the thermoelectric properties of Zn4Sb3 system.\nThis coupled to nanostructuring strategy could lead to the ultimate maximum\nvalue of zT in this system for high temperature thermoelectric applications."
    },
    {
        "anchor": "Coexistence of ferromagnetism and spin-orbit coupling by incorporation\n  of platinum in two-dimensional VSe$_2$: We report on a novel material, namely two-dimensional (2D)\nV$_{1-x}$Pt$_x$Se$_2$ alloy, exhibiting simultaneously ferromagnetic order and\nRashba spin-orbit coupling. While ferromagnetism is absent in 1T-VSe$_2$ due to\nthe competition with the charge density wave phase, we demonstrate\ntheoretically and experimentally that the substitution of vanadium by platinum\nin VSe$_2$ (10-50 %) to form an homogeneous 2D alloy restores ferromagnetic\norder with Curie temperatures of 6 K for 5 monolayers and 25 K for one\nmonolayer of V$_{0.65}$Pt$_{0.35}$Se$_2$. Moreover, the presence of platinum\natoms gives rise to Rashba spin-orbit coupling in (V,Pt)Se$_2$ providing an\noriginal platform to study the interplay between ferromagnetism and spin-orbit\ncoupling in the 2D limit.",
        "positive": "Plastic-damage model for concrete in principal directions: In the present paper a plastic-damage model for concrete is discussed. Based\non the fact that for isotropic materials the elastic trial stress and the\nprojected plastic stress states have the same eigenvec-tors, the loading\nsurface is formulated in the principal stress space rather than using the\ninvariants of stress tensor. The model assumes that the directions of\northotropic damage coincide with principal directions of elastic predictor\nstress state (motivated by coaxial rotated crack model). Due to this\nassumption, the load-ing surface and the closest point projection algorithm can\nstill be formulated in the principal directions. The evolution of the inelastic\nstrain is determined using minimization principle. Damage and plastic parts of\nthe inelastic strain are separated using a scalar parameter, which is assumed\nto be stress dependent. The paper also discusses an effective numerical\nimplementation. The performance of the model is demonstrated on one\nillustrative example."
    },
    {
        "anchor": "Three-dimensional structure of a single colloidal crystal grain studied\n  by coherent x-ray diffraction: A coherent x-ray diffraction experiment was performed on an isolated\ncolloidal crystal grain at the coherence beamline P10 at PETRA III. Using\nazimuthal rotation scans the three-dimensional (3D) scattered intensity in\nreciprocal space from the sample was measured. It includes several Bragg peaks\nas well as the coherent interference around these peaks. The analysis of the\nscattered intensity reveals the presence of a plane defect in a single grain of\nthe colloidal sample. We confirm these findings by model simulations. In these\nsimulations we also analyze the experimental conditions to phase 3D diffraction\npattern from a single colloidal grain. This approach has the potential to\nproduce a high resolution image of the sample revealing its inner structure,\nwith possible structural defects.",
        "positive": "Atomistic Simulation of frictional anisotropy on quasicrystal\n  approximant surfaces: Park {\\it et al.} have reported eight times greater atomic-scale friction in\nthe periodic than in the quasiperiodic direction on the two-fold face of a\ndecagonal Al-Ni-Co quasicrystal. We present results of molecular-dynamics\nsimulations intended to elucidate mechanisms behind this giant frictional\nanisotropy. Simulations of a bare atomic-force-microscope tip on several model\nsubstrates and under a variety of conditions failed to reproduce experimental\nresults. On the other hand, including the experimental passivation of the tip\nwith chains of hexadecane thiol, we reproduce qualitatively the experimental\nanisotropy in friction, finding evidence for entrainment of the organic chains\nin surface furrows parallel to the periodic direction."
    },
    {
        "anchor": "Plasticity in irradiated FeCrAl nanopillars investigated using discrete\n  dislocation dynamics: In this paper, we investigate plasticity in irradiated FeCrAl nanopillars\nusing discrete dislocation dynamics simulations (DDD), with comparisons to\ntransmission electron microscopic (TEM) in situ tensile tests of ion and\nneutron irradiated commercial FeCrAl alloy C35M. The effects of\nirradiation-induced defects, such as a/2 111 and a 100 type loops and\ncomposition fluctuations representative of phase separation in irradiated\nFeCrAl alloys, are investigated separately as well as superposed together in\nsimulations. We explore the effects of defects on the stress-strain behavior,\nspecifically yield strength and hardening response, of FeCrAl nanopillars. Our\nsimulations confirm the widely accepted fact that irradiated alloys exhibit a\nstress-strain response with higher yield strength and hardening as compared to\nhomogeneous alloys. However, our DDD calculations reveal an atypical\nsuperposition of the hardening contributions due to composition inhomogeneity\nand irradiation loops wherein hardening due composition inhomogeneity\ncounteracts hardening due to irradiation loops at small scales. As a result, we\nobserve that the yield strength in irradiated alloys, after taking into\nconsideration the effects of both composition inhomogeneity and irradiation\nloops, is smaller than the yield strength of the alloys with only irradiation\nloops and is approximately same for the alloy with composition inhomogeneity\nalone. We identify this destructive interference in the superposition in our\nparallel TEM in situ tensile tests on unirradiated, ion irradiated, and neutron\nirradiated C35M FeCrAl alloy as well. This destructive interference in the\nhardening contributions contrasts with the widely utilized dispersed barrier\nhardening (DBH) models by the experimental community to model the hardening\ncontributions due to different irradiation induced defects.",
        "positive": "Sub-band picture of high-harmonic generation in solids: We propose a novel picture of high-harmonic generation (HHG) in solids based\non the concept of temporally changing band structures. To demonstrate the\nutility of this picture, we focus on the high-order sideband generation (HSG)\ncaused by strong terahertz (THz) and weak near-infrared (NIR) light in the\ncontext of pump-probe spectroscopy. We find that the NIR frequency dependence\nof the HSG indicates the existence of new energy levels (sub-bands) around the\nband-gap energy, which have multiple frequencies of THz light. This sub-band\npicture explains why the HSG intensity becomes a non-monotonic function of the\nTHz light amplitude. The present analysis not only reveals the origin of the\nplateau structure in HHG spectra, but also provides a connection to other\nhigh-field phenomena."
    },
    {
        "anchor": "Oblique Hanle Effect in Semiconductor Spin Transport Devices: Spin precession and dephasing (\"Hanle effect\") provides an unambiguous means\nto establish the presence of spin transport in semiconductors. We compare\ntheoretical modeling with experimental data from drift-dominated silicon\nspin-transport devices, illustrating the non-trivial consequences of employing\noblique magnetic fields (due to misalignment or intentional, fixed in-plane\nfield components) to measure the effects of spin precession. Model results are\nalso calculated for Hanle measurements under conditions of diffusion-dominated\ntransport, revealing an expected Hanle peak-widening effect induced by the\npresence of fixed in-plane magnetic bias fields.",
        "positive": "Analytical computation of the demagnetizing energy of thin film domain\n  walls: Due to its non-local nature, calculating the demagnetizing field remains the\nbiggest challenge in understanding domain structures in ferromagnetic\nmaterials. Analytical descriptions of demagnetizing effects typically\napproximate domain walls as uniformly magnetized ellipsoids, neglecting both\nthe smooth rotation of magnetization from one domain to the other and the\ninteraction between the two domains. Here, instead of the demagnetizing field,\nwe compute analytically the demagnetizing energy of a straight domain wall\ndescribed by the classical $\\tanh$ magnetization profile in a thin film with\nperpendicular magnetic anisotropy. We then use our expression for the\ndemagnetizing energy to derive an improved version of the 1D model of\nfield-driven domain wall motion, resulting in accurate expressions for\nimportant properties of the domain wall such as the domain wall width and the\nWalker breakdown field. We verify the accuracy of our analytical results by\nmicromagnetic simulations."
    },
    {
        "anchor": "Towards adiabatic-connection interpolation model with broader\n  applicability: The Adiabatic Connection Integrand Interpolation (ACII) method represents a\ngeneral path for calculating correlation energies in electronic systems within\nthe Den sity Functional Theory. ACII functionals include both exact-exchange\nand the second-order correlation energy, as well as an interpolating function\ntoward the strictly-correlated electron (SCE) regime. Several interpolating\nfunctions have been proposed in the last years targeting different properties,\nyet an accurate ACII approach with broad applicability is sti ll missing.\nRecently, we have proposed an ACII functional that was made accurate for the\nthree-dimensional (3D) uniform electron gas as well as for model metal\nclusters. In this work we present an ACII functional (named genISI2) which is\nvery accurate for both three-dimensional (3D) and two-dimensional (2D) uniform\nelectron gases and for the q uasi-2D infinite barrier model, where most of the\nexchange-correlation functionals fail badly, as well as for strongly correlated\ntwo-electrons systems. Using the exact-exchange Kohn-Sham orbitals, we have\nalso assessed the genISI2 for various molecular systems, showing a superior\nperformance with respect to the o ther ACII methods for total energies,\natomization energies, and ionization potentials. The genISI2 functional can\nthus find application in a broad range of systems and properties.",
        "positive": "Formation of Clusters of Interstitial Carbon Atoms in Graphite due to\n  Deformation Interaction and their Spatial Arrangement: Formation of clusters of interlayer interstitial carbon atoms in graphite is\nstudied by means of molecular dynamics simulation. It is shown that the\ndeformation potential is attractive for interstitials located in one interlayer\nregion and repulsive for interstitials located in different interlayer regions.\nAs a result, relatively small interstitial clusters are formed which are\narranged in a checkerboard-like order."
    },
    {
        "anchor": "Straight versus Spongy -- Effect of Tortuosity on Polymer Imbibition\n  into Nanoporous Matrices Assessed by Segmentation-Free Analysis of 3D Sample\n  Reconstructions: We comparatively analyzed imbibition of polystyrene (PS) into two\ncomplementary pore models having pore diameters of about 380 nm and\nhydroxyl-terminated inorganic-oxidic pore walls, controlled porous glass (CPG)\nand self-ordered porous alumina (AAO), by X-ray computed tomography and EDX\nspectroscopy. CPG contains continuous spongy-tortuous pore systems. AAO\ncontaining arrays of isolated straight cylindrical pores is a reference pore\nmodel with a tortuosity close to 1. Comparative evaluation of the\nspatiotemporal imbibition front evolution yields important information on the\npore morphology of a probed tortuous matrix like CPG and on the imbibition\nmechanism. To this end, pixel brightness dispersions in tomographic 3D\nreconstructions and 2D EDX maps of infiltrated AAO and CPG samples were\ncondensed into 1D brightness dispersion profiles normal to the membrane\nsurfaces. Their statistical analysis yielded positions and widths of the\nimbibition fronts without segmentation or determination of pore positions. The\nretardation of the imbibition front movement with respect to AAO reference\nsamples may be used as a descriptor for the tortuosity of a tested porous\nmatrix. The velocity of the imbibition front movements in CPG equaled\ntwo-thirds of the velocity of the imbibition front movements in AAO. Moreover,\nthe dynamics of the imbibition front broadening discloses whether porous\nmatrices are dominated by cylindrical neck-like pore segments or by nodes.\nIndependent single-meniscus movements in cylindrical AAO pores result in faster\nimbibition front broadening than in CPG, in which a morphology dominated by\nnodes results in slower cooperative imbibition front movements involving\nseveral menisci.",
        "positive": "Energetics and Dynamics of a stable Bloch point: Magnetic Bloch points (BPs) are highly confined magnetization configurations,\nthat often occur in transient spin dynamics processes. However, opposing\nchiralities of adjacent layers for instance in a FeGe bilayer stack can\nstabilize such magnetic BPs at the layer interface. These BPs configurations\nare metastable and consist of two coupled vortices (one in each layer) with\nsame circularity and opposite polarity. Each vortex is stabilized by opposite\nsign Dzyaloshinskii-Moriya interactions. This stabilization mechanism\npotentially opens the door towards BP-based spintronic applications. An open\nquestion, from a methodological point of view, is whether the Heisenberg (HB)\nmodel approach (atomistic model) as to be used to study such systems or if the\n-- computationally more efficient -- micromagnetic (MM) models can be used and\nstill obtain robust results. We are modelling and comparing the energetics and\ndynamics of a stable BP obtained using both HB and MM approaches. We find that\nan MM description of a stable BP leads qualitatively to the same results as the\nHB description, and that an appropriate mesh discretization plays a more\nimportant role than the chosen model. Further, we study the dynamics by\nshifting the BP with an applied in-plane field and investigating the relaxation\nafter switching the filed off abruptly. The precessional motion of coupled\nvortices in a BP state can be drastically reduced compared to a classical\nvortex, which may be also an interesting feature for fast and efficient\ndevices. A recent study has shown that a bilayer stack hosting BPs can be used\nto retain information [1]."
    },
    {
        "anchor": "MgyNi1-y(Hx) thin films deposited by magnetron co-sputtering: In this work we have synthesised thin films of MgyNi1-y(Hx) metal and metal\nhydride with y between 0 and 1. The films are deposited by magnetron\nco-sputtering of metallic targets of Mg and Ni. Metallic MgyNi1-y films were\ndeposited with pure Ar plasma while MgyNi1-yHx hydride films were deposited\nreactively with 30% H2 in the Ar plasma. The depositions were done with a fixed\nsubstrate carrier, producing films with a spatial gradient in the Mg and Ni\ncomposition. The combinatorial method of co-sputtering gives an insight into\nthe phase diagram of MgyNi1-y and MgyNi1-yHx, and allows us to investigate\nstructural, optical and electrical properties of the resulting alloys. Our\nresults show that reactive sputtering gives direct deposition of metal hydride\nfilms, with high purity in the case of Mg~2NiH~4. We have observed limited\noxidation after several months of exposure to ambient conditions. MgyNi1-y and\nMgyNi1-yHx films might be applied for optical control in smart windows, optical\nsensors and as a semiconducting material for photovoltaic solar cells.",
        "positive": "Stable and Metastable Structures of Cobalt on Cu(001): An ab initio\n  Study: We report results of density-functional theory calculations on the\nstructural, magnetic, and electronic properties of (1x1)-structures of Co on\nCu(001) for coverages up to two monolayers. In particular we discuss the\ntendency towards phase separation in Co islands and the possibility of\nsegregation of Cu on top of the Co-film. A sandwich structure consisting of a\nbilayer Co-film covered by 1ML of Cu is found to be the lowest-energy\nconfiguration. We also discuss a bilayer c(2x2)-alloy which may form due to\nkinetic reasons, or be stabilized at strained surface regions. Furthermore, we\nstudy the influence of magnetism on the various structures and, e.g., find that\nCo adlayers induce a weak spin-density wave in the copper substrate."
    },
    {
        "anchor": "Face-centered-cubic titanium in Ti/Al multilayer thin films synthesized\n  by magnetron sputtering technique: Ti/Al multilayer thin films with precise thickness have been deposited using\na combination of dc and rf magnetron sputtering techniques. Cross-sectional\ntransmission electron microscopy (TEM) revealed unmixed fifteen parallel and\nalternate layers of Ti and Al with sharp interfaces, each measuring 27 nm and\n15 nm in thickness, respectively. The Ti layer was composed of hcp and fcc\nphases while the Al layer was fcc. Both x-ray diffraction (XRD) and selected\narea electron diffraction (SAED) analysis confirmed the identity of these\nphases. Detection of fcc-Ti in as-deposited the Ti/Al multilayer thin film by\nXRD established that the fcc-Ti phase is not an artifact of TEM sample\npreparation, as have been envisaged by some of the previous researchers. The\nfcc-Ti phase appeared when dual rf guns were used for Ti deposition and the\ndiffraction peak intensity corresponding to fcc phase increased when the gun\npower was raised. A modified equation of state based thermodynamic analysis\nconfirmed that the formation of hcp phase as opposed to the thermodynamically\nstable fcc phase of pure Ti is due to crystallite size reduction and not\nimpurity driven.",
        "positive": "Planar Hall effect in Y3Fe5O12(YIG)/IrMn films: The planar Hall effect of IrMn on an yttrium iron garnet (YIG = Y3Fe5O12) was\nmeasured in the magnetic field rotating in the film plane. The magnetic field\nangle dependence of planar Hall resistance (PHR) has been observed in YIG/IrMn\nbilayer at different temperatures, while the GGG/IrMn (GGG= Gd3Ga5O12) shows\nconstant PHR for different magnetic field angles at both 10 K and 300 K. This\nprovides evidence that IrMn has interfacial spins which can be led by FM in\nYIG/IrMn structure. A hysteresis can be observed in PHR-magnetic field angle\nloop of YIG/IrMn films at 10 K, indicating the irreversible switching of IrMn\ninterfacial spins at low temperature."
    },
    {
        "anchor": "Thermodynamic model of hardness: Particular case of boron-rich solids: A number of successful theoretical models of hardness have been developed\nrecently. A thermodynamic model of hardness, which supposes the intrinsic\ncharacter of correlation between hardness and thermodynamic properties of\nsolids, allows one to predict hardness of known or even hypothetical solids\nfrom the data on Gibbs energy of atomization of the elements, which implicitly\ndetermine the energy density per chemical bonding. The only structural data\nneeded is the coordination number of the atoms in a lattice. Using this\napproach, the hardness of known and hypothetical polymorphs of pure boron and a\nnumber of boron-rich solids has been calculated. The thermodynamic\ninterpretation of the bonding energy allows one to predict the hardness as a\nfunction of thermodynamic parameters. In particular, the excellent agreement\nbetween experimental and calculated values has been observed not only for the\nroom- temperature values of the Vickers hardness of stoichiometric compounds,\nbut also for its temperature and concentration dependencies.",
        "positive": "Ab initio study of NaSrSb and NaBaSb as potential thermoelectric\n  prospects: Zintl phases are excellent thermoelectric prospects to put the waste heat to\ngood use. In the quest of the same, using first-principles methods combined\nwith Boltzmann transport theory, we explored two recent phases NaSrSb and\nNaBaSb. We found low lattice thermal conductivity of 1.9 and 1.3 W m$^{-1}$\nK$^{-1}$ at 300~K for NaSrSb and NaBaSb, respectively, which are of the same\norder as other potential Zintl phases such as Sr$_3$AlSb$_3$ and BaCuSb. We\naccount for such low values to short phonon lifetimes, small phonon group\nvelocities, and lattice anharmonicity in the crystal structure. The calculated\nelectrical transport parameters based on acoustic deformation potential,\nionized impurity, and polar optical phonon scattering mechanisms reveal large\nSeebeck coefficients for both materials. Further, we obtain a high figure of\nmerit of ZT$\\sim$2.0 at 900~K for \\textit{n}-type NaSrSb. On the other hand,\nthe figure of merit of \\textit{n}-type NaBaSb surpasses the unity. We are\noptimistic about our findings and believe our work would set a basis for future\nexperimental investigations."
    },
    {
        "anchor": "Z2Pack: Numerical Implementation of Hybrid Wannier Centers for\n  Identifying Topological Materials: The intense theoretical and experimental interest in topological insulators\nand semimetals has established band structure topology as a fundamental\nmaterial property. Consequently, identifying band topologies has become an\nimportant, but often challenging problem, with no exhaustive solution at the\npresent time. In this work we compile a series of techniques, some previously\nknown, that allow for a solution to this problem for a large set of the\npossible band topologies. The method is based on tracking hybrid Wannier charge\ncenters computed for relevant Bloch states, and it works at all levels of\nmaterials modeling: continuous k.p models, tight-binding models and ab initio\ncalculations. We apply the method to compute and identify Chern, Z2 and\ncrystalline topological insulators, as well as topological semimetal phases,\nusing real material examples. Moreover, we provide a numerical implementation\nof this technique (the Z2Pack software package) that is ideally suited for\nhigh-throughput screening of materials databases for compounds with non-trivial\ntopologies. We expect that our work will allow researchers to: (a) identify\ntopological materials optimal for experimental probes, (b) classify existing\ncompounds and (c) reveal materials that host novel, not yet described,\ntopological states.",
        "positive": "Anomalous Hall effect and negative longitudinal magnetoresistance in\n  half-Heusler topological semimetal candidates TbPtBi and HoPtBi: Half-Heusler compounds have attracted significant attention because of their\ntopologically non-trivial electronic structure, which leads to unusual electron\ntransport properties. We thoroughly investigated the magnetotransport\nproperties of high-quality single crystals of two half-Heusler phases, TbPtBi\nand HoPtBi, in pursuit of the characteristic features of topologically\nnon-trivial electronic states. Both studied compounds are characterized by the\ngiant values of transverse magnetoresistance with no sign of saturation in\nmagnetic field up to 14 T. HoPtBi demonstrates the Shubnikov-de Haas effect\nwith two principal frequencies, indicating a complex Fermi surface; the\nextracted values of carrier effective masses are rather small, $0.18\\,m_e$ and\n$0.27\\,m_e$. The investigated compounds exhibit negative longitudinal\nmagnetoresistance and anomalous Hall effect, which likely arise from a nonzero\nBerry curvature. Both compounds show strongly anisotropic magnetoresistance,\nthat in HoPtBi exhibits a butterfly-like behavior."
    },
    {
        "anchor": "Emergent half-metal with mixed structural order in (111)-oriented\n  (LaMnO$_3$)$_{2n}$|(SrMnO$_3$)$_n$ superlattices: Using first-principles techniques, we study the structural, magnetic and\nelectronic properties of (111)-oriented\n(LaMnO$_3$)$_{2n}$$\\vert$(SrMnO$_3$)$_{n}$ superlattices of varying thickness\n($n=2,4,6$). We find that the properties of the thinnest superlattice ($n=2$)\nare similar to the celebrated half-metallic ferromagnetic alloy\nLa$_{2/3}$Sr$_{1/3}$MnO$_3$, with quenched Jahn-Teller distortions. At\nintermediate thickness ($n=4$), the $a^{-}a^{-}a^{-}$ tilting pattern\ntransitions to the $a^{-}a^{-}c^{+}$ tilting pattern, driven by the lattice\ndegrees of freedom in the LaMnO$_3$ region. The emergence of the Jahn-Teller\nmodes and the spatial extent needed for their development play a key role in\nthis structural transition. For the largest thickness considered ($n=6$), we\nunveil an emergent separation of Jahn-Teller and volume-breathing orders in the\nground-state structure with the $a^{-}a^{-}c^{+}$ tilting pattern, whereas it\nvanishes in the antiferromagnetic configurations. The ground state of all\nsuperlattices is half-metallic ferromagnetic, not affected by the underlying\nseries of structural transitions. Overall, these results outline a\nthickness-induced crossover between the physical properties of bulk\nLa$_{2/3}$Sr$_{1/3}$MnO$_3$ and bulk LaMnO$_3$.",
        "positive": "Experiments and Modeling of Mass Transport Phenomena in SiGe Devices: Recent experiments and continuum modeling work on dopant diffusion and\nsegregation, Si-Ge interdiffusion, and defect engineering in SiGe material\nsystems are reviewed. Doping impact on Ge thin film quality and interdiffusion\nis also discussed. These are relevant to SiGe-based semiconductor devices\nincluding SiGe hetero-junction bipolar transistors, metal-oxidesemiconductor\nfield-effect transistors, and Ge-on-Si based photonic devices."
    },
    {
        "anchor": "InAs Heteroepitaxy on Nanopillar-Patterned GaAs (111)A: Heteroepitaxy on nanopatterned substrates is a means of defect reduction at\nsemiconductor heterointerfaces by exploiting substrate compliance and enhanced\nelastic lattice relaxation resulting from reduced dimensions. We explore this\npossibility in the InAs/GaAs(111)A system using a combination of nanosphere\nlithography and reactive ion etching of the GaAs(111)A substrate for\nnano-patterning of the substrate, yielding pillars with honeycomb and hexagonal\narrangements and varied nearest neighbor distances. Substrate patterning is\nfollowed by MBE growth of InAs at temperatures of 150 - 350 C and growth rates\nof 0.011 nm/s and 0.11 nm/s. InAs growth in the form of nano-islands on the\npillar tops is achieved by lowering the adatom migration length by choosing a\nlow growth temperature of 150 C at the growth rate 0.011 nm/s. The choice of a\nhigher growth rate of 0.11 nm/s results in higher InAs island nucleation and\nthe formation of hillocks concentrated at the pillar bases due to a further\nreduction of adatom migration length. A common feature of the growth morphology\nfor all other explored conditions is the formation of merged hillocks or\npyramids with well-defined facets due to the presence of a concave surface\ncurvature at the pillar bases acting as adatom sinks.",
        "positive": "Spin injection into multilayer graphene from highly spin-polarized\n  Co2FeSi Heusler alloy: We demonstrate electrical spin injection into multilayer graphene (MLG) in a\nlateral spin valve device from a highly spin-polarized Co2FeSi (CFS) Huesler\nelectrode. Exfoliated MLG was transferred onto pre-patterned epitaxial CFS\nwires grown on an Si(111) substrate by a polymer-based transfer method. This\nmethod enabled us to fabricate multiple single-crystal CFS electrodes in\ncontact with MLG. Electrical spin injection from CFS to MLG was detected\nthrough non-local magnetoresistance (MR) measurement. A non-local spin signal\nof 430 ohm was observed; this is the largest value among all reported non-local\nMR values in graphene-based devices."
    },
    {
        "anchor": "Thickness Dependence of Magneto-transport Properties in Tungsten\n  Ditelluride: We investigate the electronic structure of tungsten ditelluride (WTe$_2$)\nflakes with different thicknesses in magneto-transport studies. The\ntemperature-dependent resistance and magnetoresistance (MR) measurements both\nconfirm the breaking of carrier balance induced by thickness reduction, which\nsuppresses the `turn-on' behavior and large positive MR. The Shubnikov-de-Haas\noscillation studies further confirm the thickness-dependent change of\nelectronic structure of WTe$_2$ and reveal a possible temperature-sensitive\nelectronic structure change. Finally, we report the thickness-dependent\nanisotropy of Fermi surface, which reveals that multi-layer WTe$_2$ is an\nelectronic 3D material and the anisotropy decreases as thickness decreases.",
        "positive": "A machine learning potential-based generative algorithm for on-lattice\n  crystal structure prediction: We propose a method for crystal structure prediction based on a new structure\ngeneration algorithm and on-lattice machine learning interatomic potentials.\nOur algorithm generates the atomic configurations assigning atomic species to\nsites of the given lattice, and uses cluster expansion or low-rank potential to\nevaluate their energy. We demonstrate two benefits of such approach. First, our\nstructure generation algorithm offers a ``smart'' configurational space\nsampling, targeting low-energy structures which significantly reduces\ncomputational costs. Second, the application of machine learning interatomic\npotentials significantly reduces the number of DFT calculations. We discuss how\nour algorithm resembles the latent diffusion models for image generation. We\ndemonstrate the efficiency of our method by constructing the convex hull of\nNb-Mo-Ta-W system, including binary and ternary Nb-W and Mo-Ta-W subsystems. We\nfound new binary, ternary, and quaternary stable structures that are not\nreported in the AFLOW database which we choose as our baseline. Due to the\ncomputational efficiency of our method we anticipate that it can pave the way\ntowards efficient high-throughput discovery of multicomponent materials."
    },
    {
        "anchor": "Glass tube cutting with aberration-corrected non-diffracting ultrashort\n  laser pulses: The separation of complex inner and outer contours of glass articles with\ncurved surfaces using ultrashort pulsed lasers is reported. Single-pass,\nfull-thickness modifications along the entire substrate are achieved using a\nprocessing optics that allows for beam shaping of non-diffracting beams and,\nadditionally, for aberration compensation of phase distortions occurring at the\ncurved interface. The glass articles finally separated by thermal stress or via\nselective etching meet the demands of the medical industry in terms of\nmicro-debris, surface quality and processing speed.",
        "positive": "Universality behind Basquin's law of fatigue: One of the most important scaling laws of time dependent fracture is\nBasquin's law of fatigue, namely, that the lifetime of the system increases as\na power law with decreasing external load amplitude, $t_f\\sim\n\\sigma_0^{-\\alpha}$, where the exponent $\\alpha$ has a strong material\ndependence. We show that in spite of the broad scatter of the Basquin exponent\n$\\alpha$, the fatigue fracture of heterogeneous materials exhibits intriguing\nuniversal features. Based on stochastic fracture models we propose a generic\nscaling form for the macroscopic deformation and show that at the fatigue limit\nthe system undergoes a continuous phase transition when changing the external\nload. On the microlevel, the fatigue fracture proceeds in bursts characterized\nby universal power law distributions. We demonstrate that in a range of\nsystems, including deformation of asphalt, a realistic model of deformation,\nand a fiber bundle model, the system dependent details are contained in\nBasquin's exponent for time to failure, and once this is taken into account,\nremaining features of failure are universal."
    },
    {
        "anchor": "Graphene growth on h-BN by Molecular Beam Epitaxy: The growth of single layer graphene nanometer size domains by solid carbon\nsource molecular beam epitaxy on hexagonal boron nitride (h-BN) flakes is\ndemonstrated. Formation of single-layer graphene is clearly apparent in Raman\nspectra which display sharp optical phonon bands. Atomic-force microscope\nimages and Raman maps reveal that the graphene grown depends on the surface\nmorphology of the h-BN substrates. The growth is governed by the high mobility\nof the carbon atoms on the h-BN surface, in a manner that is consistent with\nvan der Waals epitaxy. The successful growth of graphene layers depends on the\nsubstrate temperature, but is independent of the incident flux of carbon atoms.",
        "positive": "Melting of gold by ultrashort laser pulses: Advanced two-temperature\n  modeling and comparison with surface damage experiments: The ultrafast laser-induced solid-liquid phase transition in metals is still\nnot clearly understood and its accurate quantitative description remains a\nchallenge. Here we systematically investigated, both experimentally and\ntheoretically, the melting of gold by single femto- and picosecond\nnear-infrared laser pulses. Two laser systems with wavelengths of 800 and 1030\nnm and pulse durations ranging from 124 fs to 7 ps were used and the damage and\nablation thresholds were determined for each irradiation condition. The\ntheoretical analysis was based on two-temperature modeling. Different\nexpressions for the electron-lattice coupling rate and contribution of\nballistic electrons were examined. In addition, the number of free electrons\ninvolved in the optical response is suggested to be dependent on the laser\nintensity and the influence of the fraction of involved electrons on the damage\nthreshold was investigated. Only one combination of modelling parameters was\nable to describe consistently all the measured damage thresholds. Physical\narguments are presented to explain the modeling results."
    },
    {
        "anchor": "Hydrogen storage in MOF-5: A van der Waals density functional theory\n  study: Physisorption of hydrogen molecules in metal-organic frameworks (MOFs)\nprovides a promising way for hydrogen storage, in which the van der Waals (vdW)\ninteraction plays an important role but cannot described by the density\nfunctional theory (DFT). By using the vdW density functional (vdW-DF) method,\nwe investigate systematically the binding energies of hydrogen molecules in\nMOF-5 crystal. We first examine the accuracy of this methodology by comparing\nits results with those from the correlated quantum chemistry methods for\nseveral fragment models cut out from the crystal. Good comparable accuracy is\nfound. By performing calculations for the true crystal structure adsorbing one\nor multiple H$_2$ in the primitive cell, we show that these fragment models\nwhich have been focused previously cannot represent well the property of the\ncrystal which cannot, however, be dealt with by the quantum chemistry methods.\nIt is found that the binding energy with the organic linker is much smaller\nthan with the metal oxide corner, which limits the H$_2$ loading. We show that\nthis can be improved significantly (from 5.50 to 10.39 kJ/mol) by replacing the\nH atoms of the organic linker with F atoms which cause extra electrostatic\ninteraction.",
        "positive": "Kagome van-der-Waals Pd3P2S8 with flat band: With the advanced investigations into low-dimensional systems, it has become\nessential to find materials having interesting lattices that can be exfoliated\ndown to monolayer. One particular important structure is a kagome lattice with\nits potentially diverse and vibrant physics. We report a van-der-Waals kagome\nlattice material, Pd3P2S8, with several unique properties such as an intriguing\nflat band. The flat band is shown to arise from a possible compact-localized\nstate of all five 4d orbitals of Pd. The diamagnetic susceptibility is\nprecisely measured to support the calculated susceptibility obtained from the\nband structure. We further demonstrate that Pd3P2S8 can be exfoliated down to\nmonolayer, which ultimately will allow the possible control of the localized\nstates in this two-dimensional kagome lattice using the electric field gating."
    },
    {
        "anchor": "Correlation Effects on Magnetic Anisotropy in Fe and Ni: We calculate magnetic anisotropy energy of Fe and Ni by taking into account\nthe effects of strong electronic correlations, spin-orbit coupling, and\nnon-collinearity of intra-atomic magnetization. The LDA+U method is used and\nits equivalence to dynamical mean-field theory in the static limit is derived.\nThe effects of strong correlations are studied along several paths in $(U,J)$\nparameter space. Both experimental magnitude of MAE and direction of\nmagnetization are predicted correctly near $U=1.9 eV$, $J=1.2 eV$ for Ni and\n$U=1.2 eV$, $J=0.8 eV$ for Fe. The modified one-electron spectra by strong\ncorrelations are emphasized in conjunction with magnetic anisotropy.",
        "positive": "Direct and Indirect methods of electrocaloric effect determination and\n  energy storage calculation in (Na0.8K0.2)0.5Bi0.5TiO3 ceramic: The coexistence of multiple structural phases and field induced short-range\nto long-range order transition in ferroelectric materials, leads to a strong\nelectrocaloric effect (ECE) and electrical energy storage density (Wrec) in the\nvicinity of ferroelectric to non-ergodic phase transition in NKBT ceramic.\nStructural analysis using X-ray diffraction, Raman spectroscopy and TEM studies\nascertained the coexistence of tetragonal (P4mm) and rhombohedral (R3c) phases.\nDielectric study has revealed a critical slowing down of polar domain dynamics\nbelow a diffuse phase transition. Present investigation reports ECE in\nlead-free (Na0.8K0.2)0.5Bi0.5TiO3 (NKBT) ceramic by direct and indirect\nmethods, which confirm the multifunctional nature of NKBT and its usefulness\nfor applications in refrigeration and energy storage. A direct method of EC\nmeasurement in NKBT ceramic exhibits significant adiabatic temperature change\n({\\Delta}T) ~ 1.10 K and electrocaloric strength ({\\xi}) ~ 0.55 Kmm/kV near the\nferroelectric to non-ergodic phase transition at an external applied field of\n20 kV/cm. A highest recoverable energy (Wrec) ~ 0.78 J/cm3 and electrical\nstorage efficiency ({\\eta}) ~ 86% are achieved at 423 K and an applied field of\n20 kV/cm. This behavior is ascribed to the delicate balance between the field\ninduced order-disordered transition and the thermal energy needed to disrupt\nfield induced co-operative interaction."
    },
    {
        "anchor": "Anti-$\\mathcal{PT}$ flatbands: We consider tight-binding single particle lattice Hamiltonians which are\ninvariant under an antiunitary antisymmetry: the anti-$\\mathcal{PT}$ symmetry.\nThe Hermitian Hamiltonians are defined on $d$-dimensional non-Bravais lattices.\nFor an odd number of sublattices, the anti-$\\mathcal{PT}$ symmetry protects a\nflatband at energy $E = 0$. We derive the anti-$\\mathcal{PT}$ constraints on\nthe Hamiltonian and use them to generate examples of generalized kagome\nnetworks in two and three lattice dimensions. Furthermore, we show that the\nanti-$\\mathcal{PT}$ symmetry persists in the presence of uniform DC fields and\nensures the presence of flatbands in the corresponding irreducible\nWannier-Stark band structure. We provide examples of the Wannier-Stark band\nstructure of generalized kagome networks in the presence of DC fields, and\ntheir implementation using Floquet engineering.",
        "positive": "Magnetic contrast layers with functional SiO2 coatings for soft matter\n  studies with polarised neutron reflectometry: This study introduces silicon substrates with a switchable magnetic contrast\nlayer (MCL) for polarised neutron reflectometry experiments (PNR) at\nsolid/liquid interface to study soft matter surface layers. The advantage with\nneutron reflectometry (NR) data is that structural and compositional\ninformation can be enhanced by using different isotopic contrast on the same\nsample. This approach is normally referred to as contrast matching, which can\nbe achieved by using solvents with different isotopic contrast, e. g. different\nH2O/D2O ratio, and/or by selective deuteration of the molecules. However, some\nsoft matter system might be perturbed by this approach, or it might not be\npossible, particularly for biological samples. In this scenario, solid\nsubstrates with a MCL are an appealing alternative, as the magnetic contrast\nwith the substrate can be used to partially recover the information on the\nsample structure. More specifically, in this study, a magnetically soft Fe\nlayer coated with SiO2 was produced by ion-beam sputter deposition on silicon\nsubstrates of different sizes. The structure was evaluated using XRR, AFM, VSM,\nand PNR. The collected data showed high quality and repeatability of the MCL\nparameters, regardless of the substrate size and thickness of the capping SiO2\nlayers. As compared to other kinds of substrates with MCL layer previously\nproposed, which used Au capping layer, the SiO2 capping layer allows to\nreproduce the typical surface of standard silicon substrate used for NR\nexperiment and compatible with a large variety of soft matter samples. We\ndemonstrated such application, by using ready-to-measure 50*50*10 mm3\nsubstrates in PNR experiments for the characterisation of a lipid bilayer in a\nsingle solvent contrast. Overall, the article highlights the potential of PNR\nwith MCL for investigation of soft matter samples."
    },
    {
        "anchor": "Dynamic and adaptive mesh-based graph neural network framework for\n  simulating displacement and crack fields in phase field models: Fracture is one of the main causes of failure in engineering structures.\nPhase field methods coupled with adaptive mesh refinement (AMR) techniques have\nbeen widely used to model crack propagation due to their ease of implementation\nand scalability. However, phase field methods can still be computationally\ndemanding making them unfeasible for high-throughput design applications.\nMachine learning (ML) models such as Graph Neural Networks (GNNs) have shown\ntheir ability to emulate complex dynamic problems with speed-ups orders of\nmagnitude faster compared to high-fidelity simulators. In this work, we present\na dynamic mesh-based GNN framework for emulating phase field simulations of\ncrack propagation with AMR for different crack configurations. The developed\nframework - ADAPTive mesh-based graph neural network (ADAPT-GNN) - exploits the\nbenefits of both ML methods and AMR by describing the graph representation at\neach time-step as the refined mesh itself. Using ADAPT-GNN, we predict the\nevolution of displacement fields and scalar damage field (or phase field) with\nhigh accuracy compared to conventional phase field fracture model. We also\ncompute crack stress fields with high accuracy using the predicted\ndisplacements and phase field parameter. Finally, we observe speed up of 15-36x\ncompared to serial execution of the phase field model.",
        "positive": "Ni-based nanoalloys: Towards thermally stable highly magnetic materials: Molecular dynamics simulations and density functional theory calculations\nhave been used to demonstrate the possibility of preserving high spin states of\nthe magnetic cores within Ni-based core-shell bimetallic nanoalloys over a wide\nrange of temperatures. We show that, unlike the case of Ni-Al clusters, Ni-Ag\nclusters preserve high spin states (up to 8 $\\mu_{\\mathrm{B}}$ in case of\nNi$_{13}$Ag$_{32}$ cluster) due to small hybridization between the electronic\nlevels of two species. Intriguingly, such clusters are also able to maintain\ngeometrical and electronic integrity of their cores at temperatures up to 1000\nK (e.g. for Ni$_{7}$Ag$_{27}$ cluster). Furthermore, we also show the\npossibility of creating ordered arrays of such magnetic clusters on a suitable\nsupport by soft-landing pre-formed clusters on the surface, without introducing\nmuch disturbance in geometrical and electronic structure of the cluster. We\nillustrate this approach with the example of Ni$_{13}$Ag$_{38}$ clusters\nadsorbed on the Si(111)-(7$\\times$7) surface, which, having two distinctive\nhalves to the unit cell, acts as a selective template for cluster deposition."
    },
    {
        "anchor": "Anomalous pressure dependence of the atomic displacements in the relaxor\n  ferroelectric PbMg$_{1/3}$Ta$_{2/3}$O$_3$: The crystal structure of the PbMg$_{1/3}$Ta$_{2/3}$O$_3$ (PMT) relaxor\nferroelectric was studied under hydrostatic pressure up to $\\sim 7$ GPa by\nmeans of powder neutron diffraction. We find a drastic pressure-induced\ndecrease of the lead displacement from the inversion centre which correlates\nwith an increase by $\\sim$ 50 % of the anisotropy of the oxygen temperature\nfactor. The vibrations of the Mg/Ta are, in contrast, rather pressure\ninsensitive. We attribute these changes being responsible for the previously\nreported pressure-induced suppression of the anomalous dielectric permittivity\nand diffuse scattering in relaxor ferroelectrics.",
        "positive": "Kinetics of the lattice response to hydrogen absorption in thin Pd and\n  CoPd films: Hydrogen can penetrate reversibly a number of metals, occupy the interstitial\nsites and cause large expansion of the crystal lattice. The question discussed\nhere is whether the kinetics of the structural response matches hydrogen\nabsorption. We show that thin Pd and CoPd films exposed to a relatively rich\nhydrogen atmosphere (4% H2) inflate irreversibly, demonstrate the controllable\nshape memory, and duration of the process can be orders of magnitude longer\nthan hydrogen absorption. The dynamics of the out-of-equilibrium plastic creep\nis well described by the Avrami - type model of the nucleation and lateral\ndomain wall expansion of the swelled sites."
    },
    {
        "anchor": "Microscopic mechanism of structural and volume relaxation below glass\n  transition temperature in a soda-lime silicate glass revealed by Raman\n  spectroscopy and its first principle calculations: To elucidate the atomistic origin of volume relaxation in soda-lime silicate\nglass annealed below the glass transition temperature (Tg), the experimental\nand calculated Raman spectra were compared. By decomposing the calculated Raman\nspectra into a specific group of atoms, we found that the Raman peak at 1050\ncm-1 corresponds to bridging oxygen with a small Si-O-Si bond angle. The\nexperimental Raman spectra indicated that, during annealing below Tg, a\nhomogenization reaction Q2+Q4->2Q3 proceeds in the early stage of structural\nrelaxation. Then, the Si-O-Si units with relatively small angles decrease even\nin the later stages, which is first evidence of ring deformation causing volume\nrelaxation of soda-lime silicate glass because decreasing small Si-O-Si angles\ncorresponds to the reduce of acute O-O-O angle in a ring and can expand the\nspace inside the rings, and Na can be inserted into the ring center. In\nconclusion the ring deformation and Na displacement is the origin of the volume\nrelaxation of soda-lime silicate glass below Tg.",
        "positive": "Magnetostrictive thin films for microwave spintronics: Multiferroic composite materials, consisting of coupled ferromagnetic and\npiezoelectric phases, are of great importance in the drive towards creating\nfaster, smaller and more energy efficient devices for information and\ncommunications technologies. Such devices require thin ferromagnetic films with\nlarge magnetostriction and narrow microwave resonance linewidths. Both\nproperties are often degraded, compared to bulk materials, due to structural\nimperfections and interface effects in the thin films. We report the\ndevelopment of single crystal thin films of Galfenol (Fe81Ga19) with\nmagnetostriction as large as the best reported values for bulk material. This\nallows the magnetic anisotropy and microwave resonant frequency to be tuned by\nvoltage-induced strain, with a larger magnetoelectric response and a narrower\nlinewidth than any previously reported Galfenol thin films. The combination of\nthese properties make the single crystal thin films excellent candidates for\ndeveloping tunable devices for magnetic information storage, processing and\nmicrowave communications."
    },
    {
        "anchor": "Spectroscopic mapping of local structural distortions in ferroelectric\n  PbTiO3/SrTiO3 superlattices at the unit-cell scale: The local structural distortions in polydomain ferroelectric PbTiO3/SrTiO3\nsuperlattices are investigated by means of high spatial and energy resolution\nelectron energy loss spectroscopy combined with high angle annular dark field\nimaging. Local structural variations across the interfaces have been identified\nwith unit cell resolution through the analysis of the energy loss near edge\nstructure of the Ti-L2,3 and O-K edges. Ab-initio and multiplet calculations of\nthe Ti-L2,3 edges provide unambiguous evidence for an inhomogeneous\npolarization profile associated with the observed structural distortions across\nthe superlattice.",
        "positive": "Effect of processing conditions on the thermal and electrical\n  conductivity of poly (butylene terephthalate) nanocomposites prepared via\n  ring-opening polymerization: Successful preparation of polymer nanocomposites, exploiting graphene-related\nmaterials, via melt mixing technology requires precise design, optimization and\ncontrol of processing. In the present work, the effect of different processing\nparameters during the preparation of poly (butylene terephthalate)\nnanocomposites, through ring-opening polymerization of cyclic butylene\nterephthalate in presence of graphite nanoplatelets (GNP), was thoroughly\naddressed. Processing temperature (240{\\deg}C or 260{\\deg}C), extrusion time (5\nor 10 minutes) and shear rate (50 or 100 rpm) were varied by means of a full\nfactorial design of experiment approach, leading to the preparation of\npolybutylene terephthalate/GNP nanocomposite in 8 different processing\nconditions. Morphology and quality of GNP were investigated by means of\nelectron microscopy, X-ray photoelectron spectroscopy, thermogravimetry and\nRaman spectroscopy. Molecular weight of the polymer matrix in nanocomposites\nand nanoflake dispersion were experimentally determined as a function of the\ndifferent processing conditions. The effect of transformation parameters on\nelectrical and thermal properties was studied by means of electrical and\nthermal conductivity measurement. Heat and charge transport performance\nevidenced a clear correlation with the dispersion and fragmentation of the GNP\nnanoflakes; in particular, gentle processing conditions (low shear rate, short\nmixing time) turned out to be the most favourable condition to obtain high\nconductivity values."
    },
    {
        "anchor": "Driving force induced transition in thermal behavior of grain boundary\n  migration in Ni: Grain boundary (GB) migration exhibits intriguing anti-thermal behavior (or\nnon-Arrhenius behavior), with the temperature and driving force playing crucial\nroles. Through atomistic simulations on nickel bicrystals, we investigate the\nchange in GB mobility with variations in both temperature and driving force.\nOur results reveal that the GB mobility initially increases with temperature\nand subsequently decreases after reaching the transition temperature (Ttrans),\nand, notably, Ttrans exhibits a linear relationship with the activation energy\n(Q) associated with GB migration. By modulating the driving force, we found\nthat the driving force could effectively lower Q, resulting in the shift of\nTtrans towards lower temperatures. Additionally, higher driving forces were\nfound to activate more migration modes at lower temperatures, potentially\nleading to a transition in the thermal behavior of GB migration. Our work\nsupports the existing theoretical models for GB migration based on both\nclassical thermal activation and disconnection nucleation. Furthermore, we\nrefined the existing model by incorporating the influence of the driving force.\nThe modified model can not only describe the effect of driving force on the\nthermal behavior of GB migration but also accounts for the observed\n\"anti-driving force\" phenomenon in GB migration. Our research has the potential\nto offer valuable insights for investigating realistic GB migration under more\nintricate constraints and environments.",
        "positive": "Ternary Hypervalent Silicon Hydrides via Lithium at High Pressure: Hydrogen is rarely observed as ligand in hypervalent species, however, we\nfind that high-pressure hydrogenation may stabilise hypervalent hydrogen-rich\nmaterials. Focussing on ternary silicon hydrides via lithium doping, we find\nanions composed of hypervalent silicon with H ligands formed under high\npressure. Our results reveal two new hypervalent anions: layered-SiH$_{5}^{-}$\nand tricapped trigonal prismatic SiH$_{6}^{2-}$. These differ from octahedral\nSiH$_{6}^{2-}$ described in earlier studies. In addition, there are further\nhydrogen-rich structures Li$_{3}$SiH$_{10}$ and Li$_{2}$SiH$_{6+\\delta}$ which\nmay be stabilised at high pressure. Our work provides pointers to future\ninvestigations on hydrogen-rich materials."
    },
    {
        "anchor": "Oxygen non-stoichiometry and the origin of Na ion ordering in\n  gamma-NaxCoO2: The impact of oxygen deficiency on physical properties of Na2/3CoO2-x has\nbeen investigated. From the combined thermogravimetric, magnetic susceptibility\nand synchrotron X-ray Laue diffraction studies, it is demonstrated that\nNa2/3CoO2 shows no superlattice ordering due to Na ions; however Na2/3CoO1.98,\nwhich has the same Co valence as that of Na0.71CoO2, shows nearly identical\nmagnetic and transport properties and the same simple hexagonal superlattice\nordering of sqrt(12)a. It is proposed that the Na ion ordering found in\nNa2/3CoO1.98 is identical to the ideal Na0.71CoO2 of large sqrt(12)a x\nsqrt(12)a x 3c superlattice but with additional Na vacancies which are bound to\nthe oxygen defects at room temperature. We conclude that oxygen vacancies play\na key role in stabilizing the superlattice structure and must be accounted for\nin its modeling.",
        "positive": "Effect of Cobalt Content on the Electrochemical Properties and\n  Structural Stability of NCA Type Cathode Materials: At present, the most common type of cathode materials, NCA\n[Li_(1-x)Ni_(0.80)Co_(0.15)Al_(0.05)O_(2), x = 0 to 1], have a very high\nconcentration of cobalt. Since cobalt is toxic and expensive, the existing\ndesign of cathode materials is neither cost-effective nor environmentally\nbenign. We have performed density functional theory (DFT) calculations to\ninvestigate electrochemical, electronic, and structural properties of four\ntypes of NCA cathode materials with the simultaneous decrease in Co content\nalong with the increase in Ni content. Our results show that even if the cobalt\nconcentration is significantly decreased from 16.70 % (NCA_I) to 4.20 %\n(NCA_IV), variation in intercalation potential and specific capacity is not\nsignificant. For example, in case of 50% Li concentration, the voltage drop is\nonly ~17% while the change in specific capacity is negligible. Moreover, we\nhave also explored the influence of sodium doping in the intercalation site on\nthe electrochemical, electronic, and structural properties. By considering two\nextreme cases of NCAs (i.e., with highest and lowest Co content: NCA_I and\nNCA_IV respectively), we have demonstrated the importance of Na doping from the\nstructural and electronic point of view. Our results provide insight into the\ndesign of environmentally benign, low-cost cathode materials with reduced\ncobalt concentration."
    },
    {
        "anchor": "Dynamic nanoindentation and short-range order in equiatomic NiCoCr\n  medium entropy alloy lead to novel density wave ordering: Chemical short-range order (CSRO) is believed to be a key contributor to the\nexceptional properties of multicomponent alloys. However, direct validation and\nconfirmation of CSRO has been highly elusive in most compounds. Recent studies\nfor equiatomic NiCoCr alloys have shown that thermal treatments (i.e.,\nannealing/aging) may facilitate and manipulate CSRO. In this work, by using\nmolecular simulations, we show that nanomechanical probes, such as\nnanoindentation, may be utilized towards further manipulation of CSRO,\nproviding explicit validation pathways. By using well established interatomic\npotentials, we perform hybrid Molecular-Dynamics/Monte-Carlo (MD/MC) at room\ntemperature to demonstrate that particular dwell nanoindentation protocols can\nlead, through thermal MC equilibration, to the reorganization of CSRO under the\nindenter tip, to a density-wave stripe pattern (DWO). We characterize the novel\nDWO structures, that are directly correlated to incipient SRO but are highly\nanisotropic and dependent on local, nanoindentation-induced stress\nconcentrations, and we show how they deeply originate from the peculiarities of\nthe interatomic potentials. Furthermore, we show that the DWO patterns\nconsistently scale up with the incipient plastic zone under the indenter tip,\njustifying the observation of the DWO patterning at any experimentally feasible\nnanoindentation depth.",
        "positive": "A Rule of Solute Segregation at Grain Boundaries: The control of solute segregation at grain boundaries (GBs) is essential in\nengineering alloy properties, however the structure-activity relationship of\nthe key parameter-the segregation energies-still remains elusive. Here we\npropose the electronic and geometric descriptors of GB segregation based on the\nvalence, electronegativity and size of solutes and the non-local coordination\nnumber of free surfaces, with which we build a predictive framework to\ndetermine the segregation energies across different solutes, matrices, GB\nstructures and segregation sites. This framework uncovers not only the coupling\nrule of solutes and matrices in GB segregation, but also the origin of\nsolute-segregation determinants. The contribution of solutes essentially stems\nfrom their d- and s-state coupling in alloying, whereas that of matrix GB\ninterfaces is determined by matrix free surfaces. Our scheme builds a novel\npicture for the solute segregation at GBs and provides a useful tool for the\ndesign of advanced alloys."
    },
    {
        "anchor": "Calculating electron momentum densities and Compton profiles using the\n  linear tetrahedron method: A method for computing electron momentum densities and Compton profiles from\nab initio calculations is presented. Reciprocal space is divided into\noptimally-shaped tetrahedra for interpolation, and the linear tetrahedron\nmethod is used to obtain the momentum density and its projections such as\nCompton profiles. Results are presented and evaluated against experimental data\nfor Be, Cu, Ni, Fe3Pt, and YBa2Cu4O8, demonstrating the accuracy of our method\nin a wide variety of crystal structures.",
        "positive": "Simulation of X-ray diffraction in Mn$_x$Bi$_2$Te$_{3+x}$ epitaxic films: Disordered heterostructures stand as a general description for compounds that\nare part of homologous series such as bismuth chalcogenides. In device\nengineering, van der Waals epitaxy of these compounds is very promising for\napplications in spintronic and quantum computing. Structural analysis methods\nare essential to control and improve their synthesis in the form of thin films.\nRecently, X-rays tools have been proposed for structural modeling of disordered\nheterostructures [arXiv:2107.12280]. Here, we further evaluate the use of these\ntools to study the compound Mn$_x$Bi$_2$Te$_{3+x}$ in the grazing incidence\nregion of the reflectivity curves, as well as the effect of thickness\nfluctuation in the wide angle region."
    },
    {
        "anchor": "Low temperature field-effect in crystalline organic material: Molecular organic materials offer the promise of novel electronic devices but\nalso present challenges for understanding charge transport in narrow band\nsystems. Low temperature studies elucidate fundamental transport processes. We\nreport the lowest temperature field effect transport results on a crystalline\noligomeric organic material, rubrene. We find field effect switching with\non-off ratio up to 10^7 at temperatures down to 10 K. Gated transport shows a\nfactor of ~10 suppression of the thermal activation energy in 10-50 K range and\nnearly temperature independent resistivity below 10 K.",
        "positive": "Ultrafast optical manipulation of atomic arrangements in chalcogenide\n  alloy memory materials: A class of chalcogenide alloy materials that shows significant changes in\noptical properties upon an amorphous-to-crystalline phase transition has lead\nto development of large data capacities in modern optical data storage. Among\nchalcogenide phase-change materials, Ge2Sb2Te5 (GST) is most widely used\nbecause of its reliability. We use a pair of femtosecond light pulses to\ndemonstrate the ultrafast optical manipulation of atomic arrangements from\ntetrahedral (amorphous) to octahedral (crystalline) Ge-coordination in GST\nsuperlattices. Depending on the parameters of the second pump-pulse, ultrafast\nnonthermal phase-change occurred within only few-cycles (~ 1 ps) of the\ncoherent motion corresponding to a GeTe4 local vibration. Using the ultrafast\nswitch in chalcogenide alloy memory could lead to a major paradigm shift in\nmemory devices beyond the current generation of silicon-based flash-memory."
    },
    {
        "anchor": "Persistent photovoltage in methylammonium lead iodide perovskite solar\n  cells: Open circuit voltage decay measurements are performed on methylammonium lead\niodide (CH3NH3PbI3) perovskite solar cells to investigate the charge carrier\nrecombination dynamics. The measurements are compared to the two reference\npolymer-fullerene bulk heterojunction solar cells based on P3HT:PC60BM and\nPTB7:PC70BM blends. In the perovskite devices, two very different time domains\nof the voltage decay are found, with a first drop on a short time scale that is\nsimilar to the organic solar cells. However, two major differences are also\nobserved. 65-70% of the maximum photovoltage persists on much longer\ntimescales, and the recombination dynamics are dependent on the illumination\nintensity.",
        "positive": "Dirac fermion and superconductivity in two-dimensional transition-metal\n  MOH (M= Zr, Hf ): Discovery of the new two-dimensional (2D) Dirac semimetals incorporating both\nsuperconductivity and the topological band structure has provided a novel\nplatform for realizing the intriguing applications of Dirac fermions and\nMajorana quasiparticles, ranging from high-speed quantum devices at the\nnanoscale to topological quantum computations. In this work, utilizing\nfirst-principles calculations and symmetry analysis, we introduce MOH (M= Zr,\nHf) as a new topological superconductor with Dirac points close to a Fermi\nlevel which are connected with nearly flat edge states as a striking feature of\ntopological semimetals. Our calculations show that ZrOH as a 2D topological\nsemimetal can exhibit superconductivity and is a novel platform for studying\nthe interplay between superconductivity and Dirac states in low-dimensional\nmaterials."
    },
    {
        "anchor": "Resonant Spin-Dependent Tunneling in Spin-Valve Junctions in the\n  Presence of Paramagnetic Impurities: The tunnel magnetoresistance (TMR) of F/O/F magnetic junctions, (F's are\nferromagnetic layers and O is an oxide spacer) in the presence of magnetic\nimpurities within the barrier, is investigated. We assume that magnetic\ncouplings exist both between the spin of impurity and the bulk magnetization of\nthe neighboring magnetic electrode, and between the spin of impurity and the\nspin of tunneling electron. Consequently, the resonance levels of the system\nformed by a tunneling electron and a paramagnetic impurity with spin S=1, are a\nsextet. As a result the resonant tunneling depends on the direction of the\ntunneling electron spin. At low temperatures and zero bias voltage the TMR of\nthe considered system may be larger than TMR of the same structure without\nparamagnetic impurities. It is calculated that an increase in temperature leads\nto a decrease in the TMR amplitude due to excitation of spin-flip processes\nresulting in mixing of spin up and down channels. It is also shown that\nasymmetry in the location of the impurities within the barrier can lead to\nasymmetry in $I(V)$ characteristics of impurity assisted current and two\nmechanisms responsible for the origin of this effect are established. The first\none is due to the excitation of spin-flip processes at low voltages and the\nsecond one arises from the shift of resonant levels inside the insulator layer\nunder high applied voltages.",
        "positive": "Time-resolved imaging of pulse-induced magnetization reversal with a\n  microwave assist field: The reversal of the magnetization under the influence of a field pulse has\nbeen previously predicted to be an incoherent process with several competing\nphenomena such as domain wall relaxation, spin wave-mediated instability\nregions, and vortex-core mediated reversal dynamics. However, there has been no\nstudy on the direct observation of the switching process with the aid of a\nmicrowave signal input. We report a time-resolved imaging study of\nmagnetization reversal in patterned magnetic structures under the influence of\na field pulse with microwave assistance. The microwave frequency is varied to\ndemonstrate the effect of resonant microwave-assisted switching. We observe\nthat the switching process is dominated by spin wave dynamics generated as a\nresult of magnetic instabilities in the structures, and identify the\nfrequencies that are most dominant in magnetization reversal."
    },
    {
        "anchor": "The Overlapping Muffin-Tin Approximation: We present the formalism and demonstrate the use of the overlapping\nmuffin-tin approximation (OMTA). This fits a full potential to a superposition\nof spherically symmetric short-ranged potential wells plus a constant. For\none-electron potentials of this form, the standard multiple-scattering methods\ncan solve Schr\\\"{o}dingers' equation correctly to 1st order in the potential\noverlap. Choosing an augmented-plane-wave method as the source of the full\npotential, we illustrate the procedure for diamond-structured Si. First, we\ncompare the potential in the Si-centered OMTA with the full potential, and then\ncompare the corresponding OMTA $N$-th order muffin-tin orbital and\nfull-potential LAPW band structures. We find that the two latter agree\nqualitatively for a wide range of overlaps and that the valence bands have an\nrms deviation of 20 meV/electron for 30% radial overlap. Smaller overlaps give\nworse potentials and larger overlaps give larger 2nd-order errors of the\nmultiple-scattering method. To further remove the mean error of the bands for\nsmall overlaps is simple.",
        "positive": "The dielectric constant of Na_{0.4}K_{0.6}Br and its large temperature\n  variation: Since polycrystals of alkali halides are highly useful as components in\noptical devices, a number of mixed crystals of NaBr and KBr have been prepared\nfrom melt by other workers. Among these crystals, it was reported that the\npolycrystal Na$_{0.4}$K$_{0.6}$Br exhibits the strongest temperature variation\nof the dielectric constant. Here, we show quantitatively that this is due to\nthe temperature variation of the ionic polarizability."
    },
    {
        "anchor": "Asymmetrical contact scaling and measurements in MoS2 FETs: Two-dimensional (2D) materials have great potential for use in future\nelectronics due to their atomically thin nature which withstands short channel\neffects and thus enables better scalability. Device scaling is the process of\nreducing all device dimensions to achieve higher device density in a certain\nchip area. For 2D materials-based transistors, both the channel and contact\nscalability must be investigated. The channel scalability of 2D materials has\nbeen thoroughly investigated, confirming their resilience to short-channel\neffects. However, systematic studies on contact scalability remain rare and the\ncurrent understanding of contact scaling in 2D FET is inconsistent and\noversimplified. Here we combine physically scaled contacts and asymmetrical\ncontact measurements to investigate the contact scaling behavior in 2D\nfield-effect transistors (FETs). The asymmetrical contact measurements directly\ncompare electron injection with different contact lengths while using the exact\nsame channel, eliminating channel-to-channel variations. Compared to devices\nwith long contact lengths, devices with short contact lengths (scaled contacts)\nexhibit larger variation, smaller drain currents at high drain-source voltages,\nand a higher chance of showing early saturation and negative differential\nresistance. Quantum transport simulations show that the transfer length of\nNi-MoS2 contacts can be as short as 5 nm. Our results suggest that charge\ninjection at the source contact is different from injection at the drain side:\nscaled source contacts can limit the drain current, whereas scaled drain\ncontacts cannot. Furthermore, we clearly identified that the transfer length\ndepends on the quality of the metal-2D interface. The asymmetrical contact\nmeasurements proposed here will enable further understanding of contact scaling\nbehavior at various interfaces.",
        "positive": "On the nature of surface roughness with application to contact\n  mechanics, sealing, rubber friction and adhesion: Surface roughness has a huge impact on many important phenomena. The most\nimportant property of rough surfaces is the surface roughness power spectrum\nC(q). We present surface roughness power spectra of many surfaces of practical\nimportance, obtained from the surface height profile measured using optical\nmethods and the Atomic Force Microscope. We show how the power spectrum\ndetermines the contact area between two solids. We also present applications to\nsealing, rubber friction and adhesion for rough surfaces, where the power\nspectrum enters as an important input."
    },
    {
        "anchor": "Ab initio calculations of BaTiO3 and PbTiO3 (001) and (011) surface\n  structure: We present and discuss the results of calculations of surface relaxations and\nrumplings for the (001) and (011) surfaces of BaTiO3 and PbTiO3, using a hybrid\nB3PW description of exchange and correlation. On the (001) surfaces, we\nconsider both AO (A = Ba or Pb) and TiO2 terminations. In the former case, the\nsurface AO layer is found to relax inward for both materials, while outward\nrelaxations of all atoms in the second layer are found at both kinds of (001)\nterminations and for both materials. The surface relaxation energies of BaO and\nTiO2 terminations on BaTiO3 (001) are found to be comparable, as are those of\nPbO and TiO2 on PbTiO3 (001), although in both cases the relaxation energy is\nslightly larger for the TiO2 termination. As for the (011) surfaces, we\nconsider three types of surfaces, terminating on a TiO layer, a Ba or Pb layer,\nor an O layer. Here, the relaxation energies are much larger for the\nTiO-terminated than for the Ba or Pb-terminated surfaces. The relaxed surface\nenergy for the O-terminated surface is about the same as the corresponding\naverage of the TiO and Pb-terminated surfaces on PbTiO3, but much less than the\naverage of the TiO and Ba-terminated surfaces on BaTiO3. We predict a\nconsiderable increase of the Ti-O chemical bond covalency near the BaTiO3 and\nPbTiO3 (011) surface as compared to both the bulk and the (001) surface.",
        "positive": "Electron vortices in crystals: The propagation of electron beams carrying angular momentum in crystals is\nstudied using a multislice approach for the model system Fe. It is found that\nthe vortex beam is distorted strongly due to elastic scattering. Consequently,\nthe expectation value of the angular momentum as well as the local vortex\ncomponents change with the initial position of the vortex and the propagation\ndepth, making numerical simulations indispensable when analyzing experiments."
    },
    {
        "anchor": "Electronic structure, hyperfine interactions and disordering effects in\n  iron nitride Fe4N: Iron nitride Fe4N is studied by full-potential LAPW method. Structure\nparameters, electronic and magnetic properties as well as hyperfine interaction\nparameters are obtained. We observe perfect agreement with experimental\nresults. Hypothetical Fe4N structure was also calculated to study the influence\nof disordering effects on parameters of Moessbauer spectra. We performed\ndetailed analysis of EFG formation on Fe nuclei including magnetization\neffects. We show that the formation of N-Fe-N local configuration is\nenergetically favourable in nitrogen austenites.",
        "positive": "Theoretical Studies of Quantum Interference in Electronic Transport\n  Through Carbon Nanotubes: We performed studies of coherent electronic transport through a single walled\ncarbon nanotube. In the calculations multiple scattering on the contacts and\ninterference processes were taken into account. Conductance is a composition of\ncontributions from different channels. We studied also spin--dependent\ntransport in the system with ferromagnetic electrodes.\n  The magnetoresistance is large and shows large oscillations, it can be even\nnegative in some cases."
    },
    {
        "anchor": "Optical conductivity from local anharmonic phonons: Recently there has been paid much attention to phenomena caused by local\nanharmonic vibrations of the guest ions encapsulated in polyhedral cages of\nmaterials such as pyrochlore oxides, filled skutterdites and clathrates. We\ntheoretically investigate the optical conductivity solely due to these\nso-called rattling phonons in a one-dimensional anharmonic potential model. The\ndipole interaction of the guest ions with electric fields induces excitations\nexpressed as transitions among vibrational states with non-equally spaced\nenergies, resulting in a natural line broadening and a shift of the peak\nfrequency as anharmonic effects. In the case of a single well potential, a\nsoftening of the peak frequency and an asymmetric narrowing of the line width\nwith decreasing temperature are understood as a shift of the spectral weight to\nlower level transitions. On the other hand, the case of a double minima\npotential leads to a multi-splitting of a spectral peak in the conductivity\nspectrum with decreasing temperature.",
        "positive": "Comparison of exact-exchange calculations for solids in\n  current-spin-density- and spin-density-functional theory: The relative merits of current-spin-density- and spin-density-functional\ntheory are investigated for solids treated within the exact-exchange-only\napproximation. Spin-orbit splittings and orbital magnetic moments are\ndetermined at zero external magnetic field. We find that for magnetic (Fe, Co\nand Ni) and non-magnetic (Si and Ge) solids, the exact-exchange\ncurrent-spin-density functional approach does not significantly improve the\naccuracy of the corresponding spin-density functional results."
    },
    {
        "anchor": "Diffusivity and derivatives for interstitial solutes: Activation energy,\n  volume, and elastodiffusion tensors: Computational atomic-scale methods continue to provide new information about\ngeometry, energetics, and transition states for interstitial elements in\ncrystalline lattices. This data can be used to determine the diffusivity of\ninterstitials by finding steady-state solutions to the master equation. In\naddition, atomic-scale computations can provide not just the site energy, but\nalso the stress in the cell due to the introduction of the defect to compute\nthe elastic dipole. We derive a general expression for the fully anistropic\ndiffusivity tensor from site and transition state energies, and three\nderivatives of the diffusivity: the elastodiffusion tensor (derivative of\ndiffusivity with respect to strain), the activation barrier tensor (logarithmic\nderivative of diffusivity with respect to inverse temperature) and activation\nvolume tensor (logarithmic derivative of diffusivity with respect to pressure).\nComputation of these quantities takes advantage of crystalline symmetry, and we\nprovide an open-source implementation of the algorithm. We provide analytic\nresults for octahedral-tetrahedral networks in face-centered cubic,\nbody-centered cubic, and hexagonal closed-packed lattices, and conclude with\nnumerical results for C in Fe.",
        "positive": "First-principles study of the incorporation and diffusion of helium in\n  cubic zirconia: The incorporation and diffusion of helium (He) with and without intrinsic\nvacancy defects in cubic ZrO$_{2}$ are investigated through first-principles\ntotal-energy calculations, in which the projector-augmented-wave (PAW) method\nwith the generalized gradient approximation (GGA) is used. The calculated\nformation energies of intrinsic point defects indicate that cubic ZrO$_{2}$ has\na tolerant resistance to radiation damage. The incorporation energy of He\nimpurity shows that it is preferable to occupy the Zr vacancy at first, whereas\nthe solution energy suggests that He would be accommodated in the interstitial\nsite at thermodynamic equilibrium concentration. By calculating the He\nmigration energies corresponding to both interstitial and vacancy assisted\nmechanisms, we suggest that it is most likely for He to diffuse by hopping\nthrough a single vacancy. Remarkably, our calculated vacancy-assisted diffusion\nenergy of He is consistent well with the experimental measurement."
    },
    {
        "anchor": "Phonon limited thermoelectric transport in Pb: We present a fully ab initio based scheme to compute transport properties,\ni.e. the electrical conductivity {\\sigma} and thermopower S, in the presence of\nelectron-phonon interaction. Therefore, we explicitly investigate the\nk-dependent structure of the Eliashberg spectral function , the coupling\nstrength, the linewidth and the relaxation time {\\tau}. We obtain a\nstate-dependent {\\tau} and show its necessity to reproduce the increased\nthermopower at temperatures below the Debye temperature, without accounting for\nthe phonon-drag effect. Despite the detailed investigations of various k and q\ndependencies, the presented scheme can be easily applied to more complicated\nsystems.",
        "positive": "On non-singular crack fields in Helmholtz type enriched elasticity\n  theories: Recently, simple non-singular stress fields of cracks of mode I and mode III\nhave been published by Aifantis (2009,2012), Isaksson and H\\\"agglund (2013) and\nIsaksson et al. (2012). In this work we investigate the physical meaning and\ninterpretation of those solutions and if they satisfy important physical\nconditions (equilibrium, boundary and compatibility conditions)."
    },
    {
        "anchor": "Hydrogen permeation on defected \u03b1-Al2O3 surfaces: DFT\n  calculations: One of the key challenges to realize controlled fusion energy is tritium\nself-sufficiency. The application of hydrogen permeation barrier (HPB) is\nconsidered to be necessary for tritium self-sufficiency. {\\alpha}-Al2O3 is\ncurrently a candidate material for HPB. However, a crucial issue for\n{\\alpha}-Al2O3 is that its permeability reduction factor (PRF) will\ndramatically drop after ion or neutron irradiations. At present, little is\nknown about the relevant mechanism. In order to shed light on this issue, the\nkinetics and energetic changes of hydrogen on defected {\\alpha}-Al2O3 surfaces\nin comparison with perfect {\\alpha}-Al2O3 surfaces were studied by density\nfunctional theory. For perfect {\\alpha}-Al2O3 surfaces, the results show that\nthe barrier for hydrogen migration from the outermost layer into the subsurface\nlayer is the highest, making this migration step to be a rate limiting process.\nIn contrast, surface point defects dramatically reduce this maximum barrier.\nConsequently, hydrogen can preferentially permeate into the interior of the\nmaterial through surface defects. The findings can help explain the possible\nmechanism of significant decrease of PRF under radiation.",
        "positive": "Assessment of a nonempirical semilocal density functional on solids and\n  surfaces: Recently, Tao and Mo developed a new nonempirical semilocal\nexchange-correlation density functional. The exchange part of this functional\nis derived from a density matrix expansion corrected to reproduce the\nfourth-order gradient expansion in the slowly varying limit, while the\ncorrelation part is based on the TPSS correlation model with a modification for\nthe low-density limit. In the present work, the Tao-Mo functional is assessed\nby calculations on a variety of solids and jellium surfaces. This includes 22\nlattice constants and bulk moduli, 7 cohesive energies, and jellium surface\nexchange and correlation energies for the density parameter rs in the range\nfrom 2 to 3 bohrs. Our calculations show that this meta-generalized gradient\napproximation can yield consistently remarkable accuracy for the properties\nconsidered here, with mean absolute errors of 0.017 {\\AA} for lattice\nconstants, 7.0 GPa for bulk moduli, 0.08 eV for cohesive energies, and 35\nerg/cm2 for surface exchange-correlation energies, substantially improving upon\nexisting nonempirical semilocal density functionals."
    },
    {
        "anchor": "First step towards a Devil's Staircase in Spin Crossover materials First\n  step towards Devil's Staircase in Spin Crossover materials: The devil is in the detail: Periodic and aperiodic spin-state concentration\nwaves form during \"Devil's staircase\"-type spincrossover in a new bimetallic 2D\ncoordination polymer {Fe[(Hg(SCN)3)2](4,4'-bipy)2}n.The unprecedented\nbimetallic 2D coordination polymer {Fe[(Hg(SCN)3)2](4,4'-bipy)2}n exhibits a\nthermal high-spin (HS)$low-spin (LS) staircase-like conversion characterized by\na multi-step dependence of the HS molar fraction gHS. Between the fully HS\n(gHS=1) and LS (gHS=0) phases, two steps associated with different ordering\nappear in terms of spin-state concentration waves (SSCW). On the gHS=0.5 step,\na periodic SSCW forms with a HS-LS-HS-LS sequence. On the gHS=0.34 step, the 4D\nsuperspace crystallography structural refinement reveals an aperiodic SSCW,\nwith a HS-LS sequence incommensurate with the molecular lattice. The formation\nof these different long-range spatially ordered structures of LS and HS states\nduring the multi-step spin-crossover is discussed within the framework of\n\"Devil's staircase\"-type transitions. Spatially modulated phases are known in\nvarious types of materials but are uniquely related to molecular HS/LS\nbistability in this case.",
        "positive": "Terahertz detection based on nonlinear Hall effect without magnetic\n  field: We propose a method for broadband long-wavelength photodetection using the\nnonlinear Hall effect in non-centrosymmetric quantum materials. The inherently\nquadratic relation between transverse current and input voltage at zero\nmagnetic field is used to rectify the incident terahertz or infrared electric\nfield into a direct current, without invoking any diode. Our photodetector\noperates at zero external bias with fast response speed and has zero threshold\nvoltage. Remarkably, the intrinsic current responsivity due to Berry curvature\nmechanism is a material property independent of the incident frequency or the\nscattering rate, which can be evaluated from first-principles electronic\nstructure calculations. We identify the Weyl semimetal NbP for terahertz\nphotodection with large current responsivity reaching $\\sim 1$A/W without\nexternal bias."
    },
    {
        "anchor": "Interface enhanced spin-orbit torques and current-induced magnetization\n  switching of Pd/Co/AlO$_x$ layers: Magnetic heterostructures that combine large spin-orbit torque efficiency,\nperpendicular magnetic anisotropy, and low resistivity are key to develop\nelectrically-controlled memory and logic devices. Here we report on vector\nmeasurements of the current-induced spin orbit torques and magnetization\nswitching in perpendicularly magnetized Pd/Co/AlO$_x$ layers as a function of\nPd thickness. We find sizeable damping-like (DL) and field-like (FL) torques,\nof the order of 1~mT per $10^7$~A/cm$^2$, which have different thickness and\nmagnetization angle dependence. The analysis of the DL torque efficiency per\nunit current density and electric field using drift-diffusion theory leads to\nan effective spin Hall angle and spin diffusion length of Pd larger than 0.03\nand 7~nm, respectively. The FL SOT includes a significant interface\ncontribution, is larger than estimated using drift-diffusion parameters, and is\nfurther strongly enhanced upon rotation of the magnetization from the\nout-of-plane to the in-plane direction. Finally, taking advantage of the large\nspin-orbit torques in this system, we demonstrate bipolar magnetization\nswitching of Pd/Co/AlO$_x$ layers with similar current density as used for\nPt/Co layers with comparable perpendicular magnetic anisotropy.",
        "positive": "Anharmonic Phonon Quasiparticle Theory of Zero-point and Thermal Shifts\n  in Insulators: Heat Capacity, Bulk Modulus, and Thermal Expansion: The Quasi-harmonic (QH) approximation uses harmonic vibrational frequencies\nomega(H,Q,V), computed at volumes V near the volume where the Born-Oppenheimer\n(BO) energy is minimum. When this is used in the harmonic free energy, QH\napproximation gives a good zeroth order theory of thermal expansion, and first\norder theory of bulk modulus. Here, n-th order means smaller than the leading\nterm by n powers of epsilon, where epsilon is the ratio hbar omega(Q)/E(el) or\nkT/E(el), and E(el) is an electronic energy scale, typically 2 to 10 eV.\nExperiment often shows evidence for next order corrections. When such\ncorrections are needed, anharmonic interactions must be included. The most\naccessible measure of anhamonicity is the quasiparticle (QP) energy,\nomega(Q,V,T), seen experimentally by vibrational spectroscopy. However, this\ncannot just be inserted into the harmonic free energy F(H). In this paper, a\nfree energy formula is found which corrects the double-counting of anharmonic\ninteractions that is made when F is approximated by F(H,omega(Q,V,T)). The term\n\"QP thermodynamics\" is used for this way of treating anharmonicity. It enables\n(n+1)-order corrections, if QH theory is accurate to order n. This procedure is\nused to give corrections to specific heat and volume thermal expansion. The QH\nformulas for isothermal and adiabatic bulk moduli are clarified, and the route\nto higher order corrections is indicated."
    },
    {
        "anchor": "Coherent propagation and incoherent diffusion of elastic waves in a two\n  dimensional continuum with a random distribution of edge dislocations: We study the coherent propagation and incoherent diffusion of in-plane\nelastic waves in a two dimensional continuum populated by many, randomly placed\nand oriented, edge dislocations. Because of the Peierls-Nabarro force the\ndislocations can oscillate around an equilibrium position with frequency\n$\\omega_0$. The coupling between waves and dislocations is given by the\nPeach-Koehler force. This leads to a wave equation with an inhomogeneous term\nthat involves a differential operator. In the coherent case, a Dyson equation\nfor a mass operator is set up and solved to all orders in perturbation theory\nin independent scattering approximation (ISA). As a result, a complex index of\nrefraction is obtained, from which an effectve wave velocity and attenuation\ncan be read off, for both longitudinal and transverse waves. In the incoherent\ncase a Bethe-Salpeter equation is set up, and solved to leading order in\nperturbation theory in the limit of low frequency and wave number. A diffusion\nequation is obtained and the (frequency-dependent) diffusion coefficient is\nexplicitly calculated. It reduces to the value obtained with energy transfer\narguments at low frequency. An important intermediate step is the obtention of\na Ward-Takahashi identity (WTI) for a wave equation that involves a\ndifferential operator, which is shown to be compatible with the ISA.",
        "positive": "Hole compensation effect in III-Mn-V dilute ferromagnetic semiconductors: A systematic study of hole compensation effect on magnetic properties, which\nis controlled by defect compensation through ion irradiation, in (Ga,Mn)As,\n(In,Mn)As and (Ga,Mn)P is presented in this work. In all materials, both Curie\ntemperature and magnetization decrease upon increasing the hole compensation,\nconfirming the description of hole mediated ferromagnetism according to the p-d\nZener model. The material dependence of Curie temperature and magnetization\nversus hole compensation reveals that the manipulation of magnetic properties\nin III-Mn-V dilute ferromagnetic semiconductors by ion irradiation is strongly\ninfluenced by the energy level location of the produced defect relative to the\nband edges in semiconductors."
    },
    {
        "anchor": "Complementary ab initio and X-ray nano-diffraction study of Ta2O5: Numerous different crystal structures of Ta2O5 are reported in literature.\nAlthough experimentally and computationally obtained lattice parameters and\nmechanical properties are in excellent agreement there is a pronounced\ndeviation when it comes to electronic structures of Ta2O5. Based on ab initio\nstudies and nano-beam X-ray diffraction of sputtered Ta2O5 thin films, we\nintroduce an orthorhombic basic structure with a = 0.6425, b = 0.3769, and c =\n0.7706 nm, which is stabilized by flipping of an oxygen atom in neighboring\nc-planes. The calculated energy of formation is with -3.209 eV/atom almost as\nlow as -3.259 eV/atom for the well-known Stephenson superstructure. We propose\nthe new structure based on the fact that it allows for a good description of\northorhombic Ta2O5 even with a small and simple unit cell, which is especially\nadvantageous for computational studies.",
        "positive": "Metalorganic Chemical Vapor Deposition of \\b{eta}-(AlxGa1-x)2O3 thin\n  films on (001) \\b{eta}-Ga2O3 substrates: Phase pure \\b{eta}-(AlxGa1-x)2O3 thin films are grown on (001) oriented\n\\b{eta}-Ga2O3 substrates via metalorganic chemical vapor deposition (MOCVD). By\nsystematically tuning the precursor molar flow rates, the epitaxial growth of\ncoherently strained \\b{eta}-(AlxGa1-x)2O3 films are demonstrated with up to 25%\nAl compositions as evaluated by high resolution x-ray diffraction (XRD). The\nasymmetrical reciprocal space mapping confirms the growth of coherent\n\\b{eta}-(AlxGa1-x)2O3 films (x < 25%) on (001) \\b{eta}-Ga2O3 substrates. While\nthe films show smooth surface morphologies, the alloy inhomogeneity with local\nsegregation of Al along (-201) plane is observed from atomic resolution STEM\nimaging, resulting in wavy and inhomogeneous interfaces in\n\\b{eta}-(AlxGa1-x)2O3/\\b{eta}-Ga2O3 superlattice structure. Room temperature\nRaman spectra of \\b{eta}-(AlxGa1-x)2O3 films show similar characteristics peaks\nas (001) \\b{eta}-Ga2O3 substrate without obvious Raman shifts for films with\ndifferent Al compositions. Atom probe tomography (APT) was used to investigate\nthe atomic level structural chemistry with increasing Al content in the\n\\b{eta}-(AlxGa1-x)2O3 films. A monotonous increase in chemical heterogeneity is\nobserved from the in-plane Al/Ga distributions which was further confirmed via\nstatistical frequency distribution analysis (FDA). Although the films exhibit\nalloy fluctuations, n-type doping with good electrical properties are\ndemonstrated for films with various Al compositions. The determined valence and\nconduction band offsets at \\b{eta}-(AlxGa1-x)2O3/\\b{eta}-Ga2O3 heterojunctions\nusing x-ray photoelectron spectroscopy (XPS) reveal the formation of type-II\n(staggered) band alignment."
    },
    {
        "anchor": "Mechanical Response of Mesoporous Amorphous NiTi Alloy to External\n  Deformations: The porous titanium nickelide is very popular in various industries due to\nunique combination of physical and mechanical properties such as shape memory\neffect, high corrosion resistance, and biocompatibility. The non-equilibrium\nmolecular dynamics simulation was applied to study the influence of porosity\ndegree on mechanical properties of porous amorphous titanium nickelide at\nuniaxial tension, uniaxial compression, and uniform shear. We have found that\nthe porous amorphous alloy is characterized by a relatively large value of\nYoung's modulus in comparison to its crystalline analogue. It has been found\nthat the system with a percolated network of pores exhibits improved elastic\ncharacteristics associated with resistance to tensile and shear. The system\ncontained isolated spherical pores is more resistant to compression and less\nresistant to tensile and shear. These results can be applied to develop and\nimprove the methods for making amorphous metal foams.",
        "positive": "Quantum Transport Calculations Using Periodic Boundary Conditions: An efficient new method is presented to calculate the quantum transports\nusing periodic boundary conditions. This method allows the use of conventional\nground state ab initio programs without big changes. The computational effort\nis only a few times of a normal ground state calculation, thus it makes\naccurate quantum transport calculations for large systems possible."
    },
    {
        "anchor": "A quasi-conserved particle Monte Carlo model of surface evolution with\n  semi-empirical sputter yield modulated erosion: 1 keV Ar$^+$ sputtering of Si: We introduce a new Monte Carlo model based on a semi-empirical sputter yield\nparameter in ion-solid energetic collisions. This model circumvents the\ncomplexity of the existing statistical, classical and continuum models, most of\nwhich are difficult to relate to real experimental parameters, by its\nsemi-empirical nature of direct reliance on the experimental values of the\nsputter yield. Constrained by this crucial experimental factor, the model then\naddresses the multidimensional nature of other accompanying physical processes\nstochastically; thus reducing the complexity of their computation. This model\nexhibits the experimentally observed features of solid surfaces that evolve\nunder continuous particle irradiation and allows for a way to study the effect\nof the different mechanisms of the surface morphology and the nature of their\ninterplay in the dynamics of the surface evolution. Our study of the average\nsurface height reveals that it is constant when eroded particles are\nredeposited but varies linearly with simulation time, when eroded particles are\nnot redeposited. Our studies also show that the roughening process is not\nsignificantly affected by re-deposition of eroded material.",
        "positive": "Half-Metallic Silicon Nanowires: Multiple Surface Dangling Bonds and\n  Nonmagnetic Doping: By means of first-principles density functional theory calculations, we find\nthat hydrogen-passivated ultrathin silicon nanowires (SiNWs) along [100]\ndirection with symmetrical multiple surface dangling bonds (SDBs) and boron\ndoping can have a half-metallic ground state with 100% spin polarization, where\nthe half-metallicity is shown quite robust against external electric fields.\nUnder the circumstances with various SDBs, the H-passivated SiNWs can also be\nferromagnetic or antiferromagnetic semiconductors. The present study not only\noffers a possible route to engineer half-metallic SiNWs without containing\nmagnetic atoms but also sheds light on manipulating spin-dependent properties\nof nanowires through surface passivation."
    },
    {
        "anchor": "Relaxation of Terrace-width Distributions: Physical Information from\n  Fokker-Planck Time: Recently some of us have constructed a Fokker-Planck formalism to describe\nthe equilibration of the terrace-width distribution of a vicinal surface from\nan arbitrary initial configuration. However, the meaning of the associated\nrelaxation time, related to the strength of the random noise in the underlying\nLangevin equation, was rather unclear. Here we present a set of careful kinetic\nMonte Carlo simulations that demonstrate convincingly that the time constant\nshows activated behavior with a barrier that has a physically plausible\ndependence on the energies of the governing microscopic model. Furthermore, the\nFokker-Planck time at least semiquantitatively tracks the actual physical time.",
        "positive": "Structural and Electronic Properties of Graphene and Graphene-like\n  Materials: Using full potential density functional theory calculations we have\ninvestigated the structural and electronic properties of graphene and some\nother graphene-like materials, viz., monolayer of SiC, GeC, BN, AlN, GaN, ZnO,\nZnS and ZnSe. We hope, with the advancement of material synthesis techniques,\nsome these new materials will be synthesized in the near future for potential\napplications in various nano-devices."
    },
    {
        "anchor": "Unveiling multiferroic proximity effect in graphene: We demonstrate that electronic and magnetic properties of graphene can be\ntuned via proximity of multiferroic substrate. Our first-principles\ncalculations performed both with and without spin-orbit coupling clearly show\nthat by contacting graphene with bismuth ferrite BiFeO$_3$ (BFO) film, the\nspin-dependent electronic structure of graphene is strongly impacted both by\nthe magnetic order and by electric polarization in the underlying BFO. Based on\nextracted Hamiltonian parameters obtained from the graphene band structure, we\npropose a concept of six-resistance device based on exploring multiferroic\nproximity effect giving rise to significant proximity electro- (PER), magneto-\n(PMR), and multiferroic (PMER) resistance effects. This finding paves a way\ntowards multiferroic control of magnetic properties in two dimensional\nmaterials.",
        "positive": "Impact of octahedral rotations on Ruddlesden-Popper phases of\n  antiferrodistortive perovskites: This work presents the most detailed and extensive theoretical study to date\nof the structural configurations of Ruddlesden-Popper (RP) phases in\nantiferrodistortive (AFD) perovskites and formulates a program of study which\ncan be pursued for RP phases of any AFD perovskite system. We systematically\ninvestigate the effects of oxygen octahedral rotations on the energies of RP\nphases in AFD perovskites (A_n+1 B_n O_3n+1) for n = 1...30, providing\nasymptotic results for n --> infinity that give both the form of the\ninteraction between stacking faults and the behavior of such stacking faults in\nisolation. We find an inverse-distance interaction between faults with a\nstrength which varies by as much as a factor of two depending on the\nconfiguration of the octahedra. We find that the strength of this effect can be\nsufficient to (a) stabilize or destabilize the RP phase with respect to\ndissociation into the bulk perovskite and the bulk A-oxide and (b) affect the\nenergy scales of the RP phase sufficiently to constrain the rotational states\nof the octahedra neighboring the stacking faults, even at temperatures where\nthe octahedra in the bulk regions librate freely. Finally, we present evidence\nthat the importance of the octahedral rotations can be understood in terms of\nchanges in the distances between oxygen ions on opposing sides of the RP\nstacking faults."
    },
    {
        "anchor": "Direct Evidence for Multiferroic Magnetoelectric Coupling in\n  0.9BiFeO3-0.1BaTiO3: Magnetic, dielectric and calorimetric studies on 0.9BiFeO3-0.1BaTiO3 indicate\nstrong magnetoelectric coupling. XRD studies reveal a very remarkable change in\nthe rhombohedral distortion angle and a significant shift in the atomic\npositions at the magnetic Tc due to an isostructural phase transition. The\ncalculated polarization using Rietveld refined atomic positions scales linearly\nwith magnetization. Our results provide the first unambiguous evidence for\nmagnetoelectric coupling of intrinsic multiferroic origin in a BiFeO3 based\nsystem.",
        "positive": "Direct Wolf summation of a polarizable force field for silica: We extend the Wolf direct, pairwise r^(-1) summation method with spherical\ntruncation to dipolar interactions in silica. The Tangney-Scandolo interatomic\nforce field for silica takes regard of polarizable oxygen atoms whose dipole\nmoments are determined by iteration to a self-consistent solution. With Wolf\nsummation, the computational effort scales linearly in the system size and can\neasily be distributed among many processors, thus making large-scale\nsimulations of dipoles possible. The details of the implementation are\nexplained. The approach is validated by estimations of the error term and\nsimulations of microstructural and thermodynamic properties of silica."
    },
    {
        "anchor": "Phase separation and effect of strain on magnetic properties of\n  Mn$_3$Ga$_{1-x}$Sn$_x$C: While the unit cell volume of compounds belonging to the\nMn$_3$Ga$_{1-x}$Sn$_x$C, (0 $ \\le x \\le $ 1) series shows a conformity with\nVegard's law, their magnetic and magnetocaloric properties behave differently\nfrom those of parent compounds Mn$_3$GaC and Mn$_3$SnC. A correlation between\nthe observed magnetic properties and underlying magnetic and local structure\nsuggests that replacing Ga atoms by larger atoms of Sn results in the formation\nof Ga-rich and Sn-rich clusters. As a result, even though the long range\nstructure appears to be cubic, Mn atoms find themselves in two different local\nenvironments. The packing of these two different local structures into a single\nglobal structure induces tensile/compressive strains on the Mn$_{6}$C\nfunctional unit and is responsible for the observed magnetic properties across\nthe entire solid solution range.",
        "positive": "CEGANN: Crystal Edge Graph Attention Neural Network for multiscale\n  classification of materials environment: Machine learning models and applications in materials design and discovery\ntypically involve the use of feature representations or \"descriptors\" followed\nby a learning algorithm that maps them to a user-desired property of interest.\nMost popular mathematical formulation-based descriptors are not unique across\natomic environments or suffer from transferability issues across different\napplication domains and/or material classes. In this work, we introduce the\nCrystal Edge Graph Attention Neural Network (CEGANN) workflow that uses graph\nattention-based architecture to learn unique feature representations and\nperform classification of materials across multiple scales (from atomic to\nmesoscale) and diverse classes ranging from metals, oxides, non-metals and even\nhierarchical materials such as zeolites and semi ordered materials such as\nmesophases. We first demonstrate a case study where the classification is based\non a global, structure-level representation such as space group and structural\ndimensionality (e.g., bulk, 2D, clusters etc.). Using representative materials\nsuch as polycrystals and zeolites, we next demonstrate the transferability of\nour network in successfully performing local atom-level classification tasks,\nsuch as grain boundary identification and other heterointerfaces. We also\ndemonstrate classification in (thermal) noisy dynamical environments using a\nrepresentative example of crystal nucleation and growth of a zeolite polymorph\nfrom an amorphous synthesis mixture. Finally, we characterize the formation of\na binary mesophase and its phase transitions and the growth of ice,\ndemonstrating the performance of CEGANN in systems with thermal noise and\ncompositional diversity. Overall, our approach is agnostic to the material type\nand allows for multiscale classification of features ranging from atomic-scale\ncrystal structures to heterointerfaces to microscale grain boundaries."
    },
    {
        "anchor": "Surface activation by electron scavenger metal nanorod adsorption on\n  TiH2, TiC, TiN, and Ti2O3: Metal/oxide support perimeter sites are known to provide unique properties\nbecause the nearby metal changes the local environment on the support surface.\nIn particular, the electron scavenger effect reduces the energy necessary for\nsurface anion desorption, thereby contributes to activation of the (reverse)\nMars-van Krevelen mechanism. This study investigated the possibility of such\nactivation in hydrides, carbides, nitrides, and sulfides. The work functions\n(WFs) of known hydrides, carbides, nitrides, oxides, and sulfides with group 3,\n4, or 5 cations (Sc, Y, La, Ti, Zr, Hf, V, Nb, and Ta) were calculated. The WFs\nof most hydrides, carbides, and nitrides are smaller than the WF of Ag,\nimplying that the electron scavenger effect may occur when late transition\nmetal nanoparticles are adsorbed on the surface. The WF of oxides and sulfides\ndecrease when reduced. The surface anion vacancy formation energy correlates\nwell with the bulk formation energy in carbides and nitrides, while almost no\ncorrelation is found in hydrides because of the small range of surface hydrogen\nvacancy formation energy values. The electron scavenger effect is explicitly\nobserved in nanorods adsorbed on TiH2 and Ti2O3; the surface vacancy formation\nenergy decreases at anion sites near the nanorod, and charge transfer to the\nnanorod happens when an anion is removed at such sites. Activation of hydrides,\ncarbides, and nitrides by nanorod adsorption and screening support materials\nthrough WF calculation are expected to open up a new category of supported\ncatalysts.",
        "positive": "Phase-Space Explorations in Time-Dependent Density Functional Theory: We discuss two problems which are particularly challenging for approximations\nin time-dependent density functional theory (TDDFT) to capture:\nmomentum-distributions in ionization processes, and memory-dependence in\nreal-time dynamics. We propose an extension of TDDFT to phase-space densities,\ndiscuss some formal aspects of such a \"phase-space density functional theory\"\nand explain why it could ameliorate the problems in both cases. For each\nproblem, a two-electron model system is exactly numerically solved and analysed\nin phase-space via the Wigner function distribution."
    },
    {
        "anchor": "Momentum-space signatures of Berry flux monopoles in a Weyl semimetal: Since the early days of Dirac flux quantization, magnetic monopoles have been\nsought after as a potential corollary of quantized electric charge. As opposed\nto magnetic monopoles embedded into the theory of electromagnetism, Weyl\ncrystals exhibit Berry flux monopoles in reciprocal parameter space. As a\nfunction of crystal momentum, such monopoles locate at the degeneracy point of\nthe Weyl cone. Here, we report momentum-resolved spectroscopic signatures of\nBerry flux monopoles in TaAs as a paradigmatic Weyl semimetal. We have probed\nthe orbital and spin angular momentum (OAM and SAM) of the Weyl-fermion states\nby angle-resolved photoemission spectroscopy at bulk-sensitive soft X-ray\nenergies (SX-ARPES) combined with photoelectron spin detection and circular\ndichroism. Supported by first-principles calculations, our measurements image\ncharacteristics of a topologically non-trivial winding of the OAM at the Weyl\nnodes and unveil a chirality-dependent SAM of the Weyl bands. Our results\nexperimentally visualize the non-trivial momentum-space topology in a Weyl\nsemimetal, promising to have profound implications for the study of\nquantum-geometric effects in solids.",
        "positive": "A first-principles machine-learning force field for heterogeneous ice\n  nucleation on microcline feldspar: The formation of ice in the atmosphere affects precipitation and cloud\nproperties, and plays a key role in the climate of our planet. Although ice can\nform directly from liquid water at deeply supercooled conditions, the presence\nof foreign particles can aid ice formation at much warmer temperatures. Over\nthe past decade, experiments have highlighted the remarkable efficiency of\nfeldspar minerals as ice nuclei compared to other particles present in the\natmosphere. However, the exact mechanism of ice formation on feldspar surfaces\nhas yet to be fully understood. Here, we develop a first-principles\nmachine-learning model for the potential energy surface aimed at studying ice\nnucleation at microcline feldspar surfaces. The model is able to reproduce with\nhigh fidelity the energies and forces derived from density-functional theory\n(DFT) based on the SCAN exchange and correlation functional. We apply the\nmachine-learning force field to study different fully-hydroxylated terminations\nof the (100), (010), and (001) surfaces of microcline exposed to vacuum. Our\ncalculations suggest that terminations that do not minimize the number of\nbroken bonds are preferred in vacuum. We also study the structure of\nsupercooled liquid water in contact with microcline surfaces, and find that\nwater density correlations extend up to around 1 nm from the surfaces. Finally,\nwe show that the force field maintains a high accuracy during the simulation of\nice formation at microcline surfaces, even for large systems of around 30,000\natoms. Future work will be directed towards the calculation of nucleation free\nenergy barriers and rates using the force field developed herein, and\nunderstanding the role of different microcline surfaces on ice nucleation."
    },
    {
        "anchor": "High-Pressure Na3(N2)4, Ca3(N2)4, Sr3(N2)4, and Ba(N2)3 Featuring\n  Nitrogen Dimers with Non-Integer Charges and Anion-Driven Metallicity: Charged nitrogen dimers are ubiquitous in high-pressure binary metal-nitrogen\nsystems. They are known to possess integer formal charges x varying from one\nthrough four. Here, we present the investigation of the binary alkali- and\nalkaline earth metal-nitrogen systems, Na-N, Ca-N, Sr-N, Ba-N to 70 GPa. We\nreport on compounds-Na3(N2)4, Ca3(N2)4, Sr3(N2)4, and Ba(N2)3-featuring charged\nnitrogen dimers with paradigm-breaking non-integer charges, x = 0.67, 0.75 and\n1.5. The metallic nature of all four compounds is deduced from ab initio\ncalculations. The conduction electrons occupy the pi* antibonding orbitals of\nthe charged nitrogen dimers that results in anion-driven metallicity.\nDelocalization of these electrons over the pi* antibonding states enables the\nnon-integer electron count of the dinitrogen species. Anion-driven metallicity\nis expected to be found among a variety of compounds with homoatomic anions\n(e.g., polynitrides, carbides, and oxides), with the conduction electrons\nplaying a decisive role in their properties.",
        "positive": "First-Principles Prediction of Graphene-Like XBi (X=Si, Ge, Sn)\n  Nanosheets: Research progress on single-layer group III monochalcogenides have been\nincreasing rapidly owing to their interesting physics. Herein, we predict the\ndynamically stable single-layer forms of XBi (X=Ge, Si, or Sn) by using density\nfunctional theory calculations. Phonon band dispersion calculations and\nab-initio molecular dynamics simulations reveal the dynamical and thermal\nstability of predicted nanosheets. Raman spectra calculations indicate the\nexistence of 5 Raman active phonon modes 3 of which are prominent and can be\nobserved in a possible Raman measurement. Electronic band structures of the XBi\nsingle-layers investigated with and without spin-orbit coupling effects (SOC).\nOur results show that XBi single-layers show semiconducting property with the\nnarrow band gap values without SOC. However only the single-layer SiBi is an\nindirect band gap semiconductor while GeBi and SnBi exhibit metallic behaviors\nby adding spin-orbit coupling effects. In addition, the calculated\nlinear-elastic parameters indicate the soft nature of predicted monolayers.\nMoreover, our predictions for the thermoelectric properties of single-layer XBi\nreveal that SiBi is a good thermoelectric material with increasing temperature.\nOverall, it is proposed that single-layer XBi structures can be alternative,\nstable 2D single-layers with their varying electronic and thermoelectric\nproperties."
    },
    {
        "anchor": "Magnetic Exchange Couplings from Noncollinear Spin Density Functional\n  Perturbation Theory: We propose a method for the evaluation of magnetic exchange couplings based\non noncollinear spin-density functional calculations. The method employs the\nsecond derivative of the total Kohn-Sham energy of a single reference state, in\ncontrast to approximations based on Kohn-Sham total energy differences. The\nadvantage of our approach is twofold: It provides a physically motivated\npicture of the transition from a low-spin to a high-spin state, and it utilizes\na perturbation scheme for the evaluation of magnetic exchange couplings. The\nlatter simplifies the way these parameters are predicted using\nfirst-principles: It avoids the non-trivial search for different spin-states\nthat needs to be carried out in energy difference methods and it opens the\npossibility of \"black-boxifying\" the extraction of exchange couplings from\ndensity functional theory calculations. We present proof of concept\ncalculations of magnetic exchange couplings in the H--He--H model system and in\nan oxovanadium bimetallic complex where the results can be intuitively\nrationalized.",
        "positive": "Ferromagnetic resonance with magnetic phase selectivity by means of\n  resonant elastic x-ray scattering on a chiral magnet: Cubic chiral magnets, such as Cu$_{2}$OSeO$_{3}$, exhibit a variety of\nnon-collinear spin textures, including a trigonal lattice of spin whirls,\nso-called skyrmions. Using magnetic resonant elastic x-ray scattering (REXS) on\na crystalline Bragg peak and its magnetic satellites while exciting the sample\nwith magnetic fields at GHz frequencies, we probe the ferromagnetic resonance\nmodes of these spin textures by means of the scattered intensity. Most notably,\nthe three eigenmodes of the skyrmion lattice are detected with large\nsensitivity. As this novel technique, which we label REXS-FMR, is carried out\nat distinct positions in reciprocal space, it allows to distinguish\ncontributions originating from different magnetic states, providing information\non the precise character, weight and mode mixing as a prerequisite of tailored\nexcitations for applications."
    },
    {
        "anchor": "3D and 4D printing in dentistry and maxillofacial surgery: Recent\n  advances and future perspectives: 3D and 4D printing are cutting-edge technologies for precise and expedited\nmanufacturing of objects ranging from plastic to metal. Recent advances in 3D\nand 4D printing technologies in dentistry and maxillofacial surgery enable\ndentists to custom design and print surgical drill guides, temporary and\npermanent crowns and bridges, orthodontic appliances and orthotics, implants,\nmouthguards for drug delivery. In the present review, different 3D printing\ntechnologies available for use in dentistry are highlighted together with a\ncritique on the materials available for printing. Recent reports of the\napplication of these printed platformed are highlighted to enable readers\nappreciate the progress in 3D/4D printing in dentistry.",
        "positive": "Electric Field Induced Topological Phase Transition in Two-Dimensional\n  Few-layer Black Phosphorus: Phosphorene is a novel two-dimensional material that can be isolated through\nmechanical exfoliation from layered black phosphorus, but unlike graphene and\nsilicene, monolayer phosphorene has a large band gap. It was thus unsuspected\nto exhibit band inversion and the ensuing topological insulator behavior. It\nhas recently attracted interest because of its proposed application as field\neffect transistors. Using first-principles calculations with applied\nperpendicular electric field F we predict a continuous transition from the\nnormal insulator to a topological insulator and eventually to a metal as a\nfunction of F. The continuous tuning of topological behavior with electric\nfield would lead to spin-separated, gapless edge states, i.e., quantum spins\nHall effect. This finding opens the possibility of converting normal insulating\nmaterials into topological ones via electric field, and making a\nmulti-functional field effect topological transistor that could manipulate\nsimultaneously both spins and charge carrier."
    },
    {
        "anchor": "Highly Efficient Hydrogen Storage of Sc Decorated Biphenylene Monolayer\n  near Ambient-temperature: An Ab-initio Simulation: The energy demands for the growing development of society need to be catered\nwith alternative and green fuels like hydrogen energy for a lasting and\nsustainable culture. One essential component of the hydrogen economy is the\nefficiency of its storage. We have studied the hydrogen-storage capability on a\nrecently synthesized Biphenylene (BPh) decorated with Sc using the\nfirst-principles density functional theory (DFT) and ab-initio molecular\ndynamics (AIMD) techniques. Scandium attaches BPh sheet strongly with binding\nenergy -3.84 eV, and single Sc decorated on BPh can absorb a maximum of five\nH$_2$ molecules resulting in a high gravimetric weight percentage of 11.07,\nwhich is significantly higher than DoE's ultimate criteria (6.5 wt%). Using\nvan't Hoff equation, strongly and weakly attached hydrogens correspond to\ndesorption temperatures of 200 K and 397 K with an average of 305 K. The high\nbinding of Sc to BPh is due to charge donation of 3d orbital of Sc to 2p\norbital of C. The interactions between absorbed H$_2$ and BPh+Sc are due to\ncharge transfer from 3d-orbital of Sc to ${\\sigma}$* bond of H$_2$ molecules\nand backdonation from ${\\sigma}$ bond of H$_2$ to empty 3d-orbital of Sc known\nas Kubas type interaction. Furthermore, phonon and AIMD simulation confirm\nBPh+Sc stability, and the presence of an energy barrier shows no probability of\nSc-Sc clustering on BPh. So theoretically stable BPh+Sc showing high\ngravimetric weight percentage with an average 305 K desorption temperature,\nmight be a potential candidate for solidstage hydrogen devices.",
        "positive": "Unveiling the effect of Ni on the formation and structure of Earth's\n  inner core: Ni is the second most abundant element in the Earth's core. Yet, its effects\non the inner core's structure and formation process are usually disregarded\nbecause of its electronic and size similarity with Fe. Using ab initio\nmolecular dynamics simulations, we find that the bcc phase can spontaneously\ncrystallize in liquid Ni at temperatures above Fe's melting point at inner core\npressures. The melting temperature of Ni is shown to be 700-800 K higher than\nthat of Fe at 323-360 GPa. hcp, bcc, and liquid phase relation differ for Fe\nand Ni. Ni can be a bcc stabilizer for Fe at high temperatures and inner core\npressures. A small amount of Ni can accelerate Fe's crystallization at core\npressures. These results suggest Ni may substantially impact the structure and\nformation process of the solid inner core."
    },
    {
        "anchor": "Griffiths phase and spontaneous exchange bias in\n  La$_{1.5}$Sr$_{0.5}$CoMn$_{0.5}$Fe$_{0.5}$O$_{6}$: La$_{1.5}$Sr$_{0.5}$CoMn$_{0.5}$Fe$_{0.5}$O$_{6}$ (LSCMFO) compound was\nprepared by solid state reaction and its structural, electronic and magnetic\nproperties were investigated. The material forms in rhombohedral $R\\bar{3}c$\nstructure, and the presence of distinct magnetic interactions leads to the\nformation of a Griffiths phase above its FM transition temperature (150 K),\npossibly related to the nucleation of small short-ranged ferromagnetic\nclusters. At low temperatures, a spin glass-like phase emerges and the system\nexhibits both the conventional and the spontaneous exchange bias (EB) effects.\nThese results resemble those reported for La$_{1.5}$Sr$_{0.5}$CoMnO$_{6}$ but\nare discrepant to those found when Fe partially substitutes Co in\nLa$_{1.5}$Sr$_{0.5}$(Co$_{1-x}$Fe$_{x}$)MnO$_{6}$, for which the EB effect is\nobserved in a much broader temperature range. The unidirectional anisotropy\nobserved for LSCMFO is discussed and compared with those of resembling\ndouble-perovskite compounds, being plausibly explained in terms of its\nstructural and electronic properties.",
        "positive": "Compositional disorder and tranport peculiarities in the amorphous\n  indium-oxides: (abridged) We present results of the disorder-induced\nmetal-insulator-transition (MIT) in three-dimensional amorphous indium-oxide\nfilms. The amorphous version studied here differs from the one reported earlier\n[PRB 46, 10917 (1992)] in that it has a much lower carrier concentration. As a\nmeasure of the static disorder we use the dimensionless parameter kFl. Thermal\nannealing is employed as the experimental handle to tune the disorder. On the\nmetallic side of the transition, the low temperature transport exhibits\nweak-localization and electron-electron correlation effects characteristic of\ndisordered electronic systems. The MIT occurs at a kFl~0.3 for both versions of\nthe amorphous material. However, in contrast with the results obtained on the\nelectron-rich version of this system, no sign of superconductivity is seen down\nto ~0.3K even for the most metallic sample used in the current study. This\ndemonstrates that using kFl as a disorder parameter for the\nsuperconductor-insulator-transition (SIT) is an ill defined procedure. A\nmicrostructural study of the films, employing high resolution chemical\nanalysis, gives evidence for spatial fluctuations of the stoichiometry. This\nbrings to light that, while the films are amorphous and show excellent\nuniformity in transport measurements of macroscopic samples, they contain\ncompositional fluctuations that extend over mesoscopic scales. It is argued\nthat this compositional disorder may be the reason for the apparent violation\nof the Ioffe-Regel criterion in the two versions of the amorphous indium-oxide.\nHowever, more dramatic effects due to this disorder are expected when\nsuperconductivity sets in, which are in fact consistent with the prominent\ntransport anomalies observed in the electron-rich version of indium-oxide. The\nrelevance of compositional disorder to other systems near their SIT is\ndiscussed."
    },
    {
        "anchor": "Fermi level tuning and a large activation gap achieved in the\n  topological insulator Bi_{2}Te_{2}Se by Sn doping: We report the effect of Sn doping on the transport properties of the\ntopological insulator Bi_{2}Te_{2}Se studied in a series of\nBi_{2-x}Sn_{x}Te_{2}Se crystals with 0 \\leq x \\leq 0.02. The undoped\nstoichiometric compound (x = 0) shows an n-type metallic behavior with its\nFermi level pinned to the conduction band. In the doped compound, it is found\nthat Sn acts as an acceptor and leads to a downshift of the Fermi level. For x\n\\geq 0.004, the Fermi level is lowered into the bulk forbidden gap and the\ncrystals present a resistivity considerably larger than 1 Ohmcm at low\ntemperatures. In those crystals, the high-temperature transport properties are\nessentially governed by thermally-activated carriers whose activation energy is\n95-125 meV, which probably signifies the formation of a Sn-related impurity\nband. In addition, the surface conductance directly obtained from the\nShubnikov-de Haas oscillations indicates that a surface-dominated transport can\nbe achieved in samples with several um thickness.",
        "positive": "A Tutorial on Advanced Dynamic Monte Carlo Methods for Systems with\n  Discrete State Spaces: Advanced algorithms are necessary to obtain faster-than-real-time dynamic\nsimulations in a number of different physical problems that are characterized\nby widely disparate time scales. Recent advanced dynamic Monte Carlo algorithms\nthat preserve the dynamics of the model are described. These include the\n$n$-fold way algorithm, the Monte Carlo with Absorbing Markov Chains (MCAMC)\nalgorithm, and the Projective Dynamics (PD) algorithm. To demonstrate the use\nof these algorithms, they are applied to some simplified models of dynamic\nphysical systems. The models studied include a model for ion motion through a\npore such as a biological ion channel and the metastable decay of the\nferromagnetic Ising model. Non-trivial parallelization issues for these dynamic\nalgorithms, which are in the class of parallel discrete event simulations, are\ndiscussed. Efforts are made to keep the article at an elementary level by\nconcentrating on a simple model in each case that illustrates the use of the\nadvanced dynamic Monte Carlo algorithm."
    },
    {
        "anchor": "Dewetting of solid films with substrate mediated evaporation: The dewetting dynamics of an ultrathin film is studied in the presence of\nevaporation - or reaction - of adatoms on the substrate. KMC simulations are in\ngood agreement with an analytical model with diffusion, rim facetting, and\nsubstrate sublimation. As sublimation is increased, we find a transition from\nthe usual dewetting regime where the front slows down with time, to a\nsublimation-controlled regime where the front velocity is approximately\nconstant. The rim width exhibits an unexpected non-monotonous behavior, with a\nmaximum in time.",
        "positive": "Spin-transfer physics and the model of ferromagnetism in (Ga,Mn)As: We describe recent progress and open questions in the physics of\ncurrent-induced domain-wall displacement and creep in (Ga,Mn)As. Furthermore,\nthe reasons are recalled why, despite strong disorder and localization, the p-d\nZener model is suitable for the description of this system."
    },
    {
        "anchor": "Strain-tunable energy band parameters of graphene-like GaN: We present ab initio calculations on the effect of in-plane equi-biaxial\nstrain on the structural and electronic properties of hypothetical\ngraphene-like GaN monolayer (ML-GaN). It was found that ML-GaN got buckled for\ncompressive strain in excess of 7.281 %; buckling parameter increased\nquadratic-ally with compressive strain. The 2D bulk modulus of ML-GaN was found\nto be smaller than that of graphene and graphene-like ML-BN, which reflects\nweaker bond in ML-GaN. More importantly, the band gap and effective masses of\ncharge carriers in ML-GaN were found to be tunable by application of in-plane\nequi-biaxial strain. In particular, when compressive biaxial strain of about 3\n% was reached, a transition from indirect to direct band gap-phase occurred\nwith significant change in the value and nature of effective masses of charge\ncarriers; buckling and tensile strain reduced the band gap - the band gap\nreduced to 50 % of its unstrained value at 6.36 % tensile strain and to 0 eV at\nan extrapolated tensile strain of 12.72 %, which is well within its predicted\nultimate tensile strain limit of 16 %. These predictions of strain-engineered\nelectronic properties of highly strain sensitive ML-GaN may be exploited in\nfuture for potential applications in strain sensors and other nano-devices such\nas the nano-electromechanical systems (NEMS).",
        "positive": "Condensation Droplet Sieve: Large droplets emerging during dropwise condensation impair surface\nproperties such as anti-fogging/frosting ability and heat transfer efficiency.\nHow to spontaneously detach massive randomly distributed droplets with\ncontrolled sizes has remained a great challenge. Herein, we present a general\nsolution called condensation droplet sieve, through fabricating microscale\nthin-walled lattice (TWL) structures coated with a superhydrophobic layer.\nGrowing droplets were observed to jumped off this TWL surface with 100%\nprobability once becoming slightly larger than the lattices. The maximum radius\nand residual volume of droplets were strictly confined to 16 {\\mu}m and 3.2\nnl/mm2 respectively, greatly surpassing the current state of the art. We reveal\nthat this extremely efficient jumping is attributed to the large tolerance of\ncoalescence mismatch and effective isolation of droplets between neighbouring\nlattices. Our work provides a new perspective for the design and fabrication of\nhigh-performance anti-dew materials."
    },
    {
        "anchor": "First principle calculation of the effective Zeeman's couplings in\n  topological materials: In this paper, we propose a first principle calculation method for the\neffective Zeeman's coupling based on the second perturbation theory and apply\nit to a few topological materials. For Bi and Bi$_2$Se$_3$, our numerical\nresults are in good accord with the experimental data; for Na$_3$Bi, TaN, and\nZrTe$_5$, the structure of the multi-bands Zeeman's couplings are discussed.\nEspecially, we discuss the impact of Zeeman's coupling on the Fermi surface's\ntopology in Na$_3$Bi in detail.",
        "positive": "Local-global mode interaction in stringer-stiffened plates: A recently developed nonlinear analytical model for axially loaded\nthin-walled stringer-stiffened plates based on variational principles is\nextended to include local buckling of the main plate. Interaction between the\nweakly stable global buckling mode and the strongly stable local buckling mode\nis highlighted. Highly unstable post-buckling behaviour and a progressively\nchanging wavelength in the local buckling mode profile is observed under\nincreasing compressive deformation. The analytical model is compared against\nboth physical experiments from the literature and finite element analysis\nconducted in the commercial code Abaqus; excellent agreement is found both in\nterms of the mechanical response and the predicted deflections."
    },
    {
        "anchor": "Comment on \"Repulsive Casimir Force in Chiral Metamaterials\": It is shown that the proposal of Ref. [1] of Casimir repulsion and\nnanolevitation based on chiral metamaterials is incompatible with the passivity\nand causality of the materials.",
        "positive": "Exchange Bias Effects in Iron Oxide-Based Nanoparticle Systems: The exploration of exchange bias (EB) on the nanoscale provides a novel\napproach to improving the anisotropic properties of magnetic nanoparticles for\nprospective applications in nanospintronics and nanomedicine. However, the\nphysical origin of EB is not fully understood. Recent advances in chemical\nsynthesis provide a unique opportunity to explore EB in a variety of iron\noxide-based nanostructures ranging from core/shell to hollow and hybrid\ncomposite nanoparticles. Experimental and atomistic Monte Carlo studies have\nshed light on the roles of interface and surface spins in these nanosystems.\nThis review paper aims to provide a thorough understanding of the EB and\nrelated phenomena in iron oxide-based nanoparticle systems, knowledge of which\nis essential to tune the anisotropic magnetic properties of exchange-coupled\nnanoparticle systems for potential applications."
    },
    {
        "anchor": "Phase stability, ordering tendencies, and magnetism in single-phase fcc\n  Au-Fe nanoalloys: Bulk Au-Fe alloys separate into Au-based fcc and Fe-based bcc phases, but\nL1$_0$ and L1$_2$ orderings were reported in single-phase Au-Fe nanoparticles.\nMotivated by these observations, we study the structural and ordering\nenergetics in this alloy by combining density functional theory (DFT)\ncalculations with effective Hamiltonian techniques: a cluster expansion with\nstructural filters, and the configuration-dependent lattice deformation model.\nThe phase separation tendency in Au-Fe persists even if the fcc-bcc\ndecomposition is suppressed. The relative stability of disordered bcc and fcc\nphases observed in nanoparticles is reproduced, but the fully ordered L1$_0$\nAuFe, L1$_2$ Au$_3$Fe, and L1$_2$ AuFe$_3$ structures are unstable in DFT.\nHowever, a tendency to form concentration waves at the corresponding [001]\nordering vector is revealed in nearly-random alloys in a certain range of\nconcentrations. This incipient ordering requires enrichment by Fe relative to\nthe equiatomic composition, which may occur in the core of a nanoparticle due\nto the segregation of Au to the surface. Effects of magnetism on the chemical\nordering are also discussed.",
        "positive": "Oxidation states, Thouless' pumps, and non-trivial ionic transport in\n  non-stoichiometric electrolytes: Thouless' quantization of adiabatic particle transport permits to associate\nan integer topological charge with each atom of an electronically gapped\nmaterial. If these charges are additive and independent of atomic positions,\nthey provide a rigorous definition of atomic oxidation states and atoms can be\nidentified as integer-charge carriers in ionic conductors. Whenever these\nconditions are met, charge transport is necessarily convective, i.e. it cannot\noccur without substantial ionic flow, a transport regime that we dub trivial.\nWe show that the topological requirements that allow these conditions to be\nbroken are the same that would determine a Thouless' pump mechanism if the\nsystem were subject to a suitably defined time-periodic Hamiltonian. The\noccurrence of these requirements determines a non-trivial transport regime\nwhereby charge can flow without any ionic convection, even in electronic\ninsulators. These results are first demonstrated with a couple of simple\nmolecular models that display a quantum pump mechanism upon introduction of a\nfictitious time dependence of the atomic positions along a closed loop in\nconfiguration space. We finally examine the impact of our findings on the\ntransport properties of non-stoichiometric alkali-halide melts, where the same\ntopological conditions that would induce a quantum pump mechanism along certain\nclosed loops in configuration space also determine a non-trivial transport\nregime such that most of the total charge current results to be uncorrelated\nfrom the ionic ones."
    },
    {
        "anchor": "Ab initio elasticity at finite temperature and stress in ferroelectrics: Computing the temperature and stress dependence of the full elastic constant\ntensor from first-principles in non-cubic materials remains a challenging\nproblem. Here we circumvent the aforementioned challenge via the generalized\nquasiharmonic approximation in conjunction with the irreducible derivative\napproach for computing strain dependent phonons using finite difference,\nexplicitly including dipole-quadrupole contributions. We showcase this approach\nin ferroelectric PbTiO$_3$ using density functional theory, computing all\nindependent elastic constants and piezoelectric strain coefficients at finite\ntemperature and stress. There is good agreement between the quasiharmonic\napproximation and the experimental lattice parameters close to 0 K. However,\nthe quasiharmonic approximation overestimates the temperature dependence of the\nlattice parameters and elastic constant tensor, demonstrating that a higher\nlevel of strain dependent anharmonic vibrational theory is needed.",
        "positive": "Low Temperature Magnetic Studies on PbFe0.5Nb0.5O3 Multiferroic: The PbFe0.5Nb0.5O3 (PFN), a well-known A(B'1/2B\"1/2)O3 type multiferroic was\nsuccessfully synthesized in single phase by a single step solid state reaction\nmethod. The single phase PFN was characterized through XRD, microstructure\nthrough SEM, and magnetic studies were carried out through temperature\ndependent vibrating sample magnetometer (VSM) and neutron diffraction (ND)\nmeasurements. PFN exhibits a cusp at around 150 K in the temperature dependent\nmagnetic susceptibility corresponding to the N\\'eel temperature (TN1) and\nanother peak around 10 K (TN2) corresponding to spin-glass like transition. In\nthe temperature dependent ND studies, a magnetic Bragg peak appears at Q = 1.35\n{\\AA}-1 (where Q = 4{\\pi}sin theeta/lambda, is called the scattering vector)\nbelow TN (150 K) implying antiferromagnetic (AFM) ordering in the system. On\nthe basis of Rietveld analysis of the ND data at T = 2 K, the magnetic\nstructure of PFN could be explained by a G-type antiferromagnetic structure."
    },
    {
        "anchor": "Powerful and Tunable THz Emitters Based on the Fe/Pt Magnetic\n  Heterostructure: In this work, we report our study on the THz emission in Fe/Pt magnetic\nheterostructures. We have carried out a comprehensive investigation of THz\nemission from Fe/Pt magnetic heterostructures, employing time-domain THz\nspectroscopy. We reveal that by properly tuning the thickness of Fe or Pt\nlayer, THz emission can be greatly improved in this type of heterostructure. We\nfurther demonstrate that the THz field strength emitted from a newly designed\nmultilayer (Pt/Fe/MgO)$_n$ with n=3 can reach a value of ~1.6 kV/cm, which is\ncomparable to the values from the conventional GaAs antenna with a bias of 4\nkV/cm, and the nonlinear crystals, e.g., 100 micrometer GaP and 2 mm ZnTe. For\nthe first time, the intensity and spectrum of THz wave is demonstrated to be\ntunable by the magnetic field applied on the patterned magnetic Fe/Pt\nheterostructures. These findings thus promise novel approaches to fabricate\npowerful and tunable THz emitters based on magnetic heterostructure.",
        "positive": "Magnetoelectro-elastic control of magnetism in an artificial\n  multiferroic: We study the coexistence of strain- and charge-mediated magnetoelectric\ncoupling in a cobalt (0-7 nm) wedge on ferroelectric\n[Pb(Mg$_{1/3}$/Nb$_{2/3}$)O$_{3}$]$_{0.68}$-[PbTiO$_{3}$]$_{0.32}$ (011) using\nsurface-sensitive x-ray magnetic circular dichroism spectroscopy at the Co\nL$_{3,2}$ edges. Three distinct electric field driven remanent magnetization\nstates can be set in the Co film at room temperature. Ab-initio density\nfunctional theory calculations unravel the relative contributions of both\nstrain and charge to the observed magnetic anisotropy changes illustrating\nmagnetoelectro-elastic coupling at artificial multiferroic interfaces."
    },
    {
        "anchor": "New 3,3'-(ethane-1, 2-diylidene)bis(indolin-2-one) (EBI)-based small\n  molecule semiconductors for organic solar cells: A series of donor-acceptor-donor (D-A-D) structured small-molecule compounds,\nwith 3,3'-(ethane-1,2-diylidene)bis(indolin-2-one) (EBI) as a novel electron\nacceptor building block coupled with various electron donor end-capping\nmoieties (thiophene, bithiophene and benzofuran), were synthesized and\ncharacterized. When the fused-ring benzofuran is combined to EBI (EBI-BF), the\nmolecules displayed a perfectly planar conformation and afforded the best\ncharge tranport properties among these EBI compounds with a hole mobility of up\nto 0.021 cm2 V-1 s-1. All EBI-based small molecules were used as donor material\nalong with a PC61BM acceptor for the fabrication of solution-processed\nbulk-heterojunction (BHJ) solar cells. The best performing photovoltaic devices\nare based on the EBI derivative using the bithiophene end-capping moiety\n(EBI-2T) with a maximum power conversion efficiency (PCE) of 1.92%, owing to\nthe broad absorption spectra of EBI-2T and the appropriate morphology of the\nBHJ. With the aim of establishing a correlation between the molecular structure\nand the thin film morphology, differential scanning calorimetry, atomic force\nmicroscopy and X-ray diffraction analysis were performed on neat and blend\nfilms of each material.",
        "positive": "Mechanical behavior, bonding nature, and defect processes of Mo2ScAlC2:\n  a new ordered MAX phase: In the present study we employed density functional theory calculations to\ninvestigate the mechanical behavior, bonding nature and defect processes of the\nnew ordered MAX phase Mo2ScAlC2. The mechanical stability of the compound is\nverified with its single crystal elastic constants. The new phase Mo2ScAlC2 is\nanticipated to be prone to shear along the crystallographic b and c axes, when\na rational force is applied to the crystallographic a axis. The compressibility\nalong the <001> direction under uniaxial stress is expected to be easier in\nMo2ScAlC2. Additionally, the volume deformation should be easier in Mo2ScAlC2\nthan in the isostructural Mo2TiAlC2. Mo2ScAlC2 is predicted to behave in a\nbrittle manner. Due to its higher Debye temperature, Mo2ScAlC2 is expected to\nbe thermally more conductive than Mo2TiAlC2. The cross-slip pinning procedure\nshould be significantly easier in Mo2ScAlC2 as compared to Mo2TiAlC2. The new\nordered MAX phase Mo2ScAlC2 has a mixed character of strong covalent and\nmetallic bonding with limited ionic nature. Both Mo-C and Mo-Al bonds are\nexpected to be more covalent in Mo2ScAlC2 than those of Mo2TiAlC2. the level of\ncovalency of Sc-C bond is somewhat low compared to a similar bond Ti-C in\nMo2TiAlC2. Due to its reduced hardness, Mo2ScAlC2 should be softer and more\neasily machinable compared to Mo2TiAlC2. Fermi surface topology of the new\ncompound is formed mainly due to the low-dispersive Mo 4d-like bands. The\nintrinsic defect processes reveal that the level of radiation tolerance in\nMo2ScAlC2 is not as high as in other MAX phases such as Ti3AlC2."
    },
    {
        "anchor": "Unraveling the dislocation core structure at a van der Waals gap in\n  bismuth telluride: Tetradymite-structured chalcogenides such as bismuth telluride Bi_{2}Te_{3}\nare of significant interest for thermoelectric energy conversion and as\ntopological insulators. Dislocations play a critical role during synthesis and\nprocessing of such materials and can strongly affect their functional\nproperties. The dislocations between quintuple layers present special interest\nsince their core structure is controlled by the van der Waals interactions\nbetween the layers. In this work, using atomic-resolution electron microscopy,\nwe resolve the basal dislocation core structure in Bi_{2}Te_{3}, quantifying\nthe disregistry of the atomic planes across the core. We show that, despite the\nexistence of a stable stacking fault in the basal plane gamma surface, the\ndislocation core spreading is mainly due to the weak bonding between the\nlayers, which leads to a small energy penalty for layer sliding parallel to the\nvan der Waals gap. Calculations within a semidiscrete variational\nPeierls-Nabarro model informed by first-principles calculations support our\nexperimental findings.",
        "positive": "Enhanced flexural wave sensing by adaptive gradient-index metamaterials: Increasing sensitivity and signal to noise ratios of conventional wave\nsensors is an interesting topic in structural health monitoring, medical\nimaging, aerospace and nuclear instrumentation. Here, we report the concept of\na gradient piezoelectric self-sensing system by integrating shunting circuitry\ninto conventional sensors. By tuning circuit elements properly, both the\nquality and quantity of the flexural wave measurement data can be significantly\nincreased for new adaptive sensing applications. Through analytical, numerical\nand experimental studies, we demonstrate that the metamaterial-based sensing\nsystem (MBSS) with gradient bending stiffness can be designed by connecting\ngradient negative capacitance circuits to an array of piezoelectric patches\n(sensors). We further demonstrate that the proposed system can achieve more\nthan two orders of magnitude amplification of flexural wave signals to overcome\nthe detection limit. This research encompasses fundamental advancements in the\nMBSS with improved performance and functionalities, and will yield significant\nadvances for a range of applications."
    },
    {
        "anchor": "Interpretability of machine-learning models in physical sciences: In machine learning (ML), it is in general challenging to provide a detailed\nexplanation on how a trained model arrives at its prediction. Thus, usually we\nare left with a black-box, which from a scientific standpoint is not\nsatisfactory. Even though numerous methods have been recently proposed to\ninterpret ML models, somewhat surprisingly, interpretability in ML is far from\nbeing a consensual concept, with diverse and sometimes contrasting motivations\nfor it. Reasonable candidate properties of interpretable models could be model\ntransparency (i.e. how does the model work?) and post hoc explanations (i.e.,\nwhat else can the model tell me?). Here, I review the current debate on ML\ninterpretability and identify key challenges that are specific to ML applied to\nmaterials science.",
        "positive": "Blocking temperature of interacting magnetic nanoparticles with uniaxial\n  and cubic anisotropies from Monte Carlo simulations: The low temperature behavior of densely packed interacting spherical single\ndomain nanoparticles (MNP) is investigated by Monte Carlo simulations in the\nframework of an effective one spin model. The particles are distributed through\na hard sphere like distribution with periodic boundary conditions and interact\nthrough the dipole dipole interaction (DDI) with an anisotropy energy including\nboth cubic and uniaxial symmetry components. The cubic component is shown to\nplay a sizable role on the value of the blocking temperature $T_b$ only when\nthe MNP easy axes are parallel to the cubic easy direction ([111] direction for\na negative cubic anisotropy constant). The nature of the collective low\ntemperature state, either ferromagnetic or spin glass like, is found to depend\non the ratio of the anisotropy to the dipolar energies characterizing partly\nthe disorder in the system."
    },
    {
        "anchor": "Experimental realization of single-plaquette gauge flux insertion and\n  topological Wannier cycles: Gauge fields are at the heart of the fundamental science of our universe and\nvarious materials. For instance, Laughlin's gedanken experiment of gauge flux\ninsertion played a major role in understanding the quantum Hall effects. Gauge\nflux insertion into a single unit-cell, though crucial for detecting exotic\nquantum phases and for the ultimate control of quantum dynamics and classical\nwaves, however, has not yet been achieved in laboratory. Here, we report on the\nexperimental realization of gauge flux insertion into a single plaquette in a\nlattice system with the gauge phase ranging from 0 to 2pi which is realized\nthrough a novel approach based on three consecutive procedures: the dimension\nextension, creating an engineered dislocation and the dimensional reduction.\nFurthermore, we discover that the single-plaquette gauge flux insertion leads\nto a new phenomenon termed as the topological Wannier cycles, i.e., the cyclic\nspectral flows across multiple band gaps which are manifested as the\ntopological boundary states (TBSs) on the plaquette. Such topological Wannier\ncycles emerge only if the Wannier centers are enclosed by the flux-carrying\nplaquette. Exploiting acoustic metamaterials and versatile pump-probe\nmeasurements, we observe the topological Wannier cycles by detecting the TBSs\nin various ways and confirm the single-plaquette gauge flux insertion by\nmeasuring the gauge phase accumulation on the plaquette. Our work unveils an\nunprecedented regime for lattice gauge systems and a fundamental topological\nresponse which could empower future studies on artificial gauge fields and\ntopological materials.",
        "positive": "The origin and properties of the wetting layer and early evolution of\n  epitaxially strained thin films: We showed that a wetting layer in epitaxially strained thin films which\ndecreases with increasing lattice mismatch strain arises due to the variation\nof nonlinear elastic free energy with film thickness. We calculated how and at\nwhat thickness a flat film becomes unstable to perturbations of varying size\nfor films with both isotropic and anisotropic surface tension. We showed that\nanisotropic surface tension gives rise to a metastable enlarged wetting layer.\nThe perturbation amplitude needed to destabilize this wetting layer decreases\nwith increasing lattice mismatch. We also studied the early evolution of\nepitaxially strained films. We found that film growth is dependent on the mode\nof material deposition. The growth of a perturbation in a flat film is found to\nobey robust scaling relations. These scaling relations differ for isotropic and\nanisotropic surface tension."
    },
    {
        "anchor": "Highly accurate local basis sets for large-scale DFT calculations in\n  CONQUEST: Given the widespread use of density functional theory (DFT), there is an\nincreasing need for the ability to model large systems (beyond 1,000 atoms). We\npresent a brief overview of the large-scale DFT code Conquest, which is capable\nof modelling such large systems, and discuss approaches to the generation of\nconsistent, well-converged pseudo-atomic basis sets which will allow such large\nscale calculations. We present tests of these basis sets for a variety of\nmaterials, comparing to fully converged plane wave results using the same\npseudopotentials and grids.",
        "positive": "Charge density and redox potential of LiNiO2 using ab initio diffusion\n  quantum Monte Carlo: Electronic structure of layered LiNiO2 has been controversial despite\nnumerous theoretical and experimental reports regarding its nature. We\ninvestigate the charge densities, lithium intercalation potentials and Li\ndiffusion barrier energies of LixNiO2 (0.0 < x < 1.0) system using a truly\nab-initio method, diffusion quantum Monte Carlo (DMC). We compare the charge\ndensities from DMC and density functional theory (DFT) and show that local and\nsemi-local DFT functionals yield spin polarization densities with incorrect\nsign on the oxygen atoms. SCAN functional and Hubbard-U correction improves the\npolarization density around Ni and O atoms, resulting in smaller deviations\nfrom the DMC densities. DMC accurately captures the p-d hybridization between\nthe Ni-O atoms, yielding accurate lithium intercalation voltages, polarization\ndensities and reaction barriers."
    },
    {
        "anchor": "Bonding-aware Materials Representation for Deep Learning Atomistic\n  Models: Deep potentials for molecular dynamics (MD) achieve first-principles accuracy\nat much lower computational cost. However, their use in large length- and\ntime-scale simulations is limited by their lower speeds compared to analytical\natomistic potentials, primarily due to network complexity and long embedding\ntime. Here, based on the moments theorem, we develop a chemical-bonding-aware\nembedding for neural network potentials that achieve state-of-the-art accuracy\nin forces and local electronic density of states prediction with an ultrasmall\n16x32 neural network resulting in significantly lower computational cost.",
        "positive": "Zinc Oxide - From Dilute Magnetic Doping to Spin Transport: During the past years there has been renewed interest in the wide-bandgap\nII-VI semiconductor ZnO, triggered by promising prospects for spintronic\napplications. First, ferromagnetism was predicted for dilute magnetic doping.\nIn comprehensive investigation of ZnO:Co thin films based on the combined\nmeasurement of macroscopic and microscopic properties, we find no evidence for\ncarrier-mediated itinerant ferromagnetism. Phase-pure, crystallographically\nexcellent ZnO:Co is uniformly paramagnetic. Superparamagnetism arises when\nphase separation or defect formation occurs, due to nanometer-sized metallic\nprecipitates. Other compounds like ZnO:(Li,Ni) and ZnO:Cu do not exhibit\nindication of ferromagnetism.\n  Second, its small spin-orbit coupling and correspondingly large spin\ncoherence length makes ZnO suitable for transporting or manipulating spins in\nspintronic devices. From optical pump/optical probe experiments, we find a spin\ndephasing time of the order of 15 ns at low temperatures which we attribute to\nelectrons bound to Al donors. In all-electrical magnetotransport measurements,\nwe successfully create and detect a spin-polarized ensemble of electrons and\ntransport this spin information across several nanometers. We derive a spin\nlifetime of 2.6 ns for these itinerant spins at low temperatures, corresponding\nwell to results from an electrical pump/optical probe experiment."
    },
    {
        "anchor": "A Mini Review on The Applications of Nanomaterials in Forensic Science: Herein, we report a minireview to give a brief introduction of applications\nof nanomaterials in the field of forensic science. The materials that have\ntheir size in nanoscale (1 - 100 nm) comes under the category of nanomaterials.\nNanomaterials possess various applications in different fields like cosmetic\nproduction, medical, photoconductivity etc. because of their physio-chemical,\nelectrical and magnetic properties. Due to the different characteristic\nproperty that nanomaterials have, they are widely employed in diverse domains.\nIn various fields of forensic science such as fingerprints, toxicology,\nmedicine, serology, nanomaterials are being used extensively. Large surface\narea to volume ratio of the materials in nano-regime makes the nanomaterials\nsuitable for all these application with high efficiency. This review article\nbriefs about the nanomaterials, their advantages and their novel applications\nin various fields, focusing especially in the field of forensic science. The\nbasic idea of different areas of forensic science such as development of\nfingerprints, detection of drugs, estimating the time since death, analysis of\nGSR, detection of various explosives and for the extraction of DNA etc. has\nalso been provided.",
        "positive": "Bohr's correspondence principle for atomic transport calculations: In this work we perform a comparison between Classical Molecular Static (CMS)\nand quantum Density Functional Theory (DFT) calculations in order to obtain the\ndiffusion coefficients for diluted \\emph{Fe-Cr} alloys. We show that, in\naccordance with Bohr's correspondence principle, as the size of the atomic cell\n(total number of atoms) is increased, quantum results with DFT approach to the\nclassical ones obtained with CMS. Quantum coherence effects play a crucial role\nin the difference arising between CMS and DFT calculations. Also, thermal\ncontact with the environment destroys quantum coherent effects making the\nclassical behavior to emerge. Indeed, CMS calculations are in good agreement\nwith available experimental data. We claim that, the atomic diffusion process\nin metals is a classical phenomena. Then, if reliable semi empirical potentials\nare available, a classical treatment of the atomic transport in metals is much\nconvenient than DFT."
    },
    {
        "anchor": "Multiple Pathways in NaCl Homogeneous Crystal Nucleation: NaCl crystal nucleation from metastable solutions has long been considered to\noccur according to a single-step mechanism. Recent experimental observations\nsuggest that NaCl crystals emerge from disordered intermediates which is\nseemingly at odds with this established view. Here, we performed biased and\nunbiased molecular dynamics simulations to analyse and characterise the\npathways to crystalline phases from solutions far into the metastable region.\nWe find that large liquid-like NaCl clusters emerge as the solution\nconcentration is increased and two-step nucleation pathways are more dominant\nthan one-step pathways to phase separation. Analyses of cluster size\npopulations and the ion pair association constant show that these clusters are\ntransient, unlike the thermodynamically stable prenulceation cluster solute\nspecies that were suggested in other mineralising systems. A Markov State Model\nwas developed to analyse the mechanisms and timescales for nucleation from\nunbiased molecular dynamics trajectories in a reaction coordinate space\ncharacterising the dense regions in clusters and crystalline order. This\nallowed calculation of the committor probabilities for the system to relax to\nthe solution or crystal states, and to estimate the rate of nucleation, which\nshows excellent agreement with literature values. From a fundamental nucleation\nperspective, our work highlights the need to extend the attribute 'critical' to\nan ensemble of clusters which can display a broad range of structures and\ninclude sizeable disordered domains depending upon the reaction\nconditions.Moreover, our recent simulation studies demonstrated that carbon\nsurfaces catalyse the formation of liquid-like NaCl networks which, combined\nwith the observations here, suggests that alternative pathways beyond the\nsingle-step mechanism can be exploited to control the crystallisation of NaCl.",
        "positive": "Challenges in first-principles NPT molecular dynamics of soft porous\n  crystals: A case study on MIL-53(Ga): Soft porous crystals present a challenge to molecular dynamics simulations\nwith flexible size and shape of the simulation cell (i.e., in the NPT\nensemble), since their framework responds very sensitively to small external\nstimuli. Hence, all interactions have to be described very accurately in order\nto obtain correct equilibrium structures. Here, we report a methodological\nstudy on the nanoporous metal-organic framework MIL-53(Ga), which undergoes a\nlarge-amplitude transition between a narrow- and a large-pore phase upon a\nchange in temperature. Since this system has not been investigated by density\nfunctional theory (DFT)-based NPT simulations so far, we carefully check the\nconvergence of the stress tensor with respect to computational parameters.\nFurthermore, we demonstrate the importance of dispersion interactions and test\ntwo different ways of incorporating them into the DFT framework. As a result,\nwe propose two computational schemes which describe accurately the narrow- and\nthe large-pore phase of the material, respectively. These schemes can be used\nin future work on the delicate interplay between adsorption in the nanopores\nand structural flexibility of the host material."
    },
    {
        "anchor": "Mechanisms of adsorbing hydrogen gas on metal decorated graphene: Hydrogen is a key player in global strategies to reduce greenhouse gas\nemissions. In order to make hydrogen a widely-used fuel, we require more\nefficient methods of storing it than the current standard of pressurized\ncylinders. An alternative method is to adsorb H$_2$ in a material and avoid the\nuse of high pressures. Among many potential materials, layered materials such\nas graphene present a practical advantage as they are lightweight. However,\ngraphene and other 2D materials typically bind H$_2$ too weakly to store it at\nthe typical operating conditions of a hydrogen fuel cell. Modifying the\nmaterial, for example by decorating graphene with adatoms, can strengthen the\nadsorption energy of H$_2$ molecules, but the underlying mechanisms are still\nnot well understood. In this work, we systematically screen alkali and alkaline\nearth metal decorated graphene sheets for the adsorption of hydrogen gas from\nfirst principles, and focus on the mechanisms of binding. We show that there\nare three mechanisms of adsorption on metal decorated graphene and each leads\nto distinctly different hydrogen adsorption structures. The three mechanisms\ncan be described as weak van der Waals physisorption, metal adatom facilitated\npolarization, and Kubas adsorption. Among these mechanisms, we find that Kubas\nadsorption is easily perturbed by an external electric field, providing a way\nto tune H$_2$ adsorption.",
        "positive": "Structural evolution in high-pressure amorphous CO$_2$ from \\textit{ab\n  initio} molecular dynamics: By employing $ab$ $initio$ molecular dynamics simulations at constant\npressure, we investigated behavior of amorphous carbon dioxide between 0-100\nGPa and 200-500 K and found several new amorphous forms. We focused on\nevolution of the high-pressure polymeric amorphous form known as a-carbonia on\nits way down to zero pressure, where it eventually converts into a molecular\namorphous solid. During decompression, two nonmolecular amorphous forms with\ndifferent proportion of three and four-coordinated carbons and two mixed\nmolecular-nonmolecular forms were observed. Transformation from a-carbonia to\nthe molecular state thus appears to proceed discontinuously via several\nintermediate stages suggesting that solid CO$_2$ might exhibit interesting\npolyamorphism. We also studied relations of the amorphous forms to their\ncrystalline counterparts. The tetrahedral-like a-carbonia is most probably\nrelated to phase-V according to their structural properties, while presence of\nthe mixed forms may reflect hypothetical existence of metastable\nthree-coordinated polymeric phase that is composed of linear chains. Our\nmolecular amorphous form seems to be related to phase-I according to molecular\ncoordination and their relative bond orientations."
    },
    {
        "anchor": "Single-Layer MoS2 Phototransistors: A new phototransistor based on the mechanically-exfoliated single-layer MoS2\nnanosheet is fabricated and its light-induced electric properties are\ninvestigated in details. Photocurrent generated from the phototransistor is\nsolely determined by the illuminated optical power at a constant drain or gate\nvoltage. The switching behavior of photocurrent generation and annihilation can\nbe completely finished within ca. 50 ms and it shows good stability.\nEspecially, the single-layer MoS2 phototransistor exhibits a better\nphotoresponsivity as compared with the graphene-based device. The unique\ncharacteristics of incident-light control, prompt photoswitching and good\nphotoresponsivity from the MoS2 phototransistor pave an avenue to develop the\nsingle-layer semiconducting materials for multi-functional optoelectronic\ndevice applications in future.",
        "positive": "Probing the sp^2 dependence of elastic moduli in ultrahard diamond films: The structural and elastic properties of diamond nanocomposites and\nultrananocrystalline diamond films (UNCD) are investigated using both empirical\npotentials and tight binding schemes. We find that both materials are extremely\nhard, but their superb diamondlike properties are limited by their sp^2\ncomponent. In diamond composites, the sp^2 atoms are found in the matrix and\nfar from the interface with the inclusion, and they are responsible for the\nsoftening of the material. In UNCD, the sp^2 atoms are located in the grain\nboundaries. They offer relaxation mechanisms which relieve the strain but, on\nthe other hand, impose deformations that lead to softening. The higher the sp^2\ncomponent the less rigid these materials are."
    },
    {
        "anchor": "Soft Phonon Modes and Diffuse Scattering in\n  Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 Relaxor Ferroelectrics: Single crystals of a ternary relaxor ferroelectric system,\n0.29Pb(In1/2Nb1/2)O3-0.45Pb(Mg1/3Nb2/3)O3-0.26PbTiO3, have been studied using\ntriple-axis based elastic and inelastic neutron scattering. Elastic diffuse\nscattering confirms the presence of polar nano-regions (PNRs) in this system.\nThe PNRs emerge at the Burns temperature, TB = 630 K and then grow continuously\nin population and correlation size as the crystal cools down to 100 K. At 300\nK, characteristic 'butterfly' and ellipsoid shaped diffuse scattering patterns\nare observed on the HK0 reciprocal space plane. Electrical poling along the\n[110] direction produces a marked asymmetry in the diffuse scattering patterns,\nwith the parallel-to-the-field components enhanced while the\nperpendicular-to-the-field components suppressed. Several low energy phonon\nbranches along the [001] and [111] directions were studied. Most significantly,\nthe PNR-acoustic phonon coupling is confirmed for the [110] transverse acoustic\n(TA) phonons polarized along the [1-10] real space direction and the [100] TA\nphonons. This coupling appears to be anisotropic and correlated with the\ndistribution of PNRs, and also affected by the relative length scales of the\nPNRs and phonon wave vectors. The well-known 'waterfall' phenomenon is observed\non the [001] and [110] transverse optical (TO) branches, near the zone center.\nThe optical phonon measurements also reveal a lowest-energy, zone center soft\nTO mode, whose squared phonon energy increase linearly with decreasing\ntemperature below the TB.",
        "positive": "Sub-diffusive electronic states in octagonal tiling: We study the quantum diffusion of charge carriers in octagonal tilings. Our\nnumerical results show a power law decay of the wave-packet spreading, $L(t)\n\\propto t^{\\beta}$, characteristic of critical states in quasicrystals at large\ntime $t$. For many energies states are sub-diffusive, i.e. $\\beta < 0.5$, and\nthus conductivity increases when the amount of defects (static defects and/or\ntemperature) increases."
    },
    {
        "anchor": "Application of the Exact Muffin-Tin Orbitals Theory: the Spherical Cell\n  Approximation: We present a self-consistent electronic structure calculation method based on\nthe {\\it Exact Muffin-Tin Orbitals} (EMTO) Theory developed by O. K. Andersen,\nO. Jepsen and G. Krier (in {\\it Lectures on Methods of Electronic Structure\nCalculations}, Ed. by V. Kumar, O.K. Andersen, A. Mookerjee, Word Scientific,\n1994 pp. 63-124) and O. K. Andersen, C. Arcangeli, R. W. Tank, T.\nSaha-Dasgupta, G. Krier, O. Jepsen, and I. Dasgupta, (in {\\it Mat. Res. Soc.\nSymp. Proc.} {\\bf 491}, 1998 pp. 3-34). The EMTO Theory can be considered as an\n{\\it improved screened} KKR (Korringa-Kohn-Rostoker) method which is able to\ntreat large overlapping potential spheres. Within the present implementation of\nthe EMTO Theory the one electron equations are solved exactly using the Green's\nfunction formalism, and the Poisson's equation is solved within the {\\it\nSpherical Cell Approximation} (SCA). To demonstrate the accuracy of the\nSCA-EMTO method test calculations have been carried out.",
        "positive": "In situ observation the interface undercooling of freezing colloidal\n  suspensions with differential visualization method: Interface undercooling is one of the most significant parameters in the\nsolidification of colloidal suspensions. However, quantitative measurement of\ninterface undercooling of colloidal suspensions is still a challenge. Here, a\nnew experimental facility and gauging method are designed to directly reveal\nthe interface undercooling on both static and dynamic cases. The interface\nundercooling is visualized through the discrepancy of solid/liquid interface\npositions between the suspensions and its solvent in a thermal gradient\napparatus. The resolutions of the experimental facility and gauging method are\nproved to be 0.01 K. The high precision of the method comes from the principle\nof converting temperature measurement into distance measurement in the thermal\ngradient platform. Moreover, both static and dynamic interface undercoolings\ncan be quantitatively measured."
    },
    {
        "anchor": "Enhancement of thermoelectric figure of merit in zigzag graphene\n  nanoribbons with periodic edge vacancies: The influence of periodic edge vacancies and antidot arrays on the\nthermoelectric properties of zigzag graphene nanoribbons is investigated. Using\nthe Green's function method, the tight-binding approximation for the electron\nHamiltonian and the 4th nearest neighbor approximation for the phonon dynamical\nmatrix, we calculate the Seebeck coefficient and the thermoelectric figure of\nmerit. It is found that, at a certain periodic arrangement of vacancies on both\nedges of zigzag nanoribbon, a finite band gap opens and almost twofold\ndegenerate energy levels appear. As a result, a marked increase in the Seebeck\ncoefficient takes place. It is shown that an additional enhancement of the\nthermoelectric figure of merit can be achieved by a combination of periodic\nedge defects with an antidot array.",
        "positive": "An artificial neural network for surrogate modeling of stress fields in\n  viscoplastic polycrystalline materials: The purpose of this work is the development of an artificial neural network\n(ANN) for surrogate modeling of the mechanical response of viscoplastic grain\nmicrostructures. To this end, a U-Net-based convolutional neural network (CNN)\nis trained to account for the history dependence of the material behavior. The\ntraining data take the form of numerical simulation results for the von Mises\nstress field under quasi-static tensile loading. The trained CNN (tCNN) can\naccurately reproduce both the average response as well as the local von Mises\nstress field. The tCNN calculates the von Mises stress field of grain\nmicrostructures not included in the training dataset about 500 times faster\nthan its calculation based on the numerical solution with a spectral solver of\nthe corresponding initial-boundary-value problem. The tCNN is also successfully\napplied to other types of microstructure morphologies (e.g., matrix-inclusion\ntype topologies) and loading levels not contained in the training dataset."
    },
    {
        "anchor": "Chiral surface spin textures in Cu$_2$OSeO$_3$ unveiled by soft x-ray\n  scattering in specular reflection geometry: Resonant elastic soft x-ray magnetic scattering (XRMS) is a powerful tool to\nexplore long-periodic spin textures in single crystals. However, due to the\nlimited momentum transfer range imposed by long wavelengths of photons in the\nsoft x-ray region, Bragg diffraction is restricted to crystals with the large\nlattice parameters. Alternatively, small angle x-ray scattering has been\ninvolved in the soft energy x-ray range which, however, brings in difficulties\nwith the sample preparation that involves focused ion beam milling to thin down\nthe crystal to below a few hundred nm thickness. We show how to circumvent\nthese restrictions by using XRMS in specular reflection from a sub-nanometer\nsmooth crystal surface. The method allows observing diffraction peaks from the\nhelical and conical spin modulations at the surface of a Cu$_2$OSeO$_3$ single\ncrystal and probing their corresponding chirality as contributions to the\ndichroic scattered intensity. The results suggest a promising way to carry out\nXRMS studies on plethora of noncentrosymmetric systems hitherto unexplored with\nsoft x-rays due to the absence of the commensurate Bragg peaks in the available\nmomentum transfer range.",
        "positive": "Empirical Magnetic Structure of Frustrated Spin Systems: Frustrated magnetism plays a central role in the phenomenology of exotic\nquantum states. However, because the magnetic structures of frustrated systems\nare aperiodic, there has always been the problem that they cannot be determined\nusing traditional crystallographic techniques. Here we show that the magnetic\ncomponent of powder neutron scattering data is actually sufficiently\ninformation-rich to drive magnetic structure solution for frustrated systems,\nincluding spin ices, spin liquids, and molecular magnets. Consequently,\nsingle-crystal samples are not prerequisite for detailed characterisation of\nexotic magnetic states. Our methodology employs ab initio reverse Monte Carlo\nrefinement, making informed use of an additional constraint that minimises\nvariance in local spin environments. By refining atomistic spin configurations,\nwe obtain at once (i) a magnetic structure \"solution\" - i.e. the orientation of\nclassical spin vectors - (ii) the spin correlation functions, and (iii) the\nfull three-dimensional magnetic scattering pattern."
    },
    {
        "anchor": "Issues related to the usage of nitrogen as carrier gas for the MOVPE\n  growth of GaSb/InAs heterostructures on InAs pseudosubstrates: GaSb/InAs/GaSb layer stacks have been grown on InAs metamorphic substrates\n(pseudosubstrates) by MOVPE, using nitrogen as major carrier gas. We\ndemonstrate that GaSb growth by nitrogen MOVPE on InAs metamorphic substrates\n(and on InAs wafers) is possible in a very narrow range of growth parameters.\nAs demonstrators, GaSb/InAs/GaSb structures were grown for electron mobility\ntests, obtaining (unintentional) 2D electron gas densities in the order of\n9/5x10e12 cm(e-2) and mobilities up to 1.2/1.8x10e4 cm(e2)/Vs at room and\nliquid nitrogen temperature respectively. We show that it is beneficial to have\nsome hydrogen in the carrier gas mixture for GaSb growth to achieve good\ncrystal quality, morphology and electrical properties. Furthermore, an\nunexpected and previously unreported decomposition process of GaSb is observed\nat relatively low growth temperatures under the supply of the precursors for\nInAs epitaxial overgrowth. This nevertheless gets suppressed at even lower\ngrowth temperatures.",
        "positive": "Hydrogen-induced degradation dynamics in silicon heterojunction solar\n  cells via machine learning: Among silicon-based solar cells, heterojunction cells hold the world\nefficiency record. However, their market acceptance is hindered by an initial\n0.5\\% per year degradation of their open circuit voltage which doubles the\noverall cell degradation rate. Here, we study the performance degradation of\ncrystalline-Si/amorphous-Si:H heterojunction stacks. First, we experimentally\nmeasure the interface defect density over a year, the primary driver of the\ndegradation. Second, we develop SolDeg, a multiscale, hierarchical simulator to\nanalyze this degradation by combining Machine Learning, Molecular Dynamics,\nDensity Functional Theory, and Nudged Elastic Band methods with analytical\nmodeling. We discover that the chemical potential for mobile hydrogen develops\na gradient, forcing the hydrogen to drift from the interface, leaving behind\nrecombination-active defects. We find quantitative correspondence between the\ncalculated and experimentally determined defect generation dynamics. Finally,\nwe propose a reversed Si-density gradient architecture for the amorphous-Si:H\nlayer that promises to reduce the initial open circuit voltage degradation from\n0.5\\% per year to 0.1\\% per year."
    },
    {
        "anchor": "On the Crystallization of Terbium Aluminium Garnet: Attempts to grow terbium aluminium garnet (Tb3Al5O12, TAG) by the Czochralski\nmethod lead to crystals of millimeter scale. Larger crystals could not be\nobtained. DTA measurements within the binary system showed that TAG melts\nincongruently at 1840 deg. C. The perovskite (TbAlO3, TAP) with a congruent\nmelting point of 1930 deg. C is the most stable phase in this system. The\nregion for primary crystallization of TAP covers the chemical composition of\nTAG and suppresses the primary crystallization of the terbium aluminium garnet.",
        "positive": "Effect of material stiffness on hardness: a computational study based on\n  model potentials: We investigate the dependence of the hardness of materials on their elastic\nstiffness. This is possible by constructing a series of model potentials of the\nMorse type; starting on modelling natural Cu, the model potential exhibit an\nincreased elastic modulus, while keeping all other potential parameters\n(lattice constant, bond energy) unchanged. Using molecular-dynamics simulation,\nwe perform nanoindentation experiments on these model crystals. We find that\nthe crystal hardness scales with the elastic stiffness. Also the load drop,\nwhich is experienced when plasticity sets in, increases in proportion to the\nelastic stiffness, while the yield point, i.e., the indentation at which\nplasticity sets in, is independent of the elastic stiffness."
    },
    {
        "anchor": "Physical and Electrochemical Area Determination of Electrodeposited Ni,\n  Co, and NiCo Thin Films: The surface area of electrodeposited thin films of Ni, Co, and NiCo was\nevaluated using electrochemical double-layer capacitance, electrochemical area\nmeasurements using the [Ru(NH$_3$)$_6$]$^{3+}$/[Ru(NH$_3$)$_6$]$^{2+}$ redox\ncouple, and topographic atomic force microscopy (AFM) imaging. These three\nmethods were compared to each other for each composition separately and for the\nentire set of samples regardless of composition. Double-layer capacitance\nmeasurements were found to be positively correlated to the roughness factors\ndetermined by AFM topography. Electrochemical area measurements were found to\nbe less correlated with measured roughness factors as well as applicable only\nto two of the three compositions studied. The results indicate that in situ\ndouble-layer capacitance measurements are a practical, versatile technique for\nestimating the accessible surface area of a metal sample.",
        "positive": "Integration of the Ferromagnetic Insulator EuO onto Graphene: We have demonstrated the deposition of EuO films on graphene by reactive\nmolecular beam epitaxy in a special adsorption-controlled and oxygen-limited\nregime, which is a critical advance toward the realization of the exchange\nproximity interaction (EPI). It has been predicted that when the ferromagnetic\ninsulator (FMI) EuO is brought into contact with graphene, an overlap of\nelectronic wavefunctions at the FMI/graphene interface can induce a large spin\nsplitting inside the graphene. Experimental realization of this effect could\nlead to new routes for spin manipulation, which is a necessary requirement for\na functional spin transistor. Furthermore, EPI could lead to novel spintronic\nbehavior such as controllable magnetoresistance, gate tunable exchange bias,\nand quantized anomalous Hall effect. However, experimentally, EuO has not yet\nbeen integrated onto graphene. Here we report the successful growth of high\nquality crystalline EuO on highly-oriented pyrolytic graphite (HOPG) and\nsingle-layer graphene. The epitaxial EuO layers have (001) orientation and do\nnot induce an observable D peak (defect) in the Raman spectra. Magneto-optic\nmeasurements indicate ferromagnetism with Curie temperature of 69 K, which is\nthe value for bulk EuO. Transport measurements on exfoliated graphene before\nand after EuO deposition indicate only a slight decrease in mobility."
    },
    {
        "anchor": "Extreme Fermi surface smearing in a maximally disordered concentrated\n  solid solution: We show that the Fermi surface can survive the presence of extreme\ncompositional disorder in the equiatomic alloy\nNi$_{0.25}$Fe$_{0.25}$Co$_{0.25}$Cr$_{0.25}$. Our high-resolution Compton\nscattering experiments reveal a Fermi surface which is smeared across a\nsignificant fraction of the Brillouin zone (up to 40\\% of $\\frac{2\\pi}{a}$).\nThe extent of this smearing and its variation on and between different sheets\nof the Fermi surface has been determined, and estimates of the electron\nmean-free-path and residual resistivity have been made by connecting this\nsmearing with the coherence length of the quasiparticle states.",
        "positive": "On the threshold of ion track formation in CaF2: There is ongoing debate regarding the mechanism of swift heavy ion track\nformation in CaF2. The objective of this study is to shed light on this\nimportant topic using a range of complimentary experimental techniques.\nEvidence of the threshold for ion track formation being below 3 keV/nm is\nprovided by both transmission electron microscopy and Rutherford backscattering\nspectroscopy in the channeling mode which has direct consequences for the\nvalidity of models describing the response of CaF2 to swift heavy ion\nirradiation. Advances in the TEM and RBS/c analyses presented here pave the way\nfor better understanding of the ion track formation."
    },
    {
        "anchor": "Exchange spin waves in thin films with gradient composition: We report investigation of ferromagnetic resonance phenomenon in\nferromagnetic thin films with essentially non-uniform composition. Epitaxial\nPd-Fe thin film with linear distribution of Fe content across the thickness is\nused as the model material. Anomalous perpendicular standing spin waves are\nobserved and quantified using the collective dynamic equation. Numerical\nanalysis yields the exchange stiffness constant for diluted Pd-Fe alloy\n$D=2A/\\mu_0M_s=15$~T$\\cdot$nm$^2$ and the ratio of the effective magnetization\nto the saturation magnetization $M_{eff}/M_s=1.16$. It is demonstrated that,\noverall, engineering of thin films with non-uniform composition across the\nthickness can be used for high-frequency or low-field magnonic operations using\nexchange spin waves.",
        "positive": "Extreme thermopower anisotropy and interchain transport in the\n  quasi-one-dimensional metal Li(0.9)Mo(6)O(17): Thermopower and electrical resistivity measurements transverse to the\nconducting chains of the quasi-one-dimensional metal Li(0.9)Mo(6)O(17) are\nreported in the temperature range 5 K <= T <= 500 K. For T>= 400 K the\ninterchain transport is determined by thermal excitation of charge carriers\nfrom a valence band ~ 0.14 eV below the Fermi level, giving rise to a large,\np-type thermopower that coincides with a small, n-type thermopower along the\nchains. This dichotomy -- semiconductor-like in one direction and metallic in a\nmutually perpendicular direction -- gives rise to substantial transverse\nthermoelectric (TE) effects and a transverse TE figure of merit among the\nlargest known for a single compound."
    },
    {
        "anchor": "Structural Characterization of Grain Boundaries and Machine Learning of\n  Grain Boundary Energy and Mobility: Recent advances in the numerical representation of materials opened the way\nfor successful machine learning of grain boundary (GB) energies and the\nclassification of GB mobility and shear coupling. Two representations were\nneeded for these machine learning applications: 1) the ASR representation,\nbased on averaged local environment descriptors; and 2) the LER descriptor,\nbased on fractions of globally unique local environments within the entire GB\nsystem. We present a detailed tutorial on how to construct these two\nrepresentations to learn energy, mobility and shear coupling. Additionally, we\ncatalog some of the null results encountered along the way.",
        "positive": "Wave propagation through alumina-porous alumina laminates: A Brazilian disk geometry of an alumina layered composite with alternating\ndense and porous layers was dynamically loaded using a Split-Hopkinson Pressure\nBar (SHPB)apparatus under compression. High-speed imaging and transmitted force\nmeasurements were used to gain an insight into stress wave propagation and\nmitigation through such a layered system. Uniformly distributed porosities of\n20 and 50 vol % were introduced into the interlayers by the addition of fine\ngraphite particles which volatilized during heat treatment. Brazilian disk\nsamples were cut from the cylinders which were drilled out of the sintered\nlaminated sample. The disks were subjected to dynamic impact loading in\nperpendicular and parallel orientations to the layers in order to investigate\nthe influence of the direction of impact. The dynamic failure process of the\nlayered ceramic consisted of the initiation and propagation of the cracks\nmainly along the interphases of the layers. Upon impact, the impact energy was\ndissipated through fracture in parallel orientation (0 deg) but transmitted in\nperpendicular (90 deg) orientations. The high degree of correlation between the\ntransmitted force, microstructure and orientation in which the layered systems\nwere impacted is discussed."
    },
    {
        "anchor": "Aperiodic Tilings on the Computer: We briefly review the standard methods used to construct quasiperiodic\ntilings, such as the projection, the inflation, and the grid method. A number\nof sample Mathematica programs, implementing the different approaches for one-\nand two-dimensional examples, are discussed. Apart from small examples, the\ncorresponding programs are not contained in the text, but will be made\navailable in electronic form.",
        "positive": "Effect of Oxygen on Hydrogen Diffusivity in hcp-Zirconium: Zirconium and its alloys are extensively used as cladding material in nuclear\nreactors. They are vulnerable to hydrogen degradation under the harsh service\nconditions of the reactors, which necessitates continuous monitoring for the\nhydride concentration. The presence of hydride denuded zones in the latter\nstages of the pressure tube's life hinders the monitoring process, which is\ncarried out by scrape samples taken from the surface of pressure tubes. We\ninvestigated the effect of oxygen on diffusivity of hydrogen in hcp-Zr, to\ncheck the hypothesis that oxygen slows the diffusion of hydrogen and thereby\nencourages the occurrence of hydride denuded zones. From the study we found\nthat oxygen indeed decreases the diffusivity of hydrogen in hcp-Zr for moderate\nO concentrations, supporting the hypothesis. We investigated the diffusion\nprocesses of individual H atoms, which showed that the reduction in diffusivity\nis caused by a decrease in the hopping rates and the formation of hydrogen\ntraps by the combination of several interstitial sites."
    },
    {
        "anchor": "Hydrodynamic approach to surface pattern formation by ion beams: On the proper timescale, amorphous solids can flow. Solid flow can be\nobserved macroscopically in glaciers or lead pipes, but it can also be\nartificially enhanced by creating defects. Ion Beam Sputtering (IBS) is a\ntechnique in which ions with energies in the 0.1-10 keV range impact against a\nsolid target inducing defect creation and dynamics, and eroding its surface\nleading to formation of ordered nanostructures. Despite its technological\ninterest, a basic understanding of nanopattern formation processes occurring\nunder IBS of amorphizable targets has not been clearly established, recent\nexperiments on Si having largely questioned knowledge accumulated during the\nlast two decades. A number of interfacial equations have been proposed in the\npast to describe these phenomena, typically by adding together different\ncontributions coming from surface diffusion, ion sputtering or mass\nredistribution, etc. in a non-systematic way. Here, we exploit the general idea\nof solids flowing due to ion impacts in order to establish a general framework\ninto which different mechanisms (such as viscous flow, stress, diffusion, or\nsputtering) can be incorporated, under generic physical conservation laws. As\nopposed to formulating phenomenological interfacial equations, this approach\nallows to assess systematically the relevance and interplay of different\nphysical mechanisms influencing surface pattern formation by IBS.",
        "positive": "Vibration analysis of a pre-stressed graphene sheet embedded in a\n  deformable matrix: The effect of the initial uniaxial stress and a surrounding elastic matrix on\nthe transverse vibration response of a single-layered graphene sheet (SLGS) is\ninvestigated through a theoretical formulation that is based on the nonlocal\nKirchhoff plate theory. The surrounding elastic matrix of the SLGS is modeled\nas a foundation of the Pasternak-type. The elliptic partial differential\nequation governing the dynamics of the pre-stressed SLGS is solved with the\nRayleigh method. Numerical results from the analyses reveal different level of\nsensitivity of the vibration response of the SLGS to changes in the control\nparameters of the model. Pareto charts of the effect of the control parameters\nin the mathematical model show the shear modulus of the foundation to have the\nmost dominant influence on the fundamental natural frequency of the SLGS. The\nsmall-scale effect is found to have more pronounced effect on the vibration\nresponse of the SLGS when it is fully clamped at the four edges."
    },
    {
        "anchor": "Spin filtering in CrI$_3$ tunnel junctions: The recently discovered magnetism of two-dimensional (2D) van der Waals\ncrystals have attracted a lot of attention. Among these materials is CrI$_3$ -\na magnetic semiconductor exhibiting transitions between antiferromagnetic and\nferromagnetic orderings under the influence of an applied magnetic field. Here,\nusing first-principles methods based on density functional theory, we explore\nspin-dependent transport in tunnel junctions formed of fcc Cu (111) electrodes\nand a CrI$_3$ tunnel barrier. We find about 100% spin polarization of the\ntunneling current for a ferromagnetically-ordered four-monolayer CrI$_3$ and\ntunneling magnetoresistance of about 3,000% associated with a change of\nmagnetic ordering in CrI$_3$. This behavior is understood in terms of the spin\nand wave-vector dependent evanescent states in CrI$_3$ which control the\ntunneling conductance. We find a sizable charge transfer from Cu to CrI$_3$\nwhich adds new features to the mechanism of spin-filtering in CrI$_3$-based\ntunnel junctions. Our results elucidate the mechanisms of spin filtering in\nCrI3 tunnel junctions and provide important insights for the design of\nmagnetoresistive devices based on 2D magnetic crystals.",
        "positive": "Adaptive Programming of Unconventional Nano-Architectures: Novel assembly processes for nanocircuits could present compelling\nalternatives to the detailed design and placement currently used for computers.\nThe resulting architectures however may not be programmable by standard means.\nIn this paper, nanocomputers with unconventional architectures are programmed\nusing adaptive methods. The internals of the device are treated as a \"black\nbox\" and programming is achieved by manipulating \"control voltages\". Learning\nalgorithms are used to set the controls. As examples, logic gates and simple\narithmetic circuits are implemented. Additionally, similar methods allow for\nreconfiguration of the devices, and makes them resistant to certain kinds of\nfaults."
    },
    {
        "anchor": "Disruption of the accidental Dirac semimetal state in ZrTe$_{5}$ under\n  hydrostatic pressure: We study the effect of hydrostatic pressure on the magnetotransport\nproperties of the zirconium pentatelluride. The magnitude of resistivity\nanomaly gets enhanced with increasing pressure, but the transition temperature\n$T^{\\ast}$ is almost independent of it. In the case of H $\\parallel$ $b$, the\nquasi-linear magnetoresistance decreases drastically from 3300$\\%$ (9 T) at\nambient pressure to 400$\\%$ (14 T) at 2.5 GPa. Besides, the change of the\nquantum oscillation phase from topological nontrivial to trivial is revealed\naround 2 GPa. Both demonstrate that the pressure breaks the accidental Dirac\nnode in ZrTe$_{5}$. For H $\\parallel$ $c$, in contrast, subtle changes can be\nseen in the magnetoresistance and quantum oscillations. In the presence of\npressure, ZrTe$_{5}$ evolves from a highly anisotropic to a nearly isotropic\nelectronic system, which accompanies with the disruption of the accidental\nDirac semimetal state. It supports the assumption that ZrTe$_{5}$ is a semi-3D\nDirac system with linear dispersion along two directions and a quadratic one\nalong the third.",
        "positive": "Gallium concentration dependence of room-temperature near-bandedge\n  luminescence in n-type ZnO:Ga: We investigated the optical properties of epitaxial \\textit{n}-type ZnO films\ngrown on lattice-matched ScAlMgO$_4$ substrates. As the Ga doping concentration\nincreased up to $6 \\times 10^{20}$ cm$^{-3}$, the absorption edge showed a\nsystematic blueshift, consistent with the Burstein-Moss effect. A bright\nnear-bandedge photoluminescence (PL) could be observed even at room\ntemperature, the intensity of which increased monotonically as the doping\nconcentration was increased except for the highest doping level. It indicates\nthat nonradiative transitions dominate at a low doping density. Both a Stokes\nshift and broadening in the PL band are monotonically increasing functions of\ndonor concentration, which was explained in terms of potential fluctuations\ncaused by the random distribution of donor impurities."
    },
    {
        "anchor": "Crossover from Kondo assisted suppression to co-tunneling enhancement of\n  tunneling magnetoresistance via ferromagnetic nanodots in MgO tunnel barriers: Recently, it has been shown that magnetic tunnel junctions with thin MgO\ntunnel barriers exhibit extraordinarily high tunneling magnetoresistance (TMR)\nvalues at room temperature1, 2. However, the physics of spin dependent\ntunneling through MgO barriers is only beginning to be unravelled. Using planar\nmagnetic tunnel junctions in which ultra-thin layers of magnetic metals are\ndeposited in the middle of a MgO tunnel barrier here we demonstrate that the\nTMR is strongly modified when these layers are discontinuous and composed of\nsmall pancake shaped nanodots. At low temperatures, in the Coulomb blockade\nregime, for layers less than ~1 nm thick, the conductance of the junction is\nincreased at low bias consistent with Kondo assisted tunneling. In the same\nregime we observe a suppression of the TMR. For slightly thicker layers, and\ncorrespondingly larger nanodots, the TMR is enhanced at low bias, consistent\nwith co-tunneling.",
        "positive": "Hybrid functional analysis of porous coordination polymers\n  Cu[Cu(pdt)$_{2}$] and Cu[Ni(pdt)$_{2}$]: Ab initio investigation of the two porous coordination polymers Cu[Cu(pdt)$\n_{2} $] and Cu[Ni(pdt)$ _{2} $] has been performed. The dispersion laws and\npartial density of states was obtained with the PBE0 hybrid functional. The\nresults found here show that the materials under consideration are degenerate\n$p$-type semiconductors. Here, the effect of partial self-interaction removing\nof the strongly correlated 3$d$ electrons of Cu and Ni was examined. In case of\nCu-containing materials, the obtained results confirm that the 3$d$ electrons\nof Cu reveal strong correlations, and, therefore, their electronic properties\ncould be evaluated by means of a hybrid functional of the exchange-correlation\nenergy. We also obtained quasiparticle properties within the Green's function\n(G0W0) and Bethe-Salpeter approaches. The last one was used in order to examine\nexcitonic properties in the degenerate semiconductors. The imaginary part of\nthe dielectric function was obtained within random-phase approximation as well\nas the Bethe-Salpeter approach."
    },
    {
        "anchor": "Flexoelectric and piezoelectric coupling in a bended MoS$_2$ monolayer: Low-dimensional (LD) transition metal dichalcogenides (TMDs) in the form of\nnanoflakes, which consist of one or several layers, are the subject of\nintensive fundamental and applied research. Due to the size-induced transition\nfrom a bulk to nanoscale, they can be both nonpolar, piezoelectric or even\nferroelectric. Also, in terms of electronic properties, they can be direct-band\nsemiconductors, semi-metals or even metals. The tuning of the electronic\nproperties in the LD-TMDs are commonly related with applied strains and strain\ngradients, which can affect strongly their polar properties via the\npiezoelectric and flexoelectric couplings. Using the density functional theory\n(DFT) and phenomenological Landau approach, we studied the bended 2H-MoS$_2$\nmonolayer and analyzed its flexoelectric and piezoelectric properties. The\ndependences of the dipole moment, strain and strain gradient on the coordinate\nalong the layer were calculated. From these dependences the components of the\nflexoelectric and piezoelectric tensors have been determined and analyzed.\nObtained results are useful for applications of LD-TMDs in strain engineering\nand flexible electronics.",
        "positive": "Elastic domains in antiferromagnets: We consider periodic domain structures which appear due to the magnetoelastic\ninteraction if the antiferromagnetic crystal is attached to an elastic\nsubstrate. The peculiar behavior of such structures in an external magnetic\nfield is discussed. In particular, we find the magnetic field dependence of the\nequilibrium period and the concentrations of different domains."
    },
    {
        "anchor": "Quantifying the magnetic interactions governing chiral spin textures\n  using deep neural networks: The interplay of magnetic interactions in chiral multilayer films gives rise\nto nanoscale topological spin textures, which form attractive elements for\nnext-generation computing. Quantifying these interactions requires several\nspecialized, time-consuming, and resource-intensive experimental techniques.\nImaging of ambient domain configurations presents a promising avenue for\nhigh-throughput extraction of the parent magnetic interactions. Here we present\na machine learning-based approach to determine the key interactions --\nsymmetric exchange, chiral exchange, and anisotropy -- governing chiral domain\nphenomenology in multilayers. Our convolutional neural network model, trained\nand validated on over 10,000 domain images, achieved $R^2 > 0.85$ in predicting\nthe parameters and independently learned physical interdependencies between\nthem. When applied to microscopy data acquired across samples, our\nmodel-predicted parameter trends are consistent with independent experimental\nmeasurements. These results establish ML-driven techniques as valuable,\nhigh-throughput complements to conventional determination of magnetic\ninteractions, and serve to accelerate materials and device development for\nnanoscale electronics.",
        "positive": "Footprints in Sand: The Response of a Granular Material to Local\n  Perturbations: We experimentally determine ensemble-averaged responses of granular packings\nto point forces, and we compare these results to recent models for force\npropagation in a granular material. We used 2D granular arrays consisting of\nphotoelastic particles: either disks or pentagons, thus spanning the range from\nordered to disordered packings. A key finding is that spatial ordering of the\nparticles is a key factor in the force response. Ordered packings have a\npropagative component that does not occur in disordered packings."
    },
    {
        "anchor": "Bandgap measurement of high refractive index materials by off-axis EELS: In the present work, Cs aberration corrected and monochromated scanning\ntransmission electron microscopy electron energy loss spectroscopy STEM-EELS\nhas been used to explore experimental set-ups that allows bandgaps of high\nrefractive index materials to be determined. Semi-convergence and -collection\nangles in the micro-radian range were combined with off-axis or dark field EELS\nto avoid relativistic losses and guided light modes in the low loss range to\ncontribute to the acquired EEL spectra. Off-axis EELS further suppressed the\nzero loss peak and the tail of the zero loss peak. The bandgap of several\nGaAs-based materials were successfully determined by direct inspection and\nwithout any background subtraction of the EEL spectra. The presented set-up\ndoes not require that the acceleration voltage is set to below the Cerenkov\nlimit and can be applied over the entire acceleration voltage range of modern\nTEMs and for a wide range of specimen thicknesses.",
        "positive": "Spin resonance of 2D electrons in a large-area silicon MOSFET: We report electron spin resonance (ESR) measurements on a large-area silicon\nMOSFET. An ESR signal at g-factor 1.9999(1), and with a linewidth of 0.6 G, is\nobserved and found to arise from two-dimensional (2D) electrons at the Si/SiO2\ninterface. The signal and its intensity show a pronounced dependence on applied\ngate voltage. At gate voltages below the threshold of the MOSFET, the signal is\nfrom weakly confined, isolated electrons as evidenced by the Curie-like\ntemperature dependence of its intensity. The situation above threshold appears\nmore complicated. These large-area MOSFETs provide the capability to\ncontrollably tune from insulating to conducting regimes by adjusting the gate\nvoltage while monitoring the state of the 2D electron spins spectroscopically."
    },
    {
        "anchor": "Two-dimensional modeling of the self-limiting oxidation in silicon and\n  tungsten nanowires: Self-limiting oxidation of nanowires has been previously described as a\nreaction- or diffusion-controlled process. In this letter, the concept of\nfinite reactive region is introduced into a diffusion-controlled model, based\nupon which a two-dimensional cylindrical kinetics model is developed for the\noxidation of silicon nanowires and is extended for tungsten. In the model,\ndiffusivity is affected by the expansive oxidation reaction induced stress. The\ndependency of the oxidation upon curvature and temperature is modeled. Good\nagreement between the model predictions and available experimental data is\nobtained. The developed model serves to quantify the oxidation in\ntwo-dimensional nanostructures and is expected to facilitate their fabrication\nvia thermal oxidation techniques. https://doi.org/10.1016/j.taml.2016.08.002",
        "positive": "Tunable energy transfer between dipolar-coupled magnetic disks by\n  stimulated vortex gyration: A wide variety of coupled harmonic oscillators exist in nature1. Coupling\nbetween different oscillators allows for the possibility of mutual energy\ntransfer between them2-4 and the information-signal propagation5,6. Low-energy\ninput signals and their transport with low-energy dissipation are the key\ntechnical factors in the design of information processing devices7. Here,\nutilizing the concept of coupled oscillators, we experimentally demonstrated a\nrobust new mechanism for energy transfer between spatially separated\ndipolar-coupled magnetic disks - stimulated vortex gyration. Direct\nexperimental evidence was obtained by time-resolved soft X-ray microscopy. The\nrate of energy transfer from one disk to the other was deduced from the two\nnormal modes' frequency splitting caused by dipolar interaction. This mechanism\nprovides the advantages of tunable energy transfer rate, low-power input\nsignal, and low-energy dissipation for magnetic elements with negligible\ndamping. Coupled vortex-state disks are promising candidates for\ninformation-signal processing devices that operate above room temperature."
    },
    {
        "anchor": "Dynamics of diluted magnetic semiconductors from atomistic spin dynamics\n  simulations: Mn doped GaAs as a case study: The dynamical behavior of the magnetism of diluted magnetic semiconductors\n(DMS) has been investigated by means of atomistic spin dynamics simulations.\nThe conclusions drawn from the study are argued to be general for DMS systems\nin the low concentration limit, although all simulations are done for 5%\nMn-doped GaAs with various concentrations of As antisite defects. The\nmagnetization curve, $M(T)$, and the Curie temperature $T_C$ have been\ncalculated, and are found to be in good correspondence to results from Monte\nCarlo simulations and experiments. Furthermore, equilibrium and non-equilibrium\nbehavior of the magnetic pair correlation function have been extracted. The\ndynamics of DMS systems reveals a substantial short ranged magnetic order even\nat temperatures at or above the ordering temperature, with a non-vanishing pair\ncorrelation function extending up to several atomic shells. For the high As\nantisite concentrations the simulations show a short ranged anti-ferromagnetic\ncoupling, and a weakened long ranged ferromagnetic coupling. For sufficiently\nlarge concentrations we do not observe any long ranged ferromagnetic\ncorrelation. A typical dynamical response shows that starting from a random\norientation of moments, the spin-correlation develops very fast ($\\sim$ 1ps)\nextending up to 15 atomic shells. Above $\\sim$ 10 ps in the simulations, the\npair correlation is observed to extend over some 40 atomic shells. The\nautocorrelation function has been calculated and compared with ferromagnets\nlike bcc Fe and spin-glass materials. We find no evidence in our simulations\nfor a spin-glass behaviour, for any concentration of As antisites. Instead the\nmagnetic response is better described as slow dynamics, at least when compared\nto that of a regular ferromagnet like bcc Fe.",
        "positive": "Graphane Nanoribbons: A Theoretical Study: In this study, we investigate the electronic and magnetic properties of\ngraphane nanoribbons. We find that zigzag and armchair graphane nanoribbons\nwith H-passivated edges are nonmagnetic semiconductors. While bare armchair\nribbons are also nonmagnetic, adjacent dangling bonds of bare zigzag ribbons\nhave antiferromagnetic ordering at the same edge. Band gaps of the H-passivated\nzigzag and armchair nanoribbons exponentially depend on their width. Detailed\nanalysis of adsorption of C, O, Si, Pt, Ti, V and Fe atoms on the graphane\nribbon surface reveal that functionalization of graphane ribbons is possible\nvia these adatoms. It is found that C, O, V and Pt atoms have tendency to\nreplace H atoms of graphane. We showed that significant spin polarizations in\ngraphane can be achieved through creation of domains of H-vacancies and\nCH-divacancies."
    },
    {
        "anchor": "Tutorial: A Beginner's Guide to Interpreting Magnetic Susceptibility\n  Data with the Curie-Weiss Law: Magnetic susceptibility measurements are often the first characterization\ntool that researchers turn to when beginning to assess the magnetic nature of a\nnewly discovered material. Breakthroughs in instrumentation have made the\ncollection of high quality magnetic susceptibility data more accessible than\never before. However, the analysis of susceptibility data remains a common\nchallenge for newcomers to the field of magnetism. While a comprehensive\ntreatment of the theoretical aspects of magnetism are found in numerous\nexcellent textbooks, there is a gap at the point of practical application. We\nwere inspired by this obstacle to put together this guide to the analysis and\ninterpretation of magnetic susceptibility data, with an emphasis on materials\nthat exhibit Curie-Weiss paramagnetism.",
        "positive": "Elastic moduli of model random three-dimensional closed-cell cellular\n  solids: Most cellular solids are random materials, while practically all theoretical\nresults are for periodic models. To be able to generate theoretical results for\nrandom models, the finite element method (FEM) was used to study the elastic\nproperties of solids with a closed-cell cellular structure. We have computed\nthe density ($\\rho$) and microstructure dependence of the Young's modulus ($E$)\nand Poisson's ratio (PR) for several different isotropic random models based on\nVoronoi tessellations and level-cut Gaussian random fields. The effect of\npartially open cells is also considered. The results, which are best described\nby a power law $E\\propto\\rho^n$ ($1 < n <2$), show the influence of randomness\nand isotropy on the properties of closed-cell cellular materials, and are found\nto be in good agreement with experimental data."
    },
    {
        "anchor": "Electronic and magnetic properties of epitaxial thin film of\n  Nd\\tsubscript{0.5}Ba\\tsuscriptb{0.5}MnO\\tsubscript{3}: Contradictory reports about the electronic and magnetic behavior of bulk\nNd0:5Ba0:5MnO3 with uniform disorder exist in the literature. In this work, we\ninvestigate the thin films of Nd0:5Ba0:5MnO3, grown by pulsed laser deposition.\nThe success of epitaxial growth in a layer-by-layer mode and high quality of\nthe films have been confirmed by in-situ reflection high energy electron\ndiffraction, atomic force microscopy, X-ray reflectivity, and, X-ray\ndiffraction. These films are found to be insulting and exhibit spin-glass\nbehavior at low temperatures. The study offers an opportunity to tune the\ncompetition between charge/orbital ordering and ferromagnetism in half-doped\nmanganites through heterostructure engineering.",
        "positive": "Interfacial Coupling in Multiferroic-Ferromagnet Heterostructures: We report local probe investigations of the magnetic interaction between\nBiFeO3 films and a ferromagnetic Co0.9Fe0.1 layer. Within the constraints of\nintralayer exchange coupling in the Co0.9Fe0.1, the multiferroic imprint in the\nferromagnet results in a collinear arrangement of the local magnetization and\nthe in-plane BiFeO3 ferroelectric polarization. The magnetic anisotropy is\nuniaxial, and an in-plane effective coupling field of order 10 mT is derived.\nMeasurements as a function of multiferroic layer thickness show that the\ninfluence of the multiferroic layer on the magnetic layer becomes negligible\nfor 3 nm thick BiFeO3 films. We ascribe this breakdown in the exchange coupling\nto a weakening of the antiferromagnetic order in the ultrathin BiFeO3 film\nbased on our X-ray linear dichroism measurements. These observations are\nconsistent with an interfacial exchange coupling between the CoFe moments and a\ncanted antiferromagnetic moment in the BiFeO3."
    },
    {
        "anchor": "Non-equilibrium heating path for utrafast laser-induced nucleation of\n  skyrmion lattices: We explore the helicity-independent light-induced nucleation of skyrmion\nlattices in ferromagnetic cobalt-based trilayers with perpendicular magnetic\nanisotropy. Using Atomistic Spin Dynamics simulations, we show that a high\ntemperature excitation followed by magnon drops and their non-equilibrium\nrelaxation, accessed by an ultrafast laser excitation with specific duration\nand intensity, can lead to the generation of a skyrmion lattice stable at room\ntemperature. The nucleation window, the topological density and the skyrmion\npolarity can be additionally manipulated by external magnetic fields. Our\nresults provide insight into the non-equilibrium nature of skyrmionic\nexcitations at non-zero temperatures and pave additional routes for their use\nin information technologies.",
        "positive": "Viscosity and Structure Configuration Properties of Equilibrium and\n  Supercooled Liquid Cobalt: The shear viscosity of liquid cobalt at the pressure $p=1.5$~bar and at the\ntemperatures corresponding to equilibrium liquid and supercooled liquid states\nis measured experimentally and evaluated by means of molecular dynamics\nsimulations. Further, the shear viscosity is also calculated within the\nmicroscopic theoretical model. Comparison of our experimental, simulation and\ntheoretical results with other available data allows one to examine the issue\nabout the correct temperature dependence of the shear viscosity of liquid\ncobalt. It is found a strong correlation between the viscosity and the\nconfiguration entropy of liquid cobalt over the considered temperature range,\nwhich can be taken into account by the Rosenfeld's model."
    },
    {
        "anchor": "Intrinsic bending flexoelectric constants in two-dimensional materials: Flexoelectricity is a form of electromechanical coupling that has recently\nemerged because, unlike piezoelectricity, it is theoretically possible in any\ndielectric material. Two-dimensional (2D) materials have also garnered\nsignificant interest because of their unusual electromechanical properties and\nhigh flexibility, but the intrinsic flexoelectric properties of these materials\nremain unresolved. In this work, using atomistic modeling accounting for\ncharge-dipole interactions, we report the intrinsic flexoelectric constants for\na range of two-dimensional materials, including graphene allotropes, nitrides,\ngraphene analogs of group-IV elements, and the transition metal dichalcogenides\n(TMDCs). We accomplish this through a proposed mechanical bending scheme that\neliminates the piezoelectric contribution to the total polarization, which\nenables us to directly measure the flexoelectric constants. While flat 2D\nmaterials like graphene have low flexoelectric constants due to weak\n$\\pi-\\sigma$ interactions, buckling is found to increase the flexoelectric\nconstants in monolayer group-IV elements. Finally, due to significantly\nenhanced charge transfer coupled with structural asymmetry due to bending, the\nTMDCs are found to have the largest flexoelectric constants, including\nMoS$_{2}$ having a flexoelectric constant ten times larger than graphene.",
        "positive": "Doublon Growth in Solidification: We present experiments on the doublon growth morphology in directional\nsolidification. Samples used are succinonitrile with small amounts of\npoly(ethylene oxide), acetone, or camphor as the solute. Doublons, or\nsymmetry-broken dendrites, are generic diffusion-limited growth structures\nexpected at large undercooling and low anisotropy. Low anisotropy growth is\nachieved by selecting a grain near the $\\{111\\}$ plane leading to either\nseaweed (dense branching morphology) or doublon growth depending on\nexperimental parameters. We find selection of doublons to be strongly dependent\non solute concentration and sample orientation. Doublons are selected at low\nconcentrations (low solutal undercooling) in contrast to the prediction of\ndoublons at large thermal undercooling in pure materials. Doublons also exhibit\npreferred growth directions and changing the orientation of a specific\ndoublonic grain changes the character and stability of the doublons. We observe\ntransitions between seaweed and doublon growth with changes in concentration\nand sample orientation."
    },
    {
        "anchor": "Visualization of Dynamic Polaronic Strain Fields in Hybrid Lead Halide\n  Perovskites: Excitation localization involving dynamic nanoscale distortions is a central\naspect of photocatalysis, quantum materials and molecular optoelectronics.\nExperimental characterization of such distortions requires techniques sensitive\nto the formation of point-defect-like local structural rearrangements in real\ntime. Here, we visualize excitation-induced strain fields in a prototypical\nmember of the lead halide perovskites via femtosecond resolution diffuse x-ray\nscattering measurements. This enables momentum-resolved phonon spectroscopy of\nthe locally-distorted structure and reveals radially-expanding nanometer-scale\nelastic strain fields associated with the formation and relaxation of polarons\nin photoexcited perovskites. Quantitative estimates of the magnitude and the\nshape of this polaronic distortion are obtained, providing direct insights into\nthe debated dynamic structural distortions in these materials. Optical\npump-probe reflection spectroscopy corroborates these results and shows how\nthese large polaronic distortions transiently modify the carrier effective\nmass, providing a unified picture of the coupled structural and electronic\ndynamics that underlie the unique optoelectronic functionality of the hybrid\nperovskites.",
        "positive": "On-Surface Synthesis of a Pure and Long-Range-Ordered\n  Titanium(IV)-Porphyrin Contact Layer on Titanium Dioxide: We show the possibility of tailoring the molecular arrangement, as well as\nthe chemical and structural modifications, of porphyrins at the monolayer\nsaturation coverage on TiO2(110) by Synchrotron photoemission, electron\ndiffraction, STM topography and DFT calculations. Free-base\ntetra-phenyl-porphyrins (2H-TPP) adsorb on the oxygen rows, where they can\nspontaneously capture two additional hydrogen atoms at their iminic nitrogens\n(4H-TPP). Both 2H-TPP and 4H-TPP molecules aggregate into a commensurate phase\nat the saturation coverage of one monolayer. Upon sample heating, a\nself-metalation reaction sets in at 100C, yielding full metalation of the\nsaturated monolayer at ~200C. The Ti atoms are extracted from the substrate\nand, by simultaneous dehydrogenation of the pyrrolic nitrogen atoms,\nincorporated into the porphyrin macrocycle, where they remain coordinated to\ntwo oxygen atoms underneath. Neither the adsorption geometry (on-bridge, atop\nthe oxygen rows) nor the molecular arrangement change across the\nself-metalation transition up to 300C. On one side, the robustness of this\nsaturation phase makes it a promising system for its implementation into\napplications for photocatalysis and photovoltaic devices. On the other side,\nthe possible manifestation of metal exchange with the very reactive Ti atoms\nmust be taken into account when designing porphyrin-sensitized solar cells\nsince the critical temperature for the onset of self-metalation is very close\nto the normal operating temperature of photovoltaic devices."
    },
    {
        "anchor": "Effects of Cation Vacancy Distribution in Doped LaMnO3+d Perovskites: In this paper we report studies on the correlation between the presence and\ndistribution of cation vacancies in doped manganites (La,M)MnO3+delta (where M\n= Na, Ca) and their magnetic properties. Results indicate that cation vacancies\nare distributed differently for the different crystal structures and dopant ion\ntype. In particular it is shown that knowledge of the total vacancies\nconcentration alone is not enough to fully characterize the physical properties\nof manganites and that their distribution between the A and B sites of the\nperovskite structure plays a crucial role which should be taken into account in\nfuture studies.",
        "positive": "Dzyaloshinskii-Moriya interaction at disordered interfaces from ab\n  initio theory: robustness against intermixing and tunability through dusting: The Dzyaloshinskii-Moriya interaction (DMI), which is essential for the\nstabilization of topologically non-trivial chiral magnetic textures such as\nskyrmions, is particularly strong in heterostructures of ultra-thin magnetic\nmaterials and heavy elements. We explore by density-functional theory\ncalculations the possibility to modify the magnetic properties at Co/Pt\ninterfaces with chemical disorder. In these systems, we find a particular\nrobustness of the DMI against intermixing. Upon dusting the interface with a\nthird element (all $4d$ transition metals and B, Cu, Au and Bi), a strong\nreduction of the DMI is predicted. This opens up possibilities to tune the DMI\nthrough the degrees of intermixing and dusting."
    },
    {
        "anchor": "Exploration of all-3d Heusler alloys for permanent magnets: an ab initio\n  based high-throughput study: Heusler alloys have attracted interest in various fields of functional\nmaterials since their properties can quite easily be tuned by composition.\nHere, we have investigated the relatively new class of all-3d Heusler alloys in\nview of its potential as permanent magnets. To identify suitable candidates, we\nperformed a high-throughput study using an electronic structure database to\nsearch for X$_2$YZ-type Heusler systems with tetragonal symmetry and high\nmagnetization. For the alloys which passed our selection filters, we have used\na combination of density functional theory calculations and spin dynamics\nmodelling to investigate their magnetic properties including the\nmagnetocrystalline anisotropy energy and exchange interactions. The candidates\nwhich fulfilled all the search criteria served as input for the investigation\nof the temperature dependence of the magnetization and determination of Curie\ntemperature. Based on our results, we suggest that Fe$_2$NiZn, Fe$_2$NiTi and\nNi$_2$CoFe are potential candidates for permanent magnets with large\nout-of-plane magnetic anisotropy (1.23, 0.97 and 0.82 MJ/m$^3$ respectively)\nand high Curie temperatures lying more than 200 K above the room temperature.\nWe further show that the magnitude and direction of anisotropy is very\nsensitive to the strain by calculating the values of anisotropy energy for\nseveral tetragonal phases. Thus, application of strain can be used to tune the\nanisotropy in these compounds.",
        "positive": "Highly sensitive magnetic properties and large linear magnetoresistance\n  in antiferromagnetic CrxSe(0.875\\lex\\le1)single crystals: CrxSe (x\\le1) is a class of quasi-layered binary compounds with potential\napplications in spintronics due to its intriguing antiferromagnetic properties.\nIn this work, CrxSe single crystals with high Cr content (x=0.87, 0.91 and\n0.95) were grown, and their magnetic and transport properties were investigated\nin detail. It is found that with small increase of Cr content, the N\\'eel\ntemperature (TN) of the samples can dramatically increase from 147 K to 257 K,\naccompanied with obvious changes in the magnetic anisotropy and hysteresis. The\nphenomena of field-induced spin-flop transitions were unveiled in these alloys,\nindicating their comparatively low anisotropy. The magnetoresistance (MR) of\nthe three compounds showed positive dependence at low temperatures and\nparticularly, non-saturated linear positive MR was observed in Cr0.91Se and\nCr0.95Se, with a large value of 16.2% achieved in Cr0.91Se (10K, 9T). The\ncalculated Fermi surface and MR showed that the quasi-linear MR is a product of\ncarrier compensation. Our work revealed highly sensitive magnetic and transport\nproperties in the Cr-Se compounds, which can lay foundation when constructing\nfurther antiferromagnetic spintronic devices based on them."
    },
    {
        "anchor": "Highly-flexible wide angle of incidence terahertz metamaterial absorber: We present the design, fabrication, and characterization of a metamaterial\nabsorber which is resonant at terahertz frequencies. We experimentally\ndemonstrate an absorptivity of 0.97 at 1.6 terahertz. Importantly, this\nfree-standing absorber is only 16 microns thick resulting in a highly flexible\nmaterial that, further, operates over a wide range of angles of incidence for\nboth transverse electric and transverse magnetic radiation.",
        "positive": "Electric-field-driven domain wall dynamics in perpendicularly magnetized\n  multilayers: We report on reversible electric-field-driven magnetic domain wall motion in\na Cu/Ni multilayer on a ferroelectric BaTiO$_3$ substrate. In our\nheterostructure, strain-coupling to ferroelastic domains with in-plane and\nperpendicular polarization in the BaTiO$_3$ substrate causes the formation of\ndomains with perpendicular and in-plane magnetic anisotropy, respectively, in\nthe Cu/Ni multilayer. Walls that separate magnetic domains are elastically\npinned onto ferroelectric domain walls. Using magneto-optical Kerr effect\nmicroscopy, we demonstrate that out-of-plane electric field pulses across the\nBaTiO$_3$ substrate move the magnetic and ferroelectric domain walls in unison.\nOur experiments indicate an exponential increase of domain wall velocity with\nelectric field strength and opposite domain wall motion for positive and\nnegative field pulses. Magnetic fields do not affect the velocity of magnetic\ndomain walls, but independently tailor their internal spin structure, causing a\nchange in domain wall dynamics at high velocities."
    },
    {
        "anchor": "Charting Lattice Thermal Conductivity of Inorganic Crystals: Thermal conductivity is a fundamental material property but challenging to\npredict, with less than 5% out of about $10^5$ synthesized inorganic materials\nbeing documented. In this work, we extract the structural chemistry that\ngoverns lattice thermal conductivity, by combining graph neural networks and\nrandom forest approaches. We show that both mean and variation of unit-cell\nconfigurational properties, such as atomic volume and bond length, are the most\nimportant features, followed by mass and elemental electronegativity. We chart\nthe structural chemistry of lattice thermal conductivity into extended\nvan-Arkel triangles, and predict the thermal conductivity of all known\ninorganic materials in the Inorganic Crystal Structure Database. For the\nlatter, we develop a transfer learning framework extendable for other\napplications.",
        "positive": "Tailoring the magnetism of GaMnAs films by ion irradiation: Ion irradiation of semiconductors is a well understood method to tune the\ncarrier concentration in a controlled manner. We show that the ferromagnetism\nin GaMnAs films, known to be hole-mediated, can be modified by He ion\nirradiation. The coercivity can be increased by more than three times. The\nmagnetization, Curie temperature and the saturation field along the\nout-of-plane hard axis all decrease as the fluence increases. The electrical\nand structural characterization of the irradiated GaMnAs layers indicates that\nthe controlled tailoring of magnetism results from a compensation of holes by\ngenerated electrical defects."
    },
    {
        "anchor": "Phonon hydrodynamics and ultrahigh-room-temperature thermal conductivity\n  in thin graphite: Allotropes of carbon, such as diamond and graphene, are among the best\nconductors of heat. We monitored the evolution of thermal conductivity in thin\ngraphite as a function of temperature and thickness and found an intimate link\nbetween high conductivity, thickness, and phonon hydrodynamics. The room\ntemperature in-plane thermal conductivity of 8.5-micrometer-thick graphite was\n4300 watts per meter-kelvin-a value well above that for diamond and slightly\nlarger than in isotopically purified graphene. Warming enhances thermal\ndiffusivity across a wide temperature range, supporting partially hydrodynamic\nphonon flow. The enhancement of thermal conductivity that we observed with\ndecreasing thickness points to a correlation between the out-of-plane momentum\nof phonons and the fraction of momentum relaxing collisions. We argue that this\nis due to the extreme phonon dispersion anisotropy in graphite.",
        "positive": "Ultrathin film of 3D topological insulators by vapor-phase epitaxy:\n  Surface dominant transport in wide temperature revealed by Seebeck\n  measurement: Realization of intrinsic surface dominant transport in a wide temperature\nregion for a topological insulators (TIs) is an important frontier research in\norder to promote the progresses of TIs towards the future electronics. We\nreport here systematic measurements of longitudinal electrical transport,\nShubnikov-de-Haas (SdH) quantum oscillations, Hall coefficient (R_H^2D), and\nSeebeck coefficient as a function of film thickness (d) and temperature using\nhigh quality Bi2-xSbxTe3-ySey (BSTS) single crystal thin films grown by\nphysical vapor-phase deposition. The thickness dependence of sheet conductance\nand Seebeck coefficient clearly show the suppression of semiconducting hole\ncarriers of bulk states by reducing film thickness, reaching to the surface\ndominant transport at below dc=14 nm. Quantitative arguments are made as to how\nthe contribution of itinerant carrier number (n) can be suppressed, using both\nR_H^2D (n_Hall^2D) and SdH (n_SdH). Intriguingly, the value of n_Hall^2D\napproaches to be twice of n_SdH below dc. While R_H^2D shows a negative sign in\nwhole temperature region, a change from negative to positive polarity is\nclearly observed for S at high temperatures when d is thick. We point out that\nthis inconsistency observed between R_H^2D and S is intrinsic in 3D-TIs and its\norigin is the large difference in carrier mobility between the bulk and the\ntopological surface. We propose that Seebeck coefficient can become a\nconvenient and powerful tool to evaluate the intrinsic carrier concentration\nfor the topological surface in 3D-TIs even in the absence of magnetic field."
    },
    {
        "anchor": "Generation of nitrogen-vacancy ensembles in diamond for quantum sensors:\n  Optimization and scalability of CVD processes: Ensembles of nitrogen-vacancy (NV) centers in diamond are a leading platform\nfor practical quantum sensors. Reproducible and scalable fabrication of\nNV-ensembles with desired properties is crucial. This work addresses these\nchallenges by developing a chemical vapor deposition (CVD) synthesis process to\nproduce diamond material at scale with improved NV-ensemble properties for a\ntarget NV density. The material reported in this work enables immediate\nsensitivity improvements for current devices. In addition, techniques\nestablished in this work for material and sensor characterization at different\nstages of the CVD synthesis process provide metrics for future efforts\ntargeting other NV densities or sample geometries.",
        "positive": "Thermal conductivity in intermetallic clathrates: A first principles\n  perspective: Inorganic clathrates such as Ba$_8$Ga$_{x}$Ge$_{46-x}$ and\nBa$_8$Al$_{x}$Si$_{46-x}$ commonly exhibit very low thermal conductivities. A\nquantitative computational description of this important property has proven\ndifficult, in part due to the large unit cell, the role of disorder, and the\nfact that both electronic carriers and phonons contribute to transport. Here,\nwe conduct a systematic analysis of the temperature and composition dependence\nof low-frequency modes associated with guest species in\nBa$_8$Ga$_{x}$Ge$_{46-x}$ and Ba$_8$Al$_{x}$Si$_{46-x}$ (\"rattler modes\"), as\nwell as of thermal transport in stoichiometric Ba$_8$Ga$_{16}$Ge$_{30}$. To\nthis end, we account for phonon-phonon interactions by means of temperature\ndependent effective interatomic force constants (TDIFCs), which we find to be\ncrucial in order to achieve an accurate description of the lattice part of the\nthermal conductivity. While the analysis of the thermal conductivity is often\nlargely focused on the rattler modes, here, it is shown that at room\ntemperatures modes with $\\hbar\\omega\\gtrsim\\,10\\,\\text{meV}$ account for 50\\%\\\nof lattice heat transport. Finally, the electronic contribution to the thermal\nconductivity is computed, which shows the Wiedemann-Franz law to be only\napproximately fulfilled. As a result, it is crucial to employ the correct\nprefactor when separating electronic and lattice contributions for experimental\ndata."
    },
    {
        "anchor": "Pressure induced electronic topological transition in Sb2S3: Pressure induced electronic topological transitions in the wide band gap\nsemiconductor Sb2S3 (Eg = 1.7-1.8 eV) with similar crystal symmetry (SG: Pnma)\nto its illustrious analog, Sb2Se3, has been studied using Raman spectroscopy,\nresistivity and the available literature on the x-ray diffraction studies. In\nthis report, the vibrational and the transport properties of Sb2S3 have been\nstudied up to 22 GPa and 11 GPa, respectively. We observed the softening of\nphonon modes Ag(2), Ag(3) and B2g and a sharp anomaly in their line widths at 4\nGPa. The resistivity studies also shows an anomaly around this pressure. The\nchanges in resistivity as well as Raman line widths can be ascribed to the\nchanges in the topology of the Fermi surface which induces the electron-phonon\nand the strong phonon-phonon coupling, indicating a clear evidence of the\nelectronic topological transition (ETT) in Sb2S3. The pressure dependence of\na/c ratio plot obtained from the literature showed a minimum at ~ 5 GPa, which\nis consistent with our high pressure Raman and resistivity results. Finally, we\ngive the plausible reasons for the non-existence of a non-trivial topological\nstate in Sb2S3 at high pressures.",
        "positive": "Inducing a Tunable Skyrmion-Antiskyrmion System through Ion Beam\n  Modification of FeGe Films: Skyrmions and antiskyrmions are nanoscale swirling textures of magnetic\nmoments formed by chiral interactions between atomic spins in magnetic\nnon-centrosymmetric materials and multilayer films with broken inversion\nsymmetry. These quasiparticles are of interest for use as information carriers\nin next-generation, low-energy spintronic applications. To develop\nskyrmion-based memory and logic, we must understand skyrmion-defect\ninteractions with two main goals -- determining how skyrmions navigate\nintrinsic material defects and determining how to engineer disorder for optimal\ndevice operation. Here, we introduce a tunable means of creating a\nskyrmion-antiskyrmion system by engineering the disorder landscape in FeGe\nusing ion irradiation. Specifically, we irradiate epitaxial B20-phase FeGe\nfilms with 2.8 MeV Au$^{4+}$ ions at varying fluences, inducing amorphous\nregions within the crystalline matrix. Using low-temperature electrical\ntransport and magnetization measurements, we observe a strong topological Hall\neffect with a double-peak feature that serves as a signature of skyrmions and\nantiskyrmions. These results are a step towards the development of information\nstorage devices that use skyrmions and anitskyrmions as storage bits and our\nsystem may serve as a testbed for theoretically predicted phenomena in\nskyrmion-antiskyrmion crystals."
    },
    {
        "anchor": "Non-Hermitian bonding and electronic reconfiguration of Ba$_2$ScNbO$_6$\n  and Ba$_2$LuNbO$_6$: Despite the extensive applications of perovskite compounds, the precise\nnature of non-Hermitian bonding in these materials remains poorly understood.\nIn this study, density functional theory calculations were performed to\ndetermine the electronic structures of perovskite compounds. In particular, the\nbandgaps of Ba$_2$ScNbO$_6$ and Ba$_2$LuNbO$_6$ were found to be 2.617 and\n2.629 eV, respectively, and the deformation bond energies and non-Hermitian\nbonding of these compounds were calculated. The relationship between the\nnon-Hermitian zeros of the O-Nb bond of Ba$_2$ScNbO$_6$ and the non-Hermitian\nzeros of the Sc-O bond was found to be similar but with varying sizes. Further,\nin-depth research on the non-Hermitian chemistry verified that precise control\nof atomic bonding and electron states can be achieved, providing new insights\ninto the study of chemical bonds.",
        "positive": "Engineering Chemo-Mechanical Properties of Zn Surfaces via Alucone\n  Coating: Aqueous zinc (Zn)-ion batteries (AZIB) are promising candidates for the\nnext-generation energy store systems due to their high capacity and low cost.\nDespite their nominal performance, Zn anodes tend to rapidly develop dendrite\nand fracture, leading to substantial capacity loss and cycling stability\nfailure. Well-controlled coating using organic-inorganic hybrid molecules is\nhighly promising to substantially improve their chemo-mechanical stability\nwithout compromising their performance. We herein present a critical assessment\nof the chemical and mechanical stability of alucone-coated Zn surfaces using\nfirst-principles simulations. Negative adsorption energies indicate strong\ncohesive strengths between alucone and the selected Zn surfaces. Energetically\nfavorable alucone coatings are further verified by charge transfer at\ninterfaces as seen through Bader charge analysis. Negative surface stress\nprofiles at alucone coated interface are mostly responsible for surface\nreconstruction. The contributions of surface elastic constants are dependent on\nthe selection of slip planes and the thickness of the thin film. By considering\nplane stress conditions, we calculate the mechanical properties which indicate\nthe ductility of the alucone-coated basal thin film."
    },
    {
        "anchor": "Indole moiety induced biological potency in pseudo- peptides derived\n  from 2-amino-2-(1H-indole-2-yl) based acetamides: synthesis, structure and\n  computational investigations: We report the synthesis and theoretical investigations of three novel\npseudo-peptide molecules derived from 2-amino-2-(1H-indole-2-yl) acetamides.\nThe compounds were subjected to spectroscopic characterization ($^1$H,\n$^{13}$C-NMR and MS) and their chemical, electronic, and optical properties\nhave been investigated. To ascertain their potential pharmacological\napplicability, the prospective reactive centers and molecular sites prone to\ninteraction with water were identified along with possible sensitivity to\nautoxidation. Further, we have studied the optical response in the presence of\ndifferent solvents and compared the electronic and optical properties of the\npristine molecules. We highlight the subtle dependence of the properties on the\nstructure and composition of these pseudo-peptides. Our results indicate that\nthese molecules have high pharmaceutical potential and could serve as lead\ncomponents in new drug formulations.",
        "positive": "Single Gate P-N Junctions in Graphene-Ferroelectric Devices: Graphene's linear dispersion relation and the attendant implications for\nbipolar electronics applications have motivated a range of experimental efforts\naimed at producing p-n junctions in graphene. Here we report electrical\ntransport measurements of graphene p-n junctions formed via simple\nmodifications to a PbZr$_{0.2}$Ti$_{0.8}$O$_3$ substrate, combined with a\nself-assembled layer of ambient environmental dopants. We show that the\nsubstrate configuration controls the local doping region, and that the p-n\njunction behavior can be controlled with a single gate. Finally, we show that\nthe ferroelectric substrate induces a hysteresis in the environmental doping\nwhich can be utilized to activate and deactivate the doping, yielding an\n`on-demand' p-n junction in graphene controlled by a single, universal\nbackgate."
    },
    {
        "anchor": "The formation and ordering of local magnetic moments in Fe-Al alloys: With density functional theory, studied are the local magnetic moments in\nFe-Al alloys depending on concentration and Fe nearest environment. At zero\ntemperature, the system can be in different states: ferromagnetic,\nantiferromagnetic and spin-spiral waves (SSW) which has a minimum energy. Both\nSSW and negative moment of Fe atoms with many Al atoms around them agree with\nexperiments. Magnetization curves taken from literature are analysed.\nAssumption on percolation character of size distribution of magnetic clusters\ndescribes well the experimental superparamagnetic behaviour above 150 K.",
        "positive": "Ultrafast melting of charge-density wave fluctuations at room\n  temperature in ${1T-TiSe_2}$ monitored under non-equilibrium conditions: We investigate the ultrafast lattice dynamics in ${1T-TiSe_2}$ using\nfemtosecond reflection pump-probe and pump-pump-probe techniques at room\ntemperature. The time-domain signals and Fourier-transformed spectra show the\n$A_{1g}$ phonon mode at 5.9 THz. Moreover, we observe an additional mode at\n$\\approx$ 3 THz, corresponding to the charge-density wave (CDW) amplitude mode,\nwhich is generally visible below T$_c \\approx 200\\ $K. We argue that the\nemergence of the CDW amplitude mode at room temperature can be a consequence of\nfluctuations of order parameters, based on the additional experiment using the\npump-pump-probe technique, which exhibited suppression of the AM signal within\nthe ultrafast time scale of $\\sim$ 0.5 ps."
    },
    {
        "anchor": "Visualization of reaction chemistry in W-KClO4-BaCrO4 delay mixtures via\n  a Sestak-Berggren model based isoconversional method: The combustion delay mixture of tungsten (W), potassium perchlorate (KClO4),\nand barium chromate (BaCrO4), also known as the WKB mixture, has long been\nconsidered to be an integral part of military-grade ammunition. Despite its\nlong history, however, their progressive reaction dynamics remains a question\nmark, especially due to the complex nature of their combustion reaction. As\nopposed to a one-step oxidation commonly observed in conventional combustions,\nthe WKB mixture is associated with a multibody reaction between its solid-state\ncomponents. To this end, the emergence of three combustion peaks, which we\ncorresponded with disparate chemical reactions, was observed using\nthermogravimetric analysis on two separate WKB mixtures with differing mixture\nratios. We applied the stepwise isoconversional method on each of the peaks to\nmatch the combustion chemistry it represents to the Sestak-Berggren model and\ncomputed the conceptual activation energy. Further plotting the logarithmic\npre-exponential factor as a function of the reaction progress, we demonstrate a\nmethod of using the plot as an intuitive tool to understand the dynamics of\nindividual reactions that compose multi-step chemical reactions. Our study\nprovides a systematic approach in visualizing the reaction chemistry, thereby\nstrengthening the analytical arsenal against reaction dynamics of combustion\ncompounds in general.",
        "positive": "The Structure of the Nonlinear Elastic Zone near the Tip of a Rapid\n  Brittle Crack: This paper has been withdrawn by the authors due to new available results. A\nrevised version, that incorporates the new results, will be submitted later."
    },
    {
        "anchor": "Three-nodal surface phonons in solid-state materials: Theory and\n  material realization: This year, Liu \\textit{et al}. [Phys. Rev. B \\textbf{104}, L041405 (2021)]\nproposed a new class of topological phonons (TPs; i.e., one-nodal surface (NS)\nphonons), which provides an effective route for realizing one-NSs in phonon\nsystems. In this work, based on first-principles calculations and symmetry\nanalysis, we extended the types of NS phonons from one- to three-NS phonons.\nThe existence of three-NS phonons (with NS states on the $k_{i}$ = $\\pi$ ($i$ =\n$x$, $y$, $z$) planes in the three-dimensional Brillouin zone (BZ)) is enforced\nby the combination of two-fold screw symmetry and time reversal symmetry. We\nscreened all 230 space groups (SGs) and found nine candidate groups (with the\nSG numbers (Nos.) 19, 61, 62, 92, 96, 198, 205, 212, and 213) hosting three-NS\nphonons. Interestingly, with the help of first-principles calculations, we\nidentified $P2_{1}$2$_{1}$2$_{1}$-type YCuS$_{2}$ (SG No. 19), $Pbca$-type\nNiAs$_{2}$ (SG No. 61), $Pnma$-type SrZrO$_{2}$ (SG No. 62),\n$P4_{1}$2$_{1}$2-type LiAlO$_{2}$ (SG No. 92), $P4_{3}$2$_{1}$2-type ZnP$_{2}$\n(SG No. 96), $P2_{1}$3-type NiSbSe (SG No. 198), $Pa\\bar{3}$-type As$_{2}$Pt\n(SG No. 205), $P4_{3}$32-type BaSi$_{2}$ (SG No. 212), and $P4_{1}$32-type\nCsBe$_{2}$F$_{5}$ (SG No. 213) as realistic materials hosting three-NS phonons.\nThe results of our presented study enrich the class of NS states in phonon\nsystems and provide concrete guidance for searching for three-NS phonons and\nsingular Weyl point phonons in realistic materials.",
        "positive": "Magnetism of Hexagonal Mn1.5X0.5Sn (X = Cr, Mn, Fe, Co) Nanomaterials: Mn1.5X0.5Sn (X = Cr, Mn, Fe, Co) nanomaterials in the hexagonal Ni2In-type\ncrystal structure have been prepared using arc-melting and melt spinning. All\nthe rapidly quenched Mn1.5X0.5Sn alloys show moderate saturation magnetizations\nwith the highest value of 458 emu/cm3 for Mn1.5Fe0.5Sn, but their Curie\ntemperatures are less than 300 K. All samples except the Cr containing one show\nspin-glass-like behavior at low temperature. The magnetic anisotropy constants\ncalculated from the high-field magnetization curves at 100 K are on the order\nof 1 Merg/cm3. The vacuum annealing of the ribbons at 550 oC significantly\nimproved their magnetic properties with the Curie temperature increasing from\n206 K to 273 K for Mn1.5Fe0.5Sn."
    },
    {
        "anchor": "Cepstral Scanning Transmission Electron Microscopy Imaging of Severe\n  Lattice Distortions: The development of four-dimensional (4D) scanning transmission electron\nmicroscopy (STEM) using fast detectors has opened-up new avenues for addressing\nsome of long-standing challenges in electron imaging. One of these challenges\nis how to image severely distorted crystal lattices, such as at a dislocation\ncore. Here we introduce a new 4D-STEM technique, called Cepstral STEM, for\nimaging disordered crystals using electron diffuse scattering. Local\nfluctuations of diffuse scattering are captured by scanning electron\nnanodiffraction (SEND) using a coherent probe. The harmonic signals in electron\ndiffuse scattering are detected through Cepstral analysis and used for imaging.\nBy integrating Cepstral analysis with 4D-STEM, we demonstrate that information\nabout the distortive part of electron scattering potential can be separated and\nimaged at nm spatial resolution. We apply our technique to the analysis of a\ndislocation core in SiGe and lattice distortions in high entropy alloy.",
        "positive": "Electric polarization observed in single crystals of multiferroic\n  Lu2MnCoO6: We report electric polarization and magnetization measurements in single\ncrystals of double perovskite Lu2MnCoO6 using pulsed magnetic fields and\noptical second harmonic generation (SHG) in DC magnetic fields. we observe\nwell-resolved magnetic field-induced changes in the electric polarization in\nsingle crystals and thereby resolve the question about whether multiferroic\nbehavior is intrinsic to these materials or an extrinsic feature of\npolycrystals. We find electric polarization along the crystalline b-axis, that\nis suppressed by applying a magnetic fields along c-axis and advance a model\nfor the origin of magnetoelectric coupling. We furthermore map the phase\ndiagram using both capacitance and electric polarization to identify regions of\nordering and regions of magnetoelectric hysteresis. This compound is a rare\nexample of coupled hysteretic behavior in the magnetic and electric properties.\nThe ferromagnetic-like magnetic hysteresis loop that couples to hysteretic\npolarization can be attributed not to ordinary ferromagnetic domains, but to\nthe rich physics of magnetic frustration of Ising-like spins in the axial\nnext-nearest neighbor interaction model."
    },
    {
        "anchor": "Surface energy calculations from Zinc blende (111)/(-1-1-1) to Wurtzite\n  (0001)/(000-1):a study of ZnO and GaN: The accurate absolute surface energies of (0001)/(000-1) surfaces of wurtzite\nstructures are crucial in determining the thin film growth mode of important\nenergy materials. However, the surface energies still remain to be solved due\nto the intrinsic difficulty of calculating dangling bond energy of\nasymmetrically bonded surface atoms. In this study, we used a pseudo-hydrogen\npassivation method to estimate the dangling bond energy and calculate the polar\nsurfaces of ZnO and GaN. The calculations were based on the pseudo chemical\npotentials obtained from a set of tetrahedral clusters or simple\npseudo-molecules, using density functional theory approaches. And the surface\nenergies of (0001)/(000-1) surfaces of wurtzite ZnO and GaN we obtained showed\nrelatively high self-consistencies. A wedge structure calculation with a new\nbottom surface passivation scheme of group I and group VII elements was also\nproposed and performed to show converged absolute surface energy of wurtzite\nZnO polar surfaces, and the result were also compared with the above method.\nThese calculations and comparisons may provide important insights to crystal\ngrowths of the above materials, thereby leading to significant performance\nenhancements of semiconductor devices.",
        "positive": "Concentration dependence of the fluorescence decay profile in transition\n  metal doped chalcogenide glass: In this paper we present the fluorescence decay profiles of vanadium and\ntitanium doped gallium lanthanum sulphide (GLS) glass at various doping\nconcentrations between 0.01 and 1% (molar). We demonstrate that below a\ncritical doping concentration the fluorescence decay profile can be fitted with\nthe stretched exponential function: exp[-(t/{\\tau})\\b{eta}], where {\\tau} is\nthe fluorescence lifetime and \\b{eta} is the stretch factor. At low\nconcentrations the lifetime for vanadium and titanium doped GLS was 30 {\\mu}s\nand 67 {\\mu}s respectively. We validate the use of the stretched exponential\nmodel and discuss the possible microscopic phenomenon it arises from. We also\ndemonstrate that above a critical doping concentration of around 0.1% (molar)\nthe fluorescence decay profile can be fitted with the double exponential\nfunction: a*exp-(t/{\\tau}1)+ b*exp-(t/{\\tau}2), where {\\tau}1and {\\tau}2 are\ncharacteristic fast and slow components of the fluorescence decay profile, for\nvanadium the fast and slow components are 5 {\\mu}s and 30 {\\mu}s respectively\nand for titanium they are 15 {\\mu}s and 67 {\\mu}s respectively. We also show\nthat the fluorescence lifetime of vanadium and titanium at low concentrations\nin the oxide rich host gallium lanthanum oxy-sulphide (GLSO) is 43 {\\mu}s and\n97 {\\mu}s respectively, which is longer than that in GLS. From this we deduce\nthat vanadium and titanium fluorescing ions preferentially substitute into high\nefficiency oxide sites until at a critical concentration they become saturated\nand low efficiency sulphide sites start to be filled."
    },
    {
        "anchor": "Electron-phonon interaction and spectral weight transfer in\n  Fe$_{1-x}$Co$_{x}$Si: A comprehensive ellipsometric study was performed on Fe$_{1-x}$Co$_{x}$Si\nsingle crystals in the spectral range from 0.01 eV to 6.2 eV. Direct and\nindirect band gaps of 73 meV and 10 meV, respectively, were observed in FeSi at\n7 K. One of four infrared-active phonons that is energetically close to the\ndirect absorption edge is coupled both to the electrons and to the low-energy\nphonon. This is evident from asymmetry in the phonon line shape and a reduction\nof its frequency when the absorption edge shifts across the phonon energy due\nto the temperature dependence of the direct band gap. As the temperature\nincreases, the indirect gap changes sign, which manifests as a transition from\na semiconductor to a semimetal. The corresponding gain of the spectral weight\nat low energies was recovered within an energy range of several eV. The present\nfindings strongly support the model indicating that Fe$_{1-x}$Co$_{x}$Si can be\nwell described in an itinerant picture, taking into account self-energy\ncorrections.",
        "positive": "A Monopole Mining Method for High Throughput Screening Weyl Semimetals: Although topological invariants have been introduced to classify the\nappearance of protected electronic states at surfaces of insulators, there are\nno corresponding indexes for Weyl semimetals whose nodal points may appear\nrandomly in the bulk Brillouin Zone (BZ). Here we use a well-known result that\nevery Weyl point acts as a Dirac monopole and generates integer Berry flux to\nsearch for the monopoles on rectangular BZ grids that are commonly employed in\nself-consistent electronic structure calculations. The method resembles data\nmining technology of computer science and is demonstrated on locating the Weyl\npoints in known Weyl semimetals. It is subsequently used in high throughput\nscreening several hundreds of compounds and predicting a dozen new materials\nhosting nodal Weyl points and/or lines."
    },
    {
        "anchor": "Thickness and growth-condition dependence of \\emph{in-situ} mobility and\n  carrier density of epitaxial thin-film Bi$_2$Se$_3$: Bismuth selenide Bi$_2$Se$_3$ was grown by molecular beam epitaxy while\ncarrier density and mobility were measured directly \\emph{in situ} as a\nfunction of film thickness. Carrier density shows high interface n-doping (1.5\nx 10$^{13}$ cm$^{-2}$) at the onset of film conduction, and bulk dopant density\nof $\\sim$5 x 10$^{18}$ cm$^{-3}$, roughly independent of growth temperature\nprofile. Mobility depends more strongly on the growth temperature and is\nrelated to the crystalline quality of the samples quantified by \\emph{ex-situ}\nAFM measurements. These results indicate that Bi$_2$Se$_3$ as prepared by\nwidely employed parameters is \\emph{n}-doped before exposure to atmosphere, the\ndoping is largely interfacial in origin, and dopants are not the limiting\ndisorder in present Bi$_2$Se$_3$ films.",
        "positive": "Electrical Degradation in Dielectric and Piezoelectric Oxides: Review of\n  Defect Chemistry and Associated Characterization Techniques: The properties of dielectric and piezoelectric oxides are determined by their\nprocessing history, crystal structure, chemical composition, microstructure,\ndopants (or defect) distribution, and defect kinetics. These materials are\nessential in a diverse range of applications including aerospace, medical,\nmilitary, transportation, power engineering, and communication, where they are\nused as ceramic discs, thick and thin films, multilayer devices, etc.\nSignificant advances in understanding the materials, processing, properties,\nand reliability of these materials have led to their widespread use in consumer\nelectronics, military, and aerospace applications. This review delves into\nelectrical degradation in dielectrics and piezoelectrics, focusing on defect\nchemistry and key characterization techniques. It also provides a detailed\ndiscussion of various spectroscopic, microscopic, and electronic\ncharacterization techniques essential for analyzing defects and degradation\nmechanisms."
    },
    {
        "anchor": "Influence of solvation on the structural and capacitive properties of\n  electrical double layer capacitors: We use molecular dynamics simulations to explore the impact of a non-ionic\nsolvent on the structural and capacitive properties of supercapacitors based on\nan ionic liquid electrolyte and carbon electrodes. The study is focused on two\npure ionic liquids, namely 1-butyl-3-methylimidazolium hexafluorophosphate and\n1-butyl-3-methylimidazolium tetrafluoroborate, and their 1.5 M solutions in\nacetonitrile. The electrolytes, represented by coarse-grained models, are\nenclosed between graphite electrodes. We employ a constant potential\nmethodology which allows us to gain insight into the influence of solvation on\nthe polarization of the electrodes as well as the structural and capacitive\nproperties of the electrolytes at the interface. We show that the interfacial\ncharacteristics, different for two distinct pure ionic liquids, become very\nsimilar upon mixing with acetonitrile.",
        "positive": "Electronic and Vibrational Properties of gamma-AlH3: Aluminum hydride (alane) AlH_3 is an important material in hydrogen storage\napplications. It is known that AlH_3 exists in multiply forms of polymorphs,\nwhere $\\alpha$-AlH_3 is found to be the most stable with a hexagonal structure.\nRecent experimental studies on $\\gamma$-AlH_3 reported an orthorhombic\nstructure with a unique double-bridge bond between certain Al and H atoms. This\nwas not found in $\\alpha$-AlH_3 or other polymorphs. Using density functional\ntheory, we have investigated the energetics, and the structural, electronic,\nand phonon vibrational properties for the newly reported $\\gamma$-AlH_3\nstructure. The current calculation concludes that $\\gamma$-AlH_3 is less stable\nthan $\\alpha$-AlH_3 by 2.1 KJ/mol. Interesting binding features associated with\nthe unique geometry of $\\gamma$-AlH3 are discussed from the calculated\nelectronic properties and phonon vibrational modes. The binding of H-s with\nhigher energy Al-p,d orbitals is enhanced within the double-bridge arrangement,\ngiving rise to a higher electronic energy for the system. Distinguishable new\nfeatures in the vibrational spectrum of $\\gamma$-AlH_3 were attributed to the\ndouble-bridge and hexagonal-ring structures."
    },
    {
        "anchor": "Nonsingular stress and strain fields of dislocations and disclinations\n  in first strain gradient elasticity: The aim of this paper is to study the elastic stress and strain fields of\ndislocations and disclinations in the framework of Mindlin's gradient\nelasticity. We consider simple but rigorous versions of Mindlin's first\ngradient elasticity with one material length (gradient coefficient). Using the\nstress function method, we find modified stress functions for all six types of\nVolterra defects (dislocations and disclinations) situated in an isotropic and\ninfinitely extended medium. By means of these stress functions, we obtain exact\nanalytical solutions for the stress and strain fields of dislocations and\ndisclinations. An advantage of these solutions for the elastic strain and\nstress is that they have no singularities at the defect line. They are finite\nand have maxima or minima in the defect core region. The stresses and strains\nare either zero or have a finite maximum value at the defect line. The maximum\nvalue of stresses may serve as a measure of the critical stress level when\nfracture and failure may occur. Thus, both the stress and elastic strain\nsingularities are removed in such a simple gradient theory. In addition, we\ngive the relation to the nonlocal stresses in Eringen's nonlocal elasticity for\nthe nonsingular stresses.",
        "positive": "With no Color and Scent (part III): Architecture of metal shells grown\n  on templates by pulse current electrodeposition: A method of growing mushroom or shell like nanostructured metal convex\nconcave models has been worked out. Silver,copper,nickel,rhodium and\nPd-Ni,Pd-Co alloy structures are reproduced as a result of self-assembly of\nnanowires growing on porous membranes in the course of pulse current\nelectrodeposition. It is shown that the method allows to model not only the\nshell shape but also the hierarchical structure at the nano, micro and\nmesolevels. A 1,2 mm sized shell was grown from Pd-Ni alloy. The architecture\nof the models was studied by fragmentation and chemical etching. The images\nwere obtained using SUPRA 50 VP and JEOL scanning electron microscopes. The\nmetal shell is a bowl-shaped frame, its walls composed of densely packed\nnanoelements. Each nanoelement is a conical bundle of nanowires grown as a\nsupported wine glass. The shell inner surface is a weave of nanowires with a\nvegetation pattern with bottom up directed lines. The inner surface exhibits\nalso well pronounced transverse rings formed by the bottom up growing bundles\nof nanowires that compose the shell frame. A number of nanowire bundle ends\nrise to the shell outer surface as nanoflowers that can serve as templates for\ngrowing nanowires. In some cases the nanowires growing on the outer surface\nform a copy of plate mushroom. A hypothesis is proposed that pulsed growth on\nmembranes is a tool of morphogenesis of many mushrooms and plants."
    },
    {
        "anchor": "Search for Thermoelectrics with High Figure of Merit in half-Heusler\n  compounds with multinary substitution: In order to improve the thermoelectric performance of TiCoSb we have\nsubstituted 50% of Ti equally with Zr and Hf at Ti site and Sb with Sn and Se\nequally at Sb site. The electronic structure of Ti0.5Zr0.25Hf0.25CoSn0.5Se0.5\nis investigated using the full potential linearized augmented plane wave method\nand the thermoelectric transport properties are calculated on the basis of\nsemi-classical Boltzmann transport theory. Our band structure calculations show\nthat Ti0.5Zr0.25Hf0.25CoSn0.5Se0.5 has semiconducting behavior with indirect\nband gap value of 0.98 eV which follow the empirical rule of 18\nvalence-electron content to bring semiconductivity in half Heusler compounds,\nindicating that one can have semiconducting behavior in multinary phase of half\nHeusler compounds if they full fill the 18 VEC rule and this open-up the\npossibility of designing thermoelectrics with high figure of merit in half\nHeusler compounds. We show that at high temperature of around 700K\nTi0.5Zr0.25Hf0.25CoSn0.5Se0.5 has high thermoelectric figure of merit of ZT =\n1.05 which is higher than that of TiCoSb (~ 0.95) suggesting that by going from\nternary to multinary phase system one can enhance the thermoelectric figure of\nmerit at higher temperatures.",
        "positive": "Large Disparity Between Optical and Fundamental Band Gaps in Layered\n  In2Se3: In$_2$Se$_3$ is a semiconductor material that can be stabilized in different\ncrystal structures (at least one 3D and several 2D layered structures have been\nreported) with diverse electrical and optical properties. This feature has\nplagued its characterization over the years, with reported band gaps varying in\nan unacceptable range of 1 eV. Using first-principles calculations based on\ndensity functional theory and the HSE06 hybrid functional, we investigated the\nstructural and electronic properties of four layered phases of In$_2$Se$_3$,\naddressing their relative stability and the nature of their fundamental band\ngaps, i.e., direct {\\em versus} indirect. Our results show large disparities\nbetween fundamental and optical gaps. The absorption coefficients are found to\nbe as high as that in direct-gap III-V semiconductors. The band alignment with\nrespect to conventional semiconductors indicate a tendency to $n$-type\nconductivity, explaining recent experimental observations."
    },
    {
        "anchor": "Robust Dipolar Layers between Organic Semiconductors and Silver for\n  Energy-Level Alignment: The interface between a metal electrode and an organic semiconductor (OS)\nlayer has a defining role in the properties of the resulting device. To obtain\na desired performance, interlayers are introduced to modify the adhesion and\ngrowth of OS and enhance the efficiency of charge transport through the\ninterface. However, the employed interlayers face common challenges, including\na lack of electric dipoles to tune the mutual position of energy levels, being\ntoo thick for efficient electronic transport, or being prone to intermixing\nwith subsequently deposited OS layers. Here, we show that monolayers of\n1,3,5-tris(4 carboxyphenyl)benzene (BTB) with fully deprotonated carboxyl\ngroups on silver substrates form a compact layer resistant to intermixing while\nmediating energy level alignment and showing a large insensitivity to substrate\ntermination. Employing a combination of surface-sensitive techniques, i.e.,\nlow-energy electron microscopy and diffraction, X-ray photoelectron\nspectroscopy, and scanning tunneling microscopy, we have comprehensively\ncharacterized the compact layer and proven its robustness against mixing with\nthe subsequently deposited organic semiconductor layer. DFT calculations show\nthat the robustness arises from a strong interaction of carboxylate groups with\nthe Ag surface, and thus, the BTB in the first layer is energetically favored.\nSynchrotron radiation photoelectron spectroscopy shows that this layer displays\nconsiderable electrical dipoles that can be utilized for work function\nengineering and electronic alignment of molecular frontier orbitals with\nrespect to the substrate Fermi level. Our work thus provides a widely\napplicable molecular interlayer and general insights necessary for engineering\nof charge injection layers for efficient organic electronics.",
        "positive": "Understanding the origin of bandgap problem in transition and\n  post-transition metal oxides: Improving electronic structure calculations for practical and\ntechnologically-important materials has been a never-ending pursue. This is\nespecially true for transition and post-transition metal oxides for which the\ncurrent first-principles approaches still suffer various drawbacks. Here we\npresent a hierarchical-hybrid functional approach built on the use of\npseudopotentials. The key is to introduce a discontinuity in the exchange\nfunctional between core and valence electrons. It allows for treating the\nlocalization errors of sp and d electrons differently, which have been known to\nbe an important source of error for the band gap. Using ZnO as a prototype, we\nshow the approach is successful in simultaneously reproducing the band gap and\nd-band position. Remarkably, the same approach, without having to change the\nhybrid mixing parameters from those of Zn, works reasonably well for other\nbinary 3d transition and post-transition metal oxides across board. Our\nfindings point to a new direction of systematically improving the exchange\nfunctional in first-principles calculations."
    },
    {
        "anchor": "Evidence for metallic 1T phase, 3d1 electronic configuration and charge\n  density wave order in molecular-beam epitaxy grown monolayer VTe2: We present a combined experimental and theoretical study of monolayer VTe2\ngrown on highly oriented pyrolytic graphite by molecular-beam epitaxy. Using\nvarious in-situ microscopic and spectroscopic techniques, including scanning\ntunneling microscopy/spectroscopy, synchrotron X-ray and angle-resolved\nphotoemission, and X-ray absorption, together with theoretical analysis by\ndensity functional theory calculations, we demonstrate direct evidence of the\nmetallic 1T phase and 3d1 electronic configuration in monolayer VTe2 that also\nfeatures a (4 x 4) charge density wave order at low temperatures. In contrast\nto previous theoretical predictions, our element-specific characterization by\nX-ray magnetic circular dichroism rules out a ferromagnetic order intrinsic to\nthe monolayer. Our findings provide essential knowledge necessary for\nunderstanding this interesting yet less explored metallic monolayer in the\nemerging family of van der Waals magnets.",
        "positive": "Evaluation of the low-lying energy spectrum of magnetic Keplerate\n  molecules with DMRG: We apply the density-matrix renormalization group technique to magnetic\nmolecules in order to evaluate the low-lying energy spectrum. In particular, we\ninvestigate the giant Keplerate molecule Mo72Fe30 where 30 Fe3+ ions (spins\n5/2) occupy the sites of an icosidodecahedron and interact via nearest-neighbor\nantiferromagnetic Heisenberg exchange.\n  The aim of our investigation is to verify the applicability and feasibility\nof DMRG calculations for complex magnetic molecules. To this end we first use a\nfictitious molecule with the same structure as Mo72Fe30 but with spins 1/2 as a\ntest system. Here we investigate the accuracy of our DMRG implementation in\ncomparison to numerically exact results. Then we apply the algorithm to\nMo72Fe30 and calculate an approximation of the lowest energy levels in the\nsubspaces of total magnetic quantum number. The results prove the existence of\na lowest rotational band, which was predicted recently."
    },
    {
        "anchor": "Multiple Charge density waves and lattice superstructures in thin-layer\n  TmTe2 and TmTe3: We have grown thulium tellurides (TmTe2, TmTe3) thin layers (less than four\nlayers) on graphene/SiC (0001) by molecular beam epitaxy. The charge density\nwaves (CDWs) and lattice superstructures (LSs) are investigated by scanning\ntunneling microscopy. Clear CDW patterns in real space are observed on surface\nof metallic TmTe3. Two CDWs are with wave vectors 0.29c* and 0.31a*\nrespectively. LSs with various periods are unveiled on the surface of TmTe2 and\nTmTe3. The electronic structures of these films are semiconducting. These\nresults show that superstructures in rare earth tellurides can have two\norigins, CDWs or LSs.",
        "positive": "Two-dimensional coherent photocurrent excitation spectroscopy in a\n  polymer solar cell: In high-performance solar cells based on polymeric semiconductors, the\nmechanism of photocarrier generation on $<100$-fs timescales is yet to be\nunravelled. In particular the dynamics of early-time electronic coupling\nbetween excitons on polymer chains and charge-transfer states need to be\ninvestigated in order to develop a detailed picture of ultrafast processes\ninvolved in photocurrent production. In this proceeding, we report preliminary\nmeasurements using a novel spectroscopy that can measure such correlations:\ntwo-dimensional coherent photocurrent excitation spectroscopy. This nonlinear\ntechnique measures off-diagonal spectral correlations in a two-dimensional\nphotocurrent excitation spectrum. We interpret these sectroscopic measurements\nin light of recent theoretical predictions."
    },
    {
        "anchor": "Reproducible Performance Improvements to Monolayer MoS2 Transistors\n  through Exposed Material Forming Gas Annealing: Metal-mediated exfoliation has been demonstrated as a promising approach for\nobtaining large-area flakes of 2D materials to fabricate prototypical\nnanoelectronics. However, several processing challenges related to organic\ncontamination at the interfaces of the 2D material and the gate oxide must be\novercome to realize robust devices with high yield. Here, we demonstrate an\noptimized process to realize high-performance field-effect transistor (FET)\narrays from large-area (~5000 um2) monolayer MoS2 with a yield of 85 %. A\ncentral element of this process is an exposed material forming gas anneal\n(EM-FGA) that results in uniform FET performance metrics (i.e., field-effect\nmobilities, threshold voltages, and contact performance). Complementary\nanalytical measurements show that the EM-FGA process reduces deleterious\nchannel doping effects by decreasing organic contamination, while also reducing\nthe prevalence of insulating molybdenum oxide, effectively improving the\nMoS2-gate oxide interface. The uniform FET performance metrics and high device\nyield achieved by applying the EM-FGA technique on large-area 2D material\nflakes will help advance the fabrication of complex 2D nanoelectronics devices\nand demonstrates the need for improved engineering of the 2D material-gate\noxide interface.",
        "positive": "Stabilization of coupled Dzyaloshinskii domain walls in fully\n  compensated synthetic anti-ferromagnets: We examine the combined effects of interlayer exchange coupling (IEC) and the\ninterfacial Dzyaloshinskii-Moriya Interaction (DMI) on the structure of\nmagnetic domain walls in fully compensated synthetic anti-ferromagnets (SAFs).\nIr-based SAFs with ferromagnetic (FM) layers based on [Pt/(Co/Ni)M]N were\ncharacterized by Lorentz transmission electron microscopy (LTEM). The\nmulti-layer design of the individual ferromagnetic layers enables control of\nthe interfacial Dzyaloshinskii-Moriya interaction (via 'M') and, in turn, the\nstructure and chirality of domain walls (DWs). We compare the Fresnel-mode LTEM\nimages in SAF designs with only a change in the purported strength of the DMI.\nThe existence of anti-ferromagnetically coupled Dzyaloshinskii domain walls\n(DWs) in a high DMI SAF is confirmed through application of in-situ\nperpendicular magnetic field and sample tilt. This conclusion is based on a\nunique set of conditions required to observe contrast in Fresnel-mode LTEM,\nwhich we outline in this document."
    },
    {
        "anchor": "All-electron self-consistent GW in the Matsubara-time domain:\n  implementation and benchmarks of semiconductors and insulators: The GW approximation is a well-known method to improve electronic structure\npredictions calculated within density functional theory. In this work, we have\nimplemented a computationally efficient GW approach that calculates central\nproperties within the Matsubara-time domain using the modified version of Elk,\nthe full-potential linearized augmented plane wave (FP-LAPW) package.\nContinuous-pole expansion (CPE), a recently proposed analytic continuation\nmethod, has been incorporated and compared to the widely used Pade\napproximation. Full crystal symmetry has been employed for computational\nspeedup. We have applied our approach to 18 well-studied\nsemiconductors/insulators that cover a wide range of band gaps computed at the\nlevels of single-shot G0W0, partially self-consistent GW0, and fully\nself-consistent GW (scGW). Our calculations show that G0W0 leads to band gaps\nthat agree well with experiment for the case of simple s-p electron systems,\nwhereas scGW is required for improving the band gaps in 3-d electron systems.\nIn addition, GW0 almost always predicts larger band gap values compared to\nscGW, likely due to the substantial underestimation of screening effects. Both\nthe CPE method and Pade approximation lead to similar band gaps for most\nsystems except strontium titantate, suggesting further investigation into the\nlatter approximation is necessary for strongly correlated systems. Our computed\nband gaps serve as important benchmarks for the accuracy of the Matsubara-time\nGW approach.",
        "positive": "Monte Carlo calculations of Curie temperatures of\n  Y$_{1-x}$Gd$_x$(Fe$_{1-y}$Co$_y$)$_2$ pseudobinary system: The close-packed AB$_2$ structures called Laves phases constitute the largest\ngroup of intermetallic compounds. In this paper we computationally investigated\nthe pseudo-binary Laves phase system Y$_{1-x}$Gd$_x$(Fe$_{1-y}$Co$_y$)$_2$\nspanning between the YFe$_2$, YCo$_2$, GdFe$_2$, and GdCo$_2$ vertices. While\nthe vast majority of the Y$_{1-x}$Gd$_x$(Fe$_{1-y}$Co$_y$)$_2$ phase diagram is\nthe ferrimagnetic phase, YCo$_2$ along with a narrow range of concentrations\naround it is the paramagnetic phase. We presented results obtained by Monte\nCarlo simulations of the Heisenberg model with parameters derived from\nfirst-principles calculations. For calculations, we used the Uppsala atomistic\nspin dynamics (UppASD) code together with the spin-polarized relativistic\nKorringa-Kohn-Rostoker (SPR-KKR) code. From first principles we calculated the\nmagnetic moments and exchange integrals for the considered pseudo-binary\nsystem, together with spin-polarized densities of states for boundary\ncompositions. Furthermore, we showed how the compensation point with the\neffective zero total moment depends on the concentration in the considered\nferrimagnetic phases. However, the main result of our study was the\ndetermination of the Curie temperature dependence for the system\nY$_{1-x}$Gd$_x$(Fe$_{1-y}$Co$_y$)$_2$. Except for the paramagnetic region\naround YCo$_2$, the predicted temperatures were in good qualitative and\nquantitative agreement with experimental results, which confirmed the ability\nof the method to predict magnetic transition temperatures for systems\ncontaining up to three different magnetic elements (Fe, Co, and Gd)\nsimultaneously. For the Y(Fe$_{1-y}$Co$_y$)$_2$ and Gd(Fe$_{1-y}$Co$_y$)$_2$\nsystems our calculations matched the experimentally-confirmed\nSlater-Pauling-like behavior of T$_C$ dependence on the Co concentration."
    },
    {
        "anchor": "Erratum: Landau Analysis of the Symmetry of the Magnetic Structure and\n  Magnetoelectric Interaction in Multiferroics [Phys. Rev. B 76, 05447 (2007)]: An error in the spin wavefunction for the rare earth sublattices of TbMn_2O_5\nis corrected.",
        "positive": "Sub 20 nm Short Channel Carbon Nanotube Transistors: Carbon nanotube field-effect transistors with sub 20 nm long channels and\non/off current ratios of > 1000000 are demonstrated. Individual single-walled\ncarbon nanotubes with diameters ranging from 0.7 nm to 1.1 nm grown from\nstructured catalytic islands using chemical vapor deposition at 700 degree\nCelsius form the channels. Electron beam lithography and a combination of HSQ,\ncalix[6]arene and PMMA e-beam resists were used to structure the short channels\nand source and drain regions. The nanotube transistors display on-currents in\nexcess of 15 microA for drain-source biases of only 0.4 Volt."
    },
    {
        "anchor": "Modeling of Lead Halide Perovskites for Photovoltaic Applications: We report first-principles calculations, using the full potential linear\naugmented plane wave method, on six lead halide semiconductors, namely,\nCH3NH3PbI3, CH3NH3PbBr3, CsPbX3 (X=Cl, Br, I), and RbPbI3. Exchange is modeled\nusing the modified Becke-Johnson potential. With an appropriate choice of the\nparameter that defines this potential, an excellent agreement is obtained\nbetween calculated and experimental band gaps of the six compounds. We comment\non the possibility that the cubic phase of CsPbI3, under hydrostatic pressure,\ncould be a topological insulator.",
        "positive": "Toward III-V/Si co-integration by controlling biatomic steps on\n  hydrogenated Si(001): The integration of III-V on silicon is still a hot topic as it will open up a\nway to co-integrate Si CMOS logic with photonic vices. To reach this aim,\nseveral hurdles should be solved, and more particularly the generation of\nantiphase boundaries (APBs) at the III-V/Si(001) interface. Density functional\ntheory (DFT) has been used to demonstrate the existence of a double-layer steps\non nominal Si(001) which is formed during annealing under proper hydrogen\nchemical potential. This phenomenon could be explained by the formation of\ndimer vacancy lines which could be responsible for the preferential and\nselective etching of one type of step leading to the double step surface\ncreation. To check this hypothesis, different experiments have been carried in\nan industrial 300 mm MOCVD where the total pressure during the anneal step of\nSi(001) surface has been varied. Under optimized conditions, an APBs-free GaAs\nlayer was grown on a nominal Si(001) surface paving the way for III-V\nintegration on silicon industrial platform."
    },
    {
        "anchor": "Influence of spin-orbit coupling on chemical bonding: The influence of spin-orbit interaction on chemical bonds in elemental solids\nand homonuclear dimers is analyzed by means of density-functional-theory\ncalculations. Employing highly precise all-electron full-potential methodology,\nour results represent benchmark quality. Comparison of the scalar- and\nfully-relativistic approaches for elemental solids shows that the spin-orbit\ninteraction may contract or expand the volume of the considered material. The\nlargest variation of the volume is obtained for Au, Tl, I, Bi, Po and Hg,\nexhibiting changes between 1.0--7.6\\%. Using the tight-binding model, we show\nfor diatomic molecules that the nature of this effect lies in the angular\nrearrangement of bonding and antibonding orbitals introduced by spin-orbit\ncoupling. Such an angular rearrangement appears in partially filled $p$- or\n$d$-orbitals in heavy elements. Finally, we discuss the impact of the\nrelativistic effects on the chemical bonding in single-layer iodides and\ntransition metal dichalcogenides",
        "positive": "Theoretical spectroscopy techniques applied to graphene EELS and optics: A thorough understanding of the electronic structure is a necessary first\nstep for the design of nanoelectronics, chemical/bio-sensors, electrocatalysts,\nand nanoplasmonics using graphene. As such, theoretical spectroscopic\ntechniques to describe both direct optical excitations and collective\nexcitations of graphene are of fundamental importance. Starting from density\nfunctional theory (DFT) we use the time dependent linear response within the\nrandom phase approximation (TDDFT-RPA) to describe the loss function\n-Im{{\\epsilon}\\overline{ }^{1}(q,{\\omega})} for graphene. To ensure any\nspurious interactions between layers are neglected, we employ both a radial\ncutoff of the Coulomb kernel, and extra vacuum directly at the TDDFT-RPA level."
    },
    {
        "anchor": "Nature of the magnetic moment of cobalt in ordered FeCo alloy: The magnets are typically classified into Stoner and Heisenberg type,\ndepending on the itinerant or localized nature of the constituent magnetic\nmoments. In this work, we investigate theoretically the behaviour of the\nmagnetic moments of iron and cobalt in their B2-ordered alloy. The results\nbased on local spin density approximation (LSDA) for the density functional\ntheory (DFT) suggest that the Co magnetic moment strongly depends on the\ndirections of the surrounding magnetic moments, which usually indicates the\nStoner-type mechanism of magnetism. This is consistent with the disordered\nlocal moment (DLM) picture of the paramagnetic state, where the magnetic moment\nof cobalt gets substantially suppressed. We argue that this is due to the lack\nof strong on-site electron correlations, which we take into account by\nemploying a combination of DFT and dynamical mean-field theory (DMFT). Within\nLDA+DMFT, we find a substantial quasiparticle mass renormalization and a non\nFermi-liquid behaviour of Fe-$3d$ orbitals. The resulting spectral functions\nare in very good agreement with measured spin-resolved photoemission spectra.\nOur results suggest that local correlations play an essential role in\nstabilizing a robust local moment on Co in the absence of magnetic order at\nhigh temperatures.",
        "positive": "Crystal Structure Prediction via Particle Swarm Optimization: We have developed a powerful method for crystal structure prediction from\n\"scratch\" through particle swarm optimization (PSO) algorithm within the\nevolutionary scheme. PSO technique is dramatically different with the genetic\nalgorithm and has apparently avoided the use of evolution operators (e.g.,\ncrossover and mutation). The approach is based on a highly efficient global\nminimization of free energy surfaces merging total-energy calculations via PSO\ntechnique and requires only chemical compositions for a given compound to\npredict stable or metastable structures at given external conditions (e.g.,\npressure). A particularly devised geometrical structure factor method which\nallows the elimination of similar structures during structure evolution was\nimplemented to enhance the structure search efficiency. The application of\ndesigned variable unit cell size technique has greatly reduced the\ncomputational cost. Moreover, the symmetry constraint imposed in the structure\ngeneration enables the realization of diverse structures, leads to\nsignificantly reduced search space and optimization variables, and thus fastens\nthe global structural convergence. The PSO algorithm has been successfully\napplied to the prediction of many known systems (e.g., elemental, binary and\nternary compounds) with various chemical bonding environments (e.g., metallic,\nionic, and covalent bonding). The remarkable success rate demonstrates the\nreliability of this methodology and illustrates the great promise of PSO as a\nmajor technique on crystal structure determination."
    },
    {
        "anchor": "The interface heterogeneous nucleation and dynamic dispersion of nuclei\n  in solidification process: By comparing the grain sizes under different nucleation conditions, the\ndifferent nucleation mechanisms were investigated. The primitive nuclei origin\nat some specific interface, and subsequently disperse into the bulk melt with\nmelt flow. The survival probability of nuclei decides the nuclei density in\nbulk melt, and the growth of survived nuclei finally constitutes the solidified\ngrains. The nucleation process is highly dynamic, evolving and variable with\nactual experimental condition and production condition.",
        "positive": "Ab initio prediction of Boron compounds arising from Borozene:\n  Structural and electronic properties: Structure and electronic properties of two unusual boron clusters obtained by\nfusion of borozene rings has been studied by means of first principles\ncalculations, based on the generalized-gradient approximation of the density\nfunctional theory, and the semiempirical tight-binding method was used for the\ntransport calculations. The role of disorder has also been considered with\nsingle vacancies and substitutional atoms. Results show that the pure boron\nclusters are topologically planar and characterized by (3c-2e) bonds, which can\nexplain, together with the aromaticity (estimated by means of NICS), the\nremarkable cohesive energy values obtained. Such feature makes these systems\ncompetitive with the most stable boron clusters to date. On the contrary, the\nintroduction of impurities compromises stability and planarity in both cases.\nThe energy gap values indicate that these clusters possess a semiconducting\ncharacter, while when the larger system is considered, zero-values of the\ndensity of states are found exclusively within the HOMO-LUMO gap. Electron\ntransport calculations within the Landauer formalism confirm these indications,\nshowing semiconductor-like low bias differential conductance for these\nstuctures. Differences and similarities with Carbon clusters are highlighted in\nthe discussion."
    },
    {
        "anchor": "Strongly out-of-equilibrium columnar solidification during the Laser\n  Powder-Bed Fusion additive manufacturing process: Laser-based additive manufacturing offers a promising route for 3D printing\nof metallic parts. We evidence experimentally a particular columnar\nsolidification microstructure in a Laser Powder-Bed Fusion processed Inconel\n718 nickel-based alloy, that we interpret using phase-field simulations and\nclassical dendritic growth theories. Owing to the large temperature gradient\nand cooling rate, solidification takes places through dendritic arrays wherein\nthe characteristic length scales, i.e tip radius, diffusion length and primary\nspacing, are of the same order. This leads to a weak mutual interaction between\ndendrite tips, and a drastic reduction of side-branching. The resulting\nirregular cellular-like solidification pattern then remains stable on time\nscales comparable to the complete melt pool solidification, as observed in the\nas-built material.",
        "positive": "Theory of damping in magnetization dynamics, dispelling a myth and\n  pointing a way forward: There is a widely-held belief amongst theoreticians that the Gilbert damping\nparameter {\\alpha} in magnetization dynamics is infinite for a pure metal at\nT=0. The basic error leading to this belief is pointed out explicitly and the\nvarious methods of calculation used are viewed in a unified way based on the\nLorentzian lineshape of ferromagnetic resonance spectra. A general torque\nformula for {\\alpha} is proposed as a good starting-point for treating\ninhomogeneous materials such as alloys, compounds and layered structures. Local\nspin density functional theory provides a simple physical picture, in terms of\na non-uniform precessional cone angle in ferromagnetic resonance, of how such\ninhomogeneity contributes to the damping. In a complementary many-body theory\nthis contribution is given by a vertex correction to the torque-torque response\nfunction."
    },
    {
        "anchor": "Role of charge compensation mechanism on phase formation, dielectric and\n  ferroelectric properties in aliovalent Gd3+ ion modified PbMg1/3Nb2/3O3\n  ceramics: Phase, microstructural, dielectric and ferroelectric properties investigation\nclearly reveal that the charge imbalance created due to alio-valent Gd3+-ion\nsubstitution at Pb2+ site in lead magnesium niobate should be compensated by\nchanging B-site cation ratio instead of creating A-site or B-site vacancies.\nMicrostructure analysis along with elemental mapping exhibit segregation of\nmagnesium oxide (MgO) and gadolinium niobate (GdNbO4) phase, which is observed\nto remain invariant to the charge compensation mechanism. Fitting of frequency\ndependent temperature of dielectric constant maximum Tm (temperature of emax)\nand the Mydosh parameter K calculated from the emax (T) clearly reveals\ncritical slowing down of polar nano-regions (PNRs) dynamics leading to\nsuper-dipolar glass state in Gd3+-ion substituted PMN, when the charge\nimbalance is compensated by creating B-site vacancy or changing B-site cations\nratio. Precipitation of secondary (pyrochlore) phase is resulted in Gd3+-ion\nsubstituted PMN when the charge imbalance is compensated by creating A-site\nvacancies, which causes reduction in interaction among the PNRs and\ncircumventing the super-dipolar glass state.",
        "positive": "Microscopic interface phonon modes in structures of GaAs quantum dots\n  embedded in AlAs shells: By means of a microscopic valence force field model, a series of novel\nmicroscopic interface phonon modes are identified in shell quantum dots(SQDs)\ncomposed of a GaAs quantum dot of nanoscale embedded in an AlAs shell of a few\natomic layers in thickness. In SQDs with such thin shells, the basic principle\nof the continuum dielectric model and the macroscopic dielectric function are\nnot valid any more. The frequencies of these microscopic interface modes lie\ninside the gap between the bulk GaAs band and the bulk AlAs band, contrary to\nthe macroscopic interface phonon modes. The average vibrational energies and\namplitudes of each atomic shell show peaks at the interface between GaAs and\nAlAs. These peaks decay fast as their penetrating depths from the interface\nincrease."
    },
    {
        "anchor": "Designing Fe Nanostructures at Graphene/h-BN Interfaces: Tailor-made magnetic nanostructures offer a variety of functionalities useful\nfor technological applications. In this work, we explore the possibilities of\nrealizing Fe nanostructures at the interfaces of 2D graphene and h-BN by ab\ninitio density functional calculations. With the aid of ab initio\nBorn-Oppenheimer molecular dynamics simulations and diffusion barriers\ncalculated by nudged elastic band method, we find that (i) diffusion barriers\nof Fe on BN are much smaller than those on graphene, (ii) the Fe adatoms form\nclusters within a short time interval (~2.1 ps) and (iii) Fe clusters diffuse\neasily across the C-N interface but become immobile at the C-B interface. The\ncalculated magnetic exchange coupling between Fe clusters at C-B interfaces\nvaries non-monotonically as a function of the width of BN separating the\ngraphene parts. One may envisage design of magnetic nanostructures at the C-B\ninterface of 2D graphene/h-BN hybrids to realize interesting applications\nrelated to spintronics.",
        "positive": "Element-selective tracking ultrafast demagnetization process in Co/Pt\n  multilayer thin films by the resonant magneto-optical Kerr effect: We examined the photo-induced dynamics of ferromagnetic Co/Pt thin films\ndemonstrating perpendicular magnetic anisotropy with element specificity using\nresonant polar magneto-optical Kerr effect measurements at Pt~N${}_{6,7}$ and\nCo~M${}_{2,3}$ edges with an x-ray free electron laser. The obtained results\nshowed a clear element dependence of photo-induced demagnetization time scales:\n$\\tau_\\textrm{demag.}^\\textrm{Co}=80\\pm60~\\textrm{fs}$ and\n$\\tau_\\textrm{demag.}^\\textrm{Pt}=640\\pm140~\\textrm{fs}$. This dependence is\nexplained by the induced moment of the Pt atom by current flow from the Co\nlayer through the interfaces. The observed magnetization dynamics of Co and Pt\ncan be attributed to the characteristics of photo-induced Co/Pt thin film\nphenomena including all-optical switching."
    },
    {
        "anchor": "Three-dimensional real Chern insulator in bulk $\u03b3$-graphyne: The real Chern insulator state, featuring nontrivial real Chern number and\nsecond-order boundary modes, has been revealed in a few two-dimensional\nsystems. The concept can be extended to three dimensions (3D), but a proper\nmaterial realization is still lacking. Here, based on first-principles\ncalculations and theoretical analysis, we identify the recently synthesized\nbulk ${\\gamma}$-graphyne as a 3D real Chern insulator. Its nontrivial bulk\ntopology leads to topological hinge modes spreading across the 1D edge\nBrillouin zone. Under compression of the interlayer distance, the system can\nundergo a topological phase transition into a real nodal-line semimetal, which\nhosts three bulk nodal rings and topological boundary modes on both surfaces\nand hinges. We also develop a minimal model which captures essential physics of\nthe system.",
        "positive": "Electronic structure and band parameters for ZnX (X = O, S, Se, Te): First-principles density-functional calculations have been performed for zinc\nmonochalcogenides with zinc-blende- and wurtzite-type structures. It is shown\nthat the local-density approximation underestimates the band gap, misplaces the\nenergy levels of the Zn-3d states, and overestimates the crystal-field\nsplitting energy. Without spinorbit coupling, the order of the states at the\ntop of VB is found to be normal for all the ZnX phases considered. Upon\ninclusion of the spinorbit coupling in calculations, ZnO in zinc-blende- and\nwurtzite-type phases become anomalous. It is shown that the Zn-3d electrons are\nresponsible for the anomalous order. The effective masses of electrons and\nholes have been calculated and found that holes are much anisotropic and\nheavier than the electrons in agreement with experimental findings. The typical\nerrors in calculated band gaps and related parameters originate from strong\nCoulomb correlations, which are found to be highly significant in ZnO. The\nLDA+U approach is found to correct the strong correlation of the Zn-3d\nelectrons, and thus improves the agreement with the experimentally established\nlocation of the Zn-3d levels. Consequently, it increases significantly the\nparameters underestimated in the pure LDA calculations."
    },
    {
        "anchor": "Ab initio approach to the elastic, electronic, and optical properties of\n  MoTe2: A topological Weyl semimetal: The topological Weyl semimetal MoTe2, in the orthorhombic phase, is an\nimportant system both from the point of view of fundamental physics and\npotential applications. In this study we have investigated the elastic,\nelectronic, bonding and optical properties of MoTe2 using density functional\ntheory. Study of the elastic constants and moduli indicates that MoTe2 is a\nrelatively soft material with high level of machinability. Mechanical stability\nconditions are fulfilled. The compound possesses elastic and mechanical\nanisotropy and is prone to brittle fracture. Elastic parameters indicate that\nboth covalent and metallic bondings are present in MoTe2. This is supported by\nthe charge density distribution mapping and Mulliken and Hirshfeld bond\npopulation analyses. Debye temperature has been calculated. A relatively low\nvalue of Debye temperature also supports the scenario where bonding strengths\nare weak. The bulk electronic band structure calculations reveal clear\nindications of semi-metallic character. A pseudogap in the electronic energy\ndensity of states at the Fermi level indicates high level of electronic\nstability. Features reminiscent of the Dirac cone is observed close to the\nFermi level. There is significant electronic anisotropy. Bands running in the\ncrystallographic c-direction are non-dispersive with high carrier effective\nmass. Investigation of optical constants demonstrate that MoTe2 possess\nexcellent reflecting characteristics over a wide spectral range encompassing\nthe infrared to ultraviolet regions. The compound also has high refractive\nindex in the visible range. MoTe2 is optically anisotropic, reflecting the\nanisotropic nature of the electronic band structure. The energy dependent\noptical parameters show metallic features and are in complete accord with the\nelectronic density of states calculations.",
        "positive": "Electronic Structure, Local Moments and Transport in Fe_2VAl: Local spin density approximation calculations are used to elucidate\nelectronic and magnetic properties of Heusler structure Fe_2VAl. The compound\nis found to be a low carrier density semimetal. The Fermi surface has small\nhole pockets derived from a triply degenerate Fe derived state at Gamma\ncompensated by an V derived electron pocket at the X point. The ideal compound\nis found to be stable against ferromagnetism. Fe impurities on V sites,\nhowever, behave as local moments. Because of the separation of the hole and\nelectron pockets the RKKY interaction between such local moments should be\nrapidly oscillating on the scale of its decay, leading to the likelihood of\nspin-glass behavior for moderate concentrations of Fe on V sites. These\nfeatures are discussed in relation to experimental observations of an unusual\ninsulating state in this compound."
    },
    {
        "anchor": "$\\mathrm{Co_2Fe_{1-x}Cr_xSi}$ Heusler Alloys : A promising material for\n  spintronics application: In this article, we investigated the effect of Cr substitution in place of Fe\non the structural, magnetic and transport properties of $\\mathrm{Co_2FeSi}$\nalloy. A comprehensive structural analysis is done using X-ray diffraction\n(XRD) and extended X-ray absorption fine structure (EXAFS) spectroscopy.\nQuaternary Heusler compounds $\\mathrm{Co_2Fe_{1-x}Cr_xSi}$ with Cr content (x =\n0.1, 0.3, 0.5) were found to crystallize in cubic structure. The synchrotron\nbased EXAFS studies reveal that the anti-site disorder increases with the\nincrease in Cr concentration. The saturation magnetization values in all the\nalloys are found to be less than those expected from the Slater-Pauling rule,\nwhich may be due to the some inherent disorder. A detailed resistivity analysis\nin the temperature range of 5-300 K is done, taking into account different\nscattering mechanisms. The residual resistivity ratio is found to decrease with\nincreasing Cr concentration. A disorder induced resistivity minimum due to weak\nlocalization effect is seen for x = 0.5. The resistivity measurements also\nindicate that the half-metallic character survives upto 100 K for x = 0.1,\nwhereas the alloys with x= 0.3 and 0.5 show signature of half- metallic nature\neven at higher temperatures. First principles calculation done with a more\nrobust exchange correlation functional (namely HSE-06) confirms the half\nmetallicity in the entire concentration range. Theoretically simulated band gap\nand magnetic moments compliment the experimental findings and are compared\nwherever possible. All these properties make $\\mathrm{Co_2Fe_{1-x}Cr_xSi}$ a\npromising material for spintronics application.",
        "positive": "Charge density wave melting in one-dimensional wires with femtosecond\n  sub-gap excitation: Charge density waves (CDWs) are symmetry-broken ground states that commonly\noccur in low-dimensional metals due to strong electron-electron and/or\nelectron-phonon coupling. The non-equilibrium carrier distribution established\nvia photodoping with femtosecond laser pulses readily quenches these ground\nstates and induces an ultrafast insulator-to-metal phase transition. To date,\nCDW melting has been mainly investigated in the single-photon and tunneling\nregimes, while the intermediate multi-photon regime has received little\nattention. Here we excite one-dimensional indium wires with a CDW gap of\n~300meV with mid-infrared pulses at 190meV with MV/cm field strength and probe\nthe transient electronic structure with time- and angle-resolved photoemission\nspectroscopy (tr-ARPES). We find that the CDW gap is filled on a timescale\nshort compared to our temporal resolution of 300fs and that the phase\ntransition is completed within ~1ps. Supported by a minimal theoretical model\nwe attribute our findings to multi-photon absorption across the CDW gap."
    },
    {
        "anchor": "$zT$-factor enhancement in SnSe: predictions from first principles\n  calculations: The electronic structure and thermoelectric properties of SnSe are studied by\nfirst-principles methods. The inclusion of van der Waals dispersive corrections\nimproves the agreement of structural parameters with experiments. The bands\nstructure and projected density of states justify the macroscopic anisotropy\nexhibited by this system. An original methodology is used to estimate the\nchemical potential and the relaxation time for the electrical and thermal\nconductivities. Following this methodology, the Seebeck coefficient and thermal\nconductivity for single crystals and polycrystals are described in good\nagreement with experimental data. As for the electrical conductivity, values\ncalculated with a temperature-dependent relaxation time compare well with\navailable measurements, especially for single crystals, polycrystals are better\ndescribed by a constant relaxation time. Finally, the figure of merit of SnSe\nsingle crystals and polycrystals is calculated. It is found to exhibit a\nmaximum for some \"ideal\" carrier concentration, and might be noticeably\nenhanced by using carrier concentrations higher than the experimental ones.\nFrom these findings, possible strategies to increase the figure of merit in\npractise are suggested.",
        "positive": "Surface phonons in two-layer thin films of GeSe: This paper presents ab inition calculations of the surface phonon spectra of\nGeSe layered semiconductor compound, based on the Density Functional\nPerturbation Theory (DFPT). The surface has been imitated by a structure of\nperiodically arranged slabs of two layers of GeSe crystal separated from other\nidentical layers by the layers of vacuum sufficiently wide to ignore the effect\nof the upper boundary of the double-layer upon its lower boundary. We discuss\nthe character of the surface modes located in the gaps, in the pockets, and in\nthe area of allowed phonon states for the bulk GeSe crystals, as well as\noutside (above and below) the boundaries of the bulk phonon states."
    },
    {
        "anchor": "Tunable magnetism of a single-carbon vacancy in graphene: Removing a single-carbon vacancy introduces (quasi-)localized states for both\nand electrons in graphene. Interactions between the localized dangling bond and\nquasilocalized electrons of a single-carbon vacancy in graphene are predicted\nto control its magnetism. However, experimentally confirming this prediction\nthrough manipulating the interactions between the and electrons remains an\noutstanding challenge. Here we report the manipulation of magnetism of\nindividual single-carbon vacancy in graphene by using a scanning tunnelling\nmicroscopy (STM) tip. Our spin-polarized STM measurements, complemented by\ndensity functional theory calculations, indicate that interactions between the\nlocalized and quasilocalized electrons could split the electrons into two\nstates with opposite spins even when they are well above the Fermi level. Via\nthe STM tip, we successfully manipulate both the magnitude and direction of\nmagnetic moment of the electrons with respect to that of the electrons. Three\ndifferent magnetic states of the single-carbon vacancy, exhibiting magnetic\nmoments of about 1.6, 0.5, and 0 respectively, are realized in our experiment.",
        "positive": "Ab initio investigation of Fe$^{2+}$/Fe$^{3+}$ dimerization and\n  ferroelectricity in multiferroic magnetite: role of electronic correlations: Based on ab initio density functional theory, we have investigated a\nmicroscopic mechanism that leads to Fe$^{2+}_{B}$/Fe$^{3+}_{B}$ dimerization\nand consequent ferroelectricity in charge ordered Fe$_{3}$O$_{4}$ with $P2$\nsymmetry. In addition to the simple inter-site Coulomb repulsion, quantum\nhybridization effects are invoked to explain the Fe$^{2+}_{B}$/Fe$^{3+}_{B}$\nbond dimerization. Our results, based on the generalized gradient approximation\n+ Hubbard $U$ (GGA+$U$) method, indicate that noncentrosymmetric $P2$ magnetite\nshows a finite and sizeable ferroelectric polarization along the $b$\ncrystalline axis. From the $U$ dependence of polarization, we conclude that the\norigin of ferroelectricity in $P2$ Fe$_{3}$O$_{4}$ lies in the recently\nproposed \"intermediate site/bond-centered charge ordering\"."
    },
    {
        "anchor": "Universal scaling for the spin-electricity conversion on surface states\n  of topological insulators: We have investigated spin-electricity conversion on surface states of\nbulk-insulating topological insulator (TI) materials using a spin pumping\ntechnique. The sample structure is Ni-Fe|Cu|TI trilayers, in which magnetic\nproximity effects on the TI surfaces are negligibly small owing to the inserted\nCu layer. Voltage signals produced by the spin-electricity conversion are\nclearly observed, and enhanced with decreasing temperature in line with the\ndominated surface transport at lower temperatures. The efficiency of the\nspin-electricity conversion is greater for TI samples with higher resistivity\nof bulk states and longer mean free path of surface states, consistent with the\nsurface spin-electricity conversion.",
        "positive": "The role of dwell hold on the dislocation mechanisms of fatigue in a\n  near alpha titanium alloy: The dislocation structures appearing in highly mis-oriented soft/hard grain\npairs in near-alpha titanium alloy Ti6242Si were examined with and without the\napplication of load holds (dwell) during fatigue. Dislocation pile-up in a soft\ngrain resulted in internal stresses in an adjacent hard grain which could be\nrelaxed by dislocation multiplication at localized Frank-Read sources, a\nprocess assisted by the provision of a relaxation time during a load hold. The\nrate of this process is suggested to be controlled by <c+a> pyramidal\ncross-slip and <a> basal junction formation. A high density of <a> prism\npile-ups is observed by dual slip, together with the nucleation of edge\ndislocations in the soft grain of a highly mis-oriented grain pair, increasing\nthe possibility of cracking. The stress concentration developed by such\npile-ups is found to be higher in dwell fatigue (single-ended pile-ups) than in\nLCF (double ended). Analytical modelling shows that the maximum normal stress\nproduced on the hard grain in dwell fatigue by this pile-up would be\nnear-basal, ~2.5 degree to (0002). This provides support for the dominant\nhypothesis for the rationalisation of dwell fatigue crack nucleation in Ti\nalloys, which derives from the Stroh pile-up model, and elaboration of the\nunderlying dislocation phenomena that result from load shedding and lead to\nbasal faceting."
    },
    {
        "anchor": "PANIC: a 3D dislocation dynamics model for climb and glide in epitaxial\n  films and heterostructures: This paper presents PANIC, a 3D discrete mesoscale dislocation dynamics model\nwhich includes a fully quantitative treatment of both dislocation climb and\ndislocation glide, including climb driven by both osmotic and mechanical\nstresses and climb enabled by both bulk and pipe diffusion, including full\nelastic anisotropy for materials with hexagonal symmetry. Efficient\ncalculations can be performed for epitaxial thin films, multilayers and device\nstructures with free surfaces, including those with irregular geometries (e.g.\nislands). The model also includes the capability to simulate dislocation\ndynamics during the growth of the thin films or heterostructures. The model has\nbeen validated against experiment for thin films of GaN, AlN and AlGaN but is\nwidely applicable to other material systems, both hexagonal and cubic.",
        "positive": "Aluminum doping improves the energetics of lithium, sodium, and\n  magnesium storage in silicon: While Si is an effective insertion type anode for Li-ion batteries,\ncrystalline Si has been shown to be unsuitable for Na and Mg storage due, in\nparticular, to insufficient binding strength. It has recently been reported\nthat Si nanowires could be synthesized with high-concentration (several atomic\n%) and dispersed Al doping. Here we show based on density functional theory\ncalculations that Al doping significantly improves the energetics for Na and Mg\ninsertion, specifically, making it thermodynamically favored versus vacuum\nreference states. For high Al concentrations, the energy of Mg in Al-doped Si\napproaches the cohesive energy of Mg. However, the migration barriers for the\ndiffusion of Li (0.57-0.70 eV), Na (1.07-1.19 eV) and Mg (0.97-1.18 eV) in\nAl-doped Si are found to remain about as high as in pure Si, likely preventing\neffective electrochemical sodiation and magnesiation."
    },
    {
        "anchor": "Ab initio thermodynamic model of Cu$_2$ZnSnS$_4$: Thin-film solar cells based on the semiconductor Cu$_2$ZnSnS$_4$ (CZTS) are a\npromising candidate for Terawatt-scale renewable energy generation. While CZTS\nis composed of earth abundant and non-toxic elements, arranged in the kesterite\ncrystal structure, there is a synthetic challenge to produce high-quality\nstoichiometric materials over large areas. We calculate the thermodynamic\npotentials of CZTS and its elemental and binary components based on energetic\nand vibrational data computed using density functional theory. These chemical\npotentials are combined to produce a thermodynamic model for the stability of\nCZTS under arbitrary temperatures and pressures, which provide insights into\nthe materials chemistry. CZTS was shown to be thermodynamically stable with\nrespect to its component elements and their major binary phases binaries under\nmodest partial pressure of sulfur and temperatures below 1100K. Under\nnear-vacuum conditions with sulfur partial pressures below 1 Pa decomposition\ninto binaries including solid SnS becomes favourable, with a strongly\ntemperature-dependent stability window.",
        "positive": "57Fe Mossbauer study of Lu2Fe3Si5 iron silicide superconductor: With the advent of Fe-As based superconductivity it has become important to\nstudy how superconductivity manifests itself in details of 57Fe Mossbauer\nspectroscopy of conventional, Fe - bearing superconductors. To this end, the\niron-based superconductor Lu2Fe3Si5 has been studied by 57Fe Mossbauer\nspectroscopy over the temperature range from 4.4 K to room temperature with\nparticular attention to the region close to the superconducting transition\ntemperature (Tc = 6.1 K). Consistent with the two crystallographic sites for Fe\nin this structure, the observed spectra appear to have a pattern consisting of\ntwo doublets over the whole temperature range. The value of Debye temperature\nwas estimated from temperature dependence of the isomer shift and the total\nspectral area and compared with the specific heat capacity data. Neither\nabnormal behavior of the hyperfine parameters at or near Tc, nor phonon\nsoftening were observed."
    },
    {
        "anchor": "Micro-Raman Spectroscopy of Mechanically Exfoliated Few-Quintuple Layers\n  of Bi(2)Te(3), Bi(2)Se(3) and Sb(2)Te(3) Materials: Bismuth telluride - Bi(2)Te(3)- and related compounds have recently attracted\nstrong interest owing to the discovery of the topological insulator properties\nin many members of this family of materials. The few-quintuple films of these\nmaterials are particularly interesting from the physics point of view. We\nreport results of the micro-Raman spectroscopy study of the \"graphene-like\"\nexfoliated few-quintuple layers of Bi(2)Te(3), Bi(2)Se(3) and Sb(2)Te(3). It is\nfound that crystal symmetry breaking in few-quintuple films results in\nappearance of A1u-symmetry Raman peaks, which are not active in the bulk\ncrystals. The scattering spectra measured under the 633-nm wavelength\nexcitation reveals a number of resonant features, which could be used for\nanalysis of the electronic and phonon processes in these materials. In order to\nelucidate the influence of substrates on the few-quintuple-thick topological\ninsulators we examined the Raman spectra of these films placed on mica,\nsapphire and hafnium-oxide substrates. The obtained results help to understand\nthe physical mechanisms of Raman scattering in the few-quintuple-thick films\nand can be used for nanometrology of topological insulator films on various\nsubstrates.",
        "positive": "Mixed Valence Pseudobrookite Al$_{1.75}$Ti$_{1.25}$O$_5$: High\n  Temperature Phase Transitions, Magnetism and Resistivity: Dark blue single crystals of Al$_{1.75}^{3+}$ Ti$_{1.0}^{4+}$\nTi$_{0.25}^{3+}$O$_5$ were grown with a novel synthesis method based on the\nreaction of a Ti3+/Ti4+ containing langbeinite melt and Al$_2$O$_3$. The\nobtained needles crystallize in the pseudobrookite structure and undergo two\nreversible phase transitions from orthorhombic Cmcm to C2/m first and\nsubsequently to C2 symmetry. Like the known aluminum titanate pseudobrookites,\nanistropic thermal expansion is observed. The temperature evolution of the\ncrystal structure reveals some insights into the mechanism leading to the\ndecomposition of the Al$_{1.75}$Ti$_{1.25}$O$_5$ above 725$^\\circ$C. The\nmagnetic and electrical properties are discussed and compared to other reported\naluminum titanate pseudobrookites."
    },
    {
        "anchor": "Temperature-dependent elastic properties of binary and multicomponent\n  high-entropy refractory carbides: Available information concerning the elastic moduli of refractory carbides at\ntemperatures (T) of relevance for practical applications is sparse and/or\ninconsistent. We carry out ab initio molecular dynamics (AIMD) simulations at T\n= 300, 600, 900, and 1200 K to determine the temperature-dependences of the\nelastic constants of rocksalt-structure (B1) TiC, ZrC, HfC, VC, and TaC\ncompounds as well as multicomponent high-entropy carbides (Ti,Zr,Hf,Ta,W)C and\n(V,Nb,Ta,Mo,W)C. The second order elastic constants are calculated by\nleast-square fitting of the analytical expressions of stress vs. strain\nrelationships to simulation results obtained from three tensile and three shear\ndeformation modes. Moreover, we employ sound velocity measurements to evaluate\nthe bulk, shear, elastic moduli and Poisson's ratios of single-phase B1\n(Ti,Zr,Hf,Ta,W)C and (V,Nb,Ta,Mo,W)C at ambient conditions. Our experimental\nresults are in excellent agreement with the values obtained by AIMD\nsimulations. In comparison with the predictions of previous ab initio\ncalculations - where the extrapolation of finite-temperature elastic properties\naccounted for thermal expansion while neglecting intrinsic vibrational effects\n- AIMD simulations produce a softening of elastic moduli with T in closer\nagreement with experiments. Results of our simulations show that TaC is the\nsystem which exhibits the highest elastic resistances to both tensile and shear\ndeformation up to 1200 K, and identify the high-entropy (V,Nb,Ta,Mo,W)C system\nas candidate for applications that require good ductility and toughness at room\nas well as elevated temperatures.",
        "positive": "High Temperature Far Infrared Dynamics of Orthorhombic NdMnO3:\n  Emissivity and Reflectivity: We report on near normal far- and mid-infrared emission and reflectivity of\nNdMnO3 perovskite from room temperature to sample decomposition above 1800 K.\nAt 300 K the number infrared active phonons is in close agreement with the 25\ncalculated for the orthorhombic D2h16-Pbnm (Z=4) space group. Their number\ngradually decreases as we approach the temperature of orbital disorder at ~1023\nK where the orthorhombic O' lower temperature cooperative phase coexists with\nthe cubic orthorhombic O. At above ~1200 K, the three infrared active phonons\ncoincide with the expected for cubic Pm-3m (Z=1) in the high temperature\ninsulating regime. Heating samples in dry air triggers double exchange\nconductivity by Mn3+ and Mn4+ ions and a small polaron mid-infrared band. Fits\nto the optical conductivity single out the octahedral antisymmetric and\nsymmetric vibrational modes as main phonons in the electron-phonon interactions\nat 875 K. For 1745 K, it is enough to consider the symmetric stretching\ninternal mode. An overdamped defect induced Drude component is clearly outlined\nat the highest temperatures. We conclude that Rare Earth manganites eg\nelectrons are prone to spin, charge, orbital, and lattice couplings in an\nintrinsic orbital distorted perovskite lattice favoring embryonic low energy\ncollective excitations."
    },
    {
        "anchor": "From Strong to Weak Coupling Regime in a Single GaN Microwire up to Room\n  Temperature: Large bandgap semiconductor microwires constitute a very advantageous\nalternative to planar microcavities in the context of room temperature strong\ncoupling regime between exciton and light. In this work we demonstrate that in\na GaN microwire, the strong coupling regime is achieved up to room temperature\nwith a large Rabi splitting of 125 meV never achieved before in a Nitride-based\nphotonic nanostructure. The demonstration relies on a method which doesn't\nrequire any knowledge \\'a priori on the photonic eigenmodes energy in the\nmicrowire, i.e. the details of the microwire cross-section shape. Moreover,\nusing a heavily doped segment within the same microwire, we confirm\nexperimentally that free excitons provide the oscillator strength for this\nstrong coupling regime. The measured Rabi splitting to linewidth ratio of 15\nmatches state of the art planar Nitride-based microcavities, in spite of a much\nsimpler design and a less demanding fabrication process. These results show\nthat GaN microwires constitute a simpler and promising system to achieve\nelectrically pumped lasing in the strong coupling regime.",
        "positive": "Nanoindentation of Porous Bulk and Thin Films of LSCF: In this paper we show how reliable measurements on porous ceramic films can\nbe made by appropriate nanoindentation experiments and analysis.\nRoom-temperature mechanical properties of the mixed-conducting perovskite\nmaterial LSCF6428 were investigated by nanoindentation of porous bulk samples\nand porous films sintered at temperatures from 900-1200C. A spherical indenter\nwas used so that the contact area was much greater than the scale of the porous\nmicrostructure. The elastic modulus of the bulk samples was found to increase\nfrom 33.8-174.3 GPa and hardness from 0.64-5.32 GPa as the porosity decreased\nfrom 45-5% after sintering at 900-1200C. Densification under the indenter was\nfound to have little influence on the measured elastic modulus. The residual\nporosity in the dense sample was found to account for the discrepancy between\nthe elastic moduli measured by indentation and by impulse excitation.\nCrack-free LSCF6428 films of acceptable surface roughness for indentation were\nalso prepared by sintering at 900-1200C. Reliable measurements of the true\nproperties of the films were obtained by data extrapolation provided that the\nratio of indentation depth to film thickness was in the range 0.1 to 0.2. The\nelastic moduli of the films and bulk materials were approximately equal for a\ngiven porosity. The 3D microstructures of films before and after indentation\nwere characterized using FIB-SEM tomography. Finite element modelling of the\nelastic deformation of the actual microstructures showed excellent agreement\nwith the nanoindentation results."
    },
    {
        "anchor": "Operando imaging of all-electric spin texture manipulation in\n  ferroelectric and multiferroic Rashba semiconductors: The control of the electron spin by external means is a key issue for\nspintronic devices. Using spin- and angle-resolved photoemission spectroscopy\n(SARPES) with three-dimensional spin detection, we demonstrate operando\nelectrostatic spin manipulation in ferroelectric GeTe and multiferroic\nGe1-xMnxTe. We not only demonstrate for the first time electrostatic spin\nmanipulation in Rashba semiconductors due to ferroelectric polarization\nreversal, but are also able to follow the switching pathway in detail, and show\na gain of the Rashba-splitting strength under external fields. In multiferroic\nGe1-xMnxTe operando SARPES reveals switching of the perpendicular spin\ncomponent due to electric field induced magnetization reversal. This provides\nfirm evidence of effective multiferroic coupling which opens up magnetoelectric\nfunctionality with a multitude of spin-switching paths in which the magnetic\nand electric order parameters are coupled through ferroelastic relaxation\npaths. This work thus provides a new type of magnetoelectric switching\nentangled with Rashba-Zeeman splitting in a multiferroic system.",
        "positive": "A scaling relation of anomalous Hall effect in ferromagnetic\n  semiconductors and metals: A scaling relation of the anomalous Hall effect recently found in a\nferromagnetic semiconductor (Ti,Co)O_2_ is compared with those of various\nferromagnetic semiconductors and metals. Many of these compounds with\nrelatively low conductivity sigma_xx_ < 10^4 ohm^-1 cm^-1 are also found to\nexhibit similar relation: anomalous Hall conductivity sigma_AH_ approximately\nscales as sigma_AH_ proportional to sigma_xx_^1.6, that is coincident with a\nrecent theory. This relation is valid over five decades of sigma_xx_\nirrespective of metallic or hopping conduction."
    },
    {
        "anchor": "Discrete averaging relations for micro to macro transition: The well-known Hill's averaging theorems for stresses and strains as well as\nthe so-called Hill-Mandel principle of macrohomogeneity are essential\ningredients for the coupling and the consistency between the micro and macro\nscales in multiscale finite element procedures (FE$^2$). We show in this paper\nthat these averaging relations hold exactly under standard finite element\ndiscretizations, even if the stress field is discontinuous across elements and\nthe standard proofs based on the divergence theorem are no longer suitable. The\ndiscrete averaging results are derived for the three classical types of\nboundary conditions (affine displacement, periodic and uniform traction\nboundary conditions) using the properties of the shape functions and the weak\nform of the microscopic equilibrium equations. The analytical proofs are\nfurther verified numerically through a simple finite element simulation of an\nirregular representative volume element undergoing large deformations.\nFurthermore, the proofs are extended to include the effects of body forces and\ninertia, and the results are consistent with those in the smooth continuum\nsetting. This work provides a solid foundation to apply Hill's averaging\nrelations in multiscale finite element methods without introducing an\nadditional error in the scale transition due to the discretization.",
        "positive": "Closed-loop Error Correction Learning Accelerates Experimental Discovery\n  of Thermoelectric Materials: The exploration of thermoelectric materials is challenging considering the\nlarge materials space, combined with added exponential degrees of freedom\ncoming from doping and the diversity of synthetic pathways. Here we seek to\nincorporate historical data and update and refine it using experimental\nfeedback by employing error-correction learning (ECL). We thus learn from prior\ndatasets and then adapt the model to differences in synthesis and\ncharacterization that are otherwise difficult to parameterize. We then apply\nthis strategy to discovering thermoelectric materials where we prioritize\nsynthesis at temperatures < 300{\\deg}C. We document a previously unreported\nchemical family of thermoelectric materials, PbSe:SnSb, finding that the best\ncandidate in this chemical family, 2 wt% SnSb doped PbSe, exhibits a power\nfactor more than 2x that of PbSe. Our investigations show that our closed-loop\nexperimentation strategy reduces the required number of experiments to find an\noptimized material by as much as 3x compared to high-throughput searches\npowered by state-of-the-art machine learning models. We also observe that this\nimprovement is dependent on the accuracy of prior in a manner that exhibits\ndiminishing returns, and after a certain accuracy is reached, it is factors\nassociated with experimental pathways that dictate the trends."
    },
    {
        "anchor": "Depth dependant element analysis of PbMg$_{1/3}$Nb$_{2/3}$O$_{3}$ using\n  muonic X-rays: The relaxor PbMg$_{1/3}$Nb$_{2/3}$O$_{3}$ (PMN) has received attention due to\nits potential applications as a piezoelectric when doped with PbTiO$_{3}$ (PT).\nPrevious results have found that there are two phases existing in the system,\none linked to the near-surface regions of the sample, the other in the bulk.\nHowever, the exact origin of these two phases is unclear. In this paper, depth\ndependant analysis results from negative muon implantation experiments are\npresented. It is shown that the Pb content is constant throughout all depths\nprobed in the sample, but the Mg and Nb content changes in the near-surface\nregion below 100$\\mu$m. At a implantation depth of 60$\\mu$m, it is found that\nthere is a 25% increase in Mg content, with a simultaneous 5% decrease in Nb\ncontent in order to maintain charge neutrality. These results show that the\npreviously observed skin effects in PMN are due to a change in concentration\nand unit cell.",
        "positive": "qeirreps: an open-source program for Quantum ESPRESSO to compute\n  irreducible representations of Bloch wavefunctions: Bloch wavefunctions in solids form a representation of crystalline\nsymmetries. Recent studies revealed that symmetry representations in band\nstructure can be used to diagnose the topological properties of weakly\ninteracting materials. In this work, we introduce an open-source program\nqeirreps that computes the representation characters in a band structure based\non the output file of Quantum ESPRESSO. Our program also calculates the Z4\nindex, i.e., the sum of inversion parities at all time-reversal invariant\nmomenta, for materials with inversion symmetry. When combined with the symmetry\nindicator method, this program can be used to explore new topological\nmaterials."
    },
    {
        "anchor": "Very large Magneto-impedance and its scaling behavior in amorphous\n  Fe73.5Nb3Cu1Si13.5B9 ribbon: Magneto-impedance (MI) effects have been observed for amorphous\nFe73.5Nb3Cu1Si13.5B9 ribbon which has been excited by an a.c. magnetic field\nparallel to the length of the ribbon. Maximum relative change in MI as large as\n-99% was observed which has never been reported before. The relative change in\nMI, when plotted against scaled field was found to be nearly frequency\nindependent. A phenomenological formula for magneto-impedance, Z(H), in a\nferromagnetic material, is proposed based on Pade approximant to describe the\nscaled behavior of MI.",
        "positive": "Exchange bias in Co/CoO core-shell nanowires: Role of the\n  antiferromagnetic superparamagnetic fluctuations: The magnetic properties of Co (<D>=15 nm, <L>=130nm) nanowires are reported.\nIn oxidized wires, we measure large exchange bias fields of the order of 0.1 T\nbelow T ~ 100 K. The onset of the exchange bias, between the ferromagnetic core\nand the anti-ferromagnetic CoO shell, is accompanied by a coercivity drop of\n0.2 T which leads to a minimum in coercivity at $\\sim100$ K. Magnetization\nrelaxation measurements show a temperature dependence of the magnetic viscosity\nS which is consistent with a volume distribution of the CoO grains at the\nsurface. We propose that the superparamagnetic fluctuations of the\nanti-ferromagnetic CoO shell play a key role in the flipping of the nanowire\nmagnetization and explain the coercivity drop. This is supported by\nmicromagnetic simulations. This behavior is specific to the geometry of a 1D\nsystem which possesses a large shape anisotropy and was not previously observed\nin 0D (spheres) or 2D (thin films) systems which have a high degree of symmetry\nand low coercivities. This study underlines the importance of the AFM\nsuper-paramagnetic fluctuations in the exchange bias mechanism."
    },
    {
        "anchor": "Suppressed carrier density for the patterned high mobility\n  two-dimensional electron gas at gamma-Al2O3/SrTiO3 heterointerfaces: The two-dimensional electron gas (2DEG) at the non-isostructural interface\nbetween spinel gamma-Al2O3 and perovskite SrTiO3 is featured by a record\nelectron mobility among complex oxide interfaces in addition to a high carrier\ndensity up to the order of 1E15 cm-2. Herein, we report on the patterning of\n2DEG at the gamma-Al2O3/SrTiO3 interface grown at 650 {\\deg}C by pulsed laser\ndeposition using a hard mask of LaMnO3. The patterned 2DEG exhibits a critical\nthickness of 2 unit cells of gamma-Al2O3 for the occurrence of interface\nconductivity, similar to the unpatterned sample. However, its maximum carrier\ndensity is found to be approximately 3E13 cm-2, much lower than that of the\nunpatterned sample (1E15 cm-2). Remarkably, a high electron mobility of\napproximately 3,600 cm2V-1s-1 was obtained at low temperatures for the\npatterned 2DEG at a carrier density of 7E12 cm-2, which exhibits clear\nShubnikov-de Hass quantum oscillations. The patterned high-mobility 2DEG at the\ngamma-Al2O3/SrTiO3 interface paves the way for the design and application of\nspinel/perovskite interfaces for high-mobility all-oxide electronic devices.",
        "positive": "Electron pair emission from surfaces: Some general experimental\n  considerations: We discuss some experimental facets of electron pair emission from surfaces\nusing two different experimental approaches. In the first case the instrument\nconsists of a pair of hemispherical analyzers which are operated with\ncontinuous primary beams of electrons or photons. The second instrument employs\na pair of time-of-flight spectrometers which require a pulsed excitation\nsource. A key experimental quantity is the ratio of `true' to `random'\ncoincidences which can be determined in different ways. Regardless of the type\nof instrument the primary flux has to adopt a much smaller value than in single\nelectron spectroscopy. We describe different approaches to obtain the relevant\ncount rates, in particular the concept of operating with a delayed coincidence\ncircuit. We also address the question on how to compare the two types of\nspectrometer in terms of their performance."
    },
    {
        "anchor": "Observation of a possible diluted ferromagnetism above room temperature\n  in cobalt-substituted LaTa(O,N)3-d: Since 2000, the intensive effort in materials research to develop a diluted\nmagnetic semiconductor exhibiting high-temperature (HT) ferromagnetism above\nroom temperature was not successful. Here, the possible first bulk diluted\nHT-ferromagnetic non-metallic materials, based on the perovskite-type\noxynitrides LaTa1-xCox(O,N)3-d (x = 0.01, 0.03, 0.05) are realized. The Curie\ntemperature of the synthesized powders exceeds 600 K and the sample\nmagnetizations are large enough to be directly attracted by permanent magnets.\nCobalt clusters as a possible source for the observed HT-ferromagnetism can be\nexcluded, since all applied characterization methods verify phase purity.\nApplied conventional and element-specific magnetometry imply ferromagnetic\nintermediate spin (IS) Co3+ which is included in a ferromagnetic host matrix.\nThis indicates a complex magnetic interplay between the existing crystal\nstructure, the observed anionic vacancies, and the introduced cobalt ions.\nThese results lay the foundation for the experimental investigation and design\nof further diluted HT-ferromagnetic semiconductors.",
        "positive": "Effect of Sr doping on the magnetic exchange interactions in manganites: Strontium doping transforms manganites of type La(1-x)Sr(x)MnO(3) from an\ninsulating antiferromagnet (x=0) to a metallic ferromagnet (x>0.16) due to the\ninduced charge carriers (holes). Neutron scattering experiments were employed\nto investigate the effect of Sr doping on a tailor-made compound of composition\nLa(0.7)Sr(0.3)Mn(0.1)Ti(0.3)Ga(0.6)O(3). By the simultaneous doping with Sr2+\nand Ti4+ ions the compound remains in the insulating state, so that the\nmagnetic interactions for large Sr doping can be studied in the absence of\ncharge carriers. At TC=215 K there is a first-order reconstructive phase\ntransition from the trigonal R-3c structure to the orthorhombic Pnma structure\nvia an intermediate virtual configuration described by the common monoclinic\nsubgroup P21/c. The magnetic excitations associated with Mn3+ dimers give\nevidence for two different nearest-neighbor ferromagnetic exchange\ninteractions, in contrast to the undoped compound LaMnyA(1-y)O(3) where both\nferromagnetic and antiferromagnetic interactions are present. The doping\ninduced changes of the exchange coupling originates from different Mn-O-Mn bond\nangles determined by neutron diffraction. The large fourth-nearest-neighbor\ninteraction found for metallic manganites is absent in the insulating state. We\nargue that the Ruderman-Kittel-Kasuya-Yosida interaction reasonably accounts\nfor all the exchange couplings derived from the spin-wave dispersion in\nmetallic manganites."
    },
    {
        "anchor": "In-plane ordering and tunable magnetism in Cr-based MXenes: MXene, the two-dimensional derivatives of MAX compounds, due to their\nstructural and compositional flexibility, is an ideal family of compounds to\nstudy a number of structure-property relations. In this work, we have\ninvestigated the tunability of magnetic properties in Cr-based MXenes that have\nan in-plane ordering arising out of alloying Cr with another non-magnetic\ntransition metal atom. Using Density Functional Theory based calculations we\nhave explored the effects of composition and surface functionalisations on the\nelectronic and magnetic properties of these in-plane ordered MXenes known as\ni-MXenes. We found that the electronic and magnetic ground states are quite\nsensitive to the structure and composition. This provides enough tunability in\nthese compounds so that they can be used for practical applications. Our\ncalculated results of magnetic transition temperatures and magnetic anisotropy\nenergies are comparable to many a established two-dimensional magnets. These\nput together widen the prospect of these i-MXenes for multiple usage as\nmagnetic devices making them attractive for further investigation.",
        "positive": "Unconventional phase selection in high-driven systems: A complex\n  metastable structure prevails over simple stable phases: Phase selection in deeply undercooled liquids and devitrified glasses during\nheating involves complex interplay between the barriers to nucleation and the\nability for these nuclei to grow. During the devitrification of glassy alloys,\ncomplicated metastable structures often precipitate instead of simpler, more\nstable compounds. Here, we access this unconventional type of phase selections\nby investigating an Al-10%Sm system, where a complicated cubic structure first\nprecipitates with a large lattice parameter of 1.4 nm. We not only solve the\nstructure of this \"big cubic\" phase containing ~140 atoms but establish an\nexplicit interconnection between the structural orderings of the amorphous\nalloy and the cubic phase, which provides a low-barrier nucleation pathway at\nlow temperatures. The surprising rapid growth of the crystal is attributed to\nits high tolerance to point defects, which minimize the short-scale atomic\nrearrangements to form the crystal. Our study suggests a new scenario of\ndevitrification, where phase transformation proceeds initially without\npartitioning through a complex intermediate crystal phase."
    },
    {
        "anchor": "Ultra-sensitive label-free in-situ detection of dynamically driven\n  self-assembly of 2D nanoplatelets on SOI chip: Fluid dispersed two-dimensional (2D) composite materials with dynamically\ntunable functional properties have recently emerged as a novel highly promising\nclass of optoelectronic materials, opening up new routes not only for the\nemerging field of metamaterials but also to chip-scale multifunctional\nmetadevices. However, in-situ monitoring and detection of the dynamic ordering\nof 2D nanoparticles on chip and during the device operation is still a huge\nchallenge. Here we introduce a novel approach for on-chip, in-situ Raman\ncharacterisation of 2D-fluid composite materials incorporated into Si photonics\nchip. In this work the Raman signal for 2D nanoplatelets is selectively\nenhanced by Fabry-Perot resonator design of CMOS photonic-compatible\nmicrofluidic channels. This has then been extended to demonstrate the first\nin-situ Raman detection of the dynamics of individual 2D nanoplatelets, within\na microfluidic channel. Our work paves the way for the first practicable\nrealisation of 3D photonic microstructure shaping based on 2D-fluid composites\nand CMOS photonics platform.",
        "positive": "Semiconductor characterization by scanning ion beam induced charge\n  (IBIC) microscopy: The acronym IBIC (Ion Beam Induced Charge) was coined in early 1990's to\nindicate a scanning microscopy technique which uses MeV ion beams as probes to\nimage the basic electronic properties of semiconductor materials and devices.\nSince then, IBIC has become a widespread analytical technique to characterize\nmaterials for electronics or for radiation detection, as testified by more than\n200 papers published so far in peer-reviewed journals. Its success stems from\nthe valuable information IBIC can provide on charge transport phenomena\noccurring in finished devices, not easily obtainable by other analytical\ntechniques. However, IBIC analysis requires a robust theoretical background to\ncorrectly interpret experimental data. In order to illustrate the importance of\nusing a rigorous mathematical formalism, we present in this paper a benchmark\nIBIC experiment aimed to test the validity of the interpretative model based on\nthe Gunn's theorem and to provide an example of the analytical capability of\nIBIC to characterize semiconductor devices."
    },
    {
        "anchor": "Visibility study of graphene multilayer structures: The visibility of graphene sheets on different types of substrates has been\ninvestigated both theoretically and experimentally. Although single layer\ngraphene is observable on various types of dielectrics under an optical\nmicroscope, it is invisible when it is placed directly on most of the\nsemiconductor and metallic substrates. We show that coating of a resist layer\nwith optimum thickness is an effective way to enhance the contrast of graphene\non various types of substrates and makes single layer graphene visible on most\nsemiconductor and metallic substrates. Experiments have been performed to\nverify the results on quartz and NiFe-coated Si substrates. The results\nobtained will be useful for fabricating graphene-based devices on various types\nof substrates for electronics, spintronics and optoelectronics applications.",
        "positive": "Emergence of insulating ferrimagnetism and perpendicular magnetic\n  anisotropy in 3d-5d perovskite oxide composite films for insulator spintronic: Magnetic insulators with strong perpendicular magnetic anisotropy (PMA) play\na key role in exploring pure spin current phenomena and developing\nultralow-dissipation spintronic devices, thereby it is highly desirable to\ndevelop new material platforms. Here we report epitaxial growth of\nLa2/3Sr1/3MnO3 (LSMO)-SrIrO3 (SIO) composite oxide films (LSMIO) with different\ncrystalline orientations fabricated by sequential two-target ablation process\nusing pulsed laser deposition. The LSMIO films exhibit high crystalline quality\nwith homogeneous mixture of LSMO and SIO at atomic level. Ferrimagnetic and\ninsulating transport characteristics are observed, with the\ntemperature-dependent electric resistivity well fitted by Mott\nvariable-range-hopping model. Moreover, the LSMIO films show strong PMA.\nThrough further constructing all perovskite oxide heterostructures of the\nferrimagnetic insulator LSMIO and a strong spin-orbital coupled SIO layer,\npronounced spin Hall magnetoresistance (SMR) and spin Hall-like anomalous Hall\neffect (SH-AHE) were observed. These results illustrate the potential\napplication of the ferrimagnetic insulator LSMIO in developing all-oxide\nultralow-dissipation spintronic devices."
    },
    {
        "anchor": "Diffusion of hydrogen within idealised grains of bcc-Fe: A kinetic Monte\n  Carlo study: Structural defects in materials such as vacancies, grain boundaries, and\ndislocations may trap hydrogen and a local accumulation of hydrogen at these\ndefects can lead to the degradation of the materials properties. An important\naspect in obtaining insight into hydrogen induced embrittlement on the\natomistic level is to understand the diffusion of hydrogen in these materials.\nIn our study we employ kinetic Monte Carlo (kMC) simulations to investigate\nhydrogen diffusion in bcc iron within different microstructures. All input data\nto the kMC model, such as available sites, solution energies, and diffusion\nbarriers are obtained from first-principles calculations. We find that hydrogen\nmainly diffuses within the interface region with an overall diffusivity that is\nlower than in pure bcc-Fe bulk. The concentration dependence of the diffusion\ncoefficient is strongly non-linear and the diffusion coefficient may even\ndecrease with increasing hydrogen concentration. To describe the macroscopic\ndiffusion coefficient we derive an analytic expression as a function of\nhydrogen concentration and temperature which is in excellent agreement with our\nnumerical results for idealised microstructures.",
        "positive": "Hyperfine Interactions in Graphene and Related Carbon Nanostructures: Hyperfine interactions, magnetic interactions between the spins of electrons\nand nuclei, in graphene and related carbon nanostructures are studied. By using\na combination of accurate first principles calculations on graphene fragments\nand statistical analysis, I show that both isotropic and dipolar hyperfine\ninteractions can be accurately described in terms of the local electron spin\ndistribution and atomic structure. A complete set of parameters describing the\nhyperfine interactions of C-13 and other nuclear spins at substitution\nimpurities and edge terminations is determined."
    },
    {
        "anchor": "New Honeycomb Iridium (V) Oxides: NaIrO$_3$ and Sr$_3$CaIr$_2$O$_9$: We report the structures and physical properties of two new iridates,\nNaIrO$_3$ and Sr$_3$CaIr$_2$O$_9$, both of which contain continuous\ntwo-dimensional honeycomb connectivity. NaIrO3 is produced by room temperature\noxidative deintercalation of sodium from Na$_2$IrO$_3$, and contains\nedge-sharing IrO6 octahedra that form a planar honeycomb lattice.\nSr$_3$CaIr$_2$O$_9$, produced via conventional solid-state synthesis, hosts a\nbuckled honeycomb lattice with novel corner-sharing connectivity between IrO6\noctahedra. Both of these new compounds are comprised of Ir$^{5+}$ (5$d^4$) and\nexhibit negligible magnetic susceptibility. They are thus platforms to\ninvestigate the origin of the nonmagnetic behavior exhibited by Ir$^{5+}$\noxides, and provide the first examples of a $J$ = 0 state on a honeycomb\nlattice.",
        "positive": "The origin of the red luminescence in Mg-doped GaN: Optically-detected magnetic resonance (ODMR) and positron annihilation\nspectroscopy (PAS) experiments have been employed to study magnesium-doped GaN\nlayers grown by metal-organic vapor phase epitaxy. As the Mg doping level is\nchanged, the combined experiments reveal a strong correlation between the\nvacancy concentrations and the intensity of the red photoluminescence band at\n1.8 eV. The analysis provides strong evidence that the emission is due to\nrecombination in which electrons both from effective mass donors and from\ndeeper donors recombine with deep centers, the deep centers being\nvacancy-related defects."
    },
    {
        "anchor": "Simulated Dynamics and Endohedral Relesase of Ne from Ne@C60 Clusters: Molecular Dynamics (MD) computer simulations are utilized to better\nunderstand the escape of neon from small (N=5) endohedral Ne@C60 clusters.\nMultiple runs at various temperatures are used to increase the reliability of\nour statistics. The cluster holds together until somewhere between T = 1150K\nand T = 1200K, where it dissociates, showing no intermediate sign of melting or\nfullerene disintegration. When the temperature is increased to around T =\n4000K, the encapsulated neon atoms begin to leave the cluster, with the\nfullerene molecules still remaining intact. At temperatures near T = 4400K,\nthermal disintegration of the fullerenes pre-empts the cluster dissociation.\nThe neon atoms are then more quickly released and the fullerenes form a larger\nconnected structure, with bonding taking place in atom pairs from different\noriginal fullerene molecules. Escape constants and half lives are calculated\nfor the temperature range 4000K < T < 5000K. The agreements and disagreements\nof results of this work with experiments suggest that classical MD simulations\nare useful in describing fullerene systems at low temperatures and near\ndisintegration, but require more thought and modification before accurately\nmodeling windowing at temperatures below T = 3000K.",
        "positive": "An attempt to obtain Bi_{4}Ti_{3}O_{12}-PVC textured ceramics-polymer\n  composites: Bi_{4}Ti_{3}O_{12}-PVC composites were fabricated. Ceramics powders of\nbismuth titanate were prepared by the sol-gel method using bismuth nitrate\npentahydrate Bi(NO_{3})_{3} \\cdot 5H_{2}O and tetrabutyl titanate\nTi(CH_{3}(CH_{2})_{3}O)_{4} as precursors. The Bi_{4}Ti_{3}O_{12}-PVC\ncomposites were fabricated from ceramics powders and polymer powders by\nhot-pressing method."
    },
    {
        "anchor": "Thermal Hall effect in a van der Waals ferromagnet CrI3: CrI3 is a prototypical van der Waals ferromagnet with a magnetic honeycomb\nlattice. Previous inelastic neutron scattering studies have suggested\ntopological nature of its magnetic excitations with a magnon gap at the Dirac\npoints, which are anticipated to give rise to magnon thermal Hall effect. Here\nwe report thermal transport properties of CrI3 and show that the long-sought\nthermal Hall signal anticipated for topological magnons is fairly small. In\ncontrast, we find that CrI3 exhibits an appreciable anomalous thermal Hall\nsignal at lower temperature which may arise from magnon-phonon hybridization or\nmagnon-phonon scattering. These findings are anticipated to stimulate further\nneutron scattering studies on CrI3 single crystal, which can shed light not\nonly on the intrinsic nature of magnetic excitations but also on the\nmagnon-phonon interaction.",
        "positive": "Ab initio study of the optical phonons in 1D antiferromagnet Ca2CuO3: In the spin 1/2 antiferromagnetic Ca2CuO3 the optical excitation along 1D a\nCu-O chain showed the enrichment of forbidden peaks that could not be explained\nby the group theory. We present the cluster-model ab initio study of these\noptical phonons based on the Hartree-Fock SCF calculation with the 3-21G basic\nset. The obtained results showed very good agreement with the observed data.\nThe Cu-O resonances generally showed the lower shifts in Ca2CuO3 than in pure\nCuO and were primarily composed of the vibrations of the oxygen in static host\nlattice whereas the Cu movements happened only in the collective lattice\nvibrations. Almost complete classification of the forbidden phonons is\npresented."
    },
    {
        "anchor": "Tuning Structural, Transport and Magnetic Properties of Epitaxial SrRuO3\n  through Ba-Substitution: The perovskite ruthenates (ARuO3, A = Ca, Ba, or Sr) exhibit unique\nproperties owing to a subtle interplay of crystal structure and electronic-spin\ndegrees of freedom. Here, we demonstrate an intriguing continuous tuning of\ncrystal symmetry from orthorhombic to tetragonal (no octahedral rotations)\nphases in epitaxial SrRuO3 achieved via Ba-substitution (Sr1-xBaxRuO3 with 0 <\nx < 0.7). An initial Ba-substitution to SrRuO3 not only changes the\nferromagnetic properties, but also tunes the perpendicular magnetic anisotropy\nvia flattening the Ru-O-Ru bond angle (to 180{\\deg}), resulting in the maximum\nCurie temperature and an extinction of RuO6 rotational distortions at x = 0.20.\nFor x > 0.2, the suppression of RuO6 octahedral rotational distortion\ndominantly enhances the ferromagnetism in the system, though competing with the\nimpact of the RuO6 tetragonal distortion. Further increasing x > 0.2 gradually\nenhances the tetragonal-type distortion, resulting in the tuning of Ru-4d\norbital occupancy and suppression of ferromagnetism. Our results demonstrate\nthat isovalent substitution of the A-site cations significantly and\ncontrollably impacts both electronic and magnetic properties of perovskite\noxides.",
        "positive": "Is there a critical acceleration for the onset of convection?: Suppose granular material is shaken vertically with z(t)=A_0 cos(\\omega_0 t).\nCan we expect to find convection if A_0\\omega_0^2 < g? By means of theoretical\nanalysis and computer simulation we find that there is no critical\n\\Gamma=|A_0|\\omega_0^2/g for the onset of convection. Instead we propose a\nmodified criterion which coincides with \\Gamma=1 for small frequency \\omega_0."
    },
    {
        "anchor": "Efficacious calculation of Raman spectra in high pressure hydrogen: We present and evaluate an efficient method for simulating Raman spectra from\nmolecular dynamics (MD) calculations {\\it without} defining normal modes. We\napply the method to high pressure hydrogen in the high-temperature \"Phase IV\":\na plastic crystal in which the conventional picture of fixed phonon eigenmodes\nbreaks down.\n  Projecting trajectories onto in-phase molecular stretches is shown to be many\norders of magnitude faster than polarisability calculations, allowing\nstatistical averaging at high-temperature.\n  The simulations are extended into metastable regimes and identify several\nregimes associated with symmetry-breaking on different timescales, which are\nshown to exhibit features in the Raman spectra at the current experimental\nlimit of resolvability. In this paper we have concentrated on the methodology,\na fuller description of the structure of Phase IV hydrogen is given in a\nprevious paper",
        "positive": "Nonlinear photoluminescence imaging of isotropic and liquid crystalline\n  dispersions of graphene oxide: We report a visible-range nonlinear photoluminescence (PL) from graphene\noxide (GO) flakes excited by near-infrared femtosecond laser light. PL\nintensity has nonlinear dependence on the laser power, implying a multiphoton\nexcitation process, and also strongly depends on a linear polarization\norientation of excitation light, being at maximum when it is parallel to\nflakes. We show that PL can be used for a fully three-dimensional label-free\nimaging of isotropic, nematic, and lamellar liquid crystalline dispersions of\nGO flakes in water. This nonlinear PL is of interest for applications in direct\nlabel-free imaging of composite materials and study of orientational ordering\nin mesomorphic phases formed by these flakes, as well as in biomedical and\nsensing applications utilizing GO."
    },
    {
        "anchor": "Correlation between site preference of ternary Mn addition in LaAg and\n  superconductivity: The results of an extensive investigation of structure, surface morphology,\ncomposition and the superconducting-normal phase diagram of a new\nunconventional superconductor LaAg1-cMnc with nominal composition c = 0.0,\n0.025, 0.05, 0.1, 0.2 and 0.3, reveal the following. The alloys with c = 0,\n0.025 and 0.05 are essentially single phase alloys with the actual Mn\nconcentration, x, same as the nominal one, i.e., c = x, whereas in the alloys\nwith c = 0.1, 0.2 and 0.3, the actual Mn concentration of the majority phase\n(crystalline grains) is x = 0.050(1), 0.080(1) and 0.100(1), respectively. The\nternary Mn addition does not alter the CsCl structure of the parent compound\nLaAg. Neither a structural phase transition occurs nor a long-range\nantiferromagnetic order exists at any temperature within the range 1.8K < = T <\n= 50K in any of the Mn containing alloys. Mn has exclusive La (Ag) site\npreference in the alloy (alloys) with x = c = 0.025 (x < = 0.05 or c < = 0.1)\nwhereas in the alloy with x = c = 0.05, Mn has essentially no site preference\nin that all the Mn atoms either occupy the La sites or the Ag sites. In the\nalloys (alloy) with x < = 0.05 (x = c = 0.025), substitution of Ag (La) by Mn\nat the Ag (La) sub-lattice sites in LaAg host gives rise to unconventional\nsuperconductivity (destroys the conventional phonon-mediated superconductivity\nprevalent in the parent LaAg compound).",
        "positive": "Exploring interfacial exchange coupling and sublattice effect in heavy\n  metal/ferrimagnetic insulator heterostructures using Hall measurements, x-ray\n  magnetic circular dichroism, and neutron reflectometry: We use temperature-dependent Hall measurements to identify contributions of\nspin Hall, magnetic proximity, and sublattice effects to the anomalous Hall\nsignal in heavy metal/ferrimagnetic insulator heterostructures with\nperpendicular magnetic anisotropy. This approach enables detection of both the\nmagnetic proximity effect onset temperature and the magnetization compensation\ntemperature and provides essential information regarding the interfacial\nexchange coupling. Onset of a magnetic proximity effect yields a local extremum\nin the temperature-dependent anomalous Hall signal, which occurs at higher\ntemperature as magnetic insulator thickness increases. This magnetic proximity\neffect onset occurs at much higher temperature in Pt than W. The magnetization\ncompensation point is identified by a sharp anomalous Hall sign change and\ndivergent coercive field. We directly probe the magnetic proximity effect using\nx-ray magnetic circular dichroism and polarized neutron reflectometry, which\nreveal an antiferromagnetic coupling between W and the magnetic insulator.\nFinally, we summarize the exchange-coupling configurations and the anomalous\nHall-effect sign of the magnetized heavy metal in various heavy metal/magnetic\ninsulator heterostructures."
    },
    {
        "anchor": "Neural Cellular Automata for Solidification Microstructure Modelling: We propose Neural Cellular Automata (NCA) to simulate the microstructure\ndevelopment during the solidification process in metals. Based on convolutional\nneural networks, NCA can learn essential solidification features, such as\npreferred growth direction and competitive grain growth, and are up to six\norders of magnitude faster than the conventional Cellular Automata (CA).\nNotably, NCA delivers reliable predictions also outside their training range,\nwhich indicates that they learn the physics of the solidification process.\nWhile in this study we employ data produced by CA for training, NCA can be\ntrained based on any microstructural simulation data, e.g. from phase-field\nmodels.",
        "positive": "Direct Observation of Room-Temperature Dislocation Plasticity in Diamond: It is well known that diamond does not deform plastically at room temperature\nand usually fails in catastrophic brittle fracture. Here we demonstrate\nroom-temperature dislocation plasticity in sub-micrometer sized diamond pillars\nby in-situ mechanical testing in the transmission electron microscope. We\ndocument in unprecedented details of spatio-temporal features of the\ndislocations introduced by the confinement-free compression, including\ndislocation generation and propagation. Atom-resolved observations with\ntomographic reconstructions show unequivocally that mixed-type dislocations\nwith Burgers vectors of 1/2<110> are activated in the non-close-packed {001}\nplanes of diamond under uniaxial compression of <111> and <110> directions,\nrespectively, while being activated in the {111} planes under the <100>\ndirectional loading, indicating orientation-dependent dislocation plasticity.\nThese results provide new insights into the mechanical behavior of diamond and\nstimulate reconsideration of the basic deformation mechanism in diamond as well\nas in other brittle covalent crystals at low temperatures."
    },
    {
        "anchor": "Aggregation of P-terphenyl along with PMMA/SA at the Langmuir and\n  Langmuir-Blodgett Films: Molecular aggregation and monolayer characteristics of non-amphiphilic\np-terphenyl (TP) mixed with either polymethyl methacrylate (PMMA) or stearic\nacid (SA) at the air-water interface were investigated. The miscibility of the\ntwo components was evaluated by measuring and analyzing surface pressure versus\narea per molecule (pi-A) isotherm. Both attractive and repulsive interactions\nbetween the sample (TP) and the matrix (PMMA or SA) were observed depending on\nthe composition and microenvironment. TP and PMMA/SA were not completely\nmiscible in the mixed monolayer. Aggregation and phase separation between\nsample TP and matrix molecule was revealed by UV-Vis absorption spectroscopic\nstudies and confirmed by scanning electron micrograpgh of LB films.",
        "positive": "Solid-liquid coexistence of the noble elements. I. Theory illustrated by\n  the case of argon: The noble elements constitute the simplest group of atoms. At low\ntemperatures or high pressures they freeze into the face-centered cubic (fcc)\ncrystal structure (except helium). We perform molecular dynamics using the\nrecently proposed simplified ab initio atomic (SAAP) potential [Deiters and\nSadus, J. Chem. Phys. 150, 134504 (2019)] . This potential is parameterized\nusing data from accurate ab initio quantum mechanical calculations by the\ncoupled-cluster approach on the CCSD(T) level. We compute the fcc freezing\nlines for Argon and find a great agreement with the experimental values. At low\npressures, this agreement is further enhanced by using many-body corrections.\nHidden scale invariance of the potential energy function is validated by\ncomputing lines of constant excess entropy (configurational adiabats) and shows\nthat mean square displacement and the static structure factor are invariant.\nThese lines (isomorphs) can be generated from simulations at a single\nstate-point by having knowledge of the pair potential. The isomorph theory for\nthe solid-liquid transition is used to accurately predict the shape of the\nfreezing line in the pressure-temperature plane, the shape in the\ndensity-temperature plane, the entropy of melting and the Lindemann parameters\nalong the melting line. We finally predict that the body-centered cubic (bcc)\ncrystal is stable at high pressures."
    },
    {
        "anchor": "Nonequilibrium free-energy calculation of phase-boundaries using LAMMPS: We present a guide to compute the phase-boundaries of classical systems using\na dynamic Clausius-Clapeyron integration (dCCI) method within the LAMMPS\n(Large-scale Atomic/Molecular Massively Parallel Simulator) code. The advantage\nof the dCCI method is because it provides coexistence curves spanning a wide\nrange of thermodynamic states using relatively short single non-equilibrium\nsimulations. We describe the state-of-the-art of non-equilibrium free-energy\nmethods that allow us to compute the Gibbs free-energy in a wide interval of\npressure and/or temperature. We present the dCCI method in details, discuss its\nimplementation in the LAMMPS package and make available source code, scripts,\nas well as auxiliary files. As an illustrative example, we determine the phase\ndiagram of silicon in a range of pressures covering from 0 to 15 GPa and\ntemperatures as low as 400 K up to the liquid phase, in order to obtain the\nphase boundaries and triple point between diamond, liquid and beta-Sn phases.",
        "positive": "Wave functions for quantum Monte Carlo calculations in solids: Orbitals\n  from density functional theory with hybrid exchange-correlation functionals: We investigate how the fixed-node diffusion Monte Carlo energy of solids\ndepends on single-particle orbitals used in Slater--Jastrow wave functions. We\ndemonstrate that the dependence can be significant, in particular in the case\nof 3d transition-metal compounds, which we adopt as examples. We illustrate how\nexchange-correlation functionals with variable exact-exchange component can be\nexploited to reduce the fixed-node errors. On the basis of these results we\nargue that the fixed-node quantum Monte Carlo provides a variational approach\nfor optimization of effective hamiltonians with parameters."
    },
    {
        "anchor": "Room temperature surface piezoelectricity in SrTiO3 ceramics via\n  piezoresponse force microscopy: SrTiO3 ceramics are investigated by piezoresponse force microscopy.\nPiezoelectric contrast is observed on polished surfaces in both vertical and\nlateral regimes and depends on the grain orientation varying in both sign\n(polarization direction) and amplitude. The observed contrast is attested to\nthe surface piezoelectricity due to flexoelectric effect (strain\ngradient-induced polarization) caused by the surface relaxation. The estimated\nflexoelectric coefficient is approximately one order of magnitude smaller as\ncompared to those recently measured in SrTiO3 single crystals. The observed\nenhancement of piezoresponse signal at the grain boundaries is explained by the\ndipole moments associated with inhomogeneous distribution of oxygen vacancies.",
        "positive": "Interfacial Dzyaloshinskii-Moriya interaction, surface anisotropy\n  energy,and spin pumping at spin orbit coupled Ir/Co interface: The interfacial Dzyaloshinskii-Moriya interaction (iDMI), surface anisotropy\nenergy, and spin pumping at the Ir/Co interface are experimentally investigated\nby performing Brillouin light scattering. Contrary to previous reports, we\nsuggest that the sign of the iDMI at the Ir/Co interface is the same as in the\ncase of the Pt/Co interface. We also find that the magnitude of the iDMI energy\ndensity is relatively smaller than in the case of the Pt/Co interface, despite\nthe large strong spin-orbit coupling (SOC) of Ir. The saturation magnetization\nand the perpendicular magnetic anisotropy (PMA) energy are significantly\nimproved due to a strong SOC. Our findings suggest that an SOC in an Ir/Co\nsystem behaves in different ways for iDMI and PMA. Finally, we determine the\nspin pumping effect at the Ir/Co interface, and it increases the Gilbert\ndamping constant from 0.012 to 0.024 for 1.5 nmthick Co."
    },
    {
        "anchor": "Josephson Effect and Charge Distribution in Thin Bi$_2$Te$_3$\n  Topological Insulators: Thin layers of topological insulator materials are quasi-two-dimensional\nsystems featuring a complex interplay between quantum confinement and\ntopological band structure. To understand the role of the spatial distribution\nof carriers in electrical transport, we study the Josephson effect,\nmagnetotransport, and weak anti-localization in bottom-gated thin Bi$_2$Te$_3$\ntopological insulator films.We compare the experimental carrier densities to a\nmodel based on the solutions of the self-consistent Schr\\\"odinger-Poisson\nequations and find excellent agreement. The modeling allows for a quantitative\ninterpretation of the weak antilocalization correction to the conduction and of\nthe critical current of Josephson junctions with weak links made from such\nfilms without any ad hoc assumptions.",
        "positive": "Time-resolved impulse response of the magnetoplasmon resonance in a\n  two-dimensional electron gas: We have used optically excited ultrashort electrical pulses to measure the\nmagnetoplasmon resonance of a two-dimensional electron gas formed in an\nAlGaAs/GaAs heterostructure at frequencies up to 200 gigahertz. This is\naccomplished by incorporating the sample into a guided wave probe operating in\na pumped (^{3}He) system. We are able to detect the resonance by launching a\nstimulus pulse in the guide, and monitoring the system response in a time\nresolved pump-probe arrangement. Data obtained from measurements yield resonant\nfrequencies that agree with the magnetoplasmon dispersion relation."
    },
    {
        "anchor": "Computational diffraction reveals long-range strains, disorder and\n  crystalline domains in atomic scale simulations: Atomic scale simulations are a key element of modern science in that they\nallow to understand, and even predict, complex physical or chemical phenomena\non the basis of the fundamental laws of nature. Among the different existing\natomic scale simulation approaches, molecular dynamics (MD) has imposed itself\nas the method of choice to model the behavior of the structure of materials\nunder the action of external stimuli, say temperature, strain or stress,\nirradiation, etc. Despite the widespread use of MD in condensed matter science,\nsome basic material characteristics remain difficult to determine. This is for\ninstance the case of the long-range strain tensor in heavily disordered\nmaterials, or the quantification of rotated crystalline domains lacking clearly\ndefined boundaries. In this work, we introduce computational diffraction as a\nfast and reliable structural characterization tool of atomic scale simulation\ncells. As compared to usual direct-space methods, computational diffraction\noperates in the reciprocal-space and is therefore highly sensitive to\nlong-range spatial correlations. With the example of defective UO2, it is\ndemonstrated that the homogeneous strain tensor, the heterogeneous strain\ntensor, the disorder, as well as rotated crystallites are straightforwardly and\nunambiguously determined. Computational diffraction can be applied to any type\nof atomic scale simulation and can be performed in real time, in parallel with\nother analysis tools. In experimental workflows, diffraction and microscopy are\nalmost systematically used together in order to benefit from their\ncomplementarity. Computational diffraction, used together with computational\nmicroscopy, can potentially play a major role in the future of atomic scale\nsimulations.",
        "positive": "Enhanced spin reorientation temperature and origin of magnetocapacitance\n  in HoFeO3: We report on the increase in the spin reorientation temperature in\nHoFe0.5Cr0.5O3 compound by isovalent substitution Cr3+ at the Fe-site and the\nmagnetocapacitance in the HoFeO3 compound. Spin reorientation transition is\nevident around 50 K and 150 K for the x = 0 and x = 0.5 compounds respectively.\nThe increase in the spin reorientation transition temperature in case of x =\n0.5 compound can be attributed to the domination of the Ho3+ to Fe3+\ninteraction over the Fe3+ to Fe3+ interaction. Decrease in Neel temperature\nfrom 643 K (x = 0) to 273 K (x = 0.5) can be ascribed to the decrease in the\ninteraction between antiferromagnetically aligned Fe3+ moments as a result of\nthe dilution of the Fe3+ moments with the Cr3+ addition. From the magnetization\nM vs magnetic field H variation it is evident that the coercivity, HC decreases\nfor x = 0.5 compound, hinting the magnetic softening of the HoFeO3 compound.\nObserved magnetocapacitance could be due to lossy dielectric mechanism in the\npresent compound. Indeed, present results would be helpful in understanding the\nphysics behind rare- earth orthoferrites."
    },
    {
        "anchor": "Revealing the configurations and host-guest interactions of small\n  aromatics confined in porous frameworks by electron microscopy: Directly imaging the configurations of small molecules at the ambient\ntemperatures will greatly promote the study of their chemical and physical\nproperties, including the host-guest interactions of organics in porous\nmaterials during the adsorption, catalysis and energy storage. However, due to\nthe current challenges on the small-molecule imaging by the (scanning)\ntransmission electron microscopy ((S)TEM), we still have a lack of the\nmolecular-level understandings on the host-guest interactions and other\nmolecular behaviors. Here, we achieved the STEM imaging of various small\naromatics confined in the MFI-type zeolite frameworks by using the integrated\ndifferential phase contrast (iDPC) technique. Due to the strong confinement\neffect in MFI channels, the 1D solid-like aromatic columns showed the coherent\nconfigurations, which were clearly resolved by enhancing the host-guest\ninteractions. Then, we also evaluated the strength of host-guest interactions\ndirectly by the image analysis and revealed the desorption behaviors of\nconfined aromatics during the in-situ heating process. These results not only\nhelped us to reveal the configurations and host-guest interactions of small\naromatics during the adsorption/desorption in porous materials, but also\nexpanded the applications of STEM to further study other molecular behaviors in\nthe real space.",
        "positive": "Elastic and electronic tuning of magnetoresistance in MoTe$_2$: Quasi-two dimensional transition metal dichalcogenides (TMD) exhibit dramatic\nproperties that may transform electronic and photonic devices. We report on how\nthe anomalously large magnetoresistance (MR) observed under high magnetic field\nin MoTe$_2$, a type II Weyl semimetal, can be reversibly controlled under\ntensile strain. The MR is enhanced by as much as ~ 30 % at low temperatures and\nhigh magnetic fields, when uniaxial strain is applied along the\n$a$-crystallographic direction and reduced by about the same amount when strain\nis applied along the $b$-direction. We show that the large in-plane electric\nanisotropy is coupled with the structural transition from the 1T' monoclinic to\nthe Td orthorhombic Weyl phase. A shift of the Td - 1T' phase boundary is\nachieved by minimal tensile strain. The sensitivity of the MR to tensile strain\nsuggests the possibility of a nontrivial spin-orbital texture of the electron\nand hole pockets in the vicinity of Weyl points. Our ab initio calculations\nindeed show a significant orbital mixing on the Fermi surface, which is\nmodified by the tensile strains."
    },
    {
        "anchor": "Invariant form of spin-transfer switching condition: We derive an invariant form of the current-induced switching condition in\nspin-transfer devices and show that for energy minima and maxima the \"switching\nability\" of the current is determined by the spin torque divergence. In\ncontrast, energy saddle points are normally stabilized by current-induced\nmerging with other equilibria. Our approach provides new predictions for\nseveral experimental setups and shows the limitations of some frequently used\napproximations.",
        "positive": "Decoherence in Josephson Qubits from Dielectric Loss: Dielectric loss from two-level states is shown to be a dominant decoherence\nsource in superconducting quantum bits. Depending on the qubit design,\ndielectric loss from insulating materials or the tunnel junction can lead to\nshort coherence times. We show that a variety of microwave and qubit\nmeasurements are well modeled by loss from resonant absorption of two-level\ndefects. Our results demonstrate that this loss can be significantly reduced by\nusing better dielectrics and fabricating junctions of small area $\\lesssim 10\n\\mu \\textrm{m}^2$. With a redesigned phase qubit employing low-loss\ndielectrics, the energy relaxation rate has been improved by a factor of 20,\nopening up the possibility of multi-qubit gates and algorithms."
    },
    {
        "anchor": "High Curie Temperature Ferromagnetic Semiconductor: Bimetal Transition\n  Iodide V$_2$Cr$_2$I$_9$: Bimetal transition iodides in two-dimensional scale provide an interesting\nidea to combine a set of single-transition-metal ferromagnetic semiconductors\ntogether. Motivated by structural engineering on bilayer CrI$_3$ to tune its\nmagnetism and works that realize ideal properties by stacking van der Waals\ntransitional metal dichalcogenides in a certain order. Here we stack monolayer\nVI$_3$ onto monolayer CrI$_3$ with a middle-layer I atoms discarded to\nconstruct monolayer V$_2$Cr$_2$I$_9$. Based on this crystal model, the stable\nand metastable phases are determined among 7 possible phases by\nfirst-principles calculations. It is illustrated that both the two phases have\nCurie temperature $\\sim$ 6 (4) times higher than monolayer CrI$_3$ and VI$_3$.\nThe reason can be partly attributed to their large magnetic anisotropy energy\n(the maximum value reaches 412.9 $\\mu$eV/atom). More importantly, the Curie\ntemperature shows an electric field and strain dependent character and can even\nsurpass room temperature under a moderate strain range. At last, we believe\nthat the bimetal transition iodide V$_2$Cr$_2$I$_9$ monolayer would support\npotential opportunities for spintronic devices.",
        "positive": "Assessment of full field crystal plasticity finite element method for\n  forming limit diagram prediction: This study is inspired by the recent development of \"virtual material testing\nlaboratory\" in which the main equipment is a full field crystal plasticity\nmodeling tool. Ample examples have demonstrated its applications to sheet\nforming operations. In those applications, the mechanical anisotropy originated\nfrom the crystallographic texture can be adequately described, such as r-values\nand earing. Formability is another important property in sheet metal forming,\nwhich has yet not been equipped in these virtual laboratories. Though\ntheoretical models for formability can be dated back to 1885 due to\nConsid\\`{e}re, all popular models at the moment suffer from their respective\nlimitations. In this study, we explore the feasibility of applying full field\ncrystal plasticity model for calculating forming limit diagram, avoiding using\nadditional assumptions or models for determining the forming limits."
    },
    {
        "anchor": "Dynamic Phase Transitions for Ferromagnetic Systems: This article presents a phenomenological dynamic phase transition theory for\nferromagnetism, leading to a precise description of the dynamic transitions,\nand to a physical predication on the spontaneous magnetization. The analysis\nalso suggests asymmetry of fluctuations in both the ferromagnetism and the PVT\nsystems.",
        "positive": "Oxygen vacancies: The origin of n-type conductivity in ZnO: Oxygen vacancy (VO) is a common native point defects that plays crucial roles\nin determining the physical and chemical properties of metal oxides such as\nZnO. However, fundamental understanding of VO is still very sparse.\nSpecifically, whether VO is mainly responsible for the n-type conductivity in\nZnO has been still unsettled in the past fifty years. Here we report on a study\nof oxygen self-diffusion by conceiving and growing oxygen-isotope ZnO\nheterostructures with delicately-controlled chemical potential and Fermi level.\nThe diffusion process is found to be predominantly mediated by VO. We further\ndemonstrate that, in contrast to the general belief of their neutral attribute,\nthe oxygen vacancies in ZnO are actually +2 charged and thus responsible for\nthe unintentional n-type conductivity as well as the non-stoichiometry of ZnO.\nThe methodology can be extended to study oxygen-related point defects and their\nenergetics in other technologically important oxide materials."
    },
    {
        "anchor": "Pyroelectric origin of the carrier density modulation at\n  graphene-ferroelectric interface: Using continuous approximation we study the static and high-frequency heat\ndissipation in multi-layer graphene on a ferroelectric. We demonstrate that the\nJoule heating effect, caused by a high-frequency ac electric current in\ngraphene, creates a pronounced temperature gradient in a ferroelectric\nsubstrate. The pyroelectric effect transforms the gradient into the spontaneous\npolarization gradient.. Therefore, the high-frequency depolarizing electric\nfield occurs and penetrates in the multi-layer graphene. Free charges in\ngraphene immediately screen the electric field and thus their density\noscillates at high-frequency. Performed calculations had proved that the\npyroelectric effect can modify essentially the free carrier density at the\ngraphene-ferroelectric interface and consequently the conductivity of\nmulti-layer graphene channel. So, pyroelectric mechanism can be critical for\nunderstanding of the complex physical thermal and electrical processes taking\nplace across and along graphene-ferroelectric interfaces at terahertz\nfrequencies.",
        "positive": "Scaling Confirmation of the Thermodynamic Dislocation Theory: We show that the thermodynamic dislocation theory (TDT) predicts a scaling\nrelation between stresses, strain rates, and temperatures for steady-state\ndeformations of crystalline solids, and that this relation is accurately obeyed\nby a wide range of experimental data for both aluminum and copper. Unlike\nconventional phenomenological dislocation theories, the TDT is based on the\nsecond law of thermodynamics. Its success implies that descriptions of solid\ndeformation that are not based on the statistical mechanics of nonequilibrium\nprocesses cannot be relied upon to be predictive. Thus there is an urgent need\n-- and a new opportunity -- to revitalize this central part of materials\nphysics."
    },
    {
        "anchor": "Towards New Half-Metallic Systems: Zinc-Blende Compounds of Transition\n  Elements with N, P, As, Sb, S, Se, and Te: We report systematic first-principles calculations for ordered zinc-blende\ncompounds of the transition metal elements V, Cr, Mn with the sp elements N, P,\nAs, Sb, S, Se, Te, motivated by recent fabrication of zinc-blende CrAs, CrSb,\nand MnAs. They show ferromagnetic half-metallic behavior for a wide range of\nlattice constants. We discuss the origin and trends of half-metallicity,\npresent the calculated equilibrium lattice constants, and examine the\nhalf-metallic behavior of their transition element terminated (001) surfaces.",
        "positive": "High quality epitaxial thin films and exchange bias of antiferromagnetic\n  Dirac semimetal FeSn: FeSn is a topological semimetal (TSM) and kagome antiferromagnet (AFM)\ncomposed of alternating Fe3Sn kagome planes and honeycomb Sn planes. This\nunique structure gives rise to exotic features in the band structures such as\nthe coexistence of Dirac cones and flatbands near the Fermi level, fully\nspin-polarized 2D surface Dirac fermions, and the ability to open a large gap\nin the Dirac cone by reorienting the N\\'eel vector. In this work, we report the\nsynthesis of high quality epitaxial (0001) FeSn films by magnetron sputtering.\nUsing FeSn/Py heterostructures, we show a large exchange bias effect that\nreaches an exchange field of 220 Oe at 5 K, providing unambiguous evidence of\nantiferromagnetism and strong interlayer exchange coupling in our films. Field\ncycling studies show steep initial training effects, highlighting the complex\nmagnetic interactions and anisotropy. Importantly, our work provides a simple,\nalternative means to fabricate FeSn films and heterostructures, making it\neasier to explore the topological physics of AFM TSMs and develop FeSn-based\nspintronics."
    },
    {
        "anchor": "Homogeneous Nucleation and Forest Hardening Result in Thermal Hardening\n  Phenomenon in Shock Loaded BCC Metals: Interpretation of thermal hardening phenomenon at high strain rate has\nrecently become a critical problem in shock wave physics. In this letter, this\nproblem is addressed from a viewpoint of dislocation generation, and a novel\nconclusion is gained that forest hardening induced by homogeneous nucleation\n(HN) results in thermal hardening behavior in a BCC metal significantly, apart\nfrom phonon drag mechanism. Through numerical simulations with a dislocation\nbased crystal plasticity model, we have reproduced the experimental results\nquantitatively and predicted a thermal hardening behavior in other BCC metals,\ni.e., Mo, at higher temperature.",
        "positive": "Intrinsic Origin of Negative Fixed Charge in Wet Oxidation for Silicon\n  Carbide: We demonstrate on the basis of first-principles calculations that the\nformation of carbonate-like moiety in SiO$_2$ could be the intrinsic origin of\nnegative fixed charge in SiC thermal oxidation. We find that two possible\norigins for the negative fixed charges are O-lone-pair state and a negatively\ncharged CO$_3$ ion in SiO$_2$. Such CO$_3$ ion is able to be formed as a result\nof the existence of residual C atoms in SiO$_2$, which are expected to be\nemitted from the interface between SiC and SiO$_2$, and the incorporation of H\natoms during wet oxidation."
    },
    {
        "anchor": "Direct observation of the layer-number-dependent electronic structure in\n  few-layer WTe2: When a crystal becomes thinner and thinner to the atomic level, peculiar\nphenomena discretely depending on its layer-numbers (n) start to appear. The\nsymmetry and wave functions strongly reflect the layer-numbers and stacking\norder, which brings us a potential of realizing new properties and functions\nthat are unexpected in either bulk or simple monolayer. Multilayer WTe2 is one\nsuch example exhibiting unique ferroelectricity and non-linear transport\nproperties related to the antiphase stacking and Berry-curvature dipole. Here\nwe investigate the electronic band dispersions of multilayer WTe2 (2-5 layers),\nby performing laser-based micro-focused angle-resolved photoelectron\nspectroscopy on exfoliated-flakes that are strictly sorted by n and\nencapsulated by graphene. We clearly observed the insulator-semimetal\ntransition occurring between 2- and 3-layers, as well as the 30-70 meV\nspin-splitting of valence bands manifesting in even n as a signature of\nstronger structural asymmetry. Our result fully demonstrates the possibility of\nthe large energy-scale band and spin manipulation through the finite n stacking\nprocedure.",
        "positive": "Kinetically-controlled epitaxial growth of Fe$_3$GeTe$_2$ van der Waals\n  ferromagnetic films: We demonstrate that kinetics play an important role in the epitaxial growth\nof Fe$_3$GeTe$_2$ (FGT) van der Waals (vdW) ferromagnetic films by molecular\nbeam epitaxy. By varying the deposition rate, we control the formation or\nsuppression of an initial tellurium-deficient non-van der Waals phase\n(Fe$_3$Ge$_2$) prior to realizing epitaxial growth of the vdW FGT phase. Using\ncross-sectional scanning transmission electron microscopy and scanning\ntunneling microscopy, we optimize the FGT films to have atomically smooth\nsurfaces and abrupt interfaces with the Ge(111) substrate. The magnetic\nproperties of our high quality material are confirmed through magneto-optic,\nmagnetotransport, and spin-polarized STM studies. Importantly, this\ndemonstrates how the interplay of energetics and kinetics can help tune the\nre-evaporation rate of chalcogen atoms and interdiffusion from the underlayer,\nwhich paves the way for future studies of van der Waals epitaxy."
    },
    {
        "anchor": "Photoemission Study of the Electronic Structure of Valence Band\n  Convergent SnSe: IV-VI semiconductor SnSe has been known as the material with record high\nthermoelectric performance.The multiple close-to-degenerate valence bands in\nthe electronic band structure has been one of the key factors contributing to\nthe high power factor and thus figure of merit in the SnSe single crystal. To\ndate, there have been primarily theoretical calculations of this particular\nelectronic band structure. In this paper, however, using angle-resolved\nphotoemission spectroscopy, we perform a systematic investigation of the\nelectronic structure of SnSe. We directly observe three predicted hole bands\nwith small energy differences between their band tops and relatively small\nin-plane effective masses, in good agreement with the ab initio calculations\nand critical for the enhancement of the Seebeck coefficient while keeping high\nelectrical conductivity. Our results reveal the complete band structure of SnSe\nand help to provide a deeper understanding of the electronic origin of the\nexcellent thermoelectric performances in SnSe.",
        "positive": "Thermal conductance of thin film YIG determined using Bayesian\n  statistics: Thin film YIG (Y$_3$Fe$_5$O$_{12}$) is a prototypical material for\nexperiments on thermally generated pure spin currents and the spin Seebeck\neffect. The 3-omega method is an established technique to measure the\ncross-plane thermal conductance of thin films, but can not be used in YIG/GGG\n(Ga$_3$Gd$_5$O$_{12}$) systems in its standard form. We use two-dimensional\nmodeling of heat transport and introduce a technique based on Bayesian\nstatistics to evaluate measurement data taken from the 3-omega method. Our\nanalysis method allows us to study materials systems that have not been\naccessible with the conventionally used 3-omega analysis. Temperature dependent\nthermal conductance data of thin film YIG are of major importance for\nexperiments in the field of spin-caloritronics. Here we show data between room\ntemperature and 10 K for films covering a wide thickness range as well as the\nmagnetic field effect on the thermal conductance between 10 K and 50 K."
    },
    {
        "anchor": "Spin-polarized bandgap of graphene induced by alternative chemisorption\n  with MgO (111) substrate: Using First-principle calculations, substrate effect of O-terminated (rt3 x\nrt3) MgO (111) on graphene was investigated for spintronics application.\nSurprisingly, the graphene can be turned into a spin-polarized semiconductor,\nwhich implies that the totally spin-polarized current can be generated and its\non/off switching can be also controlled. The origin of the spin-polarized band\nstructure is spin-ordering due to alternative sp2-sp3 covalent bondings induced\nby the MgO (111) substrate. The results indicate that the tailored pattern of\nthe chemisorption can be highly efficient or introducing totally spin-polarized\ncurrent to the graphene.",
        "positive": "Magnetic and magnetotransport properties of ThCr2Si2-type Ce2O2Bi\n  composed of conducting Bi2- square net and magnetic Ce-O layer: ThCr2Si2-type Ce2O2Bi epitaxial thin films were grown by recently developed\nmultilayer solid phase epitaxy. The ionic state of Ce was confirmed to be 3+ by\nx-ray photoelectron spectroscopy, corresponding to the electronic configuration\nof [Xe]4f1. Electrical resistivity showed the nonmonotonic temperature\ndependence with a sharp resistivity maximum, concomitant with a magnetization\nkink at 10 K, suggesting antiferromagnetic transition. In addition,\nmagnetoresistance showed a large angular-dependent magnetoresistance. These\nresults imply that carrier transport in the Bi2- square net could be influenced\nby magnetic ordering in the Ce-O layer owing to its unique layered structure\n[Bi2-/(Ce2O2)2+], particularly in the form of epitaxial thin films."
    },
    {
        "anchor": "Magnetically tunable dielectric materials: The coupling between localized spins and phonons can lead to shifts in the\ndielectric constant of insulating materials at magnetic ordering transitions.\nStudies on isostructural SeCuO3 (ferromagnetic) and TeCuO3 (antiferromagnetic)\nillustrate how the q-dependent spin-spin correlation function couples to phonon\nfrequencies leading to a shift in the dielectric constant. A model is discussed\nfor this spin-phonon coupling. The magnetodielectric coupling in multiferroic\nmaterials can be very large at a ferroelectric transition temperature. This\ncoupling is investigated in the recently identified multiferroic Ni3V2O8.",
        "positive": "Unfolding method for the first-principles LCAO electronic structure\n  calculations: Unfolding the band structure of a supercell to a normal cell enables us to\ninvestigate how symmetry breakers such as surfaces and impurities perturb the\nband structure of the normal cell. We generalize the unfolding method,\noriginally developed based on Wannier functions, to the linear combination of\natomic orbitals (LCAO) method, and present a general formula to calculate the\nunfolded spectral weight. The LCAO basis set is ideal for the unfolding method\nbecause of the invariance that basis functions allocated to each atomic species\nare invariant regardless of existence of surface and impurity. The unfolded\nspectral weight is well defined by the property of the LCAO basis functions. In\nexchange for the property, the non-orthogonality of the LCAO basis functions\nhas to be taken into account. We show how the non-orthogonality can be properly\nincorporated in the general formula. As an illustration of the method, we\ncalculate the dispersive quantized spectral weight of ZrB2 slab and show strong\nspectral broadening in the out-of-plane direction, demonstrating the usefulness\nof the unfolding method."
    },
    {
        "anchor": "Unexpected resonant response in [Fe(001)/Cr(001)]_(10) /MgO(001)\n  multilayers in magnetic field: We observed unexpected resonant response in [Fe/Cr]_(10) multilayers\nepitaxially grown on MgO(100) substrates which exists only when both ac current\nand dc magnetic field are simultaneously applied. The magnitude of the\nresonances is determined by the multilayer magnetization proving their\nintrinsic character. The reduction of interface epitaxy leads to non-linear\ndependence of the magnitude of resonances on the alternating current density.\nWe speculate that the existence of the interface transition zone could\nfacilitate the subatomic vibrations in thin metallic films and multilayers\ngrown on bulk insulating substrates.",
        "positive": "Multispectral time-resolved energy-momentum microscopy using\n  high-harmonic extreme ultraviolet radiation: A 790-nm-driven high-harmonic generation source with a repetition rate of 6\nkHz is combined with a toroidal-grating monochromator and a\nhigh-detection-efficiency photoelectron time-of-flight momentum microscope to\nenable time- and momentum-resolved photoemission spectroscopy over a spectral\nrange of $23.6$-$45.5$ eV with sub-100-fs time resolution. Three-dimensional\n(3D) Fermi surface mapping is demonstrated on graphene-covered Ir(111) with\nenergy and momentum resolutions of $\\lesssim$$100$ meV and $\\lesssim$$0.1$\n$\\r{A}^{-1}$, respectively. The table-top experiment sets the stage for\nmeasuring the $k_z$-dependent ultrafast dynamics of 3D electronic structure,\nincluding band structure, Fermi surface, and carrier dynamics in 3D materials\nas well as 3D orbital dynamics in molecular layers."
    },
    {
        "anchor": "First-Principles Study on Electron-Conduction Properties of C$_{60}$\n  Chains: The electron-conduction properties of fullerene chains are examined by\nfirst-principles calculations based on the density functional theory. The\nconductivity of the C$_{60}$ dimer is low owing to the constraint of the\njunction of the molecules on electron conduction, whereas the C$_{60}$ monomer\nexhibits a conductance of $\\sim$ 1 G$_0$. One of the three degenerate $t_{u1}$\nstates of C$_{60}$ is relevant to conduction and the contributions of the\nothers are small. In addition, we found a more interesting result that the\nconductance of the fullerene chain is drastically increased by encapsuling\nmetal atoms into cages.",
        "positive": "Comment on Structural Stability and Electronic Structure for\n  Li$_3$AlH$_6$: Density functional calculations of the electronic structure are used to\nelucidate the bonding of Li$_3$AlH$_6$. It is found that this material is best\ndescribed as ionic, and in particular that the [AlH$_6$]$^{3-}$ units are not\nreasonably viewed as substantially covalent."
    },
    {
        "anchor": "Benchmark Problems for Numerical Implementations of Phase Field Models: We present the first set of benchmark problems for phase field models that\nare being developed by the Center for Hierarchical Materials Design (CHiMaD)\nand the National Institute of Standards and Technology (NIST). While many\nscientific research areas use a limited set of well-established software, the\ngrowing phase field community continues to develop a wide variety of codes and\nlacks benchmark problems to consistently evaluate the numerical performance of\nnew implementations. Phase field modeling has become significantly more popular\nas computational power has increased and is now becoming mainstream, driving\nthe need for benchmark problems to validate and verify new implementations. We\nfollow the example set by the micromagnetics community to develop an evolving\nset of benchmark problems that test the usability, computational resources,\nnumerical capabilities and physical scope of phase field simulation codes. In\nthis paper, we propose two benchmark problems that cover the physics of solute\ndiffusion and growth and coarsening of a second phase via a simple spinodal\ndecomposition model and a more complex Ostwald ripening model. We demonstrate\nthe utility of benchmark problems by comparing the results of simulations\nperformed with two different adaptive time stepping techniques, and we discuss\nthe needs of future benchmark problems. The development of benchmark problems\nwill enable the results of quantitative phase field models to be confidently\nincorporated into integrated computational materials science and engineering\n(ICME), an important goal of the Materials Genome Initiative.",
        "positive": "False-positive and False-negative assignments of Topological Insulators\n  in Density-Functional Theory and Hybrids: Density-functional Theory (DFT) approaches have recently been used to judge\nthe topological order of various materials despite its well-known band gap\nunderestimation. Use of the more accurate quasi-particle GW approach reveals\nhere few cases where DFT identifications are false-positive, possibly\nmisguiding experimental searches of materials that are topological insulators\n(TI) in DFT but not expected to be TI in reality. We also present the case of\nfalse-positive due to the incorrect choice of crystal structures and adress the\nrelevancy of such choice of crystal structure with respect to the ground state\none and thermodynamical instability with respect to binary competing phases. We\nconclude that it is then necessary to consider both the correct ground state\ncrystal structure and the correct Hamiltonian in order to predict new TI."
    },
    {
        "anchor": "Structural, electronic and topological properties of 3D TmBi compound: Using density functional theory based methods we report the structural,\nelectronic and topological properties of the FCC crystal compound TmBi. This\nmaterial is found to be dynamically stable and shows a non magnetic semimetalic\ncharacter. By tuning the spin-orbit coupling, we observe a significant change\nin the band structure, and the occurrence of band inversion along $\\Gamma -X$\ndirection. The parity product at time-reversal invariant momentum points and\nthe Wannier charge center calculations provide a topological index $Z_{2}=1$ on\nthe $k_{j}=0$ plane (with $j=1,2$ and $3$) revealing the non trivial\ntopological character of TmBi. The existence of topologically protected surface\nstates of TmBi through the observation of a Dirac cones at $\\bar{X}$ point\nconfirm our finding. The present work could inspire platforms for exploring\nnovel topological states within the family of rare-earth monobismuthides.",
        "positive": "Maximally localized Wannier function within linear combination of\n  pseudo-atomic orbital method: Implementation and applications to\n  transition-metal-benzene complex: Construction of maximally localized Wannier functions (MLWFs) has been\nimplemented within the linear combination of pseudo-atomic orbital (LCPAO)\nmethod. Detailed analysis using MLWFs is applied to three closely related\nmaterials, single benzene (Bz) molecule, organometallic Vanadium-Bz infinite\nchain, and V$_2$Bz$_{3}$ sandwich cluster. Two important results come out from\nthe present analysis: 1) for the infinite chain, the validity of the basic\nassumption in the mechanism of Kanamori and Terakura for the ferromagnetic (FM)\nstate stability is confirmed; 2) for V$_2$Bz$_3$, an important role played by\nthe difference in the orbital energy between the edge Bzs and the middle Bz is\nnewly revealed: the on-site energy of p$\\delta$ states of edge Bzs is higher\nthan that of middle Bz, which further reduces the FM stability of V$_2$Bz$_3$."
    },
    {
        "anchor": "Absorption mechanism of dopamine/DOPAC modified TiO 2 nanoparticles by\n  time-dependent density functional theory calculations: Donor-modified TiO 2 nanoparticles are interesting hybrid systems shifting\nthe absorption edge of this semiconductor from the ultra-violet to the visible\nor infrared light spectrum, which is a benefit for several applications ranging\nfrom photochemistry, photocatalysis, photovoltaics, or photodynamic therapy.\nHere, we investigate the absorption properties of two catechol-like molecules,\ni.e. dopamine and DOPAC ligands, when anchored to a spherical anatase TiO 2\nnanoparticle of realistic size (2.2 nm), by means of time-dependent density\nfunctional theory calculations. By the differential absorbance spectra with the\nbare nanoparticle, we show how it is possible to determine the injection\nmechanism. Since new low-energy absorption peaks are observed, we infer a\ndirect charge transfer injection, which, unexpectedly, does not involve the\nlowest energy conduction band states. We also find that the more perpendicular\nthe molecular benzene ring is to the surface, the more intense is the\nabsorption, which suggests aiming at high molecular packing in the synthesis.\nThrough a comparative investigation with a flat TiO 2 surface model, we unravel\nboth the curvature and coverage effects.",
        "positive": "Mechanical buckling induced periodic kinking/stripe microstructures in\n  mechanically peeled graphite flakes from HOPG: Mechanical exfoliation is a widely used method to isolate high quality\ngraphene layers from bulk graphite. In our recent experiments, some ordered\nmicrostructures, consisting of a periodic alternation of kinks and stripes,\nwere observed in thin graphite flakes that were mechanically peeled from highly\noriented pyrolytic graphite (HOPG). A theoretical model is presented in this\npaper to understand the formation of such ordered microstructures, based on\nelastic buckling of a graphite flake being subjected to a bending moment. The\nwidth of the stripes predicted from this model agrees reasonably well with our\nexperimental measurements."
    },
    {
        "anchor": "Quantitative strain analysis of InAs/GaAs quantum dot materials: Geometric phase analysis has been applied to high resolution aberration\ncorrected (scanning) transmission electron microscopy images of InAs/GaAs\nquantum dot (QD) materials. We show quantitatively how the lattice mismatch\ninduced strain varies on the atomic scale and tetragonally distorts the lattice\nin a wide region that extends several nanometers into the GaAs spacer layer\nbelow and above the QDs. Finally, we show how V-shaped dislocations originating\nat the QD/GaAs interface efficiently remove most of the lattice mismatch\ninduced tetragonal distortions in and around the QD.",
        "positive": "Phase Transition of the Uniaxial Disordered Ferroelectric\n  Sr$_{0.61}$Ba$_{0.39}$Nb$_2$O$_6$: We report a neutron scattering study of a ferroelectric phase transition in\nSr$_{0.61}$Ba$_{0.39}$Nb$_2$O$_6$ (SBN-61). The ferroelectric polarization is\nalong the crystallographic $c$-axis but the transverse acoustic branch\npropagating along the $<$1, 1, 0$>$ direction does not show any anomaly\nassociated with the this transition. We find no evidence for a soft transverse\noptic phonon. We do, however, observe elastic diffuse scattering. The intensity\nof this scattering increases as the sample is cooled from a temperature well\nabove the phase transition. The susceptibility associated with this diffuse\nscattering follows well the anomaly of the dielectric permittivity of SBN-61.\nBelow T$_\\mathrm{c}$ the shape of this scattering is consistent with the\nscattering expected from ferroelectric domain walls. Our results suggest that\ndespite apparent chemical disorder SBN-61 behaves as a classic order-disorder\nuniaxial ferroelectric with critical fluctuations in the range $<10^{-11}$ s."
    },
    {
        "anchor": "Polarons in Carbon Nanotubes: We use ab initio total-energy calculations to predict the existence of\npolarons in semiconducting carbon nanotubes (CNTs). We find that the CNTs' band\nedge energies vary linearly and the elastic energy increases quadratically with\nboth radial and with axial distortions, leading to the spontaneous formation of\npolarons. Using a continuum model parametrized by the ab initio calculations,\nwe estimate electron and hole polaron lengths, energies and effective masses\nand analyze their complex dependence on CNT geometry. Implications of polaron\neffects on recently observed electro- and opto-mechanical behavior of CNTs are\ndiscussed.",
        "positive": "Large Magnetoresistance and Weak Antilocalization in V1-delta Sb2 Single\n  Crystal: The binary pnictide semimetals have attracted considerable attention due to\ntheir fantastic physical properties that include topological effects, negative\nmagnetoresistance, Weyl fermions and large non-saturation magnetoresistance. In\nthis paper, we have successfully grown the high-quality V1-deltaSb2 single\ncrystals by Sb flux method and investigated their electronic transport\nproperties. A large positive magnetoresistance that reaches 477% under a\nmagnetic field of 12 T at T = 1.8 K was observed. Notably, the\nmagnetoresistance showed a cusp-like feature at the low magnetic fields and\nsuch feature weakened gradually as the temperature increased, which indicated\nthe presence of weak antilocalization effect (WAL). The angle-dependent\nmagnetoconductance and the ultra-large prefactor alpha extracted from the\nHikami-Larkin-Nagaoka equation revealed that the WAL effect is a 3D bulk effect\noriginated from the three-dimensional bulk spin-orbital coupling."
    },
    {
        "anchor": "Electron and Hole Mobility of SnO2 from Full-Band Electron-Phonon and\n  Ionized Impurity Scattering Computations: Mobility is a key parameter for SnO2, which is extensively studied as a\npractical transparent oxide n-type semiconductor. In experiments, the mobility\nof electrons in bulk SnO2 single crystals varies from 70 to 260 cm2V-1s-1 at\nroom temperature. Here, we calculate the mobility as limited by electron-phonon\nand ionized impurity scattering by coupling the Boltzmann transport equation\nwith density functional theory electronic structures. The linearized Boltzmann\ntransport equation is solved numerically beyond the commonly employed constant\nrelaxation-time approximation by taking into account all energy and momentum\ndependencies of the scattering rates. Acoustic deformation potential and polar\noptical phonons are considered for electron-phonon scattering, where polar\noptical phonon scattering is found to be the main factor which determines the\nmobility of both electrons and holes at room temperature. The calculated\nphonon-limited electron mobility is found to be 265 cm2V-1s-1, whereas that of\nholes is found to be 7.6 cm2V-1s-1. We present the mobility as a function of\nthe carrier concentration, which shows the upper mobility limit. The large\ndifference between the mobilities of n-type and p-type SnO2 is a result of the\ndifferent effective masses between electrons and holes.",
        "positive": "Prediction of magnetic moment collapse in ZrFe$_2$ under hydrostatic\n  pressure: Electronic structure and magnetic properties of ZrFe$_2$ with a cubic Laves\nphase are investigated by calculations based on the density functional theory.\nThe total magnetic moment (m) of 3.14 $\\mu_B$ per formula unit (\\emph{f.u.}) is\nobtained at the experimental lattice constant (7.06 \\AA), which is larger than\n3.06 $\\mu_B$/\\emph{f.u.} obtained at the theoretical equilibrium lattice\nconstant (6.85 \\AA). The localized $3d$ magnetic moment is in negative\ndiffusive sp background moment. We predict a two-step magnetic collapse under\npressure: one is from 3.06 $\\mu_B$/\\emph{f.u.} to 1.26 $\\mu_B$/\\emph{f.u.} at\nabout 3.6 GPa, and the other is from 0.5 $\\mu_B$/\\emph{f.u.} to nonmagnetic\nstate at about 15 GPa. We understand this process by the changes of density of\nstates. The magnetic moment decreases under the pressure in the vicinity of the\nexperimental lattice constant with $d\\ln m/dp=-0.038$ GPa$^{-1}$. The\nspontaneous volume magnetostriction is 0.015. We suggest that the Invar effect\nof this alloy may be understood when considering the magnetic moment variation\naccording to the Weiss $2\\gamma$-model."
    },
    {
        "anchor": "Magnetic cooling at Risoe DTU: Magnetic refrigeration at room temperature is of great interest due to a\nlong-term goal of making refrigeration more energy-efficient, less noisy and\nfree of any environmentally hostile materials. A refrigerator utilizing an\nactive magnetic regenerator (AMR) is based on the magnetocaloric effect, which\nmanifests itself as a temperature change in magnetic materials when subjected\nto a varying magnetic field. In this work we present the current state of\nmagnetic refrigeration research at Risoe DTU with emphasis on the numerical\nmodeling of an existing AMR test machine. A 2D numerical heat-transfer and\nfluid-flow model that represents the experimental setup is presented.\nExperimental data of both no-heat load and heat load situations are compared to\nthe model. Moreover, results from the numerical modeling of the permanent\nmagnet design used in the system are presented.",
        "positive": "Effect of Site-disorder, Off-stoichiometry and Epitaxial Strain on the\n  Optical Properties of Magnetoelectric Gallium Ferrite: We present a combined experimental-theoretical study demonstrating the role\nof site disorder, off-stoichiometry and strain on the optical behavior of\nmagnetoelectric gallium ferrite. Optical properties such as band-gap,\nrefractive indices and dielectric constants were experimentally obtained by\nperforming ellipsometric studies over the energy range 0.8 eV to 4.2 eV on\npulsed laser deposited epitaxial thin films of stoichiometric gallium ferrite\nwith b-axis orientation and the data was compared with theoretical results.\nCalculations on the ground state structure show that the optical activity in\nGaFeO3 arises primarily from O2p-Fe3d transitions. Further, inclusion of site\ndisorder and epitaxial strain in the ground state structure significantly\nimproves the agreement between the theory and the room temperature experimental\ndata substantiating the presence of site-disorder in the experimentally derived\nstrained GaFeO3 films at room temperature. We attribute the modification of the\nground state optical behavior upon inclusion of site disorder to the\ncorresponding changes in the electronic band structure, especially in Fe3d\nstates leading to a lowered band-gap of the material."
    },
    {
        "anchor": "AlphaCrystal: Contact map based crystal structure prediction using deep\n  learning: Crystal structure prediction is one of the major unsolved problems in\nmaterials science. Traditionally, this problem is formulated as a global\noptimization problem for which global search algorithms are combined with first\nprinciple free energy calculations to predict the ground-state crystal\nstructure given only a material composition or a chemical system. These ab\ninitio algorithms usually cannot exploit a large amount of implicit\nphysicochemical rules or geometric constraints (deep knowledge) of atom\nconfigurations embodied in a large number of known crystal structures. Inspired\nby the deep learning enabled breakthrough in protein structure prediction,\nherein we propose AlphaCrystal, a crystal structure prediction algorithm that\ncombines a deep residual neural network model that learns deep knowledge to\nguide predicting the atomic contact map of a target crystal material followed\nby reconstructing its 3D crystal structure using genetic algorithms. Based on\nthe experiments of a selected set of benchmark crystal materials, we show that\nour AlphaCrystal algorithm can predict structures close to the ground truth\nstructures. It can also speed up the crystal structure prediction process by\npredicting and exploiting the predicted contact map so that it has the\npotential to handle relatively large systems. We believe that our deep learning\nbased ab initio crystal structure prediction method that learns from existing\nmaterial structures can be used to scale up current crystal structure\nprediction practice. To our knowledge, AlphaCrystal is the first neural network\nbased algorithm for crystal structure contact map prediction and the first\nmethod for directly reconstructing crystal structures from materials\ncomposition, which can be further optimized by DFT calculations.",
        "positive": "Calculation of the incremental stress-strain relation of a polygonal\n  packing: The constitutive relation of the quasi-static deformation on two dimensional\npacked samples of polygons is calculated using molecular dynamic simulations.\nThe stress values at which the system remains stable are bounded by a failure\nsurface, that shows a power law dependence on the pressure. Below the failure\nsurface, non linear elasticity and plastic deformation are obtained, which are\nevaluated in the framework of the incremental linear theory. The results shows\nthat the stiffness tensor can be directly related to the micro-contact\nrearrangements. The plasticity obeys a non-associated flow rule, with a plastic\nlimit surface that does not agree with the failure surface."
    },
    {
        "anchor": "Phase diagram and polarization of stable phases of\n  (Ga$_{1-x}$In$_x$)$_2$O$_3$: Using density-functional ab initio calculations, we provide a revised phase\ndiagram of (Ga$_{1-x}$In$_{x})_2$O$_3$. Three phases --monoclinic, hexagonal,\ncubic bixbyite-- compete for the ground state. In particular, in the\n$x$$\\sim$0.5 region we expect coexistence of hexagonal, $\\beta$, and bixbyite\n(the latter separating into binary components). Over the whole $x$ range,\nmixing occurs in three disconnected regions, and non-mixing in two additional\ndistinct regions. We then explore the permanent polarization of the various\nphases, finding that none of them is polar at any concentration, despite the\npossible symmetry reductions induced by alloying. On the other hand, we find\nthat the $\\varepsilon$ phase of Ga$_2$O$_3$ stabilized in recent growth\nexperiments is pyroelectric --i.e. locked in a non-switchable polarized\nstructure-- with ferroelectric-grade polarization and respectable piezoelectric\ncoupling. We suggest that this phase could be used profitably to produce\nhigh-density electron gases in transistor structures.",
        "positive": "Mining Insights on Metal-Organic Framework Synthesis from Scientific\n  Literature Texts: Identifying optimal synthesis conditions for metal-organic frameworks (MOFs)\nis a major challenge that can serve as a bottleneck for new materials discovery\nand development. Trial-and-error approach that relies on a chemist's intuition\nand knowledge has limitations in efficiency due to the large MOF synthesis\nspace. To this end, 47,187 number of MOF were data mined using our in-house\ndeveloped code to extract their synthesis information in 28,565 MOF papers. The\njoint machine learning/rule-based algorithm yields an average F1 score of 90.3\n% across different synthesis parameters (i.e. metal precursors, organic\nprecursors, solvents, temperature, time, composition). From this data set, a PU\nlearning algorithm was developed to predict synthesis of a given MOF material\nusing synthesis conditions as inputs, and this algorithm successfully predicted\nsuccessful synthesis in 83.1 % of the synthesized data in the test set.\nFinally, our model correctly predicted three amorphous MOFs (with their\nrepresentative experimental synthesis condition) as having low synthesizability\nscores while the counterpart crystalline MOFs showed high synthesizability\nscores. Our results show that big data extracted from the texts of MOF papers\ncan be used to rationally predict synthesis conditions for these materials,\nwhich can accelerate the speed in which new MOFs are synthesized."
    },
    {
        "anchor": "Density Functional Modeling and Total Scattering Analysis of the Atomic\n  Structure of a Quaternary CaO-MgO-Al2O3-SiO2 (CMAS) Glass: Uncovering the\n  Local Environment of Magnesium: Quaternary CaO-MgO-Al2O3-SiO2 glasses are important constituents of the\nEarth's lower crust and mantle, and they also have important industrial\napplications such as in metallurgical processes, concrete production and\nemerging low-CO2 cement technologies. In particular, these applications rely\nheavily on the composition-structure-reactivity relationships for CMAS glasses,\nwhich are not yet well established. In this study, we developed a robust method\nthat combines force-field molecular dynamics (MD) simulations and density\nfunctional theory (DFT) calculations with X-ray/neutron scattering experiments\nto resolve the atomic structure of a CMAS glass. The final structural\nrepresentation generated using this method is not only thermodynamically\nfavorable (according to DFT calculations) but also agrees with experiments\n(including X-ray/neutron scattering data as well as literature data). Detailed\nanalysis of the final structure (including partial pair distribution functions,\ncoordination number, oxygen environment) enabled existing discrepancies in the\nliterature to be reconciled and has revealed new structural information on the\nCMAS glass, specifically, (i) the unambiguous assignment of medium-range atomic\nordering, (ii) the preferential role of Ca atoms as charge compensators and Mg\natoms as network modifiers, (iii) the proximity of Mg atoms to free oxygen\nsites, and (iv) clustering of Mg atoms. Overall, this new structural\ninformation will enhance our mechanistic understanding on CMAS glass\ndissolution behavior, including dissolution-related mechanisms occurring during\nthe formation of low-CO2 cements.",
        "positive": "Existence of negative differential thermal conductance in\n  one-dimensional diffusive thermal transport: We show that in a finite one-dimensional (1D) system with diffusive thermal\ntransport described by the Fourier's law, negative differential thermal\nconductance (NDTC) cannot occur when the temperature at one end is fixed. We\ndemonstrate that NDTC in this case requires the presence of junction(s) with\ntemperature dependent thermal contact resistance (TCR). We derive a necessary\nand sufficient condition for the existence of NDTC in terms of the properties\nof the TCR for systems with a single junction. We show that under certain\ncircumstances we even could have infinite (negative or positive) differential\nthermal conductance in the presence of the TCR. Our predictions provide\ntheoretical basis for constructing NDTC-based devices, such as thermal\namplifiers, oscillators and logic devices."
    },
    {
        "anchor": "Tuning electromagnetic properties of SrRuO3 epitaxial thin films via\n  atomic control of cation vacancies: Elemental defects in transition metal oxides is an important and intriguing\nsubject that result in modifications in variety of physical properties\nincluding atomic and electronic structure, optical and magnetic properties.\nUnderstanding the formation of elemental vacancies and their influence on\ndifferent physical properties is essential in studying the complex oxide thin\nfilms. In this study, we investigated the physical properties of epitaxial\nSrRuO3 thin films by systematically manipulating cation and/or oxygen\nvacancies, via changing the oxygen partial pressure (P(O2)) during the pulsed\nlaser epitaxy (PLE) growth. Ru vacancies in the low-P(O2)-grown SrRuO3 thin\nfilms induce lattice expansion with the suppression of the ferromagnetic TC\ndown to ~120 K. Sr vacancies also disturb the ferromagnetic ordering, even\nthough Sr is not a magnetic element. Our results indicate that both A and B\ncation vacancies in an ABO3 perovskite can be systematically engineered via\nPLE, and the structural, electrical, and magnetic properties can be tailored\naccordingly.",
        "positive": "Panel flutter characteristics of sandwich plates with CNT reinforced\n  face sheets using an accurate higher-order theory: In this paper, the flutter characteristics of sandwich panels with carbon\nnanotube (CNT) reinforced face sheets are investigated using QUAD-8 shear\nflexible element developed based on higher-order structural theory. The\nformulation accounts for the realistic variation of the displacements through\nthe thickness, the possible discontinuity in the slope at the interface, and\nthe thickness stretch affecting the transverse deflection. The in-plane and\nrotary inertia terms are also included in the formulation. The first-order high\nMach number approximation to linear potential flow theory is employed for\nevaluating the aerodynamic pressure. The solutions of the complex eigenvalue\nproblem, developed based on Lagrange's equation of motion are obtained using\nthe standard method for finding the eigenvalues. The accuracy of the present\nformulation is demonstrated considering the problems for which solutions are\navailable. A detailed numerical study is carried out to bring out the efficacy\nof the higher-order model over the first-order theory and also to examine the\ninfluence of the volume fraction of the CNT, core-to-face sheet thickness, the\nplate thickness and the aspect ratio, damping and the temperature on the\nflutter boundaries and the associated vibration modes."
    },
    {
        "anchor": "Solid-liquid interface free energy through metadynamics simulations: The solid-liquid interface free energy \\gamma sl is a key parameter\ncontrolling nucleation and growth during solidification and other phenomena.\nThere are intrinsic difficulties in obtaining accurate experimental values, and\nthe previous approaches to compute \\gamma sl with atomistic simulations are\ncomputationally demanding. We propose a new approach, which is to obtain \\gamma\nsl from a free energy map of the phase transition reconstructed by\nmetadynamics. We apply this to the benchmark case of a Lennard-Jones potential\nand the results confirm the most reliable data obtained previously. We\ndemonstrate several advantages of our new approach: it is simple to implement,\nrobust and free of hysteresis problems, it allows a rigorous and unbiased\nestimate of the statistical uncertainty and it returns a good estimate of of\nthe thermodynamic limit with system sizes of a just a few hundred atoms. It is\ntherefore attractive for using with more realistic and specific models of\ninteratomic forces.",
        "positive": "Two-Dimensional PN Monolayer Sheets with Fantastic Structures and\n  Properties: Three two-dimensional phosphorus nitride (PN) monolayer sheets (named as\n$\\alpha$-, $\\beta$-, and $\\gamma$-PN, respectively) with fantastic structures\nand properties are predicted based on first-principles calculations. The\n$\\alpha$-PN and $\\gamma$-PN are buckled structure, whereas $\\beta$-PN shows\npuckered characteristics. Their unique structures endows these atomic PN sheets\nwith high dynamic stabilities and anisotropic mechanical properties. They are\nall indirect semiconductors and their band gap sensitively depends on the\nin-plane strain. Moreover, the nanoribbons patterned from these three PN\nmonolayers demonstrate remarkable quantum size effect. Particularly, the Zigzag\n$\\alpha$-PN nanoribbon shows size-dependent ferromagnetism. Their significant\nproperties show potential in nano-electronics. The synthesis of the three\nphases of PN monolayer sheets is proposed theoretically, which is deserved to\nfurther study in experiments."
    },
    {
        "anchor": "Dynamical charge and pseudospin currents in graphene and possible Cooper\n  pair formation: Based on the quantum kinetic equations for systems with SU(2) structure,\nregularization-free density and pseudospin currents are calculated in graphene\nrealized as the infinite mass-limit of electrons with quadratic dispersion and\na proper spin-orbit coupling. Correspondingly the currents possess no\nquasiparticle part but only anomalous parts. The intraband and interband\nconductivities are discussed with respect to magnetic fields and magnetic\ndomain puddles. It is found that the magnetic field and meanfield of domains\ncan be represented by an effective Zeeman field. For large Zeeman fields the\ndynamical conductivities become independent of the density and are universal in\nthis sense. The different limits of vanishing density, relaxation, frequency,\nand Zeeman field are not interchangeable. The optical conductivity agrees well\nwith the experimental values using screened impurity scattering and an\neffective Zeeman field. The universal value of Hall conductivity is shown to be\nmodified due to the Zeeman field. The pseudospin current reveals an anomaly\nsince a quasiparticle part appears though it vanishes for particle currents.\nThe density and pseudospin response functions to an external electric field are\ncalculated and the dielectric function is discussed with respect to collective\nexcitations. A frequency and wave-vector range is identified where the\ndielectric function changes sign and the repulsive Coulomb potential becomes\neffectively attractive allowing Cooper pairing.",
        "positive": "Dependence of Magnetic Anisotropy and Magnetoresistance of\n  Ni81Fe19-Films on Annealing: Permalloy (Py:Ni81Fe19) exhibits an anisotropic magnetoresistance (AMR) which\nis very often used to read magnetic signals from storage devices. Py-films of\nthickness 20nm were prepared by dc-magnetron sputtering in a magnetic field\nonto thermally oxidized Si-wafers and annealed ex situ at temperatures up to\n1000K in order to investigate the dependence of the magnetic anisotropy and the\nAMR on heat treatments. The films exhibit an uniaxial anisotropy after\npreparation which changes during annealing above 520K. The AMR along the former\nmagnetically easy axis as well as the corresponding field sensitivity are\nincreased by a heat treatment around 700K reaching maxima of about 8% and a\nmaximum sensitivity of 1.5%/Oe, respectively. We discuss possible sources for\nthe change in anisotropy, i.e. strain effects, inhomogeneities, and changes of\nthe local atomic order."
    },
    {
        "anchor": "Anatomy of Dzyaloshinskii-Moriya Interaction at Co/Pt Interfaces: The Dzyaloshinskii-Moriya Interaction (DMI) between spins is induced by\nspin-orbit coupling in magnetic materials lacking inversion symmetry. DMI is\nrecognized to play a crucial role at the interface between ferromagnetic (FM)\nand heavy nonmagnetic (NM) metals to create topological textures called\nmagnetic skyrmions which are very attractive for ultra-dense information\nstorage and spintronic devices. DMI also plays an essential role for fast\ndomain wall (DW) dynamics driven by spin-orbit torques. Here, we present first\nprinciples calculations which clarify the main features and microscopic\nmechanisms of DMI in Co/Pt bilayers. DMI is found to be predominantly located\nat the interfacial Co layer, originating from spin-orbit energy provided by the\nadjacent NM layer. Furthermore, no direct correlation is found between DMI and\nproximity induced magnetism in Pt. These results clarify underlying mechanisms\nof DMI at FM/NM bilayers and should help optimizing material combinations for\nskyrmion- and DW-based storage and memory devices.",
        "positive": "SUePDF: a program to obtain quantitative pair distribution function from\n  electron diffraction data: SUePDF is a graphic-user-interface program written in MATLAB to achieve\nquantitative pair distribution functions (PDF) from electron diffraction data.\nThe program facilitates the structural studies of amorphous materials and small\nnanoparticles based on electron diffraction data from transmission electron\nmicroscopes (TEMs). It is based on the physics of electron scattering as well\nas the total scattering methodology. A method of background modelling is\nintroduced to treat the intensity tail of the direct beam, inelastic scattering\nand incoherent multiple scattering. Kinematical electron scattering intensity\nis scaled using the electron scattering factors. The PDFs obtained after\nFourier transforms are normalized with respect to number density, nanoparticle\nform factor, and the non-negativity of probability density. SUePDF is\ndistributed as free software for academic users."
    },
    {
        "anchor": "Structural insight using anomalous XRD into Mn2CoAl Heusler alloy films\n  grown by magnetron sputtering, IBAS and MBE techniques: Inverse Heusler alloy Mn2CoAl thin films, known as a spin-gapless\nsemiconductor (SGS), grown by three different methods: ultra-high vacuum\nmagnetron spattering, Ar-ion beam assisted sputtering, and molecular beam\nepitaxy, are investigated by comparing their electric transport properties,\nmicrostructures and atomic-level structures. Of the samples, the Mn2CoAl thin\nfilm grown by MBE consists of Mn- and Co-rich phases, the structures of which\nare determined to be the L21B-type and disordered L21-type, respectively,\naccording to anomalous XRD analysis. None of them forms the XA-type structure\nexpected for SGS Heusler alloy, although they all show SGS characteristics. We\nsuggest, to validate SGS characteristics, it is necessary to extract not only\nmagnetic and electric transport properties but also information about\nmicrostructures and atomic-scale structures of the films including defects such\nas atomic swap.",
        "positive": "Modeling warm dense matter formation within tight binding approximation: This contribution discusses challenges in the modeling of formation of the\nwarm dense matter (WDM) state in solids exposed to femtosecond X-ray\nfree-electron laser pulses. It is based upon our previously reported code XTANT\n(X-ray-induced Thermal And Nonthermal Transition; N. Medvedev et. al, 4open 1,\n3, 2018), which combines tight-binding (TB) molecular dynamics for atoms with\nMonte Carlo modeling of high-energy electrons and core-holes, and Boltzmann\ncollision integrals for nonadiabatic electron-ion coupling. The current version\nof the code, XTANT-3, includes LCAO basis sets sp3, sp3s*, and sp3d5, and can\noperate with both orthogonal and nonorthogonal Hamiltonians. It includes the TB\nparameterizations by Goodwin et al., a transferrable version of Vogl's et al.\nTB, NRL, and DFTB. Considering that other modules of the code are applicable to\nany chemical element, this makes XTANT-3 capable of treating a large variety of\nmaterials. In order to extend it to the WDM regime, a few limitations that must\nbe overcome are discussed here: short-range repulsion potential must be\nsufficiently strong; basis sets must span large enough energy space within the\nconduction band; dependence of the electronic scattering cross sections on the\nelectronic and atomic temperatures and structure needs to be considered.\nDirections at solving these issues are outlined in this proceeding."
    },
    {
        "anchor": "Hydrogen-enhanced local plasticity in aluminum: an ab initio study: Dislocation core properties of Al with and without H impurities are studied\nusing the Peierls-Nabarro model with parameters determined by ab initio\ncalculations. We find that H not only facilitates dislocation emission from the\ncrack tip but also enhances dislocation mobility dramatically, leading to\nmacroscopically softening and thinning of the material ahead of the crack tip.\nWe observe strong binding between H and dislocation cores, with the binding\nenergy depending on dislocation character. This dependence can directly affect\nthe mechanical properties of Al by inhibiting dislocation cross-slip and\ndeveloping slip planarity.",
        "positive": "Introduction to Electromagnetic Theory and the Physics of Conducting\n  Solids: The purpose of this sophomore-level textbook is twofold: to introduce the\nstudent to classical electrodynamics and, at the same time, explain in simple\nterms the quantum theory of conducting substances (in particular, the solid\nones). The presentation sacrifices mathematical detail (wherever necessary) in\nfavor of pedagogical efficiency. The theory of vector fields is briefly\npresented in a separate chapter, aiding the student to cope with the\nmathematical challenges of Maxwell's theory."
    },
    {
        "anchor": "Toxicity of Carbon Nanomaterials: The outstanding multidisciplinary applicability of nanomaterials has paved\nthe path for the rapid advancement of nanoscience during the last few decades.\nSuch technological progress subsequently results in an inevitable environmental\nexposure of nanomaterials. Presently, nanomaterials are employed in an\nextensive range of commercial products. Safe and sustainable incorporation of\nnanomaterials in industrial products requires a profound and comprehensive\nunderstanding of their potential toxicity. Among different nanomaterials,\ncarbon nanomaterials marked its notable superiority toward the development of\nstate-of-the-art nanotechnology due to the significant contribution of each of\nthe carbon allotropes with varied dimensionality. The zero-dimensional\nfullerene, one-dimensional carbon nanotube, and two-dimensional graphene\npossess an exclusive combination of distinctive properties that are utilized in\nmost of the nanotechnology-based products nowadays. However, potential risk\nfactors are associated with the production and the use of carbon nanomaterials.\nConsequently, the number of studies regarding the assessment of the toxicity of\nthese nanomaterials has increased rapidly in the past decade. This chapter will\nsummarize the recent scientific efforts on the toxicity evaluation of different\ncarbon nanomaterials.",
        "positive": "Relaxor ferroelectric behavior and structural aspects of SrNaBi2Nb3O12\n  ceramics: SrNaBi2Nb3O12 powder was prepared via the conventional solid-state reaction\nmethod. X-ray structural studies confirmed the phase to be a three-layered\nmember of the Aurivillius family of oxides. SrNaBi2Nb3O12 (SNBN) ceramics\nexhibited the typical characteristics of relaxor ferroelectrics, associated\nwith broad and dispersive dielectric maxima. The variation of temperature of\ndielectric maxima (Tm) with frequency obeyed the Vogel-Fulcher relationship.\nRelaxor behavior was believed to be arising from the cationic disorder at\nA-site. Pinched ferroelectric hysteresis loops were observed well above Tm."
    },
    {
        "anchor": "Ferromagnetism in Cr-doped topological insulator TlSbTe2: We have synthesized a new ferromagnetic topological insulator by doping Cr to\nthe ternary topological-insulator material TlSbTe2. Single crystals of\nTl_{1-x}Cr_{x}SbTe2 were grown by a melting method and it was found that Cr can\nbe incorporated into the TlSbTe2 matrix only within the solubility limit of\nabout 1%. The Curie temperature \\theta_c was found to increase with the Cr\ncontent but remained relatively low, with the maximum value of about 4 K. The\neasy axis was identified to be the c-axis and the saturation moment was 2.8\n\\mu_B (Bohr magneton) at 1.8 K. The in-plane resistivity of all the samples\nstudied showed metallic behavior with p-type carriers. Shubnikov-de Hass (SdH)\noscillations were observed in samples with the Cr-doping level of up to 0.76%.\nWe also tried to induce ferromagnetism in TlBiTe2 by doping Cr, but no\nferromagnetism was observed in Cr-doped TlBiTe2 crystals within the solubility\nlimit of Cr which turned out to be also about 1%.",
        "positive": "Magnetic Magnetoelectric and Magnetoelastic Properties of new\n  multiferroic material NdFe3(BO3)4: Complex experimental and theoretical study of the magnetic, magnetoelectric,\nand magnetoelastic properties of neodymium iron borate NdFe3(BO3)4 along\nvarious crystallographic directions have been carried out in strong pulsed\nmagnetic fields up to 230 kOe in a temperature range of 4.2-50 K. It has been\nfound that neodymium iron borate, as well as gadolinium iron borate, is a\nmultiferroic. It has much larger (above 3 10^(-4) C/m^2) electric polarization\ncontrolled by the magnetic field and giant quadratic magnetoelectric effect.\nThe exchange field between the rare-earth and iron subsystems (~50 kOe) has\nbeen determined for the first time from experimental data. The theoretical\nanalysis based on the magnetic symmetry and quantum properties of the Nd ion in\nthe crystal provides an explanation of an unusual behavior of the\nmagnetoelectric and magnetoelastic properties of neodymium iron borate in\nstrong magnetic fields and correlation observed between them."
    },
    {
        "anchor": "Self-optimizing layered hydrogen evolution catalyst with high\n  basal-plane activity: Hydrogen is a promising energy carrier and key agent for many industrial\nchemical processes1. One method for generating hydrogen sustainably is via the\nhydrogen evolution reaction (HER), in which electrochemical reduction of\nprotons is mediated by an appropriate catalyst-traditionally, an expensive\nplatinum-group metal. Scalable production requires catalyst alternatives that\ncan lower materials or processing costs while retaining the highest possible\nactivity. Strategies have included dilute alloying of Pt2 or employing less\nexpensive transition metal alloys, compounds or heterostructures (e.g., NiMo,\nmetal phosphides, pyrite sulfides, encapsulated metal nanoparticles)3-5.\nRecently, low-cost, layered transition-metal dichalcogenides (MX2)6 based on\nmolybdenum and tungsten have attracted substantial interest as alternative HER\ncatalysts7-11. These materials have high intrinsic per-site HER activity;\nhowever, a significant challenge is the limited density of active sites, which\nare concentrated at the layer edges.8,10,11. Here we use theory to unravel\nelectronic factors underlying catalytic activity on MX2 surfaces, and leverage\nthe understanding to report group-5 MX2 (H-TaS2 and H-NbS2) electrocatalysts\nwhose performance instead derives from highly active basal-plane sites. Beyond\nexcellent catalytic activity, they are found to exhibit an unusual ability to\noptimize their morphology for enhanced charge transfer and accessibility of\nactive sites as the HER proceeds. This leads to long cycle life and practical\nadvantages for scalable processing. The resulting performance is comparable to\nPt and exceeds all reported MX2 candidates.",
        "positive": "Tuneable local order in thermoelectric crystals: Although crystalline solids are characterized by their periodic structures,\nsome are only periodic on average and deviate on a local scale. Distinct local\norderings can exist with identical periodic structures making their differences\nhidden to normal diffraction methods. Using x-ray scattering we investigate the\nthermoelectric half-Heusler, Nb1-xCoSb, with high vacancy concentrations, where\nsigns of local order have been attributed to differences in stoichiometry. We\nshow that the composition is actually always very close to x = 1/6 irrespective\nof nominal sample composition, and that the synthesis method controls the local\norder. The vacancy distribution is shown to follow a vacancy repulsion model,\nand local structural relaxations around the vacancies are characterized.\nControl over the local structure provides a new frontier for tuning material\nproperties."
    },
    {
        "anchor": "Elastic modeling of point-defects and their interaction: Different descriptions used to model a point-defect in an elastic continuum\nare reviewed. The emphasis is put on the elastic dipole approximation, which is\nshown to be equivalent to the infinitesimal Eshelby inclusion and to the\ninfinitesimal dislocation loop. Knowing this elastic dipole, a second rank\ntensor fully characterizing the point-defect, one can directly obtain the\nlong-range elastic field induced by the point-defect and its interaction with\nother elastic fields. The polarizability of the point-defect, resulting from\nthe elastic dipole dependence with the applied strain, is also introduced.\nParameterization of such an elastic model, either from experiments or from\natomic simulations, is discussed. Different examples, like elastodiffusion and\nbias calculations, are finally considered to illustrate the usefulness of such\nan elastic model to describe the evolution of a point-defect in a external\nelastic field.",
        "positive": "An Atom-Pair Bond Theory for the Alloying of Metals: We present an Atom-Pair Bond (APB) theory for the energy of a metallic bond\nbased on the ideas of covalent bonding proposed by Pauling. An expression is\nderived which accurately predicts the signs of the heats of formation of binary\nalloys. It also explains the characteristics of the Rajasekharan-Girgis lines\nand their ability to predict accurately concomitant and mutually exclusive\nstructure types in phase diagrams. Evidence is provided to show that the charge\ntransfer on the atom-pair bond which is central to the present theory decides\nthe experimentally observed volume changes on alloying."
    },
    {
        "anchor": "Tunable Semimetallic State in Compressive-strained SrIrO3 Films Revealed\n  by Transport Behaviors: Orthorhombic SrIrO3 is a typical spin-orbit-coupling correlated metal that\nshows diversified physical properties under the external stimuli. Here\nnonlinear Hall effect and weakly temperature-dependent resistance are observed\nin a SrIrO3 film epitaxially grown on SrTiO3 substrate. It infers that\northorhombic SrIrO3 is a semimetal oxide. However, linear Hall effect and\ninsensitive-temperature-dependent resistance are observed in SrIrO3 films grown\non (La,Sr)(Al,Ta)O3 (LSAT) substrates, suggesting a tunable semimetallic state\ndue to band structure change in SrIrO3 films under different compressive\nstrain. The mechanism of this evolution is explored in detail through\nstrain-state analysis by reciprocal space mapping and electron diffraction,\ncarrier density and mobility calculations, as well as electronic band structure\nevolution under compressive strain (predicted by tight-binding approximation).\nIt might suggest that the strain-induced band shift leads to the semimetallic\ntuning in the SrIrO3 film grown on from SrTiO3 to LSAT substrates. Our findings\nillustrate the tunability of SrIrO3 properties and pave the way to induce novel\nphysical states in SrIrO3 such as the proposed topological insulator state in\nheterostructures.",
        "positive": "Electric field-induced colossal electroresistance and its relaxation in\n  multiferroic La2NiMnO6: In this work, we report direct as well as pulsed electric field-induced\nresistivity switching and its relaxation in a multiferroic insulator La2NiMnO6.\nAt a fixed base temperature (Tb), the dc resistivity switches abruptly from a\nhigh to a low value, which is manifested as an upward jump in the dc current\ndensity (J) when the electric field (E) exceeds a threshold value Eth. The\nfractional change in the resistance is as much as 70 % at room temperature for\nEth = 95 V/cm. The Eth increases with lowering Tb and follows the relation\nEth(Tb) = Eth(0)exp[-Tb/T0], as similar to the behavior found in charge density\nwave systems. It is shown that the abrupt jump in J vanishes under pulsed\nelectric fields if the period between pulses is long enough. Surprisingly, a\nstep-like increase in J also occurs at a fixed dc electric field (Ec) and T =\nTb, above a threshold waiting time (tth). The tth decreases with increasing Ec\nand Tb. Simultaneous measurement of surface temperature during the J-E sweep\nand temporal studies suggest that conductive channels are created in an\ninsulating matrix due to the local self heating, and the coalescence of these\nchannels above a threshold E- field or time causes the observed anomalies in J.\nHowever, the dissipated Joule power (P = Ith2R) at the transition from high to\nlow resistive state in the sample decreases with lowering temperature, which\nsuggests that the Joule heating is the consequence of transition from the high\nto low resistance state rather than itself a driving force of the non linear\nelectrical transport. In addition, non linear J-E characteristics is also found\neven with a pulsed voltage sweep, which suggests that intrinsic mechanisms\nother than self heating is still active in this material."
    },
    {
        "anchor": "Oxygen vacancies in bulk and at neutral domain walls in hexagonal\n  YMnO$_3$: We use density functional calculations to investigate the accommodation and\nmigration of oxygen vacancies in bulk hexagonal YMnO$_3$, and to study\ninteractions between neutral ferroelectric domain walls and oxygen vacancies.\nOur calculations show that oxygen vacancies in bulk YMnO$_3$ are more stable in\nthe Mn-O layers than in the Y-O layers. Migration barriers of the planar oxygen\nvacancies are high compared to oxygen vacancies in perovskites, and to\npreviously reported values for oxygen interstitials in h-YMnO$_3$. The\ncalculated polarization decreases linearly with vacancy concentration, while\nthe out-of-plane lattice parameter expands in agreement with previous\nexperiments. In contrast with ferroelectric perovskites, oxygen vacancies are\nfound to be more stable in bulk than at domain walls. The tendency of oxygen\nvacancies to segregate away from neutral domain walls is explained by\nunfavorable Y-O bond lengths caused by the local strain field at the domain\nwalls.",
        "positive": "Quantum Unfolding: A program for unfolding electronic energy bands of\n  materials: We present Quantum Unfolding, a Fortran90 program for unfolding\nfirst-principles electronic energy bands. It unfolds energy bands accurately by\nhandling the Fourier components of Bloch wavefunctions, which are reconstructed\nfrom Wannier functions from Wannier90. Due to the wide application of Wannier90\npackage and the possibility of focusing only on the most important energy\nbands, the present code works very conveniently."
    },
    {
        "anchor": "Molecular Adsorption on Metal Surfaces with a van der Waals Density\n  Functional: The adsorption of 1,4-benzenediamine (BDA) on the Au(111) surface and\nazobenzene on the Ag(111) surface is investigated using density functional\ntheory (DFT) with a non-local density functional (vdW-DF) and a semi-local\nPerdew-Burke-Ernzerhof (PBE) functional. For BDA on Au(111), the inclusion of\nLondon dispersion interactions not only dramatically enhances the\nmolecule-substrate binding, resulting in adsorption energies consistent with\nexperimental results, but also significantly alters the BDA binding geometry.\nFor azobenzene on Ag(111), the vdW-DF produces superior adsorption energies\ncompared to those obtained with other dispersion corrected DFT approaches.\nThese results provide evidence for the applicability of the vdW-DF method and\nserves as a practical benchmark for the investigation of molecules adsorbed on\nnoble metal surfaces.",
        "positive": "Large thermoelectric figure of merit in graphene layered devices at low\n  temperature: Nanostructured materials have emerged as an alternative to enhance the figure\nof merit (ZT) of thermoelectric (TE) devices. Graphene exhibits a high\nelectrical conductivity (in-plane) that is necessary for a high ZT; however,\nthis effect is countered by its impressive thermal conductivity. In this work\nTE layered devices composed of electrochemically exfoliated graphene (EEG) and\na phonon blocking material such as poly (3,4-ethylenedioxythiophene)polystyrene\nsulfonate (PEDOT:PSS), polyaniline (PANI) and gold nanoparticles (AuNPs) at the\ninterface were prepared. The figure of merit, ZT, of each device was measured\nin the cross-plane direction using the Transient Harman Method (THM) and\ncomplemented with AFM-based measurements. The results show remarkable high ZT\nvalues (0.81 < ZT < 2.45) that are directly related with the topography,\nsurface potential, capacitance gradient and resistance of the devices at the\nnanoscale."
    },
    {
        "anchor": "Electron effective mass in unintentionally doped In$_{0.33}$Ga$_{0.67}$N\n  determined by mid-infrared optical Hall effect: Mid-infrared optical Hall effect measurements are used to determine the free\ncharge carrier parameters of an unintentionally doped wurtzite-structure\n$c$-plane oriented In$_{0.33}$Ga$_{0.67}$N epitaxial layer. Room temperature\nelectron effective mass parameters of $m^{*}_{\\bot}=(0.205 \\pm 0.013)~m_0$ and\n$m^{*}_{\\parallel}=(0.204 \\pm 0.016)~m_0$ for polarization perpendicular and\nparallel to the $c$-axis, respectively, were determined. The free electron\nconcentration was obtained as $(1.7 \\pm 0.2)\\times 10^{19}~$cm$^{-3}$. Within\nour uncertainty limits we detect no anisotropy for the electron effective mass\nparameter and we estimate the upper limit of the possible effective mass\nanisotropy is 7$\\%$. We discuss the influence of band nonparabolicity on the\nelectron effective mass parameter as a function of In content. The effective\nmass parameter is consistent with a linear interpolation scheme between the\nconduction band mass parameters in GaN and InN when the strong nonparabolicity\nin InN is included. The In$_{0.33}$Ga$_{0.67}$N electron mobility parameters\nwere found to be anisotropic supporting previous experimental findings for\nwurtzite-structure GaN, InN, and Al$_{x}$Ga$_{1-x}$N epitaxial layers with\n$c$-plane growth orientation.",
        "positive": "Topotactic Transition: A Promising Opportunity for Creating New Oxides: Topotactic transition is a structural phase change in a matrix crystal\nlattice mediated by the ordered loss/gain and rearrangement of atoms, leading\nto unusual coordination environments and metal atoms with rare valent states.\nAs early as in 1990s, low temperature hydride reduction was utilized to realize\nthe topotactic transition. Since then, topological transformations have been\ndeveloped via multiple approaches. Especially, the recent discovery of the\nNi-based superconductivity in infinite-layer nickelates has greatly boosted the\ntopotactic transition mean to synthesizing new oxides for exploring exotic\nfunctional properties. In this review, we have provided a detailed and\ngeneralized introduction to oxygen-related topotactic transition. The main body\nof our review include four parts: the structure-facilitated effects, the\nmechanism of the topotactic transition, some examples of topotactic transition\nmethods adopted in different metal oxides (V, Mn, Fe, Co, Ni) and the related\napplications. This work is to provide timely and thorough strategies to\nsuccessfully realize topotactic transitions for researchers who are eager to\ncreate new oxide phases or new oxide materials with desired functions."
    },
    {
        "anchor": "From first-order magneto-elastic to magneto-structural transition in\n  (Mn,Fe)1.95P0.50Si0.50 compounds: We report on structural, magnetic and magnetocaloric properties of\nMnxFe1.95-xP0.50Si0.50 (x > 1.10) compounds. With increasing the Mn:Fe ratio, a\nfirst-order magneto-elastic transition gradually changes into a first-order\nmagneto-structural transition via a second-order magnetic transition. The study\nalso shows that thermal hysteresis can be tuned by varying the Mn:Fe ratio.\nSmall thermal hysteresis (less than 1 K) can be obtained while maintaining a\ngiant magnetocaloric effect. This achievement paves the way for real\nrefrigeration applications using magnetic refrigerants.",
        "positive": "The Effect of Counterions on the Interactions of Charged Oligothiophenes: The functionality of conjugated polymer systems often relies on oxidations or\nreductions, in most cases mediated by the presence of counterions. The effect\nthat the common counterion hexafluorophosphate (PF6-) has on the intermolecular\ninteractions between charged oligothiophenes is investigated here using ab\ninitio quantum chemistry methods. Counterions are explicitly included in the\nsimulations of oxidized oligothiophenes and in the dimerization process. Our\ncalculations provide quantitative and qualitative insight into the\nintermolecular interactions in oligothiophene-counterion systems and show that\nthe intermolecular pi-stacking of oligothiophenes is not adversely affected by\nthe presence of counterions, and that in fact oligothiophene dimerization is\nfurther stabilized by their presence."
    },
    {
        "anchor": "Dielectric quantification of conductivity limitations due to nanofiller\n  size in conductive powders and nanocomposites: Conducting submicron particles are well-suited as filler particles in\nnon-conducting polymer matrices to obtain a conducting composite with a low\npercolation threshold. Going to nanometer-sized filler particles imposes a\nrestriction to the conductivity of the composite, due to the reduction of the\ndensity of states involved in the hopping process between the particles,\ncompared to its value within the crystallites. We show how those microscopic\nparameters that govern the charge-transport processes across many decades of\nlength scales, can accurately and consistently be determined by a range of\ndielectric-spectroscopy techniques from a few Hz to infrared frequencies. The\nmethod, which is suited for a variety of systems with restricted geometries, is\napplied to densely packed 7-nm-sized tin-oxide crystalline particles with\nvarious degree of antimony doping and the quantitative results unambiguously\nshow the role of the nanocrystal charging energy in limiting the hopping\nprocess.",
        "positive": "An SERS study of the galvanostatic sequence employed for the\n  electrochemical deposition of Copper in the fabrication of Interconnects: This paper reports the first study carried out by surface-enhanced Raman\nspectroscopy (SERS) during the galvanostatic electrodeposition (ECD) of copper\nfrom an acidic sulphate solution, in the presence of polyethylene glycol (PEG),\nbis-(3-sulfopropyl)-disulfide Na salt (SPS), benzyl-phenyl modified\npolyethyleneimine (BPPEI) and chloride ions. The analysis of SERS spectra\nrecorded during electrodeposition allowed to get an insight into the complex\ninterfacial behaviour of the organic blend, in terms of co-adsorption and\nreactivity. At open-circuit (OC), the additives co-adsorb on the copper\ncathode. Upon increasing the cathodic polarization, progressive SPS-scavenging\naction of PEG was observed. BPPEI is adsorbed in the entire process window and\ncathodic reaction products of PEG were identified. The joint action of the\norganic additives yields a continuous deposit with crystallites of submicron\ndimensions, as revealed by Scanning Electron Microscopy (SEM)."
    },
    {
        "anchor": "Experimental evidence of large-gap two-dimensional topological insulator\n  on the surface of ZrTe5: Two-dimensional (2D) topological insulators (TIs) with a large bulk band-gap\nare promising for experimental studies of the quantum spin Hall effect and for\nspintronic device applications. Despite considerable theoretical efforts in\npredicting large-gap 2D TI candidates, only few of them have been\nexperimentally verified. Here, by combining scanning tunneling\nmicroscopy/spectroscopy and angle-resolved photoemission spectroscopy, we\nreveal that the top monolayer of ZrTe5 crystals hosts a large band gap of ~100\nmeV on the surface and a finite constant density-of-states within the gap at\nthe step edge. Our first-principles calculations confirm the topologically\nnontrivial nature of the edge states. These results demonstrate that the top\nmonolayer of ZrTe5 crystals is a large-gap 2D TI suitable for topotronic\napplications at high temperature.",
        "positive": "A new look on the nature of high-spin to low-spin transition in Fe2O3: Iron sesquioxide (Fe2O3) displays pressure and temperature induced spin and\nstructural transitions. Our calculations show that, density functional theory\n(DFT), in the generalized gradient approximation (GGA) scheme, is capable of\ncapturing both the transitions. The ambient pressure corundum type phase\n(hematite or alpha-Fe2O3), having R_3c symmetry, gets distorted by the\napplication of pressure and transforms to a distorted corundum type or\nRh2O3(II) phase with Pbcn symmetry, in agreement with recent experiments. GGA +\nU calculations show the same trend but shift the transition pressures to higher\nvalues. Experimentally, the onset of the structural transition begins in the\nvicinity of the spin transition pressure and whether the system undergoes spin\ntransition in the corundum type (HP1) or in the Rh2O3(II) type (HP2) phase, is\nstill a controversial issue. With a relatively simple, but general, octahedral\nstructural parameter, Voct (the octahedral volume around iron ions), we show\nthat in order to acquire a low spin (LS) state from a high spin (HS) one, the\nsystem does not necessarily need to change the crystal structure. Rather, the\nspin transition is a phenomenon that concerns the cation octahedra and the spin\nstate of the system depends mainly on the value of Voct, which is governed by\ntwo distinct equations of state, separated by a well defined volume gap, for\nthe HS and LS states respectively. Analysis of the results on the basis of\noctahedral volume allows to sum up and bridge the gap between two experimental\nresults and thus provides a better description of the system in the region of\ninterest."
    },
    {
        "anchor": "Anisotropic Thermal Conductivity of 4H and 6H Silicon Carbide Measured\n  Using Time-Domain Thermoreflectance: Silicon carbide (SiC) is a wide bandgap (WBG) semiconductor with promising\napplications in high-power and high-frequency electronics. Among its many\nuseful properties, the high thermal conductivity is crucial. In this letter,\nthe anisotropic thermal conductivity of three SiC samples: n-type 4H-SiC\n(N-doped 1x10^19 cm-3), unintentionally doped (UID) semi-insulating (SI)\n4H-SiC, and SI 6H-SiC (V-doped 1x10^17 cm-3), is measured using femtosecond\nlaser based time-domain thermoreflectance (TDTR) over a temperature range from\n250 K to 450 K. We simultaneously measure the thermal conductivity parallel to\n(k_r) and across the hexagonal plane (k_z) for SiC by choosing the appropriate\nlaser spot radius and the modulation frequency for the TDTR measurements. For\nboth k_r and k_z, the following decreasing order of thermal conductivity value\nis observed: SI 4H-SiC > n-type 4H-SiC > SI 6H-SiC. This work serves as an\nimportant benchmark for understanding thermal transport in WBG semiconductors.",
        "positive": "Full Potential Multiple Scattering for X-ray Spectroscopies: We present a Full Potential Multiple Scattering (FP-MS) scheme for the\ninterpretation of several X-ray spectroscopies that is a straightforward\ngeneralization of the more conventional Muffin-Tin (MT) version. Like this\nlatter, it preserves the intuitive description of the physical process under\nconsideration and overcomes some of the limitations of the existing FP-MS\ncodes. It hinges on a fast and efficient method for solving the single cell\nscattering problem that avoids the convergence drawbacks of the angular\nmomentum (AM) expansion of the cell shape function and relies on an alternative\nderivation of the multiple scattering equations (MSE) that allows us to work\nreliably with only one truncation parameter, {\\it i.e.} the number of local\nbasis functions in the expansion of the global scattering function determined\nby the classical relation $l_{\\rm max} \\sim k R$."
    },
    {
        "anchor": "Molecular dynamics simulation for heat transport in thin diamond\n  nanowires: The phonon thermal conductivity in diamond nanowires (DNW) is studied by\nmolecular dynamics simulation. It is found that the thermal conductivity in\nnarrower DNW is lower and does not show obvious temperature dependence; a very\nsmall value (about 2.0 W/m/K) of thermal conductivity is observed in\nultra-narrow DNW, which may be of potential applications in thermoelectric\ndevices. These two phenomena are probably due to the dominant surface effect\nand phonon confinement effect in narrow DNW. Our simulation reveals a high\nanisotropy in the heat transport of DNW. Specifically, the thermal conductivity\nin DNW along [110] growth direction is about five times larger than that of\n[100] and [111] growth directions. The anisotropy is believed to root in the\nanisotropic group velocity for acoustic phonon modes in DNW along three\ndifferent growth directions.",
        "positive": "Magnetic Structure and Spin Waves in the Kagom\u00e9 Jarosite compound\n  ${\\bf KFe_3(SO_4)_2(OH)_6}$: We present a detailed study of the magnetic structure and spin waves in the\nFe jarosite compound ${\\rm KFe_3(SO_4)_2(OH)_6}$ for the most general\nHamiltonian involving one- and two-spin interactions which are allowed by\nsymmetry. We compare the calculated spin-wave spectrum with the recent neutron\nscattering data of Matan {\\it et al.} for various model Hamiltonians which\ninclude, in addition to isotropic Heisenberg exchange interactions between\nnearest ($J_1$) and next-nearest ($J_2$) neighbors, single ion anisotropy and\nDzyaloshinskii-Moriya (DM) interactions. We concluded that DM interactions are\nthe dominant anisotropic interaction, which not only fits all the splittings in\nthe spin-wave spectrum but also reproduces the small canting of the spins out\nof the Kagom\\'e plane. A brief discussion of how representation theory\nrestricts the allowed magnetic structure is also given."
    },
    {
        "anchor": "Real-time Stress Measurements in Germanium Thin Film Electrodes during\n  Electrochemical Lithiation/delithiation Cycling: An in situ study of stress evolution and mechanical behavior of germanium as\na lithium-ion battery electrode material is presented. Thin films of germanium\nare cycled in a half-cell configuration with lithium metal foil as\ncounter/reference electrode, with 1M LiPF6 in ethylene carbonate, diethyl\ncarbonate, dimethyl carbonate solution (1:1:1, wt. %) as electrolyte. Real-time\nstress evolution in the germanium thin-film electrodes during electrochemical\nlithiation/delithiation is measured by monitoring the substrate curvature using\nthe multi-beam optical sensing method. Upon lithiation a-Ge undergoes extensive\nplastic deformation, with a peak compressive stress reaching as high as -0.76\n+/- 0.05 GPa (mean +/- standard deviation). The compressive stress decreases\nwith lithium concentration reaching a value of approximately -0.3 GPa at the\nend of lithiation. Upon delithiation the stress quickly became tensile and\nfollows a trend that mirrors the behavior on compressive side; the average peak\ntensile stress of the lithiated Ge samples was approximately 0.83 GPa. The peak\ntensile stress data along with the SEM analysis was used to estimate a lower\nbound fracture resistance of lithiated Ge, which is approximately 5.3 J/m^2. It\nwas also observed that the lithiated Ge is rate sensitive, i.e., stress depends\non how fast or slow the charging is carried out.",
        "positive": "Proposal for a three-dimensional magnetic measurement method with\n  nanometer-scale depth resolution: We propose a magnetic measurement method based on combining depth sectioning\nand electron magnetic circular dichroism in scanning transmission electron\nmicroscopy. Electron vortex beams with large convergence angles, as those\nachievable in current state-of-the-art aberration correctors, could produce\natomic lateral resolution and depth resolution below 2~nm."
    },
    {
        "anchor": "Microscopic origin of magnetization reversal in exchange-coupled\n  ferro-/ferrimagnetic bilayers: In this study, the magnetic reversal process of exchange-coupled bilayer\nsystems, consisting of a ferrimagnetic TbFeCo alloy layer and a ferromagnetic\n[Co/Ni/Pt]N multilayer, was investigated. In particular, minor loop studies,\nprobing solely the reversal characteristics of the softer ferromagnetic layer,\nreveal two distinct reversal mechanisms, which depend strongly on the thickness\nof the ferromagnetic layer. For thick layers, irreversible switching of the\nmacroscopic minor loop is observed. The underlying microscopic origin of this\nreversal process was studied in detail by high-resolution magnetic force\nmicroscopy, showing that the reversal is triggered by in-plane domain walls\npropagating through the ferromagnetic layer. In contrast, thin ferromagnetic\nlayers show a hysteresis-free reversal, which is nucleation-dominated due to\ngrain-to-grain variations in magnetic anisotropy of the Co/Ni/Pt multilayer and\nan inhomogeneous exchange coupling with the magnetically hard TbFeCo layer, as\nconfirmed by micromagnetic simulations.",
        "positive": "Soft-Elasticity Optimises Dissipation in 3D-Printed Liquid Crystal\n  Elastomers: Soft-elasticity in monodomain liquid crystal elastomers (LCEs) is promising\nfor impact-absorbing applications where strain energy is ideally absorbed at\nconstant stress. Conventionally, compressive and impact studies on LCEs have\nnot been performed given the notorious difficulty synthesizing sufficiently\nlarge monodomain devices. Here we demonstrate 3D printing bulk ($>cm^3$)\nmonodomain LCE devices using direct ink writing and study their compressive\nsoft-elasticity over 8 decades of strain rate. At quasi-static rates, the\nmonodomain soft-elastic LCE dissipated 45% of strain energy while comparator\nmaterials dissipated less than 20%. At strain rates up to $3000~s^{-1}$, our\nsoft-elastic monodomain LCE consistently performed closest to an ideal-impact\nabsorber. Drop testing reveals soft-elasticity as a likely mechanism for\neffectively reducing the severity of impacts -- with soft elastic LCEs offering\na Gadd Severity Index 40% lower than a comparable isotropic elastomer. Lastly,\nwe demonstrate tailoring deformation and buckling behavior in monodomain LCEs\nvia the printed director orientation."
    },
    {
        "anchor": "Computational Study of Defect variant Perovskites A2BX6 for Photovoltaic\n  Applications: A comprehensive study of the structural, electronic, and optical properties\nof lead-free perovskites has been carried out by means of first principles\nmethod based on DFT. The calculations are performed for the compound of the\ntype A2BX6 with A=Rb, and Cs; B=Sn, Pd, and Pt; and X=Cl, Br, and I. The\ncalculated structural parameters (lattice constants and bond lengths) agree\nwell with the experiments. The computed band gap reveals a semiconducting\nprofile for all these compounds showing a decreasing trend of the band gap\nenergy by changing the halide ions consecutively from Cl to Br and Br to I.\nHowever, for variation in the B-site cation, the band gap increases by changing\nthe cation from Pd to Pt via Sn. The most likely compounds, Rb2PdBr6 and\nCs2PtI6, exhibit a band gap within the optimal range of 0.9-1.6 eV for\nsingle-junction photovoltaic applications. The optical properties in terms of\nthe optimal value of the dielectric constant, optical conductivity, and\nabsorption coefficient are also investigated upto the photon energy of 10 eV.\nOur results indicate that upon changing the halogen ions (Cl by Br and Br by I)\nthe optical properties altered significantly. Maximum dielectric constants and\nhigh optical absorption are found for Rb2PdI6 and Cs2PtI6. The unique\noptoelectronic properties such as ideal band gap, high dielectric constants,\nand optimum absorption of A2BX6 perovskites could be efficiently utilized in\ndesigning high performance single and multi-junction perovskite solar cells.",
        "positive": "Conductivity and Dissociation in Metallic Hydrogen: Implications for\n  Planetary Interiors: Liquid metallic hydrogen (LMH) was recently produced under static compression\nand high temperatures in bench-top experiments. Here, we report a study of the\noptical reflectance of LMH in the pressure region of 1.4-1.7 Mbar and use the\nDrude free-electron model to determine its optical conductivity. We find static\nelectrical conductivity of metallic hydrogen to be 11,000-15,000 S/cm. A\nsubstantial dissociation fraction is required to best fit the energy dependence\nof the observed reflectance. LMH at our experimental conditions is largely\natomic and degenerate, not primarily molecular. We determine a plasma frequency\nand the optical conductivity. Properties are used to analyze planetary\nstructure of hydrogen rich planets such as Jupiter."
    },
    {
        "anchor": "Novel materials in the Materials Cloud 2D database: Two-dimensional (2D) materials are among the most promising candidates for\nbeyond-silicon electronic, optoelectronic and quantum computing applications.\nRecently, their recognized importance sparked a push to discover and\ncharacterize novel 2D materials. Within a few years, the number of\nexperimentally exfoliated or synthesized 2D materials went from a couple of\ndozens to more than a hundred, with the number of theoretically predicted\ncompounds reaching a few thousands. In 2018 we first contributed to this effort\nwith the identification of 1825 compounds that are either easily (1036) or\npotentially (789) exfoliable from experimentally known 3D compounds. Here, we\nreport on a major expansion of this 2D portfolio thanks to the extension of the\nscreening protocol to an additional experimental database (MPDS) as well as to\nthe updated versions of the two databases (ICSD and COD) used in our previous\nwork. This expansion has led to the discovery of additional 1252 unique\nmonolayers, bringing the total to 3077 compounds and, notably, almost doubling\nthe number of easily exfoliable materials (2004). Moreover, we optimized the\nstructural properties of all these monolayers and explored their electronic\nstructure with a particular emphasis on those rare large-bandgap 2D materials\nthat could be precious to isolate 2D field effect transistors channels.\nFinally, for each material containing up to 6 atoms per unit cell, we\nidentified the best candidates to form commensurate heterostructures, balancing\nrequirements on the supercells size and minimal strain.",
        "positive": "Structure and magnetism of self-organized Ge(1-x)Mn(x) nano-columns: We report on the structural and magnetic properties of thin Ge(1-x)Mn(x)films\ngrown by molecular beam epitaxy (MBE) on Ge(001) substrates at temperatures\n(Tg) ranging from 80deg C to 200deg C, with average Mn contents between 1 % and\n11 %. Their crystalline structure, morphology and composition have been\ninvestigated by transmission electron microscopy (TEM), electron energy loss\nspectroscopy and x-ray diffraction. In the whole range of growth temperatures\nand Mn concentrations, we observed the formation of manganese rich\nnanostructures embedded in a nearly pure germanium matrix. Growth temperature\nmostly determines the structural properties of Mn-rich nanostructures. For low\ngrowth temperatures (below 120deg C), we evidenced a two-dimensional spinodal\ndecomposition resulting in the formation of vertical one-dimensional\nnanostructures (nanocolumns). Moreover we show in this paper the influence of\ngrowth parameters (Tg and Mn content) on this decomposition i.e. on nanocolumns\nsize and density. For temperatures higher than 180deg C, we observed the\nformation of Ge3Mn5 clusters. For intermediate growth temperatures nanocolumns\nand nanoclusters coexist. Combining high resolution TEM and superconducting\nquantum interference device magnetometry, we could evidence at least four\ndifferent magnetic phases in Ge(1-x)Mn(x) films: (i) paramagnetic diluted Mn\natoms in the germanium matrix, (ii) superparamagnetic and ferromagnetic low-Tc\nnanocolumns (120 K < Tc < 170 K), (iii) high-Tc nanocolumns (Tc> 400 K) and\n(iv) Ge3Mn5 clusters."
    },
    {
        "anchor": "A kinetic description of Vanadium carbide coating formed by the plasma\n  electrolytic method: The old creation method of this coating is using salt bath for an approximate\ntime of 6 to 10 hours, which means wasting a lot of time and energy while the\nformation of this coating with the plasma electrolytic method just takes about\n15 minutes and it can increase the efficiency strongly on an industrial scale.\nIn this research, the process has been applied on the samples of 1.2436 steel\nin different periods. Then, thickness of the coating layers has been measured\nby using SEM images and thermodynamic data of Vanadium carbide formation. These\nresults have been expanded to access and present a confirmed model to predict\nthe thickness of this diffusion-based coating as a function of time and\nreaction temperature. The proven model can be used to demonstrate and prove the\nkinetic advantage of this method and also find the optimal value of applying\ntime and temperature.",
        "positive": "Controlling the phase locking of unstable magnetic bits for ultra-low\n  power computation: When fabricating magnetic memories, one of the main challenges is to maintain\nthe bit stability while downscaling. Indeed, for magnetic volumes of a few\nthousand nm3, the energy barrier between magnetic configurations becomes\ncomparable to the thermal energy at room temperature. Then, switches of the\nmagnetization spontaneously occur. These volatile, superparamagnetic\nnanomagnets are generally considered useless. But what if we could use them as\nlow power computational building blocks? Remarkably, they can oscillate without\nthe need of any external dc drive, and despite their stochastic nature, they\ncan beat in unison with an external periodic signal. Here we show that the\nphase locking of superparamagnetic tunnel junctions can be induced and\nsuppressed by electrical noise injection. We develop a comprehensive model\ngiving the conditions for synchronization, and predict that it can be achieved\nwith a total energy cost lower than 10-^13 J. Our results open the path to\nultra-low power computation based on the controlled synchronization of\noscillators."
    },
    {
        "anchor": "Angle-resolved photoemission and first-principles electronic structure\n  of single-crystalline $\u03b1$-uranium (001): Continuing the photoemission study begun with the work of Opeil et al. [Phys.\nRev. B \\textbf{73}, 165109 (2006)], in this paper we report results of an\nangle-resolved photoemission spectroscopy (ARPES) study performed on a\nhigh-quality single-crystal $\\alpha$-uranium at 173 K. The absence of\nsurface-reconstruction effects is verified using X-ray Laue and low-energy\nelectron diffraction (LEED) patterns. We compare the ARPES intensity map with\nfirst-principles band structure calculations using a generalized gradient\napproximation (GGA) and we find good correlations with the calculated\ndispersion of the electronic bands.",
        "positive": "Ab initio Modelling of the Early Stages of Precipitation in Al-6000\n  Alloys: Age hardening induced by the formation of (semi)-coherent precipitate phases\nis crucial for the processing and final properties of the widely used Al-6000\nalloys. Early stages of precipitation are particularly important from the\nfundamental and technological side, but are still far from being fully\nunderstood. Here, an analysis of the energetics of nanometric precipitates of\nthe meta-stable $\\beta''$ phases is performed, identifying the bulk, elastic\nstrain and interface energies that contribute to the stability of a nucleating\ncluster. Results show that needle-shape precipitates are unstable to growth\neven at the smallest size $\\beta''$ formula unit, i.e. there is no energy\nbarrier to growth. The small differences between different compositions points\ntoward the need for the study of possible precipitate/matrix interface\nreconstruction. A classical semi-quantitative nucleation theory approach\nincluding elastic strain energy captures the trends in precipitate energy\nversus size and composition. This validates the use of mesoscale models to\nassess stability and interactions of precipitates. Studies of smaller 3d\nclusters also show stability relative to the solid solution state, indicating\nthat the early stages of precipitation may be diffusion-limited. Overall, these\nresults demonstrate the important interplay among composition-dependent bulk,\ninterface, and elastic strain energies in determining nanoscale precipitate\nstability and growth."
    },
    {
        "anchor": "Nonequilibrium Charge-Density-Wave Order Beyond the Thermal Limit: The interaction of many-body systems with intense light pulses may lead to\nnovel emergent phenomena far from equilibrium. Recent discoveries, such as the\noptical enhancement of the critical temperature in certain superconductors and\nthe photo-stabilization of hidden phases, have turned this field into an\nimportant research frontier. Here, we demonstrate nonthermal\ncharge-density-wave (CDW) order at electronic temperatures far greater than the\nthermodynamic transition temperature. Using time- and angle-resolved\nphotoemission spectroscopy and time-resolved X-ray diffraction, we investigate\nthe electronic and structural order parameters of an ultrafast photoinduced\nCDW-to-metal transition. Tracking the dynamical CDW recovery as a function of\nelectronic temperature reveals a behaviour markedly different from equilibrium,\nwhich we attribute to the suppression of lattice fluctuations in the transient\nnonthermal phonon distribution. A complete description of the system's coherent\nand incoherent order-parameter dynamics is given by a time-dependent\nGinzburg-Landau framework, providing access to the transient potential energy\nsurfaces.",
        "positive": "First-principles calculation of the parameters used by atomistic\n  magnetic simulations: While the ground state of magnetic materials is in general well described on\nthe basis of spin density functional theory (SDFT), the theoretical description\nof finite-temperature and non-equilibrium properties require an extension\nbeyond the standard SDFT. Time-dependent SDFT (TD-SDFT), which give for example\naccess to dynamical properties are computationally very demanding and can\ncurrently be hardly applied to complex solids. Here we focus on the alternative\napproach based on the combination of a parameterized phenomenological spin\nHamiltonian and SDFT-based electronic structure calculations, giving access to\nthe dynamical and finite-temperature properties for example via spin-dynamics\nsimulations using the Landau-Lifshitz-Gilbert (LLG) equation or Monte Carlo\nsimulations. We present an overview on the various methods to calculate the\nparameters of the various phenomenological Hamiltonians with an emphasis on the\nKKR Green function method as one of the most flexible band structure methods\ngiving access to practically all relevant parameters. Concerning these, it is\ncrucial to account for the spin-orbit coupling (SOC) by performing relativistic\nSDFT-based calculations as it plays a key role for magnetic anisotropy and\nchiral exchange interactions represented by the DMI parameters in the spin\nHamiltonian. This concerns also the Gilbert damping parameters characterizing\nmagnetization dissipation in the LLG equation, chiral multispin interaction\nparameters of the extended Heisenberg Hamiltonian, as well as spin-lattice\ninteraction parameters describing the interplay of spin and lattice dynamics\nprocesses, for which an efficient computational scheme has been developed\nrecently by the present authors."
    },
    {
        "anchor": "Mapping electronic states of dual-parallel and symmetric zigzag grain\n  boundaries of graphene on highly oriented pyrolytic graphite: The grain boundaries (GBs) of a graphene surface were extensively studied\nbecause GBs with specific defect configurations result in the formation of new\ncurved structures, which can be treated as new carbon allotropes. We studied\nthe structures and electronic spectra of two periodic GBs in graphene on highly\noriented pyrolytic graphite (HOPG) surfaces using scanning tunneling microscopy\nand spectroscopy (STM/S). Our results demonstrated that a GB consisting of dual\nparallel periodic dislocation cores of pentagonal-heptagonal (5-7) carbon rings\ngives rise to an enhanced localized state at 0.45 eV above the Dirac point in\ngraphene surfaces, which is attributed to van Hove singularities (VHSs).\nMoreover, the energy positions of the localized states are varied between 0.40\nand 0.47 eV depending on the site and eventually decayed to 0.36 eV. The\nvariation of the energy positions is induced by two parallel GBs because of the\nhigher electron density at the GB as a defect center and the lower electron\naway from the GB. Another periodic GB with a symmetric zigzag structural\nfeature induced VHSs at -0.038 and 0.12 eV near the Fermi level. Moreover,\nintervalley scattering was observed on both these GBs. This means that carrier\nconcentration and thus, the conductance around the periodic GBs can be\nsignificantly enhanced by localized density of states. This finding suggests\nthat graphene with a properly embedded ordered GB is promising for improving\nthe performance of graphene-based electronic devices.",
        "positive": "Exchange Bias following Kinetic Arrest: Exchange bias is often observed when anti-ferromagnetic and ferromagnetic\nphases coexist. The coexistence of two competing magnetic phases can persist to\nthe lowest temperatures if the disorder-broadened 1st order transition\nseparating them is interrupted, as is proposed in the kinetic arrest\nphenomenon. The fractions of coexisting phases can, in this phenomenon, be\ntuned by following different cooling protocols. We discuss predicted behaviours\nof exchange bias resulting from the kinetic arrest phenomenon. Specifically,\nfor appropriate values of cycling field Hmax and measuring temperature T0 there\nwill be no exchange bias under cooling in zero field, while it will manifest\nwith increasing cooling field, and then saturate."
    },
    {
        "anchor": "Experimental signature of bandgap opening in bilayer graphene at metal\n  contacts: Bilayer graphene (BLG) possesses a finite bandgap when a potential difference\nis introduced between the two graphene layers. The potential difference is\nknown to be introduced by surface charge transfer. Thus, it is expected that a\nfinite bandgap exists at the metal contacts. The bandgap at the metal-BLG\ninterface can be detected by the superlinear current-voltage characteristics in\nback-gate field-effect transistors, caused by carriers tunneling through the\nbandgap. The superlinearity was higher in the positively gated region,\nattributed to hole doping from the Cr/Au electrodes. The control experiments\nusing single-layer graphene (SLG) did not have a superlinearity, which is\nconsistent with the fact that a sizeable bandgap is not expected at the\nmetal-SLG interface. The opening of a bandgap at the metal-BLG interface is an\nadditional source of electrode-contact resistance.",
        "positive": "Amorphous state of sp$^2$ solid carbon: Two-mode valence electron configuration of carbon atoms lays the foundation\nof the unique two-mode amorphous state of the monoatomic carbon solid. From the\nfundamentals of solid-state physics, sp$^3$ and sp$^2$ amorphous carbons are\ntwo different amorphous species characterized by conceptually different\nshort-range orders, namely, groups of tetrahedrally bonded sp3 configured atoms\nand size-restricted sp$^2$ graphene domains framed with heteroatom necklaces.\nMolecular character of sp$^2$ amorphics is coherent with the reaction mechanism\nof the solid amorphicity in due course of the forced fragmentation."
    },
    {
        "anchor": "Tuning of magnetic frustration in $S=1/2$ Kagom\u00e9 lattices\n  {[Cu$_{3}$(CO$_{3}$)$_{2}$$(bpe)_{3}$](ClO$_{4}$)$_2$}$_{n}$ and\n  {[Cu$_{3}$(CO$_{3}$)$_{2}$$(bpy)_{3}$](ClO$_{4}$)$_2$}$_{n}$ through rigid\n  and flexible ligands: Single crystalline and polycrystalline samples of $S=1/2$ Kagom\\'{e} lattices\n{[Cu$_{3}$(CO$_{3}$)$_{2}$$(bpe)_{3}$](ClO$_{4}$)$_2$}$_{n}$ and\n{[Cu$_{3}$(CO$_{3}$)$_{2}$$(bpy)_{3}$](ClO$_{4}$)$_2$}$_{n}$, respectively were\nsynthesized. Their structural and magnetic properties were characterized by\nmeans of x-ray diffraction and magnetization measurements. Both compounds\ncrystalize in a hexagonal structure (space group $P-6$) consisting of CuO$_4$\nKagom\\'{e} layers in the $ab$-plane but linked along $c$ direction through\neither rigid $bpy$ or flexible $bpe$ ligands to form 3D frame works. Magnetic\nmeasurements reveal that both the compounds undergo ferromagnetic ordering\n($T_{\\rm C}$) at low temperatures and the $T_{\\rm C}$ and the extent of\nfrustration could be tuned by changing the nature of the pillar ligands.\n{[Cu$_{3}$(CO$_{3}$)$_{2}$$(bpe)_{3}$](ClO$_{4}$)$_2$}$_{n}$ which is made up\nof flexible $bpe$ ligands has a $T_{\\rm C}$ of 5.7 K and a Curie-Weiss\ntemperature ($\\theta_{\\rm CW}$) of -39.7 K giving rise to a frustration\nparameter of $\\frac{|\\theta_{\\rm CW}|}{T_{\\rm C}} \\simeq$ 6.96. But the\nreplacement of $bpe$ by a more rigid and electronically delocalized $bpy$\nligand leads to an enhanced $T_{\\rm C} \\simeq$ 9.3 K and a reduced frustration\nparameter of $\\frac{|\\theta_{\\rm CW}|}{T_{\\rm C}} \\simeq$ 3.54.",
        "positive": "Density functional theory study of the electronic structure of fluorite\n  Cu$_{2}$Se: We have investigated the electronic structure of fluorite Cu$_{2}$Se using\ndensity functional theory calculations within the LDA, PBE and AM05\napproximations as well as with the non-local hybrid PBE0 and HSE\napproximations. Our results show that Cu$_{2}$Se is a zero gap semiconductor\nwhen using either a local or semi-local density functional approximation while\nthere exists a gap when using the PBE0 functional. For the HSE approximation,\nwe find that the presence of a gap depends on the range separation for the\nnon-local exchange within the HSE approximation. For the occupied states we\nfind that the LDA, PBE, AM05, PBE0 and HSE agrees when regarding the overall\nstructure, however, the hybrid functionals are shifted towards lower energy\nvalues compared to the LDA, PBE and AM05. The valence bands obtained using the\nhybrid functionals are in good agreement with experimental valence band\nspectra. We also find that the PBE, PBE0 and HSE approximations give similar\nresults regarding bulk properties, such as lattice constants and bulk modulus.\nIn addition, we have investigated the localization of the Cu d-states and its\neffect on the band gap in the material using the LDA+U approach. We find that a\ngap is opened up by increasing the $U$, however, the $U$ values required for a\ngap opening is unrealistically high."
    },
    {
        "anchor": "Solid-State Dewetting and Island Morphologies in Strongly Anisotropic\n  Materials: We propose a sharp-interface continuum model based on a thermodynamic\nvariational approach to investigate the strong anisotropic effect on\nsolid-state dewetting including contact line dynamics. For sufficiently strong\nsurface energy anisotropy, we show that multiple equilibrium shapes may appear\nthat can not be described by the widely employed Winterbottom construction,\ni.e., the modified Wulff construction for an island on a substrate. We repair\nthe Winterbottom construction to include multiple equilibrium shapes and employ\nour evolution model to demonstrate that all such shapes are dynamically\naccessible.",
        "positive": "Invoking forbidden modes in SnO_2 nanoparticles using tip enhanced Raman\n  spectroscopy: Raman forbidden modes and surface defect related Raman features in SnO_2\nnanostructures carry information about disorder and surface defects which\nstrongly influence important technological applications like catalysis and\nsensing. Due to the weak intensities of these peaks, it is difficult to\nidentify these features by using conventional Raman spectroscopy. Tip enhanced\nRaman spectroscopy (TERS) studies conducted on SnO_2 nanoparticles (NPs) of\nsize 4 and 25 nm have offered significant insights of prevalent defects and\ndisorders. Along with one order enhancement in symmetry allowed Raman modes,\nnew peaks related to disorder and surface defects of SnO_2 NPs were found with\nsignificant intensity. Temperature dependent Raman studies were also carried\nout for these NPs and correlated with the TERS spectra. For quasi-quantum dot\nsized 4 nm NPs, the TERS study was found to be the best technique to probe the\nfinite size related Raman forbidden modes."
    },
    {
        "anchor": "The band structure of MgB$_{2}$ with different lattice constants: We report a detailed study of the electronic structure of the MgB$_{2}$ with\ndifferent lattice constants by using the full-potential linearized augmented\nplane wave(FPLAPW) method. It is found that the lattice parameters have great\neffect on the $\\sigma$ band of Boron. Our results indicate that increasing\nlattice constant along the {\\it c} axis will increase the density of\nstates(DOS) at the Fermi level, making the $\\sigma$ band upward shift, and\nincreasing hole number in the $\\sigma$ band. So, the superconducting transition\ntemperature T$_{c}$ will be raised correspondingly. Changing the lattice\nconstant along {\\it a} axis has an opposite effect to that of along {\\it c}\naxis. Our result is in agreement with experiment. A possible way of searching\nfor higher T$_{c}$ superconductor has been indicated, i.e., making MgB$_{2}$ to\nhave longer {\\it c} axis and shorter {\\it a, b} axis by doping.",
        "positive": "Theoretical study of structure and magnetism of Ga$_{1-x}$V$_x$Sb\n  compounds for spintronic applications: In this paper, the structural, electronic and magnetic properties of\nZinc-blende Ga1-xVxSb compounds, with x from dilute doping situation to extreme\ndoping limiting, were systematically investigated by first-principles\ncalculations. V atoms prefer to substitute the Ga atoms and the formation\nenergy is lower in Sb-rich than Ga-rich growth condition. Meantime, the SbGa\nantisite defects can effectively decrease the energy barrier of substitution\nprocess, from 0.85 eV to 0.53 eV. The diffusion of V atom in GaSb lattice is\nthrough meta-stable interstitial sites with an energy barrier of 0.6 eV. At a\nlow V concentration x = 0.0625, V atoms prefer a homogeneous distribution and\nan antiferromagnetic coupling among them. However, starting from x = 0.5, the\nmagnetic coupling among V atoms changes to be ferromagnetic, due to enhanced\nsuperexchange interaction between eg and t2g states of neighbouring V atoms. At\nthe extreme limiting of x = 1.00, we found that Zinc-blende VSb as well as its\nanalogs VAs and VP are intrinsic ferromagneitc semiconductors, with a large\nchange of light absorption at the curie temperature. These results indicate\nthat Ga1-xVxSb compounds can provide a platform to design the new electronic,\nspintronic and optoelectronic devices."
    },
    {
        "anchor": "Seeds of imperfection rule the mesocrystalline disorder in natural\n  anhydrite single crystals: In recent years, we have come to appreciate the astounding intricacy of the\nformation process of minerals from ions in aqueous solutions. In this context,\na number of studies have revealed that nucleation in the calcium sulfate system\nis non-classical, involving the aggregation and reorganization of nanosized\nprenucleation particles. In a recent work we have shown that this\nparticle-mediated nucleation pathway is actually imprinted in the resultant\nsingle micron-sized CaSO4 crystals. This property of CaSO4 minerals provides us\nwith an unique opportunity to search for evidence of non-classical nucleation\npathways in geological environments. In particular, we focused on the\nquintessential single crystals of anhydrite extracted from the Naica mine in\nMexico. We elucidated the growth history from this mineral sample by mapping\ngrowth defects at different length scales. Based on these data we argue that\nthe nano-scale misalignment of the structural sub-units observed in the initial\ncalcium sulfate crystal seed propagate through different length-scales both in\nmorphological, as well as strictly crystallographic aspects, eventually causing\nthe formation of large mesostructured single crystals of anhydrite. Hence, the\nnanoparticle mediated nucleation mechanism introduces a 'seed of imperfection',\nwhich leads to a macroscopic single crystal, in which its fragments do not fit\ntogether at different length-scales in a self-similar manner. Consequently,\nanisotropic voids of various sizes are formed with very well-defined\nwalls/edges. But, at the same time the material retains its essential single\ncrystal nature. These findings shed new light on the longstanding concept of\ncrystal structure.",
        "positive": "Nanobatteries in redox-based resistive switches require extension of\n  memristor theory: Redox-based nanoionic resistive memory cells (ReRAMs) are one of the most\npromising emerging nano-devices for future information technology with\napplications for memory, logic and neuromorphic computing. Recently, the\nserendipitous discovery of the link between ReRAMs and memristors and\nmemristive devices has further intensified the research in this field. Here we\nshow on both a theoretical and an experimental level that nanoionic-type\nmemristive elements are inherently controlled by non-equilibrium states\nresulting in a nanobattery. As a result the memristor theory must be extended\nto fit the observed non zerocrossing I-V characteristics. The initial\nelectromotive force of the nanobattery depends on the chemistry and the\ntransport properties of the materials system but can also be introduced during\nReRAM cell operations. The emf has a strong impact on the dynamic behaviour of\nnanoscale memories, and thus, its control is one of the key factors for future\ndevice development and accurate modelling."
    },
    {
        "anchor": "Genomic Materials Design: CALculation of PHAse Dynamics: The CALPHAD system of fundamental phase-level databases, now known as the\nMaterials Genome, has enabled a mature technology of computational materials\ndesign and qualification that has already met the acceleration goals of the\nnational Materials Genome Initiative. As first commercialized by QuesTek\nInnovations, the methodology combines efficient genomic-level parametric design\nof new material composition and process specifications with multidisciplinary\nsimulation-based forecasting of manufacturing variation, integrating efficient\nuncertainty management. Recent projects demonstrated under the\nmulti-institutional CHiMaD Design Center notably include novel alloys designed\nspecifically for the new technology of additive manufacturing. With the proven\nsuccess of the CALPHAD-based Materials Genome technology, current university\nresearch emphasizes new methodologies for affordable accelerated expansion of\nmore accurate CALPHAD databases. Rapid adoption of these new capabilities by US\napex corporations has compressed the materials design and development cycle to\nunder 2 years, enabling a new \"materials concurrency\" integrated into a new\nlevel of concurrent engineering supporting an unprecedented level of\nmanufacturing innovation.",
        "positive": "Theory of ultrathin films at metal-ceramic interfaces: A theoretical model for understanding the formation of interfacial thin films\nis presented, which combines density functional theory calculations for\ninterface energies with thermodynamic modeling techniques for multicomponent\nbulk systems. The theory is applied to thin film formation in VC-doped WC-Co\ncemented carbides. It is predicted that ultrathin VC films may exist in WC/Co\ninterfaces at the high temperature sintering conditions where most of the WC\ngrain growth occurs, which provides an explanation of the grain growth\ninhibiting effect of VC additions in the WC-Co system."
    },
    {
        "anchor": "Silicon solar cells efficiency analysis. Doping type and level\n  optimization: The theoretical analysis of photovoltaic conversion efficiency of highly\neffective silicon solar cells (SC) is performed for n-type and p-type bases.\nThe case is considered when the Shockley-Read-Hall recombination in the silicon\nbulk is determined by the deep level of Fe. It is shown that due to the\nasymmetry of the recombination parameters of this level the photovoltaic\nconversion efficiency is increasing in the SC with the n-type base and\ndecreasing in the SC with the p-type base with the increase in doping. Two\napproximations for the band-to-band Auger recombination lifetime dependence on\nthe base doping level are considered when performing the analysis. The\nexperimental results are presented for the key characteristics of the solar\ncells based on $\\alpha-Si:H-n-Si$ heterojunctions with intrinsic thin layer\n(HIT). A comparison between the experimental and calculated values of the HIT\ncells characteristics is made. The surface recombination velocity and series\nresistance are determined from it with a complete coincidence of the\nexperimental and calculated SC parameters' values.",
        "positive": "Transient grating spectroscopy of thermal diffusivity degradation in\n  deuterium implanted tungsten: Using transient grating spectroscopy, we measure thermal diffusivity and\nsurface acoustic wave speed in tungsten exposed to different fluences of\ndeuterium plasma. Scanning electron microscopy (SEM) shows the formation of\nsurface blisters that have similar morphology for all fluences. A significant\nreduction in thermal diffusivity and surface acoustic wave speed occurs as a\nresult of plasma exposure. A saturation of the thermal diffusivity reduction\nwith fluence is seen. Deuterium ion flux density appears play a more important\nrole in the thermal diffusivity reduction than the fluence. These results have\nimportant implications for plasma facing components in future fusion reactors."
    },
    {
        "anchor": "Robust Training of Machine Learning Interatomic Potentials with\n  Dimensionality Reduction and Stratified Sampling: Machine learning interatomic potentials (MLIPs) enable the accurate\nsimulation of materials at larger sizes and time scales, and play increasingly\nimportant roles in the computational understanding and design of materials.\nHowever, MLIPs are only as accurate and robust as the data they are trained on.\nIn this work, we present DImensionality-Reduced Encoded Clusters with\nsTratified (DIRECT) sampling as an approach to select a robust training set of\nstructures from a large and complex configuration space. By applying DIRECT\nsampling on the Materials Project relaxation trajectories dataset with over one\nmillion structures and 89 elements, we develop an improved materials 3-body\ngraph network (M3GNet) universal potential that extrapolate more reliably to\nunseen structures. We further show that molecular dynamics (MD) simulations\nwith universal potentials such as M3GNet can be used in place of expensive\n\\textit{ab initio} MD to rapidly create a large configuration space for target\nmaterials systems. Combined with DIRECT sampling, we develop a highly reliable\nmoment tensor potential for Ti-H system without the need for iterative\noptimization. This work paves the way towards robust high throughput\ndevelopment of MLIPs across any compositional complexity.",
        "positive": "Electrical and magnetic transport properties of Fe3O4 thin films on GaAs\n  (100) substrate: Thin films of magnetite (Fe3O4) are grown on single crystal GaAs (100)\nsubstrate by pulsed laser deposition. X ray diffraction (XRD) result shows the\n(111) preferred orientation of the Fe3O4 film and x-ray photoelectron\nspectroscopy confirm the presence of single phase Fe3O4 in the film. The\nelectrical transport property of the film shows the characteristic Verwey\ntransition at 122 K and below 110 K, the transport follows variable range\nhopping type conduction mechanism. The film shows room temperature\nmagnetization hysteresis loop suggesting the ferrimagnetic behavior of the film\nwith saturation magnetization value close to 470 emu/cc."
    },
    {
        "anchor": "Error Cancellation in Diffusion Monte Carlo Calculations of Surface\n  Chemistry: Diffusion Monte Carlo (DMC) is being recognized as a higher-accuracy, albeit\nmore computationally expensive, alternative to Density Functional Theory (DFT)\nfor energy predictions of catalytic systems. A major computational bottleneck\nin the use of DMC for catalysis is the need to perform finite-size\nextrapolations by simulating increasingly large periodic cells (supercells) to\neliminate many-body finite-size effects and obtain energies in the\nthermodynamic limit. Here, we show that this computational cost can be\nsignificantly reduced by leveraging the cancellation of many-body finite-size\nerrors that accompanies the evaluation of energy differences when calculating\nquantities like binding energies and mapping potential energy surfaces. We test\nthe error cancellation and convergence in two well-known adsorbate/slab\nsystems, H2O/LiH(001) and CO/Pt(111). Based on this, we identify strategies for\nobtaining binding energies in the thermodynamic limit that optimize error\ncancellation to balance accuracy and computational efficiency. We then predict\nthe correct order of adsorption site preference on CO/Pt(111), a challenging\nproblem for DFT. Our accurate, inexpensive DMC calculations recover the top >\nbridge > hollow site order, in agreement with experimental observations. We\nproceed to map the potential energy surface of CO hopping between Pt(111)\nadsorption sites. This reveals the existence of an L-shaped top-bridge-hollow\ndiffusion trajectory characterized by energy barriers that provide an\nadditional kinetic justification for experimental observations of CO/Pt(111)\nadsorption. Overall, this work demonstrates that it is routinely possible to\nachieve order-of-magnitude speedups and memory savings in DMC calculations by\ntaking advantage of error cancellation in the calculation of energy differences\nthat are ubiquitous in heterogeneous catalysis and surface chemistry more\nbroadly.",
        "positive": "Orbital-free DFT study of the energetics of vacancy clustering and\n  prismatic dislocation loop nucleation in aluminum: In the present work, we conduct large-scale orbital-free DFT calculations to\nstudy the energetics of vacancy clustering in aluminum from electronic\nstructure calculations. The simulation domains considered in this study are as\nlarge as those containing a million atoms to accurately account for both the\nelectronic structure and long-ranged elastic fields. Our results indicate that\nvacancy clustering is an energetically favorable mechanisms with positive\nbinding energies for a range of vacancy clusters considered in the present\nstudy. In particular, the $19$ vacancy hexagonal cluster lying in $\\{111\\}$\nplane has a very large binding energy with the relaxed atomic structure\nrepresentative of a prismatic dislocation loop. This suggests that vacancy\nprismatic loops as small as those formed from 19 vacancies are stable, thus\nproviding insights into the nucleation sizes of these defects in aluminum."
    },
    {
        "anchor": "Combined Experimental and Theoretical Studies on Iodine Capture of\n  Zr-based Metal-Organic Frameworks: Effect of N-functionalization and\n  Adsorption Mechanism: The potential leakage of nuclear waste, especially radioiodine, is a major\nsafety concerning issue around the world. To remove radioiodine from nuclear\nwaste efficiently, there is an urgent demand for adsorbents that possess both\nhigh stability and strong adsorption affinity for environmental remediation.\nHerein, two Zr-based metal-organic frameworks (Zr-MOFs) and their\nN-functionalized analogues have been synthesized and researched for iodine\nadsorption in both vapours and solutions. It was found that Zr-MOFs with\nN-enriched ligands (e.g., pyridine and amino) exhibited the faster iodine\nadsorption rate and the higher iodine uptake amount (e.g., reaching adsorption\nequilibrium within 4 hours with the removal rate of above 85% for iodine\nsolution adsorption) than their unfunctionalized counterparts (UiO-66 and\nUiO-67). The critical role played by N-enriched groups in enhancing iodine\nadsorption has been revealed through versatile model fittings, X-ray\nphotoelectron spectroscopy (XPS) and Raman spectroscopy characterizations, as\nwell as density functional theory (DFT) calculations. Compared to those in\namino-group, the N-atoms in pyridine-groups showed a deeper affinity towards\niodine molecules. Remarkably, the N-enriched UiOs adsorbents also exhibited\ngood recyclability, especially UiO-66-PYDC and UiO-67-NH2 could maintain the\nremoval efficiency of 89.05% and 85.49% after four adsorption-desorption\nrecycling tests. With the strong iodine uptake affinity and outstanding\nregeneration performance, this work has systematically investigated the impact\nof N-functionalization on the enhanced performance for iodine capture by using\nthe N-enriched UiO MOFs as promising adsorbents, providing an insightful\nguideline into the physical chemistry of adsorption mechanism behind the\nradioiodine capture.",
        "positive": "Superdiffusive, heterogeneous, and collective particle motion near the\n  jamming transition in athermal disordered materials: We use computer simulations to study the microscopic dynamics of an athermal\nassembly of soft particles near the fluid-to-solid, jamming transition.\nBorrowing tools developed to study dynamic heterogeneity near glass\ntransitions, we discover a number of original signatures of the jamming\ntransition at the particle scale. We observe superdiffusive, spatially\nheterogeneous, and collective particle motion over a characteristic scale which\ndisplays a surprising non-monotonic behavior across the transition. In the\nsolid phase, the dynamics is an intermittent succession of elastic deformations\nand plastic relaxations, which are both characterized by scale-free spatial\ncorrelations and system size dependent dynamic susceptibilities. Our results\nshow that dynamic heterogeneities in dense athermal systems and glass-formers\nare very different, and shed light on recent experimental reports of\n`anomalous' dynamical behavior near the jamming transition of granular and\ncolloidal assemblies."
    },
    {
        "anchor": "A New Formulation of Coupling and Sliding Motions of Grain Boundaries\n  Based on Dislocation Structure: A continuum model of the two dimensional low angle grain boundary motion and\nthe dislocation structure evolution on the grain boundaries has been developed\nin Ref. [48]. The model is based on the motion and reaction of the constituent\ndislocations of the grain boundaries. The long-range elastic interaction\nbetween dislocations is included in the continuum model, and it maintains a\nstable dislocation structure described by the Frank's formula for grain\nboundaries. In this paper, we develop a new continuum model for the coupling\nand sliding motions of grain boundaries that avoids the time-consuming\ncalculation of the long-range elastic interaction. In this model, the\nlong-range elastic interaction is replaced by a constraint of the Frank's\nformula. The constrained evolution problem in our new continuum model is\nfurther solved by using the projection method. Effects of the coupling and\nsliding motions in our new continuum model and relationship with the classical\nmotion by curvature model are discussed. The continuum model is validated by\ncomparisons with discrete dislocation dynamics model and the early continuum\nmodel [48] in which the long-range dislocation interaction is explicitly\ncalculated.",
        "positive": "Growth of Nanosize and Colloid Particles by Controlled Addition of\n  Singlets: We outline a theoretical framework for estimating the evolution of the\nparticle size distribution in colloid and nanoparticle synthesis, when the\nprimary growth mode is by externally controlled addition of singlet building\nblocks. The master equations, analyzed in the leading \"non-diffusive\" expansion\napproximation, are reduced to a set of easily numerically programmable\nrelations that yield information on the time evolution of the particle size\ndistribution."
    },
    {
        "anchor": "Ultrafast electronic and lattice dynamics in laser-excited crystalline\n  bismuth: Femtosecond spectroscopy is applied to study transient electronic and lattice\nprocesses in bismuth. Components with relaxation times of 1 ps, 7 ps and ~ 1 ns\nare detected in the photoinduced reflectivity response of the crystal. To\nfacilitate the assignment of the observed relaxation to the decay of particular\nexcited electronic states we use pump pulses with central wavelengths ranging\nfrom 400 nm to 2.3 mum. Additionally, we examine the variation of parameters of\ncoherent A1g phonons upon the change of excitation and probing conditions. Data\nanalysis reveals a significant wavevector dependence of electron-hole and\nelectron- phonon coupling strength along \\Gamma--T direction of the Brillouin\nzone.",
        "positive": "Slabs of stabilized jellium: Quantum-size and self-compression effects: We examine thin films of two simple metals (aluminum and lithium) in the\nstabilized jellium model, a modification of the regular jellium model in which\na constant potential is added inside the metal to stabilize the system for a\ngiven background density. We investigate quantum-size effects on the surface\nenergy and the work function. For a given film thickness we also evaluate the\ndensity yielding energy stability, which is found to be slightly higher than\nthe equilibrium density of the bulk system and to approach this value in the\nlimit of thick slabs. A comparison of our self-consistent calculations with the\npredictions of the liquid-drop model shows the validity of this model."
    },
    {
        "anchor": "Composition and structure of Pd nanoclusters in SiO$_x$ thin film: The nucleation, distribution, composition and structure of Pd nanocrystals in\nSiO$_2$ multilayers containing Ge, Si, and Pd are studied using High Resolution\nTransmission Electron Microscopy (HRTEM) and X-ray Photoelectron Spectroscopy\n(XPS), before and after heat treatment. The Pd nanocrystals in the as deposited\nsample seem to be capped by a layer of PdO$_x$. A 1-2 eV shift in binding\nenergy was found for the Pd-3d XPS peak, due to initial state Pd to O charge\ntransfer in this layer. The heat treatment results in a decomposition of PdO\nand Pd into pure Pd nanocrystals and SiO$_2$.",
        "positive": "Ginzburg-Landau theory of crystalline anisotropy for bcc-liquid\n  interfaces: The weak anisotropy of the interfacial free-energy $\\gamma$ is a crucial\nparameter influencing dendritic crystal growth morphologies in systems with\natomically rough solid-liquid interfaces. The physical origin and quantitative\nprediction of this anisotropy are investigated for body-centered-cubic (bcc)\nforming systems using a Ginzburg-Landau theory where the order parameters are\nthe amplitudes of density waves corresponding to principal reciprocal lattice\nvectors. We find that this theory predicts the correct sign,\n$\\gamma_{100}>\\gamma_{110}$, and magnitude, $(\\gamma_{100}-\\gamma_{110}) /\n(\\gamma_{100}+\\gamma_{110})\\approx 1%$, of this anisotropy in good agreement\nwith the results of MD simulations for Fe. The results show that the\ndirectional dependence of the rate of spatial decay of solid density waves into\nthe liquid, imposed by the crystal structure, is a main determinant of\nanisotropy. This directional dependence is validated by MD computations of\ndensity wave profiles for different reciprocal lattice vectors for $\\{110\\}$\ncrystal faces. Our results are contrasted with the prediction of the reverse\nordering $\\gamma_{100}<\\gamma_{110}$ from an earlier formulation of\nGinzburg-Landau theory [Shih \\emph{et al.}, Phys. Rev. A {\\bf 35}, 2611\n(1987)]."
    },
    {
        "anchor": "Sparse expansions of multicomponent oxide configuration energy using\n  coherency & redundancy: Compressed sensing has become a widely accepted paradigm to construct high\ndimensional cluster expansion models used for statistical mechanical studies of\natomic configuration in complex multicomponent crystalline materials. However,\nstrict sampling requirements necessary to obtain minimal coherence measurements\nfor compressed sensing to guarantee accurate estimation of model parameters are\ndifficult and in some cases impossible to satisfy due to the inability of\nphysical systems to access certain configurations. Nevertheless, the dependence\nof energy on atomic configuration can still be adequately learned without these\nstrict requirements by using compressed sensing by way of coherent measurements\nusing redundant function sets known as frames. We develop a particular frame\nconstructed from the union of all occupancy-based cluster expansion basis sets.\nWe illustrate how using this highly redundant frame yields sparse expansions of\nthe configuration energy of complex oxide materials that are competitive and\noften surpass the prediction accuracy and sparsity of models obtained from\nstandard cluster expansions.",
        "positive": "Compensation of anisotropy in spin-Hall devices for neuromorphic\n  applications: Spintronic nano-oscillators with reduced non-linearity could offer key\nbenefits for realizing neuromorphic applications such as spike-based neurons\nand frequency multiplexing in neural networks. Here, we experimentally\ndemonstrate the reduction in non-linearity of a spin-Hall nano-oscillator\n(SHNO) by compensation of its effective magnetic anisotropy. The study involves\noptimization of Co/Ni multilayer growth to achieve the compensation, followed\nby spin diode measurements on patterned microstrips to quantify their\nanisotropy. The relation between the second ($H_{k2}$ = 0.47 mT) and the first\norder ($H_{k1}^{eff}$ = $-$0.8 mT) anisotropy fields reveals the existence of\nan easy cone, thereby validating the presence of compensation. Furthermore, we\ndemonstrate a synapse based on the compensated spin diode which has a fixed\nfrequency when the input power is varied. We then study the current-induced\nauto-oscillation properties of SHNOs on compensated films by patterning\nnano-constrictions of widths 200 and 100 nm. The invariance of the resonance\nfrequency and linewidth of the compensated SHNO with applied dc current\nindicates the absence of non-linearity. This independence is maintained\nirrespective of the applied external fields and its orientations. The\ncompensated SHNO obtained has a linewidth of 1.1 MHz and a peak output power of\nup to 1 pW/MHz emulating a nano-neuron with a low linewidth and a fixed\nfrequency."
    },
    {
        "anchor": "How disorder affects the Berry-phase anomalous Hall conductivity: the\n  view from k space: The anomalous Hall conductivity of \"dirty\" ferromagnetic metals is dominated\nby a Berry-phase contribution which is usually interpreted as an intrinsic\nproperty of the Bloch electrons in the pristine crystal. In this work we\nevaluate the geometric Hall current directly from the electronic ground state\nwith disorder, and then recast it as an integral over the crystalline Brillouin\nzone. The integrand is a generalized k-space Berry curvature, obtained by\nunfolding the Berry curvature from the small Brillouin zone of a large\nsupercell. Therein, disorder yields a net extrinsic Hall contribution, which we\nargue is related to the elusive side-jump effect. As an example, we unfold the\nfirst-principles Berry curvature of an Fe3Co ordered alloy from the original\nfcc-lattice Brillouin zone onto a bcc-lattice zone with four times the volume.\nComparison with the virtual-crystal Berry curvature clearly reveals the\nsymmetry-breaking effects of the substitutional Co atoms.",
        "positive": "Magneto-photoluminescence of exciton Rydberg states in monolayer WSe$_2$: Monolayer WSe$_2$ hosts a series of exciton Rydberg states denoted by the\nprincipal quantum number n = 1, 2, 3, etc. While most research focuses on their\nabsorption properties, their optical emission is also important but much less\nstudied. Here we measure the photoluminescence from the 1s - 5s exciton Rydberg\nstates in ultraclean monolayer WSe$_2$ encapsulated by boron nitride under\nmagnetic fields from -31 T to 31 T. The exciton Rydberg states exhibit similar\nZeeman shifts but distinct diamagnetic shifts from each other. From their\nluminescence spectra, Zeeman and diamagnetic shifts, we deduce the binding\nenergies, g-factors and radii of the 1s - 4s exciton states. Our results are\nconsistent with theoretical predictions and results from prior\nmagneto-reflection experiments."
    },
    {
        "anchor": "Growth rate and EBSD texture analysis of nitrogen doped diamond films: Chemical-Vapor-Deposition (CVD) diamond films were prepared using a variation\nof nitrogen addition into the gas source admixture by a direct current CVD\nmethod. The influence of nitrogen addition on the crystallographic texture and\ngrain shape evolution in heteroepitaxial polycrystalline diamond films was\ninvestigated using high-resolution electron backscattering diffraction\n(HR-EBSD) and X-ray diffraction (XRD). The analysis reveals that an addition of\n1.5% N2 to the CH4 gas flow leads to a strong enhancement of a {110} fiber\ntexture. The phenomenon is discussed in terms of a competitive growth selection\nmechanism.",
        "positive": "Simulation of the atomic structure near voids and estimation of their\n  growth rate anisotropy: We use a new variant of Molecular Static method for simulation of the atomic\nstructure near nanovoids. In our model an iterative procedure is employed, in\nwhich the atomic structure in the void vicinity and the parameter determining\nthe displacement of atoms embedded into an elastic continuum are obtained in a\nself-consistent manner. Results show that the atom displacements near nanovoids\nare significantly different for varies crystallographic directions in bcc\nmetals. Not long ago we have obtained an equation of vacancy diffusion under\nstrain. Now we use this equation and the atom displacements near nanovoids to\nevaluate shift of the void surface for varies crystallographic directions. We\nfind the equation for the normal component of the vacancy flux to the surface\nof the sphere for some crystallographic directions and then calculate shifting\nrate of the void surface element in mentioned directions for the different\nsupersaturations of the vacancies as a function of temperature."
    },
    {
        "anchor": "Anomalous low temperature specific heat of He-3 inside nanotube bundles: Helium atoms and hydrogen molecules can be strongly bound inside interstitial\nchannels within bundles of carbon nanotubes. An exploration of the low energy\nand low temperature properties of He-3 atoms is presented here. Recent study of\nthe analogous He-4 system has shown that the effect of heterogeneity is to\nyield a density of states N(E) that is qualitatively different from the\none-dimensional (1D) form of N(E) that would occur for an ideal set of\nidentical channels. In particular, the functional form of N(E) is that of a 4D\ngas near the very lowest energies and a 2D gas at somewhat higher energies.\nSimilar behavior is found here for He-3. The resulting thermodynamic behavior\nof this fermi system is computed, yielding an anomalous form of the heat\ncapacity and its dependence on coverage.",
        "positive": "Optimization of Magnetic Refrigerators by Tuning the Heat Transfer\n  Medium and Operating Conditions: A new experimental test bed has been designed, built, and tested to evaluate\nthe effect of the systems parameters on a reciprocating Active Magnetic\nRegenerator (AMR) near room temperature. Bulk gadolinium was used as the\nrefrigerant, silicon oil as the heat transfer medium, and a magnetic field of\n1.3 T was cycled. This study focuses on the methodology of single stage AMR\noperation conditions to get a higher temperature span near room temperature.\nHerein, the main objective is not to report the absolute maximum attainable\ntemperature span seen in an AMR system, but rather to find the systems optimal\noperating conditions to reach that maximum span. The results of this research\nshow that there is a optimal operating frequency, heat transfer fluid flow\nrate, flow duration, and displaced volume ratio in an AMR system. By optimizing\nthese parameters the refrigeration performance increased by 24%. It is expected\nthat such optimization will permit the design of a more efficient magnetic\nrefrigeration system."
    },
    {
        "anchor": "Point defects in models of amorphous silicon and their role in\n  structural relaxation: We have used tight-binding molecular-dynamics simulations to investigate the\nrole of point defects (vacancies and interstitials) on structural relaxation in\namorphous silicon. Our calculations give unambiguous evidence that point\ndefects can be defined in the amorphous solid, showing up as anomalies in the\nvalence-charge/Voronoi-volume relation. The changes in the radial distribution\nfunctions that take place during annealing are shown to be in close agreement\nwith recent, highly-accurate x-ray diffraction measurements. Our calculations\nprovide strong evidence that structural relaxation in a-Si proceeds by the\nmutual annihilation of vacancies and interstitials, i.e., local structural\nchanges rather than an overall relaxation of the network.",
        "positive": "The Observed Vibron Shift in Helium-Hydrogen Mixtures are due to Quantum\n  Nuclear and Localisation Effects, not bonding: The vibrational frequency of hydrogen molecules has been observed to increase\nstrongly with He concentration in helium hydrogen fluid mixtures. This has been\nassociated with He-H interactions, either directly through chemical bonding, or\nindirectly through increased local pressure. Here, we demonstrate that the\nincrease in the Raman frequency of the hydrogen molecule vibron is due to the\nnumber of H$_2$ molecules participating in the mode. There is no chemical\nbonding between He and H$_2$, helium acts only to separate the molecules. The\nvariety of possible environments for H$_2$ gives rise to many Raman active\nmodes, which causes broadening the vibron band. As the Raman active modes tend\nto be the lower frequency vibrons, these effects work together to produce the\nmajority of the shift seen in experiment. We used Density Functional Theory\n(DFT) methods in both solid and fluid phases to demonstrate this effect. DFT\nalso reveals that the pressure in these H$_2$-He mixture is primarily due to\nquantum nuclear effects, again the weak chemical bonding makes it a secondary\neffect."
    },
    {
        "anchor": "Physics and Nanofriction of Alkali Halide Solid Surfaces at the Melting\n  Point: Alkali halide (100) surfaces are anomalously poorly wetted by their own melt\nat the triple point. We carried out simulations for NaCl(100) within a simple\n(BMHFT) model potential. Calculations of the solid-vapor, solid-liquid and\nliquid-vapor free energies showed that solid NaCl(100) is a nonmelting surface,\nand that the incomplete wetting can be traced to the conspiracy of three\nfactors: surface anharmonicities stabilizing the solid surface; a large density\njump causing bad liquid-solid adhesion; incipient NaCl molecular correlations\ndestabilizing the liquid surface, reducing in particular its entropy much below\nthat of solid NaCl(100). Presently, we are making use of the nonmelting\nproperties of this surface to conduct case study simulations of hard tips\nsliding on a hot stable crystal surface. Preliminary results reveal novel\nphenomena whose applicability is likely of greater generality.",
        "positive": "A fiber-bundle model for the continuum deformation of brittle material: The deformation of brittle material is primarily accompanied by\nmicro-cracking and faulting. However, it has often been found that continuum\nfluid models, usually based on a non-Newtonian viscosity, are applicable. To\nexplain this rheology, we use a fiber-bundle model, which is a model of damage\nmechanics. In our analyses, yield stress was introduced. Above this stress, we\nhypothesize that the fibers begin to fail and a failed fiber is replaced by a\nnew fiber. This replacement is analogous to a micro-crack or an earthquake and\nits iteration is analogous to stick-slip motion. Below the yield stress, we\nassume that no fiber failure occurs, and the material behaves elastically. We\nshow that deformation above yield stress under a constant strain rate for a\nsufficient amount of time can be modeled as an equation similar to that used\nfor non-Newtonian viscous flow. We expand our rheological model to treat\nviscoelasticity and consider a stress relaxation problem. The solution can be\nused to understand aftershock temporal decay following an earthquake. Our\nresults provide justification for the use of a non-Newtonian viscous flow to\nmodel the continuum deformation of brittle materials."
    },
    {
        "anchor": "Cooperative domain type interlayer $sp^3$-bond formation in graphite: Using the classical molecular dynamics and the semiempirical Brenner's\npotential, we theoretically study the interlayer sigma bond formation, as\ncooperative and nonlinear phenomena induced by visible light excitations of a\ngraphite crystal. We have found several cases, wherein the excitations of\ncertain lattice sites result in new interlayer bonds even at non-excited sites.\nWe have also found that, a new interlayer bond is easier to be formed around a\nbond, if it is already existing. As many more sites are going to be excited,\nthe number of interlayer bonds increases nonlinearly with the number of excited\nsites. This nonlinearity shows 1.7 power of the total number of excited sites,\ncorresponding to about three- or four-photon process.",
        "positive": "Electric-field-induced changes of magnetic moments and\n  magnetocrystalline anisotropy in ultrathin cobalt films: In this study, the microscopic origins of the voltage-controlled magnetic\nanisotropy (VCMA) in 3d-ferromagnetic metals are revealed. Using in-situ X-ray\nfluorescence spectroscopy that provides a high quantum efficiency,\nelectric-field-induced changes in orbital magnetic moment and magnetic dipole\nTz terms in ultrathin Co films are demonstrated. An orbital magnetic moment\ndifference of 0.013{\\mu}B. was generated in the presence of electric fields of\n+(-)0.2 V/nm. The VCMA of Co was properly estimated by the induced change in\norbital magnetic moment, according to the perturbation theory model. The\ninduced change in magnetic dipole Tz term only slightly contributed to the VCMA\nin 3d-ferromagnetic metals."
    },
    {
        "anchor": "Competing structures in a minimal double-well potential model of\n  condensed matter: The microscopic structure of several amorphous substances often reveals\ncomplex patterns such as medium- or long-range order, spatial heterogeneity,\nand even local polycrystallinity. To capture all these features, models usually\nincorporate a refined description of the particle interaction which includes an\nad hoc design of the inside of the system constituents. We show that all these\nfeatures can emerge from a minimal two-dimensional model where particles\ninteract isotropically by a double-well potential, and have an excluded volume\nand a maximum coordination number. The rich variety of structural patterns\nshown by this simple model apply to a wide catalogue of real systems including\nwater, silicon, and different amorphous materials.",
        "positive": "Physical mechanisms of interface-mediated intervalley coupling in Si: The conduction band degeneracy in Si is detrimental to quantum computing\nbased on spin qubits, for which a nondegenerate ground orbital state is\ndesirable. This degeneracy is lifted at an interface with an insulator as the\nspatially abrupt change in the conduction band minimum leads to intervalley\nscattering. We present a theoretical study of the interface-induced valley\nsplitting in Si that provides simple criteria for optimal fabrication\nparameters to maximize this splitting. Our work emphasizes the relevance of\ndifferent interface-related properties to the valley splitting."
    },
    {
        "anchor": "Impact of Extreme Electrical Fields on Charge Density Distributions in\n  Alloys: The purpose of this work is to identify the field evaporation mechanism\nassociated with charge density distribution under extreme fields, linking atom\nprobe tomography (APT) experiments with density functional theory (DFT)\nmodeling. DFT is used to model a materials surface bonding, which affects the\nevaporation field of the surface atoms under high electric fields. We show how\nthe evaporation field of atoms is related to the charge density by comparing\nthe directionality and localization of the electrons with the evaporation of\nsingle ions versus dimers. This evaporation mechanism is important for the\nreconstruction of APT data, which is partially dependent on the input\nevaporation fields of the atoms. In $L1_{2}-Al_{3}Sc$, $Al-Al$ surface atoms\nare more likely to evaporate as dimers than $Al-Sc$ surface atoms. We find that\nthis is due to $Al-Al$ having a shared charge density, while $Al-Sc$ has an\nincreased density localized around the $Sc$ atom. Further, the role of\nsubsurface layers on the evaporation physics of the surface atoms as a function\nof charge density is considered. Beyond the practical considerations of\nimproving reconstruction of APT data, this work provides an approach for design\nof surface chemistry for extreme environments.",
        "positive": "Light-tunable charge density wave orders in MoTe2 and WTe2 single layers: By using constrained density functional theory modeling, we demonstrate that\nultrafast optical pumping unveils hidden charge orders in group VI monolayer\ntransition metal ditellurides. We show that irradiation of the insulating 2H\nphases stabilizes multiple transient charge density wave orders with\nlight-tunable distortion, periodicity, electronic structure and bandgap.\nMoreover, optical pumping of the semimetallic 1T' phases generates a transient\ncharge ordered metallic phase composed of 2D diamond clusters. For each\ntransient phase we identify the critical fluence at which it is observed and\nthe specific optical and Raman fingerprints to directly compare with future\nultrafast pump-probe experiments. Our work demonstrates that it is possible to\nstabilize charge density waves even in insulating 2D transition metal\ndichalcogenides by ultrafast irradiation."
    },
    {
        "anchor": "Van Der Waals Heteroepitaxy of GaSe and InSe, Quantum Wells and\n  Superlattices: Bandgap engineering and quantum confinement in semiconductor heterostructures\nprovide the means to fine-tune material response to electromagnetic fields and\nlight in a wide range of the spectrum. Nonetheless, forming semiconductor\nheterostructures on lattice-mismatched substrates has been a challenge for\nseveral decades, leading to restrictions for device integration and the lack of\nefficient devices in important wavelength bands. Here, we show that the van der\nWaals epitaxy of two-dimensional (2D) GaSe and InSe heterostructures occur on\nsubstrates with substantially different lattice parameters, namely silicon and\nsapphire. The GaSe/InSe heterostructures were applied in the growth of quantum\nwells and superlattices presenting photoluminescence and absorption related to\ninterband transitions. Moreover, we demonstrate a self-powered photodetector\nbased on this heterostructure on Si that works in the visible-NIR wavelength\nrange. Fabricated at wafer-scale, these results pave the way for an easy\nintegration of optoelectronics based on these layered 2D materials in current\nSi technology.",
        "positive": "Temperature induced first order electronic topological transition in\n  $\u03b2$-Ag$_2$Se: $\\beta$-Ag$_2$Se is a promising material for room temperature thermoelectric\napplications and magneto-resistive sensors. However, no attention was paid\nearlier to the hysteresis in the temperature dependence of resistivity\n($\\rho$($T$)). Here, we show that a broad hysteresis above 35 K is observed not\nonly in $\\rho$($T$), but also in other electronic properties such as Hall\ncoefficient ($R_H$($T$)), Seebeck coefficient, thermal conductivity and\nultraviolet photoelectron spectra (UPS). We also show that the hysteresis is\nnot associated with a structural transition. The $\\rho$($T$) and $R_H$($T$)\nshow that $\\beta$-Ag$_2$Se is semiconducting above 300 K, but metallicity is\nretained below 300 K. While electronic states are absent in the energy range\nfrom the Fermi level ($E_F$) to 0.4 eV below the $E_F$ at 300 K, a distinct\nFermi edge is observed in the UPS at 15 K suggesting that the $\\beta$-Ag$_2$Se\nundergoes an electronic topological transition from a high temperature\nsemiconducting state to a low temperature metallic state. Our study reveals\nthat a constant and moderately high thermoelectric figure of merit ($ZT$) in\nthe range 300-395 K is observed due to the broad semiconductor to metal\ntransition in $\\beta$-Ag$_2$Se."
    },
    {
        "anchor": "Ionization potentials in the limit of large atomic number: By extrapolating the energies of non-relativistic atoms and their ions with\nup to 3000 electrons within Kohn-Sham density functional theory, we find that\nthe ionization potential remains finite and increases across a row, even as\n$Z\\rightarrow\\infty$. The local density approximation becomes chemically\naccurate (and possibly exact) in some cases. Extended Thomas-Fermi theory\nmatches the shell-average of both the ionization potential and density change.\nExact results are given in the limit of weak electron-electron repulsion.",
        "positive": "Cross-linking of polyolefins : a study by thermoporosimetry with benzene\n  derivatives swelling solvents: o, m, p-xylene, p-dichlorobenzene, 1,2,4 trichlorobenzene and naphthalene\nwere calibrated as condensates used in thermoporosimetry technique. Exponential\nrelationships were found connecting the pore radii (Rp(nm)) and dT (C) on one\nside and the apparent energy of crystallization (Wa (J.cm-3)) and dT on the\nother side: Pore or mesh size distribution can be derived from DSC thermal\nrecording using the following equation: All the numerical parameter values were\ndetermined. Polyethylene and polypropylene samples, cross-linked with\nhigh-energy electrons or &#947;-rays, were submitted to thermoporosimetry\nstudy. The mesh size distributions (MSD) calculated for these polyolefins,\nusing o, m and p-xylene as solvent, were found in the same sequences that their\ndegrees of swelling and the irradiation doses they received."
    },
    {
        "anchor": "The importance of hole concentration in establishing carrier-mediated\n  ferromagnetism in Mn doped Ge: In the present work, we have prepared Mn-doped Ge using different annealing\napproaches after Mn ion implantation, and obtained samples with hole\nconcentrations ranging from 10^18 to 2.1x10^20 cm^-3, the latter being the\nhighest reported so far. Based on the magnetotransport properties of Mn doped\nGe, we argue that the hole concentration is a decisive parameter in\nestablishing carrier-mediated ferromagnetism in magnetic Ge.",
        "positive": "Current-induced electroresistance in Nd0.5Ca0.5Mn0.95Ni0.05O3: We have investigated the dc and pulsed current-induced electroresistance in\nphase separated manganite Nd0.5Ca0.5Mn0.95Ni0.05O3 (NCMONi05) as a function of\ntemperature and magnetic field. It is shown that the negative differential\nresistance which appears above a threshold current (Ic) and hysteresis in the\nV-I progressively vanish with increasing period of the current pulses. However\na strong non-linearity in V-I exists even for a pulse period of 6s. The peak\nvoltage at Ic decreases in magnitude and shifts towards higher current values\nwith increasing strength of the magnetic field. The strong nonlinear behavior\nand the negative differential resistance in the dc current sweep are\naccompanied by a rapid increase of the sample surface temperature and therefore\nprimarily arise from the Joule heating in the sample. While the Joule heating\nassists electroresistance in the high dc current regime, the nonlinearity in\nthe pulsed current sweep and the resistivity switching between a high and low\nvalue induced by controlling the width and period of pulses can not be\nexplained solely on the basis of Joule heating."
    },
    {
        "anchor": "Significant enhancement of hole mobility in [110] silicon nanowires\n  compared to electrons and bulk silicon: Utilizing sp3d5s* tight-binding band structure and wave functions for\nelectrons and holes we show that acoustic phonon limited hole mobility in [110]\ngrown silicon nanowires (SiNWs) is greater than electron mobility. The room\ntemperature acoustically limited hole mobility for the SiNWs considered can be\nas high as 2500 cm2/Vs, which is nearly three times larger than the bulk\nacoustically limited silicon hole mobility. It is also shown that the electron\nand hole mobility for [110] grown SiNWs exceed that of similar diameter [100]\nSiNWs, with nearly two orders of magnitude difference for hole mobility. Since\nsmall diameter SiNWs have been seen to grow primarily along [110] direction,\nresults strongly suggest that these SiNWs may be useful in future electronics.\nOur results are also relevant to recent experiments measuring SiNW mobility.",
        "positive": "Intrinsic spin Hall effect in monolayers of group-VI dichalcogenides: A\n  first-principles study: Using first-principles calculations within density functional theory, we\ninvestigate the intrinsic spin Hall effect in monolayers of group-VI\ntransition-metal dichalcogenides MX2 (M = Mo, W and X = S, Se). MX2 monolayers\nare direct band-gap semiconductors with two degenerate valleys located at the\ncorners of the hexagonal Brillouin zone. Because of the inversion symmetry\nbreaking and the strong spin-orbit coupling, charge carriers in opposite\nvalleys carry opposite Berry curvature and spin moment, giving rise to both a\nvalley- and a spin-Hall effect. The intrinsic spin Hall conductivity (ISHC) in\np-doped samples is found to be much larger than the ISHC in n-doped samples due\nto the large spin-splitting at the valence band maximum. We also show that the\nISHC in inversion-symmetric bulk dichalcogenides is an order of magnitude\nsmaller compared to monolayers. Our result demonstrates monolayer\ndichalcogenides as an ideal platform for the integration of valleytronics and\nspintronics."
    },
    {
        "anchor": "Magnetic and electronic properties of Eu$_5$In$_2$Sb$_6$: The intermetallic compound Eu$_5$In$_2$Sb$_6$, an antiferromagnetic material\nwith nonsymmorphic crystalline structure, is investigated by magnetic,\nelectronic transport and specific heat measurements. Being a Zintl phase,\ninsulating behavior is expected. Our thermodynamic and magnetotransport\nmeasurements along different crystallographic directions strongly indicate\npolaron formation well above the magnetic ordering temperatures. Pronounced\nanisotropies of the magnetic and transport properties even above the magnetic\nordering temperature are observed despite the Eu$^{2+}$ configuration which\ntestify to complex and competing magnetic interactions between these ions and\ngive rise to intricate phase diagrams discussed in detail. Our results provide\na comprehensive framework for further detailed study of this multifaceted\ncompound with possible nontrivial topology.",
        "positive": "Selecting Steady and Transient Photocurrent Response in BaTiO3 Films: The ferroelectric polarization and short-circuit photocurrent in BaTiO3 thin\nfilms have been studied for different contact configurations that allow to\nmeasure the photoresponse and polarization under the presence of large or\nnegligible imprint field. It is found that in all cases, the direction of the\nphotocurrent is dictated by the depolarizing field and ultimately by the film\npolarization, with a negligible contribution of the imprint electric field.\nHowever, dramatic differences are found in their time-dependent photoresponse.\nWhereas in presence of imprint, steady photocurrents are observed under\nsuitable illumination, transient photocurrents are generated in absence of\nimprint. It is argued that this distinct behavior is determined by the\ndifferent Schottky barrier height at electrodes which thus offers a simple way\nto tune the film photoresponse. These findings could be exploited for\nelectro-optic read-out and writing of ferroelectric memories."
    },
    {
        "anchor": "Raman and optical characterization of multilayer turbostratic graphene\n  grown via chemical vapor deposition: We synthesize large-area graphene via atmospheric-pressure (AP) chemical\nvapor deposition (CVD) on copper, and transfer to SiO2 wafers. In contrast to\nlow-pressure (LP) CVD on copper, optical contrast and atomic force microscopy\nmeasurements show AP-CVD graphene contains significant multi-layer areas. Raman\nspectroscopy always shows a single Lorentzian 2D peak, however systematic\ndifferences are observed in the 2D peak energy, width, and intensity for\nsingle- and multi-layer regions. We conclude that graphene multi-layers grown\nby AP-CVD on Cu are rotationally disordered.",
        "positive": "Structural Polymorphism Kinetics Promoted by Charged Oxygen Vacancies in\n  HfO$_2$: Defects such as oxygen vacancy are widely considered to be critical for the\nperformance of HfO2-based devices, and yet atomistic mechanisms underlying\nvarious exotic effects such as wake-up and fluid imprint remain elusive. Here,\nguided by a lattice-mode-matching criterion, we systematically study the phase\ntransitions between different polymorphs of hafnia under the influences of\nneutral and positively charged oxygen vacancies by mapping out the minimum\nenergy pathways using a first-principles-based variable-cell nudged elastic\nband technique. We find that the positively charged oxygen vacancy can\nsubstantially promote the transition of various nonpolar phases to the polar\nphase kinetically, enabled by a transient high-energy tetragonal phase and\nextreme charge-carrier-inert ferroelectricity of the polar $Pca2_1$ phase. The\nintricate coupling between structural polymorphism kinetics and the charge\nstate of the oxygen vacancy has important implications for the origin of\nferroelectricity in HfO$_2$-based thin films as well as wake-up, fluid imprint,\nand inertial switching."
    },
    {
        "anchor": "First-Principles Supercell Calculations of Small Polarons with Proper\n  Account for Long-Range Polarization Effects: We present a density functional theory (DFT) based supercell approach for\nmodeling small polarons with proper account for the long-range elastic response\nof the material. Our analysis of the supercell dependence of the polaron\nproperties (e.g., atomic structure, binding energy, and the polaron level)\nreveals long-range electrostatic effects and the electron-phonon interaction as\nthe two main contributors. We develop a correction scheme for DFT polaron\ncalculations that significantly reduces the dependence of polaron properties on\nthe DFT exchange-correlation functional and the size of the supercell in the\nlimit of strong electron-phonon coupling. Using our correction approach, we\npresent accurate all-electron full-potential DFT results for small polarons in\nrocksalt MgO and rutile TiO$_2$.",
        "positive": "Effect of Sm-, Gd- codoping on structural modifications in\n  aluminoborosilicate glasses under beta-irradiation: Two series of Sm-, Gd-codoped aluminoborosilicate glasses with different\ntotal rare earth content have been studied in order to examine the codoping\neffect on the structural modifications of beta-irradiated glasses. The data\nobtained by Electron Paramagnetic Resonance spectroscopy indicated that\nrelative amount of Gd3+ ions located in network former position reveals\nnon-linear dependence on Sm/Gd ratio. Besides, codoping leads to the evolution\nof the EPR signal attributed to defects created by irradiation: superhyperfine\nstructure of boron oxygen hole centres EPR line becomes less noticeable and\nresolved with increase of Gd amount. This fact manifests that Gd3+ ions are\nmainly diluted in vicinity of the boron network. By Raman spectroscopy, we\nshowed that the structural changes induced by the irradiation also reveal\nnon-linear behaviour with Sm/Gd ratio. In fact, the shift of the Si-O-Si\nbending vibration modes has a clear minimum for the samples containing equal\namount of Sm and Gd (50:50) in both series of the investigated glasses. In\ncontrast, for single doped glass there is no influence of dopant's content on\nSi-O-Si shift (in case of Gd) or its diminution (in case of Sm) occurs which is\nexplained by the reduction process influence. At the same time, no noticeable\neffect of codoping on Sm3+ intensity as well as on Sm2+ emission or on Sm\nreduction process was observed."
    },
    {
        "anchor": "Compressive sensing lattice dynamics. II. Efficient phonon calculations\n  and long-range interactions: We apply the compressive sensing lattice dynamics (CSLD) method to calculate\nphonon dispersion for crystalline solids. While existing methods such as frozen\nphonon, small displacement, and linear response are routinely applied for\nphonon calculations, they are considerable more expensive or cumbersome to\napply to certain solids, including structures with large unit cells or low\nsymmetry, systems that require more expensive electronic structure treatment,\nand polar semiconductors/insulators. In the latter case, we propose an approach\nbased on a corrected long-range force constant model with proper treatment of\nthe acoustic sum rule and the symmetric on-site force constant matrix. Our\napproach is demonstrated to be accurate and efficient for these systems through\ncase studies of NaCl, CeO$_2$, Y$_3$Al$_5$O$_{12}$ and La$_2$Fe$_{14}$B.",
        "positive": "Thermodynamics of the insulator-metal transition in dense liquid\n  deuterium: Recent dynamic compression experiments [M. D. Knudson et al., Science 348,\n1455 (2015); P. M. Celliers et al., Science 361, 677 (2018)] have observed the\ninsulator-metal transition in dense liquid deuterium, but with an approximately\n95 GPa difference in the quoted pressures for the transition at comparable\nestimated temperatures. It was claimed in the latter of these two papers that a\nvery large latent heat effect on the temperature was overlooked in the first,\nrequiring correction of those temperatures downward by a factor of two, thereby\nputting both experiments on the same theoretical phase boundary and reconciling\nthe pressure discrepancy. We have performed extensive path-integral molecular\ndynamics calculations with density functional theory to directly calculate the\nisentropic temperature drop due to latent heat in the insulator-metal\ntransition for dense liquid deuterium and show that this large temperature drop\nis not consistent with the underlying thermodynamics."
    },
    {
        "anchor": "Native point defects in $Ti_3GeC_2$ and $Ti_2GeC$: Using density functional theory, we calculated the formation energy of native\npoint defects (vacancies, interstitials and antisites) in MAX phase $Ti_2GeC$\nand $Ti_3GeC_2$ compounds. Ge vacancy with formation energy of 2.87 eV was the\nmost stable defect in $Ti_2GeC$ while C vacancy with formation energy of 2.47\neV was the most stable defect in $Ti_3GeC_2$. Ge vacancies, in particular, were\nfound to be strong phonon scattering centres that reduce the lattice\ncontribution to thermal conductivity in $Ti_2GeC$. In both compounds, the\nreported high thermal and electrical conductivity is attributed to the\nelectronic contribution that originates from the high density of states at the\nFermi level.",
        "positive": "Vibrational and mechanical properties of the highly mismatched (Cd,Be)Te\n  semiconductor alloy : Experiment and ab initio calculations: The (Cd, Be)Te semiconductor alloy that exhibits a dramatic mismatch in bond\ncovalency and stiffness clarifying its vibrational and mechanical properties is\nused as a benchmark to test the limits of the percolation model (PM) worked out\nto explain the complex Raman spectra of the related but less contrasted (Zn,\nBe) chalcogenides. The test is done by way of experiment (x smaller than 0.11)\ncombining Raman scattering with X ray diffraction at high pressure and ab\ninitio calculations (x around 0, 0.5 and 1). The (macroscopic) bulk modulus B\ndrops below the CdTe value on minor Be incorporation, at variance with a linear\nB versus x increase predicted ab initio, thus hinting at large anharmonic\neffects in the real crystal. Yet, no anomaly occurs at the microscopic (bond)\nscale as the regular bimodal PM Raman signal predicted ab initio for the BeTe\nbond in minority (x around 0 and 0.5) is (barely) detected experimentally.\nAlthough at large Be content (x around 1) the same bimodal signal relaxes down\nto inversion, an unprecedented case, specific pressure dependencies of the\nregular (x around 0 and 0.5) and inverted (x around 1) BeTe Raman doublets are\nin line with PM predictions. Hence, the PM applies as such to (Cd, Be)Te albeit\nin a relaxed form, without further refinement. This enhances the scheme\nvalidity as a generic descriptor of phonons in alloys."
    },
    {
        "anchor": "Mass coupling and $Q^{-1} of impurity-limited normal $^3$He in a torsion\n  pendulum: We present results of the $Q^{-1}$ and period shift, $\\Delta P$, for $^3$He\nconfined in a 98% nominal open aerogel on a torsion pendulum. The aerogel is\ncompressed uniaxially by 10% along a direction aligned to the torsion pendulum\naxis and was grown within a 400 $\\mu$m tall pancake (after compression) similar\nto an Andronikashvili geometry. The result is a high $Q$ pendulum able to\nresolve $Q^{-1}$ and mass coupling of the impurity-limited $^3$He over the\nwhole temperature range. After measuring the empty cell background, we filled\nthe cell above the critical point and observe a temperature dependent period\nshift, $\\Delta P$, between 100 mK and 3 mK that is 2.9$%$ of the period shift\n(after filling) at 100 mK. The $Q^{-1}$ due to the $^3$He decreases by an order\nof magnitude between 100 mK and 3 mK at a pressure of $0.14\\pm0.03$ bar. We\ncompare the observable quantities to the corresponding calculated $Q^{-1}$ and\nperiod shift for bulk $^3$He.",
        "positive": "Post-spinel transformations and equation of state in ZnGa2O4:\n  Determination at high-pressure by in situ x-ray diffraction: Room temperature angle-dispersive x-ray diffraction measurements on spinel\nZnGa2O4 up to 56 GPa show evidence of two structural phase transformations. At\n31.2 GPa, ZnGa2O4 undergoes a transition from the cubic spinel structure to a\ntetragonal spinel structure similar to that of ZnMn2O4. At 55 GPa, a second\ntransition to the orthorhombic marokite structure (CaMn2O4-type) takes place.\nThe equation of state of cubic spinel ZnGa2O4 is determined: V0 = 580.1(9) A3,\nB0 = 233(8) GPa, B0'= 8.3(4), and B0''= -0.1145 GPa-1 (implied value); showing\nthat ZnGa2O4 is one of the less compressible spinels studied to date. For the\ntetragonal structure an equation of state is also determined: V0 = 257.8(9) A3,\nB0 = 257(11) GPa, B0'= 7.5(6), and B0''= -0.0764 GPa-1 (implied value). The\nreported structural sequence coincides with that found in NiMn2O4 and MgMn2O4."
    },
    {
        "anchor": "Metal-insulator transition and giant anisotropic magnetoresistance in\n  ultra thin (Ga,Mn)As: MBE-grown, 5 nm-thick annealed Ga0.95Mn0.05As films with Tc~90K demonstrate\ntransition from metallic to insulating state below To~10K, where sheet\nresistances Rsh~h/e2 and both longitudinal Rxx and transverse Rxy components\nbecome comparable. Below metal-insulator transition we found giant anisotropic\nmagnetoresistance (GAMR), which depends on orientation of magnetization to\ncrystallographic axes and manifests itself in positive magnetoresistance near\n50% for Rxx at T=1.7K, H//[110] crystallographic direction and parallel to\ncurrent in contrast to smaller and negative magnetoresistance for H//\ndirection. We connect GAMR with anisotropic spin-orbit interaction resulting in\nformation of high- and low- resistance states with different localization along\nnon-equivalent easy axes.",
        "positive": "A complete ab initio view of Orbach and Raman spin-lattice relaxation in\n  a Dysprosium coordination compound: The unique electronic and magnetic properties of Lanthanides molecular\ncomplexes place them at the forefront of the race towards high-temperature\nsingle-ion magnets and magnetic quantum bits. The design of compounds of this\nclass has so far been almost exclusively driven by static crystal field\nconsiderations, with emphasis on increasing the magnetic anisotropy barrier.\nThis guideline has now reached its maximum potential and new progress can only\ncome from a deeper understanding of spin-phonon relaxation mechanisms. In this\nwork we compute relaxation times fully ab initio and unveil the nature of all\nspin-phonon relaxation mechanisms, namely Orbach and Raman pathways, in a\nprototypical Dy single-ion magnet. Computational predictions are in agreement\nwith the experimental determination of spin relaxation time and crystal field\nanisotropy, and show that Raman relaxation, dominating at low temperature, is\ntriggered by low-energy phonons and little affected by further engineering of\ncrystal field axiality. A comprehensive analysis of spin-phonon coupling\nmechanism reveals that molecular vibrations beyond the ion's first coordination\nshell can also assume a prominent role in spin relaxation through an\nelectrostatic polarization effect. Therefore, this work shows the way forward\nin the field by delivering a novel and complete set of chemically-sound design\nrules tackling every aspect of spin relaxation at any temperature"
    },
    {
        "anchor": "A model for exchange-biased asymmetric giant magneto-impedance in\n  amorphous wires: A model describing the exchange-biased asymmetric giant magneto-impedance in\nJoule-heated amorphous wires is proposed. It is assumed that the Joule heating\nresults in the formation of a surface hard magnetic crystalline layer, and the\nasymmetric giant magneto-impedance is related to the exchange coupling between\nthe amorphous and crystalline phases. The coupling between the surface layer\nand the amorphous bulk is described in terms of an effective bias field. The\nmodel is based on a simultaneous solution of linearizied Maxwell equations and\nthe Landau-Lifshitz equation. The calculated field and frequency dependences of\nthe wire impedance are in a qualitative agreement with results of the\nexperimental study of the asymmetric giant magneto-impedance in Joule-heated\nCo-based amorphous wires.",
        "positive": "Silicene Spintronics: Spintronics involves the study of active control and manipulation of spin\ndegrees of freedom in solid-state systems. The fascinating spin-resolved\nproperties of graphene motivate numerous researchers into the studies of\nspintronics in graphene and other two-dimensional (2D) materials. Silicene,\nsilicon analog of graphene, is considered as a promising material for\nspintronics. Here, we present a review on the theoretical advances about the\nspin-dependent properties including the electric field and exchange field\ntunable topological properties of silicene and the corresponding spintronic\ndevice simulations."
    },
    {
        "anchor": "Theoretical investigation on the transition metal borides with\n  Ta3B4-type structure: a class of hard and refractory materials: Based on density functional theory, we have systematically studied the\nstructural stability, mechanical properties and chemical bonding of the\ntransition metal borides M3B4 (M=Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W) for the\nfirst time. All the present studied M3B4 have been demonstrated to be\nthermodynamically and mechanically stable. The bulk modulus, shear modulus,\nYoung's modulus, Poisson's ratio, microhardness, Debye temperature and\nanisotropy have been derived for ideal polycrystalline M3B4 aggregates. In\naddition, the relationship between Debye temperature and microhardness has been\ndiscussed for these isostructral M3B4. Furthermore, the results of the Cauchy\npressure, the ratio of bulk modulus to shear modulus, and Poisson's ratio\nsuggest that the valence electrons of transition metals play an important role\nin the ductility of M3B4. The calculated total density of states for M3B4\nindicates that all these borides display a metallic conductivity. By analyzing\nthe electron localization function, we show that the improvement of the\nductility in these M3B4 might attribute to the decrease of their angular\nbonding character.",
        "positive": "Photoluminescence of InGaAs/GaAsBi/InGaAs type-II quantum well grown by\n  gas source molecular beam epitaxy: InGaAs/GaAsBi/InGaAs quantum wells (QWs) were grown on GaAs substrates by gas\nsource molecular beam epitaxy for realizing the type II band-edge line-up. Both\ntype I and type II transitions were observed in the Bi containing W QWs and the\nphotoluminescence intensity was enhanced in the sample with a high Bi content,\nwhich is mainly due to the improvement of carrier confinement. Blue-shift of\ntype II transitions at high excitation power density was observed and ascribed\nto the band-bending effect. The calculated transition energies based on 8 band\nk.p model fit well with the experiment results. The experimental and\ntheoretical results show that the type-II QW design is a new promising\ncandidate for realizing long wavelength GaAs-based light emitting devices near\n1.3 um."
    },
    {
        "anchor": "Operability timescale of defect-engineered graphene: Defects in the lattice are of primal importance to tune graphene chemical,\nthermal and electronic properties. Electron-beam irradiation is an easy method\nto induce defects in graphene following pre-designed patterns, but no\nsystematic study of the time evolution of the resulting defects is available.\nIn this paper, the change over time of defected sites created in graphene with\nlow-energy ($\\leq 20$ keV) electron irradiation is studied both experimentally\nvia micro-Raman spectroscopy for a period of $6\\times 10^3$ hours and through\nmolecular dynamics simulations. During the first 10 h, the structural defects\nare stable at the highest density value. Subsequently, the crystal partially\nreconstructs, eventually reaching a stable, less defected condition after more\nthan one month. The simulations allow the rationalization of the processes at\nthe atomic level and confirm that the irradiation induces composite clusters of\ndefects of different nature rather than well-defined nanoholes as in the case\nof high-energy electrons. The presented results identify the timescale of the\ndefects stability, thus establishing the operability timespan of engineerable\ndefect-rich graphene devices with applications in nanoelectronics. Moreover,\nlong-lasting chemical reactivity of the defective graphene is pointed out. This\nproperty can be exploited to functionalize graphene for sensing and energy\nstorage applications.",
        "positive": "Ultrafast charge dynamics and photoluminescence in bilayer MoS2: Our examination of the interplay of ultrafast charge dynamics and\nelectron-phonon interaction in bilayer MoS2 provides a microscopic basis for\nunderstanding the features (two peaks) in the emission spectrum. We demonstrate\nthat while the initial accumulation of excited charge occurs at and near the Q\npoint of the two-dimensional Brillioun zone, emission takes place predominantly\nthrough two pathways: direct charge recombination at the K point and indirect\nphonon-assisted recombination of electrons at the K valley and holes at\n{\\Gamma} hill of the Brillouin zone. Analysis of the wave vector dependencies\nof the electron-phonon interaction traces the higher energy peak to\nphonon-assisted relaxation of the excited electrons from the Q to the K valley\nin the conduction band. Our results thus reveal the importance of ultrafast\ncharge dynamics in understanding photoemissive properties of a few-layer\ntransition-metal dichalcogenide. These calculations are based on time dependent\ndensity functional theory in the density matrix formulation."
    },
    {
        "anchor": "Atomic positions independent descriptor for machine learning of material\n  properties: The high-throughput screening of periodic inorganic solids using machine\nlearning methods requires atomic positions to encode structural and\ncompositional details into appropriate material descriptors. These atomic\npositions are not available {\\it a priori} for new materials which severely\nlimits exploration of novel materials. We overcome this limitation by using\nonly crystallographic symmetry information in the structural description of\nmaterials. We show that for materials with identical structural symmetry,\nmachine learning is trivial and accuracies similar to that of density\nfunctional theory calculations can be achieved by using only atomic numbers in\nthe material description. For machine learning of formation energies of bulk\ncrystalline solids, this simple material descriptor is able to achieve\nprediction mean absolute errors of only 0.07 eV/atom on a test dataset\nconsisting of more than 85,000 diverse materials. This atomic-position\nindependent material descriptor presents a new route of materials discovery\nwherein millions of materials can be screened by training a machine learning\nmodel over a drastically reduced subspace of materials.",
        "positive": "Unique prospects of graphene-based THz modulators: The modulation depth of 2-D electron gas (2DEG) based THz modulators using\nAlGaAs/GaAs heterostructures with metal gates is inherently limited to < 30%.\nThe metal gate not only attenuates the THz signal (> 90%) but also severely\ndegrades the modulation depth. The metal losses can be significantly reduced\nwith an alternative material with tunable conductivity. Graphene presents a\nunique solution to this problem due to its symmetric band structure and\nextraordinarily high mobility of holes that is comparable to electron mobility\nin conventional semiconductors. The hole conductivity in graphene can be\nelectrostatically tuned in the graphene-2DEG parallel capacitor configuration,\nthus more efficiently tuning the THz transmission. In this work, we show that\nit is possible to achieve a modulation depth of > 90% while simultaneously\nminimizing signal attenuation to < 5% by tuning the Fermi level at the Dirac\npoint in graphene."
    },
    {
        "anchor": "Microstructure of precipitates and magnetic domain structure in an\n  annealed Co38Ni33Al29 shape memory alloy: The microstructure of a CoNiAl FSMA was determined by conventional\ntransmission electron microscopy, electron diffraction studies together with\nadvanced microscopy techniques and in-situ Lorentz microscopy. 10 to 60 nm\nsized rod-like precipitates of hcp $\\epsilon$-Co were confirmed to be present\nby HRTEM. The orientation relationship between the precipitates and B2 matrix\nis described by the Burgers orientation relationship. The crystal structure of\nthe martensite obtained after cooling is tetragonal L10 with a (1-11) twinning\nplane. The magnetic domain structure was determined during an in-situ cooling\nexperiment using the Fresnel mode of Lorentz microscopy. While transformation\nproceeds from B2 austenite to L10 martensite, new domains are nucleated leading\nto a decrease in domain width, with the magnetization lying predominantly along\na single direction. It was possible to completely describe the relationship\nbetween magnetic domains and crystallographic directions in the austenite phase\nthough complications existed for the martensite phase.",
        "positive": "Crystal Structures of Ni$_2$MnGa from Density Functional Calculations: The different crystal structures of ferromagnetic Ni$_2$MnGa have been\ncalculated using density functional theory (DFT) with special emphasis on the\nmodulated structures 10M and 14M. These are important for understanding the\nstability of Ni$_2$MnGa martensites and their functionality as shape-memory\nmaterials. The modulated structures have been optimized in the calculations and\ntheir properties are discussed in relation to the structures without\nmodulation. The occurrence of the modulated structures is related to the soft\nTA$_2$ phonon mode observed in Ni$_2$MnGa. The latter is related to the\nspecific nesting behavior of the Fermi surface in Ni$_2$MnGa. Particular shapes\nof the modulated structures are stabilized by the covalent interaction mediated\nby the \\textit{p}-orbitals of Ga and \\textit{d}-orbitals of Ni. The role of\nthis interaction becomes clear seen when considering the phonon dispersion\nspectrum of Ni$_2$MnGa, where some characteristic anomalies occur in the\ncoupling of acoustical vibrational modes and the optical modes of Ni."
    },
    {
        "anchor": "Scanning tunneling microscopy and spectroscopy at low temperatures of\n  the (110) surface of Te doped GaAs single crystals: We have performed voltage dependent imaging and spatially resolved\nspectroscopy on the (110) surface of Te doped GaAs single crystals with a low\ntemperature scanning tunneling microscope (STM). A large fraction of the\nobserved defects are identified as Te dopant atoms which can be observed down\nto the fifth subsurface layer. For negative sample voltages, the dopant atoms\nare surrounded by Friedel charge density oscillations. Spatially resolved\nspectroscopy above the dopant atoms and above defect free areas of the GaAs\n(110) surface reveals the presence of conductance peaks inside the\nsemiconductor band gap. The appearance of the peaks can be linked to charges\nresiding on states which are localized within the tunnel junction area. We show\nthat these localized states can be present on the doped GaAs surface as well as\nat the STM tip apex.",
        "positive": "Magnetic phase diagram of low-doped La{2-x}SrxCuO4 thin films studied by\n  low-energy muon-spin rotation: The magnetic phase diagram of La2-xSrxCuO4 thin-films grown on single-crystal\nLaSrAlO4 substrates has been determined by low-energy muon-spin rotation. The\ndiagram shows the same features as the one of bulk La2-xSrxCuO4, but the\ntransition temperatures between distinct magnetic states are significantly\ndifferent. In the antiferromagnetic phase the Neel temperature TN is strongly\nreduced, and no hole spin freezing is observed at low temperatures. In the\ndisordered magnetic phase (x>0.02) the transition temperature to the cluster\nspin-glass state Tg is enhanced. Possible reasons for the pronounced\ndifferences between the magnetic phase diagrams of thin-film and bulk samples\nare discussed."
    },
    {
        "anchor": "Clear variation of spin splitting by changing electron distribution at\n  non-magnetic metal/Bi2O3 interfaces: Large spin splitting at Rashba interface, giving rise to strong spin-momentum\nlocking, is essential for efficient spin-to-charge conversion. Recently, a\nCu/Bismuth oxide (Bi2O3) interface has been found to exhibit an efficient\nspin-to-charge conversion similar to a Ag/Bi interface with large Rashba spin\nsplitting. However, the guiding principle of designing the metal/oxide\ninterface for the efficient conversion has not been clarified yet. Here we\nreport strong non-magnetic (NM) material dependence of spin splitting at\nNM/Bi2O3 interfaces. We employed spin pumping technique to inject spin current\ninto the interface and evaluated the magnitude of interfacial spin-to-charge\nconversion. We observed large modulation and sign change in conversion\ncoefficient which corresponds to the variation of spin splitting. Our\nexperimental results together with first-principles calculations indicate that\nsuch large variation is caused by material dependent electron distribution near\nthe interface. The results suggest that control of interfacial electron\ndistribution by tuning the difference in work function across the interface may\nbe an effective way to tune the magnitude and sign of spin-to-charge conversion\nand Rashba parameter at interface.",
        "positive": "Structural transition and re-emergence of iron's total electron spin in\n  (Mg,Fe)O at ultrahigh pressure: Fe-bearing MgO [(Mg$_{1-x}$Fe$_x$)O] is considered a major constituent of\nterrestrial exoplanets. Crystallizing in the B1 structure in the Earth's lower\nmantle, (Mg$_{1-x}$Fe$_x$)O undergoes a high-spin ($S=2$) to low-spin ($S=0$)\ntransition at $\\sim$45 GPa, accompanied by anomalous changes of this mineral's\nphysical properties, while the intermediate-spin ($S=1$) state has not been\nobserved. In this work, we investigate (Mg$_{1-x}$Fe$_x$)O ($x \\leq 0.25$) up\nto $1.8$ TPa via first-principles calculations. Our calculations indicate that\n(Mg$_{1-x}$Fe$_x$)O undergoes a simultaneous structural and spin transition at\n$\\sim$0.6 TPa, from the B1 phase low-spin state to the B2 phase\nintermediate-spin state, with Fe's total electron spin $S$ re-emerging from $0$\nto $1$ at ultrahigh pressure. Upon further compression, an intermediate-to-low\nspin transition occurs in the B2 phase. Depending on the Fe concentration\n($x$), metal$-$insulator transition and rhombohedral distortions can also occur\nin the B2 phase. These results suggest that Fe and spin transition may affect\nplanetary interiors over a vast pressure range."
    },
    {
        "anchor": "Casimir repulsion in moving media: Casimir-Lifshitz interaction emerging from relative movement of layers in\nstratified dielectric media (e.g., non-uniformly moving fluids) is considered.\nIt is shown that such movement may result in a repulsive Casimir-Lifshitz force\nexerted on the layers, with the simplest possible structure consisting of three\nadjacent layers of the same dielectric medium, where the middle one is\nstationary and the other two are sliding along a direction parallel to the\ninterfaces of the layers.",
        "positive": "Robust magnetic proximity induced anomalous Hall effect in a room\n  temperature van der Waals ferromagnetic semiconductor based 2D\n  heterostructure: Developing novel high-temperature van der Waals ferromagnetic semiconductor\nmaterials and investigating their interface coupling effects with\ntwo-dimensional topological semimetals are pivotal for advancing\nnext-generation spintronic and quantum devices. However, most van der Waals\nferromagnetic semiconductors exhibit ferromagnetism only at low temperatures,\nlimiting the proximity research on their interfaces with topological\nsemimetals. Here, we report an intrinsic, van der Waals layered\nroom-temperature ferromagnetic semiconductor crystal, FeCr0.5Ga1.5Se4 (FCGS),\nwith a Curie temperature as high as 370 K, setting a new record for van der\nWaals ferromagnetic semiconductors. The saturation magnetization at low\ntemperature (2 K) and room temperature (300 K) reaches 8.2 emu/g and 2.7 emu/g,\nrespectively. Furthermore, FCGS possesses a bandgap of approximately 1.2 eV,\nwhich is comparable to the widely used commercial silicon. The FCGS/graphene\nheterostructure exhibits an impeccably smooth and gapless interface, thereby\ninducing a robust magnetic proximity coupling effect between FCGS and graphene.\nAfter the proximity coupling, graphene undergoes a charge carrier transition\nfrom electrons to holes, accompanied by a transition from non-magnetic to\nferromagnetic transport behavior with robust anomalous Hall effect. Notably,\nthe anomalous Hall effect remains robust even temperatures up to 400 K."
    },
    {
        "anchor": "Multiferroic CuCrO2 under High Pressure: In-Situ X-Ray Diffraction and\n  Raman Spectroscopic Studies: The compression behavior of delafossite compound CuCrO2 has been investigated\nby in-situ x-ray diffraction and Raman spectroscopic measurements upto 23.2 and\n34 GPa respectively. X-ray diffraction data shows the stability of ambient\nrhombohedral structure upto ~ 23 GPa. Material shows large anisotropy in axial\ncompression with c-axis compressibility, c= 1.2610-3(1) GPa-1 and a-axis\ncompressibility, a= 8.9010-3(6) GPa-1. Our XRD data shows an irreversible\nbroadening of diffraction peaks. Pressure volume data when fitted to 3rd order\nBirch-Murnaghan equation of state gives the value of bulk modulus, B0 =\n156.7(2.8) GPa with its pressure derivative, B0' as 5.3(0.5). All the observed\nvibrational modes in Raman measurements show hardening with pressure.\nAppearance of a new mode at ~24 GPa indicates the structural phase transition\nin the compound. Our XRD and Raman results indicate that CuCrO2 may be\ntransforming to an ordered rocksalt type structure under compression.",
        "positive": "Can an amorphous crystallize into a high entropy alloy?: On the premise that amorphous-HEA composites could demonstrate high toughness\nand resistance to embrittlement akin to the phase separating glassy-solid\nsolution composites, we develop a thermodynamics based approach to identify\nchemical compositions capable of undergoing the amorphous to HEA\ntransformation. We introduce two new parameters called phase selection value\n(PSV) and molar volume dispersity parameter. Using this thermodynamic approach\nseven multi-component compositions were proposed and the general guidelines for\nidentifying such compositions was established. The approach also reveals that\nBMGs may not be as such amenable to undergo an amorphous to HEA transformation."
    },
    {
        "anchor": "High versus low energy ion irradiation impact on functional properties\n  of PLD-grown alumina coatin: It is well known that ion irradiation can be successfully used to reproduce\nmicrostructural features triggered by neutron irradiation. Even though the\nirradiation process brings many benefits, it is also associated with several\ndrawbacks. For example, the penetration depth of the ion in the material is\nvery limited. This is particularly important for energies below MeV, ultimately\nreducing the number of available irradiation facilities. In addition to that,\nextracting information exclusively from the modified volume may be challenging.\nTherefore, extreme caution must be taken when interpreting obtained data. Our\nwork aims to compare the findings of nanomechanical studies already conducted\nseparately on thin amorphous ceramic coatings irradiated with ions of different\nenergies, hence layers of different thicknesses. In this work, we show that in\nsome instances, the 10% rule may be obeyed. In order to prove our finding, we\ncompared results obtained for ion irradiated (with two energies: 0.25 and 1.2\nMeV up to 25dpa) alumina coating system. Mechanical properties of pristine and\nion-irradiated specimens were studied by nanoindentation technique.\nInterestingly, the qualitative relationship between nanohardness and\nirradiation damage level is very similar, regardless of the energy used. The\npresented work proves that for some materials (e.g., hard coatings), the\nqualitative assessment of the mechanical changes using nanoindentation might be\nfeasible even for shallow implantation depths.",
        "positive": "Experimental and theoretical determination of \u03c3-bands on\n  (\"2$\\sqrt{3}$x2$\\sqrt{3}$\") silicene grown on Ag(111): Silicene, the two-dimensional (2D) allotrope of silicon has very recently\nattracted a lot of attention. It has a structure that is similar to graphene\nand it is theoretically predicted to show the same kind of electronic\nproperties which has put graphene into the focus of large research and\ndevelopment projects world-wide. In particular, a 2D structure made from Si is\nof high interest because of the application potential in Si-based electronic\ndevices. However, so far there is not much known about the silicene band\nstructure from experimental studies. A comprehensive study is here presented of\nthe atomic and electronic structure of the silicene phase on Ag(111) denoted as\n(2$\\sqrt{3}$x2$\\sqrt{3}$)R30{\\deg} in the literature. Low energy electron\ndiffraction (LEED) shows an unconventional rotated (\"2$\\sqrt{3}$x2$\\sqrt{3}$\")\npattern with a complicated set of split diffraction spots. Scanning tunneling\nmicroscopy (STM) results reveal a Ag(111) surface that is homogeneously covered\nby the (\"2$\\sqrt{3}$x2$\\sqrt{3}$\") silicene which exhibits an additional\nquasi-periodic long range ordered superstructure. The complex structure,\nrevealed by STM, has been investigated in detail and we present a consistent\npicture of the silicene structure based on both STM and LEED. The homogeneous\ncoverage by the (\"2$\\sqrt{3}$x2$\\sqrt{3}$\") silicene facilitated an\nangle-resolved photoelectron spectroscopy study which reveals a silicene band\nstructure of unprecedented detail. Here, we report four silicene bands which\nare compared to calculated dispersions based on a relaxed\n(2$\\sqrt{3}$x2$\\sqrt{3}$) model. We find good qualitative agreement between the\nexperimentally observed bands and calculated silicene bands of {\\sigma}\ncharacter."
    },
    {
        "anchor": "High Van Hove singularity extension and Fermi velocity increase in\n  epitaxial graphene functionalized by gold clusters intercalation: Gold intercalation between the buffer layer and a graphene monolayer of\nepitaxial graphene on SiC(0001) leads to the formation of quasi free standing\nsmall aggregates of clusters. Angle Resolved Photoemission Spectroscopy\nmeasurements reveal that these clusters preserve the linear dispersion of the\ngraphene quasiparticles and surprisingly increase their Fermi velocity. They\nalso strongly modify the band structure of graphene around the Van Hove\nsingularities (VHs) by a strong extension without charge transfer. This result\ngives a new insight on the role of the intercalant in the renormalization of\nthe bare electronic band structure of graphene usually observed in Graphite and\nGraphene Intercalation Compounds.",
        "positive": "Large Thermoelectric Power Factor in Whisker Crystals of Solid Solutions\n  of the One-Dimensional Tellurides Ta4SiTe4 and Nb4SiTe4: One-dimensional tellurides Ta4SiTe4 and Nb4SiTe4 were found to show high\nthermoelectric performance below room temperature. This study reported the\nsynthesis and thermoelectric properties of whisker crystals of\nTa4SiTe4-Nb4SiTe4 solid solutions and Mo- or Ti-doped (Ta0.5Nb0.5)4SiTe4.\nThermoelectric power of the solid solutions systematically increased with\nincreasing Ta content, while their electrical resistivity was unexpectedly\nsmall. Mo- and Ti-doped (Ta0.5Nb0.5)4SiTe4 showed n- and p-type thermoelectric\nproperties with large power factors exceeding 40 microW cm-1 K-2, respectively.\nThe fact that not only Ta4SiTe4 and Nb4SiTe4 but also their solid solutions\nshowed high performance indicated that this system is a promising candidate for\nthermoelectric applications at low temperatures."
    },
    {
        "anchor": "Interfacial charge transfer and interaction in the MXene/TiO2\n  heterostructures: Hybrid materials of MXenes (2D carbides and nitrides) and transition-metal\noxides (TMOs) have shown great promise in electrical energy storage and 2D\nheterostructures have been proposed as the next-generation electrode materials\nto expand the limits of current technology. Here we use first principles\ndensity functional theory to investigate the interfacial structure, energetics,\nand electronic properties of the heterostructures of MXenes (Tin+1CnT2;\nT=terminal groups) and anatase TiO2. We find that the greatest work-function\ndifferences are between OH-terminated-MXene (1.6 eV) and anatase TiO2(101) (6.4\neV), resulting in the largest interfacial electron transfer (~0.9 e/nm2 across\nthe interface) from MXene to the TiO2 layer. This interface also has the\nstrongest adhesion and further strengthened by hydrogen bond formation. For O-,\nF-, or mixed O-/F- terminated Tin+1Cn MXenes, electron transfer is minimal and\ninterfacial adhesion is weak for their heterostructures with TiO2. The strong\ndependence of the interfacial properties of the MXene/TiO2 heterostructures on\nthe surface chemistry of the MXenes will be useful to tune the heterostructures\nfor electric-energy-storage applications.",
        "positive": "Orientation-dependent surface composition of in situ annealed strontium\n  titanate: The surface composition of polycrystalline niobium-doped strontium titanate\n(SrTiO3 : Nb) is studied using X-ray photoelectron emission microscopy (XPEEM)\nfor many grain orientations in order to characterise the surface chemistry with\nhigh spatial resolution. The surface sensitivity is maximised by the use of\nsoft X-ray synchrotron radiation (SR). The grain orientation is determined by\nelectron backscattering diffraction (EBSD). Stereographic plots are used to\nshow the correlation between surface composition and orientation for several\ngrains. Predominant surface terminations are assigned to major orientations."
    },
    {
        "anchor": "Cyclotron resonance and Faraday rotation in graphite: The optical conductivity of graphite in quantizing magnetic fields is\nanalytically evaluated for frequencies in the range of 10--300 meV, where the\nelectron relaxation processes can be neglected and the low-energy excitations\nat the \"Dirac lines\" are more essential. The conductivity peaks are explained\nin terms of the electron transitions in graphite.\n  Conductivity calculated per one graphite layer tends on average to the\nuniversal conductivity of graphene while the frequency is larger than the\nLandau spacing.\n  The (semi)metal-insulator transformation is possible under doping in high\nmagnetic fields.",
        "positive": "Hubbard $U$ through polaronic defect states: Since the preliminary work of Anisimov and co-workers, the Hubbard corrected\nDFT+$U$ functional has been used for predicting properties of correlated\nmaterials by applying on-site effective Coulomb interactions to specific\norbitals. However, the determination of the Hubbard $U$ parameter has remained\nunder intense discussion despite the multitude of approaches proposed. Here, we\ndefine a selection criterion based on the use of polaronic defect states for\nthe enforcement of the piecewise linearity of the total energy upon electron\noccupation. A good agreement with results from piecewise linear hybrid\nfunctionals is found for the electronic and structural properties of polarons,\nincluding the formation energies. The values of $U$ determined in this way are\nfound to give a robust description of the polaron energetics upon variation of\nthe considered state. In particular, we also address a polaron hopping pathway,\nfinding that the determined value of $U$ leads to accurate energetics without\nrequiring a configurational-dependent $U$. It is emphasized that the selection\nof $U$ should be based on physical properties directly associated with the\norbitals to which $U$ is applied, rather than on more global properties such as\nband gaps and band widths. For comparison, we also determine $U$ through a\nwell-established linear-response scheme finding noticeably different values of\n$U$ and consequently different formation energies. Possible origins of these\ndiscrepancies are discussed. As case studies, we consider the self-trapped\nelectron in BiVO$_4$, the self-trapped hole in MgO, the Li-trapped hole in MgO,\nand the Al-trapped hole in $\\alpha$-SiO$_2$."
    },
    {
        "anchor": "Magnetic structure and magnetoelectric coupling in bulk and thin film\n  FeVO$_4$: We have investigated the magnetoelectric and magnetodielectric response in\nFeVO$_4$, which exhibits a change in magnetic structure coincident with\nferroelectric ordering at $T_{N2}$$\\approx$15 K. Using symmetry considerations,\nwe construct a model for the possible magnetoelectric coupling in this system,\nand present a discussion of the allowed spin structures in FeVO$_4$. Based on\nthis model, in which the spontaneous polarization is caused by a trilinear\nspin-phonon interaction, we experimentally explore the magnetoelectric coupling\nin FeVO$_4$ thin films through measurements of the electric field induced shift\nof the multiferroic phase transition temperature, which exhibits an increase of\n0.25 K in an applied field of 4 MV/m. The strong spin-charge coupling in \\fvo\\,\nis also reflected in the significant magnetodielectric shift, which is present\nin the paramagnetic phase due to a quartic spin-phonon interaction and shows a\nmarked enhancement with the onset of magnetic order which we attribute to the\ntrilinear spin-phonon interaction. We observe a clear magnetic field induced\ndielectric anomaly at lower temperatures, distinct from the sharp peak\nassociated with the multiferroic transition, which we tentatively assign to a\nspin reorientation cross-over. We also present a magnetoelectric phase diagram\nfor FeVO$_4$.",
        "positive": "Ferroelectricity in [111]-oriented epitaxially strained SrTiO$_3$ from\n  first principles: We use first principles density functional theory calculations to investigate\nthe effect of biaxial strain in the low-temperature structural and\nferroelectric properties of [111]-oriented SrTiO$_3$. We find that [111]\nbiaxial strain, achievable by coherent epitaxial growth along the [111]\ndirection, induces structural distortions in SrTiO$_3$ that are not present in\neither bulk or [001]-oriented SrTiO$_3$. Under [111] biaxial strain, SrTiO$_3$\ndisplays ferroelectricity at tensile strain, and paraelectricity at compressive\nstrain. We compute the phonon spectrum and macroscopic polarization of\nSrTiO$_3$ as a function of [111] biaxial strain, and relate our results to the\npredictions of the free energy phenomenological model of Pertsev, Tagantsev and\nSetter [Phys. Rev. B 61, 825 (2000); Phys. Rev. B 65, 219901 (2002)]."
    },
    {
        "anchor": "Mesoscopic Stacking Reconfigurations in Stacked van der Waals Film: Mesoscopic-scale stacking reconfigurations are investigated when van der\nWaals films are stacked. We have developed a method to visualize complicated\nstacking structures and mechanical distortions simultaneously in stacked\natom-thick films using Raman spectroscopy. In the rigid limit, we found that\nthe distortions originate from the transfer process, which can be understood\nthrough thin film mechanics with a large elastic property mismatch. In\ncontrast, with atomic corrugations, the in-plane strain fields are more closely\ncorrelated with the stacking configuration, highlighting the impact of atomic\nreconstructions on the mesoscopic scale. We discovered that the grain\nboundaries don`t have a significant effect while the cracks are causing\ninhomogeneous strain in stacked polycrystalline films. This result contributes\nto understanding the local variation of emerging properties from moir\\'e\nstructures and advancing the reliability of stacked vdW material fabrication.",
        "positive": "Superconductivity in single-crystalline, aluminum- and\n  gallium-hyperdoped germanium: Superconductivity in group IV semiconductors is desired for hybrid devices\ncombining both semiconducting and superconducting properties. Following boron\ndoped diamond and Si, superconductivity has been observed in gallium doped Ge,\nhowever the obtained specimen is in polycrystalline form [Herrmannsd\\\"orfer et\nal., Phys. Rev. Lett. 102, 217003 (2009)]. Here, we present superconducting\nsingle-crystalline Ge hyperdoped with gallium or aluminium by ion implantation\nand rear-side flash lamp annealing. The maximum concentration of Al and Ga\nincorporated into substitutional positions in Ge is eight times higher than the\nequilibrium solid solubility. This corresponds to a hole concentration above\n10^21 cm-3. Using density functional theory in the local density approximation\nand pseudopotential plane-wave approach, we show that the superconductivity in\np-type Ge is phonon-mediated. According to the ab initio calculations the\ncritical superconducting temperature for Al- and Ga-doped Ge is in the range of\n0.45 K for 6.25 at.% of dopant concentration being in a qualitative agreement\nwith experimentally obtained values."
    },
    {
        "anchor": "Room-temperature 1.54 $\u03bc$m photoluminescence of Er:O$_x$ centers at\n  extremely low concentration in silicon: The demand for single photon sources at $\\lambda~=~1.54~\\mu$m, which follows\nfrom the consistent development of quantum networks based on commercial optical\nfibers, makes Er:O$_x$ centers in Si still a viable resource thanks to the\noptical transition of $Er^{3+}~:~^4I_{13/2}~\\rightarrow~^4I_{15/2}$. Yet, to\ndate, the implementation of such system remains hindered by its extremely low\nemission rate. In this Letter, we explore the room-temperature\nphotoluminescence (PL) at the telecomm wavelength of very low implantation\ndoses of $Er:O_x$ in $Si$. The emitted photons, excited by a $\\lambda~=~792~nm$\nlaser in both large areas and confined dots of diameter down to $5~\\mu$m, are\ncollected by an inverted confocal microscope. The lower-bound number of\ndetectable emission centers within our diffraction-limited illumination spot is\nestimated to be down to about 10$^4$, corresponding to an emission rate per\nindividual ion of about $4~\\times~10^{3}$ photons/s.",
        "positive": "Electronic band structure in pristine and Sulfur-doped Ta$_2$NiSe$_5$: We present an angle-resolved photoemission study of the electronic band\nstructure of the excitonic insulator Ta$_2$NiSe$_5$, as well as its evolution\nupon Sulfur doping. Our experimental data show that while the excitonic\ninsulating phase is still preserved at a Sulfur-doping level of 25$\\%$, such\nphase is heavily suppressed when there is a substantial amount, $\\sim$ 50$\\%$,\nof S-doping at liquid nitrogen temperatures. Moreover, our photon\nenergy-dependent measurements reveal a clear three dimensionality of the\nelectronic structure, both in Ta$_2$NiSe$_5$ and Ta$_2$Ni(Se$_{1-x}$S$_x$)$_5$\n($x=0.25, 0.50$) compounds. This suggests a reduction of electrical and thermal\nconductivities, which might make these compounds less suitable for electronic\ntransport applications."
    },
    {
        "anchor": "Size-dependent ferroelectric-to-paraelectric sliding transformations and\n  antipolar-to-ferroelectric topological phase transitions in binary\n  homobilayers: The recent discovery of ferroelectric behavior in few-layer materials,\naccompanied by the observation of antipolar domains in hexagonal boron nitride\nand transition metal dichalcogenide moir\\'e bilayers, is paving the way for\nrevolutionary advancements in the generation and manipulation of intrinsic\nelectric dipoles through stacking. In addition, these cutting-edge quantum\nmaterials are reshaping our comprehension of phase transitions. Within the\npresent study, we unveil a hitherto unreported size-dependent sliding behavior\nthat marks a significant departure from conventional ferroelectrics. We also\nshed light on thermally induced spontaneous hyperlubric sliding within moir\\'e\nbilayers, which can be used as a signal to distinguish topological phase\ntransitions from an antipolar onto a ferroelectric bilayer. Our findings also\nsuggest that the (topological) pinning of AA nodes in antipolar moir\\'e\nhomobilayers prevents the occurrence of an antipolar-to-paraelectric\ntransformation.",
        "positive": "Ferroelectric effects in PZT: First-principles calculations are performed to investigate alloying and\nferroelectric effects in lead zirconate titanate (PZT) with high Ti\ncomposition. We find that the main effect of alloying in the paraelectric phase\nof PZT is the existence of two sets of B-O bonds, i.e., shorter Ti-O bonds vs.\nlonger Zr-O bonds. On the other hand, ferroelectricity leads to the formation\nof very short covalent Ti-O bonds and to the formation of covalent chains of\nPb-O bonds. The covalency in the ferroelectric phase is mainly induced by an\nenhancement of hybridization between Ti 3d and O 2p, and between Pb 6s and O\n2p. These hybridizations induce a striking decrease of the effective charges\nwhen going from the paraelectric to the ferroelectric phase of PZT."
    },
    {
        "anchor": "Simulation studies of the self-assembly of cone-shaped particles: We systematically investigate the self-assembly of anisotropic cone-shaped\nparticles decorated by ring-like attractive patches. We demonstrate that the\nself-assembled clusters, which arise due to the conical particle's anisotropic\nshape combined with directional attractive interactions, are precise for\ncertain cluster sizes, resulting in a precise packing sequence of clusters of\nincreasing sizes with decreasing cone angles. We thoroughly explore the\ndependence of cluster packing on cone angle and cooling rate, and categorize\nthe resulting structures as stable and metastable clusters. We also discuss the\nimplication of our simulation results in the context of the Israelachvili\npacking rule for surfactants, and a recent geometrical packing analysis on hard\ncones in the limit of large numbers of cones.",
        "positive": "Effect of nonadiabatic spin transfer torque on domain wall resonance\n  frequency and mass: The dynamics of a magnetic domain wall in a semi circular nanowire loop is\nstudied by an analytical model and micromagnetic simulations. We find a damped\nsinusoidal oscillation of the domain wall for small displacement angles around\nits equilibrium position under an external magnetic field in the absence of\ncurrents. By studying the effect of current induced nonadiabatic spin transfer\ntorque on the magnetic domain wall resonance frequency and mass, a red shift is\nfound in the resonance frequency and domain wall mass increases by increasing\nthe ratio of nonadiabatic spin torque to adiabatic contribution above 1."
    },
    {
        "anchor": "Dynamic Interface Rearrangement in LaFeO$_3$ / $n$-SrTiO$_3$\n  Heterojunctions: Thin film synthesis methods developed over the past decades have unlocked\nemergent interface properties ranging from conductivity to ferroelectricity.\nHowever, our attempts to exercise precise control over interfaces are\nconstrained by a limited understanding of growth pathways and kinetics. Here we\ndemonstrate that shuttered molecular beam epitaxy induces rearrangements of\natomic planes at a polar / non-polar junction of LaFeO$_3$ (LFO) /\n$n$-SrTiO$_3$ (STO) depending on the substrate termination. Surface\ncharacterization confirms that substrates with two different (TiO$_2$ and SrO)\nterminations were prepared prior to LFO deposition; however, local electron\nenergy loss spectroscopy measurements of the final heterojunctions show a\npredominantly LaO / TiO$_2$ interfacial junction in both cases. Ab initio\nsimulations suggest that the interfaces can be stabilized by trapping extra\noxygen (in LaO / TiO$_2$) and forming oxygen vacancies (in FeO$_2$ / SrO),\nwhich points to different growth kinetics in each case and may explain the\napparent disappearance of the FeO$_2$ / SrO interface. We conclude that\njudicious control of deposition timescales can be used to modify growth\npathways, opening new avenues to control the structure and properties of\ninterfacial systems.",
        "positive": "Drastically enhanced cation incorporation in the epitaxy of oxides due\n  to formation and evaporation of suboxides from elemental sources: In the molecular beam epitaxy of oxide films, the cation (Sn, Ga) or dopant\n(Sn) incorporation does not follow the vapor pressure of the elemental metal\nsources, but is enhanced by several orders of magnitude for low source\ntemperatures. Using line-of-sight quadrupole mass spectrometry, we identify the\ndominant contribution to the total flux emanating from Sn and Ga sources at\nthese temperatures to be due to the unintentional formation and evaporation of\nthe respective suboxides SnO and Ga$_{2}$O. We quantitatively describe this\nphenomenon by a rate-equation model that takes into account the O background\npressure, the resulting formation of the suboxides via oxidation of the metal\nsource, and their subsequent thermally activated evaporation. As a result, the\ntotal flux composed of the metal and the suboxide fluxes exhibit an\n\\textsf{S}-shape temperature dependence instead of the expected linear one in\nan Arrhenius plot, in excellent agreement with the available experimental data.\nOur model reveals that the thermally activated regimes at low and high\ntemperatures are almost exclusively due to suboxide and metal evaporation,\nrespectively, joined by an intermediate plateau-like regime in which the flux\nis limited by the available amount of O. An important suboxide contribution is\nexpected for all elemental sources whose suboxide exhibits a higher vapor\npressure than the element, such as B, Ga, In, La, Si, Ge, Sn, Sb, Mo, Nb, Ru,\nTa, V, and W. This contribution can play a decisive role in the molecular beam\nepitaxy of oxides, including multicomponent or complex oxides, from elemental\nsources. Finally, our model predicts suboxide-dominated growth in low-pressure\nchemical vapor deposition of Ga$_{2}$O$_{3}$ and In$_{2}$O$_{3}$."
    },
    {
        "anchor": "Near-field electrospinning of conjugated polymer light-emitting\n  nanofibers: The authors report on the realization of ordered arrays of light-emitting\nconjugated polymer nanofibers by near-field electrospinning. The fibers, made\nby poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene], have diameters of\nfew hundreds of nanometers and emission peaked at 560 nm. The observed\nblue-shift compared to the emission from reference films is attributed to\ndifferent polymer packing in the nanostructures. Optical confinement in the\nfibers is also analyzed through self-waveguided emission. These results open\ninteresting perspectives for realizing complex and ordered architectures by\nlight-emitting nanofibers, such as photonic circuits, and for the precise\npositioning and integration of conjugated polymer fibers into light-emitting\ndevices.",
        "positive": "Electromagnon in Y-type hexaferrite BaSrCoZnFe$_{11}$AlO$_{22}$: We investigated static and dynamic magnetoelectric properties of single\ncrystalline BaSrCoZnFe$_{11}$AlO$_{22}$ which is a room-temperature\nmultiferroic with Y-type hexaferrite crystal structure. Below $300\\,\\rm K$, a\npurely electric-dipole-active electromagnon at $\\approx 1.2\\,\\rm THz$ with the\nelectric polarization oscillating along the hexagonal axis was observed by THz\nand Raman spectroscopies. We investigated the behavior of the electromagnon\nwith applied DC magnetic field and linked its properties to static measurements\nof the magnetic structure. Our analytical calculations determined selection\nrules for electromagnons activated by the magnetostriction mechanism in various\nmagnetic structures of Y-type hexaferrite. Comparison with our experiment\nsupports that the electromagnon is indeed activated by the magnetostriction\nmechanism involving spin vibrations along the hexagonal axis."
    },
    {
        "anchor": "Structural transformations driven by local disorder at interfaces: Despite the fundamental importance of solid-solid transformations in many\ntechnologies, the microscopic mechanisms remain poorly understood. Here, we\nexplore the atomistic mechanisms at the migrating interface during solid-solid\nphase transformations between the topologically closed-packed A15 and\nbody-centred cubic phase in tungsten. The high energy barriers and slow\ndynamics associated with this transformation require the application of\nenhanced molecular sampling approaches. To this end, we performed metadynamics\nsimulations in combination with a path collective variable derived from a\nmachine learning classification of local structural environments, which allows\nthe system to freely sample the complex interface structure. A disordered\nregion of varying width forming at the migrating interface is identified as a\nkey physical descriptor of the transformation mechanisms, facilitating the\natomic shuffling and rearrangement necessary for structural transformations.\nFurthermore, this can directly be linked to the differences in interface\nmobility for distinct orientation relationships as well as the formation of\ninterfacial ledges during the migration along low-mobility directions.",
        "positive": "Sodium: a charge-transfer insulator at high pressures: By means of first-principles methods we analyze the optical response of\ntransparent dense sodium as a function of applied pressure. We discover an\nunusual kind of charge-transfer exciton that proceeds from the interstitial\ndistribution of valence electrons repelled away from the ionic cores by the\nCoulomb interaction and the Pauli repulsion. The predicted absorption spectrum\nshows a strong anisotropy with light polarization that just at pressures above\nthe metal-insulator transition manifests as sodium being optically transparent\nin one direction but reflective in the other. This result provides a key\ninformation about the crystal structure of transparent sodium, a new\nunconventional inorganic electride."
    },
    {
        "anchor": "Simulations of multivariant Si I to Si II phase transformation in\n  polycrystalline silicon with finite-strain scale-free phase-field approach: Scale-free phase-field approach (PFA) at large strains and corresponding\nfinite element method (FEM) simulations for multivariant martensitic phase\ntransformation (PT) from cubic Si I to tetragonal Si II in a polycrystalline\naggregate are presented. Important features of the model are large and very\nanisotropic transformation strain tensor $\\varepsilon_{t}=\\{0.1753;0.1753;\n-0.447\\}$ and stress-tensor dependent athermal dissipative threshold for PT,\nwhich produce essential challenges for computations. 3D polycrystals with 55\nand 910 stochastically oriented grains are subjected to uniaxial strain- and\nstress-controlled loadings under periodic boundary conditions and zero averaged\nlateral strains. Coupled evolution of discrete martensitic microstructure,\nvolume fractions of martensitic variants and Si II, stress and transformation\nstrain tensors, and texture are presented and analyzed. Macroscopic variables\neffectively representing multivariant transformational behavior are introduced.\nMacroscopic stress-strain and transformational behavior for 55 and 910 grains\nare close (less than 10% difference). This allows the determination of\nmacroscopic constitutive equations by treating aggregate with a small number of\ngrains. Large transformation strains and grain boundaries lead to huge internal\nstresses of tens GPa, which affect microstructure evolution and macroscopic\nbehavior. In contrast to a single crystal, the local mechanical instabilities\ndue to PT and negative local tangent modulus are stabilized at the macroscale\nby arresting/slowing the growth of Si II regions by the grain boundaries and\ngenerating the internal back stresses. This leads to increasing stress during\nPT. The developed methodology can be used for studying similar PTs with large\ntransformation strains and for further development by including plastic strain\nand strain-induced PTs.",
        "positive": "Dislocation avalanches from strain-controlled loading: A discrete\n  dislocation dynamics study: We study strain-controlled plastic deformation of crystalline solids via\ntwo-dimensional discrete dislocation dynamics simulations. To this end, we\ncharacterize the average stress-strain curves as well as the statistical\nproperties of strain bursts and the related stress drops as a function of the\nimposed strain rate and the stiffness of the specimen-machine system. The\ndislocation system exhibits strain rate sensitivity such that a larger imposed\nstrain rate results in a higher average stress at a given strain. In the limit\nof small strain rate and driving spring stiffness, the sizes and durations of\nthe dislocation avalanches are power-law distributed up to a cutoff scale, and\nexhibit temporally asymmetric average shapes. We discuss the dependence of the\nresults on the driving parameters, and compare our results to those from\nprevious simulations where quasistatic stress-controlled loading was used."
    },
    {
        "anchor": "Crystalline and Electronic Structures of Molecular Solid C$_{50}$Cl$%\n  _{10}$: First-Principles Calculation: A molecular solid C$_{50}$Cl$_{10}$ with possible crystalline structures,\nincluding the hexagonal-close-packed (hcp) phase, the face-centered cubic (fcc)\nphase, and a hexagonal monolayer, is predicted in terms of first-principles\ncalculation within the density functional theory. The stable structures are\ndetermined from the total-energy calculations, where the hcp phase is uncovered\nmore stable than the fcc phase and the hexagonal monolayer in energy per\nmolecule. The energy bands and density of states for hcp and fcc\nC$_{50}$Cl$_{10}$ are presented. The results show that C$_{50}$Cl% $_{10}$\nmolecules can form either a hcp or fcc indirect-gap band insulator or an\ninsulating hexagonal monolayer.",
        "positive": "Does thiosemicarbazide lead nitrate (TSLN) crystal exist?: The authors of a recent paper (Optik 125 (2014) 2022-2025) claim to have\ngrown a so called thiosemicarbazide lead nitrate (TSLN) crystal by the slow\nevaporation method. In this comment we prove that TSLN is actually\nthiosemicarbazide."
    },
    {
        "anchor": "Electrical detection of microwave assisted magnetization reversal by\n  spin pumping: Microwave assisted magnetization reversal has been investigated in a bilayer\nsystem of Pt/ferromagnet by detecting a change in the polarity of the spin\npumping signal. The reversal process is studied in two material systems,\nPt/CoFeB and Pt/NiFe, for different aspect ratios. The onset of the switching\nbehavior is indicated by a sharp transition in the spin pumping voltage. At a\nthreshold value of the external field, the switching process changes from\npartial to full reversal with increasing microwave power. The proposed method\nprovides a simple way to detect microwave assisted magnetization reversal.",
        "positive": "Canonical-ensemble extended Lagrangian Born-Oppenheimer molecular\n  dynamics for the linear scaling density functional theory: We discuss the development and implementation of a constant temperature (NVT)\nmolecular dynamics scheme that combines the Nos\\'e-Hoover chain thermostat with\nthe extended Lagrangian Born-Oppenheimer molecular dynamics (BOMD) scheme,\nusing a linear scaling density functional theory (DFT) approach. An integration\nscheme for this canonical-ensemble extended Lagrangian BOMD is developed and\ndiscussed in the context of the Liouville operator formulation. Linear scaling\nDFT canonical-ensemble extended Lagrangian BOMD simulations are tested on bulk\nsilicon and silicon carbide systems to evaluate our integration scheme. The\nresults show that the conserved quantity remains stable with no systematic\ndrift even in the presence of the thermostat."
    },
    {
        "anchor": "Room-Temperature Intrinsic and Extrinsic Damping in Polycrystalline Fe\n  Thin Films: We examine room-temperature magnetic relaxation in polycrystalline Fe films.\nOut-of-plane ferromagnetic resonance (FMR) measurements reveal Gilbert damping\nparameters of $\\approx$ 0.0024 for Fe films with thicknesses of 4-25 nm,\nregardless of their microstructural properties. The remarkable invariance with\nfilm microstructure strongly suggests that intrinsic Gilbert damping in\npolycrystalline metals at room temperature is a local property of nanoscale\ncrystal grains, with limited impact from grain boundaries and film roughness.\nBy contrast, the in-plane FMR linewidths of the Fe films exhibit distinct\nnonlinear frequency dependences, indicating the presence of strong extrinsic\ndamping. To fit our in-plane FMR data, we have used a grain-to-grain two-magnon\nscattering model with two types of correlation functions aimed at describing\nthe spatial distribution of inhomogeneities in the film. However, neither of\nthe two correlation functions is able to reproduce the experimental data\nquantitatively with physically reasonable parameters. Our findings advance the\nfundamental understanding of intrinsic Gilbert damping in structurally\ndisordered films, while demonstrating the need for a deeper examination of how\nmicrostructural disorder governs extrinsic damping.",
        "positive": "Memristive phase switching in two-dimensional crystals: Scaling down materials to an atomic-layer level produces rich physical and\nchemical properties as exemplified in various two-dimensional (2D) crystals\nextending from graphene, transition metal dichalcogenides to black phosphorous.\nThis is caused by the dramatic modification of electronic band structures. In\nsuch reduced dimensions, the electron correlation effects are also expected to\nbe significantly changed from bulk systems. However, there are few attempts to\nrealize novel phenomena in correlated 2D crystals. Here, we report memristive\nphase switching in nano-thick crystals of 1T-type tantalum disulfide (1T-TaS2),\na first-order phase transition system. The ordering kinetics of the phase\ntransition was revealed to become extremely slow as the thickness is reduced,\nresulting in an emergence of metastable states. Furthermore, we realized the\nunprecedented memristive switching to multi-step non-volatile states by\napplying in-plane electric field. The reduction of thickness is essential to\nachieve such non-volatile electrical switching behavior. The thinning-induced\nslow kinetics possibly makes the various metastable states robust and\nconsequently realizes the non-volatile memory operation. The present result\nindicates that 2D crystal with correlated electrons is a novel nano-system to\nexplore and functionalize multiple metastable states which are inaccessible in\nits bulk form."
    },
    {
        "anchor": "Orbital-driven Rashba effect in a binary honeycomb monolayer AgTe: The Rashba effect is fundamental to the physics of two-dimensional electron\nsystems and underlies a variety of spintronic phenomena. It has been proposed\nthat the formation of Rashba-type spin splittings originates microscopically\nfrom the existence of orbital angular momentum (OAM) in the Bloch wave\nfunctions. Here, we present detailed experimental evidence for this OAM-based\norigin of the Rashba effect by angle-resolved photoemission (ARPES) and\ntwo-photon photoemission (2PPE) experiments for a monolayer AgTe on Ag(111).\nUsing quantitative low-energy electron diffraction (LEED) analysis we determine\nthe structural parameters and the stacking of the honeycomb overlayer with\npicometer precision. Based on an orbital-symmetry analysis in ARPES and\nsupported by first-principles calculations, we unequivocally relate the\npresence and absence of Rashba-type spin splittings in different bands of AgTe\nto the existence of OAM.",
        "positive": "Unidirectional spin density wave state in metallic (Sr1-xLax)2IrO4: Materials that exhibit both strong spin orbit coupling and electron\ncorrelation effects are predicted to host numerous new electronic states. One\nprominent example is the Jeff =1/2 Mott state in Sr2IrO4, where introducing\ncarriers is predicted to manifest high temperature superconductivity analogous\nto the S=1/2 Mott state of La2CuO4. While bulk superconductivity currently\nremains elusive, anomalous quasi-particle behaviors paralleling those in the\ncuprates such as pseudogap formation and the formation of a d-wave gap are\nobserved upon electron-doping Sr2IrO4. Here we establish a magnetic parallel\nbetween electron-doped Sr2IrO4 and hole-doped La2CuO4 by unveiling a spin\ndensity wave state in electron-doped Sr2IrO4. Our magnetic resonant x-ray\nscattering data reveal the presence of an incommensurate magnetic state\nreminiscent of the diagonal spin density wave state observed in the monolayer\ncuprate (La1-xSrx)2CuO4. This link supports the conjecture that the quenched\nMott phases in electron-doped Sr2IrO4 and hole-doped La2CuO4 support common\ncompeting electronic phases."
    },
    {
        "anchor": "The Fermi surfaces of Metallic Alloys and the Oscillatory Magnetic\n  Coupling between Magnetic Layers separated by such Alloy Spacers: We review the theory of oscillatory magnetic coupling in Metallic Multilayers\nacross alloy spacers. We illustrate the relationship between the frequencies of\nthe oscillations and the extremal caliper vectors of the Fermi surface of the\nspacer by explicit calculations for Cu$_{(1-x)}$Ni$_x$, Cr$_{(1-x)}$V$_x$ and\nCr$_{(1-x)}$Mo$_x$ alloys. We argue the measurement of the frequencies of such\noscillations can be an extremely useful and cheap probe of the Fermi surface of\nrandom alloys.",
        "positive": "Ground state structure of polymeric carbon monoxide with high energy\n  density: Crystal structure prediction methods and first-principles calculations have\nbeen used to explore low-energy structures of carbon monoxide (CO). Contrary to\nthe standard wisdom, the most stable structure of CO at ambient pressure was\nfound to be a polymeric structure of Pna21 symmetry rather than a molecular\nsolid. This phase is formed from six-membered (4 Carbon + 2 Oxygen) rings\nconnected by C=C double bonds with two double-bonded oxygen atoms attached to\neach ring. Interestingly, the polymeric Pna21 phase of CO has a much higher\nenergy density than trinitrotoluene (TNT). On compression to about 7 GPa, Pna21\nis found to transform into another chain-like phase of Cc symmetry which has\nsimilar ring units to Pna21. On compression to 100 GPa it is energetically\nfavorable for CO to polymerize to form a single-bonded Cmcm phase from another\nstructure of Cmca symmetry composed of units similar to those found in the\nsingle-bonded I212121 structure. Thermodynamic stability of these structures\nwas verified using calculations with different density functionals, including\nhybrid and van der Waals corrected functionals."
    },
    {
        "anchor": "Mechanical Metastructures of Triple Periodic Carbon Clathrates: Clathrates are lightweight, cage-like, fully-sp3 three dimensional (3D)\nstructures that are experimentally-available for several host elements of the\nIV group. However, carbon clathrates are as yet hypothetical structures.\nHerein, the mechanical properties of Type-I-C46 Type-II-C34 and Type-H-C34\ncarbon clathrates are explored by first-principles calculations. It is revealed\nthat those carbon clathrates show distinct anisotropic patterns in ideal\ntensile/shear strengths and critical tensile/shear strains, with maximum ideal\ntensile strength of Type-I carbon clathrate that is superior over that of\ndiamond in <111> direction. However, it is identified isotropy in shear Youngs\nmodulus, and in terms of tensile/shear Youngs moduli, they are sorted as Type-I\n> Type-II > Type-H carbon clathrates. There are distinct critical load-bearing\nbond configurations that explain their distinct mechanical behaviors. Moreover,\nthose carbon clathrates are intrinsically indirect semiconductors, and their\nelectronic properties can be greatly dictated by mechanical strain. Carbon\nclathrates can be potentially utilized as lightweight technically robust\nengineering metastructures and in electromechanical devices.",
        "positive": "Cluster glass magnetism in the phase-separated Nd2/3Ca1/3MnO3 perovskite: A detailed study of the low-temperature magnetic state and the relaxation in\nthe phase-separated colossal magnetoresistance Nd2/3Ca1/3MnO3 perovskite has\nbeen carried out. Clear experimental evidence of the cluster-glass magnetic\nbehavior of this compound has been revealed. Well defined maxima in the\nin-phase linear ac susceptibility $\\chi ^{/}(T)$ were observed, indicative of\nthe magnetic glass transition at $T_{g}$ = 60 K. Strongly divergent\nzero-field-cooled and field-cooled static magnetizations and frequency\ndependent ac susceptibility are evident of the glassy-like magnetic state of\nthe compound at low temperatures. The frequency dependence of the cusp\ntemperature Tmax of the $\\chi ^{/}(T)$ susceptibility was found to follow the\ncritical slowing down mechanism. The Cole-Cole analysis of the dynamic\nsusceptibility at low temperature has shown extremely broad distribution of\nrelaxation times, indicating that spins are frozen at \"macroscopic\" time scale.\nSlow relaxation in the zero-field-cooled magnetization has been experimentally\nrevealed. The obtained results do not agree with a canonical spin-glass state\nand indicate a cluster glass magnetic state of the compound below $T_{g}$,\nassociated with its antiferromagnetic-ferromagnetic nano-phase segregated\nstate. It was found that the relaxation mechanisms below the cluster glass\nfreezing temperature $T_{g}$ and above it are strongly different. Magnetic\nfield up to about $\\mu_{0}$H = 0.4 T suppresses the glassy magnetic state of\nthe compound."
    },
    {
        "anchor": "Infrared luminescence in Bi-doped Ge-S and As-Ge-S chalcogenide glasses\n  and fibers: Experimental and theoretical studies of spectral properties of chalcogenide\nGe-S and As-Ge-S glasses and fibers are performed. A broad infrared (IR)\nluminescence band which covers the 1.2-2.3~$\\mu$m range with a lifetime about\n6~$\\mu$s is discovered. Similar luminescence is also present in optical fibers\ndrawn from these glasses. Arsenic addition to Ge-S glass significantly enhances\nboth its resistance to crystallization and the intensity of the luminescence.\nComputer modeling of Bi-related centers shows that interstitial Bi$^+$ ions\nadjacent to negatively charged S vacancies are most likely responsible for the\nIR luminescence.",
        "positive": "Acoustic metamaterial exhibiting four different sign combinations of\n  density and modulus: We fabricated a double negative acoustic metamaterial which consisted of\nHelmholtz resonators and membranes. Experimental data on the transmission and\ndispersion relation are presented. The system exhibits three frequencies where\nthe acoustic state makes sharp transitions from density negative ({\\rho} -NG)\nto double negative (DNG), modulus negative (B-NG), and double positive (DPS) in\nsequence with the frequency. We observed a wide range of negative refractive\nindex from -0.06 to -3.7 relative to air, which will allow for new acoustic\ntransformation techniques."
    },
    {
        "anchor": "Unit cell of graphene on Ru(0001): a 25 x 25 supercell with 1250 carbon\n  atoms: The structure of a single layer of graphene on Ru(0001) has been studied\nusing surface x-ray diffraction. A surprising superstructure has been\ndetermined, whereby 25 x 25 graphene unit cells lie on 23 x 23 unit cells of\nRu. Each supercell contains 2 x 2 crystallographically inequivalent subcells\ncaused by corrugation. Strong intensity oscillations in the superstructure rods\ndemonstrate that the Ru substrate is also significantly corrugated down to\nseveral monolayers, and that the bonding between graphene and Ru is strong and\ncannot be caused by van der Waals bonds. Charge transfer from the Ru substrate\nto the graphene expands and weakens the C-C bonds, which helps accommodate the\nin-plane tensile stress. The elucidation of this superstructure provides\nimportant information in the potential application of graphene as a template\nfor nanocluster arrays.",
        "positive": "Electrical Relaxation and Transport in 0.5Cs2O- 0.5Li2O-3B2O3 Glasses: The frequency and temperature dependence of the dielectric constant and the\nelectrical conductivity of the transparent glasses in the composition\n0.5Cs2O-0.5Li2O-3B2O3 (CLBO) were investigated in the 100 Hz - 10 MHz frequency\nrange. The dielectric constant for the as-quenched glass increased with\nincreasing temperature, exhibiting anomalies in the vicinity of the glass\ntransition and crystallization temperatures. The temperature coefficient of\ndielectric constant was estimated (35 \\pm 2 ppm.K-1) using Havinga's formula.\nThe dielectric loss at 313 K is 0.005 \\pm 0.0005 at all the frequencies\nunderstudy. The activation energy associated with the electrical relaxation\ndetermined from the electric modulus spectra was found to be 1.73 \\pm 0.05 eV,\nclose to that of the activation energy obtained for DC conductivity (1.6 \\pm\n0.06 eV). The frequency dependent electrical conductivity was analyzed using\nJonscher's power law. The combination of these dielectric characteristics\nsuggests that these are good candidates for electrical energy storage device\napplications."
    },
    {
        "anchor": "Topological surface currents accessed through reversible hydrogenation\n  of the three-dimensional bulk: Hydrogen, the smallest and most abundant element in nature, can be\nefficiently incorporated within a solid and drastically modify its electronic\nstate - it has been known to induce novel magnetoelectric effects in complex\nperovskites and modulate insulator-to-metal transition in a correlated Mott\noxide. Here we demonstrate that hydrogenation resolves an outstanding challenge\nin chalcogenide classes of three-dimensional (3D) topological insulators and\nmagnets - the control of intrinsic bulk conduction that denies access to\nquantum surface transport. With electrons donated by a reversible binding of H+\nions to Te(Se) chalcogens, carrier densities are easily changed by over 10^20\ncm^-3, allowing tuning the Fermi level into the bulk bandgap to enter\nsurface/edge current channels. The hydrogen-tuned topological materials are\nstable at room temperature and tunable disregarding bulk size, opening a\nbreadth of platforms for harnessing emergent topological states.",
        "positive": "Electronic band structure of ultimately thin silicon oxide on Ru(0001): Silicon oxide can be formed in a crystalline form, when prepared on a\nmetallic substrate. It is a candidate support catalyst and possibly the\nultimately-thin version of a dielectric host material for two-dimensional\nmaterials (2D) and heterostructures. We determine the atomic structure and\nchemical bonding of the ultimately thin version of the oxide, epitaxially grown\non Ru(0001). In particular, we establish the existence of two sub-lattices\ndefined by metal-oxygen-silicon bridges involving inequivalent substrate sites.\nWe further discover four electronic bands below Fermi level, at high binding\nenergies, two of them forming a Dirac cone at K point, and two others forming\nsemi-flat bands. While the latter two correspond to hybridized states between\nthe oxide and the metal, the former relate to the topmost silicon-oxygen plane,\nwhich is not directly coupled to the substrate. Our analysis is based on high\nresolution X-ray photoelectron spectroscopy, angle-resolved photoemission\nspectroscopy, scanning tunneling microscopy, and density functional theory\ncalculations."
    },
    {
        "anchor": "Charge carrier coupling to the soft phonon mode in a ferroelectric\n  semiconductor: Many crystalline solids possess strongly anharmonic soft phonon modes\ncharacterized by diminishing frequency as temperature approaches a critical\npoint associated with a symmetry breaking phase transition. While electron-soft\nphonon coupling can introduce unique scattering channels for charge carriers in\nferroelectrics, recent studies on the non-ferroelectric lead halide perovskites\nhave also suggested the central role of anharmonic phonons bearing resemblance\nto soft modes in charge carrier screening. Here we apply coherent phonon\nspectroscopy to directly study electron coupling to the soft transverse optical\n(TO) phonon mode in a ferroelectric semiconductor SbSI. Photo-generated charge\ncarriers in SbSI are found to be exceptionally long lived and are associated\nwith a transient electro-optical effect that can be explained by interactions\nbetween charge carriers and thermally stimulated soft-phonon excitations. These\nresults provide strong evidence for the role of electron-soft phonon coupling\nin the efficient screening of charge carriers and in reducing charge\nrecombination rates, both desirable properties for optoelectronics.",
        "positive": "Wannier-function approach to spin excitations in solids: We present a computational scheme to study spin excitations in magnetic\nmaterials from first principles. The central quantity is the transverse spin\nsusceptibility, from which the complete excitation spectrum, including\nsingle-particle spin-flip Stoner excitations and collective spin-wave modes,\ncan be obtained. The susceptibility is derived from many-body perturbation\ntheory and includes dynamic correlation through a summation over ladder\ndiagrams that describe the coupling of electrons and holes with opposite spins.\nIn contrast to earlier studies, we do not use a model potential with adjustable\nparameters for the electron-hole interaction but employ the random-phase\napproximation. To reduce the numerical cost for the calculation of the\nfour-point scattering matrix we perform a projection onto maximally localized\nWannier functions, which allows us to truncate the matrix efficiently by\nexploiting the short spatial range of electronic correlation in the partially\nfilled d or f orbitals. Our implementation is based on the FLAPW method.\nStarting from a ground-state calculation within the LSDA, we first analyze the\nmatrix elements of the screened Coulomb potential in the Wannier basis for the\n3d transition-metal series. In particular, we discuss the differences between a\nconstrained nonmagnetic and a proper spin-polarized treatment for the\nferromagnets Fe, Co, and Ni. The spectrum of single-particle and collective\nspin excitations in fcc Ni is then studied in detail. The calculated spin-wave\ndispersion is in good overall agreement with experimental data and contains\nboth an acoustic and an optical branch for intermediate wave vectors along the\n[100] direction. In addition, we find evidence for a similar double-peak\nstructure in the spectral function along the [111] direction."
    },
    {
        "anchor": "Phonon effects on x-ray absorption and nuclear magnetic resonance\n  spectroscopies: In material sciences, spectroscopic approaches combining ab initio\ncalculations with experiments are commonly used to accurately analyze the\nexperimental spectral data. Most state-of-the-art first-principle calculations\nare usually performed assuming an equilibrium static lattice. Yet, nuclear\nmotion affects spectra even when reduced to the zero-point motion at 0 K. We\npropose a framework based on Density-Functional Theory that includes quantum\nthermal fluctuations in theoretical X- ray Absorption Near-Edge Structure\n(XANES) and solid-state Nuclear Magnetic Resonance (NMR) spectroscopies and\nallows to well describe temperature effects observed experimentally. Within the\nBorn-Oppenheimer and quasi-harmonic approximations, we incorporate the nuclear\nmotion by generating several non-equilibrium configurations from the dynamical\nmatrix. The averaged calculated XANES and NMR spectral data have been compared\nto experiments in MgO, proof-of-principle compound. The good agreement obtained\nbetween experiments and calculations validates the developed approach, which\nsuggests that calculating the XANES spectra at finite temperature by averaging\nindividual non-equilibrium configurations is a suitable approximation. This\nstudy high- lights the relevance of phonon renormalization and the relative\ncontributions of thermal expansion and nuclear dynamics on NMR and XANES\nspectra on a wide range of temperatures.",
        "positive": "Simultaneous rheo-electric measurements of strongly conductive complex\n  fluids: We introduce a novel apparatus designed for stress-controlled rheometers to\nperform simultaneous rheological and electrical measurements on strongly\nconductive complex fluids under shear. By means of a non-toxic liquid metal at\nroom temperature, the electrical connection to the rotating shaft is completed\nwith minimal additional mechanical friction, allowing for simultaneous stress\nmeasurements as low as 1 Pa. We use the capabilities of this design to perform\nan extensive set of rheo-electric experiments on gels formulated from\nattractive carbon black particles, at concentrations ranging from 4 to 15% wt.\nFirst, experiments on gels at rest prepared with different shear history show a\nrobust power-law scaling between the elastic modulus $G'_0$ and the\nconductivity $\\sigma_0$ of the gels, i.e. $G'_0 \\sim \\sigma_0^\\alpha$, with\n$\\alpha =1.65 \\pm 0.04$ independently of the gel concentration. Second,\nconductivity measurements performed simultaneously with creep experiments\nreveal for the first time that plastic events take place in the bulk while the\nshear rate decreases as a weak power law of time in the early stage of the\nexperiment. The subsequent evolution of the conductivity and shear rate allows\nus to propose a local yielding scenario that is in agreement with previous\nvelocimetry measurements. Finally, we determine the constitutive rheological\nand electrical behavior of carbon black gels. Corrections first introduced for\nmechanical measurements are carefully extended to electrical measurements to\naccurately distinguish between bulk and surface contributions to the\nconductivity. As an illustrative example, we examine the constitutive\nrheo-electric properties of five carbon black gels of different grades, and\ndemonstrate the relevance of the novel rheo-electric apparatus as a versatile\ncharacterization tool for strongly conductive complex fluids and their\napplications."
    },
    {
        "anchor": "Quenched lattice fluctuations in optically driven SrTiO3: Many functionally relevant ferroic phenomena in quantum materials can be\nmanipulated by driving the lattice coherently with optical and terahertz\npulses. New physical phenomena and non-equilibrium phases that have no\nequilibrium counterpart have been discovered following these protocols. The\nunderlying structural dynamics has been mostly studied by recording the average\natomic position along dynamical structural coordinates with elastic scattering\nmethods. However, crystal lattice fluctuations, which are known to influence\nphase transitions in equilibrium, are also expected to determine these dynamics\nbut have rarely been explored. Here, we study the driven dynamics of the\nquantum paraelectric SrTiO3, in which mid-infrared drives have been shown to\ninduce a metastable ferroelectric state. Crucial in these physics is the\ncompetition between the polar instability and antiferrodistortive rotations,\nwhich in equilibrium frustrate the formation of long-range ferroelectricity. We\nmake use of high intensity mid-infrared optical pulses to resonantly drive a\nTi-O stretching mode at 17 THz, and we measure the resulting change in lattice\nfluctuations using time-resolved x-ray diffuse scattering at a free electron\nlaser. After a prompt increase, we observe a long-lived quench in R-point\nantiferrodistortive lattice fluctuations. The enhancement and reduction in\nlattice fluctuations are explained theoretically by considering fourth-order\nnonlinear phononic interactions and third-order coupling to the driven optical\nphonon and to lattice strain, respectively. These observations provide a number\nof new and testable hypotheses for the physics of light-induced\nferroelectricity.",
        "positive": "Compressing and forecasting atomic material simulations with descriptors: Atomic simulations of material microstructure require significant resources\nto generate, store and analyze. Here, atomic descriptor functions are proposed\nas a general latent space to compress atomic microstructure, ideal for use in\nlarge-scale simulations. Descriptors can regress a broad range of properties,\nincluding character-dependent dislocation densities, stress states or radial\ndistribution functions. A vector autoregressive model can generate trajectories\nover yield points, resample from new initial conditions and forecast trajectory\nfutures. A forecast confidence, essential for practical application, is derived\nby propagating forecasts through the Mahalanobis outlier distance, providing a\npowerful tool to assess coarse-grained models. Application to nanoparticles and\nyielding of dislocation networks confirms low uncertainty forecasts are\naccurate and resampling allows for the propagation of smooth microstructure\ndistributions. Yielding is associated with a collapse in the intrinsic\ndimension of the descriptor manifold, which is discussed in relation to the\nyield surface."
    },
    {
        "anchor": "Massively parallel atomistic simulation of ultrafast thermal spin\n  dynamics of a permalloy vortex: Ultrafast magnetization dynamics probes the most fundamental properties of\nmagnetic materials, exploring questions about the fundamental interactions\nresponsible for magnetic phenomena. Thermal effects are known to be extremely\nimportant for laser-induced dynamics in metallic systems, but the dynamics of\ntopological magnetic structures are little understood. Here we apply a\nmassively parallel atomistic spin dynamics simulation to study the response of\na permalloy vortex to a 50 fs laser pulse. We find that macroscopically the\nshort timescale dynamics are indistinguishable from the bulk, but that strong\nedge spin waves lead to a complex time evolution of the magnetic structure and\nlong-lived oscillations on the nanosecond timescale. In the near future such\nsimulations will provide unprecedented insight into the dynamics of magnetic\nmaterials and devices beyond the approximations of continuum micromagnetics.",
        "positive": "Band-edge problem in the theoretical determination of defect energy\n  levels: the O vacancy in ZnO as a benchmark case: Calculations of formation energies and charge transition levels of defects\nroutinely rely on density functional theory (DFT) for describing the electronic\nstructure. Since bulk band gaps of semiconductors and insulators are not well\ndescribed in semilocal approximations to DFT, band-gap correction schemes or\nadvanced theoretical models which properly describe band gaps need to be\nemployed. However, it has become apparent that different methods that reproduce\nthe experimental band gap can yield substantially different results regarding\ncharge transition levels of point defects. We investigate this problem in the\ncase of the (+2/0) charge transition level of the O vacancy in ZnO, which has\nattracted considerable attention as a benchmark case. For this purpose, we\nfirst perform calculations based on non-screened hybrid density functionals,\nand then compare our results with those of other methods. While our results\nagree very well with those obtained with screened hybrid functionals, they are\nstrikingly different compared to those obtained with other band-gap corrected\nschemes. Nevertheless, we show that all the different methods agree well with\neach other and with our calculations when a suitable alignment procedure is\nadopted. The proposed procedure consists in aligning the electron band\nstructure through an external potential, such as the vacuum level. When the\nelectron densities are well reproduced, this procedure is equivalent to an\nalignment through the average electrostatic potential in a calculation subject\nto periodic boundary conditions. We stress that, in order to give accurate\ndefect levels, a theoretical scheme is required to yield not only band gaps in\nagreement with experiment, but also band edges correctly positioned with\nrespect to such a reference potential."
    },
    {
        "anchor": "Electron-electron correlation in graphite: The full three dimensional dispersion of the pi-bands, Fermi velocities and\neffective masses are measured with angle resolved photoemission spectroscopy\nand compared to first-principles calculations. The band structure by\ndensity-functional theory strongly underestimates the slope of the bands and\nthe trigonal warping effect. Including electron-electron calculation on the\nlevel of the GW approximation, however, yields remarkable agreement in the\nvicinity of the Fermi level. This demonstrates the breakdown of the independent\nelectron picture in semi-metallic graphite and points towards a pronounced role\nof electron correlation for the interpretation of transport experiments and\ndouble-resonant Raman scattering for a wide range of carbon based materials.",
        "positive": "Photon induced near-field electron microscopy from nanostructured\n  metallic films and membranes: We investigate - both experimentally and theoretically - the inelastic\ninteraction between fast electrons and the electromagnetic field scattered by\nmetallic apertures and nanostructures on dielectric membranes using photon\ninduced near-field electron microscopy. The experiments - performed in a high\nbrightness ultrafast transmission electron microscope - on gold apertures on\nsilicon nitride membranes reveal strong modulations of the electron-light\ncoupling strength. We demonstrates that this effect results from the combined\naction of the electric field scattered by the aperture edges and the reflection\nand transmission of the incident wave by the dielectric membrane. Moreover,\nwhen a nanostructure is added inside the metallic aperture, the new scattered\nfield interferes with the previous contributions, thus imprinting the optical\nresponse of the nanostructure in additional modulations of the electron-light\ncoupling strength. Using systematic electrodynamics simulations based on the\nGreen dyadic method, we quantitatively analyze these different contributions to\nthe electron-light coupling and propose further applications."
    },
    {
        "anchor": "Exploring T-carbon for Energy Applications: Seeking for next-generation energy sources that are economic, sustainable\n(renewable), clean (environment-friendly), and abundant in earth is crucial\nwhen facing the challenges of energy crisis. There have been numerous studies\nexploring the possibility of carbon based materials to be utilized in future\nenergy applications. In this paper, we introduce T-carbon, which is a\ntheoretically predicted but recently experimentally synthesized carbon\nallotrope, as a promising material for next-generation energy applications. It\nis shown that T-carbon can be potentially used in thermoelectrics, hydrogen\nstorage, lithium ion batteries, \\emph{etc}. The challenges, opportunities, and\npossible directions for future studies of energy applications of T-carbon are\nalso addressed. With the development of more environment-friendly technologies,\nthe promising applications of T-carbon in energy fields would not only produce\nscientifically significant impact in related fields but also lead to a number\nof industrial and technical applications.",
        "positive": "Strain-Control of the magnetic anisotropy in (Ga,Mn)(As,P) ferromagnetic\n  semiconductor layers: A small fraction of phosphorus (up to 10 %) was incorporated in ferromagnetic\n(Ga,Mn)As epilayers grown on a GaAs substrate. P incorporation allows reducing\nthe epitaxial strain or even change its sign, resulting in strong modifications\nof the magnetic anisotropy. In particular a reorientation of the easy axis\ntoward the growth direction is observed for high P concentration. It offers an\ninteresting alternative to the metamorphic approach, in particular for\nmagnetization reversal experiments where epitaxial defects stongly affect the\ndomain wall propagation."
    },
    {
        "anchor": "Sub-nanometer free electrons with topological charge: The holographic mask technique is used to create freely moving electrons with\nquantized angular momentum. With electron optical elements they can be focused\nto vortices with diameters below the nanometer range. The understanding of\nthese vortex beams is important for many applications. Here we present a theory\nof focused free electron vortices. The agreement with experimental data is\nexcellent. As an immediate application, fundamental experimental parameters\nlike spherical aberration and partial coherence are determined.",
        "positive": "Theoretical analysis of zirconium oxynitride/water interface using\n  neural network potential: Zr oxides and oxynitrides are promising candidates to replace precious metal\ncathodes in polymer electrolyte fuel cells. Oxygen reduction reaction activity\nin this class of materials has been correlated with the amount of oxygen\nvacancies, but a microscopic understanding of this correlation is still\nlacking. To address this, we simulate a defective Zr$_7$O$_8$N$_4$/H$_2$O\ninterface model and compare it with a pristine ZrO$_2$/H$_2$O interface model.\nFirst, ab initio replica exchange Monte Carlo sampling was performed to\ndetermine defect segregation at the surface in the oxynitride slab model, then\nmolecular dynamics accelerated by neural network potentials was used to perform\n1000 of 500 ps-long simulations to attain sufficient statistical accuracy of\nthe solid/liquid interface structure. The presence of oxygen vacancies on the\nsurface was found to clearly modify the local adsorption structure: water\nmolecules were found to adsorb preferentially on Zr atoms surrounding oxygen\nvacancies, but not on the oxygen vacancies themselves. The fact that oxygen\nvacancy sites are free from poisoning by water molecules may explain the\nactivity enhancement in defective systems. The layering of water molecules was\nalso modified considerably, which should influence the proton and O$_2$\ntransport near the interfaces which is another parameter that determines the\noverall activity."
    },
    {
        "anchor": "Nambu-Goldstone modes and diffuse deformations in elastic shells: I consider the shape of a deformed elastic shell. Using the fact that the\nlowest-energy, small deformations are along infinitesimal isometries of the\nshell's mid-surface, I describe a class of weakly-stretching deformations for\nthin shells based on the Nambu-Goldstone modes associated with those\nisometries. The main result is an effective theory to describe the diffuse\ndeformations of thin shells that incorporate stretching and bending energies.\nThe theory recovers previous results for the propagation of a \"pinch\" on a\ncylinder. A cone, on the other hand, has two length scales governing the\npersistence of a pinch: one governing the relaxation of the pinch that scales\nwith thickness as a -1/2 power, and one that scales with thickness above which\ndeformations again become isometric. These lengths meet at a critical thickness\nbelow which low energy deformations again become nearly isometric.",
        "positive": "Good Practice Guide on the electrical characterisation of graphene using\n  contact methods: This guide is a deliverable of the Joint Research Project 16NRM01 GRACE --\nDeveloping electrical characterisation methods for future graphene electronics.\nThe project belongs to the European Metrology Programme for Innovation and\nResearch (EMPIR). GRACE is framed within the Normative targeted program, and\nits overall goal is (1) the development of validated protocols for the\nmeasurement of the electrical properties of graphene, and their implementation\nin order to achieve accurate and fastthroughput measurement of graphene; and\n(2) the collaboration with international standardisation committees in order to\ninitiate and develop dedicated documentary standards for the electrical\ncharacterisation of graphene. The adoption of this GPGs and, when published,\nthe corresponding standards, will allow industry to perform accurate\nmeasurements of the electrical properties of graphene and thereby provide\ncustomers with reliable and comparable specifications of graphene as an\nindustrial product."
    },
    {
        "anchor": "Seebeck Coefficient of Two-dimensional Dirac Electrons in Organic\n  Conductor under Pressure: The Seebeck coefficient, which is proportional to a ratio of the\nthermoelectric conductivity to electrical conductivity has been examined for\nDirac electrons in the organic conductor $\\alpha$-(BEDT-TTF)$_2$I$_3$ [BEDT-TTF\ndenotes a molecule given by bis(ethylenedithio)tetrathiafulvalene] under a\nuniaxial pressure using a two-dimensional tight-binding model with both\nimpurity and electron--phonon (e--p) scatterings. We calculate an anomalous\ntemperature ($T$) dependence of the Seebeck coefficient $S_{\\nu}$ with $\\nu =\nx$ (perpendicular to the molecular stacking axis) and $y$, which shows $S_\\nu >\n0$ with a maximum at high temperatures and $S_{\\nu} < 0$ with a minimum at low\ntemperatures.The microscopic mechanism of such a sign change of $S_\\nu$ is\nclarified in terms of the spectral conductivity. The result is compared with\nexperiments on $\\alpha$-(BEDT-TTF)$_2$I$_3$.",
        "positive": "Thermal and Mechanical Properties of some FCC Transition Metals and\n  their Binary Alloys: The temperature dependence of thermodynamic and mechanical properties of six\nfcc transition metals (Ni, Cu, Ag, Au, Pt, Rh) and the alloying behavior of\nAg-Au and Cu-Ni are studied using molecular dynamics (MD). The structures are\ndescribed at elevated temperatures by the force fields developed by Sutton and\nco-workers within the context of tight binding approach. MD algorithms are\nbased on the extended Hamiltonian formalism from the works of Andersen,\nParinello and Rahman, Nose, Hoover and Cagin.The SIMULATOR program that we use\ngenerates information about various physical properties during the run time\nalong with critical trajectory and stepwise information which need to be\nanalyzed post production. The thermodynamic and mechanical properties are\ncalculated in the temperature range between 300K to 1500K with 200K increments\nusing the statistical fluctuation expressions over the MD trajectories."
    },
    {
        "anchor": "Excitonic instability in optically-pumped three-dimensional Dirac\n  materials: Recently it was suggested that transient excitonic instability can be\nrealized in optically-pumped two-dimensional (2D) Dirac materials (DMs), such\nas graphene and topological insulator surface states. Here we discuss the\npossibility of achieving a transient excitonic condensate in optically-pumped\nthree-dimensional (3D) DMs, such as Dirac and Weyl semimetals, described by\nnon-equilibrium chemical potentials for photoexcited electrons and holes.\nSimilar to the equilibrium case with long-range interactions, we find that for\npumped 3D DMs with screened Coulomb potential two possible excitonic phases\nexist, an excitonic insulator phase and the charge density wave phase\noriginating from intranodal and internodal interactions, respectively. In the\npumped case, the critical coupling for excitonic instability vanishes;\ntherefore, the two phases coexist for arbitrarily weak coupling strengths. The\nexcitonic gap in the charge density wave phase is always the largest one. The\ncompetition between screening effects and the increase of the density of states\nwith optical pumping results in a reach phase diagram for the transient\nexcitonic condensate. Based on the static theory of screening, we find that\nunder certain conditions for the value of the dimensionless coupling constant\nscreening in 3D DMs can be weaker than in 2D DMs. Furthermore, we identify the\nsignatures of the transient excitonic condensate that could be probed by\nscanning tunneling spectroscopy, photoemission and optical conductivity\nmeasurements. Finally, we provide estimates of critical temperatures and\nexcitonic gaps for existing and hypothetical 3D DMs.",
        "positive": "Manipulating low-dimensional materials down to the level of single atoms\n  with electron irradiation: Recent advances in scanning transmission electron microscopy (STEM)\ninstrumentation have made it possible to focus electron beams with sub-atomic\nprecision and to identify the chemical structure of materials at the level of\nindividual atoms. Here we discuss the dynamics that are observed in the\nstructure of low-dimensional materials under electron irradiation, and the\npotential use of electron beams for single-atom manipulation. As a\ndemonstration of the latter capability, we show how momentum transfer from the\nelectrons of a 60-keV {\\AA}ngstr\\\"om-sized STEM probe can be used to move\nsilicon atoms embedded in the graphene lattice with atomic precision."
    },
    {
        "anchor": "Exact-exchange energy density in the gauge of a semilocal density\n  functional approximation: Exact-exchange energy density and energy density of a semilocal density\nfunctional approximation are two key ingredients for modeling the static\ncorrelation, a strongly nonlocal functional of the density, through a local\nhybrid functional. Because energy densities are not uniquely defined, the\nconventional (Slater) exact-exchange energy density\n$e_\\mathrm{x}^\\mathrm{ex(conv)}$ is not necessarily well-suited for local\nmixing with a given semilocal approximation. We show how to transform\n$e_\\mathrm{x}^\\mathrm{ex(conv)}$ in order to make it compatible with an\narbitrary semilocal density functional, taking the nonempirical\nmeta-generalized gradient approximation of Tao, Perdew, Staroverov, and\nScuseria (TPSS) as an example. Our additive gauge transformation function\nintegrates to zero, satisfies exact constraints, and is most important where\nthe density is dominated by a single orbital shape. We show that, as expected,\nthe difference between semilocal and exact-exchange energy densities becomes\nmore negative under bond stretching in He$_2^{+}$ and related systems. Our\nconstruction of $e_\\mathrm{x}^\\mathrm{ex(conv)}$ by a\nresolution-of-the-identity method requires uncontracted basis functions.",
        "positive": "First-principles study of the thermoelectric properties of quaternary\n  tetradymite BiSbSeTe2: The electronic and phonon transport properties of quaternary tetradymite\nBiSbSeTe2 are investigated using first-principles approach and Boltzmann\ntransport theory. Unlike the binary counterpart Bi2Te3, we obtain a pair of\nRashba splitting bands induced by the absence of inversion center. Such unique\ncharacteristic could lead to a large Seebeck coefficient even at relatively\nhigher carrier concentration. Besides, we find an ultralow lattice thermal\nconductivity of BiSbSeTe2, especially along the interlayer direction, which can\nbe traced to the extremely small phonon relaxation time mainly induced by the\nmixed covalent bonds. As a consequence, a considerably large ZT value of ~2.0\ncan be obtained at 500 K, indicating that the unique lattice structure of\nBiSbSeTe2 caused by isoelectronic substitution could be an advantage to\nachieving high thermoelectric performance."
    },
    {
        "anchor": "Structural, optical, magnetic and electrical properties of Zn1-x Co (x)\n  O thin films: Despite a considerable effort aiming at elucidating the nature of\nferromagnetism in ZnO-based magnetic semiconductor, its origin still remains\ndebatable. Although the observation of above room temperature ferromagnetism\nhas been reported frequently in the literature by magnetometry measurement, so\nfar there has been no report on correlated ferromagnetism in magnetic, optical\nand electrical measurements. In this paper, we investigate systematically the\nstructural, optical, magnetic and electrical properties of Zn1-x Co (x) O:Al\nthin films prepared by sputtering with x ranging from 0 to 0.33. We show that\ncorrelated ferromagnetism is present only in samples with x > 0.25. In\ncontrast, samples with x < 0.2 exhibit weak ferromagnetism only in magnetometry\nmeasurement which is absent in optical and electrical measurements. We\ndemonstrate, by systematic electrical transport studies that carrier\nlocalization indeed occurs below 20-50 K for samples with x < 0.2; however,\nthis does not lead to the formation of ferromagnetic phase in these samples\nwith an electron concentration in the range of 6 x 10(19) cm(-3) 1 x 10(20)\ncm(-3). Detailed structural and optical transmission spectroscopy analyses\nrevealed that the anomalous Hall effect observed in samples with x > 0.25 is\ndue to the formation of secondary phases and Co clusters.",
        "positive": "Unsupervised learning of atomic environments from simple features: I present a strategy for unsupervised manifold learning on local atomic\nenvironments in molecular simulations based on simple rotation- and\npermutation-invariant three-body features. These features are highly\ndescriptive, generalize to multiple chemical species, and are\nhuman-interpretable. The low-dimensional embeddings of each atomic environment\ncan be used to understand and quantify messy crystal structures such as those\nnear interfaces and defects or well-ordered crystal lattices such as in bulk\nmaterials without modification. The same method can also yield collective\nvariables describing collections of particles such as for an entire simulation\ndomain. I demonstrate the method on colloidal crystallization, ice crystals,\nand binary mesophases to illustrate its broad applicability. In each case, the\nlearned latent space yields insights into the details of the observed\nmicrostructures. For ices and mesophases, supervised classifiers are trained\nbased on the learned manifolds and directly compared against a recent\nneural-network-based approach. Notably, while this method provides comparable\nclassification performance, it can also be deployed on even a handful of\nobserved environments without labels or \\textit{a priori} knowledge. Thus, the\ncurrent approach provides an incredibly versatile strategy to characterize and\nclassify local atomic environments, and may unlock insights in a wide variety\nof molecular simulation contexts."
    },
    {
        "anchor": "Intelligent thermal cloak-concentrators: How to macroscopically control the flow of heat at will is up to now a\nchallenge, which, however, is very important for human life since heat flow is\na ubiquitous phenomenon in nature. Inspired by intelligent electronic\ncomponents or intelligent materials, here we demonstrate, analytically and\nnumerically, a unique class of intelligent bifunctional thermal metamaterials\ncalled thermal cloak-concentrators, which can automatically change from a cloak\n(concentrator) to a concentrator (cloak) when the applied temperature field\ndecreases (increases). For future experimental realization, the behavior is\nalso confirmed by assembling homogeneous isotropic materials according to the\neffective medium theory. The underlying mechanism originates from the effect of\nnonlinearity in thermal conduction. This work not only makes it possible to\nachieve a switchable Seebeck effect, but also offers guidance both for\nmacroscopic manipulation of heat flow at will and for the design of similar\nintelligent multifunctional metamaterials in optics, electromagnetics,\nacoustics, or elastodynamics.",
        "positive": "A simple approach to bulk bioinspired tough ceramics: The development of damage-resistant structural materials that can withstand\nharsh environments is a major issue in materials science and engineering.\nBioinspired brick-and-mortar designs have recently demonstrated a range of\ninteresting mechanical properties in proof-of-concept studies. However,\nreproducibility and scalability issues associated with the actual processing\nroutes have impeded further developments and industrialization of such\nmaterials. Here we demonstrate a simple approach based on uniaxial pressing and\nfield assisted sintering of commercially available raw materials to process\nbioinspired ceramic/ceramic composites of larger thickness than previous\napproaches, with a sample thickness up to 1 cm. The ceramic composite retains\nthe strength typical of dense alumina ($430~\\pm 30MPa$) while keeping the\nexcellent damage resistance demonstrated previously at the millimeter scale\nwith a crack initiation toughness of $6.6MPa.m^{1/2}$ and fracture toughness up\nto $17.6 MPa.m^{1/2}$. These results validate the potential of these\nall-ceramic composites, previously demonstrated at lab scale only, and could\nenable their optimization, scale-up, and industrialization."
    },
    {
        "anchor": "Strain Sensitivity in the Nitrogen 1s NEXAFS Spectra of Gallium Nitride: The Nitrogen 1s near edge X-ray absorption fine structure (NEXAFS) of gallium\nnitride (GaN) shows a strong natural linear dichroism that arises from its\nanisotropic wurtzite structure. An additional spectroscopic variation arises\nfrom lattice strain in epitaxially grown GaN thin films. This variation is\ndirectly proportional to the degree of strain for some spectroscopic features.\nThis strain variation is interpreted with the aid of density functional theory\ncalculations.",
        "positive": "Structural complexity in Prussian blue analogues: We survey the most important kinds of structural complexity in Prussian blue\nanalogues, their implications for materials function, and how they might be\ncontrolled through judicious choice of composition. We focus on six particular\naspects: octahedral tilts, A-site `slides', Jahn--Teller distortions, A-site\nspecies and occupancy, hexacyanometallate vacancies, and framework hydration.\nThe promising K-ion cathode material K$_x$Mn[Fe(CN)$_6$]$_y$ serves as a\nrecurrent example that illustrates many of these different types of complexity.\nOur article concludes with a discussion of how the interplay of various\ndistortion mechanisms might be exploited to optimise the performance of this\nand other related systems, so as to aid in the design of next-generation PBA\nmaterials."
    },
    {
        "anchor": "Ferroelectric driven exciton and trion modulation in monolayer MoSe2 and\n  WSe2: In this work, we show how domain engineered lithium niobate can be used to\nselectively dope monolayer MoSe2 and WSe2 and demonstrate that these\nferroelectric domains can significantly enhance or inhibit photoluminescence\n(PL) with the most dramatic modulation occurring at the heterojunction\ninterface between two domains. A micro-PL and Raman system is used to obtain\nspatially resolved images of the differently doped transition metal\ndichalcogenides (TMDs). The domain inverted lithium niobate causes changes in\nthe TMDs due to electrostatic doping as a result of the remnant polarization\nfrom the substrate. Moreover, the differently doped TMDs (n-type MoSe2 and\np-type WSe2) exhibit opposite PL modulation. Distinct oppositely charged\ndomains were obtained with a 9-fold PL enhancement for the same single MoSe2\nsheet when adhered to the positive (P+) and negative (P-) domains. This sharp\nPL modulation on the ferroelectric domain results from different free electron\nor hole concentrations in the materials conduction band or valence band.\nMoreover, excitons dissociate rapidly at the interface between the P+ and P-\ndomains due to the built-in electric field. We are able to adjust the charge on\nthe P+ and P- domains using temperature via the pyroelectric effect and observe\nrapid PL quenching over a narrow temperature range illustrating the observed PL\nmodulation is electronic in nature. This observation creates an opportunity to\nharness the direct bandgap TMD 2D materials as an active optical component for\nthe lithium niobate platform using domain engineering of the lithium niobate\nsubstrate to create optically active heterostructures that could be used for\nphotodetectors or even electrically driven optical sources on-chip.",
        "positive": "Pressure on charged domain walls and additional imprint mechanism in\n  ferroelectrics: The impact of free charges on the local pressure on a charged ferroelectric\ndomain wall produced by an electric field has been analyzed. A general formula\nfor the local pressure on a charged domain wall is derived considering full or\npartial compensation of bound polarization charges by free charges. It is shown\nthat the compensation can lead to a very strong reduction of the pressure\nimposed on the wall from the electric field. In some cases this pressure can be\ngoverned by small nonlinear effects. It is concluded that the free charge\ncompensation of bound polarization charges can lead to substantial reduction of\nthe domain wall mobility even in the case when the mobility of free charge\ncarriers is high. This mobility reduction gives rise to an additional imprint\nmechanism which may play essential role in switching properties of\nferroelectric materials. The effect of the pressure reduction on the\ncompensated charged domain walls is illustrated for the case of 180-degree\nferroelectric domain walls and of 90-degree ferroelectric domain walls with the\nhead-to-head configuration of the spontaneous polarization vectors."
    },
    {
        "anchor": "Exchange-bias dependent diffusion rate of hydrogen discovered from\n  evolution of hydrogen-induced noncollinear magnetic anisotropy in FePd thin\n  films: Hydrogenation-induced noncollinear magnetic anisotropy is observed from the\nevolution of the magnetic domains in FePd alloy thin films using magneto-optic\nKerr effect (MOKE) microscopy. MOKE images reveal complicated competitions\nbetween different magnetic anisotropies during hydrogen diffusion into the\nfilm. An intriguing enhancement of the hydrogen diffusion rate due to the\npresence of an initial exchange bias induced by a high magnet field is thereby\ndiscovered, pointing to an additional scope of controllability of magnetic\nmetal hydrides as potential future hydrogen sensing and storage materials.",
        "positive": "The origin of hyperferroelectricity in Li$B$O$_3$ ($B$=V, Nb, Ta, Os): The electronic and structural properties of Li$B$O$_3$ ($B$=V, Nb, Ta, Os)\nare investigated via first-principles methods. We show that Li$B$O$_3$ belong\nto the recently proposed hyperferroelectrics, i.e., they all have unstable\nlongitudinal optic phonon modes. Especially, the ferroelectric-like instability\nin the metal LiOsO$_3$, whose optical dielectric constant goes to infinity, is\na limiting case of hyperferroelectrics. Via an effective Hamiltonian, we\nfurther show that, in contrast to normal proper ferroelectricity, in which the\nferroelectric instability usually comes from long-range coulomb interactions,\nthe hyperferroelectric instability is due to the structure instability driven\nby short-range interactions. This could happen in systems with large ion size\nmismatches, which therefore provides a useful guidance in searching for novel\nhyperferroelectrics."
    },
    {
        "anchor": "Phonon-mediated desorption of image-bound electrons from dielectric\n  surfaces: A complete kinetic modeling of an ionized gas in contact with a surface\nrequires the knowledge of the electron desorption time and the electron\nsticking coefficient. We calculate the desorption time for phonon-mediated\ndesorption of an image-bound electron, as it occurs, for instance, on\ndielectric surfaces where desorption channels involving internal electronic\ndegrees of freedom are closed. Because of the large depth of the\npolarization-induced surface potential with respect to the Debye energy\nmulti-phonon processes are important. To obtain the desorption time, we use a\nquantum-kinetic rate equation for the occupancies of the bound surface states,\ntaking two-phonon processes into account in cases where one-phonon processes\nyield a vanishing transition probability, as it is sufficient, for instance,\nfor graphite. Besides producing an estimate for the desorption time of an\nelectron image-bound to a graphite surface, we investigate the desorption\nscenario and show that desorption via cascades over bound states dominates\nunless direct one-phonon transitions from the lowest bound state to the\ncontinuum are possible.",
        "positive": "High-pressure investigations of CaTiO3 up to 60 GPa using X-ray\n  diffraction and Raman spectroscopy: In this work, we investigate calcium titanate (CaTiO3 - CTO) using X-ray\ndiffraction and Raman spectroscopy up to 60 and 55 GPa respectively. Both\nexperiments show that the orthorhombic Pnma structure remains stable up to the\nhighest pressures measured, in contradiction to ab-initio predictions. A fit of\nthe compression data with a second-order Birch-Murnaghan equation of state\nyields a bulk modulus K0 of 181.0(6) GPa. The orthorhombic distortion is found\nto increase slightly with pressure, in agreement with previous experiments at\nlower pressures and the general rules for the evolution of perovskites under\npressure. High-pressure polarized Raman spectra also enable us to clarify the\nRaman mode assignment of CTO and identify the modes corresponding to rigid\nrotation of the octahedra, A-cation shifts and Ti-O bond stretching. The Raman\nsignature is then discussed in terms of compression mechanisms."
    },
    {
        "anchor": "Ferroelectric phase transition in orthorhombic CdTiO3: First-principles\n  studies: The crystal structures and phonon spectra of orthorhombic cadmium titanate\nwith the $Pbnm$ structure and of its two possible ferroelectrically distorted\nphases with $Pbn2_1$ and $Pb2_1m$ space groups were calculated from first\nprinciples within the density functional theory. The obtained structural\nparameters and frequencies of Raman- and infrared-active modes are in good\nagreement with available experimental data for the $Pbnm$ phase. Expansion of\nthe total energy in a Taylor series of two order parameters showed that the\nground state of the system corresponds to the $Pbn2_1$ structure into which the\n$Pbnm$ phase transforms through a second-order phase transition without\nintermediate phases. A substantial discrepancy between the calculated and\nexperimentally observed lattice distortions and spontaneous polarization in the\npolar phase was explained by quantum fluctuations as well as by existence of\ntwinning and competing long-period structures.",
        "positive": "Origins of limited non-basal plasticity in the \u03bc-phase at room\n  temperature: We unveil a new non-basal slip mechanism in the {\\mu}-phase at room\ntemperature using nanomechanical testing, transmission electron microscopy and\natomistic simulation. The (1-105) planar faults with a displacement vector of\n0.07[-5502] can be formed by dislocation glide. They do not disrupt the\nFrank-Kasper packing and therefore enable the accommodation of plastic strain\nat low temperatures without requiring atomic diffusion. The intersections\nbetween the (1-105) planar faults and basal slip result in stress concentration\nand crack nucleation during loading."
    },
    {
        "anchor": "Spin-lattice and electron-phonon coupling in 3$d$/5$d$ hybrid\n  Sr$_3$NiIrO$_6$: While 3$d$-containing materials display strong electron correlations, narrow\nband widths, and robust magnetism, 5$d$ systems are recognized for strong\nspin-orbit coupling, increased hybridization, and more diffuse orbitals.\nCombining these properties leads to novel behavior. Sr$_3$NiIrO$_6$, for\nexample, displays complex magnetism and ultra-high coercive fields - up to an\nincredible 55~T. Here, we combine infrared and optical spectroscopies with\nhigh-field magnetization and first principles calculations to explore the\nfundamental excitations of the lattice and related coupling processes including\nspin-lattice and electron-phonon mechanisms. Magneto-infrared spectroscopy\nreveals spin-lattice coupling of three phonons that modulate the Ir environment\nto reduce the energy required to modify the spin arrangement. While these modes\nprimarily affect exchange within the chains, analysis also uncovers important\ninter-chain motion. This provides a mechanism by which inter-chain interactions\ncan occur in the developing model for ultra-high coercivity. At the same time,\nanalysis of the on-site Ir$^{4+}$ excitations reveals vibronic coupling and\nextremely large crystal field parameters that lead to a t$_{2g}$-derived\nlow-spin state for Ir. These findings highlight the spin-charge-lattice\nentanglement in Sr$_3$NiIrO$_6$ and suggest that similar interactions may take\nplace in other 3$d$/5$d$ hybrids.",
        "positive": "The Deformation Effect on the Electronic Structure of the Graphite\n  Nanoribbon Arrays: We have performed a first-principles study on the deformation effect of the\nelectronic structures of graphite nanoribbon arrays with zigzag edges on both\nsides, and the edge atoms are terminated with hydrogen atoms. A uniaxial strain\nis considered to have deformation effect on the graphite nanoribbons. We found\nthat the antiferromagnetic arrangement of the spin polarizing edges of graphite\nnanoribbon is still more favorable than that with the ferromagnetic arrangement\nunder deformation. We also learned that a tensile strain increases the\nmagnetization of the graphite ribbon while a compressive strain decreases it. A\npositive pressure derivative of the band gap of antiferromagnetic state is\nobserved for the graphite nanoribbon under uniaxial strains. The strain changes\nthe shape of band structure and the band gap; in here, the edge atoms play a\ncrucial role. The deformations are also found to influence the contribution of\nthe edge atoms to the bands near the Fermi level. The deformation effect for\nthe graphite nanoribbon under transverse electric field is also studied."
    },
    {
        "anchor": "Low temperature hcp to monoclinic structural transition in solid\n  C$_{70}$ : Is there an intermediate phase?\": We follow the structural transformation in solid C$_{70}$ from the high\ntemperature hcp to a low temperature monoclinic phase using x-ray diffraction\nstudies at controlled cooling-rates from 0.0033 to 0.42 K/min. Rapid cooling of\nthe sample gives the signature of a two-step transformation which disappears\nwhen the system is transformaed quasi-statically. These experimental results\ncan be rationalised using a simple mean field, Langevin dynamical theory using\na free energy functional with minima corresponding to the parent and two\ncompeting product phases such that one of these product phases remains\nmetastable throughout. The implication of our results on the existence of the\nintermediate phase in the sequence, hcp-dhcp-monoclinic, of structural\ntransitions in solid C$_{70}$ with the lowering of temperature is discussed.",
        "positive": "Size effects in elastic-plastic functionally graded materials: We develop a strain gradient plasticity formulation for composite materials\nwith spatially varying volume fractions to characterize size effects in\nfunctionally graded materials (FGMs). The model is grounded on the\nmechanism-based strain gradient plasticity theory and effective properties are\ndetermined by means of a linear homogenization scheme. Several paradigmatic\nboundary value problems are numerically investigated to gain insight into the\nstrengthening effects associated with plastic strain gradients and\ngeometrically necessary dislocations (GNDs). The analysis of bending in\nmicro-size functionally graded foils shows a notably stiffer response with\ndiminishing thickness. Micro-hardness measurements from indentation reveal a\nsignificant increase with decreasing indenter size. And large dislocation\ndensities in the vicinity of the crack substantially elevate stresses in\ncracked FGM components. We comprehensively assess the influence of the length\nscale parameter and material gradation profile to accurately characterize the\nmicro-scale response and identify regimes of GNDs relevance in FGMs."
    },
    {
        "anchor": "Uniform vapor pressure based CVD growth of MoS2 using MoO3 thin film as\n  a precursor for co-evaporation: Chemical vapor deposition (CVD) is a powerful method employed for high\nquality monolayer crystal growth of 2D transition metal dichalcogenides with\nmuch effort invested toward improving the growth process. Here, we report a\nnovel method for CVD based growth of monolayer molybdenum disulfide (MoS2) by\nusing thermally evaporated thin films of molybdenum trioxide (MoO3) as the\nmolybdenum (Mo) source for co-evaporation. Uniform evaporation rate of the MoO3\nthin films provides uniform Mo vapor which promotes highly reproducible single\ncrystal growth of MoS2 throughout the substrate. These high-quality crystals\nare as large as 95 um and were characterized by scanning electron microscopy,\nRaman spectroscopy, photoluminescence spectroscopy, atomic force microscopy and\ntransmission electron microscopy. The bottom gated field effect transistors\nfabricated using the as grown single crystals show n-type transistor behavior\nwith a good on/off ratio of 10^6 under ambient condition. Our results presented\nhere addresses the precursor vapor control during the CVD process and is a\nmajor step forward toward reproducible growth of MoS2 for future semiconductor\ndevice applications.",
        "positive": "First-principles study of the interaction and charge transfer between\n  graphene and metals: Measuring the transport of electrons through a graphene sheet necessarily\ninvolves contacting it with metal electrodes. We study the adsorption of\ngraphene on metal substrates using first-principles calculations at the level\nof density functional theory. The bonding of graphene to Al, Ag, Cu, Au and\nPt(111) surfaces is so weak that its unique \"ultrarelativistic\" electronic\nstructure is preserved. The interaction does, however, lead to a charge\ntransfer that shifts the Fermi level by up to 0.5 eV with respect to the\nconical points. The crossover from p-type to n-type doping occurs for a metal\nwith a work function ~5.4 eV, a value much larger than the work function of\nfree-standing graphene, 4.5 eV. We develop a simple analytical model that\ndescribes the Fermi level shift in graphene in terms of the metal substrate\nwork function. Graphene interacts with and binds more strongly to Co, Ni, Pd\nand Ti. This chemisorption involves hybridization between graphene $p_z$-states\nand metal d-states that opens a band gap in graphene. The graphene work\nfunction is as a result reduced considerably. In a current-in-plane device\ngeometry this should lead to n-type doping of graphene."
    },
    {
        "anchor": "Electron-phonon-averaged approximation for first-principles computations\n  of electron relaxation times and transport properties in semiconductor\n  materials: We present a simple and efficient approximation to the electron-phonon\nscattering rate suitable for high-throughput screening of candidate materials\nfor thermoelectric devices, based on electronic transport. The method is\napplied to calculate the electronic transport coefficients of half-Heusler\ncompounds, showing agreement with experimental data. By directly computing\nelectrical and the electronic part of the thermal conductivities, we find\ndeviations from the Wiedemann-Franz law in these compounds at high temperatures\nand low carrier concentrations.",
        "positive": "Valley Zeeman effect and Landau levels in Two-Dimensional Transition\n  Metal Dichalcogenides: This paper presents a theoretical description of both the valley Zeeman\neffect (g-factors) and Landau levels in two-dimensional H-phase transition\nmetal dichalcogenides (TMDs) using the Luttinger-Kohn approximation with\nspin-orbit coupling. At the valley extrema in TMDs, energy bands split into\nLandau levels with a Zeeman shift in the presence of a uniform out-of-plane\nexternal magnetic field. The Landau level indices are symmetric in the $K$ and\n$K'$ valleys. We develop a numerical approach to compute the single band\ng-factors from first principles without the need for a sum over unoccupied\nbands. Many-body effects are included perturbatively within the GW\napproximation. Non-local exchange and correlation self-energy effects in the GW\ncalculations increase the magnitude of single band g-factors compared to those\nobtained from density functional theory. Our first principles results give\nspin- and valley-split Landau levels, in agreement with recent optical\nexperiments. The exciton g-factors deduced in this work are also in good\nagreement with experiment for the bright and dark excitons in monolayer\nWSe$_2$, as well as the lowest-energy bright excitons in MoSe$_2$-WSe$_2$\nheterobilayers with different twist angles."
    },
    {
        "anchor": "Water-stable MOFs and Hydrophobically Encapsulated MOFs for CO2 Capture\n  from Ambient Air and Wet Flue Gas: The extra CO2 that has already been released into the atmosphere has to be\nremoved in order to create a world that is carbon neutral. Technologies have\nbeen created to remove carbon dioxide from wet flue gas or even directly from\nambient air, however these technologies are not widely deployed yet. New\ngenerations of creative CO2 capture sorbents have been produced as a\nconsequence of recent improvements in material assembly and surface chemistry.\nWe summarize recent progress on water-stable and encapsulated metal-organic\nframeworks (MOFs) for CO2 capture under a wide range of environmental and\noperating conditions. In particular, newly developed water-stable MOFs and\nhydrophobic coating technologies are discussed with insights into their\nmaterials discovery and the synergistic effects between different components of\nthese hybrid sorbent systems. The future perspectives and directions of\nwater-stable and encapsulated MOFs are also given for Direct Air Capture of CO2\nand CO2 capture from wet flue gas.",
        "positive": "Radiative bistability and thermal memory: We predict the existence of a thermal bistability in many-body systems out of\nthermal equilibrium which exchange heat by thermal radiation using\ninsulator-metal transition (IMT) materials. We propose a writing-reading\nprocedure and demonstrate the possibility to exploit the thermal bistability to\nmake a volatile thermal memory. We show that this thermal memory can be used to\nstore heat and thermal information (via an encoding temperature) for arbitrary\nlong times. The radiative thermal bistability could find broad applications in\nthe domains of thermal management, information processing and energy storage."
    },
    {
        "anchor": "Room temperature chiral magnetic skyrmion in ultrathin magnetic\n  nanostructures: Magnetic skyrmions are chiral spin structures with a whirling configuration.\nTheir topological properties, nanometer size and the fact that they can be\nmoved by small current densities have opened a new paradigm for the\nmanipulation of magnetisation at the nanoscale. To date, chiral skyrmion\nstructures have been experimentally demonstrated only in bulk materials and in\nepitaxial ultrathin films and under external magnetic field or at low\ntemperature. Here, we report on the observation of stable skyrmions in\nsputtered ultrathin Pt/Co/MgO nanostructures, at room temperature and zero\napplied magnetic field. We use high lateral resolution X-ray magnetic circular\ndichroism microscopy to image their chiral N\\'eel internal structure which we\nexplain as due to the large strength of the Dzyaloshinskii-Moriya interaction\nas revealed by spin wave spectroscopy measurements. Our results are\nsubstantiated by micromagnetic simulations and numerical models, which allow\nthe identification of the physical mechanisms governing the size and stability\nof the skyrmions.",
        "positive": "Applying machine learning techniques to predict the properties of\n  energetic materials: We present a proof of concept that machine learning techniques can be used to\npredict the properties of CNOHF energetic molecules from their molecular\nstructures. We focus on a small but diverse dataset consisting of 109 molecular\nstructures spread across ten compound classes. Up until now, candidate\nmolecules for energetic materials have been screened using predictions from\nexpensive quantum simulations and thermochemical codes. We present a\ncomprehensive comparison of machine learning models and several molecular\nfeaturization methods - sum over bonds, custom descriptors, Coulomb matrices,\nbag of bonds, and fingerprints. The best featurization was sum over bonds (bond\ncounting), and the best model was kernel ridge regression. Despite having a\nsmall data set, we obtain acceptable errors and Pearson correlations for the\nprediction of detonation pressure, detonation velocity, explosive energy, heat\nof formation, density, and other properties out of sample. By including another\ndataset with 309 additional molecules in our training we show how the error can\nbe pushed lower, although the convergence with number of molecules is slow. Our\nwork paves the way for future applications of machine learning in this domain,\nincluding automated lead generation and interpreting machine learning models to\nobtain novel chemical insights."
    },
    {
        "anchor": "Self-Learning Kinetic Monte Carlo Simulations of Al Diffusion in Mg: Vacancy-mediated diffusion of an Al atom in pure Mg matrix is studied using\nthe atomistic, on-lattice self-learning kinetic Monte Carlo (SLKMC) method.\nActivation barriers for vacancy-Mg and vacancy-Al atom exchange processes are\ncalculated on-the-fly using the climbing image nudged-elastic band method and\nbinary Mg-Al modified embedded-atom method interatomic potential. Diffusivities\nof an Al atom obtained from SLKMC simulations show the same behavior as\nobserved in experimental and theoretical studies available in the literature,\nthat is, Al atom diffuses faster within the basal plane than along the c-axis.\nAlthough, the effective activation barriers for Al-atom diffusion from SLKMC\nsimulations are close to experimental and theoretical values, the effective\nprefactors are lower than those obtained from experiments. We present all the\npossible vacancy-Mg and vacancy-Al atom exchange processes and their activation\nbarriers identified in SLKMC simulations. A simple mapping scheme to map an HCP\nlattice on to a simple cubic lattice is described, which enables the simulation\nof HCP lattice using on-lattice framework. We also present the pattern\nrecognition scheme which is used in SLKMC simulations to identify the local Al\natom configuration around a vacancy.",
        "positive": "Room Temperature Magnetoelectric Effects on Single Slabs of Z-type\n  Hexaferrites: In this paper, magnetoelectric effects of Sr Z-type hexaferrite,\nSr3Fe24Co2O41, at room temperature is measured. The change in remanence\nmagnetization was measured by applying a DC voltage or electric field across a\nslab of hexaferrite. Changes of ~ 18% in remanence was observed in an electric\nfield of 10,000V/cm implying a similar change in the microwave permeability at\nfrequencies below 3GHz. In these types of measurements high resistivity is\ncritical in order to reduce current flow in the hexaferrite. The resistivity of\nthe hexaferrite was raised to 4.28x10^8 ohm?-cm by annealing under oxygen\npressure. The measurements indicate that indeed electric polarization and\nmagnetization changes were induced by the application of magnetic and electric\nfields, respectively. The implications for microwave applications appear to be\nvery promising at room temperature."
    },
    {
        "anchor": "Novel doping alternatives for single-layer transition metal\n  dichalcogenides: Successful doping of single-layer transition metal dichalcogenides (TMDs)\nremains a formidable barrier to their incorporation into a range of\ntechnologies. We use density functional theory to study doping of molybdenum\nand tungsten dichalcogenides with a large fraction of the periodic table. An\nautomated analysis of the energetics, atomic and electronic structure of\nthousands of calculations results in insightful trends across the periodic\ntable and points out promising dopants to be pursued experimentally. Beyond\npreviously studied cases, our predictions suggest promising substitutional\ndopants that result in p-type transport and reveal interesting physics behind\nthe substitution of the metal site. Doping with early transition metals (TMs)\nleads to tensile strain and a significant reduction in the bandgap. The bandgap\nincreases and strain is reduced as the d-states are filled into the mid TMs;\nthese trends reverse are we move into the late TMs. Additionally, the Fermi\nenergy increases monotonously as the d-shell is filled from the early to mid\nTMs and we observe few to no gap states indicating the possibility of both p-\n(early TMs) and n- (mid TMs) type doping. Quite surprisingly, the simulations\nindicate the possibility of interstitial doping of TMDs; the energetics reveal\nthat a significant number of dopants, increasing in number from molybdenum\ndisulfide to diselenide and to ditelluride, favor the interstitial sites over\nadsorbed ones. Furthermore, calculations of the activation energy associated\nwith capturing the dopants into the interstitial site indicate that the process\nis kinetically possible. This suggets that interstitial impurities in TMDs are\nmore common than thought to date and we propose a series of potential\ninterstitial dopants for TMDs relevant for application in nanoelectronics based\non a detailed analysis of the predicted electronic structures.",
        "positive": "Detection of melting by in-situ observation of spherical-drop formation\n  in laser-heated diamond-anvil cells: A simple method for detection of melting event in laser-heated diamond anvil\ncells (DACs) is introduced. The melting is registered optically by the\nformation of spherical drops of the investigated material as heated in an inert\npressure transmitting medium. Feasibility of the method is demonstrated on the\nexamples of metal (iron and gold) and iron oxide (Fe2O3), materials molten at\npressures over 40 GPa employing a portable laser heating system."
    },
    {
        "anchor": "Effect of Stacking Fault Energy on Mechanism of Plastic Deformation in\n  Nanotwinned FCC Metals: Starting from a semi-empirical potential designed for Cu, we developed a\nseries of potentials that provide essentially constant values of all\nsignificant (calculated) materials properties except for the intrinsic stacking\nfault energy, which varies over a range that encompasses the lowest and highest\nvalues observed in nature. These potentials were employed in molecular dynamics\n(MD) simulations to investigate how stacking fault energy affects the\nmechanical behavior of nanotwinned face-centered cubic (fcc) materials. The\nresults indicate that properties such as yield strength and microstructural\nstability do not vary systematically with stacking fault energy, but rather\nfall into two distinct regimes corresponding to low and high stacking fault\nenergies.",
        "positive": "A stochastic model of solid state thin film deposition: application to\n  chalcopyrite growth: Developing high fidelity quantitative models of solid state reaction systems\ncan be challenging, especially in deposition systems where, in addition to the\nmultiple competing processes occurring simultaneously, the solid interacts with\nits atmosphere. In this work, we develop a model for the growth of a thin solid\nfilm where species from the atmosphere adsorb, diffuse, and react with the\nfilm. The model is mesoscale and describes an entire film with thickness on the\norder of microns. Because it is stochastic, the model allows us to examine\ninhomogeneities and agglomerations that would be impossible to characterize\nwith deterministic methods. We demonstrate the modeling approach with the\nexample of chalcopyrite Cu(InGa)(SeS)$_2$ thin film growth via precursor\nreaction, which is a common industrial method for fabricating thin film\nphotovoltaic modules. The model is used to understand how and why through-film\nvariation in the composition of Cu(InGa)(SeS)$_2$ thin films arises and\npersists. We believe that the model will be valuable as an effective\nquantitative description of many other materials systems used in\nsemiconductors, energy storage, and other fast-growing industries."
    },
    {
        "anchor": "Electronic and optical properties of LiBC: LiBC, a semiconducting ternary borocarbide constituted of the lightest\nelements only, has been synthesized and characterized by x-ray powder\ndiffraction, dielectric spectroscopy, and conductivity measurements. Utilizing\nan infrared microscope the phonon spectrum has been investigated in single\ncrystals. The in-plane B-C stretching mode has been detected at 150 meV,\nnoticeably higher than in AlB2, a non-superconducting isostructural analog of\nMgB2. It is this stretching mode, which reveals a strong electron-phonon\ncoupling in MgB2, driving it into a superconducting state below 40 K, and is\nbelieved to mediate predicted high-temperature superconductivity in hole-doped\nLiBC [H. Rosner, A. Kitaigorodsky, and W. E. Pickett, Phys. Rev. Lett. 88,\n127001 (2002)].",
        "positive": "Comment on \"Chiral Phase Transition in Charge Ordered 1T-TiSe2\" and\n  Supplementary Material on \"First-order Forbidden X-ray Diffraction\": A prior report of the emergence of chirality for the (2x2x2) charge density\nwave (CDW) in TiSe2 has attracted much interest; the drastic symmetry breaking\nis highly unusual with few precedents [1]. In that study, key evidence was\nprovided by x-ray diffraction measurements of two superlattice reflections,\n(1.5 1.5 0.5) and (2.5 1 0). The (2.5 1 0) reflection appeared to show an\nanomalously large intensity and a transition onset at ~7 K below that of the\n(1.5 1.5 0.5) reflection. These observations, aided by modeling, were cited as\nevidence for a separate chiral transition. In this Comment, we show that the\nprior conclusions based on x-ray diffraction are erroneous. There is just one\ntransition, and it is achiral."
    },
    {
        "anchor": "Interaction of $\\langle a \\rangle$ prismatic screw dislocations with the\n  $\u03b1-\u03b2$ interface side face in $\u03b1-\u03b2$ Ti alloys: Slip transmission across $\\alpha-\\beta$ interfaces is of great significance\nin understanding the strength of $\\alpha-\\beta$ Ti alloys for aerospace\napplications. Molecular statics (MS) and molecular dynamics (MD) simulations\nwere conducted to investigate the mechanisms of slip transmission of $\\langle a\n\\rangle$ prismatic screw dislocations across the $\\alpha-\\beta$ interface side\nface. In these simulations, the $\\alpha$ phase consisted of pure HCP Ti whereas\nthe $\\beta$ phase was modeled as Ti$_{60}$Nb$_{40}$ BCC random alloy using a\nTi-Nb interatomic potential. Firstly, the misfit dislocations structure on the\n$\\alpha-\\beta$ interface side face has been characterized from MS simulations.\nThis predicted dislocation structure is in good agreement with experimental\nobservations in Ti-alloys. Secondly, MD simulations of the interaction of\n$[a_1]$, $[a_2]$, and $[a_3]$ prismatic screw dislocations with the interface\nside face in an $\\alpha-\\beta$ bi-crystal were performed at different\ntemperatures. A distinct barrier of the interface side face to different types\nof dislocation transmission was found. The origin of this anisotropy in the\nslip transmission is due to the relative misalignment of the slip systems\nbetween the $\\alpha$ and the $\\beta$ phases from the Burgers orientation\nrelationship. Finally, the mechanisms of slip transmission of each dislocation\ntype were analyzed in a detailed atomistic description and compared to\nexperimental observations.",
        "positive": "Chemically induced ferromagnetism near room temperature in single\n  crystal (Zn$_{1-x}$Cr$_{x}$)Te half-metal: Magnetic semiconductors are at the core of recent spintronics research\nendeavors. Chemically doped II-VI diluted magnetic semiconductors, such as\n(Zn$_{1-x}$Cr$_{x}$)Te, provide promising platform in this quest. However, a\ndetailed knowledge of the microscopic nature of magnetic ground state is\nnecessary for any practical application. Here, we report on the synergistic\nstudy of (Zn$_{1-x}$Cr$_{x}$)Te single crystals using elastic neutron\nscattering measurements and density functional calculations. For the first\ntime, our research unveils the intrinsic properties of ferromagnetic state in\nmacroscopic specimen of (Zn$_{0.8}$Cr$_{0.2}$)Te. The ferromagnetism is onset\nat $T_c \\sim$ 290 K and remains somewhat independent to modest change in the\nsubstitution coefficient x. We show that magnetic moments on Zn/Cr site develop\nferromagnetic correlation in a-c plane with large ordered moment of $\\mu$ =\n3.08 $\\mu_B$. Magnetic moment across the lattice is induced via the mediation\nof Te site, uncoupled to the number of dopant carriers as inferred from the\ndensity functional calculation. Additionally, the ab-initio calculations also\nreveal half-metallicity in x = 0.2 composition. These properties are highly\ndesirable for future spintronic applications."
    },
    {
        "anchor": "Structural and dynamic disorder, not ionic trapping, controls charge\n  transport in highly doped conducting polymers: Doped organic semiconductors are critical to emerging device applications,\nincluding thermoelectrics, bioelectronics, and neuromorphic computing devices.\nIt is commonly assumed that low conductivities in these materials result\nprimarily from charge trapping by the Coulomb potentials of the dopant\ncounter-ions. Here, we present a combined experimental and theoretical study\nrebutting this belief. Using a newly developed doping technique, we find the\nconductivity of several classes of high-mobility conjugated polymers to be\nstrongly correlated with paracrystalline disorder but poorly correlated with\nionic size, suggesting that Coulomb traps do not limit transport. A general\nmodel for interacting electrons in highly doped polymers is proposed and\ncarefully parameterized against atomistic calculations, enabling the\ncalculation of electrical conductivity within the framework of transient\nlocalisation theory. Theoretical calculations are in excellent agreement with\nexperimental data, providing insights into the disordered-limited nature of\ncharge transport and suggesting new strategies to further improve\nconductivities.",
        "positive": "G band Raman double resonance in twisted bilayer graphene: an evidence\n  of band splitting and folding: The stacking faults (deviates from Bernal) will break the translational\nsymmetry of multilayer graphenes and modify their electronic and optical\nbehaviors to the extent depending on the interlayer coupling strength. This\npaper addresses the stacking-induced band splitting and folding effect on the\nelectronic band structure of twisted bilayer graphene. Based on the\nfirst-principles density functional theory study, we predict that the band\nfolding effect of graphene layers may enable the G band Raman double resonance\nin the visible excitation range. Such prediction is confirmed experimentally\nwith our Raman observation that the resonant energies of the resonant G mode\nare strongly dependent on the stacking geometry of graphene layers."
    },
    {
        "anchor": "Environmentally-Sensitive Theory of Electronic and Optical Transitions\n  in Atomically-Thin Semiconductors: We present an electrostatic theory of band gap renormalization in\natomically-thin semiconductors that captures the strong sensitivity to the\nsurrounding dielectric environment. In particular, our theory aims to correct\nknown band gaps, such as that of the three-dimensional bulk crystal. Combining\nour quasiparticle band gaps with an effective mass theory of excitons yields\nenvironmentally-sensitive optical gaps as would be observed in absorption or\nphotoluminescence. For an isolated monolayer of MoS$_2$, the presented theory\nis in good agreement with ab initio results based on the GW approximation and\nthe Bethe-Salpeter equation. We find that changes in the electronic band gap\nare almost exactly offset by changes in the exciton binding energy, such that\nthe energy of the first optical transition is nearly independent of the\nelectrostatic environment, rationalizing experimental observations.",
        "positive": "Prediction of topological phases in metastable ferromagnetic MPX$_3$\n  monolayers: Density functional theory calculations are carried out to study the\nelectronic and topological properties of $M$P$X_3$ ($M$ = Mn, Fe, Co, Ni, and\n$X$ = S, Se) monolayers in the ferromagnetic (FM) metastable magnetic state. We\nfind that FM MnPSe$_3$ monolayers host topological semimetal signatures that\nare gapped out when spin-orbit coupling (SOC) is included. These findings are\nsupported by explicit calculations of the Berry curvature and the Chern number.\nThe choice of the Hubbard-$U$ parameter to describe the $d$-electrons is\nthoroughly discussed, as well as the influence of using a hybrid-functional\napproach. The presence of band inversions and the associated topological\nfeatures are found to be formalism-dependent. Nevertheless, routes to achieve\nthe topological phase via the application of external biaxial strain are\ndemonstrated. Within the hybrid-functional picture, topological band structures\nare recovered under a pressure of 15% (17 GPa). The present work provides a\npotential avenue for uncovering new topological phases in metastable\nferromagnetic phases."
    },
    {
        "anchor": "Faster Exact Exchange in Periodic Systems using Single-precision\n  Arithmetic: Density-functional theory simplifies many-electron calculations by\napproximating the exchange and correlation interactions with a one-electron\noperator that is a functional of the density. Hybrid functionals incorporate\nsome amount of exact exchange, improving agreement with measured electronic and\nstructural properties. However, calculations with hybrid functionals require\nsubstantial computational resources, limiting their use. By calculating the\nexchange interaction of periodic systems with single-precision arithmetic, the\ncomputation time is cut nearly in half with a negligible loss in accuracy. This\nimprovement makes exact exchange calculations quicker and more feasible,\nespecially for high-throughput calculations. Example hybrid density-functional\ntheory calculations of band energies, forces, and x-ray absorption spectra show\nthat this single-precision implementation maintains accuracy with significantly\nreduced runtime and memory requirements.",
        "positive": "Unconventional magnetic ferroelectricity in the quadruple perovskite\n  NaMn$_7$O$_{12}$: By means of magnetic, specific heat and pyroelectric measurements, we report\non magnetic ferroelectricity in the quadruple perovskite \\namno, characterized\nby a canted antiferromagnetic (AFM) CE structure. Surprisingly,\nferroelectricity is concomitant to a dramatic broadening of the magnetic\nhysteresis loop, well below the AFM ordering temperature. This unconventional\nbehavior shows that the formation of ferroelectric domains is induced by the\nsymmetric exchange interaction in the local scale, e.g. at magnetic domain\nboundaries or defects. The value of electric polarization, $P = 0.027 \\mu$C\ncm$^{-2}$, measured in polycrystalline samples is comparatively large as\ncompared to other magnetic multiferroics, suggesting that the above scenario is\npromising indeed for the rational design of practical multiferroic materials."
    },
    {
        "anchor": "Defect driven flexo-chemical coupling in thin ferroelectric films: Using Landau-Ginzburg-Devonshire theory, we considered the impact of the\nflexoelectro-chemical coupling on the size effects inpolar properties and phase\ntransitions of thin ferroelectric films with a layer of elastic defects. We\ninvestigated a typical case, when defects fill a thin layer below the top film\nsurface with a constant concentration creating an additional gradient of\nelastic fields. The defective surface of the film is not covered with an\nelectrode, but instead with an ultra-thin layer of ambient screening charges,\ncharacterized by a surface screening length. This geometry is typical for the\nscanning probe piezoelectric force microscopy. Obtained results revealed an\nunexpectedly strong effect of the joint action of Vegard stresses and\nflexoelectric effect (shortly flexo-chemical coupling) on the ferroelectric\ntransition temperature, distribution of the spontaneous polarization and\nelastic fields, domain wall structure and period in thin PbTiO3 films\ncontaining a layer of elastic defects. A nontrivial result is the\nferroelectricity persisting at film thicknesses below 4 nm, temperatures lower\nthan 350 K and relatively high surface screening length (~0.1 nm). The origin\nof this phenomenon is the re-building of the domain structure in the film\n(namely the cross-over from c-domain stripes to a-type closure domains) when\nits thickness decreases below 4 nm, conditioned by the flexoelectric coupling\nand facilitated by negative Vegard effect. For positive Vegard effect, thicker\nfilms exhibit the appearance of pronounced maxima on the thickness dependence\nof the transition temperature, whose position and height can be controlled by\nthe defect type and concentration. The revealed features may have important\nimplications for miniaturization of ferroelectric-based devices.",
        "positive": "On the Brittle-to-Ductile Transition of the As-cast TiVNbTa Refractory\n  High-entropy Alloy: The fracture properties of as-cast TiVNbTa, a refractory high-entropy alloy\n(RHEA), were investigated using four-point bending tests from -139C to 20C\nunder a strain-rate of 10-3 s-1. From those tests and fractography, the\nconditional fracture toughness values and the brittle-to-ductile transition\ntemperature were obtained. The brittle-to-ductile transition temperature was\nbetween -47C to -27C, which gives an estimated activation energy value of\n0.52+-0.09 eV for the alloy. This study provides a preliminary understanding of\nthe nature of dislocation motion in a relatively ductile RHEA."
    },
    {
        "anchor": "Magnetic interactions and magnetocaloric effect in\n  (La0.5Pr0.5)0.6Ba0.4MnO3: Effect of A-site co-doping: We report on the structural, magnetic, and magnetocaloric properties of\npolycrystalline (La0.5Pr0.5)0.6Ba0.4MnO3 (LPBMO), which was fabricated by a\nconventional solid-state reaction method. LPBMO undergoes a second-order\nparamagnetic to ferromagnetic (PM-FM) phase transition around a Curie\ntemperature TC ~ 277 K. The maximum magnetic entropy change is ~ 3.22 J kg-1\nK-1 for a magnetic field change of 5 T. Based on the modified-Arrott plot and\nthe iterative Kouvel Fisher methods, a set of critical exponents (beta = 0.514,\ngamma = 1.164, and delta = 3.265) are determined. These values are close to\nthose expected for the mean field model with long range interactions below TC\nand for the 3D-Ising model with short range interactions above TC. Effect of\nA-site co-doping (La,Pr) on the magnetic and magnetocaloric properties of LPBMO\nis analyzed and discussed.",
        "positive": "Ultrafast hot-electron induced quenching of Tb4f magnetic order: We have investigated ultrafast quenching of the Tb4f magnetic order in\nCo74Tb26 alloys, induced by femtosecond hot-electrons pulses. The hot-electron\npulses were produced in specific non-magnetic capping layers by infrared fs\nlaser pulses. Our experimental results show that sub-picosecond dynamics of\nTb4f magnetic moments can be induced by non-thermal and thermal hot-electrons.\nWe further demonstrate that the demagnetization efficiencies of non-thermal and\nthermal hot electrons are similar. However, the characteristic demagnetization\ntimes show values of 0.35 ps for non-thermal hot-electrons excitations and 1.2\nps for thermal hot-electrons excitations. We explain this temporal elongation\nby the propagation time of thermal hot-electrons through the 15 nm thick CoTb\nfilm."
    },
    {
        "anchor": "Electric field induced topological phase transition and large\n  enhancements of spin-orbit coupling and Curie temperature in two-dimensional\n  ferromagnetic semiconductors: Tuning topological and magnetic properties of materials by applying an\nelectric field is widely used in spintronics. In this work, we find a\ntopological phase transition from topologically trivial to nontrivial states at\nan external electric field of about 0.1 V/A in MnBi$_2$Te$_4$ monolayer that is\na topologically trivial ferromagnetic semiconductor. It is shown that when\nelectric field increases from 0 to 0.15 V/A, the magnetic anisotropy energy\n(MAE) increases from about 0.1 to 6.3 meV, and the Curie temperature Tc\nincreases from 13 to about 61 K. The increased MAE mainly comes from the\nenhanced spin-orbit coupling due to the applied electric field. The enhanced Tc\ncan be understood from the enhanced $p$-$d$ hybridization and decreased energy\ndifference between $p$ orbitals of Te atoms and $d$ orbitals of Mn atoms.\nMoreover, we propose two novel Janus materials MnBi$_2$Se$_2$Te$_2$ and\nMnBi$_2$S$_2$Te$_2$ monolayers with different internal electric polarizations,\nwhich can realize quantum anomalous Hall effect (QAHE) with Chern numbers $C$=1\nand $C$=2, respectively. Our study not only exposes the electric field induced\nexotic properties of MnBi2Te4 monolayer, but also proposes novel materials to\nrealize QAHE in ferromagnetic Janus semiconductors with electric polarization.",
        "positive": "Parallel-leaky capacitance equivalent circuit model for MgO magnetic\n  tunnel junctions: The capacitance of MgO based magnetic tunnel junctions (MTJs) has been\nobserved to be magnetic field dependent. We propose an equivalent circuit for\nthe MTJs with a parallel-leaky capacitance (Cl) across the series combination\nof geometric and interfacial capacitance. The analysis of junctions with\ndifferent tunneling magnetoresistance values suggests higher Cl for low TMR\njunctions. Using Cole-Cole plots the capacitive nature of MTJs is manifested.\nFitting with Maxwell-Wagner capacitance model validates the RC parallel network\nmodel for MTJs and the extracted field dependent parameters match with the\nexperimental values."
    },
    {
        "anchor": "Dislocation breakaway from nanoparticle array linear complexions:\n  Plasticity mechanisms and strength scaling laws: Linear complexions are stable defect states, where the stress field\nassociated with a dislocation induces a local phase transformation that remains\nrestricted to nanoscale dimensions. As these complexions are born at the\ndefects which control plasticity in metals, it is crucial to understand their\nimpact on subsequent mechanical properties. In this work, atomistic modeling is\nused to understand how dislocation mechanics are altered by the presence of\nnanoparticle array linear complexions in a Ni-Al alloy. Molecular dynamics\nsimulations are used to identify the critical shear stress needed to drive\ndislocation breakaway, first for nanoparticle arrays formed by Monte\nCarlo/molecular dynamics methods to represent realistic configurations and\nsubsequently for simplified models that allow the effects of particle spacing\nand size to be varied in a controlled manner. A combined bowing and progressive\nunpinning mechanism is uncovered, leading to the demonstration of a new\nstrength scaling law that differs in keys ways from classical Orowan bowing.",
        "positive": "$\\mathrm{TlP_5}$: An unexplored direct band gap 2D semiconductor with\n  ultra-high carrier mobility: Two-dimensional materials with a proper band gap and high carrier mobility\nare urgently desired in the field of nanoelectronics. We propose a novel\ntwo-dimensional crystal monolayer $\\mathrm{TlP_5}$, which is dynamically and\nthermodynamically stable and possesses a direct band gap of 2.02 eV with high\ncarrier mobilities (13960 $\\mathrm{cm^2\\ V^{-1}s^{-1}}$ for electrons and 7560\n$\\mathrm{cm^2\\ V^{-1}s^{-1}}$ for holes), comparable to that of phosphorene.\nThe band gap value and band characteristics of monolayer $\\mathrm{TlP_5}$ can\nbe adjusted by biaxial and uniaxial strains, and excellent optical absorption\nover the visible-light range is predicted. These properties, especially for the\nbalanced high mobilities for not only the electrons but also the holes, render\nmonolayer $\\mathrm{TlP_5}$ an exciting functional material for future\nnanoelectronics and optoelectronic applications."
    },
    {
        "anchor": "Thermal magnetization fluctuations in thin films and a new physical form\n  for magnetization damping: The effect of thermal fluctuations on a thin film magnetoresistive element\nhas been calculated. The technique involves adding to the basic spin dynamics a\ngeneral form of interaction with a thermal bath. For a general anisotropic\nmagnetic system the resulting equation can be written as a Langevin equation\nfor a harmonic oscillator. Our approach predicts two times smaller noise power\nat low frequencies than the conventional stochastic Landau-Lifshitz-Gilbert\nequation. It is shown that equivalent results can be obtained by introducing a\ntensor phenomenological damping term to the gyromagnetic dynamics driven by a\nthermal fluctuating field.",
        "positive": "Pulse-assisted magnetization switching in magnetic nanowires at\n  picosecond and nanosecond timescales with low energy: Detailed understanding of spin dynamics in magnetic nanomaterials is\nnecessary for developing ultrafast, low-energy and high-density spintronic\nlogic and memory. Here, we develop micromagnetic models and analytical\nsolutions to elucidate the effect of increasing damping and uniaxial anisotropy\non magnetic field pulse-assisted switching time, energy and field requirements\nof nanowires with perpendicular magnetic anisotropy and yttrium iron\ngarnet-like spin transport properties. A nanowire is initially magnetized using\nan external magnetic field pulse (write) and self-relaxation. Next, magnetic\nmoments exhibit deterministic switching upon receiving 2.5 ns-long external\nmagnetic pulses in both vertical polarities. Favorable damping\n({\\alpha}~0.1-0.5) and anisotropy energies (10^4-10^5 J m^-3) allow for as low\nas picosecond magnetization switching times. Magnetization reversal with fields\nbelow coercivity was observed using spin precession instabilities. A\ncompetition or a nanomagnetic trilemma arises among the switching rate, energy\ncost and external field required. Developing magnetic nanowires with optimized\ndamping and effective anisotropy could reduce the switching energy barrier down\nto 3163kBT at room temperature. Thus, pulse-assisted picosecond and low energy\nswitching in nanomagnets could enable ultrafast nanomagnetic logic and cellular\nautomata."
    },
    {
        "anchor": "All-optical reversible manipulation of exciton and trion emissions in\n  monolayer WS2: Monolayer transition metal dichalcogenides (TMDs) are direct gap\nsemiconductors emerging promising applications in diverse optoelectronic\ndevices. To improve performance, recent investigations have been systematically\nfocused on the tuning of their optical properties. However, an all-optical\napproach with the reversible feature is still a challenge. Here we demonstrate\nthe tunability of the photoluminescence (PL) properties of monolayer WS2 via\nlaser irradiation. The modulation of PL intensity, as well as the conversion\nbetween neutral exciton and charged trion have been readily and reversibly\nachieved by using different laser power densities. We attribute the reversible\nmanipulation to the laser-assisted adsorption and desorption of gas molecules,\nwhich will deplete or release free electrons from the surface of WS2 and thus\nmodify its PL properties. This all-optical manipulation, with advantages of\nreversibility, quantitative control, and high spatial resolution, suggests\npromising applications of TMDs monolayers in optoelectronic and nanophotonic\napplications, such as optical data storage, micropatterning, and display.",
        "positive": "Controlling the balance between remote, pinhole, and van der Waals\n  epitaxy of Heusler films on graphene/sapphire: Remote epitaxy on monolayer graphene is promising for synthesis of highly\nlattice mismatched materials, exfoliation of free-standing membranes, and\nre-use of expensive substrates. However, clear experimental evidence of a\nremote mechanism remains elusive. In many cases, due to contaminants at the\ntransferred graphene/substrate interface, alternative mechanisms such as\npinhole-seeded lateral epitaxy or van der Waals epitaxy can explain the\nresulting exfoliatable single-crystalline films. Here, we find that growth of\nthe Heusler compound GdPtSb on clean graphene on sapphire substrates produces a\n30 degree rotated epitaxial superstructure that cannot be explained by pinhole\nor van der Waals epitaxy. With decreasing growth temperature the volume\nfraction of this 30 degree domain increases compared to the direct epitaxial 0\ndegree domain, which we attribute to slower surface diffusion at low\ntemperature that favors remote epitaxy, compared to faster surface diffusion at\nhigh temperature that favors pinhole epitaxy. We further show that careful\ngraphene/substrate annealing ($T\\sim 700 ^\\circ C$) and consideration of the\nfilm/substrate vs film/graphene lattice mismatch are required to obtain epitaxy\nto the underlying substrate for a variety of other Heusler films, including\nLaPtSb and GdAuGe. The 30 degree rotated superstructure provides a possible\nexperimental fingerprint of remote epitaxy since it is inconsistent with the\nleading alternative mechanisms."
    },
    {
        "anchor": "Studying Pulsed Laser Deposition conditions for Ni/C-based multi-layers: Nickel carbon based multi-layers are a viable route towards future hard X-ray\nand soft $\\gamma$-ray focusing telescopes. Here, we study the Pulsed Laser\nDeposition growth conditions of such bilayers by Reflective High Energy\nElectron Diffraction, X-ray Reflectivity and Diffraction, Atomic Force\nMicroscopy, X-ray Photoelectron Spectroscopy and cross-sectional Transmission\nElectron Microscopy analysis, with emphasis on optimization of process pressure\nand substrate temperature during growth. The thin multi-layers are grown on a\ntreated SiO substrate resulting in Ni and C layers with surface roughnesses\n(RMS) of $\\leq$0.2 nm. Small droplets resulting during melting of the targets\nsurface increase the roughness, however, and can not be avoided. The sequential\nprocess at temperatures beyond 300$^\\circ$C results into intermixing between\nthe two layers, being destructive for the reflectivity of the multi-layer.",
        "positive": "Experimental observation of highly anisotropic elastic properties of\n  two-dimensional black arsenic: Anisotropic two-dimensional layered materials with low-symmetric lattices\nhave attracted increasing attention due to their unique orientation-dependent\nmechanical properties. Black arsenic (b-As), with the puckered structure,\nexhibits extreme in-plane anisotropy in optical, electrical and thermal\nproperties. However, experimental research on mechanical properties of b-As is\nvery rare, although theoretical calculations predicted the exotic elastic\nproperties of b-As, such as anisotropic Young's modulus and negative Poisson's\nratio. Herein, experimental observations on highly anisotropic elastic\nproperties of b-As were demonstrated using our developed in situ tensile\nstraining setup based on the effective microelectromechanical system. The\ncyclic and repeatable load-displacement curves proved that Young's modulus\nalong zigzag direction was ~1.6 times greater than that along armchair\ndirection, while the anisotropic ratio of ultimate strain reached ~2.5,\nattributed to hinge structure in armchair direction. This study could provide\nsignificant insights to design novel anisotropic materials and explore their\npotential applications in nanomechanics and nanodevices."
    },
    {
        "anchor": "Valley-Contrasting Orbital Magnetic Moment Induced Negative\n  Magnetoresistance: The valley-contrasting orbital magnetic moment of Bloch electrons allows the\nlifting of valley degeneracy by an out-of-plane magnetic field. We demonstrate\nthat this leads to negative magnetoresistance, utilizing a gapped\ntwo-dimensional multi-valley model as an example. An intuitive physical picture\nin terms of the increased carrier density from a magnetic gating effect is\nproposed for this negative magnetoresistance. In particular, giant negative\nmagnetoresistance is achieved after one of the two valleys is depleted by the\nmagnetic field. This new mechanism of negative magnetoresistance is argued to\nbe relevant in ionic-liquid gated gapped graphene with small effective mass.",
        "positive": "Reconstruction-Stabilized Epitaxy of LaCoO3/SrTiO3(111) Heterostructures\n  by Pulsed Laser Deposition: Unlike widely explored complex oxide heterostructures grown along [001], the\nstudy of [111]-oriented heterointerfaces are very limited thus far. One of the\nmain challenges is to overcome the polar discontinuity that hinders the epitaxy\nof atomically sharp interfaces. Here, by taking the LaCoO3/SrTiO3(111) as a\nprototype, we show that the reconstruction, which effectively compensates the\nsurface polarity, can stabilize the epitaxy of the heterostructure with polar\ndiscontinuity. Reconstructed substrate surface is prepared, while the growth is\ncontrolled to form reconstruction on the film surface. To suppress the chemical\ndiffusion across the interface, the growth is interrupted between each unit\ncell layer to allow the lattice relaxation at a lowered temperature. In this\nway, high quality two-dimensional growth is realized and the heterointerfaces\nexhibit sharpness at the atomic scale. Our work provides a path to precisely\ncontrol the growth of complex oxide heterostructures along polar orientations\nthat exhibit emergent quantum phenomena."
    },
    {
        "anchor": "Influence of microstructure and atomic-scale chemistry on iron ore\n  reduction with hydrogen at 700\u00b0C: With 1.85 billion tons produced per year, steel is the most important\nmaterial class in terms of volume and environmental impact. While steel is a\nsustainability enabler, for instance through lightweight design, magnetic\ndevices, and efficient turbines, its primary production is not. For 3000 years,\niron has been reduced from ores using carbon. Today 2.1 tons CO2 are produced\nper ton of steel, causing 30% of the global CO2 emissions in the manufacturing\nsector, which translates to 6.5% of the global CO2 emissions. These numbers\nqualify iron- and steel-making as the largest single industrial greenhouse gas\nemission source. The envisaged future industrial route to mitigate these CO2\nemissions targets green hydrogen as a reductant. Although this reaction has\nbeen studied for decades, its kinetics is not well understood, particularly\nduring the wustite reduction step which is dramatically slower than the\nhematite reduction. Many rate-limiting factors of this reaction are set by the\nmicro- and nanostructure as well as the local chemistry of the ores. Their\nquantification allows knowledge-driven ore preparation and process optimization\nto make the hydrogen-based reduction of iron ores commercially viable, enabling\nthe required massive CO2 mitigation to ease global warming. Here, we report on\na multi-scale structure and composition analysis of iron reduced from hematite\nwith pure H2, reaching down to near-atomic scale.",
        "positive": "Equivariant analytical mapping of first principles Hamiltonians to\n  accurate and transferable materials models: We propose a scheme to construct predictive models for Hamiltonian matrices\nin atomic orbital representation from ab initio data as a function of atomic\nand bond environments. The scheme goes beyond conventional tight binding\ndescriptions as it represents the ab initio model to full order, rather than in\ntwo-centre or three-centre approximations. We achieve this by introducing an\nextension to the Atomic Cluster Expansion (ACE) descriptor that represents\nHamiltonian matrix blocks that transform equivariantly with respect to the full\nrotation group. The approach produces analytical linear models for the\nHamiltonian and overlap matrices. Through an application to aluminium, we\ndemonstrate that it is possible to train models from a handful of structures\ncomputed with density functional theory, and apply them to produce accurate\npredictions for the electronic structure. The model generalises well and is\nable to predict defects accurately from only bulk training data."
    },
    {
        "anchor": "A thermodynamically consistent theory of stress-gradient plasticity: As an extension to strain-gradient models of size-dependent plastic\nbehaviour, this work proposes a model for a stress-gradient theory. The model\nis distinguished from earlier works on the topic by its being embedded in a\nthermodynamically consistent framework. The development is carried out in the\ncontext of single-crystal plasticity, and draws on thermodynamically consistent\nmodels for single-crystal conventional and strain-gradient plasticity. The\nmodel is explored numerically using the example of torsion of a thin wire\ncomprising a face centred cubic crystal, and its behaviour compared with that\nbased on a recent disequilibrium density model of size-dependent plasticity.",
        "positive": "Discovery of Electrochemically Induced Grain Boundary Transitions: Electric fields and currents, which are used in innovative materials\nprocessing and electrochemical energy conversion, can often alter\nmicrostructures in unexpected ways. However, little is known about the\nunderlying mechanisms. Using ZnO-Bi2O3 as a model system, this study uncovers\nhow an applied electric current can change the microstructural evolution\nthrough an electrochemically induced grain boundary (GB) transition. By\ncombining aberration-corrected electron microscopy, photoluminescence\nspectroscopy, first-principles calculations, a generalizable thermodynamic\nmodel, and ab initio molecular dynamics, this study reveals that\nelectrochemical reduction can cause a GB disorder-to-order transition to\nmarkedly increase GB diffusivities and mobilities. Consequently, abruptly\nenhanced or abnormal grain growth takes place. These findings advance our\nfundamental knowledge of GB complexion (phase-like) transitions and electric\nfield effects on microstructural stability and evolution, with broad scientific\nand technological impacts. A new method to tailor the GB structures and\nproperties, as well as the microstructures, electrochemically can also be\nenvisioned."
    },
    {
        "anchor": "Electron Holographic Mapping of Structural and Electronic Reconstruction\n  at Mono- and Bilayer Steps of h-BN: Here, by making use of medium and high resolution autocorrected off-axis\nelectron holography, we directly probe the electrostatic potential as well as\nin-plane and out-of-plane charge delocalization at edges and steps in\nmultilayer hexagonal boron nitride. In combination with ab-initio calculations,\nthe data allows to directly reveal the formation of out-of-plane covalent bonds\nat folded zig-zag edges and steps comprising two monolayers and the absence of\nwhich at monolayer steps. The technique paves the way for studying other charge\n(de)localization phenomena in 2D materials, e.g., at polar edges, topological\nedge states and defects.",
        "positive": "Stress focusing and damage protection in topological Maxwell\n  metamaterials: Advances in the field of topological mechanics have highlighted a number of\nspecial mechanical properties of Maxwell lattices, including the ability to\nfocus zero-energy floppy modes and states of self-stress (SSS) at their edges\nand interfaces. Due to their topological character, these phenomena are\nprotected against perturbations in the lattice geometry and material\nproperties, which makes them robust against the emergence of structural\nnon-idealities, defects, and damage. Recent computational work has shown that\nthe ability of Maxwell lattices to focus stress along prescribed SSS domain\nwalls can be harnessed for the purpose of protecting other regions in the bulk\nof the lattice from detrimental stress concentration and, potentially,\ninhibiting the onset of fracture mechanisms at stress hot spots such as holes\nand cracks. This property provides a powerful, geometry-based tool for the\ndesign of lattice configurations that are robust against damage and fracture.\nIn this work, we provide a comprehensive experiment-driven exploration of this\nidea in the context of realistic structural lattices characterized by\nnon-ideal, finite-thickness hinges. Our experiments document the onset of\npronounced domain wall stress focusing, indicating a remarkable robustness of\nthe polarization even in the presence of the dilutive effects of the structural\nhinges. We also demonstrate that the polarization protects the lattice against\npotential failure from defected hinges and cracks in the bulk. Finally, we\nillustrate numerically the superiority of SSS domain walls compared to other\ntrivial forms of reinforcements."
    },
    {
        "anchor": "Cross-polarized optical absorption of single-walled nanotubes probed by\n  polarized photoluminescence excitation spectroscopy: Cross-polarized absorption peaks of isolated single-walled carbon nanotubes\nwere observed by a polarized photoluminescence excitation (PLE) spectroscopy.\nUsing a simple theory for PL anisotropy, the observed PLE spectra are\ndecomposed into 'pure' components of the photoexcitation for incident light\npolarized parallel and perpendicular to the SWNT axis. For several (n, m)\nSWNTs, distinct peaks corresponding to perpendicular excitation were observed.\nThe measured transition energies for perpendicular excitations were\nblue-shifted compared to the qualitative values predicted within a\nsingle-particle theory. The results indicate a smaller exciton binding energy\nfor perpendicular excitations than for parallel excitations.",
        "positive": "Designing inorganic semiconductors with cold-rolling processability: While metals can be readily processed and reshaped by cold rolling, most bulk\ninorganic semiconductors are brittle materials that tend to fracture when\nplastically deformed. Manufacturing thin sheets and foils of inorganic\nsemiconductors is therefore a bottleneck problem, severely restricting their\nuse in flexible electronics applications. It was recently reported that a few\nsingle-crystalline two-dimensional van der Waals (vdW) semiconductors, such as\nInSe, are deformable under compressive stress. Here we demonstrate that\nintralayer fracture toughness can be tailored via compositional design to make\ninorganic semiconductors processable by cold rolling. We report systematic ab\ninitio calculations covering a range of van der Waals semiconductors homologous\nto InSe, leading to material-property maps that forecast trends in both the\nsusceptibility to interlayer slip and the intralayer fracture toughness against\ncracking. GaSe has been predicted, and experimentally confirmed, to be\npractically amenable to being rolled to large (three quarters) thickness\nreduction and length extension by a factor of three. Our findings open a new\nrealm of possibility for alloy selection and design towards processing-friendly\ngroup-III chalcogenides for flexible electronic and thermoelectric\napplications."
    },
    {
        "anchor": "Influence of electronic structure parameters on the electrical transport\n  and magnetic properties of $Y_{2-x}Bi_xIr_2O_7$ pyrochlore iridates: We report the systematic study of structural, magnetic and electrical\ntransport properties of $Y_{2-x}Bi_xIr_2O_7$ (x = 0.0, 0.1, 0.2, 0.3)\npyrochlore iridates. The chemical doping enhances electrical conductivity and\nantiferromagnetic correlation substantially. The replacement of non-magnetic\n$Y^{3+}$ ion with non-magnetic $Bi^{3+}$ in $Y_2Ir_2O_7$ tends to reduce the\noctahedral distortion thus enhancing the antiferromagnetic correlation. Raman\nspectroscopy shows that the $Ir-O$ bond contract slightly and the $R-O'$ bond\nturn longer as disorder and phononic oscillation are reduced with $Bi$ doping,\nleading to wider $t_{2g}$ bands, which enhances the electrical conductivity.\nAdditionally, the enhancement in electrical conductivity and antiferromagnetic\ncorrelation with $Bi^{3+}$ doping is attributed to the hybridization between\nthe $Y^{3+}(4p)$/$Bi^{3+}(6s/6p)$ orbital with $Ir^{4+}(5d)$ orbital as a\nresult of enhancement in $Ir-O-Ir$ bond angle and contraction in $Ir-O$ bond\nlength.",
        "positive": "Frenkel-Kontorova Model of Vacancy-Line Interactions on Ga/Si(112):\n  Formalism: We describe in greater detail the exactly solvable microscopic model we have\ndeveloped for analyzing the strain-mediated interaction of vacancy lines in a\npseudomorphic adsorbate system (Phys. Rev. Lett., to appear). The model is\napplied to Ga/Si(112) by extracting values for the microscopic parameters from\ntotal-energy calculations. The results, which are in good agreement with\nexperimental observations, reveal an unexpectedly complex interplay between\ncompressive and tensile strain within the mixed Ga-Si surface layer."
    },
    {
        "anchor": "Microscopic approach to the evaluation of diffusion coefficients for\n  substitutional f.c.c. solid solutions: The microscopic theory of atomic diffusion kinetics is used for f.c.c.\nsubstitutional solid solutions. Within this approach, the short-range order\nrelaxation is due to the atomic migration. Experimental data on the time\ndependence of radiation diffuse scattering are used for the determination of\nmicroscopic characteristics of atomic migration. The model takes into account\nthe discrete and anisotropic character of atomic jumps in a long-range field of\nthe concentration heterogeneities of interacting atoms. Such a consideration is\napplied for a close-packed Ni-Fe solid solution. Atomic-jumps' probabilities\nare estimated that allows to determine the diffusion coefficients and\nactivation energies. Independent kinetic experimental data about a time\nevolution of long-range order are also used to calculate diffusivities in\nL12-Ni-Fe alloy.",
        "positive": "Theory of defects in one-dimensional systems: the case of Al in Si\n  nanowires: The energetic cost of creating a defect within a host material is given by\nthe formation energy. Here we present a formulation allowing the calculation of\nformation energies in one-dimensional nanostructures, which overcomes the\ndifficulties involved in defining the chemical potential of the constituent\nspecies and the possible passivation of the surface. We also develop a formula\nfor the Madelung correction for general dielectric tensors and computational\ncell shapes. We apply this formalism to the formation energies of charged Al\nimpurities in silicon nanowires, obtaining concentrations significantly larger\nthan in their bulk counterparts."
    },
    {
        "anchor": "In-Situ Studies of Stress Environment in Amorphous Solids Using\n  Negatively Charged Nitrogen Vacancy Centers in Nanodiamond: Amorphous solids, which show characteristic differences from crystals, are\ncommon in daily usage. Glasses, gels, and polymers are familiar examples, and\npolymers are particularly important in terms of their role in construction and\ncrafting. Previous studies have mainly focused on the bulk properties of\npolymeric products, and the local properties are less discussed. Here, we\ndesigned a distinctive protocol using the negatively charged nitrogen vacancy\ncenter in nanodiamond to study properties inside polymeric products in situ.\nChoosing the curing of poly dimethylsiloxane and the polymerization of\ncyanoacrylate as subjects of investigation, we measured the time dependence of\nlocal pressure and strain in the materials during the chemical processes. From\nthe measurements, we were able to probe the local shear stress inside the two\npolymeric substances in situ. By regarding the surprisingly large shear stress\nas the internal tension, we attempted to provide a microscopic explanation for\nthe ultimate tensile strength of a bulk solid. Our current methodology is\napplicable to any kind of transparent amorphous solids with the stress in the\norder of MPa and to the study of in situ properties in nanoscale. With better\napparatus, we expect the limit can be pushed to sub-MPa scale.",
        "positive": "Electronic and magnetic properties of twisted graphene nanoribbon and\n  M\u00f6bius strips: first-principles calculations: The geometrical, electronic, and magnetic properties of twisted zigzag-edged\ngraphene nanoribbons (ZGNRs) and novel graphene M\\\"obius strips (GMS) are\nsystematically investigated using first-principles density functional\ncalculations. The structures of ZGNRs and GMS are optimized, and their\nstabilities are examined. The molecular energy levels and the spin polarized\ndensity of states are calculated. It is found that for twisted ZGNRs, the\natomic bonding energy decreases quadratically with the increase of the twisted\nangle, and the HOMO-LUMO gap are varying in a sine-like behavior with the\ntwisted angle. The calculated spin densities reveal that the ZGNRs and GMS have\nantiferromagnetic ground states, which persist during the twisting. The spin\nflips on the zigzag edges of GMS are observed at some positions."
    },
    {
        "anchor": "Structure Analysis using Time-of-Flight Momentum Microscopy with Hard\n  X-rays: Status and Prospects: X-ray photoelectron diffraction (XPD) has developed into a powerful technique\nfor the structural analysis of solids. Extension of the technique into the\nhard-X-ray range (hXPD) gives access to true bulk information. Here we give a\nstatus report on hXPD experiments using a novel full-field imaging technique:\nTime-of-flight momentum microscopy (ToF-MM). A special variant of ToF-MM is\ncapable of recording high kinetic energies (up to >7keV) and enlarged\nk-fields-of-view. We present applications that are specific for high kinetic\nenergies. The strong site specificity of hXPD is exemplified for NbSe2, the\ncubic-to-tetragonal transition in SrTiO3 and the zinc-blende structure in\nepitaxial GaAs films. Bloch-wave calculations show a very good agreement with\nexperiment and reveal fingerprint-like signatures of emitter sites in host\nlattices. We show a dopant-site analysis in two semiconductors (Mn in GaAs and\nTe in Si). Hard-X-ray ARPES plus core-level hXPD enable eliminating the strong\ndiffraction signature imprinted in HARPES maps.",
        "positive": "A Geometric Field Theory of Dislocation Mechanics: In this paper a geometric field theory of dislocation dynamics and finite\nplasticity in single crystals is formulated. Starting from the multiplicative\ndecomposition of the deformation gradient into elastic and plastic parts, we\nuse Cartan's moving frames to describe the distorted lattice structure via\ndifferential $1$-forms. In this theory the primary fields are the dislocation\nfields, defined as a collection of differential $2$-forms. The defect content\nof the lattice structure is then determined by the superposition of the\ndislocation fields. All these differential forms constitute the internal\nvariables of the system. The evolution equations for the internal variables are\nderived starting from the kinematics of the dislocation 2-forms, which is\nexpressed using the notions of flow and of Lie derivative. This is then coupled\nwith the rate of change of the lattice structure through Orowan's equation. The\ngoverning equations are derived using a two-potential approach to a variational\nprinciple of the Lagrange-d'Alembert type. As in the nonlinear setting the\nlattice structure evolves in time, the dynamics of dislocations on slip systems\nis formulated by enforcing some constraints in the variational principle. Using\nthe Lagrange multipliers associated with these constraints, one obtains the\nforces that the lattice exerts on the dislocation fields in order to keep them\ngliding on some given crystallographic planes. Moreover, the geometric\nformulation allows one to investigate the integrability -- and hence the\nexistence -- of glide surfaces, and how the glide motion is affected by it.\nLastly, a linear theory for small dislocation densities is derived, allowing\none to identify the nonlinear effects that do not appear in the linearized\nsetting."
    },
    {
        "anchor": "Influence of deformation and annealing twinning on the microstructure\n  and texture evolution of face-centered cubic high-entropy alloys: The influence of the physical mechanisms activated during deformation and\nannealing on the microstructure and texture evolution as well as on the\nmechanical properties in the equiatomic CoCrFeMnNi high-entropy alloy (HEA)\nwere investigated. A combination of cold rolling and annealing was used to\ninvestigate the HEA in the deformed, recovered, partially recrystallized, and\nfully recrystallized states. Detailed microstructure and texture analysis was\nperformed by electron backscatter diffraction, transmission electron\nmicroscopy, and X-ray diffraction. The mechanical properties were evaluated\nusing uniaxial tensile testing. A specific focus of this investigation was put\non studying the influence of deformation and annealing twinning on the material\nbehavior. It was substantiated that during cold rolling deformation, twinning\nfacilitates the transition from the Cu-type to the Brass-type texture, whereas\nannealing-twinning leads to a strong modification of the texture formed during\nrecrystallization. The formation of specific twin orientations and the\nrandomization of the recrystallization texture were proven by experiments as\nwell as by cellular automaton simulations. During tension of the cold-rolled\nand annealed material high work-hardenability was observed. We attribute this\nbehavior primarily to the dominance of planar dislocation slip and reduced\ntendency for dynamic recovery, since deformation twinning was observed to\nactivate only in the non-recrystallized grains and thus, contributed minimally\nto the overall plasticity. The correlation between deformation/annealing\ntwinning and the material behavior was discussed in detail.",
        "positive": "Structure-property relationships for weak-ferromagnetic perovskites: Despite several decades of active experimental and theoretical studies of\nrare-earth orthoferrites, the mechanism of the formation of specific magnetic,\nmagnetoelastic, optical, and magneto-optical properties remains a subject of\ndiscussion. This paper provides an overview of simple theoretical model\napproaches to quantitatively describing the structure-property relationships,\nin particular, interplay between FeO$_6$ octahedral deformations/rotations and\nmain magnetic and optic characteristics such as N\\'{e}el temperature, overt and\nhidden canting of magnetic sublattices, magnetic and magnetoelastic anisotropy,\noptic and photoelastic anisotropy."
    },
    {
        "anchor": "Orientational tuning of the Fermi sea of confined electrons at the\n  SrTiO3 (110) and (111) surfaces: We report the existence of confined electronic states at the (110) and (111)\nsurfaces of SrTiO3. Using angle-resolved photoemission spectroscopy, we find\nthat the corresponding Fermi surfaces, subband masses, and orbital ordering are\ndifferent from the ones at the (001) surface of SrTiO3. This occurs because the\ncrystallographic symmetries of the surface and sub-surface planes, and the\nelectron effective masses along the confinement direction, influence the\nsymmetry of the electronic structure and the orbital ordering of the t2g\nmanifold. Remarkably, our analysis of the data also reveals that the carrier\nconcentration and thickness are similar for all three surface orientations,\ndespite their different polarities. The orientational tuning of the microscopic\nproperties of two-dimensional electron states at the surface of SrTiO3 echoes\nthe tailoring of macroscopic (e.g. transport) properties reported recently in\nLaAlO3/SrTiO3 (110) and (111) interfaces, and is promising for searching new\ntypes of 2D electronic states in correlated-electron oxides.",
        "positive": "Relative abundances and enantiomerization energy of the chiral Cu$_{13}$\n  cluster at finite temperature: This study reports the lowest energy structure of bare Cu$_{13}$ nanoclusters\nas a pair of enantiomers for temperatures ranging from 20 to 1200 K. Moreover,\nwe compute the enantiomerization energy for the interconversion from\n$\\mathcal{M}$ to $\\mathcal{P}$ structures in the chiral putative global minimum\nfor temperatures ranging from 20 to 1300 K. Additionally, employing statistical\nthermodynamics and nanothermodynamics, we compute the Boltzmann Probability for\neach particular isomer as a function of temperature. To achieve that, we\nexplore the free energy surface of the Cu$_{13}$ cluster, employing a genetic\nalgorithm coupled with density functional theory and statistical\nthermodynamics. Moreover, we discuss the energetic ordering of structures\ncomputed at the DFT level and compared to high level DLPNO-CCSD(T1) reference\nenergies, and we present chemical bonding analysis using the AdNDP method in\nthe chiral putative global minimum. Based on the computed relative abundances,\nour results show that the chiral putative global minimum strongly dominates for\ntemperatures ranging from 20 to 1100 K."
    },
    {
        "anchor": "Electronic structure of magnetic molecules V15: LDA+U calculations,\n  X-ray emission and photoelectron spectra: Electronic structure of V$_{15}$ magnetic molecules (K$_6$ [V$_{15}$ As$_6$\nO$_{42}$ (H$_2$O)] \\cdot 8H$_2$O)$ has been studied using LSDA+U band structure\ncalculations, and measurements of X-ray photoelectron (valence band, core\nlevels) and X-ray fluorescence spectra (vanadium K$\\beta_5$ and L$_{2,3}$, and\noxygen K$\\alpha$). Experiments confirm that vanadium ions are tetravalent in\nV$_{15}$, and their local atomic structure is close to that of CaV$_3$O$_7$.\nComparison of experimental data with the results of electronic structure\ncalculations show that the LSDA+U method provides a description of the\nelectronic structure of V$_{15}$ which agrees well with experiments.",
        "positive": "Textures in Polygonal Arrangements of Square Nanoparticles in Nematic\n  Liquid Crystals Matrices: A systematic analysis of defect textures in facetted nanoparticles with\npolygonal configurations embedded in a nematic matrix is performed using the\nLandau-de Gennes model, homeotropic strong anchoring in a square domain with\nuniform alignment in the outer boundaries. Defect and textures are analyzed as\nfunctions of temperature T, polygon size R, and polygon number N. For nematic\nnanocomposites, the texture satisfies a defect charge balance equation between\nbulk and surface (particle corner) charges. Upon decreasing the temperature,\nthe central bulk defects split and together with other -1/2 bulk defects, are\nabsorbed by the nanoparticle's corners. Increasing the lattice size decreases\nconfinement and eliminates bulk defects. Increasing the polygon number\nincreases the central defect charge at high temperature and the number of\nsurface defects at lower temperatures. The excess energy per particle is lower\nin even than in odd polygons, and it is minimized for a square particle\narrangement. These discrete modeling results show for first time that even\nunder strong anchoring, defects are attached to particles as corner defects,\nleaving behind a low energy homogeneous orientation field that favors\nnanoparticle ordering in nematic matrices. These new insights are consistent\nwith recent thermodynamic approaches to nematic nanocomposites that predict the\nexistence of novel nematic/crystal phases and can be used to design\nnanocomposites with orientational and positional order."
    },
    {
        "anchor": "Universality of the Scaling Law for Ferroic Domains: We show how the periodicity of 180^{o} domains as a function of crystal\nthickness scales with the thickness of the domain walls both for ferroelectric\nand for ferromagnetic materials. We derive an analytical expression for the\nuniversal scaling factor and use this to calculate domain wall thickness and\ngradient coefficients (exchange constants) in some ferroic materials. We then\nuse these to discuss some of the wider implications for the physics of\nferroelectric nano-devices and periodically poled photonic crystals.",
        "positive": "Magnetic dielectric- graphene- ferroelectric system as a promising\n  non-volatile device for modern spintronics: The conductivity of the system magnetic dielectric (EuO) - graphene channel -\nferroelectric substrate was considered. The magnetic dielectric locally\ntransforms the band spectrum of graphene by inducing an energy gap in it and\nmaking it spin-asymmetric with respect to the free electrons. The range of\nspontaneous polarization (2- 5)mC/m2 that can be easily realized in thin films\nof proper and incipient ferroelectrics, was under examination. It was\ndemonstrated, that if the Fermi level in the graphene channel belongs to energy\nintervals where the graphene band spectrum, modified by EuO, becomes sharply\nspin-asymmetric, such a device can be an ideal non-volatile spin filter.\nControlling of the Fermi level (e.g. by temperature that changes ferroelectric\npolarization) can convert a spin filter to a spin valve."
    },
    {
        "anchor": "Microscale stress-geometry interactions in an additively manufactured\n  NiTi cardiovascular stent: A synchrotron dual imaging tomography and\n  diffraction study: This study explores cardiovascular stents fabricated using laser powder bed\nfusion (LPBF); an emerging method to offer patient-specific customisable parts.\nHere, the shape memory alloy NiTi, in a near equiatomic composition, was\ninvestigated to deconvolve the material response from macroscopic component\neffects. Specifically, stress-geometry interactions were revealed, in-situ, for\na minaturised cardiovascular stent subjected to an externally applied\ncylindrical stress whilst acquiring synchrotron X-ray imaging and diffraction\ndata. The approach enabled the collection of spatially resolved micromechanical\ndeformation data; the formation of stress-induced martensite and R-phase was\nevident, occurring in locations near junctions between stent ligaments where\nstress concentrations exist. In the as-fabricated condition, hardness maps were\nobtained through nanoindentation, demonstrating that the localised deformation\nand deformation patterning is further controlled by porosity and\nmicrostructural heterogeneity. Electron backscatter diffraction (EBSD)\nsupported these observations, showing a finer grain structure near stent\njunctions with higher associated lattice curvature. These features, combined\nwith stress concentrations when loaded will initiate localised phase\ntransformations. If the stent was subjected to repeated loading, representing\nin-vivo conditions, these regions would be susceptible to cyclic damage through\ntransformation memory loss, leading to premature component failure. This study\nhighlights the challenges that must be addressed for the post-processing\ntreatment of LABF-processed stents for healthcare-related applications.",
        "positive": "Theory of temperature dependent phonon-renormalized properties: We present a general harmonic theory for the temperature dependence of\nphonon-renormalized properties of solids. Firstly, we formulate a perturbation\ntheory in phonon-phonon interactions to calculate the phonon renormalization of\nphysical quantities. Secondly, we propose two new schemes for extrapolating\nphonon zero-point corrections from temperature dependent data that improve the\naccuracy by an order of magnitude compared to previous approaches. Finally, we\nconsider the low-temperature limit of the class of observables that includes\nthe electronic band gap, obtaining a $T^4$ dependence in three dimensions,\n$T^2$ in two dimensions, and $T^{3/2}$ in one dimension."
    },
    {
        "anchor": "Local Diamagnetic Susceptibility of Quasi-Two-Dimensional Graphite: A sample of quasi-two-dimensional graphite (QTDG) whose magnetic properties\nare described within the Dirac fermion model is investigated by the nuclear\nmagnetic resonance (NMR) and scanning tunneling microscopy (STM) techniques.\nThe broad spectrum of the sample points to a large dispersion of crystallite\nsizes in this system, which is also confirmed by STM data. It is established\nthat the local diamagnetic susceptibility may substantially exceed the average\nvalue over the sample and reaches an abnormally high value of $-1.3\\times\n10^{-4}$ emu/g at $T = 4.2$ K, which is greater than the corresponding value of\nhighly oriented graphite by a factor of four.",
        "positive": "Effects of Graphene/BN Encapsulation, Surface Functionalization and\n  Molecular Adsorption on the Electronic Properties of Layered InSe: A\n  First-Principles Study: By using first-principles calculations, we investigated the effects of\ngraphene/boron nitride (BN) encapsulation, surface functionalization by\nmetallic elements (K, Al, Mg and typical transition metals) and molecules\n(tetracyanoquinodimethane (TCNQ) and tetracyanoethylene (TCNE)) on the\nelectronic properties of layered indium selenide (InSe). It was found that an\nopposite trend of charge transfer is possible for graphene (donor) and BN\n(acceptor), which is dramatically different from phosphorene where both\ngraphene and BN play the same role (donor). For InSe/BN heterostructure, a\nchange of the interlayer distance due to an out-of-plane compression can\neffectively modulate the band gap. Strong acceptor abilities to InSe were found\nfor the TCNE and TCNQ molecules. For K, Al and Mg-doped monolayer InSe, the\ncharge transfer from K and Al atoms to the InSe surface was observed, causing\nan n-type conduction of InSe, while p-type conduction of InSe observed in case\nof the Mg-doping. The atomically thin structure of InSe enables the possible\nobservation and utilization of the dopant-induced vertical electric field\nacross the interface. A proper adoption of the n- or p-type dopants allows for\nthe modulation of the work function, the Fermi level pinning, the band bending,\nand the photo-adsorbing efficiency near the InSe surface/interface.\nInvestigation on the adsorption of transition metal atoms on InSe showed that\nTi-, V-, Cr-, Mn-, Co-adsorbed InSe are spin-polarized, while Ni-, Cu-, Pd-,\nAg- and Au-adsorbed InSe are non-spin-polarized. Our results shed lights on the\npossible ways to protect InSe structure and modulate its electronic properties\nfor nanoelectronics and electrochemical device applications."
    },
    {
        "anchor": "Diffusion of Mn in gallium nitride: Experiment and modelling: The control over the structural homogeneity is of paramount importance for\nternary nitride compounds - the second most important semiconducting\nmaterial-class after Si, due to its unrivalled applicability in\noptoelectronics, and high power/high frequency electronics. Therefore it is\ntimely to investigate possible mechanisms influencing the crystallographic\nconstitution of the material. In this work the diffusion mechanism of manganese\nin gallium nitride is investigated in two types of epilayers: Mn implanted\nmetalorganic vapour phase epitaxy grown GaN and (Ga,Mn)N solid solution grown\nby molecular beam epitaxy. The extent of the Mn diffusion is established by\nsecondary ion mass spectrometry. Analysis of the Mn profiles in the implanted\nsamples in the frame of the infinite source diffusion led to the establishment\nfor the first time of the pre-exponential factor DO = 2x10-4 cm2/s and\ndiffusion activation energy EA = 1.8 eV describing the diffusion coefficient of\nMn in GaN. Modelling of the out-diffusion of Mn from (Ga,Mn)N layers based on\nthese values in turn allows to provide an explanation of the origin of the\nubiquitously observed near-the-surface sizable depletion of Mn in (Ga,Mn)N,\nresulting from the blocking of the Mn out-diffusion by Mn-oxide and the\ncorrespondingly formed space-charge layer on the surface.",
        "positive": "Magnetic interactions in IV-VI diluted magnetic semiconductors: Diluted magnetic semiconductors (DMS) are interesting because of the\ninterplay between the electronic and magnetic subsystems. We describe selected\nmagnetic properties of IV-VI diluted magnetic semiconductors, looking at the\nsimilarities and differences between magnetic properties of II-VI, IV-VI, and\nIII-V DMS. We focus on the influence of the crystalline and electronic\nstructure of the material on its magnetic properties, especially on the\nexchange interactions among magnetic ions. We describe methods of determination\nof the exchange parameters by using different experimental techniques, such as\nmeasurements of magnetic susceptibility, magnetization, and specific heat. We\nfollow the development in the material technology from bulk crystals to thin\nfilms and nanostructures."
    },
    {
        "anchor": "Measurements of Broadband Negative Index in Space-Coiling Acoustic\n  Metamaterials: We report the experimental demonstration of broadband negative refractive\nindex obtained in a labyrinthine acoustic metamaterial structure. Two different\napproaches were employed to prove the metamaterial negative index nature:\none-dimensional extractions of effective parameters from reflection and\ntransmission measurements, and two-dimensional prism-based measurements that\nconvincingly show the transmission angle corresponding to negative refraction.\nThe transmission angles observed in the latter case also agree very well with\nthe refractive index obtained in the one-dimensional measurements and numerical\nsimulations. We expect this labyrinthine metamaterial to become the unit cell\nof choice for practical acoustic metamaterial devices that require broadband\nand significantly negative indexes of refraction.",
        "positive": "Electronic Coupling between the Unoccupied States of the Organic and\n  Inorganic Sub-Lattices of Methylammonium Lead Iodide a Hybrid\n  Organic-Inorganic Perovskite Single Crystal: Organic-inorganic halide perovskites have been intensively re-investigated\ndue to their applications, yet the opto-electronic function of the organic\ncation remains unclear. Through organic-selective resonant Auger electron\nspectroscopy measurements on well-defined single crystal surfaces, we find\nevidence for electronic coupling in the unoccupied states between the organic\nand inorganic sub-lattices of the prototypical hybrid perovskite, which is\ncontrary to the notion based on previous studies that the organic cation is\nelectronically inert. The coupling is relevant for electron dynamics in the\nmaterial and for understanding opto-electronic functionality."
    },
    {
        "anchor": "Electronic structure and optical properties of Na$_2$KSb and NaK$_2$Sb\n  from first-principles many-body theory: In the search for novel materials for vacuum electron sources, multi-alkali\nantimonides and in particular sodium-potassium-antimonides have been recently\nregarded as especially promising due to their favorable electronic and optical\nproperties. In the framework of density-functional theory and many-body\nperturbation theory, we investigate the electronic structure and the dielectric\nresponse of two representative members of this family, namely Na$_2$KSb and\nNaK$_2$Sb. We find that both materials have a direct gap, which is on the order\nof 1.5 eV in Na$_2$KSb and 1.0 eV in NaK$_2$Sb. In either system, valence and\nconduction bands are dominated by Sb states with p- and s-character,\nrespectively. The imaginary part of the dielectric function, computed upon\nexplicit inclusion of electron-hole interactions to characterize the optical\nresponse of the materials, exhibits maxima starting from the near-infrared\nregion, extending up to the visible and the ultraviolet band. With our\nanalysis, we clarify that the lowest-energy excitations are non-excitonic in\nnature and that their binding energy is on the order of 100 meV. Our results\nconfirm the potential of Na$_2$KSb and NaK$_2$Sb as photoemissive materials for\nvacuum electron sources, photomultipliers, and imaging devices.",
        "positive": "Insight into the Induction Hardening Behavior of a New 0.40% C\n  Microalloyed Steel: Effects of Initial Microstructure and Thermal Cycles: The induction hardening behavior of a new, hot-rolled 0.4 wt.% carbon steel\nwith the two different starting microstructures of upper and lower bainite has\nbeen simulated using a Gleeble 3800. The effect of heating rate in the range 1\n- 500 {\\deg}C/s on austenite grain size distribution has been rationalized.\nDilatometry together with Scanning Electron Microscopy combined with Electron\nBackscatter Diffraction analyses and thermodynamic simulations provide insight\ninto the austenite formation mechanisms that operate at different heating\nrates. Two main mechanisms of austenite formation during re-austenitization\nwere identified: diffusional and diffusionless (massive). At conventional (1-5\n{\\deg}C/s) and fast (10-50 {\\deg}C/s) heating rates the austenite formation\nmechanism and kinetics are controlled by diffusion, whereas at ultrafast\nheating rates (100-500 {\\deg}C/s) the formation of austenite starts by\ndiffusion control, but is later overtaken by a massive transformation\nmechanism. Comprehensive thermodynamic descriptions of the influence of\ncementite on austenite formation are discussed. The finest austenite grain size\nand the highest final hardness are achieved with a lower bainite starting\nmicrostructure processed with a heating rate of 50 {\\deg}C/s to an\naustenitization temperature of 850 {\\deg}C followed by cooling at 60 {\\deg}C/s.\nKeywords Induction Hardening, Heating Rate, Cementite Dissolution, Prior\nAustenite Grain Size, Dilatometry"
    },
    {
        "anchor": "Anomalous Hall effect and magnetoresistance in micro-ribbons of the\n  magnetic Weyl semimetal candidate PrRhC2: PrRhC2 belongs to the rare-earth carbides family whose properties are of\nspecial interest among topological semimetals due to the simultaneous breaking\nof both inversion and time-reversal symmetry. The concomitant absence of both\nsymmetries grants the possibility to tune the Weyl nodes chirality and to\nenhance topological effects like the chiral anomaly. In this work, we report on\nthe synthesis and compare the magnetotransport measurements of a poly- and\nsingle crystalline PrRhC2 sample. Using a remarkable and sophisticated\ntechnique, the PrRhC2 single crystal is prepared via focused ion beam cutting\nfrom the polycrystalline material. Our magnetometric and specific heat analyses\nreveal a non-collinear antiferromagnetic state below 20K, as well as\nshort-range magnetic correlations and/or magnetic fluctuations well above the\nonset of the magnetic transition. The transport measurements on the PrRhC2\nsingle crystal display an electrical resistivity peak at 3K and an anomalous\nHall effect below 6K indicative of a net magnetization component in the ordered\nstate. Furthermore, we study the angular variation of magnetoresistivities as a\nfunction of the angle between the in-plane magnetic field and the injected\nelectrical current. We find that both the transverse and the longitudinal\nresistivities exhibit fourfold angular dependencies due to higher-order terms\nin the resistivity tensor, consistent with the orthorhombic crystal symmetry of\nPrRhC2. Our experimental results may be interpreted as features of topological\nWeyl semimetallic behavior in the magnetotransport properties.",
        "positive": "Tailoring the ferromagnetic surface potential landscape by a templating\n  two-dimensional metal-organic porous network: Two-dimensional metal-organic porous networks (2D-MOPNs) have been identified\nas versatile nanoarchitectures to tailor surface electronic and magnetic\nproperties on noble metals. In this context, we propose a protocol to\nredecorate a ferromagnetic surface potential landscape using a 2D-MOPN.\nUltrathin cobalt (Co) films grown on Au(111) exhibit a well-ordered surface\ntriangular reconstruction. On the ferromagnetic surface, the adsorbed\n2,4,6-tris(4-pyridyl)-1,3,5triazine (T4PT) molecules can coordinate with the\nnative Co atoms to form a large-scale Co-T4PT porous network. The Co-T4PT\nnetwork with periodic nanocavities serves as a templating layer to reshape the\nferromagnetic surface potential. The subsequently deposited C60 molecules are\nsteered by the network porous potential and the neighboring C60 interactions.\nThe prototype of the ferromagnetic-supported 2D-MOPN is a promising template\nfor the tailoring of molecular electronic and spin properties."
    },
    {
        "anchor": "Spin/orbit moment imbalance in the near-zero moment ferromagnetic\n  semiconductor SmN: SmN is ferromagnetic below 27 K, and its net magnetic moment of 0.03 Bohr\nmagnetons per formula unit is one of the smallest magnetisations found in any\nferromagnetic material. The near-zero moment is a result of the nearly equal\nand opposing spin and orbital moments in the 6H5/2 ground state of the Sm3+\nion, which leads finally to a nearly complete cancellation for an ion in the\nSmN ferromagnetic state. Here we explore the spin alignment in this compound\nwith X-ray magnetic circular dichroism at the Sm L2,3 edges. The spectral\nshapes are in qualitative agreement with computed spectra based on an LSDA+U\n(local spin density approximation with Hubbard-U corrections) band structure,\nthough there remain differences in detail which we associate with the anomalous\nbranching ratio in rare-earth L edges. The sign of the spectra determine that\nin a magnetic field the Sm 4f spin moment aligns antiparallel to the field; the\nvery small residual moment in ferromagnetic SmN aligns with the 4f orbital\nmoment and antiparallel to the spin moment. Further measurements on very thin\n(1.5 nm) SmN layers embedded in GdN show the opposite alignment due to a strong\nGd-Sm exchange, suggesting that the SmN moment might be further reduced by\nabout 0.5 % Gd substitution.",
        "positive": "TiC lattice dynamics from ab initio calculations: Ab initio calculations and a direct method have been applied to derive the\nphonon dispersion curves and phonon density of states for the TiC crystal. The\nresults are compared and found to be in a good agreement with the experimental\nneutron scattering data. The force constants have been determined from the\nHellmann-Feynman forces induced by atomic displacements in the 2x2x2 supercell.\nThe calculated phonon density of states suggests that vibrations of Ti atoms\nform acoustic branches, whereas the motion of C atoms is confined to optic\nbranches. The elastic constants have been found using the deformation method\nand compared with the results obtained from acoustic phonon slopes."
    },
    {
        "anchor": "Parametrically Shielding Electromagnetic Fields by Nonlinear\n  Metamaterials: An analytical theory is developed for parametric interactions in metamaterial\nmultilayer structures with simultaneous nonlinear electronic and magnetic\nresponses and with near-zero refractive-index. We demonstrate theoretically\nthat electromagnetic fields of certain frequencies can be parametrically\nshielded by a nonlinear left-handed material slab, where the permittivity and\npermeability are both negative. The skin depth is tunable, and even in the\nabsence of material absorption, can be much less than the wavelength of the\nelectromagnetic field being shielded. This exotic behavior is a consequence of\nthe intricate nonlinear response in the left-handed materials and vanishing\noptical refractive-index at the pump frequency.",
        "positive": "Signatures of the Kondo effect in VSe2: VSe2 is a transition metal dichaclogenide which has a charge-density wave\ntransition that has been well studied. We report on a low-temperature upturn in\nthe resistivity and, at temperatures below this resistivity minimum, an unusual\nmagnetoresistance which is negative at low fields and positive at higher\nfields, in single crystals of VSe2. The negative magnetoresistance has a\nparabolic dependence on the magnetic field and shows little angular dependence.\nThe magnetoresistance at temperatures above the resistivity minimum is always\npositive. We interpret these results as signatures of the Kondo effect in VSe2.\nAn upturn in the susceptibility indicates the presence of interlayer V ions\nwhich can provide the localized magnetic moments required for scattering the\nconduction electrons in the Kondo effect. The low-temperature behaviour of the\nheat capacity, including a high value of gamma, along with a deviation from a\nCurie-Weiss law observed in the low-temperature magnetic susceptibility, are\nconsistent with the presence of magnetic interactions between the paramagnetic\ninterlayer V ions and a Kondo screening of these V moments."
    },
    {
        "anchor": "Demonstration of resonant inelastic X-ray scattering as a probe of\n  exciton-phonon coupling: Resonant inelastic X-ray scattering (RIXS) is a promising technique for\nobtaining electron-phonon coupling constants. However, the ability to extract\nthese coupling constants throughout the Brillouin zone for crystalline\nmaterials remains limited. To address this need, we developed a Green's\nfunction formalism to capture electron-phonon contributions to core-level\nspectroscopies without explicitly solving the full vibronic problem. Our\napproach is based on the cumulant expansion of the Green's function combined\nwith many-body theory calculated vibrational coupling constants. The\nmethodology is applied to X-ray photoemission spectroscopy, X-ray absorption\nspectroscopy (XAS), and RIXS. In the case of the XAS and RIXS, we use a\n2-particle exciton Green's function, which accounts implicitly for\nparticle-hole interference effects that have previously proved difficult. To\ndemonstrate the methodology and gain a deeper understanding of the experimental\ntechnique, we apply our formalism to small molecules, for which unambiguous\nexperimental data exist. This comparison reveals that the vibronic coupling\nconstant probed by RIXS is in fact related to exciton-phonon coupling rather\nthan electron-phonon coupling, challenging the conventional interpretation of\nthe experiment.",
        "positive": "Mass fluctuations and absorption rates in Dirac materials sensors: We study the mass fluctuations in gapped Dirac materials by treating the\nmass-term as both a continuous and discrete random variable. Gapped Dirac\nmaterials were proposed to be used as materials for Dark matter sensors. One\nthus would need to estimate the role of disorder and fluctuations on the\ninterband absorption of dark matter. We find that both continuous and discrete\nfluctuations across the sample introduce tails (e.g. Lifshitz tails) in the\ndensity of states and the interband absorption rate. We estimate the strength\nof the gap filling and discuss implications of these fluctuations on the\nperformance as sensors for Dark matter detection. The approach used in this\nwork provides a basic framework to model the disorder by any arbitrary\nmechanism on the interband absorption of Dirac material sensors."
    },
    {
        "anchor": "Overall thermomechanical properties of layered materials for energy\n  devices applications: This paper is concerned with the analysis of effective thermomechanical\nproperties of multi- layered materials of interest for solid oxide fuel cells\n(SOFC) and lithium ions batteries fabrication. The recently developed\nasymptotic homogenization procedure is applied in order to express the overall\nthermoelastic constants of the first order equivalent continuum in terms of\nmicrofluctuations functions, and these functions are obtained by the solution\nof the corresponding recursive cell problems. The effects of thermal stresses\non periodic multi-layered thermoelastic composite reproducing the\ncharacteristics of solid oxide fuel cells (SOFC-like) are studied assuming\nperiodic body forces and heat sources, and the solution derived by means of the\nasymptotic homogenization approach is compared with the results obtained by\nfinite elements analysis of the associate heterogeneous material.",
        "positive": "Nucleation-growth versus spinodal decomposition in Fe-Cr alloys: an\n  experimental verification by atom probe tomography and small angle neutron\n  scattering: Identifying the operative mode of phase separation (spinodal decomposition\n(SD) or nucleation-growth (NG)) remains a largely unexplored area of research\nin spite of its importance. The present work examines this critically in Fe-Cr\nsystem using atom probe tomography (APT) and small angle neutron scattering\n(SANS), and establishes the framework to distinguish the two different modes of\nalpha-prime phase separation in thermally aged Fe-35 at.% Cr and Fe-20 at.% Cr\nalloys. Independent APT analysis determines the mode of phase separation on the\nbasis of: (i) presence / absence of periodic chemical fluctuation through\nradial distribution function analysis; and (ii) inter-phase interface\ncharacteristics (diffuse / sharp). SANS analysis, in contrast, yields virtually\nindistinguishable correlation peaks for both the modes, which necessitates\nfurther investigation of the several different aspects of SANS profiles in the\nlight of APT results. For the first time, key features of SANS profiles have\nbeen identified that can unambiguously distinguish SD from NG in Fe-Cr system:\n(i) nature of temporal evolution of FWHM of the correlation peak; and (ii)\nappropriate value of 'gamma' for fitting with the dynamic scaling model\n('gamma'= 6 for SD, Fe-35 at.% Cr alloy; 'gamma'= 4 for NG, Fe-20 at.% Cr\nalloy)."
    },
    {
        "anchor": "Growth and Electronic Structure of Boron-Doped Graphene: The doping of graphene to tune its electronic structure is essential for its\nfurther use in carbon based electronics. Adapting strategies from classical\nsilicon based semiconductor technology, we use the incorporation of heteroatoms\nin the 2D graphene network as a straightforward way to achieve this goal. Here,\nwe report on the synthesis of boron-doped graphene on Ni(111) in a chemical\nvapor deposition process of triethylborane on the one hand and by segregation\nof boron from the bulk on the other hand. The chemical environment of boron was\ndetermined by x-ray photoelectron spectroscopy and angle resolved photoelectron\nspectroscopy was used to analyze the impact on the band structure. Doping with\nboron leads to a shift of the graphene bands to lower binding energies. The\nshift depends on the doping concentration and for a doping level of 0.3 ML a\nshift of up to 1.2 eV is observed. The experimental results are in agreement\nwith density-functional calculations. Furthermore, our calculations suggest\nthat doping with boron leads to graphene preferentially adsorbed in the top-fcc\ngeometry, since the boron atoms in the graphene lattice are then adsorbed at\nsubstrate fcc-hollow sites. The smaller adsorption distance of boron compared\nto carbon leads to a bending of the graphene sheet in the vicinity of the boron\natoms. By comparing calculations of doped and undoped graphene on Ni(111), as\nwell as the respective free-standing cases, we are able to distinguish between\nthe effects that doping and adsorption have on the band structure of graphene.\nBoth, doping and bonding to the surface, result in opposing shifts on the\ngraphene bands.",
        "positive": "Borophene as an anode material for Ca, Mg, Na or Li ion storage: A\n  first-principle study: Borophene, the boron atom analogue to graphene, being atomic thick have been\njust recently experimentally fabricated. In this work, we employ\nfirst-principles density functional theory calculations to investigate the\ninteraction of Ca, Mg, Na or Li atoms with single-layer and free-standing\nborophene. We first identified the most stable binding sites and their\ncorresponding binding energies as well and then we gradually increased the ions\nconcentration. Our calculations predict strong binding energies of around 4.03\neV, 2.09 eV, 2.92 eV and 3.28 eV between the borophene substrate and Ca, Mg, Na\nor Li ions, respectively. We found that the binding energy generally decreases\nby increasing the ions content. Using the Bader charge analysis, we evaluate\nthe charge transfer between the adatoms and the borophene sheet. Our\ninvestigation proposes the borophene as a 2D material with a remarkably high\ncapacity of around 800 mAh/g, 1960 mAh/g, 1380 mAh/g and 1720 mAh/g for Ca, Mg,\nNa or Li ions storage, respectively. This study can be useful for the possible\napplication of borophene for the rechargeable ion batteries."
    },
    {
        "anchor": "Vibrational zero point energy for H-doped Silicon: Most of the studies addressed to computations of hydrogen parameters in\nsemiconductor systems, such as silicon, are performed at zero temperature T=0 K\nand do not account for contribution of vibrational zero point energy (ZPE). For\nlight weight atoms such as hydrogen (H), however, magnitude of this parameter\nmight be not negligible. This work is devoted to clarify the importance of\naccounting the zero-point vibrations when analyzing hydrogen behavior in\nsilicon and its effect on silicon electronic properties. For this, we estimate\nthe ZPE for different locations and charge states of H in Si. We show that the\nmain contribution to the ZPE is coming from vibrations along the Si-H bonds\nwhereas contributions from other Si atoms apart from the direct Si-H bonds play\nno role. It is demonstrated that accounting the ZPE reduces the hydrogen\nformation energy by ~0.17 eV meaning that neglecting ZPE at low temperatures\none can underestimate hydrogen solubility by few orders of magnitude. In\ncontrast, the effect of the ZPE on the ionization energy of H in Si is\nnegligible. The results can have important implications for characterization of\nvibrational properties of Si by inelastic neutron scattering, as well as for\ntheoretical estimations of H concentration in Si.",
        "positive": "Quasi-harmonic thermoelasticity of palladium, platinum, copper, and gold\n  from first principles: We calculate the temperature-dependent elastic constants of palladium,\nplatinum, copper and gold within the quasi-harmonic approximation using a\nfirst-principles approach and evaluating numerically the second derivatives of\nthe Helmholtz free-energy with respect to strain at the minimum of the\nfree-energy itself. We find an overall good agreement with the experimental\ndata although the anomalies of palladium and platinum reported at room\ntemperature are not reproduced. The contribution of electronic excitations is\nalso investigated: we find that it is non-negligible for the $C_{44}$ elastic\nconstants of palladium and platinum while it is irrelevant in the other cases.\nIts effect is not sufficient to explain the details of the anomalies found by\nexperiments, not even when, in the case of platinum, we take into account the\nelectron-phonon interaction. Lastly, the effect of the exchange and correlation\nfunctional is addressed and it is found that it is important at T=0 K, while\nall functionals give similar temperature dependencies."
    },
    {
        "anchor": "Pressure-induced non-monotonic crossover of steady relaxation dynamics\n  in a metallic glass: Relaxation dynamics, as a key to understand glass formation and glassy\nproperties, remains an elusive and challenging issue in condensed matter\nphysics. In this work, in situ high-pressure synchrotron high-energy x-ray\nphoton correlation spectroscopy has been developed to probe the atomic-scale\nrelaxation dynamics of a cerium-based metallic glass during compression.\nAlthough the sample density continuously increases, the collective atomic\nmotion initially slows down as generally expected and then counter-intuitively\naccelerates with further compression (density increase), showing an unusual\nnon-monotonic pressure-induced steady relaxation dynamics crossover at ~3 GPa.\nFurthermore, by combining in situ high-pressure synchrotron x-ray diffraction,\nthe relaxation dynamics anomaly is evidenced to closely correlate with the\ndramatic changes in local atomic structures during compression, rather than\nmonotonically scaling with either sample density or overall stress level. These\nfindings could provide new insight into relaxation dynamics and their\nrelationship with local atomic structures of glasses.",
        "positive": "Topological classification for intersection singularities of exceptional\n  surfaces in pseudo-Hermitian systems: Exceptional points play a pivotal role in the topology of non-Hermitian\nsystems, and significant advances have been made in classifying exceptional\npoints and exploring the associated phenomena. Exceptional surfaces, which are\nhypersurfaces of exceptional degeneracies in parameter space, can support\nhypersurface singularities, such as cusps, intersections and swallowtail\ncatastrophes. Here we topologically classify the intersection singularity of\nexceptional surfaces for a generic pseudo-Hermitian system with parity-time\nsymmetry. By constructing the quotient space under equivalence relations of\neigenstates, we reveal that the topology of such gapless structures can be\ndescribed by a non-Abelian free group on three generators. Importantly, the\nclassification predicts a new kind of non-Hermitian gapless topological phase\nand can systematically explain how the exceptional surfaces and their\nintersections evolve under perturbations with symmetries preserved. Our work\nopens a new pathway for designing systems with robust topological phases, and\nprovides inspiration for applications such as sensing and lasing which can\nutilize the special properties inherent in exceptional surfaces and\nintersections."
    },
    {
        "anchor": "Morphologies and kinetics of a dewetting ultrathin solid film: The surface evolution model based on geometric partial differential equation\nis used to numerically study the kinetics of dewetting and dynamic morphologies\nfor the localized pinhole defect in the surface of the ultrathin solid film\nwith the strongly anisotropic surface energy. Depending on parameters such as\nthe initial depth and width of the pinole, the strength of the attractive\nsubstrate potential and the strength of the surface energy anisotropy, the\npinhole may either extend to the substrate and thus rupture the film, or evolve\nto the quasiequilibrium shape while the rest of the film surface undergoes\nphase separation into a hill-and-valley structure followed by coarsening.\nOverhanging (non-graph) morphologies are possible for deep, narrow (slit-like)\npinholes.",
        "positive": "Beam propagation in finite size photonic crystals and metamaterials: The recent interest in the imaging possibilities of photonic crystals\n(superlensing, superprism, optical mirages etc...) call for a detailed analysis\nof beam propagation inside a finite periodic structure. In this paper, an\nanswer to the question \"where does the beam emerge?\" is given. Contrarily to\ncommon knowledge, it is not always true that the shift of a beam is given by\nthe normal to the dispersion curve. This phenomenon is explained in terms of\nevanescent waves and a renormalized diagram that gives the correct direction is\ngiven."
    },
    {
        "anchor": "CMOS-compatible controlled hyperdoping of silicon nanowires: Hyperdoping consists of the intentional introduction of deep-level dopants\ninto a semiconductor in excess of equilibrium concentrations. This causes a\nbroadening of dopant energy levels into an intermediate band between the\nvalence and conduction bands.[1,2] Recently, bulk Si hyperdoped with chalcogens\nor transition metals has been demonstrated to be an appropriate\nintermediate-band material for Si-based short-wavelength infrared\nphotodetectors.[3-5] Intermediate-band nanowires could potentially be used\ninstead of bulk materials to overcome the Shockley-Queisser limit and to\nimprove efficiency in solar cells,[6-9] but fundamental scientific questions in\nhyperdoping Si nanowires require experimental verification. The development of\na method for obtaining controlled hyperdoping levels at the nanoscale\nconcomitant with the electrical activation of dopants is, therefore, vital to\nunderstanding these issues. Here, we show a CMOS-compatible technique based on\nnon-equilibrium processing for the controlled doping of Si at the nanoscale\nwith dopant concentrations several orders of magnitude greater than the\nequilibrium solid solubility. Through the nanoscale spatially controlled\nimplantation of dopants, and a bottom-up template-assisted solid phase\nrecrystallization of the nanowires with the use of millisecond-flash lamp\nannealing, we form Se-hyperdoped Si/SiO2 core/shell nanowires that have a\nroom-temperature sub-band gap optoelectronic photoresponse when configured as a\nphotoconductor device.",
        "positive": "Colloidal Lead Iodide Nanorings: Colloidal chemistry of nanomaterials experienced a tremendous development in\nthe last decades. In the course of the journey 0D nanoparticles, 1D nanowires,\nand 2D nanosheets have been synthesized. They have in common to possess a\nsimple topology. We present a colloidal synthesis strategy for lead iodide\nnanorings, with a non-trivial topology. First, two-dimensional structures were\nsynthesized in nonanoic acid as the sole solvent. Subsequently, they underwent\nan etching process in the presence of trioctylphosphine, which determines the\nsize of the hole in the ring structure. We propose a mechanism for the\nformation of lead iodide nanosheets which also explains the etching of the\ntwo-dimensional structures starting from the inside, leading to nanorings. In\naddition, we demonstrate a possible application of the as-prepared nanorings in\nphotodetectors. These devices are characterized by a fast response, high gain\nvalues, and a linear relation between photocurrent and incident light power\nintensity over a large range. The synthesis approach allows for inexpensive\nlarge-scale production of nanorings with tunable properties."
    },
    {
        "anchor": "Assessment of the GW approximation using Hubbard chains: We investigate the performance of the GW approximation by comparison to exact\nresults for small model systems. The role of the chemical potentials in Dyson's\nequation as well as the consequences of numerical resonance broadening are\nexamined, and we show how a proper treatment can improve computational\nimplementations of many-body perturbation theory in general. GW and\nexchange-only calculations are performed over a wide range of fractional band\nfillings and correlation strengths. We thus identify the physical situations\nwhere these schemes are applicable.",
        "positive": "Nonlinear electric field effect on perpendicular magnetic anisotropy in\n  Fe/MgO interfaces: The electric field effect on magnetic anisotropy was studied in an ultrathin\nFe(001) monocrystalline layer sandwiched between Cr buffer and MgO tunnel\nbarrier layers, mainly through post-annealing temperature and measurement\ntemperature dependences. A large coefficient of the electric field effect of\nmore than 200 fJ/Vm was observed in the negative range of electric field, as\nwell as an areal energy density of perpendicular magnetic anisotropy (PMA) of\naround 600 uJ/m2. More interestingly, nonlinear behavior, giving rise to a\nlocal minimum around +100 mV/nm, was observed in the electric field dependence\nof magnetic anisotropy, being independent of the post-annealing and measurement\ntemperatures. The insensitivity to both the interface conditions and the\ntemperature of the system suggests that the nonlinear behavior is attributed to\nan intrinsic origin such as an inherent electronic structure in the Fe/MgO\ninterface. The present study can contribute to the progress in theoretical\nstudies, such as ab initio calculations, on the mechanism of the electric field\neffect on PMA."
    },
    {
        "anchor": "Evidence of defect-induced ferromagnetism in ZnFe$_{2}$O$_{4}$ thin\n  films: X-ray absorption near-edge and grazing incidence X-ray fluorescence\nspectroscopy are employed to investigate the electronic structure of\nZnFe$_{2}$O$_{4}$ thin films. The spectroscopy techniques are used to determine\nthe non-equilibrium cation site occupancy as a function of depth and oxygen\npressure during deposition and its effects on the magnetic properties. It is\nfound that low deposition pressures below 10$^{-3}$ mbar cause iron\nsuperoccupation of tetrahedral sites without Zn$^{2+}$ inversion, resulting in\nan ordered magnetic phase with high room temperature magnetic moment.",
        "positive": "Phase Transition of Na3SbS4 Superionic Conductor and Its Impact on Ion\n  Transport: In this work, a comprehensive research coupling experiment and computation\nhas been performed to understand the phase transition of Na3SbS4 and to\nsynthesize cubic Na3SbS4 (c-Na3SbS4), a high temperature phase of Na3SbS4 that\nis difficult to be preserved from high temperature. The formation of c-Na3SbS4\nis verified by Rietveld refinement and electrochemical impedance spectroscopy.\nBoth experiment and theoretical calculation reveal that the ionic conductivity\nof c-Na3SbS4 is higher than that of t-Na3SbS4, though the values are in the\nsame order of magnitude. Both structures allow fast ion transport."
    },
    {
        "anchor": "Dielectric spectra of a new relaxor ferroelectric system Ba2LnTi2Nb3O15\n  (Ln=La, Nd): New relaxor ferroelectric system has been synthesized. BLTN exhibits a\nsmeared maximum of permittivity, characteristic of classic relaxor behaviour,\nwith a peak shift from 185 K at 100 Hz to 300 K at 1 GHz. BNTN undergoes a\nfirst order ferroelectric phase transition at 389 K and BLNTN exhibits both a\nferroelectric phase transition at 274 K and relaxor behaviour at higher\ntemperatures.",
        "positive": "Layered transition metal dichalcogenides: promising near-lattice-matched\n  substrates for GaN growth: Most III-nitride semiconductors are grown on non-lattice-matched substrates\nlike sapphire or silicon due to the extreme difficulty of obtaining a native\nGaN substrate. We show that several layered transition-metal dichalcogenides\nare closely lattice matched to GaN and report the growth of GaN on a range of\nsuch layered materials. We report detailed studies of the growth of GaN on\nmechanically-exfoliated flakes WS$_2$ and MoS$_2$ by metalorganic vapour phase\nepitaxy. Structural and optical characterization show that strain-free,\nsingle-crystal islands of GaN are obtained on the underlying chalcogenide\nflakes. We obtain strong near-band-edge emission from these layers, and analyse\ntheir temperature-dependent photoluminescence properties. We also report a\nproof-of-concept demonstration of large-area epitaxial growth of GaN on CVD\nMoS$_2$. Our results show that the transition-metal dichalcogenides can serve\nas novel near-lattice-matched substrates for nitride growth."
    },
    {
        "anchor": "Application of elastostatic Green function tensor technique to\n  electrostriction in cubic, hexagonal and orthorhombic crystals: The elastostatic Green function tensor approach, which was recently used to\ntreat electrostriction in numerical simulation of domain structure formation in\ncubic ferroelectrics, is reviewed and extended to the crystals of hexagonal and\northorhombic symmetry. The tensorial kernels appearing in the expressions for\neffective nonlocal interaction of electrostrictive origin are derived\nexplicitly and their physical meaning is illustrated on simple examples. It is\nargued that the bilinear coupling between the polarization gradients and\nelastic strain should be systematically included in the Ginzburg-Landau free\nenergy expansion of electrostrictive materials.",
        "positive": "Optoelectronic and thermoelectric properties of Ba3DN (D = Sb, Bi): A\n  DFT investigation: We have investigated the optoelectronic and thermoelectric properties of\nhexagonal antiperovskites Ba$_3$DN (D = Sb, Bi) using DFT calculations. The\ncalculated equilibrium lattice parameters of both compounds are in good\nagreement with the available data. The calculated electronic structures\nindicate that they are direct bandgap semiconductors and the values of bandgaps\nare 1.35 and 1.33 eV for Ba3SbN and Ba3BiN, respectively. The inclusion of the\nspin-orbit effect split the conduction bands and the band gap of Ba$_3$BiN is\nmuch reduced. These two compounds have a high absorption coefficient, notably\nhigher than that for GaAs and close to that for silicon. The obtained static\nrefractive index is ~2.8 and 3.26, for Ba$_3$SbN and Ba$_3$BiN, respectively.\nWe predict that both materials are suitable for a high-efficiency solar cell.\nBoth compounds exhibit a high Seebeck coefficient and high power factor. Our\nanalysis predicts that the studied materials are potential candidates in\nthermoelectric device applications."
    },
    {
        "anchor": "Kinetics of random sequential adsorption of nearly spherically symmetric\n  particles: Kinetics of random sequential adsorption (RSA) of spheres on flat,\ntwo-dimensional surfaces is governed by a power law with exponent $-1/2$. The\nstudy has shown that for RSA of nearly spherically symmetric particles this\nexponent is $-1/3$, whereas other characteristics typically measured in RSA\nsimulations approach values known for spheres with the increase of symmetry of\nthe particles.",
        "positive": "Au/TiO2(110) interfacial reconstruction stability from ab initio: We determine the stability and properties of interfaces of low-index Au\nsurfaces adhered to TiO2(110), using density functional theory energy density\ncalculations. We consider Au(100) and Au(111) epitaxies on rutile TiO2(110)\nsurface, as observed in experiments. For each epitaxy, we consider several\ndifferent interfaces: Au(111)//TiO2(110) and Au(100)//TiO2(110), with and\nwithout bridging oxygen, Au(111) on 1x2 added-row TiO2(110) reconstruction, and\nAu(111) on a proposed 1x2 TiO reconstruction. The density functional theory\nenergy density method computes the energy changes on each of the atoms while\nforming the interface, and evaluates the work of adhesion to determine the\nequilibrium interfacial structure."
    },
    {
        "anchor": "Interplay between structure and magnetism in the low-dimensional spin\n  system $K(C_8H_{16}O_4)_2CuCl_3{*}H_2O$: Materials based on a crown ether complex together with magnetic ions,\nespecially Cu(II), can be used to synthesize new low dimesional quantum spin\nsystems. We have prepared the new crown ether complex\nDi-\\mu-chloro-bis(12-crown-4)-aquqdichloro-copper(II)-potassium,\n$K(C_8H_{16}O_4)_2CuCl_3{*}H_2O$ (1), determined its structure, and analyzed\nits magnetic properties. Complex (1) has a monoclinic structure and\ncrystallizes in space group $P2_1/n$ with the lattice parameters of\n$a=9.5976(5)\\r{A}$, $b=11.9814\\r{A}, c=21.8713\\r{A}$ and\n$\\beta=100.945(4)\\deg$. The magnetic properties of this compound have been\ninvestigated in the temperature range 1.8 K - 300 K. The magnetic\nsusceptibility shows a maximum at 23 K, but no 3-D long range magnetic order\ndown to 1.8 K. The S=1/2 Cu(II) ions form antiferromagnetically coupled dimers\nwith Cu-Cl distances of $2.2554(8)\\r{A}$ and $4.683(6)\\r{A}$, and a Cu-Cl-Cu\nangle of $115.12(2)\\deg$ with $2J_{dimer}=-2.96meV (-23.78 cm^{-1})$. The\ninfluence of $H_2O$ on the Cl-Cu-Cl exchange path is analyzed. Our results show\nthat the values of the singlet-triplet splitting are increasing considering\n$H_2O$ molecules in the bridging interaction. This is supported by Density\nfunctional theory (DFT) calculations of coupling constants with Perdew and Wang\n(PWC), Perdew, Burke and Ernzenrhof (PBE) and strongly constrained and\nappropriately normed (SCAN) exchange-correlation function show excellent\nagreement for the studied compound.",
        "positive": "Remote gate control of topological transitions in moir\u00e9\n  superlattices via cavity vacuum fields: Placed in cavity resonators with three-dimensionally confined electromagnetic\nwave, the interaction between quasiparticles in solids can be induced by\nexchanging virtual cavity photons, which can have a non-local characteristic.\nHere we investigate the possibility of utilizing this nonlocality to realize\nthe remote control of the topological transition in mesoscopic moir\\'{e}\nsuperlattices at full filling (one electron/hole per supercell) embedded in a\nsplit-ring terahertz electromagnetic resonator. We show that gate tuning one\nmoir\\'{e} superlattice can remotely drive a topological band inversion in\nanother moir\\'{e} superlattice not in contact but embedded in the same cavity.\nOur study of remote on/off switching of a topological transition provides a\nnovel paradigm for the control of material properties via cavity vacuum fields."
    },
    {
        "anchor": "Band structure of hydrogenated silicene on Ag(111): Evidence for\n  silicane: In the case of graphene, hydrogenation removes the conductivity due to the\nbands forming the Dirac cone by opening up a band gap. This type of chemical\nfunctionalization is of utmost importance for electronic applications. As\npredicted by theoretical studies, a similar change of the band structure is\nexpected for silicene, the closest analogue to graphene. We here report a study\nof the atomic and electronic structures of hydrogenated silicene, so called\nsilicane. The ($\\small 2\\sqrt{3} \\times 2\\sqrt{3}$) phase of silicene on\nAg(111) was used in this study since it can be formed homogeneously across the\nentire surface of the Ag substrate. Low energy electron diffraction and\nscanning tunneling microscopy data clearly show that hydrogenation changes the\nstructure of silicene on Ag(111) resulting in a (1 $\\times$ 1) periodicity with\nrespect to the silicene lattice. The hydrogenated silicene also exhibits a\nquasi-regular ($\\small 2\\sqrt{3} \\times 2\\sqrt{3}$)-like arrangement of\nvacancies. Angle resolved photoelectron spectroscopy revealed two dispersive\nbands which can be unambiguously assigned to silicane. The common top of these\nbands is located at $\\small \\backsim$ 0.9 eV below the Fermi level. We find\nthat the experimental bands are closely reproduced by the theoretical band\nstructure of free standing silicane with H adsorbed on the upper hexagonal\nsub-lattice of silicene.",
        "positive": "Giant interfacial perpendicular magnetic anisotropy in MgO/CoFe/capping\n  layer structures: Magnetic tunnel junction (MTJ) based on CoFeB/MgO/CoFeB structures is of\ngreat interest due to its application in the spin-transfer-torque magnetic\nrandom access memory (STT-MRAM). Large interfacial perpendicular magnetic\nanisotropy (PMA) is required to achieve high thermal stability. Here we use\nfirst-principles calculations to investigate the magnetic anisotropy energy\n(MAE) of MgO/CoFe/capping layer structures, where the capping materials include\n5d metals Hf, Ta, Re, Os, Ir, Pt, Au and 6p metals Tl, Pb, Bi. We demonstrate\nthat it is feasible to enhance PMA by using proper capping materials.\nRelatively large PMA is found in the structures with capping materials of Hf,\nTa, Os, Ir and Pb. More importantly, the MgO/CoFe/Bi structure gives rise to\ngiant PMA (6.09 mJ/m2), which is about three times larger than that of the\nMgO/CoFe/Ta structure. The origin of the MAE is elucidated by examining the\ncontributions to MAE from each atomic layer and orbital. These findings provide\na comprehensive understanding of the PMA and point towards the possibility to\nachieve advanced-node STT-MRAM with high thermal stability."
    },
    {
        "anchor": "First non-icosahedral boron allotrope synthesized at high pressure and\n  high temperature: Theoretical predictions of pressure-induced phase transformations often\nbecome long-standing enigmas because of limitations of contemporary available\nexperimental possibilities. Hitherto the existence of a non-icosahedral boron\nallotrope has been one of them. Here we report on the first non-icosahedral\nboron allotrope, which we denoted as {\\zeta}-B, with the orthorhombic\n{\\alpha}-Ga-type structure (space group Cmce) synthesized in a diamond anvil\ncell at extreme high-pressure high-temperature conditions (115 GPa and 2100 K).\nThe structure of {\\zeta}-B was solved using single-crystal synchrotron X-ray\ndiffraction and its compressional behavior was studied in the range of very\nhigh pressures (115 GPa to 135 GPa). Experimental validation of theoretical\npredictions reveals the degree of our up-to-date comprehension of condensed\nmatter and promotes further development of the solid state physics and\nchemistry.",
        "positive": "Gigantic directional asymmetry of luminescence in multiferroic CuB2O4: We report direction dependent luminescence (DDL), i.e., the asymmetry in the\nluminescence intensity between the opposite directions of the emission, in\nmultiferroic CuB2O4. Although it is well known that the optical constants can\nchange with the reversal of the propagation direction of light in multiferroic\nmaterials, the largest asymmetry in the luminescence intensity was 0.5 % so\nfar. We have performed a measurement of photoluminescence with a He-Ne laser\nirradiation (633 nm). The luminescence intensity changes by about 70 % with the\nreversal of the magnetic field due to the interference between the electric\ndipole and magnetic dipole transitions. We also demonstrate the imaging of the\ncanted antiferromagnetic domain structure of (Cu,Ni)B2O4 by using the large\nDDL."
    },
    {
        "anchor": "Bounds on Effective Dynamic Properties of Elastic Composites: We present general, computable, improvable, and rigorous bounds for the total\nenergy of a finite heterogeneous volume element or a periodically distributed\nunit cell of an elastic composite of any known distribution of inhomogeneities\nof any geometry and elasticity, undergoing a harmonic motion at a fixed\nfrequency or supporting a single-frequency Bloch-form elastic wave of a given\nwave-vector. These bounds are rigorously valid for \\emph{any consistent\nboundary conditions} that produce in the finite sample or in the unit cell,\neither a common average strain or a common average momentum. No other\nrestrictions are imposed. We do not assume statistical homogeneity or isotropy.\nOur approach is based on the Hashin-Shtrikman (1962) bounds in elastostatics,\nwhich have been shown to provide strict bounds for the overall elastic moduli\ncommonly defined (or actually measured) using uniform boundary tractions and/or\nlinear boundary displacements; i.e., boundary data corresponding to the overall\nuniform stress and/or uniform strain conditions. Here we present strict bounds\nfor the dynamic frequency-dependent constitutive parameters of the composite\nand give explicit expressions for a direct calculation of these bounds.",
        "positive": "Global band topology of simple and double Dirac-point (semi-)metals: We combine space group representation theory together with scanning of closed\nsubdomains of the Brillouin zone with Wilson loops to algebraically determine\nglobal band structure topology. Considering space group #19 as a case study, we\nshow that the energy ordering of the irreducible representations at the\nhigh-symmetry points $\\{\\Gamma,S,T,U\\}$ fully determines the global band\ntopology, with all topological classes characterized through their simple and\ndouble Dirac-points."
    },
    {
        "anchor": "Optical properties of high pressure liquid hydrogen across molecular\n  dissociation: Optical properties of compressed fluid hydrogen in the region where\ndissociation and metallization is observed are computed by ab-initio methods\nand compared to recent experimental results. We confirm that above 3000 K both\nprocesses are continuous while below 1500K the first order phase transition is\naccompanied by a discontinuity of the DC conductivity and the thermal\nconductivity, while both the reflectivity and absorption coefficient vary\nrapidly but continuously. Our results support the recent analysis of NIF\nexperiments (P. Celliers et al, Science 361, 677-682 (2018)) which assigned the\ninception of metallization to pressures where the reflectivity is about 0.3.\nOur results also support the conclusion that the temperature plateau seen in\nlaser-heated DAC experiments at temperatures higher than 1500 K corresponds to\nthe onset of of optical absorption, not to the phase transition.",
        "positive": "Generalised boundary conditions for hydrogen transport at crack tips: We present a generalised framework for resolving the\nelectrochemistry-diffusion interface and modelling hydrogen transport near a\ncrack tip. The adsorption and absorption kinetics are captured by means of\nNeumann-type generalised boundary conditions. The diffusion model includes the\nrole of trapping, with a constant or evolving trap density, and the influence\nof the hydrostatic stress. Both conventional plasticity and strain gradient\nplasticity are used to model the mechanical behaviour of the solid. Notable\ndifferences are found in the estimated crack tip hydrogen concentrations when\ncomparing with the common procedure of prescribing a constant hydrogen\nconcentration at the crack surfaces."
    },
    {
        "anchor": "Prediction of unconventional magnetism in doped FeSb2: It is commonly believed that in typical collinear antiferromagnets, with no\nnet magnetization, the energy bands are spin-(Kramers-degenerate. The opposite\ncase is usually associated with a global time-reversal symmetry breaking (e.g.,\nvia ferro(i)magnetism), or with the spin-orbit interaction is combined with the\nbroken spatial inversion symmetry. Recently, another type of spin splitting was\ndemonstrated to emerge in some fully compensated by symmetry, nonrelativistic,\ncollinear magnets, and not even necessarily non-centrosymmetric. These\nmaterials feature non-zero spin density staggered not only in real, but also in\nmomentum space. This duality results in a combination of characteristics\ntypical of ferro- and antiferromagnets. Here we discuss this novel concept in\napplication to a well-known semiconductor, FeSb2, and predict that upon certain\nalloying it becomes magnetic, and features such magnetic duality. The\ncalculated energy bands split antisymmetrically with respect to spin degenerate\nnodal surfaces (and not nodal points, as in the case of spin-orbit splitting.\nThis combination of a large (0.2 eV) spin splitting, compensated net\nmagnetization and metallic ground-state, and a particular magnetic easy axis\ngenerate a large anomalous Hall conductivity (~150 S/cm) and a sizable\nmagneto-optical Kerr effect, all deemed to be hallmarks of nonzero net\nmagnetization. We identify a large contribution to the anomalous response\noriginating from the spin-orbit interaction gapped anti-Kramers nodal surfaces,\na mechanism distinct from the nodal lines and Weyl {\\it points} in\nferromagnets.",
        "positive": "Sb concentration dependent structural and resistive properties of\n  polycrystalline Bi-Sb alloys: Polycrystalline Bi-Sb alloys have been synthesized over a wide range of\nantimony concentration (8 at% to 20 at%) by solid state reaction method. In\ndepth structural analysis using X-Ray diffraction (XRD) and temperature\ndependent resistivity measurement of synthesized samples have been performed.\nXRD data confirmed single phase nature of polycrystalline samples and revealed\nthat complete solid solution is formed between bismuth and antimony. Rietveld\nrefinement technique, utilizing MAUD software, has been used to perform detail\nstructural analysis of the samples and lattice parameters of synthesized Bi-Sb\nalloys have been estimated. Lattice parameter and unit cell volume decreases\nmonotonically with increasing antimony content. The variation of lattice\nparameters with antimony concentration depicts a distinct slope change beyond\n12 at% Sb content sample. Band gap has been estimated from the thermal\nvariation of resistivity data, with the 12% Sb content sample showing maximum\nvalue. It has been observed that, with increasing antimony concentration the\ntransition from direct to indirect gap semiconductor is intimately related to\nthe variation of the estimated lattice parameters. Band diagram for the\npolycrystalline Bi-Sb alloy system has also been proposed."
    },
    {
        "anchor": "Overhauser frequency shifts in semiconductor nanostructures: We calculate the Overhauser frequency shifts in semiconductor nanostructures\nresulting from the hyperfine interaction between nonequilibrium electronic\nspins and nuclear spins. The frequency shifts depend on the electronic local\ndensity of states and spin polarization as well as the electronic and nuclear\nspin relaxation mechanisms. Unlike previous calculations, our method accounts\nfor the electron confinement in low dimensional semiconductor nanostructures,\nresulting in both nuclear spin polarizations and Overhauser shifts that are\nstrongly dependent on position. Our results explain previously puzzling\nmeasurements of Overhauser shifts in an Al$_x$Ga$_{1-x}$As parabolic quantum\nwell by showing the connection between the electron spin lifetime and the\nfrequency shifts.",
        "positive": "Measurement of specific contact resistivity using scanning voltage\n  probes: Specific contact resistivity measurements have conventionally been heavy in\nboth fabrication and simulation/calculation in order to account for complicated\ngeometries and other effects such as parasitic resistance. We propose a simpler\ngeometry to deliver current, and the use of a scanning voltage probe to sense\nthe potential variation along the sample surface, from which the specific\ncontact resistivity can be straightforwardly deduced. We demonstrate an\nanalytical example in the case where both materials are thin films.\nExperimental data with a scanning Kelvin probe measurement on graphene from the\nliterature corroborates our model calculation."
    },
    {
        "anchor": "Magnetization and EPR studies of the single molecule magnet Ni$_4$ with\n  integrated sensors: Integrated magnetic sensors that allow simultaneous EPR and magnetization\nmeasurements have been developed to study single molecule magnets. A high\nfrequency microstrip resonator has been integrated with a micro-Hall effect\nmagnetometer. EPR spectroscopy is used to determine the energy splitting\nbetween the low lying spin-states of a Ni$_4$ single crystal, with an S=4\nground state, as a function of applied fields, both longitudinal and transverse\nto the easy axis at 0.4 K. Concurrent magnetization measurements show changes\nin spin-population associated with microwave absorption. Such studies enable\ndetermination of the energy relaxation time of the spin system.",
        "positive": "Graphene-Wrapped Sulfur Particles as a Rechargeable\n  Lithium-Sulfur-Battery Cathode Material with High Capacity and Cycling\n  Stability: We report the synthesis of a graphene-sulfur composite material by wrapping\npolyethyleneglycol (PEG) coated submicron sulfur particles with mildly oxidized\ngraphene oxide sheets decorated by carbon black nanoparticles. The PEG and\ngraphene coating layers are important to accommodating volume expansion of the\ncoated sulfur particles during discharge, trapping soluble polysulfide\nintermediates and rendering the sulfur particles electrically conducting. The\nresulting graphene-sulfur composite showed high and stable specific capacities\nup to ~600mAh/g over more than 100 cycles, representing a promising cathode\nmaterial for rechargeable lithium batteries with high energy density."
    },
    {
        "anchor": "Neutralization of low energy Na$^{+}$ scattered from InAs(001): The neutralization probability of low energy Na$^{+}$ ions scattered from In-\nand As-rich InAs(001) surfaces is measured by time-of-flight spectroscopy. It\nis found that the neutralization probability for projectiles scattered from As\nsites is larger than from In sites for both types of surfaces. A modification\nof the resonant charge transfer model is proposed in which a freezing contour\nthat follows the atomic structure is combined with molecular dynamics and\ndensity functional theory. Together, these approaches show that the\nneutralization of alkali projectiles scattered from a compound solid material\nis determined by multiple factors, particularly the surface atomic and\nelectronic structures. This model is applicable to any system in which the\nsurface potential is inhomogeneous, such as compound materials and\nadsorbate-covered surfaces.",
        "positive": "Simple Cubic Carbon Phase C21-sc: A Promising Superhard Carbon Conductor: Traditionally, all superhard carbon phases including diamond are electric\ninsulators and all conductive carbon phases including graphite are mechanically\nsoft. Based on first-principles calculation results, we report a superhard but\nconductive carbon phase C21-sc which can be obtained through increasing the sp3\nbonds in the previously proposed soft and conductive phase C20-sc (Phys. Rev. B\n74, 172101 2006). We also show that further increase of sp3 bonds in C21-sc\nresults in a superhard and insulating phase C22-sc with sp3 bonds only. With\nC20-sc, C21-sc, C22-sc and graphite, the X-ray diffraction peaks from the\nunidentified carbon material synthesized by compressing the mixture of\ntetracyanoethylene and carbon black (Carbon, 41, 1309, 2003) can be understood.\nIn view of its positive stability, superhard and conductive features, and the\nstrong possibility of existence in previous experiments, C21-sc is a promising\nmulti-functional material with potential applications in extreme conditions."
    },
    {
        "anchor": "CO adsorption on Cu(211) surface: first principle and STM study: Chemisorption of CO on the stepped Cu(211) surface is studied within\nab-initio density functional theory (DFT) and scanning tunneling microscopy\n(STM) imaging as well as manipulation experiments. Theoretically we focus on\nthe experimentally observed ordered (2x1) and (3x1) CO-phases at coverages 1/3,\n1/2 and 2/3 monolayer (ML). To obtain also information for isolated CO\nmolecules found randomly distributed at low coverages, we also performed\ncalculations for a hypothetical (3x1) phase with 1/3 ML. The adsorption\ngeometry, the stretching frequencies, the work functions and adsorption\nenergies of the CO molecules in the different phases are presented and compared\nto experimental data. Initially and up to a coverage of 1/2 ML CO adsorbs\nupright on the on-top sites at step edge atoms. Determining the most favorable\nadsorption geometry for the 2/3 ML ordered phase turned out to be nontrivial\nboth from the experimental and the theoretical point of view. Experimentally,\nboth top-bridge and top-top configurations were reported, whereby only the\ntop-top arrangement was firmly established. The calculated adsorption energies\nand the stretching frequencies favor the top-bridge configuration. The possible\nexistence of both configurations at 2/3 ML is critically discussed on the basis\nof the presently accessible experimental and theoretical data. In addition, we\npresent observations of STM manipulation experiments and corresponding\ntheoretical results, which show that CO adsorbed on-top of a single Cu-adatom,\nwhich is manipulated to a location close to the lower step edge, is stronger\nbound than CO on-top of a step edge atom.",
        "positive": "FORC and Micromagnetism Approach to the Domain Structure of Cobalt\n  Antidot Arrays: We study the influence of the porosity on the domain structure of cobalt\nantidots thin films with controlled and circular defects of 20, 40 and 60 nm of\ndiameter. Micromagnetic simulations, combined with First-order reversal curves\nanalysis of classical magnetometry measurements, have been used to track the\nevolution of the magnetic domain configurations. The found coercivity\nenhancement with the increase of the pore diameter is correlated to the domain\nreversibility. Moreover, we found that when the pores diameter increases the\ndomain-domain interactions become dominant."
    },
    {
        "anchor": "Dislocation loops growth and radiation growth in neutron irradiated\n  Zr-Nb alloys: rate theory modelling: A generalized model to study dislocation loops growth in irradiated binary\nZr-based alloys is presented. It takes into account temperature effects,\nefficiencies of loops to absorb point defects dependent on the loop size, an\ninfluence of locality of grain boundary sink strength, and concentration of the\nalloying element. This model is used to describe the dynamics of loop radii\ngrowth in zirconium-niobium alloys under neutron irradiation at reactor\nconditions. A growth of both loop radii and strains is studied at different\ngrain sizes, location from grain boundaries, and concentration of niobium. It\nis shown that locality of grain boundary sinks results in a non-uniform\ndeformation of the crystal inside the grains. Additionally, an introduction of\nniobium as an alloying element decreases the loop radii but promotes the growth\nof local strains inside the grains.",
        "positive": "Excited-state relaxations and Franck-Condon shift in Si quantum dots: Excited-state relaxations in molecules are responsible for a red shift of the\nabsorption peak with respect to the emission peak (Franck-Condon shift). The\nmagnitude of this shift in semiconductor quantum dots is still unknown. Here we\nreport first-principle calculations of excited-state relaxations in small\n(diameter < 2.2 nm) Si nanocrystals, showing that the Franck-Condon shift is\nsurprisingly large (~60 meV for a 2.2 nm-diameter nanocrystal). The physical\nmechanism of the excited-state relaxations changes abruptly around 1 nanoeter\nin size, providing a clear demarcation between ``molecules'' and\n``nanocrystals''."
    },
    {
        "anchor": "Multi-mode technique for the determination of the biaxial Y2SiO5\n  permittivity tensor from 300 to 6 Kelvin: The Y2SiO5 (YSO) crystal is a dielectric material with biaxial anisotropy\nwith known values of refractive index at optical frequencies. It is a\nwell-known rare-earth (RE) host material for optical research and more recently\nhas shown promising performance for quantum-engineered devices. In this paper,\nwe report the first microwave characterization of the real permittivity tensor\nof a bulk YSO sample, as well as an investigation of the temperature dependence\nof the tensor components from 296 K down to 6 K. Estimated uncertainties were\nbelow 0.26%, limited by the precision of machining the cylindrical dielectric.\nAlso, the electrical Q-factors of a few electromagnetic modes were recorded as\na way to provide some information about the crystal losses over the temperature\nrange. To solve the tensor components necessary for a biaxial crystal, we\ndeveloped the multi-mode technique, which uses simultaneous measurement of low\norder Whispering Gallery Modes. Knowledge of the permittivity tensor offers\nimportant data, essential for the design of technologies involving YSO, such as\nmicrowave coupling to electron and hyperfine transitions in RE doped samples at\nlow temperatures.",
        "positive": "Quasi one-dimensional transport in single GaAs/AlGaAs core-shell\n  nanowires: We present an original approach to fabricate single GaAs/AlGaAs core-shell\nnanowire with robust and reproducible transport properties. The core-shell\nstructure is buried in an insulating GaAs overlayer and connected as grown in a\ntwo probe set-up using the highly doped growth substrate and a top diffused\ncontact. The measured conductance shows a non-ohmic behavior with temperature\nand voltage-bias dependences following power laws, as expected for a quasi-1D\nsystem."
    },
    {
        "anchor": "Effect of crystallographic dislocations on the reverse performance of\n  4H-SiC p-n diodes: A quantitative study was performed to investigate the impact of\ncrystallographic dislocation defects, 21 including screw dislocation, basal\nplane dislocation, and threading edge dislocation, and their locations in 22\nactive and JTE region, on the reverse performance of 4H-SiC p-n diodes. It was\nfound that higher leakage 23 current in diodes is associated with basal plane\ndislocations, while lower breakdown voltage is attributed to 24 screw\ndislocations. The above influence increases in severity when the dislocation is\nin the active region than 25 in the JTE region. Furthermore, due to the\nclosed-core nature, the impact of threading edge dislocation on the 26 reverse\nperformance of the p-n diodes is less severe than that of other dislocations\nalthough its density is 27 much higher.",
        "positive": "Laser-induced real-space topology control of spin wave resonances: Femtosecond laser excitation of materials that exhibit magnetic spin textures\npromises advanced magnetic control via the generation of ultrafast and\nnon-equilibrium spin dynamics. We explore such possibilities in ferrimagnetic\n[Fe(0.35 nm)/Gd(0.40 nm)]$_{160}$ multilayers, which host a rich diversity of\nmagnetic textures from stripe domains at low magnetic fields, a dense\nbubble/skyrmion lattice at intermediate fields, and a single domain state for\nhigh magnetic fields. Using femtosecond magneto-optics, we observe distinct\ncoherent spin wave dynamics in response to a weak laser excitation allowing us\nto unambiguously identify the different magnetic spin textures. Moreover,\nemploying strong laser excitation we show that we achieve versatile control of\nthe coherent spin dynamics via non-equilibrium and ultrafast transformation of\nmagnetic spin textures by both creating and annihilating bubbles/skyrmions. We\ncorroborate our findings by micromagnetic simulations and by Lorentz\ntransmission electron microscopy before and after laser exposure."
    },
    {
        "anchor": "The challenge of unravelling magnetic properties in LaFeAsO: First principles calculations of magnetic and, to a lesser extent, electronic\nproperties of the novel LaFeAsO-based superconductors show substantial apparent\ncontroversy, as opposed to most weakly or strongly correlated materials. Not\nonly do different reports disagree about quantitative values, there is also a\nschism in terms of interpreting the basic physics of the magnetic interactions\nin this system. In this paper, we present a systematic analysis using four\ndifferent first principles methods and show that while there is an unusual\nsensitivity to computational details, well-converged full-potential\nall-electron results are fully consistent among themselves. What makes results\nso sensitive and the system so different from simple local magnetic moments\ninteracting via basic superexchange mechanisms is the itinerant character of\nthe calculated magnetic ground state, where very soft magnetic moments and\nlong-range interactions are characterized by a particular structure in the\nreciprocal (as opposed to real) space. Therefore, unravelling the magnetic\ninteractions in their full richness remains a challenging, but utterly\nimportant task.",
        "positive": "Origin of the large phonon band-gap in SrTiO3 and the vibrational\n  signatures of ferroelectricity in ATiO3 perovskite: First principles lattice\n  dynamics and inelastic neutron scattering of PbTiO3, BaTiO3 and SrTiO3: We report first principles density functional perturbation theory\ncalculations and inelastic neutron scattering measurements of the phonon\ndensity of states, dispersion relations and electromechanical response of\nPbTiO3, BaTiO3 and SrTiO3. The phonon density-of-states of the quantum\nparaelectric SrTiO3 is found to be fundamentally distinct from that of\nferroelectric PbTiO3 and BaTiO3 with a large 70-90 meV phonon band-gap. The\nphonon dispersion and electromechanical response of PbTiO3 reveal giant\nanisotropies. The interplay of covalent bonding and ferroelectricity, strongly\nmodulates the electromechanical response and give rise to spectacular\nsignatures in the phonon spectra. The computed charge densities have been used\nto study the bonding in these perovskites. Distinct bonding characteristics in\nthe ferroelectric and paraelectric phases give rise to spectacular vibrational\nsignatures. While a large phonon band-gap in ATiO3 perovskites seems a\ncharacteristic of quantum paraelectrics, anisotropy of the phonon spectra\ncorrelates well with ferroelectric strength. These correlations between the\nphonon spectra and ferroelectricity, can guide future efforts at custom\ndesigning still more effective piezoelectrics for applications. These results\nsuggest that vibrational spectroscopy can help design novel materials."
    },
    {
        "anchor": "Effect of the Fe substitution in Ti-Ni shape memory alloys: Shape memory Ti-Ni alloys attracted much attention in the recent years, since\nthey are shape memory, intelligent as well as functional materials. In the\npresent investigation Ti51Ni49 and Ti51Ni45Fe4 alloys were synthesized through\nradio frequency (RF) induction melting. The alloy was characterized through\nx-ray diffraction (XRD), scanning electron microscopy (SEM), Mossbauer\nspectroscopy (MS) and positron annihilation techniques (PAT).The Fe\nsubstitution stabilized the TiNi type cubic (a=2.998 A) phase. The surface\nmicrostructure and presence of the oxide layer in Ti51Ni45Fe4 alloy have been\ninvestigated by SEM. The Positron annihilation measurements indicated a similar\nbulk electron density in both the as-cast and annealed (1000 0 C for 30 hrs)\nalloys, typically like that of bulk Ti. Mossbauer spectroscopy studies of\nas-cast and annealed iron substituted samples showed regions in the samples\nwhere nuclear Zeeman splitting of Fe levels occurred and an oxide phase was\nfound to be present in as cast Ti51Ni45Fe4 alloy, while annealed sample\nindicated the presence of bcc iron phase .",
        "positive": "Surface properties of the clean and Au/Pd covered Fe$_3$O$_4$(111): a\n  DFT and DFT+$U$ study: The spin-density functional theory (DFT) and DFT+$U$ with Hubbard $U$ term\naccounting for on-site Coulomb interactions were applied to investigate\nstructure, stability, and electronic properties of different terminations of\nthe Fe$_3$O$_4$(111) surface. All terminations of the ferrimagnetic\nFe$_3$O$_4$(111) surface exhibit very large (up to 90%) relaxations of the\nfirst four interlayer distances, decreasing with the oxide layer depth. Our\ncalculations predict the iron terminated surface to be most stable in a wide\nrange of the accessible values of the oxygen chemical potential. The adsorption\nof Au and Pd on two stable Fe- and O-terminated surfaces is studied. Our\nresults show that Pd binds stronger than Au both to the Fe- and O-terminated\nsurface. DFT+$U$ gives stronger bonding than DFT. The bonding of both\nadsorbates to the O-terminated magnetite surface is by 1.5-2.5 eV stronger than\nto the Fe-terminated surface."
    },
    {
        "anchor": "Graph Atomic Cluster Expansion for semilocal interactions beyond\n  equivariant message passing: The Atomic Cluster Expansion provides local, complete basis functions that\nenable efficient parametrization of many-atom interactions. We extend the\nAtomic Cluster Expansion to incorporate graph basis functions. This naturally\nleads to representations that enable the efficient description of semilocal\ninteractions in physically and chemically transparent form. Simplification of\nthe graph expansion by tensor decomposition results in an iterative procedure\nthat comprises current message-passing machine learning interatomic potentials.\nWe demonstrate the accuracy and efficiency of the graph Atomic Cluster\nExpansion for a number of small molecules, clusters and a general-purpose model\nfor carbon. We further show that the graph Atomic Cluster Expansion scales\nlinearly with number of neighbors and layer depth of the graph basis functions.",
        "positive": "Structural and Magnetic Characterization of Ni2MnBO5 ludwigite: Single crystals of ludwigite Ni2MnBO5 were synthesized by flux growth\ntechnique. The detailed structural and magnetic characterizations of the\nsynthesized samples have been carried out. The cations composition of the\nstudied crystal was determined using X-ray diffraction and EXAFS technique, the\nresulting composition is differ from the content of the initial Mn2O3 - CuO\ncomponents of flux. Magnetic susceptibility measurements and the calculations\nof the exchange integrals in frameworks of indirect coupling model revealed\nstrong antiferromagnetic interactions and appearance of magnetic ordering phase\nat the temperature T=85 K. The hypothesis of the existence of several magnetic\nsubsystems was supposed."
    },
    {
        "anchor": "Tailoring the SiC surface - a morphology study on the epitaxial growth\n  of graphene and its buffer layer: We investigate the growth of the graphene buffer layer and the involved step\nbunching behavior of the silicon carbide substrate surface using atomic force\nmicroscopy. The formation of local buffer layer domains are identified to be\nthe origin of undesirably high step edges in excellent agreement with the\npredictions of a general model of step dynamics. The applied polymer-assisted\nsublimation growth method demonstrates that the key principle to suppress this\nbehavior is the uniform nucleation of the buffer layer. In this way, the\nsilicon carbide surface is stabilized such that ultra-flat surfaces can be\nconserved during graphene growth on a large variety of silicon carbide\nsubstrate surfaces. The analysis of the experimental results describes\ndifferent growth modes which extend the current understanding of epitaxial\ngraphene growth by emphasizing the importance of buffer layer nucleation and\ncritical mass transport processes.",
        "positive": "Spin-wave thermal population as temperature probe in Magnetic Tunnel\n  Junctions: We study whether a direct measurement of the absolute temperature of a\nMagnetic Tunnel Junction (MTJ) can be performed using the high frequency\nelectrical noise that it delivers under a finite voltage bias. Our method\nincludes quasi-static hysteresis loop measurements of the MTJ, together with\nthe field-dependence of its spin wave noise spectra. We rely on an analytical\nmodeling of the spectra by assuming independent fluctuations of the different\nsub-systems of the tunnel junction that are described as macrospin fluctuators.\nWe illustrate our method on perpendicularly magnetized MgO-based MTJs patterned\nin 50*100 nm2 nanopillars. We apply hard axis (in-plane) fields to let the\nmagnetic thermal fluctuations yield finite conductance fluctuations of the MTJ.\nInstead of the free layer fluctuations that are observed to be affected by both\nspin-torque and temperature, we use the magnetization fluctuations of the sole\nreference layers. Their much stronger anisotropy and their much heavier damping\nrender them essentially immune to spin-torque. We illustrate our method by\ndetermining current-induced heating of the perpendicularly magnetized tunnel\njunction at voltages similar to those used in spin-torque memory applications.\nThe absolute temperature can be deduced with a precision of +/- 60 K and we can\nexclude any substantial heating at the spin-torque switching voltage."
    },
    {
        "anchor": "On a non-linear sigma model of knotted relaxed states far from\n  thermodynamic equilibrium in plasma physics and beyond: We show that a Faddeev-Niemi non-linear sigma model describes in the long\nwavelength limit a wide class of steady-state, knotted physical systems far\nfrom thermodynamic equilibrium which are stable against perturbations of\ntemperature and interact weakly with the external world. In these systems\ntemperature gradients are negligible, inertial effects are negligible in\ncomparison with diffusion effects, entropy is mainly produced through Joule\nand-or viscous heating, the macroscopic state is described by specifying a unit\nvector at each point, and the Gauss linking number of this unit vector is lower\nthan a threshold. In fluids and plasmas, the model describes filamentary\nstructures which adjust themselves in order to offer minimum resistance to the\nmedium embedding them and to the electric currents (if any) flowing across\nthem; in the latter case, Gauss linking number is related to magnetic helicity.\nBoth n and the relative velocity of the filament with respect to the medium are\napproximately Double Beltrami vector fields. We derive a stability criterion\nfor a double helix. Moreover, a similar discussion describes the recently\ndiscovered writing process of skyrmions in a magnetic film with the help of a\nbeam of polarised electrons. We derive a lower bound on the value of beam\ncurrent required to write a skyrmion.",
        "positive": "Electronic structure and orbital polarization of LaNiO$_3$ with a\n  reduced coordination and under strain: first-principles study: First-principles density functional theory calculations have been performed\nto understand the electronic structure and orbital polarization of LaNiO$_3$\nwith a reduced coordination and under strain. From the slab calculation to\nsimulate [001] surface, it is found that $d_{3z^2-r^2}$ orbital occupation is\nsignificantly enhanced relative to $d_{x^2-y^2}$ occupation owing to the\nreduced coordination along the perpendicular direction to the sample plane.\nFurthermore, the sign of the orbital polarization does not change under\nexternal strain. The results are discussed in comparison to the bulk and\nheterostructure cases, which sheds new light on the understanding of the\navailable experimental data."
    },
    {
        "anchor": "Isotope effect on electron paramagnetic resonance of boron acceptors in\n  silicon: The fourfold degeneracy of the boron acceptor ground state in silicon, which\nis easily lifted by any symmetry breaking perturbation, allows for a strong\ninhomogeneous broadening of the boron-related electron paramagnetic resonance\n(EPR) lines, e.g. by a random distribution of local strains. However, since EPR\nof boron acceptors in externally unstrained silicon was reported for the first\ntime, neither the line shape nor the magnitude of the residual broadening\nobserved in samples with high crystalline purity were compatible with the low\nconcentrations of carbon and oxygen point defects, being the predominant source\nof random local strain. Adapting a theoretical model which has been applied to\nunderstand the acceptor ground state splitting in the absence of a magnetic\nfield as an effect due to the presence of different silicon isotopes, we show\nthat local fluctuations of the valence band edge due to different isotopic\nconfigurations in the vicinity of the boron acceptors can quantitatively\naccount for all inhomogeneous broadening effects in high purity Si with a\nnatural isotope composition. Our calculations show that such an isotopic\nperturbation also leads to a shift in the g-value of different boron-related\nresonances, which we could verify in our experiments. Further, our results\nprovide an independent test and verification of the valence band offsets\nbetween the different Si isotopes determined in previous works.",
        "positive": "Effect of annealing temperature on morphology, structure and\n  photocatalytic behavior of nanotubed H2Ti2O4(OH)2: Nanotubed titanic acid (H2Ti2O4(OH)2) was prepared from nanotubed sodium\ntitanate (Na2Ti2O4(OH)2) by an ion exchange reaction in a pH=1 HCl solution.\nThe effect of annealing temperature on the morphology, structure and\nphotocatalytic behavior of nanotubed H2Ti2O4(OH)2 was studied by means of TEM,\nXRD, DTG, DSC, BET and ESR. The results showed that nanotubed H2Ti2O4(OH)2 is\nthermally unstable. Its dehydration consists of two steps. In the first-step\ndehydration, single-electron-trapped oxygen vacancies (SETOVs) were generated.\nAccompanying the second-step dehydration, the transition of crystal form from\northorhombic system to anatase took place, at the same time the nanotubes\nbroke. At T>300 {\\deg}C, when the SETOV concentration greatly increased, the\ninteraction between SETOV happened. (VOo)x formed could play the role of\nrecombination center of photogenerated e--h+ and make the photocatalytic\nbehavior of TiO2 (anatase, obtained from 500 {\\deg}C-treated nanotubed\nH2Ti2O4(OH)2) to become bad."
    },
    {
        "anchor": "Ultralow thermal conductivity of single crystalline porous silicon\n  nanowires: Porous materials provide a large surface to volume ratio, thereby providing a\nknob to alter fundamental properties in unprecedented ways. In thermal\ntransport, porous nanomaterials can reduce thermal conductivity by not only\nenhancing phonon scattering from the boundaries of the pores and therefore\ndecreasing the phonon mean free path, but also by reducing the phonon group\nvelocity. Here we establish a structure-property relationship by measuring the\nporosity and thermal conductivity of individual electrolessly etched single\ncrystalline silicon nanowires using a novel electron beam heating technique.\nSuch porous silicon nanowires exhibit extremely low diffusive thermal\nconductivity (as low as 0.33 Wm-1K-1 at 300K for 43% porosity), even lower than\nthat of amorphous silicon. The origin of such ultralow thermal conductivity is\nunderstood as a reduction in the phonon group velocity, experimentally verified\nby measuring the Young modulus, as well as the smallest structural size ever\nreported in crystalline Silicon (less than 5nm). Molecular dynamics simulations\nsupport the observation of a drastic reduction in thermal conductivity of\nsilicon nanowires as a function of porosity. Such porous materials provide an\nintriguing platform to tune phonon transport, which can be useful in the design\nof functional materials towards electronics and nano-electromechanical systems.",
        "positive": "Hyper-domains in exchange bias micro-stripe pattern: A combination of experimental techniques, e.g. vector-MOKE magnetometry, Kerr\nmicroscopy and polarized neutron reflectometry, was applied to study the field\ninduced evolution of the magnetization distribution over a periodic pattern of\nalternating exchange bias stripes. The lateral structure is imprinted into a\ncontinuous ferromagnetic/antiferromagnetic exchange-bias bi-layer via laterally\nselective exposure to He-ion irradiation in an applied field. This creates an\nalternating frozen-in interfacial exchange bias field competing with the\nexternal field in the course of the re-magnetization. It was found that in a\nmagnetic field applied at an angle with respect to the exchange bias axis\nparallel to the stripes the re-magnetization process proceeds via a variety of\ndifferent stages. They include coherent rotation of magnetization towards the\nexchange bias axis, precipitation of small random (ripple) domains, formation\nof a stripe-like alternation of the magnetization, and development of a state\nin which the magnetization forms large hyper-domains comprising a number of\nstripes. Each of those magnetic states is quantitatively characterized via the\ncomprehensive analysis of data on specular and off-specular polarized neutron\nreflectivity. The results are discussed within a phenomenological model\ncontaining a few parameters which can readily be controlled by designing\nsystems with a desired configuration of magnetic moments of micro- and\nnano-elements."
    },
    {
        "anchor": "Inferring orientation distributions in anisotropic powders of\n  nano-layered crystallites from a single two-dimensional WAXS image: The wide-angle scattering of X-rays by anisotropic powders of nano-layered\ncrystallites (nano-stacks) is addressed. Assuming that the orientation\ndistribution probability function f of the nano-stacks only depends on the\ndeviation of the crystallites' orientation from a fixed reference direction, we\nderive a relation providing f from the dependence of a given diffraction peak's\namplitude on the azimuthal angle. The method is applied to two systems of\nNa-fluorohectorite (NaFH) clay particles, using synchrotron radiation and a\nWAXS setup with a two-dimensional detector. In the first system, which consists\nof dry-pressed NaFH samples, the orientation distribution probability function\ncorresponds to a classical uniaxial nematic order. The second system is\nobserved in bundles of polarized NaFH particles in silicon oil; in this case,\nthe nanostacks have their directors on average in a plane normal to the\nreference direction, and f is a function of the angle between a nano-stack's\ndirector and that plane. In both cases, a suitable Maier-Saupe function is\nobtained for the distributions, and the reference direction is determined with\nrespect to the laboratory frame. The method only requires one scattering image.\nBesides, consistency can be checked by determining the orientation distribution\nfrom several diffraction peaks independently.",
        "positive": "Spectral properties of interacting magnetoelectric particles: The linear magnetoelectric (ME) effect provides a special route for linking\nmagnetic and electric properties. In microwaves, a local ME effect appears due\nto the dynamical symmetry breakings of magnetic-dipolar modes (MDMs) in a\nferrite disk particle. The fact that for MDMs in a ferrite disk one has evident\nboth classical and quantum-like attributes, puts special demands on the methods\nused for study of interacting ME particles. A proper model for coupled\nparticles should be based on the spectral characteristics of MDM oscillations\nand an analysis of the overlap integrals for interacting eigen oscillating ME\nelements. In this paper, we present theoretical studies of spectral properties\nof literally coupled of MDM ME disks. We show that there exists the \"exchange\"\nmechanism of interaction between the particles, which is distinctive from the\nmagnetostatic interaction between magnetic dipoles. The spectral method\nproposed in this paper may further the development of a theory of ME\n\"molecules\" and realization of local ME composites."
    },
    {
        "anchor": "Thermal recovery of colour centres induced in cubic yttria-stabilized\n  zirconia by charged particle irradiations: We have used electron paramagnetic resonance to study the thermal annealing\nof colour centres induced in cubic yttria-stabilized zirconia by swift electron\nand heavy ion-irradiations. Single crystals were irradiated with 1 or 2-MeV\nelectrons, and 200-MeV 127I, or 200-MeV 197Au ions. Electron and ion beams\nproduce the same colour centres: namely i) an F+-like centre, ii) the so-called\nT-centre (Zr3+ in a trigonal oxygen local environment), and iii) a hole center.\nIsochronal annealing was performed up to 973 K. Isothermal annealing was\nperformed at various temperatures on samples irradiated with 2-MeV electrons.\nThe stability of paramagnetic centres increases with fluence and with a TCR\ntreatment at 1373 K under vacuum prior to the irradiations. Two distinct\nrecovery processes are observed depending on fluence and/or thermal treatment.\nThe single-stage type I process occurs for F+-like centres at low fluences in\nas-received samples, and is probably linked to electron-hole recombination.\nT-centres are also annealed according to a single-stage process regardless of\nfluence. The annealing curves allow one to obtain activation energies for\nrecovery. The two-stage type II process is observed only for the F+-like\ncentres in as-received samples, at higher fluences, or in reduced samples.\nThese centres are first annealed in a first stage below 550 K, like in type I,\nthen transform into new paramagnetic centres in a second stage above 550 K. A\nsimple kinetics model is proposed for this process. Complete colour centre\nbleaching is achieved at about 1000 K.",
        "positive": "Thermal quenching of electronic shells and channel competition in\n  cluster fission: Experimental and theoretical studies of fission of doubly-charged Li, Na, and\nK clusters in the low fissility regime reveal the strong influence of\nelectronic shell effects on the fission products. The electronic entropy\ncontrols the quenching of the shell effects and the competition between\nmagic-fragment channels, leading to a transition from favored channels of\nhigher mass symmetry to the asymmetric channel involving the trimer cation at\nelevated temperatures."
    },
    {
        "anchor": "Structure and stability of carbon nitrides: ring opening induced\n  photoelectrochemical degradation: A constant increase in the need of clean energy demands more innovation from\nthe research community. Active and stable materials that can make use of the\nsolar radiation to promote different reactions are the cornerstone of emerging\ntechnologies. Polymeric carbon nitrides that harvest solar radiation to drive\nelectrochemical reactions are considered solid candidates. In this respect,\npolymeric carbon nitrides were prepared by the thermal polycondensation of\nmelamine. As-obtained materials were characterized by synchrotron radiation and\nlab-based techniques. The electron band structure was fully characterized by a\ncombined electrochemical optoelectronic study. Electron microscopy studies\nbefore and after the photoelectrochemical experiments showed morphological and\nstructure degradation. The work at-hand concludes that polymeric carbon\nnitrides are prone to photoelectrochemical degradation at high overpotentials.",
        "positive": "Low-angle misorientation dependence of the optical properties of\n  InGaAs/InAlAs quantum wells: We investigate the dependence of the low-temperature photoluminescence\nlinewidths from InP-lattice-matched InGaAs/InAlAs quantum wells on the\nlow-angle misorientation from the (100) surface of the host InP substrate.\nQuantum wells were grown on InP substrates misorientated by 0, 0.2, 0.4 and 0.6\ndegrees; 0.4 degrees was found to consistently result in the narrowest peaks,\nwith the optimal spectral purity of ~4.25 meV found from a 15nm quantum well.\nThe width of the emission from the 15nm quantum well was used to optimize the\ngrowth parameters. Thick layers of Si-doped InGaAs were then grown and found to\nhave bulk, low temperature (77 K), electron mobilities up to \\mu ~ 3.5 x 10^4\ncm2/Vs with an electron concentration of ~1 x 10^16."
    },
    {
        "anchor": "A materials perspective on the design of damage-resilient artificial\n  bones and bone implants through additive/advanced manufacturing: After more than five decades of research, the failure of bone implants is\nstill an issue that becomes increasingly urgent to solve in our ageing\npopulation. Among the reasons for failure, catastrophic brittle fracture is one\nevent that is directly related to the implant s material and fabrication and\nthat deserves more attention. Indeed, clinically available implants pale at\nreproducing the hierarchical and heterogeneous microstructural organization of\nour natural bones, ultimately failing at reproducing their mechanical strength\nand toughness. Nevertheless, the recent advances in additive and advanced\nmanufacturing open new horizons for the fabrication of biomimetic bone\nimplants, challenging at the same time their characterization, testing and\nmodelling. This critical review covers selected recent achievements in bone\nimplant research from a materials standpoint and aims at deciphering some of\nthe most urgent issues in this multidisciplinary field.",
        "positive": "Silicon and III-V compound nanotubes: structural and electronic\n  properties: Unusual physical properties of single-wall carbon nanotubes have started a\nsearch for similar tubular structures of other elements. In this paper, we\npresent a theoretical analysis of single-wall nanotubes of silicon and group\nIII-V compounds. Starting from precursor graphene-like structures we\ninvestigated the stability, energetics and electronic structure of zigzag and\narmchair tubes using first-principles pseudopotential plane wave method and\nfinite temperature ab-initio molecular dynamics calculations. We showed that\n(n,0) zigzag and (n,n) armchair nanotubes of silicon having n > 6 are stable\nbut those with n < 6 can be stabilized by internal or external adsorption of\ntransition metal elements. Some of these tubes have magnetic ground state\nleading to spintronic properties. We also examined the stability of nanotubes\nunder radial and axial deformation. Owing to the weakness of radial restoring\nforce, stable Si nanotubes are radially soft. Undeformed zigzag nanotubes are\nfound to be metallic for 6 < n < 11 due to curvature effect; but a gap starts\nto open for n > 12. Furthermore, we identified stable tubular structures formed\nby stacking of Si polygons. We found AlP, GaAs, and GaN (8,0) single-wall\nnanotubes stable and semiconducting. Our results are compared with those of\nsingle-wall carbon nanotubes."
    },
    {
        "anchor": "Enhanced spin-orbit torques in MnAl/Ta films with improving chemical\n  ordering: We report the enhancement of spin-orbit torques in MnAl/Ta films with\nimproving chemical ordering through annealing. The switching current density is\nincreased due to enhanced saturation magnetization MS and effective anisotropy\nfield HK after annealing. Both damplinglike effective field HD and fieldlike\neffective field HF have been increased in the temperature range of 50 to 300 K.\nHD varies inversely with MS in both of the films, while the HF becomes liner\ndependent on 1/MS in the annealed film. We infer that the improved chemical\nordering has enhanced the interfacial spin transparency and the transmitting of\nthe spin current in MnAl layer.",
        "positive": "Deep Learning Analysis of Defect and Phase Evolution During Electron\n  Beam Induced Transformations in WS2: Understanding elementary mechanisms behind solid-state phase transformations\nand reactions is the key to optimizing desired functional properties of many\ntechnologically relevant materials. Recent advances in scanning transmission\nelectron microscopy (STEM) allow the real-time visualization of solid-state\ntransformations in materials, including those induced by an electron beam and\ntemperature, with atomic resolution. However, despite the ever-expanding\ncapabilities for high-resolution data acquisition, the inferred information\nabout kinetics and thermodynamics of the process and single defect dynamics and\ninteractions is minima, due to the inherent limitations of manual ex-situ\nanalysis of the collected volumes of data. To circumvent this problem, we\ndeveloped a deep learning framework for dynamic STEM imaging that is trained to\nfind the structures (defects) that break a crystal lattice periodicity and\napply it for mapping solid state reactions and transformations in layered WS2\ndoped with Mo. This framework allows extracting thousands of lattice defects\nfrom raw STEM data (single images and movies) in a matter of seconds, which are\nthen classified into different categories using unsupervised clustering\nmethods. We further expanded our framework to extract parameters of diffusion\nfor the sulfur vacancies and analyzed transition probabilities associated with\nswitching between different configurations of defect complexes consisting of Mo\ndopant and sulfur vacancy, providing insight into point defect dynamics and\nreactions. This approach is universal and its application to beam induced\nreactions allows mapping chemical transformation pathways in solids at the\natomic level."
    },
    {
        "anchor": "Encapsulation, compensation, and substitution of catalyst particles\n  during continuous growth of carbon nanotubes: By sequential feeding of catalyst materials, it is revealed that the active\ngrowth sites are at the bottom of the carbon nanotubes (CNTs), and that\ncatalyst particles are constantly encapsulated into nanotubes from the bottom.\nThis gives a better insight into the mechanism of CNT formation and on ways to\ncontrol the growth process. CNTs encapsulated with different materials should\nenable the study of their electronic or magnetic properties, with potential\napplications as building blocks for nanoelectronics and as fillers in\ncomposites for electromagenetic shielding.",
        "positive": "Facile patterning of functional materials via gas-phase 3D printing: Spatial Atomic Layer Deposition (SALD) is a recent approach that is up to two\norders of magnitude faster than conventional ALD, and that can be performed at\natmospheric pressure and even in the open air. Previous works have exploited\nthese assets to focus on the possibility of high-rate, large-area deposition\nfor scaling up into mass production. Conversely, here we show that SALD indeed\nrepresents an ideal platform for the selective deposition of functional\nmaterials by proper design and miniaturization of SALD close-proximity heads.\nIn particular, we have used the potential offered by 3D printing to fabricate\ncustom close-proximity SALD injection heads. By using 3D printing, the heads\ncan be easily designed and readily modified to obtain different deposition\nareas, free-form patterns, and even complex multimaterial structures. The heads\ncan be printed in different materials to adjust to the chemistry of the\nprecursors and the deposition conditions used. Polymeric heads can be used as\ncheap (even disposable) heads that are both used for performing deposition and\nfor prototyping and optimization purposes. Finally, by designing a miniaturized\nhead with circular concentric gas channels, 3D printing of functional materials\ncan be performed with nanometric resolution in Z. This constitutes a new 3D\nprinting approach based on gaseous precursors. Because the selective deposition\nstrategies presented here are based on the SALD process, conformal and\ncontinuous thin films of functional materials can be printed at low\ntemperatures and with high deposition rate in the open air. Our approach\nrepresents a new versatile way of printing functional materials and devices\nwith spatial and topological control, thus extending the potential of SALD and\nALD in general, and opening a new avenue in the field of area-selective\ndeposition of functional materials."
    },
    {
        "anchor": "A 17 T horizontal field cryomagnet with rapid sample change designed for\n  beamline use: We describe a new 17 T cryomagnet for neutron, x-ray or optical experiments\nwith rapid in-situ sample change. Sample temperatures are controllable from < 2\nK to 300 K in vacuum. Alternatively a room temperature bore insert can be used\nfor experiments in the field centre under atmospheric conditions. Some\nadvantages of this system include very low background scattering due to the\nsmall amount of material in the beam path, rapid cooldown, and fast field\nramping. Access is available in a ~10-11 degree cone around the field direction\non both sides.",
        "positive": "New Superhard Carbon Phases Between Graphite and Diamond: Two new carbon allotropes (H-carbon and S-carbon) are proposed, as possible\ncandidates for the intermediate superhard phases between graphite and diamond\nobtained in the process of cold compressing graphite, based on the results of\nfirst-principles calculations. Both H-carbon and S-carbon are more stable than\npreviously proposed M-carbon and W-carbon and their bulk modulus are comparable\nto that of diamond. H-carbon is an indirect-band-gap semiconductor with a gap\nof 4.459 eV and S-carbon is a direct-band-gap semiconductor with a gap of 4.343\neV. The transition pressure from cold compressing graphite is 10.08 GPa and\n5.93 Gpa for H-carbon and S-carbon, respectively, which is in consistent with\nthe recent experimental report."
    },
    {
        "anchor": "ZnO Defect Modulation for Efficient Photocatalysis: We have investigated the combined effect of low-energy self-implantation and\nthermal annealing on the near-surface defect concentration of ZnO\nsingle-crystals. Using ionoluminescence (IL), we demonstrate that a combination\nof low-energy low-fluence Zn and O ion implantation followed by annealing in Ar\nincreases the near-surface point defect concentration in ZnO by two orders of\nmagnitude. Point defects are known to increase the surface reactivity of ZnO,\nthereby improving the efficiency of ZnO photocatalytic processes such as\nbilirubin degredation. We hereby provide recommendations on how to improve the\nefficiency of ZnO-related photocatalytic processes.",
        "positive": "Maximizing the spin-orbit torque efficiency of Pt/Ti multilayers by\n  optimization of the tradeoff between the intrinsic spin Hall conductivity and\n  carrier lifetime: We report a comprehensive study of the maximization of the spin Hall ratio\n({\\theta}SH) in Pt thin films by the insertion of sub-monolayer layers of Ti to\ndecrease carrier lifetime while minimizing the concurrent reduction in the spin\nHall conductivity. We establish that the intrinsic spin Hall conductivity of\nPt, while robust against the strain and the moderate interruption of crystal\norder caused by these insertions, begins to decrease rapidly at high\nresistivity level because of the shortening carrier lifetime. The unavoidable\ntrade-off between the intrinsic spin Hall conductivity and carrier lifetime\nsets a practical upper bound of {\\theta}SH >=0.8 for heterogeneous materials\nwhere the crystalline Pt component is the source of the spin Hall effect and\nthe resistivity is increased by shortening carrier lifetime. This work also\nestablishes a very promising spin-Hall metal of [Pt 0.75 nm/Ti 0.2 nm]7/Pt 0.75\nnm for energy-efficient, high-endurance spin-orbit torque technologies (e.g.,\nmemories, oscillators, and logic) due to its combination of a giant {\\theta}SH\nof 0.8, or equivalently a dampinglike spin torque efficiency per unit current\ndensity of 0.35, with a relatively low resistivity (90 uOhm cm) and high\nsuitability for practical technology integration."
    },
    {
        "anchor": "Microstructure-dependent magnetic properties of iron silicon single, bi-\n  and oligo-crystals measured with a miniaturised Single-Sheet-Tester: Electrical iron silicon steel is the most commonly used soft magnetic\nmaterial in electrical energy conversion and transmission, and its demand is\nexpected to increase with the need for electrification of the transportation\nsector and the transition to renewable energy to combat climate change.\nAlthough iron silicon steel has been used for more than 100 years, some\nfundamental relationships between microstructure and magnetic performance\nremain vague, especially with regard to the role of crystal defects such as\ngrain boundaries and dislocations that are induced during the final cutting\nstep of the process chain. In this paper we present first results of a new\napproach to quantify the effects of orientation, grain boundaries and\ndeformation on the magnetic properties of single, bi- and oligo-crystals using\na miniaturised Single-Sheet-Tester. In this way, we were able to better resolve\nthe orientation-dependent polarisation curves at low field strengths, revealing\nan additional intersection between the medium and hard axis. Furthermore, we\nwere able to distinguish the effects of different deformation structures - from\nsingle dislocations to tangles to localised deformation and twins - on\ndifferent magnetic properties such as on coercivity, remanence and\nsusceptibility, and we found that our particular grain boundary strongly\nreduces the remanence.",
        "positive": "High Field (up to 140kOe) Angle Dependent Magneto Transport of Bi2Te3\n  Single Crystals: We report the angle dependent high field (up to 140kOe) magneto transport of\nBi2Te3 single crystals, a well-known topological insulator. The crystals were\ngrown from melt of constituent elements via solid state reaction route by\nself-flux method. Details of crystal growth along with their brief\ncharacterization up to 5 Tesla applied field was reported by some of us\nrecently [J. Magn. Mag. Mater. 428, 213 (2017)]. The angle dependence of the\nmagneto-resistance (MR) of Bi2Te3 follows the cos Theta function i.e., MR is\nresponsive, when the applied field is perpendicular (tilt angle Theta = o\nand/or 180) to the transport current. The low field (10 kOe) MR showed the\nsignatures of weak anti localization (WAL) character with typical cusp near\norigin at 5 K. Further, the MR is linear right up to highest applied field of\n140 kOe. The large positive MR are observed up to high temperatures and are\nabove 250 and 150 percent at 140 kOe in perpendicular fields at 50 K and 100 K\nrespectively. Heat capacity CP(T) measurements revealed the value of Debye\ntemperature to be 135 K. ARPES (angle resolved photoemission spectroscopy) data\nclearly showed that the bulk Bi2Te3 single crystal consists of a single Dirac\ncone."
    },
    {
        "anchor": "Origin Of the enhanced flexoelectricity of relaxor ferroelectrics: We have measured the bending-induced polarization of Pb(Mg1/3Nb2/3)O3-PbTiO3\nsingle crystals with compositions at the relaxor-ferroelectric phase boundary.\nThe crystals display very large flexoelectricity, with flexocoupling\ncoefficients an order of magnitude bigger than the theoretical upper limit set\nby the theories of Kogan and Tagantsev. This enhancement persists in the\nparaphrase up to a temperature T* that coincides with the start of elastic\nsoftening in the crystals. Analysis of the temperature dependence and\ncross-correlation between flexoelectric, dielectric and elastic properties\nindicates that the large bendinginduced polarization of relaxor ferroelectrics\nis not caused by intrinsically giant flexoelectricity, but by the reorientation\nof polar nanotwins that become ferroelastically active below T*.",
        "positive": "Resolution-dependent mechanisms for bimodal switching-time distributions\n  in simulated Fe nanopillars: We study the magnetization-switching statistics following reversal of the\napplied field for three separate computational models representing the same\nphysical system, an iron nanopillar. The primary difference between the models\nis the resolution of the computational lattice and, consequently, the intrinsic\nparameters that must be rescaled to retain similarity to the physical system.\nConsidering the first-passage time to zero for the magnetization component in\nthe longitudinal (easy-axis) direction, we look for applied fields that result\nin bimodal distributions of this time for each system and compare the results\nto the experimental system. We observe that the relevant fluctuations leading\nto bimodal distributions are different for each lattice resolution and result\nin magnetization-switching behavior that is unique to each computational model.\nCorrect model resolution is thus essential for obtaining reliable numerical\nresults for the system dynamics."
    },
    {
        "anchor": "Comparison of PM-HIP to Forged SA508 Pressure Vessel Steel Under\n  High-Dose Neutron Irradiation: Powder metallurgy with hot isostatic pressing (PM-HIP) is an advanced\nmanufacturing process that is envisioned to replace forging for heavy nuclear\ncomponents, including the reactor pressure vessel (RPV). But PM-HIP products\nmust at least demonstrate comparable irradiation tolerance than forgings in\norder to be qualified for nuclear applications. The objective of this study is\nto directly compare PM-HIP to forged SA508 Grade 3 Class 1 low-alloy RPV steel\nat two neutron irradiation conditions: ~0.5-1.0 displacements per atom (dpa) at\n~270C and ~370C. PM-HIP SA508 experiences greater irradiation hardening and\nembrittlement (total elongation) than forged SA508. However, uniform elongation\nand approximate toughness are comparable across all irradiated materials,\nsuggesting irradiated PM-HIP SA508 exhibits superior ductility at maximum\nload-bearing capacity. The irradiation hardening mechanism is linked to\ncomposition rather than fabrication method. Since PM-HIP SA508 has higher Mn\nand Ni concentration, it is more susceptible to irradiation-induced nucleation\nof Mn-Ni-Si-P (MNSP) nanoprecipitates and dislocation loops, which both\ncontribute to hardening. Conversely, the forged material nucleates fewer MNSPs,\ncausing dislocation loops to control irradiation hardening. These results show\npromise for the irradiation performance of PM-HIP SA508 and can motivate future\nnuclear code qualification of PM-HIP fabrication for RPVs.",
        "positive": "Fermi Statistics of Weakly Excited Granular Materials in a Vibrating Bed\n  II: One Dimensional Experiment: A one dimensional experiment in granular dynamics is carried out to test the\nthermodynamic theory of weakly excited granular systems [Hayakawa and Hong,\nPhys. Rev. Lett. {\\bf 78}, 2764(1997)] where granular particles are treated as\nspinless Fermions. The density profile is measured and then fit to the Fermi\ndistribution function, from which the global temperature of the system, T, is\ndetermined. Then the center of mass, <z(T)>, and its fluctuations, <(\\Delta\nz(T))^2>, are measured and plotted as functions of T. The Fermi function fits\nthe density profile fairly well, with the value of T being fairly close to the\npredicted value. The scaling behavior of <z(T)> and <(\\Delta z(T))^2> is in\nexcellent agreement with the theory."
    },
    {
        "anchor": "Unraveling the role of the magnetic anisotropy on thermoelectric\n  response: a theoretical and experimental approach: Magnetic anisotropies have key role to taylor magnetic behavior in\nferromagnetic systems. Further, they are also essential elements to manipulate\nthe thermoelectric response in Anomalous Nernst (ANE) and Longitudinal Spin\nSeebeck systems (LSSE). We propose here a theoretical approach and explore the\nrole of magnetic anisotropies on the magnetization and thermoelectric response\nof noninteracting multidomain ferromagnetic systems. The magnetic behavior and\nthe thermoelectric curves are calculated from a modified Stoner Wohlfarth model\nfor an isotropic system, a uniaxial magnetic one, as well as for a system\nhaving a mixture of uniaxial and cubic magnetocrystalline magnetic\nanisotropies. It is verified remarkable modifications of the magnetic behavior\nwith the anisotropy and it is shown that the thermoelectric response is\nstrongly affected by these changes. Further, the fingerprints of the energy\ncontributions to the thermoelectric response are disclosed. To test the\nrobustness of our theoretical approach, we engineer films having the specific\nmagnetic properties and compare directly experimental data with theoretical\nresults. Thus, experimental evidence is provided to confirm the validity of our\ntheoretical approach. The results go beyond the traditional reports focusing on\nmagnetically saturated films and show how the thermoelectric effect behaves\nduring the whole magnetization curve. Our findings reveal a promising way to\nexplore the ANE and LSSE effects as a powerful tool to study magnetic\nanisotropies, as well as to employ systems with magnetic anisotropy as sensing\nor elements in technological applications.",
        "positive": "Why the aspect ratio? Shape equivalence for the extinction spectra of\n  gold nanoparticles: We compare the light extinction spectra of elongated gold nanoparticles with\ndifferent shapes (cylinder, spherocylinder and ellipsoid) and sizes of 10 to\n100~nm. We argue that the equivalence of the various moments of mass\ndistribution is the natural comparison criterion -rather than the\nlength-to-diameter (aspect) ratio generally used in the literature- and that it\nleads to better spectral correspondence between the various shapes."
    },
    {
        "anchor": "Transport properties of single atoms: We present a systematic study of the ballistic electron conductance through\nsp and 3d transition metal atoms attached to copper and palladium crystalline\nelectrodes. We employ the 'ab initio' screened Korringa-Kohn-Rostoker Green's\nfunction method to calculate the electronic structure of nanocontacts while the\nballistic transmission and conductance eigenchannels were obtained by means of\nthe Kubo approach as formulated by Baranger and Stone. We demonstrate that the\nconductance of the systems is mainly determined by the electronic properties of\nthe atom bridging the macroscopic leads. We classify the conducting\neigenchannels according to the atomic orbitals of the contact atom and the\nirreducible representations of the symmetry point group of the system that\nleads to the microscopic understanding of the conductance. We show that if\nimpurity resonances in the density of states of the contact atom appear at the\nFermi energy, additional channels of appropriate symmetry could open. On the\nother hand the transmission of the existing channels could be blocked by\nimpurity scattering.",
        "positive": "Synthesis and scintillation properties of some dense X-ray phosphors: Many ultra-dense lutetium or gadolinium based compounds doped with Eu 3+ have\nbeen prepared. This paper reports on the major scintillation performances of\nthese compounds. One of them (Lu 2 O 3 :Eu) is particularly promising and have\nbeen deposited on a screen. Performances of such a screen are presented."
    },
    {
        "anchor": "Deformation Potentials and Electron-Phonon Coupling in Silicon Nanowires: The role of reduced dimensionality and of the surface on electron-phonon\n(e-ph) coupling in silicon nanowires is determined from first principles.\nSurface termination and chemistry is found to have a relatively small\ninfluence, whereas reduced dimensionality fundamentally alters the behavior of\ndeformation potentials. As a consequence, electron coupling to \"breathing\nmodes\" emerges that cannot be described by conventional treatments of e-ph\ncoupling. The consequences for physical properties such as scattering lengths\nand mobilities are significant: the mobilities for [110] grown wires are 6\ntimes larger than those for [100] wires, an effect that cannot be predicted\nwithout the form we find for Si nanowire deformation potentials.",
        "positive": "A van der Waals antiferromagnetic topological insulator with weak\n  interlayer magnetic coupling: Magnetic topological insulators (TI) provide an important material platform\nto explore quantum phenomena such as quantized anomalous Hall (QAH) effect and\nMajorana modes, etc. Their successful material realization is thus essential\nfor our fundamental understanding and potential technical revolutions. By\nrealizing a bulk van der Waals material MnBi4Te7 with alternating septuple\n[MnBi2Te4] and quintuple [Bi2Te3] layers, we show that it is ferromagnetic in\nplane but antiferromagnetic along the c axis with an out-of-plane saturation\nfield of ~ 0.22 T at 2 K. Our angle-resolved photoemission spectroscopy\nmeasurements and first-principles calculations further demonstrate that\nMnBi4Te7 is a Z2 antiferromagnetic TI with two types of surface states\nassociated with the [MnBi2Te4] or [Bi2Te3] termination, respectively.\nAdditionally, its superlattice nature may make various heterostructures of\n[MnBi2Te4] and [Bi2Te3] layers possible by exfoliation. Therefore, the low\nsaturation field and the superlattice nature of MnBi4Te7 make it an ideal\nsystem to investigate rich emergent phenomena."
    },
    {
        "anchor": "Unveiling the charge density wave mechanism in vanadium-based Bi-layered\n  kagome metals: The charge density wave (CDW), as a hallmark of vanadium-based kagome\nsuperconductor AV3Sb5 (A = K, Rb, Cs), has attracted intensive attention.\nHowever, the fundamental controversy regarding the underlying mechanism of CDW\ntherein persists. Recently, the vanadium-based bi-layered kagome metal ScV6Sn6,\nreported to exhibit a long-range charge order below 94 K, has emerged as a\npromising candidate to further clarify this core issue. Here, employing\nmicro-focusing angle-resolved photoemission spectroscopy ({\\mu}-ARPES) and\nfirst-principles calculations, we systematically studied the unique CDW order\nin vanadium-based bi-layered kagome metals by comparing ScV6Sn6 with its\nisostructural counterpart YV6Sn6, which lacks a CDW ground state. Combining\nARPES data and the corresponding joint density of states (DOS), we suggest that\nthe VHS nesting mechanism might be invalid in these materials. Besides, in\nScV6Sn6, we identified multiple hybridization energy gaps resulting from\nCDW-induced band folding, along with an anomalous band dispersion, implying a\npotential electron-phonon coupling driven mechanism underlying the formation of\nthe CDW order. Our finding not only comprehensively maps the electronic\nstructure of V-based bi-layer kagome metals but also provide constructive\nexperimental evidence for the unique origin of CDW in this system.",
        "positive": "Al4SiC4 w\u00fcrtzite crystal: structural, optoelectronic, elastic and\n  piezoelectric properties: New experimental results supported by theoretical analyses are proposed for\naluminum silicon carbide (Al4SiC4). A state of the art implementation of the\nDensity Functional Theory is used to analyze the experimental crystal\nstructure, the Born charges, the elastic and piezoelectric properties. The Born\ncharge tensor is correlated to the local bonding environment for each atom. The\nelectronic band structure is computed including self-consistent many-body\ncorrections. Al4SiC4 material properties are compared to other wide band gap\nW\\\"urtzite materials. From a comparison between an ellipsometry study of the\noptical properties and theoretical results, we conclude that the Al4SiC4\nmaterial has indirect and direct band gap energies of about 2.5eV and 3.2 eV\nrespectively."
    },
    {
        "anchor": "Reversible control of Co magnetism by voltage induced oxidation: We demonstrate that magnetic properties of ultra-thin Co films adjacent to\nGd2O3 gate oxides can be directly manipulated by voltage. The Co films can be\nreversibly changed from an optimally-oxidized state with a strong perpendicular\nmagnetic anisotropy to a metallic state with an in-plane magnetic anisotropy,\nor to an oxidized state with nearly zero magnetization, depending on the\npolarity and time duration of the applied electric fields. Consequently, an\nunprecedentedly large change of magnetic anisotropy energy up to 0.73 erg/cm2\nhas been realized in a nonvolatile manner using gate voltages of only a few\nvolts. These results open a new route to achieve ultra-low energy magnetization\nmanipulation in spintronic devices.",
        "positive": "Inter-valence charge transfer and charge transport in the spinel ferrite\n  ferromagnetic semiconductor Ru-doped CoFe$_2$O$_4$: Inter-valence charge transfer (IVCT) is electron transfer between two metal\n$M$ sites differing in oxidation states through a bridging ligand: $M^{n+1} +\nM'^{m} \\rightarrow M^{n} + M'^{m+1}$. It is considered that IVCT is related to\nthe hopping probability of electron (or the electron mobility) in solids. Since\ncontrolling the conductivity of ferromagnetic semiconductors (FMSs) is a key\nsubject for the development of spintronic device applications, the manipulation\nof the conductivity through IVCT may become a new approach of band engineering\nin FMSs. In Ru-doped cobalt ferrite CoFe$_2$O$_4$ (CFO) that shows\nferrimagnetism and semiconducting transport properties, the reduction of the\nelectric resistivity is attributed to both the carrier doping caused by the Ru\nsubstitution for Co and the increase of the carrier mobility due to\nhybridization between the wide Ru $4d$ and the Fe $3d$ orbitals. The latter is\nthe so-called IVCT mechanism that is charge transfer between the mixed valence\nFe$^{2+}$/Fe$^{3+}$ states facilitated by bridging Ru $4d$ orbital: Fe$^{2+}$ +\nRu$^{4+}$ $\\leftrightarrow$ Fe$^{3+}$ + Ru$^{3+}$. To elucidate the emergence\nof the IVCT state, we have conducted x-ray absorption spectroscopy (XAS) and\nresonant photoemission spectroscopy (RPES) measurements on non-doped CFO and\nCo$_{0.5}$Ru$_{0.5}$Fe$_2$O$_4$ (CRFO) thin films. The observations of the XAS\nand RPES spectra indicate that the presence of the mixed valence\nFe$^{2+}$/Fe$^{3+}$ state and the hybridization between the Fe $3d$ and Ru $4d$\nstates in the valence band. These results provide experimental evidence for the\nIVCT state in CRFO, demonstrating a novel mechanism that controls the electron\nmobility through hybridization between the $3d$ transition-metal cations with\nintervening $4d$ states."
    },
    {
        "anchor": "Coherent Exciton-Lattice Dynamics in a 2D Metal Organochalcogenolate\n  Semiconductor: Hybrid organic-inorganic nanomaterials can exhibit transitional behavior that\ndeviates from models developed for all-organic or all-inorganic materials\nsystems. Here, we reveal the complexity of exciton-phonon interactions in a\nrecently discovered 2D layered hybrid organic-inorganic semiconductor, silver\nphenylselenolate (AgSePh). Using femtosecond resonant impulsive vibrational\nspectroscopy and non-resonant Raman scattering, we measure multiple hybrid\norganic-inorganic vibrational modes and identify a subset of these modes that\nstrongly couple to the electronic excited state. Calculations by density\nfunctional perturbation theory show that these strongly coupled modes exhibit\nlarge out-of-plane silver atomic motions and silver-selenium spacing\ndisplacements. Moreover, analysis of photoluminescence fine-structure splitting\nand temperature-dependent peak-shifting/linewidth-broadening suggests that\nlight emission in AgSePh is most strongly affected by a compound 100 cm-1 mode\ninvolving the wagging motion of phenylselenolate ligands and accompanying\nmetal-chalcogen stretching. Finally, red-shifting of vibrational modes with\nincreasing temperature reveals a high degree of anharmonicity arising from\nnon-covalent interactions between phenyl rings. These findings reveal the\nunique effects of hybrid vibrational modes in organic-inorganic semiconductors\nand motivate future work aimed at specifically engineering such interactions\nthrough chemical and structural modification.",
        "positive": "Asperity contacts at the nanoscale: comparison of Ru and Au: We develop and validate an interatomic potential for ruthenium based on the\nembedded atom method framework with the Finnis/Sinclair representation. We\nconfirm that the new potential yields a stable hcp lattice with reasonable\nlattice and elastic constants and surface and stacking fault energies. We\nemploy molecular dynamics simulations to bring two surfaces together; one flat\nand the other with a single asperity. We compare the process of asperity\ncontact formation and breaking in Au and Ru, two materials currently in use in\nmicro electro mechanical system switches. While Au is very ductile at 150 and\n300 K, Ru shows considerably less plasticity at 300 and 600 K (approximately\nthe same homologous temperature). In Au, the asperity necks down to a single\natom thick bridge at separation. While similar necking occurs in Ru at 600 K,\nit is much more limited than in Au. On the other hand, at 300 K, Ru breaks by a\nmuch more brittle process of fracture/decohesion with limited plastic\ndeformation."
    },
    {
        "anchor": "Extremely high negative electron affinity of diamond via magnesium\n  adsorption: We report large negative electron affinity (NEA) on diamond (100) using\nmagnesium adsorption on a previously oxygen-terminated surface. The measured\nNEA is up to $(-2.01\\pm0.05)$ eV, the largest reported negative electron\naffinity to date. Despite the expected close relationship between the surface\nchemistry of Mg and Li species on oxygen-terminated diamond, we observe\ndifferences in the adsorption properties between the two. Most importantly, a\nhigh-temperature annealing step is not required to activate the Mg-adsorbed\nsurface to a state of negative electron affinity. Diamond surfaces prepared by\nthis procedure continue to possess negative electron affinity after exposure to\nhigh temperatures, air and even immersion in water.",
        "positive": "CoFeVSb: A Promising Candidate for Spin Valve and Thermoelectric\n  Applications: We report a combined theoretical and experimental study of a novel quaternary\nHeusler system CoFeVSb from the view point of room temperature spintronics and\nthermoelectric applications. It crystallizes in cubic structure with small\nDO$_3$-type disorder. The presence of disorder is confirmed by room temperature\nsynchrotron X-ray diffraction(XRD) and extended X-ray absorption fine structure\n(EXAFS) measurements. Magnetization data reveal high ordering temperature with\na saturation magnetization of 2.2 $\\mu_B$/f.u. Resistivity measurements reflect\nhalf-metallic nature. Double hysteresis loop along with asymmetry in the\nmagnetoresistance(MR) data reveals room temperature spin-valve feature, which\nremains stable even at 300 K. Hall measurements show anomalous behavior with\nsignificant contribution from intrinsic Berry phase. This compound also large\nroom temperature power factor ($\\sim0.62$ mWatt/m/K$^{2}$) and ultra low\nlattice thermal conductivity ($\\sim0.4$ W/m/K), making it a promising candidate\nfor thermoelectric application. Ab-initio calculations suggest weak\nhalf-metallic behavior and reduced magnetization (in agreement with experiment)\nin presence of DO$_3$ disorder. We have also found an energetically competing\nferromagnetic FM)/antiferromagnetic (AFM) interface structure within an\notherwise FM matrix: one of the prerequisites for spin valve behavior.\nCoexistence of so many promising features in a single system is rare, and hence\nCoFeVSb gives a fertile platform to explore numerous applications in future."
    },
    {
        "anchor": "Structural and Magnetic Properties of Sm(Co0.7Fe0.1Ni0.12Zr0.04B0.04)7.5\n  Melt Spun Isotropic and Anisotropic Ribbons: We have investigated the structural and magnetic properties of\nSm(Co0.7Fe0.1Ni0.12Zr0.04B0.04)7.5 melt spun ribbons. Samples were arc melted\nthen melt spun at 37 m/s up to 55 m/s to obtain ribbon for powdering. Annealing\nhas been performed in argon atmosphere for (30 to 75) min at (600 to 870) oC.\nIn as-spun ribbons the hexagonal SmCo7 (TbCu7-type of structure) of crystal\nstructure has been determined from x-ray diffraction patterns, while fcc-Co has\nbeen identified as a secondary phase. After annealing, the 1:7 phase of the\nas-spun ribbons transforms into 2:17 and 1:5 phases. X-ray patterns for\nas-milled powders exhibit very broad peaks making it difficult to identify a\nprecise structure but represent the 1:7 structure after annealing at low\ntemperature (650 oC). TEM analysis shows a homogeneous nanocrystalline\nmicrostructure with average grain size of (30 to 80) nm. Coercivity values of\n(15 to 27) kOe are obtained from hysteresis loops traced up to a field of 5 T.\nThe coercivity decreases as temperature increases, but it maintains values\nhigher than 5 kOe at 380 oC. The maximum energy product at room temperature\nincreases, as high as 7.2 MGOe, for melt-spun isotropic ribbons produced at\nhigher wheel speeds. Anisotropic ribbons have a maximum energy product close to\n12 MGOe.",
        "positive": "A Priori Approach to Calculation of Energies of Solvation: We propose a systematic, {\\em a priori} approach to the problem of the\ncalculation of solvation energies using continuum dielectric models coupled to\nquantum mechanical description of reacting molecules. Our method does not rely\non empirically scaled van der Waals radii to create a dielectric cavity, but\nrather uses the electron density of the reactants as the physical variable\ndescribing the cavity. In addition, the precise choice of cavity is made by\nensuring that the dielectric reproduces the correct linear response of the\nsolvent to electrostatic perturbations. As a model application which is\ninteresting in its own right, we study the hydrolysis of methylene chloride, a\nrepresentative model waste compound in supercritical oxidation experiments, and\nwhich has shown surprising solvation effects close to the critical point of\npure water (T=394$^o$ C, P=221 bar). Using our {\\em a priori} methodology, we\nfind results in good agreement with available experimental reaction barriers.\nWe then study, in a controlled manner, the relative importance of various\nfurther approximations that are routinely performed in the literature such as\nthe use of spherical cavities, the replacement of the reactant by a dipole, or\nthe neglect of self consistency in solving the electrostatic problem."
    },
    {
        "anchor": "Energy renormalization and Mott transition in n-GaAs and n-GaN: In this paper, we investigate renormalization of charge carrier effective\nmasses and bandgap narrowing in n-GaAs and wurtzite-type n-GaN over a wide\nrange of temperatures and dopant concentrations. The calculations are based on\nthe Green's function formalism. Contrary to the previous works, we consider the\nregions below as well as above the Mott transition. Special attention is paid\nto formation of donor subband and condition for the Mott transition. We also\ntake into account the effects caused by optical phonons. The latter strongly\ndepend on the doping level because of dynamic screening. It is shown that three\nspecific doping levels may be set off in n-GaN. They correspond to 1) Mott\ntransition, 2) resonance amplification of optical phonon-plasmon, and 3) full\ndynamic screening of optical phonons, respectively. Contrary to the case of\nn-GaN, the effect of full dynamic screening cannot be implemented in n-GaAs\nbecause of stronger nonparabolicity of conduction band.",
        "positive": "Te Doped Indium (II) Selenide Photocatalyst for Water Splitting: A First\n  Principles Study: Graphene like 2D materials have attracted tremendous attention in the field\nof photocatalytic water splitting. Indium Selenide (InSe) is one such potential\nmaterial. Here, we report the effect of Tellurium on InSe monolayer for the\nphotocatalytic water splitting by means of density functional calculations. The\ncalculated bandgaps fall within the visible region of the solar spectrum\nindicating these materials could absorb a significant amount of solar light.\nDensity of states calculations show that the covalent character is present\nbetween the atoms which is typical for the layered system. The band alignment\nwith respect to redox potentials show that Te doped InSe is more favorable for\nthe hydrogen reduction reaction than the pristine InSe monolayer. Our overall\nresults show that Te substitution improves the photocatalytic water splitting\nability in InSe monolayer."
    },
    {
        "anchor": "Flexo-diffusion effect: the strong influence on lithium diffusion\n  induced by strain gradient: Lithium ion batteries (LIBs) work under sophisticated external force field\nand its electrochemical properties could be modulated by strain. Owing to the\nelectro-mechanical coupling, the change of micro-local-structures can greatly\naffect lithium (Li) diffusion rate in solid state electrolytes and electrode\nmaterials of LIBs. In this study, we find that strain gradient in bilayer\ngraphene (BLG) significantly affects Li diffusion barrier, which is termed as\nthe flexo-diffusion effect, through first-principles calculations. The Li\ndiffusion barrier substantially decreases/increases under the positive/negative\nstrain gradient, leading to the change of Li diffusion coefficient in several\norders of magnitude at 300 K. Interestingly, the regulation effect of strain\ngradient is much more significant than that of uniform strain field, which can\nhave a remarkable effect on the rate performance of batteries, with a\nconsiderable increase in the ionic conductivity and a slight change of the\noriginal material structure. Moreover, our ab initio molecular dynamics\nsimulations (AIMD) show that the asymmetric distorted lattice structure\nprovides a driving force for Li diffusion, resulting in oriented diffusion\nalong the positive strain gradient direction. These findings could extend\npresent LIBs technologies by introducing the novel strain gradient engineering.",
        "positive": "Relevance of $4f$-$3d$ exchange to finite-temperature magnetism of\n  rare-earth permanent magnets: an ab-initio-based spin model approach for\n  NdFe$_{12}$N: A classical spin model derived ab initio for rare-earth-based permanent\nmagnet compounds is presented. Our target compound, NdFe$_{12}$N, is a material\nthat goes beyond today's champion magnet compound Nd$_{2}$Fe$_{14}$B in its\nintrinsic magnetic properties with a simpler crystal structure. Calculated\ntemperature dependence of the magnetization and the anisotropy field agree with\nthe latest experimental results in the leading order. Having put the realistic\nobservables under our numerical control, we propose that engineering\n$5d$-electron-mediated indirect exchange coupling between $4f$-electrons in Nd\nand $3d$-electrons from Fe would most critically help to enhance the material's\nutility over the operation-temperature range."
    },
    {
        "anchor": "A new model for the effective thermal conductivity of polycrystalline\n  solids: A new model for predicting the effective thermal conductivity of\npolycrystalline materials is presented. In contrast to existing models, our new\nmodel is based on the thin-interface description of grain boundaries (GBs) and\ntreats GBs as an autonomous phase with its own thermal conductivity. This\ntreatment allows the model to account for the effects of segregation/doping,\ninterface structural/phase transition, and interface decohesion on the\neffective thermal conductivity. finite-element simulations were performed to\nvalidate the new model. The simulations proved its higher accuracy compared to\nexisting models.",
        "positive": "Investigation of a possible electronic phase separation in the magnetic\n  semiconductors Ga$_{1-x}$Mn$_{x}$As and Ga$_{1-x}$Mn$_{x}$P by means of\n  fluctuation spectroscopy: We present systematic temperature-dependent resistance noise measurements on\na series of ferromagnetic Ga$_{1-x}$Mn$_{x}$As epitaxial thin films covering a\nlarge parameter space in terms of the Mn content $x$ and other variations\nregarding sample fabrication. We infer that the electronic noise is dominated\nby switching processes related to impurities in the entire temperature range.\nWhile metallic compounds with $x>2$ % do not exhibit any significant change in\nthe low-frequency resistance noise around the Curie temperature $T_\\mathrm{C}$,\nwe find indications for an electronic phase separation in films with $x<2$ % in\nthe vicinity of $T_\\mathrm{C}$, manifesting itself in a maximum in the noise\npower spectral density. These results are compared with noise measurements on\nan insulating Ga$_{1-x}$Mn$_{x}$P reference sample, for which the evidence for\nan electronic phase separation is even stronger and a possible percolation of\nbound magnetic polarons is discussed. Another aspect addressed in this work is\nthe effect of ion-irradiation induced disorder on the electronic properties of\nGa$_{1-x}$Mn$_{x}$As films and, in particular, whether any electronic\ninhomogeneities can be observed in this case. Finally, we put our findings into\nthe context of the ongoing debate on the electronic structure and the\ndevelopment of spontaneous magnetization in these materials."
    },
    {
        "anchor": "Hole-hole correlation effects on magnetic properties of\n  Mn$_x$III$_{1-x}$V diluted magnetic semiconductors: The mean-field theory represents a useful starting point for studying\ncarrier-induced ferromagnetism in Mn$_x$III$_{1-x}$V diluted magnetic\nsemiconductors. A detail description of these systems requires to include\ncorrelations in the many-body hole system. We discuss the effects of\ncorrelations among itinerant carriers on magnetic properties of bulk\nMn$_x$III$_{1-x}$V and magnetic semiconductor quantum wells. Presented results\nwere obtained using parabolic band approximation and we also derive a many-body\nperturbation technique that allows to account for hole-hole correlations in\nrealistic semiconductor valence bands.",
        "positive": "Review of Transition-Metal Diboride Thin Films: We review the thin film growth, chemistry, and physical properties of Group\n4-6 transition-metal diboride (TMB2) thin films with AlB2-type crystal\nstructure (Strukturbericht designation C32). Industrial applications are\ngrowing rapidly as TMB2 begin competing with conventional refractory ceramics\nlike carbides and nitrides, including pseudo-binaries such as Ti1-xAlxN. The\nTMB2 crystal structure comprises graphite-like honeycombed atomic sheets of B\ninterleaved by hexagonal close-packed TM layers. From the C32 crystal structure\nstems unique properties including high melting point, hardness, and corrosion\nresistance, yet limited oxidation resistance, combined with high electrical\nconductivity. We correlate the underlying chemical bonding, orbital overlap,\nand electronic structure to the mechanical properties, resistivity, and\nhigh-temperature properties unique to this class of materials. The review\nhighlights the importance of avoiding contamination elements (like oxygen) and\nboron segregation on both the target and substrate sides during sputter\ndeposition, for better-defined properties, regardless of the boride system\ninvestigated. This is a consequence of the strong tendency for B to segregate\nto TMB2 grain boundaries for boron-rich compositions of the growth flux. It is\njudged that sputter deposition of TMB2 films is at a tipping point towards a\nmultitude of applications for TMB2 not solely as bulk materials, but also as\nprotective coatings and electrically conducting high-temperature stable thin\nfilms."
    },
    {
        "anchor": "DFT calculations of magnetic anisotropy energy for GeMnTe ferromagnetic\n  semiconductor: Density functional theory (DFT) calculations of the energy of magnetic\nanisotropy for diluted ferromagnetic semiconductor GeMnTe were performed using\nusing OpenMX package with fully relativistic pseudopotentials. The influence of\nhole concentration and magnetic ion neighborhood on magnetic anisotropy energy\nis presented. Analysis of microscopic mechanism of magnetic anisotropy is\nprovided, in particular the role of spin-orbit coupling, spin polarization and\nspatial changes of electron density are discussed. The calculations are in\naccordance with the experimental observation of perpendicular magnetic\nanisotropy in rhombohedral GeMnTe (111) thin layers.",
        "positive": "Towards barrier free contact to MoS2 using graphene electrodes: The two-dimensional (2D) layered semiconductors such as MoS2 have attracted\ntremendous interest as a new class of electronic materials. However, there is\nconsiderable challenge in making reliable contacts to these atomically thin\nmaterials. Here we present a new strategy by using graphene as back electrodes\nto achieve Ohmic contact to MoS2. With a finite density of states, the Fermi\nlevel of graphene can be readily modified by gate potential to ensure a nearly\nperfect band alignment with MoS2. We demonstrate, for the first time, a\ntransparent contact can be made to MoS2 with essentially zero contact barrier\nand linear output behaviour at cryogenic temperatures (down to 1.9 K) for both\nmonolayer and multilayer MoS2. Benefiting from the barrier-free transparent\ncontacts, we show that a metal-insulator-transition (MIT) can be observed in a\ntwo-terminal MoS2 device, a phenomenon that could be easily masked by Schottky\nbarrier and only seen in four-terminal devices in conventional metal-contacted\nMoS2 system. With further passivation y born nitride encapsulation, we\ndemonstrate a record high extrinsic (two-terminal) field effect mobility over\n1300 cm2/Vs in MoS2."
    },
    {
        "anchor": "Anomalous phonon lifetime shortening in paramagnetic CrN caused by\n  magneto-lattice coupling: A combined spin and ab initio molecular dynamics\n  study: We study the mutual coupling of spin fluctuations and lattice vibrations in\nparamagnetic CrN by combining atomistic spin dynamics and ab initio molecular\ndynamics. The two degrees of freedom are dynamically coupled leading to\nnon-adiabatic effects. Those effects suppress the phonon life times at low\ntemperature compared to an adiabatic approach. The here identified dynamic\ncoupling provides an explanation for the experimentally observed unexpected\ntemperature dependence of the thermal conductivity of magnetic semiconductors\nabove the magnetic ordering temperature.",
        "positive": "Crystallization in Three-Dimensions: Defect-Driven Topological Ordering\n  and the Role of Geometrical Frustration: Herein, fundamentals of topology and symmetry breaking are used to understand\ncrystallization and geometrical frustration in topologically close-packed\nstructures. This frames solidification from a new perspective that is unique\nfrom thermodynamic discussions. Crystallization is considered as developing\nfrom undercooled liquids, in which orientational order is characterized by a\nsurface of a sphere in four-dimensions (quaternion) with the binary polyhedral\nrepresentation of the preferred orientational order of atomic clustering\ninscribed on its surface. As a consequence of the dimensionality of the\nquaternion orientational order parameter, crystallization is seen as occurring\nin \"restricted dimensions.\" Homotopy theory is used to classify all\ntopologically stable defects, and third homotopy group defect elements are\nconsidered to be generalized vortices that are available in superfluid ordered\nsystems. This topological perspective approaches the liquid-to-crystalline\nsolid transition in three-dimensions from fundamental concepts of:\nBose-Einstein condensation, the Mermin-Wagner theorem and\nBerezinskii-Kosterlitz-Thouless (BKT) topological-ordering transitions. In\ndoing so, in this article, concepts that apply to superfluidity in \"restricted\ndimensions\" are generalized in order to consider the solidification of\ncrystalline solid states."
    },
    {
        "anchor": "Enhancement of optical switching parameter and third-order optical\n  nonlinearities in embedded Si nanocrystals: a theoretical assessment: Third-order bound-charge electronic nonlinearities of Si nanocrystals (NCs)\nembedded in a wide band-gap matrix representing silica are theoretically\nstudied using an atomistic pseudopotential approach. Nonlinear refractive\nindex, two-photon absorption and optical switching parameter are examined from\nsmall clusters to NCs up to a size of 3 nm. Compared to bulk values, Si NCs\nshow higher third-order optical nonlinearities and much wider two-photon\nabsorption threshold which gives rise to enhancement in the optical switching\nparameter.",
        "positive": "Thermal stability of coupled ferromagnetic and superparamagnetic\n  particles: We consider a single-domain ferromagnetic particle with uniaxial anisotropy\ncoupled to a single-domain soft ferromagnetic particle (superparamagnetic\nparticle). The problem of thermally agitated magnetization reversal in this\ncase can be reduced to the random magnetization dynamics of the first particle\nwith an effectively larger anisotropy field. The magnetic external field is\nalso altered in a manner that depends on the sign of the coupling and can be\neither enhanced or suppressed."
    },
    {
        "anchor": "Soft topological lattice wheels: We investigate the large deformation and extreme load-management capabilities\nof a soft topologically polarized kagome lattice mapped to a cylindrical domain\nthrough the problem of a lattice wheel rolling on an irregular surface. We test\nthe surface-lattice interaction experimentally by subjecting a 3D-printed\ntopological lattice wheel prototype to localized and distributed boundary\nloads. This investigation reveals a dichotomy in the force transfer between the\ntwo loading scenarios, whereby localized loads are absorbed with limited stress\npenetration into the bulk and small force transfer to the wheel axle, compared\nto distributed loads. Through numerical simulations, we compare the lattice\nwheel against a baseline solid wheel to highlight the unique stress management\nopportunities offered by the lattice configuration. These findings promote the\ndesign of rolling objects enabled by topological mechanics, in which a surplus\nof softness, activated by local asperities, can coexist with a globally stiff\nresponse to distributed loads that ensures satisfactory load-bearing\ncapabilities.",
        "positive": "Switching the magnetic configuration of a spin valve by current induced\n  domain wall motion: We present experimental results on the displacement of a domain wall by\ninjection of a dc current through the wall. The samples are 1 micron wide long\nstripes of a CoO/Co/Cu/NiFe classical spin valve structure.\n  The stripes have been patterned by electron beam lithography. A neck has been\ndefined at 1/3 of the total length of the stripe and is a pinning center for\nthe domain walls, as shown by the steps of the giant magnetoresistance curves\nat intermediate levels (1/3 or 2/3) between the resistances corresponding to\nthe parallel and antiparallel configurations. We show by electric transport\nmeasurements that, once a wall is trapped, it can be moved by injecting a dc\ncurrent higher than a threshold current of the order of magnitude of 10^7\nA/cm^2. We discuss the different possible origins of this effect, i.e. local\nmagnetic field created by the current and/or spin transfer from spin polarized\ncurrent."
    },
    {
        "anchor": "Fundamental hydrogen storage properties of TiFe-alloy with partial\n  substitution of Fe by Ti and Mn: TiFe intermetallic compound has been extensively studied, owing to its low\ncost, good volumetric hydrogen density, and easy tailoring of hydrogenation\nthermodynamics by elemental substitution. All these positive aspects make this\nmaterial promising for large-scale applications of solid-state hydrogen\nstorage. On the other hand, activation and kinetic issues should be amended and\nthe role of elemental substitution should be further understood. This work\ninvestigates the thermodynamic changes induced by the variation of Ti content\nalong the homogeneity range of the TiFe phase (Ti:Fe ratio from 1:1 to 1:0.9)\nand of the substitution of Mn for Fe between 0 and 5 at.%. In all considered\nalloys, the major phase is TiFe-type together with minor amounts of TiFe2 or\n\\b{eta}-Ti-type and Ti4Fe2O-type at the Ti-poor and rich side of the TiFe phase\ndomain, respectively. Thermodynamic data agree with the available literature\nbut offer here a comprehensive picture of hydrogenation properties over an\nextended Ti and Mn compositional range. Moreover, it is demonstrated that\nTi-rich alloys display enhanced storage capacities, as long as a limited amount\nof \\b{eta}-Ti is formed. Both Mn and Ti substitutions increase the cell\nparameter by possibly substituting Fe, lowering the plateau pressures and\ndecreasing the hysteresis of the isotherms. A full picture of the dependence of\nhydrogen storage properties as a function of the composition will be discussed,\ntogether with some observed correlations.",
        "positive": "Viscosity of Cobalt Melt: Experiment, Simulation, and Theory: The results of experimental measurements, molecular dynamics simulation, and\ntheoretical calculations of the viscosity of a cobalt melt in a temperature\nrange of $1400-2000$~K at a pressure $p=1.5$~bar corresponding to an overcooled\nmelt at temperatures of $1400-1768$~K and an equilibrium melt with temperatures\nfrom the range $1768-2000$~K are presented. Theoretical expressions for the\nspectral density of the time-dependent correlation function of the stress\ntensor $\\tilde{S}(\\omega)$ and kinematic viscosity $\\nu$ determined from the\nfrequency and thermodynamic parameters of the system are obtained. The\ntemperature dependences of the kinematic viscosity for the cobalt melt are\ndetermined experimentally by the torsional oscillation method; numerically,\nbased on molecular simulation data with the EAM potential via subsequent\nanalysis of the time correlation functions of the transverse current in the\nframework of generalized hydrodynamics; and by the integral Kubo-Green\nrelation; they were also determined theoretically with the Zwanzig-Mori memory\nfunctions formalism using a self-consistent approach. Good agreement was found\nbetween the results of theoretical calculations for the temperature dependence\nof the kinematic viscosity of the cobalt melt using experimental data and the\nmolecular dynamics simulation results. From an analysis of the temperature\ndependence of the viscosity, we obtain an activation energy of\n$E=(5.38\\pm0.02)\\times10^{-20}$~J."
    },
    {
        "anchor": "Tunable charge-trap memory based on few-layer MoS2: Charge-trap memory with high-\\k dielectric materials is considered to be a\npromising candidate for next-generation memory devices. Ultrathin layered\ntwo-dimensional (2D) materials like graphene and MoS2 have been receiving much\nattention because of their novel physical properties and potential applications\nin electronic devices. Here, we report on a dual-gate charge-trap memory device\ncomposed of a few-layer MoS2 channel and a three-dimensional (3D)\nAl2O3/HfO2/Al2O3 charge-trap gate stack. Owing to the extraordinary trapping\nability of both electrons and holes in HfO2, the MoS2 memory device exhibits an\nunprecedented memory window exceeding 20 V. More importantly, with a back gate\nthe window size can be effectively tuned from 15.6 to 21 V; the program/erase\ncurrent ratio can reach up to 104, far beyond Si-based flash memory, which\nallows for multi-bit information storage. Furthermore, the device shows a high\nmobility of 170 cm2V-1s-1, a good endurance of hundreds of cycles and a stable\nretention of ~28% charge loss after 10 years which is drastically lower than\never reported MoS2 flash memory. The combination of 2D materials with\ntraditional high-\\k charge-trap gate stacks opens up an exciting field of novel\nnonvolatile memory devices.",
        "positive": "Database of Wannier Tight-binding Hamiltonians using High-throughput\n  Density Functional Theory: We develop a computational workflow for high-throughput Wannierization of\ndensity functional theory (DFT) based electronic band structure calculations.\nWe apply this workflow to 1771 materials, and we create a database with the\nresulting Wannier-function based tight binding Hamiltonians (WTBH). We evaluate\nthe accuracy of the WTBHs by comparing the Wannier band structures to directly\ncalculated DFT band structures on both the set of k-points used in the\nWannierization as well as independent k-points from high symmetry lines.\nAccurate WTBH can be used for the calculation of many materials properties, and\nwe include a few example applications. We also develop a web-app that can be\nused to predict electronic properties on-the-fly using WTBH from our database.\nThe tools to generate the Hamiltonian and the database of the WTB parameters\nwill be made publicly available through the websites\nhttps://github.com/usnistgov/jarvis and https://www.ctcms.nist.gov/jarviswtb."
    },
    {
        "anchor": "Chain-oxygen ordering in twin-free YBa2Cu3O6+x single crystals driven by\n  20 keV electron irradiation: We have examined the effects of 20 keV electron irradiation on\n[-Cu(1)-O(1)-]n chain oxygen arrangements in oxygen deficient but otherwise\ntwin-free YBa2Cu3O6+x single crystals. Comparison of polarized Raman spectra of\nnon-irradiated and irradiated areas provides evidence that electron\nbombardments instigate the collective hopping of oxygen atoms either from an\ninterstitial at O(5) site to a vacant O(1) chain site or by reshuffling the\nchain segments to extend the average length of chains without changing the\noverall oxygen content. This oxygen ordering effect, while counter-intuitive,\nis analogous to that found in the photoexcitation induced ordering in which\ntemporal charge imbalance from electron-hole pair creation by inelastic\nscattering of incident electrons causes a local lattice distortion which brings\non the atomic rearrangements.",
        "positive": "Non-ohmic spin transport in n-type doped silicon: We demonstrate the injection and transport of spin-polarized electrons\nthrough n-type doped silicon with in-plane spin-valve and perpendicular\nmagnetic field spin precession and dephasing (\"Hanle effect\") measurements. A\nvoltage applied across the transport layer is used to vary the confinement\npotential caused by conduction band-bending and control the dominant transport\nmechanism between drift and diffusion. By modeling transport in this device\nwith a Monte-Carlo scheme, we simulate the observed spin polarization and Hanle\nfeatures, showing that the average transit time across the short Si transport\nlayer can be controlled over 4 orders of magnitude with applied voltage. As a\nresult, this modeling allows inference of a long electron spin lifetime,\ndespite the short transit length."
    },
    {
        "anchor": "Breathing pyrochlore magnet CuGaCr$_{4}$S$_{8}$: Magnetic,\n  thermodynamic, and dielectric properties: We investigate the crystallographic and magnetic properties of a\nchromium-based thiospinel CuGaCr$_{4}$S$_{8}$. From a synchrotron x-ray\ndiffraction experiment and structural refinement, Cu and Ga atoms are found to\noccupy the tetrahedral $A$-sites in an alternate way, yielding breathing\npyrochlore Cr network. CuGaCr$_{4}$S$_{8}$ undergoes a magnetic transition\nassociated with a structural distortion at 31 K in zero magnetic field,\nindicating that the spin-lattice coupling is responsible for relieving the\ngeometrical frustration. When applying a pulsed high magnetic field, a sharp\nmetamagnetic transition takes place at 40 T, followed by a 1/2-magnetization\nplateau up to 103 T. These phase transitions accompany dielectric anomalies,\nsuggesting the presence of helical spin correlations in low-field phases. The\ndensity-functional-theory calculation reveals that CuGaCr$_{4}$S$_{8}$ is\ndominated by antiferromagnetic and ferromagnetic exchange couplings within\nsmall and large tetrahedra, respectively, in analogy with CuInCr$_{4}$S$_{8}$.\nWe argue that $A$-site-ordered Cr thiospinels serve as an excellent platform to\nexplore diverse magnetic phases along with pronounced magnetoelastic and\nmagnetodielectric responses.",
        "positive": "Compression Behavior of Single-layer Graphene: Central to most applications involving monolayer graphene is its mechanical\nresponse under various stress states. To date most of the work reported is of\ntheoretical nature and refers to tension and compression loading of model\ngraphene. Most of the experimental work is indeed limited to bending of single\nflakes in air and the stretching of flakes up to typically ~1% using plastic\nsubstrates. Recently we have shown that by employing a cantilever beam we can\nsubject single graphene into various degrees of axial compression. Here we\nextend this work much further by measuring in detail both stress uptake and\ncompression buckling strain in single flakes of different geometries. In all\ncases the mechanical response is monitored by simultaneous Raman measurements\nthrough the shift of either the G or 2D phonons of graphene. In spite of the\ninfinitely small thickness of the monolayers, the results show that graphene\nembedded in plastic beams exhibit remarkable compression buckling strains. For\nlarge length (l)-to-width (w) ratios (> 0.2) the buckling strain is of the\norder of -0.5% to -0.6%. However, for l/w <0.2 no failure is observed for\nstrains even higher than -1%. Calculations based on classical Euler analysis\nshow that the buckling strain enhancement provided by the polymer lateral\nsupport is more than six orders of magnitude compared to suspended graphene in\nair."
    },
    {
        "anchor": "Training-free hyperparameter optimization of neural networks for\n  electronic structures in matter: A myriad of phenomena in materials science and chemistry rely on\nquantum-level simulations of the electronic structure in matter. While moving\nto larger length and time scales has been a pressing issue for decades, such\nlarge-scale electronic structure calculations are still challenging despite\nmodern software approaches and advances in high-performance computing. The\nsilver lining in this regard is the use of machine learning to accelerate\nelectronic structure calculations -- this line of research has recently gained\ngrowing attention. The grand challenge therein is finding a suitable\nmachine-learning model during a process called hyperparameter optimization.\nThis, however, causes a massive computational overhead in addition to that of\ndata generation. We accelerate the construction of neural network models by\nroughly two orders of magnitude by circumventing excessive training during the\nhyperparameter optimization phase. We demonstrate our workflow for Kohn-Sham\ndensity functional theory, the most popular computational method in materials\nscience and chemistry.",
        "positive": "Approaching a Minimal Topological Electronic Structure in\n  Antiferromagnetic Topological Insulator MnBi2Te4 via Surface Modification: The topological electronic structure plays a central role in the non-trivial\nphysical properties in topological quantum materials. A minimal,\nhydrogen-atom-like topological electronic structure is desired for researches.\nIn this work, we demonstrate an effort towards the realization of such a system\nin the intrinsic magnetic topological insulator MnBi2Te4, by manipulating the\ntopological surface state (TSS) via surface modification. Using high resolution\nlaser- and synchrotron-based angle-resolved photoemission spectroscopy (ARPES),\nwe found the TSS in MnBi2Te4 is heavily hybridized with a trivial Rashba-type\nsurface state (RSS), which could be efficiently removed by the in situ surface\npotassium (K) dosing. By employing multiple experimental methods to\ncharacterize K dosed surface, we attribute such a modification to the\nelectrochemical reactions of K clusters on the surface. Our work not only gives\na clear band assignment in MnBi2Te4, but also provides possible new routes in\naccentuating the topological behavior in the magnetic topological quantum\nmaterials."
    },
    {
        "anchor": "A Systematic Study of Chloride Ion Solvation in Water using van der\n  Waals Inclusive Hybrid Density Functional Theory: In this work, the solvation and electronic structure of the aqueous chloride\nion solution was investigated using Density Functional Theory (DFT) based\n\\textit{ab initio} molecular dynamics (AIMD). From an analysis of radial\ndistribution functions, coordination numbers, and solvation structures, we\nfound that exact exchange ($E_{\\rm xx}$) and non-local van der Waals (vdW)\ninteractions effectively \\textit{weaken} the interactions between the Cl$^-$\nion and the first solvation shell. With a Cl-O coordination number in excellent\nagreement with experiment, we found that most configurations generated with\nvdW-inclusive hybrid DFT exhibit 6-fold coordinated distorted trigonal prism\nstructures, which is indicative of a significantly disordered first solvation\nshell. By performing a series of band structure calculations on configurations\ngenerated from AIMD simulations with varying DFT potentials, we found that the\nsolvated ion orbital energy levels (unlike the band structure of liquid water)\nstrongly depend on the underlying molecular structures. In addition, these\norbital energy levels were also significantly affected by the DFT functional\nemployed for the electronic structure; as the fraction of $E_{\\rm xx}$ was\nincreased, the gap between the highest occupied molecular orbital of Cl$^-$ and\nthe valence band maximum of liquid water steadily increased towards the\nexperimental value.",
        "positive": "Quantifying the Topology of Magnetic Skyrmions in three Dimensions: Magnetic skyrmions have so far been treated as two-dimensional spin\nstructures characterized by a topological winding number describing the\nrotation of spins across the skyrmion. However, in real systems with a finite\nthickness of the material being larger than the magnetic exchange length, the\nskyrmion spin texture extends into the third dimension and cannot be assumed as\nhomogeneous. Using soft x-ray laminography we reconstruct with about 20nm\nspatial (voxel) resolution the full three-dimensional spin texture of a\nskyrmion in an 800 nm diameter and 95 nm thin disk patterned into a trilayer\n[Ir/Co/Pt] thin film structure. A quantitative analysis finds that the\nevolution of the radial profile of the topological skyrmion number and the\nchirality is non-uniform across the thickness of the disk. Estimates of local\nmicromagnetic energy densities suggest that the changes in topological profile\nare related to non-uniform competing energetic interactions. Theoretical\ncalculations and micromagnetic simulations are consistent with the experimental\nfindings. Our results provide the foundation for nanoscale magnetic metrology\nfor future tailored spintronics devices using topology as a design parameter,\nand have the potential to reverse-engineer a spin Hamiltonian from macroscopic\ndata, tying theory more closely to experiment."
    },
    {
        "anchor": "Zeeman effect in centrosymmetric antiferromagnets controlled by an\n  electric field: Centrosymmetric antiferromagnetic semiconductors, although abundant in\nnature, seem less promising than ferromagnets and ferroelectrics for practical\napplications in semiconductor spintronics. As a matter of fact, the lack of\nspontaneous polarization and magnetization hinders the efficient utilization of\nelectronic spin in these materials. Here, we propose a paradigm to harness\nelectronic spin in centrosymmetric antiferromagnets via Zeeman spin splittings\nof electronic energy levels -- termed as spin Zeeman effect -- which is\ncontrolled by electric field.By symmetry analysis, we identify twenty-one\ncentrosymmetric antiferromagnetic point groups that accommodate such a spin\nZeeman effect. We further predict by first-principles that two\nantiferromagnetic semiconductors, Fe$_2$TeO$_6$ and SrFe$_2$S$_2$O, are\nexcellent candidates showcasing Zeeman splittings as large as $\\sim$55 and\n$\\sim$30 meV, respectively, induced by an electric field of 6 MV/cm. Moreover,\nthe electronic spin magnetization associated to the splitting energy levels can\nbe switched by reversing the electric field. Our work thus sheds light on the\nelectric-field control of electronic spin in antiferromagnets, which broadens\nthe scope of application of centrosymmetric antiferromagnetic semiconductors.",
        "positive": "Character of the Dislocation Bands in the (A+B) regime of the\n  Portevin-Le Chatelier effect in Al-2.5%Mg alloy: The Portevin-Le Chatelier(PLC) effect has been investigated by deforming\nAl-2.5%Mg alloy in the strain rate regime where simultaneously two types (type\nB and type A) of serrations appear in the stress strain curve. Our analysis\nreveal that in this strain rate regime the entire PLC dynamics for a particular\nstrain rate experiment is governed by a single band which changes its character\nduring the deformation."
    },
    {
        "anchor": "Boson peak dynamics of glassy glucose studied by integrated\n  terahertz-band spectroscopy: We performed terahertz time-domain spectroscopy, low-frequency Raman\nscattering, and Brillouin light scattering on vitreous glucose to investigate\nthe boson peak (BP) dynamics. In the spectra of {\\alpha}({\\nu})/{\\nu}2\n[{\\alpha}({\\nu}) is the absorption coefficient], the BP is clearly observed\naround 1.1 THz. Correspondingly, the complex dielectric constant spectra show a\nuniversal resonancelike behavior only below the BP frequency. As an analytical\nscheme, we propose the relative light-vibration coupling coefficient (RCC),\nwhich is obtainable from the combination of the far-infrared and Raman spectra.\nThe RCC reveals that the infrared light-vibration coupling coefficient\nCIR({\\nu}) of the vitreous glucose behaves linearly on frequency which deviates\nfrom Taraskin's model of CIR({\\nu}) = A + B{\\nu}2 [S. N. Taraskin et al., Phys.\nRev. Lett. 97, 055504 (2006)]. The linearity of CIR({\\nu}) might require\nmodification of the second term of the model. The measured transverse sound\nvelocity shows an apparent discontinuity with the flattened mode observed in\nthe inelastic neutron scattering study [N. Violini et al., Phys. Rev. B 85,\n134204 (2012)] and suggests a coupling between the transverse acoustic and\nflattened modes.",
        "positive": "Atomistic mechanisms governing structural stability change of zinc\n  antimony thermoelectrics: The structural stability of thermoelectric materials is a subject of growing\nimportance for their energy harvesting applications. Here, we study the\nmicroscopic mechanisms governing the structural stability change of zinc\nantimony at its working temperature, using molecular dynamics combined with\nexperimental measurements of the electrical and thermal conductivity. Our\nresults show that the temperature-dependence of the thermal and electrical\ntransport coefficients is strongly correlated with a structural transition.\nThis is found to be associated with a relaxation process, in which a group of\nZn atoms migrates between interstitial sites. This atom migration gradually\nleads to a stabilizing structural transition of the entire crystal framework,\nand then results in a more stable crystal structure of $\\beta-$ Zn4Sb3 at high\ntemperature."
    },
    {
        "anchor": "Compensation Behavior and Magnetic Properties of a Core/Shell Double\n  Fullerene Structure: In This work, we apply the Monte Carlo simulations to study the magnetic\nproperties and compensation behavior of a core/shell double fullerene structure\nX_60 where the symbol X can be assigned to any magnetic atom. We focus our\nstudy on a system formed by a double sphere forming a core-shell. The two\nspheres are containing the spins: S=1/2 in the core; and {\\sigma}=1 in the\nshell, respectively. In a first step, we investigate and discuss the\ncorresponding ground state phase diagrams in different planes. Also, we\nillustrated the behavior of the magnetizations and the effect of the coupling\nexchange interactions as well as the crystal field. The effect of the external\nmagnetic field, and the exchange coupling interactions on the hysteresis loops\nhave been inspected. To complete this study, we showed the existence of the\ncompensation temperature for the studied system.",
        "positive": "Modeling of high-efficiency silicon solar cells in realistic operating\n  conditions: The selfconsistent model for the temperature dependence of photoconversion\nefficiency $\\eta$ for highly efficient silicon solar cells (SCs) is developed.\nIt is demonstrated that effect of the efficiency decrease due to increasing\ntemperature is less pronounced in the SCs with lower surface recombination\nvelocity, thus offering a possibility to improve the cells' performance.\n  The photoconversion efficiency of the high efficiency silicon solar cells is\nmodeled for the realistic ambient conditions. The SC operating temperature is\ndetermined by self-consistently solving the photocurrent, photovoltage, and\nenergy balance equations, considering both radiative and convective cooling\nmechanisms. The SC temperature is shown to be substantially higher than the\nambient temperature even at very high convection coefficients, such as, e.g.,\n300 $W / (m^2 \\cdot K)$, used in our examples. The photoconversion efficiency\nfor this case is substantially below the efficiency of thermally stabilized SC,\nfor which the operating temperature is close to the external temperature.\n  The open-circuit voltage and photoconversion efficiency of the high-quality\nsilicon solar cells under concentrated illumination are also investigated\nincluding the tradeoff between SCs heating and cooling processes."
    },
    {
        "anchor": "Intrinsic ultralow lattice thermal conductivity of the unfilled\n  skutterudite FeSb$_3$: It has been generally accepted that unfilled skutterudites process high\nlattice thermal conductivity ($\\kappa_{l}$) that can be efficiently reduced\nupon filling. Here by using first principles Boltzmann-Peierls transport\ncalculations, we find pure skutterudite of FeSb$_3$ with no filler in fact has\nan intrinsic ultralow $\\kappa_{l}$ smaller than that of CoSb$_3$ by one order\nof magnitude. The value is even smaller than those of most of the fully filled\nskutterudites. This finding means that with FeSb$_3$ as a reference, filling\ndoes not necessarily lower $\\kappa_{l}$. The ultralow $\\kappa_{l}$ of FeSb$_3$\nis a consequence of much softened optical phonon branches associated with the\nweakly bonded Sb$_4$ rings. They overlap more with heat-carrying acoustic\nphonons and significantly increase the phase space for three-phonon anharmonic\nscattering processes. This provides an alternative non-filling related\nmechanism for lowering the $\\kappa_{l}$ of skutterudites.",
        "positive": "Ordering in a fibrinogen layer: Ordered protein layers are the subject of active biomedical research for\ntheir usually interesting physicochemical properties, e.g. permeability,\nstiffness and pours structure. In presented work, we focused on layers build of\nfibrinogen molecules characterised by strong shape anisotropy. Using Random\nSequential Adsorption (RSA) method, we simulated adsorption process in which\nthe orientation of adsorbate was described by a non-uniform probability\ndistribution. Thus obtained covering layers had different level of global\norientational ordering. This allowed us to find dependence between main\nproperties of layers, such as maximal random coverage ratio, and order\nparameter. For better description and deeper understanding of obtained\nstructures, the autocorrelation function as well as distribution of uncovered\nspace were determined. Additionally, we calculated the Available Surface\nFunction (ASF), which is essential for determining adsorption kinetics."
    },
    {
        "anchor": "Nanostructure and related mechanical properties of an Al-Mg-Si alloy\n  processed by severe plastic deformation: Microstructural features and mechanical properties of an Al-Mg-Si alloy\nprocessed by high-pressure torsion have been investigated using transmission\nelectron microscopy, X-ray diffraction, three-dimensional atom probe, tensile\ntests and microhardness measurements. It is shown that HPT processing of the\nAl-Mg-Si alloy leads to a much stronger grain size refinement than of pure\naluminium (down to 100 nm). Moreover, massive segregation of alloying elements\nalong grain boundaries is observed. This nanostructure exhibits a yield stress\neven two times higher than that after a standard T6 heat treatment of the\ncoarse grained alloy",
        "positive": "Non-volatile ferroelastic switching of the Verwey transition and\n  resistivity of epitaxial Fe3O4/PMN-PT (011): A central goal of electronics based on correlated materials or 'Mottronics'\nis the ability to switch between distinct collective states with a control\nvoltage. Small changes in structure and charge density near a transition can\ntip the balance between competing phases, leading to dramatic changes in\nelectronic and magnetic properties. In this work, we demonstrate that an\nelectric field induced two-step ferroelastic switching pathway in (011)\noriented 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 (PMN-PT) substrates can be used to\ntune the Verwey metal-insulator transition in epitaxial Fe3O4 films in a stable\nand reversible manner. We also observe robust non-volatile resistance switching\nin Fe3O4 up to room temperature, driven by ferroelastic strain. These results\nprovides a framework for realizing non-volatile and reversible tuning of order\nparameters coupled to lattice-strain in epitaxial oxide heterostructures over a\nbroad range of temperatures, with potential device applications."
    },
    {
        "anchor": "The geometry of C_60: a rigorous approach via Molecular Mechanics: Molecular Mechanics describes molecules as particle configurations\ninteracting via classical potentials. These {\\it configurational energies}\nusually consist of the sum of different phenomenological terms which are\ntailored to the description of specific bonding geometries. This approach is\nfollowed here to model the fullerene $C_{60}$, an allotrope of carbon\ncorresponding to a specific hollow spherical structure of sixty atoms. We\nrigorously address different modeling options and advance a set of minimal\nrequirements on the configurational energy able to deliver an accurate\nprediction of the fine three-dimensional geometry of $C_{60}$ as well as of its\nremarkable stability. In particular, the experimentally observed\ntruncated-icosahedron structure with two different bond lengths is shown to be\na strict local minimizer.",
        "positive": "A Strategy for Improving the Interfacial Crystallinity and Carrier\n  Mobility of SnO2 Porous Nanosolids: SnO2 porous nanosolid (PNS) was prepared by a solvothermal hot-press method,\nand a new strategy was developed to improve its interfacial crystallinity and\ncarrier mobility. It was found that the carrier mobility of SnO2 PNS was\nimproved after being calcined at 500 {\\deg}C in high-pressure oxygen.\nFurthermore, the mobility was greatly increased by calcining SnO2 PNS at 350\n{\\deg}C for 12 h in high-pressure oxygen, and the highest mobility reached 35\ncm2/Vs. On the other hand, the complex impedance spectra of the samples\nrevealed that the annihilation of oxygen vacancies mainly happens within the\ninterfacial region among SnO2 nanoparticles during the calcinations process in\nhigh-pressure oxygen. As a result, the interfacial crystallinity was improved\nand carrier mobility was increased. Based on the analysis of experimental data,\na simple model was proposed to explain the above phenomena. And the simple\nmodel may find applications in improving the carrier mobility of other oxide\nsemiconductors used in photovoltaic cells."
    },
    {
        "anchor": "Polarization switching induced by domain wall sliding in two-dimensional\n  ferroelectric monochalcogenides: The ability to switch between distinct states of polarization comprises the\ndefining property of ferroelectrics. However, the microscopic mechanism\nresponsible for switching is not well understood and theoretical estimates\nbased on coherent monodomain switching typically overestimate experimentally\ndetermined coercive fields by orders of magnitude. In this work we present a\ndetailed first principles characterization of domain walls (DWs) in\ntwo-dimensional ferroelectric GeS, GeSe, SnS and SnSe. In particular, we\ncalculate the formation energies and migration barriers for 180 and 90 DWs, and\nthen derive a general expression for the coercive field assuming that\npolarization switching is mediated by DW migration. We apply our approach to\nthe materials studied and obtain good agreement with experimental coercive\nfields. The calculated coercive fields are up to two orders of magnitude\nsmaller than those predicted from coherent monodomain switching in GeSe, SnS\nand SnSe. Finally, we study the optical properties of the compounds and find\nthat the presence of 180 DWs leads to a significant red shift of the absorption\nspectrum, implying that the density of DWs may be determined by means of simple\noptical probes.",
        "positive": "Adsorption Sites of Individual Metal Atoms on Ultrathin MgO(100) Films: We use Ca doping during growth of one and two monolayer thick MgO films on\nAg(100) to identify the adsorption sites of individual adatoms with scanning\ntunneling microscopy. For this we combine atomic resolution images of the bare\nMgO layer with images of the adsorbates and the substitutional Ca atoms taken\nat larger tip-sample distance. For Ho atoms, the adsorption sites depend on MgO\nthickness. On the monolayer, they are distributed on the O and bridge sites\naccording to the abundance of those sites, 1/3 and 2/3 respectively. On the MgO\nbilayer, Ho atoms populate almost exclusively the O site. A third species\nadsorbed on Mg is predicted by density functional theory and can be created by\natomic manipulation. Au atoms adsorb on the bridge sites for both MgO\nthicknesses, while Co and Fe atoms prefer the O sites, again for both\nthickness."
    },
    {
        "anchor": "Electrical and thermal spin accumulation in germanium: In this letter, we first show electrical spin injection in the germanium\nconduction band at room temperature and modulate the spin signal by applying a\ngate voltage to the channel. The corresponding signal modulation agrees well\nwith the predictions of spin diffusion models. Then by setting a temperature\ngradient between germanium and the ferromagnet, we create a thermal spin\naccumulation in germanium without any tunnel charge current. We show that\ntemperature gradients yield larger spin accumulations than pure electrical spin\ninjection but, due to competing microscopic effects, the thermal spin\naccumulation in germanium remains surprisingly almost unchanged under the\napplication of a gate voltage to the channel.",
        "positive": "Multiferroic kinks and spin-flop transition in Ni$_{2}$InSbO$_6$ from\n  first principles: Magnetoelectric multiferroics are key materials for next-generation devices\ndue to their entangled magnetic and ferroelectric properties. Spiral\nmultiferroics induce ferroelectric polarization and are particularly promising\nfor electric control of magnetism and magnetic control of ferroelectricity. In\nthis work, we uncover long-period incommensurate states characterized by unique\nmultiferroic kinks in corundum nickelate Ni$_{2}$InSbO$_6$. Utilizing a\n2-orbital $S=1$ model, we derive formulas for Heisenberg and anisotropic\nmagnetic exchanges and magnetically-induced polarization, enabling their\ncalculations from first principles. Our theory reproduces experimentally\nobserved magnetic structures and polarization dependence on the magnetic field\nand predicts a three-step magnetic phase transition (flat spiral $\\rightarrow$\nconical spiral $\\rightarrow$ spin-flop $\\rightarrow$ ferromagnet) under\nexternal magnetic fields. Kinks in the spiral phases repel each other through a\nYukawa-like potential arising from exchange of massive magnons. Furthermore,\nour continuum theory predicts that an electric field directed one way\nstabilizes the ferromagnetic state, while the opposite direction stabilizes the\nspiral layer state. Our findings open a new pathway to predictive\nfirst-principles modelling of multiferroics and may lead to technological\napplications based on multiferroic kinks."
    },
    {
        "anchor": "Point defects in the 1$T'$ and 2$H$ phases of single-layer MoS$_2$: A\n  comparative first-principles study: The metastable 1$T'$ phase of layered transition metal dichalcogenides has\nrecently attracted considerable interest due to electronic properties, possible\ntopological electronic phases and catalytic activity. We report a comprehensive\ntheoretical investigation of intrinsic point defects in the 1$T'$ crystalline\nphase of single-layer molybdenum disulfide (1$T'$-MoS$_2$), and provide\ncomparison to the well-studied semiconducting 2$H$ phase. Based on density\nfunctional theory calculations, we explore a large number of configurations of\nvacancy, adatom and antisite defects and analyse their atomic structure,\nthermodynamic stability, electronic and magnetic properties. The emerging\npicture suggests that, under thermodynamic equilibrium, 1$T'$-MoS$_2$ is more\nprone to hosting lattice imperfections than the 2$H$ phase. More specifically,\nour findings reveal that the S atoms that are closer to the Mo atomic plane are\nthe most reactive sites. Similarly to the 2$H$ phase, S vacancies and adatoms\nin 1$T'$-MoS$_2$ are very likely to occur while Mo adatoms and antisites induce\nlocal magnetic moments. Contrary to the 2$H$ phase, Mo vacancies in\n1$T'$-MoS$_2$ are expected to be an abundant defect due to the structural\nrelaxation that plays a major role in lowering the defect formation energy.\nOverall, our study predicts that the realization of high-quality flakes of\n1$T'$-MoS$_2$ should be carried out under very careful laboratory conditions\nbut at the same time the facile defects introduction can be exploited to tailor\nphysical and chemical properties of this polymorph.",
        "positive": "Disorder-induced significant enhancement in magnetization of ball-milled\n  Fe2CrGa alloy: A new disordered atom configuration in Fe2CrGa alloy has been created by\nball-milling method. This leads to a significant enhancement of the magnetic\nmoment up to 3.2~3.9 {\\mu}B and an increase of Curie temperature by about 200\nK, compared with the arc-melt samples. Combination of first-principles\ncalculations and experimental results reveals that Fe2CrGa alloy should\ncrystallize in Hg2CuTi based structure with different atomic disorders for the\nsamples prepared by different methods. It is addressed that magnetic\ninteractions play a crucial role for the system to adopt such an atomic\nconfiguration which disobeys the empirical rule."
    },
    {
        "anchor": "Kohn-Sham-Proca equations for ultrafast exciton dynamics: A long standing problem in time dependent density functional theory (TD-DFT)\nhas been the absence of a functional able to capture excitonic physics under\nlaser pump conditions. Here we introduce a Kohn-Sham-Proca scheme that we\ndemonstrate reproduces both linear response excitonic effects in the absorption\nin excellent agreement with experiment for a wide range of materials, but also\ncaptures excitonic physics in the highly non-linear regime of ultrafast laser\npumping, in particular laser fluence dependent \"bleaching\" (i.e. reduction) of\nthe excitonic weight and the appearance of excitonic side bands. The approach\nis a procedural functional -- the Kohn-Sham and Proca equations are\nsimultaneously time propagated -- allowing the straight-forward inclusion of,\nfor example, lattice and spin degrees of freedom into excitonic physics.",
        "positive": "Exotic single-photon and enhanced deep-level emissions in hBN strain\n  superlattice: The peculiar defect-related photon emission processes in 2D hexagonal boron\nnitride (hBN) have become a topic of intense research due to their potential\napplications in quantum information and sensing technologies. Recent efforts\nhave focused on activating and modulating the defect energy levels in hBN by\nmethods that can be integrated on a chip, and understanding the underlying\nphysical mechanism. Here, we report on exotic single photon and enhanced\ndeep-level emissions in 2D hBN strain superlattice, which is fabricated by\ntransferring multilayer hBN onto hexagonal close-packed silica spheres on\nsilica substrate. We realize effective activation of the single photon\nemissions (SPEs) in the multilayer hBN at the positions that are in contact\nwith the apex of the SiO2 spheres. At these points, the local tensile strain\ninduced blue-shift of the SPE is found to be up to 12 nm. Furthermore, high\nspatial resolution cathodoluminescence measurments show remarkable\nstrain-enhanced deep-level (DL) emissions in the multilayer hBN with the\nemission intensity distribution following the periodic hexagonal pattern of the\nstrain superlattice. The maximum DL emission enhancement is up to 350% with a\nenergy redshift of 6 nm. Our results provide a simple on-chip compatible method\nfor activating and tuning the defect-related photon emissions in multilayer\nhBN, demonstrating the potential of hBN strain superlattice as a building block\nfor future on-chip quantum nanophotonic devices."
    },
    {
        "anchor": "Thermoelastic relaxation in elastic structures with applications to thin\n  plates: A new result enables direct calculation of thermoelastic damping in vibrating\nelastic solids. The mechanism for energy loss is thermal diffusion caused by\ninhomogeneous deformation, flexure in thin plates. The general result is\ncombined with the Kirchhoff assumption to obtain a new equation for the\nflexural vibration of thin plates incorporating thermoelastic loss as a damping\nterm. The thermal relaxation loss is inhomogeneous and depends upon the local\nstate of vibrating flexure, specifically, the principal curvatures at a given\npoint on the plate. Thermal loss is zero at points where the principal\ncurvatures are equal and opposite, that is, saddle shaped or pure anticlastic\ndeformation. Conversely, loss is maximum at points where the curvatures are\nequal, that is, synclastic or spherical flexure. The influence of modal\nurvature on the thermoelastic damping is described through a modal\npparticipation factor. The effect of transverse thermal diffusion on plane wave\npropagation is also examined. It is shown that transverse diffusion effects are\nalways small provided the plate thickness is far greater than the thermal\nphonon mean free path, a requirement for the validity of the classical theory\nof heat transport. These results generalize Zener's theory of thermoelastic\nloss in beams and are useful in predicting mode widths in MEMS and NEMS\noscillators.",
        "positive": "Surface anchoring on liquid crystalline polymer brushes: We present a Monte Carlo study of the surface anchoring of a nematic fluid on\nswollen layers of grafted liquid crystalline chain molecules. The liquid\ncrystalline particles are modeled by soft repulsive ellipsoids, and the chains\nare made of the same particles. An appropriately modified version of the\nconfigurational bias Monte Carlo algorithm is introduced, which removes and\nredistributes chain bonds rather than whole monomers. With this algorithm, a\nwide range of grafting densities could be studied. The substrate is chosen such\nthat it favors a planar orientation (parallel to the surface). Depending on the\ngrafting density, we find three anchoring regimes: planar, tilted, and\nperpendicular alignment. At low grafting densities, the alignment is mainly\ndriven by the substrate. At high grafting densities, the substrate gradually\nloses its influence and the alignment is determined by the structure of the\ninterface between the brush and the pure solvent instead."
    },
    {
        "anchor": "Quantifying Mn diffusion through transferred versus directly-grown\n  graphene barriers: We quantify the mechanisms for manganese (Mn) diffusion through graphene in\nMn/graphene/Ge (001) and Mn/graphene/GaAs (001) heterostructures for samples\nprepared by graphene layer transfer versus graphene growth directly on the\nsemiconductor substrate. These heterostructures are important for applications\nin spintronics; however, challenges in synthesizing graphene directly on\ntechnologically important substrates such as GaAs necessitate layer transfer\nand anneal steps, which introduce defects into the graphene. \\textit{In-situ}\nphotoemission spectroscopy measurements reveal that Mn diffusion through\ngraphene grown directly on a Ge (001) substrate is 1000 times lower than Mn\ndiffusion into samples without graphene ($D_{gr,direct} \\sim\n4\\times10^{-18}$cm$^2$/s, $D_{no-gr} \\sim 5 \\times 10^{-15}$ cm$^2$/s at\n500$^\\circ$C). Transferred graphene on Ge suppresses the Mn in Ge diffusion by\na factor of 10 compared to no graphene ($D_{gr,transfer} \\sim\n4\\times10^{-16}cm^2/s$). For both transferred and directly-grown graphene, the\nlow activation energy ($E_a \\sim 0.1-0.5$ eV) suggests that Mn diffusion\nthrough graphene occurs primarily at graphene defects. This is further\nconfirmed as the diffusivity prefactor, $D_0$, scales with the defect density\nof the graphene sheet. Similar diffusion barrier performance is found on GaAs\nsubstrates; however, it is not currently possible to grow graphene directly on\nGaAs. Our results highlight the importance of developing graphene growth\ndirectly on functional substrates, to avoid the damage induced by layer\ntransfer and annealing.",
        "positive": "Proton Transfer in Phase IV of Solid Hydrogen and Deuterium: The recent discovery of phase IV of solid hydrogen and deuterium consisting\nof two alternate layers of graphenelike three-molecule rings and unbound H2\nmolecules have generated great interests. However, vibrational nature of phase\nIV remains poorly understood. Here, we report a peculiar proton transfer and a\nsimultaneous rotation of three molecule rings in graphenelike layers predicted\nby ab initio variable cell molecular dynamics simulations for phase IV of solid\nhydrogen and deuterium at pressure ranges of from 250 to 350 GPa and\ntemperature range of from 300 to 500 K. This proton transfer is intimately\nrelated to the particular elongation of molecules in graphenelike layers, and\nit becomes more pronounced with increasing pressure at the course of larger\nelongation of molecules. As the consequence of proton transfer, hydrogen\nmolecules in graphenelike layers are short lived and hydrogen vibration is\nstrongly anharmonic. Our findings provide direct explanations on the observed\nabrupt increase of Raman width at the formation of phase IV and its large\nincrease with pressure."
    },
    {
        "anchor": "Ab-initio theory of NMR chemical shifts in solids and liquids: We present a theory for the ab-initio computation of NMR chemical shifts\n(sigma) in condensed matter systems, using periodic boundary conditions. Our\napproach can be applied to periodic systems such as crystals, surfaces, or\npolymers and, with a super-cell technique, to non-periodic systems such as\namorphous materials, liquids, or solids with defects. We have computed the\nhydrogen sigma for a set of free molecules, for an ionic crystal, LiH, and for\na H-bonded crystal, HF, using density functional theory in the local density\napproximation. The results are in excellent agreement with experimental data.",
        "positive": "Diffusion and equilibration of site-preferences following transmutation\n  of tracer atoms: Using the method of perturbed angular correlation of gamma rays, diffusional\njump-frequencies of probe atoms can be measured through relaxation of the\nnuclear quadrupole interaction. This was first shown in 2004 for jumps of\ntracer atoms that lead to reorientation of the local electric field-gradient,\nsuch as jumps on the connected a-sublattice in the L12 crystal structure.\nStudies on many such phases using the 111In/Cd PAC probe are reviewed in this\npaper. A major finding from a 2009 study of indides of rare-earth elements,\nIn3R, was the apparent observation of two diffusional regimes: one dominant for\nheavy-lanthanide phases, R= Lu, Tm, Er, Dy, Tb, Gd, that was consistent with a\nsimple model of vacancy diffusion on the In a-sublattice, and another for\nlight-lanthanides, R= La, Ce, Pr, Nd, that had no obvious explanation but for\nwhich several alternative diffusion mechanisms were suggested. It is herein\nproposed that the latter regime arises not from a diffusion mechanism but from\ntransfer of Cd-probes from In-sites where they originate to R-sites as a\nconsequence of a change in site-preference of 111Cd-daughter atoms from\nIn-sites to R-sites following transmutation of 111In. Support for this transfer\nmechanism comes from a study of site-preferences and jump-frequencies of\n111In/Cd probes in Pd3R phases. Possible mechanisms for transfer are described,\nwith the most likely mechanism identified as one in which Cd-probes on a-sites\ntransfer to interstitial sites, diffuse interstitially, and then react with\nvacancies on b-sites. Implications of this proposal are discussed. For indides\nof heavy-lanthanide elements, the Cd-tracer remains on the In-sublattice and\nrelaxation gives the diffusional jump-frequency."
    },
    {
        "anchor": "First-principles study of the spin-lattice coulpling in spin frustrated\n  DyMn$_2$O$_5$: The lattice dynamic properties and spin-phonon coupling in DyMn$_2$O$_5$ are\nstudied by using the density-functional theory. The calculated phonon\nfrequencies are in very good agreement with experiments. We then compare the\nphonon modes calculated from different spin configurations. The results show\nthat the phonon frequencies change substantially in different spin\nconfigurations, suggesting that the spin-phonon coupling in this material is\nvery strong. Especially, the short range spin ordering has drastic effects on\nthe highest Raman and IR phonon modes that might be responsible for the\nobserved phonon anomalies near and above the magnetic phase transitions.",
        "positive": "An Artificially Lattice Mismatched Graphene/Metal Interface:\n  Graphene/Ni/Ir(111): We report the structural and electronic properties of an artificial\ngraphene/Ni(111) system obtained by the intercalation of a monoatomic layer of\nNi in graphene/Ir(111). Upon intercalation, Ni grows epitaxially on Ir(111),\nresulting in a lattice mismatched graphene/Ni system. By performing Scanning\nTunneling Microscopy (STM) measurements and Density Functional Theory (DFT)\ncalculations, we show that the intercalated Ni layer leads to a pronounced\nbuckling of the graphene film. At the same time an enhanced interaction is\nmeasured by Angle-Resolved Photo-Emission Spectroscopy (ARPES), showing a clear\ntransition from a nearly-undisturbed to a strongly-hybridized graphene\n$\\pi$-band. A comparison of the intercalation-like graphene system with flat\ngraphene on bulk Ni(111), and mildly corrugated graphene on Ir(111), allows to\ndisentangle the two key properties which lead to the observed increased\ninteraction, namely lattice matching and electronic interaction. Although the\nlatter determines the strength of the hybridization, we find an important\ninfluence of the local carbon configuration resulting from the lattice\nmismatch."
    },
    {
        "anchor": "Neutron Scattering Study of Relaxor Ferroelectric\n  (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3: Neutron elastic diffuse scattering experiments performed on Pb(Zn1/3Nb2/3)O3\n(PZN) and on its solid solution with PbTiO3(PT), known as PZN-xPT, with x=4.5%\nand 9% around many reflections show that diffuse scattering is observed around\nreflections with mixed indices in the transverse and diagonal directions only.\n  From the width of the diffuse scattering peak a correlation length is\nextracted. In PZN, we have reported that the diffuse scattering is more\nextended in the transverse than in the diagonal directions. In the present\nwork, the results show that the addition of PT leads to a broadening of the\ndiffuse scattering along the diagonal, relative to the transverse directions,\nindicating a change in the orientation of the polar regions. Also, with the\naddition of PT, the polar nanoregions condense at a higher temperature above\nthe transition than in pure PZN (> 40 K), due to stronger correlations between\nthe polar regions. Neutron inelastic scattering measurements have also been\nperformed on PZN-xPT. The results show the broadening of the transverse\nacoustic (TA) phonon mode at a small momentum transfer q upon cooling. We\nattribute this broadening to the appearance of the polar nanoregions.",
        "positive": "Bond Dipole Theory of Band Offset: Understanding the band offset between materials is pivotal for electronic\ndevice functionality. While traditional theories attribute this offset solely\nto intrinsic properties of constituent materials, interfacial chemistry\nintroduces complexities, including charge transfer dipoles. We address this\nchallenge by defining a reference system based on Wigner-Seitz atoms, which is\na charge partitioning that tessellates space while retaining bulk crystal\nsymmetry. The interfacial dipole is then expressed entirely by localized\ndipoles along interfacial bonds. Geometric analysis reveals that for isotropic\nmaterials, both bulk and interfacial contributions to the band offset are\norientation independent. This finding is confirmed through first-principles\ncalculations and analysis of 28 distinct interfaces, which show very little (<\n0.1 eV) dependence on orientation. Furthermore, the direction dependence of\nanisotropic materials is well captured by the theory. This work provides\ncrucial insights into the geometric underpinnings of band offset, offering a\ncomprehensive understanding essential for advancing materials design in\nelectronic applications."
    },
    {
        "anchor": "Dependence of the Atomic Level Green-Kubo Stress Correlation Function on\n  Wavevector and Frequency. Molecular Dynamics Results from a Model Liquid: We report on a further investigation of a new method that can be used to\naddress vibrational dynamics and propagation of stress waves in liquids. The\nmethod is based on the decomposition of the macroscopic Green-Kubo stress\ncorrelation function into the atomic level stress correlation functions. This\ndecomposition, as was demonstrated previously for a model liquid studied in\nmolecular dynamics simulations, reveals the presence of stress waves\npropagating over large distances and a structure that resembles the pair\ndensity function. In this paper, by performing the Fourier transforms of the\natomic level stress correlation functions, we elucidate how the lifetimes of\nthe stress waves and the ranges of their propagation depend on their frequency,\nwavevector, and temperature. These results relate frequency and wavevector\ndependence of the generalized viscosity to the character of propagation of the\nshear stress waves. In particular, the results suggest that an increase in the\nvalue of the frequency dependent viscosity at low frequencies with decrease of\ntemperature is related to the increase in the ranges of propagation of the\nstress waves of the corresponding low frequencies. We found that the ranges of\npropagation of the shear stress waves of frequencies less than half of the\nEinstein frequency, extend well beyond the nearest neighbor shell even above\nthe melting temperature. The results also show that the crossover from\nquasilocalized to propagating behavior occurs at frequencies usually associated\nwith the Boson peak.",
        "positive": "Ferromagnetic resonance force microscopy on microscopic cobalt single\n  layer films: We report mechanical detection of ferromagnetic resonance signals from\nmicroscopic Co single layer thin films using a magnetic resonance force\nmicroscope (MRFM). Variations in the magnetic anisotropy field and the\ninhomogeneity of were clearly observed in the FMR spectra of microscopic Co\nthin films 500 and 1000 angstrom thick and 40 X 200 micron^2 in lateral extent.\nThis demonstrates the important potential that MRFM detection of FMR holds for\nmicroscopic characterization of spatial distribution of magnetic properties in\nmagnetic layered materials and devices."
    },
    {
        "anchor": "Observation of zigzag and armchair edges of graphite using scanning\n  tunneling microscopy and spectroscopy: The presence of structure-dependent edge states of graphite is revealed by\nboth ambient- and ultra-highvacuum- (UHV) scanning tunneling microscopy (STM) /\nscanning tunneling spectroscopy (STS) observations. On a hydrogenated zigzag\n(armchair) edge, bright spots are (are not) observed together with (SQRT(3) by\nSQRT(3))R30 superlattice near the Fermi level (V_S = &#8722;30 mV for a peak of\nthe local density of states (LDOS)) under UHV, demonstrating that a zigzag edge\nis responsible for the edge states, although there is no appreciable difference\nbetween as-prepared zigzag and armchair edges in air. Even in hydrogenated\narmchair edge, however, bright spots are observed at defect points, at which\npartial zigzag edges are created in the armchair edge.",
        "positive": "Random sequential adsorption of unoriented cuboids with a square base\n  and a comparison of cuboid-cuboid intersection tests: In the paper, packings built of identical cuboids with a square base created\nby random sequential adsorption are studied. The result of the study show that\nthe packing of the highest density are obtained for oblate and prolate cuboids\nof the edge-edge length ratios of $0.7$ and $1.4$. For both cases, the packing\nfraction is $0.400 \\pm 0.002$, which is approximately 8% higher than the value\nreported for cubes. Additionally, because the crucial part of the packing\ngeneration algorithm is the cuboid-cuboid intersection detection, several\nmethods were tested. It appears that the fastest one is based on the separating\naxis theorem."
    },
    {
        "anchor": "Density functional theory calculations on magnetic properties of\n  actinide compounds: We have performed a detailed analysis of the magnetic (collinear and\nnoncollinear) order and atomic and the electron structures of UO2, PuO2 and UN\non the basis of density functional theory with the Hubbard electron correlation\ncorrection (DFT+U). We have shown that the 3-k magnetic structure of UO2 is the\nlowest in energy for the Hubbard parameter value of U=4.6 eV (and J=0.5 eV)\nconsistent with experiments when Dudarev's formalism is used. In contrast to\nUO2, UN and PuO2 show no trend for a distortion towards rhombohedral structure\nand, thus, no complex 3-k magnetic structure is to be anticipated in these\nmaterials.",
        "positive": "Stone-Wales graphene: A Two Dimensional Carbon Semi-Metal with Magic\n  Stability: A two-dimensional carbon allotrope, Stone-Wales graphene, is identified in\nstochastic group and graph constrained searches and systematically investigated\nby first-principles calculations. Stone-Wales graphene consists of\nwell-arranged Stone-Wales defects, and it can be constructed through a\n90$^\\circ$ bond-rotation in a $\\sqrt{8}$$\\times$$\\sqrt{8}$ super-cell of\ngraphene. Its calculated energy relative to graphene, +149 meV/atom, makes it\nmore stable than the most competitive previously suggested graphene allotropes.\nWe find that Stone-Wales graphene based on a $\\sqrt{8}$ super-cell is more\nstable than those based on $\\sqrt{9} \\times \\sqrt{9}$, $\\sqrt{12} \\times\n\\sqrt{12}$ and $\\sqrt{13} \\times \\sqrt{13}$ super-cells, and is a \"magic size\"\nthat can be further understood through a simple \"energy splitting and\ninversion\" model. The calculated vibrational properties and molecular dynamics\nof SW-graphene confirm that it is dynamically stable. The electronic structure\nshows SW-graphene is a semimetal with distorted, strongly anisotropic Dirac\ncones."
    },
    {
        "anchor": "Isotropic finite-difference approximations for phase-field simulations\n  of polycrystalline alloy solidification: Phase-field models of microstructural pattern formation during alloy\nsolidification are commonly solved numerically using the finite-difference\nmethod, which is ideally suited to carry out computationally efficient\nsimulations on massively parallel computer architectures such as Graphic\nProcessing Units. However, one known drawback of this method is that the\ndiscretization of differential terms involving spatial derivatives introduces a\nspurious lattice anisotropy that can influence the solid-liquid interface\ndynamics. We find that this influence is significant for the case of\npolycrystalline dendritic solidification, where the crystal axes of different\ngrains do not generally coincide with the reference axes of the\nfinite-difference lattice. In particular, we find that with the commonly used\nfinite-difference implementation of the quantitative phase-field model of\nbinary alloy solidification, both the operating state of the dendrite tip and\nthe dendrite growth orientation are strongly affected by the lattice\nanisotropy. To circumvent this problem, we use known methods in both real and\nFourier space to derive finite-difference approximations of leading\ndifferential terms in 2D and 3D that are isotropic at order $h^2$ of the\nlattice spacing $h$. Importantly, those terms include the divergence of the\nanti-trapping current that is found to have a critical influence on pattern\nselection. The 2D and 3D discretizations use an approximated form of the\nanti-trapping current that facilitates the Fourier-space derivation of the\nassociated isotropic differential operator at $O(h^2)$, but we also derive a 2D\ndiscretization of the standard form of this current. Finally, we present 2D and\n3D phase-field simulations of alloy solidification, showing that the isotropic\nfinite-difference implementations can dramatically reduce spurious lattice\nanisotropy effects.",
        "positive": "Accelerated dynamics with the dynamical activation-relaxation technique: The dynamics of many atomic systems is controlled by activated events taking\nplace on a time scale which is long compared to that associated with thermal\nvibrations. This often places problems of interest outside the range of\nstandard simulation methods such as molecular dynamics. We present here an\nalgorithm, the dynamical activation-relaxation technique (DART), which slows\ndown thermal vibrations, while leaving untouched the activated processes which\nconstitute the long-time dynamics. As an example, we show that it is possible\nto accelerate considerably the dynamics of self-defects in a 1000-atom cell of\nc-Si over a wide range of temperatures."
    },
    {
        "anchor": "Multilayer silicene: structure, electronics, and mechanical property: Herein, we performed first principle calculation and classical molecular\ndynamics simulation to study structural optimization, band structure, and\nmechanical properties of differently stacked multilayer silicene. Several local\nenergy minima have been identified as metastable conformation with different\nstacking mode and layer number. Bandstructure of low buckled AA bilayer\nsilicene optimized with SCAN+rvv10 presents semiconducting behavior with a\nbandgap of 0.4419ev. Young's modulus of multilayer silicene shows low\ndependency on layer number or stacking mode. Whereas, fracture stress and\nstrain is sensitive to the number of layers, specific stacking mode, and\nchirality. Furthermore, bending modulus of multilayer silicene (e.g., 0.44ev\nfor monolayer silicene) is even lower than that of graphene, which may\nattribute to the flexibility of bond angle.",
        "positive": "Emergent magnetic states due to stacking and strain in the van der Waals\n  magnetic trilayer CrI3: Recently, three different magnetic states were observed experimentally in\ntrilayer CrI3 under pressure,including ferromagnetic (FM)-upupup, FM-downupdown\nand FM-upupdown. To reveal the nature of the observed three magnetic states, we\nstudied the magnetic properties of four possible stacking structures in\ntrilayer CrI3: I (rhombohedral), II (monoclinic), III (hexagonal) and IV\n(triclinic). We find that all four stacking structures possess the FM-upupup\nground state. After applying a few strains, the FM-downupdown becomes the\nground state in II and III structures, and the FM-upupdown is preferred in IV\nstructure, while the FM-upupup persists in I structure. Our results unveil that\nthe three magnetic states observed in trilayer CrI3 may correspond to different\nstacking structures with small tensile strains, which can well interpret the\nexperimentally obtained pressure dependent interlayer coupling and Curie\ntemperature. Our present study paves a way to design the magnetic multilayers\nwith required magnetic states by tuning stacking and strain."
    },
    {
        "anchor": "Magnetic response and electronic states of well defined\n  Graphene/Fe/Ir(111) heterostructure: We investigate a well defined heterostructure constituted by magnetic Fe\nlayers sandwiched between graphene (Gr) and Ir(111). The challenging task to\navoid Fe-C solubility and Fe-Ir intermixing has been achieved with atomic\ncontrolled Fe intercalation at moderate temperature below 500 K. Upon\nintercalation of a single ordered Fe layer in registry with the Ir substrate,\nan intermixing of the Gr bands and Fe d states breaks the symmetry of the Dirac\ncone, with a downshift in energy of the apex by about 3 eV, and well-localized\nFe intermixed states induced in the energy region just below the Fermi level.\nFirst principles electronic structure calculations show a large spin splitting\nof the Fe states, resulting in a majority spin channel almost fully occupied\nand strongly hybridized with Gr {\\pi} states. X-ray magnetic circular dichroism\non the Gr/Fe/Ir heterostructure reveals an ordered spin configuration with a\nferromagnetic response of Fe layer(s), with enhanced spin and orbital\nconfigurations with respect to the bcc-Fe bulk values. The magnetization\nswitches from a perpendicular easy magnetization axis when the Fe single layer\nis lattice matched with the Ir(111) surface to a parallel one when the Fe thin\nfilm is almost commensurate with graphene.",
        "positive": "On the analysis of stage I in the resistivity recovery of electron\n  irradiated iron: The experimental results of Takaki et al. [1] on the stage I resistivity\nrecovery of electron irradiated iron are analyzed using the analytical theory\nof diffusion annealing formulated by Simpson & Sossin [2] and Schroeder [3]\ntaking into account the recent first-principles calculations of Fu et al. [4]\nregarding the mobility of interstitials. Excellent agreement between theory and\nexperiment is obtained by a minimal set of adjustable parameters. The results\nshow that the diffusion annealing equations can be successfully employed for\nthe analysis of recovery experiments in iron."
    },
    {
        "anchor": "Insights into $\\text{Li}^{+}$, $\\text{Na}^{+}$ and $\\text{K}^{+}$\n  Intercalation in Lepidocrocite-type Layered $\\text{TiO}_{2}$ Structures: A lamellar lepidocrocite-type titanate structure with ~25%\n$\\text{Ti}^{4+}$vacancies was recently synthesized, and it showed potential for\nuse as an electrode in rechargeable lithium-ion batteries. In addition to\nlithium, we explore this material's ability to accommodate other monovalent\nions with greater natural abundance (e.g. sodium and potassium) in order to\ndevelop lower-cost alternatives to lithium-ion batteries constructed from more\nwidely available elements. Galvanostatic discharge/charge curves for the\nlepidocrocite material indicate that increasing the ionic radius of the\nmonovalent ion results in a deteriorating performance of the electrode. Using\nfirst-principles electronic structure calculations, we identify the relaxed\ngeometries of the structure for various positions of the ion in the structure.\nWe then use these geometries to compute the energy of formations. Additionally,\nwe determine that all ions are favorable in the structure, but interlayer\npositions are preferred compared to vacancy positions. We also conclude that\nthe exchange between the interlayer and vacancy positions is a process which\ninvolves the interaction between interlayer water and surface hydroxyl groups\nnext to the titanate layer. We observe a cooperative effect between structural\nwater and $\\text{OH}$ groups to assist alkali-ions to move from the interlayer\nto the vacancy site. Thus, the as-synthesized lepidocrocite serves as a\nprototypical structure to investigate both the migration mechanism of ions\nwithin a confined space along with the interaction between water molecules and\nthe titanate framework.",
        "positive": "Relativistic magnetic interactions from non-orthogonal basis sets: We propose a method to determine the magnetic exchange interaction and\non-site anisotropy tensors of extended Heisenberg spin models from density\nfunctional theory including relativistic effects. The method is based on the\nLiechtenstein-Katsnelson-Antropov-Gubanov torque formalism, whereby energy\nvariations upon infinitesimal rotations are performed. We assume that the\nKohn-Sham Hamiltonian is expanded in a non-orthogonal basis set of\npseudo-atomic orbitals. We define local operators that are both hermitian and\nsatisfy relevant sum rules. We demonstrate that in the presence of spin-orbit\ncoupling a correct mapping from the density functional total energy to a spin\nmodel that relies on the rotation of the exchange field part of the Hamiltonian\ncan not be accounted for by transforming the full Hamiltonian. We derive a set\nof sum rules that pose stringent validity tests on any specific calculation. We\nshowcase the flexibility and accuracy of the method by computing the exchange\nand anisotropy tensors of both well-studied magnetic nanostructures and of\nrecently synthesized two-dimensional magnets. Specifically, we benchmark our\napproach against the established Korringa-Kohn-Rostoker Green's function method\nand show that they agree well. Finally, we demonstrate how the application of\nbiaxial strain on the two-dimensional magnet T-CrTe2 can trigger a magnetic\nphase transition."
    },
    {
        "anchor": "The Wannier-Functions Software Ecosystem for Materials Simulations: Over the last two decades, following the early developments on\nmaximally-localized Wannier functions, an ecosystem of electronic-structure\nsimulation techniques and software leveraging the Wannier representation has\nflourished. This environment includes codes to obtain Wannier functions and\ninterfaces with first-principles simulation software, as well as an increasing\nnumber of related post-processing packages. Wannier functions can be obtained\nfor isolated or extended systems (both crystalline and disordered), and can be\nused to understand chemical bonding, to characterize polarization,\nmagnetization, and topology, or as an optimal basis set, providing very\naccurate interpolations in reciprocal space or large-scale Hamiltonians in real\nspace. In this review, we summarize the current landscape of techniques,\nmaterials properties and simulation codes based on Wannier functions that have\nbeen made accessible to the research community, and that are now well\nintegrated into what we term a \\emph{Wannier-functions software ecosystem}.\nFirst we introduce the theory and practicalities of Wannier functions, starting\nfrom their broad domains of applicability to advanced minimization methods\nusing alternative approaches beyond maximal localization. Then we define the\nconcept of a Wannier ecosystem and its interactions and interoperability with\nmany quantum engines and post-processing packages. We focus on some of the key\nproperties that are empowered by such ecosystem\\textemdash from band\ninterpolations and large-scale simulations to electronic transport, Berryology,\ntopology, electron-phonon couplings, dynamical mean-field theory, embedding,\nand Koopmans functionals\\textemdash concluding with the current status of\ninteroperability and automation. The review aims at highlighting basic theory\nand concepts behind codes, providing relevant pointers to more in-depth\nreferences.",
        "positive": "Pressure-enhanced ferromagnetism in layered CrSiTe3 flakes: The research on van der Waals (vdW) layered ferromagnets have promoted the\ndevelopment of nanoscale spintronics and applications. However, low-temperature\nferromagnetic properties of these materials greatly hinder their applications.\nHere, we report pressure-enhanced ferromagnetic behaviours in layered CrSiTe3\nflakes revealed by high-pressure magnetic circular dichroism (MCD) measurement.\nAt ambient pressure, CrSiTe3 undergoes a paramagnetic-to-ferromagnetic phase\ntransition at 32.8 K, with a negligible hysteresis loop, indicating a soft\nferromagnetic behaviour. Under 4.6 GPa pressure, the soft ferromagnet changes\ninto hard one, signalled by a rectangular hysteretic loop with remnant\nmagnetization at zero field. Interestingly, with further increasing pressure,\nthe coercive field (H_c) dramatically increases from 0.02 T at 4.6 GPa to 0.17\nT at 7.8 GPa, and the Curie temperature (T_c^h: the temperature for closing the\nhysteresis loop) also increases from ~36 K at 4.6 GPa to ~138 K at 7.8 GPa. The\ninfluences of pressure on exchange interactions are further investigated by\ndensity functional theory calculations, which reveal that the in-plane\nnearest-neighbor exchange interaction and magneto-crystalline anisotropy\nincrease simultaneously as pressure increases, leading to increased H_c and\nT_c^h in experiments. The effective interaction between magnetic couplings and\nexternal pressure offers new opportunities for both searching room-temperature\nlayered ferromagnets and designing pressure-sensitive magnetic functional\ndevices."
    },
    {
        "anchor": "Electronic Structure of Magnetic Semiconductor CdCr_2Te_4: A Possible\n  Spin-Dependent Symmetry Filter: We present a theoretical investigation of the electronic and magnetic\nstructure of spinel CdCr_2Te_4 using density functional theory, its extensions\nvia onsite Hubbard U interactions, and a screened-hybrid-functional exchange\npotential. We find that the ground state is semiconducting within the latter\napproach, and within this magnetic-semiconducting system we compute the complex\nband structure, finding a slowly decaying evanescent $\\tilde{\\Delta}_1$ state\npossibly suitable for realizing a spin-dependent symmetry filter effect.",
        "positive": "Striped electronic phases in an incommensurately modulated van der Waals\n  superlattice: Electronic properties of crystals can be manipulated using spatially periodic\nmodulations. Long-wavelength, incommensurate modulations are of particular\ninterest, exemplified recently by moir\\'e patterned van der Waals (vdW)\nheterostructures. Bulk vdW superlattices hosting interfaces between clean 2D\nlayers represent scalable bulk analogs of vdW heterostructures and present a\ncomplementary venue to explore incommensurately modulated 2D states. Here we\nreport the bulk vdW superlattice SrTa$_2$S$_5$ realizing an incommensurate 1D\nmodulation of 2D transition metal dichalcogenide (TMD) $H$-TaS$_2$ layers.\nHigh-quality electronic transport in the $H$-TaS$_2$ layers, evidenced by\nquantum oscillations, is made anisotropic by the modulation and shows\ncommensurability oscillations akin to lithographically modulated 2D systems. We\nalso find unconventional, clean-limit superconductivity (SC) in SrTa$_2$S$_5$\nwith a pronounced suppression of interlayer coherence relative to intralayer\ncoherence. Such a hierarchy can arise from pair-density wave (PDW) SC with\nmismatched spatial arrangement in adjacent superconducting layers. Examining\nthe in-plane magnetic field $H_{ab}$ dependence of interlayer critical current\ndensity $J_c$, we find anisotropy with respect to $H_{ab}$ orientation: $J_c$\nis maximized (minimized) when $H_{ab}$ is perpendicular (parallel) to the\nstripes, consistent with 1D PDW SC. From diffraction we find the structural\nmodulation is shifted between adjacent $H$-TaS$_2$ layers, suggesting\nmismatched 1D PDW is seeded by the striped structure. With a high-mobility\nFermi liquid in a coherently modulated structure, SrTa$_2$S$_5$ is a promising\nhost for novel phenomena anticipated in clean, striped metals and\nsuperconductors. More broadly, SrTa$_2$S$_5$ establishes bulk vdW superlattices\nas macroscopic platforms to address long-standing predictions for modulated\nelectronic phases."
    },
    {
        "anchor": "Current-Induced Magnetization Switching in Permalloy-based Nanopillars\n  with Cu, Ag, and Au: We compare magnetoresistances (MR) and switching currents (I_s) at room\ntemperature (295K) and 4.2K for Permalloy/N/Permalloy nanopillars undergoing\ncurrent-induced magnetization switching (CIMS), with non-magnetic metals N =\nCu, Ag, and Au. The N-metal thickness is held fixed at 10 nm. Any systematic\ndifferences in MR and I_s for the different N-metals are modest, suggesting\nthat Ag and Au represent potentially viable alternatives for CIMS studies and\ndevices to the more widely used Cu.",
        "positive": "Silicon-doped $\u03b2$-Ga$_2$O$_3$ films grown at 1 $\u03bc$m/h by suboxide\n  molecular-beam epitaxy: We report the use of suboxide molecular-beam epitaxy (S-MBE) to grow\n$\\beta$-Ga$_2$O$_3$ at a growth rate of ~1 ${\\mu}$m/h with control of the\nsilicon doping concentration from 5x10$^{16}$ to 10$^{19}$ cm$^{-3}$. In S-MBE,\npre-oxidized gallium in the form of a molecular beam that is 99.98\\% Ga$_2$O,\ni.e., gallium suboxide, is supplied. Directly supplying Ga2O to the growth\nsurface bypasses the rate-limiting first step of the two-step reaction\nmechanism involved in the growth of $\\beta$-Ga$_2$O$_3$ by conventional MBE. As\na result, a growth rate of ~1 ${\\mu}$m/h is readily achieved at a relatively\nlow growth temperature (T$_{sub}$ = 525 $^\\circ$C), resulting in films with\nhigh structural perfection and smooth surfaces (rms roughness of < 2 nm on ~1\n${\\mu}$m thick films). Silicon-containing oxide sources (SiO and SiO$_2$)\nproducing an SiO suboxide molecular beam are used to dope the\n$\\beta$-Ga$_2$O$_3$ layers. Temperature-dependent Hall effect measurements on a\n1 ${\\mu}$m thick film with a mobile carrier concentration of 2.7x10$^{17}$\ncm$^{-3}$ reveal a room-temperature mobility of 124 cm$^2$ V$^{-1}$ s$^{-1}$\nthat increases to 627 cm$^2$ V$^{-1}$ s$^{-1}$ at 76 K; the silicon dopants are\nfound to exhibit an activation energy of 27 meV. We also demonstrate working\nMESFETs made from these silicon-doped $\\beta$-Ga$_2$O$_3$ films grown by S-MBE\nat growth rates of ~1 ${\\mu}$m/h."
    },
    {
        "anchor": "A new mean field approach to finite spin systems: It is shown that a spin system is equivalent to a set of constrained harmonic\noscillators. For finite, but large, systems, a continuous approximation to the\ndensity of states can be used, and the oscillator frequencies can be exactly\ncomputed. In the phase transition, the effective frequency of the lowest mode\npasses through zero, that is, it becomes an inverted oscillator. In the small\noscillations regime, the oscillators can be treated as independent and the\nthermodynamic magnitudes can be computed. We show explicit calculations in a\ndisordered, frustrated, high coordination number Blume Capel model with 60,000\nspins.",
        "positive": "Luminescence of alpha-quartz: Among the host materials luminescence the luminescence of the self-trapped\nexciton (STE) is reviewed. This luminescence, which band is situated at 2.6 to\n2.7 eV, could be observed mainly under ionising radiation with energetic yield\nabout 0.2. The STE does not participate in pure recombination processes. Host\nmaterial defect luminescence at 5 eV appears in alpha-quartz after heavy\nirradiation. It is constituted of permanent defect after neutron irradiation\nand transient defect after dens electron beam irradiation. This luminescence\ncould be observed well at temperatures below 60 K. All another luminescence are\nof impurity nature. The Ge impurity luminescence in alpha-quartz explained as\nSTE near Ge. The aluminium and alkali complexes. One of them is with UV band at\n6 eV, appears at low temperatures and could be excited only in tunnelling\nrecombination process between pairs (AlO4 Me), where Me is an alkali ion\ncaptured an electron and a hole remains on aluminium tetrahedron. Another\nluminescence with band at 3.4 eV is also luminescence of complexes (AlO4 Me),\nwhich behaviour is similar to the luminescence of alkali alumosilicate glass.\nThe third luminescence with band at 3 eV could be observed mainly in natural\nalpha-quartz, bright at temperatures below 200 K and is interpreted as STE like\nluminescence at alumosilicate clasters. The exchange of alkali ions to noble\nions of copper of silver reduces original luminescence of alumo alkali\ncomplexes and luminescence of noble ions appears. The main band of copper\nrelated luminescence is at 3.4 eV and that of silver is at 4.75 eV, both could\nbe observed up to 500 K. their nature could be well described in terms of\nintraions transition. Exchange of noble ions back to alkali ions renews initial\nluminescence of the samples."
    },
    {
        "anchor": "Evaluating transition-metal oxides within DFT-SCAN and SCAN+U frameworks\n  for solar thermochemical applications: Using the strongly constrained and appropriately normed (SCAN) and SCAN+U\napproximations for describing electron exchange-correlation (XC) within density\nfunctional theory, we investigate the oxidation energetics, lattice constants,\nand electronic structure of binary Ce-, Mn-, and Fe-oxides, which are crucial\ningredients for generating renewable fuels using two-step, oxide-based, solar\nthermochemical reactors. Unlike other common XC functionals, we find that SCAN\ndoes not over-bind the O2 molecule, based on direct calculations of its bond\nenergy and robust agreement between calculated formation enthalpies of main\ngroup oxides versus experiments. However, in the case of transition-metal\noxides (TMOs), SCAN systematically overestimates (i.e., yields too negative)\noxidation enthalpies due to remaining self-interaction errors in the\ndescription of their ground-state electronic structure. Adding a Hubbard U term\nto the transition-metal centers, where the magnitude of U is determined from\nexperimental oxidation enthalpies, significantly improves the qualitative\nagreement and marginally improves the quantitative agreement of\nSCAN+U-calculated electronic structure and lattice parameters, respectively,\nwith experiments. Importantly, SCAN predicts the wrong ground-state structure\nfor a few oxides, namely, Ce2O3, Mn2O3, and Fe3O4, while SCAN+U predicts the\nright polymorph for all systems considered in this work. Hence, the SCAN+U\nframework, with an appropriately determined U, will be required to accurately\ndescribe ground-state properties and yield qualitatively consistent electronic\nproperties for most transition- metal and rare earth oxides.",
        "positive": "A New Class of Alumina-Forming Superalloy for 3D Printing: A new class of crack-resistant nickel-based superalloy containing high\n$\\gamma^\\prime$ fraction is studied for the laser-powder bed fusion (L-PBF)\nprocess. The effects of the (Nb+Ta)/Al ratio is emphasised, a strategy that is\nshown to confer excellent low-temperature strength whilst maintaining oxidation\nresistance at high temperatures via stable alumina scale formation. The\nprocessability of the new alloys is characterised with respect to defect\nassessment by micro-focus x-ray computed tomography; use is made of a prototype\nturbine blade geometry and the heritage alloy CM247LC as a benchmark. In all\ncases, some processing-related porosity is present in thin wall sections such\nas the trailing edge, but this can be avoided by judicious processing. The\ncracking seen in CM247LC -- in solid-state, liquation and solidification forms\n-- is avoided. A novel sub-solvus heat treatment strategy is proposed which\ntakes advantage of AM not requiring solutioning; super-solvus heat treatment is\ninappropriate since it embrittles the material by deterioration of the texture\nand coarsening of grain boundary carbides. The tensile strength of the new\nsuperalloy is greatest when the Nb+Ta content is highest and exceeds that of\nCM247LC up to $\\sim$900$\\,$$^\\circ$C. The oxidation resistance is best when Al\ncontent is highest, and oxidation-assisted cracking resistance maximized when\nthe (Nb+Ta)/Al ratio is balanced. In all cases these are equivalent or superior\nto that of CM247LC. Nevertheless, the creep resistance of the new alloys is\nsomewhat inferior to that of CM247LC for which the $\\gamma^\\prime$, C, and B\ncontents are higher; this implies a processing/property trade-off which\nrequires further clarification."
    },
    {
        "anchor": "Exploring the role of electronic structure on photo-catalytic behavior\n  of carbon-nitride polymorphs: A fully self-consistent density-functional theory (DFT) with improved\nfunctionals is used to provide a comprehensive account of structural,\nelectronic, and optical properties of C$_{3}$N$_{4}$ polymorphs. Using our\nrecently developed van Leeuwen-Baerends (vLB) corrected local-density\napproximation (LDA), we implemented LDA+vLB within full-potential\nN$^{th}$-order muffin-tin orbital (FP-NMTO) method and show that it improves\nstructural properties and band gaps compared to semi-local functionals\n(LDA/GGA). We demonstrate that the LDA+vLB predicts band-structure and\nwork-function for well-studied 2D-graphene and bulk-Si in very good agreement\nwith experiments, and more exact hybrid functional (HSE) calculations as\nimplemented in the Quantum-Espresso (QE) package. The structural and\nelectronic-structure (band gap) properties of C$_{3}$N$_{4}$ polymorphs\ncalculated using FP-NMTO-LDA+vLB is compared with more sophisticated\nhybrid-functional calculations. We also perform detailed investigation of\nphotocatalytic behavior using QE-HSE method of C$_{3}$N$_{4}$ polymorphs\nthrough work-function, band (valence and conduction) position with respect to\nwater reduction and oxidation potential. Our results show\n$\\gamma$-C$_{3}$N$_{4}$ as the best candidate for photocatalysis among all the\nC$_{3}$N$_{4}$~polymorphs but it is dynamically unstable at `zero' pressure. We\nshow that $\\gamma$-C$_{3}$N$_{4}$ can be stabilized under hydrostatic-pressure,\nwhich improves its photocatalytic behavior relative to water reduction and\noxidation potentials.",
        "positive": "Nano tracks in fullerene film by dense electronic excitations: In the present work, we investigate the formation of nano tracks by cluster\nand mono-atomic ion beams in the fullerene (C60) thin films by High Resolution\nTransmission Electron Microscopy (HRTEM). The fullerene films on carbon coated\ngrids were irradiated by 30 MeV C60 cluster beam and 120 MeV Au mono-atomic\nbeams at normal and grazing angle to the incident ion beams. The studies show\nthat the cluster beam creates latent tracks of an average diameter of around 20\nnm. The formation of large size nano tracks by cluster beam is attributed to\nthe deposition of large electronic energy density as compared to mono-atomic\nbeams."
    },
    {
        "anchor": "Roles of adiabatic and nonadiabatic spin transfer torques on magnetic\n  domain wall motion: Electric current exerts torques-so-called spin transfer torques (STTs)-on\nmagnetic domain walls (DWs), resulting in DW motion. At low current densities,\nthe STTs should compete against disorders in ferromagnetic nanowires but the\nnature of the competition remains poorly understood. By achieving\ntwo-dimensional contour maps of DW speed with respect to current density and\nmagnetic field, here we visualize unambiguously distinct roles of the two\nSTTs-adiabatic and nonadiabatic-in scaling behaviour of DW dynamics arising\nfrom the competition. The contour maps are in excellent agreement with\npredictions of a generalized scaling theory, and all experimental data collapse\nonto a single curve. This result indicates that the adiabatic STT becomes\ndominant for large current densities, whereas the nonadiabatic STT-playing the\nsame role as a magnetic field-subsists at low current densities required to\nmake emerging magnetic nanodevices practical.",
        "positive": "Coupling of the Local Defect and Magnetic Structure of Wustite, Fe1-xO: The local nuclear and magnetic structure of wustite, Fe1-xO, and the coupling\nbetween them, has been examined using reverse Monte Carlo refinements of\nvariable-temperature neutron total scattering data. The results from this\nanalysis suggest that the individual units in a tetrahedral defect cluster are\nconnected along <110> vectors into a Koch-Cohen-like arrangement, with the\nmajority of octahedral vacancies concentrated near these defects. Bond valence\ncalculations indicate a change in the charge distribution on the cations with\nthe charge on the tetrahedral interstitials increasing on cooling. The magnetic\nstructure is more complex than previously thought, corresponding to a\nnon-collinear spin arrangement described by a superposition of a condensed spin\nwave on the established type-II antiferromagnetic ordering. This leads to an\narchitecture with four groups of cations each with different spin directions.\nThe cations within the interstitial clusters appear to be weakly\nferromagnetically coupled and their spins are correlated to the spins of the\noctahedral cations closest to them. This work not only provides further insight\ninto the local structure of wustite but also a better understanding of the\ncoupling between defect structures and magnetic and charge-ordering in complex\nmaterials."
    },
    {
        "anchor": "Mechanical properties and thermal conductivity of graphitic carbon\n  nitride: A molecular dynamics study: Graphitic carbon nitride nanosheets are among 2D attractive materials due to\npresenting unusual physicochemical properties.Nevertheless, no adequate\ninformation exists about their mechanical and thermal properties. Therefore, we\nused classical molecular dynamics simulations to explore the thermal\nconductivity and mechanical response of two main structures of single-layer\ntriazine-basedg-C3N4 films.By performing uniaxial tensile modeling, we found\nremarkable elastic modulus of 320 and 210 GPa, and tensile strength of 47 GPa\nand 30 GPa for two different structures of g-C3N4sheets. Using equilibrium\nmolecular dynamics simulations, the thermal conductivity of free-standing\ng-C3N4 structures were also predicted to be around 7.6 W/mK and 3.5 W/mK. Our\nstudy suggests the g-C3N4films as exciting candidate for reinforcement of\npolymeric materials mechanical properties.",
        "positive": "Crystal chemistry and ab initio prediction of ultra-hard rhombohedral\n  B2N2 and BC2N: New ultra-hard rhombohedral B2N2 and BC2N - or hexagonal B6N6 and B3C6N3 -\nare derived from 3R graphite based on crystal chemistry rationale schematizing\na mechanism for 2D => 3D transformation. Full unconstrained geometry\noptimizations leading to ground state energy structures and energy derived\nquantities as energy-volume equation of states (EOS) were based on computations\nwithin the density functional theory (DFT) with generalized gradient\napproximation (GGA) for exchange-correlation (XC) effects. The new binary and\nternary phases are characterized by tetrahedral stacking alike diamond,\nvisualized with charge density representations, and illustrating ion\ncharacters. Atom averaged total energies are similar between cubic BN and\nrh-B2N2 on one hand, and larger stabilization of rhombohedral BC2N versus cubic\nand orthorhombic forms (in literature assessed from favored C-C and B-N\nbonding), on the other hand. The electronic band structures are characteristic\nof insulators with Egap ~ 5 eV. Both phases are characterized by large bulk and\nshear moduli and very high hardness values i.e. HV(rh-B2N2) = 74 GPa and\nHV(rh-BC2N) = 87 GPa."
    },
    {
        "anchor": "Ferroelectric Polarization in Antiferroelectric Chalcogenide Perovskite\n  BaZrS3 Thin Film: Bulk chalcogenide perovskite BaZrS3 (BZS), with a direct band gap in visible\nregion, is an important photovoltaic material, albeit with limited\napplicability owing to its antiferroelectric (AF) nature. Presently,\nferroelectric (FE) perovskite-based photovoltaics are attracting enormous\nattention for environmental stability and better energy conversion efficiency\nthrough enhanced charge separation, owing to loss of center of inversion\nsymmetry. We report on antiferroelectric-ferroelectric (AF-FE) phases of BZS\nthin film, grown with chemical vapor deposition (CVD), using\ntemperature-dependent Raman investigations and first-principles calculations.\nThe origin of FE phases is established from anomalous behavior of A7g ~ 300\ncm-1 and B1g5 ~ 420 cm-1 modes, which involves the vibration of atoms at apical\nsite of ZrS6 octahedra. Additionally, below 60 K, B1g1 and B2g2 ( ~ 85 cm-1)\nmodes appear whereas B12g (~ 60 cm-1) disappears to stabilize the Pnma\nstructure against ferroelectricity by local distortion. Here, B2g2 and B1g2\ninvolve vibrations of Ba atoms in AF manner while B1g1 involves, in addition,\nthe rotation of octahedra as well. Our first-principles calculations confirm\nthat FE appears as a result of loss of center of inversion symmetry in ZrS6\noctahedra due to existence of oxygen (O) impurities placed locally at apical\nsites of sulfur (S) atom.",
        "positive": "Electrically small metamaterial-based antennas - have we seen any real\n  practical benefits?: Electrically small metamaterial-based antennas are discussed from the\nindustrial point of view using mobile phones as the application example. It\nappears, that despite the interesting theoretical findings, the commercial\nacceptability of these antennas is low. Some of the issues possibly leading to\nthis situation are addressed. Discussion topics range from challenging\napplication environment, through the response of finite-size composite-material\nsamples, all the way to the required constructive criticism and acknowledgement\nof prior art. Selected issues are discussed in more details, and proposals how\nto possibly improve the commercial acceptability of metamaterial-based antennas\nare made."
    },
    {
        "anchor": "Dielectric behavior and impedance spectroscopy of Niobium substituted\n  Lanthanum based orthovanadates at high temperatures: We present the detailed study of the temperature dependent dielectric\nproperties, impedance spectroscopy and electrical conductivity of\nLaV$_{1-x}$Nb$_x$O$_4$ ($x=$ 0-1) samples prepared by the solid-state reaction\nmethod. The dielectric constant ($\\epsilon_r'$) increases (decreases) with\nincrease in the temperature (frequency); while, the magnitude of $\\epsilon_r'$\nremains almost invariant (order of 10$^4$ at 100~Hz and 600\\degree C) with $x$.\nThe single phase $x=$ 0 (monoclinic-monazite, $P2_1/n$) and $x =$ 1 (monoclinic\nfergusonite, $I2/a$) samples show the lower values of loss factor [tan$\\delta=$\n(4-8)] as compared to the $x=$ 0-0.8 samples [tan$\\delta=$(12-18)] having mixed\ntetragonal and monoclinic phases, which indicates the strong correlation\nbetween the crystal structure and the dielectric properties. The real part of\nimpedance decreases with both temperature and frequency, and the observed weak\nrelaxation remains almost unaltered with $x$. The imaginary part of impedance\nshows strong relaxation peaks shifting towards higher temperatures with\nfrequency, which is attributed to the effect of grains, grain boundaries, and\nelectrodes in the samples. The activation energy of the relaxation process is\nestimated to be 0.8-1.0~eV for the $x=$ 0-0.6 samples, and $\\approx$1.4~eV for\nthe $x=$ 0.8; whereas the $x=$ 1 sample shows two values ($\\approx$0.5~eV and\n$\\approx$1.0~eV) in the higher and lower temperature range, respectively.\nFurther, the change in total conductivity with the angular frequency, which\nfound to be in the range of 10$^{-3}$ to 10$^{-5}$~S/m, is fitted using the\nJonsher power law. The analysis suggests the OLPT model for all the samples,\nwhereas the $x$ = 1 sample exhibit a transition near 480\\degree C and at higher\ntemperatures it shows NSPT and QMT. This transition is corroborated by the\ntangent loss curves and may be associated with the change in structure.",
        "positive": "Comparison of variational real-space representations of the kinetic\n  energy operator: We present a comparison of real-space methods based on regular grids for\nelectronic structure calculations that are designed to have basis set\nvariational properties, using as a reference the conventional method of finite\ndifferences (a real-space method that is not variational) and the\nreciprocal-space plane-wave method which is fully variational. We find that a\nnew definition of the finite differences method [P. Maragakis, J. Soler, and E.\nKaxiras, Phys. Rev. B \\textbf{64}, 193101 (2001)] satisfies one of the two\nproperties of variational behaviour at the cost of larger errors than the\nconventional finite differences method. On the other hand, a technique which\nrepresents functions in a number of plane-waves which is independent of system\nsize, follows closely the plane-wave method and therefore also the criteria for\nvariational behaviour. Its application is only limited by the requirement of\nhaving functions strictly localised in regions of real-space but this is a\ncharacteristic of most modern real-space methods as they are designed to have a\ncomputational cost that scales linearly with system size."
    },
    {
        "anchor": "Universality of Electron Mobility in LaAlO$_3$/SrTiO$_3$ and bulk\n  SrTiO$_3$: Metallic LaAlO$_3$/SrTiO$_3$ (LAO/STO) interfaces attract enormous attention,\nbut the relationship between the electron mobility and the sheet electron\ndensity, $n_s$, is poorly understood. Here we derive a simple expression for\nthe three-dimensional electron density near the interface, $n_{3D}$, as a\nfunction of $n_s$ and find that the mobility for LAO/STO-based interfaces\ndepends on $n_{3D}$ in the same way as it does for bulk doped STO. It is known\nthat undoped bulk STO is strongly compensated with $N \\simeq 5 \\times\n10^{18}~\\rm{cm^{-3}}$ background donors and acceptors. In intentionally doped\nbulk STO with a concentration of electrons $n_{3D} < N$ background impurities\ndetermine the electron scattering. Thus, when $n_{3D} < N$ it is natural to see\nin LAO/STO the same mobility as in the bulk. On the other hand, in the bulk\nsamples with $n_{3D} > N$ the mobility collapses because scattering happens on\n$n_{3D}$ intentionally introduced donors. For LAO/STO the polar catastrophe\nwhich provides electrons is not supposed to provide equal number of random\ndonors and thus the mobility should be larger. The fact that the mobility is\nstill the same implies that for the LAO/STO the polar catastrophe model should\nbe revisited.",
        "positive": "B20-MnSi films grown on Si(100) substrates with magnetic skyrmion\n  signature: Magnetic skyrmions have been suggested as information carriers for future\nspintronic devices. As the first material with experimentally confirmed\nskyrmions, B20-type MnSi was the research focus for decades. Although B20-MnSi\nfilms have been successfully grown on Si(111) substrates, there is no report\nabout B20-MnSi films on Si(100) substrates, which would be more preferred for\npractical applications. In this letter, we present the first preparation of\nB20-MnSi on Si(100) substrates. It is realized by sub-second solid-state\nreaction between Mn and Si via flash-lamp annealing at ambient pressure. The\nregrown layer shows an enhanced Curie temperature of 43 K compared with bulk\nB20-MnSi. The magnetic skyrmion signature is proved in our films by magnetic\nand transport measurements. The millisecond-range flash annealing provides a\npromising avenue for the fabrication of Si-based skyrmionic devices."
    },
    {
        "anchor": "Carrier-induced Phase Transition in Metal Dichlorides XCl$_{2}$ (X: Fe,\n  Co, and Ni): We investigated the ground state of monolayer 1T-XCl$_{2}$ (X: Fe, Co, and\nNi) using the generalized Bloch theorem, which can generate ferromagnetic,\nspiral, and antiferromagnetic states. Each state was represented by a unique\nspiral vector that arranges the magnetic moment of magnetic atom in the\nprimitive unit cell. We found the ferromagnetic ground state for the FeCl$_{2}$\nand NiCl$_{2}$ while the spiral ground state appears for the CoCl$_{2}$. We\nalso showed that the ground state depends sensitively on the lattice constant.\nWhen the hole-electron doping was taken into account, we found the phase\ntransition, which involves the ferromagnetic, spiral, and antiferromagnetic\nstates, for all the systems. Since the spin-spin interaction in the monolayer\nmetal dichlorides is influenced by the competition between the direct exchange\nand the superexchange, we justify that the carrier concentration determines\nwhich interaction should dominate.",
        "positive": "Some further validations and comparison of the Bearing Area Model (BAM)\n  for adhesion of rough surfaces: In the present short note, we attempt further validations and comparisons of\na recent simple model for the estimate for adhesion between elastic (hard)\nrough solids with Gaussian multiple scales of roughness, BAM (Bearing Area\nModel) belonging to a DMT class of models. In one case, we use the GJP\n(Generalized Johnson Parameter) model, which is an empirical fit validated on\nthe same (and so far most extensive) set of data on which BAM was validated,\nnamely that of Pastewka and Robbins. In the second case, we compare with\nanother approximate DMT theory, that of Persson and Scaraggi, which turns out\nextremely close to the BAM model, despite much more complex: GJP however can\nlead to significant discrepancies."
    },
    {
        "anchor": "Insights of preferred growth, elemental and morphological properties of\n  BN/SnO2 composite for photocatalytic applications towards organic pollutants: Boron nitride (BN) has been explored these days because of its extraordinary\noptical, chemical and mechanical properties. BN is sensitive to its crystal\nstructure that slight change in lattice parameters enormously change its\nproperties. Present study deals with synthesis, characterization as well as\nphotocatalytic applications of BN-based composite. When boron nitride was mixed\nwith SnO2 having tetragonal crystal structure, dissociation into smaller sheets\noccurred and the material oriented to (102) plane. SnO2 particles attached both\nsides of BN sheets provided high surface area which make the material suitable\nfor catalytic process. Presence of large number of active sites leads to the\nformation of hydroxyl radicals in BN/SnO2 composite which helps during\ndegradation of organic and colourless pollutants i.e. methyl orange dye up-to\n~92% under 7 minutes and salicylic acid in 40 minutes to ~82%. Results\nsuggested that BN/SnO2 composite material possesses good capability for use in\nenvironmental as well as industrial applications.",
        "positive": "Creation of Tunable Homogeneous Thermal Cloak with Constant Conductivity: Invisible cloak has long captivated the popular conjecture and attracted\nintensive research in various communities of wave dynamics, e.g., optics,\nelectromagnetics, acoustics, etc. However, their inhomogeneous and extreme\nparameters imposed by transformation-optic method will usually require\nchallenging realization with metamaterials, resulting in narrow bandwidth,\nloss, polarization-dependence, etc. On the contrary, we demonstrate that\ntunable thermodynamic cloak can be achieved with homogeneous and finite\nconductivity only employing naturally available materials. The controlled\nlocalization of thermal distribution inside the coating layer has been\npresented, and it shows that an incomplete cloak can function perfectly.\nPractical realization of such homogeneous thermal cloak has been suggested by\nusing two naturally occurring conductive materials, which provides an\nunprecedentedly plausible way to flexibly realize flexible thermal cloak and\nmanipulate thermal flow."
    },
    {
        "anchor": "Assessing exchange-correlation functional performance for structure and\n  property predictions of oxyfluoride compounds from first principles: Motivated by the resurgence of electronic and optical property design in\nordered fluoride and oxyfluoride compounds, we present a density functional\ntheory (DFT) study on 19 materials with structures, ranging from simple to\ncomplex, and variable oxygen-to-fluorine ratios. We focus on understanding the\naccuracy of the exchange-correlation potentials ($V_{xc}$) to DFT for the\nprediction of structural, electronic, and lattice dynamical properties at four\ndifferent levels of theory, \\emph{i.e.}, the local density approximation (LDA),\ngeneralized gradient approximation (GGA), metaGGA, and hybrid functional level\nwhich includes fractions of exact exchange. We investigate in detail the\nmetaGGA functionals MS2 [Sun \\emph{et al}., Phys.\\ Rev.\\ Lett., \\textbf{111},\n106401 (2013)] and SCAN [Sun \\emph{et al}., Phys.\\ Rev.\\ Lett., \\textbf{115},\n036402 (2015)], and show that although the metaGGAs show improvements over the\nLDA and GGA functionals in describing the electronic structure and phonon\nfrequencies, the static structural properties of fluorides and oxyfluorides are\noften more accurately predicted by the GGA-level functional PBEsol. Results\nfrom LDA calculations are unsatisfactory for any compound regardless of oxygen\nconcentration. PBEsol or HSE06 gives good performance in all oxide or all\nfluoride compounds. For the oxyfluorides, PBEsol is consistently more accurate\nfor structural properties across all oxygen concentrations, however, we stress\nthe need for detailed property assessment with various functionals for\noxyfluorides with variable composition. The \"best\" functional is anticipated to\nbe more strongly dependent on the property of interest. Our study provides\nuseful insights in selecting an $V_{xc}$ that achieves the best performance\ncomprise, enabling more accurate predictive design of functional fluoride-based\nmaterials with density functional theory.",
        "positive": "The Zoo of Non-Fourier Heat Conduction Models: The Fourier heat conduction model is valid for most macroscopic problems.\nHowever, it fails when the wave nature of the heat propagation or time lags\nbecome dominant and the memory or/and spatial non-local effects significant --\nin ultrafast heating (pulsed laser heating and melting), rapid solidification\nof liquid metals, processes in glassy polymers near the glass transition\ntemperature, in heat transfer at nanoscale, in heat transfer in a solid state\nlaser medium at the high pump density or under the ultra-short pulse duration,\nin granular and porous materials including polysilicon, at extremely high\nvalues of the heat flux, in heat transfer in biological tissues.\n  In common materials the relaxation time ranges from $10^{-8}$ to $10^{-14}$\nsec, however, it could be as high as 1 sec in the degenerate cores of aged\nstars and its reported values in granular and biological objects varies up to\n30 sec. The paper considers numerous non-Fourier heat conduction models that\nincorporate time non-locality for materials with memory (hereditary materials,\nincluding fractional hereditary materials) or/and spatial non-locality, i.e.\nmaterials with non-homogeneous inner structure."
    },
    {
        "anchor": "Predicted thermoelectric properties of olivine-type Fe2GeCh4 (Ch = S, Se\n  and Te): We present here the thermoelectric properties of olivine-type Fe2GeCh4 (Ch =\nS, Se and Te) using the linear augmented plane wave method based on first\nprinciples density functional calculations. The calculated transport properties\nusing the semi-local Boltzmann transport equation reveal very high thermopower\nfor both S and Se-based compounds compared to their Te counterparts. The main\nreason for this high thermopower is the quasi-flat nature of the bands at the\nvalence and conduction band edges. The calculated thermopower of Fe2GeCh4 is in\ngood agreement with the experimental reports at room temperature, with the\ncarrier concentration around 1018-1019cm-3. All the investigated systems show\nan anisotropic nature in their electrical conductivity, resulting in a value\nless than the order of 102 along the a-axis compared to the b- and c-axes.\nAmong the studied compounds, Fe2GeS4 and Fe2GeSe4 emerge as promising\ncandidates with good thermoelectric performance.",
        "positive": "Atomically flat reconstructed rutile TiO2(001) surfaces for oxide film\n  growth: The availability of low-index rutile TiO2 single crystal substrates with\natomically flat surfaces is essential for enabling epitaxial growth of rutile\ntransition metal oxide films. The high surface energy of the rutile (001)\nsurface often leads to surface faceting, which precludes the sputter and\nannealing treatment commonly used for the preparation of clean and atomically\nflat TiO2(110) substrate surfaces. In this work, we reveal that stable and\natomically flat rutile TiO2(001) surfaces can be prepared with an atomically\nordered reconstructed surface already during a furnace annealing treatment in\nair. We tentatively ascribe this result to the decrease in surface energy\nassociated with the surface reconstruction, which removes the driving force for\nfaceting. Despite the narrow temperature window where this morphology can\ninitially be formed, we demonstrate that it persists in homoepitaxial growth of\nTiO2(001) thin films. The stabilization of surface reconstructions that prevent\nfaceting of high-surface-energy crystal faces may offer a promising avenue\ntowards the realization of a wider range of high quality epitaxial transition\nmetal oxide heterostructures."
    },
    {
        "anchor": "Electrical switching of antiferromagnetic CoO | Pt across the N\u00e9el\n  temperature: One of the most important challenges in antiferromagnetic spintronics is the\nread-out of the N\\'eel vector state. High current densities up to 10$^8$\nAcm$^{-2}$ used in the electrical switching experiments cause notorious\ndifficulty in distinguishing between magnetic and thermal origins of the\nelectrical signals. To overcome this problem, we present a temperature\ndependence study of the transverse resistance changes in the switching\nexperiment with CoO|Pt devices. We demonstrate the possibility to extract a\npattern of spin Hall magnetoresistance for current pulses density of $5 \\times\n10^7$ Acm$^{-2}$ that is present only below the N\\'eel temperature and does not\nfollow a trend expected for thermal effects. This is the compelling evidence\nfor the magnetic origin of the signal, which is observed using purely\nelectrical techniques. We confirm these findings by complementary experiments\nin an external magnetic field. Such an approach can allow determining the\noptimal conditions for switching antiferromagnets and be very valuable when no\nimaging techniques can be applied to verify the origin of the electrical\nsignal.",
        "positive": "Ultrasonic investigation of the interaction hydrogen-dislocations in\n  copper crystals: In this paper we present experimental data of ultrasonic velocity and\nattenuation obtained in a high purity crystalline sample of cooper hydrogenated\nby gaseous charge. The sample is oriented in the <111> crystallographic\ndirection and aged for this work in three stages between 64 and 97 days. The\nresults indicate that the hydrogen is mainly segregated at the dislocation\ncore, inhibiting the Hydrogen Snoek-K\\\"oster relaxations verified at earlier\naging stages. Despite of this, a contribution to viscosity in the kink-chain\nresonance is provided by the mobile hydrogen in the dislocations core by its\nside movement along the dislocation line. At temperatures at which the hydrogen\nbegins to freeze in the lattice the geometrical kinks find a gradual increase\non the hindering of their movements along dislocation lines, becoming immobile\nwhen the hydrogen is completely frozen in the crystal, anchoring the\ndislocations in short loops. Although the viscosity associated with the mobile\nhydrogen is removed, the resonance associated with geometrical kinks is not\ncompletely cancelled. The interaction hydrogen-dislocation can be fully\ndescribed in terms of kinks in dislocations."
    },
    {
        "anchor": "High resolution Kerr microscopy study of exchange bias phenomena in\n  FePt/Fe exchange spring magnets: Magnetization and magnetic microstructure of top soft magnetic layer (Fe),\nwhich is exchange spring coupled to bottom hard magnetic layer ($L1_0$ FePt) is\nstudied using high resolution Kerr microscopy. When the sample (FePt/Fe) is at\nremanent condition of hard magnetic layer, considerable shifting of Fe layer\nhysteresis loop from centre i.e., exchange bias phenomena is observed. It is\nobserved that one can tune the magnitude of exchange bias shift by reaching the\nremanent state from different saturating fields ($H_{SAT}$) and also by varying\nthe angle between measuring field and $H_{SAT}$. The M-H loops and domain\nimages of top soft Fe layer demonstrates unambiguously that soft magnetic layer\nat remanent state in such exchange coupled system is having unidirectional\nanisotropy. An analogy is drawn and the observations are explained in terms of\nthe mostly accepted models of exchange bias phenomena exhibited by bilayers\nconsisting of ferromagnetic(FM) and anti-ferromagnetic (AFM) layers, when the\nAFM layer is field cooled across $N\\acute{e}el$ transition temperature.",
        "positive": "Isotope Exchange Raman Spectroscopy (IERS): a novel technique to probe\n  physicochemical processes $in$ $situ$: We have developed a novel in situ methodology for the direct study of mass\ntransport properties in oxides with spatial and unprecedented time resolution,\nbased on Raman spectroscopy coupled to isothermal isotope exchanges. Changes in\nthe isotope concentration, resulting in a Raman frequency shift, can be\nfollowed in real time, not accessible by conventional methods, enabling\ncomplementary insights for the study of ion transport properties of electrode\nand electrolyte materials for advanced solid-state electrochemical devices. The\nproof of concept and strengths of isotope exchange Raman spectroscopy (IERS)\nare demonstrated by studying the oxygen isotope back-exchange in\ngadolinium-doped ceria (CGO) thin films. Resulting oxygen self-diffusion and\nsurface exchange coefficients are compared to conventional time-of-flight\nsecondary ion mass spectrometry (ToF-SIMS) characterisation and literature\nvalues, showing good agreement, while at the same time providing additional\ninsight, challenging established assumptions. IERS captivates through its\nrapidity, simple setup, non-destructive nature, cost effectiveness and\nversatile fields of application and thus can readily be integrated as new\nstandard tool for in situ and operando characterization in many laboratories\nworldwide. The applicability of this method is expected to consolidate our\nunderstanding of elementary physicochemical processes and impact various\nemerging fields including solid oxide cells, battery research and beyond."
    },
    {
        "anchor": "Anisotropic magnetoresistive properties of La_{1-x}Ca_{x}MnO_{3} (x\n  \\approx 1/3) film at temperatures far below the Curie temperature: A sharp distinction between magnetoresistance (MR) behavior for the magnetic\nfields applied perpendicular (H_{perp}) and parallel (H_{par}) to the film\nplane is found in colossal-magnetoresistance film La_{1-x}Ca_{x}MnO_{3} (x\n\\approx 3). At increasing of H_{perp} the MR is first negative (at H_{perp} < 4\nkOe), then positive (4 kOe < H_{perp} < 12 kOe), and then negative again\n(H_{perp} > 12 kOe). At increasing of H_{par} the MR is positive below H_{par}\n\\simeq 6 kOe and negative above it. In both cases the magnetic field was\nperpendicular to the current. The anisotropic behavior of this kind occurs only\nat low temperatures (T < 18 K) and is quite different from the results of\nprevious studies.",
        "positive": "Pressure-Induced Critical Influences on Workpiece-Tool Thermal\n  Interaction in High Speed Dry Machining of Titanium: Cutting tools are subject to extreme thermal and mechanical loads during\noperation. The state of loading is intensified in dry cutting environment\nespecially when cutting the so called hard-to-cut-materials. Although, the\neffect of mechanical loads on tool failure have been extensively studied,\ndetailed studies on the effect of thermal loads on the deterioration of the\ncutting tool are rather scarce. In this paper we study failure of coated\ncarbide tools due to thermal loading. The study emphasizes the role assumed by\nthe thermo-physical properties of the tool material in enhancing or preventing\nmass attrition of the cutting elements within the tool. It is shown that within\na comprehensive view of the nature of conduction in the tool zone, thermal\nconduction is not solely affected by temperature. Rather it is a function of\nthe so called thermodynamic forces. These are the stress, the strain, strain\nrate, rate of temperature rise, and the temperature gradient. Although that\nwithin such consideration description of thermal conduction is non-linear, it\nis beneficial to employ such a form because it facilitates a full mechanistic\nunderstanding of thermal activation of tool wear."
    },
    {
        "anchor": "Incorporation of magnetic nanoparticles into lamellar\n  polystyrene-b-poly(n-butyl methacrylate) diblock copolymer films: influence\n  of the chain end-groups on nanostructuration: In this article, we present new samples of lamellar magnetic nanocomposites\nbased on the self-assembly of a polystyrene-b-poly(n-butyl methacrylate)\ndiblock copolymer synthesized by atom transfer radical polymerization. The\npolymer films were loaded with magnetic iron oxide nanoparticles covered with\npolystyrene chains grown by surface initiated-ATRP. The nanostructuration of\nthe pure and magnetically loaded copolymer films on silicon was studied by\natomic force microscopy, ellipsometry, neutron reflectivity and contact angle\nmeasurement. The present study highlights the strong influence of the copolymer\nextremity - driven itself by the choice of the ATRP chemical route - on the\norder of the repetition sequences of the blocks in the multi-lamellar films. In\naddition, a narrower distribution of the nanoparticles' sizes was examined as a\ncontrol parameter of the SI-ATRP reaction.",
        "positive": "Thickness dependence of dynamic and static magnetic properties of pulsed\n  laser deposited La$_{0.7}$Sr$_{0.3}$MnO$_3$ films on SrTiO$_3$(001): We present a comprehensive study of the thickness dependence of static and\nmagneto-dynamic magnetic properties of La$_{0.7}$Sr$_{0.3}$MnO$_3$. Epitaxial\npulsed laser deposited La$_{0.7}$Sr$_{0.3}$MnO$_3$ / SrTiO$_3$(001) thin films\nin the range from 3 unit cells (uc) to 40 uc (1.2 - 16 nm) have been\ninvestigated through ferromagnetic resonance spectroscopy (FMR) and SQUID\nmagnetometry at variable temperature. Magnetodynamically, three different\nthickness, $d$, regimes are identified: 20 uc $\\lesssim d$ uc where the system\nis bulk like, a transition region 8 uc $\\le d \\lesssim 20$ uc where the FMR\nline width and position depend on thickness and $d=6$ uc which displays\nsignificantly altered magnetodynamic properties, while still displaying bulk\nmagnetization. Magnetization and FMR measurements are consistent with a\nnonmagnetic volume corresponding to $\\sim$ 4 uc. We observe a reduction of\nCurie temperature ($T_C$) with decreasing thickness, which is coherent with a\nmean field model description. The reduced ordering temperature also accounts\nfor the thickness dependence of the magnetic anisotropy constants and resonance\nfields. The damping of the system is strongly thickness dependent, and is for\nthin films dominated by thickness dependent anisotropies, yielding both a\nstrong 2-magnon scattering close to $T_c$ and a low temperature broadening. For\nthe bulk like samples a large part of the broadening can be linked to spread in\nmagnetic anisotropies attributed to crystal imperfections/domain boundaries of\nthe bulk like film."
    },
    {
        "anchor": "Disentangling electronic transport and hysteresis at individual grain\n  boundaries in hybrid perovskites via automated scanning probe microscopy: Underlying the rapidly increasing photovoltaic efficiency and stability of\nmetal halide perovskites (MHPs) is the advance in the understanding of the\nmicrostructure of polycrystalline MHP thin film. Over the past decade, intense\nefforts have aimed to understand the effect of microstructure on MHP\nproperties, including chemical heterogeneity, strain disorder, phase impurity,\netc. It has been found that grain and grain boundary (GB) are tightly related\nto lots of microscale and nanoscale behavior in MHP thin film. Atomic force\nmicroscopy (AFM) is widely used to observe grain and boundary structures in\ntopography and subsequently to study the correlative surface potential and\nconductivity of these structures. For now, most AFM measurements have been\nperformed in imaging mode to study the static behavior, in contrast, AFM\nspectroscopy mode allows us to investigate the dynamic behavior of materials,\ne.g. conductivity under sweeping voltage. However, a major limitation of AFM\nspectroscopy measurements is that it requests manual operation by human\noperators, as such only limited data can be obtained, hindering systematic\ninvestigations of these microstructures. In this work, we designed a workflow\ncombining the conductive AFM measurement with a machine learning (ML) algorithm\nto systematically investigate grain boundaries in MHPs. The trained ML model\ncan extract GBs locations from the topography image, and the workflow drives\nthe AFM probe to each GB location to perform a current-voltage (IV) curve\nautomatically. Then, we are able to IV curves at all GB locations, allowing us\nto systematically understand the property of GBs. Using this method, we\ndiscover that the GB junction points are more photoactive, while most previous\nworks only focused on the difference between GB and grains.",
        "positive": "Semi-adsorption-controlled growth window for half Heusler FeVSb\n  epitaxial films: The electronic, magnetic, thermoelectric, and topological properties of\nHeusler compounds (composition $XYZ$ or $X_2 YZ$) are highly sensitive to\nstoichiometry and defects. Here we establish the existence and experimentally\nmap the bounds of a \\textit{semi} adsorption-controlled growth window for\nsemiconducting half Heusler FeVSb films, grown by molecular beam epitaxy (MBE).\nWe show that due to the high volatility of Sb, the Sb stoichiometry is\nself-limiting for a finite range of growth temperatures and Sb fluxes, similar\nto the growth of III-V semiconductors such as GaSb and GaAs. Films grown within\nthis window are nearly structurally indistinguishable by X-ray diffraction\n(XRD) and reflection high energy electron diffraction (RHEED). The highest\nelectron mobility and lowest background carrier density are obtained towards\nthe Sb-rich bound of the window, suggesting that Sb-vacancies may be a common\ndefect. Similar \\textit{semi} adsorption-controlled bounds are expected for\nother ternary intermetallics that contain a volatile species $Z=$\\{Sb, As,\nBi\\}, e.g., CoTiSb, LuPtSb, GdPtBi, and NiMnSb. However, outstanding challenges\nremain in controlling the remaining Fe/V ($X/Y$) transition metal\nstoichiometry."
    },
    {
        "anchor": "Sub-nanosecond free carrier recombination in an indirectly excited\n  quantum-well heterostructure: Nanometer-thick quantum-well structures are quantum model systems offering a\nfew discrete unoccupied energy states that can be impulsively filled and that\nrelax back to equilibrium predominantly via spontaneous emission of light. Here\nwe report on the response of an indirectly excited quantum-well\nheterostructure, probed by means of time and frequency resolved\nphotoluminescence spectroscopy. This experiment provides access to the\nsub-nanosecond evolution of the free electron density, indirectly injected in\nthe quantum-wells. In particular, the modelling of the time-dependent\nphotoluminescence spectra unveils the time evolution of the temperature and of\nthe chemical potentials for electrons and holes, from which the sub-nanosecond\ntime-dependent electron density is determined. This information allows to prove\nthat the recombination of excited carriers is mainly radiative and bimolecular\nat early delays after excitation, while, as the carrier density decreases, a\nmonomolecular and non-radiative recombination channel becomes relevant. Access\nto the sub-nanosecond chronology of the mechanisms responsible for the\nrelaxation of charge carriers provides a wealth of information for designing\nnovel luminescent devices with engineered spectral and temporal behavior.",
        "positive": "Spin coupling around a carbon atom vacancy in graphene: We investigate the details of the electronic structure in the neighborhoods\nof a carbon atom vacancy in graphene by employing magnetization-constrained\ndensity-functional theory on periodic slabs, and spin-exact, multi-reference,\nsecond-order perturbation theory on a finite cluster. The picture that emerges\nis that of two local magnetic moments (one \\pi-like and one \\sigma-like)\ndecoupled from the \\pi- band and coupled to each other. We find that the ground\nstate is a triplet with a planar equilibrium geometry where an apical C atom\nopposes a pentagonal ring. This state lies ~0.2 eV lower in energy than the\nopen-shell singlet with one spin flipped, which is a bistable system with two\nequivalent equilibrium lattice configurations (for the apical C atom above or\nbelow the lattice plane) and a barrier ~0.1 eV high separating them.\nAccordingly, a bare carbon-atom vacancy is predicted to be a spin-one\nparamagnetic species, but spin-half paramagnetism can be accommodated if\nbinding to foreign species, ripples, coupling to a substrate, or doping are\ntaken into account."
    },
    {
        "anchor": "All Electronic Isolator Action Device Based on Negative Refractive\n  Heterostructure Bi-Crystal with Field Induced Asymmetry: It has been discovered that heterostructure bicrystal arrangements lead to\nfield asymmetry in guided wave structures. Here a study is conducted over a\nrange of nominal permittivity values to see if the effect is present in widely\nvarying dielectric materials. Marked shifts of the field distribution occurs in\nsome cases, and this can be the basis of an all electronic isolator. Such an\nall electronic device could be fixed or even constructed as a control component\nusing materials with electrostatically controllable permittivity. Distributions\nhave been obtained to demonstrate the effect using an anisotropic Green's\nfunction solver.",
        "positive": "Epitaxial Ferromagnetic Nanoislands of Cubic GdN in Hexagonal GaN: Periodic structures of GdN particles encapsulated in a single crystalline GaN\nmatrix were prepared by plasma assisted molecular beam epitaxy. High resolution\nX-ray diffractometery shows that GdN islands, with rock salt structure are\nepitaxially oriented to the wurtzite GaN matrix. Scanning transmission electron\nmicroscopy combined with in-situ reflection high energy electron diffraction\nallows for the study of island formation dynamics, which occurs after 1.2\nmonolayers of GdN coverage. Magnetometry reveals two ferromagnetic phases, one\ndue to GdN particles with Curie temperature of 70K and a second, anomalous room\ntemperature phase."
    },
    {
        "anchor": "Increased magnetic damping of a single domain wall and adjacent magnetic\n  domains detected by spin torque diode in a nanostripe: We use spin-torque resonance to probe simultaneously and separately the\ndynamics of a magnetic domain wall and of magnetic domains in a nanostripe\nmagnetic tunnel junction. Thanks to the large associated resistance variations\nwe are able to analyze quantitatively the resonant properties of these single\nnanoscale magnetic objects. In particular, we find that the magnetic damping of\nboth domains and domain walls is doubled compared to the damping value of their\nhost magnetic layer. We estimate the contributions to damping arising from\ndipolar couplings between the different layers in the junction and from the\nintralayer spin pumping effect. We find that they cannot explain the large\ndamping enhancement that we observe. We conclude that the measured increased\ndamping is intrinsic to large amplitudes excitations of spatially localized\nmodes or solitons such as vibrating or propagating domain walls",
        "positive": "Spontaneous spin selectivity in chiral molecules at the interface: Chirality-induced spin selectivity (CISS) has been extensively studied over\nthe past two decades. While current-induced spin polarization in chiral\nmolecules is widely recognized as the fundamental principle of the CISS, only a\nfew studies have been reported on bias-current-free CISS, where there is no\nbias electric current in chiral molecules. Recent studies on the\nchirality-induced exchange bias and current-in-plane magnetoresistance (CIP-MR)\neffects using chiral molecule/ferromagnet bilayer systems indicate that chiral\nmolecules at the interface possess thermally driven broken-time-reversal\nsymmetry, which induces bias-current-free CISS, i.e. a spontaneous effective\nmagnetic field in the system. In this paper, we briefly review CISS-related\nphenomena in terms of the symmetry and discuss the mechanism of\nbias-current-free CISS. We also discuss the possibility of the linear\nmagnetoelectric effect of chiral molecules, which arises from the spin\npolarization at the edges of molecules with metallic contacts, and its\npotential impact on the observed CISS phenomena."
    },
    {
        "anchor": "Do thermoelectric generator modules degrade due to nickel diffusion: The paper shows by calculation that the diffusion of nickel even for 50 years\ndoes not lead to degradation of thermoelectric generator modules. In the\nprocess, we used the theory of composites to calculate the electrical contact\nresistance, our own diffusion theory of electrical contact resistance, as well\nas the method for approximating the temperature dependences of thermoelectric\nmaterial characteristics from the experimental data. When using the above\nmethod, it was assumed that the main mechanism of scattering of free charge\ncarriers in a thermoelectric material is their scattering on the deformation\npotential of acoustic phonons with a free path length independent of energy but\ninversely proportional to temperature, and the main mechanism of phonon\nscattering is phonon-phonon scattering with Umklapp, which is not affected by\nthe nickel impurity in the thermoelectric material. Thus, it was believed that\nthe role of nickel is reduced only to a change in the concentration of free\ncharge carriers in the material.",
        "positive": "Revisiting the Mn-doped Ge using the Heyd-Scuseria-Ernzerhof hybrid\n  functional: We perform a comparative \\textit{ab-initio} study of Mn-doped Germanium\nsemiconductor using the Perdew-Burke-Ernzerhof (PBE) exchange-correlation\nfunctional, DFT+$U$ and Heyd-Scuseria-Ernzerhof hybrid functional (HSE). We\nshow that the HSE functional is able to correctly account for the relevant\nground state properties of the host matrix as well as of Mn-doped\nsemiconductor. Although the DFT+$U$ and the HSE description are very similar,\nsome differences still remain. In particular, the half-metallicity is lost\nusing DFT+$U$ when a suitable $U$ value, tuned to recover the photoemission\nspectra, is employed. For comparison, we also discuss the case of Mn in\nSilicon."
    },
    {
        "anchor": "Antiferromagnetic I-Mn-V semiconductors: After decades of research, the low Curie temperature of ferromagnetic\nsemiconductors remains the key problem in the development of magnetic\nsemiconductor spintronic technologies. Removing this roadblock might require a\nchange of the field's basic materials paradigm by looking beyond ferromagnets.\nRecent studies of relativistic magnetic and magnetotransport anisotropy\neffects, which in principle are equally well present in materials with\nferromagnetically and antiferromagnetically ordered spins, have inspired our\nsearch for antiferromagnetic semiconductors suitable for high-temperature\nspintronics. Since these are not found among the magnetic counterparts of\ncommon III-V or II-VI semi- conductors, we turn the attention in this paper to\nhigh N \\'eel temperature I-II-V magnetic compounds whose electronic structure\nhas not been previously identified. Our combined experimental and theoretical\nwork on LiMnAs provides basic prerequisite for the systematic research of this\nclass of materials by demonstrating the feasibility to grow single crystals of\ngroup-I alkali metal compounds by molecular beam epitaxy, by demonstrating the\nsemiconducting band structure of the I-Mn-V's, and by analyzing their\nspin-orbit coupling characteristics favorable for spintronics.",
        "positive": "Critical Behavior and Anisotropy in Single Crystal SrRuO$_3$: The magnetization of single crystal SrRuO3 is studied as a function of\ntemperature along different crystallographic directions. The magnetocrystalline\nanisotropy and behavior near the critical transition temperature are analyzed\nin detail. The magnetization vs temperature is found to vary more like $T^2$\nrather than $T^{3/2}$ expected for spin waves."
    },
    {
        "anchor": "Tuning flexoelectricty and electronic properties of zig-zag graphene\n  nanoribbons by functionalization: The flexoelectric and electronic properties of zig-zag graphene nanoribbons\nare explored under mechanical bending using state of the art first principles\ncalculations. A linear dependence of the bending induced out of plane\npolarization on the applied strain gradient is found. The inferior\nflexoelectric properties of graphene nanoribbons can be improved by more than\ntwo orders of magnitude by hydrogen and fluorine functionalization (CH and CF\nnanoribbons). A large out of plane flexoelectric effect is predicted for CF\nnanoribbons. The origin of this enhancement lies in the electro-negativity\ndifference between carbon and fluorine atoms, which breaks the out of plane\ncharge symmetry even for a small strain gradient. The flexoelectric effect can\nbe further improved by co-functionalization with hydrogen and fluorine (CHF\nJanus-type nanoribbon), where a spontaneous out of plane dipole moment is\nformed even for flat nanoribbons. We also find that bending can control the\ncharge localization of valence band maxima and therefore enables the tuning of\nthe hole effective masses and band gaps. These results present an important\nadvance towards the understanding of flexoelectric and electronic properties of\nhydrogen and fluorine functionalized graphene nanoribbons, which can have\nimportant implications for flexible electronic applications.",
        "positive": "Synthesis dependent characteristics of Sr1-xMnxTiO3 (x=0.03, 0.05, 0.07\n  and 0.09): Sr1-xMnxTiO3 (where x = 0.03, 0.05, 0.07 and 0.09) was synthesized via\ndifferent routes that include solid-state, oxalate precipitation and freeze\ndrying. In oxalate precipitation technique, compositions corresponding to 3 and\n5 mol % doping of Mn were monophasic whereas the higher compositions revealed\nthe presence of the secondary phases such as MnO, Mn3O4 etc., as confirmed by\nhigh resolution X-ray diffraction (XRD) studies. The decomposition behavior of\nthe precursors prepared using oxalate precipitation method corresponding to the\nabove mentioned compositions was studied. Nanopowders of compositions\npertaining to 5 to 9 mol % of Mn doping were obtained using freeze-drying\ntechnique. The average crystallite size of these nanopowders was found to be in\nthe 35 to 65 nm range. The microstructural studies carried out on the sintered\nceramics, fabricated using powders synthesized by different routes established\nthe fine grained nature (< 1 microm) of the one obtained by freeze drying\nmethod. Raman scattering studies were carried out in order to complement the\nobservations made from XRD regarding the phase purity. The dielectric\nproperties of the ceramics obtained by different synthesis routes were studied\nin the 80 - 300 K temperature range at 100 kHz and the effect of grain size has\nbeen discussed."
    },
    {
        "anchor": "Tunable Multifunctional Topological Insulators in Ternary Heusler\n  Compounds: Recently the Quantum Spin Hall effect (QSH) was theoretically predicted and\nexperimentally realized in a quantum wells based on binary semiconductor\nHgTe[1-3]. QSH state and topological insulators are the new states of quantum\nmatter interesting both for fundamental condensed matter physics and material\nscience[1-11]. Many of Heusler compounds with C1b structure are ternary\nsemiconductors which are structurally and electronically related to the binary\nsemiconductors. The diversity of Heusler materials opens wide possibilities for\ntuning the band gap and setting the desired band inversion by choosing\ncompounds with appropriate hybridization strength (by lattice parameter) and\nthe magnitude of spin-orbit coupling (by the atomic charge). Based on the\nfirst-principle calculations we demonstrate that around fifty Heusler compounds\nshow the band inversion similar to HgTe. The topological state in these\nzero-gap semiconductors can be created by applying strain or by designing an\nappropriate quantum well structure, similar to the case of HgTe. Many of these\nternary zero-gap semiconductors (LnAuPb, LnPdBi, LnPtSb and LnPtBi) contain the\nrare earth element Ln which can realize additional properties ranging from\nsuperconductivity (e. g. LaPtBi[12]) to magnetism (e. g. GdPtBi[13]) and\nheavy-fermion behavior (e. g. YbPtBi[14]). These properties can open new\nresearch directions in realizing the quantized anomalous Hall effect and\ntopological superconductors.",
        "positive": "Defects in metal-organic frameworks: a compromise between adsorption and\n  stability?: Defect engineering has arisen as a promising approach to tune and optimise\nthe adsorptive performance of metal-organic frameworks. However, the balance\nbetween enhanced adsorption and structural stability remains an open question.\nHere both CO2 adsorption capacity and mechanical stability are calculated for\nthe zirconium-based UiO-66, which is subject to systematic variations of defect\nscenarios. Modulator-dependence, defect concentration and heterogeneity are\nexplored in isolation. Mechanical stability is shown to be compromised at high\npressures where uptake is enhanced with an increase in defect concentration.\nNonetheless this reduction in stability is minimised for reo type defects and\ndefects with trifluoroacetate substitution. Finally, heterogeneity and\nauxeticity may also play a role in overcoming the compromise between adsorption\nand stability."
    },
    {
        "anchor": "GPAW: open Python package for electronic-structure calculations: We review the GPAW open-source Python package for electronic structure\ncalculations. GPAW is based on the projector-augmented wave method and can\nsolve the self-consistent density functional theory (DFT) equations using three\ndifferent wave-function representations, namely real-space grids, plane waves,\nand numerical atomic orbitals. The three representations are complementary and\nmutually independent and can be connected by transformations via the real-space\ngrid. This multi-basis feature renders GPAW highly versatile and unique among\nsimilar codes. By virtue of its modular structure, the GPAW code constitutes an\nideal platform for implementation of new features and methodologies. Moreover,\nit is well integrated with the Atomic Simulation Environment (ASE) providing a\nflexible and dynamic user interface. In addition to ground-state DFT\ncalculations, GPAW supports many-body GW band structures, optical excitations\nfrom the Bethe-Salpeter Equation (BSE), variational calculations of excited\nstates in molecules and solids via direct optimization, and real-time\npropagation of the Kohn-Sham equations within time-dependent DFT. A range of\nmore advanced methods to describe magnetic excitations and non-collinear\nmagnetism in solids are also now available. In addition, GPAW can calculate\nnon-linear optical tensors of solids, charged crystal point defects, and much\nmore. Recently, support of GPU acceleration has been achieved with minor\nmodifications of the GPAW code thanks to the CuPy library. We end the review\nwith an outlook describing some future plans for GPAW.",
        "positive": "Tunable Plasmon Molecules in Overlapping Nanovoids: Coupled and shape-tailored metallic nanoparticles are known to exhibit\nhybridized plasmon resonances. This Letter discuss the optical properties of a\ncomplementary system formed by overlapped nanovoid dimers buried in gold and\nfilled with silica. This is an alternative route for plasmon engineering that\nbenefits from vanishing radiation losses. Our analysis demonstrates the\npossibility of designing artificial plasmon molecules on the basis of void\nplasmon hybridization, which allows fine mode tuning by varying the overlap\nbetween voids. The proposed structures could find application to both signal\nprocessing through buried optical elements and tunable-plasmon biosensing."
    },
    {
        "anchor": "General method for atomistic spin-lattice dynamics with first principles\n  accuracy: We present a computationally efficient general first-principles based method\nfor spin-lattice simulations for solids. Our method is based on a combination\nof atomistic spin dynamics and molecular dynamics, expressed through a\nspin-lattice Hamiltonian where the bilinear magnetic term is expanded to second\norder in displacement, and all parameters are computed using density functional\ntheory. The effect of first-order spin-lattice coupling on the magnon and\nphonon dispersion in bcc Fe is reported as an example, and is seen to be in\ngood agreement with previous simulations performed with an empirical potential\napproach. In addition, we also illustrate the abilities of our method on a more\nconceptual level, by exploring dissipation-free spin and lattice motion in\nsmall magnetic clusters (a dimer, trimer and quadmer). Our method opens the\ndoor for quantitative description and understanding of the microscopic origin\nof many fundamental phenomena of contemporary interest, such as ultrafast\ndemagnetization, magnetocalorics, and spincaloritronics.",
        "positive": "Precise Layer-Dependent Electronic Structure of MBE-Grown PtSe$_2$: Two-dimensional (2D) platinum diselenide (PtSe$_2$) has received significant\nattention for 2D transistor applications due to its high mobility. Here, using\nmolecular beam epitaxy, we investigate the growth of 2D PtSe$_2$ on highly\noriented pyrolytic graphite (HOPG) and unveil their electronic properties via\nX-ray photoelectron spectroscopy, Raman spectra, and scanning tunnelling\nmicroscopy/spectroscopy as well as density functional theory (DFT)\ncalculations. PtSe$_2$ adopts a layer-by-layer growth mode on HOPG and shows a\ndecreasing band gap with increasing layer number. For the layer numbers from\none to four, PtSe$_2$ has band gaps of $2.0 \\pm 0.1$, $1.1 \\pm 0.1$, $0.6 \\pm\n0.1$ and $0.20 \\pm 0.1$ eV, respectively, and becomes semimetal from the fifth\nlayer. DFT calculations reproduce the layer-dependent evolution of both the\nband gap and band edges, suggest an indirect band-gap structure, and elucidate\nthe underlying physics at the atomic level."
    },
    {
        "anchor": "Rigidity-based approach to the boson peak in amorphous solids: from\n  sphere packing to amorphous silica: Glasses have a large excess of low-frequency vibrational modes in comparison\nwith continuous elastic body, the so-called Boson Peak, which appears to\ncorrelate with several crucial properties of glasses, such as transport or\nfragility. I review recent results showing that the Boson Peak is a necessary\nconsequence of the weak connectivity of the solid. I explain why in assemblies\nrepulsive spheres the boson peak shifts up to zero frequency as the pressure is\nlowered toward the jamming threshold, and derive the corresponding exponent. I\nshow how these ideas capture the main low-frequency features of the vibrational\nspectrum of amorphous silica. These results extend arguments of Phillips on the\npresence of floppy modes in under-constrained covalent networks to glasses\nwhere the covalent network is rigid, or when interactions are purely radial.",
        "positive": "Electronic Properties and Interlayer Interactions in Antimony Oxide\n  Homo- and Heterobilayers: Antimony shows promise as a two-dimensional (2D) mono-elemental crystal,\nreferred to as antimonene. When exposed to ambient conditions, antimonene\nlayers react with oxygen, forming new crystal structures, leading significant\nchanges in electronic properties. These changes are influenced by the degree of\noxidation. Utilizing Density Functional Theory (DFT) calculations, stable\nconfigurations of bilayer antimony oxide and their corresponding electronic\nproperties are studied. Additionally, different stacking arrangements and their\neffects on the physical properties of the materials are investigated.\nFurthermore, the analysis encompasses strain-free hetero-bilayers containing\nboth pristine and oxidized antimonene layers, aiming to understand the\ninterplay between these materials and their collective impact on the bilayer\nproperties. Our results provide insight into how the properties of\nantimony-based bilayer structures can be modified by adjusting stoichiometry\nand stacking configurations."
    },
    {
        "anchor": "Simulation of attosecond transient soft X-ray absorption in solids using\n  generalized Kohn-Sham real-time TDDFT: Time-dependent density functional theory (TDDFT) simulations of transient\ncore-level spectroscopies require a balanced treatment of both valence- and\ncore-electron excitations. To this end, tuned range-separated hybrid\nexchange-correlation functionals within the generalized Kohn-Sham scheme offer\na computationally efficient means of simultaneously improving the accuracy of\nvalence and core excitation energies in TDDFT by mitigating delocalization\nerrors across multiple length-scales. In this work range-separated hybrid\nfunctionals are employed in conjunction with the velocity-gauge formulation of\nreal-time TDDFT to simulate static as well as transient soft X-ray near-edge\nabsorption spectra in a prototypical solid-state system, monolayer hexagonal\nboron nitride, where excitonic effects are important. In the static case,\ncomputed soft X-ray absorption edge energies and line shapes are seen to be in\ngood agreement with experiment. Following laser excitation by a pump pulse,\nsoft X-ray probe spectra are shown to exhibit characteristic features of\npopulation induced bleaching and transient energy shifts of exciton peaks. The\nmethods outlined in this work therefore illustrate a practical means for\nsimulating attosecond time-resolved core-level spectra in solids within a TDDFT\nframework.",
        "positive": "Nanobubble-induced flow of immersed glassy polymer films: We study the free-surface deformation dynamics of an immersed glassy thin\npolymer film supported on a substrate, induced by an air nanobubble at the free\nsurface.We combine analytical and numerical treatments of the glassy thin film\nequation, resulting from the lubrication approximation applied to the surface\nmobile layer of the glassy film, under the driving of an axisymmetric step\nfunction in the pressure term accounting for the nanobubble's Laplace pressure.\nUsing the method of Green's functions, we derive a general solution for the\nfilm profile. We show that the lateral extent of the surface perturbation\nfollows an asymptotic viscocapillary power-law behaviour in time, and that the\nfilm's central height decays logarithmically in time in this regime. This\nprocess eventually leads to film rupture and dewetting at finite time, for\nwhich we provide an analytical prediction exhibiting explicitly the\ndependencies in surface mobility, film thickness and bubble size, among others.\nFinally, using finite-element numerical integration, we discuss how non-linear\neffects induced by the curvature and film profile can affect the evolution."
    },
    {
        "anchor": "Ternary Inorganic Electrides with mixed bonding: A high-throughput screening based on first-principles calculations was\nperformed to search for new ternary inorganic electrides. From the available\nmaterials database, we identified three new thermodynamically stable materials\n(Li$_{12}$Mg$_3$Si$_4$, NaBa$_2$O and Ca$_5$Ga$_2$N$_4$) as potential\nelectrides made by main group elements, in addition to the well known mayenite\nbased electride (C12A7:$e^-$). Different from those conventional inorganic\nelectrides in which the excess electrons play only the role of anions, the\nthree new materials, resembling the electrides found in simple metals under\nhigh pressure, possess mixed ionic and metallic bonding. The interplay between\ntwo competing mechanisms, together with the different crystal packing motifs,\ngives rise to a variety of geometries in anionic electrons, and rich physical\nphenomena such as ferromagnetism, superconductivity and metal-insulator\ntransition. Our finding here bridges the gap between electrides found at\nambient and high pressure conditions.",
        "positive": "Structural and Electronic Properties of a Carbon Nanotorus: Effects of\n  Delocalized Vs Localized Deformations: The bending of a carbon nanotube is studied by considering the structural\nevolution of a carbon nanotorus from elastic deformation to the onset of the\nkinks and eventually to the collapse of the walls of the nanotorus. The changes\nin the electronic properties due to {\\it non-local} deformation are contrasted\nwith those due to {\\it local} deformation to bring out the subtle issue\nunderlying the reason why there is only a relatively small reduction in the\nelectrical conductance in the former case even at large bending angles while\nthere is a dramatic reduction in the conductance in the latter case at\nrelatively small bending angles."
    },
    {
        "anchor": "Mapping the Structure of Oxygen-Doped Wurtzite Aluminum Nitride Coatings\n  From Ab Initio Random Structure Search and Experiments: Machine learning is changing how we design and interpret experiments in\nmaterials science. In this work, we show how unsupervised learning, combined\nwith ab initio modeling, improves our understanding of structural metastability\nin multicomponent alloys. We use the example case of Al-O-N alloys where the\nformation of aluminum vacancies in wurtzite AlN upon the incorporation of\nsubstitutional oxygen can be seen as a general mechanism of solids where\ncrystal symmetry is reduced to stabilize defects. The ideal AlN wurtzite\ncrystal structure occupation cannot be matched due to the presence of an\naliovalent hetero-element into the structure. The traditional interpretation of\nthe c-lattice shrinkage in sputter-deposited Al-O-N films from X-ray\ndiffraction (XRD) experiments suggests the existence of a solubility limit at\n8at.% oxygen content. Here we show that such naive interpretation is\nmisleading. We support XRD data with a machine learning analysis of ab initio\nsimulations and positron annihilation lifetime spectroscopy data, revealing no\nsigns of a possible solubility limit. Instead, the presence of a wide range of\nnon-equilibrium oxygen-rich defective structures emerging at increasing oxygen\ncontents suggests that the formation of grain boundaries is the most plausible\nmechanism responsible for the lattice shrinkage measured in Al-O-N sputtered\nfilms.",
        "positive": "Energy barriers for diffusion on stepped Rh(111) surfaces: Energy barriers for different moves of a single Rh adatom in the vicinity of\nsteps on Rh(111) surface are studied with molecular statics. Interatomic\ninteractions are modeled by the semi-empirical many-body\nRosato-Guillope-Legrand potential. We calculate systematically barriers for the\ndescent at straight steps, steps with the kink and small islands as well as\nbarriers for diffusion along the step edges. The descent is more probable on\nsteps with a {111} microfacet and near kinks. Diffusion along a step with a\n{100} microfacet is faster than along a step with a {111} microfacet. We also\ncalculate barriers for diffusion on several surfaces vicinal to Rh(111)."
    },
    {
        "anchor": "Stone-Wales Defects Preserve Hyperuniformity in Amorphous\n  Two-Dimensional Materials: Crystalline two-dimensional (2D) materials such as graphene possess unique\nphysical properties absent in their bulk form, enabling many novel device\napplications. Yet, little is known about their amorphous counterparts, which\ncan be obtained by introducing the Stone-Wales (SW) topological defects via\nproton radiation. Here we provide strong numerical evidence that SW defects\npreserve hyperuniformity in hexagonal 2D materials, a recently discovered new\nstate of matter characterized by vanishing normalized infinite-wavelength\ndensity fluctuations, which implies that all amorphous states of these\nmaterials are hyperuniform. Specifically, the static structure factor S(k) of\nthese materials possesses the scaling S(k) ~ k^{\\alpha} for small wave number\nk, where 1<=\\alpha(p)<=2 is monotonically decreasing as the SW defect\nconcentration p increases, indicating a transition from type-I to type-II\nhyperuniformity at p ~= 0.12 induced by the saturation of the SW defects. This\nhyperuniformity transition marks a structural transition from perturbed lattice\nstructures to truly amorphous structures, and underlies the onset of strong\ncorrelation among the SW defects as well as a transition between distinct\nelectronic transport mechanisms associated with different hyperuniformity\nclasses.",
        "positive": "On the Electride Nature of Na-hP4: Early quantum mechanical models suggested that pressure drives solids towards\nfree-electron metal behavior where the ions are locked into simple close-packed\nstructures. The prediction and subsequent discovery of high-pressure electrides\n(HPEs), compounds assuming open structures where the valence electrons are\nlocalized in interstitial voids, required a paradigm shift. Our quantum\nchemical calculations on the iconic insulating Na-hP4 HPE show that increasing\ndensity causes a 3s -> 3pd electronic transition due to Coulomb repulsion\nbetween the 1s2s and 3s states, and orthogonality of the 3pd states to the\ncore. The large lobes of the resulting Na-pd hybrid orbitals point towards the\ncenter of an 11-membered penta-capped trigonal prism and overlap\nconstructively, forming multi-centered bonds, which are responsible for the\nemergence of the interstitial charge localization in Na-hP4. These\nmulti-centered bonds facilitate the increased density of this phase, which is\nkey for its stabilization under pressure."
    },
    {
        "anchor": "Electronic Excitations and Correlation Effects in Metals: Theoretical descriptions of the spectrum of electronic excitations in real\nmetals have not yet reached a fully predictive, \"first-principles\" stage. In\nthis paper we begin by presenting brief highlights of recent progress made in\nthe evaluation of dynamical electronic response in metals. A comparison between\ncalculated and measured spectra - we use the loss spectra of Al and Cs as test\ncases - leads us to the conclusion that, even in \"weakly-correlated\" metals,\ncorrelation effects beyond mean-field theory play an important role.\nFurthermore, the effects of the underlying band structure turn out to be\nsignificant. Calculations which incorporate the effects of both dynamical\ncorrelations and band structure from first principles are not yet available. As\na first step towards such goal, we outline a numerical algorithm for the\nself-consistent solution of the Dyson equation for the one-particle Green's\nfunction. The self-energy is evaluated within the shielded-interaction\napproximation of Baym and Kadanoff. Our method, which is fully conserving, is a\nfinite-temperature scheme which determines the Green's function and the\nself-energy at the Matsubara frequencies on the imaginary axis. The analytical\ncontinuation to real frequencies is performed via Pade approximants. We present\nresults for the homogeneous electron gas which exemplify the importance of\nmany-body self-consistency.",
        "positive": "Carrier transport in layered nanolaminated films: Analyzing {\\it{ab-initio}} electronic and phonon band structure,\ntemperature-dependent carrier transport in layered Ti$_{2}$AlC is investigated.\nIt is found that cylindrical Fermi surface is the origin of the anisotropic\ncarrier effective mass (infinite effective mass along $c$ axis ) leading to\nstrong anisotropic (insulator along $c$ axis and metallic along the layer)\ncarrier transport in these films. Using electronic and phonon bandstructures,\nwe develop an analytical model of electron-phonon interaction as well as\nin-plane carrier conductivity originating from strong inter-valley\n(s$\\rightarrow$d) scattering in Ti$_{2}$AlC. We invoke density functional\ntheory to calculate the deformation potential corresponding to acoustic phonon\nvibration. The calculated deformation potential is in well agreement with the\nextracted deformation potential value from the transport data. Extracted\ndeformation potential will be useful for prediction of transport quantities for\napplication of these metals at elevated temperatures."
    },
    {
        "anchor": "$ \\mathrm{Sr}_{4}\\mathrm{Al}_{2}\\mathrm{O}_{7}$: A New Sacrificial Layer\n  with High Water Dissolution Rate for the Synthesis of Freestanding Oxide\n  Membranes: Freestanding perovskite oxide membranes have drawn great attention recently\nsince they offer exceptional structural tunability and stacking ability,\nproviding new opportunities in fundamental research and potential device\napplications in silicon-based semiconductor technology. Among different types\nof sacrificial layers, the $ \\mathrm{(Ca, Sr,\nBa)}_{3}\\mathrm{Al}_{2}\\mathrm{O}_{6}$ compounds are most widely used since\nthey can be dissolved in water and prepare high-quality perovskite oxide\nmembranes with clean and sharp surfaces and interfaces. However, the typical\ntransfer process takes a long time (up to hours) in obtaining millimeter-size\nfreestanding membranes, let alone realize wafer-scale samples with high yield.\nHere, we introduce a new member of the $\n\\mathrm{SrO-}\\mathrm{Al}_{2}\\mathrm{O}_{3}$ family,$\n\\mathrm{Sr}_{4}\\mathrm{Al}_{2}\\mathrm{O}_{7},$, and demonstrate its high\ndissolution rate, about 10 times higher than that of $\n\\mathrm{Sr}_{3}\\mathrm{Al}_{2}\\mathrm{O}_{6}$. The high-dissolution-rate of $\n\\mathrm{Sr}_{4}\\mathrm{Al}_{2}\\mathrm{O}_{7}$ is most likely related to the\nmore discrete Al-O networks and higher concentration of water-soluble Sr-O\nspecies in this compound. Our work significantly facilitates the preparation of\nfreestanding membranes and sheds light on the integration of multifunctional\nperovskite oxides in practical electronic devices.",
        "positive": "Time-lapsed graphene moir\u00e9 superlattice on Cu(111): The detailed study of the graphene (gr) moir\\'e superlattices emerging due to\nthe mismatch between the substrate's and gr-overlayer crystal lattices is\ninevitable because of its high technological relevance. However, little is\nknown about the dynamics of moir\\'e superstructures on gr. Here, we report the\nfirst classical molecular dynamics simulation (CMD) of the moir\\'e superlattice\nof graphene on Cu(111) using a new parameterized Tersoff-potential for the\ngraphene/Cu(111) interface fitted in this paper to nonlocal van der Waals\ndensity functional theory (DFT) calculations. The interfacial force field with\ntime-lapsed CMD provides superlattices in good quantitative agreement with the\navailable experimental results. The long range coincidence supercells of $2\n\\times 2$ and $3 \\times 3$ with nonequivalent moir\\'e hills have also been\nidentified and analyzed. The moir\\'e superlattice exhibits a pattern which is\ndynamical rather than statically pinned to the support and can be observed\nmostly via time lapsing. The instantaneous snapshots of the periodic moir\\'e\npattern already at low temperature are weakly disordered lacking the apparent\nsharpness of the time averaged pattern and scanning tunneling microscopy\nimages. This suggests the existence of competing orders between a static (1st\norder) and a dynamical (2nd order) moir\\'e superstructures.The revealed random\nheight fluctuations may limit the important electronic properties of supported\ngraphene such as the mobility of charge carriers."
    },
    {
        "anchor": "Molecular dynamics study of the effect of moisture and porosity on\n  thermal conductivity of tobermorite 14 \u00c5: The effect of moisture and porosity on thermal conductivity of tobermorite 14\n\\AA~as the major component of cement paste is studied by using molecular\ndynamics simulation with ClayFF potential. The calculated results show that the\nthermal conductivity increases monotonically as the moisture content by mass\nwithin the interior pores increases and the slope of the linear fitting\nfunction decreases as the porosity increases. Meanwhile, the normalized thermal\nconductivity is found to increase exponentially as increasing the moisture\ncontent by volume. Phonon density of states of porous and moist tobermorite 14\n\\AA~is used to explain the contribution of individual atoms and molecules to\nthe thermal properties. The results can be potentially used to design higher\nthermal insulating materials with cement and concrete for energy saving\nbuildings.",
        "positive": "Millimeter-scale freestanding superconducting infinite-layer nickelate\n  membranes: Progress in the study of infinite-layer nickelates has always been highly\nlinked to materials advances. In particular, the recent development of\nsuperconductivity via hole-doping was predicated on the controlled synthesis of\nNi in a very high oxidation state, and subsequent topotactic reduction to a\nvery low oxidation state, currently limited to epitaxial thin films. Here we\ndemonstrate a process to combine these steps with a heterostructure which\nincludes an epitaxial soluble buffer layer, enabling the release of\nfreestanding membranes of (Nd,Sr)NiO2 encapsulated in SrTiO3, which serves as a\nprotective layer. The membranes have comparable structural and electronic\nproperties to that of optimized thin films, and range in lateral dimensions\nfrom millimeters to ~100 micron fragments, depending on the degree of strain\nreleased with respect to the initial substrate. The changes in the\nsuperconducting transition temperature associated with membrane release are\nquite similar to those reported for substrate and pressure variations,\nsuggestive of a common underlying mechanism. These membranes structures should\nprovide a versatile platform for a range of experimental studies and devices\nfree from substrate constraints."
    },
    {
        "anchor": "Theoretical study of the stripline ferromagnetic resonance response of\n  metallic ferromagnetic films based on an analytical model: We develop an advanced analytical model for calculating the broadband\nstripline ferromagnetic resonance (FMR) response for metallic ferromagnetic\nfilms, taking into account the exchange interaction as well as the exchange\nboundary conditions at the film surface. This approach leads to simple\nanalytical expressions in the Fourier space. As a result, a numerical code\nwhich implements inverse Fourier transform of these equations is very quick.\nThis allows us to explore a wide space of parameters as numerical examples of\napplication of this theory. In particular, we investigate the joint effect of\nmicrowave eddy current shielding and magnetisation pinning at the ferromagnetic\nfilm surfaces on the shape of the stripline FMR response of the film.",
        "positive": "Phenomenological theory of a single domain wall in uniaxial trigonal\n  ferroelectrics: lithium niobate and lithium tantalate: A phenomenological treatment of domain walls based on the\nGinzburg-Landau-Devonshire theory is developed for uniaxial, trigonal\nferroelectrics lithium niobate and lithium tantalate. The contributions to the\ndomain wall energy from polarization and strain as a function of orientation\nare considered. Analytical expressions are developed which are analyzed\nnumerically to determine the minimum polarization, strain, and energy\nconfigurations of domain walls. It is found that hexagonal y-walls are\npreferred over x-walls in both materials. This agrees well with experimental\nobservation of domain geometries in stoichiometric composition crystals."
    },
    {
        "anchor": "Unconventional transport behavior in the Quaternary Heusler compounds\n  CoFeTiSn and CoFeVGa: We report here the electrical transport and magnetic properties of the newly\nsynthesized quaternary Heusler compound CoFeTiSn and CoFeVGa. We observe a\nstriking change in the electronic transport properties of CoFeTiSn as the\nsystem undergoes the paramagnetic to ferromagnetic transition. While the sample\nshows an activated semiconducting behaviour in the paramagnetic phase, it turns\nabruptly to a metallic phase with the onset of ferromagnetic transition. We\nhave compared the system with other Hesuler compounds showing similar anomaly\nin transport, and it appears that CoFeTiSn has much similarities with the\nFe$_2$VAl compound having pseudogap in the paramagnetic phase. In sharp\ncontrast, CoFeVGa shows a predominantly semiconducting behaviour down to 90 K,\nbelow which it shows a window of metallic region. Both the compositions show\nnegative Seebeck coefficient varying linearly with temperature. The value of\nthe Seebeck coefficient of CoFeTiSn is comparable to that of many Heusler\nalloys identified as potential thermoelectric materials.",
        "positive": "Tetragonal CuMnAs alloy: role of defects: The antiferromagnetic (AFM) CuMnAs alloy with tetragonal structure is a\npromising material for the AFM spintronics. The resistivity measurements\nindicate the presence of defects about whose types and concentrations is more\nspeculated as known. We confirmed vacancies on Mn or Cu sublattices and\nMn$_{\\rm Cu}$ and Cu$_{\\rm Mn}$ antisites as most probable defects in CuMnAs by\nour new ab initio total energy calculations. We have estimated resistivities of\npossible defect types as well as resistivities of samples for which the X-ray\nstructural analysis is available. In the latter case we have found that samples\nwith Cu- and Mn-vacancies with low formation energies have also resistivities\nwhich agree well with the experiment. Finally, we have also calculated exchange\ninteractions and estimated the N\\'eel temperatures by using the Monte Carlo\napproach. A good agreement with experiment was obtained."
    },
    {
        "anchor": "Direct observation of ordered configurations of hydrogen adatoms on\n  graphene: Ordered configurations of hydrogen adatoms on graphene have long been\nproposed, calculated and searched for. Here we report direct observation of\nseveral ordered configurations of H adatoms on graphene by scanning tunneling\nmicroscopy. On the top side of the graphene plane, H atoms in the\nconfigurations appear to stick to carbon atoms in the same sublattice. A gap\nlarger than 0.6 eV in the local density of states of the configurations was\nrevealed by scanning tunneling spectroscopy measurements. These findings can be\nwell explained by density functional theory calculations based on double sided\nH configurations. In addition, factors that may influence H ordering are\ndiscussed.",
        "positive": "Surface dipole of F4TCNQ films: Collective charge transfer and\n  dipole-dipole repulsion in submonolayers: A charge transfer (CT) model is introduced for strong acceptors like A =\nF4TCNQ that are ionized on surfaces at low coverage {\\theta}. Each A forms a CT\ndimer with a surface state S. Dipole-dipole repulsion grows as {\\theta}^(3/2)\nup to {\\theta} = 1 in a full monolayer. Electron transfer {\\rho}({\\theta})\nwithin dimers is found self-consistently and decreases with increasing\ncoverage. The surface dipole and work function shift {\\Delta}{\\Phi} are\nproportional to {\\theta}{\\rho}({\\theta}). The CT model has implications for\nphotoemission and accounts for {\\Delta}{\\Phi}(d) profiles of F4TCNQ films of\nthickness d on Cu(1,1,1) or on hydrogenated diamond (1,0,0). The CT model also\ndescribes {\\Delta}{\\Phi}({\\theta}) of organic donors on metals and is\ncontrasted to previous treatments of dipoles on a surface."
    },
    {
        "anchor": "Systematic Builder for All-Atom Simulations of Plastically Bonded\n  Explosives: The shock to detonation transition in heterogeneous plastically bonded\nexplosives is dominated by energy localization into hotspots that arise from\nthe interaction of the shockwave with microstructural features and defects. The\ncomplex polycrystalline structure of these materials leads to a network of\nhotspot that can coalesce into deflagration and detonation waves. Significant\nprogress has been made on the formation and potency of hotspots using atomistic\nsimulations, but most of the work has focused on ideal and isolated defects.\nHence, developed a method, denoted PBXGen, to build realistic PBX\nmicrostructures for all-atom simulations. PBXGen is generally applicable, and\nwe demonstrate it with two systems: an RDX-polystyrene PBX with a 3D\nmicrostructure and a TATB-polystyrene with columnar grains. The resulting\nstructure exhibit key features of PBXs, albeit at smaller scales, and are\nvalidated against experimental mechanical and shock properties.",
        "positive": "Enhanced spin-orbit torque via modulation of spin current absorption: The magnitude of spin-orbit torque (SOT), exerted to a ferromagnet (FM) from\nan adjacent heavy metal (HM), strongly depends on the amount of spin currents\nabsorbed in the FM. We exploit the large spin absorption at the Ru interface to\nmanipulate the SOTs in HM/FM/Ru multilayers. While the FM thickness is smaller\nthan its spin dephasing length of 1.2 nm, the top Ru layer largely boosts the\nabsorption of spin currents into the FM layer and substantially enhances the\nstrength of SOT acting on the FM. Spin-pumping experiments induced by\nferromagnetic resonance support our conclusions that the observed increase in\nthe SOT efficiency can be attributed to an enhancement of the spin-current\nabsorption. A theoretical model that considers both reflected and transmitted\nmixing conductances at the two interfaces of FM is developed to explain the\nresults."
    },
    {
        "anchor": "Dark Soliton Excitations in Single Wall Carbon Nanotubes: Dark soliton excitations are shown to exist in single wall carbon nanotubes\n(SWCNTs). At first, the nonlinear effective interatomic potential and the\ndifference equation for longitudinal lattice displacement are obtained for the\nSWCNTs by expanding Brenner's many-body potential in a Taylor series up to\nfourth-order terms. Then using a multi-scale method, for short wavelength\nlattice excitations the equation of motion of lattice is reduced to the cubic\nnonlinear Schrodinger equation. Finally, the dark soliton solutions and\nrelevant excitations in the SWCNTs with subsonic velocity are discussed.",
        "positive": "MatNexus: A Comprehensive Text Mining and Analysis Suite for Materials\n  Discover: MatNexus is a specialized software for the automated collection, processing,\nand analysis of text from scientific articles. Through an integrated suite of\nmodules, the MatNexus facilitates the retrieval of scientific articles,\nprocesses textual data for insights, generates vector representations suitable\nfor machine learning, and offers visualization capabilities for word\nembeddings. With the vast volume of scientific publications, MatNexus stands\nout as an end-to-end tool for researchers aiming to gain insights from\nscientific literature in material science, making the exploration of materials,\nsuch as the electrocatalyst examples we show here, efficient and insightful."
    },
    {
        "anchor": "Determination of acoustic phonon anharmonicities via second-order Raman\n  scattering in CuI: We demonstrate the determination of anharmonic acoustic phonon properties via\nsecond-order Raman scattering exemplarily on copper iodide single crystals. The\norigin of multi-phonon features from the second-order Raman spectra was\nassigned by the support of the calculated 2-phonon density of states. In this\nway, the temperature dependence of acoustic phonons was determined down to\n10\\,K. To determine independently the harmonic contributions of respective\nacoustic phonons, density functional theory (DFT) in quasi-harmonic\napproximation was used. Finally, the anharmonic contributions were determined.\nThe results are in agreement with earlier publications and extend CuI's\ndetermined acoustic phonon properties to lower temperatures with higher\naccuracy. This approach demonstrates that it is possible to characterize the\nacoustic anharmonicities via Raman scattering down to zero-temperature\nrenormalization constants of at least 0.1\\,cm$^{-1}$.",
        "positive": "Competing orders in PZN-xPT and PMN-xPT relaxor ferroelectrics: Neutron and x-ray scattering studies on relaxor ferroelectric systems\nPb(Zn$_{1/3}$Nb$_{2/3}$)O$_3$ (PZN), Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_3$ (PMN), and\ntheir solid solutions with PbTiO$_3$ (PT) have shown that inhomogeneities and\ndisorder play important roles in the materials properties. Although a\nlong-range polar order can be established at low temperature - sometimes with\nthe help of an external electric field; short-range local structures called the\n``polar nano-regions'' (PNR) still persist. Both the bulk structure and the PNR\nhave been studied in details. The coexistence and competition of long- and\nshort-range polar orders and how they affect the structural and dynamical\nproperties of relaxor materials are discussed."
    },
    {
        "anchor": "DFT+U and Quantum Monte Carlo study of electronic and optical properties\n  of AgNiO$_2$ and AgNi$_{1-x}$Co$_{x}$O$_2$ delafossite: As the only semimetallic $d^{10}$-based delafossite, AgNiO$_2$ has received a\ngreat deal of attention due to both its unique semimetallicity and its\nantiferromagnetism in the NiO$_2$ layer that is coupled with a lattice\ndistortion. In contrast, other delafossites such as AgCoO$_2$ are insulating.\nHere we study how the electronic structure of AgNi$_{1-x}$Co$_{x}$O$_2$ alloys\nvary with Ni/Co concentration, in order to investigate the electronic\nproperties and phase stability of the intermetallics. While the electronic and\nmagnetic structure of delafossites have been studied using Density Functional\nTheory (DFT), earlier studies have not included corrections for strong on-site\nCoulomb interactions. In order to treat these interactions accurately, in this\nstudy we use Quantum Monte Carlo (QMC) simulations to obtain accurate estimates\nfor the electronic and magnetic properties of AgNiO$_2$. By comparison to DFT\nresults we show that these electron correlations are critical to account for.\nWe show that Co doping on the magnetic Ni sites results in a metal-insulator\ntransition near $x\\sim 0.33$, and reentrant behavior near $x\\sim 0.66$",
        "positive": "Pseudo Spin Valves Using a (112)-textured DO_22 MnGa Fixed Layer: We demonstrate pseudo spin valves with a (112)-textured DO_22 MnGa (MnGa)\ntilted magnetization fixed layer and an in-plane CoFe free layer. Single D0_22\nMnGa films exhibit a small magnetoresistance (MR) typically observed in metals.\nIn MnGa/Cu/ CoFe spin valves a transition from a negative (-0.08%) to positive\n(3.88%) MR is realized by introducing a thin spin polarizing CoFe insertion\nlayer at the MnGa/Cu interface and tailoring the MnGa thickness. Finally, the\nexchange coupling between the MnGa and CoFe insertion layer is studied using a\nfirst-order reversal curve (FORC) technique."
    },
    {
        "anchor": "Neural networks trained on synthetically generated crystals can extract\n  structural information from ICSD powder X-ray diffractograms: Machine learning techniques have successfully been used to extract structural\ninformation such as the crystal space group from powder X-ray diffractograms.\nHowever, training directly on simulated diffractograms from databases such as\nthe ICSD is challenging due to its limited size, class-inhomogeneity, and bias\ntoward certain structure types. We propose an alternative approach of\ngenerating synthetic crystals with random coordinates by using the symmetry\noperations of each space group. Based on this approach, we demonstrate online\ntraining of deep ResNet-like models on up to a few million unique on-the-fly\ngenerated synthetic diffractograms per hour. For our chosen task of space group\nclassification, we achieved a test accuracy of 79.9% on unseen ICSD structure\ntypes from most space groups. This surpasses the 56.1% accuracy of the current\nstate-of-the-art approach of training on ICSD crystals directly. Our results\ndemonstrate that synthetically generated crystals can be used to extract\nstructural information from ICSD powder diffractograms, which makes it possible\nto apply very large state-of-the-art machine learning models in the area of\npowder X-ray diffraction. We further show first steps toward applying our\nmethodology to experimental data, where automated XRD data analysis is crucial,\nespecially in high-throughput settings. While we focused on the prediction of\nthe space group, our approach has the potential to be extended to related tasks\nin the future.",
        "positive": "Size distribution of sputtered particles from Au nanoislands due to MeV\n  self-ion bombardment: Nanoisland gold films, deposited by vacuum evaporation of gold onto Si(100)\nsubstrates, were irradiated with 1.5 MeV Au$^{2+}$ ions up to a fluence of\n$5\\times 10^{14}$ ions cm$^{-2}$ and at incidence angles up to $60^{\\circ}$\nwith respect to the surface normal. The sputtered particles were collected on\ncarbon coated grids (catcher grid) during ion irradiation and were analyzed\nwith transmission electron microscopy and Rutherford backscattering\nspectrometry. The average sputtered particle size and the areal coverage are\ndetermined from transmission electron microscopy measurements, whereas the\namount of gold on the substrate is found by Rutherford backscattering\nspectrometry. The size distributions of larger particles (number of\natoms/particle, $n$ $\\ge$ 1,000) show an inverse power-law with an exponent of\n$\\sim$ -1 in broad agreement with a molecular dynamics simulation of ion impact\non cluster targets."
    },
    {
        "anchor": "Space-charge mechanism of aging in ferroelectrics: an exactly solvable\n  two-dimensional model: A mechanism of point defect migration triggered by local depolarization\nfields is shown to explain some still inexplicable features of aging in\nacceptor doped ferroelectrics. A drift-diffusion model of the coupled charged\ndefect transport and electrostatic field relaxation within a two-dimensional\ndomain configuration is treated numerically and analytically. Numerical results\nare given for the emerging internal bias field of about 1 kV/mm which levels\noff at dopant concentrations well below 1 mol%; the fact, long ago known\nexperimentally but still not explained. For higher defect concentrations a\nclosed solution of the model equations in the drift approximation as well as an\nexplicit formula for the internal bias field is derived revealing the plausible\ntime, temperature and concentration dependencies of aging. The results are\ncompared to those due to the mechanism of orientational reordering of defect\ndipoles.",
        "positive": "Magnetic microstructure and magnetotransport in Co2FeAl Heusler compound\n  thin films: We correlate simultaneously recorded magnetotransport and spatially resolved\nmagneto optical Kerr effect (MOKE) data in Co2FeAl Heusler compound thin films\nmicropatterned into Hall bars. Room temperature MOKE images reveal the\nnucleation and propagation of domains in an externally applied magnetic field\nand are used to extract a macrospin corresponding to the mean magnetization\ndirection in the Hall bar. The anisotropic magnetoresistance calculated using\nthis macrospin is in excellent agreement with magnetoresistance measurements.\nThis suggests that the magnetotransport in Heusler compounds can be adequately\nsimulated using simple macrospin models, while the magnetoresistance\ncontribution due to domain walls is of negligible importance."
    },
    {
        "anchor": "Interpretable discovery of new semiconductors with machine learning: Machine learning models of materials$^{1-5}$ accelerate discovery compared to\nab initio methods: deep learning models now reproduce density functional theory\n(DFT)-calculated results at one hundred thousandths of the cost of DFT$^{6}$.\nTo provide guidance in experimental materials synthesis, these need to be\ncoupled with an accurate yet effective search algorithm and training data\nconsistent with experimental observations. Here we report an evolutionary\nalgorithm powered search which uses machine-learned surrogate models trained on\nhigh-throughput hybrid functional DFT data benchmarked against experimental\nbandgaps: Deep Adaptive Regressive Weighted Intelligent Network (DARWIN). The\nstrategy enables efficient search over the materials space of ~10$^8$ ternaries\nand 10$^{11}$ quaternaries$^{7}$ for candidates with target properties. It\nprovides interpretable design rules, such as our finding that the difference in\nthe electronegativity between the halide and B-site cation being a strong\npredictor of ternary structural stability. As an example, when we seek UV\nemission, DARWIN predicts K$_2$CuX$_3$ (X = Cl, Br) as a promising materials\nfamily, based on its electronegativity difference. We synthesized and found\nthese materials to be stable, direct bandgap UV emitters. The approach also\nallows knowledge distillation for use by humans.",
        "positive": "Material design with the van der Waals stacking of bismuth-halide chains\n  realizing a higher-order topological insulator: The van der Waals (vdW) materials with low dimensions have been extensively\nstudied as a platform to generate exotic quantum properties. Advancing this\nview, a great deal of attention is currently paid to topological quantum\nmaterials with vdW structures. Here, we provide a new concept of designing\ntopological materials by the vdW stacking of quantum spin Hall insulators\n(QSHIs). Most interestingly, a slight shift of inversion center in the unit\ncell caused by a modification of stacking is found to induce the topological\nvariation from a trivial insulator to a higher-order topological insulator\n(HOTI). Based on that, we present the first experimental realization of a HOTI\nby investigating a bismuth bromide Bi4Br4 with angle-resolved photoemission\nspectroscopy (ARPES). The unique feature in bismuth halides capable of\nselecting various topology only by differently stacking chains, combined with\nthe great advantage of the vdW structure, offers a fascinating playground for\nengineering topologically non-trivial edge-states toward future spintronics\napplications."
    },
    {
        "anchor": "Charge-transfer induced large nonlinear optical properties of small Al\n  Clusters: Al4M4: We investigate the linear and nonlinear electric polarizabilities of small\nAl4M4 (M=Li, Na and K) clusters. Quantum chemical calculations reveal that\nthese compounds exhibit an exceptionally high magnitude of linear and nonlinear\noptical (NLO) coefficients which are orders of magnitude higher than the\nconventional pi-conjugated systems of similar sizes. We attribute such\nphenomenal increase to non-centrosymmetricity incorporated in the systems by\nthe alkali atoms surrounding the ring leading to charge transfer with small\noptical gap and low bond length alternation (BLA). Such a low magnitude of the\nBLA from a different origin, suggests the possibility that these clusters are\naromatic in character and along with the large NLO coefficients they appear to\nbe better candidates for next generation NLO fabrication devices.",
        "positive": "Seebeck coefficient of liquid water from equilibrium molecular dynamics: The application of a temperature gradient to an extended system generates an\nelectromotive force that induces an electric current in conductors and a\nmacroscopic polarization in insulators. The ratio of the electromotive force to\nthe temperature difference, usually referred to as the Seebeck coefficient, is\noften computed using non-equilibrium techniques, such as non-equilibrium\nmolecular dynamics (NEMD). In this paper we argue that thermo-polarization\neffects in insulating fluids can be conveniently treated by standard\nequilibrium thermodynamics and devise a protocol, based on a combination of\nequilibrium molecular dynamics and Bayesian inference methods, that allows one\nto compute the Seebeck coefficient in these systems along with a rigorous\nestimate of the resulting statistical accuracy. The application of our\nmethodology to liquid SPC/E water results in good agreement with previous\nstudies, based on more elaborate NEMD simulations, and in a more reliable\nestimate of the statistical accuracy of the results."
    },
    {
        "anchor": "The Band-Gap Problem in Semiconductors Revisited: Effects of Core States\n  and Many-Body Self-Consistency: A novel picture of the quasiparticle (QP) gap in prototype semiconductors Si\nand Ge emerges from an analysis based on all-electron, self-consistent, GW\ncalculations. The deep-core electrons are shown to play a key role via the\nexchange diagram --if this effect is neglected, Si becomes a semimetal.\nContrary to current lore, the Ge 3d semicore states (e.g., their polarization)\nhave no impact on the GW gap. Self-consistency improves the calculated gaps --a\nfirst clear-cut success story for the Baym-Kadanoff method in the study of\nreal-materials spectroscopy; it also has a significant impact on the QP\nlifetimes. Our results embody a new paradigm for ab initio QP theory.",
        "positive": "Experimental observation of spin glass state in highly disordered\n  quaternary Heusler alloy FeRuMnGa: The realization of spin-glass (S-G) state in Heusler alloys is very rare\ndespite the presence of inherent structural and elemental disorder in those\ncompounds. Although a few half and full Heusler alloys are known to exhibit S-G\nstate, there is hardly any manifestation of the same in cases of quaternary\nHeusler compounds. Here we report the observation of S-G state in a highly\ndisordered equiatomic quaternary Heusler compound: FeRuMnGa, where the S-G\nstate is in between of canonical S-G and cluster glass. Different intricate\nfeatures of S-G state including non-equilibrium magnetic dynamics at low\ntemperature in the compound are unveiled through our comprehensive magnetic,\nheat capacity and neutron diffraction studies. The structural disorder in the\nsample is neither conventional \\textit{A2}- nor \\textit{B2}-type while those\ntwo types are commonly observed for Heusler compounds. The presence of disorder\nalso plays a significant role in electron transport properties of the alloy,\nwhich is reflected in its exhibition of semi-metallic behavior and anomalous\nHall effect at low temperature."
    },
    {
        "anchor": "eXtended Variational Quasicontinuum Methodology for Lattice Networks\n  with Damage and Crack Propagation: Lattice networks with dissipative interactions are often employed to analyze\nmaterials with discrete micro- or meso-structures, or for a description of\nheterogeneous materials which can be modelled discretely. They are, however,\ncomputationally prohibitive for engineering-scale applications. The\n(variational) QuasiContinuum (QC) method is a concurrent multiscale approach\nthat reduces their computational cost by fully resolving the (dissipative)\nlattice network in small regions of interest while coarsening elsewhere. When\napplied to damageable lattices, moving crack tips can be captured by adaptive\nmesh refinement schemes, whereas fully-resolved trails in crack wakes can be\nremoved by mesh coarsening. In order to address crack propagation efficiently\nand accurately, we develop in this contribution the necessary generalizations\nof the variational QC methodology. First, a suitable definition of crack paths\nin discrete systems is introduced, which allows for their geometrical\nrepresentation in terms of the signed distance function. Second, special\nfunction enrichments based on the partition of unity concept are adopted, in\norder to capture kinematics in the wakes of crack tips. Third, a summation rule\nthat reflects the adopted enrichment functions with sufficient degree of\naccuracy is developed. Finally, as our standpoint is variational, we discuss\nimplications of the mesh refinement and coarsening from an energy-consistency\npoint of view. All theoretical considerations are demonstrated using two\nnumerical examples for which the resulting reaction forces, energy evolutions,\nand crack paths are compared to those of the direct numerical simulations.",
        "positive": "Microstructure from ferroelastic transitions using strain pseudospin\n  clock models in two and three dimensions: a local mean-field analysis: We show how microstructure can arise in first-order ferroelastic structural\ntransitions, in two and three spatial dimensions, through a local meanfield\napproximation of their pseudospin hamiltonians, that include anisotropic\nelastic interactions. Such transitions have symmetry-selected physical strains\nas their $N_{OP}$-component order parameters, with Landau free energies that\nhave a single zero-strain 'austenite' minimum at high temperatures, and\nspontaneous-strain 'martensite' minima of $N_V$ structural variants at low\ntemperatures. In a reduced description, the strains at Landau minima induce\ntemperature-dependent, clock-like $\\mathbb{Z}_{N_V +1}$ hamiltonians, with\n$N_{OP}$-component strain-pseudospin vectors ${\\vec S}$ pointing to $N_V + 1$\ndiscrete values (including zero). We study elastic texturing in five such\nfirst-order structural transitions through a local meanfield approximation of\ntheir pseudospin hamiltonians, that include the powerlaw interactions. As a\nprototype, we consider the two-variant square/rectangle transition, with a\none-component, pseudospin taking $N_V +1 =3$ values of $S= 0, \\pm 1$, as in a\ngeneralized Blume-Capel model. We then consider transitions with two-component\n($N_{OP} = 2$) pseudospins: the equilateral to centred-rectangle ($N_V =3$);\nthe square to oblique polygon ($N_V =4$); the triangle to oblique ($N_V =6$)\ntransitions; and finally the 3D cubic to tetragonal transition ($ N_V =3$). The\nlocal meanfield solutions in 2D and 3D yield oriented domain-walls patterns as\nfrom continuous-variable strain dynamics, showing the discrete-variable models\ncapture the essential ferroelastic texturings. Other related hamiltonians\nillustrate that structural-transitions in materials science can be the source\nof interesting spin models in statistical mechanics."
    },
    {
        "anchor": "Co-induced nano-structures on Si(111) surface: The interaction of cobalt atoms with silicon (111) surface has been\ninvestigated by means of scanning tunneling microscopy (STM) and low-energy\nelectron diffraction (LEED). Besides the Co silicide islands, we have\nsuccessfully distinguished two inequivalent Co-induced\n$\\sqrt{13}\\times\\sqrt{13}$ reconstructions on Si (111) surface. Our\nhigh-resolution STM images provide some structural properties of the two\ndifferent $\\sqrt{13}\\times\\sqrt{13}$ derived phases. Both of the two phases\nseem to form islands with single domain. The new findings will help us to\nunderstand the early stage of Co silicide formations.",
        "positive": "Non-contact method for measurement of the microwave conductivity of\n  graphene: We report a non-contact method for conductivity and sheet resistance\nmeasurements of graphene samples using a high Q microwave dielectric resonator\nperturbation technique, with the aim of fast and accurate measurement of\nmicrowave conductivity and sheet resistance of monolayer and few layers\ngraphene samples. The dynamic range of the microwave conductivity measurements\nmakes this technique sensitive to a wide variety of imperfections and\nimpurities and can provide a rapid non-contacting characterisation method.\nTypically the graphene samples are supported on a low-loss dielectric\nsubstrate, such as quartz, sapphire or SiC. This substrate is suspended in the\nnear-field region of a small high Q sapphire puck microwave resonator. The\npresence of the graphene perturbs both centre frequency and Q value of the\nmicrowave resonator. The measured data may be interpreted in terms of the real\nand imaginary components of the permittivity, and by calculation, the\nconductivity and sheet resistance of the graphene. The method has great\nsensitivity and dynamic range. Results are reported for graphene samples grown\nby three different methods: reduced graphene oxide (GO), chemical vapour\ndeposition (CVD) and graphene grown epitaxially on SiC. The latter method\nproduces much higher conductivity values than the others."
    },
    {
        "anchor": "Optical measurement of heteronuclear cross-relaxation interactions in\n  Tm:YAG: We investigate cross-relaxation interactions between Tm and Al in Tm:YAG\nusing two optical methods: spectral holeburning and stimulated echoes. These\ninteractions lead to a reduction in the hyperfine lifetime at magnetic fields\nthat bring the Tm hyperfine transition into resonance with an Al transition. We\ndevelop models for measured echo decay curves and holeburning spectra near a\nresonance, which are used to show that the Tm-Al interaction has a resonance\nwidth of 10~kHz and reduces the hyperfine lifetime to 0.5 ms. The antihole\nstructure is consistent with an interaction dominated by the Al nearest\nneighbors at 3.0 Angstroms, with some contribution from the next nearest\nneighbors at 3.6 Angstroms.",
        "positive": "Selective hydrogenation improves interface properties of high-k\n  dielectrics on 2D semiconductors: The integration of high-k dielectrics with two-dimensional (2D)\nsemiconductors is a critical step towards high-performance nanoelectronics,\nwhich however remains challenging due to high density of interface states and\nthe damage to the monolayer 2D semiconductors. In this study, we propose a\nselective hydrogenation strategy to improve the interface properties while do\nnot affect the 2D semiconductors. Using the interface of monolayer MoS2 and\nsilicon nitride as an example, we show substantially improved interface\nproperties for electronic applications after the interfacial hydrogenation, as\nevidenced by reduced inhomogeneous charge redistribution, increased band\noffset, and untouched electronic properties of MoS2. Interestingly, this\nhydrogenation process selectively occurs only at the silicon nitride surface\nand is compatible with the current semiconductor fabrication process. We\nfurther show that this strategy is general and applicable to other interfaces\nbetween high-k dielectrics and 2D semiconductors such as HfO2 on the monolayer\nMoS2. Our results demonstrate a simple yet viable way to improve the\ninterfacial properties for integrating many high-k dielectrics on a broad range\nof two-dimensional transition metal disulfide semiconductors."
    },
    {
        "anchor": "Orbital dependent electron tunneling within the atom superposition\n  approach: Theory and application to W(110): We introduce an orbital dependent electron tunneling model and implement it\nwithin the atom superposition approach for simulating scanning tunneling\nmicroscopy (STM) and spectroscopy (STS). Applying our method, we analyze the\nconvergence and the orbital contributions to the tunneling current and the\ncorrugation of constant current STM images above the W(110) surface. In\naccordance with a previous study [Heinze et al., Phys. Rev. B 58, 16432\n(1998)], we find atomic contrast reversal depending on the bias voltage.\nAdditionally, we analyze this effect depending on the tip-sample distance using\ndifferent tip models, and find two qualitatively different behaviors based on\nthe tip orbital composition. As an explanation, we highlight the role of the\nreal space shape of the orbitals involved in the tunneling. STM images\ncalculated by our model agree well with Tersoff-Hamann and Bardeen results. The\ncomputational efficiency of our model is remarkable as the k-point samplings of\nthe surface and tip Brillouin zones do not affect the computation time, in\ncontrast to the Bardeen method.",
        "positive": "Preparation of atomically-flat SrTiO3 surfaces using a deionized-water\n  etching and thermal annealing procedure: We report that a deionized water etching and thermal annealing technique can\nbe effective for preparing atomically-flat and singly-terminated surfaces of\nsingle crystalline SrTiO3 substrates. After a two-step thermal-annealing and\ndeionized-water etching procedure, topography measured by atomic force\nmicroscopy shows the evolution of substrates from a rough to step-terraced\nsurface structure. Lateral force microscopy confirms that the atomically-flat\nsurfaces are singly-terminated. Moreover, this technique can be used to remove\nexcessive strontium oxide or hydroxide composites segregated on the SrTiO3\nsurface. This acid-etchant-free technique facilitates the preparation of\natomically-aligned SrTiO3 substrates, which promotes studies on two-dimensional\nphysics of complex oxide interfaces."
    },
    {
        "anchor": "Quantum-size effect and tunneling magnetoresistance in\n  ferromagnetic-semiconductor quantum heterostructures: We report on the resonant tunneling effect and the increase of tunneling\nmagnetoresistance (TMR) induced by it in ferromagnetic-semiconductor GaMnAs\nquantum-well heterostructures. The observed quantum levels of the GaMnAs\nquantum well were successfully explained by the valence-band kp model with the\np-d exchange interaction. It was also found that the Fermi level of the\nelectrode injecting carriers is important to observe resonant tunneling in this\nsystem.",
        "positive": "Photoluminescence and Electron Spin Resonance of Silicon Dioxide Crystal\n  with Rutile Structure (Stishovite): An electron spin resonance (ESR) and photoluminescence signal is observed in\nthe as grown single crystal of stishovite indicating the presence of defects in\nthe non-irradiated sample. Photoluminescence of the as received stishovite\nsingle crystals exhibits two main bands - a blue at 3 eV and an UV at 4.75 eV.\nLuminescence is excited in the range of optical transparency of stishovite\n(below 8.75 eV) and, therefore, is ascribed to defects. A wide range of decay\nkinetics under a pulsed excitation is observed. For the blue band besides the\nexponential decay with a time constant of about 18 {\\mu}s an additional ms\ncomponent is revealed. For the UV band besides the fast component with a time\nconstant of 1-3 ns a component with a decay in tens {\\mu}s is obtained. The\nmain components (18 {\\mu}s and 1-3 ns) possess a typical intra-center\ntransition intensity thermal quenching. The effect of the additional slow\ncomponent is related to the presence of OH groups and/or carbon molecular\ndefects modifying the luminescence center. The additional slow components\nexhibit wave-like thermal dependences. Photo-thermally stimulated\ncreation-destruction of complex comprising host defect - interstitial modifiers\nexplains slow luminescence wave-like thermal dependences."
    },
    {
        "anchor": "Long period helical structures and twist-grain boundary phases induced\n  by non magnetic ion doping in Mn$_{1-x}$(Co,Rh)$_{x}$Ge chiral magnet: We study the evolution of helical magnetism in MnGe chiral magnet upon\npartial substitution of Mn for non magnetic 3d-Co and 4d-Rh ions. At high\ndoping levels, we observe spin helices with very long periods -more than ten\ntimes larger than in the pure compound- and sizable ordered moments. This\nbehavior calls for a change in the energy balance of interactions leading to\nthe stabilization of the observed magnetic structures. Strikingly, neutron\nscattering unambiguously shows a double periodicity in the observed spectra at\n$x \\gtrsim 0.45$ and $\\gtrsim 0.25$ for Co- and Rh-doping, respectively. In\nanalogy with observations made in cholesteric liquid crystals, we suggest that\nit reveals the presence of magnetic twist-grain-boundary phases, involving a\ndense short-range correlated network of screw dislocations. The dislocation\ncores are described as smooth textures made of non-radial double-core\nskyrmions.",
        "positive": "Theory of bilinear magneto-electric resistance from\n  topological-insulator surface states: We theoretically investigate a new kind of nonlinear magnetoresistance on the\nsurface of three-dimensional topological insulators (TIs). At variance with the\nunidirectional magnetoresistance (UMR) effect in magnetic bilayers, this\nnonlinear magnetoresistance does not rely on a conducting ferromagnetic layer\nand scales linearly with both the applied electric and magnetic fields; for\nthis reason, we name it bilinear magneto-electric resistance (BMER). We show\nthat the sign and the magnitude of the BMER depends sensitively on the\norientation of the current with respect to the magnetic field as well as the\ncrystallographic axes -- a property that can be utilized to map out the spin\ntexture of the topological surface states via simple transport measurement,\nalternative to the angle-resolved photoemission spectroscopy (ARPES)."
    },
    {
        "anchor": "Phase-field modelling of failure in ceramics with multiscale porosity: Many stiff biological materials exhibiting outstanding compressive\nstrength/weight ratio are characterized by high porosity, spanning different\nsize-scales, typical examples being bone and wood. A successful bio-mimicking\nof these materials is provided by a recently-obtained apatite, directly\nproduced through a biomorphic transformation of natural wood and thus\ninheriting its highly hierarchical structure. This unique apatite (but also\nwood and bone) is characterized by two major distinct populations of\ndifferently-sized cylindrical voids, a porosity shown in the present paper to\ninfluence failure, both in terms of damage growth and fracture nucleation and\npropagation. This statement follows from failure analysis, developed through\nin-silico generation of artificial samples (reproducing the two-scale porosity\nof the material) and subsequent finite element modelling of damage, implemented\nwith phase-field treatment for fracture growth. It is found that small voids\npromote damage nucleation and enhance bridging of macro-pores by micro-crack\nformation, while macro-pores influence the overall material response and drive\nthe propagation of large fractures. Our results explain the important role of\nmultiscale porosity characterizing stiff biological materials and lead to a new\ndesign paradigm, by introducing an in-silico tool to implement bio-mimicking in\nnew artificial materials with brittle behaviour, such as carbide or ceramic\nfoams.",
        "positive": "Magnetization and spin dynamics of a Cr-based magnetic cluster:\n  Cr$_{7}$Ni: We study the magnetization and the spin dynamics of the Cr$_7$Ni ring-shaped\nmagnetic cluster. Measurements of the magnetization at high pulsed fields and\nlow temperature are compared to calculations and show that the spin Hamiltonian\napproach provides a good description of Cr$_7$Ni magnetic molecule. In\naddition, the phonon-induced relaxation dynamics of molecular observables has\nbeen investigated. By assuming the spin-phonon coupling to take place through\nthe modulation of the local crystal fields, it is possible to evaluate the\ndecay of fluctuations of two generic molecular observables. The nuclear\nspin-lattice relaxation rate $1/T_1$ directly probes such fluctuations, and\nallows to determine the magnetoelastic coupling strength."
    },
    {
        "anchor": "Electronic properties of metal-induced gap states formed at\n  alkali-halide/metal interfaces: The spatial distribution and site- distribution of metal induced gap states\n(MIGS) are studied by thickness dependent near edge x-ray absorption fine\nstructure (NEXAFS) and comparing the cation and anion edge NEXAFS. The\nthickness dependent NEXAFS shows that the decay length of MIGS depends on\nrather an alkali halide than a metal, and it is larger for alkali halides with\nsmaller band gap energy. By comparing the Cl edge and K edge NEXAFS for\nKCl/Cu(001), MIGS are found to be states localizing at anion sites.",
        "positive": "Electrostatic carrier doping of GdTiO3/SrTiO3 interfaces: Heterostructures and superlattices consisting of a prototype Mott insulator,\nGdTiO3, and the band insulator SrTiO3 are grown by molecular beam epitaxy and\nshow intrinsic electronic reconstruction, approximately 1/2 electron per\nsurface unit cell at each GdTiO3/SrTiO3 interface. The sheet carrier densities\nin all structures containing more than one unit cell of SrTiO3 are independent\nof layer thicknesses and growth sequences, indicating that the mobile carriers\nare in a high concentration, two-dimensional electron gas bound to the\ninterface. These carrier densities closely meet the electrostatic requirements\nfor compensating the fixed charge at these polar interfaces. Based on the\nexperimental results, insights into interfacial band alignments, charge\ndistribution and the influence of different electrostatic boundary conditions\nare obtained."
    },
    {
        "anchor": "Thickness-dependent Characteristics and Oxidation of Cadmium: In this study, the structural, electronic and vibrational properties of\nthinnest possible Cadmium crystal are investigated by performing\nfirst-principle calculations. Total energy optimization and dynamic stability\ncalculations reveal that the thinnest possible crystal structure is a\ndouble-layered structure consisting of alternating layers formed by trigonal\narrangements of Cd atoms. Excessive softening of optical phonons occurs as a\nresult of structural relaxation when going from a bulk to a single layer (SL)\nstructure. It is also shown that thinnest structure obtained from bulk Cd\ncrystals maintains its metallic feature despite the dimensional crossover. In\naddition, it is predicted through calculations that the SL Cd crystal strongly\ninteracts with oxygen and that the oxidized regions even undergo chemical\ntransformation to form the CdO crystal. In the double-layer CdO crystal\nresulting from the oxidation of individual Cd layers, the layers are connected\nto each other with strong covalent bonds, and this structure is a semiconductor\nwith a band gap of 2.10 eV. While the robust metallic structure of the thinnest\npossible Cd crystal provides flexibility in terms of its use in nanoscale\napplications, on the other hand, the fact that its electronic properties can be\nchanged by oxidation is important for optoelectronic device applications.",
        "positive": "Exploring qubit-qubit entanglement mediated by one-dimensional plasmonic\n  nanowaveguides: We exploit the qubit-qubit coupling induced by plasmon-polariton modes in a\none-dimensional nanowaveguide to obtain various two-qubit entanglement\nsituations. Firstly, we observe three phenomena occurring when preparing the\ninitial state of the system and leaving it freely relax: spontaneous formation\nof entanglement, sudden birth and revival. Then, we show that plugging a laser\nto each of the qubit, the system arrives to an steady state which, depending on\ntheir inter-qubit distance, can also be entangled. For this situation, we also\ncharacterize the quantum state of the system showing the entanglement-purity-\ndiagram typical for two-qubit systems."
    },
    {
        "anchor": "Quantum Confinement of Electron-Phonon Coupling in Graphene Quantum Dots: On the basis of first-principles calculations and the special displacement\nmethod, we demonstrate the quantum confinement scaling law of the\nphonon-induced gap renormalization of graphene quantum dots (GQDs). We employ\nzigzag-edged GQDs with hydrogen passivation and embedded in hexagonal boron\nnitride. Our calculations for GQDs in the sub-10 nm region reveal strong\nquantum confinement of the zero-point renormalization ranging from 20 to 250\nmeV. To obtain these values we introduce a correction to the Allen-Heine theory\nof temperature-dependent energy levels that arises from the phonon-induced\nsplitting of 2-fold degenerate edge states. This correction amounts to more\nthan 50% of the gap renormalization. We also present momentum-resolved spectral\nfunctions of GQDs, which are not reported in previous contributions. Our\nresults lay the foundation to systematically engineer temperature-dependent\nelectronic structures of GQDs for applications in solar cells, electronic\ntransport, and quantum computing devices.",
        "positive": "A micropolar continuum model of diffusion creep: Solid polycrystalline materials undergoing diffusion creep are usually\ndescribed by Cauchy continuum models with a Newtonian viscous rheology\ndependent on the grain size. Such a continuum lacks the rotational degrees of\nfreedom needed to describe grain rotation. Here we provide a more general\ncontinuum description of diffusion creep that includes grain rotation, and\nidentifies the deformation of the material with that of a micropolar (Cosserat)\nfluid. We derive expressions for the micropolar constitutive tensors by a\nhomogenisation of the physics describing a discrete collection of rigid grains,\ndemanding an equivalent dissipation between the discrete and continuum\ndescriptions. General constitutive laws are derived for both Coble\n(grain-boundary diffusion) and Nabarro-Herring (volume diffusion) creep.\nDetailed calculations are performed for a two-dimensional tiling of irregular\nhexagonal grains, which illustrates a potential coupling between the rotational\nand translational degrees of freedom. If only the plating out or removal of\nmaterial at grain boundaries is considered, the constitutive laws are\ndegenerate: modes of deformation that involve pure tangential motion at the\ngrain boundaries are not resisted. This degeneracy can be removed by including\nthe resistance to grain-boundary sliding, or by imposing additional constraints\non the deformation."
    },
    {
        "anchor": "Hybrid functional study of proper and improper multiferroics: We present a detailed study of the structural, electronic, magnetic and\nferroelectric properties of prototypical \\textit{proper} and \\textit{improper}\nmultiferroic (MF) systems such as BiFeO$_{3}$ and orthorhombic HoMnO$_{3}$,\nrespectively, within density functional theory (DFT) and using the\nHeyd-Scuseria-Ernzerhof hybrid functional (HSE). By comparing our results with\navailable experimental data as well as with state-of-the-art GW calculations,\nwe show that the HSE formalism is able to account well for the relevant\nproperties of these compounds and it emerges as an accurate tool for predictive\nfirst-principles investigations on multiferroic systems. We show that effects\nbeyond local and semilocal DFT approaches (as provided by HSE) are necessary\nfor a realistic description of MFs. For the electric polarization, a decrease\nis found for MFs with magnetically-induced ferroelectricity, such as HoMnO$_3$,\nwhere the calculated polarization changes from $\\sim$ 6 $\\mu C/cm^2$ using\nPerdew-Burke-Ernzerhof (PBE) to $\\sim$ 2 $\\mu C/cm^2$ using HSE. However, for\n\\textit{proper} MFs, such as BiFeO$_{3}$, the polarization slightly increases\nupon introduction of exact exchange. Our findings therefore suggest that a\ngeneral trend for the HSE correction to bare density functional cannot be\nextracted; rather, a specific investigation has to be carried out on each\ncompound.",
        "positive": "Formation of Nanotwin Networks during High-Temperature Crystallization\n  of Amorphous Germanium: Germanium is an extremely important material used for numerous functional\napplications in many fields of nanotechnology. In this paper, we study the\ncrystallization of amorphous Ge using atomistic simulations of critical\nnano-metric nuclei at high temperatures. We find that crystallization occurs by\nthe recurrent transfer of atoms via a diffusive process from the amorphous\nphase into suitably-oriented crystalline layers. We accompany our simulations\nwith a comprehensive thermodynamic and kinetic analysis of the growth process,\nwhich explains the energy balance and the interfacial growth velocities\ngoverning grain growth. For the $\\langle111\\rangle$ crystallographic\norientation, we find a degenerate atomic rearrangement process, with two\nzero-energy modes corresponding to a perfect crystalline structure and the\nformation of a $\\Sigma3$ twin boundary. Continued growth in this direction\nresults in the development a twin network, in contrast with all other growth\norientations, where the crystal grows defect-free. This particular mechanism of\ncrystallization from amorphous phases is also observed during solid-phase\nepitaxial growth of $\\langle111\\rangle$ semiconductor crystals, where growth is\nrestrained to one dimension. We calculate the equivalent X-ray diffraction\npattern of the obtained nanotwin networks, providing grounds for experimental\nvalidation."
    },
    {
        "anchor": "Dispersive resonance bands within the space charge layer of metal-\n  semiconductor junction: Based on measurements of angle resolved photoemission, we report that in the\nPb/Ge(111)- \\sqrt{3}x\\sqrt{3} R30^\\circ structure, in addition to three bands\nresembling Ge heavy hole (HH), light hole (LH), and split off (SO) bulk band\nedges, a fourth dispersive band resembling the non split off (NSO) band is\nfound near the surface zone center. While three Ge bulk-like bands get\ndistorted due to strong coupling between Pb and Ge, the NSO-like band gets\nweaker and disappears for larger thickness of Pb, which, when combined with ab\ninitio calculations, indicates its localized nature within space charge layer.\nOur results are clearly important for designing electronics involved with\nmetal-semiconductor contacts.",
        "positive": "Electric-field switching of exciton spin splitting in coupled quantum\n  dots: We investigate theoretically the spin splitting of the exciton states in\nsemiconductor coupled quantum dots (CQDs) containing a single magnetic ion. We\nfind that the spin splitting can be switched on/off in the CQDs \\textit{via}\nthe \\textit{sp-d}exchange interaction using the electric field. An interesting\nbright-to-dark exciton transition can be found and significantly affects the\nphotoluminescence spectrum. This phenonmenon is induced by the transition of\nthe ground exciton state, arising from the hole mixing effect, between the\nbonding and antibonding states."
    },
    {
        "anchor": "Polycrystalline \u03b3-boron: As hard as polycrystalline cubic boron\n  nitride: The Vickers hardness of polycrystalline {\\gamma}-B was measured using a\ndiamond indentation method. The elastic properties of polycrystalline\n{\\gamma}-B (B=213.9 GPa, G=227.2 GPa, and E=503.3 GPa) were determined using\nultrasonic measurement at ambient condition. Under the loading force up to 20\nN, our test gave an average Vickers hardness in the asymptotic-hardness region\nof 30.3 GPa. The average fracture toughness was measured as 4.1MPa m1/2.\nAdditionally, We also measured the hardness and elastic properties of\npolycrystalline {\\beta}-B and PcBN for comparison. The hardness and elastic\nproperties for polycrystalline {\\gamma}-B was found to be very close to that of\nPcBN. Our results suggest that the polycrystalline {\\gamma}-B could be a\nsuperhard polycrystalline material for industrial applications.",
        "positive": "Trends on 3d Transition Metal Coordination on Monolayer MoS$_2$: Two-dimensional materials (2DM) have attracted much interest due to their\ndistinct optical, electronic, and catalytic properties. These properties can be\nby tuned a range of methods including substitutional doping or, as recently\ndemonstrated, by surface functionalization with single atoms, increasing even\nfurther 2DM portfolio. Here we theoretically and experimentally describe the\ncoordination reaction between MoS$_2$ monolayers with 3d transition metals\n(TMs), exploring the nature and the trend of MoS$_2$-TMs interaction. Density\nFunctional Theory calculations, X-Ray Photoelectron Spectroscopy (XPS), and\nPhotoluminescence (PL) point to the formation of MoS$_2$-TM coordination\ncomplexes, where the adsorption energy trend for 3d TM resembles the\ncrystal-field (CF) stabilization energy for weak-field complexes. Pearson's\ntheory for hard-soft acid-base and Ligand-field theory were applied to discuss\nthe periodic trends on 3d TM coordination on the MoS$_2$ surface. We found that\nsofter acids with higher ligand field stabilization energy, such as Ni$^{2+}$,\ntend to form bonds with more covalent character with MoS$_2$, which can be\nconsidered a soft base. On the other hand, harder acids, such as Cr$^{3+}$,\ntend to form bonds with more ionic character. Additionally, we studied the\ntrends in charge transfer and doping observed in the XPS and PL results, where\nmetals such as Ni led to an n-type of doping, while Cu functionalization\nresults in p-type doping. Therefore, the formation of coordination complexes on\nTMD's surface is demonstrated to be a promising and effective way to control\nand to understand the nature of the single-atom functionalization of TMD."
    },
    {
        "anchor": "Effective conductivity in association with model structure and spatial\n  inhomogeneity of polymer/carbon black composites: The relationship between effective conductivity and cell structure of\npolyethylene/carbon composites as well as between effective conductivity and\nspatial distribution of carbon black are discussed. Following Yoshida's model\nboth structures can, in a way, be said to be intermediate between the well\nknown Maxwell-Garnett (MG) and Bruggeman (BR) limiting structures. Using TEM\nphotographs on composites with various carbon blacks we have observed that the\nlarger is Garncarek's inhomogeneity measure H of two-dimensional (2D)\nrepresentative distribution of the carbon black, the smaller is the effective\nconductivity of the composite.",
        "positive": "Effect of Structural Transition on Magnetic Properties of Ca and Mn\n  co-substituted BiFeO3 Ceramics: Composition-driven structural transitions in Bi1-xCaxFe1-xMnxO3 ceramics\nprepared by the tartaric acid modified sol-gel technique have been studied to\nanalyze its effect on the magnetic properties of bismuth ferrite (BiFeO3). It\nwas observed that the co-substitution of Ca & Mn at Bi & Fe sites in BiFeO3\n(BFO) significantly suppress the impurity phases. The quantitative\ncrystallographic phase analysis has been carried out by double phase Rietveld\nanalysis of all the XRD patterns which indicates the existence of compositional\ndriven crystal structure transformation from rhombohederal (R3c space group,\nlower crystal symmetry) to the orthorhombic (Pbnm space group, higher crystal\nsymmetry) with the increase in substitution concentration due to excess\nchemical pressure (lattice strain). Magnetic measurements reveal that\nco-substituted BFO nanoparticles for x = 0.15 have enhanced remnant\nmagnetization about 14 times that of pure one due to the suppression of cycloid\nspin structure which could be explained in terms of field induced spin\nreorientation and weak ferromagnetism. However, at the morphological phase\nboundary (x = 0.15), the remnant and maximum magnetization at 8 T reaches a\nmaximum which indicates almost broken spin cycloid structure and further\nincrease in substitution results in the reduction of both magnetizations due to\nthe appearance of complete antiferromagnetic ordering in the orthorhombic\nstructure because of the significant contribution from the crystallographic\nphase of Pbnm space group (as obtained from double phase Rietveld analysis)."
    },
    {
        "anchor": "A New Model of Chemical Bonding in Ionic Melts: We developed a new physical model to predict macroscopic properties of\ninorganic molten systems using a realistic description of inter-atomic\ninteractions. Unlike the conventional approach, which tends to overestimate\nviscosity by several times, our systems consist of a set of ions with an\nadmixture of neutral atoms. The neutral atom subsystem is a consequence of the\ncovalent/ionic state reduction, occurring in the liquid phase. Comparison of\nthe calculated macroscopic properties (shear viscosity and self-diffusion\nconstants) with the experiment demonstrates good performance of our model. The\npresented approach is inspired by a significant degree of covalent interaction\nbetween the alkali and chlorine atoms, predicted by the coupled cluster theory.",
        "positive": "Enhanced ferroelectric properties of low-annealed SrBi2(Ta,Nb)2O9 thin\n  films for NvFeRAM applications: Micro-Raman spectroscopy and X-ray diffraction have been used to explore the\nlattice dynamics of Nb-substituted SrBi2(Ta1-xNbx)2O9 (SBTN) crystalline thin\nfilms annealed at low temperature, 700oC. It turned out that SrBi2(Ta1-xNbx)2O9\nfilms consist of fine-grained spherical structures for x=0.1-0.4, while the\nformation of rod-like grains occurs for x=0.5 due to the stress-induced\ntransformation of the thin film perovskite structure. Moreover, it was revealed\nthat during Nb cationic substitution Aurivillius phase formation was enhanced\nand become dominated in SBTN thin films and fluorite/pyrochlore phase formation\nwas highly suppressed. We assume that these changes are conditioned by the\nferrodistortion occurring in ferroic perovskites, namely by the tilting\ndistortion of (Ta,Nb)O6 octahedra for x=0.2-0.5. The octahedral tilting\ndistortion can change the coordination environment of the A-cite cation, as\nwell as it lowers the SBTN symmetry due to the differences in ionic radius and\nmass between Ta and Nb in the B-sites, that can lead to significant changes of\nthe SBTN crystal structure. The same nonmonotonic trends were observed for the\nferroelectric perovskite phase fraction and remanent polarization on Nb content\nin SBTN films. The substituting Nb atoms with a concentration of 10-20 % made\nit possible to increase the remanent polarization in 3 times and raise the\nperovskite phase fraction from 66% to 87%. Therefore, obtained results can be\nused for the production of lead-free thin films with a high remanent\npolarization under low annealing temperature, being promising for advanced\nnonvolatile random access ferroelectric memory (NvFeRAM) applications.\n  Keywords: ferroelectric, sol-gel method, perovskite structure,\ncrystallization annealing, defects, remanent polarization, SBTN films, Raman\nspectroscopy, Landau-Devonshire approach."
    },
    {
        "anchor": "A straightforward 2$\u03c9$ technique for the measurement of the Thomson\n  effect: We present a simplified, rapid, and accurate method for the measurement of\nthe thermoelectric Thomson coefficient by the dynamical heating of a suspended\nwire by an alternating current. By applying a temperature gradient across the\nwire, we find that the response at the second harmonic of the excitation\nfrequency is directly proportional to the Thomson coefficient. The absolute\nthermoelectric coefficient of a single material can therefore be extracted with\nhigh precision by a phase sensitive detector. We test our method on platinum\nand nickel wires and develop both analytical and numerical models to determine\nthe leading sources of error.",
        "positive": "Ferromagnetic resonance and interlayer exchange coupling in magnetic\n  multilayers with compositional gradients: Ferromagnetic resonance (FMR) in magnetic multilayers of type F1/f/F2, where\ntwo strongly ferromagnetic layers F1 and F2 are separated by a weakly magnetic\nspacer f with a compositional gradient along its thickness, is investigated.\nThe method allows to detect the weak signal from the spacer in additional to\nthe more pronounced and readily measured signal from the outer\nstrongly-magnetic layers, and thereby study the properties of the spacer as\nwell as the interlayer exchange interaction it mediates. Variable temperature\nFMR measurements, especially near the relevant Curie points, reveal a rich set\nof properties of the exchange interactions in the system. The obtained results\nare useful for designing and optimizing nanostructures with\nthermally-controlled magnetic properties."
    },
    {
        "anchor": "Magnetic Phase Imaging using Lorentz Near-field Electron Ptychography: Over the past few years, the combination of diffuser and near-field electron\nptychography has drawn more attention by its ability to recover large field of\nview with few diffraction patterns. In this paper, we purpose a novel design\nand implementation of amplitude diffuser. The amplitude diffuser introduces\nstructures to the illumination while reducing the inelastic scattering. And the\namplitude diffuser is implemented at the condenser lens aperture, allowing us\nto vary the illumination size under the same microscope setup. We demonstrate\nthe reconstruction results under both conventional Transmission Electron\nMicroscopy (TEM) mode as well as Lorentz mode.",
        "positive": "Structural instability of the ground state of the U2Mo compound: This work reports the structural instability at T=0 K of the U2Mo compound in\nthe structure C11b under the distortion related to the C66 elastic constant.\nThe electronic properties of U2Mo such density of states (DOS), bands and Fermi\nsurface (FS) are studied to understand the source of the instability. The C11b\nstructure can be interpreted as formed by parallel linear chains along the\nz-directions each one composed by successive U-Mo-U blocks. The hybridization\ndue to electronic interactions inside the U-Mo-U blocks is slightly modified\nunder the D6 distortion. The change in distance among chains modifies the U-U\ninteraction and produces the split of f-states. The distorted structure is\nstabilized by the energy lowering of the hybridized states, mainly between d-Mo\nand f-U states, together with the f-band split. Consequently, an induced\nPeierls distortion is produced in U2Mo due to the D6 distortion. In addition,\nthe results of this work remarks that the structure of the ground state of the\nU2Mo compound is other than the assumed C11b structure."
    },
    {
        "anchor": "Al$_{5+\u03b1}$Si$_{5+\u03b4}$N$_{12}$, a new Nitride compound: We report on the synthesis of new nitride-based compound by using annealing\nof AlN heteroepitaxial layers under a Si-atmosphere at temperatures between\n1350$^\\circ$C and 1550$^\\circ$C. The structure and stoichiometry of this\ncompound are investigated by high-resolution scanning transmission electron\nmicroscopy (HRSTEM), energy dispersive X-Ray (EDX) spectroscopy, and density\nfunctional theory (DFT) calculations. The identified structure is a derivative\nof the parent wurtzite AlN crystal where anion sublattice is fully occupied by\nN atoms and the cation sublattice is the stacking of 2 different planes along\n<0001>. The first one exhibits a $\\times$3 periodicity along <10-10> with 1/3\nof the sites being vacant. The rest of the sites in the cation sublattice are\noccupied by equal number of Si and Al atoms. Assuming a semiconducting alloy,\nwhich is expected to have a wide band gap, a range of stoichiometries is\nproposed, Al$_{5+\\alpha}$Si$_{5+\\delta}$N$_{12}$, with $\\alpha$ being between 0\nand 1/3 and $\\delta$ between 0 and 1/4.",
        "positive": "MatterGen: a generative model for inorganic materials design: The design of functional materials with desired properties is essential in\ndriving technological advances in areas like energy storage, catalysis, and\ncarbon capture. Generative models provide a new paradigm for materials design\nby directly generating entirely novel materials given desired property\nconstraints. Despite recent progress, current generative models have low\nsuccess rate in proposing stable crystals, or can only satisfy a very limited\nset of property constraints. Here, we present MatterGen, a model that generates\nstable, diverse inorganic materials across the periodic table and can further\nbe fine-tuned to steer the generation towards a broad range of property\nconstraints. To enable this, we introduce a new diffusion-based generative\nprocess that produces crystalline structures by gradually refining atom types,\ncoordinates, and the periodic lattice. We further introduce adapter modules to\nenable fine-tuning towards any given property constraints with a labeled\ndataset. Compared to prior generative models, structures produced by MatterGen\nare more than twice as likely to be novel and stable, and more than 15 times\ncloser to the local energy minimum. After fine-tuning, MatterGen successfully\ngenerates stable, novel materials with desired chemistry, symmetry, as well as\nmechanical, electronic and magnetic properties. Finally, we demonstrate\nmulti-property materials design capabilities by proposing structures that have\nboth high magnetic density and a chemical composition with low supply-chain\nrisk. We believe that the quality of generated materials and the breadth of\nMatterGen's capabilities represent a major advancement towards creating a\nuniversal generative model for materials design."
    },
    {
        "anchor": "Cs+ sputtered clusters from multi-walled carbon nanotubes and graphite: Experiments with multiwalled carbon nanotubes and graphite as targets in a\nsource of negative ions with cesium sputtering have shown that nanotubes with\nnanometer radii and micrometer length can be compared with micrometer size\ngraphite grains to understand the irradiation effects that include the\nformation, sputtering of carbon clusters and the resulting structural changes.\nThe simultaneous adsorption of cesium on the surface and bombardment by\nenergetic cesium ions is shown to play its role in the cluster formation and\nsputtering of carbon atoms and clusters and the cesium substituted carbon\nclusters as anions. Qualitative and quantitative sputtered species outputs are\nrelated to their respective structures. Structural changes are shown to occur\nin MWCNTs and seen in SEM micrographs. The individual identity of the heavily\nbombarded MWCNTs may have given way to the merged structures while effects on\nthe structure of heavily irradiated graphite grains size needs to be further\ninvestigated",
        "positive": "Separate-path electron and hole transport across pi-stacked\n  ferroelectrics for photovoltaic applications: Electron and hole separate-path transport is theoretically found in the\npi-stacked organic layers and columns. This effect might be a solution for the\ncharge recombination problem. The building molecules, named\n1,3,5-tricyano-2,4,6-tricarboxy-benzene, contain the mesogenic flat aromatic\npart and the terminal dipole groups which make the system ferroelectric. The\ndiffusion path of the electrons cuts through the aromatic rings, while holes\nhop between the dipole groups. The transmission function and the charge\nmobilities, especially for the holes, are very sensitive to the distance\nbetween the molecular rings, due to the overlap of the pi-type orbitals. We\nverified that the separation of the diffusion paths is not destroyed by the\napplication of the graphene leads. These features make the system suitable for\nthe efficient solar cells, with the carrier mobilities higher than these in the\norganometal halide perovskites."
    },
    {
        "anchor": "Strain hardening-softening oscillations induced by nanoindentation in\n  bulk solids: Nanoindentation is a widely used method for sensitive exploration of the\nmechanical properties of micromechanical systems. We derived an empirical\nanalysis technique to extract stress-strain field gradient and divergence\nrepresentations from nanoindentation measurements. With this approach local\ngradients and heterogeneities can be discovered to obtain more detail about the\nsample's microstructure, thus enhancing the analytic capacity of the\nnanoindentation technique. We analysed nanoindentation tests of bulk solid\nsubstrates, namely bearing and tooling steel, and fused silica. Oscillations of\nthe stress-strain field gradient and divergence induced in the subsurface layer\nby the nanoindentation experiment were revealed. The oscillations were\nespecially prominent in single measurements at low indentation depths (< 100\nnm), whereas they were concealed in the averaged datasets. The amplitude of\nstress-strain field divergence oscillations decayed as a sublinear power-law\nwhen the indenter approached deeper atomic layers, with an exponent -0.9 for\nthe steel and -0.8 for the fused silica. The oscillations were interpreted as\nalternating strain hardening-softening cycles induced in the subsurface layers\nunder the indenter load. A selective assessment of elastic and plastic\nstress-strain field components indicated an elastic-plastic deformation process\nwhere the normal strain is transformed into the shear strain leading to a\nplastic deformation.",
        "positive": "Thermal contraction in silicon nanowires at low temperatures: The thermal expansion effect of silicon nanowires (SiNW) in [100], [110] and\n[111] directions with different sizes is theoretically investigated. At low\ntemperatures, all SiNW studied exhibit thermal contraction effect due to the\nlowest energy of the bending vibration mode which has negative effect on the\ncoefficient of thermal expansion (CTE). The CTE in [110] direction is\ndistinctly larger than the other two growth directions because of the\nanisotropy of the bending mode in SiNW. Our study reveals that CTE decreases\nwith an increase of the structure ratio $\\gamma=length/diameter$, and is\nnegative in whole temperature range with $\\gamma=1.3$."
    },
    {
        "anchor": "High-Temperature Annealing of TiO2 Nanotube Membranes for Efficient\n  Dye-Sensitized Solar Cells: We fabricate photo-anodes by transferring anodic TiO2 nanotube membranes in\ntube-top-down configuration on FTO glass, and use them for constructing\nfrontside illuminated dye-sensitized solar cells. Prior to solar cell\nconstruction, the tube-based photo-anodes are crystallized at different\ntemperatures (400-800{\\deg}C), and the effects of tube electron transport\nproperties on the photovoltaic performance of the solar cells are investigated.\nWe show that improved solar cell efficiencies (up to ca. 8.0%) can be reached\nby high-temperature treatment of the tube membranes. Consistently with electron\ntransport time measurements, remarkably enhanced electron mobility is enabled\nwhen tube membranes are crystallized at 600{\\deg}C.",
        "positive": "Elastocaloric response of PbTiO3 predicted from a first-principles\n  effective Hamiltonian: A first-principles based effective Hamiltonian is used within a molecular\ndynamics simulation to study the elastocaloric effect in PbTiO3. It is found\nthat the transition temperature is a linear function of uniaxial tensile\nstress. Negative temperature change is calculated, when the uniaxial tensile\nstress is switched off, as a function of initial temperature\nDelta-T(T_initial). It is predicted that the formation of domain structures\nunder uniaxial tensile stress degrades the effectiveness of the elastocaloric\neffect."
    },
    {
        "anchor": "Tunable magnetic states in h-BN sheets: Magnetism in 2D atomic sheets has attracted considerable interest as its\nexistence could allow the development of electronic and spintronic devices. The\nexistence of magnetism is not sufficient for devices, however, as states must\nbe addressable and modifiable through the application of an external drive. We\nshow that defects in hexagonal boron nitride present a strong interplay between\nthe the N-N distance in the edge and the magnetic moments of the defects. By\nstress-induced geometry modifications, we change the ground state magnetic\nmoment of the defects. This control is made possible by the triangular shape of\nthe defects as well as the strong spin localisation in the magnetic state.",
        "positive": "Optimizing thermoelectric performances of low-temperature SnSe compounds\n  by electronic structure design: Recently SnSe compound was reported to have a peak thermoelectric figure-5\nof-merit (ZT) of 2.62 at 923 K, but the ZT values at temperatures below 750 K\nare relatively low. In this work, the electronic structures of SnSe are\ncalculated using the density functional theory, and the electro- and\nthermo-transport properties upon varying chemical potential (or carrier\ndensity) are evaluated by the semi-classic Boltzmann transport theory, showing\nthat the calculated ZT values along the a10 and c-axes below 675 K are in\nagreement with reported values, but that along the b-axis can be as high as\n2.57 by optimizing the carrier concentration to ~3.6*1019 cm-3. It is revealed\nthat a mixed ionic-covalent bonding and heavy-light band overlapping near the\nvalence band are the reasons for the higher thermoelectric performance"
    },
    {
        "anchor": "Realization of the Single-pair-Weyl Phonons with the Maximum Charge\n  Number in Acoustic Crystals: To observe the Weyl phonon (WP) with the maximum charge and to design a\nrealistic material structure containing only single-pair-WPs have long been\nconsidered two challenges in the field of topology physics. Here we have\nsuccessfully designed an acoustic crystal to realize the single-pair-WPs with\nthe maximum charge for the first time. Our theoretical simulations on acoustic\nband dispersions demonstrate that protected by the time-reversal symmetry\n($\\cal T$) and the point group symmetries, a WP with the charge -4\n($\\mathcal{C}=-4$) and another WP with $\\mathcal{C}=+4$ are located at the\nhigh-symmetry point $\\Gamma$ and R, respectively, with the absence of any other\nkinds of WPs. Moreover, the singe-pair-WPs obtained here are designed by the\nsimplest two-band mode, and the related quadruple-helicoid Fermi acrs can be\nobserved clearly in experiments, since they aren't covered by any bulk bands\nand hybridized by other kinds of WPs. Our theoretical results provide a\nreliable acoustic crystal to study the topological properties of the\nsingle-pair-WPs with the maximum charge for experimentalists in this field.",
        "positive": "Controlling the dopant profile for SRH suppression at low current\n  densities in $\u03bb\\approx$ 1330nm GaInAsP light-emitting diodes: The quantum efficiency of double hetero-junction light-emitting diodes (LEDs)\ncan be significantly enhanced at low current density by tailoring the spatial\nprofile of dopants to suppress Shockley-Read-Hall (SRH) recombination. To\ndemonstrate this effect we model, design, grow, fabricate, and test a GaInAsP\nLED ($\\lambda \\approx$ 1330nm) with an unconventional dopant profile. Compared\nagainst that of our control design, which is a conventional $n^+$-$n$-$p^+$\ndouble hetero-junction LED, the dopant profile near the $n$-$p^+$\nhetero-structure of the new design displaces the built-in electric field in\nsuch a way as to suppress the J02 space charge recombination current. The\ndesign principle generalizes to other material systems and could be applicable\nto efforts to observe and exploit electro-luminescent refrigeration at\npractical power densities."
    },
    {
        "anchor": "Drastic Changes in Dielectric Function of Silver Under dc Voltage: Significant changes of the relative permittivity of a silver film have been\ndetected using the surface plasmon resonance (SPR) method when a constant\nelectric field is applied to a MDM (metal-dielectric-metal) nanostructure. The\nstructure looks like a capacitor with a 177-nm dielectric corundum film placed\nbetween two silver films 49nm and 37nm thick. The effect manifests itself as a\nnoticeable change of the reflectivity of the structure when the voltage of up\nto 30V is applied to the electrodes. We have a good agreement between the\ntheory and experiment only if we suppose that the optical parameters of anode\nand cathode silver films change differently and the Al_2O_3 film absorbs the\nincident light. The refraction coefficient of the cathode silver layer is shown\nto become zero when the applied voltage is above 16V.",
        "positive": "Doping graphene with metal contacts: Making devices with graphene necessarily involves making contacts with\nmetals. We use density functional theory to study how graphene is doped by\nadsorption on metal substrates and find that weak bonding on Al, Ag, Cu, Au and\nPt, while preserving its unique electronic structure, can still shift the Fermi\nlevel with respect to the conical point by $\\sim 0.5$ eV. At equilibrium\nseparations, the crossover from $p$-type to $n$-type doping occurs for a metal\nwork function of $\\sim 5.4$ eV, a value much larger than the graphene work\nfunction of 4.5 eV. The numerical results for the Fermi level shift in graphene\nare described very well by a simple analytical model which characterizes the\nmetal solely in terms of its work function, greatly extending their\napplicability."
    },
    {
        "anchor": "Resonant properties of dipole skyrmions in amorphous Fe/Gd multilayers: The dynamic response of dipole skyrmions in Fe/Gd multilayer films is\ninvestigated by ferromagnetic resonance measurements and compared to\nmicromagnetic simulations. We detail thickness and temperature dependent\nstudies of the observed modes as well as the effects of magnetic field history\non the resonant spectra. Correlation between the modes and the magnetic phase\nmaps constructed from real-space imaging and scattering patterns allows us to\nconclude the resonant modes arise from local topological features such as\ndipole skyrmions but does not depend on the collective response of a closed\npacked lattice of these chiral textures. Using, micromagnetic modeling, we are\nable to quantitatively reproduce our experimental observations which suggests\nthe existence of localized spin-wave modes that are dependent on the helicity\nof the dipole skyrmion. We identify four localized spin wave excitations for\nthe skyrmions that are excited under either in-plane or out-of-plane r.f.\nfields. Lastly we show that dipole skyrmions and non-chiral bubble domains\nexhibit qualitatively different localized spin wave modes.",
        "positive": "Negative Thermal Expansion in cubic ZrW2O8: Role of Phonons in Entire\n  Brillouin Zone From ab-inito Calculations: We report ab-inito density functional theory calculation of phonons in cubic\nphase of ZrW2O8 in the entire Brillouin zone and identify specific anharmonic\nphonons that are responsible for large negative thermal expansion (NTE) in\nterms of translation, rotation and distortion of WO4 and ZrO6. We have used\ndensity functional calculations to interpret the experimental phonon spectra as\na function of pressure and temperature as reported in literature. We discover\nthat the phonons showing anharmonicty with temperature are different from those\nshowing anharmonicity with pressure although both are of similar frequencies.\nOnly the latter phonons are associated with NTE. Therefore the cubic and/or\nquadratic anharmonicity of phonons is not relevant to NTE but just the volume\ndependence of frequencies. The calculations are able to reproduce the observed\nanomalous trends, namely, the softening of the low frequency peak at about 5\nmeV in the phonon spectra with pressure and its hardening with temperature,\nwhile both the changes involve a compression of the lattice."
    },
    {
        "anchor": "Extrinsic Proton NMR Studies of Mg(OH)$_2$ and Ca(OH)$_2$: We studied narrow $^1$H NMR spectra of Mg(OH)$_2$ and Ca(OH)$_2$ powders at\n100$-$355 K and 42$-$59 MHz using pulsed NMR techniques. The Fourier\ntransformed NMR spectra of the proton free-induction signals show the\nsuperposition of broad and narrow components, which can be assigned to immobile\nprotons and extrinsic mobile protons, respectively. We found that a narrow\nspectrum develops on heating above about $T_c$ = 260 K and widens above a\nLarmor frequency of about $f_c$ = 50 MHz for Mg(OH)$_2$. The\ntemperature-induced NMR spectrum and the characteristic frequency $f_c$ of 50\nMHz are the noteworthy features of the nuclear spin fluctuation spectra of the\nextrinsic protons.",
        "positive": "Multiscale modelling of structure formation of C$_{60}$ on insulating\n  CaF$_2$ substrates: Morphologies of adsorbed molecular films are of interest in a wide range of\napplications. To study the epitaxial growth of these systems in computer\nsimulations requires access to long time and length scales and one typically\nresorts to kinetic Monte Carlo (KMC) simulations. However, KMC simulations\nrequire as input transition rates and their dependence on external parameters\n(such as temperature). Experimental data allows only limited and indirect\naccess to these rates, and models are often oversimplified. Here we follow a\nbottom-up approach and aim to systematically construct all relevant rates for\nan example system that has shown interesting properties in experiments,\nbuckminsterfullerene on a calcium fluoride substrate. We develop classical\nforce fields (both atomistic and coarse-grained) and perform molecular dynamics\nsimulations of the elementary transitions in order to derive explicit\nexpressions for the transition rates with a minimal number of free parameters."
    },
    {
        "anchor": "Phase Coexistence Near a Morphotropic Phase Boundary in Sm-doped BiFeO3\n  Films: We have investigated heteroepitaxial films of Sm-doped BiFeO3 with a\nSm-concentration near a morphotropic phase boundary. Our high-resolution\nsynchrotron X-ray diffraction, carried out in a temperature range of 25C to\n700C, reveals substantial phase coexistence as one changes temperature to\ncrossover from a low-temperature PbZrO3-like phase to a high-temperature\northorhombic phase. We also examine changes due to strain for films greater or\nless than the critical thickness for misfit dislocation formation.\nParticularly, we note that thicker films exhibit a substantial volume collapse\nassociated with the structural transition that is suppressed in strained thin\nfilms.",
        "positive": "Spin-polarized imaging of the antiferromagnetic structure and\n  field-tunable bound states in kagome magnet FeSn: Kagome metals are as an exciting playground for the explorations of novel\nphenomena at the intersection of topology, electron correlations and magnetism.\nThe family of FeSn-based kagome magnets in particular attracted a lot of\nattention for simplicity of the layered crystal structure and tunable\ntopological electronic band structure. Despite a significant progress in\nunderstanding their bulk properties, surface electronic and magnetic structures\nare yet to be fully explored in many of these systems. In this work, we focus\non a prototypical kagome metal FeSn. Using a combination of spin-averaged and\nspin-polarized scanning tunneling microscopy, we provide the first atomic-scale\nvisualization of the layered antiferromagnetic structure at the surface of\nFeSn. In contrast to the field-tunable electronic structure of cousin material\nFe3Sn2 that is a ferromagnet, we find that electronic density-of-states of FeSn\nis robust to the application of external magnetic field. Interestingly, despite\nthe field-insensitive electronic band structure, FeSn exhibits bounds states\ntied to specific impurities with large effective moments that strongly couple\nto the magnetic field. Our experiments provide microscopic insights necessary\nfor theoretical modeling of FeSn and serve as a spring board for spin-polarized\nmeasurements of topological magnets in general."
    },
    {
        "anchor": "In situ and non situ surface x-ray scattering studies of in plane Cs+\n  ordering in Helmholtz planes of Pt(111) surface: In-plane ordering of Cs+ layers in Helmhotlz planes was studied on Pt(111)\nsurface in 0.1 M CsF electrolyte solutions with synchtrotron surface x-ray\nscattering techniques. The ordering was measured in a new transmission cell,\ndesigned for in situ and non situ measurements and high-temperature sample\nannealing all in the cell without sample transfer steps. At -850 mV vs.\nAg/AgCl, (2x2) in-plane scattering peaks were weak under in situ condition and\ngrew rapidly under non situ condition as the surface emersed from the\nelectrolyte. The models for the (2x2) structures are presented and differences\nbetween in situ and non situ conditions are discussed.",
        "positive": "Study of the solute clusters/enrichment at early stage of ageing in\n  Mg-Zn-Gd alloys by atom probe tomography: The chemical enrichment/ordering of solute atoms in Mg matrix are crucial to\nunderstand the formation mechanism of long-period stacking ordered (LPSO)\nstructures. In this study, three-dimensional distribution of solute elements in\nan Mg-Zn-Gd alloy during ageing process is quantitatively characterized by\nthree-dimensional atom probe (3DAP) tomography. Based on the radius\ndistribution function, it is found that Zn-Gd solute pairs in Mg matrix appear\nmainly in two peaks at early stage of ageing and the separation distance\nbetween Zn and Gd atoms is well rationalized by the first-principles\ncalculation. Moreover, the fraction of Zn-Gd solute pairs increases first and\ndecreases subsequently due to the precipitation of LPSO structures. Moreover,\nthe composition of structural unit in LPSO structure and the solute enrichment\naround it are quantified. It is found that Zn and Gd elements are synchronized\nin the LPSO structure, and solute segregation of pure Zn or Gd is not observed\nat the transformation front of the LPSO structure in this alloy. In addition,\nthe crystallography of transformation front is further determined by 3DAP data."
    },
    {
        "anchor": "Low magnetic field reversal of electric polarization in a Y-type\n  hexaferrite: Magnetoelectric multiferroics in which ferroelectricity and magnetism coexist\nhave attracted extensive attention because they provide great opportunities for\nthe mutual control of electric polarization by magnetic fields and\nmagnetization by electric fields. From a practical point view, the main\nchallenge in this field is to find proper multiferroic materials with a high\noperating temperature and great magnetoelectric sensitivity. Here we report on\nthe magnetically tunable ferroelectricity and the giant magnetoelectric\nsensitivity up to 250 K in a Y-type hexaferrite, BaSrCoZnFe11AlO22. Not only\nthe magnitude but also the sign of electric polarization can be effectively\ncontrolled by applying low magnetic fields (a few hundreds of Oe) that modifies\nthe spiral magnetic structures. The magnetically induced ferroelectricity is\nstabilized even in zero magnetic field. Decayless reproducible flipping of\nelectric polarization by oscillating low magnetic fields is shown. The maximum\nlinear magnetoelectric coefficient reaches a high value of ~ 3.0\\times10^3 ps/m\nat 200 K.",
        "positive": "Mn-site doping and its effect on inverted hysteresis and thermomagnetic\n  irreversibility behavior of antiferromagnetic Mn$_5$Si$_3$ alloy: The structural and magnetic behavior of Mn-site doped intermetallic manganese\nsilicide alloys of nominal compositions Mn$_{5-x}$A$_x$Si$_3$ ($x$ = 0.05, 0.1,\n0.2 and A = Ni, Cr) have been investigated with a focus to the inverted\nhysteresis behavior and thermomagnetic irreversibility. Room temperature x-ray\npowder diffraction data confirm that all the doped alloys crystallize in\nhexagonal $D8_8$ type structure with space group $P6_3/mcm$. The doped alloys\nare found to show paramagnetic (PM) - collinear antiferromagnetic (AFM2) -\nnoncollinear antiferromagnetic (AFM1) transitions during cooling from room\ntemperature. A significant decrease in the critical values of both AFM1-AFM2\ntransition temperatures and fields have been observed with the increasing Ni/Cr\nconcentration. Inverted hysteresis loop, field-induced arrest, and\nthermomagnetic arrest, the key features of the undoped Mn$_5$Si$_3$ alloy, are\nfound to be significantly affected by the Mn-site doping and eventually\nvanishes with 4\\% doping."
    },
    {
        "anchor": "Temperature Dependence of Magnetic Excitations: Terahertz Magnons above\n  the Curie Temperature: When an ordered spin system of a given dimensionality undergoes a second\norder phase transition the dependence of the order parameter i.e. magnetization\non temperature can be well-described by thermal excitations of elementary\ncollective spin excitations (magnons). However, the behavior of magnons\nthemselves, as a function of temperature and across the transition temperature\nTC, is an unknown issue. Utilizing spin-polarized high resolution electron\nenergy loss spectroscopy we monitor the high-energy (terahertz) magnons,\nexcited in an ultrathin ferromagnet, as a function of temperature. We show that\nthe magnons' energy and lifetime decrease with temperature. The\ntemperature-induced renormalization of the magnons' energy and lifetime depends\non the wave vector. We provide quantitative results on the temperature-induced\ndamping and discuss the possible mechanism e.g., multi-magnon scattering. A\ncareful investigation of physical quantities determining the magnons'\npropagation indicates that terahertz magnons sustain their propagating\ncharacter even at temperatures far above TC.",
        "positive": "Local geometry around B atoms in B/Si(111) from polarized x-ray\n  absorption spectroscopy: The arrangement of B~atoms in a doped\nSi(111)-$(\\sqrt{3}\\times\\sqrt{3})R30^{\\circ}$:B system was studied using\nnear-edge x-ray absorption fine structure (NEXAFS). Boron atoms were deposited\nvia segregation from the bulk by flashing the sample repeatedly. The positions\nof B~atoms are determined by comparing measured polarized (angle-dependent)\nNEXAFS spectra with spectra calculated for various structural models based on\nab-initio total energy calculations. It is found that most of boron atoms are\nlocated in sub-surface L$_{1}^{c}$ positions, beneath a Si atom. However,\ndepending on the preparation method a significant portion of B~atoms may be\nlocated elsewhere. A possible location of these non-L$_{1}^{c}$-atoms is at the\nsurface, next to those Si atoms which form the\n$(\\sqrt{3}\\times\\sqrt{3})R30^{\\circ}$ reconstruction."
    },
    {
        "anchor": "Temperature dependence of spin resonance in cobalt substituted NiZnCu\n  ferrites: Cobalt substitutions were investigated in Ni0.4Zn0.4Cu0.2Fe2O4 ferrites,\ninitial complex permeability was then measured from 1 MHz to 1 GHz. It appears\nthat cobalt substitution led to a decrease in the permeability and an increase\nin the \\mus\\timesfr factor. As well, it gave to the permeability spectrum a\nsharp resonance character. We also observed a spin reorientation occurring at a\ntemperature depending on the cobalt content. Study of the complex permeability\nversus temperature highlighted that the most resonant character was obtained at\nthis temperature. This shows that cobalt contribution to second order\nmagnetocrystalline anisotropy plays a leading role at this temperature.",
        "positive": "2D van der Waals Nanoplatelets with Robust Ferromagnetism: We have synthesized unique colloidal nanoplatelets of the ferromagnetic\ntwo-dimensional (2D) van der Waals material CrI3 and have characterized these\nnanoplatelets structurally, magnetically, and by magnetic circular dichroism\nspectroscopy. The isolated CrI3 nanoplatelets have lateral dimensions of ~25 nm\nand ensemble thicknesses of only ~4 nm, corresponding to just a few CrI3\nmonolayers. Magnetic and magneto-optical measurements demonstrate robust 2D\nferromagnetic ordering in these nanoplatelets with Curie temperatures similar\nto those observed in bulk CrI3, despite the strong spatial confinement. These\ndata also show magnetization steps akin to those observed in micron-sized\nfew-layer 2D sheets and associated with concerted spin-reversal of individual\nCrI3 layers within few-layer van der Waals stacks. Similar data have also been\nobtained for CrBr3 and anion-alloyed Cr(I1-xBrx)3 nanoplatelets. These results\nrepresent the first example of laterally confined 2D van der Waals ferromagnets\nof any composition. The demonstration of robust ferromagnetism at nanometer\nlateral dimensions opens new doors for miniaturization in spintronics devices\nbased on van der Waals ferromagnets."
    },
    {
        "anchor": "Increasing the Collection Efficiency in Selenium Thin-Film Solar Cells\n  Using a Closed-Space Annealing Strategy: Elemental selenium is a promising wide-bandgap ($E_\\mathrm{G}\\approx$ 1.95\neV) photovoltaic material for the next generation of thin-film solar cells. To\nrealize high-efficiency selenium solar cells, it is crucial to optimize the\ncrystallization process of the selenium thin-film photoabsorber. However, the\nhigh vapor pressure of selenium restricts the processing conditions to a\ncompromise between the growth of large crystal grains and the formation of\npinholes. In this study, we introduce a closed-space annealing (CSA) strategy\ndesigned to suppress the sublimation of selenium, enabling thermal annealing\nprocesses at higher temperatures and for longer periods of time. As a result,\nwe consistently improve carrier collection and the overall photovoltaic device\nperformance in our selenium solar cells. By characterizing the carrier dynamics\nin our devices, we conclude that the observed improvements result from a\nreduction in charge transfer resistance rather than an increase in carrier\ndiffusion length. The CSA strategy is a promising method for controlling\nsurface morphology and roughness without reducing crystal grain sizes, which\npaves the way for further advancements in the efficiency and reproducibility of\nselenium thin-film solar cells.",
        "positive": "Pseudogap behavior of phase-separated Sm$_{1-x}$Ca$_x$MnO$_3$ : A\n  comparative photoemission study with double exchange: Using valence band photoemission we have demonstrated the presence of a\npseudogap in the near Fermi level electronic spectrum of some of the mixed\nphase compositions of Sm$_{1-x}$Ca$_x$MnO$_3$ system. The pseudogap was found\nto grow in size over a large region of the phase diagram of this system,\nfinally leading to a metal-insulator transition. We have made a study comparing\nthe near Fermi level behaviors of this system to those of a canonical double\nexchange system, namely, La$_{1-x}$Sr$_x$MnO$_3$. This study intends to\nhighlight one of the important differences between the phase separated and\ndouble exchange colossal magnetoresistance systems in the nature of their\nenergy gaps across the metal-insulator transitions. These differences could be\nascribed to the distortions in the MnO$_6$ octahedra of their structures that\nregulate the localization of charge carriers. We have discussed our results\nfrom the point of view of models based on the idea of phase separation."
    },
    {
        "anchor": "Magneto-elastic coupling and magnetocaloric effect in hexagonal\n  Mn-Fe-P-Si compounds: Structural, magnetic and magnetocaloric properties of Fe2P-based Mn-Fe-P-Si\ncompounds were investigated. The study reveals a large magneto-elastic coupling\nthat starts to develop in the paramagnetic state and grows when the\nferromagnetic transition temperature is approached. Based on the behavior of\nthe magneto-elastic coupling, we show the thermal evolution of the magnetic\nmoments. On cooling, magnetic moments on the tetrahedral site form and\ngradually increase in the paramagnetic state. At the magnetic ordering\ntemperature the moments attain a much larger value in a discontinuous step. We\nalso find that the hysteresis and magnetic entropy change are correlated with\ndiscontinuous changes in the lattice parameters at the transition temperature.\nSmall hysteresis can be obtained while maintaining giant magnetocaloric effect.",
        "positive": "MnAs overlayer on GaN(0001)-(1x1) - its growth, morphology and\n  electronic structure: Spontaneous formation of grains has been observed for the MnAs layer grown by\nmeans of MBE on the GaN(0001)-(1x1) surface. Electronic structure of the system\nwas investigated in situ by resonant photoemission spectroscopy. Density of the\nvalence band states of MnAs and its changes due to increase of the layer\nthickness were revealed."
    },
    {
        "anchor": "Band gap opening by two-dimensional manifestation of Peierls instability\n  in graphene: Using first-principles calculations of graphene having high-symmetry\ndistortion or defects, we investigate band gap opening by chiral symmetry\nbreaking, or intervalley mixing, in graphene and show an intuitive picture of\nunderstanding the gap opening in terms of local bonding and antibonding\nhybridizations. We identify that the gap opening by chiral symmetry breaking in\nhoneycomb lattices is an ideal two-dimensional (2D) extension of the Peierls\nmetal-insulator transition in 1D linear lattices. We show that the spontaneous\nKekule distortion, a 2D version of the Peierls distortion, takes place in\nbiaxially strained graphene, leading to structural failure. We also show that\nthe gap opening in graphene antidots and armchair nanoribbons, which has been\nattributed usually to quantum confinement effects, can be understood with the\nchiral symmetry breaking.",
        "positive": "Monolayer Characteristics of Pyrene Mixed with Stearic Acid at the\n  Air-Water Interface: In the present communication we report the monolayer characteristics of\npyrene mixed with stearic acid (SA) at the air-water interface. The monolayer\nproperties are investigated by recording and analyzing the surface\npressure-area per molecule isotherm (pi-A) of the pyrene-SA mixed films. It is\nobserved that the pyrene and SA are miscible in the mixed monolayer. This\nmiscibility/nonideality leads to phase separation between the constituent\ncomponents (pyrene and SA). BAM image of the mixed monolayer confirms the\nmiscibility or nonideal mixing at the mixed monolayer."
    },
    {
        "anchor": "Nanoscale Quantification of Octahedral Tilts in Perovskite Films: NiO6-octahedral tilts in ultrathin LaNiO3 films were studied using position\naveraged convergent beam electron diffraction (PACBED) in scanning transmission\nelectron microscopy. Both the type and magnitude of the octahedral tilts were\ndetermined by comparing PACBED experiments to frozen phonon multislice\nsimulations. It is shown that the out-of-plane octahedral tilt of an epitaxial\nfilm under biaxial tensile stress (0.78 % in-plane tensile strain) increases by\n~ 20%, while the in-plane rotation decreases by ~ 80%, compared to the\nunstrained bulk material.",
        "positive": "Nature of the electronic states involved in the chemical bonding and\n  superconductivity at high pressure in SnO: We have investigated the electronic structure and the Fermi surface of SnO\nusing density functional theory (DFT) calculations within recently proposed\nexchange-correlation potential (PBE+mBJ) at ambient conditions and high\npressures up to 19.3 GPa where superconductivity was observed. It was found\nthat the Sn valence states 5s, 5p, and 5d are strongly hybridized with the O\n2p-states, and that our DFT-calculations are in good agreement with O K-edge\nX-ray spectroscopy measurements for both occupied and empty states. It was\ndemonstrated that the metallic states appearing under pressure in the\nsemiconducting gap stem due to the transformation of the weakly hybridized O\n2p-Sn 5sp subband corresponding to the lowest valence state of Sn in SnO. We\ndiscuss the nature of the electronic states involved in chemical bonding and\nformation of the hole and electron pockets with nesting as a possible way to\nsuperconductivity."
    },
    {
        "anchor": "Self-ordered Mo-oxide Nanotube Arrays as Precursor for Aligned MoOx/MoS2\n  Core-Shell Nanotubular Structures with a High Density of Reactive Sites: In the present work we demonstrate the self-organized formation of anodic\nMo-oxide nanotube arrays grown on a Mo sheet under suitable electrochemical\nconditions in glycerol/NH4F electrolytes. The resulting amorphous tubes can be\ncrystallized by annealing to MoO2 or MoO3. The tube walls then can be further\nsulfurized fully or partially to Mo-sulfide to form well-ordered arrays of\nvertically aligned MoOx/MoS2 nanotubes. Under optimized conditions, defined\nMoS2 sheets form on the oxide walls in a layer by layer low angle zig-zag\narrangement that provide a high density of reactive stacking faults. These\ncore-shell nanotube arrays, consisting of tubes with a conductive suboxide core\nand a functional high defect density MoS2 coating, are highly promising for\napplications such as electrocatalysis (hydrogen evolution) or ion insertion\ndevices.",
        "positive": "Extension of the simulation code ACAT to treat real atomic positions: We have investigated plasma-surface interactions with molecular dynamics (MD)\nsimulations. It, however, is high cost computation and is limited to\nsimulations for materials of nanometer order. In order to overcome the\nlimitation, a complementary model based on binary collision approximation (BCA)\ncan be established. We employed a BCA-based simulation code ACAT and extended\nto handle any structure involving crystalline and amorphous. The extended code,\nnamed \"ACaT\", stores all positions of projectile and target atoms and\nvelocities of recoil atoms, so it can be combined with the MD code. It also\nholds the potential to reproduce channeling phenomena. Thus it is expected to\nbe useful for evaluation of channeling effects."
    },
    {
        "anchor": "Localized versus itinerant magnetic moments in Na0.72CoO2: Based on experimental 59Co-NMR data in the temperature range between 0.1 and\n300 K, we address the problem of the character of the Co 3d-electron based\nmagnetism in Na0.7CoO2. Temperature dependent 59Co-NMR spectra reveal different\nCo environments below 300 K and their differentiation increases with decreasing\ntemperature. We show that the 23Na- and 59Co-NMR data may consistently be\ninterpreted by assuming that below room temperature the Co 3d-electrons are\nitinerant. Their magnetic interaction appears to favor an antiferromagnetic\ncoupling, and we identify a substantial orbital contribution corb to the\nd-electron susceptibility. At low temperatures corb seems to acquire some\ntemperature dependence, suggesting an increasing influence of spin-orbit\ncoupling. The temperature dependence of the spin-lattice relaxation rate\nT1-1(T) confirms significant variations in the dynamics of this electronic\nsubsystem between 200 and 300K, as previously suggested. Below 200 K, Na0.7CoO2\nmay be viewed as a weak antiferromagnet with TN below 1 K but this scenario\nstill leaves a number of open questions.",
        "positive": "Elucidating the Structure of the Magnesium Aluminum Chloride Complex\n  electrolyte for Magnesium-ion batteries: We present a rigorous analysis of the Magnesium Aluminum Chloro Complex\n(MACC) in tetrahydrofuran (THF), one of the few electrolytes that can\nreversibly plate and strip Mg. We use \\emph{ab initio} calculations and\nclassical molecular dynamics simulations to interrogate the MACC electrolyte\ncomposition with the goal of addressing two urgent questions that have puzzled\nbattery researchers: \\emph{i}) the functional species of the electrolyte, and\n\\emph{ii}) the complex equilibria regulating the MACC speciation after\nprolonged electrochemical cycling, a process termed as conditioning, and after\nprolonged inactivity, a process called aging. A general computational strategy\nto untangle the complex structure of electrolytes, ionic liquids and other\nliquid media is presented. The analysis of formation energies and\ngrand-potential phase diagrams of Mg-Al-Cl-THF suggests that the MACC\nelectrolyte bears a simple chemical structure with few simple constituents,\nnamely the electro-active species MgCl$^+$ and AlCl$_4^-$ in equilibrium with\nMgCl$_2$ and AlCl$_3$. Knowledge of the stable species of the MACC electrolyte\nallows us to determine the most important equilibria occurring during\nelectrochemical cycling. We observe that Al deposition is always preferred to\nMg deposition, explaining why freshly synthesized MACC cannot operate and needs\nto undergo preparatory conditioning. Similarly, we suggest that aluminum\ndisplacement and depletion from the solution upon electrolyte resting (along\nwith continuous MgCl$_2$ regeneration) represents one of the causes of\nelectrolyte aging. Finally, we compute the NMR shifts from shielding tensors of\nselected molecules and ions providing fingerprints to guide future experimental\ninvestigations."
    },
    {
        "anchor": "Origin of Diffuse Scattering in Relaxor Ferroelectrics: High-pressure and variable temperature single crystal synchrotron X-ray\nmeasurements combined with first-principles based molecular dynamics\nsimulations study diffuse scattering in the relaxor ferroelectric system PSN\n(PbSc$_{1/2}$Nb$_{1/2}$O$_3$). Constant temperature experiments show pressure\ninduced transition to the relaxor phase at different temperatures characterized\nby butterfly and rod shaped diffuse scattering around the $\\{$h00$\\}$ and\n$\\{$hh0$\\}$ Bragg spots, respectively. The simulations reproduce the observed\ndiffuse scattering features as well as their pressure-temperature behavior, and\nshow that they arise from polarization correlations between chemically-ordered\nregions, which in previous simulations were shown to behave as polar\nnanoregions. Simulations also exhibit radial diffuse scattering (elongated\ntowards and away from {\\bf Q}=(000)), that persists even in the paraelectric\nphase, consistent with previous neutron experiments on\n(PbMg$_{1/3}$Nb$_{2/3}$O$_3$) (PMN)",
        "positive": "Ferromagnetism in nanoscale BiFeO3: A remarkably high saturation magnetization of ~0.4mu_B/Fe along with room\ntemperature ferromagnetic hysteresis loop has been observed in nanoscale (4-40\nnm) multiferroic BiFeO_3 which in bulk form exhibits weak magnetization\n(~0.02mu_B/Fe) and an antiferromagnetic order. The magnetic hysteresis loops,\nhowever, exhibit exchange bias as well as vertical asymmetry which could be\nbecause of spin pinning at the boundaries between ferromagnetic and\nantiferromagnetic domains. Interestingly, like in bulk BiFeO_3, both the\ncalorimetric and dielectric permittivity data in nanoscale BiFeO_3 exhibit\ncharacteristic features at the magnetic transition point. These features\nestablish formation of a true ferromagnetic-ferroelectric system with a\ncoupling between the respective order parameters in nanoscale BiFeO_3."
    },
    {
        "anchor": "Assessment of valley coherence in a high-quality monolayer molybdenum\n  diselenide: We investigate the valley coherence in high and low-quality monolayer MoSe2\nby polarization-resolved photoluminescence spectroscopy. The observed valley\ncoherence is on the order of 10 % regardless of the sample quality, proving\nthat the suppression of extrinsic effects does not improve the valley\ncoherence. The valley decoherence time estimated based on the valley coherence\ntime and exciton lifetime is sub-picosecond at the longest, which suggests that\nintrinsic scattering sources, such as phonons, strongly limit the valley\ncoherence.",
        "positive": "Thermoelectric Properties of\n  (1-x)LaCoO$_{3.x}$La$_{0.7}$Sr$_{0.3}$MnO$_3$ Composite: We report the thermoelectric (TE) properties of (1-x)LaCoO3.xLa0.7Sr0.3MnO3\n(0 < x < 0.10) composite in a temperature range 320-800 K. Addition of\nLa0.7Sr0.3MnO3 to LaCoO3 in small amount (5 weight %) improves the overall\nSeebeck coefficient ({\\alpha}) at higher temperatures. The electrical\nconductivity, however, decreases due to a decrease in carrier concentration of\nthe composite. The decrease in electrical conductivity of the composite at high\ntemperature may be attributed to the insulating nature of the LSMO above room\ntemperature. Thermal conductivity (\\k{appa}) of all the samples increases with\nan increase in the temperature but decreases with increasing LSMO content. We\nalso report the local variation of the Seebeck coefficient across the composite\nsamples measured using a precision Seebeck measurement system. A maximum value\nof 0.09 for the figure of merit (ZT) is obtained for\n0.95LaCoO3.0.05La0.7Sr0.3MnO3 at 620 K which is significantly higher than the\nZT of either of LaCoO3 or La0.7Sr0.3MnO3 at 620 K. This suggests the potential\nfor enhancement of operating temperatures of hitherto well known\nlow-temperature thermoelectric materials through suitable compositing approach."
    },
    {
        "anchor": "Nonequilibrium Lattice Dynamics in Monolayer MoS2: The coupled nonequilibrium dynamics of electrons and phonons in monolayer\nMoS2 is investigated by combining first-principles calculations of the\nelectron-phonon and phonon-phonon interaction with the time-dependent Boltzmann\nequation. Strict phase-space constraints in the electron-phonon scattering are\nfound to influence profoundly the decay path of excited electrons and holes,\nrestricting the emission of phonons to crystal momenta close to few\nhigh-symmetry points in the Brillouin zone. As a result of momentum selectivity\nin the phonon emission, the nonequilibrium lattice dynamics is characterized by\nthe emergence of a highly-anisotropic population of phonons in reciprocal\nspace, which persists for up to 10 ps until thermal equilibrium is restored by\nphonon-phonon scattering. Achieving control of the nonequilibrium dynamics of\nthe lattice may provide unexplored opportunities to selectively enhance the\nphonon population of two-dimensional crystals and, thereby, transiently tailor\nelectron-phonon interactions over sub-picosecond time scales.",
        "positive": "Cyclic Strength and Nonlinear Material Fracture Mechanics (by the\n  example of steels): It was shown that a material fatigue fracture diagram can be viewed as a\nlocus of points with $\\sigma $ and $\\sqrt l$ coordinates' product equal to\n$K_{1c}/2$, and $\\sigma $ and $l$ product -- to $G_{1c}/2$, where $K_{1c}$ and\n$G_{1c}$ are non-linear fracture mechanics force and energy criteria. It was\nestablished that the average number of interatomic bonds destroyed within one\nalternate stress $\\nabla_{1cs}$ cycle is directly proportional to $\\sigma $\nthat is twice as large as a peak value of $\\sigma^a$. It was found that\nlow-cycle fatigue is characterized by $\\sigma >\\sigma_{0.2}$ and $\\sigma_{1cs}>\n1$, high-cycle fatigue -- by $\\sigma = \\sigma_{0.2}$ and $\\nabla_{1cs} = 1$,\nand giga-cycle fatigue -- by $\\sigma < \\sigma_{0.2}$ and $\\nabla_{1cs} < 1$. An\nindividual interatomic bond cannot be destroyed part by part but as a single\nunit. The latter means that in giga-cycle fatigue a single interatomic bond is\ndestroyed within several cycles rather than within a single cycle. The factors\n$F$ (collapsibility) and $R$ (resistibility) were proposed and mentioned as\nessential material physical constants. The introduced notion $\\nabla_{1cs}$ and\nthe established linear nature of $\\nabla_{1cs}$ relationship allow to: a)\nclarify the fatigue crack growth physical nature in low-, high- and giga-cycle\nfracture zones; b) determine the nature of a fatigue fracture diagram\ndisruption; c) plot the fatigue fracture diagram using the results obtained in\na single specimen cyclic strength test with a selected value of $\\sigma \\ge\n\\sigma_{0.2}$. For giga-cycle fatigue it is important (with similar purpose in\nmind) to determine this dependence for $\\sigma < \\sigma_{0.2}$. It is\nrecommended to use $G_{1c}$ criterion to find the $l_{cr}$ length value which\nin contrast to $K_{1c}$ has a clear physical nature."
    },
    {
        "anchor": "Structural investigation of (111) oriented\n  (BiFeO3)(1-x)\u039b/(LaFeO3)x\u039b superlattices by X-ray diffraction\n  and Raman spectroscopy: (BiFeO3)(1-x){\\Lambda}/(LaFeO3)x{\\Lambda} superlattices (SLs) with varying x\nhave been grown by pulsed laser deposition on (111) oriented SrTiO3 substrates.\nIn order to obtain good epitaxy and flat samples a conducting SrRuO3 buffer has\nbeen deposited prior to the superlattices to screen the polar mismatch for such\n(111) SrTiO3 orientation. X-ray diffraction reciprocal space mapping on\ndifferent family of planes were collected and evidenced a room temperature\nstructural change at x=0.5 from a rhombohedral/monoclinic structure for rich\nBiFeO3 to an orthorhombic symmetry for rich LaFeO3. This symmetry change has\nbeen confirmed by Raman spectroscopy and demonstrates the different phase\nstability compared to similar SLs grown on (100) SrTiO3. The strongly\nanisotropic strain and oxygen octahedral rotation/tilt system compatibility at\nthe interfaces probably explain the orientation dependence of the phase\nstability in such superlattices.",
        "positive": "Phonon-lithium ion interactions: A case study of LiM(SeO3)2: Li ion diffusion is fundamentally a thermally activated ion hopping process.\nRecently, soft lattice, anharmonic phonon and paddlewheel mechanism have been\nproposed to potentially benefit the ion transport, while the understanding of\nvibrational couplings of mobile ion and anions is still limited but essential.\nHerein, we access the ionic conductivity, the stability and the lattice\ndynamics in LiM(SeO3)2 (M =Al, Ga, In, Sc, Y, and La) with two types of oxygen\nanions within LiO4 polyhedron, namely edge-shared and corner-shared, the\nprototype of which, LiGa(SeO3)2, has been experimentally synthesized. We\nstudied in detail the anharmonic and harmonic phonon interactions, as well as\ncouplings between vibrations of edge-bonded or corner-bonded anions in Li\npolyanions and Li ion diffusion. As M changing from Sc to La, anharmonic\nphonons increase alongside reduced activation energy for Li diffusion. Phonon\nmodes involving edge-bonded oxygen anions contribute more to Li migration than\ncorner-bonded oxygen anions, owing to greater atomic interactions between Li\nions and edge-bonded anions. Thus, rather than the overall lattice softness,\nattentions shall be paid to reduce the frequency of the critical phonons\ncontributing to Li ion diffusions as well as to increase the anharmonicity, for\nthe design of Li ion superionic conductors for all-solid-state-batteries."
    },
    {
        "anchor": "Z$_2$ topological number of local quantum clusters in the orthogonal\n  dimer model: We have studied the $Z_2$ topological number defined by the Berry phase for\nthe gapped frustrated systems including the orthogonal dimer model which has a\ndirect product state of local quantum clusters as the exact ground state. The\n$Z_2$ topological number can clarify what kind of the local quantum clusters is\nformed to lift the macroscopic degeneracy due to frustration, even when the\nexact ground state is unknown. As a demonstration, the dimer-singlet and\nplaquette-singlet phase are identified by two kinds of Z$_2$ topological\nnumbers in the Shastry-Sutherland model and its generalization realized\nexperimentally as SrCu$_2$(BO$_3$)$_2$ and CaV$_4$O$_9$.",
        "positive": "Magnetoelastic mechanism of spin-reorientation transitions at step-edges: The symmetry-induced magnetic anisotropy due to monoatomic steps at strained\nNi films is determined using results of first - principles relativistic\nfull-potential linearized augmented plane wave (FLAPW) calculations and an\nanalogy with the N\\'eel model. We show that there is a magnetoelastic\nanisotropy contribution to the uniaxial magnetic anisotropy energy in the\nvicinal plane of a stepped surface. In addition to the known spin-direction\nreorientation transition at a flat Ni/Cu(001) surface, we propose a\nspin-direction reorientation transition in the vicinal plane for a stepped\nNi/Cu surface due to the magnetoelastic anisotropy. We show that with an\nincrease of Ni film thickness, the magnetization in the vicinal plane turns\nperpendicular to the step edge at a critical thickness calculated to be in the\nrange of 16-24 Ni layers for the Ni/Cu(1,1,13) stepped surface."
    },
    {
        "anchor": "Atomistic Modelling of Functionally Graded Cu-Ni Alloy and its\n  Implication on the Mechanical Properties of Nanowires: Functionally graded materials (FGM) eliminate the stress singularity in the\ninterface between two different materials and therefore have a wide range of\napplications in high temperature environments such as engines, nuclear\nreactors, spacecrafts etc. Therefore, it is essential to study the mechanical\nproperties of different FGM materials. This paper aims at establishing a method\nfor modelling FGMs in molecular dynamics (MD) to get a better insight of their\nmechanical properties. In this study, the mechanical characteristics of Cu-Ni\nFGM nanowires (NW) under uniaxial loading have been investigated using the\nproposed method through MD simulations. In order to describe the inter-atomic\nforces and hence predict the properties properly, EAM (Embedded atom model)\npotential has been used. The nanowire is composed of an alloying constituent in\nthe core and the other constituent graded functionally along the outward radial\ndirection. Simple Linear and Exponential functions have been considered as the\nfunctions which defines the grading pattern. The alloying percentage on the\nsurface has been varied from 0% to 50% for both Cu-cored and Ni-cored\nnanowires. All the simulations have been carried out at 300 K. The L/D ratios\nare 10.56 and 10.67 for Cu-cored and Ni-cored NWs, respectively. This study\nsuggests that Ultimate Tensile Stress and Young's modulus increase with\nincreasing surface Ni percentage in Cu-cored NWs. However, in Ni-cored NWs\nthese values decrease with the increase of surface Cu percentage. Also, for the\nsame surface percentage of Ni in Cu-cored NW, the values are higher in linearly\ngraded FGMs than that in exponentially graded FGMs. While in Ni-cored NWs,\nexponentially graded FGM shows higher values of UTS and E than those in\nlinearly graded FGM. Thus, grading functions and surface percentages can be\nused as parameters for modulating the mechanical properties of FGM nanowires.",
        "positive": "Interaction potential of FePt with the MgO(001) surface: By means of density functional theory we have undertaken a structural,\nelectronic and magnetic survey of the adsorption of the Fe_xPt_y(x,y=<4)\nclusters on MgO (001) surface under the generalized gradient approximation. We\nhave tested different atomic adsorption geometries with the aim of scan a wider\nrange of adsorption sites in order to determine the preferential surface\ncovering. Our main conclusion in this respect is that the FePt wets the\nsurface. The intracluster (before and after the adsorption) and\ncluster-to-surface binding mechanisms were investigated via the adsorption\nenergy, charge transfer, density of states and hybridization analysis. The\nadsorption energy values increased for those geometries in which keeping the Fe\nor Pt atom @top-O, the outermost species was moved to cover the surface. In\ngeneral the unsupported clusters present higher intracluster energies than the\nadsorbed ones being the average difference of 1.5 eV. In this regard there was\na small reduction in the net magnetic moment of the supported clusters due to\nan internal and external rearrangement of the spin-up/-down charge.\nFurthermore, a complex and subtle charge transfer between different species\ntakes place having an increasing the Pt and O population at the expense of the\nlost Fe charge."
    },
    {
        "anchor": "Conductive Domain Walls in Non-Oxide Ferroelectrics Sn2P2S6: The conductive domain wall (CDW) is extensively investigated in\nferroelectrics, which can be considered as a quasi-two-dimensional\nreconfigurable conducting channel embedded into an insulating material.\nTherefore, it is highly important for the application of ferroelectric\nnanoelectronics. Hitherto, most CDW investigations are restricted in oxides,\nand limited work has been reported in non-oxides to the contrary. Here, by\nsuccessfully synthesizing the non-oxide ferroelectric Sn2P2S6 single crystal,\nwe observed and confirmed the domain wall conductivity by using different\nscanning probe techniques which origins from the nature of inclined domain\nwalls. Moreover, the domains separated by CDW also exhibit distinguishable\nelectrical conductivity due to the interfacial polarization charge with\nopposite signs. The result provides a novel platform for understanding\nelectrical conductivity behavior of the domains and domain walls in non-oxide\nferroelectrics.",
        "positive": "Nexus networks in carbon honeycombs: Nexus metals represent a new type of topological material in which nodal\nlines merge at nexus points. Here, we propose novel networks in nexus systems\nthrough intertwining between nexus fermions and additional nodal lines. These\nnexus networks can be realized in several recently synthesized carbon honeycomb\nmaterials. In these carbon honeycombs, we demonstrate a phase transition\nbetween a nexus network and a system with triply-degenerate points and\nadditional nodal lines. The Landau level spectra show unusual magnetic\ntransport properties in the nexus networks. Our results pave the way toward\nrealizations of new topological materials with novel transport properties\nbeyond standard Weyl/Dirac semimetals."
    },
    {
        "anchor": "Dual modulation STM: Simultaneous high-resolution mapping of the\n  differential conductivity and local tunnel barrier height demonstrated on\n  Au(111): We present a scanning tunneling microscopy (STM) technique to simultaneously\nmeasure the topography, the local tunnel barrier height (dI/dz) and the\ndifferential conductivity (dI/dV). We modulate the voltage and tip piezo with\nsmall sinusoidal signals that exceed the cut-off frequency of the STM\nelectronics and feed the tunneling current into two lock-in amplifiers (LIAs).\nWe derive and follow a set of criteria for the modulation frequencies to avoid\nany interference between the LIA measurements. To validate the technique, we\nmeasure Friedel oscillations and the subtle tunnel barrier difference between\nthe hcp and fcc stacked regions of the Au(111) herringbone reconstruction.\nFinally, we show that our method is also applicable to open feedback loop\nmeasurements by performing grid I(V) spectroscopy.",
        "positive": "Computing solubility and thermodynamics properties of H2O2 in water: Hydrogen peroxide plays a key role in many environmental and industrial\nchemical processes. We performed classical Molecular Dynamics and Continuous\nFractional Component Monte Carlo simulations to calculate thermodynamic\nproperties of H2O2 in aqueous solutions. The quality of the available force\nfields for H2O2 developed by Orabi & English, and by Cordeiro was\nsystematically evaluated. To assess which water force field is suitable for\npredicting properties of H2O2 in aqueous solutions, four water force fields\nwere used, namely the TIP3P, TIP4P/2005, TIP5P-E, and a modified TIP3P force\nfield. While the computed densities of pure H2O2 in the temperature range of\n253-353 K using the force field by Orabi & English are in excellent agreement\nwith experimental results, the densities using the force field by Cordeiro are\nunderestimated by 3%. The TIP4P/2005 force field in combination with the H2O2\nforce field developed by Orabi & English can predict the densities of H2O2\naqueous solution for the whole range of H2O2 mole fractions in very good\nagreement with experimental results. The TIP4P/2005 force field in combination\nwith either of the H2O2 force fields can predict the viscosities of H2O2\naqueous solutions for the whole range of H2O2 mole fractions in good agreement\nwith experimental results. The diffusion coefficients for H2O2 and water\nmolecules using the TIP4P/2005 force field with either of the H2O2 force fields\nare almost constant for the whole range of H2O2 mole fractions. The Cordeiro\nforce field for H2O2 in combination with either of the water force fields can\npredict the Henry coefficients of H2O2 in water in better agreement with\nexperimental values than the force field by Orabi & English."
    },
    {
        "anchor": "Modeling Dislocation Dynamics Data Using Semantic Web Technologies: Research in the field of Materials Science and Engineering focuses on the\ndesign, synthesis, properties, and performance of materials. An important class\nof materials that is widely investigated are crystalline materials, including\nmetals and semiconductors. Crystalline material typically contains a distinct\ntype of defect called \"dislocation\". This defect significantly affects various\nmaterial properties, including strength, fracture toughness, and ductility.\nResearchers have devoted a significant effort in recent years to understanding\ndislocation behavior through experimental characterization techniques and\nsimulations, e.g., dislocation dynamics simulations. This paper presents how\ndata from dislocation dynamics simulations can be modeled using semantic web\ntechnologies through annotating data with ontologies. We extend the already\nexisting Dislocation Ontology by adding missing concepts and aligning it with\ntwo other domain-related ontologies (i.e., the Elementary Multi-perspective\nMaterial Ontology and the Materials Design Ontology) allowing for representing\nthe dislocation simulation data efficiently. Moreover, we show a real-world use\ncase by representing the discrete dislocation dynamics data as a knowledge\ngraph (DisLocKG) that illustrates the relationship between them. We also\ndeveloped a SPARQL endpoint that brings extensive flexibility to query\nDisLocKG.",
        "positive": "Grain-level effects on in-situ deformation-induced phase transformations\n  in a complex-phase steel using 3DXRD and EBSD: A novel complex-phase steel alloy is conceived with a deliberately unstable\naustenite, $\\gamma$, phase that enables the deformation-induced martensitic\ntransformations (DIMT) to be explored at low levels of plastic strain. The DIMT\nwas thus explored, in-situ and non-destructively, using both far-field\nThree-Dimensional X-Ray Diffraction (3DXRD) and Electron Back-Scatter\nDiffraction (EBSD). Substantial $\\alpha'$ martensite formation was observed\nunder 10% applied strain with EBSD, and many $\\varepsilon$ grain formation\nevents were captured with 3DXRD, indicative of the indirect transformation of\nmartensite via the reaction $\\gamma \\rightarrow \\varepsilon \\rightarrow\n\\alpha'$. Using $\\varepsilon$ grain formation as a direct measurement of\n$\\gamma$ grain stability, the influence of several microstructural properties,\nsuch as grain size, orientation and neighbourhood configuration, on $\\gamma$\nstability have been identified. Larger $\\gamma$ grains were found to be less\nstable than smaller grains. Any $\\gamma$ grains oriented with {100} parallel to\nthe loading direction preferentially transformed with lower stresses. Parent\n$\\varepsilon$-forming $\\gamma$ grains possessed a neighbourhood with increased\nferritic/martensitic volume fraction. This finding shows, unambiguously, that\n$\\alpha$/$\\alpha'$ promotes $\\varepsilon$ formation in neighbouring grains. The\nminimum strain work criterion model for $\\varepsilon$ variant prediction was\nalso evaluated, which worked well for most grains. However,\n$\\varepsilon$-forming grains with a lower stress were less well predicted by\nthe model, indicating crystal-level behaviour must be considered for accurate\n$\\varepsilon$ formation. The findings from this work are considered key for the\nfuture design of alloys where the deformation response can be controlled by\ntailoring microstructure and local or macroscopic crystal orientations."
    },
    {
        "anchor": "Light-induced magnetization precession in GaMnAs: We report dynamics of the transient polar Kerr rotation (KR) and of the\ntransient reflectivity induced by femtosecond laser pulses in ferromagnetic\n(Ga,Mn)As with no external magnetic field applied. It is shown that the\nmeasured KR signal consist of several different contributions, among which only\nthe oscillatory signal is directly connected with the ferromagnetic order in\n(Ga,Mn)As. The origin of the light-induced magnetization precession is\ndiscussed and the magnetization precession damping (Gilbert damping) is found\nto be strongly influenced by annealing of the sample.",
        "positive": "n-type conversion of SnS by isovalent ion substitution: Geometrical\n  doping as a new doping route: Tin monosulfide (SnS) is a naturally p-type semiconductor with a layered\ncrystal structure, but no reliable n-type SnS has been obtained by conventional\naliovalent ion substitution. In this work, carrier polarity conversion to\nn-type was achieved by isovalent ion substitution for polycrystalline SnS thin\nfilms on glass substrates. Substituting Pb2+ for Sn2+ converted the majority\ncarrier from hole to electron, and the free electron density ranged from 1012\nto 1015 cm-3 with the largest electron mobility of 7.0 cm2/(Vs). The n-type\nconduction was confirmed further by the position of the Fermi level (EF) based\non photoemission spectroscopy and electrical characteristics of pn\nheterojunctions. Density functional theory calculations reveal that the Pb\nsubstitution invokes a geometrical size effect that enlarges the interlayer\ndistance and subsequently reduces the formation energies of Sn and Pb\ninterstitials, which work as electron donors."
    },
    {
        "anchor": "Thermodynamic origin of solute-enriched stacking-fault in dilute Mg-Zn-Y\n  alloys: We investigate thermodynamic behaviors of dilute Mg-Zn-Y ternary alloys to\nform a unique solute-enriched stacking-fault (SESF), which is an intrinsic-II\ntype stacking-fault (I2-SF) enriched by the Zn and Y atoms and represents the\nstructural-unit of the long-period stacking/order (LPSO) phase. SESF in the\nhexagonal-close-packed (hcp) Mg matrix forms a local face-centered-cubic (fcc)\nenvironment, and hence our thermodynamic analysis is based on the Gibbs energy\ncomparison between hcp and fcc phases over the Mg-Zn-Y ternary composition\nranges, using the calculation of phase diagrams (CALPHAD) method aided by the\nfirst principles calculations. Segregation behaviors of solute Zn/Y atoms into\nthe SESF are firstly estimated according to the Hillert's parallel tangent law,\nfollowed by the possible disorder-order phase transformation within the SESF\nusing the multiple-sublattice model. We find that the Zn/Y co-segregations at\nthe SESF provide a remarkable condition that the fcc layers become more stable\nthan the hcp-Mg matrix. Besides, within the SESF, the following spinodal-like\ndecomposition into the Mg-rich solid-solution and the Zn/Y-rich L12-type order\nphase causes a significant reduction of the total Gibbs energy of the system.\nThese thermodynamic behaviors explain fairly well a phenomenological origin of\nthe Zn-Y clustering with the L12-type short-range order, which is known to\noccur for the LPSO phases and also confirmed for the present SESF by electron\nmicroscopy experiments. Therefore, strong Zn-Y interactions even in dilute\nconditions play a key role to stabilize firmly the SESF in the Mg-Zn-Y alloys.",
        "positive": "Giant magnetic pumping of photovoltage and photocurrent using dielectric\n  lossy material: The enhancement of photovoltage and photocurrent of material is fundamentally\nsignificant owing to the many interesting phenomena found and the potential\napplications. However, vast altering of magnitude-orders of photoelectricity\nhas been technologically challenging. Here we report two dielectric materials\nLi2ZnSiO4 and Li2SiO3 showing high photovoltage and photocurrent tunability.\nWhen magnetic field increasing from 0.00015T up to 0.44T,it is found that 3850%\nof photovoltage tunability and 3841 % of photocurrent tunability in Li2ZnSiO4 ,\nand 132.8% of photovoltage tunability and 132.5% of photocurrent tunability in\nLi2SiO3. A simple model that considers the effects of spin mixing/interaction\nand magnetically-tunable charge gradient is used to explain this interaction\nbetween magnetic field and the photoelectricity. This result indicates a\nmagnetic approach can be potentially used for energy efficiency."
    },
    {
        "anchor": "Pseudogap in the optical phonon spectra: The energy spectrum of the quantum Klein-Gordon lattice is computed\nnumerically for different nonlinear contributions to the Hamiltonian. In\nagreement with the studies on the effective Hubbard Hamiltonian for boson\nquasi-particles (see for instance Refs.\\onlinecite{AGRANOVICH,Eilbeck}) a\npairing of the phonon states is found when the nonlinearity of the lattice is\nsignificant. On the opposite, when the nonlinear contribution is weak or\nmoderate, which is common in materials the effective Hamiltonian is not\nappropriate because it neglects all the energy terms that do not conserve the\nboson number. Then for a realistic modelling of the hybridization between the\nfree phonon and the phonon bound pairs, the Klein-Gordon Hamiltonian is\nrequired since it is derived from the potential energy of the atoms and thus it\ndoes not involve any arbitrary quanta conservation. Actually, when the\nnonlinearity is weak we prove that the binding energy of the phonon bound pairs\nvanishes at the center of the lattice Brillouin zone whereas at the edge, it\nmay be comparable to the phonon band width.Consequently, the signature of a\nweak nonlinearity is found to be a pseudogap that opens in the spectrum region\nof the two phonon energy, at the edge of the lattice Brillouin zone. Our\nresults are shown to be valid for all the lattice dimensions and for some model\nparameters that are relevant for the optical phonon spectra.",
        "positive": "Macrosteps dynamics and the growth of crystals and epitaxial layers: Step pattern stability of the vicinal surfaces during growth was analyzed\nusing various surface kinetic models. It was shown that standard analysis of\nthe vicinal surfaces provides no indication on the possible step coalescence\nand therefore could not be used to elucidate macrostep creation during growth.\nA scenario of the instability, leading go macrostep creation was based on the\ndynamics of the step train. The critical is step motion at the rear of the\ntrain which leads to double and multiple step creation. The condition is that\nthe step density ratio in and out of the train lower than 2 prevents double\nstep formation irrespective of the kinetics. For higher step density ratio low\ndensity of the step promotes single step stability. Fast step kinetics from\nlower terrace stabilizes the single steps slow (high barrier) is promoting step\ncoalescence. The incorporation kinetics from upper terrace role is close to\nneutral. The creation of double step creates slow the step in front to\naccelerate and catch the previous double step while those behind catch up the\ndouble step creating multistep structure. The multistep are not mobile as the\nalimentation leads to emission of single step which moves forward. The final\nstructure consist of macrosteps and superterraces with the number of single\nsteps moving forward. Thus the single step motion is essential crystal growth\nmode despite the presence of the macrosteps. The macrostep are prone to\ncreation of the overhangs which results from surface dynamics coupling to\nimpingement from the mother phase. The angular preferential access of the bulk\nmaterial to the macrostep edge, leads to diffusive instability. Therefore it is\nexpected that harmful influence of the macrosteps by creation of inclusions and\ndislocation is stronger during growth from the liquid phase."
    },
    {
        "anchor": "Short-range antiferromagnetic interaction and spin-phonon coupling in\n  La2CoMnO6 double perovskite: Weak antiferromagnetic (AF) interaction in the ferromagnetic (FM) partially\nordered La2CoMnO6 (LCMO) was detected by Raman spectroscopy by monitoring\nspin-phonon coupling. Because of the sensibility to probe short-range disorder\nand lattice modifications, the Raman spectroscopy showed to be an useful tool\nto indicate less remarkable magnetic transitions in LCMO compound. Apart from\nthe expected spin-phonon coupling due to the long-range FM superexchange\n(Tc~230 K), phonons parameters pointed out an additional spin-phonon coupling\nrelated to the short-range AF interaction at Tc~135 K, which was not detected\nfrom the magnetic bulk response. These results reinforce the Raman spectroscopy\nas a powerful technique to detect antisite disorder into A2B'B\"O6 magnetic\ndouble perovskites, whose magnetic properties are driven by superexchange\ninteractions.",
        "positive": "Topographic and electronic structure of cleaved SrTiO3(001) surfaces: The topographic and electronic structure of cleaved SrTiO3(001) surfaces were\nstudied, employing samples that either had or had not been coated with Ti on\ntheir outer surfaces prior to fracture. In both cases, SrO- and TiO2-terminated\nterraces were present on the cleavage surface, enabling in situ studies on\neither termination. However, the samples coated with Ti prior to fracture were\nfound to yield a rougher morphology on TiO2-terminated terraces as well as a\nhigher density of oxygen vacancies during an annealing (outgassing) step\nfollowing the coating. The higher density of oxygen vacancies in the bulk of\nthe Ti-coated samples also provides higher conductivity which, in turn,\nimproves a sensitivity of the spectroscopy and reduces the effect of\ntip-induced band bending. Nonetheless, similar spectral features, unique to\neach termination, were observed for samples both with and without the Ti\ncoating. Notably, with moderate-temperature annealing following fracture, a\nstrong discrete peak in the conductance spectra, arising from oxygen vacancies,\nwas observed on the SrO-terminated terraces. This peak appears at slightly\ndifferent voltages for coated and uncoated samples, signifying a possible\neffect of tip-induced band bending."
    },
    {
        "anchor": "Domain evolution in bended freestanding BaTiO3 ultrathin films: a\n  phase-field simulation: Perovskite ferroelectric oxides are usually considered to be brittle\nmaterials, however, recent work [Dong et al., Science 366, 475 (2019)]\ndemonstrated the super-elasticity in the freestanding BaTiO3 thin films. This\nproperty may originate from the ferroelectric domain evolution during the\nbending, which is difficult to observe in experiments. Therefore, understanding\nthe relation among the bending deformation, thickness of the films, and the\ndomain dynamics is critical for their potential applications in flexible\nferroelectric devices. Here, we reported the dynamics of ferroelectric\npolarization in the freestanding BaTiO3 ultrathin films in the presence of\nlarge bending deformation up to 40{\\deg} using phase-field simulation. The\nferroelectric domain evolution reveals the transition from the flux-closure to\na/c domains with \"vortex-like\" structures, which caused by the increase of\nout-of-plane ferroelectric polarization. Additionally, by varying the film\nthickness in the identical bending situation, we found the a/c phase with\n\"vortex-like\" structure emerges only as the film thickness reached 12 nm or\nhigher. Results from our investigations provide instructive information for the\nmicrostructure evolution of bending ferroelectric perovskite oxide films, which\ncould serve as guide for the future application of ferroelectric films on\nflexible electronic devices.",
        "positive": "Quantized Anomalous Hall Insulator in a Nanopatterned Two-Dimensional\n  Electron Gas: We propose that a quantum anomalous Hall insulator (QAHI) can be realized in\na nanopatterned two-dimensional electron gas (2DEG) with a small in-plane\nmagnetic field and a high carrier density. The Berry curvatures originating\nfrom the in-plane magnetic field and Rashba and Dresselhaus spin-orbit\ncoupling, in combination with a nanoscale honeycomb lattice potential\nmodulation, lead to topologically nontrivial insulating states in the 2DEG\nwithout Landau levels. In the bulk insulating gaps, the anomalous Hall\nconductivity is quantized $-e^{2}/h$, corresponding to a finite Chern number\n-1. There exists one gapless chiral edge state on each edge of a finite size\n2DEG."
    },
    {
        "anchor": "Argon difluoride stabilized at high pressure: On account of the rapid development of noble gas chemistry in the past\nhalf-century both xenon and krypton compounds can now be isolated in\nmacroscopic quantities. The same though does not hold true for the next lighter\ngroup 18 element, argon, which forms only isolated molecules stable solely in\nlow-temperature matrices or supersonic jet streams. Here we present theoretical\ninvestigations into a new high-pressure reaction pathway which enables\nsynthesis of Ar-bearing compounds in bulk and at room temperature.",
        "positive": "Phonon Band Structure and Thermal Transport Correlation in a Layered\n  Diatomic Crystal: To elucidate the relationship between a crystal's structure, its thermal\nconductivity, and its phonon dispersion characteristics, an analysis is\nconducted on layered diatomic Lennard-Jones crystals with various mass ratios.\nLattice dynamics theory and molecular dynamics simulations are used to predict\nthe phonon dispersion curves and the thermal conductivity. The layered\nstructure generates directionally dependent thermal conductivities lower than\nthose predicted by density trends alone. The dispersion characteristics are\nquantified using a set of novel band diagram metrics, which are used to assess\nthe contributions of acoustic phonons and optical phonons to the thermal\nconductivity. The thermal conductivity increases as the extent of the acoustic\nmodes increases, and decreases as the extent of the stop bands increases. The\nsensitivity of the thermal conductivity to the band diagram metrics is highest\nat low temperatures, where there is less anharmonic scattering, indicating that\ndispersion plays a more prominent role in thermal transport in that regime. We\npropose that the dispersion metrics (i) provide an indirect measure of the\nrelative contributions of dispersion and anharmonic scattering to the thermal\ntransport, and (ii) uncouple the standard thermal conductivity\nstructure-property relation to that of structure-dispersion and\ndispersion-property relations, providing opportunities for better understanding\nof the underlying physical mechanisms and a potential tool for material design."
    },
    {
        "anchor": "Efficient GW calculations via the interpolation of the screened\n  interaction in momentum and frequency space: The case of graphene: The GW self-energy may become computationally challenging to evaluate because\nof frequency and momentum convolutions. These difficulties were recently\naddressed by the development of the multipole approximation (MPA) and the W-av\nmethods: MPA accurately approximates full-frequency response functions using a\nsmall number of poles, while W-av improves the convergence with respect to the\nk-point sampling in 2D materials. In this work we (i) present a theoretical\nscheme to combine them, and (ii) apply the newly developed approach to the\nparadigmatic case of graphene. Our findings show an excellent agreement of the\ncalculated QP band structure with angle resolved photoemission spectroscopy\n(ARPES) data. Furthermore, the computational efficiency of MPA and W-av allows\nus to explore the logarithmic renormalization of the Dirac cone. To this aim,\nwe develop an analytical model, derived from a Dirac Hamiltonian, that we\nparameterize using ab-initio data. The comparison of the models obtained with\nPPA and MPA results highlights an important role of the dynamical screening in\nthe cone renormalization.",
        "positive": "The influence of system dynamics on the frictional resistance: insights\n  from a discrete model: In order to examine the influence of system dynamics on sliding friction, we\nintroduce the so-called micro-walking machine. This model consists of a rigid\nbody with a number of elastic contact spots that is pulled by a constantly\nmoving base. The system slides with dry friction on a rigid substrate. The\nkinematic coupling of the rotation and the translation of the rigid body\nresults in varying normal and tangential forces at the contact spots. For\ncertain parameter ranges this leads to self-excited oscillations in the\nvertical direction. A particular dynamic mode occurs which is characterized by\na strong correlation between low or even zero normal forces and a fast forward\nmotion. This effect is referred to as micro-walking. In addition to an\nexperimental rig we use numerical integration and an extensive parameter study\nfor the analysis. In theory, the reduction of the frictional resistance reaches\nup to 98%. These results are confirmed by the experiments where the maximal\nreduction was 73%. Our model shows that micro-vibrations play an important role\nfor the dynamic influences on the frictional resistance of systems that exhibit\napparently smooth sliding. The identification of the critical parameter range\nenables the systematic control of frictional resistance through the adjustment\nof attributes such as geometry and stiffness. In addition, it is possible to\ndeduce guidelines for how tribological test rigs should be designed in order to\nget reliable results."
    },
    {
        "anchor": "Accurate projected augmented wave (PAW) datasets for rare-earth elements\n  (RE=La-Lu): We provide accurate projected augmented wave (PAW) datasets for rare-earth\n(RE) elements with some suggested Hubbard U values allowing efficient\nplane-wave calculations. Solid state tests of generated datasets were performed\non rare-earth nitrides. Through density of state (DOS) and equation of state\n(EoS) comparisons, generated datasets were shown to yield excellent results\ncomparable to highly accurate all-electron full-potential linearized augmented\nplane-wave plus local orbital (FLAPW+LO) calculations. Hubbard U values for\ntrivalent RE ions are determined according to hybrid functional calculations.\nWe believe that these new and open-source PAW datasets will allow further\nstudies on rare-earth materials.",
        "positive": "Twin Boundaries and Heat Capacity of a Crystal: The influence of twin boundaries on the heat capacity and diffuse scattering\nin a crystal is described within the framework of a macroscopic dynamic theory."
    },
    {
        "anchor": "Confined linear carbon chains: A route to bulk carbyne: The extreme instability and strong chemical activity of carbyne, the infinite\nsp1 hybridized carbon chain, are responsible for its low possibility to survive\nin ambient conditions. Therefore, much less has been possible to explore about\ncarbyne as compared to other novel carbon allotropes such as fullerenes,\nnanotubes and graphene. Although end-capping groups can be used to stabilize\ncarbon chains, length limitation is still a barrier for its actual production,\nand even more for applications. Here, we report a novel route for bulk\nproduction of record long acetylenic linear carbon chains protected by thin\ndouble-walled carbon nanotubes. A corresponding extremely high Raman band is\nthe first proof of a truly bulk yield formation of very long arrangements,\nwhich is unambiguously confirmed by transmission electron microscopy and\nnear-field Raman spectroscopy. Our production establishes a way to\nexceptionally long stable carbon chains including more than 2300 carbon atoms,\nand an elegant forerunner towards the final goal of a bulk production of\nessentially infinite carbyne.",
        "positive": "Gas condensation within a bundle of carbon nanotubes - effects of\n  screening: We study the low temperature phase behavior of hydrogen within a bundle of\ncarbon nanotubes. Because the carbon environment weakens the attraction between\nmolecules within the same interstitial channel (IC), the ground state of the\none-dimensional (1D) system is an uncondensed gas. When the screened attractive\ninteraction between molecules in adjacent ICs is taken into account, the\nhydrogen ground state is a quasi-1D liquid. The critical temperature of this\nsystem is estimated."
    },
    {
        "anchor": "Current-induced domain wall motion with adiabatic spin torque only in\n  cylindrical nanowires: We investigate current-driven domain wall (DW) propagation in magnetic\nnanowires in the framework of the modified Landau-Lifshitz-Gilbert equation\nwith both adiabatic and nonadiabatic spin torque (NAST) terms. Contrary to the\ncommon opinion that NAST is indispensable for DW motion[1,2], we point out that\nadiabatic spin torque (AST) only is enough for current-driven DW motion in a\ncylindrical (uniaxial) nanowire. Apart from a discussion of the rigid DW motion\nfrom the energy and angular momentum viewpoint, we also propose an experimental\nscheme to measure the spin current polarization by combining both field and\ncurrent driven DW motion in a flat (biaxial) wire.",
        "positive": "Large modulation of thermal transport in 2D semimetal triphosphides by\n  doping-induced electron-phonon coupling: Recent studies demonstrate that novel 2D triphosphides semiconductors possess\nhigh carrier mobility and promising thermoelectric performance, while the\ncarrier transport behaviors in 2D semimetal triphosphides have never been\nelucidated before. Herein, using the first-principles calculations and\nBoltzmann transport theory, we reveal that the electron-phonon coupling can be\nsignificant and thus greatly inhibits the electron and phonon transport in\nelectron-doped BP3 and CP3. The intrinsic heat transport capacity of flexural\nacoustic phonon modes in the wrinkle structure is largely suppressed arising\nfrom the strong out-of-plane phonon scatterings, leading to the low phonon\nthermal conductivity of 1.36 and 5.33 W/(mK) for BP3 and CP3 at room\ntemperature, and at high doping level, the enhanced scattering from electron\ndiminishes the phonon thermal conductivity by 71% and 54% for BP3 and CP3,\nrespectively. Instead, electron thermal conductivity shows nonmonotonic\nvariations with the increase of doping concentration, stemming from the\ncompetition between electron-phonon scattering rates and electron group\nvelocity. It is worth noting that the heavy-doping effect induced strong\nscattering from phonon largely suppresses the electron transport and reduces\nelectron thermal conductivity to the magnitude of phonon thermal conductivity.\nThis work sheds light on the electron and phonon transport properties in\nsemimetal triphosphides monolayer and provides an efficient avenue for the\nmodulation of carrier transport by doping-induced electron-phonon coupling\neffect."
    },
    {
        "anchor": "Rheology of carbon nanotube dispersions: We report on rheological properties of a dispersion of multi-walled carbon\nnanotubes in a viscous polymer matrix. Particular attention is paid to the\nprocess of nanotubes mixing and dispersion, which we monitor by the rheological\nsignature of the composite. The response of the composite as a function of the\ndispersion mixing time and conditions indicates that a critical mixing time t*\nneeds to be exceeded to achieve satisfactory dispersion of aggregates, this\ntime being a function of nanotube concentration and the mixing shear stress. At\nshorter times of shear mixing, t<t*, we find a number of non-equilibrium\nfeatures characteristic of colloidal glass and jamming of clusters. A\nthoroughly dispersed nanocomposite, at t>t*, has several universal rheological\nfeatures; at nanotube concentration above a characteristic value ~2-3wt% the\neffective elastic gel network is formed, while the low-concentration composite\nremains a viscous liquid. We use this rheological approach to determine the\neffects of aging and re-aggregation.",
        "positive": "Tantalum nitride nanotube photoanodes: establishing a beneficial\n  back-contact by lift-off and transfer to titanium nitride layer: In this work we introduce the use of TiN/Ti2 N layers as a back contact for\nlifted-off membranes of anodic Ta3N5 nanotube layers. In photoelectrochemical\nH2 generation experiments under simulated AM 1.5G light, shift of the onset\npotential for anodic photocurrents to lower potentials is observed, as well as\na higher magnitude of the photocurrents compared to conventional Ta3N5\nnanotubes (~ 0.5 V RHE ). We ascribe this beneficial effect to the improved\nconductive properties of the TiNx -based back contact layer that enables a\nfacilitated electron-transport for tantalum-nitride based materials to the\nconductive substrate."
    },
    {
        "anchor": "Excitonic emission in van-der-Waals nanotubes of transition metal\n  dichalcogenides: Nanotubes (NTs) of transition metal dichalcogenides (TMDs), such as MoS2 and\nWS2, were first synthesized more than a quarter of a century ago; nevertheless,\nmany of their properties have so far remained basically unknown. This review\npresents the state of the art in the knowledge of the optical properties of TMD\nNTs. We first evaluate general properties of multilayered TMD crystals, and\nanalyze available data on electronic band structure and optical properties of\nrelated NTs. Then, the technology for the formation and the structural\ncharacteristics of TMD NTs are represented, focusing on the structures\nsynthesized by chemical transport reaction. The core of this work is the\npresentation of the ability of TMD NTs to emit bright photoluminescence (PL),\nwhich has been discovered recently. By means of micro-PL spectroscopy of\nindividual tubes we show that excitonic transitions relevant to both direct and\nindirect band gaps contribute to the emission spectra of the NTs despite the\npresence of dozens of monolayers in their walls. We highlight the performance\nof the tubes as efficient optical resonators, whose confined optical modes\nstrongly affect the emission bands. Finally, a brief conclusion is presented,\nalong with an outlook of the future studies of this novel member of the family\nof radiative NTs, which have unique potential for different nanophotonics\napplications.",
        "positive": "Comment on \"Pt magnetic polarization on Y3Fe5O12 and magnetotransport\n  characteristics\": In a recent Letter [Y.M. Lu et al., Phys. Rev. Lett. 110, 147207 (2013)], Lu\net al. reported on \"ferromagneticlike transport properties\" of thin films of\nPt, deposited ex situ via sputtering on the ferrimagnetic insulator Y3Fe5O12.\nThe authors found a magnetoresistance in Pt displaying a hysteresis\ncorresponding to the coercive field of Y3Fe5O12, consistent with the findings\nof other groups. While the latter interpreted their data in terms of the\nrecently proposed spin-Hall magnetoresistance, Lu et al. attributed their\nobservation to a magnetic proximity effect. To support this interpretation,\nthey measured the X-ray magnetic circular dichroism (XMCD) at the Pt L2,3 edges\nfrom a Pt/Y3Fe5O12 sample with a Pt thickness of 1.5 nm and derived an average\ninduced magnetic moment of 0.054 Bohr magnetons per Pt atom. This is\ncontradictory to the results of our previous comprehensive XMCD study of three\ndifferent Pt/Y3Fe5O12 samples with Pt thicknesses of 3, 7, and 10 nm from which\nwe identified an upper limit of (0.003 +/- 0.001) Bohr magnetons per Pt\n[Gepr\\\"ags et al., Appl. Phys. Lett. 101, 262407 (2012), arXiv:1211.0916]."
    },
    {
        "anchor": "Separation of piezoelectric grain resonance and domain wall dispersion\n  in PZT ceramics: We report on the experimental investigation of a high-frequency\n  (1MHz - 1.8GHz) dielectric dispersion in unpoled and poled\n  Pb(Zr,Ti)O3 ceramics. Two overlapping loss peaks could be revealed in the\ndielectric spectrum. The linear dependence between the lower-frequency peak\nposition and average grain size D, which holds for D< 10mkm, indicates that the\ncorresponding polarization mechanism originates from piezoelectric resonances\nof grains. The intensity of the higher-frequency peak is drastically reduced by\npoling. It is thus proposed that this loss peak is related to domain-wall\ncontribution to the dielectric dispersion.",
        "positive": "First principles calculation of polarization induced interfacial charges\n  in GaN/AlN heterostructures: We propose a new method to calculate polarization induced interfacial charges\nin semiconductor heterostructures using classical electrostatics applied to\nreal-space band diagrams from first principles calculations and apply it to\nGaN/AlN heterostructures with ultrathin AlN layers (4-6 monolayers). We show\nthat the calculated electric fields and interfacial charges are independent of\nthe exchange-correlation functionals used (local-density approximation and\nhybrid functionals). We also find the calculated interfacial charge of (6.8 +/-\n0.4) x 10^13 cm-2 to be in excellent agreement with experiments and the value\nof 6.58 x 10^13 cm-2 calculated from bulk polarization constants, validating\nthe use of bulk constants even for very thin films."
    },
    {
        "anchor": "Effect of layer number and layer stacking registry on the formation and\n  quantification of defects in graphene: Correct defect quantification in graphene samples is crucial both for\nfundamental and applied re-search. Raman spectroscopy represents the most\nwidely used tool to identify defects in graphene. However, despite its extreme\nimportance the relation between the Raman features and the amount of defects in\nmultilayered graphene samples has not been experimentally verified. In this\nstudy we intentionally created defects in single layer graphene, turbostratic\nbilayer graphene and Bernal stacked bilayer graphene by oxygen plasma. By\nemploying isotopic labelling, our study reveals substantial differences of the\neffects of plasma treatment on individual layers in bilayer graphene with\ndifferent stacking orders. In addition Raman spectroscopy evidences scattering\nof phonons in the bottom layer by defects in the top layer for Bernal-stacked\nsamples, which can in general lead to overestimation of the number of defects\nby as much as a factor of two.",
        "positive": "2D Mn Doped MoS$_2$: An Efficient Electrocatalyst for Hydrogen Evolution\n  Reaction: Earth-abundant two-dimensional (2D) pristine transition metal dichalcogenides\n(TMDs) have emerged as a superlative class of materials for several\napplications in electronic devices, energy storage devices, gas sensing, etc.,\nand they have recently attracted great attention, owing to their good catalytic\nactivity and excellent stability toward electrochemical H2 Evolution Reaction\n(HER). Each individual layer of the TMDs consists of three atomic layers in\nwhich the transition metal is sandwiched by two chalcogens. To activate the\ninert basal plane of the pristine 2D TMDs, it is needed to create some defects\nor doping of some heteroatoms in the pristine TMDs. Phase engineering\ntechniques have been used to activate the basal plane of the 2D TMDs. In this\narticle, we have computationally developed 2D monolayer Mn-MoS$_2$ material and\nits application in HER. Stable S terminated edge of the MoS$_2$ shows low\ncatalytic activity due to its inert basal plane, so to exploit these edges for\nimproved performance we doped Mn in the pristine MoS$_2$ material. Using\ntrailblazing and state of the art first principles-based density functional\ntheory we performed methodical and rigorous inspection of electronic structures\nand properties of monolayer Mn doped MoS$_2$ to be a promising alternative to\nnoble metal-based catalysts for HER. Periodic 2D slab of Mn-MoS$_2$ was created\nto study the electronic properties and the reaction pathway occurring on the\nsurface of the material has been delved into by creating Mn$_1$Mo$_9$S$_{21}$\nmolecular cluster model. Our study reveals that the 2D Mn-MoS$_2$ monolayer\nbased catalyst follows the Volmer-Heyrovsky reaction with very low energy\nbarriers during the HER mechanism. This study is focused on designing a low\ncost and efficient electrocatalyst for HER by using earth abundant TMDs and\nlowering the activation barriers by scrutinizing the kinetics of the reaction\nfor reactivity."
    },
    {
        "anchor": "Phonon heat conduction in Al1-xScxN thin films: Aluminum scandium nitride alloy (Al1-xScxN) is regarded as a promising\nmaterial for high-performance acoustic devices used in wireless communication\nsystems. Phonon scattering and heat conduction processes govern the energy\ndissipation in acoustic resonators, ultimately determining their performance\nquality. This work reports, for the first time, on phonon scattering processes\nand thermal conductivity in Al1-xScxN alloys with the Sc content (x) up to\n0.26. The thermal conductivity measured presents a descending trend with\nincreasing x. Temperature-dependent measurements show an increase in thermal\nconductivity as the temperature increases at temperatures below 200K, followed\nby a plateau at higher temperatures (T> 200K). Application of a virtual crystal\nphonon conduction model allows us to elucidate the effects of boundary and\nalloy scattering on the observed thermal conductivity behaviors. We further\ndemonstrate that the alloy scattering is caused mainly by strain-field\ndifference, and less by the atomic mass difference between ScN and AlN, which\nis in contrast to the well-studied Al1-xGaxN and SixGe1-x alloy systems where\natomic mass difference dominates the alloy scattering. This work studies and\nprovides the quantitative knowledge for phonon scattering and the thermal\nconductivity in Al1-xScxN, paving the way for future investigation of materials\nand design of acoustic devices.",
        "positive": "Intrinsic Ferromagnetism in the Diluted Magnetic Semiconductor\n  Co:TiO$_2$: Here we present a study of magnetism in \\CTO\\ anatase films grown by pulsed\nlaser deposition under a variety of oxygen partial pressures and deposition\nrates. Energy-dispersive spectrometry and transition electron microscopy\nanalyses indicate that a high deposition rate leads to a homogeneous\nmicrostructure, while very low rate or postannealing results in cobalt\nclustering. Depth resolved low-energy muon spin rotation experiments show that\nfilms grown at a low oxygen partial pressure ($\\approx 10^{-6}$ torr) with a\nuniform structure are fully magnetic, indicating intrinsic ferromagnetism.\nFirst principles calculations identify the beneficial role of low oxygen\npartial pressure in the realization of uniform carrier-mediated ferromagnetism.\nThis work demonstrates that Co:TiO$_2$ is an intrinsic diluted magnetic\nsemiconductor."
    },
    {
        "anchor": "All-optical switching due to state-filling in quantum dots: We report all-optical switching due to state-filling in quantum dots (QDs)\nwithin a Mach-Zehnder Interferometric (MZI) switch. The MZI was fabricated\nusing InGaAsP/InP waveguides containing a single layer of InAs/InP QDs. A\n1530-1570 nm probe beam is switched by optical excitation of one MZI-arm from\nthe top. By exciting below the InGaAsP bandgap, we prove that the refractive\nindex nonlinearity is only due to the QDs. The switching efficiency is 2\nrad/(microW absorbed power). Probe wavelength insensitivity was obtained using\na broad distribution of QDs.",
        "positive": "A theoretical prediction on huge hole and electron mobilities of\n  6,6,18-graphdiyne nanoribbons: Two-dimensional 6,6,18-graphdiyne and the corresponding one-dimensional\nnanoribbons are investigated using crystal orbital method. Based on HSE06\nfunctional, the one-dimensional confinement increases the band gaps. With band\ngaps larger than 0.4 eV, thirty-three 6,6,18-graphdiyne nanoribbons have larger\nmajority carrier mobilities at room temperature than the highest value of\narmchair graphene nanoribbons. Unlike {\\gamma}-graphdiyne, 6,6,18-graphdiyne\nnanoribbons have both huge hole and electron mobilities, depending on whether\nthey are armchair or zigzag type. The huge mobilities are explained by crystal\norbital analysis. The superior capabilities of 6,6,18-graphdiyne nanoribbons\nmake them possible candidates for high speed electronic devices in\ncomplementary circuits."
    },
    {
        "anchor": "Octahedral tilting in Prussian blue analogues: Octahedral tilting is key to the structure and functionality of perovskites.\nHere we show how these distortions manifest in the related Prussian blue\nanalogues (PBAs): cyanide versions of double perovskites with formula\nA$_x$M[M$^{\\prime}$(CN)$_6$]$_{1-y}\\Box _y\\cdot n$H$_2$O (A = alkali metal, M\nand M$^{\\prime}$ = transition metals, $\\Box$ = vacancy/defect). Tilts are\nfavoured by high values of $x$ if A = Na or K, whereas the transition metals\nplay a less important role. External hydrostatic pressure can induce tilt\ntransitions nearly irrespective of the stoichiometry, whereas thermal\ntransitions are only reported for $x>1$. Interstitial water can alter the\ntransitions induced by a different stimulus, but (de)hydration \\textit{per se}\ndoes not lead to tilts. Implications for rational design of critical\nfunctionality -- including improper ferroelectricity and electrochemical\nperformance -- are discussed. The results are important for a fundamental\nunderstanding of phase transitions as well as for the development of functional\nmaterials based on PBAs.",
        "positive": "Flicker Noise in Bilayer Graphene Transistors: We present the results of the experimental investigation of the low -\nfrequency noise in bilayer graphene transistors. The back - gated devices were\nfabricated using the electron beam lithography and evaporation. The charge\nneutrality point for the fabricated transistors was around 10 V. The noise\nspectra at frequencies above 10 - 100 Hz were of the 1/f - type with the\nspectral density on the order of 10E-23 - 10E-22 A2/Hz at the frequency of 1\nkHz. The deviation from the 1/f spectrum at the frequencies below 10 -100 Hz\nindicates that the noise is of the carrier - number fluctuation origin due to\nthe carrier trapping by defects. The Hooge parameter of 10E-4 was extracted for\nthis type of devices. The gate dependence of the noise spectral density\nsuggests that the noise is dominated by the contributions from the ungated part\nof the device channel and by the contacts. The obtained results are important\nfor graphene electronic applications."
    },
    {
        "anchor": "Establishing Magnetic Coupling in Spin-crossover-2D Hybrid\n  Nanostructures via Interfacial Charge-transfer Interaction: Despite a clear demonstration of bistability in spin-crossover (SCO)\nmaterials, the absence of long-range magnetic order and poor electrical\nconductivity limit their prospect in spintronic and nanoelectronic\napplications. Intending to create hybrid devices made of spin-crossover\n(SCO)-2D architecture, here, we report an easily processable Fe-based SCO\nnanostructures grown on 2D reduced graphene oxide (rGO). The heterostructure\nshows enhanced cooperativity due to formation of interfacial charge transfer\ninduced inter-molecular interaction. The spin transition temperature is\ncontrolled by tuning the coverage area of SCO nanostructured networks over the\n2D surfaces, thus manipulating hysteresis (aka memory) of the heterostructure.\nThe enhanced magnetic coupling of the heterostructure leads to the spontaneous\nmagnetization states with a large coercive field of $\\sim$ 3000 Oe.\nAdditionally, the low conductivity of the pristine SCO nanostructures is\naddressed by encapsulating them on suitable 2D rGO template, enabling detection\nof magnetic bistable spin states during high-spin/low-spin conductance change.\nThis adds spin functionality in conductance switching for realizing hybrid 2D\nspintronic devices. Ab-inito calculations, on the experimentally proposed\nnanostructures, corroborate the enhanced magnetic interaction in the proposed\narchitecture facilitated by interfacial charge transfer and provide insights on\nthe microscopic mechanism.",
        "positive": "Using transmission Kikuchi diffraction to characterise \u03b1 variants\n  in an \u03b1 + \u03b2 titanium alloy: Two phase titanium alloys are important for high performance engineering\ncomponents, such as aeroengine discs. The microstructures of these alloys are\ntailored during thermomechanical processing to precisely control phase\nfactions, morphology and crystallographic orientations. In bimodal two phase\n({\\alpha} + {\\beta}) Ti-6Al-2Sn-4Zr-2Mo (Ti-6242) alloys there are often three\nmicrostructural lengthscales to consider: large (~10 {\\mu}m) equiaxed primary\n{\\alpha}; >200 nm thick plate {\\alpha} with a basketweave morphology; and very\nfine scaled (>50 nm plate thickness) secondary {\\alpha} that grows between the\nlarger {\\alpha} plates surrounded by retained {\\beta}. In this work, we utilise\nhigh spatial resolution transmission Kikuchi diffraction (TKD, also known as\ntransmission based electron backscatter diffraction, t-EBSD) and scanning\nelectron microscopy (SEM) based forward scattering electron imaging to resolve\nthe structures and orientations of basketweave and secondary {\\alpha} in\nTi-6242. We analyse the {\\alpha} variants formed within one prior {\\beta}\ngrain, and test whether existing theories of habit planes of the phase\ntransformation are upheld. Our analysis is important in understanding both the\nthermomechanical processing strategy of new bimodal two-phase titanium alloys,\nas well the ultimate performance of these alloys in complex loading regimes\nsuch as dwell fatigue. Our paper champions the significant increase in spatial\nresolution afforded using transmission techniques, combined with the ease of\nSEM based analysis using conventional electron backscatter diffraction (EBSD)\nsystems and forescatter detector (FSD) imaging, to study the nanostructure of\nreal-world engineering alloys."
    },
    {
        "anchor": "Wettability and \"petal effect\" of GaAs native oxides: We discuss unreported transitions of oxidized GaAs surfaces between\n(super)hydrophilic and hydrophobic states when stored in ambient conditions.\nContact angles higher than 90deg and high adhesive force were observed for\nseveral air-aged epitaxial samples grown under different conditions as well as\non epi-ready wafers. Regardless of the morphologies of the surface,\nsuperhydrophilicity of oxygen-plasma treated samples was observed, an effect\ndisappearing with storage time. Reproducible hydrophobicity was likewise\nobserved, as expected, after standard HCl surface etching. The relation between\nsurface oxides and hydrophobic/hydrophilic behavior is discussed.",
        "positive": "GaMnAs-based magnetic tunnel junctions with an AlMnAs barrier: We investigate the spin-dependent transport of GaMnAs-based magnetic tunnel\njunctions (MTJs) containing a paramagnetic AlMnAs barrier with various\nthicknesses. The barrier height of AlMnAs with respect to the Fermi level of\nGaMnAs is estimated to be 110 meV. We observe tunneling magnetoresistance (TMR)\nratios up to 175% (at 2.6 K), which is higher than those of the GaMnAs-based\nMTJs with other barrier materials in the same temperature region. These high\nTMR ratios can be mainly attributed to the relatively high crystal quality of\nAlMnAs and the suppression of the tunneling probability near at the in-plane\nwave-vector k||=0."
    },
    {
        "anchor": "Tuning the magnetic properties of Fe50-xMnxPt50 thin films: The magnetic and structural properties of highly ordered (S ~ 0.82) epitaxial\nFe50-xMnxPt50 thin films were investigated. We report the change in the\nmagnetic properties of Mn doped FePt epitaxial thin films. This study differs\nfrom the earlier experimental studies on Mn doped FePt based alloys. Ordered\nL10 Fe50-xMnxPt50 (x=0, 6, 9, 12 and 15) thin films with a constant thickness\nof 45 nm were prepared by co-sputtering Fe50Pt50 and Mn50Pt50 on to MgO (100)\nsingle crystal substrate. We find a significant increase in the coercivity for\nFe-Mn-Pt thin films. We have shown that this increase in magnetic properties\ncoincide with the tetragonal distortion, while the recent first principles\nstudy of Mn doped FePt showed the sub lattice ordering of ferromagnetically\naligned Mn atoms would lead to increase in magnetic properties in the FeMnPt\nternary alloy system with fixed Pt concentration. At x=12 the coercivity has\nincreased by 46.4 % when compared to Fe50Pt50. The increase in magnetic\nproperties in Fe50-xMnxPt50 is due to the tetragonal distortion as experimental\nc/a ratio is larger than the expected c/a ratio for ferromagnetically ordered\nMn atoms in the sublattice at the concentration x=12. Thus we show that high\ntemperature deposition and high temperature annealing is one of the methods to\nachieve large coercivity in Mn doped FePt as it leads to tetragonal distortion.",
        "positive": "Power loss of hot Dirac fermions in silicene and its near equivalence\n  with graphene: The power loss $P$ of hot Dirac fermions through the coupling to the\nintrinsic intravalley and intervalley acoustic and optical phonons is\nanalytically investigated in silicene as a function of electron temperature\n$T_e$ and density $n_s$. At very low $T_e$, the power dissipation is found to\nfollow the Bloch-Gr\\\"{u}neisen power-law $\\propto T_e^4$ and $n_s^{-0.5}$, as\nin graphene, and for $T_e \\lesssim20-30$ K, the power loss is predominantly due\nto the intravalley acoustic phonon scattering. On the other hand,\ndispersionless low energy intervalley acoustic phonons begin to dominate the\npower transfer at temperatures as low as $\\sim$$30$ K, and optical phonons\ndominate at $T_e \\gtrsim200$ K, unlike the graphene. The total power loss\nincreases with $T_e$ with a value of $\\sim$$10^{10}$ eV/s at $300$ K, which is\nthe same order of magnitude as in graphene. The power loss due to intravalley\nacoustic phonons increases with $n_s$ at higher $T_e$, whereas due to the\nintervalley acoustic and optical phonons is found to be independent of $n_s$.\nInterestingly, the energy relaxation time in silicene is about $4$ times higher\nthan that in graphene. For this reason, silicene may be superior over graphene\nfor its applications in bolometers and calorimeters. Power transfer to the\nsurface optical phonons $P_{\\text{SO}}$ is also studied as a function of $T_e$\nand $n_s$ for silicene on Al$_2$O$_3$ substrate and it is found to be greater\nthan the intrinsic phonon contribution at higher $T_e$. Substrate engineering\nis discussed to reduce $P_{\\text{SO}}$."
    },
    {
        "anchor": "Imaging and characterization of conducting ferroelectric domain walls by\n  photoemission electron microscopy: High-resolution X-ray photoemission electron microscopy (X-PEEM) is a\nwell-established method for imaging ferroelectric domain structures. Here, we\nexpand the scope of application of X-PEEM and demonstrate its capability for\nimaging and investigating domain walls in ferroelectrics with high-spatial\nresolution. Using ErMnO3 as test system, we show that ferroelectric domain\nwalls can be visualized based on photo-induced charging effects and local\nvariations in their electronic conductance can be mapped by analyzing the\nenergy distribution of photoelectrons. Our results open the door for\nnon-destructive, contract-free, and element-specific studies of the electronic\nand chemical structure at domain walls in ferroelectrics.",
        "positive": "Random-phase approximation and its applications in computational\n  chemistry and materials science: The random-phase approximation (RPA) as an approach for computing the\nelectronic correlation energy is reviewed. After a brief account of its basic\nconcept and historical development, the paper is devoted to the theoretical\nformulations of RPA, and its applications to realistic systems. With several\nillustrating applications, we discuss the implications of RPA for computational\nchemistry and materials science. The computational cost of RPA is also\naddressed which is critical for its widespread use in future applications. In\naddition, current correction schemes going beyond RPA and directions of further\ndevelopment will be discussed."
    },
    {
        "anchor": "Magnetic state electrical readout of Mn12 molecules: We demonstrate that the different magnetic states of a Mn12 molecule can be\ndistinguished in a two-probe transport experiment from a complete knowledge of\nthe current-voltage curve. Our results, obtained with state-of-the-art\nnon-equilibrium transport methods combined with density functional theory,\ndemonstrate that spin configuration-specific negative differential resistances\n(NDRs) appear in the I-V curves. These originate from the interplay between\nelectron localization and the re-hybridization of the molecular levels in an\nexternal electric field and allow the detection of the molecule's spin-state.",
        "positive": "Non-stoichiometry effects on the extreme magnetoresistance in Weyl\n  semimetal WTe2: Non-stoichiometry effect on the extreme magnetoresistance is systematically\ninvestigated for the Weyl semimetal WTe2. Magnetoresistance and Hall\nresistivity are measured for the as-grown samples with a slight difference in\nTe vacancies and the annealed samples with increased Te vacancies. The fittings\nto a two-carrier model show that the magnetoresistance is strongly dependent on\nthe residual resistivity ratio (i.e., the degree of non-stoichiometry), which\nis eventually understood in terms of electron doping which not only breaks the\nbalance between electron-type and hole-type carrier densities but also reduces\nthe average carrier mobility. Thus, compensation effect and ultrahigh mobility\nare probably the main driving force of the extreme magnetoresistance in WTe2."
    },
    {
        "anchor": "Stability of E' centers induced by 4.7eV laser radiation in SiO2: The kinetics of E' centers (silicon dangling bonds) induced by 4.7eV pulsed\nlaser irradiation in dry fused silica was investigated by in situ optical\nabsorption spectroscopy. The stability of the defects, conditioned by reaction\nwith mobile hydrogen of radiolytic origin, is discussed and compared to results\nof similar experiments performed on wet fused silica. A portion of E' and\nhydrogen are most likely generated by laser-induced breaking of Si-H\nprecursors, while an additional fraction of the paramagnetic centers arise from\nanother formation mechanism. Both typologies of E' participate to the reaction\nwith H_2 leading to the post-irradiation decay of the defects. This annealing\nprocess is slowed down on decreasing temperature and is frozen at T=200K,\nconsistently with the diffusion properties of H_2 in silica.",
        "positive": "Metacomposite characteristics and their influential factors of polymer\n  composites containing orthogonal ferromagnetic microwire arrays: The microwave properties of glass-fibers reinforced polymer composite\nembedded with an orthogonal array of Fe77Si10B10C3 microwires have been\ninvestigated. The composites containing orthogonal wire arrays display a\nremarkable transmission window in the frequency band of 1 to 6 GHz under zero\nexternal magnetic field indicating an intrinsic double-negative-index\ncharacteristic. The polymer matrices have proved to exert a synergistic effect\non the microwave properties, which is responsible for the disappearance of the\ntransmission windows when Ek is perpendicular to the glass fiber direction. The\nplasma frequency of the orthogonal microwire array composite is higher than\nthat of the parallel microwire array with identical wire spacing; this could be\nattributed to the enhanced microwire-wave interaction induced by the axial\nelectrical components on the additional layer of perpendicular wires. All these\nfeatures make this new kind of orthogonal microwire composites promising for\npotential cloaking and sensing applications."
    },
    {
        "anchor": "Submicrometric Films of Surface-Attached Polymer Network with\n  Temperature-Responsive Properties: Temperature-responsive properties of surface-attached\npoly(N-isopropylacrylamide) (PNIPAM) network films with well-controlled\nchemistry are investigated. The synthesis consists of cross-linking and\ngrafting preformed ene-reactive polymer chains through thiol--ene click\nchemistry. The formation of surface-attached and cross-linked polymer films has\nthe advantage of being wellcontrolled without any caution of no-oxygen\natmosphere or addition of initiators. PNIPAM hydrogel films with same\ncross-link density are synthesized on a wide range of thickness, from\nnanometers to micrometers. The swelling-collapse transition with temperature is\nstudied by using ellipsometry, neutron reflectivity, and atomic force\nmicroscopy as complementary surface-probing techniques. Sharp and high\namplitude temperature-induced phase transition is observed for all\nsubmicrometric PNIPAM hydrogel films. For temperature above LCST,\nsurface-attached PNIPAM hydrogels collapse similarly but without complete\nexpulsion of water. For temperature below LCST, the swelling of PNIPAM\nhydrogels depends on the film thickness. It is shown that the swelling is\nstrongly affected by the surface attachment for ultrathin films below $\\sim$150\nnm. For thicker films above 150 nm (to micrometers), surface-attached polymer\nnetworks with the same cross-link density swell equally. The density profile of\nthe hydrogel films in the direction normal to the substrate is confronted with\nin-plane topography of the free surface. It results that the free interface\nwidth is much larger than the roughness of the hydrogel film, suggesting\npendant chains at the free surface.",
        "positive": "Origin of the hump anomalies in the Hall resistance loops of ultrathin\n  SrRuO$_3$/SrIrO$_3$ multilayers: The proposal that very small N\\'eel skyrmions can form in SrRuO$_3$/SrIrO$_3$\nepitaxial bilayers and that the electric field-effect can be used to manipulate\nthese skyrmions in gated devices strongly stimulated the recent research of\nSrRuO$_3$ heterostructures. A strong interfacial Dzyaloshinskii-Moriya\ninteraction, combined with the breaking of inversion symmetry, was considered\nas the driving force for the formation of skyrmions in SrRuO$_3$/SrIrO$_3$\nbilayers. Here, we investigated nominally symmetric heterostructures in which\nan ultrathin ferromagnetic SrRuO$_3$ layer is sandwiched between large\nspin-orbit coupling SrIrO$_3$ layers, for which the conditions are not\nfavorable for the emergence of a net interfacial Dzyaloshinskii-Moriya\ninteraction. Previously the formation of skyrmions in the asymmetric\nSrRuO$_3$/SrIrO$_3$ bilayers was inferred from anomalous Hall resistance loops\nshowing humplike features that resembled topological Hall effect contributions.\nSymmetric SrIrO$_3$/SrRuO$_3$/SrIrO$_3$ trilayers do not show hump anomalies in\nthe Hall loops. However, the anomalous Hall resistance loops of symmetric\nmultilayers, in which the trilayer is stacked several times, do exhibit the\nhumplike structures, similar to the asymmetric SrRuO$_3$/SrIrO$_3$ bilayers.\nThe origin of the Hall effect loop anomalies likely resides in unavoidable\ndifferences in the electronic and magnetic properties of the individual\nSrRuO$_3$ layers rather than in the formation of skyrmions."
    },
    {
        "anchor": "From metallic glasses to nanocrystals: Molecular dynamics simulations on\n  the crossover from glass-like to grain-boundary-mediated deformation\n  behaviour: Nanocrystalline metals contain a large fraction of high-energy grain\nboundaries, which may be considered as glassy phases. Consequently, with\ndecreasing grain size, a crossover in the deformation behaviour of nanocrystals\nto that of metallic glasses has been proposed. Here, we study this crossover\nusing molecular dynamics simulations on bulk glasses, glass-crystal\nnanocomposites, and nanocrystals of Cu64Zr36 with varying crystalline volume\nfractions induced by long-time thermal annealing. We find that the grain\nboundary phase behaves like a metallic glass under constraint from the abutting\ncrystallites. The transition from glass-like to grain-boundary-mediated\nplasticity can be classified into three regimes: (1) For low crystalline volume\nfractions, the system resembles a glass-crystal composite and plastic flow is\nlocalised in the amorphous phase; (2) with increasing crystalline volume\nfraction, clusters of crystallites become jammed and the mechanical response\ndepends critically on the relaxation state of the glassy grain boundaries; (3)\nat grain sizes $\\geq$ 10 nm, the system is jammed completely, prohibiting pure\ngrain-boundary plasticity and instead leading to co-deformation. We observe an\ninverse Hall-Petch effect only in the second regime when the grain boundary is\nnot deeply relaxed. Experimental results with different grain boundary states\nare therefore not directly comparable in this regime.",
        "positive": "Anomalous critical point behavior in dilute magnetic semiconductor\n  (Ca,Na)(Zn,Mn)2Sb2: In this paper we report successful synthesis and magnetic properties of\n(Ca,Na)(Zn,Mn)2Sb2 as a new ferromagnetic dilute magnetic semiconductor (DMS).\nIn this DMS material the concentration of magnetic moments can be controlled\nindependently from the concentration of electric charge carriers that are\nrequired for mediating magnetic interactions between these moments. This\nfeature allows us to separately investigate the effect of carriers and of spins\non the ferromagnetic properties of this new DMS alloy, and particularly of the\ncritical ferromagnetic behavior. We use modified Arrott plot technique to\nestablish critical exponents b, g, and d of this alloy. We find that at low Mn\nconcentrations (< 10 at.%), it is governed by short-range 3D-Ising behavior,\nwith experimental values of b, g, and d very close to theoretical 3D-Ising\nvalues of 0.325, 1.24, and 4.815. However, as the Mn concentration increases,\nthis DMS material exhibits a mixed-phase behavior, with g retaining its\n3D-Ising characteristics, but b crossing over to longer-range mean-field\nbehavior."
    },
    {
        "anchor": "Phonon and Thermal Properties of Exfoliated Tantalum Diselenide Thin\n  Films: We report on the phonon and thermal properties of thin films of tantalum\ndiselenide (2H-TaSe2) obtained via the graphene-like mechanical exfoliation of\ncrystals grown by chemical vapor transport. The ratio of the intensities of the\nRaman peak from the Si substrate and the E2g peak of TaSe2 presents a\nconvenient metric for quantifying film thickness. The temperature coefficients\nfor two main Raman peaks, A1g and E2g, are -0.013 and -0.0097 cm-1/oC,\nrespectively. The Raman optothermal measurements indicate that the room\ntemperature thermal conductivity in these films decreases from its bulk value\nof ~16 W/mK to ~9 W/mK in 45-nm thick films. The measurement of electrical\nresistivity of the field-effect devices with TaSe2 channels indicates that heat\nconduction is dominated by acoustic phonons in these van der Waals films. The\nscaling of thermal conductivity with the film thickness suggests that the\nphonon scattering from the film boundaries is substantial despite the sharp\ninterfaces of the mechanically cleaved samples. These results are important for\nunderstanding the thermal properties of thin films exfoliated from TaSe2 and\nother metal dichalcogenides, as well as for evaluating self-heating effects in\ndevices made from such materials.",
        "positive": "First-principles analysis of the Al-rich corner of Al-Li-Cu phase\n  diagram: The phase diagram of Al-Li-Cu system in the Al-rich region was determined by\nmeans of first-principles calculations and statistical mechanics. The mixing\nenthalpies of many configurations for different lattices in the whole Al-Li-Cu\nsystem were determined by density functional theory simulations to find the\nstable phases in the convex hull. They were fitted with a cluster expansion to\ncalculate the free energy of the configurations with different compositions as\na function of temperature in the Al-rich region (Al content > 40 at. %) by\nmeans of Monte Carlo simulations. It was found that the ground state phases in\nthe Al-rich part of the Al-Li-Cu phase diagram were {\\alpha}-Al, {\\theta}'\n(Al2Cu), {\\delta}' (Al3Li), {\\delta} (AlLi) and T1 (Al6Cu4Li3), while\n{\\theta}'' (Al3Cu), T1' (Al2CuLi) and Al3Cu2Li were found on the lowest mixing\nenthalpy surfaces of their lattices and were metastable. {\\alpha}-Al, {\\delta}\nand T1 are stable phases in the whole temperature range while {\\delta}' becomes\nmetastable at very low temperature and {\\theta} (Al2Cu) replaces {\\theta}' as\nthe stable phase at approximately 550 K due to the vibrational entropic\ncontribution. In addition, the phase diagram in the Al-rich region was built\nand it was shown in isothermal sections from 100 K to 900 K. They were in good\nagreement with the limited experimental data in the literature and provided new\ninformation regarding the stability, solubility and stoichiometry of the\ndifferent phases. This information is important to understand the precipitation\nmechanisms during high temperature aging."
    },
    {
        "anchor": "Large Enhancement of Thermoelectric Efficiency Due to a Pressure-Induced\n  Lifshitz Transition in SnSe: Lifshitz transition, a change in Fermi surface topology, is likely to greatly\ninfluence exotic correlated phenomena in solids, such as high-temperature\nsuperconductivity and complex magnetism. However, since the observation of\nFermi surfaces is generally difficult in the strongly correlated systems, a\ndirect link between the Lifshitz transition and quantum phenomena has been\nelusive so far. Here, we report a marked impact of the pressure-induced\nLifshitz transition on thermoelectric performance for SnSe, a promising\nthermoelectric material without strong electron correlation. By applying\npressure up to 1.6 GPa, we have observed a large enhancement of thermoelectric\npower factor by more than 100% over a wide temperature range (10-300 K).\nFurthermore, the high carrier mobility enables the detection of quantum\noscillations of resistivity, revealing the emergence of new Fermi pockets at\n~0.86 GPa. The observed thermoelectric properties linked to the multi-valley\nband structure are quantitatively reproduced by first-principles calculations,\nproviding novel insight into designing the SnSe-related materials for potential\nvalleytronic as well as thermoelectric applications.",
        "positive": "Dopant Solubility, and Charge Compensation in La-doped SrSnO3 Films: We investigate lanthanum (La) as an n-type dopant in the strain-stabilized\ntetragonal phase of SrSnO3 grown on GdScO3 (110) using a radical-based hybrid\nmolecular beam epitaxy approach. Fully coherent, epitaxial films with\natomically smooth film surface were obtained irrespective of doping density. By\ncombining secondary ion mass spectroscopy and Hall measurements, we demonstrate\nthat each La atom contributes to one electron to the film confirming it\noccupies Sr-site in SrSnO3 and that it is completely activated. Carrier density\nexceeding 1 x 10^20 cm-3 was achieved in LSSO films, which is in excellent\nagreement with the dopant-solubility limit predicted by the density functional\ntheory calculations. A record-high room-temperature mobility of 70 cm2V-1s-1 at\n1 x 10^20 cm-3 was obtained in 12 nm La-doped SrSnO3 film making this the\nthinnest perovskite oxide semiconductor with a reasonably high electron\nmobility at room temperature. We discuss the structure-dopant-transport\nproperty relationships providing essential knowledge for the design of\nelectronic devices using these materials."
    },
    {
        "anchor": "Insights into the enhancement of oxygen mass transport properties of\n  strontium doped lanthanum manganite interface-dominated thin films: Strontium doped lanthanum manganite thin films were deposited by pulsed laser\ndeposition on yttria stabilized zirconia single crystals for a comprehensive\nelectrochemical characterization of the material acting as a cathode. A\nphysically meaningful electrical model was employed to fit the electrochemical\nimpedance spectroscopy results in order to extract the main oxygen mass\ntransport parameters as a function of the temperature and oxygen partial\npressure. The oxygen diffusion and surface exchange coefficients extracted from\nthe analysis showed several orders of magnitude of enhancement with respect to\nthe bulk values reported in the literature and an unexpectedly low dependence\nwith the oxygen partial pressure. Different observations were combined to\npropose a mechanism for the enhanced incorporation of oxygen in interface\ndominated thin films mainly based on the high concentration of oxygen vacancies\nexpected in the grain boundaries.",
        "positive": "Three-dimensional continuum dislocation theory: A three-dimensional continuum dislocation theory for single crystals\ncontaining curved dislocations is proposed. A set of governing equations and\nboundary conditions is derived for the true placement, plastic slips, and loop\nfunctions in equilibrium that minimize the free energy of crystal among all\nadmissible functions, provided the resistance to the dislocation motion is\nnegligible. For the non-vanishing resistance to dislocation motion the\ngoverning equations are derived from the variational equation that includes the\ndissipation function. A simplified theory for small strains is also provided.\nAn asymptotic solution is found for the two-dimensional problem of a single\ncrystal beam deforming in single slip and simple shear."
    },
    {
        "anchor": "Insights into the high-pressure behaviour of solid bromine from hybrid\n  DFT calculations: Understanding the properties of molecular solids at high pressure is a key\nelement in the development of new solid-state theories. However, the most\ncommonly used generalized-gradient approximation (GGA) of the density\nfunctional theory (DFT) often fails to correctly describe the behavior of these\nsystems at high pressure. Here we utilize the hybrid DFT approach to model the\nproperties of elemental bromine at high pressure. The calculations reproduce in\nvery good agreement with experiment the properties of the molecular phase I\n(Cmca symmetry) and its pressure-induced transition into the non-molecular\nphase II (Immm). The experimentally yet unobserved transition into phase III\n(I4/mmm) is predicted to occur at 128 GPa, followed by subsequent formation of\nan fcc lattice at 188 GPa. Analysis of the structure and electronic properties\nof the modelled phases indicates that the molecular Cmca phase becomes metallic\njust at the borderline of its stability, and that both Immm and I4/mmm phases\nare metallic and quasi-2D. Finally, we show that the incommensurate phases of\nbromine postulated from experiment are transient species which can be viewed as\nintermediates in the dissociation process occurring at the boundary of the\ntransition from phase I to phase II.",
        "positive": "Interatomic exchange coupling of BCC iron: We performed first-principle calculations on the exchange interaction (EI)\nbetween atoms in BCC-Fe strained volumetrically. Our results show that the\nvolume-dependence of the EI deviates considerably from the Bethe-Slater curve.\nThis behavior is discussed in terms of the on-site and/or inter-site direct\nexchange interactions between electrons."
    },
    {
        "anchor": "Deterministic Localization of Strain-induced Single-photon Emitters in\n  Multilayer GaSe: Nanoscale strain has emerged as a powerful tool for controlling single-photon\nemitters (SPEs) in atomically thin transition metal dichalcogenides (TMDCs)(1,\n2). However, quantum emitters in monolayer TMDCs are typically unstable in\nambient conditions. Multilayer two-dimensional (2D) TMDCs could be a solution,\nbut they suffer from low quantum efficiency, resulting in low brightness of the\nSPEs. Here, we report the deterministic spatial localization of strain-induced\nsingle-photon emitters in multilayer GaSe by nanopillar arrays. The\nstrain-controlled quantum confinement effect introduces well-isolated\nsub-bandgap photoluminescence and corresponding suppression of the broad band\nedge photoluminescence. Clear photon-antibunching behavior is observed from the\nquantum dot-like GaSe sub-bandgap exciton emission at 3.5 Kelvin. The\nstrain-dependent confinement potential and the brightness are found to be\nstrongly correlated, suggesting a promising route for tuning and controlling\nSPEs. The comprehensive investigations of strain-engineered GaSe SPEs provide a\nsolid foundation for the development of 2D devices for quantum photonic\ntechnologies.",
        "positive": "Population inversion and ultrafast terahertz nonlinearity of transient\n  Dirac fermions in Cd$_3$As$_2$: Harmonic generation provides an efficient tool for the study of ultrafast\nnonlinear dynamics. We report on time-resolved optical-pump\nterahertz-harmonic-generation spectroscopic investigation of ultrafast\nnonlinearity in a prototypical three-dimensional Dirac semimetal Cd$_3$As$_2$.\nA transient population inversion characterized by excessive nonthermal Dirac\nelectrons and holes is found to be very sensitive and responsive to a periodic\nterahertz drive, leading to very efficient terahertz third-harmonic generation.\nBased on the Boltzmann transport theory, we analyze the terahertz field-driven\nkinetics of the transient Dirac fermions that is responsible for the observed\nstrong terahertz nonlinearity."
    },
    {
        "anchor": "The superheated Melting of Grain Boundary: Based on a model of the melting of Grain Boundary (GB), we discuss the\npossibility of the existence of superheated GB state. A Molecular Dynamics\nsimulation presented here shows that the superheated GB state can realized in\nthe high symmetric tilt GB. Whether the sizes of liquid nuclei exceed a\ncritical size determined the superheating grain boundary melting or not. Our\nresults also indicate that the increase of melting point due to pressure is\nsmaller than the superheating due to nucleation mechanism.",
        "positive": "Database-driven High-Throughput Calculations and Machine Learning Models\n  for Materials Design: This paper reviews past and ongoing efforts in using high-throughput ab-inito\ncalculations in combination with machine learning models for materials design.\nThe primary focus is on bulk materials, i.e., materials with fixed, ordered,\ncrystal structures, although the methods naturally extend into more complicated\nconfigurations. Efficient and robust computational methods, computational\npower, and reliable methods for automated database-driven high-throughput\ncomputation are combined to produce high-quality data sets. This data can be\nused to train machine learning models for predicting the stability of bulk\nmaterials and their properties. The underlying computational methods and the\ntools for automated calculations are discussed in some detail. Various machine\nlearning models and, in particular, descriptors for general use in materials\ndesign are also covered."
    },
    {
        "anchor": "Acoustic Deformation Potentials of $n$-Type PbTe from First Principles: We calculate the uniaxial and dilatation acoustic deformation potentials,\n$\\Xi^{\\text{L}}_{u}$ and $\\Xi^{\\text{L}}_{d}$, of the conduction band L valleys\nof PbTe from first principles, using the local density approximation (LDA) and\nhybrid functional (HSE03) exchange-correlation functionals. We find that the\nchoice of a functional does not substantially affect the effective band masses\nand deformation potentials as long as a physically correct representation of\nthe conduction band states near the band gap has been obtained. Fitting of the\nelectron-phonon matrix elements obtained in density functional perturbation\ntheory (DFPT) with the LDA excluding spin orbit interaction (SOI) gives\n$\\Xi^{\\text{L}}_u = 7.0$~eV and $\\Xi^{\\text{L}}_d = 0.4$~eV. Computing the\nrelative shifts of the L valleys induced by strain with the HSE03 functional\nincluding SOI gives $\\Xi^{\\text{L}}_u = 5.5$~eV and $\\Xi^{\\text{L}}_d =\n0.8$~eV, in good agreement with the DFPT values. Our calculated values of\n$\\Xi^{\\text{L}}_u$ agree fairly well with experiment ($\\sim 3-4.5$~eV). The\ncomputed values of $\\Xi^{\\text{L}}_d$ are substantially smaller than those\nobtained by fitting electronic transport measurements ($\\sim 17-22$~eV),\nindicating that intravalley acoustic phonon scattering in PbTe is much weaker\nthan previously thought.",
        "positive": "Data mining and accelerated electronic structure theory as a tool in the\n  search for new functional materials: Data mining is a recognized predictive tool in a variety of areas ranging\nfrom bioinformatics and drug design to crystal structure prediction. In the\npresent study, an electronic structure implementation has been combined with\nstructural data from the Inorganic Crystal Structure Database to generate\nresults for highly accelerated electronic structure calculations of about\n22,000 inorganic compounds. It is shown how data mining algorithms employed on\nthe database can identify new functional materials with desired materials\nproperties, resulting in a prediction of 136 novel materials with potential for\nuse as detector materials for ionizing radiation. The methodology behind the\nautomatized ab-initio approach is presented, results are tabulated and a\nversion of the complete database is made available at the internet web site\nhttp://gurka.fysik.uu.se/ESP/ (Ref.1)."
    },
    {
        "anchor": "Imparity in valley population for single layer transition metal\n  dichalcogenides under elliptical polarization: The illumination of a single-layer transition metal dichalcogenide with an\nelliptically-polarized light beam is shown to give rise to a differential rate\nof inter-band carrier excitation between the valence and conduction states\naround the valley edges, $ K $ and $ K^{'} $. This rate with a linear\ndependence on the beam ellipticity and inverse of the optical gap manifests as\nan asymmetric Fermi distribution between the valleys or a non-equilibrium\npopulation which under an external field and a Berry curvature induced\nanomalous velocity results in an externally tunable finite valley Hall current.\nSurface imperfections that influence the excitation rates are included through\nthe self-consistent Born approximation. Additionally, we show that circular\ndichroism in the vicinity of the valley edges also exhibits an ellipticity\ndependence.",
        "positive": "A general figure of merit for thick and thin transparent conductive\n  carbon nanotube coatings: We suggest a wavelength-dependent figure of merit for transparent conducting\nnanotube networks, composed of the sheet resistance and the optical density. We\nargue that this would be more useful than other suggestions prevailing in the\nliterature, because it relies on more realistic assumptions regarding the\noptical parameters of real nanotubes: it takes into account the fact that the\ndc resistivity depends on the concentration of free carriers, while the visible\nabsorption is caused by bound carriers. Based on sheet resistance measurements\nand wide-range transmission spectra, we compare several commercial nanotube\ntypes and find correlation between metal enrichment and figure of merit. A\nsimple graphical approach is suggested to determine if the required optical and\ntransport properties can be achieved by varying the thickness of the nanotube\nlayer or a more aggressive treatment is needed. The procedure can be extended\nto oxide coatings as well."
    },
    {
        "anchor": "Density functionals with asymptotic-potential corrections are required\n  for the simulation of spectroscopic properties of materials: Five effects of correction of the asymptotic potential error in density\nfunctionals are identified that significantly improve calculated properties of\nmolecular excited states involving charge-transfer character. Newly developed\nmaterials-science computational methods are used to demonstrate how these\neffects manifest in materials spectroscopy. Connection is made considering\nchlorophyll-a as a paradigm for molecular spectroscopy, 22 iconic materials as\nparadigms for 3D materials spectroscopy, and the VN- defect in hexagonal boron\nnitride as an example of the spectroscopy of defects in 2D materials pertaining\nto nanophotonics. Defects can equally be thought of as being \"molecular\" and\n\"materials\" in nature and hence bridge the realms of molecular and materials\nspectroscopies. It is concluded that the density functional HSE06, currently\nconsidered as the standard for accurate calculations of materials spectroscopy,\nshould be replaced, in most instances, by the computationally similar but\nasymptotically corrected CAM-B3LYP functional, with some specific functionals\nfor materials use only providing further improvements.",
        "positive": "First-principles theory of the orbital magnetization: We compute the orbital magnetization in real materials by evaluating a\nrecently discovered formula for periodic systems, within density functional\ntheory. We obtain improved values of the orbital magnetization in the\nferromagnetic metals Fe, Co, and Ni, by taking into account the contribution of\nthe interstitial regions neglected so far in literature. We also use the\norbital magnetization to compute the EPR $g$-tensor in molecules and solids.\nThe present approach reproduces the $g$-tensor obtained by linear response\n(LR), when the spin-orbit can be treated as a perturbation. However, it can\nalso be applied to radicals and defects with an orbital-degenerate ground-state\nor containing heavy atoms, that can not be properly described by LR."
    },
    {
        "anchor": "Some thoughts on dynamic effective properties -- a working document: The main purpose of this work is to address the question of the utility of\n\"effective constitutive relations\" for problems in dynamics. This is done in\nthe context of longitudinal shear waves in an elastic medium that is\nperiodically laminated, with attention restricted to plane waves propagating in\nthe direction normal to the interfaces. The properties of such waves can be\nfound by employing Floquet theory, implemented via a \"transfer matrix\"\nformulation. Problems occur at frequencies beyond those that define the first\npass band, associated in part with the difficulty of assigning a unique\nwavenumber to the wave. This problem is examined, paying careful attention to\nthe requirements of causality and passivity. The transmission of waves into a\nhalf-space is discussed by studying the impedance of the half-space, both\ndirectly and in the \"effective medium\" approximation, and an alternative way of\nlooking at this problem, based on construction of the Green's function, is\ndeveloped.",
        "positive": "Inverse response behaviour in the bright ring radius measurement of the\n  Czochralski process I: Investigation: This is the first part of a two-article series that deals with the\ninvestigation of the anomalous behaviour in the radius measurement signal of\nthe Czochralski (Cz) process and its mitigation in a feedback control system.\nThe inverse or anomalous behaviour is indeed a measurement signal response,\nwhich initially is opposite to that of the expected response. This is a crucial\nand limiting factor in feedback control system design. The paper presents the\ndevelopment of a rigorous 3D ray-tracing method to investigate the inverse\nresponse behaviour in the measurement signal. The results of this study provide\nan insight into the dynamic behaviour of the Cz growth process. It can serve as\na guideline for achieving effective crystal radius control, which is addressed\nin the second part of this article series."
    },
    {
        "anchor": "Improved Thin Film Quality and Photoluminescence of N-Doped Epitaxial\n  Germanium-on-Silicon using MOCVD: Ge-on-Si structures in-situ doped with phosphorus or arsenic via metal\norganic chemical vapor deposition (MOCVD) were investigated. Surface roughness,\nstrain, threading dislocation desnity, Si-Ge interdiffusion, dopant diffusion,\nand photoluminescence were characterized to study the impacts of defect\nannealing and Si substrate offcut effects on the Ge film quality and most\nimportantly, the light emission properties. All samples have a smooth surface\n(roughness < 1.5 nm), and the Ge films have a small tensile strain of 0.2%.\nAs-grown P and As-doped Ge films have threading dislocaiton densities from\n2.8e8 to 1.1e9 cm^(-2) without defect annealing. With thermal cycling, these\nvalues reduced to 1-1.5e8 cm^(-2). The six degree offcut of the Si substrate\nwas shown to have little impact. In contrast to delta doping, the out-diffusion\nof dopants has been successfully suppressed to retain the doping concentration\nupon defect annealing. However, the photoluminescence intensity decreases\nmostly due to Si-Ge interdiffusion, which also causes a blue-shift in the\nemission wavelength. Compared to a benckmarking sample from the first Ge laser\nwork doped by delta doping method in 2012, the as-grown P or As-doped Ge films\nhave similar photoluminescence intensity at a 25% doping concentration and\nsmoother surface, which are promising for Ge lasers with better light emission\nefficiencies.",
        "positive": "Magnetoresistance, noise properties and the Koshino-Taylor effect in the\n  quasi-1D oxide KRu_4O_8: The low temperature electronic and galvanomagnetic transport properties of\nthe low dimensional oxide KRu_4O_8 are experimentally considered. A quadratic\ntemperature variation of the resistivity is observed to be proportional to the\nresidual resistivity. It shows the role of inelastic electron scattering\nagainst impurities, i.e. a large Koshino-Taylor effect, rather than a\nconsequence of strong electronic correlations. In the same temperature range,\nthe Kohler rule is not fulfilled. The resistance noise increases also sharply,\npossibly due to a strong coupling of carriers with lattice fluctuations in this\nlow dimensional compound."
    },
    {
        "anchor": "Electronic and dynamical properties of cobalt monogermanide CoGe phases\n  under pressure: We present the pressure dependence of the electronic and dynamical properties\nof six different CoGe phases: orthorhombic Cmmm, hexagonal P6/mmm and\nP$\\bar{6}$2m, monoclinic C2/m, cubic P2$_{1}$3, and orthorhombic Pnma. Using\nfirst-principles DFT calculations and the direct force-constants method, we\nstudy the dynamical stability of individual phases under external pressure. We\nshow that the orthorombic Cmmm and hexagonal P6/mmm structures are unstable\nover a broad pressure range and most pronounced imaginary phonon soft mode in\nboth cases leads to a stable hexagonal P$\\bar{6}$2m structure of the lowest\nground-state energy of all studied phases at ambient and low (below $\\sim 3$\nGPa) external pressure. Under these conditions, the cubic P2$_{1}$3 phase has\nthe highest energy, however, together with monoclinic C2/m and orthorombic Pnma\nit is dynamically stable and all these three structures can potentially coexist\nas meta-stable phases. Above $\\sim 3$ GPa, the cubic P2$_{1}$3 phase becomes\nthe most energetically favorable. Fitting the Birch--Murnaghan equation of\nstate we derive bulk modulus for all mentioned phases, which indicate\nrelatively high resistance of CoGe to compression. Such conclusions are\nconfirmed by band structure calculations. Additionally, we show that electronic\nbands of the hexagonal P$\\bar{6}$2m phase reveal characteristic features of the\nkagome-like structure, while in the cubic P2$_{1}$3 phase spectrum, one can\nlocate spin-1 and double Weyl fermions. In both cases, the external pressure\ninduces the Lifshitz transition, related to the modification of the Fermi\nsurface topology.",
        "positive": "Thermoelectric Signal Enhancement by Reconciling the Spin Seebeck and\n  Anomalous Nernst Effects in Ferromagnet/Non-magnet Multilayers: The utilization of ferromagnetic (FM) materials in thermoelectric devices\nallows one to have a simpler structure and/or independent control of electric\nand thermal conductivities, which may further remove obstacles for this\ntechnology to be realized. The thermoelectricity in FM/non-magnet (NM)\nheterostructures using an optical heating source is studied as a function of NM\nmaterials and a number of multilayers. It is observed that the overall\nthermoelectric signal in those structures which is contributed by spin Seebeck\neffect and anomalous Nernst effect (ANE) is enhanced by a proper selection of\nNM materials with a spin Hall angle that matches to the sign of the ANE.\nMoreover, by an increase of the number of multilayer, the thermoelectric\nvoltage is enlarged further and the device resistance is reduced,\nsimultaneously. The experimental observation of the improvement of\nthermoelectric properties may pave the way for the realization of magnetic-(or\nspin-) based thermoelectric devices."
    },
    {
        "anchor": "Octonacci Photonic Crystals with Negative Refraction Index Materials: We investigate the optical transmission spectra for $s$-polarized (TE) and\n$p$-polarized (TM) waves in one-dimensional photonic quasicrystals on a\nquasiperiodic multilayer structure made up by alternate layers of SiO$_{2}$ and\n\\textit{metamaterials}, organized by following the Octonacci sequence.\nMaxwell's equations and the transfer-matrix technique are used to derive the\ntransmission spectra for the propagation of normaly and obliquely incident\noptical fields. We assume Drude-Lorentz-type dispersive response for the\ndielectric permittivity and magnetic permeability of the metamaterials. For\nnormally incident waves, we observe that the spectra does not have self-similar\nbehavior or mirror symmetry and it also features the absence of optical band\ngap. Also for normally incident waves, we show regions of full transmittance\nwhen the incident angle $\\theta_{C} = 0^{\\circ}$ in a particular frequency\nrange.",
        "positive": "Transition metal ions in ZnO: effects of intrashell Coulomb repulsion on\n  electronic properties: Electronic structure of the transition metal (TM) dopants in ZnO is\ncalculated by first principles approach. Analysis of the results is focused on\nthe properties determined by the intrashell Coulomb coupling. The role of both\ndirect and exchange interaction channel is analyzed. The coupling is manifested\nin the strong charge state dependence of the TM gap levels, which leads to the\nmetastability of photoexcited Mn, and determines the accessible equilibrium\ncharge states of TM ions. The varying magnitude of the exchange coupling is\nreflected in the dependence of the spin splitting energy on the chemical\nidentity across the 3$d$ series, as well as the charge state dependence of\nspin-up spin-down exchange splitting."
    },
    {
        "anchor": "Light-induced giant and persistent changes in the converse\n  magnetoelastic effects in Ni/BaTiO3 multiferroic heterostructure: Magnetoelastic and magnetoelectric coupling in the artificial multiferroic\nheterostructures facilitate valuable features for device applications such as\nmagnetic field sensors and electric write magnetic-read memory devices. In a\nferromagnetic/ferroelectric heterostructures, the strain mediated coupling\nexploits piezoelectricity/electrostriction in ferroelectric phase and\nmagnetostriction/piezomagnetism in ferromagnetic phase. Such verity of these\ncombined effect can be manipulated by an external perturbation, such as\nelectric field, temperature or magnetic field. Here, we demonstrate the\nremote-controlled tunability of these effects under the visible, coherent and\npolarized light. The combined surface and bulk magnetic study of\ndomain-correlated Ni/BaTiO3 heterostructure reveals that the system is strong\nsensitive about the light illumination via the combined effect of converse\npiezoelectric, magnetoelastic coupling and converse magnetostriction.\nWell-defined ferroelastic domain structure is fully transferred from a\ntetragonal ferroelectric to magnetostrictive layer via interface strain\ntransfer during the film growth. The visible light illumination is used to\nmanipulate the original ferromagnetic microstructure by the light-induced\ndomain wall motion in ferroelectric, consequently the domain wall motion in the\nferromagnetic layer. Our findings mimic the attractive remote-controlled\nferroelectric random-access memory write and magnetic random-access memory read\napplication scenarios, hence, can be proven as a novel perspective for room\ntemperature device applications.",
        "positive": "Hybrid nodal surface and nodal line phonons in solids: Phonons have provided an ideal platform for a variety of intriguing physical\nstates, such as non-Abelian braiding and the Haldane model. It is promising\nthat phonons will realize the complicated nodal states accompanying unusual\nquantum phenomena. Here, we propose the hybrid nodal surface and nodal line\n(NS+NL) phonons beyond the single-genre nodal phonons. We categorize the NS+NL\nphonons into two- and four-band situations based on symmetry analysis and\ncompatibility relationships. Combining database screening with first-principles\ncalculations, we identify the ideal candidate materials for realizing all\ncategorized NS+NL phonons. Our calculations and tight-binding models further\ndemonstrate that the interplay between NS and NL induces unique phenomena. In\nspace group (SG) 113, the quadratic NL acts as a hub of the Berry curvature\nbetween two NSs, generating ribbonlike surface states (SSs). In SG 128, the NS\nserves as the counterpart of the Weyl NL, in which NS-NL mixed topological SSs\nare observed. Our findings extend the scope of hybrid nodal states and enrich\nthe phononic states in realistic materials."
    },
    {
        "anchor": "B2O3 glass former as a molecular matter revealed by heat capacity: Heat capacity of B2O3 glass former in a wide temperature region is described\nwell with the intrinsic motions for non-spherical B2O3 molecules, revealing\nthat rather than a conventional network glass former, B2O3 is a typical\nmolecular matter in which the transition from liquid to glass in the system\ncorresponds to the frozen of translational motions for molecules. The finding\nmight provide an opportunity to understand the mysterious glass transition, as\nwell as the intrinsic difference between solids and liquids.",
        "positive": "Study of phonons in irradiated epitaxial thin films of UO$_2$: We report experiments to determine the effect of radiation damage on the\nphonon spectra of the most common nuclear fuel, UO$_2$. We have irradiated thin\n($\\sim$ 300 nm) epitaxial films of UO$_2$ with 2.1 MeV He$^{2+}$ ions to 0.15\ndpa and a lattice swelling of $\\Delta$a/a $\\sim$ 0.6 %, and then used\ngrazing-incidence inelastic X-ray scattering to measure the phonon spectrum. We\nsucceeded to observe the acoustic modes, both transverse and longitudinal,\nacross the Brillouin zone. The phonon energies, in both the pristine and\nirradiated samples, are unchanged from those observed in bulk material. On the\nother hand, the phonon linewidths (inversely proportional to the phonon\nlifetimes), show a significant broadening when comparing the pristine and\nirradiated samples. This effect is shown to increase with phonon energy across\nthe Brillouin zone. The decreases in the phonon lifetimes of the acoustic modes\nare roughly consistent with a 50 % reduction in the thermal conductivity."
    },
    {
        "anchor": "Inverse design of two-dimensional materials with invertible neural\n  networks: The ability to readily design novel materials with chosen functional\nproperties on-demand represents a next frontier in materials discovery.\nHowever, thoroughly and efficiently sampling the entire design space in a\ncomputationally tractable manner remains a highly challenging task. To tackle\nthis problem, we propose an inverse design framework (MatDesINNe) utilizing\ninvertible neural networks which can map both forward and reverse processes\nbetween the design space and target property. This approach can be used to\ngenerate materials candidates for a designated property, thereby satisfying the\nhighly sought-after goal of inverse design. We then apply this framework to the\ntask of band gap engineering in two-dimensional materials, starting with MoS2.\nWithin the design space encompassing six degrees of freedom in applied tensile,\ncompressive and shear strain plus an external electric field, we show the\nframework can generate novel, high fidelity, and diverse candidates with\nnear-chemical accuracy. We extend this generative capability further to provide\ninsights regarding metal-insulator transition, important for memristive\nneuromorphic applications among others, in MoS2 which is not otherwise possible\nwith brute force screening. This approach is general and can be directly\nextended to other materials and their corresponding design spaces and target\nproperties.",
        "positive": "Can Ordered Precursors Promote the Nucleation of Solid Solutions?: Crystallization often proceeds through successive stages that lead to a\ngradual increase in organization. Using molecular simulation, we determine the\nnucleation pathway for solid solutions of copper and gold. We identify a new\nnucleation mechanism (liquid$\\to$$L1_2$~precursor$\\to$solid solution),\ninvolving a chemically ordered intermediate that is more organized than the end\nproduct. This nucleation pathway arises from the low formation energy of $L1_2$\nclusters which, in turn, promote crystal nucleation. We also show that this\nmechanism is composition-dependent since the high formation energy of other\nordered phases precludes them from acting as precursors."
    },
    {
        "anchor": "Manifestation of T-Exciton Migration in the Kinetics of Singlet Fission\n  in Organic Semiconductors: Kinetics of singlet fission in organic semiconductors, in which the excited\nsinglet state (S_1) spontaneously splits into a pair of triplet (T) excitons,\nis known to be strongly influenced by back geminate annihilation of TT-pairs.\nWe show that this influence can be properly described only by taking into\naccount the diffusive exciton migration. The migration effect is treated in the\nmodel of two kinetically coupled states: the intermediate state of interacting\nTT-pairs and the state of migrating excitons. Within this model the singlet\nfission (including magnetic field effects) is studied as applied to the\nfluorescence decay kinetics (FDK) I_{S_1}(t) for S_1-state. The analysis shows\nthat migration strongly affects the FDK resulting, in particular, in the\nuniversal long-time dependence I_{S_1}(t) \\sim t^{-3/2}. The model accurately\ndescribes the FDK, recently observed for a number of systems. Possible\napplications of the considered model to the analysis of mechanisms of\nmigration, using experimentally measured FDK, are briefly discussed.",
        "positive": "Comment on \"Scaling of the anomalous Hall effect in Sr(1-x)Ca(x)RuO3\": We argue that the scaling of the anomalous Hall effect (AHE) by Mathieu et\nal. [Phys. Rev. Lett. 93, 016602 (2004)] does not provide support to the\ninterpretation of the AHE in SrRuO3 as an intrinsic effect due to Berry phase\nmonopoles in k-space."
    },
    {
        "anchor": "Raman spectroscopy study of internal dynamics in\n  Pb(Zn_{1/3}Nb_{2/3})O_{3} and 95.55%Pb(Zn_{1/3}Nb_{2/3})O_{3}-4.5%PbTiO_{3}\n  crystals: Pb(Zn$_{1/3}$Nb$_{2/3}$)O$_{3}$ is one of the simplest representatives of the\nlead ferroelectric relaxors. Its solid solution with PbTiO$_{3}$, at\nconcentrations near the morphotropic phase boundary, is especially important.\nIn this paper, we apply the tested earlier on Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_{3}$\napproach, to analyze the light scattering from both, nominally pure\nPb(Zn$_{1/3}$Nb$_{2/3} $)O$_{3}$ crystal and a crystal containing 4.5% of\nPbTiO$_{3}$, measured in a broad temperature range from 1000 to 100 K. We\npropose a comprehensive picture of the temperature evolution of the lattice\ndynamics in these crystals and associated structural transformations. We show,\nthat in PZN, like in PMN, short-lived dynamic lattice distortions exist even at\nthe highest measured temperatures. With cooling down, these distortions develop\nin Fm$\\bar{3}$m clusters and R3m polar nanoregions that are still capable of\nreorientational motion. From the Burns temperature T$_{d}$, this motion becomes\nprogressively restricted. The freezing process starts at the temperature\nT$^{*}$ and continues down to T$_{d0}$. The major Raman lines in all these\nmaterials behave very similarly. However, the temperature behavior of a weak\nline E in each case is essentially different. Its splitting can serve as a\nmeasure of the order parameter of the system.",
        "positive": "Tuning sizes, morphologies, and magnetic properties of mono- vs.\n  multi-core iron oxide nanoparticles through control of added water in the\n  polyol synthesis: The polyol route is a versatile and up-scalable method to produce large\nbatches of iron oxide nanoparticles with well-defined structure and magnetic\nproperties. Controlling parameters such as temperature and duration of\nreaction, heating profile, nature of polyol solvent or of organometallic\nprecursors were reported in previous studies of literature, but none of them\ndescribed yet the crucial role of water in the forced hydrolysis pathway, whose\npresence is mandatory for nanoparticle production. This communication\ninvestigates the influence of the water amount and temperature at which it is\ninjected in the reflux system for either pure polyol or mixture with a\npoly(hydroxy) amine. Distinct morphologies of nanoparticles were thereby\nobtained, from ultra-ultra-small smooth spheres down to 4 nm in diameter to\nlarge ones up to 37 nm in diameter. Nanoflowers were also synthesized, which\nare well-defined multi-core assemblies with narrow grain size dispersity. A\ndiverse and large library of samples was obtained by playing on the nature of\nsolvents and amount of water traces while keeping all the other parameters\nfixed. The varied morphologies lead to magnetic nanoparticles well-fitting to\nrequired applications among magnetic hyperthermia and MRI contrast agent, or\nboth."
    },
    {
        "anchor": "A short circuit in the electrical cables with polymer insulation: a new\n  look at the cause of its occurrence and non-traditional ways of solving the\n  problem: It is known that most of the electrical cables use as insulation compositions\nbased on polyvinyl chloride. Like most polymers, the latter is quite sensitive\nto thermal aging, which is not without reason, to be one of the main causes of\nthe various types of faults in the polymeric insulation, leading eventually to\na short circuit and fire. On the example of the most common polymer\ninsulator-PVC subjected to preliminary partial thermolysis, simulating the\nprocess of accelerated aging, we for the first time show that in this case as a\nresult of the aging process, the electrical conductivity of PVC can acquire\nabnormal (not obeying Ohm's law) character. In this case, transitions from a\nstate with normal (low) conductivity of PVC into the state with an ab-normally\nhigh conductivity was clearly observed, being spontaneous uncontrollable\nprocess. Es-pecially the large-scale nature of these changes allowing easily\ntransferring polyvinylchloride from a state of typical dielectric (insulator)\nin a class of conductors attracts attention.). Thus, an-other one of the most\nimportant features of a short circuit in the PVC insulation is opened. It is\nnoted that the reduction of fire hazards in this case (by the maximum possible\nelimination of the phenomenon of short circuit due to thermal aging of\npolymeric insulation) should be preventive in nature, as the most effective,\nsimple and convenient way.",
        "positive": "Coexistience of phononic six-fold, four-fold and three-fold excitations\n  in ternary antimonide Zr3Ni3Sb4: Three-, four-, and six-fold excitations have significantly extended the\nsubjects of condensed matter physics. There is an urgent need for a realistic\nmaterial that can have coexisting 3-, 4-, and 6-fold excitations. However,\nthese materials are uncommon because these excitations in electronic systems\nare usually broken by spin-orbit coupling (SOC) and normally far from the Fermi\nlevel. Unlike the case in electronic systems, the phonon systems with\nnegligible SOC effect, not constrained by the Pauli exclusion principle,\nprovide a feasible platform to realize these excitations in a wide frequency\nrange. Hence, in this work, we demonstrate by first-principle calculations and\nsymmetry analysis that perfect 3-, 4-, 6-fold excitations appear in the phonon\ndispersion rather than the band structures of Zr3Ni3Sb4, which is a well-known\nindirect-gap semiconductor with an Y3Au3Sb4-type structure. This material\nfeatures 3-fold quadratic contact triple-point phonon, 4-fold Dirac point\nphonon, and 6-fold point phonon. Moreover, these nodal-point phonons are very\nrobust to uniform strain. Two obvious phonon surface arcs of the [001] plane\nare extended in the whole Brillouin zone, which will facilitate their detection\nin future experimental studies. The current work provides an ideal model to\ninvestigate the rich excitations in a single material."
    },
    {
        "anchor": "Formation energies of charged defects in two-dimensional materials --\n  resolution of long-standing difficulties: Formation energies of charged point defects in semiconductors are calculated\nusing periodic supercells, which entail a divergence arising from long-range\nCoulombic interactions. The divergence is typically removed by the so-called\njellium approach. Recently, Wu, Zhang and Pantelides [WZP, Phys. Rev. Lett.\n119, 105501 (2017)] traced the origin of the divergence to the assumption that\ncharged defects are formed by physically removing electrons from or adding\nelectrons to the crystal, violating charge neutrality, a key principle of\nstatistical mechanics that determines the Fermi level. An alternative theory\nwas constructed by recognizing that \"charged\" defects form by trading carriers\nwith the energy bands, whereby supercells are always charge-neutral so that no\ndivergence is present and no ad-hoc procedures need to be adopted for\ncalculations. Here we give a more detailed exposition of the foundations of\nboth methods and show that the jellium approach can be derived from the\nstatistical-mechanics-backed WZP definition by steps whose validity cannot be\nassessed a priori. In particular, the divergence appears when the charge\ndensity of band carriers is dropped, leaving a supercharged crystal. In the\ncase of charged defects in two-dimensional (2D) materials, unphysical fields\nappear in vacuum regions. None of these pathological features are present in\nthe reformulated theory. Finally, we report new calculations in both bulk and\n2D materials. The WZP approach yields formation energies that differ from\njellium values by up to ~1 eV. By analyzing the spatial distribution of wave\nfunctions and defect potentials, we provide insights into the inner workings of\nboth methods and demonstrate that the failure of the jellium approach to\ninclude the neutralizing electron density of band carriers, as is the case in\nthe physical system, is responsible for the numerical differences between the\ntwo methods.",
        "positive": "Morphology-driven electrical and optical properties in graded\n  hierarchical transparent conducting Al:ZnO: Graded Al-doped ZnO layers, constituted by a mesoporous forest like system\nevolving into a compact transparent conductor, were synthesized by Pulsed Laser\nDeposition with different morphology to study the correlation with functional\nproperties. Morphology was monitored by measuring the resulting surface\nroughness and its effects on electrical conductivity (especially carrier\nmobility, which significantly decreases with increasing roughness) allow to\ndiscuss the limitations in conduction mechanisms. Significant changes in light\nscattering capability due to variations in morphology are also investigated and\ndiscussed to study the correlation between morphology and functional\nproperties."
    },
    {
        "anchor": "The role of the alloy structure in the magnetic behavior of granular\n  systems: The effect of grain size, easy magnetization axis and anisotropy constant\ndistributions in the irreversible magnetic behavior of granular alloys is\nconsidered. A simulated granular alloy is used to provide a realistic grain\nstructure for the Monte Carlo simulation of the ZFC-FC curves. The effect of\nannealing and external field is also studied. The simulation curves are in good\nagreement with the FC and ZFC magnetization curves measured on melt spun Cu-Co\nribbons.",
        "positive": "Morphology of buried interfaces in ion-assisted magnetron sputter\n  deposited 11B4C-containing Ni/Ti multilayer neutron optics investigated by\n  grazing incidence small angle scattering: Multilayer neutron optics require precise control of interface morphology for\noptimal performance. In this work, we investigate the effects of different\ngrowth conditions on the interface morphology of Ni/Ti based multilayers, with\na focus on incorporating low-neutron-absorbing 11B4C and using different ion\nassistance schemes. Grazing incidence small angle X-ray scattering was used to\nprobe the structural and morphological details of buried interfaces, revealing\nthat the layers become more strongly correlated and the interfaces form mounds\nwith increasing amounts of 11B4C. Applying high flux ion assistance during\ngrowth can reduce mound formation but lead to interface mixing, while a high\nflux modulated ion assistance scheme with an initial buffer layer grown at low\nion energy and the top layer at higher ion energy prevents intermixing. The\noptimal condition was found to be adding 26.0 at.% 11B4C combined with high\nflux modulated ion assistance. A multilayer with a period of 48.2 {\\AA} and 100\nperiods was grown under these conditions, and coupled fitting to neutron and\nX-ray reflectivity data revealed an average interface width of only 2.7 {\\AA},\na significant improvement over the current state-of-the-art commercial Ni/Ti\nmultilayers. Overall, our study demonstrates that the addition of 11B4C and the\nuse of high flux modulated ion assistance during growth can significantly\nimprove the interface morphology of Ni/Ti multilayers, leading to improved\nneutron optics performance."
    },
    {
        "anchor": "Nanocrystallization and Amorphization Induced by Reactive Nitrogen\n  Sputtering in Iron and Permalloy: Thin films of iron and permalloy Ni80Fe20 were prepared using an Ar+N2\nmixture with magnetron sputtering technique at ambient temperature. The\nnitrogen partial pressure, during sputtering process was varied in the range of\n0 to 100%, keeping the total gas flow at constant. At lower nitrogen pressures\nRN2<33% both Fe and NiFe, first form a nanocrystalline structure and an\nincrease in nitrogen partail pressure results in formation of an amorphous\nstructure. At intermediate nitrogen partial pressures, nitrides of Fe and NiFe\nwere obtained while at even higher nitrogen partial pressures, nitrides\nthemselves became nanocrystalline or amorphous. The surface, structural and\nmagnetic properties of the deposited films were studied using x-ray reflection\nand diffraction, transmission electron microscopy, polarized neutron\nreflectivity and using a DC extraction magnetometer. The growth behavior for\namorphous film was found different as compared with poly or nanocrystalline\nfilms. The soft-magnetic properties of FeN were improved on nanocrystallization\nwhile those of NiFeN were degraded. A mechanism inducing nanocrystallization\nand amorphization in Fe and NiFe due to reactive nitrogen sputtering is\ndiscussed in the present article.",
        "positive": "Modulation of crystal and electronic structures in topological\n  insulators by rare-earth doping: We study magnetotransport in a rare earth doped topological insulator,\nSm0.1Sb1.9Te3 single crystals, under magnetic fields up to 14 T. It is found\nthat that the crystals exhibit Shubnikov de Haas oscillations in their\nmagneto-transport behaviour at low temperatures and high magnetic fields. The\nSdH oscillations result from the mixed contributions of bulk and surface\nstates. We also investigate the SdH oscillations in different orientations of\nthe magnetic field, which reveals a three dimensional Fermi surface topology.\nBy fitting the oscillatory resistance with the Lifshitz Kosevich theory, we\ndraw a Landau-level fan diagram that displays the expected nontrivial phase. In\naddition, the density functional theory calculations shows that Sm doping\nchanges the crystal structure and electronic structure compared with pure\nSb2Te3. This work demonstrates that rare earth doping is an effective way to\nmanipulate the Fermi surface of topological insulators. Our results hold\npotential for the realization of exotic topological effects in magnetic\ntopological insulators."
    },
    {
        "anchor": "Anionic nickel and nitrogen effects in the chiral antiferromagnetic\n  antiperovskite Mn$_3$NiN: Magnetic antiperovskites, holding chiral noncollinear antiferromagnetic\nordering, have shown remarkable properties that cover from negative thermal\nexpansion to anomalous Hall effect. Nevertheless, details on the electronic\nstructure related to the oxidation states and the octahedral center's site\neffect are still scarce. Here, we show a theoretical study, based on\nfirst-principles calculations in the framework of the density-functional\ntheory, DFT, on the electronic details associated with the nitrogen site effect\ninto the structural, electronic, magnetic, and topological degrees of freedom.\nThus, we show that the nitrogen-vacancy increases the values of the anomalous\nHall conductivity and retains the chiral $\\Gamma_{4g}$ antiferromagnetic\nordering. Moreover, we reveal, based on the Bader charges and the electronic\nstructure analysis, the negative and positive oxidation states in the Ni and Mn\nsites, respectively. The latter is in agreement with the expected\n$A_3^{\\alpha+}B^{\\beta-}X^{\\delta-}$ oxidation states to satisfy the charge\nneutrality in the antiperovskites, but rare for transition metals. Finally, we\nextrapolate our findings on the oxidation states to several Mn$_3B$N compounds\nshowing that the antiperovskite structure is an ideal platform to encounter\nnegative oxidation states in metals sitting at the corner $B$-site.",
        "positive": "DFT Based LDA Study on Tailoring the Optical and Electrical Properties\n  of SnO and In-Doped SnO: In this paper, the structural, electronic and optical properties of\ntin-monoxide and the impact of Indium (In) doping into tin-monoxide are\ncomputed by Local Density Approximation (LDA) under density function theory\n(DFT) framework. The calculated bond length of Sn-O in tin-monoxide is 2.285\nangstrom and that deviates greater than 3 percent from the experimental value.\nThe Sn-O and In-O bond lengths in In-doped tin-monoxide are calculated to be\n2.3094 and 2.266 angstrom, respectively. Interestingly, the band gap of pure\ntin-monoxide is calculated to be 2.61 eV whereas it is significantly dropped\ndown to 2.00 eV in the case of In doped tin-monoxide. The Total Density of\nState (DOS), Partial DOS and electron density are depicted for tin-monoxide and\nIn-doped tin-monoxide films. As a consequence of In-doping static value of the\nrefractive index and real part of the dielectric function for tin-monoxide\ndecrease from 1.9 to 1.4 and 3.6 to 1.97, respectively. Therefore, In-doping\nenhances the properties of the tin-monoxide film, which may lead the material\nto be applied in future to develop electronic and opto-electronic devices."
    },
    {
        "anchor": "Origin of phase stability in Fe with long-period stacking order as an\n  intermediate phase in cyclic $\u03b3$-$\u03b5$ martensitic transformation: A class of Fe-Mn-Si-based alloys exhibits a reversible martensitic\ntransformation between the $\\gamma$ phase with a face-centered cubic~(fcc)\nstructure and an $\\epsilon$ phase with a hexagonal close-packed (hcp)\nstructure. During the deformation-induced $\\gamma$--$\\epsilon$ transformation,\nwe identified a phase that is different from the $\\epsilon$ phase. In this new\nphase, the electron diffraction spots are located at the 1/3 positions that\ncorrespond to the $\\{$0002$\\}$ plane of the $\\epsilon$ (hcp) phase with 2H\nstructure, which suggests long-period stacking order (LPSO). To understand the\nstacking pattern and explore the possible existence of an LPSO phase as an\nintermediate between the $\\gamma$ and $\\epsilon$ phases, the phase stability of\nvarious structural polytypes of iron was examined using first-principles\ncalculations with a spin-polarized form of the generalized gradient\napproximation in density functional theory. We found that an antiferromagnetic\nordered 6H$_2$ structure is the most stable among the candidate LPSO structures\nand is energetically close to the $\\epsilon$ phase, which suggests that the\nobserved LPSO-like phase adopts the 6H$_2$ structure. Furthermore, we\ndetermined that the phase stability can be attributed to the valley depth in\nthe density of states, close to the Fermi level.",
        "positive": "Interplay between Kitaev interaction and single ion anisotropy in\n  ferromagnetic CrI$_3$ and CrGeTe$_3$ monolayers: Magnetic anisotropy is crucially important for the stabilization of\ntwo-dimensional (2D) magnetism, which is rare in nature but highly desirable in\nspintronics and for advancing fundamental knowledge. Recent works on CrI$_3$\nand CrGeTe$_3$ monolayers not only led to observations of the long-time-sought\n2D ferromagnetism, but also revealed distinct magnetic anisotropy in the two\nsystems, namely Ising behavior for CrI$_3$ versus Heisenberg behavior for\nCrGeTe$_3$. Such magnetic difference strongly contrasts with structural and\nelectronic similarities of these two materials, and understanding it at a\nmicroscopic scale should be of large benefits. Here, first-principles\ncalculations are performed and analyzed to develop a simple Hamiltonian, to\ninvestigate magnetic anisotropy of CrI$_3$ and CrGeTe$_3$ monolayers. The\nanisotropic exchange coupling in both systems is surprisingly determined to be\nof Kitaev-type. Moreover, the interplay between this Kitaev interaction and\nsingle ion anisotropy (SIA) is found to naturally explain the different\nmagnetic behaviors of CrI$_3$ and CrGeTe$_3$. Finally, both the Kitaev\ninteraction and SIA are further found to be induced by spin-orbit coupling of\nthe heavy ligands (I of CrI$_3$ or Te of CrGeTe$_3$) rather than the commonly\nbelieved 3d magnetic Cr ions."
    },
    {
        "anchor": "Constructing Metallic Nanoroad on MoS2 Monolayer via Hydrogenation: Monolayer transition metal dichalcogenides recently emerge as a new family of\ntwo-dimensional material potentially suitable for numerous applications in\nelectronic and optoelectronic devices due to the presence of finite band gap.\nMany proposed applications require efficient transport of charge carriers\nwithin these semiconducting monolayers. However, how to construct a stable\nconducting nanoroad on these atomically thin semiconductors is still a\nchallenge. Here we demonstrate that hydrogenation on the surface of MoS2\nmonolayer induces a semiconductor-metal transition, and strip-patterned\nhydrogenation is able to generate a conducting nanoroad. The band-gap closing\narises from the formation of in-gap hybridized states mainly consisting of Mo\n4d orbitals, as well as the electron donation from hydrogen to the lattice\nhost. Ballistic conductance calculations reveal that such a nanoroad on the\nMoS2 surface exhibits an integer conductance, indicating small carrier\nscattering, and thus is ideal for serving as a conducting channel or\ninterconnect without compromising the mechanical and structural integrity of\nthe monolayer.",
        "positive": "Mechanism of the electro-optic effect and nonlinear optical\n  susceptibilities of some ferroelectrics: ab initio calculation: The nonlinear optical properties and electro-optic effects of some\noxygen-octahedric ferroelectrics are studied by the density functional theory\n(DFT) in the local density approximation (LDA) expressions based on first\nprinciple calculations without the scissor approximation. We present\ncalculations of the frequency- dependent complex dielectric function and the\nsecond harmonic generation response coefficient\n\\c{hi}(2)(-2{\\omega},{\\omega},{\\omega}) over a large frequency range in\ntetragonal and rhombohedral phases. The electronic linear electrooptic\nsusceptibility \\c{hi}(2) (-{\\omega},{\\omega},0) is also evaluated below the\nband gap. These results are based on a series of the LDA calculation using DFT.\nResults for \\c{hi}(2) (-{\\omega},{\\omega},0) are in agreement with the\nexperiment below the band gap and those for\n\\c{hi}(2)(-2{\\omega},{\\omega},{\\omega}) are compared with the experimental data\nwhere available."
    },
    {
        "anchor": "Phase stability of entropy stabilized oxides with the $\u03b1$-PbO$_2$\n  structure: The prediction of new high entropy oxides (HEOs) remains a profound challenge\ndue to their inherent chemical complexity. In this work, we combine\nexperimental and computational methods to search for new HEOs in the\ntetravalent $A$O$_2$ family, using exclusively $d^0$ and $d^{10}$ cations, and\nto explain the observed phase stability of the $\\alpha$-PbO$_2$ structure, as\nfound for the medium entropy oxide (Ti, Zr, Hf, Sn)O$_2$. Using a pairwise\napproach to approximate the mixing enthalpy, we confirm that $\\alpha$-PbO$_2$\nis the expected lowest energy structure for this material above other\ncandidates including rutile, baddeleyite, and fluorite structures. We also show\nthat no other five-component compound composed of the tetravalent cations\nconsidered here is expected to form under solid state synthesis conditions,\nwhich we verify experimentally. Ultimately, we conclude that the flexible\ngeometry of the $\\alpha$-PbO$_2$ structure can be used to understand its\nstability among tetravalent HEOs.",
        "positive": "Conductance switching, hysteresis, and magnetoresistance in organic\n  semiconductors: The controllability of charge transport through an organic molecular\nspin-valve system is theoretically investigated on the basis of a\nSu-Schrieffer-Heeger model combined with the non-equilibrium Green's function\nformalism. We show how the formation of polaron in the organic sub-structure\nleads to a hysteretic conductance switching, via sweeping either the bias\nvoltage or the electrochemical potential. We further obtain an exponential\ndependence of the magnetoresistance as a function of the applied bias voltage.\nThe implications of calculated results in relation to experiments and device\napplications are addressed and commented."
    },
    {
        "anchor": "Microfluidization of graphite and formulation of graphene-based\n  conductive inks: We report the exfoliation of graphite in aqueous solutions under high shear\nrate [$\\sim10^8s^{-1}$] turbulent flow conditions, with a 100\\% exfoliation\nyield. The material is stabilized without centrifugation at concentrations up\nto 100 g/L using carboxymethylcellulose sodium salt to formulate conductive\nprintable inks. The sheet resistance of blade coated films is\nbelow$\\sim2\\Omega/\\square$. This is a simple and scalable production route for\ngraphene-based conductive inks for large area printing in flexible electronics.",
        "positive": "Partitioning interatomic force constants for first-principles phonon\n  calculations: Applications to NaCl, PbTiO$_3$, monolayer CrI$_3$, and twisted\n  bilayer graphene: First-principles phonon calculations have been widely performed for studying\nvibrational properties of condensed matter, where the dynamical matrix is\ncommonly constructed via supercell force-constant calculations or the linear\nresponse approach. With different manners, a supercell can be introduced in\nboth methods. Unless the supercell is large enough, the interpolated phonon\nproperty highly depends on the shape and size of the supercell and the imposed\nperiodicity could give unphysical results that can be easily overlooked. Along\nthis line, the concept of partition of force constants is discussed, and\naddressed by NaCl, PbTiO$_3$, monolayer CrI$_3$, and twisted bilayer graphene\nas examples for illustrating the effects of the imposed supercell periodicity.\nTo diminish the unphysical effects, a simple method of partitioning force\nconstants, which relies only on the translational symmetry and interatomic\ndistances, is demonstrated to be able to deliver reasonable results. The\npartition method is also compatible with the mixed-space approach for\ndescribing LO-TO splitting. The proper partition is especially important for\nstudying moderate-size systems with low symmetry, such as two-dimensional\nmaterials on substrates, and useful for the implementation of phonon\ncalculations in first-principles packages using atomic basis functions, where\nsymmetry operations are usually not applied owing to the suitability for\nlarge-scale calculations."
    },
    {
        "anchor": "Magnetic proximity effect at the 3D topological insulator/magnetic\n  insulator interface: The magnetic proximity effect is a fundamental feature of heterostructures\ncomposed of layers of topological insulators and magnetic materials since it\nunderlies many potential applications in devices with novel quantum\nfunctionality. Within density functional theory we study magnetic proximity\neffect at the 3D topological insulator/magnetic insulator (TI/MI) interface in\nBi$_2$Se$_3$/MnSe(111) system as an example. We demonstrate that a gapped\nordinary bound state which spectrum depends on the interface potential arises\nin the immediate region of the interface. The gapped topological Dirac state\nalso arises in the system owing to relocation to deeper atomic layers of\ntopological insulator. The gap in the Dirac cone is originated from an\noverlapping of the topological and ordinary interfacial states. This result\nbeing also corroborated by the analytic model, is a key aspect of the magnetic\nproximity effect mechanism in the TI/MI structures.",
        "positive": "High-pressure lubricity at the meso- and nanoscale: The increase of sliding friction upon increasing load is a classic in the\nmacroscopic world. Here we discuss the possibility that friction rise might\nsometimes turn into a drop when, at the mesoscale and nanoscale, a confined\nlubricant film separating crystalline sliders undergoes strong layering and\nsolidification. Under pressure, transitions from N to N-1 layers may imply a\nchange of lateral periodicity of the crystallized lubricant sufficient to alter\nthe matching of crystal structures, influencing the ensuing friction jump. A\npressure-induced friction drop may occur as the shear gradient maximum switches\nfrom the lubricant middle, marked by strong stick-slip with or without shear\nmelting, to the crystalline slider-lubricant interface, characterized by smooth\nsuperlubric sliding. We present high pressure sliding simulations to display\nexamples of frictional drops, suggesting their possible relevance to the local\nbehavior in boundary lubrication."
    },
    {
        "anchor": "Thermodynamic dislocation theory: Bauschinger effect: The thermodynamic dislocation theory developed for non-uniform plastic\ndeformations is used here to simulate the stress-strain curves for crystals\nsubjected to anti-plane shear-controlled load reversal. We show that the\npresence of the positive back stress during the load reversal reduces the\nmagnitude of shear stress required to pull excess dislocations back to the\ncenter of the specimen. There, the excess dislocations of opposite signs meet\nand annihilate each other leading to the Bauschinger effect.",
        "positive": "Half-metallicity and giant magneto-optical Kerr effect in N-doped\n  NaTaO$_3$: We employ density functional theory using the modified Becke-Johnson (mBJ)\napproach to investigate the electronic and magneto-optical properties of\nN-doped NaTaO$_3$. The mBJ results reveal a half metallic nature of NaTaO$_2$N,\nin contrast to results obtained by the generalized gradient approximation. We\nfind a giant polar Kerr rotation of 2.16$^{\\circ}$ at 725 nm wave length\n(visible region), which is high as compared to other half metallic perovskites\nas well as to the prototypical half metal PtMnSb."
    },
    {
        "anchor": "Unraveling the spin reorientation process in rare earth perovskite\n  PrFe0.1Cr0.9O3: Ultrafast spin control plays a pivotal role in condensed matter physics. In\nthis study, we analyzed the macroscopic magnetization of the PrFe0.1Cr0.9O3\nsystem by molecular field model fitting. And the whole process of system spin\nreorientation is accurately calculated in the fitting process. It is found\nthat, unlike the rare-earth perovskites we have previously studied,\nPrFe0.1Cr0.9O3 exhibits spin-reversion properties during the reorientation\nprocess. This research will lay a theoretical foundation for precise spin\ncontrol in the future.",
        "positive": "A new topological semimetal with iso-energetic Weyl fermions in TaAs\n  under high pressure: TaAs as one of the experimentally discovered topological Weyl semimetal has\nattracted intense interests recently. The ambient TaAs has two types of Weyl\nnodes which are not on the same energy level. As an effective way to tune\nlattice parameters and electronic interactions, high pressure is becoming a\nsignificant tool to explore new materials as well as their exotic states.\nTherefore, it is highly interesting to investigate the behaviors of topological\nWeyl fermions and possible structural phase transitions in TaAs under pressure.\nHere, with a combination of ab initio calculations and crystal structure\nprediction techniques, a new hexagonal P-6m2 phase is predicted in TaAs at\npressure around 14 GPa. Surprisingly, this new phase is a topological semimetal\nwith only single set of Weyl nodes exactly on the same energy level. The phase\ntransition pressure from the experimental measurements, including electrical\ntransport measurements and Raman spectroscopy, agrees with our theoretical\nprediction reasonably. Moreover, the P-6m2 phase seems to be quenched\nrecoverable to ambient pressure, which increases the possibilities of further\nstudy on the exotic behaviors of single set of Weyl fermions, such as the\ninterplay between surface states and other properties."
    },
    {
        "anchor": "Tuning magnetic and optical properties through strain in epitaxial\n  LaCrO3 thin films: We report on the effect of epitaxial strain on magnetic and optical\nproperties of perovskite LaCrO3 (LCO) single crystal thin films. Epitaxial LCO\nthin films are grown by pulsed laser deposition on proper choice of substrates\nto impose different strain states. A combined experimental and theoretical\napproach is used to demonstrate the direct correlation between lattice-strain\nand functional properties. The magnetization results show that the lattice\nanisotropy plays a critical role in controlling the magnetic behavior of LCO\nfilms. The strain induced tetragonality in the film lattice strongly affects\nthe optical transitions and charge transfer gap in LCO. This study opens new\npossibilities to tailoring the functional properties of LCO and related\nmaterials by strain engineering in epitaxial growth.",
        "positive": "Valence-band structure of ferromagnetic semiconductor (InGaMn)As: To clarify the whole picture of the valence-band structures of prototype\nferromagnetic semiconductors (III,Mn)As (III: In and Ga), we perform systematic\nexperiments of the resonant tunneling spectroscopy on [(In_0.53Ga_0.47)_1-x\nMn_x]As (x=0.06-0.15) and In_0.87Mn_0.13As grown on AlAs/ In_0.53Ga_0.47As:Be/\np+InP(001). We show that the valence band of InGaMnAs almost remains unchanged\nfrom that of the host semiconductor InGaAs, that the Fermi level exists in the\nband gap, and that the p-d exchange splitting in the valence band is negligibly\nsmall in (InGaMn)As. In the In0.87Mn0.13As sample, although the resonant peaks\nare very weak due to the large strain induced by the lattice mismatch between\nInP and InMnAs, our results also indicate that the Fermi level exists in the\nband gap and that the p-d exchange splitting in the valence band is negligibly\nsmall. These results are quite similar to those of GaMnAs obtained by the same\nmethod, meaning that there are no holes in the valence band, and that the\nimpurity-band holes dominate the transport and magnetism both in the InGaMnAs\nand In_0.87Mn_0.13As films. This band picture of (III,Mn)As is remarkably\ndifferent from that of II-VI-based diluted magnetic semiconductors."
    },
    {
        "anchor": "Evaluating approaches for on-the-fly machine learning interatomic\n  potential for activated mechanisms sampling with the activation-relaxation\n  technique nouveau: In the last few years, much efforts have gone into developing universal\nmachine-learning potentials able to describe interactions for a wide range of\nstructures and phases. Yet, as attention turns to more complex materials\nincluding alloys, disordered and heterogeneous systems, the challenge of\nproviding reliable description for all possible environment become ever more\ncostly. In this work, we evaluate the benefits of using specific versus general\npotentials for the study of activated mechanisms in solid-state materials. More\nspecifically, we tests three machine-learning fitting approaches using the\nmoment-tensor potential to reproduce a reference potential when exploring the\nenergy landscape around a vacancy in Stillinger-Weber silicon crystal and\nsilicon-germanium zincblende structure using the activation-relaxation\ntechnique nouveau (ARTn). We find that a a targeted on-the-fly approach\nspecific and integrated to ARTn generates the highest precision on the\nenergetic and geometry of activated barriers, while remaining cost-effective.\nThis approach expands the type of problems that can be addressed with\nhigh-accuracy ML potentials.",
        "positive": "Stability of boron-doped graphene/copper interface: DFT, XPS and OSEE\n  studies: Two different types of boron-doped graphene/copper interfaces synthesized\nusing two different flow rates of Ar through the bubbler containing the boron\nsource were studied. X-ray photoelectron spectra (XPS) and optically stimulated\nelectron emission (OSEE) measurements have demonstrated that boron-doped\ngraphene coating provides a high corrosion resistivity of Cu-substrate with the\nlight traces of the oxidation of carbon cover. The density functional theory\ncalculations suggest that for the case of substitutional (graphitic)\nboron-defect only the oxidation near boron impurity is energetically favorable\nand creation of the vacancies that can induce the oxidation of copper substrate\nis energetically unfavorable. In the case of non-graphitic boron defects\noxidation of the area, a nearby impurity is metastable that not only prevent\noxidation but makes boron-doped graphene. Modeling of oxygen reduction reaction\ndemonstrates high catalytic performance of these materials."
    },
    {
        "anchor": "Molecular beam epitaxy of InAs nanowires in SiO2 nanotube templates:\n  challenges and prospects for integration of III-Vs on Si: Guided growth of semiconductor nanowires in nanotube templates has been\nconsidered as a potential platform for reproducible integration of III-Vs on\nsilicon or other mismatched substrates. Herein, we report on the challenges and\nprospects of molecular beam epitaxy of InAs nanowires on SiO2/Si nanotube\ntemplates. We show how and under which conditions the nanowire growth is\ninitiated by In-assisted vapor-liquid-solid growth enabled by the local\nconditions inside the nanotube template. The conditions for high yield of\nvertical nanowires are investigated in terms of the nanotube depth, diameter\nand V/III flux ratios. We present a model that further substantiates our\nfindings. This work opens new perspectives for monolithic integration of III-Vs\non the silicon platform enabling new applications in the electronics,\noptoelectronics and energy harvesting arena.",
        "positive": "Elucidating the Voltage Controlled Magnetic Anisotropy: Voltage controlled magnetic anisotropy (VCMA) is an efficient way to\nmanipulate the magnetization states in nanomagnets, promising for low-power\nspintronic applications. The underlying physical mechanism for VCMA is known to\ninvolve a change in the d-orbital occupation on the transition metal interface\natoms with an applied electric field. However, a simple qualitative picture of\nhow this occupation controls the magnetocrystalline anisotropy (MCA) and even\nwhy in certain cases the MCA has opposite sign still remains elusive. In this\npaper, we exploit a simple model of orbital populations to elucidate a number\nof features typical for the interface MCA and the effect of electric field on\nit, for 3d transition metal thin films used in magnetic tunnel junctions. We\nfind that in all considered cases including the Fe (001) surface, clean\nFe1-xCox(001)/MgO interface and oxidized Fe(001)/MgO interface, the effects of\nalloying and electric field enhance the MCA energy with electron depletion\nwhich is largely explained by the occupancy of the minority-spin dxz,yz\norbitals. On the other hand, the hole doped Fe(001) exhibits an inverse VCMA,\nwhere the MCA enhancement is achieved when electrons are accumulated at the Fe\n(001)/MgO interface with applied electric field. In this regime we predict a\nsignificantly enhanced VCMA which exceeds 1pJ/Vm. Realizing this regime\nexperimentally may be favorable for a practical purpose of voltage driven\nmagnetization reversal."
    },
    {
        "anchor": "Establishing quasi-linear quadrupole functional topology by\n  oxygen-vacancy engineering at a ferroelectric domain wall: Oxygen vacancies in two-dimensional metal-oxide structures garner much\nattention due to unique conductive, magnetic and even superconductive\nfunctionalities they induce. Ferroelectric domain walls have been a prominent\nrecent example because they serve as a hub for topological defects that enable\nunusual symmetries and are relevant for low-energy switching technologies.\nHowever, owing to the light weight of oxygen atoms and localized effects of\ntheir vacancies, the atomic-scale electrical and mechanical influence of oxygen\nvacancies has remained elusive. Here, stable individual oxygen vacancies were\nfound and engineered in situ at domain walls of seminal titanate perovskite\nferroics. The atomic-scale strain, electric-field, charge and dipole-moment\ndistribution around these vacancies were characterized by combining advanced\ntransmission electron microscopy and first-principle methodologies. 3-5 %\ntensile strain was observed at the immediate surrounding unit cells of the\nvacancies. The dipole-moment distribution around the vacancy was found to be an\nalternating head-to-head $-$ tail-to-tail $-$ head-to-head structure, giving\nrise to a quasi-linear quadrupole topology. Reduction of the nearby Ti ion as\nwell as enhanced charging and electric-field concentration near the vacancy\nconfirmed the quadrupole structure and illustrated its local effects on the\nelectrical and structural properties. Significant intra-band states were found\nin the unit cell of the vacancies, proposing a meaningful domain-wall\nconductivity. Oxygen-vacancy engineering and controllable quadrupoles that\nenable pre-determining both atomic-scale and global functional properties offer\na promising platform of electro-mechanical topological solitons and device\nminiaturization in metal oxides.",
        "positive": "TopoTB: A software package for calculating the electronic structure and\n  topological properties of the tight-binding model: We present TopoTB, a software package written in the Mathematica language,\ndesigned to compute electronic structures, topological properties, and phase\ndiagrams based on tight-binding models. TopoTB is user-friendly, with an\ninteractive user interface that enables the tuning of model parameters for\nfitting the target energy bands in a WYSIWYG way. In addition, TopoTB also\nincludes functionalities for processing results from Density Functional Theory\ncalculations. The outputs of TopoTB are rich and readable, and they can be\ndisplayed in various styles. These features make TopoTB a useful tool for the\ntheoretical study of materials."
    },
    {
        "anchor": "Iterative peak-fitting of frequency-domain data via deep convolution\n  neural networks: High-throughput material screening for the discovery and design of novel\nfunctional materials requires automatized analyses of theoretical and\nexperimental data. Here we study the subject of human-free analyses of\none-dimensional spectroscopic data, {\\it e.g.} in the frequency domain, via\nemploying deep convolution neural network. Specifically, we trained various\ndeep convolution neural network and benchmarked their performance in\ndecomposing one-dimensional noisy data into multiple nonorthogonal peaks in an\niterative manner, after which a conventional basin-hopping algorithm was\napplied to further reduce residual fitting error. Among six different network\narchitectures, a variant of \"Squeeze-and-excitation\" network (SENet) structure\nthat we first propose in this study shows the best performance. Dependency of\ntraining performance with respect to the choice of the loss function is also\ndiscussed. We conclude by applying our modified SENet model to experimental\nphotoemission spectra of graphene, MoS$_2$, and WS$_2$ and address its\npotential applications and limitations.",
        "positive": "Spectral and optical properties of Ag$_3$Au(Se$_2$,Te$_2$) and dark\n  matter detection: In this work we study the electronic structure of Ag${}_3$AuSe${}_2$ and\nAg${}_3$AuTe${}_2$, two chiral insulators whose gap can be tuned through small\nchanges in the lattice parameter by applying hydrostatic pressure or choosing\ndifferent growth protocols. Based on first principles calculations we compute\ntheir band structure for different values of the lattice parameters and show\nthat while Ag${}_3$AuSe${}_2$ retains its direct narrow gap at the $\\Gamma$\npoint, Ag${}_3$AuTe${}_2$ can turn into a metal. Focusing on Ag${}_3$AuSe${}_2$\nwe derive a low energy model around $\\Gamma$ using group theory, which we use\nto calculate the optical conductivity for different values of the lattice\nconstant. We discuss our results in the context of detection of light dark\nmatter particles, which have masses of the order of a $k$eV, and conclude that\nAg${}_3$AuSe${}_2$ satisfies three important requirements for a suitable\ndetector: small Fermi velocities, $m$eV band gap and low photon screening. Our\nwork motivates the growth of high-quality and large samples of\nAg${}_3$AuSe${}_2$ to be used as target materials in dark matter detectors."
    },
    {
        "anchor": "Towards a robust ad-hoc data correction approach that yields reliable\n  atomic pair distribution functions from powder diffraction data: We examine the equations to obtain atomic pair distribution functions (PDFs)\nfrom x-ray, neutron and electron powder diffraction data with a view to\nobtaining reliable and accurate PDFs from the raw data using a largely \\emph{ad\nhoc} correction process. We find that this should be possible under certain\ncircumstances that hold, to a reasonably good approximation, in many modern\nexperiments. We describe a variational approach that could be applied to find\ndata correction parameters that is highly automatable and should require little\nin the way of user inputs yet results in quantitatively reliable PDFs, modulo\nunknown scale factors that are often not of scientific interest when profile\nfitting models are applied to the data with scale-factor as a parameter. We\nhave worked on a particular implementation of these ideas and demonstrate that\nit yields PDFs that are of comparable quality to those obtained with existing\nx-ray data reduction program PDFgetX2. This opens the door to rapid and highly\nautomated processing of raw data to obtain PDFs.",
        "positive": "Anomalous Phonon Renormalization in Single Crystal of Silicon: The temperature dependence of the first-order phonon mode of single crystal\nof Silicon (Si) is determined by Raman scattering in a broad temperature range\nof 4-623 K. Our studies reveal the anomalous red-shift of the Raman active\nphonon mode at temperature (~ 50 K) attributed to the anomalous expansion of Si\nin the low temperature region. Silicon shows negative thermal expansion below\n120 K, however, odd behaviour is also observed at very low temperatures i.e.,\nsoftening of the Si crystal is detected below 40 K. This peculiar behaviour of\nSi is described by the anomalous phonon anharmonicity observed at low\ntemperature."
    },
    {
        "anchor": "Experimental probing of exchange interactions between localized spins in\n  the dilute magnetic insulator (Ga,Mn)N: The sign, magnitude, and range of the exchange couplings between pairs of Mn\nions is determined for (Ga,Mn)N and (Ga,Mn)N:Si with x < 3%. The samples have\nbeen grown by metalorganic vapor phase epitaxy and characterized by\nsecondary-ion mass spectroscopy; high-resolution transmission electron\nmicroscopy with capabilities allowing for chemical analysis, including the\nannular dark-field mode and electron energy loss spectroscopy; high-resolution\nand synchrotron x-ray diffraction; synchrotron extended x-ray absorption\nfine-structure; synchrotron x-ray absorption near-edge structure; infra-red\noptics and electron spin resonance. The results of high resolution magnetic\nmeasurements and their quantitative interpretation have allowed to verify a\nseries of ab initio predictions on the possibility of ferromagnetism in dilute\nmagnetic insulators and to demonstrate that the interaction changes from\nferromagnetic to antiferromagnetic when the charge state of the Mn ions is\nreduced from 3+ to 2+.",
        "positive": "Fast, efficient, and accurate dielectric screening using a local,\n  real-space approach: Various many-body perturbation theory techniques for calculating electron\nbehavior rely on {\\it W}, the screened Coulomb interaction. Computing {\\it W}\nrequires complete knowledge of the dielectric response of the electronic\nsystem, and the fidelity of the calculated dielectric response limits the\nreliability of predicted electronic and structural properties. As a\nsimplification, calculations often begin with the random-phase approximation\n(RPA). However, even RPA calculations are costly and scale poorly, typically as\n$N^4$ ($N$ representing the system size). A local approach has been shown to be\nefficient while maintaining accuracy for screening core-level excitations\n[Ultramicroscopy {\\bf 106}, 986 (2006)]. We extend this method to valence-level\nexcitations. We present improvements to the accuracy and execution of this\nscheme, including reconstruction of the all-electron character of the\npseudopotential-based wave functions, improved $N^2\\log N$ scaling, and a\nparallelized implementation. We discuss applications to Bethe-Salpeter equation\n(BSE) calculations of core and valence spectroscopies."
    },
    {
        "anchor": "Mn(Pt$_{1-x}$Pd$_{x}$)$_5$P: Isovalent Tuning of Mn Sublattice Magnetic\n  Order: We report the growth and characterization of MnPd$_5$P, a ferromagnet with\nT$_C$ $\\approx$ 295 K, and conduct a substitutional study with its\nantiferromagnetic analogue MnPt$_5$P. We grow single crystals of MnPd$_5$P and\nMn(Pt$_{1-x}$Pd$_x$)$_5$P by adding Mn into (Pt$_{1-x}$Pd$_{x}$)-P based melts.\nAll compounds in the family adopt the layered anti-CeCoIn$_5$ structure with\nspace group P4/mmm, and EDS and XRD results indicate that MnPt$_5$P and\nMnPd$_5$P form a solid solution. Based on magnetization and resistance data, we\nconstruct a T-x phase diagram for Mn(Pt$_{1-x}$Pd$_x$)$_5$P and demonstrate the\nantiferromagnetic order found in MnPt$_5$P is extraordinarily sensitive to Pd\nsubstitution. At low Pd fractions (x $<$ 0.010), the single antiferromagnetic\ntransition in pure MnPt$_5$P splits into a higher temperature ferromagnetic\ntransition followed on cooling by a lower temperature ferromagnetic to\nantiferromagnetic transition and then by a re-entrant antiferromagnetic to\nferromagnetic transition at lower temperatures. The antiferromagnetic region\nmakes up a bubble that persists to x $\\approx$ 0.009 for T $\\approx$ 150 K,\nwith all samples x $<$ 0.009 recovering their initial ferromagnetic state with\nfurther cooling to base temperature. Over the same low x range we find a\nnon-monotonic change in the room temperature unit cell volume, further\nsuggesting that pure MnPt$_5$P is close to an instability. Once x $>$ 0.010,\nMn(Pt$_{1-x}$Pd$_x$)$_5$P undergoes a single ferromagnetic transition. The\nCurie temperature increases rapidly with x, rising from T$_C$ $\\approx$ 197 K\nat x = 0.013 to a maximum of T$_C$ $\\approx$ 312 K for x $\\approx$ 0.62, and\nthen falls back to T$_C$ $\\approx$ 295 K for pure MnPd$_5$P (x = 1). Given that\nPt and Pd are isoelectronic, this work raises questions as to the origin of the\nextreme sensitivity of the magnetic ground state in MnPt$_5$P upon introducing\nPd.",
        "positive": "Photoluminescence from localized states in disordered indium nitride: Photoluminescence spectra from disordered InN were studied in very high\nmagnetic fields. The samples had Gaussian spectra with low temperature emission\npeaks at 0.82 and 0.98eV respectively. The average spatial extent of the\nexcitonic wave functions, inferred from the diamagnetic shift, is only 2-3nm.\nThis shows that the recombination is from an ensemble of highly localized\nstates within a landscape of a smooth (classical) disorder potential of\nstrength of the order of 10meV. The anomalies in the temperature dependence of\nthe photoluminescence peak and linewidth give further support to the picture of\ntrapped photoexcited carriers."
    },
    {
        "anchor": "Control of domain states in rhombohedral PZT films via misfit strains\n  and surface charges: Using the Landau-Ginzburg-Devonshire theory, an influence of the misfit\nstrain and surface screening charges, as well as the role of the flexoelectric\neffect, have been studied by numerical modelling in the case of a rhombohedral\nlead zirconate-titanate ferroelectric/ferroelastic thin film with an\nanisotropic misfit produced by a substrate. It was established that the\nmagnitude and sign of the misfit strain influence the domain structure and\npredominant directions of the polarization vector, providing misfit-dependent\nphases with different favourable polarization components. Whilst strong enough\ncompressive misfit strains favour a phase with an orthorhombic-like\npolarization directions, strong tensile misfits only yield in-plane\npolarization components. The strength of surface screening is seen to condition\nthe existence of closure domain structures and, by increasing, supports the\nsingle-domain state depending on the value of the misfit strain. The\nflexoelectric effect exhibits a weak influence on the phase diagram of\nmulti-domain states when compared with the phase diagram of single-domain\nstates. Its effect, however, becomes significant in the case of skyrmion\ntopological states, which spontaneously form near the film surface when\ncompressive misfit strains are applied. Cooperative influence of the misfit\nstrain, surface screening charges and temperature can set a thin rhombohedral\nferroelectric film into a number of different polar and structural states,\nwhereby the role of the flexoelectric effect is pronounced for topologically\nnontrivial structures.",
        "positive": "Totimorphic structures for space application: We propose to use a recently introduced Totimorphic metamaterial for\nconstructing morphable space structures. As a first step to investigate the\nfeasibility of this concept, we present a method for morphing such structures\nautonomously between different shapes using physically plausible actuations,\nguaranteeing that the material traverses through valid configurations only\nwhile morphing. With this work, we aim to lay a foundation for exploring a\npromising and novel class of multi-functional, reconfigurable space structures."
    },
    {
        "anchor": "1.5 million materials narratives generated by chatbots: The advent of artificial intelligence (AI) has enabled a comprehensive\nexploration of materials for various applications. However, AI models often\nprioritize frequently encountered materials in the scientific literature,\nlimiting the selection of suitable candidates based on inherent physical and\nchemical properties. To address this imbalance, we have generated a dataset of\n1,494,017 natural language-material paragraphs based on combined OQMD,\nMaterials Project, JARVIS, COD and AFLOW2 databases, which are dominated by ab\ninitio calculations and tend to be much more evenly distributed on the periodic\ntable. The generated text narratives were then polled and scored by both human\nexperts and ChatGPT-4, based on three rubrics: technical accuracy, language and\nstructure, and relevance and depth of content, showing similar scores but with\nhuman-scored depth of content being the most lagging. The merger of\nmulti-modality data sources and large language model (LLM) holds immense\npotential for AI frameworks to help the exploration and discovery of\nsolid-state materials for specific applications.",
        "positive": "The Conformational Space of a Flexible Amino Acid at Metallic Surfaces: In interfaces between inorganic and biological materials relevant for\ntechnological applications, the general challenge of structure determination is\nexacerbated by the high flexibility of bioorganic components, chemical bonding,\nand charge rearrangement at the interface. In this paper, we investigate a\nchemically complex building block, namely, the arginine (Arg) amino-acid\ninterfaced with Cu, Ag and Au (111) surfaces. We investigate how the\nenvironment changes the accessible conformational space of this amino acid, by\nbuilding and analyzing a database of thousands of structures optimized with the\nPBE functional including screened pairwise van der Waals interactions. When in\ncontact with metallic surfaces, the accessible space for Arg is dramatically\nreduced, while the one for Arg-H$^+$ is instead increased if compared to the\ngas-phase. This is explained by the formation of strong bonds between Arg and\nthe surfaces and by their absence and charge screening on Arg-H$^+$ upon\nadsorption. We also observe protonation-dependent stereoselective binding of\nthe amino acid to the metal surfaces: Arg adsorbs with its chiral C$_\\alpha$H\ncenter pointing H away from the surfaces while Arg-H$^+$ adsorbs with H\npointing toward the surface."
    },
    {
        "anchor": "Infrared optical properties of $\u03b1$ quartz by molecular dynamics\n  simulations: This paper is concerned with theoretical estimates of the refractive--index\ncurves for quartz, obtained by the Kubo formul\\ae\\ in the classical\napproximation, through MD simulations for the motions of the ions. Two\nobjectives are considered. The first one is to understand the role of\nnonlinearities in situations where they are very large, as at the\n$\\alpha$--$\\beta$ structural phase transition. We show that on the one hand\nthey don't play an essential role in connection with the form of the spectra in\nthe infrared. On the other hand they play an essential role in introducing a\nchaoticity which involves a definite normal mode. This might explain why that\nmode is Raman active in the $\\alpha$ phase, but not in the $\\beta$ phase. The\nsecond objective concerns whether it is possible in a microscopic model to\nobtain normal mode frequencies, or peak frequencies in the optical spectra,\nthat are in good agreement with the experimental data for quartz.\nNotwithstanding a lot of effort, we were unable to find results agreeing better\nthan about 6%, as apparently also occurs in the whole available literature. We\ninterpret this fact as indicating that some essential qualitative feature is\nlacking in all models which consider, as the present one, only short--range\nrepulsive potentials and unretarded long--range electric forces.",
        "positive": "Ab-initio insights into the mechanical, phonon, bonding, electronic,\n  optical and thermal properties of hexagonal W2N3 for potential applications: We investigated the structural, elastic, electronic, vibrational, optical,\nthermodynamic and a number of thermophysical properties of W2N3 in this study\nusing DFT based formalisms. The mechanical and dynamical stabilities have been\nconfirmed. The Pugh and Poisson ratios are located quite close to the brittle\nto ductile borderline. The electronic band structure and energy density of\nstates show metallic behavior. The Fermi surface features are investigated. The\nanalysis of charge density distribution map clearly shows that W atoms have\ncomparatively high electron density around than the N atoms. Presence of\ncovalent bondings are anticipated. High melting temperature and high phonon\nthermal conductivity at room temperature of W2N3 imply that the compound has\npotential to be used as a heat sink system. The optical characteristics\ndemonstrate anisotropy for W2N3. The compound can be used in optoelectronic\ndevice applications due to its high absorption coefficient and low reflectivity\nin the visible to ultraviolet spectrum. Furthermore, the quasiharmonic Debye\nmodel is used to examine temperature and pressure dependent thermal\ncharacteristics for the first time."
    },
    {
        "anchor": "Terahertz wave generation via optical rectification from multiferroic\n  BiFeO3: We detected broadband coherent terahertz (THz) emission from multiferroic\nBiFeO3 after illuminating a high-quality bulk single ferroelectric domain\ncrystal with a ~100 fs optical pulse. The dependence of the emitted THz\nwaveform on the energy and polarization of the optical pulse is consistent with\nthe optical rectification mechanism of THz emission. The THz emission provides\na sensitive probe of the electric polarization state of BiFeO3, enabling\napplications in ferroelectric memories and ferroelectric domain imaging. We\nalso report room-temperature THz optical constants of BiFeO3.",
        "positive": "Prediction and Characterization of Two-Dimensional Zn2VN3: A two-dimensional (2D) monolayer of a novel ternary nitride Zn2VN3 is\ncomputationally designed, and its dynamical and thermal stability is\ndemonstrated. A synthesis strategy is proposed based on experimental works on\nproduction of ternary nitride thin films, calculations of formation and\nexfoliation energies, and ab initio molecular dynamics simulations. A\ncomprehensive characterization of 2D Zn2VN3, including investigation of its\noptoelectronic and mechanical properties, is conducted. It is shown that 2D\nZn2VN3 is a semiconductor with an indirect band gap of 2.75 eV and a high work\nfunction of 5.27 eV. Its light absorption covers visible and ultraviolet\nregions. The band gap of 2D Zn2VN3 is found to be well tunable by applied\nstrain. At the same time 2D Zn2VN3 possesses high stability against mechanical\nloads, point defects, and environmental impacts. Considering the unique\nproperties found for 2D Zn2VN3, it can be used for application in\noptoelectronic and straintronic nanodevices."
    },
    {
        "anchor": "Direct Determination of Exciton Wave Function Amplitudes by the\n  Momentum-Resolved Photo-Electron Emission Experiment: We study conceptional problems of a photo-electron emission (PEE) process\nfrom a free exciton in insulating crystals. In this PEE process, only the\nelectron constituting the exciton is suddenly emitted out of the crystal, while\nthe hole constituting the exciton is still left inside and forced to be\nrecoiled back to its original valence band. This recoil on the hole is surely\nreflected in the spectrum of the PEE with a statistical distribution along the\nmomentum-energy curve of the valence band. This distribution is nothing but the\nsquare of the exciton wave function amplitude, since it shows how the electron\nand the hole are originally bound together. Thus, the momentum-resolved PEE can\ndirectly determine the exciton wave function. These problems are clarified,\ntaking the $\\Gamma$ and the saddle point excitons in GaAs, as typical examples.\nNew PEE experiments are also suggested.",
        "positive": "Au-Ag-Cu nano-alloys: tailoring of permittivity: Precious metal alloys enables new possibilities to tailor materials for\nspecific optical functions. Here we present a systematic study of the effects\nof a nanoscale alloying on the permittivity of Au-Ag-Cu metals at 38 different\natomic mixing ratios. The permittivity was measured and analyzed numerically by\napplying the Drude model. X-ray diffraction (XRD) revealed the face centered\ncubic lattice of the alloys. Both, optical spectra and XRD results point\ntowards an equivalent composition-dependent electron scattering behavior.\nCorrelation between the fundamental structural parameters of alloys and the\nresulting optical properties is elucidated. Plasmonic properties of the\nAu-Ag-Cu alloy nanoparticles were investigated by numerical simulations.\nGuidelines for designing plasmonic response of nano- structures and their\npatterns are presented from the material science perspective."
    },
    {
        "anchor": "Non-local Gilbert damping tensor within the torque-torque correlation\n  model: An essential property of magnetic devices is the relaxation rate in magnetic\nswitching which depends strongly on the damping in the magnetisation dynamics.\nIt was recently measured that damping depends on the magnetic texture and,\nconsequently, is a non-local quantity. The damping enters the\nLandau-Lifshitz-Gilbert equation as the phenomenological Gilbert damping\nparameter $\\alpha$, that does not, in a straight forward formulation, account\nfor non-locality. Efforts were spent recently to obtain Gilbert damping from\nfirst principles for magnons of wave vector $\\mathbf{q}$. However, to the best\nof our knowledge, there is no report about real space non-local Gilbert damping\n$\\alpha_{ij}$. Here, a torque-torque correlation model based on a tight binding\napproach is applied to the bulk elemental itinerant magnets and it predicts\nsignificant off-site Gilbert damping contributions, that could be also\nnegative. Supported by atomistic magnetisation dynamics simulations we reveal\nthe importance of the non-local Gilbert damping in atomistic magnetisation\ndynamics. This study gives a deeper understanding of the dynamics of the\nmagnetic moments and dissipation processes in real magnetic materials. Ways of\nmanipulating non-local damping are explored, either by temperature, material's\ndoping or strain.",
        "positive": "Effect of Element Doping and Substitution on the Electronic Structure\n  and Macroscopic Magnetic Properties of SmFe$_{12}$-based Compounds: The mechanisms underlying the enhancement of magnetic anisotropies (MAs) of\nSm ions, owing to valence electrons at the Sm site and the screened nuclear\ncharges of ligands, are clarified using a detailed analysis of crystal fields\n(CF). In order to investigate the finite-temperature magnetic properties, we\ndeveloped an effective spin model for SmFe$_{12}X$ ($X$=H, B, C, and N) and\nSmFe$_{11}M$ ($M$=Ti, V, and Co), where the magnetic moments, CF parameters,\nand exchange fields were determined by first-principle calculations. Using this\nmodel, the MA constants and magnetization curves at finite temperatures were\ninvestigated using a recently introduced analytical method [T. Yoshioka, H.\nTsuchiura, and P. Nov\\'ak, Phys. Rev. B {\\bf 102}, 184410 (2020)]. In\nSmFe$_{12}X$, the doped light elements $X$ are assumed to be at the $2b$ site,\nand in SmFe$_{11}M$, the substitution site of Fe is systematically investigated\nfor all inequivalent $8f$, $8i$, and $8j$ sites. We found that the first-order\nMA constant $K_1$ is increased by a factor of about two when hydrogen is doped\nto the $2b$ site and when Fe is replaced by Ti or V at the $8j$ site, owing to\nthe attraction of the prolate $4f$ electron cloud to the screened positive\ncharges of the surrounding ligand ions. We found that when Fe is replaced by\nCo, the MA increases at all temperatures regardless of the substitution site.\nThe substituted Co attracts electrons, which reduces the electron density in\nthe region from the Sm site to the empty $2b$ site. This causes the $4f$\nelectron cloud at the Sm site to be fixed along the $c$-axis direction, which\nimproves the MA. The calculated temperature dependence of $K_1(T)$ and $K_2(T)$\nin SmFe$_{11}$Co qualitatively reproduces the experimental results in the case\nof Sm(Co$_x$Fe$_{1-x}$)$_{12}$ for $x$=0.1 and 0.07."
    },
    {
        "anchor": "py4DSTEM: a software package for multimodal analysis of four-dimensional\n  scanning transmission electron microscopy datasets: Scanning transmission electron microscopy (STEM) allows for imaging,\ndiffraction, and spectroscopy of materials on length scales ranging from\nmicrons to atoms. By using a high-speed, direct electron detector, it is now\npossible to record a full 2D image of the diffracted electron beam at each\nprobe position, typically a 2D grid of probe positions. These 4D-STEM datasets\nare rich in information, including signatures of the local structure,\norientation, deformation, electromagnetic fields and other sample-dependent\nproperties. However, extracting this information requires complex analysis\npipelines, from data wrangling to calibration to analysis to visualization, all\nwhile maintaining robustness against imaging distortions and artifacts. In this\npaper, we present py4DSTEM, an analysis toolkit for measuring material\nproperties from 4D-STEM datasets, written in the Python language and released\nwith an open source license. We describe the algorithmic steps for dataset\ncalibration and various 4D-STEM property measurements in detail, and present\nresults from several experimental datasets. We have also implemented a simple\nand universal file format appropriate for electron microscopy data in py4DSTEM,\nwhich uses the open source HDF5 standard. We hope this tool will benefit the\nresearch community, helps to move the developing standards for data and\ncomputational methods in electron microscopy, and invite the community to\ncontribute to this ongoing, fully open-source project.",
        "positive": "Edge-driven transition in surface structure of nanoscale silicon: We present an ab initio exploration of the phenomena which will become\nimportant for freestanding structures of silicon as they are realized on the\nnanoscale. We find that not only surface but also edge effects are important\nconsiderations in structures of dimensions on the order of 3 nm. Specifically,\nfor long nanoscale silicon bars, we find two competing low-energy\nreconstructions with a transition from one to the other as the cross section of\nthe bar decreases. We predict that this size-dependent phase transition has a\nsignature in the electronic structure of the bar but little effect on elastic\nproperties."
    },
    {
        "anchor": "Boron films produced by high energy Pulsed Laser Deposition: Micron-thick boron films have been deposited by Pulsed Laser Deposition in\nvacuum on several substrates at room temperature. The use of high energy pulses\n(>700 mJ) results in the deposition of smooth coatings with low oxygen uptake\neven at base pressures of 10$^{-4}$ - 10$^{-3}$ Pa. A detailed structural\nanalysis, by X-Ray Diffraction and Raman, allowed to assess the amorphous\nnature of the deposited films as well as to determine the base pressure that\nprevents boron oxide formation. In addition the crystallization dynamics has\nbeen characterized showing that film crystallinity already improves at\nrelatively low temperatures (800 {\\deg}C). Elastic properties of the boron\nfilms have been determined by Brillouin spectroscopy. Finally, micro-hardness\ntests have been used to explore cohesion and hardness of B films deposited on\naluminum, silicon and alumina. The reported deposition strategy allows the\ngrowth of reliable boron coatings paving the way for their use in many\ntechnology fields.",
        "positive": "Nonequilibrium phonon dynamics beyond the quasiequilibrium approach: The description of nonequilibrium states of solids in a simplified manner is\na challenge in the field of ultrafast dynamics. Here, the phonon thermalization\nin solids through the three-phonon scatterings is investigated by solving the\nBoltzmann transport equation (BTE). The numerical solution of the BTE shows\nthat the transverse acoustic and longitudinal acoustic (LA) phonon temperatures\nare not well-defined during the relaxation, indicating the breakdown of the\nquasiequilibrium approximation. The development of hot and cold phonons and the\nbackward energy flow from low to high energy phonons are observed in the\ninitial and final stage of the relaxation, respectively. A minimal model is\npresented to relate the latter with the power-law decay of the LA phonon\nenergy."
    },
    {
        "anchor": "An analytical model for the mechanical deformation of locally\n  graphitized diamond: We propose an analytical model to describe the mechanical deformation of\nsingle-crystal diamond following the local sub-superficial graphitization\nobtained by laser beams or MeV ion microbeam implantation. In this case, a\nlocal mass-density variation is generated at specific depths within the\nirradiated micrometric regions, which in turn leads to swelling effects and the\ndevelopment of corresponding mechanical stresses. Our model describes the\nconstrained expansion of the locally damaged material and correctly predicts\nthe surface deformation, as verified by comparing analytical results with\nexperimental profilometry data and Finite Element simulations. The model can be\nadopted to easily evaluate the stress and strain fields in locally graphitized\ndiamond in the design of microfabrication processes involving the use of\nfocused ion/laser beams, for example to predict the potential formation of\ncracks, or to evaluate the influence of stress on the properties of opto\nmechanical devices.",
        "positive": "Non-Magnetic Half-Metals: Half-metals are a class of materials that are metallic only for one spin\ndirection, and are essential for spintronics applications where one needs to\nread, write, store and transfer spin-data. This spin sensitivity appears to\nrestrict them to be magnetic, and the known examples indeed are. The\nfabrication of real spintronic devices from such materials is often hampered,\nhowever, by stray magnetic fields, domain walls, short spin coherence times,\nscattering on magnetic atoms or magnetically active interfaces, and other\ncharacteristics that come along with the magnetism. The surfaces of topological\ninsulators, or Dirac or Weyl semimetals, could be an alternative, but\nproduction of high-quality thin films without the presence of the bulk states\nat the Fermi level remains very challenging. Here we introduce non-magnetic\nhalf-metals and demonstrate that this state is realized in IrBiSe. Using\nangle-resolved photoemission spectroscopy and band structure calculations we\nfind a record-high Dresselhaus spin-orbit splitting, fully spin-polarized\nremnant Fermi surfaces and a chiral 3D spin-texture, all with no magnetism\npresent. Promising applications include using IrBiSe as a source of\nspin-polarized electrons, and lightly doped IrBiSe is expected to generate\nelectric-field-controlled spin-polarized currents, free from back scattering,\nand could host triplet superconductivity."
    },
    {
        "anchor": "Unraveling the influence of electronic and magnonic spin current\n  injection near the magnetic ordering transition of IrMn metallic\n  antiferromagnets: Although spin injection at room temperature in an IrMn metallic\nantiferromagnet strongly depends on the transport regime, and is more efficient\nin the case of magnonic transport, in this article, we present experimental\ndata demonstrating that the enhanced efficiency of spin injection caused by\nspin fluctuations near the ordering temperature can be as efficient for the\nelectronic and magnonic transport regimes. By selecting representative\ninteracting environments, we also demonstrated that the amplification of spin\ninjection near the ordering temperature of the IrMn antiferromagnet is\nindependent of exchange coupling with an adjacent NiFe ferromagnet. In\naddition, our findings confirm that the spin current carried by magnons\npenetrates deeper than that transported by conduction electrons in IrMn.\nFinally, our data indicates that the value of the ordering temperature for the\nIrMn antiferromagnet is not significantly affected by either the electronic or\nmagnonic nature of the spin current probe, or by exchange coupling.",
        "positive": "Coexistence of high electrical conductivity and weak ferromagnetism in\n  Cr doped Y$_2$Ir$_2$O$_7$ pyrochlore iridate: We report the structural, magnetic and electrical transport properties of\nY$_2$Ir$_{2-x}$Cr$_x$O$_7$ pyrochlore iridates. The chemical doping leads to\norder of magnitude enhancement of electrical conductivity. The introduction of\nCr3+ at Ir4+ site tends to distort the Ir-O6 octahedra and suppresses\nantiferromagnetic correlation. The X-ray photoemission spectroscopy\nmeasurements suggest the coexistence of Ir4+ and Ir5+ valence states in the\nY$_2$Ir$_{2-x}$Cr$_x$O$_7$ compounds. The concentration of Ir5+ is enhanced\nwith Cr doping, leading to weak ferromagnetism and enhanced electrical\nconductivity. A cluster-glass like transition is also observed at low\ntemperature with Cr doping, possibly due to competing ferromagnetic and\nantiferromagnetic interaction."
    },
    {
        "anchor": "Finding the stable structures of 2D hexagonal materials with Bayesian\n  optimization: Beyond the structural relationship with 3D crystals in\n  weakly-bonded binary systems: The graphene-graphite relationship in structural geometry is a basic\nprinciple to predict novel two-dimensional (2D) materials. Here, we demonstrate\nthat this is not the case in binary metallic systems. We use the Bayesian\noptimization framework combined with the density-functional theory approach to\ndetermine the stable configuration of atomic species on a hexagonal plane. We\nshow that the optimized structure of 2D Cu-Au exhibits the hexagonal lattice of\na hexagonal ring of Cu atoms containing one Au atom, where the number of the Cu\natoms is larger than that of the Au atoms in the unit cell, which is difficult\nto speculate from the atomic distribution of CuAu in the L1$_0$ structure. We\nalso show that 2D Cu-$X$ with $X=$ Be, Zn, and Pd have hexagonal or elongated\nrings containing different atoms in the unit cell. Based on the binary\nLennard-Jones model, we propose that such structures can appear for\nweakly-bonded systems located in between the phase-separated and\nstrongly-bonded systems with the interatomic interaction energy between\ndifferent species.",
        "positive": "Stickiness of randomly rough surfaces with high fractal dimension: is\n  there a fractal limit?: Two surfaces are \"sticky\" if breaking their mutual contact requires a finite\ntensile force. At low fractal dimensions D, there is consensus stickiness does\nnot depend on the upper truncation frequency of roughness spectrum (or\n\"magnification\"). As debate is still open for the case at high D, we exploit\nBAM theory of Ciavarella and Persson-Tosatti theory, to derive criteria for all\nfractal dimensions. For high D, we show that stickiness is more influenced by\nshort wavelength roughness with respect to the low D case. BAM converges at\nhigh magnifications to a simple criterion which depends only on D, in agreement\nwith theories that includes Lennard-Jones traction-gap law, while\nPersson-Tosatti disagrees because of its simplifying approximations."
    },
    {
        "anchor": "Capturing long-range interaction with reciprocal space neural network: Machine Learning (ML) interatomic models and potentials have been widely\nemployed in simulations of materials. Long-range interactions often dominate in\nsome ionic systems whose dynamics behavior is significantly influenced.\nHowever, the long-range effect such as Coulomb and Van der Wales potential is\nnot considered in most ML interatomic potentials. To address this issue, we put\nforward a method that can take long-range effects into account for most ML\nlocal interatomic models with the reciprocal space neural network. The\nstructure information in real space is firstly transformed into reciprocal\nspace and then encoded into a reciprocal space potential or a global descriptor\nwith full atomic interactions. The reciprocal space potential and descriptor\nkeep full invariance of Euclidean symmetry and choice of the cell. Benefiting\nfrom the reciprocal-space information, ML interatomic models can be extended to\ndescribe the long-range potential including not only Coulomb but any other\nlong-range interaction. A model NaCl system considering Coulomb interaction and\nthe GaxNy system with defects are applied to illustrate the advantage of our\napproach. At the same time, our approach helps to improve the prediction\naccuracy of some global properties such as the band gap where the full atomic\ninteraction beyond local atomic environments plays a very important role. In\nsummary, our work has expanded the ability of current ML interatomic models and\npotentials when dealing with the long-range effect, hence paving a new way for\naccurate prediction of global properties and large-scale dynamic simulations of\nsystems with defects.",
        "positive": "Doping effects in single-layered La0.5Sr1.5MnO4 manganites: In this paper we report the results of the synthesis and structural,\ntransport and magnetic characterization of pure La0.5Sr1.5MnO4 (LSMO) and 5%\ndoped samples, i.e. La0.5Sr1.5Mn0.95B0.05O4, where B = Ru, Co and Ni. It is\nshown that even a light doping is successful in suppressing the charge and\norbital ordering found for the pure LSMO. In general, doping favours the\ncarrier motion and, from a magnetic point of view, the set-up a spin-glass\nstate. Moreover, structural parameters show an anisotropy in the lattice\nconstant variation, with the tetragonal distortion increasing as the cell\nvolume reduces, which may suggest a variation in the relative nature of the\norbital character of the eg electrons along with the overall cation size."
    },
    {
        "anchor": "Critical temperature of two-dimensional hydrogenated multilayer\n  graphene-based diluted ferromagnet: In the paper a theoretical study of critical (Curie) temperature of diluted\nferromagnet based on multilayer graphene (or graphite) with hydrogen adatoms\ndeposited over carbon atoms belonging to single sublattice is presented. The\ncalculations are performed within Pair Approximation (PA) for diluted\nferromagnetic system with long-range interactions. The method is able to take\ninto account the spin-space anisotropy of coupling. The results obtained within\nMean Field Approximation (MFA) are also presented for comparison. The assumed\ninteraction between hydrogen adatom spins is inversely proportional to their\nmutual distance, with the additional exponential attenuation reflecting the\npresence of disorder in the system. The results obtained for a wide range of\nimpurity concentrations and interaction decay length are discussed. The\nstrongly non-linear behaviour of critical temperature as a function of dilution\nis predicted, at variance with MFA predictions. Moreover, MFA tends to\noverestimate heavily the critical temperature values compared to PA. An\nuniversal dependence of critical temperature on impurity concentration and\ninteraction decay length is found for strong dilution regime.",
        "positive": "The Nature of Interlayer Binding and Stacking of $sp$-$sp^{2}$\n  Hybridized Carbon Layers: A Quantum Monte Carlo Study: $\\alpha$-graphyne is a two-dimensional sheet of $sp$-$sp^2$ hybridized carbon\natoms in a honeycomb lattice. While the geometrical structure is similar to\nthat of graphene, the hybridized triple bonds give rise to electronic structure\nthat is different from that of graphene. Similar to graphene, $\\alpha$-graphyne\ncan be stacked in bilayers with two stable configurations, but the different\nstackings have very different electronic structures: one is predicted to have\ngapless parabolic bands and the other a tunable band gap which is attractive\nfor applications. In order to realize applications, it is crucial to understand\nwhich stacking is more stable. This is difficult to model, as the stability is\na result of weak interlayer van der Waals interactions which are not well\ncaptured by density functional theory (DFT). We have used quantum Monte Carlo\nsimulations that accurately include van der Waals interactions to calculate the\ninterlayer binding energy of bilayer graphyne and to determine its most stable\nstacking mode. Our results show that interlayer bindings of $sp$- and\n$sp^{2}$-bonded carbon networks are significantly underestimated in a Kohn-Sham\nDFT approach, even with an exchange-correlation potential corrected to include,\nin some approximation, van der Waals interactions. Finally, our quantum Monte\nCarlo calculations reveal that the interlayer binding energy difference between\nthe two stacking modes is only 0.9(4) meV/atom. From this we conclude that the\ntwo stable stacking modes of bilayer $\\alpha$-graphyne are almost degenerate\nwith each other, and both will occur with about the same probability at room\ntemperature unless there is a synthesis path that prefers one stacking over the\nother."
    },
    {
        "anchor": "Unusual negative formation enthalpies and atomic ordering in isovalent\n  alloys of transition metal dichalcogenide monolayers: Common substitutional isovalent semiconductor alloys usually form disordered\nmetastable phases with positive excess formation enthalpies ({\\Delta}H). In\ncontrast, monolayer alloys of transition metal dichalcogenides (TMDs) MX2 (M =\nMo, W; X = S, Se) always have negative {\\Delta}H, suggesting atomic ordering,\nwhich is, however, not yet experimentally observed. Using first-principles\ncalculations, we find that the negative {\\Delta}H of cation-mixed TMD alloys\nresults from the charge transfer from weak Mo-X to nearest strong W-X bonds and\nthe negative {\\Delta}H of anion-mixed TMD alloys comes from the larger energy\ngain due to the charge transfer from Se to nearest S atoms than the energy cost\ndue to the lattice mismatch. Consequently, cation-mixed and anion-mixed alloys\nshould energetically prefer to have Mo-X-W and S-M-Se ordering, respectively.\nThe atomic ordering, however, is only locally ordered but disordered in the\nlong range due to the symmetry of TMD monolayers, as demonstrated by many\nenergetically degenerate structures for given alloy compositions. Besides, the\nlocal ordering and disordering effects on the macroscopic properties such as\nbandgaps and optical absorptions are negligible, making the experimental\nobservation of locally ordered TMD alloys challenging. We propose to take the\nadvantage of microscopic properties such as defects which strongly depend on\nlocal atomic configurations for experiments to identify the disordering and\nlocal ordering in TMD alloys. Finally, quaternary TMD alloys by mixing both\ncations and anions are studied to have a wide range of bandgaps for\noptoelectronic applications. Our work is expected to help the formation and\nutilization of TMD alloys.",
        "positive": "Epitaxy and magnetotransport of Sr_2FeMoO_6 thin films: By pulsed-laser deposition epitaxial thin films of Sr_2FeMoO_6 have been pre-\npared on (100) SrTiO_3 substrates. Already for a deposition temperature of 320\nC epitaxial growth is achieved. Depending on deposition parameters the films\nshow metallic or semiconducting behavior. At high (low) deposition temperature\nthe Fe,Mo sublattice has a rock-salt (random) structure. The metallic samples\nhave a large negative magnetoresistance which peaks at the Curie temperature.\nThe magnetic moment was determined to 4 mu_B per formula unit (f.u.), in\nagreement with the expected value for an ideal ferrimagnetic arrangement. We\nfound an ordinary Hall coefficient of -6.01x10^{-10} m^3/As at 300 K,\ncorresponding to an electronlike charge-carrier density of 1.3 per Fe,Mo-pair.\nIn the semiconducting films the magnetic moment is reduced to 1 mu_B/f.u. due\nto disorder in the Fe,Mo sublattice. In low fields an anomalous holelike\ncontribution dominates the Hall voltage, which vanishes at low temperatures for\nthe metallic films only."
    },
    {
        "anchor": "Uncovering the effects of interface-induced ordering of liquid on\n  crystal growth using machine learning: The process of crystallization is often understood in terms of the\nfundamental microstructural elements of the crystallite being formed, such as\nsurface orientation or the presence of defects. Considerably less is known\nabout the role of the liquid structure on the kinetics of crystal growth. Here\natomistic simulations and machine learning methods are employed together to\ndemonstrate that the liquid adjacent to solid-liquid interfaces presents\nsignificant structural ordering, which effectively reduces the mobility of\natoms and slows down the crystallization kinetics. Through detailed studies of\nsilicon and copper we discover that the extent to which liquid mobility is\naffected by interface-induced ordering (IIO) varies greatly with the degree of\nordering and nature of the adjacent interface. Physical mechanisms behind the\nIIO anisotropy are explained and it is demonstrated that incorporation of this\neffect on a physically-motivated crystal growth model enables the quantitative\nprediction of the growth rate temperature dependence.",
        "positive": "Investigating Phase Transition and Morphology of Bi-Te Thermoelectric\n  System: The optimization of secondary phase in thermoelectric(TE) materials can\n{helps in improvisation of material's efficiency}. Being a potential\n{contender} for lower temperature TE application, bismuth\ntelluride(Bi$_2$Te$_3$) nanoparticles were synthesized via different routes and\nprofiles to optimize their pure single phase. Systematic characterizations were\nperformed with the help of X-ray diffraction (XRD), Rietveld refinement and\nfield effect-scanning electron microscopy(FE-SEM) for structural and\nmorphological behavior, while TE properties such as Seebeck coefficient,\nelectrical conductivity and power-factor were measured for the purest sample\nchosen. Rietveld refinement in the XRD pattern of the samples revealed that\nonly a small amount ($\\sim$ 1.6\\%) of Bi$_2$Te$_3$ was formed in\nco-precipitation method, while the hydrothermal technique increases this phase\nwith increment in synthesis duration. This work focused on the phase evolution\nof Bi$_2$Te$_3$ with increasing synthesis duration time at constant temperature\nand vice-versa. XRD and Rietveld refinement revealed that the hydrothermal\ntechnique (150 $^\\circ$C for 48 hours) can synthesize purest samples (84\\%\nBi$_2$Te$_3$ phase in this case). {FE-SEM and Energy Dispersive X-ray analysis\nunveiled that the impure phases in the system {were} quantitatively reduced,\nand it supported by decline in atomic percentage of oxygen from 37\\% to 11\\%,\nin addition to this, it was also found that particle size was also decreased\nwith increase in temperature.} The observed electrical conductivity of the\nchosen sample is $\\sim$20 times greater, while Seebeck coefficient is $\\sim$3\ntimes lower than that of pure Bi$_2$Te$_3$ phase. The detailed analysis has\ngeneralized the growth mechanism in Bi$_2$Te$_3$ phase evolution by the\ndiffusion of Bi into Te nanorods to fabricate hexagonal Bi$_2$Te$_3$."
    },
    {
        "anchor": "Anisotropic Rheology and Friction of Suspended Graphene: Graphene is a powerful membrane prototype for both applications and\nfundamental research. Rheological phenomena including indentation, twisting,\nand wrinkling in deposited and suspended graphene are actively investigated to\nunravel the mechanical laws at the nanoscale. Most studies focused on isotropic\nset-ups, while realistic graphene membranes are often subject to strongly\nanisotropic constraints, with important consequences for the rheology, strain,\nindentation, and friction in engineering conditions.",
        "positive": "Spin-orbit torques in Co/Pd multilayer nanowires: Current induced spin-orbit torques have been studied in ferromagnetic\nnanowires made of 20 nm thick Co/Pd multilayers with perpendicular magnetic\nanisotropy. Using Hall voltage and lock-in measurements, it is found that upon\ninjection of an electric current both in-plane (Slonczewski-like) and\nperpendicular (field-like) torques build up in the nanowire. The torque\nefficiencies are found to be as large as 1.17 kOe and 5 kOe at 108 A/cm2 for\nthe in-plane and perpendicular components, respectively, which is surprisingly\ncomparable to previous studies in ultrathin (~ 1 nm) magnetic bilayers. We show\nthat this result cannot be explained solely by spin Hall effect induced torque\nat the outer interfaces, indicating a probable contribution of the bulk of the\nCo/Pd multilayer."
    },
    {
        "anchor": "Accurate prediction of Hall mobilities in two-dimensional materials\n  through gauge-covariant quadrupolar contributions: Despite considerable efforts, accurate computations of electron-phonon and\ncarrier transport properties of low-dimensional materials from first principles\nhave remained elusive. By building on recent advances in the description of\nlong-range electrostatics, we develop a general approach to the calculation of\nelectron-phonon couplings in two-dimensional materials. We show that the\nnonanalytic behavior of the electron-phonon matrix elements depends on the\nWannier gauge, but that a missing Berry connection restores invariance to\nquadrupolar order. We showcase these contributions in a MoS$_2$ monolayer,\ncalculating intrinsic drift and Hall mobilities with precise Wannier\ninterpolations. We also find that the contributions of dynamical quadrupoles to\nthe scattering potential are essential, and that their neglect leads to errors\nof 23% and 76% in the room temperature electron and hole Hall mobilities,\nrespectively.",
        "positive": "Deviation From the Landau-Lifshitz-Gilbert equation in the Inertial\n  regime of the Magnetization: We investigate in details the inertial dynamics of a uniform magnetization in\nthe ferromagnetic resonance (FMR) context. Analytical predictions and numerical\nsimulations of the complete equations within the Inertial\nLandau-Lifshitz-Gilbert (ILLG) model are presented. In addition to the usual\nprecession resonance, the inertial model gives a second resonance peak\nassociated to the nutation dynamics provided that the damping is not too large.\nThe analytical resolution of the equations of motion yields both the precession\nand nutation angular frequencies. They are function of the inertial dynamics\ncharacteristic time $\\tau$, the dimensionless damping $\\alpha$ and the static\nmagnetic field $H$. A scaling function with respect to $\\alpha\\tau\\gamma H$ is\nfound for the nutation angular frequency, also valid for the precession angular\nfrequency when $\\alpha\\tau\\gamma H\\gg 1$. Beyond the direct measurement of the\nnutation resonance peak, we show that the inertial dynamics of the\nmagnetization has measurable effects on both the width and the angular\nfrequency of the precession resonance peak when varying the applied static\nfield. These predictions could be used to experimentally identify the inertial\ndynamics of the magnetization proposed in the ILLG model."
    },
    {
        "anchor": "Impact of the skyrmion spin texture on magnetoresistance: We investigate the impact of the local spin texture on the differential\nconductance by scanning tunneling microscopy. In the focus is the previously\nfound non-collinear magnetoresistance, which originates from spin mixing\neffects upon electron hopping between adjacent sites with canted magnetic\nmoments. In the present work it is studied with lateral resolution both for the\nzero magnetic field spin spiral state as well as for individual magnetic\nskyrmions at different magnetic field values. We analyze in detail the response\nof the differential conductance and find different dependencies of peak energy\nand peak intensity on the local properties of the non-collinear spin texture.\nWe find that in the center of a skyrmion the peak energy and intensity scale\nroughly linear with the angle between nearest neighbor moments. Elsewhere in\nthe skyrmion, where the non-collinearity is not isotropic and the magnetization\nquantization axis varies, the behavior of the peak energy is more complex.",
        "positive": "Spin-dependent optical excitations in LiFeO2: The three-dimensional ternary LiFeO2 compound presents various unusual\nessential properties. The main features are thoroughly explored by the density\nfunctional and many-body perturbation theory. The concise physical/chemical\npicture, the critical spin-polarizations and orbital hybridizations in the Li-O\nand Fe-O bonds, are clearly examined through geometric optimization,\nquasi-particle energy spectra, spin-polarized density of states, the spatial\ncharge densities, the spin-density distributions, and the strong optical\nresponses. The unusual optical transitions cover various frequency-dependent\nabsorption structures, and the most prominent plasmon modes are identified by\nthe dielectric functions, energy loss functions, reflectance spectra, and\nabsorption coefficients. Optical excitations are anisotropic and strongly\naffected by excitonic effects. The close combinations of electronic, magnetic\nand optical properties allow us to identify the significant spin-polarizations\nand orbital hybridizations for each available excitation channel. The lithium\nferrite compound can be used for spintronic and photo-catalysis applications."
    },
    {
        "anchor": "Effect of magnetic state on the $\u03b3-\u03b1$ transition in iron:\n  First-principle calculations of the Bain transformation path: Energetics of the fcc ($\\gamma$) - bcc ($\\alpha$) lattice transformation by\nthe Bain tetragonal deformation is calculated for both magnetically ordered and\nparamagnetic (disordered local moment) states of iron. The first-principle\ncomputational results manifest a relevance of the magnetic order in a scenario\nof the $\\gamma$ - $\\alpha$ transition and reveal a special role of the Curie\ntemperature of $\\alpha$-Fe, $T_C$, where a character of the transformation is\nchanged. At a cooling down to the temperatures $T < T_C$ one can expect that\nthe transformation is developed as a lattice instability whereas for $T > T_C$\nit follows a standard mechanism of creation and growth of an embryo of the new\nphase. It explains a closeness of $T_C$ to the temperature of start of the\nmartensitic transformation, $M_s$.",
        "positive": "NMR study of Ni50+xTi50-x Strain-Glass: We studied Ni50+xTi50-x with compositions up to x = 2, performing 47Ti and\n49Ti nuclear magnetic resonance (NMR) measurements from 4 K to 400 K. For large\nx in this system, a strain-glass appears in which frozen ferroelastic\nnano-domains replace the displacive martensite structural transition. Here we\ndemonstrate that NMR can provide an extremely effective probe of the strain\nglass freezing process, with large changes in NMR line-shape due to the effects\nof random strains which become motionally narrowed at high temperatures. At the\nsame time with high-resolution x-ray diffraction we confirm the lack of\nstructural changes in x >= 1.2 samples, while we show that there is little\nchange in the electronic behavior across the strain glass freezing temperature.\nNMR spin-lattice relaxation time (T1) measurements provide a further measure of\nthe dynamics of the freezing process, and indicate a predominantly thermally\nactivated behavior both above and below the strain-glass freezing temperature.\nWe show that the strain glass results are consistent with a very small density\nof critically divergent domains undergoing a Vogel-Fulcher-type freezing\nprocess, coexisting with domains exhibiting faster dynamics and stronger\npinning."
    },
    {
        "anchor": "The solid-state Li-ion conductor Li$_7$TaO$_6$: A combined computational\n  and experimental study: We study the oxo-hexametallate Li$_7$TaO$_6$ with first-principles and\nclassical molecular dynamics simulations, obtaining a low activation barrier\nfor diffusion of $\\sim$0.29 eV and a high ionic conductivity of $5.7 \\times\n10^{-4}$ S cm$^{-1}$ at room temperature (300 K). We find evidence for a wide\nelectrochemical stability window from both calculations and experiments,\nsuggesting its viable use as a solid-state electrolyte in next-generation\nsolid-state Li-ion batteries. To assess its applicability in an electrochemical\nenergy storage system, we performed electrochemical impedance spectroscopy\nmeasurements on multicrystalline pellets, finding substantial ionic\nconductivity, if below the values predicted from simulation. We further\nelucidate the relationship between synthesis conditions and the observed ionic\nconductivity using X-ray diffraction, inductively coupled plasma optical\nemission spectrometry, and X-ray photoelectron spectroscopy, and study the\neffects of Zr and Mo doping.",
        "positive": "Novel one-pot sol-gel synthesis route of Fe3C/few-layered graphene\n  core/shell nanoparticles embedded in a carbon matrix: Fe3C/few-layered graphene core/shell nanoparticles embedded in a carbon\nmatrix are synthesized by a novel two-step surfactant sol-gel strategy, where\nthe processes of hydrolysis, polycondensation and drying take place in a\none-pot. The present approach is based on the combined action of oleic acid and\noleylamine, which act sterically on the precursor micelles when a densification\ntemperature is performed in a reducing atmosphere. The structural and magnetic\nevolution of the formed compounds is investigated, ranging from iron oxides\nsuch as Fe3O4 and FeO, to the formation of pure Fe3C/C samples from 700 {\\deg}C\nonwards. Interestingly, Fe3C nanoparticles with a size of ~20 nm crystallize\nimmersed in the carbon matrix and the surrounding environment forms an oriented\nencapsulation built by few-layered graphene. The nanostructures show a\nsaturation magnetization of ~43 emu/g and a moderate coercivity of ~500 Oe.\nThereby, an innovative chemical route to produce single phase Fe3C\nnanoparticles is described, and an effective method of few-layered graphene\npassivation is proposed, yielding a product with a high magnetic response and\nhigh chemical stability against environmental corrosion."
    },
    {
        "anchor": "Modelling of interacting dimer adsorption: Adsorption of dimers is modelled using random sequential adsorption\nalgorithm. The interaction between molecules is given by screened electrostatic\npotential. The paper focuses on the properties of adsorbed monolayers as well\nas the dependence of adsorption kinetics on interaction range. We designate\nrandom maximal coverage ratios, density autocorrelations and orientational\nordering inside layers. Moreover the detailed analysis of adsorption kinetics\nis presented including a discussion of Feder's law validity and new numerical\nmethod for modelling diffusion driven adsorption. Results of numerical\nsimulations are compared with experimental data obtained previously for insulin\ndimers.",
        "positive": "Review of Spin Orbit Coupled Semimetal SrIrO3 in thin film form: Spin orbit coupling provides a mechanism to lock the momentum of electron to\nits spin degree, recent years was revealed to be essential in arousing many\nnovel physical behaviors. SrIrO3 is a typical metallic member of the strong\nspin orbit coupling iridate family. Its orthorhombic phase was confirmed as a\nparticular spin orbit coupling assistant electron correlated semimetal with\nsmall electron and hole pockets, and was supposed to host versatile topological\nphases, with prospect of opening a new topological matter field based on\noxides. The existing experiments have demonstrated that orthorhombic SrIrO3 can\nbe easily synthesized at two dimensional scale films under the substrate\nlattice constraint, and the films display Fermi-liquid behavior in high\ntemperature and generally two dimensional weak localization resulted metal\ninsulator transition. The properties of orthorhombic SrIrO3 film are sensitive\nto the rotation and tilting angle, as well as the interlayer coupling of the\nIrO6 octahedras, consequently can be tuned through substrate strain engineering\nand size scale. For example, the film was approached a state similar to Sr2IrO4\nat the ultrathin limit to several unit cell, becoming a canted\nantiferromagnetic semiconductor/insulator. The existing knowledges suggest\nurgent demands of researches on the superlattices constructed with orthorhombic\nSrIrO3, for further understanding the evolution mechanism of the electron\nstructure, and so the relevant magnetic state and topological phases in the\northorhombic SrIrO3 and its family."
    },
    {
        "anchor": "Understanding the Initial Stages of Reversible Mg Deposition and\n  Stripping in Inorganic Non-Aqueous Electrolytes: Multi-valent (MV) battery architectures based on pairing a Mg metal anode\nwith a high-voltage ($\\sim$ 3 V) intercalation cathode offer a realistic design\npathway toward significantly surpassing the energy storage performance of\ntraditional Li-ion based batteries, but there are currently only few\nelectrolyte systems that support reversible Mg deposition. Using both static\nfirst-principles calculations and $ab\\; initio$ molecular dynamics, we perform\na comprehensive adsorption study of several salt and solvent species at the\ninterface of Mg metal with an electrolyte of Mg$^{2+}$ and Cl$^-$ dissolved in\nliquid tetrahydrofuran (THF). Our findings not only provide a picture of the\nstable species at the interface, but also explain how this system can support\nreversible Mg deposition and as such we provide insights in how to design other\nelectrolytes for Mg plating and stripping. The active depositing species are\nidentified to be (MgCl)$^+$ monomers coordinated by THF, which exhibit\npreferential adsorption on Mg compared to possible passivating species (such as\nTHF solvent or neutral MgCl$_2$ complexes). Upon deposition, the energy to\ndesolvate these adsorbed complexes and facilitate charge-transfer is shown to\nbe small ($\\sim$ 61 $-$ 46.2 kJ mol$^{-1}$ to remove 3 THF from the strongest\nadsorbing complex), and the stable orientations of the adsorbed but desolvated\n(MgCl)$^+$ complexes appear favorable for charge-transfer. Finally,\nobservations of Mg-Cl dissociation at the Mg surface at very low THF\ncoordinations (0 and 1) suggest that deleterious Cl incorporation in the anode\nmay occur upon plating. In the stripping process, this is beneficial by further\nfacilitating the Mg removal reaction.",
        "positive": "Coherence/incoherence transition temperature in molecular spin: We examine the coherence/incoherence transition temperature of a generic\nmolecular spin. Our results demonstrates that a molecular spin with a high\ncoherence/incoherence transition temperature should possess a low spin number\nand low axiality, or high spin number and high axiality. Interestingly, the\nlatter is better protected from the magnetic noises than the former and thus be\nthe best candidate for a robust electron-based molecular spin qubit/qudit. The\ntransition temperature can be further optimized if a large non-axial component\nof the spin Hamiltonian exists."
    },
    {
        "anchor": "Evidence for quasi-one-dimensional charge density wave in CuTe by\n  angle-resolved photoemission spectroscopy: We report the electronic structure of CuTe with a high charge density wave\n(CDW) transition temperature Tc = 335 K by angle-resolved photoemission\nspectroscopy (ARPES). An anisotropic charge density wave gap with a maximum\nvalue of 190 meV is observed in the quasi-one-dimensional band formed by Te px\norbitals. The CDW gap can be filled by increasing temperature or electron\ndoping through in situ potassium deposition. Combining the experimental results\nwith calculated electron scattering susceptibility and phonon dispersion, we\nsuggest that both Fermi surface nesting and electron-phonon coupling play\nimportant roles in the emergence of the CDW.",
        "positive": "Concentration-control in all-solution processed semiconducting polymer\n  doping and high conductivity performances: Simultaneously optimizing performances, processability and fabrication cost\nof organic electronic materials is the continual source of compromise hindering\nthe development of disruptive applications. In this work, we identified a\nstrategy to achieve record conductivity values of one of the most benchmarked\nsemiconducting polymers by doping with an entirely solution-processed,\nwater-free and cost-effective technique. High electrical conductivity for\npoly(3-hexylthiophene) up to 21 S/cm has been achieved, using a commercially\navailable electron acceptor as both a Lewis acid and an oxidizing agent. While\nwe managed water-free solution-processing a three-time higher conductivity for\nP3HT with a very affordable/available chemical, near-field microscopy reveals\nthe existence of concentration-dependent higher-conductivity micro-domains for\nwhich furthermore process optimization might access to even higher\nperformances. In the perpetual quest of reaching higher performances for\norganic electronics, this work shall greatly unlock applications maturation\nrequiring higher-scale processability and lower fabrication costs concomitant\nof higher performances and new functionalities, in the current context where\nunderstanding the doping mechanism of such class of materials remains of the\ngreatest interest."
    },
    {
        "anchor": "Nature and strength of bonding in a crystal of semiconducting nanotubes:\n  van der Waals density functional calculations and analytical results: The dispersive interaction between nanotubes is investigated through ab\ninitio theory calculations and in an analytical approximation. A van der Waals\ndensity functional (vdW-DF) [Phys. Rev. Lett. 92, 246401 (2004)] is used to\ndetermine and compare the binding of a pair of nanotubes as well as in a\nnanotube crystal. To analyze the interaction and determine the importance of\nmorphology, we furthermore compare results of our ab initio calculations with a\nsimple analytical result that we obtain for a pair of well-separated nanotubes.\nIn contrast to traditional density functional theory calculations, the vdW-DF\nstudy predicts an intertube vdW bonding with a strength that is consistent with\nrecent observations for the interlayer binding in graphitics. It also produce a\nnanotube wall-to-wall separation which is in very good agreement with\nexperiments. Moreover, we find that the vdW-DF result for the nanotube-crystal\nbinding energy can be approximated by a sum of nanotube-pair interactions when\nthese are calculated in vdW-DF. This observation suggests a framework for an\nefficient implementation of quantum-physical modeling of the CNT bundling in\nmore general nanotube bundles, including nanotube yarn and rope structures.",
        "positive": "Hot-electron noise suppression in n-Si via the Hall effect: We investigate how hot-electron fluctuations in n-type Si are affected by the\npresence of an intense (static) magnetic field in a Hall geometry. By using the\nMonte Carlo method, we find that the known Hall-effect-induced redistribution\nof electrons among valleys can suppress electron fluctuations with a\nsimultaneous enhancement of the drift velocity."
    },
    {
        "anchor": "Electrolytes for Li-ion all-solid-state batteries: a first-principles\n  comparative study of Li10GeP2O12 and Li10GeP2S12 in the LISICON and LGPS\n  phases: In this work we address Li-ion diffusion in thio-LISICON materials and in\ntheir oxide counterparts, exploring both the orthorhombic and tetragonal phases\nof Li10GeP2S12(LGPS) and Li10GeP2O12(LGPO) through extended Car-Parrinello\nmolecular dynamics in the canonical and isobaric-isothermal ensemble. The\n(quasi-)orthorhombic and tetragonal phases are studied both for the oxide and\nfor the sulfide, with the aim of comparing their conductivity with the same\napproach; out of these four case studies, tetragonal LGPO has not been reported\nand, while dynamically stable, it sits (0.04 Ha/formula unit) above\northorhombic LGPO. We calculate activation energies for diffusion of 0.18 eV\nand 0.23 eV for tetragonal and orthorhombic LGPS, and of 0.22 eV and 0.34eV for\ntetragonal and orthorhombic LGPO. In line with experiments, we find\northorhombic LGPO orders of magnitude less conductive, at room temperature,\nthan the two sulfide systems. However, this is not the case for tetragonal\nLGPO, which, although less stable than its orthorhombic allotrope, shows at\nroom temperature a conductivity comparable to orthorhombic and tetragonal LGPS,\nand, if synthesized, could make a very attractive Li-ion conductor.",
        "positive": "Influence of rhombohedral stacking order in the electrical resistance of\n  bulk and mesoscopic graphite: The electrical, in-plane resistance as a function of temperature $R(T)$ of\nbulk and mesoscopic thin graphite flakes obtained from the same batch was\ninvestigated. Samples thicker than $\\sim 30$ nm show metalliclike contribution\nin a temperature range that increases with the sample thickness, whereas a\nsemiconductinglike behavior was observed for thinner samples. The temperature\ndependence of the in-plane resistance of all measured samples and several\nothers from literature can be very well explained between 2 K and 1100 K\nassuming three contributions in parallel: a metalliclike conducting path at the\ninterfaces between crystalline regions, composed of two semiconducting phases,\ni.e. Bernal and rhombohedral stacking. From the fits of $R(T)$ we obtain a\nsemiconducting energy gap of $110 \\pm 20$meV for the rhombohedral and $38\\pm 8\n$meV for the Bernal phase. The presence of these crystalline phases was\nconfirmed by x-ray diffraction measurements. We review similar experimental\ndata from literature of the last 33 years and two more theoretical models used\nto fit $R(T)$."
    },
    {
        "anchor": "Atomistic, microstructural and micromagnetic aspects of the multiscale\n  modelling of hysteretic phenomena: We formulated a technique which combines the first-principles, micromagnetic\nand microstructural calculations and allows us to study the nature of\nhysteretic phenomena in hard magnets. Two distinct sources of coercivity in\npolytwinned CoPt type magnets, domain wall pinning at antiphase boundaries and\nsplitting at twin boundaries, are illustrated for a realistic microstructure.\nMethodology of multiscale modelling of hysteretic phenomena in nanoscale\nmagnets is discussed.",
        "positive": "Control of Plasmons in Doped Topological Insulators via Basis Atoms: Collective excitations in topologically non-trivial systems have attracted\nconsiderable attention in recent years. Here we study plasmons in the\nSu-Schrieffer-Heeger model whose low-energy electronic band is only partially\nfilled, such that the system is metallic. Using the random phase approximation,\nwe calculate the intra- and inter-band polarization functions and determine the\nbulk plasmonic dispersion from the dielectric function within the random phase\napproximation. We find that the sub-lattice basis states strongly affect the\npolarization functions and therefore control the system's plasmonic\nexcitations. By varying the real-space separation of these local orbitals, one\ncan thus selectively enhance or suppress the plasmonic energies via a tunable\ntrade-off between intra-band and inter-band screening processes. Specifically,\nthis mechanism can be used to stabilize undamped high energy plasmons that have\nalready been reported in related models. We propose scenarios on how to control\nand observe these effects in experiments."
    },
    {
        "anchor": "Geometry-induced spin-filtering in photoemission maps from WTe$_2$\n  surface states: We demonstrate that an important quantum material WTe$_2$ exhibits a new type\nof geometry-induced spin-filtering effect in photoemission, stemming from low\nsymmetry that is responsible for its exotic transport properties. Through the\nlaser-driven spin-polarized angle-resolved photoemission Fermi surface mapping,\nwe showcase highly asymmetric spin textures of electrons photoemitted from the\nsurface states of WTe$_2$. Such asymmetries are not present in the initial\nstate spin textures, which are bound by the time-reversal and crystal lattice\nmirror plane symmetries. The findings are reproduced qualitatively by\ntheoretical modeling within the one-step model photoemission formalism. The\neffect could be understood within the free-electron final state model as an\ninterference due to emission from different atomic sites. The observed effect\nis a manifestation of time-reversal symmetry breaking of the initial state in\nthe photoemission process, and as such it cannot be eliminated, but only its\nmagnitude influenced, by special experimental geometries.",
        "positive": "A three-dimensional atomistic kinetic Monte Carlo study of dynamic\n  solute-interface interaction: A three-dimensional atomistic Kinetic Monte Carlo model was developed and\nused to study the interaction between mobile solutes and a migrating interface.\nWhile the model was developed with a simplified energetic and topological\ndescription, it was also constructed to capture, in the absence of solute, the\nBurke-Turnbull model for interface migration and, in the presence of solutes,\nsolute segregation to different types of interface sites. After parameterizing\nthe model, simulations were performed to study the relationship between average\ninterface velocity and imposed driving pressure for varying solute\nconcentration and solute diffusivity. While the effect of solute concentration\non solute drag pressure was found to be consistent with classical solute drag\nmodels, the effect of solute diffusivity was found to give a response not\ncaptured by either continuum or previously reported two-dimensional atomistic\nmodels. The dependence of maximum drag pressure on solute diffusivity was\nobserved and attributed to the coupling between the structure of a migrating\ninterface and the ability for solute to remain segregated to the interface."
    },
    {
        "anchor": "Structural characterization of SiO2-Na2O-CaO-B2O3-MoO3 glasses: Nuclear spent fuel reprocessing generates high level radioactive waste with\nhigh Mo concentration that are currently immobilized in borosilicate glass\nmatrices containing both alkali and alkaline-earth elements [1]. Because of its\nhigh field strength, Mo6+ ion has a limited solubility in silicate and\nborosilicate glasses and crystallization of alkali or alkaline-earth molybdates\ncan be observed during melt cooling or heat treatment of glasses [2-4]. Glass\ncomposition changes can significantly modify the nature and the relative\nproportions of molybdate crystals that may form during natural cooling of the\nmelt. For instance, in a previous work we showed that CaMoO4 crystallization\ntendency increased at the expenses of Na2MoO4 when B2O3 concentration increased\nin a SiO2-Na2O-CaO-MoO3 glass composition [4]. In this study, we present\nstructural results on two series (Mx, By) of quenched glass samples belonging\nto this system using 29Si, 11B, 23Na MAS NMR and Raman spectroscopies. The\neffect of MoO3 on the glassy network structure is studied and its structural\nrole is discussed (Mx series). The evolution of the distribution of Na+ ions\nwithin the borosilicate network is followed when B2O3 concentration increased\n(By series) and is discussed according to the evolution of the crystallization\ntendency of the melt. For all glasses, ESR was used to investigate the nature\nand the concentration of paramagnetic species.",
        "positive": "Nature and distribution of iron sites in a sodium silicate glass\n  investigated by neutron diffraction and EPSR simulation: The short and medium range structure of a NaFeSi2O6 (NFS) glass has been\ninvestigated by high-resolution neutron diffraction with Fe isotopic\nsubstitution, combined with Empirical Potential Structure Refinement (EPSR)\nsimulations. The majority (~60%) of Fe is 4-coordinated ([4]Fe) and corresponds\nonly to ferric iron, Fe3+, with a distance d[4]Fe3+-O=1.87$\\pm$0.01{\\AA} . This\nis at variance with the 3D-structure predicted by glass stoichiometry. The\nexistence of a majority of [4]Fe3+ sites illustrates a glass structure that\ndiffers from the structure of crystalline NaFeSi2O6, which contains only\noctahedral Fe3+. The EPSR modeling of glass structure shows that [4]Fe3+ is\nrandomly distributed in the silicate network and shares corner with silicate\ntetrahedra. The existence of a majority of [4]Fe3+ sites differs from the\nstructure of the corresponding crystalline phase, which contains only\noctahedral Fe3+. The network-forming behavior of [4]Fe3+, coupled with the\npresence of Na+ ions acting as charge-compensators, is at the origin of\npeculiar physical properties of Fe-bearing glasses, such as the increase of the\nelastic modulus of sodium silicate glasses with increasing Fe-concentration.\nOur data provide also direct evidence for 5-coordinated Fe, with an average\ndistance d[5]Fe-O=2.01$\\pm$0.01{\\AA}. This second Fe population concerns both\nFe2+ and Fe3+. 5-coordinated Fe atoms tend to segregate by sharing mainly\nedges. The direct structural evidence of the dual role of ferric iron in NFS\nglass provides support for understanding the peculiar properties of NFS glass,\nsuch as magnetic, optical, electronic or thermodynamic properties."
    },
    {
        "anchor": "Parametric instability of a magnetic junction under modulated\n  spin-polarized current: The stability is analyzed of the magnetic junction collinear configurations\nagainst small fluctuations under amplitude-modulated current with CPP mode.\nHigh spin injection is assumed. Under parametric resonance conditions, with the\nmodulation frequency twice the precession frequency, instability is possible of\none, or another, or both the collinear configurations. When the dc component of\nthe current density exceeds the instability threshold of the antiparallel\nconfiguration, the parametric instability is suppressed by nonparametric one\nwhich is induced by the dc current. The parametric instability manifests itself\nas lowering the threshold of the dc current density in presence of the\nhigh-frequency current, such an effect has been observed in experiments\nrepeatedly.",
        "positive": "Photo-induced charge state dynamics of the neutral and negatively\n  charged silicon vacancy centers in room-temperature diamond: The silicon vacancy (SiV) center in diamond is drawing much attention due to\nits optical and spin properties, attractive for quantum information processing\nand sensing. Comparatively little is known, however, about the dynamics\ngoverning SiV charge state interconversion mainly due to challenges associated\nwith generating, stabilizing, and characterizing all possible charge states,\nparticularly at room temperature. Here, we use multi-color confocal microscopy\nand density functional theory to examine photo-induced SiV recombination - from\nneutral, to single-, to double-negatively charged - over a broad spectral\nwindow in chemical-vapor-deposition diamond under ambient conditions. For the\nSiV0 to SiV- transition, we find a linear growth of the photo-recombination\nrate with laser power at all observed wavelengths, a hallmark of single photon\ndynamics. Laser excitation of SiV-, on the other hand, yields only fractional\nrecombination into SiV2-, a finding we interpret in terms of a photo-activated\nelectron tunneling process from proximal nitrogen atoms."
    },
    {
        "anchor": "Hard ferromagnetism down to the thinnest limit of iron-intercalated\n  tantalum disulfide: Two-dimensional (2D) magnetic crystals hold promise for miniaturized and\nultralow power electronic devices that exploit spin manipulation. In these\nmaterials, large, controllable magnetocrystalline anisotropy is a prerequisite\nfor the stabilization and manipulation of long-range magnetic order. In known\n2D magnetic crystals, relatively weak magnetocrystalline anisotropy results in\ntypically soft ferromagnetism. Here, we demonstrate that ferromagnetic order\npersists down to the thinnest limit of Fe$_x$TaS$_2$ (Fe-intercalated bilayer\n2H-TaS$_2$) with giant coercivities up to 3 tesla. We prepare Fe-intercalated\nTaS$_2$ by chemical intercalation of van der Waals layered 2H-TaS$_2$ crystals\nand perform variable-temperature quantum transport, transmission electron\nmicroscopy, and confocal Raman spectroscopy measurements to shed new light on\nthe coupled effects of dimensionality, degree of intercalation, and intercalant\norder/disorder on the hard ferromagnetic behavior of Fe$_x$TaS$_2$. More\ngenerally, we show that chemical intercalation gives access to a rich synthetic\nparameter space for low-dimensional magnets, in which magnetic properties can\nbe tailored by the choice of the host material and intercalant identity/amount,\nin addition to the manifold distinctive degrees of freedom available in\natomically thin, van der Waals crystals.",
        "positive": "Extended homologous series of Sn-O layered systems: a first-principles\n  study: Apart from the most studied tin-oxide compounds, SnO and SnO2, intermediate\nstates have been claimed to exist for more than a hundred years. In addition to\nthe known homologous series (Seko et al., Phys. Rev. Lett. 100, 045702 (2008)),\nwe here predict the existence of several new compounds with an O concentration\nbetween 50 % (SnO) and 67 % (SnO2). All these intermediate compounds are\nconstructed from removing one or more (101) oxygen layers of SnO2. Since the\nvan der Waals (vdW) interaction is known to be important for the Sn-Sn\ninterlayer distances, we use a vdW-corrected functional, and compare these\nresults with results obtained with PBE and hybrid functionals. We present the\nelectronic properties of the intermediate structures and we observe a decrease\nof the band gap when (i) the O concentration increases and (ii) more SnO-like\nunits are present for a given concentration. The contribution of the different\natoms to the valence and conduction band is also investigated."
    },
    {
        "anchor": "Theory of the thickness dependence of the charge density wave transition\n  in 1T-TiTe$_2$: Most metallic transition metal dichalcogenides undergo charge density wave\n(CDW) instabilities with similar or identical ordering vectors in bulk and in\nsingle layer, albeit with different critical temperatures. Metallic 1T-TiTe$_2$\nis a remarkable exception as it shows no evidence of charge density wave\nformation in bulk, but it displays a stable $2\\times2$ reconstruction in\nsingle-layer form. The mechanism for this 3D-2D crossover of the transition is\nstill unclear, although strain from the substrate and the exchange interaction\nhave been pointed out as possible formation mechanisms. Here, by performing\nnon-perturbative anharmonic calculations with gradient corrected and hybrid\nfunctionals, we explain the thickness behaviour of the transition in\n1T-TiTe$_2$. We demonstrate that the occurrence of the CDW in single-layer\nTiTe$_2$ occurs from the interplay of non-perturbative anharmonicity and an\nexchange enhancement of the electron-phonon interaction, larger in the single\nlayer than in the bulk. Finally, we study the electronic and structural\nproperties of the single-layer CDW phase and provide a complete description of\nits electronic structure, phonon dispersion as well as infrared and Raman\nactive phonon modes.",
        "positive": "Ferroelectric PbTiO$_{3}$/SrRuO$_{3}$ superlattices with broken\n  inversion symmetry: We have fabricated PbTiO$_{3}$/SrRuO$_{3}$ superlattices with ultra-thin\nSrRuO$_{3}$ layers. Due to the superlattice geometry, the samples show a large\nanisotropy in their electrical resistivity, which can be controlled by changing\nthe thickness of the PbTiO$_{3}$ layers. Therefore, along the ferroelectric\ndirection, SrRuO$_{3}$ layers can act as dielectric, rather than metallic,\nelements. We show that, by reducing the concentration of PbTiO$_{3}$, an\nincreasingly important effect of polarization asymmetry due to compositional\ninversion symmetry breaking occurs. The results are significant as they\nrepresent a new class of ferroelectric superlattices, with a rich and complex\nphase diagram. By expanding our set of materials we are able to introduce new\nbehaviors that can only occur when one of the materials is not a perovskite\ntitanate. Here, compositional inversion symmetry breaking in bi-color\nsuperlattices, due to the combined variation of A and B site ions within the\nsuperlattice, is demonstrated using a combination of experimental measurements\nand first principles density functional theory."
    },
    {
        "anchor": "Selective growth of perovskite oxides on SrTiO3 (001) by control of\n  surface reconstructions: We report surface reconstruction (RC)-dependent growths of SrTiO3 and SrVO3\non a SrTiO3 (001) surface with two different coexisting surface RCs, namely\n(2x1) and c(6x2). Up to the coverage of several layers, epitaxial growth was\nforbidden on the c(6x2) RC under the growth conditions that permitted\nlayer-by-layer epitaxial growth on the (2x1) RC. Scanning tunneling microscopy\nexamination of the lattice structure of the c(6x2) RC revealed that this\nRC-selective growth mainly originated from the significant\nstructural/stoichiometric dissimilarity between the c(6x2) RC and the cubic\nperovskite films. As a result, the formation of SrTiO3 islands was forbidden\nfrom the nucleation stage.",
        "positive": "Electronic measurement and control of spin transport in Silicon: The electron spin lifetime and diffusion length are transport parameters that\ndefine the scale of coherence in spintronic devices and circuits. Since these\nparameters are many orders of magnitude larger in semiconductors than in\nmetals, semiconductors could be the most suitable for spintronics. Thus far,\nspin transport has only been measured in direct-bandgap semiconductors or in\ncombination with magnetic semiconductors, excluding a wide range of\nnon-magnetic semiconductors with indirect bandgaps. Most notable in this group\nis silicon (Si), which (in addition to its market entrenchment in electronics)\nhas long been predicted a superior semiconductor for spintronics with enhanced\nlifetime and diffusion length due to low spin-orbit scattering and lattice\ninversion symmetry. Despite its exciting promise, a demonstration of coherent\nspin transport in Si has remained elusive, because most experiments focused on\nmagnetoresistive devices; these methods fail because of universal impedance\nmismatch obstacles, and are obscured by Lorentz magnetoresistance and Hall\neffects. Here we demonstrate conduction band spin transport across 10 microns\nundoped Si, by using spin-dependent ballistic hot-electron filtering through\nferromagnetic thin films for both spin-injection and detection. Not based on\nmagnetoresistance, the hot electron spin-injection and detection avoids\nimpedance mismatch issues and prevents interference from parasitic effects. The\nclean collector current thus shows independent magnetic and electrical control\nof spin precession and confirms spin coherent drift in the conduction band of\nsilicon."
    },
    {
        "anchor": "Effect of hydrogen gas on magnetic properties of alloys of ferromagnetic\n  metals with Pd and its application in hydrogen gas sensing: The mass-production of fuel-cell vehicles and the eventual transition to the\nhydrogen economy will require safe, inexpensive and reliable sensors capable of\nsimultaneously detecting low concentrations of leaking hydrogen and measuring\nbroad ranges of hydrogen concentration in storage and energy generating\nsystems. Although several competing sensor technologies can potentially be used\nin this role, just a few of them have thus far demonstrated a combination of\nall desirable characteristics. This group of devices also includes\nmagneto-electronic sensors that can detect the presence of hydrogen gas in a\nrange of hydrogen concentrations from zero to 100% at atmospheric pressure with\nthe response time approaching the industry standard of one second. The hydrogen\ngas sensing mechanism underpinning the operation of magneto-electronic sensors\nis based on the physical processes of ferromagnetic resonance, magneto-optical\nKerr effect and anomalous Hall effect that enable one to measure\nhydrogen-induced changes in the magnetic properties of structures combining Pd\nwith one or several ferromagnetic metals such as Co, Fe or Ni. In this chapter,\nwe overview the physical foundations of emergent ferromagnetic Pd-alloy-based\nmagneto-electronic hydrogen sensors and compare their characteristics with\nthose of high-performing multilayer thin film-based counterparts that have\nalready demonstrated a potential to find commercial applications.",
        "positive": "Disruption of Thermally-Stable Nanoscale Grain Structures by Strain\n  Localization: Nanocrystalline metals with average grain sizes of only a few nanometers have\nrecently been observed to fail through the formation of shear bands. Here, we\ninvestigate this phenomenon in nanocrystalline Ni which has had its grain\nstructure stabilized by doping with W, with a specific focus on understanding\nhow strain localization drives evolution of the nanoscale grain structure.\nShear banding was initiated with both microcompression and nanoindentation\nexperiments, followed by site-specific transmission electron microscopy to\ncharacterize the microstructure. Grain growth and texture formation were\nobserved inside the shear bands, which had a wide variety of thicknesses. These\nevolved regions have well-defined edges, which rules out local temperature rise\nas a possible formation mechanism. No structural evolution was found in areas\naway from the shear bands, even in locations where significant plastic\ndeformation had occurred, showing that plastic strain alone is not enough to\ncause evolution. Rather, intense strain localization is needed to induce\nmechanically-driven grain growth in a thermally-stable nanocrystalline alloy."
    },
    {
        "anchor": "Visualizing buried local carrier diffusion in halide perovskite crystals\n  via two-photon microscopy: Halide perovskites have shown great potential for light emission and\nphotovoltaic applications due to their remarkable electronic properties and\ncompatibility with cost-effective fabrication techniques. Although the device\nperformances are promising, they are still limited by microscale\nheterogeneities in their photophysical properties. In particular, the relation\nbetween local heterogeneities and the diffusion of charge carriers at the\nsurface and in the bulk, crucial for efficient collection of charges in a light\nharvesting device, is not well understood. Here, a photoluminescence tomography\ntechnique is developed in a confocal microscope using one- and two-photon\nexcitation to distinguish between local surface and bulk diffusion of charge\ncarriers in methylammonium lead bromide single crystals. The local temporal\ndiffusion is probed at various excitation depths to build statistics of local\nelectronic diffusion coefficients. The measured values range between 0.3 to 2\n$cm^2.s^{-1}$ depending on the local trap density and the morphological\nenvironment - a distribution that would be missed from analogous macroscopic or\nsurface-measurements. Tomographic images of carrier diffusion were\nreconstructed to reveal buried crystal defects that act as barriers to carrier\ntransport. This work reveals a new framework to understand and homogenise\ndiffusion pathways, which are extremely sensitive to local properties and\nburied defects.",
        "positive": "Elastic and Piezoresistive Properties of Nickel Carbides from\n  First-Principles: The nickel--carbon system has received increased attention over the past\nyears due to the relevance of nickel as a catalyst for carbon nanotube and\ngraphene growth, where Nickel carbide intermediates may be involved or carbide\ninterface layers form in the end. Nickel--carbon composite thin films\ncomprising Ni$_3$C are especially interesting in mechanical sensing\napplications. Due to the meta-stability of nickel carbides, formation\nconditions and the coupling between mechanical and electrical properties are\nnot yet well understood. Using first-principles electronic structure methods,\nwe calculated the elastic properties of Ni$_3$C, Ni$_2$C and NiC, as well as\nchanges in electronic properties under mechanical strain. We observe that the\nelectronic density of states around the Fermi level does not change under the\nconsidered strains of up to 1%, which correspond to stresses up to 3GPa.\nRelative changes in conductivity of Ni$_3$C range up to maximum values of about\n10%."
    },
    {
        "anchor": "GHz-Band Integrated Magnetic Inductors: The demand on mobile electronics to continue to shrink in size while increase\nin efficiency drives the demand on the internal passive components to do the\nsame. Power amplifiers require inductors with small form factors, high quality\nfactors, and high operating frequency in the single-digit GHz range. This work\nexplores the use of magnetic materials to satisfy the needs of power amplifier\ninductor applications. This paper discusses the optimization choices regarding\nmaterial selection, device design, and fabrication methodology. The inductors\nachieved here present the best performance to date for an integrated magnetic\ncore inductor at high frequencies with a 1 nH inductance and peak quality\nfactor of 4 at ~3 GHz. Such compact inductors show potential for efficiently\nmeeting the need of mobile electronics in the future.",
        "positive": "Experimental and theoretical study of the influence of disorder on\n  diffuse first-order phase transitions: NaNbO3: Gd and KTaO3: Li as examples: We consider consequences of local disorder in systems experiencing first\norder phase transitions. Such systems can be of rather different nature. For\nexample, manganates showing gigantic magnetoelectric effect, doped\nantiferroelectrics or biomembranes. Monte-Carlo computations performed have\nshown that the disorder increases the temperature interval where the high- and\nlowtemperature phases coexist and this provides thermodynamics in the\ndisordered systems distinct from the thermodynamics of classical homogeneous\nsystems."
    },
    {
        "anchor": "Simultaneous current-, force- and work function measurement with atomic\n  resolution: The local work function of a surface determines the spatial decay of the\ncharge density at the Fermi level normal to the surface. Here, we present a\nmethod that enables simultaneous measurements of local work function and\ntip-sample forces. A combined dynamic scanning tunneling microscope and atomic\nforce microscope is used to measure the tunneling current between an\noscillating tip and the sample in real time as a function of the cantilever's\ndeflection. Atomically resolved work function measurements on a silicon\n(111)-($7\\times 7$) surface are presented and related to concurrently recorded\ntunneling current- and force- measurements.",
        "positive": "Closing the gap between atomic-scale lattice deformations and continuum\n  elasticity: Crystal lattice deformations can be described microscopically by explicitly\naccounting for the position of atoms or macroscopically by continuum\nelasticity. In this work, we report on the description of continuous elastic\nfields derived from an atomistic representation of crystalline structures that\nalso include features typical of the microscopic scale. Analytic expressions\nfor strain components are obtained from the complex amplitudes of the Fourier\nmodes representing periodic lattice positions, which can be generally provided\nby atomistic modeling or experiments. The magnitude and phase of these\namplitudes, together with the continuous description of strains, are able to\ncharacterize crystal rotations, lattice deformations, and dislocations.\nMoreover, combined with the so-called amplitude expansion of the phase-field\ncrystal model, they provide a suitable tool for bridging microscopic to\nmacroscopic scales. This study enables the in-depth analysis of elasticity\neffects for macro- and mesoscale systems taking microscopic details into\naccount."
    },
    {
        "anchor": "Composition and structure of the RuO2(110) surface in an O2 and CO\n  environment: implications for the catalytic formation of CO2: The phase diagram of surface structures for the model catalyst RuO2(110) in\ncontact with a gas environment of O2 and CO is calculated by density-functional\ntheory and atomistic thermodynamics. Adsorption of the reactants is found to\ndepend crucially on temperature and partial pressures in the gas phase.\nAssuming that a catalyst surface under steady-state operation conditions is\nclose to a constrained thermodynamic equilibrium, we are able to rationalize a\nnumber of experimental findings on the CO oxidation over RuO2(110). We also\ncalculated reaction pathways and energy barriers. Based on the various results\nthe importance of phase coexistence conditions is emphasized as these will lead\nto an enhanced dynamics at the catalyst surface. Such conditions may actuate an\nadditional, kinetically controlled reaction mechanism on RuO2(110).",
        "positive": "Low entropy in graphene through the Co-C system: Uniform, mostly single-layer graphene with enhanced stability is demonstrated\nover Co film. The polycrystalline Co film deposited on a SiO2/Si substrate\ngives a continuous graphene layer that is easily transferred without the aid of\nany polymeric support, but preserving the material quality, as evidenced by\nRaman analysis. Great stability to the damaging action of the laser beam, as\ncompared to the Cu-grown material is also observed. The better structural and\nelectrical properties of the material are interpreted in terms of\nthermodynamics of the cooling-down process. It is suggested that the reduction\nin entropy, due annihilation of vacancies caused by C atoms precipitating\nduring cooling, directly depends on the activation energy of C solubility into\nCo, which is considerably high, due to Co magnetic ordering at the process\ntemperature. Our work expands the possibility of synthesizing single-layer\ngraphene keeping into account the thermodynamics of various C-metal systems."
    },
    {
        "anchor": "Impact of interfaces on the radiation response and underlying defect\n  recovery mechanisms in nanostructured Cu-Fe-Ag: Newest developments in nuclear fission and fusion technology as well as\nplanned long-distance space missions demand novel materials to withstand harsh,\nirradiative environments. Radiation-induced hardening and embrittlement are a\nconcern that can lead to failure of materials deployed in these applications.\nHere the underlying mechanisms are accommodation and clustering of lattice\ndefects created by the incident radiation particles. Interfaces, such as free\nsurfaces, phase and grain boundaries, are known for trapping and annihilating\ndefects and therefore preventing these radiation-induced defects from forming\nclusters. In this work, differently structured nanocomposite materials based on\nCu-Fe-Ag were fabricated using a novel solid-state route, combining severe\nplastic deformation with thermal and electrochemical treatments. The influence\nof different interface types and spacings on radiation effects in these\nmaterials was investigated using nanoindentation. Interface-rich bulk\nnanocomposites showed a slight decrease in hardness after irradiation, whereas\nthe properties of a nanoporous material remain mostly unchanged. An explanation\nfor this different material behavior and its link to recovery mechanisms at\ninterfaces is attempted in this work, paving a concept towards radiation\nresistant materials.",
        "positive": "Theory of Size-Driven Transitions in Displacive and Order-Disorder\n  Ferroelectrics: We present a simple theory for structural transitions in displacive\nferroelectrics of the perovskite type. In our theory, the competition between\nthe elastic energy cost for the displacement of the homopolar ion from the\ncentrosymmetric position, and the energy gain due to a ferroelectric ordering\nof the dipoles formed by the ionic displacements, leads naturally to a\nfirst-order transition from a paraelectric to a ferroelectric phase. This\ntransition takes place at a certain temperature $T_c(L)$ as the temperature is\ndecreased and, at a certain size $L_c (T)$ as the size of the system is\nincreased. The transition temperature $T_c (L)$ is suppressed as the sample\nsize is reduced, and vanishes for samples below a certain size. For\norder-disorder ferroelectrics, our theory shows that the suppression of $T_c$\nby a reduction in system size is not appreciable, a result that is borne out by\nexperiments."
    },
    {
        "anchor": "Theory of De-Pinning of Monolayer Films Adsorbed on a Quartz Crystal\n  Microbalance: In quartz crystal microbalance (QCM) studies of the friction between an\nadsorbed monolayer film and a metallic substrate, the films are observed to\nslide relative to the substrate under inertial forces of order $10^{-14}dyn$\nper film atom, a force much smaller than all theoretical estimates of the force\nthat surface defects are capable of exerting. In this letter we propose, in\norder to resolve this issue, that if the defect potentials have a range of\ngreater than an atomic spacing, the net force on a relatively stiff film due to\nthe defects is likely to be extremely small. Line defects (e.g., step and facet\nedges and grain boundaries) as well as more localized defects (e.g., vacancies)\nare considered.",
        "positive": "Expanding the tunability and applicability of exchange-coupled/decoupled\n  magnetic nanocomposites: CoFe2O4/Co-Fe magnetic composites are usually prepared through partial\nreduction of CoFe2O4, which often yields monoxides (i.e., FeO, CoO) as\nsecondary phases. Since these compounds are paramagnetic at ambient conditions,\nthe presence of a small amount of monoxide is generally downplayed in the\nliterature, and the possible effects on the magnetic properties are simply\nignored. However, the present study shows that even a low concentration of\nmonoxide results in decoupling of the soft and hard magnetic phases, which\ninevitably leads to a deterioration of the magnetic properties. Additionally,\nit is confirmed that a partial reduction of CoFe2O4 is a suitable method to\nproduce CoFe2O4/Co-Fe nanocomposites, provided that the treatment is well\ncontrolled with respect to duration, temperature and flow of reductant. A\nmonoxide-free nanocomposite was produced and its magnetic properties evaluated\nboth at room and low temperature. Our model system exemplifies the potential of\nexchange-coupling (and decoupling) as a tool to tune the magnetic properties of\na material within a relatively wide range of values, thus widening its spectrum\nof potential applications."
    },
    {
        "anchor": "Gap opening and large spin-orbit splitting in MX2 (M=Mo,W X=S,Se,Te)\n  from the interplay between crystal field and hybridizations: insights from\n  ab-initio theory: By means of first-principles density functional calculations, we study the\nmaximally localized Wannier functions for the 2D transition metal\ndichalcogenides MX2 (M=Mo,W X=S,Se,Te). We found a M^+4-like ionic charge and a\nsingle occupied d-band. The center of the d-like maximally localized Wannier\nfunction associated with this band is distributed among three M sites. Part of\nthe energy gap is opened by the crystal field splitting induced by the\nX^-2-like atoms. We extract the hopping parameters for the Wannier functions\nand provide a perspective on tight-binding model. From the analysis of the\ntight binding model, we have found an inversion of the band character between\nthe Gamma and the K points of the Brillouin zone due to the M-M hybridization.\nThe consequence of this inversion is the closure of the gap. The M-X\nhybridization is the only one that tends to open the gap at every k-point, the\nchange in the M-X and M-M hybridization is the main responsible for the\ndifference in the gap between the different dichalcogenide materials. The\ninversion of the bands gives rise to different spin-orbit splitting at Gamma\nand K point in the valence band. The different character of the gap at Gamma\nand K point offers the chance to manipulate the semiconductive properties of\nthese compounds. For a bilayer system, the hybridizations between the out of\nplane orbitals and the hybridizations between the in plane orbitals split the\nvalence band respectively at the Gamma and K point. The splitting in the\nvalence band is opened also without spin-orbit coupling and comes from the M-M\nand X-X hybridization between the two monolayers.",
        "positive": "Vibrational contribution to the thermodynamics of nanosized\n  precipitates: vacancy-copper clusters in bcc-Fe: Within the harmonic approximation, the effects of lattice vibration on the\nthermodynamics of nano-sized coherent clusters in bcc-Fe consisting of\nvacancies and/or copper are investigated. A combination of on-lattice simulated\nannealing based on Metropolis Monte Carlo simulations and off-lattice\nrelaxation by Molecular Dynamics is applied to obtain the most stable cluster\nconfigurations at T = 0 K. The most recent interatomic potential built within\nthe framework of the embedded atom method for the Fe-Cu system is used. The\nvibrational part of the total free energy of defect clusters in bcc-Fe is\ncalculated using their phonon density of states. The total free energy of pure\nbcc-Fe and fcc-Cu as well as the total formation free energy and the total\nbinding free energy of the vacancy-copper clusters are determined for finite\ntemperatures. Our results are compared with the available data from previous\ninvestigations performed using empirical many-body interatomic potentials and\nfirst-principle methods. For further applications in rate theory and object\nkinetic Monte Carlo simulations, the vibrational effects evaluated in the\npresent study are included in the previously derived analytical fits based on\nthe classical capillary model."
    },
    {
        "anchor": "LAN -- A materials notation for 2D layered assemblies: Two-dimensional (2D) layered materials offer intriguing possibilities for\nnovel physics and applications. Before any attempt at exploring the materials\nspace in a systematic fashion, or combining insights from theory, computation\nand experiment, a formal description of information about an assembly of\narbitrary composition is required. Here, we introduce a domain-generic notation\nthat is used to describe the space of 2D layered materials from monolayers to\ntwisted assemblies of arbitrary composition, existent or not-yet-fabricated.\nThe notation corresponds to a theoretical materials concept of stepwise\nassembly of layered structures using a sequence of rotation, vertical stacking,\nand other operations on individual 2D layers. Its scope is demonstrated with a\nnumber of example structures using common single-layer materials as building\nblocks. This work overall aims to contribute to the systematic codification,\ncapture and transfer of materials knowledge in the area of 2D layered\nmaterials.",
        "positive": "Phonon Lifetimes and Thermal Conductivity of the Molecular Crystal\n  $\u03b1$-RDX: The heat transfer properties of the organic molecular crystal ${\\alpha}$-RDX\nwere studied using three phonon-based thermal conductivity models. It was found\nthat the widely used Peierls-Boltzmann model for thermal transport in\ncrystalline materials breaks down for ${\\alpha}$-RDX. We show this breakdown is\ndue to a large degree of anharmonicity that leads to a dominance of\ndiffusive-like carriers. Despite being developed for disordered systems, the\nAllen-Feldman theory for thermal conductivity actually gives the best\ndescription of thermal transport. This is likely because diffusive carriers\ncontribute to over 95% of the thermal conductivity in ${\\alpha}$-RDX. The\ndominance of diffusive carriers is larger than previously observed in other\nfully ordered crystalline systems. These results indicate than van-der Waals\nbonded organic crystalline solids conduct heat in a manner more akin to\namorphous materials than simple atomic crystals."
    },
    {
        "anchor": "Non-contact mutual inductance based measurement of an inhomogeneous\n  topological insulating state in Bi2Se3 single crystals with defects: Pure Topological Insulating materials preserve a unique electronic state\ncomprising of bulk insulating gap and conducting surface states. Here we use\nbulk Bi2Se3 single crystals possessing Se vacancy defects as a prototype\ntopological insulator (TI) material for exploring the effect of non-magnetic\ndisorder on the conducting properties of TIs. We employ a sensitive,\nnon-contact, mutual inductance based technique for measuring the surface and\nbulk contribution to electrical conductivity in the TI. We discern the\ndifferent contributions, by observing that predominant surface electrical\nconduction produces linear frequency dependence of the pickup signal while bulk\nconductivity gives rise to quadratic frequency dependence. We also see an\nalgebraic temperature dependent surface conductivity while an activated bulk\nconductivity. Using the above we uncover an interplay between surface and bulk\ncontribution to electrical conductivity in the TI as a function of\ntemperatures. In the Bi2Se3 crystals the transformation from surface to bulk\ndominated electrical transport is found to occur close to 70 K. This\ntemperature range matches well with our results from activated bulk electrical\ntransport results which shows an activation energy scale, delta which is in the\nmillieV range. The gap delta is much less than the bulk band gap in Bi2Se3, and\nwhich we argue is associated with defect states in the TI material. To\nunderstand our results, we propose a model of a TI comprising of an\ninhomogeneous low electrically conducting medium (bulk) which is sandwiched\nbetween thin two high electrically conducting sheets (surface). The\ninhomogeneous TI state we argue is generated by Selenium vacancies defects in\nBi2Se3, which is responsible for producing an interplay between bulk and\nsurface conductivity.",
        "positive": "Impurity-induced tuning of quantum well states in spin-dependent\n  resonant tunneling: We report exact model calculations of the spin-dependent tunneling in double\nmagnetic tunnel junctions in the presence of impurities in the well. We show\nthat the impurity can tune selectively the spin channels giving rise to a wide\nvariety of interesting and novel transport phenomena. The tunneling\nmagnetoresistance, the spin polarization and the local current can be\ndramatically enhanced or suppressed by impurities. The underlying mechanism is\nthe impurity-induced shift of the quantum well states (QWS) which depends on\nthe impurity potential, impurity position and the symmetry of the QWS."
    },
    {
        "anchor": "Crumpling an elasto-plastic thin sphere: The phenomenon of crumpling is common in our daily life and nature. It\nexhibits many interesting properties, such as ultra-tough resistance to\npressure with less than 30$\\%$ of volume density, power-law relation for\npressure vs density, and crackling noises with occurrence frequency vs\nintensity mimicking that of earthquakes. These results are mainly obtained by\nusing flat thin sheets. But, in reality the majority of crumpled objects\nexhibit nonzero intrinsic curvatures. Notable examples are crushed aluminum\ncans, car wreckage, and cells move in and out of blood vessels. In this work we\nconcentrate on establishing the fact that they behave very differently from\nflat sheets by employing both experiments and molecular dynamics simulations.",
        "positive": "First-principles study of ferroelectric oxide epitaxial thin films and\n  superlattices: role of the mechanical and electrical boundary conditions: In this review, we propose a summary of the most recent advances in the\nfirst-principles study of ferroelectric oxide epitaxial thin films and\nmultilayers. We discuss in detail the key roles of mechanical and electrical\nboundary conditions, providing to the reader the basic background for a simple\nand intuitive understanding of the evolution of the ferroelectric properties in\nmany nanostructures. Going further we also highlight promising new avenues and\nfuture challenges within this exciting field or researches."
    },
    {
        "anchor": "Basis set construction for molecular electronic structure theory:\n  Natural orbital and Gauss-Slater basis for smooth pseudpotentials: A simple yet general method for constructing basis sets for molecular\nelectronic structure calculations is presented. These basis sets consist of\natomic natural orbitals from a multi-configurational self-consistent field\ncalculation supplemented with primitive functions, chosen such that the\nasymptotics are appropriate for the potential of the system. Primitives are\noptimized for the homonuclear diatomic molecule to produce a balanced basis\nset. Two general features that facilitate this basis construction are\ndemonstrated. First, weak coupling exists between the optimal exponents of\nprimitives with different angular momenta. Second, the optimal primitive\nexponents for a chosen system depend weakly on the particular level of theory\nemployed for optimization. The explicit case considered here is a basis set\nappropriate for the Burkatzki-Filippi-Dolg pseudopotentials. Since these\npseudopotentials are finite at nuclei and have a Coulomb tail, the recently\nproposed Gauss-Slater functions are the appropriate primitives. Double- and\ntriple-zeta bases are developed for elements hydrogen through argon. These new\nbases offer significant gains over the corresponding Burkatzki-Filippi-Dolg\nbases at various levels of theory. Using a Gaussian expansion of the basis\nfunctions, these bases can be employed in any electronic structure method.\nQuantum Monte Carlo provides an added benefit: expansions are unnecessary since\nthe integrals are evaluated numerically.",
        "positive": "Investigation of the electronic properties of the surface and bulk forms\n  of gold and palladium: The density of electronic states for bulk metals Au and Pd, their surfaces in\nthe form of polycrystalline surface layers of nanometer thickness is\ninvestigated. The calculations were performed using density functional theory\nwith pseudopotential in full relativistic approximation. Approximations have\nbeen found that provide calculations the density of electronic states of noble\nmetal surfaces that describe the experimentally observed features of XPS\nspectra of the valence band of these metals."
    },
    {
        "anchor": "Efficient Charge-Spin Conversion and Magnetization Switching though\n  Rashba Effect at Topological Insulator/Ag Interface: We report the observation of efficient charge-to-spin conversion in the\nthree-dimensional topological insulator (TI) Bi2Se3 and Ag bilayer by the\nspin-torque ferromagnetic resonance technique. The spin orbit torque ratio in\nthe Bi2Se3/Ag/CoFeB heterostructure shows a significant enhancement as the Ag\nthickness increases to ~2 nm and reaches a value of 0.5 for 5 nm Ag, which is\n~3 times higher than that of Bi2Se3/CoFeB at room temperature. The observation\nreveals the interfacial effect of Bi2Se3/Ag exceeds that of the topological\nsurface states (TSS) in the Bi2Se3 layer and plays a dominant role in the\ncharge-to-spin conversion in the Bi2Se3/Ag/CoFeB system. Based on the\nfirst-principles calculations, we attribute our observation to the large\nRashba-splitting bands which wrap the TSS band and has the same net spin\npolarization direction as TSS of Bi2Se3. Subsequently, we demonstrate for the\nfirst time the Rashba induced magnetization switching in Bi2Se3/Ag/Py with a\nlow current density of 5.8 X 10^5 A/cm2.",
        "positive": "First-principles approach to electric polarization and dielectric\n  constant calculations using generalized Wannier functions: We describe a method to calculate the electronic properties of an insulator\nunder an applied electric field. It is based on the minimization of an electric\nenthalpy functional with respect to the orbitals, which behave as Wannier\nfunctions under crystal translations, but are not necessarily orthogonal. This\npaper extends the approach of Nunes and Vanderbilt (NV) [Phys. Rev. Lett. 73,\n712 (1994)], who demonstrated that a Wannier function representation can be\nused to study insulating crystals in the presence of a finite electric field.\nAccording to a study by Fern\\'{a}ndez et al. [Phys. Rev. B. 58, R7480 (1998)],\nfirst-principles implementations of the NV approach suffer from the impact of\nthe localization constraint on the orthogonal wave functions, what affects the\naccuracy of the physical results. We show that because non-orthogonal\ngeneralized Wannier functions can be more localized than their orthogonal\ncounterparts, the error due to localization constraints is reduced, thus\nimproving the accuracy of the calculated physical quantities."
    },
    {
        "anchor": "Quasiparticles and phonon satellites in spectral functions of\n  semiconductors and insulators: Cumulants applied to full first principles\n  theory and Fr\u00f6hlich polaron: The electron-phonon interaction causes thermal and zero-point motion shifts\nof electron quasiparticle (QP) energies $\\epsilon_k(T)$. Other consequences of\ninteractions, visible in angle-resolved photoemission spectroscopy (ARPES)\nexperiments, are broadening of QP peaks and appearance of sidebands, contained\nin the electron spectral function\n  $A(k,\\omega)=-{\\Im m}G_R(k,\\omega) /\\pi$, where $G_R$ is the retarded Green's\nfunction. Electronic structure codes (e.g. using density-functional theory) are\nnow available that compute the shifts and start to address broadening and\nsidebands. Here we consider MgO and LiF, and determine their nonadiabatic\nMigdal self energy. The spectral function obtained from the Dyson equation\nmakes errors in the weight and energy of the QP peak and the position and\nweight of the phonon-induced sidebands. Only one phonon satellite appears, with\nan unphysically large energy difference (larger than the highest phonon energy)\nwith respect to the QP peak. By contrast, the spectral function from a cumulant\ntreatment of the same self energy is physically better, giving a quite accurate\nQP energy and several satellites approximately spaced by the LO phonon energy.\nIn particular, the positions of the QP peak and first satellite agree closely\nwith those found for the Fr\\\"ohlich Hamiltonian by Mishchenko $\\textit{et al.}$\n(2000) using diagrammatic Monte Carlo. We provide a detailed comparison between\nthe first-principles MgO and LiF results and those of the Fr\\\"ohlich\nHamiltonian. Such an analysis applies widely to materials with infra-red active\nphonons. We also compare the retarded and time-ordered cumulant treatments:\nthey are equivalent for the Fr\\\"ohlich Hamiltonian, and only slightly differ in\nfirst-principles electron-phonon results for wide-band gap materials.",
        "positive": "Giant enhancement of spin pumping efficiency using Fe3Si ferromagnet: Spincurrentronics, which involves the generation, propagation and control of\nspin currents, has attracted a great deal of attention because of the\npossibility of realizing dissipation-free information propagation. Whereas\nelectrical generation of spin currents originally made the field of\nspincurrentronics possible, and significant advances in spin-current devices\nhas been made, novel spin-current-generation approaches such as dynamical\nmethods have also been vigorously investigated. However, the low spin-current\ngeneration efficiency associated with dynamical methods has impeded further\nprogress towards practical spin devices. Here we show that by introducing a\nHeusler-type ferromagnetic material, Fe3Si, pure spin currents can be generated\nabout twenty times more efficiently using a dynamical method. This achievement\npaves the way to the development of novel spin-based devices."
    },
    {
        "anchor": "Exsolution of oxygen impurity from diamond lattice and formation of\n  pressurized CO2-I precipitates: Diamond single crystals showing Infra-red features of pressurized CO2-I phase\nwere studied using Transmission Electron Microscopy (TEM) and tomography.\nNumerous O-containing precipitates with sizes up to 45 nm are observed. The\nabsolute majority of these precipitates decorate dislocation loops or are\nlocated inside them; individual scattered precipitates are also present.\nMorphology of the precipitates varies from quasi-isometric octahedra to highly\nflattened elongated ones. Close association of the precipitates with the\ndislocation loops implies their formation by exsolution of oxygen impurity from\ndiamond lattice; the size distribution of the precipitates suggests that the\nequilibrium state is not yet reached. Presumably, the morphology and precise\nchemical composition depend on P-T-t evolution of the diamond crystal and\ncorresponding changes in oxygen supersaturation in the lattice. The\nCO2-containing diamonds often contain micron-sized hexagonal lamellar\ninclusions. TEM investigation of a lamellae reveals that it consists of high\nquality graphite showing partial epitaxial relation with comprising diamond.\nThe gap between the graphite and diamond may be enriched with oxygen impurity.",
        "positive": "Sputter gas pressure effects on the properties of Sm-Co thin films\n  deposited from a single target: We grow epitaxial Sm-Co thin films by sputter deposition from an alloy target\nwith a nominal SmCo5 composition on Cr(100)-buffered MgO(100) single-crystal\nsubstrates. By varying the Ar gas pressure, we can change the composition of\nthe film from a SmCo5-like to a Sm2Co7-like phase. The composition, crystal\nstructure, morphology and magnetic properties of these films have been\ndetermined using Rutherford Backscattering, X-ray diffraction and magnetization\nmeasurements. We find that the various properties are sensitive to the sputter\nbackground pressure in different ways. In particular, the lattice parameter\nchanges in a continuous way, the coercive fields vary continuously with a\nmaximum value of 3.3 T, but the saturation magnetization peaks when the lattice\nparameter is close to that of Sm2Co7. Moreover, we find that the Sm content of\nthe films is higher than expected from the expected stoichiometry."
    },
    {
        "anchor": "Critical behavior of two-dimensional intrinsically ferromagnetic\n  semiconductor CrI3: CrI3, which belongs to a rare category of two-dimensional (2D) ferromagnetic\nsemiconductors, is of great interest for spintronic device applications. Unlike\nCrCl3 whose magnetism presents a 2D-Heisenberg behavior, CrI3 exhibits a larger\nvan der Waals gap, smaller cleavage energy, and stronger magnetic anisotropy\nwhich could lead to a 3D magnetic characteristic. Hence, we investigate the\ncritical behavior of CrI3 in the vicinity of magnetic transition. We use the\nmodified Arrott plot and Kouvel-Fisher method, and conduct critical isotherm\nanalysis to estimate the critical exponents near the ferromagnetic phase\ntransition. This shows that the magnetism of CrI3 follows the crossover\nbehavior of a 3D-Ising model with mean field type interactions where the\ncritical exponents \\b{eta}, {\\gamma}, and {\\delta} are 0.323, 0.835, and 3.585,\nrespectively, at the Curie temperature of 64 K. We propose the crossover\nbehavior can be attributed to the strong uniaxial anisotropy and inevitable\ninterlayer coupling. Our experiment demonstrates the applicability of crossover\nbehavior to a 2D ferromagnetic semiconductor.",
        "positive": "Molecular Simulations of Shock to Detonation Transition in Nitromethane: An extension of the model described in a previous work of Maillet, Soulard\nand Stoltz based on a Dissipative Particule Dynamics is presented and applied\nto liquid nitromethane. Large scale non-equilibrium simulations of reacting\nnitromethane under sustained shock conditions allow a better understanding of\nthe shock-to-detonation transition in homogeneous explosives. Moreover, the\npropagation of the reactive wave appears discontinuous since ignition points in\nthe shocked material can be activated by the compressive waves emitted from the\nonset of chemical reactions."
    },
    {
        "anchor": "Tip-induced oxidation of silicene nano-ribbons: We report on the oxidation of self-assembled silicene nanoribbons grown on\nthe Ag(110) surface using Scanning Tunneling Microscopy and High-Resolution\nPhotoemission Spectroscopy. The results show that silicene nanoribbons present\na strong resistance towards oxidation using molecular oxygen. This can be\novercome by increasing the electric field in the STM tunnel junction above a\nthreshold of +2.6 V to induce oxygen dissociation and reaction. The higher\nreactivity of the silicene nanoribbons towards atomic oxygen is observed as\nexpected. The HR-PES confirm these observations: Even at high exposures of\nmolecular oxygen, the Si 2p core-level peaks corresponding to pristine silicene\nremain dominant, reflecting a very low reactivity to molecular oxygen. Complete\noxidation is obtained following exposure to high doses of atomic oxygen; the Si\n2p core level peak corresponding to pristine silicene disappears.",
        "positive": "Near-Field Scanning Microwave Microscopy: Measuring Local Microwave\n  Properties and Electric Field Distributions: We describe the near-field microwave microscopy of microwave devices on a\nlength scale much smaller than the wavelength used for imaging. Our microscope\ncan be operated in two possible configurations, allowing a quantitative study\nof either material properties or local electric fields."
    },
    {
        "anchor": "Topological Signatures in Nodal Semimetals through Neutron Scattering: Topological nodal semimetals are known to host a variety of fascinating\nelectronic properties due to the topological protection of the band-touching\nnodes. Neutron scattering, despite its power in probing elementary excitations,\nhas not been routinely applied to topological semimetals, mainly due to the\nlack of an explicit connection between the neutron response and the signature\nof topology. In this work, we theoretically investigate the role that neutron\nscattering can play to unveil the topological nodal features: a large magnetic\nneutron response with spectral non-analyticity can be generated solely from the\nnodal bands. A new formula for the dynamical structure factor for generic\ntopological nodal metals is derived. For Weyl semimetals, we show that the\nlocations of Weyl nodes, the Fermi velocities and the signature of chiral\nanomaly can all leave hallmark neutron spectral responses. Our work offers a\nneutron-based avenue towards probing bulk topological materials.",
        "positive": "Spontaneous Distortion and Ferromagnetism Induced by Quantum-well States\n  in Pd(100) Ultrathin Films: We study the crystal structure of Pd(100) ultrathin films, which show\nferromagnetism induced by the quantum confinement effect, using in-situ X-ray\ncrystal truncation rod measurement and density functional calculation. The\nenergy gain due to the appearance of ferromagnetism in Pd results in flatter\nand uniform film growth of ferromagnetic Pd films compared with paramagnetic\nPd. In addition, ferromagnetic Pd films expand the lattice constant in order to\nsuppress the increase in kinetic energy of electrons accompanied by the\noccurrence of exchange splitting. Although the traditional theory of magnetism\nin metals indicates that the increase in density of states that induces\nferromagnetism (Stoner criterion), our present finding reveals a mechanism of\nmodulation in the density of states via the appearance of ferromagnetism, i.e.,\nthe inverse mechanism of Stoner's theory."
    },
    {
        "anchor": "Ultrafast photocurrents at the surface of the three-dimensional\n  topological insulator $\\mathrm{Bi}_2\\mathrm{Se}_3$: Topological insulators constitute a new and fascinating class of matter with\ninsulating bulk yet metallic surfaces that host highly mobile charge carriers\nwith spin-momentum locking. Remarkably, the direction and magnitude of surface\ncurrents can be controlled with tailored light beams, but the underlying\nmechanisms are not yet well understood. To directly resolve the \"birth\" of such\nphotocurrents we need to boost the time resolution to the scale of elementary\nscattering events ($\\sim$ 10 fs). Here, we excite and measure photocurrents in\nthe three-dimensional model topological insulator $\\mathrm{Bi}_2\\mathrm{Se}_3$\nwith a time resolution as short as 20 fs by sampling the concomitantly emitted\nbroadband THz electromagnetic field from 1 to 40 THz. Remarkably, the ultrafast\nsurface current response is dominated by a charge transfer along the Se-Bi\nbonds. In contrast, photon-helicity-dependent photocurrents are found to have\norders of magnitude smaller magnitude than expected from generation scenarios\nbased on asymmetric depopulation of the Dirac cone. Our findings are also of\ndirect relevance for optoelectronic devices based on topological-insulator\nsurface currents.",
        "positive": "Tight-binding model and direct-gap/indirect-gap transition in\n  single-layer and multi-layer MoS$_2$: In this paper we present a paradigmatic tight-binding model for single-layer\nas well as for multi-layered semiconducting MoS$_2$ and similar transition\nmetal dichalcogenides. We show that the electronic properties of multilayer\nsystems can be reproduced in terms of a tight-binding modelling of the\nsingle-layer hopping terms by simply adding the proper interlayer hoppings\nruled by the chalcogenide atoms. We show that such tight-binding model permits\nto understand and control in a natural way the transition between a direct-gap\nband structure, in single-layer systems, to an indirect gap in multilayer\ncompounds in terms of a momentum/orbital selective interlayer splitting of the\nrelevant valence and conduction bands. The model represents also a suitable\nplayground to investigate in an analytical way strain and finite-size effects."
    },
    {
        "anchor": "Magnetic field induced dehybridization of the electromagnons in\n  multiferroic TbMnO3: We have studied the impact of the magnetic field on the electromagnon\nexcitations in TbMnO3 crystal. Applying magnetic field along the c axis, we\nshow that the electromagnons transform into pure antiferromagnetic modes,\nlosing their polar character. Entering in the paraelectric phase, we are able\nto track the spectral weight transfer from the electromagnons to the magnon\nexcitations and we discuss the magnetic excitations underlying the\nelectromagnons. We also point out the phonons involved in the phase transition\nprocess. This reveals that the Mn-O distance plays a key role in understanding\nthe ferroelectricity and the polar character of the electromagnons. Magnetic\nfield measurements along the b axis allow us to detect a new electromagnon\nresonance in agreement with a Heisenberg model.",
        "positive": "Large in-plane negative piezoelectricity and giant nonlinear optical\n  susceptibility in elementary ferroelectric monolayers: Negative piezoelectrics contract in the direction of applied electric field,\nwhich are opposite to normal piezoelectrics and rare in dielectric materials.\nThe raising of low dimensional ferroelectrics, with unconventional mechanisms\nof polarity, opens a fertile branch for candidates with prominent negative\npiezoelectricity. Here, the distorted $\\alpha$-Bi monolayer, a newly-identified\nelementary ferroelectric with puckered black phosphorous-like structure [J.\nGuo, {\\it et al}. Nature \\textbf{617}, 67 (2023)], is computationally studied,\nwhich manifests a large negative in-plane piezoelectricity (with\n$d_{33}\\sim-26$ pC/N). Its negative piezoelectricity originates from its unique\nbuckling ferroelectric mechanism, namely the inter-column sliding.\nConsequently, a moderate tensile strain can significantly reduce its\nferroelectric switching energy barrier, while the compressive strain can\nsignificantly enhance its prominent nonlinear optical response. The physical\nmechanism of in-plane negative piezoelectricity also applies to other\nelementary ferroeletric monolayers."
    },
    {
        "anchor": "Multiphase hydrogen storage in nanocontainers: Hydrogen can be stored in containers or in materials. In materials it can\nexist in molecular or atomic forms. The atomic form can further exist as\nmultiple phases. Molecular hydrogen can be adsorbed on the surface or can be\npresent inside the material. In the current work, we demonstrate for the first\ntime, a methodology to store hydrogen in nearly all conceivable forms. At the\nheart of this strategy is the novel concept of storage of molecular hydrogen in\nmetal Pd nanocontainers. The existence of multiple phases of hydrogen is\nconfirmed by x ray diffraction, Raman spectroscopy, nuclear magnetic resonance\nand pressure-composition isotherm measurements. Enhancement in storage capacity\nas compared to nanocrystals of the same mass is observed (36 percent increase\nat 1 atm and 25C). About 18 percent of the hydrogen stored is in the molecular\nform and interestingly this is achieved at room temperature and 1 atm pressure.",
        "positive": "Doubly-charged silicon vacancy center, photochromism, and Si-N complexes\n  in co-doped diamond: We report the first experimental observation of a doubly-charged defect in\ndiamond, SiV2-, in silicon and nitrogen co-doped samples. We measure\nspectroscopic signatures we attribute to substitutional silicon in diamond, and\nidentify a silicon-vacancy complex decorated with a nearest-neighbor nitrogen,\nSiVN, supported by theoretical calculations. Samples containing silicon and\nnitrogen are shown to be heavily photochromic, with the dominant visible\nchanges due to the loss of SiV0/- and gain in the optically-inactive SiV2-."
    },
    {
        "anchor": "Planar Hall Effect MRAM: We suggest a new type of magnetic random access memory (MRAM) that is based\non the phenomenon of the planar Hall effect (PHE) in magnetic films, and we\ndemonstrate this idea with manganite films. The PHE-MRAM is structurally\nsimpler than currently developed MRAM that is based on magnetoresistance tunnel\njunctions (MTJ), with the tunnel junction structure being replaced by a single\nlayer film.",
        "positive": "Magnetoresistance in Hybrid Pt/CoFe2O4 Bilayers Controlled by Competing\n  Spin Accumulation and Interfacial Chemical Reconstruction: Pure spin currents hold promises for an energy-friendlier spintronics. They\ncan be generated by a flow of charge along a non-magnetic metal having a large\nspin-orbit coupling. It produces a spin accumulation at its surfaces,\ncontrollable by the magnetization of an adjacent ferromagnetic layer.\nParamagnetic metals typically used are close to a ferromagnetic instability and\nthus magnetic proximity effects can contribute to the observed\nangular-dependent magnetoresistance (ADMR). As interface phenomena govern the\nspin conductance across the metal/ferromagnetic-insulator heterostructures,\nunraveling these distinct contributions is pivotal to full understanding of\nspin current conductance. We report here x-ray absorption and magnetic circular\ndichroism (XMCD) at Pt-M and (Co,Fe)-L absorption edges and atomically-resolved\nenergy loss electron spectroscopy (EELS) data of Pt/CoFe2O4 bilayers where\nCoFe2O4 layers have been capped by Pt grown at different temperatures. It turns\nout that the ADMR differs dramatically, being either dominated by spin Hall\nmagnetoresistance (SMR) associated to spin Hall effect or anisotropic\nmagnetoresistance (AMR). The XMCD and EELS data indicate that the Pt layer\ngrown at room temperature does not display any magnetic moment, whereas when\ngrown at higher temperature it is magnetic due to interfacial Pt-(Co,Fe)\nalloying. These results allow disentangling spin accumulation from interfacial\nchemical reconstructions and for tailoring the angular dependent\nmagnetoresistance."
    },
    {
        "anchor": "Unique surface-state connection between Weyl and nodal ring fermions in\n  ferromagnetic material Cs2MoCl6: For topological materials with coexistence of Weyl nodes and nodal rings, the\nsurface-state configuration and connection are unique yet have never been\nstudied and discussed before. In this paper, we predict a ferromagnetic (FM)\nmaterial, Cs2MoCl6, with coexistence of Weyl and nodering fermions in its\nspinful FM electronic band structure, which is unusual since FM materials are\nvery rare in nature and node-ring band crossings will usually open a gap when\nspin-orbit coupling (SOC) is taken into consideration. We find that the surface\nstates of Cs2MoCl6 show different properties along different directions, i.e,\nthe surface states are in the drumhead shape showing the node-ring property on\nthe (001) surface and in the helicoid shape showing the Weyl property on the\n(010) surface. Interestingly, both the drumhead surface states and the helicoid\nsurface states will cross the projected points of the Weyl and nodal ring along\ndifferent directions. In particular, helicoid surface states on the (010)\nsurface will meet the nodal ring tangentially, with their shapes change\nabruptly as a function of the energy. We implement both first-principle\ncalculation and an analytical model to understand the unique surface-state\nconnection for systems with the coexistence of Weyl nodes and nodal rings (or\nnodal lines). This result is universal and irrespective of the presence/absence\nof and time-reversal symmetry (T).",
        "positive": "General and mechanistic optimal relationships for tensile strength of\n  doubly convex tablets under diametrical compression: We propose a general framework for determining optimal relationships for\ntensile strength of doubly convex tablets under diametrical compression. This\napproach is based on the observation that tensile strength is directly\nproportional to the breaking force and inversely proportional to a non-linear\nfunction of geometric parameters and materials properties. This generalization\nreduces to the analytical expression commonly used for flat faced tablets,\ni.e., Hertz solution, and to the empirical relationship currently used in the\npharmaceutical industry for convex-faced tablets, i.e., Pitt's equation. Under\nproper parametrization, optimal tensile strength relationship can be determined\nfrom experimental results by minimizing a figure of merit of choice. This\noptimization is performed under the first-order approximation that a flat faced\ntablet and a doubly curved tablet have the same tensile strength if they have\nthe same relative density and are made of the same powder, under equivalent\nmanufacturing conditions. Furthermore, we provide a set of recommendations and\nbest practices for assessing the performance of optimal tensile strength\nrelationships in general. Based on these guidelines, we identify two new\nmodels, namely the general and mechanistic models, which are effective and\npredictive alternatives to the tensile strength relationship currently used in\nthe pharmaceutical industry."
    },
    {
        "anchor": "Unexpected behaviour of the crystal growth velocity at the hypercooling\n  limit: The crystal growth velocity is one thermodynamic parameter of solidification\nexperiments of undercooled melts under non-equilibrium conditions, which is\ndirectly accessible to observation. We applied the electrostatic levitation\ntechnique in order to study the crystal growth velocity $v$ as a function of\nthe undercooling $\\Delta T$ for the intermetallic, congruently melting binary\nalloy NiTi and the glass forming alloy Cu--Zr, as well as for the Zr-based\nternary alloys (Cu$_{\\mathrm{x}}$Ni$_{\\mathrm{1-x}}$)Zr ($x= 0.7, 0.6$) and the\nNi-based ternary alloy Ni(Zr$_{\\mathrm{x}}$Ti$_{\\mathrm{1-x}}) (x= 0.5)$. All\ninvestigated systems within this work, except the eutectics $Cu_{56}Zr_{44}$\nand $Cu_{46}Zr_{54}$, exceeded the hypercooling limit $\\Delta T_{\\mathrm{hyp}}$\nand, remarkably, every $v(\\Delta T)$ relation changed significantly at $\\Delta\nT_{\\mathrm{hyp}}$. Our results for glass forming CuZr indicate that the\ninfluence of the diffusion coefficient $D(T)$ on $v(\\Delta T)$ at high\nundercoolings, as claimed in literature, cannot be the sole reason for the\nexistence of a maximum in the $v(\\Delta T)$ behaviour. These observations could\nmake a valuable contribution concerning an extension of growth theories to\nundercooling temperatures $\\Delta T > \\Delta T_{\\mathrm{hyp}}$. Nevertheless,\nour finding has direct consequences to various disciplines, as our earth and\nall living beings are examples for non-equilibrium systems. The scatter of our\nvelocity data is at least two orders of magnitude smaller than measurements\nperformed by former works due to our experimental setup, which allowed precise\ncontactless triggering at a specific undercooling, and our analysis method,\nwhich considered the respective solidification morphologies.",
        "positive": "Surfaces of Axion Insulators: Axion insulators are magnetic topological insulators in which the non-trivial\n$\\mathbb{Z}_2$ index is protected by inversion symmetry instead of\ntime-reversal symmetry. The naturally gapped surfaces of axion insulators give\nrise to a half-quantized surface anomalous Hall conductivity (AHC), but the\nsign of the surface AHC cannot be determined from topological arguments. In\nthis paper, we consider topological phenomena at the surface of an axion\ninsulator. To be explicit, we construct a minimal tight-binding model on the\npyrochlore lattice and investigate the all-in-all-out (AIAO) and ferromagnetic\n(FM) spin configurations. We also implement a recently proposed approach for\ncalculating the surface AHC directly, which allows us to explore how the\ninterplay between surface termination and magnetic ordering determines the sign\nof the half-quantized surface AHC. In the case of AIAO ordering, we show that\nit is possible to construct a topological state with no protected metallic\nstates on boundaries of any dimension (surfaces, hinges, or corners), although\nchiral hinge modes do occur for many surface configurations. In the FM case,\nrotation of the magnetization by an external field offers a promising means of\ncontrol of chiral hinge modes, which can also appear on surface steps or where\nbulk domain walls emerge at the surface."
    },
    {
        "anchor": "Sharp interface model for solid-state dewetting problems with weakly\n  anisotropic surface energies: We propose a sharp interface model for simulating solid-state dewetting where\nthe surface energy is (weakly) anisotropic. The morphology evolution of thin\nfilms is governed by surface diffusion and contact line migration. The\nmathematical model is based on an energy variational approach. Anisotropic\nsurface energies lead to multiple solutions of the contact angle equation at\ncontact points. Introduction of a finite contact point mobility is both\nphysically based and leads to robust, unambiguous determination of the contact\nangles. We implement the mathematical model in an explicit finite difference\nscheme with cubic spline interpolation for evolving marker points. Following\nvalidation of the mathematical and numerical approaches, we simulate the\nevolution of thin film islands, semi-infinite films, and films with holes as a\nfunction of film dimensions, Young's angle $\\theta_i$, anisotropy strength and\ncrystal symmetry, and film crystal orientation relative to the substrate\nnormal. We find that the contact point retraction rate can be well described by\na power-law, $l \\sim t^n$. Our results demonstrate that the exponent $n$ is not\nuniversal -- it is sensitive to the Young's angle $\\theta_i$ (and insensitive\nto anisotropy). In addition to classical wetting (where holes in a film heal)\nand dewetting (where holes in a film grow), we observe cases where a hole\nthrough the film heals but leave a finite size hole/bubble between the\ncontinuous film and substrate or where the hole heals leaving a continuous film\nthat is not bonded to the substrate. Surface energy anisotropy (i) increases\nthe instability that leads to island break-up into multiple islands, (ii)\nenhances hole healing, and (iii) leads to finite island size even under some\nconditions where the Young's angle $\\theta_i$ suggests that the film wets the\nsubstrate.",
        "positive": "Spatial Correlation at the Boson Peak Frequency in Amorphous Materials: The Boson peak (BP), an excess of vibrational density of states, is\nubiquitous for amorphous materials and is believed to hold the key to\nunderstanding the dynamics of glass and glass transition. Previous studies have\nestablished an energy scale for the BP, which is ~1-10 meV or ~THz in\nfrequency. However, so far, little is known about the momentum dependence or\nspatial correlation of the BP. Here, we report the observation of the BP in\nmodel Zr-Cu-Al metallic glasses over a wide range of momentum transfer, using\ninelastic neutron scattering, heat capacity, Raman scattering measurements, and\nmolecular dynamics (MD) simulations. The BP energy is largely dispersionless;\nhowever, the BP intensity was found to scale with the static structure factor.\nAdditional MD simulations with a generic Lennard-Jones potential confirmed the\nsame. Based on these results, an analytical expression for the dynamic\nstructure factor was formulated for the BP excitation. Further analysis of the\nsimulated disordered structures suggests that the BP is related to local\nstructure fluctuations (e.g., in shear strain). Our results offered insights\ninto the nature of the BP and provide guidance for the development of theories\nof amorphous materials."
    },
    {
        "anchor": "Electronic Structure of Single-Walled Carbon Nanotubes Governed by\n  Odd-Electrons Interaction: For the first time, an approach is suggested for the quantitative description\nof the electronic structure of single-walled carbon nanotubes and the\nprediction of active sites for the tube controlled functionalization in view of\nthe tube length and ends structure. The approach is based on the tube\ncharacteristic feature connected with odd electrons and is illustrated for a\nfamily involving fragments of arm-chair configured (4,4) single-walled\nnanotubes differing by length and end structure. Short and long tubes as well\nas tubes with cap end and open end, in the latter case, both hydrogen\nterminated and empty, are considered. Algorithms of the quantitative\ndescription of the tubes of any length are suggested. Calculations were\nperformed in the framework of the single-determinant unrestricted Hartree-Fock\napproach.",
        "positive": "On the significance of asperity models predictions of rough contact with\n  respect to recent alternative theories: Recently, it has been shown that while asperity models show correctly\nqualitative features of rough contact problems (linearity in area-load,\nnegative exponential dependence of load on separation which means also\nlinearity of stiffness with load), the exact value of the coefficients are not\nprecise for the idealized case of Gaussian distribution of heigths. This is due\nto the intrinsic simplifications, neglecting asperity coalescence and\ninteraction effects. However, the issue of Gaussianity has not been proved or\nexperimentally verified in many cases, and here we show that, for example,\nassuming a Weibull distribution of asperity heigths, the area-load linear\ncoefficient is not much affected, while the relationships load-separation and\ntherefore also stiffness-load do change largely, particularly when considering\nbounded distributions of asperity heigths. It is suggested that Gaussianity of\nsurfaces should be further tested in experiments, before applying the most\nsophisticated rough contact models based on the Gaussian assumption."
    },
    {
        "anchor": "Thermoelectric properties of Topological Weyl Semimetal Cu$_2$ZnGeTe$_4$: The study of topological quantum materials for enhanced thermoelectric energy\nconversion has received significant attention recently. Topological materials\n(including topological insulators and Dirac/Weyl/nodal-line semi-metals) with\nunique nature of band structure involving linear and regular parabolic bands\nnear Fermi level (E$_F$) have the potential to show promising TE properties. In\nthis article, we report the promising TE performance of a quaternary\nchalcogenide (Cu$_2$ZnGeTe$_4$) having non-trivial topological phase. At\nambient condition, the compound is a narrow band gap (0.067 eV) semiconductor,\nwith a TE figure of merit (ZT) 1.2. Application of 5% strain drives the system\nto a topologically non-trivial Weyl semi-metal with the right combination of\nlinear and parabolic bands near E$_F$, giving rise to a reasonable ZT of 0.36.\nApart from strain, alloy engineering (Sn substituted at Ge) is also shown to\ninduce topological non-triviality. The present work demonstrates the potential\nof such unique semimetals for exceptional electronic transport properties and\nhence excellent thermoelectric performance.",
        "positive": "Quadratic contact point semimetal: Theory and material realization: Most electronic properties of metals are determined solely by the low-energy\nstates around the Fermi level, and for topological metals/semimetals, these\nlow-energy states become distinct because of their unusual energy dispersion\nand emergent pseudospin degree of freedom. Here, we propose a class of\nmaterials which are termed as quadratic contact point (QCP) semimetals. In\nthese materials, the conduction and valence bands contact at isolated points in\nthe Brillouin zone, around which the band dispersions are quadratic along all\nthree directions. We show that in the absence/presence of spin-orbit coupling,\nthere may exist triply/quadruply-degenerate QCPs that are protected by the\ncrystalline symmetry. We construct effective models to characterize the\nlow-energy fermions near these QCPs. Under strong magnetic field, unlike the\nusual 3D electron gas, there appear unconventional features in the Landau\nspectrum. The QCP semimetal phase is adjacent to a variety of topological\nphases. For example, by breaking symmetries via Zeeman field or lattice strain,\nit can be transformed into a Weyl semimetal with Weyl and double Weyl points, a\nZ2 topological insulator/metal, or a Dirac semimetal. Via first-principles\ncalculations, we identify realistic materials Cu2Se and RhAs3 as candidates for\nQCP semimetals."
    },
    {
        "anchor": "Ferromagnetic order of ultra-thin La0.7Ba0.3MnO3 sandwiched between\n  SrRuO3 layers: We demonstrate the stability of ferromagnetic order of one unit cell thick\noptimally doped manganite (La0.7Ba0.3MnO3, LBMO) epitaxially grown between two\nlayers of SrRuO3 (SRO) by using x-ray magnetic circular dichroism. At low\ntemperature LBMO shows an inverted hysteresis loop due to the strong\nantiferromagnetic coupling to SRO. Moreover, above SRO TC the manganite still\nexhibits magnetic remanence. Density Functional Theory calculations show that\ncoherent interfaces of LBMO with SRO hinder electronic confinement and the\nstrong magnetic coupling enables the increase of the LBMO TC. From the\nstructural point of view, interfacing with SRO enables LBMO to have octahedral\nrotations similar to bulk. All these factors jointly contribute for stable\nferromagnetism up to 130 K for a one unit cell LBMO film.",
        "positive": "FP-LMTO studies of hypothetical compounds with the beta$-SiAlON-like\n  structure in Si--(Mg,Al)--O--N systems: The electronic and energy properties of beta-Si3N4 (a), Si{6-x}AlxOxN{8-x}\n(b) and the hypothetical ordered solid solutions Si{6-x}MgxO{2x}N{8-2x} (c),\nSi{6-x}MgxOxN{8-2x}Sx (d), Si{6-x}MgxOxN{8-x} (e),\nSi{6-x}Mg{x/2}Al{x/2}OxN{8-x} (f) are considered by the ab-initio band FP-LMTO\nmethod. The calculations show that the stability of the systems decreases in\nthe order: (a) > (b) > (f) > (e) > (c) > (d). It is established that\nSi{6-x}MgxOxN{8-x} and Si{6-x}Mg{x/2}Al{x/2}OxN{8-x} possess non-zero values of\nthe density of states at the Fermi energy, which consists mainly of localized\nO2p, N2p states, and the conductivity in those solid solutions is unlikely. It\nis found that the energy of the O2s,p states tends to shift depending on the\ncoordination environment of oxygen atoms in the considered systems. The energy\nof ordering of Al and Mg atoms in Si{6-x}Mg{x/2}Al{x/2}OxN{8-x} is estimated to\nbe 3.15 eV/56-atomic supercell."
    },
    {
        "anchor": "Optical properties of perovskite alkaline earth titanates : a\n  formulation: In this communication we suggest a formulation of the optical conductivity as\na convolution of an energy resolved joint density of states and an\nenergy-frequency labelled transition rate. Our final aim is to develop a scheme\nbased on the augmented space recursion for random systems. In order to gain\nconfidence in our formulation, we apply the formulation to three alkaline earth\ntitanates CaTiO_3, SrTiO_3 and BaTiO_3 and compare our results with available\ndata on optical properties of these systems.",
        "positive": "Spin Hall Effect in a Diffusive Rashba Two-dimensional Electron Gas: A nonequilibrium Green's functions approach to spin-Hall effect is developed\nin a diffusive two-dimensional electron system with Rashba spin-orbit\ninteraction. In the presence of long-range impurities, the coupled quantum\nkinetic equations are solved analytically in the self-consistent Born\napproximation. It is shown that the intrinsic spin-Hall effect stems from the\ndc-field-induced perturbation of the density of states. In addition, there is\nan additional disorder-mediated process, which involves the transition of\nnonequilibrium electrons between two spin-orbit-coupled bands. It results in an\nadditional collision-independent spin-Hall conductivity and leads to the\nvanishing of the total spin-Hall current even at nonzero temperature."
    },
    {
        "anchor": "CW and pulsed electrically detected magnetic resonance spectroscopy at\n  263 GHz/12 T on operating amorphous silicon solar cells: Here we describe a new high frequency/high field continuous wave and pulsed\nelectrically detected magnetic resonance (CW EDMR and pEDMR) setup, operating\nat 263 GHz and resonance fields between 0 and 12 T. Spin dependent transport in\nilluminated hydrogenated amorphous silicon p-i-n solar cells at 5 K and 90 K\nwas studied by in operando 263 GHz CW and pEDMR alongside with complementary\nX-band CW EDMR. Benefiting from the superior resolution at 263 GHz, we were\nable to better resolve EDMR signals originating from spin dependent hopping and\nrecombination processes. 5 K EDMR spectra were found to be dominated by\nconduction and valence band tale states involved in spin dependent hopping,\nwith additional contributions from triplet exciton states. 90 K EDMR spectra\ncould be assigned to spin pair recombination involving conduction band tail\nstates and dangling bonds as dominating spin dependent transport process, with\nadditional contributions from valence band tail and triplet exciton states.",
        "positive": "Effects of solute concentrations on kinetic pathways in Ni-Al-Cr alloys: The kinetic pathways resulting from the formation of coherent L12-ordered\ny'-precipitates in the g-matrix (f.c.c.) of Ni-7.5 Al-8.5 Cr at.% and Ni-5.2\nAl-14.2 Cr at.% alloys, aged at 873 K, are investigated by atom-probe\ntomography (APT) over a range of aging times from 1/6 to 1024 hours; these\nalloys have approximately the same volume fraction of the y'-precipitate phase.\nQuantification of the phase decomposition within the framework of classical\nnucleation theory reveals that the y-matrix solid-solution solute\nsupersaturations of both alloys provide the chemical driving force, which acts\nas the primary determinant of the nucleation behavior. In the coarsening\nregime, the temporal evolution of the y'-precipitate average radii and the\ny-matrix supersaturations follow the predictions of classical coarsening\nmodels, while the temporal evolution of the y'-precipitate number densities of\nboth alloys do not. APT results are compared to equilibrium calculations of the\npertinent solvus lines determined by employing both Thermo-Calc and\nGrand-Canonical Monte Carlo simulation."
    },
    {
        "anchor": "Ab initio study of beryllium-decorated fullerenes for hydrogen storage: We have found that a beryllium (Be) atom on nanostructured materials with H2\nmolecules generates a Kubas-like dihydrogen complex [H. Lee et al.\narXiv:1002.2247v1 (2010)]. Here, we investigate the feasibility of Be-decorated\nfullerenes for hydrogen storage using ab initio calculations. We find that the\naggregation of Be atoms on pristine fullerenes is energetically preferred,\nresulting in the dissociation of the dihydrogen. In contrast, for boron\n(B)-doped fullerenes, Be atoms prefer to be individually attached to B sites of\nthe fullerenes, and a maximum of one H2 molecule binds to each Be atom in a\nform of dihydrogen with a binding energy of ~0.3 eV. Our results show that\nindividual dispersed Be-decorated B-doped fullerenes can serve as a\nroom-temperature hydrogen storage medium.",
        "positive": "Subamorphous thermal conductivity of crystalline half-Heusler\n  superlattices: The quest to improve the thermoelectric figure of merit has mainly followed\nthe roadmap of lowering the thermal conductivity while keeping unaltered the\npower factor of the material. Ideally an electron-crystal phonon-glass system\nis desired. In this work, we report an extraordinary reduction of the\ncross-plane thermal conductivity in crystalline (TiNiSn):(HfNiSn) half-Heusler\nsuperlattices. We create SLs with thermal conductivities below the effective\namorphous limit, which is kept in a large temperature range (120-300 K). We\nmeasured thermal conductivity at room temperature values as low as 0.75 W/(m\nK), the lowest thermal conductivity value reported so far for half-Heusler\ncompounds. By changing the deposition conditions, we also demonstrate that the\nthermal conductivity is highly impacted by the way the single segments of the\nsuperlattice grow. These findings show a huge potential for thermoelectric\ngenerators where an extraordinary reduction of the thermal conductivity is\nrequired but without losing the crystal quality of the system."
    },
    {
        "anchor": "Acoustic damping and dispersion in vitreous germanium oxide: New Brillouin scattering measurements of velocity and attenuation of sound in\nthe hypersonic regime are presented. The data are analyzed together with the\nliterature results at sonic and ultrasonic frequencies. As usual, thermally\nactivated relaxation of structural entities describes the attenuation at sonic\nand ultrasonic frequencies. As already shown in vitreous silica, we conclude\nthat the damping by network viscosity, resulting from relaxation of thermal\nphonons, must be taken into account to describe the attenuation at hypersonic\nfrequencies. In addition, the bare velocity obtained by subtracting to the\nexperimental data the effect of the two above mechanisms is constant for\ntemperatures below 250 K, but increases almost linearly above, up to the glass\ntransition temperature. This might indicate the presence of a progressive local\npolyamorphic transition, as already suggested for vitreous silica.",
        "positive": "Direct observation of size scaling and elastic interaction between\n  nano-scale defects in collision cascades: Using in-situ transmission electron microscopy, we have directly observed\nnano-scale defects formed in ultra-high purity tungsten by low-dose high energy\nself-ion irradiation at 30K. At cryogenic temperature lattice defects have\nreduced mobility, so these microscope observations offer a window on the\ninitial, primary damage caused by individual collision cascade events. Electron\nmicroscope images provide direct evidence for a power-law size distribution of\nnano-scale defects formed in high-energy cascades, with an upper size limit\nindependent of the incident ion energy, as predicted by Sand et al. [Eur. Phys.\nLett., 103:46003, (2013)]. Furthermore, the analysis of pair distribution\nfunctions of defects observed in the micrographs shows significant\nintra-cascade spatial correlations consistent with strong elastic interaction\nbetween the defects."
    },
    {
        "anchor": "Dilute Rhenium Doping and its Impact on Intrinsic Defects in MoS2: Substitutionally-doped 2D transition metal dichalcogenides are primed for\nnext-generation device applications such as field effect transistors (FET),\nsensors, and optoelectronic circuits. In this work, we demonstrate\nsubstitutional Rhenium (Re) doping of MoS2 monolayers with controllable\nconcentrations down to 500 parts-per-million (ppm) by metal-organic chemical\nvapor deposition (MOCVD). Surprisingly, we discover that even trace amounts of\nRe lead to a reduction in sulfur site defect density by 5-10x. Ab initio models\nindicate the free-energy of sulfur-vacancy formation is increased along the\nMoS2 growth-front when Re is introduced, resulting in an improved\nstoichiometry. Remarkably, defect photoluminescence (PL) commonly seen in\nas-grown MOCVD MoS2 is suppressed by 6x at 0.05 atomic percent (at.%) Re and\ncompletely quenched with 1 at.% Re. Furthermore, Re-MoS2 transistors exhibit up\nto 8x higher drain current and enhanced mobility compared to undoped MoS2\nbecause of the improved material quality. This work provides important insights\non how dopants affect 2D semiconductor growth dynamics, which can lead to\nimproved crystal quality and device performance.",
        "positive": "Electronic and optical properties of Mn impurities in ultra-thin ZnO\n  nanowires: insights from density-functional theory: In this work we have employed density-functional theory with hybrid\nfunctionals to investigate the atomic and electronic structure of bare and\nhydrogenated Mn doped ZnO nanowires with small diameter. We determine changes\nin magnetic and electronic structure of Mn-doped ZnO nanowires due to surface\neffects, such as hydrogen adsorption on the surface, presence of oxygen\nvacancies and dangling bonds. In the absence of passivation on the nanowire\nsurface, the manganese atoms segregate to the surface, whereas under hydrogen\nadsorption the incorporation of Mn is energetically more favourable at inner\nsites. The presence of additional oxygen vacancies does not produce signficant\nchanges in magnetic moments, although it produce significant changes in charge\nlocalization."
    },
    {
        "anchor": "Thermally activated magnetization reversal in bulk BiFe0.5Mn0.5O3: We report on the synthesis and characterization of BiFe0.5Mn0.5O3, a\npotential type-I multiferroic compound displaying temperature induced\nmagnetization reversal. Bulk samples were obtained by means of solid state\nreaction carried out under the application of hydrostatic pressure at 6 GPa and\n1100{\\deg}C. The crystal structure is an highly distorted perovskite with no\ncation order on the B site, where, besides a complex scheme of tilt and\nrotations of the TM-O6 octahedra, large off-centering of the bismuth ions is\ndetected. Below T1 = 420 K the compound undergoes a first weak ferromagnetic\ntransition related to the ordering of iron rich clusters. At lower temperatures\n(just below RT) two distinct thermally activated mechanisms are superimposed,\ninducing at first an enhancement of the magnetization at T2 = 288 K, then a\nspontaneous reversal process centered at T3 = 250 K, finally giving rise to a\nnegative response. The application of fields higher than 1500 Oe suppresses the\nprocess, yielding a ferromagnetic like behaviour. The complementary use of\nSQuID magnetometry and M\\\"ossbauer spectroscopy allowed the interpretation of\nthe overall magnetic behaviour in terms of an uncompensated weak competitive\ncoupling between non-equivalent clusters of interactions characterized by\ndifferent critical temperatures and resultant magnetizations. PACS numbers:\n75.85.+t, 75.60.Jk, 76.80.+y, 75.30.Et, 75.30.Kz",
        "positive": "Generalized estimates for the density of oxide scale in the range from 0\n  C to 1300 C: Oxide scale formed on the surface of steel products during high-teperature\nprocesses is studied as a composite material, the main solid components of\nwhich, in general, are wustite, magnetite, hematite and metallic iron. To\nestimate the density of each of these components in the temperature range from\n0 C to 1300 C, formulas are proposed that are consistent with the empirical\nfunctions of the coefficient of linear thermal expansion, which the authors\nobtained earlier by generaizing data from open sources. The Curie and\npolymorphic transformation temperatures are included in these generalized\nformulas as variable parameters, which allows one to take into account the\nmovability of phase transitions due to impurities, crystal lattice defects,\nparticle sizes, cooling rate, and other factors. When specifying the particular\nvalues of critical temperatures, the other parameters of the formulas are\nrecalculated automatically. In a particular form, the proposed formulas\ncorrespond to the basic values of critical temperatures. According to the\ncalculation examples given, the true (not including pores) density of oxide\nscale can be about 5200 to 5600 kg/m3, depending on the temperature and\npercentage of components, whereby a local density minimum may be observed in\nthe region of 570 C due to eutectoid decomposition of wustite into magnetite\nand iron. The proposed methods are recommended for use in mathematical\nsimulation of processing of steel products in the presence of oxide scale on\nits surface."
    },
    {
        "anchor": "Laplacian-level meta-generalized gradient approximation for solid and\n  liquid metals: We derive and motivate a Laplacian-level, orbital-free\nmeta-generalized-gradient approximation (LL-MGGA) for the exchange-correlation\nenergy, targeting accurate ground-state properties of $sp$ and $sd$ metallic\ncondensed matter, in which the density functional for the exchange-correlation\nenergy is only weakly nonlocal due to perfect long-range screening. Our model\nfor the orbital-free kinetic energy density restores the fourth-order gradient\nexpansion for exchange to the r$^2$SCAN meta-GGA [Furness et al., J. Phys.\nChem. Lett. 11, 8208 (2020)], yielding a LL-MGGA we call OFR2. OFR2 matches the\naccuracy of SCAN for prediction of common lattice constants and improves the\nequilibrium properties of alkali metals, transition metals, and intermetallics\nthat were degraded relative to the PBE GGA values by both SCAN and r$^2$SCAN.\nWe compare OFR2 to the r$^2$SCAN-L LL-MGGA [D. Mejia-Rodriguez and S.B.\nTrickey, Phys. Rev. B 102, 121109 (2020)] and show that OFR2 tends to\noutperform r$^2$SCAN-L for the equilibrium properties of solids, but\nr$^2$SCAN-L much better describes the atomization energies of molecules than\nOFR2 does. For best accuracy in molecules and non-metallic condensed matter, we\ncontinue to recommend SCAN and r$^2$SCAN. Numerical performance is discussed in\ndetail, and our work provides an outlook to machine learning.",
        "positive": "Electronic structures of iMAX phases and their two-dimensional\n  derivatives: A family of piezoelectric materials: Recently, a group of MAX phases, (Mo$_{2/3}$Y$_{1/3}$)$_2$AlC,\n(Mo$_{2/3}$Sc$_{1/3}$)$_2$AlC, (W$_{2/3}$Sc$_{1/3}$)$_2$AlC,\n(W$_{2/3}$Y$_{1/3}$)$_2$AlC, and (V$_{2/3}$Zr$_{1/3}$)$_2$AlC, with in-plane\nordered double transition metals, named iMAX phases, have been synthesized.\nExperimentally, some of these MAX phases can be chemically exfoliated into\ntwo-dimensional (2D) single- or multilayered transition metal carbides,\nso-called MXenes. Accordingly, the 2D nanostructures derived from iMAX phases\nare named iMXenes. Here, we investigate the structural stabilities and\nelectronic structures of the experimentally discovered iMAX phases and their\npossible iMXene derivatives. We show that the iMAX phases and their pristine,\nF, or OH-terminated iMXenes are metallic. However, upon O termination,\n(Mo$_{2/3}$Y$_{1/3}$)$_2$C, (Mo$_{2/3}$Sc$_{1/3}$)$_2$C,\n(W$_{2/3}$Y$_{1/3}$)$_2$C, and (W$_{2/3}$Sc$_{1/3}$)$_2$C iMXenes turn into\nsemiconductors. Owing to the absence of centrosymmetry, the semiconducting\niMXenes may find applications in piezoelectricity. Our calculations reveal that\nthe semiconducting iMXenes possess giant piezoelectric coefficients as large as\n45$\\times10^{-10}$~C/m."
    },
    {
        "anchor": "Mechanics of micropillar confined thin film plasticity: Micropillar compression experiments probing size effects in confined\nplasticity of metal thin films, including the indirect imposition of\n'canonical' simple shearing boundary conditions, show dramatically different\nresponses in compression and shear of the film. The Mesoscale Field Dislocation\nMechanics (MFDM) model is confronted with this set of experimental observations\nand shown to be capable of modeling such behavior, without any ad-hoc\nmodification to the basic structure of the theory (including boundary\nconditions), or the use of extra fitting parameters. This is a required\ntheoretical advance in the current state-of-the art of strain gradient\nplasticity models. It is also shown that significantly different inhomogeneous\nfields can display qualitatively similar size effect trends in overall\nagreement with the experimental results. The (plastic) Swift and (elastic)\nPoynting finite deformation effects are also demonstrated.",
        "positive": "Oxidation States of Graphene: Insights from Computational Spectroscopy: When it is oxidized, graphite can be easily exfoliated forming graphene oxide\n(GO). GO is a critical intermediate for massive production of graphene, and it\nis also an important material with various application potentials. With many\ndifferent oxidation species randomly distributed on the basal plane, GO has a\ncomplicated nonstoichiometric atomic structure that is still not well\nunderstood in spite of of intensive studies involving many experimental\ntechniques. Controversies often exist in experimental data interpretation. We\nreport here a first principles study on binding energy of carbon 1s orbital in\nGO. The calculated results can be well used to interpret experimental X-ray\nphotoelectron spectroscopy (XPS) data and provide a unified spectral\nassignment. Based on the first principles understanding of XPS, a GO structure\nmodel containing new oxidation species epoxy pair and epoxy-hydroxy pair is\nproposed. Our results demonstrate that first principles computational\nspectroscopy provides a powerful means to investigate GO structure."
    },
    {
        "anchor": "Pressure-induced excitations in the out-of-plane optical response of the\n  nodal-line semimetal ZrSiS: The anisotropic optical response of the layered, nodal-line semimetal ZrSiS\nat ambient and high pressure is investigated by frequency-dependent\nreflectivity measurements for the polarization along and perpendicular to the\nlayers. The highly anisotropic optical conductivity is in very good agreement\nwith results from density functional theory calculations and confirms the\nanisotropic character of ZrSiS. Whereas the in-plane optical conductivity shows\nonly modest pressure-induced changes, we found strong effects on the\nout-of-plane optical conductivity spectrum of ZrSiS, with the appearance of two\nprominent excitations. These pronounced pressure-induced effects can neither be\nattributed to a structural phase transition according to our single-crystal\nx-ray diffraction measurements, nor can they be explained by electronic\ncorrelation and electron-hole pairing effects, as revealed by theoretical\ncalculations. Our findings are discussed in the context of the recently\nproposed excitonic insulator phase in ZrSiS.",
        "positive": "Fabrication of High Quality QC Films via the Route of the Amorphous\n  Phase: We discuss the preparation of thin icosahedral films (Al-Cu-Fe and Al-Pd-Re)\nvia the route of the amorphous (a-)phase which in some aspects is a precursor\nto the icosahedral phase. A direct transition from the a- to the i-phase occurs\nfor Al-Cu-Fe films at 430 C on the time scale of minutes. The resulting films\nare of good quality as shown by diffraction and electronic transport\nproperties. The surface of the resulting films is very smooth."
    },
    {
        "anchor": "Pressure dependence of the monoclinic phase in\n  (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 solid solutions: We combine high-pressure x-ray diffraction, high-pressure Raman scattering,\nand optical microscope to investigate a series of PMN-xPT solid solutions\n(x=0.2, 0.3, 0.33, 0.35, 0.37, 0.4) in diamond anvil cells up to 20 GPa at 300\nK. The Raman spectra show a peak centered at 380 cm-1 above 6 GPa for all\nsamples, in agreement with previous observations. X-ray diffraction\nmeasurements are consistent with this spectral change indicating structural\nphase transition; we find that the triplet at the pseudo cubic (220) Bragg peak\nmerges into a doublet above 6 GPa. Our results indicate that the morphotropic\nphase boundary region (x=0.33 to 0.37) with the presence of monoclinic symmetry\npersists up to 7 GPa. The pressure dependence of ferroelectric domains in\nPMN-0.32PT single crystals was observed using a polarizing optical microscope.\nThe domain wall density decreases with pressure and domains disappear at a\nmodest pressure of 3 GPa. We propose a pressure-composition phase diagram for\nPMN-xPT solid solutions.",
        "positive": "Operando observation of reversible oxygen migration and phase\n  transitions in ferroelectric devices: Unconventional ferroelectricity, robust at reduced nanoscale sizes, exhibited\nby hafnia-based thin-films presents tremendous opportunities in\nnanoelectronics. However, the exact nature of polarization switching remains\ncontroversial. Here, we investigate epitaxial Hf0.5Zr0.5O2 (HZO) capacitors,\ninterfaced with oxygen conducting metals (La0.67Sr0.33MnO3, LSMO) as\nelectrodes, using atomic resolution electron microscopy while in situ\nelectrical biasing. By direct oxygen imaging, we observe reversible oxygen\nvacancy migration from the bottom to the top electrode through HZO and reveal\nassociated reversible structural phase transitions in the epitaxial LSMO and\nHZO layers. We follow the phase transition pathways at the atomic scale and\nidentify that these mechanisms are at play both in tunnel junctions and\nferroelectric capacitors switched with sub-millisecond pulses. Our results\nunmistakably demonstrate that oxygen voltammetry and polarization switching are\nintertwined in these materials."
    },
    {
        "anchor": "Symmetry-enforced Fermi degeneracy in topological semimetal RhSb$_3$: Predictions of a topological electronic structure in the skutterudite TPn$_3$\nfamily (T=transition metal, Pn=pnictogen) are investigated via\nmagnetoresistance, quantum oscillations and angle-resolved photoemission\nexperiments of RhSb$_3$, an unfilled skutterudite semimetal with low carrier\ndensity. Electronic band structure calculations and symmetry analysis of\nRhSb$_3$ indicate this material to be a zero-gap semimetal protected by\nsymmetry with inverted valence/conduction bands that touch at the $\\Gamma$\npoint close to the Fermi level. Transport experiments reveal an unsaturated\nlinear magnetoresistance that approaches a factor of 200 at 60~T magnetic\nfields, and quantum oscillations observable up to 150~K that are consistent\nwith a large Fermi velocity ($\\sim 1.3\\times 10^6$ m/s), high carrier mobility\n($\\sim 14$ m$^2$/Vs), and the existence of a small three dimensional hole\npocket. A very small, sample-dependent effective mass falls to values as low as\n$0.018(2)$ of the bare electron mass and scales with Fermi wavevector. This,\ntogether with a non-zero Berry's phase and location of the Fermi level in the\nlinear region of the valence band, suggests RhSb$_3$ as representative of a new\nclass of toplogical semimeals with symmetry-enforced Fermi degeneracy at the\nhigh symmetry points.",
        "positive": "Ab-initio investigation of the covalent bond energies in the metallic\n  covalent superconductor MgB2 and in AlB2: The contributions of the covalent bond energies of various atom pairs to the\ncohesive energy of MgB2 and AlB2 are analysed with a variant of our recently\ndeveloped energy-partitioning scheme for the density-functional total energy.\nThe covalent bond energies are strongest for the intralayer B-B pairs. In\ncontrast to the general belief, there is also a considerable covalent bonding\nbetween the layers, mediated by the metal atom. The bond energies between the\nvarious atom pairs are analysed in terms of orbital- and energy-resolved\ncontributions."
    },
    {
        "anchor": "Investigation of the phase separation property in\n  La$_{0.2}$Pr$_{0.4}$Ca$_{0.4}$MnO$_3$ manganite: We report a comprehensive investigation of La0.2Pr0.4Ca0.4MnO3 to clarify the\nmicrometre scale phase separation phenomenon in the mixed valent manganite\n(La,Pr,Ca)MnO3. The compound shows multiple magnetic transitions, in which the\ncharge-ordered state is converted into a ferromagnetic state in steps with the\napplication of a magnetic field. The ac susceptibility measurements show that\nthe glassy transition at low temperatures does not depend on the frequency,\nthus indicating the absence of any spin glass behaviour. Magnetization as well\nas heat capacity measurements indicate that this low temperature transition is\nmagnetic field dependent. The field dependent resistivity at 2K shows a sharp\ndrop indicating that the sample behaviour changes from a high resistive state\nto a low resistive state, corroborating the conversion of charge-ordered\ninsulating (COI) phase to a ferromagnetic metallic (FMM) phase. Our results\npoint towards the existence of phase separation, rigidity of the low\ntemperature glassy-like phase as well as the conversion of COI phase to FMM\nphase by the application of magnetic fields.",
        "positive": "Magnetoelectric fields for microwave chirality discrimination in\n  enantiomeric liquids: Chirality discrimination is of a fundamental interest in biology, chemistry,\nand metamaterial studies. In optics, near-field plasmon-resonance spectroscopy\nwith superchiral probing fields is effectively applicable for analyses of large\nbiomolecules with chiral properties. We show possibility for microwave\nnear-field chirality discrimination analysis based on magnon-resonance\nspectroscopy. Newly developed capabilities in microwave sensing using\nmagnetoelectric (ME) probing fields originated from multiresonance\nmagnetic-dipolar-mode (MDM) oscillations in quasi-2D yttrium-iron-garnet (YIG)\ndisks, provide a potential for unprecedented measurements of chemical and\nbiological objects. We report on microwave near-field chirality discrimination\nfor aqueous D- and L-glucose solutions. The shown ME-field sensing is addressed\nto microwave biomedical diagnostics and pathogen detection and to deepening our\nunderstanding of microwave-biosystem interactions. It can be also important for\nan analysis and design of microwave chiral metamaterials."
    },
    {
        "anchor": "Boundary Lubrication: Squeeze-out Dynamics of a Compressible 2D Liquid: The expulsion dynamics of the last liquid monolayer of molecules confined\nbetween two surfaces has been analyzed by solving the two-dimensional (2D)\nNavier-Stokes equation for a compressible liquid. We find that the squeeze-out\nis characterized by the parameter g0 ~ P0/(rho c^2), where P0 is the average\nperpendicular (squeezing) pressure, rho the liquid (3D) density and c the\nlongitudinal sound velocity in the monolayer film. When g0 << 1 the result of\nthe earlier incompressible treatment is recovered. Numerical results for the\nsqueeze-out time, and for the time-dependence of the radius of the squeezed-out\nregion, indicate that compressibility effects may be non-negligible both in\ntime and in space. In space, they dominate at the edge of the squeeze-out\nregion. In time, they are strongest right at the onset of the squeeze-out\nprocess, and just before its completion.",
        "positive": "Oscillatory and tip-splitting instabilities in 2D dynamic fracture: The\n  roles of intrinsic material length and time scales: Recent theoretical and computational progress has led to unprecedented\nunderstanding of symmetry-breaking instabilities in 2D dynamic fracture. At the\nheart of this progress resides the identification of two intrinsic, near crack\ntip length scales -- a nonlinear elastic length scale $\\ell$ and a dissipation\nlength scale $\\xi$ -- that do not exist in the classical theory of cracks. In\nparticular, it has been shown that at a high propagation velocity $v$, cracks\nin 2D brittle materials undergo an oscillatory instability whose wavelength\nvaries linearly with $\\ell$, and at yet higher propagation velocities and\nlarger loading levels, a tip-splitting instability emerges, both in agreements\nwith experiments. In this paper, using phase-field models of brittle fracture,\nwe demonstrate the following properties of the oscillatory instability: (i) It\nexists also in the absence of near-tip elastic nonlinearity, i.e. in the limit\n$\\ell\\!\\to\\!0$, with a wavelength determined by the dissipation length scale\n$\\xi$. This result shows that the instability crucially depends on the\nexistence of an intrinsic length scale associated with the breakdown of linear\nelasticity near crack tips, independently of whether the latter is related to\nnonlinear elasticity or to dissipation. (ii) It is a supercritical Hopf\nbifurcation, featuring a vanishing oscillations amplitude at onset. (iii) It is\nlargely independent of the fracture energy $\\Gamma(v)$ that is controlled by a\ndissipation time scale. These results substantiate the universal nature of the\noscillatory instability of ultra-high speed cracks in 2D. In addition, we\nprovide evidence indicating that the ultra-high velocity tip-splitting\ninstability is controlled by the limiting rate of elastic energy transport\ninside the crack tip region. Finally, we describe in detail the numerical\nimplementation scheme of the employed phase-field fracture approach."
    },
    {
        "anchor": "Ab initio lattice thermal conductivity of bulk and thin-film\n  $\u03b1$-Al$\\mathrm{_2}$O$\\mathrm{_3}$: The thermal conductivities ($\\kappa$) of bulk and thin-film\n$\\alpha$-Al$_2$O$_3$ are calculated from first principles using both the local\ndensity approximation (LDA), and the generalized gradient approximation (GGA)\nto exchange and correlation. The room temperature single crystal LDA value\n$\\sim39~$W/m$~$K agrees well with the experimental values $\\sim35-39~$W/m$~$K,\nwhereas the GGA values are much smaller $\\sim$26$~$W/m$~$K. Throughout the\ntemperature range, LDA is found to slightly overestimate $\\kappa$ whereas GGA\nstrongly underestimates it. We calculate the $\\kappa$ of crystalline\n$\\alpha$-Al$\\mathrm{_2}$O$\\mathrm{_3}$ thin films and observe a maximum of\n79$\\%$ reduction for $10~$nm thickness.",
        "positive": "Edge state on hydrogen-terminated graphite edges investigated by\n  scanning tunneling microscopy: The edge states that emerge at hydrogen-terminated zigzag edges embedded in\ndominant armchair edges of graphite are carefully investigated by\nultrahigh-vacuum scanning tunneling microscopy (STM) measurements. The edge\nstates at the zigzag edges have different spatial distributions dependent on\nthe $\\alpha$- or $\\beta$-site edge carbon atoms. In the case that the defects\nconsist of a short zigzag (or a short Klein) edge, the edge state is present\nalso near the defects. The amplitude of the edge state distributing around the\ndefects in an armchair edge often has a prominent hump in a direction\ndetermined by detailed local atomic structure of the edge. The tight binding\ncalculation based on the atomic arrangements observed by STM reproduces the\nobserved spatial distributions of the local density of states."
    },
    {
        "anchor": "General Relativity in Electrical Engineering: In electrical engineering metamaterials have been developed that offer\nunprecedented control over electromagnetic fields. Here we show that general\nrelativity lends the theoretical tools for designing devices made of such\nversatile materials. Given a desired device function, the theory describes the\nelectromagnetic properties that turn this function into fact. We consider media\nthat facilitate space-time transformations and include negative refraction. Our\ntheory unifies the concepts operating behind the scenes of perfect invisibility\ndevices, perfect lenses, the optical Aharonov-Bohm effect and electromagnetic\nanalogs of the event horizon, and may lead to further applications.",
        "positive": "Improved graphene blisters by ultrahigh pressure sealing: Graphene is a very attractive material for nanomechanical devices and\nmembrane applications. Graphene blisters based on silicon oxide micro-cavities\nare a simple but relevant example of nanoactuators. A drawback of this\nexperimental set up is that gas leakage through the graphene-SiO2 interface\ncontributes significantly to the total leak rate. Here we study the diffusion\nof air from pressurized graphene drumheads on SiO2 micro-cavities and propose a\nstraightforward method to improve the already strong adhesion between graphene\nand the underlying SiO2 substrate, resulting in reduced leak rates. This is\ncarried out by applying controlled and localized ultrahigh pressure (> 10 GPa)\nwith an Atomic Force Microscopy diamond tip. With this procedure, we are able\nto significantly approach the graphene layer to the SiO2 surface around the\ndrumheads, thus enhancing the interaction between them allowing us to better\nseal the graphene-SiO2 interface, which is reflected in up to ~ 4 times lower\nleakage rates. Our work opens an easy way to improve the performance of\ngraphene as a gas membrane on a technological relevant substrate such as SiO2."
    },
    {
        "anchor": "Is Cement a Glassy Material?: The nature of Calcium--Silicate--Hydrate (C--S--H), the binding phase of\ncement, remains a controversial question. In particular, contrary to the former\ncrystalline model, it was recently proposed that its nanoscale structure was\nactually amorphous. To elucidate this issue, we analyzed the structure of a\nrealistic simulation of C--S--H, and compared the latter to crystalline\ntobermorite, a natural analogue to cement, and to an artificial ideal glass.\nResults clearly support that C--S--H is amorphous. However, its structure shows\nan intermediate degree of order, retaining some characteristics of the crystal\nwhile acquiring an overall glass-like disorder. Thanks to a detailed\nquantification of order and disorder, we show that its amorphous state mainly\narises from its hydration.",
        "positive": "Coulombically-stabilized oxygen hole polarons enable fully reversible\n  oxygen redox: Stabilizing high-valent redox couples and exotic electronic states\nnecessitate an understanding of the stabilization mechanism. In oxides, whether\nthey are being considered for energy storage or computing, highly oxidized\noxide-anion species rehybridize to form short covalent bonds and are related to\nsignificant local structural distortions. In intercalation oxide electrodes for\nbatteries, while such reorganization partially stabilizes oxygen redox, it also\ngives rise to substantial hysteresis. In this work, we investigate oxygen redox\nin layered Na2-XMn3O7, a positive electrode material with ordered Mn vacancies.\nWe show that coulombic interactions between oxidized oxide-anions and the\ninterlayer Na vacancies can disfavor rehybridization and stabilize hole\npolarons on oxygen at 4.2 V vs. Na/Na+. These coulombic interactions provide\nthermodynamic energy saving as large as O-O covalent bonding and enable ~ 40 mV\nvoltage hysteresis over multiple electrochemical cycles with negligible voltage\nfade. Our results establish a complete picture of redox energetics by\nhighlighting the role of coulombic interactions across several atomic distances\nand suggest avenues to stabilize highly oxidized oxygen for applications in\nenergy storage and beyond."
    },
    {
        "anchor": "Ultra-high vacuum compatible preparation chain for intermetallic\n  compounds: We report the development of a versatile material preparation chain for\nintermetallic compounds that focuses on the realization of a high-purity growth\nenvironment. The preparation chain comprises of an argon glovebox, an\ninductively heated horizontal cold boat furnace, an arc melting furnace, an\ninductively heated rod casting furnace, an optically heated floating-zone\nfurnace, a resistively heated annealing furnace, and an inductively heated\nannealing furnace. The cold boat furnace and the arc melting furnace may be\nloaded from the glovebox by means of a load-lock permitting to synthesize\ncompounds starting with air-sensitive elements while handling the constituents\nexclusively in an inert gas atmosphere. All furnaces are all-metal sealed,\nbakeable, and may be pumped to ultra-high vacuum. We find that the latter\nrepresents an important prerequisite for handling compounds with high vapor\npressure under high-purity argon atmosphere. We illustrate operational aspects\nof the preparation chain in terms of the single-crystal growth of the\nheavy-fermion compound CeNi2Ge2.",
        "positive": "Experimental investigation of the local environment and lattice\n  distortion in refractory medium entropy alloys: EXAFS analysis of pure elements, binary and ternary equiatomic refractory\nalloys within the Nb-Zr-Ti-Hf-Ta system is performed at the Nb and Zr K-edges\nto analyze the evolution of the chemical local environment and the lattice\ndistortion. A good mixing of the elements is found at the atomic scale. For\nsome compounds, a distribution of distances between the central atom and its\nneighbors suggests a distortion of the structure. Finally, analysis of the\nDebye-Waller parameters show some correlation with the lattice distortion\nparameter $\\delta ^2$, and allows to quantify experimentally the static\ndisorder in medium entropy alloys."
    },
    {
        "anchor": "Transport Spin Polarization of High-Curie Temperature MnBi Films: We report on the study of the structural, magnetic and transport properties\nof highly textured MnBi films with the Curie temperature of 628K. In addition\nto detailed measurements of resistivity and magnetization, we measure transport\nspin polarization of MnBi by Andreev reflection spectroscopy and perform fully\nrelativistic band structure calculations of MnBi. A spin polarization from\n51\\pm1 to 63\\pm1% is observed, consistent with the calculations and with an\nobservation of a large magnetoresistance in MnBi contacts. The band structure\ncalculations indicate that, in spite of almost identical densities of states at\nthe Fermi energy, the large disparity in the Fermi velocities leads to high\ntransport spin polarization of MnBi. The correlation between the values of\nmagnetization and spin polarization is discussed.",
        "positive": "How do the grains slide in fine-grained zirconia polycrystals at high\n  temperature?: Degradation of mechanical properties of zirconia polycrystals is hardly\ndiscussed in terms of solution-precipitation grain-boundary sliding due to\nexperimental controversies over imaging of intergranular amorphous phases at\nhigh and room temperatures. Here, the authors applied the techniques of\nmechanical spectroscopy and transmission electron microscopy (TEM) to shed\nlight on the amorphization of grain interfaces at high temperature where the\ninterface-reaction determines the behaviour of fine-grained zirconia\npolycrystals. They present mechanical spectroscopy results, which yield\nevidences of an intergranular amorphous phase in silica doped and high-purity\nzirconia at high temperature. Quenching of zirconia polycrystals reveals an\nintergranular amorphous phase on TEM images at room temperature."
    },
    {
        "anchor": "Photo-induced semimetallic states realised in electron-hole coupled\n  insulators: Using light to manipulate materials into desired states is one of the goals\nin condensed matter physics, since light control can provide ultrafast and\nenvironmentally-friendly photonics devices. However, it is generally difficult\nto realise a photo-induced phase which is not merely a higher entropy phase\ncorresponding to a high-temperature phase at equilibrium. Here, we report\nrealization of photo-induced insulator-to-metal transitions in Ta2Ni(Se1-xSx)5\nincluding the excitonic insulator phase using time- and angle-resolved\nphotoemission spectroscopy. From the dynamic properties of the system, we\ndetermine that screening of excitonic correlations plays a key role in the\ntimescale of the transition to the metallic phase, which supports the existence\nof an excitonic-insulator phase at equilibrium. The non-equilibrium metallic\nstate observed unexpectedly in the direct-gap excitonic insulator opens up a\nnew avenue to optical band engineering in electron-hole coupled systems.",
        "positive": "Localization landscape theory of disorder in semiconductors. III.\n  Application to carrier transport and recombination in light emitting diodes: This paper introduces a novel method to account for quantum disorder effects\ninto the classical drift-diffusion model of semiconductor transport through the\nlocalization landscape theory. Quantum confinement and quantum tunneling in the\ndisordered system change dramatically the energy barriers acting on the\nperpendicular transport of heterostructures. In addition they lead to\npercolative transport through paths of minimal energy in the 2D landscape of\ndisordered energies of multiple 2D quantum wells. This model solves the carrier\ndynamics with quantum effects self-consistently and provides a computationally\nmuch faster solver when compared with the Schr\\\"odinger equation resolution.\nThe theory also provides a good approximation to the density of states for the\ndisordered system over the full range of energies required to account for\ntransport at room-temperature. The current-voltage characteristics modeled by\n3-D simulation of a full nitride-based light-emitting diode (LED) structure\nwith compositional material fluctuations closely match the experimental\nbehavior of high quality blue LEDs. The model allows also a fine analysis of\nthe quantum effects involved in carrier transport through such complex\nheterostructures. Finally, details of carrier population and recombination in\nthe different quantum wells are given."
    },
    {
        "anchor": "First-principles calculation of electronic excitations in solids with\n  SPEX: We describe the software package SPEX, which allows first-principles\ncalculations of quasiparticle and collective electronic excitations in solids\nusing techniques from many-body perturbation theory. The implementation is\nbased on the full-potential linearized augmented-plane-wave (FLAPW) method,\nwhich treats core and valence electrons on an equal footing and can be applied\nto a wide range of materials, including transition metals and rare earths.\nAfter a discussion of essential features that contribute to the high numerical\nefficiency of the code, we present illustrative results for quasiparticle band\nstructures calculated within the GW approximation for the electronic\nself-energy, electron-energy-loss spectra with inter- and intraband transitions\nas well as local-field effects, and spin-wave spectra of itinerant\nferromagnets. In all cases the inclusion of many-body correlation terms leads\nto very good quantitative agreement with experimental spectroscopies.",
        "positive": "Soft Modes and Local Structural Transitions in Pb-free\n  Ba(Ti0.8Zr0.2)O3-x(Ba0.7Ca0.3)TiO3 (x = 0.5): Pressure- and\n  Temperature-dependent Raman Studies: We report our Raman studies of a new lead-free relaxor ferroelectrics,\nBa0.85Ca0.15Ti0.9Zr0.1O3 (BCTZO). The Raman modes of BCTZO are compared with\nthose of BaTi0.8Zr0.2O3 (BTZO), and BaTiO3 (BTO). Also, they are compared with\nthe eigenmodes of BTO calculated by using an ab-initio quantum-mechanical\nfrozen-phonon method. The sharp mode at 321 cm-1 of BTO, reported as a coupled\nmode showing an interference effect, becomes progressively broader in BTZO and\nBCTZO. This behavior, together with a broadening of the 527-cm-1 mode, suggests\nthat the mode-coupling is weakened in BTZO and BCTZO. The structural\ntransitions of BCTZO were investigated as functions of pressure at pressures\nbelow 20 GPa and of temperature at temperatures below 600 K. Three\ncharacteristic pressure-induced transitions, on each at 2.5, 5.0, and 13.0 GPa,\nwere found. The transitions are suggested by the drastic changes in phonon\nmodes (two softening modes, one each at ~ 300 and ~ 530 cm-1) and by the\ntransformation of the intensity profile. A temperature-induced transition was\nfound at a Curie temperature of ~ 380 K, where the average structure changes\nfrom tetragonal to cubic. It is accompanied by a softening mode at ~ 530 cm-1.\nThe phonon spectrum of BCTZO suggests that its local environment is close to\nthat of BTZO. However, the characteristic pressures of BCTZO are close to those\nof BTO. The sequence of pressure-induced transitions in both BCTZO and BTZO\nillustrate rich interplay between the long-range averaged structure and the\nshort-range local order such that four distinguishable phases are suggested:\ntetragonal, locally ordered but compensated cubic, disordered cubic, and ideal\ncubic. We found that the critical pressures are plausibly related to the\naverage crystal lattice."
    },
    {
        "anchor": "Mobility in Graphene Double Gate Field Effect Transistors: In this work, double-gated field effect transistors manufactured from\nmonolayer graphene are investigated. Conventional top-down CMOS-compatible\nprocesses are applied except for graphene deposition by manual exfoliation.\nCarrier mobilities in single- and double gated graphene field effect\ntransistors are compared. Even in double-gated graphene FETs, the carrier\nmobility exceeds the universal mobility of silicon over nearly the entire\nmeasured range. At comparable dimensions, reported mobilities for ultra thin\nbody silicon-on-insulator MOSFETs can not compete with graphene FET values.",
        "positive": "Critical resolved shear stresses for slip and twinning in Mg-Y-Ca alloys\n  and their effect on the ductility: The deformation mechanisms of an extruded Mg-5Y-0.08Ca (wt. %) alloy were\nanalyzed by means of micropillar compression tests on single crystals along\ndifferent orientations -- selected to activate specific deformation modes -- as\nwell as slip trace analysis, transmission electron microscopy and transmission\nKikuchi diffraction. The polycrystalline alloy presented a remarkable ductility\nin tension (~32%) and negligible differences in the yield strength between\ntension and compression. It was found that the presence of Y and Ca in solid\nsolution led to a huge increase in the CRSS for <a> basal slip (29 $\\pm$ 5\nMPa), <c+a> pyramidal slip (203 $\\pm$ 7 MPa) and tensile twin nucleation (above\n148 MPa), while the CRSS for <a> prismatic slip only increases up to 105 $\\pm$\n4 MPa. The changes in the CRSS for slip and tensile twinning in Mg-Y-Ca alloys\nexpectedly modify the dominant deformation mechanisms in polycrystals. In\nparticular, tensile twinning is replaced by <a> prismatic slip during\ncompressive deformation along the a-axis. The reduction of twinning (which\ngenerally induces strong anisotropy in the plastic deformation in textured\nalloys), and the activation of <a> prismatic slip (which provides an additional\nplastic deformation mechanism with limited hardening) were responsible for the\nlarge tensile ductility of the alloy."
    },
    {
        "anchor": "Nanograined half-Heusler semiconductors as advanced thermoelectrics: an\n  ab-initio high-throughput statistical study: Nanostructuring has spurred a revival in the field of direct thermoelectric\nenergy conversion. Nanograined materials can now be synthesized with higher\nfigures of merit (ZT) than the bulk counterparts. This leads to increased\nconversion efficiencies. Despite considerable effort in optimizing the known\nand discovering the unknown, technology still relies upon a few limited\nsolutions. Here we perform ab-initio modeling of ZT for 75 nanograined\ncompounds obtained by filtering down the 79,057 half-Heusler entries available\nin the AFLOWLIB.org repository according to electronic and thermodynamic\ncriteria. For many of the compounds the $ZT$s are markedly above those\nattainable with nanograined IV and III-V semiconductors. About 15% of them may\neven outperform ZT~2 at high temperatures. Our analysis elucidates the origin\nof the advantageous thermoelectric properties found within this broad material\nclass. We use machine learning techniques to unveil simple rules determining if\na nanograined half-Heusler compound is likely to be a good thermoelectric given\nits chemical composition.",
        "positive": "Studies of non-trivial band topology and electron-hole compensation in\n  YSb: In this article, we study non-trivial topological phase and electron-hole\ncompensation in extremely large magnetoresistance (XMR) material YSb under\nhydrostatic pressure using first-principles calculations. YSb is topologically\ntrivial at ambient pressure, but undergoes a reentrant topological phase\ntransition under hydrostatic pressure. The reentrant behavior of topological\nquantum phase is then studied as a function of charge density ratio under\npressure. From the detailed investigation of Fermi surfaces, it is found that\nelectron to hole densities ratio increases with pressure, however a non-trivial\ntopological phase appears without perfect electron-hole compensation. The\nresults indicate that the non-trivial topological phase under hydrostatic\npressure may not have maximal influence on the magnetoresistance, and need\nfurther investigations through experiments to determine the exact relationship\nbetween topology and XMR effect."
    },
    {
        "anchor": "Calculation of Elastic Green's Functions for Lattices with Cavities: In this Brief Report, we present an algorithm for calculating the elastic\nLattice Greens Function of a regular lattice, in which defects are created by\nremoving lattice points. The method is computationally efficient, since the\nrequired matrix operations are on matrices that scale with the size of the\ndefect subspace, and not with the size of the full lattice. This method allows\nthe treatment of force fields with multi-atom interactions.",
        "positive": "Strategies to reduce the thermoelastic loss of multimaterial coated\n  finite substrates: Thermoelastic loss is an important energy dissipation mechanisms in resonant\nsystems. A careful analysis of the thermoelastic loss is critical to the design\nof low-noise devices for high-precision applications, such as the mirrors used\nfor gravitational-wave detectors. In this paper, we present analytical\nsolutions to the thermoelastic loss due to thermoelasticity between different\nmaterials that are in contact. We find expressions for the thermoelastic loss\nof multimaterial coatings of finite substrates, and analyze its dependencies on\nmaterial properties, mirror design and operating experimental conditions. Our\nresults show that lower operating mirror temperature, thinner layers and higher\nnumber of interfaces in the coating, and the choice of the first layer of the\ncoating that minimizes the thermal expansion mismatch with the substrate are\nstrategies that reduce the thermoelastic loss and, therefore, diminish the\nthermal noise that limits the resolution in sensing applications. The results\npresented in this paper are relevant for the development of low-noise\ngravitational-wave detectors and for other experiments sensitive to energy\ndissipation mechanisms when different materials are in contact."
    },
    {
        "anchor": "Investigation of Arrott plot and magnetocaloric effect in the complex\n  CaMn7O12 perovskite: Detailed magnetic studies including magneto-caloric measurements on magnetic\nmultiferroic quadruple perovskite CaMn7O12 are presented. Based on the\ncollective response of Arrott plots and {\\Delta}SM (T), a magnetic phase\ndiagram of CaMn7O12 is suggested. A new magnetic transition at TN3 ~20 K where\nthe system changes from noncollinear AFM to collinear AFM is reported. An\nanomaly observed in both {\\Delta}SM (T) and Arrott plots around 64 K has been\nattributed to high external field induced spin canting leading to change in\nmagnetic order inducing phase transition. Magneto-caloric effect in this\nmaterial is presented for the first time. The peak value of change in\nisothermal magnetic entropy is 1.3 J/K-Kg and the value of refrigeration\ncapacity is reported to be 34.5 J/Kg for the field of 7 T.",
        "positive": "Tribological Behavior of Very Thin Confined Films: The tribological properties of two smooth surfaces in the presence of a thin\nconfined film are investigated with a generic model for the interaction between\ntwo surfaces and with computer simulations. It is shown that at large normal\ncontact pressures, an ultra thin film automatically leads to static friction\nbetween two flat surfaces - even if the surfaces are incommensurate.\nCommensurability is nevertheless the key quantity to understand the\ntribological behavior of the contact. Qualitative differences between\ncommensurate and incommensurate contacts remain even in the presence of a thin\nfilm. The differences mainly concern the thermal diffusion of the contact and\nthe transition between smooth sliding and stick-slip."
    },
    {
        "anchor": "Impact of micro-alloying on the plasticity of Pd-based Bulk Metallic\n  Glasses: Micro-alloying was performed using additions of Co and Fe to monolithic\nPd40Ni40P20 bulk metallic glass to study selectively the influence on the\nplastic behavior in uniaxial compression and three-point bending tests. The\ncorresponding Poisson's ratios were determined by ultrasonic measurements. The\nmicrostructure of the individual bulk metallic glasses was characterized by\nelectron microscopy, X-ray diffraction and calorimetry. A plastic strain of 13%\nwas found for the Co addition (1 at.%), whereas the Fe addition (0.6 at.%) led\nto immediate failure after reaching the elastic limit. Surprisingly, the\nplasticity is not reflected by the high Poisson's ratio of 0.4 since it\nremained unaffected by the minor alloying.",
        "positive": "Single step precursor free synthesis and characterisation of stable Au\n  nanochains by laser ablation: In this paper we report a simple one step and one-pot synthesis of stable\nassembly of Au nanoparticles (diameter 8-10nm) into chains in an Ethylene\nGlycol medium, using only a solid metallic Au target and a pulsed excimer laser\n({\\lambda}=248nm). The process reported does not use any precursor, reducing\nagent or surfactant and thus can be described as chemistry free synthesis\nroute. The Au nanoparticle-ethylene glycol nanochains (with unbroken lengths\noften more than few microns) formed in liquid medium are mechanically as well\nas thermally stable and can be transferred unchanged into a solid substrate\nwhich can span a large surface area. The nanochains show a broad optical\nabsorption covering almost the complete visible spectrum. A hybrid consisting\nof Au nanochains and separated nanoparticles can be formed by the same method\nusing a proper choice of the laser fluence and Ethylene Glycol /DI water\nconcentration. The Au nanochain - Ethylene Glycol hybrid material formed by the\nabove method shows enhanced low frequency dielectric constant (one order more\nthan the Ethylene Glycol) and enhanced electrical conductivity even with low Au\nfill fraction can show enhancement up to two orders. Based on 2D-NMR\nexperiments we suggest that the quasi-1D chain like structure forms due to the\nformation of dimer and trimers of Ethylene Glycol molecules that attach to the\nAu nanoparticles formed by the ablation process and facilitate the chain\nformation."
    },
    {
        "anchor": "Exploring Structural and Electrochemical Properties of Li$_3$TiCl$_6$: A\n  Machine Learning Molecular Dynamics Study: We performed large-scale molecular dynamics simulations based on a\nmachine-learning force field (MLFF) to investigate the Li-ion transport\nmechanism in cation-disordered Li$_3$TiCl$_6$ cathode at six different\ntemperatures, ranging from 25$^\\mathrm{o}$C to 100$^\\mathrm{o}$C. In this work,\ndeep neural network method and data generated by $ab-initio$ molecular dynamics\n(AIMD) simulations were deployed to build a high-fidelity MLFF. Radial\ndistribution functions, Li-ion mean square displacements (MSD), diffusion\ncoefficients, ionic conductivity, activation energy, and crystallographic\ndirection-dependent migration barriers were calculated and compared with\ncorresponding AIMD and experimental data to benchmark the accuracy of the MLFF.\nFrom MSD analysis, we captured both the self and distinct parts of Li-ion\ndynamics. The latter reveals that the Li-ions are involved in anti-correlation\nmotion that was rarely reported for solid-state materials. Similarly, the self\nand distinct parts of Li-ion dynamics were used to determine Haven's ratio to\ndescribe the Li-ion transport mechanism in Li$_3$TiCl$_6$. Obtained trajectory\nfrom molecular dynamics infers that the Li-ion transportation is mainly through\ninterstitial hopping which was confirmed by intra- and inter-layer Li-ion\ndisplacement with respect to simulation time. Ionic conductivity (1.06 mS/cm)\nand activation energy (0.29eV) calculated by our simulation are highly\ncomparable with that of experimental values. Overall, the combination of\nmachine-learning methods and AIMD simulations explains the intricate\nelectrochemical properties of the Li$_3$TiCl$_6$ cathode with remarkably\nreduced computational time. Thus, our work strongly suggests that the deep\nneural network-based MLFF could be a promising method for large-scale complex\nmaterials.",
        "positive": "Giant magnetothermopower in charge ordered Nd0.75Na0.25MnO3: We report magnetization, resistivity and thermopower in the charge-orbital\nordered antiferromagnet Nd0.75Na0.25MnO3. Magnetic-field induced collapse of\nantiferromagnetism is found to be accompanied by a giant negative\nmagnetothermopower (= 80-100% for a field change of 5T) over a wide temperature\n(T = 60-225K) and giant magnetoresistance. While the field-induced metamagnetic\ntransition in magnetization is reversible upon field-cycling at T > 40 K, it is\nirreversible at lower temperatures and this has impact on magnetoresistance,\nmagnetothermopower as well as change in the temperature of the sample. Our\nresults indicate high sensitivity of thermopower to changes in the magnetic\nstate of the sample."
    },
    {
        "anchor": "Nanoscale Surface Dynamics of Bi$_2$Te$_3$(111): Observation of a\n  Prominent Surface Acoustic Wave and the Role of van der Waals Interactions: We present a combined experimental and theoretical study of the surface\nvibrational modes of the topological insulator Bi$_2$Te$_3$. Using\nhigh-resolution helium-3 spin-echo spectroscopy we are able to resolve the\nacoustic phonon modes of Bi$_2$Te$_3$(111). The low energy region of the\nlattice vibrations is mainly dominated by the Rayleigh mode which has been\nclaimed to be absent in previous experimental studies. The appearance of the\nRayleigh mode is consistent with previous bulk lattice dynamics studies as well\nas theoretical predictions of the surface phonon modes. Density functional\nperturbation theory calculations including van der Waals corrections are in\nexcellent agreement with the experimental data. Comparison of the experimental\nresults with theoretically obtained values for films with a thickness of\nseveral layers further demonstrate, that for an accurate theoretical\ndescription of three-dimensional topological insulators with their layered\nstructure the inclusion of van der Waals corrections is essential. The presence\nof a prominent surface acoustic wave and the contribution of van der Waals\nbonding to the lattice dynamics may hold important implications for the\nthermoelectric properties of thin-film and nanoscale devices.",
        "positive": "Tuning of topological properties in the strongly correlated\n  antiferromagnet Mn$_3$Sn via Fe doping: Magnetic topological materials, in which strong correlations between magnetic\nand electronic properties of matter, give rise to various exotic phenomena such\nas anomalous Hall effect (AHE), topological Hall effect (THE), and skyrmion\nlattice. Here, we report on the electronic, magnetic, and topological\nproperties of Mn$_{3-\\it{x}}$Fe$_{\\it{x}}$Sn single crystals ($\\it{x}$=0, 0.25,\nand 0.35). Low temperature magnetic properties have been significantly changed\nwith Fe doping. Most importantly, we observe that large uniaxial\nmagnetocrystalline anisotropy that is induced by the Fe doping in combination\nwith competing magnetic interactions at low temperature produce nontrivial\nspin-texture, leading to large topological Hall effect in the doped systems at\nlow temperatures. Our studies further show that the topological properties of\nMn$_{3-\\it{x}}$Fe$_{\\it{x}}$Sn are very sensitive to the Fe doping."
    },
    {
        "anchor": "Full Temperature-Dependent Potential and Anharmonicity in Metallic\n  Hydrogen: Colossal NQE and the Consequences: The temperature-dependent effective potential (TDEP) method for anharmonic\nphonon dispersion is generalized to the full potential case by combining with\npath integral formalism. This extension naturally resolves the intrinsic\ndifficulty in the original TDEP at low temperature. The new method is applied\nto solid metallic hydrogen at high pressure. A colossal nuclear quantum effect\n(NQE) and subsequent anharmonicity are discovered, which not only leads to\nunexpectedly large drift of protons, but also slows down the convergence rate\nsubstantially when computing the phonon dispersions. By employing direct ab\ninitio path integral molecular dynamics simulations as the benchmark, a\npossible breakdown of phonon picture in metallic hydrogen due to colossal NQE\nis indicated, implying novel lattice dynamical phenomena might exist. Inspired\nby this observation, a general theoretical formalism for quantum lattice\ndynamics beyond phonon is sketched, with the main features being discussed.",
        "positive": "CVD of CrO2 Thin Films: Influence of the Deposition Parameters on their\n  Structural and Magnetic Properties: This work reports on the synthesis of CrO2 thin films by atmospheric pressure\nCVD using chromium trioxide (CrO3) and oxygen. Highly oriented (100) CrO2 films\ncontaining highly oriented (0001) Cr2O3 were grown onto Al2O3(0001) substrates.\nFilms display a sharp magnetic transition at 375 K and a saturation\nmagnetization of 1.92 Bohr magnetons per f.u., close to the bulk value of 2\nBohr magnetons per f.u. for the CrO2.\n  Keywords: Chromium dioxide (CrO2), Atmospheric pressure CVD, Spintronics."
    },
    {
        "anchor": "The Limits of Resolution and Dose for Aberration-Corrected Electron\n  Tomography: Aberration-corrected electron microscopy can resolve the smallest atomic\nbond-lengths in nature. However, the high-convergence angles that enable\nspectacular resolution in 2D have unknown 3D resolution limits for all but the\nsmallest objects ($< \\sim$8nm). We show aberration-corrected electron\ntomography offers new limits for 3D imaging by measuring several focal planes\nat each specimen tilt. We present a theoretical foundation for\naberration-corrected electron tomography by establishing analytic descriptions\nfor resolution, sampling, object size, and dose---with direct analogy to the\nCrowther-Klug criterion. Remarkably, aberration-corrected scanning transmission\nelectron tomography can measure complete 3D specimen structure of unbounded\nobject sizes up to a specified cutoff resolution. This breaks the established\nCrowther limit when tilt increments are twice the convergence angle or smaller.\nUnprecedented 3D resolution is achievable across large objects. Atomic 3D\nimaging (1$\\unicode{xC5}$) is allowed across extended objects larger than\ndepth-of-focus (e.g. $>$ 20nm) using available microscopes and modest specimen\ntilting ($<$ 3$^\\circ$). Furthermore, aberration-corrected tomography follows\nthe rule of dose-fractionation where a specified total dose can be divided\namong tilts and defoci.",
        "positive": "Refinements for Bragg coherent X-ray diffraction imaging: Electron\n  backscatter diffraction alignment and strain field computation: Bragg coherent X-ray diffraction imaging (BCDI) allows the three-dimensional\n(3D) measurement of lattice strain along the scattering vector for specific\nmicrocrystals. If at least three linearly independent reflections are measured,\nthe 3D variation of the full lattice strain tensor within the microcrystal can\nbe recovered. However, this requires knowledge of the crystal orientation,\nwhich is typically attained via estimates based on crystal geometry or\nsynchrotron micro-beam Laue diffraction measurements. Here, we present an\nalternative method to determine the crystal orientation for BCDI measurements,\nby using electron backscatter diffraction (EBSD) to align Fe-Ni and Co-Fe alloy\nmicrocrystals on three different substrates. The orientation matrix is\ncalculated from EBSD Euler angles and compared to the orientation determined\nusing micro-beam Laue diffraction. The average angular mismatch between the\norientation matrices is less than ~6 degrees, which is reasonable for the\nsearch for Bragg reflections. We demonstrate the use of an orientation matrix\nderived from EBSD to align and measure five reflections for a single Fe-Ni\nmicrocrystal using multi-reflection BCDI. Using this dataset, a refined strain\nfield computation based on the gradient of the complex exponential of the phase\nis developed. This approach is shown to increase accuracy, especially in the\npresence of dislocations. Our results demonstrate the feasibility of using EBSD\nto pre-align BCDI samples and the application of more efficient approaches to\ndetermine the lattice strain tensor with greater accuracy."
    },
    {
        "anchor": "Lone pair driven anisotropy in antimony chalcogenide semiconductors: Antimony sulfide (Sb2S3) and selenide (Sb2Se3) have emerged as promising\nearth-abundant alternatives among thin-film photovoltaic compounds. A\ndistinguishing feature of these materials is their anisotropic crystal\nstructures, which are composed of quasi-one-dimensional (1D) [Sb4X6]n ribbons.\nThe interaction between ribbons has been reported to be van der Waals (vdW) in\nnature and Sb2X3 are thus commonly classified in the literature as 1D\nsemiconductors. However, based on first-principles calculations, here we show\nthat inter-ribbon interactions are present in Sb2X3 beyond the vdW regime. The\norigin of the anisotropic structures is related to the stereochemical activity\nof the Sb 5s lone pair according to electronic structure analysis. The impacts\nof structural anisotropy on the electronic and optical properties are further\nexamined, including the presence of higher dimensional Fermi surfaces for\ncharge carrier transport. Our study provides guidelines for optimising the\nperformance of Sb2X3-based solar cells via device structuring based on the\nunderlying crystal anisotropy.",
        "positive": "Distinctive Thermoelectric Properties of Supersaturated Si-Ge-P\n  Compounds: Achieving Figure of Merit ZT > 3.6: The efficiency of energy conversion in thermoelectric generators (TEGs) is\ndirectly proportional to electrical conductivity and Seebeck coefficient while\ninversely to thermal conductivity. The challenge is to optimize these\ninterdependent parameters simultaneously. In this work, the problem is\naddressed with a novel approach of nanostructuring and constructive electronic\nstructure modification to achieve a very high value of dimensionless figure of\nmerit ZT greater than 3.6 at 1000 K with negative Seebeck coefficient.\nSupersaturated solid-solutions of Si-Ge containing 1 atomic percent Fe and 10\natomic percent P are prepared by high-energy ball milling. The bulk samples\nconsisting of ultra-fine nano-crystallites 9.7 nm are obtained by the\nsophisticated low-temperature & high-pressure sintering process. Despite that\nthe electrical resistivity is slightly high due to the localization of\nelectrons is associated with the highly disordered structure and low electrical\ndensity of states near the chemical potential, a very low thermal conductivity\n\\k{appa} less than 1 W m-1K-1 and very large magnitude of Seebeck coefficient\nexceeding 470 uV K-1 are achieved in association with the nanostructuring and\nthe Fe 3d impurity states, respectively, to realize a very large magnitude of\nZT."
    },
    {
        "anchor": "A First-principles approach to predict Seebeck coefficients: Application\n  to La3-xTe4: Theoretical descriptions of the Seebeck coefficient in terms of the\ndifferential electrical conductivity given by Cutler and Mott is the foundation\nof later works in terms of transmission function from the thermoelectric\ntransport theory. On the other hand, recent studies in the literature have\nshown the relation between the Seebeck coefficient and chemical potential of\nelectrons. In this work, this relation is rigorously derived from fundamental\nthermodynamics, and an formalism for the parameter-free calculation of the\nSeebeck coefficient based on the electronic density-of-states from\nfirst-principles calculations is presented. Numerical results are given using\nthe n-type La3-xTe4 thermoelectric material as the prototype. With the rigid\nband approximation, the calculated temperature dependences of the Seebeck\ncoefficients of La3-xTe4 as a function of carrier concentration show excellent\nagreements with experimental data.",
        "positive": "Oxygen diffusion pathways in brownmillerite SrCoO2.5: Influence of\n  structure and chemical potential: To design and discover new materials for next-generation energy materials\nsuch as solid-oxide fuel cells (SOFCs), a fundamental understanding of their\nionic properties and behaviors is essential. The potential applicability of a\nmaterial for SOFCs is critically determined by the activation energy barrier of\noxygen along various diffusion pathways. In this work, we investigate\ninterstitial-oxygen (Oi) diffusion in brownmillerite oxide SrCoO2.5, employing\na first-principles approach. Our calculations indicate highly anisotropic ionic\ndiffusion pathways, which result from its anisotropic crystal structure. The\none-dimensional-ordered oxygen vacancy channels are found to provide the\neasiest diffusion pathway with an activation energy barrier height of 0.62 eV.\nThe directions perpendicular to the vacancy channels have higher energy\nbarriers for Oint diffusion. In addition, we have studied migration barriers\nfor oxygen vacancies that could be present as point defects within the\nmaterial. This in turn could also facilitate the transport of oxygen.\nInterestingly, for oxygen vacancies, the lowest barrier height was found to\noccur within the octahedral layer with an energy of 0.82 eV. Our results imply\nthat interstitial migration would be highly one-dimensional in nature. Oxygen\nvacancy transport, on the other hand, could preferentially occur in the\ntwo-dimensional octahedral plane."
    },
    {
        "anchor": "Effect of inplane electric field on magnetotransport in helical metal: The existence of helical surface states in a bulk insulator, with anomalous\nmagneto-electric properties, is a remarkable new development in solid state\nphysics. The linear dispersion of the the fermions leads to a form of Lorentz\ninvariance, with the Fermi velocity playing the role of the velocity of light\n($c$). In a crossed electric and magnetic field the single particle states form\nLandau levels whose energies can be changed by varying the applied\n\\emph{in-plane electric} field. The degeneracy remains constant and is\ndetermined by the magnetic field. In the letter we study the nature of the\nmangeto-oscillation in conductivity and thermopower as a function of the\n\\emph{in-plane electric} field.",
        "positive": "Distinct origins of magnetic -field -induced resistivity irreversibility\n  in two manganites with similar ground states :\n  Pr$_{0.5}$Sr$_{0.41}$Ca$_{0.09}$MnO$_{3}$ and La$_{0.5}$Ca$_{0.5}$MnO$_{3}$: Our investigation of the magnetotransport in two charge ordered manganites\nwith similar magnetic ground states reveals that the origin of\nmagnetoresistance can not be concluded from the isofield resistivity, $\\rho\n$(T, constant H), measurements alone. Both\nPr$_{0.5}$Sr$_{0.41}$Ca$_{0.09}$MnO$_{3}$ (PrSrCa) and\nLa$_{0.5}$Ca$_{0.5}$MnO$_{3}$ (LaCa) show a ferromagnetic transition (T$_{C}$ =\n260 K for PrSrCa, 230 K for LaCa) followed by an antiferromagnetic transition\n(T$_{N}$ = 170 K for PrSrCa, 140 K for LaCa). These compounds show\nqualitatively similar magnetotransport : Below the irreversibility temperature\nT$_{IR}$, field cooled (FC) resistivity is lower than zero field cooled (ZFC)\nand decreases continuously with T, whereas the ZFC $\\rho $(T, H) resembles $\\\n$the behavior of $\\rho $(T, H = 0 T). The value of $\\rho $(ZFC)/$\\rho $(FC) is\n$\\approx $ 10$^{4}$ at 5 K and $\\mu_{0}$H = 7 T in both compounds. However,\nisothermal magnetic measurements suggest distinct origins of magnetoresistance\n: Field cooling enhances ferromagnetic phase fraction in LaCa whereas it drives\nPrSrCa into a metastable state with high magnetization. The distinct origins of\nmagnetotransport is also reflected in other magnetic history dependent\nproperties."
    },
    {
        "anchor": "Real-space investigation of polarons in hematite Fe2O3: In polarizable materials, electronic charge carriers interact with the\nsurrounding ions, leading to quasiparticle behaviour. The resulting polarons\nplay a central role in many materials properties including electrical\ntransport, optical properties, surface reactivity and magnetoresistance, and\npolaron properties are typically investigated indirectly through such\nmacroscopic characteristics. Here, noncontact atomic force microscopy (nc-AFM)\nis used to directly image polarons in Fe2O3 at the single quasiparticle limit.\nA combination of Kelvin probe force microscopy (KPFM) and kinetic Monte Carlo\n(KMC) simulations shows that Ti doping dramatically enhances the mobility of\nelectron polarons, and density functional theory (DFT) calculations indicate\nthat a metallic transition state is responsible for the enhancement. In\ncontrast, hole polarons are significantly less mobile and their hopping is\nhampered further by the introduction of trapping centres.",
        "positive": "Full stress tensor measurement using colour centres in diamond: Stress and strain are important factors in determining the mechanical,\nelectronic, and optical properties of materials, relating to each other by the\nmaterial's elasticity or stiffness. Both are represented by second rank field\ntensors with, in general, six independent components. Measurements of these\nquantities are usually achieved by measuring a property that depends on the\ntranslational symmetry and periodicity of the crystal lattice, such as optical\nphonon energies using Raman spectroscopy, the electronic band gap using\ncathodoluminescence, photoelasticity via the optical birefringence, or Electron\nBack Scattering Diffraction (EBSD). A reciprocal relationship therefore exists\nbetween the maximum sensitivity of the measurements and the spatial resolution.\nFurthermore, of these techniques, only EBSD and off-axis Raman spectroscopy\nallow measurement of all six components of the stress tensor, but neither is\nable to provide full 3D maps. Here we demonstrate a method for measuring the\nfull stress tensor in diamond, using the spectral and optical polarization\nproperties of the photoluminescence from individual nitrogen vacancy (NV)\ncolour centres. We demonstrate a sensitivity of order 10 MPa, limited by local\nfluctuations in the stress in the sample, and corresponding to a strain of\nabout 10^-5, comparable with the best sensitivity provided by other techniques.\nBy using the colour centres as built-in local sensors, the technique overcomes\nthe reciprocal relationship between spatial resolution and sensitivity and\noffers the potential for measuring strains as small as 10^-9 at spatial\nresolution of order 10 nm. Furthermore it provides a straightforward route to\nvolumetric stress mapping. Aside from its value in understanding strain\ndistributions in diamond, this new approach to stress and strain measurement\ncould be adapted for use in micro or nanoscale sensors."
    },
    {
        "anchor": "Interferometric 4D-STEM for Lattice Distortion and Interlayer Spacing\n  Measurements in Bilayer and Trilayer Two-dimensional Materials: Van der Waals materials composed of stacks of individual atomic layers have\nattracted considerable attention due to their exotic electronic properties that\ncan be altered by, for example, manipulating the twist angle of bilayer\nmaterials or the stacking sequence of trilayer materials. To fully understand\nand control the unique properties of these few-layer materials, a technique\nthat can provide information about their local in-plane structural\ndeformations, twist direction, and out-of-plane structure is needed. In\nprinciple, interference in overlap regions of Bragg disks originating from\nseparate layers of a material encodes three-dimensional information about the\nrelative positions of atoms in the corresponding layers. Here, we describe an\ninterferometric four-dimensional scanning transmission electron microscopy\ntechnique that utilizes this phenomenon to extract precise structural\ninformation from few-layer materials with nm-scale resolution. We demonstrate\nhow this technique enables measurement of local pm-scale in-plane lattice\ndistortions as well as twist direction and average interlayer spacings in\nbilayer and trilayer graphene, and therefore provides a means to better\nunderstand the interplay between electronic properties and precise structural\narrangements of few-layer 2D materials.",
        "positive": "Statistics of dislocation pinning at localized obstacles: Pinning of dislocations at nanosized obstacles like precipitates, voids and\nbubbles, is a crucial mechanism in the context of phenomena like hardening and\ncreep. The interaction between such an obstacle and a dislocation is often\nexplored at fundamental level by means of analytical tools, atomistic\nsimulations and finite element methods. Nevertheless, the information extracted\nfrom such studies has not been utilized to its maximum extent on account of\ninsufficient information about the underlying statistics of this process\ncomprising a large number of dislocations and obstacles in a system. Here we\npropose a new statistical approach, where the statistics of pinning of\ndislocations by idealized spherical obstacles is explored by taking into\naccount the generalized size-distribution of the obstacles along with the\ndislocation density within a three-dimensional framework. The application of\nthis approach, in combination with the knowledge of fundamental\ndislocation-obstacle interactions, has successfully been demonstrated for\ndislocation pinning at nanovoids in neutron irradiated type 316-stainless steel\nin regard to both conservative and non-conservative motions of dislocations."
    },
    {
        "anchor": "Goodenough-Kanamori-Anderson rules in 2D magnet: A chemical trend in\n  MCl2 with M=V, Mn, and Ni: Density-functional-theory calculations were performed to investigate the\nmagnetism in a series of triangular-lattice monolayer MCl2 (M=V, Mn, and Ni).\nThe magnetic stability manifests a distinct chemical trend; VCl2 and MnCl2 show\nthe antiferromagnetic ground states and NiCl2 shows the ferromagnetic ground\nstate. The microscopic mechanism behind the magnetic interaction is explained\nby the so-called Goodenough-Kanamori-Anderson rules and by the virtual-hopping\nprocess through the hopping integrals between the 3d-orbital maximally\nlocalized Wannier functions. Our result highlights the role of the direct\nexchange interaction and the superexchange interaction in the magnetic\nstabilization in two-dimensional magnets.",
        "positive": "Size and shape-dependent melting mechanism of Pd nanoparticles: Molecular dynamics simulation is employed to understand the thermodynamic\nbehavior of cuboctahedron (cub) and icosahedron (ico) nanoparticles with 2-20\nnumber of full shells. The original embedded atom method (EAM) was compared to\nthe more recent highly optimized version as inter-atomic potential. The thermal\nstability of clusters were probed using potential energy and specific heat\ncapacity as well as structure analysis by radial distribution function, G(r),\nand common neighbor analysis (CNA), simultaneously, to make a comprehensive\npicture of the solid state and melting transitions. The result shows ico is the\nonly stable shape of small clusters (Pd55-Pd309 using original EAM and Pd55\nusing optimized version) those are melting uniformly due to their small\ndiameter. An exception is cub Pd309 modeled via optimized EAM that transforms\nto ico at elevated temperatures. A similar cub to ico transition was predicted\nby original EAM for Pd923-Pd2075 clusters while for the larger clusters both\ncub and ico are stable up to the melting point. As detected by G(r) and CNA,\nmoderate and large cub clusters were showing surface melting by nucleation of\nthe liquid phase at (100) planes and growth of liquid phase at the surface\nbefore inward growth. While diagonal (one corner to another) melting was\ndominating over ico clusters owing to their partitioned structure which\nretarded the growth of the liquid phase. The large ico cluster, using optimized\nEAM, presented a combination of surface and diagonal melting due to the\nsimultaneous diagonal melting started from different corners. Finally, the\nmelting temperature as well as latent heat of fusion were calculated and\ncompared with available models and previous studies which showed, unlike the\npresent result, the models failed to predict size-dependent motif crossover."
    },
    {
        "anchor": "Polarization Relaxation Induced by Depolarization Field in Ultrathin\n  Ferroelectric BaTiO$_3$ Capacitors: Time-dependent polarization relaxation behaviors induced by a depolarization\nfield $E_{d}$ were investigated on high-quality ultrathin\nSrRuO$_{3}$/BaTiO$_{3}$/SrRuO$_{3}$ capacitors. The $E_d$ values were\ndetermined experimentally from an applied external field to stop the net\npolarization relaxation. These values agree with those from the electrostatic\ncalculations, demonstrating that a large $E_{d}$ inside the ultrathin\nferroelectric layer could cause severe polarization relaxation. For numerous\nferroelectric devices of capacitor configuration, this effect will set a\nstricter size limit than the critical thickness issue.",
        "positive": "Light controlled magnetoresistance and magnetic field controlled\n  photoresistance in CoFe film deposited on BiFeO3: We present a magnetoresistive-photoresistive device based on the interaction\nof a piezomagnetic CoFe thin film with a photostrictive BiFeO3 substrate that\nundergoes light-induced strain. The magnitude of the resistance and\nmagnetoresistance in the CoFe film can be controlled by the wavelength of the\nincident light on the BiFeO3. Moreover, a light-induced decrease in anisotropic\nmagnetoresistance is detected due to an additional magnetoelastic contribution\nto magnetic anisotropy of the CoFe film. This effect may find applications in\nphoto-sensing systems, wavelength detectors and can possibly open a research\ndevelopment in light-controlled magnetic switching properties for next\ngeneration magnetoresistive memory devices."
    },
    {
        "anchor": "77Se NMR Investigation of Fe-doped Bi2Se3: Bismuth selenide is both a thermoelectric material and topological insulator.\nDefects and dopants create conduction in thermoelectric applications. However,\nsuch defects may degrade the performance as a topological insulator (TI).\nMagnetic impurities such as iron open a band gap at the Dirac point on the\nsurface. Since magnetically-doped TIs are important in technological\napplications, a good understanding of their properties is needed. In this\narticle, 77Se nuclear magnetic resonance (NMR) spectroscopy has been used to\ninvestigate Fe-doped Bi2Se3. Spin-lattice relaxation measurements indicate that\nthe Fe dopants provide a spin diffusion relaxation mechanism at low\ntemperatures for the 77Se. Above 320 K, the predominant 77Se relaxation\nmechanism resulting from interaction with the conduction carriers is thermally\ninduced with an activation energy of 21.5 kJ/mol (5.1 kcal/mol, 222 meV) and\nlikely arises from inter-band excitations. Magic-angle spinning produces\nnegligible narrowing of the 77Se resonance at 7 T, suggesting a statistical\ndistribution of material defects and is also consistent with a dipolar\ninteraction with the neighboring quadrupolar nucleus.",
        "positive": "Trion dynamics in coupled double quantum wells. Electron density effects: We have studied the coherent dynamics of injected electrons when they are\neither free or bounded both in excitons and in trions (charged excitons). We\nhave considered a remotely doped asymmetric double quantum well where an excess\nof free electrons and the direct created excitons generate trions. We have used\nthe matrix density formalism to analyze the electron dynamics for different\nconcentration of the three species. Calculations show a significant\nmodification of the free electron inter-sublevel oscillations cWe have studied\nthe coherent dynamics of injected electrons when they are aused by electrons\nbound in excitons and trions. Based on the present calculations we propose a\nmethod to detect trions through the emitted electromagnetic radiation or the\ncurrent density."
    },
    {
        "anchor": "Real space investigation of structural changes at the metal-insulator\n  transition in VO2: Synchrotron X-ray total scattering studies of structural changes in rutile\nVO2 at the metal-insulator transition temperature of 340 K reveal that\nmonoclinic and tetragonal phases of VO2 coexist in equilibrium, as expected for\na first-order phase transition. No evidence for any distinct intermediate phase\nis seen. Unbiased local structure studies of the changes in V--V distances\nthrough the phase transition, using reverse Monte Carlo methods, support the\nidea of phase coexistence and point to the high degree of correlation in the\ndimerized low-temperature structure. No evidence for short range V--V\ncorrelations that would be suggestive of local dimers is found in the metallic\nphase.",
        "positive": "Three-dimensionality of mobile electrons at X-ray-irradiated\n  LaAlO$_3$/SrTiO$_3$ interfaces: Effects of X-ray irradiation on the electronic structure of\nLaAlO$_3$/SrTiO$_3$ (LAO/STO) samples, grown at low oxygen pressure and\npost-annealed ex-situ till recovery of their stoichiometry, were investigated\nby soft-X-ray ARPES. The irradiation at low sample temperature below ~100K\ncreates oxygen vacancies (VOs) injecting Ti t2g-electrons into the interfacial\nmobile electron system (MES). At this temperature the oxygen out-diffusion is\nsuppressed, and the VOs are expected to appear mostly in the top STO layer.\nHowever, we observe a pronounced three-dimensional (3D) character of the X-ray\ngenerated MES in our samples, indicating its large extension into the STO\ndepth, which contrasts to the purely two-dimensional (2D) character of the MES\nin standard stoichiometric LAO/STO samples. Based on self-interaction-corrected\nDFT calculations of the MES induced by VOs at the interface and in STO bulk, we\ndiscuss possible mechanisms of this puzzling three-dimensionality. They may\ninvolve VOs remnant in the deeper STO layers, photoconductivity-induced\nmetallic states as well as more exotic mechanisms such as X-ray induced\nformation of Frenkel pairs."
    },
    {
        "anchor": "An unprecedented synergy of high-temperature tensile strength and\n  ductility in a NiCoCrAlTi high-entropy alloy: The present work reported a novel L12-strengthening NiCoCrAlTi high entropy\nalloy (HEA) with an outstanding synergy of tensile strength and ductility at\nboth ambient and high temperatures. Transmission electron microscopy (TEM)\ncharacterization revealed a high density of rod-like and spheroidal L12\nprecipitates distributing in the micro/nanograins and non-recrystallized\nregions in the annealed specimens. The tremendously high yield stress, ultimate\ntensile stress (UTS), and ductility of the HEA at 600 C were ~1060 MPa, 1271\nMPa, and 25%, respectively, which were significantly superior to most reported\nHEAs and Co- and Ni-based superalloys to date. Systematic TEM analysis unveiled\nthat the cooperation among L12 precipitation, extensive stacking faults (SFs),\ndeformation twins (DTs), immobile Lomer-Cottrell (L-C) locks formed from\ninteractions between SFs and SFs/DTs, hierarchical SFs/DTs networks, as well as\nhetero-deformation-induced strengthening dominated the plastic deformation at\n600 C. Such a unique deformation mechanism enabled extremely high tensile\nstrength and sustained ductility of the HEA at a high temperature.",
        "positive": "Fatigue Deformation of Polycrystalline Cu Using Molecular Dynamics\n  Simulations: Molecular dynamics (MD) simulations have been performed to investigate the\nfatigue deformation behaviour of polycrystalline Cu with grain size of 5.4 nm.\nThe samples were prepared using Voronoi algorithm with random grain\norientations. Fatigue simulations were carried out by employing fully reversed,\ntotal strain controlled cyclic loading at strain amplitude of $\\pm4$\\% for 10\ncycles. The MD simulation results indicated that the deformation behaviour\nunder cyclic loading is dominated by the slip of partial dislocations enclosing\nthe stacking faults. At higher number of cycles, the grain boundary migration\nleading to coarsening of larger grains at the expense of the smaller grains has\nbeen observed. The cyclic stress-strain behaviour, the deformation mechanisms\nand the variation of dislocation density as a function of cyclic deformation\nhave been discussed."
    },
    {
        "anchor": "Near-Field Microwave Microscopy of Materials Properties: Near-field microwave microscopy has created the opportunity for a new class\nof electrodynamics experiments of materials. Freed from the constraints of\ntraditional microwave optics, experiments can be carried out at high spatial\nresolution over a broad frequency range. In addition, the measurements can be\ndone quantitatively so that images of microwave materials properties can be\ncreated. We review the five major types of near-field microwave microscopes and\ndiscuss our own form of microscopy in detail. Quantitative images of microwave\nsheet resistance, dielectric constant, and dielectric tunability are presented\nand discussed. Future prospects for near-field measurements of microwave\nelectrodynamic properties are also presented.",
        "positive": "A cohesive zone framework for environmentally assisted fatigue: We present a compelling finite element framework to model hydrogen assisted\nfatigue by means of a hydrogen- and cycle-dependent cohesive zone formulation.\nThe model builds upon: (i) appropriate environmental boundary conditions, (ii)\na coupled mechanical and hydrogen diffusion response, driven by chemical\npotential gradients, (iii) a mechanical behavior characterized by finite\ndeformation J2 plasticity, (iv) a phenomenological trapping model, (v) an\nirreversible cohesive zone formulation for fatigue, grounded on continuum\ndamage mechanics, and (vi) a traction-separation law dependent on hydrogen\ncoverage calculated from first principles. The computations show that the\npresent scheme appropriately captures the main experimental trends; namely, the\nsensitivity of fatigue crack growth rates to the loading frequency and the\nenvironment. The role of yield strength, work hardening, and constraint\nconditions in enhancing crack growth rates as a function of the frequency is\nthoroughly investigated. The results reveal the need to incorporate additional\nsources of stress elevation, such as gradient-enhanced dislocation hardening,\nto attain a quantitative agreement with the experiments."
    },
    {
        "anchor": "Exchange-enhanced Ultrastrong Magnon-Magnon Coupling in a Compensated\n  Ferrimagnet: The ultrastrong coupling of (quasi-)particles has gained considerable\nattention due to its application potential and richness of the underlying\nphysics. Coupling phenomena arising due to electromagnetic interactions are\nwell explored. In magnetically ordered systems, the quantum-mechanical\nexchange-interaction should furthermore enable a fundamentally different\ncoupling mechanism. Here, we report the observation of ultrastrong intralayer\nexchange-enhanced magnon-magnon coupling in a compensated ferrimagnet. We\nexperimentally study the spin dynamics in a gadolinium iron garnet single\ncrystal using broadband ferromagnetic resonance. Close to the ferrimagnetic\ncompensation temperature, we observe ultrastrong coupling of clockwise and\nanticlockwise magnon modes. The magnon-magnon coupling strength reaches more\nthan 30% of the mode frequency and can be tuned by varying the direction of the\nexternal magnetic field. We theoretically explain the observed phenomenon in\nterms of an exchange-enhanced mode-coupling mediated by a weak cubic\nanisotropy.",
        "positive": "Origin of interfacial perpendicular magnetic anisotropy in\n  MgO/CoFe/metallic capping layer structures: Spin-transfer-torque magnetic random access memory (STT-MRAM) attracts\nextensive attentions due to its non-volatility, high density and low power\nconsumption. The core device in STT-MRAM is CoFeB/MgO-based magnetic tunnel\njunction (MTJ), which possesses a high tunnel magnetoresistance ratio as well\nas a large value of perpendicular magnetic anisotropy (PMA). It has been\nexperimentally proven that a capping layer coating on CoFeB layer is essential\nto obtain a strong PMA. However, the physical mechanism of such effect remains\nunclear. In this paper, we investigate the origin of the PMA in\nMgO/CoFe/metallic capping layer structures by using a first-principles\ncomputation scheme. The trend of PMA variation with different capping materials\nagrees well with experimental results. We find that interfacial PMA in the\nthree-layer structures comes from both the MgO/CoFe and CoFe/capping layer\ninterfaces, which can be analyzed separately. Furthermore, the PMAs in the\nCoFe/capping layer interfaces are analyzed through resolving the magnetic\nanisotropy energy by layer and orbital. The variation of PMA with different\ncapping materials is attributed to the different hybridizations of both d and p\norbitals via spin-orbital coupling. This work can significantly benefit the\nresearch and development of nanoscale STT-MRAM."
    },
    {
        "anchor": "Phase-field crystal modelling of crystal nucleation, heteroepitaxy and\n  patterning: We apply a simple dynamical density functional theory, the\nphase-field-crystal (PFC) model, to describe homogeneous and heterogeneous\ncrystal nucleation in 2d monodisperse colloidal systems and crystal nucleation\nin highly compressed Fe liquid. External periodic potentials are used to\napproximate inert crystalline substrates in addressing heterogeneous\nnucleation. In agreement with experiments in 2d colloids, the PFC model\npredicts that in 2d supersaturated liquids, crystalline freezing starts with\nhomogeneous crystal nucleation without the occurrence of the hexatic phase. At\nextreme supersaturations crystal nucleation happens after the appearance of an\namorphous precursor phase both in 2d and 3d. We demonstrate that contrary to\nexpectations based on the classical nucleation theory, corners are not\nnecessarily favourable places for crystal nucleation. Finally, we show that\nadding external potential terms to the free energy, the PFC theory can be used\nto model colloid patterning experiments.",
        "positive": "Localized electromechanical interactions in ferroelectric P(VDF-TrFE)\n  nanowires investigated by scanning probe microscopy: We investigate the electromechanical interactions in individual P(VDF-TrFE)\nnanowires in response to localized electrical poling via a conducting atomic\nforce microscope tip. Spatially resolved measurements of piezoelectric\ncoefficients and elastic moduli before and after poling reveal a striking\ndependence on the polarity of the poling field, notably absent in thin films of\nthe same composition. These observations are attributed to the unclamped nature\nof the nanowires and the inherent asymmetry in their chemical and electrical\ninteractions with the tip and underlying substrate. Our findings provide\ninsights into the mechanism of poling/switching in polymer nanowires critical\nto ferroelectric device performance."
    },
    {
        "anchor": "Aperiodic compression and reconstruction of real world material systems\n  based on Wang tiles: The paper presents a concept/technique to compress and synthesize complex\nmaterial morphologies that is based on Wang tilings. Specifically, a\nmicrostructure is stored in a set of Wang tiles and its reconstruction is\nperformed by means of a stochastic tiling algorithm. A substantial part of the\nstudy is devoted to the setup of optimal parameters of the automatic tile\ndesign by means of parametric studies with statistical descriptors at heart.\nThe performance of the method is demonstrated on four two-dimensional two-phase\ntarget systems, monodisperse media with hard and soft discs, sandstone, and\nhigh porosity metallic foam.",
        "positive": "Structure and charge transport of amorphous $Cu$-doped $Ta_2O_5$ : An ab\n  initio study: In this paper, we present ab initio computer models of Cu-doped amorphous\nTa2O5 , a promising candidate for Conducting Bridge Random Access Memory\n(CBRAM) memory devices, and study the structural, electronic, charge transport\nand vibrational properties based on plane-wave density functional methods. We\noffer an atomistic picture of the process of phase segregation/separation\nbetween Cu and Ta2O5 subnetworks. Electronic calculations show that the models\nare conducting with extended Kohn-Sham orbitals around the Fermi level. In\naddition to that, we also characterize the electronic transport using the\nKubo-Greenwood formula modified suitably to calculate the space-projected\nconductivity (SPC). Our SPC calculations show that Cu clusters and\nunder-coordinated Ta adjoining the Cu are the conduction-active parts of the\nnetwork. We also report information about the dependence of the electrical\nconductivity on the connectivity of the Cu sub-matrix. Vibrational calculations\nfor one of the models has been undertaken with an emphasis on localization and\nanimation of representative modes."
    },
    {
        "anchor": "Thermodynamic stability of Fe/O solid solution at inner-core conditions: We present a new technique which allows the fully {\\em ab initio} calculation\nof the chemical potential of a substitutional impurity in a high-temperature\ncrystal, including harmonic and anharmonic lattice vibrations. The technique\nuses the combination of thermodynamic integration and reference models\ndeveloped recently for the {\\em ab initio} calculation of the free energy of\nliquids and anharmonic solids. We apply the technique to the case of the\nsubstitutional oxygen impurity in h.c.p. iron under Earth's core conditions,\nwhich earlier static {\\em ab initio} calculations indicated to be\nthermodynamically very unstable. Our results show that entropic effects arising\nfrom the large vibrational amplitude of the oxygen impurity give a major\nreduction of the oxygen chemical potential, so that oxygen dissolved in h.c.p.\niron may be stabilised at concentrations up a few mol % under core conditions.",
        "positive": "Strain-induced structure transformations on Si(111) and Ge(111)\n  surfaces: a combined density-functional and scannning tunnneling microscopy\n  report: Si(111) and Ge(111) surface formation energies were calculated using density\nfunctional theory for various biaxial strain states ranging from -0.04 to 0.04,\nand for a wide set of experimentally observed surface reconstructions: 3x3,\n5x5, 7x7 dimer-adatom-stacking fault reconstructions and c(2x8), 2x2 and\n\\sqrt{3}x\\sqrt{3} adatoms based surfaces. The calculations are compared with\nscanning tunneling microscopy data obtained on stepped Si(111) surfaces and on\nGe islands grown on a Si(111) substrate. It is shown that the surface structure\ntransformations observed in these strained systems are accounted for by a phase\ndiagram that relates the equilibrium surface structure to the applied strain.\nThe calculated formation energy of the unstrained Si(111)-9x9\ndimer-adatom-stacking fault surface is reported for the first time and it is\nhigher than corresponding energies of Si(111)-5x5 and Si(111)-7x7\ndimer-adatom-stacking fault surfaces as expected. We predict that the Si(111)\nsurface should adopt a c(2x8) reconstruction when tensile strain is above 0.03."
    },
    {
        "anchor": "Reconstruction of moir\u00e9 lattices in twisted transition metal\n  dichalcogenide bilayers: An important step in understanding the exotic electronic, vibrational, and\noptical properties of the moir\\'{e} lattices is the inclusion of the effects of\nstructural relaxation of the un-relaxed moir\\'{e} lattices. Here, we propose\nnovel structures for twisted bilayer of transition metal dichalcogenides\n(TMDs). For $\\theta\\gtrsim 58.4^{\\circ}$, we show a dramatic reconstruction of\nthe moir\\'{e} lattices, leading to a trimerization of the unfavorable\nstackings. We show that the development of curved domain walls due to the\nthree-fold symmetry of the stacking energy landscape is responsible for such\nlattice reconstruction. Furthermore, we show that the lattice reconstruction\nnotably changes the electronic band-structure. This includes the occurrence of\nflat bands near the edges of the conduction as well as valence bands, with the\nvalence band maximum, in particular, corresponding to localized states enclosed\nby the trimer. We also find possibilities for other complicated, entropy\nstabilized, lattice reconstructed structures.",
        "positive": "Black Phosphorus Mid-Infrared Photodetectors with High Gain: Recently, black phosphorus (BP) has joined the two dimensional material\nfamily as a promising candidate for photonic applications, due to its moderate\nbandgap, high carrier mobility, and compatibility with a diverse range of\nsubstrates. Photodetectors are probably the most explored BP photonic devices,\nhowever, their unique potential compared with other layered materials in the\nmid-infrared wavelength range has not been revealed. Here, we demonstrate BP\nmid infrared detectors at 3.39 um with high internal gain, resulting in an\nexternal responsivity of 82 A/W. Noise measurements show that such BP\nphotodetectors are capable of sensing low intensity mid-infrared light in the\npicowatt range. Moreover, the high photoresponse remains effective at kilohertz\nmodulation frequencies, because of the fast carrier dynamics arising from BPs\nmoderate bandgap. The high photoresponse at mid infrared wavelengths and the\nlarge dynamic bandwidth, together with its unique polarization dependent\nresponse induced by low crystalline symmetry, can be coalesced to promise\nphotonic applications such as chip-scale mid-infrared sensing and imaging at\nlow light levels."
    },
    {
        "anchor": "The effect of precipitation on strength and ductility in a Mg-Zn-Y alloy: The effect of pre-ageing deformation on the size and distribution of\nbeta-prime precipitates and subsequently on the resulting strength and\nductility have been measured in a Mg-3.0at.%Zn-0.5at.%Y alloy. The alloy was\nextruded and then subjected to a T8 heat treatment comprised of a\nsolution-treatment, cold-work and artificial ageing. Extrusion was used to\nintroduce texture, ensuring that deformation occurred via slip rather than\ntwinning. Samples were subjected to controlled uniaxial deformation and then\nisothermally aged to peak hardness. Precipitate length, diameter and number\ndensity were measured and evaluated in terms of the strength and ductility of\nthe alloy. The nucleation of the beta-prime precipitates in peak-aged condition\nwithout pre-ageing deformation (i.e.T6 treatment) was poor, with only 0.5%\nvolume fraction, compared to approximately 3.5% in T6 treated binary\nMg-3.0at.%Zn alloy. The microstructure of the Mg-Zn-Y alloy was less refined,\nwith larger diameter precipitates and lower beta-prime number densities\ncompared to a binary Mg-3.0at.%Zn alloy. Deformation to 5% plastic strain\nincreased the volume fraction of beta-prime precipitates to approximately 2.3%\nand refined the beta-prime precipitate length and diameter. The combination of\nthese effects increased the yield strength after isothermal ageing from 217MPa\n(0% cold-work) to 287 MPa (5% cold-work). The yield stress increased linearly\nwith reciprocal interparticle spacing on the basal and prismatic planes and the\nalloy showed similar strengthening against basal slip to Mg-Zn. The elongation\nincreased linearly with particle spacing. The ductility of Mg-Zn-Y alloys was\nsimilar to that of Mg-Zn for equivalently spaced particles.",
        "positive": "A synergistic view of magnetism, chemical activation, and ORR as well as\n  OER catalysis of carbon doped hexagonal boron nitride from first-principles: Carbon(C) doped hexagonal boron nitride(hBN) has been experimentally reported\nin recent years to be a possible catalytic host to oxygen reduction\nreaction(ORR), as well as a possible ferromagnet at room temperature.\nSubstitution by C in hBN has been also reported to form islands of graphene. In\nthis work, we explore from first principles, the connection between these\ndifferent aspects of C doped hBN. We find formation of graphene islands\ncovering unequal number of B and N sites in hBN to be energetically plausible.\nThey possess a net non-zero magnetic moment and are also found to be\nsubstantially more chemically active than their non-magnetic counterparts\ncovering equal number of B and N sites. On-site Coulomb repulsion between\nelectrons, known to be responsible for magnetism in bipartite lattices like\ngraphene and hBN, is also found to play a central role in chemical activation\nof not only the C atoms at the zigzag interface of magnetic graphene islands\nand hBN, but also of boron(B) sites in the immediate hBN neighborhood. However,\nsuch activated B or C due to substitution at B site, which is energetically\nmore favorable than at N site, has been reported to be unfavorable for ORR.\nAdvantageously, we find that the activation of C at B sites moderates\nsystematically with increasing size of graphene islands, paving the way for\nabundance of efficient catalytic sites at the edges of magnetic graphene\nislands covering more B sites than N sites. Accordingly, as an alternate to\nprecious metals for electrodes, we propose a class of graphene-hBN hybrids with\nlattices of magnetic graphene islands embedded in hBN, which can be metallic."
    },
    {
        "anchor": "AI-Aided Mapping of the Structure-Composition-Conductivity Relationships\n  of Glass-Ceramic Lithium Thiophosphate Electrolytes: Lithium thiophosphates (LPS) with the composition\n(Li$_2$S)$_x$(P$_2$S$_5$)$_{1-x}$ are among the most promising prospective\nelectrolyte materials for solid-state batteries (SSBs), owing to their\nsuperionic conductivity at room temperature ($>10^{-3}$ S cm$^{-1}$), soft\nmechanical properties, and low grain boundary resistance. Several glass-ceramic\n(gc) LPS with different compositions and good Li conductivity have been\npreviously reported, but the relationship between composition, atomic\nstructure, stability, and Li conductivity remains unclear due to the challenges\nin characterizing non-crystalline phases in experiments or simulations. Here,\nwe mapped the LPS phase diagram by combining first principles and artificial\nintelligence (AI) methods, integrating density functional theory, artificial\nneural network potentials, genetic-algorithm sampling, and ab initio molecular\ndynamics simulations. By means of an unsupervised structure-similarity\nanalysis, the glassy/ceramic phases were correlated with the local structural\nmotifs in the known LPS crystal structures, showing that the energetically most\nfavorable Li environment varies with the composition. Based on the discovered\ntrends in the LPS phase diagram, we propose a candidate solid-state electrolyte\ncomposition, (Li$_{2}$S)$_{x}$(P$_{2}$S$_{5}$)$_{1-x}$ ($x\\sim{}0.725$), that\nexhibits high ionic conductivity ($>10^{-2}$ S cm$^{-1}$) in our simulations,\nthereby demonstrating a general design strategy for amorphous or glassy/ceramic\nsolid electrolytes with enhanced conductivity and stability.",
        "positive": "Simultaneous existence of two spin-wave modes in ultrathin Fe/GaAs(001)\n  films studied by Brillouin Light Scattering: experiment and theory: A double-peaked structure was observed in the {\\it in-situ} Brillouin Light\nScattering (BLS) spectra of a 6 \\AA$ $ thick epitaxial Fe/GaAs(001) film for\nvalues of an external magnetic field $H$, applied along the hard in plane\ndirection, lower than a critical value $H_c\\simeq 0.9$ kOe. This experimental\nfinding is theoretically interpreted in terms of a model which assumes a\nnon-homogeneous magnetic ground state characterized by the presence of\nperperpendicular up/down stripe domains. For such a ground state, two spin-wave\nmodes, namely an acoustic and an optic mode, can exist. Upon increasing the\nfield the magnetization tilts in the film plane, and for $H \\ge H_{c}$ the\nground state is homogeneous, thus allowing the existence of just a single\nspin-wave mode. The frequencies of the two spin-wave modes were calculated and\nsuccessfully compared with the experimental data. The field dependence of the\nintensities of the corresponding two peaks that are present in the BLS spectra\nwas also estimated, providing further support to the above-mentioned\ninterpretation."
    },
    {
        "anchor": "Prediction of new multiferroic and magnetoelectric material Fe3Se4: Nowdays, multiferroic materials with magnetoelectric coupling have many\nreal-world applications in the fields of novel memory devices. It is\nchallenging is to create multiferroic materials with strongly coupled\nferroelectric and ferrimagnetic orderings at room temperature. The single\ncrystal of ferric selenide (Fe3Se4) shows type-II multiferroic due to the\ncoexistence of ferroelectric as well as magnetic ordering at room temperature.\nWe have investigated the lattice instability, electronic structure,\nferroelectric, ferrimagnetic ordering and transport properties of ferroelectric\nmetal Fe3Se4. The density of states shows considerable hybridization of Fe-3d\nand Se-4p states near the Fermi level confirming its metallic behavior. The\nmagnetic moments of Fe cations follow a type-II ferrimagnetic and ferroelectric\nordering with a calculated total magnetic moment of 4.25 per unit cell\n(Fe6Se8). The strong covalent bonding nature of Fe-Se leads to its\nferroelectric properties. In addition, the symmetry analysis suggests that\ntilting of Fe sub-lattice with 3d-t2g orbital ordering is due to the\nJahn-Teller (JT) distortion. This study provides further insight in the\ndevelopment of spintronics related technology using multiferroic materials.",
        "positive": "Mechanical detection and imaging of hyperbolic phonon polaritons in\n  hexagonal Boron Nitride: Mid-infrared nano-imaging and spectroscopy of two-dimensional (2D) materials\nhave been limited so far to scattering-type Scanning Near-field Optical\nMicroscopy (s-NSOM) experiments where light from the sample is scattered by a\nmetallic-coated Atomic Force Microscope (AFM) tip interacting with the material\nat the nanoscale. These experiments have recently allowed imaging of plasmon\npolaritons in graphene as well as hyperbolic phonon polaritons (HP2) in\nhexagonal Boron Nitride (hBN). Here we show that the high mechanical\nsensitivity of an AFM cantilever can be exploited for imaging hyperbolic phonon\npolaritons in hBN. In our imaging process, the lattice vibrations of hBN\nmicrometer-sized flakes are locally enhanced by the launched phonon polaritons.\nThese enhanced vibrations are coupled to the AFM tip in contact to the sample\nsurface and recorded during scanning. Imaging resolution better than\n{\\lambda}/20 is showed, comparable to the best resolution in s-NSOM.\nImportantly, this detection mechanism is free from light background and it is\nin fact the first photon-less detection of phonon polaritons."
    },
    {
        "anchor": "Fermi surface complexity, effective mass, and conduction band alignment\n  in n-type thermoelectric Mg3Sb2-xBix from first principles calculations: Using first principles calculations, we study the conduction band alignment,\neffective mass, and Fermi surface complexity factor of n-type Mg3Sb2-xBix (x =\n0, 1, and 2) from the full ab initio band structure. We find that with\nincreasing the Bi content the K and M band minima moves away from the\nconduction band minimum CB1 while the singly-degenerate $\\Gamma$ band minimum\nshifts rapidly downward and approaches the conduction band minimum. But the\nfavorable six-fold degenerate CB1 band minimum keeps dominating the conduction\nband minimum and there is no band crossing between the $\\Gamma$ and CB1 band\nminima. In addition, we show that the connection of the CB1 carrier pockets\nwith the energy level close to the band minimum M can strongly enhance the\ncarrier pocket anisotropy and Fermi surface complexity factor, which is likely\nthe electronic origin for the local maximum in the theoretical power factor.\nOur calculations also show that the band gap, density of states effective mass,\nSeebeck coefficient, and Fermi surface complexity factor decrease with\nincreasing the Bi content, which is unfavorable to the electrical transport.\nHowever, reducing the conductivity effective mass with increasing the Bi\ncontent is beneficial to the electrical transport by improving carrier mobility\nand weighted mobility as long as the detrimental bipolar effect is\ninsignificant. As a result, in comparison with n-type Mg3Sb2, n-type Mg3SbBi\nshows higher power factors and a much lower optimal carrier concentration for\nthe theoretical power factor at 300 K, which can be easily achieved by the\nexperiment.",
        "positive": "Quantifying magnetic anisotropy dispersion: Theoretical and experimental\n  study of the magnetic properties of anisotropic FeCuNbSiB ferromagnetic films: The Stoner-Wohlfarth model is a traditional and efficient tool to calculate\nmagnetization curves and it can provides further insights on the fundamental\nphysics associated to the magnetic properties and magnetization dynamics. Here,\nwe perform a theoretical and experimental investigation of the quasi-static\nmagnetic properties of anisotropic systems. We consider a theoretical approach\nwhich corresponds to a modified version of the Stoner-Wohlfarth model to\ndescribe anisotropic systems and a distribution function to express the\nmagnetic anistropy dispersion. We propose a procedure to calculate the magnetic\nproperties for the anisotropic case of the SW model from experimental results\nof the quadrature of magnetization curves, thus quantifying the magnetic\nanisotropy dispersion. To test the robustness of the approach, we apply the\ntheoretical model to describe the quasi-static magnetic properties of amorphous\nFeCuNbSiB ferromagnetic films. We perform calculations and directly compare\ntheoretical results with longitudinal and transverse magnetization curves\nmeasured for the films. Thus, our results provide experimental evidence to\nconfirm the validity of the theoretical approach to describe the magnetic\nproperties of anisotropic amorphous ferromagnetic films, revealed by the\nexcellent agreement between numerical calculation and experimental results."
    },
    {
        "anchor": "Quantum Transport in Metalporphyrins. An ab initio Green's function\n  approach to nanosensors design: An ab initio Green's function study of the electron transport properties of\nthe selected metal-porphyrin complexes has been performed. Transmission spectra\nand current-voltage dependence have been calculated for the porphyrin molecule\nlocated between gold electrodes in the presence of interaction with metal\natoms, which are most common in biochemistry (Fe(II), Fe(III), Mn(II), and\nZn(II)). It was shown that the estimated Fermi level almost coincides with the\nLUMO level of Fe(II)-porphyrin and Fe(III)-porphyrin, resulting in significant\nconductance at small voltage biases. Conductance of Mn(II)-porphyrin and\nZn(II)-porphyrin are much lower, and decrease from Mn to Zn. It was confirmed\nthat performing spin-unrestricted calculations is essential to account\nsplitting of the original molecular orbitals levels. Preformed calculations\ndemonstrate the principal possibility of experimental realization of porphyrin\nbased nanosensors.",
        "positive": "Crystal Plasticity for Dynamic Loading at High Pressures and Strains: A crystal plasticity theory was developed for use in simulations of dynamic\nloading at high pressures and strain rates. At pressures of the order of the\nbulk modulus, compressions o(100%) may be induced. At strain rates o(10^9)/s or\nhigher, elastic strains may reach o(10%), which may change the orientation of\nthe slip systems significantly with respect to the stress field. Elastic strain\nrather than stress was used in defining the local state, providing a more\ndirect connection with electronic structure predictions and consistency with\nthe treatment of compression in initial value problems in continuum dynamics.\nPlastic flow was treated through explicit slip systems, with flow on each\nsystem taken to occur by thermally-activated random jumps biased by the\nresolved stress. Compared with simple Arrhenius rates, the biased random jumps\ncaused significant differences in plastic strain rate as a function of\ntemperature and pressure, and provided a seamless transition to the ultimate\ntheoretical strength of the material. The behavior of the theory was\ninvestigated for matter with approximate properties for Ta, demonstrating the\nimportance of the high pressure, high strain rate contributions."
    },
    {
        "anchor": "Density functional theory study of experimentally observed Au/Ge\n  interfaces: In recent years, nanostructures with hexagonal polytypes of gold have been\nsynthesised, opening new possibilities in nanoscience and technology. As bulk\ngold crystallizes in the \\textit{fcc} phase, surface effects can play an\nimportant role in stabilizing hexagonal gold nanostructures. Here we\ninvestigate several hetero-structures with Ge substrate, including the\n\\textit{fcc} and \\textit{hcp} phases of gold that have been observed\nexperimentally. We determine and discuss their interfacial energies and\noptimized atomic arrangements, comparing the theory results with available\nexperimental data. Our calculations for the Au-\\textit{fcc}(011)/Ge(001) show\nhow the presence of defects in the interface layer can help to stabilize the\natomic pattern consistent with microscopic images. The Au-\\textit{hcp}/Ge\ninterface with the significant mismatch between two surfaces reveals large\natomic displacements, which might indicate that the (111) germanium substrate\nis not responsible for the formation of the \\textit{hcp} phase of gold.\nFinally, analyzing the electronic properties, we demonstrate that Au/Ge systems\nhave metallic character but covalent-like bonding states between interfacial Ge\nand Au atoms are also present.",
        "positive": "CO adsorption on metal surfaces: a hybrid functional study with plane\n  wave basis set: We present a detailed study of the adsorption of CO on Cu, Rh, and Pt (111)\nsurfaces in top and hollow sites. The study has been performed using the local\ndensity approximation, the gradient corrected functional PBE, and the hybrid\nHartree-Fock density functionals PBE0 and HSE03 within the framework of\ngeneralized Kohn-Sham density functional theory using a plane-wave basis set.\nAs expected, the LDA and GGA functionals show a tendency to favor the hollow\nsites, at variance with experimental findings that give the top site as the\nmost stable adsorption site. The PBE0 and HSE03 functionals reduce this\ntendency. In fact, they predict the correct adsorption site for Cu and Rh but\nfail for Pt. But even in this case, the hybrid functional destabilizes the\nhollow site by 50 meV compared to the PBE functional. The results of the total\nenergy calculations are presented along with an analysis of the projected\ndensity of states."
    },
    {
        "anchor": "Break of symmetry at the surface of IrTe$_2$ upon phase transition\n  measured by X-ray photoelectron diffraction: IrTe$_2$ undergoes a series of charge-ordered phase transitions below room\ntemperature that are characterized by the formation of stripes of Ir dimers of\ndifferent periodicities. Full hemispherical X-ray photoelectron diffraction\n(XPD) experiments have been performed to investigate the atomic position\nchanges undergone near the surface of $1T-$IrTe$_2$ in the first-order phase\ntransition, from the $(1\\times1)$ phase to the $(5\\times1)$ phase. Comparison\nbetween experiment and simulation allows us to identify the consequence of the\ndimerization on the Ir atoms local environment. We report that XPD permits to\nunveil the break of symmetry of IrTe$_2$ trigonal to a monoclonic unit cell and\nconfirm the occurence of the $(5\\times1)$ reconstruction within the first few\nlayers below the surface with a staircase-like stacking of dimers.",
        "positive": "Competing Hydrostatic Compression Mechanisms in Nickel Cyanide: We use variable-pressure neutron and X-ray diffraction measurements to\ndetermine the uniaxial and bulk compressibilities of nickel(II) cyanide,\nNi(CN)$_2$. Whereas other layered molecular framework materials are known to\nexhibit negative area compressibility, we find that Ni(CN)$_2$ does not. We\nattribute this difference to the existence of low-energy in-plane tilt modes\nthat provide a pressure-activated mechanism for layer contraction. The\nexperimental bulk modulus we measure is about four times lower than that\nreported elsewhere on the basis of density functional theory methods [{\\it\nPhys. Rev. B} {\\bf 83}, 024301 (2011)]."
    },
    {
        "anchor": "Electronic and vibrational Raman spectroscopy of\n  Nd$_{0.5}$Sr$_{0.5}$MnO$_3$ through the phase transitions: Raman scattering experiments have been carried out on single crystals of\nNd$_{0.5}$Sr$_{0.5}$MnO$_3$ as a function of temperature in the range of 320-50\nK, covering the paramagnetic insulator-ferromagnetc metal transition at 250 K\nand the charge-ordering antiferromagnetic transition at 150 K. The diffusive\nelectronic Raman scattering response is seen in the paramagnetic phase which\ncontinue to exist even in the ferromagnetic phase, eventually disappearing\nbelow 150 K. We understand the existence of diffusive response in the\nferromagnetic phase to the coexistence of the different electronic phases. The\nfrequency and linewidth of the phonons across the transitions show significant\nchanges, which cannot be accounted for only by anharmonic interactions.",
        "positive": "The Language of Hyperelastic Materials: The automated discovery of constitutive laws forms an emerging area that\nfocuses on automatically obtaining symbolic expressions describing the\nconstitutive behavior of solid materials from experimental data. Existing\nsymbolic/sparse regression methods rely on availability of libraries of\nmaterial models, which are typically hand-designed by a human expert relying on\nknown models as reference, or deploy generative algorithms with exponential\ncomplexity which are only practicable for very simple expressions. In this\npaper, we propose a novel approach to constitutive law discovery relying on\nformal grammars as an automated and systematic tool to generate constitutive\nlaw expressions complying with physics constraints. We deploy the approach for\ntwo tasks: i) Automatically generating a library of valid constitutive laws for\nhyperelastic isotropic materials; ii) Performing data-driven discovery of\nhyperelastic material models from displacement data affected by different noise\nlevels. For the task of automatic library generation, we demonstrate the\nflexibility and efficiency of the proposed methodology in alleviating\nhand-crafted features and human intervention. For the data-driven discovery\ntask, we demonstrate the accuracy, robustness and significant generalizability\nof the proposed methodology."
    },
    {
        "anchor": "Tuning the magnetic anisotropy and topological phase with electronic\n  correlation in single-layer H-FeBr$_2$: Electronic correlation can strongly influence the electronic properties of\ntwo-dimensional (2D) materials with open d- or f-orbitals. Herein, by taking\nsingle-layer (SL) H-FeBr$_2$ as a representative of the SL H-FeX$_2$ (X=Cl, Br,\nI) family, we investigated the electronic correlation effects in the magnetic\nanisotropy and electronic topology of such a system based on first-principles\ncalculations with DFT+\\textit{U} approach. Our result is that the magnetic\nanisotropy energy (MAE) of SL H-FeBr$_2$ shows a non-monotonic evolution\nbehaviour with increasing electronic correlation strength, which is mainly due\nto the competition between different element-resolved MAEs of Fe and Br.\nFurther investigations show that the evolution of element-resolved MAE arises\nfrom the variation of the spin-orbital coupling (SOC) interaction between\ndifferent orbitals in each atom. Moreover, tuning the strength of the\nelectronic correlation can drive the occurrence of band inversions, causing the\nsystem to undergoes multiple topological phase transitions, resulting in a\nquantum anomalous valley Hall (QAVH) effect. These exotic properties are\nuniversal for the SL H-FeX$_2$ (X = Cl, Br, I) family. Our work sheds light on\nthe role of electronic correlation effects in tuning magnetic and electronic\nstructures in the SL H-FeX$_2$ (X = Cl, Br, I) family, which could guide\nadvances in the development of new spintronics and valleytronics devices based\non these materials.",
        "positive": "Room-Temperature Silicon Band-Edge Photoluminescence Enhanced by\n  Spin-Coated Sol-Gel Films: Photoluminescence is observed at room temperature from phonon-assisted\nband-to-band emission in Si (1.067 eV peak) using unpatterned bulk p-type\nsilicon wafer samples that were spin-coated with Er-doped (6 at. %) silica-gel\nfilms (0.13 micron) and vacuum annealed; the strongest emission was obtained at\n~700 degrees C. Comparative study of annealing behavior indicates two-orders of\nmagnitude efficiency enhancement. Emission from Er+3 ions in the silica film is\nused to gauge relative emission strengths. Mechanisms for inducing emission\nfrom silicon utilizing stresses in sol-gel-films are discussed."
    },
    {
        "anchor": "Enhancement of the Anti-Damping Spin Torque Efficacy of Platinum by\n  Interface Modification: We report a strong enhancement of the efficacy of the spin Hall effect (SHE)\nof Pt for exerting anti-damping spin torque on an adjacent ferromagnetic layer\nby the insertion of $\\approx$ 0.5 nm layer of Hf between a Pt film and a thin,\n< 2 nm, Fe$_{60}$Co$_{20}$B$_{20}$ ferromagnetic layer. This enhancement is\nquantified by measurement of the switching current density when the\nferromagnetic layer is the free electrode in a magnetic tunnel junction. The\nresults are explained as the suppression of spin pumping through a substantial\ndecrease in the effective spin-mixing conductance of the interface, but without\na concomitant reduction of the ferromagnet\\' s absorption of the SHE generated\nspin current.",
        "positive": "On correctly assessing the reversibility of the magnetocaloric effect\n  from indirect measurements: The adiabatic temperature change ($\\Delta T_{ad}$) of a magnetic refrigerant\ncan be indirectly estimated through field ($H$) and temperature ($T$) dependent\nmagnetization ($M$) and specific heat ($C_p$) measurements. A direct\nintegration approach for this estimation is frequently reported, which is an\napproximation to a rigorous mathematical approach. In this work, we propose an\niterative method in small $H$ steps, to estimate $\\Delta T_{ad}$ from indirect\nmeasurements. We show that this approach is able to reproduce the reversibility\nof the magnetocaloric effect, and provides a more accurate estimation of\n$\\Delta T_{ad}$, up to 10\\% when considering a detailed $M(H,T)$ and $Cp(H,T)$\ndataset that reproduces the magnetothermal properties of gadolinium, a\nbenchmark room-temperature magnetic refrigerant."
    },
    {
        "anchor": "Top-down fabrication of atomic patterns in twisted bilayer graphene: Atomic-scale engineering typically involves bottom-up approaches, leveraging\nparameters such as temperature, partial pressures, and chemical affinity to\npromote spontaneous arrangement of atoms. These parameters are applied\nglobally, resulting in atomic scale features scattered probabilistically\nthroughout the material. In a top-down approach, different regions of the\nmaterial are exposed to different parameters resulting in structural changes\nvarying on the scale of the resolution. In this work, we combine the\napplication of global and local parameters in an aberration corrected scanning\ntransmission electron microscope (STEM) to demonstrate atomic scale precision\npatterning of atoms in twisted bilayer graphene. The focused electron beam is\nused to define attachment points for foreign atoms through the controlled\nejection of carbon atoms from the graphene lattice. The sample environment is\nstaged with nearby source materials, such that the sample temperature can\ninduce migration of the source atoms across the sample surface. Under these\nconditions, the electron-beam (top-down) enables carbon atoms in the graphene\nto be replaced spontaneously by diffusing adatoms (bottom-up). Using\nimage-based feedback-control, arbitrary patterns of atoms and atom clusters are\nattached to the twisted bilayer graphene with limited human interaction. The\nrole of substrate temperature on adatom and vacancy diffusion is explored by\nfirst-principles simulations.",
        "positive": "High-field magnetization and magnetoresistance of the $A$-site ordered\n  perovskite oxide CaCu$_{3}$Ti$_{4-x}$Ru$_{x}$O$_{12}$~($0 \\le x \\le 4$): We have measured high-field magnetization and magnetoresistance of\npolycrystalline samples of the A-site ordered perovskite CaCu3Ti4-xRuxO12 (x=0\n- 4) utilizing a non-destructive pulsed magnet. We find that the magnetization\nfor x=0.5, 1.0 and 1.5 is nonlinear, and tends to saturate in high fields. This\nis highly nontrivial because the magnetization for x=0 and 4 is linear in\nexternal field up to the highest one. We have analyzed this field dependence\nbased on the thermodynamics of magnetic materials, and propose that the\nexternal fields delocalize the holes on the Cu2+ ions in order to maximize the\nentropy. This scenario is qualitatively consistent with a large\nmagnetoresistance of -70% observed at 4.2 K at 52 T for x=1.5."
    },
    {
        "anchor": "Ultra-low lattice thermal conductivity in Cs2BiAgX6 (X=Cl, Br):\n  Potential thermoelectric materials: We have explored electronic and thermoelectric properties of bismuth-based\ndouble-perovskite halides Cs2BiAgX6 by using first principles calculations. The\ncalculated indirect bandgaps 2.85 eV and 1.99 eV for Cs2BiAgCl6 and Cs2BiAgBr6,\nrespectively well agree with the measured value (2.77 eV of Cs2BiAgCl6 and 2.19\neV of Cs2BiAgBr6). We have calculated the relaxation time and lattice thermal\nconductivity by using relaxation time approximation (RTA) within supercell\napproach. The lattice thermal conductivities for both compounds are remarkably\nlow and the obtained values at 300K for Cs2BiAgCl6 and Cs2BiAgBr6 are 0.078 and\n0.065 Wm-1K-1, respectively. Such quite low lattice thermal conductivity arises\ndue to low phonon group velocity in the large weighted phase space and large\nphonon scattering. The large Seebeck coefficient obtained for both halides at\n400K. We have obtained the maximum power factors at 700K and the corresponding\nthermoelectric figure of merit for Cs2BiAgCl6 and Cs2BiAgBr6 are 0.775 and\n0.774, respectively. The calculated results reveal that both halides are\npotential thermoelectric materials.",
        "positive": "Electrically-driven phase transition in magnetite nanostructures: Magnetite (Fe$_{3}$O$_{4}$), an archetypal transition metal oxide, has been\nused for thousands of years, from lodestones in primitive compasses[1] to a\ncandidate material for magnetoelectronic devices.[2] In 1939 Verwey[3] found\nthat bulk magnetite undergoes a transition at T$_{V}$ $\\approx$ 120 K from a\nhigh temperature \"bad metal\" conducting phase to a low-temperature insulating\nphase. He suggested[4] that high temperature conduction is via the fluctuating\nand correlated valences of the octahedral iron atoms, and that the transition\nis the onset of charge ordering upon cooling. The Verwey transition mechanism\nand the question of charge ordering remain highly controversial.[5-11] Here we\nshow that magnetite nanocrystals and single-crystal thin films exhibit an\nelectrically driven phase transition below the Verwey temperature. The\nsignature of this transition is the onset of sharp conductance switching in\nhigh electric fields, hysteretic in voltage. We demonstrate that this\ntransition is not due to local heating, but instead is due to the breakdown of\nthe correlated insulating state when driven out of equilibrium by electrical\nbias. We anticipate that further studies of this newly observed transition and\nits low-temperature conducting phase will shed light on how charge ordering and\nvibrational degrees of freedom determine the ground state of this important\ncompound."
    },
    {
        "anchor": "Non-Equilibrium Nature of Fracture Determines the Crack Paths: A high-fidelity neural network-based force field, NN-F$^{3}$, is developed to\ncover the strain states up to material failure and the non-equilibrium,\nintermediate nature of fracture. Simulations of fracture in 2D crystals using\nNN-F$^{3}$ reveal spatial complexities from lattice-scale kinks to sample-scale\npatterns. We find that the fracture resistance cannot be quantified by the\nenergy densities of relaxed edges as in the literature. Instead, the fracture\npatterns, critical stress intensity factors at the kinks, and energy densities\nof edges in the intermediate, unrelaxed states offer reasonable measures for\nthe fracture toughness and its anisotropy.",
        "positive": "Temperature Dependence of Self-diffusion in Cr2O3 from First Principles: Understanding and predicting the dominant diffusion processes in Cr2O3 is\nessential to its optimization for anti-corrosion coatings, spintronics, and\nother applications. Despite significant theoretical effort in modeling defect\nmediated diffusion in Cr2O3 the correlation with experimentally measured\ndiffusivities remains poor partly due to the insufficient accuracy of the\ntheoretical approaches. Here an attempt to resolve these discrepancies is made\nthrough high accuracy density functional theory simulations coupled with grand\ncanonical formalism of defect thermochemistry. In this approach, point defect\nformation energies were computed using hybrid exchange correlation functional.\nThis level of theory proved to be essential for achieving the agreement with\nexperimental self-diffusion coefficients. The analysis of the resulting\nself-diffusion coefficients indicate that chromium has higher mobility at low\ntemperatures and high oxygen partial pressures, in particular at standard\ntemperature and pressure conditions. At high vacuum, high temperature\nconditions, oxygen diffusion becomes dominant. At Cr/Cr2O3 interfaces O\nvacancies were found to be more mobile than Cr vacancies at all temperatures.\nCr diffuses preferentially along the c-axis at low temperatures but switches to\nbasal plane at higher temperatures. O diffusion is primarily bound to basal\nplane at all temperatures."
    },
    {
        "anchor": "Soft Magnetic Properties of Ultra-Strong and Nanocrystalline Pearlitic\n  Wires: The paper describes the capability of magnetic softening of a coarse grained\nbulk material by a severe deformation technique. Connecting the microstructure\nwith magnetic properties, the coercive field decreases dramatically for grains\nsmaller than the magnetic exchange length. This makes the investigation of soft\nmagnetic properties of severely drawn pearlitic wires very interesting. With\nthe help of the starting two phase microstructure, it is possible to\nsubstantially refine the material, which allows the investigation of magnetic\nproperties for nanocrystalline bulk material. Compared to the coarse grained\ninitial, pearlitic state, the coercivities of the highly deformed wires\ndecrease while the saturation magnetization values increase, even beyond the\nvalue expectable from the individual constituents. The lowest coercivity in the\ndrawn state is found to be 520 A m for a wire of 24 um thickness and an\nannealing treatment has a further positive effect on it. The decreasing\ncoercivity is discussed in the framework of two opposing models: grain\nrefinement on the one hand and dissolution of cementite on the other hand.\nAuxiliary measurements give a clear indication for the latter model, delivering\na sufficient description of the observed evolution of magnetic properties.",
        "positive": "Combinatorial Large-area MoS2/Anatase-TiO2 interface: A Pathway to\n  Emergent Optical and Opto-electronic Functionalities: Interface of transition metal dichalcogenide (TMDC) and high-k dielectric\ntransition metal oxides (TMO) had triggerred umpteen discourses due to the\nindubitable impact of TMO in reducing the contact resistances and restraining\nthe Fermi-level pinning for the metal-TMDC contacts. In the present work, we\nfocus on the unresolved tumults of large-area TMDC/TMO interfaces, grown by\nadopting different techniques. Here, on a pulsed laser deposited (PLD) MoS2\nthin film, a layer of TiO2 is grown by using both atomic layer deposition (ALD)\nand PLD. These two different techniques emanate TiO2 layers with different\ncrystalline properties, thicknesses and interfacial morphologies, subsequently\ninfluencing the electronic and optical properties of the interfaces. In\naddition, they manifest a boost in the extent of p-type doping with increasing\nthickness of TiO2, as emerged after analyzing the core-level shifts of the\nX-ray photoelectron spectra (XPS). Density functional analysis of the\nMoS2/Anatase-TiO2 interfaces, for pristine and in presence of a wide range of\ninterfacial defects, could explain the interdependence of doping and the\nterminating atomic-surface of TiO2 on MoS2. The optical properties of the\ninterface, encompassing the photoluminescence, transient absorption and z-scan\ntwo-photon absorption indicate the presence of defect-induced localized mid-gap\nlevels in MoS2/TiO2 (PLD), resulting quenched exciton signals. On the contrary,\nthe relatively defect-free interface in MoS2/TiO2 (ALD) demonstrates a clear\npresence of both A and B excitons of MoS2. From the investigation of optical\nproperties, we indicate that MoS2/TiO2 (PLD) interface may act as a promising\nsaturable absorber. Moreover, MoS2/TiO2 (PLD) interface had resulted a better\nphoto-transport. A potential application of MoS2/TiO2 (PLD) is demonstrated by\nthe fabrication of a p-type photo-transistor with the ionic-gel top gate."
    },
    {
        "anchor": "All-electron many-body approach to resonant inelastic x-ray scattering: We present a formalism for the resonant inelastic x-ray scattering (RIXS)\ncross section. The resulting compact expression in terms of polarizability\nmatrix elements, particularly lends itself to the implementation in an\nall-electron many-body perturbation theory (MBPT) framework, which is realized\nin the full-potential package exciting. With the carbon K edge RIXS of diamond\nand the oxygen K edge RIXS of $\\beta-\\mathrm{Ga_2 O_3}$, respectively, we\ndemonstrate the importance of electron-hole correlation and atomic coherence in\nthe RIXS spectra.",
        "positive": "Ab initio estimate of temperature dependence of electrical conductivity\n  in a model amorphous material: hydrogenated amorphous silicon: We present an ab initio calculation of the DC conductivity of amorphous\nsilicon and hydrogenated amorphous silicon. The Kubo-Greenwood formula is used\nto obtain the DC conductivity, by thermal averaging over extended dynamical\nsimulation. Its application to disordered solids is discussed. The conductivity\nis computed for a wide range of temperatures and doping is explored in a naive\nway by shifting the Fermi level. We observed the Meyer-Neldel rule for the\nelectrical conductivity with E_MNR = 0.06 eV and a temperature coefficient of\nresistance, TCR ~ -2.0% K^-1 for a-Si:H. In general, experimental trends are\nreproduced by these calculations, and this suggests the possible utility of the\napproach for modeling carrier transport in other disordered systems."
    },
    {
        "anchor": "Exchange biased Anomalous Hall Effect driven by frustration in a\n  magnetic Kagome lattice: Co3Sn2S2 is a ferromagnetic Weyl semimetal that has been the subject of\nintense scientific interest due to its large anomalous Hall effect. We show\nthat the coupling of this material's topological properties to its magnetic\ntexture leads to a strongly exchange biased anomalous Hall effect. We argue\nthat this is likely caused by the coexistence of ferromagnetism and spin glass\nphases, the latter being driven by the geometric frustration intrinsic to the\nKagome network of magnetic ions.",
        "positive": "Graphene allotropes: stability, structural and electronic properties\n  from DF-TB calculations: Using the density-functional-based tight-binding method we performed a\nsystematic comparative study of stability, structural and electronic properties\nfor 12 various types of graphene allotropes, which are likely candidates for\nengineering of novel graphene-like materials."
    },
    {
        "anchor": "Comment on \"Detection of Microwave Spin Pumping Using the Inverse Spin\n  Hall Effect\": A Comment on Phys. Rev. Lett. 111, 217204 (2013), \"Detection of Microwave\nSpin Pumping Using the Inverse Spin Hall Effect\"",
        "positive": "Interface Characteristics at an Organic/Metal Junction: Pentacene on Cu\n  Stepped Surfaces: The adsorption of pentacene on Cu(221), Cu(511) and Cu(911) is investigated\nusing density functional theory (DFT) with the self-consistent inclusion of van\nder Waals (vdW) interactions. Cu(211) is a vicinal of Cu(111) while Cu(511) and\n(911) are vicinals of Cu(100). For all the three surfaces, we found pentacene\nto prefer to adsorb parallel to the surface and near the steps. The addition of\nvdW interactions resulted in an enhancement in adsorption energies, with\nreference to the PBE functional, of around 2 eV. With vdWs inclusion, the\nadsorption energies were found to be 2.98 eV, 3.20 eV and 3.49 eV for Cu(211),\nCu(511) and Cu(911) respectively. These values reflect that pentacene adsorbs\nstronger on (100) terraces with a preference for larger terraces. The molecule\ntilts upon adsorption with a small tilt angle on the (100) vicinals (about a\nfew degrees) as compared to a large one on Cu(221) where the tilt angle is\nfound to be about 20o. We find that the adsorption results in a net charge\ntransfer to the molecule of ~1 electron, for all surfaces."
    },
    {
        "anchor": "Wireless magneto-ionics: voltage control of magnetism by bipolar\n  electrochemistry: Modulation of magnetic properties through voltage-driven ion motion and redox\nprocesses, i.e., magneto-ionics, is a unique approach to control magnetism with\nelectric field for low-power memory and spintronic applications. So far,\nmagneto-ionics has been achieved through direct electrical connections to the\nactuated material. Here we evidence that an alternative way to reach such\ncontrol exists in a wireless manner. Induced polarization in the conducting\nmaterial immersed in the electrolyte, without direct wire contact, promotes\nwireless bipolar electrochemistry, an alternative pathway to achieve\nvoltage-driven control of magnetism based on the same electrochemical processes\ninvolved in direct-contact magneto-ionics. A significant tunability of\nmagnetization is accomplished for cobalt nitride thin films, including\ntransitions between paramagnetic and ferromagnetic states. Such effects can be\neither volatile or non-volatile depending on the electrochemical cell\nconfiguration. These results represent a fundamental breakthrough that may\ninspire future device designs for applications in bioelectronics, catalysis,\nneuromorphic computing, or wireless communications.",
        "positive": "Influence of carbon and nitrogen on electronic structure and hyperfine\n  interactions in fcc iron-based alloys: Carbon and nitrogen austenites, modeled by Fe8N and Fe8C superstructures are\nstudied by full-potential LAPW method. Structure parameters, electronic and\nmagnetic properties as well as hyperfine interaction parameters are obtained.\nCalculations prove that Fe-C austenite can be successfully modeled by ordered\nFe8C superstructure. The results show that chemical Fe-C bond in Fe8C has\nhigher covalent part than in Fe8N. Detailed analysis of electric field gradient\nformation for both systems is performed. The calculation of electric field\ngradient allow us to carry out a good interpretation of Moessbauer spectra for\nFe-C and Fe-N systems."
    },
    {
        "anchor": "Mechanical coupling effects of 2D lattices uncovered by decoupled\n  micropolar elasticity tensor and symmetry operation: Mechanical couplings such as axial-shear and axial-bending have great\npotential in the design of active mechanical metamaterials with directional\ncontrol of input and output loads in sensors and actuators. However, the\ncurrent ad hoc design of mechanical coupling without theoretical support of\nelasticity cannot provide design guidelines for mechanical coupling with\nlattice geometries. Moreover, the correlation between mechanical coupling\neffects and geometric symmetry is not yet clearly understood. In this work, we\nsystematically search for all possible mechanical couplings in 2D lattice\nstructures by determining the non-zero diagonal terms in the decomposed\nmicropolar elasticity tensor. We also correlate the mechanical couplings with\nthe point-group symmetry of 2D lattices by applying the symmetry operation to\nthe decomposed micropolar elasticity tensor. The decoupled micropolar\nconstitutive equation uncovers eight coupling effects for 2D lattice\nstructures. The symmetry operation of the decoupled micropolar elasticity\ntensor reveals the correlation of the mechanical coupling with the point\ngroups. Our findings can strengthen the design of mechanical metamaterials with\npotential applications in areas including sensors, actuators, soft robots, and\nactive metamaterials for elastic/acoustic wave guidance and thermal management.",
        "positive": "Encapsulation Narrows Excitonic Homogeneous Linewidth of Exfoliated\n  MoSe$_2$ Monolayer: The excitonic homogeneous linewidth of an exfoliated monolayer MoSe$_2$\nencapsulated in hexagonal boron nitride is directly measured using\nmultidimensional coherent spectroscopy with micron spatial resolution. The\nlinewidth is 0.26 $\\pm$ 0.02 meV, corresponding to a dephasing time $T_2\n\\approx$ 2.5 ps, which is almost half the narrowest reported values for\nnon-encapsulated MoSe$_2$ flakes. We attribute the narrowed linewidth to\nCoulomb screening by the encapsulated material and suppression of non-radiative\nprocesses. Through direct measurements of encapsulated and non-encapsulated\nmonolayers, we confirm that encapsulation reduces the sample inhomogeneity.\nHowever, linewidths measured using photoluminescence and linear absorption\nremain dominated by inhomogeneity, and these linewidths are roughly 5 times\nlarger than the homogeneous linewidth in even the highest-quality encapsulated\nmaterials. The homogeneous linewidth of non-encapsulated monolayers is very\nsensitive to temperature cycling, whereas encapsulated samples are not modified\nby temperature cycling. The nonlinear signal intensity of non-encapsulated\nmonolayers is degraded by high-power optical excitation, whereas encapsulated\nsamples are very resilient to optical excitation with optical powers up to the\npoint of completely bleaching the exciton."
    },
    {
        "anchor": "Strain and thickness effects on magnetocrystalline anisotropy of\n  CoFe(011) films: We investigate MCA of CoFe(011) thin films as a function of strength of\nstrain and film thickness has been studied. It is elucidated that perpendicular\nmagnetocystalline anisotropy (MCA) energy (EMCA) is getting stronger with\ncompressed xy-plane lattice constant while in-plane MCA is become an easy-axis\nby tensile strain on xy-plane. The reason of the EMCA behaviors can be\nexplained by features of electronic structures.",
        "positive": "Materials under high pressure: A chemical perspective: At high pressure, the typical behavior of elements dictated by the periodic\ntable - including oxidation numbers, stoichiometries in compounds, and\nreactivity, to name but a few - is altered dramatically. As pressure is\napplied, the energetic ordering of atomic orbitals shifts, allowing core\norbitals to become chemically active, atypical electron configurations to\noccur, and in some cases, non-atom-centered orbitals to form in the interstices\nof solid structures. Strange stoichiometries, structures, and bonding motifs\nresult. Crystal structure prediction tools, not burdened by preconceived\nnotions about structural chemistry learned at atmospheric pressure, have been\napplied to great success to explore phase diagrams at high pressure,\nidentifying novel structures in diverse chemical systems. Several of these have\nbeen subsequently observed by experimental investigations, whose access to\nhigh-pressure regimes is bolstered by advances in diamond anvil cell and\ndynamic compression techniques. The joint efforts of experiment and theory have\nled to particular success in the realm of high-temperature superconductors,\nidentifying many novel phases whose superconducting transition approaches room\ntemperature."
    },
    {
        "anchor": "Compensated Ferrimagnets with Colossal Spin Splitting in Organic\n  Compounds: The study of the magnetic order has recently been invigorated by the\ndiscovery of exotic collinear antiferromagnets with time-reversal symmetry\nbreaking. Examples include altermagnetism and compensated ferrimagnets, which\nshow spin splittings of the electronic band structures even at zero net\nmagnetization, leading to several unique transport phenomena, notably\nspin-current generation. Altermagnets demonstrate anisotropic spin splitting,\nsuch as $d$-wave, in momentum space, whereas compensated ferrimagnets exhibit\nisotropic spin splitting. However, methods to realize compensated ferrimagnets\nare limited. Here, we demonstrate a method to realize a fully compensated\nferrimagnet with isotropic spin splitting utilizing the dimer structures\ninherent in organic compounds. Moreover, based on $ab$ $initio$ calculations,\nwe find that this ferrimagnet can be realized in the recently discovered\norganic compound (EDO-TTF-I)$_2$ClO$_4$. Our findings provide an unprecedented\nstrategy for using the dimer degrees of freedom in organic compounds to realize\nfully compensated ferrimagnets with colossal spin splitting.",
        "positive": "Electronic structure and weak itinerant magnetism in metallic Y2Ni7: We report a density functional study of the electronic structure and\nmagnetism of Y2Ni7. The results show itinerant magnetism very similar to that\nin the weak itinerant ferromagnet Ni3Al. The electropositive Y atoms in Y2Ni7\nserves to donate charge to the Ni host mostly in the form of $s$ electrons. The\nnon-spin-polarized state shows a high density of states at the Fermi level,\nN(EF) due to flat bands. This leads to the ferromagnetic instability. However,\nthere are also several much more dispersive bands crossing E(F), which should\npromote the conductivity. Spin fluctuation effects appear to be comparable to\nor weaker than Ni3Al, based on comparison with experimental data. Y2Ni7\nprovides a uniaxial analogue to cubic Ni3Al for studying weak itinerant\nferromagnetism, suggesting detailed measurements of its low temperature\nphysical properties and spin fluctuations, as well experiments under pressure."
    },
    {
        "anchor": "Observation of the Interlayer Exciton Gases in WSe$_2$ -p: WSe$_2$\n  Heterostructures: Interlayer excitons (IXs) possess a much longer lifetime than intralayer\nexcitons due to the spatial separation of the electrons and holes; hence, they\nhave been pursued to create exciton condensates for decades. The recent\nemergence of two-dimensional (2D) materials, such as transition metal\ndichalcogenides (TMDs), and of their van der Waals heterostructures (HSs), in\nwhich two different 2D materials are layered together, has created new\nopportunities to study IXs. Here we present the observation of IX gases within\ntwo stacked structures consisting of hBN/WSe$_2$/hBN/p: WSe$_2$/hBN. The IX\nenergy of the two different structures differed by 82 meV due to the different\nthickness of the hBN spacer layer between the TMD layers. We demonstrate that\nthe lifetime of the IXs is shortened when the temperature and the pump power\nincrease. We attribute this nonlinear behavior to an Auger process.",
        "positive": "Annealing-induced changes of the magnetic anisotropy of (Ga,Mn)As\n  epilayers: The dependence of the magnetic anisotropy of As-capped (Ga,Mn)As epilayers on\nthe annealing parameters - temperature and time - has been investigated. A\nuniaxial magnetic anisotropy is evidenced, whose orientation with respect to\nthe crystallographic axes changes upon annealing from [-110] for the as-grown\nsamples to [110] for the annealed samples. Both cubic an uniaxial anisotropies\nare tightly linked to the concentration of charge carriers, the magnitude of\nwhich is controlled by the annealing process."
    },
    {
        "anchor": "Scaling relation of the anomalous Hall effect in (Ga,Mn)As: We present magnetotransport studies performed on an extended set of (Ga,Mn)As\nsamples at 4.2 K with longitudinal conductivities sigma_{xx} ranging from the\nlow- to the high-conductivity regime. The anomalous Hall conductivity\nsigma_{xy}^(AH) is extracted from the measured longitudinal and Hall\nresistivities. A transition from sigma_{xy}^(AH)=20 Omega^{-1}cm^{-1} due to\nthe Berry phase effect in the high-conductivity regime to a scaling relation\nsigma_{xy}^(AH) proportional to sigma_{xx}^{1.6} for low-conductivity samples\nis observed. This scaling relation is consistent with a recently developed\nunified theory of the anomalous Hall effect in the framework of the Keldysh\nformalism. It turns out to be independent of crystallographic orientation,\ngrowth conditions, Mn concentration, and strain, and can therefore be\nconsidered universal for low-conductivity (Ga,Mn)As. The relation plays a\ncrucial role when deriving values of the hole concentration from\nmagnetotransport measurements in low-conductivity (Ga,Mn)As. In addition, the\nhole diffusion constants for the high-conductivity samples are determined from\nthe measured longitudinal conductivities.",
        "positive": "Temperature Dependence of Wavelength Selectable Zero-Phonon Emission\n  from Single Defects in Hexagonal Boron Nitride: We investigate the distribution and temperature-dependent optical properties\nof sharp, zero-phonon emission from defect-based single photon sources in\nmultilayer hexagonal boron nitride (h-BN) flakes. We observe sharp emission\nlines from optically active defects distributed across an energy range that\nexceeds 500 meV. Spectrally-resolved photon-correlation measurements verify\nsingle photon emission, even when multiple emission lines are simultaneously\nexcited within the same h-BN flake. We also present a detailed study of the\ntemperature-dependent linewidth, spectral energy shift, and intensity for two\ndifferent zero-phonon lines centered at 575 nm and 682 nm, which reveals a\nnearly identical temperature dependence despite a large difference in\ntransition energy. Our temperature-dependent results are best described by a\nlattice vibration model that considers piezoelectric coupling to in-plane\nphonons. Finally, polarization spectroscopy measurements suggest that whereas\nthe 575 nm emission line is directly excited by 532 nm excitation, the 682 nm\nline is excited indirectly."
    },
    {
        "anchor": "GaN:$\u03b4$-Mg grown by MOVPE: structural properties and their effect\n  on the electronic and optical behaviour: The effect of Mg $\\delta$-doping on the structural, electrical and optical\nproperties of GaN grown $\\textsl{via}$ metalorganic vapor phase epitaxy has\nbeen studied using transmission electron microscopy, secondary ion mass\nspectroscopy, atomic force microscopy, x-ray diffraction, Hall effect\nmeasurements and photoluminescence. For an average Mg concentration above 2.14\n$\\times$ 10$^{19}$ cm$^{-3}$, phase segregation occurs, as indicated by the\npresence of Mg-rich pyramidal inversion domains in the layers. We show that\n$\\delta$-doping promotes, in comparison to Mg continuous doping, the\nsuppression of extended defects on the samples surface and improves\nsignificantly the morphology of the epilayers. Conversely, we can not confirm\nthe reduction in the threading dislocation density - as a result of\n$\\delta$-doping - reported by other authors. In the phase separation regime,\nthe hole concentration is reduced with increasing Mg concentration, due to\nself-compensation mechanisms. Below the solubility limit of Mg into GaN at our\ngrowth conditions, potential fluctuations result in a red-shift of the emission\nenergy of the free-to-bound transition.",
        "positive": "Chemical Properties from Graph Neural Network-Predicted Electron\n  Densities: According to density functional theory, any chemical property can be inferred\nfrom the electron density, making it the most informative attribute of an\natomic structure. In this work, we demonstrate the use of established physical\nmethods to obtain important chemical properties from model-predicted electron\ndensities. We introduce graph neural network architectural choices that provide\nphysically relevant and useful electron density predictions. Despite not\ntraining to predict atomic charges, the model is able to predict atomic charges\nwith an order of magnitude lower error than a sum of atomic charge densities.\nSimilarly, the model predicts dipole moments with half the error of the sum of\natomic charge densities method. We demonstrate that larger data sets lead to\nmore useful predictions in these tasks. These results pave the way for an\nalternative path in atomistic machine learning, where data-driven approaches\nand existing physical methods are used in tandem to obtain a variety of\nchemical properties in an explainable and self-consistent manner."
    },
    {
        "anchor": "Shear Melting and High Temperature Embrittlement: Theory and Application\n  to Machining Titanium: We show that alloying with rare earth metals (REMs) can dramatically improve\nthe machineability of a range of titanium alloys, even though the REM is not\nincorporated in the alloy matrix. The mechanism for this is that under cutting,\nshear bands are formed within which the nano-precipitates of REM are shear\nmixed. This lowers the melting point such that the mechanism of deformation\nchanges from dislocation mechanism to localised amorphisation and shear\nsoftening. The material then fractures along the thin, amorphous shear-band.\nOutside the shear band, the REM remains as precipitates. The new alloys have\nsimilar mechanical properties and biocompatibility to conventional materials.",
        "positive": "Valency Configuration of Transition Metal Impurities in ZnO: We use the self-interaction corrected local spin-density approximation to\ninvestigate the ground state valency configuration of transition metal (TM =\nMn, Co) impurities in n- and p-type ZnO. We find that in pure Zn1-xTMxO, the\nlocalized TM2+ configuration is energetically favored over the itinerant\nd-electron configuration of the local spin density (LSD) picture. Our\ncalculations indicate furthermore that the (+/0) donor level is situated in the\nZnO gap. Consequently, for n-type conditions, with the Fermi energy eF close to\nthe conduction band minimum, TM remains in the 2+ charge state, while for\np-type conditions, with eF close to the valence band maximum, the 3+ charge\nstate is energetically preferred. In the latter scenario, modeled here by\nco-doping with N, the additional delocalized d-electron charge transfers into\nthe entire states at the top of the valence band, and hole carriers will only\nexist, if the N concentration exceeds the TM impurity concentration."
    },
    {
        "anchor": "Boundary Plane-Oriented Grain Boundary Model Generation: This study proposes algorithms for building tilt grain boundary (GB) models\nwith a boundary plane-oriented approach that does not rely on existence of a\ncoincidence site lattice (CSL). As conventional GB model generation uses the\nCSL of superimposed grains as the starting point, our totally different\napproach allows systematic treatment of diverse grain boundary systems that was\npreviously not possible. Candidates of a pair of GB planes for a selected\nrotation axis, constituting a symmetrical or asymmetrical tilt GB, are\nthoroughly obtained by computational search that is applicable to any crystal\nstructure. A GB interface for feasible computational analysis would have\ntwo-dimensional (2D) periodicity shared by the 2D lattices of the two GB\nplanes, hence surface-slab supercells (slab-and-vacuum models) with common\nin-plane basis vectors of the shared 2D lattice are obtained. Finally, a\nprocedure to obtain a GB-model supercell with alternately stacking such slabs\nis given. Symmetry operations of each slab may be considered such that the\niterated interfaces are symmetrically equivalent, which is beneficial in ab\ninitio calculations. The proposed algorithms allow streamlined generation of GB\nmodels, both symmetric and asymmetric, with or without an exact 3D-CSL\nrelation.",
        "positive": "Large and non-linear permeability amplification with polymeric additives\n  in hydrogel membranes: Hydrogels which are hydrophilic and porous materials have recently emerged as\npromising systems for filtration applications. In our study, we prepare\nhydrogel membranes by the photopolymerization of a mixture of poly (ethylene\nglycol) diacrylate (PEGDA) and large poly(ethylene glycol) (PEG) chains of 300\n000 g.mol-1 in the presence of a photoinitiator. We find that this addition of\nfree PEG chains induces a large and non-linear increase of the water\npermeability. Indeed, by changing the content of PEG chains added, we obtain\nvariations of the hydrogel water permeability over two orders of magnitude. The\nhighest water permeability values are obtained for the membranes when the PEG\nconcentration is equal to its critical overlap concentration C*. Moreover, we\nfind that the flow rate of water through the membranes varies non-linearly with\nthe pressure. We relate this result to the deformability of the membranes as\nthe applied pressure leads to a compression of the pores. This study provides\nnew perspectives for the design of flexible hydrogel membranes with controlled\npermeability and their application in water treatment and bioseparation."
    },
    {
        "anchor": "Multiscale analysis of crystal defect formation in rapid solidification\n  of pure aluminium and aluminium-copper alloys: Rapid solidification leads to unique microstructural features, where a less\nstudied topic is the formation of various crystalline defects, including high\ndislocation densities, as well as gradients and splitting of the crystalline\norientation. As these defects critically affect the material's mechanical\nproperties and performance features, it is important to understand the defect\nformation mechanisms, and how they depend on the solidification conditions and\nalloying. To illuminate the formation mechanisms of the rapid solidification\ninduced crystalline defects, we conduct a multiscale modeling analysis\nconsisting of bond-order potential based molecular dynamics (MD), phase field\ncrystal based amplitude expansion (PFC-AE) simulations, and sequentially\ncoupled phase field -- crystal plasticity (PF--CP) simulations. The resulting\ndislocation densities are quantified and compared to past experiments. The\natomistic approaches (MD, PFC) can be used to calibrate continuum level crystal\nplasticity models, and the framework adds mechanistic insights arising from the\nmultiscale analysis.",
        "positive": "Cubic silicon carbide under tensile pressure: Spinodal instability: Silicon carbide is a hard, semiconducting material presenting many polytypes,\nwhose behavior under extreme conditions of pressure and temperature has\nattracted large interest. Here we study the mechanical properties of 3C-SiC\nover a wide range of pressures (compressive and tensile) by means of molecular\ndynamics simulations, using an effective tight-binding Hamiltonian to describe\nthe interatomic interactions. The accuracy of this procedure has been checked\nby comparing results at T = 0 with those derived from ab-initio\ndensity-functional-theory calculations. This has allowed us to determine the\nmetastability limits of this material and in particular the spinodal point\n(where the bulk modulus vanishes) as a function of temperature. At T = 300 K,\nthe spinodal instability appears for a lattice parameter about 20% larger than\nthat corresponding to ambient pressure. At this temperature, we find a spinodal\npressure P_s = -43 GPa, which becomes less negative as temperature is raised\n(P_s = -37.9 GPa at 1500 K). These results pave the way for a deeper\nunderstanding of the behavior of crystalline semiconductors in a poorly known\nregion of their phase diagrams."
    },
    {
        "anchor": "Magnetic and dielectric properties of multiferroic Eu0.5Ba0.25Sr0.25TiO3\n  ceramics: Dielectric and magnetic properties of Eu0.5Ba0.25Sr0.25TiO3 are investigated\nbetween 10 K and 300 K in the frequency range from 10 Hz to 100 THz. A peak in\npermittivity revealed near 130 K and observed ferroelectric hysteresis loops\nprove the ferroelectric order below thistemperature. The peak in permittivity\nis given mainly by softening of the lowest frequency polar phonon (soft mode\nrevealed in THz and IR spectra) that demonstrates displacive character of the\nphase transition. Room-temperature X-ray diffraction analysis reveals cubic\nstructure, but the IR reflectivity spectra give evidence of a lower crystal\nstructure, presumably tetragonal I4/mcm with tilted oxygen octahedra as it has\nbeen observed in EuTiO3. The magnetic measurements show that the\nantiferromagnetic order occurs below 1.8 K. Eu0.5Ba0.25Sr0.25TiO3 has three\ntimes lower coercive field than Eu0.5Ba0.5TiO3, therefore we propose this\nsystem for measurements of electric dipole moment of electron.",
        "positive": "Theoretical analysis of the electronic structure of the stable and\n  metastable c(2x2) phases of Na on Al(001): Comparison with angle-resolved\n  ultra-violet photoemission spectra: Using Kohn-Sham wave functions and their energy levels obtained by\ndensity-functional-theory total-energy calculations, the electronic structure\nof the two c(2x2) phases of Na on Al(001) are analysed; namely, the metastable\nhollow-site structure formed when adsorption takes place at low temperature,\nand the stable substitutional structure appearing when the substrate is heated\nthereafter above ca. 180K or when adsorption takes place at room temperature\nfrom the beginning. The experimentally obtained two-dimensional band structures\nof the surface states or resonances are well reproduced by the calculations.\nWith the help of charge density maps it is found that in both phases, two\npronounced bands appear as the result of a characteristic coupling between the\nvalence-state band of a free c(2x2)-Na monolayer and the\nsurface-state/resonance band of the Al surfaces; that is, the clean (001)\nsurface for the metastable phase and the unstable, reconstructed \"vacancy\"\nstructure for the stable phase. The higher-lying band, being Na-derived,\nremains metallic for the unstable phase, whereas it lies completely above the\nFermi level for the stable phase, leading to the formation of a\nsurface-state/resonance band-structure resembling the bulk band-structure of an\nionic crystal."
    },
    {
        "anchor": "Electron energy-loss and inelastic X-ray scattering cross sections from\n  time-dependent density-functional perturbation theory: The Liouville-Lanczos approach to linear-response time-dependent\ndensity-functional theory is generalized so as to encompass electron\nenergy-loss and inelastic X-ray scattering spectroscopies in periodic solids.\nThe computation of virtual orbitals and the manipulation of large matrices are\navoided by adopting a representation of response orbitals borrowed from\n(time-independent) density-functional perturbation theory and a suitable\nLanczos recursion scheme. The latter allows the bulk of the numerical work to\nbe performed at any given transferred momentum only once, for a whole extended\nfrequency range. The numerical complexity of the method is thus greatly\nreduced, making the computation of the loss function over a wide frequency\nrange at any given transferred momentum only slightly more expensive than a\nsingle standard ground-state calculation, and opening the way to computations\nfor systems of unprecedented size and complexity. Our method is validated on\nthe paradigmatic examples of bulk silicon and aluminum, for which both\nexperimental and theoretical results already exist in the literature.",
        "positive": "Room-temperature spin transport in n-Ge probed by four-terminal nonlocal\n  measurements: We demonsrtate electrical spin injection and detection in $n$-type Ge\n($n$-Ge) at room temperature using four-terminal nonlocal spin-valve and\nHanle-effect measurements in lateral spin-valve (LSV) devices with\nHeusler-alloy Schottky tunnel contacts. The spin diffusion length\n($\\lambda$$_{\\rm Ge}$) of the Ge layer used ($n \\sim$ 1 $\\times$ 10$^{19}$\ncm$^{-3}$) at 296 K is estimated to be $\\sim$ 0.44 $\\pm$ 0.02 $\\mu$m.\nRoom-temperature spin signals can be observed reproducibly at the low bias\nvoltage range ($\\le$ 0.7 V) for LSVs with relatively low resistance-area\nproduct ($RA$) values ($\\le$ 1 k$\\Omega$$\\mu$m$^{2}$). This means that the\nSchottky tunnel contacts used here are more suitable than ferromagnet/MgO\ntunnel contacts ($RA \\ge$ 100 k$\\Omega$$\\mu$m$^{2}$) for developing Ge\nspintronic applications."
    },
    {
        "anchor": "Current-driven dynamics of antiferromagnetic skyrmions: from skyrmion\n  Hall effects to hybrid inter-skyrmion scattering: Antiferromagnetic (AFM) skyrmions have emerged as a highly promising avenue\nin the realm of spintronics, particularly for the development of advanced\nracetrack memory devices. A distinguishing feature of AFM skyrmions is their\nzero topological charge and hence anticipated zero skyrmion Hall effect (SkHE).\nHere, we unveil that the latter is surprisingly finite under the influence of\nspin-transfer torque, depending on the direction of the injected current\nimpinging on intrinsic AFM skyrmions emerging in CrPdFe trilayer on Ir(111)\nsurface. Hinging on first-principles combined with atomistic spin dynamics\nsimulations, we identify the origin of the SkHE and uncover that FM skyrmions\nin the underlying Fe layer act as effective traps for AFM skyrmions, confining\nthem and reducing their velocity. These findings hold significant promise for\nspintronic applications, the design of multi-purpose skyrmion-tracks, advancing\nour understanding of AFM-FM skyrmion interactions and hybrid soliton dynamics\nin heterostructures.",
        "positive": "Structural evidence for ultrafast polarization rotation in\n  ferroelectric/dielectric superlattice nanodomains: Weakly coupled ferroelectric/dielectric superlattice thin film\nheterostructures exhibit complex nanoscale polarization configurations that\narise from a balance of competing electrostatic, elastic, and domain-wall\ncontributions to the free energy. A key feature of these configurations is that\nthe polarization can locally have a significant component that is not along the\nthin-film surface normal direction, while maintaining zero net in-plane\npolarization. PbTiO3/SrTiO3 thin-film superlattice heterostructures on a\nconducting SrRuO3 bottom electrode on SrTiO3 have a room-temperature stripe\nnanodomain pattern with nanometer-scale lateral period. Ultrafast time-resolved\nx-ray free electron laser diffraction and scattering experiments reveal that\nabove-bandgap optical pulses induce rapidly propagating acoustic pulses and a\nperturbation of the domain diffuse scattering intensity arising from the\nnanoscale stripe domain configuration. With 400 nm optical excitation, two\nseparate acoustic pulses are observed: a high-amplitude pulse resulting from\nstrong optical absorption in the bottom electrode and a weaker pulse arising\nfrom the depolarization field screening effect due to absorption directly\nwithin the superlattice. The picosecond scale variation of the nanodomain\ndiffuse scattering intensity is consistent with a larger polarization change\nthan would be expected due to the polarization-tetragonality coupling of\nuniformly polarized ferroelectrics. The polarization change is consistent\ninstead with polarization rotation facilitated by the reorientation of the\nin-plane component of the polarization at the domain boundaries of the striped\npolarization structure. The complex steady-state configuration within these\nferroelectric heterostructures leads to polarization rotation phenomena that\nhave been previously available only through the selection of bulk crystal\ncomposition."
    },
    {
        "anchor": "Effect of phonon anharmonicity on ferroelectricity in EuxBa1-xTiO3: Investigating the competition between ferroelectric ordering and quantum\nfluctuations is essential to tailor the desired functionalities of mixed\nferroelectric and incipient ferroelectric systems, like, (Ba,Sr)TiO3 and\n(Eu,Ba)TiO3. Recently, it has been shown that suppression of quantum\nfluctuations increases ferroelectric ordering in (Eu,Ba)TiO3 and since these\nphenomena are coupled to crystallographic phase transitions it is essential to\nunderstand the role of phonons. Here, we observe that the unusual temperature\ndependence of phonons in BaTiO3 gets suppressed when Ba2+ is replaced by Eu2+.\nThis manifests in a decrease in the cubic-to-tetragonal (i.e.,\npara-to-ferroelectric) phase transition temperature (by 150 K) and a complete\nsuppression of tetragonality of the lattice (at room temperature by 40%\nreplacement of Ba2+ by Eu2+). We have quantified the anharmonicity of the\nphonons and observed that the replacement of Ba2+ by Eu2+ suppresses it (by\n93%) with a resultant lowering of the ferroelectric ordering temperature in the\nEuxBa1-xTiO3. This suggests that tuning phonon anharmonicity can be an\nimportant route to novel ferroelectric materials.",
        "positive": "Ultra-fast Vacancy Migration: A Novel Approach for Synthesizing Sub-10\n  nm Crystalline Transition Metal Dichalcogenide Nanocrystals: Two-dimensional materials, such as transition metal dichalcogenides (TMDCs),\nhave the potential to revolutionize the field of electronics and photonics due\nto their unique physical and structural properties. This research presents a\nnovel method for synthesizing crystalline TMDCs crystals with < 10 nm size\nusing ultra-fast migration of vacancies at elevated temperatures. Through\nin-situ and ex-situ processing and using atomic-level characterization\ntechniques, we analyze the shape, size, crystallinity, composition, and strain\ndistribution of these nanocrystals. These nanocrystals exhibit electronic\nstructure signatures that differ from the 2D bulk i.e., uniform mono and\nmultilayers. Further, our in-situ, vacuum-based synthesis technique allows\nobservation and comparison of defect and phase evolution in these crystals\nformed under van der Waals heterostructure confinement versus unconfined\nconditions. Overall, this research demonstrates a solid-state route to\nsynthesizing uniform nanocrystals of TMDCs and lays the foundation for\nmaterials science in confined 2D spaces under extreme conditions."
    },
    {
        "anchor": "Deformation induced pseudo-magnetic fields in complex carbon\n  architectures: We show that the physics of deformation in $\\alpha$-, $\\beta$-, and\n$6,6,12$-graphyne is, despite their significantly more complex lattice\nstructures, remarkably close to that of graphene, with inhomogeneously strained\ngraphyne described at low energies by an emergent Dirac-Weyl equation augmented\nby strain induced electric and pseudo-magnetic fields. To show this we develop\ntwo continuum theories of deformation in these materials: one that describes\nthe low energy degrees of freedom of the conical intersection, and is spinor\nvalued as in graphene, and one describing the full sub-lattice space. The\nspinor valued continuum theory agrees very well with the full continuum theory\nat low energies, showing that the remarkable physics of deformation in graphene\ngeneralizes to these more complex carbon architectures. In particular, we find\nthat deformation induced pseudospin polarization and valley current loops, key\nphenomena in the deformation physics of graphene, both have their counterpart\nin these more complex carbon materials.",
        "positive": "Theory of strains in auxetic materials: Auxetic materials, or negative-Poisson's-ratio materials, are important\ntechnologically and fascinating theoretically. When loaded by external\nstresses, their internal strains are governed by correlated motion of internal\nstructural degrees of freedom. The modelling of such materials is mainly based\non ordered structures, despite existence of auxetic behaviour in disordered\nstructures and the advantage in manufacturing disordered structures for most\napplications. We describe here a first-principles expression for strains in\ndisordered such materials, based on insight from a family of 'iso-auxetic'\nstructures. These are structures, consisting of internal structural elements,\nwhich we name 'auxetons', whose inter-element forces can be computed from\nstatics alone. Iso-auxetic structures make it possible not only to identify the\nmechanisms that give rise to auxeticity, but also to write down the explicit\ndependence of the strain rate on the local structure, which is valid to all\nauxetic materials. It is argued that stresses give rise to strains via two\nmechanisms: auxeton rotations and auxeton expansion / contraction. The former\ndepends on the stress via a local fabric tensor, which we define explicitly for\n2D systems. The latter depends on the stress via an expansion tensor. Whether a\nmaterial exhibits auxetic behaviour or not depends on the interplay between\nthese two fields. This description has two major advantages: it applies to any\nauxeton-based system, however disordered, and it goes beyond conventional\nelasticity theory, providing an explicit expression for general auxetic strains\nand outlining the relevant equations."
    },
    {
        "anchor": "Photoelectric absorption cross section of silicon near the band gap from\n  room temperature to sub-Kelvin temperature: The use of cryogenic silicon as a detector medium for dark matter searches is\ngaining popularity. Many of these searches are highly dependent on the value of\nthe photoelectric absorption cross section of silicon at low temperatures,\nparticularly near the silicon band gap energy, where the searches are most\nsensitive to low mass dark matter candidates. While such cross section data has\nbeen lacking from the literature, previous dark matter search experiments have\nattempted to estimate this parameter by extrapolating it from higher\ntemperature data. However, discrepancies in the high temperature data have led\nto order-of-magnitude differences in the extrapolations. In this paper, we\nresolve these discrepancies by using a novel technique to make a direct, low\ntemperature measurement of the photoelectric absorption cross section of\nsilicon at energies near the band gap.",
        "positive": "Structural, elastic, electronic, and bonding properties of intermetallic\n  Nb3Pt and Nb3Os compounds: a DFT study: Theoretical investigation of structural, elastic, electronic and bonding\nproperties of A-15 Nb-based intermetallic compounds Nb3B (B = Pt, Os) have been\nperformed using first principles calculations based on the density functional\ntheory (DFT). Optimized cell parameters are found to be in good agreement with\navailable experimental and theoretical results. The elastic constants at zero\npressure and temperature are calculated and the anisotropic behaviors of the\ncompounds are studied. Both the compounds are mechanically stable and ductile\nin nature. Other elastic properties such as Pugh's ratio, Cauchy pressure,\nmachinability index are derived for the first time. Nb3Os is expected to have\ngood lubricating properties compared to Nb3Pt. The electronic band structure\nand energy density of states (DOS) have been studied with and without\nspin-orbit coupling (SOC). The band structures of both the compounds are spin\nsymmetric. Electronic band structure and DOS reveal that both the compounds are\nmetallic and the conductivity mainly arise from the Nb 4d states. The Fermi\nsurface features have been studied for the first time. The Fermi surfaces of\nNb3B contain both hole- and electron-like sheets which change as one replaces\nPt with Os. The electronic charge density distribution shows that Nb3Pt and\nNb3Os both have a mixture of ionic and covalent bonding. The charge transfer\nbetween atomic species in these compounds has been explained by the Mulliken\nbond population analysis."
    },
    {
        "anchor": "Pattern Learning Electronic Density of States: Electronic density of states (DOS) is a key factor in condensed matter\nphysics and material science that determines the properties of metals.\nFirst-principles density-functional theory (DFT) calculations have typically\nbeen used to obtain the DOS despite the considerable computation cost. Herein,\nwe report a fast pattern learning method for predicting the DOS patterns of not\nonly bulk structures but also surface structures in multi-component alloy\nsystems by a principal component analysis. Within this framework, we use only\nfour features to define the composition, atomic structure, and surfaces of\nalloys, which are the d-orbital occupation ratio, coordination number, mixing\nfactor, and the inverse of miller indices. While the DFT method scales as\nO(N^3) in which N is the number of electrons in the system size, our pattern\nlearning method can scale as O(1) regardless of N. Furthermore, our method\nprovides a pattern similarity of 91~98% compared to DFT calculations. This\nreveals that our learning method will be an alternative that can break the\ntrade-off relationship between accuracy and speed that is well known in the\nfield of electronic structure calculations.",
        "positive": "Resolving hydrogen atoms at metal-metal hydride interfaces: Hydrogen as a fuel can be stored safely with high volumetric density in\nmetals. It can, however, also be detrimental to metals causing embrittlement.\nUnderstanding fundamental behavior of hydrogen at atomic scale is key to\nimprove the properties of metal-metal hydride systems. However, currently,\nthere is no robust technique capable of visualizing hydrogen atoms. Here, we\ndemonstrate that hydrogen atoms can be imaged unprecedentedly with integrated\ndifferential phase contrast, a recently developed technique performed in a\nscanning transmission electron microscope. Images of the titanium-titanium\nmonohydride interface reveal remarkable stability of the hydride phase,\noriginating from the interplay between compressive stress and interfacial\ncoherence. We also uncovered, thirty years after three models were proposed,\nwhich one describes the position of the hydrogen atoms with respect to the\ninterface. Our work enables novel research on hydrides and is extendable to all\nmaterials containing light and heavy elements, including oxides, nitrides,\ncarbides and borides."
    },
    {
        "anchor": "Structured electrode additive manufacturing for lithium-ion batteries: A thick electrode with high areal capacity has been developed as a strategy\nfor high-energy-density lithium-ion batteries, but thick electrodes have\ndifficulties in manufacturing and limitations in ion transport. Here, we\nreported a new manufacturing approach for ultra-thick electrode with aligned\nstructure, called structure electrode additive manufacturing or SEAM, which\naligns active materials to the through-thicknesses direction of electrodes\nusing shear flow and a designed printing path. The ultra-thick electrodes with\nhigh loading of active materials, low tortuous structure, and good structure\nstability resulting from a simple and scalable SEAM lead to rapid ion transport\nand fast electrolyte infusion, delivering a higher areal capacity than\nslurry-casted thick electrodes. SEAM shows strengths in design flexibility and\nscalability, which allows the production of practical high energy/power density\nstructure electrodes.",
        "positive": "Intrinsic dissipation mechanisms in metallic glass resonators: Micro- and nano-resonators have important applications including sensing,\nnavigation, and biochemical detection. Their performance is quantified using\nthe quality factor $Q$, which gives the ratio of the energy stored to the\nenergy dissipated per cycle. Metallic glasses are a promising materials class\nfor micro- and nano-scale resonators since they are amorphous and can be\nfabricated precisely into complex shapes on these lengthscales. To understand\nthe intrinsic dissipation mechanisms that ultimately limit large $Q$-values in\nmetallic glasses, we perform molecular dynamics simulations to model metallic\nglass resonators subjected to bending vibrations. We calculate the vibrational\ndensity of states, redistribution of energy from the fundamental mode of\nvibration, and $Q$ versus the kinetic energy per atom $K$ of the excitation. In\nthe linear and nonlinear response regimes where there are no atomic\nrearrangements, we find that $Q \\rightarrow \\infty$ (since we do not consider\ncoupling to the environment). We identify a characteristic $K_r$ above which\natomic rearrangements occur, and there is significant energy leakage from the\nfundamental mode to higher frequencies, causing finite $Q$. Thus, $K_r$ is a\ncritical parameter determining resonator performance. We show that $K_r$\ndecreases as a power-law, $K_r\\sim N^{-k},$ with increasing system size $N$,\nwhere $k \\approx 1.3$. We estimate the critical strain $\\langle \\gamma_r\n\\rangle \\sim 10^{-8}$ for micron-sized resonators below which atomic\nrearrangements do not occur, and thus large $Q$-values can be obtained when\nthey are operated below $\\gamma_r$. We find that $K_r$ for amorphous resonators\nis comparable to that for resonators with crystalline order."
    },
    {
        "anchor": "Formation of transition metal hydrides at high pressures: Silane (SiH4) is found to (partially) decompose at pressures above 50 GPa at\nroom temperature into pure Si and H2. The released hydrogen reacts with\nsurrounding metals in the diamond anvil cell to form metal hydrides. A\nformation of rhenium hydride is observed after the decomposition of silane.\n  From the data of a previous experimental report (Eremets et al., Science 319,\n1506 (2008)), the claimed high-pressure metallic and superconducting phase of\nsilane is identified as platinum hydride, that forms after the decomposition of\nsilane. These observations show the importance of taking into account possible\nchemical reactions that are often neglected in high-pressure experiments.",
        "positive": "Effect of powder bed fusion process parameters on microstructural and\n  mechanical properties of FeCrNi MEA: An atomistic study: In our study, molecular dynamics (MD) simulations of laser powder bed fusion\n(LPBF) have been conducted on equimolar FeNiCr medium entropy alloy (MEA)\npowders. With the development of newer LPBF technologies capable of printing at\nthe microscale, an even deeper understanding of the underlying atomistic\neffects of the process parameters on the microstructural and mechanical\nproperties of the manufactured FeNiCr MEA products is required. In accordance\nwith previous literature, the parameters of the LPBF process have been\nsystematically varied, including layer resolution from 1 to 6, laser power from\n100 {\\mu}W to 220 {\\mu}W, bed temperature from 300 K to 1200 K, and laser scan\nspeed from 0.5 {\\AA}/ps to 0.0625 {\\AA}/ps. Consistent with prior macroscopic\nexperimental findings, the atomistic results suggest that additive\nmanufacturing using thinner layers imparts higher ultimate tensile strength\n(UTS) than fabricating with thicker layers. The latter, however, requires a\nshorter process time but induces keyhole defect formation if the laser-induced\ntemperature is not sufficiently high enough. Increasing the temperature proves\nuseful in mitigating this problem. Enhancement of UTS for the multi-rowed\npowders has been observed by raising the substrate temperature to 600 K or\nlaser power to 160 {\\mu}W during production. Beyond these critical limits,\nhowever, the UTS of the product diminishes due to the emergence of multiple\nvacancies. The results of our present study will help researchers to find a\ngood balance between the production speed and strength of additive manufactured\nproducts at the nanoscale."
    },
    {
        "anchor": "Phases and magnetism at the microscale in compounds containing nominal\n  Pb10-xCux(PO4)6O: Achieving superconductivity at room temperature could lead to substantial\nadvancements in industry and technology. Recently, a compound known as Cu-doped\nlead-apatite, Pb10-xCux(PO4)6O (0.9 < x < 1.1), referred to as \"LK-99\", has\nbeen reported to exhibit unusual electrical and magnetic behaviors that appear\nto resemble a superconducting transition above room temperature. In this work\nwe collected multiphase samples containing the nominal Pb10-xCux(PO4)6O phase\n(no superconductivity observed in our measured samples), synthesized by three\nindependent groups, and studied their chemical, magnetic, and electrical\nproperties at the microscale to overcome difficulties in bulk measurements.\nThrough the utilization of optical, scanning electron, atomic force, and\nscanning diamond nitrogen-vacancy microscopy techniques, we are able to\nestablish a link between local magnetic properties and specific microscale\nchemical phases. Our findings indicate that while the Pb10-xCux(PO4)6O phase\nseems to have a mixed magnetism contribution, a significant fraction of the\ndiamagnetic response can be attributed to Cu-rich regions (e.g., Cu2S derived\nfrom a reagent used in the synthesis). Additionally, our electrical\nmeasurements reveal the phenomenon of current path switch and a change in\nresistance states of Cu2S. This provides a potential explanation for the\nelectrical behavior observed in compounds related to Pb10-xCux(PO4)6O.",
        "positive": "Magnon properties of random alloys: We study magnon properties in terms of spin stiffness, Curie temperatures and\nmagnon spectrum of Fe-Ni, Co-Ni and Fe-Co random alloys using a combination of\nelectronic structure calculations and atomistic spin dynamics simulations.\nInfluence of the disorder are studied in detail by use of large supercells with\nrandom atomic arrangement. It is found that disorder affects the magnon\nspectrum in vastly different ways depending on the system. Specifically, it is\nmore pronounced in Fe-Ni alloys compared to Fe-Co alloys. In particular, the\nmagnon spectrum at room temperature in Permalloy (Fe$_{20}$Ni$_{80}$) is found\nto be rather diffuse in a large energy interval while in Fe$_{75}$Co$_{25}$ it\nforms sharp branches. Fe-Co alloys are very interesting from a technological\npoint of view due to the combination of large Curie temperatures and very low\ncalculated Gilbert damping of $\\sim$0.0007 at room temperature for Co\nconcentrations around 20--30\\%."
    },
    {
        "anchor": "Anomalous Zeeman effect in SrTiO3 and its possible all-electric\n  detection: We show that the interplay between spin-orbit coupling and cubic symmetry\nbreaking in SrTiO3 results in a highly anomalous Zeeman effect of conduction\nelectrons substantially different among the three conduction sub-bands and\nstrongly dependent on their splitting. This effect can be measured via\nelectrically-driven spin resonance enabled by the interplay between electron\nhopping and spin-orbit coupling, and enhanced by the near-degeneracy of the\nconduction sub-bands. The proposed effects can provide a unique insight into\nthe electronic properties of SrTiO3 and its heterostructures.",
        "positive": "Spatial corrugation and bonding of single layer graphene on Rh(111): Topographic scanning tunneling microscopy (STM) images of epitaxial single\nlayer graphene on the Rh(111) surface reveal that extended single crystalline\ngraphene domains are produced without any defects on a large scale. High\nresolution imaging shows that the moir\\'e structure resulting from the lattice\nmismatch between the Rh(111) substrate and graphene is highly corrugated,\ncontaining regions of an additional spatial modulation in the moir\\'e supercell\ncompared with those previously reported for graphene on Ir(111) or graphene on\nRu(0001). These areas, which correspond to the \"bridge\" regions of the moir\\'e\nstructure appear as depressions in STM images indicating a strong orbital\nhybridization between the graphene layer and the metallic substrate.\nValence-band photoemission confirms the strong hybridization between graphene\nand Rh(111) which leads to the pronounced corrugation of the graphene layer.\nOur findings underline the importance of considering substrate effects in\nepitaxially grown graphene layers for the design of graphene-based nanoscale\nsystems."
    },
    {
        "anchor": "Electron-hole pairs during the adsorption dynamics of O2 on Pd(100) -\n  Exciting or not?: During the exothermic adsorption of molecules at solid surfaces dissipation\nof the released energy occurs via the excitation of electronic and phononic\ndegrees of freedom. For metallic substrates the role of the nonadiabatic\nelectronic excitation channel has been controversially discussed, as the\nabsence of a band gap could favour an easy coupling to a manifold of\nelectronhole pairs of arbitrarily low energies. We analyse this situation for\nthe highly exothermic showcase system of molecular oxygen dissociating at\nPd(100), using time-dependent perturbation theory applied to first-principles\nelectronic-structure calculations. For a range of different trajectories of\nimpinging O2 molecules we compute largely varying electron-hole pair spectra,\nwhich underlines the necessity to consider the high-dimensionality of the\nsurface dynamical process when assessing the total energy loss into this\ndissipation channel. Despite the high Pd density of states at the Fermi level,\nthe concomitant non-adiabatic energy losses nevertheless never exceed about 5%\nof the available chemisorption energy. While this supports an electronically\nadiabatic description of the predominant heat dissipation into the phononic\nsystem, we critically discuss the non-adiabatic excitations in the context of\nthe O2 spin transition during the dissociation process.",
        "positive": "Numerical Improvement of the Discrete Element Method applied to Shear of\n  Granular Media: We present a detailed analysis of the bounds on the integration step in\nDiscrete Element Method (DEM) for simulating collisions and shearing of\ngranular assemblies. We show that, in the numerical scheme, the upper limit for\nthe integration step, usually taken from the average time $t_c$ of one contact,\nis in fact not sufficiently small to guarantee numerical convergence of the\nsystem during relaxation. In particular, we study in detail how the kinetic\nenergy decays during the relaxation stage and compute the correct upper limits\nfor the integration step, which are significantly smaller than the ones\ncommonly used. In addition, we introduce an alternative approach, based on\nsimple relations to compute the frictional forces, that converges even for\nintegration steps above the upper limit."
    },
    {
        "anchor": "Optimization of the magnetic properties of FePd alloys by severe plastic\n  deformation: A FePd alloy was nanostructured by severe plastic deformation following two\ndifferent routes: ordered and disordered states were processed by high pressure\ntorsion (HPT). A grain size in a range of 50 to 150 nm is obtained in both\ncases. Severe plastic deformation induces some significant disordering of the\nlong range ordered L10 phase. However, Transmission Electron Microscopy (TEM)\ndata clearly show that few ordered nanocrystals remain in the deformed state.\nThe deformed materials were annealed to achieve nanostructured long range\nordered alloys. The transformation proceeds via a first order transition\ncharacterized by the nucleation of numerous ordered domains along grain\nboundaries. The influence of the annealing conditions (temperature and time) on\nthe coercivity was studied for both routes. It is demonstrated that starting\nwith the disorder state prior to HPT and annealing at low temperature\n(400\\degree C) leads to the highest coercivity (about 1.8 kOe).",
        "positive": "Oxide nanotemplates for self-assembling \"solid\" building blocks: It is widely accepted that self-assembling building blocks is one of the\npromising ways for engineering new materials. Recent years reveal substantial\nprogress in fabricating colloidal particles, polymer blocks and supramolecular\naggregates of organic molecules. Despite of substantial progress in molecular\nself-assembly there is still a lack of simple blocks made of \"solid matter\"\n(e.g. metals, oxides etc.) with well-defined crystal structure and spatial\norder. Here we demonstrate that ordered arrays of metal nanoclusters can be\nfabricated by self-assembly on a wide range of oxide templates. These\nnano-templates are produced either by depositing an alien oxide film or by\noxidizing a metal/metal oxide substrate."
    },
    {
        "anchor": "The influence of structural variations on the constitutive response and\n  strain variations in thin fibrous materials: The stochastic variations in the structural properties of thin fiber networks\ngovern to a great extent their mechanical performance. To assess the influence\nof local structural variability on the local strain and mechanical response of\nthe network, we propose a multiscale approach combining modeling, numerical\nsimulation and experimental measurements. Based on micro-mechanical fiber\nnetwork simulations, a continuum model describing the response at the mesoscale\nlevel is first developed. Experimentally measured spatial fields of thickness,\ndensity, fiber orientation and anisotropy are thereafter used as input to a\nmacroscale finite-element model. The latter is used to simulate the impact of\nspatial variability of each of the studied structural properties. In addition,\nthis work brings novelty by including the influence of the drying condition\nduring the production process on the fiber properties. The proposed approach is\nexperimentally validated by comparison to measured strain fields and uniaxial\nresponses. The results suggest that the spatial variability in density presents\nthe highest impact on the local strain field followed by thickness and fiber\norientation. Meanwhile, for the mechanical response, the fiber orientation\nangle with respect to the drying restraints is the key influencer and its\ncontribution to the anisotropy of the mechanical properties is greater than the\ncontribution of the fiber anisotropy developed during the fiber sheet-making.",
        "positive": "Automated determination of grain boundary energy and\n  potential-dependence using the OpenKIM framework: We present a systematic methodology, built within the Open Knowledgebase of\nInteratomic Models (OpenKIM) framework (https://openkim.org), for quantifying\nproperties of grain boundaries (GBs) for arbitrary interatomic potentials\n(IPs), GB character, and lattice structure and species. The framework currently\ngenerates results for symmetric tilt GBs in cubic materials, but can be readily\nextended to other types of boundaries. In this paper, GB energy data are\npresented that were generated automatically for Al, Ni, Cu, Fe, and Mo with 225\nIPs; the system is installed on openkim.org and will continue to generate\nresults for all new IPs uploaded to OpenKIM. The results from the atomistic\ncalculations are compared to the lattice matching model, which is a\nsemi-analytic geometric model for approximating GB energy. It is determined\nthat the energy predicted by all IPs (that are stable for the given boundary\ntype) correlate closely with the energy from the model, up to a multiplicative\nfactor. It thus is concluded that the qualitative form of the GB energy versus\ntilt angle is dominated more by geometry than the choice of IP, but that the IP\ncan strongly affect the energy level. The spread in GB energy predictions\nacross the ensemble of IPs in OpenKIM provides a measure of uncertainty for GB\nenergy predictions by classical IPs."
    },
    {
        "anchor": "Modelling of the optical properties of silver with use of six fitting\n  parameters: We propose a realistic model of the optical properties of silver, in which\ninter-band transition with a threshold energy of ~ 4 eV is described\nphenomenologically by an ensemble of oscillators with same damping constant and\na certain distribution of resonant frequencies in the interband transition\nthreshold to infinity. The contribution of the conduction electrons in the\ndielectric function is determined by the Drude formula. The proposed model\nactually contains the features of both the Drude-Lorentz model (Raki\\'c et al.\n1998) and Tauc-Lorentz model (Jian-Hong Qiu et al. 2005). However, unlike these\nworks proposed model contains only six fitting parameters, with the square root\nof the mean square deviation of the absorption coefficient and refractive index\nof silver from the experimental values in the range of 0.6 nm - 6.0 nm being of\nthe order of 0.05.",
        "positive": "Interaction of vacancies with grain boundary in aluminum: a\n  first-principles study: We present a theoretical study of the interaction of vacancies with a tilt\ngrain boundary in aluminum based on the density functional theory. The grain\nboundary volume expansion and vacancy induced contraction are calculated and\ncompared for the nearest-neighbor atoms from the defects, and the former is\nfound to be smaller than the latter. The formation energy of a vacancy placed\nat various layers in the grain boundary has been calculated and we find that\nthe grain boundary does not always act as sinks for vacancies. In fact, it\ncosts more energy to form a vacancy at the boundary plane than in the bulk,\nalthough the rest of the grain boundary region does attract vacancies. The\nmicroscopic mechanisms of grain boundary sliding and migration are investigated\nthoroughly with and without a vacancy. We find that although the vacancy can\nhinder the grain boundary motion by tripling the energy barrier of sliding and\nmigration, it can not inhibit or even delay the migration process. The vacancy\nplaced at the first layer from the interface is found to be trapped at the\nlayer and not able to follow the migrating interface."
    },
    {
        "anchor": "Role of anisotropic strength and stiffness in governing the initiation\n  and propagation of yielding in polycrystalline solids: The ratio of directional strength-to-stiffness is important in governing the\nrelative order in which individual crystals within a polycrystalline aggregate\nwill yield as the aggregate is loaded. In this paper, a strength-to-stiffness\nparameter is formulated for multiaxial loading that extends the development of\nWong and Dawson for uniaxial loading. Building on the principle of\nstrength-to-stiffness, a methodology for predicting the macroscopic stresses at\nwhich elements in a finite element mesh yield is developed. This analysis uses\nelastic strain data from one increment of a purely elastic finite element\nsimulation to make the prediction, given knowledge of the single-crystal yield\nsurface. Simulations of austenitic strainless steel AL6XN are used to\ndemonstrated the effectivness of the strength-to-stiffness parameter and yield\nprediction methodology.",
        "positive": "Study of Thermal Properties of Graphene-Based Structures Using the Force\n  Constant Method: The thermal properties of graphene-based materials are theoretically\ninvestigated. The fourth-nearest neighbor force constant method for phonon\nproperties is used in conjunction with both the Landauer ballistic and the\nnon-equilibrium Green's function techniques for transport. Ballistic phonon\ntransport is investigated for different structures including graphene, graphene\nantidot lattices, and graphene nanoribbons. We demonstrate that this particular\nmethodology is suitable for robust and efficient investigation of phonon\ntransport in graphene-based devices. This methodology is especially useful for\ninvestigations of thermoelectric and heat transport applications."
    },
    {
        "anchor": "Growth mechanism of nanocrystals in solution: ZnO, a case study: We investigate the mechanism of growth of nanocrystals from solution using\nthe case of ZnO. Spanning a wide range of values of the parameters, such as the\ntemperature and the reactant concentration, that control the growth, our\nresults establish a qualitative departure from the widely accepted diffusion\ncontrolled coarsening (Ostwald ripening) process quantified in terms of the\nLifshitz-Slyozov-Wagner theory. Further, we show that these experimental\nobservations can be qualitatively and quantitatively understood within a growth\nmechanism that is intermediate between the two well-defined limits of diffusion\ncontrol and kinetic control.",
        "positive": "Periodized discrete elasticity models for defects in graphene: The cores of edge dislocations, edge dislocation dipoles and edge dislocation\nloops in planar graphene have been studied by means of periodized discrete\nelasticity models. To build these models, we have found a way to discretize\nlinear elasticity on a planar hexagonal lattice using combinations of\ndifference operators that do not involve symmetrically all the neighbors of an\natom. At zero temperature, dynamically stable cores of edge dislocations may be\nheptagon-pentagon pairs (glide dislocations) or octagons (shuffle dislocations)\ndepending on the choice of initial configuration. Possible cores of edge\ndislocation dipoles are vacancies, pentagon-octagon-pentagon divacancies,\nStone-Wales defects and 7-5-5-7 defects. While symmetric vacancies, divacancies\nand 7-5-5-7 defects are dynamically stable, asymmetric vacancies and 5-7-7-5\nStone-Wales defects seem to be unstable."
    },
    {
        "anchor": "The selective transfer of patterned graphene: Graphene is an emerging class of two-dimensional (2D) material with unique\nelectrical properties and a wide range of potential practical applications. In\naddition, graphene hybrid structures combined with other 2D materials, metal\nmicrostructures, silicon photonic crystal cavities, and waveguides have more\nextensive applications in van der Waals heterostructures, hybrid graphene\nplasmonics, hybrid optoelectronic devices, and optical modulators. Based on\nwell-developed transfer methods, graphene grown by chemical vapor deposition\n(CVD) is currently used in most of the graphene hybrid applications. Although\nmechanical exfoliation of highly oriented pyrolytic graphite provides the\nhighest-quality graphene, the transfer of the desired microcleaving graphene\n(MG) to the structure at a specific position is a critical challenge, that\nlimits the combination of MG with other structures. Herein, we report a new\ntechnique for the selective transfer of MG patterns and devices onto chosen\ntargets using a bilayer-polymer structure and femtosecond laser\nmicrofabrication. This selective transfer technique, which exactly transfers\nthe patterned graphene onto a chosen target, leaving the other flakes on the\noriginal substrate, provides an efficient route for the fabrication of MG-based\nmicrodevices. This method will facilitate the preparation of van der Waals\nheterostructures and enable the optimization of the performance of graphene\nhybrid devices.",
        "positive": "Ranking the Synthesizability of Hypothetical Zeolites with the Sorting\n  Hat: Zeolites are nanoporous alumino-silicate frameworks widely used as catalysts\nand adsorbents. Even though millions of distinct siliceous networks can be\ngenerated by computer-aided searches, no new hypothetical framework has yet\nbeen synthesized. The needle-in-a-haystack problem of finding promising\ncandidates among large databases of predicted structures has intrigued\nmaterials scientists for decades; most work to date on the zeolite problem has\nbeen limited to intuitive structural descriptors. Here, we tackle this problem\nthrough a rigorous data science scheme-the \"zeolite sorting hat\"-that exploits\ninteratomic correlations to produce a 95% real versus theoretical zeolites\nclassification accuracy. The hypothetical frameworks that are grouped together\nwith known zeolites are promising candidates for synthesis, that can be further\nranked by estimating their thermodynamic stability. A critical analysis of the\nclassifier reveals the decisive structural features. Further partitioning into\ncompositional classes provides guidance in the design of synthetic strategies."
    },
    {
        "anchor": "Magnetism in Exact Exchange Density Functional Theory: The magnetic properties of the intermetallic compound FeAl are investigated\nusing exact exchange density functional theory. This is implemented within a\nstate of the art all-electron full potential method. We find that FeAl is\nmagnetic with a moment of 0.70 $\\mu_B$, close to the LSDA result of 0.69\n$\\mu_B$. A comparison with the non-magnetic density of states with experimental\nnegative binding energy result shows a much better agreement than any previous\ncalculations. We attribute this to the fine details of the exchange field, in\nparticular its asymmetry, which is captured very well with the orbital\ndependent exchange potential.",
        "positive": "Low-Scaling Algorithm for the Random Phase Approximation using Tensor\n  Hypercontraction with k-point Sampling: We present a low-scaling algorithm for the random phase approximation (RPA)\nwith \\textbf{k}-point sampling in the framework of tensor hypercontraction\n(THC) for electron repulsion integrals (ERIs). The THC factorization is\nobtained via a revised interpolative separable density fitting (ISDF) procedure\nwith a momentum-dependent auxiliary basis for generic single-particle Bloch\norbitals. Our formulation does not require pre-optimized interpolating points\nnor auxiliary bases, and the accuracy is systematically controlled by the\nnumber of interpolating points. The resulting RPA algorithm scales linearly\nwith the number of \\textbf{k}-points and cubically with the system size without\nany assumption on sparsity or locality of orbitals. The errors of ERIs and RPA\nenergy show rapid convergence with respect to the size of the THC auxiliary\nbasis, suggesting a promising and robust direction to construct efficient\nalgorithms of higher-order many-body perturbation theories for large-scale\nsystems."
    },
    {
        "anchor": "Valence fluctuations in Sn(Pb)$_2$P$_2$S$_6$ ferroelectrics: The valence fluctuations which are related to the charge disproportionation\nof phosphorous ions $P^{4+} + P^{4+}\\rightarrow P^{3+} + P^{5+}$ are the origin\nof ferroelectric and quantum paraelectric states in Sn(Pb)$_2$P$_2$S$_6$\nsemiconductors. They involve recharging of SnPS$_3$ or PbPS$_3$ structural\ngroups which could be represented as half-filled sites in the crystal lattice.\nTemperature-pressure phase diagram for Sn$_2$P$_2$S$_6$ compound and\ntemperature-composition phase diagram for (Pb$_y$Sn$_{1-y}$)$_2$P$_2$S$_6$\nmixed crystals, which include tricritical points and where a temperature of\nphase transitions decrease to 0 K, together with the data about some softening\nof low energy optic phonons and rise of dielectric susceptibility at cooling in\nquantum paraelectric state of Pb$_2$P$_2$S$_6$, are analyzed by GGA electron\nand phonon calculations and compared with electronic correlations models. The\nanharmonic quantum oscillators model is developed for description of phase\ndiagrams and temperature dependence of dielectric susceptibility.",
        "positive": "Studying of the interlayer interaction in magnetic multilayers (FM/I/FM)\n  measuring the FMR peak asymmetry: We experimentally study the interlayer interaction in a magnetic multilayer\nsystem ferromagnet/insulator/ferromagnet with different spacer thickness. We\ndemonstrate that the sign and the magnitude of the interaction can be deduced\nfrom the FMR peak shape rather than from the FMR peak shift. The proposed\ntechnique allows studying the interlayer interaction using a single sample\n(without a reference sample for comparison)."
    },
    {
        "anchor": "Determining phase transition using potential energy distribution and\n  surface energy of Pd nanoparticles: Molecular dynamics simulation is employed to understand the thermodynamic\nbehavior of cuboctahedron (cub) and icosahedron (ico) nanoparticles with 2-20\nnumber of shells (55-28741 atoms). The embedded atom method was used to\ndescribe the interatomic potential. Conventional melting criteria such as\npotential energy and specific heat capacity (C_p) caloric curves as well as\nstructure analysis by radial distribution function (G(r)) and common neighbor\nanalysis (CNA) were utilized simultaneously to provide a comprehensive picture\nof the melting process. It is shown that the potential energy distribution and\nsurface energy (gamma_p) proposed here are holding several advantages over\nprevious criteria. In particular, potential energy distribution can distinguish\nbetween interior and surface atoms and even corner, edge and plane atoms at the\nsurface. While G(r) and CNA are not surface sensitive methods and cannot\ndistinguish between surface melting and an allotropic transition. It is also\nshown that allotropic change appears more clearly in C_p and gamma_p rather\nthan potential energy. However, determining accurate C_p requires enough\nsampling to be averaged. Finally, a few issues in the current methods for\ndetermining gamma_p were discussed and a simple method based on available\nmodels was proposed which, independent of estimation of the surface area,\npredicts the correct temperature and size-dependent trend in agreement with\nGuggenheim-Katayama and Tolman's models, respectively.",
        "positive": "Achieving ferroelectricity in a centrosymmetric high-performance\n  semiconductor by strain engineering: Phase engineering by strains in 2D semiconductors is of great importance for\na variety of applications. Here, we present a study of strain induced\nferroelectric (FE) transition on bismuth oxyselenide (Bi$_2$O$_2$Se) films, a\nhigh-performance (HP) semiconductor for next-generation electronics.\nBi$_2$O$_2$Se is non-FE at ambient. Upon a loading force $\\gtrsim 400$ nN,\npiezoelectric force responses exhibit butterfly loops on magnitude and\n180$^\\textrm{o}$ phase switching. By carefully ruling out extrinsic factors,\nthese features are attributed to a transition to FE phase. The transition is\nfurther proved by the appearance of a sharp peak on optical second harmonic\ngeneration under an uniaxial strain. Fundamentally, solids with paraelectric at\nambient and FE under strains are scarce. FE transition is discussed with the\nhelp of first-principle calculations and theoretical simulations. The switching\nof FE polarization acts as a knob for Schottky barrier engineering at contacts\nand serves as basis for a memristor with a huge switching ratio of 10$^6$. Our\nwork endows a new degree of freedom to a HP electronic/optoelectronic\nsemiconductor and the integration of FE and HP semiconductivity paving the way\nfor multiple exciting functionalities, including HP neuromorphic computation\nand bulk piezophotovoltaic."
    },
    {
        "anchor": "Local lattice distortions around $\\rm{Mn^{2+}}$ cause in-plane uniaxial\n  magnetic anisotropy in Ga(Mn)As: We theoretically investigate the interplay between local lattice distortions\naround $\\rm{Mn^{2+}}$ ion impurity and the ion's magnetic polarization,\nmediated through spin-orbit coupling of hole. We show that the tetrahedral\nsymmetry around $\\rm{Mn^{2+}}$ ion impurity is spontaneously broken even in the\nparamagnetic regime. Modest local lattice distortions around the impurity\n$\\rm{Mn^{2+}}$ ion, along with the growth strain, stabilize magnetization along\n$< 110 >$ directions, in the ferromagnetic regime. We explain the\nexperimentally observed in-plane uniaxial magnetic anisotropy seen in this\nsystem using this symmetry-breaking mechanism.",
        "positive": "On the use of Water and Methanol with Zeolites for Heat Transfer: Reducing carbon dioxide emissions has become a must in society, being crucial\nto find alternatives to supply the energy demand. Adsorption-based cooling and\nheating technologies are receiving attention for thermal energy storage\napplications. In this paper, we study the adsorption of polar working fluids in\nhydrophobic and hydrophilic zeolites by means of experimental\nquasi-equilibrated temperature-programmed desorption and adsorption combined\nwith Monte Carlo simulations. We measured and computed water and methanol\nadsorption isobars in high-silica HS-FAU, NaY, and NaX zeolites. We use the\nexperimental adsorption isobars to develop a set of parameters to model the\ninteraction between methanol and the zeolite and cations. Once having the\nadsorption of these polar molecules, we use a mathematical model based on the\npotential theory of adsorption of Dubinin-Polanyi to assess the performance of\nthe adsorbate-working fluids for heat storage applications. We found that the\nuse of molecular simulation is an alternative for investigating energy storage\napplications since we can reproduce, complement, and extend experimental\nobservations. Our results highlight the importance of controlling the\nhydrophilic/hydrophobic nature of the zeolites by changing the Al content to\nmaximize the working conditions of the heat storage device."
    },
    {
        "anchor": "Effect of Net Charge on the Relative Stability of 2D Boron Allotropes: We study the effect of electron doping on the bonding character and stability\nof two-dimensional (2D) structures of elemental boron, called borophene, which\nis known to form many stable allotropes. Our {\\em ab initio} calculations for\nthe neutral system reveal previously unknown stable 2D $\\epsilon$-B and\n$\\omega$-B structures. We find that the chemical bonding characteristic in this\nand other boron structures is strongly affected by extra charge. Beyond a\ncritical degree of electron doping, the most stable allotrope changes from\n$\\epsilon$-B to a buckled honeycomb structure. Additional electron doping,\nmimicking a transformation of boron to carbon, causes a gradual decrease in the\ndegree of buckling of the honeycomb lattice that can be interpreted as\npiezoelectric response. Net electron doping can be achieved by placing\nborophene in direct contact with layered electrides such as Ca$_{2}$N. We find\nthat electron doping can be doubled by changing from the B/Ca$_{2}$N bilayer to\nthe Ca$_{2}$N/B/Ca$_{2}$N sandwich geometry.",
        "positive": "Strain tunability of perpendicular magnetic anisotropy in van der Waals\n  ferromagnets VI3: Layered ferromagnets with high coercivity have special applications in\nnanoscale memory elements in electronic circuits, such as data storage.\nTherefore, searching for new hard ferromagnets and effectively tuning or\nenhancing the coercivity are the hottest topics in layered magnets today. Here,\nwe report a strain tunability of perpendicular magnetic anisotropy in van der\nWaals (vdW) ferromagnets VI3 using magnetic circular dichroism measurements.\nFor an unstrained flake, the M-H curve shows a rectangular-shaped hysteresis\nloop with perpendicular magnetic anisotropy and a large coercivity (up to 1.775\nT at 10 K). Furthermore, the coercivity can be enhanced to a maximum of 2.6 T\nat 10 K under a 2.9% in-plane tensile strain. Our DFT calculations show that\nthe magnetic anisotropy energy (MAE) can be dramatically increased after\napplying an in-plain tensile strain, which contributes to the enhancement of\ncoercivity in the VI3 flake. Meanwhile, the strain tunability on the coercivity\nof CrI3, with a similar crystal structure, is limited. The main reason is the\nstrong spin-orbital coupling in V3+ in VI6 octahedra in comparison with that in\nCr3+. The strain tunability of coercivity in VI3 flakes highlights its\npotential for integration into vdW heterostructures, paving the way toward\nnanoscale spintronic devices and applications in the future."
    },
    {
        "anchor": "Toward a virtual material for lifetime prediction of CMCs: A first version of a multi-scale, multi-physic hybrid model --called virtual\nmaterial-- for predictions on Self-Healing Ceramic Matrix Composite's (CMCs)\nlifetime is presented. The model has a mechanical and a chemical part, which\nare presented here in their actual state of development. The mechanical part\nprovides precise data for the chemical models through an hybrid --melting\ncontinuum damage macro model discrete crack surfaces-- representation of the\nmorphology of the crack network at yarn scale. The chemical part should provide\npredictions on the structure's lifetime using a model of the self-healing\nprocess, not yet achieved then not presented here, and a model of fiber\nsub-critical failure under mechanical and chemical load.",
        "positive": "Heat conduction in multifunctional nanotrusses studied using Boltzmann\n  transport equation: Materials that possess low density, low thermal conductivity, and high\nstiffness are desirable for engineering applications, but most materials cannot\nrealize these properties simultaneously due to the coupling between them.\nNanotrusses, which consist of hollow nanoscale beams architected into a\nperiodic truss structure, can potentially break these couplings due to their\nlattice architecture and nanoscale features. In this work, we study heat\nconduction in the exact nanotruss geometry by solving the frequency-dependent\nBoltzmann transport equation using a variance-reduced Monte Carlo algorithm. We\nshow that their thermal conductivity can be described with only two parameters,\nsolid fraction and wall thickness. Our simulations predict that nanotrusses can\nrealize unique combinations of mechanical and thermal properties that are\nchallenging to achieve in typical materials."
    },
    {
        "anchor": "Defect engineering of the electronic transport through cuprous oxide\n  interlayers: The electronic transport through Au-(Cu$_{2}$O)$_n$-Au junctions is\ninvestigated using first-principles calculations and the nonequilibrium Green's\nfunction method. The effect of varying the thickness (i.e., $n$) is studied as\nwell as that of point defects and anion substitution. For all Cu$_{2}$O\nthicknesses the conductance is more enhanced by bulk-like (in contrast to\nnear-interface) defects, with the exception of O vacancies and Cl\nsubstitutional defects. A similar transmission behavior results from Cu\ndeficiency and N substitution, as well as from Cl substitution and N\ninterstitials for thick Cu$_{2}$O junctions. In agreement with recent\nexperimental observations, it is found that N and Cl doping enhances the\nconductance. A Frenkel defect, i.e., a superposition of an O interstitial and O\nsubstitutional defect, leads to a remarkably high conductance. From the\nanalysis of the defect formation energies, Cu vacancies are found to be\nparticularly stable, in agreement with earlier experimental and theoretical\nwork.",
        "positive": "Room temperature Epitaxial Stabilization of a Tetragonal Phase in ARuO3\n  (A=Ca,Sr) Thin Films: We demonstrate that SrRuO3 and CaRuO3 thin films undergo a room temperature\nstructural phase transition driven by the substrate imposed epitaxial biaxial\nstrain. As tensile strain increases, ARuO3 (A=Ca, Sr) films transform from the\northorhombic phase which is usually observed in bulk SrRuO3 and CaRuO3 at room\ntemperature, into a tetragonal phase which in bulk samples is only stable at\nhigher temperatures. More importantly, we show that the observed phenomenon\nstrongly affects the electronic and magnetic properties of ARuO3 thin films\nthat are grown on different single crystal substrates which in turn offers the\npossibility to tune these properties."
    },
    {
        "anchor": "An all-electrical torque differential magnetometer operating under\n  ambient conditions: An all-electrical torque differential magnetometry (also known as cantilever\nmagnetometry) setup employing piezoelectric quartz tuning forks is\ndemonstrated. The magnetometer can be operated under ambient conditions as well\nas low temperatures and pressures. It extends the allowed specimen mass range\nup to several 10 $\\mu$g without any significant reduction in the sensitivity.\nOperation under ambient conditions and a simple all-electrical design of the\nmagnetometer should allow for an easy integration with other experimental\nsetups. The uniaxial magnetic anisotropy of a 25 $\\mu$m diameter iron wire,\nmeasured under ambient conditions with a high signal to noise ratio, was found\nto be in good agreement with its literature value. Further applications of the\ntechnique are discussed.",
        "positive": "Tunneling in graphene-topological insulator hybrid devices: Hybrid graphene-topological insulator (TI) devices were fabricated using a\nmechanical transfer method and studied via electronic transport. Devices\nconsisting of bilayer graphene (BLG) under the TI Bi$_2$Se$_3$ exhibit\ndifferential conductance characteristics which appear to be dominated by\ntunneling, roughly reproducing the Bi$_2$Se$_3$ density of states. Similar\nresults were obtained for BLG on top of Bi$_2$Se$_3$, with 10-fold greater\nconductance consistent with a larger contact area due to better surface\nconformity. The devices further show evidence of inelastic phonon-assisted\ntunneling processes involving both Bi$_2$Se$_3$ and graphene phonons. These\nprocesses favor phonons which compensate for momentum mismatch between the TI\n$\\Gamma$ and graphene $K, K'$ points. Finally, the utility of these tunnel\njunctions is demonstrated on a density-tunable BLG device, where the\ncharge-neutrality point is traced along the energy-density trajectory. This\ntrajectory is used as a measure of the ground-state density of states."
    },
    {
        "anchor": "Thermodynamic stability of Li-B-C compounds from first principles: Prediction of high-$T_{\\rm{c}}$ superconductivity in hole-doped Li$_x$BC two\ndecades ago has brought about an extensive effort to synthesize new materials\nwith honeycomb B-C layers, but the thermodynamic stability of Li-B-C compounds\nremains largely unexplored. In this study, we use density functional theory to\ncharacterize well-established and recently reported Li-B-C phases. Our\ncalculation of the Li chemical potential in Li$_x$BC helps estimate the\n($T$,$P$) conditions required for delithiation of the LiBC parent material,\nwhile examination of B-C phases helps rationalize the observation of metastable\nBC$_3$ polymorphs with honeycomb and diamond-like morphologies. At the same\ntime, we demonstrate that recently reported BC$_3$, LiBC$_3$, and Li$_2$B$_2$C\nphases with new crystal structures are both dynamically and thermodynamically\nunstable. With a combination of evolutionary optimization and rational design,\nwe identify considerably more natural and favorable Li$_2$B$_2$C configurations\nthat, nevertheless, remain above the thermodynamic stability threshold.",
        "positive": "Magnetic and Orbital Order in LaMnO$_3$ under Uniaxial Strain: A Model\n  Study: The effect of uniaxial strain on electronic structure and magnetism in\nLaMnO$_3$ is studied from a model Hamiltonian that illustrates the competition\nbetween the Jahn-Teller, super exchange, and double exchange interactions. We\nretain in our model the three main octahedral distortions ($Q_1, Q_2$, and\n$Q_3$), which couple to the Mn $(e_g)$ electrons. Our results show the ground\nstate to be a type A antiferromagnetic (AFM) insulating state for the\nunstrained case, consistent with experiments. With tensile strain (stretching\nalong the c axis), the ground state changes into a ferromagnetic and eventually\ninto a type G$^\\prime$ AFM structure, while with compressive strain, we find\nthe type A switching into a type G structure. The orbital ordering, which\ndisplays the well known checkerboard $x^2-1 / y^2-1$ structure for the\nunstrained case, retains more or less the same character for compressive\nstrain, while changing into the $z^2-1$ character for tensile strains. While\n$Q_1$ and $Q_3$ are fixed by the strain components $\\varepsilon_{xx}$ and\n$\\varepsilon_{zz}$ in our model, the magnitude of the in-plane distortion mode\n(Q$_2$), which varies to minimize the total energy, slowly diminishes with\ntensile strain, completely disappearing as the FM state is entered. Within our\nmodel, the FM state is metallic, while the three AFM states are insulating."
    },
    {
        "anchor": "Bare and Polymer Coated Iron Oxide Superparamagnetic Nanoparticles for\n  Effective Removal of U (VI) from Acidic and Neutral Aqueous Medium: Superparamagnetic {\\gamma}-Fe2O3 nanoparticles (5 nm diameter) were\nsynthesized in water. The bare particles exhibit good colloidal stability at ~\npH 2 because of the strong electrostatic repulsion with a surface charge of +25\nmV. The polyacrylic acid (PAA)-coated particles exhibit remarkable colloidal\nstability at ~ pH 7 with abundant free carboxyl groups as reactive sites for\nsubsequent functionalization. In this work, we used zeta potential analysis,\ntransmission electron microscopy, small angle X-ray scattering, and Inductively\ncoupled plasma mass spectrometry to investigate the adsorption behavior of U\n(VI) on bare and coated colloidal superparamagnetic nanoparticles at pH 2 and\npH 7. At pH 2, uranyl ion (UO22+) absorbed on the surface of the bare particles\nwith decreasing particle surface charge. This induced particle agglomeration.\nAt pH 7, uranyl ion (UO22+) hydrolyzed and formed plate-like particles of\nuranium hydroxide that were ~ 50 nm in diameter. The PAA-coated iron oxide\nnanoparticles absorbed on the surface of these U (VI) hydroxide plates to form\nlarge aggregates that precipitate to the bottom of the dispersion. At both pH 2\nand pH 7, the resulting U (VI)/nanoparticle complex can be easily collected and\nextracted from the aqueous environment via an external magnetic field. The\nresults show that both bare and polymer-coated superparamagnetic {\\gamma}-Fe2O3\nnanoparticles are potential absorbents for removing U (VI) from water.",
        "positive": "Deep-learning-based prediction of nanoparticle phase transitions during\n  in situ transmission electron microscopy: We develop the machine learning capability to predict a time sequence of\nin-situ transmission electron microscopy (TEM) video frames based on the\ncombined long-short-term-memory (LSTM) algorithm and the features\nde-entanglement method. We train deep learning models to predict a sequence of\nfuture video frames based on the input of a sequence of previous frames. This\nunique capability provides insight into size dependent structural changes in Au\nnanoparticles under dynamic reaction condition using in-situ environmental TEM\ndata, informing models of morphological evolution and catalytic properties. The\nmodel performance and achieved accuracy of predictions are desirable based on,\nfor scientific data characteristic, based on limited size of training data\nsets. The model convergence and values for the loss function mean square error\nshow dependence on the training strategy, and structural similarity measure\nbetween predicted structure images and ground truth reaches the value of about\n0.7. This computed structural similarity is smaller than values obtained when\nthe deep learning architecture is trained using much larger benchmark data\nsets, it is sufficient to show the structural transition of Au nanoparticles.\nWhile performance parameters of our model applied to scientific data fall short\nof those achieved for the non-scientific big data sets, we demonstrate model\nability to predict the evolution, even including the particle structural phase\ntransformation, of Au nano particles as catalyst for CO oxidation under the\nchemical reaction conditions. Using this approach, it may be possible to\nanticipate the next steps of a chemical reaction for emerging automated\nexperimentation platforms."
    },
    {
        "anchor": "Quantum defects in 2D transition metal dichalcogenides for\n  THz-technologies: Terahertz technologies are important for a number of emerging applications,\nsuch as for next generation communications. We predict that transition metal\nsubstitutional defects in two-dimensional transition metal dichalcogenides\n(TMDs) can serve as quantum defects for terahertz technologies. Central to this\nprediction is the finding that the zero field splittings between spin sublevels\nin such defects are typically in the sub-terahertz to terahertz range due to\nthe large spin-orbit coupling in these systems. As a proof of concept, we\nconsider different transition metal impurities from across the periodic table,\nin prototypical TMDs, MoS2 and WSe2. Using first principles calculations, we\ndemonstrate that selected spin triplet defects can potentially serve as qubits\noperating in the terahertz regime. We also propose defects that can potentially\nbe quantum sources of terahertz radiation. Our research broadens the scope of\nadvancements in quantum information science and lays a foundation for their\nintegration with THz technologies.",
        "positive": "Many body effects in the excitation spectrum of a defect in SiC: We show that electron correlations control the photophysics of defects in SiC\nthrough both renormalization of the quasiparticle bandstructure and exciton\neffects. We consider the carbon vacancy, which is a well-identified defect with\ntwo possible excitation channels that involve conduction and valence band\nstates. Corrections to the Kohn-Sham ionization levels are found to strongly\ndepend on the occupation of the defect state. Excitonic effects introduce a red\nshift of 0.23 eV. The analysis unambigiously re-assigns excitation mechanism at\nthe thresholds in photo-induced paramagnetic resonance measurements [J.\nDashdorj \\emph{et al.}, J. Appl. Phys. \\textbf{104}, 113707 (2008)]."
    },
    {
        "anchor": "Relaxation of creep strain in paper: In disordered, viscoelastic or viscoplastic materials a sample response\nexhibits a recovery phenomenon after the removal of a constant load or after\ncreep. We study experimentally the recovery in paper, a quasi two-dimensional\nsystem with intrinsic structural disorder. The deformation is measured by using\nthe digital image correlation (DIC) method. By the DIC we obtain accurate\ndisplacement data and the spatial fields of deformation and recovered strains.\nThe averaged results are first compared to several heuristic models for in\nparticular viscoelastic polymer materials. The most important experimental\nquantity is the permanent creep strain, and we analyze whether it is non-zero\nby fitting the empirical models of viscoelasticity. We then present in more\ndetail the spatial recovery behavior results from DIC, and show that they\nindicate a power-law -type relaxation. We outline results on sample-to-sample\nvariation and collective, spatial fluctuations in the recovery behaviour. An\ninterpretation is provided of the relaxation in the general context of glassy,\ninteracting systems with barriers.",
        "positive": "All-nitride and In-free Al$_x$Ga$_{1-x}$N:Mn/GaN distributed Bragg\n  reflectors for the near-infrared: Since the technological breakthrough prompted by the inception of light\nemitting diodes based on III-nitrides, these material systems have emerged as\nstrategic semiconductors not only for the lighting of the future, but also for\nthe new generation of high-power electronic and spintronic devices. While\nIII-nitride optoelectronics in the visible and ultraviolet spectral range is\nwidely established, all-nitride and In-free efficient devices in the\nnear-infrared (NIR) are still wanted. Here, through a comprehensive protocol of\ndesign, modeling, epitaxial growth and in-depth characterization, we develop\nAl$_x$Ga$_{1-x}$N:Mn/GaN NIR distributed Bragg reflectors and we show their\nefficiency in combination with GaN:(Mn,Mg) layers containing Mn-Mg$_{k}$\ncomplexes optically active in the telecommunication range of wavelengths."
    },
    {
        "anchor": "Magnetic oscillations in silicene: In this work the magnetic oscillations (MO) in pristine silicene at $T=0$ K\nare studied. Considering a constant electron density we obtain analytical\nexpressions for the ground state internal energy and magnetization, under a\nperpendicular electric and magnetic field, taking in consideration the Zeeman\neffect. It is found that the MO are sawtooth-like, depending on the change in\nthe last occupied energy level. This leads us to a classification of the MO\npeaks in terms of the Landau level (LL), valley or spin changes. Using this\nclassification we analyze the MO for different values of the electric field\n$E_{z}$. When $E_{z}=0$, the energy levels have a valley degeneracy and the MO\npeaks occur only whenever the last energy level changes its LL and/or spin.\nWhen $E_{z}\\neq0$, the valley degeneracy is broken and new MO peaks appear,\nassociated with the valley change in the last energy level. By analyzing the MO\npeaks amplitude it is possible to extract information about the Fermi velocity\nand the spin-orbit interaction strength. Finally we analyze the MO frequencies,\nwhich can also be associated with the change of LL, valley or spin in the last\nenergy level.",
        "positive": "Tunable discontinuous shear thickening in capillary flow of MR\n  suspensions: Very concentrated suspensions of iron particles in water or ethylene glycol\ncan be obtained thanks to the use of superplasticizer molecules used in cement\nindustry. At high volume fractions, these suspensions show a discontinuous\nshear thickening which was thoroughly characterized in rotational geometries.\nWe will show that the jamming transition is also present in a capillary flow,\nand that it manifests through the formation of a non-consolidated porous medium\nat the constriction between the barrel and the capillary. In suspension of iron\nparticles, the dynamics of formation of this porous medium, and so the\npressure, can be controlled by a low magnetic field and is reversible for a\nconstant volume flow rate, opening potential new applications in the domain of\ndampers and force control devices."
    },
    {
        "anchor": "Orthogonal and Non-Orthogonal Tight Binding parameters for III-V\n  Semiconductors Nitrides: A simulated annealing (SA) approach is employed in the determination of\ndifferent tight binding (TB) sets of parameters for the nitride semiconductors\nAlN, GaN and InN, as well their limitations and potentialities are also\ndiscussed. Two kinds of atomic basis set are considered: (\\textit{i}) the\northogonal $sp^3s*$ with interaction up to second neighbors and (\\textit{ii}) a\n$spd$ non-orthogonal set, with the Hamiltonian matrix elements calculated\nwithin the Extended H\\\"uckel Theory (EHT) prescriptions. For the non-orthogonal\nmethod, TB parameters are given for both zincblend and wurtzite crystalline\nstructures.",
        "positive": "Studies of Multiferroic System of LiCu2O2 II Magnetic Structures of Two\n  Ordered Phases with Incommensurate Modulations: Neutron diffraction and 7Li-NMR have been applied to determine the\nmultiferroic system LiCu2O2, which has four chains (ribbon chains) of\nedge-sharing CuO4 square planes in a unit cell. We have confirmed that there\nare successive magnetic transitions at TN1=24.5 K and TN2=22.8 K. In the T\nregion between TN1 and TN2, the quasi one-dimensional spins (S=1/2) of Cu2+\nions within a chain have a collinear and sinusoidally modulated structure with\nCu-moments parallel to the c-axis and with the modulation vector along the\nb-axis. At T < TN2, an ellipsoidal helical spin structure with the\nincommensurate modulation has been found. Here, we present detailed parameters,\ndescribing the modulation amplitudes, helical axis vectors as well as the\nrelative phases of the modulations of four ribbon chains, which can well\nreproduce both the NMR and neutron results in the two magnetically ordered\nphases. This finding of the rather precise magnetic structures enables us to\ndiscuss the relationship between the magnetic structure and the multiferroic\nnature of the present system in zero magnetic field, as presented in our\ncompanion paper (paper I), and open a way how to understand the reported\nelectric polarization under the finite magnetic field."
    },
    {
        "anchor": "Atomic-Scale Visualization of Chiral Charge Density Wave States and\n  Their Reversible Transition: Chirality is essential for various amazing phenomena in life and matter.\nHowever,chirality and its switching in electronic superlattices, such as charge\ndensity wave(CDW) arrays, remain elusive. In this study, we characterize the\nchirality transition with atom-resolution imaging in a single-layer NbSe2 CDW\npattern by technique of scanning tunneling microscopy. The atomic lattice of\nthe CDW array is found continuous and intact although its chirality is\nswitched. Several intermediate states are tracked by time-resolved imaging,\nrevealing the fast and dynamic chirality transition. Importantly, the switching\nis reversibly realized with an external electric-field. Our findings unveil the\ndelicate transition process of chiral CDW array in a 2D crystal down to the\natomic scale and may be applicable for future nanoscale devices.",
        "positive": "Surface morphological evolutions on single crystal films by strong\n  anisotropic drift-diffusion under the capillary and electromigration forces: The morphological evolution of voids at the unpassivated surfaces and the\nsidewalls of the single crystal metallic films are investigated via computer\nsimulations by using the novel mathematical model developed by Ogurtani relying\non the fundamental postulates of irreversible thermodynamics. The effects of\nthe drift-diffusion anisotropy on the development of the surface morphological\nscenarios are fully explored under the action of the electromigration (EM) and\ncapillary forces (CF), utilizing numerous combination of the surface textures\nand the directions of the applied electric field. The interconnect failure time\ndue to the EM induced wedge shape internal voids and the incubation time of the\noscillatory surface waves, under the severe instability regimes, are deduced by\nthe novel renormalization procedures applied on the outputs of the computer\nsimulation experiments."
    },
    {
        "anchor": "Neutron Scattering Study of the Localized Mode in the beta-Pyrochlore\n  Superconductors AOs2O6: Inelastic neutron scattering and neutron powder diffraction experiments were\ncarried out to investigate a localized mode, proposed from various bulk\nmeasurements, in the beta-pyrochlore AOs2O6 (A=K, Rb, Cs). The localized mode\nwas identified in all the three compounds as well as another beta-pyrochlore\nCsW2O6. The anharmonicity of the mode is weak in RbOs2O6 and CsOs2O6 but\nsubstantial in KOs2O6.",
        "positive": "Non-Adiabatic Potential-Energy Surfaces by Constrained\n  Density-Functional Theory: Non-adiabatic effects play an important role in many chemical processes. In\norder to study the underlying non-adiabatic potential-energy surfaces (PESs),\nwe present a locally-constrained density-functional theory approach, which\nenables us to confine electrons to sub-spaces of the Hilbert space, e.g. to\nselected atoms or groups of atoms. This allows to calculate non-adiabatic PESs\nfor defined charge and spin states of the chosen subsystems. The capability of\nthe method is demonstrated by calculating non-adiabatic PESs for the scattering\nof a sodium and a chlorine atom, for the interaction of a chlorine molecule\nwith a small metal cluster, and for the dissociation of an oxygen molecule at\nthe Al(111) surface."
    },
    {
        "anchor": "Hidden domain boundary dynamics towards crystalline perfection: A central paradigm of non-equilibrium physics concerns the dynamics of\nheterogeneity and disorder, impacting processes ranging from the behavior of\nglasses to the emergent functionality of active matter. Understanding these\ncomplex mesoscopic systems requires probing the microscopic trajectories\nassociated with irreversible processes, the role of fluctuations and entropy\ngrowth, and the timescales on which non-equilibrium responses are ultimately\nmaintained. Approaches that illuminate these processes in model systems may\nenable a more general understanding of other heterogeneous non-equilibrium\nphenomena, and potentially define ultimate speed and energy cost limits for\ninformation processing technologies. Here, we apply ultrafast single shot x-ray\nphoton correlation spectroscopy to resolve the non-equilibrium, heterogeneous,\nand irreversible mesoscale dynamics during a light-induced phase transition.\nThis approach defines a new way of capturing the nucleation of the induced\nphase, the formation of transient mesoscale defects at the boundaries of the\nnuclei, and the eventual annihilation of these defects, even in systems with\ncomplex polarization topologies. A non-equilibrium response spanning >10 orders\nof magnitude in timescales is observed, with multistep behavior similar to the\nplateaus observed in supercooled liquids and glasses. We show how the observed\ntime-dependent long-time correlations can be understood in terms of the\nstochastic dynamics of domain walls, encoded in effective waiting-time\ndistributions with power-law tails. This work defines new possibilities for\nprobing the non-equilibrium and correlated dynamics of disordered and\nheterogeneous media.",
        "positive": "Effects of octahedral tilting on the electronic structure and optical\n  properties of $d^0$ double perovskites $\\mathbf{\\rm A_2ScSbO_6}$\n  ($\\mathbf{\\rm A=Sr, Ca}$): With increasing temperature, ${\\rm Sr}_2{\\rm ScSbO}_6$ undergoes three\nstructural phase transitions at approximately ${\\rm 400K}$, ${\\rm 560K}$ and\n${\\rm 650K}$, leading to the following sequence of phases: $P2_1/n \\rightarrow\nI2/m \\rightarrow I4/m \\rightarrow Fm\\bar{3}m$, making it an ideal candidate to\nstudy the effects of octahedral tilting keeping other parameters fixed. To\nascertain the isolated effects of octahedral distortions, the electronic and\noptical properties of the monoclinic $P2_1/n$ (at room temperature), monoclinic\n$I2/m$ (at ${\\rm 430K}$), tetragonal $I4/m$ (at ${\\rm 613K}$) and the cubic\n$Fm\\bar{3}m$ (at ${\\rm 660K}$) phases have been studied in terms of the\nelectronic structure, dielectric constant, optical conductivity and electron\nenergy loss spectroscopy using density functional theory. ${\\rm Ca}_2{\\rm\nScSbO}_6$, on the other hand, shows only a $P2_1/n$ phase at room temperature\nand its properties have been been compared with the corresponding ${\\rm Sr}$\ncompound. UV-Vis spectroscopic studies of the optical properties of the\nroom-temperature phase of these $d^0$ double perovskite have been performed and\npresence of large direct bandgap for both the compounds have been reported. The\nelectronic bandgaps for the room temperature phases is found to be in good\nagreement with the corresponding experimental values obtained using the\nKubelka-Munk function. Interestingly, in contrast to other Sc-based $d^0$\ndouble perovskites, with increasing octahedral distortions, the effective\n$t_{\\rm 2g}$ bandwidth remains unaffected while the states forming the band\nchange due to changes in unit cell orientation, leading to small effects on the\nelectronic and optical properties."
    },
    {
        "anchor": "Prediction of two-dimensional nodal-line semimetal in a carbon nitride\n  covalent network: Carbon nitride compounds have emerged recently as a prominent member of 2D\nmaterials beyond graphene. The experimental realizations of 2D graphitic carbon\nnitride g-C$_3$N$_4$, nitrogenated holey grahpene C$_2$N, polyaniline C$_3$N\nhave shown their promising potential in energy and environmental applications.\nIn this work, we predict a new type of carbon nitride network with a C$_9$N$_4$\nstoichiometry from first principle calculations. Unlike common C-N compounds\nand covalent organic frameworks (COFs), which are typically insulating,\nsurprisingly C$_9$N$_4$ is found to be a 2D nodal-line semimetal (NLSM). The\nnodal line in C$_9$N$_4$ forms a closed ring centered at $\\Gamma$ point, which\noriginates from the pz orbitals of both C and N. The linear crossing happens\nright at Fermi level contributed by two sets of dispersive Kagome and Dirac\nbands, which is robust due to negligible spin-orbital-coupling (SOC) in C and\nN. Besides, it is revealed that the formation of nodal ring is of accidental\nband degeneracy in nature induced by the chemical potential difference of C and\nN, as validated by a single orbital tight-binding model, rather than protected\nby crystal in-plane mirror symmetry or band topology. Interestingly, a new\nstructure of nodal line, i.e., nodal-cylinder, is found in momentum space for\nAA-stacking C$_9$N$_4$. Our results imply possible functionalization for a\nnovel metal-free C-N covalent network with interesting semimetallic properties.",
        "positive": "Two-dimensional electron systems in ATiO3 perovskites (A = Ca, Ba, Sr):\n  control of orbital hybridization and order: We report the existence of a two-dimensional electron system (2DES) at the\n(001) surface of CaTiO3. Using angle-resolved photoemission spectroscopy, we\nfind a hybridization between the d_xz and d_yz orbitals, not observed in the\n2DESs at the surfaces of other ATiO3 perovskites, e.g. SrTiO3 or BaTiO3. Based\non a comparison of the 2DES properties in these three materials, we show how\nthe electronic structure of the 2DES (bandwidth, orbital order and electron\ndensity) is coupled to different typical lattice distortions in perovskites.\nThe orbital hybridization in orthorhombic CaTiO3 results from the rotation of\nthe oxygen octahedra, which can also occur at the interface of oxide\nheterostructures to compensate strain. More generally, the control of the\norbital order in 2DES by choosing different A-site cations in perovskites\noffers a new gateway towards 2DESs in oxide heterostructures beyond SrTiO3."
    },
    {
        "anchor": "A density functional theory study of the confined soft ellipsoid fluid: A system of soft ellipsoid molecules confined between two planar walls is\nstudied using classical Density Functional Theory (DFT). Both the isotropic and\nnematic phases are considered. The excess free energy is evaluated using two\ndifferent Ansaetze and the intermolecular interaction is incorporated using two\ndifferent direct correlation functions (DCF). The first is a numerical DCF\nobtained from simulations of bulk soft ellipsoid fluids and the second is taken\nfrom Parsons-Lee theory. In both the isotropic and nematic phases the numerical\nDCF gives density and order parameter profiles in reasonable agreement with\nsimulation. The Parsons-Lee DCF also gives reasonable agreement in the\nisotropic phase but poor agreement in the nematic phase.",
        "positive": "High-resolution synchrotron XRD study of Zr-rich compositions of\n  Pb(Zr_xTi_1-x)O_3 (0.525\\leq x \\leq 0.60): evidence for the absence of the\n  rhombohedral phase: Results of Rietveld analysis of the synchrotron XRD data on Pb(Zr_xTi_1-x)O_3\n(PZT) for 0.525\\leqx\\leq0.60 are presented to show the absence of rhombohedral\nphase on the Zr-rich side of the morphotropic phase boundary (MPB). Our results\nreveal that the structure of PZT is monoclinic in the Cm space group for\n0.525\\leq x\\leq 0.60. The nature of the monoclinic distortion changes from\npseudo-tetragonal for 0.525\\leqx\\leq0.54 to pseudo-rhombohedral for x>0.54."
    },
    {
        "anchor": "Provoking topology by octahedral tilting in strained SrNbO$_3$: Transition metal oxides with a wide variety of electronic and magnetic\nproperties offer an extraordinary possibility to be a platform for developing\nfuture electronics based on unconventional quantum phenomena, for instance, the\ntopology. The formation of topologically non-trivial states is related to\ncrystalline symmetry, spin-orbit coupling, and magnetic ordering. Here, we\ndemonstrate how lattice distortions and octahedral rotation in SrNbO$_3$ films\ninduce the band topology. By employing angle-resolved photoemission\nspectroscopy (ARPES) and density functional theory (DFT) calculations, we\nverify the presence of in-phase $a^0a^0c^+$ octahedral rotation in ultra-thin\nSrNbO$_3$ films, which causes the formation of topologically-protected Dirac\nband crossings. Our study illustrates that octahedral engineering can be\neffectively exploited for implanting and controlling quantum topological phases\nin transition metal oxides.",
        "positive": "Martensite plasticity and damage competition in dual-phase steel: A\n  micromechanical experimental-numerical study: Martensite damage in Dual-Phase (DP) steel has been studied extensively, yet,\nthe exact deformation mechanisms that trigger or inhibit damage initiation\nremain mostly unexplored. Whereas generally assumed to be hard and brittle,\nlath martensite in fact deforms in a highly anisotropic manner, showing large\nstrains under favorable habit plane orientations, which is attributed both to\nthe lath morphology and to so-called 'substructure boundary sliding'. Yet, the\ncorrelation (or interplay) between plasticity and damage in lath martensite has\nnot received much attention. Therefore, we raise the question whether these\nsoft martensite plasticity mechanisms can delay or even inhibit damage\ninitiation. We analyze several 'damage-sensitive' martensite notches, {i.e.\nthin contractions of two martensite islands,} by combining several\nstate-of-the-art experimental and analysis methods. Deformations are tracked\nin-situ at the nanoscale, aligned to detailed microstructure maps, and\ncategorised, for each martensite variant, into habit plane or\nout-of-habit-plane slip. In these experiments, strong plasticity (>70%) is\nobserved in martensite notches, enabled by slip along a favorably oriented\nhabit plane, whereas damaged notches have unfavorably oriented habit planes,\nshowing limited pre-damage strains (<10%), carried by out-of-habit-plane slip.\nAdditionally, one-to-one experimentally based Crystal Plasticity (CP)\nsimulations are performed in parallel, employing a recently introduced Enriched\nCP approach which models a soft plasticity mechanism on the variants' habit\nplane. The Enriched CP simulations show considerably lower hydrostatic stresses\nin non-damaged and plastically deforming notches, thereby revealing that the\nsoft habit plane mechanism is key for introducing the high plastic anisotropy\nthat can lead to the inhibition of martensite damage in highly strained\nmartensite notches."
    },
    {
        "anchor": "Mechanism of keyhole pore formation in metal additive manufacturing: Metal additive manufacturing has gained extensive attention from research\ninstitutes and companies to fabricate intricate parts and functionally graded\nmaterials. However, the porosity of the as-built part deteriorates the\nmechanical property and even hinders the further application of metal additive\nmanufacturing. Particularly, the mechanisms of keyhole pores associated with\nthe keyhole fluctuation are not fully understood. To reveal the mechanisms of\nthe keyhole pores formation, we adopt a multiphysics thermal-fluid flow model\nincorporating heat transfer, liquid flow, metal evaporation, Marangoni effect,\nand Darcy's law to simulate the keyhole pore formation process, and the results\nare validated with the in-situ X-ray images. The simulation results present the\ninstant bubble formation due to the keyhole instability and motion of the\ninstant bubble when it pins on the solidification front. Moreover, the unevenly\ndistributed recoil pressure on the keyhole surface is an important factor for\nkeyhole collapse and penetration. Furthermore, comparing the keyhole pore\nformation under different laser scanning speeds shows that the keyhole pore is\nsensitive to the manufacturing parameters. The keyhole fluctuation features and\nenergy absorptivity variation on the rear keyhole wall could be metrics to\nevaluate the likelihood of the keyhole pore formation. Additionally, the\nsimulation under a low ambient pressure shows the feasibility of improving the\nkeyhole stability to reduce and even avoid the formation of keyhole pores.",
        "positive": "Formation of Pt induced Ge atomic nanowires on Pt/Ge(001): a DFT study: Pt deposited onto a Ge(001) surface gives rise to the spontaneous formation\nof atomic nanowires on a mixed Pt-Ge surface after high temperature annealing.\nWe study possible structures of the mixed surface and the nanowires by total\nenergy (density functional theory) calculations. Experimental scanning\ntunneling microscopy images are compared to the calculated local densities of\nstates. On the basis of this comparison and the stability of the structures, we\nconclude that the formation of nanowires is driven by an increased\nconcentration of Pt atoms in the Ge surface layers. Surprisingly, the atomic\nnanowires consist of Ge instead of Pt atoms."
    },
    {
        "anchor": "Magnetic Structural Unit with Convex Geometry: a Building Block Hosting\n  an Exchange-striction-driven Magnetoelectric Coupling: We perform a combined experimental and theoretical study of a magnetic-field\n($B$) induced evolution of magnetic and ferroelectric properties in an\nantiferromagnetic material Pb(TiO)Cu$_4$(PO$_4$)$_4$, whose structure is\ncharacterized by a staggered array of Cu$_4$O$_{12}$ magnetic units with convex\ngeometry known as square cupola. Our experiments show a $B$-induced phase\ntransition from a previously reported low-$B$ linear magnetoelectric phase to a\nnew high-$B$ magnetoelectric phase, which accompanies a 90$^\\circ$ flop of\nelectric polarization and gigantic magnetodielectric effect. Moreover, we\nobserve a $B$-induced sign reversal of ferroelectric polarization in the\nhigh-$B$ phase. Our model and first-principles calculations reveal that the\nobserved complex magnetoelectric behavior is well explained in terms of a\n$B$-dependent electric polarization generated in each Cu$_4$O$_{12}$ unit by\nthe so-called exchange striction mechanism. The present study demonstrates that\nthe materials design based on the magnetic structural unit with convex geometry\ndeserves to be explored for developing strong magnetoelectric couplings.",
        "positive": "Anomalous Proximitized Transport in Metal/Quantum Magnet Heterostructure\n  $\\rm{Bi_{2}Ir_{2}O_{7}/Yb_{2}Ti_{2}O_{7}}$: Fluctuations of quantum spins play a crucial role in the emergence of exotic\nmagnetic phases and excitations. The lack of the charge degree of freedom in\ninsulating quantum magnets, however, precludes such fluctuations from mediating\nelectronic transport. Here we show that the quantum fluctuations of a localized\nfrustrated magnet induce strong proximitized charge transport of the conduction\nelectrons in a synthetic heterostructure comprising an epitaxial\n$\\rm{Bi_{2}Ir_{2}O_{7}}$ ultrathin film on the single crystal of\n$\\rm{Yb_{2}Ti_{2}O_{7}}$. The proximity effects are evidenced by the scaling\nbehavior of the $\\rm{Bi_{2}Ir_{2}O_{7}}$ resistance in correspondance with the\ndynamic scaling of the dynamic spin correlation function of\n$\\rm{Yb_{2}Ti_{2}O_{7}}$, which is a result of quantum fluctuations near a\nmulti-phase quantum critical point. The proximitized transport in\n$\\rm{Bi_{2}Ir_{2}O_{7}}$ can be effectively tuned by magnetic field through\nsuppressing the quantum spin fluctuations as well as inducing transitions via\nmagnetic anisotropy in $\\rm{Yb_{2}Ti_{2}O_{7}}$. Our work establishes a new\npathway for harnessing quantum spin fluctuations in magnetic insulators with\nelectric transport, offering exciting prospects for potential applications in\nthe realm of quantum spintronics."
    },
    {
        "anchor": "Topology and geometry under the nonlinear electromagnetic spotlight: For many materials, a precise knowledge of their dispersion spectra is\ninsufficient to predict their ordered phases and physical responses. Instead,\nthese materials are classified by the geometrical and topological properties of\ntheir wavefunctions. A key challenge is to identify and implement experiments\nthat probe or control these quantum properties. In this review, we describe\nrecent progress in this direction, focusing on nonlinear electromagnetic\nresponses that arise directly from quantum geometry and topology. We give an\noverview of the field by discussing new theoretical ideas, groundbreaking\nexperiments, and the novel materials that drive them. We conclude by discussing\nhow these techniques can be combined with new device architectures to uncover,\nprobe, and ultimately control novel quantum phases with emergent topological\nand correlated properties.",
        "positive": "Thermal expansion and pressure effect in MnWO4: MnWO4 has attracted attention because of its ferroelectric property induced\nby frustrated helical spin order. Strong spin-lattice interaction is necessary\nto explain ferroelectricity associated with this type of magnetic order.We have\nconducted thermal expansion measurements along the a, b, c axes revealing the\nexistence of strong anisotropic lattice anomalies at T1=7.8 K, the temperature\nof the magnetic lock-in transition into a commensurate low-temperature\n(reentrant paraelectric) phase. The effect of hydrostatic pressure up to 1.8\nGPa on the FE phase is investigated by measuring the dielectric constant and\nthe FE polarization. The low- temperature commensurate and paraelectric phase\nis stabilized and the stability range of the ferroelectric phase is diminished\nunder pressure."
    },
    {
        "anchor": "Improved scintillation proportionality and energy resolution of LaBr3:Ce\n  at 80K: Using highly monochromatic synchrotron X-rays in the energy range from 10.5\nkeV to 100 keV the temperature dependence of nonproportionality and energy\nresolution of LaBr3 scintillators doped with 5% Ce3+ were studied at 80K, 295K,\nand 450K. Improvement of the proportionality and better energy resolution was\nobserved on lowering the temperature. This effect suggests that the already\noutstanding energy resolution of LaBr3:Ce can be improved even further. It also\nmay provide new clues to better understand the processes that cause\nnonproportionality of inorganic scintillator response.",
        "positive": "One-dimensionality of the spin-polarized surface conduction and valence\n  bands of quasi-one-dimensional Bi chains on GaSb(110)-(2$\\times$1): Surface electronic structure and its one-dimensionality above and below the\nFermi level ($E_{\\rm F}$) were surveyed on the Bi/GaSb(110)-(2$\\times$1)\nsurface hosting quasi-one-dimensional (Q1D) Bi chains, using conventional\n(one-photon) and two-photon angle-resolved photoelectron spectroscopy (ARPES)\nand theoretical calculations. ARPES results reveal that the Q1D electronic\nstates are within the projected bulk bandgap. Circular dichroism of two-photon\nARPES and density-functional-theory calculation indicate clear spin and orbital\npolarization of the surface states consistent with the giant sizes of\nRashba-type SOI, derived from the strong contribution of heavy Bi atoms. The\nsurface conduction band above $E_{\\rm F}$ forms a nearly straight\nconstant-energy contour, suggesting its suitability for application in further\nstudies of one-dimensional electronic systems with strong SOI. A tight-binding\nmodel calculation based on the obtained surface electronic structure\nsuccessfully reproduces the surface band dispersions and predicts possible one-\nto two-dimensional crossover in the temperature range of 60--100~K."
    },
    {
        "anchor": "Microstructural evolution during ageing of Al-Cu-Li-x alloys: In this study atom probe tomography was used to investigate the\nmicrostructure of AA2198 (Al-1.35Cu-3.55Li-0.29Mg-0.08Ag) over a range of\nageing conditions to examine the evolution of phases in the alloy, in\nparticular aiming to reveal the nucleation mechanism of the strengthening T1\nphase, which has been under debate for decades. T1 precursor phases were\nobserved from early ageing, a significant number of which were connected to\nsolute-enriched dislocations. Ag and Mg segregation to T1 interfaces was\nconvincingly observed when the plates were oriented perpendicular to the\nprobing direction, which is the condition under which the spatial resolution of\nthe atom probe data is highest.",
        "positive": "What Causes High Resistivity in CdTe: CdTe can be made semi-insulating by shallow donor doping. This is routinely\ndone to obtain high resistivity in CdTe-based radiation detectors. However, it\nis widely believed that the high resistivity in CdTe is due to the Fermi level\npinning by native deep donors. The model based on shallow donor compensation of\nnative acceptors was dismissed based on the assumption that it is practically\nimpossible to control the shallow donor doping level so precisely that the free\ncarrier density can be brought below the desired value suitable for radiation\ndetection applications. In this paper, we present our calculations on carrier\nstatistics and energetics of shallow donors and native defects in CdTe. Our\nresults show that the shallow donor can be used to reliably obtain high\nresistivity in CdTe. Since radiation detection applications require both high\nresistivity and good carrier transport, one should generally use shallow donors\nand shallow acceptors for carrier compensation and avoid deep centers that are\neffective carrier traps."
    },
    {
        "anchor": "Interface dominated biferroic La0.6Sr0.4MnO3/0.7Pb(Mg0.33Nb0.66)O3\n  0.3PbTiO3 epitaxial superlattices: Superlattices composed of ferromagnetic La0.6Sr0.4MnO3 and ferroelectric\n0.7Pb(Mg0,33Nb0.66)O3 0.3(PbTiO3) layers were fabricated on (100) LaAlO3\nsubstrates by pulsed laser deposition technique. Ferromagnetic and frequency\nindependent ferroelectric hysteresis characteristics established the biferroic\nnature of the superlattices. Influence of magnetic field was observed in tuning\nthe P-E characteristics of the superlattices. Similar effect was observed on\napplication of a high DC electric field to the samples. The nature of the\nobserved ferroelectric properties and their modulation by applied magnetic and\nelectric fields were thus discussed in connection to existence of dielectric\npassive layers at the ferroelectric/ferromagnetic interface.",
        "positive": "Influence of particle shape on sheared dense granular media: We study by means of molecular dynamics simulations of periodic shear cells,\nthe influence of particle shape on the global mechanical behavior of dense\ngranular media. Results at macro-mechanical level show that for large shear\ndeformation samples with elongated particles, independent of their initial\norientation, reach the same stationary value for both shear force and void\nratio. At the micro-mechanical level the stress, the fabric and the inertia\ntensors of the particles are used to study the evolution of the media. In the\ncase of isotropic particles the direction of the principal axis of the fabric\ntensor is aligned with the one of the principal stress, while for elongated\nparticles the fabric orientation is strongly dependent on the orientation of\nthe particles. The shear band width is shown to depend on the particle shape\ndue to the tendency of elongated particles to preferential orientations and\nless rotation."
    },
    {
        "anchor": "Metastable giant moments in Gd-implanted GaN, Si, and sapphire: We report on Gd ion implantation and magnetic characterization of GaN films\non sapphire substrates and of bare sapphire and Si substrates to shed light on\nthe mechanism underlying the induced magnetism upon Gd ion implantation. For\nall three hosts, giant magnetic moments per Gd ion were observed at\ntemperatures of 5 through 300 K. The maximum moment per Gd in GaN was 1800\nmu_B, while the moments in Gd-implanted Si and sapphire were only slightly\nsmaller. The apparent induced ferromagnetic response was found to be\nmetastable, disappearing after on the order of 50 days at room temperature,\nexcept for the implanted sapphire. We argue that our findings support a\ndefect-based picture of magnetism in Gd-implanted semiconductors and\ninsulators.",
        "positive": "Transforming carbon nanotubes by silylation: An ab initio study: We use ab initio density functional calculations to study the chemical\nfunctionalization of single-wall carbon nanotubes and graphene monolayers by\nsilyl (SiH3) radicals and hydrogen. We find that silyl radicals form strong\ncovalent bonds with graphene and nanotube walls, causing local structural\nrelaxations that enhance the sp3 character of these graphitic nanostructures.\nSilylation transforms all carbon nanotubes into semiconductors, independent of\ntheir chirality. Calculated vibrational spectra suggest that specific frequency\nshifts can be used as a signature of successful silylation."
    },
    {
        "anchor": "Structural modification in Au/Si(100) system: Role of surface oxide and\n  vacuum level: To understand surface structural modifications for Au/Si (100) system, a thin\ngold film of ~2.0 nm was deposited under ultra high vacuum (UHV) condition on\nreconstructed Si surfaces using molecular beam epitaxy (MBE). Post annealing\nwas done at 500{\\deg}C in three different vacuum conditions: (1) low vacuum\n(LV) furnace (10-2 mbar), (2) UHV (10-10 mbar) (MBE chamber), (3) high vacuum\n(HV) chamber. The variation in the overall shape of the gold nanostructures and\nfiner changes at the edges, like rounding of corners has been reported in this\nwork. Although well aligned nano rectangles were formed in both HV and LV\ncases, corner rounding is more prominent in LV case. Furthermore in UHV case,\nrandom structures were formed having sharp corners. In all the above three\ncases, samples were exposed to air (for half an hour) before annealing. To\nstudy the effect of surface oxide, in-situ annealing inside UHV-MBE chamber was\ndone without exposing to air. Well aligned rectangles with sharp corners (no\ncorner rounding) were formed. The details about the role of surface oxides in\nthe corner rounding process are discussed.",
        "positive": "Interfacial Energy of Copper Clusters in Fe-Si-B-Nb-Cu alloys: Using a combination of numerical simulations and atom-probe tomography\nexperiments, we determine the interfacial energy of Cu nanocrystals\nprecipitated within the amorphous matrix of FINEMET (molar composition\nFe72.89Si16.21B6.90Nb3Cu1). Specifically, we use the Langer-Schwartz model\nimplemented in the software Thermocalc to carry out parametric simulations of\ngrowth and coarsening of Cu clusters for different interface energies. We have\ncarried out atom-probe tomography (APT) experiments to determine the interface\nenergy as the value for which the simulated particle size distribution best\nmatches the experimental data. This combination of APT and precipitation\nmodeling can be applied to other nanocrystals precipitated within amorphous\nmatrices."
    },
    {
        "anchor": "Modification of titanium and titanium dioxide surfaces by ion\n  implantation: combined XPS and DFT study: The results of XPS measurements (core levels and valence bands) of P+, Ca+,\nP+Ca+ and Ca+P+ ion implanted (E=30 keV, D=1x1017 cm-2) commercially pure\ntitanium (cp-Ti) and first-principles density functional theory (DFT)\ncalculations demonstrates formation of various structural defects in titanium\ndioxide films formed on the surface of implanted materials. We have found that\nfor double implantation (Ti:P+,Ca+ and Ti:Ca+,P+) the outermost surface layer\nformed mainly by Ca and P, respectively, i.e. the implantation sequence is very\nimportant. The DFT calculations show that under P+ and Ca+P+ ion implantation\nthe formation energies for both cation (P-Ti) and anion (P-O) substitutions are\ncomparable which can induce the creation of [PO4]3- and Ti-P species. For Ca+\nand P+Ca+-ion implantation the calculated formation energies correspond to\nCa2+-Ti4+ cation substitution. This conclusion is in agreement with XPS Ca 2p\nand Ti 2p core levels and valence band measurements and DFT calculations of\nelectronic structure of related compounds. The conversion of implanted ions to\nCa2+ and [PO4]3- species provides a good biocompatibility of cp-Ti for further\nformation of hydroxyapatite.",
        "positive": "Temperature-induced changes in the magnetism of Laves phase\n  rare-earth--iron intermetallics by ab~initio calculations: Laves RFe2 compounds, where R is a rare earth, exhibit technologically\nrelevant properties associated with the interplay between their lattice\ngeometry and magnetism. We apply ab~initio calculations to explore how magnetic\nproperties of Fe in RFe2 systems vary with temperature. We found that the ratio\nbetween the orbital magnetic moment m_orb and the spin magnetic moment m_spin\nincreases with increasing temperature for YFe2, GdFe2, TbFe2, DyFe2, and HoFe2.\nThis increase is significant and it should be experimentally observable by\nmeans of x-ray magnetic circular dichroism. We conjecture that the predicted\nincrease of the m_orb/m_spin ratio with temperature is linked to the reduction\nof hybridization between same-spin-channel states of atoms with fluctuating\nmagnetic moments and to the associated increase of their atomic-like character."
    },
    {
        "anchor": "Conductance of a single molecule anchored by an isocyanide substituent\n  to gold electrodes: The effect of anchoring group on the electrical conductance of a single\nmolecule bridging two Au electrodes was studied using di-substituted\n(isocyanide (CN-), thiol (S-) or cyanide (NC-)) benzene. The conductance of a\nsingle Au/1,4-diisocyanobenzene/Au junction anchored by isocyanide via a C atom\n(junction with the Au-CN bond) was $3 \\times 10 ^{-3} G_{0}$ ($2e^{2}/h$). The\nvalue was comparable to $4 \\times 10 ^{-3} G_{0}$ of a single\nAu/1,4-benzenedithiol/Au junction with the Au-S bond. The\nAu/1,4-dicyanobenzene/Au molecular junction with the Au-NC bond did not show\nwell-defined conductance values. The metal-molecule bond strength was estimated\nby the distance over which the molecular junction was stretched before\nbreakdown. The stretched length of the molecular junction with the Au-CN bond\nwas comparable to that of the Au junction, indicating that the Au-CN bond was\nstronger than the Au-Au bond.",
        "positive": "Tunable magneto-granular phononic crystals: This paper reports on the study of the dynamics of 1D magneto-granular\nphononic crystals composed of a chain of spherical steel beads inside a\nproperly designed magnetic field. This field is induced by an array of\npermanent magnets, located in a holder at a given distance from the chain. The\ntheoretical and experimental results of the band gap structure are displayed,\nincluding all six degrees of freedom for the beads, i.e. three translations and\nthree rotations. Experimental evidence of transverse-rotational modes of\npropagation is pre- sented; moreover, by changing the strength of the magnetic\nfield, the dynamic response of the granular chain is tuned. The combination of\nnon-contact tunability with the potentially strong nonlinear behavior of gran-\nular systems ensures the suitability of magneto-granular phononic crystals as\nnonlinear, tunable mechanical metamaterials for use in controlling elastic wave\npropagation."
    },
    {
        "anchor": "One nanometer HfO$_2$-based ferroelectric tunnel junctions on silicon: In ferroelectric materials, spontaneous symmetry breaking leads to a\nswitchable electric polarization, which offers significant promise for\nnonvolatile memories. In particular, ferroelectric tunnel junctions (FTJs) have\nemerged as a new resistive switching memory which exploit\npolarization-dependent tunnel current across a thin ferroelectric barrier. Here\nwe demonstrate FTJs with CMOS-compatible Zr-doped HfO$_2$ (Zr:HfO$_2$)\nferroelectric barriers of just 1 nm thickness, grown by atomic layer deposition\non silicon. These 1 nm Zr:HfO$_2$ tunnel junctions exhibit large\npolarization-driven electroresistance (19000$\\%$), the largest value reported\nfor HfO$_2$-based FTJs. In addition, due to just a 1 nm ferroelectric barrier,\nthese junctions provide large tunnel current (> 1 A/cm$^2$) at low read\nvoltage, orders of magnitude larger than reported thicker HfO$_2$-based FTJs.\nTherefore, our proof-of-principle demonstration provides an approach to\nsimultaneously overcome three major drawbacks of prototypical FTJs: a\nSi-compatible ultrathin ferroelectric, large electroresistance, and large read\ncurrent for high-speed operation.",
        "positive": "Localization of elastic deformation in strongly anisotropic, porous,\n  linear materials with periodic microstructures: exact solutions and dilute\n  expansions: Exact solutions are derived for the problem of a two-dimensional, infinitely\nanisotropic, linear-elastic medium containing a periodic lattice of voids. The\nmatrix material possesses either one infinitely soft, or one infinitely hard\nloading direction, which induces localized (singular) field configurations. The\neffective elastic moduli are computed as functions of the porosity in each\ncase. Their dilute expansions feature half-integer powers of the porosity,\nwhich can be correlated to the localized field patterns. Statistical\ncharacterizations of the fields, such as their first moments and their\nhistograms are provided, with particular emphasis on the singularities of the\nlatter. The behavior of the system near the void close packing fraction is also\ninvestigated. The results of this work shed light on corresponding results for\nstrongly nonlinear porous media, which have been obtained recently by means of\nthe ``second-order'' homogenization method, and where the dilute estimates also\nexhibit fractional powers of the porosity."
    },
    {
        "anchor": "Systematic Design of Antireflection Coating for Semi-infinite\n  One-dimensional Photonic Crystals Using Bloch Wave Expansion: We present a systematic method for designing a perfect antireflection coating\n(ARC) for a semi-infinite one-dimensional (1D) photonic crystal (PC) with an\narbitrary unit cell. We use Bloch wave expansion and time reversal symmetry,\nwhich leads exactly to analytic formulas of structural parameters for the ARC\nand renormalized Fresnel coefficients of the PC. Surface immittance (admittance\nand impedance) matching plays an essential role in designing the ARC of 1D\nPC's, which is shown together with a practical example.",
        "positive": "Phase-field modeling of equilibrium precipitate shapes under the\n  influence of coherency stresses: Coherency misfit stresses and their related anisotropies are known to\ninfluence the equilibrium shapes of precipitates. Additionally, mechanical\nproperties of the alloys are also dependent on the shapes of the precipitates.\nTherefore, in order to investigate the mechanical response of a material which\nundergoes precipitation during heat treatment, it is important to derive the\nrange of precipitate shapes that evolve. In this regard, several studies have\nbeen conducted in the past using sharp interface approaches where the influence\nof elastic energy anisotropy on the precipitate shapes has been investigated.\nIn this paper, we propose a diffuse interface approach which allows us to\nminimize grid-anisotropy related issues applicable in sharp-interface methods.\nIn this context, we introduce a novel phase-field method where we minimize the\nfunctional consisting of the elastic and surface energy contributions while\npreserving the precipitate volume. Using this method we reproduce the\nshape-bifurcation diagrams for the cases of pure dilatational misfit that have\nbeen studied previously using sharp interface methods and then extend them to\ninclude interfacial energy anisotropy with different anisotropy strengths which\nhas not been a part of previous sharp-interface models. While we restrict\nourselves to cubic anisotropies in both elastic and interfacial energies in\nthis study, the model is generic enough to handle any combination of\nanisotropies in both the bulk and interfacial terms. Further, we have examined\nthe influence of asymmetry in dilatational misfit strains along with\ninterfacial energy anisotropy on precipitate morphologies."
    },
    {
        "anchor": "Ambipolar diffusion of photo-excited carriers in bulk GaAs: The ambipolar carrier diffusion in bulk GaAs is studied by using an ultrafast\npump-probe technique with a high spatial resolution. Carriers with a point-like\nspatial profile are excited by a tightly focused pump laser pulse. The\nspatiotemporal dynamics of the carriers are monitored by a time-delayed and\nspatially scanned probe pulse. Ambipolar diffusion coefficients are deduced\nfrom linear fits to the expansion of the area of the profiles, and are found to\ndecrease from about 170~$\\mathrm{cm}^2 \\mathrm{s}^{-1}$ at 10 K to about\n20~$\\mathrm{cm}^2 \\mathrm{s}^{-1}$ at room temperature. Our results are\nconsistent with those deduced from the previously measured mobilities.",
        "positive": "Effect of Aspect Ratio and Boundary Conditions in Modeling Shape Memory\n  Alloy Nanostructures with 3D Coupled Dynamic Phase-Field Models: The behavior of shape memory alloy (SMA) nanostructures is influenced by\nstrain rate and temperature evolution during dynamic loading. The coupling\nbetween temperature, strain and strain rate effects is essential to capture\ninherent thermo-mechanical behavior in SMAs. In this paper, we propose a new\nfully coupled thermo-mechanical 3D phase-field model that accounts for two-way\ncoupling between mechanical (or structural) and thermal physics. The 3D model\nprovides a realistic description of the properties of SMAs nanostructures. We\nuse the strain-based Ginzburg-Landau potential for cubic-to-tetragonal phase\ntransformations. The variational formulation of the developed model is\nimplemented in the isogeometric analysis framework to overcome numerical\nchallenges. We have observed a complete disappearance of the out-of-plane\nmartensitic variant in a very high aspect ratio SMA domain as well as the\npresence of three variants in equal portions in a low aspect ratio SMA domain.\nThe sensitive dependence of different boundary conditions on the microstructure\nmorphology has been examined energetically. The tensile tests on a rectangular\nprism nanowires, using the displacement based loading, demonstrate the shape\nmemory effect and pseudoelastic behavior. We have also observed that higher\nstrain rates, as well as the lower aspect ratio domains, resulting in high\nyield stress and phase transformations occur at higher stress during dynamic\naxial loading. The simulation results using the developed model are in\nqualitative agreement with the numerical and experimental results from the\nliterature."
    },
    {
        "anchor": "Artificial piezoelectricity in centrosymmetric SrTiO3: Defect engineering is an effective and powerful tool to control existing\nmaterial properties and create completely new ones, which are\nsymmetry-forbidden in a defect-free crystal. This letter reports on the\ncreation of piezoelectrically active near-surface layer of centrosymmetric\nSrTiO3, modified by the electric field-induced migration of oxygen vacancies.\nWe provide the unequivocal proof of piezoelectricity through the stroboscopic\ntime-resolved X-ray diffraction under alternating electric field. The magnitude\nof the discovered piezoelectric effect is comparable with the bulk\npiezoelectric effect in commercial ferroelectric materials. Such artificially\nformed defect-mediated piezoelectricity can be important as an alternative road\nfor smart materials design.",
        "positive": "Thermal Desorption of H2O-Ice: From Nanoscale Films to the Bulk: Desorption of H2O films ranging from 53 nanometres to 101 micrometre\nthicknesses have been investigated using a quartz-crystal microbalance (QCM)\nand temperature-programmed desorption. Three desorption stages are observed\nbelonging to amorphous solid water (ASW), stacking disordered ice I (ice Isd),\nand hexagonal ice I (ice Ih). The desorption of ASW is only visible for the >10\nmicrometre films and is separated from the ice I desorption by 10-15 K and has\nan associated desorption energy of 64 kJ mol-1. The desorption energy of the 53\nnanometre film was found to be near 50 kJ mol-1 as also noted in the\nliterature, but with increasing film thickness the desorption energy of ice I\nrises until reaching a plateau around 65-70 kJ mol-1. The reason for the\nincreased desorption energy is suggested to be due to molecules unable to\ndesorb due to the thick covering layer of H2O and possibly re-adsorption.\nBefore complete desorption of ice I which occurs around 220 K for the 100\nmicrometre film, a two-stage ice I desorption is observed with the QCM for the\n10 and 20 micrometre films near 200 K. This event corresponds to the desorption\nof ice Isd as corroborated by X-ray diffraction patterns collected upon heating\nfrom 92-260 K at ambient pressure. Cubic ice is not observed as is commonly\nstated in the literature as resulting from the crystallisation of ASW.\nTherefore, ice Isd is the correct terminology for the initial crystallisation\nproduct of ASW."
    },
    {
        "anchor": "Antiferromagnetism in two-dimensional materials: progress and\n  computational challenges: We present a perspective on the status of antiferromagnetism in\ntwo-dimensional (2D) materials. Various types of spin-compensated orders are\ndiscussed and include non-collinear order, spin spirals and altermagnetism.\nSpin-orbit effects ultimately determine, whether compounds exhibit long range\norder, Kosterlitz-Thouless physics, or multiferroic properties and we discuss\nthe basic magnetic prototypes that may arise in 2D materials depending on the\nmagnetic anisotropy and ordering vector. A summary of 2D antiferromagnets that\nhave been characterized experimentally is provided - with particular emphasis\non magnetic anisotropies and Neel temperatures. We then outline the ingredients\nneeded to describe the magnetic properties using density functional theory. In\nparticular, the systematic determination of magnetic ground states from the\ngeneralized Bloch theorem and the magnetic force theorem, which may be used to\ncalculate magnetic excitations from the Heisenberg model with parameters\ndetermined from first principles. The methods are exemplified by application to\nthe monolayer helimagnet NiBr$_2$. Finally, we present a summary of predicted\nand prospective 2D antiferromagnets and discuss the challenges associated with\nthe prediction of N\\'eel temperatures from first principles.",
        "positive": "First-principles study on the electronic structure of\n  Pb$_{10-x}$Cu$_x$(PO$_4$)$_6$O ($x$=0, 1): Recently, Lee et al. reported the experimental discovery of room-temperature\nambient-pressure superconductivity in a Cu-doped lead-apatite (LK-99)\n(arXiv:2307.12008, arXiv:2307.12037). Remarkably, the superconductivity\npersists up to 400 K at ambient pressure. Despite strong experimental evidence,\nthe electronic structure of LK-99 has not yet been studied. Here, we\ninvestigate the electronic structures of LK-99 and its parent compound using\nfirst-principles calculations, aiming to elucidate the doping effects of Cu.\nOur results reveal that the parent compound Pb$_{10}$(PO$_4$)$_6$O is an\ninsulator, while Cu doping induces an insulator-metal transition and thus\nvolume contraction. The band structures of LK-99 around the Fermi level are\nfeatured by a half-filled flat band and a fully-occupied flat band. These two\nflat bands arise from both the $2p$ orbitals of $1/4$-occupied O atoms and the\nhybridization of the $3d$ orbitals of Cu with the $2p$ orbitals of its\nnearest-neighboring O atoms. Interestingly, we observe four van Hove\nsingularities on these two flat bands. Furthermore, we show that the flat band\nstructures can be tuned by including electronic correlation effects or by\ndoping different elements. We find that among the considered doping elements\n(Ni, Cu, Zn, Ag, and Au), both Ni and Zn doping result in the gap opening,\nwhereas Au exhibits doping effects more similar to Cu than Ag. Our work\nprovides a foundation for future studies on the role of unique electronic\nstructures of LK-99 in superconductivity."
    },
    {
        "anchor": "Extensions of the time-dependent density functional based tight-binding\n  approach: The time-dependent density functional based tight-binding (TD-DFTB) approach\nis generalized to account for fractional occupations. In addition, an on-site\ncorrection leads to marked qualitative and quantitative improvements over the\noriginal method. Especially, the known failure of TD-DFTB for the description\nof \\sigma -> \\pi* and n -> \\pi* excitations is overcome. Benchmark calculations\non a large set of organic molecules also indicate a better description of\ntriplet states. The accuracy of the revised TD-DFTB method is found to be\nsimilar to first principles TD-DFT calculations at a highly reduced\ncomputational cost. As a side issue, we also discuss the generalization of the\nTD-DFTB method to spin-polarized systems. In contrast to an earlier study\n[Trani et al., JCTC 7 3304 (2011)], we obtain a formalism that is fully\nconsistent with the use of local exchange-correlation functionals in the ground\nstate DFTB method.",
        "positive": "Energy, phonon, and dynamic stability criteria of 2d materials: First-principles calculations have become a powerful tool to exclude the\nEdisonian approach in search of novel 2d materials. However, no universal\nfirst-principles criteria to examine the realizability of hypothetical 2d\nmaterials have been established in the literature yet. Because of this, and\nsince the calculations are always performed in an artificial simulation\nenvironment, one can unintentionally study compounds that do not exist in the\nexperiments. Although investigations of physics and chemistry of unrealizable\nmaterials can provide some fundamental knowledge, the discussion of their\napplications can mislead experimentalists for years and increase the gap\nbetween experimental and theoretical research. By analyzing energy convex hull,\nphonon spectra, and structure evolution during ab initio molecular dynamics\nsimulations for a range of synthesized and recently proposed 2d materials, we\nconstruct energy, phonon, and dynamic stability filters which need to be\nsatisfied before proposing novel 2d compounds. We demonstrate the power of the\nsuggested filters for several selected 2d systems, revealing that some of them\ncannot be ever realized experimentally."
    },
    {
        "anchor": "Twin boundary reversibility characteristics in \u03b1-Fe: Understanding the grain boundary deformation dynamics is very crucial to\ndesigning materials with stable microstructures. With this quest, the\ndeformation behavior of coherent twin boundary under cyclic shear loading has\nbeen studied in {\\alpha}-Fe using molecular dynamics simulations to understand\nthe influence of strain amplitude and temperature. Twin boundary exhibited\nshear coupled migration along with cyclic irreversibility character at lower\ntemperatures and gained almost perfect reversibility at higher temperatures of\naround 1500 K. TB exhibited more sliding than migration with an increase in\ntemperature. The stress associated with the migration of twins was observed to\nfluctuate around its average value. This was caused by layer by layer\npropagation of twin boundary through the activity of 1/6 <111> = 1/12 <111> +\n1/12 <111> type edge partial dislocations on \"\\{\"112\"\\}\" twin plane. Complete\ntwin reversibility and complex TB migration were noticed in the presence of\nmultiple parallel twin nanowires. Twin migration was observed at the larger\nsize nanowires with a proper combination of boundary conditions and strain\nrates; otherwise, it was absent. The influence of shear strain amplitude in\noffsetting the twin boundary was found to be minimal.",
        "positive": "Robust charge and magnetic order under electric field and current in the\n  multiferroic LuFe(2)O(4): We performed elastic neutron scattering measurements on the charge- and\nmagnetically-ordered multiferroic material LuFe(2)O(4). An external electric\nfield along the [001] direction with strength up to 20 kV/cm applied at low\ntemperature (~100 K) does not affect either the charge or magnetic structure.\nAt higher temperatures (~360 K), before the transition to three-dimensional\ncharge-ordered state, the resistivity of the sample is low, and an electric\ncurrent was applied instead. A reduction of the charge and magnetic peak\nintensities occurs when the sample is cooled under a constant electric current.\nHowever, after calibrating the real sample temperature using its own\nresistance-temperature curve, we show that the actual sample temperature is\nhigher than the thermometer readings, and the \"intensity reduction\" is entirely\ndue to internal sample heating by the applied current. Our results suggest that\nthe charge and magnetic orders in LuFe(2)O(4) are unaffected by the application\nof external electric field/current, and previously observed electric\nfield/current effects can be naturally explained by internal sample heating."
    },
    {
        "anchor": "Simplicial Message Passing for Chemical Property Prediction: Recently, message-passing Neural networks (MPNN) provide a promising tool for\ndealing with molecular graphs and have achieved remarkable success in\nfacilitating the discovery and materials design with desired properties.\nHowever, the classical MPNN methods also suffer from a limitation in capturing\nthe strong topological information hidden in molecular structures, such as\nnonisomorphic graphs. To address this problem, this work proposes a Simplicial\nMessage Passing (SMP) framework to better capture the topological information\nfrom molecules, which can break through the limitation within the vanilla\nmessage-passing paradigm. In SMP, a generalized message-passing framework is\nestablished for aggregating the information from arbitrary-order simplicial\ncomplex, and a hierarchical structure is elaborated to allow information\nexchange between different order simplices. We apply the SMP framework within\ndeep learning architectures for quantum-chemical properties prediction and\nachieve state-of-the-art results. The results show that compared to traditional\nMPNN, involving higher-order simplex can better capture the complex structure\nof molecules and substantially enhance the performance of tasks. The SMP-based\nmodel can provide a generalized framework for GNNs and aid in the discovery and\ndesign of materials with tailored properties for various applications.",
        "positive": "Grain boundary ferromagnetism in vanadium-doped In$_2$O$_3$ thin films: Room temperature ferromagnetism was observed in In$_2$O$_3 thin films doped\nwith 5 at.% vanadium, prepared by pulsed laser deposition at substrate\ntemperatures ranging from 300 to 600 $\\,^{\\circ}{\\rm C}$. X-ray absorption fine\nstructure measurement indicated that vanadium was substitutionally dissolved in\nthe In$_2$O$_3$ host lattice, thus excluding the existence of secondary phases\nof vanadium compounds. Magnetic measurements based on SQUID magnetometry and\nmagnetic circular dichroism confirm that the magnetism is at grain boundaries\nand also in the grains. The overall magnetization originates from the competing\neffects between grains and grain boundaries."
    },
    {
        "anchor": "Helicity dependent photocurrent in electrically gated (Bi,Sb)_2Te_3 thin\n  films: Circularly polarized photons are known to generate a directional\nhelicity-dependent photocurrent in three-dimensional topological insulators at\nroom temperature. Surprisingly, the phenomenon is readily observed at photon\nenergies that excite electrons to states far above the spin-momentum locked\nDirac cone and the underlying mechanism for the helicity-dependent photocurrent\nis still not understood. We resolve the puzzle through a comprehensive study of\nthe helicity-dependent photocurrent in (Bi,Sb)_2Te_3 thin films as a function\nof the incidence angle of the optical excitation, its wavelength, and the\ngate-tuned chemical potential. Our observations allow us to unambiguously\nidentify the circular photo-galvanic effect as the dominant mechanism for the\nhelicity-dependent photocurrent. Additionally, we use an analytical calculation\nto relate the directional nature of the photocurrent to asymmetric optical\ntransitions between the topological surface states and bulk bands. The insights\nwe obtain are important for engineering opto-spintronic devices that rely on\noptical steering of spin and charge currents.",
        "positive": "Spinodal superlattices of topological insulators: Spinodal decomposition is proposed for stabilizing self-assembled interfaces\nbetween topological insulators (TIs) by combining layers of iso-structural and\niso-valent TlBi$X_2$ ($X$=S, Se, Te) materials. The composition range for\ngapless states is addressed concurrently to the study of thermodynamically\ndriven boundaries. By tailoring composition, the TlBiS$_2$-TlBiTe$_2$ system\nmight produce both spinodal superlattices and two dimensional eutectic\nmicrostructures, either concurrently or separately. The dimensions and\ntopological nature of the metallic channels are determined by following the\nspatial distribution of the charge density and the spin-texture. The results\nvalidate the proof of concept for obtaining spontaneously forming\ntwo-dimensional TI-conducting channels embedded into three-dimensional\ninsulating environments without any vacuum interfaces. Since spinodal\ndecomposition is a controllable kinetic phenomenon, its leverage could become\nthe long-sought enabler for effective TI technological deployment."
    },
    {
        "anchor": "Violet emission from bulk Si prompted by surface plasmon polaritons: Silicon has been long known as a poor light emitter due to its indirect band\ngap and strong phonon-assisted decay of the excited states. Nevertheless, we\nhave revealed efficient quasi-monochromatic photoluminescence at 368 nm from\nbulk silicon in the near-violet spectral range of the interband transition\nSiE{\\Gamma}1 even at room temperature. Optical and electron spectroscopy\nexperiments showed a clear relation of the emission to a surface plasmon\npolariton (SPP) located on the SiO/Si interface. The presented results\ndemonstrate that the unveiled luminescence is an effect of creation and decay\nof the SPP being a mixture of the surface plasmon, light, and the bulk\ninterband transition. The SPP evolves in the silicon layer with a thickness of\nthe order of the near-violet wave penetration depth (~80 nm) and is\ncharacterized by high excitation amplitude due to its hybrid nature. The effect\nseems to be easily applicable in developing near-violet light sources based on\nthe existing Si-technology.",
        "positive": "Macroscopic description of the diffusion of interstitial impurity atoms\n  considering the influence of elastic stress on the drift of interstitial\n  species: The diffusion equation for nonequilibrium interstitial impurity atoms taking\ninto account their charge states and drift of all mobile interstitial species\nin the built-in electric field and in the field of elastic stress was obtained.\nThe obtained generalized equation is equivalent to the set of diffusion\nequations written for the interstitial impurity atoms in each individual charge\nstate. Due to a number of the characteristic features the generalized equation\nis more convenient for numerical solution than the original system of separate\ndiffusion equations. On this basis, the macroscopic description of\nstress-mediated impurity diffusion due to a kick-out mechanism was obtained. It\nis supposed that the interstitial impurity atom makes a number of jumps before\nconversion to the substitutional position. At the same time, a local\nequilibrium prevails between substitutionally dissolved impurity atoms,\nnonequilibrium self-interstitials, and interstitial impurity atoms. Also, the\nderived equation for impurity diffusion due to the kick-out mechanism takes\ninto account all charge states of interstitial impurity atoms as well as drift\nof interstitial species in the electric field and in the field of elastic\nstress. Moreover, this equation exactly matches the equation of stress-mediated\nimpurity diffusion due to generation, migration, and dissociation of the\nequilibrium pairs \"impurity atom - self-interstitial\"."
    },
    {
        "anchor": "Ultrafast terahertz field control of the emergent magnetic and\n  electronic interactions at oxide interfaces: Ultrafast electric-field control of emergent electronic and magnetic states\nat oxide interfaces offers exciting prospects for the development of new\ngenerations of energy-efficient devices. Here, we demonstrate that the\nelectronic structure and emergent ferromagnetic interfacial state in epitaxial\nLaNiO3/CaMnO3 superlattices can be effectively controlled using intense\nsingle-cycle THz electric-field pulses. We employ a combination of\npolarization-dependent X-ray absorption spectroscopy with magnetic circular\ndichroism and X-ray resonant magnetic reflectivity to measure a detailed\nmagneto-optical profile and thickness of the ferromagnetic interfacial layer.\nThen, we use time-resolved and temperature-dependent magneto-optical Kerr\neffect, along with transient optical reflectivity and transmissivity\nmeasurements, to disentangle multiple correlated electronic and magnetic\nprocesses driven by ultrafast high-field (~1 MV/cm) THz pulses. These processes\ninclude an initial sub-picosecond electronic response, consistent with\nnon-equilibrium Joule heating; a rapid (~270 fs) demagnetization of the\nferromagnetic interfacial layer, driven by THz-field-induced nonequilibrium\nspin-polarized currents; and subsequent multi-picosecond dynamics, possibly\nindicative of a change in the magnetic state of the superlattice due to the\ntransfer of spin angular momentum to the lattice. Our findings shed light on\nthe intricate interplay of electronic and magnetic phenomena in this strongly\ncorrelated material system, suggesting a promising avenue for efficient control\nof two-dimensional ferromagnetic states at oxide interfaces using ultrafast\nelectric-field pulses.",
        "positive": "Revealing the Superior Electrocatalytic Performance of 2D Monolayer\n  WSe$_2$ Transition Metal Dichalcogenide for Efficient H$_2$ Evolution\n  Reaction: H$_2$ evolution reaction (HER) requires an electrocatalyst to reduce the\nreaction barriers for the efficient production of H$_2$. Platinum-group metal\n(PGM) elements such as Pt, Pd, etc. and their derivatives show excellent\nelectrocatalytic activity for HER. The high cost and lack of availability of\nPGM elements bring constraints over their wide commercial applications, so\ndiscovering noble metal-free electrocatalysts with lower possible reaction\nbarriers is paramount important. Two-Dimensional Transition Metal\nDichalcogenides (2D TMDs) have emerged as a pinnacle group of materials for\nmany potential applications, including HER. In this work, we have\ncomputationally designed a pristine 2D monolayer tungsten diselenide (WSe$_2$)\nTMD using the first principle-based hybrid Density Functional Theory (DFT) to\ninvestigate its structural, electronic properties and the electrocatalytic\nperformance for HER. The possible Volmer-Heyrovsky and Volmer-Tafel reaction\nmechanisms for HER at the W-edge of the active site of WSe$_2$ were studied by\nusing a non-periodic finite molecular cluster model W$_{10}$Se$_{21}$. Our\nstudy shows that the pristine 2D monolayer WSe$_2$ follows either the\nVolmer-Heyrovsky or the Volmer-Tafel reaction mechanisms with a single-digit\nlow reaction barrier about 6.11, 8.41 and 6.61 kcal/mol during the solvent\nphase calculations of H-migration, Heyrovsky and Tafel transition (TS) states,\nrespectively. The lower reaction barriers, high turnover frequency (TOF) ~ 4.24\nx $10^6$ sec$^{-1}$ and 8.86 x $10^7$ sec$^{-1}$ during the Heyrovsky and Tafel\nreaction steps and the low Tafel slope 29.58 mV.dec$^{-1}$ confirm that the\npristine 2D monolayer WSe$_2$ might be a promising alternative to PGM based\nelectrocatalyst."
    },
    {
        "anchor": "Atomic-scale studies of Fe3O4(001) and TiO2(110) surfaces following\n  immersion in CO2-acidified water: Difficulties associated with the integration of liquids into a UHV\nenvironment make surface-science style studies of mineral dissolution\nparticularly challenging. Recently, we developed a novel experimental setup for\nthe UHV-compatible dosing of ultrapure liquid water, and studied its\ninteraction with TiO2 and Fe3O4 surfaces. Here, we describe a simple approach\nto vary the pH through the partial pressure of CO2 (pCO2) in the surrounding\nvacuum chamber, and use this to study how these surfaces react to an acidic\nsolution. The TiO2(110) surface is unaffected by the acidic solution, except\nfor a small amount of carbonaceous contamination. The Fe3O4(001)-(rt2 x rt2)R45\nsurface begins to dissolve at a pH 4.0-3.9 (pCO2 = 0.8-1 bar) and, although it\nis significantly roughened, the atomic-scale structure of the Fe3O4(001)\nsurface layer remains visible in scanning tunneling microscopy (STM) images.\nX-ray photoelectron spectroscopy (XPS) reveals that the surface is chemically\nreduced, and contains a significant accumulation of bicarbonate (HCO3-)\nspecies. These observations are consistent with Fe(II) being extracted by\nbicarbonate ions, leading to dissolved iron bicarbonate complexes (Fe(HCO3)2),\nwhich precipitate onto the surface when the water evaporates.",
        "positive": "Enhanced power factor and reduced Lorenz number in the Wiedemann--Franz\n  law due to pudding mold type band structures: We study the relationship between the shape of the electronic band structure\nand the thermoelectric properties. In order to study the band shape dependence\nof the thermoelectric properties generally, we first adopt models with band\nstructures having the dispersion $E({\\bf k}) \\sim |{\\bf k}|^n$ with $n = 2, 4$\nand 6. We consider one, two- and three dimensional systems, and calculate the\nthermoelectric properties using the Boltzmann equation approach within the\nconstant quasi-particle lifetime approximation. $n = 2$ corresponds to the\nusual parabolic band structure, while the band shape for $n = 4, 6$ has a flat\nportion at the band edge, so that the density of states diverges at the bottom\nof the band. We call this kind of band structure the \"pudding mold type band\".\n$n \\ge 4$ belong to the pudding mold type band, but since the density of states\ndiverges even for $n= 2$ in one dimensional system, this is also categorized as\nthe pudding mold type. Due to the large density of states and the rapid change\nof the group velocity around the band edge, the spectral conductivity of the\npudding mold type band structures becomes larger than that of the usual\nparabolic band structures. It is found that the pudding mold type band has a\ncoexistence of large Seebeck coefficient and large electric conductivity, and\nsmall Lorenz number in the Wiedemann--Franz law due to the specific band shape.\nWe also find that the low dimensionality of the band structure can contribute\nto large electronic conductivity and hence a small Lorenz number. We conclude\nthat the pudding mold type band, especially in low dimensional systems, can\nenhance not only the power factor but also the dimensionless figure of merit\ndue to stronger violation of the Wiedemann--Franz law."
    },
    {
        "anchor": "Water Oxidation Chemistry of Oxynitrides and Oxides: Comparing NaTaO$_3$\n  and SrTaO$_2$N: The oxygen evolution reaction (OER) plays an important role in evaluating a\nphotocatalyst and to understand its surface chemistry. In this work we present\na comparative study of the OER on the oxide NaTaO$_3$ (113) surface and the\noxynitride SrTaO$_2$N (001) surface. Oxynitrides are highly promising\nphotocatalysts due to their smaller band gap and resulting better visible light\nabsorption compared to oxides but our knowledge about their surface structure\nand chemistry is still very limited. With the goal to compare the surface\nchemistry of oxides and oxynitrides, we perform density functional theory\ncalculations to obtain the free energy changes associated with the OER reaction\nsteps. For the OER at the Ta site of the clean surfaces, our results predict\nthe rate-limiting step for both materials to be the formation of the *OOH\nintermediate, with a larger overpotential for the oxide than the oxynitride\n(1.30 V vs 1.01 V). The Na site is found to be more active than the Ta site on\nthe oxide surface with an OER overpotential of 0.88 V, whereas the OER at the\nSr site on the oxynitride has an overpotential of 1.14 V. For the A sites,\ncontrary to the Ta site, the deprotonation of *OH was found to be the\nrate-limiting step. Computed Pourbaix diagrams show that at relevant\n(photo)electrochemical conditions all surfaces are covered with oxygen\nadsorbates. Oxygen adsorbates at A (Na, Sr) sites are however found to couple\nand desorb as O$_2$, leaving these sites empty under typical operating\nconditions. Following this desorption, we find the OER to proceed by the\nconventional *OOH mechanism on the SrO termination of the oxynitride but by a\ndirect coupling of neighbouring *O at Na sites on the oxide surface. This\ncoupling mechanism on the oxide has the smallest overpotential of 0.79 V\ncompared to 0.88 V for the oxynitride, implying that the oxide is a better OER\ncatalyst.",
        "positive": "Carbosilicene and germasilicene: Two 2D materials with excellent\n  structural, electronic and optical properties: Using first principle calculations, we study the structural, optical and\nelectronic properties of two-dimensional silicene-like structures of CSi7\n(carbosilicene) and GeSi7 (germasilicene) monolayers. We show that both CSi7\nand GeSi7 monolayers have different buckling that promises a new way to control\nthe buckling in silicene-like structures. Carbon impurity decreases the\nsilicene buckling, whereas germanium impurity increases it. The CSi7 has\nsemiconducting properties with 0.25 eV indirect band gap, but GeSi7 is a\nsemimetal. Also, under uniaxial tensile strain, the semiconducting properties\nof CSi7 convert to metallic properties which shows that CSi7 can be used in\nstraintronic devices such as strain sensor and strain switch. There is no\nimportant response for GeSi7 under strain. The GeSi7 has higher dielectric\nconstant relative to CSi7, silicene and graphene and it can be used as a\n2D-material in high performance capacitors. Calculation of cohesive and\nformation energies show that CSi7 is more stable than GeSi7. Furthermore, we\ninvestigate the optical properties of these new materials and we show that CSi7\nand GeSi7 can significantly increase the light absorption of silicene. The\nobtained results can pave a new route for tuning the electronic and optical\nproperties of silicene like structures for different applications in\nnanoelectronic devices."
    },
    {
        "anchor": "Equations of state of magnesium perovskite and postperovskite:\n  diagnostics from ab initio simulations: The isothermal compression of magnesium perovskite and postperovskite is\nexamined through the F-f plot and the diagnostic plot of Vinet universal model\ntheoretically from the ab initio quantum-mechanical calculations at the hybrid\nHartree-Fock / Density Functional Theory level. A purely numerical approach,\nfirst time applied in this paper, shows that the discrepancies largely observed\nbetween studies on the perovskite and criticized in geophysical applications\nare due to the inadequate choice of the Birch-Murnaghan equation of state;\nmeanwhile the Vinet model is found utterly appropriate for the mineral and\ninfers consistent estimations of the bulk modulus and its pressure derivative.\nThe diagnostics of the postperovskite suggest similar conclusions.",
        "positive": "Upper bound of a band complex: Band structure for a crystal generally consists of connected components in\nenergy-momentum space, known as band complexes. Here, we explore a fundamental\naspect regarding the maximal number of bands that can be accommodated in a\nsingle band complex. We show that in principle a band complex can have no\nfinite upper bound for certain space groups. It means infinitely many bands can\nentangle together, forming a connected pattern stable against\nsymmetry-preserving perturbations. This is demonstrated by our developed\ninductive construction procedure, through which a given band complex can always\nbe grown into a larger one by gluing a basic building block to it. As a\nby-product, we demonstrate the existence of arbitrarily large accordion type\nband structures containing $N_C=4n$ bands, with $n\\in\\mathbb{N}$."
    },
    {
        "anchor": "High-Resolution In-situ Synchrotron X-ray Studies of Inorganic\n  Perovskite CsPbBr$_3$: New Symmetry Assignments and Structural Phase\n  Transitions: Perovskite photovoltaic ABX$_3$ systems are being studied due to their high\nenergy-conversion efficiencies with current emphasis placed on pure inorganic\nsystems. In this work, synchrotron single-crystal diffraction measurements\ncombined with second harmonic generation measurements reveal the absence of\ninversion symmetry below room temperature in CsPbBr$_3$. Local structural\nanalysis by pair distribution function and X-ray absorption fine structure\nmethods are performed to ascertain the local ordering, atomic pair\ncorrelations, and phase evolution in a broad range of temperatures. The\ncurrently accepted space group assignments for CsPbBr$_3$ are found to be\nincorrect in a manner that profoundly impacts physical properties. New\nassignments are obtained for the bulk structure: $Im$$\\bar{3}$ (above $\\sim$\n410 K), $P$2$_1$/$m$ (between $\\sim$ 300 K and $\\sim$ 410 K), and the polar\ngroup $Pm$ (below $\\sim$ 300 K), respectively. The newly observed structural\ndistortions exist in the bulk structure consistent with the expectation of\nprevious photoluminescence and Raman measurements. High-pressure measurements\nreveal multiple low-pressure phases, one of which exists as a metastable phase\nat ambient pressure. This work should help guide research in the perovskite\nphotovoltaic community to better control the structure under operational\nconditions and further improve transport and optical properties.",
        "positive": "Intrinsic ferroelectric properties of strained tetragonal PbZr0.2Ti0.8O3\n  obtained on layer-by-layer grown, defect-free single crystalline films: PbZrxTi1-xO3 (PZT) is one of the technologically most important ferroelectric\nmaterials. Bulk single-domain single crystals of PZT have never been\nsynthesized for a significant compositional range across the solid-solution\nphase diagram. This leaves the fundamental properties of PZT under debate.\nSynthesis of defect-free single crystalline films enables us to unambiguously\ndetermine the intrinsic quantities that describe ferroelectric materials, such\nas spontaneous polarization and dielectric constant. Defect-free single\ncrystalline, strained PbZr0.2Ti0.8O3 thin films were grown by pulsed-laser\ndeposition (PLD) onto vicinal SrTiO3 (001) single crystal substrates. Single\ncrystalline SrRuO3 films fabricated by PLD were employed as bottom electrode.\nThe PZT films have square shape hysteresis loops and remnant polarization\nvalues of up to Pr= 110 micro C/cm2, which is considerably higher than the\ntheoretical value predicted for (unstrained) bulk single crystalline PZT of the\ninvestigated composition. The films have a dielectric constant eps33= 90 and a\npiezoelectric coefficient d33= 50 pm/V."
    },
    {
        "anchor": "Electrical contacts to nanotubes and nanowires: why size matters: Metal-semiconductor contacts play a key role in electronics. Here we show\nthat for quasi-one-dimensional structures such as nanotubes and nanowires, side\ncontact with the metal only leads to weak band re-alignement, in contrast to\nbulk metal-semiconductor contacts. Schottky barriers are much reduced compared\nwith the bulk limit, and should facilitate the formation of good contacts.\nHowever, the conventional strategy of heavily doping the semiconductor to\nobtain ohmic contacts breaks down as the nanowire diameter is reduced. The\nissue of Fermi level pinning is also discussed, and it is demonstrated that the\nunique density of states of quasi-one-dimensional structures makes them less\nsensitive to this effect. Our results agree with recent experimental work, and\nshould apply to a broad range of quasi-one-dimensional materials.",
        "positive": "Unconventional polarization switching mechanism in (Hf, Zr)O2\n  ferroelectrics: HfO$_{2}$-based ferroelectric thin films are promising for their application\nin ferroelectric devices. Predicting the ultimate magnitude of polarization and\nunderstanding its switching mechanism are critical to realize the optimal\nperformance of these devices. Here, a generalized solid-state variable cell\nnudged elastic band (VCNEB) method is employed to predict the switching pathway\nassociated with domain-wall motion in (Hf, Zr)O$_{2}$ ferroelectrics. It is\nfound that the polarization reversal pathway, where three-fold coordinated O\natoms pass across the nominal unit-cell boundaries defined by the Hf/Zr atomic\nplanes, is energetically more favorable than the conventional pathway where the\nO atoms do not pass through these planes. This finding implies that the\npolarization orientation in the orthorhombic Pca2$_{1}$ phase of HfO$_{2}$ nd\nits derivatives is opposite to that normally assumed, predicts the spontaneous\npolarization magnitude of about 70 ${\\mu}$C/cm$^{2}$ that is nearly 50% larger\nthan the commonly accepted value, signifies a positive intrinsic longitudinal\npiezoelectric coefficient, and suggests growth of ferroelectric domains, in\nresponse to an applied electric field, structurally reversed to those usually\nanticipated. These results provide important insights into the understanding of\nferroelectricity in HfO$_{2}$-based ferroelectrics."
    },
    {
        "anchor": "Pressure effect on the order-disorder transformation in L1$_0$ FeNi: The ordered phase of the FeNi system is known to have promising magnetic\nproperties as a rare-earth-free permanent magnet. Understanding the parameter\nspace that controls the order-disorder transformation is important to find\ngrowth conditions that stabilize the $L1_0$ phase. Magnetic properties and\nchemical order-disorder transformation of FeNi are investigated as a function\nof lattice expansion using first-principles theory. Thermodynamic and magnetic\ncalculations are performed using long-range order parameters, which is used to\nfind the ordering temperature. Negative pressure promotes ordering and thus\nsynthetic routes involving an increase in volume is expected to expand the\nstability field of the $L1_0$ phase.",
        "positive": "Nearly Free Electron States in MXenes: Using a set of first-principles calculations, we studied the electronic\nstructures of two-dimensional transition metal carbides and nitrides, so called\nMXenes, functionalized with F, O, and OH. Our projected band structures and\nelectron localization function analyses reveal the existence of nearly free\nelectron (NFE) states in variety of MXenes. The NFE states are spatially\nlocated just outside the atomic structure of MXenes and are extended parallel\nto the surfaces. Moreover, we found that the OH-terminated MXenes offer the NFE\nstates energetically close to the Fermi level. In particular, the NFE states in\nsome of the OH-terminated MXenes, such as Ti2C(OH)2, Zr2C(OH)2, Zr2N(OH)2,\nHf2C(OH)2, Hf2N(OH)2, Nb2C(OH)2, and Ta2C(OH)2, are partially occupied. This is\nin remarkable contrast to graphene, graphane, and MoS2, in which their NFE\nstates are located far above the Fermi level and thus they are unoccupied. As a\nprototype of such systems, we investigated the electron transport properties of\nHf2C(OH)2 and found that the NFE states in Hf2C(OH)2 provide almost perfect\ntransmission channels without nuclear scattering for electron transport. Our\nresults indicate that these systems might find applications in nanoelectronic\ndevices. Our findings provide new insights into the unique electronic band\nstructures of MXenes."
    },
    {
        "anchor": "Pressure and strain effects on the optical properties of K4 phosphorus: An investigation of the mechanical, electronic, and optical properties of the\nrecently reported material K4 phosphorus was made in this work. The K4\nphosphorus has been proved to be mechanically and dynamically stable up to 7\nGPa under hydrostatic pressure. We compared the elastic anisotropy, average\nacoustic velocity and Debye temperature of K4 phosphorus at 0 and 7 GPa. The\nideal tensile at large strains of K4 phosphorus was also examined, with the\nresults showing that it would cleave under the tensile strength of 8.5 GPa with\nthe strain of 0.3. In addition, the effect of tensile strain and pressure on\noptical properties and band gap were studied.",
        "positive": "Intragranular Strain Estimation in Far-Field Scanning X-ray Diffraction\n  using a Gaussian Processes: A new method for estimation of intragranular strain fields in polycrystalline\nmaterials based on scanning three-dimensional X-ray diffraction data\n(scanning-3DXRD) is presented and evaluated. Given an apriori known anisotropic\ncompliance, the regression method enforces the balance of linear and angular\nmomentum in the linear elastic strain field reconstruction. By using a Gaussian\nProcess (GP), the presented method can yield a spatial estimate of the\nuncertainty of the reconstructed strain field. Furthermore, constraints on\nspatial smoothness can be optimised with respect to measurements through\nhyperparameter estimation. These three features address weaknesses discussed\nfor previously existing scanning-3DXRD reconstruction methods and, thus, offers\na more robust strain field estimation. The method is twofold validated; firstly\nby reconstruction from synthetic diffraction data and, secondly, by\nreconstruction of previously studied tin (Sn) grain embedded in a\npolycrystalline specimen. Comparison against reconstructions achieved by a\nrecently proposed algebraic inversion technique is also presented. It is found\nthat the GP regression consistently produces reconstructions with lower root\nmean squared errors, mean absolute errors and maximum absolute errors across\nall six components of strain."
    },
    {
        "anchor": "Irreversible thermodynamics of creep in crystalline solids: We develop an irreversible thermodynamics framework for the description of\ncreep deformation in crystalline solids by mechanisms that involve vacancy\ndiffusion and lattice site generation and annihilation. The material undergoing\nthe creep deformation is treated as a non-hydrostatically stressed\nmulti-component solid medium with non-conserved lattice sites and\ninhomogeneities handled by employing gradient thermodynamics. Phase fields\ndescribe microstructure evolution which gives rise to redistribution of vacancy\nsinks and sources in the material during the creep process. We derive a general\nexpression for the entropy production rate and use it to identify of the\nrelevant fluxes and driving forces and to formulate phenomenological relations\namong them taking into account symmetry properties of the material. As a simple\napplication, we analyze a one-dimensional model of a bicrystal in which the\ngrain boundary acts as a sink and source of vacancies. The kinetic equations of\nthe model describe a creep deformation process accompanied by grain boundary\nmigration and relative rigid translations of the grains. They also demonstrate\nthe effect of grain boundary migration induced by a vacancy concentration\ngradient across the boundary.",
        "positive": "Establishing Coherent Momentum-Space Electronic States in Locally\n  Ordered Materials: In our understanding of solids, the formation of highly spatially coherent\nelectronic states, fundamental to command the quantum behavior of materials,\nrelies on the existence of discrete translational symmetry of the crystalline\nlattice. In contrast, in the absence of long-range order, as in the case of\nnon-crystalline materials, the electronic states are localized and electronic\ncoherence does not develop. This brings forward the fundamental question\nwhether long range order is necessary condition to establish coherence and\nstructured momentum-dependent electronic state, and how to characterize it in\nthe presence of short-range order. Here we study Bi$_2$Se$_3$, a material that\nexists in its crystalline form with long range order, in amorphous form, with\nshort and medium range order, and in its nanocrystalline form, with reduced\nshort range order. By using angle resolved photoemission spectroscopy to\ndirectly access the electronic states in a momentum resolved manner, we reveal\nthat, even in the absence of long-range order, a well-defined real-space length\nscale is sufficient to produce dispersive band structures. Moreover, we observe\nfor the first time a repeated Fermi surface structure of duplicated annuli,\nreminiscent of Brillouin zone-like repetitions. These results, together with\nour simulations using amorphous Hamiltonians, reveal that the typical momentum\nscale where coherence occurs is the inverse average nearest-neighbor distance,\nthe direct fingerprint of the local order of the underlying atomic structure.\nThese results, not only lead the way to a new understanding of electronic\ncoherence in solids, but also open the way to the realization of novel\nmomentum-dependent quantum phenomena such as momentum pairing and spin-orbit\ncoupling, in a much broader class of materials than the currently studied ones,\nlacking long range crystalline translational symmetry."
    },
    {
        "anchor": "RadonPy: Automated Physical Property Calculation using All-atom\n  Classical Molecular Dynamics Simulations for Polymer Informatics: The rapid growth of data-driven materials research has made it necessary to\ndevelop systematically designed, open databases of material properties.\nHowever, there are few open databases for polymeric materials compared to other\nmaterial systems such as inorganic crystals. To this end, we developed RadonPy,\nthe world-first open-source Python library for fully automated all-atom\nclassical molecular dynamics (MD) simulations. For a given polymer repeating\nunit, the entire process of molecular modeling, equilibrium and nonequilibrium\nMD calculations, and property calculations can be conducted fully\nautomatically. In this study, 15 different properties, including the thermal\nconductivity, density, specific heat capacity, thermal expansion coefficients,\nand refractive index, were calculated for more than 1,000 unique amorphous\npolymers. The calculated properties were compared and validated systematically\nwith experimental values from PoLyInfo. During the high-throughput data\nproduction, eight amorphous polymers with extremely high thermal\nconductivities, exceeding 0.4 W/mK, were identified, including six polymers\nwith unreported thermal conductivities. These polymers were found to have a\nhigh density of hydrogen bonding units or rigid backbones. A decomposition\nanalysis of the heat conduction, which is implemented in RadonPy, revealed the\nunderlying mechanisms that yield a high thermal conductivity of the amorphous\npolymers: heat transfer via hydrogen bonds and dipole-dipole interactions\nbetween the polymer chains with their hydrogen bonding units or via the\ncovalent bonds of the polymer backbone with high rigidity. The creation of\nmassive amounts of computational property data using RadonPy will facilitate\nthe development of polymer informatics, similar to how the emergence of the\nfirst-principles computational database for inorganic crystals had\nsignificantly advanced materials informatics.",
        "positive": "Atomic-level description of thermal fluctuations in inorganic lead\n  halide perovskites: The potential of lead-halide perovskites for realistic applications is\ncurrently hindered by their limited long-term stability under functional\nactivation. While the role of lattice flexibility in the thermal response of\nperovskites has become increasingly evident, the description of\nthermally-induced distortions is still unclear. In this work, we provide a\nunified picture of thermal activation in CsPbBr3 across length scales, showing\nthat lattice symmetry does not increase at high temperatures. We combine\ntemperature-dependent XRD, Br K-edge XANES, ab initio MD simulations, and\ncalculations of the XANES spectra by first-principles, accounting for both\nthermal fluctuations and core hole final state effects. We find that the\noctahedral tilting of the Pb-Br inorganic framework statistically adopts\nmultiple local configurations over time - in the short-range. In turn, the\nstochastic nature of the local thermal fluctuations uplifts the longer-range\nperiodic octahedral tilting characterizing the low temperature structure, with\nthe statistical mean of the local configurations resulting in a cubic-like\ntime-averaged lattice. These observations can be rationalized in terms of\ndisplacive thermal phase transitions through the soft mode model, in which the\nphonon anharmonicity of the flexible inorganic framework causes the excess free\nenergy surface to change as a function of temperature. Our work demonstrates\nthat the effect of thermal dynamics on the XANES spectra can be effectively\ndescribed for largely anharmonic systems, provided ab initio MD simulations are\nperformed to determine the dynamically fluctuating structures, and core hole\nfinal state effects are included in order to retrieve an accurate XANES line\nshape. Moreover, it shows that the soft mode model, previously invoked to\ndescribe displacive thermal phase transitions in oxide perovskites, carries a\nmore general validity."
    },
    {
        "anchor": "Magnetism and magnetic asphericity in NiFe alloys: We here study magnetic properties of Ni$_{x}$Fe$_{1-x}$ using Augmented space\nrecursion technique coupled with tight-binding linearized muffin tin orbital\nmethod. Also the spectral properties of this alloy has been studied here.",
        "positive": "Recent Advances in Thermoelectric Performance of Half-Heusler Compounds: Half-Heusler phases (space group F43m, C1b) have recently captured much\nattention as promising thermoelectric materials for heat-to-electric power\nconversion in the mid-to-high temperature range. The most studied ones are the\nRNiSn-type half-Heusler compounds, where R represents refractory metals Hf, Zr,\nand Ti. These compounds have shown a high-power factor and high-power density,\nas well as good material stability and scalability. Due to their high thermal\nconductivity, however, the dimensionless figure of merit (zT) of these\nmaterials has stagnated near 1 for a long time. Since 2013, the verifiable ZT\nof half-Heusler compounds has risen from 1 to near 1.5 for both n- and p-type\ncompounds in the temperature range of 500 to 900 degrees C. In this brief\nreview, we summarize recent advances as well as approaches in achieving the\nhigh ZT reported. In particular, we discuss the less-exploited strain-relief\neffect and dopant resonant state effect studied by the author and his\ncollaborators in more detail. Finally, we point out directions for further\ndevelopment.\n  Keywords: half-Heusler compounds; figure of merit; power density; lattice\ndisorder; dopant resonant states"
    },
    {
        "anchor": "Induced magnetic moment in graphene with a nonmagnetic impurity: We consider a two-dimensional crystalline monolayer of carbon atoms with a\nsingle non-magnetic impurity. Using the Weyl Hamiltonian to describe electronic\nenergy spectrum near the Dirac points, we calculate the wave function and\nenergy of impurity states, as well as the induced magnetic moment associated\nwith polarization of the electron system. We present a phase diagram of the\nlocalized magnetic state as a function of the chemical potential $\\mu $ and\ncoupling constant $g_c$.",
        "positive": "Ab initio thermodynamics of intrinsic oxygen vacancies in ceria: Nonstoichiometric ceria(CeO$_{2-\\delta}$) is a candidate reaction medium to\nfacilitate two step water splitting cycles and generate hydrogen. Improving\nupon its thermodynamic suitability through doping requires an understanding of\nits vacancy thermodynamics. Using density functional theory(DFT) calculations\nand a cluster expansion based Monte Carlo simulations, we have studied the high\ntemperature thermodynamics of intrinsic oxygen vacancies in ceria. The DFT+$U$\napproach was used to get the ground state energies of various vacancy\nconfigurations in ceria, which were subsequently fit to a cluster expansion\nHamiltonian to efficiently model the configurational dependence of energy. The\neffect of lattice vibrations was incorporated through a temperature dependent\ncluster expansion. Lattice Monte Carlo simulations using the cluster expansion\nHamiltonian were able to detect the miscibility gap in the phase diagram of\nceria. The inclusion of vibrational and electronic entropy effects made the\nagreement with experiments quantitative. The deviation from an ideal solution\nmodel was quantified by calculating as a function of nonstoichiometry, a) the\nsolid state entropy from Monte Carlo simulations and b) Warren-Cowley short\nrange order parameters of various pair clusters."
    },
    {
        "anchor": "Control of Ionic Mobility via Charge Size Asymmetry in Random Ionomers: Solid polymer electrolytes are considered a promising alternative to\ntraditional liquid electrolytes in energy storage applications because of their\ngood mechanical properties, and excellent thermal and chemical stability. A\ngap, however, still exists in understanding ion transport mechanisms and\nimproving ion transport in solid polymer electrolytes. Therefore, it is crucial\nto bridge composition--structure and structure--property relationships. Here we\ndemonstrate that size asymmetry, $\\lambda$, represented by the ratio of\ncounterion to charged monomer size, plays a key role in both the nanostructure\nand in the ionic dynamics. More specifically, when the nanostructure is\nmodified by the external electric field such that the mobility cannot be\ndescribed by linear response theory, two situations arise. The ionic mobility\nincreases as $\\lambda$ decreases (small counterions) in the weak electrostatics\n(high dielectric constant) regime. Whereas in systems with strong electrostatic\ninteractions, ionomers with higher size symmetry ($\\lambda \\approx 1$) display\nhigher ionic mobility. Moreover, ion transport is found to be dominated by the\nhopping of the ions and not by moving ionic clusters (also known as\n\"vehicular'' charge transport). These results serve as a guide for designing\nion-containing polymers for ion transport related applications.",
        "positive": "Enhanced performance of MoS$_2$/SiO$_2$ field-effect transistors by\n  hexamethyldisilazane (HMDS) encapsulation: Scalable methods for improving the performance and stability of a\nfield-effect transistor (FET) based on two-dimensional materials are crucial\nfor its real applications. A scalable method of encapsulating the exfoliated\nMoS$ _{2} $ on SiO$ _{2} $/Si substrate by hexamethyldisilazane (HMDS) is\nexplored here for reducing the influence of interface traps and ambient\ncontaminants. This leads to twenty-five times reduction in trap density, three\ntimes decrease in subthreshold swing, three times increase in the peak\nfield-effect mobility and a drastic reduction in hysteresis. This performance\nremains nearly the same after several weeks of ambient exposure of the device.\nThis is attributed to the superhydrophobic nature of HMDS and the SiO$_2$\nsurface hydrophobization by the formation of covalent bonds between the methyl\ngroups of HMDS and silanol groups of SiO$_{2}$."
    },
    {
        "anchor": "Thin Film growth of Solid State materials: Magnetron sputtering has also been used to deposit thin films of some\nmaterials and it has significant technological importance. A modeling on\ndeposition of epitaxial thin films of Yttrium Stabilized Zirconia (YSZ) was\ndone the diffusion of adatom on the surface were studies. There exists a strong\ninteraction of ions formed in the plasma during the sputtering process. Cu thin\nfilms were deposited on Si. Nanocomposite thin film of SiCN showed dendritic\ngrowth.",
        "positive": "Empirical correlation between the interfacial Dzyaloshinskii Moriya\n  interaction and work function in metallic magnetic trilayers: The Dzyaloshinskii Moriya interaction (DMI) generates intriguing chiral\nmagnetic objects such as magnetic skyrmions and chiral domain walls that can be\nused as building blocks in emerging magnetic nanodevices. To achieve better\nstability and functionality of these chiral objects, it is essential to achieve\na larger DMI. In this paper, we report an experimental observation that in\nmagnetic trilayer films, the DMI strength is mainly determined by the work\nfunctions of the nonmagnetic layers interfaced with the magnetic layer. The\nclear correlation with the intrinsic material parameters provides a guideline\nfor material selection to engineer the DMI strength."
    },
    {
        "anchor": "Effective Phonon Dispersion and Low field transport in AlxGa1-xN alloys\n  using supercells: An ab-initio approach: To investigate the transport properties in random alloys, it is important to\nmodel the alloy disorder using supercells. Though traditional methods like\nVirtual Crystal Approximation (VCA) are computationally efficient, the local\ndisorder in the system is not accurately captured as artificial translational\nsymmetry is imposed on the system. However, in the case of supercells, the\nerror introduced by self-image interaction between the impurities is reduced\nand translational symmetry is explicitly imposed over larger length scales. In\nthis work, we have investigated the Effective Phonon Dispersion (EPD) and\ntransport properties, from first principle calculations using supercells in\nAlxGa1-xN alloy systems. Using our in-house developed code, the EPD of AlGaN is\nobtained and the individual modes are identified. Next, we discuss our in-house\ndeveloped method to calculate low-field transport properties in supercells.\nFirst to validate our methods we have solved the Boltzmann Transport Equation\nusing Rode method to compare the phonon limited mobility in the 4 atom GaN\nprimitive cell and 12 atom GaN supercell. Using the same technique, we have\ninvestigated the low field transport in random AlxGa1-xN alloy systems. Our\ncalculations show that along with alloy scattering, electron-phonon scattering\nmay also play an important role at room temperature and high-temperature device\noperation. This technique opens up the path for calculating phonon-limited\ntransport properties in random alloy systems.",
        "positive": "Theory of superfast fronts of impact ionization in semiconductor\n  structures: We present an analytical theory for impact ionization fronts in reversely\nbiased p^{+}-n-n^{+} structures. The front propagates into a depleted n base\nwith a velocity that exceeds the saturated drift velocity. The front passage\ngenerates a dense electron-hole plasma and in this way switches the structure\nfrom low to high conductivity. For a planar front we determine the\nconcentration of the generated plasma, the maximum electric field, the front\nwidth and the voltage over the n base as functions of front velocity and doping\nof the n base. Theory takes into account that drift velocities and impact\nionization coefficients differ between electrons and holes, and it makes\nquantitative predictions for any semiconductor material possible."
    },
    {
        "anchor": "SAXS/WAXS/DSC Study of Temperature Evolution in Nanopolymer Electrolyte: Electrolytes as nanostructured materials are very attractive for batteries or\nother types of electronic devices. (PEO)8ZnCl2 polymer electrolytes and\nnanocomposites (PEO)8ZnCl2/TiO2 were prepared from PEO and ZnCl2 and with\naddition of TiO2 nanograins. The influence of TiO2 nanograins was studied by\nsmall-angle X-ray scattering (SAXS) simultaneously recorded with wide-angle\nX-ray scattering (WAXS) and differential scanning calorimetry (DSC) at the\nsynchrotron ELETTRA. It was shown by previous impedance spectroscopy (IS) that\nthe room temperature conductivity of nanocomposite polymer electrolyte\nincreased more than two times above 65oC, relative to pure composites of PEO\nand salts. The SAXS/DSC measurements yielded insight into the\ntemperature-dependent changes of the grains of the electrolyte as well as to\ndifferences due to different heating and cooling rates. The crystal structure\nand temperatures of melting and crystallization of the nanosize grains was\nrevealed by the simultaneous WAXS measurements.",
        "positive": "Exciton band structure in two-dimensional materials: Low-dimensional materials differ from their bulk counterpart in many\nrespects. In particular, the screening of the Coulomb interaction is strongly\nreduced, which can have important consequences such as the significant increase\nof exciton binding energies. In bulk materials the binding energy is used as an\nindicator in optical spectra to distinguish different kinds of excitons, but\nthis is not possible in low-dimensional materials, where the binding energy is\nlarge and comparable in size for excitons of very different localization. Here\nwe demonstrate that the exciton band structure, which can be accessed\nexperimentally, instead provides a powerful way to identify the exciton\ncharacter. By comparing the ab initio solution of the many-body Bethe-Salpeter\nequation for graphane and single-layer hexagonal BN, we draw a general picture\nof the exciton dispersion in two-dimensional materials, highlighting the\ndifferent role played by the exchange electron-hole interaction and by the\nelectronic band structure. Our interpretation is substantiated by a prediction\nfor phosphorene."
    },
    {
        "anchor": "Ab initio study of the vibrational properties of crystalline TeO2: The\n  alpha, beta, and gamma phases: Based on density functional perturbation theory, we have studied the\nvibrational properties of three crystalline phases of tellurium dioxide:\nparatellurite alpha-TeO2, tellurite beta-TeO2, and the new phase gamma-TeO2,\nrecently identified experimentally. Calculated Raman and IR spectra are in good\nagreement with available experimental data. The vibrational spectra of alpha-\nand beta-TeO2 can be interpreted in terms of vibrations of TeO2 molecular\nunits.",
        "positive": "Effect of ZrH2 particles on the microstructure and mechanical properties\n  of IN718 manufactured by selective laser melting: The influence of Zr additions (in the form of ZrH2 particles) on the\nmicrostructure and mechanical properties of IN718 Ni-based superalloy\nmanufactured by selective laser melting was explored. Fully dense alloys could\nbe obtained by careful selection of the processing parameters. The addition of\nZrH2 did not modify the microstructure of the alloy but introduced a dispersion\nof Zr-rich globular particles of approximately 50 nm in diameter which\nincreased the strength of the as-printed material at ambient (23C) and high\ntemperature (550C). Heat treatments of solubilisation followed by aging led to\na fine dispersion of gamma\" precipitates that controlled the strength of the\nalloy, which was independent of the addition of Zr. Moreover, dynamic strain\nageing was found in the heat treated materials when deformed at 550C. Finally,\nthe strength of the IN718 deformed perpendicular to the building direction was\nhigher than that along the building direction, regardless of the heat treatment\nand temperature. Computational homogenization simulations showed that the\nanisotropy was associated with the strong texture."
    },
    {
        "anchor": "Current-Dependent Periodicities of Si(553)-Au: We investigate quasi one-dimensional atomic chains on Si(553)-Au with a\nscanning tunneling microscope (STM). The observed periodicity at the Si step\nedge can be altered by the STM and depends on the magnitude of the tunneling\ncurrent. In a recent report this reversible structural transition was\nattributed to transient doping with a characteristic time scale of a few\nmilliseconds. Here we explore the evolution of the STM topography as a function\nof the magnitude of the tunneling current for a wide temperature range. Based\non a decomposition of topographic line profiles and a detailed Fourier analysis\nwe conclude that all observed currentdependent STM topographies can be\nexplained by a time-averaged linear combination of two fluctuating step-edge\nstructures. These data also reveal the precise relative alignment of the\ncharacteristic STM features for both phases along the step edges. A simple\ndiagram is developed, presenting the relative contribution of these phases to\nthe STM topography as a function of tunneling current and temperature. Time-\nand current-dependent measurements of fluctuations in the tunneling current\nreveal two different transition regimes that are related to two specific\ncurrent injection locations within the surface unit cell. A method based on\nspatially resolved I(z)curves is presented that enables a quantitative analysis\nof contributing phases.",
        "positive": "First-principles study of magnetic states and the anomalous Hall\n  conductivity of $M$Nb$_3$S$_6$ ($M$=Co, Fe, Mn, and Ni): Inspired by the observation of the extremely large anomalous Hall effect in\nthe absence of applied magnetic fields or uniform magnetization in\nCoNb$_3$S$_6$ [Nature Comm. 9, 3280 (2018); Phys. Rev. Research 2, 023051\n(2020)], we perform a first-principles study of this and related compounds of\nthe $M$Nb$_3$S$_6$ type with different transition metal $M$ ions to determine\ntheir magnetic orders and the anomalous Hall conductivity (AHC). We find that\nnon-coplanar antiferromagnetic ordering is favored relative to collinear or\ncoplanar order in the case of $M$=Co, Fe and Ni, while ferromagnetic ordering\nis favored in MnNb$_3$S$_6$ at low temperatures. The AHC in these materials\nwith non-coplanar spin ordering can reach about $e^2/h$ per crystalline layer,\nwhile being negligible for coplanar and collinear cases. We also find that the\nAHC depends sensitively on doping and reaches a maximum for intermediate values\nof the local spin exchange potential between 0.3 and 0.8 eV. Our AHC results\nare consistent with the reported Hall measurements in CoNb$_3$S$_6$ and suggest\na possibility of similarly large anomalous Hall effects in related compounds."
    },
    {
        "anchor": "Native NIR-emitting single colour centres in CVD diamond: Single-photon sources are a fundamental element for developing quantum\ntechnologies, and sources based on colour centres in diamonds are among the\nmost promising candidates. The well-known NV centres are characterized by\nseveral limitations, thus few other defects have recently been considered. In\nthe present work, we characterize in detail native efficient single colour\ncentres emitting in the near infra-red in both standard IIa single-crystal and\nelectronic-grade polycrystalline commercial CVD diamond samples. In the former\ncase, a high-temperature annealing process in vacuum is necessary to induce the\nformation/activation of luminescent centres with good emission properties,\nwhile in the latter case the annealing process has marginal beneficial effects\non the number and performances of native centres in commercially available\nsamples. Although displaying significant variability in several photo physical\nproperties (emission wavelength, emission rate instabilities, saturation\nbehaviours), these centres generally display appealing photophysical properties\nfor applications as single photon sources: short lifetimes, high emission rates\nand strongly polarized light. The native centres are tentatively attributed to\nimpurities incorporated in the diamond crystal during the CVD growth of\nhigh-quality type IIa samples, and offer promising perspectives in\ndiamond-based photonics.",
        "positive": "Calibration of oscillation amplitude in Dynamic Scanning Force\n  Microscopy: A method to precisely calibrate the oscillation amplitude in Dynamic Scanning\nForce Microscopy is described. It is experimentally shown that a typical\nelectronics used to process the dynamic motion of the cantilever can be\nadjusted to transfer the thermal noise of the cantilever motion from its\nresonance frequency to a much lower frequency within the typical bandwidth of\nthe corresponding electronics. Therefore, the thermal noise measured in the\nin-phase (\"phase\") and out of phase (\"amplitude\") output of such an electronics\ncan be related to the thermal energy $kT$. If the force constant of the\ncantilever is known then the oscillation amplitude can be precisely calibrated\nfrom the thermal power measured in these signals. Based on this concept, two\nprocedures for the calibration of the oscillation amplitude are proposed. One\nis based on simple calculation of the Root Mean Square (RMS) measured at the\noutputs of the electronics used to process the dynamic motion of the\ncantilever, and the other one is based on analysis of the corresponding\nspectrum and the calculation of the quality factor, the resonance frequency and\nthe signal strength."
    },
    {
        "anchor": "Atomically sharp domain walls in an antiferromagnet: The interest in understanding scaling limits of magnetic textures such as\ndomain walls spans the entire field of magnetism from its relativistic quantum\nfundamentals to applications in information technologies. The traditional focus\nof the field on ferromagnets has recently started to shift towards\nantiferromagnets which offer a rich materials landscape and utility in\nultra-fast and neuromorphic devices insensitive to magnetic field\nperturbations. Here we report the observation that domain walls in an epitaxial\ncrystal of antiferromagnetic CuMnAs can be atomically sharp. We reveal this\nultimate domain wall scaling limit using differential phase contrast imaging\nwithin aberrationcorrected scanning transmission electron microscopy, which we\ncomplement by X-ray magnetic dichroism microscopy and ab initio calculations.\nWe highlight that the atomically sharp domain walls are outside the remits of\nestablished spin-Hamiltonian theories and can offer device functionalities\nunparalleled in ferromagnets.",
        "positive": "Traps and transport resistance: the next frontier for stable\n  state-of-the-art non-fullerene acceptor solar cells: Stability is one of the most important challenges facing organic solar cells\n(OSC) on their path to commercialization. In the high-performance material\nsystem PM6:Y6 studied here, investigate degradation mechanisms of inverted\nphotovoltaic devices. We have identified two distinct degradation pathways: one\nrequires presence of both illumination and oxygen and features a short-circuit\ncurrent reduction, the other one is induced thermally and marked by severe\nlosses of open-circuit voltage and fill factor. We focus our investigation on\nthe thermally accelerated degradation. Our findings show that bulk material\nproperties and interfaces remain remarkably stable, however, aging-induced\ndefect state formation in the active layer remains the primary cause of thermal\ndegradation. The increased trap density leads to higher non-radiative\nrecombination, which limits open-circuit voltage and lowers charge carrier\nmobility in the photoactive layer. Furthermore, we find the trap-induced\ntransport resistance to be the major reason for the drop in fill factor. Our\nresults suggest that device lifetimes could be significantly increased by\nmarginally suppressing trap formation, leading to a bright future for OSC."
    },
    {
        "anchor": "Electron transparent graphene windows for environmental scanning\n  electron microscopy in liquids and dense gases: Due to its ultrahigh electron transmissivity in a wide electron energy range,\nmolecular impermeability, high electrical conductivity and excellent mechanical\nstiffness the suspended graphene membranes appear to be a nearly ideal window\nmaterial for in situ (in vivo) environmental electron microscopy of nano- and\nmesoscopic objects (including bio-medical samples) immersed in liquids and/or\nin dense gaseous media. In this communication, taking advantage of little\nmodification of the graphene transfer protocol on to metallic and SiN\nsupporting orifices, the reusable environmental cells with exchangeable\ngraphene windows have been designed. Using colloidal gold nanoparticles (50 nm)\ndispersed in water as model objects for scanning electron microscopy in\nliquids, the different imaging conditions through graphene membrane have been\ntested. The limiting factors for electron microscopy in liquids such as\nelectron beam induced water radiolysis and damage of graphene membrane at high\nelectron doses were discussed.",
        "positive": "Lead-free Magnetic Double Perovskites for Photovoltaic and\n  Photocatalysis Applications: The magnetic spin degrees of freedom in magnetic materials serve as\nadditional capability to tune materials properties, thereby invoking\nmagneto-optical response. Herein, we report the magneto-optoelectronic\nproperties of a family of lead-free magnetic double perovskites Cs_{2}AgTX_{6}\n(T = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu; X=Cl, Br, I). This turns out to provide\nan extremely fertile series, giving rise to potential candidate materials for\nphotovoltaic(PV) applications. In conjunction with high absorption coefficient\nand high simulated power conversion efficiency for PV applications, few\ncompounds in this series exhibit novel magnetic character useful for spintronic\napplications. The interaction between magnetism and light can have far-reaching\nresults on the photovoltaic properties as a consequence of the shift in the\ndefect energy levels due to Zeeman effect. This subsequently affects the\nrecombination rate of minority carriers, and hence the photoconversion\nefficiency. Moreover, the distinct ferromagnetic and anti-ferromagnetic\nordering driven by hybridization and super-exchange mechanism can play a\nsignificant role to break the time-reversal and/or inversion symmetry. Such a\ncoalescence of magnetism and efficient optoelectronic response has the\npotential to trigger magnetic/spin anomalous photovoltaic (non-linear Optical)\neffect in this Cs$_{2}$AgTX$_{6}$ family. These insights can thus channelize\nthe advancement of lead-free double perovskites in magnetic/spin anomalous\nphotovoltaic field as well."
    },
    {
        "anchor": "Spin relaxation via exchange with donor impurity-bound electrons: At low temperatures, electrons in semiconductors are bound to shallow donor\nimpurity ions, neutralizing their charge in equilibrium. Inelastic scattering\nof other externally-injected conduction electrons accelerated by electric\nfields can excite transitions within the manifold of these localized states.\nPromotion of the bound electron into highly spin-orbit-mixed excited states\ndrives a strong spin relaxation of the conduction electrons via exchange\ninteractions, reminiscent of the Bir-Aronov-Pikus process where exchange occurs\nwith valence band hole states. Through low-temperature experiments with silicon\nspin transport devices and complementary theory, we reveal the consequences of\nthis previously unknown spin depolarization mechanism both below and above the\nimpact ionization threshold.",
        "positive": "Resonance Anomalous Surface X-ray Scattering: Resonance anomalous surface x-ray scattering (RASXS) technique was applied to\nelectrochemical interface studies. It was used to determine the chemical states\nof electrochemically formed anodic oxide monolayers on platinum surface. It is\nshown that RASXS exhibits strong polarization dependence when the surface is\nsignificantly modified. The polarization dependence is demonstrated for three\nexamples; anodic oxide formation, sulfate adsorption, and CO adsorption on\nplatinum surfaces. s- and p- polarization RASXS data were simulated with the\nlatest version of ab initio multiple scattering calculations (FEFF8.2).\nElementary theoretical considerations are also presented for the origin of the\npolarization dependence in RASXS."
    },
    {
        "anchor": "Evidence for In-Plane Tetragonal c-axis in Mn$_x$Ga$_{1-x}$ Thin Films\n  using Transmission Electron Microscopy: Tetragonal Mn$_x$Ga$_{1-x}$ (x=0.70, 0.75) thin films grown on SrTiO$_3$\nsubstrates at different temperatures and thicknesses exhibit perpendicular\nmagnetic anisotropy with coercive fields between 1-2 T. Transmission electron\nmicroscopy (TEM) and X-ray diffraction (XRD) reveal that 40nm samples grown at\n300-350$^{o}$C lead to polycrystalline films with the tetragonal c-axis\noriented primarily perpendicular to the film plane but with some fraction of\nthe sample exhibiting the c-axis in the film plane. This structure results in a\nsecondary magnetic component in the out of plane magnetization. Growth at\n300$^{o}$C with a reduced thickness or Mn concentration significantly decreases\nthe presence of the tetragonal c-axis in the film plane, thus improving the\nmagnetic properties. TEM is of critical importance in characterizing these\nmaterials, since conventional XRD cannot always identify the presence of\nadditional crystallographic orientations although they can still affect the\nmagnetic properties. Our study points to ways that the microstructure of these\nthin films can be controlled, which is critical for utilization of this\nmaterial in spintronic devices.",
        "positive": "Strong enhancement of Jc in binary and alloyed in-situ MgB2 wires by a\n  new approach: Cold high pressure densification: Cold high pressure densification (CHPD) is presented as a new way to\nsubstantially enhance the critical current density of in situ MgB2 wires at 4.2\nand 20 K at fields between 5 and 14 T. The results on two binary MgB2 wires and\nan alloyed wire with 10 wt.% B4C are presented The strongest enhancement was\nmeasured at 20K, where cold densification at 1.85 GPa on a binary Fe/MgB2 wire\nraised both Jcpara and Jcperp by more than 300% at 5T, while Birr was enhanced\nby 0.7 T. At 4.2K, the enhancement of Jc was smaller, but still reached 53% at\n10 T. After applying pressures up to 6.5 GPa, the mass density dm of the\nunreacted (B+Mg) mixture inside the filaments reached 96% of the theoretical\ndensity. After reaction under atmospheric pressure, this corresponds to a\nhighest mass density df in the MgB2 filaments of 73%. After reaction, the\nelectrical resistance of wires submitted to cold densification was found to\ndecrease, reflecting an improved connectivity. A quantitative correlation\nbetween filament mass density and the physical properties was established.\nMonofilamentary rectangular wires with aspect ratios a/b < 1.25 based on low\nenergy ball milled powders exhibited very low anisotropy ratios, Gamma =\nJcpara/Jcperp being < 1.4 at 4.2 K and 10T. The present results can be\ngeneralized to alloyed MgB2 wires, as demonstrated on a wire with B4C\nadditives. Based on the present data, it follows that cold densification has\nthe potential of further improving the highest Jcpara and Jcperp values\nreported so far for in situ MgB2 tapes and wires with SiC and C additives.\nInvestigations are under work in our laboratory to determine whether the\ndensification method CHPD can be applied to longer wire or tape lengths."
    },
    {
        "anchor": "Optical nano-imaging of gate-tuneable graphene plasmons: The ability to manipulate optical fields and the energy flow of light is\ncentral to modern information and communication technologies, as well as\nquantum information processing schemes. However, as photons do not possess\ncharge, controlling them efficiently by electrical means has so far proved\nelusive. A promising way to achieve electric control of light could be through\nplasmon polaritons - coupled excitations of photons and charge carriers - in\ngraphene. In this two-dimensional sheet of carbon atoms, it is expected that\nplasmon polaritons and their associated optical fields can be readily tuned\nelectrically by varying the graphene carrier density. While optical graphene\nplasmon resonances have recently been investigated spectroscopically, no\nexperiments so far have directly resolved propagating plasmons in real space.\nHere, we launch and detect propagating optical plasmons in tapered graphene\nnanostructures using near-field scattering microscopy with infrared excitation\nlight. We provide real-space images of plasmonic field profiles and find that\nthe extracted plasmon wavelength is remarkably short - over 40 times smaller\nthan the wavelength of illumination. We exploit this strong optical field\nconfinement to turn a graphene nanostructure into a tunable resonant plasmonic\ncavity with extremely small mode volume. The cavity resonance is controlled\nin-situ by gating the graphene, and in particular, complete switching on and\noff of the plasmon modes is demonstrated, thus paving the way towards\ngraphene-based optical transistors. This successful alliance between\nnanoelectronics and nano-optics enables the development of unprecedented active\nsubwavelength-scale optics and a plethora of novel nano-optoelectronic devices\nand functionalities, such as tunable metamaterials, nanoscale optical\nprocessing and strongly enhanced light-matter interactions for quantum devices\nand (bio)sensors.",
        "positive": "Magneto-thermal-switching properties of superconducting Nb: Recently, thermal switching has been extensively studied because it is a key\ncomponent for thermal management in electronic devices. Here, we show a huge\nmagneto-thermal-switching ratio (MTSR) in pure Nb at temperatures lower than\nits superconducting transition temperature (Tc = 9.2 K). The MTSR increases\nwith decreasing temperature, and MTSR of 650% was observed at T = 2.5 K under H\n= 4.0 kOe. The thermal switching in superconductors with the huge MTSR will be\nuseful for improvement of the performance of low-temperature electronic\ndevices."
    },
    {
        "anchor": "Evolving Devil's staircase magnetization from tunable charge density\n  waves in nonsymmorphic Dirac semimetals: While several magnetic topological semimetals have been discovered in recent\nyears, their band structures are far from ideal, often obscured by trivial\nbands at the Fermi energy. Square-net materials with clean, linearly dispersing\nbands show potential to circumvent this issue. CeSbTe, a square-net material,\nfeatures multiple magnetic field-controllable topological phases. Here, it is\nshown that in this material, even higher degrees of tunability can be achieved\nby changing the electron count at the square-net motif. Increased electron\nfilling results in structural distortion and formation of charge density waves\n(CDWs). The modulation wave-vector evolves continuously leading to a region of\nmultiple discrete CDWs and a corresponding complex \"Devil's staircase\" magnetic\nground state. A series of fractionally quantized magnetization plateaus are\nobserved, which implies direct coupling between CDW and a collective\nspin-excitation. It is further shown that the CDW creates a robust idealized\nnon-symmorphic Dirac semimetal, thus providing access to topological systems\nwith rich magnetism.",
        "positive": "High oxygen pressure floating zone growth and crystal structure of the\n  layered nickelates R$_4$Ni$_3$O$_{10}$ (R=La, Pr): Single crystals of the metallic Ruddlesden-Popper trilayer nickelates\nR$_4$Ni$_3$O$_{10}$ (R=La, Pr) were successfully grown using an optical-image\nfloating zone furnace under oxygen pressure (pO$_2$) of 20 bar for\nLa$_4$Ni$_3$O$_{10}$ and 140 bar for Pr$_4$Ni$_3$O$_{10}$. A combination of\nsynchrotron and laboratory x-ray single crystal diffraction, high-resolution\nsynchrotron x-ray powder diffraction and measurements of physical properties\nrevealed that R$_4$Ni$_3$O$_{10}$ (R=La, Pr) crystallizes in the monoclinic\n$P$2$_1$/$a$ (Z=2) space group at room temperature, and that a metastable\northorhombic phase ($Bmab$) can be trapped by post-growth rapid cooling. Both\nLa$_4$Ni$_3$O$_{10}$ and Pr$_4$Ni$_3$O$_{10}$ crystals undergo a metal-to-metal\ntransition (MMT) below room temperature. In the case of Pr$_4$Ni$_3$O$_{10}$,\nthe MMT is found at ~157.6 K. For La$_4$Ni$_3$O$_{10}$, the MMT depends on the\nlattice symmetry: 147.5 K for $Bmab$ vs. 138.6 K for $P$2$_1$/$a$. Lattice\nanomalies were found at the MMT that, when considered together with the\npronounced dependence of the transition temperature on subtle structural\ndifferences between $Bmab$ and $P$2$_1$/$a$ phases, demonstrates a not\ninsignificant coupling between electronic and lattice degrees of freedom in\nthese trilayer nickelates."
    },
    {
        "anchor": "Implementation of an all-electron GW approximation based on the PAW\n  method without plasmon pole approximation: application to Si, SiC, AlAs,\n  InAs, NaH and KH: A new implementation of the GW approximation (GWA) based on the all-electron\nProjector-Augmented-Wave method (PAW) is presented, where the screened Coulomb\ninteraction is computed within the Random Phase Approximation (RPA) instead of\nthe plasmon-pole model. Two different ways of computing the self-energy are\nreported. The method is used successfully to determine the quasiparticle\nenergies of six semiconducting or insulating materials: Si, SiC, AlAs, InAs,\nNaH and KH. To illustrate the novelty of the method the real and imaginary part\nof the frequency-dependent self-energy together with the spectral function of\nsilicon are computed. Finally, the GWA results are compared with other\ncalculations, highlighting that all-electron GWA results can differ markedly\nfrom those based on pseudopotential approaches.",
        "positive": "Plasmon-induced demagnetization and magnetic switching in nickel\n  nanoparticle arrays: We report on the manipulation of magnetization by femtosecond laser pulses in\na periodic array of cylindrical nickel nanoparticles. By performing experiments\nat different wavelength, we show that the excitation of collective surface\nplasmon resonances triggers demagnetization in zero field or magnetic switching\nin a small perpendicular field. Both magnetic effects are explained by\nplasmon-induced heating of the nickel nanoparticles to their Curie temperature.\nModel calculations confirm the strong correlation between the excitation of\nsurface plasmon modes and laser-induced changes in magnetization."
    },
    {
        "anchor": "Rheological and Electrical Transitions in Carbon Nanotube/Epoxy\n  Suspensions: The rheological and electrical properties of suspensions of carbon nanotubes\nin an uncured epoxy resin were investigated by means of shear rheology and\nimpedance spectroscopy. It was found that above an onset CNT weight fraction\n(0.1 wt %), the steady viscosity increased with CNT loading and presented a\nshear thinning behaviour. The concentration dependence of viscosity changed\nfrom a power law to an exponential with increasing shear rate, indicating a\nloss of interaction between aggregates and CNT network breakage. The\nfluid-to-solidlike and insulator-to-conductor transitions occurred in the same\nCNT weight fraction range between 0.5 and 0.6 wt %. The correspondence of these\ntransitions was explained by the reduction of contact resistance between CNT by\nstiffening of the CNT network leading to improved electronic transport.",
        "positive": "Strained band edge characteristics from hybrid density functional theory\n  and empirical pseudopotentials: GaAs, GaSb, InAs and InSb: The properties of a semiconductor get drastically modified when the crystal\npoint group symmetry is broken under an arbitrary strain. We investigate the\nfamily of semiconductors consisting of GaAs, GaSb, InAs and InSb, considering\ntheir electronic band structure and deformation potentials subject to various\nstrains based on hybrid density functional theory. Guided by these\nfirst-principles results, we develop strain-compliant local pseudopotentials\nfor use in the empirical pseudopotential method (EPM). We demonstrate that the\nnewly proposed empirical pseudopotentials perform well close to band edges and\nunder anisotropic crystal deformations. Using EPM, we explore the heavy\nhole-light hole mixing characteristics under different stress directions which\nmay be useful in manipulating their transport properties and optical selection\nrules. The very low 5 Ry cutoff targeted in the generated pseudopotentials\npaves the way for large-scale EPM-based electronic structure computations\ninvolving these lattice mismatched constituents."
    },
    {
        "anchor": "Statistical equilibrium measures in micromagnetics: We derive an equilibrium statistical theory for the macroscopic description\nof a ferromagnetic material at positive finite temperatures. Our formulation\ndescribes the most-probable equilibrium macrostates that yield a coherent\ndeterministic large-scale picture varying at the size of the domain, as well as\nit captures the effect of random spin fluctuations caused by the thermal noise.\nWe discuss connections of the proposed formulation to the Landau-Lifschitz\ntheory and to the studies of domain formation based on Monte Carlo lattice\nsimulations.",
        "positive": "Interfacial current-induced torques in Pt/Co/GdOx: Current-driven domain wall (DW) motion is investigated in Pt/Co/GdOx\nnanostrips with perpendicular magnetic anisotropy. Measurements of the\npropagation field and the energy barrier for thermally activated DW motion\nreveal a large current-induced torque equivalent to an out-of-plane magnetic\nfield of ~60 Oe per 10^11 A/m^2. This same field-to-current scaling is shown to\nhold in both the slow thermally activated and fast near-flow regimes of DW\nmotion. The current-induced torque decreases with 4 {\\AA} of Pt decorating the\nCo/GdOx interface and vanishes entirely with Pt replacing GdOx, suggesting that\nthe Co/GdOx interface contributes directly to highly efficient current-driven\nDW motion."
    },
    {
        "anchor": "Large resistivity change and phase transition in LiMnAs: Antiferromagnetic semiconductors are new alternative materials for spintronic\napplications and spin valves. In this work, we report a detailed investigation\nof two antiferromagnetic semiconductors AMnAs (A = Li, LaO), which are\nisostructural to the well-known LiFeAs and LaOFeAs superconductors. Here we\npresent a comparison between the structural, magnetic, and electronic\nproperties of LiMnAs, LaOMnAs and related materials. Interestingly, both LiMnAs\nand LaOMnAs show a variation in resistivity with more than five orders of\nmagnitude, making them particularly suitable for use in future electronic\ndevices. From neutron and X-ray diffraction measurements on LiMnAs we have\nobserved a magnetic phase transition corresponding to the Neel temperature of\n373.8 K, and a structural transition from the tetragonal to the cubic phase at\n768 K. These experimental results are supported by density functional theory\n(DFT) calculations.",
        "positive": "Capping of Nanoparticles: An Alternative Approach for Reducing\n  Nanoparticle Toxicity in Plants: The present era has witnessed a new dawn in technology innovations with the\nentry and use of nanomaterials in the industries and in the products used and\nto be used in day-to-day life creating a huge possibility of ending up in the\nfood chain. Several studies in the past has highlighted toxicity of\nnanomaterials due to their size. However, we cannot stop technological\nadvancements provided by the nanomaterials fulfilling human needs but can find\na solution to the toxicity of the nanomaterials for a better future and safe\nenvironment. In this study, we propose capping of nanomaterials to reduce the\ntoxicity without compromising their functionality. Capping of the nanomaterials\nis used to passivate nanomaterials but the same capping also helps in the\nreduction of surface reactivity leading to low toxicity. We studied\nphytotoxicity in the presence of one of the most extensively used metal\nnanoparticles (copper nanoparticles) on Eleusine corcana G. (finger millet) and\nPaspalum scrobiculatum L. (Kodo millet). Copper nanoparticles were synthesized\nby the hydrometallurgical methods. Ethylenediaminetetraacetic acid (EDTA) was\nused to cap the nanoparticles during the synthesis. In vitro studies results\nshowed that the toxicity of copper nanoparticles is significantly reduced after\ncapping. Anti-bacterial activity studies showed no change in efficacy of copper\nnanoparticles after capping. This study highlights the use of capping to reduce\nthe toxicity of nanomaterials without sacrificing their required applicability."
    },
    {
        "anchor": "Regimes of Precursor-Mediated Epitaxial Growth: A discussion of epitaxial growth is presented for those situations (OMVPE,\nCBE, ALE, MOMBE, GSMBE, etc.) when the kinetics of surface processes associated\nwith molecular precursors may be rate limiting. Emphasis is placed on the\nidentification of various {\\it characteristic length scales} associated with\nthe surface processes. Study of the relative magnitudes of these lengths\npermits one to identify regimes of qualitatively different growth kinetics as a\nfunction of temperature and deposition flux. The approach is illustrated with a\nsimple model which takes account of deposition, diffusion, desorption,\ndissociation, and step incorporation of a single precursor species, as well as\nthe usual processes of atomic diffusion and step incorporation. Experimental\nimplications are discussed in some detail.",
        "positive": "Unfolding of vortices into topological stripes in a multiferroic\n  material: Multiferroic hexagonal RMnO3 (R=rare earths) crystals exhibit dense networks\nof vortex lines at which six domain walls merge. While the domain walls can be\nreadily moved with an applied electric field, the vortex cores were so far\nimpossible to control. Our experiments demonstrate that shear strain induces a\nMagnus-type force pulling vortices and antivortices in opposite directions and\nunfolding them into a topological stripe domain state. We discuss the analogy\nbetween this effect and the current-driven dynamics of vortices in\nsuperconductors and superfluids."
    },
    {
        "anchor": "Combinatorial sputter synthesis of single-phase La(XYZ)O$_{3\\pm\u03c3}$\n  perovskite thin film libraries: a new platform for materials discovery: Compositionally complex perovskites provide the opportunity to develop stable\nand active catalysts for electrochemical applications. The challenge lies in\nthe identification of single-phase perovskites with optimized composition for\nhigh electrical conductivity. Leveraging a recently discovered effect of\nself-organized thin film growth during reactive sputtering, La-Co-Mn-O and\nLa-Co-Mn-Fe-O perovskite (ABO3) thin film materials libraries are synthesized.\nThese show phase-pure La-perovskites over a wide range of chemical composition\nvariation for the B-site elements for deposition temperatures equal to or\nhigher than 300$^\\circ$C. It is demonstrated that this approach enables the\ndiscovery and tailoring of chemical compositions for desired optical bandgap\nand electrical conductivity, and thereby opens the path for the targeted\ndevelopment of e.g. new high-performance electrocatalysts.",
        "positive": "Prediction of $\\textrm{CO}_2$ Adsorption in Nano-Pores with Graph Neural\n  Networks: We investigate the graph-based convolutional neural network approach for\npredicting and ranking gas adsorption properties of crystalline Metal-Organic\nFramework (MOF) adsorbents for application in post-combustion capture of\n$\\textrm{CO}_2$. Our model is based solely on standard structural input files\ncontaining atomistic descriptions of the adsorbent material candidates. We\nconstruct novel methodological extensions to match the prediction accuracy of\nclassical machine learning models that were built with hundreds of features at\nmuch higher computational cost. Our approach can be more broadly applied to\noptimize gas capture processes at industrial scale."
    },
    {
        "anchor": "On the stabilization of ion sputtered surfaces: The classical theory of ion beam sputtering predicts the instability of a\nflat surface to uniform ion irradiation at any incidence angle. We relax the\nassumption of the classical theory that the average surface erosion rate is\ndetermined by a Gaussian response function representing the effect of the\ncollision cascade and consider the surface dynamics for other\nphysically-motivated response functions. We show that although instability of\nflat surfaces at any beam angle results from all Gaussian and a wide class of\nnon-Gaussian erosive response functions, there exist classes of modifications\nto the response that can have a dramatic effect. In contrast to the classical\ntheory, these types of response render the flat surface linearly stable, while\nimperceptibly modifying the predicted sputter yield vs. incidence angle. We\ndiscuss the possibility that such corrections underlie recent reports of a\n``window of stability'' of ion-bombarded surfaces at a range of beam angles for\ncertain ion and surface types, and describe some characteristic aspects of\npattern evolution near the transition from unstable to stable dynamics. We\npoint out that careful analysis of the transition regime may provide valuable\ntests for the consistency of any theory of pattern formation on ion sputtered\nsurfaces.",
        "positive": "Ultrafast reduction in exchange interaction by a laser pulse:\n  Alternative path to femtomagnetism: Since the beginning of femtomagnetism, it has been hotly debated how an\nultrafast laser pulse can demagnetize a sample and switch its spins within a\nfew hundred femtoseconds, but no consensus has been reached. In this paper, we\npropose that an ultrafast reduction in the exchange interaction by a\nfemtosecond laser pulse is mainly responsible for demagnetization and spin\nswitching. The key physics is that the dipole selection rule demands two\ndistinctive electron configurations for the ground and excited states and\nconsequently changes the exchange interaction. Although the exchange\ninteraction change is almost instantaneous, its effect on the spin is delayed\nby the finite spin wave propagation. Consistent with the experimental\nobservation, the delay becomes longer with a stronger exchange interaction\npulse. In spin-frustrated systems, the effect of the exchange interaction\nchange is even more dramatic, where the spin can be directly switched from one\ndirection to the other. Therefore, our theory has the potential to explain the\nessence of major observations in rare-earth transition metal compounds for the\nlast seven years. Our findings are likely to motivate further research in the\nquest of the origin of femtomagnetism."
    },
    {
        "anchor": "Nonlocal Homogenization Model for a Periodic Array of Epsilon-Negative\n  Rods: We propose an effective permittivity model to homogenize an array of long\nthin epsilon-negative rods arranged in a periodic lattice. It is proved that\nthe effect of spatial dispersion in this electromagnetic crystal cannot be\nneglected, and that the medium supports dispersionless modes that guide the\nenergy along the rod axes. It is suggested that this effect may be used to\nachieve sub-wavelength imaging at the infrared and optical domains. The\nreflection problem is studied in detail for the case in which the rods are\nparallel to the interfaces. Full wave numerical simulations demonstrate the\nvalidity and accuracy of the new model.",
        "positive": "Three-Dimensional Nanotransmission Lines at Optical Frequencies: A\n  Recipe for Broadband Negative-Refraction Optical Metamaterials: Here we apply the optical nanocircuit concepts to design and analyze in\ndetail a three-dimensional (3-D) plasmonic nanotransmission line network that\nmay act as a negative-refraction broadband metamaterial at infrared and optical\nfrequencies. After discussing the heuristic concepts at the basis of our\ntheory, we show full-wave analytical results of the expected behavior of such\nmaterials, which show increased bandwidth and relative robustness to losses.\nThe possibility and constraints of getting a 3-D fully isotropic response is\nalso explored and conditions for minimal losses and increased bandwidth are\ndiscussed. Full-wave analytical results for some design examples employing\nrealistic plasmonic materials at infrared and optical frequencies are also\npresented, and a case of sub-wavelength imaging system using a slab of this\nmaterial is numerically investigated."
    },
    {
        "anchor": "Raman Spectroscopy and Aging of the Low-Loss Ferrimagnet Vanadium\n  Tetracyanoethylene: Vanadium tetracyanoethylene (V[TCNE]$_{x}$, $x\\approx 2$) is an organic-based\nferrimagnet with a high magnetic ordering temperature $\\mathrm{T_C>600 ~K}$,\nlow magnetic damping, and growth compatibility with a wide variety of\nsubstrates. However, similar to other organic-based materials, it is sensitive\nto air. Although encapsulation of V[TCNE]$_{x}$ with glass and epoxy extends\nthe film lifetime from an hour to a few weeks, what is limiting its lifetime\nremains poorly understood. Here we characterize encapsulated V[TCNE]$_{x}$\nfilms using confocal microscopy, Raman spectroscopy, ferromagnetic resonance\nand SQUID magnetometry. We identify the relevant features in the Raman spectra\nin agreement with \\textit{ab initio} theory, reproducing $\\mathrm{C=C,C\\equiv\nN}$ vibrational modes. We correlate changes in the effective dynamic\nmagnetization with changes in Raman intensity and in photoluminescence. Based\non changes in Raman spectra, we hypothesize possible structural changes and\naging mechanisms in V[TCNE]$_x$. These findings enable a local optical probe of\nV[TCNE]$_{x}$ film quality, which is invaluable in experiments where assessing\nfilm quality with local magnetic characterization is not possible.",
        "positive": "Newly synthesized Ti5Al2C3: Electronic and optical properties by\n  first-principles method: A theoretical study of the newly identified Ti5Al2C3 belonging to the MAX\nphases has been performed by using the first-principles pseudopotential\nplane-wave method within the generalized gradient approximation (GGA). The\nenergy band structure and optical properties are reported for the first time.\nIt is seen that Ti 3d electrons mainly contribute to the DOS at the Fermi\nlevel, and should be involved in the conduction properties. The parameters of\noptical properties (dielectric function, absorption spectrum, conductivity,\nenergy-loss spectrum and reflectivity) for Ti5Al2C3 are calculated and\ndiscussed. The material has a large positive static dielectric constant of 130\nwhich indicates it to be a good dielectric material. Further the reflectivity\nof Ti5Al2C3 is high in the infrared-visible-UV region up to ~ 9.7 eV showing\npromise as a good coating material to avoid solar heating.\n  Keywords: A: Ti5Al2C3; B: First-principles; C: Electronic structure; C:\nOptical properties"
    },
    {
        "anchor": "Tuning Structural and Electronic Properties of Metal-Organic Framework 5\n  by Metal Substitution and Linker Functionalization: The chemical flexibility of metal-organic frameworks (MOFs) offers an ideal\nplatform to tune structure and composition for specific applications, from gas\nsensing to catalysis and from photoelectric conversion to energy storage. This\nvariability gives rise to a large configurational space that can be efficiently\nexplored using high-throughput computational methods. In this work, we\ninvestigate from first principles the structural and electronic properties of\nMOF-5 variants obtained by replacing Zn with Be, Mg, Cd, Ca, Sr, and Ba, and by\nfunctionalizing the originally H-passivated linkers with CH$_3$, NO$_2$, Cl,\nBr, NH$_2$, OH, and COOH groups. To build and analyze the resulting 56\nstructures, we employ density-functional theory calculations embedded in an\nin-house developed library for automatized calculations. Our findings reveal\nthat structural properties are mainly defined by metal atoms and large\nfunctional groups which distort the lattice and modify coordination. Stability\nis largely influenced by functionalization and enhanced by COOH and OH groups\nwhich promote the formation of hydrogen bonds. The charge distribution within\nthe linker is especially influenced by functional groups with\nelectron-withdrawing character while the metal nodes play a minor role.\nLikewise, the band-gap size is crucially determined by ligand\nfunctionalization. The smallest gaps are found with NH$_2$ and OH groups which\nintroduce localized orbitals at the top of the valence band. This\ncharacteristic makes these functionalizations particularly promising for the\ndesign of MOF-5 variants with enhanced gas uptake and sensing properties.",
        "positive": "Magneto-structural correlations in a systematically disordered B2\n  lattice: Ferromagnetism in certain B2 ordered alloys such as Fe$_{60}$Al$_{40}$ can be\nswitched on, and tuned, via antisite disordering of the atomic arrangement. The\ndisordering is accompanied by a $\\sim$1 % increase in the lattice parameter.\nHere we performed a systematic disordering of B2 Fe$_{60}$Al$_{40}$ thin films,\nand obtained correlations between the order parameter ($S$), lattice parameter\n($a_0$), and the induced saturation magnetization ($M_{s}$). As the lattice is\ngradually disordered, a critical point occurs at 1-$S$=0.6 and $a_0$=291 pm,\nwhere a sharp increase of the $M_{s}$ is observed. DFT calculations suggest\nthat below the critical point the system magnetically behaves as it would still\nbe fully ordered, whereas above, it is largely the increase of $a_0$ in the\ndisordered state that determines the $M_{s}$. The insights obtained here can be\nuseful for achieving tailored magnetic properties in alloys through\ndisordering."
    },
    {
        "anchor": "Tuning the circularly polarized photoluminescence of chiral 2D\n  perovskites by high pressure: Chiral 2D perovskites are of great interest as circularly polarized\nphotoluminescence materials, but these materials generally exhibit weak CPL\nunder ambient conditions. Several studies have shown that the degree of CPL can\nbe enhanced by using strong external magnetic fields or low temperature. Here\nwe report a method to tune the circularly polarized photoluminescence of chiral\n2D perovskites by utilizing extreme high pressure. The (S- and R-MBA)2PbI4\nperovskites exhibited good optical tunability with pressure in term of PL\nwavelength, intensity and bandgap. Polarization-resolved photoluminescence\nmeasurements shown that the degree of CPL was increased from nearly zero at\nambient pressure to as high as 10% at 8.5 GPa. ADXRD and Raman results\nindicated that the structural distortion and Increased interlayer coupling are\nresponsible for the enhanced chirality when pressure is applied. Our findings\nprovide a new approach to adjusting CPL materials and show potential\napplications in next generation of CPL devices.",
        "positive": "Spontaneous nucleation and growth of GaN nanowires: Fundamental role of\n  crystal polarity: We experimentally investigate whether crystal polarity affects the growth of\nGaN nanowires in plasma-assisted molecular beam epitaxy and whether their\nformation has to be induced by defects. For this purpose, we prepare smooth and\ncoherently strained AlN layers on 6H-SiC(0001) and SiC(000$\\bar{1}$) substrates\nto ensure a well-defined polarity and an absence of structural and\nmorphological defects. On N-polar AlN, a homogeneous and dense N-polar GaN\nnanowire array forms, evidencing that GaN nanowires form spontaneously in the\nabsence of defects. On Al-polar AlN, we do not observe the formation of\nGa-polar GaN NWs. Instead, sparse N-polar GaN nanowires grow embedded in a\nGa-polar GaN layer. These N-polar GaN nanowires are shown to be accidental in\nthat the necessary polarity inversion is induced by the formation of Si$_{x}$N.\nThe present findings thus demonstrate that spontaneously formed GaN nanowires\nare irrevocably N-polar. Due to the strong impact of the polarity on the\nproperties of GaN-based devices, these results are not only essential to\nunderstand the spontaneous formation of GaN nanowires but also of high\ntechnological relevance."
    },
    {
        "anchor": "Ultrafast light switching of ferromagnetism in EuSe: We demonstrate that light resonant with the bandgap forces the\nantiferromagnetic semiconducor EuSe to enter ferromagnetic alignment in the\npicosecond time scale. A photon generates an electron-hole pair, whose electron\nforms a supergiant spin polaron of magnetic moment of nearly 6,000 Bohr\nmagnetons. By increasing the light intensity, the whole of the sample can be\nfully magnetized. The key to the novel large photoinduced magnetization\nmechanism is the huge enhancement of the magnetic susceptibility when both\nantiferromagnetic and ferromagnetic interactions are present in the material,\nand are of nearly equal magnitude, as is the case in EuSe.",
        "positive": "Nanoindentation-Induced Phase Transformation in Silicon: Nanoindentation-induced phase transformation in silicon has been studied. A\nseries of nanoindentations were made with the sharp diamond Berkovich tip.\nDuring nanoindentations, maximum load ranged from 2000 $\\mu$N to 5000 $\\mu$N,\nwith a 1000 $\\mu$N/sec loading rate. Slow unloading rate at 100$\\mu$N/sec was\nchosen to favor the formation of the crystalline end phases, high pressure\nphase (Si-III and Si-XII). Fast unloading rate at 1000$\\mu$N/sec was used to\nobtain amorphous phase. The phase transformation was examined by Raman\nspectroscopy and plan-view transmission electron microscopy (TEM). HPP have\nbeen identified even if no \"pop-in\" and \"pop-out\" observed in load-depth\ncharacteristics curves. HPP appeared in c-Si when the maximum load up to 3000\n$\\mu$N. TEM images have been revealed that the optimization HPP transformation\nin c-Si at the nanoscale occurred when the maximum load applied at 5000 $\\mu$N."
    },
    {
        "anchor": "Double stochastic resonance in conductors with narrow conduction band: Results are presented of studying the stochastic resonance (SR) in conductors\nwith bcc lattice and narrow conduction band. In such materials, SR has a\nfeature, namely, the weak-signal gain as a function of the additive and\nnon-correlated noise level can have two maxima, i.e., double SR takes place.",
        "positive": "Mechanical properties of the magnetocaloric intermetallic LaFe11.2Si1.8\n  alloy at different length scales: In this work the global and local mechanical properties of the magnetocaloric\nintermetallic LaFe11.2Si1.8 alloy are investigated by a combination of\ndifferent testing and characterization techniques in order to shed light on the\npartly contradictory data in recent literature. Macroscale compression tests\nwere performed to illuminate the global fracture behavior and evaluate it\nstatistically. LaFe11.2Si1.8 demonstrates a brittle behavior with fracture\nstrains below 0.6 % and widely distributed fracture stresses of 180-620 MPa\nleading to a Weibull modulus of m = 2 to 6. The local mechanical properties,\nsuch as hardness and Youngs modulus, of the main and secondary phases are\nexamined by nanoindentation and Vickers microhardness tests. An intrinsic\nstrength of the main magnetocaloric phase of at least 2 GPa is estimated. The\nsignificantly lower values obtained by compression tests are attributed to the\ndetrimental effect of pores, microcracks, and secondary phases. Microscopic\nexamination of indentation-induced cracks reveals that ductile alpha-Fe\nprecipitates act as crack arrestors whereas pre-existing cracks at La-rich\nprecipitates provide numerous \"weak links\" for the initiation of catastrophic\nfracture. The presented systematic study extends the understanding of the\nmechanical reliability of La(Fe, Si)13 alloys by revealing the correlations\nbetween the mechanical behavior of macroscopic multi-phase samples and the\nlocal mechanical properties of the single phases."
    },
    {
        "anchor": "Engineering the interlayer exchange coupling in magnetic trilayers: When the thickness of metal film approaches the nanoscale, itinerant carriers\nresonate between its boundaries and form quantum well states (QWSs), which are\ncrucial to account for the film electrical, transport and magnetic properties.\nBesides the classic origin of particle-in-a-box, the QWSs are also susceptible\nto the crystal structures that affect the quantum resonance. Here we\ninvestigate the QWSs and the magnetic interlayer exchange coupling (IEC) in the\nFe/Ag/Fe (001) trilayer from first-principles calculations. We find that the\ncarriers at the Brillouin-zone center (belly) and edge (neck) separately form\nelectron- and hole-like QWSs that give rise to an oscillatory feature for the\nIEC as a function of the Ag-layer thickness with long and short periods. Since\nthe QWS formation sensitively depends on boundary conditions, one can switch\nbetween these two IEC periods by changing the Fe-layer thickness. These\nfeatures, which also occur in the magnetic trilayers with other noble-metal\nspacers, open a new degree of freedom to engineer the IEC in magnetoresistance\ndevices.",
        "positive": "Synthesis of Oxidation-Resistant Electrochemical-Active Copper Nanowires\n  Using Phenylenediamine Isomers: Phenylenediamine (PDA) was chosen as a coordinating, reducing, and capping\nagent to effectively direct growth and protect against oxidation of Cu\nnanowires (Cu NWs) in an aqueous solution. PDA was found to reduce Cu (II) to\nCu (I) at room temperature, and stabilize the resulting Cu (I) by forming a\ncoordination complex. The presence of a stable Cu (I) complex is the key step\nin the synthesis of Cu NWs under mild conditions. Different PDA isomers lead to\ndifferent growth paths of forming Cu NWs. Both pPDA and mPDA-synthesized Cu NWs\nwere covered with a thin layer of polyphenylenediamine and show excellent\nanti-oxidation properties, even in the presence of water. The usefulness of the\npresent and electrochemical active Cu NWs for a variety of nanotechnology\napplications is discussed."
    },
    {
        "anchor": "Tunable magnetically induced transparency spectra in magnon-magnon\n  coupled Y3Fe5O12/permalloy bilayers: Hybrid magnonic systems host a variety of characteristic quantum phenomena\nsuch as the magnetically-induced transparency (MIT) and Purcell effect, which\nare considered useful for future coherent quantum information processing. In\nthis work, we experimentally demonstrate a tunable MIT effect in the\nY3Fe5O12(YIG)/Permalloy(Py) magnon-magnon coupled system via changing the\nmagnetic field orientations. By probing the magneto-optic effects of Py and\nYIG, we identify clear features of MIT spectra induced by the mode\nhybridization between the uniform mode of Py and the perpendicular standing\nspin-wave modes of YIG. By changing the external magnetic field orientations,\nwe observe a tunable coupling strength between the YIG's spin-wave modes and\nthe Py's uniform mode, upon the application of an out-of-plane magnetic field.\nThis observation is theoretically interpreted by a geometrical consideration of\nthe Py and YIG magnetization under the oblique magnetic field even at a\nconstant interfacial exchange coupling. Our findings show high promise for\ninvestigating tunable coherent phenomena with hybrid magnonic platforms.",
        "positive": "Ultrafast Photoinduced Band Splitting and Carrier Dynamics in Chiral\n  Tellurium Nanosheets: Trigonal tellurium (Te) is a chiral semiconductor that lacks both mirror and\ninversion symmetries, resulting in complex band structures with Weyl crossings\nand unique spin textures. Detailed time-resolved polarized reflectance\nspectroscopy is used to investigate its band structure and carrier dynamics.\nThe polarized transient spectra reveal optical transitions between the\nuppermost spin-split H4 and H5 and the degenerate H6 valence bands (VB) and the\nlowest degenerate H6 conduction band (CB) as well as a higher energy transition\nat the L-point. Surprisingly, the degeneracy of the H6 CB (a proposed Weyl\nnode) is lifted and the spin-split VB gap is reduced upon photoexcitation\nbefore relaxing to equilibrium as the carriers decay. Using ab initio density\nfunctional theory (DFT) calculations we conclude that the dynamic band\nstructure is caused by a photoinduced shear strain in the Te film that breaks\nthe screw symmetry of the crystal. The band-edge anisotropy is also reflected\nin the hot carrier decay rate, which is a factor of two slower along c-axis\nthan perpendicular to it. The majority of photoexcited carriers near the\nband-edge are seen to recombine within 30 ps while higher lying transitions\nobserved near 1.2 eV appear to have substantially longer lifetimes, potentially\ndue to contributions of intervalley processes in the recombination rate. These\nnew findings shed light on the strong correlation between photoinduced carriers\nand electronic structure in anisotropic crystals, which opens a potential\npathway for designing novel Te-based devices that take advantage of the\ntopological structures as well as strong spin-related properties."
    },
    {
        "anchor": "Nearly strain-free heteroepitaxial system for fundamental studies of\n  pulsed laser deposition: EuTiO3 on SrTiO3: High quality epitaxial thin-films of EuTiO3 have been grown on the (001)\nsurface of SrTiO3 using pulsed laser deposition. In situ x-ray reflectivity\nmeasurements reveal that the growth is two-dimensional and enable real-time\nmonitoring of the film thickness and roughness during growth. The film\nthickness, surface mosaic, surface roughness, and strain were characterized in\ndetail using ex situ x-ray diffraction. The thicnkess and composition were\nconfirmed with Rutherford Backscattering. The EuTiO3 films grow\ntwo-dimensionally, epitaxially, pseudomorphically, with no measurable in-plane\nlattice mismatch.",
        "positive": "Hidden type-II Weyl points in the Weyl semimetal NbP: As one of Weyl semimetals discovered recently, NbP exhibits two groups of\nWeyl points with one group lying inside the $k_z=0$ plane and the other group\nstaying away from this plane. All Weyl points have been assumed to be type-I,\nfor which the Fermi surface shrinks into a point as the Fermi energy crosses\nthe Weyl point. In this work, we have revealed that the second group of Weyl\npoints are actually type-II, which are found to be touching points between the\nelectron and hole pockets in the Fermi surface. Corresponding Weyl cones are\nstrongly tilted along a line approximately $17^\\circ$ off the $k_z$ axis in the\n$k_x - k_z$ (or $k_y - k_z$) plane, violating the Lorentz symmetry but still\ngiving rise to Fermi arcs on the surface. Therefore, NbP exhibits both type-I\n($k_z=0$ plane) and type-II ($k_z \\neq 0$ plane) Weyl points."
    },
    {
        "anchor": "Semiconductor-to-metal transition in bilayer MoSi$_2$N$_4$ and\n  WSi$_2$N$_4$ with strain and electric field: With exceptional electrical and mechanical properties and at the same time\nair-stability, layered MoSi2N4 has recently draw great attention. However, band\nstructure engineering via strain and electric field, which is vital for\npractical applications, has not yet been explored. In this work, we show that\nthe biaxial strain and external electric field are effective ways for the band\ngap engineering of bilayer MoSi$_2$N$_4$ and WSi$_2$N$_4$. It is found that\nstrain can lead to indirect band gap to direct band gap transition. On the\nother hand, electric field can result in semiconductor to metal transition. Our\nstudy provides insights into the band structure engineering of bilayer\nMoSi$_2$N$_4$ and WSi$_2$N$_4$ and would pave the way for its future\nnanoelectronics and optoelectronics applications.",
        "positive": "Optical Identification of Few-Layer Graphene Obtained by Friction: A friction based method is proposed for obtaining graphite layers.\nFreestanding thin structures of graphite containing several layers of graphene\nare obtained by rubbing a graphite rod on the surfaces of NaCl substrate and\nthen dissolving the substrate in water. An optically transparent and\nmechanically strong lamina of few-layer graphene is found in the obtained\nstructures."
    },
    {
        "anchor": "Structural Determination of Multilayer Graphene via Atomic Moir\u00e9\n  Interferometry: Rotational misalignment of two stacked honeycomb lattices produces a moir\\'e\npattern that is observable in scanning tunneling microscopy as a small\nmodulation of the apparent surface height. This is known from experiments on\nhighly-oriented pyrolytic graphite. Here, we observe the combined effect of\nthree-layer moir\\'e patterns in multilayer graphene grown on SiC\n($000\\bar{1}$). Small-angle rotations between the first and third layer are\nshown to produce a \"double-moir\\'e\" pattern, resulting from the interference of\nmoir\\'e patterns from the first three layers. These patterns are strongly\naffected by relative lattice strain between the layers. We model the moir\\'e\npatterns as a beat-period of the mismatched reciprocal lattice vectors and show\nhow these patterns can be used to determine the relative strain between\nlattices, in analogy to strain measurement by optical moir\\'e interferometry.",
        "positive": "4d-element induced improvement of structural disorder and development of\n  weakly re-entrant spin-glass behaviour in NiRuMnSn: The pursuit of efficient spin-polarization in quaternary Heusler alloys with\nthe general formula $XX'YZ$ (where X, $X'$, and Y are transition metals and Z\nis a p-block element), has been a subject of significant scientific interest.\nWhile previous studies shows that isoelectronic substitution of 4d element in\nplace of 3d element in quaternary Heusler alloy, improves the half-metallic\nferromagnetic characteristics, our research on the quaternary Heusler alloy\nNiRuMnSn reveals a strikingly different scenario. In this study, we present a\ndetailed structural analysis of the material using X-ray absorption fine\nstructure (EXAFS) and neutron diffraction (ND) techniques, which confirms the\nformation of a single-phase compound with 50:50 site disorder between Ni/Ru\natoms at 4c/4d sites. Contrary to expectations, our DFT calculations suggests a\nconsiderable decrease in spin-polarization even in the ordered structure.\nAdditionally, we report on the compound's exceptional behavior, displaying a\nrare re-entrant spin glass property below $\\sim$60 K, a unique and intriguing\nfeature for quaternary Heusler-type compounds."
    },
    {
        "anchor": "YBa2Cu3O6+d-originated attraction force giving rise to Meissner effect\n  at 300 K: The exposure of YBCO to an air atmosphere at first at pH2O = 110 Pa and then\nat pH2O = 1 kPa has been used for uncharacteristic and unusual properties of\nYBCO to be observed. Among them there was an increased reactivity of YBCO with\nrespect to water. Besides, it was experimentally obtained extremely excessive\nweight gain of hydrated YBCO samples that was not corresponding to the quantity\nof the absorbed water. Finally, we obtained the significant negative value of\nthe room-temperature (RT) magnetic susceptibility in conventional magnetic\nstudy of the hydrated YBCO that was confirmed by the direct observation of\ndecreasing weight of the same samples that were suspended above the source of\ncontrolled magnetic field (DC mode) at RT. All the results were explained on\nthe basis of an approximate idea that there is a certain source of attractive\nforce inside YBCO, acting on surrounding particles and bodies.",
        "positive": "High thermal conductivity in semiconducting Janus and non-Janus diamanes: Most recently, F-diamane monolayer was experimentally realized by the\nfluorination of bilayer graphene. In this work we elaborately explore the\nelectronic and thermal conductivity responses of diamane lattices with homo or\nhetero functional groups, including: non-Janus C2H, C2F and C2Cl diamane and\nJanus counterparts of C4HF, C4HCl and C4FCl. Noticeably, C2H, C2F, C2Cl, C4HF,\nC4HCl and C4FCl diamanes are found to show electronic diverse band gaps of,\n3.86, 5.68, 2.42, 4.17, 0.86, and 2.05 eV, on the basis of HSE06 method\nestimations. The thermal conductivity of diamane nanosheets was acquired using\nthe full iterative solutions of the Boltzmann transport equation, with\nsubstantially accelerated calculations by employing machine-learning\ninteratomic potentials in obtaining the anharmonic force constants. According\nto our results, the room temperature lattice thermal conductivity of graphene\nand C2H, C2F, C2Cl, C4HF, C4HCl and C4FCl diamane monolayers are estimated to\nbe 3636, 1145, 377, 146, 454, 244 and 196 W/mK, respectively. The underlying\nmechanisms resulting in significant effects of functional groups on the thermal\nconductivity of diamane nanosheets were thoroughly explored. Our results\nhighlight the substantial role of functional groups on the electronic and\nthermal conduction responses of diamane nanosheets."
    },
    {
        "anchor": "Interaction of Molecular Oxygen with Hexagonally Reconstructed Au (001)\n  Surface: Kinetics of molecular oxygen / Au (001) surface interaction has been studied\nat high temperature and near atmospheric pressures of O2 gas with in situ x-ray\nscattering measurements. We find that the hexagonal reconstruction (hex) of Au\n(001) surface lifts to (1x1) in the presence of O2 gas, indicating that the\n(1x1) is more favored when some oxygen atoms present on the surface. The\nmeasured lifting rate constant vs. temperature is found to be highest at\nintermediate temperature exhibiting a 'volcano'-type behavior. At low\ntemperature, the hex-to-(1x1) activation barrier (Eact = 1.3(3) eV) limits the\nlifting. At high temperature, oxygen adsorption energy (Eads = 1.6(2) eV)\nlimits the lifting. The (1x1)-to-hex activation barrier (Ehex = 0.41(14) eV) is\nalso obtained from hex recovery kinetics. The pressure-temperature (PT) surface\nphase diagram obtained in this study shows three regions: hex at low P and T,\n(1x1) at high P and T, and coexistence of the hex and (1x1) at the intermediate\nP and T.",
        "positive": "Short-range order of Br and three-dimensional magnetism in (CuBr)LaNb2O7: We present a comprehensive study of the crystal structure, magnetic\nstructure, and microscopic magnetic model of (CuBr)LaNb2O7, the Br analog of\nthe spin-gap quantum magnet (CuCl)LaNb2O7. Despite similar crystal structures\nand spin lattices, the magnetic behavior and even peculiarities of the atomic\narrangement in the Cl and Br compounds are very different. The high-resolution\nx-ray and neutron data reveal a split position of Br atoms in (CuBr)LaNb2O7.\nThis splitting originates from two possible configurations developed by [CuBr]\nzigzag ribbons. While the Br atoms are locally ordered in the 'ab' plane, their\narrangement along the 'c' direction remains partially disordered. The\npredominant and energetically more favorable configuration features an\nadditional doubling of the 'c' lattice parameter that was not observed in\n(CuCl)LaNb2O7. (CuBr)LaNb2O7 undergoes long-range antiferromagnetic ordering at\nTN=32 K, which is nearly 70% of the leading exchange coupling J4~48 K. The Br\ncompound does not show any experimental signatures of low-dimensional\nmagnetism, because the underlying spin lattice is three-dimensional. The\ncoupling along the 'c' direction is comparable to the couplings in the 'ab'\nplane, even though the shortest Cu--Cu distance along 'c' (11.69 A) is three\ntimes larger than nearest-neighbor distances in the 'ab' plane (3.55 A). The\nstripe antiferromagnetic long-range order featuring columns of parallel spins\nin the 'ab' plane and antiparallel spins along 'c' is verified experimentally\nand confirmed by the microscopic analysis."
    },
    {
        "anchor": "A three dimensional field formulation, and isogeometric solutions to\n  point and line defects using Toupin's theory of gradient elasticity at finite\n  strains: We present a field formulation for defects that draws from the classical\nrepresentation of the cores as force dipoles. We write these dipoles as\nsingular distributions. Exploiting the key insight that the variational setting\nis the only appropriate one for the theory of distributions, we arrive at\nuniversally applicable weak forms for defects in nonlinear elasticity.\nRemarkably, the standard, Galerkin finite element method yields numerical\nsolutions for the elastic fields of defects that, when parameterized suitably,\nmatch very well with classical, linearized elasticity solutions. The true\npotential of our approach, however, lies in its easy extension to generate\nsolutions to elastic fields of defects in the regime of nonlinear elasticity,\nand even more notably for Toupin's theory of gradient elasticity at finite\nstrains(Arch. Rat. Mech. Anal., 11, 385, 1962). In computing these solutions we\nadopt recent numerical work on an isogeometric analytic framework that enabled\nthe first three-dimensional solutions to general boundary value problems of\nToupin's theory (Rudraraju et al. Comp. Meth. App. Mech. Engr., 278, 705,\n2014). We first present exhaustive solutions to point defects, edge and screw\ndislocations, and a study on the energetics of interacting dislocations. Then,\nto demonstrate the generality and potential of our treatment, we apply it to\nother complex dislocation configurations, including loops and low-angle grain\nboundaries.",
        "positive": "Nonmagnetic-Doping Induced Quantum Anomalous Hall Effect in Topological\n  Insulators: Quantum anomalous Hall effect (QAHE) has been experimentally observed in\nmagnetically doped topological insulators. However, ultra-low temperature\n(usually below 300 mK), which is mainly attributed to inhomogeneous magnetic\ndoping, becomes a daunting challenge for potential applications. Here, a\n\\textit{nonmagnetic}-doping strategy is proposed to produce ferromagnetism and\nrealize QAHE in topological insulators. We numerically demonstrated that\nmagnetic moments can be induced by nitrogen or carbon substitution in\nBi$_2$Se$_3$, Bi$_2$Te$_3$, and Sb$_2$Te$_3$, but only nitrogen-doped\nSb$_2$Te$_3$ exhibits long-range ferromagnetism and preserve large bulk band\ngap. We further show that its corresponding thin-film can harbor QAHE at\ntemperatures of 17-29 Kelvin, which is two orders of magnitude higher than the\ntypical temperatures in similar systems. Our proposed \\textit{nonmagnetic}\ndoping scheme may shed new light in experimental realization of\nhigh-temperature QAHE in topological insulators."
    },
    {
        "anchor": "Flexible Bacterial Cellulose Permalloy nanocomposite xerogel sheets size\n  scalable magnetic actuator cum electrical conductor: Permalloy nanoparticles containing bacterial cellulose hydrogel obtained\nafter reduction was compressed into a xerogel flexible sheet by hot pressing at\n60 C at different pressures. The permalloy nanoparticles with an ordered\nstructure have a bimodal size distribution centered around 25 nm and 190 nm.\nThe smaller nanoparticles are superparamagnetic while the larger particles are\nferromagnetic at room temperature. The sheets have a room temperature\nmagnetisation of 20 emu/g and a coercivity of 32 Oe. The electrical\nconductivity of the flexible sheets increases with hot pressing pressure from 7\nS/cm to 40 S/cm at room temperature.",
        "positive": "Layer-by-Layer assembling and characterizations of dye-polyions onto\n  solid substrate by Electrostatic adsorption process: Self assembled films of organic azobenzene dye chicago sky blue 6B (CSB) have\nbeen fabricated onto solid substarte by electrostatic alternate adsorption of\npolycation ploy(allyl amine hydrochloride) (PAH) and CSB. UV-Vis absorption\nspectroscopic studies reveal the successful incorporation of CSB molecules into\nLbL films and consequent formation of aggregates. This view is supported by\nFTIR spectroscopic studies. Scanning electron microscope picture confirms the\nformation of nano crystalline aggregates in the LbL films. About 15 minute is\nrequired to complete the electrostatic interaction between PAH and CSB\nmolecules in one bi-layer LbL film."
    },
    {
        "anchor": "Diameter-dependent conductance oscillations in carbon nanotubes upon\n  torsion: We combine electromechanical measurements with {\\em ab initio} density\nfunctional calculations to settle the controversy about the origin of\ntorsion-induced conductance oscillations in multi-wall carbon nanotubes.\nAccording to our observations, the oscillation period is inversely proportional\nto the squared diameter of the nanotube, as expected for a single-wall nanotube\nof the same diameter. This is supported by our theoretical finding that\ndifferential torsion effectively decouples the walls of a multi-wall nanotube\nnear the Fermi level and moves the Fermi momentum across quantization lines. We\nexclude the alternative explanation linked to registry changes between the\nwalls, since it would cause a different diameter dependence of the oscillation\nperiod.",
        "positive": "Bistability of vortex core dynamics in a single perpendicularly\n  magnetized nano-disk: Microwave spectroscopy of individual vortex-state magnetic nano-disks in a\nperpendicular bias magnetic field, $H$, is performed using a magnetic resonance\nforce microscope (MRFM). It reveals the splitting induced by $H$ on the\ngyrotropic frequency of the vortex core rotation related to the existence of\nthe two stable polarities of the core. This splitting enables spectroscopic\ndetection of the core polarity. The bistability extends up to a large negative\n(antiparallel to the core) value of the bias magnetic field $H_r$, at which the\ncore polarity is reversed. The difference between the frequencies of the two\nstable rotational modes corresponding to each core polarity is proportional to\n$H$ and to the ratio of the disk thickness to its radius. Simple analytic\ntheory in combination with micromagnetic simulations give quantitative\ndescription of the observed bistable dynamics."
    },
    {
        "anchor": "Room-Temperature Anisotropic Plasma Mirror and Polarization-Controlled\n  Optical Switch Based on Type-II Weyl Semimetal WP2: Anisotropy in electronic structures may ignite intriguing anisotropic optical\nresponses, as has been well demonstrated in various systems including\nsuperconductors, semiconductors, and even topological Weyl semimetals.\nMeanwhile, it is well established in metal optics that the metal reflectance\ndeclines from one to zero when the photon frequency is above the plasma\nfrequency {\\omega}p , behaving as a plasma mirror. However, the exploration of\nanisotropic plasma mirrors and corresponding applications remains elusive,\nespecially at room temperature. Here, we discover a pronounced anisotropic\nplasma reflectance edge in the type-II Weyl semimetal WP2, with an anisotropy\nratio of {\\omega}p up to 1.5. Such anisotropic plasma mirror behavior and its\nrobustness against temperature promise optical device applications over a wide\ntemperature range. For example, the high sensitivity of polarization-resolved\nplasma reflectance edge renders WP2 an inherent polarization detector. We\nfurther achieve a room-temperature WP2-based optical switch, effectively\ncontrolled by simply tuning the light polarization. These findings extend the\nfrontiers of metal optics as a discipline and promise the design of\nmultifunctional devices combining both topological and optical features.",
        "positive": "Nanocavity-mediated Purcell enhancement of Er in TiO$_2$ thin films\n  grown via atomic layer deposition: The use of trivalent erbium (Er$^{3+}$), typically embedded as an atomic\ndefect in the solid-state, has widespread adoption as a dopant in\ntelecommunications devices and shows promise as a spin-based quantum memory for\nquantum communication. In particular, its natural telecom C-band optical\ntransition and spin-photon interface makes it an ideal candidate for\nintegration into existing optical fiber networks without the need for quantum\nfrequency conversion. However, successful scaling requires a host material with\nfew intrinsic nuclear spins, compatibility with semiconductor foundry\nprocesses, and straightforward integration with silicon photonics. Here, we\npresent Er-doped titanium dioxide (TiO$_2$) thin film growth on silicon\nsubstrates using a foundry-scalable atomic layer deposition process with a wide\nrange of doping control over the Er concentration. Even though the as-grown\nfilms are amorphous, after oxygen annealing they exhibit relatively large\ncrystalline grains, and the embedded Er ions exhibit the characteristic optical\nemission spectrum from anatase TiO$_2$. Critically, this growth and annealing\nprocess maintains the low surface roughness required for nanophotonic\nintegration. Finally, we interface Er ensembles with high quality factor Si\nnanophotonic cavities via evanescent coupling and demonstrate a large Purcell\nenhancement (300) of their optical lifetime. Our findings demonstrate a\nlow-temperature, non-destructive, and substrate-independent process for\nintegrating Er-doped materials with silicon photonics. At high doping densities\nthis platform can enable integrated photonic components such as on-chip\namplifiers and lasers, while dilute concentrations can realize single ion\nquantum memories."
    },
    {
        "anchor": "Electron corrected Lorentz forces in solids and molecules in magnetic\n  field: We describe the effective Lorentz forces on the ions of a generic insulating\nsystem in an magnetic field, in the context of Born-Oppenheimer ab-initio\nmolecular dynamics. The force on each ion includes an important contribution of\nelectronic origin, which depends explicitly on the velocity of all other ions.\nIt is formulated in terms of a Berry curvature, in a form directly suitable for\nfuture first principles classical dynamics simulations based {\\it e.g.,} on\ndensity functional methods. As a preliminary analytical demonstration we\npresent the dynamics of an H$_2$ molecule in a field of intermediate strength,\napproximately describing the electrons through Slater's variational\nwavefunction.",
        "positive": "Geometric, electronic, and magnetic structure of Co$_2$FeSi: Curie\n  temperature and magnetic moment measurements and calculations: In this work a simple concept was used for a systematic search for new\nmaterials with high spin polarization. It is based on two semi-empirical\nmodels. Firstly, the Slater-Pauling rule was used for estimation of the\nmagnetic moment. This model is well supported by electronic structure\ncalculations. The second model was found particularly for Co$_2$ based Heusler\ncompounds when comparing their magnetic properties. It turned out that these\ncompounds exhibit seemingly a linear dependence of the Curie temperature as\nfunction of the magnetic moment. Stimulated by these models, Co$_2$FeSi was\nrevisited. The compound was investigated in detail concerning its geometrical\nand magnetic structure by means of X-ray diffraction, X-ray absorption and\nM\\\"o\\ss bauer spectroscopies as well as high and low temperature magnetometry.\nThe measurements revealed that it is, currently, the material with the highest\nmagnetic moment ($6\\mu_B$) and Curie-temperature (1100K) in the classes of\nHeusler compounds as well as half-metallic ferromagnets. The experimental\nfindings are supported by detailed electronic structure calculations."
    },
    {
        "anchor": "Domain wall roughness and creep in nanoscale crystalline ferroelectric\n  polymers: We report piezo-response force microscopy studies of the static and dynamic\nproperties of domain walls (DWs) in 11 to 36 nm thick films of crystalline\nferroelectric poly(vinylidene-fluoride-trifluorethylene). The DW roughness\nexponent {\\zeta} ranges from 0.39 to 0.48 and the DW creep exponent {\\mu}\nvaries from 0.20 to 0.28, revealing an unexpected effective dimensionality of\n~1.5 that is independent of film thickness. Our results suggest predominantly\n2D ferroelectricity in the layered polymer and we attribute the fractal\ndimensionality to DW deroughening due to the correlations between the in-plane\nand out-of-plane polarization, an effect that can be exploited to achieve high\nlateral domain density for developing nanoscale ferroelectrics-based\napplications.",
        "positive": "Nonlinear Nonreciprocal Photocurrents under Phonon Dressing: Nonlinear optical (NLO) effects have attracted great interest recently.\nHowever, by far the computational studies on NLO use the independent particle\napproximation and ignore many-body effects. Here we develop a generic Green's\nfunction framework to calculate the NLO response functions, which can\nincorporate various many-body interactions. We focus on the electron-phonon\ncoupling and reveal that phonon dressing can make significant impacts on\nnonlinear photocurrent, such as the bulk photovoltaic (BPV) and bulk spin\nphotovoltaic (BSPV) currents. BPV/BSPV should be zero for centrosymmetric\ncrystals, but when phonons are driven out-of-equilibrium, by for example, a\ntemperature gradient $\\nabla T$, the optical selections rules are altered and\nphonon-pumped BPV/BSPV currents can be non-zero in nominally centrosymmetric\ncrystal. Moreover, we elucidate that such NLO responses under non-equilibrium\nphonon dressing can be nonreciprocal, as the direction of the current does not\nnecessarily get reversed when the direction of the temperature gradient is\nreversed."
    },
    {
        "anchor": "Potential improvement for elastocaloric performances of shape memory\n  alloys through comparing with natural rubber: The elastocaloric (eC) effects of natural rubber (NR) and shape memory alloys\n(SMAs) are compared and potential improvement for eC performances of SMAs is\nproposed. Both the plateau and hysteresis of stress-strain curve in NR and SMAs\nare observed. They are attributed to the similar phase transformation:\nstrain-induced crystallization (SIC) in NR and martensitic transformation in\nSMAs. For NR, the drawback of large strain can be reduced by pre-strain. For\nSMAs, the stress change with strain is smaller in stress plateau regime. Thus,\nthe drawback of large dynamic stress of SMAs is proposed to be reduced by a\nstatic pre-stress for working directly in this stress plateau regime. Choosing\nan appropriate pre-strain (pre-stress) and strain amplitude can make eC effect\nof NR working in the phase transformation (SIC) regime. This method can improve\nboth the eC strength and fatigue life in NR. Due to the similar phase\ntransformation (martensitic transformation) of SMAs to NR, this method is also\nproposed to improve the eC performances of SMAs.",
        "positive": "Fermi surface determination from momentum density projections: The problem of determining a metal's Fermi surface from measurements of\nprojections of the electron or electron/positron momentum densities, such as\nobtained by Compton Scattering or Angular Correlation of Positron Annihilation\nRadiation, respectively, is considered in a Bayesian formulation. A consistent\napproach is presented and its advantages compared to previous practice is\ndiscussed. A validation of the proposed method on simulated data shows its\nsystematic accuracy to be very satisfactory and its statistical precision on\nmodest experimental data to be surprisingly good."
    },
    {
        "anchor": "Non-Resonant Thermal Admittance Spectroscopy: Thermal Admittance Spectroscopy (TAS) as become a popular technique to\ndetermine trap state density and energetic position in semiconductors. In the\nlimit of a large number of trap states ($>10^{16} \\text{cm}^{-3}$), Fermi-level\npinning undermines the assumptions used in the analysis of TAS data, which\nleads to a significant underestimation of the trap state density. Here, we\ndevelop the tools to detect and account for the occurrence of Fermi-level\npinning in TAS measurements.",
        "positive": "Object Kinetic Monte Carlo Simulations of Radiation Damage in Bulk\n  Tungsten Part-II: With a PKA Spectrum Corresponding to 14-MeV Neutrons: Object kinetic Monte Carlo was employed to study the effect of dose rate on\nthe evolution of vacancy microstructure in polycrystalline tungsten under\nneutron bombardment. The evolution was followed up to 1.0 displacement per atom\n(dpa) with point defects generated in accordance with a primary knock-on atom\n(PKA) spectrum corresponding to 14-MeV neutrons. The present study includes the\neffect of grain size (2.0 and 4.0 $\\mu$m) but excludes the impact of\ntransmutation or pre-existing defects beyond grain boundary sinks. Vacancy\ncluster density increases with dose rate, while the density of vacancies\ndecreases. Consequently, the average vacancy cluster size and the fraction of\nvacancies in visible clusters decrease with increasing dose rate. The density\nof vacancies and vacancy clusters decrease with grain size such that the\naverage size of the clusters remains similar. However, the average size is\nlarger for larger grains at dose rates < 4.5 x 10-7 dpa/s. The trend of vacancy\naccumulation as a function of dose, dose rate, and grain size is similar to\nthat obtained with the High Flux Isotope Reactor (HFIR) PKA spectrum. However,\nthe amount of vacancy accumulation and the vacancy microstructure are quite\ndifferent. Compared to the HFIR case, we find that even though the dose rates\nare 2.5 times higher, the density of vacancies and the average vacancy cluster\nsizes are lower. In addition, a void lattice forms only for the lowest two dose\nrates (4.5 x 10-8 and 4.5 x 10-9 dpa/s). In contrast, a void lattice formed at\nall dose rates studied using the HFIR PKA spectrum. We discuss in detail the\nfactors that lead to these different microstructures."
    },
    {
        "anchor": "Calculation of the current noise spectrum in mesoscopic transport: an\n  efficient quantum master equation approach: Based on our recent work on quantum transport [Li et al., Phys. Rev. B 71,\n205304 (2005)], where the calculation of transport current by means of quantum\nmaster equation was presented, in this paper we show how an efficient\ncalculation can be performed for the transport noise spectrum. Compared to the\nlongstanding classical rate equation or the recently proposed quantum\ntrajectory method, the approach presented in this paper combines their\nrespective advantages, i.e., it enables us to tackle both the many-body Coulomb\ninteractionand quantum coherence on equal footing and under a wide range of\nsetup circumstances. The practical performance and advantages are illustrated\nby a number of examples, where besides the known results and new insights\nobtained in a transparent manner, we find that this alternative approach is\nmuch simpler than other well-known full quantum mechanical methods such as the\nLandauer-B\\\"uttiker scattering matrix theory and the nonequilibrium Green's\nfunction technique.",
        "positive": "Nanofabrication of spin-transfer torque devices by a PMMA mask one step\n  process: GMR versus single layer devices: We present a method to prepare magnetic spin torque devices of low specific\nresistance in a one step lithography process. The quality of the pillar devices\nis demonstrated for a standard magnetic double layer device. For single layer\ndevices, we found hysteretic switching and a more complex dynamical excitation\npattern in higher fields. A simple model to explain the resistance spikes is\npresented."
    },
    {
        "anchor": "Laser-induced torques in metallic ferromagnets: We study laser-induced torques in bcc Fe, hcp Co and $L1_0$ FePt based on\nfirst-principles electronic structure calculations and the Keldysh\nnonequilibrium formalism. We find that the torques have two contributions, one\nfrom the inverse Faraday effect (IFE) and one from the optical spin-transfer\ntorque (OSTT). Depending on the ferromagnet at hand and on the quasiparticle\nbroadening the two contributions may be of similar magnitude or one\ncontribution may dominate over the other. Additionally, we determine the\nnonequilibrium spin polarization in order to investigate its relation to the\ntorque. We find the torques and the perpendicular component of the\nnonequilibrium spin polarization to be odd in the helicity of the laser light,\nwhile the spin polarization that is induced parallel to the magnetization is\nhelicity-independent. The parallel component of the nonequilibrium spin\npolarization is orders of magnitude larger than the perpendicular component. In\nthe case of hcp Co we find good agreement between the calculated laser-induced\ntorque and a recent experiment.",
        "positive": "Designing Artificial Two-Dimensional Landscapes via Room-Temperature\n  Atomic-Layer Substitution: Manipulating materials with atomic-scale precision is essential for the\ndevelopment of next-generation material design toolbox. Tremendous efforts have\nbeen made to advance the compositional, structural, and spatial accuracy of\nmaterial deposition and patterning. The family of 2D materials provides an\nideal platform to realize atomic-level material architectures. The wide and\nrich physics of these materials have led to fabrication of heterostructures,\nsuperlattices, and twisted structures with breakthrough discoveries and\napplications. Here, we report a novel atomic-scale material design tool that\nselectively breaks and forms chemical bonds of 2D materials at room\ntemperature, called atomic-layer substitution (ALS), through which we can\nsubstitute the top layer chalcogen atoms within the 3-atom-thick\ntransition-metal dichalcogenides using arbitrary patterns. Flipping the layer\nvia transfer allows us to perform the same procedure on the other side,\nyielding programmable in-plane multi-heterostructures with different\nout-of-plane crystal symmetry and electric polarization. First-principle\ncalculations elucidate how the ALS process is overall exothermic in energy and\nonly has a small reaction barrier, facilitating the reaction to occur at room\ntemperature. Optical characterizations confirm the fidelity of this design\napproach, while TEM shows the direct evidence of Janus structure and suggests\nthe atomic transition at the interface of designed heterostructure. Finally,\ntransport and Kelvin probe measurements on MoXY (X,Y=S,Se; X and Y\ncorresponding to the bottom and top layers) lateral multi-heterostructures\nreveal the surface potential and dipole orientation of each region, and the\nbarrier height between them. Our approach for designing artificial 2D landscape\ndown to a single layer of atoms can lead to unique electronic, photonic and\nmechanical properties previously not found in nature."
    },
    {
        "anchor": "Quantum spin Hall effect in two-dimensional transition-metal\n  chalcogenides: Based on first-principles calculations, we have found a family of 2D\ntransition-metal (TM) chalcogenides MX5 (M = Zr, Hf and X = S, Se and Te) can\nhost quantum spin Hall (QSH) effect. The molecular dynamics simulation indicate\nthat they are all thermal-dynamically stable at room temperature, the largest\nband gap is 0.19 eV. We have investigated MX5's electronic properties and found\ntheir properties are very similar. The single-layer ZrX5 are all gapless\nsemimetals without consideration of spin-orbit coupling (SOC). The\nconsideration of SOC will result in insulating phases with band gaps of 0.05 eV\n(direct), 0.18 eV (direct) and 0.13 eV (indirect) for ZrS5, ZrSe5 to ZrTe5,\nrespectively. The evolution of Wannier charge centers and edge states confirm\nthey are all QSH insulators. The mechanisms for QSH effect in ZrX5 originate\nfrom the special nonsymmorphic space group features. In addition, the QSH state\nof ZrS5 survives at a large range of strain as long as the interchain coupling\nis not strong enough to reverse the band ordering. The single-layer ZrS5 will\noccur a topological insulator (TI)-to-semimetal (metal) or metal-to-semimetal\ntransition under certain strain. Monolayer MX5 expand the TI materials based on\nTM chalcogenides and may open up a new way to fabricate novel low power\nspintronic devices at room temperature.",
        "positive": "Boosting the efficiency of ab initio electron-phonon coupling\n  calculations through dual interpolation: The coupling between electrons and phonons in solids plays a central role in\ndescribing many phenomena, including superconductivity and thermoelecric\ntransport. Calculations of this coupling are exceedingly demanding as they\nnecessitate integrations over both the electron and phonon momenta, both of\nwhich span the Brillouin zone of the crystal, independently. We present here an\nab initio method for efficiently calculating electron-phonon mediated transport\nproperties by dramatically accelerating the computation of the double integrals\nwith a dual interpolation technique that combines maximally localized Wannier\nfunctions with symmetry-adapted plane waves. The performance gain in relation\nto the current state-of-the-art Wannier-Fourier interpolation is approximately\n2n_s \\times M, where n_s is the number of crystal symmetry operations and M, a\nnumber in the range 5 - 60, governs the expansion in star functions. We\ndemonstrate with several examples how our method performs some ab initio\ncalculations involving electron-phonon interactions."
    },
    {
        "anchor": "Layer-dependent Optical and Dielectric Properties of Large-size PdSe$_2$\n  Films Grown by Chemical Vapor Deposition: Palladium diselenide (PdSe$_2$), a new type of two-dimensional noble metal\ndihalides (NMDCs), has received widespread attention for its excellent\nelectrical and optoelectronic properties. Herein, high-quality continuous\ncentimeter-scale PdSe$_2$ films with layers in the range of 3L-15L were grown\nusing Chemical Vapor Deposition (CVD) method. The absorption spectra and DFT\ncalculations revealed that the bandgap of the PdSe$_2$ films decreased with\nincreasing number of layers, which is due to PdSe$_2$ enhancement of orbital\nhybridization. Spectroscopic ellipsometry (SE) analysis shows that PdSe2 has\nsignificant layer-dependent optical and dielectric properties. This is mainly\ndue to the unique strong exciton effect of the thin PdSe$_2$ film in the UV\nband. In particular, the effect of temperature on the optical properties of\nPdSe$_2$ films was also observed, and the thermo-optical coefficients of\nPdSe$_2$ films with different number of layers were calculated. This study\nprovides fundamental guidance for the fabrication and optimization of\nPdSe$_2$-based optoelectronic devices.",
        "positive": "Using the Callaway model to deduce relevant phonon scattering processes:\n  The importance of phonon dispersion: The thermal conductivity $\\kappa$ of a material is an important parameter in\nmany different applications. Optimization strategies of $\\kappa$ often require\ninsight into the dominant phonon scattering processes of the material under\nstudy. The Callaway model is widely used as an experimentalist's tool to\nanalyze the lattice part of the thermal conductivity, $\\kappa_l$. Here, we\ninvestigate how deviations from the implicitly assumed linear phonon dispersion\nrelation affect $\\kappa_l$ and in turn conclusions regarding the relevant\nphonon scattering processes. As an example, we show for the half-Heusler system\n(Hf,Zr,Ti)NiSn, that relying on the Callaway model in its simplest form has\nearlier resulted in a misinterpretation of experimental values by assigning the\nlow measured $\\kappa_l$ with unphysically strong phonon scattering in these\nmaterials. Instead, we propose an implementation of more realistic phonon\ndispersion curves, combined with empirical expressions for typical phonon\nscattering processes, which leads to far better quantitative agreement with\nboth theoretical and experimental values. This method can easily be extended to\nother materials with known phonon dispersion relations."
    },
    {
        "anchor": "Energy-momentum mapping of d-derived Au(111) states in a thin film: The quantum well states of a film can be used to sample the electronic\nstructure of the parent bulk material and determine its band parameters. We\nhighlight the benefits of two-dimensional film band mapping, with respect to\ncomplex bulk analysis, in an angle-resolved photoemission spectroscopy study of\nthe 5d states of Au(111). Discrete 5d-derived quantum well states of various\norbital characters form in Au(111) films and span the width of the\ncorresponding bulk bands. For sufficiently thick films, the dispersion of these\nstates samples the bulk band edges, as confirmed by first-principles\ncalculations, thus providing the positions of the critical points of bulk Au in\nagreement with previously determined values. In turn, this analysis identifies\nseveral d-like surface states and resonances with large spin-splittings that\noriginate from the strong spin-orbit coupling of the Au 5d atomic levels.",
        "positive": "First-principles calculation of magnetoelastic coefficients and\n  magnetostriction in the spinel ferrites CoFe2O4 and NiFe2O4: We present calculations of magnetostriction constants for the spinel ferrites\nCoFe2O4 and NiFe2O4 using density functional theory within the GGA+U approach.\nSpecial emphasis is devoted to the influence of different possible cation\ndistributions on the B site sublattice of the inverse spinel structure on the\ncalculated elastic and magnetoelastic constants. We show that the resulting\nsymmetry-lowering has only a negligible effect on the elastic constants of both\nsystems as well as on the magnetoelastic response of NiFe2O4, whereas the\nmagnetoelastic response of CoFe2O4 depends more strongly on the specific cation\narrangement. In all cases our calculated magnetostriction constants are in good\nagreement with available experimental data. Our work thus paves the way for\nmore detailed first-principles studies regarding the effect of stoichiometry\nand cation inversion on the magnetostrictive properties of spinel ferrites."
    },
    {
        "anchor": "Polarization-driven topological insulator transition in a GaN/InN/GaN\n  quantum well: Topological insulator (TI) states have been demonstrated in materials with\nnarrow gap and large spin-orbit interactions (SOI). Here we demonstrate that\nnanoscale engineering can also give rise to a TI state, even in conventional\nsemiconductors with sizable gap and small SOI. Based on advanced\nfirst-principles calculations combined with an effective low-energy k*p\nHamiltonian, we show that the intrinsic polarization of materials can be\nutilized to simultaneously reduce the energy gap and enhance the SOI, driving\nthe system to a TI state. The proposed system consists of ultrathin InN layers\nembedded into GaN, a layer structure that is experimentally achievable.",
        "positive": "Linear versus nonlinear electro-optic effects in materials: Two schemes are proposed to compute the nonlinear electro-optic (EO) tensor\nfor the first time. In the first scheme, we compute the linear EO tensor of the\nstructure under a finite electric field, while we compute the refractive index\nof the structure under a finite electric field in the second scheme. Such\nschemes are applied to Pb(Zr,Ti)O$_{3}$ and BaTiO$_{3}$ ferroelectric oxides.\nIt is found to reproduce a recently observed feature, namely why\nPb(Zr$_{0.52}$Ti$_{0.48}$)O$_{3}$ adopts a mostly linear EO response while\nBaTiO$_{3}$ exhibits a strongly nonlinear conversion between electric and\noptical properties. Furthermore, the atomistic insight provided by the proposed\nab-initio scheme reveals the origin of such qualitatively different responses,\nin terms of the field-induced behavior of the frequencies of some phonon modes\nand of some force constants."
    },
    {
        "anchor": "Elastic, thermodynamic, electronic and optical properties of U2Ti: An investigation of U2Ti, a potentially safe and heavy metal-based storage\nmaterial for radioactive tritium for fusion reactor, has been performed using\npseudopotential density functional theory. The analysis of the elastic\nconstants and other moduli calculated for the first time shows large anisotropy\non elasticity and brittle behavior. A quasi-harmonic Debye model, which\nconsiders the vibrational contribution to the total free energy of the system,\nhas been used to investigate the finite-temperature and finite-pressure\nthermodynamic properties of U2Ti. The electronic band structure reveals\nmetallic conductivity and the major contribution comes from U-5f states. By\nanalyzing the optical spectra, the origin of the various structures is also\nexplained in terms of the calculated electronic structure. Further the\nreflectivity spectrum shows that the material is perfect reflector within the\nenergy range 8-12.5 eV.\n  Keywords: Uranium-titanium alloy; First-principles calculations;\nQuasi-harmonic Debye model; Mechanical properties, Band structure, Optical\nproperties",
        "positive": "Phase Reconstruction of a Cu(001) Seed Layer from $\\textit{in situ}$\n  Polarized Neutron Reflectometry Data using Fe Reference Layers: The reconstruction of the complex reflection coefficient obtained by in situ\nPolarized Neutron Reflectometry is presented. Using the reference layer method,\nwith a magnetic Fe layer, the phase information of the underlying Cu(001) seed\nlayer sample structure is successfully retrieved and its scattering length\ndensity is calculated and compared with results obtained from traditional\nfitting. Two different reference layer approaches for retrieving the phase\ninformation are compared."
    },
    {
        "anchor": "Structural and physical properties of $SrMn_{1-x}Ru_xO_3$ perovskites: We combine the results of magnetic and transport measurements with neutron\ndiffraction data to construct the structural and magnetic phase diagram of the\nentire family of SrMn$_{1-x}$Ru$_{x}$O$_3$ ($0 \\leqslant x \\leqslant 1$)\nperovskites. We have found antiferromagnetic ordering of the C type for lightly\nRu-substituted materials ($0.06 \\leqslant x \\leqslant 0.5$) in a similar manner\nto $R_{y}$Sr$_{1-y}$MnO$_3$ ($R$=La, Pr), due to the generation of Mn$^{3+}$ in\nboth families of manganite perovskites by either $B$-site substitution of\nRu$^{5+}$ for Mn$^{4+}$ or $A$-site substitution of $R^{3+}$ for Sr$^{2+}$.\nThis similarity is driven by the same ratio of $d^4$ / $d^3$ ions in both\nclasses of materials for equivalent substitution level. In both cases, a\ntetragonal lattice distortion is observed, which for some compositions ($0.06\n\\leqslant x \\leqslant 0.2$) is coupled to a C-type AF transition and results in\na first order magnetic and resistive transition. Heavily substituted\nSrMn$_{1-x}$Ru$_{x}$O$_3$ materials are ferromagnetic due to dominating\nexchange interactions between the Ru$^{4+}$ ions. Intermediate substitution\n($0.6 \\leqslant x \\leqslant 0.7$) leads to a spin-glass behavior instead of a\nquantum critical point reported previously in single crystals, due to enhanced\ndisorder.",
        "positive": "Instability, Intermixing and Electronic Structure at the Epitaxial\n  LaAlO3/SrTiO3(001) Heterojunction: The question of stability against diffusional mixing at the prototypical\nLaAlO3/SrTiO3(001) interface is explored using a multi-faceted experimental and\ntheoretical approach. We combine analytical methods with a range of\nsensitivities to elemental concentrations and spatial separations to\ninvestigate interfaces grown using on-axis pulsed laser deposition. We also\nemploy computational modeling based on the density function theory as well as\nclassical force fields to explore the energetic stability of a wide variety of\nintermixed atomic configurations relative to the idealized, atomically abrupt\nmodel. Statistical analysis of the calculated energies for the various\nconfigurations is used to elucidate the relative thermodynamic stability of\nintermixed and abrupt configurations. We find that on both experimental and\ntheoretical fronts, the tendency toward intermixing is very strong. We have\nalso measured and calculated key electronic properties such as the presence of\nelectric fields and the value of the valence band discontinuity at the\ninterface. We find no measurable electric field in either the LaAlO3 or SrTiO3,\nand that the valence band offset is near zero, partitioning the band\ndiscontinuity almost entirely to the conduction band edge. Moreover, we find\nthat it is not possible to account for these electronic properties\ntheoretically without including extensive intermixing in our physical model of\nthe interface. The atomic configurations which give the greatest electrostatic\nstability are those that eliminate the interface dipole by intermixing, calling\ninto question the conventional explanation for conductivity at this interface -\nelectronic reconstruction. Rather, evidence is presented for La indiffusion and\ndoping of the SrTiO3 below the interface as being the cause of the observed\nconductivity."
    },
    {
        "anchor": "Electric-field modulation of exchange stiffness in MgO/CoFeB with\n  perpendicular anisotropy: We observe magnetic domain structures of MgO/CoFeB with a perpendicular\nmagnetic easy axis under an electric field. The domain structure shows a maze\npattern with electric-field dependent isotropic period. We find that the\nelectric-field modulation of the period is explained by considering the\nelectric-field modulation of the exchange stiffness constant in addition to the\nknown magnetic anisotropy modulation.",
        "positive": "Shot Noise in Linear Macroscopic Resistors: We report on a direct experimental evidence of shot noise in a linear\nmacroscopic resistor. The origin of the shot noise comes from the fluctuation\nof the total number of charge carriers inside the resistor associated with\ntheir diffusive motion under the condition that the dielectric relaxation time\nbecomes longer than the dynamic transit time. Present results show that neither\npotential barriers nor the absence of inelastic scattering are necessary to\nobserve shot noise in electronic devices."
    },
    {
        "anchor": "Van der Waals Density Functional for General Geometries: A scheme within density functional theory is proposed that provides a\npractical way to generalize to unrestricted geometries the method applied with\nsome success to layered geometries [H. Rydberg, et al., Phys. Rev. Lett. 91,\n126402 (2003)]. It includes van der Waals forces in a seamless fashion. By\nexpansion to second order in a carefully chosen quantity contained in the long\nrange part of the correlation functional, the nonlocal correlations are\nexpressed in terms of a density-density interaction formula. It contains a\nrelatively simple parametrized kernel, with parameters determined by the local\ndensity and its gradient. The proposed functional is applied to rare gas and\nbenzene dimers, where it is shown to give a realistic description.",
        "positive": "Superheated solid state induced by a single collision event: High-energy incident particles from both pulsed and continuous radiation\nsources can induce significant damage to the structure of a material by\ncreating vacancy-interstitial pairs and other more complex defects, and this\nleads typically to localized melting. In this work, we present evidence via\nmolecular dynamics simulations of a superheated solid state in BCC tungsten\ninduced by single PKA events of $\\sim$ 1.5 keV of energy. Despite the striking\ndifference between this highly inhomogeneous energy injection and homogeneous\nmelting, the lifetime of the obtained superheated solid state, reaching up to\n200 ps, is described through a waiting time distribution in agreement with\nprevious studies on superheating in the Z-method methodology."
    },
    {
        "anchor": "Thermally nucleated magnetic reversal in CoFeB/MgO nanodots: Power consumption is the main limitation in the development of new high\nperformance random access memory for portable electronic devices. Magnetic RAM\n(MRAM) with CoFeB/MgO based magnetic tunnel junctions (MTJs) is a promising\ncandidate for reducing the power consumption given its non-volatile nature\nwhile achieveing high performance. The dynamic properties and switching\nmechanisms of MTJs are critical to understanding device operation and to enable\nscaling of devices below 30 nm in diameter. Here we show that the magnetic\nreversal mechanism is incoherent and that the switching is thermally nucleated\nat device operating temperatures. Moreover, we find an intrinsic thermal\nswitching field distribution arising on the sub-nanosecond timescale even in\nthe absence of size and anisotropy distributions or material defects. These\nfeatures represent the characteristic signature of the dynamic properties in\nMTJs and give an intrinsic limit to reversal reliability in small magnetic\nnanodevices.",
        "positive": "Study of Magnetic Excitation in Singlet-Ground-State Magnets CsFeCl$_3$\n  and RbFeCl$_3$ by Nuclear Magnetic Relaxation: The temperature dependences of spin-lattice relaxation time $T_1$ of\n$^{133}$Cs in CsFeCl$_3$ and $^{87}$Rb in RbFeCl$_3$ were measured in the\ntemperature range between 1.5 K and 22 K, at various fields up to 7 T applied\nparallel (or perpendicular) to the c-axis, and the analysis was made on the\nbasis of the DCEFA. The mechanism of the nuclear magnetic relaxation is\ninterpreted in terms of the magnetic fluctuations which are characterized by\nthe singlet ground state system. In the field region where the phase transition\noccurs, $T_1^{-1}$ exhibited the tendency of divergence near $T_{\\rm N}$, and\nthis feature was ascribed to the transverse spin fluctuation associated with\nthe mode softening at the $K$-point. It was found that the damping constant of\nthe soft mode is remarkably affected by the occurrence of the magnetic ordering\nat lower temperature, and increases largely in the field region where the phase\ntransition occurs."
    },
    {
        "anchor": "An Invertible Seven-Dimensional Dirichlet Cell Characterization of\n  Lattices: Characterization of crystallographic lattices is an important tool in\nstructure solution, crystallographic database searches and clustering of\ndiffraction images in serial crystallography. Characterization of lattices by\nNiggli-reduced cells (based on the three shortest non-coplanar lattice edge\nvectors) or by Delaunay-reduced cells (based on four edge vectors summing to\nzero and all meeting at obtuse or right angles) are commonly used. The Niggli\ncell derives from Minkowski reduction. The Delaunay cell derives from Selling\nreduction. All are related to the Wigner-Seitz (or Dirichlet, or Voronoi) cell\nof the lattice, which consists of the points at least as close to a chosen\nlattice point than they are to any other lattice point. Starting from a\nNiggli-reduced cell, the Dirichlet cell is characterized by the planes\ndetermined by thirteen lattice half-edges: the midpoints of the three Niggli\ncell edges, the six Niggli cell face diagonals and the four body-diagonals, but\nseven of the edge lengths are sufficient: three edge lengths, the three shorter\nof each pair of face-diagonal lengths and the shortest body-diagonal length,\nfrom which the Niggli-reduced cell may be recovered.",
        "positive": "Treatment of electron viscosity in quantum conductance: In a recent paper Sai {\\it et al.} [1] identified a correction $R^{dyn}$ to\nthe DC conductance of nanoscale junctions arising from dynamical\nexchange-correlation ($XC$) effects within time-dependent density functional\ntheory. This quantity contributes to the total resistance through\n$R=R_{s}+R^{dyn}$ where $R_{s}$ is the resistance evaluated in the absence of\ndynamical $XC$ effects. In this Comment we show that the numerical estimation\nof $R^{dyn}$ in example systems of the type they considered should be\nconsiderably reduced, once a more appropriate form for the shear electron\nviscosity $\\eta$ is used."
    },
    {
        "anchor": "The structure of amorphous, crystalline and liquid GeO2: Germanium dioxide ($GeO_2$) is a chemical analogue of $SiO_2$. Furthermore,\nit is also to some extent a structural analogue, as the low and high-pressure\nshort-range order (tetrahedral and octahedral) is the same. However, a number\nof differences exist. For example, the $GeO_2$ phase diagram exhibits a smaller\nnumber of polymorphs, and all three $GeO_2$ phases (crystalline, glass, liquid)\nhave an increased sensitivity to pressure, undergoing pressure induced changes\nat much lower pressures than their equivalent $SiO_2$ analogues. In addition,\ndifferences exist in $GeO_2$ glass in the medium range order, resulting in the\nglass transition temperature of germania being much lower than for silica. This\nreview highlights the structure of amorphous $GeO_2$ by different experimental\n(e.g., Raman and NMR spectroscopy, neutron and x-ray diffraction) and\ntheoretical methods (e.g., classical molecular dynamics, ab initio\ncalculations). It also addresses the structure of liquid and crystalline\n$GeO_2$ that have received much less attention. Furthermore, we compare and\ncontrast the structural differences between $GeO_2$ and $SiO_2$, as well as,\nalong the $GeO_2-SiO_2$ join. It is probably a very timely review as interest\nin this compound, that can be investigated in the liquid state at relatively\nlow temperatures and pressures, continues to increase.",
        "positive": "Steady-state photoconductivity and multi-particle interactions in\n  rubrene single crystals: We demonstrate that photoconductivity of pristine rubrene crystals exhibits\nseveral distinct regimes, in which photocurrent as a function of cw (continuous\nwave) excitation intensity is described by a power law with exponents\nsequentially taking values 1, 1/3 and 1/4. We show that this photocurrent is\ngenerated almost exclusively at the surface of pristine rubrene crystals, while\nthe bulk photocurrent is dramatically smaller and follows a different set of\nexponents, 1 and 1/2. A model based on exciton fission, fusion and\ntriplet-charge quenching is developed to describe these non-trivial effects in\nphotoconductivity of highly ordered organic semiconductors."
    },
    {
        "anchor": "Studies of Multiferroic System LiCu2O2 I Sample Characterization and\n  Relationship between Magnetic Properties and Multiferroic Nature: Single-crystal samples of LiCu2O2 with spin 1/2 Cu2+ chains of edge-sharing\nCuO4 square planes (ribbon chains), have been characterized by X-ray\ndiffraction, thermogravimetric analysis, and magnetic measurements. Neither the\natomic deficiency nor the mixing of Cu and Li atoms has been found, indicating\nthat lattice defects conceived as a possible origin of the reported\nmultiferroic behavior can be excluded. Anomalies found in the data of specific\nheat and neutron magnetic Bragg reflections show clear evidence that the system\nexhibits successive magnetic transitions at TN1=24.5 K and TN2=22.8 K. Based on\nthe magnetic structures in the intermediate (TN2<T<TN1) and low temperature\n(T<TN2) phases, determined by the combined studies of neutron scattering and\n7Li-NMR measurements, we can consistently understand the fact that the\nmultiferroic properties are observed only below TN2 by considering existing\ntheories.",
        "positive": "Approaches to modelling irradiation-induced processes in transmission\n  electron microscopy: The recent progress in high-resolution transmission electron microscopy\n(HRTEM) has given rise to the possibility of in situ observations of\nnanostructure transformations and chemical reactions induced by electron\nirradiation. In this article we briefly summarise experimental observations and\ndiscuss in detail atomistic modelling of irradiation-induced processes in\nHRTEM, as well as mechanisms of such processes recognised due to modelling.\nAccurate molecular dynamics (MD) techniques based on first principles or\ntight-binding models are employed in the analysis of single irradiation-induced\nevents, and classical MD simulations are combined with a kinetic Monte Carlo\nalgorithm to simulate continuous irradiation of nanomaterials. It has been\nshown that sulphur-terminated graphene nanoribbons are formed inside carbon\nnanotubes as a result of an irradiation-selective chemical reaction. The\nprocess of fullerene formation in HRTEM during continuous electron irradiation\nof a small graphene flake has been simulated, and mechanisms driving this\ntransformation analysed."
    },
    {
        "anchor": "Comprehensive understanding of water-driven graphene wrinkle life-cycle\n  towards applications in flexible electronics: A computational study: The presence of wrinkles in Graphene Nanoribbons (GNR) and other\ntwo-dimensional (2D) materials significantly alter their mechanical,\nelectronic, optical properties, which can be either beneficial or detrimental.\nExperimentally, it has been observed that during the commonly used growth\nprocess of GNR, water molecules, sourced from ambient humidity, can be diffused\nin between GNR and the substrate. The water diffusion causes wrinkle formation\nin GNR, which influences its properties. Furthermore, the diffused water\neventually dries, creating the alteration not only in the geometry of Wrinkled\nGraphene Nanoribbons (WGNR) but also its features. Computational analysis of\nthese phenomena can provide an atomistic-level understanding of the phenomena.\nTherefore, in this work, Molecular Dynamics (MD) simulations are performed to\nmodel the water diffusion and evaporation in between GNR and its substrate, and\ntheir effect on wrinkle formation and dynamics. Additionally, Density\nFunctional Theory (DFT)-based analysis is used to characterize the difference\nin the electronic structure of WGNR caused by the change in wrinkle geometry.\nOur study reveals that the initially distributed wrinkles tend to coalesce to\nform a localized wrinkle whose configuration depends on the initial wrinkle\ngeometry and the amount of diffused water. The wrinkle configuration changes\nupon drying, while it remains static until the complete drying. The movement of\nthe localized wrinkle is the combination of three fundamental modes - bending,\nbuckling, and sliding. The stress analysis reveals that the maximum stress is\nat the base of the wrinkle, and its magnitude is always below the plasticity\nlimit. The DFT results provide insight into the potential of using the wrinkles\nto control the direction of electron flow for the applications in flexible\nelectronics.",
        "positive": "Electronic energy loss processes for slow H and He ions in metals and\n  insulators: new insights: Electronic stopping of H and He ions in metals and insulators is analyzed at\nvelocities below 0.2 atomic units, i.e. below 1 keV for H and below 4 keV for\nHe. In metals, stopping of H ions is affected by d-electrons only when the\nd-band extends up to the Fermi energy; for He ions, also d-bands well below the\nFermi energy contribute significantly to electronic stopping. In insulators,\nthe low threshold velocity for electronic stopping cannot be explained by\nelectron-hole pair excitation; charge exchange cycles, however, may govern the\nthreshold behavior of electronic stopping in ionic crystals."
    },
    {
        "anchor": "A Local Concentration-based Descriptor Predicting the Stacking Fault\n  Energy of Refractory High Entropy Alloys: Stacking fault energy (SFE) is an essential parameter for characterizing\nmechanical properties. However, in high entropy alloys (HEAs), the local\nchemical environment varies significantly across different stacking fault\nplanes, resulting in a substantial fluctuation of SFE values rather than a\nunique value, which prohibits the prediction of the local SFE. Herein, we\nproposed an effective descriptor based on the local concentration ratio near\nstacking fault to quantitatively predict the local SFE of refractory HEAs. We\nfind that the role of a given element in determining SFE strongly depends on\nits valence-electron number relative to other components and the contribution\nof its s- and d-electrons to its cohesive properties, which can be understood\nin the framework of the tight-binding model. Notably, the descriptor not only\nunifies the local nature of SFE from simple alloys to HEAs but also helps to\nquickly design HEAs as the involved parameters are easily accessible.",
        "positive": "Structural disorder and antiferromagnetism in LaNi1-xPtxO3: We report on the B-site substitution of Pt in the system LaNi1-xPtxO3. The\nsystem can only be synthesized for x <= 0.50, with LaNiO3 (x = 0.00) and the\nstoichiometric double perovskite La2NiPtO6 (x = 0.50) as the end members.\nHigher Pt-contents (x > 0.50) are unachievable due to the preference of Pt to\neither be in oxidation state +IV in octahedral coordination. Upon introducing\nPt into LaNiO3, a phase transformation from rhombohedral (R-3c) to monoclinic\n(P21/n) symmetry is observed for 0.075 <= x <= 0.125, where all monoclinic\nsamples are B-site ordered, and Pt show a strong preference for the Pt-site.\nPowder X-ray diffraction analysis reveal disorder of the Pt-distribution in\nseveral of the samples with a non-equimolar Ni/Pt ratio (0.20 <= x <= 0.40),\nwhich point toward cluster formation with domains of high and low Pt-content\nwithin each sample. La2NiPtO6 further show an antiferromagnetic transition at\napprox. 40 K. A similar transition is observed for all monoclinic samples (x >=\n0.20), however, the transition becomes weaker for lower x. This is explained in\nlight of the structural disorder, i.e. by the coexistence of antiferromagnetic\ndomains with long range order and paramagnetic domains dominated by short range\nantiferromagnetic interactions."
    },
    {
        "anchor": "Theoretical evidence for the semi-insulating character of AlN: We present ab initio density-functional calculations for acceptors, donors,\nand native defects in aluminum nitride, showing that acceptors are deeper (Be ~\n0.25 eV, Mg_ 0.45 eV) and less soluble than in GaN; at further variance with\nGaN, both the extrinsic donors Si_Al and C_Al, and the native donor V_N (the\nanion vacancy) are found to be deep (about 1 to 3 eV below the conduction). We\nthus predict that doped AlN will generally turn out to be semi-insulating in\nthe normally achieved Al-rich conditions, in agreement with the known doping\ndifficulties of high-x AlGaN alloys.",
        "positive": "Impact of oxygen ordering on titanium lattice parameters: Variations with oxygen concentration of titanium lattice parameters are\nobtained by means of ab initio calculations, considering the impact of oxygen\nordering. The quasiharmonic approximation is used to take into account the\nthermal expansion at finite temperature. Results show that lattice parameters\ndepend mainly on oxygen concentration and, to a lesser extent, on the ordering\nstate. Knowing these theoretical variations, one can get insights into the\ncomposition of ordered compounds existing in Ti-O binary alloys from their\nlattice mismatch measured experimentally by x-ray diffraction. The approach is\nused in a binary alloy containing 6000 ppm in weight of oxygen. It is concluded\nthat the ordered compounds, which are observed after a recrystallization heat\ntreatment, do not have the expected Ti6O stoichiometry but have a composition\nclose to the nominal concentration. Oxygen ordering proceeds, therefore, before\noxygen partitioning in titanium."
    },
    {
        "anchor": "Effective Scattering Cross-section in Lattice Thermal Conductivity\n  Calculation with Differential Effective Medium Method: To further reduce the lattice thermal conductivity of thermoelectric\nmaterials, the technique of embedding nano-inclusions into bulk matrix\nmaterials, in addition to point defect scattering via alloying, was widely\napplied. Differential Effective Medium (DEM) method was employed to calculate\ntwo-phase heterogeneous systems. However, in most effective medium treatment,\nthe interface scattering of matrix phonons by embedded nanoparticle was\nunderestimated by adopting particle's projected area as scattering\ncross-section. Herein, modified cross-section calculations, as well as grain\nsizes dispersions, are applied in DEM, with the calculations then validated by\ncomparing with Monte-Carlo simulations and existing experimental data.\nPredictions of lattice thermal conductivity reduction on in-situ formed Full\nHeusler(FH)/Half Heusler(HH) nano/matrix system are discussed.",
        "positive": "Magnetic structures of $\u03b4$-O$_2$ resulting from competition of\n  interplane exchange interactions: Solid oxygen is a unique molecular crystal whose phase diagram is mostly\nimposed by magnetic ordering, i.e., each crystal phase has a specific magnetic\nstructure. However, recent experiments showed that high-pressure $\\delta$-phase\nis implemented in different magnetic structures. In the present paper we study\nthe role of interplane exchange interactions in formation of the magnetic\nstructures with different stacking sequences of the close-packed planes. We\nshow that temperature-induced variation of intermolecular distances can give\nrise to compensation of the exchange coupling between the nearest close-packed\nplanes and result in the phase transition between different magnetic structures\nwithin $\\delta$-O$_2$. Variation of the magnetic ordering is, in turn,\naccompanied by the step-wise variation of interplane distance governed by space\nand angular dependence of interplane exchange constants."
    },
    {
        "anchor": "Gold on graphene as a substrate for surface enhanced Raman scattering\n  study: In this paper, we report our study on gold (Au) films with different\nthicknesses deposited on single layer graphene (SLG) as surface enhanced Raman\nscattering (SERS) substrates for the characterization of rhodamine (R6G)\nmolecules. We find that an Au film with a thickness of ~7 nm deposited on SLG\nis an ideal substrate for SERS, giving the strongest Raman signals for the\nmolecules and the weakest photoluminescence (PL) background. While Au films\neffectively enhance both the Raman and PL signals of molecules, SLG effectively\nquenches the PL signals from the Au film and molecules. The former is due to\nthe electromagnetic mechanism involved while the latter is due to the strong\nresonance energy transfer from Au to SLG. Hence, the combination of Au films\nand SLG can be widely used in the characterization of low concentration\nmolecules with relatively weak Raman signals.",
        "positive": "Atomically straight steps on vicinal Si (111) surfaces prepared by\n  step-parallel current in the kink-up direction: We demonstrate that annealing of a vicinal Si(111) surface at about 800 C\nwith a direct current in the direction that ascends the kinks enhances the\nformation of atomically straight step edges over micrometer lengths, while\nannealing with a current in the opposite direction does not. Every straight\nstep edge has the same atomic configuration U(2,0), which is useful as a\ntemplate for the formation of a variety of nanostructures. A phenomenological\nmodel based on electromigration of charged mobile atoms explains the observed\ncurrent-polarity dependent behavior."
    },
    {
        "anchor": "Effects of Strain and Buffer Layer on Interfacial Magnetization in\n  Sr$_2$CrReO$_6$ Films Determined by Polarized Neutron Reflectometry: We have determined the depth-resolved magnetization structures of a series of\nhighly ordered Sr$_{2}$CrReO$_{6}$ (SCRO) ferrimagnetic epitaxial films via\ncombined studies of x-ray reflectometry, polarized neutron reflectometry and\nSQUID magnetometry. The SCRO films deposited directly on\n(LaAlO$_3$)$_{0.3}$(Sr$_2$AlTaO$_6$)$_{0.7}$ or SrTiO$_{3}$ substrates show\nreduced magnetization of similar width near the interfaces with the substrates,\ndespite having different degrees of strain. When the SCRO film is deposited on\na Sr$_{2}$CrNbO$_{6}$ (SCNO) double perovskite buffer layer, the width the\ninterfacial region with reduced magnetization is reduced, agreeing with an\nimproved Cr/Re ordering. However, the relative reduction of the magnetization\naveraged over the interfacial regions are comparable among the three samples.\nInterestingly, we found that the magnetization suppression region is wider than\nthe Cr/Re antisite disorder region at the interface between SCRO and SCNO.",
        "positive": "Convert widespread paraelectric perovskite to ferroelectrics: While nature provides a plethora of perovskite materials, only a few exhibits\nlarge ferroelectricity and possibly multiferroicity. The majority of perovskite\nmaterials have the non-polar CaTiO$_3$(CTO)structure, limiting the scope of\ntheir applications. Based on effective Hamiltonian model as well as\nfirst-principles calculations, we propose a general thin-film design method to\nstabilize the functional BiFeO$_3$(BFO)-type structure, which is a common\nmetastable structure in widespread CaTiO$_3$-type perovskite oxides. It is\nfound that the improper antiferroelectricity in CTO-type perovskite and\nferroelectricity in BFO-type perovskite have distinct dependences on mechanical\nand electric boundary conditions, both of which involve oxygen octahedral\nrotation and tilt. The above difference can be used to stabilize the highly\npolar BFO-type structure in many CTO-type perovskite materials."
    },
    {
        "anchor": "Kinetics of transformation, border of metastable miscibility gap in\n  Fe-Cr alloy and limit of Cr solubility in iron at 858 K: The study was aimed at determination of the position of the Fe-rich border of\nthe metastable miscibility gap (MMG) and of the solubility limit of Cr in iron\nat 858 K. Towards this end a Fe73.7Cr26.3 alloy was isothermally annealed at\n858 K in vacuum up to 8144 hours and M\\\"ossbauer spectra were recorded at room\ntemperature after every step of the annealing. Three spectral parameters viz.\nthe average hyperfine field, <B>, the average isomer shift, <IS>, and the\nprobability of the atomic configuration with no Cr atoms in the two-shell\nvicinity of the probe Fe atoms, P(0,0), gave evidence that the transformation\nprocess takes place in two stages. All three parameters could have been well\ndescribed in terms of the Johnson-Mehl-Avrami-Kolmogorov equation, yielding\nkinetics parameters. The first stage, associated with the phase decomposition,\nproceeded much faster than the second stage, associated with the alpha-to-sigma\nphase transformation. The most reliable estimation of the position of the MMG\nand that of the value of the Cr solubility limit was obtained from the\nannealing time dependence of <B>, namely 24.5 at.% Cr for the former and 20.3\nat.% Cr for the latter. A comparison of these figures with the recent phase\ndiagrams pertinent to Fe-Cr system was done.",
        "positive": "A route to minimally dissipative switching in magnets via THz phonon\n  pumping: Advanced magnetic recording paradigms typically use large temperature changes\nto drive switching which is detrimental to device longevity, hence finding\nnon-thermal routes is crucial for future applications. By employing atomistic\nspin-lattice dynamics simulations, we show efficient coherent magnetisation\nswitching triggered by THz phonon excitation in insulating single species\nmaterials. The key ingredient is excitation near the $P$-point of the spectrum\nin conditions where spins typically cannot be excited and when manifold $k$\nphonon modes are accessible at the same frequency. Our model predicts the\nnecessary ingredients for low-dissipative switching and provides new insight\ninto THz-excited spin dynamics."
    },
    {
        "anchor": "Finite-Temperature Micromagnetics of Hysterisis for Misaligned Single\n  Iron Nanopillars: We present micromagnetic results for the hysterisis of a single magnetic\nnanopillar which is misaligned with respect to the applied magnetic field. We\nprovide results for both a one dimensional stack of magnetic rotors and of full\nmicromagnetic simulations. The results are compared to the Stoner-Wohlfarth\nmodel.",
        "positive": "Structure determination of the indium-induced Si(111)-(4x1)\n  reconstruction by surface x-ray diffraction: A detailed structural model for the indium-induced Si(111)-(4x1) surface\nreconstruction has been determined by analyzing an extensive set of\nx-ray-diffraction data recorded with monochromatic ($\\hbar\\omega$ = 9.1 keV)\nsynchrotron radiation. The reconstruction is quasi-one-dimensional. The main\nfeatures in the structure are chains of silicon atoms alternating with zigzag\nchains of indium atoms on top of an essentially unperturbed silicon lattice.\nThe indium coverage corresponds to one monolayer. The structural model\nconsistently explains all previously published experimental data."
    },
    {
        "anchor": "Effect of Metal Doping on the Visible Light Absorption, Electronic\n  Structure and Mechanical Properties of Toxic-Free CsGeCl3 Metal Halide: Toxic-free metal halide perovskites have become forefront for\ncommercialization of the perovskite solar cells and optoelectronic devices. In\nthe present study, for the first time we show that particular metal doping in\nCsGeCl3 halide can considerably enhance the absorbance both in the visible and\nultraviolet light energy range. By using DFT based first principles method Mn\nand Ni is doped at the Ge-site of CsGeCl3 halide. We investigate the detailed\nstructural, optical, electronic and mechanical properties of all the doped\ncompositions theoretically. The study of optical properties exhibits that the\nabsorption edge of both Ni and Mn-doped CsGeCl3 is shifted toward the low\nenergy region (red shift) relative to the pristine one. An additional peak is\nobserved for both doped profile in the visible light energy region. The study\nof mechanical properties ensures that both the doped samples are mechanically\nstable and ductile as the pristine CsGeCl3. The study of electronic properties\nshows that the excitation of photoelectrons is easier due to the formation of\nintermediate states in Mn-doped CsGeCl3. As a result Mn-doped CsGeCl3 exhibits\nhigher absorptivity in the visible region than the Ni-doped counterpart. A\ncombinational analysis suggests that CsGe1-xMnxCl3 is the best lead free\ncandidate among the inorganic prsovskite materials for solar cell and\noptoelectronic applications.",
        "positive": "Principles of crystal growth of intermetallic and oxide compounds from\n  molten solutions: We present a tutorial on the principles of crystal growth of intermetallic\nand oxide compounds from molten solutions, with an emphasis on the fundamental\nprinciples governing the underlying phase equilibria and phase diagrams of\nmulticomponent systems."
    },
    {
        "anchor": "Is more Phase Segregation better for mixed halide perovskite devices:\n  Spatial randomness, Ion migration, and Non-radiative recombination: Phase segregation is a critical phenomenon that influences the stability and\nperformance of mixed halide perovskite based opto-electronic devices. In\naddition to the underlying physical mechanisms, the spatial pattern and\nrandomness associated with the nanoscale morphology of phase segregation\nsignificantly influence performance degradation a topic which, along with the\nmultitude of parameter combinations, has remained too complex to address so\nfar. Given this, with MAPbI1.5Br1.5 as a model system, here we address the\ninfluence of critical factors like the spatial randomness of phase segregation,\ninfluence of ion migration, and the effect of increased non radiative\nrecombination at material interfaces. Interestingly, our analytical model and\ndetailed statistical simulations indicate a unique trend morphology evolution\nwith increased phase segregation results, surprisingly, in a recovery in\nefficiency while non-radiative recombination at grain/domain boundaries results\nin efficiency degradation. Further, our quantitative and predictive estimates\nidentify critical parameters for interface states beyond which device\nvariability could be an important system level bottleneck. Indeed, these\nestimates are broadly applicable to systems which undergo phase segregation and\nhave interesting implications to perovskite based optoelectronic devices from\nstability concerns to engineering approaches that attempt to arrest phase\nsegregation.",
        "positive": "Structure and dielectric properties of BFN-KN solid solutions\n  synthesized through solution combustion route: We demonstrate that the solution combustion reaction (SCR) route is suitable\nfor the synthesis of phase pure (x)BaFe0.5Nb0.5O3-(1-x)KNbO3 (x = 0, 0.2, 0.4,\n0.6, 0.8, 1) (BFN-KN) solid solutions due to atomic level of mixing of\nprecursors than that of the solid-state reaction (SSR) route. A variation in\ncomposition 'x' of our double perovskite samples leads to a gradual variation\nin the structural disorder associated with the disorder in the distribution in\nthe cationic positions, the lattice strain, and the defects at the grain\nboundaries. With the increase in the BFN content in the solid solutions, a\ndecrease in bandgap and a corresponding change in the color of the samples are\nobserved. Furthermore, three distinct characteristic features in the\nfrequency-dependent polarization behavior in our samples are observed at\ndifferent frequencies. These features observed to be sustaining up to gradually\nincreasing frequencies are assigned to (1) the interfacial polarization\noriginating due to the structural disorder present at the grain boundaries, (2)\nthe cationic positions leading to tilting/expansion of oxygen octahedra, and\n(3) the ionic size mismatch leading to strain distribution. The results are\nwell supported by the results obtained for the microstructural, structural, and\noptical properties of our samples. Hence, our work provides a better\nunderstanding of the dielectric polarization behavior of double perovskites."
    },
    {
        "anchor": "Deformation-induced homogenization of the multi-phase senary\n  high-entropy alloy MoNbTaTiVZr processed by high-pressure torsion: Dendritic microstructures are frequently observed in as-solidified refractory\nhigh-entropy alloys (RHEAs), and their homogenization typically requires a\nlong-term heat treatment at extremely high temperatures. High-pressure torsion\n(HPT) has been shown to be capable of mixing immiscible systems at room\ntemperature, and therefore represents a promising technique for homogenizing\ndendritic RHEAs. In this work, the as-solidified RHEA MoNbTaTiVZr was processed\nup to 40 revolutions by HPT. It was found that the dendritic microstructure was\neliminated, resulting in a chemical homogeneity at a von Mises equivalent shear\nstrain of about 400. The study of deformation mechanism showed an initial\nstrain localization, followed by a co-deformation of the dendritic and\ninterdendritic regions. In the co-deformation step, the Zr-rich interdendritic\nregion gradually disappeared. The deformation-induced mixing also led to the\nformation of an ultra-fine grained (UFG) microstructure, exhibiting a grain\nsize of approximately 50 nm. The microhardness increased from 500 HV in the\nas-solidified to 675 HV in the homogenized UFG state. The underlying mechanisms\nresponsible for the microhardness enhancement, such as grain refinement and\nsolid solution strengthening, were also discussed.",
        "positive": "Interaction between magnetic moments and itinerant carriers in d0\n  ferromagnetic SiC: Elucidating the interaction between magnetic moments and itinerant carriers\nis an important step to spintronic applications. Here, we investigate magnetic\nand transport properties in d0 ferromagnetic SiC single crystals prepared by\npostimplantation pulsed laser annealing. Magnetic moments are contributed by\nthe p states of carbon atoms, but their magnetic circular dichroism is\ndifferent from that in semi-insulating SiC samples. The anomalous Hall effect\nand negative magnetoresistance indicate the influence of d0 spin order on free\ncarriers. The ferromagnetism is relatively weak in N-implanted SiC compared\nwith that in Al-implanted SiC after annealing. The results suggest that d0\nmagnetic moments and itinerant carriers can interact with each other, which\nwill facilitate the development of SiC spintronic devices with d0\nferromagnetism."
    },
    {
        "anchor": "FMR-related phenomena in spintronic devices: Spintronic devices, such as non-volatile magnetic random access memories and\nlogic devices, have attracted considerable attention as potential candidates\nfor future high efficient data storage and computing technology. In a heavy\nmetal or other emerging material with strong spin-orbit coupling (SOC), the\ncharge currents induce spin currents or spin accumulations via SOC. The\ngenerated spin currents can exert spin-orbit torques (SOTs) on an adjacent\nferromagnet, which opens up a new way to realize magnetization dynamics and\nswitching of the ferromagnetic layer for spintronic devices. In the SOT scheme,\nthe charge-to-spin interconversion efficiency (SOT efficiency) is an important\nfigure of merit for applications. For the effective characterization of this\nefficiency, the ferromagnetic resonance (FMR) based methods, such as the spin\ntransfer torque ferromagnetic resonance (ST-FMR) and the spin pumping, are\ncommon utilized in addition to low frequency harmonic or dc measurements. In\nthis review, we focus on the ST-FMR measurements for the evaluation of the SOT\nefficiency. We provide a brief summary of the different ST-FMR setups and data\nanalysis methods. We then discuss ST-FMR and SOT studies in various materials,\nincluding heavy metals and alloys, topological insulators, two dimensional (2D)\nmaterials, interfaces with strong Rashba effect, antiferromagnetic materials,\ntwo dimensional electron gas (2DEG) in oxide materials and oxidized nonmagnetic\nmaterials.",
        "positive": "Possible routes for synthesis of new boron-rich Fe-B and Fe(1-x)Cr(x)B4\n  compounds: We use ab initio calculations to examine thermodynamic factors that could\npromote the formation of recently proposed unique oP10-FeB4 and oP12-FeB2\ncompounds. We demonstrate that these compact boron-rich phases are stabilized\nfurther under pressure. We also show that chromium tetraboride is more stable\nin the new oP10 rather than the reported oI10 structure which opens up the\npossibility of realizing an oP10-Fe(x)Cr(1-x)B4 pseudobinary material. In\naddition to exhibiting remarkable electronic features, oP10-FeB4 and oP12-FeB2\nare expected to be harder than the known Fe-B compounds commonly used for hard\ncoating applications."
    },
    {
        "anchor": "When are rough surfaces sticky?: At the molecular scale there are strong attractive interactions between\nsurfaces, yet few macroscopic surfaces are sticky. Extensive simulations of\ncontact by adhesive surfaces with roughness on nanometer to micrometer scales\nare used to determine how roughness reduces the area where atoms contact and\nthus weakens adhesion. The material properties, adhesive strength and roughness\nparameters are varied by orders of magnitude. In all cases the area of atomic\ncontact rises linearly with load, and the prefactor rises linearly with\nadhesive strength for weak interactions. Above a threshold adhesive strength,\nthe prefactor changes sign, the surfaces become sticky and a finite force is\nrequired to separate them. A parameter-free analytic theory is presented that\ndescribes changes in these numerical results over up to five orders of\nmagnitude in load. It relates the threshold strength to roughness and material\nproperties, explaining why most macroscopic surfaces do not stick. The\nnumerical results are qualitatively and quantitatively inconsistent with\nclassical theories based on the Greenwood-Williamson approach that neglect the\nrange of adhesion and do not include asperity interactions.",
        "positive": "Effect of divalent Ba cation substitution with Sr on coupled multiglass\n  state in the magnetoelectric multiferroic compound Ba3NbFe3Si2O14: (Ba/Sr)3NbFe3Si2O14 is a magnetoelectric multiferroic with an incommensurate\nantiferromagnetic spiral magnetic structure which induces electric polarization\nat 26 K. The structure, as revealed by x-rays and neutrons, as well as static\nand dynamic magnetic and dielectric properties of these compounds have been\nstudied down to 6 K under different conditions. Both the compounds have similar\ncrystal structure but with different lattice constants down to 6 K. The Ba-and\nSr-compounds exhibit a transition at 26 K and 25 K respectively, as indicated\nby the specific heat capacity and dc specific magnetization, into an\nantiferromagnetic state. Although Ba and Sr are isovalent, they exhibit very\ndifferent static and dynamic magnetic behavior. The Ba-compound exhibits both\nthermal and magnetic field hysteresis with the thermal hysteresis decreasing\nwith increasing magnetic field, a behavior typical of glasses. The glassy\nbehavior is also clearly seen in the ac susceptibility studies which show a\ndispersive peak in the range 40 K to 90 K in the frequency range 10^1 Hz to\n10^4 Hz. The dispersive behavior follows a cluster glass critical slowing\ndynamics with a freezing temperature of 35 K and a critical exponent of 3.9, a\nvalue close to the 3-D Ising model. The Sr-compound however does not exhibit\nany dispersive behavior except for the invariant transition at 25 K in ac\nsusceptibility with no magnetic field hysteresis at all temperatures. The\ndielectric constant studied in the frequency range 10^1 Hz to 10^6 Hz also\nreflects the magnetic behavior of the two compounds. The Ba-compound has two\ndistinct dispersive peaks near TN and in the range 40 K to 125 K while the\nSr-compound has a single dispersive peak in the range 40 K to 80 K. The\nactivation energy of the high temperature dispersive peak in both compounds\nhowever is found to be similar, 71 meV and 65 meV respectively for Ba- and\nSr-compounds."
    },
    {
        "anchor": "Polarization, piezoelectric constants and elastic constants of ZnO, MgO\n  and CdO: We report first principles density functional calculations of the spontaneous\npolarizations, piezoelectric constants and elastic constants for the II-VI\nwurtzite structure ZnO, MgO and CdO. Using our self interaction corrected\nimplementation of density functional theory we obtain polarization values of we\nobtain polarization values of -0.05, -0.17 and -0.10 C/m$^2$, and piezoelectric\nconstants, $e_{33}$ ($e_{31}$) of 1.34 (-0.57), 2.26 (-0.38) and 1.67 (-0.48)\nC/m$^2$ for structurally relaxed ZnO, MgO and CdO respectively. These\nproperties are consistently larger in magnitude than the corresponding GaN, AlN\nand InN analogues. Therefore we predict that larger internal fields will be\nattainable in ZnO-based polarization field effect transistors than in\nequivalent GaN-based devices.",
        "positive": "FeTaSb and FeMnTiSb as promising thermoelectric materials: An ab initio\n  approach: Thermoelectricity in principle provides a pathway to put waste heat to good\nuse. Motivated by this we investigate thermal and electrical transport\nproperties of two new Fe-based Heusler alloys, FeTaSb and FeMnTiSb, by a first\nprinciples approach and semiclassical Boltzmann transport theory within the\nconstant relaxation-time approximation. We find a high power factor of\n\\textit{p}-doped FeTaSb, competitive with best performing Heusler alloy FeNbSb\nat 1100 K. The obtained power factor of \\textit{n}-doped FeMnTiSb at room\ntemperature is higher than that of both FeNbSb and FeTaSb. Remarkably, FeMnTiSb\ncan be used for both \\textit{n}-type and \\textit{p}-type legs in a\nthermoelectric module. The Seebeck coefficients of the two proposed systems are\nin line with those of earlier reported Heusler alloys. We also provide\nconservative estimates of the figure of merit for the two systems. Overall, our\nfindings suggest a high temperature thermoelectric potential of FeTaSb while\nthe low cost FeMnTiSb is a viable room temperature thermoelectric candidate\nmaterial."
    },
    {
        "anchor": "The ab initio amorphous materials database: Empowering machine learning\n  to decode diffusivity: Amorphous materials exhibit unique properties that make them suitable for\nvarious applications in science and technology, ranging from optical and\nelectronic devices and solid-state batteries to protective coatings. However,\ndata-driven exploration and design of amorphous materials is hampered by the\nabsence of a comprehensive database covering a broad chemical space. In this\nwork, we present the largest computed amorphous materials database to date,\ngenerated from systematic and accurate \\textit{ab initio} molecular dynamics\n(AIMD) calculations. We also show how the database can be used in simple\nmachine-learning models to connect properties to composition and structure,\nhere specifically targeting ionic conductivity. These models predict the Li-ion\ndiffusivity with speed and accuracy, offering a cost-effective alternative to\nexpensive density functional theory (DFT) calculations. Furthermore, the\nprocess of computational quenching amorphous materials provides a unique\nsampling of out-of-equilibrium structures, energies, and force landscape, and\nwe anticipate that the corresponding trajectories will inform future work in\nuniversal machine learning potentials, impacting design beyond that of\nnon-crystalline materials.",
        "positive": "Quantitative analysis of the blue-green single-photon emission from a\n  quantum dot in a thick tapered nanowire: Quantum dots acting as single photon emitters in the blue-green range are\nfabricated and characterized at cryogenic temperature. They consist in CdSe\ndots inserted in (Zn,Mg)Se nanowires with a thick shell. Photoluminescence\nspectra, decay curves and autocorrelation functions were measured under\nnonresonant continuous-wave and pulsed excitation. An analytical approach is\napplied simultaneously to the decay curves and correlation functions. It allows\na quantitative description of how these two quantities are affected by the\nexciton rise due to biexciton feeding, the bright exciton decay, the effect of\nthe dark exciton, and the re-excitation between two laser pulses. Linewidths at\nour limit of resolution (200 $\\mu$eV) are recorded. The reported correlation\ncounts vary from a full control by re-excitation from traps, to a small\ncontribution of re-excitation by mobile carriers or other QDs, as low as 5%."
    },
    {
        "anchor": "In Situ X-Ray Radiography and Tomography Observations of the\n  Solidification of Alumina Particles Suspensions. Part II: Steady State: This paper investigates the behaviour of colloidal suspensions of alumina\nparticles during directional solidification, by in situ high-resolution\nobservations using X-ray radiography and tomography. This second part is\nfocussed on the evolution of ice crystals during steady state growth (in terms\nof interface velocity) and on the particles redistribution taking place in this\nregime. In particular, it is shown that diffusion cannot determine the\nconcentration profile and the particles redistribution in this regime of\ninterface velocities (20-40 microns/s); constitutional supercooling arguments\ncannot be invoked to interpret particles redistribution. Particles are\nredistributed by a direct interaction with the moving solidification interface.\nSeveral parameters controlling the particles redistribution were identified,\nnamely the interface velocity, the particle size, the shape of the ice crystals\nand the orientation relationships between the crystals and the temperature\ngradient.",
        "positive": "Epitaxial Thin Films of the Giant-Dielectric-Constant Material\n  CaCu_3Ti_4O_{12} Grown by Pulsed-laser Deposition: Pulsed-laser deposition has been used to grow epitaxial thin films of the\ngiant-dielectric-constant material CaCu_3Ti_4O_{12} on LaAlO_3 and SrTiO_3\nsubstrates with or without various conducting buffer layers. The latter include\nYBa_2Cu_3O_7, La_{1.85}Sr_{0.15}CuO_{4+\\delta} and LaNiO_3. Above 100K - 150K\nthe thin films have a temperature independent dielectric constant as do single\ncrystals. The value of the dielectric constant is of the order of 1500 over a\nwide temperature region, potentially making it a good candidate for many\napplications. The frequency dependence of its dielectric properties below 100K\n- 150K indicates an activated relaxation process."
    },
    {
        "anchor": "Quantifying Confidence in DFT Predicted Surface Pourbaix Diagrams of\n  Transition Metal Electrode-Electrolyte Interfaces: Density Functional Theory (DFT) calculations have been widely used to predict\nthe activity of catalysts based on the free energies of reaction intermediates.\nThe incorporation of the state of the catalyst surface under the\nelectrochemical operating conditions while constructing the free energy diagram\nis crucial, without which even trends in activity predictions could be\nimprecisely captured. Surface Pourbaix diagrams indicate the surface state as a\nfunction of the pH and the potential. In this work, we utilize error-estimation\ncapabilities within the BEEF-vdW exchange correlation functional as an ensemble\napproach to propagate the uncertainty associated with the adsorption energetics\nin the construction of Pourbaix diagrams. Within this approach,\nsurface-transition phase boundaries are no longer sharp and are therefore\nassociated with a finite width. We determine the surface phase diagram for\nseveral transition metals under reaction conditions and electrode potentials\nrelevant for the Oxygen Reduction Reaction (ORR). We observe that our surface\nphase predictions for most predominant species are in good agreement with\ncyclic voltammetry experiments and prior DFT studies. We use the OH$^*$\nintermediate for comparing adsorption characteristics on Pt(111), Pt(100),\nPd(111), Ir(111), Rh(111), and Ru(0001) since it has been shown to have a\nhigher prediction efficiency relative to O$^*$, and find the trend\nRu>Rh>Ir>Pt>Pd for (111) metal facets, where Ru binds OH$^*$ the strongest. We\nrobustly predict the likely surface phase as a function of reaction conditions\nby associating c-values to quantifying the confidence in predictions within the\nPourbaix diagram. We define a confidence quantifying metric using which certain\nexperimentally observed surface phases and peak assignments can be better\nrationalized.",
        "positive": "A multi-grid Cellular Automaton model for simulating dendrite growth and\n  its application in additive manufacturing: The dendrite growth in casting and additive manufacturing is rather important\nand related to the formation of some defects. However, quantitatively\nsimulating the growth of dendrites with arbitrary crystallographic orientations\nin 3-dimension(3D) is still very challenging. In the present work, we develop a\nmulti-grid Cellular Automaton (CA) model for the dendrite growth. In this\nmodel, the interfacial area is further discretized into a child grid, on which\nthe decentered octahedron growth algorithm is performed. The model is\ncomprehensively and quantitatively verified by comparing with the prediction of\nanalytical models and a published x-ray imaging observation result, proving\nthat the model is quantitatively and morphologically accurate. After that, with\nthe temperature gradient and cooling rate extracted from a\nfinite-volume-method(FVM)-based thermal-fluid model, the model was applied in\nreproducing the dendrite growth process of nickel-based superalloy during a\nsingle-track electron beam melting process. The simulation results agree fairly\nwell with the experimental observation, demonstrating the feasibility and\neffectiveness of using the model in additive manufacturing."
    },
    {
        "anchor": "Modeling of Polymer Clay Nanocomposite for a Multiscale Approach: The mechanical property enhancement of polymer reinforced with nano-thin clay\nplatelets (of high aspect ratio) is associated with a high polymer-filler\ninterfacial area per unit volume. The ideal case of fully separated\n(exfoliated) platelets is generally difficult to achieve in practice: a typical\nnanocomposite also contains multilayer stacks of intercalated platelets. Here\nwe use numerical modelling to investigate how the platelet properties affect\nthe overall mechanical properties. The configuration of platelets is modelled\nusing a statistical interpretation of the Representative Volume Element (RVE)\napproach, in which an ensemble of \"sample\" heterogeneous material is generated\n(with periodic boundary conditions). A simple Monte Carlo algorithm is used to\nplace non-intersecting platelets in the RVE according to a specified set of\nstatistical distributions. The effective stiffness of the platelet-matrix\nsystem is determined by measuring the stress (using standard Finite Element\nanalysis) produced as a result of applying a small deformation to the\nboundaries, and averaging over the entire statistical ensemble. In this work we\ndetermine the way in which the platelet properties (curvature, filling\nfraction, stiffness, aspect ratio) and the number of layers in the stack affect\nthe overall stiffness enhancement of the nanocomposite. Thus, we bridge the gap\nbetween behaviour on the macroscopic scale with that on the scale of the\nnano-reinforcement, forming part of a multi-scale modelling framework.",
        "positive": "Synthesis, crystal structure, and properties of novel perovskite\n  oxychalcogenides, Ca2CuFeO3Ch (Ch = S, Se): Two new perovskite oxychalcogenides, Ca2CuFeO3S and Ca2CuFeO3Se, have been\nsynthesized in evacuated quartz tubes. They crystallize in P4/nmm space group\nwith lattice parameters a = 3.8271(1), c = 14.9485(2) {\\AA} and a = 3.8605(1),\nc = 15.3030(2) {\\AA} for Ca2CuFeO3S and Ca2CuFeO3Se, respectively. They appear\nto be the first layered chalcogenide perovskites involving calcium and are\nstructural analogs of the corresponding Sr and Ba compounds. The new compounds\nexhibit semiconducting properties with energy gap decreasing from the\noxysulfide to the oxyselenide. Possibility of introducing Ca2+ into structures\nof known layered oxychalcogenides and oxypnictides is discussed."
    },
    {
        "anchor": "Thermomechanical conversion in metals: dislocation plasticity model\n  evaluation of the Taylor-Quinney coefficient: Using a partitioned-energy thermodynamic framework which assigns energy to\nthat of atomic configurational stored energy of cold work and\nkinetic-vibrational, we derive an important constraint on the Taylor-Quinney\ncoefficient, which quantifies the fraction of plastic work that is converted\ninto heat during plastic deformation. Associated with the two energy\ncontributions are two separate temperatures -- the ordinary temperature for the\nthermal energy and the effective temperature for the configurational energy. We\nshow that the Taylor-Quinney coefficient is a function of the thermodynamically\ndefined effective temperature that measures the atomic configurational disorder\nin the material. Finite-element analysis of recently published experiments on\nthe aluminum alloy 6016-T4 \\citep{neto_2020}, using the thermodynamic\ndislocation theory (TDT), shows good agreement between theory and experiment\nfor both stress-strain behavior and temporal evolution of the temperature. The\nsimulations include both conductive and convective thermal energy loss during\nthe experiments, and significant thermal gradients exist within the simulation\nresults. Computed values of the differential Taylor-Quinney coefficient are\nalso presented and suggest a value which differs between materials and\nincreases with increasing strain.",
        "positive": "Correlations Between Local Elastic Heterogeneities and Overall Elastic\n  Properties in Metallic Glasses: The common notion suggests that metallic glasses (MGs) are a homogeneous\nsolid at the macroscopic scale; however, recent experiments and simulations\nindicate that MGs contain nano-scale elastic heterogeneities. Despite the\nfundamental importance of these findings, a quantitative understanding is still\nlacking for the local elastic heterogeneities intrinsic to MGs. On the basis of\nEshelby's theory, here we develop a micromechanical model that correlates the\nproperties of the local elastic heterogeneities, being very difficult to\nmeasure experimentally, to the measurable overall elastic properties of MGs,\nsuch as shear/bulk modulus and Poisson's ratio. Our theoretical modeling is\nverified by the experimental data obtained from various MGs annealed to\ndifferent degrees. Particularly, we revealed that the decrease of Poisson's\nratio upon annealing of MGs is associated with a much large shear softening\nover hydrostatic-pressure softening, and $vice$ $versa$ in local elastic\ninhomogeneities. The relative extent of the bulk versus shear modulus softens\nis extracted for different MGs, and is found to closely depend on the specific\ncomposition and their ductility. The implication of our results on the\nPoisson's ratio criterion on the ductility as well as the aging dynamics in MGs\nis discussed."
    },
    {
        "anchor": "Charge multipoles correlations and order in Cs$_2$TaCl$_6$: We examine the role of charge, structural, and spin degrees of freedom in the\npreviously poorly understood phase transition in the 5$d^1$ transition-metal\ndouble perovskite Cs$_2$TaCl$_6$, using a combination of computational and\nexperimental techniques. Our heat capacity measurements of single-crystalline\nCs$_2$TaCl$_6$, reveal a clear anomaly at the transition temperature,\n$T_\\mathrm{Q}$, which was not previously observed in polycrystalline samples.\nDensity functional calculations indicate the emergence of local charge\nquadrupoles in the cubic phase, mediated by the paramagnetic spins or local\nstructural distortions which then develop into long-range ordered charge\nquadrupoles in the tetragonal phase. Our resonant elastic x-ray scattering on\nCs$_2$TaCl$_6$, single crystals lend support to our calculations. Our work\nprovides new insight into the phase transition in Cs$_2$TaCl$_6$, at\n$T_\\mathrm{Q}$, and demonstrates the utility of this combination of techniques\nin understanding the complex physics of hidden orders in paramagnetic\nspin-orbit-entangled compounds.",
        "positive": "4D-STEM elastic stress state characterisation of a TWIP steel nanotwin: We measure the stress state in and around a deformation nanotwin in a\ntwinning-induced plasticity (TWIP) steel. Using four-dimensional scanning\ntransmission electron microscopy (4D-STEM), we measure the elastic strain field\nin a 68.2-by-83.1 nm area of interest with a scan step of 0.36 nm and a\ndiffraction limit resolution of 0.73 nm. The stress field in and surrounding\nthe twin matches the form expected from analytical theory and is on the order\nof 15 GPa, close to the theoretical strength of the material. We infer that the\nmeasured back-stress limits twin thickening, providing a rationale for why TWIP\nsteel twins remain thin during deformation, continuously dividing grains to\ngive substantial work hardening. Our results support modern mechanistic\nunderstanding of the influence of twinning on crack propagation and\nembrittlement in TWIP steels."
    },
    {
        "anchor": "Can we predict interface dipoles based on molecular properties?: We apply high-throughput DFT calculations and symbolic regression to hybrid\ninorganic/organic interfaces with the intent to extract physically meaningful\ncorrelations between the adsorption-induced work function modifications and the\nproperties of the constituents. We separately investigate two cases:\nHypothetical, free standing self-assembled monolayers with a large intrinsic\ndipole moment, and metal-organic interfaces with a large charge-transfer\ninduced dipole. For the former we find - without notable prior assumptions -\nthe Topping model, as expected from literature. For the latter, highly accurate\ncorrelations are found, which are, however, clearly unphysical.",
        "positive": "Sub micron-precision sample holder for accurate re-positioning of\n  samples in Scanning Force Microscopy: Scanning Probe Microscopy allows for extreme resolution down to the atomic\nscale. Unfortunately, total scanning range is rather limited, therefore finding\na specific position on the sample is tedious. This is an important limitation\nof many Scanning Probe Microscopes, in particular when the sample has to be\nremoved for some kind of treatment and then re-allocated to characterize the\nsame position where the previous experiment had been performed. In the present\nwork we describe two simple and compact sub micron-precision sample holders\nthat can be easily integrated in to a commercial Scanning Force Microscopy\nsystem. The design is based either on a traditional kinematic mounting or on\nself-adjustment of the sample holder and the upper piece of the piezoelectric\nscanner as the glue used to assemble the final setup solidifies. With these\nsample holders a specific sample position is automatically recovered to within\nabout 100 nanometers, and thus well within the typical range of a piezoelectric\nscanner. Our experimental setup therefore allows ex-situ manipulation of the\nsample and SFM imaging of the same region without the aid of an optical\nmicroscope, positioning marks and tedious re-allocation."
    },
    {
        "anchor": "The relative contributions of TWIP and TRIP to strength in fine grained\n  medium-Mn steels: A medium Mn steel of composition Fe-4.8Mn-2.8Al-1.5Si-0.51C (wt.\\%) was\nprocessed to obtain two different microstructures representing two different\napproaches in the hot rolling mill, resulting in equiaxed vs. a mixed equiaxed\nand lamellar microstructures. Both were found to exhibit a simultaneous\nTWIP$+$TRIP plasticity enhancing mechanism where deformation twins and\n$\\alpha'$-martensite formed independently of twinning with strain. Interrupted\ntensile tests were conducted in order to investigate the differences in\ndeformation structures between the two microstructures. A constitutive model\nwas used to find that, surprisingly, twinning contributed relatively little to\nthe strength of the alloy, chiefly due to the fine initial slip lengths that\nthen gave rise to relatively little opportunity for work hardening by grain\nsubdivision. Nevertheless, with lower high-cost alloying additions than\nequivalent Dual Phase steels (2-3 wt\\% Mn) and greater ductility, medium-Mn\nTWIP$+$TRIP steels still represent an attractive area for future development.",
        "positive": "Nonlocal Modeling in High-Velocity Impact Failure of 6061-T6 Aluminum: In this paper, we present numerical simulations with local and nonlocal\nmodels under dynamic loading conditions. We show that for finite element (FE)\ncomputations of high-velocity, impact problems with softening material models\nwill result in spurious post-bifurcation mesh dependency solutions. To\nalleviate numerical instability associated within the post-bifurcation regime,\na characteristic length scale was added to the constitutive relations based on\ncalibration of the series of different notch specimen tests. This work aims to\nassess the practical relevance of the modified model to yield mesh independent\nresults in the numerical simulations of high-velocity impact problems. To this\nend, we consider the problem of a rigid projectile moving at a range of\nvelocities between 89-107 m/s, colliding against a 6061-T6 Aluminum disk. A\nmaterial model embedded with a characteristic length scale in the manner\nproposed by Pijaudier-Cabot and Bazant (1987), but in the context of concrete\ndamage, was utilized to describe the damage response of the disk. The numerical\nresult shows that the addition of a characteristic length scale to the\nconstitutive model does eliminate the pathological mesh dependency and shows\nexcellent agreements between numerical and experimental results. Furthermore,\nthe application of a nonlocal model for higher strain rate behavior shows the\nability of the model to address intense localized deformations, irreversible\nflow, softening, and final failure."
    },
    {
        "anchor": "Shock Response and Phase Transitions of MgO at Planetary Impact\n  Conditions: The moon-forming impact and the subsequent evolution of the proto-Earth is\nstrongly dependent on the properties of materials at the extreme conditions\ngenerated by this violent collision. We examine the high pressure behavior of\nMgO, one of the dominant constituents in the earth's mantle, using\nhigh-precision, plate impact shock compression experiments performed on Sandia\nNational Laboratories Z-Machine and extensive quantum simulations using Density\nFunctional Theory (DFT) and quantum Monte Carlo (QMC). The combined data span\nfrom ambient conditions to 1.2 TPa and 42,000 K, showing solid-solid and\nsolid-liquid phase boundaries. Furthermore our results indicate under impact\nthat the solid and liquid phases coexist for more than 100 GPa, pushing\ncomplete melting to pressures in excess of 600 GPa. The high pressure required\nfor complete shock melting places a lower bound on the relative velocities\nrequired for the moon forming impact.",
        "positive": "Impact of alloy disorder on the band structure of compressively strained\n  GaBiAs: The incorporation of bismuth (Bi) in GaAs results in a large reduction of the\nband gap energy (E$_g$) accompanied with a large increase in the spin-orbit\nsplitting energy ($\\bigtriangleup_{SO}$), leading to the condition that\n$\\bigtriangleup_{SO} > E_g$ which is anticipated to reduce so-called CHSH Auger\nrecombination losses whereby the energy and momentum of a recombining\nelectron-hole pair is given to a second hole which is excited into the\nspin-orbit band. We theoretically investigate the electronic structure of\nexperimentally grown GaBi$_x$As$_{1-x}$ samples on (100) GaAs substrates by\ndirectly comparing our data with room temperature photo-modulated reflectance\n(PR) measurements. Our atomistic theoretical calculations, in agreement with\nthe PR measurements, confirm that E$_g$ is equal to $\\bigtriangleup_{SO}$ for\n$\\textit{x} \\approx$ 9$%$. We then theoretically probe the inhomogeneous\nbroadening of the interband transition energies as a function of the alloy\ndisorder. The broadening associated with spin-split-off transitions arises from\nconventional alloy effects, while the behaviour of the heavy-hole transitions\ncan be well described using a valence band-anticrossing model. We show that for\nthe samples containing 8.5% and 10.4% Bi the difficulty in identifying a clear\nlight-hole-related transition energy from the measured PR data is due to the\nsignificant broadening of the host matrix light-hole states as a result of the\npresence of a large number of Bi resonant states in the same energy range and\ndisorder in the alloy. We further provide quantitative estimates of the impact\nof supercell size and the assumed random distribution of Bi atoms on the\ninterband transition energies in GaBi$_{x}$As$_{1-x}$. Our calculations support\na type-I band alignment at the GaBi$_x$As$_{1-x}$/GaAs interface, consistent\nwith recent experimental findings."
    },
    {
        "anchor": "Hydrogen-induced reversible spin-reorientation transition and magnetic\n  stripe domain phase in bilayer Co on Ru(0001): Imaging the change in the magnetization vector in real time by spin-polarized\nlow-energy electron microscopy, we observed a hydrogen-induced, reversible\nspin-reorientation transition in a cobalt bilayer on Ru(0001). Initially,\nhydrogen sorption reduces the size of out-of-plane magnetic domains and leads\nto the formation of a magnetic stripe domain pattern, which can be understood\nas a consequence of reducing the out-of-plane magnetic anisotropy. Further\nhydrogen sorption induces a transition to an in-plane easy-axis. Desorbing the\nhydrogen by heating the film to 400 K recovers the original out-of-plane\nmagnetization. By means of ab-initio calculations we determine that the origin\nof the transition is the local effect of the hybridization of the hydrogen\norbital and the orbitals of the Co atoms bonded to the absorbed hydrogen.",
        "positive": "Controlling magnetism in 2D CrI3 by electrostatic doping: The atomic thickness of two-dimensional (2D) materials provides a unique\nopportunity to control material properties and engineer new functionalities by\nelectrostatic doping. Electrostatic doping has been demonstrated to tune the\nelectrical and optical properties of 2D materials in a wide range, as well as\nto drive the electronic phase transitions. The recent discovery of atomically\nthin magnetic insulators has opened up the prospect of electrical control of\nmagnetism and new devices with unprecedented performance. Here we demonstrate\ncontrol of the magnetic properties of monolayer and bilayer CrI3 by\nelectrostatic doping using a dual-gate field-effect device structure. In\nmonolayer CrI3, doping significantly modifies the saturation magnetization,\ncoercive force and Curie temperature, showing strengthened (weakened) magnetic\norder with hole (electron) doping. Remarkably, in bilayer CrI3 doping\ndrastically changes the interlayer magnetic order, causing a transition from an\nantiferromagnetic ground state in the pristine form to a ferromagnetic ground\nstate above a critical electron density. The result reveals a strongly\ndoping-dependent interlayer exchange coupling, which enables robust switching\nof magnetization in bilayer CrI3 by small gate voltages."
    },
    {
        "anchor": "High carrier mobility in single-crystal PtSe2 grown by molecular beam\n  epitaxy on ZnO(0001): PtSe2 is attracting considerable attention as a high mobility two-dimensional\nmaterial with envisionned applications in microelectronics, photodetection and\nspintronics. The growth of high quality PtSe2 on insulating substrates with\nwafer-scale uniformity is a prerequisite for electronic transport\ninvestigations and practical use in devices. Here, we report the growth of\nhighly oriented few-layers PtSe2 on ZnO(0001) by molecular beam epitaxy. The\ncrystalline structure of the films is characterized with electron and X-ray\ndiffraction, atomic force microscopy and transmission electron microscopy. The\ncomparison with PtSe2 layers grown on graphene, sapphire, mica, SiO2 and\nPt(111) shows that among insulating substrates, ZnO(0001) yields films of\nsuperior structural quality. Hall measurements performed on epitaxial ZnO/PtSe2\nwith 5 monolayers of PtSe2 show a clear semiconducting behaviour and a high\nmobility in excess of 200 cm2V 1s-1 at room temperature and up to 447 cm2V-1s-1\nat low temperature.",
        "positive": "The nickel vacancy acceptor in NiO: doping beyond thermodynamic\n  equilibrium: This work reports on temperature-induced out-diffusion and concentration\ndecay of the prominent intrinsic point defect VNi (nickel vacancy) in the\nwide-gap p-type semiconductor nickel oxide (NiO). VNi can easily be introduced\ninto NiO thin films by offering high oxygen partial pressures during film\ngrowth, rendering nonstoichiometric semiconducting structures. However,\nexposure to lower oxygen supply after growth, e.g. in a standard atmosphere,\nusually leads to a gradual decrease of film conductivity, because the vacancy\nconcentration equilibrates. In this study, we observe this process in situ by\nperforming temperature-dependent measurements of the electrical conductivity on\na room temperature-grown NiO film. At a temperature of 420K under exclusion of\noxygen, the doping level decreases by a factor of 8 while the associated room\ntemperature dc conductivity drops by six orders of magnitude. At the same time,\nout-diffusion of the mobile VNi species can be indirectly observed through the\noccurrence of electrode polarization characteristics."
    },
    {
        "anchor": "Exchange interactions and magnetic force theorem: We critically reexamine the problem of interatomic exchange interactions,\nwhich describe the total energy change caused by infinitesimal rotations of\nspins near some equilibrium state. For the small variations, such interactions\ncan be always related to the response function. However, the form of this\nrelation can depend on additional approximations. Particularly, the commonly\nused magnetic force theorem (MFT) prescribes the linear relation between the\nexchange interactions and the response function, while the exact theory\nrequires this dependence to be inverse. We explore the origin and consequences\nof these differences in the definition for the wide class of materials:\nferromagnetic Ni, antiferromagnetic NiO, half-metallic CrO2, multiferroic\nHoMnO3, and layered magnets CrCl3 and CrI3. While in most of these cases, MFT\nproduces quite reasonable results and can be rigorously justifies in the long\nwavelength and strong-coupling limits, the exact formulation appears to be more\nconsistent, especially in dealing with two important issues, which typically\narise in the theory of exchange interactions: (i) the treatment of the ligand\nstates, and (ii) the choice of the suitable variable for the description of\ninfinitesimal rotations of spins. Both issues can be efficiently resolved by\nemploying the ideas of adiabatic spin dynamics supplemented with the exact\nexpression for the exchange interactions. Particularly, we propose a simple\n\"downfolding\" procedure for the elimination of the ligand spins by transferring\ntheir effect to the interaction parameters between the localized spins.\nFurthermore, we argue that the rotations of spin moments are more suitable for\nthe description of low-energy excitations, while the rotations of the whole\nmagnetization matrix cause much stronger perturbation in the system of spins.",
        "positive": "Favorable band alignment for photocatalysis at the strontium germanate\n  interface with silicon: Photocatalytic water splitting is a promising strategy for large-scale clean\nenergy production. However, efficient and low-cost solid-state photocatalysts\nare still lacking. We present here first-principles calculations to investigate\nthe suitability as photocathode of an epitaxial layer of strontium germanate on\na Si(100) single crystal. Conduction and valence bands offsets at the interface\nbetween these two semiconductors were determined using state-of-the-art\napproximations of density functional theory for the accurate prediction of band\nalignments. The resulting type-III band line-up is also confirmed by inspection\nof the spatially resolved density of states. It is concluded that the\nelectronic structure of the investigated heterostructure is favorable for\nphotocathodic functionality."
    },
    {
        "anchor": "Nonvolatile memory effects in hybrid devices of few-layer graphene and\n  ferroelectric polymer films: We report on the fabrication and electrical characterization of few-layer\ngraphene (FLG) devices coated with a ferroelectric polymer layer of\npoly(vinylidene fluoride/trifluoroethylene) [P(VDF/TrFE)]. Highly stable and\nreliable resistance changes were observed under floating conditions, which were\ndependent on the back gate voltage applied beforehand. Nonvolatile memory\nfunctionality in the hybrid FLG-P(VDF/TrFE) devices is attributed to a remanent\nelectric field induced by the ferroelectric polarization of the P(VDF/TrFE)\nlayer.",
        "positive": "Path Integral Methods in the Su-Schrieffer-Heeger Polaron Problem: I propose a path integral description of the Su-Schrieffer-Heeger\nHamiltonian, both in one and two dimensions, after mapping the real space model\nonto the time scale. While the lattice degrees of freedom are classical\nfunctions of time and are integrated out exactly, the electron particle paths\nare treated quantum mechanically. The method accounts for the variable range of\nthe electronic hopping processes. The free energy of the system and its\ntemperature derivatives are computed by summing at any $T$ over the ensemble of\nrelevant particle paths which mainly contribute to the total partition\nfunction. In the low $T$ regime, the {\\it heat capacity over T} ratio shows un\nupturn peculiar to a glass-like behavior. This feature is more sizeable in the\nsquare lattice than in the linear chain as the overall hopping potential\ncontribution to the total action is larger in higher dimensionality. The\neffects of the electron-phonon anharmonic interactions on the phonon subsystem\nare studied by the path integral cumulant expansion method."
    },
    {
        "anchor": "Singlet Oxygen Generation as a Major Cause for Parasitic Reactions\n  during Cycling of Aprotic Lithium-Oxygen Batteries: Non-aqueous metal-oxygen batteries depend critically on the reversible\nformation/decomposition of metal oxides on cycling. Irreversible parasitic\nreactions cause poor rechargeability, efficiency, and cycle life and have\npredominantly been ascribed to the reactivity of reduced oxygen species with\ncell components. These species, however, cannot fully explain the side\nreactions. Here we show that singlet oxygen forms at the cathode of a\nlithium-oxygen cell during discharge and from the onset of charge, and accounts\nfor the majority of parasitic reaction products. The amount increases during\ndischarge, early stages of charge, and charging at higher voltages, and is\nenhanced by the presence of trace water. Superoxide and peroxide appear to be\ninvolved in singlet oxygen generation. Singlet oxygen traps and quenchers can\nreduce parasitic reactions effectively. Awareness of the highly reactive\nsinglet oxygen in non-aqueous metal-oxygen batteries gives a rationale for\nfuture research towards achieving highly reversible cell operation.",
        "positive": "Dislocation assisted phase separation: a phase field study: Defects play a key role in deciding the mechanisms and kinetics of phase\ntransformations. In this paper, we show how dislocations influence phase\nseparation in alloys with miscibility gap. Specifically, depending on the ratio\nof pipe mobility to bulk mobility, it is seen that even in a system with\nnominal compositions outside the spinodal limit, spinodal phase separation is\npossible. Surprisingly, phase separation through both nucleation and growth,\nand spinodal decomposition, is seen concurrently (for the case of intersecting\ndislocations). Finally, the prominent role played by dislocations in\ninfluencing the morphology of precipitates is explored. We show that these\nresults agree qualitatively with recent experimental results in iron based\nsystems obtained using Atom Probe Tomography (APT)."
    },
    {
        "anchor": "Gate Voltage Control of Transition Metal Dichalcogenide Monolayers\n  Quantum Yield: Two-dimensional transition metal dichalcogenide (2D-TMD) monolayers, which\nreveal remarkable semiconductor properties, are the subject of active\nexperimental research.Recently it has been shown experimentally that quantum\nyield in MoS2 and WSe2 monoatomic layers can reach values close to unity when\nelectrostatic doping makes them intrinsic semiconductors. However, the\navailable theoretical description does not give an understanding of the\nphysical mechanisms underlying in the gate voltage control of quantum\nyield.This work is an attempt to propose a consistent semi-phenomenological\ntheory of photo-induced charge carriers relaxation in 2D-TMDs, which allows\nobtaining an analytical dependence of the quantum yield on the voltage applied\nto the FET gate. We consider a standard experimental situation, when the 2D-TMD\nmonolayer and the metal gate are plates of a flat capacitor, and the capacitor\ncharge is proportional to the gate voltage. The dependences of the TMD\nmonolayers quantum yield on the gate voltage and the carrier generation rate\nhave been calculated for the cases of the prevailing recombination of free\nelectrons and holes (radiative and non-radiative Auger recombination) and\nrecombination of excitons (radiative and Auger recombination). In both cases\nanalytical expressions were derived for the dependence of quantum yield on the\ngate voltage and photo-induced carriers generation rate at a fixed gate\nvoltage. Quantitative agreement with experiment allows concluding about the\nrelevance of the proposed theoretical model for the description of carriers\nphoto-generation and recombination in 2D-TMD monolayers. Obtained results\ndemonstrate the possibilities of 2D-TMD quantum yield control by the gate\nvoltage and indicate that 2D-TMDs are promising candidates for modern\noptoelectronics devices.",
        "positive": "A Density Functional Theory Investigation of Carboranethiol\n  Self-Assembled Monolayer on Au(111): Isolated and full monolayer adsorption of various carboranethiol\n(C$_2$B$_{10}$H$_{12}$S) isomers on gold (111) surface have been investigated\nusing both the standard and van der Waals density functional theoretical\ncalculations. The effect of differing molecular dipole moment orientations on\nthe low energy adlayer geometries, the binding characteristics and the\nelectronic properties of the self-assembled monolayers of these isomers have\nbeen studied. Specifically, the binding energy and work function changes\nassociated with different molecules show a correlation with their dipole\nmoments. The adsorption is favored for the isomers with dipole moments parallel\nto the surface. Of the two possible unit cell structures, the (5$\\times$5) was\nfound to be more stable than the ($\\sqrt{19}\\times\\sqrt{19}$)R23.4$^o$ one."
    },
    {
        "anchor": "Strain evolution in GaN Nanowires: from free-surface objects to\n  coalesced templates: Top-down fabricated GaN nanowires, 250 nm in diameter and with various\nheights, have been used to experimentally determine the evolution of strain\nalong the vertical direction of 1-dimensional objects. X-ray diffraction and\nphotoluminescence techniques have been used to obtain the strain profile inside\nthe nanowires from their base to their top facet for both initial compressive\nand tensile strains. The relaxation behaviors derived from optical and\nstructural characterizations perfectly match the numerical results of\ncalculations based on a continuous media approach. By monitoring the elastic\nrelaxation enabled by the lateral free-surfaces, the height from which the\nnanowires can be considered strain-free has been estimated. Based on this\nresult, NWs sufficiently high to be strain-free have been coalesced to form a\ncontinuous GaN layer. X-ray diffraction, photoluminescence and\ncathodoluminescence clearly show that despite the initial strain-free nanowires\ntemplate, the final GaN layer is strained.",
        "positive": "Unoccupied surface and interface states in Pd thin films deposited on\n  Fe/Ir(111) surface: We present a systematic first-principles study of the electronic surface\nstates and resonances occuring in thin films of Pd of various thicknesses\ndeposited on a single ferromagnetic monolayer of Fe on top of Ir(111)\nsubstrate. This system is of interest since one Pd layer deposited on\nFe/Ir(111) hosts small magnetic skyrmions. The latter are topological magnetic\nobjects with swirling spin-textures with possible implications in the context\nof spintronic devices since they have the potential to be used as magnetic bits\nfor information technology. The stabilization, detection and manipulation of\nsuch non-collinear magnetic entities require a quantitative investigation and a\nfundamental understanding of their electronic structure. Here we investigate\nthe nature of the unoccupied electronic states in Pd/Fe/Ir(111), which are\nessential in the large spin-mixing magnetoresistance (XMR) signature captured\nusing non spin-polarized scanning tunnelling microscopy [Crum et al., Nat.\nCommun. {\\bf 6} 8541 (2015); Hanneken et al., Nat. Nanotech. {\\bf 10}, 1039\n(2015)]. To provide a complete analysis, we investigate bare Fe/Ir(111) and\nPd$_{n=2,7}$/Fe/Ir(111) surfaces. Our results demonstrate the emergence of\nsurface and interface states after deposition of Pd monolayers, which are\nstrongly impacted by the large spin-orbit coupling of Ir surface."
    },
    {
        "anchor": "Dislocation Pinning in Helium-Implanted Tungsten: A Molecular Dynamics\n  Study: The interaction of edge dislocation with helium-implantation-induced defects\nin tungsten is investigated using molecular dynamics. Following prior\ninvestigations, we consider defects with two helium ions in a vacancy with a\nself-interstitial bound to it (He2V-SIA). Our observations suggest 3-10\nHe2V-SIA cluster together, with their pinning strength on glide dislocations\nincreasing with size. For all cluster sizes, the dislocation bows around the\ncluster, until it gets unpinned, carrying the SIAs with it and leaving behind a\nhelium-vacancy complex and newly created vacancies in its wake. The remnant\nhelium-vacancy complex has little pinning effect, highlighting the\ndefect-clearing process. A total solute hardening force for a distribution of\nclusters of different sizes, induced by 3000 appm of helium, is found to be\napproximately 700 MPa. This is in good agreement with the corresponding value\nof 750 MPa estimated in a previously developed crystal plasticity model\nsimulating the deformation behaviour of the helium-implanted tungsten.",
        "positive": "Electronic and magnetic structures and bonding properties of Ce2CrN3 and\n  U2CrN3 from first principles: The electronic and magnetic structures of A2CrN3 (A = Ce, U) ternary\ncompounds calculated based on band magnetism within DFT exhibit different\nbehaviors of the nf elements (n = 4, 5 resp.). Charge analysis allows to\nformally express the two compounds as A2Cr 5+ N3 5- thus classifying them as\ncovalent nitrides, i.e. far from formal exchange of +- 9 electrons. From\nestablishing the energy-volume equations of state, the two compounds are found\nwith hardness magnitudes: B0(A=Ce) =192 GPa and B0(A=U) = 243 GPa, within range\nof oxides due to covalent metal-nitrogen bonding shown as based on overlap\nmatrix analysis. The uranium compound is harder due to a smaller volume and\nless compressible U versus Ce metals. Ce2CrN3 exhibits large magnetization on\nCr (1.94BM) and a very small moment develops on cerium (0.14 BM) pointing out\nto an intermediate valence state while in U2CrN3, M(Cr) = 0.49 BM and M(U) =\n0.97BM. These results are stressed by broad band-like density of states (DOS)\nbehavior for A=U and localized DOS for A=Ce. Both compounds are found\nferromagnetic in the ground state"
    },
    {
        "anchor": "One MAX phase, different MXenes: a guideline to understand the crucial\n  role of etching conditions on Ti$_3$C$_2$T$_x$ surface chemistry: MXenes are a new, and growing, family of 2D materials with very promising\nproperties for a wide variety of applications. Obtained from the etching of MAX\nphases, numerous properties can be targeted thanks to the chemical richness of\nthe precursors. Herein, we highlight how etching agents govern surface\nchemistries of Ti$_3$C$_2$T$_x$, the most widely studied MXene to date. By\ncombining characterization tools such as X-ray diffraction, X-ray\nphotoelectron, Raman and electron energy loss spectroscopies, scanning and\ntransmission electron microscopies and a surface sensitive electrochemical\nreaction-the hydrogen evolution reaction, HER-we clearly demonstrate that the\netching agent (HF, LiF/HCl or FeF$_3$/HCl) strongly modifies the nature of\nsurface terminal groups (F, OH and/or O), oxidation sensitivity, delamination\nability, nature of the inserted species, interstratification, concentration of\ndefects and size of flakes. Beyond showing how using these different\ncharacterization tools to analyze MXenes, this work highlights that the MXene\nsynthesis routes can influence targeted applications.",
        "positive": "Longitudinal Spin Seebeck Effect Free from the Proximity Nernst Effect: This letter provides evidence for intrinsic longitudinal spin Seebeck effects\n(LSSEs) that are free from the anomalous Nernst effect (ANE) caused by an\nextrinsic proximity effect. We report the observation of LSSEs in Au/Y3Fe5O12\n(YIG) and Pt/Cu/YIG systems, showing that LSSE appears even when the mechanism\nof the proximity ANE is clearly removed. In the conventional Pt/YIG structure,\nfurthermore, we separate the LSSE from the ANE by comparing the voltages in\ndifferent magnetization and temperature-gradient configurations; the ANE\ncontamination was found to be negligibly small even in the Pt/YIG structure."
    },
    {
        "anchor": "Electrocatalytic Hydrogen Evolution Reaction on Edges of a Few Layer\n  Molybdenum Disulfide Nanodots: The design and development of inexpensive highly efficient electrocatalysts\nfor hydrogen production, underpins several emerging clean-energy technologies.\nIn this work, for the first time, molybdenum disulfide (MoS2) nanodots have\nbeen synthesized by ionic liquid assisted grinding exfoliation of bulk\nplatelets and isolated by sequential centrifugation. The nanodots have a\nthickness of up to 7 layers (4 nm) and an average lateral size smaller than 20\nnm. Detailed structural characterization established that the nanodots retained\nthe crystalline quality and low oxidation states of the bulk material. The\nsmall lateral size and reduced number of layers provided these nanodots with an\neasier path for the electron transport and plentiful active sites for the\ncatalysis of hydrogen evolution reaction (HER) in acidic electrolyte. The MoS2\nnanodots exhibited good durability and a Tafel slope of 61 mVdec-1 with an\nestimated onset potential of -0.09 V vs RHE, which are considered among the\nbest values achieved for 2H phase. It is envisaged that this work may provide a\nsimplistic route to synthesize a wide range of 2D layered nanodots that have\napplications in water splitting and other energy related technologies.\nKEYWORDS: MoS2 nanosheets, hydrogen evolution reaction, electrocatalysis,\nedges, nanodots, ionic liquid exfoliation, water splitting",
        "positive": "Core-structure and lattice resistance of twinning dislocations in fcc\n  metals: Metals with fcc structure may exhibit deformation twinning under specific\nconditions, which is an interesting but somewhat elusive aspect of their\ndeformation behavior. It is well acknowledged that the phenomenon occurs\nthrough the activities of twinning partial dislocations. However, the lack of a\ncomprehensive understanding of their fundamental properties obstructs the\ndevelopment of detailed multiscale models of crystal plasticity in the fcc\nmetals. Here we explore the core-structures and lattice friction of twinning\npartials through atomistically informed numerical modeling. To this end, we\nchoose four fcc crystals with widely differing stacking fault energies. Using\nthe semi-discrete variational Peierls Nabarro model, we compute the core-widths\nand Peierls stresses of edge and screw twinning dislocations. Apart from the\nconventional layer-by-layer model of twin nucleation, the recently proposed\nalternate-shear model has also been examined. In the latter case, a negative\nstable fault energy has been observed, which is large enough to overcome the\nPeierls barrier. This study also highlights the significance of incorporating\nthe surface correction, the absence of which leads to an overestimation of the\nintrinsic lattice resistance of the twinning dislocations."
    },
    {
        "anchor": "Mechanical properties of AlMgB14-related boron carbide structures. A\n  first principle study: We examine the effects produced by replacing B-B interlayer bonds by C-C\nbonds in AlMgB14-related boron network on its mechanical properties. The\nelastic constants, Vickers hardness and shear strength are evaluated by means\nof first principle computer simulations on the basis of density functional\ntheory. The results of simulations suggest a possibility of existence of\nseveral orthorhombic boron carbide phases with strongly enhanced mechanical\nproperties with the Young modulus and Vickers hardness being within the range\nof 550-600 GPa and 43-50 GPa, respectively",
        "positive": "Scattering from dilute ferrofluid suspensions in soft polymer gels: Small angle neutron and x-ray scattering methods are used to investigate the\nstructure of dilute suspensions of two different ferrofluid systems dispersed\nin soft polyacrylamide hydrogels. It is found that the particles in the fluid\nare fractal aggregates composed of smaller particles of radius ca. 5 nm. The\nfractal dimension is strongly dependent on sample, taking the value 1.7 in the\nfirst sample and 2.9 in the second sample. In the presence of a magnetic field\nthe aggregates orient, but are restricted in both their translational and\nrotational freedom. The effect of the gel elasticity is treated as a hindrance\nto the orientation process."
    },
    {
        "anchor": "Current-induced asymmetric magnetoresistance due to energy transfer via\n  quantum spin-flip process: Current-induced magnetization excitation is a core phenomenon for\nnext-generation magnetic nanodevices, and has been attributed to the\nspin-transfer torque (STT) that originates from the transfer of the spin\nangular momentum between a conduction electron and a local magnetic moment\nthrough the exchange coupling. However, the same coupling can transfer not only\nspin but also energy, though the latter transfer mechanism has been largely\nignored. Here we report on experimental evidence concerning the energy transfer\nin ferromagnet/heavy metal bilayers. The magnetoresistance (MR) is found to\ndepend significantly on the current direction down to low in-plane currents,\nfor which STT cannot play any significant role. Instead we find that the\nobserved MR is consistent with the energy transfer mechanism through the\nquantum spin-flip process, which predicts short wavelength,\ncurrent-direction-dependent magnon excitations in the THz frequency range. Our\nresults unveil another aspect of current-induced magnetic excitation, and open\na channel for the dc-current-induced generation of THz magnons.",
        "positive": "NMR and Mossbauer study of spin dynamics and electronic structure of\n  Fe{2+x}V{1-x}Al and Fe2VGa: In order to assess the magnetic ordering process in Fe2VAl and the related\nmaterial Fe2VGa, we have carried out nuclear magnetic resonance (NMR) and\nMossbauer studies. 27Al NMR relaxation measurements covered the temperature\nrange 4 -- 500 K in Fe(2+x)V(1-x)Al samples. We found a peak in the NMR\nspin-lattice relaxation rate, 27T1^-1, corresponding to the magnetic\ntransitions in each of these samples. These peaks appear at 125 K, 17 K, and\n165 K for x = 0.10, 0, and - 0.05 respectively, and we connect these features\nwith critical slowing down of the localized antisite defects. Mossbauer\nmeasurements for Fe2VAl and Fe2VGa showed lines with no hyperfine splitting,\nand isomer shifts nearly identical to those of the corresponding sites in Fe3Al\nand Fe3Ga, respectively. We show that a model in which local band filling leads\nto magnetic regions in the samples, in addition to the localized antisite\ndefects, can account for the observed magnetic ordering behavior."
    },
    {
        "anchor": "ElecTra Code: Full-Band Electronic Transport Properties of Materials: This paper introduces ElecTra, an open-source code which solves the\nlinearized Boltzmann transport equation in the relaxation time approximation\nfor charge carriers in a full-band electronic structure of arbitrary\ncomplexity, including their energy, momentum, and band-index dependence.\nElecTra stands for 'ELECtronic TRAnsport' and computes the electronic and\nthermoelectric transport coefficients electrical conductivity, Seebeck\ncoefficient, electronic thermal conductivity, and mobility, for semiconductor\nmaterials, for both unipolar and bipolar (small bandgap) materials. The code\nuses computed full-bands and relevant scattering parameters as inputs and\nconsiders single crystal materials in 3D and 2D. The present version of the\ncode (v1) considers: i) elastic scattering with acoustic phonons and inelastic\nscattering with non-polar optical phonons in the deformation potential\napproximation, ii) inelastic scattering with polar phonons, iii) scattering\nwith ionized dopants, and iv) alloy scattering. The user is given the option of\nintra- and inter-valley scattering considerations. The simulation output also\nincludes relevant relaxation times and mean-free-paths. The transport\nquantities are computed as a function of Fermi level position, doping density,\nand temperature. ElecTra can interface with any DFT code which saves the\nelectronic structure in the '.bxsf' format. In this paper ElecTra is validated\nagainst ideal electronic transport situations of known analytical solutions,\nexisting codes employing the constant relaxation time approximation, as well as\nexperimentally well-assessed materials such as Si, Ge, SiGe, and GaAs.",
        "positive": "Rare earth permanent magnets prepared by hot deformation process: Hot deformation process is one of the primary methods to produce anisotropic\nrare earth permanent magnets. Firstly, rapidly quenched powder flakes with\nnanocrystal structure are condensed into the full dense isotropic precursors by\nhot pressing process. And then, the prepared isotropic precursors are hot\ndeformed to produce high-anisotropy uniaxial bulk rare earth permanent magnets,\nin which the highly textured structure is obtained in the hot plastic\ndeformation process. The obtained hot-deformed magnets possess many advantages,\nsuch as near net-shape, outstanding corrosion resistance and ultrafine-grain\nstructure. The noteworthy effects of preparation parameters employed in\nhot-pressing and deformation processes on the magnetic properties and\nmicrostructures characterizations are systemically summarized in this academic\nmonograph. As a near net-shape technique, hot deformation process has\nnoteworthy advantages in producing irregular shape magnets, especially for\nradially oriented ring-shape magnets with high length-diameter ratio or thin\nwall. The difficulties in producing crack-free, homogeneous and non-decentered\nring-shaped magnets are basically resolved through mold design, adjustment of\ndeformation parameters and application of theoretical simulation. Considering\nthe characteristics of hot-deformed magnets, such as the grain shapes and\nsizes, anisotropic distribution of intergranular phases, etc., there is\npractical significance to study and improve the mechanical, electric properties\nand thermal stability to enlarge the applicable area of hot-deformed magnets or\nring-shaped magnets."
    },
    {
        "anchor": "Thermal rippling behavior of graphane: Thermal fluctuations of single layer hydrogenated graphene (graphane) are\ninvestigated using large scale atomistic simulations. By analyzing the mean\nsquare value of the height fluctuations $<h^2>$ and the height-height\ncorrelation function $H(q)$ for different system sizes and temperatures we show\nthat hydrogenated graphene is an un-rippled system in contrast to graphene. The\nheight fluctuations are bounded, which is confirmed by a $ H(q) $ tending to a\nconstant in the long wavelength limit instead of showing the characteristic\nscaling law $ q^{4-\\eta} (\\eta \\simeq 0.85)$ predicted by membrane theory. This\nunexpected behaviour persists up to temperatures of at least 900 K and is a\nconsequence of the fact that in graphane the thermal energy can be accommodated\nby in-plane bending modes, i.e. modes involving C-C-C bond angles in the\nbuckled carbon layer, instead of leading to significant out-of-plane\nfluctuations that occur in graphene.",
        "positive": "Bond disproportionation, charge self-regulation and ligand holes in s-p\n  and in d electron ABX3 perovskites by density functional theory: Some ABX3 perovskites exhibit different local environments (DLE) for the same\nB atoms in the lattice, an effect referred to as disproportionation,\ndistinguishing such compounds from perovskites that have single local\nenvironments (SLE). The basic phenomenology of disproportionation involves the\nabsence of B-atom charge ordering, the creation of different B-X bond length\nfor different local environments, the appearance of metal (in SLE) to insulator\n(in DLE) transition, and the formation of ligand holes. We point out that this\nphenomenology is common to a broad range of chemical bonding patterns in ABX3\ncompounds, either with s-p electron B-metal cations (BaBiO3, CsTlF3), or noble\nmetal cation (CsAuCl3), as well as d-electron cations (SmNiO3, CaFeO3). We show\nthat underlying much of this phenomenology is the self-regulating response,\nwhereby in strongly bonded metal-ligand systems with high lying ligand\norbitals, the system protects itself from creating highly charged cations by\ntransferring ligand electrons to the metal, thus preserving a nearly constant\nmetal charge in DLE, while creating B-ligand bond alternation and ligand-like\nconduction band (ligand hole). We are asking what are the minimal theory\ningredients needed to explain the main features of this SLE-to-DLE\nphenomenology, such as its energetic driving force, bond length changes,\npossible modifications in charge density and density of state changes. Using as\na guide the lowering of the total energy in DLE relative to SLE, we show that\ndensity functional calculations describe this phenomenology across the whole\nchemical bonding range without resort to special strong correlation effects,\nbeyond what DFT naturally contains. In particular, lower total energy\nconfigurations (DLE) naturally develop bond alternation, gaping of the metallic\nSLE state, and absence of charge ordering with ligand hole formation."
    },
    {
        "anchor": "Photothermal Engineering of Graphene Plasmons: Nanoscale photothermal sources find important applications in theranostics,\nimaging, and catalysis. In this context, graphene offers a unique suite of\noptical, electrical, and thermal properties, which we exploit to show\nself-consistent active photothermal modulation of its nanoscale response. In\nparticular, we predict the existence of plasmons confined to the optical\nlandscape tailored by continuous-wave external-light pumping of homogeneous\ngraphene. This result relies on the high electron temperatures achievable in\noptically pumped clean graphene while its lattice remains near ambient\ntemperature. Our study opens a new avenue toward the active optical control of\nthe nanophotonic response in graphene with potential application in\nphotothermal devices.",
        "positive": "Exploring Model Complexity in Machine Learned Potentials for Simulated\n  Properties: Machine learning (ML) enables the development of interatomic potentials that\npromise the accuracy of first principles methods while retaining the low cost\nand parallel efficiency of empirical potentials. While ML potentials\ntraditionally use atom-centered descriptors as inputs, different models such as\nlinear regression and neural networks can map these descriptors to atomic\nenergies and forces. This begs the question: what is the improvement in\naccuracy due to model complexity irrespective of choice of descriptors? We\ncurate three datasets to investigate this question in terms of ab initio energy\nand force errors: (1) solid and liquid silicon, (2) gallium nitride, and (3)\nthe superionic conductor LGPS. We further investigate how these errors affect\nsimulated properties with these models and verify if the improvement in fitting\nerrors corresponds to measurable improvement in property prediction. Since\nlinear and nonlinear regression models have different advantages and\ndisadvantages, the results presented herein help researchers choose models for\ntheir particular application. By assessing different models, we observe\ncorrelations between fitting quantity (e.g. atomic force) error and simulated\nproperty error with respect to ab initio values. Such observations can be\nrepeated by other researchers to determine the level of accuracy, and hence\nmodel complexity, needed for their particular systems of interest."
    },
    {
        "anchor": "Lattice dynamics of MgSiO$_3$ perovskite (bridgmanite) studied by\n  inelastic x-ray scattering and ab initio calculations: We have determined the lattice dynamics of MgSiO$_3$ perovskite (bridgmanite)\nby a combination of single-crystal inelastic x-ray scattering and ab initio\ncalculations. We observe a remarkable agreement between experiment and theory,\nand provide accurate results for phonon dispersion relations, phonon density of\nstates and the full elasticity tensor. The present work constitutes an\nimportant milestone to extend this kind of combined studies to extreme\nconditions of pressure and temperature, directly relevant for the physics and\nthe chemistry of Earth's lower mantle.",
        "positive": "Gated Silicene as a tunable source of nearly 100% spin-polarized\n  electrons: Silicene is a one-atom-thick 2D crystal of silicon with a hexagonal lattice\nstructure that is related to that of graphene but with atomic bonds that are\nbuckled rather than flat. This buckling confers advantages on silicene over\ngraphene, because it should, in principle, generate both a band gap and\npolarized spin-states that can be controlled with a perpendicular electric\nfield. Here we use first-principles calculations to show that field-gated\nsilicene possesses two gapped Dirac cones exhibiting nearly 100%\nspin-polarization, situated at the corners of the Brillouin zone. Using this\nfact, we propose a design for a silicene-based spin-filter that should enable\nthe spin-polarization of an output current to be switched electrically, without\nswitching external magnetic fields. Our quantum transport calculations indicate\nthat the proposed designs will be highly efficient (nearly 100% spin\npolarization) and robust against weak disorder and edge imperfections. We also\npropose a Y-shaped spin/valley separator that produces spin-polarized current\nat two output terminals with opposite spins."
    },
    {
        "anchor": "Kinetic Friction due to Ohm's Law Heating: Using both a recent calculation by Bruch of the damping of the motion of a\nmonolayer nitrogen film oscillating harmonically on a metallic surface due to\nOhm's law heating and a Thomas-Fermi approximation treatment of the Ohm's law\nheating mechanism, which accounts for the nonzero thickness of the surface\nregion of a metal, it is argued that this mechanism for friction is able to\naccount for recent measurements of the drop in the friction for anitrogen film\nsliding over a lead substrate as it goes below its superconducting transition\ntemperature. Bruch's calculation is also made more transparent by re-doing the\ncalculation for a film sliding at constant speed, instead of oscillating. Using\nthis treatment, it is easily shown that Bruch's calculation is equivalent to\nintegrating Boyer's solution of the problem of a charge sliding over a metallic\nsurface over the charge density of the monolayer nitrogen film.",
        "positive": "Efficient fabrication of high-density ensembles of color centers via ion\n  implantation on a hot diamond substrate: Nitrogen-Vacancy (NV) centers in diamond are promising systems for quantum\ntechnologies, including quantum metrology and sensing. A promising strategy for\nthe achievement of high sensitivity to external fields relies on the\nexploitation of large ensembles of NV centers, whose fabrication by ion\nimplantation is upper limited by the amount of radiation damage introduced in\nthe diamond lattice. In this works we demonstrate an approach to increase the\ndensity of NV centers upon the high-fluence implantation of MeV N2+ ions on a\nhot target substrate (>550 {\\deg}C). Our results show that, with respect to\nroom-temperature implantation, the high-temperature process increases the\nvacancy density threshold required for the irreversible conversion of diamond\nto a graphitic phase, thus enabling to achieve higher density ensembles.\nFurthermore, the formation efficiency of color centers was investigated on\ndiamond substrates implanted at varying temperatures with MeV N2+ and Mg+ ions\nrevealing that the formation efficiency of both NV centers and\nmagnesium-vacancy (MgV) centers increases with the implantation temperature."
    },
    {
        "anchor": "Comment on \"Gap opening in graphene by shear strain\": G. Cocco, E. Cadelano, and L. Colombo [Phys. Rev. B 81, 241412(R) (2010)]\nhave suggested that combinations of shear and uniaxial strain can be used to\nopen a band gap in graphene at much lower levels of strain than with the\napplication of unaxial strain alone. They employed a unit cell of graphene in\ntheir studies and applied the Cauchy-Born rule to model external strain.\nConsequently, an important aspect of the mechanical behavior of membranes,\nnamely buckling and wrinkling under external strain, and the attendant coupling\nwith electronic structure was ignored in their analysis. Upon doing so, the\napparent band gap that appears in the range of 15-20% shear strain under the\nCauchy-Born assumption is shown to vanish. The gapless spectrum of graphene is\nfound to persist under large shear strains as well as large combinations of\nshear and uniaxial strain.",
        "positive": "Magnetism in AV3Sb5 (A = Cs, Rb, K): Complex Landscape of the Dynamical\n  Magnetic Textures: We have investigated the dynamical magnetic properties of the V-based kagome\nstibnite compounds by combining the ab-initio calculated magnetic parameters of\na spin Hamiltonian like inter-site exchange parameters, magnetocrystalline\nanisotropy and site projected magnetic moments, with full-fledged simulations\nof atomistic spin-dynamics. Our calculations reveal that in addition to a\nferromagnetic order along the [001] direction, the system hosts a complex\nlandscape of magnetic configurations comprised of commensurate and\nincommensurate spin-spirals along the [010] direction. The presence of such\nchiral magnetic textures may be the key to solve the mystery about the origin\nof the experimentally observed inherent breaking of the C6 rotational symmetry-\nand the time-reversal symmetry."
    },
    {
        "anchor": "Sonnenstrom aus Plastik: Inspired by the success of organic light emitting diodes, organic solar cells\nhave the potential to establish interesting applications, complementing and\nenhancing the application range of inorganic systems.\n  -----\n  Durch den Erfolg organischer Leuchtdioden befl\\\"ugelt, entwickeln sich auch\norganische Solarzellen zu interessanten Anwendungen, welche das Potential\nhaben, die Anwendungsbereiche anorganischer Systeme zu erg\\\"anzen und\nerweitern.",
        "positive": "Electronic structure and direct observation of ferrimagnetism in\n  multiferroic hexagonal YbFeO3: The magnetic interaction between rare-earth and Fe ions in hexagonal\nrare-earth ferrites (h-REFeO3), may amplify the weak ferromagnetic moment on\nFe, making these materials more appealing as multiferroics. To elucidate the\ninteraction strength between the rare-earth and Fe ions as well as the magnetic\nmoment of the rare-earth ions, element specific magnetic characterization is\nneeded. Using X-ray magnetic circular dichroism, we have studied the\nferrimagnetism in h-YbFeO3 by measuring the magnetization of Fe and Yb\nseparately. The results directly show anti-alignment of magnetization of Yb and\nFe ions in h-YbFeO3 at low temperature, with an exchange field on Yb of about\n17 kOe. The magnetic moment of Yb is about 1.6 \\muB at low-temperature,\nsignificantly reduced compared with the 4.5 \\muB moment of a free Yb3+. In\naddition, the saturation magnetization of Fe in h-YbFeO3 has a sizable\nenhancement compared with that in h-LuFeO3. These findings directly demonstrate\nthat ferrimagnetic order exists in h-YbFeO3; they also account for the\nenhancement of magnetization and the reduction of coercivity in h-YbFeO3\ncompared with those in h-LuFeO3 at low temperature, suggesting an important\nrole for the rare-earth ions in tuning the multiferroic properties of h-REFeO3."
    },
    {
        "anchor": "Exploring the Electronic Potential of Effective Tight$-$Binding\n  Hamiltonians: The linear combination of atomic orbitals (LCAO) is a standard method for\nstudying solids and molecules, it is also known as the tight$-$binding (TB)\nmethod. In most of the implementations only the basis set and the coupling\nconstants are provided, without the explicit definition of kinetic and\npotential energy operators. The tight$-$binding scheme is, nonetheless, capable\nof providing an accurate description of properties such as the electronic bands\nand elastic constants for many materials. However, for some applications, the\nknowledge of the underlying electronic potential associated with the\ntight$-$binding hamiltonian might be important to guarantee that the actual\nphysics is preserved by the semiempirical scheme. In this work the electronic\npotentials that arise from the use of tight$-$binding effective hamiltonians it\nis explored. The formalism is applied to the extended H\\\"{u}ckel\ntight$-$binding (EHTB) hamiltonian, which is a two$-$center Slater$-$Koster\napproach that makes explicit use of the overlap matrix.",
        "positive": "Structural, elastic, thermal, and electronic response of\n  small-molecule-loaded metal organic framework materials: We combine infrared spectroscopy, nano-indentation measurements, and \\emph{ab\ninitio} simulations to study the evolution of structural, elastic, thermal, and\nelectronic responses of the metal organic framework MOF-74-Zn when loaded with\nH$_2$, CO$_2$, CH$_4$, and H$_2$O. We find that the molecular adsorption in\nthis MOF triggers remarkable responses in all of these properties of the host\nmaterial, with specific signatures for each of the guest molecules. With this\ncomprehensive study we are able to clarify and correlate the underlying\nmechanisms regulating these responses with changes of the physical and chemical\nenvironment. Our findings suggest that metal organic framework materials in\ngeneral, and MOF-74-Zn in particular, can be very promising materials for novel\ntransducers and sensor applications, including highly selective small-molecule\ndetection in gas mixtures."
    },
    {
        "anchor": "The onset of void coalescence during dynamic fracture of ductile metals: Molecular dynamics simulations in three-dimensional copper have been\nperformed to quantify the void coalescence process leading to fracture. The\ncorrelated growth of the voids during their linking is investigated both in\nterms of the onset of coalescence and the ensuing dynamical interactions\nthrough the rate of reduction of the distance between the voids and the\ndirectional growth of the voids. The critical inter-void ligament distance\nmarking the onset of coalescence is shown to be approximately one void radius\nin both measures.",
        "positive": "Modeling epitaxial film growth of C$_{60}$ revisited: Epitaxial films evolve on time and length scales that are inaccessible to\natomistic computer simulation methods like molecular dynamics (MD). To\nnumerically predict properties for such systems, a common strategy is to employ\nkinetic Monte Carlo (KMC) simulations, for which one needs to know the\ntransition rates of the involved elementary steps. The main challenge is thus\nto formulate a consistent model for the set of transition rates and to\ndetermine its parameters. Here we revisit a well-studied model system, the\nepitaxial film growth of the fullerene C$_{60}$ on an ordered C$_{60}$\nsubstrate(111). We implement a systematic multiscale approach in which we\ndetermine transition rates through MD simulations of specifically designed\ninitial configurations. These rates follow Arrhenius' law, from which we\nextract energy barriers and attempt rates. We discuss the issue of detailed\nbalance for the resulting rates. Finally, we study the morphology of subatomic\nand multilayer film growth and compare simulation results to experiments. Our\nmodel enables further studies on multi-layer growth processes of C$_{60}$ on\nother substrates."
    },
    {
        "anchor": "Investigation of Long Monolayer Graphene Ribbons grown on Graphite\n  Capped 6H-SiC (000-1): We present an investigation of large, isolated, graphene ribbons grown on the\nC-face of on-axis semi-insulating 6H-SiC wafers. Using a graphite cap to cover\nthe SiC sample, we modify the desorption of the Si species during the Si\nsublimation process. This results in a better control of the growth kinetics,\nyielding very long (about 300 microns long, 5 microns wide), homogeneous\nmonolayer graphene ribbons. These ribbons fully occupy unusually large terraces\non the step bunched SiC surface, as shown by AFM, optical microscopy and SEM.\nRaman spectrometry indicates that the thermal stress has been partially relaxed\nby wrinkles formation, visible in AFM images. In addition, we show that despite\nthe low optical absorption of graphene, optical differential transmission can\nbe successfully used to prove the monolayer character of the ribbons.",
        "positive": "Nonzero macroscopic magnetization in half-metallic antiferromagnets at\n  finite temperatures: Combining density-functional theory calculations with many-body\nGreen's-function technique, we reveal that the macroscopic magnetization in\nhalf-metallic antiferromagnets does not vanish at finite temperature as for the\nT=0 limit. This anomalous behavior stems from the inequivalent magnetic\nsublattices which lead to different intrasublattice exchange interactions. As a\nconsequence, the spin fluctuations suppress the magnetic order of the\nsublattices in a different way leading to a ferrimagnetic state at finite\ntemperatures. Computational results are presented for the half-metallic\nantiferromagnetic CrMnZ (Z=P,As,Sb) semi-Heusler compounds."
    },
    {
        "anchor": "Atomic structure of amorphous SiN: combining Car-Parrinello and\n  Born-Oppenheimer first-principles molecular dynamics: First-principles molecular dynamics is employed to describe the atomic\nstructure of amorphous SiN, a non-stoichiometric compound belonging to the\nSi$_x$N$_{y}$ family. To produce the amorphous state via the cooling of the\nliquid, both the Car-Parrinello and the Born-Oppenheimer approaches are\nexploited to obtain a system featuring sizeable atomic mobility. At high\ntemperatures, due to the peculiar electronic structure of SiN, exhibiting gap\nclosing effects, the Car-Parrinello methodology could not be followed since\nnon-adiabatic effects involving the ionic and electronic degrees of freedom do\noccur. This shortcoming was surmounted by resorting to the Born-Oppenheimer\napproach allowing to achieve significant ionic diffusion at $T$= 2500 K. From\nthis highly diffusive sample, an amorphous state at room temperature was\nobtained with a quenching rate of 10 K/ps. Four different models were created,\ndiffering by their sizes and the thermal cycles. We found that the subnetwork\nof atoms N has the same environment than in the stoichiometric material\nSi$_3$N$_4$ since N is mostly threefold coordinated with Si. Si atoms can also\nbe found coordinated to four N atoms as in Si$_3$N$_4$, but a substantial\nfraction of them forms homopolar bonds with one, two, three and even four Si.\nOur results are not too dissimilar from former models available in the\nlitterature but they feature a higher statistical accuracy and refer more\nprecisely to room temperature as the reference thermodynamical condition for\nthe analysis of the structure in the amorphous state.",
        "positive": "Terahertz spectra databases require crystallographic information: Although the sensitivity of THz spectra to the crystal form of the sample\nbeing analysed makes it an ideal tool for differentiating polymorphic forms of\ncrystalline materials, the lack of adequate knowledge about the THz response to\nvarious materials often results in misinterpretations. The inclusion of\nstructural information in THz spectral databases of crystalline substances is\ntherefore suggested."
    },
    {
        "anchor": "Low-temperature criticality of martensitic transformations of Cu\n  nanoprecipitates in \u03b1-Fe: Nanoprecipitates form during nucleation of multiphase equilibria in phase\nsegregating multicomponent systems. In spite of their ubiquity, their\nsize-dependent physical chemistry, in particular at the boundary between phases\nwith incompatible topologies, is still rather arcane. Here we use extensive\natomistic simulations to map out the size-temperature phase diagram of Cu\nnanoprecipitates in \\alpha-Fe. The growing precipitates undergo martensitic\ntransformations from the body-centered cubic (BCC) phase to multiply-twinned 9R\nstructures. At high temperatures, the transitions exhibit strong first-order\ncharacter and prominent hysteresis. Upon cooling the discontinuities become\nless pronounced and the transitions occur at ever smaller cluster sizes. Below\n300 K the hysteresis vanishes while the transition remains discontinuous with a\nfinite but diminishing latent heat. This unusual size-temperature phase diagram\nresults from the entropy generated by the soft modes of the BCC-Cu phase, which\nare stabilized through confinement by the \\alpha-Fe lattice.",
        "positive": "Effective complex permittivity tensor of a periodic array of cylinders: We determine the effective complex permittivity of a two-dimensional\ncomposite, consisting of an arbitrary doubly periodic array of identical\ncircular cylinders in a homogeneous matrix, and whose dielectric properties are\ncomplex-valued. Efficient formulas are provided to determine the effective\ncomplex permittivity tensor which are in excellent agreement with numerical\ncalculations. We also show that in contrast to the real-valued case, the real\nand imaginary parts of the effective complex-valued tensor can exhibit\nnon-monotonic behavior as functions of volume fraction of cylinders, and can be\neither greater or less than that of the constituents."
    },
    {
        "anchor": "Coulomb blockade in electron transport through a C$_{60}$ molecule from\n  first principles: We present results of spin-unrestricted first-principles quantum transport\nfor a gated C$_{60}$ molecule weakly contacted to Al electrodes, making\nemphasis on the role played by the electronic localization and the spin degree\nof freedom. As expected, the conductance presents a series of peaks as a\nfunction of a gate voltage, demonstrating that transport in the Coulomb\nblockade regime can be properly treated within a first-principles scheme. A\nwell-known manifestation of the interplay between Coulomb interaction and the\nspin degree of freedom in atoms and molecules, the Hund 's rule, determines the\nsequence of conductance peaks.",
        "positive": "Photoinduced C70 radical anions in polymer:fullerene blends: Photoinduced polarons in solid films of polymer-fullerene blends were studied\nby photoluminescence (PL), photoinduced absorption (PIA) and electron spin\nresonance (ESR). The donor materials used were P3HT and MEH-PPV. As acceptors\nwe employed PC60BM as reference and various soluble C70-derivates: PC70BM, two\ndifferent diphenylmethano-[70]fullerene oligoether (C70-DPM-OE) and two dimers,\nC70-C70 and C60-C70. Blend films containing C70 revealed characteristic\nspectroscopic signatures not seen with C60. Light-induced ESR showed signals at\ng\\geq2.005, assigned to an electron localized on the C70 cage. The formation of\nC70 radical anions also leads to a subgap PIA band at 0.92 eV, hidden in the\nspectra of C70-based P3HT and MEH-PPV blends, which allows for more exact\nstudies of charge separated states in conjugated polymer:C70 blends."
    },
    {
        "anchor": "Probing phonon dynamics with multi-dimensional high harmonic carrier\n  envelope phase spectroscopy: We explore pump-probe high harmonic generation (HHG) from monolayer\nhexagonal-Boron-Nitride, where a terahertz pump excites coherent optical\nphonons that are subsequently probed by an intense infrared pulse that drives\nHHG. We find, through state-of-the-art ab-initio calculations, that the\nstructure of the emission spectrum is attenuated by the presence of coherent\nphonons, and is no longer comprised of discrete harmonic orders, but rather of\na continuous emission in the plateau region. The HHG yield strongly oscillates\nas a function of the pump-probe delay, corresponding to ultrafast changes in\nthe lattice such as bond compression or stretching. We further show that in the\nregime where the excited phonon period and the pulse duration are of the same\norder of magnitude, the HHG process becomes sensitive to the\ncarrier-envelope-phase (CEP) of the driving field, even though the pulse\nduration is so long that no such sensitivity is observed in the absence of\ncoherent phonons. The degree of CEP sensitivity vs. pump-probe delay is shown\nto be a highly selective measure for instantaneous structural changes in the\nlattice, providing a new approach for ultrafast multi-dimensional\nHHG-spectroscopy. Remarkably, the obtained temporal resolution for phonon\ndynamics is ~1 femtosecond, which is much shorter than the probe pulse duration\nbecause of the inherent sub-cycle contrast mechanism. Our work paves the way\ntowards novel routes of probing phonons and ultrafast material structural\nchanges and provides a mechanism for controlling the high harmonic response.",
        "positive": "Charge writing at the LaAlO3/SrTiO3 surface: Biased conducting-tip atomic force microscopy (AFM) has been shown to write\nand erase nanoscale metallic lines at the LaAlO3/SrTiO3 interface. Using\nvarious AFM modes, we show the mechanism of conductivity switching is the\nwriting of surface charge. These charges are stably deposited on a wide range\nof LaAlO3 thicknesses, including bulk crystals. A strong asymmetry with writing\npolarity was found for 1 and 2 unit cells of LaAlO3, providing experimental\nevidence for a theoretically predicted built-in potential."
    },
    {
        "anchor": "Observation of topological valley modes in an elastic hexagonal lattice: We report on the experimental observation of topologically protected edge\nwaves in a two-dimensional elastic hexagonal lattice. The lattice is designed\nto feature K point Dirac cones that are well separated from the other numerous\nelastic wave modes characterizing this continuous structure. We exploit the\narrangement of localized masses at the nodes to break mirror symmetry at the\nunit cell level, which opens a frequency bandgap. This produces a non-trivial\nband structure that supports topologically protected edge states along the\ninterface between two realizations of the lattice obtained through mirror\nsymmetry. Detailed numerical models support the investigations of the\noccurrence of the edge states, while their existence is verified through\nfull-field experimental measurements. The test results show the confinement of\nthe topologically protected edge states along pre-defined interfaces and\nillustrate the lack of significant backscattering at sharp corners. Experiments\nconducted on a trivial waveguide in an otherwise uniformly periodic lattice\nreveal the inability of a perturbation to propagate and its sensitivity to\nbackscattering, which suggests the superior waveguiding performance of the\nclass of non-trivial interfaces investigated herein.",
        "positive": "Gapped nodal planes drive a large topological Nernst effect in a chiral\n  lattice antiferromagnet: The electronic structure of compensated antiferromagnets (CAF) has drawn\nattention for its ability to create large responses, reminiscent of\nferromagnets and suitable for data storage and readout, despite (nearly)\nnet-zero spontaneous magnetization. Many of the striking experimental\nsignatures predicted for CAF, such as giant thermoelectric Nernst effects, are\nenhanced when two or more electronic bands are nearly degenerate in vicinity of\nthe Fermi energy. Here, we use thermoelectric and electric transport\nexperiments to study the electronic structure of the layered, chiral metal\nCoNb3S6 in its all-in-all-out CAF ground state and report near-degeneracies of\nelectron bands at the upper and lower boundaries of the first Brillouin zone.\nConsidering non-symmorphic spin-space group symmetries in the non-relativistic\napproximation for the ordered phase, these near-degeneracies are approximately\nprotected by a lattice translation combined with spin rotation, and are\nvestiges of nodal planes enforced by a screw axis symmetry in the paramagnetic\nstate. Hot spots of emergent, or fictitious, magnetic fields are formed at the\nslightly gapped nodal plane, generating the spontaneous Hall and Nernst effects\nin this CAF. Taking into account more than six hundred Wannier orbitals, our\nmodel quantitatively reproduces the observed spontaneous Nernst effect,\nemphasizes the role of proximate symmetries in the emergent responses of CAF,\nand demonstrates the promise of ab-initio search for functional responses in a\nwide class of materials with reconstructed unit cells due to spin or charge\norder."
    },
    {
        "anchor": "Three-dimensional carbon Archimedean lattices for high-performance\n  electromechanical actuators: We propose three-dimensional carbon (3D-C) structures based on the\nArchimedean lattices (ALs) by combining $sp^2$ bonding in the polygon edges and\n$sp^3$ bonding in the polygon vertices. By first-principles calculations, four\ntypes of 3D-C ALs: (4, $8^2$), (3, $12^2$), ($6^3$), and ($4^4$) 3D-Cs are\npredicted to be stable both dynamically and mechanically among 11 possible ALs.\nDepending on the index of ALs, the 3D-C ALs show distinctive electronic\nproperties: the (4, $8^2$) 3D-C is an indirect bandgap semiconductor, the (3,\n$12^2$) 3D-C is semimetal, while the ($6^3$) and ($4^4$) 3D-Cs are metals.\nConsidering the structural deformation due to the changes in their electronic\nenergy bands, we discuss the electromechanical properties of the 3D-C ALs as a\nfunction of charge doping. We find a semiconductor-to-metal and\nsemimetallic-to-semiconductor transitions in the (4, $8^2$) and (3, $12^2$)\n3D-Cs as a function of charge doping, respectively. Moreover, the (3, $12^2$)\n3D-C exhibits a $sp^2$-$sp^3$ phase transformation at high charge doping, which\nleads to a huge 30% irreversible strain, while the reversible strain in the (4,\n$8^2$) 3D-C is up to 9%, and thus they are quite promising for\nelectromechanical actuators.",
        "positive": "The role of ionization fraction on the surface roughness, density and\n  interface mixing of the films deposited by thermal evaporation, dc magnetron\n  sputtering and HiPIMS: An atomistic simulation: We explore the effect of ionization fraction on the epitaxial growth of Cu\nfilm on Cu (111) substrate at room temperature. We compare thermal evaporation,\ndc magnetron sputtering (dcMS) and high power impulse magnetron sputtering\n(HiPIMS). Three deposition conditions i.e. fully neutral, 50% ionized and 100%\nionized flux were considered as thermal evaporation, dcMS and HiPIMS,\nrespectively, for ~20000 adatoms. It is shown that higher ionization fraction\nof the deposition flux leads to smoother surfaces by two major mechanisms i.e.\ndecreasing clustering in the vapor phase and bi-collision of high energy ions\nat the film surface. The bi-collision event consists of local amorphization\nwhich fills the gaps between islands followed by crystallization due to\nsecondary collisions. We found bi-collision events to be very important to\nprevent island growth to become dominant and increase the surface roughness.\nRegardless of the deposition method, epitaxial Cu thin films suffer from\nstacking fault areas (twin boundaries) in agreement with recent experimental\nresults. In addition, HiPIMS deposition presents considerable interface mixing\nwhile it is negligible in thermal evaporation and dcMS deposition, those\npresent less adhesion accordingly."
    },
    {
        "anchor": "Delicate Ferromagnetism in MnBi$_6$Te$_{10}$: Tailoring magnetic orders in topological insulators is critical to the\nrealization of topological quantum phenomena. An outstanding challenge is to\nfind a material where atomic defects lead to tunable magnetic orders while\nmaintaining a nontrivial topology. Here, by combining magnetization\nmeasurements, angle-resolved photoemission spectroscopy, and transmission\nelectron microscopy, we reveal disorder-enabled, tunable magnetic ground states\nin MnBi$_6$Te$_{10}$. In the ferromagnetic phase, an energy gap of 15 meV is\nresolved at the Dirac point on the MnBi$_2$Te$_4$ termination. In contrast,\nantiferromagnetic MnBi$_6$Te$_{10}$ exhibits gapless topological surface states\non all terminations. Transmission electron microscopy and magnetization\nmeasurements reveal substantial Mn vacancies and Mn migration in ferromagnetic\nMnBi$_6$Te$_{10}$. We provide a conceptual framework where a cooperative\ninterplay of these defects drives a delicate change of overall magnetic ground\nstate energies, and leads to tunable magnetic topological orders. Our work\nprovides a clear pathway for nanoscale defect-engineering towards the\nrealization of topological quantum phases.",
        "positive": "The Potential Energy Hotspot: Effects from Impact Velocity, Defect\n  Geometry, and Crystallographic Orientation: In energetic materials, the localization of energy into \"hotspots\" when a\nshock wave interacts with the material's microstructure is known to dictate the\ninitiation of chemical reactions and detonation. Recent results have shown\nthat, following the shock-induced collapse of pores with circular\ncross-sections, more energy is localized as internal potential energy (PE) than\ncan be inferred from the kinetic energy (KE) distribution. This leads to a\ncomplex thermo-mechanical state that is typically overlooked. The mechanisms\nassociated with pore collapse and hotspot formation and the resulting energy\nlocalization are known to be highly dependent on material properties,\nespecially its ability to deform plastically and alleviate strain energy, as\nwell as the size and shape of the pore. Therefore, we use molecular dynamics\nsimulations to characterize shock-induced pore collapse and the subsequent\nformation of hotspots in TATB, a highly anisotropic molecular crystal, for\nvarious defect shapes, shock strengths and crystallographic orientations. We\nfind that the the localization of energy as PE is consistently higher and its\nextent larger than as localized as KE. A detailed analysis of the MD\ntrajectories reveal the underlying molecular process that govern the effect of\norientation and pore shape on the resulting hotspots. We find that the regions\nof highest PE for a given KE relate to not the impact front of the collapse,\nbut the areas of maximum plastic deformation, while KE is maximized at the\npoint of impact. A comparison with previous results in HMX reveal less energy\nlocalization in TATB which could be a contributing factor to its insensitivity."
    },
    {
        "anchor": "Non-adiabatic effects and exciton-like states during insulator-to-metal\n  transition in warm dense hydrogen: Transition of molecular hydrogen to atomic ionized state with increase of\ntemperature and pressure poses still unresolved problems for experimental\nmethods and theory. Here we analyze the dynamics of this transition and show\nits nonequilibrium non-adiabatic character overlooked in both interpreting\nexperimental data and in theoretical models. The non-adiabatic mechanism\nexplains the strong isotopic effect [Zaghoo, Husband, and Silvera, Phys. Rev. B\n98, 104102 (2018)] and the large latent heat [Houtput, Tempere, and Silvera,\nPhys. Rev. B 100, 134106 (2019)] reported recently. We demonstrate the\npossibility of formation of intermediate exciton-like molecular states at\nheating of molecular hydrogen that can explain puzzling experimental data on\nreflectivity and conductivity during the insulator-to-metal transition.",
        "positive": "Constrained non-collinear magnetism in disordered Fe and Fe-Cr alloys: The development of quantitative models for radiation damage effects in iron,\niron alloys and steels, particularly for the high temperature properties of the\nalloys, requires understanding of magnetic interactions, which control the\nphase stability of ferritic-martensitic, ferritic, and austenitic steels. In\nthis work, disordered magnetic configurations of pure iron and Fe-Cr alloys are\ninvestigated using Density Functional Theory (DFT) formalism, in the form of\nconstrained non-collinear magnetic calculations, with the objective of creating\na database of atomic magnetic moments and forces acting between the atoms. From\na given disordered atomic configuration of either pure Fe or Fe-Cr alloy, a\npenalty contribution to the usual spin-polarized DFT total energy has been\ncalculated by constraining the magnitude and direction of magnetic moments. An\nextensive database of non-collinear magnetic moment and force components for\nvarious atomic configurations has been generated and used for interpolating the\nspatially-dependent magnetic interaction parameters, for applications in\nlarge-scale spin-lattice dynamics and magnetic Monte-Carlo simulations."
    },
    {
        "anchor": "First-principles Study on Formation of LPSO Structures for Ternary\n  Alloys Revisited from Short-range Order: We investigate the formation of long-period stacking ordered (LPSO) structure\nfor Mg-Y-Zn ternary alloys based on the short-range order (SRO) tendency of\nenergetically competitive disordered phases. We find that unisotropic SRO\ntendencies for structures with stacking faults cannot be simply interpreted by\narithmetic average of SRO for constituent fcc and hcp stackings, indicating\nthat the SRO should be significantly affected by periodically-introduced\nstacking faults. We also find that SRO for neighboring Y-Zn pair, which should\nhave positive sign to form specific L12 type cluster found in LPSO, is strongly\naffected by the distance between stacking faults: e.g., five atomic layer\ndistance does not prefer in-plane Y-Zn pair, while seven atomic layer distance\nprefer both in- and inter-plane Y-Zn pair. These facts strongly indicate that\nordering tendency for the Mg-Y-Zn alloy is significantly dominated by the\nstacking faults as well as their periodicity. We also systematically\ninvestigate correlation between SRO for other Mg-RE-Zn (RE = La, Tb, Dy, Ho,\nEr) alloys and the physical property of RE elements. We find that while SRO for\nRE-Zn pair does not show effective correlation with atomic radius, it has\nstrong quadratic correlation with atomic radius considering unisotoropy along\nin- and inter-plane directions.",
        "positive": "First-principles calculations of the surface states of doped and alloyed\n  topological materials via band unfolding method: One of the most remarkable characteristics of topological materials is that\nthey have special surface states, which are determined by the topological\nproperties of their bulk materials. The angle resolved photoemission\nspectroscopy (ARPES) is a powerful tool to explore the surface states, which\nallows to further investigate the topological phase transitions. However, it is\nvery difficult to compare the first-principle calculated band structures to the\nARPES results,when the systems are doped or alloyed, because the band\nstructures are heavily folded.We develop an efficient band unfolding method\nbased on numerical atomic orbitals (NAOs). We apply this method to study the\nsurface states of the non-magnetically and magnetically doped topological\ninsulators Bi$_2$Se$_3$ and the topological crystalline insulators\nPb$_{1-x}$Sn$_{x}$Te."
    },
    {
        "anchor": "Probing ultrafast symmetry breaking in photo-stimulated matter: The nature of a phase transition is inherently connected to the changes in\nthe crystalline symmtry, which is typically probed by elastic or inelastic\nscattering with neutrons, electrons or photons. When such a phase transition is\nstimulated by light or other sudden perturbations the solid evolves along a\nnon-equilibrium pathway of which the underlying physics is poorly understood.\nHere we use picosecond Raman scattering to study the photo-induced ultrafast\ndynamics in Peierls distorted Antimony. We find evidence for an ultrafast\nnon-thermal reversible structural phase transition. Most surprisingly, we find\nevidence that this transition evolves toward a lower symmetry, in contrast to\nthe commonly accepted rhombohedral-to-simple cubic transition path. Our study\ndemonstrates the feasibility of ultrafast Raman scattering symmetry analysis of\nphoto-induced non-thermal transient phases.",
        "positive": "Modulation of the Work Function by the Atomic Structure of Strong\n  Organic Electron Acceptors on H-Si(111): Advances in hybrid organic/inorganic architectures for optoelectronics can be\nachieved by understanding how the atomic and electronic degrees of freedom\ncooperate or compete to yield the desired functional properties. Here we show\nhow work-function changes are modulated by the structure of the organic\ncomponents in model hybrid systems. We consider two cyano-quinodimethane\nderivatives (F4-TCNQ and F6-TCNNQ), which are strong electron-acceptor\nmolecules, adsorbed on H-Si(111). From systematic structure searches employing\nrange-separated hybrid HSE06 functional including many body van der Waals\ncontributions, we predict that despite their similar composition, these\nmolecules adsorb with significantly different densely-packed geometries in the\nfirst layer, due to strong intermolecular interaction. F6-TCNNQ shows a much\nstronger intralayer interaction (primarily due to van der Waals contributions)\nthan F4-TCNQ in multilayered structures. The densely-packed geometries induce a\nlarge interface-charge rearrangement that result in a work-function increase of\n1.11 and 1.76 eV for F4-TCNQ and F6-TCNNQ, respectively. Nuclear fluctuations\nat room temperature produce a wide distribution of work-function values, well\nmodeled by a normal distribution with {\\sigma}=0.17 eV. We corroborate our\nfindings with experimental evidence of pronounced island formation for F6-TCNNQ\non H-Si(111) and with the agreement of trends between predicted and measured\nwork-function changes."
    },
    {
        "anchor": "Hierarchy of adhesion forces in patterns of photoreactive surface layers: Precise control of surface properties including electrical characteristics,\nwettability, and friction is a prerequisite for manufacturing modern organic\nelectronic devices. The successful combination of bottom up approaches for\naligning and orienting the molecules and top down techniques to structure the\nsubstrate on the nano and micrometer scale allows the cost efficient\nfabrication and integration of future organic light emitting diodes and organic\nthin film transistors. One possibility for the top down patterning of a surface\nis to utilize different surface free energies or wetting properties of a\nfunctional group. Here, we used friction force microscopy (FFM) to reveal\nchemical patterns inscribed by a photolithographic process into a\nphotosensitive surface layer. FFM allowed the simultaneous visualization of at\nleast three different chemical surface terminations. The underlying mechanism\nis related to changes in the chemical interaction between probe and film\nsurface.",
        "positive": "Tailoring magnetism of nanographenes via tip-controlled dehydrogenation: Atomically precise graphene nanoflakes, called nanographenes, have emerged as\na promising platform to realize carbon magnetism. Their ground state spin\nconfiguration can be anticipated by Ovchinnikov-Lieb rules based on the\nmismatch of {\\pi}-electrons from two sublattices. While rational geometrical\ndesign achieves specific spin configurations, further direct control over the\n{\\pi}-electrons offers a desirable extension for efficient spin manipulations\nand potential quantum device operations. To this end, we apply a site-specific\ndehydrogenation using a scanning tunneling microscope tip to nanographenes\ndeposited on a Au(111) substrate, which shows the capability of precisely\ntailoring the underlying {\\pi}-electron system and therefore efficiently\nmanipulating their magnetism. Through first-principles calculations and\ntight-binding mean-field-Hubbard modelling, we demonstrate that the\ndehydrogenation-induced Au-C bond formation along with the resulting\nhybridization between frontier {\\pi}-orbitals and Au substrate states\neffectively eliminate the unpaired {\\pi}-electron. Our results establish an\nefficient technique for controlling the magnetism of nanographenes."
    },
    {
        "anchor": "Anomalous electric conductions in KSbO3-type metallic rhenium oxides: Single crystals of KSbO3-type rhenium oxides, La4Re6O$19, Pb6Re6O19, Sr2Re3O9\nand Bi3Re3O11, were synthesized by a hydrothermal method. Their crystal\nstructures can be regarded as a network of three-dimensional orthogonal-dimer\nlattice of edge-shared ReO6 octahedra. All of them exhibit small magnitude of\nPauli paramagnetism, indicating metallic electronic states without strong\nelectron correlations. The resistivity of these rhenates, except Bi3Re3O11,\nhave a temperature dependence of $rho(T)=\\rho_{0}+AT^{n}$ $(n \\approx 1.6)$ in\na wide temperature range between 5 K and 300 K, which is extraordinary for\nthree-dimensional metals without strong electron correlations. The resistivity\nof Bi3Re3O11 shows an anomaly around at 50 K, where the magnetic susceptibility\nalso detects a deviation from ordinary Pauli paramagnetism.",
        "positive": "On the Quality of Uncertainty Estimates from Neural Network Potential\n  Ensembles: Neural network potentials (NNPs) combine the computational efficiency of\nclassical interatomic potentials with the high accuracy and flexibility of the\nab initio methods used to create the training set, but can also result in\nunphysical predictions when employed outside their training set distribution.\nEstimating the epistemic uncertainty of an NNP is required in active learning\nor on-the-fly generation of potentials. Inspired from their use in other\nmachine-learning applications, NNP ensembles have been used for uncertainty\nprediction in several studies, with the caveat that ensembles do not provide a\nrigorous Bayesian estimate of the uncertainty. To test whether NNP ensembles\nprovide accurate uncertainty estimates, we train such ensembles in four\ndifferent case studies, and compare the predicted uncertainty with the errors\non out-of-distribution validation sets. Our results indicate that NNP ensembles\nare often overconfident, underestimating the uncertainty of the model, and\nrequire to be calibrated for each system and architecture. We also provide\nevidence that Bayesian NNPs, obtained by sampling the posterior distribution of\nthe model parameters using Monte-Carlo techniques, can provide better\nuncertainty estimates."
    },
    {
        "anchor": "Direct visualization of antiferroelectric switching dynamics via\n  electrocaloric imaging: The large electrocaloric coupling in PbZrO3 allows using high-speed infrared\nimaging to visualize antiferroelectric switching dynamics via the associated\ntemperature change. We find that in ceramic samples of homogeneous temperature\nand thickness, switching is nucleation-limited and fast, with devices\nresponding in the milisecond range. By introducing gradients of thickness,\nhowever, it is possible to change the dynamics from nucleation-limited to\npropagation-limited, whereby a single phase boundary sweeps across the sample\nlike a cold front, at a speed of c.a. 20 cm/s. Additionally, introducing\nthermostatic temperature differences between two sides of the sample enables\nthe simultaneous generation of a negative electrocaloric effect on one side and\na positive one on the other, yielding a Janus-like electrocaloric response.",
        "positive": "Determination of localized conduction band-tail states distribution in\n  single phase undoped microcrystalline silicon: We report on the phototransport properties of microstructurally well\ncharacterized plasma deposited highly crystallized microcrystalline silicon\nfilms. The steady state photoconductivity was measured on a wide\nmicrostructural variety of single-phase undoped microcrystalline silicon films\nas a function of temperature and light intensity. The band-tail parameter (kTc)\nwas calculated from the photoconductivity light intensity exponent values at\ndifferent temperatures for a range of quasi-Fermi energies. The localized tail\nstates distribution in the vicinity of conduction band edge of microcrystalline\nsilicon was estimated using the values of kTc. Our study shows that\nmicrocrystalline silicon films possessing dissimilar microstructural attributes\nexhibit different phototransport behaviors, which are linked to different\nfeatures of the density of states maps of the material."
    },
    {
        "anchor": "Adhesion and material transfer between contacting Al and TiN surfaces\n  from first principles: A series of density functional theory (DFT) simulations was performed to\ninvestigate the approach, contact, and subsequent separation of two atomically\nflat surfaces consisting of different materials. Aluminum (Al) and titanium\nnitride (TiN) slabs were chosen as a model system representing a metal-ceramic\ninterface and the interaction between soft and hard materials. The approach and\nseparation were simulated by moving one slab in discrete steps normal to the\nsurfaces allowing for electronic and atomic relaxations after each step.\nVarious configurations were analyzed by considering (001), (011), and (111)\nsurfaces as well as several lateral arrangements of these surfaces at the\ninterface. Several tests were conducted on the computational setup, for\nexample, by changing the system size or using different approximations for the\nexchange correlation functional. The performed simulations revealed the\ninfluences of these aspects on adhesion, equilibrium distance, and material\ntransfer. These interfacial properties depend sensitively on the chosen\nconfiguration due to distinct bond situations. Material transfer, in\nparticular, was observed if the absolute value of the adhesion energy for a\ngiven configuration is larger than the energy cost to remove surface layers.\nThis result was found to be independent of the employed exchange correlation\nfunctional. Furthermore, it was shown that a simple comparison of the surface\nenergies of the slabs is not sufficient to predict the occurrence of material\ntransfer.",
        "positive": "Energy efficient spark plasma sintering: Breaking the threshold of large\n  dimension tooling energy consumption: An energy efficient spark plasma sintering method enabling the densification\nof large size samples assisted by very low electric current levels is\ndeveloped. In this method, the electric current is concentrated in the graphite\nfoils around the sample. High energy dissipation is then achieved in this area\nenabling the heating and full densification of large (alumina) parts ({{\\O}} 40\nmm) at relatively low currents (800 A). The electrothermal mechanical\nsimulation reveals that the electric current needed to heat the large samples\nis 70 % lower in the energy efficient configuration compared to the traditional\nconfiguration. The presence of thermal and densification gradients is also\nrevealed for the larger size samples. Potential solutions for this problem are\ndiscussed. The experiments confirm the possibility of full densification (96-99\n%) of large alumina samples. This approach allows using small (and low cost)\nSPS devices (generally limited to 10-15 mm samples) for large size samples\n(40-50 mm). The developed technique enables also an optimized energy\nconsumption by large scale SPS systems."
    },
    {
        "anchor": "Fractal space frames and metamaterials for high mechanical efficiency: A solid slender beam of length $L$, made from a material of Young's modulus\n$Y$ and subject to a gentle compressive force $F$, requires a volume of\nmaterial proportional to $L^{3}f^{1/2}$ [where $f\\equiv F/(YL^{2})\\ll 1$] in\norder to be stable against Euler buckling. By constructing a hierarchical space\nframe, we are able to systematically change the scaling of required material\nwith $f$ so that it is proportional to $L^{3}f^{(G+1)/(G+2)}$, through changing\nthe number of hierarchical levels $G$ present in the structure. Based on simple\nchoices for the geometry of the space frames, we provide expressions specifying\nin detail the optimal structures (in this class) for different values of the\nloading parameter $f$. These structures may then be used to create effective\nmaterials which are elastically isotropic and have the combination of low\ndensity and high crush strength. Such a material could be used to make\nlight-weight components of arbitrary shape.",
        "positive": "Interface-Confined Doubly Anisotropic Oxidation of Two-Dimensional MoS2: Despite their importance, chemical reactions confined in a low dimensional\nspace are elusive and experimentally intractable. In this work, we report\ndoubly anisotropic, in-plane and out-of-plane, oxidation reactions of\ntwo-dimensional crystals, by resolving interface-confined thermal oxidation of\na single and multilayer MoS2 supported on silica substrates from their\nconventional surface reaction. Using optical second-harmonic generation\nspectroscopy of artificially stacked multilayers, we directly proved that\ncrystallographically oriented triangular oxides (TOs) were formed in the\nbottommost layer while triangular etch pits (TEs) were generated in the topmost\nlayer and that both structures were terminated with zigzag edges. The formation\nof the Mo oxide layer at the interface demonstrates that O2 diffuses\nefficiently through the van der Waals (vdW) gap but not MoO3, which would\notherwise sublime. The fact that TOs are several times larger than TEs\nindicates that oxidation is greatly enhanced when MoS2 is in direct contact\nwith silica substrates, which suggests a catalytic effect. This study indicates\nthat the vdW-bonded interfaces are essentially open to mass transport and can\nserve as a model system for investigating chemistry in low dimensional spaces."
    },
    {
        "anchor": "Direct Observation of Re-entrant Multiferroic CuO at High Pressures: We have carried out a detailed experimental investigation on CuO using\ndielectric constant, ac resistance, Raman spectroscopy and X-ray diffraction\nmeasurements at high pressures and room temperature. Both dielectric constant\nand dielectric loss show an anomalous peak in the pressure range 3.4-4 GPa\nindicating a ferroelectric transition. Raman studies show anomalous behaviour\nof the Ag mode with a slope change in the mode frequency and a minimum in the\nmode FWHM at 3.4 GPa indicating a strong spin phonon coupling along [1 0 -1]\ndirection. A step like behaviour in the intensity of the Ag mode is observed at\n3.4 GPa, indicating a change in the polarization of the mode. A maximum in the\nintensity of (2,0,-2)Bragg peak at 3.4 GPa points the occurrence of critical\nscattering due to emergence of magnetic exchange interaction. All our\nexperimental evidences show to the presence of re-entrant type-II multiferroic\nbehaviour in CuO at about 4 GPa.",
        "positive": "Planar designs for electromagnetically induced transparency in\n  metamaterials: We present a planar design of a metamaterial exhibiting electromagnetically\ninduced transparency that is amenable to experimental verification in the\nmicrowave frequency band. The design is based on the coupling of a split-ring\nresonator with a cut-wire in the same plane. We investigate the sensitivity of\nthe parameters of the transmission window on the coupling strength and on the\ncircuit elements of the individual resonators, and we interpret the results in\nterms of two linearly coupled Lorentzian resonators. Our metamaterial designs\ncombine low losses with the extremely small group velocity associated with the\nresonant response in the transmission window, rendering them suitable for slow\nlight applications at room temperature."
    },
    {
        "anchor": "Structural relaxation and low energy properties of Twisted Bilayer\n  Graphene: The structural and electronic properties of twisted bilayer graphene are\ninvestigated from first principles and tight binding approach as a function of\nthe twist angle (ranging from the first \"magic\" angle $\\theta=1.08^\\circ$ to\n$\\theta=3.89^\\circ$, with the former corresponding to the largest unit cell,\ncomprising 11164 carbon atoms). By properly taking into account the long-range\nvan der Waals interaction, we provide the patterns for the atomic displacements\n(with respect to the ideal twisted bilayer). The out-of-plane relaxation shows\nan oscillating (\"buckling\") behavior, very evident for the smallest angles,\nwith the atoms around the AA stacking regions interested by the largest\ndisplacements. The out-of-plane displacements are accompanied by a significant\nin-plane relaxation, showing a vortex-like pattern, where the vorticity\n(intended as curl of the displacement field) is reverted when moving from the\ntop to the bottom plane and viceversa. Overall, the atomic relaxation results\nin the shrinking of the AA stacking regions in favor of the more energetically\nfavorable AB/BA stacking domains.\n  The measured flat bands emerging at the first magic angle can be accurately\ndescribed only if the atomic relaxations are taken into account. Quite\nimportantly, the experimental gaps separating the flat band manifold from the\nhigher and lower energy bands cannot be reproduced if only in-plane or only\nout-of-plane relaxations are considered. The stability of the relaxed bilayer\nat the first magic angle is estimated to be of the order of 0.5-0.9 meV per\natom (or 7-10 K). Our calculations shed light on the importance of an accurate\ndescription of the vdW interaction and of the resulting atomic relaxation to\nenvisage the electronic structure of this really peculiar kind of vdW bilayers.",
        "positive": "Gold in graphene: in-plane adsorption and diffusion: We study the bonding and diffusion of Au in graphene vacancies using\ndensity-functional theory. Energetics show that Au adsorbs preferably to double\nvacancies, steadily in-plane with graphene. All diffusion barriers for the\ncomplex of Au in double vacancy are above 4 eV, whereas the barriers for larger\nvacancies are below 2 eV. Our results support the main results of a recent\nexperiment [Gan et al., Small 4, 587 (2008)], but suggest that the observed\ndiffusion mechanism is not thermally activated, but radiation-enhanced."
    },
    {
        "anchor": "Detection of stacking faults breaking the [110]/[1-10] symmetry in\n  ferromagnetic semiconductors (Ga,Mn)As and (Ga,Mn)(As,P): We report high resolution x-ray diffraction measurements of (Ga,Mn)As and\n(Ga,Mn)(As,P) epilayers. We observe a structural anisotropy in the form of\nstacking faults which are present in the (111) and (11-1) planes and absent in\nthe (-111) and (1-11) planes. The stacking faults produce no macroscopic\nstrain. They occupy 0.01 - 0.1 per cent of the epilayer volume. Full-potential\ndensity functional calculations evidence an attraction of Mn_Ga impurities to\nthe stacking faults. We argue that the enhanced Mn density along the common\n[1-10] direction of the stacking fault planes produces sufficiently strong\n[110]/[1-10] symmetry breaking mechanism to account for the in-plane uniaxial\nmagnetocrystalline anisotropy of these ferromagnetic semiconductors.",
        "positive": "The d-p band-inversion topological insulator in bismuth-based\n  skutterudites: Skutterudites, a class of materials with cage-like crystal structure which\nhave received considerable research interest in recent years, are the breeding\nground of several unusual phenomena such as heavy fermion superconductivity,\nexciton-mediated superconducting state and Weyl fermions. Here, we predict a\nnew topological insulator in bismuth-based skutterudites, in which the bands\ninvolved in the topological band-inversion process are d- and p-orbitals, which\nis distinctive with usual topological insulators, for instance in Bi2Se3 and\nBiTeI the bands involved in the topological band-inversion process are only\np-orbitals. Due to the present of large d-electronic states, the electronic\ninteraction in this topological insulator is much stronger than that in other\nconventional topological insulators. The stability of the new material is\nverified by binding energy calculation, phonon modes analysis, and the finite\ntemperature molecular dynamics simulations. This new material can provide\nnearly zero-resistivity signal current for devices and is expected to be\napplied in spintronics devices."
    },
    {
        "anchor": "Systematic first-principles study of impurity hybridization in NiAl: We have performed a systematic first-principles computational study of the\neffects of impurity atoms (boron, carbon, nitrogen, oxygen, silicon, phosporus,\nand sulfur) on the orbital hybridization and bonding properties in the\nintermetallic alloy NiAl using a full-potential linear muffin-tin orbital\nmethod. The matrix elements in momentum space were used to calculate real-space\nproperties: onsite parameters, partial densities of states, and local charges.\nIn impurity atoms that are empirically known to be embrittler (N and O) we\nfound that the 2s orbital is bound to the impurity and therefore does not\nparticipate in the covalent bonding. In contrast, the corresponding 2s orbital\nis found to be delocalized in the cohesion enhancers (B and C). Each of these\nimpurity atoms is found to acquire a net negative local charge in NiAl\nirrespective of whether they sit in the Ni or Al site. The embrittler therefore\nreduces the total number of electrons available for covalent bonding by\nremoving some of the electrons from the neighboring Ni or Al atoms and\nlocalizing them at the impurity site. We show that these correlations also hold\nfor silicon, phosporus, and sulfur.",
        "positive": "Deep learning and the Schr\u00f6dinger equation: We have trained a deep (convolutional) neural network to predict the\nground-state energy of an electron in four classes of confining two-dimensional\nelectrostatic potentials. On randomly generated potentials, for which there is\nno analytic form for either the potential or the ground-state energy, the\nneural network model was able to predict the ground-state energy to within\nchemical accuracy, with a median absolute error of 1.49 mHa. We also\ninvestigate the performance of the model in predicting other quantities such as\nthe kinetic energy and the first excited-state energy of random potentials."
    },
    {
        "anchor": "NdAlSi: a magnetic Weyl semimetal candidate with rich magnetic phases\n  and atypical transport properties: Magnetic Weyl semimetals (MWSM) have attracted significant attention due to\ntheir intriguing physical properties and potential applications in\nspin-electronic devices. Here we report the characterization of NdAlSi\nincluding transport, magnetization, and heat capacity on single crystals, as\nwell as band structure calculation. It is a newly proposed MWSM candidate which\nbreaks both time-reversal and spacial inversion symmetries. A\ntemperature-magnetic field phase diagram is experimentally established.\nRemarkably, on the angular magnetoresistance (AMR), a two-fold symmetric sharp\npeak instead of a smooth variation is observed in the field-induced\nferrimagnetic phase. We argue that the tunability of both the topological and\nmagnetic properties in NdAlSi is crucial for realizing such a behavior. Our\nresults indicate that 4f-electron-based MWSM can provide a unique platform to\nexplore new and intriguing quantum phenomena arising from the interaction\nbetween magnetism and topology.",
        "positive": "The incommensurate magnet iron monophosphide FeP: Crystal growth and\n  characterization: We report an optimized chemical vapor transport method, which allows growing\nFeP single crystals up to 500 mg in mass and 80 $mm^{3}$ in volume. The high\nquality of the crystals obtained by this method was confirmed by means of EDX,\nhigh-resolution TEM, low-temperature single crystal XRD and neutron diffraction\nexperiments. We investigated the transport and magnetic properties of the\nsingle crystals and calculated the electronic band structure of FeP. We show\nboth theoretically and experimentally, that the ground state of FeP is\nmetallic. The examination of the magnetic data reveals antiferromagnetic order\nbelow T$_{N}$ =119 K while transport remains metallic in both the paramagnetic\nand the antiferromagnetic phase. The analysis of the neutron diffraction data\nshows an incommensurate magnetic structure with the propagation vector Q=(0, 0,\n$\\pm{\\delta}$), where ${\\delta}$ $\\sim$ 0.2. For the full understanding of the\nmagnetic state, further experiments are needed. The successful growth of large\nhigh-quality single crystals opens the opportunity for further investigations\nof itinerant magnets with incommensurate spin structures using a wide range of\nexperimental tools."
    },
    {
        "anchor": "Optical matrix elements in tight-binding models with overlap: We investigate the effect of orbital overlap on optical matrix elements in\nempirical tight-binding models. Empirical tight-binding models assume an\northogonal basis of (atomiclike) states and a diagonal coordinate operator\nwhich neglects the intra-atomic part. It is shown that, starting with an atomic\nbasis which is not orthogonal, the orthogonalization process induces\nintra-atomic matrix elements of the coordinate operator and extends the range\nof the effective Hamiltonian. We analyze simple tight-binding models and show\nthat non-orthogonality plays an important role in optical matrix elements. In\naddition, the procedure gives formal justification to the nearest-neighbor\nspin-orbit interaction introduced by Boykin [Phys. Rev \\textbf{B} 57, 1620\n(1998)] in order to describe the Dresselahaus term which is neglected in\nempirical tight-binding models.",
        "positive": "Tuning oxygen vacancy diffusion through strain in SrTiO$_3$ thin films: Understanding the diffusion of oxygen vacancies in oxides under different\nexternal stimuli is crucial for the design of ion-based electronic devices,\nimprove catalytic performance, etc. In this manuscript, using an external\nelectric field produced by an AFM tip, we obtain the room-temperature diffusion\ncoefficient of oxygen-vacancies in thin-films of SrTiO$_3$ under\ncompressive/tensile epitaxial strain. Tensile strain produces a substantial\nincrease of the diffusion coefficient, facilitating the mobility of vacancies\nthrough the film. Additionally, the effect of tip bias, pulse time, and\ntemperature on the local concentration of vacancies is investigated. These are\nimportant parameters of control in the production and stabilization of\nnon-volatile states in ion-based memresistive devices. Our findings show the\nkey role played by strain for the control of oxygen vacancy migration in\nthin-film oxides."
    },
    {
        "anchor": "Interfacial Piezoelectric Polarization Locking in Printable\n  Ti$_{3}$C$_{2}$T$_{\\mathit{x}}$ MXene-Fluoropolymer Composites: Piezoelectric fluoropolymers convert mechanical energy to electricity and are\nideal for sustainably providing power to electronic devices. To convert\nmechanical energy, a net polarization must be induced in the fluoropolymer,\nwhich is currently achieved via an energy intensive electrical poling process.\nEliminating this process will enable the low-energy production of efficient\nenergy harvesters. Here, by combining molecular dynamics simulations,\npiezoresponse force microscopy, and electrodynamic measurements, we reveal a\nhitherto unseen polarization locking phenomena of poly(vinylidene\nfluoride-$\\mathit{co}$-trifluoroethylene) (PVDF-TrFE) perpendicular to the\nbasal plane of two-dimensional (2D) Ti$_{3}$C$_{2}$T$_{\\mathit{x}}$ MXene\nnanosheets. This polarization locking, driven by strong electrostatic\ninteractions enabled exceptional energy harvesting performance, with a measured\npiezoelectric charge coefficient, $\\mathit{d_{33}}$, of -52.0 picocoulombs per\nnewton, significantly higher than electrically poled PVDF-TrFE (approximately\n-38 picocoulombs per newton). This study provides a new fundamental and low\nenergy input mechanism of poling fluoropolymers, which enables new levels of\nperformance in electromechanical technologies.",
        "positive": "Threshold fields for antiparallel ferroelectric domain wall motion: While an ideal antiparallel ferroelectric wall is considered a unit cell in\nwidth (~0.5nm), we show using phase field modeling that the threshold field for\nmoving this wall dramatically drops by 2-3 orders of magnitude if the wall were\ndiffuse by only ~2-3nm. Since antiparallel domain walls are symmetry allowed in\nall ferroelectrics, and since domain wall broadening on nanometer scale is\nwidely reported in literature, this mechanism is generally applicable to all\nferroelectrics."
    },
    {
        "anchor": "Finite-Size and surface effects in maghemite nanoparticles: Monte Carlo\n  simulations: Finite-size and surface effects in fine particle systems are investigated by\nMonte Carlo simulation of a model of a $\\gamma$-Fe$_2$O$_3$ (maghemite) single\nparticle. Periodic boundary conditions have been used to simulate the bulk\nproperties and the results compared with those for a spherical shaped particle\nwith free boundaries to evidence the role played by the surface on the\nanomalous magnetic properties displayed by these systems at low temperatures.\nSeveral outcomes of the model are in qualitative agreement with the\nexperimental findings. A reduction of the magnetic ordering temperature,\nspontaneous magnetization, and coercive field is observed as the particle size\nis decreased. Moreover, the hysteresis loops become elongated with high values\nof the differential susceptibility, resembling those from frustrated or\ndisordered systems. These facts are consequence of the formation of a surface\nlayer with higher degree of magnetic disorder than the core, which, for small\nsizes, dominates the magnetization processes of the particle. However, in\ncontradiction with the assumptions of some authors, our model does not predict\nthe freezing of the surface layer into a spin-glass-like state. The results\nindicate that magnetic disorder at the surface simply facilitates the thermal\ndemagnetization of the particle at zero field, while the magnetization is\nincreased at moderate fields, since surface disorder diminishes ferrimagnetic\ncorrelations within the particle. The change in shape of the hysteresis loops\nwith the particle size demonstrates that the reversal mode is strongly\ninfluenced by the reduced atomic coordination and disorder at the surface.",
        "positive": "Resonance Raman scattering and ab initio calculation of electron energy\n  loss spectra of MoS2 nanosheets: The presence of electron energy loss (EELS) peak is proposed theoretically in\nmolybdenum disulfide (MoS2) nanosheets. Using density functional theory\nsimulations and calculations, one EELS peak is identified in the visible energy\nrange, for MoS2 nanosheets with molybdenum vacancy. Experimentally, four\ndifferent laser sources are used for the Raman scattering study of MoS2\nnanosheets, which show two distinct Raman peaks, one at 385 cm-1 (E12g) and the\nother at 408 cm-1 (A1g). In the cases of three laser sources with wavelengths\n405 nm (3.06 eV), 632 nm (1.96 eV) and 785 nm (1.58 eV), respectively, the\nintensity of E12g Raman peak is more than the A1g Raman peak, while in the case\nof excitation source of 532 nm (2.33 eV), the intensity profile is reversed and\nA1g peak is the most intense. Thus a resonance Raman scattering phenomenon is\nobserved for 532 nm laser source."
    },
    {
        "anchor": "Response of graphene to femtosecond high-intensity laser irradiation: We study the response of graphene to high-intensity 10^11-10^12 Wcm^-2,\n50-femtosecond laser pulse excitation. We establish that graphene has a fairly\nhigh (~3\\times10^12Wcm^-2) single-shot damage threshold. Above this threshold,\na single laser pulse cleanly ablates graphene, leaving microscopically defined\nedges. Below this threshold, we observe laser-induced defect formation that\nleads to degradation of the lattice over multiple exposures. We identify the\nlattice modification processes through in-situ Raman microscopy. The effective\nlifetime of CVD graphene under femtosecond near-IR irradiation and its\ndependence on laser intensity is determined. These results also define the\nlimits of non-linear applications of graphene in femtosecond high-intensity\nregime.",
        "positive": "Molecular Beam Epitaxy Growth of Superconducting LiFeAs Film on\n  SrTiO3(001) Substrate: The stoichiometric \"111\" iron-based superconductor, LiFeAs, has attacted\ngreat research interest in recent years. For the first time, we have\nsuccessfully grown LiFeAs thin film by molecular beam epitaxy (MBE) on\nSrTiO3(001) substrate, and studied the interfacial growth behavior by\nreflection high energy electron diffraction (RHEED) and low-temperature\nscanning tunneling microscope (LT-STM). The effects of substrate temperature\nand Li/Fe flux ratio were investigated. Uniform LiFeAs film as thin as 3\nquintuple-layer (QL) is formed. Superconducting gap appears in LiFeAs films\nthicker than 4 QL at 4.7 K. When the film is thicker than 13 QL, the\nsuperconducting gap determined by the distance between coherence peaks is about\n7 meV, close to the value of bulk material. The ex situ transport measurement\nof thick LiFeAs film shows a sharp superconducting transition around 16 K. The\nupper critical field, Hc2(0)=13.0 T, is estimated from the temperature\ndependent magnetoresistance. The precise thickness and quality control of\nLiFeAs film paves the road of growing similar ultrathin iron arsenide films."
    },
    {
        "anchor": "Ultra-High Mechanical Flexibility of 2D Silicon Telluride: Silicon telluride (Si2Te3) is a two-dimensional material with a unique\nvariable structure where the silicon atoms form Si-Si dimers to fill the\n\"metal\" sites between the Te layers. The Si-Si dimers have four possible\norientations: three in-plane and one out-of-the plane directions. The\nstructural variability of Si2Te3 allows unusual properties especially the\nmechanical properties. Using results from first-principles calculations, we\nshow that the Si2Te3 monolayer can sustain a uniaxial tensile strain up to 38%,\nhighest among all two-dimensional materials reported. The high mechanical\nflexibility allows applying mechanical strain to reduce the band gap by 1.4 eV.\nWith increasing strain, the band gap undergoes an unusual\nindirect-direct-indirect-direct transition. We also show that the uniaxial\nstrain can effectively control the Si-Si dimer alignment, which is beneficial\nfor practical applications.",
        "positive": "A Bayesian Committee Machine Potential for Organic Nitrogen Compounds: Large-scale computer simulations of chemical atoms are used in a wide range\nof applications, including batteries, drugs, and more. However, there is a\nproblem with efficiency as it takes a long time due to the large amount of\ncalculation. To solve these problems, machine learning interatomic potential\n(ML-IAP) technology is attracting attention as an alternative. ML-IAP not only\nhas high accuracy by faithfully expressing the density functional theory (DFT),\nbut also has the advantage of low computational cost. However, there is a\nproblem that the potential energy changes significantly depending on the\nenvironment of each atom, and expansion to a wide range of compounds within a\nsingle model is still difficult to build in the case of a kernel-based model.\nTo solve this problem, we would like to develop a universal ML-IAP using this\nactive Bayesian Committee Machine (BCM) potential methodology for\ncarbon-nitrogen-hydrogen (CNH) with various compositions. ML models are trained\nand generated through first-principles calculations and molecular dynamics\nsimulations for molecules with only CNH. Using long amine structures to test an\nML model trained only with short chains, the results show excellent consistency\nwith DFT calculations. Consequently, machine learning-based models for organic\nmolecules not only demonstrate the ability to accurately describe various\nphysical properties but also hold promise for investigating a broad spectrum of\ndiverse materials systems."
    },
    {
        "anchor": "Natural Spider Silk Nanofibrils Produced by Assembling Molecules or\n  Disassembling Fibers: Spider silk is biocompatible, biodegradable, and rivals some of the best\nsynthetic materials in terms of strength and toughness. Despite extensive\nresearch, comprehensive experimental evidence of the formation and morphology\nof its internal structure is still limited and controversially discussed. Here,\nwe report the complete mechanical decomposition of natural silk fibers from the\ngolden silk orb-weaver Trichonephila clavipes into ~10 nm-diameter nanofibrils,\nthe material's apparent fundamental building blocks. Furthermore, we produced\nnanofibrils of virtually identical morphology by triggering an intrinsic\nself-assembly mechanism of the silk proteins. Independent physico-chemical\nfibrillation triggers were revealed, enabling fiber assembly from stored\nprecursors \"at-will\". This knowledge furthers the understanding of this\nexceptional material's fundamentals, and ultimately, leads toward the\nrealization of silk-based high-performance materials.",
        "positive": "Tailoring the diameter of decorated CN nanotubes by temperature\n  variations using HF-CVD: Patterned films of decorated nitrogenated carbon (C-N) nanotubes were\ncatalytically synthesised by hot filament chemical vapour deposition (HF-CVD)\nin a nitrogen-methane-ammonia environment. The systematic study of a transition\nbetween different kinds of C-N nanostructures as a function of the local\nsubstrate temperature ranging from 700 up to 820C is presented. The morphology,\nthe diameter as well as the properties of the generated tubular structures\nshowed strong dependence on this parameter. By means of electron microscopy a\nnew type of decoration covering all tubular structures was observed. Buckled\nlattice fringes revealed the disordered graphitic-like character of the hollow\nC-N nanotubes. Raman spectroscopy confirmed a transition in the microscopic\norder as a function of temperature. Furthermore field emission in vacuum was\nstudied and showed a spectacular correlation to the deposition temperature and\ntherefore the diameter of the C-N tubes. For arrays of tubes thinner than 50 nm\nan onset field below 4 V/um was observed."
    },
    {
        "anchor": "Double-loop hysteresis of multisite dilute Sr(Y$_{1-x}$Dy$_x$)$_2$O$_4$\n  single crystal Kramers paramagnets: electron-phonon interaction, quantum\n  tunneling and cross-relaxation: Experimental and theoretical studies of the dynamic magnetization in swept\nmagnetic fields of the orthorhombic SrY$_2$O$_4$ single-crystals doped with the\nDy$^{3+}$ Kramers ions (0.01 and 0.5 at.%) with natural abundances of even and\nodd Dy isotopes are presented. Impurity ions substitute for Y$^{3+}$ ions at\ntwo nonequivalent crystallographic sites with the same local $C_s$ symmetry but\nstrongly different crystal fields. Well pronounced double-loop hysteresis is\nobserved at temperatures 2, 4, 5 and 6 K for sweeping rates of 5 and 1 mT/s.\nThe microscopic model of spectral, magnetic and kinetic properties of Dy$^{3+}$\nions is developed based on the results of EPR, site selective optical spectra\nand magnetic relaxation measurements. The derived approach to the dynamic\nmagnetization in the sweeping field based on the numerical solution of\ngeneralized master equations with time-dependent transition probabilities\ninduced by the electron-phonon interaction, quantum tunneling and\ncross-relaxation allowed us to reproduce successfully the evolution of the\nhysteresis loop shape with temperature, sweeping rate and concentration of\nparamagnetic ions.",
        "positive": "Evaluation of GlassNet for physics-informed machine learning of glass\n  stability and glass-forming ability: Glasses form the basis of many modern applications and also hold great\npotential for future medical and environmental applications. However, their\nstructural complexity and large composition space make design and optimization\nchallenging for certain applications. Of particular importance for glass\nprocessing is an estimate of a given composition's glass-forming ability (GFA).\nHowever, there remain many open questions regarding the physical mechanisms of\nglass formation, especially in oxide glasses. It is apparent that a proxy for\nGFA would be highly useful in glass processing and design, but identifying such\na surrogate property has proven itself to be difficult. Here, we explore the\napplication of an open-source pre-trained NN model, GlassNet, that can predict\nthe characteristic temperatures necessary to compute glass stability (GS) and\nassess the feasibility of using these physics-informed ML (PIML)-predicted GS\nparameters to estimate GFA. In doing so, we track the uncertainties at each\nstep of the computation - from the original ML prediction errors, to the\ncompounding of errors during GS estimation, and finally to the final estimation\nof GFA. While GlassNet exhibits reasonable accuracy on all individual\nproperties, we observe a large compounding of error in the combination of these\nindividual predictions for the prediction of GS, finding that random forest\nmodels offer similar accuracy to GlassNet. We also breakdown the ML performance\non different glass families and find that the error in GS prediction is\ncorrelated with the error in crystallization peak temperature prediction.\nLastly, we utilize this finding to assess the relationship between\ntop-performing GS parameters and GFA for two ternary glass systems: sodium\nborosilicate and sodium iron phosphate glasses. We conclude that to obtain true\nML predictive capability of GFA, significantly more data needs to be collected."
    },
    {
        "anchor": "Cu-substituted Fe2P: An emerging candidates for magnetic RAM application: We propose that Cu-substituted Fe$_2$P, (Fe$_{1-x}$Cu$_x$)$_2$P ($x\\sim\n0.16$), to be an outstanding contender for the STT-MRAM application. Using\nfirst principles based calculations in the framework of density functional\ntheory and through Monte Carlo simulations, we demonstrate that this material\ncan be used as ferromagnetic electrode in the magnetic tunnel junction (MTJ) of\nSTT-MRAM due to its moderate perpendicular magnetic anisotropy (PMA), large\ntunnel magneto-resistance (TMR), good thermal stability and high ferromagnetic\ntransition temperature. We point out that the simplicity in the synthesis, huge\nabundance, and non-toxicity make this material a very good candidate to replace\nthe current MTJ materials for STT-MRAM such as FePt,~FeCo or FeCoB.",
        "positive": "Charge Carrier Dynamics of Methylammonium Lead-Iodide Perovskite Solar\n  Cells: Transient opto-electrical measurements of methylammonium lead iodide (MALI)\nperovskite solar cells (PSCs) are performed and analyzed in order to elucidate\nthe operating mechanisms. The current response to a light pulse or voltage\npulse shows an extraordinarily broad dynamic range covering 9 orders of\nmagnitude in time - from microseconds to minutes - until steady-state is\nreached. Evidence of a slowly changing charge density at the perovskite layer\nboundaries is found, which is most probably caused by mobile ions.\nCurrent-voltage curves (IV curves) are measured with very fast scan-rate after\nkeeping the cell for several seconds at a constant voltage as proposed by Tress\net al. Numerical drift-diffusion simulations reproduce the measured IV curves\nusing different distributions of ions in the model. Analysing the band diagram\nof the simulation result sheds light on the operating mechanism. To further\ninvestigate the effects at short time scales (below milliseconds)\nphoto-generated charge extraction by linearly increasing voltage (photo-CELIV)\nexperiments are performed. We postulate that mobility imbalance in combination\nwith deep hole trapping leads to dynamic doping causing effects from\nmicroseconds to milliseconds. Comprehensive transient drift-diffusion\nsimulations of the photo-CELIV experiments strengthen this hypothesis. This\nadvanced characterization approach combining dynamic response measurements and\nnumerical simulations represents a key step on the way to a comprehensive\nunderstanding of device working mechanisms in emerging perovskite solar cells."
    },
    {
        "anchor": "Steering in-plane shear waves with inertial resonators in platonic\n  crystals: Numerical simulations shed light on control of shear elastic wave propagation\nin plates structured with inertial resonators. The structural element is\ncomposed of a heavy core connected to the main freestanding plate through tiny\nligaments. It is shown that such a configuration exhibits a complete band gap\nin the low frequency regime. As a byproduct, we further describe the asymmetric\ntwisting vibration of a single scatterer via modal analysis, dispersion and\ntransmission loss. This might pave the way to new functionalities such as\nfocusing and self-collimation in elastic plates.",
        "positive": "Curie Temperature Trends in (III,Mn)V Ferromagnetic Semiconductors: We present a theoretical survey of ferromagnetic transition temperatures in\ncubic (III,Mn)V semiconductors based on a model with $S=5/2$ local moments\nexchange-coupled to itinerant holes in the host semiconductor valence band.\nStarting from the simplest mean-field theory of this model, we estimate the\n$T_c$ enhancement due to exchange and correlation in the itinerant-hole system,\nand the $T_c$ suppression due to collective fluctuations of the ordered\nmoments. We show that high critical temperatures in these ferromagnetic\nsemiconductors require both the large magnetic susceptibility contribution from\nthe valence band's heavy holes and the large spin stiffness that results from\nstrong spin-orbit coupling in the valence band. Our calculations demonstrate\nthat this model for the ferromagnetism of these systems is fully consistent\nwith the room-temperature ferromagnetism reported for Mn doped nitrides."
    },
    {
        "anchor": "Effect of Ge-substitution on Magnetic Properties in the Itinerant Chiral\n  Magnet MnSi: We have investigated the effect of Ge-substitution to the magnetic ordering\nin the B20 itinerant chiral magnet MnSi prepared by melting and annealing under\nambient pressure. From metallurgical survey, the solubility limit of Ge was\nfound to be $x=0.144(5)$ with annealing temperature $T_\\mathrm{an} = 1073$ K.\nMagnetization measurements on MnSi$_{1-x}$Ge$_x$ samples show that the helical\nordering temperature $T_{\\mathrm{c}}$ increases rapidly in the low-$x$ range,\nwhereas it becomes saturated at higher concentration $x>~0.1$. The Ge\nsubstitution also increases both the saturation magnetization $M_\\mathrm{s}$\nand the critical field to the fully polarized state $H_\\mathrm{c2}$. In\ncontrast to the saturation behavior of $T_\\mathrm{c}$, those parameters\nincrease linearly up to the highest Ge concentration investigated. In the\ntemperature-magnetic field phase diagram, we found enlargement of the skyrmion\nphase region for large $x$ samples. We, furthermore, observed the non-linear\nbehavior of helical modulation vector $k$ as a function of Ge concentration,\nwhich can be described qualitatively using the mean field approximation.",
        "positive": "\\textit{Ab initio} molecular dynamics study of the structural and\n  electronic transition in VO$_2$: The temperature-induced structural and electronic transformation in VO$_2$\nbetween the monoclinic M1 and tetragonal rutile phases was studied by means of\n\\textit{ab initio} molecular dynamics, based on density functional theory with\nHubbard correction (DFT+U). Analysis of the dynamical processes associated with\nthe structural transformation was carried out on the atomic scale by following\nthe time evolution of dimerization amplitudes of vanadium atom chains and the\ntwisting angle of vanadium dimers. The electronic transition was studied by\ntracing the changes in projected densities of states and their correlation with\nthe evolution of the structural transformation. Our results reveal a strong\ninterconnection between the structural and electronic transformations and show\nthat they take place on the same time scale."
    },
    {
        "anchor": "Effect of intrinsic instability of cantilevers on static mode Atomic\n  Force Spectroscopy: We show that the static force spectroscopy curve is significantly modified\ndue to presence of intrinsic cantilever instability. This instability acts in\ntandem with such instabilities like water bridge or molecular bond rupture and\nmakes the static force spectroscopy curve (including \"jump-off-contact\")\ndependent on the step-size of the movement of sample stage. A model has been\nproposed to explain the data. This has been further validated by applying an\nelectric field between tip and substrate which modifies the tip-substrate\ninteraction.",
        "positive": "Challenges and Opportunities in Implementing Negative Differential\n  Resistance Mode Reconfigurable Field Effect Transistors: Desirably, the world relies on the devices being compact, as they could drive\nto the increased functionality of integrated circuits at the provided footstep,\nthat is becoming more reliable. To reduce the scalability over the devices,\napproach has been outlined utilizing the NDR mode reconfigurable functionality\nover the transistors. Being an individual device efficient in exhibiting\ndifferent task with the different configurations in the same physical\ncircuitry. On the view of reconfigurable transistors, possibly authorize the\nreconfiguration from a p-type to n-type channel transistor has been expelled as\nan emerging application such as static memory cells, fast switching logic\ncircuits as well as energy efficient computational multi valued logic. This\narticle emphasizes NDR mode RFET along with its classification, followed by\nenhancing the RFET technology concepts and RFETs future potential has been\ndiscussed briefing with the growing applications like hardware security as well\nas neuro-inspired computing."
    },
    {
        "anchor": "$\\texttt{Spglib}$: a software library for crystal symmetry search: A computer algorithm to search symmetries of crystal structures as\nimplemented in the \\texttt{spglib} code is described. An iterative algorithm is\nemployed to robustly identify space group types tolerating a certain amount of\ndistortion in the crystal structures. The source code is distributed under the\n3-Clause BSD License, a permissive open-source software license. This paper\nfocuses on the algorithm for identifying the space group symmetry of the\ncrystal structures.",
        "positive": "How Thermal Annealing Process Determines the Inherent Structure\n  Evolution in Amorphous Silicon: An Investigation from Atomistic Time Scales\n  to Experimental Time Scales: The annealing treatment in the advanced manufacturing process, e.g.,\nlaser-assisted manufacturing, determines the final state of glasses which is\ncritical to its thermal, electrical and mechanical properties. Energy barriers\nanalysis based on the potential energy surface offers an effective way to study\nthe microscopic evolution of the inherent structures during the annealing\nprocess in a broadening timescale range, i.e., from atomistic timescale ( ~ ps)\nto experimental timescale (~ s). Here, we find the distribution activation\nenergy barriers in the potential energy surface can be divided into three\nregimes 1, the distribution mainly follows the Rayleigh distribution when the\nannealing rate Rdot < 1e15 K/s; 2, two different modes, i.e., an exponentially\ndecaying mode and a Rayleigh distribution mode, are found in the spectra when\nthe annealing rate 1e15 K/s < Rdot < instant; 3, the spectra is almost\nfollowing the exponentially decaying mode when the system is under the instant\nannealing process. However, the spectra of relaxation energy barriers only show\nan exponentially decaying mode with a decreasing decay parameter. A multi\ntimescale model for any specific annealing rate, which is beyond the limit of\nthe conventional atomistic simulations, i.e., molecular dynamics simulations,\nis then proposed based on the distribution of the energy barriers. Such a model\nenables quantitative explanations and predictions of the heat release during\nthe annealing process of the nanocalorimetry measurements or laser-assisted\nmanufacturing."
    },
    {
        "anchor": "Computational characterization and prediction of metal-organic framework\n  properties: In this introductory review, we give an overview of the computational\nchemistry methods commonly used in the field of metal-organic frameworks\n(MOFs), to describe or predict the structures themselves and characterize their\nvarious properties, either at the quantum chemical level or through classical\nmolecular simulation. We discuss the methods for the prediction of crystal\nstructures, geometrical properties and large-scale screening of hypothetical\nMOFs, as well as their thermal and mechanical properties. A separate section\ndeals with the simulation of adsorption of fluids and fluid mixtures in MOFs.",
        "positive": "Polarization-tuneable excitonic spectral features in the optoelectronic\n  response of atomically thin ReS2: The low crystal symmetry of rhenium disulphide (ReS2) leads to the emergence\nof dichroic optical and optoelectronic response, absent in other layered\ntransition metal dichalcogenides, which could be exploited for device\napplications requiring polarization resolution. To date, spectroscopy studies\non the optical response of ReS2 have relied almost exclusively in\ncharacterization techniques involving optical detection, such as\nphotoluminescence, absorbance, or reflectance spectroscopy. However, to realize\nthe full potential of this material, it is necessary to develop knowledge on\nits optoelectronic response with spectral resolution. In this work, we study\nthe polarization-dependent photocurrent spectra of few-layer ReS2\nphotodetectors, both in room conditions and at cryogenic temperature. Our\nspectral measurements reveal two main exciton lines at energies matching those\nreported for optical spectroscopy measurements, as well as their excited\nstates. Moreover, we also observe an additional exciton-like spectral feature\nwith a photoresponse intensity comparable to the two main exciton lines. We\nattribute this feature, not observed in earlier photoluminescence measurements,\nto a non-radiative exciton transition. The intensities of the three main\nexciton features, as well as their excited states, modulate with linear\npolarization of light, each one acquiring maximal strength at a different\npolarization angle. We have performed first-principles exciton calculations\nemploying the Bethe-Salpeter formalism, which corroborate our experimental\nfindings. Our results bring new perspectives for the development of ReS2-based\nnanodevices."
    },
    {
        "anchor": "Influence of excited electron lifetimes on the electronic structure of\n  carbon nanotubes: We have studied the dynamics of electrons in single wall carbon nanotubes\nusing femtosecond time-resolved photoemission. The lifetime of electrons\nexcited to the pi* bands is found to decrease continuously from 130 fs at 0.2\neV down to less than 20 fs at energies above 1.5 eV with respect to the Fermi\nlevel. This should lead to a significant lifetime--induced broadening of the\ncharacteristic van Hove singularities in the nanotube DOS.",
        "positive": "Electronic structure of (organic-)inorganic metal halide perovskites:\n  the dilemma of choosing the right functional: Organic-inorganic metal halide perovskites (HaPs) are intensively studied for\ntheir light-harvesting properties. Owing to the interplay between strong\nelectron-electron interaction and spin-orbit coupling (SOC), their quantitative\ntheoretical description is still a challenge as evidenced by the wide variety\nof results available in literature. Here, various methodologies for computing\ntheir electronic structure are evaluated, also accounting for SOC. More\nspecific, the GW approach as well as variants of the hybrid functionals PBE0\nand HSE are at the center of our investigations. For both functionals, we\nexplore methods to determine the mixing parameter $\\alpha$, and for HSE, we\ninvestigate the impact of the screening-parameter $\\omega$. An extensive\ninvestigation of PbI2, a precursor of many HaPs, leads to the conclusion that\nhybrid functionals with $\\alpha$ tuned by the density-based mixing method are\nmost suitable for obtaining band gaps comparable to $G_0W_0$ results. Moreover,\nthis methodology is transferable to CsPbI3, and the same behaviour is expected\nfor the entire family of lead-iodine perovskites."
    },
    {
        "anchor": "Predicting nanocrystal morphology governed by interfacial strain: The shape dependence for the technologically important nickel oxide (NiO)\nnanocrystals on (001) strontium titanate substrates is investigated under the\ngeneralized Wulff-Kaichew (GWK) theorem framework. It is found that the shape\nof the NiO nanocrystals is primarily governed by the existence (or absence) of\ninterfacial strain. Nanocrystals that have a fully pseudomorphic interface with\nthe substrate (i.e. the epitaxial strain is not relaxed) form an embedded\nsmooth ball-crown morphology with {001}, {011}, {111} and high-index {113}\nexposed facets with a negative Wulff point. On the other hand, when the\ninterfacial strain is relaxed by misfit dislocations, the nanocrystals take on\na truncated pyramidal shape, bounded by {111} faces and a {001} flat top, with\na positive Wulff point. Our quantitative model is able to predict both\nexperimentally observed shapes and sizes with good accuracy. Given the\nincreasing demand for hetero-epitaxial nanocrystals in various physio-chemical\nand electro-chemical functional devices, these results lay the important\ngroundwork in exploiting the GWK theorem as a general analytical approach to\nexplain hetero-epitaxial nanocrystal growth on oxide substrates governed by\ninterface strain.",
        "positive": "Effect of co-existing crystal structures on magnetic properties of\n  Ni_2Mn_(1+x)Sn_(1-x) magnetic shape memory alloy: The temperature dependent crystal structure analysis in martensitic phase of\nNi_2Mn_(1+x)Sn_(1-x) (x = 0.40 and 0.44) magnetic shape memory alloy is\nperformed using X-ray diffraction. The martensitic phase consists of 4-Layered\nand 14-Layered orthorhombic structure. The phase fraction of 4-layered and\n14-layered orthorhombic structure change with temperature. Interestingly, the\nmagnetic property also changes with temperature and corresponds to structural\nchange temperature. Thus, the exchange coupling constant between original Mn\nand substituted Mn is calculated, which shows that the 4-layered and 14-layered\northorhombic structures have different strength of antiferromagnetic coupling.\nThe analysis explain the origin of spin glass behavior and unusual exchange\nbias effect in these systems under zero-field-cooling."
    },
    {
        "anchor": "Total transmission and total reflection by zero index materials: In this report, we achieved total transmission and reflection in a slab of\nzero index materials with defect(s). By controlling the defect's radius and\ndielectric constant, we can obtain total transmission and reflection of EM\nwave. The zero index materials, in this report, stand for materials with\npermittivity and permeability which are simultaneously equal to zero or so\ncalled matched impedance zero index materials. Along with theoretical\ncalculations and simulation demonstrations, we also discuss about some possible\napplications for the proposed structure such as shielding or cloaking an object\nwithout restricting its view. We also suggest a way to control total\ntransmission and reflection actively by using tunable refractive index\nmaterials such as liquid crystal and BST. The physics behind those phenomena is\nattributed to intrinsic properties of zero index materials: constant field\ninside zero index slab.",
        "positive": "Magnetic Hyperthermia with Fe3O4 nanoparticles: the Influence of\n  Particle Size on Energy Absorption: We have studied the magnetic and power absorption properties of a series of\nmagnetic nanoparticles (MNPs) of Fe3O4 with average sizes <d> ranging from 3 to\n26 nm. Heating experiments as a function of particle size revealed a strong\nincrease in the specific power absorption (SPA) values for particles with <d> =\n25-30 nm. On the other side saturation magnetization MS values of these MNPs\nremain essentially constant for particles with <d> above 10 nm, suggesting that\nthe absorption mechanism is not determined by MS. The largest SPA value\nobtained was 130 W/g, corresponding to a bimodal particle distribution with\naverage size values of 17 and 26 nm."
    },
    {
        "anchor": "Vibrational properties of graphene nanoribbons by first-principles\n  calculations: We investigated the vibrational properties of graphene nanoribbons by means\nof first-principles calculations on the basis of density functional theory. We\nconfirm that the phonon modes of graphene nanoribbons with armchair and zigzag\ntype edges can be interpreted as fundamental oscillations and their overtones.\nThese show a characteristic dependence on the nanoribbon width. Furthermore, we\ndemonstrate that a mapping of the calculated Gamma-point phonon frequencies of\nnanoribbons onto the phonon dispersion of graphene corresponds to an\n\"unfolding\" of nanoribbons' Brillouin zone onto that of graphene. We consider\nthe influence of spin states with respect to the phonon spectra of zigzag\nnanoribbons and provide comparisons of our results with past studies.",
        "positive": "Thermal Conductivity and Mechanical Properties of Nitrogenated Holey\n  Graphene: Nitrogenated holey graphene (NHG), a two-dimensional graphene-derived\nmaterial with a C2N stoichiometry and evenly distributed holes and nitrogen\natoms in its basal plane, has recently been synthesized. We performed first\nprinciples calculations and molecular dynamics simulations to investigate\nmechanical and heat transport properties of this novel two-dimensional material\nat various temperatures. First principles calculations based on density\nfunctional theory yield an elastic modulus of 400 +/- 5 GPa at 0 K, 10% larger\nthan predicted by molecular dynamics simulations at low temperatures. We\nobserved an overall decreasing trend in elastic modulus and tensile strength as\ntemperature increases. At room temperature, we found that NHG can present a\nremarkable elastic modulus of 335 +/- 5 GPa and tensile strength of 60 GPa. We\nalso investigated the thermal conductivity of NHG via non-equilibrium molecular\ndynamics simulations. At 300 K an intrinsic thermal conductivity of 64.8 W/m-K\nwas found, with an effective phonon mean free path of 34.0 nm, both of which\nare smaller than respective values for graphene, and decrease with temperature.\nOur modeling-based predictions should serve as guide to experiments concerning\nphysical properties of this novel material."
    },
    {
        "anchor": "Thermal properties of composite materials with a complex fractal\n  structure: In this work, we report the thermal characterization of platelike composite\nsamples made of polyester resin and magnetite inclusions. By means of\nphotoacoustic spectroscopy and thermal relaxation, the thermal diffusivity,\nconductivity and volumetric heat capacity of the samples were experimentally\nmeasured. The volume fraction of inclusions was systematically varied in order\nto study the changes in the effective thermal conductivity of the composites.\nIn some samples, a static magnetic field was applied during the polymerization\nprocess resulting in anisotropic inclusion distributions. Our results show a\ndecrease in the thermal conductivity of some of the anisotropic samples\ncompared to the isotropic randomly distributed ones. Our analysis indicates\nthat the development of elongated inclusion structures leads to the formation\nof magnetite and resin domains causing this effect. We correlate the complexity\nof the inclusion structure with the observed thermal response by a multifractal\nand lacunarity analysis. All the experimental data are contrasted with the well\nknown Maxwell-Garnett's effective media approximation for composite materials.",
        "positive": "Definitive spectroscopic determination of the transverse interactions\n  responsible for the magnetic quantum tunneling in Mn12-acetate: We present detailed angle-dependent single crystal electron paramagnetic\nresonance (EPR) data for field rotations in the hard plane of the S=10 single\nmolecule magnet Mn12-acetate. A clear four-fold variation in the resonance\npositions may be attributed to an intrinsic fourth order transverse anisotropy\n(O44). Meanwhile, a four-fold variation of the EPR lineshapes confirms a\nrecently proposed model wherein disorder associated with the acetic acid of\ncrystallization induces a locally varying quadratic (rhombic) transverse\nanisotropy (O22). These findings explain most aspects of the magnetic quantum\ntunneling observed in Mn12-acetate."
    },
    {
        "anchor": "Magnetic properties of cobalt doped ZrO$_2$ nanoparticles: Evidence of\n  Co segregation: We synthesized pure and Co-doped (6.25 12.5 at.) ZrO$_2$ nanopowders in order\nto study their magnetic properties.We analyzed magnetic behavior as a function\nof the amount of Co and the oxygenation, which was controlled by low pressure\nthermal treatments. As prepared pure and Co-doped samples are diamagnetic and\nparamagnetic respectively. Ferromagnetism can be induced by performing low\npressure thermal treatments, which becomes stronger as the dwell time of the\nthermal treatment is increased. This behavior can be reversed, recovering the\ninitial diamagnetic or paramagnetic behavior, by performing reoxidizing thermal\ntreatments. Also, a cumulative increase can be observed in the saturation of\nthe magnetization with the number of low pressure thermal treatments performed.\nWe believe that this phenomenon indicates that cobalt segregation induced by\nthe thermal treatments is the responsible for the magnetic properties of the\nZrO$_2$ Co system.",
        "positive": "Centers of near-IR luminescence in Bi-doped SiO2 and GeO2:\n  First-principle modeling and experimental data analysis: First-principle study of possible bismuth-related centers in SiO2 and GeO2\nhosts is performed and the results are compared with the experimental data. The\nfollowing centers are modeled: trivalent and divalent Bi substitutional\ncenters; BiO interstitial molecule; interstitial ion, Bi^+, and atom, Bi^0;\nBi...Si-Si and Bi...Ge-Ge complexes formed by interstitial Bi atoms and glass\nintrinsic defects, Si-Si or Ge-Ge oxygen vacancies; interstitial dimers, Bi0\nand Bi_2^-. Experimental data available on bismuth-related IR luminescence in\nSiO2:Bi and GeO2:Bi glasses, visible (red) luminescence in SiO2:Bi glass and\nthe luminescence excitation are analyzed. Comparison of the calculated spectral\nproperties of the bismuth-related centers with the experimental data shows that\nIR luminescence in SiO2:Bi and GeO2:Bi is most likely caused by Bi...Si-Si and\nBi...Ge-Ge complexes and divalent Bi substitutional center is probably\nresponsible for the red luminescence in SiO2:Bi."
    },
    {
        "anchor": "Dynamics of systems with isotropic competing interactions in an external\n  field: a Langevin approach: We study the Langevin dynamics of a ferromagnetic Ginzburg-Landau Hamiltonian\nwith a competing long-range repulsive term in the presence of an external\nmagnetic field. The model is analytically solved within the self consistent\nHartree approximation for two different initial conditions: disordered or zero\nfield cooled (ZFC), and fully magnetized or field cooled (FC). To test the\npredictions of the approximation we develop a suitable numerical scheme to\nensure the isotropic nature of the interactions. Both the analytical approach\nand the numerical simulations of two-dimensional finite systems confirm a\nsimple aging scenario at zero temperature and zero field. At zero temperature a\ncritical field $h_c$ is found below which the initial conditions are relevant\nfor the long time dynamics of the system. For $h < h_c$ a logarithmic growth of\nmodulated domains is found in the numerical simulations but this behavior is\nnot captured by the analytical approach which predicts a $t^1/2$ growth law at\n$T = 0$.",
        "positive": "Electron-Hole Asymmetry in Single-Walled Carbon Nanotubes Probed by\n  Direct Observation of Transverse Quasi-Dark Excitons: We studied the asymmetry between valence and conduction bands in\nsingle-walled carbon nanotubes (SWNTs) through the direct observation of\nspin-singlet transverse dark excitons using polarized photoluminescence\nexcitation spectroscopy. The intrinsic electron-hole (e-h) asymmetry lifts the\ndegeneracy of the transverse exciton wavefunctions at two equivalent K and K'\nvalleys in momentum space, which gives finite oscillator strength to transverse\ndark exciton states. Chirality-dependent spectral weight transfer to transverse\ndark states was clearly observed, indicating that the degree of the e-h\nasymmetry depends on the specific nanotube structure. Based on comparison\nbetween theoretical and experimental results, we evaluated the band asymmetry\nparameters in graphene and various carbon nanotube structures."
    },
    {
        "anchor": "Atomistic mechanisms of twin-twin interactions in Cu nanopillars: Twinning is an important mode of plastic deformation in metallic nanopillars.\nWhen twinning occurs on multiple systems, it is possible that twins belonging\nto different twin systems interact and forms a complex twin-twin junctions.\nRevealing the atomistic mechanisms of how twin-twin interactions lead to\ndifferent twin junctions is crucial for our understanding of mechanical\nbehaviour of materials. In this paper, we report the atomistic mechanisms\nresponsible for the formation of two different twin-twin interactions/junctions\nin Cu nanopillars using atomistic simulations. One junction contains two twin\nboundaries along with one $\\Sigma$9 boundary, while the other contains five\ntwin boundaries (five-fold twin). These junctions were observed during the\ntensile deformation of [100] and $[1\\bar1 0]$ Cu nanopillars, respectively.",
        "positive": "Multiple quantum dynamics in a system of dipole-coupling spins in solid: A perturbation method deals with dipolar coupling spins in solids is\npresented. As examples of the application the method, the multile-quantum\ncoherence dynamics in clusters of a linear chain of four nuclear spins and a\nring of six spins coupled by dipole-dipole interaction are considered. The\ncalculated 0Q- and 2Q intensities in a linear chain of four nuclear spins and\n6Q intensity in a ring of six spins vs the duration of the preparation period\nagree well with the exact solutions (for linear chain of four nuclear spins)\nand simulation data (for linear chain of four nuclear spins and a ring of six\nspin)."
    },
    {
        "anchor": "Epitaxial single-crystal growth of transition metal dichalcogenide\n  monolayers via atomic sawtooth Au surface: Growth of two-dimensional van der Waals layered single-crystal (SC) films is\nhighly desired to manifest intrinsic material sciences and unprecedented\ndevices for industrial applications. While wafer-scale SC hexagonal boron\nnitride film has been successfully grown, an ideal growth platform for diatomic\ntransition metal dichalcogenide (TMdC) film has not been established to date.\nHere, we report the SC growth of TMdC monolayers in a centimeter scale via\natomic sawtooth gold surface as a universal growth template. Atomic\ntooth-gullet surface is constructed by the one-step solidification of liquid\ngold, evidenced by transmission-electron-microscopy. Anisotropic adsorption\nenergy of TMdC cluster, confirmed by density-functional calculations, prevails\nat the periodic atomic-step edge to yield unidirectional epitaxial growth of\ntriangular TMdC grains, eventually forming the SC film, regardless of Miller\nindices. Growth using atomic sawtooth gold surface as a universal growth\ntemplate is demonstrated for several TMdC monolayer films, including WS2, WSe2,\nMoS2, MoSe2/WSe2 heterostructure, and W1-xMoxS2 alloy. Our strategy provides a\ngeneral avenue for the SC growth of diatomic van der Waals heterostructures in\na wafer scale, to further facilitate the applications of TMdCs in post silicon\ntechnology.",
        "positive": "Switchable and unswitchable bulk photovoltaic effect in two-dimensional\n  interlayer-sliding ferroelectrics: Spontaneous polarization and bulk photovoltaic effect (BPVE) are two\nconcomitant physical properties in ferroelectric materials. The flipping of\nferroelectric order usually accompanies with the switching of BPVE as both of\nthem are reversed under the inversion symmetry. In this study, we report the\ndistinctive BPVE characters in two-dimensional (2D) interlayer sliding\nferroelectric materials featuring unswitchable in-plane BPVE (light-induced\nphotocurrent in the xy plane) and switchable out-of-plane BPVE (light-induced\npolarization along the z-direction). Symmetry analysis within abstract bilayer\ncrystal model and first-principles calculations validate these BPVE properties.\nIt is because the positive and negative ferroelectric states caused by\ninterlayer sliding are related by mirror symmetry which cannot flip all the\nBPVE tensor elements. This finding extends the understanding of the\nrelationship between ferroelectricity and BPVE. On one hand, the switchable\nout-of-plane BPVE can be used to design switchable photoelectric devices. On\nthe other hand, the in-plane BPVE is robust against the ferroelectric flipping,\nand the unswitchable character is beneficial to construct larger-scale\nphotoelectric devices."
    },
    {
        "anchor": "Magnetic properties and field-driven dynamics of chiral domain walls in\n  epitaxial Pt/Co/Au$_x$Pt$_{1-x}$ trilayers: Chiral domain walls in ultrathin perpendicularly magnetised layers have a\nN\\'{e}el structure stabilised by a Dzyaloshinskii-Moriya interaction (DMI) that\nis generated at the interface between the ferromagnet and a heavy metal.\nDifferent heavy metals are required above and below a ferromagnetic film in\norder to generate the structural inversion asymmetry needed to ensure that the\nDMI arising at the two interfaces does not cancel. Here we report on the\nmagnetic properties of epitaxial Pt/Co/Au$_x$Pt$_{1-x}$ trilayers grown by\nsputtering onto sapphire substrates with 0.6 nm thick Co. As $x$ rises from 0\nto 1 a structural inversion asymmetry is generated. We characterise the\nepilayer structure with x-ray diffraction and cross-sectional transmission\nelectron microscopy, revealing (111) stacking. The saturation magnetization\nfalls as the proximity magnetisation in Pt is reduced, whilst the perpendicular\nmagnetic anisotropy $K_\\mathrm{u}$ rises. The micromagnetic DMI strength $D$\nwas determined using the bubble expansion technique and also rises from a\nnegligible value when $x=0$ to $\\sim 1$ mJ/m$^2$ for $x = 1$. The depinning\nfield at which field-driven domain wall motion crosses from the creep to the\ndepinning regime rises from $\\sim 40$ to $\\sim 70$ mT, attributed to greater\nspatial fluctuations of the domain wall energy with increasing Au\nconcentration. Meanwhile, the increase in DMI causes the Walker field to rise\nfrom $\\sim 10$ to $\\sim 280$ mT, meaning that only in the $x = 1$ sample is the\nsteady flow regime accessible. The full dependence of domain wall velocity on\ndriving field bears little resemblance to the prediction of a simple\none-dimensional model, but can be described very well using micromagnetic\nsimulations with a realistic model of disorder. These reveal a rise in Gilbert\ndamping as $x$ increases.",
        "positive": "High quality c-axis oriented ZnO thin-film obtained at very low\n  pre-heating temperature: Highly oriented ZnO thin-film has been obtained at a very low pre-heating\ntemperature, with the spin-coating sol-gel technique. The dependence of the\nc-axis orientation on the pre-heating temperature has been studied with\nexperimental design and response surface techniques to optimize the deposition\nprocess with respect to c-axis orientation, and surface uniformity. The\noptimization variables selected for this study are: pre-heating temperature,\nspin-coating speed and number of coating layers. The films are probed with\nX-ray diffraction and electron microscopy."
    },
    {
        "anchor": "Analysis of the Heyd-Scuseria-Ernzerhof density functional parameter\n  space: The Heyd-Scuseria-Ernzerhof (HSE) density functionals are popular for their\nability to improve the accuracy of standard semilocal functionals such as\nPerdew-Burke-Ernzerhof (PBE), particularly for semiconductor band gaps. They\nalso have a reduced computational cost compared to hybrid functionals, which\nresults from the restriction of Fock exchange calculations to small\ninter-electron separations. These functionals are defined by an overall\nfraction of Fock exchange and a length scale for exchange screening. We\nsystematically examine this two-parameter space to assess the performance of\nhybrid screened exchange (sX) functionals and to determine a balance between\nimproving accuracy and reducing the screening length, which can further reduce\ncomputational costs. Three parameter choices emerge as useful: \"sX-PBE\" is an\napproximation to the sX-LDA screened exchange density functionals based on the\nlocal density approximation (LDA); \"HSE12\" minimizes the overall error over all\ntests performed; and \"HSE12s\" is a range-minimized functional that matches the\noverall accuracy of the existing HSE06 parameterization but reduces the Fock\nexchange length scale by half. Analysis of the error trends over parameter\nspace produces useful guidance for future improvement of density functionals.",
        "positive": "Dielectric properties of a two dimensional binary sytem with ellipse\n  inclusions: A two-dimensional binary composite system composed of ellipse inclusions and\na host medium is considered. Dielectric permittivity of the system is\ncalculated as a function of orientation angle, the volume fraction of the\ninclusions and their excentricity using the finite element method. It was\nobserved that both the orientation of the inclusions in the field and their\nexcentricity have significant effects on the dielectric permittivity."
    },
    {
        "anchor": "Solitons in graphene: In this paper we demonstrate the direct evidence of solitons in graphene by\nmeans of molecular dynamics simulations and mathematical analysis. It shows\nvarious solitons emerge in the graphene flakes with two different chiralities\nby cooling procedures. They are in-plane longitudinal and transverse solitons.\nTheir propagations and collisions are studied in details. A soliton solution is\nderived by making several valid simplifications. We hope it shed light on\nunderstanding the unusual thermal properties of graphene.",
        "positive": "Raman spectrum of 1T'-WTe2 under tensile strain: A first-principles\n  prediction: Monolayer WTe2 attracts rapidly growing interests for its large-gap quantum\nspin Hall effect,which enables promising apllications in flexible logic\ndevices. Due to one-dimensional W-W chains,1T'-WTe2 exhibits unique anisotropic\nstructure and promising properties, which can be modified by simply applying\nstrains. Based on the first-principles simulations, we show that phonon branch\nundergoes soft down to negative frequency at special q points under different\ncritical strains, i.e., epsilon_a = 11.55 percent along a-axis (with W-W\nchains) direction, epsilon_b = 7.0 percent along b-axis direction and\nepsilon_ab = 8.44 percent along biaxial direction. Before each critical strain,\nthe Raman-shift of A1_g, A3_g, and A4_g modes, corresponding to the main peaks\nin Raman spectra of 1T'-WTe2 , shows anisotropic response to uniaxial strain\nbut most sensitive to biaxial strain. Interestingly, we find that the frequency\nshift of A3_g mode show parabolic characters of strained 1T'-WTe2, then we\nsplit it into two parts and it shows a Raman-shift transition at about 5\npercent strains. While for the A1_g and A4_g modes,the frequencies change\nlinearly. Through careful structure and vibration analysis, we try to explain\nthese Raman irregularity in strained 1T'-WTe2."
    },
    {
        "anchor": "Temperature controlled motion of an antiferromagnet-ferromagnet\n  interface within a dopant-graded FeRh epilayer: Chemically ordered B2 FeRh exhibits a remarkable\nantiferromagnetic-ferromagnetic phase transition that is first order. It thus\nshows phase coexistence, usually by proceeding though nucleation at random\ndefect sites followed by propagation of phase boundary domain walls. The\ntransition occurs at a temperature that can be varied by doping other metals\nonto the Rh site. We have taken advantage of this to yield control over the\ntransition process by preparing an epilayer with oppositely directed doping\ngradients of Pd and Ir throughout its height, yielding a gradual transition\nthat occurs between 350~K and 500~K. As the sample is heated, a horizontal\nantiferromagnetic-ferromagnetic phase boundary domain wall moves gradually up\nthrough the layer, its position controlled by the temperature. This mobile\nmagnetic domain wall affects the magnetisation and resistivity of the layer in\na way that can be controlled, and hence exploited, for novel device\napplications.",
        "positive": "Dislocation mutual interactions mediated by mobile impurities and the\n  conditions for plastic instabilities: Matallic alloys, such as Al or Cu, or mild steel, display plastic\ninstabilities in a well defined range of temperatures and deformation rates, a\nphenomenon known as the Portevin-Le Chatelelier (PLC) effect. The stick-slip\nbehavior, or serration, typical of this effect is due to the discontinuous\nmotion of dislocations as they interact with solute atoms. Here we study a\nsimple model of interacting dislocations and show how the classical Einstein\nfluctuation-dissipation relation can be used to define the temperature in a\nrange of model parameters and to construct a phase diagram of serration that\ncan be compared to experimental results. Furthermore, performing analytical\ncalculations and numerically integrating the equations of motion, we clarify\nthe crucial role played by dislocation mutual interactions in serration."
    },
    {
        "anchor": "Does P-type Ohmic Contact Exist in WSe2-metal Interfaces?: Formation of low-resistance metal contacts is the biggest challenge that\nmasks the intrinsic exceptional electronic properties of 2D WSe2 devices. We\npresent the first comparative study of the interfacial properties between ML/BL\nWSe2 and Sc, Al, Ag, Au, Pd, and Pt contacts by using ab initio energy band\ncalculations with inclusion of the spin-orbital coupling (SOC) effects and\nquantum transport simulations. The interlayer coupling tends to reduce both the\nelectron and hole Schottky barrier heights (SBHs) and alters the polarity for\nWSe2-Au contact, while the SOC chiefly reduces the hole SBH. In the absence of\nthe SOC, Pd contact has the smallest hole SBH with a value no less than 0.22\neV. Dramatically, Pt contact surpasses Pd contact and becomes p-type Ohmic or\nquasi-Ohmic contact with inclusion of the SOC. Our study provides a theoretical\nfoundation for the selection of favorable metal electrodes in ML/BL WSe2\ndevices.",
        "positive": "Unraveling the Unconventional Order of a High-Mobility\n  Indacenodithiophene-Benzothiadiazole Copolymer: A new class of donor-acceptor (D-A) copolymers found to produce high charge\ncarrier mobilities competitive with amorphous silicon ($> 1\ncm^{2}V^{-1}s^{-1}$) exhibits the puzzling microstructure of substantial local\norder, however lacking long-range order and crystallinity previously deemed\nnecessary for achieving high mobility. Here, we demonstrate the application of\nlow-dose transmission electron microscopy to image and quantify the nanoscale\nand mesoscale organization of an archetypal D-A copolymer across areas\ncomparable to electronic devices (~ $9 {\\mu}m^{2}$). The local structure is\nspatially resolved by mapping the backbone (001) spacing reflection, revealing\nnanocrystallites of aligned polymer chains over nearly the entire film.\nAnalysis of the nanoscale structure of its ordered domains suggests significant\nshort- and medium-range order and preferential grain boundary orientations.\nMoreover, we provide insights into the rich, interconnected mesoscale\norganization of this new family of D-A copolymers by analysis of the local\norientational spatial autocorrelations."
    },
    {
        "anchor": "Direct spectroscopic observation of a shallow hydrogen-like donor state\n  in insulating SrTiO$_{3}$: We present a direct spectroscopic observation of a shallow hydrogen-like\nmuonium state in SrTiO$_3$ which confirms the theoretical prediction that\ninterstitial hydrogen may act as a shallow donor in this material. The\nformation of this muonium state is temperature dependent and appears below\n$\\sim 70$ K. From the temperature dependence we estimate an activation energy\nof $\\sim 50$ meV in the bulk and $\\sim 23$ meV near the free surface. The field\nand directional dependence of the muonium precession frequencies further\nsupports the shallow impurity state with a rare example of a fully anisotropic\nhyperfine tensor. From these measurements we determine the strength of the\nhyperfine interaction and propose that the muon occupies an interstitial site\nnear the face of the oxygen octahedron in SrTiO$_3$. The observed shallow donor\nstate provides new insight for tailoring the electronic and optical properties\nof SrTiO$_{3}$-based oxide interface systems.",
        "positive": "Light-induced Magnetic Phase Transition in van der Waals\n  Antiferromagnets: Based on a simple tight-binding model, we propose a general theory of\nlight-induced magnetic phase transition (MPT) in antiferromagnets based on the\ngeneral conclusion that the bandgap of antiferromagnetic (AFM) phase is usually\nlarger than that of ferromagnetic (FM) one in a given system. Light-induced\nelectronic excitation prefers to stabilize the FM state over the AFM one, and\nonce the critical photocarrier concentration ({\\alpha}_c) is reached, an MPT\nfrom AFM phase to FM phase takes place. This theory has been confirmed by\nperforming first-principles calculations on a series of two-dimensional (2D)\nvan der Waals (vdW) antiferromagnets and a linear relationship between\n{\\alpha}_c and the intrinsic material parameters is obtained. Importantly, our\nconclusion is still valid even considering the strong exciton effects during\nphotoexcitation. Our general theory provides new ideas to realize reversible\nread-write operations for future memory devices."
    },
    {
        "anchor": "Efficient Spin Injection into Silicon and the Role of the Schottky\n  Barrier: Implementing spin functionalities in Si, and understanding the fundamental\nprocesses of spin injection and detection, are the main challenges in\nspintronics. Here we demonstrate large spin polarizations at room temperature,\n34% in n-type and 10% in p-type degenerate Si bands, using a narrow Schottky\nand a SiO2 tunnel barrier in a direct tunneling regime. Furthermore, by\nincreasing the width of the Schottky barrier in non-degenerate p-type Si, we\nobserved a systematic sign reversal of the Hanle signal in the low bias regime.\nThis dramatic change in the spin injection and detection processes with\nincreased Schottky barrier resistance may be due to a decoupling of the spins\nin the interface states from the bulk band of Si, yielding a transition from a\ndirect to a localized state assisted tunneling. Our study provides a deeper\ninsight into the spin transport phenomenon, which should be considered for\nelectrical spin injection into any semiconductor.",
        "positive": "Enhanced Raman and photoluminescence response in monolayer MoS$_2$ due\n  to laser healing of defects: Bound quasiparticles, negatively charged trions and neutral excitons, are\nassociated with the direct optical transitions at the K-points of the Brillouin\nzone for monolayer MoS$_2$. The change in the carrier concentration,\nsurrounding dielectric constant and defect concentration can modulate the\nphotoluminescence and Raman spectra. Here we show that exposing the monolayer\nMoS$_2$ in air to a modest laser intensity for a brief period of time enhances\nsimultaneously the photoluminescence (PL) intensity associated with both trions\nand excitons, together with $\\sim$ 3 to 5 times increase of the Raman intensity\nof first and second order modes. The simultaneous increase of PL from trions\nand excitons cannot be understood based only on known-scenario of depletion of\nelectron concentration in MoS$_2$ by adsorption of O$_2$ and H$_2$O molecules.\nThis is explained by laser induced healing of defect states resulting in\nreduction of non-radiative Auger processes. This laser healing is corroborated\nby an observed increase of intensity of both the first order and second order\n2LA(M) Raman modes by a factor of $\\sim$ 3 to 5. The A$_{1g}$ mode hardens by\n$\\sim$ 1.4 cm$^{-1}$ whereas the E$^1_{2g}$ mode softens by $\\sim$ 1 cm$^{-1}$.\nThe second order 2LA(M) Raman mode at $\\sim$ 440 cm$^{-1}$ shows an increase in\nwavenumber by $\\sim$ 8 cm$^{-1}$ with laser exposure. These changes are a\ncombined effect of change in electron concentrations and oxygen-induced lattice\ndisplacements."
    },
    {
        "anchor": "Crossover from Positive to Negative Interlayer Magnetoresistance in\n  Multilayer Massless Dirac Fermion System with Non-Vertical Interlayer\n  Tunneling: We present a theoretical description of the interlayer magnetoresistance in\nthe layered Dirac fermion system with the application to the organic conductor\n\\alpha-(BEDT-TTF)_2I_3 under pressure. Assuming a non-vertical interlayer\ntunneling and including higher Landau level effects we calculate the interlayer\nconductivity using the Kubo formula.We propose a physical picture of the\nexperimentally observed crossover from the negative interlayer\nmagnetoresistance, where the Dirac fermion zero-energy Landau level plays a\ncentral role, to the positive interlayer magnetoresistance that is the\nconsequence of the Landau level mixing effect upon non-vertical interlayer\nhopping. The crossover magnetic field depends on the Landau level broadening\nfactor and can be used to determine the Dirac fermion Landau level energy\nspectrum.",
        "positive": "Surface Rearrangement and Evaporation Kinetics of Supported Gold\n  Nanoparticle Catalysts: Heterogeneous catalysts consisting of supported metallic nanoparticles\ntypically derive exceptional catalytic activity from their large proportion of\nunder-coordinated surface sites which promote adsorption of reactant molecules.\nSimultaneously, these high energy surface configurations are unstable, leading\nto nanoparticle growth or degradation, and eventually a loss of catalytic\nactivity. Surface morphology of catalytic nanoparticles is paramount to\ncatalytic activity, selectivity, as well as degradation rates, however, it is\nwell-known that harsh reaction conditions can cause the surface structure to\nchange. Still, limited research has focused on understanding the link between\nnanoparticle surface facets and degradation rates or mechanisms. Here, we study\na model Au supported catalyst system over a range of temperatures using a\ncombination of \\textit{in situ} Transmission Electron Microscopy, kinetic Monte\nCarlo simulations, and density functional theory calculations to establish an\natomistic picture of how variations in surface structures and atomic\ncoordination environments lead to shifting evolution mechanisms as a function\nof temperature. By combining experimental results, which yield direct\nobservation of dynamic shape changes and particle evaporation rates, with\ncomputational techniques, which enable understanding the fundamental\nthermodynamics and kinetics of nanoparticle evolution, we illustrate a two-step\nevolution mechanism in which mobile adatoms form through desorption from\nlow-coordination facets and subsequently evaporate off the particle surface. By\nunderstanding the role of temperature in the competition between surface\ndiffusion and evaporation, we are able to show how individual atomic movements\nlead to particle-scale morphological changes, and rationalize why evaporation\nrates vary between particles in a system of nearly identical nanoparticles."
    },
    {
        "anchor": "Unidirectional anisotropy in cubic FeGe with antisymmetric\n  spin-spin-coupling: We report strong unidirectional anisotropy in bulk polycrystalline B20 FeGe\nmeasured by ferromagnetic resonance spectroscopy. Bulk and micron-sized samples\nwere produced and analytically characterized. FeGe is a B20 compound with\ninherent Dzyaloshinskii-Moriya interaction. Lorenz microscopy confirms a\nskyrmion lattice at $190 \\; \\text{K}$ in a magnetic field of 150 mT.\nFerromagnetic resonance was measured at $276 \\; \\text{K} \\pm 1 \\; \\text{K}$,\nnear the Curie temperature. Two resonance modes were observed, both exhibit a\nunidirectional anisotropy of $K=1153 \\; \\text{J/m}^3 \\pm 10 \\; \\text{J/m}^3$ in\nthe primary, and $K=28 \\; \\text{J/m}^3 \\pm 2 \\; \\text{J/m}^3$ in the secondary\nmode, previously unknown in bulk ferromagnets. Additionally, about 25 standing\nspin wave modes are observed inside a micron-sized FeGe wedge, measured at room\ntemperature ($\\sim \\; 293$ K). These modes also exhibit unidirectional\nanisotropy.",
        "positive": "Non-local plasticity effects on notch fracture mechanics: We investigate the influence of gradient-enhanced dislocation hardening on\nthe mechanics of notch-induced failure. The role of geometrically necessary\ndislocations (GNDs) in enhancing cracking is assessed by means of a\nmechanism-based strain gradient plasticity theory. Both stationary and\npropagating cracks from notch-like defects are investigated through the finite\nelement method. A cohesive zone formulation incorporating monotonic and cyclic\ndamage contributions is employed to address both loading conditions.\nComputations are performed for a very wide range of length scale parameters and\nnumerous geometries are addressed, covering the main types of notches. Results\nreveal a strong influence of the plastic strain gradients in all the scenarios\nconsidered. Transitional combinations of notch angle, radius and length scale\nparameter are identified that establish the regimes of GNDs-relevance, laying\nthe foundations for the rational application of gradient plasticity models in\ndamage assessment of notched components."
    },
    {
        "anchor": "Statistical coarse-graining as an approach to multiscale problems in\n  magnetism: Multiscale phenomena which include several processes occuring simultaneously\nat different length scales and exchanging energy with each other, are\nwidespread in magnetism. These phenomena often govern the magnetization\nreversal dynamics, and their correct modeling is important. In the present\npaper, we propose an approach to multiscale modeling of magnets, applying the\nideas of coarse graining. We have analyzed the choice of the weighting function\nused in coarse graining, and propose an optimal form for this function. Simple\ntests provide evidence that this approach may be useful for modeling of\nrealistic magnetic systems.",
        "positive": "Capillary flow of a suspension in the presence of discontinuous shear\n  thickening: The rheology of suspensions showing discontinuous shear thickening (DST) is\nwell documented in conventional rheometer with rotating tools, but their study\nin capillary flow is still lacking. We present results obtained in a homemade\ncapillary rheometer working in an imposed pressure regime. We show that the\nshape of the experimental curve giving the volume flow rate versus the wall\nstress in a capillary can be qualitatively reproduced from the curve obtained\nin rotational geometry at imposed stress but instead of a sharp decrease of the\nvolume flow rate observed at a critical stress, this transposition predicts a\nprogressive decrease in flow rate. The Wyart-Cates theory is used to reproduce\nthe stress-shear rate curve obtained in rotational geometry and then applied to\npredict the volume flow rate at imposed pressure. The theoretical curve\npredicts a total stop of the flow at high stress, whereas experimentally it\nremains constant. We propose a modification of the theory which, by taking into\naccount the relaxation of the frictional contacts in the absence of shear rate,\nwell predicts the high stress behavior. We also hypothesized that the DST\ntransition propagates immediately inside the capillary, once the wall shear\nstress has reached its critical value: $\\tau_R=\\tau_c$, even if the internal\nshear stress $\\tau(r<R)$ is below the critical one. In this way the whole\nexperimental curve can be well reproduced by the modified W-C model."
    },
    {
        "anchor": "Localization of Fe d-states in Ni-Fe-Cu alloys and implications for\n  ultrafast demagnetization: Ni$_{80}$Fe$_{20}$ (Py) and Py-Cu exhibit intriguing ultrafast\ndemagnetization behavior, where the Ni magnetic moment shows a delayed response\nrelative to the Fe [S. Mathias et al., PNAS {\\bf 109}, 4792 (2012)]. To unravel\nthe mechanism responsible for this behavior, we have studied Py-Cu alloys for a\nwide range of Cu concentrations using X-ray magnetic circular dichroism (XMCD).\nThe magnetic moments of Fe and Ni are found to respond very differently to Cu\nalloying: Fe becomes a strong ferromagnet in Py, with the magnetic moment\nlargely unaffected by Cu alloying. In contrast, the Ni magnetic moment\ndecreases continuously with increasing Cu concentration. Our results are\ncorroborated by ab-initio calculations of the electronic structure, which we\ndiscuss in the framework of virtual bound states (VBSs). For high Cu\nconcentrations, Ni exhibits VBSs below the Fermi level, which are likely\nresponsible for an increased orbital/spin magnetic ratio at high Cu\nconcentrations. Fe exhibits VBSs in the minority band, approximately 1 eV above\nthe Fermi level in pure Py, that move closer to the Fermi level upon Cu\nalloying. A strong interaction between the VBSs and excited electrons above the\nFermi level enhances the formation of localized magnons at Fe sites, which\nexplains the different behavior between Fe and Ni during ultrafast\ndemagnetization.",
        "positive": "A Novel Temperature-Induced Magnetization Transition in Pt/Co/Pt\n  Sandwiches: It is found in the Pt/Co/Pt(111) sandwiches that perpendicular magnetic\nanisotropy weakens associated with the dramatic magnetization enhancement as\nthe temperature decreases below a critical temperature, T_cri, which increases\nwith the Pt overlayer thickness t_Pt. For the sandwich with enough thick Pt\noverlayer, it trends to an unusual state with weak perpendicular magnetic\nanisotropy in the absence of obvious easy direction behavior at low\ntemperature. It suggests that Pt is more significantly polarized in the film\nwith thicker Pt overlayer. The results reveal the strong influence of both\nthick nonmagnetic coverage and temperature on the electronic structure of the\nPt/Co/Pt(111) sandwich."
    },
    {
        "anchor": "Stochastic Heterostructures in B/N-Doped Carbon Nanotubes: Carbon nanotubes are one-dimensional and very narrow. These obvious facts\nimply that under doping with boron and nitrogen, microscopic doping\ninhomogeneity is much more important than for bulk semiconductors. We consider\nthe possibility of exploiting such fluctuations to create interesting devices.\nUsing self-consistent tight-binding (SCTB), we study heavily doped highly\ncompensated nanotubes, revealing the spontaneous formation of structures\nresembling chains of random quantum dots, or nano-scale diode-like elements in\nseries. We also consider truly isolated impurities, revealing simple scaling\nproperties of bound state sizes and energies.",
        "positive": "Spin gaps and spin-flip energies in density-functional theory: Energy gaps are crucial aspects of the electronic structure of finite and\nextended systems. Whereas much is known about how to define and calculate\ncharge gaps in density-functional theory (DFT), and about the relation between\nthese gaps and derivative discontinuities of the exchange-correlation\nfunctional, much less is know about spin gaps. In this paper we give\ndensity-functional definitions of spin-conserving gaps, spin-flip gaps and the\nspin stiffness in terms of many-body energies and in terms of single-particle\n(Kohn-Sham) energies. Our definitions are as analogous as possible to those\ncommonly made in the charge case, but important differences between spin and\ncharge gaps emerge already on the single-particle level because unlike the\nfundamental charge gap spin gaps involve excited-state energies. Kohn-Sham and\nmany-body spin gaps are predicted to differ, and the difference is related to\nderivative discontinuities that are similar to, but distinct from, those\nusually considered in the case of charge gaps. Both ensemble DFT and\ntime-dependent DFT (TDDFT) can be used to calculate these spin discontinuities\nfrom a suitable functional. We illustrate our findings by evaluating our\ndefinitions for the Lithium atom, for which we calculate spin gaps and spin\ndiscontinuities by making use of near-exact Kohn-Sham eigenvalues and,\nindependently, from the single-pole approximation to TDDFT. The many-body\ncorrections to the Kohn-Sham spin gaps are found to be negative, i.e., single\nparticle calculations tend to overestimate spin gaps while they underestimate\ncharge gaps."
    },
    {
        "anchor": "Formation of nanoribbons by carbon atoms confined in a single-walled\n  carbon nanotube -- A molecular dynamics study: Carbon nanotubes can serve as one-dimensional nanoreactors for the in-tube\nsynthesis of various nanostructures. Experimental observations have shown that\nchains, inner tubes, or nanoribbons can grow by the thermal decomposition of\norganic/organometallic molecules encapsulated in carbon nanotubes. The result\nof the process depends on the temperature, the diameter of the nanotube, and\nthe type and amount of material introduced inside the tube. Nanoribbons are\nparticularly promising materials for nanoelectronics. Motivated by recent\nexperimental results observing the formation of carbon nanoribbons inside\ncarbon nanotubes, molecular dynamics calculations were performed with the open\nsource LAMMPS code to investigate the reactions between carbon atoms confined\nwithin a single-walled carbon nanotube. Our results show that the interatomic\npotentials behave differently in quasi-one-dimensional simulations of\nnanotube-confined space than in three-dimensional simulations. In particular,\nthe Tersoff potential performs better than the widely used Reactive Force Field\npotential in describing the formation of carbon nanoribbons inside nanotubes.\nWe also found a temperature window where the nanoribbons were formed with the\nfewest defects, i.e., with the largest flatness and the most hexagons, which is\nin agreement with the experimental temperature range.",
        "positive": "Effect of local environment on moment formation in iron silicides: The effect of local environment on the formation of magnetic moments on Fe\natoms in iron silicides are studied by combination of ab initio and model\ncalculations. The suggested model includes all Fe d- and Si p-orbitals,\nintra-atomic Coulomb interactions, inter-atomic Fe-Fe exchange and hopping of\nelectrons to nearest and next nearest neighboring atoms and takes into account\nall symmetries within the Slater-Koster scheme. The parameters of the model are\nfound from the requirement that self-consistent moments on atoms and density of\nstates found from ab initio and model calculations within the Hartree-Fock\napproximation are close to each other as much as possible. Contrary to the\ncommonly accepted statement that an increase of the Si concentration within\nnearest environment of Fe atoms in the ordered Fe3Si and FexSi1-x alloys leads\nto a decrease of Fe magnetic moment we find that a crucial role in the\nformation of magnetic moments is played by second coordination sphere of Fe\natoms. Particularly, the Fe atoms have higher magnetic moments in amorphous\nfilms compared to the epitaxial ones due to decrease in the number of\niron-atoms in the next nearest environment. Both our model and ab initio\ncalculations confirm existence of known spin crossover with pressure and\npredict second crossover at higher pressure"
    },
    {
        "anchor": "2DMatPedia: An open computational database of two-dimensional materials\n  from top-down and bottom-up approaches: Two-dimensional (2D) materials have been a hot research topic in the last\ndecade, due to novel fundamental physics in the reduced dimension and appealing\napplications. Systematic discovery of functional 2D materials has been the\nfocus of many studies. Here, we present a large dataset of 2D materials, with\nmore than 6,000 monolayer structures, obtained from both top-down and bottom-up\ndiscovery procedures. First, we screened all bulk materials in the database of\nMaterials Project for layered structures by a topology-based algorithm, and\ntheoretically exfoliate them into monolayers. Then, we generated new 2D\nmaterials by chemical substitution of elements in known 2D materials by others\nfrom the same group in the periodic table. The structural, electronic and\nenergetic properties of these 2D materials are consistently calculated, to\nprovide a starting point for further material screening, data mining, data\nanalysis and artificial intelligence applications. We present the details of\ncomputational methodology, data record and technical validation of our publicly\navailable data (http://www.2dmatpedia.org/).",
        "positive": "Local polar fluctuations in lead halide perovskite crystals: Hybrid lead-halide perovskites have emerged as an excellent class of\nphotovoltaic materials. Recent reports suggest that the organic molecular\ncation is responsible for local polar fluctuations that inhibit carrier\nrecombination. We combine low frequency Raman scattering with first-principles\nmolecular dynamics (MD) to study the fundamental nature of these local polar\nfluctuations. Our observations of a strong central peak in both hybrid\n(CH$_3$NH$_3$PbBr$_3$) and all-inorganic (CsPbBr$_3$) lead-halide perovskites\nshow that anharmonic, local polar fluctuations are intrinsic to the general\nlead-halide perovskite structure, and not unique to the dipolar organic cation.\nMD simulations show that head-to-head Cs motion coupled to Br face expansion,\non a few hundred femtosecond time scale, drives the local polar fluctuations in\nCsPbBr$_3$."
    },
    {
        "anchor": "Compositional uniformity, domain patterning and the mechanism underlying\n  nano-chessboard arrays: We propose that systems exhibiting compositional patterning at the nanoscale,\nso far assumed to be due to some kind of ordered phase segregation, can be\nunderstood instead in terms of coherent, single phase ordering of minority\nmotifs, caused by some constrained drive for uniformity. The essential features\nof this type of arrangements can be reproduced using a superspace construction\ntypical of uniformity-driven orderings, which only requires the knowledge of\nthe modulation vectors observed in the diffraction patterns. The idea is\ndiscussed in terms of a simple two dimensional lattice-gas model that simulates\na binary system in which the dilution of the minority component is favored.\nThis simple model already exhibits a hierarchy of arrangements similar to the\nexperimentally observed nano-chessboard and nano-diamond patterns, which are\ndescribed as occupational modulated structures with two independent modulation\nwave vectors and simple step-like occupation modulation functions.",
        "positive": "Strain Engineering of Spin and Rashba properties in Group-III\n  Monochalcogenide MX (M=Ga, In and X=S, Se, Te) Monolayer: In this paper, spin properties of monolayer MX (M=Ga, In and X=S, Se, Te) in\nthe presence of strain are studied. Density functional theory is used to\ninvestigate spin properties. The strain changes modification of bandgap due to\nspin-orbit coupling, the results indicate the spin-orbit coupling has a higher\neffect in the compressive regime. Also, spin splitting in the conduction and\nvalence bands respect to strain are compared for six materials. The location of\nconduction band minimum (CBM) imposed a type of spin properties. These\nmaterials with mirror symmetry can display the Rashba effect while M valley is\nlocated at CBM. Strain tunes the conduction band minimum in three valleys (K, M\nand $\\Gamma$ valleys) and determines which spin effect (spin splitting, Rashba\nsplitting or no spin splitting) has occurred in each strain for every material.\nLastly, the relation between the Rashba parameter and the atomic mass is\nexplored and it is observed that there is a linear correlation between atomic\nmass and Rashba coefficient."
    },
    {
        "anchor": "Helical Organic and Inorganic Polymers: Despite being a staple of synthetic plastics and biomolecules, helical\npolymers are scarcely studied with Gaussian-basis-set {\\it ab initio}\nelectron-correlated methods on an equal footing with molecules. This article\nintroduces an {\\it ab initio} second-order many-body Green's-function [MBGF(2)]\nmethod with nondiagonal, frequency-dependent Dyson self-energy for infinite\nhelical polymers using screw-axis-symmetry-adapted Gaussian-spherical-harmonics\nbasis functions. Together with the Gaussian-basis-set density-functional theory\nfor energies, analytical atomic forces, translational-period force, and\nhelical-angle force, it can compute correlated energy, quasiparticle energy\nbands, structures, and vibrational frequencies of an infinite helical polymer,\nwhich smoothly converge at the corresponding oligomer results. These methods\ncan handle incommensurable structures, which have an infinite translational\nperiod and are hard to characterize by any other method, just as efficiently as\ncommensurable structures. We apply these methods to polyethylene ($2/1$ helix),\npolyacetylene (Peierls' system), and polytetrafluoroethylene ($13/6$ helix) to\nestablish the quantitative accuracy of MBGF(2)/cc-pVDZ in simulating their\n(angle-resolved) ultraviolet photoelectron spectra, and of B3LYP/cc-pVDZ or\n6-31G** in reproducing their structures, infrared and Raman band positions,\nphonon dispersions, and (coherent and incoherent) inelastic neutron scattering\nspectra. We then predict the same properties for infinitely catenated chains of\nnitrogen or oxygen and discuss their possible metastable existence under\nambient conditions. They include planar zigzag polyazene (N$_2$)$_x$ (Peierls'\nsystem), $11/3$-helical isotactic polyazane (NH)$_x$, $9/4$-helical isotactic\npolyfluoroazane (NF)$_x$, and $7/2$-helical polyoxane (O)$_x$ as potential\nhigh-energy-density materials.",
        "positive": "In-situ comparison of interface instability of basal and edge planes\n  during unidirectional growth of sea ice: The unique anisotropy of ice has endowed sea ice growth a peculiar and\nattractive subject from both fundamental and applied viewpoints. The distinct\ngrowth behaviors between edge and basal plane of ice are one of the central\ntopics in ice growth. And the unidirectional freezing pattern stems from\nperturbations of both basal and edge planes. To date there is no direct\ncomparison of unidirectional freezing behavior between basal and edge plane\nice. Here, we in-situ investigate the planar instability as well as the\nunidirectional freezing pattern of basal and edge planes of ice by a design of\nparallel freezing samples with specified ice orientations in a NaCl solution as\na modeled sea water. The planar instability is discussed via neutral stability\ncurves with surface tension anisotropy for both basal and edge plane ice. For\nthe first time, we realize the simultaneous observation of solid/liquid\ninterfaces of basal and edge plane ice under the same set of freezing\nconditions. The results show that planar instability occurs faster for edge\nplane ice than basal plane ice. The time-lapse observations confirm a transient\ncompetitive interaction of perturbations between the basal and edge planes ice,\nwhich is explained by the anisotropic growth of perturbations in basal and edge\nplanes of ice. These experimental results provide a link between morphology\nevolution of unidirectional grown sea ice and different ice orientations and\nare suggested to enrich our understanding of sea ice growth as well as\ncrystallization pattern of other anisotropic materials."
    },
    {
        "anchor": "Determination of the universality class of crystal plasticity: Although scaling phenomena have long been documented in crystalline\nplasticity, the universality class has been difficult to identify due to the\nrarity of avalanche events, which require large system sizes and long times in\norder to accurately measure scaling exponents and functions. Here we present\ncomprehensive simulations of two-dimensional dislocation dynamics under shear,\nusing finite-size scaling to extract scaling exponents and the avalanche\nprofile scaling function from time-resolved measurements of slip-avalanches.\nOur results provide compelling evidence that both the static and dynamic\nuniversality classes are consistent with the mean-field interface depinning\nmodel.",
        "positive": "Elastic stability of Ga$_2$O$_3$: Addressing the $\u03b2$ to $\u03b1$\n  phase transition from first principles: Elastic and structural properties of $\\beta$-Ga$_2$O$_3$ and\n$\\alpha$-Ga$_2$O$_3$ are investigated from first principles. The full elastic\ntensors and elastic moduli of both phases at $0$ K are computed in the\nframework of semi-local density-functional theory. We determine mechanical\ninstabilities of $\\beta$-Ga$_2$O$_3$ by evaluating the full stiffness tensor\nunder load for a range of hydrostatic pressure values. While a phase transition\nfrom the $\\beta$ to $\\alpha$ phase is found to be energetically favored at\n$2.6$ GPa, we show that the $\\beta$ phase is only mechanically unstable for\nmuch higher pressures ($>30$ GPa), which agrees well with experimental results.\nOur employed approach is based on the Born stability criterion, is independent\nof crystal symmetry, and thus can be readily applied to different materials."
    },
    {
        "anchor": "Fluctuation-Dissipation-Theorem violation during the formation of a\n  colloidal-glass: The relationship between the conductivity and the polarization noise is\nmeasured in a gel as a function of frequency in the range $1Hz - 40Hz$. It is\nfound that at the beginning of the transition from a fluid like sol to a solid\nlike gel the fluctuation dissipation theorem is strongly violated. The\namplitude and the persistence time of this violation are decreasing functions\nof frequency. At the lowest frequencies of the measuring range it persists for\ntimes which are about 5% of the time needed to form the gel. This phenomenology\nis quite close to the recent theoretical predictions done for the violation of\nthe fluctuation dissipation theorem in glassy systems.",
        "positive": "Local minimum in effective pairpotentials: Pseudopotential theory\n  revisited: Local minimum appearing in the interionic pair interactions, when derived\nfrom local model pseudopotential, for Al (and some other polyvalent metals)\nremains as a long standing problem of clear understanding although some\nattempts are made by different authors. The origin of this feature of local\nminimum is systematically investigated in this article, considering both the\nchemical valence, Z, and the core radius, $R_{c}$ as variables. Ashcroft's\nempty core model is used to describe the interionic pair-potential, because, it\ndepends on these two parameters only. Results of this investigation show that\nmonovalent metals do not exhibit a local minimum at small $r$ but some\npolyvalent metals does where, the core radius plays the major role."
    },
    {
        "anchor": "Monte Carlo simulation of equilibrium L1_0 ordering in FePt\n  nanoparticles: First, second and third nearest neighbor mixing potentials for FePt alloys,\nwere calculated from first principles using a Connolly-Williams approach. Using\nthe mixing potentials obtained in this manner, the dependency of equilibrium\nL1_0 ordering on temperature was studied for bulk and for a spherical\nnanoparticle with 3.5nm diameter at equiatomic composition by use of Monte\nCarlo simulation and the analytical ring approximation. The calculated\norder-disorder temperature for bulk (1495-1514 K) was in relatively good\nagreement (4% error) with the experimental value (1572K). For nanoparticles of\nfinite size, the (long range) order parameter changed continuously from unity\nto zero with increasing temperature. Rather than a discontinuity indicative of\na phase transition we obtained an inflection point in the order as a function\nof temperature. This inflection point occurred at a temperature below the bulk\nphase transition temperature and which decreased as the particle size\ndecreased. Our calculations predict that 3.5nm diameter particles in\nconfigurational equilibrium at 600 C (a typical annealing temperature for\npromoting L1_0 ordering) have an L1_0 order parameter of 0.83 (compared to a\nmaximum possible value equal to unity). According to our investigations, the\nexperimental absence of (relatively) high L1_0 order in 3.5nm diameter\nnanoparticles annealed at 600 C or below is primarily a problem of kinetics\nrather than equilibrium",
        "positive": "What is the speed limit of martensitic transformations?: Structural martensitic transformations enable various applications, which\nrange from high stroke actuation and sensing to energy efficient magnetocaloric\nrefrigeration and thermomagnetic energy harvesting. All these emerging\napplications benefit from a fast transformation, but up to now the speed limit\nof martensitic transformations has not been explored. Here, we demonstrate that\na martensite to austenite transformation can be completed in under ten\nnanoseconds. We heat an epitaxial Ni-Mn-Ga film with a laser pulse and use\nsynchrotron diffraction to probe the influence of initial sample temperature\nand overheating on transformation rate and ratio. We demonstrate that an\nincrease of thermal energy drives this transformation faster. Though the\nobserved speed limit of 2.5 x 10^{27} (Js)^{-1} per unit cell leaves plenty of\nroom for a further acceleration of applications, our analysis reveals that the\npractical limit will be the energy required for switching. Our experiments\nunveil that martensitic transformations obey similar speed limits as in\nmicroelectronics, which are expressed by the Margolus-Levitin theorem."
    },
    {
        "anchor": "Benchmarking Hydrogen-Helium Mixtures with QMC: Energetics, Pressures,\n  and Forces: An accurate understanding of the phase diagram of dense hydrogen and helium\nmixtures is a crucial component in the construction of accurate models of\nJupiter, Saturn, and Jovian extrasolar planets. Though DFT based first\nprinciples methods have the potential to provide the accuracy and computational\nefficiency required for this task, recent benchmarking in hydrogen has shown\nthat achieving this accuracy requires a judicious choice of functional, and a\nquantification of the errors introduced. In this work, we present a quantum\nMonte Carlo based benchmarking study of a wide range of density functionals for\nuse in hydrogen-helium mixtures at thermodynamic conditions relevant for Jovian\nplanets. Not only do we continue our program of benchmarking energetics and\npressures, but we deploy QMC based force estimators and use them to gain\ninsights into how well the local liquid structure is captured by different\ndensity functionals. We find that TPSS, BLYP and vdW-DF are the most accurate\nfunctionals by most metrics, and that the enthalpy, energy, and pressure errors\nare very well behaved as a function of helium concentration. Beyond this, we\nhighlight and analyze the major error trends and relative differences exhibited\nby the major classes of functionals, and estimate the magnitudes of these\neffects when possible.",
        "positive": "Nanoscale distribution of magnetic anisotropies in bimagnetic soft\n  core-hard shell MnFe$_2$O$_4$@CoFe$_2$O$_4$ nanoparticles: The nanoscale distribution of magnetic anisotropies was measured in\ncore@shell MnFe$_2$O$_4$@CoFe$_2$O$_4$ 7.0 nm particles using a combination of\nelement selective magnetic spectroscopies with different probing depths. As\nthis picture is not accessible by any other technique, emergent magnetic\nproperties were revealed. The coercive field is not constant in a whole\nnanospinel. The very thin (0.5 nm) CoFe$_2$O$_4$ hard shell imposes a strong\nmagnetic anisotropy to the otherwise very soft MnFe$_2$O$_4$ core: a large\ngradient in coercivity was measured inside the MnFe$_2$O$_4$ core with lower\nvalues close to the interface region, while the inner core presents a\nsubstantial coercive field (0.54 T) and a very high remnant magnetization (90%\nof the magnetization at saturation)."
    },
    {
        "anchor": "A linear-scaling algorithm for rapid computation of inelastic\n  transitions in the presence of multiple electron scattering: Strong multiple scattering of the probe in scanning transmission electron\nmicroscopy (STEM) means image simulations are usually required for quantitative\ninterpretation and analysis of elemental maps produced by electron energy-loss\nspectroscopy (EELS). These simulations require a full quantum-mechanical\ntreatment of multiple scattering of the electron beam, both before and after a\ncore-level inelastic transition. Current algorithms scale quadratically and can\ntake up to a week to calculate on desktop machines even for simple crystal unit\ncells and do not scale well to the nano-scale heterogeneous systems that are\noften of interest to materials science researchers. We introduce an algorithm\nwith linear scaling that typically results in an order of magnitude reduction\nin compute time for these calculations without introducing additional error and\ndiscuss approximations that further improve computational scaling for larger\nscale objects with modest penalties in calculation error. We demonstrate these\nspeed-ups by calculating the atomic resolution STEM-EELS map using the L-edge\ntransition of Fe, for of a nanoparticle 80 \\AA\\ in diameter in 16 hours, a\ncalculation that would have taken at least 80 days using a conventional\nmultislice approach.",
        "positive": "Characterization and Characteristics of mechanochemically synthesized\n  amorphous fast ionic conductor 50 SISOMO (50AgI-25Ag2O-25MoO3): Mechanochemically synthesized amorphous 50SISOMO [50AgI-25Ag_2O-25MoO_3] fast\nionic conductor shows high ionic conductivity of ~ 6x10^-3 {\\Omega}^-1 cm-1 at\nroom temperature. The highest ionic conductivity is achieved for 36 h milled\nsample, which is more than three orders of magnitude higher than that of\ncrystalline AgI at room temperature. The samples are thermally stable at least\nup to ~70 {\\deg}C. Thermoelectric power studies on 50 SISOMO amorphous fast\nionic conductors (a-SIC) have been carried out in the temperature range\n300-330K. Thermoelectric power (S) is found to vary linearly with the inverse\nof the absolute temperature, and can be expressed by the equation -S = [(0.19\n\\times 10^3/T) + 0.25] mV/K. The heat of transport (q*) of Ag+ ion i.e. 0.19 eV\nis nearly equal to the activation energy (E) i.e. 0.20 eV of Ag+ ion migration\ncalculated from the conductivity plots indicating that the material has an\naverage structure. This is also in consonance with earlier theories on heats of\ntransport of ions in ionic solids."
    },
    {
        "anchor": "Nucleation and Growth of bundles of Single-Wall Carbon Nanotubes\n  (C-SWNTs): the Benard-Marangoni Instability (BMI) model: A complete explanation of the synthesis of metal-catalyst nanoparticles, and\nthe subsequent nucleation and growth of bundles of C-SWNTs is introduced using\na novel model. It is shown that the synthesis process leads to the formation of\na liquid layer supersaturated in carbon surrounding each metallic-catalyst\nnanoparticle. The onset of a solutal B\\'enard-Marangoni instability and the\nsubsequent formation of patterns of hexagonal convection cells in the liquid\nlayer is predicted and quantified by linear and weakly nonlinear analyses. The\nnucleation and growth of a C-SWNT at the center of convection cell is\nexplained.",
        "positive": "Electron spin relaxation in graphene from a microscopic approach: Role\n  of electron-electron interaction: Electron spin relaxation in graphene on a substrate is investigated from the\nfully microscopic kinetic spin Bloch equation approach. All the relevant\nscatterings, such as the electron-impurity, electron--acoustic-phonon,\nelectron--optical-phonon, electron--remote-interfacial-phonon, as well as\nelectron-electron Coulomb scatterings, are explicitly included. Our study\nconcentrates on clean intrinsic graphene, where the spin-orbit coupling from\nthe adatoms can be neglected. We discuss the effect of the electron-electron\nCoulomb interaction on spin relaxation under various conditions. It is shown\nthat the electron-electron Coulomb scattering plays an important role in spin\nrelaxation at high temperature. We also find a significant increase of the spin\nrelaxation time for high spin polarization even at room temperature, which is\ndue to the Coulomb Hartree-Fock contribution-induced effective longitudinal\nmagnetic field. It is also discovered that the spin relaxation time increases\nwith the in-plane electric field due to the hot-electron effect, which is\ndifferent from the non-monotonic behavior in semiconductors. Moreover, we show\nthat the electron-electron Coulomb scattering in graphene is not strong enough\nto establish the steady-state hot-electron distribution in the literature and\nan alternative approximate one is proposed based on our computation."
    },
    {
        "anchor": "InAs nanocrystals with robust p-type doping: Robust control over the carrier type is fundamental for the fabrication of\nnanocrystal-based optoelectronic devices, such as the p-n homojunction, but\neffective incorporation of impurities in semiconductor nanocrystals and its\ncharacterization is highly challenging due to their small size. Herein, InAs\nnanocrystals, post-synthetically doped with Cd, serve as a model system for\nsuccessful p-type doping of originally n-type InAs nanocrystals, as\ndemonstrated in field-effect transistors (FETs). Advanced structural analysis,\nusing atomic resolution electron microscopy and synchrotron X-ray absorption\nfine structure spectroscopy reveal that Cd impurities reside near and on the\nnanocrystal surface acting as substitutional p-dopants replacing Indium.\nCommensurately, Cd-doped InAs FETs exhibited remarkable stability of their hole\nconduction, mobility, and hysteretic behavior over time when exposed to air,\nwhile intrinsic InAs NCs FETs were easily oxidized and their performance\nquickly declined. Therefore, Cd plays a dual role acting as a p-type dopant,\nand also protects the nanocrystals from oxidation, as evidenced directly by\nXray photoelectron spectroscopy measurements of air-exposed samples of\nintrinsic and Cd doped InAs NCs films. This study demonstrates robust p-type\ndoping of InAs nanocrystals, setting the stage for implementation of such doped\nnanocrystal systems in printed electronic devices.",
        "positive": "Observation of topological flat bands in the kagome semiconductor\n  Nb$_3$Cl$_8$: The destructive interference of wavefunctions in a kagome lattice can give\nrise to topological flat bands (TFBs) with a highly degenerate state of\nelectrons. Recently, TFBs have been observed in several kagome metals,\nincluding Fe$_3$Sn$_2$, FeSn, CoSn, and YMn$_6$Sn$_6$. Nonetheless, kagome\nmaterials that are both exfoliable and semiconducting are lacking, which\nseriously hinders their device applications. Herein, we show that Nb$_3$Cl$_8$,\nwhich hosts a breathing kagome lattice, is gapped out because of the absence of\ninversion symmetry, while the TFBs survive because of the protection of the\nmirror reflection symmetry. By angle-resolved photoemission spectroscopy\nmeasurements and first-principles calculations, we directly observe the TFB and\na moderate band gap in Nb$_3$Cl$_8$. By mechanical exfoliation, we successfully\nobtain monolayers of Nb$_3$Cl$_8$ and confirm that they are stable under\nambient conditions. In addition, our calculations show that monolayers of\nNb$_3$Cl$_8$ have a magnetic ground state, thus providing opportunities to\nstudy the interplay between geometry, topology, and magnetism."
    },
    {
        "anchor": "Boron Arsenide Heterostructures: Lattice-Matched Heterointerfaces, and\n  Strain Effects on Band Alignments and Mobility: BAs is III-V semiconductor with ultra-high thermal conductivity, but many of\nits electronic properties are unknown. This work applies predictive atomistic\ncalculations to investigate the properties of BAs heterostructures, such as\nstrain effects on band alignments and carrier mobility, considering BAs as both\na thin film and a substrate for lattice-matched materials. The results show\nthat strain decreases the band gap independent of sign or direction. In\naddition, biaxial tensile strain increases the in-plane electron and hole\nmobilities by more than 60% compared to the unstrained values due to a\nreduction of the electron effective mass and of hole interband scattering.\nMoreover, BAs is shown to be nearly lattice-matched with InGaN and ZnSnN2, two\nimportant optoelectronic semiconductors with tunable band gaps by alloying and\ncation disorder, respectively. The results predict type-II band alignments and\ndetermine the absolute band offsets of these two materials with BAs. The\ncombination of the ultra-high thermal conductivity and intrinsic p-type\ncharacter of BAs, with its high electron and hole mobilities that can be\nfurther increased by tensile strain, as well as the lattice-match and the\ntype-II band alignment with intrinsically n-type InGaN and ZnSnN2 demonstrate\nthe potential of BAs heterostructures for electronic and optoelectronic\ndevices.",
        "positive": "Pi Berry phase and Zeeman splitting of TaP probed by high field\n  magnetotransport measurements: The chiral anomaly-induced negative magnetoresistance and non-trivial Berry\nphase are two fundamental transport properties associated with the topological\nproperties of Weyl fermions. In this work, we report the quantum transport of\nTaP single crystals in magnetic field up to 31T. Through the analyses of our\nmagnetotransport data, we show TaP has the signatures of a Weyl state,\nincluding light effective quasiparticle masses, ultrahigh carrier mobility, as\nwell as negative longitudinal magnetoresistance. Furthermore, we have\ngeneralized the Lifshitz-Kosevich formula for Shubnikov-de Haas (SdH)\noscillations with multi-frequencies, and determined the non-trivial Berry phase\nof Pi for multiple Fermi pockets in TaP through the direct fitting of the\nquantum oscillations. In high fields, we also probed signatures of Zeeman\nsplitting, from which the Land\\'e g-factor is extracted."
    },
    {
        "anchor": "Invisibility's Flicker: Detecting Thermal Cloaks via Transient Effects: Recent research on the development of a thermal cloak has concentrated on\nengineering an inhomogeneous thermal conductivity and homogeneous volumetric\nheat capacity. While the perfect cloak of inhomogeneous $\\kappa$ and $\\rho c_p$\nis known to be exact (no signals scattering or penetrating to the cloak's\ninterior), no such analysis has been considered for this case. Using analytic,\ncomputational, and experimental techniques, we demonstrate that these\napproximate cloaks are detectable. Although they work as perfect cloaks in the\nsteady-state, their transient (time-dependent) response is imperfect and a\ndetectable amount of heat is scattered. This is sufficient to determine the\npresence of a cloak and any heat source it contains, but the material\ncomposition hidden within the cloak is not detectable in practice.",
        "positive": "Ferromagnetism in CaRuO3 thin films by efficient route of tensile\n  epitaxial strain: We show that a ferromagnetic (FM) order in the orthorhombic CaRuO3, which is\na non-magnetic and iso-structural analog of FM system SrRuO3, can be\nestablished and stabilized by the means of tensile epitaxial strain.\nInvestigations on the structural and magnetic property correlations in the\nCaRuO3 films with different degrees of strain reveal that the FM moment\nincreases with increasing the tensile strain. This is an experimental\nverification to the theoretical predictions of scaling of the tensile epitaxial\nstrain and the magnetic order in this system. Our studies further establish\nthat the tensile strain is more efficient than the chemical route to induce the\nFM order in CaRuO3 as the magnetic moment in these strained films is larger\nthan that in chemically modified CaRu0.9Cr0.1O3 films."
    },
    {
        "anchor": "Tuneable Magneto-Resistance by Severe Plastic Deformation: Bulk metallic samples were synthesized from different binary powder mixtures\nconsisting of elemental Cu, Co, and Fe using severe plastic deformation. Small\nparticles of the ferromagnetic phase originate in the conductive Cu phase,\neither by incomplete dissolution or by segregation phenomena during the\ndeformation process. These small particles are known to give rise to granular\ngiant magnetoresistance. Taking advantage of the simple production process, it\nis possible to perform a systematic study on the influence of processing\nparameters and material compositions on the magneto-resistance. Furthermore, it\nis feasible to tune the magnetoresistive behavior as a function of the\nspecimens chemical composition. It was found that specimens of low\nferromagnetic content show an almost isotropic drop in resistance in a magnetic\nfield. With increasing ferromagnetic content, percolating ferromagnetic phases\ncause an anisotropy of the magnetoresistance. By changing the parameters of the\nhigh pressure torsion process, i.e., sample size, deformation temperature, and\nstrain rate, it is possible to tailor the magnitude of giant\nmagneto-resistance. A decrease in room temperature resistivity of approx. 3.5%\nwas found for a bulk specimen containing an approximately equiatomic fraction\nof Co and Cu.",
        "positive": "Reliable postprocessing improvement of van der Waals heterostructures: The successful assembly of heterostructures consisting of several layers of\ndifferent 2D materials in arbitrary order by exploiting van der Waals forces\nhas truly been a game changer in the field of low dimensional physics. For\ninstance, the encapsulation of graphene or MoS2 between atomically flat\nhexagonal boron nitride (hBN) layers with strong affinity and graphitic gates\nthat screen charge impurity disorder provided access to a plethora of\ninteresting physical phenomena by drastically boosting the device quality. The\nencapsulation is accompanied by a self-cleansing effect at the interfaces. The\notherwise predominant charged impurity disorder is minimized and random strain\nfluctuations ultimately constitute the main source of residual disorder.\nDespite these advances, the fabricated heterostructures still vary notably in\ntheir performance. While some achieve record mobilities, others only possess\nmediocre quality. Here, we report a reliable method to improve fully completed\nvan der Waals heterostructure devices with a straightforward post-processing\nsurface treatment based on thermal annealing and contact mode AFM. The impact\nis demonstrated by comparing magnetotransport measurements before and after the\nAFM treatment on one and the same device as well as on a larger set of treated\nand untreated devices to collect device statistics. Both the low temperature\nproperties as well as the room temperature electrical characteristics, as\nrelevant for applications, improve on average substantially. We surmise that\nthe main beneficial effect arises from reducing nanometer scale corrugations at\nthe interfaces, i.e. the detrimental impact of random strain fluctuations."
    },
    {
        "anchor": "Mixed ab initio quantum mechanical and Monte Carlo calculations of\n  secondary emission from SiO2 nanoclusters: A mixed quantum mechanical and Monte Carlo method for calculating Auger\nspectra from nanoclusters is presented. The approach, based on a cluster\nmethod, consists of two steps. Ab initio quantum mechanical calculations are\nfirst performed to obtain accurate energy and probability distributions of the\ngenerated Auger electrons. In a second step, using the calculated line shape as\nelectron source, the Monte Carlo method is used to simulate the effect of\ninelastic losses on the original Auger line shape. The resulting spectrum can\nbe directly compared to 'as-acquired' experimental spectra, thus avoiding\nbackground subtraction or deconvolution procedures. As a case study, the O K-LL\nspectrum from solid SiO2 is considered. Spectra computed before or after the\nelectron has traveled through the solid, i.e., unaffected or affected by\nextrinsic energy losses, are compared to the pertinent experimental spectra\nmeasured within our group. Both transition energies and relative intensities\nare well reproduced.",
        "positive": "Magnetic functionalization and Catalytic behavior of magnetic\n  nanoparticles during laser photochemical graphitization of polyimide: We report laser-assisted photochemical graphitization of polyimides (PI) into\nfunctional magnetic nanocomposites using laser irradiation of PI in the\npresence of magnetite nanoparticles (MNP). PI Kapton sheets covered with MNP\nwere photochemically treated under ambient conditions using a picosecond pulsed\nlaser (1064nm) to obtain an electrically conductive material. Scanning electron\nmicroscopy of the treated material revealed layered magnetic\nnanoparticles/graphite nanocomposite structure (MNP/graphite). Four probe\nconductivity measurements indicated that nanocomposite has an electrical\nconductivity of 1550 S/m. Superconducting quantum interference device (SQUID)\nmagnetometer-based magnetic characterization of the treated material revealed\nan anisotropic ferromagnetic response in the MNP/graphite nanocomposite\ncompared to the isotropic response of MNP. Raman spectroscopy of MNP/graphite\nnanocomposite revealed a four-fold improvement in graphitization, suppression\nin disorder, and decreased nitrogenous impurities compared to the graphitic\nmaterial obtained from laser treatment of just PI sheets. X-ray photoelectron\nspectroscopy, x-ray diffraction, and energy-dispersive x-ray spectroscopy were\nused to delineate the phase transformations of MNP during the formation of\nMNP/graphite nanocomposite. Post-mortem characterization indicates a possible\nphotocatalytic effect of MNP during MNP/graphite nanocomposite formation. Under\nlaser irradiation, MNP transformed from the initial Fe3O4 phase to\n{\\gamma}-Fe2O3 and Fe5C2 phases and acted as nucleation spots to catalyze the\ngraphitization process of PI."
    },
    {
        "anchor": "Giant Rashba-Spin Splitting of Bi(111) Bilayer on Large Band Gap\n  $\u03b2-$In$_2$Se$_3$: Experimentally it is still challenging to epitaxially grow Bi(111) bilayer\n(BL) on conventional semiconductor substrate. Here, we propose a substrate of\n$\\beta-$In$_2$Se$_3$(0001) with van der Waals like cleavage and large band gap\nof 1.2~eV. We have investigated the electronic structure of BL on one\nquintuple-layer (QL) $\\beta-$In$_2$Se$_3$(0001) using density functional theory\ncalculation. It is found that the intermediate hybridization between BL and one\nQL $\\beta-$In$_2$Se$_3$(0001) results in the formation of bands with giant\nRashba spin splitting in the large band gap of the substrate. Furthermore the\nRashba parameter $\\alpha_R$ can be increased significantly by tensile strain of\nsubstrate. Our findings provide a good candidate substrate for BL growth to\nexperimentally realize spin splitting Rashba states with insignificant effect\nof spin degenerate states from the substrate.",
        "positive": "The Behavior of the Intercalant AlCl_4 Anion during the Formation of\n  Graphite Intercalation Compound: An X-ray Absorption Fine Structure Study: This work aims to study the insertion of AlCl_4^- anion in the crystalline\nstructure of oriented pyrolytic graphite (PG) at the point of view of the anion\nitself. The electronic and atomic structures of the anion at different\nintercalation stages are studied. In particular double-edge (bicolor) X-ray\nabsorption spectroscopy at the Al and Cl K-edges is carried out, highlighting a\ncontraction of the anion bonding at the highest intercalation degree obtained\nelectrochemically (stage 3), while the electronic population changes for both\nthe edges upon cycle."
    },
    {
        "anchor": "$\\rm\\bf {^{23}Na}$ NMR spin-lattice relaxation reveals ultrafast $\\rm\\bf\n  Na{^{+}}$ ion dynamics in the solid electrolyte $\\rm\\bf\n  Na{_{3.4}}Sc{_{0.4}}Zr{_{1.6}}(SiO{_{4}}){_{2}}PO{_{4}}$: The realization of green and economically friendly energy storage systems\nneeds materials with outstanding properties. Future batteries based on Na as an\nabundant element take advantage of non-flammable ceramic electrolytes with very\nhigh conductivities. $\\rm Na{_{3}}Zr{_{2}}(SiO{_{4}}){_{2}}PO{_{4}}$-type\nsuperionic conductors are expected to pave the way for inherently safe and\nsustainable all-solid-state batteries. So far, only little information has been\nextracted from spectroscopic measurements to clarify the origins of fast ionic\nhopping on the atomic length scale. Here we combined broad-band conductivity\nspectroscopy and nuclear magnetic resonance (NMR) relaxation to study Na ion\ndynamics from the {\\mu}m to the angstrom length scale. Spin-lattice relaxation\nNMR revealed a very fast Na ion exchange process in $\\rm\nNa{_{3.4}}Sc{_{0.4}}Zr{_{1.6}}(SiO{_{4}}){_{2}}PO{_{4}}$ that is characterized\nby an unprecedentedly high self-diffusion coefficient of $\\rm 9 \\times\n10{^{-12}} m{^{2}}s{^{-1}}$ at $\\rm -10{\\deg}C$. Thus, well below ambient\ntemperature the Na ions have access to elementary diffusion processes with a\nmean residence time $\\rm {\\tau}_{NMR}$ of only $\\rm 2\\; ns$. The underlying\nasymmetric diffusion-induced NMR rate peak and the corresponding conductivity\nisotherms measured in the MHz range reveal correlated ionic motion. Obviously,\nlocal but extremely rapid $\\rm Na{^{+}}$ jumps, involving especially the\ntransition sites in Sc-NZSP, trigger long-range ion transport and push ionic\nconductivity up to $\\rm 2\\; mS\\; cm{^{-1}}$ at room temperature.",
        "positive": "Materials Screening for the Discovery of New Half-Heuslers: Machine\n  Learning versus Ab Initio Methods: Machine learning (ML) is increasingly becoming a helpful tool in the search\nfor novel functional compounds. Here we use classification via random forests\nto predict the stability of half-Heusler (HH) compounds, using only\nexperimentally reported compounds as a training set. Cross-validation yields an\nexcellent agreement between the fraction of compounds classified as stable and\nthe actual fraction of truly stable compounds in the ICSD. The ML model is then\nemployed to screen 71,178 different 1:1:1 compositions, yielding 481 likely\nstable candidates. The predicted stability of HH compounds from three previous\nhigh throughput ab initio studies is critically analyzed from the perspective\nof the alternative ML approach. The incomplete consistency among the three\nseparate ab initio studies and between them and the ML predictions suggests\nthat additional factors beyond those considered by ab initio phase stability\ncalculations might be determinant to the stability of the compounds. Such\nfactors can include configurational entropies and quasiharmonic contributions."
    },
    {
        "anchor": "Giant 2D Skyrmion Topological Hall Effect with Ultrawide Temperature\n  Window and Low-Current Manipulation in 2D Room-Temperature Ferromagnetic\n  Crystals: The discovery and manipulation of topological Hall effect (THE), an abnormal\nmagnetoelectric response mostly related to the Dzyaloshinskii-Moriya\ninteraction (DMI), are promising for next-generation spintronic devices based\non topological spin textures such as magnetic skyrmions. However, most\nskyrmions and THE are stabilized in a narrow temperature window either below or\nover room temperature with high critical current manipulation. It is still\nelusive and challenging to achieve large THE with both wide temperature window\ntill room temperature and low critical current manipulation. Here, by using\ncontrollable, naturally-oxidized, sub-20 and sub-10 nm 2D van der Waals\nroom-temperature ferromagnetic Fe3GaTe2-x crystals, robust 2D THE with\nultrawide temperature window ranging in three orders of magnitude from 2 to 300\nK is reported, combining with giant THE of ~5.4 micro-ohm cm at 10 K and ~0.15\nmicro-ohm cm at 300 K which is 1-3 orders of magnitude larger than that of all\nknown room-temperature 2D skyrmion systems. Moreover, room-temperature\ncurrent-controlled THE is also realized with a low critical current density of\n~6.2*10^5 A cm^-2. First-principles calculations unveil natural\noxidation-induced highly-enhanced 2D interfacial DMI reasonable for robust\ngiant THE. This work paves the way to room-temperature, electrically-controlled\n2D THE-based practical spintronic devices.",
        "positive": "Temperature-dependent structure of an intermetallic ErPd$_2$Si$_2$\n  single crystal: A combined synchrotron and in-house X-ray diffraction study: We have grown intermetallic ErPd$_2$Si$_2$ single crystals employing\nlaser-diodes with the floating-zone method. The temperature-dependent\ncrystallography was determined using synchrotron and in-house X-ray powder\ndiffraction measurements from 20 to 500 K. The diffraction patterns fit well\nwith the tetragonal $I$4/$mmm$ space group (No. 139) with two chemical formulas\nwithin one unit cell. Our synchrotron X-ray powder diffraction study shows that\nthe refined lattice constants are $a$ = 4.10320(2) {\\AA}, $c$ = 9.88393(5)\n{\\AA} at 298 K and $a$ = 4.11737(2) {\\AA}, $c$ = 9.88143(5) {\\AA} at 500 K,\nresulting in the unit-cell volume $V$ = 166.408(1) {\\AA}$^3$ (298 K) and\n167.517(2) {\\AA}$^3$ (500 K). In the whole studied temperature range, we did\nnot find any structural phase transition. Upon cooling, the lattice constants a\nand c are shortened and elongated, respectively."
    },
    {
        "anchor": "Adhesion mechanism of temperature effects on Sn coating on the carbon\n  fiber reinforced polymer substrate by cold spray: Metalization of carbon fiber reinforced polymers (CFRPs) composites by the\nsurface modification method to enhance their electrical conductivity, thermal\nconductivity, electromagnetic shielding, erosion, and radiation protection, has\na significant meaning in the aerospace field. In this study, Sn coating was\nsuccessfully fabricated on the CFRP composite substrate via low-pressure cold\nspray under four gas temperatures (473K, 523K, 573K, and 623K). Their bonding\nmechanism was explored via the surface observation after peel-off adhesion\nstrength, accompanying with surface temperature distribution investigation. The\nresults indicates that we cannot obtain coating at 623 K, the epoxy matrix of\nthe CFRP substrate was gradually eroded during deposition over 523 K.\nMeanwhile, Sn particles melt under 623 K condition. Three kinds of interfaces:\nSn/epoxy, Sn/CF, and Sn/CF/epoxy are revealed as characteristics with respect\nto different gas temperatures to explore the bonding mechanisms.",
        "positive": "Analogy between Jahn-Teller distortion and Rashba spin splitting, and\n  Jahn-Teller counterpart of spin texture: In developing physical theories analogical reasoning has been found to be\nvery powerful, as attested by a number of important historical examples. An\nanalogy between two apparently different phenomena, once established, allows\none to transfer information and bring new concepts from one phenomenon to the\nother. Here we discuss an important analogy between two widely different\nphysical problems, namely, the Jahn-Teller distortion in molecular physics and\nthe Rashba spin splitting in condensed matter physics. By exploring their\nconceptual and mathematical features and by searching for the counterparts\nbetween them, we examine the orbital texture in Jahn-Teller systems, as the\ncounterpart of the spin texture of the Rashba physics, and put forward a\npossible way of experimentally detecting the orbital texture. Finally, we\ndiscuss the analogy by comparing the coexistence of linear Rashba+Dresselhaus\neffects and Jahn-Teller problems for specific symmetries, which allow for\nnon-trivial spin and orbital textures, respectively."
    },
    {
        "anchor": "Seebeck coefficients of half-metallic ferromagnets: In this report the Co2 based Heusler compounds are discussed as potential\nmaterials for spin voltage generation. The compounds were synthesized by\narcmelting and consequent annealing. Band structure calculations were performed\nand revealed the compounds to be half-metallic ferromagnets. Magnetometry was\nperformed on the samples and the Curie temperatures and the magnetic moments\nwere determined. The Seebeck coefficients were measured from low to ambient\ntemperatures for all compounds. For selected compounds high temperature\nmeasurements up to 900 K were performed.",
        "positive": "Temperature effects in the band structure of topological insulators: We study the effects of temperature on the band structure of the Bi$_2$Se$_3$\nfamily of topological insulators using first-principles methods. Increasing\ntemperature drives these materials towards the normal state, with similar\ncontributions from thermal expansion and from electron-phonon coupling. The\nband gap changes with temperature reach $0.3$ eV at $600$ K, of similar size to\nthe changes caused by electron correlation. Our results suggest that\ntemperature-induced topological phase transitions should be observable near\ncritical points of other external parameters."
    },
    {
        "anchor": "Random alloy fluctuations and structural inhomogeneities in $c$-plane\n  In$_{x}$Ga$_{1-x}$N quantum wells: theory of ground and excited electron and\n  hole states: We present a detailed theoretical analysis of the electronic structure of\n$c$-plane InGaN/GaN quantum wells with indium contents varying between 10\\% and\n25\\%. The electronic structure of the quantum wells is treated by means of an\natomistic tight-binding model, accounting for variations in strain and built-in\nfield due to random alloy fluctuations. Our analysis reveals strong\nlocalisation effects in the hole states. These effects are found not only in\nthe ground states, but also the excited states. We conclude that localisation\neffects persist to of order 100~meV into the valence band, for as little as\n10\\% indium in the quantum well, giving rise to a significant density of\nlocalised states. We find, from an examination of the modulus overlap of the\nwave functions, that the hole states can be divided into three regimes of\nlocalisation. Our results also show that localisation effects due to random\nalloy fluctuations are far less pronounced for electron states. However, the\ncombination of electrostatic built-in field, alloy fluctuations and structural\ninhomogeneities, such as well-width fluctuations, can nevertheless lead to\nsignificant localisation effects in the electron states, especially at higher\nindium contents. Overall, our results are indicative of individually localised\nelectron and hole states, consistent with the experimentally proposed\nexplanation of time-dependent photoluminescence results in $c$-plane InGaN/GaN\nQWs.",
        "positive": "Borophosphene: a New Anisotropic Dirac Cone Monolayer with High Fermi\n  Velocity and Unique Feature of Self-doping: Two-dimensional (2D) Dirac cone materials exhibit linear energy dispersion at\nthe Fermi level, where the effective masses of carriers are very close to zero\nand the Fermi velocity is ultrahigh, only 2 ~ 3 orders of magnitude lower than\nthe light velocity. Such the Dirac cone materials have great promise in\nhigh-performance electronic devices. Herein, we have employed the genetic\nalgorithms methods combining with first-principles calculations to propose a\nnew 2D anisotropic Dirac cone material, that is, orthorhombic boron phosphide\n(BP) monolayer named as borophosphene. Molecular dynamics simulation and phonon\ndispersion have been used to evaluate the dynamic and thermal stability of\nborophosphene. Because of the unique arrangements of B-B and P-P dimers, the\nmechanical and electronic properties are highly anisotropic. Of great interest\nis that the Dirac cone of the borophosphene is robust, independent of in-plane\nbiaxial and uniaxial strains, and can also be observed in its one-dimensional\n(1D) zigzag nanoribbons and armchair nanotubes. The Fermi velocities are ~ 105\nm/s, the same order of magnitude with that of graphene. By using a\ntight-binding model, the origin of the Dirac cone of borophosphene is analyzed.\nMoreover, a unique feature of self-doping can be induced by the in-plane\nbiaxial and uniaxial strains of borophosphene and the Curvature effect of\nnanotubes, which is great beneficial to realizing high speed carriers (holes).\nOur results suggest that the borophosphene holds a great promise in\nhigh-performance electronic devices, which could promote the experimental and\ntheoretical studies to further explore the potential applications of other 2D\nDirac cone sheets."
    },
    {
        "anchor": "From hexagonal to rocksalt structure: A computational study of Gallium\n  Selenide under hydrostatic pressure: This article discusses the pressure-induced structural phase transition and\nrelated phonon, electronic and optical properties of hexagonal {\\epsilon}-GaSe\nusing first-principles calculations. The study focuses on optimizing geometric\nand electronic band structures, analyzing the charge density distributions,\natomic vibrations, and phonon spectra, and characterizing the optical\nproperties of GaSe under hydrostatic pressure. The work also includes an\nanalysis of the phase transformation mechanism using the solid-state Nudged\nElastic Band (SS-NEB) method. This research sheds light on the physics of\nstructural phase transitions in layered materials and offers potential for the\ndevelopment of pressure-manipulated electronics or optoelectronics.",
        "positive": "Spin orbit coupling controlled spin pumping effect: Effective spin mixing conductance (ESMC) across the nonmagnetic metal\n(NM)/ferromagnet interface, spin Hall conductivity (SHC) and spin diffusion\nlength (SDL) in the NM layer govern the functionality and performance of pure\nspin current devices with spin pumping technique. We show that all three\nparameters can be tuned significantly by the spin orbit coupling (SOC) strength\nof the NM layer in systems consisting of ferromagnetic insulating Y3Fe5O12\nlayer and metallic Pd1-xPtx layer. Surprisingly, the ESMC is observed to\nincrease significantly with x changing from 0 to 1.0. The SHC in PdPt alloys,\ndominated by the intrinsic term, is enhanced notably with increasing x.\nMeanwhile, the SDL is found to decrease when Pd atoms are replaced by heavier\nPt atoms, validating the SOC induced spin flip scattering model in polyvalent\nPdPt alloys. The capabilities of both spin current generation and spin charge\nconversion are largely heightened via the SOC. These findings highlight the\nmultifold tuning effects of the SOC in developing the new generation of\nspintronic devices."
    },
    {
        "anchor": "Dislocation correlations and the continuum dynamics of the weak line\n  bundle ensemble: Progress toward a first-principles theory of plasticity and work-hardening is\ncurrently impeded by an insufficient picture of dislocation kinetics (the\ndynamic effect of driving forces in a given dislocation theory). This is\nbecause present methods ignore the short-range interaction of dislocations.\nThis work presents a kinetic theory of continuum dislocation dynamics in a\nvector density framework which takes into account the short-range interactions\nby means of suitably defined correlation functions. The weak line bundle\nensemble of dislocations is defined, whereby the treatment of dislocations by a\nvector density is justified. It is then found by direct averaging of the\ndislocation transport equation that additional driving forces arise which are\ndependent on the dislocation correlation. A combination of spatial\ncoarse-graining and statistical averaging of discrete dislocation systems are\nused to evaluate the various classes of tensorial dislocation correlations\nwhich arise in the line bundle kinetic theory. A novel, chiral classification\nof slip system interactions in FCC crystals is used to define proper and\nimproper rotations by which correlation functions corresponding to six\ninteraction classifications can be evaluated. The full set of these six\ndislocation correlations are evaluated from discrete data. Only the\nself-correlations (for densities of like slip system) are found to be highly\nanisotropic. All six classes of correlation functions are found to decay within\n2-4 times the coarse-graining distance. The correlations corresponding to the\ncoplanar interactions are found to be negligible. Implications of the evaluated\ncorrelations for the implementation of vector density continuum dislocation\ndynamics are discussed, especially in terms of an additional correlation\ncomponent of the driving force and a gesture toward a coarse-grained\ndislocation mobility.",
        "positive": "Structural, mechanical, thermodynamic, and electronic properties of\n  thorium hydrides from first principles: We perform first-principles calculations of the structural, electronic,\nmechanical, and thermodynamic properties of thorium hydrides (ThH$_{2}$ and\nTh$_{4}$H$_{15}$) based on the density functional theory with generalized\ngradient approximation. The equilibrium geometries, the total and partial\ndensities of states, charge density, elastic constants, elastic moduli,\nPoisson's ratio, and phonon dispersion curves for these materials are\nsystematically investigated and analyzed in comparison with experiments and\nprevious calculations. These results show that our calculated equilibrium\nstructural parameters are well consistent with experiments. The Th$-$H bonds in\nall thorium hydrides exhibit weak covalent character, but the ionic properties\nfor ThH$_{2}$ and Th$_{4}$H$_{15}$ are different due to their different\nhydrogen concentration. It is found that while in ThH$_{2}$ about 1.5 electrons\ntransfer from each Th atom to H, in Th$_{4}$H$_{15}$ the charge transfer from\neach Th atom is around 2.1 electrons. Our calculated phonon spectrum for the\nstable body-centered tetragonal phase of ThH$_{2}$ accords well with\nexperiments. In addition we show that ThH$_{2}$ in the fluorite phase is\nmechanically and dynamically unstable."
    },
    {
        "anchor": "Dynamic particle packing in freezing colloidal suspensions: In the field of freezing colloidal suspensions, it is important to understand\nthe particle-scale behavior of particle packing. Here, we reveal the dynamics\nof particle packing by identifying the behavior of each single particle in\nsitu. The typical pattern consists of locally ordered clusters and amorphous\ndefects. The microscopic mechanism of pattern formation is ascribed to the\nnon-equilibrium particle-packing process on the particle scale, described with\nthe P\\'eclet number. The macroscopic migration of a particle layer is also\nrevealed by an analytical model involving parameters of freezing speed and\ninitial volume fraction of particles.",
        "positive": "Band gap renormalization and indirect optical absorption in MgSiN$_2$ at\n  finite temperature: We investigate the temperature effect on the electronic band structure and\noptical absorption property of wide-band-gap ternary nitride MgSiN$_2$ using\nfirst-principles calculations. We find that electron-phonon coupling leads to a\nsizable reduction in the indirect gap of MgSiN$_2$, which is indispensable in\nunderstanding the optoelectronic properties of this material. Taking the band\ngap renormalization into account, the band gap of MgSiN$_2$ determined by the\nquasiparticle GW0 calculations shows good agreement with recent experimental\nresult. The predicted phonon-assisted indirect optical absorption spectra show\nthat with increasing temperature the absorption onset undergoes a red-shift.\nOur work provides helpful insights to the nature of the band gap of MgSiN$_2$\nand facilitates its application in ultraviolet optoelectronic devices."
    },
    {
        "anchor": "Efficiently Engineered Room Temperature Single Photons in Silicon\n  Carbide: We report the first observation of stable single photon sources in silicon\ncarbide (SiC). These sources are extremely bright and operate at room\ntemperature demonstrating that SiC is a viable material in which to realize\nvarious quantum information, computation and photonic applications. The maximum\nsingle photon count rate detected is 700k counts/s with an inferred quantum\nefficiency around 70%. The single photon sources are due to intrinsic deep\nlevel defects constituted of carbon antisite-vacancy pairs. These are shown to\nbe formed controllably by electron irradiation. The variability of the temporal\nkinetics of these single defects is investigated in detail.",
        "positive": "Force Distribution and Comminution in Ball Mills: The motion of granular material in a ball mill is investigated using\nmolecular dynamics simulations in two dimensions. In agreement with\nexperimental observations by Rothkegel [1] we find that local stresses - and\nhence the comminution efficiency - are maximal close to the bottom of the\ncontainer. This effect will be explained using analysis of statistics of force\nchains in the material."
    },
    {
        "anchor": "Charge transfer and disorder-induced spin relaxation in La2NiMnO6\n  crystallites: Investigation of the electronic and spin structure in double perovskites is\nrecently attracting significant attention, mainly driven by their unique\nmultifunctional properties and other underlying charge and spin dynamics.\nHerein, using X-ray photoelectron spectroscopy (XPS), we explore the influence\nof variable fractions of Mn3+/Mn4+ cation in different crystallite sizes of\nLa2NiMnO6 that control the various completing exchange interactions of Ni/Mn\ncations responsible for multiple magnetic transitions. The enhanced itinerant\nelectron due to Mn4+ + Ni2+ to Mn3+ + Ni3+ charge transfer emerged as a\nshoulder like characteristics at the low binding energy in the Mn-2P core-level\nspectrum. The various approaches such as difference in saturation\nmagnetization, presence of multiple charge valance, and magnetic entropy\ncalculations confirm the presence of antisites disorder and it varies as a\nfunction of milling. As milling provides excess energy that helps with\nnucleation or cation ordering. Competing magnetic interactions driven by mixed\nvalences and disorder were established across a cluster glassy phase in the\ncrystallites. Electron spin resonance spectroscopy (ESR) was utilized to probe\nthe temperature-driven ferromagnetic-cluster spin-glass transition with\nmodified g-factor ranging from 2.050 to 2.037. The line width of the ESR\nsignals increases across the ferromagnetic to cluster-glass phase transition\ndue to spin freezing. This phase transition is further characterized by\ntemperature-dependent ac-magnetic susceptibility measurements. Argand diagram\nfor the ac-susceptibility of the interacting crystallites suggests a collective\nmagnetization relaxation dynamic in the proximity of spin-glass freezing\ntemperature of La2NiMnO6.",
        "positive": "Anomalous Nernst Effects of [CoSiB/Pt] Multilayer Films: We report a measurement for the anomalous Nernst effects induced by a\ntemperature gradient in [CoSiB/Pt] multilayer films with perpendicular magnetic\nanisotropy. The Nernst voltage shows a characteristic hysteresis which reflects\nthe magnetization of the film as in the case of the anomalous Hall effects.\nWith a local heating geometry, we also measure the dependence of the anomalous\nNernst voltage on the distance d from the heating element. It is roughly\nproportional to 1/d^1.3, which can be conjectured from the expected temperature\ngradient along the sample from the heat equation."
    },
    {
        "anchor": "Binary relations between magnitudes of different dimensions used in\n  material science optimization problems. Pseudo-state equation of Soft\n  Magnetic Composities: Suplementary algoritm for optimizing technological parameters of soft\nmagnetic compozities has been derived on the base of topological structure of\nthe power loss characteristics. In optimization processes of magnitudes obeying\nscaling it happen binary relations of magnitudes having different dimensions.\nFrom mathematical point of view in general case such a procedure is not\npermissible. However, in a case of the system obeying the scaling law it is so.\nIt has been shown that in such systems binary relations of magnitudes of\ndifferent dimensions is correct and has mathematical meaning which is important\nfor practical use of scaling in optimization processes. Derived here structure\nof the set of all power loss characteristics in soft magnetic composite enables\nus to derive a formal pseudo-state equation of SMC. This equation constitutes a\nrealation of the hardening temperature, the compaction pressure and a parameter\ncharacterizing the power loss characteristic. Finally, the pseudo-state\nequation improves the algoritm for designing the best values of technological\nparameters.",
        "positive": "Edge Control of Graphene Domains Grown on Hexagonal Boron Nitride: Edge structure of graphene has a significant influence on its electronic\nproperties. However, control over the edge structure of graphene domains on\ninsulating substrates is still challenging. Here we demonstrate edge control of\ngraphene domains on hexagonal boron nitride (h-BN) by modifying ratio of\nworking-gases. Edge directions were determined with the help of both moir\\'e\npattern and atomic-resolution image obtained via atomic force microscopy\nmeasurement. It is believed that the variation on graphene edges mainly\nattributes to different growth rates of armchair and zigzag edges. This work\ndemonstrated here points out a potential approach to fabricate graphene ribbons\non h-BN."
    },
    {
        "anchor": "GW study of the half-metallic Heusler compounds Co2MnSi and Co2FeSi: Quasiparticle spectra of potentially half-metallic Co2MnSi and Co2FeSi\nHeusler compounds have been calculated within the one-shot GW approximation in\nan all-electron framework without adjustable parameters. For Co2FeSi the\nmany-body corrections are crucial: a pseudogap opens and good agreement of the\nmagnetic moment with experiment is obtained. Otherwise, however, the changes\nwith respect to the density-functional-theory starting point are moderate. For\nboth cases we find that photoemission and x-ray absorption spectra are well\ndescribed by the calculations. By comparison with the GW density of states, we\nconclude that the Kohn-Sham eigenvalue spectrum provides a reasonable\napproximation for the quasiparticle spectrum of the Heusler compounds\nconsidered in this work.",
        "positive": "Nature of glassy magnetic state in magnetocaloric materials Dy5Pd2-xNix\n  (x = 0 and 1) and universal scaling analysis of R5Pd2 (R = Tb, Dy and Er): We report a systematic investigation of the magnetic and magnetocaloric\nproperties of Dy5Pd2 and Dy5PdNi. Our study on these compounds gave evidence\nthat they exhibit complex magnetic behaviour along with the presence of\nglass-like magnetic phase. Furthermore, in these compounds both second order\nand first order phase transitions were present, which were validated through\nArrott plots and Landau parameter analysis. AC susceptibility along with time\ndependent magnetisation study has confirmed the presence of double cluster\nglass-like freezing in both Dy5Pd2 and Dy5PdNi. These compounds show\nsignificant value of isothermal entropy change and relative cooling power and\nthese values increased with Ni substitution. Beside conventional magnetocaloric\neffect, inverse magnetocaloric effect was noted in these compounds, which might\narise due to the presence of complex non-equilibrium magnetic state. Along with\nthese compounds a universal characteristic curve involving two other members of\nR5Pd2 family i.e. Er5Pd2 and Tb5Pd2 was constructed. The master curve\nreaffirmed the presence of both second and first order magnetic phase\ntransition in such compounds which were in analogy to our results of Arrott\nplots and Landau parameter analysis. Additionally, magnetic entropy change\nfollowed the power law and the obtained exponent values indicated the presence\nof mixed magnetic interactions in these compounds."
    },
    {
        "anchor": "Direct Measurement of the Structural Change Associated with Amorphous\n  Solidification using Static Scattering of Coherent Radiation: In this paper we demonstrate that the weak temperature dependence of\nstructure factor of supercooled liquids, a defining feature of the glass\ntransition, is a consequence of the averaging of the scattering intensity\neither due to the use of an incoherent radiation source or explicit angular\naveraging. We show that the speckle scattering at individual wavevectors,\ncalculated from a simulated glass former, exhibits a Debye-Waller factor with a\nsufficiently large temperature dependence to represent a structural order\nparameter capable of distinguishing liquid from glass. We also extract from the\nspeckle intensities a quantity proportional to the variance of the local\nrestraint, i.e. a direct experimental measure of the amplitude of structural\nheterogeneity.",
        "positive": "Diverse Chemistry of Stable Hydronitrogens, and Implications for\n  Planetary and Materials Sciences: Nitrogen hydrides, including ammonia (NH3), hydrazine (N2H4), hydrazoic acid\n(HN3) and etc, are compounds of great fundamental and applied importance. Their\nhigh-pressure behavior is important because of their abundance in giant planets\nand because of the hopes of discoverying high-energy-density materials. Here,\nwe have performed a systematic investi- gation on the structural stability of\nN-H system in a pressure range up to 800 GPa through evolutionary structure\nprediction simulations. Surprisingly, we found that high pressure stabilizes a\nseries of previously unreported compounds with peculiar structural and\nelectronic properties, such as the N4H, N3H, N2H and NH phases composed of\nnitrogen backbones, the N9H4 phase containing two dimensional metallic nitrogen\nplanes and novel N8H, NH2, N3H7, NH4 and NH5 molecular phases. Another surprise\nis that NH3 becomes thermodynamically unstable above ~460 GPa. We found that\nhigh-pressure chemistry is much more diverse that hydrocarbon chemistry at\nnormal conditions, leading to expectations that N-H-O and N-H-O-S systems under\npressure are likely to possess richer chemistry than the known organic\nchemistry. This, in turn, opens a possibility of nitrogen-based life at high\npressure. The predicted phase diagram of the N-H system also provides a\nreference for synthesis of high-energy-density materials."
    },
    {
        "anchor": "Bonding trends within ternary Isocoordinate chalcogenide glasses GeAsSe: A structural study is presented of ab-initio molecular dynamics simulations\nof Ge-As-Se calcogenide glasses performed at the same mean coordination number\nbut differing stoichiometry ranging between Se rich and Se poor glasses.\nStarting configurations are generated via Reverse Monte Carlo (RMC) simulations\nof Extended X-ray Absorption Fine Structure (EXAFS) measurements of\nexperimental samples. Structural analysis is presented illustrating the bonding\ntrends found with changing stoichiometry.",
        "positive": "High-Tc BaTiO3 ferroelectric films with frozen negative pressure states: We report that an energetic plasma process is extremely effective in\nenlarging the unit cell volume and ferroelectric distortion of the\nferroelectric oxides, resulting in a significant increase in its Tc. We\ndemonstrate experimentally that c-axis oriented BaTiO3 films can be deposited\ndirectly on quartz glass and Si substrates using such a process and that the\nmaterial shows an approximately 5% expansion of its unit cell volume and\napproximately 4 times the ferroelectric tetragonal distortion of the bulk\ncrystals. Such a frozen negative pressure results in a Tc value that is\napproximately 580 K higher than that of bulk single crystals, providing a wide\nrange of operating temperatures for the devices. The present results suggest an\napproach to producing ferroelectric oxides with unique properties that might be\nextended to ferromagnetic or superconductor oxides and demonstrate a route to a\nlead-free ferroelectric oxide for capacitive, ferroelectric memory, and\nelectro-optical devices."
    },
    {
        "anchor": "Lattice Discrete Particle Model (LDPM) for pressure-dependent\n  inelasticity in granular rocks: This paper deals with the formulation, calibration, and validation of a\nLattice Discrete Particle Model (LDPM) for the simulation of the\npressure-dependent inelastic response of granular rocks. LDPM is formulated in\nthe framework of discrete mechanics and it simulates the heterogeneous\ndeformation of cemented granular systems by means of discrete\ncompatibility/equilibrium equations defined at the grain scale. A numerical\nstrategy is proposed to generate a realistic microstructure based on the actual\ngrain size distribution of a sandstone and the capabilities of the method are\nillustrated with reference to the particular case of Bleurswiller sandstone,\ni.e. a granular rock that has been extensively studied at the laboratory scale.\nLDPM micromechanical parameters are calibrated based on evidences from triaxial\nexperiments, such as hydrostatic compression, brittle failure at low\nconfinement and plastic behavior at high confinement. Results show that LDPM\nallows exploring the effect of fine-scale heterogeneity on the inelastic\nresponse of rock cores, achieving excellent quantitative performance across a\nwide range of stress conditions. In addition, LDPM simulations demonstrate its\ncapability of capturing different modes of strain localization within a unified\nmechanical framework, which makes this approach applicable for a wide variety\nof geomechanical settings. Such promising performance suggests that LDPM may\nconstitute a viable alternative to existing discrete numerical methods for\ngranular rocks, as well as a versatile tool for the interpretation of their\ncomplex deformation/failure patterns and for the development of continuum\nmodels capturing the effect of micro-scale heterogeneity.",
        "positive": "The crossover from collective motion to periphery diffusion for 2D\n  adatom-islands on Cu(111): The diffusion of two dimensional adatom islands (up to 100 atoms) on Cu(111)\nhas been studied, using the self-learning Kinetic Monte Carlo (SLKMC) method\n[1]. A variety of multiple- and single-atom processes are revealed in the\nsimulations, and the size dependence of the diffusion coefficients and\neffective diffusion barriers are calculated for each. From the tabulated\nfrequencies of events found in the simulation, we show a crossover from\ndiffusion due to the collective motion of the island to a regime in which the\nisland diffuses through periphery-dominated mass transport. This crossover\noccurs for island sizes between 13 and 19 atoms. For islands containing 19 to\n100 atoms the scaling exponent is 1.5, which is in good agreement with previous\nwork. The diffusion of islands containing 2 to 13 atoms can be explained\nprimarily on the basis of a linear increase of the barrier for the collective\nmotion with the size of the island."
    },
    {
        "anchor": "All Inorganic p_n Heterojunction Solar Cells by Solution Combustion\n  Synthesis using n_type FeMnO3 Perovskite Photoactive Layer: This study outlines the synthesis and physicochemical characteristics of a\nsolution-processable iron manganite (FeMnO3) nanoparticles via a chemical\ncombustion method using tartartic acid as a fuel and demonstrates the\nperformance of this material as a n-type photoactive layer in all-oxide solar\ncells. It is shown that the solution combustion synthesis (SCS) method enables\nthe formation of pure crystal phase FeMnO3 with controllable particle size. XRD\npattern and morphology images from TEM confirm the purity of FeMnO3 phase and\nthe relative small crystallite size (~13 nm), firstly reported in the\nliterature. Moreover, to assemble a network of connected FeMnO3 nanoparticles,\n\\b{eta}-alanine was used as a capping agent and dimethylformamide (DMF) as a\npolar aprotic solvent for the colloidal dispersion of FeMnO3 NPs. This\nprocedure yields a ~500 nm thick photoactive layer. The proposed method is\ncrucial to obtain functional solution processed NiO/FeMnO3 heterojunction\ninorganic photovoltaics. The optoelectronic properties of the heterojunction\nwere established. These solar cells demonstrate a high open circuit voltage of\n1.31 V with sufficient fill factor of 54.3% and low short circuit current of\n0.07 mA cm-2 delivering a power conversion efficiency of 0.05% under 100 mW\ncm-2 illumination. This work expands on the burgeoning of environmentally\nfriendly, low-cost, sustainable solar cell material that derive from metal\noxides.",
        "positive": "Bright mid-infrared photoluminescence from high dislocation density\n  epitaxial PbSe films on GaAs: We report on photoluminescence in the 3-7 $\\mu$m mid-wave infrared (MWIR)\nrange from sub-100 nm strained thin films of rocksalt PbSe(001) grown on\nGaAs(001) substrates by molecular beam epitaxy. These bare films, grown\nepitaxially at temperatures below 400 {\\deg}C, luminesce brightly at room\ntemperature and have minority carrier lifetimes as long as 172 ns. The\nrelatively long lifetimes in PbSe thin films are achievable despite threading\ndislocation densities exceeding $10^9$ $cm^{-2}$ arising from island growth on\nthe nearly 8% lattice- and crystal-structure-mismatched GaAs substrate. Using\nquasi-continuous-wave and time-resolved photoluminescence, we show\nShockley-Read-Hall recombination is slow in our high dislocation density PbSe\nfilms at room temperature, a hallmark of defect tolerance. Power-dependent\nphotoluminescence and high injection excess carrier lifetimes at room\ntemperature suggest that degenerate Auger recombination limits the efficiency\nof our films, though the Auger recombination rates are significantly lower than\nequivalent, III-V bulk materials and even a bit slower than expectations for\nbulk PbSe. Consequently, the combined effects of defect tolerance and low Auger\nrecombination rates yield an estimated peak internal quantum efficiency of\nroughly 30% at room temperature, unparalleled in the MWIR for a severely\nlattice-mismatched thin film. We anticipate substantial opportunities for\nimproving performance by optimizing crystal growth as well as understanding\nAuger processes in thin films. These results highlight the unique opportunity\nto harness the unusual chemical bonding in PbSe and related IV-VI\nsemiconductors for heterogeneously integrated mid-infrared light sources\nconstrained by tight thermal budgets in new device designs."
    },
    {
        "anchor": "Electric field effect on short-range polar orders in a relaxor\n  ferroelectric system: Short-range polar orders in the relaxor ferroelectric material\nPbMg$_{1/3}$Nb$_{2/3}$O$_3$-$28\\%$PbTiO$_3$ (PMN-28PT) have been studied using\nneutron diffuse scattering. An external electric field along [110] direction\ncan affect the diffuse scattering in the low temperature\nrhombohedral/monoclinic phase. Diffuse scattering intensities associated with\n[110] short-range polarizations are partially suppressed, while those arising\nfrom [1$\\bar{1}$0] polarizations are enhanced. On the other hand, short-range\npolar orders along other equivalent $\\langle110\\rangle$ directions, i.e.\n[101],[10$\\bar{1}$], [011], and [01$\\bar{1}$] directions, are virtually\nunaffected by the field. Our results, combined with previous work, strongly\nsuggest that most part of short-range polar orders in PMN-$x$PT relaxor systems\nare robust in the low temperature phase, where they couple strongly to\nferroelectric polarizations of the surrounding ferroelectric domains, and would\nonly respond to an external field indirectly through ferroelectric domain\nrotation.",
        "positive": "Layer Construction of Three-Dimensional Z2 Monopole Charge Nodal Line\n  Semimetals and prediction of the abundant candidate materials: The interplay between symmetry and topology led to the concept of\nsymmetry-protected topological states, including all non-interacting and weakly\ninteracting topological quantum states. Among them, recently proposed nodal\nline semimetal states with space-time inversion ($\\mathcal{PT}$) symmetry which\nare classified by the Stiefel-Whitney characteristic class associated with real\nvector bundles and can carry a nontrivial $\\mathbb{Z}_2$ monopole charge have\nattracted widespread attention. However, we know less about such 3D\n$\\mathbb{Z}_2$ nodal line semimetals and do not know how to construct them. In\nthis work, we first extend the layer construction previously used to construct\ntopological insulating states to topological semimetallic systems. We construct\n3D $\\mathbb{Z}_2$ nodal line semimetals by stacking of 2D\n$\\mathcal{PT}$-symmetric Dirac semimetals via nonsymmorphic symmetries. Based\non our construction scheme, effective model and combined with first-principles\ncalculations, we predict two types of candidate electronic materials for\n$\\mathbb{Z}_2$ nodal line semimetals, namely 14 Si and Ge structures and 108\ntransition metal dichalcogenides $MX_2$ ($M$=Cr, Mo, W, $X$=S, Se, Te). Our\ntheoretical construction scheme can be directly applied to metamaterials and\ncircuit systems. Our work not only greatly enriches the candidate materials and\ndeepens the understanding of $\\mathbb{Z}_2$ nodal line semimetal states but\nalso significantly extends the application scope of layer construction."
    },
    {
        "anchor": "Spin accumulation in ferromagnets: Using a density matrix formulation for the effective action, we obtain a set\nof macroscopic equations that describe spin accumulation in a non-homogeneous\nferromagnet. We give a new expression for the spin current which extends\nprevious work by taking into account the symmetry of the ferromagnetic state\nthrough a careful treatment of the exchange term between the conduction\nelectrons and the magnetization, i.e, d-electrons. We consider a simple\napplication which has been discussed previously and show that in this case spin\naccumulation is an interface effect confirming earlier results arrived at by\ndifferent methods.",
        "positive": "High-pressure x-ray diffraction and ab initio study of Ni2Mo3N, Pd2Mo3N,\n  Pt2Mo3N, Co3Mo3N, and Fe3Mo3N: Two families of ultra-incompressible\n  bimetallic interstitial nitrides: We have studied by means of high-pressure x-ray diffraction the structural\nstability of Ni2Mo3N, Co3Mo3N, and Fe3Mo3N. We also report ab initio computing\nmodeling of the high-pressure properties of these compounds, Pd2Mo3N, and\nPt2Mo3N. We have found that the nitrides remain stable in the ambient-pressure\ncubic structure at least up to 50 GPa and determined their equation of state.\nAll of them have a bulk modulus larger than 300 GPa. Single-crystal elastic\nconstants have been calculated in order to quantify the stiffness of the\ninvestigated nitrides. We found that they should have a Vickers hardness\nsimilar to that of cubic spinel nitrides like gamma-Si3N4"
    },
    {
        "anchor": "Manipulating Kondo Temperature via Single Molecule Switching: Two conformations of isolated single TBrPP-Co molecules on a Cu(111) surface\nare switched by applying +2.2 V voltage pulses from a scanning tunneling\nmicroscope tip at 4.6 K. The TBrPP-Co has a spin-active cobalt atom caged at\nits center and the interaction between the spin of this cobalt atom and free\nelectrons from the Cu(111) substrate can cause a Kondo resonance. Tunneling\nspectroscopy data reveal that switching from the saddle to a planar molecular\nconformation enhances spin-electron coupling, which increases the associated\nKondo temperature from 130 K to 170 K. This result demonstrates that the Kondo\ntemperature can be manipulated just by changing molecular conformation without\naltering chemical composition of the molecule.",
        "positive": "Controllable modification of the anisotropy energy in Laves phase YFe2\n  by Ar+ ion implantation: Implanted 3.25 keV Ar+ ions have been used to modify the in-plane bulk\nanisotropy in thin films of epitaxially grown Laves phase YFe2. The magneto\noptical Kerr effect, vibrating sample magnetometry and computational modeling\nhave been used to show that the dominant source of anisotropy changes from\nmagnetoelastic in as-grown samples to magnetocrystalline in ion implanted\nsamples. This change occurs at a critical fluence of order 1017 Ar+ ions cm-2.\nThe change in source of the anisotropy is attributed to a relaxation of the\nstrain inherent in the epitaxially grown thin-films. Atomic force microscopy\nshows that the samples' topography remains unchanged after ion implantation.\nThe ability to control the dominant source of magnetic anisotropy without\naffecting the sample surface could have important consequences in the\nfabrication of patterned media for high use in density magnetic data storage\ndevices."
    },
    {
        "anchor": "Dynamics of Photo-excited Spins in InSb Based Quantum Wells: We report time resolved measurements of spin relaxation in doped and undoped\nInSb quantum wells using degenerate and two-color magneto-optical Kerr effect\ntechniques. We observed that the photo-excited spin dynamics are strongly\ninfluenced by laser excitation fluence and the doping profile of the samples.\nIn the low fluence regime, an oscillatory pattern was observed at low\ntemperatures ($\\leq$ 77 K) in the samples with an asymmetric doping profile\nwhich might be attributed to the quasi-collision-free spin relaxation regime.\nOur measurements also suggest the influence of the barrier materials\n(Al$_{x}$In$_{1-x}$Sb) on the spin relaxation in these material systems.",
        "positive": "J-aggregates of thiacyanine dye organized in LB films: effect of\n  irradiation of light: In the present communication we report the preparation and characterizations\nof Langmuir and Langmuir-Blodgett films of a thiacyanine dye-dioctadecyl\nthiacyanine perchlorate (NK) mixed with Octadecyl trimethyl ammonium bromide\n(OTAB). The relationship between the molar ratio of OTAB and NK and the\norientation of molecules at the air-water interface was investigated using\nsurface pressure - area per molecule ({\\pi}-A) isotherm. UV-Vis absorption and\nfluorescence spectroscopic investigations reveal that prominent J-aggregation\nof NK molecule was observed in the LB films lifted at higher surface pressure.\nThis J-aggregation can be controlled by diluting the NK molecules with OTAB. It\nwas observed that the J-aggregates of NK decayed to monomer and H-aggregates\nwhen the NK-LB film was exposed to a monochromatic light of wavelength 460 nm\n(Lambda max of J - aggregates)."
    },
    {
        "anchor": "Thermal Stability and Fracture Patterns of a Recently Synthesized\n  Monolayer Fullerene Network: A Reactive Molecular Dynamics Study: New monolayer 2D carbon structures, namely qHPC60 and qTPC60, were recently\nsynthesized by covalently bonding C60 polymers. Here, we carried out Reactive\n(ReaxFF) molecular dynamics simulations to study the thermodynamic stability\nand fracture patterns of qHPC60 and qTPC60. Our results showed that these\nstructures present similar thermal stability, with sublimation points of 3898K\nand 3965K, respectively. qHPC60 and qTPC60 undergo an abrupt structural\ntransition becoming totally fractured after a critical strain threshold. The\ncrack propagation is linear (non-linear) for qHPC60 (qTPC60). The estimated\nelastic modulus for qHPC60 and qTPC60 are 175.9 GPa and 100.7 GPa,\nrespectively.",
        "positive": "Influence of surface centers on the effective surface recombination rate\n  and the parameters of silicon solar cells: The results of our researches of the influence of exponentially distributed\nsurface centers on the effective surface recombination rate and the parameters\nof silicon solar cells (SCs) are reported. In our calculations, we assumed the\nacceptor and donor surface states to lie in the upper and lower, respectively,\nparts of the bandgap. The model also supposed a discrete surface level to exist\nin the middle of the energy gap. In the case where the integrated concentration\nof continuously distributed centers is comparable with that of deep surface\nlevels, those centers can affect the SC parameters only due to the\nrecombination. If the concentration of continuously distributed centers is\ncomparable or higher than the concentration characterizing a charge built-in\ninto the insulator, those centers directly affect the surface band bending and\nthe photo-induced electromotive force. With the help of a computer simulation,\nthe conditions for the rate of surface recombination through continuously\ndistributed surface centers to exceed that through the deep discrete level are\ndetermined. A decrease of the open-circuit voltage in inverted silicon SCs\nassociated with the recombination through continuously distributed centers is\ncalculated. The obtained theoretical results are compared with the experimental\ndata."
    },
    {
        "anchor": "Tunable spin textures in polar antiferromagnetic hybrid organic\n  inorganic perovskites by electric and magnetic fields: The hybrid organic inorganic perovskites (HOIPs) have attracted much\nattention for their potential applications as novel optoelectronic devices.\nRemarkably, the Rashba band splitting, together with specific spin orientations\nin k space (i.e., spin texture), has been found to be relevant for the\noptoelectronic performances. In this work, by using first principles\ncalculations and symmetry analyses, we study the electric polarization,\nmagnetism, and spin texture properties of the antiferromagnetic (AFM) HOIP\nferroelectric TMCM_MnCl3 (TMCM = (CH3)3NCH2Cl, trimethylchloromethyl ammonium).\nThis recently synthesized compound is a prototype of order disorder and\ndisplacement-type ferroelectric with a large piezoelectric response, high\nferroelectric transition temperature, and excellent photoluminescence\nproperties [You et al., Science 357, 306 (2017)]. The most interesting result\nis that the inversion symmetry breaking coupled to the spin orbit coupling\ngives rise to a Rashba-like band splitting and a related robust persistent spin\ntexture (PST) and/or typical spiral spin texture, which can be manipulated by\ntuning the ferroelectric or, surprisingly, also by the AFM magnetic order\nparameter. The tunability of spin texture upon switching of AFM order parameter\nis largely unexplored and our findings not only provide a platform to\nunderstand the physics of AFM spin texture but also support the AFM HOIP\nferroelectrics as a promising class of optoelectronic materials.",
        "positive": "Understanding correlation effects for ion conduction in polymer\n  electrolytes: Polymer electrolytes typically exhibit diminished ionic conductivity due to\nthe presence of correlation effects between the cations and anions.\nMicroscopically, transient ionic aggregates, e.g. {\\it ion-pairs}, {\\it\nion-triplets} or higher order ionic clusters, engender ionic correlations.\nEmploying {\\it all-atom} simulation of a model polymer electrolyte comprising\nof poly(ethylene oxide) and lithium iodide, the ionic correlations are explored\nthrough construction of elementary functions between pairs of the ionic species\nthat qualitatively explains the spatio-temporal nature of these correlations.\nFurthermore, commencing from the exact Einstein-like equation describing the\ncollective diffusivity of the ions in terms of the average diffusivity of the\nions (i.e. the self terms) and the correlations from distinct pairs of ions,\nseveral phenomenological parameters are introduced to keep track of the\nsimplification procedure that finally boils down to the recently proposed\nphenomenological model by Stolwijk-Obeidi (SO) [N. A. Stolwijk and S. Obeidi,\nPhys. Rev. Lett. 93, 125901, 2004]. The approximation parameters, which can be\nretrieved from simulations, point to the necessity of additional information in\norder to fully describe the correlation effects apart from merely the fraction\nof ion-pairs which apparently accounts for the correlations originating from\nonly the nearest neighbor structural correlations. These parameters are close\nto but not exactly unity as assumed in the SO model. Finally, as an application\nof the extended SO model one is able to estimate the dynamics of the free and\nnon-free ions as well as their fractions from the knowledge of the single\nparticle diffusivities and the collective diffusivity of the ions."
    },
    {
        "anchor": "Poisson ratio and excess low-frequency vibrational states in glasses: In glass, starting from a dependence of the Angell's fragility on the Poisson\nratio [V. N. Novikov and A. P. Sokolov, Nature 431, 961 (2004)], and a\ndependence of the Poisson ratio on the atomic packing density [G. N. Greaves et\nal., Nat. Mater. 10, 823 (2011)], we propose that the heterogeneities are\npredominantly density fluctuations in strong glasses (lower Poisson ratio) and\nshear elasticity fluctuations in fragile glasses (higher Poisson ratio).\nBecause the excess of low-frequency vibration modes in comparison with the\nDebye regime (boson peak) is strongly connected to these fluctuations, we\npropose that they are breathing-like (with change of volume) in strong glasses\nand shear-like (without change of volume) in fragile glasses. As a\nverification, it is confirmed that the excess modes in the strong silica glass\nare predominantly breathing-like. Moreover, it is shown that the excess\nbreathing-like modes in a strong polymeric glass are replaced by shear-like\nmodes under hydrostatic pressure as the glass becomes more compact.",
        "positive": "Temperature dependent photon emission spectra of free excitons in phonon\n  field of GaN: Temperature-dependent radiative recombination of free excitons involving one\nor two LO phonons in GaN is investigated in detail. It is found that both\nphonon sidebands possess asymmetric lineshape and their energy spacings from\nthe zero phonon line strongly deviate from the characteristic energy of LO\nphonons as the temperature increases. Furthermore, the deviation rates of one\nand two phonon sidebands are significantly different. Segall-Mahan theory,\ntaking the exciton-photon and exciton-phonon interactions into account, is\nemployed to calculate the sidebands of one or two LO phonons for free excitons\nin a wide temperature range. Excellent agreement between theory and experiment\nis achieved by using only one adjustable parameter (effective mass of free\nexcitons). The obtained effective mass indicates that the free excitons in GaN\nare likely much lighter than estimated by available theoretical studies."
    },
    {
        "anchor": "Anharmonic effects in the optical and acoustic bending modes of graphene: The out-of-plane fluctuations of carbon atoms in a graphene sheet have been\nstudied by means of classical molecular dynamic simulations with an empirical\nforce-field as a function of temperature. The Fourier analysis of the\nout-of-plane fluctuations often applied to characterize the acoustic bending\nmode of graphene is extended to the optical branch, whose polarization vector\nis perpendicular to the graphene layer. This observable is inaccessible in a\ncontinuous elastic model of graphene but it is readily obtained by the\natomistic treatment. Our results suggest that the long-wavelength limit of the\nacoustic out-of-plane fluctuations of a free layer without stress is\nqualitatively similar to that predicted by a harmonic model under a tensile\nstress. This conclusion is a consequence of the anharmonicity of both in-plane\nand out-of-plane vibrational modes of the lattice. The most striking anharmonic\neffect is the presence of a linear term, $\\omega_{A}=v_{A}k$, in the dispersion\nrelation of the acoustic bending band of graphene at long wavelengths\n($k\\rightarrow0$). This term implies a strong reduction of the amplitude of\nout-of-plane oscillations in comparison to a flexural mode with a\n$k^{2}$-dependence in the long-wavelength limit. Our simulations show an\nincrease of the sound velocity associated to the bending mode, as well as an\nincrease of its bending constant, $\\kappa,$ as the temperature increases.\nMoreover, the frequency of the optical bending mode, $\\omega_{O}(\\Gamma)$, also\nincreases with the temperature. Our results are in agreement with recent\nanalytical studies of the bending modes of graphene using either perturbation\ntheory or an adiabatic approximation in the framework of continuous layer\nmodels.",
        "positive": "An In Situ Surface-Enhanced Infrared Absorption Spectroscopy Study of\n  Electrochemical CO2 Reduction: Selectivity Dependence on Surface C-Bound and\n  O-Bound Reaction Intermediates: The CO_{2} electro-reduction reaction (CORR) is a promising avenue to convert\ngreenhouse gases into high-value fuels and chemicals, in addition to being an\nattractive method for storing intermittent renewable energy. Although\npolycrystalline Cu surfaces have long known to be unique in their capabilities\nof catalyzing the conversion of CO_{2} to higher-order C1 and C2 fuels, such as\nhydrocarbons (CH_{4}, C_{2}H_{4} etc.) and alcohols (CH_{3}OH, C_{2}H_{5}OH),\nproduct selectivity remains a challenge. In this study, we select three metal\ncatalysts (Pt, Au, Cu) and apply in situ surface enhanced infrared absorption\nspectroscopy (SEIRAS) and ambient-pressure X-ray photoelectron spectroscopy\n(APXPS), coupled to density-functional theory (DFT) calculations, to get\ninsight into the reaction pathway for the CORR. We present a comprehensive\nreaction mechanism for the CORR, and show that the preferential reaction\npathway can be rationalized in terms of metal-carbon (M-C) and metal-oxygen\n(M-O) affinity. We show that the final products are determined by the\nconfiguration of the initial intermediates, C-bound and O-bound, which can be\nobtained from CO_{2} and (H)CO_{3}, respectively. C1 hydrocarbons are produced\nvia OCH_{3, ad} intermediates obtained from O-bound CO_{3, ad} and require a\ncatalyst with relatively high affinity for O-bound intermediates. Additionally,\nC2 hydrocarbon formation is suggested to result from the C-C coupling between\nC-bound CO_{ad} and (H)CO_{ad}, which requires an optimal affinity for the\nC-bound species, so that (H)CO_{ad} can be further reduced without poisoning\nthe catalyst surface. Our findings pave the way towards a design strategy for\nCORR catalysts with improved selectivity, based on this\nexperimental/theoretical reaction mechanisms that have been identified."
    },
    {
        "anchor": "Moment-functional based spectral density-functional theory: We describe a density-functional method which aims at computing the ground\nstate electron density and the spectral function at the same time. One basic\ningredient of our method is the construction of the spectral function from the\nfirst four spectral moment matrices. The second basic ingredient is the\nconstruction of the spectral moment matrices from density functionals. We call\nour method moment-functional based spectral density-functional theory\n(MFbSDFT), because it is based on density-functionals for the spectral moments\nand because it allows us to compute the spectral function. If it is implemented\nin second variation our method consumes only a fraction more computer time than\na standard DFT calculation with the PBE functional. We show that MFbSDFT\ncaptures correlation effects such as the valence-band satellite in Ni and the\nformation of lower and upper Hubbard bands in SrVO$_3$. For the purpose of\nconstructing the spectral function from the first four $N\\times N$ spectral\nmoment matrices we describe an efficient algorithm based on the diagonalization\nof one hermitean $2N\\times 2N$ matrix.",
        "positive": "Ultra-Slow Dynamic Annealing of Neutron-induced Defects in n-type\n  Silicon: Role of Charge Carriers: Neutron bombardments with equivalent fluence (1$\\times$10$^{10}$ cm$^{-2}$)\nand different fluxes ($2.5\\times$10$^5$ cm$^{-2}$s$^{-1}$ to $1\\times$10$^7$\ncm$^{-2}$s$^{-1}$) have been performed on three kinds of bipolar devices with\nn-type silicon as active regions. The measured increase of base currents and\ninput bias currents are found to decrease with increasing neutron flux,\nimplying that the strength of the dynamic annealing of divacancy defects in\nn-type silicon follows a positive flux dependence. Such a flux dependence is\nthe same as that observed in ions implantation using protons, but the evident\nflux sensitivity in our experiment is 4 orders of magnitude lower than that of\nproton bombardment, despite the similarity in the masses and energies of the\ntwo particles. The huge discrepancy of flux range is attributed to the presence\nof vast charge carriers in proton bombardments, which strongly accelerate the\ndynamic annealing of defects by enhancing the diffusion velocity of Si\ninterstitials and dissociation rate of defect clusters. Our work would\ncontribute to the understanding of the defect annealing processes in silicon."
    },
    {
        "anchor": "Crossover Between Weak Antilocalization and Weak Localization and\n  Electron-Electron Interaction in Few-Layer WTe$_2$: We report electron transport studies in an encapsulated few-layer WTe$_2$ at\nlow temperatures and high magnetic fields. The magnetoconductance reveals a\ntemperature-induced crossover between weak antilocalization (WAL) and weak\nlocalization (WL) in quantum diffusive regime. We show that the crossover\nclearly manifests coexistence and competition among several characteristic\nlengths, including the dephasing length, the spin-flip length, and the mean\nfree path. In addition, low temperature conductance increases logarithmically\nwith the increase of temperature indicating an interplay of electron-electron\ninteraction (EEI) and spin-orbit coupling (SOC). We demonstrate the existences\nand quantify the strengths of EEI and SOC which are considered to be\nresponsible for gap opening in the quantum spin hall state in WTe2 at the\nmonolayer limit.",
        "positive": "Effect of Self-Lubricating Carbon Materials on the Tribological\n  Performance of Ultra-High-Molecular-Weight Polyethylene: Ultra-high-molecular-weight polyethylene (UHMWPE) has been the gold standard\nfor total knee replacements. Due to the knee's natural movements, UHMWPE wear\ndebris production is inevitable. The debris, at the micron and submicron level,\nresults in the joint's mechanical instability, reduced mobility, increased\npain, and implant loosening. Wear debris production has been linked to UHMWPE\nmechanical properties; therefore, improvements to increase the UHMWPE\nmechanical properties will impact the component's longevity. Here, TiC coating\nand multiwalled carbon nanotubes (MWCNTs) were used to decrease the UHMWPE\nwear. After 400,000 cycles, the UHMWPE-MWCNT diminishes the mass loss compared\nto UHMWPE, and the combination with TiC decreased the material loss by ~ 43.7 %\ncompared to the reference pair. Cold-flow and burnishing were the predominant\nwear modes."
    },
    {
        "anchor": "Charge-induced spin polarization in non-magnetic organic molecule\n  Alq$_{3}$: Electrical injection in organic semiconductors is a key prerequisite for the\nrealization of organic spintronics. Using density-functional theory\ncalculations we report the effect of electron transfer into the organic\nmolecule Alq$_3$. Our first-principles simulations show that electron injection\nspontaneously spin-polarizes non-magnetic Alq$_3$ with a magnetic moment\nlinearly increasing with induced charge. An asymmetry of the Al--N bond lengths\nleads to an asymmetric distribution of injected charge over the molecule. The\nspin-polarization arises from a filling of dominantly the nitrogen $p_z$\norbitals in the molecule's LUMO together with ferromagnetic coupling of the\nspins on the quinoline rings.",
        "positive": "High field transport in graphene: In this work, high field carrier transport in two dimensional (2D) graphene\nis investigated. Analytical models are applied to estimate the saturation\ncurrents in graphene, based on the high scattering rate of optical phonon\nemission. Non-equilibrium (hot) phonon effect was studied by Monte Carlo (MC)\nsimulations. MC simulation confirms that hot phonon effects play a dominant\nrole in current saturation in graphene. Current degradation due to elastic\nscattering events is much smaller compared to the hot phonon effect. Transient\nphenomenon as such as velocity overshoot was also studied using MC simulation.\nThe simulation results shows promising potential for graphene to be used in\nhigh speed electronic devices by shrinking the channel length below 100nm if\nelectrostatic control can be exercised in the absence of a band gap."
    },
    {
        "anchor": "Grapheayne: a class of low-energy carbon allotropes with diverse\n  optoelectronic and topological properties: A series of carbon allotropes with novel optoelectronic and rich topological\nproperties is predicted by systematic first-principles calculations. These\nfascinating carbon allotropes can be derived by inserting acetylenic linkages\n(-C$\\equiv$C-) into graphite, hence they are termed as grapheaynes. Grapheaynes\npossess two different space groups, $P$2/$m$ or $C$2/$m$, and contain\nsimultaneously the $sp$, $sp^2$, and $sp^3$ chemical bonds. They have formation\nenergies lower than the already experimentally synthesized graphdiyne and other\ntheoretically predicted carbon allotropes with acetylenic linkages.\nParticularly, when the width $n$ of grapheayne-$n$ exceeds 15, its cohesive\nenergy is lower than that of diamond, and approaches that of graphite with\nincreasing $n$. Remarkably, we find that some grapheaynes behave as\nsemiconductors with direct narrow band gaps and own the highest absorption\ncoefficients among all known semiconducting carbon allotropes, while some\nothers are topological semimetals with nodal lines. Especially, some\ngrapheaynes can be engineered with tunable direct band gaps in the range of\n1.07-1.87 eV and have ideal properties for photovoltaic applications. Our work\nnot only uncovers the unique atomic arrangement and prominent properties of the\ngrapheayne family, but also offers a treasury that provides promising materials\nfor catalyst, energy storage, molecular sieves, solar cell, and electronic\ndevices.",
        "positive": "A window into NV center kinetics via repeated annealing and spatial\n  tracking of thousands of individual NV centers: Knowledge of the nitrogen-vacancy center formation kinetics in diamond is\ncritical to engineering sensors and quantum information devices based on this\ndefect. Here we utilize the longitudinal tracking of single NV centers to\nelucidate NV defect kinetics during high-temperature annealing from 800-1100\n$^\\circ$C in high-purity chemical-vapor-deposition diamond. We observe three\nphenomena which can coexist: NV formation, NV quenching, and NV orientation\nchanges. Of relevance to NV-based applications, a 6 to 24-fold enhancement in\nthe NV density, in the absence of sample irradiation, is observed by annealing\nat 980 $^\\circ$C, and NV orientation changes are observed at 1050 $^\\circ$C.\nWith respect to the fundamental understanding of defect kinetics in ultra-pure\ndiamond, our results indicate a significant vacancy source can be activated for\nNV creation between 950-980 $^\\circ$C and suggests that native hydrogen from\nNVH$_y$ complexes plays a dominant role in NV quenching, in agreement with\nrecent {\\it ab initio} calculations. Finally, the direct observation of\norientation changes allows us to estimate an NV diffusion barrier of 5.1~eV."
    },
    {
        "anchor": "Orientation Sensitive Nonlinear Growth of Graphene: A\n  Geometry-determined Epitaxial Growth Mechanism: Although the corresponding carbon-metal interactions can be very different, a\nsimilar nonlinear growth behavior of graphene has been observed for different\nmetal substrates. To understand this interesting experimental observation, a\nmultiscale $\\lq\\lq$standing-on-the-front\" kinetic Monte Carlo study is\nperformed. An extraordinary robust geometry effect is identified, which solely\ndetermines the growth kinetics and makes the details of carbon-metal\ninteraction not relevant at all. Based on such a geometry-determined mechanism,\nepitaxial growth behavior of graphene can be easily predicted in many cases. As\nan example, an orientation-sensitive growth kinetics of graphene on Ir(111)\nsurface has been studied. Our results demonstrate that lattice mismatch pattern\nat the atomic level plays an important role for macroscopic epitaxial growth.",
        "positive": "Extension of the LDA-1/2 method to the material class of bismuth\n  containing III-V semiconductors: The LDA-1/2 method is employed in density functional theory calculations for\nthe electronic structure of III-V dilute bismide systems. For the\nrepresentative example of Ga(SbBi) with Bi concentrations below $10 \\%$, it is\nshown that this method works very efficiently, especially due to its reasonably\nlow demand on computer memory. The resulting bandstructure and wavefunctions\nare used to compute the interaction matrix elements that serve as input to\nmicroscopic calculations of the optical properties and intrinsic losses\nrelevant for optoelectronic applications of dilute bismides."
    },
    {
        "anchor": "Tunable Low-Loss Hyperbolic Plasmon Polaritons in a T$_{d}\\,$-WTe$_2$\n  Single Layer: Natural hyperbolic two-dimensional systems are a fascinating class of\nmaterials that could open alternative pathways to the manipulation of plasmon\npropagation and light-matter interactions. Here, we present a comprehensive\nstudy of the optical response in T$_d\\,$-WTe$_2$ by means of density-functional\nand many-body perturbation theories. We show how monolayer WTe$_2$ with\nin-plane anisotropy sustains hyperbolic plasmon polaritons, which can be tuned\nvia chemical doping and strain. The latter is able to extend the hyperbolic\nregime toward the near infrared with low losses. Moreover, with a moderate\nstrain, WTe$_2$ can even be switched between elliptic and hyperbolic regimes.\nIn addition, plasmons in WTe$_2$ are characterized by low losses owing to\nelectron-phonon scattering, which is responsible for the temperature dependence\nof the plasmon line width. Interestingly, the temperature can also be utilized\nto tune the in-plane anisotropy of the WTe$_2$ optical response.",
        "positive": "Self-assembled structure of dendronized CdS nanoparticles: Self-assembled dendronized CdS nanoparticles have been attracting\nconsiderable attention because of their photoluminescence properties depending\non annealing treatments. In this study, their annealing-induced self-assembled\nstructure was investigated via scanning transmission electron microscopy\n(STEM); thin foil specimens of self-assembled dendronized CdS nanoparticles\nwere prepared by ultramicrotomy and the STEM images revealed their ordered\nstructure and the effect of the annealing treatment. In addition, a structural\norder belonging to the P213 space group was identified via an autocorrelation\nanalysis. The results indicated that this structural order could be achieved\nonly over a few tens of nanometers."
    },
    {
        "anchor": "Magnetic excitations in an ionic spin-chain system with a non-magnetic\n  ferroelectric instability: Cross-correlation between magnetism and dielectric is expected to offer novel\nemergent phenomena. Here, magnetic excitations in the organic donor-acceptor\nspin-chain system, TTF-BA, with a ferroelectric ground state is investigated by\n$^1$H-NMR spectroscopy. A nonmagnetic transition with a ferroelectric order is\nmarked by sharp drops in NMR shift and nuclear spin relaxation rate $T_1^{-1}$\nat 53 K. Remarkably, the analyses of the NMR shift and $T_1^{-1}$ dictate that\nthe paramagnetic spin susceptibility in TTF-BA is substantially suppressed from\nthat expected for the 1D Heisenberg spins. We propose that the spin-lattice\ncoupling and the ferroelectric instability cooperate to promote precursory\npolar singlet formation in the ionic spin system with a nonmagnetic\nferroelectric instability.",
        "positive": "Room-temperature formation of Pt$_3$Si/Pt$_2$Si films on poly-Si\n  substrates: We propose a way of formation of thin bilayer Pt$_3$Si/Pt$_2$Si films at room\ntemperature on poly-Si substrates by Pt magnetron sputtering and wet etching,\nobtain such film, investigate its structure and phase composition and estimate\nthe thickness of its layers. We verify by direct x-ray\nphotoelectron-spectroscopic measurements our previous observation of the\nPt$_2$Si layer formaton between Pt and poly-Si films as a result of Pt\nmagnetron sputtering at room temperature. This layer likely appears due to high\nenough temperature of Pt ions in the magnetron plasma sufficient for chemical\nreaction of the silicide film formation on the Si surface. The Pt$_3$Si layer\nlikely forms from the Pt--Pt$_3$Si layer (Pt$_{95}$Si$_5$), which arises under\nPt film during the magnetron sputtering, as a result of Pt removal by wet\netching."
    },
    {
        "anchor": "Electromigration-guided composition patterns in thin alloy films: a\n  computational study: Via computation of a continuum dynamical model of the diffusion and\nelectromigration, this paper demonstrates the feasibility of guiding the\nformation of the stripe composition patterns in the thin surface layers of the\ncrystal alloy films. By employing the systematic parametric computational\nanalysis it is revealed how such properties of the pattern as the aerial number\ndensity of the stripes and the stripe in-plane orientation are influenced by\nthe major physical factors that are not limited to the electric field strength\nand its direction angle in the plane, but also include a number of parameters\nthat originate in the anisotropy of diffusion in the particular\ncrystallographically-oriented surface layer. By following the insights from\nthis analysis the real patterns hopefully can be created in a dedicated\nexperiment.",
        "positive": "Spin-filtering efficiency of ferrimagnetic spinels CoFe2O4 and NiFe2O4: We assess the potential of the ferrimagnetic spinel ferrites CoFe2O4 and\nNiFe2O4 to act as spin filtering barriers in magnetic tunnel junctions. Our\nstudy is based on the electronic structure calculated by means of\nfirst-principles density functional theory within different approximations for\nthe exchange correlation energy. We show that, in agreement with previous\ncalculations, the densities of states suggest a lower tunneling barrier for\nminority spin electrons, and thus a negative spin-filter effect. However, a\nmore detailed analysis based on the complex band-structure reveals that both\nsigns for the spin-filtering efficiency are possible, depending on the band\nalignment between the electrode and the barrier materials and depending on the\nspecific wave-function symmetry of the relevant bands within the electrode."
    },
    {
        "anchor": "Spacing Homogenization in Lamellar Eutectic Arrays with Anisotropic\n  Interphase Boundaries: We analyze the effect of interphase boundary anisotropy on the dynamics of\nlamellar eutectic solidification fronts, in the limit that the lamellar spacing\nvaries slowly along the envelope of the front. In the isotropic case, it is\nknown that the spacing obeys a diffusion equation, which can be obtained\ntheoretically by making two assumptions: (i) the lamellae always grow normal to\nthe large-scale envelope of the front, and (ii) the Jackson-Hunt law that links\nlamellar spacing and front temperature remains locally valid. For anisotropic\nboundaries, we replace hypothesis (i) by the symmetric pattern approximation,\nwhich has recently been found to yield good predictions for lamellar growth\ndirection in presence of interphase anisotropy. We obtain a generalized\nJackson-Hunt law for tilted lamellae, and an evolution equation for the\nenvelope of the front. The latter contains a propagative term if the initial\nlamellar array is tilted with respect to the direction of the temperature\ngradient. However, the propagation velocity of the propagative wave modes are\nfound to be small, so that the dynamics of the front can be reasonably\ndescribed by a diffusion equation with a diffusion coefficient that is modified\nwith respect to the isotropic case.",
        "positive": "On the Possibility of Creating Trinary Memory Cells Based on Perforated\n  Magnetic Films: The work examines ferromagnetic films with strong uniaxial anisotropy of the\n\"easy plane\" type and substantiates that paired nano-scaled perforations in\nsuch films can be used as memory cells for recording and storing data in the\nternary number system. The problem of reading the state of cells of this type\nhas been studied, and an approach to solving it has been proposed, which\nconsists in measuring the response of the system to a picosecond pulse of an\nexternal magnetic field. The parameters of the system at which the magnitude of\nthis response is greatest were obtained, and estimates of this value were made\nusing both analytical and numerical methods.\n  --\n  V rabote issleduyutsya ferromagnitnyje plenki s silnoj odnoosnoj anizotropiej\ntipa \"legkaya ploskost\" i obosnovyvaetsya, chto parnyje nanorazmernyje\nperforacii v takih plenkah mogut byt ispolzovany v kachestve yacheek pamyati\ndlya zapisi i hraneniya dannyh v troichnoj sisteme ischisleniya. Izuchena\nproblema schityvaniya sostoyaniya yacheek takogo tipa, a takzhe predlozhen\npodhod k ee resheniyu, zaklyuchayushhijsya v izmerenii otklika sistemy na\npikosekundnyj impuls vneshnego magnitnogo polya. Polucheny parametry sistemy,\npri kotoryh velichina dannogo otklika okazyvaetsya naibolshej, a takzhe\nprovedeny ocenki etoj velichiny kak analiticheskimi, tak i chislennymi\nmetodami."
    },
    {
        "anchor": "Global optimization for accurate determination of EBSD pattern centers: Accurate pattern center determination has long been a challenge for the\nelectron backscatter diffraction (EBSD) community and is becoming critically\naccuracy-limiting for more recent advanced EBSD techniques. Here, we study the\nparameter landscape over which a pattern center must be fitted in quantitative\ndetail and reveal that it is both sloppy and noisy, which limits the accuracy\nto which pattern centers can be determined. To locate the global optimum in\nthis challenging landscape, we propose a combination of two approaches: the use\nof a global search algorithm and averaging the results from multiple patterns.\nWe demonstrate the ability to accurately determine pattern centers of simulated\npatterns, inclusive of effects of binning and noise on the error of the fitted\npattern center. We also demonstrate the ability of this method to accurately\ndetect changes in pattern center in an experimental dataset with noisy and\nhighly binned patterns. Source code for our pattern center fitting algorithm is\navailable online.",
        "positive": "Field-free spin-orbit torque-induced switching of perpendicular\n  magnetization at room temperature in WTe2/ferromagnet heterostructures: Spin-orbit torque (SOT) provides an efficient way to achieve charge-to-spin\nconversion and can switch perpendicular magnetization, which is essential for\ndesigning novel energy-efficient spintronic devices. An out-of-plane SOT could\ndirectly switch perpendicular magnetization. Encouragingly, field-free\nperpendicular magnetization switching of a two-dimensional (2D) material\nWTe2/ferromagnet (FM) bilayer has been reported recently, but the working\ntemperature (200 K) is below room temperature. Here, we report the field-free\nperpendicular magnetization switching carried out at room temperature on a\nWTe2/Pt/Co/Pt multilayer film. Controlled experiments confirm that the\nfield-free switching is caused by the in-plane antidamping SOT generated in the\nPt/Co/Pt multilayer and the out-of-plane generated in the a-axis WTe2 thin\nfilm. This work offers a potential method for using spintronic devices made of\ntwo-dimensional materials at room temperature."
    },
    {
        "anchor": "Massively Parallel Fitting of Gaussian Approximation Potentials: We present a data-parallel software package for fitting Gaussian\nApproximation Potentials (GAPs) on multiple nodes using the ScaLAPACK library\nwith MPI and OpenMP. Until now the maximum training set size for GAP models has\nbeen limited by the available memory on a single compute node. In our new\nimplementation, descriptor evaluation is carried out in parallel with no\ncommunication requirement. The subsequent linear solve required to determine\nthe model coefficients is parallelised with ScaLAPACK. Our approach scales to\nthousands of cores, lifting the memory limitation and also delivering\nsubstantial speedups. This development expands the applicability of the GAP\napproach to more complex systems as well as opening up opportunities for\nefficiently embedding GAP model fitting within higher-level workflows such as\ncommittee models or hyperparameter optimisation.",
        "positive": "Excitation of spin waves on a cylindrical semiconductor heterostructure\n  with Rashba spin-orbit interaction: Elementary excitations in a paramagnetic semiconductor quantum well confined\nto a cylindrical surface are theoretically studied on the basis of coupled\nspin-charge drift-diffusion equations. The electric-field-mediated eigenmodes\nare optically excited by an oscillating interference pattern, which induces a\ncurrent in the outer circuit. For a cylinder with a given radius, sharp\nresonances are predicted to occur in the steady-state current response, which\nare due to weakly damped spin remagnetization waves."
    },
    {
        "anchor": "Graph Neural Network Predictions of Metal Organic Framework CO2\n  Adsorption Properties: The increasing CO2 level is a critical concern and suitable materials are\nneeded to capture such gases from the environment. While experimental and\nconventional computational methods are useful in finding such materials, they\nare usually slow and there is a need to expedite such processes. We use\nAtomistic Line Graph Neural Network (ALIGNN) method to predict CO2 adsorption\nin metal organic frameworks (MOF), which are known for their high functional\ntunability. We train ALIGNN models for hypothetical MOF (hMOF) database with\n137953 MOFs with grand canonical Monte Carlo (GCMC) based CO2 adsorption\nisotherms. We develop high accuracy and fast models for pre-screening\napplications. We apply the trained model on CoREMOF database and\ncomputationally rank them for experimental synthesis. In addition to the CO2\nadsorption isotherm, we also train models for electronic bandgaps, surface\narea, void fraction, lowest cavity diameter, and pore limiting diameter, and\nillustrate the strength and limitation of such graph neural network models. For\na few candidate MOFs we carry out GCMC calculations to evaluate the\ndeep-learning (DL) predictions.",
        "positive": "Strength and structure of carbon-carbon reinforced composite: The atomistic simulations of carbon nanotube (CNT) - carbon reinforced\ncomposite material are reported. The studied composite samples were obtained by\nimpregnating certain amounts of CNTs (3,3) and (6,6) into pristine graphite\nmatrix. The addition of CNTs is found to be of significant usefulness for\nnanotube-reinforced carbon composites since it allows to achieve extreme\nlightness and strength. Being impregnated into graphite matrix, nanotubes are\nable to increase the critical component of its highly anisotropic Young modulus\nby 2-8 times. The linear thermal expansion coefficients do not exceed 1E-5 K-1,\nmaking these composites applicable for aviation and space vehicles. The\ndispersion of CNTs within graphite matrix was found to drastically influence\ncomposite properties."
    },
    {
        "anchor": "Thinned GaInP/GaInAs/Ge solar cells grown with reduced cracking on Ge|Si\n  virtual substrates: Reducing the formation of cracks during growth of GaInP/GaInAs/Ge 3-junction\nsolar cells on Ge|Si virtual substrates has been attempted by thinning the\nstructure, namely the Ge bottom cell and the GaInAs middle cell. The\ntheoretical analysis performed using realistic device parameters indicates that\nthe GaInAs middle cell can be drastically thinned to 1000 nm while increasing\nits In content to 8% with an efficiency loss in the 3-junction cell below 3%.\nThe experimental results show that the formation of macroscopic cracks is\nprevented in thinned GaInAs/Ge 2-junction and GaInP/GaInAs/Ge 3-junction cells.\nThese prototype crack-free multijunction cells demonstrate the concept and were\nused to rule out any possible component integration issue. The performance\nmetrics are limited by the high threading dislocation density over 2e7cm-2 in\nthe virtual substrates used, but an almost current matched, crack-free, thinned\n3-junction solar cell is demonstrated, and the pathway towards solar cells with\nhigher voltages identified.",
        "positive": "All-in/all-out magnetic domains: X-ray diffraction imaging and magnetic\n  field control: Long-range non-collinear all-in/all-out magnetic order has been directly\nobserved for the first time in real space in the pyrochlore Cd$_2$Os$_2$O$_7$\nusing resonant magnetic microdiffraction at the Os L$_3$ edge. Two different\nantiferromagnetic domains related by time-reversal symmetry could be\ndistinguished and have been mapped within the same single crystal. The two\ntypes of domains are akin to magnetic twins and were expected - yet unobserved\nso far - in the all-in/all-out model. Even though the magnetic domains are\nantiferromagnetic, we show that their distribution can be controlled using a\nmagnetic field-cooling procedure."
    },
    {
        "anchor": "Reversible spin texture in ferroelectric HfO2: Spin-orbit coupling effects occurring in non-centrosymmetric materials are\nknown to be responsible for non-trivial spin configurations and a number of\nemergent physical phenomena. Ferroelectric materials may be especially\ninteresting in this regard due to reversible spontaneous polarization making\npossible for a non-volatile electrical control of the spin degrees of freedom.\nHere, we explore a technologically relevant oxide material, HfO2, which has\nbeen shown to exhibit robust ferroelectricity in a non-centrosymmetric\northorhombic phase. Using theoretical modelling based on density-functional\ntheory, we investigate the spin-dependent electronic structure of the\nferroelectric HfO2 and demonstrate the appearance of chiral spin textures\ndriven by spin-orbit coupling. We analyze these spin configurations in terms of\nthe Rashba and Dresselhaus effects within the k.p Hamiltonian model and find\nthat the Rashba-type spin texture dominates around the valence band maximum,\nwhile the Dresselhaus-type spin texture prevails around the conduction band\nminimum. The latter is characterized by a very large Dresselhaus constant\n{\\alpha}D = 0.578 eV {\\AA}, which allows using this material as a tunnel\nbarrier to produce tunneling anomalous and spin Hall effects that are\nreversible by ferroelectric polarization.",
        "positive": "Strain broadening of the 1042-nm zero-phonon line of the NV- center in\n  diamond: a promising spectroscopic tool for defect tomography: The negatively charged nitrogen-vacancy (NV-) center in diamond is a\npromising candidate for many quantum applications. Here, we examine the\nsplitting and broadening of the center's infrared (IR) zero-phonon line (ZPL).\nWe develop a model for these effects that accounts for the strain induced by\nphoto-dependent microscopic distributions of defects. We apply this model to\ninterpret observed variations of the IR ZPL shape with temperature and\nphotoexcitation conditions. We identify an anomalous temperature dependent\nbroadening mechanism and that defects other than the substitutional nitrogen\ncenter significantly contribute to strain broadening. The former conclusion\nsuggests the presence of a strong Jahn-Teller effect in the center's singlet\nlevels and the latter indicates that major sources of broadening are yet to be\nidentified. These conclusions have important implications for the understanding\nof the center and the engineering of diamond quantum devices. Finally, we\npropose that the IR ZPL can be used as a sensitive spectroscopic tool for\nprobing microscopic strain fields and performing defect tomography."
    },
    {
        "anchor": "The current-induced spin-orbit torque and field-free switching from\n  Mo-based magnetic heterostructures: Magnetic heterostructure Mo/CoFeB/MgO has strong perpendicular magnetic\nanisotropy and thermal stability. Through current-induced hysteresis loop shift\nmeasurements, we show that the dampinglike spin-orbit torque (SOT) efficiency\nof Mo/CoFeB/MgO heterostructure is $\\xi_{DL}\\approx -0.003\\pm 0.001$ and fairly\nindependent of the annealing temperature from 300$^\\circ$C to 400$^\\circ$C.\nThough $|\\xi_{DL}|$ is small while compare to those from Ta or W-based\nheterostructures, reversible current-induced SOT switching of a\nthermally-stable Mo/CoFeB/MgO heterostruture can still be achieved.\nFurthermore, we observe field-free current-induced switching from a\nMo/CoFeB/MgO structure with the Mo layer being wedge-deposited. Our results\nindicate that even for a weak spin-orbit interaction 4d transition metal such\nas Mo, it is still possible to generate sufficient spin current for\nconventional SOT switching and to realize field-free current-induced switching\nby structural engineering.",
        "positive": "Coulomb Explosion and Thermal Spikes: A fast ion penetrating a solid creates a track of excitations. This can\nproduce displacements seen as an etched track, a process initially used to\ndetect energetic particles but now used to alter materials. From the seminal\npapers by Fleischer et al. [Phys. Rev. 156, 353 (1967)] to the present [C.\nTrautmann, S. Klaumunzer and H. Trinkaus, Phys. Rev. Lett. 85, 3648 (2000)],\n`Coulomb explosion' and thermal spike models are treated as conflicting models\nfor describing ion track effects. Here molecular dynamics simulations of\nelectronic-sputtering, a surface manifestation of ion track formation, show\nthat `Coulomb explosion' produces a `heat' spike so that these are early and\nlate aspects of the same process. Therefore, differences in scaling are due to\nthe use of incomplete spike models."
    },
    {
        "anchor": "Spin-Wave Resonance Model of Surface Pinning in Ferromagnetic\n  Semiconductor (Ga,Mn)As Thin Films: The source of spin-wave resonance (SWR) in thin films of the ferromagnetic\nsemiconductor (Ga,Mn)As is still under debate: does SWR stem from the\n\\emph{surface} anisotropy (in which case the surface inhomogeneity (SI) model\nwould apply), or does it originate in the \\emph{bulk} inhomogeneity of the\nmagnetic structure of the sample (and thus requires the use of the volume\ninhomogeneity (VI) model)? This paper outlines the ground on which the\ncontroversy arose and shows why in different conditions a resonance sample may\nmeet the assumptions of either the SI or the VI model. In our considerations we\nrefer to the SWR spectra measured by Furdyna's team [X. Liu \\textit{et al.},\nPhysical Review B \\textbf{75}, 195220 (2007)] in (Ga,Mn)As thin films in\ndifferent configurations of the static magnetic field $\\vec{H}$ with respect to\nthe surface. We demonstrate that the observed configuration dependence of the\nSWR spectrum of the studied material can be described with the use of the\nsurface pinning parameter.",
        "positive": "Dimensional Crossover Induced Topological Hall Effect in a Magnetic\n  Topological Insulator: We report transport studies of Mn-doped Bi2Te3 topological insulator (TI)\nfilms with accurately controlled thickness grown by molecular beam epitaxy. We\nfind that films thicker than 5 quintuple-layer (QL) exhibit the usual anomalous\nHall effect for magnetic TIs. When the thickness is reduced to 4 QL, however,\ncharacteristic features associated with the topological Hall effect (THE)\nemerge. More surprisingly, the THE vanishes again when the film thickness is\nfurther reduced to 3 QL. Theoretical calculations demonstrate that the coupling\nbetween the top and bottom surface states at the dimensional crossover regime\nstabilizes the magnetic skyrmion structure that is responsible for the THE."
    },
    {
        "anchor": "Crystal structure informed mesoscale deformation model for HCP Cu6Sn5\n  intermetallic compound: In the electronic packaging and energy storage sectors, the study of Cu6Sn5\nintermetallic compound (IMC) is getting more attention. At temperatures above\n186 oC, this IMC exists in a hexagonal closed packed (HCP) crystalline\nstructure. Crystal plasticity finite element simulations are performed on\nCu6Sn5 IMC by taking the information about its lattice parameters and direction\ndependent elastic properties. Three types of models corresponding to\ndeformations in basal, prismatic and pyramidal modes are developed. With the\nsame type of loading in the elastic regime and boundary conditions, the results\nof the computations reveal the differences in displacement magnitudes among the\nthree model types.",
        "positive": "High-Voltage Honeycomb Layered Oxide Positive Electrodes for\n  Rechargeable Sodium Batteries: Natural abundance, impressive chemical characteristics and economic\nfeasibility have rekindled the appeal for rechargeable sodium (Na) batteries as\na practical solution for the growing energy demand, environmental\nsustainability and energy independence. However, the scarcity of viable\npositive electrode materials remains a huge impediment to the actualization of\nthis technology. In this paper, we explore honeycomb layered oxides adopting\nthe composition Na$_2$Ni$_{2-x}$Co$_x$TeO$_6$ ($x = 0, 0.25$ and $0.50$) as\nfeasible positive electrode (cathode) materials for rechargeable sodium\nbatteries at both room- and elevated temperatures using ionic liquids. Through\nstandard galvanostatic assessments and analyses we demonstrate that\nsubstitution of nickel with cobalt in Na$_2$Ni$_2$TeO$_6$ leads to an increase\nin the discharge voltage to nearly $4$ V (versus Na$^+$ / Na) for the\nNa$_2$Ni$_{2-x}$Co$_x$TeO$_6$ family of honeycomb layered oxide materials,\nwhich surpasses the attained average voltages for most layered oxide positive\nelectrode materials that facilitate Na-ion desertion. We also verify the\nincreased kinetics within the Na$_2$Ni$_{2-x}$Co$_x$TeO$_6$ honeycomb layered\noxides during operations at elevated temperatures which lead to an increase in\nreversible capacity of the rechargeable Na battery. This study underpins the\ndoping of congener transition metal atoms to the honeycomb structure of\nNa$_2$Ni$_2$TeO$_6$ in addition to elevated-temperature operation as a\njudicious route to enhance the electrochemical performance of analogous layered\noxides."
    },
    {
        "anchor": "Spin-polarized quantum transport properties through flexible phosphorene: We report a first-principles study on the tunnel magnetoresistance (TMR) and\nspin-injection efficiency (SIE) through phosphorene with nickel electrodes\nunder the mechanical tension and bending on the phosphorene region. Both the\nTMR and SIE are largely improved under these mechanical deformations. For the\nuniaxial tension ($\\varepsilon_y$) varying from 0 to 15\\% applied along the\narmchair transport ({\\it y}-)direction of the phosphorene, the TMR ratio is\nenhanced with a maximum of 107\\% at the $\\varepsilon_y=10\\%$, while the SIE\nincreases monotonously from 8\\% up to 43\\% with the increasing of the strain.\nUnder the out-of-plane bending, the TMR overall increases from 7\\% to 50\\%\nwithin the bending ratio of 0-3.9\\%, and meanwhile the SIE is largely improved\nto around 70\\%, as compared to that (30\\%) of the flat phosphorene. Such\nbehaviors of the TMR and SIE are mainly affected by the transmission of spin-up\nelectrons in the parallel configuration, which is highly depended on the\napplied mechanical tension and bending. Our results indicate that the\nphosphorene based tunnel junctions have promising applications in flexible\nelectronics.",
        "positive": "The rise of 212 MAX phase borides, Ti$_2$PB$_2$, Zr$_2$PbB$_2$, and\n  Nb$_2$AB$_2$ [A = P, S]: DFT insights into the physical properties for\n  thermo-mechanical applications: An interesting class of ternary metallic borides, known as the 212 MAX phase\nborides, is the recent advancement of the MAX phase family. In this article,\nresults from ab-initio calculations on unexplored Ti$_2$PB$_2$, Zr$_2$PbB$_2$,\nand Nb$_2$AB$_2$ [A = P, S] are reported wherein Ti$_2$PB$_2$ along with its\n211 boride phase Ti$_2$PB are predicted for the first time. The stability was\nconfirmed by calculating the formation energy, phonon dispersion curve, and\nelastic stiffness constants. The obtained elastic constants, elastic moduli,\nand Vickers hardness values of Ti$_2$PB$_2$, Zr$_2$PbB$_2$, and Nb$_2$AB$_2$ [A\n= P, S] were found to be significantly larger than those of their counterparts\n211 borides and carbides, in a trend similar to other 212 borides. The studied\ncompounds are brittle like most of the MAX and MAB phases. The electronic band\nstructure and density of states revealed the metallic nature of the titled\nborides. Several thermal parameters were explored, certifying the suitability\nof Ti2PB2, Zr2PbB2, and Nb2AB2 [A = P, S] compared to their counterparts, and a\nsimilar trend was found for the other 212 borides. The obtained results predict\nthat Ti2PB2, Zr2PbB2, and Nb2AB2 [A = P, S] have significant potential for use\nas efficient thermal barrier coating materials. The response of Ti$_2$PB$_2$,\nZr$_2$PbB$_2$, and Nb$_2$AB$_2$ [A = P, S] to the incident photon was studied\nby computing the dielectric constant (real and imaginary part), refractive\nindex, absorption coefficient, photoconductivity, reflectivity, and energy loss\nfunction. The ability to protect from solar heating was revealed from the\nstudied reflectivity spectra. In this work, we have explored the physical basis\nof the improved thermo-mechanical properties of 212 MAX phase borides compared\nto their carbide and boride counterparts."
    },
    {
        "anchor": "Analytical model to predict the effect of a finite impedance surface on\n  the propagation properties of a 2D Sonic Crystal: The use of Sonic Crystals as environmental noise barriers has certain\nadvantages from the acoustical and the constructive point of view with regard\nto conventional ones. One aspect do not studied yet is the acoustic interaction\nbetween the Sonic Crystals and the ground due to, up to now, this latter is not\nincluded in the analytical models used to characterize these Sonic Crystals. We\npresent here an analytical model, based on multiple scattering theory, to study\nthis interaction considering the ground as a finite impedance surface. Using\nthis model we have obtained interesting conclusions that allow to design more\neffectively noise screens based on Sonic Crystals. The obtained results have\nbeen compared with experimental and numerical, finding a good agreement between\nthem.",
        "positive": "Molecular Identification from AFM images using the IUPAC Nomenclature\n  and Attribute Multimodal Recurrent Neural Networks: Despite being the main tool to visualize molecules at the atomic scale, AFM\nwith CO-functionalized metal tips is unable to chemically identify the observed\nmolecules. Here we present a strategy to address this challenging task using\ndeep learning techniques. Instead of identifying a finite number of molecules\nfollowing a traditional classification approach, we define the molecular\nidentification as an image captioning problem. We design an architecture,\ncomposed of two multimodal recurrent neural networks, capable of identifying\nthe structure and composition of an unknown molecule using a 3D-AFM image stack\nas input. The neural network is trained to provide the name of each molecule\naccording to the IUPAC nomenclature rules. To train and test this algorithm we\nuse the novel QUAM-AFM dataset, which contains almost 700,000 molecules and 165\nmillion AFM images. The accuracy of the predictions is remarkable, achieving a\nhigh score quantified by the cumulative BLEU 4-gram, a common metric in\nlanguage recognition studies."
    },
    {
        "anchor": "Overscreening and Underscreening in Solid-Electrolyte Grain Boundary\n  Space-Charge Layers: Polycrystalline solids can exhibit material properties that differ\nsignificantly from those of equivalent single-crystal samples, in part, because\nof a spontaneous redistribution of mobile point defects into so-called\nspace-charge regions adjacent to grain boundaries. The general analytical form\nof these space-charge regions is known only in the dilute limit, where\ndefect-defect correlations can be neglected. Using kinetic Monte Carlo\nsimulations of a three-dimensional Coulomb lattice gas, we show that\ngrain-boundary space-charge regions in non-dilute solid electrolytes exhibit\noverscreening -- damped oscillatory space-charge profiles -- and underscreening\n-- decay lengths that are longer than the corresponding Debye length and that\nincrease with increasing defect-defect interaction strength. Overscreening and\nunderscreening are known phenomena in concentrated liquid electrolytes, and the\nobservation of functionally analogous behaviour in solid electrolyte\nspace-charge regions suggests that the same underlying physics drives behaviour\nin both classes of systems. We therefore expect theoretical approaches\ndeveloped to study non-dilute liquid electrolytes to be equally applicable to\nfuture studies of solid electrolytes.",
        "positive": "Current-induced magnetization reversal in (Ga,Mn)(Bi,As) epitaxial layer\n  with perpendicular magnetic anisotropy: Pulsed current-induced magnetization reversal is investigated in the layer of\n(Ga,Mn)(Bi,As) dilute ferromagnetic semiconductor (DFS) epitaxially grown under\ntensile misfit strain causing perpendicular magnetic anisotropy in the layer.\nThe magnetization reversal, recorded through measurements of the anomalous Hall\neffect, appearing under assistance of a static magnetic field parallel to the\ncurrent, is interpreted in terms of the spin-orbit torque mechanism. Our\nresults demonstrate that an addition of a small fraction of heavy Bi atoms,\nsubstituting As atoms in the prototype DFS (Ga,Mn)As and increasing the\nstrength of spin-orbit coupling in the DFS valence band, significantly enhances\nthe efficiency of current-induced magnetization reversal thus reducing\nconsiderably the threshold current density necessary for the reversal. Our\nfindings are of technological importance for applications to spin-orbit\ntorque-driven nonvolatile memory and logic elements."
    },
    {
        "anchor": "Theory of nonlinear dc conductivity, longitudinal and transverse: Kohn's theory of Drude conductivity, established in a many-body framework,\naddresses even systems with disorder and correlation, besides the ordinary band\nmetals (i.e. crystalline systems of independent electrons). Kohn's theory is\nhere extended to nonlinear dc conductivities of arbitrary order, longitudinal\nand transverse. The results are then reformulated in a band-structure\nframework, and their relationships to the semiclassical theory of nonlinear\nelectron transport are elucidated.",
        "positive": "First-principles study of the mobility of SrTiO$_3$: We investigate the electronic and vibrational spectra of SrTiO$_3$, as well\nas the coupling between them, using first-principles calculations. We compute\nelectron-phonon scattering rates for the three lowest-energy conduction bands\nand use Boltzmann transport theory to calculate the room-temperature mobility\nof SrTiO$_3$. The results agree with experiment and highlight the strong impact\nof longitudinal optical phonon scattering. Our analysis provides important\ninsights into the key factors that determine room temperature mobility, such as\nthe number of conduction bands and the nature and frequencies of longitudinal\nphonons. Such insights provide routes to engineering materials with enhanced\nmobilities."
    },
    {
        "anchor": "Fracture in distortion gradient plasticity: In this work, distortion gradient plasticity is used to gain insight into\nmaterial deformation ahead of a crack tip. This also constitutes the first\nfracture mechanics analysis of gradient plasticity theories adopting Nye's\ntensor as primal kinematic variable. First, the asymptotic nature of crack tip\nfields is analytically investigated. We show that an inner elastic region\nexists, adjacent to the crack tip, where elastic strains dominate plastic\nstrains and Cauchy stresses follow the linear elastic stress singularity. This\nfinding is verified by detailed finite element analyses using a new numerical\nframework, which builds upon a viscoplastic constitutive law that enables\ncapturing both rate-dependent and rate-independent behaviour in a\ncomputationally efficient manner. Numerical analysis is used to gain further\ninsight into the stress elevation predicted by distortion gradient plasticity,\nrelative to conventional J2 plasticity, and the influence of the plastic spin\nunder both mode I and mixed-mode fracture conditions. It is found that Nye's\ntensor contributions have a weaker effect in elevating the stresses in the\nplastic region, while predicting the same asymptotic behaviour as constitutive\nchoices based on the plastic strain gradient tensor. A minor sensitivity to X,\nthe parameter governing the dissipation due to the plastic spin, is observed.\nFinally, distortion gradient plasticity and suitable higher order boundary\nconditions are used to appropriately model the phenomenon of brittle failure\nalong elastic-plastic material interfaces. We reproduce paradigmatic\nexperiments on niobium-sapphire interfaces and show that the combination of\nstrain gradient hardening and dislocation blockage leads to interface crack tip\nstresses that are larger than the theoretical lattice strength, rationalising\ncleavage in the presence of plasticity at bi-material interfaces.",
        "positive": "Diffuse Neutron Scattering Study of a Disordered Complex Perovskite\n  Pb(Zn1/3Nb2/3)O3 Crystal: Diffuse scattering around the (110) reciprocal lattice point has been\ninvestigated by elastic neutron scattering in the paraelectric and the relaxor\nphases of the disordered complex perovskite crystal-Pb(Zn1/3Nb2/3)O3(PZN). The\nappearance of a diffuse intensity peak indicates the formation of polar\nnanoregions at temperature T*, approximately 40K above Tc=413K. The analysis of\nthis diffuse scattering indicates that these regions are in the shape of\nellipsoids, more extended in the <111> direction than in the <001> direction.\nThe quantitative analysis provides an estimate of the correlation length, \\xi,\nor size of the regions and shows that \\xi <111>~1.2\\xi < 001>, consistent with\nthe primary or dominant displacement of Pb leading to the low temperature\nrhombohedral phase. Both the appearance of the polar regions at T*and the\nstructural transition at Tc are marked by kinks in the \\xi < 111> curve but not\nin the \\xi < 001> one, also indicating that the primary changes take place in a\n<111> direction at both temperatures."
    },
    {
        "anchor": "Stable compounds in the CaO-Al2O3 system at high pressures: Using evolutionary crystal structure prediction algorithm USPEX, we showed\nthat at pressures of the Earth's lower mantle CaAl2O4 is the only stable\ncalcium aluminate. At pressures above 7.0 GPa it has the CaFe2O4-type structure\nand space group Pnma. This phase is one of prime candidate aluminous phases in\nthe lower mantle of the Earth. We show that at low pressures 5CaO * 3Al2O3\n(C5A3) with space group Cmc21, CaAl4O7 (C2/c) and CaAl2O4 (P21/m) structures\nare stable at pressures of up to 2.1, 1.8 and 7.0 GPa respectively. The\npreviously unknown structure of the orthorhombic 'CA-III' phase is also found\nfrom our calculations. This phase is metastable and has a layered structure\nwith space group P21212.",
        "positive": "Advancing from phenomenological to predictive theory of ferroelectric\n  oxide solution properties through consideration of domain walls: Prediction of properties from composition is a fundamental goal of materials\nscience and can greatly accelerate development of functional materials. It is\nparticularly relevant for ferroelectric perovskite solid solutions where\ncompositional variation is a primary tool for materials design. To advance\nbeyond the commonly used Landau-Ginzburg-Devonshire and density functional\ntheory methods that despite their power are not predictive, we elucidate the\nkey interactions that govern ferroelectrics using 5-atom bulk unit cells and\nnon-ground-state defect-like ferroelectric domain walls as a simple as possible\nbut not simpler model systems. We also develop a theory relating properties at\nseveral different length scales that provides a unified framework for the\nprediction of ferroelectric, antiferroelectric and ferroelectric phase\nstabilities and the key transition temperature, coercive field and polarization\nproperties from composition. The elucidated physically meaningful relationships\nenable rapid identification of promising piezoelectric and dielectric\nmaterials."
    },
    {
        "anchor": "Equations of state and stability of MgSiO$_3$ perovskite and\n  post-perovskite phases from quantum Monte Carlo simulations: We have performed quantum Monte Carlo (QMC) simulations and density\nfunctional theory (DFT) calculations to study the equations of state of\nMgSiO$_3$ perovskite (Pv) and post-perovskite (PPv), up to the pressure and\ntemperature conditions of the base of Earth's lower mantle. The ground state\nenergies were derived using QMC and the temperature dependent Helmholtz free\nenergies were calculated within the quasi-harmonic approximation and density\nfunctional perturbation theory. The equations of state for both phases of\nMgSiO$_3$ agree well with experiments, and better than those from generalized\ngradient approximation (GGA) calculations. The Pv-PPv phase boundary calculated\nfrom our QMC equations of states is also consistent with experiments, and\nbetter than previous LDA calculations. We discuss the implications for double\ncrossing of the Pv-PPv boundary in the Earth.",
        "positive": "Transport properties of iron at the Earth's core conditions: the effect\n  of spin disorder: The electronic and thermal transport properties of the Earth's core are\ncrucial for many geophysical models such as the geodynamo model of the Earth's\nmagnetic field and of its reversals. Here we show, by considering bcc-iron and\niron-rich iron-silicon alloy as a representative of the Earth's core\ncomposition and applying the first-principles modeling that the spin disorder\nat the Earth's core conditions provides an essential contribution, of order\n20~$\\mu\\Omega$\\,cm, to the electrical resistivity. This value is comparable in\nmagnitude with the electron-phonon and with the recently estimated\nelectron-electron scattering contributions. The origin of the spin-disorder\nresistivity (SDR) consists in the existence of fluctuating local moments that\nare stabilized at high temperatures by the magnetic entropy even at pressures\nat which the ground state of iron is non-magnetic. We find that electron-phonon\nand SDR contributions are not additive at high temperatures. We thus observe a\nlarge violation of the Matthiessen rule, not common in conventional metallic\nalloys at ambient conditions."
    },
    {
        "anchor": "Spin Polarized and Valley Helical Edge Modes in Graphene Nanoribbons: Inspired by recent progress in fabricating precisely zigzag-edged graphene\nnanoribbons and the observation of edge magnetism, we find that spin polarized\nedge modes with well-defined valley index can exist in a bulk energy gap opened\nby a staggered sublattice potential such as that provided by a hexagonal\nBoron-Nitride substrate. Our result is obtained by both tight-binding model and\nfirst principles calculations. These edge modes are helical with respect to the\nvalley degree of freedom, and are robust against scattering, as long as the\ndisorder potential is smooth over atomic scale, resulting from the protection\nof the large momentum separation of the valleys.",
        "positive": "Electronic structure and magnetism of equiatomic FeN: In order to investigate the phase stability of equiatomic FeN compounds and\nthe structure-dependent magnetic properties, the electronic structure and total\nenergy of FeN with NaCl, ZnS and CsCl structures and various magnetic\nconfigurations are calculated using the first-principles TB-LMTO-ASA method.\nAmong all the FeN phases considered, the antiferromagnetic NaCl structure with\nq=(00pi) is found to have the lowest energy at the theoretical equilibrium\nvolume. However, the FM NaCl phase lies only 1mRyd higher. The estimated\nequilibrium lattice constant for nonmagnetic ZnS-type FeN agrees quite well\nwith the experimental value, but for the AFM NaCl phase the estimated value is\n6.7% smaller than that observed experimentally. For ZnS-type FeN, metastable\nmagnetic states are found for volumes larger than the equilibrium value. On the\nbasis of an analysis of the atom- and orbital-projected density of states and\norbital-projected Crystal Orbital Hamilton Population, the iron-nitrogen\ninteractions in NM ZnS, AFM NaCl and FM CsCl structures are discussed. The\nleading Fe-N interactions is due to the d-p iron-nitrogen hybridization, while\nconsiderable s-p and p-p hybridizations are also observed in all three phases.\nThe iron magnetic moment in FeN is found to be highly sensitive to the\nnearest-neighboring Fe-N distance. In particular, the magnetic moment shows an\nabrupt drop from a value of about 2 muB to zero with the reduction of the Fe-N\ndistance for the ZnS and CsCl structures."
    },
    {
        "anchor": "Causal Discovery to Understand Hot Corrosion: Gas turbine superalloys experience hot corrosion, driven by factors including\ncorrosive deposit flux, temperature, gas composition, and component material.\nThe full mechanism still needs clarification and research often focuses on\nlaboratory work. As such, there is interest in causal discovery to confirm the\nsignificance of factors and identify potential missing causal relationships or\nco-dependencies between these factors. The causal discovery algorithm Fast\nCausal Inference (FCI) has been trialled on a small set of laboratory data,\nwith the outputs evaluated for their significance to corrosion propagation, and\ncompared to existing mechanistic understanding. FCI identified the salt\ndeposition flux as the most influential corrosion variable for this limited\ndataset. However, HCl was the second most influential for pitting regions,\ncompared to temperature for more uniformly corroding regions. Thus FCI\ngenerated causal links aligned with literature from a randomised corrosion\ndataset, while also identifying the presence of two different degradation modes\nin operation.",
        "positive": "Quantifying the Dzyaloshinskii-Moriya Interaction Induced by the Bulk\n  Magnetic Asymmetry: A broken interfacial inversion symmetry in ultrathin ferromagnet/heavy metal\n(FM/HM) bilayers is generally believed to be a prerequisite for accommodating\nthe Dzyaloshinskii-Moriya interaction (DMI) and for stabilizing chiral spin\ntextures. In these bilayers, the strength of the DMI decays as the thickness of\nthe FM layer increases and vanishes around a few nanometers. In the present\nstudy, through synthesizing relatively thick films of compositions CoPt or\nFePt, CoCu or FeCu, FeGd and FeNi, contributions to DMI from the composition\ngradient induced bulk magnetic asymmetry (BMA) and spin-orbit coupling (SOC)\nare systematically examined. Using Brillouin light scattering spectroscopy,\nboth the sign and amplitude of DMI in films with controllable direction and\nstrength of BMA, in the presence and absence of SOC are experimentally studied.\nIn particular, we show that a sizable amplitude of DMI (0.15 mJ/m^2) can be\nrealized in CoPt or FePt films with BMA and strong SOC, whereas negligible DMI\nstrengths are observed in other thick films with BMA but without significant\nSOC. The pivotal roles of BMA and SOC are further examined based on the\nthree-site Fert-Levy model and first-principles calculations. It is expected\nthat our findings may help to further understand the origin of chiral magnetism\nand to design novel non-collinear spin textures."
    },
    {
        "anchor": "Magnetic Bubblecade Memory: Unidirectional motion of magnetic domain walls is the key concept underlying\nnext-generation domain-wall-mediated memory and logic devices. Such motion has\nbeen achieved either by injecting large electric currents into nanowires or by\nemploying domain-wall tension induced by sophisticated structural modulation.\nHerein, we demonstrate a new scheme without any current injection or structural\nmodulation. This scheme utilizes the recently discovered chiral domain walls,\nwhich exhibit asymmetry in their speed with respect to magnetic fields. Because\nof this asymmetry, an alternating magnetic field results in the coherent motion\nof the domain walls in one direction. Such coherent unidirectional motion is\nachieved even for an array of magnetic bubble domains, enabling the design of a\nnew device prototype-magnetic bubblecade memory-with two-dimensional\ndata-storage capability.",
        "positive": "Controlled defects in ZnO by low energy Ar irradiation: We report interesting observations in 1.2 MeV Ar8+ ion irradiated ZnO which,\nto the best of our knowledge, have not been published earlier and will be\nuseful for the scientific community engaged in research on ZnO. Irradiation\nwith the initial fluence 1 X 10^15 ions/cm^2 changes the colour of the sample\nfrom white to orange while the highest irradiation fluence makes it dark\nreddish brown that appears as black. Such changes in colour can be correlated\nwith the oxygen vacancy type defects. No significant change in the grain size\nof the irradiated samples, as revealed from the x-ray diffraction (XRD) line\nwidth broadening, has been observed. Increase of surface roughness due to\nsputtering is clearly visible in scanning electron micrographs (SEM) with\nhighest fluence of irradiation. Room temperature Photoluminescence (PL)\nspectrum of the unirradiated sample shows intense ultra-violet (UV) emission (~\n3.27 eV) and less prominent defect level emissions (2-3 eV). The overall\nemission is largely quenched due to initial irradiation fluence. But with\nincreasing fluence UV emission is enhanced along with prominent defect level\nemissions. Remarkably, the resistivity of the irradiated sample with highest\nfluence is reduced by four orders of magnitude compared to that of the\nunirradiated sample. This indicates increase of donor concentration as well as\ntheir mobility due to irradiation. Oxygen vacancies are deep donors in ZnO, but\nsurely they influence the stability of the shallow donors (presumably zinc\ninterstitial related) and vice versa. This is in conformity with recent\ntheoretical calculations."
    },
    {
        "anchor": "On a universal relation for defects in solids: We show that the defect data parameters related to various defect processes,\ne.g., formation, migration, dielectric relaxation parameters, obey a universal\nlaw. In particular, the defect entropies scale with the defect enthalpies\nirrespective of the process considered. A concrete example is given here for\nSrF$_2$ by considering the dielectric relaxation parameters (R$_1$ relaxation\nmechanism) for crystals doped with trivalent ions of Ce, Eu and Gd, parameters\nfor the anion Frenkel formation as well as for the migration of anion vacancy\nand the anion interstitial motion.",
        "positive": "Canted antiferromagnetic order in the monoaxial chiral magnets\n  V$_{1/3}$TaS$_2$ and V$_{1/3}$NbS$_{2}$: The Dzyaloshinskii-Moriya (DM) interaction is present in the transition metal\ndichalcogenides (TMDC) magnets of form $M_{1/3}T$S$_{2}$ ($M$ $=$ 3d transition\nmetal, $T$ $\\in$ {Nb, Ta}), given that the intercalants $M$ form\n$\\sqrt{3}\\times\\sqrt{3}$ superlattices within the structure of the parent\nmaterials $T$S$_2$ and break the centrosymmetry. Competition between the DM and\nferromagnetic exchange interactions in these systems has been shown to\nstabilize a topological defect known as a chiral soliton in select intercalated\nTMDCs, initiating interest both in terms of fundamental physics and the\npotential for technological applications. In the current article, we report on\nour study of the materials V$_{1/3}$TaS$_2$ and V$_{1/3}$NbS$_2$, using a\ncombination of x-ray powder diffraction, magnetization and single crystal\nneutron diffraction. Historically identified as ferromagnets, our diffraction\nresults instead reveal that vanadium spins in these compounds are arranged into\nan A-type antiferromagnetic configuration at low temperatures. Refined moments\nare 1.37(6)$\\mu_{B}$ and 1.50(9)$\\mu_{B}$ for V$_{1/3}$TaS$_2$ and\nV$_{1/3}$NbS$_2$, respectively. Transition temperatures $T_{c}$~$=$~32K for\nV$_{1/3}$TaS$_{2}$ and 50K for V$_{1/3}$NbS$_{2}$ are obtained from the\nmagnetization and neutron diffraction results. We attribute the small net\nmagnetization observed in the low-temperature phases to a subtle\n($\\sim$2$^{\\circ}$) canting of XY-spins in the out-of-plane direction. These\nnew results are indicative of dominant antiferromagnetic exchange interactions\nbetween the vanadium moments in adjacent ab-planes, likely eliminating the\npossibility of identifying stable chiral solitons in the current materials."
    },
    {
        "anchor": "Direct in-situ measurement of electrical properties of solid electrolyte\n  interphase on lithium metal anode: Solid electrolyte interphase (SEI), a thin layer that dynamically forms\nbetween active electrode and electrolyte during battery operation, critically\ngoverns the performance of rechargeable batteries1-5. An ideal SEI is expected\nto be electrically insulative to prevent persistently parasitic reactions\nbetween the electrode and the electrolyte, while ionically conductive to\nfacilitate Faradaic reactions of the electrode1,2,6. However, the true nature\nof the electrical properties of an SEI layer remains hitherto unclear due to\nthe lack of a direct characterization method, leaving a range of behaviors of\nrechargeable batteries unelucidated. Here, we use in-situ bias transmission\nelectron microscopy, for the first time, to directly measure the electrical\nproperties of SEIs formed on copper (Cu) and lithium (Li) substrates.\nSurprisingly, we discover that, in terms of electrical behavior, SEI is\ndistinctively different from a typical electrical insulator as what has been\nwidely, and up to date, assumed ever since the discovery of SEI; rather, SEI\nshows voltage-dependent differential conductance.",
        "positive": "Electronic Excitations from a Perturbative LDA+GdW Approach: We discuss an efficient approach to excited electronic states within\nab-initio many-body perturbation theory (MBPT). Quasiparticle corrections to\ndensity-functional theory result from the difference between metallic and\nnon-metallic dielectric screening. They are evaluated as a small perturbation\nto the DFT-LDA band structure, rather than fully calculating the self energy\nand evaluating its difference from the exchange-correlation potential. The\ndielectric screening is desribed by a model, which applies to bulk crystals, as\nwell as, to systems of reduced dimension, like molecules, surfaces, interfaces,\nand more. The approach also describes electron-hole interaction. The resulting\nelectronic and optical spectra are slightly less accurate but much faster to\ncalculate than a full MBPT calculation. We discuss results for bulk silicon and\nargon, for the Si(111)-(2x1) surface, the SiH4 molecule, an argon-aluminum\ninterface, and liquid argon."
    },
    {
        "anchor": "Properties of the ferrimagnetic double-perovskite A_{2}FeReO_{6} (A=Ba\n  and Ca): Ceramics of A_{2}FeReO_{6} double-perovskite have been prepared and studied\nfor A=Ba and Ca. Ba_{2}FeReO_{6} has a cubic structure (Fm3m) with $a\\approx\n$8.0854(1) \\AA whereas Ca_{2}FeReO_{6} has a distorted monoclinic symmetry with\n$a\\approx 5.396(1) \\AA, b\\approx 5.522(1) \\AA, c\\approx 7.688(2) \\AA$ and\n$\\beta =90.4^{\\circ} (P21/n)$. The barium compound is metallic from 5 K to 385\nK, i.e. no metal-insulator transition has been seen up to 385 K, and the\ncalcium compound is semiconducting from 5 K to 385 K. Magnetization\nmeasurements show a ferrimagnetic behavior for both materials, with T_{c}=315 K\nfor Ba_{2}FeReO_{6} and above 385 K for Ca_{2}FeReO_{6}. A specific heat\nmeasurement on the barium compound gave an electron density of states at the\nFermi level, N(E_{F}) equal to 6.1$\\times 10^{24} eV^{-1}mole^{-1}$. At 5 K, we\nobserved a negative magnetoresistance of 10 % in a magnetic field of 5 T, but\nonly for Ba_{2}FeReO_{6}. Electrical, thermal and magnetic properties are\ndiscussed and compared to the analogous compounds Sr_{2}Fe(Mo,Re)O_{6}.",
        "positive": "Spin pumping and spin torque in interfacial tailored Co2FeAl/\\b{eta}-Ta\n  layers: The Heusler ferromagnetic (FM) compound Co2FeAl interfaced with a high-spin\norbit coupling non-magnetic (NM) layer is a promising candidate for energy\nefficient spin logic circuits. The circuit potential depends on the strength of\nangular momentum transfer across the FM/NM interface; hence, requiring low spin\nmemory loss and high spin-mixing conductance. To highlight this issue, spin\npumping and spin-transfer torque ferromagnetic resonance measurements have been\nperformed on Co_2FeAl/\\beta-Ta heterostructures tailored with Cu interfacial\nlayers. The interface tailored structure yields an enhancement of the effective\nspin-mixing conductance. The interface transparency and spin memory loss\ncorrected values of the spin-mixing conductance, spin Hall angle and spin\ndiffusion length are found to be 3.40 \\pm 0.01 \\times 10^{19} m^{-2}, 0.029 \\pm\n0.003, and 2.3 \\pm 0.5 nm, respectively. Furthermore, a high current modulation\nof the effective damping of around 2.1 % has been achieved at an applied\ncurrent density of 1 \\times 10^9 A/m^2 , which clearly indicates the potential\nof using this heterostructure for energy efficient control in spin devices"
    },
    {
        "anchor": "Dislocations in cubic crystals described by discrete models: Discrete models of dislocations in cubic crystal lattices having one or two\natoms per unit cell are proposed. These models have the standard linear\nanisotropic elasticity as their continuum limit and their main ingredients are\nthe elastic stiffness constants of the material and a dimensionless periodic\nfunction that restores the translation invariance of the crystal and influences\nthe dislocation size. For these models, conservative and damped equations of\nmotion are proposed. In the latter case, the entropy production and\nthermodynamic forces are calculated and fluctuation terms obeying the\nfluctuation-dissipation theorem are added. Numerical simulations illustrate\nstatic perfect screw and 60$^\\circ$ dislocations for GaAs and Si.",
        "positive": "Observation of Anomalous Hall Effect in Noncollinear Antiferromagnetic\n  Mn3Sn Films: Magnetotransport is at the center of the spintronics. Mn3Sn, an\nantiferromagnet that has a noncollinear 120{\\deg} spin order, exhibits large\nanomalous Hall effect (AHE) at room temperature. But such a behavior has been\nremained elusive in Mn3Sn films. Here we report the observation of robust AHE\nup to room temperature in quasi-epitaxial Mn3Sn thin films, prepared by\nmagnetron sputtering. The growth of both (11-20)- and (0001)-oriented Mn3Sn\nfilms provides a unique opportunity for comparing AHE in three different\nmeasurement configurations. When the magnetic field is swept along (0001)\nplane, such as the direction of [01-10] and [2-1-10] the films show\ncomparatively higher anomalous Hall conductivity than its perpendicular\ncounterpart ([0001]), irrespective of their respectively orthogonal current\nalong [0001] or [01-10]. A quite weak ferromagnetic moment of 3 emu/cm^3 is\nobtained in (11-20)-oriented Mn3Sn films, guaranteeing the switching of the\nHall signals with magnetization reversal. Our finding would advance the\nintegration of Mn3Sn in antiferromagnetic spintronics."
    },
    {
        "anchor": "Room temperature cathodoluminescence quenching of Er3+ in AlNOEr: This paper reports a cathodoluminescence (CL) spectroscopic study of\nnanogranular AlNOErx samples with erbiumcontent, x, in the range 0.5--3.6 at%.\nA wide range of erbium concentration was studied with the aim ofunderstanding\nthe concentration quenching of CL. The composition of thin films, deposited by\nradiofrequencyreactive magnetron sputtering, was accurately determined by\nEnergy Dispersive X-ray Spectroscopy (EDS). CLemission was investigated in the\nextended visible spectral range from 350 nm to 850 nm. The critical\nconcentrationof luminescent activator Er3+ above which CL quenching occurs is\n1%; the corresponding criticaldistance between Er3+ ions in AlNOErx is about\n1.0 nm. The quenching mechanism is discussed. We discount anexchange-mediated\ninteraction in favour of a multipole-multipole phonon-assisted interaction.",
        "positive": "Dynamics of a domain wall in a magnetic nanostrip: a toy model: In this report we demonstrate a simple model for the motion of a vortex\ndomain wall in a ferromagnetic strip of submicron width under the influence of\nan external magnetic field. The model exhibits three distinct dynamical\nregimes. In a viscous regime at low fields the wall moves rigidly with a\nvelocity proportional to the field. Above a critical field the motion becomes\nunderdamped as the vortex moves periodically across the strip; these\noscillations are accompanied by a slow drift with a decreasing velocity. At\nstill higher fields the drift velocity starts rising linearly with the field\nagain but with a much lower mobility dv/dH than in the low-field regime. We\ncalculate the relevant quantities and compare them to experimentally observed\nvalues."
    },
    {
        "anchor": "Elastic stability and lattice distortion of refractory high entropy\n  alloys: Refractory high entropy alloys containing elements from the Ti, V and Cr\ncolumns of the periodic table form body centered cubic (BCC) structures.\nElements from the Ti column are noteworthy because they take the BCC structure\nat high temperature but undergo a shear instability and transform to the\nhexagonal (HCP) structure at low temperature. We show that the instability of\nthese elements impacts the properties of the HEAs that contain them. In\nparticular, the shear moduli are greatly reduced, causing increased dynamic\ncontributions to lattice distortion. Relatively large size differences between\nelements of the BCC/HCP column compared with the regular BCC columns create\nadditional static contributions to lattice distortion. These findings are\nsupported by direct evaluation of elastic constants and lattice distortion in\nfour representative HEAs. Comparing moduli of HEAs with those of\ncompositionally averaged pure elements verifies the impact of BCC/HCP elements\nand allows us to estimate the compositions at which the BCC phases become\nelastically unstable, predictions that could be useful in material design.",
        "positive": "Probing discontinuous precipitation in U-Nb: U-Nb's discontinuous precipitation, $\\gamma^{bcc}_{matrix} \\rightarrow\n\\alpha^{orth}_{cellular} + \\gamma'^{bcc}_{cellular}$, is intriguing in the\nsense that it allows formation and growth of the metastable $\\gamma'$ phase\nduring the course of its occurrence. Previous attempts to explain the\nthermodynamic origin of U-Nb's discontinuous precipitation hypothesized that\nthe energy of $\\alpha$ forms an intermediate common tangent with the first\npotential of the double-well energy of $\\gamma$ at the $\\gamma'$ composition.\nWhile this hypothesis is eligible and consistent with the experimental\nobservation of gradual increase in $\\gamma'$ composition at increasing\ntemperature, it is in conflict with recent experiments whose results indicated\na distribution of $\\gamma'$ compositions in the vicinity of 50 at\\%Nb. To shed\nsome light onto this issue, the current work investigates the origin of U-Nb's\ndiscontinuous precipitation in view of fundamental thermodynamics and kinetics,\ntaken from the perspective of phase-field theory. It has been showed that local\nmisfit strain tends to play a crucial role in the formation and growth the\ndiscontinuous precipitation. Depending on the magnitude of strain developed at\ngrain boundaries, either an increasing $\\gamma'$ composition or a random\ndistribution of $\\gamma'$ composition around the equiatomic value with respect\nto increasing temperature could be expected."
    },
    {
        "anchor": "Anomalous Hall effect in YIG$|$Pt bilayers: We measure the ordinary and the anomalous Hall effect in a set of yttrium\niron garnet$|$platinum (YIG$|$Pt) bilayers via magnetization orientation\ndependent magnetoresistance experiments. Our data show that the presence of the\nferrimagnetic insulator YIG leads to an anomalous Hall like signature in Pt,\nsensitive to both Pt thickness and temperature. Interpretation of the\nexperimental findings in terms of the spin Hall anomalous Hall effect indicates\nthat the imaginary part of the spin mixing interface conductance\n$G_{\\mathrm{i}}$ plays a crucial role in YIG$|$Pt bilayers. In particular, our\ndata suggest a sign change in $G_{\\mathrm{i}}$ between $10\\,\\mathrm{K}$ and\n$300\\,\\mathrm{K}$. Additionally, we report a higher order Hall effect, which\nappears in thin Pt films on YIG at low temperatures.",
        "positive": "Electronic noise of warm electrons in semiconductors from\n  first-principles: The ab-initio theory of low-field electronic transport properties such as\ncarrier mobility in semiconductors is well-established. However, an equivalent\ntreatment of electronic fluctuations about a non-equilibrium steady state,\nwhich are readily probed experimentally, remains less explored. Here, we report\na first-principles theory of electronic noise for warm electrons in\nsemiconductors. In contrast with typical numerical methods used for electronic\nnoise, no adjustable parameters are required in the present formalism, with the\nelectronic band structure and scattering rates calculated from\nfirst-principles. We demonstrate the utility of our approach by applying it to\nGaAs and show that spectral features in AC transport properties and noise\noriginate from the disparate time scales of momentum and energy relaxation,\ndespite the dominance of optical phonon scattering. Our formalism enables a\nparameter-free approach to probe the microscopic transport processes that give\nrise to electronic noise in semiconductors."
    },
    {
        "anchor": "Electronic Structure Calculations with the Tran-Blaha Modified\n  Becke-Johnson Density Functional: We report a series of calculations testing the predictions of the Tran-Blaha\nfunctional for the electronic structure and magnetic properties of condensed\nsystems. We find a general improvement in the properties of semiconducting and\ninsulating systems, relative to calculations with standard generalized gradient\napproximations, although this is not always by the same mechanism as other\napproaches such as the quasiparticle GW method. In ZnO the valence bands are\nnarrowed and the band gap is increased to a value in much better agreement with\nexperiment. The Zn $d$ states do not move to higher binding energy as they do\nin LDA+U calculations. The functional is effective for systems with hydride\nanions, where correcting self-interaction errors in the 1$s$ state is\nimportant. Similarly, it correctly opens semiconducting gaps in the alkaline\nearth hexaborides.It correctly stabilizes an antiferromagnetic insulating\nground state for the undoped cuprate parent CaCuO$_2$, but seriously degrades\nthe agreement with experiment for ferromagnetic Gd relative to the standard\nlocal spin density approximation and generalized gradient approximations. This\nis due to positioning of the minority spin $4f$ states at too low an energy.\nConversly, the position of the La $4f$ conduction bands of La$_2$O$_3$ is in\nreasonable accord with experiment as it is with standard functionals. The\nfunctional narrows the Fe $d$ bands of the parent compound LaFeAsO of the iron\nhigh temperature superconductors, while maintaining the high Fe spectral weight\nnear the Fermi energy.",
        "positive": "What did Erwin Mean? The Physics of Information from the Materials\n  Genomics of Aperiodic Crystals and Water to Molecular Information Catalysts\n  and Life: Erwin Schrodinger famously and presciently ascribed the vehicle transmitting\nthe hereditary information underlying life to an `aperiodic crystal'. We\ncompare and contrast this, only later discovered to be stored in the linear\nbiomolecule DNA, with the information bearing, layered quasi-one-dimensional\nmaterials investigated by the emerging field of chaotic crystallography.\nDespite differences in functionality, the same information measures capture\nstructure and novelty in both, suggesting an intimate coherence between the\ninformation character of biotic and abiotic matter---a broadly applicable\nphysics of information. We review layered solids and consider three examples of\nhow information- and computation-theoretic techniques are being applied to\nunderstand their structure. In particular, (i) we review recent efforts to\napply new kinds of information measures to quantify disordered crystals; (ii)\nwe discuss the structure of ice I in information-theoretic terms; and (iii) we\nrecount recent experimental results on tris(bicyclo[2.1.1]hexeno)benzene TBHB),\nshowing how an information-theoretic analysis yields additional insight into\nits structure. We then illustrate a new Second Law of Thermodynamics that\ndescribes information processing in active low-dimensional materials, reviewing\nMaxwell's Demon and a new class of molecular devices that act as information\ncatalysts. Lastly, we conclude by speculating on how these ideas from\ninformational materials science may impact biology."
    },
    {
        "anchor": "Non-vanishing Berry Phase in Chiral Insulators: The binary compounds FeSi, RuSi, and OsSi are chiral insulators crystallizing\nin the space group P2_13 which is cubic. By means of ab initio calculations we\nfind for these compounds a non-vanishing electronic Berry phase, the sign of\nwhich depends on the handedness of the crystal. There is thus the possibility\nthat the Berry phase signals the existence of a macroscopic electric\npolarization due to the electrons. We show that this is indeed so if a small\nexternal magnetic field is applied in the [111]-direction. The electric\npolarization is oscillatory in the magnetic field and possesses a signature\nthat distinguishes the handedness of the crystal. Our findings add to the\ndiscussion of topological classifications of insulators and are significant for\nspintronics applications, and in particular, for a deeper understanding of\nskyrmions in insulators.",
        "positive": "Intense THz source based on BNA organic crystal pumped at Ti:Sapphire\n  wavelength: We report on high energy terahertz pulses by optical rectification (OR) in\nthe organic crystal N-benzyl-2-methyl-4-nitroaniline (BNA) directly pumped by a\nconventional Ti:Sapphire (Ti:Sa) amplifier. The simple scheme provides an\noptical to terahertz conversion efficiency of 0.25% when pumped by a collimated\nlaser pulses with duration of 50 fs and central wavelength of 800nm. The\ngenerated radiation spans frequencies between 0.2 and 3 THz. We measured the\ndamage threshold as well as the dependency of the conversion efficiency on the\npump fluence, pump wavelength, and pulse duration."
    },
    {
        "anchor": "Unique properties of the optical activity in noncentrosymmetric\n  superconductors: sum rule, missing area, and relation with the\n  superconducting Edelstein effect: We present general properties of the optical activity in noncentrosymmetric\nmaterials, including superconductors. We derive a sum rule of the optical\nactivity in general electric states and show that the summation of the spectrum\nis zero, which is independent of the details of electric states. The optical\nactivity has a $\\delta$-function singularity that vanishes in normal phases.\nHowever, the singularity emerges in superconducting phases, corresponding to\nthe Meissner effect in the optical conductivity. The spectrum decreases by the\nsuperconducting gap and has a missing area compared to the normal phase. This\narea is exactly equivalent to the coefficient of the $\\delta$-function\nsingularity due to the universal sum rule. Furthermore, the coefficient is\nexactly equivalent to the superconducting Edelstein effect, which has not yet\nbeen observed in experiments. Thus, this measurement of the missing area offers\nan alternative way to observe the superconducting Edelstein effect.",
        "positive": "Hydrogen accommodation in Zr second phase particles: Implications for H\n  pick-up and hydriding of Zircaloy-2 and Zircaloy-4: Ab-initio computer simulations have been used to predict the energies\nassociated with the accommodation of H atoms at interstitial sites in {\\alpha},\n{\\beta}-Zr and Zr.M intermetallics formed with common alloying additions (M =\nCr, Fe, Ni). Intermetallics that relate to the Zr2(Ni,Fe) second phase\nparticles (SPPs) found in Zircaloy-2 exhibit favourable solution enthalpies for\nH. The intermetallic phases that relate to the Zr(Cr,Fe)2 SPPs, found\npredominantly in Zircaloy-4, do not offer favourable sites for interstitial H.\nIt is proposed that Zr(Cr,Fe)2 particles may act as bridges for the migration\nof H through the oxide layer, whilst the Zr2(Ni,Fe)-type particles will trap\nthe migrating H until these are dissolved or fully oxidised."
    },
    {
        "anchor": "Topological Surface States Protected From Backscattering by Chiral Spin\n  Texture: Topological insulators are a new class of insulators in which a bulk gap for\nelectronic excitations is generated by strong spin orbit coupling. These novel\nmaterials are distinguished from ordinary insulators by the presence of gapless\nmetallic boundary states, akin to the chiral edge modes in quantum Hall\nsystems, but with unconventional spin textures. Recently, experiments and\ntheoretical efforts have provided strong evidence for both two- and\nthree-dimensional topological insulators and their novel edge and surface\nstates in semiconductor quantum well structures and several Bi-based compounds.\nA key characteristic of these spin-textured boundary states is their\ninsensitivity to spin-independent scattering, which protects them from\nbackscattering and localization. These chiral states are potentially useful for\nspin-based electronics, in which long spin coherence is critical, and also for\nquantum computing applications, where topological protection can enable\nfault-tolerant information processing. Here we use a scanning tunneling\nmicroscope (STM) to visualize the gapless surface states of the\nthree-dimensional topological insulator BiSb and to examine their scattering\nbehavior from disorder caused by random alloying in this compound. Combining\nSTM and angle-resolved photoemission spectroscopy, we show that despite strong\natomic scale disorder, backscattering between states of opposite momentum and\nopposite spin is absent. Our observation of spin-selective scattering\ndemonstrates that the chiral nature of these states protects the spin of the\ncarriers; they therefore have the potential to be used for coherent spin\ntransport in spintronic devices.",
        "positive": "Generation-recombination processes via acoustic phonons in a disorded\n  graphene: Generation-recombination interband transitions via acoustic phonons are\nallowed in a disordered graphene because of violation of the energy-momentum\nconservation requirements. The generation-recombination processes are analyzed\nfor the case of scattering by a short-range disorder and the deformation\ninteraction of carriers with in-plane acoustic modes. The\ngeneration-recombination rates were calculated for the cases of intrinsic and\nheavily-doped graphene at room temperature. The transient evolution of\nnonequilibrium carriers is described by the exponential fit dependent on doping\nconditions and disorder level. The characteristic relaxation times are\nestimated to be about 150 - 400 ns for sample with the maximal sheet resistance\n~5 kOhm. This rate is comparable with the generation-recombination processes\ninduced by the thermal radiation."
    },
    {
        "anchor": "Determination of the spin-flip time in ferromagnetic SrRuO3 from\n  time-resolved Kerr measurements: We report time-resolved Kerr effect measurements of magnetization dynamics in\nferromagnetic SrRuO3. We observe that the demagnetization time slows\nsubstantially at temperatures within 15K of the Curie temperature, which is ~\n150K. We analyze the data with a phenomenological model that relates the\ndemagnetization time to the spin flip time. In agreement with our observations\nthe model yields a demagnetization time that is inversely proportional to T-Tc.\nWe also make a direct comparison of the spin flip rate and the Gilbert damping\ncoefficient showing that their ratio very close to kBTc, indicating a common\norigin for these phenomena.",
        "positive": "Structural Changes in Thermoelectric SnSe at High Pressures: The crystal structure of the thermoelectric material tin selenide has been\ninvestigated with angle-dispersive synchrotron x-ray powder diffraction under\nhydrostatic pressure up to 27 GPa. With increasing pressure, a continuous\nevolution of the crystal structure from the GeS type to the higher-symmetry TlI\ntype was observed, with a critical pressure of 10.5(3) GPa. The orthorhombic\nhigh-pressure modification, beta'-SnSe, is closely related to the\npseudo-tetragonal high-temperature modification at ambient pressure. The\nsimilarity between the changes of the crystal structure at elevated\ntemperatures and at high pressures suggests the possibility that strained thin\nfilms of SnSe may provide a route to overcoming the problem of the limited\nthermal stability of beta-SnSe at high temperatures."
    },
    {
        "anchor": "Energy storage properties of ferroelectric nanocomposites: An atomistic effective Hamiltonian technique is used to investigate the\nfinite-temperature energy storage properties of a ferroelectric nanocomposite\nconsisting of an array of BaTiO$_{3}$ nanowires embedded in a SrTiO$_{3}$\nmatrix, for electric field applied along the long axis of the nanowires. We\nfind that the energy density \\textit{versus} temperature curve adopts a\nnonlinear, mostly temperature-independent response when the system exhibits\nphases possessing an out-of-plane polarization and vortices while the energy\ndensity more linearly increases with temperature when the nanocomposite either\nonly possesses vortices (and thus no spontaneous polarization) or is in a\nparaelectric and paratoroidic phase for its equilibrium state. Ultrahigh energy\ndensity up to $\\simeq$140 J/cm$^{3}$ and an ideal 100% efficiency are also\npredicted in this nanocomposite. A phenomenological model, involving a coupling\nbetween polarization and toroidal moment, is further proposed to interpret\nthese energy density results.",
        "positive": "Quantifying Doping Levels in Carbon Nanotubes by Optical Spectroscopy: Controlling doping is essential for a successful integration of semiconductor\nmaterials into device technologies. However, the assessment of doping levels\nand the distribution of charge carriers in carbon nanotubes or other nanoscale\nsemiconductor materials is often either limited to a qualitative attribution of\nbeing 'high' or 'low' or it is entirely absent. Here, we describe efforts\ntoward a quantitative characterization of doping in redox- or electrochemically\ndoped semiconducting carbon nanotubes (s-SWNTs) using VIS-NIR absorption\nspectroscopy. We discuss how carrier densities up to about 0.5 $\\rm nm^{-1}$\ncan be quantified with a sensitivity of roughly one charge per $10^4$ carbon\natoms assuming in-homogeneous or homogeneous carrier distributions."
    },
    {
        "anchor": "Traversing double-well potential energy surfaces: photoinduced\n  concurrent intralayer and interlayer structural transitions in XTe2 (X=Mo, W): Manipulating crystal structure and the corresponding electronic properties in\nquantum materials provides opportunities for the exploration of exotic physics\nand practical applications. Here, by ultrafast electron diffraction, structure\nfactor calculation and TDDFT-MD simulations, we report the photoinduced\nconcurrent intralayer and interlayer structural transitions in the Td and 1T'\nphase of XTe2 (X=Mo, W). Concomitant with the interlayer structural transition\nby shear displacement, the ultrafast suppression of the intralayer Peierls\ndistortion within 0.3 ps is demonstrated and attributed to Mo-Mo (W-W) bond\nstretching. We discuss the modification of multiple quantum electronic states\nassociated with the intralayer and interlayer structural transitions, such as\nthe topological band inversion and the higher-order topological state. The twin\nstructure and the stacking fault in XTe2 are identified by the ultrafast\nstructural response. Our work elucidates the pathway of the photoinduced\nintralayer and interlayer structural transitions in atomic and femtosecond\nspatiotemporal scale. Moreover, the concurrent intralayer and interlayer\nstructural transitions reveals the traversal of all double-well potential\nenergy surfaces (DWPES) by laser excitation in material system, which may be an\nintrinsic mechanism in the field of photoexcitation-driven symmetry\nengineering, beyond the single DWPES transition model and the order-disorder\ntransition model.",
        "positive": "Local charge and spin currents in magnetothermal landscapes: A scannable laser beam is used to generate local thermal gradients in\nmetallic (Co2FeAl) or insulating (Y3Fe5O12) ferromagnetic thin films. We study\nthe resulting local charge and spin currents that arise due to the anomalous\nNernst effect (ANE) and the spin Seebeck effect (SSE), respectively. In the\nlocal ANE experiments, we detect the voltage in the Co2FeAl thin film plane as\na function of the laser spot position and external magnetic field magnitude and\norientation. The local SSE effect is detected in a similar fashion by\nexploiting the inverse spin Hall effect in a Pt layer deposited on top of the\nY3Fe5O12. Our findings establish local thermal spin and charge current\ngeneration as well as spin caloritronic domain imaging."
    },
    {
        "anchor": "Giant magnetic anisotropy at nanoscale: overcoming the superparamagnetic\n  limit: It has been recently observed for palladium and gold nanoparticles, that the\nmagnetic moment at constant applied field does not change with temperature over\nthe range comprised between 5 and 300 K. These samples with size smaller than\n2.5 nm exhibit remanence up to room temperature. The permanent magnetism for so\nsmall samples up to so high temperatures has been explained as due to blocking\nof local magnetic moment by giant magnetic anisotropies. In this report we\nshow, by analysing the anisotropy of thiol capped gold films, that the orbital\nmomentum induced at the surface conduction electrons is crucial to understand\nthe observed giant anisotropy. The orbital motion is driven by localised charge\nand/or spin through spin orbit interaction, that reaches extremely high values\nat the surfaces. The induced orbital moment gives rise to an effective field of\nthe order of 103 T that is responsible of the giant anisotropy.",
        "positive": "Graph Theorem for Chiral Exact Flat Bands at Charge Neutrality: Chiral exact flat bands (FBs) at charge neutrality have attracted much recent\ninterest, presenting an intriguing condensed-matter system to realize exact\nmany-body phenomena, as specifically shown in \"magic angle\" twisted bilayer\ngraphene for superconductivity and triangulene-based superatomic graphene for\nexcitonic condensation. Yet, no generic physical model to realize such FBs has\nbeen developed. Here we present a new mathematical theorem, called bipartite\ndouble cover (BDC) theorem, and prove that the BDC of line-graph (LG) lattices\nhosts at least two chiral exact FBs of opposite chirality, i.e., yin-yang FBs,\ncentered-around/at charge neutrality (E = 0) akin to the \"chiral limit\" of\ntwisted bilayer graphene. We illustrate this theorem by mapping it exactly onto\ntight-binding lattice models of the BDC of LGs of hexagonal lattice for strong\ntopological and of triangular lattice for fragile topological FBs,\nrespectively. Moreover, we use orbital design principle to realize such exotic\nyin-yang FBs in non-BDC lattices to instigate their real material discovery.\nThis work not only enables the search for exact chiral FBs at zero energy\nbeyond moir\\'e heterostructures, but also opens the door to discovering quantum\nsemiconductor features with FB-enabled strongly correlated carriers."
    },
    {
        "anchor": "Thermal Creation of Electron Spin Polarization in n-Type Silicon: Conversion of heat into a spin-current in electron doped silicon can offer a\npromising path for spin-caloritronics. Here we create an electron spin\npolarization in the conduction band of n-type silicon by producing a\ntemperature gradient across a ferromagnetic tunnel contact. The substrate\nheating experiments induce a large spin signal of 95 $\\mu$V, corresponding to\n0.54 meV spin-splitting in the conduction band of n-type silicon by Seebeck\nspin tunneling mechanism. The thermal origin of the spin injection has been\nconfirmed by the quadratic scaling of the spin signal with the Joule heating\ncurrent and linear dependence with the heating power.",
        "positive": "Metal Doping in Topological Insulators- A Key for Tunable Generation of\n  Terahertz: The unique surface edge states make topological insulators a primary focus\namong different applications. In this article, we synthesized a large single\ncrystal of Niobium(Nb)-doped Bi2Se3 topological insulator (TI) with a formula\nNb0.25Bi2Se3. The single crystal has characterized by using various techniques\nsuch as Powder X-ray Diffractometer (PXRD), DC magnetization measurements,\nRaman, and Ultrafast transient absorption spectroscopy (TRUS). There are (00l)\nreflections in the PXRD, and Superconductivity ingrown crystal is evident from\nclearly visible diamagnetic transition at 2.5K in both FC and ZFC measurements.\nThe Raman spectroscopy is used to find the different vibrational modes in the\nsample. Further, the sample is excited by a pump of 1.90 eV, and a kinetic\ndecay profile at 1.38 eV is considered for terahertz analysis. The differential\ndecay profile has different vibrations, and these oscillations have analyzed in\nterms of terahertz. This article not only provides evidence of terahertz\ngeneration in Nb-doped sample along with undoped sample but also show that the\ndopant atom changes the dynamics of charge carriers and thereby the shift in\nthe Terahertz frequency response. In conclusion, a suitable dopant can be used\nas a processor for the tunability of terahertz frequency in TI."
    },
    {
        "anchor": "Analysis of Fracture and Fatigue using Lagrangian Mechanics: Many people are aware of the theory of elastic fracture originated by AA\nGriffith, and although Griffith used the theorem of minimum potential energy\nmost people seem unaware of the broader implications of this theorem. If it is\nset within its classical mechanics roots, it is clear that it is a restricted\nform of a Lagrangian.\n  In advanced texts on fracture cracks are treated as dynamic entities, and the\nrole of stress waves is clearly articulated. However, in most non-advanced\ntexts on fracture and fatigue the role of stress waves are either not included\nor not emphasised, often leading to a possible misunderstanding of the\nfundamentals of fracture.\n  What is done here is to extend Griffiths approach by setting it within the\nconcept of Stationary Action, and introducing a quasi-static stress wave\nunloading model, which connects the energy release mechanism with the stress\nfield. This leads to a definition of a dynamic stress intensity factor, and\nthis model is then applied to fatigue of perfectly elastic and elastic-plastic\nmaterials to include crack tip plasticity.\n  The results for the Griffiths crack and the dynamic case are retrodiction, to\nestablish the validity of the methods used. The extension to fatigue gives\nsignificant new results, which show that for elastic-plastic materials the\ninfluence of the maximum stress in the cycle as a fraction of the yield stress,\ncalled the yield stress ratio, has not been recognised. The new form of the\nfatigue crack growth relationship derived answers many of the long standing\nquestions about the Paris Law.",
        "positive": "Compressive mechanical response of graphene foams and their thermal\n  resistance with copper interfaces: We report compressive mechanical response of graphene foams (GFs) and the\nthermal resistance ($R_{TIM}$) between copper (Cu) and GFs, where GFs were\nprepared by the chemical vapor deposition (CVD) method. We observe that Young's\nmodulus ($E_{GF}$) and compressive strength ($\\sigma_{GF}$) of GFs have a power\nlaw dependence on increasing density ($\\rho_{GF}$) of GFs. The maximum\nefficiency of absorbed energy ($\\eta_{max}$) for all GFs during the compression\nis larger than ~0.39. We also find that a GF with a higher $\\rho_{GF}$ shows a\nlarger $\\eta_{max}$. In addition, we observe that the measured $R_{TIM}$ of\nCu/GFs at room temperature with a contact pressure of 0.25 MP applied increases\nfrom ~50 to ~90 $mm^2K/W$ when $\\rho_{GF}$ increases from 4.7 to 31.9\n$mg/cm^3$."
    },
    {
        "anchor": "Chiral Symmetry of Double-Walled Carbon Nanotubes detected in\n  First-principles Optical Absorption Spectra: The linear polarizability absorption spectra of the double-walled carbon\nnanotubes (DWNTs) have been calculated by using the tight-binding (TB) model\nand sum-over-state (SOS) method, supplemented by the first principles CASTEP\ncalculations. It is found that the chiral symmetries of both outer and inner\ntubes in the DWNTs can always be identified distinctly by the characteristic\npeaks in the absorption spectra of the DWNTs, no matter what kind of the outer\ntube is, offering a powerful experimental tool to measure precisely the chiral\nangle of the inner tube of a DWNT.",
        "positive": "Terahertz radiation imaging of ferroelectric domain topology in\n  room-temperature organic supramolecular ferroelectrics: We demonstrate a new method to detect ferroelectric domains in inside and\nsurface regions of organic ferroelectrics by mapping out two orthogonally\npolarized terahertz waves radiated from the crystal upon the irradiation of\nnear-infrared femtosecond laser pulses. We used polarization dependence of the\neffective depths radiating the terahertz waves, which originate from the\noptical anisotropy in the terahertz frequency region. This allows us to\ndistinguish ferroelectric domains in the inside and surface regions of the\ncrystals. We applied this method to a room-temperature organic supramolecular\nferroelectric crystal, 1:1 salt of 5,5'-dimethyl-2,2'-bipyridine and deuterated\niodanilic acid. A single domain covering almost all the area of an as-grown\ncrystal ($\\sim$600 $\\mu$m $\\times$ 800 $\\mu$m) is discerned in the inside\nregion, while complicated multi-domain in size of $\\sim$ 200 $\\mu$m is observed\nin the surface region. By applying external electric field along the 2c-b axis\n(ferroelectric polarization direction), the polarization switching proceeds\nwith successive propagations of uncharged (neutral) and quasi-one-dimensional\n180$^\\circ$ domain walls (DWs) along the b-axis ($\\perp$ 2c-b axis). This\nresults in the formation of another uncharged and two-dimensional 180$\\circ$ DW\nparallel to the (100) plane, which covers all the area of the crystal. We\ndiscuss the usefulness of the present terahertz radiation imaging technique and\nferroelectric DW dynamics in terms of anisotropic stacking of hydrogen-bonded\nchains."
    },
    {
        "anchor": "Pb-doped p-type Bi$_2$Se$_3$ thin films via interfacial engineering: Due to high density of native defects, the prototypical topological insulator\n(TI), Bi$_2$Se$_3$, is naturally n-type. Although Bi$_2$Se$_3$ can be converted\ninto p-type by substituting 2+ ions for Bi, only light elements such as Ca have\nbeen so far effective as the compensation dopant. Considering that strong\nspin-orbit coupling (SOC) is essential for the topological surface states, a\nlight element is undesirable as a dopant, because it weakens the strength of\nSOC. In this sense, Pb, which is the heaviest 2+ ion, located right next to Bi\nin the periodic table, is the most ideal p-type dopant for Bi$_2$Se$_3$.\nHowever, Pb-doping has so far failed to achieve p-type Bi$_2$Se$_3$ not only in\nthin films but also in bulk crystals. Here, by utilizing an interface\nengineering scheme, we have achieved the first Pb-doped p-type Bi$_2$Se$_3$\nthin films. Furthermore, at heavy Pb-doping, the mobility turns out to be\nsubstantially higher than that of Ca-doped samples, indicating that Pb is a\nless disruptive dopant than Ca. With this SOC-preserving counter-doping scheme,\nit is now possible to fabricate Bi$_2$Se$_3$ samples with tunable Fermi levels\nwithout compromising their topological properties.",
        "positive": "Phonon dispersion of MoS$_2$: Transition metal dichalcogenides like MoS$_2$, MoSe$_2$, WS$_2$, and WSe$_2$\nhave attracted enormous interest during recent years. They are van-der-Waals\ncrystals with highly anisotropic properties, which allows exfoliation of\nindividual layers. Their remarkable physical properties make them promising for\napplications in optoelectronic, spintronic, and valleytronic devices. Phonons\nare fundamental to many of the underlying physical processes, like carrier and\nspin relaxation or exciton dynamics. However, experimental data of the complete\nphonon dispersion relations in these materials is missing. Here we present the\nphonon dispersion of bulk MoS$_2$ in the high-symmetry directions of the\nBrillouin zone, determined by inelastic X-ray scattering. Our results underline\nthe two-dimensional nature of MoS$_2$. Supported by first-principles\ncalculations, we determine the phonon displacement patterns, symmetry\nproperties, and scattering intensities. The results will be the basis for\nfuture experimental and theoretical work regarding electron-phonon\ninteractions, intervalley scattering, as well as phonons in related 2D\nmaterials."
    },
    {
        "anchor": "Interface-mediated thermomechanical effects during high velocity impact\n  between monocrystalline surfaces: High velocity impact between crystalline surfaces is important for a range of\nmaterial phenomena, yet a fundamental understanding of the effect of surface\nstructure, energetics and kinetics on the underlying thermo-mechanical response\nremains elusive. Here, we employ non-equilibrium molecular dynamics (NEMD)\nsimulations to describe the nanoscale dynamics of the high velocity impact\nbetween commensurate and incommensurate monocrystalline (001) copper surfaces.\nFor impact velocities in the range 100-1200 m/s, the kinetic energy dissipation\ninvolves nucleation and emission of dislocation loops from defective sites\nwithin the rapidly forming interface, well below the bulk single-crystal yield\npoint. At higher velocities, adiabatic dissipation occurs via\nplasticity-induced heating as the interface structurally melts following the\nimpact. The adhesive strength of the reformed interface is controlled by the\nformation and nucleation of dislocations and point defects as they modify the\ninterfacial energy relative to the deformed bulk. As confirmation, the excess\ninterface energy decreases monotonically with increasing impact velocity. The\nrelative crystal orientation of the surfaces equally important; the grain\nboundaries formed following incommensurate impact exhibit higher impact\nresistance, with smaller defect densities and interfacial enthalpies,\nsuggesting an enhanced ability of the grain boundaries to absorb the\nnon-equilibrium damage and therefore facilitate particle bonding. Our study\nhighlights the key role played by the atomic-scale surface structure in\ndetermining the impact resistance and adhesion of crystalline surfaces.",
        "positive": "Fast Free Energy Calculations for Unstable High-Temperature Phases: We present a fast and accurate method to calculate vibrational properties for\nmechanically unstable high temperature phases that suffer from imaginary\nfrequencies at zero temperature. The method is based on standard\nfinite-difference calculations with optimized large displacements and is\nsignificantly more efficient than other methods. We demonstrate its application\nfor calculation of phonon dispersion relations, free energies, phase transition\ntemperatures, and vacancy formation energies for body-centered cubic\nhigh-temperature phases of Ti, Zr, and Hf."
    },
    {
        "anchor": "Dependence of the electronic structure of self-assembled InGaAs/GaAs\n  quantum dots on height and composition: While electronic and spectroscopic properties of self-assembled\nIn_{1-x}Ga_{x}As/GaAs dots depend on their shape, height and alloy\ncompositions, these characteristics are often not known accurately from\nexperiment. This creates a difficulty in comparing measured electronic and\nspectroscopic properties with calculated ones. Since simplified theoretical\nmodels (effective mass, k.p, parabolic models) do not fully convey the effects\nof shape, size and composition on the electronic and spectroscopic properties,\nwe offer to bridge the gap by providing accurately calculated results as a\nfunction of the dot height and composition. Prominent results are the\nfollowing. (i) Regardless of height and composition, the electron levels form\nshells of nearly degenerate states. In contrast, the hole levels form shells\nonly in flat dots and near the highest hole level (HOMO). (ii) In alloy dots,\nthe electrons' ``s-p'' splitting depends weakly on height, while the ``p-p''\nsplitting depends non-monotonically. In non-alloyed InAs/GaAs dots, both these\nsplittings depend weakly on height. For holes in alloy dots, the ``s-p''\nsplitting decreases with increasing height, whereas the ``p-p'' splitting\nremains nearly unchaged. Shallow, non-alloyed dots have a ``s-p'' splitting of\nnearly the same magnitude, whereas the ``p-p'' splitting is larger. (iii) As\nheight increases, the ``s'' and ``p'' character of the wavefunction of the HOMO\nbecomes mixed, and so does the heavy- and light-hole character. (iv) In alloy\ndots, low-lying hole states are localized inside the dot. Remarkably, in\nnon-alloyed InAs/GaAs dots these states become localized at the interface as\nheight increases. This localization is driven by the biaxial strain present in\nthe nanostructure.",
        "positive": "Ultrathin Washcoat and Very Low Loading Monolithic Catalyst with\n  Outstanding Activity and Stability in Dry Reforming of Methane: A Ni/CeO2/ZrO2 catalyst with improved redox properties has been washcoated\nonto a honeycomb cordierite monolith in the form of a nonconventional\nalumina-catalyst layer, just a few nanometer thick. In spite of the very low\nactive phase loading, the monolith depicts outstanding performance in dry\nreforming of methane, both in terms of activity, with values reaching the\nthermodynamic limit already at 750 C, even under extreme weight Hourly Space\nVelocities (WHSV 115-346 L.g-1.h-1), as well as in terms of stability during\nprolonged time on stream (TOS 24-48 h)."
    },
    {
        "anchor": "Auxetic properties of polycrystals: Young's and shear moduli and Poisson's ratio of polycrystalline solids\nconsisting of 2D quadratic and 3D cubic randomly oriented grains of the same\nsize and shape is studied. Considered polycrystals are initially unstrained. It\nis shown that for such polycrystals the division of the mechanical stability\nregions into areas of various auxeticity properties is different than for\nmonocrystalline solids. In particular the regions of complete auxeticity\nenlarge.",
        "positive": "Local Geometry of the Fermi Surface and the Cyclotron Resonance in\n  Metals in a Normal Magnetic Field: In this paper we present a detailed theoretical analysis of the cyclotron\nresonance in metals in the magnetic field directed along a normal to the\nsurface of a sample. We show that this resonance occurs due to local geometry\nof the Fermi surface of a metal. When the Fermi surface (FS) includes segments\nwhere its curvature turns zero or diverges, this could give rise to resonance\nfeatures in the frequency/magnetic field dependence of the surface impedance or\nits derivative with respect to the field. Otherwise the resonance is scarcely\ndetectable unlike the well-known cyclotron resonance in a parallel magnetic\nfield. The proposed theory agrees with experimantal results concerning both\nconvenient and organic metals."
    },
    {
        "anchor": "Evaluation of hyperelastic models for unidirectional short fibre\n  reinforced materials using a representative volume element with refined\n  boundary conditions: The simulation of a short fibre reinforced structure by means of the FEM\nrequires the knowledge of the material behaviour at every Gauss point. In order\nto obtain such information, a representative volume element (RVE) containing\nunidirectional short fibres is analysed in the presented work. The findings are\nused to assess the applicability of several hyperelastic models describing\ntransversal isotropic materials under consideration of large deformations. As\nthe RVE's average response represents the homogenised behaviour at a\nmacroscopic material point, the material models' parameters can be identified\nby fitting them to stress-strain curves obtained from simulations with the RVE.\nThe application of periodic boundary conditions to the RVE in tensorial form\nenables a simple access to consider tilted fibres and catch the anisotropy\ninduced by the fibres. The comparison of the calibrated material model with the\nRVE allows the assessment of the material model's applicability and quality.\nBoth the modelling and the calculations are carried out with the commercial FEM\nsoftware ABAQUS.",
        "positive": "Modeling 1D structures on semiconductor surfaces: Synergy of theory and\n  experiment: Atomic scale nanowires attract enormous interest in a wide range of fields.\nOn the one hand, due to their quasi-one-dimensional nature, they can act as a\nexperimental testbed for exotic physics: Peierls instability, charge density\nwaves, and Luttinger liquid behavior. On the other hand, due to their small\nsize, they are of interest for future device applications in the\nmicro-electronics industry, but also for applications regarding molecular\nelectronics. This versatile nature makes them interesting systems to produce\nand study, but their size and growth conditions push both experimental\nproduction and theoretical modeling to their limits. In this review, modeling\nof atomic scale nanowires on semiconductor surfaces is discussed focusing on\nthe interplay between theory and experiment. The current state of modeling\nefforts on Pt- and Au-induced nanowires on Ge(001) is presented, indicating\ntheir similarities and differences. Recently discovered nanowire systems (Ir,\nCo, Sr) on the Ge(001) surface are also touched upon. The importance of\nscanning tunneling microscopy as a tool for direct comparison of theoretical\nand experimental data is shown, as is the power of density functional theory as\nan atomistic simulation approach. It becomes clear that complementary strengths\nof theoretical and experimental investigations are required for successful\nmodeling of the atomistic nanowires, due to their complexity."
    },
    {
        "anchor": "Miniature Magnetic Nano islands in a Morphotropic Cobaltite Matrix: High-density magnetic memories are key components in spintronics, quantum\ncomputing, and energy-efficient electronics. Reduced dimensionality and\nmagnetic domain stability at the nanoscale are essential for the\nminiaturization of magnetic storage units. Yet, inducing magnetic order, and\nselectively tuning spin-orbital coupling at specific locations have remained\nchallenging. Here we demonstrate the construction of switchable magnetic\nnano-islands in a nonmagnetic matrix based on cobaltite homo-structures. The\nmagnetic and electronic states are laterally modified by epitaxial strain,\nwhich is regionally controlled by freestanding membranes. Atomically sharp\ngrain boundaries isolate the crosstalk between magnetically distinct regions.\nThe minimal size of magnetic nano-islands reaches 35 nm in diameter, enabling\nan areal density of 400 Gbit per inch square. Besides providing an ideal\nplatform for precisely controlled read and write schemes, this methodology can\nenable scalable and patterned memories on silicon and flexible substrates for\nvarious applications.",
        "positive": "Magnetoelectric interactions in polycrystalline multiferroic\n  antiferromagnets CuFe(1-x)RhxO2 (x=0.00 and x=0.05): Magnetoelectric coupling in the polycrystalline antiferromagnets\nCuFe0.95Rh0.05O2 and CuFeO2 has been investigated. For both samples, electric\npolarization was observed in the absence of an applied external magnetic field\ndemonstrating that for multiferroic research ceramics are worth to be studied.\nThe observed magnetodielectric effect for CuFe0.95Rh0.05O2 in the electrically\npolar phase supports the existence of a noncollinear antiferromagnetic state.\nInterestingly, the electric polarization of this sample can be suppressed by a\nmagnetic field. The temperature dependence of the relative magnitude of the\nmagnetodielectric effect shows a discontinuity, clearly indicating different\nmechanisms of the magnetodielectric couplings in polar and paraelectric\nantiferromagnetic states."
    },
    {
        "anchor": "Rigid-layer Raman-active modes in $N$-layer Transition Metal\n  Dichalcogenides: interlayer force constants and hyperspectral Raman imaging: We report a comparative study of rigid layer Raman-active modes in $N$-layer\ntransition metal dichalcogenides. Trigonal prismatic (2Hc, such as MoSe$_2$,\nMoTe$_2$, WS$_2$, WSe$_2$) and distorted octahedral (1T', such as ReS$_2$ and\nReSe$_2$) phases are considered. The Raman-active in-plane interlayer shear\nmodes and out-of-plane interlayer breathing modes appear as well-defined\nfeatures with wavenumbers in the range 0-40~cm$^{-1}$. These rigid layer modes\nare well-described by an elementary linear chain model from which the\ninterlayer force constants are readily extracted. Remarkably, these force\nconstants are all found to be of the same order of magnitude. Finally, we show\nthat the prominent interlayer shear and breathing mode features allow\nhigh-precision hyperspectral Raman imaging of $N-$layer domains within a given\ntransition metal dichalcogenide flake.",
        "positive": "Role of CDW fluctuations on the spectral function in a metallic CDW\n  system: Angle-resolved photoemission spectroscopy of ZrTe3 has been performed from\nroom temperature(T) down to 6 K (across Tcdw = 63K) to study the\ncharge-density-wave (CDW) fluctuation effects in a metallic CDW compound having\nFermi surface (FS) sheets with differing dimensionality. While spectra on the\n3-dimensional(D) FS show typical Fermi-Dirac function-like T-dependence, those\nalong the quasi 1-D FS show formation of a pseudogap, starting at a much higher\nT than Tcdw. Simultaneously, a van-Hove singularity consisting of the quasi 1D\nFS intersecting the 3D FS shows increase of coherence. This demonstrates the\nrole of CDW fluctuations on the spectral function, and relation to the\ndimensionality of the states, in a metallic CDW system."
    },
    {
        "anchor": "Origin of spin-glass behavior of Zn_1-xMn_xO: ac susceptibility has been studied for polycrystalline Zn$_{1-x}$Mn$_x$O.\nStoichiometric samples demonstrate Curie-Weiss behavior, which indicates mostly\nantiferromagnetic interactions. Magnetic susceptibility can be described by a\ndiluted Heisenberg magnet model developed for semimagnetic semiconductors.\nHigh-pressure oxygen annealing induces spin-glass like behavior in\nZn$_{1-x}$Mn$_x$O by precipitation of ZnMnO$_3$ in the paramagnetic matrix.",
        "positive": "Considerations for utilizing sodium chloride in epitaxial molybdenum\n  disulfide: The utilization of alkali salts, such as NaCl and KI, have enabled the\nsuccessful growth of large single domain and fully coalesced polycrystalline\ntwo-dimensional (2D) transition metal dichalcogenide layers. However, the\nimpact of alkali salts on photonic and electronic properties are not fully\nestablished. In this work, we report alkali-free epitaxy of MoS2 on sapphire\nand benchmark the properties against alkali-assisted growth of MoS2. This study\ndemonstrates that although NaCl can dramatically increase the domain size of\nmonolayer MoS2 by 20 times, it can also induce strong optical and electronic\nheterogeneities in as-grown large-scale films. This work elucidates that\nutilization of NaCl can lead to variation in growth rates, loss of epitaxy, and\na high density of nanoscale MoS2 particles (4/{\\mu}m2). Such phenomena suggest\nthat alkali atoms play an important role in Mo and S adatom mobility and\nstrongly influence the 2D/sapphire interface during growth. Compared to\nalkali-free synthesis under the same growth conditions, MoS2 growth assisted by\nNaCl results in >1% tensile strain in as-grown domains, which reduces\nphotoluminescence by ~20x and degrades transistor performance."
    },
    {
        "anchor": "Quantum transport evidence of Weyl fermions in an epitaxial\n  ferromagnetic oxide: Magnetic Weyl fermions, which occur in magnets, have novel transport\nphenomena related to pairs of Weyl nodes, and they are, of both, scientific and\ntechnological interest, with the potential for use in high-performance\nelectronics, spintronics and quantum computing. Although magnetic Weyl fermions\nhave been predicted to exist in various oxides, evidence for their existence in\noxide materials remains elusive. SrRuO3, a 4d ferromagnetic metal often used as\nan epitaxial conducting layer in oxide heterostructures, provides a promising\nopportunity to seek for the existence of magnetic Weyl fermions. Advanced oxide\nthin film preparation techniques, driven by machine learning technologies, may\nallow access to such topological matter. Here we show direct quantum transport\nevidence of magnetic Weyl fermions in an epitaxial ferromagnetic oxide SrRuO3:\nunsaturated linear positive magnetoresistance (MR), chiral-anomaly-induced\nnegative MR, Pi Berry phase accumulated along cyclotron orbits, light cyclotron\nmasses and high quantum mobility of about 10000 cm2/Vs. We employed\nmachine-learning-assisted molecular beam epitaxy (MBE) to synthesize SrRuO3\nfilms whose quality is sufficiently high to probe their intrinsic quantum\ntransport properties. We also clarified the disorder dependence of the\ntransport of the magnetic Weyl fermions, and provided a brand-new diagram for\nthe Weyl transport, which gives a clear guideline for accessing the\ntopologically nontrivial transport phenomena. Our results establish SrRuO3 as a\nmagnetic Weyl semimetal and topological oxide electronics as a new research\nfield.",
        "positive": "Controlled Smooth Edge Formation of Graphene Nanoribbons: We report energy estimated to dissociate a C-C bond of a graphene sheet to\nform nanoribbons of armchair and zigzag configurations using first principles\ncalculations. For the ground state energy calculations, the configurations\nconsidered are with spin, and without spin polarization. It is observed that\nthe energy required to dissociate a C-C bond of a graphene sheet to form zigzag\nconfiguration is higher than that of armchair configuration for both spin\npolarized state, as well as non-spin polarized state. Therefore, formation of\nsmooth edged graphene nanoribbons along the crystallographic directions might\nbe engineered by a control over energy."
    },
    {
        "anchor": "Spin dependent recombination based magnetic resonance spectroscopy of\n  bismuth donor spins in silicon at low magnetic fields: Low-field (6-110 mT) magnetic resonance of bismuth (Bi) donors in silicon has\nbeen observed by monitoring the change in photoconductivity induced by spin\ndependent recombination. The spectra at various resonance frequencies show\nsignal intensity distributions drastically different from that observed in\nconventional electron paramagnetic resonance, attributed to different\nrecombination rates for the forty possible combinations of spin states of a\npair of a Bi donor and a paramagnetic recombination center. An excellent\ntunability of Bi excitation energy for the future coupling with superconducting\nflux qubits at low fields has been demonstrated.",
        "positive": "Classical nucleation theory in the phase-field crystal model: A full understanding of polycrystalline materials requires studying the\nprocess of nucleation, a thermally activated phase transition that typically\noccurs at atomistic scales. The numerical modeling of this process is\nproblematic for traditional numerical techniques: commonly used phase-field\nmethods' resolution does not extend to the atomic scales at which nucleation\ntakes places, while atomistic methods such as molecular dynamics are incapable\nof scaling to the mesoscale regime where late-stage growth and structure\nformation takes place following earlier nucleation. Consequently, it is of\ninterest to examine nucleation in the more recently proposed phase-field\ncrystal (PFC) model, which attempts to bridge the atomic and mesoscale regimes\nin microstructure simulations. In this work, we numerically calculate\nhomogeneous liquid-to-solid nucleation rates and incubation times in the\nsimplest version of the PFC model, for various parameter choices. We show that\nthe model naturally exhibits qualitative agreement with the predictions of\nclassical nucleation theory (CNT) despite a lack of some explicit atomistic\nfeatures presumed in CNT. We also examine the early appearance of lattice\nstructure in nucleating grains, finding disagreement with some basic\nassumptions of CNT. We then argue that a quantitatively correct nucleation\ntheory for the PFC model would require extending CNT to a multi-variable\ntheory."
    },
    {
        "anchor": "Short-range spin order and frustrated magnetism in Mn2InSbO6 and\n  Mn2ScSbO6: The complex metal oxides Mn2ASbO6 (A=In, Sc) with a corundum-related\nstructure A3BO6 have been prepared as polycrystalline powders by a solid state\nreaction route. The crystal structure and magnetic properties have been\ninvestigated using a combination of X-ray and neutron powder diffraction,\nelectron microscopy, calorimetric and magnetic measurements. At room\ntemperature these compounds adopt a trigonal structure, space group R-3 with a\n= 8.9313(1) {\\AA}, c = 10.7071(2) {\\AA} (for In) and a = 8.8836(1) {\\AA}, c =\n10.6168(2) {\\AA} (for Sc) which persists down to 1.6 K. The Mn and A cations\nwere found to be randomly distributed over the A-sites. The overall behavior of\nthe magnetization of Mn2InSbO6 and Mn2ScSbO6 is quite similar. In spite of the\nrelatively large amount of Mn ions on the A-site, only short-ranged magnetism\nis observed. Neutron diffraction patterns of Mn2InSbO6 showed no evidence of a\nlong-range magnetic ordering at 1.6 K, instead only a weak diffuse magnetic\npeak was observed at low temperatures. The factors governing the observed\nstructural and magnetic properties of Mn2ASbO6 are discussed and compared with\nthose of other Mn-containing complex metal oxides with a corundum-related\nstructure. The influence of the A-cation sublattice on magnetic properties is\nalso considered.",
        "positive": "Interband Tunneling for Hole Injection in III-Nitride Ultra-violet\n  Emitters: Ultra-violet emitters have several applications in the areas of sensing,\nwater purification, and data storage. While the III-Nitride semiconductor\nsystem has the band gap region necessary for ultraviolet emission, achieving\nefficient ultraviolet solid state emitters remains a challenge due to the low\np-type conductivity and high contact resistance in wide band gap AlGaN-based\nultra-violet light emitters. In this work, we show that efficient interband\ntunneling can be used for non-equilibrium injection of holes into ultraviolet\nemitters. Polarization-engineered tunnel junctions were used to enhance\ntunneling probability by several orders of magnitude over a PN homojunction,\nleading to highly efficient tunnel injection of holes to ultraviolet light\nemitters. This demonstration of efficient interband tunneling introduces a new\nparadigm for design of ultra-violet light emitting diodes and diode lasers, and\nenables higher efficiency and lower cost ultra-violet emitters."
    },
    {
        "anchor": "Absence of Morphotropic Phase Boundary Effects in BiFeO3-PbTiO3 Thin\n  Films Grown via a Chemical Multilayer Deposition Method: Here, we report the unusual behaviour shown by the (BiFeO3)1-x-(PbTiO3)x\n(BF-xPT) films prepared using a multilayer deposition approach by chemical\nsolution deposition method. Thin film samples of various compositions were\nprepared by depositing several bilayers of BF and PT precursors by varying the\nBF or PT layer thicknesses. X-ray diffraction showed that final samples of all\ncompositions show mixing of the two compounds resulting in a single phase\nmixture, also confirmed by transmission electron microscopy. In contrast to\nbulk equilibrium compositions, our samples show a monoclinic (MA type)\nstructure suggesting disappearance of morphotropic phase boundary (MPB) about x\n= 0.30 as observed in the bulk. This is accompanied by the lack of any\nenhancement of remnant polarization at MPB as shown by the ferroelectric\nmeasurements. Magnetic measurements show that the magnetization of the samples\nincreases with increasing BF content. Significant magnetization of the samples\nindicates melting of spin spirals in the BF-xPT arising from random\ndistribution of iron atoms across the film. Absence of Fe2+ ions in the films\nwas corroborated by X-ray photoelectron spectroscopy measurements. The results\nillustrate that used thin film processing methodology significantly changes the\nstructural evolution in contrast to predictions from the equilibrium phase\ndiagram as well as modify the functional characteristics of BP-xPT system\ndramatically.",
        "positive": "Large Hall electron mobilities in head-to-head BaTiO$_3$-domain walls: Strongly charged head-to-head (H2H) domain walls (DWs) that are purposely\nengineered along the [110] crystallographic orientation into ferroelectric\nBaTiO$_3$ single crystals have been proposed as novel 2-dimensional electron\ngases (2DEGs) due to their significant domain wall conductivity (DWC). Here, we\nquantify these 2DEG properties through dedicated Hall-transport measurements in\nvan-der-Pauw 4-point geometry at room temperature, finding the electron\nmobility to reach around 400~cm$^2$(Vs)$^{-1}$, while the 2-dimensional charge\ndensity amounts to ~7$\\times$10$^3$cm$^{-2}$. We underline the necessity to\ntake account of thermal and geometrical-misalignment offset voltages by\nevaluating the Hall resistance under magnetic-field sweeps, since otherwise\ndramatic errors of several hundred percent in the derived mobility and charge\ndensity values can occur. Apart from the specific characterization of the\nconducting BaTiO$_3$ DW, we propose the method as an easy and fast way to\nquantitatively characterize ferroic conducting DWs, complementary to previously\nproposed scanning-probe-based Hall-potential analyses."
    },
    {
        "anchor": "Even-odd oscillation of conductance of 5{\\it d} metal atomic nanowires: The electron-transport properties of single-row monoatomic nanowires made of\n5$d$ elements are examined by first-principles calculations based on the\ndensity functional theory. We found that oscillation patterns with a period\nlonger than two-atom length are dominant in the conductance of Ir and Pt\nmonoatomic nanowires, although the transmission of the $s$-$d_{z^2}$ channel\nstill exhibits even-odd oscillatory behavior. When the nanowires are deformed\ninto zigzag configurations from the straight configuration, the oscillation\nbehavior of the patterns with long periods changes and the oscillations\neventually disappear. On the other hand, the even-odd oscillatory behavior of\nthe $s$-$d_{z^2}$ channel still survives even in the deformed nanowire. The\neven-odd oscillation in the conductance of Ir and Pt nanowires is interpreted\nto be due to the low sensitivity of the oscillation of the $s$-$d_{z^2}$\nchannel to the spatial deformation of the nanowires.",
        "positive": "Emergence of Spin Ice freezing in Dy$_2$Ti$_{1.8}$Mn$_{0.2}$O$_7$: We herein present the spin freezing dynamics of stuffed polycrystalline\ncompound Dy$_2$Ti$_{1.8}$Mn$_{0.2}$O$_7$. In Dy$_2$Ti$_2$O$_7$, spin freezes\nwith ice-like spin relaxations at a temperature around 3 K (T$_i$) along with\nanother spin freezing at a temperature around 0.7 K (T\\textless T$_i$). These\nrelaxations can be observed prominently with an application of varying DC\nmagnetic field bias and applied AC-field. We show here that with fractional\ninclusion of Mn at the Ti site in Dy$_2$Ti$_2$O$_7$, there is a significant\nshift in these temperatures. In Dy$_2$Ti$_{1.8}$Mn$_{0.2}$O$_7$ the T$_i$\nshifts to a higher temperature around 5 K and freezing belonging to T\\textless\nT$_i$ shifts to 2.5 K without any application of external DC Bias and/or\nAC-field. The inclusion of Mn at Ti site also enhances the ferromagnetic\ninteraction for Dy$_2$Ti$_{1.8}$Mn$_{0.2}$O$_7$ as compared to\nDy$_2$Ti$_2$O$_7$. Arrhenius fit of freezing temperature with frequency for\nDy$_2$Ti$_{1.8}$Mn$_{0.2}$O$_7$ shows that these spin relaxations at T$_i$ and\nT\\textless T$_i$ are thermally induced. Low-temperature structural change in\nlattice parameters and crystal field phonon coupling has been studied using\nsynchrotron x-ray diffraction. Debye-Gruineisen analysis of\ntemperature-dependent lattice volume shows the emergence of crystal field\nphonon coupling at a much higher temperature (70 K) in\nDy$_2$Ti$_{1.8}$Mn$_{0.2}$O$_7$ in contrast to 40 K in Dy$_2$Ti$_2$O$_7$. These\nfindings make Dy$_2$Ti$_{1.8}$Mn$_{0.2}$O$_7$ a suitable system to explore the\napplication of the spin ice phenomenon at a workable temperature."
    },
    {
        "anchor": "Optimal design of low-frequency band gaps in anti-tetrachiral lattice\n  meta-materials: The elastic wave propagation is investigated in the beam lattice material\ncharacterized by a square periodic cell with anti-tetrachiral microstructure.\nWith reference to the Floquet-Bloch spectrum, focus is made on the band\nstructure enrichments and modifications which can be achieved by equipping the\ncellular microstructure with tunable local resonators. By virtue of its\ncomposite mechanical nature, the so-built inertial meta-material gains enhanced\ncapacities of passive frequency-band filtering. Indeed the number, placement\nand properties of the inertial resonators can be designed to open, shift and\nenlarge the band gaps between one or more pairs of consecutive branches in the\nfrequency spectrum. In order to improve the meta-material performance, a\nnonlinear optimization problem is formulated. The maximum of the largest band\ngap amplitudes in the low-frequency range is selected as suited objective\nfunction. Proper inequality constraints are introduced to restrict the optimal\nsolutions within a compact set of mechanical and geometric parameters,\nincluding only physically realistic properties of both the lattice and\nresonators. The optimization problems related to full and partial band gaps are\nsolved independently, by means of a globally convergent version of the\nnumerical method of moving asymptotes, combined with a quasi-Monte Carlo\nmulti-start technique. The optimal solutions are discussed and compared from\nthe qualitative and quantitative viewpoints, bringing to light the limits and\npotential of the meta-material performance. The clearest trends emerging from\nthe numerical analyses are pointed out and interpreted from the physical\nviewpoint. Finally, some specific recommendations about the microstructural\ndesign of the meta-material are synthesized.",
        "positive": "ZnO-Based Polariton Laser Operating at Room Temperature: From Excitonic\n  to Photonic Condensate: A laser threshold is determined by the gain condition, which has been\nprogressively reduced by the use of heterostructures and of quantum\nconfinement. The polariton laser is the ultimate step of this evolution:\ncoherent emission is obtained from the spontaneous decay of an\nexciton-polariton condensate, without the achievement of any gain condition.\nZnO, with its unique excitonic properties, is the best choice for a\nblue/UV-emitting polariton laser device. We report on the fabrication of a new\nfamily of fully hybrid microcavities that combine the best-quality ZnO material\navailable (bulk substrate) and two dielectric distributed Bragg reflectors,\ndemonstrating large quality factors (>2500) and Rabi splittings (~200 meV). Low\nthreshold polariton lasing is achieved between 4 and 300 K and for excitonic\nfractions ranging between 12% and 96 %. A phase diagram highlighting the role\nof LO phonon-assisted relaxation in this polar semiconductor is established,\nand a remarkable switching between polariton modes is demonstrated."
    },
    {
        "anchor": "Sequential pulsed laser deposition of homoepitaxial SrTiO$_3$ thin films: Control of thin film stoichiometry is of primary relevance to achieve desired\nfunctionality. Pulsed laser deposition ablating from binary-oxide targets\n(sequential deposition) can be applied to precisely control the film\ncomposition, offsetting the importance of growth conditions on the film\nstoichiometry. In this work, we demonstrate that the cation stoichiometry of\nSrTiO$_3$ thin films can be finely tuned by sequential deposition from SrO and\nTiO$_2$ targets. Homoepitaxial SrTiO$_3$ films were deposited at different\nsubstrate temperatures and Ti/Sr pulse ratios, allowing the establishment of a\ngrowth window for stoichiometric SrTiO$_3$. The growth kinetics and nucleation\nprocesses were studied by reflection high-energy electron diffraction and\natomic force microscopy, providing information about the growth mode and the\ndegree of off-stoichiometry. At the optimal (stoichiometric) growth conditions,\nfilms exhibit atomically flat surfaces, whereas off-stoichiometry is\naccommodated by crystal defects, 3D islands and/or surface precipitates\ndepending on the substrate temperature and the excess cation. This technique\nopens the way to precisely control stoichiometry and doping of oxide thin\nfilms.",
        "positive": "Theory of field emission: A serious barrier impedes the comparison between the theoretical prediction\nand the experimental observation in field emission because there is no way to\nmeasure the emission area. We introduce three dimensionless variables\n$\\mathcal{R}_{J}$, $\\mathcal{S}$ and $\\mathcal{D}$ to construct a formulation\nfor connecting directly the theoretical variables and experimental data without\nmeasuring the emission area. Based on this formulation we can analyze that the\nbehaviors of $\\mathcal{R}_{J}$ $\\mathcal{S}$ and $\\mathcal{D}$ with the\nvoltages between the anode and the emitter to reveals the characteristics of\ncurrent-voltage (I-V) curve and detect the physical properties of emitters.\nThis formulation provides a way to understand the fundamental physics of I-V\ncurve in field emission and to set up a map between the physical properties of\nemitters and the experimental I-V curve."
    },
    {
        "anchor": "Tunneling magnetoresistance in (La,Pr,Ca)MnO3 nanobridges: The manganite (La,Pr,Ca)MnO3 is well known for its micrometer scale phase\nseparation into coexisting ferromagnetic metallic and antiferromagnetic\ninsulating (AFI) regions. Fabricating bridges with widths smaller than the\nphase separation length scale has allowed us to probe the magnetic properties\nof individual phase separated regions. We observe tunneling magnetoresistance\nacross naturally occurring AFI tunnel barriers separating adjacent\nferromagnetic regions spanning the width of the bridges. Further, near the\nCurie temperature, a magnetic field induced metal-to-insulator transition among\na discrete number of regions within the narrow bridges gives rise to abrupt and\ncolossal low-field magnetoresistance steps at well defined switching fields.",
        "positive": "Decoupling minimal surface metamaterial properties through\n  multi-material hyperbolic tilings: Rapid advances in additive manufacturing over the past decade have kindled\nwidespread interest in the rational design of metamaterials with unique\nproperties. However, many applications require multi-physics metamaterials,\nwhere multiple properties are simultaneously optimized. This is challenging,\nsince different properties, such as mechanical and mass transport properties,\ntypically impose competing requirements on the nano-/micro-/meso-architecture\nof metamaterials. Here, we propose a parametric metamaterial design strategy\nthat enables independent tuning of the effective permeability and elastic\nproperties. We apply hyperbolic tiling theory to devise simple templates based\non which triply periodic minimal surfaces (TPMS) are partitioned into hard and\nsoft regions. Through computational analyses, we demonstrate how the decoration\nof hard, soft, and void phases within the TPMS substantially enhances their\npermeability-elasticity property space and offers high tunability in the\nelastic properties and anisotropy, at constant permeability. We also show that\nthis permeability-elasticity balance is well captured using simple scaling\nlaws. We then proceed to demonstrate the proposed concept through\nmulti-material additive manufacturing of representative specimens. Our\napproach, which is generalizable to other designs, offers a route towards\nmulti-physics metamaterials that need to simultaneously carry a load and enable\nmass transport, such as load-bearing heat exchangers or architected\ntissue-substituting meta-biomaterials."
    },
    {
        "anchor": "First-Principles Bulk-Layer Model for Dielectric and Piezoelectric\n  Responses in Superlattices: In the first-principles bulk-layer model the superlattice structure and\npolarization are determined by first-principles computation of the bulk\nresponses of the constituents to the electrical and mechanical boundary\nconditions in an insulating superlattice. In this work the model is extended to\npredict functional properties, specifically dielectric permittivity and\npiezoelectric response. A detailed comparison between the bulk-layer model and\nfull first-principles calculations for three sets of perovskite oxide\nsuperlattices, PbTiO$_3$/BaTiO$_3$, BaTiO$_3$/SrTiO$_3$ and\nPbTiO$_3$/SrTiO$_3$, is presented. The bulk-layer model is shown to give an\nexcellent first approximation to these important functional properties, and to\nallow for the identification and investigation of additional physics, including\ninterface reconstruction and finite size effects. Technical issues in the\ngeneration of the necessary data for constituent compounds are addressed. These\nresults form the foundation for a powerful data-driven method to facilitate\ndiscovery and design of superlattice systems with enhanced and tunable\npolarization, dielectric permittivity, and piezoelectric response.",
        "positive": "Large longitudinal magnetoresistance of multivalley systems: The longitudinal magnetoresistance (MR) is assumed to be hardly realized as\nthe Lorentz force does not work on electrons when the magnetic field is\nparallel to the current. However, in some cases, longitudinal MR becomes large,\nwhich exceeds the transverse MR. To solve this problem, we have investigated\nthe longitudinal MR considering multivalley contributions based on the\nclassical MR theory. We have showed that the large longitudinal MR is caused by\noff-diagonal components of a mobility tensor. Our theoretical results agree\nwith the experiments of large longitudinal MR in IV-VI semiconductors,\nespecially in PbTe, for a wide range of temperatures, except for linear MR at\nlow temperatures."
    },
    {
        "anchor": "Drastic changes of electronic structure and crystal chemistry upon\n  oxidation of SnII2TiO4E2 into SnIV2TiO6: an ab initio study: From DFT based calculations establishing energy-volume equations of state and\nelectron localization mapping, the electronic structure and crystal chemistry\nchanges from Sn2TiO4 to Sn2TiO6 by oxidation are rationalized; the key effect\nbeing the destabilization of divalent tin SnII towards tetravalent state SnIV\nleading to rutile Sn2TiO6 as experimentally observed. The subsequent electronic\nstructure change is highlighted in the relative change of the electronic band\ngap which increases from ~1eV up to 2.2 eV and the 1.5 times increase of the\nbulk modulus assigned to the change from covalently SnII based compound to the\nmore ionic SnIV one. Such trends are also confronted with the relevant\nproperties of black SnIIO characterized by very small band gap.",
        "positive": "Saturation of electrical resistivity in metals at large temperatures: We present a microscopic model for systems showing resistivity saturation. An\nessentially exact quantum Monte-Carlo calculation demonstrates that the model\ndescribes saturation. We give a simple explanation for saturation, using charge\nconservation and considering the limit where thermally excited phonons have\ndestroyed the periodicity. Crucial model features are phonons coupling to the\nhopping matrix elements and a unit cell with several atoms. We demonstrate the\ndifference to a model of alkali-doped C60 with coupling to the level positions,\nfor which there is no saturation."
    },
    {
        "anchor": "Design of ternary alkaline-earth metal Sn(II) oxides with potential good\n  p-type conductivity: Oxides with good p-type conductivity have been long sought after to achieve\nhigh performance all-oxide optoelectronic devices. Divalent Sn(II) based oxides\nare promising candidates because of their rather dispersive upper valence bands\ncaused by the Sn-5s/O-2p anti-bonding hybridization. There are so far few known\nSn(II) oxides being p-type conductive suitable for device applications. Here,\nwe present via first-principles global optimization structure searches a\nmaterial design study for a hitherto unexplored Sn(II)-based system, ternary\nalkaline-earth metal Sn(II) oxides in the stoichiometry of MSn2O3 (M = Mg, Ca,\nSr, Ba). We identify two stable compounds of SrSn2O3 and BaSn2O3, which can be\nstabilized by Sn-rich conditions in phase stability diagrams. Their structures\nfollow the Zintl behaviour and consist of basic structural motifs of SnO3\ntetrahedra. Unexpectedly they show distinct electronic properties with band\ngaps ranging from 1.90 (BaSn2O3) to 3.15 (SrSn2O3) eV, and hole effective\nmasses ranging from 0.87 (BaSn2O3) to above 6.0 (SrSn2O3) m0. Further\nexploration of metastable phases indicates a wide tunability of electronic\nproperties controlled by the details of the bonding between the basic\nstructural motifs. This suggests further exploration of alkaline-earth metal\nSn(II) oxides for potential applications requiring good p-type conductivity\nsuch as transparent conductors and photovoltaic absorbers.",
        "positive": "Tunable electrical transport through annealed monolayers of monodisperse\n  cobalt-platinum nanoparticles: We synthesized monodisperse cobalt-platinum nanoparticles\nCo(0.14-0.22)Pt(0.86-0.78) of 9 nm in diameter by colloidal chemistry methods\nand deposited them by the Langmuir-Blodgett technique as highly ordered\nmonolayers onto substrates with e-beam defined gold electrodes. Upon annealing\nwe observe an increase of conductivity over more than 4 orders of magnitude. A\nfirst attempt of explanation of this unanticipated effect, a nanoparticle\ndisplacement, could not be confirmed for annealing temperatures below 400C. A\nsecond approach, a carbonization of the ligands, however, could be confirmed by\nRaman spectroscopy. The simple thermal treatment allows tuning essential\nproperties of electronic devices based on nanoparticles by the manipulation of\nthe interparticle coupling, namely the electrical conductivity, the Coulomb\nblockade characteristic, and the activation energy of the system."
    },
    {
        "anchor": "Coherent Heteroepitaxy of Bi2Se3 on GaAs (111)B: We report the heteroepitaxy of single crystal thin films of Bi2Se3 on the\n(111)B surface of GaAs by molecular beam epitaxy. We find that Bi2Se3 grows\nhighly c-axis oriented, with an atomically sharp interface with the GaAs\nsubstrate. By optimizing the growth of a very thin GaAs buffer layer before\ngrowing the Bi2Se3, we demonstrate the growth of thin films with atomically\nflat terraces over hundreds of nanometers. Initial time-resolved Kerr rotation\nmeasurements herald opportunities for probing coherent spin dynamics at the\ninterface between a candidate topological insulator and a large class of\nGaAs-based heterostructures.",
        "positive": "Predicting and interpreting oxide glass properties by machine learning\n  using large datasets: With the advent of powerful computer simulation techniques, it is time to\nmove from the widely used knowledge-guided empirical methods to approaches\ndriven by data science, mainly machine learning algorithms. We investigated the\npredictive performance of three machine learning algorithms for six different\nglass properties. For such, we used an extensive dataset of about 150,000 oxide\nglasses, which was segmented into smaller datasets for each property\ninvestigated. Using the decision tree induction, k-nearest neighbors, and\nrandom forest algorithms, selected from a previous study of six algorithms, we\ninduced predictive models for glass transition temperature, liquidus\ntemperature, elastic modulus, thermal expansion coefficient, refractive index,\nand Abbe number. Moreover, each model was induced with default and tuned\nhyperparameter values. We demonstrate that, apart from the elastic modulus\n(which had the smallest training dataset), the induced predictive models for\nthe other five properties yield a comparable uncertainty to the usual data\nspread. However, for glasses with extremely low or high values of these\nproperties, the prediction uncertainty is significantly higher. Finally, as\nexpected, glasses containing chemical elements that are poorly represented in\nthe training set yielded higher prediction errors. The method developed here\ncalls attention to the success and possible pitfalls of machine learning\nalgorithms. The analysis of the SHAP values indicated the key elements that\nincrease or decrease the value of the modeled properties. It also estimated the\nmaximum possible increase or decrease. Insights gained by this analysis can\nhelp empirical compositional tuning and computer-aided inverse design of glass\nformulations."
    },
    {
        "anchor": "Ab-Initio calculations of binding energy of In and Ga adatoms on three\n  GaAs(111)A surface reconstructions: Calculations of the potential energy surface for tracer Ga and In adatoms\nabove three GaAs (111)A surface reconstructions are presented in order to\nunderstand the growth conditions required to form axial heterostructures in\nGaAs/InGaAs nano-pillars. In all calculations the Ga adatom has a stronger bond\nenergy to the surface than the In adatom. The diffusion barriers for Ga adatoms\nare 140meV larger than for In adatoms on the Ga vacancy surface, but they are\ncomparable on the As trimer surface. Also the binding energy for an In adatom\nis closer to that of a Ga adatom on the As trimer surface. We conclude that the\nAs trimer surface is preferable for adsorption of In and thus for selective\nformation of hetero-interfaces on (111) facets. This work helps explain the\nrecent successful formation of axial GaAs/InGaAs hetero-interfaces in catalyst\nfree nano-pillars.",
        "positive": "Bulk and Surface Magnetization of Co atoms in Rutile\n  Ti_[1-x]Co_xO_[2-delta] Thin Films Revealed by X-Ray Magnetic Circular\n  Dichroism: We have studied magnetism in Ti_[1-x]Co_xO_[2-\\delta] thin films with various\nx and \\delta by soft x-ray magnetic circular dichroism (XMCD) measurements at\nthe Co L_[2,3] absorption edges. The estimated ferromagnetic moment by XMCD was\n0.15-0.24 \\mu\\beta/Co in the surface, while in the bulk it was 0.82-2.25\n\\mu\\beta/Co, which is in the same range as the saturation magnetization of\n1.0-1.5 \\mu\\beta/Co. Theseresults suggest that the intrinsic origin of the\nerromagnetism. The smaller moment of Co atom at surface is an indication of a\nmagnetically dead layer of a few nm thick at the surface of the thin films."
    },
    {
        "anchor": "RF amplification property of the MgO-based magnetic tunnel junction\n  using field-induced ferromagnetic resonance: The radio-frequency (RF) voltage amplification property of a tunnel\nmagnetoresistance device driven by an RF external-magnetic-field-induced\nferromagnetic resonance was studied. The proposed device consists of a magnetic\ntunnel junction (MTJ) and an electrically isolated coplanar waveguide. The\ninput RF voltage applied to the waveguide can excite the resonant dynamics in\nthe free layer magnetization, leading to the generation of an output RF voltage\nunder a DC bias current. The dependences of the RF voltage gain on the static\nexternal magnetic field strength and angle were systematically investigated.\nThe design principles for the enhancement of the gain factor are also\ndiscussed.",
        "positive": "Depth Dependence of the Structural Phase Transition of SrTiO_3 Studied\n  with \u03b2-NMR and Grazing Incidence X-ray Diffraction: We present an investigation of the near-surface tetragonal phase transition\nin SrTiO3, using the complementary techniques of beta-detected nuclear magnetic\nresonance and grazing-incidence X-ray diffraction. The results show a clear\ndepth dependence of the phase transition on scales of a few microns. The\nmeasurements support a model in which there are tetragonal domains forming in\nthe sample at temperatures much higher than the bulk phase transition\ntemperature. Moreover, we find that these domains tend to form at higher\ntemperatures preferentially near the free surface of the crystal. The details\nof the tetragonal domain formation and their depth/lateral dependencies are\ndiscussed."
    },
    {
        "anchor": "Transport in organic semiconductors in large electric fields: From\n  thermal activation to field emission: Understanding charge transport in organic semiconductors in large electric\nfields is relevant to many applications. We present transport measurements in\norganic field-effect transistors based on poly(3-hexylthiophene) and\n6,13-bis(triisopropyl-silylethynyl) pentacene with short channels, from room\ntemperature down to 4.2 K. Near 300 K transport in both systems is well\ndescribed by thermally assisted hopping with Poole-Frenkel-like enhancement of\nthe mobility. At low temperatures and large gate voltages, transport in both\nmaterials becomes nearly temperature independent, crossing over into\nfield-driven tunneling. These data, particularly in TIPS-pentacene, show that\ngreat caution must be exercised when considering more exotic (e.g.,\nTomonaga-Luttinger Liquid) interpretations of transport.",
        "positive": "Electric quadrupole second harmonic generation revealing dual magnetic\n  orders in a magnetic Weyl semimetal: Broken symmetries and electronic topology are nicely manifested together in\nthe second order nonlinear optical responses from topologically nontrivial\nmaterials. While second order nonlinear optical effects from the electric\ndipole (ED) contribution have been extensively explored in polar Weyl\nsemimetals (WSMs) with broken spatial inversion (SI) symmetry, they are rarely\nstudied in centrosymmetric magnetic WSMs with broken time reversal (TR)\nsymmetry due to complete suppression of the ED contribution. Here, we report\nexperimental demonstration of optical second harmonic generation (SHG) in a\nmagnetic WSM Co$_{3}$Sn$_{2}$S$_{2}$ from the electric quadrupole (EQ)\ncontribution. By tracking the temperature dependence of the rotation anisotropy\n(RA) of SHG, we capture two magnetic phase transitions, with both the SHG\nintensity increasing and its RA pattern rotating at $T_{C,1}$=175K and\n$T_{C,2}$=120K subsequently. The fitted critical exponents for the SHG\nintensity and RA orientation near $T_{C,1}$ and $T_{C,2}$ suggest that the\nmagnetic phase at $T_{C,1}$ is a 3D Ising-type out-of-plane ferromagnetism\nwhile the other at $T_{C,2}$ is a 3D XY-type all-in-all-out in-plane\nantiferromagnetism. Our results show the success of detection and exploration\nof EQ SHG in a centrosymmetric magnetic WSM, and hence open the pathway towards\nthe future investigation of its tie to the band topology."
    },
    {
        "anchor": "Vertex corrections in localized and extended systems: Within many-body perturbation theory we apply vertex corrections to various\nclosed-shell atoms and to jellium, using a local approximation for the vertex\nconsistent with starting the many-body perturbation theory from a DFT-LDA\nGreen's function. The vertex appears in two places -- in the screened Coulomb\ninteraction, W, and in the self-energy, \\Sigma -- and we obtain a systematic\ndiscrimination of these two effects by turning the vertex in \\Sigma on and off.\nWe also make comparisons to standard GW results within the usual random-phase\napproximation (RPA), which omits the vertex from both. When a vertex is\nincluded for closed-shell atoms, both ground-state and excited-state properties\ndemonstrate only limited improvements over standard GW. For jellium we observe\nmarked improvement in the quasiparticle band width when the vertex is included\nonly in W, whereas turning on the vertex in \\Sigma leads to an unphysical\nquasiparticle dispersion and work function. A simple analysis suggests why\nimplementation of the vertex only in W is a valid way to improve quasiparticle\nenergy calculations, while the vertex in \\Sigma is unphysical, and points the\nway to development of improved vertices for ab initio electronic structure\ncalculations.",
        "positive": "Spin-density functional study of the organic polymer\n  dimethylaminopyrrole: A realization of the organic periodic Anderson model: While the periodic Anderson model (PAM) has been recognized as a good model\nfor various heavy f-electron systems, here we design a purely organic polymer\nwhose low-energy physics can be captured by PAM. By means of the spin density\nfunctional calculation, we show that polymer of dimethylaminopyrrole is a\ncandidate, where its ground state can indeed be magnetic depending on the\ndoping. We discuss the factors favoring ferromagnetic ground state."
    },
    {
        "anchor": "Valence band and core-level analysis of highly luminescent ZnO\n  nanocrystals for designing ultrafast optical sensors: Highly luminescent ZnO:Na nanocrystals of size ~2 nm were synthesized using a\nimproved sol-lyophilization process. The surface analysis such as survey scan,\ncore-level and valence band spectra of ZnO:Na nanocrystals were studied using\nx-ray photoelectron spectroscopy (XPS) to establish the presence of Na+ ions.\nThe observed increase in band gap from 3.30 (bulk) to 4.16 eV (nano), is\nattributed to the quantum confinement of the motion of electron and holes in\nall three directions. The photoluminescence and decay measurements have\ncomplemented and supported our study to design an efficient and ultrafast\nresponsive optical sensing device.",
        "positive": "Construction and evaluation of an ultrahigh-vacuum-compatible sputter\n  deposition source: A sputter deposition source for use in ultrahigh vacuum (UHV) is described\nand some properties of the source are analyzed. The operating principle is\nbased on the design developed by Mayr et al. [Rev. Sci. Instrum. 84, 094103\n(2013)], where electrons emitted from a filament ionize argon gas, and the\nAr$^+$ ions are accelerated to the target. In contrast to the original design,\ntwo grids are used to direct a large fraction of the Ar$^+$ ions to the target,\nand the source has a housing cooled by liquid nitrogen to reduce\ncontaminations. The source has been used for deposition of zirconium, a\nmaterial that is difficult to evaporate in standard UHV evaporators. At an Ar\npressure of $9\\times 10^{-6}$ mbar in the UHV chamber and moderate emission\ncurrent, a highly reproducible deposition rate of $\\approx 1$ monolayer in 250\ns was achieved at the substrate (at a distance of $\\approx 50$ mm from the\ntarget). Higher deposition rates are easily possible. X-ray photoelectron\nspectroscopy shows a high purity of the deposited films. Depending on the grid\nvoltages, the substrate gets mildly sputtered by Ar$^+$ ions; in addition, the\nsubstrate is also reached by electrons from the negatively biased sputter\ntarget."
    },
    {
        "anchor": "Unexplored photoluminescence from bulk and mechanically exfoliated few\n  layers of Bi2Te3: We report the exotic photoluminescence (PL) behaviour of 3D topological\ninsulator Bi2Te3 single crystals grown by customized self-flux method and\nmechanically exfoliated few layers (18 plus minus 2 nm)/thin flakes obtained by\nstandard scotch tape method from as grown Bi2Te3 crystals.The experimental PL\nstudies on bulk single crystal and mechanically exfoliated few layers of Bi2Te3\nevidenced a broad red emission in the visible region. These findings are in\ngood agreement with our theoretical results obtained using the ab initio\ndensity functional theory framework.",
        "positive": "Acoustic Phonon Lifetimes Limit Thermal Transport in Methylammonium Lead\n  Iodide: Hybrid organic-inorganic perovskites (HOIPs) have become an important class\nof semiconductors for solar cells and other optoelectronic applications.\nElectron-phonon coupling plays a critical role in all optoelectronic devices,\nand although the lattice dynamics and phonon frequencies of HOIPs have been\nwell studied, little attention has been given to phonon lifetimes. We report\nthe first high-precision measurements of acoustic phonon lifetimes in the\nhybrid perovskite methylammonium lead iodide (MAPI), using inelastic neutron\nspectroscopy to provide high energy resolution and fully deuterated single\ncrystals to reduce incoherent scattering from hydrogen. Our measurements reveal\nextremely short lifetimes on the order of picoseconds, corresponding to\nnanometer mean free paths and demonstrating that acoustic phonons are unable to\ndissipate heat efficiently. Lattice-dynamics calculations using ab-initio\nthird-order perturbation theory indicate that the short lifetimes stem from\nstrong three-phonon interactions and a high density of low-energy optical\nphonon modes related to the degrees of freedom of the organic cation. Such\nshort lifetimes have significant implications for electron-phonon coupling in\nMAPI and other HOIPs, with direct impacts on optoelectronic devices both in the\ncooling of hot carriers and in the transport and recombination of band edge\ncarriers. These findings illustrate a fundamental difference between HOIPs and\nconventional photovoltaic semiconductors and demonstrate the importance of\nunderstanding lattice dynamics in the effort to develop metal halide perovskite\noptoelectronic devices."
    },
    {
        "anchor": "Low-loss resonant modes in deterministically aperiodic nanopillar\n  waveguides: Quasiperiodic Fibonacci-like and fractal Cantor-like single- and multiple-row\nnanopillar waveguides are investigated theoretically employing the finite\ndifference time domain (FDTD) method. It is shown that resonant modes of the\nFibonacci and Cantor waveguides can have a Q-factor comparable with that of a\npoint-defect resonator embedded in a periodic nanopillar waveguide, while the\nradiation is preferably emitted into the waveguide direction, thus improving\ncoupling to an unstructured dielectric waveguide located along the structure\naxis. This is especially so when the dielectric waveguide introduces a small\nperturbation in the aperiodic structure, breaking the structure symmetry while\nstaying well apart from the main localization area of the resonant mode. The\nhigh Q-factor and increased coupling with external dielectric waveguide suggest\nusing the proposed deterministically aperiodic nanopillar waveguides in\nphotonic integrated circuits.",
        "positive": "Learning the right channel in multimodal imaging: automated experiment\n  in Piezoresponse Force Microscopy: We report the development and experimental implementation of the automated\nexperiment workflows for the identification of the best predictive channel for\na phenomenon of interest in spectroscopic measurements. The approach is based\non the combination of ensembled deep kernel learning for probabilistic\npredictions and a basic reinforcement learning policy for channel selection. It\nallows the identification of which of the available observational channels,\nsampled sequentially, are most predictive of selected behaviors, and hence have\nthe strongest correlations. We implement this approach for multimodal imaging\nin Piezoresponse Force Microscopy (PFM), with the behaviors of interest\nmanifesting in piezoresponse spectroscopy. We illustrate the best predictive\nchannel for polarization-voltage hysteresis loop and frequency-voltage\nhysteresis loop areas is amplitude in the model samples. The same workflow and\ncode are universal and applicable for any multimodal imaging and local\ncharacterization methods."
    },
    {
        "anchor": "Spin currents in the Rashba model in the presence of non-uniform fields: Spin currents in a two dimensional electron gas with Rashba-type spin orbit\ncoupling are derived from a spin connection. Using a functional integral\nmethod, we recover the result derived by Sinova {\\em et al.}$[\n\\mathrm{Phys.Rev. Lett.\n  92, 126603 (2004)}]$ for a uniform electric field and in the absence of\nimpurities. We extend this result to inhomogeneous electric and magnetic\nfields. We find that non-uniform magnetic fields can give rise to spin currents\nthat are independent of the Rashba coupling and hence are less susceptible to\nimpurities than in the case of uniform electric fields.",
        "positive": "An ab-initio theory for the temperature dependence of magnetic\n  anisotropy: We present a first-principles theory of the variation of magnetic anisotropy,\nK, with temperature, T, in metallic ferromagnets. It is based on relativistic\nelectronic structure theory and calculation of magnetic torque. Thermally\ninduced `local moment' magnetic fluctuations are described within the\nrelativistic generalisation of the `disordered local moment' (R-DLM) theory\nfrom which the T dependence of the magnetisation, m, is found. We apply the\ntheory to a uniaxial magnetic material with tetragonal crystal symmetry,\nL1_0-ordered FePd, and find its uniaxial K consistent with a magnetic easy axis\nperpendicular to the Fe/Pd layers for all m and proportional to m squared for a\nbroad range of values of m. This is the same trend that we have previously\nfound in L1_0-ordered FePt and which agrees with experiment. This account,\nhowever, differs qualitatively from that extracted from a single ion anisotropy\nmodel. We also study the magnetically soft cubic magnet, the Fe(50)Pt(50) solid\nsolution, and find that its small magnetic anisotropy constant K_1 rapidly\ndiminishes from 8 micro-eV to zero. K evolves from being proportional to the\nseventh power of m at low T to the fourth power near the Curie temperature."
    },
    {
        "anchor": "Electromodulation of the Magnetoresistance in Diluted Magnetic\n  Semiconductors Based Heterostructures: We study the properties of heterostructures formed by two layers of diluted\nmagnetic semiconductor separated by a nonmagnetic semiconductor layer. We find\nthat there is a RKKY-type exchange coupling between the magnetic layers that\noscilles between ferromagnetic and antiferromagnetic as a function of the\ndifferent parameters in the problem. The different transport properties of\nthese phases make that this heterostructure presents strong magnetoresistive\neffects. The coupling can be also modified by an electric field. We propose\nthat it is possible to alter dramatically the electrical resistance of the\nheterostructure by applying an electric field. Our results indicate that in a\nsingle gated sample the magnetoresistance could be modulated by with an\nelectrical bias voltage.",
        "positive": "Dynamical pinning of domain wall in magnetic nanowire induced by Walker\n  breakdown: Transmission probability of a domain wall through a magnetic nanowire is\ninvestigated as a function of the external magnetic field. Very intriguing\nphenomenon is found that the transmission probability shows a significant drop\nafter exceeding the threshold driving field, which contradicts our intuition\nthat a domain wall is more mobile in the higher magnetic field. The\nmicromagnetics simulation reveals that the domain wall motion in the wire with\nfinite roughness causes the dynamical pinning due to the Walker breakdown,\nwhich semi-quantitatively explains our experimental results."
    },
    {
        "anchor": "Mapping the B,T phase diagram of frustrated metamagnet CuFeO2: The magnetic phase diagram of CuFeO2 as a function of applied magnetic field\nand temperature is thoroughly explored and expanded, both for magnetic fields\napplied parallel and perpendicular to the material's c-axis. Pulsed field\nmagnetization measurements extend the typical magnetic staircase of CuFeO2 at\nvarious temperatures, demonstrating the persistence of the recently discovered\nhigh field metamagnetic transition up to Tn2 ~ 11 K in both field\nconfigurations. An extension of the previously introduced phenomenological spin\nmodel used to describe the high field magnetization process (Phys. Rev. B, 80,\n012406 (2009)) is applied to each of the consecutive low-field commensurate\nspin structures, yielding a semi-quantitative simulation and intuitive\ndescription of the entire experimental magnetization process in both relevant\nfield directions with a single set of parameters.",
        "positive": "Dipolar interactions and anisotropic magnetoresistance in metallic\n  granular systems: We revisit the theory of magnetoresistance for a system of nanoscopic\nmagnetic granules in metallic matrix. Using a simple model for the spin\ndependent perturbation potential of the granules, we solve Boltzmann equation\nfor the spin dependent components of the non equilibrium electronic\ndistribution function. For typical values of the geometric parameters in\ngranular systems, we find a peculiar structure of the distribution function of\nconduction electrons, which is at variance with the two-current model of\nconduction in inhomogeneous systems. Our treatment explicitly includes the\neffects of dipolar correlations yielding a magnetoresistance ratio which\ncontains, in addition to the term proportional to the square of uniform\nmagnetization (< {\\boldsymbol \\mu} >), a weak anisotropic contribution\ndepending on the angle between electric and magnetic fields, and arising from\nthe anisotropic character of dipolar interactions."
    },
    {
        "anchor": "Thermomechanical model for NiTi-based shape memory alloys covering\n  macroscopic localization of martensitic transformation: The work presents a thermomechanical model for polycrystalline NiTi-based\nshape memory alloys developed within the framework of generalized standard\nsolids, which is able to cover loading-mode dependent localization of the\nmartensitic transformation. The key point is the introduction of a novel\naustenite-martensite interaction term responsible for strain-softening of the\nmaterial. Mathematical properties of the model are analyzed and a suitable\nregularization and a time-discrete approximation for numerical implementation\nto the finite-element method are proposed. Model performance is illustrated on\ntwo numerical simulations: tension of a superelastic NiTi ribbon and bending of\na superelastic NiTi tube.",
        "positive": "Electrically Tunable Quantum Spin Hall State in Topological Crystalline\n  Insulator Thin films: Based on a combination of $k \\cdot p$ theory, band topology analysis and\nelectronic structure calculations, we predict the (111) thin films of the SnTe\nclass of three-dimensional (3D) topological crystalline insulators realize the\nquantum spin Hall phase in a wide range of thickness. The nontrivial topology\noriginates from the inter-surface coupling of the topological surface states of\nTCI in the 3D limit. The inter-surface coupling changes sign and gives rise to\ntopological phase transitions as a function of film thickness. Furthermore,\nthis coupling can be strongly affected by an external electric field, hence the\nquantum spin Hall phase can be effectively tuned under experimentally\naccessible the electric field. Our results show that (111) thin films of\nSnTe-class TCI can be an ideal platform to realize the novel applications of\nquantum spin Hall insulators."
    },
    {
        "anchor": "Thermoelectric properties of marcasite-type compounds MSb$_2$ (M = Ta,\n  Nb): A combined experimental and computational study: Here, we investigate the thermoelectric properties of the marcasite-type\ncompounds MSb$_2$ (M = Ta, Nb) in the temperature range of 310-730 K. These\ncompounds were synthesized by a solid-state reaction followed by the spark\nplasma sintering process. The Rietveld refinement method confirms the\nmonoclinic phase with space group C2/m for both compounds. The observed values\nof Seebeck coefficients exhibit non-monotonic behaviour in the studied\ntemperature range, with the maximum magnitude of -14.4 and -22.7 $\\mu$V\nK$^{-1}$ for TaSb$_2$ and NbSb$_2$, respectively at ~444 K. The negative sign\nof S in the full temperature window signifies the n-type behaviour of these\ncompounds. Both electrical and thermal conductivities show an increasing trend\nwith temperature. The experimentally observed thermoelectric properties are\nunderstood through the first-principles DFT and Boltzmann transport equation. A\npseudogap in the density of states around the Fermi level characterizes the\nsemimetallic behaviour of these compounds. The multi-band electron and hole\npockets were found to be mainly responsible for the temperature dependence of\ntransport properties. The experimental power factors are found to be ~0.09 and\n~0.42 mW m$^{-1}$ K$^{-2}$ at 310 K for TaSb2 and NbSb2, respectively. From the\nDFT-based calculations, the maximum possible power factors for p-type\nconduction are predicted as ~1.14 and ~1.74 mW m$^{-1}$ K$^{-2}$, while these\nvalues are found to be ~1.16 and ~1.80 mW m$^{-1}$ K$^{-2}$ for n-type TaSb$_2$\nand NbSb$_2$, respectively at 300 K with the corresponding doping\nconcentrations. The present study suggests that the combined DFT and Boltzmann\ntransport theory are found to be reasonably good at explaining the experimental\ntransport properties, and moderate power factors are predicted.",
        "positive": "Kramers' revenge: The combination of space inversion and time reversal symmetries result in\ndoubly-degenerate Bloch states with opposite spin. Many lattices with these\nsymmetries can be constructed by combining a noncentrosymmetric potential\n(lacking this degeneracy) with its inverted copy. Using simple models, we\nunravel the evolution of local spin-splitting during this process of inversion\nsymmetry restoration, in the presence of spin-orbit interaction and sublattice\ncoupling. Importantly, through an analysis of quantum mechanical commutativity,\nwe examine the difficulty of identifying states that are simultaneously\nspatially segregated and spin polarized. We also explain how experimental\nprobes (such as angle-resolved photoemission spectroscopy, or ARPES) of `hidden\nspin polarization' in layered materials are susceptible to unrelated spin\nsplitting intrinsically induced by broken inversion symmetry at the surface."
    },
    {
        "anchor": "Intrinsic auxeticity and mechanical anisotropy of Si9C15 siligraphene: The graphene-like two-dimensional (2D) silicon carbide or siligraphene has\nattracted remarkable attentions, owing to its fascinating physical properties.\nNevertheless, the first high-quality siligraphene, i.e., monolayer Si9C15 was\nsynthesised very recently, which exhibits an excellent semiconducting\nbehaviour. In this work, we investigate the mechanical properties of Si9C15\nsiligraphene by using atomistic simulations including density functional theory\n(DFT) calculations and molecular dynamics (MD) simulations. Both methods\nconfirm the existence of intrinsic negative Poisson's ratios in Si9C15\nsiligraphene, which, as illustrated by MD simulations, is attributed to the\ntension-induced de-wrinkling behaviours of its intrinsic rippled configuration.\nDifferent de-wrinkling behaviours are observed in different directions of\nSi9C15 siligraphene, which result in the anisotropy of its auxetic property.\nThe fracture property of Si9C15 siligraphene is similarly anisotropic, but\nrelatively large fracture strains are observed in different orientations,\nindicating the stretchability of Si9C15 siligraphene. The stretchability\ntogether with the strain-sensitive bandgap of Si9C15 siligraphene observed in\nDFT calculations indicates the effectiveness of strain engineering in\nmodulating its electronic property. The combination of unique auxetic property,\nexcellent mechanical property and tunable electronic property may render Si9C15\nsiligraphene a novel 2D material with multifunctional applications.",
        "positive": "Strong Electronic Polarization of the C60 Fullerene by the\n  Imidazolium-Based Ionic Liquids: Accurate Insights from Born-Oppenheimer\n  Molecular Dynamics Simulations: Fullerenes are known to be polarizable due to the strained carbon-carbon\nbonds and high surface curvature. Electronic polarization of fullerenes is of\nsteady practical importance, since it leads to non-additive interactions and,\ntherefore, to unexpected phenomena. For the first time, hybrid density\nfunctional theory (HDFT) powered Born-Oppenheimer molecular dynamics (BOMD)\nsimulations have been conducted to observe electronic polarization and charge\ntransfer phenomena in the C60 fullerene at finite temperature (350 K). The\nnon-additive phenomena are fostered by the three selected imidazolium-based\nroom-temperature ionic liquids (RTILs). We conclude that although charge\ntransfer appears nearly negligible in these systems, an electronic polarization\nis indeed significant leading to a systematically positive effective\nelectrostatic charge on the C60 fullerene: +0.14e in [EMIM][Cl], +0.21e in\n[EMIM][NO3], +0.17e in [EMIM][PF6]. These results are, to certain extent,\nunexpected providing an inspiration to consider novel C60/RTILs systems. HDFT\nBOMD provides a powerful tool to investigate electronic effects in RTIL and\nfullerene containing nuclear-electronic systems."
    },
    {
        "anchor": "Elinvar effect in $\u03b2-$Ti simulated by on-the-fly trained moment\n  tensor potential: A combination of quantum mechanics calculations with machine learning (ML)\ntechniques can lead to a paradigm shift in our ability to predict materials\nproperties from first principles. Here we show that on-the-fly training of an\ninteratomic potential described through moment tensors provides the same\naccuracy as state-of-the-art {\\it ab inito} molecular dynamics in predicting\nhigh-temperature elastic properties of materials with two orders of magnitude\nless computational effort. Using the technique, we investigate high-temperature\nbcc phase of titanium and predict very weak, Elinvar, temperature dependence of\nits elastic moduli, similar to the behavior of the so-called GUM Ti-based\nalloys [T. Sato {\\ it et al.}, Science {\\bf 300}, 464 (2003)]. Given the fact\nthat GUM alloys have complex chemical compositions and operate at room\ntemperature, Elinvar properties of elemental bcc-Ti observed in the wide\ntemperature interval 1100--1700 K is unique.",
        "positive": "Accurate Distances Measures and Machine Learning of the Texture-Property\n  Relation for Crystallographic Textures Represented by One-Point Statistics: The crystallographic texture of metallic materials is a key microstructural\nfeature that is responsible for the anisotropic behavior, e.g., important in\nforming operations. In materials science, crystallographic texture is commonly\ndescribed by the orientation distribution function, which is defined as the\nprobability density function of the orientations of the monocrystal grains\nconforming a polycrystalline material. For representing the orientation\ndistribution function, there are several approaches such as using generalized\nspherical harmonics, orientation histograms, and pole figure images . Measuring\ndistances between crystallographic textures is essential for any task that\nrequires assessing texture similarities, e.g. to guide forming processes.\nTherefore, we introduce novel distance measures based on (i) the Earth Movers\nDistance that takes into account local distance information encoded in\nhistogram-based texture representations and (ii) a distance measure based on\npole figure images. For this purpose, we evaluate and compare existing distance\nmeasures for selected use-cases. The present study gives insights into\nadvantages and drawbacks of using certain texture representations and distance\nmeasures with emphasis on applications in materials design and optimal process\ncontrol."
    },
    {
        "anchor": "Stabilizing polar phases in binary metal oxides by hole doping: The recent observation of ferroelectricity in the metastable phases of binary\nmetal oxides, such as HfO2, ZrO2, Hf0.5Zr0.5O2, and Ga2O3, has garnered a lot\nof attention. These metastable ferroelectric phases are typically stabilized\nthrough epitaxial growth, alloying, or defect engineering. Here, we propose\nhole doping plays a key role in stabilizing the polar phases in binary metal\noxides. Using first-principles density-functional-theory calculations, we show\nthat holes in these oxides mainly occupy one of the two oxygen sublattices.\nThis hole localization, which is more pronounced in the polar phase than in the\nnonpolar phase, lowers the electrostatic energy of the system, and makes the\npolar phase more stable at sufficiently large concentrations. We demonstrate\nthat this electrostatic mechanism is responsible for stabilization of the\nferroelectric phase of HfO2 aliovalently doped with elements that introduce\nholes to the system, such as La and N. Finally, we show that the spontaneous\npolarization in HfO2 is robust to hole doping, and a large polarization\npersists even under a high concentration of holes.",
        "positive": "Controlling the Infrared Dielectric Function through Atomic-Scale\n  Heterostructures: Surface phonon polaritons (SPhPs) - the surface-bound electromagnetic modes\nof a polar material resulting from the coupling of light with optic phonons -\noffer immense technological opportunities for nanophotonics in the infrared\n(IR) spectral region. Here, we present a novel approach to overcome the major\nlimitation of SPhPs, namely the narrow, material-specific spectral range where\nSPhPs can be supported, called the Reststrahlen band. We use an atomic-scale\nsuperlattice (SL) of two polar semiconductors, GaN and AlN, to create a hybrid\nmaterial featuring layer thickness-tunable optic phonon modes. As the IR\ndielectric function is governed by the optic phonon behavior, such control\nprovides a means to create a new dielectric function distinct from either\nconstituent material and to tune the range over which SPhPs can be supported.\nThis work offers the first glimpse of the guiding principles governing the\ndegree to which the dielectric function can be designed using this approach."
    },
    {
        "anchor": "Reply to Comment by Alexandrov and Bratkovsky [cond-mat/0603467,\n  cond-mat/0606366]: The submitted Comment is based on using an isolated quantum dot approach to\ndiscuss the situation where the coupling to the leads is considerable (not\nnegligible). This finite lead coupling is the situation in most molecular\ntransport junctions. In such situations the population on the molecule is not\nstatic and dynamical effects (fluctuations) are crucial. While the discussion\nin [Phys. Rev. B 67, 235312 (2003)], and in the Comment may well apply for an\nisolated molecule, it is simply irrelevant for the very different transport\nsituation analyzed in our original contribution.",
        "positive": "Hexavalent (Me-W/Mo)-modified (Ba,Ca)TiO$_3$-Bi(Mg,Me)O$_3$ perovskites\n  for high-temperature dielectrics: We report on the synthesis of complex lead-free perovskite-type\n(1-x)(Ba$_{0.8}$Ca$_{0.2}$)TiO$_3$-xBi(Mg$_{0.75}$W$_{0.25}$)O$_3$ (BCT-xBMW)\nand (1-x)(Ba$_{0.8}$Ca$_{0.2}$)TiO$_3$-xBi(Mg$_{0.75}$Mo$_{0.25}$)O$_3$\n(BCT-xBMM) solid solutions via conventional solid-state reaction route. The\nsintering temperature was adjusted as a function of composition x to obtain\ndense samples (relative densities over 95%) at the same time minimizing bismuth\nevaporation. X-ray diffraction analysis shows formation of single-phase\nperovskites for $0 \\le x \\le 0.10$ in the BCT-xBMW series and increasing\nconcentrations of impurity phases for $x \\ge 0.15$ and for $x \\ge 0.05$ in\nBCT-xBMM. A transition from a tetragonal to pseudo-cubic perovskite structure\nis observed in BCT-xBMW and BCT-xBMM at $x = 0.05$. The dielectric response has\nbeen characterized between -60 $^\\circ$C and 300 $^\\circ$C for BCT-xBMW, and\nbetween 30 $^\\circ$C and 300 $^\\circ$C for BCT-xBMM using impedance\nspectroscopy, showing a transition from ferroelectric to relaxor-like behavior\nat $x \\ge 0.05$. Additional polarization and Raman spectroscopy measurements\nreveal the occurrence of highly disordered systems. Analysis of the Raman\nspectra indicates structural phase changes and lattice modifications caused by\nchemical substitution. For the composition\n0.8Ba$_{0.8}$Ca$_{0.2}$TiO$_3$-0.2Bi(Mg$_{0.75}$W$_{0.25}$)O$_3$ a\ntemperature-stable permittivity of about 600 ($\\pm 15$% between 60 $^\\circ$C\nand 300 $^\\circ$C) and small losses of $\\tan\\delta < 0.02$ for $T \\le 230$\n$^\\circ$C at 1 kHz are observed, making it a suitable dielectric material for\nhigh temperature capacitors."
    },
    {
        "anchor": "Hydrogen dynamics and light-induced structural changes in hydrogenated\n  amorphous silicon: We use accurate first principles methods to study the network dynamics of\nhydrogenated amorphous silicon, including the motion of hydrogen. In addition\nto studies of atomic dynamics in the electronic ground state, we also adopt a\nsimple procedure to track the H dynamics in light-excited states. Consistent\nwith recent experiments and computer simulations, we find that dihydride\nstructures are formed for dynamics in the light-excited states, and we give\nexplicit examples of pathways to these states. Our simulations appear to be\nconsistent with aspects of the Staebler-Wronski effect, such as the\nlight-induced creation of well separated dangling bonds.",
        "positive": "Effect of Electron-Phonon and Electron-Impurity Scattering on Electronic\n  Transport Properties of Silicon/Germanium Superlattices: Semiconductor superlattices have been extensively investigated for\nthermoelectric applications, to explore the effects of compositions, interface\nstructures, and lattice strain environments on the reduction of thermal\nconductivity, and improvement of efficiency. Most studies assumed that their\nelectronic properties remain unaffected compared to their bulk counterparts.\nHowever, recent studies demonstrated that electronic properties of silicon\n(Si)/germanium (Ge) superlattices show significant variations depending on\ncompositions and growth substrates. These studies used a constant relaxation\ntime approximation, and ignored the effects of electron scattering processes.\nHere, we consider electron scattering with phonons and ionized impurities, and\nreport first-principles calculations of electronic transport properties\nincluding the scattering rates. We investigate two classes of Si/Ge\nsuperlattices: superlattices with varied compositions grown on identical\nsubstrates and with identical compositions but grown on different substrates.\nWe illustrate the relationship between the energy bands of the superlattices\nand the electron-phonon relaxation times. We model the electron-ionized\nimpurity interaction potentials by accounting for the in-plane and the\ncross-plane structural anisotropy. Our analysis reveals that the inclusion of\nelectron-phonon and electron-impurity scattering processes can lead to\n~1.56-fold improved peak power-factors, compared to that of bulk Si. We observe\nthat superlattices can also display dramatically reduced power-factors for\nspecific lattice strain environments. Such reduction could cancel out\nthermoelectric efficiency improvements due to reduced thermal conductivities.\nOur study provides insight to predict variation of electronic properties due to\nchanges in lattice strain environments, essential for designing superlattices\nwith optimized electronic properties."
    },
    {
        "anchor": "Stabilizing Soil Using Annealed Polyvinyl Alcohol as Long-lasting Binder: Agricultural production heavily exploits the soil, resulting in high erosion\nin cultivated land, which poses a threat to food security and environmental\nsustainability. To address this issue, we stabilize the soil using polyvinyl\nalcohol (PVA). PVA strongly adheres to the soil after mixing and annealing,\nenhancing the cohesive strength of the soil. The PVA-soil withstands the impact\nof water at 7 m/s, protecting it from rainfall-induced erosion. Furthermore,\nthe water-retaining capability and drainage of PVA-soil can be adjusted based\non its sizes. This customized PVA-soil provides optimal growing conditions for\nvarious plants in different climates. Our method contributes to improved soil\nmanagement and conversion.",
        "positive": "Sculpting of lead sulfide nanoparticles by means of acetic acid and\n  dichloroethane: Colloidal lead sulfide is a versatile material with great opportunities to\ntune the bandgap by electronic confinement and to adapt the optical and\nelectrical properties to the target application. We present a new and simple\nsynthetic route to control size and shape of PbS nanoparticles. Increasing\nconcentrations of explicitly added acetic acid are used to tune the shape of\nPbS nanoparticles from quasi-spherical particles via octahedrons to six-armed\nstars. The presence of acetate changes the intrinsic surface energies of the\ndifferent crystal facets and enables the growth along the <100> direction.\nFurthermore, the presence of 1,2-dichloroethane alters the reaction kinetics,\nwhich results in smaller nanoparticles with a narrower size distribution."
    },
    {
        "anchor": "Possible persistence of multiferroic order down to bilayer limit of van\n  der Waals material NiI$_{2}$: Realizing a state of matter in two dimensions has repeatedly proven a novel\nroute of discovering new physical phenomena. Van der Waals (vdW) materials have\nbeen at the center of these now extensive research activities. They offer a\nnatural way of producing a monolayer of matter simply by mechanical\nexfoliation. This work demonstrates that the possible multiferroic state with\ncoexisting antiferromagnetic and ferroelectric orders possibly persists down to\nthe bilayer flake of NiI$_{2}$. By exploiting the optical second-harmonic\ngeneration technique, both magnitude and direction of the ferroelectric order,\narising from the cycloidal spin order, are successfully traced. The possible\nmultiferroic state's transition temperature decreases from 58 K for the bulk to\nabout 20 K for the bilayer. Our observation will spur extensive efforts to\ndemonstrate multi-functionality in vdW materials, which have been tried mostly\nby using heterostructures of singly ferroic ones until now.",
        "positive": "Gas flow-directed growth of aligned carbon nanotubes from nonmetallic\n  seeds: Kite growth is a process that utilizes laminar gas flow in chemical vapor\ndeposition to grow long, well-aligned carbon nanotubes (CNTs) for electronic\napplication. This process uses metal nanoparticles (NPs) as catalytic seeds for\nCNT growth. However, these NPs remain as impurities in the grown CNT. In this\nstudy, nanodiamonds (NDs) with negligible catalytic activity were utilized as\nnonmetallic seeds instead of metal catalysts because they are stable at high\ntemperatures and facilitate the growth of low-defect CNTs without residual\nmetal impurities. Results demonstrate the successful growth of over\n100-$\\mu$m-long CNTs by carefully controlling the growth conditions.\nImportantly, we developed an analysis method that utilizes secondary electron\n(SE) yield to distinguish whether or not CNTs grown from metal impurities. The\nabsence of metallic NPs at the CNT tips was revealed by the SE yield mapping,\nwhereas the presence of some kind of NPs at the same locations was confirmed by\natomic force microscopy (AFM). These results suggest that most of the aligned\nCNTs were grown from nonmetallic seeds, most likely ND-derived NPs, via the\ntip-growth mode. Structural characterizations revealed the high crystallinity\nof CNTs, with relatively small diameters. This study presents the first\nsuccessful use of nonmetallic seeds for kite growth and provides a convincing\nalternative for starting materials to prepare long, aligned CNTs without metal\nimpurities. The findings of this study pave the way for more convenient\nfabrication of aligned CNT-based devices, potentially simplifying the\nproduction process by avoiding the need for the removal of metal impurities."
    },
    {
        "anchor": "Investigation of the Cubic Boron Nitride Nucleation under the High\n  Pressure and the High Temperature: In this paper we have theoretically found the activation energy\n($420.38kJ/mol$) for the transformation from hBN to cBN in the microscopic\nviewpoint. We have introduced an analytical formula representing the dependence\nof nucleus formation time on the activation energy, synthesis pressure and\ntemperature. We have theoretically determined the boundary line of cBN nucleus\nformation region in the $P-T$ phase diagram on the basis of the diffusion\nmechanism of cBN nucleus formation. We have found that the cBN crystal nucleus\nformation time is less than $300ms$ by comparing of the theory and experiment.",
        "positive": "Geometry-diversified Coulomb excitations in trilayer AAB stacking\n  graphene: The lower-symmetry trilayer AAB-stacked graphene exhibits rich electronic\nproperties and thus diverse Coulomb excitations. Three pairs of unusual valence\nand conduction bands create nine available interband excitations for the\nundoped case, in which the imaginary (real) part of the polarizability shows 1D\nsquare root asymmetric peaks and 2D shoulder structures (pairs of antisymmetric\npeaks and logarithm type symmetric peaks). Moreover, the low frequency acoustic\nplasmon, being revealed as a prominent peak in the energy loss spectrum, can\nsurvive in a narrow gap system with the large-density-of-states from the\nvalence band. This type of plasmon mode is similar to that in a narrow gap\ncarbon nanotube. However, the decisive mechanism governing this plasmon is the\nintraband conduction state excitations. Its frequency, intensity and critical\nmomentum exhibit a non-monotonic dependence on the Fermi energy. The\nwell-defined electron-hole excitation boundaries and the higher frequency\noptical plasmons are transformed by varying the Fermi energy. There remain\nsubstantial differences between the electronic properties of trilayer AAB, ABC,\nAAA and ABA graphene stackings."
    },
    {
        "anchor": "Enhancement of rare-earth--transition-metal exchange interaction in\n  Pr$_{2}$Fe$_{17}$ probed by inelastic neutron scattering: The fundamental magnetic interactions of Pr$_{2}$Fe$_{17}$ are studied by\ninelastic neutron scattering and anisotropy field measurements. Data analysis\nconfirms the presence of three magnetically inequivalent sites, and reveals an\nexceptionally large value of the exchange field. The unexpected importance of\n$J$-mixing effects in the description of the ground-state properties of\nPr$_{2}$Fe$_{17}$ is evidenced, and possible applications of related compounds\nare envisaged.",
        "positive": "Antimony thin films demonstrate programmable optical non-linearity: The use of metals of nanometer dimensions to enhance and manipulate\nlight-matter interactions for a range of emerging plasmonics-enabled\nnanophotonic and optoelectronic applications is an interesting, yet not highly\nexplored area of research outside of plasmonics1,2. Even more importantly, the\nconcept of an active metal, i.e. a metal that can undergo an optical\nnon-volatile transition has not been explored. Nanostructure-based applications\nwould have unprecedented impact on both the existing and future of optics with\nthe development of active and nonlinear optical tunabilities in single\nelemental metals3-5. Compared to alloys, pure metals have the material\nsimplicity and uniformity; however single elemental metals have not been viewed\nas tunable optical materials, although they have been explored as viable\nelectrically switchable materials. In this paper we demonstrate for the first\ntime that antimony (Sb), a pure metal, is optically distinguishable between two\nprogrammable states as nanoscale thin films. We then show that these states are\nstable at room temperature, and the states correspond to the crystalline and\namorphous phases of the metal. Crucially from an application standpoint, we\ndemonstrate both its optoelectronic modulation capabilities as well as speed of\nswitching using single sub-picosecond (ps) pulses. The simplicity of depositing\na single metal portends its potential for use in applications ranging from high\nspeed active metamaterials to photonic neuromorphic computing, and opens up the\npossibility for its use in any optoelectronic application where metallic\nconductors with an actively tunable state is important."
    },
    {
        "anchor": "Kinetic theory of nucleation and coarsening: Classical theory of nucleation based on Becker-Doering equations and\ncoarsening for a binary alloy.",
        "positive": "A Taxonomy of Snow Crystal Growth Behaviors: 1. Using c-axis Ice Needles\n  as Seed Crystals: I describe a new approach to the classification of snow crystal morphologies\nthat focuses on the most common growth behaviors that appear in normal air\nunder conditions of constant applied temperature and water-vapor\nsupersaturation. The resulting morphological structures are generally robust\nwith respect to small environmental changes and thus should be especially\namenable to computational modeling. Because spontaneous structure formation\ndepends on initial conditions, the choice of seed crystal can be an important\nconsideration, and I have found that slender c-axis ice needles provide an\nexceptionally good starting point for this series of investigations. A sharp\nneedle tip exposes a single basal surface that often simplifies subsequent\nmorphological development, and the absence of a nearby substrate allows for the\nexploration of a broad range of supersaturations with well-controlled boundary\nconditions. The overarching goal of this endeavor is to facilitate detailed\nquantitative comparisons between laboratory ice-growth experiments and\ncorresponding computational models, which will should greatly improve our\nunderstanding of the ice/vapor molecular attachment kinetics as well as our\nability to model diffusion-limited growth dynamics in the ice/vapor system.\nThis specific case-study of water ice connects broadly to many areas in aqueous\nchemistry, cryobiology, and environmental science, while the physical\nprinciples of molecular attachment kinetics and diffusion-limited growth apply\nmore generally to other systems in crystal growth and materials science."
    },
    {
        "anchor": "Giant nonlocal edge conduction in the axion insulator state of MnBi2Te4: The recently discovered antiferromagnetic (AFM) topological insulator (TI)\nMnBi2Te4 represents a versatile material platform for exploring exotic\ntopological quantum phenomena in nanoscale devices. It has been proposed that\neven-septuple-layer (even-SL) MnBi2Te4 can host helical hinge currents with\nunique nonlocal behavior, but experimental confirmation is still lacking. In\nthis work, we report transport studies of exfoliated MnBi2Te4 flakes with\nvaried thicknesses down to the few-nanometer regime. We observe giant nonlocal\ntransport signals in even-SL devices when the system is in the axion insulator\nstate but vanishingly small nonlocal signal in the odd-SL devices at the same\nmagnetic field range. In conjunction with theoretical calculations, we\ndemonstrate that the nonlocal transport is via the helical edge currents mainly\ndistributed at the hinges between the side and top/bottom surfaces. The helical\nedge currents in the axion insulator state may find unique applications in\ntopological quantum devices.",
        "positive": "Multiscale Modeling of Peritectic Reaction Growth: Peritectic growth of bulk superconducting cuprate perovskite, like\nYBa2Cu3O7-x has been studied. The microstructure features are recalled. The\nsimplest model giving the best description of the microstructure complexity at\nthe mesoscopic scale is an Eden model adapted to chemical reactions. A\nrepulsive dynamical interaction between the front and the solid 211 particles,\nrejected by the solidifying matrix, is also taken into account. A growth\nprobability-with chemical reaction and pushing-transfer matrix method is\ndeveloped. The simulations put into evidence the effect of the initial 211 size\ndistribution on the microstructure."
    },
    {
        "anchor": "Enhanced Thermoelectric Performance and Anomalous Seebeck Effects in\n  Topological Insulators: Improving the thermoelectric figure of merit zT is one of the greatest\nchallenges in material science. Recent discovery of topological insulators\n(TIs) offers new promise in this prospect. In this work, we demonstrate\ntheoretically that zT is strongly size dependent in TI, and the size parameter\ncan be tuned to enhance zT to be significantly greater than 1. Furthermore, we\nshow that the life time of the edge states in TI is strongly energy dependent,\nleading to large and anomalous Seebeck effects with an opposite sign to the\nHall effect. These striking properties make TIs the promising material for\nthermoelectrics science and technology.",
        "positive": "The Initiation of Shear Band Formation in Deformed Metallic Glasses from\n  Soft Localized Domains: It has long been thought that shear band (SB) formation in amorphous solids\ninitiates from relatively 'soft' regions in the material in which large-scale\nnon-affine deformations become localized. The test of this hypothesis requires\nan effective means of identifying 'soft' regions and their evolution as the\nmaterial is deformed to varying degrees, where the metric of 'softness' must\nalso account for the effect of temperature on local material stiffness. We show\nthat the mean square atomic displacement on a caging timescale <u2>, the\n'Debye-Waller factor', provides a useful method for estimating the shear\nmodulus of the entire material and, by extension, the material stiffness at an\natomic scale. Based on this 'softness' metrology, we observe that SB formation\nindeed occurs through the strain-induced formation of localized soft regions in\nour deformed metallic glass free-standing films. Unexpectedly, the critical\nstrain condition of SB formation occurs when the softness (<u2>) distribution\nwithin the emerging soft regions approaches that of the interfacial region in\nits undeformed state, initiating an instability with similarities to the\ntransition to turbulence. Correspondingly, no SBs arise when the material is so\nthin that the entire material can be approximately described as being\n'interfacial' in nature. We also quantify relaxation in the glass and the\nnature and origin of highly non-Gaussian particle displacements in the\ndynamically heterogeneous SB regions at times longer than the caging time."
    },
    {
        "anchor": "Photovoltage Bleaching in Bulk Heterojunction Solar Cells through\n  Occupation of the Charge Transfer State: We observe a strong peak in the capacitive photocurrent of a MDMO-PPV / PCBM\nbulk heterojunction solar cell for excitation below the absorbance threshold\nenergy. Illumination at the peak energy blocks charge capture at other\nwavelengths, and causes the photovoltage to drop dramatically. These results\nsuggest that the new peak is due to a charge transfer state, which provides a\npathway for charge separation and photocurrent generation in the solar cell.",
        "positive": "Magnetic torque oscillations from warped helical surface states in\n  topological insulators: A magnetic torque method is proposed that probes the warping and mass gap of\nDirac cone surface states in topological insulators like Bi2X3 (X=Se,Te). A\nrotating field parallel to the surface induces a paramagnetic moment in the\nhelical surface states for nonzero warping. It is non-collinear with the\napplied field and therefore produces torque oscillations as function of the\nfield angle which are a direct signature of the surface states. The torque\ndependence on field strength and angle, the chemical potential and the Dirac\ncone parameters like warping strength and mass gap is calculated. It is shown\nthat the latter leads to a symmetry reduction in the fourfold torque\noscillations."
    },
    {
        "anchor": "Tuning epitaxial graphene sensitivity to water by hydrogen intercalation: The effects of humidity on the electronic properties of quasi-free standing\none layer graphene (QFS 1LG) are investigated via simultaneous\nmagneto-transport in the van der Pauw geometry and local work function\nmeasurements in a controlled environment. QFS 1LG on 4H-SiC(0001) is obtained\nby hydrogen intercalation of the interfacial layer. In this system, the carrier\nconcentration experiences a two-fold increase in sensitivity to changes in\nrelative humidity as compared to the as-grown epitaxial graphene. This enhanced\nsensitivity to water is attributed to the lowering of the hydrophobicity of QFS\n1LG, which results from spontaneous polarization of 4H-SiC(0001) strongly\ninfluencing the graphene. Moreover, the superior carrier mobility of the QFS\n1LG system is retained even at the highest humidity. The work function maps\nconstructed from Kelvin probe force microscopy also revealed higher sensitivity\nto water for 1LG compared to 2LG in both QFS 1LG and as-grown systems. These\nresults point to a new field of applications for QFS 1LG, i.e., as humidity\nsensors, and the corresponding need for metrology in calibration of\ngraphene-based sensors and devices.",
        "positive": "Unveiling the interaction mechanisms of electron and X-ray radiation\n  with halide perovskite semiconductors using scanning nano-probe diffraction: The interaction of high-energy electrons and X-ray photons with soft\nsemiconductors such as halide perovskites is essential for the characterisation\nand understanding of these optoelectronic materials. Using nano-probe\ndiffraction techniques, which can investigate physical properties on the\nnanoscale, we perform studies of the interaction of electron and X-ray\nradiation with state-of-the-art\n(FA$_{0.79}$MA$_{0.16}$Cs$_{0.05}$)Pb(I$_{0.83}$Br$_{0.17}$)$_3$ hybrid halide\nperovskite films (FA, formamidinium; MA, methylammonium). We track the changes\nin the local crystal structure as a function of fluence using scanning electron\ndiffraction and synchrotron nano X-ray diffraction techniques. We identify\nperovskite grains from which additional reflections, corresponding to PbBr$_2$,\nappear as a crystalline degradation phase after fluences of ~200\ne$^-${\\AA}$^{-2}$. These changes are concomitant with the formation of small\nPbI$_2$ crystallites at the adjacent high-angle grain boundaries, with the\nformation of pinholes, and with a phase transition from tetragonal to cubic. A\nsimilar degradation pathway is caused by photon irradiation in nano-X-ray\ndiffraction, suggesting common underlying mechanisms. Our approach explores the\nradiation limits of these materials and provides a description of the\ndegradation pathways on the nanoscale. Addressing high-angle grain boundaries\nwill be critical for the further improvement of halide polycrystalline film\nstability, especially for applications vulnerable to high-energy radiation such\nas space photovoltaics."
    },
    {
        "anchor": "Temperature dependence of anisotropic thermal conductivity tensor of\n  bulk black phosphorus: To date, the intrinsic thermal conductivity tensor of bulk black phosphorus\n(BP), an important 2D material, is still unknown, since recent studies focus on\nBP flakes not on bulk BP. Here we report the anisotropic thermal conductivity\ntensor of bulk BP, for temperature range 80 - 300 K. Our measurements are\nsimilar to prior measurements on submicron BP flakes along zigzag and armchair\naxes, but are >25% higher in the through-plane axis, suggesting that phonon\nmean-free-paths are substantially longer in the through-plane direction. We\nfind that despite the anisotropy in thermal conductivity, phonons are\npredominantly scattered by the same Umklapp processes in all directions. We\nalso find that the phonon relaxation time is rather isotropic in the basal\nplanes, but is highly anisotropic in the through-plane direction. Our work\nadvances fundamental knowledge of anisotropic scattering of phonons in BP and\nis an important benchmark for future studies on thermal properties of BP\nnanostructures.",
        "positive": "Symmetry-Adapted Machine-Learning for Tensorial Properties of Atomistic\n  Systems: Statistical learning methods show great promise in providing an accurate\nprediction of materials and molecular properties, while minimizing the need for\ncomputationally demanding electronic structure calculations. The accuracy and\ntransferability of these models are increased significantly by encoding into\nthe learning procedure the fundamental symmetries of rotational and\npermutational invariance of scalar properties. However, the prediction of\ntensorial properties requires that the model respects the appropriate geometric\ntransformations, rather than invariance, when the reference frame is rotated.\nWe introduce a formalism that can be used to perform machine-learning of\ntensorial properties of arbitrary rank for general molecular geometries. To\ndemonstrate it, we derive a tensor kernel adapted to rotational symmetry, which\nis the natural generalization of the smooth overlap of atomic positions (SOAP)\nkernel commonly used for the prediction of scalar properties at the atomic\nscale. The performance and generality of the approach is demonstrated by\nlearning the instantaneous electrical response of water oligomers of increasing\ncomplexity, from the isolated molecule to the condensed phase."
    },
    {
        "anchor": "An In Situ Study of the Role of Pressure on Fe Recrystallization and\n  Grain Growth during Thermomechanical Processing: Elevated pressures are encountered in many metal forming processes that can\nalter microstructural evolution rates. Here we measure rate changes with\npressure in recrystallization and grain growth in Fe through adaptation of\nsynchrotron-compatible multi-anvil presses, originally designed for study of\nthe mantle. Recrystallization and grain growth are monitored in situ using\nhigh-energy X-ray diffraction. Principal component analysis applied to the\ndiffraction images is used to quantify evolution rates, with increasing\npressure significantly slowing the process.",
        "positive": "VNCB defect as source of single photon emission from hexagonal boron\n  nitride: Single photon emitters in 2D hexagonal boron nitride (hBN) have attracted a\nconsiderable attention because of their highly intense, stable, and\nstrain-tunable emission. However, the precise source of this emission, in\nparticular the detailed atomistic structure of the involved crystal defect,\nremains unknown. In this work, we present first-principles calculations of the\nvibrationally resolved optical fingerprint of the spin-triplet (2)(_^3)B_1 to\n(1)(_^3)B_1 transition of the VNCB point defect in hBN. Based on the excellent\nagreement with experiments for key spectroscopic quantities such as the\nemission frequency and polarization, the photoluminescence (PL) line shape,\nHuang-Rhys factor, Debye-Waller factor, and re-organization energy, we\nconclusively assign the observed single photon emission at ~2eV to the VNCB\ndefect. Our work thereby resolves a long-standing debate about the exact\nchemical nature of the source of single photon emission from hBN and\nestablishes the microscopic understanding necessary for controlling and\napplying such photons for quantum technological applications."
    },
    {
        "anchor": "Electronic properties of AlN crystal doped with Cr, Mn and Fe: The spin-resolved electronic energy band spectra, as well as partial and\ntotal density of electronic states of the crystal AlN, doped with Cr, Mn and\nFe, have been evaluated within the projector augmented waves (PAW) approach by\nmeans of the ABINIT code. The Hartree-Fock exchange for correlated electrons is\nused to describe the correlated orbitals in the PAW framework. The calculated\none-electron energies for electrons of spin up and down are very different. We\nhave found that all the considered crystals are ferromagnetic.",
        "positive": "Role of temperature-dependent electron trapping dynamics in the\n  optically driven nanodomain transformation in a PbTiO${_3}$/SrTiO${_3}$\n  superlattice: The spontaneously formed striped polarization nanodomain configuration of a\nPbTiO${_3}$/SrTiO${_3}$ superlattice transforms to a uniform polarization state\nunder above-bandgap illumination with a time dependence varying with the\nintensity of optical illumination and a well-defined threshold intensity.\nRecovery after the end of illumination occurs over a temperature-dependent\nperiod of tens of seconds at room temperature and shorter times at elevated\ntemperatures. A model in which the screening of the depolarization field\ndepends on the population of trapped electrons correctly predicts the observed\ntemperature and optical intensity dependence."
    },
    {
        "anchor": "Anharmonic thermodynamic properties and phase boundary across the\n  post-perovskite transition in MgSiO$_3$: To address the effects of lattice anharmonicity across the perovskite to\npost-perovskite transition in MgSiO$_3$, we conduct calculations using the\nphonon quasiparticle (PHQ) approach. The PHQ is based on \\textit{ab initio}\nmolecular dynamics and, in principle, captures full anharmonicity. Free\nenergies in the thermodynamic limit ($N \\rightarrow \\infty$) are computed using\ntemperature-dependent quasiparticle dispersions within the phonon gas model.\nSystematic results on anharmonic thermodynamic properties and phase boundary\nare reported. Both the local density approximation (LDA) and the generalized\ngradient approximation (GGA) calculations are performed to provide confident\nconstraints on these properties. Anharmonic effects are demonstrated by\ncomparing results with those obtained using the quasiharmonic approximation\n(QHA). The inadequacy of the QHA is indicated by its overestimation of thermal\nexpansivity and thermodynamic Gr\\\"{u}neisen parameter and its converged\nisochoric heat capacity in the high-temperature limit. The PHQ phase boundary\nhas a Clapeyron slope ($dP/dT$) that increases with temperature. This result\ncontrasts with the nearly zero curvature of the QHA phase boundary.\nAnharmonicity bends the phase boundary to lower temperatures at high pressures.\nImplications for the double-crossing of the phase boundary by the mantle\ngeotherm are discussed.",
        "positive": "Electric-field switchable magnetization via the Dzyaloshinskii-Moriya\n  interaction: FeTiO_3 versus BiFeO_3: In this article we review and discuss a mechanism for coupling between\nelectric polarization and magnetization that can ultimately lead to\nelectric-field switchable magnetization. The basic idea is that a ferroelectric\ndistortion in an antiferromagnetic material can \"switch on\" the\nDzyaloshinskii-Moriya interaction which leads to a canting of the\nantiferromagnetic sublattice magnetizations, and thus to a net magnetization.\nThis magnetization M is coupled to the polarization P via a trilinear free\nenergy contribution of the form P(M x L), where L is the antiferromagnetic\norder parameter. In particular, we discuss why such an invariant is present in\nR3c FeTiO_3 but not in the isostructural multiferroic BiFeO_3. Finally, we\nconstruct symmetry groups that in general allow for this kind of\nferroelectrically-induced weak ferromagnetism."
    },
    {
        "anchor": "Maximum thermal conductivity of aligned single wall carbon nanotubes: I estimate maximum thermal conductivity $\\kappa$ of a perfectly aligned\nbundle of single wall carbon nanotubes. Each row of aligned nanotubes has a\ndiscrete structure. It consists of segments of nanotubes with length $L$. The\nspacing between the segments block the phonon path through the row. Only the\nscattering due to the finite length of the segments is taken into account. The\nresult is that the 'effective'' mean free path is of the order of $L/7$. For 1\nmicron tubes (10,10) we get maximum value of $\\kappa\\approx 300$W/m K at room\ntemperature. This result is in a reasonable agreement with the experiment by\nHone {\\it et al.} assuming that in their samples $L\\approx 1\\mu{\\rm m}$",
        "positive": "Tuning perpendicular magnetic anisotropy in (Ga,Mn)(As,P) by thermal\n  annealing: We have investigated the effects of post growth low temperature annealing on\nthe magnetic, electrical and structural properties of\n(Ga_0.94,Mn_0.06)(As_0.9,P_0.1) layers grown by molecular beam epitaxy. By\ncontrolling the annealing time we are able to tune the magnetic anisotropy\nbetween an easy axis in the plane for the as-grown samples, to an easy axis\nperpendicular to the plane for fully annealed samples. The increase of the\ncarrier density, as a result of annealing, is found to be the primary reason\nfor the change in magnetic anisotropy, in qualitative agreement with\ntheoretical predictions."
    },
    {
        "anchor": "Emergent Spin-Filter at the interface between Ferromagnetic and\n  Insulating Layered Oxides: We report a strong effect of interface-induced magnetization on the transport\nproperties of magnetic tunnel junctions consisting of ferromagnetic manganite\nLa$_{0.7}$Ca$_{0.3}$MnO$_{3}$ and insulating cuprate PrBa$_{2}$Cu$_{3}$O$_{7}$.\nContrary to the typically observed steady increase of the tunnel\nmagnetoresistance with decreasing temperature, this system exhibits a sudden\nanomalous decrease at low temperatures. Interestingly, this anomalous behavior\ncan be attributed to the competition between the positive spin polarization of\nthe manganite contacts and the negative spin-filter effect from the\ninterface-induced Cu magnetization.",
        "positive": "Generation linewidth of an auto-oscillator with a nonlinear frequency\n  shift: Spin-torque nano-oscillator: It is shown that the generation linewidth of an auto-oscillator with a\nnonlinear frequency shift (i.e. an auto-oscillator in which frequency depends\non the oscillation amplitude) is substantially larger than the linewidth of a\nconventional quasi-linear auto-oscillator due to the renormalization of the\nphase noise caused by the nonlinearity of the oscillation frequency. The\ndeveloped theory, when applied to a spin-torque nano-contact auto-oscillator,\npredicts a minimum of the generation linewidth when the nano-contact is\nmagnetized at a critical angle to its plane, corresponding to the minimum\nnonlinear frequency shift, in good agreement with recent experiments."
    },
    {
        "anchor": "Parametrization of Stillinger-Weber Potential Based on Valence Force\n  Field Model: Application to Single-Layer MoS2 and Black Phosphorus: We propose to parametrize the Stillinger-Weber potential for covalent\nmaterials starting from the valence force field model. All geometrical\nparameters in the Stillinger-Weber potential are determined analytically\naccording to the equilibrium condition for each individual potential term,\nwhile the energy parameters are derived from the valence force field model.\nThis parametrization approach transfers the accuracy of the valence force field\nmodel to the Stillinger-Weber potential. Furthermore, the resulting\nStilliinger-Weber potential supports for stable molecular dynamics simulations,\nas each potential term is at energy minimum state separately at the equilibrium\nconfiguration. We employ this procedure to parametrize Stillinger-Weber\npotentials for the single-layer MoS2 and black phosphorous. The obtained\nStillinger-Weber potentials predict accurate phonon spectrum and mechanical\nbehaviors. We also provide input scripts of these Stillinger-Weber potentials\nused by publicly available simulation packages including GULP and LAMMPS.",
        "positive": "Intrinsic quantum anomalous Hall phase induced by proximity in\n  germanene/Cr$_2$Ge$_2$Te$_6$ van der Waals heterostructure: A van der Waals heterostructure combined with intrinsic magnetism and\ntopological orders have recently paved attractive avenues to realize quantum\nanomalous Hall effects. In this work, using first-principles calculations and\neffective model analysis, we propose that the robust quantum anomalous Hall\nstates with sizable band gaps emerge in the van der Waals heterostructure of\ngermanene/Cr$_2$Ge$_2$Te$_6$. This heterostructure possesses high thermodynamic\nstability, thus facilitating its experimental fabrication. Furthermore, we\nuncover that the proximity effect enhances the coupling between the germanene\nand Cr$_2$Ge$_2$Te$_6$ layers, inducing the nontrivial band gaps in a wide\nrange from 29 meV to 72 meV. The chiral edge states inside the band gap,\nleading to Hall conductance quantized to $-e^2/h$, are clearly visible. This\nfindings provide an ideal candidate to detect the quantum anomalous Hall states\nand realize further applications to nontrivial quantum transport at a high\ntemperature."
    },
    {
        "anchor": "Ab initio Green-Kubo Approach for the Thermal Conductivity of Solids: We herein present a first-principles formulation of the Green-Kubo method\nthat allows the accurate assessment of the non-radiative thermal conductivity\nof solid semiconductors and insulators in equilibrium ab initio molecular\ndynamics calculations. Using the virial for the nuclei, we propose a unique ab\ninitio definition of the heat flux. Accurate size- and time convergence are\nachieved within moderate computational effort by a robust, asymptotically exact\nextrapolation scheme. We demonstrate the capabilities of the technique by\ninvestigating the thermal conductivity of extreme high and low heat conducting\nmaterials, namely diamond Si and tetragonal ZrO$_2$.",
        "positive": "Room-temperature near-infrared silicon carbide nanocrystalline emitters\n  based on optically aligned spin defects: Bulk silicon carbide (SiC) is a very promising material system for\nbio-applications and quantum sensing. However, its optical activity lies beyond\nthe near infrared spectral window for in-vivo imaging and fiber communications\ndue to a large forbidden energy gap. Here, we report the fabrication of SiC\nnanocrystals and isolation of different nanocrystal fractions ranged from 600\nnm down to 60 nm in size. The structural analysis reveals further fragmentation\nof the smallest nanocrystals into ca. 10-nm-size clusters of high crystalline\nquality, separated by amorphization areas. We use neutron irradiation to create\nsilicon vacancies, demonstrating near infrared photoluminescence. Finally, we\ndetect, for the first time, room-temperature spin resonances of these silicon\nvacancies hosted in SiC nanocrystals. This opens intriguing perspectives to use\nthem not only as in-vivo luminescent markers, but also as magnetic field and\ntemperature sensors, allowing for monitoring various physical, chemical and\nbiological processes."
    },
    {
        "anchor": "Optical properties and charge-transfer excitations in\n  edge-functionalized all-graphene nanojunctions: We investigate the optical properties of edge-functionalized graphene\nnanosystems, focusing on the formation of junctions and charge transfer\nexcitons. We consider a class of graphene structures which combine the main\nelectronic features of graphene with the wide tunability of large polycyclic\naromatic hydrocarbons. By investigating prototypical ribbon-like systems, we\nshow that, upon convenient choice of functional groups, low energy excitations\nwith remarkable charge transfer character and large oscillator strength are\nobtained. These properties can be further modulated through an appropriate\nwidth variation, thus spanning a wide range in the low-energy region of the\nUV-Vis spectra. Our results are relevant in view of designing all-graphene\noptoelectronic nanodevices, which take advantage of the versatility of\nmolecular functionalization, together with the stability and the electronic\nproperties of graphene nanostructures.",
        "positive": "Trends in atomistic simulation software usage: Driven by the unprecedented computational power available to scientific\nresearch, the use of computers in solid-state physics, chemistry and materials\nscience has been on a continuous rise. This review focuses on the software used\nfor the simulation of matter at the atomic scale. We provide a comprehensive\noverview of major codes in the field, and analyze how citations to these codes\nin the academic literature have evolved since 2010. An interactive version of\nthe underlying data set is available at https://atomistic.software ."
    },
    {
        "anchor": "Element-Resolved Corrosion Analysis of Stainless-Type Glass-Forming\n  Steels: Ultrathin passive films effectively prevent the chemical attack of stainless\nsteel grades in corrosive environments; their stability critically depends on\nthe interplay between structure and chemistry of the constituents Fe-Cr-Mo. In\nparticular, nanoscale inhomogeneities along the surface can have a tremendous\nimpact on material failure, but are yet barely understood. Addressing a\nstainless-type glass-forming Fe50Cr15Mo14C15B6 alloy and utilizing a\ncombination of complementary high-resolution analytical techniques, we relate\nnear-atomistic insight into different gradual nanostructures with time- and\nelement-resolved dissolution behavior. The progressive elemental segregation on\nthe nanoscale is followed in its influence on the concomitant degree of\npassivity. A detrimental transition from Cr-controlled passivity to\nMo-controlled breakdown is dissected atom-by-atom demonstrating the importance\nof nanoscale knowledge for understanding corrosion.",
        "positive": "Nanostrucure of Hybrid Plasmonic-Potonic Crystal Formed on\n  Gel-Immobilized Colloidal Crystal Observer by AFM after Drying: Aiming at fabrication of hybrid plasmonic-photonic crystals, gel-immobilized\ncolloidal crystals made of a polystyrene colloidal suspension and an N-(Hydroxy\nmethyl)acrylamid-based gel were immersed into an aqueous dispersion of gold\nnanoparticles. Atomic force microscope (AFM) observations have been performed\nfor the gel-immobilized colloidal crystals with gold nanoparticles deposited on\ntheir surfaces. In the present study, the diameter of a colloidal sphere was\nc.a. 190 nm. The diameter of a gold nanoparticle was the same as in a\npreliminary study, c.a. 40 nm. Various immersion times up to two hours were\ntested. Surface of a sample of 2 hr immersion has been observed. Prior to the\nAFM observation, the sample was dried in a desiccator for 18 hrs. We have\nidentified a face-centered cubic {111} structure of a colloidal crystal of\nnearly close packing. Nanoparticles isolated with one another have been\nobserved on the surface of gel-immobilized crystal, which can be regarded as\ngold nanoparticles from their sizes."
    },
    {
        "anchor": "Semiconductor Electron-Phonon Equations: a Rung Above Boltzmann in the\n  Many-Body Ladder: Starting from the {\\em ab initio} many-body theory of electrons and phonons,\nwe go through a series of well defined simplifications to derive a set of\ncoupled equations of motion for the electronic occupations and polarizations,\nnuclear displacements as well as phononic occupations and coherences. These are\nthe semiconductor electron-phonon equations (SEPE), sharing the same scaling\nwith system size and propagation time as the Boltzmann equations. At the core\nof the SEPE is the {\\em mirrored} Generalized Kadanoff-Baym ansatz (GKBA) for\nthe Green's functions, an alternative to the standard GKBA which we show to\nlead to unstable equilibrium states. The SEPE treat coherent and incoherent\ndegrees of freedom on equal footing, widen the scope of the semiconductor Bloch\nequations and Boltzmann equations, and reduce to them under additional\nsimplifications. The new features of the SEPE pave the way for first-principles\nstudies of phonon squeezed states and coherence effects in time-resolved\nabsorption and diffraction experiments.",
        "positive": "Spin-polarized two-dimensional electron/hole gas at the interface of\n  non-magnetic semiconducting half-Heusler compounds: Modified Slater-Pauling\n  rule for half-metallicity at the interface: Half-Heusler compounds with 18 valence electrons per unit cell are well-known\nnon-magnetic semiconductors. Employing first-principles electronic band\nstructure calculations, we study the interface properties of the half-Heusler\nheterojunctions based on FeVSb, CoTiSb, CoVSn, and NiTiSn compounds, which\nbelong to this category of materials. Our results show that several of these\nheterojunction interfaces become not only metallic but also magnetic. The\nemergence of spin-polarization is accompanied by the formation of\ntwo-dimensional electron gas (2DEG) or hole gas (2DHG) at the interface. We\nqualitatively discuss the origin of the spin polarization at the interfaces on\nthe basis of the Stoner model. For the cases of magnetic interfaces where\nhalf-metallicity is also present, we propose a modified Slater-Pauling rule\nsimilar to the one for bulk half-metallic half-Heusler compounds. Additionally,\nwe calculate exchange parameters, Curie temperatures and magnetic anisotropy\nenergies for magnetic interfaces. Our study, combined with the recent\nexperimental evidence for the presence of 2DEG at CoTiSb/NiTiSn heterojunctions\nmight motivate future efforts and studies toward the experimental realization\nof devices using the proposed heterojunctions."
    },
    {
        "anchor": "Photoinduced polarons in polymers. Time-resolved ESR analysis of polaron\n  pairs in polymer:fullerene blends: The work concerns the analysis of experimental time-resolved ESR spectra in\nphotoexcited polymer:fullerene blend, consisting of poly(3-hexilthiophene) and\nfullerene [6,6]-phenyl C_{61} -butyric acid methyl ester (at low temperature T\n= 100 K). The spectra are assumed to be determined by spin-coherent pairs of\ncharged polarons P^{+} and P^{-} generated in the singlet state. The analysis\nis made within simple model of a set of first order processes, in which\nP^{+}P$^{-}-pair spin evolution is described by the stochastic Liouville\nequation, allowing for fairly accurate description of experimental results.\nSimple analytical interpretation of obtained numerical results demonstrates\nthat trESR spectra can be represented as a superposition of antiphase and CIDEP\ncontributions together with the conventional thermal one. These contributions\nare shown to change their signs with the increase of time in agreement with\nexperimental observations.",
        "positive": "Metastable ferroelectricity in optically strained $SrTiO_3$: Fluctuating orders in solids are generally considered high-temperature\nprecursors of broken symmetry phases. However, in some cases these fluctuations\npersist to zero temperature and prevent the emergence of long-range order, as\nfor example observed in quantum spin and dipolar liquids. $SrTiO_3$ is a\nquantum paraelectric in which dipolar fluctuations grow when the material is\ncooled, although a long-range ferroelectric order never sets in. We show that\nthe nonlinear excitation of lattice vibrations with mid-infrared optical pulses\ncan induce polar order in $SrTiO_3$ up to temperatures in excess of 290 K. This\nmetastable phase, which persists for hours after the optical pump is\ninterrupted, is evidenced by the appearance of a large second-order optical\nnonlinearity that is absent in equilibrium. Hardening of a low-frequency mode\nindicates that the polar order may be associated with a photo-induced\nferroelectric phase transition. The spatial distribution of the optically\ninduced polar domains suggests that a new type of photo-flexoelectric coupling\ntriggers this effect."
    },
    {
        "anchor": "Sr- and Ni-doping in ZnO nanorods synthesized by simple wet chemical\n  method as excellent materials for CO and CO2 gas sensing: In this study, the effect of Sr- and Ni-doping on microstructural,\nmorphological and sensing properties of ZnO nanorods has been investigated.\nNanorods with different Sr and Ni loadings were prepared using a simple wet\nchemical method and characterized by means of scanning electron microscopy\n(SEM), X-ray diffraction (XRD) and photoluminescence (PL) analysis. XRD data\nconfirmed that Sr- and Ni-doped samples maintainsthe wurtzite hexagonal\nstructure of pure ZnO. However, unlikes Sr, Ni doping modifies the nanorod\nmorphology, increases the surface area (SA) and decreases the ratio of\nIUV/Igreen photoluminescence peak to a greater extent. Sensing tests were\nperformed on thick films resistive planar devices for monitoring CO and CO2, as\nindicators of indoor air quality.The effect of the operating temperature,\nnature and loading of dopant on the sensibility and selectivity of the\nfabricated sensors towards these two harmful gases were investigated. The gas\nsensing characteristics of Ni- and Sr-doped ZnO based sensors showed a\nremarkable enhancement (i. e. the response increased and shifted towards lower\ntemperature for both gases) compared to ZnO-based one, demonstrating that these\nZnO nanostructures are promising to fabricate sensor devices for monitoring\nindoor air quality.",
        "positive": "In the search of new electrocaloric materials: Fast ion conductors: We analyse the effects of applying an electric field on the critical\ntemperature, Ts, at which superionicity appears in archetypal fast ion\nconductor CaF2 by means of molecular dynamics simulations. We find that the\nonset of superionicity can be reduced by about 100K when relatively small\nelectric fields of ~50KV/cm are employed. Under large enough electric fields,\nhowever, ionic conductivity is depleted. The normal to superionic phase\ntransition is characterised by a large increase of entropy, thereby sizeable\nelectrocaloric effects can be realised in fast ion conductors that are\npromising for solid-state cooling applications."
    },
    {
        "anchor": "Thermal transport in nanocrystalline graphene investigated by\n  approach-to-equilibrium molecular dynamics simulations: Approach-to-equilibrium molecular dynamics simulations have been used to\nstudy thermal transport in nanocrystalline graphene sheets. Nanostructured\ngraphene has been created using an iterative process for grain growth from\ninitial seeds with random crystallographic orientations. The resulting cells\nhave been characterized by the grain size distribution based on the radius of\ngyration, by the number of atoms in each grain and by the number of atoms in\nthe grain boundary. Introduction of nanograins with a radius of gyration of 1\nnm has led to a significant reduction in the thermal conductivity to 3% of the\nvalue in single crystalline graphene. Analysis of the vibrational density of\nstates has revealed a general reduction of the vibrational intensities and\nbroadening of the peaks when nanograins are introduced which can be attributed\nto phonon scattering in the boundary layer. The thermal conductivity has been\nevaluated as a function of the grain size with increasing size up to 14 nm and\nit has been shown to follow an inverse rational function. The grain size\ndependent thermal conductivity could be approximated well by a function where\ntransport is described by a connection in series of conducting elements and\nresistances (at boundaries).",
        "positive": "Carbon p Electron Ferromagnetism in Silicon Carbide: Ferromagnetism can occur in wide-band gap semiconductors as well as in\ncarbon-based materials when specific defects are introduced. It is thus\ndesirable to establish a direct relation between the defects and the resulting\nferromagnetism. Here, we contribute to revealing the origin of defect-induced\nferromagnetism using SiC as a prototypical example. We show that the long-range\nferromagnetic coupling can be attributed to the p electrons of the\nnearest-neighbor carbon atoms around the VSiVC divacancies. Thus, the\nferromagnetism is traced down to its microscopic, electronic origin."
    },
    {
        "anchor": "Higher-Order Harmonic Generation caused by Elliptically Polarized\n  Electric Fields in Solid-State Materials: We theoretically investigated the dependence of higher-order harmonic\ngeneration (HHG) in solid-state materials on the ellipticity of the electric\nfield. We found that in the multiphoton absorption and ac Zener regimes, the\nintensity of HHG monotonically decreases with increasing ellipticity of the\nincident electric field, while in the semimetal regime, the intensity reaches a\nmaximum for finite values of ellipticity. Moreover, the characteristics of the\npolarization of the emitted HHG change depending on the field intensity; only\nparallel emissions with respect to the major axis exist in the multiphoton\nabsorption and ac Zener regimes, while both parallel and perpendicular\nemissions exist in the semimetal regime. These peculiar characteristics of the\nsemimetal regime can be understood on the basis of changes in the HHG mechanism\nand may be able to be identified in experiments utilizing solid-state materials\nsuch as narrow-gap semiconductors.",
        "positive": "Magnetically and electrically controllable valley splittings in MXene\n  monolayers: The modulation of the valley structure in two-dimensional valley materials is\nvital in the field of valleytronics. The multiferroicity provides possibility\nfor multiple modulations of the valley, including the magnetic and electric\nmeans. Based on the first-principle calculations, we study the valley\nproperties and associated manipulations of multiferroic Co$_2$CF$_2$ monolayers\nwith different stacking patterns. Our calculations show that the Co$_2$CF$_2$\nmonolayer in the H$^{\\prime}$ phase is a ferrovalley material, with sizable\nvalley splittings. By rotating the magnetization direction, the valley\nsplittings can be tuned for both the magnitude and sign. The electric field,\ndriving the reversal of the electric polarization, can also change the\nmagnitude of the valley splittings. Besides, a metastable T$^{\\prime}$ phase\nexhibits valley splittings as well, of which the magnitude and sign can be\nsimultaneously controlled by applied magnetic and electric fields. These\nfindings offer a practical way for realizing highly tunable valleys by\nmultiferroic couplings."
    },
    {
        "anchor": "Quasiparticle Interference Evidence of the Topological Fermi Arc States\n  in Chiral Fermionic Semimetal CoSi: Chiral fermions in solid state feature \"Fermi arc\" states, connecting the\nsurface projections of the bulk chiral nodes. The surface Fermi arc is a\nsignature of nontrivial bulk topology. Unconventional chiral fermions with an\nextensive Fermi arc traversing the whole Brillouin zone have been theoretically\nproposed in CoSi. Here, we use scanning tunneling microscopy / spectroscopy to\ninvestigate quasiparticle interference at various terminations of a CoSi single\ncrystal. The observed surface states exhibit chiral fermion-originated\ncharacteristics. These reside on (001) and (011) but not (111) surfaces with\npi-rotation symmetry, spiral with energy, and disperse in a wide energy range\nfrom ~-200 to ~+400 mV. Owing to the high-energy and high-space resolution, a\nspin-orbit coupling-induced splitting of up to ~80 mV is identified. Our\nobservations are corroborated by density functional theory and provide strong\nevidence that CoSi hosts the unconventional chiral fermions and the extensive\nFermi arc states.",
        "positive": "New Generalized Informatics Framework for Development of Large Scale\n  Virtual Battery Material Databases: In this paper, we introduce an approach for the prediction of capacity for\nover 100,000 spinel compounds relevant for battery materials, from which we\npropose the 20 most promising candidate materials. In the design of batteries,\nselecting the proper material is difficult because there are so many metrics to\nconsider, including capacity which is a fundamental engineering property. Using\nreported experimental data as our starting point, we demonstrate how we can\nbuild a dataset that provides a guide for the selection of battery materials.\nAlthough we focus on capacity of Li based spinel structures for electrode\nmaterials relevant for usage in batteries, the methodology developed and\ndemonstrated here can be adapted to other properties, structures, and site\noccupancies. Further, theoretical capacity is often used as a guideline for\nmaterial design of battery materials. In this paper, we show how this is\ninsufficient for representing experimental measurements, while our methodology\ncloses this gap and provides an accurate computational representation of\nexperimental data."
    },
    {
        "anchor": "Electrically switchable Rashba-type Dzyaloshinskii-Moriya interaction\n  and skyrmion in two-dimensional magnetoelectric multiferroics: Realizing topological magnetism and its electric control are intensive topics\nin the spintronics due to their promising applications in information storage\nand logic technologies. Here we unveil that both can be achieved in the\ntwo-dimensional (2D) magnetoelectric multiferroics. Using first-principles\ncalculations, we show that strong Dzyaloshinskii-Moriya interaction (DMI),\nwhich is the key ingredient for the formation of exotic chiral magnetism, could\nbe induced in 2D multiferroics with vertical electric polarization via Rashba\neffect. We verify that such significant DMI can promote sub-10 nm skyrmion in\n2D multiferroics with perpendicular magnetic anisotropy such as CrN monolayer.\nIn addition, the presence of both magnetization and electric polarization in 2D\nmultiferroics provides us unique opportunity for the effective electric control\nof both strength and chirality of DMI and thereby the topological magnetism. As\nan example, we introduce the four multiferroic skyrmions with different\nchirality and polarity that can be manipulated by external field.",
        "positive": "Leveraging Plasmonic Hot Electrons to Quench Defect Emission in Metal --\n  Semiconductor Nanostructured Hybrids: Experiment and Modeling: Modeling light-matter interaction in hybrid plasmonic materials is vital to\ntheir widening relevance from optoelectronics to photocatalysis. Here, we\nexplore photoluminescence from ZnO nanorods (ZNR) embedded with gold\nnanoparticles (Au NPs). A progressive increase in Au NP concentration\nintroduces significant structural disorder and defects in the ZNRs, which\nparadoxically quenches defect related visible photoluminescence (PL) while\nintensifying the near band edge (NBE) emission. Under UV excitation, the\nsimulated semi-classical model realizes PL from ZnO with sub-band gap defect\nstates, eliciting visible emissions that are absorbed by Au NPs to generate a\nnon-equilibrium hot carrier distribution. The photo-stimulated hot carriers,\ntransferred to ZnO, substantially modify its steady-state luminescence,\nreducing NBE emission lifetime and altering the abundance of ionized defect\nstates, finally reducing visible emission. The simulations show that the change\nin the interfacial band bending at the Au-ZnO interface under optical\nillumination facilitates charge transfer between the components. This work\nprovides a general foundation to observe and model the hot carrier dynamics in\nhybrid plasmonic systems."
    },
    {
        "anchor": "Evaluation of excitation schemes for indirect detection of 14N via\n  solid-state HMQC NMR experiments: It has previously been shown that ${}^{14}$N NMR spectra can be reliably\nobtained through indirect detection via HMQC experiments. This method exploits\nthe transfer of coherence between single- (SQ) or double-quantum (DQ)\n${}^{14}$N coherences, and SQ coherences of a suitable spin-1/2 'spy' nucleus,\ne.g., ${}^1$H. It must be noted that SQ-SQ methods require a carefully\noptimized setup to minimize the broadening related to the first-order\nquadrupole interaction (i.e., an extremely well-adjusted magic angle and a\nhighly stable spinning speed), whereas DQ-SQ ones do not. In this work, the\nefficiencies of four ${}^{14}$N excitation schemes (DANTE, XiX, Hard Pulse\n(HP), and Selective Long Pulse (SLP)) are compared using J-HMQC based numerical\nsimulations and either SQ-SQ or DQ-SQ ${}^1$H-{${}^{14}$N} D-HMQC experiments\non L-histidine HCl and N-acetyl-L-valine at 18.8 T and 62.5 kHz MAS. The\nresults demonstrate that both DANTE and SLP provide a more efficient 14N\nexcitation profile than XiX and HP. Furthermore, it is shown that the SLP\nscheme: (i) is efficient over a large range of quadrupole interaction, (ii) is\nhighly robust to offset and rf-pulse length and amplitude, and (iii) is very\nsimple to set up. These factors make SLP ideally suited to widespread,\nnon-specialist use in solid-state NMR analyses of nitrogen-containing\nmaterials.",
        "positive": "Bending Deformation Driven by Molecular Rotation: In recent years, certain molecular crystals have been reported to possess\nsurprising flexibility by undergoing significant elastic or plastic deformation\nin response to mechanical loads. However, despite this experimental evidence,\nthere currently exists no atomistic mechanism to explain the physical origin of\nthis phenomenon from numerical simulations. In this study, we investigate the\nmechanical behavior of three naphthalene diimide derivatives, which serve as\nrepresentative examples, using direct molecular dynamics simulations. Our\nsimulation trajectory analysis suggests that molecular rotational freedom is\nthe key factor in determining a crystal's mechanical response, ranging from\nbrittle fracture to elastic or plastic deformation under mechanical bending.\nAdditionally, we propose a rotation-dependent potential energy surface as a\nmeans to classify organic materials' mechanical responses and identify new\ncandidates for future investigation."
    },
    {
        "anchor": "Current correlation functions for chemical sensors based on DNA\n  decorated carbon nanotube: The current characteristics of DNA decorated carbon nanotubes for different\ngas odors are studied. A simple model of charge transfer between the\nGas-DNA-base complex and single wall carbon nanotube (SWCN) is proposed to\nexplain the current response for different odors. The autocorrelation and\ntwo-point correlation functions are calculated for the current sensitivity\ncurves. These correlation functions together with the current characteristics\nform finger-prints for detection of the odor and DNA sequence.",
        "positive": "Indentation of solid membranes on rigid substrates with Van-der-Waals\n  attraction: We revisit the indentation of a thin solid sheet of size $R_{sheet}$\nsuspended on a circular hole of radius $R \\ll R_{sheet}$ in a smooth rigid\nsubstrate, addressing the effects of boundary conditions at the hole's edge.\nIntroducing a basic theoretical model for the Van-der-Waals (VdW)\nsheet-substrate attraction, we demonstrate the dramatic effect of replacing the\nclamping condition (Schwerin model) with a sliding condition, whereby the\nsupported part of the sheet is allowed to slide towards the indenter and relax\nthe induced hoop compression through angstrom-scale deflections from the\nthermodynamic equilibrium (determined by the VdW potential). We highlight the\npossibility that the indentation force $F$ may not exhibit the commonly\nanticipated cubic dependence on the indentation depth ($F\\propto \\delta^3$), in\nwhich the proportionality constant is governed by the sheet's stretching\nmodulus and the hole's radius $R$, but rather a {\\emph{pseduo-linear}}\nresponse, $F \\propto \\delta$, whereby the proportionality constant is governed\nby the bending modulus, the VdW attraction, and the sheet's size $R_{sheet} \\gg\nR$."
    },
    {
        "anchor": "Effect of chromophore-chromophore electrostatic interactions in the NLO\n  response of functionalized organic-inorganic sol-gel materials: In the last years, important non-linear optical results on sol-gel and\npolymeric materials have been reported, with values comparable to those found\nin crystals. These new materials contain push-pull chromophores either\nincorporated as guest in a high Tg polymeric matrix (doped polymers) or grafted\nonto the polymeric matrix. These systems present several advantages; however\nthey require significant improvement at the molecular level - by designing\noptimized chromophores with very large molecular figure of merit, specific to\neach application targeted. Besides, it was recently stated in polymers that the\nchromophore-chromophore electrostatic interactions, which are dependent of\nchromophore concentration, have a strong effect into their non-linear optical\nproperties. This has not been explored at all in sol-gel systems. In this work,\nthe sol-gel route was used to prepare hybrid organic-inorganic thin films with\ndifferent NLO chromophores grafted into the skeleton matrix. Combining a\nmolecular engineering strategy for getting a larger molecular figure of merit\nand by controlling the intermolecular dipole-dipole interactions through both:\nthe tuning of the push-pull chromophore concentration and the control of TEOS\n(Tetraethoxysilane) concentration, we have obtained a r33 coefficient around 15\npm/V at 633 nm for the classical DR1 azo-chromophore and a r33 around 50 pm/V\nat 831 nm for a new optimized chromophore structure.",
        "positive": "Bethe-Salpeter Equation Calculations of Core Excitation Spectra: We present a hybrid approach for GW/Bethe-Salpeter Equation (BSE)\ncalculations of core excitation spectra, including x-ray absorption (XAS),\nelectron energy loss spectra (EELS), and non-resonant inelastic x-ray\nscattering (NRIXS). The method is based on {\\it ab initio} wavefunctions from\nthe plane-wave pseudopotential code ABINIT; atomic core-level states and\nprojector augmented wave (PAW) transition matrix elements; the NIST core-level\nBSE solver; and a many-pole GW self-energy model to account for final-state\nbroadening and self-energy shifts. Multiplet effects are also accounted for.\nThe approach is implemented using an interface dubbed OCEAN (Obtaining Core\nExcitations using ABINIT and NBSE). To demonstrate the utility of the code we\npresent results for the K-edges in LiF as probed by XAS and NRIXS, the K-edges\nof KCl as probed by XAS, the Ti L_2,3-edge in SrTiO_3 as probed by XAS, and the\nMg L_2,3-edge in MgO as probed by XAS. We compare the results to experiments\nand results obtained using other theoretical approaches."
    },
    {
        "anchor": "In situ visualization of tip undercooling and lamellar microstructure\n  evolution of sea ice with manipulated orientation: Sea ice growth with lamellar microstructure containing brine channels has\nbeen extensively investigated. However, the quantitative growth information of\nsea ice remains lack due to the uncontrolled crystalline orientation in\nprevious investigations. For the first time, we in-situ observed the\nunidirectional growth of lamellar sea ice with well-manipulated ice crystal\norientation and visualized tip undercooling of sea ice. A semi-empirical model\nwas proposed to quantitatively address the variation of tip undercooling with\ngrowth velocity and salinity and compared with a very recent analytical model.\nWith the real-time observation, interesting phenomena of doublon tip in\ncellular ice growth and growth direction shift of ice dendritic tip were\ndiscovered for the first time, which are attributed to the complex solutal\ndiffusion and anisotropic interface kinetics in sea ice growth. The\nquantitative experiment provides a clear micro scenario of sea ice growth, and\nwill promote relevant investigations of sea ice in terms of the theoretical\napproach to describing the diffusion field around faceted ice dendritic tip.",
        "positive": "Evaluation of local stress state due to grain-boundary sliding during\n  creep within a crystal plasticity finite element multi-scale framework: Previous studies demonstrate that grain-boundary sliding could accelerate\ncreep rate and give rise to large internal stresses that can lead to damage\ndevelopment, e.g. formation of wedge cracks. The present study provides more\ninsight into the effects of grain-boundary sliding (GBS) on the deformation\nbehaviour of realistic polycrystalline aggregates during creep, through the\ndevelopment of a computational framework which combines: i) the use of\ninterface elements for sliding at grain boundaries, and ii) special triple\npoint (in 2D) or triple line (in 3D) elements to prevent artificial dilation at\nthese locations in the microstructure with iii) a physically-based crystal\nplasticity constitutive model for time-dependent inelastic deformation of the\nindividual grains. Experimental data at various scales is used to calibrate the\nframework and compare with model predictions. We pay particular consideration\nto effects of grain boundary sliding during creep of Type 316 stainless steel,\nwhich is used extensively in structural components of the UK fleet of Advanced\nGas Cooled Nuclear Reactors (AGRs). It is found that the anisotropic\ndeformation of the grains and the mismatch in crystallographic orientation\nbetween neighbouring grains play a significant role in determining the extent\nof sliding on a given boundary. Their effect on the development of stress\nwithin the grains, particularly at triple grain junctions, and the increase in\naxial stress along transverse boundaries are quantified. The article\ndemonstrates that the magnitude of the stress along the facets is\nhighly-dependent on the crystallographic orientations of the neighbouring\ngrains and the relative amount of sliding. Boundaries, transverse to the\napplied load tend to carry higher normal stresses of the order of 100-180 MPa,\nin cases where the neighbouring grains consist of plastically-harder\ncrystallographic orientations."
    },
    {
        "anchor": "Partial Order-Disorder Transition Driving Closure of Band Gap: Example\n  of Thermoelectric Clathrates: On the quest for efficient thermoelectrics, semiconducting behavior is a\ntargeted property. Yet, this is often difficult to achieve due to the complex\ninterplay between electronic structure, temperature, and disorder. We find this\nto be the case for the thermoelectric clathrate Ba$_8$Al$_{16}$Si$_{30}$:\nAlthough this material exhibits a band gap in its groundstate, a\ntemperature-driven partial order-disorder transition leads to its effective\nclosing. This finding is enabled by a novel approach to calculate the\ntemperature-dependent effective band structure of alloys. Our method fully\naccounts for the effects of short-range order and can be applied to complex\nalloys with many atoms in the primitive cell, without relying on effective\nmedium approximations.",
        "positive": "Pressure-induced transition from the dynamic to static Jahn-Teller\n  effect in (Ph$_{4}$P)$_{2}$IC$_{60}$: High-pressure infrared transmission measurements on \\PhC60 were performed up\nto 9 GPa over a broad frequency range (200 - 20000 cm$^{-1}$) to monitor the\nvibrational and electronic/vibronic excitations under pressure. The four\nfundamental T$_{1u}$ modes of \\C60a\\ are split into doublets already at the\nlowest applied pressure and harden with increasing pressure. Several cation\nmodes and fullerene-related modes split into doublets at around 2 GPa, the most\nprominent one being the G$_{1u}$ mode. The splitting of the vibrational modes\ncan be attributed to the transition from the dynamic to static Jahn-Teller\neffect, caused by steric crowding at high pressure. Four absorption bands are\nobserved in the NIR-VIS frequency range. They are discussed in terms of\ntransitions between LUMO electronic states in \\C60a, which are split because of\nthe Jahn-Teller distortion and can be coupled with vibrational modes. Various\ndistortions and the corresponding symmetry lowering are discussed. The observed\nredshift of the absorption bands indicates that the splitting of the LUMO\nelectronic states is reduced upon pressure application."
    },
    {
        "anchor": "Softened sp2-sp3 bonding network leads to strong anharmonicity and weak\n  hydrodynamics in graphene+: Graphene+, a novel carbon monolayer with sp2-sp3 hybridization, is recently\nreported to exhibit graphene-like Dirac properties and unprecedented\nout-of-plane half-auxetic behavior [Yu et al, Cell Reports Physical Science, 3\n100790 (2022)]. Herein, from comprehensively state-of-the-art first-principles\nstudies, we report the exceptional lattice thermal transport properties of\ngraphene+ driven by the unique sp2-sp3 crystal configuration. At room\ntemperature, the thermal conductivity of graphene+ is calculated to be ~170\nW/mK, which is much lower than that of graphene (~3170 W/mK) Despite the\nbuckling structure, weak phonon scattering phase space is trapped in graphene+.\nThus, the reduction in thermal conductivity magnitude stems from soft bonding\ndue to the unique sp2-sp3 crystal configuration. Soft bonding suppresses the\nvibrations of acoustic phonons, which leads to strong anharmonicity and weak\nphonon hydrodynamics. Further, lower group velocity, relaxation time and\nsmaller phonon mean free path emerge in graphene+, and the significantly\ndecreased thermal conductivity is achieved. Our study provides fundamental\nphysical insights into the thermal transport properties of graphene+, and it\nserves as an ideal model to study atomic bonding versus thermal transport\nproperties due to weak scattering phase space.",
        "positive": "Steric hindrance in the on-surface synthesis of diethynyl-linked\n  anthracene polymers: Hybrid sp-sp2 structures can be efficiently obtained on metal substrates via\non-surface synthesis. The choice of both the precursor and of the substrate\nimpacts on the effectiveness of the process and the stability of the formed\nstructures. Here we demonstrate that using anthracene-based molecules as\nprecursor, the formation on Au(111) of polymers hosting sp carbon chains is\naffected by the steric hindrance between aromatic groups. In particular, by\nscanning tunneling microscopy and density functional theory calculations we\nshow that the de-metalation of organometallic structures induces a lateral\nseparation of adjacent polymers preventing the formation of ordered domains."
    },
    {
        "anchor": "On the Rabinowicz like criterion of formation of wear particles in a\n  system with a soft surface layer: In 1958, Ernest Rabinowicz suggested a simple criterion distinguishing the\nregimes of plastic smoothing and formation of wear particles in a contact of\nhomogeneous sliding bodies. However, he did not consider any detailed mechanism\nof either plastic smoothing or debris formation. In a recent paper in Nature\nCommunications, Molinari et al. have confirmed the criterion using explicit\nmesoparticle simulation. The work of Molinari's group provides a strong support\nto the general concept of Rabinowicz which is based on the consideration of\ncompetition of plastic deformation and fracture. It is interesting to apply\nthis concept to more general configurations than those considered by Rabinowicz\nand Molinari's group. An important case is a system having a very soft surface\nlayer. In the present paper, the analysis similar to that of Rabinowicz is\napplied to materials with soft layer. It is shown that in this case, too, both\ncases of plastic deformation and debris formation may occur. It would be\ninteresting to verify this prediction by explicit meso-particle simulations\nsimilar to those of Molinari's group.",
        "positive": "Shock Wave Evolution into Strain Solitary Wave in Nonlinearly Elastic\n  Solid Bar: In this paper we present thorough experimental observation of the process of\nshock wave transformation into a bulk strain solitary wave in a nonlinearly\nelastic solid bar made of polystyrene. A theoretical model based on the\ndescribing propagation of a plane elastic wave in a bar is developed with\naccount made for material nonlinearity and viscosity. Numerical modeling\nperformed on the base of the developed model with and without regard to\nviscosity demonstrated formation of a long stable disturbance at proper account\nmade for viscoelastic properties of the bar material."
    },
    {
        "anchor": "Optical spectroscopy of two-dimensional layered\n  $(C_{6}H_{5}C_{2}H_{4}-NH_{3})_{2}-PbI_{4}$ perovskite: We report on optical spectroscopy (photoluminescence and photoluminescence\nexcitation) on two-dimensional self-organized layers of\n$(C_{6}H_{5}C_{2}H_{4}-NH_{3})_{2}PbI_{4}$ perovskite. Temperature and\nexcitation power dependance of the optical spectra gives a new insight into the\nexcitonic and phononic properties of this hybrid organic/inorganic\nsemiconductor. In particular, exciton-phonon interaction is found to be more\nthan one order of magnitude higher than in GaAs QWs. As a result,\nphotoluminescence emission lines have to be interpreted in the framework of a\npolaron model.",
        "positive": "Emergent Spiking in Non-Ideal Memristor Networks: Memristors have uses as artificial synapses and perform well in this role in\nsimulations with artificial spiking neurons. Our experiments show that\nmemristor networks natively spike and can exhibit emergent oscillations and\nbursting spikes. Networks of near-ideal memristors exhibit behaviour similar to\na single memristor and combine in circuits like resistors do. Spiking is more\nlikely when filamentary memristors are used or the circuits have a higher\ndegree of compositional complexity (i.e. a larger number of anti-series or\nanti-parallel interactions). 3-memristor circuits with the same memristor\npolarity (low compositional complexity) are stabilised and do not show spiking\nbehaviour. 3-memristor circuits with anti-series and/or anti-parallel\ncompositions show richer and more complex dynamics than 2-memristor spiking\ncircuits. We show that the complexity of these dynamics can be quantified by\ncalculating (using partial auto-correlation functions) the minimum order\nauto-regression function that could fit it. We propose that these oscillations\nand spikes may be similar phenomena to brainwaves and neural spike trains and\nsuggest that these behaviours can be used to perform neuromorphic computation."
    },
    {
        "anchor": "Coupling phenomena and collective effects in resonant meta-molecules\n  supporting plasmonic and magnetic functionalities: a review: We review both the fundamental aspects and the applications of functional\nmagneto-optic and opto-magnetic metamaterials displaying collective and\ncoupling effects on the nanoscale, where the concepts of optics and magnetism\nmerge to produce unconventional phenomena. The use of magnetic materials\ninstead of the usual noble metals allows for an additional degree of freedom\nfor the control of electromagnetic field properties, as well as it allows light\nto interact with the spins of the electrons and to actively manipulate the\nmagnetic properties of such nanomaterials. In this context, we explore the\nconcepts of near-field coupling of plasmon modes in magnetic meta-molecules, as\nwell as the effect of excitation of surface lattice resonances in\nmagneto-plasmonic crystals. Moreover, we discuss how these coupling effects can\nbe exploited to artificially enhance optical magnetism in plasmonic\nmeta-molecules and crystals. Finally, we highlight some of the present\nchallenges and provide a perspective on future directions of the research\ntowards photon-driven fast and efficient nanotechnologies bridging magnetism\nand optics beyond current limits.",
        "positive": "Surface buckling of phosphorene materials: determination, origin and\n  influence on electronic structure: The surface structure of phosphorene crystals materials is determined using\nsurface sensitive dynamical micro-spot low energy electron diffraction\n({\\mu}LEED) analysis using a high spatial resolution low energy electron\nmicroscopy (LEEM) system. Samples of (\\textit{i}) crystalline cleaved black\nphosphorus (BP) at 300 K and (\\textit{ii}) exfoliated few-layer phosphorene\n(FLP) of about 10 nm thicknes, which were annealed at 573 K in vacuum were\nstudied. In both samples, a significant surface buckling of 0.22 {\\AA} and 0.30\n{\\AA}, respectively, is measured, which is one order of magnitude larger than\npreviously reported. Using first principle calculations, the presence of\nsurface vacancies is attributed not only to the surface buckling in BP and FLP,\nbut also the previously reported intrinsic hole doping of phosphorene\nmaterials."
    },
    {
        "anchor": "Excitonic nonlinear absorption in CdS nanocrystals studied using Z-scan\n  technique: Irradiance dependence of excitonic nonlinear absorption in Cadmium Sulfide\n(CdS) nanocrystals has been studied by using Z-scan method with nanosecond\nlaser pulses. The wavelength dependence of nonlinear absorption has also been\nmeasured near the excitonic transition of 1S(e)-1S3/2(h). We observe the\nsaturable absorption, which can be described by a third-order and a fifth-order\nnonlinear process for both 3.0-nm-sized and 2.3-nm-sized CdS nanocrystals. The\nexperimental results show that the excitonic nonlinear absorption of CdS\nnanocrystals is greatly enhanced with decreasing particle size. A two-level\nmodel is utilized to explain both irradiance and wavelength dependence of the\nexcitonic nonlinearity.",
        "positive": "Spatial ordering of nano-dislocation loops in ion-irradiated materials: Defect microstructures formed in ion-irradiated metals, for example iron or\ntungsten, often exhibit patterns of spatially ordered nano-scale dislocation\nloops. We show that such ordered dislocation loop structures may form\nspontaneously as a result of Brownian motion of loops, biased by the\nangular-dependent elastic interaction between the loops. Patterns of spatially\nordered loops form once the local density of loops produced by ion irradiation\nexceeds a critical threshold value."
    },
    {
        "anchor": "Structural and thermal transport properties of ferroelectric domain\n  walls in GeTe from first principles: Ferroelectric domain walls are boundaries between regions with different\npolarization orientations in a ferroelectric material. Using first principles\ncalculations, we characterize all different types of domain walls forming on\n($11\\bar{1}$), ($111$) and ($1\\bar{1}0$) crystallographic planes in\nthermoelectric GeTe. We find large structural distortions in the vicinity of\nmost of these domain walls, which are driven by polarization variations. We\nshow that such strong strain-order parameter coupling will considerably reduce\nthe lattice thermal conductivity of GeTe samples containing domain walls with\nrespect to single crystal. Our results thus suggest that domain engineering is\na promising path for enhancing the thermoelectric figure of merit of GeTe.",
        "positive": "Understanding Transient Photoluminescence in Halide Perovskite Layer\n  Stacks and Solar Cells: While transient photoluminescence measurements are a very popular tool to\nmonitor the charge-carrier dynamics in the field of halide perovskite\nphotovoltaics, interpretation of data obtained on multilayer samples is highly\nchallenging due to the superposition of various effects that modulate the\ncharge-carrier concentration in the perovskite layer and thereby the measured\nPL. These effects include bulk and interfacial recombination, charge transfer\nto electron or hole transport layers and capacitive charging or discharging.\nHere, numerical simulations with Sentauraus TCAD, analytical solutions and\nexperimental data with a dynamic range of ~7 orders of magnitude on a variety\nof different sample geometries from perovskite films on glass to full devices\nare combined to present an improved understanding of this method. A\npresentation of the decay time of the TPL decay that follows from taking the\nderivative of the photoluminescence at every time is proposed. Plotting this\ndecay time as a function of the time-dependent quasi-Fermi level splitting\nenables distinguishing between the different contributions of radiative and\nnon-radiative recombination as well as charge extraction and capacitive effects\nto the decay."
    },
    {
        "anchor": "Relation between resistance drift and optical gap in phase change\n  materials: The optical contrast in a phase change material is concomitant with its\nstructural transition. We connect these two by first recognizing that Friedel\noscillations couple electrons propagating in opposite directions and supply an\nadditional Coulomb energy. As the crystal switches phase, this energy acquires\ntime dependence and the Landau-Zener mechanism operates, steering population\ntransfer from the valence to the conduction band and vice versa. Spectroscopy\nsuggests that the oscillator energy dominates the optical properties and a\ncalculation involving the crystalline field and spin-orbit interaction yields\ngood estimates for of both structural phases. Further analysis relates the\noptical gap with the crystalline-field energy as well as activation energy for\nelectrical conduction. This last property characterizes the amorphous phase,\nthereby furnishing a link between the crystalline field and the activation\nenergy and ultimately with the resistance drift exponent. Providing optical\nmeans to quantify resistance drift in PCMs could circumvent the need for\nfabricating expensive devices and performing time consuming measurements.",
        "positive": "Room temperature self-assembly of mixed nanoparticles into complex\n  material systems and devices: The ability to manufacture nanomaterials with complex and structured\ncomposition using otherwise incompatible materials increasingly underpins the\nnext generation of technologies. This is translating into growing efforts\nintegrating a wider range of materials onto key technology platforms1 - in\nphotonics, one such platform is silica, a passive, low loss and robust medium\ncrucial for efficient optical transport2. Active functionalisation, either\nthrough added gain or nonlinearity, is mostly possible through the integration\nof active materials3, 4. The high temperatures used in manufacturing of silica\nwaveguides, unfortunately, make it impossible to presently integrate many\norganic and inorganic species critical to achieving this extended\nfunctionality. Here, we demonstrate the fabrication of novel waveguides and\ndevices made up of complex silica based materials using the self-assembly of\nnanoparticles. In particular, the room temperature fabrication of silica\nmicrowires integrated with organic dyes (Rhodamine B) and single photon\nemitting nanodiamonds is presented."
    },
    {
        "anchor": "Nanoscale electronic transparency of wafer-scale hexagonal boron nitride: Monolayer hBN has attracted interest as a potentially weakly interacting 2D\ninsulating layer in heterostructures. Recently, wafer-scale hBN growth on\nCu(111) has been demonstrated for semiconductor chip fabrication processes and\ntransistor action. For all these applications, the perturbation on the\nunderlying electronically active layers is critical. For example, while hBN on\nCu(111) has been shown to preserve the Cu(111) surface state 2D electron gas,\nit was previously unknown how this varies over the sample and how it is\naffected by local electronic corrugation. Here, we demonstrate that the Cu(111)\nsurface state under wafer-scale hBN is robustly homogeneous in energy and\nspectral weight over nanometer length scales and over atomic terraces. We\ncontrast this with a benchmark spectral feature associated with interaction\nbetween BN atoms and the Cu surface, which varies with the Moir\\'e pattern of\nthe hBN/Cu(111) sample and is dependent on atomic registry. This work\ndemonstrates that fragile 2D electron systems and interface states are largely\nunperturbed by local variations created by the hBN due to atomic-scale\ninteractions with the substrate, thus providing a remarkably transparent window\non low-energy electronic structure below the hBN monolayer.",
        "positive": "Extrinsic electromagnetic chirality in all-photodesigned one-dimensional\n  THz metamaterials: We suggest that all-photodesigned metamaterials, sub-wavelength custom\npatterns of photo-excited carriers on a semiconductor, can display an exotic\nextrinsic electromagnetic chirality in terahertz (THz) frequency range. We\nconsider a photo-induced pattern exhibiting 1D geometrical chirality, i.e. its\nmirror image can not be superposed onto itself by translations without\nrotations and, in the long wavelength limit, we evaluate its bianisotropic\nresponse. The photo-induced extrinsic chirality turns out to be fully\nreconfigurable by recasting the optical illumination which supports the\nphoto-excited carriers. The all-photodesigning technique represents a feasible,\neasy and powerful method for achieving effective matter functionalization and,\ncombined with the chiral asymmetry, it could be the platform for a new\ngeneration of reconfigurable devices for THz wave polarization manipulation."
    },
    {
        "anchor": "Marrying excitons and plasmons in monolayer transition-metal\n  dichalcogenides: Just as photons are the quanta of light, plasmons are the quanta of\norchestrated charge-density oscillations in conducting media. Plasmon phenomena\nin normal metals, superconductors and doped semiconductors are often driven by\nlong-wavelength Coulomb interactions. However, in crystals whose Fermi surface\nis comprised of disconnected pockets in the Brillouin zone, collective electron\nexcitations can also attain a shortwave component when electrons transition\nbetween these pockets. Here, we show that the band structure of monolayer\ntransition-metal dichalcogenides gives rise to an intriguing mechanism through\nwhich shortwave plasmons are paired up with excitons. The coupling elucidates\nthe origin for the optical side band that is observed repeatedly in monolayers\nof WSe$_2$ and WS$_2$ but not understood. The theory makes it clear why\nexciton-plasmon coupling has the right conditions to manifest itself distinctly\nonly in the optical spectra of electron-doped tungsten-based monolayers.",
        "positive": "Growth of flat SrRuO3(111) thin films suitable as bottom electrodes in\n  heterostructures: Thin film growth of ferroelectric or multiferroic materials on SrTiO3(111)\nwith a buffer electrode has been hampered by the difficulty of growing flat\nelectrodes on this polar orientation. We report on the growth and\ncharacterization of SrRuO3 thin films deposited by pulsed laser deposition on\nSrTiO3(111). We show that our SrRuO3(111) films are epitaxial and display\nmagnetic bulk-like properties. Films presenting a thickness between 20 and 30nm\nare found to be very flat (with an RMS of about 0.5 nm) and therefore suitable\nas bottom electrodes in heterostructures."
    },
    {
        "anchor": "The wavefunction reconstruction effects in calculation of DM-induced\n  electronic transition in semiconductor targets: The physics of the electronic excitation in semiconductors induced by sub-GeV\ndark matter (DM) have been extensively discussed in literature, under the\nframework of the standard plane wave (PW) and pseudopotential calculation\nscheme. In this paper, we investigate the implication of the all-electron (AE)\nreconstruction on estimation of the DM-induced electronic transition event\nrates. As a benchmark study, we first calculate the wavefunctions in silicon\nand germanium bulk crystals based on both the AE and pseudo (PS) schemes within\nthe projector augmented wave (PAW) framework, and then make comparisons between\nthe calculated excitation event rates obtained from these two approaches. It\nturns out that in process where large momentum transfer is kinetically allowed,\nthe two calculated event rates can differ by a factor of a few. Such\ndiscrepancies are found to stem from the high-momentum components neglected in\nthe PS scheme. It is thus implied that the correction from the AE wavefunction\nin the core region is necessary for an accurate estimate of the DM-induced\ntransition event rate in semiconductors.",
        "positive": "Accelerating computational materials discovery with artificial\n  intelligence and cloud high-performance computing: from large-scale screening\n  to experimental validation: High-throughput computational materials discovery has promised significant\nacceleration of the design and discovery of new materials for many years.\nDespite a surge in interest and activity, the constraints imposed by\nlarge-scale computational resources present a significant bottleneck.\nFurthermore, examples of large-scale computational discovery carried through\nexperimental validation remain scarce, especially for materials with product\napplicability. Here we demonstrate how this vision became reality by first\ncombining state-of-the-art artificial intelligence (AI) models and traditional\nphysics-based models on cloud high-performance computing (HPC) resources to\nquickly navigate through more than 32 million candidates and predict around\nhalf a million potentially stable materials. By focusing on solid-state\nelectrolytes for battery applications, our discovery pipeline further\nidentified 18 promising candidates with new compositions and rediscovered a\ndecade's worth of collective knowledge in the field as a byproduct. By\nemploying around one thousand virtual machines (VMs) in the cloud, this process\ntook less than 80 hours. We then synthesized and experimentally characterized\nthe structures and conductivities of our top candidates, the\nNa$_x$Li$_{3-x}$YCl$_6$ ($0 < x < 3$) series, demonstrating the potential of\nthese compounds to serve as solid electrolytes. Additional candidate materials\nthat are currently under experimental investigation could offer more examples\nof the computational discovery of new phases of Li- and Na-conducting solid\nelectrolytes. We believe that this unprecedented approach of synergistically\nintegrating AI models and cloud HPC not only accelerates materials discovery\nbut also showcases the potency of AI-guided experimentation in unlocking\ntransformative scientific breakthroughs with real-world applications."
    },
    {
        "anchor": "DFT Investigation of Biocatalytic Mechanisms from pH-Driven,\n  Multi-Enzyme, Biomimetic Behavior in CeO2: There is considerable interest in the pH-dependent, switchable, biocatalytic\nproperties of cerium oxide (CeO2) nanoparticles (CeNPs) in biomedicine, where\nthese materials exhibit beneficial antioxidant activity against reactive oxygen\nspecies (ROS) at basic physiological pH but cytotoxic prooxidant activity in\nacidic cancer cell pH microenvironment. While the general characteristics of\nthe role of oxygen vacancies are known, the mechanism of their action at the\natomic scale under different pH conditions has yet to be elucidated. The\npresent work applies density functional theory (DFT) calculations to interpret,\nat the atomic scale, the pH-induced behavior of the stable {111} surface of\nCeO2 containing oxygen vacancies. Analysis of the surface-adsorbed media\nspecies reveals the critical role of pH on the interaction between ROS and the\ndefective CeO2 {111} surface. Under basic conditions, the superoxide dismutase\n(SOD) and catalase (CAT) biomimetic reactions can be performed cyclically,\nscavenging and decomposing ROS to harmless products, making CeO2 an excellent\nantioxidant. However, under acidic conditions, the CAT biomimetic reaction is\nhindered owing to the limited reversibility of Ce3+ and Ce4+ and formation and\nannihilation of oxygen vacancies. A Fenton biomimetic reaction is predicted to\noccur simultaneously with the SOD and CAT biomimetic reactions, resulting in\nthe formation of hydroxyl radicals, making CeO2 a cytotoxic prooxidant.",
        "positive": "Adsorption of Hydrogen in Graphene without Band Gap Opening at the Dirac\n  Point: The band gap of periodically-doped graphene with hydrogen is investigated. It\nis found through a tight-binding model (TB) that for certain periodicities,\ncalled here NGPs (non-gap periodicities), no gap is opened at the Dirac point.\nThis result is confirmed by Density Functional Theory (DFT) calculations. DFT\nresults show that a tiny gap is opened for NGPs due to exchange effects, not\ntaken into account in the TB model. However, this tiny gap is one or two orders\nof magnitude smaller than the gap opened for other periodicities different from\nNGPs. This finding opens up a new path for band gap engineering experiments in\ngraphene."
    },
    {
        "anchor": "First principles investigation of high thermal conductivity in hexagonal\n  boron phosphide: Designing and searching for high lattice thermal conductivity materials in\nboth bulk and nanoscale level is highly demanding for electronics cooling.\nBoron phosphide is a III-V compound semiconductor with superior structural and\nthermal properties. In this work, we studied the lattice thermal conductivity\nof hexagonal boron phosphide(h-BP) using first principles calculations. For\npure h-BP, we found a high lattice thermal conductivity (at 300K) of 561.2\nWm-1K-1 and 427.4 Wm-1K-1 along a-axis and c-axis respectively. These values\nare almost equal to hexagonal silicon carbide(2H-SiC) and cubic boron\nphosphide(c-BP). We also computed the length dependence thermal conductivity\nfor its applications in nanostructures. At nanoscale (L=100 nm), a high thermal\nconductivity of ~71.5 Wm-1K-1(56.2 Wm-1K-1) is observed along a-axis(c-axis).\nThis result suggests that, h-BP will be a promising material for thermal\nmanagement applications in micro/nano electronics.",
        "positive": "van der Waals forces control the internal chemical structure of\n  monolayers within ABP2X6 lamellar materials: Following the recent demonstration that van der Waals forces control the\nferroelectric ordering of layers within nanoflakes and bulk samples of\nCuBiP2Se6 and CuInP2S6, it is demonstrated that they also control the internal\ngeometrical structure of isolated monolayers of these materials. This internal\nstructure involves large displacements of the copper atoms, either normal to\nthe layer plane or else within the plane, that change its ligation environment.\nIn both cases, the van der Waals dispersion force out-competes traditional\nbonding effects to control structure. However, we find that the aspects of the\ndispersion force giving rise to each effect are uncorrelated: long range\neffects control inter-layer ferroelectric ordering whereas short-range effects\ncontrol internal layer structure. These conclusions are drawn considering\npredicted properties of monolayers, bilayers, and bulk materials obtained using\n14 density-functional-theory based methods. While the different methods used\noften predict starkly different quantitative results, they concur as to the\nbasic nature of ABP2X6 materials. Of the methods used, only the PBE-D3 and\noptPBEvdW methods were found to predict a wide range of observed properties\nwithout serious disparity. Finding optimal computational methods remains a\nsignificant challenge for which the unusual multi-scale nature of the van der\nWaals interactions in ABP2X6 materials provides demanding criteria."
    },
    {
        "anchor": "Influential Functionals: Learning about density functional approximations (DFAs), or approximations\nfor the exchange-correlation functional, can be intimidating. Density\nFunctional Theory is now one of the primary simulation tools for the practicing\nchemist or materials scientist, and its accuracy relies upon an appropriate\nchoice of DFA. Over the past decades, there has been extensive research effort\nto find better DFAs, and there is now a large body of literature to read\nthrough for someone learning about DFAs for the first time. In this brief\nreport, I share an analysis that suggests which functionals and publications\nhave been the most influential, as a potential reading list to new scientists\nin this area. Here, \"influential\" is defined as \"likely to have informed the\ndesign of another functional,\" and not simply a measure of number of citations,\nor how much that functional has been used for practical applications. This\nanalysis is not claimed to be complete.",
        "positive": "Compressed Sensing of Compton Profiles for Fermi Surface Reconstruction:\n  Concept and Implementation: Compton scattering is a well-established technique that can provide detailed\ninformation about electronic states in solids. Making use of the principle of\ntomography, it is possible to determine the Fermi surface from sets of\nCompton-scattering data with different scattering axes. Practical applications,\nhowever, are limited due to long acquisition time required for measuring along\nenough number of scattering directions. Here, we propose to overcome this\ndifficulty using compressed sensing. Taking advantage of a hidden sparsity in\nthe momentum distribution, we are able to reconstruct the three-dimensional\nmomentum distribution of bcc-Li, and identify the Fermi surface with as little\nas 14 directions of scattering data with unprecedented accuracy. This\ncompressed-sensing approach will permit further wider applications of the\nCompton scattering experiments."
    },
    {
        "anchor": "Combinatorial approach to bulk detector material engineering:\n  Application to rapid NaI performance optimization via multi-element\n  doping/co-doping strategy: Historically, the discovery and optimization of doped bulk materials has been\npredominantly developed through an Edisonian approach. While successful and\ndespite the constant progress in fundamental understanding of detector\nmaterials physics, the process has been restricted by its inherent slow pace\nand low success rate. This poor throughput owes largely to the considerable\ncompositional space that needs to be accounted for to fully comprehend complex\nmaterial/performance relationship. Here, we present a combinatorial approach\nwhere doped bulk scintillator materials can be rapidly optimized for their\nproperties through concurrent extrinsic doping/co-doping strategies. The\nconcept that makes use of Design of Experiment, rapid growth and evaluation\ntechniques, and multivariable regression analysis, has been successfully\napplied to the engineering of NaI performance, a historical but mediocre\nperformer in scintillation detection. Using this approach, we identified a\nthree-element doping/co-doping strategy that significantly improves the\nmaterial performance. The composition was uncovered by simultaneously screening\nfor a beneficial co-dopant ion among the alkaline earth metal family and by\noptimizing its concentration and that of Tl+ and Eu2+ ions. The composition\nwith the best performance was identified as 0.1% mol Tl+, 0.1% mol Eu2+ and\n0.2% mol Ca2+. This formulation shows enhancement of energy resolution and\nlight output at 662 keV, from 6.3 to 4.9%, and from 44,000 to 52,000 ph/MeV,\nrespectively. The method, in addition to improving NaI performance, provides a\nversatile framework for rapidly unveiling complex and concealed correlations\nbetween material composition and performance, and should be broadly applicable\nto optimization of other material properties.",
        "positive": "Insights and challenges of applying the $GW$ method to transition metal\n  oxides: The ab initio $GW$ method is considered as the most accurate approach for\ncalculating the band gaps of semiconductors and insulators. Yet its application\nto transition metal oxides (TMOs) has been hindered by the failure of\ntraditional approximations developed for conventional semiconductors. In this\nwork, we examine the effects of these approximations on the values of band gaps\nfor ZnO, Cu$_2$O, and TiO$_2$. In particular, we explore the origin of the\ndifferences between the two widely used plasmon-pole models. Based on the\ncomparison of our results with the experimental data and previously published\ncalculations, we discuss which approximations are suitable for TMOs and why."
    },
    {
        "anchor": "Terahertz control of photoluminescence emission in few-layer InSe: A promising route for the development of opto-elelctronic technology is to\nuse terahertz radiation to modulate the optical properties of semiconductors.\nHere we demonstrate the dynamical control of photoluminescence (PL) emission in\nfew-layer InSe using picosecond terahertz pulses. We observe a strong PL\nquenching (up to 50%) after the arrival of the terahertz pulse followed by a\nreversible recovery of the emission on the time scale of 50ps at T =10K.\nMicroscopic calculations reveal that the origin of the photoluminescence\nquenching is the terahertz absorption by photo-excited carriers: this leads to\na heating of the carriers and a broadening of their distribution, which reduces\nthe probability of bimolecular electron-hole recombination and, therefore, the\nluminescence. By numerically evaluating the Boltzmann equation, we are able to\nclarify the individual roles of optical and acoustic phonons in the subsequent\ncooling process. The same PL quenchingmechanismis expected in other van\nderWaals semiconductors and the effectwill be particularly strong for materials\nwith low carrier masses and long carrier relaxation time, which is the case for\nInSe. This work gives a solid background for the development of opto-electronic\napplications based on InSe, such as THz detectors and optical modulators.",
        "positive": "Structure, stability, and mobility of small Pd clusters on the\n  stoichiometric and defective TiO$_2$ (110) surfaces: We report on the structure and adsorption properties of Pd$_n$ ($n=1-4$)\nclusters supported on the rutile TiO$_2$ (110) surfaces with the possible\npresence of a surface oxygen vacancy or a subsurface Ti-interstitial atom. As\npredicted by the density functional theory, small Pd clusters prefer to bind to\nthe stoichiometric titania surface or at sites near subsurface Ti-interstitial\natoms. The adsorption of Pd clusters changes the electronic structure of the\nunderlying surface. For the surface with an oxygen vacancy, the charge\nlocalization and ferromagnetic spin states are found to be largely attenuated\nowing to the adsorption of Pd clusters. The potential energy surfaces of the Pd\nmonomer on different types of surfaces are also reported. The process of\nsintering is then simulated via the Metropolis Monte Carlo method. The presence\nof oxygen vacancy likely leads to the dissociation of Pd clusters. On the\nstoichiometric surface or surface with Ti-interstitial atom, the Pd monomers\ntend to sinter into larger clusters, whereas the Pd dimer, trimer and tetramer\nappear to be relatively stable below 600 K. This result agrees with the\nstandard sintering model of transition metal clusters and experimental\nobservations."
    },
    {
        "anchor": "Resolving the intrinsic short-range ordering of K$^+$ ions on cleaved\n  muscovite mica: Muscovite mica, KAl$_2$(Si$_3$Al)O$_{10}$(OH)$_2$, is a common layered\nphyllosilicate with perfect cleavage planes. The atomically flat surfaces\nobtained through cleaving lend themselves to scanning probe techniques with\natomic resolution and are ideal to model minerals and clays. Despite the\nimportance of the cleaved mica surfaces, several questions remain unresolved.\nIt is established that K$^+$ ions decorate the cleaved surface, but their\nintrinsic ordering -- unaffected by the interaction with the environment -- is\nnot known. This work presents clear images of the K$^+$ distribution of cleaved\nmica obtained with low-temperature non-contact atomic force microscopy (AFM)\nunder ultra-high vacuum (UHV) conditions. The data unveil the presence of\nshort-range ordering, contrasting previous assumptions of random or fully\nordered distributions. Density functional theory (DFT) calculations and Monte\nCarlo simulations show that the substitutional subsurface Al$^{3+}$ ions have\nan important role for the surface K$^+$ ion arrangement.",
        "positive": "Broadband dielectric microwave microscopy on $\u03bc$m length scales: We demonstrate that a near-field microwave microscope based on a transmission\nline resonator allows imaging in a substantially wide range of frequencies, so\nthat the microscope properties approach those of a spatially-resolved impedance\nanalyzer. In the case of an electric probe, the broadband imaging can be used\nin a direct fashion to separate contributions from capacitive and resistive\nproperties of a sample at length scales on the order of one micron. Using a\nmicrowave near-field microscope based on a transmission line resonator we\nimaged the local dielectric properties of a Focused Ion Beam (FIB) milled\nstructure on a high-dielectric-constant Ba_{0.6}Sr_{0.4}TiO_3 (BSTO) thin film\nin the frequency range from 1.3 GHz to 17.4 GHz. The electrostatic\napproximation breaks down already at frequencies above ~10 GHz for the probe\ngeometry used, and a full-wave analysis is necessary to obtain qualitative\ninformation from the images."
    },
    {
        "anchor": "Dislocation drag and its influence on elastic precursor decay: Plastic deformation is mediated by the creation and movement of dislocations,\nand at high stress the latter is dominated by dislocation drag from phonon\nwind. By simulating a 1-D shock impact problem we analyze the importance of\naccurately modeling dislocation drag and dislocation density evolution in the\nhigh stress regime. Dislocation drag is modeled according to a first-principles\nderivation as a function of stress and dislocation character, and its\ntemperature and density dependence are approximated to the extent currently\nknown. Much less is known about dislocation density evolution, leading to far\ngreater uncertainty in these model parameters. In studying anisotropic fcc\nmetals with character dependent dislocations, the present work generalizes\nsimilar earlier studies by other authors.",
        "positive": "Structure determination of liquid carbon tetrabromide via a combination\n  of x-ray and neutron diffraction data and reverse Monte Carlo modeling: In order to reveal the atomic level structure of liquid carbon tetrabromide,\na new synchrotron x-ray diffraction measurement, over a wide momentum transfer\n(Q-)range, has been performed. These x-ray data have been interpreted together\nwith a neutron diffraction dataset, measured earlier, using the reverse Monte\nCarlo method. The structure is analysed on the basis of partial radial\ndistribution functions and distance dependent orientational correlation\nfunctions. Orientational correlations behave similarly to other carbon\ntetrahalides. Moreover, the information content of the new x-ray diffraction\ndata set, and in particular, of the varying Q-range, is also discussed.\n  Only very small differences have been found between results of calculations\nthat apply one single experimental structure factor and the ones that use both\nx-ray and neutron diffraction data: the latter showed slightly more ordered\ncarbon-carbon radial distribution function, which resulted in seemingly more\nordered orientational correlations between pairs of molecules. Neither the\nextended Q-range, nor the application of local invariance constraints yielded\nsignificant new information. For providing a simple reference system, a hard\nsphere model has also been created that can describe most of the partial radial\ndistribution functions and orientational correlations of the real system at a\nsemi-quantitative level."
    },
    {
        "anchor": "Hyperhoneycomb boron nitride with anisotropic mechanical, electronic and\n  optical properties: Boron nitride structures have excellent thermal and chemical stabilities.\nBased on state-of-art theoretical calculations, we propose a wide gap\nsemiconducting BN crystal with a three-dimensional hyperhoneycomb structure\n(Hp-BN), which is both mechanically and thermodynamically stable. Our\ncalculated results show that Hp-BN has a higher bulk modulus and a smaller\nenergy gap as compared to c-BN. Moreover, due to the unique bonding structure,\nHp-BN exhibits anisotropic electronic and optical properties. It has great\nadsorption in the ultraviolet region, but it is highly transparent in the\nvisible and infrared region, suggesting that the Hp-BN crystal could have\npotential applications in electronic and optical devices.",
        "positive": "An easily prepared, simple information storage and display device based\n  on triboelectric enhanced mechanoluminescence phenomenon and\n  droplet-luminescence: One easy-make, flexible information storage and display device is prepared.\nThe device show memory effect, which can record the friction trace in real time\nthrough the triboelectric effect, and then reproduce the trajectory under the\nexcitation of any kind of polar liquid droplet, completely display the\ntriboelectric area. The explanation mechanism of this phenomenon is proposed,\nand the main influencing factors of the frictional electrification between\nsolid materials and flexible substrates are determined by systematic\nexperiements. This phenomenon connects mechanoluminescence,\nelectroluminescence, and triboelectrification. It is of great significance to\nthe research of triboelectricity and mechanoluminescence, and is expected to\nplay an important role in display, information storage and encryption."
    },
    {
        "anchor": "Machine learning modeling of high entropy alloy: the role of short-range\n  order: The development of machine learning sheds new light on the traditionally\ncomplicated problem of thermodynamics in multicomponent alloys. Successful\napplication of such a method, however, strongly depends on the quality of the\ndata and model. Here we propose a scheme to improve the representativeness of\nthe data by utilizing the short-range order (SRO) parameters to survey the\nconfiguration space. Using the improved data, a pair interaction model is\ntrained for the NbMoTaW high entropy alloy using linear regression. Benefiting\nfrom the physics incorporated into the model, the learned effective Hamiltonian\ndemonstrates excellent predictability over the whole configuration space. By\nincluding pair interactions within the 6th nearest-neighbor shell, this model\nachieves an $R^2$ testing score of 0.997 and root mean square error of 0.43\nmeV. We further perform a detailed analysis on the effects of training data,\ntesting data, and model parameters. The results reveal the vital importance of\nrepresentative data and physical model. On the other hand, we also examined the\nperformance neural networks, which is found to demonstrate a strong tendency to\noverfit the data.",
        "positive": "Density of mechanisms within the flexibility window of zeolites: By treating idealized zeolite frameworks as periodic mechanical trusses, we\nshow that the number of flexible folding mechanisms in zeolite frameworks is\nstrongly peaked at the minimum density end of their flexibility window. 25 of\nthe 197 known zeolite frameworks exhibit an extensive flexibility, where the\nnumber of unique mechanisms increases linearly with the volume when long\nwavelength mechanisms are included. Extensively flexible frameworks therefore\nhave a maximum in configurational entropy, as large crystals, at their lowest\ndensity. Most real zeolites do not exhibit extensive flexibility, suggesting\nthat surface and edge mechanisms are important, likely during the nucleation\nand growth stage. The prevalence of flexibility in real zeolites suggests that,\nin addition to low framework energy, it is an important criterion when\nsearching large databases of hypothetical zeolites for potentially useful\nrealizable structures."
    },
    {
        "anchor": "Structural Disorder and Elementary Magnetic Properties of Triangular\n  Lattice ErMgGaO4 Single Crystals: The single crystal growth, structure, and basic magnetic properties of\nErMgGaO4 are reported. The structure consists of triangular layers of magnetic\nErO6 octahedra separated by a double layer of randomly occupied non-magnetic\n(Ga,Mg)O5 bipyramids. The Er atoms are positionally disordered. Magnetic\nmeasurements parallel and perpendicular to the c axis of a single crystal\nreveal dominantly antiferromagnetic interactions, with a small degree of\nmagnetic anisotropy. A weighted average of the directional data suggests an\nantiferromagnetic Curie Weiss temperature of approximately -30 K. Below 10 K\nthe temperature dependences of the inverse susceptibilities in the in-plane and\nperpendicular-to plane directions are parallel, indicative of an isotropic\nmagnetic moment at low temperatures. No sign of magnetic ordering is observed\nabove 1.8 K, suggesting that ErMgGaO4 is a geometrically frustrated magnet.",
        "positive": "On the classification and quantification of crystal defects after\n  energetic bombardment by machine learned molecular dynamics simulations: The analysis of the damage on plasma facing materials (PFM), due to its\ndirect interaction with the plasma environment, is needed to build the next\ngeneration of nuclear machines, where tungsten has been proposed as a\ncandidate. In this work, we perform molecular dynamics (MD) simulations using a\nmachine learned inter-atomic potential, based on the Gaussian Approximation\nPotential framework, to model better neutron bombardment mechanisms in pristine\nW lattices. The MD potential is trained to reproduce realistic short-range\ndynamics, the liquid phase, and the material recrystallization, which are\nimportant for collision cascades. The formation of point defects is quantified\nand classified by a descriptor vector (DV) based method, which is independent\nof the sample temperature and its constituents, requiring only modest\ncomputational resources. The locations of vacancies are calculated by the\nk-d-tree algorithm. The analysis of the damage in the W samples is compared to\nresults obtained by EAM Finnis-Sinclair and Tersoff-ZBL potentials, at a sample\ntemperature of 300 K and a primary knock-on atom (PKA) energy range of 0.5-10\nkeV, where a good agreement with the reported number of Frenkel pair is\nobserved. Our results provide information about the advantages and limits of\nthe machine learned MD simulations with respect to the standard ones. The\nformation of dumbbell and crowdion defects as a function of PKA is discussed."
    },
    {
        "anchor": "Circuit-aware Device Modeling of Energy-efficient Monolayer WS$_2$\n  Trench-FinFETs: The continuous scaling of semiconductor technology has pushed the footprint\nof logic devices below 50 nm. Currently, logic standard cells with one single\nfin are being investigated to increase the integration density, although such\noptions could severely limit the performance of individual devices. In this\nletter, we present a novel Trench (T-) FinFET device, composed of a monolayer\ntwo-dimensional (2D) channel material. The device characteristics of a\nmonolayer WS$_2$-based T-FinFET are studied by combining the first-principles\ncalculations and quantum transport (QT) simulations. These results serve as\ninputs to a predictive analytical model. The latter allows to benchmark the\nT-FinFET with strained (s)-Si FinFETs in both quasi-ballistic and diffusive\ntransport regimes. The circuit-level evaluation highlights that WS$_2$\nT-FinFETs exhibit a competitive energy-delay performance compared to s-Si\nFinFET and WS$_2$ double-gate transistors, assuming the same mobility and\ncontact resistivity at small footprints.",
        "positive": "Generalization of Graph-Based Active Learning Relaxation Strategies\n  Across Materials: Although density functional theory (DFT) has aided in accelerating the\ndiscovery of new materials, such calculations are computationally expensive,\nespecially for high-throughput efforts. This has prompted an explosion in\nexploration of machine learning assisted techniques to improve the\ncomputational efficiency of DFT. In this study, we present a comprehensive\ninvestigation of the broader application of Finetuna, an active learning\nframework to accelerate structural relaxation in DFT with prior information\nfrom Open Catalyst Project pretrained graph neural networks. We explore the\nchallenges associated with out-of-domain systems: alcohol ($C_{>2}$) on metal\nsurfaces as larger adsorbates, metal-oxides with spin polarization, and\nthree-dimensional (3D) structures like zeolites and metal-organic-frameworks.\nBy pre-training machine learning models on large datasets and fine-tuning the\nmodel along the simulation, we demonstrate the framework's ability to conduct\nrelaxations with fewer DFT calculations. Depending on the similarity of the\ntest systems to the training systems, a more conservative querying strategy is\napplied. Our best-performing Finetuna strategy reduces the number of DFT\nsingle-point calculations by 80% for alcohols and 3D structures, and 42% for\noxide systems."
    },
    {
        "anchor": "Sound modes in composite incommensurate crystals: We propose a simple phenomenological model describing composite crystals,\nconstructed from two parallel sets of periodic inter-penetrating chains. In the\nharmonic approximation and neglecting thermal fluctuations we find the\neigenmodes of the system. It is shown that at high frequencies there are two\nlongitudinal sound modes with standard attenuation, while in the low frequency\nregion there is one propagating sound mode and an over-damped phase mode. The\ncrossover between these two regions is analyzed numerically and the dynamical\nstructure factor is calculated. It is shown that the qualitative features of\nthe experimentally observed spectra can be consistently described by our model.",
        "positive": "Bright sub-20 nm cathodoluminescent nanoprobes for multicolor electron\n  microscopy: Electron microscopy (EM) has been instrumental in our understanding of\nbiological systems ranging from subcellular structures to complex organisms.\nAlthough EM reveals cellular morphology with nanoscale resolution, it does not\nprovide information on the location of proteins within a cellular context. An\nEM-based bioimaging technology capable of localizing individual proteins and\nresolving protein-protein interactions with respect to cellular ultrastructure\nwould provide important insights into the molecular biology of a cell. Here, we\nreport on the development of luminescent nanoprobes potentially suitable for\nlabeling biomolecules in a multicolor EM modality. In this approach, the labels\nare based on lanthanide-doped nanoparticles that emit light under electron\nexcitation in a process known as cathodoluminescence (CL). Our results suggest\nthat the optimization of nanoparticle composition, synthesis protocols and\nelectron imaging conditions could enable high signal-to-noise localization of\nbiomolecules with a sub-20-nm resolution, limited only by the nanoparticle\nsize. In ensemble measurements, these luminescent labels exhibit narrow spectra\nof nine distinct colors that are characteristic of the corresponding rare-earth\ndopant type."
    },
    {
        "anchor": "Ab-initio study of BaTiO3 surfaces: We have carried out first-principles total-energy calculations of (001)\nsurfaces of the tetragonal and cubic phases of BaTiO3. Both BaO-terminated\n(type I) and TiO2-terminated (type II) surfaces are considered, and the atomic\nconfigurations have been fully relaxed. We found no deep-gap surface states for\nany of the surfaces, in agreement with previous theoretical studies. However,\nthe gap is reduced for the type-II surface, especially in the cubic phase. The\nsurface relaxation energies are found to be substantial, i.e., many times\nlarger than the bulk ferroelectric well depth. Nevertheless, the influence of\nthe surface upon the ferroelectric order parameter is modest; we find only a\nsmall enhancement of the ferroelectricity near the surface.",
        "positive": "Multiferroicity and magnetoelectric coupling in \u03b1-CaCr2O4: Ferroelectricity in the incommensurate helical magnetic phase (below TN, 43K)\nof alpha CaCr2O4 has been confirmed by pyroelectric measurements.\nMagnetoelectric and magnetodielectric coupling exist below TN and are\nproportional to the square of magnetic field. From symmetry analysis, we\nsuggest that the presence of an external electric field destabilizes the\nsymmetrical 2221' phase and stabilizes 21' symmetry. This provides a unique\nsystem in which polarization varies as the fourth-degree of the order-parameter\namplitude and exhibit a vanishingly small value below the first-order\ntransition at TN, as observed experimentally."
    },
    {
        "anchor": "Search For Hole Mediated Ferromagnetism In Cubic (Ga,Mn)N: Results of magnetisation measurements on p-type zincblende-(Ga,Mn)N are\nreported. In addition to a small high temperature ferromagnetic signal, we\ndetect ferromagnetic correlation among the remaining Mn ions, which we assign\nto the onset of hole-mediated ferromagnetism in (Ga,Mn)N.",
        "positive": "Density functional theory study of phase stability, vibrational and\n  electronic properties of $Mo_3Al_2C$: Based on density functional theory the noncentrosymmetric superconductor\nMo_3Al_2C in its well established {\\beta}-Mn type ($P4_{1}32$) crystal\nstructure is investigated. In particular, its thermodynamical and dynamical\nstabilities are studied by calculating lattice vibrations within the harmonic\napproximation. It is found that the fully stoichiometric compound is\ndynamically unstable. However, compounds with carbon vacancies, i.e.,\nMo_3Al_2C_{1-x}, can be dynamically stabilized for vacancy concentrations x >\n0.09. By means of a simple thermodynamical model we estimate x ~ 0.13-0.14 for\nMo_3Al_2C_{1-x} at the experimental preparation temperatures. The influence of\nthe carbon vacancy concentration on the electronic structure is investigated."
    },
    {
        "anchor": "Plasmonic Nanoslit Arrays Fabricated by Serial Bideposition: Optical and\n  Surface-Enhanced Raman Scattering Study: Recently, studies have been carried out on attempts to combine\nsurface-enhanced Surface-enhanced Raman spectroscopy (SERS) substrates that can\nbe based on either localized surface plasmon (LSP) or surface plasmon\npolaritons (SPP) structures. By combining these two systems, the drawbacks of\neach other can be solved. However, the manufacturing methods involved so far\nare sophisticated, labor-intensive, expensive, and also technically demanding.\nWe propose a facile method for the fabrication of a flexible plasmonic nanoslit\nSERS sensor. We utilized the pattern on periodic optical disks (DVD-R) as a\ncheap substitute for printing the periodic pattern on PDMS with soft imprint\nlithography. Ag nanoslit (AgNS) was fabricated by serial bideposition using a\ndynamic oblique angle deposition (DOD) technique. The nanoslit structures were\nphysically and optically characterized, and the experimental results were\ncompared to the numerical simulation studies; Monte Carlo and the\nfinite-difference time-domain (FDTD) simulation. The Ag nanoslit structure\nshowed an excellent SERS enhancement, and its biosensing capability was\ndemonstrated by the sensing of bilirubin.",
        "positive": "A First-principles Prediction of Two-Dimensional Superconductivity in\n  Pristine B2C Single layer: Based on first-principles lattice dynamics and electron-phonon coupling\ncalculations, B2C sheet is predicted to be a two-dimensional (2D)\nphonon-mediated superconductor with a relatively high transition temperature\n(Tc). The electron-phonon coupling parameter calculated is 0.92, and it is\nmainly contributed by low frequency out-of-plane phonon modes and electronic\nstates with a {\\pi} character. When the Coulomb pseudopotential is set to 0.10,\nthe estimated temperature Tc is 19.2 K. To be best of our knowledge, B2C is the\nfirst pristine 2D superconductor with a Tc higher than the boiling point of\nliquid helium."
    },
    {
        "anchor": "Gapless Dirac surface states in the antiferromagnetic topological\n  insulator MnBi2Te4: We use high-resolution, tunable angle-resolved photoemission spectroscopy\n(ARPES) and density functional theory (DFT) calculations to study the\nelectronic properties of single crystals of MnBi2Te4, a material that was\npredicted to be the first intrinsic antiferromagnetic (AFM) topological\ninsulator. We observe both bulk and surface bands in the electronic spectra, in\nreasonable agreement with the DFT calculations results. In striking contrast to\nthe earlier literatures showing a full gap opening between two surface band\nmanifolds along (0001) direction, we observed a gapless Dirac cone remain\nprotected in MnBi2Te4 across the AFM transition (TN = 24 K). Our data also\nreveal the existence of a second Dirac cone closer to the Fermi level,\npredicted by band structure calculations. Whereas the surface Dirac cones seem\nto be remarkably insensitive to the AFM ordering, we do observe splitting of\nthe bulk band that develops below the TN . Having a moderately high ordering\ntemperature, MnBi2Te4 provides a unique platform for studying the interplay\nbetween topology and magnetic ordering.",
        "positive": "Accurate screened exchange band structures for transition metal\n  monoxides MnO, FeO, CoO and NiO: We report calculations of the band structures and density of states of the\nfour transition metal monoxides MnO, FeO, CoO and NiO using the hybrid density\nfunctional sX-LDA. Late transition metal oxides are prototypical examples of\nstrongly correlated materials, which pose challenges for electronic structure\nmethods. We compare our results with available experimental data and show that\nour calculations yield accurate predictions for the fundamental band gaps and\nvalence bands of FeO, CoO and NiO. For MnO, the band gaps are underestimated,\nsuggesting additional many-body effects that are not captured by our screened\nhybrid functional approach."
    },
    {
        "anchor": "Investigations of thermometric characteristics of p+-n - type GaP diodes: The technique of obtaining of p+-n-type gallium phosphide diode epitaxial\nstructures from liquid phase was developed as well as pilot samples of diode\ntemperature sensors were fabricated based on them. Thermometric and\ncurrent-voltage characteristics of the test diodes were measured in the\ntemperature range of 80 / 520K and their basic technical characteristics were\ndetermined. An availability of application of the structures developed as\nsensing elements of high-temperature heat sensors was shown.",
        "positive": "Structural phase transition and material properties of few-layer\n  monochalcogenides: GeSe and SnSe monochalcogenide monolayers and bilayers undergo a\ntwo-dimensional phase transition from a rectangular unit cell to a square unit\ncell at a temperature $T_c$ well below the melting point. Its consequences on\nmaterial properties are studied within the framework of Car-Parrinello\nmolecular dynamics and density-functional theory. No in-gap states develop as\nthe structural transition takes place, so that these phase-change materials\nremain semiconducting below and above $T_c$. As the in-plane lattice transforms\nfrom a rectangle onto a square at $T_c$, the electronic, spin, optical, and\npiezo-electric properties dramatically depart from earlier predictions. Indeed,\nthe $Y-$ and $X-$points in the Brillouin zone become effectively equivalent at\n$T_c$, leading to a symmetric electronic structure. The spin polarization at\nthe conduction valley edge vanishes, and the hole conductivity must display an\nanomalous thermal increase at $T_c$. The linear optical absorption band edge\nmust change its polarization as well, making this structural and electronic\nevolution verifiable by optical means. Much excitement has been drawn by\ntheoretical predictions of giant piezo-electricity and ferroelectricity in\nthese materials, and we estimate a pyroelectric response of about $3\\times\n10^{-12}$ $C/K m$ here. These results uncover the fundamental role of\ntemperature as a control knob for the physical properties of few-layer group-IV\nmonochalcogenides"
    },
    {
        "anchor": "Influence of stress-free transformation strain on the autocatalytic\n  growth of bainite: A multiphase-field analysis: Analytical treatments, formulated to predict the rate of the bainite\ntransformation, define autocatalysis as the growth of the subunits at the\nbainite-austenite interface. Furthermore, the role of the stress-free\ntransformation strain is often translated to a thermodynamic criterion that\nneeds to be fulfilled for the growth of the subunits. In the present work, an\nelastic phase-field model, which elegantly recovers the sharp-interface\nrelations, is employed to comprehensively explicate the effect of the elastic\nenergy on the evolution of the subunits. The primary finding of the current\nanalysis is that the role of eigenstrains in the bainite transformation is\napparently complicated to be directly quantified as the thermodynamic\nconstraint. It is realized that the inhomogeneous stress state, induced by the\ngrowth of the primary subunit, renders a spatially dependent ill- and\nwell-favored condition for the growth of the secondary subunits. A favorability\ncontour, which encloses the sections that facilitate the elastically preferred\ngrowth, is postulated based on the elastic interaction. Through the numerical\nanalyses, the enhanced growth of the subunits within the favorability-contour\nis verified. Current investigations show that the morphology and size of the\nelastically preferred region respectively changes and increases with the\nprogressive growth of the subunits.",
        "positive": "Enhancing the understanding of hydrogen evolution and oxidation reaction\n  on Pt(111) through ab initio simulations on electrode/electrolyte kinetics: The hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER)\nplay an important role in hydrogen based energy conversion. Recently, the\nfrustrating performance in alkaline media raised debates on the relevant\nmechanism, especially on the role of surface hydroxyl (OH*). We present a full\npH range electrode/electrolyte kinetics simulation for HER/HOR on Pt(111), with\nthe potential-related rate constants been calculated with density functional\ntheory methods. The polarization curves agree well with the experimental\nobservations. The stability of OH* is found to be unlikely an effective\nactivity descriptor since it is irrelevant to the onset potential of HOR/HER.\nDegree of rate control analyses reveal that the alkaline current is controlled\njointly by Tafel and Volmer steps, while the acidic current solely by Tafel\nstep, which explains the observed pH-dependent kinetics. Therefore, it is also\npossible to reduce the overpotential of alkaline HER/HOR by accelerating the\nTafel step besides tuning the hydrogen binding energy."
    },
    {
        "anchor": "3d Transition Metals and Oxides within Carbon Nanotubes by Co-Pyrolysis\n  of Metallocene & Camphor: High Filling Efficiency and Self-Organized\n  Structures: We demonstrate that a single zone furnace with a modified synthesis chamber\ndesign is sufficient to obtain metal (Fe, Co or Ni) filled carbon nanotubes\n(CNT) with high filling efficiency and controlled morphology. Samples are\nformed by pyrolysis of metallocenes, a synthesis technique that otherwise\nrequires a dual zone furnace. Respective metallocene in all three cases are\nsublimed in powder form, a crucial factor for obtaining high filling\nefficiency. While Fe@CNT is routinely produced using this technique,\nwell-formed Ni@CNT or Co@CNT samples are reported for the first time. This is\nachieved by sublimation of nickelocene (or cobaltocene) in combination with\n'camphor'. These samples exhibit some of the highest saturation magnetization\n(Ms) values, at least an order of magnitude higher than that reported for Ni or\nCo filled CNT, by aerosol assisted pyrolysis. The results also elucidate on why\nNi or Co@CNT are relatively difficult to obtain by pyrolyzing powder\nmetallocene alone. Overall, a systematic variation of synthesis parameters\nprovides insights for obtaining narrow length and diameter distribution and\nreduced residue particles outside filled CNT - factors which are important for\ndevice related applications. Finally, the utility of this technique is\ndemonstrated by obtaining highly aligned forest of Fe2O3@CNT, wherein Fe2O3 is\na functional magnetic oxide relevant to spintronics and battery applications.",
        "positive": "Inverse Spin Hall Effect from pulsed Spin Current in Organic\n  Semiconductors with Tunable Spin-Orbit Coupling: Exploration of spin-currents in organic semiconductors (OSECs) induced by\nresonant microwave absorption in ferromagnetic substrates has been of great\ninterest for potential spintronics applications. Due to the inherently weak\nspin-orbit coupling (SOC) of OSECs, their inverse spin Hall effect (ISHE)\nresponse is very subtle; limited by the microwave power applicable under\ncontinuous-wave (cw) excitation. Here we introduce a novel approach for\ngenerating significant ISHE signals using pulsed ferromagnetic resonance, where\nthe ISHE is ~2-3 orders of magnitude larger compared to cw excitation. This\nstrong ISHE enables us to investigate a variety of OSECs ranging from\npi-conjugated polymers with strong SOC that contain intrachain platinum atoms,\nto weak SOC polymers, to C60 films, where the SOC is predominantly caused by\nthe molecule surface curvature. The pulsed-ISHE technique offers a robust route\nfor efficient injection and detection schemes of spin-currents at room\ntemperature, and paves the way for spin-orbitronics in plastic materials."
    },
    {
        "anchor": "A rule-free workflow for the automated generation of databases from\n  scientific literature: In recent times, transformer networks have achieved state-of-the-art\nperformance in a wide range of natural language processing tasks. Here we\npresent a workflow based on the fine-tuning of BERT models for different\ndownstream tasks, which results in the automated extraction of structured\ninformation from unstructured natural language in scientific literature.\nContrary to existing methods for the automated extraction of structured\ncompound-property relations from similar sources, our workflow does not rely on\nthe definition of intricate grammar rules. Hence, it can be adapted to a new\ntask without requiring extensive implementation efforts and knowledge. We test\nour data-extraction workflow by automatically generating a database for Curie\ntemperatures and one for band gaps. These are then compared with\nmanually-curated datasets and with those obtained with a state-of-the-art\nrule-based method. Furthermore, in order to showcase the practical utility of\nthe automatically extracted data in a material-design workflow, we employ them\nto construct machine-learning models to predict Curie temperatures and band\ngaps. In general we find that, although more noisy, automatically extracted\ndatasets can grow fast in volume and that such volume partially compensates for\nthe inaccuracy in downstream tasks.",
        "positive": "Excitons in atomically thin transition metal dichalcogenides: Atomically thin materials such as graphene and monolayer transition metal\ndichalcogenides (TMDs) exhibit remarkable physical properties resulting from\ntheir reduced dimensionality and crystal symmetry. The family of semiconducting\ntransition metal dichalcogenides is an especially promising platform for\nfundamental studies of two-dimensional (2D) systems, with potential\napplications in optoelectronics and valleytronics due to their direct band gap\nin the monolayer limit and highly efficient light-matter coupling. A crystal\nlattice with broken inversion symmetry combined with strong spin-orbit\ninteractions leads to a unique combination of the spin and valley degrees of\nfreedom. In addition, the 2D character of the monolayers and weak dielectric\nscreening from the environment yield a significant enhancement of the Coulomb\ninteraction. The resulting formation of bound electron-hole pairs, or excitons,\ndominates the optical and spin properties of the material. Here we review\nrecent progress in our understanding of the excitonic properties in monolayer\nTMDs and lay out future challenges. We focus on the consequences of the strong\ndirect and exchange Coulomb interaction, discuss exciton-light interaction and\neffects of other carriers and excitons on electron-hole pairs in TMDs. Finally,\nthe impact on valley polarization is described and the tuning of the energies\nand polarization observed in applied electric and magnetic fields is\nsummarized."
    },
    {
        "anchor": "Phonon thermal transport in UO$_2$ via self-consistent perturbation\n  theory: Computing thermal transport from first-principles in UO$_2$ is complicated\ndue to the challenges associated with Mott physics. Here we use irreducible\nderivative approaches to compute the cubic and quartic phonon interactions in\nUO$_2$ from first-principles, and we perform enhanced thermal transport\ncomputations by evaluating the phonon Green's function via self-consistent\ndiagrammatic perturbation theory. Our predicted phonon lifetimes at $T=600$ K\nagree well with our inelastic neutron scattering measurements across the entire\nBrillouin zone, and our thermal conductivity predictions agree well with\nprevious measurements. Both the changes due to thermal expansion and\nself-consistent contributions are nontrivial at high temperatures, though the\neffects tend to cancel, and interband transitions yield a substantial\ncontribution.",
        "positive": "Object Storage, Persistent Memory, and Data Infrastructure for HPC\n  Materials Informatics: Speculation is provided on how infrastructure choices fit into the materials\ndata ecosystem. Special attention is paid to object storage, the Intel DAOS\nAPI, storage-class memory (SCM), and the prospect of non-von Neumann computing.\nLastly, the hypothesized implications of data infrastructure choices on a\nsample materials informatics problem is discussed: computational materials\ndiscovery of phase-change materials with properties tailored for phase-change\nmemory (PCM). The motivation for selecting PCM as a sample materials\ninformatics case study comes from its relevance to emerging SCM hardware."
    },
    {
        "anchor": "Self-organized plane arrays of metallic magnetic elements: We studied the dynamic magnetic properties of plane periodical arrays of\ncircular permalloy nano-dots fabricated using a self-organized mask formed by\npolysterene nanospheres on the surface of a Permalloy film. Conventional\n(microwave cavity) and broadband coplanar-line ferromagnetic resonance setups\nwere used for the measurements. We found several well resolved resonance peaks.\nThis result shows that the self-organized mask fabrication technique is able to\nproduce high-quality samples with small dispersion of geometrical and magnetic\nparameters.",
        "positive": "Development and application of a particle-particle particle-mesh Ewald\n  method for dispersion interactions: For inhomogeneous systems with interfaces, the inclusion of long-range\ndispersion interactions is necessary to achieve consistency between molecular\nsimulation calculations and experimental results. For accurate and efficient\nincorporation of these contributions, we have implemented a particle-particle\nparticle-mesh (PPPM) Ewald solver for dispersion ($r^{-6}$) interactions into\nthe LAMMPS molecular dynamics package. We demonstrate that the solver's\n$\\mathcal{O}(N\\log N)$ scaling behavior allows its application to large-scale\nsimulations. We carefully determine a set of parameters for the solver that\nprovides accurate results and efficient computation. We perform a series of\nsimulations with Lennard-Jones particles, SPC/E water, and hexane to show that\nwith our choice of parameters the dependence of physical results on the chosen\ncutoff radius is removed. Physical results and computation time of these\nsimulations are compared to results obtained using either a plain cutoff or a\ntraditional Ewald sum for dispersion."
    },
    {
        "anchor": "High pressure structural, electronic, and optical properties of\n  polymorphic InVO4 phases: In the present work, we report a detailed density functional theory\ncalculation on polymorphic InVO$_4$ phases by means of projector augmented wave\nmethod. The computed first-order structural phase transformation from\northorhombic \\emph{(Cmcm)} to monoclinic \\emph{(P2/c)} structure is found to\noccur around 5.6 GPa along with a large volume collapse of 16.6$\\%$, which is\nconsistent with previously reported experimental data. This transformation also\nleads to an increase in the coordination number of vanadium atom from 4 to 6.\nThe computed equilibrium and high pressure structural properties of both\nInVO$_4$ phases, including unit cell parameters, equation of state, and bulk\nmoduli, are in good agreement with the available experimental data. In\naddition, compressibility is found to be highly anisotropic and the\n\\emph{b}-axis being more compressible than the other for both the structures.\nElectronic band structures for both the phases were calculated, and the band\ngap for orthorhombic and monoclinic InVO$_4$ are found to be 4.02 and 1.67 eV,\nrespectively, within the Tran-Blaha Modified Becke-Johnson potential as\nimplemented in linearized augmented planewave method. We further examined the\noptical properties such as dielectric function, refractive index, and\nabsorption spectra for both the structures. From the implications of these\nresults, it can be proposed that the high pressure InVO$_4$ phase can be more\nuseful than orthorhombic phase for photo catalytic applications.",
        "positive": "Development of a fracture capture simulator to quantify the instability\n  evolution in porous medium: Understanding and controlling fracture propagation is one of the most\nchallenging engineering problems, especially in the oil and gas sector,\ngroundwater hydrology and geothermal energy applications. Predicting the\nfracture orientation while also possessing a non-linear material response\nbecomes more complex when the medium is non-homogeneous and anisotropic.\nFracturing behaviour in geological porous media that exhibit high leak-off\npotential is not clearly understood. In this context, a novel testing technique\nis used to simulate the ground conditions in the laboratory and study the\ninstability characteristics of such geo-materials. The bespoke apparatus\ndesigned and developed in this research programme is capable of applying true\nanisotropic boundary stresses, injecting fluid at a predefined flow rate and\nviscosity while also imaging the instability/ fracture propagation in a porous\nmedium such as sand and weak rock. Pressure profiles and the progression of\nfracture are recorded simultaneously during the fluid injection process into\nspecimens subjected to different boundary stresses. The fracture propagation\ndata are analysed, which provides information on the evolution of fracture\nmorphology and expansion velocity during the injection event."
    },
    {
        "anchor": "Selective capture of CO2 over N2 and CH4: B clusters and their size\n  effects: Using density-functional theory (DFT), we investigate the selectivity of\nadsorption of CO2 over N2 and CH4 on planar-type B clusters, based on our\nprevious finding of strong chemisorption of CO2 on the B10-13 planar and\nquasiplanar clusters. We consider the prototype B8 and B12 planar-type clusters\nand perform a comparative study of the adsorption of the three molecules on\nthese clusters. We find that, at room temperature, CO2 can be separated from N2\nby selective binding to the B12 cluster and not to the B8 cluster. Selective\nadsorption of CO2 over CH4 at room temperature is possible for both clusters.\nBased on our DFT-adsorption data (including also a semi-infinite Boron sheet)\nand the available literature-adsorption value for N2 on the planar-type B36\ncluster, we discuss the selectivity trend of CO2 adsorption over N2 and CH4\nwith planar-cluster size, showing that it extends over sizes including B10-13\nclusters and significantly larger.",
        "positive": "Spin diffusion at finite electric and magnetic fields: Spin transport properties at finite electric and magnetic fields are studied\nby using the generalized semiclassical Boltzmann equation. It is found that the\nspin diffusion equation for non-equilibrium spin density and spin currents\ninvolves a number of length scales that explicitly depend on the electric and\nmagnetic fields. The set of macroscopic equations can be used to address a\nbroad range of the spin transport problems in magnetic multilayers as well as\nin semiconductor heterostructure. A specific example of spin injection into\nsemiconductors at arbitrary electric and magnetic fields is illustrated."
    },
    {
        "anchor": "Structural Properties of Two-Dimensional Strontium Titanate: A\n  First-Principles Investigation: Motivated by the experimental synthesis of two-dimensional (2D) perovskite\nmaterials, we study the stability of 2D SrTiO$_3$ from first principles. We\nfind that the TiO$_6$ octahedral rotations emerge in 2D SrTiO$_3$ with a\nrotation angle twice that in the 3D bulk. The rotation angle decreases\nsignificantly with the film thickness, reflecting the strong interlayer\ncoupling that is absent in the conventional 2D materials. Using the molecular\ndynamics simulations, the cubic-like phase is found to appear above 1000 K that\nis much higher than the transition temperature of 3D SrTiO$_3$.",
        "positive": "Effect of n+-GaAs thickness and doping density on spin injection of\n  GaMnAs/n+-GaAs Esaki tunnel junction: We investigated the influence of n+-GaAs thickness and doping density of\nGaMnAs/n+-GaAs Esaki tunnel junction on the efficiency of the electrical\nelectron spin injection. We prepared seven samples of GaMnAs/n+-GaAs tunnel\njunctions with different n+-GaAs thickness and doping density grown on\nidentical p-AlGaAs/p-GaAs/n-AlGaAs light emitting diode (LED) structures.\nElectroluminescence (EL) polarization of the surface emission was measured\nunder the Faraday configuration with external magnetic field. All samples have\nthe bias dependence of the EL polarization, and higher EL polarization is\nobtained in samples in which n+-GaAs is completely depleted at zero bias. The\nEL polarization is found to be sensitive to the bias condition for both the\n(Ga,Mn)As/n+-GaAs tunnel junction and the LED structure."
    },
    {
        "anchor": "The magnetic field generated by a charge in a uniaxial magnetoelectric\n  material: We revisit the description of the magnetic field around antiferromagnetic\nmagnetoelectrics in the context of recent developments regarding\nmagnetoelectric monopoles. Using Maxwell's equations, we calculate the magnetic\nand electric fields associated with a free charge in a bulk uniaxial\nmagnetoelectric, as well as in a finite sphere of magnetoelectric material. We\nshow that a charge in the prototypical magnetoelectric Cr$_2$O$_3$, which is\nuniaxial with a diagonal magnetoelectric response, induces an internal magnetic\nfield with both monopolar and quadrupolar components, but that only the\nquadrupolar contribution extends beyond the sample surface. We discuss the\nbehavior of the external quadrupolar field and compare its magnitude to those\nof magnetic fields from other sources.",
        "positive": "Impact of Casimir Force in Molecular Electronic Switching Junctions: Despite significant progress in synthesizing several new molecules and many\npromising single device demonstrations, wide range acceptance of molecular\nelectronics as an alternative to CMOS technology has been stalled not only by\ncontroversial theories of a molecular device`s operation, for example the\nswitching mechanism, but also by our inability to reproducibly fabricate large\narrays of devices. In this paper, we investigate the role of Casimir force as\none of the potential source of a wide range of discrepancies in the reported\nelectrical characteristics and high rate of device shorting in molecular\nelectronic switching junctions fabricated by sandwiching a molecular monolayer\nbetween a pair of planar metal electrode."
    },
    {
        "anchor": "Twisted phase of the orbital-dominant ferromagnet SmN in a GdN/SmN\n  heterostructure: The strong spin-orbit interaction in the rare-earth elements ensures that\neven within a ferromagnetic state there is a substantial orbital contribution\nto the ferromagnetic moment, in contrast to more familiar transition metal\nsystems, where the orbital moment is usually quenched. The orbital-dominant\nmagnetization that is then possible within rare-earth systems facilitates the\nfabrication of entirely new magnetic heterostructures, and here we report a\nstudy of a particularly striking example comprising interfaces between GdN and\nSmN. Our investigation reveals a twisted magnetization arising from the large\nspin-only magnetic moment in GdN and the nearly zero, but orbital-dominant,\nmoment of SmN. The unusual twisted phase is driven by (i) the similar ferromag-\nnetic Gd-Gd, Sm-Sm and Gd-Sm exchange interactions, (ii) a SmN Zeeman\ninteraction 200 times weaker than that of GdN, and (iii) the orbital-dominant\nSmN magnetic moment. The element specificity of X-ray magnetic circular\ndichroism (XMCD) is used in seperate modes probing both bulk and surface\nregions, revealing the depth profile of the twisting magnetization.",
        "positive": "Design of Chern Insulating Phases in Honeycomb Lattices: The search for robust examples of the magnetic version of topological\ninsulators, referred to as quantum anomalous Hall insulators or simply Chern\ninsulators, so far lacks success. Our groups have explored two distinct\npossibilities based on multiorbital 3d oxide honeycomb lattices. Each has a\nChern insulating phase near the ground state, but materials parameters were not\nappropriate to produce a viable Chern insulator. Further exploration of one of\nthese classes, by substituting open shell 3d with 4d and 5d counterparts, has\nled to realistic prediction of Chern insulating ground states. Here we recount\nthe design process, discussing the many energy scales that are active in\nparticipating (or resisting) the desired Chern insulator phase."
    },
    {
        "anchor": "First-principles prediction of potentials and space-charge layers in\n  all-solid-state batteries: As all-solid-state batteries (SSBs) develop as an alternative to traditional\ncells, a thorough theoretical understanding of driving forces behind battery\noperation is needed. We present a fully first-principles-informed model of\npotential profiles in SSBs and apply the model to the\nLi/LiPON/$\\text{Li}_x\\text{CoO}_2$ system. The model predicts interfacial\npotential drops driven by both electron transfer and Li$^+$ space-charge layers\nthat vary with the SSB's state of charge. The results suggest lower electronic\nionization potential in the solid electrolyte favors Li$^+$ transport, leading\nto higher discharge power.",
        "positive": "Local Electrical Stress-Induced Doping and Formation of 2D Monolayer\n  Graphene P-N Junction: We demonstrated doping in 2D monolayer graphene via local electrical\nstressing. The doping, confirmed by the resistance-voltage transfer\ncharacteristics of the graphene system, is observed to continuously tunable\nfrom N-type to P-type as the electrical stressing level (voltage) increases.\nTwo major physical mechanisms are proposed to interpret the observed phenomena:\nmodifications of surface chemistry for N-type doping (at low-level stressing)\nand thermally-activated charge transfer from graphene to SiO2 substrate for\nP-type doping (at high-level stressing). The formation of P-N junction on 2D\ngraphene monolayer is demonstrated with complementary doping based on locally\napplied electrical stressing."
    },
    {
        "anchor": "Systematic {\\it ab initio} study of the magnetic and electronic\n  properties of all 3d transition metal linear and zigzag nanowires: It is found that all the zigzag chains except the nonmagnetic (NM) Ni and\nantiferromagnetic (AF) Fe chains which form a twisted two-legger ladder, look\nlike a corner-sharing triangle ribbon, and have a lower total energy than the\ncorresponding linear chains. All the 3d transition metals in both linear and\nzigzag structures have a stable or metastable ferromagnetic (FM) state. The\nelectronic spin-polarization at the Fermi level in the FM Sc, V, Mn, Fe, Co and\nNi linear chains is close to 90% or above. In the zigzag structure, the AF\nstate is more stable than the FM state only in the Cr chain. It is found that\nthe shape anisotropy energy may be comparable to the electronic one and always\nprefers the axial magnetization in both the linear and zigzag structures. In\nthe zigzag chains, there is also a pronounced shape anisotropy in the plane\nperpendicular to the chain axis. Remarkably, the axial magnetic anisotropy in\nthe FM Ni linear chain is gigantic, being ~12 meV/atom. Interestingly, there is\na spin-reorientation transition in the FM Fe and Co linear chains when the\nchains are compressed or elongated. Large orbital magnetic moment is found in\nthe FM Fe, Co and Ni linear chains.",
        "positive": "Role of interfacial oxidation in generation of spin-orbit torques: We report that current-induced spin-orbit torques (SOTs) in\nheavy-metal/ferromagnetic-metal bilayers are strongly altered by the oxidation\nof the ferromagnetic layer near the interface. We measured damping-like (DL)\nand field-like (FL) SOTs for Pt/Co and Pt/Ni$_{81}$Fe$_{19}$ (Pt/Py) films\nusing spin-torque ferromagnetic resonance. In the Pt/Co film, we found that the\noxidation of the Co layer near the interface enhances both DL and FL SOTs in\nspite of the insulating nature of the CoO$_x$ layer. The enhancement of the\nSOTs disappears by inserting a thin Ti layer at the Pt/CoO$_x$ interface,\nindicating that the dominant source of the SOTs in the Pt/CoO$_x$/Co film is\nthe spin-orbit coupling at the Pt/CoO$_x$ interface. In contrast to the\nPt/CoO$_x$/Co film, the SOTs in the Pt/PyO$_x$/Py film are dominated by the\nbulk spin-orbit coupling. Our result shows that the interfacial oxidation of\nthe Pt/Py film suppresses the DL-SOT and reverses the sign of the FL-SOT. The\nchange of the SOTs can be attributed to the change of the real and imaginary\nparts of the spin mixing conductance induced by the insertion of the insulating\nPyO$_x$ layer. These results show that the interfacial oxidation provides an\neffective way to manipulate the strength and sign of the SOTs."
    },
    {
        "anchor": "A first-principles investigation on the effects of magnetism on the Bain\n  transformation of $\u03b1$-phase FeNi systems: The effects of magnetism on the Bain transformation of $\\alpha$-phase FeNi\nsystems are investigated by using the full potential linearized augmented plane\nwave (FLAPW) method based on the generalized gradient approximation (GGA). We\nfound that Ni impurity in bcc Fe increases the lattice constant in\nferromagnetic (FM) states, but not in the nonmagnetic (NM) states. The shear\nmodulus $G$ and Young's modulus $E$ of bcc Fe are also increased by raising the\nconcentration of nickel. All the compositions considered show high shear\nanisotropy and the ratio of the bulk to shear modulus is greater than 1.75\nimplying ductility. The mean sound velocities in the $[100]$ directions are\ngreater than in the $[110]$ directions. The Bain transformation, which is a\ncomponent of martensitic transformation, has also been studied to reveal that\nNi$_{x}$Fe$_{1-x}$ alloys are elastically unstable in the NM states, but not so\nin the FM states. The electronic structures explain these results in terms of\nthe density of states at the Fermi level. It is evident that magnetism cannot\nbe neglected when dealing with the Bain transformation in iron and its alloys.",
        "positive": "Charge Trap Memory Based on Few-Layered Black Phosphorus: Atomically thin layered two-dimensional materials, including transition-metal\ndichacolgenide (TMDC) and black phosphorus (BP), (1) have been receiving much\nattention, because of their promising physical properties and potential\napplications in flexible and transparent electronic devices . Here, for the\nfirst time we show non-volatile chargetrap memory devices, based on\nfield-effect transistors with large hysteresis, consisting of a few-layer black\nphosphorus channel and a three dimensional (3D) Al2O3 /HfO2 /Al2O3 charge-trap\ngate stack. An unprecedented memory window exceeding 12 V is observed, due to\nthe extraordinary trapping ability of HfO2. The device shows a high endurance\nand a stable retention of ?25% charge loss after 10 years, even drastically\nlower than reported MoS2 flash memory. The high program/erase current ratio,\nlarge memory window, stable retention and high on/off current ratio, provide a\npromising route towards the flexible and transparent memory devices utilising\natomically thin two-dimensional materials. The combination of 2D materials with\ntraditional high-k charge-trap gate stacks opens up an exciting field of\nnonvolatile memory devices."
    },
    {
        "anchor": "Control of site occupancy by variation of the Zn and Al content in\n  NiZnAl ferrite epitaxial films with low magnetic damping: The structural and magnetic properties of Zn/Al doped nickel ferrite thin\nfilms can be adjusted by changing the Zn and Al content. The films are\nepitaxially grown by reactive magnetron sputtering using a triple cluster\nsystem to sputter simultaneously from three different targets. Upon the\nvariation of the Zn content the films remain fully strained with similar\nstructural properties, while the magnetic properties are strongly affected. The\nsaturation magnetization and coercivity as well as resonance position and\nlinewidth from ferromagnetic resonance (FMR) measurements are altered depending\non the Zn content in the material. The reason for these changes can be\nelucidated by investigation of the x-ray magnetic circular dichroism spectra to\ngain site and valence specific information with elemental specificity.\nAdditionally, from a detailed investigation by broadband FMR a minimum in\ng-factor and linewidth could be found as a function of film thickness.\nFurthermore, the results from a variation of the Al content using the same set\nof measurement techniques is given. Other than for Zn, the variation of Al\naffects the strain and even more pronounced changes to the magnetic properties\nare apparent.",
        "positive": "Exploring the possible origin of spin reorientation transition in\n  NdCrO$_3$: Spin reorientation transitions and other related magnetic phenomena, which\nowe their origin to the complex interplay between multiple magnetic\nsublattices, have long attracted scientific attention both from the perspective\nof fundamental curiosity and technological applications. In this study,\ncombining first principles calculations together with finite temperature Monte\nCarlo simulations, we explore the possible origins of reorientation transition\nof Cr spins in NdCrO$_3$. We construct a NdCrO$_3$ specific magnetic model,\nconsisting of symmetric superexchange interactions between magnetic ions, as\nwell as their magnetic anisotropy. We show that the observed spin reorientation\nin NdCrO$_3$, arises out of a delicate balance between Nd$-$Cr magnetic\nexchange interactions, single ion anisotropy of Nd spins, and single ion\nanisotropy of Cr spins. Moreover, though our model does not take into\nconsideration the effect of anti-symmetric and anisotropic-symmetric magnetic\nexchanges, the qualitative as well as quantitative agreement of the\ntheoretically derived and the experimentally observed spin-reorientation\ntransition in NdCrO$_3$, confirms the merit of our proposed microscopic model.\nOur results also propose a hitherto unobserved collective magnetic ordering in\nNd sublattice, which is challenging to detect as it is an extreme low\ntemperature phenomena, therefore calls for further investigations."
    },
    {
        "anchor": "Black Phosphorus n-type doping by Cu: a microscopic surface\n  investigation: We study surface charge transfer doping of exfoliated black phosphorus (bP)\nflakes by copper using scanning tunneling microscopy (STM) and spectroscopy\n(STS) at room temperature. The tunneling spectra reveal a gap in correspondence\nof Cu islands, which is attributed to Coulomb blockade phenomena. Moreover,\nusing line spectroscopic measurements across small copper islands, we exploit\nthe potential of the local investigation, showing that the n-type doping effect\nof copper on bP is short-ranged. These experimental results are substantiated\nby first-principles simulations, which quantify the role of cluster size for an\neffective n-type doping of bP and explain the Coulomb blockade by an electronic\ndecoupling of the topmost bP layer from the underlying layers driven by the\ncopper cluster. Our results provide novel understanding, difficult to retrieve\nby transport measurements, of the doping of bP by copper, which appears\npromising for the implementation of ultra-sharp p-n junctions in bP.",
        "positive": "Comparative study of microwave absorption in Ni/SiO2 and SiO2/Ni\n  core-shell structures: Ni coated SiO2 and SiO2 coated Ni composite particles with core-shell\nstructures were designed, prepared and their microwave absorption properties\nwere characterized. The comparison study of the shell effect on the effective\nelectromagnetic parameters reveals that the effective permittivity/permeability\nwas crucially determined by the percent and the intrinsic electromagnetic\nparameters of the component materials regardless of various core/shell\nstructures. Both of the composite core-shell structures could have good\nmicrowave absorption properties. Investigation of the input impedance indicates\nthat, good microwave absorption performances are a consequence of proper\nelectromagnetic impedance matches when the effective electromagnetic parameters\nwere modulated."
    },
    {
        "anchor": "Spin signature of nonlocal-correlation binding in metal organic\n  frameworks: We develop a proper nonempirical spin-density formalism for the van der Waals\ndensity functional (vdW-DF) method. We show that this generalization, termed\nsvdW-DF, is firmly rooted in the single-particle nature of exchange and we test\nit on a range of spin systems. We investigate in detail the role of spin in the\nnonlocal-correlation driven adsorption of H$_2$ and CO$_2$ in the linear\nmagnets Mn-MOF74, Fe-MOF74, Co-MOF74, and Ni-MOF74. In all cases, we find that\nspin plays a significant role during the adsorption process despite the general\nweakness of the molecular-magnetic responses. The case of CO$_2$ adsorption in\nNi-MOF74 is particularly interesting, as the inclusion of spin effects results\nin an increased attraction, opposite to what the diamagnetic nature of CO$_2$\nwould suggest. We explain this counter-intuitive result, tracking the behavior\nto a coincidental hybridization of the O $p$ states with the Ni $d$ states in\nthe down-spin channel. More generally, by providing insight on nonlocal\ncorrelation in concert with spin effects, our nonempirical svdW-DF method opens\nthe door for a deeper understanding of weak nonlocal magnetic interactions.",
        "positive": "An atomic perspective on the serpentine-chlorite solid-state\n  transformation: Serpentine minerals are important components of metamorphic rocks and\npromising geo-materials for nanotechnology. Lizardite, the most abundant\nserpentine mineral, can be transformed into chlorite during metamorphism. This\nintriguing phase transformation should affect the deformation behavior during\naseismic creep and slow slip at the base of the subduction zone, but has not\nbeen understood structurally and chemically at the atomic scale. Here we\nvisualized cations and oxygen atoms using the state-of-the-art low-dose\nscanning transmission electron microscopy and found that restructuring mainly\ninvolves the synergistic migration of tetrahedral cations and oxygen anions,\ncoupled with the migration of octahedral trivalent cations into the\nbrucite-like interlayer. Further, we show that different serpentine polytypes\nresult in distinct regular interstratifications of serpentine and chlorite. Our\nresults clarify the long-standing puzzle of how solid-state layer silicate\ntransformations occur and lead to long-period ordered structures."
    },
    {
        "anchor": "Finding Natural, Dense, and Stable Frustrated Lewis Pairs on Wurtzite\n  Crystal Surfaces: The surface frustrated Lewis pairs (SFLPs) open up new opportunities for\nsubstituting noble metals in the activation and conversion of stable molecules.\nHowever, the applications of SFLPs on a larger scale are impeded by the complex\nconstruction process, low surface density, and sensitivity to the reaction\nenvironment. Herein, wurtzite-structured crystals such as GaN, ZnO, and AlP are\nfound for developing natural, dense, and stable SFLPs. It is revealed that the\nSFLPs can naturally exist on the (100) and (110) surfaces of\nwurtzite-structured crystals. All the surface cations and anions serve as the\nLewis acid and Lewis base in SFLPs, respectively, contributing to the surface\ndensity of SFLPs as high as 7.26 x 1014 cm-2. Ab initio molecular dynamics\nsimulations indicate that the SFLPs can keep stable under high temperatures and\nthe reaction atmospheres of CO and H2O. Moreover, outstanding performance for\nactivating the given small molecules is achieved on these natural SFLPs, which\noriginates from the optimal orbital overlap between SFLPs and small molecules.\nOverall, these findings not only provide a simple method to obtain dense and\nstable SFLPs but also unfold the nature of SFLPs toward the facile activation\nof small molecules.",
        "positive": "Computational study of (111) epitaxially strained ferroelectric\n  perovskites BaTiO3 and PbTiO3: The phase transition behaviour of PbTiO3 and BaTiO3 under (111) epitaxial\nstrain is investigated using density-functional theory calculations. From\ntensile strains of +0.015 to compressive strains of -0.015, PbTiO3 undergoes\nphase transitions from C2 through two Cm phases and then to R3m. The total\npolarisation is found to be almost independent of strain. For the same range of\nstrains BaTiO3 undergoes phase transitions from a single Cm phase, through R3m\nand then to R-3m. In this case the application of compressive strain inhibits\nand then completely suppresses the polarisation on transition to the non-polar\nR-3m phase."
    },
    {
        "anchor": "Hamiltonian Transformation for Band Structure Calculations: First-principles electronic band structure calculations are essential for\nunderstanding periodic systems in condensed matter physics and materials\nscience. We propose an accurate and parameter-free method, called Hamiltonian\ntransformation (HT), to calculate band structures in both density functional\ntheory (DFT) and post-DFT calculations with plane-wave basis sets. The cost of\nHT is independent of the choice of the density functional and scales as\n$\\mathcal{O}(N_e^3N_k\\log N_k)$, where $N_e$ and $N_k$ are the number of\nelectrons and the number of $\\mathbf{k}$-points. Compared to the widely used\nWannier interpolation (WI), HT adopts an eigenvalue transformation to construct\na spatial localized representation of the spectrally truncated Hamiltonian. HT\nalso uses a non-iterative algorithm to change the basis sets to circumvent the\nconstruction of the maximally localized Wannier functions. As a result, HT can\nsignificantly outperform WI in terms of the accuracy of the band structure\ncalculation. We also find that the eigenvalue transformation can be of\nindependent interest, and can be used to improve the accuracy of the WI for\nsystems with entangled bands.",
        "positive": "Theory of Hysteresis Loop in Ferromagnets: We consider three mechanisms of hysteresis phenomena in alternating magnetic\nfield: the domain wall motion in a random medium, the nucleation and the\nretardation of magnetization due to slow (critical) fluctuations. We construct\nquantitative theory for all these processes. The hysteresis is characterized by\ntwo dynamic threshold fields, by coercive field and by the so-called reversal\nfield. Their ratios to the static threshold field is shown to be function of\ntwo dimensionless variables constituted from the frequency and amplitude of the\nac field as well as from some characteristics of the magnet. The area and the\nshape of the hysteresis loop are found. We consider different limiting cases in\nwhich power dependencies are valid. Numerical simulations show the domain wall\nformation and propagation and confirm the main theoretical predictions. Theory\nis compared with available experimental data."
    },
    {
        "anchor": "Electron-phonon interaction contribution to the total energy of group IV\n  semiconductor polymorphs: evaluation and implications: In density functional theory (DFT) based total energy studies, the van der\nWaals (vdW) and zero-point vibrational energy (ZPVE) correction terms are\nincluded to obtain energy differences between polymorphs. We propose and\ncompute a new correction term to the total energy, due to electron-phonon\ninteractions (EPI). We rely on Allen's general formalism, which goes beyond the\nQuasi-Harmonic Approximation (QHA), to include the free energy contributions\ndue to quasiparticle interactions. We show that, for semiconductors and\ninsulators, the EPI contributions to the free energies of electrons and phonons\nare the corresponding zero-point energy contributions. Using an approximate\nversion of Allen's formalism in combination with the Allen-Heine theory for EPI\ncorrections, we calculate the zero-point EPI corrections to the total energy\nfor cubic and hexagonal polytypes of Carbon, Silicon and Silicon Carbide. The\nEPI corrections alter the energy differences between polytypes. In SiC\npolytypes, the EPI correction term is more sensitive to crystal structure than\nthe vdW and ZPVE terms and is thus essential in determining their energy\ndifferences. It clearly establishes that the cubic SiC-3C is metastable and\nhexagonal SiC-4H is the stable polytype. Our results are consistent with the\nexperimental results of Kleykamp. Our study enables the inclusion of EPI\ncorrections as a separate term in the free energy expression. This opens the\nway to go beyond the QHA by including the contribution of EPI on all\nthermodynamic properties.",
        "positive": "Momentum-resolved observation of exciton formation dynamics in monolayer\n  WS$_2$: The dynamics of exciton formation in transition metal dichalcogenides is\ndifficult to measure experimentally, since many momentum-indirect exciton\nstates are not accessible to optical interband spectroscopy. Here, we combine a\ntuneable pump, high-harmonic probe laser source with a 3D momentum imaging\ntechnique to map photoemitted electrons from monolayer WS$_2$. This provides\nmomentum-, energy- and time-resolved access to excited states on an ultrafast\ntimescale. The high temporal resolution of the setup allows us to trace the\nearly-stage exciton dynamics on its intrinsic timescale and observe the\nformation of a momentum-forbidden dark K$\\Sigma$ exciton a few tens of\nfemtoseconds after optical excitation. By tuning the excitation energy we\nmanipulate the temporal evolution of the coherent excitonic polarization and\nobserve its influence on the dark exciton formation. The experimental results\nare in excellent agreement with a fully microscopic theory, resolving the\ntemporal and spectral dynamics of bright and dark excitons in WS$_2$."
    },
    {
        "anchor": "Teaching Solid Mechanics to Artificial Intelligence: a fast solver for\n  heterogeneous solids: We propose a deep neural network (DNN) as a fast surrogate model for local\nstress (and in principle strain) calculation in inhomogeneous non-linear\nmaterial systems. We show that the DNN predicts the local stresses with about\n3.8% mean absolute percentage error (MAPE) for the case of heterogeneous\nelastic media and a mechanical phase contrast of up to factor of 1.5 among\nneighboring domains, while performing 103 times faster than spectral solvers.\nThe speed-up arises from the fact that after training, the DNN predicts the\nstress without any iterations, as opposed to the iterative nature of standard\nnon-linear solvers. The new DNN surrogate model also proves suited for general\npurposes: it is capable to reproduce the stress distribution in geometries\ntopologically far different from those used for training, implying effective\nlearning of scenarios described by the underlying partial differential\nequations. Even in the case of elasto-plastic materials with up to 2 times\nmechanical contrast in elastic stiffness and 4 times in yield stress among\nadjacent regions, where conventional solvers typically require a substantial\nnumber of iterations to arrive at stress predictions, the trained model\nsimulates the micromechanics with a MAPE of 6.4% in one single forward\nevaluation step of the network, i.e. without any iterative calculations even\nfor the case of such a non-linear problem. The results reveal a completely new\nand highly efficient approach to solve non-linear mechanical boundary value\nproblems and/or augment existing solution methods in corresponding hybrid\nvariants, with an acceleration up to factor of 8300 for heterogeneous\nelastic-plastic materials in comparison to the currently fastest available\nsolvers.",
        "positive": "Decomposition Process of Carboxylate MOF HKUST-1 Unveiled at the Atomic\n  Scale Level: HKUST-1 is a metal-organic framework (MOF) which plays a significant role\nboth in applicative and basic fields of research, thanks to its outstanding\nproperties of adsorption and catalysis but also because it is a reference\nmaterial for the study of many general properties of MOFs. Its metallic group\ncomprises a pair of Cu2+ ions chelated by four carboxylate bridges, forming a\nstructure known as paddle-wheel unit, which is the heart of the material.\nHowever, previous studies have well established that the paddle-wheel is\nincline to hydrolysis. In fact, the prolonged exposure of the material to\nmoisture promotes the hydrolysis of Cu-O bonds in the paddle-wheels, so\nbreaking the crystalline network. The main objective of the present\nexperimental investigation is the determination of the details of the\nstructural defects induced by this process in the crystal and it has been\nsuccessfully pursued by coupling the electron paramagnetic resonance\nspectroscopy with other more commonly considered techniques, as X-ray\ndiffraction, surface area estimation and scanning electron microscopy. Thanks\nto this original approach we have recognized three stages of the process of\ndecomposition of HKUST-1 and we have unveiled the details of the corresponding\nequilibrium structures of the paddle-wheels at the atomic scale level."
    },
    {
        "anchor": "Role of surface waves on the relation between crack speed and the work\n  of fracture: We show that the delivery of fracture work to the tip of an advancing planar\ncrack is strongly reduced by surface phonon emission, leading to forbidden\nranges of crack speed. The emission can be interpreted through dispersion of\nthe group velocity, and Rayleigh and Love branches contribute as well as other\nhigh frequency branches of the surface wave dispersion relations. We also show\nthat the energy release rate which enters the Griffith criterion for the crack\nadvance can be described as the product of the continuum solution with a\nfunction that only depends on the lattice geometry and describes the lattice\ninfluence on the phonon emission. Simulations are performed using a new finite\nelement model for simulating elasticity and fractures. The model, built to\nallow fast and very large three-dimensional simulations, is applied to the\nsimplified case of two dimensional samples.",
        "positive": "Self-Diffusion of Iron in L10 FePd film - as revealed by reflectometric\n  methods: L10 (CuAu(I)-type) ordered FePd as well as FePt and CoPt, due to their high\nmagnetic anisotropy, are candidate materials for future ultra-high density\nmagnetic recording. Atomic diffusion governs the structural relaxation and\nassociated changes in the physical and magnetic properties in these alloys.\nSuch processes involve diffusion paths of a few angstroms. In developing modern\nstorage devices it is indispensable to understand these processes. Neutron\nreflectometry (NR) and Synchrotron M\\\"ossbauer Reflectometry (SMR) are suitable\nnon destructive methods to study self-diffusion in a chemically homogenous\nisotope multilayer with diffusion lengths of the order of a few angstroms. From\nthe diffusion parameters obtained from NR and SMR evaluation we determined\nactivation energies (Q) and preexponent factors (D0) for the distinct\nenvironment in the FePd samples. We obtained the highest activation energy\n(1.82\\pm0.38 eV)and lowest preexponential factor((5.76\\pm0.35)*10-14 m2/s) for\nthe ordered L10 as oppose to the iron rich regions were the activation energy\n(1.48\\pm0.26 \\pmV) found to be lowest and the preexponential factor the highest\n((1.01\\pm0.61)*10-13 m2/s)."
    },
    {
        "anchor": "Topological Phase Transitions and Quantum Hall Effect in the Graphene\n  Family: Monolayer staggered materials of the graphene family present intrinsic\nspin-orbit coupling and can be driven through several topological phase\ntransitions using external circularly polarized lasers, and static electric or\nmagnetic fields. We show how topological features arising from photo-induced\nphase transitions and the quantum Hall effect coexist in these materials, and\nsimultaneously impact their Hall conductivity through their corresponding\ncharge Chern numbers. We also show that the spectral response of the\nlongitudinal conductivity contains signatures about the various phase\ntransition boundaries, that the transverse conductivity encodes information\nabout the topology of the band structure, and that both present resonant peaks\nwhich can be unequivocally associated to one of the four inequivalent Dirac\ncones present in these materials. This complex optoelectronic response can be\nprobed with straightforward Faraday rotation experiments, allowing the study of\nthe crossroads between quantum Hall physics, spintronics, and valleytronics.",
        "positive": "Theory and Applications of X-ray Standing Waves in Real Crystals: Theoretical aspects of x-ray standing wave method for investigation of the\nreal structure of crystals are considered in this review paper. Starting from\nthe general approach of the secondary radiation yield from deformed crystals\nthis theory is applied to different concreat cases. Various models of deformed\ncrystals like: bicrystal model, multilayer model, crystals with extended\ndeformation field are considered in detailes. Peculiarities of x-ray standing\nwave behavior in different scattering geometries (Bragg, Laue) are analysed in\ndetailes. New possibilities to solve the phase problem with x-ray standing wave\nmethod are discussed in the review. General theoretical approaches are\nillustrated with a big number of experimental results."
    },
    {
        "anchor": "Origin of the different conductive behavior in pentavalent-ion-doped\n  anatase and rutile TiO$_2$: The electronic properties of pentavalent-ion (Nb$^{5+}$, Ta$^{5+}$, and\nI$^{5+}$) doped anatase and rutile TiO$_2$ are studied using spin-polarized\nGGA+\\emph{U} calculations. Our calculated results indicate that these two\nphases of TiO$_2$ exhibit different conductive behavior upon doping. For doped\nanatase TiO$_2$, some up-spin-polarized Ti 3\\emph{d} states lie near the\nconduction band bottom and cross the Fermi level, showing an \\emph{n}-type\nhalf-metallic character. For doped rutile TiO$_2$, the Fermi level is pinned\nbetween two up-spin-polarized Ti 3\\emph{d} gap states, showing an insulating\ncharacter. These results can account well for the experimental different\nelectronic transport properties in Nb (Ta)-doped anatase and rutile TiO$_2$.",
        "positive": "Rolling contact fatigue deformation mechanisms of nickel-rich\n  nickel-titanium-hafnium alloys: The tribological performance and underlying deformation behavior of Ni55Ti45,\nNi54Ti45Hf1 and Ni56Ti36Hf8 alloys were studied using rolling contact fatigue\n(RCF) testing and transmission electron microscopy (TEM). TEM results of the\nas-machined RCF rods, prepared using focus ion beam, revealed some damage very\nclose to the surface. TEM results after initial RCF cycling showed that\nadditional damage was mainly confined to deformation bands that propagated\nseveral microns into the sample. These bands formed via localized dislocation\nslip, possibly on multiple slip systems, within the B2 matrix and/or within\ntransformed B19 prime martensite phase under repeated applied contact stress.\nFurther cycling of Ni55Ti45 and Ni54Ti45Hf1 led to shearing and dissolution of\nthe strengthening precipitates within the deformation bands, followed by\nformation of nanocrystalline grains and finally amorphization of the remaining\nmatrix material within the bands. The Ni56Ti36Hf8 alloy exhibited a notable\nincrease in RCF performance and a smaller damage zone (1.5 microns) compared to\nthe Ni55Ti45 and Ni54Ti45Hf1 alloys (over 6 microns). This was attributed to\nthe low fraction of B2 matrix phase (less than or equal to 13 %) in the\nNi56Ti36Hf8 alloy, leading to formation of narrow deformation bands (less than\n11 nm) that were incapable of dissolving the much larger precipitates. Instead,\nthe deformation bands were restricted to narrow channels between the dense\ncubic NiTiHf and H-phase precipitates. In contrast, broad deformation bands\naccompanied by shearing and eventual dissolution of the Ni4Ti3 precipitates\nwere observed in the Ni55Ti45 and Ni54Ti45Hf1 alloys due to the high area\nfractions of B2 matrix phase (~49 %)."
    },
    {
        "anchor": "Monte Carlo Simulation of Melting and Lattice Relaxation of the (111)\n  Surface of Silver: It is experimentally observed and theoretically proved that the distance\nbetween topmost layers of a metal surface has a contraction. However,\nwell-known potentials such as Lennard-Jones and Morse potentials lead to an\nexpansion of the surface inter-layer distance. Such simple potentials therefore\ncannot be used to study metal surface relaxation. In this paper, extensive\nMonte Carlo simulations are used to study the silver (111) surface with both\nthe Gupta potential (GP) and the Embedded Atom Method (EAM) potential. Our\nresults of the lattice relaxation at the (111) surface of silver show indeed a\ncontraction for both potentials at low temperatures in agreement with\nexperiments and early theories. However at higher temperatures, the EAM\npotential yields a surface melting at $\\simeq 700$ K very low with respect to\nthe experimental bulk melting at $\\simeq 1235$ K while the GP yields a surface\nmelting at $\\simeq 1000$ K closer to the bulk one. In addition, we observe with\nthe EAM potential an anomalous thermal expansion, i. e. the surface contraction\nbecomes a surface dilatation with respect to the bulk, at $\\simeq 900$ K. The\nGupta potential does not show this behavior.We compare our results with\ndifferent experimental and numerical results.",
        "positive": "Power law analysis for temperature dependence of magnetocrystalline\n  anisotropy constants of Nd$_2$Fe$_{14}$B magnets: Phenomenological analysis for the temperature dependence of the\nmagnetocrystalline anisotropy (MA) in rare earth magnets is presented. We\ndefine phenomenological power laws applicable to compound magnets using the\nZener theory, apply these laws to the magnetocrystalline anisotropy constants\n(MACs) of Nd$_2$Fe$_{14}$B magnets. The results indicate that the MACs obey the\npower law well, and a general understanding for the temperature-dependent MA in\nrare earth magnets is obtained through the analysis. Furthermore, to examine\nthe validity of the power law, we discuss the temperature dependence of the\nMACs in Dy$_2$Fe$_{14}$B and Y$_2$Fe$_{14}$B magnets as examples wherein it is\ndifficult to interpret the MA using the power law."
    },
    {
        "anchor": "Synthesis of low-moment CrVTiAl: a potential room temperature spin\n  filter: The efficient production of spin-polarized currents at room temperature is\nfundamental to the advancement of spintronics. Spin-filter materials ---\nsemiconductors with unequal band gaps for each spin channel --- can generate\nspin-polarized current without the need for spin-polarized contacts. In\naddition, a spin-filter material with zero magnetic moment would have the\nadvantage of not producing strong fringing fields that would interfere with\nneighboring electronic components and limit the volume density of devices. The\nquaternary Heusler compound CrVTiAl has been predicted to be a zero-moment\nspin-filter material with a Curie temperature in excess of 1000 K. In this\nwork, CrVTiAl has been synthesized with a lattice constant of $a = 6.15 \\AA$.\nMagnetization measurements reveal an exceptionally low moment of $\\mu = 2.3\n\\times 10^{-3} \\mu_B/f.u.$ at a field of $\\mu_0 H = 2 T$, that is independent\nof temperature between T = 10 K and 400 K, consistent with the predicted\nzero-moment ferrimagnetism. Transport measurements reveal a combination of\nmetallic and semiconducting components to the resistivity. Combining a\nzero-moment spin-filter material with nonmagnetic electrodes would lead to an\nessentially nonmagnetic spin injector. These results suggest that CrVTiAl is a\npromising candidate for further research in the field of spintronics.",
        "positive": "Tunable Fluorescein-Encapsulated Zeolitic Imidazolate Framework-8\n  Nanoparticles for Solid-State Lighting: A series of fluorescein-encapsulated zeolitic imidazolate framework-8\n(fluorescein@ZIF-8) luminescent nanoparticles with a scalable guest loading has\nbeen fabricated and characterized. The successful encapsulation of the organic\ndye (fluorescein) is supported by both experimental evidence and theoretical\nsimulations. The measured optical band gap is found to be comparable with the\ncomputed values of a hypothetical guest-host system. Isolated monomers and\naggregates species of fluorescein confined in ZIF-8 nanocrystals have been\nsystematically investigated through fluorescence lifetime spectroscopy. The\nquantum yield (QY) of the obtained solid-state materials is particularly high\n(QY~98%), especially when the concentration of the fluorescein guest is low.\nCombining a blue LED chip and a thin photoactive film of fluorescein@ZIF-8, we\ndemonstrate a device with good optical tunability for multicolor and white\nlight emissions. Additionally, we show that the fluorescein@ZIF-8 nanoparticles\nexhibit an improved photostability due to the shielding effect conferred by the\nnanoconfinement of host framework, making them promising candidates for\npractical applications such as solid-state lighting, photonics, and optical\ncommunications."
    },
    {
        "anchor": "Non-Classical Crystal Growth Recipe using nanocrystalline ceria a\n  detailed review: In this review, room temperature (RT) precipitation of the\nnanocrystalline-ceria (nc-ceria) re-dispersed and subsequently size-reduced by\n20 kHz probe sonication in 25 % ethylene glycol/ 75 % DI-water mixed media is\ninvestigated. The sonication result in three nanostructured products: (1)\nwater-soluble supernatant nc-ceria (Ce_Sl@RT), (2) settled gelatinous nc-ceria\nmass (Ce_SS@RT), and (3) ambient dried nc-ceria solid powder (Ce_SP@RT) product\nalong with the parent RT nc-ceria (Ce@RT) precipitates. Surface/interface\nattributes are investigated systematically with the help of suitable\nspectroscopic probes. By following this synthesis protocol, the nc-ceria is\nmade to cohabit with a variety (water, ethylene glycol, air) of neighbors that\nlead to the distinct surface and interface termination. The physical and\nchemical aspects of these varieties of the specialized surface terminated\nnc-ceria are explored coherently with respect to the Ce@RT precipitate. The\nsecond aspect of this review is devoted to the biomineralization for which the\nsonication derived Ce_Sl@RT is the candidate of choice. Aging of Ce_Sl@RT is\nphysically tracked to mimic the natural aquatic medium crystal growth by the\nbiomineralization process. In-situ TEM is extensively used to demonstrate the\nnon-classical crystal growth mechanism physically. Uniquely TEM electron beam\n(e-beam) is exploited to aid both in the material manipulation and probing.",
        "positive": "Topological Electronic States in HfRuP Family Superconductors: Based on the first-principles calculations and experimental measurements, we\nreport that the hexagonal phase of ternary transition metal pnictides TT'X\n(T=Zr, Hf; T'=Ru; X=P, As), which are well-known noncentrosymmetric\nsuperconductors with relatively high transition temperatures, host nontrivial\nbulk topology. Before the superconducting phase transition, we find that HfRuP\nbelongs to a Weyl semimetal phase with 12 pairs of type-II Weyl points, while\nZrRuAs, ZrRuP and HfRuAs belong to a topological crystalline insulating phase\nwith trivial Fu-Kane $\\mathbb Z_2$ indices but $nontrivial$ mirror Chern\nnumbers. High-quality single crystal samples of the noncentrosymmetric\nsuperconductors with these two different topological states have been obtained\nand the superconductivity is verified experimentally. The wide-range band\nstructures of ZrRuAs have been identified by ARPES and reproduced by\ntheoretical calculations. Combined with intrinsic superconductivity, the\nnontrivial topology of the normal state may generate unconventional\nsuperconductivity in both bulk and surfaces. Our findings could largely inspire\nthe experimental searching for possible topological superconductivity in these\ncompounds."
    },
    {
        "anchor": "Carrier diffusion in GaN -- a cathodoluminescence study. I:\n  Temperature-dependent generation volume: The determination of the carrier diffusion length of semiconductors such as\nGaN and GaAs by cathodoluminescence imaging requires accurate knowledge about\nthe spatial distribution of generated carriers. To obtain the lateral\ndistribution of generated carriers for sample temperatures between 10 and 300\nK, we utilize cathodoluminescence intensity profiles measured across single\nquantum wells embedded in thick GaN and GaAs layers. Thin (Al,Ga)N and\n(Al,Ga)As barriers, respectively, prevent carriers diffusing in the GaN and\nGaAs layers to reach the well, which would broaden the profiles. The\nexperimental cathodoluminescence profiles are found to be systematically wider\nthan the energy loss distributions calculated by means of the Monte Carlo\nprogram CASINO, with the width monotonically increasing with decreasing\ntemperature. This effect is observed for both GaN and GaAs and becomes more\npronounced for higher acceleration voltages. We discuss this phenomenon in\nterms of both, the electron-phonon interaction controlling the energy\nrelaxation of hot carriers, and the shape of the initial carrier distribution.\nFinally, we present a phenomenological approach to simulate the carrier\ngeneration volume that can be used for the investigation of the temperature\ndependence of carrier diffusion.",
        "positive": "Cluster Catalysis with Lattice Oxygen: Tracing Oxygen Transport from a\n  Magnetite(001) Support onto Small Pt Clusters: Oxidation catalysis on reducible oxide-supported small metal clusters often\ninvolves lattice oxygen. In the present work, we trace the path of lattice\noxygen from Fe3O4(001) onto small Pt clusters during the CO oxidation, aiming\nat differentiating whether the reaction takes place at the cluster/support\ninterface or on the cluster. While oxygen vacancies form on many other\nsupports, magnetite maintains its surface stoichiometry upon reduction thanks\nto a high cation mobility. In order to investigate whether size-dependent\noxygen affinities play a role, we study two specific cluster sizes, Pt5 and\nPt19. By separating different reaction steps in our experiment, lattice oxygen\ncan be accumulated on the clusters. Temperature programmed desorption (TPD) and\nsophisticated pulsed valve experiments indicate that the CO oxidation takes\nplace on the Pt clusters rather than at the interface. Scanning tunneling\nmicroscopy (STM) shows a decrease in apparent height of the clusters, which\ndensity functional theory (DFT) explains as a restructuring following lattice\noxygen reverse spillover."
    },
    {
        "anchor": "Uncovering A Two-Dimensional Semiconductor with Intrinsic Ferromagnetism\n  at Room Temperature: Two-dimensional materials have been gaining great attention as they displayed\na broad series of electronic properties that ranging from superconductivity to\ntopology. Among them, those which possess magnetism are most desirable,\nenabling us to manipulate charge and spin simultaneously. Here, based on\nfirst-principles calculation, we demonstrate monolayer chromium iodide arsenide\n(CrIAs), an undiscovered stable two-dimensional material, is an intrinsic\nferromagnetic semiconductor with out-of-plane spin magnetization. The indirect\nbandgaps are predicted to be 0.32 eV for majority spin and 3.31 eV for minority\nspin, large enough to preserve semiconducting features at room temperature. Its\nCurie temperature, estimated by Heisenberg model with magnetic anisotropic\nenergy using Monte Carlo method, is as high as 655 K that well above the room\ntemperature, owing to strong direct exchange interaction between chromium d and\niodine p orbitals. This work offers the affirmative answer of whether there\nexists two-dimensional ferromagnetic semiconductor at room temperature. And the\npractical realization of quantum spintronic devices, which have been suppressed\nbecause of lacking suitable room temperature magnetic materials, would embrace\na great opportunity.",
        "positive": "Development and properties of composite cement reinforced coconut fiber\n  with the addition of fly ash: In this paper, the effectiveness utilization of agriculture wastes and\nindustrial wastes in the composites cement has been studied in terms of\nphysical and mechanical properties. Twenty weight percent of fly ash and eighty\nweight percent of sand were added to the composite cement. The different weight\npercent of coconut fiber (3 wt. %, 6 wt. %, 9 wt. %, 12 wt. % and 15 wt. %) was\nadded in the composition as reinforcement for cement composites. Water to\ncement ratio ranging from 0.55 to 0.70 was added into the cement composites\naccordingly to maintain its workability. Then the cement composites were cured\nin water for 7, 14 and 28 days respectively. Results for physical properties\n(density, moisture content, water absorption) and mechanical properties\n(compressive strength, modulus of rupture) are presented."
    },
    {
        "anchor": "The first-principles study of thermodynamical properties of random\n  magnetic overlayers on fcc-Cu(001) substrate: We present the theoretical study of thermodynamical properties of fcc-Cu(001)\nsubstrate covered by iron-cobalt monolayer as well as by incomplete iron layer.\nThe effective two-dimensional Heisenberg Hamiltonian is constructed from first\nprinciples and properties of exchange interactions are investigated. The Curie\ntemperatures are estimated using the Monte-Carlo (MC) simulations and compared\nwith a simplified approach using the random-phase approximation (RPA) in\nconnection with the virtual-crystal approach (VCA) to treat randomness in\nexchange integrals. Calculations indicate a weak maximum of the Curie\ntemperature as a function of composition of the iron-cobalt overlayer. While a\ngood quantitative agreement between RPA-VCA and MC was found for iron-cobalt\nmonolayer, the RPA-VCA approach fails quantitatively for low coverage due to\nthe magnetic percolation effect. We also present the study of the effect of\nalloy disorder on the shape of magnon spectra of random overlayers.",
        "positive": "Difference between thermo- and pyroelectric Co- based RE-(= Nd, Y, Gd,\n  Ce)-oxide composites measured by high-temperature gradient: Seebeck-Voltage measurements of Cobalt-based oxide-composites containing\nrare-earth elements (RE= Nd, Y, Gd, Ce) were performed under high temperature\ngradients up to 700 K. Several dependences were measured, Seebeeck voltage as a\nfunction of time U_S(t)or temperature difference U_S(Delta_T), closed circuited\nelectric current as a function of Seebeck voltage I_S(U_S), or time I_S(t).\nWhile Nd2O3+CoO and Y2O3+CoO show linear n-type US(t)-behavior as usual\nthermoelectrics, Gd2O3+CoO possesses a large hysteresis. At both, Gd2O3- and\nCe2O3+CoO also large time dependence I(t) referred to as pyroelectric material\nwith high capacity were detected. Both anomalies became smaller when Fe2O3 is\nadded or appear in Nd2O3+CoO and Y2O3+CoO when Al2O3 is added and can be\nexplained by electron sucking into interfacial space charge regions, a new\nmaterials science challenge."
    },
    {
        "anchor": "Formation of yttrium oxalate phase filled by carbon clusters on the\n  surface of yttrium oxide films: In the current paper, we report the results of surface modification of cubic\nY2O3 films employing carbon-ion implantation. The characterization results\ndemonstrate the formation of a stable yttrium oxalate-based structure with\ncavities filled with carbon clusters. Theoretical simulations demonstrate that\nthe incorporation of eighteen-atom carbon clusters into the cavities of\nY2(C2O4)3 does not lead to valuable changes in the crystal structure of yttrium\noxalate. X-ray diffraction and optical measurements demonstrate that the\nsubsurface bulk area of cubic yttrium oxide remains unperturbed. The oxalate\n\"skin\" thickness with embedded carbon clusters is estimated to be approximately\n10 nm. The prospective employing the method to manage optical properties and\nincrease the biocompatibility of yttria and lanthanide oxides are discussed.",
        "positive": "Self-phase modulation of a single-cycle terahertz pulse by nonlinear\n  free-carrier response in a semiconductor: We demonstrate the self-phase modulation (SPM) of a single-cycle THz pulse in\na semiconductor, using bulk n-GaAs as a model system. The SPM arises from the\nheating of free electrons in the electric field of the THz pulse, leading to an\nultrafast reduction of the plasma frequency, and hence to a strong modification\nof the THz-range dielectric function of the material. THz SPM is observed\ndirectly in the time domain. In the frequency domain it corresponds to a strong\nfrequency-dependent refractive index nonlinearity of n-GaAs, found to be both\npositive and negative within the broad THz pulse spectrum, with the\nzero-crossing point defined by the electron momentum relaxation rate. We also\nobserved the nonlinear spectral broadening and compression of the THz pulse."
    },
    {
        "anchor": "Thermal van der Waals Interaction between Graphene Layers: The van de Waals interaction between two graphene sheets is studied at finite\ntemperatures. Graphene's thermal length $(\\xi_T = \\hbar v / k_B T)$ controls\nthe force versus distance $(z)$ as a crossover from the zero temperature\nresults for $z\\ll \\xi_T$, to a linear-in-temperature, universal regime for\n$z\\gg \\xi_T$. The large separation regime is shown to be a consequence of the\nclassical behavior of graphene's plasmons at finite temperature. Retardation\neffects are largely irrelevant, both in the zero and finite temperature\nregimes. Thermal effects should be noticeable in the van de Waals interaction\nalready for distances of tens of nanometers at room temperature.",
        "positive": "Ab-initio study of short-range ordering in vanadium-based disordered\n  rocksalt structures: Disordered rocksalt Li-excess (DRX) compounds are attractive new cathode\nmaterials for Li-ion batteries as they contain resource-abundant metals and do\nnot require the use of cobalt or nickel. Understanding the delithiation process\nand cation short-range ordering (SRO) in DRX compounds is essential to\nimproving these promising cathode materials. Herein, we use first-principles\ncalculations along with the cluster-expansion approach to model the disorder in\nDRX Li2-xVO3, 0 < x < 1. We discuss the SRO of Li in tetrahedral and octahedral\nsites, and the order in which Li delithiates and V oxidizes with respect to\nlocal environments. We reveal that the number of nearest-neighbor V dictates\nthe order of delithiation from octahedral sites and that V are oxidized in a\nmanner that minimizes the electrostatic interactions among V. Our results\nprovide valuable insight for tailoring the performance of V-based DRX cathode\nmaterials in general by controlling the SRO features that reduce energy\ndensity."
    },
    {
        "anchor": "Large magnetic circular dichroism in resonant inelastic x-ray scattering\n  at the Mn L-edge of Mn-Zn ferrite: We report resonant inelastic x-ray scattering (RIXS) excited by circularly\npolarized x-rays on Mn-Zn ferrite at the Mn L2,3-resonances. We demonstrate\nthat crystal field excitations, as expected for localized systems, dominate the\nRIXS spectra and thus their dichroic asymmetry cannot be interpreted in terms\nof spin-resolved partial density of states, which has been the standard\napproach for RIXS dichroism. We observe large dichroic RIXS at the L2-resonance\nwhich we attribute to the absence of metallic core hole screening in the\ninsulating Mn-ferrite. On the other hand, reduced L3-RIXS dichroism is\ninterpreted as an effect of longer scattering time that enables spin-lattice\ncore hole relaxation via magnons and phonons occurring on a femtosecond time\nscale.",
        "positive": "Evidence of breakdown of the spin symmetry in diluted 2D electron gases: Recent claims of an experimental demonstration of spontaneous spin\npolarisation in dilute electron gases \\cite{young99} revived long standing\ntheoretical discussions \\cite{ceper99,bloch}. In two dimensions, the\nstabilisation of a ferromagnetic fluid might be hindered by the occurrence of\nthe metal-insulator transition at low densities \\cite{abra79}. To circumvent\nlocalisation in the two-dimensional electron gas (2DEG) we investigated the low\npopulated second electron subband, where the disorder potential is mainly\nscreened by the high density of the first subband. This letter reports on the\nbreakdown of the spin symmetry in a 2DEG, revealed by the abrupt enhancement of\nthe exchange and correlation terms of the Coulomb interaction, as determined\nfrom the energies of the collective charge and spin excitations. Inelastic\nlight scattering experiments and calculations within the time-dependent local\nspin-density approximation give strong evidence for the existence of a\nferromagnetic ground state in the diluted regime."
    },
    {
        "anchor": "Microstructural engineering of medium entropy NiCo(CrAl) alloy for\n  enhanced room and high-temperature mechanical properties: This work demonstrates the development of a strong and ductile medium entropy\nalloy by employing conventional alloying and thermomechanical processing to\ninduce partial recrystallization (PR) and precipitation strengthening in the\nmicrostructure. The combined usage of electron microscopy and atom probe\ntomography reveals the sequence of microstructural evolution during the\nprocess. First, the cold working of homogenized alloy resulted in a highly\ndeformed microstructure. On annealing at 700{\\deg}C, B2 ordered precipitates\nheterogeneously nucleate on the highly misoriented sites. These B2 promotes\nparticle stimulated nucleation (PSN) of new recrystallized strain-free grains.\nThe migration of recrystallized grain boundaries leads to discontinuous\nprecipitation of L12 ordered regions in highly dense lamellae structures.\nAtomic-scale compositional analysis reveals a significant amount of Ni confined\nto the GB regions between B2 and L12 precipitates, indicating Ni as a\nrate-controlling element for coarsening the microstructure. On 20 hours of\nannealing, the alloy comprises a composite microstructure of soft\nrecrystallized and hard non-recrystallized zones, B2 particles at the grain\nboundaries (GBs), and coherent L12 precipitates inside the grains. The B2 pins\nthe GB movement during recrystallization while the latter provides high\nstrength. The microstructure results in a 0.2% yield stress (YS) value of 1030\nMPa with 32% elongation at ambient temperature and retains up to 910 MPa at\n670{\\deg}C. Also, it shows exceptional microstructural stability at 700 {\\deg}C\nand resistance to deformation at high temperatures up to 770{\\deg}C.\nExamination of deformed microstructure reveals excessive twinning, formation of\nstacking faults, shearing of L12 precipitates, and accumulation of dislocations\nat around the B2 precipitates and GBs attributed to high strain hardening of\nthe alloy.",
        "positive": "Cost-effective search for lower-error region in material parameter space\n  using multifidelity Gaussian process modeling: Information regarding precipitate shapes is critical for estimating material\nparameters. Hence, we considered estimating a region of material parameter\nspace in which a computational model produces precipitates having shapes\nsimilar to those observed in the experimental images. This region, called the\nlower-error region (LER), reflects intrinsic information of the material\ncontained in the precipitate shapes. However, the computational cost of LER\nestimation can be high because the accurate computation of the model is\nrequired many times to better explore parameters. To overcome this difficulty,\nwe used a Gaussian-process-based multifidelity modeling, in which training data\ncan be sampled from multiple computations with different accuracy levels\n(fidelity). Lower-fidelity samples may have lower accuracy, but the\ncomputational cost is lower than that for higher-fidelity samples. Our proposed\nsampling procedure iteratively determines the most cost-effective pair of a\npoint and a fidelity level for enhancing the accuracy of LER estimation. We\ndemonstrated the efficiency of our method through estimation of the interface\nenergy and lattice mismatch between MgZn2 and {\\alpha}-Mg phases in an Mg-based\nalloy. The results showed that the sampling cost required to obtain accurate\nLER estimation could be drastically reduced."
    },
    {
        "anchor": "Visible light enhanced field effect at LaAlO3/SrTiO3 interface: Electrical field and light-illumination have been two most widely used\nstimuli in tuning the conductivity of semiconductor devices. Via capacitive\neffect electrical field modifies the carrier density of the devices, while\nlight-illumination generates extra carriers by exciting trapped electrons into\nconduction band1. Here, we report on an unexpected light illumination enhanced\nfield effect in a quasi-two-dimensional electron gas (q2DEG) confined at the\nLaAlO3/SrTiO3 (LAO/STO) interface which has been the focus of emergent\nphenomenon exploration2-14. We found that light illumination greatly\naccelerates and amplifies the field effect, driving the field-induced\nresistance growth which originally lasts for thousands of seconds into an\nabrupt resistance jump more than two orders of magnitude. Also, the\nfield-induced change in carrier density is much larger than that expected from\nthe capacitive effect, and can even be opposite to the conventional\nphotoelectric effect. This work expands the space for novel effect exploration\nand multifunctional device design at complex oxide interfaces.",
        "positive": "Characterization of the Spin-1/2 Linear-Chain Ferromagnet CuAs$_2$O$_4$: The magnetic and lattice properties of the $S$=1/2 quantum-spin-chain\nferromagnet, CuAs$_2$O$_4$, mineral name trippkeite, were investigated. The\ncrystal structure of CuAs$_2$O$_4$ is characterized by the presence of\ncorrugated CuO$_2$ ribbon chains. Measurements of the magnetic susceptibility,\nheat capacity, electron paramagnetic resonance and Raman spectroscopy were\nperformed. Our experiments conclusively show that a ferromagnetic transition\noccurs at $\\sim$7.4 K. $\\textit{Ab initio}$ DFT calculations reveal dominant\nferromagnetic nearest-neighbor and weaker antiferromagnetic next-\nnearest-neighbor spin exchange interactions along the ribbon chains. The ratio\nof $J_{\\rm nn}$/$J_{\\rm nnn}$ is near -4, placing CuAs$_2$O$_4$ in close\nproximity to a quantum critical point in the $J_{\\rm nn}$ - $J_{\\rm nnn}$ phase\ndiagram. TMRG simulations used to analyze the magnetic susceptibility confirm\nthis ratio. Single-crystal magnetization measurements indicate that a magnetic\nanisotropy forces the Cu$^{2+}$ spins to lie in an easy plane perpendicular to\nthe $c$-axis. An analysis of the field and temperature dependent magnetization\nby modified Arrott plots reveals a 3d-XY critical behavior. Lattice\nperturbations induced by quasi-hydrostatic pressure and temperature were mapped\nvia magnetization and Raman spectroscopy."
    },
    {
        "anchor": "Observation of a topologically non-trivial surface state in half-Heusler\n  PtLuSb (001) thin films: The discovery of topological insulators (TIs), materials with bulk band gaps\nand protected cross-gap surface states, in compounds such as Bi2Se3 has\ngenerated much interest in identifying topological surface states (TSSs) in\nother classes of materials. In particular, recent theory calculations suggest\nthat TSSs may be found in half-Heusler ternary compounds. If experimentally\nrealizable, this would provide a materials platform for entirely new\nheterostructure spintronic devices that make use of the structurally-identical\nbut electronically-varied nature of Heusler compounds. Here, we show the\npresence of a TSS in epitaxially grown thin films of the half-Heusler compound\nPtLuSb. Spin and angle-resolved photoemission spectroscopy (ARPES),\ncomplemented by theoretical calculations, reveals a surface state with linear\ndispersion and a helical tangential spin texture consistent with previous\npredictions. This experimental verification of TI behavior is a significant\nstep forward in establishing half-Heusler compounds as a viable material system\nfor future spintronics devices.",
        "positive": "Excitation energy dependent Raman spectrum of MoSe2: Raman investigation of MoSe2 was carried out with eight different excitation\nenergies. Seven peaks, including E1g, A1g, E2g1, and A2u2 peaks are observed in\nthe range of 100-400 cm-1. The phonon modes are assigned by comparing the peak\npositions with theoretical calculations. The intensities of the peaks are\nenhanced at different excitation energies through resonance with different\noptical transitions. The A1g mode is enhanced at 1.58 and 3.82 eV, which are\nnear the A exciton energy and the band-to-band transition between higher energy\nbands, respectively. The E2g1 mode is strongly enhanced with respect to the A1g\nmode for the 2.71- and 2.81-eV excitations, which are close to the C exciton\nenergy. The different enhancements of the A1g and E2g1 modes are explained in\nterms of the symmetries of the exciton states and the exciton-phonon coupling.\nOther smaller peaks including E1g and A2u2 are forbidden but appear due to the\nresonance effect near optical transition energies."
    },
    {
        "anchor": "Influence of oxygen partial pressure on structural, transport and\n  magnetic properties of Co doped TiO2 films: Thin films of Co-TiO2 are deposited on silicon and quartz substrates using\nPulse Laser Deposition (PLD) process at various oxygen partial pressures\nranging from 6.6 x 10-3 Pascals (Pa) to 53 Pa. Crystal structure, transport and\nmagnetic properties of reduced CoxTi(1-x)O2 (0 <x< 0.03) thin films are\ninvestigated and are found to have a strong dependence on the oxygen partial\npressure. X-ray diffraction (XRD) data reveals the presence of mixed phase\nmaterial containing both anatase and rutile. However, these phases\nintertransform with the change in the oxygen partial pressure in the chamber\nduring the growth of the films. X-ray Photoelectron Spectroscopy (XPS) shows no\nCo or CoO related peaks for samples with Co concentration up to x=0.03.\nHowever, the oxygen 1s peaks are asymmetric suggesting the presence of oxygen\nvacancies. The transport and magnetic measurements show a clear dependence on\nthe concentration of oxygen vacancies. There is an enhancement in the\nelectrical conductivity and the magnetization as more vacancies are created in\nthe material. The resistivity as a function of temperature rho(T) follows the\npolaronic behavior and the activation energies obtained, ~100 to 150meV, are\nwithin the range that is typical for semiconducting materials.",
        "positive": "Quasi-Spin Ising Model and Monte Carlo Simulation of Ferroelastic Phase\n  Transition: 3D Diffuse Scattering and Displacement Short-Range Ordering in\n  Pre-Martensitic State: A quasi-spin Ising model of ferroelastic phase transition is developed and\nemployed to perform atomic-scale Monte Carlo simulation of thermoelastic\nmartensitic transformation. The quasi-spin variable associated with the lattice\nsites characterizes the local unit cells of the orientation variants of the\nground-state martensite phase, which interact with each other through\nlong-range elastic interactions. The simulation study focuses on the intrinsic\nbehaviors of a defect-free crystal that undergoes cubic-to-tetragonal\nmartensitic transformation. It is shown that the diffuse scattering in the\npre-martensitic austenite state results from the spatial correlation of the\natomic-scale heterogeneous lattice displacements and manifests the displacement\nshort-range ordering. The effects of temperature, elastic anisotropy, and shear\nmodulus softening on the diffuse scattering and displacement short-range\nordering are investigated. It is found that elastic softening in the shear\nmodulus C'=(C11-C12)/2 promotes <110>|<1-10> displacement plane waves that\nstabilize the cubic austenite phase through increased entropy, decreasing the\nmartensitic transformation temperature. The simulated diffuse scattering is\ncompared and agrees with the complementary synchrotron X-ray single-crystal\ndiffuse scattering experiment."
    },
    {
        "anchor": "A coupled mixed-mode cohesive zone model: An extension to\n  three-dimensional contact problems: In this study a phenomenological three-dimensional coupled (3DC) mixed-mode\ncohesive zone model (CZM) is proposed. This is done by extending an improved\nversion of the well established exponential CZM of Xu and Needleman (XN) to 3D\ncontact problems. Coupled traction-separation relationships are individually\npresented for normal and transverse directions. The proposed model preserves\nall the essential features of the XN model and yet correctly describes\nmixed-mode separation and in particular mixed-mode closure conditions.\nMoreover, it provides the possibility to explicitly account for all three\ncomponents of the gap function, i.e. separations in different directions. The\n3DC model has some independent parameters, i.e. interface properties, similar\nto the XN model. All the cohesive zone parameters can be determined using\nmode-I and mode-II experiments.",
        "positive": "Universality of Avalanche Exponents in Plastic Deformation of Disordered\n  Solids: Plastic yield of amorphous solids occurs by power law distributed slip\navalanches whose universality is still debated. Determination of the power law\nexponents from experiments and molecular dynamics simulations is hampered by\nlimited statistical sampling. On the other hand, while existing elasto-plastic\ndepinning models give precise exponent values, these models to date have been\nlimited to a scalar approximation of plasticity which is difficult to reconcile\nwith the statistical isotropy of amorphous materials. Here we introduce for the\nfirst time a fully tensorial mesoscale model for the elasto-plasticity of\ndisordered media that can not only reproduce a wide variety of shear band\npatterns observed experimentally for different deformation modes, but also\ncaptures the avalanche dynamics of plastic flow in disordered materials. Slip\navalanches are characterized by universal distributions which are\nquantitatively different from mean field predictions, both regarding the\nexponents and regarding the form of the scaling functions, and which are\nindependent of system dimensionality (2D vs 3D), boundary and loading\nconditions, and uni-or biaxiality of the stress state. We also measure average\navalanche shapes, which are equally universal and inconsistent with mean field\npredictions. Our results provide strong evidence that the universality class of\nplastic yield in amorphous materials is distinct from that of mean field\ndepinning."
    },
    {
        "anchor": "Ab initio screening of metallic MAX ceramics for advanced interconnect\n  applications: The potential of a wide range of layered ternary carbide and nitride MAX\nphases as conductors in interconnect metal lines in advanced CMOS technology\nnodes has been evaluated using automated first principles simulations based on\ndensity functional theory. The resistivity scaling potential of these\ncompounds, i.e. the sensitivity of their resistivity to reduced line\ndimensions, has been benchmarked against Cu and Ru by evaluating their\ntransport properties within a semiclassical transport formalism. In addition,\ntheir cohesive energy has been assessed as a proxy for the resistance against\nelectromigration and the need for diffusion barriers. The results indicate that\nnumerous MAX phases show promise as conductors in interconnects of advanced\nCMOS technology nodes.",
        "positive": "Planar buckling controlled optical conductivity of SiC monolayer from\n  Deep-UV to visible light region: A first-principles study: The electrical and optical properties of flat and planar buckled siligraphene\n(SiC) monolayer are examined using a first principles approach. Buckling\nbetween the Si and the C atoms in SiC structures influences and impacts the\nproperties of the 2D nanomaterial, according to our results. The electron\ndensity of a planar SiC monolayer is calculated, as well as the effects of\nbuckling on it. According to our findings, a siligraphene monolayer is a\nsemiconductor nanomaterial with a direct electronic band gap that decreases as\nthe planar buckling rises. The contributions to the density of states differ\nowing to changes in the system's structure. Another explanation is that planar\nbuckling reduces the sp$^2$ overlapping, breaking the bond symmetry causing it\nto become a sp$^3$ bond. We show that increased planar buckling between the Si\nand the C atoms alters the monolayer's optical, mechanical, and thermal\nproperties. A managed planar buckling increases the optical conductivity with a\nsignificant shift in the far visible range, as all optical spectra features are\nred shifted, still remaining visible. Instead of a $\\sigma\\text{-}\\sigma$\ncovalent bond, the sp$^3$ hybridization produces a stronger $\\sigma\\text{-}\\pi$\nbond. Optical characteristics such as the dielectric function, the absorbance,\nand the optical conductivity of a SiC monolayer are investigated for both\nparallel and perpendicular polarization of the incoming electric field for both\nflat and planar buckled systems. The findings show that the optical properties\nare influenced for both of these two polarizations, with a significant change\nin the optical spectrum from the near visible to the far visible. The ability\nto manipulate the optical and electrical characteristics of this critical 2D\nmaterial through planar buckling opens up new technological possibilities,\nespecially for optoelectronic devices."
    },
    {
        "anchor": "Optimal Design of Layered Periodic Composites for Mitigation of\n  Impact-Induced Elastic Waves: A systematic method for optimal design of layered periodic composites for\nmitigation of impact-induced shock waves is presented. Frequency spectrum of a\npulse with a sharp rise-time is analyzed and the frequency range that carries\nmost of the pulse energy is identified. A genetic algorithm is used to maximize\nthe stop bands of a layered periodic composite over the target frequency range.\nDue to reflection of the pulse over the stop bands, the maximum stress and the\nenergy of transmitted pulse become minimal. To verify the theoretical\ncalculation a sample is fabricated and Hopkinson bar experiments are performed.\nIt is observed that only 9.7% of energy of the incident pulse gets transmitted\nthrough the sample. In addition, the wave speed in the composite is measured to\nbe 45.4% less than the wave speed in its constituent material with the lowest\nwave speed.",
        "positive": "Sigma-phase in Fe-Cr and Fe-V alloy systems and its physical properties: A review is presented on physical properties of the sigma-phase in Fe-Cr and\nFe-V alloy systems as revealed both with experimental -- mostly with the\nMossbauer spectroscopy -- and theoretical methods. In particular, the following\nquestions relevant to the issue have been addressed: identification of sigma\nand determination of its structural properties, kinetics of alpha-to-sigma and\nsigma-to-alpha phase transformations, Debye temperature and Fe-partial phonon\ndensity of states, Curie temperature and magnetization, hyperfine fields,\nisomer shifts and electric field gradients."
    },
    {
        "anchor": "Infrared Reflectance Spectrum of BN Calculated from First Principles: Using the linear response theory, the vibrational and dielectric properties\nare calculated for c-BN, w-BN and h-BN. Calculations of the zone-center\noptical-mode frequencies (including LO-TO splittings) are reported. All optic\nmodes are identified and agreement of theory with experiment is excellent. The\nstatic dielectric tensor is decomposed into contributions arising from\nindividual infrared-active phonon modes. It is found that all of the structures\nhave a smaller lattice dielectric constant than that of electronic\ncontribution. Finally, the infrared reflectance spectrums are presented. Our\ntheoretical results indicate that w-BN shows a similar reflectivity spectrum as\nc-BN. It is difficult to tell the wurtzite structure from the zinc blende phase\nby IR spectroscopy.",
        "positive": "Enhancement of the Binding Energy of Charged Excitons in Disordered\n  Quantum Wires: Negatively and positively charged excitons are identified in the\nspatially-resolved photoluminescence spectra of quantum wires. We demonstrate\nthat charged excitons are weakly localized in disordered quantum wires. As a\nconsequence, the enhancement of the \"binding energy\" of a charged exciton is\ncaused, for a significant part, by the recoil energy transferred to the\nremaining charged carrier during its radiative recombination. We discover that\nthe Coulomb correlation energy is not the sole origin of the \"binding energy\",\nin contrast to charged excitons confined in quantum dots."
    },
    {
        "anchor": "Crystal structure of synthetic Mg3Cr2Si3O12, the high-pressure Cr\n  end-member of the knorringite-pyrope garnet series: Knorringite, the Cr-end-member of the pyrope garnet series (Nixon et al.\n1968), often occur in high proportions in kimberlite garnets and is thus used\nfor tracing high-pressure deep-earth conditions favorable to the formation of\ndiamonds, in which knorringite-rich garnet can occur as inclusions. However,\nalthough the synthesis of knorringite is reported in the literature (Ringwood\n1977; Irifune et al. 1982; Taran et al. 2004), the structure of the pure\nend-member has not been yet determined from experimental data. In this study,\nthe crystal structure of knorringite, Mg3Cr2(SiO4)3, has been refined from high\nresolution synchrotron X-ray powder diffraction data recorded under ambient\nconditions on a polycrystalline sample synthesized at 12 GPa in a multi-anvil\napparatus. The structure is cubic, space group Ia-3d, a = 11.5935(1), V =\n1558.27(4) {\\AA}3, dcalc = 3.97 g.cm-3. The Cr-O distance of 1.957(2) {\\AA} is\nconsistent with EXAFS results on the same sample. This short distance indicates\na substantial compression of the CrO6 octahedron, compared to ambient pressure\nCr3+-minerals such as uvarovite (<Cr-O> = 1.99 {\\AA}, Andrut and Wildner 2002).\nOur experimental results thus confirm early empirical predictions based on\nseries of high-pressure Cr-garnet end-members (Fursenko 1981), showing that the\nvalues of the Cr-O distance and the Cr-O-Si angle decrease with the\naugmentation of pressure and with the diminution of the size of the divalent\ncation.",
        "positive": "Continuum dynamics of the formation, migration and dissociation of\n  self-locked dislocation structures on parallel slip planes: In continuum models of dislocations, proper formulations of short-range\nelastic interactions of dislocations are crucial for capturing various types of\ndislocation patterns formed in crystalline materials. In this article, the\ncontinuum dynamics of straight dislocations distributed on two parallel slip\nplanes is modelled through upscaling the underlying discrete dislocation\ndynamics. Two continuum velocity field quantities are introduced to facilitate\nthe discrete-to-continuum transition. The first one is the local migration\nvelocity of dislocation ensembles which is found fully independent of the\nshort-range dislocation correlations. The second one is the decoupling velocity\nof dislocation pairs controlled by a threshold stress value, which is proposed\nto be the effective flow stress for single slip systems. Compared to the almost\nubiquitously adopted Taylor relationship, the derived flow stress formula\nexhibits two features that are more consistent with the underlying discrete\ndislocation dynamics: i) the flow stress increases with the in-plane component\nof the dislocation density only up to a certain value, hence the derived\nformula admits a minimum inter-dislocation distance within slip planes; ii) the\nflow stress smoothly transits to zero when all dislocations become\ngeometrically necessary dislocations. A regime under which inhomogeneities in\ndislocation density grow is identified, and is further validated through\ncomparison with discrete dislocation dynamical simulation results. Based on the\nfindings in this article and in our previous works, a general strategy for\nincorporating short-range dislocation correlations in continuum models of\ndislocations is proposed."
    },
    {
        "anchor": "Switchable enhanced spin photocurrent in Rashba and cubic Dresselhaus\n  ferroelectric semiconductors: Generating and controlling spin current (SC) are of central interest in spin\nphysics and applications. To date, the spin-orbit interaction (SOI) is an\nestablished pathway to generate SC through the spin-charge current conversion.\nWe predict an efficient spin-light conversion via the Rashba and higher-order\ncubic Dresselhaus SOIs in ferroelectrics. Different from the known Edelstein\neffect, where SC is created by the nonequilibrium spin density, our predicted\nspin-polarized current is from direct interactions between light and unique\nspin textures generated by SOI in ferroelectrics. Using first-principles\nsimulations, we demonstrate these concepts by calculating the DC spin\nphotocurrent in a prototypical Rashba ferroelectric, {\\alpha}-GeTe. The\nphoto-induced SC is about two orders of magnitude larger than the charge\nphotocurrent. More importantly, we can conveniently switch the direction of SC\nby an applied electric field via inverting the spin textures. These predictions\ngive hope to generating and controlling light-driven SC via nonvolatile\nelectric-field.",
        "positive": "The influence of Auger recombination on the performance of quantum-dot\n  light-emitting diodes: A growing interest in colloidal quantum dot (QD) based light-emitting diodes\n(QD-LEDs) has been motivated by the exceptional color purity and spectral\ntunability of QD emission as well as the amenability of QD materials to highly\nscalable and inexpensive solution processing. One current challenge in the\nQD-LED field has been a still incomplete understanding of the role of extrinsic\nfactors (e.g., recombination via QD surface defects) versus intrinsic processes\nsuch as multicarrier Auger recombination or electron-hole separation due to\napplied electric field in defining device efficiency. Here, we address this\nproblem with a study of excited-state dynamics in a series of structurally\nengineered QDs, which is performed in parallel with characterization of their\nperformance upon incorporation into LEDs. The results of this study indicate\nthat under both zero and forward bias, a significant fraction of the QDs within\nthe active emitting layer is negatively charged and therefore, Auger\nrecombination represents an important factor limiting the efficiency of these\ndevices. We further observe that the onset of the LED efficiency roll-off is\nalso controlled by Auger recombination and can be shifted to higher currents by\nusing newly developed QDs with an intermediate alloy layer at the core-shell\ninterface introduced for suppression of Auger decay. Our findings suggest that\nfurther improvement in the performance of QD-LEDs can be achieved by developing\neffective approaches for controlling Auger recombination and/or minimizing the\neffects of QD charging via improved balancing of electron and hole injection\ncurrents."
    },
    {
        "anchor": "Rapid Thermal Annealing for Surface Optimisation of ZnO Substrates for\n  MBE-Grown Oxide Two-Dimensional Electron Gases: Two-dimensional electron gases (2DEGs) at the ZnO/ZnMgO interface are\npromising for applications in spintronics and quantum computing due to the\ncombination of low spin-orbit coupling and high electron mobility. Growing high\nmobility 2DEGs requires high quality substrates with low impurity densities. In\nthis work we demonstrate a ZnO substrate sample treatment combining high\ntemperature rapid thermal annealing and chemical etching to improve the surface\nquality for the subsequent growth of 2DEGs. This process enables the growth of\na 2DEG with low-temperature mobility of $4.8\\times10^4$~cm$^2$V$^{-1}$s$^{-1}$.\nAn unannealed control sample shows a scattering rate at least three times\ngreater than the annealed sample.",
        "positive": "Extended characterization methods for covalent functionalization of\n  graphene on copper: Graphene is a material of great potential in a broad range of applications,\nfor each of which specific tuning of the materials properties is required. This\ncan be achieved, for example, by covalent functionalization. We have exploited\ntwo protocols for surface grafting, either by diazonium salts or by\nnucleophilic exchange, to perform graphene covalent modification directly on a\ncopper substrate, which is routinely used for the synthesis of the material,\nand investigated the difference in reactivity compared with other substrates.\nThe successful functionalization was confirmed by Raman and surface-enhanced\nRaman spectroscopy, mass spectrometry, X-ray photoelectron spectroscopy and\nscanning electron microscopy with energy-dispersive X-ray spectroscopy. In\naddition, we have found that the copper substrate can serve as a plasmonic\nsurface enhancing the Raman spectra. Furthermore, the covalent grafting was\nshown to tolerate the transfer process, thus allowing ex post transfer from\ncopper to other substrates. This protocol avoids wet processing and enables an\nall-gas-phase transformation of functionalized graphene, which eliminates the\nmain sources of contamination."
    },
    {
        "anchor": "Observation of ripples under different angles: The off-normal ion irradiation of semiconductor materials is seen to induce\nnanopatterning effects. Different theories are proposed to explain the\nmechanisms that drive self-reorganization of amorphisable surfaces. One of the\nprominent hypothesis associates formation of nanopatterning with the changes of\nsputtering characteristics caused by changes in surface morphology. At\nultra-low energy, when sputtering is negligible, the Si surface has still been\nseen to re-organize forming surface ripples with the wave vector either aligned\nwith the ion beam direction or perpendicular to it.In this work, we investigate\nthe formation of ripples using molecular dynamics in all the three regimes of\nripple formation: low angles where no ripples form, intermediate regime where\nthe ripple wave vectors are parallel to the beam, and high angles where they\nare perpendicular to it. We obtain atom-level insight on how the ion-beam\ndriven atomic dynamics at the surface contributes to organization, or lack of\nit, in all the different regimes. Results of our simulations agree well with\nexperimental observations in the same range of ultra-low energy of ion\nirradiation.",
        "positive": "Monovacancy and Substitutional Defects in Hexagonal Silicon Nanotubes: We present a first-principle study of geometrical and electronic structure of\nhexagonal single-walled silicon nanotubes with a monovacancy or a\nsubstitutional defect. The C, Al or P atoms are chosen as substitutional\nimpurities. It is found that the defect such as a monovacancy or a\nsubstitutional impurity results in deformation of the hexagonal single-walled\nsilicon nanotube. In both cases, a relatively localized unoccupied state near\nthe Fermi level occurs due to this local deformation. The difference in\ngeometrical and electronic properties of different substitutional impurities is\ndiscussed."
    },
    {
        "anchor": "Electric field effects, Mott insulator, Surface patterning, Scanning\n  tunneling microscopy, Transition metal chalcogenides: We report the first experimental evidence for a strong electromechanical\ncoupling in the Mott insulator GaTa4Se8 allowing a highly reproducible\nnano-writing with a Scanning Tunneling Microscope (STM). The local electric\nfield across the STM junction is observed to have a threshold value above which\nthe clean (100) surface of GaTa4Se8 becomes mechanically instable: At voltage\nbiases V > 1.1V the surface suddenly inflates and comes in contact with the STM\ntip, resulting in nanometer size craters. The formed pattern can be\nindestructibly \"read\" by STM at lower voltage bias, thus allowing a 5\nTdots/inch2 dense writing/reading at room temperature. The discovery of the\nelectromechanical coupling in GaTa4Se8 might give new clues in the\nunderstanding of the Electric Pulse Induced Resistive Switching recently\nobserved in this stoechiometric Mott insulator.",
        "positive": "Parametric Design of Minimal Mass Tensegrity Bridges Under Yielding and\n  Buckling Constraints: This paper investigates the use of the most fundamental elements; cables for\ntension and bars for compression, in the search for the most efficient bridges.\nStable arrangements of these elements are called tensegrity structures. We show\nherein the minimal mass arrangement of these basic elements to satisfy both\nyielding and buckling constraints. We show that the minimal mass solution for a\nsimply-supported bridge subject to buckling constraints matches Michell's 1904\npaper which treats the case of only yield constraints, even though our boundary\nconditions differ. The necessary and sufficient condition is given for the\nminimal mass bridge to lie totally above (or below) deck. Furthermore this\ncondition depends only on material properties. If one ignores joint mass, and\nconsiders only bridges above deck level, the optimal complexity (number of\nelements in the bridge) tends toward infinity (producing a material continuum).\nIf joint mass is considered then the optimal complexity is finite. The optimal\n(minimal mass) bridge below deck has the smallest possible complexity (and\ntherefore cheaper to build), and under reasonable material choices, yields the\nsmallest mass bridge."
    },
    {
        "anchor": "Lattice constants and magnetism of L10-ordered FePt under high pressure: We studied the relationship between the lattice constant and magnetism of\nL10-ordered FePt under high pressure by means of first-principles calculations\nand synchrotron x-ray measurements. Based on our calculations, we found that\nthe c/a ratio shows an anomaly at ~ 20 GPa and that the Pt magnetic moment is\nsharply suppressed at ~ 60 GPa. As for the c/a, we experimentally verified the\nanomaly at ~ 20 GPa by powder x-ray diffraction. We also measured the x-ray\nmagnetic circular dichroism at the Pt L edge up to ~ 20 GPa. Any significant\nchange of the Pt magnetic moment was not observed, in agreement with the\ncalculations. These results thus indicate the possibility that novel magnetic\nstates can be created in L10-ordered FePt by lattice deformation under high\npressure.",
        "positive": "Dimer Crystallization Induced by Elemental Substitution in the Honeycomb\n  Lattice of Ru1-xOsxCl3: Substitution effects of Os for Ru in {\\alpha}-RuCl3 are investigated in a\nwide composition range of 0 =< x =< 0.67 in Ru1-xOsxCl3 by X-ray and electron\ndiffraction, magnetic susceptibility, heat capacity, and Raman spectroscopy\nmeasurements. Apart from the Kitaev physics with antiferromagnetic interactions\nincreasing with x, a rich phase diagram is obtained, which includes an\nantiferromagnetic long-range order below 12 K for x =< 0.15, a dome-shaped\nspin-singlet dimer phase below 130 K for 0.15 =< x =< 0.40, and a magnetic\nshort-range order for x > 0.40. A dimerization as similarly observed in\n{\\alpha}-RuCl3 under high pressure occurs in the spin-singlet phase. It is\nsuggested that Ru-Os pairs in the solid solutions tend to form dimers with\nshort bonds and trigger the first-order transition in the presence of\npseudo-threefold rotational symmetry for dimerization around a substituted Os\natom only at low substitutions. This is a rare example of molecular orbital\ncrystallization induced by elemental substitution in a highly disordered\nsystem. The short-range order at high substitutions may be related to a\nrandom-singlet state stabilized by bond disorder in the honeycomb net."
    },
    {
        "anchor": "Chemically-Mediated quantum criticality in NbFe_2: Laves-phase Nb{1+c}Fe_{2-c} is a rare itinerant intermetallic compound\nexhibiting magnetic quantum criticality at c_{cr}=1.5%Nb excess; its origin,\nand how alloying mediates it, remains an enigma. For NbFe_2, we show that an\nunconventional band critical point (uBCP) above the Fermi level E_F explains\nmost observations, and that chemical alloying mediates access to this uBCP by\nan increase in E_F with decreasing electrons (increasing %Nb), counter to\nrigid-band concepts. We calculate that E_F enters the uBCP region for c_{cr} >\n1.5%Nb and by 1.74%Nb there is no Nb site-occupation preference between\nsymmetry-distinct Fe sites, i.e., no electron-hopping disorder, making\nresistivity near constant as observed. At larger Nb (Fe) excess, the\nferromagnetic Stoner criterion is satisfied.",
        "positive": "Structural relaxation affecting shear transformation avalanches in\n  metallic glasses: Avalanche behaviors, characterized by power-law statistics and structural\nrelaxation that induces shear localization in amorphous plasticity, play an\nessential role in deciding the mechanical properties of amorphous metallic\nsolids (i.e., metallic glasses). However, their interdependence is still not\nfully understood. To investigate the influence of structural relaxation on\nelementary avalanche behavior, we perform molecular-dynamics simulations for\nthe shear deformation test of metallic glasses using two typical metallic-glass\nmodels comprising a less-relaxed (as-quenched) glass and a well-relaxed\n(well-aged) glass exhibiting a relatively homogeneous deformation and a\nshear-band-like heterogeneous deformation, respectively. The data on elementary\navalanches obtained from both glass models follow the same power-law statistics\nwith different maximum event sizes, and the well-relaxed glass shows shear\nlocalization. Evaluating the spatial correlation functions of the nonaffine\nsquared displacements of atoms during each elementary avalanche event, we\nobserve that the shapes of the elementary avalanche regions in the well-relaxed\nglasses tend to be anisotropic, whereas those in the less-relaxed glasses are\nrelatively isotropic. Furthermore, we demonstrate that a temporal clustering in\nthe direction of the avalanche propagation emerges, and a considerable\ncorrelation between the anisotropy and avalanche size exists in the\nwell-relaxed glass model."
    },
    {
        "anchor": "All-electrical operation of a Curie-switch at room temperature: We present all-electrical operation of a Fe$_x$Cr$_{1-x}$-based Curie switch\nat room temperature. More specifically, we study the current-induced\nthermally-driven transition from ferromagnetic to antiferromagnetic\nRuderman-Kittel-Kasuya-Yosida (RKKY) indirect coupling in a\nFe/Cr/Fe$_{17.5}$Cr$_{82.5}$/Cr/Fe multilayer. Magnetometry measurements at\ndifferent temperatures show that the transition from the ferromagnetic to the\nantiferromagnetic coupling at zero field is observed at $\\sim$325K. Analytical\nmodelling confirms that the observed temperature-dependent transition from\nindirect ferromagnetic to indirect antiferromangetic interlayer exchange\ncoupling originates from the modification of the effective interlayer exchange\nconstant through the ferromagnetic-to-paramagnetic transition in the\nFe$_{17.5}$Cr$_{82.5}$ spacer with minor contributions from the\nthermally-driven variations of the magnetization and magnetic anisotropy of the\nFe layers. Room-temperature current-in-plane magnetotransport measurements on\nthe patterned Fe/Cr/Fe$_{17.5}$Cr$_{82.5}$/Cr/Fe strips show the transition\nfrom the 'low-resistance' parallel to the 'high-resistance' antiparallel\nremanent magnetization configuration, upon increased probing current density.\nQuantitative comparison of the switching fields, obtained by magnetometry and\nmagnetotransport, confirms that the Joule heating is the main mechanism\nresponsible for the observed current-induced resistive switching.",
        "positive": "Computational study of the effective three-ion interaction potentials in\n  liquid metals with high density of electron gas: Based on the many-body theory of metals in the third order of the\nperturbation expansion in electron-ion interaction pseudopotential, the\npotentials of pair and three-ion interactions are calculated in liquid lead,\naluminium and beryllium at their melting temperatures. The reducible and\nirreducible three-ion interactions have an attractive nature on distances\napproximately equal to an average distance between ions in metals. It results\nin the shortening of average interatomic distance in an equilibrium state of\nmetal. The potential landscapes created by a pair of fixed ions relative to the\nthird ion are constructed. It is shown that with increasing of an electronic\ndensity the contribution as reducible, that and irreducible three-ion\ninteraction is increased. It is shown also that the influence of reducible\nthree-ion interaction on a potential landscape in a cluster of three ions is\nconsiderably larger than influence of irreducible three-ion interaction."
    },
    {
        "anchor": "Island nucleation in thin-film epitaxy: A first-principles investigation: We describe a theoretical study of the role of adsorbate interactions in\nisland nucleation and growth, using Ag/Pt(111) heteroepitaxy as an example.\n  From density-functional theory, we obtain the substrate-mediated Ag adatom\npair interaction and we find that, past the short range, a repulsive ring is\nformed about the adatoms. The magnitude of the repulsion is comparable to the\ndiffusion barrier. In kinetic Monte Carlo simulations, we find that the\nrepulsive interactions lead to island densities over an order of magnitude\nlarger than those predicted by nucleation theory and thus identify a severe\nlimitation of its applicability.",
        "positive": "Electronic properties of graphene nano-flakes: Energy gap, permanent\n  dipole, termination effect and Raman spectroscopy: The electronic properties of graphene nano-flakes (GNFs) with different edge\npassivation is investigated by using density functional theory. Passivation\nwith F and H atoms are considered: C$_{N_c}$ X$_{N_x}$ (X=F or H). We studied\nGNFs with $10<N_c<56$ and limit ourselves to the lowest energy configurations.\nWe found that: i) the energy difference $\\Delta$ between the highest occupied\nmolecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO)\ndecreases with $N_c$, ii) topological defects (pentagon and heptagon) break the\nsymmetry of the GNFs and enhance the electric polarization, iii) the mutual\ninteraction of bilayer GNFs can be understood by dipole-dipole interaction\nwhich were found sensitive to the relative orientation of the GNFs, iv) the\npermanent dipoles depend on the edge terminated atom, while the energy gap is\nindependent of it, and v) the presence of heptagon and pentagon defects in the\nGNFs results in the largest difference between the energy of the spin-up and\nspin-down electrons which is larger for the H-passivated GNFs as compared to\nF-passivated GNFs. Our study shows clearly the effect of geometry, size,\ntermination and bilayer on the electronic properties of small GNFs.This study\nreveals important features of graphene nano-flakes which can be detected using\nRaman spectroscopy."
    },
    {
        "anchor": "Origin of the efficient light emission from inversion domain boundaries\n  in GaN: Intentionally-produced inversion domain boundaries in GaN have been reported\nto be highly efficient recombination centers. Here I report a rationale for\nthis phenomenon based on ab initio density-functional calculations. I also\npropose a model, based on the existence of polarization in GaN, of the\nobservation that a domain boundary acts as a rectifying junction under voltage\napplied between the two opposite-polarity surfaces.",
        "positive": "Topological Electride Phase of Sodium at High Pressures and Temperatures: Ab initio evolutionary structure searches coupled with quasiharmonic\ncalculations predict that the insulating Na hP4 phase transitions to a novel\nP63/m phase between 200 GPa at 150 K, and 350 GPa at 1900 K. P63/m Na is a\ntopological semimetal with a Dirac nodal surface that is protected by a\nnon-symmorphic symmetry, S2z . It is characterized by localized non-nuclear\ncharge within 1D honeycomb channels and 0D cages rendering it an electride.\nThese results highlight the complexity of warm dense sodiums electronic\nstructure and free energy landscape that emerges at conditions where ionic\ncores overlap."
    },
    {
        "anchor": "Formation of Stoichiometric CsF$_n$ Compounds: Alkali halides $MX$, have been viewed as typical ionic compounds,\ncharacterized by 1:1 ratio necessary for charge balance between M$^+$ and\nX$^-$. It was proposed that group I elements like Cs can be oxidized further\nunder high pressure. Here we perform a comprehensive study for the CsF-F system\nat pressures up to 100 GPa, and find extremely versatile chemistry. A series of\nCsF$_n$ ($n$ $\\geq$ 1) compounds are predicted to be stable already at ambient\npressure. Under pressure, 5$p$ electrons in Cs atoms become active, with\ngrowing tendency to form Cs$^{3+}$ and Cs$^{5+}$ valence states at\nfluorine-rich conditions. Although Cs$^{2+}$ and Cs$^{4+}$ are not\nenergetically favoured, the interplay between two mechanisms (polyfluoride\nanions and polyvalent Cs cations) allows CsF$_2$ and CsF$_4$ compounds to be\nstable under pressure. The estimated defluorination temperatures of CsF$_n$\n(n=2,3,5) compounds at atmospheric pressure (218 $^\\circ$C, 150 $^\\circ$C, -15\n$^\\circ$C, respectively), are attractive for fluorine storage applications.",
        "positive": "Exact exchange-correlation potentials for calculating the fundamental\n  gap with a fixed number of electrons: Capturing the discontinuous shift by $\\Delta$ in the exact\nexchange-correlation (xc) potential is the standard proposal for calculating\nthe fundamental gap, $E_\\mathrm{g}$, from the Kohn-Sham (KS) gap,\n$\\varepsilon_\\mathrm{g}$, within KS density functional theory (DFT), as\n$E_\\mathrm{g} = \\varepsilon_\\mathrm{g} + \\Delta$, yet this discontinuity is\nabsent from existing approximations. The '$N$-centered' formulation of ensemble\nDFT artificially maintains a total electron number, $N$, in order to yield\n$E_\\mathrm{g}$ not through a discontinuous shift in the xc potential but via\nthe ensemble-weight derivative of the xc energy. Within the $N$-centered\napproach we calculate exact xc potentials for a one-dimensional finite system\nand show analytically that $\\Delta$ can in fact be interpreted as a\ndiscontinuous shift in the exact $N$-centered ensemble xc potential, thereby\nextending to charged excitations an exact property of uncharged excitations. We\nshow that applying the Levy-Zahariev 'shift-in-potential' procedure in this\ncontext relocates the discontinuous shift to the unimportant periphery of the\nsystem, so that the exact xc potential in effect is free of discontinuities and\nthus the inability of a local functional to capture discontinuous behavior is\ninconsequential."
    },
    {
        "anchor": "Local Charged States in La_{0.89}Sr_{0.11}MnO_3 Single Crystals: We report the direct evidence of the possibility of charge segregation in\nmanganites. The high contrast of electric-field-induced local charged states is\nobserved during more than 100 hours at room temperature. These induced states\ndisplay a piezoelectric response and polar properties. This effect may be an\nexample of a new kind of polar ordering in solid state.",
        "positive": "Enantioselective adsorption on magnetic surfaces: From the beginning of molecular theory, the interplay of chirality and\nmagnetism has intrigued scientists. There is still the question if\nenantiospecific adsorption of chiral molecules occurs on magnetic surfaces.\nEnantiomer discrimination was conjectured to arise from chirality-induced spin\nseparation within the molecules and exchange interaction with the substrate's\nmagnetization. Here we show that single helical aromatic hydrocarbons undergo\nenantioselective adsorption on ferromagnetic cobalt surfaces. Spin and\nchirality sensitive scanning tunneling microscopy reveals that molecules of\nopposite handedness prefer adsorption onto cobalt islands with opposite\nout-of-plane magnetization. As mobility ceases in the final chemisorbed state,\nit is concluded that enantioselection must occur in a physisorbed transient\nprecursor state. State-of-the-art spin-resolved ab initio simulations support\nthis scenario by refuting enantio-dependent chemisorption energies. These\nfindings demonstrate that van der Waals interaction should also include\nspin-fluctuations which are crucial for molecular magnetochiral processes."
    },
    {
        "anchor": "Revealing Grain Boundaries and Defect Formation in Nanocrystal\n  Superlattices by Nanodiffraction: X-ray nanodiffraction is applied to study the formation and correlation of\ndomain boundaries in mesocrystalline superlattices of PbS nanocrystals with\nface-centered cubic structure. Each domain of the superlattice can be described\nwith one of two mesocrystalline polymorphs with different orientational order.\nClose to a grain boundary, the lattice constant decreases and the superlattice\nundergoes an out-of-plane rotation, while the orientation of the nanocrystals\nwith respect to the superlattice remains unchanged. These findings are\nexplained with the release of stress on the expense of specific\nnanocrystal-substrate interactions. The fact that correlations between adjacent\nnanocrystals are found to survive the structural changes at most grain\nboundaries implies that the key to nanocrystal superlattices with macroscopic\ndomain sizes are strengthened interactions with the substrate.",
        "positive": "One-Pot Multi-component Synthesis of 1,4-Dihydropyridine Derivatives in\n  Biocompatible Deep Eutectic Solvents: An efficient protocol for the synthesis of differently substituted 1,\n4-dihydropyridines in deep eutectic solvents under solvent-free conditions is\nreported herewith. Excellent yields of the resultant products have been\nobtained. Recyclability studies have also been performed for deep eutectic\nsolvents with very little loss in activity up to five recycles."
    },
    {
        "anchor": "Evidence of Weyl Fermion Enhanced Thermal Conductivity Under Magnetic\n  Fields in Antiferromagnetic Topological Insulator Mn(Bi(1-x)Sb(x))2Te4: We report thermal conductivity and Seebeck effect measurements on\nMn(Bi1-xSbx)2Te4 (MBST) with x = 0.26 under applied magnetic fields below 50 K.\nOur data shows clear indications of the electronic structure transition induced\nby the antiferromagnetic (AFM) to ferromagnetic (FM) transition driven by\napplied magnetic field as well as significant positive magnetothermal\nconductivity in the Weyl semimetal state of MBST. Further, by examining the\ndependence of magnetothermal conductivity on field orientation for MBST and\ncomparison with the magnetothermal conductivity of MnBi2Te4 we see evidence of\na contribution to thermal conductivity due to Weyl fermions in the FM phase of\nMBST. From the temperature dependence of Seebeck coefficient under magnetic\nfields for MBST, we also observed features consistent with the Fermi surface\nevolution from a hole pocket in the paramagnetic state to a Fermi surface with\ncoexistence of electron and hole pockets in the FM state. These findings\nprovide further evidence for the field-driven topological phase transition from\nan AFM topological insulator to a FM Weyl semimetal.",
        "positive": "Millimeter-Wave Spectroscopy of the Organic spin-Peierls System\n  b'-(ET)2SF5CF2SO3: The first purely organic BEDT-TTF spin-Peierls system, b'-(ET)2SF5CF2SO3, has\nbeen confirmed using a high-frequency electron spin resonance (EPR) cavity\nperturbation technique. The material exhibits the characteristics of a\nquasi-one-dimensional (1D) Heisenberg antiferromagnetic spin system above 30 K,\nbut undergoes a second-order transition, at TSP = 33 K, to a singlet ground\nstate, due to a progressive spin-lattice dimerization. The spin-Peierls state\nis evidenced by a sharp drop in the spin susceptibility below 24 K for the\nmagnetic field parallel to each of the three principle axes (i.e. H7a, H7b, and\nH7c). The 1D chain axis has been identified as the crystallographic b axis from\nthe g value analysis. The singlet-triplet gap, Ds(0) = 114 (+-21)K, was\ndetermined using a modified BCS theory. Also, we describe in some detail the\nmillimeter-wave vector network analyzer (MVNA) for researchers who have\ninterest in precision EPR measurements at higher magnetic fields and\nfrequencies."
    },
    {
        "anchor": "Features of low-to-high cycle fatigue fracture transition: It was experimentally confirmed that if steel cyclic stress reduces to less\nthan tensile yield stress values, i.e. in case of high-cycle fatigue, the\nmechanism of fracture changes from dislocation to vacancy one. This conclusion\nwas based on the fact that steel density determined by the method of liquid\ndisplacement is less than that of steel in both initial condition and after\nfracture under the cyclic loads exceeding tensile yield stress values. In the\nlatter case steel hardness increases, whereas the steels fractured under the\ncyclic stresses less than their tensile yield stress values show no change in\nhardness. It means that in such a case metal fractures without strain\nhardening, i.e. undergoes brittle fracturing developing by vacancy mechanism\nrather than by dislocation one. As a result such steel obtains the structure\nand properties similar to those appearing after its exposure to radiation, i.e.\nfriability and brittleness. The results obtained allow us to explain the\npresence of a horizontal section in the W\\\"ohler fatigue failure diagram",
        "positive": "Decomposition mechanism and the effects of metal additives on the\n  kinetics of lithium alanate: First-principles density functional theory studies have been carried out for\nnative defects and transition-metal (Ti and Ni) impurities in lithium alanate\n(LiAlH$_{4}$), a potential material for hydrogen storage. On the basis of our\ndetailed analysis of the structure, energetics, and migration of lithium-,\naluminum-, and hydrogen-related defects, we propose a specific atomistic\nmechanism for the decomposition and dehydrogenation of LiAlH$_{4}$ that\ninvolves mass transport mediated by native point defects. We also discuss how\nTi and Ni impurities alter the Fermi-level position with respect to that in the\nundoped material, thus changing the concentration of charged defects that are\nresponsible for mass transport. This mechanism provides an explanation for the\nexperimentally observed lowering of the temperature for the onset of\ndecomposition and of the activation energy for hydrogen desorption from\nLiAlH$_{4}$."
    },
    {
        "anchor": "Orbital degrees of freedom as origin of magnetoelectric coupling in\n  magnetite: A microscopic understanding of magnetoelectricity, i.e. the coupling between\nmagnetic (electric) properties and external electric (magnetic) fields, is a\ncrucial milestone for future generations of electrically-controlled spintronic\ndevices. Here, we focus on the first magnetoelectric known to mankind:\nmagnetite. By means of a joint approach based on phenomenological Landau theory\nand density-functional simulations, we show that magnetoelectricity in\ncharge-/orbital-ordered Fe3O4 in the non-centrosymmetric Cc structure is driven\nby the interplay between a peculiar orbital-order and on-site spin-orbit\ncoupling. The excellent agreement with available experiments confirms our\ntheoretical picture, pointing to magnetite as a prototype of a novel category\nof magnetoelectrics where ferroelectric polarization can be induced, tuned or\nswitched via a magnetic field.",
        "positive": "Twin nucleation in Ti: A study using nudged elastic band (NEB) method: Capturing twin nucleation in full-field crystal plasticity is a long-standing\nproblem in materials science. The challenge resides mainly in the biased\nregional lattice transformation associated with twin formation in defiance of\nits obedience to a threshold stress law which could be fulfilled in regions\nwhere twinning is deferred. Hence, determining a favorable site for nucleation\nof a twin variant remains a daunting task. We hypothesized that this\nsite-specific nucleation is sensitive to the prior atomic structure of the\nlattice so twin embryos form in regions where the lattice transformation energy\nis minimum. Thus, quantifying the local strain energy required to trigger a\nstable twin underscores the non-pseudo-slip behavior of twin nucleation and\ngrowth. We performed atomistic calculations based on the nudged elastic band\nmethod to identify the minimum energy path and activation energy associated\nwith {10-12} twin nucleation in titanium. Results of calculations demonstrate\nthat the role of stress and atomic structure in twin nucleation could be\nunderstood in terms of the minimum energy path, energy barrier, and relaxed\nenergy. Remarkably, for symmetric tilt grain boundaries, a linear correlation\nbetween the nucleation stress and grain boundary energy was observed."
    },
    {
        "anchor": "Precise measurements of electron and hole g-factors of single quantum\n  dots by using nuclear field: We demonstrated the cancellation of the external magnetic field by the\nnuclear field at one edge of the nuclear polarization bistability in single\nInAlAs quantum dots. The cancellation for the electron Zeeman splitting gives\nthe precise value of the hole g-factor. By combining with the exciton g-factor\nthat is obtained from the Zeeman splitting for linearly polarized excitation,\nthe magnitude and sign of the electron and hole g-factors in the growth\ndirection are evaluated.",
        "positive": "Effects of Hexagonal Boron Nitride Encapsulation on the Electronic\n  Structure of Few-layer MoS$_2$: The hexagonal boron nitride (hBN) encapsulation has been widely used in the\nelectronics applications of 2D materials to improve device performance by\nprotecting 2D materials against contamination and degradation. It is often\nassumed that hBN layers as a dielectric would not affect the electronic\nstructure of encapsulated 2D materials. Here we studied few-layer MoS$_2$\nencapsulated in hBN flakes by using a combination of theoretical and\nexperimental Raman spectroscopy. We found that after the encapsulation the\nout-of-plane A$_{1g}$ mode is upshifted, while the in-plane E$_{2g}^1$ mode is\ndownshifted. The measured downshift of the E$_{2g}^1$ mode does not decrease\nwith increasing the thickness of MoS$_2$, which can be attributed to tensile\nstrains in bilayer and trilayer MoS$_2$ caused by the typical experimental\nprocess of the hBN encapsulation. We estimated the strain magnitude and found\nthat the induced strain may cause the K-Q crossover in the conduction band of\nfew-layer MoS$_2$, so greatly modifies its electronic properties as an n-type\nsemiconductor. Our study suggests that the hBN encapsulation should be used\nwith caution, as it may affect the electronic properties of encapsulated\nfew-layer 2D materials."
    },
    {
        "anchor": "Interplay Between Mixed and Pure Exciton States Controls Singlet Fission\n  in Rubrene Single Crystals: Singlet fission (SF) is a multielectron process in which one singlet exciton\nS converts into a pair of triplet excitons T+T. SF is widely studied as it may\nhelp overcome the Shockley-Queisser efficiency limit for semiconductor\nphotovoltaic cells. To elucidate and control the SF mechanism, great attention\nhas been given to the identification of intermediate states in SF materials,\nwhich often appear elusive due to the complexity and fast timescales of the SF\nprocess. Here, we apply 10fs-1ms transient absorption techniques to high-purity\nrubrene single crystals to disentangle the intrinsic fission dynamics from the\neffects of defects and grain boundaries and to identify reliably the fission\nintermediates. We show that above-gap excitation directly generates a hybrid\nvibronically assisted mixture of singlet state and triplet-pair multiexciton\n[S:TT], which rapidly (<100fs) and coherently branches into pure singlet or\ntriplet excitations. The relaxation of [S:TT] to S is followed by a relatively\nslow and temperature-activated (48 meV activation energy) incoherent fission\nprocess. The SF competing pathways and intermediates revealed here unify the\nobservations and models presented in previous studies of SF in rubrene and\npropose alternative strategies for the development of SF-enhanced photovoltaic\nmaterials.",
        "positive": "Multi-scale modelling of supercapacitors: From molecular simulations to\n  a transmission line model: We perform molecular dynamics simulations of a typical nanoporous-carbon\nbased supercapacitors. The organic electrolyte consists in\n1-ethyl-3-methyl--imidazolium and hexafluorophosphate ions dissolved in\nacetonitrile. We simulate systems at equilibrium, for various applied voltages.\nThis allows us to determine the relevant thermodynamic (capacitance) and\ntransport (in-pore resistivities) properties. These quantities are then\ninjected in a transmission line model for testing its ability to predict the\ncharging properties of the device. The results from this macroscopic model are\nin good agreement with non-equilibrium molecular dynamics simulations, which\nvalidates its use for interpreting electrochemical impedance experiments."
    },
    {
        "anchor": "Electrostatic gating of metallic and insulating phases in SmNiO3\n  ultrathin films: The correlated electron system SmNiO3 exhibits a metal-insulator phase\ntransition at 130 {\\deg}C. Using an ionic liquid as an electric double layer\n(EDL) gate on three-terminal ultrathin SmNiO3 devices, we investigate gate\ncontrol of the channel resistance and transition temperature. Resistance\nreduction is observed across both insulating and metallic phases with ~25%\nmodulation at room temperature. We show that resistance modulation is\npredominantly due to electrostatic charge accumulation and not electrochemical\ndoping by control experiments in inert and air en-vironments. We model the\nresistance behavior and estimate the accumulated sheet density (~1-2 x 10^14\ncm^-2) and EDL capacitance (~12 {\\mu}F/cm^2).",
        "positive": "Two Dimensional Ferromagnetic Semiconductor: Monolayer CrGeS$_3$: Recently, two-dimensional ferromagnetic semiconductors have been an important\nclass of materials for many potential applications in spintronic devices. Based\non density functional theory, we systematically explore the magnetic and\nelectronic properties of CrGeS$_3$ with the monolayer structures. The\ncomparison of total energy between different magnetic states ensures the\nferromagnetic ground state of monolayer CrGeS$_3$. It is also shown that\nferromagnetic and semiconducting properties are exhibited in monolayer\nCrGeS$_3$ with the magnetic moment of 3 $\\mu_{B}$ for each Cr atom, donated\nmainly by the intense $dp$$\\sigma$-hybridization of Cr $e_g$-S $p$. There are\nthe bandgap of 0.70 eV of spin-up state in the monolayer structure when 0.77 eV\nin spin-down state. The global gap is 0.34 eV (2.21 eV by using HSE06\nfunctional), which originates from bonding $dp\\sigma$ hybridized states of Cr\n$e_g$-S $p$ and unoccupied Cr $t_{2g}$-Ge $p$ hybridization. Besides, we\nestimate that the monolayer CrGeS$_3$ possesses the Curie temperature of 161 K\nby mean-field theory."
    },
    {
        "anchor": "Vibrations of Periodically Poled Lithium Niobate Bar with 0.3-mm Long\n  Domains: The three dimensional vibrations in a periodically poled ZX-cut Lithium\nNiobate thin bar with 0.3-mm long domains are considered. The acoustical\nvibrations may be excited by the 1) longitudinal acousto-electric current when\na radio frequency voltage is parallel to the x-axis, and 2) transverse electric\nfield when a radio frequency voltage is parallel to the z-axis. The\ncomputations by the Final Element Method reveal all the three displacements\nalong the x, y, and z crystallographic axes. The amplitudes may be different\nfor two types of vibration excitations. The positions of peaks in admittance\nversus frequency correlate with the frequencies of maximum acoustic amplitudes.\nThe superlattice with 0.3-mm long domains along the x-axis is fabricated in the\nz-cut 0.5-mm-thick wafer. The experimental data on the radio frequency\nadmittance versus frequency is in agreement with the corresponding theoretical\ncomputations.",
        "positive": "First-principles data for solid-solution strengthening of magnesium:\n  From geometry and chemistry to properties: Solid-solution strengthening results from solutes impeding the glide of\ndislocations. Existing theories of strength rely on solute-dislocation\ninteractions, but do not consider dislocation core structures, which need an\naccurate treatment of chemical bonding. Here, we focus on strengthening of Mg,\nthe lightest of all structural metals and a promising replacement for heavier\nsteel and aluminum alloys. Elasticity theory, which is commonly used to predict\nthe requisite solute-dislocation interaction energetics, is replaced with\nquantum-mechanical first-principles calculations to construct a predictive\nmesoscale model for solute strengthening of Mg. Results for 29 different\nsolutes are displayed in a \"strengthening design map\" as a function of solute\nmisfits that quantify volumetric strain and slip effects. Our strengthening\nmodel is validated with available experimental data for several solutes,\nincluding Al and Zn, the two most common solutes in Mg. These new results\nhighlight the ability of quantum-mechanical first-principles calculations to\npredict complex material properties such as strength."
    },
    {
        "anchor": "Metastable rocksalt ZnO is $p$-type dopable: Despite decades of efforts, achieving $p$-type conductivity in the wide band\ngap ZnO in its ground-state wurtzite structure continues to be a challenge.\nHere we detail how $p$-type ZnO can be realized in the metastable,\nhigh-pressure rocksalt phase (also wide-gap) with Li as an external dopant.\nUsing modern first-principles defect theory, we predict Li to dope the rocksalt\nphase $p$-type by preferentially substituting for Zn and introducing shallow\nacceptor levels. Formation of compensating donors like interstitial Li and/or\nhydrogen, ubiqutous in the wurtzite phase, is inhibited by the close-packed\nnature of the rocksalt structure, which also exhibits relatively high absolute\nvalence band edge that promotes low hole effective mass and hole\ndelocalization. Resulting concentrations of free holes are predicted to exceed\n$\\sim10^{19}$ cm$^{-3}$ under O-rich synthesis conditions while under O-poor\nconditions the system remains $n$-type dopable. In addition to revealing\ncompelling opportunities offered by the metastable rocksalt structure in\nrealizing a long-sought $p$-type ZnO our results present polymorphism as a\npromising route to overcoming strong doping asymmetry of wide-band gap oxides.",
        "positive": "Driving ferromagnets into a critical region of a magnetic phase diagram: Exciting a ferromagnetic sample with an ultrashort laser pulse leads to a\nquenching of the magne- tization on a subpicosecond timescale. On the basis of\nthe equilibration of intensive thermodynamic variables we establish a powerful\nmodel to describe the demagnetization dynamics. We demonstrate that the\nmagnetization dynamics is mainly driven by the equilibration of chemical\npotentials. The minimum of magnetization is revealed as a transient electronic\nequilibrium state. Our method iden- tifies the slowing down of ultrafast\nmagnetization dynamics by a critical region within a magnetic phase diagram."
    },
    {
        "anchor": "Length scales and scale-free dynamics of dislocations in dense solid\n  solutions: The fundamental interactions between an edge dislocation and a random solid\nsolution are studied by analyzing dislocation line roughness profiles obtained\nfrom molecular dynamics simulations of Fe0.70Ni0.11 Cr0.19 over a range of\nstresses and temperatures. These roughness profiles reveal the hallmark\nfeatures of a depinning transition. Namely, below a temperature-dependent\ncritical stress, the dislocation line exhibits roughness in two different\nlength scale regimes which are divided by a so-called correlation length. This\ncorrelation length increases with applied stress and at the critical stress\n(depinning transition or yield stress) formally goes to infinity. Above the\ncritical stress, the line roughness profile converges to that of a random noise\nfield. Motivated by these results, a physical model is developed based on the\nnotion of coherent line bowing over all length scales below the correlation\nlength. Above the correlation length, the solute field prohibits such coherent\nline bow outs. Using this model, we identify potential gaps in existing\ntheories of solid solution strengthening and show that recent observations of\nlength-dependent dislocation mobilities can be rationalized.",
        "positive": "Ferromagnetic nodal-line metal in monolayer {\\em h}-InC: Based on first-principles calculations, we predict a new two-dimensional\nferromagnetic material that exhibits exotic Fermi surface topology. We show\nthat monolayer hexagonal indium carbide ({\\em h}-InC) is thermodynamically and\ndynamically stable, and it energetically favors the ferromagnetic ordering of\nspins. The perfectly planar geometry in two dimensions, together with\nferromagnetism, gives rise to a unique opportunity to encounter intriguing\nelectronic properties, captured in the Fermi surface and band topology. We show\nthat multiple nodal lines coexist in momentum space, accompanied by the\nelectron and hole pockets that touch each other linearly at the nodal lines.\nInclusion of spin-orbit coupling enriches the magnetic and electronic\nproperties of {\\em h}-InC. Spin-orbit coupling leads to an easy-plane type\nmagnetocrystalline anisotropy, and the nodal lines can be tuned into\ntopological nodal points, contingent upon the magnetization direction. Symmetry\nanalysis and a tight-binding model are provided to explain the nodal structure\nof the bands. Our findings suggest {\\em h}-InC as a new venue for supporting\ncarbon-based magnetism and exotic band topology in two dimensions."
    },
    {
        "anchor": "Dynamics of Einstein - de Haas Effect: Application to Magnetic\n  Cantilever: Local time-dependent theory of Einstein - de Haas effect is developed. We\nbegin with microscopicinteractions and derive dynamical equations that couple\nelastic deformations with internal twists due to spins. The theory is applied\nto the description of the motion of a magnetic cantilever caused by the\noscillation of the domain wall. Theoretical results are compared with a recent\nexperiment on Einstein - de Haas effect in a microcantilever.",
        "positive": "Persisting of Polar Distortion with Electron Doping in Lone-Pair Driven\n  Ferroelectrics: Free electrons can screen out long-range Coulomb interaction and destroy the\npolar distortion in some ferroelectric materials, whereas the coexistence of\npolar distortion and metallicity were found in several non-central-symmetric\nmetals (NCSMs). Therefore, the mechanisms and designing of NCSMs have attracted\ngreat interests. In this work, by first-principles calculation, we found the\npolar distortion in the lone-pair driven ferroelectric material PbTiO$_3$ can\nnot only persist, but also increase with electron doping. We further analyzed\nthe mechanisms of the persisting of the polar distortion. We found that the Ti\nsite polar instability is suppressed but the Pb site polar instability is\nintact with the electron doping. The Pb-site instability is due to the\nlone-pair mechanism which can be viewed as a pseudo-Jahn-Teller effect, a mix\nof the ground state and the excited state by ion displacement from the central\nsymmetric position. The lone-pair mechanism is not strongly affected by the\nelectron doping because neither the ground state or the excited state involved\nis at the Fermi energy. The enhancement of the polar distortion is related to\nthe increasing of the Ti ion size by doping. These results show the lone-pair\nstereoactive ions can be used in designing NCSMs."
    },
    {
        "anchor": "Direct Observation of Hydrogen Adsorption Sites and Nano-Cage Formation\n  in Metal-Organic Frameworks (MOF): The hydrogen adsorption sites in MOF5 were determined using neutron powder\ndiffraction along with first-principles calculations. The metal-oxide cluster\nis primarily responsible for the adsorption while the organic linker plays only\na secondary role. Equally important, at low temperatures and\nhigh-concentration, H2 molecules form unique interlinked high-symmetry\nnano-clusters with intermolecular distances as small as 3.0 Ang. and H2-uptake\nas high as 10-wt%. These results hold the key to optimizing MOF materials for\nhydrogen storage applications and also suggest that MOFs can be used as\ntemplates to create artificial interlinked hydrogen nano-cages with novel\nproperties.",
        "positive": "Comments regarding Transonic dislocation propagation in diamond by\n  Katagiri, et al. (Science 382, 69-72, 2023): We have carefully examined the above-referenced paper and find the claims of\nstacking fault formation and transonic dislocation propagation in diamond to be\nnot valid. Additionally, it is quite puzzling that 14 authors on this paper are\nalso co-authors on another recent paper that directly conflicts with the\ndislocation claims in the Science paper."
    },
    {
        "anchor": "Realizing robust large-gap quantum spin Hall state in 2D HgTe monolayer\n  on insulating substrate: Although many possible two-dimensional (2D) topological insulators (TIs) have\nbeen predicted in recent years, there is still lack of experimentally\nrealizable 2D TI. Through first-principles and tight-binding simulations, we\nfound an effective way to stabilize the robust quantum spin Hall state with a\nlarge nontrivial gap of 227 meV in 2D honeycomb HgTe monolayer by the\nAl$_2$O$_3$(0001) substrate. The band topology originates from the band\ninversion between the $s-$like and $p-$like orbitals that are contributed\ncompletely by the Hg and Te atoms, so the quantized edge states are restricted\nwithin the honeycomb HgTe monolayer. Meanwhile, the strong interaction between\nHgTe and Al$_2$O$_3$(0001) ensures high stability of the atomic structure.\nTherefore, the TI states may be realized in HgTe/Al$_2$O$_3$(0001) at high\ntemperature.",
        "positive": "Competing antiferroelectric and ferroelectric interactions in NaNbO3 :\n  Neutron diffraction and theoretical studies: Neutron diffraction studies using powder samples have been used to understand\nthe complex sequence of low temperature phase transitions of NaNbO3 in the\ntemperature range from 12 K-350 K. Detailed Rietveld analysis of the\ndiffraction data reveal that the antiferroelectric to ferroelectric phase\ntransition occurs on cooling around 73 K while the reverse ferroelectric to\nantiferroelectric transition occurs on heating at 245 K. However, the former\ntransformation is not complete till down to 12 K and there is unambiguous\nevidence for the presence of the ferroelectric R3c phase coexisting with an\nantiferroelectic phase (Pbcm) over a wide range of temperatures. The coexisting\nphases and reported anomalous smearing of the dielectric response akin to\ndipole glasses and relaxors observed in the same temperature range are\nconsistent with competing ferroelectric and antiferroelectric interactions in\nNaNbO3. We have carried out theoretical lattice dynamical calculations which\nreveal that the free energies of the antiferroelectric Pbcm and ferroelectric\nR3c phases are nearly identical over a wide range of temperature. The small\nenergy difference between the two phases is of interest as it explains the\nobserved coexistence of these phases over a wide range of temperature. The\ncomputed double well depths and energy barriers from paraelectric Pm m to\nantiferroelectric Pbcm and ferroelectric R3c phases in NaNbO3 are also quite\nsimilar, although the ferroelectric R3c phase has a slightly lower energy."
    },
    {
        "anchor": "Design and discovery of a novel Half-Heusler transparent hole conductor\n  made of all-metallic heavy elements: Metallic conductors that are optically transparent represent a rare breed of\ngenerally contraindicated physical properties that are nevertheless critically\nneeded for application where both functionalities are crucial. Such rare\nmaterials have traditionally been searched in the general chemical neighborhood\nof compounds containing metal oxides, expected to be wide gap insulators that\nmight be doped to induce conductivity.Focusing on the family of 18 valence\nelectron ABX compounds we have searched theoretically for the ability of the\ncompound's electronic structure to simultaneously lead to optical transparency,\nin parallel with the ability of its intrinsic defect structures to produce\nuncompensated free holes.This led to the prediction of a stable, never before\nsynthesized TaIrGe compound made of all-metal heavy atom compound as the \"best\nof class\" from the V-IX-IV group. Laboratory synthesis then found it to be\nstable in the predicted crystal structure and p-type transparent conductor with\nmeasured strong direct absorption of 3.36 eV and remarkably high (albeit not\npredicted) hole mobility of 2730 cm2/Vs at room temperature. This methodology\nopens the way to future searches of transparent conductors in unexpected\nchemical groups.",
        "positive": "Long-lived spin memory in Mn-doped GaAs: Time resolved study: We study the electron spin dynamics in p-type GaAs doped with magnetic Mn\nacceptors by means of time-resolved pump-probe and photoluminescence\ntechniques. Measurements in transverse magnetic fields show a long spin\nrelaxation time of 20 ns that can be uniquely related to electrons. Application\nof weak longitudinal magnetic fields above 100 mT extends the spin relaxation\ntimes up to microseconds which is explained by suppression of the\nBir-Aronov-Pikus spin relaxation for the electron on the Mn acceptor."
    },
    {
        "anchor": "High-pressure studies of MSb3 (M = Fe, Co) at quasi-hydrostatic\n  conditions: We present a comparative study of the unfilled CoSb3 and FeSb3 skutterudites\nand report on their compressibility studied by high-pressure synchrotron X-ray\ndiffraction. The equation of state for FeSb3 was received for the first time.\nThe third order Birch- Murnaghan isothermal equations of state were fitted to\nthe experimental data in the pressure ranges atm-34 GPa for CoSb3 and atm-14\nGPa for FeSb3. Bulk moduli of 95(5) GPa and 86(4) GPa have been obtained for\nCoSb3 and FeSb3, respectively. The bulk modulus of FeSb3 is in a contrast by\nabout 30% with literature value obtained indirectly. Anomaly was observed in\nthe diffraction pattern of CoSb3 at the pressures 34.4-39.6 GPa which is most\nprobably reasoned by structure transition.",
        "positive": "Silicene on Substrates: A Theoretical Perspective: Silicene, as the silicon analog of graphene, has been successfully fabricated\nby epitaxial growing on various substrates. Similar to free-standing graphene,\nfree-standing silicene possesses a honeycomb structure and Dirac-cone-shaped\nenergy band, resulting in many fascinating properties such as high carrier\nmobility, quantum spin Hall effect, quantum anomalous Hall effect, and quantum\nvalley Hall effect. The maintenance of the honeycomb crystal structure and the\nDirac cone of silicene is crucial for observation of its intrinsic properties.\nIn this review, we systematically discuss the substrate effects on the atomic\nstructure and electronic properties of silicene from a theoretical point of\nview, especially focusing on the changes of the Dirac cone."
    },
    {
        "anchor": "High thermal conductivity of high-quality monolayer boron nitride and\n  its thermal expansion: Heat management becomes more and more critical, especially in miniaturized\nmodern devices, so the exploration of highly thermally conductive materials\nwith electrical insulation and favorable mechanical properties is of great\nimportance. Here, we report that high-quality monolayer boron nitride (BN) has\na thermal conductivity (\\k{appa}) of 751 W/mK at room temperature. Though\nsmaller than that of graphene, this value is larger than that of cubic boron\nnitride (cBN) and only second to those of diamond and lately discovered cubic\nboron arsenide (BAs). Monolayer BN has the second largest \\k{appa} per unit\nweight among all semiconductors and insulators, just behind diamond, if density\nis considered. The \\k{appa} of atomically thin BN decreases with increased\nthickness. Our large-scale molecular dynamic simulations using Green-Kubo\nformalism accurately reproduce this trend, and the density functional theory\n(DFT) calculations reveal the main scattering mechanism. The thermal expansion\ncoefficients (TECs) of monolayer to trilayer BN at 300-400 K are also\nexperimentally measured, and the results are comparable to atomistic ab initio\nDFT calculations in a wider range of temperatures. Thanks to its wide bandgap,\nhigh thermal conductivity, outstanding strength, good flexibility, and\nexcellent thermal and chemical stability, atomically thin BN is a strong\ncandidate for heat dissipation applications, especially in the next generation\nof flexible electronic devices.",
        "positive": "Searching for new ferromagnetism precursors in two-dimensional model\n  materials in frame of local force theorem: In this work we conduct a numerical search of non-trivial mechanisms, leading\nto new tendencies towards long-range ferromagnetic ordering in two-dimensional\nmaterials. For this purpose we employ an original variant of pairwise\ninfinitesimal spin rotations technique to establish the magnetic transition\ntemperature as the rigid function of basic crystal's parameters. It favored the\nnumerical optimization of this function using modified genetic algorithm,\ndesigned to harvest local extrema. It resulted in revealing the moderate\nmetallicity, accompanied by essential orbital anisotropy, as the prime\nconfiguration, which provides the most favoring conditions to ferromagnetic\nordering, related to double-exchange and superexchange mechanisms."
    },
    {
        "anchor": "New, Lead Free, Perovskites With a Diffuse Phase Transition: NaNbO_{3} ~\n  Solid Solutions: Some of (1-x)NaNbO_3-(x)ABO_3 perovskite solid solutions exhibit a dramatic\ndiffusion of the dielectric permittivity epsilon' maximum and relaxor-type\nbehavior when the second component concentration exceeds a threshold value x_0.\nThe concentration phase transition to the relaxor-like phase is abrupt (of the\nfirst order kind) that is seen from the step in the dependence of the\nepsilon'(T) maximum temperature, T_m, on x. The precursor of this transition is\na giant (up to 100 K) temperature hysteresis of epsilon'(T). Some relaxor-like\nproperties appear even at x < x_0 in the course of cooling while disappear in\nthe course of heating. The experimental data obtained are qualitatively\ndescribed within a Landau-type phenomenological approach, assuming the\nrelaxor-type behavior to be local stress-induced.",
        "positive": "Controllable, driven phase transitions in the Fractional quantum Hall\n  states in bilayer graphene: Here we report from our theoretical studies that in biased bilayer graphene,\none can induce phase transitions from an incompressible fractional quantum Hall\nstate to a compressible state by tuning the bandgap at a given electron\ndensity. The nature of such phase transitions is different for weak and strong\ninter-layer coupling. Although for strong coupling more levels interact there\nare lesser number of transitions than for the weak coupling case. The\nintriguing scenario of tunable phase transitions in the fractional quantum Hall\nstates is unique to bilayer graphene and never before existed in conventional\nsemiconductor systems."
    },
    {
        "anchor": "Insights into regularity of 2D 3d transition metal monocarbides\n  formation: Recently several theoretical predictions were made about 2D planar FeC, CoC,\nNiC, and CuC while their bulk phases still remain unknown. Here, we present\ngeneralization of 2D family of 3d transition metal monocarbides (TMC) by\nsearching their stable configurations with DFT methods and evolutionary\nalgorithm. It is found that in the TMC row (TM = Sc-Cu) a tendency of 3D\nrocksalt phase formation is monotonously interchanging by 2D phase appearance,\nnamely planar orthorhombic TMC characterized by carbon dimers inside metal\nhexagons. Among them, orthorhombic CoC and FeC monocarbides would be likely\nformed rather than any other 2D metal carbide phase or metal/graphene\ninterface.",
        "positive": "Multiple Quintets via Singlet Fission in Ordered Films at Room\n  Temperature: The growing interest in harnessing singlet fission for photovoltaic\napplications stems from the possibility of generating two excitons from a\nsingle photon. Quantum efficiencies above unity have been reported, yet the\ncorrelation between singlet fission and intermolecular geometry is poorly\nunderstood. To address this, we investigated ordered solid solutions of\npentacene in p-terphenyl grown by organic molecular beam deposition. Two\nclasses of dimers are expected from the crystal structure - parallel and\nherringbone - with intrinsically distinctive electronic coupling. Using\nelectron paramagnetic resonance spectroscopy, we provide compelling evidence\nfor the formation of distinct quintet excitons at room temperature. These are\nassigned to specific pentacene pairs according to their angular dependence.\nThis work highlights the importance of controlling the intermolecular geometry\nand the need to develop adequate theoretical models to account for the\nrelationship between structure and electronic interactions in strongly-coupled,\nhigh-spin molecular systems."
    },
    {
        "anchor": "Predicting topological materials: symmetry-based indicator theories and\n  beyond: Though symmetry-based indicators formulae are powerful in diagnosing\ntopological states with a gapped band structure at/between any high-symmetry\npoints, it fails in diagnosing topological degeneracies when the compatibility\ncondition is violated. In such cases, we can only obtain information of whether\nthere is a band degeneracy at some high-symmetry points or along some\nhigh-symmetry lines by the compatibility condition. Under the framework of\nsymmetry-based indicator theories, we proposed an algorithm to diagnose the\ntopological band crossings in the compatibility condition-violating systems to\nobtain the whole topological information, by using the symmetry-based indicator\nformulae of their subgroups. In this paper, we reinterpret the algorithm in a\nsimpler way with two material examples preserving different topological states\nin spinless systems with time-reversal symmetry, discuss the limitation of the\nsymmetry-based indicator theories, and make further discussions on the\nalgorithm applying in spinful systems with time-reversal symmetry.",
        "positive": "Direct and Simultaneous Observation of Ultrafast Electron and Hole\n  Dynamics in Germanium: Understanding excited carrier dynamics in semiconductors is crucial for the\ndevelopment of photovoltaics and efficient photonic devices. However,\noverlapping spectral features in optical/NIR pump-probe spectroscopy often\nrender assignments of separate electron and hole carrier dynamics ambiguous.\nHere, ultrafast electron and hole dynamics in germanium nanocrystalline thin\nfilms are directly and simultaneously observed by attosecond transient\nabsorption spectroscopy (ATAS) in the extreme ultraviolet at the germanium\nM_{4,5}-edge (~30 eV). We decompose the ATAS spectra into contributions of\nelectronic state blocking and photo-induced band shifts at a carrier density of\n8*10^{20}cm^{-3}. Separate electron and hole relaxation times are observed as a\nfunction of hot carrier energies. A first order electron and hole decay of ~1\nps suggests a Shockley-Read-Hall recombination mechanism. The simultaneous\nobservation of electrons and holes with ATAS paves the way for investigating\nfew to sub-femtosecond dynamics of both holes and electrons in complex\nsemiconductor materials and across junctions."
    },
    {
        "anchor": "Chemical Functionalization of Graphene Nanoribbons by Carboxyl Groups on\n  Stone-Wales Defects: Using the density functional theory, we have demonstrated the chemical\nfunctionalization of semiconducting graphene nanoribbons (GNRs) with\nStone-Wales (SW) defects by carboxyl (COOH) groups. It is found that the\ngeometrical structures and electronic properties of the GNRs changed\nsignificantly, and the electrical conductivity of the system could be\nconsiderably enhanced by mono-adsorption and double-adsorption of COOH, which\nsensitively depends upon the axial concentration of SW defects COOH pairs\n(SWDCPs). With the increase of the axial concentration of SWDCPs, the system\nwould transform from semiconducting behavior to p-type metallic behavior. This\nfact makes GNRs a possible candidate for chemical sensors and nanoelectronic\ndevices based on graphene nanoribbons.",
        "positive": "Light-Matter Interactions in Two-Dimensional Transition Metal\n  Dichalcogenides: Dominant Excitonic Transitions in mono- and few-layer\n  MoX$_2$ and Band Nesting: We report ab initio calculations of the dielectric function of six mono- and\nbilayer molybdenum dichalcogenides based in a Bethe Salpether\nequation+G$_0$W$_0$ ansatz, focussing on the excitonic transitions dominating\nthe absorption spectrum up to an excitation energy of 3\\,eV. Our calculations\nsuggest that switching chalcogen atoms and the strength of interlayer\ninteractions should affect the detailed composition of the high 'C' peaks in\nexperimental optical spectra of molybdenum dichalcogenides and cause a\nsignificant spin-orbit-splitting of the contributing excitonic transitions in\nmonolayer MoSe$_2$ and MoTe$_2$. This can be explained through changes in the\nelectronic dispersion around the Fermi energy along the chalcogen series\nS$\\rightarrow$Se$\\rightarrow$Te that move the van-Hove singularities in the\ndensity of states of the two-dimensional materials along the\n\\textit{$\\Gamma$}-\\textit{K} line in the Brillouin zone. Further, we confirm\nthe distinct interlayer character of the '\\textsl{C}' peak transition in\nfew-layer MoS$_2$ that was predicted before from experimental data and show\nthat a similar behaviour can be expected for MoSe$_2$ and MoTe$_2$ as well."
    },
    {
        "anchor": "Cationic exchange in nanosized ZnFe2O4 spinel revealed by experimental\n  and simulated near-edge absorption structure: The non-equilibrium cation site occupancy in nanosized zinc ferrites (6-13\nnm) with different degree of inversion (0.2 to 0.4) was investigated using Fe\nand Zn K-edge x-ray absorption spectroscopy XANES and EXAFS, and magnetic\nmeasurements. The very good agreement between experimental and ab-initio\ncalculations on the Zn K-edge XANES region clearly show the large\nZn2+(A)--Zn2+[B] transference that takes place in addition to the\nwell-identified Fe3+[B]--Fe3+(A) one, without altering the long-range\nstructural order. XANES spectra features as a function of the spinel inversion\nwere shown to depend on the configuration of the ligand shells surrounding the\nabsorbing atom. This XANES approach provides a direct way to sense cationic\ninversion in these spinel compounds. We also demonstrated that a mechanical\ncrystallization takes place on nanocrystalline spinel that causes an increase\nof both grain and magnetic sizes and, simultaneously, generates a significant\naugment of the inversion.",
        "positive": "Initial oxidation of Fe-Al and Fe-Cr-Al alloys: Cr as an alumina booster: The boosting effect of Cr on the growth of the protective alumina scale on\nFe-Al alloys is investigated by x-ray photoelectron spectroscopy. Using low\noxygen pressure the surface chemistry of the alloys is monitored starting from\nthe first moments of oxidation. Chromium effect on the Fe-Al surface-bulk\nexchange is clearly detected by analyzing the measured surface concentrations\nwithin the atomic concentration models. Previous ab initio calculations agree\nwell with the present experiments."
    },
    {
        "anchor": "WyCryst: Wyckoff Inorganic Crystal Generator Framework: Generative design marks a significant data-driven advancement in the\nexploration of novel inorganic materials, which entails learning the symmetry\nequivalent to the crystal structure prediction (CSP) task and subsequent\nlearning of their target properties. Generative models have been developed in\nthe last few years that use custom Variational Autoencoders (VAEs), Generative\nAdversarial Networks (GANs), and diffusion models. While periodicity and global\nEuclidian symmetry in three dimensions through translations, rotations and\nreflections have recently been accounted for, symmetry constraints within\nallowed space groups have not. This is especially important because the final\nstep involves energy relaxation on the generated crystal structures to find the\nrelaxed crystal structure, typically using Density Functional Theory (DFT). To\naddress this explicitly, we introduce a generative design framework (WyCryst),\ncomposed of three pivotal components: 1) a Wyckoff position based inorganic\ncrystal representation, 2) a property-directed VAE model and 3) an automated\nDFT workflow for structure refinement. Our model selectively generates\nmaterials that follow the ground truth of unit cell space group symmetry by\nencoding the Wyckoff representation for each space group. We successfully\nreproduce a variety of existing materials: CaTiO3 (space group, SG No. 62 and\n221), CsPbI3 (SG No. 221), BaTiO3 (SG No. 160), and CuInS2 (SG No.122) for both\nground state as well as polymorphic structure predictions. We also generate\nseveral new ternary materials not found in the inorganic materials database\n(Materials Project), which are proved to be stable, retaining their symmetry,\nand we also check their phonon stability, using our automated DFT workflow\nhighlighting the validity of our approach. We believe our symmetry-aware\nWyCryst takes a vital step towards AI-driven inorganic materials discovery.",
        "positive": "Predicting A Novel Phase of 2D SiTe$_2$: Layered IV-VI$_2$ compounds often exist in the CdI$_2$ structure. Using the\nevolution algorithm and first-principles calculations, we predict a novel\nlayered structure of silicon ditelluride (SiTe$_2$) that is more stable than\nthe CdI$_2$ phase. The structure has a triclinic unit cell in its bulk form and\nexhibits the competition between the Si atoms' tendency to form tetrahedral\nbonds and the Te atoms' tendency to form hexagonal close-packing. The\nelectronic and vibrational properties of the predicted phase are investigated.\nThe effective mass of electron is small among 2D semiconductors, which is\nbeneficial for applications such as field-effect transistors. The vibrational\nRaman and IR spectra are calculated to facilitate future experimental\ninvestigations"
    },
    {
        "anchor": "Fabrication and characterization of pseudo-spin-MOSFET: Recently spin-transistors receive considerable attention as a\nhighly-functional building block of future integrated circuits. In order to\nrealize spin-transistors, it is essential that technology of efficient spin\ninjection/detection for semiconductor channel is established. However, this is\nnot so easy challenge owing to ferromagnet/semiconductor-interface-related\nseveral problems. In this paper, we demonstrate pseudo-spin-MOSFET (PS-MOSFET)\narchitecture that is a new circuit approach using an ordinary MOSFET and\nmagnetic tunnel junction (MTJ) to reproduce the functions of spin transistors.",
        "positive": "Single-crystal epitaxial europium iron garnet films with strain-induced\n  perpendicular magnetic anisotropy: structural, strain, magnetic, and spin\n  transport properties: Single-crystal europium iron garnet (EuIG) thin films epitaxially\nstrain-grown on gadolinium gallium garnet (GGG)(100) substrates using off-axis\nsputtering have strain-induced perpendicular magnetic anisotropy (PMA). By\nvarying the sputtering conditions, we have tuned the europium/iron (Eu/Fe)\ncomposition ratios in the films to tailor the film strains. The films exhibited\nan extremely smooth, particle-free surface with roughness as low as 0.1 nm as\nobserved using atomic force microscopy. High-resolution x-ray diffraction\nanalysis and reciprocal space maps showed in-plane epitaxial film growth, very\nsmooth film/substrate interface, excellent film crystallinity with a small full\nwidth at half maximum of 0.012$^{\\circ}$ in the rocking curve scans, and an\nin-plane compressive strain without relaxation. In addition, spherical\naberration-corrected scanning transmission electron microscopy showed an\natomically abrupt interface between the EuIG film and GGG. The measured\nsquarish out-of-plane magnetization-field hysteresis loops by vibrating sample\nmagnetometry in conjunction with the measurements from angle-dependent x-ray\nmagnetic dichroism demonstrated the PMA in the films. We have tailored the\nmagnetic properties of the EuIG thin films, including saturation magnetization\nranging from 71.91 to 124.51 emu/c.c. (increase with the (Eu/Fe) ratios),\ncoercive field from 27 to 157.64 Oe, and the strength of PMA field ($H_\\bot$)\nincreasing from 4.21 to 18.87 kOe with the in-plane compressive strain from\n-0.774 to -1.044%. We have also investigated spin transport in Pt/EuIG bi-layer\nstructure and evaluated the real part of spin mixing conductance to be\n$3.48\\times10^{14} {\\Omega}^{-1}m^{-2}$. We demonstrated the current-induced\nmagnetization switching with a low critical switching current density of\n$3.5\\times10^6 A/cm^2$, showing excellent potential for low-dissipation\nspintronic devices."
    },
    {
        "anchor": "Late stage, non-equilibrium dynamics in the dipolar Ising model: Magnetic domain structures are a fascinating area of study with interest\nderiving both from technological applications and fundamental scientific\nquestions. The nature of the striped magnetic phases observed in ultra-thin\nfilms is one such intriguing system. The non-equilibrium dynamics of such\nsystems as they evolve toward equilibrium has only recently become an area of\ninterest and previous work on model systems showed evidence of complex, slow\ndynamics with glass-like properties as the stripes order mesoscopically. To aid\nin the characterization of the observed phases and the nature of the\ntransitions observed in model systems we have developed an efficient method for\nidentifying clusters or domains in the spin system, where the clusters are\nbased on the stripe orientation. Thus we are able to track the growth and decay\nof such clusters of stripes in a Monte Carlo simulation and observe directly\nthe nature of the slow dynamics. We have applied this method to consider the\ngrowth and decay of ordered domains after a quench from a saturated magnetic\nstate to temperatures near and well below the critical temperature in the two\ndimensional dipolar Ising model. We discuss our method of identifying stripe\ndomains or clusters of stripes within this model and present the results of our\ninvestigations.",
        "positive": "Materials analysis and focused ion beam nanofabrication of topological\n  insulator Bi2Se3: Focused ion beam milling allows manipulation of the shape and size of\nnanostructures to create geometries potentially useful for opto-electronics,\nthermoelectrics, and quantum computing. We focus on using the ion beam to\ncontrol the thickness of Bi2Se3 and to create nanowires from larger structures.\nChanges in the material structure of Bi2Se3 nanomaterials that have been milled\nusing a focused ion beam are presented. In order to characterize the effects of\nion beam processing on the samples, we use a variety of techniques including\nanalytical transmission electron microscopy and atomic force microscopy. The\nresults show that while part of the material remains intact after shaping,\namorphous regions form where the beam has been used to thin the sample. For\nwires created by thinning the material down to the substrate, the sidewalls of\nthe wires appear intact based on diffraction images from samples cut at an\nangle, but thin crystalline regions remain at the wire edges. Even with the\nresulting defects, focused ion beam milling shows promise for directly\nfabricating intricate nanodevices of Bi2Se3."
    },
    {
        "anchor": "Do topology and ferromagnetism cooperate at the EuS/Bi$_2$Se$_3$\n  interface?: We probe the local magnetic properties of interfaces between the insulating\nferromagnet EuS and the topological insulator Bi$_2$Se$_3$ using low energy\nmuon spin rotation (LE-$\\mu$SR). We compare these to the interface between EuS\nand the topologically trivial metal, titanium. Below the magnetic transition of\nEuS, we detect strong local magnetic fields which extend several nm into the\nadjacent layer and cause a complete depolarization of the muons. However, in\nboth Bi$_2$Se$_3$ and titanium we measure similar local magnetic fields,\nimplying that their origin is mostly independent of the topological properties\nof the interface electronic states. In addition, we use resonant soft X-ray\nangle resolved photoemission spectroscopy (SX-ARPES) to probe the electronic\nband structure at the interface between EuS and Bi$_2$Se$_3$. By tuning the\nphoton energy to the Eu anti-resonance at the Eu $M_5$ pre-edge we are able to\ndetect the Bi$_2$Se$_3$ conduction band, through a protective Al$_2$O$_3$\ncapping layer and the EuS layer. Moreover, we observe a signature of an\ninterface-induced modification of the buried Bi$_2$Se$_3$ wave functions and/or\nthe presence of interface states.",
        "positive": "Exploring conformational energy landscape of glassy disaccharides by\n  CPMAS 13C NMR and DFT/GIAO simulations. II. Enhanced molecular flexibility in\n  amorphous trehalose: This paper deals with the comparative use of the chemical shift surfaces to\nsimulate experimental 13C CPMAS data on amorphous solid state disaccharides,\npaying particular attention to &#61537;-1-1 linkage of trehalose, to\n&#61538;-1,4 linkage between pyranose rings (lactose) and to linkage implying a\nfuranose ring (sucrose). The combination of molecular mechanics with DFT/GIAO\nab-initio methods provides reliable structural information on the\nconformational distribution in the glass. The results are interpreted in terms\nof an enhanced flexibility that trehalose experiences in amorphous solid state\ncompared to the other sugars. An attempt to relate this property to the balance\nbetween intra- and inter-molecular hydrogen bonding network in the glass is\npresented."
    },
    {
        "anchor": "Three-dimensional description of vibration-assisted electron knock-on\n  damage: Elastic knock-on is the main electron irradiation damage mechanism in metals\nincluding graphene. Atomic vibrations influence its cross-section, but only the\nout-of-plane direction has been considered so far in the literature. Here, we\npresent a full three-dimensional theory of knock-on damage including the effect\nof temperature and vibrations to describe ejection into arbitrary directions.\nWe thus establish a general quantitative description of electron irradiation\neffects through elastic scattering. Applying our methodology to in-plane jumps\nof pyridinic nitrogen atoms, we show their observed rates imply much stronger\ninelastic effects than in pristine graphene.",
        "positive": "Role of temperature-dependent spin model parameters in ultra-fast\n  magnetization dynamics: In the spirit of multi-scale modelling magnetization dynamics at elevated\ntemperature is often simulated in terms of a spin model where the model\nparameters are derived from first principles. While these parameters are mostly\nassumed temperature-independent and thermal properties arise from spin\nfluctuations only, other scenarios are also possible. Choosing bcc Fe as an\nexample, we investigate the influence of different kinds of model assumptions\non ultra-fast spin dynamics, where following a femtosecond laser pulse a sample\nis demagnetized due to a sudden rise of the electron temperature. While\ndifferent model assumptions do not affect the simulational results\nqualitatively, their details do depend on the nature of the modelling."
    },
    {
        "anchor": "Positive versus negative resistance response to hydrogenation in\n  palladium and its alloys: Resistive solid state sensors are widely used in multiple applications,\nincluding molecular and gas detection. Absorption or intercalation of the\ntarget species varies the lattice parameters and an effective thickness of thin\nfilms, which is usually neglected in analyzing their transport properties in\ngeneral and the sensor response in particular. Here, we explore the case of\npalladium-based thin films absorbing hydrogen and demonstrate that expansion of\nthickness is an important mechanism determining the magnitude and the very\npolarity of the resistance response to hydrogenation in high resistivity films.\nThe model of the resistance response that takes into account modifications of\nthickness was tested and confirmed in three Pd-based systems with variable\nresistivity: thin Pd films above and below the percolation threshold, thick\nPd-SiO2 granular composite films with different content of silica, and Pd-rich\nCoPd alloys where resistivity depends on Co concentration. Superposition of the\nbulk resistivity increase due to hydride formation and decrease of film\nresistance due to thickness expansion provides a consistent explanation of the\nhydrogenation response in both continuous and discontinuous films with\ndifferent structures and compositions.",
        "positive": "Cavity mediated manipulation of distant spin currents using\n  cavity-magnon-polariton: Using electrical detection of a strongly coupled spin-photon system comprised\nof a microwave cavity mode and two magnetic samples, we demonstrate the long\ndistance manipulation of spin currents. This distant control is not limited by\nthe spin diffusion length, instead depending on the interplay between the local\nand global properties of the coupled system, enabling systematic spin current\ncontrol over large distance scales (several centimeters in this work). This\nflexibility opens the door to improved spin current generation and manipulation\nfor cavity spintronic devices."
    },
    {
        "anchor": "Tailoring anomalous Nernst effect in stressed magnetostrictive film\n  grown onto flexible substrate: The anomalous Nernst effect in nanostructured magnetic materials is a key\nphenomenon to optimally control and employ the internal energy dissipated in\nelectronic devices, being dependent on for instance the magnetic anisotropy of\nthe active element. Thereby, here we report a theoretical and experimental\ninvestigation of the magnetic properties and anomalous Nernst effect in a\nflexible magnetostrictive film with induced uniaxial magnetic anisotropy and\nunder external stress. Specifically, we calculate the magnetization behavior\nand the thermoelectric voltage response from a theoretical approach for a\nplanar geometry and with a magnetic free energy density which takes into\naccount the induced uniaxial and magnetoelastic anisotropy contributions.\nExperimentally, we verify modifications of the effective magnetic anisotropy\nand thermoelectric voltage with the stress and explore the possibility of\ntailoring the anomalous Nernst effect in a flexible magnetostrictive film by\nmodifying both, the magnetic field and external stress. We find quantitative\nagreement between experiment and numerical calculations, thus elucidating the\nmagnetic and thermoelectric voltage behaviors, as well as providing evidence to\nconfirm the validity of the theoretical approach to describe the magnetic\nproperties and anomalous Nernst effect in ferromagnetic magnetostrictive films\nhaving uniaxial magnetic anisotropy and submitted to external stress. Hence,\nthe results place flexible magnetostrictive systems as a promising candidate\nfor active elements in functionalized touch electronic devices.",
        "positive": "Crystalline and magnetic structure of Ba2CuO3+\u03b4 investigated by\n  x-ray absorption spectroscopy and resonant inelastic x-ray scattering: Motivated by the recent synthesis of Ba$_2$CuO$_{3+\\delta}$ (BCO), a high\ntemperature superconducting cuprate with putative $d_{3z^2-r^2}$ ground state\nsymmetry, we investigated its electronic structure by means of Cu $L_3$ x-ray\nabsorption (XAS) and resonant inelastic x-ray scattering (RIXS) at the Cu $L_3$\nedge on a polycrystalline sample. We show that the XAS profile of BCO is\ncharacterised by two peaks associated to inequivalent Cu sites, and that its\nRIXS response features a single, sharp peak associated to crystal-field\nexcitations. We argue that these observations are only partially compatible\nwith the previously proposed crystal structure of BCO. Based on our\nspectroscopic results and on previously published powder diffraction\nmeasurements, we propose a crystalline structure characterized by two\ninequivalent Cu sites located at alternated planes along the $c$ axis:\nnominally trivalent Cu(1) belonging to very short Cu-O chains, and divalent\nCu(2) in the oxygen deficient CuO$_ {1.5}$ planes. We also analyze the\nlow-energy region of the RIXS spectra to estimate the magnitude of the magnetic\ninteractions in BCO and find that in-plane nearest neighbor superexchange\nexceeds 120~meV, similarly to that of other layered cuprates. Although these\nresults do not support the pure $d_{3z^2-r^2}$ ground state scenario, they hint\nat a significant departure from the common quasi-2D electronic structure of\nsuperconducting cuprates of pure $d_{x^2-y^2}$ symmetry."
    },
    {
        "anchor": "Inversely Prepolarized Piezoceramic Cantilever: A nonuniform piezoelectric cantilever with enhanced amplitude of vibration at\nresonances is proposed. The cantilever made of lead zirconate titanate (type of\nPZT-5H) containing inversely poled piezoelectric domains shows an advantageous\nincrease in vibration amplitude when compared to a single domain device. The\namplitude of vibrations is enhanced when the domain boundaries are located at\nthe nodes of vibration displacement. The vibration amplitude of a cantilever\nwith 2 or 3 periodically inverted domains is mostly affected at the 2nd or 3rd\nresonance frequency, respectively. The amplitudes are calculated using the\nFinite Element method (FEM).",
        "positive": "Impurity impact ionization avalanche in p-type diamond: Electrical conductivity of a highly boron doped chemical vapor deposited\ndiamond thin film has been studied at different temperatures under high\nelectric field conditions. Current-voltage characteristics have been measured\nusing pulsed technique to reduce thermal effects. Experimental results evidence\ndeep impurity impact ionization avalanche in p-type diamond up to room\ntemperature."
    },
    {
        "anchor": "Engineering Anomalously Large Electron Transport in Topological\n  Semimetals: Anomalous transport of topological semimetals has generated significant\ninterest for applications in optoelectronics, nanoscale devices, and\ninterconnects. Understanding the origin of novel transport is crucial to\nengineering the desired material properties, yet their orders of magnitude\nhigher transport than single-particle mobilities remain unexplained. This work\ndemonstrates the dramatic mobility enhancements result from phonons primarily\nreturning momentum to electrons due to phonon-electron dominating over\nphonon-phonon scattering. Proving this idea, proposed by Peierls in 1932,\nrequires tuning electron and phonon dispersions without changing symmetry,\ntopology, or disorder. This is achieved by combining de Haas - van Alphen\n(dHvA), electron transport, Raman scattering, and first-principles calculations\nin the topological semimetals MX$_2$ (M=Nb, Ta and X=Ge, Si). Replacing Ge with\nSi brings the transport mobilities from an order magnitude larger than single\nparticle ones to nearly balanced. This occurs without changing the crystal\nstructure or topology and with small differences in disorder or Fermi surface.\nSimultaneously, Raman scattering and first-principles calculations establish\nphonon-electron dominated scattering only in the MGe$_2$ compounds. Thus, this\nstudy proves that phonon-drag is crucial to the transport properties of\ntopological semimetals and provides insight to further engineer these\nmaterials.",
        "positive": "Non-existence of the s-f transition in structures of solid gadolinium at\n  pressure: Gadolinium has long been believed to undergo a high pressure phase transition\nwith a volume collapse around 5%. Theoretical explanations have focused on the\nidea of electrons transferring from the extended s-orbital to the compact\nf-orbital. However, experimental measurement has been unable to detect any\nassociated change in the magnetic properties of the f-electrons. Here we\nresolve this discrepancy by showing that there is no significant volume\ncollapse, beyond what is typical in high pressure phase transformations. We\npresent density functional theory calculations of solid gadolinium under high\npressure using a range of methods, and revisit the experimental situation using\nX-ray diffraction (XRD). The standard lanthanide pressure-transformation\nsequence involving different stackings of close-packed planes: hcp to 9R to\ndhcp to fcc to d-fcc is reproduced. The so-called \"volume collapsed\"\nhigh-pressure phase is shown to be an unusual stacking of close-packed planes,\nwith Fddd symmetry and a density change less than 2%. The distorted fcc (d-fcc)\nstructure is revealed to arise as a consequence of antiferromagnetism. The\ntheoretical results are shown to be remarkably robust to various treatments of\nthe f-electrons. The key result is that there is no XRD evidence for volume\ncollapse in Gadolinium. The sequence of phase transitions is well described by\nstandard DFT. There is no need for special treatment of the f-electrons or\nevidence of f-electron bonding. Noting previous spectroscopic evidence is that\nthere is no change in the f-electrons we conclude that high pressure Gadolinium\nhas no complicated f-electron physics such as Mott-Hubbard, Kondo or valence\ntransition."
    },
    {
        "anchor": "Cleaning graphene : a first quantum/classical molecular dynamics\n  approach: Graphene outstanding properties created a huge interest in the condensed\nmatter community and unprecedented fundings at the international scale in the\nhope of application developments. Recently, there have been several reports of\nincomplete removal of the polymer resists used to transfer as-grown graphene\nfrom one substrate to another, resulting in altered graphene transport\nproperties. Finding a large-scale solution to clean graphene from adsorbed\nresidues is highly desirable and one promising possibility would be to use\nhydrogen plasmas. In this spirit, we couple here quantum and classical\nmolecular dynamics simulations to explore the kinetic energy ranges required by\natomic hydrogen to selectively etch a simple residue, a CH3 group, without\nirreversibly damaging the graphene. For incident energies in the 2-15 eV range,\nthe CH3 radical can be etched by forming a volatile CH4 compound which leaves\nthe surface, either in the CH4 form or breaking into CH3+H fragments, without\nfurther defect formation. At this energy, adsorption of H atoms on graphene is\npossible and further annealing will be required to recover pristine graphene.",
        "positive": "Illustrative view on the magnetocrystalline anisotropy of adatoms and\n  monolayers: Even though it has been known for decades that the magnetocrystalline\nanisotropy is linked to the spin-orbit coupling (SOC), the mechanism how it\narises for specific systems is still subject of debate. We focused on finding\nmarkers of SOC in the density of states (DOS) and on employing them for\nunderstanding the source of magnetocrystalline anisotropy for the case of\nadatoms and monolayers. Fully relativistic ab-initio KKR-Green function\ncalculations were performed for Fe, Co, and Ni adatoms and monolayers on\nAu(111) to investigate changes in the orbital-resolved DOS due to a rotation of\nmagnetization. In this way one can see that a significant contribution to the\nmagnetocrystalline anisotropy for adatoms comes from pushing of the SOC-split\nstates above or below the Fermi level. As a result of this, the\nmagnetocrystalline anisotropy energy crucially depends on the position of the\nenergy bands of the adatom with respect to the Fermi level of the substrate.\nThis view is supported by model crystal field Hamiltonian calculations."
    },
    {
        "anchor": "Anomalous Hall effect in insulating Ga1-xMnxAs: We have investigated the effect of doping by Te on the anomalous Hall effect\nin Ga1-xMnxAs (x = 0.085). For this relatively high value of x the temperature\ndependence of resistivity shows an insulating behavior. It is well known that\nin Ga1-xMnxAs the Mn ions naturally act as acceptors. Additional doping by Te\ndonors decreases the Curie temperature and increases the anomalous Hall\nresistivity. With increasing Te concentration the long-range ferromagnetic\norder in Ga1-xMnxAs eventually disappears, and paramagnetic-to-spin glass\ntransition is observed instead. The critical concentration of holes required\nfor establishing ferromagnetic order in Ga1-xMnxAs (x = 0.085) has been\nestimated by using the magnetic polaron percolation theory proposed by Kaminski\nand Das Sarma [Phys.Rev.Lett. 88, 247202 (2002)].",
        "positive": "Local detection of X-ray spectroscopies with an in-situ AFM: The in situ combination of Scanning Probe Microscopies (SPM) with X-ray\nmicrobeams adds a variety of new possibilities to the panoply of synchrotron\nradiation techniques. In this paper we describe an optics-free AFM/STM that can\nbe directly installed on synchrotron radiation end stations for such combined\nexperiments. The instrument can be used just for AFM imaging of the\ninvestigated sample or can be used for detection of photoemitted electrons with\na sharp STM-like tip, thus leading to the local measure of the X-ray absorption\nsignal. Alternatively one can can measure the flux of photon impinging on the\nsharpest part of the tip to locally map the pattern of beams diffracted from\nthe sample. In this paper we eventually provide some examples of local\ndetection of XAS and diffraction."
    },
    {
        "anchor": "Fine-tuning the functional properties of carbon nanotubes via the\n  interconversion of encapsulated molecules: Tweaking the properties of carbon nanotubes is a prerequisite for their\npractical applications. Here we demonstrate fine-tuning the electronic\nproperties of single-wall carbon nanotubes via filling with ferrocene\nmolecules. The evolution of the bonding and charge transfer within the tube is\ndemonstrated via chemical reaction of the ferrocene filler ending up as\nsecondary inner tube. The charge transfer nature is interpreted well within\ndensity functional theory. This work gives the first direct observation of a\nfine-tuned continuous amphoteric doping of single-wall carbon nanotubes.",
        "positive": "Infrared conductivity of metallic (III,Mn)V ferromagnets: We present a theory of the infrared conductivity and absorption coefficients\nof metallic (III,Mn)V ferromagnetic semiconductors. We find that the\nconductivity is dominated by inter-valence-band transitions that produce peaks\nat $\\hbar \\omega \\sim 220 {\\rm meV}$ and obscure the broadened Drude peak. We\ndemonstrate that transverse f-sum rule measurements can be used to extract\naccurate values for the free carrier density, bypassing the severe\ncharacterization difficulties that have till now been created by the large\nanomalous Hall effect in these materials."
    },
    {
        "anchor": "On the magnetic nanostructure of a Co-Cu alloy processed by\n  high-pressure torsion: In this study, a preparation route of Co-Cu alloys with soft magnetic\nproperties by high-pressure torsion deformation is introduced. Nanocrystalline,\nsupersaturated single-phase microstructures are obtained after deformation of\nCo-Cu alloys, which are prepared from an initial powder mixture with\nCo-contents above 70 wt.%. Isochronal annealing treatments up to 400{\\deg}C\nfurther reveal a remarkable microstructural stability. Only at 600{\\deg}C, the\nsupersaturated phase decomposes into two fcc-phases. The coercivity, measured\nby SQUID as a function of annealing temperature, remains significantly below\nthe value for bulk-Co in all states investigated. In order to understand the\nmeasured magnetic properties in detail, a quantitative analysis of the magnetic\nmicrostructure is carried out by magnetic force microscopy and correlated to\nthe observed changes in coercivity. Our results show that the rising coercivity\ncan be explained by a magnetic hardening effect occurring in context with\nspinodal decomposition.",
        "positive": "Thermodynamic Driving Forces for Substrate Atom Extraction by Adsorption\n  of Strong Electron Acceptor Molecules: A quantitative structural investigation is reported, aimed at resolving the\nissue of whether substrate adatoms are incorporated into the monolayers formed\nby strong molecular electron acceptors deposited onto metallic electrodes. A\ncombination of normal-incidence X-ray standing waves, low energy electron\ndiffraction, scanning tunnelling microscopy and X-ray photoelectron\nspectroscopy measurements demonstrate that the systems TCNQ and F4TCNQ on\nAg(100) lie at the boundary between these two possibilities and thus represent\nideal model systems with which to study this effect. A room-temperature\ncommensurate phase of adsorbed TCNQ is found not to involve Ag adatoms, but to\nadopt an inverted bowl configuration, long predicted but not previously\nidentified experimentally. By contrast, a similar phase of adsorbed F4TCNQ does\nlead to Ag adatom incorporation in the overlayer, the cyano endgroups of the\nmolecule being twisted relative to the planar quinoid ring. Density functional\ntheory (DFT) calculations show that this behaviour is consistent with the\nadsorption energetics. Annealing of the commensurate TCNQ overlayer phase leads\nto an incommensurate phase that does appear to incorporate Ag adatoms. Our\nresults indicate that the inclusion (or exclusion) of metal atoms into the\norganic monolayers is the result of both thermodynamic and kinetic factors."
    },
    {
        "anchor": "Probing phonon softening in ferroelectrics by the scanning probe\n  microwave spectroscopy: Microwave measurements have recently been successfully applied to measure\nferroelectric materials on the nanoscale, including detection of polarization\nswitching and ferroelectric domain walls. Here we discuss the question whether\nscanning probe microscopy (SPM) operating at microwave frequency can identify\nthe changes associated with the soft phonon dynamics in a ferroic. The\nanalytical expressions for the electric potential, complex impedance and\ndielectric losses are derived and analyzed, since these physical quantities are\nlinked to experimentally-measurable properties of the ferroic. As a ferroic we\nconsider virtual or proper ferroelectric with an optic phonon mode that softens\nat a Curie point. We also consider a decay mechanism linked to the conductance\nof the ferroic, and thus manifesting itself as the dielectric loss in the\nmaterial. Our key finding is that the influence of the soft phonon dispersion\non the surface potential distribution, complex impedance and dielectric losses\nare evidently strong in the vicinity (10-30 K) of the Curie temperature.\nFurthermore, we quantified how the spatial distribution and frequency spectra\nof the complex impedance and the dielectric losses react on the dynamics of the\nsoft phonons near the Curie point. These results set the stage for\ncharacterization of polar phase transitions with nanoscale microwave\nmeasurements, providing a complementary approach to well established\nelectromechanical measurements for fundamental understanding of ferroelectric\nproperties as well as their applications in telecommunication and computing.",
        "positive": "With no Color and Scent (part II): Metal and Alloy\n  Microstructures-Handmade Replicas of Natural Objects: As a continuation of work on metal and alloy \"plants\" synthesis on porous\nmembranes by means of pulsed current electroplating volume metallic\nmicrostructures resembling such natural objects as shells, cabbage leaves,\nmushrooms are grown and presented in their modest elegance. Such structures are\nformed from PdNi and PdCo alloys as well as Ag, Cu and Ni in conditions defined\nby the shape of membrane pores and the parameters of the pulsed current. It is\nshown that the obtained complex structures are formed by layers of metallic\nnanowires as a result of their self-assembly while growing during the pulsed\ncurrent electroplating process. Depending on the shape of the membrane and the\nregime of the pulsed current electroplating either one type of shell-like\nstructures or various structures can be grown."
    },
    {
        "anchor": "Limits on electron quality in suspended graphene due to flexural phonons: The temperature dependence of the mobility in suspended graphene samples is\ninvestigated. In clean samples, flexural phonons become the leading scattering\nmechanism at temperature $T \\gtrsim 10\\,\\,$K, and the resistivity increases\nquadratically with $T$. Flexural phonons limit the intrinsic mobility down to a\nfew $\\text{m}^2/\\text{Vs}$ at room $T$. Their effect can be eliminated by\napplying strain or placing graphene on a substrate.",
        "positive": "Structural and magnetic properties of Co-Mn-Sb thin films: Thin Co-Mn-Sb films of different compositions were investigated and utilized\nas electrodes in alumina based magnetic tunnel junctions with CoFe counter\nelectrode. The preparation conditions were optimized with respect to magnetic\nand structural properties. The Co-Mn-Sb/Al-O interface was analyzed by X-ray\nabsorption spectroscopy and magnetic circular dichroism with particular focus\non the element-specific magnetic moments. Co-Mn-Sb crystallizes in different\ncomplex cubic structures depending on its composition. The magnetic moments of\nCo and Mn are ferromagnetically coupled in all cases. A tunnel magneto\nresistance ratio of up to 24 % at 13K was found and indicates that Co-Mn-Sb is\nnot a ferromagnetic half-metal. These results are compared to recent works on\nthe structure and predictions of the electronic properties."
    },
    {
        "anchor": "A systematic study of the dynamics of chain formation in\n  electrorheological fluids: We report a systematic study of the dynamics of chain formation in\nelectrorheological (ER) fluids using Brownian Dynamics simulations. The\nparameters of the system such as applied electric field, polarizability, dipole\nmoment, friction coefficient, and number density are expressed in reduced units\nand changed in a wide range in order to map the system's behavior as a function\nof them. We define time constants obtained from bi-exponential fits to time\ndependence of various physical quantities such as dipolar energy, diffusion\nconstant, and average chain length. The smaller time constant is associated\nwith the formation of shorter chains (pairs, triplets, and so on), while the\nlarger time constant is associated with the formation of longer chains in the\nregime of those that overarch the simulation cell. We use the approximation\nthat the dipole moments are induced by the applied electric field only, as\nusual in the literature. However, we report preliminary results for the case\nwhen particle-particle polarization is also possible.",
        "positive": "In-situ fabrication of Mo6S6 nanowire terminated edges in monolayer\n  molybdenum disulfide: Edge structures are highly relevant to the electronic, magnetic and catalytic\nproperties of two-dimensional (2D) transition metal dichalcogenides (TMDs) and\ntheir one dimensional (1D) counterpart, i.e., nanoribbons, which should be\nprecisely tailored for the desirable applications. In this work, we report the\nformation of novel Mo6S6 nanowire (NW) terminated edges in a monolayer\nmolybdenum disulfide (MoS2) via an e-beam irradiation process combined with\nhigh temperature heating in a scanning transmission electron microscope (STEM).\nAtomic structures of NW terminated edges and the dynamic formation process were\nobserved experimentally. Further analysis shows that NW terminated edge could\nform on both Mo-zigzag (ZZ) edge and S-ZZ edge which can exhibit even higher\nstability superior to the pristine zigzag (ZZ) and armchair (AC) edge. In\naddition, the analogous edge structures can be also formed in MoS2 nanoribbon\nand other TMDs material such as MoxW1-xSe2. We believe that the presence of\nthese novel edge structures in 2D and 1D TMD materials may provide novel\nproperties and new opportunities for their versatile applications including\ncatalytic, spintronic and electronic devices."
    },
    {
        "anchor": "Formation and dissociation reactions of complexes involving interstitial\n  carbon and oxygen defects in silicon: We present a detailed first-principles study which explores the\nconfigurational space along the relevant reactions and migration paths\ninvolving the formation and dissociation of interstitial carbon-oxygen\ncomplexes, $\\mathrm{C_{i}O_{i}}$ and $\\mathrm{C_{i}O_{2i}}$, in silicon. The\nformation/dissociation mechanisms of $\\mathrm{C_{i}O_{i}}$ and\n$\\mathrm{C_{i}O_{2i}}$ are found as occurring via capture/emission of mobile\n$\\mathrm{C_{i}}$ impurities by/from O-complexes anchored to the lattice. The\nlowest activation energies for dissociation of $\\mathrm{C_{i}O_{i}}$ and\n$\\mathrm{C_{i}O_{2i}}$ into smaller moieties are 2.3 eV and 3.1 eV,\nrespectively. The first is compatible with the observed annealing temperature\nof $\\mathrm{C_{i}O_{i}}$ , which occurs at around 400 $^{\\circ}$C, and below\nthe threshold for $\\mathrm{O_{i}}$ diffusion. The latter exceeds significantly\nthe measured activation energy for the annealing of $\\mathrm{C_{i}O_{2i}}$\n($E_{\\mathrm{a}}=2.55$ eV). We propose that instead of dissociation, the actual\nannealing mechanism involves the capture of interstitial oxygen by\n$\\mathrm{C_{i}O_{2i}}$, thus being governed by the migration barrier of\n$\\mathrm{O_{i}}$ ($E_{\\mathrm{m}}=2.53$ eV). The study is also accompanied by\nmeasurements of hole capture cross sections and capture barriers of\n$\\mathrm{C_{i}O_{i}}$ and $\\mathrm{C_{i}O_{2i}}$. In combination with\npreviously reported data, we find thermodynamic donor transitions which are\ndirectly comparable to the first-principles results. The two levels exhibit\nclose features, conforming to a model where the electronic character of\n$\\mathrm{C_{i}O_{2i}}$ can be described by that of $\\mathrm{C_{i}O_{i}}$\nperturbed by a nearby O atom.",
        "positive": "Microscopic effects of Dy-doping in the topological insulator Bi2Te3: Magnetic doping with transition metal ions is the most widely used approach\nto break timereversal symmetry in a topological insulator, a prerequisite for\nunlocking the TIs exotic potential. Recently, we reported the doping of Bi2Te3\nthin films with rare earth ions, which, owing to their large magnetic moments,\npromise commensurately large magnetic gap openings in the topological surface\nstates. However, only when doping with Dy has a sizable gap been observed in\nangle-resolved photoemission spectroscopy, which persists up to\nroom-temperature. Although disorder alone could be ruled out as a cause of the\ntopological phase transition, a fundamental understanding of the magnetic and\nelectronic properties of Dy:Bi2Te3 remained elusive. Here, we present an X-ray\nmagnetic circular dichroism, polarized neutron reflectometry, muon spin\nrotation, and resonant photoemission study of the microscopic magnetic and\nelectronic properties. We find that the films are not simply paramagnetic but\nthat instead the observed behavior can be well explained by the assumption of\nslowly fluctuating, inhomogeneous magnetic patches with increasing volume\nfraction as the temperature decreases. At liquid helium temperatures, a large\neffective magnetization can be easily introduced by the application of moderate\nmagnetic fields, implying that this material is very suitable for proximity\ncoupling to an underlying ferromagnetic insulator or in a heterostructure with\ntransition metal-doped layers. However, the introduction of some charge\ncarriers by the dopants cannot be excluded at least in these highly doped\nsamples. Nevertheless, we find that the magnetic order is not mediated via the\nconduction channel in these rare earth doped samples and therefore magnetic\norder and carrier concentration are expected to be independently controllable.\nThis is not generally the case for transition metal doped topological\ninsulators."
    },
    {
        "anchor": "Valence Bond Order and Antiferromagnetism in Silicene - ab initio\n  Results: Silicene and Graphene are similar and have $\\pi$-$\\pi^*$ bands. However band\nwidth in silicene is only a third of graphene. It results in a substantial\nincrease in the ratio of Hubbard U to band width W, U/W $\\sim$ 0.5 in graphene\nto $\\sim 1$ in silicene. This enhancement, 2 dimensionality and phenomenology\nsuggest a Mott insulator based ground state for silicene (G. Baskaran,\narXiv:1309.2242). We lend support to the above proposal by showing, in an\nab-initio calculation, that unlike graphene, silicene has two instabilities: i)\na valence bond (Kekule) dimerization and ii) a weak two sublattice\nantiferromagnetic order. Presence of these instabilities, in the absence of\nfermi surface nesting, point to Mott localization, \\textit{within the frame\nwork of ab-initio scheme}. Substrate dependent structural reconstructions seen\nexperimentally in silicene are interpreted as generalized Kekule bond order.",
        "positive": "Thermoelectric properties of Pr3Rh4Sn13-type Yb3Co4Ge13 and Yb3Co4Sn13\n  compounds: Crystallographic data and thermoelectric properties (from 240 K up to 380 K)\nof Yb3Co4Ge13, Yb3Co4Sn13 compounds and Yb2CeCo4Ge13 and Yb2.3La0.7Co4Ge13\nsolid solutions are reported. The Seebeck coefficients, electric resistance and\nthermal conductivity increase monotonically with increasing temperature from\n240 to 380 K for all the compounds. The Seebeck coefficient is S = 14 - 27 \\mu\nV//K for Yb3Co4Sn13, and S = -21 -- -12 \\mu V/K for Yb3Co4Ge13. The\nsubstitution of Yb for cerium or lanthanum in Yb3Co4Ge13 shifts the Seeebeck\ncoefficient to positive values. The Yb3Co4Sn13 has a maximal ZT parameter from\navailable Pr3Rh4Sn13-type compounds. The ZT parameter of Yb3Co4Sn13 compound\nincreases from 0.006 up to 0.017 with increasing temperature from 240 K to 380\nK."
    },
    {
        "anchor": "Carrier mobilities of Janus transition metal dichalcogenides monolayers\n  studied by Born effective charge and first-principles calculation: Two-dimensional (2D) Janus transition metal dichalcogenides (TMDs) are a new\nclass of materials with unique physical properties. However, the carrier\nmobility of most Janus TMDs calculated by deformation potential theory (DPT) is\nnot reliable due to the unconsidered part of lattice scattering. In this work,\nwe propose a new method of Born effective charge (BEC) to calculate the carrier\nmobility of Janus TMDs by including the important factors that neglected in the\nDPT. The BEC could be used in the calculation of both pure and defective Janus\nTMDs by employing density functional perturbation theory. We have figured out\nthe relationship between the carrier mobility and the value of BEC, which is\nthe lower the absolute BEC, the higher the electron or hole mobility. Using the\nnew method, we have calculated the carrier mobility of commonly studied Janus\nTMDs with and without defect. The method may shed light on the high-throughout\ncalculation of selecting high carrier mobility 2D materials.",
        "positive": "Measures of Basicity in Silicate Minerals Revealed by Alkali Exchange\n  Energetics: The energies of the alkali exchange reactions are computed from density\nfunctional calculations for a series of alkali silicate minerals.\nFirst-principles calculations are compared against (1) experiment; (2)\nthermodynamic models; (3) calculations using empirical interatomic potentials\n(with both polarizable shell model potentials and pairwise potentials with\npartial charges); and (4) empirical correlations based on optical basicity and\nPauling bond strength. The first-principles calculations correlate well with\nexperimental values. The shell model potentials appear to account for Si-O-Si\nversus Si-O oxygen basicity, but don't recover the differences in basicity\nbetween Al-O-Si and Si-O-Si donors. The pair potentials don't even\nqualitatively reproduce the reactivity trends established in the\nfirst-principles calculations. Empirical correlations based on optical basicity\nand Pauling bond strength successfully rank-order the exchange energies, but\nfail to describe the large difference in basicity between Si-O-Si and Si-O\noxygen atoms. Knowing which models are capable of predicting ion exchange\nenergies in silicate minerals improves understanding of the physics of bonding\nin ion-exchanged glasses."
    },
    {
        "anchor": "Magnetization reversal in the anisotropy-dominated regime using\n  time-dependent magnetic fields: We study magnetization reversal using various r.f. magnetic pulses. We show\nnumerically that switching is possible with simple sinusoidal pulses; however\nthe optimum approach is to use a frequency-swept (chirped) r.f. magnetic pulse,\nthe shape of which can be derived analytically. Switching times of the order of\nnanoseconds can be achieved with relatively small r.f. fields, independent of\nthe anisotropy's strength.",
        "positive": "Field-induced Topological Hall effect in antiferromagnetic axion\n  insulator candidate EuIn$_2$As$_2$: The magnetic topological materials have attracted significant attention due\nto their potential realization of variety of novel quantum phenomena.\nEuIn$_2$As$_2$ has recently been theoretically recognized as a long awaited\nintrinsic antiferromagnetic bulk axion insulator. However, the experimental\nstudy on transport properties arising from the topological states in this\nmaterial is scarce. In this paper, we perform the detailed magnetoresistance\n(MR) and Hall measurements to study the magnetotransport properties of this\nmaterial. We find that the transport is strongly influenced by the spin\nconfiguration of the Eu moments from the concomitant change in the field\ndependence of the MR and that of the magnetization below the N\\'eel\ntemperature. Most importantly, an anomalous Hall effect (AHE) and a large\ntopological Hall effect (THE) are observed. We suggest that the AHE is\noriginated from a nonvanishing net Berry curvature due to the helical spin\nstructure and that the THE is attributed to the formation of a noncoplanar spin\ntexture with a finite scalar spin chirality induced by the external magnetic\nfield in EuIn$_2$As$_2$. Our studies provide a platform to understand the\ninfluence of the interplay between the topology of electronic bands and the\nfield-induced magnetic structure on magnetoelectric transport properties. In\naddition, our observations give a hint to realize axion insulator states and\nhigh-order topological insulator states through manipulating the magnetic state\nof EuIn$_2$As$_2$."
    },
    {
        "anchor": "The concept of multifractal elasticity: A new type of elasticity of random (multifractal) structures is suggested. A\nclosed system of constitutive equations is obtained on the basis of two\nproposed phenomenological laws of reversible deformations of multifractal\nstructures. The results may be used for predictions of the mechanical behavior\nof materials with multifractal microstructure, as well as for the estimation of\nthe metric, information, and correlation dimensions using experimental data on\nthe elastic behavior of materials with random microstructure.",
        "positive": "Elastocaloric effect associated with the martensitic transition in\n  shape-memory alloys: The elastocaloric effect in the vicinity of the martensitic transition of a\nCu-Zn-Al has been studied by inducing the transition by strain or stress\nmeasurements. While transition trajectories show significant differences, the\nentropy change associated with the whole transformation (\\DeltaSt) is\ncoincident in both kind of experiments since entropy production is small\ncompared to \\DeltaSt. The values agree with estimations based on the Clausius-\nClapeyron equation. The possibility of using these materials for mechanical\nrefrigeration is also discussed."
    },
    {
        "anchor": "First-principles simulation of light-ion microscopy of graphene: The extreme sensitivity of 2D materials to defects and nanostructure requires\nprecise imaging techniques to verify presence of desirable and absence of\nundesirable features in the atomic geometry. Helium-ion beams have emerged as a\npromising materials imaging tool, achieving up to 20 times higher resolution\nand 10 times larger depth-of-field than conventional or environmental scanning\nelectron microscopes. Here, we offer first-principles theoretical insights to\nadvance ion-beam imaging of atomically thin materials by performing real-time\ntime-dependent density functional theory simulations of single impacts of\n10-200 keV light ions in free-standing graphene. We predict that detecting\nelectrons emitted from the back of the material (the side from which the ion\nexits) would result in up to 3 times higher signal and up to 5 times higher\ncontrast images, making 2D materials especially compelling targets for ion-beam\nmicroscopy. We also find that the charge induced in the graphene equilibrates\non a sub-fs time scale, leading to only slight disturbances in the carbon\nlattice that are unlikely to damage the atomic structure for any of the beam\nparameters investigated here.",
        "positive": "Infinite spin diffusion length of any spin polarization along direction\n  perpendicular to effective magnetic field from Dresselhaus and Rashba\n  spin-orbit couplings with identical strengths in (001) GaAs quantum wells: In this note, we show that the latest spin grating measurement of spin helix\nby Koralek {\\em et al.} [Nature {\\bf 458}, 610 (2009)] provides strong evidence\nof the infinite spin diffusion length of any spin polarization along the\ndirection perpendicular to the effective magnetic field from the\n  Dresselhaus and Rashba spin-orbit couplings with identical strengths in\n$(001)$ GaAs quantum wells, predicted by Cheng {\\em et al.} [Phys. Rev. B {\\bf\n75}, 205328 (2007)]."
    },
    {
        "anchor": "HR-EBSD investigation of dislocations in loaded slip bands: This scientific paper aims to study the correlation between the mobile and\nimmobile dislocation within loaded slip bands observed in situ, shedding light\non the underlying plastic deformation mechanisms. The full Nye lattice\ncurvature tensor was measured using high-resolution electron-backscatter\ndiffraction (HR-EBSD) to estimate the dislocations density. We observed that\ndislocation activities at the slip band were mainly from immobile edge\ndislocations to maintain the geometrical distortion of the slip band. A burst\nof dislocations was induced at the slip band associated with hot spots related\nto the intense strain gradient.",
        "positive": "Computation of the expectation value of the spin operator $\\hat{S}^2$\n  for the Spin-Flip Bethe-Salpeter Equation: Spin-flip methods applied to excited-state approaches like the Bethe-Salpeter\nEquation allow access to the excitation energies of open-shell systems, such as\nmolecules and defects in solids. The eigenstates of these solutions, however,\nare generally not eigenstates of the spin operator $\\hat{S}^2$. Even for simple\ncases where the excitation vector is expected to be, for example, a triplet\nstate, the value of $\\langle \\hat{S}^2 \\rangle$ may be found to differ from\n2.00; this difference is called ``spin contamination.'' The expectation values\n$\\langle \\hat{S}^2 \\rangle$ must be computed for each excitation vector, to\nassist with the characterization of the particular excitation and to determine\nthe amount of spin contamination of the state. Our aim is to provide for the\nfirst time in the spin-flip methods literature a comprehensive resource on the\nderivation of the formulas for $\\langle \\hat{S}^2 \\rangle$ as well as its\ncomputational implementation. After a brief discussion of the theory of the\nSpin-Flip Bethe-Salpeter Equation and some examples further illustrating the\nneed for calculating $\\langle \\hat{S}^2 \\rangle$, we present the derivation for\nthe general equation for computing $\\langle \\hat{S}^2 \\rangle$ with the\neigenvectors from an SF-BSE calculation, how it is implemented in a Python\nscript, and timing information on how this calculation scales with the size of\nthe SF-BSE Hamiltonian."
    },
    {
        "anchor": "Power Spectral Density Analysis and Correlation of Growth and Morphology\n  of Ni Films on Si Substate: Ni thin films grown by thermal evaporation and sputtering under different\ndeposition conditions are characterized for structural and morphological\nproperties using X-ray diffraction (XRD) and atomic force microscopy (AFM)\ntechniques. XRD results suggested the growth of polycrystalline fcc Ni phase\nfor all the samples. Morphological characteristics of the films were compared\nby analysing AFM data for root mean square roughness, height-height correlation\nfunction and power spectral density (PSD) measurements. Applying fractal and\nk-correlation fitting models to the PSD data, different morphological\nparameters are quantified. The study suggested that Ni films grown at higher\nsubstrate temperature (~ 150 oC) by thermal evaporation and at low Ar pressure\n(~ 0.2 Pa) by sputtering techniques yielded films of small surface roughness\nwith Brownian fractal self-affine surfaces.",
        "positive": "Functionalized Tellurene; a candidate large-gap 2D Topological Insulator: The discovery of group IV and V elemental Xene's which exhibit topologically\nnon-trivial characters natively in their honeycomb lattice structure (HLS) has\nled to extensive efforts in realising analogous behaviour in group VI elemental\nmonolayers. Although; it was theoretically concluded that group VI elemental\nmonolayers cannot exist as HLS but recent experimental evidence suggests\notherwise. In this letter we report that, HLS of group VI elemental monolayer\n(such as, Tellurene) can be realised to be dynamically stable when\nfunctionzalised with Oxygen. The functionalization leads to, peculiar orbital\nfiltering effects (OFE) and broken spatial inversion symmetry which gives rise\nto the non-trivial topological character. The exotic quantum behaviour of this\nsystem is characterized by, spin-orbit coupling induced large-gap $\\approx$\n0.36 eV with isolated Dirac cone along the edges indicating perspective room\ntemperature spin-transport applications. Further investigations of spin Hall\nconductivity and the Berry curvatures unravel high conductivity as compared to\npreviously explored Xene's. The non-trivial topological character is quantified\nin terms of the $\\mathbb{Z}_2$ invaraint as $\\nu =$ 1 and Chern number\n$\\mathit{C} =$ 1. Also, for practical purposes, we report that,\n\\textit{h}BN/TeO/\\textit{h}BN quantum-wells can be strain engineered to realize\na sizable non-trivial gap ($\\approx$ 0.11 eV). We finally conclude that,\nfunctionalization of group VI elemental monolayer with Oxygen gives rise to,\nexotic quantum properties which are robust against surface oxidation and\ndegradations while providing viable electronic degrees of freedom for\nspintronic applications."
    },
    {
        "anchor": "Layer Construction of Topological Crystalline Insulator LaSbTe: Topological crystalline insulator (TCI) is one of the symmetry-protected\ntopological states. Any TCI can be deformed into a simple product state of\nseveral decoupled two-dimensional (2D) topologically nontrivial layers in its\nlattice respecting its crystalline symmetries called the layer construction\n(LC) limit. In this work, based on first-principles calculations we have\nrevealed that both tetragonal LaSbTe (t-LaSbTe) and orthorhombic LaSbTe\n(o-LaSbTe) can be interpreted as stacking of 2D topological insulators in each\nlattice space. The structural phase transition from t-LaSbTe to o-LaSbTe due to\nsoft phonon modes demonstrates how the real space change can lead to the\nmodification of topological states. Their symmetry-based indicators and\ntopological invariants have been analyzed based on LC. We propose that LaSbTe\nis an ideal example demonstrating the LC paradigm, which bridges the crystal\nstructures in real space to the band topology in momentum space.",
        "positive": "Creep failure of honeycombs made by rapid prototyping: Additive manufacture and rapid prototyping are versatile methods for the\ngeneration of lattice materials for applications in the creep regime. However,\nthese techniques introduce defects that can degrade the macro-scopic creep\nstrength. In the present study, the uniaxial tensile response of\ntwo-dimensional PMMA lattices is measured in the visco-plastic regime: tests\nare performed at 100C which is slightly below the glass transition temperature\nT g of PMMA. Both as-manufactured defects (Plateau borders and strut thickness\nvariation) and as-designed defects (missing cell walls, solid inclusions, and\nrandomly perturbed joints) are introduced. The dispersion in macroscopic\nstrength is measured for relative densities in the range of 0.07 to 0.19. It is\nobserved that initial failure of the lattice is diffuse in nature: struts fail\nat a number of uncorrelated locations, followed by the development of a single\nmacroscopic crack transverse to the loading direction. In contrast, the same\nPMMA lattice fails in a correlated, brittle manner at room temperature. An FE\nstudy is performed to gain insight into the diffuse failure mode and the role\nplayed by as-manufactured defects, including the dispersion in tensile strength\nof individual struts of the lattice. A high damage tolerance to as-designed\ndefects is observed experimentally: there is negligible knock-down in strength\ndue to the removal of cell walls or to the presence of solid inclusions. These\nfindings aid the design and manufacture of damage tolerant lattices in the\ncreep regime."
    },
    {
        "anchor": "Parameterisation of non-collinear energy landscapes in itinerant magnets: The magnetic force theorem provides convenient ways to study exchange\ninteractions in magnetic systems. However, it is well known that short range\ninteractions in itinerant magnetic systems are poorly described with the\nconventional use of the theorem and numerous strategies have been developed\nover the years to overcome this deficiency. In this study, we discuss this\nissue in the context of the frozen magnon method and find that a\nself-consistent approach is in general preferable. Moreover, an extended\nHeisenberg model is suggested in order to better describe finite deviations\nfrom the magnetic ground state and is shown through cross-validation to give a\nsuperior description of the interactions in non-collinear magnetic\nconfigurations compared to the regular Heisenberg model. The present study thus\nsupplies a fully self-consistent method for systematic investigations of\nexchange interactions beyond the standard Heisenberg model. This may prove\nrelevant to high-throughput computational materials science, e.g., in\ndeveloping high moment materials for the magnetic storage industry.",
        "positive": "Localized surface plasmon resonance in silver nanoparticles: Atomistic\n  first-principles time-dependent density-functional theory calculations: We observe using ab initio methods that localized surface plasmon resonances\nin icosahedral silver nanoparticles enter the asymptotic region already between\ndiameters of 1 and 2 nm, converging close to the classical quasistatic limit\naround 3.4 eV. We base the observation on time-dependent density-functional\ntheory simulations of the icosahedral silver clusters Ag$_{55}$ (1.06 nm),\nAg$_{147}$ (1.60 nm), Ag$_{309}$ (2.14 nm), and Ag$_{561}$ (2.68 nm). The\nsimulation method combines the adiabatic GLLB-SC exchange-correlation\nfunctional with real time propagation in an atomic orbital basis set using the\nprojector-augmented wave method. The method has been implemented for the\nelectron structure code GPAW within the scope of this work. We obtain good\nagreement with experimental data and modeled results, including photoemission\nand plasmon resonance. Moreover, we can extrapolate the ab initio results to\nthe classical quasistatically modeled icosahedral clusters."
    },
    {
        "anchor": "Glassy magnetic behavior in the metamagnetic DyAlO3 doped with Cr: Magnetic properties of DyAl$_{0.926}$Cr$_{0.074}$O$_3$ and DyAlO$_3$ were\nstudied. We found that both compounds are antiferromagnetic with a low N\\'eel\ntransition temperature. At higher temperatures the magnetic characteristics\nshow a Curie-Weiss dependence. The N\\'eel temperature disappears when a field\nof about 2 T is applied, the system changes from an antiferromagnetic to a weak\nferromagnetic behavior due to a metamagnetic transition. Furthermore, AC\nmagnetic measurements in the Cr doped compound, at different frequencies, show\na spin glass-like behavior. These transitions were studied and corroborated by\nspecific heat measurements. We found the presence of metamagnetism and spin\nglass in the compound doped with chromium, determining that the small addition\nof chromium atoms modifies the magnetic properties of the compound DyAlO$_3$,\nresulting in new features such as the spin glass-like behavior.",
        "positive": "Tunable Weyl and Dirac states in the nonsymmorphic compound\n  $\\rm\\mathbf{CeSbTe}$: Recent interest in topological semimetals has lead to the proposal of many\nnew topological phases that can be realized in real materials. Next to Dirac\nand Weyl systems, these include more exotic phases based on manifold band\ndegeneracies in the bulk electronic structure. The exotic states in topological\nsemimetals are usually protected by some sort of crystal symmetry and the\nintroduction of magnetic order can influence these states by breaking time\nreversal symmetry. Here we show that we can realize a rich variety of different\ntopological semimetal states in a single material, $\\rm CeSbTe$. This compound\ncan exhibit different types of magnetic order that can be accessed easily by\napplying a small field. It allows, therefore, for tuning the electronic\nstructure and can drive it through a manifold of topologically distinct phases,\nsuch as the first nonsymmorphic magnetic topological material with an\neight-fold band crossing at a high symmetry point. Our experimental results are\nbacked by a full magnetic group theory analysis and ab initio calculations.\nThis discovery introduces a realistic and promising platform for studying the\ninterplay of magnetism and topology."
    },
    {
        "anchor": "Allotropic transition of Dirac semimetal \u03b1-Sn to superconductor\n  \u03b2-Sn induced by irradiation of focused ion beam: Diamond-type structure allotrope {\\alpha}-Sn is attracting much attention as\na topological Dirac semimetal (TDS). In this study, we demonstrate that\n{\\alpha}-Sn undergoes a phase transition to another allotrope {\\beta}-Sn with\nsuperconductivity at low temperature by irradiating with a focused Ga ion beam\n(FIB). To clarify the transition mechanism, we performed X-ray photoemission\nspectroscopy (XPS) measurements on an {\\alpha}-Sn thin film irradiated with FIB\nand an as-grown {\\alpha}-Sn thin film. The XPS results suggest that the local\nannealing, which is one of the side effects of FIB, causes the transformation\nfrom {\\alpha}-Sn into {\\beta}-Sn. Furthermore, the difference in the chemical\nstates between {\\alpha}-Sn and {\\beta}-Sn can be quantitatively explained by\nthe crystal structures rather than the degree of metallicity reflecting the\nconductivity. These results propose a new way of fabricating TDS/superconductor\nin-plane heterostructures based on {\\alpha}-Sn and {\\beta}-Sn.",
        "positive": "Minimizing Residues and Strain in 2D Materials Transferred from PDMS: Integrating layered two-dimensional (2D) materials into 3D heterostructures\noffers opportunities for novel material functionalities and applications in\nelectronics and photonics. In order to build the highest quality\nheterostructures, it is crucial to preserve the cleanliness and morphology of\n2D material surfaces that come in contact with polymers such as PDMS during\ntransfer. Here we report that substantial residues and up to ~0.22% compressive\nstrain can be present in monolayer MoS$_{2}$ flakes transferred using PDMS. We\nshow that a UV-ozone pre-cleaning of the PDMS surface before exfoliation\nsignificantly reduces organic residues on transferred MoS$_{2}$ flakes. An\nadditional 200$^{\\circ}$C vacuum anneal after transfer efficiently removes\ninterfacial bubbles and wrinkles as well as accumulated strain, thereby\nrestoring the surface morphology of transferred flakes to their native state.\nOur recipe is important for building clean heterostructures of 2D materials and\nincreasing the reproducibility and reliability of devices based on them."
    },
    {
        "anchor": "Oxidation of copper during physical sputtering deposition: mechanism,\n  avoidance and utilization: In this paper, oxidation of Cu during physical sputtering deposition in a\nhigh purity and low pressure Ar atmosphere without introducing O2 gas flow was\nstudied systemically. It was found that various flexible Cu-based films could\nbe obtained by simply adjusting deposition parameters. Electrical and optical\ntesting results showed that the achieved pure Cu films and Cu+Cu2O composite\nfilms both presented an intriguing combination of metal and semiconductor\ncharacteristics. It is expected that such Cu-based films with a superior\nconductivity and a solar-window bandgap may have fascinating potential\napplications such as in high electron mobility transistors, electrodes and\nsolar cells. Further, the oxidation mechanisms of Cu under different deposition\nparameters and the main O2 source during physical sputtering deposition were\nalso explored.",
        "positive": "Relationship between granularity of antiferromagnet and exchange bias: We studied exchange bias in magnetic multilayers incorporating\nantiferromagent CoO doped with up to 35 atomic percent of Pt. The exchange bias\nincreased with doping in epitaxial films, but did not significantly change in\npolycrystalline films at the lowest measured temperature of 5 K, and decreased\nat higher temperatures. We explain our results by the increased granularity of\nthe doped antiferromagnetic films, resulting in simultaneous enhancement of the\nuncompensated spin density and reduction of the magnetic stability of\nantiferromagnetic grains."
    },
    {
        "anchor": "Antiferromagnetic to Ferrimagnetic Phase Transition and Possible Phase\n  Coexistence in Polar Magnets (Fe$_{1-x}$Mn$_x$)$_2$Mo$_3$O$_8$: In the present work, magnetic properties of single crystal\n(Fe$_{1-x}$Mn$_x$)$_2$Mo$_3$O$_8$ ($0<x<1$) have been studied by performing\nextensive measurements. A detailed magnetic phase diagram is built up, in which\nantiferromagnetic state dominates for $x<0.25$ and ferrimagnetic phase arises\nfor $x>0.3$. Meanwhile, sizeable electric polarization of spin origin is\ncommonly observed in all samples, no matter what the magnetic state is. For the\nsamples hosting a ferrimagnetic state, square-like magnetic hysteresis loops\nare revealed, while the remnant magnetization and coercive field can be tuned\ndrastically by simply varying the Mn-content or temperature. Possible\ncoexistence of the antiferromagnetic and ferrimagnetic phases is proposed to be\nresponsible for the remarkable modulation of magnetic properties in the\nsamples.",
        "positive": "Giant directional birefringence in multiferroic ferroborate: Many technological applications are based on electric or magnetic order of\nmaterials, for instance magnetic memory. Multiferroics are materials which\nexhibit electric and magnetic order simultaneously. Due to the coupling of\nelectric and magnetic effects, these materials show a strong potential to\ncontrol electricity and magnetism and, more generally, the properties and\npropagation of light. One of the most fascinating and counter-intuitive recent\nresults in multiferroics is directional anisotropy, the asymmetry of light\npropagation with respect to the direction of propagation. The absorption in the\nmaterial can be different for forward and backward propagation of light, which\nin extreme case may lead to complete suppression of absorption in one\ndirection. Another remarkable effect in multiferroics is directional\nbirefringence, i.e. different velocities of light for different directions of\npropagation. In this paper, we demonstrate giant directional birefringence in a\nmultiferroic samarium ferroborate. The effect is easily observed for linear\npolarization of light in the range of millimeter-wavelengths, and survives down\nto very low frequencies. The dispersion and absorption close to the\nelectromagnon resonance can be controlled and fully suppressed in one\ndirection. Therefore, samarium ferroborate is a universal tool for optical\ncontrol: with a magnetic field as an external parameter it allows switching\nbetween two functionalities: polarization rotation and directional anisotropy."
    },
    {
        "anchor": "Synchronization of spin-transfer oscillators driven by stimulated\n  microwave currents: We have simulated the non-linear dynamics of networks of spin-transfer\noscillators. The oscillators are magnetically uncoupled but electrically\nconnected in series. We use a modified Landau-Lifschitz- Gilbert equation to\ndescribe the motion of each oscillator in the presence of the oscillations of\nall the others. We show that the oscillators of the network can be synchronized\nnot only in frequency but also in phase. The coupling is due to the microwave\ncomponents of the current induced in each oscillator by the oscillations in all\nthe other oscillators. Our results show how the emitted microwave power of\nspin-transfer oscillators can be considerably enhanced by current-induced\nsynchronization in an electrically connected network. We also discuss the\npossible application of our synchronization mechanism to the interpretation of\nthe surprisingly narrow microwave spectrum in some isolated spin-transfer\noscillators.",
        "positive": "Structural, magnetic, and transport properties of Co$_2$FeSi Heusler\n  films: We report the deposition of thin Co$_2$FeSi films by RF magnetron sputtering.\nEpitaxial (100)-oriented and L2$_1$ ordered growth is observed for films grown\non MgO(100) substrates. (110)-oriented films on Al$_2$O$_3$(110) show several\nepitaxial domains in the film plane. Investigation of the magnetic properties\nreveals a saturation magnetization of 5.0 $mu_B/f.u.$ at low temperatures. The\ntemperature dependence of the resistivity $rho_{xx}(T)$ exhibits a crossover\nfrom a T^3.5 law at T<50K to a T^1.65 behaviour at elevated temperatures.\n$rho_{xx}(H)$ shows a small anisotropic magnetoresistive effect. A weak\ndependence of the normal Hall effect on the external magnetic field indicates\nthe compensation of electron and hole like contributions at the Fermi surface."
    },
    {
        "anchor": "Modeling and Reconstructing Complex Heterogeneous Materials From\n  Lower-Order Spatial Correlation Functions Encoding Topological and Interface\n  Statistics: The versatile physical properties of heterogeneous materials are intimately\nrelated to their complex microstructures, which can be statistically\ncharacterized and modelled using various spatial correlation functions\ncontaining key structural features of the material's phases. An important\nrelated problem is to inversely reconstruct the material microstructure from\nlimited morphological information contained in the correlation functions. Here,\nwe present in details a generalized lattice-point (GLP) method based on the\nlattice-gas model of heterogeneous materials that efficiently computes a\nspecific correlation function by updating the corresponding function associated\nwith a slightly different microstructure. This allows one to incorporate the\nwidest class of lower-order correlation functions utilized to date, including\nthose encoding topological connectedness information and interface statistics,\ninto the Yeong-Torquato stochastic reconstruction procedure, and thus enables\none to obtain much more accurate renditions of virtual material microstructure,\nto determine the information content of various correlation functions and to\nselect the most sensitive microstructural descriptors for the material of\ninterest. The utility of our GLP method is illustrated by modelling and\nreconstructing a wide spectrum of random heterogeneous materials, including\n\"clustered\" RSA disks, a metal-ceramic composite, a two-dimensional slice of a\nFontainebleau sandstone and a binary laser-speckle pattern, among other\nexamples.",
        "positive": "Nearly massless Dirac fermions hosted by Sb square net in BaMnSb2: Layered compounds AMnBi2 (A=Ca, Sr, Ba, or rare earth element) have been\nestablished as Dirac materials. Dirac electrons generated by the\ntwo-dimensional (2D) Bi square net in these materials are normally massive due\nto the presence of a spin-orbital coupling (SOC) induced gap at Dirac nodes.\nHere we report that the Sb square net in an isostructural compound BaMnSb2 can\nhost nearly massless Dirac fermions. We observed strong Shubnikov-de Haas (SdH)\noscillations in this material. From the analyses of the SdH oscillations, we\nfind key signatures of Dirac fermions, including light effective mass\n(~0.052m0; m0, mass of free electron), high quantum mobility (1280 cm2V-1S-1)\nand a Pi Berry phase accumulated along cyclotron orbit. Compared with AMnBi2,\nBaMnSb2 also exhibits much more significant quasi two-dimensional (2D)\nelectronic structure, with the out-of-plane transport showing nonmetallic\nconduction below 120K and the ratio of the out-of-plane and in-plane\nresistivity reaching ~670. Additionally, BaMnSb2 also exhibits an\nantiferromagnetic order with a weak ferromagnetic component. The combination of\nnearly massless Dirac fermions on quasi-2D planes with a magnetic order makes\nBaMnSb2 an intriguing platform for seeking novel exotic phenomena of massless\nDirac electrons."
    },
    {
        "anchor": "A theoretical analysis of the chemical bonding and electronic structure\n  of graphene interacting with Group IA and Group VIIA elements: We propose a new class of materials, which can be viewed as graphene\nderivatives involving Group IA or Group VIIA elements, forming what we refer to\nas graphXene. We show that in several cases large band gaps can be found to\nopen up, whereas in other cases a semimetallic behavior is found. Formation\nenergies indicate that under ambient conditions, sp$^3$ and mixed sp$^2$/sp$^3$\nsystems will form. The results presented allow us to propose that by careful\ntuning of the relative concentration of the adsorbed atoms, it should be\npossible to tune the band gap of graphXene to take any value between 0 and 6.4\neV.",
        "positive": "Very Large Tunneling Magnetoresistance in Layered Magnetic Semiconductor\n  CrI$_3$: Magnetic layered van der Waals crystals are an emerging class of materials\ngiving access to new physical phenomena, as illustrated by the recent\nobservation of 2D ferromagnetism in Cr2Ge2Te6 and CrI3. Of particular interest\nin semiconductors is the interplay between magnetism and transport, which has\nremained unexplored. Here we report first magneto-transport measurements on\nexfoliated CrI3 crystals. We find that tunneling conduction in the direction\nperpendicular to the crystalline planes exhibits a magnetoresistance as large\nas 10 000 %. The evolution of the magnetoresistance with magnetic field and\ntemperature reveals that the phenomenon originates from multiple transitions to\ndifferent magnetic states, whose possible microscopic nature is discussed on\nthe basis of all existing experimental observations. This observed dependence\nof the conductance of a tunnel barrier on its magnetic state is a new\nphenomenon that demonstrates the presence of a strong coupling between\ntransport and magnetism in magnetic van der Waals semiconductors."
    },
    {
        "anchor": "Noncollinearity effects on magnetocrystalline anisotropy for\n  $R_2$Fe$_{14}$B magnets: We present a theoretical investigation of the magnetocrystalline anisotropy\n(MA) in $R_2$Fe$_{14}$B ($R$ is a rare-earth element) magnets in consideration\nof the non-collinearity effect (NCE) between the $R$ and Fe magnetization\ndirections. In particular, the temperature dependence of the MA of\nDy$_2$Fe$_{14}$B magnets is detailed in terms of the $n$th-order MA constant\n(MAC) $K_n(T)$ at a temperature $T$. The features of this constant are as\nfollows: $K_1(T)$ has a broad plateau in the low-temperature range and $K_2(T)$\npersistently survives in the high-temperature range. The present theory\nexplains these features in terms of the NCE on the MA by using numerical\ncalculations for the entire temperature range, and further, by using a\nhigh-temperature expansion. The high-temperature expansion for $K_n(T)$ is\nexpressed in the form of\n$K_n(T)=\\kappa_1(T)\\left[1+\\delta(T)\\right][-\\delta(T)]^{n-1}$, where\n$\\kappa_1(T)$ is the part without the NCE and $\\delta(T)$ is a correction\nfactor for the NCE introduced in this study. We also provide a convenient\nexpression to evaluate $K_n(T)$, which can be determined only by a second-order\ncrystalline electric field coefficient and an effective exchange field.",
        "positive": "Divergent phonon angular momentum driven by temperature and strain: The phonon angular momentum (PAM) may exhibit exotic temperature dependence\nas it is sensitive to the phonon lifetime. Constant phonon-lifetime\napproximation fails to depict such behavior. Here, we study the PAM of AlN,\nGaN, and graphene-like boron nitride (g-BN) monolayer with full consideration\nof phonon lifetime using first-principles calculations. We show that wurtzite\nAlN and GaN acquire divergent PAM at low temperatures from their lowest-lying\nphonon branches. The g-BN monolayer, on the other hand, does not have finite\nPAM at equilibrium structure. Rather it shows intriguing strain-dependence in\nPAM; the compressive strain greater than the critical size generates divergent\nPAM at low temperatures due to the divergent lifetime of TA phonons. As PAM\ncouples with rotational excitations in solids associated with charge, spin, or\nelectromagnetic fields, our study demonstrates a possibility of mechanical and\nthermal engineering of such excitations."
    },
    {
        "anchor": "Canonical magnetic insulators with isotropic magnetoelectric coupling: We have performed an exhaustive representation-theory-based search for the\nsimplest structures allowing isotropic magnetoelectric coupling. We find 30\nsuch structures, all sharing a common pattern of atomic displacements in the\ndirection of atomic magnetic moments. We focus on one of these 30 canonical\nstructures and find that it is generically realized in a class of fractionally\nsubstituted pyrochlore compounds with an all-in-all-out magnetic order.\nFurthermore, we find that these substituted pyrochlore compounds have a\nsubstantial Chern-Simons orbital magnetoelectric component (\\theta=0.1--0.2).\nWhile this component is also formally present in strong Z_2 topological\ninsulators (\\theta=\\pi), its effects are observable there only if time-reversal\nsymmetry is broken at the surface.",
        "positive": "Determination and prediction of the fretting crack initiation:\n  introduction of the (P,Q,N) representation and definition of a variable\n  process volume: In this work, the crack nucleation under fretting loading is investigated\nexperimentally with a damage tolerant 2024 aluminium alloy. A new method is\nintroduced to determine its condition with respect to all loading parameters\nincluding the number of fretting cycles. Further work deals with the prediction\nof this threshold using the Smith-Watson-Topper criterion. New developments are\npresented, in particular a process volume of variable size is introduced in the\ncomputations of the fretting crack initiation."
    },
    {
        "anchor": "High-pressure structural study of a-Mn: solving a three decades-old\n  mystery: Manganese, in the a-Mn structure, has been studied using synchrotron powder\nx-ray diffraction in a diamond anvil cell up to 220 GPa at room temperature\ncombined with density functional calculations (DFT). The experiment reveals an\nextended pressure stability of the a-Mn phase up to the highest pressure of\nthis study, in contrast with previous experimental and theoretical studies. On\nthe other hand, calculations reveal that the previously predicted hcp-Mn phase\nbecomes lower in enthalpy than the a-Mn phase above 160 GPa. The apparent\ndiscrepancy is explained due to a substantial electron transfer between Mn\nions, which stabilizes the a-Mn phase through the formation of ionic bonding\nbetween monatomic ions under pressure.",
        "positive": "Reflectivity Anisotropy Spectra of Cu- and Ag- (110) surfaces from {\\it\n  ab initio} theory: We are able to disentagle the effects of the intraband and interband parts of\nthe bulk dielectric function on the bare dielectric anisotropy of the surface.\nWe show how the position, sign and amplitude of the structures observed in such\nspectra depend on the above quantities. The lineshape of all the calculated\nstructures agree very well with the ones observed experimentally for samples\ntreated by suitable surface cleaning. In particular, we reproduce the observed\nsingle peak structure of Ag at high energy, found to represent a state of the\nclean surface different from the one giving the originally observed double peak\nstructure. This results is not reproduced by the 'local field' model."
    },
    {
        "anchor": "Work function and surface stability of tungsten-based thermionic\n  electron emission cathodes: Materials that exhibit a low work function and therefore easily emit\nelectrons into vacuum form the basis of electronic devices used in applications\nranging from satellite communications to thermionic energy conversion. W-Ba-O\nis the canonical materials system that functions as the thermionic electron\nemitter used commercially in a range of high power electron devices. However,\nthe work functions, surface stability, and kinetic characteristics of a\npolycrystalline W emitter surface are still not well understood or\ncharacterized. In this study, we examined the work function and surface\nstability of the eight lowest index surfaces of the W-Ba-O system using Density\nFunctional Theory methods. We found that under the typical thermionic cathode\noperating conditions of high temperature and low oxygen partial pressure, the\nmost stable surface adsorbates are Ba-O species with compositions in the range\nof Ba0.125O to Ba0.25O per surface W atom, with O passivating all dangling W\nbonds and Ba creating work function-lowering surface dipoles. Wulff\nconstruction analysis reveals that the presence of O and Ba significantly\nalters the surface energetics and changes the proportions of surface facets\npresent under equilibrium conditions. Analysis of previously published data on\nW sintering kinetics suggests that fine W particles in the size range of\n100-500 nm may be at or near equilibrium during cathode synthesis, and thus may\nexhibit surface orientation fractions well-described by the calculated Wulff\nconstruction.",
        "positive": "Accelerated Band Offset Prediction in Semiconductor Interfaces with DFT\n  and Deep Learning: We introduce a computational framework to predict band offsets of\nsemiconductor interfaces using density functional theory (DFT) and graph neural\nnetworks (GNN). As a first step, we benchmark DFT based work function and\nelectron affinity values for surfaces against experimental data with accuracies\nof 0.29 eV and 0.39 eV. Similarly, we evaluate band offset values using\nindependent unit (IU) and alternate slab junction (ASJ) models leading to\naccuracies of 0.45 eV and 0.22 eV respectively. During ASJ structure\ngeneration, we use Zur's algorithm along with a unified GNN force-field to\ntackle the conformation challenges of interface design. At present, we have 300\nsurface work functions calculated with DFT, from which we can compute 44850 IU\nband offsets as well as 250 directly calculated ASJ band offsets. Finally, as\nthe space of all possible heterojunctions is too large to simulate with DFT, we\ndevelop generalized GNN models to quickly predict band edges with an accuracy\nof 0.26 eV. We use such models to predict relevant quantities including\nionization potentials, electron affinities, and IU-based band offsets. We\nestablish simple rules using the above models to pre-screen potential\nsemiconductor devices from a vast pool of nearly 1.4 trillion candidate\ninterfaces."
    },
    {
        "anchor": "Direct observations of nucleation in a nondilute multicomponent alloy: The chemical pathways leading to gamma-prime(L1_2)-nucleation from nondilute\nNi-5.2 Al-14.2 Cr at.%, gamma(f.c.c.), at 873 K are followed with radial\ndistribution functions and isoconcentration surface analyses of direct-space\natom-probe tomographic images. Although Cr atoms initially are randomly\ndistributed, a distribution of congruent Ni3Al short-range order domains (SRO),\n<R> =0.6 nm, results from Al diffusion during quenching. Domain site occupancy\ndevelops as their number density increases leading to Al-rich phase separation\nby gamma-prime-nucleation, <R>=0.75 nm, after SRO occurs.",
        "positive": "What is in a Name: Defining -High Entropy- Oxides: High entropy oxides are emerging as an exciting new avenue to design highly\ntailored functional behaviors that have no traditional counterparts. Study and\napplication of these materials are bringing together scientists and engineers\nfrom physics, chemistry, and materials science. The diversity of each of these\ndisciplines comes with perspectives and jargon that may be confusing to those\noutside of the individual fields, which can result in miscommunication of\nimportant aspects of research. In this perspective, we provide examples of\nresearch and characterization taken from these different fields to provide a\nframework for classifying the differences between compositionally complex\noxides, high entropy oxides, and entropy stabilized oxides, which is intended\nto bring a common language to this emerging area. We highlight the critical\nimportance of understanding a materials crystallinity, composition, and mixing\nlength scales in determining its true definition."
    },
    {
        "anchor": "Diffuse phase transition and electrical properties of lead-free\n  piezoelectric (LixNa1-x)NbO3 (0.04 to x to 0.20) ceramics near morphotropic\n  phase boundary: Temperature-dependent dielectric permittivity of lead-free (LixNa1-x)NbO3 for\nnominal x = 0.04-0.20, prepared by solid state reaction followed by sintering,\nwas studied to resolve often debated issue pertaining to exactness of\nmorphotropic phase boundary (MPB) location along with structural aspects and\nphase stability in the system near MPB. Interestingly, a diffuse phase\ntransition has been observed in the dielectric permittivity peak arising from\nthe disorder induced in A-site and structural frustration in the perovskite\ncell due to Li substitution. A partial phase diagram has been proposed based on\ntemperature-dependent dielectric permittivity studies. The room temperature\npiezoelectric and ferroelectric properties were investigated and the ceramics\nwith x = 0.12 showed relatively good electrical properties (d33 = 28 pC/N, kp =\n13.8%, Qm = 440, Pr = 12.5 {micro}C/cm2, EC = 43.2 kV/cm, Tm = 340 oC). These\nparameter values make this material suitable for piezoelectric resonator and\nfilter applications. Moreover, a high dielectric permittivity (= 2703) with\nbroad diffuse peak near transition temperature along with low dielectric loss\n(< 4%) in a wide temperature range (50-250 oC) found in this material may also\nhave a potential application in high-temperature multilayer capacitors in\nautomotive and aerospace related industries.",
        "positive": "Water dissociation on pristine low-index TiO2 surfaces: Water absorption and dissociation processes on pristine low-index TiO$_2$\ninterfaces are important but poorly understood outside the well-studied anatase\n(101) and rutile (110). To understand these, we construct three sets of machine\nlearning potentials that are simultaneously applicable to various TiO$_2$\nsurfaces, based on three density-functional-theory approximations. We compute\nthe water dissociation free energies on seven pristine TiO$_2$ surfaces, and\npredict that anatase (100), anatase (110), rutile (001), and rutile (011)\nsurfaces favor water dissociation, anatase (101) and rutile (100) surfaces have\nmostly molecular absorption, while the calculated dissociation fraction on\nrutile (110) surface may depend on the density functional assumed. Moreover,\nusing an automated algorithm, we reveal that these surfaces follow different\ntypes of atomistic mechanisms for proton transfer and water dissociation:\none-step, two-step, or both. Our finding thus demonstrates that the different\npristine TiO$_2$ surfaces react with water in distinct ways, and cannot be\nrepresented using just the low-energy anatase (101) and rutile (110) surfaces."
    },
    {
        "anchor": "Impact of Screw and Edge Dislocation on the Thermal Conductivity of\n  Nanowires and Bulk GaN: We report on thermal transport properties of wurtzite GaN in the presence of\ndislocations, by using molecular dynamics simulations. A variety of isolated\ndislocations in a nanowire configuration were analyzed and found to reduce\nconsiderably the thermal conductivity while impacting its temperature\ndependence in a different manner. We demonstrate that isolated screw\ndislocations reduce the thermal conductivity by a factor of two, while the\ninfluence of edge dislocations is less pronounced. The relative reduction of\nthermal conductivity is correlated with the strain energy of each of the five\nstudied types of dislocations and the nature of the bonds around the\ndislocation core. The temperature dependence of the thermal conductivity\nfollows a physical law described by a T$^{-1}$ variation in combination with an\nexponent factor which depends on the material's nature, the type and the\nstructural characteristics of the dislocation's core. Furthermore, the impact\nof the dislocations density on the thermal conductivity of bulk GaN is\nexamined. The variation and even the absolute values of the total thermal\nconductivity as a function of the dislocation density is similar for both types\nof dislocations. The thermal conductivity tensors along the parallel and\nperpendicular directions to the dislocation lines are analyzed. The discrepancy\nof the anisotropy of the thermal conductivity grows in increasing the density\nof dislocations and it is more pronounced for the systems with edge\ndislocations.",
        "positive": "Non-linear Optical Spectroscopy of Excited Exciton States for Efficient\n  Valley Coherence Generation in WSe2 Monolayers: Monolayers (MLs) of MoS2 and WSe2 are 2D semiconductors with strong, direct\noptical transitions that are governed by tightly Coulomb bound eletron-hole\npairs (excitons). The optoelectronic properties of these transition metal\ndichalcogenides are directly related to the inherent crystal inversion symmetry\nbreaking. It allows for efficient second harmonic generation (SHG) and is at\nthe origin of chiral optical selections rules, which enable efficient optical\ninitialization of electrons in specific K-valleys in momentum space. Here we\ndemonstrate how these unique non-linear and linear optical properties can be\ncombined to efficiently prepare exciton valley coherence and polarization\nthrough resonant pumping of an excited exciton state. In particular a new\napproach to coherent alignment of excitons following two-photon excitation is\ndemonstrated. We observe a clear deviation of the excited exciton spectrum from\nthe standard Rydberg series via resonances in SHG spectroscopy and two- and\none-photon absorption. The clear identification of the 2s and 2p exciton\nexcited states combined with first principle calculations including strong\nanti-screening effects allows us to determine an exciton binding energy of the\norder of 600 meV in ML WSe2."
    },
    {
        "anchor": "Optical and Transport Studies of Single Molecule Tunnel junctions based\n  on Self-Assembled Monolayers: We have fabricated a variety of novel molecular tunnel junctions based on\nself-assembled-monolayers (SAM) of two-component solid-state mixtures of\nmolecular wires (1,4 methane benzene-dithiol; Me-BDT with two thiol anchoring\ngroups), and molecular insulator spacers (1-pentanethiol; PT with one thiol\nanchoring group) at different concentration ratios, r of wires/spacers, which\nwere sandwiched between two metallic electrodes such as gold and cobalt. FTIR\nspectroscopy and surface titration were used, respectively to verify the\nformation of covalent bonds with the electrodes, and obtain the number of\nactive molecular wires in the device. The electrical transport properties of\nthe SAM devices were studied as a function of (i) r-value, (ii) temperatures,\nand (iii) different electrodes, via the conductance and differential\nconductance spectra. The measurements were used to analyze the Me-BDT density\nof states near the electrode Fermi level, and the properties of the interface\nbarriers. We measured the Me-BDT single molecule resistance at low bias and\ngold electrodes to be 6x10^9 Ohm. We also determine the energy difference, D\nbetween the Me-BDT HOMO level and the gold Fermi level to be about 1.8 eV. In\naddition we also found that the temperature dependence of the SAM devices with\nr < 10^-4 is much weaker than that of the pure PT device (or r = 0), showing a\nsmall interface barrier.",
        "positive": "Ab initio study of semiconducting carbon nanotubes adsorbed on the\n  Si(100) surface: diameter- and registration-dependent atomic configurations\n  and electronic properties: We present a first-principles study of semiconducting carbon nanotubes\nadsorbed on the unpassivated Si(100) surface. We have found metallicity for the\ncombined system caused by n-doping of the silicon slab representing the surface\nby the SWNT. We confirm this metallicity for nanotubes of different diameters\nand chiral angles, and find the effect to be independent of the orientation of\nthe nanotubes on the surface. We also present adsorption energetics and\nconfigurations which show semiconducting SWNTs farther apart from the surface\nand transferring less charge, in comparison with metallic SWNTs of similar\ndiameter."
    },
    {
        "anchor": "Shift of Infrared Absorption and Emission Spectra of Transition Metal\n  Ions in Solid Solutions of Semiconductor Compounds: A universal theoretical model is proposed that explains the observed shift of\nIR absorption and emission bands in the spectra of transition metal ions in\nsolid solutions of semiconductor compounds. The model has been used for\nestimating the long-wavelength shift of luminescence bands in the spectra of\nsemiconductor solid solutions with increasing concentration in application to\ncrystals of the ternary systems ZnMgSe(Cr2+) and CdMnTe(Fe2+). Description of\nthe phenomenon is generalized to the case of multicomponent solid solutions.",
        "positive": "A novel phase-field based cohesive zone model for modeling interfacial\n  failure in composites: The interface plays a critical role in the mechanical properties of\ncomposites. In the present work, a novel phase-field based cohesive zone model\n(CZM) is proposed for the cracking simulation. The competition and interaction\nbetween the bulk and interfacial cracking are taken into consideration directly\nin both displacement- and phase-field. A modified family of degradation\nfunctions is utilized to describe traction-separation law in the CZM. Finite\nelement implementation of the present CZM was carried out with a completely\nstaggered algorithm. Several numerical examples, including a single bar tension\ntest, a double cantilever beam test, a three-point bending test, and a single\nfiber-reinforced composite test, are carried out to validate the present model\nby comparison with existing numerical and experimental results.The present\nmodel shows its advantage on modeling interaction between bulk and interfacial\ncracking. 1. Introduction"
    },
    {
        "anchor": "The effectiveness of data augmentation in porous substrate, nanowire,\n  fiber and tip images at the level of deep learning intelligence: To prepare for identifying the composition of nanowire-fiber mixtures in\nScanning Electron Microscope (SEM) images, we optimize the performance of image\nclassification between nanowires, fibers and tips due to their geometric\nsimilarities. The SEM images are analyzed by deep learning techniques where the\nvalidation accuracies of 11 convolutional neural network (CNN) models are\ncompared. By increasing the diversity of data such as reflection, translation\nand scale factor approaches, the highest validation accuracy of recognizing\nnanowires, fibers and tips is 97.1%. We proceed to classify the level of\nporosity in anodized aluminum oxide for the self-assisted nanowire growth where\nthe validation accuracy is optimized at 93%. Our software allow scientists to\ncount the percentage of fibers in any nanowire-fiber composite and design the\nporous substrate for embedding different sizes of nanowires automatically,\nwhich assists the software development in Nanoscience Foundries & Fine Analysis\n(NFFA) Europe Projects.",
        "positive": "Confined magnon dispersion in ferromagnetic and antiferromagnetic thin\n  films in a second quantization approach: the case of Fe and NiO: We present a methodology based on the calculation of the inelastic scattering\nfrom magnons via the spin scattering function in confined geometries such as\nthin films using a second quantization formalism, for both ferromagnetic and\nantiferromagnetic materials. The case studies are chosen with an aim to\ndemonstrate the effects of film thickness and crystal orientation on magnon\nmodes, using bcc Fe(100) and NiO with (100) and (111) crystallographic\norientations as prototypical systems. Due to the quantization of the\nquasi-momentum we observe a granularity in the inelastic spectra in the\nreciprocal space path reflecting the orientation of the thin film. This\napproach also allows to capture softer modes that appear due to the partial\ninteraction of magnetic moments close to the surface in a thin film geometry,\nin addition to bulk modes. The softer modes are also affected by\ncrystallographic orientations as illustrated by the different surface-related\npeaks of NiO magnon density of states at approximately ~ 65 meV for (100) and ~\n42 meV for (111). Additionally, we explore the role of anisotropy on magnon\nmodes, revealing that introducing anisotropy to both Fe and NiO films increases\nthe overall hardness of the magnon modes. The introduction of a surface\nanisotropy produces a shift of the surface-related magnon DOS peak to higher\nenergies with increased surface anisotropy, and in some cases leading to\nsurface confined mode."
    },
    {
        "anchor": "Limitations of the two-media approach in calculating magneto-optical\n  properties of layered systems: It is shown that in polar geometry and normal incidence the 2x2 matrix\ntechnique - as discussed in detail in a preceeding paper [Phys. Rev. B 65,\n144448 (2002)] - accounts correctly for multiple reflections and optical\ninterferences, and reduces only in the case of a periodic sequence of identical\nlayers to the Fresnel formula of reflectivity, which in turn is the theoretical\nbasis of the two-media approach, widely used in the literature to compute\nmagneto-optical Kerr spectra. As a numerical example ab-initio calculations of\nthe optical constants for an fcc Pt semi-infinite bulk using the spin-polarized\nrelativistic screened Korringa-Kohn-Rostoker method show very good agreement\nwith experimental data.",
        "positive": "Electrically Detected Magnetic Resonance Modeling and Fitting: An\n  Equivalent Circuit Approach: Continuous-wave electrically detected magnetic resonance (cw-EDMR or just\nEDMR) and its variants are powerful tools to investigate spin-dependent\nprocesses in materials and devices. The use of quadrature detection improves\nthe quality and selectivity of EDMR analysis by allowing, for example, the\nseparation of individual resonant spin lines. Here we propose an equivalent\ncircuit model in order to better understand the EDMR quadrature signal in a\nvariety of different situations. The model considers not just the electrical\nresponse of the sample but of cables and measuring circuit and its influence on\nthe resulting spectral lines. Recent EDMR spectra from Alq3 based OLEDs, as\nwell as from a-Si:H reported in the literature, were successfully described by\nthe model. Moreover, the model allows the implementation of a fitting routine\nthat can be easily used to determine accurate values of crucial parameters such\nas g-factor and linewidth of the resonant lines."
    },
    {
        "anchor": "On the longitudinal spin current induced by a temperature gradient in a\n  ferromagnetic insulator: Based on the solution of the stochastic Landau-Lifshitz-Gilbert equation\ndiscretized for a ferromagnetic chain subject to a uniform temperature\ngradient, we present a detailed numerical study of the spin dynamics with a\nfocus particularly on finite-size effects. We calculate and analyze the net\nlongitudinal spin current for various temperature gradients, chain lengths, and\nexternal static magnetic fields. In addition, we model an interface formed by a\nnonuniformly magnetized finite-size ferromagnetic insulator and a normal metal\nand inspect the effects of enhanced Gilbert damping on the formation of the\nspace-dependent spin current within the chain. A particular aim of this study\nis the inspection of the spin Seebeck effect beyond the linear response regime.\nWe find that within our model the microscopic mechanism of the spin Seebeck\ncurrent is the magnon accumulation effect quantified in terms of the exchange\nspin torque. According to our results, this effect drives the spin Seebeck\ncurrent even in the absence of a deviation between the magnon and phonon\ntemperature profiles. Our theoretical findings are in line with the recently\nobserved experimental results by M. Agrawal et al., Phys. Rev. Lett. 111,\n107204 (2013).",
        "positive": "Magnetism and magnetocaloric properties of Co$_{1-x}$Mn$_x$Cr$_2$O$_4$: Co$_{1-x}$Mn$_x$Cr$_2$O$_4$ crystallizes as a normal spinel in the cubic $Fd\n\\overline{3}m$ space group, and the end members have been reported to display a\nregion of collinear ferrimagnetism as well as a low-temperature spin-spiral\nstate with variable coherence lengths from 3 nm to 10 nm in polycrystalline\nsamples. Here, we present the synthesis of the entire solid solution, and data\nshowing that the ferrimagnetic ordering temperature as well as the spin-spiral\nlock-in temperature are tunable with the Co/Mn ratio. The peak magnetocaloric\nentropy change was determined to be $\\Delta S_M$ = -5.63 J kg$^{-1}$ K$^{-1}$\nin an applied magnetic field change of $\\Delta H$ = 0 T to 5 T for the Mn\nend-member at the ferrimagnetic ordering temperature. Using density functional\ntheory (DFT), we explore the shortcomings of the magnetic deformation proxy to\nidentify trends in $\\Delta S_M$ across composition in this spinel system, and\nexplore future extensions of theory to address these discrepancies."
    },
    {
        "anchor": "Recurrent neural networks and transfer learning for elasto-plasticity in\n  woven composites: As a surrogate for computationally intensive meso-scale simulation of woven\ncomposites, this article presents Recurrent Neural Network (RNN) models.\nLeveraging the power of transfer learning, the initialization challenges and\nsparse data issues inherent in cyclic shear strain loads are addressed in the\nRNN models. A mean-field model generates a comprehensive data set representing\nelasto-plastic behavior. In simulations, arbitrary six-dimensional strain\nhistories are used to predict stresses under random walking as the source task\nand cyclic loading conditions as the target task. Incorporating sub-scale\nproperties enhances RNN versatility. In order to achieve accurate predictions,\nthe model uses a grid search method to tune network architecture and\nhyper-parameter configurations. The results of this study demonstrate that\ntransfer learning can be used to effectively adapt the RNN to varying strain\nconditions, which establishes its potential as a useful tool for modeling\npath-dependent responses in woven composites.",
        "positive": "VI3: a 2D Ising ferromagnet: Two-dimensional (2D) magnetic materials are of great current interest for\ntheir promising applications in spintronics. Here we propose the van der Waals\n(vdW) material VI3 to be a 2D Ising ferromagnet (FM), using density functional\ncalculations, crystal field level diagrams, superexchange model analyses, and\nMonte Carlo simulations. The $a_{1g}$$^1$$e'_{-}$$^1$ ground state in the\ntrigonal crystal field gives rise to the 2D Ising FM due to a significant\nsingle ion anisotropy (SIA) and enhanced FM superexchange both associated with\nthe $S_z$=1 and $L_z$=--1 state of V3+ ions. We find that a tensile strain on\nthe VI3 monolayer further stabilizes the $a_{1g}$$^1$$e'_{-}$$^1$ ground state,\nand its Curie temperature ($T_{\\rm C}$) would increase from 70 K to 90-110 K\nunder a 2.5-5\\% tensile strain. Moreover, we suggest a group of spin-orbital\nstates with a strong SIA which may help to search more 2D Ising magnets."
    },
    {
        "anchor": "Carbon-based nanostructured composite films: elastic, mechanical and\n  optoelectronic properties derived from computer simulations: In this review, we present our recent computational work on carbon-based\nnanostructured composites. These materials consist of carbon crystallites\nembedded in an amorphous carbon matrix and are modeled here through classical\nand semi-empirical quantum-mechanical simulations. We investigate the\nenergetics, mechano-elastic, and optoelectronic properties of these materials.\nOnce the stability of the composites is discussed, we move on to the\ncalculation of their elastic moduli and constants, their anisotropy and elastic\nrecovery. At a next step, we focus on diamond composites, which were found to\nbe the most stable among the composites studied, and went beyond the elastic\nregime to investigate their ideal fracture. Finally, for these materials, the\nelectronic density of states, dielectric function, and optical response were\ncalculated and linked to the disorder in the structures. Our findings unveil\nthe high potential of these materials in nanotechnological applications,\nespecially as ultlra-hard coatings.",
        "positive": "Thermal and electrical cross-plane conductivity at the nanoscale in\n  poly(3,4-ethylenedioxythiophene):trifuoromethanesulfonate thin films: Cross-plane electrical and thermal transport in thin films of a conducting\npolymer (poly(3,4-ethylenedioxythiophene), PEDOT) stabilized with\ntrifluoromethanesulfonate (OTf) is investigated in this study. We explore their\nelectrical properties by conductive atomic force microscopy (C-AFM), which\nreveals the presence of highly conductive nano-domains. Thermal conductivity in\ncross-plane direction is measured with Null-Point scanning thermal microscopy\n(NP-SThM): PEDOT:OTf indeed demonstrates non-negligible electronic contribution\nto the thermal transport. We further investigate the correlation between\nelectrical and thermal conductivity by applying posttreatment: chemical\nreduction (de-doping) for the purpose of lowering charge carrier concentration\nand hence, electrical conductivity and acid treatment (over-doping) to increase\nthe latter. From our measurements, we find a vibrational thermal conductivity\nof 0.34 (+/- 0.04) Wm-1 K-1. From the linear dependence or the electronic\ncontribution of thermal conductivity vs. the electronic conductivity\n(Widemann-Franz law), we infer a Lorenz number 6 times larger than the\nclassical Sommerfeld value as also observed in many organic materials for\nin-plane thermal transport. Applying the recently proposed molecular\nWidemann-Franz law, we deduced a reorganization energy of 0.53 (+/- 0.06) eV."
    },
    {
        "anchor": "Surface X-ray Speckles: Coherent Surface Diffraction from Au (0 0 1): We present coherent speckled x-ray diffraction patterns obtained from a\nmonolayer of surface atoms. We measured both the specular anti-Bragg reflection\nand the off-specular hexagonal reconstruction peak for the Au (0 0 1) surface\nreconstruction. We observed fluctuations of the speckle patterns even when the\nintegrated intensity appears static. By auto-correlating the speckle patterns,\nwe were able to identify two qualitatively different surface dynamic behaviors\nof the hex reconstruction depending on the sample temperature.",
        "positive": "Barocaloric and Magnetocaloric Effects in Fe49Rh51: We report on calorimetry under applied hydrostatic pressure and magnetic\nfield at the antiferromagnetic (AFM)-ferromagnetic (FM) transition of\nFe$_{49}$Rh$_{51}$. Results demonstrate the existence of a giant barocaloric\neffect in this alloy, a new functional property that adds to the magnetocaloric\nand elastocaloric effects previously reported for this alloy. All caloric\neffects originate from the AFM/FM transition which encompasses changes in\nvolume, magnetization and entropy. The strong sensitivity of the transition\ntemperatures to both hydrostatic pressure and magnetic field confers to this\nalloy outstanding values for the barocaloric and magnetocaloric strengths\n($|\\Delta S|$/$\\Delta p$ $\\sim$ 12 J kg$^{-1}$ K $^{-1}$ kbar$^{-1}$ and\n$|\\Delta S|$/$\\mu_0\\Delta H$ $\\sim$ 12 J kg$^{-1}$ K$^{-1}$ T$^{-1}$). Both\nbarocaloric and magnetocaloric effects have been found to be reproducible upon\npressure and magnetic field cycling. Such a good reproducibility and the large\ncaloric strengths make Fe-Rh alloys particularly appealing for solid-state\ncooling technologies at weak external stimuli."
    },
    {
        "anchor": "Kinetic mechanism for reversible structural transition in MoTe2 induced\n  by excess charge carriers: Kinetic of a reversible structural transition between insulating (2H) and\nmetallic (1T') phases in a monolayer MoTe2 due to an electrostatic doping is\nstudied using first-principle calculations. The driving force for the\nstructural transition is the energy gained by transferring excess electrons\nfrom the bottom of the conduction band to lower energy gapless states in the\nmetallic phase as have been noticed in earlier studies. The corresponding\nstructural transformation involves dissociation of Mo-Te bonds (one per formula\nunit), which results in a kinetic energy barrier of 0.83 eV. The transformation\ninvolves a consecutive movement of atoms similar to a domain wall motion. The\npresence of excess charge carriers modifies not only the total energy of the\ninitial and final states, but also lowers an energy of the transition state. An\nexperimentally observed hysteresis in the switching process can be attributed\nto changes in the kinetic energy barrier due to its dependence on the excess\ncarrier density.",
        "positive": "Solute softening and vacancy generation by diffusion-less climb in\n  magnesium alloys: Active room temperature diffusion-less climb of the <a> edge dislocations in\nmodel Mg-Al alloys was observed using molecular dynamics simulations.\nDislocations on prismatic and pyramidal I planes climb through the basal plane\nto overcome solute obstacles. This out-of-plane dislocation motion softens the\nhigh resistance pyramidal I glide and significantly reduces the anisotropy of\ndislocation mobility, and could help improve the ductility of Mg. The flow\nstress scales linearly with solute concentration, cAl. Dislocations climb\npredominantly in the negative direction, with climb angle on the order of\n0.01cAl, producing very high vacancy concentration on the order of 10-4."
    },
    {
        "anchor": "Sub-ps thermionic electron injection effects on exciton-formation\n  dynamics at a van der Waals semiconductor/metal interface: Inorganic van der Waals bonded semiconductors like transition metal\ndichalcogenides are subject of intense research due to their electronic and\noptical properties which are promising for next-generation optoelectronic\ndevices. In this context, understanding the ultrafast carrier dynamics, as well\nas charge and energy transfer at the interface between metals and\nsemiconductors is crucial and yet quite unexplored. Here, we present an\nexperimental study on how thermally induced ultrafast charge carrier injection\naffects the exciton formation dynamics in bulk WS2 by employing a\npump-push-probe scheme, where a pump pulse induces thermionic injection of\nelectrons from the gold substrate into the conduction band of the\nsemiconductor, and another delayed push pulse excites direct transitions in the\nWS2. The transient response shows different dynamics on the sub-ps timescale by\nvarying the delay between pump and push pulses or by changing the pump fluence,\nthus disclosing the important role of ultrafast hot electron injection on the\nexciton formation dynamics. Our findings might have potential impact on\nresearch fields that target the integration of ultrafast optics at the boundary\nof photonics and electronics, as well as in optically-driven CMOS and quantum\ntechnologies.",
        "positive": "Tuning 2D hyperbolic plasmons in black phosphorus: Black phosphorus presents a very anisotropic crystal structure, making it a\npotential candidate for hyperbolic plasmonics, characterized by a permittivity\ntensor where one of the principal components is metallic and the other\ndielectric. Here we demonstrate that atomically thin black phosphorus can be\nengineered to be a hyperbolic material operating in a broad range of the\nelectromagnetic spectrum from the entire visible spectrum to ultraviolet. With\nthe introduction of an optical gain, a new hyperbolic region emerges in the\ninfrared. The character of this hyperbolic plasmon depends on the interplay\nbetween gain and loss along the two crystalline directions."
    },
    {
        "anchor": "Nonlinear background corrections to dielectric permittivity of ferroics\n  and multiferroics: Temperature measurements of dielectric permittivity are performed for\nnonstoichiometric ferroelectric lead germanate Pb$_{4.95}$Ge$_3$O$_{11}$ and\nmultiferroic solid solution [N(C$_2$H$_5$)$_4$]$_2$CoClBr$_3$. Unlike the heat\ncapacity data, the analysis of the dielectric permittivity of ferroics is\nusually performed at the assumption that the dielectric \"background\" is\nnegligible compared with its critical part. In this work we quantitatively\ninterpret the dielectric properties of the single crystals mentioned above and\nthe appropriate literature data for multiferroic Sr$_2$IrO$_4$ crystals, using\ngeneralized Curie-Weiss formulas that combine corrections due to a nonlinear\ntemperature-dependent dielectric background, a modified critical index of\nelectric susceptibility, and a diffuse character of phase transition. We argue\nthat taking account of the temperature dependent dielectric background can\nimprove notably the quantitative analysis of PTs for a number of classes of the\nferroic materials.",
        "positive": "Large antiferromagnetic fluctuation enhancement of the thermopower at a\n  critical doping in magnetic semimetal Cr1+dTe2: Cr1+dTe2 is a self-intercalated transition metal dichalcogenide that hosts\ntunable electronic filling and magnetism in its semimetallic band structure.\nRecent angle-resolved photoemission spectroscopy (ARPES) studies have unveiled\na systematic shift in this semimetallic band structure relative to the chemical\npotential with increased Cr doping. This report presents the temperature and\nmagnetic field dependence of the longitudinal thermopower Sxx for different\nCr1+dTe2 compositions. We show that as doping increases, the sign of Sxx\nchanges from positive to negative at the critical doping level of d ~ 0.5. This\nobserved doping-dependent trend in the thermopower is consistent with the\nevolution of the semimetallic band structure from ARPES. Importantly, an\nanomalous enhancement of the thermoelectric response is also observed around\nd~0.5. Combining information from magnetometry and ARPES measurements,\nexistence of the critical nature of the doping level dc (~0.5) is unveiled in\nmagnetic semimetal Cr1+dTe2, where antiferromagnetic fluctuation and\nnear-Fermi-energy pseudogap formation play a potential vital role in enhancing\nthermoelectric energy conversion."
    },
    {
        "anchor": "Bipolar electrocaloric effect in Pb1-xGdx(Mg1+x/3Nb2-x/3)O3 ceramic:\n  relaxor with super-dipolar glass state: The electrocaloric (EC) effect is calculated for Gd-substituted PMN (x = 0 to\n0.1) relaxors from temperature dependent heat capacity and polarization\nmeasurements, using a thermodynamic Maxwell equation. Polarization change with\ntemperature reveals an anomalous behaviour around the glass transition\ntemperature, which is in the vicinity of a crossover from positive to negative\nEC effect, which is explained evoking the critical slowing-down of the polar\nnano-domains dynamics to super-dipolar glass state upon cooling. The maximum\nnegative EC coefficient is observed to decrease from 0.4 K-mm/kV at 164 K to\n0.1 K-mm/kV with x.",
        "positive": "Nano-Clustering Mediates Phase Transitions in a\n  Diastereomerically-Stabilized Ferroelectric Nematic System: During the last half-decade, a new class of ferroic-fluid, ferroelectric\nnematic liquid crystals (NFLCs), creates a noise owing to its exceptional\nproperties such as a colossal polarization, high electro-optic activity plus\nhigh fluidity. Regardless of recent huge efforts on design and development of\nnew NFLC molecules based on molecular parameters, the control of NF phase\ntransitions and the stabilization of NF phase are still challenging. Here we\ndiscuss the impact of mixing of DIO diastereomer [transDIO (1) and cisDIO (2)]\nto the NF phase transition, in terms of the smectic cybotactic cluster\nformation examined by X-ray diffraction. Interestingly, the result suggests\nthat smooth exchange of NFLC 1 by non-LC 2 both with similar dipole and\nmolecular backbone plays a role in the alteration of the NF phase transition."
    },
    {
        "anchor": "Real-space study of the optical absorption in alternative phases of\n  silicon: We introduce a real-space approach to understand the relationship between\noptical absorption and crystal structure. We apply this approach to alternative\nphases of silicon, with a focus on the Si$_{20}$ crystal phase as a case study.\nWe find that about 83% of the changes in the calculated low-energy absorption\nin Si$_{20}$ as compared to Si in the diamond structure can be attributed to\nreducing the differences between the on-site energies of the bonding and\nanti-bonding orbitals as well as increasing the hopping integrals for specific\nSi-Si bonds.",
        "positive": "Low temperature synthesis of heterostructures of transition metal\n  dichalcogenide alloys (WxMo1-xS2) and graphene with superior catalytic\n  performance for hydrogen evolution: Large-area ($\\sim$cm$^2$) films of vertical heterostructures formed by\nalternating graphene and transition-metal dichalcogenide(TMD) alloys are\nobtained by wet chemical routes followed by a thermal treatment at low\ntemperature (300 $^\\circ$C). In particular, we synthesized stacked graphene and\nW$_x$Mo$_{1-x}$S$_2$ alloy phases that were used as hydrogen evolution\ncatalysts. We observed a Tafel slope of 38.7 mV dec$^{-1}$ and 96 mV onset\npotential (at current density of 10 mA cm$^{-2}$) when the heterostructure\nalloy is annealed at 300 $^o$C. These results indicate that heterostructure\nformed by graphene and W$_{0.4}$Mo$_{0.6}$S$_2$ alloys are far more efficient\nthan WS$_2$ and MoS$_2$ by at least a factor of two, and it is superior than\nany other reported TMD system. This strategy offers a cheap and low temperature\nsynthesis alternative able to replace Pt in the hydrogen evolution reaction\n(HER). Furthermore, the catalytic activity of the alloy is stable over time,\ni.e. the catalytic activity does not experience a significant change even after\n1000 cycles. Using density functional theory calculations, we found that this\nenhanced hydrogen evolution in the W$_x$Mo$_{1-x}$S$_2$ alloys is mainly due to\nthe lower energy barrier created by a favorable overlap of the d-orbitals from\nthe transition metals and the s-orbitals of H$_2$, with the lowest energy\nbarrier occurring for W$_{0.4}$Mo$_{0.6}$S$_2$ alloy. Thus, it is now possible\nto further improve the performance of the \"inert\" TMD basal plane via metal\nalloying, in addition to the previously reported strategies of creation of\npoint defects, vacancies and edges. The synthesis of\ngraphene/W$_{0.4}$Mo$_{0.6}$S$_2$ produced at relatively low temperatures is\nscalable and could be used as an effective low cost Pt-free catalyst."
    },
    {
        "anchor": "Electronic Properties, Screening and Efficient Carrier Transport in\n  NaSbS2: NaSbS2 is a semiconductor that was recently shown to have remarkable efficacy\nas a solar absorber indicating efficient charge collection even in defected\nmaterial. We report first principles calculations of properties that show (1)\nan indirect gap only slightly smaller than the direct gap, which may impede\nrecombination of photoexcited carriers, (2) highly anisotropic electronic and\noptical properties reflecting a layered crystal structure, (3) a pushed up\nvalence band maximum due to repulsion from the Sb 5s states and (4) cross-gap\nhybridization between the S p derived valence bands and the Sb 5p states. This\nlatter feature leads to enhanced Born effective charges that can provide local\nscreening and therefore defect tolerance. These features are discussed in\nrelation to the performance of the compound as a semiconductor with efficient\ncharge collection.",
        "positive": "A Versatile Post-Doping Towards Two-Dimensional Semiconductors: We have developed a simple and straightforward way to realize controlled\npost-doping towards 2D transition metal dichalcogenides (TMDs). The key idea is\nto use low-kinetic energy dopant beams and a high-flux chalcogen beam at the\nsame time, leading to substitutional doping with controlled dopant densities.\nAtomic-resolution transmission electron microscopy has revealed that dopant\natoms injected toward TMDs are incorporated substitutionally into the hexagonal\nframework of TMDs. Electronic properties of doped TMDs (Nb-doped WSe2) have\nshown drastic change, p-type action with more than two orders of magnitude\nincrease in on current. Position-selective doping has also been demonstrated by\nthe post-doping toward TMDs with a patterned mask on the surface. The\npost-doping method developed in this work can be a versatile tool for 2D-based\nnext-generation electronics in the future."
    },
    {
        "anchor": "Atomistic Mechanism Underlying the Si(111)-(7\\times7) Surface\n  Reconstruction Revealed by Artificial Neural-network Potential: The 7\\times7 reconstruction of the Si(111) surface represents arguably the\nmost fascinating surface reconstruction so far observed in nature. Yet, the\natomistic mechanism underpinning its formation remains unclear after it was\ndiscovered sixty years ago. Experimentally, it is observed post priori so that\nanalysis of its formation mechanism can only be carried out in analogy with\narchaeology. Theoretically, density-functional-theory (DFT) correctly predicts\nthe Si(111)-(7\\times7) ground state but is impractical to simulate its\nformation process; while empirical potentials failed to produce it as the\nground state. Developing an artificial neural-network potential of DFT quality,\nwe carried out accurate large-scale simulations to unravel the formation of the\nSi(111)-(7\\times7) surface. We reveal a possible step-mediated atom-pop\nrate-limiting process that triggers massive non-conserved atomic\nrearrangements, most remarkably, a critical process of collective vacancy\ndiffusion that mediates a sequence of selective dimer, corner-hole, stacking\nfault and dimer-line pattern formation, to fulfill the 7\\times7 reconstruction.\nOur findings may not only solve the long-standing mystery of this famous\nsurface reconstruction but also illustrate the power of machine learning in\nstudying complex structures.",
        "positive": "Charge and spin transport in a metal-semiconductor heterostructure with\n  double Schottky barriers: Taking into account the available experimental results, we model the\nelectronic properties and current-voltage characteristics of a\nferromagnet-semiconductor junction. The Fe/GaAs interface is considered as a\nFe/(i-GaAs)/n+-GaAs/n-GaAs multilayer structure with the Schottky barrier. We\nalso calculate numerically the current-voltage characteristics of a\ndouble-Schottky-barrier structure Fe/GaAs/Fe, which are in agreement with\navailable experimental data. For this structure, we have estimated the spin\ncurrent in the GaAs layer, which characterizes spin injection from the\nferromagnet to the semiconductor."
    },
    {
        "anchor": "Derivation of a governing rule in triboelectric charging and series from\n  thermoelectricity: Friction-driven static electrification is familiar and fundamental in daily\nlife, industry, and technology, but its basics have long been unknown and have\ncontinually perplexed scientists from ancient Greece to the modern high-tech\nera. Despite its simple manifestation, triboelectric charging is believed to be\nvery complex because of the unresolvable interfacial interaction between two\nrubbing materials. Here, we for the first time reveal a simple physics of\ntriboelectric charging and triboelectric series based on friction-originated\nthermoelectric charging effects at the interface, characterized by the material\ndensity (${\\rho}$), specific heat (c), thermal conductivity (k), and Seebeck\ncoefficient (S) of each material. We demonstrate that energy dissipational heat\nat the interface induces temperature variations in the materials and thus\ndevelops electrostatic potentials that will initiate thermoelectric charging\nacross the interface. We find that the trends and quantities of triboelectric\ncharging for various polymers, metals, semiconductors, and even lightning\nclouds are simply governed by the triboelectric factor\n${\\xi}=S/\\sqrt{{\\rho}ck}$. The triboelectric figure-of-merit is expressed with\nthe triboelectric power K=${\\xi}\\sqrt{t/{\\pi}}$, of which the difference can be\nmaximized up to 1.2 V/W cm$^{-2}$ at the friction time t = 1 s. Our findings\nwill bring significant opportunities for microscopic understanding and\nmanagement of triboelectricity or static electrification.",
        "positive": "Energy-resolved electron-spin dynamics at surfaces of p-doped GaAs: Electron-spin relaxation at different surfaces of p-doped GaAs is\ninvestigated by means of spin, time and energy resolved 2-photon photoemission.\nThese results are contrasted with bulk results obtained by time-resolved\nFaraday rotation measurements as well as calculations of the Bir-Aronov-Pikus\nspin-flip mechanism. Due to the reduced hole density in the band bending region\nat the (100) surface the spin-relaxation time increases over two orders of\nmagnitude towards lower energies. At the flat-band (011) surface a constant\nspin relaxation time in agreement with our measurements and calculations for\nbulk GaAs is obtained."
    },
    {
        "anchor": "Emergent electromagnetism in solids: Electromagnetic field (EMF) is the most fundamental field in condensed-matter\nphysics. Interaction between electrons, electron-ion interaction, and ion-ion\ninteraction are all of the electromagnetic origin, while the other 3\nfundamental forces, i.e., gravitational force, weak and strong interactions are\nirrelevant in the energy/length scales of condensed-matter physics. Also the\nphysical properties of condensed-matters such as transport, optical, magnetic\nand dielectric properties, are almost described as their electromagnetic\nresponses. In addition to this EMF in the low energy sector, it often happens\nthat the gauge fields appear as the emergent phenomenon due to the projection\nof the electronic wavefunctions onto the curved manifold of the Hilbert\nsub-space. These emergent electromagnetic fields (EEMF's) play important roles\nin many places in condensed-matter physics including the quantum Hall effect,\nstrongly correlated electrons, and also in non-interacting electron systems. In\nthis article, we describe its fundamental idea and some of the applications\nrecently studied.",
        "positive": "Non-uniform sampling schemes of the Brillouin zone for many-electron\n  perturbation-theory calculations in reduced dimensionality: First principles calculations based on many-electron perturbation theory\nmethods, such as the \\textit{ab initio} GW and GW plus Bethe-Salpeter equation\n(GW-BSE) approach, are reliable ways to predict quasiparticle and optical\nproperties of materials, respectively. However, these methods involve more care\nin treating the electron-electron interaction and are considerably more\ncomputationally demanding when applied to systems with reduced dimensionality,\nsince the electronic confinement leads a slower convergence of sums over the\nBrillouin zone due to a much more complicated screening environment that\nmanifests in the \"head\" and \"neck\" elements of the dielectric matrix. Here, we\npresent two new schemes to sample the Brillouin zone for GW and GW-BSE\ncalculations: the non-uniform neck subsampling method and the clustered\nsampling interpolation method, which can respectively be used for a family of\nsingle-particle problems, such as GW calculations, and for problems involving\nthe scattering of two-particle states, such as when solving the BSE. We tested\nthese methods on several few-layer semiconductors and graphene and show that\nthey perform a much more efficient sampling of the Brillouin zone and yield two\nto three orders of magnitude reduction in the computer time. These two methods\ncan be readily incorporated into several \\textit{ab initio} packages that\ncompute electronic and optical properties through the GW and GW-BSE approaches."
    },
    {
        "anchor": "Dislocation networks in helium-4 crystals: The mechanical behavior of crystals is dominated by dislocation networks,\ntheir structure and their interactions with impurities or thermal phonons.\nHowever, in classical crystals, networks are usually random with impurities\noften forming non-equilibrium clusters when their motion freezes at low\ntemperature. Helium provides unique advantages for the study of dislocations:\ncrystals are free of all but isotopic impurities, the concentration of these\ncan be reduced to the ppb level, and the impurities are mobile at all\ntemperatures and therefore remain in equilibrium with the dislocations. We have\nachieved a comprehensive study of the mechanical response of 4He crystals to a\ndriving strain as a function of temperature, frequency and strain amplitude.\nThe quality of our fits to the complete set of data strongly supports our\nassumption of string-like vibrating dislocations. It leads to a precise\ndetermination of the distribution of dislocation network lengths and to\ndetailed information about the interaction between dislocations and both\nthermal phonons and 3He impurities. The width of the dissipation peak\nassociated with impurity binding is larger than predicted by a simple Debye\nmodel, and much of this broadening is due to the distribution of network\nlengths.",
        "positive": "Theory of Rabi interaction between an infrared-active phonon and\n  cavity-resonant modes: We present the theory of interaction between a polar vibration in a\nsemiconductor and an electromagnetic mode of a surrounding cavity. Tuning the\ncavity frequency near the transverse optical phonon frequency couples the\nphonon-induced polarization field within the dielectric and the electromagnetic\nfield in the cavity. Depending on engineering parameters, we predict that this\ncavity quantum electrodynamic interaction may reach the strong coupling regime.\nThe resonances of the system are in the terahertz spectral region, and while\nspectroscopic measurements are a possible route for the detection of such a\nsystem, we emphasize the possibility of measuring the Rabi oscillation directly\nin the time domain with femtosecond optical pulses."
    },
    {
        "anchor": "Fluctuations and Dissipation of Coherent Magnetization: A quantum mechanical model is used to derive a generalized Landau-Lifshitz\nequation for a magnetic moment, including fluctuations and dissipation. The\nmodel reproduces the Gilbert-Brown form of the equation in the classical limit.\nThe magnetic moment is linearly coupled to a reservoir of bosonic degrees of\nfreedom. Use of generalized coherent states makes the semiclassical limit more\ntransparent within a path-integral formulation. A general\nfluctuation-dissipation theorem is derived. The magnitude of the magnetic\nmoment also fluctuates beyond the Gaussian approximation. We discuss how the\napproximate stochastic description of the thermal field follows from our\nresult. As an example, we go beyond the linear-response method and show how the\nthermal fluctuations become anisotropy-dependent even in the uniaxial case.",
        "positive": "General Microscopic Model of Magnetoelastic Coupling from\n  First-Principles: Magnetoelastic coupling, i.e., the change of crystal lattice induced by a\nspin order, is not only scientifically interesting, but also technically\nimportant. In this work, we propose a general microscopic model from\nfirst-principles calculations to describe the magnetoelastic coupling and\nprovide a way to construct the microscopic model from density functional theory\ncalculations. Based on this model, we reveal that there exists a previously\nunexpected contribution to the electric polarization induced by the spin-order\nin multiferroics due to the combined effects of magnetoelastic coupling and\npiezoelectric effect. Interestingly and surprisingly, we find that this lattice\ndeformation contribution to the polarization is even larger than that from the\npure electronic and ion-displacement contributions in BiFeO3. This model of\nmagnetoelastic coupling can be generally applied to investigate the other\nmagnetoelastic phenomena."
    },
    {
        "anchor": "Prediction of local elasto-plastic stress and strain fields in a\n  two-phase composite microstructure using a deep convolutional neural network: Design and analysis of inelastic materials requires prediction of physical\nresponses that evolve under loading. Numerical simulation of such behavior\nusing finite element (FE) approaches can call for significant time and\ncomputational effort. To address this challenge, this paper demonstrates a deep\nlearning (DL) framework that is capable of predicting micro-scale\nelasto-plastic strains and stresses in a two-phase medium, at a much greater\nspeed than traditional FE simulations. The proposed framework uses a deep\nconvolutional neural network (CNN), specifically a U-Net architecture with 3D\noperations, to map the composite microstructure to the corresponding stress and\nstrain fields under a predetermined load path. In particular, the model is\napplied to a two-phase fiber reinforced plastic (FRP) composite microstructure\nsubjected to a given loading-unloading path, predicting the corresponding\nstress and strain fields at discrete intermediate load steps. A novel two-step\ntraining approach provides more accurate predictions of stress, by first\ntraining the model to predict strain fields and then using those strain fields\nas input to the model that predicts the stress fields. This efficient\ndata-driven approach enables accurate prediction of physical fields in\ninelastic materials, based solely on microstructure images and loading\ninformation.",
        "positive": "An extreme value statistics model of heterogeneous ice nucleation for\n  quantifying the stability of supercooled aqueous systems: The propensity of water to remain in a metastable liquid state at\ntemperatures below its equilibrium melting point holds significant potential\nfor cryopreserving biological material such as tissues and organs. The benefits\nconferred are a direct result of progressively reducing metabolic expenditure\ndue to colder temperatures while simultaneously avoiding the irreversible\ndamage caused by the crystallization of ice. Unfortunately, the freezing of\nwater in bulk systems of clinical relevance is dominated by random\nheterogeneous nucleation initiated by uncharacterized trace impurities, and the\nmarked unpredictability of this behavior has prevented implementation of\nsupercooling outside of controlled laboratory settings and in volumes larger\nthan a few milliliters. Here, we develop a statistical model that jointly\ncaptures both the inherent stochastic nature of nucleation using conventional\nPoisson statistics as well as the random variability of heterogeneous\nnucleation catalysis through bivariate extreme value statistics. Individually,\nthese two classes of models cannot account for both the time-dependent nature\nof nucleation and the sample-to-sample variability associated with\nheterogeneous catalysis, and traditional extreme value models have only\nconsidered variation of the characteristic nucleation temperature. We conduct a\nseries of constant cooling rate and isothermal nucleation experiments with\nphysiological saline solutions and leverage the statistical model to evaluate\nthe natural variability of kinetic and thermodynamic nucleation parameters. By\nquantifying freezing probability as a function of temperature, supercooled\nduration, and system volume, while accounting for nucleation site variability,\nthis study also provides a basis for the rational design of stable supercooled\nbiopreservation protocols."
    },
    {
        "anchor": "Vibrational Modes and Terahertz Physical Phenomena Underpinning ZIF-71\n  Metal-Organic Framework: The zeolitic imidazole framework ZIF-71 has the potential to outperform other\nwell-studied metal-organic frameworks due to its intrinsic hydrophobicity and\nlarge pore size. However, a detailed description of its complex physical\nphenomena and structural dynamics has been lacking thus far. Herein, we\nelucidated all vibrational modes of ZIF-71 using high-resolution inelastic\nneutron scattering and synchrotron radiation infrared spectroscopy in\nconjunction with density functional theory calculations. We discover low-energy\ncollective modes, such as gate-opening and shearing mechanisms that may affect\nthe functions and framework stability of ZIF-71. Its single-crystal mechanical\nproperties are further unraveled by nanoscale analytics.",
        "positive": "Jahn-Teller like origin of the tetragonal distortion in disordered Fe-Pd\n  magnetic shape memory alloys: The electronic structure and magnetic properties of disordered\nFe$_{x}$Pd$_{100-x}$ alloys $(50 < x < 85)$ are investigated in the framework\nof density functional theory using the full potential local orbital method\n(FPLO). Disorder is treated in the coherent potential approximation (CPA). Our\ncalculations explain the experimental magnetization data. The origin of the\ntetragonal distortion in the Fe-Pd magnetic shape memory alloys is found to be\na Jahn-Teller like effect which allows the system to reduce its band energy in\na narrow composition range. Prospects for an optimization of the alloys'\nproperties by adding third elements are discussed."
    },
    {
        "anchor": "Atomic-scale observations of electrical and mechanical manipulation of\n  topological polar flux-closure: The ability to controllably manipulate the complex topological polar\nconfigurations, such as polar flux-closure via external stimuli, enables many\napplications in electromechanical devices and nanoelectronics including\nhigh-density information storage. Here, by using the atomically resolved in\nsitu scanning transmission electron microscopy, we find that a polar\nflux-closure structure in PbTiO3/SrTiO3 superlattices films can be reversibly\nswitched to ordinary mono ferroelectric c domain or a domain under electric\nfield or stress. Specifically, the electric field initially drives the\nflux-closure move and breaks them to form intermediate a/c striped domains,\nwhile the mechanical stress firstly starts to squeeze the flux-closures to\nconvert into small vortices at the interface and form a continues dipole wave.\nAfter the removal of the external stimuli, the flux-closure structure\nspontaneously returns. Our atomic study provides valuable insights into\nunderstanding the lattice-charge interactions and the competing interactions\nbalance in these complex topological structures. Such reversible switching\nbetween the flux-closure and ordinary ferroelectric domains also provides the\nfoundation for applications such as memories and sensors.",
        "positive": "Magnetotransport properties of (Ga,Mn)As investigated at low temperature\n  and high magnetic field: Magnetotransport properties of ferromagnetic semiconductor (Ga,Mn)As have\nbeen investigated. Measurements at low temperature (50 mK) and high magnetic\nfield (<= 27 T) have been employed in order to determine the hole concentration\np = 3.5x10^20 cm ^-3 of a metallic (Ga0.947Mn0.053)As layer. The analysis of\nthe temperature and magnetic field dependencies of the resistivity in the\nparamagnetic region was performed with the use of the above value of p, which\ngave the magnitude of p-d exchange energy |N0beta | ~ 1.5 eV."
    },
    {
        "anchor": "Barkhausen effect in the first order structural phase transition in\n  type-II Weyl semimetal MoTe2: We report the first observation of the non-magnetic Barkhausen effect in van\nder Waals layered crystals, specifically, between the Td and 1T' phases in\ntype-II Weyl semimetal MoTe2. Thinning down the MoTe2 crystal from bulk\nmaterial to about 25nm results in a drastic strengthening of the hysteresis in\nthe phase transition, with the difference in critical temperature increasing\nfrom 40K to more than 300K. The Barkhausen effect appears for thin samples and\nthe temperature range of the Barkhausen zone grows approximately linearly with\nreducing sample thickness, pointing to a surface origin of the phase pinning\ndefects. The distribution of the Barkhausen jumps shows a power law behavior,\nwith its critical exponent {\\alpha} = 1.27, in good agreement with existing\nscaling theory. Temperature-dependent Raman spectroscopy on MoTe2 crystals of\nvarious thicknesses shows results consistent with our transport measurements.",
        "positive": "beta phase manganese dioxide nanorods Synthesis and characterization for\n  supercapacitor applications: Manganese dioxide nanorods were synthesized using novel solution route. The\nphase and microstructure of synthesized materials were identified using X ray\ndiffraction, scanning electron and transmission electron microscopic\nmeasurements. The material crystallizes into beta crystallographic phase and\nconsists of nanorods of diameter in the range of about 10-14 nm and length\nabout 50 nm. The Fourier Transform Infrared (FTIR) spectroscopic and\nthermogravimetric analysis (TGA) measurements were carried out to understand\nthe materials microscopic and thermal properties. The material exhibits\ncharacteristic Mn O vibrational frequencies, confirming the phase purity of\nmaterial. The electrochemical performance of beta MnO2 nanorods was evaluated\nusing cyclic voltammetry and galvanostatic charge and discharge measurements\nusing inhouse developed supercapacitor device assembly. We observed about 125 F\nper g specific capacitance for beta MnO2 nanorods electrode materials."
    },
    {
        "anchor": "Structural Contribution to the Ferroelectric Fatigue in Lead Zirconate\n  Titanate (PZT) Ceramics: Many ferroelectric devices are based on doped lead zirconate titanate (PZT)\nceramics with compositions near the morphotropic phase boundary (MPB), at which\nthe relevant material's properties approach their maximum. Based on a\nsynchrotron x-ray diffraction study of MPB PZT, bulk fatigue is unambiguously\nfound to arise from a less effective field induced tetragonal-to-monoclinic\ntransformation, at which the degradation of the polarization flipping is\ndetected by a less intense and more diffuse anomaly in the atomic displacement\nparameter of lead. The time dependence of the ferroelectric response on a\nstructural level down to 250 $\\mu$s confirms this interpretation in the time\nscale of the piezolectric strain response.",
        "positive": "Molecule-surface interaction from van der Waals-corrected semilocal\n  density functionals: the example of thiophene on transition-metal surfaces: Semi-local density functional approximations are widely used. None of them\ncan capture the long-range van der Waals (vdW) attraction between separated\nsubsystems, but they differ remarkably in the extent to which they capture\nintermediate-range vdW effects responsible for equilibrium bonds between\nneighboring small closed-shell subsystems. The local density approximation\n(LDA) often overestimates this effect, while the Perdew-Burke-Ernzerhof (PBE)\ngeneralized gradient approximation (GGA) underestimates it. The\nstrongly-constrained and appropriately normed (SCAN) meta-GGA often estimates\nit well. All of these semi-local functionals require an additive non-local\ncorrection such as the revised Vydrov-Van Voorhis 2010 (rVV10) to capture the\nlong-range part. This work reports adsorption energies and the corresponding\ngeometry of the aromatic thiophene (C$_4$H$_4$S) bound to transition metal\nsurfaces. The adsorption process requires a genuine interplay of covalent and\nweak binding and requires a simultaneously accurate description of surface and\nadsorption energies with the correct prediction of the adsorption site. All\nthese quantities must come from well balanced short and long-range correlation\neffects for a universally applicable method for weak interactions with chemical\naccuracy."
    },
    {
        "anchor": "Diffusive and Fluid-like Motion of Homochiral Domain Walls in Easy-Plane\n  Magnetic Strips: Propagation of easy-plane magnetic precession can enable more efficient spin\ntransport than conventional spin waves. Such easy-plane spin transport is\ntypically understood in terms of a hydrodynamic model, partially analogous to\nsuperfluids. Here, using micromagnetic simulations, we examine easy-plane spin\ntransport in magnetic strips as the motion of a train of domain walls rather\nthan as hydrodynamic flow. We observe that the motion transitions from\ndiffusive to fluid-like as the density of domain walls is increased. This\ntransition is most evident in notched nanostrips, where the the domain walls\nare pinned by the notch defect in the diffusive regime but propagate\nessentially unimpeded in the fluid-like regime. Our findings suggest that spin\ntransport via easy-plane precession, robust against defects, is achievable in\nstrips based on realistic metallic ferromagnets and hence amenable to practical\ndevice applications.",
        "positive": "Highly Accurate Local Pseudopotentials of Li, Na, and Mg for Orbital\n  Free Density Functional Theory: We present a method to make highly accurate pseudopotentials for use with\norbital-free density functional theory (OF-DFT) with given exchange-correlation\nand kinetic energy functionals, which avoids the compounding of errors of\nKohn-Sham DFT and OF-DFT. The pseudopotentials are fitted to reference\n(experimental or highly accurate quantum chemistry) values of interaction\nenergies, geometries, and mechanical properties, using a genetic algorithm.\nThis can enable routine large-scale ab initio simulations of many practically\nrelevant materials. Pseudopotentials for Li, Na, and Mg resulting in accurate\ngeometries and energies of different phases as well as of vacancy formation and\nbulk moduli are presented as examples."
    },
    {
        "anchor": "Giant Biquadratic Exchange in 2D Magnets and its Role in Stabilizing\n  Ferromagnetism of NiCl2 Monolayer: Two-dimensional (2D) van der Waals (vdW) magnets provide an ideal platform\nfor exploring, on the fundamental side, new microscopic mechanisms and for\ndeveloping, on the technological side, ultra-compact spintronic applications.\nSo far, bilinear spin Hamiltonians have been commonly adopted to investigate\nthe magnetic properties of 2D magnets, neglecting higher order magnetic\ninteractions. However, we here provide quantitative evidence of giant\nbiquadratic exchange interactions in monolayer NiX2 (X=Cl, Br and I), by\ncombining first-principles calculations and the newly developed machine\nlearning method for constructing Hamiltonian. Interestingly, we show that the\nferromagnetic ground state within NiCl2 single layers cannot be explained by\nmeans of bilinear Heisenberg Hamiltonian; rather, the nearest-neighbor\nbiquadratic interaction is found to be crucial. Furthermore, using a\nthree-orbitals Hubbard model, we propose that the giant biquadratic exchange\ninteraction originates from large hopping between unoccupied and occupied\norbitals on neighboring magnetic ions. On a general framework, our work\nsuggests biquadratic exchange interactions to be important in 2D magnets with\nedge-shared octahedra.",
        "positive": "Chemical Bonding of Transition-metal Co$_{13}$ Clusters with Graphene: We carried out density functional calculation to study Co$_{13}$ clusters on\ngraphene. We deposit several free isomers in different disposition respect to\nhexagonal lattice nodes, studying even the $hcp$ $2d$ isomer recently obtained\nas the most stable one. Surprisingly, Co$_{13}$ clusters bonded to graphene\nprefer $icosahedron-like$ structures where the low lying isomer is much\ndistorted, because it is linked with more bonds than in previous works. For any\nisomer the most stable position binds to graphene by the Co atoms that can lose\nelectrons. We find that the charge transfers between graphene and clusters are\nsmall enough to conclude that the Co-graphene binding is not ionic-like but\nchemical. Besides, the same order of stability among the different isomers on\ndoped graphene is well kept. These findings could also be of interest for\nmagnetic clusters on graphenic nanostructures such as ribbons and nanotubes."
    },
    {
        "anchor": "Coexistence of Logarithmic and SdH Quantum Oscillations in Ferromagnetic\n  Cr-doped Tellurium Single Crystals: We report the synthesis of transition-metal-doped ferromagnetic elemental\nsingle-crystal semiconductors with quantum oscillations using the physical\nvapor transport method. The 7.7 atom% Cr-doped Te crystals (Cr_Te) show\nferromagnetism, butterfly-like negative magnetoresistance in the low\ntemperature (< 3.8 K) and low field (< 0.15 T) region, and high Hall mobility,\ne.g., 1320 cm2 V-1 s-1 at 30 K and 350 cm2 V-1 s-1 at 300 K, implying that\nCr_Te crystals are ferromagnetic elemental semiconductors. When B // c // I,\nthe maximum negative MR is -27% at T = 20 K and B = 8 T. In the low temperature\nsemiconducting region, Cr_Te crystals show strong discrete scale invariance\ndominated logarithmic quantum oscillations when the direction of the magnetic\nfield B is parallel to the [100] crystallographic direction and show Landau\nquantization dominated Shubnikov-de Haas (SdH) oscillations for B // [210]\ndirection, which suggests the broken rotation symmetry of the Fermi pockets in\nthe Cr_Te crystals. The findings of coexistence of multiple quantum\noscillations and ferromagnetism in such an elemental quantum material may\ninspire more study of narrow bandgap semiconductors with ferromagnetism and\nquantum phenomena.",
        "positive": "ARPES and transport studies of the elemental topological insulator\n  $\u03b1$-Sn: Gray tin, also known as $\\alpha$-Sn, can be turned into a three-dimensional\ntopological insulator (3D-TI) by strain and finite size effects. Such room\ntemperature 3D-TI is peculiarly interesting for spintronics due to the\nspin-momentum locking along the Dirac cone (linear dispersion) of the surface\nstates. Angle resolved photoemission spectroscopy (ARPES) has been used to\ninvestigate the dispersion close to the Fermi level in thin (0\\,0\\,1)-oriented\nepitaxially strained films of $\\alpha$-Sn, for different film thicknesses as\nwell as for different capping layers (Al, AlO$_x$ and MgO). Indeed a proper\ncapping layer is necessary to be able to use $\\alpha$-Sn surface states for\nspintronics applications. In contrast with free surfaces or surfaces coated\nwith Ag, coating the $\\alpha$-Sn surface with Al or AlO$_x$ leads to a drop of\nthe Fermi level below the Dirac point, an important consequence for transport\nis the presence of bulk states at the Fermi level. $\\alpha$-Sn films coated by\nAlO$_x$ are studied by electrical magnetotransport: despite clear evidence of\nsurface states revealed by Shubnikov-de Haas oscillations, an important part of\nthe magneto-transport properties is governed by \"bulk\" electronic states\nattributed to the $\\Gamma 8$ band, as suggested by {\\it ab-initio}\ncalculations."
    },
    {
        "anchor": "On the ferromagnetic ground state of SmN: SmN is a ferromagnetic semiconductor with the unusual property of an\norbital-dominant magnetic moment that is largely cancelled by an antiparallel\nspin contribution, resulting in a near-zero net moment. However, there is a\nbasic gap in the understanding of the ferromagnetic ground state, with existing\ndensity functional theory calculations providing values of the $4f$ magnetic\nmoments at odds with experimental data. To clarify the situation, we employ an\neffective $4f$ Hamiltonian incorporating spin-orbit coupling, exchange, the\ncrystal field, and $J$-mixing to calculate the ground state $4f$ moments. Our\nresults are in excellent agreement with experimental data, revealing moderate\nquenching of both spin and orbital moments to magnitudes of $\\sim 2~\\mu_B$ in\nbulk SmN, enhanced to an average of $\\sim 3~\\mu_B$ in SmN layers within a\nSmN/GdN superlattice. These calculations provide insight into recent studies of\nSmN showing that it is an unconventional superconductor at low temperatures and\ndisplays twisted magnetization phases in magnetic heterostructures.",
        "positive": "Persistent photogenerated state attained by femtosecond laser\n  irradiation of thin $T_d$-MoTe$_2$: Laser excitation has emerged as a means to expose hidden states of matter and\npromote phase transitions on demand. Such laser induced transformations are\noften rendered possible owing to the delivery of spatially and/or temporally\nmanipulated light, carrying energy quanta well above the thermal background.\nHere, we report time-resolved broadband femtosecond (fs) transient absorption\nmeasurements on thin flakes of Weyl semimetal candidate $T_d$-MoTe$_2$\nsubjected to various levels and schemes of fs-photoexcitation. Our results\nreveal that impulsive fs-laser irradiation alters the interlayer behavior of\nthe low temperature $T_d$ phase as evidenced by the persistent disappearance of\nits characteristic coherent $^1$A$_1$ $=$ 13 cm$^{-1}$ shear phonon mode. We\nfound that this structural transformation withstands thermal annealing up to\n500 K, although it can be reverted to the 1$T$\\' phase by fs-laser treatment at\nroom temperature. Our work opens the door to reversible optical control of\ntopological properties."
    },
    {
        "anchor": "Scanning tunneling microscopy of Bi$_2$Te$_3$ films prepared by pulsed\n  laser deposition: from nanocrystalline structures to van der Waals epitaxy: Bi$_2$Te$_3$ is a material with high efficiency of thermoelectric energy\nconversion. Recently, it was also recognized as a topological insulator, and is\noften used as the basis for creation of other types of topological matter.\nPulsed laser deposition (PLD) is widely considered as a simple method for\ngrowing of multicomponent films, but not as a tool for van der Waals epitaxy.\nWe demonstrate here that the van der Waals epitaxy of Bi$_2$Te$_3$ is indeed\nimpossible in vacuum PLD, but is possible in the presence of a background gas,\nwhich is confirmed by the results of scanning tunneling microscopy and\nspectroscopy studies. Results of {\\it ab initio} calculations reproduce\ntunneling spectra of the first three terraces of epitaxial films of\nBi$_2$Te$_3$. In addition, an unusual hexagonal superstructure resembling a\ncharge-density wave is observed in overheated films.",
        "positive": "Coulomb interaction and charge neutrality: Pariser, Parr and Pople\n  Hamiltonian versus the Extended Hubbard Hamiltonian: The Extended Hubbard Hamiltonian used by the Condensed Matter community is\nnothing but a simplified version of the Pariser, Parr and Pople Hamiltonian,\nwell established in the Quantum Chemistry community as a powerful tool to\ndescribe the electronic structure of {\\pi}-conjugated planar Polycyclic\nAromatic Hydrocarbons (PAH). We show that whenever the interaction potential is\nnon-local, unphysical charge inhomogeneities may show up in finite systems,\nprovided that electrons are not neutralized by the ion charges. Increasing the\nsystem size does not solve the problem when the potential has an infinite\nrange, and for finite range potentials these charge inhomogeneities become\nslowly less important as the potential range decreases and/or the system size\nincreases. Dimensionality does also play a major role. Examples in\nbi-dimensional systems, such as planar PAH and graphene, are discussed to some\nextent."
    },
    {
        "anchor": "Sub-diffractional, volume-confined polaritons in a natural hyperbolic\n  material: hexagonal boron nitride: Strongly anisotropic media where the principal components of the dielectric\ntensor have opposite signs are called hyperbolic. Such materials length exhibit\nunique nanophotonic properties enabled by the highly directional propagation of\nslow-light modes localized at deeply sub-diffractional scales. While artificial\nhyperbolic metamaterials have been demonstrated, they suffer from high\nplasmonic losses and require complex nanofabrication, which in turn induces the\nsize-dependent limitations on optical confinement. The low-loss, mid-infrared,\nnatural hyperbolic material, hexagonal boron nitride is an attractive\nalternative. We observe four series of multiple (up to seven) 'hyperbolic\npolariton' modes in boron nitride nanocones in two spectral bands. The resonant\nmodes obey the predicted aspect ratio dependence and exhibit record-high\nquality factors (Q up to 283) in the strong confinement regime (lambda/86 in\nthe smallest structures). These observations assert hexagonal boron nitride as\na promising platform for studying novel regimes of light-matter interactions\nand nanophotonic device engineering.",
        "positive": "Thermoelectric Effects and Topological Insulators: The recent discovery of topological insulator (TI) offers new opportunities\nfor the development of thermoelectrics, because many TIs (like Bi$_2$Te$_3$)\nare excellent thermoelectric (TE) materials. In this review, we will first\ndescribe the general TE properties of TIs and show that the coexistence of the\nbulk and boundary states in TIs introduces unusual TE properties, including\nstrong size effects and anomalous Seebeck effect. Importantly, the TE figure of\nmerit $zT$ of TIs is no longer an intrinsic property, but depends strongly on\nthe geometric size. The geometric parameters of two-dimensional TIs can be\ntuned to enhance $zT$ to be significantly greater than 1. Then a few\nproof-of-principle experiments on three-dimensional TIs will be discussed,\nwhich observed unconventional TE phenomena that are closely related to the\ntopological nature of the materials. However, current experiments indicate that\nthe metallic surface states, if their advantage of high mobility is not fully\nutilized, would be detrimental to TE performance. Finally we provide an outlook\nfor future work on topological materials, which offers great possibilities to\ndiscover exotic TE effects and may lead to significant breakthroughs in\nimproving $zT$."
    },
    {
        "anchor": "Superionic diffusion through frustrated energy landscape: Solid-state materials with high ionic conduction are necessary to many\ntechnologies including all-solid-state Li-ion batteries. Understanding how\ncrystal structure dictates ionic diffusion is at the root of the development of\nfast ionic conductors. Here, we show that LiTi2(PS4)3 exhibits a Li-ion\ndiffusion coefficient about an order of magnitude higher than current\nstate-of-the-art lithium superionic conductors. We rationalize this observation\nby the unusual crystal structure of LiTi2(PS4)3 which offers no regular\ntetrahedral or octahedral sites for lithium to favorably occupy. This creates a\nsmooth, frustrated energy landscape resembling more the energy landscapes\npresent in liquids than in typical solids. This frustrated energy landscape\nleads to a high diffusion coefficient combining low activation energy with a\nhigh pre-factor.",
        "positive": "Temperature dependence of spin-transfer-induced switching of nanomagnets: We measure the temperature, magnetic-field, and current dependence for the\nswitching of nanomagnets by a spin-polarized current. Depending on current\nbias, switching can occur between either two static magnetic states or a static\nstate and a current-driven precessional mode. In both cases, the switching is\nthermally activated and governed by the sample temperature, not a higher\neffective magnetic temperature. The activation barriers for switching between\nstatic states depend linearly on current, with a weaker dependence for dynamic\nto static switching."
    },
    {
        "anchor": "Pore-geometry recognition: on the importance of quantifying similarity\n  in nanoporous materials: In most applications of nanoporous materials the pore structure is as\nimportant as the chemical composition as a determinant of performance. For\nexample, one can alter performance in applications like carbon capture or\nmethane storage by orders of magnitude by only modifying the pore structure\n(1,2). For these applications it is therefore important to identify the optimal\npore geometry and use this information to find similar materials. However, the\nmathematical language and tools to identify materials with similar pore\nstructures, but different composition, has been lacking. Here we develop a pore\nrecognition approach to quantify similarity of pore structures and classify\nthem using topological data analysis (3,4). Our approach allows us to identify\nmaterials with similar pore geometries, and to screen for materials that are\nsimilar to given top-performing structures. Using methane storage as a case\nstudy, we also show that materials can be divided into topologically distinct\nclasses -- and that each class requires different optimization strategies. In\nthis work we have focused on pore space, but our topological approach can be\ngeneralised to quantify similarity of any geometric object, which, given the\nmany different Materials Genomics initiatives (5,6), opens many interesting\navenues for big-data science.",
        "positive": "Measurement of Conduction and Valence Bands g-factors in a Transition\n  Metal Dichalcogenide Monolayer: The electron valley and spin degree of freedom in monolayer transition-metal\ndichalcogenides can be manipulated in optical and transport measurements\nperformed in magnetic fields. The key parameter for determining the Zeeman\nsplitting, namely the separate contribution of the electron and hole g-factor,\nis inaccessible in most measurements. Here we present an original method that\ngives access to the respective contribution of the conduction and valence band\nto the measured Zeeman splitting. It exploits the optical selection rules of\nexciton complexes, in particular the ones involving inter-valley phonons,\navoiding strong renormalization effects that compromise single particle\ng-factor determination in transport experiments. These studies yield a direct\ndetermination of single band g factors. We measure gc1= 0.86, gc2=3.84 for the\nbottom (top) conduction bands and gv=6.1 for the valence band of monolayer\nWSe2. These measurements are helpful for quantitative interpretation of optical\nand transport measurements performed in magnetic fields. In addition the\nmeasured g-factors are valuable input parameters for optimizing band structure\ncalculations of these 2D materials."
    },
    {
        "anchor": "Vapor deposition rate modifies anisotropic glassy structure of an\n  anthracene-based organic semiconductor: We control the anisotropic molecular packing of vapor-deposited glasses of\nABH113, a deuterated anthracene derivative with promise for future OLED\nmaterials, by changing the deposition rate and substrate temperature at which\nthey are prepared. We find that, at substrate temperatures from 0.65Tg to\n0.92Tg, deposition rate significantly modifies the orientational order in the\nvapor-deposited glasses as characterized by X-ray scattering and birefringence.\nBoth measures of anisotropic order can be described by a single deposition\nrate-substrate temperature superposition (RTS). This supports the applicability\nof the surface equilibration mechanism and generalizes the RTS principle from\nprevious model systems with liquid crystalline order to non-mesogenic organic\nsemiconductors. We find that vapor-deposited glasses of ABH113 have\nsignificantly enhanced density and thermal stability compared to their\ncounterparts prepared by liquid-cooling. For organic semiconductors, the\nresults of this study provide an efficient guide for using deposition rate to\nprepare stable glasses with controlled molecular packing.",
        "positive": "4He adsorbed inside (10,10) single walled carbon nanotubes: Diffusion Monte Carlo calculations on the adsorption of $^4$He in open-ended\nsingle walled (10,10) nanotubes are presented. We have found a first order\nphase transition separating a low density liquid phase in which all $^4$He\natoms are adsorbed close to the tube wall and a high density arrangement\ncharacterized by two helium concentric layers. The energy correction due to the\npresence of neighboring tubes in a bundle has also been calculated, finding it\nnegligible in the density range considered."
    },
    {
        "anchor": "Patterning and tuning of electrical and optical properties of graphene\n  by laser induced two-photon oxidation: Graphene, being an ultrathin, durable, flexible, transparent material with\nsuperior conductivity and unusual optical properties, promises many novel\napplications in electronics, photonics and optoelectronics. For applications in\nelectronics, patterning and modification of electrical properties is very\ndesirable since pristine graphene has no band gap. Here we demonstrate a simple\nall-optical patterning method for graphene, based on laser induced two-photon\noxidation. By tuning the intensity of irradiation and the number of pulses the\nlevel of oxidation can be controlled to high precision and, therefore, a band\ngap can be introduced and electrical and optical properties can be continuously\ntuned. Arbitrary complex patterning can be performed for air-suspended\nmonolayer graphene or for graphene on substrates. The method works at room\ntemperature in ambient air and no additional processing step is needed. The\npresented concept allows development of all-graphene electronic and\noptoelectronic devices and complex circuits with an all-optical method.",
        "positive": "High-throughput calculations of magnetic topological materials: The discoveries of intrinsically magnetic topological materials, including\nsemimetals with a large anomalous Hall effect and axion insulators, have\ndirected fundamental research in solid-state materials. Topological quantum\nchemistry has enabled the understanding of and the search for paramagnetic\ntopological materials. Using magnetic topological indices obtained from\nmagnetic topological quantum chemistry (MTQC), here we perform a\nhigh-throughput search for magnetic topological materials based on\nfirst-principles calculations. We use as our starting point the Magnetic\nMaterials Database on the Bilbao Crystallographic Server, which contains more\nthan 549 magnetic compounds with magnetic structures deduced from\nneutron-scattering experiments, and identify 130 enforced semimetals (for which\nthe band crossings are implied by symmetry eigenvalues), and topological\ninsulators. For each compound, we perform complete electronic structure\ncalculations, which include complete topological phase diagrams using different\nvalues of the Hubbard potential. Using a custom code to find the magnetic\nco-representations of all bands in all magnetic space groups, we generate data\nto be fed into the algorithm of MTQC to determine the topology of each magnetic\nmaterial. Several of these materials display previously unknown topological\nphases, including symmetry-indicated magnetic semimetals, three-dimensional\nanomalous Hall insulators and higher-order magnetic semimetals. We analyse\ntopological trends in the materials under varying interactions: 60 per cent of\nthe 130 topological materials have topologies sensitive to interactions, and\nthe others have stable topologies under varying interactions. We provide a\nmaterials database for future experimental studies and open-source code for\ndiagnosing topologies of magnetic materials."
    },
    {
        "anchor": "Negative Compressibility of Single Selenium Chain Confined in Zeolite\n  Pore: Pressure induced structural and electronic transitions of Se helical chains\nconfined inside nano-channels are studied. Raman scattering and optical\nabsorption experiments show strong evidence of band gap reduction under high\npressure. Ab initio calculations reveal that under hydrostatic compression, the\nSe chains should elongate and the change in morphology leads to a softening of\nphonons and narrowing of band gaps, and these signatures are observed in\nexperiments. Our investigation demonstrates a negative compressibility in one\ndimension.",
        "positive": "Structural, Magnetic and Electron Transport Properties of\n  Ordered-Disordered Perovskite Cobaltites: Rare earth perovskite cobaltites are increasingly recognized as materials of\nimportance due to rich physics and chemistry in their ordered-disordered\nstructure for the same composition. Apart from colossal magnetoresistance\neffect, like manganites, the different forms of cobaltites exhibit interesting\nphenomena including spin, charge and orbital ordering, electronic phase\nseparation, insulator-metal transition, large thermoelectric power at low\ntemperature. Moreover, the cobaltites which display colossal magnetoresistance\neffect could be used as read heads in magnetic data storage and also in other\napplications depending upon their particular properties. The A-site\nordereddisordered cobaltites exhibit ferromagnetism and metal-insulator\ntransitions as well as other properties depending on the composition, size of\nA-site cations and various external factors such as pressure, temperature,\nmagnetic field etc. Ordered cobaltites, having a 112-type layered structure,\nare also reported to have an effectively stronger electron coupling due to\nlayered A-site cationic ordering. Most importantly for the present article we\nfocus on La-Ba-Co-O based ordered-disordered perovskite phases, which exhibit\ninteresting magnetic and electron transport properties with ferromagnetic\ntransition, TC ~ 177K, and it being the first member of lanthanide series.\nZener double exchange mechanism considered to be crucial for understanding\nbasic physics of the ferromagneticmetallic phase, yet does not explain clearly\nthe insulating-type phase. In terms of electron transport the\nferromagnetic-metallic or insulating/semiconducting states have been discussed\nin the present article with different types of hopping model."
    },
    {
        "anchor": "GTPack: A Mathematica group theory package for application in\n  solid-state physics and photonics: We present the Mathematica group theory package GTPack providing about 200\nadditional modules to the standard Mathematica language. The content ranges\nfrom basic group theory and representation theory to more applied methods like\ncrystal field theory, tight-binding and plane-wave approaches capable for\nsymmetry based studies in the fields of solid-state physics and photonics.\nGTPack is freely available via http://GTPack.org. The package is designed to be\neasily accessible by providing a complete Mathematica-style documentation, an\noptional input validation and an error strategy. We illustrate the basic\nframework of the package and show basic examples to present the functionality.\nFurthermore, we give a complete list of the implemented commands including\nreferences for algorithms within the supplementary material.",
        "positive": "Diffraction of slow neutrons by holographic SiO_2 nanoparticle-polymer\n  composite gratings: Diffraction experiments with holographic gratings recorded in SiO$_2$\nnanoparticle-polymer composites have been carried out with slow neutrons. The\ninfluence of parameters such as nanoparticle concentration, grating thickness\nand grating spacing on the neutron-optical properties of such materials has\nbeen tested. Decay of the grating structure along the sample depth due to\ndisturbance of the recording process becomes an issue at grating thicknesses of\nabout 100 microns and larger. This limits the achievable diffraction efficiency\nfor neutrons. As a solution to this problem, the Pendell\\\"{o}sung interference\neffect in holographic gratings has been exploited to reach a diffraction\nefficiency of 83% for very cold neutrons."
    },
    {
        "anchor": "Spin-spin interactions in solids from mixed all-electron and\n  pseudopotential calculations $-$ a path to screening materials for spin\n  qubits: Understanding the quantum dynamics of spin defects and their coherence\nproperties requires accurate modeling of spin-spin interaction in solids and\nmolecules, for example by using spin Hamiltonians with parameters obtained from\nfirst-principles calculations. We present a real-space approach based on\ndensity functional theory for the calculation of spin-Hamiltonian parameters,\nwhere only selected atoms are treated at the all-electron level, while the rest\nof the system is described with the pseudopotential approximation. Our approach\npermits calculations for systems containing more than 1000 atoms, as\ndemonstrated for defects in diamond and silicon carbide. We show that only a\nsmall number of atoms surrounding the defect needs to be treated at the\nall-electron level, in order to obtain an overall all-electron accuracy for\nhyperfine and zero-field splitting tensors. We also present results for\ncoherence times, computed with the cluster correlation expansion method,\nhighlighting the importance of accurate spin-Hamiltonian parameters for\nquantitative predictions of spin dynamics.",
        "positive": "Room temperature dynamic correlation between methylammonium molecules in\n  lead-iodine based perovskites: An ab-initio molecular dynamics perspective: The high efficiency of lead organo-metal-halide perovskite solar cells has\nraised many questions about the role of the methylammonium (MA) molecules in\nthe Pb-I framework. Experiments indicate that the MA molecules are able to\n'freely' spin around at room temperature even though they carry an intrinsic\ndipole moment. We have performed large supercell (2592 atoms) finite\ntemperature ab-initio molecular dynamics calculations to study the correlation\nbetween the molecules in the framework. An underlying long range\nanti-ferroelectric ordering of the molecular dipoles is observed. The dynamical\ncorrelation between neighboring molecules shows a maximum around room\ntemperature in the mid-temperature phase. In this phase, the rotations are slow\nenough to (partially) couple to neighbors via the Pb-I cage. This results in a\ncollective motion of neighboring molecules in which the cage acts as the\nmediator. At lower and higher temperatures the motions are less correlated."
    },
    {
        "anchor": "Role of Dimensionality and Size in Controlloing the Drag Seebeck\n  Coefficient of Doped Silicon Nanostructures: A Fundamental Understanding: In this theoretical study, we examine the influence of dimensionality, size\nreduction, and heat-transport direction on the phonon-drag contribution to the\nSeebeck coefficient of silicon nanostructures. Phonon-drag contribution, which\narises from the momentum transfer between out-of-equilibrium phonon populations\nand charge carriers, significantly enhances the thermoelectric coefficient. Our\nimplementation of the phonon drag term accounts for the anisotropy of\nnanostructures, such as thin films and nanowires, through the boundary- and\nmomentum-resolved phonon lifetime. Our approach also takes into account the\nspin-orbit coupling which turns out to be crucial for hole transport. We\nreliably quantify the phonon drag contribution at various doping levels,\ntemperatures, and nanostructure geometries for both electrons and holes in\nsilicon nanostructures. Our results support the recent experimental findings,\nshowing that a part of phonon drag contribution survives in 100 nm silicon\nnanostructures.",
        "positive": "The growth of bismuth on Bi$_2$Se$_3$ and the stability of the first\n  bilayer: Bi(0001) films with thicknesses up to several bilayers (BLs) are grown on\nSe-terminated Bi$_2$Se$_3$(0001) surfaces, and low energy electron diffraction\n(LEED), low energy ion scattering (LEIS) and atomic force microscopy (AFM) are\nused to investigate the surface composition, topography and atomic structure.\nFor a single deposited Bi BL, the lattice constant matches that of the\nsubstrate and the Bi atoms adjacent to the uppermost Se atoms are located at\nfcc-like sites. When a 2nd Bi bilayer is deposited, it is incommensurate with\nthe substrate. As the thickness of the deposited Bi film increases further, the\nlattice parameter evolves to that of bulk Bi(0001). After annealing a multiple\nBL film at 120{\\deg}C, the first commensurate Bi BL remains intact, but the\nadditional BLs aggregate to form thicker islands of Bi. These results show that\na single Bi BL on Bi$_2$Se$_3$ is a particularly stable structure. After\nannealing to 490{\\deg}C, all of the excess Bi desorbs and the Se-terminated\nBi$_2$Se$_3$ surface is restored."
    },
    {
        "anchor": "Anharmonic Host Lattice Dynamics Enable Fast Ion Conduction in\n  Superionic AgI: Basic understanding of the driving forces of ion conduction in solids is\ncritical to the development of new solid-state ion conductors. Physical\nunderstanding of ion conduction is limited due to strong deviations from\nharmonic vibrational dynamics in these systems that are difficult to\ncharacterize experimentally and theoretically. We overcome this challenge in\nsuperionic AgI by combining THz-frequency Raman polarization-orientation\nmeasurements and ab-initio molecular dynamics computations. Our findings\ndemonstrate clear signatures of strong coupling between the mobile ions and\nhost lattice that are of importance to the diffusion process. We first derive a\ndynamic structural model from the Raman measurements that captures the\nsimultaneous crystal-like and fluid-like properties of this fast-ion conductor.\nThen we show and discuss the importance of anharmonic relaxational motion that\narises from the iodine host lattice by demonstrating its strong impact on ion\nconduction in superionic AgI.",
        "positive": "Excitons in \\ce{Mg(OH)2} and \\ce{Ca(OH)2} from \\textit{ab initio}\n  calculations: By using \\textit{ab initio} calculations with the HSE06 hybrid functional and\nGW approximation combined with numerical solution of the Bethe Salpeter\nequation (GW-BSE) we predict the existence of diverse number of excitonic\nstates in multifunctional hydroxides \\ce{\\textit{X}(OH)2} (\\textit{X}= Mg and\nCa) that were not previously reported experimentally or theoretically.\nImaginary part of the dielectric function and reflectivity spectra show very\nstrong peaks corresponding to the electron-hole pair states of large binding\nenergy. The origin of the excitons is attributed to strong localization of the\nhole and electron associated to oxygen $2p_x, 2p_y$ occupied states as well as\nto oxygen and earth metal $s$ empty states, respectively. The results have\nimportant implications for different applications of the materials in\noptoelectronic devices."
    },
    {
        "anchor": "Flat-band and multi-dimensional fermions in Pb10(PO4)6O4: Employing a combination of first-principles calculations and low-energy\neffective models, we present a comprehensive investigation on the electronic\nstructure of Pb$_{10}$(PO$_{4}$)$_{6}$O$_{4}$, which exhibits remarkable\nquasi-one-dimensional flat-band around the Fermi level that contains novel\nmulti-dimensional fermions. These flat bands predominantly originate from\n$p_x/p_y$ orbital of the oxygen molecules chain at $4e$ Wyckoff positions, and\nthus can be well-captured by a four-band tight-binding model. Furthermore, the\nabundant crystal symmetry inherent to Pb$_{10}$(PO$_{4}$)$_{6}$O$_{4}$ provides\nan ideal platform for the emergence of various multi-dimensional fermions,\nincluding a 0D four-fold degenerated Dirac fermion with quadratic dispersion, a\n1D quadratic/linear nodal-line (QNL/LNL) fermion along symmetric $k$-paths, 1D\nhourglass nodal-line (HNL) fermion linked to the Dirac fermion, and a 2D\nsymmetry-enforced nodal surface (NS) found on the $k_z$=$\\pi$ plane. Moreover,\nwhen considering the weak ferromagnetic order, Pb$_{10}$(PO$_{4}$)$_{6}$O$_{4}$\ntransforms into a rare semi-half-metal, which is characterized by the presence\nof Dirac fermion and HNL fermion at the Fermi level for a single spin channel\nexhibiting 100$\\%$ spin polarization. Our findings reveal the coexistence of\nflat bands, diverse topological semimetal states and ferromagnetism within in\nPb$_{10}$(PO$_{4}$)$_{6}$O$_{4}$, which may provide valuable insights for\nfurther exploring intriguing interplay between superconductivity and exotic\nelectronic states.",
        "positive": "Light-matter interaction of single semiconducting AlGaN nanowire and\n  noble metal Au nanoparticle in the sub-diffraction limit: The near field scanning optical microscopy (NSOM) is not only a tool for\nimaging of sub-diffraction limited objects but also a prominent characteristic\ntool for understanding the intrinsic properties of the nanostructures. In order\nto understand the light-matter interactions in the near field regime using NSOM\ntechnique with an excitation of 532 nm (2.33 eV), we selected an isolated\nsingle semiconducting AlGaN nanowire (NW) of diameter ~120 nm grown via vapor\nliquid solid (VLS) mechanism along with metallic Au nanoparticle (NP) catalyst.\nThe role of electronic transitions from different native defect related energy\nstates of AlGaN are discussed in understanding the NSOM images for the\nsemiconducting NW. The effect of strong surface plasmon resonance absorption of\nexcitation laser in the NSOM images for Au NP, involved in the VLS growth\nmechanism of NWs, is also observed. Keywo"
    },
    {
        "anchor": "Topological semimetals protected by off-centered symmetries in\n  nonsymmorphic crystals: Topological semimetals have energy bands near the Fermi energy sticking\ntogether at isolated points/lines/planes in the momentum space, which are often\naccompanied by stable surface states and intriguing bulk topological responses.\nAlthough it has been known that certain crystalline symmetries play an\nimportant role in protecting band degeneracy, a general recipe for stabilizing\nthe degeneracy, especially in the presence of spin-orbit coupling, is still\nlacking. Here we show that a class of novel topological semimetals with\npoint/line nodes can emerge in the presence of an off-centered rotation/mirror\nsymmetry whose symmetry line/plane is displaced from the center of other\nsymmorphic symmetries in nonsymmorphic crystals. Due to the partial translation\nperpendicular to the rotation axis/mirror plane, an off-centered\nrotation/mirror symmetry always forces two energy bands to stick together and\nform a doublet pair in the relevant invariant line/plane in momentum space.\nSuch a doublet pair provides a basic building block for emerging topological\nsemimetals with point/line nodes in systems with strong spin-orbit coupling.",
        "positive": "Optical Manipulation of Magnetic Vortex Visualized in situ by 4D\n  Electron Microscopy: Understanding the fundamental dynamics of topological vortex and antivortex\nnaturally formed in micro/nanoscale ferromagnetic building blocks under\nexternal perturbations is crucial to magnetic vortex based information\nprocessing and spintronic devices. All previous studies have focused on\nmagnetic vortex-core switching via external magnetic fields, spin-polarized\ncurrents, or spin waves, which have largely prohibited the investigation of\nnovel spin configurations that could emerge from the ground states in\nferromagnetic disks and their underlying dynamics. Here, we report in situ\nvisualization of femtosecond laser quenching induced magnetic vortex change in\nvarious symmetric ferromagnetic Permalloy disks by Lorentz phase imaging using\n4D electron microscopy. Besides the switching of magnetic vortex chirality and\npolarity, we observed with distinct occurrence frequencies a plenitude of\ncomplex magnetic structures that have never been observed by magnetic field or\ncurrent assisted switching. These complex magnetic structures consist of a\nnumber of newly created topological magnetic defects (vortex and antivortex)\nstrictly conserving the topological winding number, demonstrating the direct\nimpact of topological invariant on the magnetization dynamics in ferromagnetic\ndisks. Their spin configurations show mirror or rotation symmetry due to the\ngeometrical confinement of the disks. Combined micromagnetic simulations with\nthe experimental observations reveal the underlying magnetization dynamics and\nformation mechanism of the optical quenching induced complex magnetic\nstructures. Their distinct occurrence rates are pertinent to their\nformation-growth energetics and pinning effects at the disk edge. Based on\nthese findings, we propose a paradigm of optical-quenching-assisted fast\nswitching of vortex cores for the control of magnetic vortex based information\nrecording and spintronic devices."
    },
    {
        "anchor": "Lattice dynamics of coesite: The lattice dynamics of coesite has been studied by a combination of diffuse\nx-ray scattering, inelastic x-ray scattering and an ab initio lattice dynamics\ncalculation. The combined technique gives access to the full lattice dynamics\nin harmonic description and thus eventually provides detailed information on\nthe elastic properties, the stability and metastability of crystalline systems.\nThe experimentally validated calculation was used for the investigation of\neigenvectors, mode character and their influence on the density of vibrational\nstates. High symmetry sections of the reciprocal space distribution of diffuse\nscattering and inelastic x-ray scattering spectra as well as the density of\nvibrational states and the dispersion relation are reported and compared to the\ncalculation. A critical point at the zone boundary is found to contribute\nstrongly to the main peak of the low energy part in the density of vibrational\nstates. Comparison with the most abundant SiO2 polymorph - alpha-quartz -\nreveals similarities and distinct differences in the low-energy vibrational\nproperties.",
        "positive": "First-principles predictions of out-of-plane group IV and V dimers as\n  high-symmetry high-spin defects in hexagonal boron nitride: Hexagonal boron nitride (h-BN) has been recently found to host a variety of\nquantum point defects, which are promising candidates as single-photon sources\nfor solid-state quantum nanophotonics applications. Most recently, optically\naddressable spin qubits in h-BN have been the focus of intensive research due\nto their unique potential in quantum computing, communication, and sensing.\nHowever, the number of high-symmetry high-spin defects that are desirable for\ndeveloping spin qubits in h-BN is highly limited. Here, we combine density\nfunctional theory (DFT) and quantum embedding theories to show that\nout-of-plane XY dimer defects (X, Y = C, N, P, Si) form a new class of stable\nC3v spin-triplet defects in h-BN. We find that the dimer defects have a robust\n3A2 ground state and 3E excited state, both of which are isolated from the h-BN\nbulk states. We show that 1E and 1A shelving states exist and they are\npositioned between the 3E and 3A2 states for all the dimer defects considered\nin this study. To support future experimental identification of the XY dimer\ndefects, we provide an extensive characterization of the defects in terms of\ntheir spin and optical properties. We predict that the zero-phonon line of the\nspin-triplet XY defects lies in the visible range (800 nm - 500 nm). We compute\nthe zero-field splitting of the dimers to range from 1.79 GHz (SiP) to 29.5 GHz\n(CN). Our results broaden the scope of high-spin defect candidates that would\nbe useful for the development of spin-based solid-state quantum technologies in\ntwo-dimensional hexagonal boron nitride."
    },
    {
        "anchor": "High Pressure Structural Stability of Multiferroic Hexagonal REMnO3: Structural changes in REMnO3 (RE= Y, Ho, Lu) under high pressure were\nexamined by synchrotron x-ray diffraction methods at room temperature.\nCompression occurs more readily in the ab plane than along the c-axis. Under\nhydrostatic pressure (~11 GPa), the atoms hold their approximate ambient\nfractional positions in the unit cell and the spontaneous polarization shows no\nsignificant change. With increased pressure, a pressure-induced hexagonal to\northorhombic phase transition was observed starting at ~ 22GPa for Lu(Y)MnO3. A\nsmall volume fraction of Lu(Y)MnO3 is converted to the orthorhombic phase when\nthe pressure is increased to 35 GPa and the orthorhombic phase is maintained on\npressure release. High pressure IR absorption spectroscopy and Mn K-edge near\nedge x-ray absorption spectroscopy confirm that the hexagonal P63cm structure\nis stable below ~20 GPa and the environment around Mn ion is not changed.\nShifts in the unoccupied p-band density of states with pressure are observed in\nthe Mn K-Edge spectra. A schematic pressure-temperature phase diagram is given\nfor the small ion REMnO3 system.",
        "positive": "Bulk-to-surface misorientation and the spin texture of topological\n  insulators: Weak topological insulators possess a symmetry related set of Dirac-Weyl\ncones in the surface Brillouin zone, implying misorientation between the\nprinciple axis of the low energy manifold of the bulk and the surface normal.\nWe show that this feature of weak topological insulators comes with a hidden\nrichness of surface spin textures, and that by misorientation a helical texture\ncan become an unusual hyperbolic spin texture. We illustrate this effect by\ncomparison of the $M$-point and $\\Gamma$-point Dirac-Weyl cones on the (111)\nsurface of the crystalline topological insulator SnTe."
    },
    {
        "anchor": "Bipolar polaron pair recombination in P3HT/PCBM solar cells: The unique properties of organic semiconductors make them versatile base\nmaterials for many applications ranging from light emitting diodes to\ntransistors. The low spin-orbit coupling typical for carbon-based materials and\nthe resulting long spin lifetimes give rise to a large influence of the\nelectron spin on charge transport which can be exploited in spintronic devices\nor to improve solar cell efficiencies. Magnetic resonance techniques are\nparticularly helpful to elucidate the microscopic structure of paramagnetic\nstates in semiconductors as well as the transport processes they are involved\nin. However, in organic devices the nature of the dominant spin-dependent\nprocesses is still subject to considerable debate. Using multi-frequency pulsed\nelectrically detected magnetic resonance (pEDMR), we show that the\nspin-dependent response of P3HT/PCBM solar cells at low temperatures is\ngoverned by bipolar polaron pair recombination involving the positive and\nnegative polarons in P3HT and PCBM, respectively, thus excluding a unipolar\nbipolaron formation as the main contribution to the spin-dependent charge\ntransfer in this temperature regime. Moreover the polaron-polaron coupling\nstrength and the recombination times of polaron pairs with parallel and\nantiparallel spins are determined. Our results demonstrate that the pEDMR pulse\nsequences recently developed for inorganic semiconductor devices can very\nsuccessfully be transferred to the study of spin and charge transport in\norganic semiconductors, in particular when the different polarons can be\ndistinguished spectrally.",
        "positive": "Lattice vibrations in the harmonic approximation: We present some theoretical results on the lattice vibrations that are\nnecessary for a concise derivation of the Debye-Waller factor in the harmonic\napproximation. First we obtain an expression for displacement of an atom in a\ncrystal lattice from its equilibrium position. Then we show that an atomic\ndisplacement has the Gaussian distribution. Finally, we obtain the\ncomputational formula for the Debye-Waller factor in the Debye model."
    },
    {
        "anchor": "All-electron quantum Monte Carlo calculations for the noble gas atoms He\n  to Xe: We report all-electron variational and diffusion quantum Monte Carlo (VMC and\nDMC) calculations for the noble gas atoms He, Ne, Ar, Kr, and Xe. The\ncalculations were performed using Slater-Jastrow wave functions with\nHartree-Fock single-particle orbitals. The quality of both the optimized\nJastrow factors and the nodal surfaces of the wave functions declines with\nincreasing atomic number Z, but the DMC calculations are tractable and well\nbehaved in all cases. We discuss the scaling of the computational cost of DMC\ncalculations with Z.",
        "positive": "Tuning the electronic and optical properties of hg-C$_3$N$_4$, quantum\n  dots with edge-functionalization: A computational perspective: In this work, we have systematically investigated the structural, electronic,\nvibrational and optical properties of the edge-functionalized hg-C3N4 quantum\ndots with the aim of exploring their possible applications in solar cells and\nother optoelectronic devices such as light-emitting diodes. The functional\ngroups considered in this work are methyl (-CH$_3$), fluorine (-F), and\noxygenated groups such as aldehyde (-CHO), carboxyl (-COOH), ketone\n(-COCH$_3$), and hydroxyl (-OH) groups. The edge-functionalization resulted in\nsignificant tuning of the electronic, vibrational, and optical properties.\nThus, their structural fingerprints are present in both their vibrational and\noptical properties, thereby allowing their detection both in the Raman as well\nas optical spectroscopies. It is observed that edge functionalization broadens\nthe energy range of optical absorption, leading to coverage of most of the\nultraviolet and visible regions. This implies that the edge-functionalization\nof hg-C$_3$N$_4$ quantum dots can be used in a variety of optoelectronic\ndevices such as solar cells and light emitting diodes."
    },
    {
        "anchor": "Deconvolving Instrumental and Intrinsic Broadening in Excited State\n  X-ray Spectroscopies: Intrinsic and experimental mechanisms frequently lead to broadening of\nspectral features in excited-state spectroscopies. For example, intrinsic\nbroadening occurs in x-ray absorption spectroscopy (XAS) measurements of heavy\nelements where the core-hole lifetime is very short. On the other hand,\nnonresonant x-ray Raman scattering (XRS) and other energy loss measurements are\nmore limited by instrumental resolution. Here, we demonstrate that the\nRichardson-Lucy (RL) iterative algorithm provides a robust method for\ndeconvolving instrumental and intrinsic resolutions from typical XAS and XRS\ndata. For the K-edge XAS of Ag, we find nearly complete removal of ~9.3 eV FWHM\nbroadening from the combined effects of the short core-hole lifetime and\ninstrumental resolution. We are also able to remove nearly all instrumental\nbroadening in an XRS measurement of diamond, with the resulting improved\nspectrum comparing favorably with prior soft x-ray XAS measurements. We present\na practical methodology for implementing the RL algorithm to these problems,\nemphasizing the importance of testing for stability of the deconvolution\nprocess against noise amplification, perturbations in the initial spectra, and\nuncertainties in the core-hole lifetime.",
        "positive": "Establishing phase diagram for the band engineering in p-type PbTe/SnTe\n  from elementary electronic structure understanding: Band engineering is an important mechanism to increase the thermopower of\nthermoelectric materials by reconstructing the band structure near Fermi level.\nPbTe and SnTe are the most representative systems in which band engineering\nwere achieved by various dopants. Starting with the elementary understanding of\nthe band structures, we established the phase diagram for the band engineering\nin p-type PbTe/SnTe by constructing an s-p bonding model. We show that the\neffects of band tuning are mainly determined by an inherent parameter of doping\nelement: the s orbital energy level. With the phase diagram, all the related\nexperimental observations can be consistently explained, moreover, undiscovered\neffective dopants become foreseeable. Our study discovers an applicable\ncriteria to pick up proper dopants from the periodic table directly, and the\nanalytical method can be adopted to more thermoelectric materials."
    },
    {
        "anchor": "Electron spectrum of epitaxial graphene monolayers: Epitaxial graphene on SiC possesses, quite remarkably, an electron spectrum\nsimilar to that of freestanding samples. Yet, the coupling to the substrate,\nalbeit small, affects the quasiparticle properties. Combining \\emph{ab initio}\ncalculations with symmetry analysis, we derive a modified Dirac-Weyl\nHamiltonian for graphene epilayers. While for the epilayer on the C-face the\nDirac cone remains almost intact, for epilayers on the Si-face the band\nsplitting is about 30\\,meV. At certain energies, the Dirac bands are\nsignificantly distorted by the resonant interaction with interface states,\nwhich should lead to mobility suppression, especially on the Si-face.",
        "positive": "Strong impact of grain boundaries on the thermoelectric properties of\n  non-equilibrium synthesized p-type Ce1.05Fe4Sb12.04 filled skutterudites with\n  nanostructure: p-type Ce1.05Fe4Sb12.04 filled skutterudites with much improved\nthermoelectric properties have been synthesized by rapidly converting nearly\namorphous ribbons into crystalline pellets under pressure. It is found that\nthis process greatly suppresses grain growth and second phase\nformation/segregation, and hence results in the samples consisting of\nnano-sized grains with strongly-coupled grain boundaries, as observed by\ntransmission electron microscopy. The room temperature carrier mobility in\nthese samples is significantly higher (nearly double) than those in the samples\nof the same starting composition made by the conventional solid-state reaction.\nNanostructure reduces the lattice thermal conductivity, while cleaner grain\nboundaries permit higher electron conduction."
    },
    {
        "anchor": "Spinodal decomposition of an ABv model alloy: Patterns at unstable\n  surfaces: We develop mean-field kinetic equations for a lattice gas model of a binary\nalloy with vacancies (ABv model) in which diffusion takes place by a vacancy\nmechanism. These equations are applied to the study of phase separation of\nfinite portions of an unstable mixture immersed in a stable vapor. Due to a\nlarger mobility of surface atoms, the most unstable modes of spinodal\ndecomposition are localized at the vapor-mixture interface. Simulations show\ncheckerboard-like structures at the surface or surface-directed spinodal waves.\nWe determine the growth rates of bulk and surface modes by a linear stability\nanalysis and deduce the relation between the parameters of the model and the\nstructure and length scale of the surface patterns. The thickness of the\nsurface patterns is related to the concentration fluctuations in the initial\nstate.",
        "positive": "Cobaltocene Encapsulation Into Single-walled Carbon Nanotubes: A\n  Molecular Dynamics Investigation: Recently (PRL 96, 106804 (2006)) it was suggested that cobaltocene(CC)\nmolecules encapsulated into (7,7) carbon nanotubes (CNT@(7,7)) could be the\nbasis for new spintronic devices. We show here based on impact molecular\ndynamics and DFT calculations that when dynamical aspects are explicitly\nconsidered the CC encapsulation into CNT@(7,7) does not occur, it is prevented\nby a dynamic barrier mainly due to van der Waals interactions. Our results show\nthat CNT@(13,0) having enough axial space for encapsulation but no enough one\nto allow freely rotation of the cobaltocene molecule would be a feasible\ncandidate to such application."
    },
    {
        "anchor": "Applications of DFT+DMFT in Materials Science: First principles methods can provide insight into materials that is otherwise\nimpossible to acquire. Density Functional Theory (DFT) has been the first\nprinciples method of choice for numerous applications, but it falls short of\npredicting the properties of correlated materials. First principles Density\nFunctional Theory + Dynamical Mean Field Theory (DFT+DMFT) is a powerful tool\nthat can address these shortcomings of DFT when applied to correlated metals.\nIn this brief review, which is aimed at non-experts, we review the basics and\nsome applications of DFT+DMFT.",
        "positive": "A mechanism-based multi-trap phase field model for hydrogen assisted\n  fracture: We present a new mechanistic, phase field-based formulation for predicting\nhydrogen embrittlement. The multi-physics model developed incorporates, for the\nfirst time, a Taylor-based dislocation model to resolve the mechanics of crack\ntip deformation. This enables capturing the role of dislocation hardening\nmechanisms in elevating the tensile stress, hydrogen concentration and\ndislocation trap density within tens of microns ahead of the crack tip. The\nconstitutive strain gradient plasticity model employed is coupled to a phase\nfield formulation, to simulate the fracture process, and to a multi-trap\nhydrogen transport model. The analysis of stationary and propagating cracks\nreveals that the modelling framework presented is capable of adequately\ncapturing the sensitivity to the hydrogen concentration, the loading rate, the\nmaterial strength and the plastic length scale. In addition, model predictions\nare compared to experimental data of notch tensile strength versus hydrogen\ncontent on a high-strength steel; a very good agreement is attained. We define\nand implement both atomistic-based and phenomenological hydrogen degradation\nlaws and discuss similarities, differences and implications for the development\nof parameter-free hydrogen embrittlement models."
    },
    {
        "anchor": "Interplay of lattice distortion and bands near the Fermi level in\n  $A$TiO$_3$ ($A$=Ca, Sr, Ba): The structural and electronic properties of $A$TiO$_3$ ($A$=Ca, Sr, Ba) have\nbeen investigated under strain-free situation and with realistic constraints\nusing first-principles calculations. We endeavored to find out the interplay\nbetween mild lattice distortions and bandgap in three $A$TiO$_3$ family members\nthat has remained skeptical to date. We found out that the electronic structure\nwas particularly sensitive to strains (compressive or tensile) as expected in\nmost materials science studies. Our results indicate that under mild strains;\nthe bandgap ($E_{gap}$), increased under compression and decreased under\ntension. In all the three materials, the bandgap and the lattice parameter\n($a$) were found to relate as $E_{gap}\\propto \\frac{1}{a^x}$ for mild\ndistortions with $2.19<x<3.1$. All these changes are attributed to the\ninterplay of electrostatics and covalency in these crystals. This work acts as\na yardstick on bandgap engineering to achieve desired properties in these\ntitanates for feasible future applications.",
        "positive": "Modeling functional piezoelectricity in perovskite superlattices with\n  competing instabilities: Based on the locality principle of insulating superlattices, we apply the\nmethod of Wu {\\it et al} [Phys. Rev. Letter {\\bf 101}, 087610 (2008)] to the\npiezoelectric strains of individual layers under fixed displacement field. For\na superlattice of arbitrary stacking sequence an accurate model is acquired for\npredicting piezoelectricity. By applying the model in the superlattices where\nferroelectric and antiferrodistortive modes are in competition, functional\npiezoelectricity can be achieved. A strong nonlinear effect is observed and can\nbe further engineered in the PbTiO$_3$/SrTiO$_3$ superlattice and an interface\nenhancement of piezoelectricity is found in the BaTiO$_3$/CaTiO$_3$\nsuperlattice."
    },
    {
        "anchor": "Effect of transition layers on the electromagnetic properties of\n  composites containing conducting fibres: The approach to calculating the effective dielectric and magnetic response in\nbounded composite materials is developed. The method is essentially based on\nthe renormalisation of the dielectric matrix parameters to account for the\nsurface polarisation and the displacement currents at the interfaces. This\nmakes it possible the use of the effective medium theory developed for\nunbounded materials, where the spatially-dependent local dielectric constant\nand magnetic permeability are introduced. A detailed mathematical analysis is\ngiven for a dielectric layer having conducting fibres with in-plane positions.\nThe surface effects are most essential at microwave frequencies in\ncorrespondence to the resonance excitation of fibres. In thin layers (having a\nthickness of the transition layer), the effective dielectric constant has a\ndispersion region at much higher frequencies compared to those for unbounded\nmaterials, exhibiting a strong dependence on the layer thickness. For the\ngeometry considered, the effective magnetic permeability differs slightly from\nunity and corresponds to the renormalised matrix parameter. The magnetic effect\nis due entirely to the existence of the surface displacement currents.",
        "positive": "Effect of the Bloch-Siegert Shift on the Frequency Responses of Rabi\n  Oscillations in the Case of Nutation Resonance: The dynamics of a two-level spin system dressed by bichromatic radiation is\nstudied under the conditions of double resonance when the frequency of one\n(microwave) field is equal to the Larmor frequency of the spin system and the\nfrequency of the other (radio-frequency) field \\omega_{rf} is close to the Rabi\nfrequency \\omega_{1} in a micro-wave field. It is shown theoretically that Rabi\noscillations between dressed-spin states with the frequency \\epsilon are\naccompanied by higher-frequency oscillations at frequencies n\\omega_{rf} and\nn\\omega_{rf}\\pm \\epsilon, where n = 1, 2, .... The most intense among these are\nthe signals corresponding to n = 1. The counter-rotating (antiresonance)\ncomponents of the RF field give rise to a shift of the dressed-state energy,\ni.e., to a frequency shift similar to the Bloch-Siegert shift. In particular,\nthis shift is manifested as the dependence of the Rabi-oscillation frequency\n\\epsilon on the sign of the detuning \\omega{1} -\\omega{rf} from resonance. In\nthe case of double resonance, the oscillation amplitude is asymmetric; i.e.,\nthe amplitude at the sum frequency \\omega_{rf} +\\epsilon increases, while the\namplitude at the difference frequency \\omega_{rf} -\\epsilon decreases. The\npredicted effects are confirmed by observations of the nutation signals of the\nelectron paramagnetic resonance (EPR) of centers in quartz and should be taken\ninto account to realize qubits with a low Rabi frequency in solids."
    },
    {
        "anchor": "Memory Function Representation for the Electrical Conductivity of Solids: We derive a formula for the electrical conductivity of solids that includes\nrelaxation, dissipation, and quantum coherence. The derivation is based on the\nKubo formula, with a Mori memory function approach to include dissipation\neffects at all orders in the relaxation interaction. It offers a practical\nmethod to evaluate the conductivity with electronic-structure codes and avoids\nthe complications and limitations of the Kubo formula in the thermodynamic\nlimit. The derivation of our formula provides a method applicable to other\ntransport coefficients and correlation functions.",
        "positive": "The secret harmony of the random disorder, revealed in the paper sheet: This study is about the properties of the sets of objects associated in a\nstructure resulting from multiple-processes involving chance as are materials\nwhose texture is unordered and random. Being a paper scientist the author\nrefers to the sheet of paper which is a stochastic fibrous set whose porous\ntexture can be considered as an archetype for many natural or artificial human\nstructures. The paper properties are correlated with its texture by taking\naccount the effect of chance occurring during its manufacturing process. The\ntheoretical developments, the formalism and the application methods presented\nin this study have a general significance beyond the only paper material.A\nspecific property of sets of objects randomly unorderly distributed in space is\ntheir interfaces orientation distribution. This distribution is usually\nobtained by the analysis of images sampled in the object sets. The density of\norientation probability of the fibers or of the texture interfaces, weighted by\ntheir length or by their area, can be interpreted as the radius of curvature of\nan outline or of a warped surface which characterizes, from a global and\nstatistical point of view, the texture geometry in two or three dimensions.\nThis figure named by the author the \"equivalent pore\", is with its elliptical\nshape similar to the one of the mean pore defined by the mean directional chord\nbetween the interfaces in the texture. Different methods of \"equivalent pore\"\nestablishing are analyzed : by conformal map of the fiber network or of the\ntexture interfaces, by images stereometric analysis of texture tomographical\ncuts, by scattering and diffraction of a laser light beam impacting the fibrous\ntexture or the material surface replica, by hard X-ray absorption and phase\ncontrast at the European Synchrotron Radiation Facilities(ESRF), in Grenoble.\nThe \"equivalent pore\" concept allows us to study random unordered sets behavior\nin strength fields while simplifying this analysis. Thus a phenomenon occurring\nin a plane set, in two dimensions, can be analyzed on its \"equivalent pore\"\nlinear outline, and a phenomenon which occurs in volume in a three dimensional\nset can be analyzed on its \"equivalent pore\" warped surface. This concept has\nbeen applied for physical, mechanical, optical and ionic conduction properties\nof materials like papers, boards, felts, nonwoven textiles, polymer foams,\nmetallic alloys with grain joints, geological grounds, and for the surface\nmapping of natural relief and of materials with different gloss, worn or\nroughness levels.The ellipse and the ellipso\\\"id, as well as multi-modes\ncompositions of it, are the most appropriate figures to represent the\n\"equivalent pore\" of materials with a random unordered texture. The fact that a\nlaw, which defines the curvature of an elliptic deterministic geometrical\nconfiguration, is essential to represent interface orientation allocation of\nelements whose spatial distribution is probabilistic is a noteworthy fact that\nmakes us wonder. This assertion is corroborated by fluid flow analysis through\nporous media. The global dissipated energy for fluid flow is distributed along\nthe motion (translation and rotation) and fluid deformation components on the\n\"equivalent pore\" whose surface is conformal to the texture interfaces\ntangential space. The porous media being homogenous and the fluid particles\nindistinguishable each ones from the others, due to permanent stochastic\nexchanges from one fluid volume element into another, we conclude that their\nmotion quantification is invariant on each point of the \"equivalent pore\"\nsurface. This quantification can be represented by a group of elliptical\ncylinders.The \"equivalent pore\" and cylinders group surface intersections\ndefine the fluid particle probabilistic paths in the porous media. One singular\ngeometrical configuration of the elliptic cylinders group union with the\nellipsoidal \"equivalent pore\" fulfills the minimal energy dissipation\nrequirements in the stress field applied to the fluid. The resulting paths are\nellipso\\\"ido-cylindrical curves carpeting the ellipso\\\"id by a beam of\nisoperim\\'etric lacets, in close or open loops depending on the possible\npairing off the curves in their nodals and isoclinal tangency points. The flow\nlaminarity and unrotationality are globally established in the porous media at\nthe macroscopic scale, for Reynold's number small values, in agreement with the\nresults found moreover. The so defined ellipso\\\"ido-cylindrical curve is a\nstationary curve at the average least action meaning, for a punctual mobile or\na deformable volume element moving on the surface of the ellipsoid from a nodal\nspot to the other in an antipodal position. This curve establishes a gauge\nwhich characterizes, from a global point of view, the physical space embraced\nby the fluid during its flow, in dynamical balance conditions compatible with\nthe stress field. The ellipso\\\"ido-cylindrical curve allows to carpet the\nellipso\\\"id as a function of one cyclic angular variable, which is a new\nconstruction for the ellipso\\\"id. When the set of the objects is isotropic the\ncurve is sphero-cylindrical whose plan mapping permit to decipher the tai-chi\nfigure of the Tao\\\"ist Buddhism philosophy.This study of random unordered\nobject sets, and more specially of fibrous porous media, allows to establish a\nstructural link between their small scale texture stochastic disorder and the\nharmonious order that emerges from these sets at a larger scale. The largest\nchance possible, compatible with the stress field which put a strain on these\nsets, is the necessary and sufficient variable which allows to best globally\nadjust their behaviors according to the probabilistic and deterministic laws\ngoverning their evolution.The vocabulary used in this study is issued from the\ncommon language, most of the time adapted to the material class, it is\ntransposable in other fields of interest. The text is completed by notes and a\nbibliography which refer to the works done following the presented concepts or\nin relation to this field of studies."
    },
    {
        "anchor": "Modulational instability of a recent nonlinear plasmonic metamaterial:\n  Finite-difference-time-domain simulations: By doing time-domain simulations, we find the proposal for\nnegative-to-positive index switching proposed in [Physical Review Letters, 106\n105503 (2012)] may be fragile. The negative opinion on the uniform switching of\nlocal optical constants in our recent paper [arXiv:1111.1476v2] based on the\ncircuit model of metamaterials can therefore be verified in this specific and\nrealistic case.",
        "positive": "Polarization-induced Rashba spin-orbit coupling in structurally\n  symmetric III-Nitride quantum wells: The effective linear coupling coefficient and the total spin-splitting are\ncalculated in Ga- and N- face InGaN quantum wells. Alloy content, geometry, and\ngate voltage affect an internal field and an electron density distribution in\nthe growth direction that has direct effect on a spin-splitting. The sign of\nstructural inversion asymmetry (SIA) spin-orbit coupling coefficient depends on\nan internal electric field in the well that results in different signs for\nGa-face and N-face III-Nitride structures. The effective linear coupling\ncoefficient is always positive because of the Dresselhaus-type contribution\nthat is a major one in quantum wells under consideration. The magnitude of the\nspin-splitting is comparable with that experimentally observed in III-Nitrides\nand III-V zinc-blende structures."
    },
    {
        "anchor": "Electric field control of Jahn-Teller distortions in bulk perovskites: The Jahn-Teller distortion, by its very nature, is often at the heart of the\nvarious electronic properties displayed by perovskites and related materials.\nDespite the Jahn-Teller mode being non- polar in nature, we devise and\ndemonstrate in the present letter an electric field control of Jahn-Teller\ndistortions in bulk perovskites. The electric field control is enabled through\nan anharmonic lattice mode coupling between the Jahn-Teller distortion and a\npolar mode. We confirm this coupling, and explicitly an electric field effect,\nthrough first principles calculations. The coupling will always exist within\nthe P b2 1 m space group, which is found to be the favoured ground state for\nvarious perovskites under sufficient tensile epitaxial strain. Intriguingly,\nthe calculations reveal that this mechanism is not only restricted to\nJahn-Teller active systems, promising a general route to tune or induce novel\nelectronic functionality in perovskites as a whole.",
        "positive": "14 Examples of How LLMs Can Transform Materials Science and Chemistry: A\n  Reflection on a Large Language Model Hackathon: Large-language models (LLMs) such as GPT-4 caught the interest of many\nscientists. Recent studies suggested that these models could be useful in\nchemistry and materials science. To explore these possibilities, we organized a\nhackathon.\n  This article chronicles the projects built as part of this hackathon.\nParticipants employed LLMs for various applications, including predicting\nproperties of molecules and materials, designing novel interfaces for tools,\nextracting knowledge from unstructured data, and developing new educational\napplications.\n  The diverse topics and the fact that working prototypes could be generated in\nless than two days highlight that LLMs will profoundly impact the future of our\nfields. The rich collection of ideas and projects also indicates that the\napplications of LLMs are not limited to materials science and chemistry but\noffer potential benefits to a wide range of scientific disciplines."
    },
    {
        "anchor": "Temperature Dependence of Electrical Characteristics of Carbon Nanotube\n  Field-Effect Transistors: A Quantum Simulation Study: By developing a two-dimensional (2D) full quantum simulation, the attributes\nof carbon nanotube field-effect transistors (CNTFETs) in different temperatures\nhave been comprehensively investigated. Simulations have been performed by\nemploying the self-consistent solution of 2D Poisson-Schrodinger equations\nwithin the nonequilibrium Green's function (NEGF) formalism. Principal\ncharacteristics of CNTFETs such as current capability, drain conductance,\ntransconductance, and subthreshold swing (SS) have been investigated.\nSimulation results present that the drain conductance and on-current of the\nCNTFET increases as temperature raises from 250 to 500 K. Meanwhile the\non-/off-current ratio deteriorated due to faster growth in off-current. Also\nthe effects of temperature on short channel effects (SCEs) such as\ndrain-induced barrier lowering (DIBL) and threshold voltage roll-off have been\nstudied. Results show that the subthreshold swing and DIBL parameters are\nalmost linearly correlated, so the degradation of these parameters has the same\norigin and can be perfectly influenced by the temperature.",
        "positive": "Graphene Oxide Photoreduction Recovers Graphene Hot Electron Cooling\n  Dynamics: Reduced graphene oxide (rGO) is a bulk-processable quasi-amorphous 2D\nmaterial with broad spectral coverage and fast electronic response. rGO sheets\nare suspended in a polymer matrix and sequentially photoreduced while measuring\nthe evolving optical spectra and ultrafast electron relaxation dynamics.\nPhotoreduced rGO yields optical absorption spectra that fit with the same Fano\nlineshape parameters as monolayer graphene. With increasing photoreduction\ntime, rGO transient absorption kinetics accelerate monotonically, reaching an\noptimal point that matches the hot electron cooling in graphene. All stages of\nrGO ultrafast kinetics are simulated with a hot-electron cooling model mediated\nby disorder-assisted supercollisions. While the rGO room temperature 0.31\nps$^{-1}$ electronic cooling rate matches monolayer graphene, subsequent\nphotoreduction can rapidly increase the rate by ~10-12$\\times$. Such\naccelerated supercollision rates imply a reduced mean-free scattering length\ncaused by photoionized point-defects on the rGO sp$^2$ sub-lattice. For visible\nrange excitations of rGO, photoreduction shows three increasing spectral peaks\nthat match graphene quantum dot (GQD) transitions, while a broad peak from\noxygenated defect edge states shrinks. These three confined GQD states donate\ntheir hot carriers to the graphene sub-lattice with a 0.17 ps rise-time that\naccelerates with photoreduction. Collectively, many desirable photophysical\nproperties of 2D graphene are replicated through selectively reducing rGO\nscaffolded within a 3D bulk polymeric network."
    },
    {
        "anchor": "Fast computation of the Kohn-Sham susceptibility of large systems: For hybrid systems, such as molecules grafted onto solid surfaces, the\ncalculation of linear response in time dependent density functional theory is\nslowed down by the need to calculate, in N^4 operations, the susceptibility of\nN non interacting Kohn-Sham reference electrons. We show how this\nsusceptibility can be calculated N times faster within finite precision. By\nitself or in combination with previous methods, this should facilitate the\ncalculation of TDDFT response and optical spectra of hybrid systems.",
        "positive": "Forward and Inverse Design of Kirigami via Supervised Autoencoder: Machine learning (ML) methods have recently been used as forward solvers to\npredict the mechanical properties of composite materials. Here, we use a\nsupervised-autoencoder (sAE) to perform inverse design of graphene kirigami,\nwhere predicting the ultimate stress or strain under tensile loading is known\nto be difficult due to nonlinear effects arising from the out-of-plane\nbuckling. Unlike the standard autoencoder, our sAE is able not only to\nreconstruct cut configurations but also to predict mechanical properties of\ngraphene kirigami and classify the kirigami witheither parallel or orthogonal\ncuts. By interpolating in the latent space of kirigami structures, the sAE is\nable to generate novel designs that mix parallel and orthogonal cuts, despite\nbeing trained independently on parallel or orthogonal cuts. Our method allows\nus to both identify novel designs and predict, with reasonable accuracy, their\nmechanical properties, which is crucial for expanding the search space for\nmaterials design."
    },
    {
        "anchor": "Modelling the 0.6 - 0.7 power law of permittivity and admittance\n  frequency responses in random R-C networks: The dielectric response of complex materials is characterized, in many cases,\nby a similar power law frequency dependence of both the real and the imaginary\nparts of their complex dielectric constants. In the admittance representation,\nthis power law is often shown as the constant phase angle (CPA) response.\nApparently, the power that characterizes many different systems, when expressed\nas the frequency dispersion of conductivity (the real part of admittance) is\noften found to be in the range of 0.6 - 0.7 or having frequency independent,\nconstant phase angles (CPA) of about 54 - 63 deg. The model suggested here is\nbased on series-parallel mixing of resistors' and capacitors' responses in a\nrandom R-C network. A geometric mean evaluation of the effective resistivity of\nconductors having a uniform distribution of resistivity is used. In contrast to\nmodels based on percolation arguments, the model suggested here can be applied\nto both 2D and 3D systems.",
        "positive": "Phenomenological theory of the giant magnetoimpedance of composite wires: Composite wires with a three-layered structure are known to show a\nparticularly large magnetoimpedance effect. The wires consist of a highly\nconductive core, an insulating layer and an outer ferromagnetic shell. In order\nto understand the origin of the effect a theory based on a coupling of the\nMaxwell equations to the Landau-Lifschitz-Gilbert equation is suggested. The\ntheory is phenomenological in the sense that it does not account for a domain\nstructure. However, theoretical results nicely reproduce those obtained in\nvarious measurements. Furthermore, an upper limit of the magnetoimpedance ratio\nfor a given combination of materials can be determined."
    },
    {
        "anchor": "Surface plasmon polariton assisted optical switching in noble bimetallic\n  nanoparticle system: Photoresponse of bimetallic Au-Ag nanoparticle embedded soda glass (Au-Ag@SG)\nsubstrate is reported for surface plasmon assisted optical switching using 808\nnm excitation. Au-Ag@SG system is made by an ion beam technique where Ag^+ is\nintroduced first in the soda glass matrix by ion exchange technique.\nSubsequently 400 keV Au^+ is implanted in the sample for different fluences\nwhich is followed by an ion beam annealing process using 1 MeV Si^+ at a fixed\nfluence of 2E16 ions.cm^{-2}. Characteristic surface plasmon resonance (SPR)\npeaks around 400 and 550 nm provided evidence for the presence of Au and Ag\nnanoparticles. An optical switching in the Au-Ag@SG system with 808 nm, which\nis away from the characteristic SPR peaks of Ag and Au nanoparticles, suggests\nthe possible role of TPA owing to the presence of interacting electric dipole\nin these systems. The role of surface plasmon polariton is emphasized for the\npropagation of electronic carrier belonging to the conduction electron of Au-Ag\nsystem in understanding the observed photoresponse. Unique excitation dependent\nphotoresponse measurements confirm the possible role of TPA process. A\ncompetitive interband and intraband transitions in the bimetallic system of Au\nand Ag with may be primarily responsible for the observation, which are\nvalidated qualitatively using finite difference time domain calculations where\ninter-particle separation of Au and Ag play an important role. Thus, a smart\nway of optical switching can be envisaged in noble bimetallic nanocluster\nsystem where long wavelength with higher skin depth can be used for\ncommunication purpose.",
        "positive": "High-field transport and hot electron noise in GaAs from first\n  principles: role of two-phonon scattering: High-field charge transport in semiconductors is of fundamental interest and\npractical importance. While the \\textit{ab initio} treatment of low-field\ntransport is well-developed, the treatment of high-field transport is much less\nso, particularly for multi-phonon processes that are reported to be relevant in\nGaAs. Here, we report a calculation of the high-field transport properties and\ncurrent power spectral density (PSD) of hot electrons in GaAs from first\nprinciples including on-shell two-phonon (2ph) scattering. The on-shell 2ph\nscattering rates are found to qualitatively alter the high-field distribution\nfunction by increasing both the momentum and energy relaxation rates as well as\ncontributing markedly to intervalley scattering. This finding reconciles a\nlong-standing discrepancy regarding the strength of intervalley scattering in\nGaAs as inferred from transport and optical studies. The characteristic\nnon-monotonic trend of PSD with electric field is not predicted at this level\nof theory. Our work shows how \\textit{ab initio} calculations of high-field\ntransport and noise may be used as a stringent test of the electron-phonon\ninteraction in semiconductors."
    },
    {
        "anchor": "Structural, Elastic, Electronic and Optical Properties of a New\n  Layered-Ternary Ta4SiC3 Compound: We propose a new layered-ternary Ta4SiC3 with two different stacking\nsequences ({\\alpha}- and {\\beta}-phases) of the metal atoms along c axis and\nstudy their structural stability. The mechanical, electronic and optical\nproperties are then calculated and compared with those of other compounds M4AX3\n(M = V, Nb, Ta; A = Al, Si and X = C). The predicted compound in the\n{\\alpha}-phase is found to possess higher hardness than any of these compounds.\nThe independent elastic constants of the two phases are also evaluated and the\nresults discussed. The electronic band structures for {\\alpha}- and\n{\\beta}-Ta4SiC3 show metallic conductivity. Ta 5d electrons are mainly\ncontributing to the total density of states (DOS). We see that the\nhybridization peak of Ta 5d and C 2p lies lower in energy and the Ta 5d-C 2p\nbond is stronger than Ta 5d-Si 3p bond. Further an analysis of the different\noptical properties shows the compound to possess improved behavior compared to\nsimilar types of compounds.",
        "positive": "Identifying the critical surface descriptors responsible for the\n  appearance of negative slopes in the adsorption energy scaling relationships: Adsorption energy scaling relationships have now developed beyond their\noriginal form, which was more targeted towards the optimization of catalytic\nsites and the reduction of computational costs in simulations. The recent surge\nof interest in the adsorption energy scaling relations is to explore the\nsurfaces beyond the transition metals (TMs) as well as reactions involving\ncomplicated molecules. Breakdown of such scaling relationships leads to\nmotivating the discovery of novel catalysts with enhanced capabilities. In this\nwork, we report our extensive study on the linear scaling relation (LSR)\nbetween oxygen (O), a group VIA element with elements of neighbouring groups\nsuch as: Group IIIA (Boron (B), Aluminum (Al)), IVA (Carbon (C), Silicon (Si)),\nVA (Nitrogen(N),phosphorus(P)) and VIIA (Florine(F)) on magnetic bimetallic\nsurfaces. We found that the slope is positive for only O versus N and F,\nremaining of the slopes are negative. The present model is based on multiple\nsurface descriptors, particularly spin-averaged d-band center and the surface's\nmagnetic moment, whereas the original scaling theory (Phys. Rev. Lett. 99,\n016105 (2007)) was based on a single adsorbate descriptor: adsorbate valency."
    },
    {
        "anchor": "An Unexpected Role of H During SiC Corrosion in Water: During aqueous corrosion, atoms in the solid react chemically with oxygen,\nleading either to the formation of an oxide film or to the dissolution of the\nhost material. Commonly, the first step in corrosion involves an oxygen atom\nfrom the dissociated water that reacts with the surface atoms and breaks near\nsurface bonds. In contrast, hydrogen on the surface often functions as a\npassivating species. Here, we discovered that the roles of O and H are reversed\nin the early corrosion stages on a Si terminated SiC surface. O forms stable\nspecies on the surface, and chemical attack occurs by H that breaks the Si-C\nbonds. This so-called hydrogen scission reaction is enabled by a newly\ndiscovered metastable bridging hydroxyl group that can form during water\ndissociation. The Si atom that is displaced from the surface during water\nattack subsequently forms H2SiO3, which is a known precursor to the formation\nof silica and silicic acid. This study suggests that the roles of H and O in\noxidation need to be reconsidered.",
        "positive": "Electronic structure investigation of the cubic inverse perovskite\n  Sc3AlN: The electronic structure and chemical bonding of the recently discovered\ninverse perovskite Sc3AlN, in comparison to ScN and Sc metal have been\ninvestigated by bulk-sensitive soft x-ray emission spectroscopy. The measured\nSc L, N K, Al L1, and Al L2,3 emission spectra are compared with calculated\nspectra using first principle density-functional theory including dipole\ntransition matrix elements. The main Sc 3d - N 2p and Sc 3d - Al 3p chemical\nbond regions are identified at -4 eV and -1.4 eV below the Fermi level,\nrespectively. A strongly modified spectral shape of 3s states in the Al L2,3\nemission from Sc3AlN in comparison to pure Al metal is found, which reflects\nthe Sc 3d - Al 3p hybridization observed in the Al L1 emission. The differences\nbetween the electronic structure of Sc3AlN, ScN, and Sc metal are discussed in\nrelation to the change of the conductivity and elastic properties."
    },
    {
        "anchor": "Mesoscale harmonic analysis of homogenous dislocation nucleation: We perform atomistic computer simulations to study the mechanism of\nhomogeneous dislocation nucleation in two dimensional (2D) hexagonal\ncrystalline films during indentation with a circular nanoindenter. The\nnucleation process is governed by the vanishing of the energy associated with a\nsingle normal mode. This critical mode is largely confined to a single plane of\nadjacent atoms. For fixed film thickness, L, the spatial extent, \\xi, of the\ncritical mode grows with indenter radius, R. For fixed R/L, the spatial extent\n\\xi, grows roughly as \\xi ~ L^0.4. We, furthermore, perform a mesoscale\nanalysis to determine the lowest energy normal mode for mesoscale regions of\nvarying radius, r_{meso}, centered on the critical mode's core. The energy,\n\\lambda_{meso}, of the lowest normal mode in the meso-region decays very\nrapidly with r_{meso} and \\lambda_{meso} ~= 0 for r_{meso} >~ \\xi. The lowest\nnormal mode shows a spatial extent, \\xi_{meso}, which has a sublinear power-law\nincrease with r_{meso} for r_{meso} <~ \\xi, and saturates at r_{meso} \\gtrsim\n1.5\\xi. We demonstrate a universal relationship between \\xi_{meso}/ \\xi versus\nr_{meso}/ \\xi: independent of film thickness or indenter radius. The scenario\nthat emerges is one where the analysis of small regions, r_{meso} <~ \\xi, in\nthe material \\emph{can} reveal the presence of incipient instability even when\nthe region being probed is much smaller than the spatial extent of the critical\nmode. However, the mesoscale analysis gives good estimates for the energy and\nspatial extent of the critical mode \\emph{only} for r_{meso} >~ 1.5 \\xi. In\nthis sense homogeneous dislocation nucleation should be understood as a\nquasi-local phenomenon.",
        "positive": "Observation of tunable exchange bias in Sr$_2$YbRuO$_6$: The double perovskite compound, Sr$_{2}$YbRuO$_{6}$, displays reversal in the\norientation of magnetic moments along with negative magnetization due to an\nunderlying magnetic compensation phenomenon. The exchange bias (EB) field below\nthe compensation temperature could be the usual negative or the positive\ndepending on the initial cooling field. This EB attribute has the potential of\ngetting tuned in a preselected manner, as the positive EB field is seen to\ncrossover from positive to negative value above $T_{\\mathrm{comp}}$."
    },
    {
        "anchor": "Metric-wave approach to flexoelectricity within density-functional\n  perturbation theory: Within the framework of density functional perturbation theory (DFPT), we\nimplement and test a novel \"metric wave\" response-function approach. It\nconsists in the reformulation of an acoustic phonon perturbation in the\ncurvilinear frame that is comoving with the atoms. This means that all the\nperturbation effects are encoded in the first-order variation of the real-space\nmetric, while the atomic positions remain fixed. This approach can be regarded\nas the generalization of the uniform strain perturbation of Hamann et al. [D.\nR. Hamann, X. Wu, K. M. Rabe, and D. Vanderbilt, Phys. Rev. B 71, 035117\n(2005)] to the case of inhomogeneous deformations, and greatly facilitates the\ncalculation of advanced electromechanical couplings such as the flexoelectric\ntensor. We demonstrate the accuracy of our approach with extensive tests on\nmodel systems and on bulk crystals of Si and SrTiO$_3$.",
        "positive": "Where Does the Density Localize? Convergent Behavior for Global Hybrids,\n  Range Separation, and DFT+U: Approximate density functional theory (DFT) suffers from many-electron self-\ninteraction error, otherwise known as delocalization error, that may be\ndiagnosed and then corrected through elimination of the deviation from exact\npiecewise linear behavior between integer electron numbers. Although paths to\ncorrection of energetic delocalization error are well- established, the impact\nof these corrections on the electron density is less well-studied. Here, we\ncompare the effect on density delocalization of DFT+U, global hybrid tuning,\nand range- separated hybrid tuning on a diverse test set of 32 transition metal\ncomplexes and observe the three methods to have qualitatively equivalent\neffects on the ground state density. Regardless of valence orbital diffuseness\n(i.e., from 2p to 5p), ligand electronegativity (i.e., from Al to O), basis set\n(i.e., plane wave versus localized basis set), metal (i.e., Ti, Fe, Ni) and\nspin state, or tuning method, we consistently observe substantial charge loss\nat the metal and gain at ligand atoms (ca. 0.3-0.5 e or more). This charge loss\nat the metal is preferentially from the minority spin, leading to increasing\nmagnetic moment as well. Using accurate wavefunction theory references, we\nobserve that a minimum error in partial charges and magnetic moments occur at\nhigher tuning parameters than typically employed to eliminate energetic\ndelocalization error. These observations motivate the need to develop\nmulti-faceted approximate-DFT error correction approaches that separately treat\ndensity delocalization and energetic errors in order to recover both correct\ndensity and magnetization properties."
    },
    {
        "anchor": "Tunable vertical ferroelectricity and domain walls by interlayer sliding\n  in $\u03b2$-ZrI$_{2}$: Vertical ferroelectricity where a net dipole moment appears as a result of\nin-plane ionic displacements has gained enormous attention following its\ndiscovery in transition metal dichalcogenides. Based on first-principles\ncalculations, we report on the evidence of robust vertical ferroelectricity\nupon interlayer sliding in layered semiconducting $\\beta$-ZrI$_{2}$, a sister\nmaterial of polar semimetals MoTe$_{2}$ and WTe$_{2}$. The microscopic origin\nof ferroelectricity in ZrI$_{2}$ is attributed to asymmetric shifts of\nelectronic charges within a trilayer, revealing a subtle interplay of rigid\nsliding displacements and charge redistribution down to ultrathin thicknesses.\nWe further investigate the variety of ferroelectric domain boundaries and\npredict a stable charged domain wall with a quasi-two-dimensional electron gas\nand a high built-in electric field that can increase electron mobility and\nelectromechanical response in multifunctional devices. Semiconducting behaviour\nand a small switching barrier of ZrI$_{2}$ hold promise for novel ferroelectric\napplications, and our results provide important insights for further\ndevelopment of slidetronics ferroelectricity.",
        "positive": "Thermoelectric probe of defect state induced by ionic liquid gating in\n  vanadium dioxide: Thermoelectric measurements detect the asymmetry between the density of\nstates above and below the chemical potential in a material. It provides\ninsights into small variations in the density of states near the chemical\npotential, complementing electron transport measurements. Here, combined\nresistance and thermoelectric power measurements are performed on vanadium\ndioxide (VO2), a prototypical correlated electron material, under ionic-liquid\n(IL) gating. With IL gating, charge transport below the\nmetal-to-insulator-transition (MIT) temperature remains in the thermally\nactivated regime, while the Seebeck coefficient exhibits an apparent transition\nfrom semiconducting to metallic behavior. The contrasting behavior indicates\nchanges in electronic structure upon IL gating, due to the formation of oxygen\ndefect states. The experimental results are corroborated by numerical\nsimulations based on a model density of states incorporating a gating induced\ndefect band. This study reveals thermoelectric measurements to be a convenient\nand sensitive probe for the role of defect states induced by IL gating in\nsuppressing the MIT in VO2, which remains benign in charge transport\nmeasurements, and possibly for studying defect sates in other materials."
    },
    {
        "anchor": "Can the structure of amorphous indium gallium zinc oxide be described in\n  terms of a few polyhedral motifs?: The coordination polyhedra around the cations are the building blocks of\nionic solids. In context of amorphous InGaZn oxide (a-IGZO), even though the\ncoordination polyhedra are irregularly arranged, it will be beneficial to\nidentify them. In this work, we address the questions, (a) is it possible to\nclassify all the polyhedra that occur in a-IGZO into only a few distinct\ngroups? and (b) are these the same polyhedral motifs as those observed in the\ncrystalline indium gallium zinc oxide (c-IGZO) or other related crystalline\noxides of indium, gallium and zinc? Therefore, in this first principles based\nstudy, a large number (ten) of equivalent samples of a-IGZO were prepared by ab\ninitio melt-and-quench molecular dynamics, so that several distinct samples of\nthe amorphous landscape are obtained. The combination of all these structures\nthus obtained is a better representation of a real a-IGZO sample. For the ten\nsamples containing 360 cations, we propose a simpler and more accurate method\nfor determining the coordination number of each polyhedron, which was verified\nby charge density plots. Based on a method of comparing bond angles between\nmetal and oxygen atoms, the identified polyhedra were matched to the polyhedral\nmotifs present in the related crystalline systems, such as, InGaZnO4, In2O3,\nGa2O3 and ZnO. We find, the a-IGZO primarily consists of the following\npolyhedra: a tetrahedron from space group 199 and an octahedron from space\ngroup 206 of In2O3; a tetrahedron from space group 12 and an octahedron from\nspace group 167 of Ga2O3; a tetrahedron from space group 186 of ZnO; zinc and\ngallium trigonal bipyramids from c-IGZO; and one zinc 4-fold, one zinc 5-fold\nand one indium 5-fold coordination polyhedra that occur only in the amorphous\nphase. We are able to reduce the description of structure from 360 to 10 groups\nof polyhedra. The benefits of this identification could be enormous.",
        "positive": "Pressure tunable magnetic skyrmion phase in Co8Zn8Mn4 single crystals: In a magnetic skyrmion phase, magnetic moments form vortex-like topological\ntextures which are of both fundamental and industrial interests. In\n$\\beta$-Mn-type Co-Zn-Mn alloys, chrial magnetic skyrmions emerge above room\ntemperature, providing a unique system for studying the skrymion physics and\nexploring spintronics applications. However, the magnetic skyrmion phase is\ntypically confined in a narrow and limited temperature ($T$) and magnetic field\n($H$) range. Here, we demonstrate that hydrostatic pressure can expand the\nskyrmion phase in the $T-H$ phase diagram of single-crystalline\nCo$_8$Zn$_8$Mn$_4$. At ambient pressure, signatures of skyrmions are seen\nwithin $T\\sim302-308$ K and $H\\sim50-100$ Oe. Applying a moderate pressure of 6\nkbar extends this range to $T\\sim300-310$ K and $H\\sim50-150$ Oe. However,\nfurther escalation of pressure to 10 kbar results in a slight contraction of\nthe skyrmion phase. These findings underscore the sensitivity of the skyrmion\nphase in Co$_8$Zn$_8$Mn$_4$ to external pressures, and hint at the potential of\nstrain engineering, particularly in $\\beta$-Mn-type Co-Zn-Mn thin films, as a\npromising avenue to customize the skyrmion phase."
    },
    {
        "anchor": "The healing mechanism for excited molecules near metallic surfaces: Radiation damage prevents the ability to obtain images from individual\nmolecules. We suggest that this problem can be avoided for organic molecules by\nplacing them in close proximity with a metallic surface. The molecules will\nthen quickly dissipate any electronic excitation via their coupling to the\nmetal surface. They may therefore be observed for a number of elastic\nscattering events that is sufficient to determine their structure.",
        "positive": "Au-Assisted Substrate-Faceting for Inclined Nanowire Growth: We study the role of gold droplets in the initial stage of nanowire growth\nvia the vapor liquid solid method. Apart from serving as a collections center\nfor growth species, the gold droplets carry an additional crucial role that\nnecessarily precedes the nanowire emergence, that is, they assist the\nnucleation of nanocraters with strongly faceted 111B side walls. Only once\nthese facets become sufficiently large and regular, the gold droplets start\nnucleating and guiding the growth of nanowires. We show that this dual role of\nthe gold droplets can be detected and monitored by high energy electron\ndiffraction during growth. Moreover, gold induced formation of craters and the\nonset of nanowires growth on the 111B facets inside the craters are confirmed\nby the results of Monte Carlo simulations. The detailed insight into the growth\nmechanism of inclined nanowires will help to engineer new and complex nanowire\nbased device architectures."
    },
    {
        "anchor": "Thermal and Vibrational Properties of Thermoelectric ZnSb - Exploring\n  the Origin of Low Thermal Conductivity: The intermetallic compound ZnSb is an interesting thermoelectric material,\nlargely due to its low lattice thermal conductivity. The origin of the low\nthermal conductivity has so far been speculative. Using multi-temperature\nsingle crystal X-ray diffraction (9 - 400 K) and powder X-ray diffraction (300\n- 725 K) measurements we characterized the volume expansion and the evolution\nof structural properties with temperature and identify an increasingly\nanharmonic behavior of the Zn atoms. From a combination of Raman spectroscopy\nand first principles calculations of phonons we consolidate the presence of\nlow-energy optic modes with wavenumbers below 60 cm-1. Heat capacity\nmeasurements between 2 and 400 K can be well described by a Debye-Einstein\nmodel containing one Debye and two Einstein contributions with temperatures\n{\\Theta}D = 195K, {\\Theta}E1 = 78 K and {\\Theta}E2 = 277 K as well as a\nsignificant contribution due to anharmonicity above 150 K. The presence of a\nmultitude of weakly dispersed low-energy optical modes (which couple with the\nacoustic, heat carrying phonons) combined with anharmonic thermal behavior\nprovides an effective mechanism for low lattice thermal conductivity. The\npeculiar vibrational properties of ZnSb are attributed to its chemical bonding\nproperties which are characterized by multicenter bonded structural entities.\nWe argue that the proposed mechanism to explain the low lattice thermal\nconductivity of ZnSb might also control the thermoelectric properties of\nelectron poor semiconductors, such as Zn4Sb3, CdSb, Cd4Sb3, Cd13-xInyZn10, and\nZn5Sb4In2-x.",
        "positive": "Electrical transport and ferromagnetism in Ga1-xMnxAs synthesized by ion\n  implantation and pulsed-laser melting: We present a detailed investigation of the magnetic and magnetotransport\nproperties of thin films of ferromagnetic Ga1-xMnxAs synthesized using ion\nimplantation and pulsed-laser melting (II-PLM). The field and\ntemperature-dependent magnetization, magnetic anisotropy, temperature-dependent\nresistivity, magnetoresistance, and Hall effect of II-PLM Ga1-xMnxAs films have\nall of the characteristic signatures of the strong p-d interaction of holes and\nMn ions observed in the dilute hole-mediated ferromagnetic phase. The\nferromagnetic and electrical transport properties of II-PLM films correspond to\nthe peak substitutional Mn concentration meaning that the non-uniform Mn depth\ndistribution is unimportant in determining the film properties. Good\nquantitative agreement is found with films grown by low temperature molecular\nbeam epitaxy (LT-MBE) and having the similar substitutional Mn_Ga composition.\nAdditionally, we demonstrate that II-PLM Ga1-xMnxAs films are free from\ninterstitial Mn_I because of the high temperature processing. At high Mn\nimplantation doses the kinetics of solute redistribution during solidification\nalone determine the maximum resulting Mn_Ga concentration. Uniaxial anisotropy\nbetween in-plane [-110]and [110] directions is present in II-PLM Ga1-xMnxAs\ngiving evidence for this being an intrinsic property of the carrier-mediated\nferromagnetic phase."
    },
    {
        "anchor": "Competing jump cycles for vacancy diffusion in binary alloys: The mean-first-passage-times (MFPTs) for a vacancy that diffuses (via one-\nand six-jump cycles) in a two dimensional ordered binary alloy are evaluated\nusing the properties of random walks on networks. We investigate the effect of\ntemperature and relative barrier height on the ratio between the MFPTs of the\ntwo cycles. We find that the six-jump cycle takes shorter time than the\none-jump cycle for the range of parameters considered.",
        "positive": "Machine Learning-based estimation and explainable artificial\n  intelligence-supported interpretation of the critical temperature from\n  magnetic ab initio Heusler alloys data: Machine Learning (ML) has impacted numerous areas of materials science, most\nprominently improving molecular simulations, where force fields were trained on\npreviously relaxed structures. One natural next step is to predict material\nproperties beyond structure. In this work, we investigate the applicability and\nexplainability of ML methods in the use case of estimating the critical\ntemperature for magnetic Heusler alloys calculated using ab initio methods\ndetermined materials-specific magnetic interactions and a subsequent Monte\nCarlo (MC) approach. We compare the performance of regression and\nclassification models to predict the range of the critical temperature of given\ncompounds without performing the MC calculations. Since the MC calculation\nrequires computational resources in the same order of magnitude as the\ndensity-functional theory (DFT) calculation, it would be advantageous to\nreplace either step with a less computationally intensive method such as ML. We\ndiscuss the necessity to generate the magnetic ab initio results to make a\nquantitative prediction of the critical temperature. We used state-of-the-art\nexplainable artificial intelligence (XAI) methods to extract physical relations\nand deepen our understanding of patterns learned by our models from the\nexamined data."
    },
    {
        "anchor": "Determine the chirality of Weyl fermions from the circular dichroism\n  spectra of time-dependent ARPES: We show that the intensity of pumped states near Weyl point is different when\npumped with left- and right-handed circular polarized light, which leads to a\nspecial circular dichroism (CD) in time-dependent angle resolved photoemission\nspectra (ARPES). We derive the expression for the CD of time-dependent ARPES,\nwhich is directly related to the chirality of Weyl fermions. Based on the above\nderivation, we further propose a method to determine the chirality for a given\nWeyl point from the CD of time-dependent ARPES. The corresponding CD spectra\nfor TaAs has then been calculated from the first principle, which can be\ncompared with the future experiments.",
        "positive": "Dielectric relaxation induced by oxygen vacancies in\n  Na$_{0.5}$Bi$_{0.5}$TiO$_{3}$ ceramics: Dielectric permittivity was studied in ceramics of relaxor ferroelectric\nbismuth-sodium titanate Na$_{0.5}$Bi$_{0.5}$TiO$_{3}$. The measurements were\nperformed on as sintered and heat treated in vacuum samples. The diffuse\ndielectric anomalies associated with the structural phase transitions were\nobserved in as sintered samples. The intense peak of permittivity ($\n\\varepsilon_{\\text{max}} \\sim 10^{4}$) appeared after heat treating in vacuum.\nThe anomaly of $\\varepsilon(T)$ was contributed by slow polarization processes\n($f<10$ kHz) and was non-stable, vanishing on heating in air up to $\\sim 800$\nK. Temperature and frequency dependencies of $\\varepsilon$ were described by\nusing Cole-Cole model with accounting thermally stimulated decay of the\nnon-stable polarization. It is supposed that the dielectric anomaly is\ndetermined by space charge polarization mechanism. Oxygen vacancies\nV$_{\\rm{O}}^{\\bullet \\bullet}$ and electrons localized on titanium ions\nTi$'_{\\rm{Ti}}$\n  are assumed to be responsible for the phenomenon observed."
    },
    {
        "anchor": "DNA Nanorobotics: This paper presents a molecular mechanics study for new nanorobotic\nstructures using molecular dynamics (MD) simulations coupled to virtual reality\n(VR) techniques. The operator can design and characterize through molecular\ndynamics simulation the behavior of bionanorobotic components and structures\nthrough 3-D visualization. The main novelty of the proposed simulations is\nbased on the mechanical characterization of passive/active robotic devices\nbased on double stranded DNA molecules. Their use as new DNA-based nanojoint\nand nanotweezer are simulated and results discussed.",
        "positive": "Structure and magnetic properties of melilite-type compounds RE2Be2GeO7\n  (RE = Pr, Nd, Gd-Yb) with Rare-Earth ions on Shastry-Sutherland lattice: Rare-earth (RE) based frustrated magnets as typical systems of combining\nstrong spin-orbit coupling, geometric frustration and anisotropic exchange\ninteractions, can give rise to diverse exotic magnetic ground states such as\nquantum spin liquid (QSL). The discovery of new RE-based frustrated materials\nis crucial for exploring the exotic magnetic phases. Herein, we report the\nsynthesis, structure and magnetic properties of a family of melilite-type\nRE2Be2GeO7 (RE = Pr, Nd, Gd-Yb) compounds crystallized in a tetragonal\nstructure, where magnetic RE3+ ions lay out on Shastry-Sutherland lattice (SSL)\nwithin ab-plane and are well separated by nonmagnetic GeBe2O7 polyhedrons along\nc-axis. Temperature-dependent susceptibilities and isothermal magnetization\nM(H) measurements reveal that most RE2Be2GeO7 compounds except RE=Tb show no\nmagnetic ordering down to 2 K despite the dominant antiferromagnetic (AFM)\ninteractions, where Tb2Be2GeO7 undergoes AFM transition with Neel temperature\nTN~ 2.5 K and field-induced spin flop behaviors (T< TN). In addition, the\ncalculated magnetic entropy change from the isothermal M(H) curves reveal a\nviable magnetocaloric effect (MCE) for RE2Be2GeO7 (RE =Gd, Dy) in liquid helium\ntemperature regimes, Gd2Be2GeO7 shows maximum Sm up to 54.8 J K-1 Kg-1 at H= 7\nT and Dy2Be2GeO7 has largest value Sm=16.1 J K-1 kg-1 at H= 2 T in this family.\nMore excitingly, rich diversity of RE ions in this family enables an archetype\nfor exploring exotic quantum magnetic phenomena with large variability of spin\nlocated on SSL lattice."
    },
    {
        "anchor": "Development of hard water sensor using Fluorescence Resonance Energy\n  Transfer: A method is presented for the sensing of water hardness by determining the\nconcentration of calcium and magnesium in water, based on Fluorescence\nresonance energy transfer (FRET) process. The principle of the proposed sensor\nis based on the change of FRET efficiency between two laser dyes Acriflavine\n(Acf) and Rhodamine B (RhB) in presence of permanent hard water components\n(CaCl2 and MgCl2). Nanodimensional clay platelet laponite was used to enhance\nthe efficiency of the sensor.",
        "positive": "Mapping of Low-Frequency Raman Modes in CVD-Grown Transition Metal\n  Dichalcogenides: Layer Number, Stacking Orientation and Resonant Effects: Layered inorganic materials, such as the transition metal dichalcogenides\n(TMDs), have attracted much attention due to their exceptional electronic and\noptical properties. Reliable synthesis and characterization of these materials\nmust be developed if these properties are to be exploited. Herein, we present\nlow-frequency Raman analysis of MoS2, MoSe2, WSe2 and WS2 grown by chemical\nvapour deposition (CVD). Raman spectra are acquired over large areas allowing\nchanges in the position and intensity of the shear and layer-breathing modes to\nbe visualized in maps. This allows detailed characterization of mono- and\nfew-layered TMDs which is complementary to well-established (high-frequency)\nRaman and photoluminescence spectroscopy. This study presents a major stepping\nstone in fundamental understanding of layered materials as mapping the\nlow-frequency modes allows the quality, symmetry, stacking configuration and\nlayer number of 2D materials to be probed over large areas. In addition, we\nreport on anomalous resonance effects in the low-frequency region of the WS2\nRaman spectrum."
    },
    {
        "anchor": "Expression and interactions of stereo-chemically active lone pairs and\n  their relation to structural distortions and thermal conductivity: Stereo-chemically active lone pairs are typically described as an important\nnon-bonding effect, and large interest has centered on understanding the\nderived effect of lone pair expression on physical properties such as the\nthermal conductivity. To manipulate such properties, it is essential to\nunderstand the conditions that lead to lone pair expression and to provide a\nquantitative chemical description. Here we first use density functional theory\ncalculations to establish the presence of stereo-chemically active lone pairs\non antimony in $\\text{MnSb}_{2}\\text{O}_{4}$. The lone pairs are formed through\na similar mechanism to those in binary post-transition metal compounds in an\noxidation state of two less than their main group number, where the degree of\norbital interaction determines the expression of the lone pair. In\n$\\text{MnSb}_{2}\\text{O}_{4}$ the Sb lone pairs interact through a void space\nin the crystal structure, and they minimize their mutual repulsion by\nintroducing a deflection angle. This angle increases significantly with\ndecreasing Sb-Sb distance, thus showing the highly destabilizing nature of the\nlone pair interactions. Analysis of the chemical bonding in the structure shows\nthat it is dominated by polar covalent interactions. A database search of\nrelated ternary chalcogenide structures shows that for structures with a lone\npair the degree of lone pair expression is largely determined by whether the\nantimony-chalcogen units are connected or not, suggesting a cooperative effect.\nIsolated $\\text{SbX}_3$ units have larger X-Sb-X bond angles, and therefore\nweaker lone pair expression than connected units. Since increased lone pair\nexpression is equivalent to an increased orbital interaction (covalent\nbonding), which typically leads to increased heat conduction, this can explain\nthe previously established correlation between larger bond angles and lower\nthermal conductivity.",
        "positive": "A Fully Coupled Multi-Physics Model to Simulate Phase Change Memory\n  Operations in Ge-rich Ge$_2$Sb$_2$Te$_5$ Alloys: A self-consistent model for the simulation of Ge-rich Ge$_2$Sb$_2$Te$_5$\nphase change memories is presented. Combining the multi-phase field model and a\nphase-aware electro-thermal solver, it reproduces the multi-physics behavior of\nthe material. Simulations of memory operations are performed to demonstrate its\nability to reproduce experimental observations."
    },
    {
        "anchor": "Observation of the sliding phason mode of the incommensurate magnetic\n  texture in Fe/Ir(111): The nanoscopic magnetic texture forming in a monolayer of iron on the (111)\nsurface of iridium, Fe/Ir(111), is spatially modulated and uniaxially\nincommensurate with respect to the crystallographic periodicities. As a\nconsequence, a low-energy magnetic excitation is expected that corresponds to\nthe sliding of the texture along the incommensurate direction, i.e., a phason\nmode, which we explicitly confirm with atomistic spin simulations. Using\nscanning tunneling microscopy (STM), we succeed to observe this phason mode\nexperimentally. It can be excited by the STM tip, which leads to a random\ntelegraph noise in the tunneling current that we attribute to the presence of\ntwo minima in the phason potential due to the presence of disorder in our\nsample. This provides the prospect of a floating phase in cleaner samples and,\npotentially, a commensurate-incommensurate transition as a function of external\ncontrol parameters.",
        "positive": "Electrostatics in Periodic Slab Geometries I: We propose a new method to sum up electrostatic interactions in 2D slab\ngeometries. It consists of a combination of two recently proposed methods, the\n3D Ewald variant of Yeh and Berkowitz, J. Chem. Phys. 111 (1999) 3155, and the\npurely 2D method MMM2D by Arnold and Holm, to appear in Chem. Phys. Lett. 2002.\nThe basic idea involves two steps. First we use a three dimensional summation\nmethod whose summation order is changed to sum up the interactions in a\nslab-wise fashion. Second we subtract the unwanted interactions with the\nreplicated layers analytically. The resulting method has full control over the\nintroduced errors. The time to evaluate the layer correction term scales\nlinearly with the number of charges, so that the full method scales like an\nordinary 3D Ewald method, with an almost linear scaling in a mesh based\nimplementation. In this paper we will introduce the basic ideas, derive the\nlayer correction term and numerically verify our analytical results."
    },
    {
        "anchor": "Features of a nano-twist phase in the nanolayered Ti3AlC2 MAX phase: Complex intermetallic materials known as MAX phases exhibit exceptional\nproperties from both metals and ceramics, largely thanks to their nanolayered\nstructure. With high-resolution scanning transmission electron microscopy\nsupported by atomistic modelling, we reveal atomic features of a nano-twist\nphase in the nanolayered \\MAX. The rotated hexagonal single-crystal is\nencompassed within basal symmetric twist interfaces similar to grain\nboundaries. In particular, we show that air-oxidation at \\SI{1000}{\\celsius}\ncan form a twisted phase that leads to the formation of interfacial dislocation\nnetworks with screw characters or to severe interfacial reconstructions.\nAdditionally, we explore the contribution of disclinations to the\nrepresentation by continuum models of the stress field generated by such\nnano-twist defect in the \\MAX{} bulk phase. The occurrence of this unexpected\ndefect is expected to impact the physical response of this nanolayered-based\nmaterial as such supports property-by-design approaches.",
        "positive": "Microscopic structure differences in CZTSe quaternary alloys prepared by\n  different techniques revealed by spatially-resolved\n  laser-induced-modification Raman spectroscopy: While producing comparable efficiencies and showing similar properties when\nprobed by conventional techniques, such as Raman, photoluminescence and X-ray\ndiffraction, two thin film solar cell materials with complex structures, such\nas quaternary compound CZTSe, may in fact differ significantly in their\nmicroscopic structures. In this work, laser induced modification Raman\nspectroscopy, coupled with high spatial resolution and high temperature\ncapability, is demonstrated as an effective tool to obtain important structure\ninformation beyond that the conventional characterization techniques can offer,\nand thus to reveal the microscopic scale variations between nominally similar\nalloys. Specifically, CZTSe films prepared by sputtering and co-evaporation\nmethods that exhibited similar Raman and XRD features were found to behave very\ndifferently under high laser power and high temperature Raman probe, because\nthe differences in their microscopic structures lead to different structure\nmodifications in response to the external stimuli, such as light illumination\nand temperature. They were also shown to undergo different degree of plastic\nchanges and have different thermal conductivities as revealed by\nspatially-resolved Raman spectroscopy."
    },
    {
        "anchor": "Two-dimensional silk: The ability to form silk films on semiconductors, metals, and oxides or as\nfree-standing membranes has motivated research into silk-based electronic,\noptical, and biomedical devices. However, the inherent disorder of native silk\nlimits device performance. Here we report the creation of highly ordered\ntwo-dimensional (2D) silk fibroin (SF) layers on van der Waals solids. Using in\nsitu atomic force microscopy, synchrotron-based infrared spectroscopy, and\nmolecular dynamics simulations, we develop a mechanistic understanding of the\nassembly process. We show that the films consist of lamellae having an\nepitaxial relationship with the underlying lattice and that the SF molecules\nexhibit the same Beta-sheet secondary structure seen in the crystallites of the\nnative form. By increasing the SF concentration, multilayer films form via\nlayer-by-layer growth, either along a classical pathway in which SF molecules\nassemble directly into the lamellae or, at sufficiently high concentrations,\nalong a two-step pathway beginning with formation of a disordered monolayer\nthat subsequently converts into the crystalline phase. Kelvin probe\nmeasurements show that these 2D SF layers substantially alter the surface\npotential. Moreover, the ability to assemble 2D silk on both graphite and MoS2\nsuggests that it may provide a general platform for silk-based electronics on\nvdW solids.",
        "positive": "Photoelectron spectra of anionic sodium clusters from time-dependent\n  density-functional theory in real-time: We calculate the excitation energies of small neutral sodium clusters in the\nframework of time-dependent density-functional theory. In the presented\ncalculations, we extract these energies from the power spectra of the dipole\nand quadrupole signals that result from a real-time and real-space propagation.\nFor comparison with measured photoelectron spectra, we use the ionic\nconfigurations of the corresponding single-charged anions. Our calculations\nclearly improve on earlier results for photoelectron spectra obtained from\nstatic Kohn-Sham eigenvalues."
    },
    {
        "anchor": "Piezoelectric altermagnetism and spin-valley polarization in Janus\n  monolayer $\\mathrm{Cr_2SO}$: The altermagnetism can achieve spin-split bands in collinear\nsymmetry-compensated antiferromagnets. Here, we predict altermagnetic order in\nJanus monolayer $\\mathrm{Cr_2SO}$ with eliminated inversion symmetry, which can\nrealize the combination of piezoelectricity and altermagnetism in a\ntwo-dimensional material, namely 2D piezoelectric altermagnetism. It is found\nthat $\\mathrm{Cr_2SO}$ is an altermagnetic semiconductor, and the spin-split\nbands of both valence and conduction bands are near the Fermi level. The\n$\\mathrm{Cr_2SO}$ has large out-of-plane piezoelectricity ($|d_{31}|$$=$0.97\npm/V), which is highly desirable for ultrathin piezoelectric device\napplication. Due to spin-valley locking, both spin and valley can be polarized\nby simply breaking the corresponding crystal symmetry with uniaxial strain. Our\nfindings provide a platform to integrate spin, piezoelectricity and valley in a\nsingle material, which is useful for multi-functional device applications.",
        "positive": "Observation of a Universal Aggregation Mechanism and a Possible Phase\n  Transition in Au Sputtered by Swift Heavy Ions: Two exponents, $\\delta$, for size distribution of $n$-atom clusters,\n$Y(n)\\sim n^{-\\delta}$, have been found in Au clusters sputtered from embedded\nAu nanoparticles under swift heavy ion irradiation. For small clusters, below\n12.5 nm in size, $\\delta$ has been found to be 3/2, which can be rationalized\nas occurring from a steady state aggregation process with size independent\naggregation. For larger clusters, a $\\delta$ value of 7/2 is suggested, which\nmight come from a dynamical transition to another steady state where\naggregation and evaporation rates are size dependent. In the present case, the\nobserved decay exponents do not support any possibility of a thermodynamic\nliquid-gas type phase transition taking place, resulting in cluster formation."
    },
    {
        "anchor": "Resonant and off-resonant magnetoacoustic waves in epitaxial\n  Fe$_3$Si/GaAs hybrid structures: Surface acoustic waves (SAWs) provide an efficient dynamical coupling between\nstrain and magnetization in micro/nano-metric devices. Using a hybrid device\ncomposed of a piezoelectric, GaAs, and a ferromagnetic Heusler alloy thin film,\nFe$_3$Si, we are able to quantify the amplitude of magnetoacoustic waves\ngenerated with SAWs via magnetic imaging in an X-ray photoelectron microscope.\nThe cubic anisotropy of the sample together with a low damping coefficient\nallows for the observation of resonant and non-resonant magnetoelastic\ncoupling. Additionally, via micromagnetic simulation, we verify the\nexperimental behavior and quantify the magnetoelastic shear strain component in\nFe$_3$Si that appears to be very large ($b_2=14\\times 10^6$ J/m$^3$), much\nlarger than the one found in Nickel.",
        "positive": "Giant oscillatory tunnel magnetoresistance in CoFe/MgO/CoFe(001)\n  junctions: The tunnel magnetoresistance (TMR) effect observed in magnetic tunnel\njunctions (MTJs) is commonly used in many spintronic applications because the\neffect can easily convert from local magnetic states to electric signals in a\nwide range of device resistances. In this study, we demonstrated TMR ratios of\nup to 631% at room temperature (RT), which is two or more times larger than\nthose used currently for magnetoresistive random access memory (MRAM) devices,\nusing CoFe/MgO/CoFe(001) epitaxial MTJs. The TMR ratio increased up to 1143% at\n10 K, which corresponds to an effective tunneling spin polarization of 0.923.\nThe observed large TMR ratios resulted from the fine-tuning of atomic-scale\nstructures of the MTJs, such as crystallographic orientations and MgO interface\noxidation, in which the well-known Delta1 coherent tunneling mechanism for the\ngiant TMR effect is expected to be pronounced. However, behavior that is not\ncovered by the standard coherent tunneling theory was unexpectedly manifested;\ni.e., (i) TMR saturation at a thick MgO barrier region and (ii) enhanced TMR\noscillation with a 0.32 nm period in MgO thickness. Particularly, the TMR\noscillatory behavior dominates the transport in a wide range of MgO\nthicknesses; the peak-to-valley difference of the TMR oscillation exceeded 140%\nat RT, attributable to the appearance of large oscillatory components in\nresistance area product (RA). Further, we found that the oscillatory behaviors\nof the TMR ratio and RA survive, even under a +-1 V bias voltage application,\nindicating the robustness of the oscillation. Our demonstration of the giant\nRT-TMR ratio will be an essential step for establishing spintronic\narchitectures, such as large-capacity MRAMs and spintronic artificial neural\nnetworks. More essentially, the present observations can trigger us to revisit\nthe true TMR mechanism in crystalline MTJs."
    },
    {
        "anchor": "Sensitivity of micromechanical actuation on amorphous to crystalline\n  phase transformations under the influence of Casimir forces: Amorphous to crystalline phase transitions in phase change materials (PCM)\ncan have strong influence on the actuation of microelectromechanical systems\nunder the influence of Casimir forces. Indeed, the bifurcation curves of the\nstationary equilibrium points and the corresponding phase portraits of the\nactuation dynamics between gold and AIST PCM, where an increase of the Casimir\nforce of up ~25% has been measured upon crystallization, show strong\nsensitivity to changes of the Casimir force as the stiffness of the actuating\ncomponent decreases and/or the effective interaction area of the Casimir force\nincreases, which can also lead to stiction. However, introduction of intrinsic\nenergy dissipation (associated with a finite quality factor of the actuating\nsystem) can prevent stiction by driving the system to attenuated motion towards\nstable equilibrium depending on the PCM state and the system quality factor.",
        "positive": "Ab-initio study of electronic and magnetic properties of Mn$_2$RuZ/MgO\n  (001) heterojunctions (Z= Al, Ga, Si, Ge): Using first-principles calculations, we studied Mn$_2$RuZ (Z=Al, Ga, Si, Ge)\nand their heterojunctions with MgO along (001) direction. All these alloys\npossess Hg$_2$CuTi-type inverse Heusler alloy structure and ferrimagnetic\nground state. Our study reveals the half-metallic electronic structure with\nhighly spin-polarized $\\Delta_1$ band, which is robust against atomic disorder.\nNext we studied the electronic structure of Mn$_2$RuAl/MgO and Mn$_2$RuGe/MgO\nheterojunctions. We found that the MnAl- or MnGe-terminated interface is\nenergetically more favorable compared to the MnRu-terminated interface.\nInterfacial states appear at the Fermi level in the minority-spin gap for the\nMn$_2$RuGe/MgO junction. We discuss the origin of these interfacial states in\nterms of local environment around each constituent atom. On the other hand, in\nthe Mn$_2$RuAl/MgO junction, high spin polarization of bulk Mn$_2$RuAl is\npreserved independent of its termination."
    },
    {
        "anchor": "Chemo-mechanical characterization of hydrated Calcium-Hydrosilicates\n  with coupled Raman and nanoindentation measurements: Celitement is a new type of cement that is based on hydraulic\ncalcium-hydrosilicate (hCHS) that possesses a potential for minimizing the\nratio C/S from above 3 in OPC down to 1, which significantly reduces the amount\nof CO$_2$ released during processing. The reaction kinetics of hCHS differs\nfrom that of classical clinker phases due to the presence of highly reactive\nsilicate species, which involve silanol groups instead of pure calcium\nsilicates and aluminates and aluminoferrites. In contrast to Portland cement,\nno calcium hydroxide is formed during hydration, which otherwise regulates the\nCa concentration. Without the buffering role of Ca(OH)$_2$ the concentration of\nthe dissolved species c(Ca$^{2+}$) and c(SiO$_4^{4-}$) and the corresponding pH\nmust be controlled to ensure a reproducible reaction. Pure hCHS reacts\nisochemically with water, resulting in a C-S-H phase with the same chemical\ncomposition as a single hydration product, with a homogeneous distribution of\nthe main elements Ca and Si throughout the sample. Here we study via\nnanoindentation the mechanical properties of two different types of hardened\npastes made out of Celitement (C/S=1.28), with varying amounts of hCHS and\nvariable water to cement ratio. We couple nanoindentation grids with Raman\nmappings to link the nanoscale mechanical properties to individual\nmicrostructural components, yielding in-depth insight into the mechanics of the\nmineralogical phases constituting the hardened cement paste. We show that we\ncan identify in hardened Celitement paste both fresh C-S-H with varying\ndensity, and C-S-H from the raw material using their specific Raman spectra,\nwhile simultaneously measuring their mechanical properties. Albeit not suitable\nfor phase identification, EDX measurements provide valuable information about\nthe distribution of alkalis, thus further helping to understand the reaction\npattern of hCHS.",
        "positive": "Metal Surface Energy: Persistent Cancellation of Short-Range Correlation\n  Effects beyond the Random-Phase Approximation: The role that non-local short-range correlation plays at metal surfaces is\ninvestigated by analyzing the correlation surface energy into contributions\nfrom dynamical density fluctuations of various two-dimensional wave vectors.\nAlthough short-range correlation is known to yield considerable correction to\nthe ground-state energy of both uniform and non-uniform systems, short-range\ncorrelation effects on intermediate and short-wavelength contributions to the\nsurface formation energy are found to compensate one another. As a result, our\ncalculated surface energies, which are based on a non-local\nexchange-correlation kernel that provides accurate total energies of a uniform\nelectron gas, are found to be very close to those obtained in the random-phase\napproximation and support the conclusion that the error introduced by the\nlocal-density approximation is small."
    },
    {
        "anchor": "PyCDT: A Python toolkit for modeling point defects in semiconductors and\n  insulators: Point defects have a strong impact on the performance of semiconductor and\ninsulator materials used in technological applications, spanning\nmicroelectronics to energy conversion and storage. The nature of the dominant\ndefect types, how they vary with processing conditions, and their impact on\nmaterials properties are central aspects that determine the performance of a\nmaterial in a certain application. This information is, however, difficult to\naccess directly from experimental measurements. Consequently, computational\nmethods, based on electronic density functional theory (DFT), have found\nwidespread use in the calculation of point-defect properties. Here we have\ndeveloped the Python Charged Defect Toolkit (PyCDT) to expedite the setup and\npost-processing of defect calculations with widely used DFT software. PyCDT has\na user-friendly command-line interface and provides a direct interface with the\nMaterials Project database. This allows for setting up many charged defect\ncalculations for any material of interest, as well as post-processing and\napplying state-of-the-art electrostatic correction terms. Our paper serves as a\ndocumentation for PyCDT, and demonstrates its use in an application to the\nwell-studied GaAs compound semiconductor. We anticipate that the PyCDT code\nwill be useful as a framework for undertaking readily reproducible calculations\nof charged point-defect properties, and that it will provide a foundation for\nautomated, high-throughput calculations.",
        "positive": "An evaluation of plastic flow stress models for the simulation of\n  high-temperature and high-strain-rate deformation of metals: Phenomenological plastic flow stress models are used extensively in the\nsimulation of large deformations of metals at high strain-rates and high\ntemperatures. Several such models exist and it is difficult to determine the\napplicability of any single model to the particular problem at hand. Ideally,\nthe models are based on the underlying (subgrid) physics and therefore do not\nneed to be recalibrated for every regime of application. In this work we\ncompare the Johnson-Cook, Steinberg-Cochran-Guinan-Lund, Zerilli-Armstrong,\nMechanical Threshold Stress, and Preston-Tonks-Wallace plasticity models. We\nuse OFHC copper as the comparison material because it is well characterized.\nFirst, we determine parameters for the specific heat model, the equation of\nstate, shear modulus models, and melt temperature models. These models are\nevaluated and their range of applicability is identified. We then compare the\nflow stresses predicted by the five flow stress models with experimental data\nfor annealed OFHC copper and quantify modeling errors. Next, Taylor impact\ntests are simulated, comparison metrics are identified, and the flow stress\nmodels are evaluated on the basis of these metrics. The material point method\nis used for these computations. We observe that the all the models are quite\naccurate at low temperatures and any of these models could be used in\nsimulations. However, at high temperatures and under high-strain-rate\nconditions, their accuracy can vary significantly."
    },
    {
        "anchor": "Theoretical demonstration of the possibility of using binary alloys or\n  solid solutions in ternary systems as geothermometers: The investigation of the processes of mineral deposit formation and their\nhistory is a fundamental task. Solving this task can increase mining efficiency\nand make a significant contribution to understanding the formation of the\nEarth's crust. The main approach to solving this task is determining the values\nof thermodynamic functions for phases present in deposits. One of the most\npromising and flexible methods for studying thermodynamic properties is the EMF\nmethod. This article describes the basic principles of the EMF method and\nprovides all possible interpretations of the obtained results. It has also been\ndemonstrated that direct EMF measurements can determine the composition of a\nsolid solution or alloy in a multicomponent system if its EMF dependencies are\nknown. Based on this fact, it can be concluded that any alloy or solid solution\nin a multi-phase association, which undergoes composition changes with\ntemperature and can be quenched, can be used as a geothermometer or\ngeobarometer.",
        "positive": "Multiferroicity and Magnetoelectric Coupling in TbMnO3 Thin Films: In this work, we report the growth and functional characterizations of\nmultiferroic TbMnO3 thin films grown on Nb-doped SrTiO3 (001) substrates using\npulsed laser deposition. By performing detailed magnetic and ferroelectric\nproperties measurements, we demonstrate that the multiferroicity of spin origin\nknown in the bulk crystals can be successfully transferred to TbMnO3 thin\nfilms. Meanwhile, anomalous magnetic transition and unusual magnetoelectric\ncoupling related to Tb moments are observed, suggesting a modified magnetic\nconfiguration of Tb in the films as compared to the bulk counterpart. In\naddition, it is found that the magnetoelectric coupling enabled by Tb moments\ncan even be seen far above the Tb spin ordering temperature, which provides a\nlarger temperature range for the magnetoelectric control involving Tb moments."
    },
    {
        "anchor": "Electronic, vibrational and magnetic properties of a novel C_{48}N_{12}\n  aza-fullerene: We study the structural, electronic, vibrational and magnetic properties of a\nnovel ${\\rm C}_{48}{\\rm N}_{12}$ aza-fullerene using density functional theory\nand restricted Hartree-Fock theory. Optimized geometries and total energy of\nthis fullerene have been calculated. We find that for ${\\rm C}_{48}{\\rm\nN}_{12}$ the total ground state energy is about -67617 eV, the HOMO-LUMO gap is\nabout 1.9 eV, five strong IR spectral lines are located at the vibrational\nfrequencies, 461.5 ${\\rm cm}^{-1}$, 568.4 ${\\rm cm}^{-1}$, 579.3 ${\\rm\ncm}^{-1}$, 1236.1 ${\\rm cm}^{-1}$, 1338.9 ${\\rm cm}^{-1}$, the Raman scattering\nactivities and depolarization ratios are zero, and 10 NMR spectral signals are\npredicted. Calculations of diamagnetic shielding factor, static dipole\npolarizabilities and hyperpolarizabilities of ${\\rm C}_{48}{\\rm N}_{12}$ are\nperformed and discussed.",
        "positive": "Thermodynamic determination of the equilibrium first-order\n  phase-transition line hidden by hysteresis in a phase diagram: Phase diagrams form the basis for the study of material science, and the\nprofiles of phase-transition lines separating different thermodynamic phases\ninclude comprehensive information about thermodynamic quantities, such as\nlatent heat. However, in some materials exhibiting field-induced first-order\ntransitions (FOTs), the equilibrium phase-transition line is hidden by the\nhysteresis region associated with the FOT; thus, it cannot be directly\ndetermined from measurements of resistivity, magnetization, etc. Here, we\ndemonstrate a thermodynamics-based method for determining the hidden\nequilibrium FOT line. This method is verified for the FOT between\nantiferromagnetic and ferrimagnetic states in magneto-electric compounds\n(Fe$_{0.95}$Zn$_{0.05}$)$_{2}$Mo$_{3}$O$_{8}$. The equilibrium FOT line\ndetermined based on the Clausius-Clapeyron equation exhibits a reasonable\nprofile in terms of the third law of thermodynamics, and it shows marked\ndifferences from the midpoints of the hysteresis region. Our findings highlight\nthat care should be taken for referring to the hysteresis midpoint line when\ndiscussing field-induced latent heat or magnetocaloric effects."
    },
    {
        "anchor": "Spin Pumping Driven by Bistable Exchange Spin Waves: Spin pumping driven by bistable exchange spin waves is demonstrated in a\nPt/Y$_3$Fe$_5$O$_{12}$ film under parametric excitation. In the\nPt/Y$_3$Fe$_5$O$_{12}$ film, the spin pumping driven by parametric excitation\nselectively enhances the relaxation of short-wavelength exchange spin waves,\nindicating strong coupling between the exchange spin waves and spin currents at\nthe interface through efficient spin transfer. The parametric spin pumping,\nfurthermore, allows direct access to nonlinear spin wave dynamics in\ncombination with the inverse spin Hall effect, revealing unconventional\nbistability of the exchange spin waves.",
        "positive": "Excitation of spin dynamics by spin-polarized current in vortex state\n  disks: A spin-polarized current with the polarization perpendicular to the plane of\na vortex-state disk results in renormalization of the effective damping for a\ngiven magnetization mode, and the effective damping becomes zero if the current\nexceeds a threshold value. The lowest threshold current corresponds to the\nlowest frequency vortex gyroscopic mode. For larger values of the current the\ndynamic magnetization state is characterized by precession of the vortex around\nthe dot center with non-small amplitude and higher frequency."
    },
    {
        "anchor": "Spin-orbit torques and magnetization switching in Gd/Fe multilayers\n  generated by current injection in NiCu alloys: Light transition metals have recently emerged as a sustainable material class\nfor efficient spin-charge interconversion. We report measurements of\ncurrent-induced spin-orbit torques generated by Ni$_{1-x}$Cu$_{x}$ alloys in\nperpendicularly magnetized ferrimagnetic Gd/Fe multilayers. We show that the\nspin-orbit torque efficiency of Ni$_{1-x}$Cu$_{x}$ increases with the Ni/Cu\natomic ratio, reaching values comparable to those of Pt for Ni$_{55}$Cu$_{45}$.\nFurthermore, we demonstrate magnetization switching of a 20-nm-thick Gd/Fe\nmultilayer with a threshold current that decreases with increasing Ni\nconcentration, similar to the spin-orbit torque efficiency. Our findings show\nthat Ni$_{1-x}$Cu$_{x}$$-$based magnetic heterostructures allow for efficient\ncontrol of the magnetization by electric currents.",
        "positive": "Suppressing The Ferroelectric Switching Barrier in Hybrid Improper\n  Ferroelectrics: Integration of ferroelectric materials into novel technological applications\nrequires low coercive field materials, and consequently, design strategies to\nreduce the ferroelectric switching barriers. In this first principles study, we\nshow that biaxial strain, which has a strong effect on the ferroelectric ground\nstates, can also be used to tune the switching barrier of hybrid improper\nferroelectric Ruddlesden-Popper oxides. We identify the region of the strain --\ntolerance factor phase diagram where this intrinsic barrier is suppressed, and\nshow that it can be explained in relation to strain induced phase transitions\nto nonpolar phases."
    },
    {
        "anchor": "Real-time monitoring of the structure of ultra thin Fe$_3$O$_4$ films\n  during growth on Nb-doped SrTiO$_3$(001): In this work thin magnetite films were deposited on SrTiO$_3$ via reactive\nmolecular beam epitaxy at different substrate temperatures. The growth process\nwas monitored in-situ during deposition by means of x-ray diffraction. While\nthe magnetite film grown at 400$^\\circ$C shows a fully relaxed vertical lattice\nconstant already in the early growth stages, the film deposited at 270$^\\circ$C\nexhibits a strong vertical compressive strain and relaxes towards the bulk\nvalue with increasing film thickness. Furthermore, a lateral tensile strain was\nobserved under these growth conditions although the inverse behavior is\nexpected due to the lattice mismatch of -7.5%. Additionally, the occupancy of\nthe A and B sublattices of magnetite with tetrahedral and octahedral sites was\ninvestigated showing a lower occupancy of the A sites compared to an ideal\ninverse spinel structure. The occupation of A sites decreases for a higher\ngrowth temperature. Thus, we assume a relocation of the iron ions from\ntetrahedral sites to octahedral vacancies forming a deficient rock salt\nlattice.",
        "positive": "Non-proportional response between 0.1-100keV energy by means of highly\n  monochromatic synchrotron X-rays: Using highly monochromatic X-ray synchrotron irradiation ranging from 9 keV\nto 100 keV, accurate Lu2SiO5:Ce3+,Ca (LSO), Lu3Al5O12:Pr3+ (LuAG),\nLu2Si2O7:Ce3+ (LPS) and Gd2SiO5:Ce3+ (GSO) non-proportional response curves\nwere determined. By utilizing information from escape peaks in pulse height\nspectra the response curve can be extended down to several keV. A detailed\nstudy of the non-proportionality just above the K-edge is presented and from\nthat a method, which we named K-dip spectroscopy, is obtained to reconstruct\nthe electron response curve down to energies as low as 100 eV."
    },
    {
        "anchor": "The Role of Carbon Precursor on Boron Carbide Synthesis by Laser-CVD: This paper focuses on the synthesis of rhombohedral B4C (r-B4C) coatings by\nCO2 laser-assisted chemical vapour deposition (LCVD), using a dynamic reactive\natmosphere of BCl3, H2 and CH4 or C2H4. The influence of the carbon precursor\non the deposition kinetics is discussed. The use of ethylene as carbon\nprecursor presents several advantages over the use of methane, which is the\nconventional carbon precursor in CVD processes. These advantages are mainly\nrelated to its high absorption coefficient at the laser wavelength and a higher\nsticking coefficient, which enables to attain higher deposition rates and film\nthickness control at lower carbon precursor concentration. Films with carbon\ncontent from 15 to 22 at.% were grown at a deposition rate as high as 0.12\nmicrometers per second.\n  Keywords: Rhombohedral boron carbide (r-B4C), Laser CVD.",
        "positive": "Change in the Magnetic Domain Alignment Process at the Onset of a\n  Frustrated Magnetic State in Ferrimagnetic La2Ni(Ni1/3Sb2/3)O6 Double\n  Perovskite: We have performed a combined study of magnetization hysteresis loops and time\ndependence of the magnetization in a broad temperature range for the\nferrimagnetic La2Ni(Ni1/3Sb2/3)O6 double perovskite. This material has a\nferrimagnetic order transition at ~100 K and at lower temperatures (~ 20 K)\nshows the signature of a frustrated state due to the presence of two competing\nmagnetic exchange interactions. The temperature dependence of the coercive\nfield shows an important upturn below the point where the frustrated state sets\nin. The use of the magnetization vs. applied magnetic field hysteresis data,\ntogether with the magnetization vs. time data provides a unique opportunity to\ndistinguish between different scenarios for the low temperature regime. From\nour analysis, a strong domain wall pinning results the best scenario for the\nlow temperature regime. For temperatures larger than 20K the adequate scenario\nseems to correspond to a weak domain wall pinning."
    },
    {
        "anchor": "Modeling Defect-Level Switching for Highly-Nonlinear and Hysteretic\n  Electronic Devices: Many semiconductors feature defects with charge state transition levels that\ncan switch due to structure changes following defect ionization: we call this\ndefect-level switching (DLS). For example, DX centers in III-V compounds, and\noxygen vacancies in ZnO, can switch between deep and shallow donor\nconfigurations, and these bistable dynamics are responsible for persistent\nphotoconductivity. We recently demonstrated highly-nonlinear, hysteretic,\ntwo-terminal electronic devices using DLS in CdS [H. Yin, A. Kumar, J.M.\nLeBeau, and R. Jaramillo, Phys. Rev. Applied 15, 014014 (2021).] The resulting\ndevices operate without mass transport, and in the opposite sense to most\nresistive switches: they are in a high-conductivity state at equilibrium, and\nswitch to a low-conductivity state at forward bias. Although DLS uses the same\ndefect transitions that are responsible for persistent photoconductivity, DLS\ndevices operate without light and can be orders-of-magnitude faster due to\nexponential tuning of transition rates with voltage. In this work we use theory\nand numerical simulation to explore the design space of DLS devices,\nemphasizing the tradeoff between speed and on/off ratio. Our results will be\nuseful to guide future applications of these unusual devices.",
        "positive": "Fabrication, optical characterization and modeling of strained\n  core-shell nanowires: Strained nanowires with varying InAs/InP core-shell thicknesses were grown\nusing Chemical Beam Epitaxy. Microphotoluminescence spectroscopy, performed at\nlow temperature, was then used to study the optical properties of single wires.\nEmission from the InAs core was observed and its dependence on the shell\nthickness/core diameter ratio was investigated. We found that it is possible to\ntune the emission energy towards 0.8 eV by controlling this ratio. We have\ncompared the measured energies with calculated energies. Our findings are\nconsistent with the wires having a hexagonal crystal structure."
    },
    {
        "anchor": "Physical mechanisms affecting critical angle for nanopatterning in\n  irradiated thin films: I. A composite model: Ion-beam irradiation of an amorphizable material such as Si or Ge may lead to\nspontaneous pattern formation, rather than flat surfaces, for irradiation\nbeyond some critical angle against the surface normal. It is observed\nexperimentally that this critical angle varies according to many factors,\nincluding beam energy, ion species and target material. In this first part of a\nset of papers, we consider a composite model of stress-free strain and\nisotropic swelling with a generalized treatment of stress modification along\nidealized ion tracks. We obtain a highly-general linear stability result with a\ncareful treatment of arbitrary depth-dependence profiles for each of the\nstress-free strain-rate tensor, a source of deviatoric stress modification, and\nisotropic swelling, a source of isotropic stress. We compare our theoretical\nresults with experimental measurements of angle-dependent deviatoric and\nisotropic stresses for 250eV Ar+ on Si. Our analysis suggests that the presence\nof angle-independent isotropic stress and the relationship between the\namorphous-crystalline and free interfaces may be strong contributors to\ncritical angle selection, while the influence of inhomogeneous stress\nmodification is seemingly non-existent in the idealized case of\ndiagonally-translated interface and stress generated entirely along a thin,\ndown-beam ion track. We also consider an opposing idealization: that of\ninterfaces defined by vertical translation, with stress modification along the\nvertical regardless of beam orientation. The unacceptable variability in\npredictions resulting from these two idealizations, both of which have appeared\nin recent analyses, prompts modeling refinements discussed in subsequent papers\nin this set. These refinements include the relationship between interfaces and\na more sophisticated treatment of the inhomogeneous stress field.",
        "positive": "An Enormous Class of Double Half-Heusler Compounds with Low Thermal\n  Conductivity: Since their discovery around a century ago, the structure and chemistry of\nthe multi-functional half-Heusler semiconductors have been studied extensively\nas three component systems. The elemental groups constituting these ternary\ncompounds with the nominal formula XYZ are well established. From the very same\nset of well-known elements we explore a phase space of quaternary double\n($X'X''Y_2Z_2$, $X_2Y'Y''Z_2$, and $X_2Y_2Z'Z''$), triple ($X_2'X''Y_3Z_3$) and\nquadruple ($X_3'X''Y_4Z_4$) half-Heusler compositions which 10 times larger in\nsize. Using a reliable, first-principles thermodynamics methodology on a\nselection of 347 novel compositions, we predict 127 new stable quaternary\ncompounds, already more than the 89 reported almost exhaustively for ternary\nsystems. Thermoelectric performance of the state-of-the-art ternary\nhalf-Heusler compounds are limited by their intrinsically high lattice thermal\nconductivity ($\\kappa_{L}$). In comparison to ternary half-Heuslers, thermal\ntransport in double half-Heuslers is dominated by low frequency phonon modes\nwith smaller group velocities and limited by disorder scattering. The double\nhalf-Heusler composition Ti$_2$FeNiSb$_2$ was synthesized and confirmed to have\na significantly lower lattice thermal conductivity (factor of 3 at room\ntemperature) than TiCoSb, thereby providing a better starting point for\nthermoelectric efficiency optimization. We demonstrate a dependable strategy to\nassist the search for low thermal conductivity half-Heuslers and point towards\na huge composition space for implementing it. Our findings can be extended for\nsystematic discovery of other large families of multi-component intermetallic\nsemiconductors."
    },
    {
        "anchor": "Chemical-etch-assisted growth of epitaxial zinc oxide: We use real-time spectroscopic polarimetric observations of growth and a\nchemical model derived therefrom, to develop a method of growing dense,\ntwo-dimensional zinc oxide epitaxially on sapphire by metalorganic chemical\nvapor deposition. Particulate zinc oxide formed in the gas phase is used to\nadvantage as the deposition source. Our real-time data provide unequivocal\nevidence that: a seed layer is required; unwanted fractions of ZnO are\ndeposited; but these fractions can be removed by cycling between brief periods\nof net deposition and etching. The transition between deposition and etching\noccurs with zinc precursor concentrations that only differ by 13%. These\nprocesses are understood by considering the chemistry involved.",
        "positive": "Unusual dynamic susceptibility arising from soft ferromagnetic domains\n  in MnBi8Te13 and Sb-doped MnBi2nTe3n+1 (n=2, 3): MnBi2nTe3n+1(MBT) is the first intrinsic magnetic topological insulator and\nis promising to hostemergent phenomena such as quantum anomalous Hall effect.\nThey can be made ferromagnetic by having n >= 4 or with Sb doping. We studied\nthe magnetic dynamics in a few selected ferromag-netic (FM) MBT compounds,\nincluding MnBi8Te13and Sb doped MnBi2nTe3n+1(n= 2,3) usingAC susceptibility and\nmagneto-optical imaging. Slow relaxation behavior is observed in all\nthreecompounds, suggesting its universality among FM MBT. We attribute the\norigin of the relaxationbehavior to the irreversible domain movements since\nthey only appear below the saturation fieldswhen ferromagnetic domains form.\nThe very soft ferromagnetic domain nature is revealed by thelow-field\nfine-structured domains and high-field sea-urchin-shaped remanent-state domains\nimagedvia our magneto-optical measurements. Finally, we ascribe the rare\n\"double-peak\" behavior ob-served in the AC susceptibility under small DC bias\nfields to the very soft ferromagnetic domainformations."
    },
    {
        "anchor": "Pressure-Induced Phase Transformation in $\u03b2$-Eucryptite: an X-Ray\n  Diffraction and Density Functional Theory Study: Certain alumino-silicates display exotic properties enabled by their\nframework structure made of corner-sharing tetrahedral rigid units. Using\n\\textit{in situ} diamond-anvil cell x-ray diffraction (XRD), we study the\npressure-induced transformation of $\\beta$ eucryptite, a prototypical\nalumino-silicate. $\\beta$ eucryptite undergoes a phase transformation at\nmoderate pressures, but the atomic structure of the new phase has not yet been\nreported. Based on density functional theory stability studies and Rietveld\nanalysis of XRD patterns, we find that the pressure-stabilized phase belongs to\nthe Pna2$_1$ space group. Furthermore, we discover two other possible\npressure-stabilized polymorphs, P1c1 and Pca2$_1$.",
        "positive": "Precipitation of amorphous ferromagnetic semiconductor phase in\n  epitaxially grown Mn-doped Ge thin films: We investigated the origin of ferromagnetism in epitaxially grown Mn-doped Ge\nthin films. Using low-temperature molecular beam epitaxy, Mn-doped Ge films\nwere successfully grown without precipitation of ferromagnetic Ge-Mn\nintermetallic compounds, such as Mn5Ge3. Magnetic circular dichroism\nmeasurements revealed that the epitaxially grown Mn-doped Ge films exhibited\nclear ferromagnetic behavior, but the Zeeman splitting observed at the critical\npoints was not induced by the s,p-d exchange interactions. High-resolution\ntransmission electron microscopy and energy dispersive X-ray spectroscopy\nanalyses show phase separation of amorphous Ge1-xMnx clusters with high Mn\ncontent from a Mn-free monocrystalline Ge matrix. Since amorphous Ge1-xMnx was\ncharacterized as a homogeneous ferromagnetic semiconductor, the precipitation\nof the amorphous Ge1-xMnx clusters is the origin of the ferromagnetic\nsemiconductor behavior of the epitaxially grown Mn-doped Ge films."
    },
    {
        "anchor": "Universal emergence of spatially-modulated structures induced by\n  flexo-antiferrodistortive coupling in multiferroics: We proved the existence of a universal flexo-antiferrodistortive coupling as\na necessary complement to the well-known flexoelectric coupling. The coupling\nis universal for all antiferrodistortive systems and can lead to the formation\nof incommensurate, spatially-modulated phases in multiferroics. Our analysis\ncan provide a self-consistent mesoscopic explanation for a broad range of\nmodulated domain structures observed experimentally in multiferroics.",
        "positive": "One-pot green process to synthesize controllable surface terminations\n  MXenes in molten salts: Surface terminations for 2D MXene have dramatic impacts on physicochemical\nproperties. The commonly etching methods usually introduce -F surface\ntermination or metallic into MXene. Here, we present a new molten salt assisted\nelectrochemical etching (MS-E-etching) method to synthesize fluorine-free\nTi3C2Tx without metallics. Due to performing electrons as reaction agent, the\ncathode reduction and anode etching can be spatially isolated, thus no metallic\npresents in Ti3C2Tx product. Moreover, the Tx surface terminations can be\ndirectly modified from -Cl to -O and/or -S in one pot process. The obtained -O\nterminated MXenes exhibited capacitance of 225 and 205 F/g at 1 and 10 A/g,\nconfirming high reversibility of redox reactions. This one-pot process greatly\nshortens the modification procedures as well as enriches the surface functional\nterminations. More importantly, the recovered salt after synthesis can be\nrecycled and reused, which brands it as a green sustainable method."
    },
    {
        "anchor": "The quasiparticle band gap in the topological insulator Bi2Te3: We present a theoretical study of dispersion of states which form the bulk\nband-gap edges in the three-dimensional topological insulator Bi2Te3. Within\ndensity functional theory, we analyze the effect of atomic positions varying\nwithin the error range of the available experimental data and approximation\nchosen for the exchange-correlation functional on the bulk band gap and k-space\nlocation of valence- and conduction-band extrema. For each set of the positions\nwith different exchange-correlation functionals, we show how many-body\ncorrections calculated within a one-shot GW approach affect the mentioned\ncharacteristics of electronic structure of Bi2Te3. We thus also illustrate to\nwhat degree the one-shot GW results are sensitive to the reference one-particle\nband structure in the case of bismuth telluride. We found that for this\ntopological insulator the GW corrections enlarge the fundamental band gap and\nfor certain atomic positions and reference band structure bring its value in\nclose agreement with experiment.",
        "positive": "Magnetic-induced phonon anisotropy in ZnCr$_2$O$_4$ from first\n  principles: We have studied the influence of magnetic order on the optical phonons of the\ngeometrically frustrated spinel ZnCr$_2$O$_4$ from first-principles. By mapping\nthe first-principles phonon calculations onto a Heisenberg-like model, we\ndeveloped a method to calculate exchange derivatives and subsequently the\nspin-phonon couping parameter from first-principles. All calculations were\nperformed within LSDA+U."
    },
    {
        "anchor": "On semiconductor--metal transition in FeSi induced by ultrahigh magnetic\n  field: At low temperatures, iron monosilicide is a strongly correlated narrow-gap\nsemiconductor. A first order transition to metal state induced by magnetic\nfield was observed for the first time at 355 T in Ref. [Yu. B. Kudasov et al.,\nJETP Lett. 68 (1998) 350]. However, recently a smooth transition from 230 T to\n270 T was found under similar conditions in Ref. [D. Nakamura et al., Phys.\nRev. Lett. 127 (2021) 156601]. This discrepancy goes far beyond experimental\nerrors and deserves a careful study. A methodological analysis of inductive and\nRF techniques of conductivity measurements shows that the difference of these\ncritical magnetic field estimations stems from a divergence in dynamic ranges\nof the techniques. In fact, the above mentioned methods supplement each other.\nThe semiconductor-metal transition under magnetic field in FeSi is a complex\nphenomenon which occurs at the wide range of magnetic fields.",
        "positive": "Electronic and vibrational properties of low-dimensional perovskites\n  Sr$_{1-y}$La$_y$NbO$_{3.5-x}$: By angle-resolved photoemission spectroscopy and polarization-dependent\ninfrared reflectivity measurements the electronic and vibrational properties of\nlow-dimensional perovskites Sr$_{1-y}$La$_y$NbO$_{3.5-x}$ were studied along\ndifferent crystal directions. The electronic behavior strongly depends on the\noxygen and La content, including quasi-one-dimensional metallic and\nferroelectric insulating behavior. An extremely small energy gap at the Fermi\nlevel is found for SrNbO$_{3.41}$ and SrNbO$_{3.45}$ along the conducting\ndirection at low temperature, suggestive for a Peierls-type instability.\nDespite the similar nominal carrier density, for\nSr$_{0.8}$La$_{0.2}$NbO$_{3.50}$ the quasi-one-dimensional metallic character\nis suppressed and no gap opening is observed, which can be explained by\ndifferences in the crystal structure. Electron-phonon interaction appears to\nplay an important role in this series of compounds."
    },
    {
        "anchor": "Phonons, Phase Transitions and Thermal Expansion in LiAlO2: An ab-initio\n  Density Functional Study: We have used ab-initio density functional theory technique to understand the\nphase transitions and structural changes in various high temperature/pressure\nphases of LiAlO2. The electronic band structure as well as phonon spectra are\ncalculated for various phases as a function of pressure. The phonon entropy\nused for the calculations of Gibbs free energy is found to play an important\nrole in the phase stability and phase transitions among various phases. A\nsudden increase in the polyhedral bond lengths (Li/Al-O) signifies the change\nfrom the tetrahedral to octahedral geometry at high-pressure phase transitions.\nThe activation energy barrier for the high-pressure phase transitions is\ncalculated. The phonon modes responsible for the phase transition (upon\nheating) from high pressure phases to ambient pressure phases are identified.\nMoreover, ab-initio lattice dynamics calculations in the framework of\nquasi-harmonic approximations are used to calculate the anisotropic thermal\nexpansion behavior of {\\gamma}-LiAlO2.",
        "positive": "Quantum Octets in Air Stable High Mobility Two-Dimensional PdSe2: Two-dimensional (2D) materials have drawn immense interest in scientific and\ntechnological communities, owing to their extraordinary properties that are\nprofoundly altered from their bulk counterparts and their enriched tunability\nby gating, proximity, strain, and external fields. For digital applications, an\nideal 2D material would have high mobility, air stability, sizable band gap,\nand be compatible with large-scale synthesis. Here we demonstrate air-stable\nfield-effect transistors using atomically thin few-layer PdSe2 sheets that are\nsandwiched between hexagonal BN (hBN), with record high saturation current\n>350{\\mu}A/{\\mu}m, and field effect mobilities 700 and 10,000 cm2/Vs at 300K\nand 2K, respectively. At low temperatures, magnetotransport studies reveal\nunique octets in quantum oscillations, arising from 2-fold spin and 4-fold\nvalley degeneracies, which can be broken by in-plane and out-of-plane magnetic\nfields toward quantum Hall spin and orbital ferromagnetism."
    },
    {
        "anchor": "Many-pole model of inelastic losses in x-ray absorption spectra: Inelastic losses are crucial to a quantitative analysis of x-ray absorption\nspectra. However, current treatments are semi-phenomenological in nature. Here\na first-principles, many-pole generalization of the plasmon-pole model is\ndeveloped for improved calculations of inelastic losses. The method is based on\nthe GW approximation for the self-energy and real space multiple scattering\ncalculations of the dielectric function for a given system. The model retains\nthe efficiency of the plasmon-pole model and is applicable both to periodic and\naperiodic materials over a wide energy range. The same many-pole model is\napplied to extended GW calculations of the quasiparticle spectral function.\nThis yields estimates of multi-electron excitation effects, e.g., the many-body\namplitude factor $S_0^2$ due to intrinsic losses. Illustrative calculations are\ncompared with other GW calculations of the self-energy, the inelastic mean free\npath, and experimental x-ray absorption spectra.",
        "positive": "\"Forbidden\" polarisation and extraordinary piezoelectric effect in\n  organometallic lead halide perovskites: Organometallic lead halide perovskites are highly efficient materials for\nsolar cells and other optoelectronic applications due to their high quantum\nefficiency and exceptional semiconducting properties. A peculiarity of these\nperovskites is the substantial ionic motion under external forces. Here, we\nreveal that electric field-and light-induced ionic motion in MAPbX3 crystals\n(X=Cl, Br, I and MA=CH3NH3) leads to unexpected piezoelectric-like response, an\norder of magnitude larger than in ferroelectric perovskite oxides. The nominal\nmacroscopic symmetry of the crystals is broken by redistribution of ionic\nspecies, which can be controlled deterministically by light and electric field.\nThe revealed piezoelectric response is possibly present in other materials with\nsignificant ionic activity but the unique feature of organometallic perovskites\nis the strong effect on the piezoelectric response of interplay of ionic motion\n(MA+ and X-1) and photoelectrons generated with illumination."
    },
    {
        "anchor": "Structure, physical properties, and magnetically tunable topological\n  phases in topological semimetal EuCuBi: A single material achieving multiple topological phases can provide potential\napplication for topological spintronics, whereas the candidate materials are\nvery limited. Here, we report the structure, physical properties, and possible\nemergence of multiple topological phases in the newly discovered, air-stable\nEuCuBi single crystal. EuCuBi crystallizes in a hexagonal space group P63/mmc\n(No. 194) in ZrBeSi-type structure with an antiferromagnetic (AFM) ground state\nbelow TN = 11.2 K. There is a competition between AFM and ferromagnetic (FM)\ninteractions below TN revealed by electrical resistivity and magnetic\nsusceptibility measurements. With the increasing magnetic field, EuCuBi evolves\nfrom the AFM ground state with a small amount of FM component, going through\ntwo possible metamagnetic phases, finally reaches the field-induced FM phase.\nBased on the first-principles calculations, we demonstrate that the Dirac,\nWeyl, and possible mirror Chern insulator can be achieved in EuCuBi by tuning\nthe temperature and applying magnetic field, making EuCuBi a promising\ncandidate for exploring multiple topological phases.",
        "positive": "Analysis of volume distribution of power loss in ferrite cores: We present a technique to estimate the inhomogeneities of magnetic loss\nacross the section of ferrite cores under ac excitation. The technique is based\non two distinct calorimetric methods that we presented elsewhere. Both methods\nare based on the measurement of the rate of increase of the sample temperature\nunder adiabatic condition. The temperature ramp is recorded either measuring\nthe sample bulk resistivity or using a platinum probe pasted on the sample\nsurface. As an example we apply the procedure to an industrial sample of Mn-Zn\nferrite under controlled sinusoidal excitation with a peak induction of 50 mT\nin the range between 100 kHz and 2 MHz. The results are discussed by comparison\nwith simulations of the dissipation field profile through the sample,\ncalculated using a finite element method (FEM) code."
    },
    {
        "anchor": "Optimal Routes to Ultrafast Polarization Reversal in Ferroelectric\n  LiNbO3: We use the frozen phonon method to calculate the anharmonic potential energy\nsurface and to model the ultrafast ferroelectric polarization reversal in\nLiNbO3 driven by intense pulses of THz light. Before stable switching of the\npolarization occurs, there exists a region of excitation field-strengths where\ntransient switching can occur, as observed experimentally [Physical Review\nLetters 118, 197601 (2017)]. By varying the excitation frequency from 4 to 20\nTHz, our modeling suggests that more efficient, permanent polarization\nswitching can occur by directly exciting the soft mode at 7 THz, compared to\nnonlinear phononic-induced switching driven by exciting a high frequency mode\nat 18 THz. We also show that neglecting anharmonic coupling pathways in the\nmodeled experiment can lead to significant differences in the modeled switching\nfield strengths.",
        "positive": "Comparison of the electrochemical performance of CeO2 and rare\n  earth-based mixed metallic oxide (Ce0.9Zr0.1O2) for supercapacitor\n  applications: CeO2 and Ce0.9Zr0.1O2 are prepared from the sol-gel method to investigate and\ncompare their electrochemical properties for supercapacitor applications.\nStructural, morphological, and elemental studies have been done for CeO2 and\nCe0.9Zr0.1O2 by XRD, SEM, and EDX. Cyclic voltammetry, galvanostatic\ncharge-discharge, and electrochemical impedance spectroscopy techniques are\nused to study the electrochemical performance of these materials. Doping\nenhances the electrochemical performance of the electrode, by improving the\nspecific capacitance (~150%, 243 F g-1 from 96 F g-1) for the doped system @2\nmV s-1 Vs. Ag/AgCl reference electrode in 2 mol L-1 KOH electrolyte solution.\nCe0.9Zr0.1O2 shows only ~30% of capacitance degradation for a ten folds\nincrease in current densities. Ce0.9Zr0.1O2 also shows 16% capacitance\ndegradation after 800 cycles with excellent Columbic efficiency (~100%) @2 A\ng-1 current density. Partial replacement of Ce4+ ion (0.97 {\\AA}) with Zr4+ ion\n(0.84 {\\AA}) results in a decrease in lattice parameter, as confirmed by\nRietveld refinement. Ce0.9Zr0.1O2 has provided good energy, and power density\nof 1.128 Wh kg-1and 112.5 W kg-1 respectively. Furthermore, better diffusivity\nof the Ce0.9Zr0.1O2 in KOH electrolyte (indicated using Randles-Sevcik\nequation-based analysis) is correlated with better electrochemical performance.\nThese insights presented here clearly indicate that Zr doping into CeO2 results\nin a promising candidate material for electrochemical and supercapacitive\napplications."
    },
    {
        "anchor": "Shear-Transformation-Zone Theory of Yielding in Athermal Amorphous\n  Materials: Yielding transitions in athermal amorphous materials resemble critical\nphenomena. Historically, they have been described by the Herschel-Bulkley\nrheological formula, which implies singular behaviors at yield points. In this\npaper, I examine this class of phenomena using an elementary version of the\nthermodynamic shear-transformation-zone (STZ) theory, focusing on the role of\nthe effective disorder temperature, and paying special attention to scaling and\ndimensional arguments. I find a wide variety of Herschel-Bulkley-like\nrheologies but, for fundamental reasons not specific to the STZ theory,\nconclude that the yielding transition is not truly critical. In particular,\nthere is a correlation length that grows rapidly, but ultimately saturates near\nthe yield point.",
        "positive": "Microwave-assisted hydrothermal synthesis of NH4V3O8 microcrystals with\n  controllable morphology: Water-free NH4V3O8 microcrystals have been successfully synthesized by a\nmicrowave-assisted hydrothermal method. The products were characterized by\nmeans of X-ray diffraction, scanning electron microscopy, Fourier transform\ninfrared spectroscopy, thermal gravimetric analysis, cyclic voltammetry, and\ngalvanostatic cycling. The results show phase-pure products whose particle size\nand morphology can be tailored by varying the reaction conditions, i.e.,\nreaction temperature, synthesis duration, and initial pH value. For instance,\nat low pH (2.5 to 3), flower-like agglomerates with primary particles of 20 to\n30 microm length are found, while at pH = 5.5 single microplates with hexagonal\noutline (30 to 40 microm) prevail. The sample with the comparably highest\nspecific surface area (11 m2/g) was studied regarding its electrochemical\nperformance. It shows an extraordinary initial discharge capacity of 378 mA h\ng-1 at 10 mA g-1, which corresponds to the intercalation of 4.2 Li+/f.u."
    },
    {
        "anchor": "Critical heat flux around strongly-heated nanoparticles: We study heat transfer from a heated nanoparticle into surrounding fluid,\nusing molecular dynamics simulations. We show that the fluid next to the\nnanoparticle can be heated well above its boiling point without a phase change.\nUnder increasing nanoparticle temperature, the heat flux saturates which is in\nsharp contrast with the case of flat interfaces, where a critical heat flux is\nobserved followed by development of a vapor layer and heat flux drop. These\ndifferences in heat transfer are explained by the curvature induced pressure\nclose to the nanoparticle, which inhibits boiling. When the nanoparticle\ntemperature is much larger than the critical fluid temperature, a very large\ntemperature gradient develops resulting in close to ambient temperature just\nradius away from the particle surface",
        "positive": "About one application of a complex variable function to investigation of\n  interaction of a dislocation with a pore in powder materials: Interaction of a rectilinear screw dislocation with a parabolic pore is\ndescribed and investigated."
    },
    {
        "anchor": "Effective Hamiltonian of Topological Nodal Line Semimetal in\n  Single-Component Molecular Conductor [Pd(dddt)$_2$] from First-Principles: Using first-principles density-functional theory calculations, we obtain the\nnon-coplanar nodal loop for a single-component molecular conductor\n[Pd(dddt)$_2$] consisting of HOMO and LUMO with different parity. Focusing on\ntwo typical Dirac points, we present a model of an effective 2 $\\times$ 2\nmatrix Hamiltonian in terms of two kinds of velocities associated with the\nnodal line. The base of the model is taken as HOMO and LUMO on each Dirac\npoint, where two band energies degenerate and the off diagonal matrix element\nvanishes. The present model, which reasonably describes the Dirac cone in\naccordance with the first-principles calculation, provides a new method of\nanalyzing electronic states of a topological nodal line semimetal.",
        "positive": "A method for atomistic spin dynamics simulations: implementation and\n  examples: We present a method for performing atomistic spin dynamic simulations. A\ncomprehensive summary of all pertinent details for performing the simulations\nsuch as equations of motions, models for including temperature, methods of\nextracting data and numerical schemes for performing the simulations is given.\nThe method can be applied in a first principles mode, where all interatomic\nexchange is calculated self-consistently, or it can be applied with frozen\nparameters estimated from experiments or calculated for a fixed\nspin-configuration. Areas of potential applications to different magnetic\nquestions are also discussed. The method is finally applied to one situation\nwhere the macrospin model breaks down; magnetic switching in ultra strong\nfields."
    },
    {
        "anchor": "Electrostatics-based finite-size correction for first-principles point\n  defect calculations: Finite-size corrections for charged defect supercell calculations typically\nconsist of image-charge and potential alignment corrections. A wide variety of\nschemes for both corrections have been proposed for decades. Regarding the\nimage-charge correction, Freysoldt, Neugebauer, and Van de Walle (FNV) recently\nproposed a novel method that enables us to accurately estimate the correction\nenergy a posteriori through alignment of the defect-induced potential to the\nmodel charge potential [Freysoldt et al., Phys. Rev. Lett. 102, 016402 (2009)].\nThis method, however, still has two issues in practice. Firstly, it uses\nplanar-averaged potential for determining the potential offset, which cannot be\nreadily applied to relaxed system. Secondly, the long-range Coulomb interaction\nis assumed to be screened by a macroscopic dielectric constant. This is valid\nonly for cubic systems and can bring forth huge errors for defects in\nanisotropic materials. In this study, we use the atomic site electrostatic\npotential as a potential marker instead of the planar-averaged potential, and\nextend the FNV scheme by adopting the point charge model in an anisotropic\nmedium for estimating long-range interactions. We also revisit the conventional\npotential alignment correction and show that it is fully included in the\nimage-charge correction and therefore unnecessary. In addition, we show that\nthe potential alignment corresponds to a part of first-order and full of\nthird-order image-charge correction; thus the third-order image-charge\ncontribution is absent after the potential alignment. Finally, a systematic\nassessment of the accuracy of the extended FNV correction scheme is performed\nfor a wide range of material classes. The defect formation energies calculated\nusing around 100-atom supercells are successfully corrected even after atomic\nrelaxation within a few tenths of eV compared to those in the dilute limit.",
        "positive": "High Curie temperature GaMnAs obtained by resistance-monitored annealing: We show that by annealing Ga1-xMnxAs thin films at temperatures significantly\nlower than in previous studies, and monitoring the resistivity during growth,\nan unprecedented high Curie temperature Tc and conductivity can be obtained. Tc\nis unambiguously determined to be 118 K for Mn concentration x=0.05, 140 K for\nx=0.06, and 120 K for x=0.08. We also identify a clear correlation between Tc\nand the room temperature conductivity. The results indicate that Curie\ntemperatures significantly in excess of the current values are achievable with\nimprovements in growth and post-growth annealing conditions."
    },
    {
        "anchor": "Anomalous electronic transport in Quasicrystals and related Complex\n  Metallic Alloys: We analyze the transport properties in approximants of quasicrystals\nalpha-AlMnSi, 1/1-AlCuFe and for the complex metallic phase lambda-AlMn. These\nphases presents strong analogies in their local atomic structures and are\nrelated to existing quasicrystalline phases. Experimentally they present\nunusual transport properties with low conductivities and a mix of metallic-like\nand insulating-like characteristics. We compute the band structure and the\nquantum diffusion in the perfect structure without disorder and introduce\nsimple approximations that allow to treat the effect of disorder. Our results\ndemonstrate that the standard Bloch-Boltzmann theory is not applicable to these\nintermetallic phases. Indeed their dispersion relation are flat indicating\nsmall band velocities and corrections to quantum diffusion that are not taken\ninto account in the semi-classical Bloch-Boltzmann scheme become dominant. We\ncall this regime the small velocity regime. A simple Relaxation Time\nApproximation to treat the effect of disorder allows us to reproduce the main\nexperimental facts on conductivity qualitatively and even quantitatively.",
        "positive": "Testing the Berry phase model for extraordinary Hall effect in SrRuO3: Recently it has been suggested that the complicated temperature dependence of\nthe extraordinary Hall effect (EHE) in the itinerant ferromagnet SrRuO3 could\nbe explained by the Berry phase effect in the crystal momentum space. We test\nthis model by measurements of EHE as a function of an applied magnetic field at\na constant temperature and show that the results seem to contradict the Berry\nphase mechanism."
    },
    {
        "anchor": "The nature of ferroelectricity under pressure: Advances in first-principles computational approaches have, over the past\nfifteen years, made possible the investigation of physical properties of\nferroelectric systems. In particular, such approaches have led to a microscopic\nunderstanding of the occurrence of ferroelectricity in perovskite oxides at\nambient pressure. In this paper, we report ab-initio studies on the effect of\nhydrostatic pressure on the ferroelectricity in perovskites and related\nmaterials. We found that, unlike commonly believed, these materials exhibit\nferroelectricity at high enough pressure. We also explained in details the\n(unusual) nature of this ferroelectricity.",
        "positive": "Voltage-Controllable Colossal Magnetocrystalline Anisotropy in Single\n  Layer Transition Metal Dichalcogenides: Materials with large magnetocrystalline anisotropy and strong electric field\neffects are highly needed to develop new types of memory devices based on\nelectric field control of spin orientations. Instead of using modified\ntransition metal films, we propose that certain monolayer transition metal\ndichalcogenides are the ideal candidate materials for this purpose. Using\ndensity functional calculations, we show that they exhibit not only a large\nmagnetocrystalline anisotropy (MCA), but also colossal voltage modulation under\nexternal field. Notably, in some materials like CrSe_2 and FeSe_2, where spins\nshow a strong preference for in-plane orientation, they can be switched to\nout-of-plane direction. This effect is attributed to the large band character\nalteration that the transition metal d-states undergo around the Fermi energy\ndue to the electric field. We further demonstrate that strain can also greatly\nchange MCA, and can help to improve the modulation efficiency while combined\nwith an electric field."
    },
    {
        "anchor": "Simultaneous valence shift of Pr and Tb ions at the spin-state\n  transition in ((Pr$_{1-y}$Tb$_{y})_{0.7}$Ca$_{0.3}$CoO$_{3}$: Temperature dependence of the X-ray absorption near-edge structure (XANES)\nspectra at the Pr $L_{3}$- and Tb $L_{3}$-edges was measured for the\n(Pr$_{1-y}$Tb$_{y})_{0.7}$Ca$_{0.3}$CoO$_{3}$ system, in which a\nmetal-insulator (MI) and spin-state (SS) transition took place simultaneously\nat a critical temperature $T_{\\rm MI}$. A small increase in the valence of the\nterbium ion was found below $T_{\\rm MI}$, besides the enhancement of the\npraseodymium valence; the trivalent states, which are stable at room\ntemperature, change to a 3+/4+ ionic mixture at low temperatures. In particular\nfor the $y$=0.2 sample, the average valence determined at 8 K amounts to 3.03+\nand 3.25+ for the Tb and Pr ion, respectively. In analogous\n(Pr$_{1-y}$RE$_{y})_{0.7}$Ca$_{0.3}$CoO$_{3}$ samples (RE=Sm and Eu), in which\nthe MI-SS transition also took place, no valence shift of the RE ion was\ndetected in the XANES spectra at the RE ion $L_{3}$-edge. The role of the\nsubstituted RE ion for the Pr-site on the MI-SS transition is discussed.",
        "positive": "Full Electrical Control of the Electron Spin Relaxation in GaAs Quantum\n  Wells: The electron spin dynamics in (111)-oriented GaAs/AlGaAs quantum wells is\nstudied by timeresolved photoluminescence spectroscopy. By applying an external\nfield of 50 kV/cm a two-order of magnitude increase of the spin relaxation time\ncan be observed reaching values larger than 30 ns; this is a consequence of the\nelectric field tuning of the spin-orbit conduction band splitting which can\nalmost vanish when the Rashba term compensates exactly the Dresselhaus one. The\nmeasurements under transverse magnetic field demonstrate that the electron spin\nrelaxation time for the three space directions can be tuned simultaneously with\nthe applied electric field."
    },
    {
        "anchor": "Floating Tip Nanolithography: We demonstrate noncontact, high quality surface modification with spatial\nresolution of ~20 nm. The nanowriting is based on the interaction between the\nsurface and the tip of an Atomic force microscope illuminated by a focused\nlaser beam and hovering 1-4 nanometers above the surface without touching it.\nThe floating tip nanowriting is compared to mechanical surface scratching, and\nis found to be much more reproducible, and of higher quality. In an\nApertureless Scanning Near Field Optical Microscope geometry the tip is\nilluminated by a focused femtosecond laser, leading to two different, clearly\nidentifiable mechanisms for removing material from the surface: when heated by\nthe laser beam, the hot-tip thermally patterns the surface of low melting\ntemperature soft materials, and when focused right at the apex of the sharp\ntip, the enhanced electric field of the laser beam causes ablation in high\nmelting temperature metal films.",
        "positive": "Pressure-induced structural phase transitions of zirconium: An ab initio\n  study based on statistical ensemble theory: The structural phase behaviors of pure zirconium metal under compressions up\nto $160$ GPa at room temperature are investigated from the perspective of\nensemble theory where the partition function is solved by our recently proposed\nmethod with \\emph{ab initio} precision. The derived Gibbs free energy is\nemployed as the very criterion to determine phase transitions and the\ncalculated transition pressures of the\n$\\alpha\\rightarrow\\omega\\rightarrow\\beta$ are $6.93$ and $24.83$ GPa\nrespectively, the former one of which is so far the only theoretical result\nagreeing with multiple experimental measurements to our best knowledge. The\ndifferences between the obtained parameter-free equation of state and those\nfrom latest experiments are less than $1.5\\%$ in the whole studied pressure\nrange, and particularly, within $0.7\\%$ when the applied pressure exceeds over\n$40$ GPa, the coincidence of which makes us support the argument that the\npreviously observed anharmonicity-driven isostructural phase transition does\nnot exist in the $\\beta$-phase even though the thermal effects at room\ntemperature are confirmed to be nontrivial to the phase stability by our\nquantitative comparisons with the results at $0$K."
    },
    {
        "anchor": "Characterization of Al and Mg Alloys from Their X-Ray Emission Bands: The valence states of Mg-Al alloys are compared to those of reference\nmaterials (pure Mg and Al metals, and intermetallics). Two methods based on\nX-ray emission spectroscopy are proposed to determine the phases and their\nproportion: first, by analyzing the Al valence spectra of the Mg-rich alloys\nand the Mg valence spectra of the Al-rich alloys; second, by fitting with a\nlinear combination of the reference spectra the Al spectra of the Al-rich\nalloys and the Mg spectra of the Mg-rich alloys. This enables us to determine\nthat Al and Al3Mg2 are present in the 0-43.9 wt% Al composition range and Mg\nand Al12Mg17 are present in the 62.5-100 wt% Al composition range. In the\n43.9-62.5% Al range, the alloy is single phase and an underestimation of the Al\ncontent of the alloy can be estimated from the comparison of the bandwidth of\nthe alloy spectrum to the bandwidths of the reference spectra.",
        "positive": "Dielectric Properties of Polysulfone Carbon Nanotube Composite Membranes: Polymeric membranes, including Polysulfone (PSf) membranes, are routinely\nused for water treatment. To enhance water permeation of above membranes, it is\ncommon to synthesize polymeric membranes with carbon nanotubes (CNTs) embedded\nin them. It is seen that water permeability of membranes having vertically\naligned CNTs is higher, as compared to those where CNTs are not aligned. It is\nof interest to examine if the dielectric constant of a CNT based nanocomposite\nmembrane is sensitive to alignment of CNTs or not. This paper reports\ndielectric properties of PSf-MWCNT membranes, both, for aligned and unaligned\nMWCNTs. Multi Walled Carbon Nanotubes (MWCNTs) based polysulfone membranes were\nsynthesized using standard methods. MWCNTs in above membranes were aligned by\ncasting the membrane in presence of magnetic field. The present paper, for the\nfirst time, shows that the above result is valid for membranes also."
    },
    {
        "anchor": "Non-monotonicity of the frictional bimaterial effect: Sliding along frictional interfaces separating dissimilar elastic materials\nis qualitatively different from sliding along interfaces separating identical\nmaterials due to the existence of an elastodynamic coupling between interfacial\nslip and normal stress perturbations in the former case. This bimaterial\ncoupling has important implications for the dynamics of frictional interfaces,\nincluding their stability and rupture propagation along them. We show that\nwhile this bimaterial coupling is a monotonically increasing function of the\nbimaterial contrast, when it is coupled to interfacial shear stress\nperturbations through a friction law, various physical quantities exhibit a\nnon-monotonic dependence on the bimaterial contrast. In particular, we show\nthat for a regularized Coulomb friction, the maximal growth rate of unstable\ninterfacial perturbations of homogeneous sliding is a non-monotonic function of\nthe bimaterial contrast, and provide analytic insight into the origin of this\nnon-monotonicity. We further show that for velocity-strengthening\nrate-and-state friction, the maximal growth rate of unstable interfacial\nperturbations of homogeneous sliding is also a non-monotonic function of the\nbimaterial contrast. Results from simulations of dynamic rupture along a\nbimaterial interface with slip-weakening friction provide evidence that the\ntheoretically predicted non-monotonicity persists in non-steady, transient\nfrictional dynamics.",
        "positive": "Operando real-space imaging of a structural phase transformation in a\n  high-voltage electrode: Discontinuous solid-solid phase transformations play a pivotal role in\ndetermining properties of rechargeable battery electrodes. By leveraging\noperando Bragg Coherent Diffractive Imaging (BCDI), we investigate the\ndiscontinuous phase transformation in LixNi0.5Mn1.5O4 within a fully\noperational battery. Throughout Li-intercalation, we directly observe the\nnucleation and growth of the Li-rich phase within the initially charged Li-poor\nphase in a 500 nm particle. Supported by the microelasticity model, the\noperando imaging unveils an evolution from a curved coherent to planar\nsemi-coherent interface driven by dislocation dynamics. We hypothesize these\ndislocations exhibit a glissile motion that facilitates interface migration\nwithout diffusion of host ions, leaving the particle defect-free\npost-transformation. Our data indicates negligible kinetic limitations\nimpacting the transformation kinetics, even at discharge rates as fast as C/2.\nThis study underscores BCDI's capability to provide operando insights into\nnanoscale phase transformations, offering valuable guidance for electrochemical\nmaterials design and optimization."
    },
    {
        "anchor": "Nonlinear hysteretic behavior of a confined sliding layer: A nonlinear model representing the tribological problem of a thin solid\nlubricant layer between two sliding periodic surfaces is used to analyze the\nphenomenon of hysteresis at pinning/depinning around a moving state rather than\naround a statically pinned state. The cycling of an external driving force\nF_ext is used as a simple means to destroy and then to recover the dynamically\npinned state previously discovered for the lubricant center-of-mass velocity.\nDe-pinning to a quasi-freely sliding state occurs either directly, with a\nsingle jump, or through a sequence of discontinuous transitions. The\nintermediate sliding steps are reminiscent of phase-locked states and\nstick-slip motion in static friction, and can be interpreted in terms of the\nappearance of travelling density defects in an otherwise regular arrangement of\nkinks. Re-pinning occurs more smoothly, through the successive disappearance of\ndifferent travelling defects. The resulting bistability and multistability\nregions may also be explored by varying mechanical parameters other than F_ext,\ne.g. the sliding velocity or the corrugation amplitude of the sliders.",
        "positive": "A wet etching method for few-layer black phosphorus with an atomic\n  accuracy and compatibility with major lithography techniques: This paper reports a few-layer black phosphorus thickness pattern fabricated\nby a top-down nanofabrication approach. This was achieved by a new wet etching\nprocess that can etch selected regions of few-layer black phosphorus with an\natomic layer accuracy. This method is deep-UV and e-beam lithography process\ncompatible,and is free of oxygen and other common doping sources. It provides a\nfeasible patterning approach for largescale manufacturing of few-layer BP\nmaterials and devices."
    },
    {
        "anchor": "Direct Measurement of the Electronic Structure and band gap nature of\n  atomic-layer-thick 2H-MoTe2: The millimeter sized monolayer and bilayer 2H-MoTe2 single crystal samples\nare prepared by a new mechanical exfoliation method. Based on such high-quality\nsamples, we report the first direct electronic structure study on them, using\nstandard high resolution angle-resolved photoemission spectroscopy (ARPES). A\ndirect band gap of 0.924eV is found at K in the rubidium-doped monolayer MoTe2.\nSimilar valence band alignment is also observed in bilayer MoTe2,supporting an\nassumption of a analogous direct gap semiconductor on it. Our measurements\nindicate a rather large band splitting of 212meV at the valence band maximum\n(VBM) in monolayer MoTe2, and the splitting is systematically enlarged with\nlayer stacking, from monolayer to bilayer and to bulk. Meanwhile, our PBE band\ncalculation on these materials show excellent agreement with ARPES results.\nSome fundamental electronic parameters are derived from the experimental and\ncalculated electronic structures. Our findings lay a foundation for further\napplication-related study on monolayer and bilayer MoTe2.",
        "positive": "The intercalation phase diagram of Mg in V$_2$O$_5$ from first\n  principles: We have investigated Mg intercalation into orthorhombic V$_2$O$_5$, one of\nonly three cathodes known to reversibly intercalate Mg ions. By calculating the\nground state Mg$_x$V$_2$O$_5$ configurations and by developing a cluster\nexpansion for the configurational disorder in $\\delta$-V$_2$O$_5$, a full\ntemperature-composition phase diagram is derived. Our calculations indicate an\nequilibrium phase separating behavior between fully demagnesiated\n$\\alpha$-V$_2$O$_5$ and fully magnesiated $\\delta$-V$_2$O$_5$, but also\nmotivate the existence of potentially metastable solid solution transformation\npaths in both phases. We find significantly better mobility for Mg in the\n$\\delta$ polymorph suggesting that better performance can be achieved by\ncycling Mg in the $\\delta$ phase."
    },
    {
        "anchor": "Energy gaps, magnetism, and electric field effects in bilayer graphene\n  nanoribbons: Using a first principles density functional electronic structure method, we\nstudy the energy gaps and magnetism in bilayer graphene nanoribbons as a\nfunction of the ribbon width and the strength of an external electric field\nbetween the layers. We assume AB (Bernal) stacking and consider both armchair\nand zigzag edges and two edge alignments distinguished by a 60$^o$ rotation of\none layer with respect to the other. Armchair ribbons exhibit three classes of\nbilayer gaps which decrease with increasing ribbon width. An external electric\nfield between the layers increases the gap in narrow ribbons and decreases the\ngap for wide ribbons, a property which can be understood semi-analytically\nusing a $\\pi$-band tight-binding model and perturbation theory. The magnetic\nproperties of zigzag edge ribbons are different for the two different edge\nalignments, and not robust for all exchange-correlation approximations\nconsidered. Bilayer ribbon gaps are sensitive to the presence or absence of\nmagnetism.",
        "positive": "Multiple polarization orders in individual twinned colloidal\n  nanocrystals of centrosymmetric HfO2: Spontaneous polarization is essential for ferroelectric functionality in\nnon-centrosymmetric crystals. High-integration-density ferroelectric devices\nrequire the stabilization of ferroelectric polarization in small volumes. Here,\natomic-resolution transmission electron microscopy imaging reveals that\ntwinning-induced symmetry breaking in colloidal nanocrystals of centrosymmetric\nHfO2 leads to the formation of multiple polarization orders, which are\nassociated with sub-nanometer ferroelectric and antiferroelectric phases. The\nminimum size limit of the ferroelectric phase is found to be ~4 nm3. Density\nfunctional theory calculations indicate that transformations between the\nferroelectric and antiferroelectric phases can be modulated by lattice strain\nand are energetically possible in either direction. The results of this work\nprovide a route towards applications of HfO2 nanocrystals in information\nstorage at densities that are more than an order of magnitude higher than the\nscaling limit defined by the nanocrystal size."
    },
    {
        "anchor": "Surface Energetics of Alkaline-Earth Metal Oxides: Trends in Stability\n  and Adsorption of Small Molecules: We present a systematic theoretical investigation of the surface properties,\nstability and reactivity, of rock-salt type alkaline-earth metal oxides\nincluding MgO, CaO, SrO, and BaO. The accuracy of commonly used\nexchange-correlation density functionals (LDA, PBE, RPBE, PBEsol, BEEF-vdW and\nhybrid HSE) and random-phase approximation (RPA) is evaluated and compared to\nexisting experimental values. Calculated surface energies of the four most\nstable surface facets under vacuum conditions: the (100) surface, the metal and\noxygen terminated octopolar (111), and the (110) surfaces exhibit a monotonic\nincrease in stability from MgO to BaO. On the MgO(100) surface, adsorption of\nCO, NO, CH4 is characterized by physisorption while H2O chemisorbs, which is in\nagreement with experimental findings. We further use the on-top metal\nadsorption of CO and NO molecules to map out the surface energetics of each\nalkaline-earth metal oxide surface. The considered functionals all\nqualitatively predict similar adsorption energy trends. The ordering between\nthe adsorption energies on different surface facets can be attributed to\ndifferences in the local geometrical surface structure and the electronic\nstructure of the metal constituent of the alkaline-earth metal oxide. The\nstriking observation that CO adsorption strength is weaker than NO adsorption\non the (100) terraces as the period of the alkaline-earth metal in the oxide\nincreases, is analyzed in detail in terms of charge redistribution within the\n{\\sigma} and {\\pi} channels of adsorbates. Finally, we also present oxygen\nadsorption and oxygen vacancy formation energies in these oxide systems.",
        "positive": "Bonding Structures of ZrHx Thin Films by X-ray Spectroscopy: The variation in local atomic structure and chemical bonding of ZrHx (x=0.15,\n0.30, 1.16) magnetron sputtered thin films are investigated by Zr K-edge (1s)\nX-ray absorption near-edge structure and extended X-ray absorption fine\nstructure spectroscopies. A chemical shift of the Zr K-edge towards higher\nenergy with increasing hydrogen content is observed due to charge-transfer and\nan ionic or polar covalent bonding component between the Zr 4d and the H 1s\nstates with increasing valency for Zr. We find an increase in the Zr-Zr bond\ndistance with increasing hydrogen content from 3.160 {\\AA} in the hexagonal\nclosest-packed metal (alpha-phase) to 3.395 {\\AA} in the understoichiometric\ndelta-ZrHx film (CaF2-type structure) with x=1.16 that largely resembles that\nof bulk delta-ZrH2. For yet lower hydrogen contents, the structures are mixed\nalpha and delta-phases, while sufficient hydrogen loading (x>1) yields a pure\n{\\delta}-phase that is understoichiometric, but thermodynamically stable. The\nchange in the hydrogen content and strain is discussed in relation to the\ncorresponding change of bond lengths, hybridizations, and trends in electrical\nresistivity."
    },
    {
        "anchor": "Rate theory of acceleration of the defect annealing driven by discrete\n  breathers: Novel mechanisms of defect annealing in solids are discussed, which are based\non the large amplitude anharmonic lattice vibrations, a.k.a. intrinsic\nlocalized modes or discrete breathers (DBs). A model for amplification of\ndefect annealing rate in Ge by low energy plasma-generated DBs is proposed, in\nwhich, based on recent atomistic modelling, it is assumed that DBs can excite\natoms around defects rather strongly, giving them energy $\\gg k_BT$ for\n$\\sim$100 oscillation periods. This is shown to result in the amplification of\nthe annealing rates proportional to the DB flux, i.e. to the flux of ions (or\nenergetic atoms) impinging at the Ge surface from inductively coupled plasma\n(ICP)",
        "positive": "Cooperation and Environment Characterize the Low-Lying Optical Spectrum\n  of Liquid Water: The optical spectrum of liquid water is analyzed by subsystem time-dependent\ndensity functional theory. We provide simple explanations for several important\n(and so far elusive) features. Due to the disordered environment surrounding\neach water molecule, the joint density of states of the liquid is much broader\nthan that of the vapor. This results in a red shifted Urbach tail. Confinement\neffects provided by the first solvation shell are responsible for the blue\nshift of the first absorption peak compared to the vapor. In addition, we also\ncharacterize many-body excitonic effects. These dramatically affect the\nspectral weights at low frequencies, contributing to the refractive index by a\nsmall but significant amount."
    },
    {
        "anchor": "Coherence Time Extension by Large Scale Optical Spin Polarization in a\n  Rare-Earth Doped Crystal: Optically addressable spins are actively investigated in quantum\ncommunication, processing and sensing. Optical and spin coherence lifetimes,\nwhich determine quantum operation fidelity and storage time, are often limited\nby spin-spin interactions, which can be decreased by polarizing spins in their\nlower energy state using large magnetic fields and/or mK range temperatures.\nHere, we show that optical pumping of a small fraction of ions with a fixed\nfrequency laser, coupled with spin-spin interactions and spin diffusion, leads\nto substantial spin polarization in a paramagnetic rare earth doped crystal,\n$^{171}$Yb$^{3+}$:YSO. Indeed, up to more than 90 % spin polarizations have\nbeen achieved at 2 K and zero magnetic field. Using this spin polarization\nmechanism, we furthermore demonstrate an increase in optical coherence lifetime\nfrom 0.3 ms to 0.8 ms, due to a strong decrease in spin-spin interactions. This\neffect opens the way to new schemes for obtaining long optical and spin\ncoherence lifetimes in various solid-state systems such as ensembles of rare\nearth ions or color centers in diamond, which is of interest for a broad range\nof quantum technologies.",
        "positive": "Revisiting Maya Blue and Designing Hybrid Pigments by Archaeomimetism: Maya Blue is actually one of the best known examples of an organic-inorganic\nhybrid material. Yet despite 50 years of sustained interest, its microscopic\nstructure and its relation to durability remain open questions. We address the\nissue by archaeomimetism: engineering an archaeoinspired pigment,\nsatisfactorily reproducing the colour and chemical stability of Maya Blue. By\ncomparing and contrasting ancient pigment and the new analogue, we deduce a new\nexplanation for this durability."
    },
    {
        "anchor": "Electrically controlled superconductor-insulator transition and giant\n  anomalous Hall effect in kagome metal CsV3Sb5 nanoflakes: The electronic correlations (e.g. unconventional superconductivity (SC),\nchiral charge order and nematic order) and giant anomalous Hall effect (AHE) in\ntopological kagome metals AV3Sb5 (A= K, Rb, and Cs) have attracted great\ninterest. Electrical control of those correlated electronic states and AHE\nallows us to resolve their own nature and origin and to discover new quantum\nphenomena. Here, we show that a protonic gate can largely modulate the\neffective disorders and carrier density in CsV3Sb5 nanoflakes, leading to\nsignificant modifications of SC, unusual charge density wave (CDW) and giant\nAHE. Notably, we observed a direct superconductor-insulator transition (SIT)\ndriven by superconducting phase fluctuation due to the doping-enhanced\ndisorders, in addition to a large suppression of CDW. Meanwhile, the carrier\ndensity modulation shifts the Fermi level across the CDW gap and gives rise to\na nontrivial evolution of AHE, in line with the asymmetric density of states of\nCDW sub-bands near the saddle point. With the first-principles calculations, we\nsuggest the extrinsic skew scattering of holes in the nearly flat bands with\nfinite Berry curvature by multiple impurities accounts for the giant AHE. Our\nwork uncovers a disorder-driven bosonic SIT, outlines a global picture of the\ngiant AHE and reveals its correlation with the unconventional CDW in the AV3Sb5\nfamily.",
        "positive": "Physical Origin of the Mechanochemical Coupling at Interfaces: We used density functional theory (DFT) calculations to investigate the\nphysical origin of the mechano-chemical response of materials interfaces. Our\nresults show that the mechano-chemical response can be decomposed into the\ncontribution from the interface itself (deformation of interfacial bonds) and a\ncontribution from the underlying solid. The relative contributions depend on\nthe stiffness of these regions and the contact geometry, which affects the\nstress distribution within the bulk region. We demonstrate that, contrary to\nwhat is commonly assumed, the contribution to the activation volume from the\nelastic deformation of the surrounding bulk is significant and, in some case,\nmay be dominant. We also show that the activation volume and the\nmechanochemical response of interfaces should be finite due to the effects on\nthe stiffness and stress distribution within the near-surface bulk region. Our\nresults indicate that the large range of activation volumes measured in the\nprevious experiments even for the same material system might originate from the\ndifferent degrees of contributions probed from the bulk vs. interface."
    },
    {
        "anchor": "Silicon-Oxide Interfaces: Structure and Electronic Properties: The paper reviews methods used to study the electronic and structural\nproperties of silicon/insulator interfaces. Methodological approaches to study\nthe interface states and charge trapping in the oxide are considered. An\noverview of archetypical structural defects of the Si/SiO2 interface is given.",
        "positive": "First Principal Investigations to Explore the Half-metallicity,\n  Structural, Mechanical, and Optoelectronic Properties of Sodium-Based\n  Fluoroperovskites NaYF3 (Y = Sc and Ti) for Applications in Spintronics and\n  Optoelectronics: A theoretical investigation was conducted on Na-based fluoro-perovskites\nNaYF3 (Y = Sc, Ti) to examine their structural, optical, electronic, and\nmechanical characteristics for the first time. These cubic compounds exhibit\nstructural stability, maintaining perovskite structures with lattice spacing\nranging from 4.15 to 4.26 {\\AA}. Computation of elastic parameters confirms\ntheir stability, ionic bonding, ductility, and anisotropy. Computed band\nprofiles reveal the half-metallic nature with indirect (M-{\\Gamma}) bandgaps\nfor the spin-down configurations. Furthermore, density-of-states analysis\nhighlights the role of Y (Sc, Ti) atoms in the metallic character and\nconduction band contribution. The lack of absorbance in the visible region\nhighlights the materials' suitability for optoelectronic devices. This\ninvestigation aims to provide comprehensive insights and encourage further\nexperimental research."
    },
    {
        "anchor": "Phase-Field Modeling of Crack Branching and Deflection in Heterogeneous\n  Media: This contribution presents a diffuse framework for modeling cracks in\nheterogeneous media. Interfaces are depicted by static phase-fields. This\nconcept allows the use of non-conforming meshes. Another phase-field is used to\ndescribe the crack evolution in a regularized manner.\n  The interface modeling implements two combined approaches. Firstly, a method\nfrom the literature is extended where the interface is incorporated by a local\nreduction of the fracture toughness. Secondly, variations of the elastic\nproperties across the interface are enabled by approximating the abrupt change\nbetween two adjacent subdomains using a hyperbolic tangent function, which\nalters the elastic material parameters accordingly.\n  The approach is validated qualitatively by means of crack patterns and\nquantitatively with respect to critical energy release rates with fundamental\nanalytical results from Linear Elastic Fracture Mechanics, where a crack\nimpinges an arbitrarily oriented interface and either branches, gets deflected\nor experiences no interfacial influence. The model is particularly relevant for\nphase-field analyses in heterogeneous, possibly complex-shaped solids, where\ncohesive failure in the constituent materials as well as adhesive failure at\ninterfaces and its quantification play a role.",
        "positive": "Finite viscoelasticity of filled rubbers: the effects of pre-loading and\n  thermal recovery: Constitutive equations are derived for the viscoelastic behavior of filled\nelastomers at isothermal loading with finite strains. A particle-reinforced\nrubber is thought of as a composite where regions with low concentrations of\njunctions between chains are randomly distributed in the bulk material. The\nonset of these inclusions is associated with the inhomogeneity in spatial\ndistribution of a cross-linker during the mixing process. With reference to the\ntheory of transient networks, the time-dependent response of an elastomer is\nmodelled as thermally activated processes of breakage and reformation of chains\nin domains with low concentrations of junctions, whereas junctions in the bulk\nmedium are treated as permanent. Stress-strain relations are developed by using\nthe laws of thermodynamics. Adjustable parameters in the constitutive equations\nare found by fitting experimental data in tensile relaxation tests for several\ngrades of unfilled and carbon black filled natural rubber. It is demonstrated\nthat (i) the average relaxation time noticeably grows with the elongation\nratio, which is explained by mechanically-induced crystallization of strands,\nand (ii) the relaxation spectrum of a filled elastomer is not affected by\nmechanical pre-loading and thermal recovery at elevated temperatures."
    },
    {
        "anchor": "Extended Huckel theory for bandstructure, chemistry and transport. I.\n  Carbon Nanotubes: We describe a semi-empirical atomic basis Extended H\\\"uckel Theoretical (EHT)\ntechnique that can be used to calculate bulk bandstructure, surface density of\nstates, electronic transmission and interfacial chemistry of various materials\nwithin the same computational platform. We apply this method to study multiple\ntechnologically important systems, starting with carbon-nanotubes (CNT) and\ntheir interfaces in this paper, and silicon-based heterostructures in our\nfollow-up paper. We find that when it comes to quantum transport through\ninteresting, complex heterostructures, the Huckel bandstructure offers a fair\nand practical compromise between orthogonal tight-binding theories (OTB) with\nlimited transferability between environments under large distortion, and\ndensity functional theories (DFT) that are computationally quite expensive for\nthe same purpose.",
        "positive": "Ultrafast graphene photodetector: The electronic properties of graphene are unique and are attracting increased\nattention to this novel 2-dimensional system. Its photonic properties are not\nless impressive. For example, this single atomic layer absorbs through direct\ninterband transitions a considerable fraction of the light (~2.3%) over a very\na broad wavelength range. However, while applications in electronics are\nvigorously being pursued, photonic applications have not attracted as much\nattention. Here, we report on ultrafast photocurrent response measurements in\ngraphene (single and few-layers) field-effect-transistors (FETs) up to 40 GHz\nlight intensity modulation frequencies, using a 1.55 micron excitation laser.\nNo photoresponse degradation is observable up to the highest measured\nfrequency, demonstrating the feasibility and unique benefits of using graphene\nin photonics. Further analysis suggests that the intrinsic bandwidth of such\ngraphene FET based photodetectors may exceed 500 GHz. Most notably, the\ngeneration and transport of the photo-carriers in such graphene photodetectors\nare fundamentally different from those in currently known semiconductor\nphotodetectors, leading to a remarkably high bandwidth, zero source-drain bias\n(hence zero dark current) operation, and good internal quantum efficiency."
    },
    {
        "anchor": "Incorporation and control of defects with quantum functionality during\n  sublimation growth of cubic silicon carbide: Superconductor based quantum computing has the major drawback of working\ntemperatures which require liquid helium for cooling. A promising approach to\novercome this obstacle for quantum technologies is based on deep level defects\nin semiconductors, with the nitrogen vacancy (NV) center in diamond being the\nmost prominent example. Unfortunately, diamond in sufficient quality is scarce,\nwhich motivated efforts to find similar defects in silicon carbide (SiC). So\nfar, many reports focus on investigations of point defects in irradiated 3C-SiC\nand as grown material. However, the investigated defects are more or less a\nproduct of coincidence for both. While in irradiated material the intentional\ngeneration of specific defects is rather challenging, in as purchased material\nthe defects are actually more an unintentional by product of growth and process\nconditions. This work proposes a new route: the incorporation and control of\ndeep level defects in 3C-SiC by epitaxial sublimation growth. The observed\ndefects in the near infrared show bright luminescence in the 175 K/200 K regime\nand remain excitable up to 300 K. This could enable working temperatures above\nthe cryogenic limit. The joint origin of all detected defects is assigned to\nthe carbon vacancy.",
        "positive": "Magnetization flip in Fe-Cr-Ga system: A systematic investigation about the structure and magnetism of Fe75-xCr25Gax\n(11<x<33) and Fe50Cr50-yGay (0<y<33) series has been carried out in this work.\nIt shows that the parent Fe50Cr25Ga25 phase has higher tolerance for Ga\nreplacing Cr than replacing Fe atoms. An abrupt flip of Curie temperature and\nmagnetization in the Fe50Cr50-yGay (0<y<33) series was observed at the\ncomposition of Fe50Cr25Ga25. We proposed an explanation concerning anti-sites\noccupation and magnetic structure transition in this series. The induced\nstructure is proved energetically favorable from first-principles calculations.\nThis work can help us to understand the dependences between the crystal\nstructure and magnetism in Fe-based Heusler compounds, and provides a method to\ndeduce the atomic configurations based on the evolution of magnetism."
    },
    {
        "anchor": "InP nanocrystals on silicon for optoelectronic applications: One of the solutions enabling performance progress, which can overcome the\ndownsizing limit in silicon technology, is the integration of different\nfunctional optoelectronic devices within a single chip. Silicon with its\nindirect band gap has poor optical properties, which is its main drawback.\nTherefore, a different material has to be used for the on-chip optical\ninterconnections, e.g. a direct band gap III-V compound semiconductor material.\nIn the paper we present the synthesis of single crystalline InP nanodots (NDs)\non silicon using combined ion implantation and millisecond flash lamp annealing\ntechniques. The optical and microstructural investigations reveal the growth of\nhigh-quality (100)-oriented InP nanocrystals. The current-voltage measurements\nconfirm the formation of an n-p heterojunction between the InP NDs and silicon.\nThe main advantage of our method is its integration with large-scale silicon\ntechnology, which allows applying it for Si-based optoelectronic devices.",
        "positive": "Metallic and insulating interfaces of amorphous SrTiO3-based oxide\n  heterostructures: The conductance confined at the interface of complex oxide heterostructures\nprovides new opportunities to explore nanoelectronic as well as nanoionic\ndevices. Herein we show that metallic interfaces can be realized in\nSrTiO3-based heterostructures with various insulating overlayers of amorphous\nLaAlO3, SrTiO3 and yttria-stabilized zirconia films. On the other hand, samples\nof amorphous La7/8Sr1/8MnO3 films on SrTiO3 substrates remain insulating. The\ninterfacial conductivity results from the formation of oxygen vacancies near\nthe interface, suggesting that the redox reactions on the surface of SrTiO3\nsubstrates play an important role."
    },
    {
        "anchor": "Any order imaginary time propagation method for solving the Schrodinger\n  equation: The eigenvalue-function pair of the 3D Schr\\\"odinger equation can be\nefficiently computed by use of high order, imaginary time propagators. Due to\nthe diffusion character of the kinetic energy operator in imaginary time,\nalgorithms developed so far are at most fourth-order. In this work, we show\nthat for a grid based algorithm, imaginary time propagation of any even order\ncan be devised on the basis of multi-product splitting. The effectiveness of\nthese algorithms, up to the 12$^{\\rm th}$ order, is demonstrated by computing\nall 120 eigenstates of a model C$_{60}$ molecule to very high precisions. The\nalgorithms are particularly useful when implemented on parallel computer\narchitectures.",
        "positive": "Charge density wave and superconducting dome in TiSe2 from\n  electron-phonon interaction: At low temperature TiSe2 undergoes a charge density wave instability.\nSuperconductivity is stabilized either by pressure or by Cu intercalation. We\nshow that the pressure phase diagram of TiSe2 is well described by\nfirst-principles calculations. At pressures smaller than 4 GPa charge density\nwave ordering occurs, in agreement with experiments. At larger pressures the\ndisappearing of the charge density wave is due to a stiffening of the\nshort-range force-constants and not to the variation of nesting with pressure.\nFinally we show that the behavior of Tc as a function of pressure is entirely\ndetermined by the electron-phonon interaction without need of invoking\nexcitonic mechanisms. Our work demonstrates that phase-diagrams with competing\norders and a superconducting dome are also obtained in the framework of the\nelectron-phonon interaction."
    },
    {
        "anchor": "Origin of relaxor behavior in barium-titanate based lead-free\n  perovskites: It is well known that disordered relaxor ferroelectrics exhibit local polar\ncorrelations. The origin of localized fields that disrupt long range polar\norder for different substitution types, however, is unclear. Currently, it is\nknown that substituents of the same valence as Ti4+ at the B-site of barium\ntitanate lattice produce random disruption of Ti-O-Ti chains that induces\nrelaxor behavior. On the other hand, investigating lattice disruption and\nrelaxor behavior resulting from substituents of different valence at the B-site\nis more complex due to the simultaneous occurrence of charge imbalances and\ndisplacements of the substituent cation. The existence of an effective charge\nmediated mechanism for relaxor behavior appearing at low (< 10%) substituent\ncontents in heterovalent modified barium titanate ceramics is presented in this\nwork. These results will add credits to the current understanding of relaxor\nbehavior in chemically modified ferroelectric materials and also acknowledge\nthe critical role of defects (such as cation vacancies) in lattice disruption,\npaving the way for chemistry-based materials design in the field of dielectric\nand energy storage applications.",
        "positive": "Eight-potential-well order-disorder ferroelectric model and effects of\n  random fields: An eight-potential-well order-disorder ferroelectric model was presented and\nthe phase transition was studied under the mean-field approximation. It was\nshown that the two-body interactions are able to account for the first-order\nand the second order phase transitions. With increasing the random fields in\nthe system, a first-order phase transition is transformed into a second-order\nphase transition, and furthermore, a second-order phase transition is\ninhibited.\n  However, proper random fields can promote the spontaneous appearance of a\nfirst-order phase transition by increasing the overcooled temperature. The\nconnections of the model with relaxors were discussed."
    },
    {
        "anchor": "Infrared reflectivity of the phonon spectra in multiferroic TbMnO3: We measured the temperature dependent infrared reflectivity spectra of TbMnO3\nwith the electric field of light polarized along each of the three\ncrystallographic axes. We analyzed the effect, on the phonon spectra, of the\ndifferent phase transitions occurring in this material. We show that the\nantiferromagnetic transition at TN renormalizes the phonon parameters along the\nthree directions. Our data indicate that the electromagnon, observed along the\na direction, has an important contribution to the building of the dielectric\nconstant. Only one phonon, observed along the c-axis, has anomalies at the\nferroelectric transition. This phonon is built mostly from Mn vibrations,\nsuggesting that Mn displacements are closely related to the formation of the\nferroelectric order.",
        "positive": "Computing the Absolute Gibbs Free Energy in Atomistic Simulations:\n  Applications to Defects in Solids: The Gibbs free energy is the fundamental thermodynamic potential underlying\nthe relative stability of different states of matter under constant-pressure\nconditions. However, computing this quantity from atomic-scale simulations is\nfar from trivial. As a consequence, all too often the potential energy of the\nsystem is used as a proxy, overlooking entropic and anharmonic effects. Here we\ndiscuss a combination of different thermodynamic integration routes to obtain\nthe absolute Gibbs free energy of a solid system starting from a harmonic\nreference state. This approach enables the direct comparison between the free\nenergy of different structures, circumventing the need to sample the transition\npaths between them. We showcase this thermodynamic integration scheme by\ncomputing the Gibbs free energy associated with a vacancy in BCC iron, and the\nintrinsic stacking fault free energy of nickel. These examples highlight the\npitfalls of estimating the free energy of crystallographic defects only using\nthe minimum potential energy, which overestimates the vacancy free energy by\n60% and the stacking-fault energy by almost 300% at temperatures close to the\nmelting point."
    },
    {
        "anchor": "Electronic and magnetic characterization of epitaxial CrBr$_3$\n  monolayers: The ability to imprint a given material property to another through proximity\neffect in layered two-dimensional materials has opened the way to the creation\nof designer materials. Here, we use molecular-beam epitaxy (MBE) for a direct\nsynthesis of a superconductor-magnet hybrid heterostructure by combining\nsuperconducting niobium diselenide (NbSe$_2$) with the monolayer ferromagnetic\nchromium tribromide (CrBr$_3$). Using different characterization techniques and\ndensity-functional theory (DFT) calculations, we have confirmed that the\nCrBr$_3$ monolayer retains its ferromagnetic ordering with a magnetocrystalline\nanisotropy favoring an out-of-plane spin orientation. Low-temperature scanning\ntunneling microscopy (STM) measurements show a slight reduction of the\nsuperconducting gap of NbSe$_2$ and the formation of a vortex lattice on the\nCrBr$_3$ layer in experiments under an external magnetic field. Our results\ncontribute to the broader framework of exploiting proximity effects to realize\nnovel phenomena in 2D heterostructures.",
        "positive": "\\textit{Ab Initio} Study of the Magnetic Behavior of Metal Hydrides: A\n  Comparison with the Slater-Pauling Curve: We investigated the magnetic behavior of metal hydrides FeH$_{x}$, CoH$_{x}$\nand NiH$_{x}$ for several concentrations of hydrogen ($x$) by using Density\nFunctional Theory calculations. Several structural phases of the metallic host:\nbcc ($\\alpha$), fcc ($\\gamma$), hcp ($\\varepsilon$), dhcp ($\\varepsilon'$),\ntetragonal structure for FeH$_{x}$ and $\\varepsilon$-$\\gamma$ phases for\nCoH$_{x}$, were studied. We found that for CoH$_{x}$ and NiH$_{x}$ the magnetic\nmoment ($m$) decreases regardless the concentration $x$. However, for FeH$_{x}$\nsystems, $m$ increases or decreases depending on the variation in $x$. In order\nto find a general trend for these changes of $m$ in magnetic metal hydrides, we\ncompare our results with the Slater-Pauling curve for ferromagnetic metallic\nbinary alloys. It is found that the $m$ of metal hydrides made of Fe, Co and Ni\nfits the shape of the Slater-Pauling curve as a function of $x$. Our results\nindicate that there are two main effects that determine the $m$ value due to\nhydrogenation: an increase of volume causes $m$ to increase, and the addition\nof an extra electron to the metal always causes it to decrease. We discuss\nthese behaviors in detail."
    },
    {
        "anchor": "Non-thermal transport of energy driven by photoexcited carriers in\n  switchable solid states of GeTe: Phase change alloys have seen widespread use from rewritable optical discs to\nthe present day interest in their use in emerging neuromorphic computing\narchitectures. In spite of this enormous commercial interest, the physics of\ncarriers in these materials is still not fully understood. Here, we describe\nthe time and space dependence of the coupling between photoexcited carriers and\nthe lattice in both the amorphous and crystalline states of one phase change\nmaterial, GeTe. We study this using a time-resolved optical technique called\npicosecond acoustic method to investigate the \\textit{in situ} thermally\nassisted amorphous to crystalline phase transformation in GeTe. Our work\nreveals a clear evolution of the electron-phonon coupling during the phase\ntransformation as the spectra of photoexcited acoustic phonons in the amorphous\n($a$-GeTe) and crystalline ($\\alpha$-GeTe) phases are different. In particular\nand surprisingly, our analysis of the photoinduced acoustic pulse duration in\ncrystalline GeTe suggests that a part of the energy deposited during the\nphotoexcitation process takes place over a distance that clearly exceeds that\ndefined by the pump light skin depth. In the opposite, the lattice\nphotoexcitation process remains localized within that skin depth in the\namorphous state. We then demonstrate that this is due to supersonic diffusion\nof photoexcited electron-hole plasma in the crystalline state. Consequently\nthese findings prove the existence of a non-thermal transport of energy which\nis much faster than lattice heat diffusion.",
        "positive": "Monolithic Selenium/Silicon Tandem Solar Cells: Selenium is experiencing renewed interest as a promising candidate for the\nwide bandgap photoabsorber in tandem solar cells. However, despite the\npotential of selenium-based tandems to surpass the theoretical efficiency limit\nof single junction devices, such a device has never been demonstrated. In this\nstudy, we present the first monolithically integrated selenium/silicon tandem\nsolar cell. Guided by device simulations, we investigate various\ncarrier-selective contact materials and achieve encouraging results, including\nan open-circuit voltage of V$_\\text{oc}$=1.68 V from suns-V$_\\text{oc}$\nmeasurements. The high open-circuit voltage positions selenium/silicon tandem\nsolar cells as serious contenders to the industrially dominant single junction\ntechnologies. Furthermore, we quantify a pseudo fill factor of more than 80%\nusing injection-level-dependent open-circuit voltage measurements, indicating\nthat a significant fraction of the photovoltaic losses can be attributed to\nparasitic series resistance. This work provides valuable insights into the key\nchallenges that need to be addressed for realizing higher efficiency\nselenium/silicon tandem solar cells."
    },
    {
        "anchor": "Luminescence of photochromic centers in calcium fluoride crystals doped\n  with Lu$^{3+}$ ions: We report data on the luminescence spectra associated with photochromic\ncenters in X-ray irradiated calcium fluoride crystals doped with Lu ions.\nIrradiation in low energy photochromic centers absorption band excites\nemission, which can be identify with transitions into photochromic centers. Ab\ninitio calculation of absorption spectrum of photochromic center agrees rather\nwell with experimental data.",
        "positive": "Phonon Transmission Rate, Fluctuations, and Localization in Random\n  Semiconductor Superlattices: Green's Function Approach: We analytically study phonon transmission and localization in random\nsuperlattices by using a Green's function approach. We derive expressions for\nthe average transmission rate and localization length, or Lyapunov exponent, in\nterms of the superlattice structure factor. This is done by considering the\nbackscattering of phonons, due to the complex mass density fluctuations, which\nincorporates all of the forward scattering processes. These analytical results\nare applied to two types of random superlattices and compared with numerical\nsimulations based on the transfer matrix method. Our analytical results show\nexcellent agreement with the numerical data. A universal relation for the\ntransmission fluctuations versus the average transmission is derived\nexplicitly, and independently confirmed by numerical simulations. The transient\nof the distribution of transmission to the log-normal distribution for the\nlocalized phonons is also studied."
    },
    {
        "anchor": "Enhancement of quantum capacitance in graphene electrodes by chemical\n  modifications using aliphatic/aromatic molecules and their radicals: We have carried out the systematic study of quantum capacitance (C$_Q$) in\nfunctionalized graphene. The functionlization of graphene has been done by\ndoping with different aliphatic and aromatic molecules and their radicals.\nUsing density functional theory calculations, we first analyze the electronic\nband structure of the functionalized graphene and subsequently obtained the\nquantum capacitance in each system. We observed that the quantum capacitance\ncan be enhanced by doping aliphatic and aromatic molecules and their radicals\non graphene sheet, especially radical functionalized graphene shows significant\nenhancement in C$_Q$. Our theoretical investigation reveals that aromatic and\naliphatic radicals generates localized density of states near the Fermi level,\ndue to a charge localization. As a result, a very high quantum capacitance\n(above 200 $\\mu F/cm^2$) compared to pristine graphene has been estimated.\nEffects of atomic dislocation and the vacancy defect on graphene during\nfunctionalization has also been incorporated in our investigation. Obtain\nresults predict that the formation of molecular radicals while\nfunctionalization of graphene could be an efficient way to synthesize highly\nefficient graphene based supercapacitor electrode materials which in turn may\nsignificantly improve the performance of supercapacitors.",
        "positive": "Modeling and Simulation of Liquid Crystal Elastomers: We consider a continuum model describing the dynamic behavior of nematic\nliquid crystal elastomers (LCEs) and implement a numerical scheme to solve the\ngoverning equations. In the model, the Helmholtz free energy and Rayleigh\ndissipation are used, within a Lagrangian framework, to obtain the equations of\nmotion. The free energy consists of both elastic and liquid crystalline\ncontributions, each of which is a function of the material displacement and the\norientational order parameter. The model gives dynamics for the material\ndisplacement, the scalar order parameter and the nematic director, the latter\ntwo of which correspond to the orientational order parameter tensor. Our\nsimulations are carried out by solving the governing equations using an\nimplicit-explicit scheme and the Chebyshev polynomial method. The simulations\nshow that the model can successfully capture the shape changing dynamics of\nLCEs that have been observed in experiments, and also track the evolution of\nthe order parameter tensor."
    },
    {
        "anchor": "Quaternary two-dimensional (2D) transition metal dichalcogenides (TMDs)\n  with tunable bandgap: Alloying/doping in two-dimensional material has been important due to wide\nrange band gap tunability. Increasing the number of components would increase\nthe degree of freedom which can provide more flexibility in tuning the band gap\nand also reduced the growth temperature. Here, we report synthesis of\nquaternary alloys MoxW1-xS2ySe2(1-y) using chemical vapour deposition. The\ncomposition of alloys has been tuned by changing the growth temperatures. As a\nresult, we can tune the bandgap which varies from 1.73 eV to 1.84 eV. The\ndetailed theoretical calculation supports the experimental observation and\nshows a possibility of wide tunability of bandgap.",
        "positive": "Quantifying the factors limiting rate-performance in battery electrodes: A significant problem associated with batteries is the rapid reduction of\ncharge-storage capacity with increasing charge/discharge rate. For example,\nimproving this rate-performance is required for fast-charging of car batteries.\nRate-performance is related to the timescales associated with charge or ionic\nmotion in both electrode and electrolyte. However, no quantitative model exists\nwhich can be used to fit experimental data to give insights into the dominant\nrate-limiting processes in a given electrode-electrolyte system. Here we\ndevelop an equation which can be used to fit capacity versus rate data,\noutputting three parameters which fully describe rate-performance. Most\nimportant is the characteristic time associated with charge/discharge which can\nbe expressed by a simple equation with terms describing each rate-limiting\nprocess, thus linking rate-performance to measurable physical parameters. We\nhave fitted these equations to ~200 data sets from ~50 papers, finding\nexceptional agreement, and allowing parameters such as diffusion coefficients\nor electrolyte conductivities to be extracted. By estimating relevant physical\nparameters, it is possible to show which rate-limiting processes are dominant\nin a given situation, facilitating rational design and cell optimization. In\naddition, this model predicts the upper speed limit for Li/Na ion batteries, in\nagreement with the fastest electrodes in the literature."
    },
    {
        "anchor": "The solidification of a disk-shaped crystal from a weakly supercooled\n  binary melt: The physics of ice crystal growth from the liquid phase, especially in the\npresence of salt, has received much less attention than the growth of snow\ncrystals from the vapour phase. The growth of so-called frazil ice by\nsolidification of a supercooled aqueous salt solution is consistent with\ncrystal growth in the basal plane being limited by the diffusive removal of the\nlatent heat of solidification from the solid--liquid interface, while being\nlimited by attachment kinetics in the perpendicular direction. This leads to\nthe formation of approximately disk-shaped crystals with a low aspect ratio of\nthickness compared to radius, because radial growth is much faster than axial\ngrowth. We calculate numerically how fast disk-shaped crystals grow in both\npure and binary melts, accounting for the comparatively slow axial growth, the\neffect of dissolved solute in the fluid phase and the difference in thermal\nproperties between solid and fluid phases. We identify the main physical\nmechanisms that control crystal growth and show that the diffusive removal of\nboth the latent heat released and also the salt rejected at the growing\ninterface are significant. Our calculations demonstrate that certain previous\nparameterizations, based on scaling arguments, substantially underestimate\ncrystal growth rates by a factor of order 10-100 for low aspect ratio disks,\nand provide a parameterization for use in models of ice crystal growth in\nenvironmental settings.",
        "positive": "Surface magnetoinductive breathers in two-dimensional magnetic\n  metamaterials: We study discrete surface breathers in two-dimensional lattices of\ninductively-coupled split-ring resonators with capacitive nonlinearity. We\nconsider both Hamiltonian and dissipative systems and analyze the properties of\nthe modes localized in space and periodic in time (discrete breathers) located\nin the corners and at the edges of the lattice. We find that surface breathers\nin the Hamiltonian systems have lower energy than their bulk counterparts, and\nthey are generally more stable."
    },
    {
        "anchor": "Buckled honeycomb group-$V$--$S_6$ symmetric $(d-2)$ higher order\n  topological insulators: Higher Order Topological Insulators (HOTI) are $d$-spatial dimensional\nsystems featuring topologically protected gap-less states at their\n$(d-n)$-dimensional boundaries. With the help of \\textit{ab-initio}\ncalculations and tight binding models along with symmetry considerations we\nshow that monolayer buckled honeycomb structures of group-V elements (Sb,As),\nwhich have already been synthesized, belong in this category and have a charge\nfractionalization of $\\frac{e}{2}$ at the corner states as well as weak\ntopological edge states, all protected by their properties under the inversion\noperation which classify this system as a quadrupole topological insulator.",
        "positive": "Electronic and optical properties of C-N-codoped TiO2: A\n  first-principles GGA+U investigation: Electronic structures and optical properties of C-N-codoped anatase TiO2 were\ncalculated by using GGA+U method based on the density functional theory. The\ncalculated results showed that the N-doped, C-doped, and C-N-codoped TiO2\nproduced 2p states in band gap, and the band gaps of the three doped systems\ndecreased compared with the pure TiO2. According to the optical results, the\nband edges of the three doped systems shifted to the long wavelength region,\nand the visible optical absorption from 450 to 800 nm was observed. Moreover,\nthe visible light response of C-N-codoped TiO2 was better than the C or N\nsingle doped TiO2, indicating that there was a synergistic effect for the\nC-N-codoped TiO2, which offseted the deficiencies of C or N-doped TiO2."
    },
    {
        "anchor": "Coherent Sub-Nanosecond Switching of Perpendicular Magnetization by the\n  Field-like Spin-Orbit Torque without an External Magnetic Field: We theoretically study the influence of a predominant field-like spin-orbit\ntorque on the magnetization switching of small devices with a uniform\nmagnetization. We show that for a certain range of ratios (0.23-0.55) of the\nSlonczewski to the field-like torques, it is possible to deterministically\nswitch the magnetization without requiring any external assist field. A precise\ncontrol of the pulse length is not necessary, but the pulse edge sharpness is\ncritical. The proposed switching scheme is numerically verified to be effective\nin devices by micromagnetic simulations. Switching without any external assist\nfield is of great interest for the application of spin-orbit torques to\nmagnetic memories.",
        "positive": "Morphologies, metastability and coarsening of quantum nanoislands on the\n  surfaces of the annealed Ag(110) and Pb(111) thin films: Morphological evolution of heteroepitaxial nanoislands toward equilibrium\n(coarsening) is computed using the detailed continuum model that incorporates\nthe quantum size effect. Results reveal the metastability of the \"magic\"\nheights, show the morphological transitions and the surface diffusion routes by\nwhich a quantum island reaches its stable height, and provide the coarsening\nlaws for the island density and area, thus clarifying the kinetic morphology\npathways in the growth of an ultrathin metal films."
    },
    {
        "anchor": "Magnetic properties of 3d, 4d, and 5d transition-metal atomic monolayers\n  in Fe/TM/Fe sandwiches: Systematic first-principles study: Previous studies have accurately determined the effect of transition metal\npoint defects on the properties of bcc iron. The magnetic properties of\ntransition metal monolayers on the iron surfaces have been studied equally\nintensively. In this work, we investigated the magnetic properties of the 3d,\n4d, and 5d transition-metal (TM) atomic monolayers in Fe/TM/Fe sandwiches using\nthe full-potential local-orbital (FPLO) scheme of density functional theory. We\nprepared models of Fe/TM/Fe structures using the supercell method. We selected\nthe total thickness of our system so that the Fe atomic layers furthest from\nthe TM layer exhibit bulk iron-bcc properties. Along the direction\nperpendicular to the TM layer, we observe oscillations of spin and charge\ndensity. For Pt and W we obtained the largest values of perpendicular\nmagnetocrystalline anisotropy and for Lu and Ir the largest values of in-plane\nmagnetocrystalline anisotropy. All TM layers, except Co and Ni, reduce the\ntotal spin magnetic moment in the generated models, which is in good agreement\nwith the Slater-Pauling curve. Density of states calculations showed that for\nAg, Pd, Ir, and Au monolayers, a distinct van Hove singularity associated with\nTM/Fe interface can be observed at the Fermi level.",
        "positive": "Real-Space Imaging of the Ordered Small Molecule Orientations in Porous\n  Frameworks by Electron Microscopy: The real-space imaging of small molecules is always challenging under the\nelectron microscopes, but highly demanded for investigating various nanoscale\ninteractions, such as hydrogen bond and van der Waals (vdW) force. Especially,\nidentifying the host-guest interactions in porous materials directly at the\nmolecular level will bring a deeper insight into the behaviors of guest\nmolecules during the sorption, catalysis, gas separation and energy storage. In\nthis work, we directly resolved the ordered configurations of p-xylenes (PXs)\nadsorbed in ZSM-5 frameworks by the scanning transmission electron microscopy\n(STEM) with the integrated differential phase contrast (iDPC) technique to\nidentify the host-guest vdW interactions. Based on these observations, we\nrevealed that the PXs in one straight channel modified the channel geometry\nwith a coherent orientation. And the adjacent straight channels were deformed\nup to 8.8% along the different directions corresponding to three dominant PX\nconfigurations, resulting a negligible overall expansion of ZSM-5 lattices.\nThen, we could also image the disorder and desorption of PXs in ZSM-5 channels\nduring the in situ heating. This work not only helped us to study the\nhost-guest vdW interactions and the sorption behaviors of PXs in ZSM-5, but\nalso provided an efficient tool for further imaging and studying other\nsingle-molecule behaviors under STEMs."
    },
    {
        "anchor": "Very thin (111) NiO epitaxial films grown on c-sapphire substrates by\n  pulsed laser deposition technique: (111)NiO epitaxial layers are grown on c-sapphire substrates by pulsed laser\ndeposition (PLD) technique. Structural and morphological properties of the\nfilms are studied using in-plane as well as out-of-plane high resolution X-ray\ndiffraction and atomic force microscopy techniques as functions of growth\ntemperature, oxygen pressure and the pulses count of the laser. The study shows\nthat continuous epitaxial films of thickness as low as 3 nm with high\ncrystalline quality, smooth surface and interface morphology can be grown by\nthis technique. The study also reveals the co-existence of 60{\\deg}-rotated\n(111) triangular domains of NiO in the film. The study also evidences the\npresence of a very low density of 60-degree dislocations in these films.\nDensity of screw and edge dislocations are also estimated to be quite low. It\nhas been found that growth-temperature, oxygen partial pressure and the film\nthickness can influence differently the density of various dislocation types.\nThese parameters are also found to affect significantly the strain developed in\nthe films.",
        "positive": "Scalable van der Waals epitaxy of tunable moir\u00e9 heterostructures: The unique physics found in moir\\'e superlattices of twisted or\nlattice-mismatched atomic layers hold great promise for future quantum\ntechnologies. However, twisted configurations are typically thermodynamically\nunfavorable, making the accurate twist angle control in direct growth\nimplausible. While rotationally aligned moir\\'e superlattices based on\nlattice-mismatched layers such as WSe2/WS2 can be synthesized, they lack the\ncritical tunability of the moir\\'e period and the moir\\'e formation mechanisms\nare not well-understood. Here, we report the scalable, thermodynamically driven\nvan der Waals epitaxy of stable moir\\'es with tunable period from 10 to 45\nnanometers, based on lattice mismatch engineering in two WSSe layers with\nadjustable chalcogens ratios. Contrarily to conventional epitaxy, where lattice\nmismatch induced stress hinders high-quality growth, we reveal the key role of\nbulk stress in moir\\'e formation, as well as its unique interplay with edge\nstress in shaping the moir\\'e growth modes. Moreover, the synthesized\nsuperlattices display tunable interlayer, and moir\\'e intralayer excitons. Our\nstudies unveil the unique epitaxial science of moir\\'e synthesis and lay the\nfoundations for moir\\'e-based technologies."
    },
    {
        "anchor": "Orbital occupation, local spin and exchange interactions in V2O3: We present the results of an LDA and LDA+U band structure study of the\nmonoclinic and the corundum phases of V2O3 and argue that the most prominent\n(spin 1/2) models used to describe the semiconductor metal transition are not\nvalid. Contrary to the generally accepted assumptions we find that the large on\nsite Coulomb and exchange interactions result in a total local spin of 1 rather\nthan 1/2 and especially an orbital occupation which removes the orbital\ndegeneracies and the freedom for orbital ordering. The calculated exchange\ninteraction parameters lead to a magnetic structure consistent with experiment\nagain without the need of orbital ordering. While the low-temperature\nmonoclinic distortion of the corundum crystal structure produces a very small\neffect on electronic structure of v2o3, the change of magnetic order leads to\ndrastic differences in band widths and band gaps. The low temperature\nmonoclinic phase clearly favors the experimentally observed magnetic structure,\nbut calculations for corundum crystal structure gave two consistent sets of\nexchange interaction parameters with nearly degenerate total energies\nsuggesting a kind of frustration in the paramagnetic phase. These results\nstrongly suggest that the phase transitions in V2O3 which is so often quoted as\nthe example of a S=1/2 Mott Hubbard system have a different origin. So back to\nthe drawing board!",
        "positive": "Renormalizing Antiferroelectric Nanostripes in\n  $\u03b2'-\\mathrm{In}_{2}\\mathrm{Se}_{3}$ via Optomechanics: Antiferroelectric (AFE) materials have received tremendous attention owing to\ntheir high energy conversion efficiency and good tunability. Recently, an\nexotic two-dimensional (2D) AFE material,\n$\\beta'-\\mathrm{In}_{2}\\mathrm{Se}_{3}$ monolayer that could host atomically\nthin AFE nanostripe domains has been experimentally synthesized and\ntheoretically examined. In this work, we apply first-principles calculations\nand theoretical estimations to predict that light irradiation can control the\nnanostripe width of such a system. We suggest that an intermediate\nnear-infrared light (below bandgap) could effectively harness the thermodynamic\nGibbs free energy, and the AFE nanostripe width will gradually reduce. We also\npropose to use an above bandgap linearly polarized light to generate AFE\nnanostripespecific photocurrent, providing an all-optical pump-probe setup for\nsuch AFE nanostripe width phase transitions."
    },
    {
        "anchor": "Nonlinear deformation and elasticity of BCC refractory metals and alloys: Application of isotropic pressure or uniaxial strain alters the elastic\nproperties of materials; sufficiently large strains can drive structural\ntransformations. Linear elasticity describes stability against infinitesimal\nstrains, while nonlinear elasticity describes the response to finite\ndeformations. It was previously shown that uniaxial strain along [100] drives\nrefractory metals and alloys towards mechanical instabilities. These include an\nextensional instability, and a symmetry-breaking orthorhombic distortion caused\nby a Jahn-Teller-Peierls instability that splays the cubic lattice vectors.\nHere, we analyze these transitions in depth. Eigenvalues and eigenvectors of\nthe Wallace tensor identify and classify linear instabilities in the presence\nof strain. We show that both instabilities are discontinuous, leading to\ndiscrete jumps in the lattice parameters. We provide physical intuition for the\ninstabilities by analyzing the changes in first principles energy, stress, bond\nlengths and angles upon application of strain. Electronic band structure\ncalculations show differential occupation of bonding and anti-bonding orbitals,\ndriven by the changing bond lengths and leading to the structural\ntransformations. Strain thresholds for these instabilities depend on the\nvalence electron count.",
        "positive": "First-principles study on the solute-induced low diffusion and\n  self-trapping of helium in fcc iron: The addition of alloying elements plays an essential role in helium (He)\nbehaviours produced by transmutation in metal alloys. Effects of solutes (Ni,\nCr, Ti, P, Si, C) on the behaviours of He and He-He pair in face-centred cube\n(fcc) iron have been investigated using first-principles calculations based on\ndensity functional theory (DFT). For the interactions of solutes and He, we\nfound that Ti, P, Si, and C attracts He is more potent than Ni and Cr in fcc\niron. We have determined the most stable configuration for the He-He pair,\nwhich is the Hesub-Hetetra pair with a binding energy of 1.60 eV. In\nconsidering the effect of solutes on the stability of the He-He pair, we have\nproposed a unique definition of binding energy. By applying the definition, we\nsuggest that Ti and P could weaken He self-trapping, and Cr and C are\nbeneficial for He self-trapping, while Ni is similar to the matrix Fe itself.\nFor the diffusion of He, which is the necessary process of forming the He\nbubble, we determined that the most stable interstitial He is in a tetrahedral\nsite and could migrate with the energy barrier of 0.16 eV in pure fcc iron. We\nfurther found that Ti and Si can increase the barrier to 0.18 and 0.20 eV; on\nthe contrary, Cr and P decrease the barrier to 0.10 and 0.06 eV, respectively.\nSummarizing the calculations, we conclude that Ti decreases while Cr increases\nthe diffusion and self-trapping of He in fcc iron."
    },
    {
        "anchor": "Premelting and formation of ice due to Casimir-Lifshitz interactions:\n  Impact of improved parameterization for materials: Recently, the premelting and formation of ice due to the Casimir-Lifshitz\ninteraction, proposed in early 1990s by Elbaum and Schick [Phys. Rev. Lett. 66,\n1713-1716 (1991)], have been generalized to diverse practical scenarios,\nyielding novel physical intuitions and possibilities of application for those\nphenomena. The properties of materials, in particular, the electrical\npermittivity and permeability, exert significant influences on the\nCasimir-Cifshitz energies and forces, and hence on the corresponding premelting\nand formation of ice. To address these influences in detail and explore the\nresulting physics, here we revisit and extend the analyses of previous work,\nwith both the dielectric data utilized there and the latest dielectric\nfunctions for ice and cold water. While our previous results are rederived, an\nerror there has also been spotted. For the four-layer cases considered by some\nof us, the existence of stable configurations depending on the initial\nconditions has been confirmed, and different types of stability corresponding\nto minima of the Casimir-Lifshitz free energy are demonstrated. As the new\ndielectric functions for ice and cold water deviate considerably from those\nused by Elbaum and Schick, their vital impacts on three- and four-layer\nconfigurations are therefore being reconsidered.",
        "positive": "Synthesis of water-soluble melanin: Melanins are promising materials for organic bioelectronics devices like\ntransistors, sensors and batteries. However, in general, melanin either natural\nor synthetic has low solubility in most solvents. In this study, the chemical\nstructural changes of melanin synthesized, by the auto oxidation of L-DOPA, are\nanalyzed for a new synthetic procedure using a reactor with oxygen pressure of\n4 atm. UV-Vis spectroscopy, FTIR, C-NMR, XPS and TEM are use to characterize\nthe material. Under oxygen pressure, the synthesis of melanin is accelerated\nand the polymer obtained is found to have higher carbonyl groups compared to\nconventional synthetic melanin. As a consequence it has higher homogeneity and\nis soluble in water. To explain these findings a reaction mechanism is proposed\nbased on current melanogenesis models."
    },
    {
        "anchor": "Structural, Vibrational and Electronic Properties of Single Layer\n  Hexagonal Crystals of Groups IV and V: Using first-principles density functional theory calculations, we investigate\na family of stable two-dimensional crystals with chemical formula $A_2B_2$,\nwhere $A$ and $B$ belong to groups IV and V, respectively ($A$ = C, Si, Ge, Sn,\nPb; $B$ = N, P, As, Sb, Bi). Two structural symmetries of hexagonal lattices\n$P\\bar{6}m2$ and $P\\bar{3}m1$ are shown to be dynamically stable, named as\n$\\alpha$- and $\\beta$-phases correspondingly. Both phases have similar cohesive\nenergies, and the $\\alpha$-phase is found to be energetically favorable for\nstructures except CP, CAs, CSb and CBi, for which the $\\beta$-phase is favored.\nThe effects of spin-orbit coupling and Hartree-Fock corrections to\nexchange-correlation are included to elucidate the electronic structures. All\nstructures are semiconductors except CBi and PbN, which have metallic\ncharacter. SiBi, GeBi and SnBi have direct band gaps, whereas the remaining\nsemiconductor structures have indirect band gaps. All structures have quartic\ndispersion in their valence bands, some of which make the valence band maximum\nand resemble a Mexican hat shape. SnAs and PbAs have purely quartic valence\nband edges, i.e. $E{\\sim}{-}\\alpha k^4$, a property reported for the first\ntime. The predicted materials are candidates for a variety of applications.\nOwing to their wide band gaps, CP, SiN, SiP, SiAs, GeN, GeP can find their\napplications in optoelectronics. The relative band positions qualify a number\nof the structures as suitable for water splitting, where CN and SiAs are\nfavorable at all pH values. Structures with quartic band edges are expected to\nbe efficient for thermoelectric applications.",
        "positive": "The dynamics of magnetic vortex states in a single permalloy\n  nanoparticle: We demonstrate a novel method allowing the study of the magnetic state\ndynamics of a single nanoparticle by means of electron transport measurements.\nElliptical 550 nm x 240 nm permalloy nanoparticles are wired with non-magnetic\nleads for magnetotransport measurements in the presence of a radio-frequency\n(RF) field. Their resistance exhibits sharp jumps due to the anisotropic\nmagnetoresistance even at room temperature. An RF field induces DC voltage\nacross the nanoparticle which can be partially depleted at a certain RF\nfrequency when a magnetic vortex core resonance is present. An application of\nan additional DC magnetic field eliminates the vortex and reinstates the\nunperturbed DC voltage level. The vortex core resonance frequencies are found\nand the smallest resonance widths are estimated to be less than 6 MHz."
    },
    {
        "anchor": "Accurate ab initio modeling of solid solution strengthening in high\n  entropy alloys: High entropy alloys (HEA) represent a class of materials with promising\nproperties, such as high strength and ductility, radiation damage tolerance,\netc. At the same time, a combinatorially large variety of compositions and a\ncomplex structure render them quite hard to study using conventional methods.\nIn this work, we present a computationally efficient methodology based on ab\ninitio calculations within the coherent potential approximation. To make the\nmethodology predictive, we apply an exchange-correlation correction to the\nequation of state and take into account thermal effects on the magnetic state\nand the equilibrium volume. The approach shows good agreement with available\nexperimental data on bulk properties of solid solutions. As a particular case,\nthe workflow is applied to a series of iron-group HEA to investigate their\nsolid solution strengthening within a parameter-free model based on the\neffective medium representation of an alloy. The results reveal intricate\ninteractions between alloy components, which we analyze by means of a simple\nmodel of local bonding. Thanks to its computational efficiency, the methodology\ncan be used as a basis for an adaptive learning workflow for optimal design of\nHEA.",
        "positive": "Comparative Density Functional Theory and Density Functional Tight\n  Binding Study of Arginine and Arginine-Rich Cell-Penetrating Peptide TAT\n  Adsorption on Anatase TiO2: We present a comparative Density Functional Theory (DFT) and Density\nFunctional Tight Binding (DFTB) study of geometries and electronic structures\nof arginine (Arg), arginine adsorbed on the anatase (101) surface of titania in\nseveral adsorption configurations, and of an arginine-rich cell penetrating\npeptide TAT and its adsorption on the surface of TiO2. Two DFTB\nparameterizations are considered, tiorg-0-1/mio-1-1 and matsci-0-3. While there\nis good agreement in the structures and relative energies of Arg and peptide\nconformers between DFT and DFTB, both adsorption geometries and energies are\nnoticeably different for Arg adsorbed on TiO2. The tiorg-0-1/mio-1-1\nparameterization performs better than matsci-0-3. We relate this difference to\nthe difference in electronic structures resulting from the two methods (DFT and\nDFTB) and specifically to the band alignment between the molecule and the\noxide. We show that the band alignment of TAT and of TiO2 modeled with DFTB is\nqualitatively correct but that with DFT using the PBE functional is not. This\nis specific to the modeling of large molecules where the HOMO is close to the\nconduction band of the oxide. We therefore report a case where the approximate\nDFT-based method - DFTB (with which the correct band structure can be\neffectively obtained) - performs better than the DFT itself with a functional\napproximation feasible for the modeling of large bio-inorganic interfaces, i.e.\nGGA (as opposed to hybrid functionals which are impractical at such a scale).\nOur results highlight the utility of the DFTB method for the modeling of\nbioinorganic interfaces not only from the CPU cost perspective but also from\nthe accuracy point of view."
    },
    {
        "anchor": "Ferromagnetism on an atom-thick and extended 2D-metal-organic framework: Ferromagnetism (FM) is the cornerstone of permanent magnets, data storage and\nother technologies that directly impact our everyday life by their\nimplementation in standard applications and devices. When downscaling bulk\nmaterials into their two-dimensional (2D) magnetic isotropic form, the\nMermin-Wagner theorem precludes this collective state mediated by short-range\nexchange interactions at finite temperatures. Interestingly, this prediction\nfails when significant magnetic anisotropy is present in the material, as\nrecently demonstrated in single layered van der Waals crystals. Before the\nlatter, single layer metal-organic frameworks (MOFs) grown on metallic supports\nwere one of the earliest candidates for achieving 2D-FM. Such high expectations\nwere based on the chemical and spacing control of the 2D-MOF magnetic centers,\nthe tunability of the organic linkers and the rich self-assembled architectures\ndisplayed. However, despite many attempts, extended FM in 2D-MOFs has been\nexperimentally elusive. In this work, we demonstrate that extended, cooperative\nFM takes place in an atom thick 2D-MOF consisting of 9,10-dicyanoanthracene\n(DCA) molecules and Fe adatoms grown on Au(111). We show this by means of an\nexperimental multitechnique approach that is endorsed by state-of-the art\nfirst-principles calculations. Particularly, this 2D ferromagnet follows a\nfirst order transition with TC ~ 35 K, which is driven by exchange interactions\nmainly through the molecular linkers (J=2 meV) and exhibits an out-of-plane\nsquare-like hysteresis loop. The strict periodicity of our 2D-MOF allows us to\nenvision the fabrication of ultra-dense single atom magnetic memories and opens\nthe way to explore periodic magnetic 2D-models that could considerably increase\nthe fundamental superparamagnetic limit.",
        "positive": "Variation of Contact Resonance Frequency during Domain Switching in PFM\n  Measurements for Ferroelectric Materials: Piezoresponse Force Spectroscopy (PFS) is a powerful method widely used for\nmeasuring the nanoscale ferroelectric responses of the materials. However, it\nis found that certain non-ferroelectric materials can also generate similar\nresponses from the PFS measurements due to many other factors, hence, it is\nbelieved that PFS alone is not sufficient to differentiate the ferroelectric\nand non-ferroelectric materials. On the other hands, this work shows that there\nare distinct differences in contact resonance frequency variation during the\nPFS measurements for ferroelectric and non-ferroelectric materials. Therefore,\na new, simple and effective method is proposed to differentiate the responses\nfrom the ferroelectric and non-ferroelectric materials, this new analysis uses\ncontact resonance frequency responses during the PFS measurements as a new\nparameter to differentiate the PFS measured responses from different materials."
    },
    {
        "anchor": "Theoretical and experimental evidence of level repulsion states and\n  evanescent modes in sonic crystal stubbed waveguides: The complex band structures calculated using the Extended Plane Wave\nExpansion (EPWE) reveal the presence of evanescent modes in periodic systems,\nnever predicted by the classical \\omega(\\vec{k}) methods, providing novel\ninterpretations of several phenomena as well as a complete picture of the\nsystem. In this work we theoretically and experimentally observe that in the\nranges of frequencies where a deaf band is traditionally predicted, an\nevanescent mode with the excitable symmetry appears changing drastically the\ninterpretation of the transmission properties. On the other hand, the\nsimplicity of the sonic crystals in which only the longitudinal polarization\ncan be excited, is used to interpret, without loss of generality, the level\nrepulsion between symmetric and antisymmetric bands in sonic crystals as the\npresence of an evanescent mode connecting both repelled bands. These evanescent\nmodes, obtained using EPWE, explain both the attenuation produced in this range\nof frequencies and the transfer of symmetry from one band to the other in good\nagreement with both experimental results and multiple scattering predictions.\nThus, the evanescent properties of the periodic system have been revealed\nnecessary for the design of new acoustic and electromagnetic applications based\non periodicity.",
        "positive": "Ab-initio study of different structures of CaC: Magnetism, Bonding, and\n  Lattice Dynamics: On the basis of ab-initio pseudopotential calculations, we study structural,\nmagnetic, dynamical, and mechanical properties of the hypothetical CaC ionic\ncompound in the rock-salt (RS), B2, zinc-blende (ZB), wurtzite (WZ), NiAs (NA),\nanti-NiAs (NA*), and CrB (B33) structures. It is argued that the ZB, WZ, NA,\nand RS structures are more ionic while the NA*, B2, and B33 structures are more\ncovalent systems. As a result of that, the nonmagnetic B33-CaC is the\nenergetically preferred system, while the more ionic structures prefer a\nferromagnetic ground state with high Fermi level spin polarization. The\nobserved ferromagnetism in the more ionic systems is attributed to the sharp\npartially filled $p$ states of carbon atom in the system. In the framework of\ndensity functional perturbation theory, the phonon spectra of these systems are\ncomputed and the observed dynamical instabilities of the NA* and B2 structures\nare explained in terms of the covalent bonds between carbon atoms. The\ncalculated Helmholtz and Enthalpy free energies indicate the highest stability\nof the B33 structure in a wide range of temperatures and pressures. Among the\nferromagnetic structures, RS-CaC and ZB-CaC are reported, respectively, to be\nthe most and the least metastable systems in various thermodynamics conditions.\nSeveral mechanical properties of the dynamically stable structures of CaC are\ndetermined from their phonon spectra."
    },
    {
        "anchor": "Charge-carrier complexes in monolayer semiconductors: The photoluminescence (PL) spectra of monolayer (1L) semiconductors feature\npeaks ascribed to different charge-carrier complexes. We perform diffusion\nquantum Monte Carlo simulations of the binding energies of these complexes and\nexamine their response to electric and magnetic fields. We focus on quintons\n(charged biexcitons), since they are the largest free charge-carrier complexes\nin transition-metal dichalcogenides (TMDs). We examine the accuracy of the\nRytova-Keldysh interaction potential between charges by comparing the binding\nenergies of charge-carrier complexes in 1L-TMDs with results obtained using\n$\\textit{ab initio}$ interaction potentials. Magnetic fields$<8$T change the\nbinding energies (BEs) by$\\sim0.2$ meV,T$^{-1}$, in agreement with experiments,\nwith the BE variations of different complexes being very similar. Our results\nwill help identify charge complexes in the PL spectra of 1L-semiconductors",
        "positive": "Pinning of extended dislocations in atomically disordered crystals: In recent years there has been renewed interest in the behavior of\ndislocations in crystals that exhibit strong atomic scale disorder, as typical\nof compositionally complex single phase alloys. The behavior of dislocations in\nsuch crystals has been often studied in the framework of elastic manifold\npinning in disordered systems. Here we discuss modifications of this framework\nthat may need to be adapted when dealing with extended dislocations that split\ninto widely separated partials. We demonstrate that the presence of a stacking\nfault gives rise to an additional stress scale that needs to be compared with\nthe pinning stress of elastic manifold theory to decide whether the partials\nare pinned individually or the dislocation is pinned as a whole. For the case\nof weakly interacting partial dislocations, we demonstrate the existence of\nmultiple metastable states at stresses below the depinning threshold and\nanalyze the stress evolution of the stacking fault width during loading. In\naddition we investigate how geometrical constraints can modulate the\ndislocation-solute interaction and enhance the pinning stress. We compare our\ntheoretical arguments with results of atomistic and discrete (partial)\ndislocation dynamics (D(P)DD) simulations."
    },
    {
        "anchor": "Optimizing nucleation layers for the integration of ferroelectric HZO on\n  CVD-grown graphene: Direct integration of ferroelectric Hf0.5Zr0.5O2 (HZO) on the inert surface\nof graphene is challenging. Here, using nucleation layers to promote atomic\nlayer deposition of HZO was investigated. Different metals were deposited as\nnucleation layers via dc sputtering. Ta, which oxidizes in air to form a\nsub-stoichiometric oxide, was compared to Pt, which offers a more stable\nelectrode. For thicker interlayers, Ta leads to unstable switching behavior of\nthe HZO film. Conversely, at smaller thicknesses, a higher Pr can be achieved\nwith an oxidized Ta interlayer. In both cases, Pt offers higher endurance. The\nchoice of interlayer may strongly depend on the required application.",
        "positive": "Kondo effect goes anisotropic in vanadate oxide superlattices: We study the transport properties in SrVO3/LaVO3 (SVO/LVO) superlattices\ndeposited on SrTiO3 (STO) substrates. We show that the electronic conduction\noccurs in the metallic LVO layers with a galvanomagnetism typical of a 2D Fermi\nsurface. In addition, a Kondo-like component appears in both the thermal\nvariation of resistivity and the magnetoresistance. Surprisingly, in this\nsystem where the STO interface does not contribute to the measured conduction,\nthe Kondo correction is strongly anisotropic. We show that the growth\ntemperature allows a direct control of this contribution. Finally, the key role\nof vanadium mixed valency stabilized by oxygen vacancies is enlightened."
    },
    {
        "anchor": "Effect of salt concentration on the solubility, ion-dynamics, and\n  transport properties of dissolved vanadium ions in lithium-ion battery\n  electrolytes: Generalized solubility limit approach (Part II): In this article, we study the transport properties of superconcentrated\nelectrolytes using Molecular Dynamics simulations, which have been shown\nexperimentally to retard elemental dissolution in vanadium containing cathode\nmaterials. Five compositions between one and seven molar lithium\nbis(trifluoromethanesulfonyl)imide in 1,3-Dioxolane and 1,2-Dimethoxyethane\nsolvent mixture are studied using non-polarizable Optimized Potentials for\nLiquid Simulations - All Atom force field. The simulated physico-chemical\nproperties such as ionic conductivity, self-diffusion coefficients, and density\nare observed to match well with the results obtained through experiments.\nRadial Distribution Function analysis reveals a strong co-ordination between\nsalt anions and vanadium cations as the electrolyte transitions from a\nsalt-in-solvent type to solvent-in-salt type electrolyte. A high anion content\nin the first solvation shell of vanadium cations is observed for\nsolvent-in-salt type electrolytes, through ion-clustering calculations.\nSolvation free energy calculations using Free Energy Perturbation method\nindicate that the active material dissolution should be retarded by using\nsuperconcentrated electrolytes. Ion-dynamics of the clusters reveal that\nvanadium cation transport occurs against its concentration gradient due to\nstrong coulombic interactions with the salt anions in superconcentrated\nelectrolytes. The improvement in the cycleability of several vanadium\ncontaining cathode materials provides a robust proof for the theoretical\nframework described in this manuscript.",
        "positive": "Structural and Optoelectronic Behaviour of Copper Doped Cs2AgInCl6\n  Double Perovskite: A DFT Investigation: Recently, direct bandgap double perovskites are becoming more popular among\nphotovoltaic research community owing to their potential to address issues of\nlead (Pb) toxicity and structural instability inherent in lead halide (simple)\nperovskites. In this study, In-Ag based direct bandgap double perovskite,\nCs2AgInCl6 (CAIC), is treated with transition metal doping to improve the\noptoelectronic properties of the material. Investigations of structural and\noptoelectronic properties of Cu-doped CAIC, Cs2Ag(1-x)CuxInCl6, are done using\nab-initio calculations with density functional theory (DFT) and virtual crystal\napproximation (VCA). Our calculations show that with increasing Cu content, the\noptimized lattice parameter and direct bandgap of Cs2Ag(1-x)CuxInCl6 decrease\nfollowing linear and quadratic functions respectively, while the bulk modulus\nincreases following a quadratic function. The photo-absorption coefficient,\noptical conductivity and other optical parameters of interest are also\ncomputed, indicating enhanced absorption and conductivity for higher Cu\ncontents. Based on our results, transition metal (Cu) doping is a viable means\nof treating double perovskites - by tuning their optoelectronic properties\nsuitable for an extensive range of photovoltaics, solar cells and\noptoelectronics."
    },
    {
        "anchor": "Al20+ does melt, albeit above the bulk melting temperature of aluminium: Employing first principles parallel tempering molecular dynamics in the\nmicrocanonical ensemble, we report the presence of a clear solid-liquid-like\nmelting transition in Al20+ clusters, not found in experiments. The phase\ntransition temperature obtained from the multiple histogram method is 993 K, 60\nK above the melting point of aluminium. Root mean squared bond length\nfluctuation, the velocity auto-correlation function and the corresponding power\nspectrum further confirm the phase transition from a solid-like to liquid-like\nphase. Atoms-In-Molecules analysis shows a strong charge segregation between\nthe internal and surface atoms, with negatively charged internal atoms and\npositive charge at the surface. Analysis of the calculated diffusion\ncoefficient indicates different mobilities of the internal and surface atoms in\nthe solid-like phase, and the differences between the environment of the\ninternal atoms in these clusters with that of the bulk atoms suggest a physical\npicture for the origin of greater-than-bulk melting temperatures.",
        "positive": "Anharmonic interatomic force constants and thermal conductivity from\n  Gr\u00fcneisen parameters: an application to graphene: Phonon-mediated thermal conductivity, which is of great technological\nrelevance, fundamentally arises due to anharmonic scattering from interatomic\npotentials. Despite its prevalence, accurate first-principles calculations of\nthermal conductivity remain challenging, primarily due to the high\ncomputational cost of anharmonic interatomic force constant (IFCs)\ncalculations. Meanwhile, the related anharmonic phenomenon of thermal expansion\nis much more tractable, being computable from the Gr\\\"uneisen parameters\nassociated with phonon frequency shifts due to crystal deformations. In this\nwork, we propose a novel approach for computing the largest cubic IFCs from the\nGr\\\"uneisen parameter data. This allows an approximate determination of the\nthermal conductivity via a much less expensive route. The key insight is that\nalthough the Gr\\\"uneisen parameters cannot possibly contain all the information\non the cubic IFCs, being derivable from spatially uniform deformations, they\ncan still unambiguously and accurately determine the largest and most\nphysically relevant ones. By fitting the anisotropic Gr\\\"uneisen parameter data\nalong judiciously designed deformations, we can deduce (i.e., reverse engineer)\nthe dominant cubic IFCs and estimate three-phonon scattering amplitudes. We\nillustrate our approach by explicitly computing the largest cubic IFCs and\nthermal conductivity of graphene, especially for its out-of-plane (flexural)\nmodes that exhibit anomalously large anharmonic shifts and thermal conductivity\ncontributions. Our calculations on graphene not only exhibits reasonable\nagreement with established DFT results, but also presents a pedagogical\nopportunity for introducing an elegant analytic treatment of the Gr\\\"uneisen\nparameters of generic two-band models. Our approach can be readily extended to\nmore complicated crystalline materials with nontrivial anharmonic lattice\neffects."
    },
    {
        "anchor": "Van der Waals forces control ferroelectric-antiferroelectric ordering in\n  ABP2X6 laminar materials: We show how van der Waals (vdW) forces outcompete covalent and ionic forces\nto control ferroelectric ordering in CuInP2S6 nanoflakes as well as in CuInP2S6\nand CuBiP2Se6 crystals. While the self-assembly of these 2D layered materials\nis clearly controlled by vdW effects, this result indicates that the internal\nlayer structure is also similarly controlled. Using up to 14 first-principles\ncomputational methods, we predict that the bilayers of both materials should be\nantiferroelectric. However, antiferroelectric nanoflakes and bulk materials are\nshown to embody two fundamentally different types of inter-layer interactions,\nwith vdW forces strongly favouring one and strongly disfavouring the other\ncompared to ferroelectric ordering. Strong specific vdW interactions involving\nthe Cu atoms control this effect. Thickness-dependent significant cancellation\nof these two large opposing vdW contributions results in a small net effect\nthat interacts with weak ionic contributions to control ferroelectric ordering.",
        "positive": "Raman scattering study of delafossite magnetoelectric multiferroic\n  compounds: CuFeO2 and CuCrO2: Ultrasonic velocity measurements on the magnetoelectric multiferroic compound\nCuFeO2 reveal that the antiferromagnetic transition observed at TN1 = 14 K\nmight be induced by an R-3m -> C2/m pseudoproper ferroelastic transition (G.\nQuirion, M. J. Tagore, M. L. Plumer, O. A. Petrenko, Phys. Rev. B 77, 094111\n(2008)). In that case, the group theory states that the order parameter\nassociated with the structural transition must belong to a two dimensional\nirreducible representation Eg (x^2 - y^2, xy). Since this type of transition\ncan be driven by a Raman Eg mode, we performed Raman scattering measurements on\nCuFeO2 between 5 K and 290 K. Considering that the isostructural multiferroic\ncompound CuCrO2 might show similar structural deformations at the\nantiferromagnetic transition TN1 = 24.3 K, Raman measurements have also been\nperformed for comparison. At ambient temperature, the Raman modes in CuFeO2 are\nobserved at omega_Eg = 352 cm^-1 and omega_Ag = 692 cm^-1, while these modes\nare detected at omega_E_g = 457 cm^-1 and omega_Ag = 709 cm^-1 in CuCrO2. The\nanalysis of the temperature dependence of modes shows that the frequency of all\nmodes increases down to 5 K. This typical behavior can be attributed to\nanharmonic phonon-phonon interactions. These results clearly indicate that none\nof the Raman active modes observed in CuFeO2 and CuCrO2 drive the pseudoproper\nferroelastic transition observed at the N\\'eel temperature TN1. Finally, a\nbroad band at about 550 cm^-1 observed in the magnetoelectric phase of CuCrO2\nbelow TN2 could be attributed to a magnon mode."
    },
    {
        "anchor": "Comment on Two-dimensional porous graphitic carbon nitride C6N7\n  monolayer: First-principles calculations [Appl. Phys. Lett. 2021, 119,\n  142102]: Recently, Bafekry et al. [Appl. Phys. Lett. 119, 142102 (2021)] reported\ntheir density functional theory (DFT) results on the elastic constants of a\nnovel C6N7 monolayer. They predicted a very soft elastic modulus of 36.29 GPa\nfor the C6N7 monolayer, which is remarkably low for carbon-nitride 2D lattices.\nUsing DFT calculations, we predict a remarkably higher elastic modulus of 267\nGPa for this monolayer. The maximum tensile strength is also predicted to be\n20.5 GPa, revealing the outstanding mechanical properties of the C6N7\nmonolayer.",
        "positive": "Atomistic $k.p$ theory: Pseudopotentials, tight-binding models, and $k\\cdot p$ theory have stood for\nmany years as the standard techniques for computing electronic states in\ncrystalline solids. Here we present the first new method in decades, which we\ncall atomistic $k\\cdot p$ theory. In its usual formulation, $k\\cdot p$ theory\nhas the advantage of depending on parameters that are directly related to\nexperimentally measured quantities, however it is insensitive to the locations\nof individual atoms. We construct an atomistic $k\\cdot p$ theory by defining\nenvelope functions on a grid matching the crystal lattice. The model parameters\nare matrix elements which are obtained from experimental results or {\\it ab\ninitio} wave functions in a simple way. This is in contrast to the other\natomistic approaches in which parameters are fit to reproduce a desired\ndispersion and are not expressible in terms of fundamental quantities. This\nfitting is often very difficult. We illustrate our method by constructing a\nfour-band atomistic model for a diamond/zincblende crystal and show that it is\nequivalent to the $sp^3$ tight-binding model. We can thus directly derive the\nparameters in the $sp^3$ tight-binding model from experimental data. We then\ntake the atomistic limit of the widely used eight-band Kane model and compute\nthe band structures for all III-V semiconductors not containing nitrogen or\nboron using parameters fit to experimental data. Our new approach extends\n$k\\cdot p$ theory to problems in which atomistic precision is required, such as\nimpurities, alloys, polytypes, and interfaces. It also provides a new approach\nto multiscale modeling by allowing continuum and atomistic $k\\cdot p$ models to\nbe combined in the same system."
    },
    {
        "anchor": "Vibrational and vibronic structure of isolated point defects: the\n  nitrogen-vacancy center in diamond: We present a theoretical study of vibrational and vibronic properties of a\npoint defect in the dilute limit by means of first-principles density\nfunctional theory calculations. As an exemplar we choose the negatively charged\nnitrogen-vacancy center, a solid-state system that has served as a testbed for\nmany protocols of quantum technology. We achieve low effective concentrations\nof defects by constructing dynamical matrices of large supercells containing\ntens of thousands of atoms. The main goal of the paper is to calculate\nluminescence and absorption lineshapes due to coupling to vibrational degrees\nof freedom. The coupling to symmetric $a_1$ modes is computed via the\nHuang-Rhys theory. Importantly, to include a nontrivial contribution of $e$\nmodes we develop an effective methodology to solve the multi-mode $E \\otimes e$\nJahn-Teller problem. Our results show that for NV centers in diamond a proper\ntreatment of $e$ modes is particularly important for absorption. We obtain good\nagreement with experiment for both luminescence and absorption. Finally, the\nremaining shortcomings of the theoretical approach are critically reviewed. The\npresented theoretical approach will benefit identification and future studies\nof point defects in solids.",
        "positive": "Thermodynamic Model of Liquid-Liquid Phase Equilibrium in Solutions of\n  Alkanethiol-Coated Nanoparticles: A thermodynamic model for a mixture of alkanethiol-coated nanoparticles (NPs)\nand low molecular weight (non-polymeric) solvent is developed, and calculations\nof liquid-liquid phase equilibrium for different values of NP core radius,\nalkanethiol chain length, solvent molar volume and alkanethiol-solvent\ninteraction parameter, are presented. The model takes into account the swelling\nof the organic coronas and the dispersion of particles with swollen coronas in\nthe solvent. The energetic interaction between alkyl chains and solvent is\nconsidered, both within the corona and between the outer alkyl segments and\nfree solvent. Swelling involves mixing of alkanethiol chains and solvent in the\ncorona and stretching of the organic chains. Dispersion considers an entropic\ncontribution based on Carnahan Starling equation of state and an enthalpic term\ncalculated considering the surface contacts between alkyl segments placed in\nthe external boundary of the corona and the molecules of free solvent. Two\ndifferent kinds of phase equilibrium are found. One of them, observed at high\nvalues of the interaction parameter, is the typical liquid-liquid equilibrium\nfor compact NPs in a poor solvent where a complete phase separation is observed\nwhen cooling (increasing the interaction parameter). The second liquid-liquid\nequilibrium is observed at low values of the interaction parameter, where\nswelling of coronas is favored. In this region two different phases co-exist,\none more concentrated in NPs that exhibit relatively compact coronas and the\nother one more diluted in NPs with extended coronas. In diluted solutions of\nNPs the deswelling of the fully extended coronas takes place abruptly in a very\nsmall temperature range, leading to a solution of compact NPs. This critical\ntransition might find practical applications similar to those found for the\nabrupt shrinkage of hydrogels at a critical temperature."
    },
    {
        "anchor": "Unintentional F doping of the surface of SrTiO3(001) etched in HF acid\n  -- structure and electronic properties: We show that the HF acid etch commonly used to prepare SrTiO3(001) for\nheteroepitaxial growth of complex oxides results in a non-negligible level of F\ndoping within the terminal surface layer of TiO2. Using a combination of x-ray\nphotoelectron spectroscopy and scanned angle x-ray photoelectron diffraction,\nwe determine that on average ~13 % of the O anions in the surface layer are\nreplaced by F, but that F does not occupy O sites in deeper layers. Despite\nthis perturbation to the surface, the Fermi level remains unpinned, and the\nsurface-state density, which determines the amount of band bending, is driven\nby factors other than F doping. The presence of F at the STO surface is\nexpected to result in lower electron mobilities at complex oxide\nheterojunctions involving STO substrates because of impurity scattering.\nUnintentional F doping can be substantially reduced by replacing the HF-etch\nstep with a boil in deionized water, which in conjunction with an oxygen tube\nfurnace anneal, leaves the surface flat and TiO2 terminated.",
        "positive": "A simple environment-dependent overlap potential and Cauchy violation in\n  solid argon: We develop an analytic and environment-dependent interatomic potential for\nthe overlap repulsion in solid argon, based on an approximate treatment of the\nnon-orthogonal Tight-Binding theory for the closed-shell systems. The present\nmodel can well reproduce the observed elastic properties of solid argon\nincluding Cauchy violation at high pressures, yet very simple. A useful and\nnovel analysis is given to show how the elastic properties are related to the\nenvironment-dependence incorporated into a generic pairwise potential. The\npresent study has a close link to the broad field of computational materials\nscience, in which the inclusion of environment dependence in short-ranged\nrepulsive part of a potential model is sometimes crucial in predicting the\nelastic properties correctly."
    },
    {
        "anchor": "A polymorphous band structure model of gapping in the anti-ferromagnetic\n  and paramagnetic phases of the Mott insulators MnO, FeO, CoO, and NiO: A band structure description of the observed large band gaps and moments in\nboth the antiferromagnetic (AFM) and paramagnetic (PM) phases of the classic\nNaCl-structure Mott insulators MnO, FeO, CoO, and NiO is provided by ordinary,\nsingle-determinant density functional theory method. As noted by previous\nauthors, the ordered AFM phases already show in band theory significant band\ngaps. However, for the disordered PM phases the commonly used band model has\nbeen to assume the macroscopically observed, averaged NaCl structure, where all\ntransition metal sites are forced to be symmetry-equivalent (a monomorphous\ndescription); for the PM phase this forces zero moment on an atom by atom\nbasis, thus producing a gapless PM state, in sharp conflict with experiment.\nInstead, we allow larger NaCl-type supercells where each TM site can have\ndifferent local bonding and spin environments (a polymorphous description) and\nthus the geometric flexibility to acquire symmetry-lowering distortions that\nlower the total energy and can break the symmetry of the d orbitals. The\nexistence of a distribution of different local spin and bonding environments\nallows large on-site magnetic moments to develop spontaneously in the DFT+U\ncalculations leading to significant (1-3 eV) band gaps in the AFM, FM, and PM\nphases of the classic Mott insulators MnO, FeO, CoO, and NiO. We adapt to the\nspin disordered configurations in the PM phases the \"special quasi-random\nstructure\" whereby supercell approximants which represent the best random\nconfiguration average for finite supercells of a given lattice symmetry are\nconstructed. Thus, avoiding a monomorphous description of the disordered\nmagnetic phases allows even ordinary DFT+U, which represents the N electron\nsystem with a single-determinant wavefunction, to describe the gapping not only\nin the AFM phases but also in the PM phases of MnO, FeO, CoO, and NiO.",
        "positive": "Work Function Characterization of the Directionally Solidified LaB6 VB2\n  Eutectic: With its low work function and high mechanical strength, the LaB6/VB2\neutectic system is an interesting candidate for high performance thermionic\nemitters. For the development of device applications, it is important to\nunderstand the origin, value, and spatial distribution of the work function in\nthis system. Here we combine thermal emission electron microscopy and low\nenergy electron microscopy with Auger electron spectroscopy and physical vapour\ndeposition of the constituent elements to explore physical and chemical\nconditions governing the work function of these surfaces. Our results include\nthe observation that work function is lower (and emission intensity is higher)\non VB2 inclusions than on the LaB6 matrix. We also observe that the deposition\nof atomic monolayer doses of vanadium results in surprisingly significant\nlowering of the work function with values as low as 1.1 eV."
    },
    {
        "anchor": "Photoionization of negatively charged NV centers in diamond: theory and\n  ab initio calculations: We present ab-initio calculations of photoionization thresholds and cross\nsections of the negatively charged nitrogen-vacancy (NV) center in diamond from\nthe ground $^{3}\\!A_2$ and the excited $^{3}\\!E$ states. We show that after the\nionization from the $^{3}\\!E$ level the NV center transitions into the\nmetastable $^{4}\\!A_2$ electronic state of the neutral defect. We reveal how\nspin polarization of $\\mathrm{NV}^{-}$ gives rise to spin polarization of the\n$^{4}\\!A_2$ state, providing an explanation of electron spin resonance\nexperiments. We obtain smooth photoionization cross sections by employing dense\n$k$-point meshes for the Brillouin zone integration together with the band\nunfolding technique to rectify the distortions of the band structure induced by\nartificial periodicity of the supercell approach. Our calculations provide a\ncomprehensive picture of photoionization mechanisms of $\\mathrm{NV}^{-}$. They\nwill be useful in interpreting and designing experiments on charge-state\ndynamics at NV centers. In particular, we offer a consistent explanation of\nrecent results of spin-to-charge conversion of NV centers.",
        "positive": "Atomistic Mechanisms of Mg Insertion Reactions in Group XIV Anodes for\n  Mg-Ion Batteries: Magnesium (Mg) metal has been widely explored as an anode material for Mg-ion\nbatteries (MIBs) owing to its large specific capacity and dendrite-free\noperation. However critical challenges, such as the formation of passivation\nlayers during battery operation and anode-electrolyte-cathode\nincompatibilities, limit the practical application of Mg-metal anodes for MIBs.\nMotivated by the promise of group XIV elements (namely Si, Ge and Sn) as anodes\nfor lithium- and sodium-ion batteries, here we conduct systematic first\nprinciples calculations to explore the thermodynamics and kinetics of group XIV\nanodes for Mg-ion batteries, and to identify the atomistic mechanisms of the\nelectrochemical insertion reactions of Mg ions. We confirm the formation of\namorphous MgxX phases (where X = Si, Ge, Sn) in anodes via the breaking of the\nstronger X-X bonding network replaced by weaker Mg-X bonding. Mg ions have\nhigher diffusivities in Ge and Sn anodes than in Si, resulting from weaker\nGe-Ge and Sn-Sn bonding networks. In addition, we identify thermodynamic\ninstabilities of MgxX that require a small overpotential to avoid aggregation\n(plating) of Mg at anode/electrolyte interfaces. Such comprehensive first\nprinciples calculations demonstrate that amorphous Ge and crystalline Sn can be\npotentially effective anodes for practical applications in Mg-ion batteries."
    },
    {
        "anchor": "On the accuracy of DFT exchange-correlation functionals for H bonds in\n  small water clusters II: The water hexamer and van der Waals interactions: Second order Moeller-Plesset perturbation theory (MP2) at the complete basis\nset (CBS) limit and diffusion quantum Monte Carlo (DMC) are used to examine\nseveral low energy isomers of the water hexamer. Both approaches predict the\nso-called \"prism\" to be the lowest energy isomer, followed by \"cage\", \"book\",\nand \"cyclic\" isomers. The energies of the four isomers are very similar, all\nbeing within 10-15 meV/H2O. This reference data is then used to evaluate the\nperformance of several density-functional theory (DFT) exchange-correlation\n(xc) functionals. A subset of the xc functionals tested for smaller water\nclusters [I: Santra et al., J. Chem. Phys. 127, 184104 (2007)] has been\nconsidered. Whilst certain functionals do a reasonable job at predicting the\nabsolute dissociation energies of the various isomers (coming within 10-20\nmeV/H2O), none predict the correct energetic ordering of the four isomers, nor\ndoes any predict the correct low total energy isomer. All xc functionals tested\neither predict the book or cyclic isomers to have the largest dissociation\nenergies. A many-body decomposition of the total interaction energies within\nthe hexamers leads to the conclusion that the failure lies in the poor\ndescription of van der Waals (dispersion) forces in the xc functionals\nconsidered. It is shown that the addition of an empirical pairwise (attractive)\nC6/R6 correction to certain functionals allows for an improved energetic\nordering of the hexamers. The relevance of these results to density-functional\nsimulations of liquid water is also briefly discussed.",
        "positive": "Importance of non-parabolic band effects in the thermoelectric\n  properties of semiconductors: We present an analysis of the thermoelectric properties of of $n$-type GeTe\nand SnTe in relation to the lead chalcogenides PbTe and PbSe. We find that the\nsingly degenerate conduction bands of semiconducting GeTe and SnTe are highly\nnon-ellipsoidal, even very close to the band edges. This leads to isoenergy\nsurfaces with a strongly corrugated shape that is clearly evident at carrier\nconcentrations well below 0.005 $e$ per formula unit (7 - 9 $\\times$\n10$^{19}$cm$^{-3}$ depending on material) Analysis within Boltzmann theory\nsuggests that this corrugation may be favorable for the thermoelectric\ntransport. Our calculations also indicate that values of the power factor for\nthese two materials may well exceed those of PbTe and PbSe. As a result these\nmaterials may exhibit $n$-type performance exceeding that of the lead\nchalcogenides."
    },
    {
        "anchor": "Exciton polarization, fine structure splitting and quantum dot asymmetry\n  under uniaxial stress: We derive a general relation between the fine structure splitting (FSS) and\nthe exciton polarization angle of self-assembled quantum dots (QDs) under\nuniaxial stress. We show that the FSS lower bound under external stress can be\npredicted by the exciton polarization angle and FSS under zero stress. The\ncritical stress can also be determined by monitoring the change in exciton\npolarization angle. We confirm the theory by performing atomistic\npseudopotential calculations for the InAs/GaAs QDs. The work provides a deep\ninsight into the dots asymmetry and their optical properties, and a useful\nguide in selecting QDs with smallest FSS which are crucial in entangled photon\nsources applications.",
        "positive": "Optical properties of metamorphic type-I\n  InAs$_{1-x}$Sb$_{x}$/Al$_{y}$In$_{1-y}$As quantum wells grown on GaAs for the\n  mid-infrared spectral range: We analyse the optical properties of\nInAs$_{1-x}$Sb$_{x}$/Al$_{y}$In$_{1-y}$As quantum wells (QWs) grown by\nmolecular beam epitaxy on relaxed Al$_{y}$In$_{1-y}$As metamorphic buffer\nlayers (MBLs) using GaAs substrates. The use of Al$_{y}$In$_{1-y}$As MBLs\nallows for the growth of QWs having large type-I band offsets, and emission\nwavelengths $> 3$ $\\mu$m. Photoluminescence (PL) measurements for QWs having Sb\ncompositions up to $x = 10$\\% demonstrate strong room temperature emission up\nto 3.4 $\\mu$m, as well as enhancement of the PL intensity with increasing\nwavelength. To quantify the trends in the measured PL we calculate the QW\nspontaneous emission, using a theoretical model based on an 8-band $\\vec{k}\n\\cdot \\vec{p}$ Hamiltonian. The theoretical calculations, which are in good\nagreement with experiment, identify that the observed enhancement in PL\nintensity with increasing wavelength is associated with the impact of\ncompressive strain on the QW valence band structure. Our results highlight the\npotential of type-I InAs$_{1-x}$Sb$_{x}$/Al$_{y}$In$_{1-y}$As metamorphic QWs\nto address several limitations associated with existing heterostructures\noperating in the mid-infrared, establishing these novel heterostructures as a\nsuitable platform for the development of mid-infrared light-emitting diodes."
    },
    {
        "anchor": "Theory of Weak Localization in Ferromagnetic (Ga,Mn)As: We study quantum interference corrections to the conductivity in (Ga,Mn)As\nferromagnetic semiconductors using a model with disordered valence band holes\ncoupled to localized Mn moments through a p-d kinetic-exchange interaction. We\nfind that at Mn concentrations above 1% quantum interference corrections lead\nto negative magnetoresistance, i.e. to weak localization (WL) rather than weak\nantilocalization (WAL). Our work highlights key qualitative differences between\n(Ga,Mn)As and previously studied toy model systems, and pinpoints the mechanism\nby which exchange splitting in the ferromagnetic state converts valence band\nWAL into WL. We comment on recent experimental studies and theoretical analyses\nof low-temperature magnetoresistance in (Ga,Mn)As which have been variously\ninterpreted as implying both WL and WAL and as requiring an impurity-band\ninterpretation of transport in metallic (Ga,Mn)As.",
        "positive": "Liquid-Metal-Enabled Synthesis of Aluminum-Containing III-Nitrides by\n  Plasma-Assisted Molecular Beam Epitaxy: Nitride films are promising for advanced optoelectronic and electronic device\napplications. However, some challenges continue to impede development of high\naluminum-containing devices. The two major difficulties are growth of high\ncrystalline quality films with aluminum-rich compositions, and efficiently\ndoping such films p-type. These problems have severely limited use of\naluminum-rich nitride films grown by molecular beam epitaxy. A way around these\nproblems is through use of a liquid-metal-enabled approach to molecular beam\nepitaxy. Although the presence of a liquid metal layer at the growth front is\nreminiscent of conventional liquid phase epitaxy, this approach is different in\nits details. Conventional liquid epitaxy is a near-thermodynamic equilibrium\nprocess which liquid-metal assisted molecular beam epitaxy is not. Growth of\naluminum-rich nitrides is primarily driven by the kinetics of the molecular\nvapor fluxes, and the surface diffusion of adatoms through a liquid metal layer\nbefore incorporation. This paper reports on growth of high crystalline quality\nand highly doped aluminum-containing nitride films. Measured optical and\nelectrical characterization data show that the approach is viable for growth of\natomically smooth aluminum-containing nitride heterostructures. Extremely high\np-type doping of up to $6 \\times 10$$^{17}$ cm$^{-3}$ and n-type doping of up\nto $1 \\times 10$$^{20}$ cm$^{-3}$ in Al$_{0.7}$Ga$_{0.3}$N films was achieved.\nUse of these metal-rich conditions is expected to have a significant impact on\nhigh efficiency and high power optoelectronic and electronic devices that\nrequire both high crystalline quality and highly doped (Al,Ga)N films."
    },
    {
        "anchor": "Charge transfer, confinement, and ferromagnetism in LaMnO$_3$/LaNiO$_3$\n  (001)-superlattice: Using first-principles density functional theory calculations, we\ninvestigated the electronic structure and magnetic properties of\n(LaMnO$_3$)$_m$/(LaNiO$_3$)$_n$ superlattices stacked along (001)-direction.\nThe electrons are transferred from Mn to Ni, and the magnetic moments are\ninduced at Ni sites that are paramagnetic in bulk and other types of\nsuperlattices. The size of induced moment is linearly proportional to the\namount of transferred electrons, but it is larger than the net charge transfer\nbecause the spin and orbital directions play important roles and complicate the\ntransfer process. The charge transfer and magnetic properties of the ($m$,$n$)\nsuperlattice can be controlled by changing the $m/n$ ratio. Considering the\nferromagnetic couplings between Mn and Ni spins and the charge transfer\ncharacteristic, we propose the (2,1) superlattice as the largest moment\nsuperlattice carrying $\\sim8\\mu_B$ per formula unit.",
        "positive": "Excitonic Effects in the Optical Spectra of Lithium metasilicate\n  (Li2SiO3): The Li2SiO3 compound, a ternary electrolyte compound of Lithium-ion based\nbatteries, exhibits unique geometric and band structures, an atom-dominated\nenergy spectrum, charge densities distributions, atom and orbital-projected\ndensity of states, and strong optical responses. The state-of-the-art analysis,\nbased on an ab-initio simulation, have successfully confirmed the concise\nphysical/chemical picture and the orbital bonding in Li-O and Si-O bonds.\nAdditionally, the unusual optical response behavior includes a large redshift\nof the onset frequency due to the extremely strong excitonic effect, the\npolarization of optical properties along three-directions, 22 optical\nexcitations structures and the most prominent plasmon mode in terms of the\ndielectric functions, energy loss functions, absorption coefficients, and\nreflectance spectra. The close connections of electronic and optical properties\ncan identify a specific orbital hybridization for each distinct excitation\nchannel. The developed theoretical framework will be very appropriate for fully\ncomprehending the diverse phenomena of cathode/electrolyte/anode materials in\nion-based batteries."
    },
    {
        "anchor": "Theory of Brillouin Light Scattering from Ferromagnetic Nanospheres: We develop the theory of Brillouin light scattering (BLS) from spin wave\nmodes in ferromagnetic nanospheres, within a framework that incorporates the\nspatial variation of the optical fields within the sphere. Our recent theory of\nexchange dipole spin wave modes of the sphere provides us with eigenvectors.\nWhen properly normalized, these eigenvectors allow calculation of the absolute\ncross section of various modes which contribute to BLS spectrum. We then\npresent explicit calculation of the BLS spectrum associated with the first few\ndipole/exchange spin wave modes with emphasis on their relative intensity.",
        "positive": "Density-functional theory study of the catalytic oxidation of CO over\n  transition metal surfaces: In recent years due to improvements in calculation methods and increased\ncomputer power, it has become possible to perform first-principles\ninvestigations for ``simple'' chemical reactions at surfaces. We have carried\nout such studies for the catalytic oxidation of CO at transition metal\nsurfaces, in particular, at the ruthenium surface for which unusual behavior\ncompared to other transition metal catalysts has been reported. High gas\npressure catalytic reactor experiments have revealed that the reaction rate\nover Ru for oxidizing conditions is the highest of the transition metals\nconsidered -- in contrast, under ultra high vacuum conditions, the rate is by\nfar the lowest. We find that important for understanding the pressure\ndependence of the reaction is the fact that Ru(0001) can support high\nconcentrations of oxygen at the surface. Under these conditions, the O-metal\nbond is atypically weak compared to that at lower coverages. We have\ninvestigated a number of possible reaction pathways for CO oxidation for the\nconditions of high oxygen coverages, including scattering reactions of\ngas-phase CO at the oxygen covered surface (Eley-Rideal mechanism) as well as\nthe Langmuir-Hinshelwood mechanism involving reaction between adsorbed CO\nmolecules and O atoms."
    },
    {
        "anchor": "Non-reciprocal coherent all-optical switching between magnetic\n  multi-states: We present experimental and computational findings of the laser-induced\nnon-reciprocal motion of magnetization during ultrafast photo-magnetic\nswitching in garnets. We found distinct coherent magnetization precession\ntrajectories and switching times between four magnetization states, depending\non both directions of the light linear polarization and initial magnetic state.\nAs a fingerprint of the topological symmetry, the choice of the switching\ntrajectory is governed by an interplay of the photo-magnetic torque and\nmagnetic anisotropy. Our results open a plethora of possibilities for designing\nenergy-efficient magnetization switching routes at arbitrary energy landscapes.",
        "positive": "On the structure of SbTeI: Antimony telluroiodide (SbTeI) is predicted to be a promising material in\nmany technological applications based on theoretical simulations, however the\nbulk structure solution remains elusive. We consolidate SbTeI belonging to the\nbase-centered monoclinic lattice with a space group C 2/m by combining single\ncrystal X-ray diffraction and X-ray photoemission spectroscopy techniques. The\natomic arrangement of the reported crystal structure is remarkable with\none-dimensional double-chains forming two-dimensional blocks. In this\nstructure, the Sb$^{3+}$ ion is surrounded by Te$^{2-}$ and I$^-$, which is\ndistinguishable by an incomplete polyhedron resulting in the 5s$^2$ (Sb) lone\npair electrons in the valence band. Manipulation of this material with pressure\nto induce novel structures and properties is highly anticipated."
    },
    {
        "anchor": "Quantum oscillations of magnetization in the tight-binding electrons on\n  honeycomb lattice: We show that the new quantum oscillations of the magnetization can occur when\nthe Fermi surface consists of points (massless Dirac points) or even when the\nchemical potential is in a energy gap by studying the tight-binding electrons\non a honeycomb lattice in a uniform magnetic field. The quantum oscillations of\nthe magnetization as a function of the inverse magnetic field are known as the\nde Haas-van Alphen (dHvA) oscillations and the frequency is proportional to the\narea of the Fermi surface. The dominant period of the new oscillations\ncorresponds to the area of the first Brillouin zone and its phase is zero. The\norigin of the new quantum oscillations is the characteristic magnetic field\ndependence of the energy known as the Hofstadter butterfly and the Harper\nbroadening of Landau levels. The new oscillations are not caused by the\ncrossing of the chemical potential and Landau levels, which is the case in the\ndHvA oscillations. The new oscillations can be observed experimentally in\nsystems with large supercell such as graphene antidot lattice or ultra cold\natoms in optical lattice at an external magnetic field of a few Tesla when the\narea of the supercell is ten thousand times larger than that of graphene.",
        "positive": "Geometric control of failure behavior in perforated sheets: Adding perforations to a continuum sheet allows new modes of deformation, and\nthus modifies its elastic behavior. The failure behavior of such a perforated\nsheet is explored, using a model experimental system: a material containing a\none-dimensional array of rectangular holes. In this model system, a transition\nin failure mode occurs as the spacing and aspect ratio of the holes are varied:\nrapid failure via a running crack is completely replaced by quasi-static\nfailure which proceeds via the breaking of struts at random positions in the\narray of holes. I demonstrate that this transition can be connected to the loss\nof stress enhancement which occurs as the material geometry is modified."
    },
    {
        "anchor": "Poisson's ratio in cubic materials: Expressions are given for the maximum and minimum values of Poisson's ratio\n$\\nu$ for materials with cubic symmetry. Values less than -1 occur if and only\nif the maximum shear modulus is associated with the cube axis and is at least\n25 times the value of the minimum shear modulus. Large values of $|\\nu|$ occur\nin directions at which the Young's modulus is approximately equal to one half\nof its 111 value. Such directions, by their nature, are very close to 111.\nApplication to data for cubic crystals indicates that certain Indium Thallium\nalloys simultaneously exhibit Poisson's ratio less than -1 and greater than +2.",
        "positive": "Controlling electronic, magnetic, thermal, and optical properties of\n  boron-nitrogen codoped strontium oxide monolayer: Activation of optical\n  transitions in the VL region: The electronic, thermal, magnetic and optical properties of BN-codoped\nstrontium oxide (SrO) monolayers are studied taking into account the\ninteraction effects between the B and the N dopant atoms. The indirect band gap\nof a pure two dimensional SrO is modified to a narrow direct band gap by tuning\nthe B-N attractive interaction. The B or N separately doped SrO leads to a\nmetallic behavior, while a BN-codoped SrO has a semiconductor character. The\nstrong B-N attractive interaction changes a non-magnetic SrO to a magnetic\nsystem and reduces its heat capacity. An ab initio molecular dynamics, AIMD,\ncalculations are also utilized to check the thermodynamic stability of the pure\nand BN-codoped SrO monolayers. The band gap reduction of SrO increases the\noptical conductivity shifting the most intense peak from the Deep-UV to the\nvisible light region. The red shifted optical conductivity emerges due to the\nB-N attractive interaction. In addition, both iso- and anisotropic characters\nare seen in the optical properties depending on the strength of the B-N\nattractive interaction. It can thus be confirmed that the interaction effects\nof the BN-codopants can be used to control the properties of SrO monolayers for\nthermo- and opto-electronic devices."
    },
    {
        "anchor": "Effect of orientation and mode of loading on deformation behaviour of Cu\n  nanowires: Molecular dynamics simulations have been performed to understand the\nvariations in deformation mechanisms of Cu nanowires as a function of\norientation and loading mode (tension or compression). Cu nanowires of\ndifferent crystallographic orientations distributed uniformly on the standard\nstereographic triangle have been considered under tensile and compressive\nloading. The simulation results indicate that under compressive loading, the\norientations close to $<$100$>$ corner deform by twinning mechanism, while the\nremaining orientations deform by dislocation slip. On the other hand, all the\nnanowires deform by twinning mechanism under tensile loading. Further, the\norientations close to $<$110$>$ and $<$111$>$ corner exhibit\ntension-compression asymmetry in deformation mechanisms. In addition to\ndeformation mechanisms, Cu nanowires also display tension-compression asymmetry\nin yield stress. The orientations close to $<$001$>$ corner exhibits higher\nyield stress in tension than in compression, while the opposite behaviour\n(higher yield stress in compression than in tension) has been observed in\norientations close to $<$110$>$ and $<$111$>$ corners. For the specific\norientation of $<$102$>$, the yield stress asymmetry has not been observed. The\ntension-compression asymmetry in deformation mechanisms has been explained\nbased on the parameter $\\alpha_M$, defined as the ratio of Schmid factors for\nleading and trailing partial dislocations. Similarly, the asymmetry in yield\nstress values has been attributed to the different Schmid factor values for\nleading partial dislocations under tensile and compressive loading.",
        "positive": "Hydrogen Diffusion and Trapping in \u03b1-Iron: The Role of Quantum\n  and Anharmonic Fluctuations: We investigate the thermodynamics and kinetics of a hydrogen interstitial in\nmagnetic {\\alpha}-iron, taking account of the quantum fluctuations of the\nproton as well as the anharmonicities of lattice vibrations and hydrogen\nhopping. We show that the diffusivity of hydrogen in the lattice of BCC iron\ndeviates strongly from an Arrhenius behavior at and below room temperature. We\ncompare a quantum transition state theory to explicit ring polymer molecular\ndynamics in the calculation of diffusivity and we find that the role of phonons\nis to inhibit, not to enhance, diffusivity at intermediate temperatures in\nconstrast to the usual polaron picture of hopping. We then address the trapping\nof hydrogen by a vacancy as a prototype lattice defect. By a sequence of steps\nin a thought experiment, each involving a thermodynamic integration, we are\nable to separate out the binding free energy of a proton to a defect into\nharmonic and anharmonic, and classical and quantum contributions. We find that\nabout 30% of a typical binding free energy of hydrogen to a lattice defect in\niron is accounted for by finite temperature effects and about half of these\narise from quantum proton fluctuations. This has huge implications for the\ncomparison between thermal desorption and permeation experiments and standard\nelectronic structure theory. The implications are even greater for the\ninterpretation of muon spin resonance experiments."
    },
    {
        "anchor": "Controllable spin splitting in 2D Ferroelectric few-layer\n  ${$\u03b3}$-GeSe: ${\\gamma}$-GeSe is a new type of layered bulk material that was recently\nsuccessfully synthesized. By means of density functional theory\nfirst-principles calculations, we systematically studied the physical\nproperties of two-dimensional (2D) few-layer ${\\gamma}$-GeSe. It is found that\nfew-layer ${\\gamma}$-GeSe are semiconductors with band gaps decreasing with\nincreasing layer number; and 2D ${\\gamma}$-GeSe with layer number $n \\geq 2$\nare ferroelectric with rather low transition barriers, consistent with the\nsliding ferroelectric mechanism. Particularly, spin-orbit coupling induced spin\nsplitting is observed at the top of the valence band, which can be switched by\nthe ferroelectric reversal; furthermore, their negative piezoelectricity also\nenables the regulation of spin splitting by strain. Finally, excellent optical\nabsorption was also revealed. These intriguing properties make 2D few-layer\n${\\gamma}$-GeSe promising in spintronic and optoelectric applications.",
        "positive": "Left-Handed Surface Waves in a Photonic Structure: It is demonstrated that an isotropic left-handed medium can be constructed as\na photonic structure consisting of two dielectric materials, one with positive\nand another with negative dielectric permittivities epsilon. Electromagnetic\nwaves supported by this structure are the surface waves localized at the\ndielectric interfaces. These surface waves can be either surface phonons or\nsurface plasmons. Two examples of negative epsilon materials are used: silicon\ncarbide and free-electron gas."
    },
    {
        "anchor": "Neural network based path collective variables for enhanced sampling of\n  phase transformations: We propose a rigorous construction of a 1D path collective variable to sample\nstructural phase transformations in condensed matter. The path collective\nvariable is defined in a space spanned by global collective variables that\nserve as classifiers derived from local structural units. A reliable\nidentification of local structural environments is achieved by employing a\nneural network based classification. The 1D path collective variable is\nsubsequently used together with enhanced sampling techniques to explore the\ncomplex migration of a phase boundary during a solid-solid phase transformation\nin molybdenum.",
        "positive": "First-principles study of LiNbxM1-x O3, M= V, W, Ta, Mo for holographic\n  memory applications: For holographic memory applications, the photorefraction of well-known\nferroelectric such as lithium niobate doped with different transition metals is\nvery important. First principles study assumes special significance in this\ncontext, as to why certain transition metal atoms are better than the other. In\nthis work, Nb atom in LiNbO3 was substituted with transition elements having\nvalency greater than/equal to +5 for UV photorefraction applications, and\natomistic first-principles calculations were done using HSE06 functionals. The\nd-states of the transitional elements were found to decrease the band-gap of\nthe host material having implications for a suitable material design. Minimum\nband-gap was obtained for W, while Ta showed a maximum value. Absorption\ncoefficients were estimated for each material and based on their low values at\n351 nm (i.e. for holographic applications) that is the usual UV photorefraction\nwavelength, the elements found suitable were V, W, Ta, Mo. Then birefringence\nproperties for these crystals were also studied to predict that V and W were\ngood candidates."
    },
    {
        "anchor": "Silver paint as a soldering agent for DyBaCuO single-domains welding: Silver paint has been tested as a soldering agent for DyBaCuO single-domain\nwelding. Junctions have been manufactured on Dy-Ba-Cu-O single-domains cut\neither along planes parallel to the c-axis or along the ab-planes.\nMicrostructural and superconducting characterisations of the samples have been\nperformed. For both types of junctions, the microstructure in the joined area\nis very clean: no secondary phase or Ag particles segregation has been\nobserved. Electrical and magnetic measurements for all configurations of\ninterest are reported $\\rho(T)$ curves, and Hall probe mapping). The narrow\nresistive superconducting transition reported for all configurations shows that\nthe artificial junction does not affect significantly the measured\nsuperconducting properties of the material.",
        "positive": "Bio-Inspired Aggregation Control of Carbon Nanotubes for Ultra-Strong\n  Composites: High performance nanocomposites require well dispersion and high alignment of\nthe nanometer-sized components, at a high mass or volume fraction as well.\nHowever, the road towards such composite structure is severely hindered due to\nthe easy aggregation of these nanometer-sized components. Here we demonstrate a\nbig step to approach the ideal composite structure for carbon nanotube (CNT)\nwhere all the CNTs were highly packed, aligned, and unaggregated, with the\nimpregnated polymers acting as interfacial adhesions and mortars to build up\nthe composite structure. The strategy was based on a bio-inspired aggregation\ncontrol to limit the CNT aggregation to be sub 20--50 nm, a dimension\ndetermined by the CNT growth. After being stretched with full structural\nrelaxation in a multi-step way, the CNT/polymer (bismaleimide) composite\nyielded super-high tensile strengths up to 6.27--6.94 GPa, more than 100%\nhigher than those of carbon fiber/epoxy composites, and toughnesses up to\n117--192 MPa. We anticipate that the present study can be generalized for\ndeveloping multifunctional and smart nanocomposites where all the surfaces of\nnanometer-sized components can take part in shear transfer of mechanical,\nthermal, and electrical signals."
    },
    {
        "anchor": "Realization of Stable Ferromagnetic Order in Topological Insulator:\n  Codoping Enhanced Magnetism in 4f Transition Metal Doped Bi2Se3: The realization of long range and insulating ferromagnetic states in\ntopological insulator (TI) has been a pressing issue since its discovery. Only\nrecently, such state was achieved in Cr-doped Bi2-xSbxTe3, leading to the\ndiscovery of quantum anomalous Hall effect (QAHE). However, the effect is only\nobserved at extremely low temperatures mainly due to the limited magnetism. To\nfully understand the mechanism of the ferromagnetic ordering whereby improving\nthe ferromagnetism, we investigated 4f transition metal-doped Bi2Se3, using\ndensity-functional-theory approaches. We found that Eu and Sm prefer the Bi\nsubstitutional sites with large magnetic moments to ensure stable long-range\nferromagnetic states. Additionally, codoping can be a novel strategy to\npreserve the insulating property of the host material as well as improving the\nincorporation of magnetic dopants. Our findings thus offer the critical step in\nfacilitating the realization of QAHE in TI systems.",
        "positive": "Manipulation and detection of spin state of Iron-Porphyrin by dedicated\n  chemisorption on magnetic substrates: One of the key factors behind the rapid evolution of molecular spintronics is\nthe efficient realization of spin manipulation of organic molecules with a\nmagnetic center. The spin state of such molecules may depend crucially on the\ninteraction with the substrate on which they are adsorbed. In this letter, we\ndemonstrate, using ab initio density functional calculations, that the\nstabilization of a high spin state of an iron porphyrin (FeP) molecule can be\nachieved via a dedicated chemisorption on magnetic substrates of different\nspecies and orientations. It is shown that the strong covalent interaction with\nthe substrate increases Fe-N bond lengths in FeP and hence a switching to a\nhigh spin state (S=2) from a low spin state (S=1) is achieved. A ferromagnetic\nexchange interaction is established through a direct exchange between Fe and\nsubstrate magnetic atoms as well as through an indirect exchange via the N\natoms in FeP. The mechanism of exchange interaction is further analyzed by\nconsidering structural models constructed from ab initio calculations. Finally,\nwe illustrate the possibility of detecting a change in the molecular spin state\nby x-ray magnetic circular dichroism, Raman spectroscopy and spin-polarized\nscanning tunneling microscopy."
    },
    {
        "anchor": "Spin-Splitting and Rashba-Effect at Mono-Layer GaTe in the Presence of\n  Strain: In this paper, spintronic properties of the mono-layer GaTe under biaxial and\nuniaxial strain is investigated. Here, spin properties of two structures of\nGaTe, one with mirror symmetry and the other with inversion symmetry, is\nstudied. We have also calculated the band structure of GaTe with and without\nspin-orbit coupling to find out the importance of spinorbit interaction (SOI)\non its band structure. We find band gap can be modified by applying spin-orbit\ncoupling in the presence of strain. We explore Mexican-hat dispersion for\ndifferent structures and different strain. We find Mexican-hat can be tuned\nhowever some cases shows any Mexican-hat. We calculate spin-splitting in\nconduction and valence band in the presence of strain where the structure with\ninversion symmetry doesn't show any splitting. We find in some cases, GaTe\nindicates Rashba dispersion that can be adjusted by strain. The amount of\nRashba parameters may be in the order of other reported two-dimensional\nmaterials.",
        "positive": "On the evaluation of spinnability of metallic materials in the powerful\n  spinning process: a review: Currently, the rapidly developing powerful spinning processes of metals are\nwidely used in many industrial sectors including those requiring high precision\nprocessing of metal materials, and the types and production of spun part are\nincreasing. Evaluating the spinnability (flow formability) of material is very\nimportant for expanding the application of flow-forming process for producing a\nlot of products. The spinnability of metal is an important basic data that\npredicts defects that may appear in the processing of products in advance,\nmakes it possible to create rational processes, and guarantees product quality.\nIn this paper, we comprehensively analyze the data studied so far on the\nspinnability evaluation during powerful spinning conducted at room temperature,\nit was described with respect to the test methods and the theoretical methods\nfor evaluating spinnability of metallic materials, and the effect of various\nfactors on the spinnability."
    },
    {
        "anchor": "Magnetoconductance modulations due to interlayer tunneling in radial\n  superlattices: Radial superlattices are nanostructured materials obtained by rolling-up thin\nsolid films into spiral-like tubular structures. The formation of these\n\"high-order\" superlattices from two-dimensional crystals or ultrathin films is\nexpected to result in a transition of transport characteristics from\ntwo-dimensional to one-dimensional. Here, we show that a transport hallmark of\nradial superlattices is the appearance of magnetoconductance modulations in the\npresence of externally applied axial magnetic fields. This phenomenon\ncritically relies on electronic interlayer tunneling processes that activates\nan unconventional Aharonov-Bohm-like effect. Using a combination of density\nfunctional theory calculations and low-energy continuum models, we determine\nthe electronic states of a paradigmatic single-material radial superlattice --\na two-winding carbon nanoscroll -- and indeed show momentum-dependent\noscillations of the magnetic states in axial configuration, which we\ndemonstrate to be entirely due to hopping between the two windings of the\nspiral-shaped scroll.",
        "positive": "A Structural Model for Octagonal Quasicrystals Derived from Octagonal\n  Symmetry Elements Arising in $\u03b2$-Mn Crystallization of a Simple Monatomic\n  Liquid: While performing molecular dynamics simulations of a simple monatomic liquid,\nwe observed the crystallization of a material displaying octagonal symmetry in\nits simulated diffraction pattern. Inspection of the atomic arrangements in the\ncrystallization product reveals large grains of the beta-Mn structure aligned\nalong a common 4-fold axis, with 45 degree rotations between neighboring\ngrains. These 45 degree rotations can be traced to the intercession of a second\ncrystalline structure fused epitaxially to the beta-Mn domain surfaces, whose\nprimitive cell has lattice parameters a = b = c = a_{beta-Mn}, alpha = beta =\n90 degrees, and gamma = 45 degrees. This secondary phase adopts a structure\nwhich appears to have no known counterpart in the experimental literature, but\ncan be simply derived from the Cr_3Si and Al_3Zr_4 structure types. We used\nthese observations as the basis for an atomistic structural model for octagonal\nquasicrystals, in which the beta-Mn and the secondary phase structure unit\ncells serve as square and rhombic tiles (in projection), respectively. Its\ndiffraction pattern down the octagonal axis resembles those experimentally\nmeasured. The model is unique in being consistent with high-resolution electron\nmicroscopy images showing square and rhombic units with edge-lengths equal to\nthat of the beta-Mn unit cell. Energy minimization of this configuration, using\nthe same pair potential as above, results in an alternative octagonal\nquasiperiodic structure with the same tiling but a different atomic decoration\nand diffraction pattern."
    },
    {
        "anchor": "Switchable ErSc2N rotor within a C80 fullerene cage: An EPR and\n  photoluminescence excitation study: Systems exhibiting both spin and orbital degrees of freedom, of which Er3+ is\none, can offer mechanisms for manipulating and measuring spin states via\noptical excitations. Motivated by the possibility of observing\nphotoluminescence and electron paramagnetic resonance from the same species\nlocated within a fullerene molecule, we initiated an EPR study of Er3+ in\nErSc2N@C80. Two orientations of the ErSc2N rotor within the C80 fullerene are\nobserved in EPR, consistent with earlier studies using photoluminescence\nexcitation (PLE) spectroscopy. For some crystal field orientations, electron\nspin relaxation is driven by an Orbach process via the first excited electronic\nstate of the 4I_15/2 multiplet. We observe a change in the relative populations\nof the two ErSc2N configurations upon the application of 532 nm illuminations,\nand are thus able to switch the majority cage symmetry. This\nphotoisomerisation, observable by both EPR and PLE, is metastable, lasting many\nhours at 20 K.",
        "positive": "Sliding-mediated ferroelectric phase transition in CuInP2S6 under\n  pressure: Interlayer stacking order has recently emerged as a unique degree of freedom\nto control crystal symmetry and physical properties in two-dimensional van der\nWaals (vdW) materials and heterostructures. By tuning the layer stacking\npattern, symmetry-breaking and electric polarization can be created in\notherwise non-polar crystals, whose polarization reversal depends on the\ninterlayer sliding motion. Herein, we demonstrate that in a vdW layered\nferroelectric, its existing polarization is closely coupled to the interlayer\nsliding driven by hydrostatic pressure. Through combined structural,\nelectrical, vibrational characterizations, and theoretical calculations, we\nclearly map out the structural evolution of CuInP2S6 under pressure. A tendency\ntowards a high polarization state is observed in the low-pressure region,\nfollowed by an interlayer-sliding-mediated phase transition from a monoclinic\nto a trigonal phase. Along the transformation pathway, the displacive-instable\nCu ion serves as a pivot point that regulates the interlayer interaction in\nresponse to external pressure. The rich phase diagram of CuInP2S6, which is\nenabled by stacking orders, sheds light on the physics of vdW ferroelectricity\nand opens an alternative route to tailoring long-range order in vdW layered\ncrystals."
    },
    {
        "anchor": "Anisotropic Thermal Transport in Phase-Transition Layered 2D Alloys\n  WSe2(1-x)Te2x: Transition metal dichalcogenide (TMD) alloys have attracted great interests\nin recent years due to their tunable electronic properties, especially the\nsemiconductor-metal phase transition, along with their potential applications\nin solid-state memories and thermoelectrics. However, the thermal conductivity\nof layered two-dimensional (2D) TMD alloys remains largely unexplored despite\nthat it plays a critical role in the reliability and functionality of\nTMD-enabled devices. In this work, we study the temperature-dependent\nanisotropic thermal conductivity of the phase-transition 2D TMD alloys\nWSe2(1-x)Te2x in both the in-plane direction (parallel to the basal planes) and\nthe cross-plane direction (along the c-axis) using time-domain\nthermoreflectance measurements. In the WSe2(1-x)Te2x alloys, the cross-plane\nthermal conductivity is observed to be dependent on the heating frequency\n(modulation frequency of the pump laser) due to the non-equilibrium transport\nbetween different phonon modes. Using a two-channel heat conduction model, we\nextracted the anisotropic thermal conductivity at the equilibrium limit. A\nclear discontinuity in both the cross-plane and the in-plane thermal\nconductivity is observed as x increases from 0.4 to 0.6 due to the phase\ntransition from the 2H to Td phase in the layered 2D alloys. The temperature\ndependence of thermal conductivity for the TMD alloys was found to become\nweaker compared with the pristine 2H WSe2 and Td WTe2 due to the atomic\ndisorder. This work serves as an important starting point for exploring phonon\ntransport in layered 2D alloys.",
        "positive": "Testing the influence of the temperature, RH and filler type and content\n  on the Universal Power Law for new reduced graphene oxide TPU composites: In this paper, 6 different reduced graphene oxide (rGO) were prepared by a\nmodified Hummers method and reduced by thermochemical methods. rGO materials\nwere intentionally prepared to obtain different BET and thickness and oxygen\ncontent maintaining constant the lateral size to compare its performance on\nthermoplastic polyurethane (TPU) matrix. Microstructure and the effect of the\nincorporation of rGO on the hardness and electrical properties of TPU were\ninvestigated. It has been studied the temperature and humidity dependence of\nthe electrical conductivity and the sensitivity and the response time to\nhumidity changes have been determined. Influence of the filler content,\ntemperature and humidity on the Jonschers universal power law (UPL) for ac\nconductivity vs frequency and its fitting parameters A and n were determined.\nIt has been observed an anomalous behaviour (according to UPL) and a linear\ncorrelation between log A and n independently of the filler content, humidity\nand temperature, however there is an influence of the rGO used for the\npreparation of the composite. To study the transport mechanisms the\nexperimental results were adjusted to the equation and the maximum adjustment\nfor like other carbon nanocomposites however there is not an unequivocal\nbehaviour."
    },
    {
        "anchor": "Modeling of Nucleation Processes: Nucleation is the onset of a first-order phase transition by which a\nmetastable phase transforms into a more stable one. Such a phase transition\noccurs when an initial system initially in equilibrium is destabilized by the\nchange of an external parameter like the temperature or the pressure. If the\nperturbation is small enough, the system does not become unstable but rather\nstays metastable. In diffusive transformations, the system then evolves through\nthe nucleation, the growth and the coarsening of a second phase. Such a phase\ntransformation is found in a lot of situations in materials science like\ncondensation of liquid droplets from a supersaturated vapor, solidification,\nprecipitation from a supersaturated solid solution, ... The initial stage of\nall these different processes can be well described within the same framework.\nSince its initial formulation in 1927 by Volmer, Weber and Farkas and its\nmodification in 1935 by Becker and D\\\"oring the classical nucleation theory has\nbeen a suitable tool to model the nucleation stage in phase transformations. In\nthis article, we first describe this theory. A kinetic approach, the cluster\ndynamics, can also be used to describe nucleation. This constitutes the second\npart of this article. The links as well as the difference between both\ndescriptions are emphasized. Since its initial formulation, the classical\nnucleation theory has been enriched, so as to take into account the fact that\nclusters other than monomers can migrate and react. It has been also extended\nto multi-component systems. These generalizations of the initial formalism are\nalso presented.",
        "positive": "Uncompensated Polarization in Incommensurate Modulations of Perovskite\n  Antiferroelectrics: Complex polar structures of incommensurate modulations (ICMs) are revealed in\nchemically modified PbZrO$_3$ perovskite antiferroelectrics using advanced\ntransmission electron microscopy techniques. The Pb-cation displacements,\npreviously assumed to arrange in a fully-compensated antiparallel fashion, are\nfound to be either antiparallel but with different magnitudes, or in a nearly\northogonal arrangement in adjacent stripes in the ICMs. Ab initio calculations\ncorroborate the low-energy state of these arrangements. Our discovery corrects\nthe atomic understanding of ICMs in PbZrO$_3$-based perovskite\nantiferroelectrics."
    },
    {
        "anchor": "In-situ MOCVD Growth and Band Offsets of Al$_2$O$_3$ Dielectric on\n  $\u03b2$-Ga$_2$O$_3$ and $\u03b2$-(Al$_x$Ga$_{1-x}$)$_2$O$_3$ thin films: The in-situ metalorganic chemical vapor deposition (MOCVD) growth of\nAl$_2$O$_3$ dielectrics on $\\beta$-Ga$_2$O$_3$ and\n$\\beta$-(Al$_x$Ga$_{1-x}$)$_2$O$_3$ films is investigated as a function of\ncrystal orientations and Al compositions of $\\beta$-(Al$_x$Ga$_{1-x}$)$_2$O$_3$\nfilms. The interface and film qualities of Al$_2$O$_3$ dielectrics are\nevaluated by high resolution X-ray diffraction (HR-XRD) and scanning\ntransmission electron microscopy (HR-STEM) imaging, which indicate the growth\nof high quality amorphous Al$_2$O$_3$ dielectrics with abrupt interfaces on\n(010), (100) and (-201) oriented $\\beta$-(Al$_x$Ga$_{1-x}$)$_2$O$_3$ films. The\nsurface stoichiometries of Al$_2$O$_3$ deposited on all orientations of\n$\\beta$-(Al$_x$Ga$_{1-x}$)$_2$O$_3$ are found to be well maintained with a\nbandgap energy of 6.91 eV as evaluated by high resolution x-ray photoelectron\nspectroscopy, which is consistent with the atomic layer deposited (ALD)\nAl$_2$O$_3$ dielectrics. The evolution of band offsets at both in-situ MOCVD\nand ex-situ ALD deposited Al$_2$O$_3$/$\\beta$-(Al$_x$Ga$_{1-x}$)$_2$O$_3$ are\ndetermined as a function of Al composition, indicating the influence of the\ndeposition method, orientation, and Al composition of\n$\\beta$-(Al$_x$Ga$_{1-x}$)$_2$O$_3$ films on resulting band alignments. Type II\nband alignments are determined at the MOCVD grown\nAl$_2$O$_3$/$\\beta$-(Al$_x$Ga$_{1-x}$)$_2$O$_3$ interfaces for (010) and (100)\norientations, whereas type I band alignments with relatively lower conduction\nband offsets are observed along (-201) orientation. Results from this work\nrevealed that the in-situ MOCVD deposited high quality Al$_2$O$_3$ dielectrics\nwith sharp interfaces can be considered as a viable alternative of commonly\nused ex-situ deposited (ALD) Al$_2$O$_3$ for developing high performance\n$\\beta$-Ga$_2$O$_3$ and $\\beta$-(Al$_x$Ga$_{1-x}$)$_2$O$_3$ based devices.",
        "positive": "Effect of Electrical Properties on Gd modified BiFeO3-PbZrO3: The 0.5(BiGdxFe1-xO3)-0.5(PbZrO3) composite was synthesized using a high\ntemperature solid-state reaction technique. Preliminary X-ray structural\nanalysis confirms the formation of the composite. The dielectric constant and\nloss tangent have been studied. The hysteresis loop suggest that the material\nis lossy. The impedance parameters were studied using an impedance analyzer in\na wide range of frequency (102-106 Hz) at different temperatures for all\nsamples. The Nyquist plot suggests the contribution of bulk effect as well as\ngrain boundary effect and the bulk resistance deceases with rise in temperature\nfor all samples. The electrical transport confirms the presence of hopping\nmechanism in the material. The dc conductivity increases with rise in\ntemperature. The frequency variation of ac conductivity shows that the compound\nobeys Jonschers universal power law and confirms the Small Polaron (SP)\ntunneling effect due to low activation energy for all samples. Temperature\ndependence of dc and ac conductivity indicates that electrical conduction in\nthe materials are thermally activated process."
    },
    {
        "anchor": "CNT effective interfacial energy and pre-exponential kinetic factor from\n  measured NaCl crystal nucleation time distributions in contracting\n  microdroplets: Nucleation, the birth of a stable cluster from disorder, is inherently\nstochastic. Yet up to date, there are no quantitative studies on NaCl\nnucleation that accounts for its stochastic nature. Here, we report the first\nstochastic treatment of NaCl-water nucleation kinetics. Using a recently\ndeveloped microfluidic system and evaporation model, our measured interfacial\nenergies extracted from a modified Poisson distribution of nucleation time show\nan excellent agreement with theoretical predictions. Furthermore, analysis of\nnucleation parameters in 0.5 pL, 1.5pL and 5.5 pL microdroplets reveals an\ninteresting interplay between kinetic confinement and shifting of nucleation\nmechanisms. Overall, our findings highlight the need to treat nucleation\nstochastically rather deterministically to bridge the gap between theory and\nexperiment.",
        "positive": "Stark Effect of Doped Two-Dimensional Transition Metal Dichalcogenides: The band gap of two-dimensional (2D) semiconductors can be efficiently tuned\nby gate electric field, which is so called the Stark effect. We report that\ndoping, which is essential in realistic devices, will substantially change the\nStark effect of few-layer transition metal dichalcogenides in unexpected ways.\nParticularly in bilayer structures, because of the competition between strong\nquantum confinement and intrinsic screening length, electron and hole dopings\nexhibit surprisingly different Stark effects: doped electrons actively screen\nthe external field and result in a nonlinear Stark effect; however, doped holes\ndo not effectively screen the external field, causing a linear Stark effect\nthat is the same as that of undoped materials. Our further analysis shows that\nthis unusual doping effect is not limited within transition metal\ndichalcogenides but general for 2D structures. Therefore, doping plays a much\nmore crucial role in functional 2D devices and this unusual Stark effect also\nprovides a new degree of freedom to tune band gaps and optical properties of 2D\nmaterials."
    },
    {
        "anchor": "Growth and characterization of thin epitaxial Co3O4(111) films: The growth and characterization of epitaxial Co3O4(111) films grown by oxygen\nplasma-assisted molecular beam epitaxy on single crystalline a-Al2O3(0001) is\nreported. The Co3O4(111) grows single crystalline with the epitaxial relation\nCo3O4(111)[-12-1]||a-Al2O3(0001)[10-10], as determined from in situ electron\ndiffraction. Film stoichiometry is confirmed by x-ray photoelectron\nspectroscopy, while ex situ x-ray diffraction measurements show that the Co3O4\nfilms are fully relaxed. Post-growth annealing induces significant\nmodifications in the film morphology, including a sharper Co3O4/a-Al2O3\ninterface and improved surface crystallinity, as shown by x-ray reflectometry,\natomic force microscopy and electron diffraction measurements. Despite being\npolar, the surface of both as-grown and annealed Co3O4(111) films are (1 * 1),\nwhich can be explained in terms of inversion in the surface spinel structure.",
        "positive": "The role of hydrostatic stress in determining the bandgap of InN\n  epilayers: We establish a correlation between the internal stress in InN epilayers and\ntheir optical properties such as the measured absorption band edge and\nphotoluminescence emission wavelength. By a careful evaluation of the lattice\nconstants of InN epilayers grown on c-plane sapphire substrates under various\nconditions by metalorganic vapor phase epitaxy we find that the films are under\nprimarily hydrostatic stress. This results in a shift in the band edge to\nhigher energy. The effect is significant, and may be responsible for some of\nthe variations in InN bandgap reported in the literature."
    },
    {
        "anchor": "Beyond ab initio reaction simulator: an application to GaN metalorganic\n  vapor phase epitaxy: To develop a quantitative reaction simulator, data assimilation was performed\nusing high-resolution time-of-flight mass spectrometry (TOF-MS) data applied to\nGaN metalorganic vapor phase epitaxy system. Incorporating ab initio knowledge\ninto the optimization successfully reproduces not only the concentration of\nCH$_4$ (an impurity precursor) as an objective variable but also known reaction\npathways. The simulation results show significant production of GaH$_3$, a\nprecursor of GaN, which has been difficult to detect in TOF-MS experiments. Our\nproposed approach is expected to be applicable to other applied physics fields\nthat require quantitative prediction that goes beyond ab initio reaction rates.",
        "positive": "NIMS-OS: An automation software to implement a closed loop between\n  artificial intelligence and robotic experiments in materials science: NIMS-OS (NIMS Orchestration System) is a Python library created to realize a\nclosed loop of robotic experiments and artificial intelligence (AI) without\nhuman intervention for automated materials exploration. It uses various\ncombinations of modules to operate autonomously. Each module acts as an AI for\nmaterials exploration or a controller for a robotic experiments. As AI\ntechniques, Bayesian optimization (PHYSBO), boundless objective-free\nexploration (BLOX), phase diagram construction (PDC), and random exploration\n(RE) methods can be used. Moreover, a system called NIMS automated robotic\nelectrochemical experiments (NAREE) is available as a set of robotic\nexperimental equipment. Visualization tools for the results are also included,\nwhich allows users to check the optimization results in real time. Newly\ncreated modules for AI and robotic experiments can be added easily to extend\nthe functionality of the system. In addition, we developed a GUI application to\ncontrol NIMS-OS.To demonstrate the operation of NIMS-OS, we consider an\nautomated exploration for new electrolytes. NIMS-OS is available at\nhttps://github.com/nimsos-dev/nimsos."
    },
    {
        "anchor": "Ab initio study of mirages and magnetic interactions in quantum corrals: The state of the art ab initio calculations of quantum mirages,the\nspin-polarization of surface-state electrons and the exchange interaction\nbetween magnetic adatoms in Cu and Co corrals on Cu(111) are presented. We find\nthat the spin-polarization of the surface-state electrons caused by magnetic\nadatoms can be projected to a remote location and can be strongly enhanced in\ncorrals compared to an open surface.Our studies give a clear evidence that\nquantum corrals could permit to tailor the exchange interaction between\nmagnetic adatoms at large separations. The spin-polarization of surface-state\nelectrons at the empty focus in the Co corral used in the experimental setup of\nManoharan et al., (Nature 403, 512 (2000)) is revealed.",
        "positive": "Athermal Shear-Transformation-Zone Theory of Amorphous Plastic\n  Deformation I: Basic Principles: We develop an athermal version of the shear-transformation-zone (STZ) theory\nof amorphous plasticity in materials where thermal activation of irreversible\nmolecular rearrangements is negligible or nonexistent. In many respects, this\ntheory has broader applicability and yet is simpler than its thermal\npredecessors. For example, it needs no special effort to assure consistency\nwith the laws of thermodynamics, and the interpretation of yielding as an\nexchange of dynamic stability between jammed and flowing states is clearer than\nbefore. The athermal theory presented here incorporates an explicit\ndistribution of STZ transition thresholds. Although this theory contains no\nconventional thermal fluctuations, the concept of an effective temperature is\nessential for understanding how the STZ density is related to the state of\ndisorder of the system."
    },
    {
        "anchor": "Comment On \"A modified Lennard-Jones-type equation of state for solids\n  strictly satisfying the spinodal condition\": The cohesive energies of solids calculated using mGLJ EOS proposed by Sun\nJiuxun (Sun Jiuxun, J. Phys.: Condens. Matter 17, L103 (2005)) are seen to be\nerroneous. Also we observed that the thermodynamic properties calculated using\nthe mGLJ potential diverge for materials whose pressure derivative of bulk\nmodulus at equilibrium is less than 5. Thus the mGLJ potential cannot be used\nin liquid state theories and molecular simulations to obtain thermodynamic\nproperties.",
        "positive": "Diffusion-emission theory of photon enhanced thermionic emission solar\n  energy harvesters: Numerical and semi-analytical models are presented for\nphoton-enhanced-thermionic-emission (PETE) devices. The models take diffusion\nof electrons, inhomogeneous photogeneration, and bulk and surface recombination\ninto account. The efficiencies of PETE devices with silicon cathodes are\ncalculated. Our model predicts significantly different electron affinity and\ntemperature dependence for the device than the earlier model based on a\nrate-equation description of the cathode. We show that surface recombination\ncan reduce the efficiency below 10% at the cathode temperature of 800 K and the\nconcentration of 1000 suns, but operating the device at high injection levels\ncan increase the efficiency to 15%."
    },
    {
        "anchor": "Two-Dimensional Transition Metal Silicate Formed on Ru (0001) by\n  Hydrogenation: Bottom-up synthesis of two-dimensional transition-metal silicates has been\nchallenging due to strong overlayer-substrate interactions, which prevents the\nexfoliation of the overlayer. Here, using density functional theory\ncalculations, we systematically investigate the hydrogenation of the overlayer\nas a way to decrease the substrate and overlayer interactions. Using the\nFe$_2$Si$_2$O$_8\\cdot$O/Ru(0001) structure as our starting point Wlodarczyk et.\nal. [1], we study hydrogenation levels up to\nFe$_2$Si$_2$O$_9$H$_4\\cdot$/Ru(0001). Structural and thermodynamical properties\nare studied at different hydrogenation levels to show under which conditions,\nthe exfoliation can be feasible. Simulated core-level shifts show that Fe is\nprimarily in 3+ state through the hydrogenation of\nFe$_2$Si$_2$O$_8\\cdot$O/Ru(0001). Simulated reflection adsorption infrared\nspectroscopy (RAIRS) yield distinctive shifts in vibrational properties with\nincreasing hydrogenation which can guide experiments.\n  [1] R. Wlodarczyk et al., \"Atomic structure of an ultrathin Fe-silicate film\ngrown on a metal: A monolayer of clay?\", J. Am. Chem. Soc., 135, 19222, (2013).",
        "positive": "An alternative strategy for the use of a low-cost age-hardenable\n  Fe-Si-Ti steel for automotive application: For High Strength Low Alloy (HSLA) steels or for age-hardenable steels\n(maraging) the strengthening by precipitation is done before forming operation\nin order to increase the yield stress as much as possible. In this publication\nthe advantages of an hardening thermal treatment after forming operation are\ninvestigated in a low cost age-hardenable steel Fe-Si-Ti consistent with\nautomotive application."
    },
    {
        "anchor": "Beam Propagation in Photonic Crystals: The recent interest in the imaging possibilities of photonic crystals\n(superlensing, superprism, optical mirages etc...) call for a detailed analysis\nof beam propagation inside a finite periodic structure. In this paper, we give\nsuch a theoretical and numerical analysis of beam propagation in 1D and 2D\nphotonic crystals. We show that, contrarily to common knowledge, it is not\nalways true that the direction of propagation of a beam is given by the normal\nto the dispersion curve. We explain this phenomenon in terms of evanescent\nwaves and we construct a renormalized dispersion curve that gives the correct\ndirection.",
        "positive": "Acoustic-pressure-assisted engineering of aluminium foams: Foaming metals modulates their physical properties, enabling attractive\napplications where lightweight, low thermal conductivity or acoustic isolation\nare desirable. Adjusting the size of the bubbles in the foams is particularly\nrelevant for targeted applications. Here we provide a method with a detailed\ntheoretical understanding how to tune the size of the bubbles in aluminium\nmelts in-situ via acoustic pressure. Our description is in full agreement with\nthe high-rate three-dimensional X-Ray radioscopy of the bubble formation. We\ncomplement our study with the intriguing results on the effect of foaming on\nelectrical resistivity, Seebeck coefficient and thermal conductivity from\ncryogenic to room temperature. Compared to bulk materials the investigated foam\nshows an enhancement in the thermoelectric figure of merit. These results\nherald promising application of foaming in thermoelectrics materials and\ndevices for thermal energy conversion."
    },
    {
        "anchor": "The reversal of magnetization driven by the Dzyaloshinskii-Moriya\n  interaction(DMI) in perovskite Bi2FeMnO6: Ab initio calculations show that the coupling between\nantiferrodistortive(AFD) distortions and magnetization in perovskite Bi2FeMnO6\nis prohibited to make magnetization rotate as on-site Coulomb interaction($U$)\nis larger than 2.7 eV, where anomalies in antiferromagnetic(AFM) vectors and\nband gap varying with on-site Coulomb interaction can be observed. This\ncoupling is attributed to the antisymmetric Dzyaloshinskii-Moriya\ninteraction(DMI) driven by the eg-eg states AFM interaction and charge\nredistribution with respect to different AFD distortions.",
        "positive": "Transmission electron microscopy and ferromagnetic resonance\n  investigations of tunnel magnetic junctions using Co2MnGe Heusler alloy as\n  magnetic electrodes: HRTEM, nano-beam electronic diffraction, energy dispersive X-rays scanning\nspectroscopy, Vibrating Sample Magnetometry (VSM) and FerroMagnetic Resonance\n(FMR) techniques are used in view of comparing (static and dynamic) magnetic\nand structural properties of Co2MnGe (13 nm)/Al2O3 (3 nm)/Co (13 nm) tunnel\nmagnetic junctions (TMJ), deposited on various single crystalline substrates\n(a-plane sapphire, MgO(100) and Si(111)). They allow for providing a\ncorrelation between these magnetic properties and the fine structure\ninvestigated at atomic scale. The Al2O3 tunnel barrier is always amorphous and\ncontains a large concentration of Co atoms, which, however, is significantly\nreduced when using a sapphire substrate. The Co layer is polycrystalline and\nshows larger grains for films grown on a sapphire substrate. The VSM\ninvestigation reveals in-plane anisotropy only for samples grown on a sapphire\nsubstrate. The FMR spectra of the TMJs are compared to the obtained ones with a\nsingle Co and Co2MnGe films of identical thickness deposited on a sapphire\nsubstrate. As expected, two distinct modes are detected in the TMJs while only\none mode is observed in each single film. For the TMJ grown on a sapphire\nsubstrate the FMR behavior does not significantly differ from the superposition\nof the individual spectra of the single films, allowing for concluding that the\nexchange coupling between the two magnetic layers is too small to give rise to\nobservable shifts. For TMJs grown on a Si or on a MgO substrate the resonance\nspectra reveal one mode which is nearly identical to the obtained one in the\nsingle Co film, while the other observed resonance shows a considerably smaller\nintensity and cannot be described using the magnetic parameters appropriate to\nthe single Co2MnGe film."
    },
    {
        "anchor": "Symmetry of high-piezoelectric Pb-based complex perovskites at the\n  morphotropic phase boundary I. Neutron diffraction study on Pb(Zn1/3Nb2/3)O3\n  -9%PbTiO3: The symmetry was examined using neutron diffraction method on\nPb(Zn1/3Nb2/3)O3 -9%PbTiO3 (PZN/9PT) which has a composition at the\nmorphotropic phase boundary (MPB) between Pb(Zn1/3Nb2/3)O3 and PbTiO3. The\nresults were compared with those of other specimens with same composition but\nwith different prehistory. The equilibrium state of all examined specimens is\nnot the mixture of rhombohedral and tetragonal phases of the end members but\nexists in a new polarization rotation line Mc# (orthorhombic-monoclinic line).\nAmong examined specimens, one exhibited tetragonal symmetry at room temperature\nbut recovered monoclinic phase after a cooling and heating cycle.",
        "positive": "Quantum interference effects in electron transport through nitrobenzene\n  with pyridil anchor groups: We present density functional theory (DFT) based non-equilibrium Green's\nfunction (NEGF) calculations for the conductance through a nitrobenzene\nmolecule, which is anchored by pyridil-groups to Au electrodes. This work is\nbuilding up on earlier theoretical studies where quantum interference effects\n(QIE) have been identified both in qualitative tight binding and in DFT\ndescriptions for the same molecule with different chemical connections to the\nleads. The novelty in the current contribution is two-fold: i) The\npyridil-anchors guarantee for the conductance to be determined by rather narrow\npeaks situated closely to the Fermi energy which is relevant because it might\nmaximize the impact of quantum interferences on the I/V behaviour. In a scan of\neight different junction setups, where the connection sites of aromatic rings,\ntheir torsion angle with respect to each other and the surface structure have\nbeen varied, QIE was found to dominate the conductance for only one planar\ngeometry. For finite torsion angles between aromatic rings the effect moves to\nhigher energies and would therefore only be accessible for experimental\nobservation in a gated junction. ii) A detailed comparison between simple\ntopological models and DFT results for the investigated systems aims at\nassessing the usefulness of such models as analysis tools for a better\nunderstanding of the physics of QIE and its structure dependence."
    },
    {
        "anchor": "Strain engineering of ferromagnetic-graphene-ferroelectric\n  nanostructures: We calculated a spin-polarized conductance in the almost unexplored\nnanostructure \"high temperature ferromagnetic insulator/ graphene/\nferroelectric film\" with a special attention to the impact of electric\npolarization rotation in a strained multiaxial ferroelectric film. The rotation\nand value of polarization vector are controlled by a misfit strain. We proposed\na phenomenological model, which takes into account the shift of the Dirac point\ndue to the proximity of ferromagnetic insulator and uses the Landauer formula\nfor the conductivity of the graphene channel. We derived analytical\nexpressions, which show that the strain-dependent ferroelectric polarization\ngoverns the concentration of two-dimensional charge carriers and Fermi level in\ngraphene in a self-consistent way. We demonstrate the realistic opportunity to\ncontrol the spin-polarized conductance of graphene by a misfit strain (\"strain\nengineering\") at room and higher temperatures in the nanostructures\nCoFeO4/graphene/PZT and Y3Fe5O12/graphene/PZT. Obtained results open the\npossibilities for the applications of ferromagnetic/graphene/ferroelectric\nnanostructures as non-volatile spin filters and spin valves.",
        "positive": "The electrothermal conductance and heat capacity of black phosphorus: We study a thermal gradient induced current $\\left(I_{th}\\right)$ flow in\npotassium-doped two-dimensional anisotropic black phosphorus (BP) with\nsemi-Dirac dispersion. The prototype device is a BP channel clamped between two\ncontacts maintained at unequal temperatures. The choice of BP lies in the\npredicted efficient thermolectric behaviour. A temperature-induced difference\nin the Fermi levels of the two contacts drives the current (typified by the\nelectro-thermal conductance) which we calculate using the Landauer transport\nequation. The current shows an initial rise when the device is operated at\nlower temperatures. The rise stalls at progressively higher temperatures and\n$I_{th}$ acquires a plateau-like flat profile indicating a competing effect\nbetween a larger number of transmission modes and a corresponding drop in the\nFermi level difference between the contacts. The current is computed for both\n\\textit{n}- and \\textit{p}-type BP and the difference thereof is attributed to\nthe particle-hole asymmetry. The utility of such calculations lie in conversion\nof the heat production and an attendant temperature gradient in miniaturized\ndevices to useful electric power and a possible realization of solid-state\nPeltier cooling. Unlike the flow of $I_{th}$ that removes heat, the ability of\na material to maintain a steady temperature is reflected in its heat capacity\nwhich is formulated in this work for BP via a Sommerfeld expansion. In the\nconcluding part, we draw a microscopic connection between the two seemingly\ndisparate processes of heat removal and absorption by pinning down their origin\nto the underlying density of states. Finally, a qualitative analysis of a\nCarnot-like efficiency of the considered thermoelectric engine is performed\ndrawing upon the previous results on thermal current and heat capacity."
    },
    {
        "anchor": "Landau quantization in coupled Weyl points: a case study of semimetal\n  NbP: Weyl semimetal (WSM) is a newly discovered quantum phase of matter that\nexhibits topologically protected states characterized by two separated Weyl\npoints with linear dispersion in all directions. Here, via combining\ntheoretical analysis and magneto-infrared spectroscopy of an archetypal Weyl\nsemimetal, niobium phosphide, we demonstrate that the coupling between Weyl\npoints can significantly modify the electronic structure of a WSM and provide a\nnew twist to the protected states. These findings suggest that the coupled Weyl\npoints should be considered as the basis for analysis of realistic WSMs.",
        "positive": "First-principles wavevector- and frequency-dependent\n  exchange-correlation kernel for jellium at all densities: We propose a spatially and temporally nonlocal exchange-correlation (xc)\nkernel for the spin-unpolarized fluid phase of ground-state jellium, for use in\ntime-dependent density functional and linear response calculations. The kernel\nis constructed to satisfy known properties of the exact xc kernel, to\naccurately describe the correlation energies of bulk jellium, and to satisfy\nfrequency-moment sum rules at a wide range of bulk jellium densities, including\nthose low densities that display strong correlation and symmetry breaking.\nThese effects are easier to understand in the simple jellium model than in real\nsystems. All exact constraints satisfied by the recent MCP07 kernel [A.\nRuzsinszky, et al., Phys. Rev. B 101, 245135 (2020)] are maintained in the new\nrevised MCP07 (rMCP07) kernel, while others are added. The revision\n$f_\\mathrm{xc}^\\mathrm{rMCP07}(q,\\omega)$ differs from MCP07 only for non-zero\nfrequencies $\\omega$. Only at densities much lower than those of real bulk\nmetals is the frequency dependence of the kernel important for the correlation\nenergy of jellium. As the wavevector $q$ tends to zero, the kernel has a $-4\\pi\n\\alpha(\\omega)/q^2$ divergence whose frequency-dependent ultranonlocality\ncoefficient $\\alpha(\\omega)$ vanishes in jellium, and is predicted by rMCP07 to\nbe extremely small for the real metals Al and Na.}"
    },
    {
        "anchor": "Empirical Tight-Binding Parameters for Wurtzite group III-V(non-Nitride)\n  and IV Materials: Many commonly used nearest neighbor tight binding models for cubic\nsemiconductors often result in inaccurate band structures when transferred to\nhexagonal polytypes. The resulting bandgaps are systematically too small, and\nin some cases calculations may erroneously predict a metal for the wurtzite\npolytype. We have calculated a set of $\\rm spds^*$ tight binding parameters for\nthe hexagonal phases of non-nitride III-V and group V semiconductors fit to\nexperimental data and empirical pseudopotential calculations. Our fitting\nprocedure constrains the parameters to be as close as possible to those for the\ncubic polytype so as to make the the parameters maximally transferable. Our\nparameters, when combined with the existing cubic parameters, provide a model\nsuitable for modeling the electronic structure of polytypic heterostructures\ncontaining both the wurtzite and zincblende crystal phases.",
        "positive": "On-demand quantum spin Hall insulators controlled by two-dimensional\n  ferroelectricity: The coexistence of ferroelectric and topological orders in two-dimensional\n(2D) atomic crystals allows non-volatile and switchable quantum spin Hall\nstates. Here we offer a general design principle for 2D bilayer\nheterostructures that can host ferroelectricity and nontrivial band topology\nsimultaneously using only topologically trivial building blocks. The built-in\nelectric field arising from the out-of-plane polarization across the\nheterostrucuture enables a robust control of the band gap size and band\ninversion strength, which can be utilized to manipulate topological phase\ntransitions. Using first-principles calculations, we demonstrate a series of\nbilayer heterostructures are 2D ferroelectric topological insulators (2DFETIs)\ncharacterized with a direct coupling between band topology and polarization\nstate. We propose a few 2DFETI-based quantum electronics including domain-wall\nquantum circuits and topological memristor."
    },
    {
        "anchor": "Silicon-nitride photonic circuits interfaced with monolayer MoS$_2$: We report on the integration of monolayer molybdenum disulphide with silicon\nnitride microresonators assembled by visco-elastic layer transfer techniques.\nEvanescent coupling from the resonator mode to the monolayer is confirmed\nthrough measurements of cavity transmission. The absorption of the monolayer\nsemiconductor flakes in this geometry is determined to be 850 dB/cm, which is\nlarger than that of graphene and black phosphorus with the same thickness. This\ntechnique can be applied to diverse monolayer semiconductors for assembling\nhybrid optoelectronic devices such as photodetectors and modulators operating\nover a wide spectral range.",
        "positive": "Ductile fracture modeling by phase field, Hencky strain elasticity and\n  finite J2 plasticity using nonlocal operator method: A phase field model for ductile fracture considering Hencky strain and finite\nJ2 plasticity is presented using the nonlocal operator method. A variational\nderivation of J2 plasticity at finite strain with a phase field model is\nperformed. The method includes a logarithmic strain tensor and an exponential\nmapping in the plasticity evolution. A spectral decomposition based algorithm\nfor computing the first and second order derivatives of the composite matrix\nfunction is implemented. A consistent tangential stiffness matrix is derived\nand used in Newton-Raphson iterations. Several numerical examples are performed\nto validate the method, including notched single-edged plates with brittle\nfracture or ductile fracture and necking of a bar with/without phase field\nmodel."
    },
    {
        "anchor": "Spin configurations in hard-soft coupled bilayer systems: from rigid\n  magnet to exchange spring transitions: We investigate equilibrium properties of an exchange-spring magnetic system\nconstituted of a soft layer (e.g. Fe) of a given thickness on top of a hard\nmagnetic layer (e.g. FePt). The magnetization profile M(z) as a function of the\natomic position ranging from the bottom of the hard layer to the top of the\nsoft layer is obtained in two cases with regard to the hard layer: i) in the\ncase of a rigid interface (the FePt layer is a single layer), the profile is\nobtained analytically as the exact solution of a sine-Gordon equation with\nCauchy's boundary conditions. Additional numerical simulations also confirm\nthis result. Asymptotic expressions of M(z) show a linear behavior near the\nbottom and the top of the soft layer. In addition, a critical value of the\nnumber of atomic planes in the soft layer, that is necessary for the onset of\nspin deviations, is obtained in terms of the anisotropy and exchange coupling\nbetween the adjacent plane in the soft layer. ii) in the case of a relaxed\ninterface (the FePt layer is a multilayer), the magnetization profile is\nobtained numerically for various Fe and FePt films thicknesses and applied\nfield.",
        "positive": "Chemical capacitance proposed for manganite-based ceramics: The measured value of effective electric permittivity \\varepsilon_{eff} of\nseveral compounds, e.g., (BiNa)(MnNb)O_{3}, (BiPb)(MnNb)O_{3}, and BiMnO_{3}\nincreases from a value \\approx 10-100 at the low temperature range (100-300 K)\nup to the high value reaching the value 10^5 at high temperature range, e.g.,\n500-800 K. Such features suggest the manifestation of thermally activated space\ncharge carriers, which effect the measured capacitance. The measured high-value\neffective permittivity of several manganite compounds can be ascribed to the\nchemical capacitance C_{\\mu}=e^2\\partial N_{i}/\\partial \\mu_{i} expressed in\nterms of the chemical potential \\mu. The chemical capacitance C_{\\mu}^{(cb)} =\ne^2 n_{C}/k_{B}T depends on temperature when the conduction electrons with\ndensity n_{C} = N_{C} \\exp(\\mu_{n}- E_{C})/k_{B}T are considered. The\nexperimental results obtained for the manganite compounds, at high temperature\nrange, are discussed in the framework of the chemical capacitance model.\nHowever, the measured capacitance dependence on geometrical factors is analysed\nfor BiMnO_{3} indicating that the non-homogeneous electrostatic capacitor model\nis valid in 300-500 K range."
    },
    {
        "anchor": "Disentangling nonradiative recombination processes in Ge micro-crystals\n  on Si substrates: We address nonradiative recombination pathways by leveraging surface\npassivation and dislocation management in micron-scale arrays of Ge crystals\ngrown on deeply patterned Si substrates. The time decay photoluminescence (PL)\nat cryogenic temperatures discloses carrier lifetimes approaching 45 ns in\nband-gap engineered Ge micro-crystals. This investigation provides compelling\ninformation about the competitive interplay between the radiative band-edge\ntransitions and the trapping of carriers by dislocations and free surfaces.\nFurthermore, an in-depth analysis of the temperature dependence of the PL,\ncombined with capacitance data and finite difference time domain modeling,\ndemonstrates the effectiveness of GeO2 in passivating the surface of Ge and\nthus in enhancing the room temperature PL emission.",
        "positive": "Using Density Functional Theory to Model Realistic TiO2 Nanoparticles,\n  Their Photoactivation and Interaction with Water: Computational modeling of titanium dioxide nanoparticles of realistic size is\nextremely relevant for the direct comparison with experiments but it is also a\nrather demanding task. We have recently worked on a multistep/scale procedure\nto obtain global optimized minimum structures for chemically stable spherical\ntitania nanoparticles of increasing size, with diameter from 1.5 nm (~300\natoms) to 4.4 nm (~4000 atoms). We use first self-consistent-charge density\nfunctional tight-binding (SCC-DFTB) methodology to perform thermal annealing\nsimulations to obtain globally optimized structures and then hybrid density\nfunctional theory (DFT) to refine them and to achieve high accuracy in the\ndescription of structural and electronic properties. This allows also to assess\nSCC-DFTB performance in comparison with DFT(B3LYP) results. As a further step,\nwe investigate photoexcitation and photoemission processes involving\nelectron/hole pair formation, separation, trapping and recombination in the\nnanosphere of medium size by hybrid DFT. Finally, we show how a recently\ndefined new set of parameters for SCC-DFTB allows for a proper description of\ntitania/water multilayers interface, which paves the way for modeling large\nrealistic nanoparticles in aqueous environment."
    },
    {
        "anchor": "Auger neutralization and ionization processes for charge exchange\n  between slow noble gas atoms and solid surfaces: Electron and energy transfer processes between an atom or molecule and a\nsurface are extremely important for many applications in physics and chemistry.\nTherefore a profound understanding of these processes is essential in order to\nanalyze a large variety of physical systems. The microscopic description of the\ntwo-electron Auger processes, leading to neutralization/ionization of an\nion/neutral atom in front of a solid surface, has been a long-standing problem.\nIt can be dated back to the 1950s when H. D. Hagstrum proposed to use the\ninformation contained in the spectrum of the electrons emitted during the\nneutralization of slow noble gas ions as a surface analytical tool\ncomplementing photoelectron spectroscopy. However, only recently a\ncomprehensive description of the Auger neutralization mechanism has been\nachieved by the combined efforts of theoretical and experimental methods. In\nthis article we review the theoretical models for this problem, stressing how\ntheir outcome compare with experimental results. We also analyze the inverse\nproblem of Auger ionization. We emphasize the understanding of the key\nquantities governing the processes and outline the challenges remaining. This\nopens new perspectives for future developments of theoretical and experimental\nwork in this field.",
        "positive": "Order-Disorder Competitive Cooperation in Equiatomic 3d-Transition-Metal\n  Quaternary Alloys: Phase Stability and Electronic Structure: We use high-throughput first-principles sampling to investigate competitive\nfactors that determine the crystal structure of high-entropy alloys (HEAs) and\nthe energetics dependence of the stable phase on the atomic configuration of\nfully ordered L1$_2$, D0$_{22}$, and random solid solution (RSS) phases of\nequiatomic quaternary alloys comprising four of the six constituent elements\n(Cr, Mn, Fe, Co, Ni, and Cu). Considering the configurational entropy, we\ndemonstrate that valence electron concentration (VEC) and temperature are\ncrucial to determine the phase stability of HEAs at finite temperatures,\nwherein the ordered phases are energetically more favorable than RSS phases.\nSome D0$_{22}$ phases with high VEC are energetically more stable than L1$_2$\nphases, though both phases are metastable. Further, we explore magnetic\nconfigurations to identify the origin of the enthalpy term. The calculations\nreveal that ordered phases comprising antiferromagnetic atoms surrounded by\nferromagnetic atoms are energetically stable. The quantitative\nstructure--property relationship is also discussed."
    },
    {
        "anchor": "Modulation of the thermodynamic, kinetic and magnetic properties of the\n  hydrogen monomer on graphene by charge doping: The thermodynamic, kinetic and magnetic properties of the hydrogen monomer on\ndoped graphene layers were studied by ab initio simulations. Electron doping\nwas found to heighten the diffusion potential barrier, while hole doping lowers\nit. However, both kinds of dopings heighten the desorption potential barrier.\nThe underlying mechanism was revealed by investigating the effect of doping on\nthe bond strength of graphene and on the electron transfer and the coulomb\ninteraction between the hydrogen monomer and graphene. The kinetic properties\nof H and D monomers on doped graphene layers during both the annealing process\n(annealing time $t_0 =$300 s) and the constant-rate heating process (heating\nrate $\\alpha =$1.0 K/s) were simulated. Both electron and hole dopings were\nfound to generally increase the desorption temperatures of hydrogen monomers.\nElectron doping was found to prevent the diffusion of hydrogen monomers, while\nthe hole doping enhances their diffusion. Macroscopic diffusion of hydrogen\nmonomers on graphene can be achieved when the doping-hole density reaches\n$5.0\\times10^{13}$ cm$^{-2}$. The magnetic moment and exchange splitting were\nfound to be reduced by both electron and hole dopings, which was explained by a\nsimple exchange model. The study in this report can further enhance the\nunderstanding of the interaction between hydrogen and graphene and is expected\nto be helpful in the design of hydrogenated-graphene-based devices.",
        "positive": "Quantum Manifestation of Elastic Constants in Nanostructures: Generally, there are two distinct effects in modifying the properties of\nlow-dimensional nanostructures: surface effect (SS) due to increased\nsurface-volume ratio and quantum size effect (QSE) due to quantum confinement\nin reduced dimension. The SS has been widely shown to affect the elastic\nconstants and mechanical properties of nanostructures. Here, using Pb nanofilm\nand graphene nanoribbon as model systems, we demonstrate the QSE on the elastic\nconstants of nanostructures by first-principles calculations. We show that\ngenerally QSE is dominant in affecting the elastic constants of metallic\nnanostructures while SS is more pronounced in semiconductor and insulator\nnanostructures. Our findings have broad implications in quantum aspects of\nnanomechanics."
    },
    {
        "anchor": "Spinodal decomposition and domain coarsening in a multi-layer\n  Cahn-Hilliard model for lithium intercalation in graphite: During the intercalation of lithium in layered host materials such as\ngraphite, lithium atoms can move within the plane between two neighboring\ngraphene sheets, but cannot cross the sheets. Repulsive interactions between\natoms in different layers lead to the existence of ordered phases called\n\"stages\", with stage $n$ consisting of one filled layer out of $n$, the others\nbeing empty. Such systems can be conveniently described by a multi-layer\nCahn-Hilliard model, which can be seen as a mean-field approximation of a\nlattice-gas model with intra- and interlayer interactions between lithium\natoms. In this paper, the dynamics of stage formation after a rapid quench to\nlower temperature is analyzed, both by a linear stability analysis and by\nnumerical simulation of the full equations. In particular, the competition\nbetween stages 2 and 3 is studied in detail. The linear stability analysis\npredicts that stage 2 always grows the fastest, even in the composition range\nwhere stage 3 is the stable equilibrium state. This is borne out by the\nnumerical simulations, which show that stage 3 emerges only during the\nnon-linear coarsening of stage 2. Some consequences of this finding for the\ncharge-discharge dynamics of electrodes in batteries are briefly discussed.",
        "positive": "Room-temperature giant magnetotranstance effect in single-phase\n  multiferroics: Single-phase multiferroic materials are usually considered useless because of\nthe weak magnetoelectric effects, low operating temperature, and small electric\npolarization induced by magnetic orders. As a result, current studies on\napplications of the magnetoelectric effects are mainly focusing on multiferroic\nheterostructures and composites. Here we report a room-temperature giant effect\nin response to external magnetic fields in single-phase multiferroics. A low\nmagnetic field of 1000 Oe applied on the spin-driven multiferroic hexaferrites\nBaSrCo2Fe11AlO22 and Ba0.9Sr1.1Co2Fe11AlO22 is able to cause a huge change in\nthe linear magnetoelectric coefficient by several orders, leading to a giant\nmagnetotranstance (GMT) effect at room temperature. The GMT effect is\ncomparable to the well-known giant magnetoresistance (GMR) effect in magnetic\nmultilayers, and thus opens up a door toward practical applications for\nsingle-phase multiferroics."
    },
    {
        "anchor": "Machine-learning interatomic potential for molecular dynamics simulation\n  of ferroelectric KNbO3 perovskite: Ferroelectric perovskites have been ubiquitously applied in piezoelectric\ndevices for decades, among which, eco-friendly lead-free (K,Na)NbO3-based\nmaterials have been recently demonstrated to be an excellent candidate for\nsustainable development. Molecular dynamics is a versatile theoretical\ncalculation approach for the investigation of the dynamical properties of\nferroelectric perovskites. However, molecular dynamics simulation of\nferroelectric perovskites has been limited to simple systems, since the\nconventional construction of interatomic potential is rather difficult and\ninefficient. In the present study, we construct a machine-learning interatomic\npotential of KNbO3 (as a representative system of (K,Na)NbO3) by using a deep\nneural network model. Including first-principles calculation data into the\ntraining dataset ensures the quantum-mechanics accuracy of the interatomic\npotential. The molecular dynamics based on machine-learning interatomic\npotential shows good agreement with the first-principles calculations, which\ncan accurately predict multiple fundamental properties, e.g., atomic force,\nenergy, elastic properties, and phonon dispersion. In addition, the interatomic\npotential exhibits satisfactory performance in the simulation of domain wall\nand temperature-dependent phase transition. The construction of interatomic\npotential based on machine learning could potentially be transferred to other\nferroelectric perovskites and consequently benefits the theoretical study of\nferroelectrics.",
        "positive": "All Topological Bands of All Nonmagnetic Stoichiometric Materials: Topological Quantum Chemistry and Symmetry-Based Indicators have facilitated\nlarge-scale searches for materials with topological properties at the Fermi\nenergy ($E_{F}$). We report the completion of a publicly accessible catalog of\nstable and fragile topology in all of the bands both at and away from $E_{F}$\nin the 96,196 processable entries in the Inorganic Crystal Structure Database.\nOur calculations represent the completion of the symmetry-indicated band\ntopology of known nonmagnetic materials, and enable the discovery of\nrepeat-topological and supertopological materials, which include rhombohedral\nbismuth and Bi$_2$Mg$_3$. We find that 52.65% of all materials are topological\nat $E_{F}$, roughly $2/3$ of bands across all materials exhibit\nsymmetry-indicated stable topology, and that 87.99% of all materials contain at\nleast one stable or fragile topological band."
    },
    {
        "anchor": "Phonon Self-Energy Corrections: To Screen, or Not to Screen: First-principles calculations of phonons are often based on the adiabatic\napproximation and on Brillouin-zone samplings that might not always be\nsufficient to capture the subtleties of Kohn anomalies. These shortcomings can\nbe addressed through corrections to the phonon self-energy arising from the\nlow-energy electrons. The exact self-energy involves a product of a bare and a\nscreened electron-phonon vertex [Rev. Mod. Phys. 89, 015003 (2017)]; still,\ncalculations often employ two adiabatically screened vertices, which have been\nproposed as a reliable approximation for self-energy differences [Phys. Rev. B\n82, 165111 (2010)]. We assess the accuracy of both approaches in estimating the\nphonon spectral functions of model Hamiltonians and the adiabatic\nlow-temperature phonon dispersions of monolayer TaS$_2$ and doped MoS$_2$. We\nfind that the approximate method yields excellent corrections at low\ncomputational cost, due to its designed error cancellation to first order,\nwhile using a bare vertex could in principle improve these results but is\nchallenging in practice. We offer an alternative strategy based on downfolding\nto partially screened phonons and interactions [Phys. Rev. B 92, 245108\n(2015)]. This is a natural scheme to include electron-electron interactions and\ntackle phonons in strongly correlated materials and the frequency dependence of\nthe electron-phonon vertex.",
        "positive": "Interaction of martensitic microstructures in adjacent grains: It is often observed that martensitic microstructures in adjacent polycrystal\ngrains are related. For example, micrographs of Arlt exhibit propagation of\nlayered structures across grain boundaries in the cubic-to-tetragonal phase\ntransformation in $\\rm BaTiO_3$. Such observations are related to requirements\nof compatibility of the deformation at the grain boundary. Using a\ngeneralization of the Hadamard jump condition, this is explored in the\nnonlinear elasticity model of martensitic transformations for the case of a\nbicrystal with suitably oriented columnar geometry, in which the microstructure\nin both grains is assumed to involve just two martensitic variants, with a\nplanar or non-planar interface between the grains."
    },
    {
        "anchor": "Successive field-induced transitions in BiFeO$_{3}$ around room\n  temperature: The effects of high magnetic fields applied perpendicular to the spontaneous\nferroelectric polarization on single crystals of BiFeO$_3$ were investigated\nthrough magnetization, magnetostriction, and neutron diffraction measurements.\nThe magnetostriction measurements revealed lattice distortion of $2\\times\n10^{-5}$, during the reorientation process of the cycloidal spin order by\napplied magnetic fields. Furthermore, anomalous changes in magnetostriction and\nelectric polarization at a larger field demonstrate an intermediate phase\nbetween cycloidal and canted antiferromagnetic states, where a large\nmagnetoelectric effect was observed. Neutron diffraction measurements clarified\nthat incommensurate spin modulation along [110] direction in the cycloidal\nphase becomes commensurate in the intermediate phase. Theoretical calculations\nbased on the standard spin Hamiltonian of this material suggest an\nantiferromagnetic cone-type spin order in the intermediate phase.",
        "positive": "Oleylamine aging of PtNi nanoparticles giving enhanced functionality for\n  the oxygen reduction reaction: We report a rapid solution-phase strategy to synthesize alloyed PtNi\nnanoparticles which demonstrate outstanding functionality for the oxygen\nreduction reaction (ORR). This one-pot co-reduction colloidal synthesis results\nin a monodisperse population of single-crystal nanoparticles of rhombic\ndodecahedral morphology, with Pt enriched edges and compositions close to\nPt1Ni2. We use nanoscale 3D compositional analysis to reveal for the first time\nthat oleylamine (OAm)-aging of the rhombic dodecahedral Pt1Ni2 particles\nresults in Ni leaching from surface facets, producing aged particles with\nconcave faceting, an exceptionally high surface area and a composition of\nPt2Ni1. We show that the modified atomic nanostructures catalytically\noutperform the original PtNi rhombic dodecahedral particles by more than 2-fold\nand also yield improved cycling durability. Their functionality for the ORR far\nexceeds commercially available Pt/C nanoparticle electrocatalysts, both in\nterms of mass-specific activities (up to a 25-fold increase) and intrinsic\narea-specific activities (up to a 27-fold increase)."
    },
    {
        "anchor": "Anisotropic magnetocaloric effect of CrI$_{3}$: A theoretical study: CrI$_{3}$ is considered to be a promising candidate for spintronic devices\nand data storage. We derived the Heisenberg Hamiltonian for CrI$_{3}$ from\ndensity functional calculations using the Liechtenstein formula. Moreover, the\nMonte--Carlo simulations with the Sucksmith--Thompson method were performed to\nanalyze the effect of magnetic anisotropy energy on the thermodynamic\nproperties. Our method successfully reproduced the negative sign of isothermal\nmagnetic entropy changes when a magnetic field was applied along the hard\nplane. We found that the temperature dependence of the magnetocrystalline\nanisotropy energy is not negligible at temperatures slightly above the Curie\ntemperature. We clarified that the origin of this phenomenon is attributed to\nanisotropic magnetic susceptibility and magnetization anisotropy. The\ndifference between the entropy change of the easy axis and the hard plane is\nproportional to the temperature dependence of the magnetic anisotropy energy,\nimplying that the anisotropic entropy term is the main source of the\ntemperature dependence of the free energy difference when magnetizing in a\nspecific direction other than the easy axis. We also investigated the magnetic\nsusceptibility that can be used for the characterization of the negative sign\nof the entropy change in the case of a hard plane. The competition of\nmagnetocrystalline anisotropy energy and external magnetic field at low\ntemperature and low magnetic field region causes a high magnetic susceptibility\nas the fluctuation of magnetization. Meanwhile, the anisotropy energy is\nsuppressed at a sufficient magnetic field applied along the hard axis, the\nmagnetization is fully rotated to the direction of the external magnetic field.",
        "positive": "Strong interband interaction in the excitonic insulator phase of\n  Ta$_2$NiSe$_5$: Excitonic insulator (EI) was proposed in 60's as a distinct insulating state\noriginating from pure electronic interaction, but its material realization has\nbeen elusive with extremely few material candidates and with only limited\nevidence such as anomalies in transport properties, band dispersions, or\noptical transitions. We investigate the real-space electronic states of the low\ntemperature phase in Ta$_2$NiSe$_5$ with an atomic resolution to clearly\nidentify the quasiparticle energy gap together with the strong electron-hole\nband renormalization using scanning tunneling microscopy (STM) and spectroscopy\n(STS). These results are in good agreement with the EI transition scenario in\nTa$_2$NiSe$_5$. Our spatially-resolved STS data and theoretical calculations\nreveal further the orbital inversion at band edges, which indicates the exciton\ncondensation close to the Bardeen-Cooper-Schrieffer regime."
    },
    {
        "anchor": "Dissimilar thermal transport properties in $\u03ba$-Ga$_2$O$_3$ and\n  $\u03b2$-Ga$_2$O$_3$ revealed by machine-learning homogeneous nonequilibrium\n  molecular dynamics simulations: The lattice thermal conductivity (LTC) of Ga$_2$O$_3$ is an important\nproperty due to the challenge in the thermal management of high-power devices.\nWe develop machine-learned neuroevolution potentials for single-crystalline\n$\\beta$-Ga$_2$O$_3$ and $\\kappa$-Ga$_2$O$_3$, and apply them to perform\nhomogeneous nonequilibrium molecular dynamics simulations to predict their\nLTCs. The LTC of $\\beta$-Ga$_2$O$_3$ was determined to be 10.3 $\\pm$ 0.2 W/(m\nK), 19.9 $\\pm$ 0.2 W/(m K), and 12.6 $\\pm$ 0.2 W/(m K) along [100], [010], and\n[001], respectively, aligning with previous experimental measurements. For the\nfirst time, we predict the LTC of $\\kappa$-Ga$_2$O$_3$ along [100], [010], and\n[001] to be 4.5 $\\pm$ 0.0 W/(m K), 3.9 $\\pm$ 0.0 W/(m K), and 4.0 $\\pm$ 0.1\nW/(m K), respectively, showing a nearly isotropic thermal transport property.\nThe reduced LTC of $\\kappa$-Ga$_2$O$_3$ versus $\\beta$-Ga$_2$O$_3$ stems from\nits restricted low-frequency phonons up to 5 THz. Furthermore, we find that the\n$\\beta$ phase exhibits a typical temperature dependence slightly stronger than\n$\\sim T^{-1}$, whereas the $\\kappa$ phase shows a weaker temperature\ndependence, ranging from $\\sim T^{-0.5}$ to $\\sim T^{-0.7}$.",
        "positive": "Spin pumping using an Ni80Fe20 thin film annealed in a magnetic field: Spin pumping controlled with the ferromagnetic resonance of an Ni80Fe20 thin\nfilm annealed in a magnetic field was performed in order to investigate the\nsimple and efficient generation method of the pure spin current. At the\nspin-pumping using the Ni80Fe20 on an annealed Pd/Ni80Fe20 stacked structure,\nthe electromotive force due to the inverse spin-Hall effect (ISHE) in the Pd\nwas found to be 30% stronger than that without annealing. When the angle\nbetween the directions of localized magnetic moments in the Ni80Fe20 film and\nthe external magnetic field in the spin-pumping is zero, the spin injection\nefficiency into the Pd layer, i.e., the spin current density generated in the\nPd layer can be the maximum. The annealing in a magnetic field is a convenient\ntechnique for increasing the spin current density generated by the spin\npumping."
    },
    {
        "anchor": "Evaluation of the Thermal Stability of TiW/Cu Heterojunctions Using a\n  Combined SXPS and HAXPES Approach: Power semiconductor device architectures require the inclusion of a diffusion\nbarrier to suppress, or at best prevent the interdiffusion between the copper\nmetallisation interconnects and the surrounding silicon substructure. The\nbinary pseudo-alloy of titanium-tungsten (TiW), with $>$70~at.\\% W, is a well\nestablished copper diffusion barrier but is prone to degradation via the\nout-diffusion of titanium when exposed to high temperatures\n($\\geq$400$^\\circ$C). Here, the thermal stability of physical vapour deposited\n(PVD) TiW/Cu bilayer thin films in\nSi/SiO\\textsubscript{2}(50~nm)/TiW(300~nm)/Cu(25~nm) stacks were characterised\nin response to annealing at 400$^\\circ$C for 0.5~h and 5~h, using a combination\nof soft and hard X-ray photoelectron spectroscopy (SXPS and HAXPES) and\ntransmission electron microscopy (TEM). Results show that annealing promoted\nthe segregation of titanium out of the TiW and interdiffusion into the copper\nmetallisation. Titanium was shown be driven toward the free copper surface,\naccumulating there and forming a titanium oxide overlayer upon exposure to air.\nAnnealing for longer timescales promoted a greater out-diffusion of titanium\nand a thicker oxide layer to grow on the copper surface. However, interface\nmeasurements suggest that the diffusion is not significant enough to compromise\nthe barrier integrity and the TiW/Cu interface remains stable even after 5~h of\nannealing.",
        "positive": "Ferroelectric domain inversion and its stability in lithium niobate thin\n  film on insulator with different thicknesses: Ferroelectric domain inversion and its effect on the stability of lithium\nniobate thin films on insulator (LNOI) are experimentally characterized. Two\nsets of specimens with different thicknesses varying from submicron to microns\nare selected. For micron thick samples (~28 um), domain structures are achieved\nby pulsed electric field poling with electrodes patterned via photolithography.\nNo domain structure deterioration has been observed for a month as inspected\nusing polarizing optical microscopy and etching. As for submicron (540 nm)\nfilms, large-area domain inversion is realized by scanning a biased conductive\ntip in a piezoelectric force microscope. A graphic processing method is taken\nto evaluate the domain retention. A domain life time of 25.0 h is obtained and\npossible mechanisms are discussed. Our study gives a direct reference for\ndomain structure-related applications of LNOI, including guiding wave nonlinear\nfrequency conversion, nonlinear wavefront tailoring, electro-optic modulation,\nand piezoelectric devices."
    },
    {
        "anchor": "Lowering the hydrogen desorption temperature of NH3BH3 through B-group\n  substitutions: We present ab initio results for substitutions in the promising\nhydrogen-storage material NH3BH3 to lower its hydrogen desorption temperature.\nSubstitutions have already been investigated with significant success recently,\nbut in all cases a less electronegative element is substituted for the protic\nhydrogen in the NH3 group of NH3BH3. We propose a different route, substituting\nth ehydridic hydrogen in the BH3 group with a more electronegative element. To\nkeep the gravimetric density high, we focus on the second period elements C, N,\nO, and F, all with higher electronegativity compared to H. In addition, we\ninvestigate Cu and S as possible substitutions. Our main results include Bader\ncharge analyses, hydrogen binding energies, and kinetic barriers for the\nhydrogen release reaction in the gas phase as well as in the solid. While the\ndifferent substituents show varying effects on the kinetic barrier and thus\ndesorption temperature - some overshoot our goal while others have little\neffect - we identify Cu as a very promising substituent, which lowers the\nreaction barrier by approximately 37% compared to NH3BH3 and thus significantly\ninfluences the hydrogen desorption temperature.",
        "positive": "Highly Complex Magnetic Structures Resulting From Hierarchical Phase\n  Separation in AlCo(Cr)FeNi High Entropy Alloys: Magnetic high entropy alloys (HEAs) are a new category of high-performance\nmagnetic materials, with multi-component concentrated compositions and complex\nmulti-phase structures. Although there have been numerous reports of their\ninteresting magnetic properties, there is very limited understanding about the\ninterplay between their hierarchical multi-phase structures and their local\nmagnetic structures. By employing high spatial resolution correlative magnetic,\nstructural and chemical studies, we reveal the influence of a hierarchically\ndecomposed B2 + A2 structure in an AlCo0.5Cr0.5FeNi HEA on the formation of\nmagnetic vortex states within individual A2 (disordered BCC) precipitates,\nwhich are distributed in an ordered B2 matrix that is weakly ferromagnetic.\nNon-magnetic or weakly ferromagnetic B2 precipitates in large magnetic domains\nof the A2 phase, and strongly magnetic Fe-Co-rich interphase A2 regions, are\nalso observed. These results provide important insight into the origin of\ncoercivity in this HEA, which can be attributed to a complex magnetization\nprocess that includes the successive reversal of magnetic vortices."
    },
    {
        "anchor": "Second-Order Topological Insulator in Two-Dimensional C2N and Its\n  Derivatives: Quadrupole phase, as a novel high-order topological phase, exhibits\nnontrivial gapless states at the boundaries whose dimension is lower than bulk\nby two. However, this phase has not been observed experimentally in\ntwo-dimensional (2D) materials up to now. In this work, using first-principles\ncalculations and tight-binding (TB) model, we propose that the experimentally\nsynthesized C2N is a 2D quadrupole topological insulator with one-dimensional\ngapped edge states and zero-dimensional gapless corner states. C2N is found to\nhave a large bulk gap of 2.45 eV and an edge gap of 0.32 eV, making it an\nexcellent candidate to evidently present the nontrivial corner states in\nexperiments. The robustness of the corner states against the edge disorders has\nbeen explicitly identified. Moreover, another three C2N-like materials are also\nfound to host the nontrivial quadrupole phase including an experimentally\nsynthesized material aza-fused microporous polymers (CMP). The four 2D\nquadrupole topological phases proposed in our present work provide excellent\ncandidates for studying the novel high-order topological properties in future\nexperiments.",
        "positive": "Local Electronic Structure of PbVO3, a New Member of PbTiO3 Family,\n  studied by XANES/ELNES: Recently an interesting multi-ferroic system PbVO3 [Chem. Mater. 2004] was\nsuccessfully prepared using a high-pressure and high-temperature technique. The\ncrystallographic features were reported. In this note we concentrate on the\ntheoretical XANES spectra by considering the K-edge of Vanadium. The\ntetragonality [c/a=1.229 at 300 K] of PbVO3 is the largest in the PbTiO3 family\nof compounds. Thus one is led naturally to examine the effect of the change of\ntetragonality and the axial oxygen position on the electronic structure [i.e.\nXANES spectrum]. We study this effect in two ways. At a given temperature we\nvary the tetragonality and the axial oxygen position and quantify it in terms\nof XANES difference spectrum. Secondly, we compute the XANES spectra at three\ndifferent temperatures, 90 K, 300 K, and 530 K and quantify the change in terms\nof the difference spectrum. We note that in this compound the tetragonality\nincreases almost monotonically with temperature from 12 K to 570 K without\ntransition to the cubic phase under ambient pressure. A key objective of the\ncurrent investigation is to gain an understanding of various absorption\nfeatures in the vicinity of K-edge of V, in terms of valence, local site\nsymmetry, local coordination geometry, local bond distances, charge transfer,\nand local projected density of states. We consider both the polarized and the\nunpolarized XANES spectra. In short we have performed a local electronic study,\nwhich nicely complements the crystallographic features reported recently in\nPbVO3."
    },
    {
        "anchor": "Partial Hydrogenation of N-heteropentacene: Impact on molecular packing\n  and electronic structure: Four-nitrogen-containing 5,6,13,14-Tetraazapentacene (BTANC) has attracted\nattention as a new n-type organic semiconductor with a rigid crystalline phase\ndue to intermolecular CH-N hydrogen bonding. However, in the thin film\ntransistor of BTANC, poor carrier transport properties and low stability in the\nambient condition have been reported so far; thus further refining and\nunderstanding of the thin film of BTANC will be required. Here, by means of\ncarefully-controlled vacuum deposition of BTANC in the narrow window of\ntemperature avoiding impurity sublimation and thermal degradation of molecules,\nwe produced a well-defined monolayer on Cu(111) for molecular-level\ninvestigations. Synchrotron photoemission of the monolayer revealed a\nnoticeable alteration of the chemical state of N atoms, which is unexpected for\nthe pure BTANC molecule. In addition, molecular imaging of the monolayer by\nscanning tunneling microscope (STM) revealed that the molecular packing\nstructure in the monolayer significantly differed from that in the single\ncrystal of BTANC. These observations can be interpreted as a result of the\npartial hydrogenation of N atoms in BTANC and the emergence of the NH-N type\nintermolecular hydrogen bonding in the monolayer. These findings will provide a\ngeneral remark and strategy to control the molecular packing structure and\nelectronic property in the molecular films of the nitrogen-containing acenes,\nby means of controlled hydrogenation.",
        "positive": "In-situ alignment of anisotropic hard magnets of 3D printed magnets: Within this work, we demonstrate in-situ easy-axis alignment of\nsingle-crystal magnetic particles inside a polymer matrix using fused filament\nfabrication. Two different magnetic materials are investigated: (i) Strontium\nhexaferrite inside a PA6 matrix, fill grade: 49 vol% and (ii) Samarium iron\nnitride inside a PA12 matrix, fill grade: 44 vol%. In the presence of the\nexternal alignment field, the strontium hexaferrite particles inside the PA6\nmatrix can be well aligned with a ratio of remanent magnetization to saturation\nmagnetization of 0.7. No significant alignment for samarium iron nitride could\nbe achieved. The results show the feasibility to fabricate magnets with\narbitrary and locally defined easy axis using fused filament fabrication since\nthe permanent magnets used for the alignment (or alternatively an\nelectromagnet) can be mounted on a rotatable platform."
    },
    {
        "anchor": "A Computational Framework for Automation of Point Defect Calculations: A complete and rigorously validated open-source Python framework to automate\npoint defect calculations using density functional theory has been developed.\nThe framework provides an effective and efficient method for defect structure\ngeneration, and creation of simple yet customizable workflows to analyze defect\ncalculations. The package provides the capability to compute widely-accepted\ncorrection schemes to overcome finite-size effects, including (1) potential\nalignment, (2) image-charge correction, and (3) band filling correction to\nshallow defects. Using Si, ZnO and In$_2$O$_3$ as test examples, we demonstrate\nthe package capabilities and validate the methodology.",
        "positive": "Asymmetric scattering behaviors of spin wave dependent on magnetic\n  vortex chirality: In this letter, an asymmetric spin wave scattering behaviors caused by vortex\nchirality are investigated in cross-shaped ferromagnetic system. In the system,\nfour scattering behaviors are found, 1) asymmetric skew scattering, depending\non the polarity of vortex core, 2) back scattering (reflection), depending on\nthe vortex core stiffness, 3) side deflection scattering, depending on\nstructural symmetry of the vortex circulation, and 4) geometrical scattering,\ndepending on waveguide structure. The first and second scattering behaviors are\nattributed to nonlinear topological magnon spin Hall effect related to magnon\nspin-transfer torque effect, which has value for magnonic exploration and\napplication."
    },
    {
        "anchor": "Atomistic study on the cross-slip process of a screw <a> dislocation in\n  magnesium: The cross-slip process of a screw $<$a$>$ dislocation from the basal to the\nprismatic plane in magnesium was studied using the density functional theory\nand the molecular dynamics calculations. An atomistic method for calculating\nthe total Peierls energy map has been devised to track the transition path of a\ndissociated and/or constricted screw $<$a$>$ dislocation in the cross-slip\nprocess. The barrier of a screw $<$a$>$ dislocation from the basal to the\nprismatic plane is estimated by the density functional theory for the first\ntime to be $61.4\\pm 2.0$ meV per Burgers vector length. The activation enthalpy\nfor the cross slip is calculated using a line tension model based on the\ndensity functional theory to be $1.4$ to $1.7$ eV, which is in reasonable\nagreement with experiments. On the basis of the results, the effect of\ntemperature on the cross-slip process of the dissociated screw $<$a$>$\ndislocation on the basal plane is studied in detail using the molecular\ndynamics method with the embedded-atom-method (EAM) interatomic potential, in\nwhich the critical resolved shear stress for the cross slip is evaluated. It is\nconfirmed that the bowed-out dislocation line on the prismatic plane consists\nof slightly dissociated rectilinear segments with connecting jogs at low\ntemperatures and, as the temperature rises, the curved dislocation line becomes\nsmooth with many segments. The motion of an $<$a$>$ dislocation on the\nprismatic plane is jerky in the low temperature region, while it is retarded by\nthe formation of the largely dissociated plateau segment above the room\ntemperature. A large reduction of the critical shear stress for the cross slip\nis obtained when the $<$a$>$ screw dislocation interacts with a hard-sphere\nparticle placed on the basal plane in the low temperature region",
        "positive": "An approximate hard sphere method for densely packed granular flows: The simulation of granular media is usually done either with event-driven\ncodes that treat collisions as instantaneous but have difficulty with very\ndense packings, or with molecular dynamics methods that approximate rigid\ngrains using a stiff viscoelastic spring. There is a little-known method that\ncombines several collision events into a single timestep in order to retain the\ninstantaneous collisions of event-driven dynamics but also be able to handle\ndense packings. However, it is poorly characterized as to its regime of\nvalidity and failure modes. We present a modification of this method to reduce\nthe introduction of overlap error, and test it using the problem of 2D granular\nCouette flow, a densely packed system that has been well-characterized by\nprevious work. We find that this method can successfully replicate the results\nof previous work up to the point of jamming, and that it can do so a factor of\n10 faster than comparable MD methods."
    },
    {
        "anchor": "Computational study of Electron Paramagnetic Resonance parameters for Mg\n  and Zn impurities in $\u03b2$-Ga$_2$O$_3$: A computational study of the electron paramagnetic resonance (EPR)\n$g$-tensors and hyperfine tensors in Mg and Zn doped $\\beta$-Ga$_2$O$_3$ is\npresented. While Mg has been found previously to prefer the octahedral site, we\nfind here that Zn prefers the tetrahedral substitutional site. The EPR\nsignatures are found to be distinct for the two sites. Good agreement with\nexperiment is found for the $g$-tensor and hyperfine interaction for\nMg$_\\mathrm{Ga2}$ and predictions are made for the Zn case.",
        "positive": "Phonon and Elastic Instabilities in MoC and MoN: We present several results related to the instability of MoC and MoN in the\nB1 (sodium chloride) structure. These compounds were proposed as potential\nsuperconductors with moderately high transition temperatures. We show that the\nelastic instability in B1-structure MoN, demonstrated several years ago,\npersists at elevated pressures, thus offering little hope of stabilizing this\nmaterial without chemical doping. For MoC, another material for which\nstoichiometric fabrication in the B1-structure has not proven possible, we find\nthat all of the cubic elastic constants are positive, indicating elastic\nstability. Instead, we find X-point phonon instabilities in MoC (and in MoN as\nwell), further illustrating the rich behavior of carbo-nitride materials. We\nalso present additional electronic structure results for several transition\nmetal (Zr, Nb and Mo) carbo-nitride systems and discuss systematic trends in\nthe properties of these materials. Deviations from strict electron counting\ndependencies are apparent."
    },
    {
        "anchor": "Understanding long-time vacancy aggregation in iron: a kinetic\n  activation-relaxation technique study: Vacancy diffusion and clustering processes in body-centered-cubic (bcc) Fe\nare studied using the kinetic activation-relaxation technique (k-ART), an\noff-lattice kinetic Monte Carlo method with on-the-fly catalog building\ncapabilities. For monovacancies and divacancies, k-ART recovers previously\npublished results while clustering in a 50-vacancy simulation box agrees with\nexperimental estimates. Applying k-ART to the study of clustering pathways for\nsystems containing from one to six vacancies, we find a rich set of diffusion\nmechanisms. In particular, we show that the path followed to reach a\nhexavacancy cluster influences greatly the associated mean-square displacement.\nAggregation in a 50-vacancy box also shows a notable dispersion in relaxation\ntime associated with effective barriers varying from 0.84 to 1.1 eV depending\non the exact pathway selected. We isolate the effects of long-range elastic\ninteractions between defects by comparing to simulations where those effects\nare deliberately suppressed. This allows us to demonstrate that in bcc Fe,\nsuppressing long-range interactions mainly influences kinetics in the first 0.3\nms, slowing down quick energy release cascades seen more frequently in full\nsimulations, whereas long-term behavior and final state are not significantly\naffected.",
        "positive": "Memory effect under pressure in low density amorphous silicon: Our investigations on porous Si show that on increase of pressure it\nundergoes crystalline phase transitions instead of pressure induced\namorphization - claimed earlier, and the amorphous phase appears only on\nrelease of pressure. This amorphous phase, when subjected to higher pressures,\ntransforms reversibly to a higher coordinated primitive hexagonal phase showing\na kind of memory effect which may be the only example of its kind in the\nelemental solids. First principles calculations and thermodynamic arguments\nhelp understand these observations."
    },
    {
        "anchor": "Structural and magnetic properties of the (Bi2-xPrx)Ru2O7 pyrochlore\n  solid solution (0 <= x <= 2): We report a detailed study of structural and magnetic properties of the\npyrochlore-type (Bi2-xPrx)Ru2O7 series. Eleven compositions with 0 <= x <= 2\nwere prepared by solid state reaction at 1050 degrees C and found to form a\nsolid solution in the whole range of compositions. Structural refinements from\nX-ray powder diffraction data by the Rietveld method show that the main\nvariation concerns the ruthenium site. Ru-O distances increase and the Ru-O-Ru\nangle (bridging corner-sharing Ru-O octahedra) decreases with increasing\npraseodymium content, in agreement with the metal-semiconductor transition\nobserved previously in this system. Magnetic measurements show that the\nmetallic Pauli paramagnetism of Ru in Bi2Ru2O7 evolves to a magnetism of\nlocalized low spin moments coexisting with the magnetism of Pr3+ cations\nmoments. Strong magnetic correlations are present at high Pr content, as\nillustrated by a N\\'eel temperature of -224 K for Pr2Ru2O7. However no evidence\nof a magnetic ordering was found, suggesting that the end compound Pr2Ru2O7 of\nthe series might stabilize a spin liquid phase.",
        "positive": "Statistical properties of fracture in a random spring model: Using large scale numerical simulations we analyze the statistical properties\nof fracture in the two dimensional random spring model and compare it with its\nscalar counterpart: the random fuse model. We first consider the process of\ncrack localization measuring the evolution of damage as the external load is\nraised. We find that, as in the fuse model, damage is initially uniform and\nlocalizes at peak load. Scaling laws for the damage density, fracture strength\nand avalanche distributions follow with slight variations the behavior observed\nin the random fuse model. We thus conclude that scalar models provide a\nfaithful representation of the fracture properties of disordered systems."
    },
    {
        "anchor": "Explanation of the discrepancy between the measured and atomistically\n  calculated yield stresses in body-centered cubic metals: We propose a mesoscopic model that explains the factor of two to three\ndiscrepancy between experimentally measured yield stresses of BCC metals at low\ntemperatures and typical Peierls stresses determined by atomistic simulations\nof isolated screw dislocations. The model involves a Frank-Read type source\nemitting dislocations that become pure screws at a certain distance from the\nsource and, owing to their high Peierls stress, control its operation. However,\ndue to the mutual interaction between emitted dislocations the group consisting\nof both non-screw and screw dislocations can move at an applied stress that is\nabout a factor of two to three lower than the stress needed for the glide of\nindividual screw dislocations.",
        "positive": "Theory of strain in single-layer transition metal dichalcogenides: Strain engineering has emerged as a powerful tool to modify the optical and\nelectronic properties of two-dimensional crystals. Here we perform a systematic\nstudy of strained semiconducting transition metal dichalcogenides. The effect\nof strain is considered within a full Slater-Koster tight-binding model, which\nprovides us with the band structure in the whole Brillouin zone. From this, we\nderive an effective low-energy model valid around the K point of the BZ, which\nincludes terms up to second order in momentum and strain. For a generic profile\nof strain, we show that the solutions for this model can be expressed in terms\nof the harmonic oscillator and double quantum well models, for the valence and\nconduction bands respectively. We further study the shift of the position of\nthe electron and hole band edges due to uniform strain. Finally, we discuss the\nimportance of spin-strain coupling in these 2D semiconducting materials."
    },
    {
        "anchor": "Near-forward Raman scattering by bulk and surface phonon-polaritons in\n  the model percolation-type ZnBeSe alloy: We study the bulk and surface phonon-polaritons of the Zn0.67Be0.33Se\nzincblende alloy by near-forward Raman scattering. The short (Be-Se) bond\nexhibits a distinct percolation doublet in the conventional backscattering\nRaman spectra, corresponding to a three-mode behavior in total\n[1(Zn-Se),2(Be-Se)] for Zn0.67Be0.33Se. This offers an opportunity to achieve a\nrefined understanding of the phonon-polariton modes of a zincblende alloy\nbeyond the current two-mode approximation, corresponding to a\n[1(Zn-Se),1(Be-Se)] description in the present case. The discussion is\nsupported by contour modeling of the Raman signals of the multi-mode bulk and\nsurface phonon-polaritons within the formalism of the linear dielectric\nresponse.",
        "positive": "Nonlinear response theories and effective pair potentials: We present a general method based on nonlinear response theory to obtain\neffective interactions between ions in an electron gas which can also be\napplied to other systems where an adiabatic separation of time-scales is\npossible. Nonlinear contributions to the interatomic potential are expressed in\nterms of physically meaningful quantities, giving insight in the physical\nproperties of the system. The method is applied to various test cases and is\nfound to improve the standard linear and quadratic response approaches. It also\nreduces the discrepancies previously observed between perturbation theory and\ndensity-functional theory results for the proton-proton pair potentials in\nmetallic environments."
    },
    {
        "anchor": "Ab initio study of shock compressed oxygen: Quantum molecular dynamic simulations are introduced to study the shock\ncompressed oxygen. The principal Hugoniot points derived from the equation of\nstate agree well with the available experimental data. With the increase of\npressure, molecular dissociation is observed. Electron spin polarization\ndetermines the electronic structure of the system under low pressure, while it\nis suppressed around 30 $\\sim$ 50 GPa. Particularly, nonmetal-metal transition\nis taken into account, which also occurs at about 30 $\\sim$ 50 GPa. In\naddition, the optical properties of shock compressed oxygen are also discussed.",
        "positive": "Exotic rare earth-based materials for emerging spintronic technology: The progress in materials science has always been associated with the\ndevelopment of functional materials systems, which enables us to design\nproof-of-concept devices. To advance further, theoretical predictions of new\nnovel materials and their experimental realization is very important. This\nchapter reviews the intriguing properties of rare earth-based materials and\ntheir applications in spintronics. Spintronics is an emerging technology, which\nexploits spin degree of freedom of an electron along with its charge property.\nDiscovery of various physical phenomena and their industrial applications in\nthe field of magnetic sensors, magnetic recording and non-volatile memories\nsuch as magnetic random access memory (MRAM) and spin-transfer torque (STT)\nMRAM opens several new directions in this field. Materials with large spin\npolarization, strong spin-orbit coupling, and tunable electronic and magnetic\nproperties offer an excellent platform for the spintronics technology.\nCombination of rare earths with other elements such as transition metals show\nbroad range of structural, electronic, and magnetic properties which make them\nexcellent candidates for various spintronic applications. This chapter\ndiscusses many such materials ranging from Heusler alloys, topological\ninsulators to two-dimensional ferromagnets and their potential applications.\nThe review gives an insight of how rare-earth materials can play a key role in\nemerging future technology and have great potential in many new spintronic\nrelated applications."
    },
    {
        "anchor": "Gallium interstitial contributions to diffusion in gallium arsenide: Enthalpies of formation of gallium interstitials and all the other native\npoint defects in gallium arsenide are calculated using the same well-converged\n\\emph{ab initio} techniques. Using these results, equilibrium concentrations of\nthese defects are computed as a function of chemical potential from the arsenic\nrich limit to the gallium rich limit and as a function of the doping level from\n$p$-type to $n$-type. Gallium interstitial diffusion paths and migration\nbarriers for diffusion are determined for all the interstitial charge states\nwhich are favored for Fermi levels anywhere in the gap, and the charge states\nwhich dominate diffusion as a function of Fermi level are identified. The\neffects of chemical potential, doping level, and non-equilibrium defect\nconcentrations produced by ion implantation or irradiation on gallium\nself-diffusion are examined. Results are consistent with experimental results\nacross the ranges of doping and stoichometry where comparisons can be made.\nFinally, these calculations shed some light on the complex situation for\ngallium diffusion in gallium arsenide that is gallium-rich and doped heavily\n$p$-type.",
        "positive": "Magneto-transport in impurity-doped few-layer graphene spin valve: Using Keldysh nonequilibrium Green's function method we study the\nspin-dependent transport through impurity-doped few layer graphene sandwiched\nbetween two magnetic leads with an arbitrary mutual orientations of the\nmagnetizations. We find for parallel electrodes magnetizations that the\ndifferential conductance possesses two resonant peaks as the applied bias\nincreases. These peaks are traced back to a buildup of a magnetic moment on the\nimpurity due to the electrodes spin polarization. For a large mutual angle of\nthe electrodes magnetization directions, the two resonant peaks approach each\nothers and merge into a single peak for antiparallel orientation of the\nelectrodes magnetizations. We point out that the tunneling magnetoresistance\n(TMR) may change sign for relatively small changes in the values of the\npolarization parameters. Furthermore, we inspect the behaviour of the\ndifferential conductance and TMR upon varying the temperature."
    },
    {
        "anchor": "Computational Strategy for Graphene: Insight from Odd Electrons\n  Correlation: The correlation of odd electrons in graphene turns out to be significant so\nthat the species should be attributed to correlated ones. This finding\nprofoundly influences the computational strategy addressing it to\nmultireference computational schemes. Owing to serious problems related to the\nschemes realization, a compromise can be suggested by using single-determinant\napproaches based on either Hartree-Fock or Density-Functional theory in the\nform of unrestricted open-shell presentation. Both computational schemes enable\nto fix the electron correlation, while only the Hartree-Fock theory suggests a\nset of quantities to be calculated that can quantitatively characterize the\nelectron correlation and be used for a quantitative description of such\ngraphene properties as magnetism, chemical reactivity, and mechanical response.\nThe paper presents concepts and algorithms of the unrestricted Hartree-Fock\ntheory applied for the consideration of magnetic properties of nanographenes,\ntheir chemical modification by the example of stepwise hydrogenation, as well\nas a possible governing the electron correlation by the carbon skeleton\ndeformation.",
        "positive": "Oxygen vacancy driven mobility enhancement in epitaxial La-doped BaSnO3\n  from vacuum annealing: Wide bandgap (~3.1 eV) La-doped BaSnO3 (LBSO) has attracted increasing\nattention as one of the transparent oxide semiconductors since its bulk single\ncrystal shows a high carrier mobility (~320 cm2 V-1 s-1) with a high carrier\nconcentration (~10^20 cm-3). For this reason, many researchers have fabricated\nLBSO epitaxial films thus far, but the obtainable carrier mobility is\nsubstantially low compared to that of single crystals due to the formation of\nthe lattice/structural defects. Here we report that the mobility suppression in\nLBSO films can be lifted by a simple vacuum annealing process. The vacuum\nannealing of the LBSO films on MgO substrate increased the carrier\nconcentrations due to the oxygen vacancy formation, which leads to simultaneous\nlateral grain growth. As a result, the carrier mobility was greatly improved by\nthe vacuum annealing, which does not occur after heat treatment in air. These\nresults expand our current knowledge on the point defect formation in epitaxial\nLBSO films and show that vacuum annealing is a powerful tool for enhancing the\nmobility values of LBSO films."
    },
    {
        "anchor": "h-BN layer induced chiral decomposition in the electronic properties of\n  multilayer graphene: We discuss the chiral decomposition of non-symmetric stacking structures. It\nis shown that the low-energy electronic structure of Bernal stacked graphene\nmultilayer deposited on h-BN consists of chiral pseudospin doublets. N-layer\ngraphene stocks on h-BN layer have N/2 effective bilayer graphene systems and\none effective h-BN layer if N is even or (N-1)/2 effective graphene bilayers\nplus one graphene monolayer modified by h-BN layer if N is odd. We present the\ndecomposition procedure and we derive the recurrence relations for the\neffective parameters characterizing the chiral subsystems. The effective\nparameters consist in this case of the interlayer couplings and on-site\npotentials in contrast to pure graphene multilayer systems where only\ninterlayer couplings are modified. We apply this procedure to discuss the Klein\ntunneling phenomena and compare quantitatively the results with pure graphene\nmultilayer systems.",
        "positive": "Effect of Halide Composition on the Photochemical Stability of\n  Perovskite Photovoltaic Materials: Photochemical stability of encapsulated films of mixed halide perovskites\nwith a range of MAPb(I1-xBrx)3 compositions (solid solutions) was investigated\nunder accelerated stressing using concentrated sunlight. Evolution of light\nabsorption and the corresponding structural modifications in the films were\nrecorded by UV-vis spectroscopy and X-ray diffraction (XRD), respectively.\nMAPbBr3 film exhibited no degradation. In MAPbI3 and mixed halide\nMAPb(I1-xBrx)3 films, decomposition of the perovskite material with\ncrystallization of inorganic PbI2, and the corresponding degradation of light\nabsorption, were recorded. Introduction of bromine into the solid solution was\nfound to stress its structure and accelerate the degradation. The relevance of\naccelerated testing to standard operational conditions of solar cells was\nconfirmed by comparison to degradation experiments under outdoor sunlight\nexposure. Reasons for the reduced stability of the mixed halide compositions\nare discussed."
    },
    {
        "anchor": "Accurate prediction of the properties of materials using the CAM-B3LYP\n  Density Functional: Density functionals with asymptotic corrections to the long-range potential\nprovide entry-level methods for calculations on molecules that can sustain\ncharge transfer, but similar applications in Materials Science are rare. We\ndescribe an implementation of the CAM-B3LYP range-separated functional within\nthe Vienna Ab-initio Simulation Package (VASP) framework, together with its\nanalytical functional derivatives. Results obtained for eight representative\nmaterials: aluminum, diamond, graphene, silicon, NaCl, MgO, 2D h-BN and 3D\nh-BN, indicate that CAM-B3LYP predictions embody mean-absolute deviations (MAD)\ncompared to HSE06 that are reduced by a factor of 6 for lattice parameters, 4\nfor quasiparticle band gaps, 3 for the lowest optical excitation energies, and\n6 for exciton binding energies. Further, CAM-B3LYP appears competitive compared\nto ab initio G0W0 and Bethe-Salpeter equation (BSE) approaches. The CAM-B3LYP\nimplementation in VASP was verified by comparison of optimized geometries and\nreaction energies for isolated molecules taken from the ACCDB database,\nevaluated in large periodic unit cells, to analogous results obtained using\nGaussian basis sets. Using standard GW pseudopotentials and energy cutoffs for\nthe plane-wave calculations and the aug-cc-pV5Z basis set for the atomic-basis\nones, the MAD in energy for 1738 chemical reactions was 0.34 kcal mol-1, whilst\nfor 480 unique bond lengths this was 0.0036 {\\AA}; these values reduced to 0.28\nkcal mol-1 (largest error 0.94 kcal mol-1) and 0.0009 {\\AA} by increasing the\nplane-wave cuttoff energy to 850 eV.",
        "positive": "Prediction of pressure-induced stabilization of noble-gas-atom compounds\n  with alkali oxides and alkali sulfides: The cubic antifluorite structure comprises a face-centered cubic sublattice\nof anions with cations on the tetrahedral sites. The voids in the antifluorite\nstructure that are crucial for superionicity in Li2O might also act as atomic\ntraps. Trapping of guest atoms and small molecules within voids of a host\nstructure leads to the formation of what are known as clathrate compounds. Here\nwe investigate the possibility of trapping helium or larger neon guest atoms\nunder pressure within alkali metal oxide and sulfide structures. We find stable\nhelium and neon-bearing compounds at very low pressures. These structures are\nstabilized by a reduction in volume from incorporation of helium or neon atoms\nwithin the antifluorite structure. We predict that NeCs2S could be stable at\nambient pressure. Our study suggests a novel class of alkali oxide and sulfide\nmaterials incorporating noble gas atoms that might potentially be useful for\ngas storage."
    },
    {
        "anchor": "Auto-oscillation threshold, narrow spectral lines, and line jitter in\n  spin-torque oscillators based on MgO magnetic tunnel junctions: We demonstrate spin torque induced auto-oscillation in MgO-based magnetic\ntunnel junctions. At the generation threshold, we observe a strong line\nnarrowing down to 6 MHz at 300K and a dramatic increase in oscillator power,\nyielding spectrally pure oscillations free of flicker noise. Setting the\nsynthetic antiferromagnet into autooscillation requires the same current\npolarity as the one needed to switch the free layer magnetization. The induced\nauto-oscillations are observed even at zero applied field, which is believed to\nbe the acoustic mode of the synthetic antiferromagnet. While the phase\ncoherence of the auto-oscillation is of the order of microseconds, the power\nautocorrelation time is of the order of milliseconds and can be strongly\ninfluenced by the free layer dynamics.",
        "positive": "Dynamical theory of angle-resolved electron energy loss and gain\n  spectroscopies of phonons and magnons including multiple scattering effects: We present a method for computing angle-resolved electron-energy-loss and\ngain spectroscopies for phonon and magnon excitations in transmission electron\nmicroscopy. Fractional scattering intensities are derived from the\ntemperature-dependent time auto-correlation of the electron beam wave function.\nThis method captures both single and multiple scattering processes, as well as\ndynamical diffraction effects. Our method remains computationally efficient,\nand it is easy to parallelize."
    },
    {
        "anchor": "Control of molecular orbital ordering using a van der Waals monolayer\n  ferroelectric: Two-dimensional (2D) ferroelectric materials provide a promising platform for\nthe electrical control of quantum states. In particular, due to their 2D\nnature, they are suitable for influencing the quantum states of deposited\nmolecules via the proximity effect. Here, we report electrically controllable\nmolecular states in phthalocyanine molecules adsorbed on monolayer\nferroelectric material SnTe. In particular, we demonstrate that the strain and\nferroelectric order in SnTe creates a transition between two distinct orbital\norders in the adsorbed phthalocyanine molecules. By controlling the\npolarization of the ferroelectric domain using scanning tunneling microscopy\n(STM), we have successfully demonstrated that orbital order can be manipulated\nelectrically. Our results show how ferroelastic coupling in 2D systems allows\ncontrol of molecular states, providing a starting point for ferroelectrically\nswitchable molecular orbital ordering and ultimately, electrical control of\nmolecular magnetism.",
        "positive": "First-principles pressure dependent investigation of the physical\n  properties of KB2H8: a prospective high-TC superconductor: Using the density functional theory (DFT) based first-principles\ninvestigation, the structural, mechanical, hardness, elastic anisotropy,\noptoelectronic, and thermal properties of cubic KB2H8 have been studied within\nthe uniform pressure range of 0 - 24 GPa. The calculated structural parameters\nare in good agreement with the previous theoretical work. The compound KB2H8 is\nfound to be structurally and thermodynamically stable in the pressure range\nfrom 8 GPa to 24 GPa. Single crystal elastic constants Cij and bulk elastic\nmoduli (B, G and Y) increase systematically with pressure from 8 GPa to 24 GPa.\nIn the stable phase, KB2H8 is moderately elastically anisotropic and ductile in\nnature. The compound is highly machinable and fracture resistant. The Debye\ntemperature, melting temperature and thermal conductivity increases with\npressure. The results of electronic band structure calculations and optical\nparameters at different pressures are consistent with each other. The compound\nis optically isotropic. The compound KB2H8 has potential to be used as a very\nefficient solar energy reflector. The electronic energy density of states at\nthe Fermi level decreases systematically with increasing pressure. The same\ntrend is found for the repulsive Coulomb pseudopotential. Possible relevance of\nthe studied properties to superconductivity has also been discussed in this\npaper."
    },
    {
        "anchor": "Clifford Boundary Conditions for Periodic Systems: the Madelung Constant\n  of Cubic Crystals in 1, 2 and 3 Dimensions: In this work we demonstrate the robustness of a real-space approach for the\ntreatment of infinite systems described with periodic boundary conditions that\nwe have recently proposed [J. Phys. Chem. Lett. 17, 7090]. In our approach we\nextract a fragment, i.e., a supercell, out of the infinite system, and then\nmodifying its topology into the that of a Clifford torus which is a flat,\nfinite and border-less manifold. We then renormalize the distance between two\npoints by defining it as the Euclidean distance in the embedding space of the\nClifford torus. With our method we have been able to calculate the reference\nresults available in the literature with a remarkable accuracy, and at a very\nlow computational effort. In this work we show that our approach is robust with\nrespect to the shape of the supercell. In particular, we show that the Madelung\nconstants converge to the same values but that the convergence properties are\ndifferent. Our approach scales linearly with the number of atoms. The\ncalculation of Madelung constants only takes a few seconds on a laptop computer\nfor a relative precision of about 10$^{-6}$.",
        "positive": "The electronic structure of the antiferromagnetic semiconductor\n  MnSb_2S_4: The electronic band structures of orthorhombic (oP28) and monoclinic (mC28)\nMnSb_2S_4 were investigated with ab initio calculations in the local spin\ndensity approximation (LSDA) to the density functional theory (DFT). An\nanalysis of the electronic properties and of the chemical bonding is provided\nusing the augmented spherical wave (ASW) method considering nonmagnetic,\nferromagnetic, ferrimagnetic and antiferromagnetic model orderings. In\nagreement with experimental results both modifications of MnSb_2S_4 are\npredicted to be antiferromagnetic. While the experimental band gap is missed\nfor the monoclinic polymorph, the calculated band gap for orthorhombic\nMnSb_2S_4 is close to the experimental one."
    },
    {
        "anchor": "Doping and Defect-Induced Germanene: A Superior Media for Sensing H2S,\n  SO2, and CO2 gas molecules: First-principles calculations based on density functional theory (DFT) have\nbeen employed to investigate the structural, electronic, and gas-sensing\nproperties of pure, defected, and doped germanene nanosheets. Our calculations\nhave revealed that while a pristine germanene nanosheet adsorbs CO2 weakly, H2S\nmoderately, and SO2 strongly, the introduction of vacancy defects increases the\nsensitivity significantly which is promising for future gas-sensing\napplications.Mulliken population analysis imparts that an appreciable amount of\ncharge transfer occurs between gas molecules and a germanene nanosheet which\nsupports our results for adsorption energies of the systems. The enhancement of\nthe interactions between gas molecules and the germanene nanosheet has been\nfurther investigated by density of states.Projected density of states provides\ndetailed insight of the gas molecules contribution in the gas-sensing\nsystem.Additionally, the influences of substituted dopant atoms such as B, N,\nand Al in the germanene nanosheet have also been considered to study the impact\non its gas sensing ability. There was no significant improvement found in doped\ngas sensing capability of germanene over the vacancy defects, except for CO2\nupon adsorption on N-doped germanene.",
        "positive": "Double-layer ice from first principles: The formation of monolayer and multilayer ice with a square lattice structure\nhas recently been reported on the basis of transmission electron microscopy\nexperiments, renewing interest in confined two dimensional ice. Here we report\na systematic density functional theory study of double-layer ice in\nnano-confinement. A phase diagram as a function of confinement width and\nlateral pressure is presented. Included in the phase diagram are honeycomb\nhexagonal, square-tube, hexagonal-close-packed and buckled-rhombic structures.\nHowever, contrary to experimental observations, square structures do not\nfeature: our most stable double-layer square structure is predicted to be\nmetastable. This study provides general insight into the phase transitions of\ndouble-layer confined ice and a fresh theoretical perspective on the stability\nof square ice in graphene nanocapillary experiments."
    },
    {
        "anchor": "Understanding the Effect of Uniaxial Tensile Strain on the Early Stages\n  of Sensitization in AISI 304 Austenitic Stainless Steel: In the present study, an attempt has been made to understand the effect of\ndifferent competing mechanisms controlling the overall degree of sensitization\n(DOS) of deformed austenitic stainless steel at the early stage of\nsensitization. The Double Loop Electrochemical Potentiokinetic Reactivation\n(DL-EPR) studies were performed to characterize the Degree of Sensitization\n(DOS) as functions of pre-defined strain and sensitization temperature. X-ray\nDiffraction (XRD) and Scanning Electron Microscopy (SEM) were used to explain\nthe phenomena qualitatively. A non monotonous behaviour in the variation of DOS\nhas been observed with deformation and sensitization temperature. The presence\nof Deformation Induced Martensites (DIM) and their transformation into tempered\nmartensites (alpha + Fe3C) at higher temperatures was found to play major roles\nin controlling the overall sensitization and desensitization processes.",
        "positive": "Tailoring Materials for Mottronics: Excess Oxygen Doping of a\n  Prototypical Mott Insulator: The Mott transistor is a paradigm for a new class of electronic\ndevices---often referred to by the term Mottronics---, which are based on\ncharge correlations between the electrons. Since correlation-induced insulating\nphases of most oxide compounds are usually very robust, new methods have to be\ndeveloped to push such materials right to the boundary to the metallic phase in\norder to enable the metal-insulator transition to be switched by electric\ngating.\n  Here we demonstrate that thin films of the prototypical Mott insulator\nLaTiO$_3$ grown by pulsed laser deposition under oxygen atmosphere are readily\ntuned by excess oxygen doping across the line of the band-filling controlled\nMott transition in the electronic phase diagram. The detected insulator to\nmetal transition is characterized by a strong change in resistivity of several\norders of magnitude. The use of suitable substrates and capping layers to\ninhibit oxygen diffusion facilitates full control of the oxygen content and\nrenders the films stable against exposure to ambient conditions, making\nLaTiO$_{3+x}$ a promising functional material for Mottronics devices."
    },
    {
        "anchor": "Intra-unitcell cluster-cluster magnetic compensation and large exchange\n  bias in cubic alloys: Composite quantum materials are the ideal examples of multifunctional systems\nwhich simultaneously host more than one novel quantum phenomenon in physics.\nHere, we present a combined theoretical and experimental study to demonstrate\nthe presence of an extremely large exchange bias in the range 0.8 T - 2.7 T and\na fully compensated magnetic state (FCF) in a special type of Pt and Ni doped\nMn$_3$In cubic alloy. Here, oppositely aligned uncompensated moments in two\ndifferent atomic clusters sum up to zero which are responsible for the FCF\nstate. Our Density functional theory (DFT) calculations show the existence of\nseveral possible ferrimagnetic configurations with the FCF as the energetically\nmost stable one. The microscopic origin of the large exchange bias can be\ninterpreted in terms of the exchange interaction between the FCF background and\nthe uncompensated ferrimagnetic clusters stabilized due to its negligible\nenergy difference with respect to the FCF phase. We utilize pulsed magnetic\nfield up to 60 T and 30 T static field magnetization measurements to confirm\nthe intrinsic nature of exchange bias in our system. Finally, our Hall effect\nmeasurements demonstrate the importance of uncompensated noncoplanar\ninterfacial moments for the realization of large EB. The present finding of\ngigantic exchange bias in a unique compensated ferrimagnetic system opens up a\ndirection for the design of novel quantum phenomena for the technological\napplications.",
        "positive": "Physics-based Constitutive Modeling of Photo-oxidative Aging in\n  Semi-Crystalline Polymers based on Chemical Characterization Techniques: This paper proposes a physio-chemically-based constitutive framework to\nsimulate and predict the response of semi-crystalline low-density polyethylene\n(LDPE) to severe photo-oxidation. Photo-oxidation induced by exposure to\nUltra-Violet (UV) light and oxygen is the dominant degradation mechanism\naffecting the lifespan of LDPE. In this work, we propose evolution functions\nfor the material properties in the constitutive equations of\n\\cite{boyce2000constitutive} to incorporate the effects of photo-oxidation on\nthe mechanical response of LDPE. The evolution functions are based on\nchemically verified processes that are responsible for material degradation,\nnamely the change in crystallinity and mass loss relative to the initial\npristine films over exposure time. Changes in crystallinity and mass loss are\ncharacterized by Differential Scanning Calorimetry (DSC) and Quartz Crystal\nMicrobalance with Dissipation Monitoring (QCM-D) experiments, respectively.\nConnecting the physio-chemical processes affecting polymer network evolution to\nthe mechanical response of LDPE bypasses the need for defining fitting\nparameters that carry no physical meaning. The developed constitutive framework\nis validated with respect to a series of in-house uniaxial tensile tests\nperformed on LDPE aged for different UV exposure times. Comparison of the\nconstitutive framework versus experimental mechanical tests also confirms the\naccuracy of DSC and QCM-D as rigorous techniques to monitor and characterize\ndegradation in LDPE films. The outcome shed light on the evolution of the\nmacromolecular network in LDPE under extreme photo-oxidation and the evolution\nof the associated mechanical material properties."
    },
    {
        "anchor": "Proximity-induced magnetism in transition-metal substituted graphene: We investigate the interactions between two identical magnetic impurities\nsubstituted into a graphene superlattice. Using a first-principles approach, we\ncalculate the electronic and magnetic properties for transition-metal\nsubstituted graphene systems with varying spatial separation. These\ncalculations are compared for three different magnetic impurities, manganese,\nchromium, and vanadium. We determine the electronic band structure, density of\nstates, and Millikan populations (magnetic moment) for each atom, as well as\ncalculate the exchange parameter between the two magnetic atoms as a function\nof spatial separation. We find that the presence of magnetic impurities\nestablishes a distinct magnetic moment in the graphene lattice, where the\ninteractions are highly dependent on the spatial and magnetic characteristic\nbetween the magnetic atoms and the carbon atoms, which leads to either\nferromagnetic or antiferromagnetic behavior. Furthermore, through an analysis\nof the calculated exchange energies and partial density of states, it is\ndetermined that interactions between the magnetic atoms can be classified as an\nRKKY interaction.",
        "positive": "Terahertz emitters and detectors based on carbon nanotubes: We formulate and justify several proposals utilizing the unique electronic\nproperties of different types of carbon nanotubes for a broad range of\napplications to THz optoelectronics, including THz generation by hot electrons\nin quasi-metallic nanotubes, frequency multiplication in chiral-nanotube-based\nsuperlattices controlled by a transverse electric field, and THz radiation\ndetection and emission by armchair nanotubes in a strong magnetic field."
    },
    {
        "anchor": "Irradiation-induced Ag nanocluster nucleation in silicate glasses:\n  analogy with photography: The synthesis of Ag nanoclusters in sodalime silicate glasses and silica was\nstudied by optical absorption (OA) and electron spin resonance (ESR)\nexperiments under both low (gamma-ray) and high (MeV ion) deposited energy\ndensity irradiation conditions. Both types of irradiation create electrons and\nholes whose density and thermal evolution - notably via their interaction with\ndefects - are shown to determine the clustering and growth rates of Ag\nnanocrystals. We thus establish the influence of redox interactions of defects\nand silver (poly)ions. The mechanisms are similar to the latent image formation\nin photography: irradiation-induced photoelectrons are trapped within the glass\nmatrix, notably on dissolved noble metal ions and defects, which are thus\nneutralized (reverse oxidation reactions are also shown to exist). Annealing\npromotes metal atom diffusion, which in turn leads to cluster nuclei formation.\nThe cluster density depends not only on the irradiation fluence, but also - and\nprimarily - on the density of deposited energy and the redox properties of the\nglass. Ion irradiation (i.e., large deposited energy density) is far more\neffective in cluster formation, despite its lower neutralization efficiency\n(from Ag+ to Ag0) as compared to gamma photon irradiation.",
        "positive": "The Hot-Spot Phenomenon and its Countermeasures in Bipolar Power\n  Transistors by Analytical Electro-Thermal Simulation: This communication deals with a theoretical study of the hot spot onset (HSO)\nin cellular bipolar power transistors. This well-known phenomenon consists of a\ncurrent crowding within few cells occurring for high power conditions, which\nsignificantly decreases the forward safe operating area (FSOA) of the device.\nThe study was performed on a virtual sample by means of a fast, fully\nanalytical electro-thermal simulator operating in the steady state regime and\nunder the condition of imposed input base current. The purpose was to study the\ndependence of the phenomenon on several thermal and geometrical factors and to\ntest suitable countermeasures able to impinge this phenomenon at higher biases\nor to completely eliminate it. The power threshold of HSO and its localization\nwithin the silicon die were observed as a function of the electrical bias\nconditions as for instance the collector voltage, the equivalent thermal\nresistance of the assembling structure underlying the silicon die, the value of\nthe ballasting resistances purposely added in the emitter metal\ninterconnections and the thickness of the copper heat spreader placed on the\ndie top just to the aim of making more uniform the temperature of the silicon\nsurface."
    },
    {
        "anchor": "Multiferroic phase transition near room temperature in BiFeO3 films: In multiferroic BiFeO3 thin films grown on highly mismatched LaAlO3\nsubstrates, we reveal the coexistence of two differently distorted polymorphs\nthat leads to striking features in the temperature dependence of the structural\nand multiferroic properties. Notably, the highly distorted phase\nquasi-concomitantly presents an abrupt structural change, transforms from a\nhard to a soft ferroelectric and transitions from antiferromagnetic to\nparamagnetic at 360+/-20 K. These coupled ferroic transitions just above room\ntemperature hold promises of giant piezoelectric, magnetoelectric and\npiezomagnetic responses, with potential in many applications fields.",
        "positive": "Constrained Monte Carlo Method and Calculation of the Temperature\n  Dependence of Magnetic Anisotropy: We introduce a constrained Monte Carlo method which allows us to traverse the\nphase space of a classical spin system while fixing the magnetization\ndirection. Subsequently we show the method's capability to model the\ntemperature dependence of magnetic anisotropy, and for bulk uniaxial and cubic\nanisotropies we recover the low-temperature Callen-Callen power laws in M. We\nalso calculate the temperature scaling of the 2-ion anisotropy in L10 FePt, and\nrecover the experimentally observed M^2.1 scaling. The method is newly applied\nto evaluate the temperature dependent effective anisotropy in the presence of\nthe N'eel surface anisotropy in thin films with different easy axis\nconfigurations. In systems having different surface and bulk easy axes, we show\nthe capability to model the temperature-induced reorientation transition. The\nintrinsic surface anisotropy is found to follow a linear temperature behavior\nin a large range of temperatures."
    },
    {
        "anchor": "Stability of 71\u00b0 stripe domains in epitaxial BiFeO3 films upon\n  repeated electrical switching: The 71{\\deg} stripe domain patterns of epitaxial BiFeO3 thin films are\nfrequently being explored to achieve new functional properties, dissimilar from\nthe BiFeO3 bulk properties. We show that in-plane switching and out-of-plane\nswitching of these domains behave very differently. In the in-plane\nconfiguration the domains are very stable, whereas in the out-of-plane\nconfiguration the domains change their size and patterns, depending on the\napplied switching voltage frequency. This paper has been published in Phys.\nStatus Solidi B (http://dx.doi.org/10.1002/pssb.201248329)",
        "positive": "Control of octahedral rotations in (LaNiO$_3$)$_{n}$/(SrMnO$_3$)$_m$\n  superlattices: Oxygen octahedral rotations have been measured in short-period\n(LaNiO$_3$)$_n$/(SrMnO$_3$)$_m$ superlattices using synchrotron diffraction.\nThe in-plane and out-of-plane bond angles and lengths are found to\nsystematically vary with superlattice composition. Rotations are suppressed in\nstructures with $m>n$, producing a nearly cubic form of LaNiO$_3$. Large\nrotations are present in structures with $m<n$, leading to reduced bond angles\nin SrMnO$_3$. The metal-oxygen-metal bond lengths decrease as rotations are\nreduced, in contrast to behavior previously observed in strained, single layer\nfilms. This result demonstrates that superlattice structures can be used to\nstabilize non-equilibrium octahedral behavior in a manner distinct from\nepitaxial strain, providing a novel means to engineer the electronic and\nferroic properties of oxide heterostructures."
    },
    {
        "anchor": "Native point defects from stoichiometry-linked chemical potentials in\n  cubic boron arsenide: The presence of a point defect typically breaks the stoichiometry in a\nsemiconductor. For example, a vacancy on an A-site in an AB compound makes the\ncrystal B-rich. As the stoichiometry changes, so do the chemical potentials.\nWhile the prevalent first-principles methods have provided significant insight\ninto characters of point defects in a transparent manner, the crucial\nconnection between crystal stoichiometry and chemical potentials is usually not\nmade. However, ad hoc choices for chemical potentials can lead to nonphysical\nnegative formation energies in some Fermi level ranges, along with questions\nabout charge balance. Herein, we formulate a canonical framework describing how\nthe chemical potential of each element is directly linked to the composition of\nthe crystal under (off-)stoichiometric conditions instead of the ad hoc\nassumption that the chemical potential is the elemental limit under a certain\ngrowth condition. Consequently, the chemical potential changes with the Fermi\nlevel within the band gap, and the formation energies are positive. Using such\nan approach, we present $ab$ $initio$ results for native point defects in BAs,\na semiconductor with ultra-high room temperature thermal conductivity. We find\nthat antisites are the constitutional defects in off-stoichiometric material,\nwhile B$_\\mathrm{As}$ antisites and B vacancies dominate in the stoichiometric\nmaterial. We further discuss the thermodynamic equilibrium and charge\nneutrality point in BAs in light of our stoichiometry-determined chemical\npotentials. As discussed, our work offers a more applicable and accessible\napproach to tackle defect formation energies in semiconductors, especially the\nones with wide gap where negative formation energies are commonly seen.",
        "positive": "Prediction of low energy phase transition in metal doped MoTe$_2$ from\n  first principle calculations: Metal-insulator transitions in two dimensional materials represent a great\nopportunity for fast, low energy and ultra-dense switching devices. Due to the\nsmall energy difference between its semimetallic and semiconducting crystal\nphases, phase transition in MoTe$_2$ can occur with an unprecedented small\namount of external perturbations. In this work, we used density functional\ntheory to predict critical strain and electrostatic voltage required to control\nthe phase transition of 3d and 4d metal doped MoTe$_2$. We found that small\ndoping contents dramatically affect the relative energies of MoTe$_2$ crystal\nphases and can largely reduced the energy input to trigger the transition,\ncompared to pristine case. Moreover, the kinetics corresponding to the phase\ntransition in the proposed doped materials are several order of magnitude\nfaster than in MoTe$_2$. For example, we predict 6.3 \\% Mn doped MoTe$_2$ to\nswitch phase under 1.19 V gate voltage in less than 1 $\\mu$s with an input\nenergy of 0.048 aJ/nm$^3$. Due to the presence of dopant, the controlled change\nof phase is often complemented with a change in magnetic moment leading to\nmulti-functional phase transition."
    },
    {
        "anchor": "Negative linear compressibility and unusual dynamic behaviors of NaB3: First-principles calculations reveal that sodium boride (NaB3) undergoes a\nphase transition from a tetragonal P4/mbm phase to an orthorhombic Pbam phase\nat about 16 GPa, accompanied by counterintuitive lattice expansion along the\ncrystallographic a-axis. This unusual compression behavior is identified as\nnegative linear compressibility (NLC), which is dominantly attributed to the\nsymmetry-breaking of boron framework. Meanwhile, the P4/mbm and Pbam phases\nform superionic conductors after undergoing a peculiar swap state at high\ntemperature. Specifically, under warm conditions the Na cation pairs exhibit a\nrare local exchange (or rotation) behavior, which may be originated from the\nasymmetric energy barriers of different diffusion paths. The study of NaB3\ncompound sheds new light on a material with the combination of NLC and ion\ntransportation at extreme conditions.",
        "positive": "Influence of crystal structure on charge carrier effective masses in\n  BiFeO$_3$: Ferroelectric-based photovoltaics have shown great promise as a source of\nrenewable energy, thanks to their in-built charge separation capability, yet\ntheir efficiency is often limited by low charge carrier mobilities. In this\nwork, we compare the photovoltaic prospects of various phases of the\nmultiferroic material BiFeO$_3$ by evaluating their charge carrier effective\nmasses using first-principles simulations. We identify a tetragonal phase with\nthe promising combination of a large spontaneous polarisation and relatively\nlight charge carriers. From a systematic study of the octahedral distortions\npresent in BiFeO$_3$, we explain the relationship between structure and\neffective masses in terms of the changes to the orbital character and overlap\nat the band edges that result from changes in the geometry. The findings in\nthis study provide some design principles to engineer desired effective masses\nin BiFeO$_3$ and similar materials through manipulation of their crystal\nstructures in experimentally accessible ways."
    },
    {
        "anchor": "Atomic-scale investigation of $\u03b3$-Ga$_2$O$_3$ deposited on\n  MgAl$_2$O$_4$ and its relationship with $\u03b2$-Ga$_2$O$_3$: Nominally phase-pure $\\gamma$-$Ga_2O_3$ was deposited on (100) $MgAl_2O_4$\nwithin a narrow temperature window centered at $\\sim$470 $^{\\circ}$C using\nmetal-organic chemical vapor deposition (MOCVD). The film deposited at 440\n$^{\\circ}$C exhibited either poor crystallization or an amorphous structure;\nthe film grown at 500 $^{\\circ}$C contained both $\\beta$-$Ga_2O_3$ and\n$\\gamma$-$Ga_2O_3$. A nominally phase-pure $\\beta$-$Ga_2O_3$ film was obtained\nat 530 $^{\\circ}$C. Atomic-resolution scanning transmission electron microscopy\n(STEM) investigations of the $\\gamma$-$Ga_2O_3$ film grown at 470 $^{\\circ}$C\nrevealed a high density of antiphase boundaries. A planar defect model\ndeveloped for $\\gamma$-$Al_2O_3$ was extended to explain the stacking sequences\nof the Ga sublattice observed in the STEM images of $\\gamma$-$Ga_2O_3$. The\npresence of the 180$^{\\circ}$ rotational domains and 90$^{\\circ}$ rotational\ndomains of $\\beta$-$Ga_2O_3$ inclusions within the $\\gamma$-$Ga_2O_3$ matrix is\ndiscussed within the context of a comprehensive investigation of the epitaxial\nrelationship between those two phases in the as-grown film at 470 $^{\\circ}$C\nand the same film annealed at 600 $^{\\circ}$C. The results led to the\nhypotheses that (i) incorporation of certain dopants including Si, Ge, Sn, Mg,\nAl, and Sc, into $\\beta$-$Ga_2O_3$, locally stabilizes the \"$\\gamma$-phase\" and\n(ii) the site preference(s) for these dopants promotes the formation of the\n\"$\\gamma$-phase\" and/or $\\gamma$-$Ga_2O_3$ solid solutions. However, in the\nabsence of such dopants, pure $\\gamma$-$Ga_2O_3$ remains the least stable\n$Ga_2O_3$ polymorph, as indicated by its very narrow growth window, lower\ngrowth temperatures relative to other $Ga_2O_3$ polymorphs, and the largest\ncalculated difference in Helmholtz free energy per formula unit between\n$\\gamma$-$Ga_2O_3$ and $\\beta$-$Ga_2O_3$ than all other polymorphs.",
        "positive": "Spatially-Resolved Band Gap and Dielectric Function in 2D Materials from\n  Electron Energy Loss Spectroscopy: The electronic properties of two-dimensional (2D) materials depend\nsensitively on the underlying atomic arrangement down to the monolayer level.\nHere we present a novel strategy for the determination of the band gap and\ncomplex dielectric function in 2D materials achieving a spatial resolution down\nto a few nanometers. This approach is based on machine learning techniques\ndeveloped in particle physics and makes possible the automated processing and\ninterpretation of spectral images from electron energy-loss spectroscopy\n(EELS). Individual spectra are classified as a function of the thickness with\n$K$-means clustering and then used to train a deep-learning model of the\nzero-loss peak background. As a proof-of-concept we assess the band gap and\ndielectric function of InSe flakes and polytypic WS$_2$ nanoflowers, and\ncorrelate these electrical properties with the local thickness. Our flexible\napproach is generalizable to other nanostructured materials and to\nhigher-dimensional spectroscopies, and is made available as a new release of\nthe open-source EELSfitter framework."
    },
    {
        "anchor": "Spatial conductivity mapping of unprotected and capped black phosphorus\n  using microwave microscopy: Thin layers of black phosphorus present an ideal combination of a 2D material\nwith a tunable direct bandgap and high carrier mobility. However the material\nsuffers from degradation in ambient conditions due to an oxidation reaction\nwhich involves water, oxygen and light. We have measured the spatial profile of\nthe conductivity on flakes of black phosphorus as a function of time using\nscanning microwave impedance microscopy. A microwave excitation (3 GHz) allows\nto image a conducting sample even when covered with a dielectric layer. We\nobserve that on bare black phosphorus, the conductivity changes drastically\nover the whole surface within a day. We demonstrate that the degradation\nprocess is slowed down considerably by covering the material with a 10 nm layer\nof hafnium oxide. It is stable for more than a week, opening up a route towards\nstable black phosphorus devices in which the high dielectric constant of\nhafnium oxide can be exploited. Covering black phosphorus with a 15 nm boron\nnitride flake changes the degradation process qualitatively, it is dominated by\nthe edges of the flake indicating a diffusive process and happens on the scale\nof days.",
        "positive": "Novel Magnetic Quantization of Bismuthene: The generalized tight-binding model, being based on the spin-dependent\nsublattices, is developed to explore the magnetic quantization of monolayer\nbismuthene. The sp$^{3}$ orbital hybridizations, site energies, nearest and\nnext-nearest hopping integrals, spin-orbital interactions and magnetic field\n(${B_{z}}$ ${\\hat{z}}$) are taken into account simultaneously. There exist\nthree groups of low-lying Landau levels (LLs), in which they are mainly from\nthe (6p$_{x}$,6p$_{y}$,6p$_{z}$) orbitals, and only the first group belongs to\nthe unoccupied conduction states. Furthermore, each group is further split into\nthe spin-up- and spin-down-dominated subgroups. The six subgroups present the\nrich and unique $B_{z}$-dependent LL energy spectra, covering the specific or\narc-shaped $% B_{z}$-dependences, the normal/irregular spin-split energies, and\nthe non-crossing/crossing/anti-crossing behaviors. Specially, the second group\nof valence LLs near the Fermi level can create the frequent inter-subgroup LL\nanti-crossings since the main and side modes are comparable. The main features\nof energy spectra can create the special structures in density of states."
    },
    {
        "anchor": "Semiconducting Black Phosphorus: Synthesis, Transport Properties and\n  Electronic Applications: Phosphorus is one of the most abundant elements preserved in earth,\nconstructing with a fraction of ~0.1% of the earth crust. In general,\nphosphorus has several allotropes. The two most commonly seen allotropes, white\nand red phosphorus, are widely used in explosives and safety matches. In\naddition, black phosphorus, though rarely mentioned, is a layered semiconductor\nand have great potentials in optical and electronic applications. Remarkably,\nthis layered material can be reduced to one single atomic layer in the vertical\ndirection owing to the van der Waals structure, known as phosphorene, where the\nphysical properties can be tremendously different from its bulk counterpart. In\nthis review article, we trace back to the 100 years research history on black\nphosphorus from the synthesis to material properties, and extend the topic from\nblack phosphorus to phosphorene. The physical and transport properties are\nhighlighted, aiming at further applications in electronic and optoelectronics\ndevices.",
        "positive": "Optical characterization of electron-phonon interactions at the saddle\n  point in graphene: The role of electron-phonon interactions is experimentally and theoretically\ninvestigated near the saddle point absorption peak of graphene. The\ndifferential optical transmission spectra of multiple, non-interacting layers\nof graphene reveals the dominant role played by electron-acoustic phonon\ncoupling in bandstructure renormalization. Using a Born approximation for\nelectron-phonon coupling and experimental estimates of the dynamic phonon\nlattice temperature, we deduce the effective acoustic deformation potential to\nbe $D^{\\rm ac}_{\\rm eff} \\simeq 5$eV. This value is in accord with recent\ntheoretical predictions but differs substantially from those obtained using\nelectrical transport measurements."
    },
    {
        "anchor": "All-Materials-Inclusive Flash Spark Plasma Sintering: A new flash (ultra-rapid) spark plasma sintering method applicable to various\nmaterials systems, regardless of their electrical resistivity, is developed. A\nnumber of powders ranging from metals to electrically insulative ceramics have\nbeen successfully densified resulting in homogeneous microstructures within\nsintering times of 8-35 s. A finite element simulation reveals that the\ndeveloped method, providing an extraordinary fast and homogeneous heating\nconcentrated in the sample's volume and punches, is applicable to all the\ndifferent samples tested. The utilized uniquely controllable flash phenomenon\nis enabled by the combination of the electric current concentration around the\nsample and the confinement of the heat generated in this area by the lateral\nthermal contact resistance. The presented new method allows: extending flash\nsintering to nearly all materials, controlling sample shape by an added\ngraphite die, and an energy efficient mass production of small and intermediate\nsize objects. This approach represents also a potential venue for future\ninvestigations of flash sintering of complex shapes.",
        "positive": "Highly Tunable Intrinsic Exchange Bias from Interfacial Reconstruction\n  in Epitaxial NixCoyFe3-x-yO4(111)/\u03b1-Al2O3(0001) Thin Films: Intrinsic exchange bias up to 12.6 kOe is observed in\nNixCoyFe3-x-yO4(111)/{\\alpha}-Al2O3(0001) (0<=x+y<=3) epitaxial thin films\nwhere 0.15<=y<=2. An interfacial layer of rock-salt structure emerges between\nNixCoyFe3-x-yO4 thin films and {\\alpha}-Al2O3 substrates and is proposed as the\nantiferromagnetic layer unidirectionally coupled with ferrimagnetic\nNixCoyFe3-x-yO4. In NiCo2O4(111)/{\\alpha}-Al2O3(0001) films, results of\nreflection high energy electron diffraction, X-ray photoelectron spectroscopy,\nX-ray reflectometry, and polarized neutron reflectometry support that the\ninterfacial layer is antiferromagnetic NixCo1-xO (0.32<=x<=0.49) of rock-salt\nstructure; the interfacial layer and exchange bias can be controlled by growth\noxygen pressure revealing the key role of oxygen in the mechanism of the\ninterfacial reconstruction. This work establishes a family of intrinsic\nexchange bias materials with great tunability by stoichiometry and growth\nparameters and emphasizes the strategy of interface engineering in controlling\nmaterial functionalities."
    },
    {
        "anchor": "Atomic-scale detection of magnetic impurity interactions in bulk\n  semiconductors: We demonstrate on the basis of ab initio simulations how passivated\nsemiconductor surfaces can be exploited to study bulklike interaction\nproperties and wave functions of magnetic impurities on the atomic scale with\nconventional and spin-polarized scanning tunneling microscopy. By applying our\napproach to the case of $3d$ transition metal impurities close to the\nH/Si$(111)$ surface, we show exemplarily that their wave functions in Si are\nless extended than for Mn in GaAs, thus obstructing ferromagnetism in Si.\nFinally, we discuss possible applications of this method to other dilute\nmagnetic semiconductors.",
        "positive": "Above-room-temperature ferromagnetism in half-metallic Heusler compounds\n  NiCrP, NiCrSe, NiCrTe and NiVAs: A first-principles study: We study the interatomic exchange interactions and Curie temperatures in\nhalf-metallic semi Heusler compounds NiCrZ (Z=P, Se, Te) and NiVAs. The study\nis performed within the framework of density functional theory. The calculation\nof exchange parameters is based on the frozen-magnon approach. It is shown that\nthe exchange interactions in NiCrZ vary strongly depending on the Z\nconstituent. The Curie temperature, Tc, is calculated within the mean field and\nrandom phase approximations. The difference between two estimations is related\nto the properties of the exchange interactions. The predicted Curie\ntemperatures of all four systems are considerably higher than room temperature.\nThe relation between the half-metallicity and the value of the Curie\ntemperature is discussed. The combination of a high spin-polarization of charge\ncarriers and a high Curie temperature makes these Heusler alloys interesting\ncandidates for spintronics applications."
    },
    {
        "anchor": "Quantum Interference Control of Carriers and Currents in Zincblende\n  Semiconductors based on Nonlinear Absorption Processes: Quantum interference between optical absorption processes can excite carriers\nwith a polarized distribution in the Brillouin zone depending on properties of\nthe incident optical fields. The polarized distribution of carriers introduces\na current that can be controlled by the phases and polarizations of the\nincident optical fields. Here we study the quantum interference of 2- and\n3-photon absorption processes in AlGaAs. We present theoretical predictions for\ncarrier and current injection rates considering different frequencies, phases,\nand polarizations of the incident fields. We also discuss the important\nfeatures that result from only nonlinear optical processes being involved,\nwhich leads for instance to a sharper distribution of carriers in the Brillouin\nzone.",
        "positive": "Temperature induced inversion of oxygen response in CVD graphene on SiO2: We have synthesized single-layer graphene on Cu foils using chemical vapor\ndeposition method and transferred the graphene to the top of a Si/SiO2\nsubstrate with a pair of prefabricated Ti/Au electrodes. A resistive\ngraphene-based gas sensor prepared in this way revealed n-type oxygen response\nat room temperature and we have successfully fitted the data obtained with\nvarying oxygen levels using a two-site Langmuir model. P-type oxygen response\nof our sensor was observed after the temperature was raised to 100 oC, with a\nreversible transition to n-type behaviour when the temperature was lowered back\nto room temperature. Such inversion of the gas response type with temperature\nwas interpreted as a result of interplay between the adsorbate-induced charge\ntransfer and charge carrier scattering. The transduction function was derived,\nwhich relates the electrical response to surface coverage through both the\ninduced mobility and charge density changes."
    },
    {
        "anchor": "Fully-Compensated Ferrimagnetic Spin Filter Materials within the\n  Cr$\\textit{M}\\textit{N}$Al Equiatomic Quaternary Heusler Alloys: XX'YZ equiatomic quaternary Heusler alloys (EQHA's) containing Cr, Al, and\nselect Group IVB elements ($\\textit{M}$ = Ti, Zr, Hf) and Group VB elements\n($\\textit{N}$ = V, Nb, Ta) were studied using state-of-the-art density\nfunctional theory to determine their effectiveness in spintronic applications.\nEach alloy is classified based on their spin-dependent electronic structure as\na half-metal, a spin gapless semiconductor, or a spin filter material. We\npredict several new fully-compensated ferrimagnetic spin filter materials with\nsmall electronic gaps and large exchange splitting allowing for robust spin\npolarization with small resistance. CrVZrAl, CrVHfAl, CrTiNbAl, and CrTiTaAl\nare identified as particularly robust spin filter candidates with an exchange\nsplitting of $\\sim 0.20$ eV. In particular, CrTiNbAl and CrTiTaAl have\nexceptionally small band gaps of $\\sim 0.10$ eV. Moreover, in these compounds,\na spin asymmetric electronic band gap is maintained in 2 of 3 possible atomic\narrangements they can take, making the electronic properties less susceptible\nto random site disorder. In addition, hydrostatic stress is applied to a subset\nof the studied compounds in order to determine the stability and tunability of\nthe various electronic phases. Specifically, we find the CrAlV$\\textit{M}$\nsubfamily of compounds to be exceptionally sensitive to hydrostatic stress,\nyielding transitions between all spin-dependent electronic phases.",
        "positive": "Effective potentials for 6-coordinated Boron: structural geometry\n  approach: We have built a database of ab-initio total energies for elemental Boron in\nover 60 hypothetical crystal structures of varying coordination $Z$, such that\nevery atom is equivalent. Fitting to each subset with a particular $Z$, we\nextract a classical effective potential, written as a sum over coordination\nshells and dominated by three-atom (bond angle dependent) terms. In the case\nZ=6 (lowest in energy and most relevant), the classical potential has a typical\nerror of 0.1 eV/atom, and favours the ``inverted-umbrells'' environment seen in\nreal Boron."
    },
    {
        "anchor": "Dominant Kinetic Pathways of Graphene Growth in Chemical Vapor\n  Deposition: The Role of Hydrogen: The most popular way to produce graphene nowadays is chemical vapor\ndeposition, where, surprisingly, H$_2$ gas is routinely supplied even though it\nis a byproduct itself. In this study, by identifying dominant growing pathways\nvia multiscale simulations, we unambiguously reveal the central role hydrogen\nplayed in graphene growth. Hydrogen can saturate the edges of a growing\ngraphene island to some extent, depending on the H$_2$ pressure. Although\ngraphene etching by hydrogen has been observed in experiment, hydrogen\nsaturation actually stabilizes graphene edges by reducing the detachment rates\nof carbon-contained species. Such a new picture well explains some puzzling\nexperimental observations and is also instrumental in growth protocol\noptimization for two-dimensional atomic crystal van der Waals epitaxy.",
        "positive": "Interfacial spin-orbit torque without bulk spin-orbit coupling: An electric current in the presence of spin-orbit coupling can generate a\nspin accumulation that exerts torques on a nearby magnetization. We demonstrate\nthat, even in the absence of materials with strong bulk spin-orbit coupling, a\ntorque can arise solely due to interfacial spin-orbit coupling, namely\nRashba-Eldestein effects at metal/insulator interfaces. In magnetically soft\nNiFe sandwiched between a weak spin-orbit metal (Ti) and insulator\n(Al$_2$O$_3$), this torque appears as an effective field, which is\nsignificantly larger than the Oersted field and sensitive to insertion of an\nadditional layer between NiFe and Al$_2$O$_3$. Our findings point to new routes\nfor tuning spin-orbit torques by engineering interfacial electric dipoles."
    },
    {
        "anchor": "Evidence of phase stability, topological phonon and temperature-induced\n  topological phase transition in rocksalt SnS and SnSe: Both SnS and SnSe have been experimentally and theoretically confirmed as\ntopological crystalline insulators in native rocksalt structure. Here, phononic\nstructure, thermodynamical properties and temperature dependent electron-phonon\ninteraction (EPI) have investigated for both the materials in rocksalt phase.\nPreviously performed theoretical studies have predicted the phase instability\nof SnS in this crystal structure at ambient condition. But, after a detailed\nstudy performing on the phonon calculation of SnS, we have predicted the phase\nstability of SnS with considering the Sn 4$p$ orbitals as valence states in\n$ab-initio$ calculation. The importance of long range Coulomb forces along with\nthe themodynamical properties are also described in detailed for both\nmaterials. The preliminary evidence of topological phonon is found along X-W\ndirection, where the linear band touching is observed as compared to type II\nWeyl phononic material ZnSe. The topological phase transition is seen for these\nmaterials due to EPI, where non-linear temperature dependent bandgap is\nestimated. The predicted value of transition temperature for SnS (SnSe) is\nfound to be $\\sim$700 K, where after this temperature the non-trivial to\ntrivial topological phase is seen. The strength of EPI shows more stronger\nimpact on the electronic structure of SnS than SnSe material. The reason of\nnon-linear behaviour of bandgap with rise in temperature is discussed with the\nhelp of temperature dependent linewidths and lineshifts of conduction band and\nvalence band due to EPI. The present study reveals the phase stability of SnS\nalong with the comparative study of thermal effect on EPI of SnS and SnSe.\nFurther, the possibility of temperature induced topological phase transition\nprovides one of important behaviour to apply these two materials for device\nmaking application.",
        "positive": "Computational 2D Materials Database: Electronic Structure of\n  Transition-Metal Dichalcogenides and Oxides: We present a comprehensive first-principles study of the electronic structure\nof 51 semiconducting monolayer transition metal dichalcogenides and -oxides in\nthe 2H and 1T hexagonal phases. The quasiparticle (QP) band structures with\nspin-orbit coupling are calculated in the $G_0W_0$ approximation and comparison\nis made with different density functional theory (DFT) descriptions. Pitfalls\nrelated to the convergence of $GW$ calculations for 2D materials are discussed\ntogether with possible solutions. The monolayer band edge positions relative to\nvacuum are used to estimate the band alignment at various heterostructure\ninterfaces. The sensitivity of the band structures to the in-plane lattice\nconstant is analysed and rationalized in terms of the electronic structure.\nFinally, the $q$-dependent dielectric functions and effective electron/hole\nmasses are obtained from the QP band structure and used as input to a 2D\nhydrogenic model to estimate exciton binding energies. Throughout the paper we\nfocus on trends and correlations in the electronic structure rather than\ndetailed analysis of specific materials. All the computed data is available in\nan open database."
    },
    {
        "anchor": "First principles study of bandgap tuning in GePbSe: Narrow bandgap and its tuning are important aspects of materials for their\ntechnological applications. In this context group IV VI semiconductors are one\nof the interesting candidates. In this paper, we explore the possibility of\nbandgap tuning in one of the family member of this family GeSe by using\nisoelectronic Pb doping. Our study is first principles based electronic\nstructure calculations of GePbSe. This study reveals that the Ge-p and Se-p\nstates are strongly hybridized in GeSe and shows a gap in the DOS at Ef in\nGeSe. This gap reduces systematically with simultaneous enhancement of the\nstates in the near Ef region as a function of Pb doping. This leads tuning of\nthe indirect bandgap in GeSe via Pb doping. The results of the indirect bandgap\ndecrement are consistent with the experimental findings. We propose a mechanism\nwhere the electrostatic effect of dopant Pb cation could be responsible for\nthese changes in the electronic structure of GeSe.",
        "positive": "Low-temperature photoluminescence of oxide-covered single-layer MoS2: We present a photoluminescence study of single-layer MoS2 flakes on SiO2\nsurfaces. We demonstrate that the luminescence peak position of flakes prepared\nfrom natural MoS2, which varies by up to 25 meV between individual as-prepared\nflakes, can be homogenized by annealing in vacuum, which removes adsorbates\nfrom the surface. We use HfO2 and Al2O3 layers prepared by atomic layer\ndeposition to cover some of our flakes. We clearly observe a suppression of the\nlow-energy luminescence peak observed for as-prepared flakes at low\ntemperatures, indicating that this peak originates from excitons bound to\nsurface adsorbates. We also observe different temperature-induced shifts of the\nluminescence peaks for the oxide-covered flakes. This effect stems from the\ndifferent thermal expansion coefficients of the oxide layers and the MoS2\nflakes. It indicates that the single-layer MoS2 flakes strongly adhere to the\noxide layers and are therefore strained."
    },
    {
        "anchor": "Light-Induced Transitions of Polar State and Domain Morphology of\n  Photo-Ferroelectric Nanoparticles: Using the Landau-Ginzburg-Devonshire approach, we study light-induced phase\ntransitions, evolution of polar state and domain morphology in\nphoto-ferroelectric nanoparticles (NPs). Light exposure increases the free\ncarrier density near the NP surface and may in turn induce phase transitions\nfrom the nonpolar paraelectric to the polar ferroelectric phase. Using the\nuniaxial photo-ferroelectric Sn2P2S6 as an example, we show that visible light\nexposure induces the appearance and vanishing of striped, labyrinthine or\ncurled domains and changes in the polarization switching hysteresis loop shape\nfrom paraelectric curves to double, pinched and single loops, as well as the\nshifting in the position of the tricritical point. Furthermore, we demonstrate\nthat an ensemble of non-interacting photo-ferroelectric NPs may exhibit\nsuperparaelectric-like features at the tricritical point, such as strongly\nfrequency-dependent giant piezoelectric and dielectric responses, which can\npotentially be exploited for piezoelectric applications.",
        "positive": "Infrared Single-Photon Detector based on Silicon Two-Photon Absorption: We propose a scheme for infrared single-photon detection based on two-photon\nabsorption at room-temperature in Si avalanche photodiodes, where the detected\nphoton's energy is lower than the bandgap and the energy difference is\ncomplemented by a pump field. A quantum non-perturbative model is developed for\nnon-degenerate two-photon absorption in direct and indirect semiconductors\nyielding proper non-divergent rates allowing device efficiency optimization.\nThe proposed monolithic detector is simple, miniature, integrable and does not\nrequire phase matching, while not compromising the performance and exhibiting\neven better efficiency than the competing up-conversion schemes (~1 order of\nmagnitude) for similar optical pump levels."
    },
    {
        "anchor": "Frictional drag between quantum wells mediated by fluctuating\n  electromagnetic field: We use the theory of the fluctuating electromagnetic field to calculate the\nfrictional drag between nearby two-and three dimensional electron systems. The\nfrictional drag results from coupling via a fluctuating electromagnetic field,\nand can be considered as the dissipative part of the van der Waals interaction.\nIn comparison with other similar calculations for semiconductor two-dimensional\nsystem we include retardation effects. We consider the dependence of the\nfrictional drag force on the temperature $T$, electron density and separation\n$d$. We find, that retardation effects become dominating factor for high\nelectron densities, corresponding thing metallic film, and suggest a new\nexperiment to test the theory. The relation between friction and heat transfer\nis also briefly commented on.",
        "positive": "(CuCl)LaTa2O7 and quantum phase transition in the (CuX)LaM2O7 family (X\n  = Cl, Br; M = Nb, Ta): We apply neutron diffraction, high-resolution synchrotron x-ray diffraction,\nmagnetization measurements, electronic structure calculations, and quantum\nMonte-Carlo simulations to unravel the structure and magnetism of\n(CuCl)LaTa2O7. Despite the pseudo-tetragonal crystallographic unit cell, this\ncompound features an orthorhombic superstructure, similar to the Nb-containing\n(CuX)LaNb2O7 with X = Cl and Br. The spin lattice entails dimers formed by the\nantiferromagnetic fourth-neighbor coupling J4, as well as a large number of\nnonequivalent interdimer couplings quantified by an effective exchange\nparameter Jeff. In (CuCl)LaTa2O7, the interdimer couplings are sufficiently\nstrong to induce the long-range magnetic order with the Neel temperature TN~7 K\nand the ordered magnetic moment of 0.53 mu_B, as measured with neutron\ndiffraction. This magnetic behavior can be accounted for by Jeff/J4~1.6 and\nJ4~16 K. We further propose a general magnetic phase diagram for the\n(CuCl)LaNb2O7-type compounds, and explain the transition from the gapped\nspin-singlet (dimer) ground state in (CuCl)LaNb2O7 to the long-range\nantiferromagnetic order in (CuCl)LaTa2O7 and (CuBr)LaNb2O7 by an increase in\nthe magnitude of the interdimer couplings Jeff/J_4, with the (CuCl)LaM2O7 (M =\nNb, Ta) compounds lying on different sides of the quantum critical point that\nseparates the singlet and long-range-ordered magnetic ground states."
    },
    {
        "anchor": "Direct observation of charge separation in an organic light harvesting\n  system by femtosecond time-resolved XPS: The ultrafast dynamics of photon-to-charge conversion in an organic light\nharvesting system is studied by femtosecond time-resolved X-ray photoemission\nspectroscopy (TR-XPS) at the free-electron laser FLASH. This novel experimental\ntechnique provides site-specific information about charge separation and\nenables the monitoring of free charge carrier generation dynamics on their\nnatural timescale, here applied to the model donor-acceptor system\nCuPc:C$_{60}$. A previously unobserved channel for exciton dissociation into\nmobile charge carriers is identified, providing the first direct, real-time\ncharacterization of the timescale and efficiency of charge generation from\nlow-energy charge-transfer states in an organic heterojunction. The findings\ngive strong support to the emerging realization that charge separation even\nfrom energetically disfavored excitonic states is contributing significantly,\nindicating new options for light harvesting in organic heterojunctions.",
        "positive": "Developments and applications of the OPTIMADE API for materials\n  discovery, design, and data exchange: The Open Databases Integration for Materials Design (OPTIMADE) application\nprogramming interface (API) empowers users with holistic access to a growing\nfederation of databases, enhancing the accessibility and discoverability of\nmaterials and chemical data. Since the first release of the OPTIMADE\nspecification (v1.0), the API has undergone significant development, leading to\nthe upcoming v1.2 release, and has underpinned multiple scientific studies. In\nthis work, we highlight the latest features of the API format, accompanying\nsoftware tools, and provide an update on the implementation of OPTIMADE in\ncontributing materials databases. We end by providing several use cases that\ndemonstrate the utility of the OPTIMADE API in materials research that continue\nto drive its ongoing development."
    },
    {
        "anchor": "Power dissipation and electrical breakdown in black phosphorus: We report operating temperatures and heating coefficients measured in a\nmulti-layer black phosphorus device as a function of injected electrical power.\nBy combining micro-Raman spectroscopy and electrical transport measurements, we\nhave observed a linear temperature increase up to 600K at a power dissipation\nrate of 0.896K\\mu m^3/mW. By further increasing the bias voltage, we determined\nthe threshold power and temperature for electrical breakdown and analyzed the\nfracture in the black phosphorus layer that caused the device failure by means\nof scanning electron microscopy and atomic force microscopy. The results will\nbenefit the research and development of electronics and optoelectronics based\non novel two-dimensional materials.",
        "positive": "Covalent Organic Functionalization of Graphene Nanosheets and Reduced\n  Graphene Oxide via 1,3-Dipolar Cycloaddition of Azomethine Ylide: Organic functionalization of graphene is successfully performed via\n1,3-dipolar cycloaddition of azomethine ylide in the liquid phase. The\ncomparison between 1-methyl-2-pyrrolidinone and N,N-dimethylformamide as\ndispersant solvents, and between sonication and homogenization as dispersion\ntechniques, proves N,N-dimethylformamide and homogenization as the most\neffective choice. The functionalization of graphene nanosheets and reduced\ngraphene oxide is confirmed using different techniques. Among them,\nenergy-dispersive X-ray spectroscopy allows to map the pyrrolidine ring of the\nazomethine ylide on the surface of functionalized graphene, while micro-Raman\nspectroscopy detects new features arising from the functionalization, which are\ndescribed in agreement with the power spectrum obtained from ab initio\nmolecular dynamics simulation. Moreover, X-ray photoemission spectroscopy of\nfunctionalized graphene allows the quantitative elemental analysis and the\nestimation of the surface coverage, showing a higher degree of\nfunctionalization for reduced graphene oxide. This more reactive behavior\noriginates from the localization of partial charges on its surface due to the\npresence of oxygen defects, as shown by the simulation of the electrostatic\nfeatures. Functionalization of graphene using 1,3-dipolar cycloaddition is\nshown to be a significant step towards the controlled synthesis of\ngraphene-based complex structures and devices at the nanoscale."
    },
    {
        "anchor": "Tailoring tunnel magnetoresistance by ultrathin Cr and Co interlayers: A\n  first-principles investigation of Fe/MgO/Fe junctions: We report on systematic ab-initio investigations of Co and Cr interlayers\nembedded in Fe(001)/MgO/Fe(001) magnetic tunnel junctions, focusing on the\nchanges of the electronic structure and the transport properties with\ninterlayer thickness. The results of spin-dependent ballistic transport\ncalculations reveal options to specifically manipulate the tunnel\nmagnetoresistance ratio. The resistance area products and the tunnel\nmagnetoresistance ratios show a monotonous trend with distinct oscillations as\na function of the Cr thickness. These modulations are directly addressed and\ninterpreted by means of magnetic structures in the Cr films and by complex band\nstructure effects. The characteristics for embedded Co interlayers are\nconsiderably influenced by interface resonances which are analyzed by the local\nelectronic structure.",
        "positive": "Novel two-dimensional photocatalyst SnN3 for overall water splitting\n  with enhanced visible-light absorption: We propose a novel excellent two-dimensional photocatalyst SnN3 monolayer\nusing first-principles calculations. The stability of SnN3 monolayer have been\nexamined via formation energy, phonon spectrum and ab initio molecular dynamics\ncalculations. Large optical absorption capacity plays significant role in the\nenhancement of photocatalytic splitting of water. The SnN3 monolayer have\nultra-high optical absorption capacity in visible region, which is as three and\nfour times as that of SnP3 and MoS2 monolayer, respectively. Available\npotential and appropriate band positions indicating the ability of overall\nwater splitting even in a wide strain range. Electronic properties of SnN3\nmonolayer can also be engineered effectively via the external strain, such as\nthe conversion from in-direct band gap to direct band gap. The applied electric\nfield splits the energy levels due to Stark effect, resulting in states\naccumulation and smaller gap width"
    },
    {
        "anchor": "Quantifying the search for solid Li-ion electrolyte materials by anion:\n  a data-driven perspective: We compile data and machine learned models of solid Li-ion electrolyte\nperformance to assess the state of materials discovery efforts and build new\ninsights for future efforts. Candidate electrolyte materials must satisfy\nseveral requirements, chief among them fast ionic conductivity and robust\nelectrochemical stability. Considering these two requirements, we find new\nevidence to suggest that optimization of the sulfides for fast ionic\nconductivity and wide electrochemical stability may be more likely than\noptimization of the oxides, and that the oft-overlooked chlorides and bromides\nmay be particularly promising families for Li-ion electrolytes. We also find\nthat the nitrides and phosphides appear to be the most promising material\nfamilies for electrolytes stable against Li-metal anodes. Furthermore, the\nspread of the existing data in performance space suggests that fast conducting\nmaterials that are stable against both Li metal and a >4V cathode are\nexceedingly rare, and that a multiple-electrolyte architecture is a more likely\npath to successfully realizing a solid-state Li metal battery by approximately\nan order of magnitude or more. Our model is validated by its reproduction of\nwell-known trends that have emerged from the limited existing data in recent\nyears, namely that the electronegativity of the lattice anion correlates with\nionic conductivity and electrochemical stability. In this work, we leverage the\nexisting data to make solid electrolyte performance trends quantitative for the\nfirst time, building a roadmap to complement material discovery efforts around\ndesired material performance.",
        "positive": "Giant magnetoimpedance in composite wires with insulator layer between\n  non-magnetic core and soft magnetic shell: A method for calculation of the magnetoimpedance in composite wires having an\ninsulator layer between non-magnetic core and soft magnetic shell is described.\nIt is assumed that the magnetic shell has a helical anisotropy and the driving\ncurrent flows through the core only. The distribution of eddy currents and\nexpressions for the impedance are found by means of a solution of Maxwell\nequations taking into account the magnetization dynamics within the shell\ngoverned by the Landau-Lifshitz equation. The effect of the insulator layer on\nthe magnetoimpedance is analyzed."
    },
    {
        "anchor": "Observation of surface superstructure induced by systematic vacancies in\n  the topological Dirac semimetal Cd$_{3}$As$_{2}$: The Dirac semimetal phase found in Cd$_{3}$As$_{2}$ is protected by a $C_{4}$\nrotational symmetry derived from a corkscrew arrangement of systematic Cd\nvacancies in its complicated crystal structure. It is therefore surprising that\nno microscopic observation, direct or indirect, of these systematic vacancies\nhas so far been described. To this end, we revisit the cleaved (112) surface of\nCd$_{3}$As$_{2}$ using a combined approach of scanning tunneling microscopy and\n\\textit{ab initio} calculations. We determine the exact position of the (112)\nplane at which Cd$_{3}$As$_{2}$ naturally cleaves, and describe in detail a\nstructural periodicity found at the reconstructed surface, consistent with that\nexpected to arise from the systematic Cd vacancies. This reconciles the current\nstate of microscopic surface observations with those of crystallographic and\ntheoretical models, and demonstrates that this vacancy superstructure, central\nto the preservation of the Dirac semimetal phase, survives the cleavage process\nand retains order at the surface.",
        "positive": "Alloy surface segregation in reactive environments: A first-principles\n  atomistic thermodynamics study of Ag3Pd(111) in oxygen atmospheres: We present a first-principles atomistic thermodynamics framework to describe\nthe structure, composition and segregation profile of an alloy surface in\ncontact with a (reactive) environment. The method is illustrated with the\napplication to a Ag3Pd(111) surface in an oxygen atmosphere, and we analyze\ntrends in segregation, adsorption and surface free energies. We observe a wide\nrange of oxygen adsorption energies on the various alloy surface\nconfigurations, including binding that is stronger than on a Pd(111) surface\nand weaker than that on a Ag(111) surface. This and the consideration of even\nsmall amounts of non-stoichiometries in the ordered bulk alloy are found to be\ncrucial to accurately model the Pd surface segregation occurring in\nincreasingly O-rich gas phases."
    },
    {
        "anchor": "Prediction of electrically-induced magnetic reconstruction at the\n  manganite/ferroelectric interface: The control of magnetization via the application of an electric field, known\nas magnetoelectric coupling, is among the most fascinating and active research\nareas today. In addition to fundamental scientific interest, magnetoelectric\neffects may lead to new device concepts for data storage and processing. There\nare several known mechanisms for magnetoelectric coupling that include\nintrinsic effects in single-phase materials, strain induced coupling in\ntwo-phase composites, and electronically-driven effects at interfaces. Here we\nexplore a different type of magnetoelectric effect at a\nferromagnetic-ferroelectric interface: magnetic reconstruction induced by\nswitching of electric polarization. We demonstrate this effect using\nfirst-principles calculations of a La1-xAxMnO3/BaTiO3 (001) interface, where A\nis a divalent cation. By choosing the doping level x to be near a transition\nbetween magnetic phases we show that the reversal of the ferroelectric\npolarization of BaTiO3 leads to a change in the magnetic order at the interface\nfrom ferromagnetic to antiferromagnetic. This predicted electrically-induced\nmagnetic reconstruction at the interface represents a substantial interfacial\nmagnetoelectric effect.",
        "positive": "Inducing superconductivity in Weyl semi-metal microstructures by\n  selective ion sputtering: By introducing a superconducting gap in Weyl- or Dirac semi-metals, the\nsuperconducting state inherits the non-trivial topology of their electronic\nstructure. As a result, Weyl superconductors are expected to host exotic\nphenomena such as non-zero-momentum pairing due to their chiral node structure,\nor zero- energy Majorana modes at the surface. These are of fundamental\ninterest to improve our understanding of correlated topological systems, and\nmoreover practical applications in phase coherent devices and quantum\napplications have been proposed. Proximity-induced superconductivity promises\nto allow such experiments on non-superconducting Weyl semi-metals. Here we show\na new route to reliably fabricating superconducting microstructures from the\nnon-superconducting Weyl semi-metal NbAs under ion irradiation. The significant\ndifference in the surface binding energy of Nb and As leads to a natural\nenrichment of Nb at the surface during ion milling, forming a superconducting\nsurface layer (Tc~3.5K). Being formed from the target crystal itself, the ideal\ncontact between the superconductor and the bulk may enable an effective gapping\nof the Weyl nodes in the bulk due to the proximity effect. Simple ion\nirradiation may thus serve as a powerful tool to fabricating topological\nquantum devices from mono-arsenides, even on an industrial scale."
    },
    {
        "anchor": "Hydrothermal Synthesis of Carbon Nanospheres: The experiment was conducted to synthesize carbon nanospheres of different\nsizes by controlling the temperature in polycondensation reaction of glucose\nunder hydrothermal process. The surface morphology, structural, optical, and\nthermal properties of as synthesized particles were characterized using TEM,\nSEM, XRD, Raman spectroscopy, TGA, and DSC. The particles morphology and\ndispersity were modified and reduced their size after calcination at $500^{o}\nC$ in comparison to those without calcinated. Thermal study also indicates\nparticles change their phase from amorphous to crystalline and achieve thermal\nstability after $520^{o}C$, which can also be verified by presence of D-band\nand G-band in Raman spectrum. Overall results indicate that the carbon\nnanospheres are hard solids and highly dispersed with size ranges from 50 nm to\n300 nm.",
        "positive": "Laser Stimulated Grain Growth in 304 Stainless Steel Anodes for Reduced\n  Hydrogen Outgassing: Metal anodes in high power source (HPS) devices erode during operation due to\nhydrogen outgassing and plasma formation, both of which are thermally driven\nphenomena generated by the electron beam impacting the anode s surface. This\nlimits the lowest achievable pressure in an HPS device, which reduces its\nefficiency. Laser surface melting the 304 stainless steel anodes by a\ncontinuous wave fiber laser showed a reduction in hydrogen outgassing by a\nfactor of ~4 under 50 keV electron bombardment, compared to that from untreated\nstainless steel. This is attributed to an increase in the grain size (from 40 -\n3516 micrometer2), which effectively reduces the number of characterized grain\nboundaries that serve as hydrogen trapping sites, making such laser treated\nmetals excellent candidates for use in vacuum electronics."
    },
    {
        "anchor": "Molecular Dynamics Studies of Dislocations in CdTe Crystals from a New\n  Bond Order Potential: Cd1-xZnxTe (CZT) crystals are the leading semiconductors for radiation\ndetection, but their application is limited by the high cost of detector-grade\nmaterials. High crystal costs primarily result from property non-uniformity\nthat causes low manufacturing yield. While tremendous efforts have been made in\nthe past to reduce Te inclusions / precipitates in CZT, this has not resulted\nin an anticipated improvement in material property uniformity. Moreover, it is\nrecognized that in addition to Te particles, dislocation cells can also cause\nelectric field perturbation and the associated property non-uniformity. Further\nimprovement of the material, therefore, requires that dislocations in CZT\ncrystals be understood and controlled. Here we use a recently developed CZT\nbond order potential to perform representative molecular dynamics simulations\nto study configurations, energies, and mobilities of 29 different types of\npossible dislocations in CdTe (i.e., x = 1) crystals. An efficient method to\nderive activation free energies and activation volumes of thermally activated\ndislocation motion will be explored. Our focus gives insight into understanding\nimportant dislocations in the material, and gives guidance toward experimental\nefforts for improving dislocation network structures in CZT crystals.",
        "positive": "Electromagnetic Wave Propagation in Media with Indefinite Permittivity\n  and Permeability Tensors: We study the behavior of wave propagation in materials for which not all of\nthe principle elements of the permeability and permittivity tensors have the\nsame sign. We find that a wide variety of effects can be realized in such\nmedia, including negative refraction, near-field focusing and high impedance\nsurface reflection. In particular a bi-layer of these materials can transfer a\nfield distribution from one side to the other, including near-fields, without\nrequiring internal exponentially growing waves."
    },
    {
        "anchor": "Long Term Friction: from Stick-Slip to Stable Sliding: We have devised an original laboratory experiment where we investigate the\nfrictional behaviour of a single crystal salt slider over a large number of\ndeformation cycles. Because of its physical properties, salt, a surrogate for\nnatural faults, allows for friction and plastic deformation and pressure\nsolution creep to be efficient on the same timescale. During the same\nexperiment, we observe a continuous change of the frictional behaviour of the\nslider under constant conditions of stiffness, temperature and loading\nvelocity. The stick-slip regime is progressively vanishing, eventually reaching\nthe stable sliding regime. Concomitantly, the contact interface, observed under\nthe microscope, develops a striated morphology with contact asperities increase\nin length and width, arguing for an increase in the critical slip distance dc.\nComplementary experiments including velocity jumps show that the frictional\nparameters of the rate and state friction law, a and b, progressively vanish\nwith the cumulative slip. In our experimental conditions, the ultimate stage of\nfriction is therefore rate and state independent.",
        "positive": "Room-temperature surface multiferroicity in Y$_2$NiMnO$_6$ nanorods: We report observation of surface-defect-induced room temperature\nmultiferroicity - surface ferromagnetism ($M_S$ at 50 kOe $\\sim$0.005 emu/g),\nferroelectricity ($P_R$ $\\sim$2 nC/cm$^2$), and significantly large\nmagnetoelectric coupling (decrease in $P_R$ by $\\sim$80\\% under $\\sim$15 kOe\nfield) - in nanorods (diameter $\\sim$100 nm) of double perovskite\nY$_2$NiMnO$_6$ compound. In bulk form, this system exhibits multiferroicity\nonly below its magnetic transition temperature $T_N$ $\\approx$ 70 K. On the\nother hand, the oxygen vacancies, formed at the surface region (thickness\n$\\sim$10 nm) of the nanorods, yield long-range magnetic order as well as\nferroelectricity via Dzyloshinskii-Moriya exchange coupling interactions with\nstrong Rashba spin-orbit coupling. Sharp drop in $P_R$ under magnetic field\nindicates strong cross-coupling between magnetism and ferroelectricity as well.\nObservation of room temperature magnetoelectric coupling in nanoscale for a\ncompound which, in bulk form, exhibits multiferroicity only below 70 K\nunderscores an alternative pathway for inducing magnetoelectric multiferroicity\nvia surface defects and, thus, in line with magnetoelectric property observed,\nfor example, in domain walls or boundaries or interfaces of heteroepitaxially\ngrown thin films which do not exhibit such features in their bulk."
    },
    {
        "anchor": "Two-Dimensional Bipolar Magnetic Semiconductor with High Curie\n  Temperature and Electrically Controllable Spin Polarization Realized in\n  Exfoliated Cr(pyrazine)$_2$ Monolayer: Exploring two-dimensional (2D) magnetic semiconductors with room temperature\nmagnetic ordering and electrically controllable spin polarization is a highly\ndesirable but challenging task for nanospintronics. Here, through first\nprinciples calculations, we propose to realize such a material by exfoliating\nthe recently synthesized organometallic layered crystal\nLi$_{0.7}$[Cr(pyz)$_2$]Cl$_{0.7}$0.25$\\cdot$(THF) (pyz = pyrazine, THF =\ntetrahydrofuran) [Science 370, 587 (2020)]. The feasibility of exfoliation is\nconfirmed by the rather low exfoliation energy of 0.27 J/m$^2$, even smaller\nthan that of graphite. In exfoliated Cr(pyz)$_2$ monolayer, each pyrazine ring\ngrabs one electron from the Cr atom to become a radical anion, then a strong\n$d$-$p$ direct exchange magnetic interaction emerges between Cr cations and\npyrazine radicals, resulting in room temperature ferrimagnetism with a Curie\ntemperature of 342 K. Moreover, Cr(pyz)$_2$ monolayer is revealed to be an\nintrinsic bipolar magnetic semiconductor where electrical doping can induce\nhalf-metallic conduction with controllable spin-polarization direction.",
        "positive": "Heat conduction of single-walled carbon nanotube isotope-superlattice\n  structures: A molecular dynamics study: Heat conduction of single-walled carbon nanotubes (SWNTs)\nisotope-superlattice is investigated by means of classical molecular dynamics\nsimulations. Superlattice structures were formed by alternately connecting\nSWNTs with different masses. On varying the superlattice period, the critical\nvalue with minimum effective thermal conductivity was identified, where\ndominant physics switches from zone-folding effect to thermal boundary\nresistance of lattice interface. The crossover mechanism is explained with the\nenergy density spectra where zone-folding effects can be clearly observed. The\nresults suggest that the critical superlattice period thickness depends on the\nmean free path distribution of diffusive-ballistic phonons. The reduction of\nthe thermal conductivity with superlattice structures beats that of the\none-dimensional alloy structure, though the minimum thermal conductivity is\nstill slightly higher than the value obtained by two-dimensional random mixing\nof isotopes."
    },
    {
        "anchor": "Highly linear polarized emission at telecom bands in InAs/InP quantum\n  dot-nanowires by geometry tailoring: Nanowire (NW)-based opto-electronic devices require certain engineering in\nthe NW geometry to realize polarized-dependent light sources and\nphotodetectors. We present a growth procedure to produce InAs/InP quantum\ndot-nanowires (QD-NWs) with an elongated top-view cross-section relying on the\nvapor-liquid-solid method using molecular beam epitaxy. By interrupting the\nrotation of the sample during the radial growth sequence of the InP shell,\nhexagonal asymmetric (HA) NWs with long/short cross-section axes were obtained\ninstead of the usual symmetrical shape. Polarization-resolved photoluminescence\nmeasurements have revealed a significant influence of the asymmetric shaped NWs\non the InAs QD emission polarization with the photons being mainly polarized\nparallel to the NW long cross-section axis. A degree of linear polarization\n(DLP) up to 91% is obtained, being at the state of the art for the reported DLP\nvalues from QD-NWs. More importantly, the growth protocol herein is fully\ncompatible with the current applications of HA NWs covering a wide range of\ndevices such as polarized light emitting diodes and photodetectors.",
        "positive": "Ab Initio Calculations of XUV Ground and Excited States for First-Row\n  Transition Metal Oxides: Transient X-ray spectroscopies have become ubiquitous in studying\nphotoexcited dynamics in solar energy materials due to their sensitivity to\ncarrier occupations and local chemical or structural dynamics. The\ninterpretation of solid-state photoexcited dynamics, however, is complicated by\nthe core-hole perturbation and the resulting many-body dynamics. Here, an ab\ninitio, Bethe-Salpeter equation (BSE) approach is developed that can\nincorporate photoexcited state effects for solid-state materials. The extreme\nultraviolet (XUV) absorption spectra for the ground, photoexcited, and\nthermally expanded states of first row transition metal oxides - $TiO_2,\n\\alpha-Cr_2O_3, \\beta-MnO_2, \\alpha-Fe_2O_3, Co_3O_4, NiO, CuO, and ZnO$ - are\ncalculated to demonstrate the accuracy of this approach. The theory is used to\ndecompose the core-valence excitons into the separate components of the X-ray\ntransition Hamiltonian for each of the transition metal oxides investigated.\nThe decomposition provides a physical intuition about the origins of XUV\nspectral features as well as how the spectra will change following\nphotoexcitation. The method is easily generalized to other K, L, M, and N edges\nto provide a general approach for analyzing transient X-ray absorption or\nreflection data."
    },
    {
        "anchor": "Direct observation of Space Charge Dynamics by picosecond Low Energy\n  Electron Scattering: The electric field governing the dynamics of space charge produced by high\nintensity femtosecond laser pulses focused on a copper surface is investigated\nby time-resolved low-energy-electron-scattering. The pump-probe experiment has\na measured temporal resolution of better than 35 ps at 55 eV probe electron\nenergy. The probe electron acceleration due to space charge is reproduced\nwithin a 3-dimensional non-relativistic model, which determines an effective\nnumber of electrons in the space charge electron cloud and its initial\ndiameter. Comparison of the simulations with the experiments indicates a\nCoulomb explosion, which is consistent with transients in the order of 1 ns,\nthe terminal kinetic energy of the cloud and the thermoemission currents\npredicted by the Richardson-Dushman formula.",
        "positive": "The role of random electric fields in relaxors: PbZr_{1-x}Ti_xO_3 (PZT) and Pb(Mg_{1/3}Nb_{2/3})_{1-x}Ti_xO_3 (PMN-$x$PT) are\ncomplex lead-oxide perovskites that display exceptional piezoelectric\nproperties for pseudorhombohedral compositions near a tetragonal phase\nboundary. In PZT these compositions are ferroelectrics, but in PMN-xPT they are\nrelaxors because the dielectric permittivity is frequency dependent and\nexhibits non-Arrhenius behavior. We show that the nanoscale structure unique to\nPMN-xPT and other lead-oxide perovskite relaxors is absent in PZT and\ncorrelates with a greater than 100% enhancement of the longitudinal\npiezoelectric coefficient in PMN-xPT relative to that in PZT. By comparing\ndielectric, structural, lattice dynamical, and piezoelectric measurements on\nPZT and PMN-xPT, two nearly identical compounds that represent weak and strong\nrandom electric field limits, we show that quenched (static) random fields\nestablish the relaxor phase and identify the order parameter."
    },
    {
        "anchor": "Sample-dependent Dirac point gap in MnBi$_2$Te$_4$ and its response to\n  the applied surface charge: a combined photoemission and ab initio study: Recently discovered intrinsic antiferromagnetic topological insulator\nMnBi$_2$Te$_4$ presents an exciting platform for realization of the quantum\nanomalous Hall effect and a number of related phenomena at elevated\ntemperatures. An important characteristic making this material attractive for\napplications is its predicted large magnetic gap at the Dirac point (DP).\nHowever, while the early experimental measurements reported on large DP gaps, a\nnumber of recent studies claimed to observe a gapless dispersion of the\nMnBi$_2$Te$_4$ Dirac cone. Here, using micro($\\mu$)-laser angle-resolved\nphotoemission spectroscopy, we study the electronic structure of 15 different\nMnBi$_2$Te$_4$ samples, grown by two different chemists groups. Based on the\ncareful energy distribution curves analysis, the DP gaps between 15 and 65 meV\nare observed, as measured below the N\\'eel temperature at about 10-16 K. At\nthat, roughly half of the studied samples show the DP gap of about 30 meV,\nwhile for a quarter of the samples the gaps are in the 50 to 60 meV range.\nSummarizing the results of both our and other groups, in the currently\navailable MnBi$_2$Te$_4$ samples the DP gap can acquire an arbitrary value\nbetween a few and several tens of meV. Further, based on the density functional\ntheory, we discuss a possible factor that might contribute to the reduction of\nthe DP gap size, which is the excess surface charge that can appear due to\nvarious defects in surface region. We demonstrate that the DP gap is influenced\nby the applied surface charge and even can be closed, which can be taken\nadvantage of to tune the MnBi$_2$Te$_4$ DP gap size.",
        "positive": "Ab-initio prediction of the electronic and optical excitations in\n  polythiophene: isolated chains versus bulk polymer: We calculate the electronic and optical excitations of polythiophene using\nthe GW approximation for the electronic self-energy, and include excitonic\neffects by solving the electron-hole Bethe-Salpeter equation. Two different\nsituations are studied: excitations on isolated chains and excitations on\nchains in crystalline polythiophene. The dielectric tensor for the crystalline\nsituation is obtained by modeling the polymer chains as polarizable line\nobjects, with a long-wavelength polarizability tensor obtained from the\nab-initio polarizability function of the isolated chain. With this model\ndielectric tensor we construct a screened interaction for the crystalline case,\nincluding both intra- and interchain screening. In the crystalline situation\nboth the quasi-particle band gap and the exciton binding energies are\ndrastically reduced in comparison with the isolated chain. However, the optical\ngap is hardly affected. We expect this result to be relevant for conjugated\npolymers in general."
    },
    {
        "anchor": "Propagation of Acoustical Wave in Finite Cylindrical Solid Bar\n  surrounded by Semi-Infinite Porous Media saturated with Fluid: We established the propagation equation of acoustical wave in media with the\nsolid/porous media cylindrical boundary and obtained the analytic solution. We\nsuggested the boundary condition on solid-porous media cylindrical boundary.\nBased on that, we introduced the dispersion equation, and constructed the\nalgorithm to perform numerical calculation and analysis of dispersion equation.",
        "positive": "Chemical potential shift and gap-state formation in SrTiO$_{3-\u03b4}$\n  revealed by photoemission spectroscopy: In this study, we report on investigations of the electronic structure of\nSrTiO$_3$ annealed at temperature ranging between 550 and 840$^\\circ$C in an\nultrahigh vacuum. Annealing induced oxygen vacancies (O$_{vac}$) impart\nconsiderable changes in the electronic structure of SrTiO$_3$. Using core-level\nphotoemission spectroscopy, we have studied the chemical potential shift\n($\\Delta\\mu$) as a function of annealing temperature. The result shows that the\nchemical potential monotonously increases with electron doping in\nSrTiO$_{3-\\delta}$. The monotonous increase of the chemical potential rules out\nthe existence of electronic phase separation in the sample. Using valence band\nphotoemission, we have demonstrated the formation of a low density of states at\nthe near Fermi level electronic spectrum of SrTiO$_{3-\\delta}$. The gap-states\nwere observed by spectral weight transfer over a large energy scale of the\nstoichiometric band gap of SrTiO$_3$ system leading finally to an insulator -\nmetal transition. We have interpreted our results from the point of structural\ndistortions induced by oxygen vacancies."
    },
    {
        "anchor": "Tensorial stress-plastic strain fields in $\u03b1$-$\u03c9$ Zr mixture,\n  transformation kinetics, and friction in diamond anvil cell: Various phenomena (phase transformations, chemical reactions, and friction)\nunder high pressures in diamond anvil cell are strongly affected by fields of\nall components of stress and plastic strain tensors. However, they could not be\nmeasured. Even measured pressure distribution contains significant error. Here,\nwe suggest coupled experimental-analytical-computational approaches utilizing\nsynchrotron X-ray diffraction, to solve an inverse problem and find all these\nfields and friction rules before, during, and after $\\alpha$-$\\omega$ phase\ntransformation in strongly plastically predeformed Zr. Due to advanced\ncharacterization, the minimum pressure for the strain-induced $\\alpha$-$\\omega$\nphase transformation is changed from 1.36 to 2.7 GPa. It is independent of the\ncompression-shear path. The theoretically predicted plastic strain-controlled\nkinetic equation is verified and quantified. Obtained results open\nopportunities for developing quantitative high-pressure/stress science,\nincluding mechanochemistry, material synthesis, and tribology.",
        "positive": "X-ray detected ferromagnetic resonance techniques for the study of\n  magnetization dynamics: Element-specific spectroscopies using synchrotron-radiation can provide\nunique insights into materials properties. The recently developed technique of\nX-ray detected ferromagnetic resonance (XFMR) allows studying the magnetization\ndynamics of magnetic spin structures. Magnetic sensitivity in XFMR is obtained\nfrom the X-ray magnetic circular dichroism (XMCD) effect, where the phase of\nthe magnetization precession of each magnetic layer with respect to the\nexciting radio frequency is obtained using stroboscopic probing of the spin\nprecession. Measurement of both amplitude and phase response in the magnetic\nlayers as a function of bias field can give a clear signature of spin-transfer\ntorque (STT) coupling between ferromagnetic layers due to spin pumping. Over\nthe last few years, there have been new developments utilizing X-ray scattering\ntechniques to reveal the precessional magnetization dynamics of ordered spin\nstructures in the GHz frequency range. The techniques of diffraction and\nreflectometry ferromagnetic resonance (DFMR and RFMR) provide novel ways for\nthe probing of the dynamics of chiral and multilayered magnetic materials,\nthereby opening up new pathways for the development of high-density and\nlow-energy consumption data processing solutions."
    },
    {
        "anchor": "Magnetic droplet nucleation with homochiral Neel domain wall: We investigate the effect of the Dzyaloshinskii Moriya interaction (DMI) on\nmagnetic domain nucleation in a ferromagnetic thin film with perpendicular\nmagnetic anisotropy. We propose an extended droplet model to determine the\nnucleation field as a function of the in-plane field. The model can explain the\nexperimentally observed nucleation in a CoNi microstrip with the interfacial\nDMI. The results are also reproduced by micromagnetic simulation based on the\nstring model. The electrical measurement method proposed in this study can be\nwidely used to quantitatively determine the DMI energy density.",
        "positive": "Evidence of spin-phonon coupling in CrSiTe$_3$: We present the Raman scattering results on layered 2D semiconducting\nferromagnetic compound CrSiTe$_3$. Four Raman active modes, predicted by\nsymmetry, have been observed and assigned. The experimental results are\nsupported by DFT calculations. The self-energies of the $A_g^3$ and the $E_g^3$\nsymmetry modes exhibit unconventional temperature evolution around 180 K. In\naddition, the doubly degenerate $E_g^3$ mode shows clear change of asymmetry in\nthe same temperature region. The observed behavior is consistent with the\npresence of the previously reported short-range magnetic order and the strong\nspin-phonon coupling."
    },
    {
        "anchor": "Self-consistent on-site and inter-site Hubbard parameters within DFT+U+V\n  for UO$_2$ using density-functional perturbation theory: To apply the Hubbard-corrected density-functional theory for predicting some\nknown materials' properties, the Hubbard parameters are usually so tuned that\nthe calculations give results in agreement with some experimental data and then\none uses the tuned model to predict unknown properties. However, in designing\nnew unknown novel materials there is no data to fit the parameters and\ntherefore self-consistent determination of these parameters is crucial. In this\nwork, using the new method formulated by others, which is based on\ndensity-functional perturbation theory, we have calculated self-consistently\nthe Hubbard parameters for UO$_2$ crystal within different popular\nexchange-correlation approximations. The calculated ground-state lattice\nconstants and electronic band-gaps are compared with experiment and shown that\nPBE-sol lead to results in best agreement with experiment.",
        "positive": "Friedel oscillations and helium bubble ordering in molybdenum: Helium ions implanted into metals can evolve into ordered bubbles isomorphic\nto the host lattice. Long-range elastic interaction is generally believed to\ndrive the formation of bubble superlattice, but little is known about the\nthermodynamics at the very initial stage. Our first-principles calculations\ndemonstrate that in molybdenum, Friedel oscillations induced by individual\nhelium generate both potential barriers and wells for helium clustering at\nshort He-He distances. Such repulsion and attraction at high concentration\nprovide a thermodynamic diving force to assist lining up randomly distributed\nHe atoms into ordered bubbles. Friedel oscillations might have general impact\non solute-solute interactions in alloys."
    },
    {
        "anchor": "Weakly Trapped, Charged, and Free Excitons in Single-Layer MoS2 in the\n  Presence of Defects, Strain, and Charged Impurities: Few- and single-layer MoS2 host substantial densities of defects. They are\nthought to influence the doping level, the crystal structure, and the binding\nof electron-hole pairs. We disentangle the concomitant spectroscopic expression\nof all three effects and identify to what extent they are intrinsic to the\nmaterial or extrinsic to it, i.e., related to its local environment. We do so\nby using different sources of MoS2 -- a natural one and one prepared at high\npressure and high temperature -- and different substrates bringing varying\namounts of charged impurities and by separating the contributions of internal\nstrain and doping in Raman spectra. Photoluminescence unveils various optically\nactive excitonic complexes. We discover a defect-bound state having a low\nbinding energy of 20 meV that does not appear sensitive to strain and doping,\nunlike charged excitons. Conversely, the defect does not significantly dope or\nstrain MoS2. Scanning tunneling microscopy and density functional theory\nsimulations point to substitutional atoms, presumably individual nitrogen atoms\nat the sulfur site. Our work shows the way to a systematic understanding of the\neffect of external and internal fields on the optical properties of\ntwo-dimensional materials.",
        "positive": "Anisotropic paramagnetism of monoclinic Nd2Ti2O7 single crystals: The anisotropic paramagnetism and specific heat in Nd2Ti2O7 single crystals\nare investigated. Angular dependence of the magnetization and Weiss\ntemperatures show the dominant role of the crystal field effect in the\nmagnetization. By incorporating the results from the diluted samples,\ncontributions to Weiss temperature from exchange interactions and crystal field\ninteractions are isolated. The exchange interactions are found to be\nferromagnetic, while the crystal field contributes a large negative part to the\nWeiss temperature, along all three crystallographic directions. The specific\nheat under magnetic field reveals a two-level Schottky ground state scheme, due\nto the Zeeman splitting of the ground state doublet, and the g-factors are thus\ndetermined. These observations provide solid foundations for further\ninvestigations of Nd2Ti2O7."
    },
    {
        "anchor": "Logarithmic behavior of degradation dynamics in metal--oxide\n  semiconductor devices: In this paper the authors describe a theoretical simple statistical modelling\nof relaxation process in metal-oxide semiconductor devices that governs its\ndegradation. Basically, starting from an initial state where a given number of\ntraps are occupied, the dynamics of the relaxation process is measured\ncalculating the density of occupied traps and its fluctuations (second moment)\nas function of time. Our theoretical results show a universal logarithmic law\nfor the density of occupied traps $\\bar{<n(t)>} \\sim \\phi (T,E_{F}) (A+B \\ln\nt)$, i.e., the degradation is logarithmic and its amplitude depends on the\ntemperature and Fermi Level of device. Our approach reduces the work to the\naverages determined by simple binomial sums that are corroborated by our Monte\nCarlo simulations and by experimental results from literature, which bear in\nmind enlightening elucidations about the physics of degradation of\nsemiconductor devices of our modern life.",
        "positive": "Bulk Assembly of Organic Metal Halide Nanoribbons: Organic metal halide hybrids with low-dimensional structures at the molecular\nlevel have received great attention recently for their exceptional structural\ntunability and unique photophysical properties. Here we report for the first\ntime the synthesis and characterization of a one-dimensional (1D) organic metal\nhalide hybrid material, which contains metal halide nanoribbons with a width of\nthree octahedral units. It is found that this material with a chemical formula\nC$_8$H$_{28}$N$_5$Pb$_3$Cl$_{11}$ shows a dual emission with a\nphotoluminescence quantum efficiency (PLQE) of around 25% under ultraviolet\n(UV) light irradiation. Photophysical studies and density functional theory\n(DFT) calculations suggest the coexisting of delocalized free excitons and\nlocalized self-trapped excitons in metal halide nanoribbons leading to the dual\nemission. This work shows once again the exceptional tunability of organic\nmetal halide hybrids that bridge between molecular systems with localized\nstates and crystalline ones with electronic bands."
    },
    {
        "anchor": "Bistability of the BiOi complex and its implications on evaluating the\n  acceptor removal: The dependencies of the B$_{i}$O$_{i}$ defect concentration on doping,\nirradiation fluence and particle type in p-type silicon diodes have been\ninvestigated. We evidenced that large data scattering occurs for fluences above\n$10^{12}$ 1 MeV neutrons/cm$^2$, becoming significant larger for higher\nfluences. We show that the B$_{i}$O$_{i}$ defect is metastable, with two\nconfigurations A and B, of which only A is detected by Deep Level Transient\nSpectroscopy and Thermally Stimulated Currents techniques. The defect's\nelectrical activity is influenced by the inherent variations in ambient and\nprocedural experimental conditions, resulting not only in a large scattering of\nthe results coming from the same type of measurement but making any correlation\nbetween different types of experiments difficult. It is evidenced that the\nvariations in [B$_{i}$O$_{i}^\\mathrm{A}$] are triggered by subjecting the\nsamples to an excess of carriers, by either heating or an inherent short\nexposure to ambient light when manipulating the samples prior to experiments.\nIt causes $\\approx$7h variations in both, the [B$_{i}$O$_{i}^\\mathrm{A}$] and\nin the effective space charge. The analyses of structural damage in a diode\nirradiated with 10$^{19}$ 1 MeV neutrons/cm$^2$ revealed that the Si structure\nremains crystalline and vacancies and interstitials organize in parallel tracks\nnormal to the Si-SiO$_{2}$ interface.",
        "positive": "Emergent impervious band crossing in the bulk in topological nodal line\n  semimetal ZrAs$_2$: Topological nodal line semimetals (TSMs) represent a unique class of\nmaterials with intriguing electronic structures and rich of symmetries, hosting\nelectronic states with non-trivial topological properties. Among these,\nZrAs$_2$ stands out, characterized by its nodal lines forming continuous loops\nin momentum space, governed by non-symmorphic symmetries. This study integrates\nangle-resolved photoemission spectroscopy (ARPES) with density functional\ntheory (DFT) calculations to explore the electronic states of ZrAs$_2$. In\nARPES scans, we observed a distinctive nodal loop structure observed at lower\nexcitation energies of 30 and 50 eV. Our results, supported by calculations\nbased on DFT, unveil symmetry-enforced Dirac-like band crossings anchored at\nspecific points in the Brillouin zone, with particular emphasis on the S point.\nSurface bands and bulk states near the crossing are elucidated through slab\ncalculations, corroborating experimental findings. DFT calculations also show\nthe existence of several spin-orbit coupling (SOC) resilient semi-Dirac\ncrossings pinned at Z point. This comprehensive investigation sheds light on\nthe intricate electronic behaviors of ZrAs$_2$ with the involved symmetries,\nimportant for fundamental understanding of topological nodal line semimetals."
    },
    {
        "anchor": "Band filling and cross quantum capacitance in ion gated semiconducting\n  transition metal dichalcogenide monolayers: Ionic liquid gated field-effect transistors (FETs) based on semiconducting\ntransition metal dichalcogenides (TMDs) are used to study a rich variety of\nextremely interesting physical phenomena, but important aspects of how charge\ncarriers are accumulated in these systems are not understood. We address these\nissues by means of a systematic experimental study of transport in monolayer\nMoSe$_2$ and WSe$_2$ as a function of magnetic field and gate voltage,\nexploring accumulated densities of carriers ranging from approximately\n10$^{14}$ cm$^{-2}$ holes in the valence band to 4x10$^{14}$ cm$^{-2}$\nelectrons in the conduction band. We identify the conditions when the chemical\npotential enters different valleys in the monolayer band structure (the K and Q\nvalley in the conduction band and the two spin-split K-valleys in the valence\nband) and find that an independent electron picture describes the occupation of\nstates well. Unexpectedly, however, the experiments show very large changes in\nthe device capacitance when multiple valleys are occupied that are not at all\ncompatible with the commonly expected quantum capacitance contribution of these\nsystems, $\\textit{C}$$_Q$=$\\textit{e}^2$/(d$\\mu$/d$\\textit{n}$). This\nunexpected behavior is attributed to the presence of a cross quantum\ncapacitance, which originates from screening of the electric field generated by\ncharges on one plate from charges sitting on the other plate. Our findings\ntherefore reveal an important contribution to the capacitance of physical\nsystems that had been virtually entirely neglected until now. (short abstract\ndue to size limitations - full abstract in the manuscript)",
        "positive": "Vacancy Effects on Electric and Thermoelectric Properties of Zigzag\n  Silicene Nanoribbons: We study the crystal reconstruction in the presence of monovacancies (MVs),\ndivacancies (DVs) and linear vacancies (LVs) in a zigzag silicene nanoribbon\n(ZSiNR) with transversal symmetry. Their influence on the electric and\nthermoelectric properties is assessed by the density functional theory combined\nwith the nonequilibrium Green's functions. In particular, we focus on the spin\nresolved conductance, magnetoresistance and current-voltage curves. A\n5-atom-ring is formed in MVs, a 5-8-5 ring structure in DVs, and a 8-4-8-4 ring\nstructure in LVs. The linear conductance becomes strongly spin dependent when\nthe transversal symmetry is broken by vacancies especially if they are located\non the ribbon's edges. The giant magnetoresistance can be smeared by asymmetric\nvacancies. Single spin negative differential resistance may appear in the\npresence of LVs and asymmetric MVs or DVs. A strong spin Seebeck effect is\nexpected at room temperature in ZSiNRs with LVs."
    },
    {
        "anchor": "Damped spin-wave excitations in the itinerant antiferromagnet\n  $\u03b3$-Fe$_{0.7}$Mn$_{0.3}$: The collective spin-wave excitations in the antiferromagnetic state of\n$\\gamma$-Fe$_{0.7}$Mn$_{0.3}$ were investigated using the inelastic neutron\nscattering technique. The spin excitations remain isotropic up to the high\nexcitation energy, ${\\hbar\\omega}= 78$ meV. The excitations gradually become\nbroad and damped above 40 meV. The damping parameter ${\\gamma}$ reaches 110(16)\nmeV at ${\\hbar\\omega} = 78$ meV, which is much larger than that for other\nmetallic compounds, e.g., CaFe$_2$As$_2$ (24 meV),\nLa$_{2-2x}$Sr$_{1+2x}$Mn$_2$O$_7$ ($52-72$ meV), and Mn$_{90}$Cu$_{10}$ (88\nmeV). In addition, the spin-wave dispersion shows a deviation from the relation\n$({\\hbar\\omega})^2 = c^2q^2 + {\\Delta}^2$ above 40 meV. The group velocity\nabove this energy increases to 470(40) meV{\\AA}, which is higher than that at\nthe low energies, $c = 226(5)$ meV{\\AA}. These results could suggest that the\nspin-wave excitations merge with the continuum of the individual particle-hole\nexcitations at 40 meV.",
        "positive": "Thermal conductivity of graphene polymorphs and compounds: from C3N to\n  graphdiyne lattices: Tremendous experimental and theoretical attempts to find carbon based\ntwo-dimensional semiconductors have yielded a wide variety of graphene\npolymorphs, such as carbon-nitride, carbonboride, graphyne and graphdiyne 2D\nmaterials with highly attractive physical and chemical properties. In this\nstudy, by conducting extensive non-equilibrium molecular dynamics simulations,\nwe have calculated and compared the thermal conductivity of thirteen prominent\ncarbon-based structures at different lengths and two main chirality directions.\nAcquired results show that the structures of C3N, C3B and C2N exhibit the\nhighest thermal conductivity, respectively, which suggest them as suitable\ncandidates for thermal management systems in order to enhance the heat\ndissipation rates. In contrast, generally graphdiyne lattices and in particular\n18-6-Gdy graphdiyne yields the lowest thermal conductivity, which can be a\npromising feature for thermoelectric applications. As a remarkable finding, we\ncould establish connections between the thermal conductivity and density or\nYoung's modulus of carbon based 2D systems, which can be employed to estimate\nthe thermal conductivity of other polymorphs. Those results can provide a\ncomprehensive viewpoint on the thermal transport properties of the nonporous\nand exceedingly porous carbon based 2D materials and may be used as useful\nguides for future designs in thermal management."
    },
    {
        "anchor": "X-ray photoelectron spectroscopy, Raman and photoluminescence studies on\n  formation of defects in Cu:ZnO thin films and its role in non-linear optical\n  features: The structural, optical, morphological and nonlinear optical properties of\nCu:ZnO spray-coated films are studied. The surface morphology of Cu:ZnO thin\nfilms turned out to be homogenous, crack free and well covered with pea-shaped\ngrains. The peak shift observed in the x-ray photoelectron spectroscopy spectra\nof the Cu:ZnO thin films infers the defect states present in the films. The\nsatellite peak observed at 939.9 eV for Cu2P core-level spectra confirms the +2\noxidation state of Cu in the films. The formation of additional defect levels\nin the nanostruc-tures upon Cu doping was investigated using photoluminescence\n(PL) and Raman spectroscopy studies. The luminescent centers in the violet,\nblue and green spectral region were observed. The most prominent emission was\ncentered at the blue color center for 5% Cu:ZnO thin films. The en-hancement in\nthe PL emission intensity confirms the increase in the defect state density\nupon Cu doping. The shifting of the UV emission peak to the visible region\nvalidates the increase in the non-radiative recombination process in the films\nupon doping. The phonon modes observed in Raman analysis around 439, 333 and\n558 cm-1 confirm the improvement in the crystallinity and formation of defect\nstates in the films. X-ray diffraction reveals that the deposited films are of\nsingle-phase wurtzite ZnO structure with preferential growth orientation\nparallel (0 0 2) to the C-axis. The third-order optical susceptibility\n\\c{hi}(3) has been increased from 3.5 x 10-4 to 2.77 x 10-3 esu due to the\nenhancement of electronic transition to different defect levels formed in the\nfilms and through local heating effects arising due to continuous wave laser\nillumination. The enhanced third harmonic generation signal investigated using\na Nd:YAG laser at 1064 nm and 8 ns pulse width shows the credibility of Cu:ZnO\nfilms in frequency tripling applications.",
        "positive": "Boundary conditions for spin diffusion: We develop a general scheme of deriving boundary conditions for spin-charge\ncoupled transport in disordered systems with spin-orbit interactions. To\nillustrate the application of the method, we explicitly derive boundary\nconditions for spin diffusion in the Rashba model. Due to the surface spin\nprecession, the boundary conditions are non-trivial and contain terms, which\ncouple different components of the spin density. We argue that boundary\nconditions and the corresponding electric-field-induced spin accumulation\ngenerally depend on the nature of the boundary and therefore the spin Hall\neffect in a spin-orbit coupled system can be viewed as a non-universal edge\nphenomenon."
    },
    {
        "anchor": "Robust Magnetoelectric Effect in Decorated Graphene/In2Se3\n  Heterostructure: Magnetoelectric effect is a fundamental physics phenomenon that synergizes\nelectric and magnetic degrees of freedom to generate distinct material\nresponses like electrically tuned magnetism, which serves as a key foundation\nof the emerging field of spintronics. Here, we show by first-principles studies\nthat ferroelectric (FE) polarization of an In2Se3 monolayer can modulate the\nmagnetism of an adjacent transition-metal (TM) decorated graphene layer via an\nFE induced electronic transition. The TM nonbonding d-orbital shifts downward\nand hybridizes with carbon p states near the Fermi level, suppressing the\nmagnetic moment, under one FE polarization, but on reversed FE polarization\nthis TM d-orbital moves upward, restoring the original magnetic moment. This\nfinding of robust magnetoelectric effect in TM decorated graphene/In2Se3\nheterostructure offers powerful insights and a promising avenue for\nexperimental exploration of FE controlled magnetism in 2D materials.",
        "positive": "Multiple types of topological fermions in transition metal silicides: Exotic massless fermionic excitations with non-zero Berry flux, other than\nDirac and Weyl fermions, could exist in condensed matter systems under the\nprotection of crystalline symmetries, such as spin-1 excitations with 3-fold\ndegeneracy and spin-3/2 Rarita-Schwinger-Weyl fermions. Herein, by using ab\ninitio density functional theory, we show that these unconventional\nquasiparticles coexist with type-I and type-II Weyl fermions in a family of\ntransition metal silicides, including CoSi, RhSi, RhGe and CoGe, when the\nspin-orbit coupling (SOC) is considered. Their non-trivial topology results in\na series of extensive Fermi arcs connecting projections of these bulk\nexcitations on side surface, which is confirmed by (010) surface electronic\nspectra of CoSi. In addition, these stable arc states exist within a wide\nenergy window around the Fermi level, which makes them readily accessible in\nangle-resolved photoemission spectroscopy measurements."
    },
    {
        "anchor": "Janus icosahedral particles: amorphization driven by three-dimensional\n  atomic misfit and edge dislocation compensation: Icosahedral nanoparticles composed of fivefold twinned tetrahedra have broad\napplications. The strain relief mechanism and angular deficiency in icosahedral\nmultiply twinned particles are poorly understood in three dimensions. Here, we\nresolved the three-dimensional atomic structures of Janus icosahedral\nnanoparticles using atomic resolution electron tomography. A geometrically\nfivefold face consistently corresponds to a less ordered face like two\nhemispheres. We quantify rich structural variety of icosahedra including bond\norientation order, bond length, strain tensor; and packing efficiency, atom\nnumber, solid angle of each tetrahedron. These structural characteristics\nexhibit two-sided distribution. Edge dislocations near the axial atoms and\nsmall disordered domains fill the angular deficiency. Our findings provide new\ninsights how the fivefold symmetry can be compensated and the\ngeometrically-necessary internal strains relived in multiply twinned particles.",
        "positive": "Quantitative analysis of spectroscopic Low Energy Electron Microscopy\n  data: High-dynamic range imaging, drift correction and cluster analysis: For many complex materials systems, low-energy electron microscopy (LEEM)\noffers detailed insights into morphology and crystallography by naturally\ncombining real-space and reciprocal-space information. Its unique strength,\nhowever, is that all measurements can easily be performed energy-dependently.\nConsequently, one should treat LEEM measurements as multi-dimensional,\nspectroscopic datasets rather than as images to fully harvest this potential.\nHere we describe a measurement and data analysis approach to obtain such\nquantitative spectroscopic LEEM datasets with high lateral resolution. The\nemployed detector correction and adjustment techniques enable measurement of\ntrue reflectivity values over four orders of magnitudes of intensity. Moreover,\nwe show a drift correction algorithm, tailored for LEEM datasets with inverting\ncontrast, that yields sub-pixel accuracy without special computational demands.\nFinally, we apply dimension reduction techniques to summarize the key\nspectroscopic features of datasets with hundreds of images into two single\nimages that can easily be presented and interpreted intuitively. We use cluster\nanalysis to automatically identify different materials within the field of view\nand to calculate average spectra per material. We demonstrate these methods by\nanalyzing bright-field and dark-field datasets of few-layer graphene grown on\nsilicon carbide and provide a high-performance Python implementation."
    },
    {
        "anchor": "Small electron polarons bound to interstitial tantalum defects in\n  lithium tantalate: The absorption features of optically generated, short-lived small bound\nelectron polarons are inspected in congruent lithium tantalate, LiTaO$_3$ (LT),\nin order to address the question whether it is possible to localize electrons\nat interstitial Ta$_{\\rm V}$:V$_{\\rm Li}$ defect pairs by strong, short-range\nelectron-phonon coupling. Solid-state photoabsorption spectroscopy under light\nexposure and density functional theory are used for an experimental and\ntheoretical access to the spectral features of small bound polaron states and\nto calculate the binding energies of the small bound Ta$_{\\rm Li}^{4+}$\n(antisite) and Ta$_{\\rm V}^{4+}$:V$_{\\rm Li}$ (interstitial site) electron\npolarons. As a result, two energetically well separated ($\\Delta E \\approx 0.5$\neV) absorption features with a distinct dependence on the probe light\npolarization and peaking at 1.6 eV and 2.1 eV are discovered. We contrast our\nresults to the interpretation of a single small bound Ta$_{\\rm Li}^{4+}$\nelectron state with strong anisotropy of the lattice distortion and discuss the\noptical generation of interstitial Ta$_{\\rm V}^{4+}$:V$_{\\rm Li}$ small\npolarons in the framework of optical gating of Ta$_{\\rm V}^{4+}$:Ta$_{\\rm\nTa}^{4+}$ bipolarons. We can conclude that the appearance of carrier\nlocalization at Ta$_{\\rm V}$:V$_{\\rm Li}$ must be considered as additional\nintermediate state for the 3D hopping transport mechanisms at room temperature\nin addition to Ta$_{\\rm Li}$, as well, and, thus, impacts a variety of optical,\nphotoelectrical and electrical applications of LT in nonlinear photonics.\nFurthermore, it is envisaged that LT represents a promising model system for\nthe further examination of the small-polaron based photogalvanic effect in\npolar oxides with the unique feature of two, energetically well separated small\npolaron states.",
        "positive": "Quantum Conductance Probing of Oxygen Vacancies in SrTiO3 Epitaxial Thin\n  Film Using Graphene: The quantum Hall conductance in monolayer graphene on an epitaxial SrTiO3\n(STO) thin film is studied to understand the role of oxygen vacancies in\ndetermining the dielectric properties of STO. As the gate voltage sweep range\nis gradually increased in our device, we observe systematic generation and\nannihilation of oxygen vacancies evidenced from the hysteretic conductance\nbehavior in graphene. Furthermore, based on the experimentally observed linear\nscaling relation between the effective capacitance and the voltage sweep range,\na simple model is constructed to manifest the relationship among the dielectric\nproperties of STO with oxygen vacancies. The inherent quantum Hall conductance\nin graphene can be considered as a sensitive, robust, and non-invasive probe\nfor understanding the electronic and ionic phenomena in complex transition\nmetal oxides without impairing the oxide layer underneath."
    },
    {
        "anchor": "An Exactly Solvable Phase-Field Theory of Dislocation Dynamics, Strain\n  Hardening and Hysteresis in Ductile Single Crystals: An exactly solvable phase-field theory of dislocation dynamics, strain\nhardening and hysteresis in ductile single crystals is developed. The theory\naccounts for: an arbitrary number and arrangement of dislocation lines over a\nslip plane; the long-range elastic interactions between dislocation lines; the\ncore structure of the dislocations resulting from a piecewise quadratic Peierls\npotential; the interaction between the dislocations and an applied resolved\nshear stress field; and the irreversible interactions with short-range\nobstacles and lattice friction, resulting in hardening, path dependency and\nhysteresis. A chief advantage of the present theory is that it is analytically\ntractable, in the sense that the complexity of the calculations may be reduced,\nwith the aid of closed form analytical solutions, to the determination of the\nvalue of the phase field at point-obstacle sites. In particular, no numerical\ngrid is required in calculations. The phase-field representation enables\ncomplex geometrical and topological transitions in the dislocation ensemble,\nincluding dislocation loop nucleation, bow-out, pinching, and the formation of\nOrowan loops. The theory also permits the consideration of obstacles of varying\nstrengths and dislocation line-energy anisotropy. The theory predicts a range\nof behaviors which are in qualitative agreement with observation, including:\nhardening and dislocation multiplication in single slip under monotonic\nloading; the Bauschinger effect under reverse loading; the fading memory\neffect, whereby reverse yielding gradually eliminates the influence of previous\nloading; the evolution of the dislocation density under cycling loading,\nleading to characteristic `butterfly' curves; and others.",
        "positive": "A Recipe for Composite Materials: An Approach through Fiber Bundle Model: Strengthening of materials and preventing abrupt fracture are really\nchallenging jobs in the field of engineering and material science. Such\nproblems can be resolved by using composite materials. In this work, we have\nstudied the fracture process of a composite material in light of fiber bundle\nmodel with different elastic constants as well as different random threshold\nbreaking strength of fibers. The critical width of the threshold distribution\n($\\delta_c$), for which abrupt failure occurs, is studied both analytically and\nnumerically with increasing number of components $(k)$ in the composite and it\nis shown that $\\delta_c$ is inversely related to $k$. Corresponding phase\ndiagram for the model suggests decrease in the tendency of abrupt fracture as\nnumber of components in the composite increase."
    },
    {
        "anchor": "Minimum free-energy path of homogenous nucleation from the phase-field\n  equation: The minimum free-energy path (MFEP) is the most probable route of the\nnucleation process on the multidimensional free-energy surface. In this study,\nthe phase-field equation is used as a mathematical tool to deduce the minimum\nfree-energy path (MFEP) of homogeneous nucleation. We use a simple\nsquare-gradient free-energy functional with a quartic local free-energy\nfunction as an example and study the time evolution of a single nucleus placed\nwithin a metastable environment. The time integration of the phase-field\nequation is performed using the numerically efficient cell-dynamics method. By\nmonitoring the evolution of the size of the nucleus and the free energy of the\nsystem simultaneously, we can easily deduce the free-energy barrier as a\nfunction of the size of the sub- and the super-critical nucleus along the MFEP.",
        "positive": "Graphene formation on SiC substrates: Graphene layers were created on both C and Si faces of semi-insulating,\non-axis, 4H- and 6H-SiC substrates. The process was performed under high vacuum\n(<10-4 mbar) in a commercial chemical vapor deposition SiC reactor. A method\nfor H2 etching the on-axis sub-strates was developed to produce surface steps\nwith heights of 0.5 nm on the Si-face and 1.0 to 1.5 nm on the C-face for each\npolytype. A process was developed to form graphene on the substrates\nimmediately after H2 etching and Raman spectroscopy of these samples confirmed\nthe formation of graphene. The morphology of the graphene is described. For\nboth faces, the underlying substrate morphology was significantly modified\nduring graphene formation; sur-face steps were up to 15 nm high and the uniform\nstep morphology was sometimes lost. Mo-bilities and sheet carrier\nconcentrations derived from Hall Effect measurements on large area (16 mm\nsquare) and small area (2 and 10 um square) samples are presented and shown to\ncompare favorably to recent reports."
    },
    {
        "anchor": "First Principles Calculation of Field Emission from Carbon Nanotubes\n  With Nitrogen and Boron Doping: We investigate the field emission properties of nitrogenated and boronated\ncarbon nanotubes using time-dependent density functional theory, were the wave\nfunction propagation is performed using the Crank-Nicholson algorithm. We\nextract the current-voltage characteristics of the emitted electrons from\nnanotubes with different doping configurations. We found that boron doping\neither impedes, or slightly enhances, field emission. Nitrogen strongly\ninfluences the emission current, and the current is sensitive to the location\nof the nitrogen dopant in the nanotube. The emitted charge cloud from nitrogen\ndoped carbon nanotubes is, however, more diffuse than that from pristine ones,\nour simulations show the emergence of a branching from the charge cloud, making\nnitrogenated carbon nanotubes less convenient for use in narrow beam\napplications.",
        "positive": "Insights of Dielectric relaxations in Nd and Mn co-substituted BiFeO3: The composition-driven structural transition from the R3c to Pbnm symmetry\nwas observed. Highest dielectric constant was observed for\nBi0.95Nd0.05Fe0.95Mn0.05O3. Conductivity can be explained by the small polaron\nhopping model. The non-Debye type of dielectric relaxation is observed. The\ndielectric anomaly at the magnetic transition temperature is evident."
    },
    {
        "anchor": "Synthesis and structural characterization of Sb-doped TiFe2Sn Heusler\n  compounds: Heusler compounds form a numerous class of intermetallics, which include two\nfamilies of compositions ABC and AB2C, usually referred to as half- and\nfull-Heusler compounds, respectively. Given their tunable electronic\nproperties, made possible by adjusting the chemical composition, these\nmaterials are currently considered for the possible use in sustainable\ntechnologies such as solar energy and thermoelectric conversion. According to\ntheoretical predictions, Sb substitution in the TiFe2Sn full-Heusler compound\nis thought to yield band structure modifications that should enhance the\nthermoelectric power factor. In this work we tested the phase stability and the\nstructural and microstructural properties of such heavily-doped compounds. We\nsynthesized polycrystalline TiFe2Sn1-xSbx samples (x=0,0.1,0.2 and 1.0) by arc\nmelting, followed annealing. The structural characterization, performed by\nx-ray powder diffraction and microscopy analyses, confirmed the formation of\nthe Heusler AB2C structure (cF16, Fm-3m, prototype: MnCu2Al) in all samples,\nwith only few percent amounts of secondary phases and only slight deviations\nfrom nominal stoichiometry. With increasing Sb substitution we found a steady\ndecrease of the lattice parameter, confirming that the replacement takes place\nat the Sn site. Quite unusually, the as cast samples exhibited a higher lattice\ncontraction than the annealed ones. The fully substituted x=1.0 compound, again\nadopting the MnCu2Al structure, does not form as stoichiometric phase and\nturned out to be strongly Fe deficient.The physical behavior at room\ntemperature indicated that annealing with increasing temperature is beneficial\nfor electrical and thermoelectrical transport. Moreover, we measured a slight\nimprovement of electrical and thermoelectrical properties in the x=0.1 sample\nand a suppression in the x=0.2 sample, as compared to the undoped x=0 sample.",
        "positive": "Massive Dirac fermions in a ferromagnetic kagome metal: The kagome lattice is a two-dimensional network of corner-sharing triangles\nknown as a platform for exotic quantum magnetic states. Theoretical work has\npredicted that the kagome lattice may also host Dirac electronic states that\ncould lead to topological and Chern insulating phases, but these have evaded\nexperimental detection to date. Here we study the d-electron kagome metal\nFe$_3$Sn$_2$ designed to support bulk massive Dirac fermions in the presence of\nferromagnetic order. We observe a temperature independent intrinsic anomalous\nHall conductivity persisting above room temperature suggestive of prominent\nBerry curvature from the time-reversal breaking electronic bands of the kagome\nplane. Using angle-resolved photoemission, we discover a pair of quasi-2D Dirac\ncones near the Fermi level with a 30 meV mass gap that accounts for the Berry\ncurvature-induced Hall conductivity. We show this behavior is a consequence of\nthe underlying symmetry properties of the bilayer kagome lattice in the\nferromagnetic state with atomic spin-orbit coupling. This report provides the\nfirst evidence for a ferromagnetic kagome metal and an example of emergent\ntopological electronic properties in a correlated electron system. This offers\ninsight into recent discoveries of exotic electronic behavior in kagome lattice\nantiferromagnets and may provide a stepping stone toward lattice model\nrealizations of fractional topological quantum states."
    },
    {
        "anchor": "NC-AFM and XPS Investigation of Single-crystal Surfaces Supporting\n  Cobalt (III) Oxide Nanostructures Grown by a Photochemical Method: The work of this thesis comprises extensive Noncontact Atomic Force\nMicroscopy (NC-AFM) characterization of clean metal-oxide (YSZ(100)/(111) and\nMgO(100)) and graphitic (HOPG) supports as templates for the novel,\nphotochemically induced nucleation of cobalt oxide nanostructures, particularly\nCobalt (III) Oxide. The nanostructure-support surfaces were also studied by\nX-ray Photoelectron Spectroscopy (XPS) to verify the nature of the supported\ncobalt oxide and to corroborate the surface topographic and phase NC-AFM data.\nHeteroepitaxial growth of Co2O3 nanostructures proves to exhibit a variety of\ndifferent growth modes based on the structure of the support surface. On this\nbasis, single-crystal support surfaces ranging from nonpolar to polar and\natomically flat to highly defective and reactive were chosen, again, yielding\nnumerous substrate-nanostructure interactions that could be probed by\nhigh-performance surface science techniques.",
        "positive": "Orientation-dependent deformation mechanisms of bcc niobium\n  nanoparticles: Nanoparticles usually exhibit pronounced anisotropic properties, and a close\ninsight into the atomic-scale deformation mechanisms is of great interest. In\npresent study, atomic simulations are conducted to analyze the compression of\nbcc nanoparticles, and orientation-dependent features are addressed. It is\nrevealed that surface morphology under indenter predominantly governs the\ninitial elastic response. The loading curve follows the flat punch contact\nmodel in [110] compression, while it obeys the Hertzian contact model in [111]\nand [001] compressions. In plastic deformation regime, full dislocation gliding\nis dominated in [110] compression, while deformation twinning is prominent in\n[111] compression, and these two mechanisms coexist in [001] compression. Such\ndeformation mechanisms are distinct from those in bulk crystals under\nnanoindentation and nanopillars under compression, and the major differences\nare also illuminated. Our results provide an atomic perspective on the\nmechanical behaviors of bcc nanoparticles and are helpful for the design of\nnanoparticle-based components and systems."
    },
    {
        "anchor": "Weyl nodes and magnetostructural instability in antiperovskite Mn$_3$ZnC: The ferromagnetic phase of the cubic antiperovskite Mn$_3$ZnC is suggested\nfrom first-principles calculation to be a nodal line Weyl semimetal. Features\nin the electronic structure that are the hallmark of a nodal line Weyl state, a\nlarge density of linear band crossings near the Fermi level, can also be\ninterpreted as signatures of a structural and/or magnetic instability. Indeed,\nit is known that Mn$_3$ZnC undergoes transitions upon cooling from a\nparamagnetic to a cubic ferromagnetic state under ambient conditions and then\nfurther into a non-collinear ferrimagnetic tetragonal phase at a temperature\nbetween 250$\\,$K and 200$\\,$K. The existence of Weyl nodes and their\ndestruction via structural and magnetic ordering is likely to be relevant to a\nrange of magnetostructurally coupled materials.",
        "positive": "Growth and texture of Spark Plasma Sintered Al2O3 ceramics: a combined\n  analysis of X-rays and Electron Back Scatter Diffraction: Textured alumina ceramics were obtained by Spark Plasma Sintering (SPS) of\nundoped commercial a-Al2O3 powders. Various parameters (density, grain growth,\ngrain size distribution) of the alumina ceramics, sintered at two typical\ntemperatures 1400{\\deg}C and 1700{\\deg}C, are investigated. Quantitative\ntextural and structural analysis, carried out using a combination of Electron\nBack Scattering Diffraction (EBSD) and X-ray diffraction (XRD), are represented\nin the form of mapping, and pole figures. The mechanical properties of these\ntextured alumina ceramics include high elastic modulus and hardness value with\nhigh anisotropic nature, opening the door for a large range of applications"
    },
    {
        "anchor": "Converse flexoelectricity around ferroelastic domain walls: Domain walls (DWs) are ubiquitous in ferroelectric materials. Ferroelastic\nDWs refer to those who separate two domains with unparalleled polarizations (or\ntwo different ferroelastic variants). It is long believed that the structures\nof ferroelastic DWs can be simply explained from the perspective of mechanical\nand electric compatibilities in the framework of the Landau-Ginzburg-Devonshire\n(LGD) theory. Here we show that the converse flexoelectricity must be taken\ninto account for fully describing the nature of ferroelastic DWs. In our work,\nan unexpected asymmetric structure is identified, which is beyond the\nprediction of the conventional LGD theory. By incorporating the converse\nflexoelectricity into the LGD theory and using it to analyze high-resolution\nimages acquired by the aberration-corrected transmission electron microscope\n(TEM), we demonstrate that it is the converse flexoelectricity that result in\nthe asymmetric structure. Moreover, the flexoelectric coefficient is derived by\nquantifying the converse flexoelectricity around the DWs. This quantification\nis deterministic in both the magnitude and sign of flexoelectric coefficients,\nby the mutual verification of atomic mapping and first-principles calculations.\nOur results suggest that the converse flexoelectricity cannot be neglected for\nunderstanding the ferroelastic DWs and other boundaries in ferroelectric\nmaterials.",
        "positive": "Reconstruction of densities from Compton profiles with applying Jacobi\n  polynomials: The advent of synchrotron sources has led to an increasing availability of\nhigh resolution Compton Profiles J(pz) and a consequent renewed interest in the\nreconstruction of the corresponding full momentum densities rho(p).\n  We present results of applying a new method in which the radial parts of\nrho(p) and the measured profiles are expressed in terms of Jacobi polynomials.\nThe technique is demonstrated using model projections that correspond to Mg and\nGd spectra. Reconstructed densities, being in very good agreement with model\nones, are a very good performance of our new reconstruction algorithm."
    },
    {
        "anchor": "In situ studies of evolution of microstructure with temperature in\n  heavily deformed Ti-modified austenitic stainless steel by X-ray Diffraction\n  technique: The mechanism of the evolution of the deformed microstructure at the earliest\nstage of annealing where the existence of the lowest length scale substructure\npaves the way to the formation of the so-called subgrains, has been studied for\nthe first time. The study has been performed at high temperature on heavily\ndeformed Ti-modified austenitic stainless steel using X-ray diffraction\ntechnique. Significant changes were observed in the values of the domain size,\nboth with time and temperature. Two different types of mechanism have been\nproposed to be involved during the microstructural evolution at the earliest\nstages of annealing. The nature of the growth of domains with time at different\ntemperatures has been modelled using these mechanisms. High-resolution\ntransmission electron microscopy has been used to view the microstructure of\nthe deformed and annealed sample and the results have been corroborated\nsuccessfully with those found from the X-ray diffraction techniques.",
        "positive": "Creation of high mobility two-dimensional electron gases via strain\n  induced polarization at an otherwise nonpolar complex oxide interface: The discovery of two-dimensional electron gases (2DEGs) in SrTiO3-based\nheterostructures provides new opportunities for nanoelectronics. Herein, we\ncreate a new type of oxide 2DEG by the epitaxial-strain-induced polarization at\nan otherwise nonpolar perovskite-type interface of CaZrO3/SrTiO3. Remarkably,\nthis heterointerface is atomically sharp, and exhibits a high electron mobility\nexceeding 60,000 cm2V-1s-1 at low temperatures. The 2DEG carrier density\nexhibits a critical dependence on the film thickness, in good agreement with\nthe polarization induced 2DEG scheme."
    },
    {
        "anchor": "Confinement Effect Emission from Infiltrated ZnO in PS-b-PMMA\n  Nanostructures: We have characterized the growth of ZnO using sequential infiltration\nsynthesis (SiS) on PS-b-PMMA block copolymers (BCP) of spherical and\ncylindrical sub-20nm morphologies and studied how the photoluminescence of\nthese nanostructures varies per its seed layer. Investigation of these\nstructures was done using atomic force microscopy (AFM), spectrofluorometry,\nRaman spectroscopy, and scanning electron microscopy (SEM). We report\nblue-shifted photoemission at 335 nm (3.70 eV), suggesting quantum confinement\neffects. This UV-photoluminescence can be translated into emitter sizes of\nroughly 1.5nm in radius. Furthermore, samples of ZnO prepared with an alumina\nseed layer showed additional defect state photoemission at 470 nm and 520 nm\nfor spherical and cylindrical BCP morphologies, respectively. Defect\nphotoemission was not observed in samples prepared without a seed layer. Raman\nand EXAFS data suggest lack of long range order between the ZnO nanostructures\nduring early stages of infiltrated ZnO growth and therefore supports the blue\nshift emission is due to confinement. Our work demonstrates that ZnO\nnanostructures grown on PS-b-PMMA via infiltration are advantageous in\nuniformity and size, and exhibit unique fluorescence properties. These\nobservations suggest that infiltrated ZnO in PS-b-PMMA nanostructures lends\nitself to a new regime of applications in photonics and quantum materials.",
        "positive": "Resonance Raman spectroscopy of silicene and germanene: We model Raman processes in silicene and germanene involving scattering of\nquasiparticles by, either, two phonons, or, one phonon and one point defect. We\ncompute the resonance Raman intensities and lifetimes for laser excitations\nbetween 1 and 3$\\,$eV using a newly developed third-nearest neighbour\ntight-binding model parametrized from first principles density functional\ntheory. We identify features in the Raman spectra that are unique to the\nstudied materials or the defects therein. We find that in silicene, a new Raman\nresonance arises from the $2.77\\,\\rm$eV $\\pi-\\sigma$ plasmon at the M point,\nmeasurably higher than the Raman resonance originating from the $2.12\\,\\rm$eV\n$\\pi$ plasmon energy. We show that in germanene, the lifetimes of charge\ncarriers, and thereby the linewidths of the Raman peaks, are influenced by\nspin-orbit splittings within the electronic structure. We use our model to\npredict scattering cross sections for defect induced Raman scattering involving\nadatoms, substitutional impurities, Stone-Wales pairs, and vacancies, and argue\nthat the presence of each of these defects in silicene and germanene can be\nqualitatively matched to specific features in the Raman response."
    },
    {
        "anchor": "Intermediate Polaronic Charge Transport in Organic Crystals from a\n  Many-Body First-Principles Approach: Predicting the electrical properties of organic molecular crystals (OMCs) is\nchallenging due to their complex crystal structures and electron-phonon (e-ph)\ninteractions. Charge transport in OMCs is conventionally categorized into two\nlimiting regimes $-$ band transport, characterized by weak e-ph interactions,\nand charge hopping due to localized polarons formed by strong e-ph\ninteractions. However, between these two limiting cases there is a less well\nunderstood intermediate regime where polarons are present but transport does\nnot occur via hopping. Here we show a many-body first-principles approach that\ncan accurately predict the carrier mobility in OMCs in the intermediate regime\nand shed light on its microscopic origin. Our approach combines a\nfinite-temperature cumulant method to describe strong e-ph interactions with\nGreen-Kubo transport calculations. We apply this parameter-free framework to\nnaphthalene crystal, demonstrating electron mobility predictions within a\nfactor of 1.5$-$2 of experiment between 100$-$300 K. Our analysis reveals that\nelectrons couple strongly with both inter- and intramolecular phonons in the\nintermediate regime, as evidenced by the formation of a broad polaron satellite\npeak in the electron spectral function and the failure of the Boltzmann\nequation. Our study advances quantitative modeling of charge transport in\ncomplex organic crystals.",
        "positive": "Spin- and angle-resolved photoemission studies of the electronic\n  structure of Si(110)\"16x2\" surfaces: The electronic structure of Si(110)\"16 x 2\" double-domain, single-domain and\n1 x 1 surfaces have been investigated using spin- and angle-resolved\nphotoemission at sample temperatures of 77 K and 300 K. Angle-resolved\nphotoemission was conducted using horizontally- and vertically-polarised 60 eV\nand 80 eV photons. Band-dispersion maps revealed four surface states ($S_1$ to\n$S_4$) which were assigned to silicon dangling bonds on the basis of measured\nbinding energies and photoemission intensity changes between horizontal and\nvertical light polarisations. Three surface states ($S_1$, $S_2$ and $S_4$),\nobserved in the Si(110)\"16 x 2\" reconstruction, were assigned to Si adatoms and\nSi atoms present at the edges of the corrugated terrace structure. Only one of\nthe four surface states, $S_3$, was observed in both the Si(110)\"16 x 2\" and 1\nx 1 band maps and consequently attributed to the pervasive Si zigzag chains\nthat are components of both the Si(110)\"16 x 2\" and 1 x 1 surfaces. A state in\nthe bulk-band region was attributed to an in-plane bond. All data were\nconsistent with the adatom-buckling model of the Si(110)\"16 x 2\" surface.\nWhilst room temperature measurements of $P_y$ and $P_z$ were statistically\ncompatible with zero, $P_x$ measurements of the enantiomorphic A-type and\nB-type Si(110)\"16 x 2\" surfaces gave small average polarisations of around\n1.5\\% that were opposite in sign. Further measurements at 77 K on A-type\nSi(110)\"16 x 2\" surface gave a smaller value of +0.3\\%. An upper limit of\n$\\sim1\\%$ may thus be taken for the longitudinal polarisation."
    },
    {
        "anchor": "Normal modes, and acoustic properties, of an elastic solid with line\n  defects: The normal modes of a continuum solid endowed with a random distribution of\nline defects that behave like elastic strings are described. These strings\ninteract with elastic waves in the bulk, generating wave dispersion and\nattenuation. As in amorphous materials, the attenuation as a function of\nfrequency $\\omega$ behaves as $\\omega^4$ for low frequencies, and, as frequency\nincreases, crosses over to $\\omega^2$ and then to linear in $\\omega$.\nDispersion is negative in the frequency range where attenuation is quartic and\nquadratic in frequency. Explicit formulae are provided that relate these\nproperties to the density of string states. { Continuum mechanics can thus be\napplied both to crystalline materials and their amorphous counterparts at\nsimilar length scales.} The possibility of linking this model with the\nmicrostructure of amorphous materials is discussed.",
        "positive": "Elastic dipole tensors and relaxation volumes of point defects in\n  concentrated random magnetic Fe-Cr alloys: Point defects in body-centred cubic Fe, Cr and concentrated random magnetic\nFe-Cr are investigated using density functional theory and theory of\nelasticity. The volume of a substitutional Cr atom in ferromagnetic bcc Fe is\napproximately 18\\% larger than the volume of a host Fe atom, whereas the volume\nof a substitutional Fe atom in antiferromagnetic bcc Cr is 5\\% smaller than the\nvolume of a host Cr atom. Elastic dipole $\\boldsymbol{P}$ and relaxation volume\n$\\boldsymbol{\\Omega}$ tensors of vacancies and self-interstitial atom (SIA)\ndefects exhibit large fluctuations, with vacancies having negative and SIA\nlarge positive relaxation volumes. Dipole tensors of vacancies are nearly\nisotropic across the entire alloy composition range, with diagonal elements\n$P_{ii}$ decreasing as a function of Cr content. Fe-Fe and Fe-Cr SIA dumbbells\nare more anisotropic than Cr-Cr dumbbells. Fluctuations of elastic dipole\ntensors of SIA defects are primarily associated with the variable\ncrystallographic orientations of the dumbbells. Statistical properties of\ntensors $\\boldsymbol{P}$ and $\\boldsymbol{\\Omega}$ are analysed using their\nprincipal invariants, suggesting that point defects differ significantly in\nalloys containing below and above 10\\% at. Cr. The relaxation volume of a\nvacancy depends sensitively on whether it occupies a Fe or a Cr lattice site. A\ncorrelation between elastic relaxation volumes and magnetic moments of defects\nfound in this study suggests that magnetism is a significant factor influencing\nelastic fields of defects in Fe-Cr alloys."
    },
    {
        "anchor": "First-principles study of defects at $\\Sigma3$ grain boundaries in\n  CuGaSe$_2$: We present a first-principles computational study of cation-Se $\\Sigma$3\n(112) grain boundaries in CuGaSe$_2$. We discuss the structure of these grain\nboundaries, as well as the effect of native defects and Na impurities on their\nelectronic properties. The formation energies show that the defects will tend\nto form preferentially at the grain boundaries, rather than in the grain\ninteriors. We find that in Ga-rich growth conditions Cu vacancies as well as Ga\nat Cu and Cu at Ga antisites are mainly responsible for having the equilibrium\nFermi level pinned toward the middle of the gap, resulting in carrier\ndepletion. The Na at Cu impurity in its +1 charge state contributes to this. In\nGa-poor growth conditions, on the other hand, the formation energies of Cu\nvacancies and Ga at Cu antisites are comparatively too high for any significant\ninfluence on carrier density or on the equilibrium Fermi level position. Thus,\nunder these conditions, the Cu at Ga antisites give rise to a $p$-type grain\nboundary. Also, their formation energy is lower than the formation energy of Na\nat Cu impurities. Thus, the latter will fail to act as a hole barrier\npreventing recombination at the grain boundary, in contrast to what occurs in\nCuInSe$_2$ grain boundaries. We also discuss the effect of the defects on the\nelectronic properties of bulk CuGaSe$_2$, which we assume reflect the\nproperties of the grain interiors.",
        "positive": "Point defect formation energies in graphene from diffusion quantum Monte\n  Carlo and density functional theory: Density functional theory (DFT) is widely used to study defects in monolayer\ngraphene with a view to applications ranging from water filtration to\nelectronics to investigation of radiation damage in graphite moderators. To\nassess the accuracy of DFT in such applications, we report diffusion quantum\nMonte Carlo (DMC) calculations of the formation energies of some common and\nimportant point defects in monolayer graphene: monovacancies, Stone-Wales\ndefects, and silicon substitutions. We find that standard DFT methods\nunderestimate monovacancy formation energies by around 1 eV. The disagreement\nbetween DFT and DMC is somewhat smaller for Stone-Wales defects and silicon\nsubstitutions. We examine vibrational contributions to the free energies of\nformation for these defects, finding that vibrational effects are\nnon-negligible. Finally, we compare the DMC atomization energies of monolayer\ngraphene, monolayer silicene, and bulk silicon, finding that bulk silicon is\nsignificantly more stable than monolayer silicene by 0.7522(5) eV per atom."
    },
    {
        "anchor": "Large Thermopower in a Layered Oxide NaCo_2O_4: A transition-metal oxide NaCo_2O_4 is a layered oxide in which CoO_2 and Na\nalternately stack along the c axis. Recently we have found that this compound\nshows unusually large thermopower with low resistivity, which is comparable to\nthose of Bi_2Te_3. The negative transverse magnetoresistance and the strongly\ntemperature-dependent Hall coefficient suggest that electron correlation\ndominates the conduction mechanism in NaCo_2O_4.",
        "positive": "Single-particle states in spherical Si/SiO$_2$ quantum dots: We calculate ground and excited electron and hole levels in spherical Si\nquantum dots inside SiO$_2$ in a multiband effective mass approximation.\nLuttinger Hamiltonian is used for holes and the strong anisotropy of the\nconduction electron effective mass in Si is taken into account. As boundary\nconditions for electron and hole wave functions we use continuity of the wave\nfunctions and the velocity density at the boundary of the quantum dots."
    },
    {
        "anchor": "Assessment of the Thermal Conductivity of BN-C Nanostructures: Chemical and structural diversity present in hexagonal boron nitride ((h-BN)\nand graphene hybrid nanostructures provide new avenues for tuning various\nproperties for their technological applications. In this paper we investigate\nthe variation of thermal conductivity ($\\kappa$) of hybrid graphene/h-BN\nnanostructures: stripe superlattices and BN (graphene) dots embedded in\ngraphene (BN) are investigated using equilibrium molecular dynamics. To\nsimulate these systems, we have parameterized a Tersoff type interaction\npotential to reproduce the ab initio energetics of the B-C and N-C bonds for\nstudying the various interfaces that emerge in these hybrid nanostructures. We\ndemonstrate that both the details of the interface, including energetic\nstability and shape, as well as the spacing of the interfaces in the material\nexert strong control on the thermal conductivity of these systems. For stripe\nsuperlattices, we find that zigzag configured interfaces produce a higher\n$\\kappa$ in the direction parallel to the interface than the armchair\nconfiguration, while the perpendicular conductivity is less prone to the\ndetails of the interface and is limited by the $\\kappa$ of h-BN. Additionally,\nthe embedded dot structures, having mixed zigzag and armchair interfaces,\naffects the thermal transport properties more strongly than superlattices.\nThough dot radius appears to have little effect on the magnitude of reduction,\nwe find that dot concentration (50% yielding the greatest reduction) and\ncomposition (embedded graphene dots showing larger reduction that h-BN dot)\nhave a significant effect.",
        "positive": "Magnetic and Transport Properties of NiFe/SiO_{2}/NiFe Trilayers: Magnetic coupling between Ni_{81}Fe_{19} double thin films separated by an\ninsulating SiO_{2} spacer layer is investigated with structural measurements,\ncross sectional imaging, magnetization measurements (BH loop) and transport\nunder the conditions of variable spacer thickness ranging from 0 to 5000\nAngstroms. We investigate several models to explain the coercivity variation\nwith spacer thickness as well as the transport measurements."
    },
    {
        "anchor": "Enabling accurate first-principle calculations of electronic properties\n  with a corrected k.p scheme: A computationally inexpensive k.p-based interpolation scheme is developed\nthat can extend the eigenvalues and momentum matrix elements of a sparsely\nsampled k-point grid into a densely sampled one. Dense sampling, often required\nto accurately describe transport and optical properties of bulk materials, can\nbe demanding to compute, for instance, in combination with hybrid functionals\nin density functional theory (DFT) or with perturbative expansions beyond DFT\nsuch as the $GW$ method. The scheme is based on solving the k.p method and\nextrapolating from multiple reference k-points. It includes a correction term\nthat reduces the number of empty bands needed and ameliorates band\ndiscontinuities. We show how the scheme can be used to generate accurate band\nstructures, density of states, and dielectric functions. Several examples are\ngiven, using traditional and hybrid functionals, with Si, TiNiSn, and Cu as\nmodel materials. We illustrate that d-electron and semi-core states, which are\nparticular challenging for the k.p method, can be handled with the correction\nscheme if the sparse grid is not too sparse.",
        "positive": "Transformation kinetics of alloys under non-isothermal conditions: The overall solid-to-solid phase transformation kinetics under non-isothermal\nconditions has been modeled by means of a differential equation method. The\nmethod requires provisions for expressions of the fraction of the transformed\nphase in equilibrium condition and the relaxation time for transition as\nfunctions of temperature. The thermal history is an input to the model. We have\nused the method to calculate the time/temperature variation of the volume\nfraction of the favored phase in the alpha-to-beta transition in a zirconium\nalloy under heating and cooling, in agreement with experimental results. We\nalso present a formulation that accounts for both additive and non-additive\nphase transformation processes. Moreover, a method based on the concept of path\nintegral, which considers all the possible paths in thermal histories to reach\nthe final state, is suggested."
    },
    {
        "anchor": "Critical field anisotropy in the antiferroelectric switching of PbZrO3\n  films: Antiferroelectrics have been recently sparking interest due to their\npotential use in energy storage and electrocaloric cooling. Their main\ndistinctive feature is antiferroelectric switching, i.e. the possibility to\ninduce a phase transition to a polar phase by an electric field. Here we\ninvestigate the switching behavior of the model antiferroelectric perovskite\nPbZrO3 using thin films processed by chemical solution deposition in different\ngeometries and orientations. Both out-of-plane and in-plane switching\nconfigurations are investigated. The critical field is observed to be highly\ndependent on the direction of the electric field with respect to the film\ntexture. We show that this behaviour is qualitatively consistent with a phase\ntransition to a rhombohedral polar phase. We finally estimate the importance of\ncrystallite orientation and film texturation in the variations observed in the\nliterature.",
        "positive": "Physical properties of spinel-type superconductors CuRh2S4 and CuRh2Se4:\n  A DFT study: The structural, elastic, electronic, Vickers-Hardness, vibrational, Optical\nand thermodynamical properties of potentially technologically significant\nsuperconductors CuRh2S4 and CuRh2Se4 have calculated using density functional\ntheory (DFT) with CASTEP code.The calculated lattice parameters and other\nproperties have compared with available experimental values and found good\nagreement with them.The valence band and conduction bands overlapped each other\nat the Fermi level indicates the metallic conductivity of CuRh2S4 and CuRh2Se4.\nThe density of states shows that S-3p and Se-4p states are more effective at\nthe Fermi level.The charge density difference maps indicates the Cu-Rh bonds\nare stronger than Cu-S. The overall higher discussion notifies that the\nchemical bonding can be designated as an effective anisotropic connection\nbetween ionic, covalent and metallic interactions for CuRh2S4 and CuRh2Se4.The\nVickers-Hardness indicates the soft material with comparing to Diamond and\nsuitable to use wires and ribbon cables. The electron- and hole-like sheets\nmake the complex multisheet Fermi surface of CuRh2S4. The different optical\nfunctions are also observed clearly.The absorption spectra indicate that\nCuRh2S4 is more suitable to use in solar cell rather than CuRh2Se4. The\nreflectivity spectrum shows that these compounds have the potential to be used\na reflector material. Debye temperature indicates that CuRh2S4 and CuRh2Se4\nshould have advantages to use as a thermal barrier coating (TBC) material.The\nelectron-phonon coupling constant indicates the phonon-mediated medium coupled\nBCS superconductors. The obtained potential results in present calculation\ncould provide a significant movement for future studies."
    },
    {
        "anchor": "Mesoporous silica obtained with methyltriethoxysilane as co-precursor in\n  alkaline medium: Mesoporous silica particles have been synthesized by sol-gel method from\ntetraethoxysilane (tetraethylorthosilicate, TEOS) and methyltriethoxysilane\n(MTES), in ethanol and water mixture, at different ratios of the of the silica\nprecursors. Ammonia was used as catalyst at room temperature and\nhexadecyltrimethylammonium bromide (cetyltrimethylammonium bromide, CTAB) as\nthe structure directing agent. Nitrogen sorption, X-ray diffraction and\nsmall-angle neutron scattering gave information on the evolution of the gel\nstructure and pore morphologies in the function of MTES/TEOS molar ratio.\nThermogravimetric and differential thermal analysis showed that with addition\nof MTES the exothermic peak indicating the oxidation of the low molecular\nweight organic fragments shift to higher temperature. A room-temperature,\none-pot synthesis of MCM-41 type materials is presented, in which the variation\nof the MTES concentration allows to change the hydrophobicity, preserving the\nspecific properties materials, like the ordered pore structure, large specific\nsurface area and high porosity, making them suitable for selective uptake of\nguest species in drug loading applications. Specifically, the obtained\nmaterials had cylindrical pores, specific surface areas up to 1101 m2/g and\ntotal pore volumes up to 0.473 cm3/g. The obtained mesoporous materials are\nsusceptible for further functionalization to improve their selective uptake of\nguest species in drug delivery applications.",
        "positive": "Surface diffusion coefficients by thermodynamic integration: Cu on\n  Cu(100): The rate of diffusion of a Cu adatom on the Cu(100) surface is calculated\nusing thermodynamic integration within the transition state theory. The results\nare found to be in excellent agreement with the essentially exact values from\nmolecular-dynamics simulations. The activation energy and related entropy are\nshown to be effectively independent of temperature, thus establishing the\nvalidity of the Arrhenius law over a wide range of temperatures. Our study\ndemonstrates the equivalence of diffusion rates calculated using thermodynamic\nintegration within the transition state theory and direct molecular-dynamics\nsimulations."
    },
    {
        "anchor": "High-pressure polymeric nitrogen allotrope with the black phosphorus\n  structure: Studies of polynitrogen phases are of great interest for fundamental science\nand for the design of novel high energy density materials. Laser heating of\npure nitrogen at 140 GPa in a diamond anvil cell led to the synthesis of a\npolymeric nitrogen allotrope with the black phosphorus structure, bp-N. The\nstructure was identified in situ using synchrotron single-crystal X-ray\ndiffraction and further studied by Raman spectroscopy and density functional\ntheory calculations. The discovery of bp-N brings nitrogen in line with heavier\npnictogen elements, resolves incongruities regarding polymeric nitrogen phases\nand provides insights into polynitrogen arrangements at extreme densities.",
        "positive": "Tuning of crystal structure and magnetic properties by exceptionally\n  large epitaxial strains: Huge deformations of the crystal lattice can be achieved in materials with\ninherent structural instability by epitaxial straining. By coherent growth on\nseven different substrates the in-plane lattice constants of 50 nm thick\nFe70Pd30 films are continuously varied. The maximum epitaxial strain reaches\n8,3 % relative to the fcc lattice. The in-plane lattice strain results in a\nremarkable tetragonal distortion ranging from c/abct = 1.09 to 1.39, covering\nmost of the Bain transformation path from fcc to bcc crystal structure. This\nhas dramatic consequences for the magnetic key properties. Magnetometry and\nX-ray circular dichroism (XMCD) measurements show that Curie temperature,\norbital magnetic moment, and magnetocrystalline anisotropy are tuned over broad\nranges."
    },
    {
        "anchor": "Ab initio optical and energy loss spectra of transition metal\n  monopnictides TaAs, TaP, NbAs, and NbP: Transition metal monopnictides represent a new class of topological\nsemimetals with low-energy excitations, namely, Weyl fermions. We report\noptical properties across a wide spectral energy range for TaAs, TaP, NbAs and\nNbP, calculated within density functional theory. Spectra are found to be\nsomewhat independent of the anion and the light polarization. Their features\nare explained in terms of the upper $s$, $p$, $d$, and $f$ electrons.\nCharacteristic absorption features are related to the frequency dependence of\nthe Fresnel reflectivity. While the lower part of the energy loss spectra is\ndominated by plasmonic features, the high-energy structures are explained by\ninterband transitions.",
        "positive": "Automated construction of symmetrized Wannier-like tight-binding models\n  from ab initio calculations: Wannier tight-binding models are effective models constructed from\nfirst-principles calculations. As such, they bridge a gap between the accuracy\nof first-principles calculations and the computational simplicity of effective\nmodels. In this work, we extend the existing methodology of creating Wannier\ntight-binding models from first-principles calculations by introducing the\nsymmetrization post-processing step, which enables the production of\nWannier-like models that respect the symmetries of the considered crystal.\nFurthermore, we implement automatic workflows, which allow for producing a\nlarge number of tight-binding models for large classes of chemically and\nstructurally similar compounds, or materials subject to external influence such\nas strain. As a particular illustration, these workflows are applied to\nstrained III-V semiconductor materials. These results can be used for further\nstudy of topological phase transitions in III-V quantum wells."
    },
    {
        "anchor": "Transport and Magnetic Properties of FexVse2 (x = 0 - 0.33): We present our results of the effect of Fe intercalation on the structural,\ntransport and magnetic properties of 1T-VSe2. Intercalation of iron, suppresses\nthe 110K charge density wave (CDW) transition of the 1T-VSe2. For the higher\nconcentration of iron, formation of a new kind of first order transition at\n160K takes place, which go on stronger for the 33% Fe intercalation.\nThermopower of the FexVSe2 compounds (x = 0 - 0.33), however do not show any\nanomaly around the transition. The intercalation of Fe does not trigger any\nmagnetism in the weak paramagnetic 1T-VSe2, and Fe is the low spin state of\nFe3+.",
        "positive": "A spin-wave frequency doubler by domain wall oscillation: We present a new mechanism for spin-wave excitation using a pinned domain\nwall which is forced to oscillate at its eigenfrequency and radiates spin\nwaves. The domain wall acts as a frequency doubler, as the excited spin waves\nhave twice the frequency of the domain wall oscillation. The investigations\nhave been carried out using micromagnetic simulations and enable the\ndetermination of the main characteristics of the excited spin-waves such as\nfrequency, wavelength, and velocity. This behavior is understood by the\noscillation in the perpendicular magnetization which shows two anti-nodes\noscillating out of phase with respect to each other."
    },
    {
        "anchor": "Selective Hydrogenation Promotes Anisotropic Thermoelectric Properties\n  of TPDH-Graphene: We have combined DFT calculations with the Boltzmann semiclassical transport\ntheory to investigate the effect of selective hydrogenation on the\nthermoelectric properties of tetra-penta-deca-hexagonal graphene (TPDH-gr), a\nrecently proposed new 2D carbon allotrope. Our results show that the Seebeck\ncoefficient is enhanced after hydrogenation. The conductivity along the x\ndirection is increased almost eight times while being almost suppressed along\nthe y direction. This behavior can be understood in terms of the electronic\nstructure changes due to the appearance of a Dirac-like cone after the\nselective hydrogenation. Consistent with the literature, the electronic\ncontribution to thermal conductivity displays the same qualitative behavior as\nthe conductivity, as expected from the Wiedemann-Franz law. The increase in\nthermal conductivity with temperature limits the material's power factor. The\nsignificant increase in the Seebeck coefficient and conductivity increases also\ncontribute to the thermal conductivity increase. These results show that\nhydrogenation is an effective method to improve the TPDH-gr thermoelectric\nproperties, and this carbon allotrope can be an effective material for\nthermoelectric applications.",
        "positive": "A new type-II lepidocrocite-type TiO2/GaSe heterostructure: Electronic\n  and optical properties, bandgap engineering, interaction with ultrafast laser\n  pulses: Recently, van der Waals heterostructure has attracted interest both\ntheoretically and experimentally for their potential applications in\nphotoelectronic devices, photovoltaic devices, plasmonic devices and\nphotocatalysis. Inspired by this, we design a lepidocrocite-type TiO2/GaSe\nheterostructure. Via first-principles simulations, we show that such a\nheterostructure is a direct bandgap semiconductor with a strong and broad\noptical absorption, ranging from visible light to UV region, exhibiting its\npotential application in photoelectronic and photovoltaic devices. With the\nplanar-averaged electron density difference and Bader charge analysis, the\nheterostructure shows a strong capacity of enhancing the charge redistribution\nespecially at the interface, prolonging the lifetime of excitons, and hence\nimproving photocatalytic performance. By applying biaxial strain and interlayer\ncoupling, the heterostructure exhibits a direct-indirect bandgap transition and\nshows a potential for mechanical sensors due to the smooth and linear variation\nof bandgaps. Furthermore, our result indicates that a lower interlayer distance\nleads to a stronger charge redistribution. The calculation of irradiating\nultrafast on the heterostructure further reveals a semiconductor-metal\ntransition for the heterostructure. Moreover, we find an enhanced induced\nplasmonic current in the heterostructure under both x-polarized and z-polarized\nlaser, which is beneficial to plasmonic devices designs. Our research provides\nvaluable insight in applying the lepidocrocite-type TiO2/GaSe heterostructure\nin photoelectronic, photovoltaic, photocatalytic, mechanical sensing and\nplasmonic realms."
    },
    {
        "anchor": "Color center fluorescence and spin manipulation in single crystal,\n  pyramidal diamond tips: We investigate bright fluorescence of nitrogen (NV)- and silicon-vacancy\ncolor centers in pyramidal, single crystal diamond tips which are commercially\navailable as atomic force microscope probes. We coherently manipulate NV\nelectronic spin ensembles with $T_2 = 7.7(3)\\,\\mu$s. Color center lifetimes in\ndifferent tip heights indicate effective refractive index effects and\nquenching. Using numerical simulations, we verify enhanced photon rates from\nemitters close to the pyramid apex; a situation promising for scanning probe\nsensing.",
        "positive": "The Hall effect and hole densities in high Tc GaMnAs thin films: By studying the Hall effect in a series of low resistivity Ga1-xMnxAs\nsamples, accurate values for the hole density p, Mn concentration x, and Curie\ntemperature Tc are obtained over the range 0.015=<x=<0.08. The hole density\ncorresponds to 90% of the Mn concentration at low x, and has a maximum value of\n1.0x10-27 m-3 when Tc=125K for x=0.06. This data allows the first meaningful\ncomparison of mean field predicted Curie temperatures with experiment over a\nwide range of x. The theory is in qualitative agreement with experiment, but\noverestimates Tc at large x and underestimates TC at low x."
    },
    {
        "anchor": "A story of high-temperature ferromagnetism in semiconductors: The comprehensive search for multifunctional materials has resulted in the\ndiscovery of semiconductors and oxides showing ferromagnetic features\npersisting to room temperature. In this tutorial review the methods of\nsynthesis of these materials, as well as the application of element-specific\nnano-analytic tools, particularly involving synchrotron radiation and electron\nmicroscopy, are described and shown to reveal the presence of nano-scale phase\nseparations. Various means to control the aggregation of magnetic cations are\ndiscussed together with the mechanisms accounting for ferromagnetism of either\ncondensed or diluted magnetic semiconductors. Finally, the question of whether\nhigh temperature ferromagnetism is possible in semiconductors not containing\nmagnetic ions is touched upon.",
        "positive": "Hidden spin-texture at topological domain walls drive exchange bias in a\n  Weyl semimetal: Exchange bias is a phenomenon critical to solid-state technologies that\nrequire spin valves or non-volatile magnetic memory. The phenomenon is usually\nstudied in the context of magnetic interfaces between antiferromagnets and\nferromagnets, where the exchange field of the former acts as a means to pin the\npolarization of the latter. In the present study, we report an unusual instance\nof this phenomenon in the topological Weyl semimetal Co3Sn2S2, where the\nmagnetic interfaces associated with domain walls suffice to bias the entire\nferromagnetic bulk. Remarkably, our data suggests the presence of a hidden\norder parameter whose behavior can be independently tuned by applied magnetic\nfields. For micron-size samples, the domain walls are absent, and the exchange\nbias vanishes, suggesting the boundaries are a source of pinned uncompensated\nmoment arising from the hidden order. The novelty of this mechanism suggests\nexciting opportunities lie ahead for the application of topological materials\nin spintronic technologies."
    },
    {
        "anchor": "Green Fabrication of Lanthanide doped Hydroxide-based Phosphors:\n  Y(OH)3:Eu3+ Nanoparticles for White Light Generation: Phosphors serve as color conversion layers to generate white light with\nvarying optical features including CRI, CCT, and luminous efficacy. However,\nthey have been produced in harsh synthesis conditions such as high temperature,\nhigh pressure, and/or employing a huge amount of solvents. In this work,\nfacile, water-based and a rapid method has been proposed to fabricate\nlanthanide doped hydroxide-based phosphors. In this sense, submicrometer-sized\nY(OH)3:Eu3+ particles, as red phosphor, were synthesized in water at ambient\nconditions in <60 min reaction time. The doping ratio is controlled from 2.5 to\n20% in terms of mole. Meanwhile, first principle calculations were also\nperformed on Y(OH)3:Eu3+ to understand the preferable doping scenario and its\noptoelectronic properties. As an application, these fabricated red phosphors\nwere integrated into PDMS/YAG:Ce3+ composite to generate white light. The\nresulting white light showed a remarkable improvement (~24%) for LER, a slight\nreduction of CCT (from 3900K to 3600K), and an unchanged CRI (~60) as the\namount of Y(OH)3:Eu3+ increases.",
        "positive": "Effects of point defects on oxidation of 3C-SiC: The influence of implantation-induced point defects (PDs) on SiC oxidation is\ninvestigated via molecular dynamics simulations. PDs generally increase the\noxidation rate of crystalline grains. Particularly, accelerations caused by Si\nantisites and vacancies are comparable, and followed by Si interstitials, which\nare higher than those by C antisites and C interstitials. However, in the grain\nboundary (GB) region, defect contribution to oxidation is more complex, with C\nantisites decelerating oxidation. The underlying reason is the formation of a\nC-rich region along the oxygen diffusion pathway that blocks the access of O to\nSi and thus reduces the oxidation rate, as compared to the oxidation along a GB\nwithout defects."
    },
    {
        "anchor": "Near dispersion-less surface plasmon polariton resonances at a\n  metal-dielectric interface: Omni-directional light coupling to surface plasmon polariton (SPP) modes to\nmake use of plasmon mediated near-field enhancement is challenging. We report\npossibility of near dispersion-less modes in structures with unpatterned\nmetal-dielectric interfaces having 2-D dielectric patterns on top. We show that\nthe position and dispersion of the excited modes can be controlled by the\nexcitation geometry and the 2-D pattern. The anti-crossings resulting from the\nin-plane coupling of different SPP modes are also shown.",
        "positive": "The Electron-Phonon Coupling Constant for Single-Layer Graphene on Metal\n  Substrates Determined from He Atom Scattering: Recent theory has demonstrated that the value of the electron-phonon coupling\nstrength $\\lambda$ can be extracted directly from the thermal attenuation\n(Debye-Waller factor) of Helium atom scattering reflectivity. This theory is\nhere extended to multivalley semimetal systems and applied to the case of\ngraphene on different metal substrates and graphite. It is shown that $\\lambda$\nrapidly increases for decreasing graphene-substrate binding strength. Two\ndifferent calculational models are considered which produce qualitatively\nsimilar results for the dependence of $\\lambda$ on binding strength. These\nmodels predict, respectively, values of $\\lambda_{HAS} = 0.89$ and 0.32 for a\nhypothetical flat free-standing single-layer graphene with cyclic boundary\nconditions. The method is suitable for analysis and characterization of not\nonly the graphene overlayers considered here, but also other layered systems\nsuch as twisted graphene bilayers."
    },
    {
        "anchor": "Calculation of thermal expansion coefficient of Fe/sub 3/Al with the\n  addition of transition metal elements: The addition of transition metal elements can significantly modify physical\nproperties of intermetalic compounds. We studied the influence of Molybdenum\nand Vanadium additives on thermal expansion coefficient (CTE) of Fe/sub 3/Al\nand FeAl over the wide range of temperatures. The site preference of both\ntransition metals was determined by full-potential LMTO method within the\ngrandcanonical formalism. At low temperatures CTEs were found directly from the\nFP-LMTO calculations by incorporating them into the Debye model of a solid. The\nobtained thermal expansion for pure Fe/sub 3/Al and FeAl is within 10% of its\nexperimentally measured values. At high temperatures we performed molecular\ndynamics simulations based on our many-body atomistic potentials. The\nparameters were fitted to reproduce the total energy of a crystal under various\ntypes of deformations obtained by FP-LMTO method and were tested with respect\nto different structures and vacancy formation energies. Our calculations show\nthat addition of V decreases the CTEs of both iron-aluminides, while the\naddition of Mo makes Fe/sub 3/Al DO3 structure unstable.",
        "positive": "Hydrogen transport within graphene multilayers by means of flexural\n  phonons: Graphene sustains transverse out-of-plane mechanical vibrations (flexural\nphonons). At the nanometer scale, these appear as travelling ripples, or\ncavities, if excited in counter-phase in alternate multilayers. In this work we\nexplore by means of classical molecular dynamics simulations the possibility of\nusing these moving nano-cavities to actively transport hydrogen. We find that\nthe gas can be efficiently transported for hundreds of nanometers in the wave\npropagation direction, before the phonons damp down. Therefore, this effect\ncould be used to move and pump gases through multilayers graphene based\nframeworks."
    },
    {
        "anchor": "Chemical functionalization of graphene: Experimental and theoretical results on chemical functionalization of\ngraphene are reviewed. Using hydrogenated graphene as a model system, general\nprinciples of the chemical functionalization are formulated and discussed. It\nis shown that, as a rule, 100% coverage of graphene by complex functional\ngroups (in contrast with hydrogen and fluorine) is unreachable. A possible\ndestruction of graphene nanoribbons by fluorine is considered. The\nfunctionalization of infinite graphene and graphene nanoribbons by oxygen and\nby hydrofluoric acid is simulated step by step.",
        "positive": "Magnetic Coupling in Ferromagnetic Semiconductor GaMnAs/AlGaMnAs Bilayer\n  Devices: We carefully investigated the ferromagnetic coupling in the as-grown and\nannealed ferromagnetic semiconductor GaMnAs/AlGaMnAs bilayer devices. We\nobserved that the magnetic interaction between the two layers strongly affects\nthe magnetoresistance of the GaMnAs layer with applying out of plane magnetic\nfield. After low temperature annealing, the magnetic easy axis of the AlGaMnAs\nlayer switches from out of plane into in-plane and the interlayer coupling\nefficiency is reduced from up to 0.6 to less than 0.4. However, the magnetic\ncoupling penetration depth for the annealed device is twice that of the\nas-grown bilayer device."
    },
    {
        "anchor": "Effect of Co and Fe on the inverse magnetocaloric properties of Ni-Mn-Sn: At certain compositions Ni-Mn-$X$ Heusler alloys ($X$: group IIIA-VA\nelements) undergo martensitic transformations, and many of them exhibit inverse\nmagnetocaloric effects. In alloys where $X$ is Sn, the isothermal entropy\nchange is largest among the Heusler alloys, particularly in\nNi$_{50}$Mn$_{37}$Sn$_{13}$ where it reaches a value of 20 Jkg$^{-1}$K$^{-1}$\nfor a field of 5T. We substitute Ni with Fe and Co in this alloy, each in\namounts of 1 at% and 3 at% to perturb the electronic concentration and examine\nthe resulting changes in the magnetocaloric properties. Increasing both Fe and\nCo concentrations causes the martensitic transition temperature to decrease,\nwhereby the substitution by Co at both compositions or substituting 1 at% Fe\nleads to a decrease in the magnetocaloric effect. On the other hand, the\nmagnetocaloric effect in the alloy with 3 at% Fe leads to an increase in the\nvalue of the entropy change to about 30 Jkg$^{-1}$K$^{-1}$ at 5T.",
        "positive": "Controlling exchange coupling strength in NixCu100-x thin films: Thickness (dF) and concentration (x) dependence of the Curie temperature of\nNixCu100-x(dF) ferromagnetic alloy layers (x =0.55,0.65, dF =[3nm{\\div}12nm])\nbeing in contact with a vanadium layer was studied. The Curie temperature of\nthe ferromagnetic layers depends on the thickness when it is comparable with\nthe interface layer between the F and the vanadium layers, which is attributed\nto the proximity coupling of the interface region with the rest of the F layer.\nThe present study provides valuable information for fabrication of samples with\ncontrolled exchange coupling strength for studies of superconductor/ferromagnet\n(S/F) proximity effects."
    },
    {
        "anchor": "N-doped graphitic carbon materials hybridized with transition metals\n  (compounds) for hydrogen evolution reaction: Understanding the synergistic\n  effect from atomistic level: The hybrid nanostructures of nitrogen doped carbon materials and nonprecious\ntransition metals are among the most promising electrocatalysts to replace\nnoble metal catalysts for renewable energy applications. However, the\nfundamental principles governing the catalytic activity of such hybrid\nmaterials remain elusive. Herein, we systematically explore the\nelectrocatalytic properties of transition metals, transition metal oxides and\ncarbides substrates covered by nitrogen-doped graphitic sheets for hydrogen\nevolution reaction (HER). Our first-principles calculations show that the\ngraphitic sheet is prominently activated by the nitrogen doping and the\ncoordinate bond with metal (compound) substrate through intralayer and\ninterlayer charge transfer. Such hybrid materials can provide optimal binding\ncapability for HER catalysis with Tafel barrier down to 1.0 eV. The HER\nactivity can be correlated to the C pz band center, which is in turn governed\nby the electronic coupling strength between the graphitic sheet and metal\nsubstrate, thus paving a way to rational design of graphitic carbon/transition\nmetal hybrid electrocatalysts of high performance.",
        "positive": "Topological Phase Transition in Single Crystals of $(Cd_{1-x} Zn_x)_3\n  As_2$: Single crystals of $(Cd_{1-x} Zn_x)_3 As_2$ were synthesized from\nhigh-temperature solutions and characterized in terms of their structural and\nelectrical properties. Based on the measurements of resistivity and Hall\nsignals, we revealed a chemical-doping-controlled transition from a three\ndimensional Dirac semimetal to a semiconductor with a critical point $x_c/sim\n0.38$. We observed structural transitions from a body-center tetragonal phase\nto a primary tetragonal phase then back to a body-center tetragonal phase in\nthe solid solutions as well, which are irrelevant to the topological phase\ntransition. This continuously tunable system controlled by chemical doping\nprovides a platform for investigating the topological quantum phase transition\nof 3D Dirac electrons."
    },
    {
        "anchor": "Micro-Structuring, Ablation and Defect Generation in Graphene with\n  Femtosecond Pulses: Femtosecond micromachining offers a contact-free and mask-less technique for\nmaterial patterning. With ultrafast laser irradiation, permanent modifications\nto the properties of single layer graphene through material ablation or defect\nintroduction can be induced. Multiple femtosecond pulse interactions with a\nsingle layer graphene are studied and a low laser ablation threshold ~9.2\nmJ/cm2 is reported for a 15 second illumination time. Clean ablated structures\nare generated in such a multi pulse irradiation configuration at low pulse\nenergies as an attractive alternative to ablation with single femtosecond, high\nenergy pulses. For a fully ablated graphene hole, a radially symmetric region\nextending around 2 um from the ablated edge is characterized by strong defect\ngeneration. Average distances between point-defects down to ~58 nm are derived\nand Raman spectroscopy implies that overall there is a strong resemblance to\namorphous structures. For fluence values around 75% of the ablation threshold,\nmodification with defect generation down to ~48 nm average defects lengths is\nreported, while the underlying graphene structure is maintained. Thus,\ndepending on the laser parameter choice, the same laser configuration can be\nused to ablate graphene or to primarily introduce defect states. The presented\nfindings offer interesting insights into femtosecond induced structural\nmodifications of graphene that can lead to improved precision ablation and\npatterning of single-layer materials at the micro- and nano-scale. Further,\nthis can be attractive for graphene or carbon-based device fabrication as well\nas sensor and transistor applications, where regions of varying carrier\nconcentrations and different electrical, optical or physical properties are\ndesired.",
        "positive": "Coexistence of phases and interphase boundaries in BaTiO3: A theoretical analysis of the internal structure of interphase boundaries\nseparating domains of coexisting phases are presented for the perovskite\nferroelectric BaTiO3. The temperature dependence of interphase boundary widths\nand surface energies are calculated and compared with the corresponding\nparameters for different types of domain walls existing within the\nferroelectric phases of BaTiO3."
    },
    {
        "anchor": "Charge migration in organic materials: Can propagating charges affect\n  the key physical quantities controlling their motion?: Charge migration is a ubiquitous phenomenon with profound implications\nthroughout many areas of chemistry, physics, biology and materials science. The\nlong-term vision of designing functional materials with tailored molecular\nscale properties has triggered an increasing quest to identify prototypical\nsystems where truly molecular conduction pathways play a fundamental role. Such\npathways can be formed due to the molecular organization of various organic\nmaterials and are widely used to discuss electronic properties at the nanometer\nscale. Here, we present a computational methodology to study charge propagation\nin organic molecular stacks at nano and sub-nanoscales and exploit this\nmethodology to demonstrate that moving charge carriers strongly affect the\nvalues of the physical quantities controlling their motion. The approach is\nalso expected to find broad application in the field of charge migration in\nsoft matter systems.",
        "positive": "Direct formation of nitrogen-vacancy centers in nitrogen doped diamond\n  along the trajectories of swift heavy ions: We report depth-resolved photoluminescence measurements of nitrogen-vacancy\n(NV$^-$) centers formed along the tracks of swift heavy ions (SHIs) in type Ib\nsynthetic single crystal diamonds that had been doped with 100 ppm nitrogen\nduring crystal growth. Analysis of the spectra shows that NV$^-$ centers are\nformed preferentially within regions where electronic stopping processes\ndominate and not at the end of the ion range where elastic collisions lead to\nformation of vacancies and defects. Thermal annealing further increases NV\nyields after irradiation with SHIs preferentially in regions with high vacancy\ndensities. NV centers formed along the tracks of single swift heavy ions can be\nisolated with lift-out techniques for explorations of color center qubits in\nquasi-1D registers with an average qubit spacing of a few nanometers and of\norder 100 color centers per micrometer along 10 to 30 micrometer long\npercolation chains."
    },
    {
        "anchor": "Interweaving Polar Charge Orders in a Layered Metallic Super-atomic\n  Crystal: Electronic properties of super-atomic crystals have not been sufficiently\nexplored due to the versatility of their building units; moreover, their\ninter-unit couplings are even poorly understood. Here, we present a joint\nexperiment-theory investigation of a rational-designed layered super-atomic\ncrystal of Au6Te12Se8 cubes, stacked by non-covalent inter-cube quasi-bonds. We\nfound a sequential-emerged anisotropic triple-cube charge-density-wave (tc-CDW)\nand polarized metallic states below 120 K, as revealed via scanning tunneling\nmicroscopy/spectroscopy, angle-resolved photoemission spectroscopy, transport\nmeasurement, Raman spectra, and density functional theory. The polarized states\nare locked in an anti-parallel configuration, which is required for maintaining\nthe inversion symmetry of the center-cube in the tc-CDW. The anti-polar\nmetallic states are thus interweaved by the charge-density-wave and the\npolarized metallic states, and primarily ascribed to electronic effects via\ntheoretical calculations. This work not only demonstrates a microscopic picture\nof the interweaved CDW and polarized charge orders in the super-atomic crystal\nof ATS, but also sheds light on expanding the existing category of quantum\nmaterials to non-covalent solids.",
        "positive": "Initial stage of the 2D-3D transition of a strained SiGe layer on a\n  pit-patterned Si(001) template: We investigate the initial stage of the 2D-3D transition of strained Ge\nlayers deposited on pit-patterned Si(001) templates. Within the pits, which\nassume the shape of inverted, truncated pyramids after optimized growth of a Si\nbuffer layer, the Ge wetting layer develops a complex morphology consisting\nexclusively of {105} and (001) facets. These results are attributed to a\nstrain-driven step-meandering instability on the facetted side-walls of the\npits, and a step-bunching instability at the sharp concave intersections of\nthese facets. Although both instabilities are strain-driven, their coexistence\nbecomes mainly possible by the geometrical restrictions in the pits. It is\nshown that the morphological transformation of the pit surface into low-energy\nfacets has strong influence on the preferential nucleation of Ge islands at the\nflat bottom of the pits."
    },
    {
        "anchor": "Electrical properties of III-Nitride LEDs: recombination-based injection\n  model and theoretical limits to electrical efficiency and electroluminescent\n  cooling: The current-voltage characteristic and ideality factor of III-Nitride quantum\nwell light-emitting diodes (LEDs) grown on bulk GaN substrates are\ninvestigated. At operating temperature, these electrical properties exhibit a\nsimple behavior. A model in which only active-region recombinations have a\ncontribution to the LED current is found to account for experimental results.\nThe limit of LED electrical efficiency is discussed based on the model and on\nthermodynamic arguments, and implications for electroluminescent cooling are\nexamined.",
        "positive": "Estimating Excitonic Effects in the Absorption Spectra of Solids:\n  Problems and Insight from a Guided Iteration Scheme: A major obstacle for computing optical spectra of solids is the lack of\nreliable approximations for capturing excitonic effects within time-dependent\ndensity-functional theory. We show that the trustful prediction of strongly\nbound electron-hole pairs within this framework using simple approximations is\nstill a challenge and that available promising results have to be revisited.\nDeriving a set of analytical formula we analyze and explain the difficulties.\nWe deduce an alternative approximation from an iterative scheme guided by\npreviously available knowledge, significantly improving the description of\nexciton binding energies. Finally, we show how one can \"read\" exciton binding\nenergies from spectra determined in the random phase approximation, without any\nfurther calculation."
    },
    {
        "anchor": "Material systems for FM-/AFM-coupled skyrmions in Co/Pt-based\n  multilayers: By means of systematic first-principles calculations based on density\nfunctional theory we search for suitable materials that can host\nantiferromagnetically coupled skyrmions. We concentrate on fcc-stacked\n(111)-oriented metallic $Z$/Co/Pt ($Z=4d$ series: Y$-$Pd, the noble metals: Cu,\nAg, Au, post noble metals: Zn and Cd) magnetic multilayers of films of\nmonatomic thickness. We present quantitative trends of magnetic properties:\nMagnetic moments, interlayer exchange coupling, spin-stiffness,\nDzyaloshinskii-Moriya interaction, magnetic anisotropy, and the critical\ntemperature. We show that some of the $Z$ elements (Zn, Y, Zr, Nb, Tc, Ru, Rh,\nand Cd) can induce antiferromagnetic interlayer coupling between the magnetic\nCo layers, and that they influence the easy magnetization axis. Employing a\nmultiscale approach, we transfer the micromagnetic parameters determined from\n$ab$ $initio$ to a micromagnetic energy functional and search for\none-dimensional spin-spiral solutions and two-dimensional skyrmions. We\ndetermine the skyrmion radius by numerically solving the equation of the\nskyrmion profile. We found an analytical expression for the skyrmion radius\nthat covers our numerical results and is valid for a large regime of\nmicromagnetic parameters. Based on this expression we have proposed a model\nthat allows to extrapolate from the $ab$ $initio$ results of monatomic films to\nmultilayers with Co films consisting of several atomic layers containing\n$10\\,$nm skyrmions. We found thickness regimes where tiny changes of the film\nthickness may alter the skyrmion radius by orders of magnitude. We estimated\nthe skyrmion size as function of temperature and found that the size can easily\ndouble going from cryogenic to room temperature. We suggest promising material\nsystems for ferromagnetically and antiferromagnetically coupled spin-spiral and\nskyrmion systems.",
        "positive": "Diamondoid Structure of Polymeric Nitrogen at High Pressures: High-pressure polymeric structures of nitrogen have attracted great attention\nowing to their potential application as high-energy-density materials. We\nreport the density functional structural prediction of the unexpected\nstabilization of a diamondoid (or N10-cage) structure of polymeric nitrogen at\nhigh pressures. The structure adopts a highly symmetric body-centered cubic\nform with lattice sites occupied by N10 tetracyclic cages, each of which\nconsists of 10 atoms and is covalently bonded with its six next-nearest N10\ncages. The prediction of this diamondoid structure rules out the earlier\nproposed helical tunnel phase and demonstrates the high-order nature of\npolymeric nitrogen at extreme high pressures. Diamondoid nitrogen is a wide-gap\ninsulator and energetically more favorable than the experimental cubic gauche\nand previously predicted layered Pba2 phases above 263 GPa, a pressure which is\naccessible to high pressure experiment."
    },
    {
        "anchor": "Defect-induced magnetism in SiC probed by nuclear magnetic resonance: We give evidence for intrinsic, defect-induced bulk paramagnetism in SiC by\nmeans of $^{13}$C and $^{29}$Si nuclear magnetic resonance (NMR) spectroscopy.\nThe temperature dependence of the internal dipole-field distribution, probed by\nthe spin part of the NMR Knight shift and the spectral linewidth, follows a\nCurie law and scales very well with the macroscopic DC susceptibility. In order\nto quantitatively analyze the NMR spectra, a microscopic model based on\ndipole-dipole interactions was developed. The very good agreement between these\nsimulations and the NMR data establishes a direct relation between the\nfrequency distribution of the spectral intensity and the corresponding\nreal-space volumes of nuclear spins. The presented approach by NMR can be\napplied to a variety of similar materials and, thus, opens a new avenue for the\nmicroscopic exploration and exploitation of diluted bulk magnetism in\nsemiconductors.",
        "positive": "Graphene on Ir(111) characterized by angle-resolved photoemission: Angle resolved photoelectron spectroscopy (ARPES) is extensively used to\ncharacterize the dependence of the electronic structure of graphene on Ir(111)\non the preparation process. ARPES findings reveal that temperature programmed\ngrowth alone or in combination with chemical vapor deposition leads to graphene\ndisplaying sharp electronic bands. The photoemission intensity of the Dirac\ncone is monitored as a function of the increasing graphene area. Electronic\nfeatures of the moir\\'e superstructure present in the system, namely minigaps\nand replica bands are examined and used as robust features to evaluate graphene\nuniformity. The overall dispersion of the pi-band is analyzed. Finally, by the\nvariation of photon energy, relative changes of the pi- and sigma-band\nintensities are demonstrated."
    },
    {
        "anchor": "Quantum Theory of Spontaneous Emission from Exciton-Electron-Phonon\n  Complex in Solid: Quantum Interference and Many-Body Effect: A full quantum mechanical theory for the spontaneous emission from excitons\nsimultaneously coupled to electronic excitations and anharmonic phonons in\nsolid is developed. Origin of detailed structures, such as zero-phonon line\nsplitting, Fano lineshape near one phonon sideband, strong second-order phonon\nStokes line, asymmetric phonon anti-Stokes lines, and two-electron satellites\nas well as their phonon replicas recently revealed in the low-temperature\nphotoluminescence of ZnO, has been identified by quantitative calculations from\nthe theory.",
        "positive": "First-Principles Study of Exchange Interactions of Yttrium Iron Garnet: Yttrium Iron Garnet is the ubiquitous magnetic insulator used for studying\npure spin currents. The exchange constants reported in the literature vary\nconsiderably between different experiments and fitting procedures. Here we\ncalculate them from first-principles. The local Coulomb correction (U - J) of\ndensity functional theory is chosen such that the parameterized spin model\nreproduces the experimental Curie temperature and a large electronic band gap,\nensuring an insulating phase. The magnon spectrum calculated with our\nparameters agrees reasonably well with that measured by neutron scattering. A\nresidual disagreement about the frequencies of optical modes indicates the\nlimits of the present methodology."
    },
    {
        "anchor": "Magnetic orders of LaTiO$_3$ under epitaxial strain: a first-principles\n  study: Perovskite LaTiO$_3$ bulk is a typical Mott-insulator with G-type\nantiferromagnetic order. In this work, the biaxial strain effects on the ground\nmagnetic order of LaTiO$_3$ films grown on various substrates have been\nstudied. For the compressive strain, LaTiO$_3$ films grown on LaAlO$_3$,\nLaGaO$_3$, and SrTiO$_3$ substrates undergo a phase transition from the\noriginal G-type antiferromagnet to A-type antiferromagnet. The underlying\nphysical mechanisms are the lattice distortions tunned by strain. While for the\ntensile strain, the BaTiO$_3$ and LaScO$_3$ substrates have been tested, which\nshow a tendency to transit the LaTiO$_3$ to the C-type antiferromagnet.\nFurthermore, our calculations find that the magnetic transitions under\nepitaxial strain do not change the insulating fact of LaTiO$_3$.",
        "positive": "Exploring leakage in dielectric films via automated experiment in\n  scanning probe microscopy: Electronic conduction pathways in dielectric thin films are explored using\nautomated experiments in scanning probe microscopy (SPM). Here, we use large\nfield of view scanning to identify the position of localized conductive spots\nand develop a SPM workflow to probe their dynamic behavior at higher spatial\nresolution as a function of time, voltage, and scanning process in an automated\nfashion. Using this approach, we observe the variable behaviors of the\nconductive spots in a 20 nm thick ferroelectric Hf0.54Zr0.48O2 film, where\nconductive spots disappear and reappear during continuous scanning. There are\nalso new conductive spots that appear during scanning. The automated workflow\nis universal and can be integrated into a wide range of microscopy techniques,\nincluding SPM, electron microscopy, optical microscopy, and chemical imaging."
    },
    {
        "anchor": "Elastic constants of stressed and unstressed materials in the phase\n  field crystal model: A general procedure to investigate the elastic response and calculate the\nelastic constants of stressed and unstressed materials through continuum field\nmodeling, particularly the phase field crystal (PFC) models, is presented. It\nis found that for a complete description of system response to elastic\ndeformation, the variations of all the quantities of lattice wave vectors,\ntheir density amplitudes (including the corresponding anisotropic variation and\ndegeneracy breaking), the average atomic density, and system volume should be\nincorporated. The quantitative and qualitative results of elastic constant\ncalculations highly depend on the physical interpretation of the density field\nused in the model, and also importantly, on the intrinsic pressure that usually\npre-exists in the model system. A formulation based on thermodynamics is\nconstructed to account for the effects caused by constant pre-existing stress\nduring the homogeneous elastic deformation, through the introducing of a\ngeneralized Gibbs free energy and an effective finite strain tensor used for\ndetermining the elastic constants. The elastic properties of both solid and\nliquid states can be well produced by this unified approach, as demonstrated by\nan analysis for the liquid state and numerical evaluations for the bcc solid\nphase. The numerical calculations of bcc elastic constants and Poisson's ratio\nthrough this method generate results that are consistent with experimental\nconditions, and better match the data of bcc Fe given by molecular dynamics\nsimulations as compared to previous work. The general theory developed here is\napplicable to the study of different types of stressed or unstressed material\nsystems under elastic deformation.",
        "positive": "Ultra-low power threshold for laser induced changes in optical\n  properties of 2D Molybdenum dichalcogenides: The optical response of traditional semiconductors depends on the laser\nexcitation power used in experiments. For two-dimensional (2D) semiconductors,\nlaser excitation effects are anticipated to be vastly different due to\ncomplexity added by their ultimate thinness, high surface to volume ratio, and\nlaser-membrane interaction effects. We show in this article that under laser\nexcitation the optical properties of 2D materials undergo irreversible changes.\nMost surprisingly these effects take place even at low steady state excitation,\nwhich is commonly thought to be non-intrusive. In low temperature\nphotoluminescence (PL) we show for monolayer (ML) MoSe2 samples grown by\ndifferent techniques that laser treatment increases significantly the trion\n(i.e. charged exciton) contribution to the emission compared to the neutral\nexciton emission. Comparison between samples exfoliated onto different\nsubstrates shows that laser induced doping is more efficient for ML MoSe2 on\nSiO2/Si compared to h-BN and gold. For ML MoS2 we show that exposure to laser\nradiation with an average power in the $\\mu$W/$\\mu$m$^2$ range does not just\nincrease the trion-to-exciton PL emission ratio, but may result in the\nirreversible disappearance of the neutral exciton PL emission and a shift of\nthe main PL peak to lower energy."
    },
    {
        "anchor": "A near real-time framework for extracting tip-sample forces in dynamic\n  atomic force microscopy (dAFM): The atomic force microscope (AFM) is a versatile, high-resolution tool used\nto characterize the topography and material properties of a large variety of\nspecimens at nano-scale. The interaction of the micro-cantilever tip with the\nspecimen causes cantilever deflections that are measured by an optical sensing\nmechanism and subsequently utilized to construct the sample topography. Recent\nyears have seen increased interest in using the AFM to characterize soft\nspecimens like gels and live cells. This remains challenging due to the complex\nand competing nature of tip-sample interaction forces - large tip-sample\ninteraction force is necessary to achieve good signal-to-noise ratios; However,\nlarge force tends to deform and destroy soft samples. In situ estimation of the\nlocal tip-sample interaction force is needed to control the AFM cantilever\nmotion and prevent destruction of soft samples while maintaining a good\nsignal-to-noise ratio. This necessitates the ability to rapidly estimate the\ntip-sample forces from the cantilever deflection during operation. This paper\nproposes a first approach to a near real-time framework for tip-sample force\ninversion. We pose the inverse problem of extracting the tip-sample force as an\nunconstrained optimization problem. A fast, parallel forward solver is\ndeveloped by utilizing graphical processing units (GPU). This forward solver\nshows an effective 30000 fold speed-up over a comparable CPU implementation,\nresulting in milli-second calculation times. The forward solver is coupled with\na GPU based particle-swarm optimization implementation. We illustrate the\nframework on three classes of tip-sample interaction inversions. Each of these\ninversions is performed in sub-second timings, showing potential for\nintegration with on-line AFM imaging and material characterization",
        "positive": "Line Broadening and Decoherence of Electron Spins in Phosphorus-Doped\n  Silicon Due to Environmental 29^Si Nuclear Spins: Phosphorus-doped silicon single crystals with 0.19 % <= f <= 99.2 %, where f\nis the concentration of 29^Si isotopes, are measured at 8 K using a pulsed\nelectron spin resonance technique, thereby the effect of environmental 29^Si\nnuclear spins on the donor electron spin is systematically studied. The\nlinewidth as a function of f shows a good agreement with theoretical analysis.\nWe also report the phase memory time T_M of the donor electron spin dependent\non both f and the crystal axis relative to the external magnetic field."
    },
    {
        "anchor": "High-mobility transport anisotropy and linear dichroism in few-layer\n  black phosphorus: Two-dimensional crystals are emerging materials for nanoelectronics.\nDevelopment of the field requires candidate systems with both a high carrier\nmobility and, in contrast to graphene, a sufficiently large electronic bandgap.\nHere we present a detailed theoretical investigation of the atomic and\nelectronic structure of few-layer black phosphorus (BP) in order to predict its\nelectrical and optical properties. This system has a direct bandgap, tunable\nfrom 1.51 eV for a monolayer to 0.59 eV for a 5-layer sample. We predict that\nthe mobilities are hole-dominated, rather high and highly anisotropic. The\nmonolayer is exceptional in having an extremely high hole-mobility (of order\n10000 cm$^{2}$ V$^{-1}$ s$^{-1}$) and anomalous elastic properties which\nreverse the anisotropy. Light absorption spectra indicate linear dichroism\nbetween perpendicular in-plane directions, which allows optical determination\nof the crystalline orientation and optical activation of the anisotropic\ntransport properties. These results make few-layer BP a promising candidate for\nfuture electronics.",
        "positive": "Acetonitrile on silica surfaces and at its liquid-vapor interface:\n  structural correlations and collective dynamics: Solvent structure and dynamics of acetonitrile at its liquid-vapor (LV)\ninterface and at the acetonitrile-silica (LS) interface are studied by means of\nmolecular dynamics simulations. We set up the interfacial system and treat the\nlong-ranged electrostatics carefully to obtain both stable LV and LS interfaces\nwithin the same system. Single molecule (singlet) and correlated density\norientational profiles and singlet and collective reorientational dynamics are\nreported for both interfaces. At the LS interface acetonitrile forms layers.\nThe closest sublayer is dominated by nitrogen atoms bonding to the hydrogen\nsites of the silica surface. The singlet molecular reorientation is strongly\nhindered when close to the silica surface, but at the LV interface it relaxes\nmuch faster than in the bulk. Antiparallel correlations between acetonitrile\nmolecules at the LV interface are even stronger than in the bulk liquid phase.\nThis strong antiparallel correlation disappears at the LS interface. The\ncollective reorientational relaxation of the first layer acetonitrile is much\nfaster than the singlet reorientational relaxation but it is still slower than\nin the bulk. These results are interpreted with reference to a variety of\nrecent experiments.\n  We found that defining interface properties based on the distribution of\npositions of different choices of atoms or sites within the molecule leads to\napparently different orientational profiles, especially at the LV interface. We\nprovide a general formulation showing that this ambiguity arises when the size\nof the molecule is comparable to the interfacial width and is particularly\nsignificant when there is a large difference in density at the upper and lower\nboundaries of the interface. We finally analyze the effect of electrostatics to\nshow the necessity of properly treating long-ranged electrostatics for\nsimulations of interfacial systems."
    },
    {
        "anchor": "A Review of Liquid Phase Epitaxial Grown Gallium Arsenide: Liquid phase epitaxy of gallium arsenide (LPE GaAs) has been investigated\nintensively from the late 1960's to the present and has now a special place in\nthe manufacture of wide band, compound semiconductor radiation detectors.\nAlthough this particular process appears to have gained prominence in the last\nthree decades, it is interesting to note that its origins reach back to 1836\nwhen Frankenheim made his first observations. A brief review is presented from\na semiconductor applications point of view on how this subject developed. This\nis followed by a report on LPE GaAs growth at the Australian Nuclear Science\nand Technology Organisation (ANSTO).",
        "positive": "Effects of high-power laser irradiation on sub-superficial graphitic\n  layers in single crystal diamond: We report on the structural modifications induced by a lambda = 532 nm\nns-pulsed high-power laser on sub-superficial graphitic layers in\nsingle-crystal diamond realized by means of MeV ion implantation. A systematic\ncharacterization of the structures obtained under different laser irradiation\nconditions (power density, number of pulses) and subsequent thermal annealing\nwas performed by different electron microscopy techniques. The main feature\nobserved after laser irradiation is the thickening of the pre-existing\ngraphitic layer. Cross sectional SEM imaging was performed to directly measure\nthe thickness of the modified layers, and subsequent selective etching of the\nburied layers was employed to both assess their graphitic nature and enhance\nthe SEM imaging contrast. In particular, it was found that for optimal\nirradiation parameters the laser processing induces a six-fold increase the\nthickness of sub superficial graphitic layers without inducing mechanical\nfailures in the surrounding crystal. TEM microscopy and EELS spectroscopy\nallowed a detailed analysis of the internal structure of the laser irradiated\nlayers, highlighting the presence of different nano graphitic and amorphous\nlayers. The obtained results demonstrate the effectiveness and versatility of\nhigh-power laser irradiation for an accurate tuning of the geometrical and\nstructural features of graphitic structures embedded in single crystal diamond,\nand open new opportunities in diamond fabrication."
    },
    {
        "anchor": "Prospects of Direct Growth Boron Nitride Films as Substrates for\n  Graphene Electronics: We present a route for direct growth of boron nitride via a polyborazylene to\nh-BN conversion process. This two-step growth process ultimately leads to a\n>25x reduction in the RMS surface roughness of h-BN films when compared to a\nhigh temperature growth on Al2O3(0001) and Si(111) substrates. Additionally,\nthe stoichiometry is shown to be highly dependent on the initial polyborazylene\ndeposition temperature. Importantly, CVD graphene transferred to direct-grown\nboron nitride films on Al2O3 at 400{\\deg}C results in a >1.5x and >2.5x\nimprovement in mobility compared to CVD graphene transferred to Al2O3 and SiO2\nsubstrates, respectively, which is attributed to the combined reduction of\nremote charged impurity scattering and surface roughness scattering. Simulation\nof mobility versus carrier concentration confirms the importance of limiting\nthe introduction of charged impurities in the h-BN film and highlights the\nimportance of these results in producing optimized h-BN substrates for high\nperformance graphene and TMD devices.",
        "positive": "Tunable hybridization of electronic states of graphene and a metal\n  surface: We present an approach to monitor and control the strength of the\nhybridization between electronic states of graphene and metal surfaces.\nInspecting the distribution of the $\\pi$ band in a high-quality graphene layer\nsynthesized on Ni(111) by angle-resolved photoemission, we observe a new \"kink\"\nfeature which indicates a strong hybridization between $\\pi$ and \\textit{d}\nstates of graphene and nickel, respectively. Upon deposition and gradual\nintercalation of potassium atoms into the graphene/Ni(111) interface, the\n\"kink\" feature becomes less pronounced pointing at potassium mediated\nattenuation of the interaction between the graphene and the substrate."
    },
    {
        "anchor": "Thermodynamic Origins of Structural Metastability in Two-Dimensional\n  Black Arsenic: Two-dimensional (2D) materials have aroused considerable research interests\nowing to their potential applications in nanoelectronics and optoelectronics.\nThermodynamic stability of 2D structures inevitably affects the performance and\npower consumption of the fabricated nanodevices. Black arsenic (b-As), as a\ncousin of black phosphorus, has presented the extremely high anisotropy in\nphysical properties. However, the systematic research on structural stability\nof b-As is still lack. Herein, we demonstrated the detailed analysis on\nstructural metastability of the natural b-As, and determined its existence\nconditions in terms of two essential thermodynamic variables as hydrostatic\npressure and temperature. Our results confirmed that b-As can only survive\nbelow 0.7 GPa, and then irreversibly transform to gray arsenic, in consistent\nwith our theoretical calculations. Furthermore, thermal annealing strategy was\ndeveloped to precisely control the thickness of b-As flake, and it sublimates\nat 300 oC. These results could pave the way for 2D b-As in many promising\napplications.",
        "positive": "Anti-Ferroelectric Thin Films Phase Diagrams: In the paper we consider size effects of phase transitions and polar\nproperties of the thin antiferroelectric films. We modified phenomenological\napproach proposed by Kittel. The Euler-Lagrange equations were solved by direct\nvariational method. The free energy with renormalized coefficients depending on\nthe film thickness has been derived. The approximate analytical expression for\nthe coefficients dependence on film thickness, temperature, polarization\ngradient coefficient and extrapolation lengths were obtained. We have shown how\nthe anti-ferroelectric double hysteresis loop transforms into the ferroelectric\nsingle one under the film thickness decrease. Proposed theoretical\nconsideration explains the experimental results obtained in antiferroelectric\nPbZrO_3 thin films."
    },
    {
        "anchor": "A first principles study on organic molecules encapsulated BN nanotubes: The electronic structures of boron nitride nanotubes (BNNTs) doped by organic\nmolecules are investigated with density functional theory. Electrophilic\nmolecule introduces acceptor states in the wide gap of BNNT close to the\nvalence band edge, which makes the doped system a $p$-type semiconductor.\nHowever, with typical nucleophilic organic molecules encapsulation, only deep\noccupied molecular states but no shallow donor states are observed. There is a\nsignificant electron transfer from BNNT to electrophilic molecule, while the\ncharge transfer between nucleophilic molecule and BNNT is neglectable. When\nboth electrophilic and nucleophilic molecules are encapsulated in the same\nBNNT, large charge transfer between the two kinds of molecules occurs. The\nresulted small energy gap can strongly modify the transport and optical\nproperties of the system.",
        "positive": "Demonstrating the potential of Accurate Absolute Cross-grain Stress and\n  Orientation correlation using Electron Backscatter Diffraction: We report a first exploration of High-angular-Resolution Electron Backscatter\nDiffraction, without using simulated Electron Backscatter Diffraction patterns\nas a reference, for absolute stress and orientation measurements in\npolycrystalline materials. By co-correlating the pattern center and fully\nexploiting crystal symmetry and plane-stress, simultaneous correlation of all\noverlapping regions of interest in multiple direct-electron-detector,\nenergy-filtered Electron Backscatter Diffraction patterns is achieved. The\npotential for highly accurate measurement of absolute stress, crystal\norientation and pattern center is demonstrated on a virtual polycrystalline\ncase-study, showing errors respectively below 20 MPa (or 1e-4 in strain), 7e-5\nrad and 0.06 pixels."
    },
    {
        "anchor": "In Situ characterization of the proton enhanced conductivity of 20nm\n  TiO2 thin-films obtained on the surface of optical fiber: We report in situ characterized TiO2 thin-films deposited on optical fiber,\nhaving thicknesses in the 20-100nm range, and having enhanced conductivity\nvalues of 700S/cm upon interacting with hydrogen. This conductivity was\nachieved in pure hydrogen at 800-900C, having a measured activation energy of\n0.26eV of the hopping type. Given the variability in the observed results, it\nis postulated that the highest conductivity achievable may be much greater than\nwhat is currently demonstrated. The conductivity is retained after cooling to\nambient temperatures as confirmed by Hall measurements, and subsequent\ngrazing-incidence x-ray diffraction and TEM measurements show the films to be\nin the rutile phase. The exceptional conductivity in these films is\nhypothesized to result from direct proton incorporation into the lattice\npopulating the conduction band with excess electrons, or from altering the\nTitania lattice to form conductive Magneli phases. The films did not display\nany evidence of transformations, however formation of Magneli phases was\nconfirmed for powders. These interesting results, observed by examining 20nm\nfilms on the surface of optical fiber in combination with the first impedance\nspectroscopy performed on films on optical fiber in high temperature Fuel Cell\ntype environments, confirm hypotheses arrived at in prior publications where\nthin-films of Titania had optical properties which could only be explained by\nthe current claim. Titania thin-films on optical-fiber are being explored for\nhigh temperature hydrogen derived energy generation, thermo-photonic energy\nconversion, and associated sensors due to their unique interactions with\nhydrogen.",
        "positive": "Zeeman splitting via spin-valley-layer coupling in bilayer MoTe2: Atomically thin transition metal dichalcogenides (TMDs) possess coupling of\nspin and valley degrees of freedom, making them promising for\nspin-valleytronics. ln monolayer TMDs, the emission helicity is locked to the\nvalleys as a consequence of spin-orbit coupling and inversion symmetry\nbreaking, leading to a valley analog of Zeeman effect in presence of\nout-of-plane magnetic field. As inversion symmetry is recovered in bilayers,\nthe emission helicity should no longer be locked to the valleys. Here we show\nthat Zeeman splitting, however, still persists in bilayers, as a result of an\nadditional degree of freedom viz., the layer pseudospin and spin-valley-layer\nlocking. In contrast to monolayer, Zeeman splitting here exists without lifting\nvalley degeneracy. The degree of circularly polarized photoluminescence can be\ntuned with magnetic field from $-27\\%$ to $27\\%$. Our results demonstrate the\ncontrol of degree of freedom in bilayer with magnetic field, which, together\nwith previous electric field control, makes bilayer a promising platform for\nspin-valley quantum gates based on magnetoelectric effects."
    },
    {
        "anchor": "Access to the full 3D Brillouin zone with time resolution, using a new\n  tool for pump-probe ARPES: Here we report the first time- and angle-resolved photoemission spectroscopy\n(TR-ARPES) with the new Fermiologics \"FeSuMa\" analyzer. The new experimental\nsetup has been commissioned at the Artemis laboratory of the UK Central Laser\nFacility. We explain here some of the advantages of the FeSuMa for TR-ARPES and\ndiscuss how its capabilities relate to those of hemispherical analyzers and\nmomentum microscopes. We have integrated the FeSuMa into an optimized\npump-probe beamline that permits photon-energy- (i.e., kz-) dependent scanning,\nusing probe energies generated from high harmonics in a gas jet. The advantages\nof using the FeSuMa in this situation include the possibility of taking\nadvantage of its \"fisheye\" mode of operation.",
        "positive": "Berry-phase theory of polar discontinuities at oxide-oxide interfaces: In the framework of the modern theory of polarization, we rigorously\nestablish the microscopic nature of the electric displacement field D. In\nparticular, we show that the longitudinal component of D is preserved at a\ncoherent and insulating interface. To motivate and elucidate our derivation, we\nuse the example of LAO/STO interfaces and superlattices, where the validity of\nthe above conservation law is not immediately obvious. Our results generalize\nthe \"locality principle\" of constrained-D density functional theory to the\nfirst-principles modeling of charge-mismatched systems."
    },
    {
        "anchor": "Vibrations of a one-dimensional host-guest system: A simple model shows how it is possible to create a gap in the vibrational\nspectrum of a one-dimensional lattice. The proposed model is a host-guest chain\nhaving, instead of point-like masses connected by spring, massive cages hosting\nparticles inside. We imagine the cage as a rigid box containing a mass linked\nby a spring to the box inner wall. The presence of guests creates an energy gap\nin the dispersion of vibrational frequencies. The gap is about the internal\nresonance of the mass hidden in the cage.",
        "positive": "Magnetization and magneto-transport studies on Fe$_2$VAl$_{1-x}$Si$_x$: We report on magnetoresistance, Hall and magnetization measurements of\nFe2VAl1-xSix Heusler compounds for x= 0.005, 0.015, 0.02. There is a systematic\nchange in the temperature coefficient of resistance (TCR) from negative to\npositive as the Si composition is increased. The Hall co-efficient shows that\nthe carriers are electron like and the carrier density increases with Si\nconcentration. Resistance measurements under magnetic field indicate a\ndecreasing behavior under the application of magnetic field at low temperature\nregion (T< 60 K), suggesting the suppression of scattering by magnetic field.\nTemperature and field dependent magnetization measurements did not show any\nsignificant change apart from the fact that the presence of super paramagnetic\n(SPM) cluster and its ordering at low temperatures. Arrott plot analysis of\nmagnetization versus field also indicates the magnetic ordering with applied\nfield below 60 K."
    },
    {
        "anchor": "Icosahedral quasicrystal-enhanced nucleation in Al alloys fabricated by\n  selective laser melting: Selective laser melting (SLM) is rapidly evolving to become a mainstream\ntechnology. However, the fundamental mechanisms of solidification and\nmicrostructure development inherent to the non-equilibrium conditions of this\nadditive manufacturing method, which differ largely from those typical of\nconventional processing techniques, remain widely unknown. In this work, an\nin-depth characterization of the microstructure of Al7075 SLM processed\nsamples, built from powder mixtures containing ZrH2 microparticles,\ndemonstrates the occurrence of icosahedral quasicrystal-enhanced nucleation\nduring laser fabrication. This solidification mechanism, only observed to date\nin cast Al-Zn and yellow gold alloys containing minute additions of Cr\n(Kurtuldu et al., 2013) or Ti (Chen et al. 2018), and Ir (Kurtuldu et al.,\n2014), is evidenced by the presence of an abnormally high fraction of twin\nboundaries and of five-fold orientation symmetry between twinned nearest\nneighbors lying within a matrix of equiaxed, randomly textured, ultrafine\ngrains. This research attests to the wide range of possibilities offered by\nadditive manufacturing methods for the investigation of novel physical\nmetallurgy phenomena as well as for the design of advanced metals.",
        "positive": "Synthesis of Nanoparticles of the Giant Dielectric Material, CaCu3Ti4O12\n  from a Precursor Route: A complex oxalate precursor, CaCu3(TiO)4(C2O4)8.9H2O, was synthesized and the\nprecipitate that obtained was confirmed to be monophasic by the wet chemical\nanalyses, X-ray diffraction, FTIR absorption and TG, DTA analyses. The thermal\ndecomposition of this oxalate precursor led to the formation of phase-pure\ncalcium copper titanate, CaCu3Ti4O12, at 680oC. The bright field TEM\nmicrographs revealed that the size of the as synthesized crystallites to be in\nthe 30 to 80 nm range. The powders so obtained had excellent sinterability\nresulting in high density ceramics which exhibited giant dielectric constants\nupto 40000 (1 kHz) at 25oC accompanied by low dielectric losses, less than\n0.07."
    },
    {
        "anchor": "Thermoplastic deformation of silicon surfaces induced by ultrashort\n  pulsed lasers in submelting conditions: A hybrid 2D theoretical model is presented to describe thermoplastic\ndeformation effects on silicon surfaces induced by single and multiple\nultrashort pulsed laser irradiation in submelting conditions. An approximation\nof the Boltzmann transport equation is adopted to describe the laser\nirradiation process. The evolution of the induced deformation field is\ndescribed initially by adopting the differential equations of dynamic\nthermoelasticity while the onset of plastic yielding is described by the von\nMise's stress. Details of the resulting picometre sized crater, produced by\nirradiation with a single pulse, are then discussed as a function of the\nimposed conditions and thresholds for the onset of plasticity are computed.\nIrradiation with multiple pulses leads to ripple formation of nanometre size\nthat originates from the interference of the incident and a surface scattered\nwave. It is suggested that ultrafast laser induced surface modification in\nsemiconductors is feasible in submelting conditions, and it may act as a\nprecursor of the incubation effects observed at multiple pulse irradiation of\nmaterials surfaces.",
        "positive": "Investigation of the anisotropic electron g factor as a probe of the\n  electronic structure of GaBi$_{x}$As$_{1-x}$/GaAs epilayers: The electron Land\\'e g factor ($g^{*}$) is investigated both experimentally\nand theoretically in a series of GaBi$_{x}$As$_{1-x}$/GaAs strained epitaxial\nlayers, for bismuth compositions up to $x = 3.8$%. We measure $g^{*}$ via\ntime-resolved photoluminescence spectroscopy, which we use to analyze the spin\nquantum beats in the polarization of the photoluminescence in the presence of\nan externally applied magnetic field. The experimental measurements are\ncompared directly to atomistic tight-binding calculations on large supercells,\nwhich allows us to explicitly account for alloy disorder effects. We\ndemonstrate that the magnitude of $g^{*}$ increases strongly with increasing Bi\ncomposition $x$ and, based on the agreement between the theoretical\ncalculations and experimental measurements, elucidate the underlying causes of\nthe observed variation of $g^{*}$. By performing measurements in which the\norientation of the applied magnetic field is changed, we further demonstrate\nthat $g^{*}$ is strongly anisotropic. We quantify the observed variation of\n$g^{*}$ with $x$, and its anisotropy, in terms of a combination of epitaxial\nstrain and Bi-induced hybridization of valence states due to alloy disorder,\nwhich strongly perturbs the electronic structure."
    },
    {
        "anchor": "Cooperative Effect of Electron Correlation and Spin-Orbit Coupling on\n  the Electronic and Magnetic Properties of Ba2NaOsO6: The electronic and magnetic properties of the cubic double perovskite\nBa2NaOsO6 were examined by performing first-principles density functional\ntheory calculations and analyzing spin-orbit coupled states of an Os7+ (d1) ion\nat an octahedral crystal field. The insulating behavior of Ba2NaOsO6 was shown\nto originate from a cooperative effect of electron correlation and spin-orbit\ncoupling. This cooperative effect is responsible not only for the absence of\norbital ordering in Ba2 NaOsO6 but also for a small magnetic moment and a weak\nmagnetic anisotropy in Ba2NaOsO6.",
        "positive": "Proton-fluence dependent magnetic properties of exfoliable quasi-2D van\n  der Waals Cr2Si2Te6 magnet: The discovery of long-range magnetic ordering in atomically thin materials\ncatapulted the van der Waals (vdW) family of compounds into an unprecedented\npopularity. In particular, with a current push in space exploration, it is\nbeneficial to study how the properties of such materials evolve under proton\nirradiation. Owing to their robust intra-layer stability and sensitivity to\nexternal perturbations, these materials provide excellent opportunities for\nstudying proton irradiation as a non-destructive tool for controlling their\nmagnetic properties. Specifically, the exfoliable Cr2Si2Te6 (CST) is a\nferromagnetic semiconductor with the Curie temperature (TC) of ~32 K. Here, we\nhave investigated the magnetic properties of CST upon proton irradiation as a\nfunction of fluence (1 x 1015, 5 x 1015, 1 x 1016, 5 x 1016, and 1 x 1018\nH+/cm2) by employing variable-temperature, variable-field magnetization\nmeasurements coupled with electron paramagnetic resonance (EPR) spectroscopy\nand detail how the magnetization, magnetic anisotropy and EPR spectral\nparameters vary as a function of proton fluence across the magnetic phase\ntransition. While the TC remains constant as a function of proton fluence, we\nobserved that the saturation magnetization and magnetic anisotropy diverge at\nthe proton fluence of 5 x 1016 H+/cm2, which is prominent in the ferromagnetic\nphase, in particular. This work demonstrates that proton irradiation is a\nfeasible method for modifying the magnetic properties and local magnetic\ninteractions of vdWs crystals, which represents a significant step forward in\nthe design of future spintronic and magneto-electronic applications."
    },
    {
        "anchor": "Kinetics-Controlled Degradation Reactions at Crystalline\n  LiPON/Li(x)CoO(2) and Crystalline LiPON/Li-metal Interfaces: Detailed understanding of solid-solid interface structure-function relations\nis critical for the improvement and wide deployment of all solid-state\nbatteries. The interfaces between lithium phosphorous oxynitride (\"LiPON\")\nsolid electrolyte material and lithium metal anode, between LiPON and\nLi(x)CoO(2) cathode surfaces, have been reported to generate solid electrolyte\ninterphase (\"SEI\")-like products and/or disordered regions. Using electronic\nstructure calculations and crystalline LiPON models with\natomic-layer-deposition-like stoichiometry, we predict LiPON models with purely\nP-N-P backbones are kinetically inert towards lithium at room temperature. In\ncontrast, transfer of oxygen atoms from low-energy Li(x)CoO(2) (104) surfaces\nto LiPON is much faster under ambient conditions. The mechanisms of the primary\nreaction steps, LiPON motifs that readily react with lithium metal,\nexperimental results on amorphous LiPON to partially corroborate these\npredictions, and possible mitigation strategies to reduce degradations are\ndiscussed. LiPON interfaces are found to be useful case studies for\nhighlighting the importance of kinetics-controlled processes during battery\nassembly at moderate processing temperatures.",
        "positive": "Effects of Temperature and Near Ultraviolet Light on Current-Voltage\n  Characteristics of Colemanite: We investigate current-voltage (I-V) characteristics of the ferroelectric\nmaterial colemanite at room temperature, at a high temperature, and also under\nthe influence of near ultraviolet light. We demonstrate that all three I-V\nplots exhibit hysteresis effects, and these new results shed new light on the\nresistance of colemanite. These novel properties are explained on the basis of\nits microstructure indicating potential applications in devices with negative\nresistance as well as in photovoltaic devices."
    },
    {
        "anchor": "High-throughput imaging measurements of thermoelectric figure of merit: We demonstrate a method for the simultaneous determination of the\nthermoelectric figure of merit of multiple martials by means of the lock-in\nthermography (LIT) technique. This method is based on the thermal analyses of\nthe transient temperature distribution induced by the Peltier effect and Joule\nheating, which enables high-throughput estimation of the thermal diffusivity,\nthermal conductivity, volumetric heat capacity, Seebeck or Peltier coefficient\nof the materials. The LIT-based approach has high reproducibility and\nreliability because it offers sensitive noncontact temperature measurements and\ndoes not require the installation of an external heater. By performing the same\nmeasurements and analyses with applying an external magnetic field, the\nmagnetic field and/or magnetization dependences of the Seebeck or Peltier\ncoefficient and thermal conductivity can be determined simultaneously. We\ndemonstrate the validity of this method by using several ferromagnetic metals\n(Ni, Ni$_{95}$Pt$_{5}$, and Fe) and a nonmagnetic metal (Ti). The proposed\nmethod will be useful for materials research in thermoelectrics and spin\ncaloritronics and for investigation of magneto-thermal and\nmagneto-thermoelectric transport properties.",
        "positive": "Iodide-methylammonium interaction is responsible for ferroelectricity in\n  CH3NH3PbI3: Excellent conversion efficiencies of over 20 % and facile cell production\nhave placed hybrid perovskites at the forefront of novel solar cell materials\nwith CH3NH3PbI3 being its archetypal compound. The question why CH3NH3PbI3 has\nsuch extraordinary characteristics, particularly a hugely efficient light\nabsorption, is hotly debated with ferroelectricity being a promising candidate.\nThis does, however, afford the crystal structure to be non-centrosymmetric and\nwe herein present crystallographic evidence as to how the symmetry breaking\noccurs on a crystallographic, and therefore long-scale, level. While the\nmolecular cation CH3NH3+ is intrinsically polar, it is heavily disordered and\ncannot be the sole reason for ferroelectricity. We show that it, nonetheless,\nplays an important role as it distorts the neighboring iodide positions from\ntheir centrosymmetric positions."
    },
    {
        "anchor": "Magneto-optical selection rules of curved graphene nanoribbons and\n  carbon nanotubes: We derive the generalized magneto-absorption spectra for curved graphene\nnanorib- bons and carbon nanotubes by using the Peierls tight-binding model.\nThe main spectral characteristics and the optical selection rules result from\nthe cooperative or competitive relationships between the geometric structure\nand a magnetic field. In curved ribbons, the dominant selection rule remains\nunchanged during the variation of the curvature. When the arc angle increases,\nthe prominent peaks are split, with some even vanishing as the angle exceeds a\ncritical value. In carbon nanotubes, the angular-momentum coupling induces\nextra selection rules, of which more are revealed due to the increase of either\n(both) of the factors: tube diameter and field strength. Particularly once the\ntwo factors exceed certain critical values, the optical spectra could reflect\nthe quasi-Landau-level structures. The identifying features of the spec- tra\nprovide insight into optical excitations for curved systems with either open or\nclosed boundary condition.",
        "positive": "Chemical mechanical polishing of thin film diamond: The demonstration that Nanocrystalline Diamond (NCD) can retain the superior\nYoung's modulus (1,100 GPa) of single crystal diamond twinned with its ability\nto be grown at low temperatures (<450 {\\deg}C) has driven a revival into the\ngrowth and applications of NCD thin films. However, owing to the competitive\ngrowth of crystals the resulting film has a roughness that evolves with film\nthickness, preventing NCD films from reaching their full potential in devices\nwhere a smooth film is required. To reduce this roughness, films have been\npolished using Chemical Mechanical Polishing (CMP). A Logitech Tribo CMP tool\nequipped with a polyurethane/polyester polishing cloth and an alkaline\ncolloidal silica polishing fluid has been used to polish NCD films. The\nresulting films have been characterised with Atomic Force Microscopy, Scanning\nElectron Microscopy and X-ray Photoelectron Spectroscopy. Root mean square\nroughness values have been reduced from 18.3 nm to 1.7 nm over 25 {\\mu}m$^2$,\nwith roughness values as low as 0.42 nm over ~ 0.25 {\\mu}m$^2$. A polishing\nmechanism of wet oxidation of the surface, attachment of silica particles and\nsubsequent shearing away of carbon has also been proposed."
    },
    {
        "anchor": "Unusual Magnetic Properties in Layered Magnetic Topological Insulator\n  EuSn2As2: EuSn2As2 with layered rhombohedral crystal structure is proposed to be a\ncandidate of intrinsic antiferromagnetic (AFM) topological insulator. Here, we\nhave investigated systematic magnetoresistance (MR) and magnetization\nmeasurements on the high quality EuSn2As2 single crystal with the magnetic\nfield both parallel and perpendicular to (00l) plane. Both the kink of magnetic\nsusceptibility and longitudinal resistivity reveal that EuSn2An2 undergoes an\nAFM transition at TN = 21 K. At T = 2 K, the magnetization exhibits two\nsuccessive plateaus of ~ 5.6 {\\mu}B/Eu and ~ 6.6 {\\mu}B/Eu at the corresponding\ncritical magnetic fields. Combined with the negative longitudinal MR and\nabnormal Hall resistance, we demonstrate that EuSn2An2 undergoes complicated\nmagnetic transitions from an AFM state to a canted ferromagnetic (FM) state at\nHc and then to a polarized FM state at Hs as the magnetic field increase.",
        "positive": "Size effect of soft phonon dispersion law in nanosized ferroics: Using Landau-Ginsburg-Devonshire theory, we derive and analyze analytical\nexpressions for the frequency dispersion of soft phonon modes in nanosized\nferroics and perform numerical calculations for a thin SrTiO3 film. We revealed\nthe pronounced \"true\" size effect in the dependence of soft phonon spatial\ndispersion on the film thickness and predict that it can lead to the \"apparent\"\nor \"false\" size effect of dynamic flexoelectric coupling constants"
    },
    {
        "anchor": "Fabrication of nanotubules of thermoelectric gamma-Na0.7CoO2 using\n  porous aluminum oxide membrane as supporting template: We report the successful synthesis of nanotubules of thermoelectric materials\ngamma-NaxCoO2 using two different sol-gel routes aided by porous anodized\naluminium oxide (AAO) membrane as supporting templates. The gamma-NaxCoO2\nnanotubule using urea-based route can be achieved at 650 degree C at a heating\nrate of 1 degree C/min and held for 4h. The gamma-NaxCoO2 nanotubule using\ncitric acid-based route can be achieved at 500 degree C using a rapid-heat-up\nprocedure and held for 30 min. The products were investigated using various\ntechniques including XRD, SEM and TEM. Electron diffraction pattern taken along\n[001] zone axis direction on the nanotubule shows that all the diffraction\nspots can be indexed using a hexagonal unit cell with a = b = 0.56 nm, which\ncan be considered as a superstructure with cell doubling within the ab plane.",
        "positive": "Triggering InAs/GaAs Quantum Dot nucleation and growth rate\n  determination by in-situ modulation of surface energy: Epitaxial InAs/GaAs Quantum Dots (QDs) are widely used as highly efficient\nand pure sources of single photons and entangled photon-pairs, however reliable\nwafer-scale growth techniques have proved elusive. Growth of two-dimensional\nQuantum Well (QW) thin-films can be achieved with atomic precision down to\nbelow the de Broglie wavelength of electrons in the material, exposing the\nquantum particle-in-a-box energy vs. thickness-squared relationship. However,\ndifficulties in controlling the exact moment of nanostructure nucleation\nobscure this behaviour in epitaxial QD material, preventing a clear\nunderstanding of their growth. In this work we demonstrate that QD nucleation\ncan be induced by directly modulating the crystal surface energy without\nadditional materials or equipment. This gains us quantitative measure of the QD\ngrowth rate and enables predictive design of QD growth processes. We believe\nthis technique will be crucial to the realisation of uniform arrays of QDs\nrequired for scalable quantum devices at the single-photon level."
    },
    {
        "anchor": "High phonon-limited mobility of BAs under pressure: Recent experiment reports that high thermal conductivity of ~1000 W/mK is\nobserved in cubic boron arsenide crystal (BAs). In order to expand the scope of\nfuture applications, we use first-principles calculations to investigate the\nphonon-limited electronic transport in BAs family and modulation effect of\npressure. In the case of electron doping, BAs, AlAs and AlSb exhibit the\ncoupling between high frequency optical phonons and electron as well as the low\nfrequency acoustical phonons in BSb. And BAs has the weakest electron-phonon\ncoupling thus has a high N-type carrier mobility of 1740 cm^2/Vs. After the\nintroduction of pressure, phonon spectra has more obvious change than the\nelectronic structure. The phonon hardening under the pressure gives rise to the\nweakening of electron-phonon coupling. It is obtained that the pressure of 50\nGPa can improve the mobility of BAs up to 4300 cm^2/Vs, which is much high and\ngreat significance to the current semiconductor industry.",
        "positive": "Freezing as a path to build complex composites: Materials that are strong, ultra-light weight and tough are in demand for a\nrange of applications, requiring architectures and components carefully\ndesigned from the micrometer down to nanometer scales. Nacre-a structure found\nin many molluscan shells-and bone are frequently used as examples for how\nnature achieves this through hybrid organic-inorganic composites.\nUnfortunately, it has proven extremely difficult to transcribe nacre-like\nclever designs into synthetic materials, partly because their intricate\nstructures need to be replicated at several length scales. We demonstrate how\nthe physics of ice formation can be used to develop sophisticated porous and\nlayered-hybrid materials, including artificial bone, ceramic/metal composites,\nand porous scaffolds for osseous tissue regeneration with strengths up to four\ntimes higher than those currently used for implantation."
    },
    {
        "anchor": "Defects, Tunneling, and EPR Spectra of Single-Molecule Magnets: We examine theoretically electron paramagnetic resonance (EPR) lineshapes as\nfunctions of resonance frequency, energy level, and temperature for single\ncrystals of three different kinds of single-molecule nanomagnets (SMMs):\nMn$_{12}$ acetate, Fe$_8$Br, and the $S=9/2$ Mn$_4$ compound. We use a\ndensity-matrix equation and consider distributions in the uniaxial\n(second-order) anisotropy parameter $D$ and the $g$ factor, caused by possible\ndefects in the samples. Additionally, weak intermolecular exchange and\nelectronic dipole interactions are included in a mean-field approximation. Our\ncalculated linewidths are in good agreement with experiments. We find that the\ndistribution in $D$ is common to the three examined single-molecule magnets.\nThis could provide a basis for a proposed tunneling mechanism due to lattice\ndefects or imperfections. We also find that weak intermolecular exchange and\ndipolar interactions are mainly responsible for the temperature dependence of\nthe lineshapes for all three SMMs, and that the intermolecular exchange\ninteraction is more significant for Mn$_4$ than for the other two SMMs. This\nfinding is consistent with earlier experiments and suggests the role of\nspin-spin relaxation processes in the mechanism of magnetization tunneling.",
        "positive": "Spin transfer in an antiferromagnet: An electrical current can transfer spin angular momentum to a ferromagnet.\nThis novel physical phenomenon, called spin transfer, offers unprecedented\nspatial and temporal control over the magnetic state of a ferromagnet and has\ntremendous potential in a broad range of technologies, including magnetic\nmemory and recording. Recently, it has been predicted that spin transfer is not\nlimited to ferromagnets, but can also occur in antiferromagnetic materials and\neven be stronger under some conditions. In this paper we demonstrate transfer\nof spin angular momentum across an interface between ferromagnetic and\nantiferromagnetic metals. The spin transfer is mediated by an electrical\ncurrent of high density (~10^12 A/m^2) and revealed by variation in the\nexchange bias at the ferromagnet/antiferromagnet interface. We find that,\ndepending on the polarity of the electrical current flowing across the\ninterface, the strength of the exchange bias can either increase or decrease.\nThis finding is explained by the theoretical prediction that a spin polarized\ncurrent generates a torque on magnetic moments in the antiferromagnet.\nCurrent-mediated variation of exchange bias can be used to control the magnetic\nstate of spin-valve devices, e.g., in magnetic memory applications."
    },
    {
        "anchor": "Phonon Kinetics at the Solid to Liquid Phase Transition: Terahertz time domain spectroscopy (THz TDS) is used to measure the melting\nkinetics of fructose molecular crystals. Combining single crystal anisotropy\nmeasurements with density functional calculations we assign the phonon\nfrequencies and interrogate how specific phonons behave with melting. While\nnearly all the low frequency phonons continuously red shift with heating and\nmelting, the lowest energy phonon polarized along the c-axis blue shifts at the\nmelting temperature, suggesting an initial structural change immediately before\nmelting. We find that the kinetics follow a 3D growth model with large\nactivation energies consistent with previous differential scanning calorimetry\n(DSC) measurements. The large activation energies indicate multiple H-bonds\nmust break collectively for the transition. The results suggest the generality\nof the kinetics for molecular crystals and that THz TDS with picosecond\nresolution could be used to measure ultra-fast kinetics.",
        "positive": "Epitaxial Mn5Ge3 (100) layer on Ge(100) substrates obtained by flash\n  lamp annealing: Mn5Ge3 thin films have been demonstrated as a promising spin-injector\nmaterial for germanium-based spintronic devices. So far, Mn5Ge3 has been grown\nepitaxially only on Ge (111) substrates. In this letter we present the growth\nof epitaxial Mn5Ge3 films on Ge (100) substrates. The Mn5Ge3 film is\nsynthetized via sub-second solid-state reaction between Mn and Ge upon flash\nlamp annealing for 20 ms at the ambient pressure. The single crystalline Mn5Ge3\nis ferromagnetic with a Curie temperature of 283 K. Both the c-axis of\nhexagonal Mn5Ge3 and the magnetic easy axis are parallel to the Ge (100)\nsurface. The millisecond-range flash epitaxy provides a new avenue for the\nfabrication of Ge-based spin-injectors fully compatible with CMOS technology."
    },
    {
        "anchor": "Enhancing the limit of uniaxial magnetic anisotropy induced by ion beam\n  erosion: The artificial tailoring of magnetic anisotropy by manipulation of\ninterfacial morphology and film structure are of fundamental interest from\napplication point of view in spintronic and magnetic memory devices. This\nletter reports an approach of engineering and enhancing the strength of oblique\nincidence ion beam erosion (IBE) induced in-plane uniaxial magnetic anisotropy\n(UMA) by simultaneous modification of film morphology as well as film texture.\nTo meet this objective, Cobalt film and Si substrate have been taken as a model\nsystem. Unlike conventional post growth IBE of film, we direct our effort to\nthe sequential deposition and subsequent IBE of the film. Detailed in-situ\ninvestigation insights that the film grows in highly biaxially textured\npolycrystalline state with formation of nanometric surface ripples. The film\nalso exhibits pronounced UMA with easy axis oriented parallel to the surface\nripple direction. Remarkably, the induced UMA is about one order of magnitude\nlarger than the reported similar kind of earlier studies. The possibility of\nimposing in-plane crystallographic texture giving rise to magneto-crystalline\nanisotropy, along with long-range dipolar interaction throughout ripple crests\nenhances the strength of the UMA. The present findings can be further extended\nto systems characterized by different crystallographic structure and magnetic\nproperties and show the general applicability of the present method.",
        "positive": "Direct demonstration of topological stability of magnetic skyrmions via\n  topology manipulation: Topological protection precludes a continuous deformation between\ntopologically inequivalent configurations in a continuum. Motivated by this\nconcept, magnetic skyrmions, topologically nontrivial spin textures, are\nexpected to exhibit the topological stability, thereby offering a prospect as a\nnanometer-scale non-volatile information carrier. In real materials, however,\natomic spins are configured as not continuous but discrete distribution, which\nraises a fundamental question if the topological stability is indeed preserved\nfor real magnetic skyrmions. Answering this question necessitates a direct\ncomparison between topologically nontrivial and trivial spin textures, but the\ndirect comparison in one sample under the same magnetic fields has been\nchallenging. Here we report how to selectively achieve either a skyrmion state\nor a topologically trivial bubble state in a single specimen and thereby show\nhow robust the skyrmion structure is in comparison with the bubbles for the\nfirst time. We demonstrate that topologically nontrivial magnetic skyrmions\nshow longer lifetimes than trivial bubble structures, evidencing the\ntopological stability in a real discrete system. Our work corroborates the\nphysical importance of the topology in the magnetic materials, which has\nhitherto been suggested by mathematical arguments, providing an important step\ntowards ever-dense and more-stable magnetic devices."
    },
    {
        "anchor": "Synthesis and Structural Characterization of Highly Tetragonal\n  (1-x)Bi(Zn1/2Ti1/2)O3-xPbTiO3 Piezoceramics: We present here the comprehensive X-ray diffraction (XRD) and dielectric\nmeasurement of (1-x)Bi(Zn1/2Ti1/2)O3-xPbTiO3 (BZT-xPT) piezoceramics with\nx=0.65, 0.70, 0.75 and 0.80. Powder X-ray diffraction data reveals the\ntetragonal structure (space group P4mm) of BZT-xPT ceramics for all the\ncompositions.",
        "positive": "Recent Progress of Multiferroic Perovskite Manganites: Many multiferroic materials, with various chemical compositions and crystal\nstructures, have been discovered in the past years. Among these multiferroics,\nsome perovskite manganites with ferroelectricity driven by magnetic orders are\nof particular interest. In these multiferroic perovskite manganites, not only\ntheir multiferroic properties are quite prominent, but also the involved\nphysical mechanisms are very plenty and representative. In this Brief Review,\nwe will introduce some recent theoretical and experimental progress on\nmultiferroic manganites."
    },
    {
        "anchor": "Band Unfolding Made Simple: We present a simple view on band unfolding of the energy bands obtained from\nsupercell calculations. It relies on the relationship between the local density\nof states in reciprocal space (qLDOS) and the fully unfolded band structure.\nThis provides an intuitive and valid approach not only for periodic, but also\nfor systems with no translational symmetry. By refolding into the primitive\nBrillouin zone of the pristine crystal we recover the conventional unfolded\nbands. We implement our algorithm in the SIESTA package and apply it to defects\non Si and graphene.",
        "positive": "Electronic band structure and carrier effective mass in calcium\n  aluminates: First-principles electronic band structure investigations of five compounds\nof the CaO-Al2O3 family, 3CaO.Al2O3, 12CaO.7Al2O3, CaO.Al2O3, CaO.2Al2O3 and\nCaO.6Al2O3, as well as CaO and alpha-, theta- and kappa-Al2O3 are performed. We\nfind that the conduction band in the complex oxides is formed from the oxygen\nantibonding p-states and, although the band gap in Al2O3 is almost twice larger\nthan in CaO, the s-states of both cations. Such a hybrid nature of the\nconduction band leads to isotropic electron effective masses which are nearly\nthe same for all compounds investigated. This insensitivity of the effective\nmass to variations in the composition and structure suggests that upon a proper\ndegenerate doping, both amorphous and crystalline phases of the materials will\npossess mobile extra electrons."
    },
    {
        "anchor": "Absolute negative refraction and imaging of unpolarized electromagnetic\n  waves by two-dimensional photonic crystals: Absolute negative refraction regions for both polarizations of\nelectromagnetic wave in two-dimensional photonic crystal have been found\nthrough both the analysis and the exact numerical simulation. Especially,\nabsolute all-angle negative refraction for both polarizations has also been\ndemonstrated. Thus, the focusing and image of unpolarized light can be realized\nby a microsuperlens consisting of the two-dimensional photonic crystals. The\nabsorption and compensation for the losses by introducing optical gain in these\nsystems have also been discussed.",
        "positive": "Structural and transport properties of\n  La$_{1-x}$Sr$_x$Co$_{1-y}$Nb$_y$O$_3$ thin films: We present the structural and transport properties of\nLa$_{1-x}$Sr$_x$Co$_{1-y}$Nb$_y$O$_3$ ($y=$ 0.1 and $x=$ 0; $y=$ 0.15 and $x=$\n0.3) thin films grown on (001) orientated single crystalline ceramic substrates\nto investigate the effect of lattice induced compressive and tensile strain.\nThe high resolution x-ray diffraction measurements, including\n$\\theta$-2$\\theta$ scan, $\\Phi$-scan, and reciprocal space mapping, affirm\nsingle phase; four-fold symmetry; good quality of deposited thin films. The\natomic force micrographs confirm that these films have small root mean square\nroughness in the range of $\\sim$0.5--7~nm. We observed additional Raman active\nmodes in the films owing to the lowered crystal symmetry as compared to the\nbulk. More interestingly, the temperature dependent dc-resistivity measurements\nreveal that films become insulating due to induced lattice strain in comparison\nto bulk, however for the larger compressive strained films conductivity\nincrease significantly owing to the higher degree of $p-d$ hybridization and\nreduction in bandwidth near the Fermi level."
    },
    {
        "anchor": "Formation of a p-n junction on the GaAs-surface by an Ar+ ion beam: The core-level and valence band electronic structure of the well-defined\nnear-surface layer of n-GaAs (100) has been studied by synchrotron-based\nhigh-resolution photoelectron spectroscopy before and after modification of the\nlayer by an Ar+ ion beam in the 1.5 - 2.5 keV energy range. Conversion of the\nconductivity type from n into p has been revealed in the irradiated layer\nseveral nm thick. The effect manifests itself in shifts of the core-levels and\nvalence band edge by the value comparable to the bandgap width. Transformation\non the conductivity type has been assumed to be caused by Ga-antisite point\ndefects generated by ion bombardment. The possibility of local formation of a\np-n nanojunction within the ion-beam spot has been shown.",
        "positive": "Crystallization of Supercooled Liquid Elements Induced by Superclusters\n  Containing Magic Atom Numbers: A few experiments have already detected the presence of icosahedral\nsuperclusters in undercooled liquids, confirming a possible homogeneous\nnucleation of such entities as suggested by Franck. These superclusters survive\nin melts above the crystal melting temperature Tm because all their surface\natoms have the same fusion heat as their core atoms and are melted by\nhomogeneous nucleation of liquid in their core, depending on overheating time\nand temperature. In complete contrast to current ideas, a long time is\nnecessary to melt them and to attain the thermodynamic equilibrium above Tm.\nThey act as heterogeneous growth nuclei of crystallized phase at a temperature\nTc of the undercooled melt when they are not melted. They contribute to the\nreduction of the critical barrier, which becomes smaller than that of crystals\ncontaining the same atom number n. The undercooling rate is always limited,\neven in a liquid at thermodynamic equilibrium, because the homogeneous\nnucleation of 13-atom superclusters reduces the energy barrier, and increases\nTc above the homogeneous nucleation temperature equal to Tm/3 in liquid\nelements. After weak superheating, the most stable superclusters containing n =\n13, 55, 147, 309 and 561 atoms survive or melt and determine Tc during\nundercooling, which depends on n and on the sample volume. The experimental\nnucleation temperatures Tc of 32 liquid elements and the melting temperatures\nof superclusters are predicted without any adjustable parameter using a sample\nvolume varying by nearly 18 orders of magnitude. The classical Gibbs free\nenergy change is used, adding an enthalpy saving related to the Laplace\npressure change associated with supercluster formation, which is quantified and\nstrongly weakened for n = 13 and 55."
    },
    {
        "anchor": "Role of zero-point effects in stabilizing the ground state structure of\n  bulk Fe2P: Structural stability of Fe2P is investigated in detail using first-principles\ncalculations based on density functional theory. While the orthorhombic C23\nphase is found to be energetically more stable, the experiments suggest it to\nbe hexagonal C22 phase. In the present study, we show that in order to obtain\nthe correct ground state structure of Fe2P from the first-principles based\nmethods it is utmost necessary to consider the zero-point effects such as\nzero-point vibrations and spin fluctuations. This study demonstrates an\nexceptional case where a bulk material is stabilized by quantum effects, which\nare usually important in low-dimensional materials. Our results also indicate\nthe possibility of magnetic field induced structural quantum phase transition\nin Fe2P, which should form the basis for further theoretical and experimental\nefforts.",
        "positive": "Mechanism and Kinetics of Na+ Ion Depletion under the Anode during\n  Electro-thermal Poling of a Bioactive Glass: Electro-thermal poling experiments were carried out on a bioactive glass, and\nthe kinetics of the Na+ ion depletion layer formation under the anode was\nstudied in-situ by means of ac impedance spectroscopy. One important finding is\na linear relation between the depletion layer thickness and the applied\nvoltage, which is in contrast to the predictions of standard space charge\ntheory. The average electric field in the layer is independent of the voltage\nand is close to the dielectric breakdown field of alkali ion conducting\nglasses. Furthermore, we observe that the thickness of the depletion layer is\nestablished on a much shorter time scale than the resistance. We explain these\nresults by assuming that the huge electric fields created under the anode\nduring Na+ ion depletion lead to a strong increase of the electronic mobility\nin the layer and to charge compensation via extraction of electrons. It is\nshown that in the initial stages of the depletion process, a relative Na+ ion\ndepletion of only 400 ppm is sufficient to generate electric fields of the\norder of the dielectric breakdown field."
    },
    {
        "anchor": "Elastic Boundary Conditions in the Theory with Second Gradients in the\n  Thermodynamic Potential: When describing elastic deformations of a body sometimes it is worth to take\nin account elastic spatial dispersion. If spatial dispersion is weak, as\nusually happens, then it can be reduced to dependence of thermodynamic\npotential on strain gradients. Such a dependence may be worth in association\nwith small body size which imply large gradients. Besides, the inclusion of\nthis dispersion leads to physical phenomena absent without it. An example of\nthe latter is flexoelectricity. Remarkable fact is that while the derivation of\ndifferential equations of elastic equilibrium can be made by ordinary means in\nthis case, the derivation of boundary conditions for them is less trivial task.\nThis is due to the fact that strain gradients should be represented in terms of\nsecond gradients of independently varied elastic displacements. Detailed\nconsideration of this problem is the subject of this paper.",
        "positive": "Analytic model of the remobilization of pinned glide dislocations:\n  including dislocation drag from phonon wind: In this paper we discuss the effect of a non-constant dislocation drag\ncoefficient on the very high strain rate regime within an analytic model\ndescribing mobile-immobile dislocation intersections applicable to\npolycrystals. Based on previous work on dislocation drag, we estimate its\ntemperature and pressure dependence and its effects on stress-strain rate\nrelations. In the high temperature regime, we show that drag can remain the\ndominating effect even down to intermediate strain rates. We also discuss the\nconsequences of having a limiting dislocation velocity, a feature which is\ntypically predicted by analytic models of dislocation drag, but which is\nsomewhat under debate because a number of MD simulations predict supersonic\ndislocations."
    },
    {
        "anchor": "Electric field gradients in Zr$_8$Ni$_{21}$ and Hf$_8$Ni$_{21}$\n  intermetallic compounds; Results from perturbed angular correlation\n  measurements and first-principles density functional theory: Numerous technological applications of Ni-based Zr and Hf intermetallic\nalloys promoted comprehensive studies in Zr$_8$Ni$_{21}$ and Hf$_8$Ni$_{21}$ by\nperturbed angular correlation (PAC) spectroscopy, which were not studied\nearlier until this report. The different phases produced in the samples have\nbeen identified by PAC and X-ray diffraction (XRD) measurements. Using\n$^{181}$Hf probe, two non-equivalent Zr/Hf sites have been observed in both\nZr$_8$Ni$_{21}$ and Hf$_8$Ni$_{21}$ compounds. From present PAC measurements in\nZr$_8$Ni$_{21}$, a component due to the production of Zr$_7$Ni$_{10}$ by\neutectic reaction from the liquid metals is also observed. The phase\nZr$_7$Ni$_{10}$, however, is not found from the XRD measurement. In\nZr$_8$Ni$_{21}$, while the results do not change appreciably up to 973 K\nexhibit drastic changes at 1073 K. In Hf$_8$Ni$_{21}$, similar results for the\ntwo non-equivalent sites have been found but site fractions are in reverse\norder. In this alloy, a different contaminating phase, possibly due to\nHfNi$_3$, has been found from PAC measurements but is not found from XRD\nmeasurement. Density functional theory (DFT) based calculations of electric\nfield gradient (EFG) and asymmetry parameter ($\\eta$) at the sites of\n$^{181}$Ta probe nucleus allowed us to assign the observed EFG fractions to the\nvarious lattice sites in (Zr/Hf)$_8$Ni$_{21}$ compounds.",
        "positive": "Thermophysical properties for shock compressed polystyrene: We have performed quantum molecular dynamic simulations for warm dense\npolystyrene at high pressures. The principal Hugoniot up to 790 GPa is derived\nfrom wide range equation of states, where contributions from atomic ionizations\nare semiclassically determined. The optical conductivity is calculated via the\nKubo-Greenwood formula, from which the dc electrical conductivity and optical\nreflectivity are determined. The nonmetal-to-metal transition is identified by\ngradual decomposition of the polymer. Our results show good agreement with\nrecent high precision laser-driven experiments."
    },
    {
        "anchor": "Unraveling the varied nature and roles of defects in hybrid halide\n  perovskites with time-resolved photoemission electron microscopy: With rapidly growing photoconversion efficiencies, hybrid perovskite solar\ncells have emerged as promising contenders for next generation, low-cost\nphotovoltaic technologies. Yet, the presence of nanoscale defect clusters, that\nform during the fabrication process, remains critical to overall device\noperation, including efficiency and long-term stability. To successfully deploy\nhybrid perovskites, we must understand the nature of the different types of\ndefects, assess their potentially varied roles in device performance, and\nunderstand how they respond to passivation strategies. Here, by correlating\nphotoemission and synchrotron-based scanning probe X-ray microscopies, we\nunveil three different types of defect clusters in state-of-the-art triple\ncation mixed halide perovskite thin films. Incorporating ultrafast\ntime-resolution into our photoemission measurements, we show that defect\nclusters originating at grain boundaries are the most detrimental for\nphotocarrier trapping, while lead iodide defect clusters are relatively benign.\nHexagonal polytype defect clusters are only mildly detrimental individually,\nbut can have a significant impact overall if abundant in occurrence. We also\nshow that passivating defects with oxygen in the presence of light, a\npreviously used approach to improve efficiency, has a varied impact on the\ndifferent types of defects. Even with just mild oxygen treatment, the grain\nboundary defects are completely healed, while the lead iodide defects begin to\nshow signs of chemical alteration. Our findings highlight the need for\nmulti-pronged strategies tailored to selectively address the detrimental impact\nof the different defect types in hybrid perovskite solar cells.",
        "positive": "Epitaxial GaN Nanorods via Catalytic Capillary Condensation: Intrinsic catalytic process by capillary condensation of Ga-atoms into\nnanotrenches, formed among impinging islands during the wurzite-GaN thin film\ndeposition, is shown to be an effective path to growing GaN nanorods without\nmetal catalysts. The nano-capillary brings within it a huge imbalance in\nequilibrium partial pressure of Ga relative to the growth ambient. GaN nanorods\nthus always grow out of a holding nanotrench and conform to the boundaries of\nsurrounding islands. The nanorods are epitaxially orientated with <0001>GaN //\n<111>Si and <2110>GaN // <110>Si similar to the matrix. Concaved geometry is\nessential and is a condition that limits the axial dimension of the nanorods\nprotruding above the base (matrix) material region. Revelation of the growth\nmechanism in the current context suggests that fabrication of nano quantum\nstructures with controlled patterns is enabling for any attainable dimensions"
    },
    {
        "anchor": "Coupled Dislocations and Fracture dynamics at finite deformation: model\n  derivation, and physical questions: A continuum mechanical model of coupled dislocation based plasticity and\nfracture at finite deformation is proposed. Motivating questions and target\napplications of the model are sketched.",
        "positive": "Composition-independent temperature induced by swift heavy ions in\n  insulators and its relation with track formation: A systematic study of the $R_e$-$T_m$ relation ($R_e$ = track radius, $T_m$ =\nmelting temperature) in insulators reveals new features of track formation. A\nquantitative relationship is demonstrated between $R_e$ values measured in\nvarious solids when $\\langle s_e\\rangle$=constant ($\\langle s_e\\rangle$ =\natomic stopping power). This effect is the consequence of a\ncomposition-independent, identical maximum temperature distribution $\\Delta\nT(r,0)$, which is induced in various insulators in a narrow cylindrical volume\nclose to the tracks. The uniformity ceases gradually at larger distances.\n$\\Delta T(r,0)$ has a Gaussian shape, with a constant width w=4.5 nm, is\nindependent of materials parameters and it can be determined experimentally by\nthe measurement of Re in various insulators when $\\langle s_e\\rangle$=constant.\nThe consequences of the experimental $\\Delta T(r,0)$ distribution are\ndiscussed."
    },
    {
        "anchor": "Ferroelectricity in oxyfluoride Aurivillius phase Bi$_2$TiO$_4$F$_2$\n  from first-principles: Using first-principle calculations, we restrained the m=1 oxyfluoride\nAurivillius Bi$_2$TiO4F$_2$ to adopt three ordered key configurations, such as\ntetragonal $I4/mmm$ phases with fluorine anions distributed either at the\noctahedral apical sites or at the octahedral equatorial ones and orthorhombic\n$Pma2$ phase with fluorine anions distributed over both apical and equatorial\nsites. We explored the energetics of the metastable phases and their potential\nfor ferroelectricity and found that the least favorable configuration is\nequatorial sites for fluorine and the most favorable one is the mixture between\napical and equatorial sites for fluorine. Phonon calculations performed in the\ntetragonal $I4/mmm$ with fluorine at the apical sites showed a strong c-axis\npolar instability $\\Gamma_{3}^{-}$ that co-exists with the ab-plane polar\ninstability $\\Gamma_{5}^{-}$, commonly found in Aurivillius oxide phases. These\ntwo polar instabilities lead to $Pc$ phase that displays in-plane and\nout-of-plane spontaneous polarizations as large as 44 $\\mu$c/cm$^{2}$ and 35\n$\\mu$c/cm$^{2}$, respectively, opening new prospective design in thin films\nAurivillius FeRAM devices.",
        "positive": "Symmetry and magnetically driven ferroelectricity in rare-earth\n  manganites RMnO3 (R=Gd, Tb, Dy): This work investigates the magnetically driven ferroelectricity in\northorhombic manganites RMnO3 (R=Gd, Dy or Tb) from the point of view of the\nsymmetry. The method adopted generalizes the one used to characterize the polar\nproperties of displacive modulated structures to the case of an irreducible\nmagnetic order parameter. The symmetry conditions for magnetically induced\nferroelectricity are established and the Landau-Devonshire free energy\nfunctionals derived from general symmetry considerations. The ferroelectric\npolarisation observed in DyMnO3 and TbMnO3 at zero magnetic field is explained\nin terms of the symmetry of a reducible magnetic order parameter. The\npolarisation rotation induced in these compounds by external magnetic fields\nand the stabilization of a ferroelectric phase in GdMnO3 are accounted for by a\nmechanism in which magnetization and polarization are secondary order\nparameters that are not directly coupled but compete with each other through\ntheir coupling to competing primary modulated order parameters."
    },
    {
        "anchor": "Magnon-mediated interlayer coupling in an all-antiferromagnetic junction: The interlayer coupling mediated by fermions in ferromagnets brings about\nparallel and anti-parallel magnetization orientations of two magnetic layers,\nresulting in the giant magnetoresistance, which forms the foundation in\nspintronics and accelerates the development of information technology. However,\nthe interlayer coupling mediated by another kind of quasi-particle, boson, is\nstill lacking. Here we demonstrate such a static interlayer coupling at room\ntemperature in an antiferromagnetic junction Fe2O3/Cr2O3/Fe2O3, where the two\nantiferromagnetic Fe2O3 layers are functional materials and the\nantiferromagnetic Cr2O3 layer serves as a spacer. The N\\'eel vectors in the top\nand bottom Fe2O3 are strongly orthogonally coupled, which is bridged by a\ntypical bosonic excitation (magnon) in the Cr2O3 spacer. Such an orthogonally\ncoupling exceeds the category of traditional collinear interlayer coupling via\nfermions in ground state, reflecting the fluctuating nature of the magnons, as\nsupported by our magnon quantum well model. Besides the fundamental\nsignificance on the quasi-particle-mediated interaction, the strong coupling in\nan antiferromagnetic magnon junction makes it a realistic candidate for\npractical antiferromagnetic spintronics and magnonics with ultrahigh-density\nintegration.",
        "positive": "Statistical Aging and Non Ergodicity in the Fluorescence of Single\n  Nanocrystals: The relation between single particle and ensemble measurements is adressed\nfor semiconductor CdSe nanocrystals. We record their fluorescence at the single\nmolecule level and analyse their emission intermittency, which is governed by\nunusual random processes known as Levy statistics. We report the observation of\nstatistical aging and ergodicity breaking, both related to the occurrence of\nLevy statistics. Our results show that the behaviour of ensemble quantities,\nsuch as the total fluorescence of an ensemble of nanocrystals, can differ from\nthe time averaged individual quantities, and must be interpreted with care."
    },
    {
        "anchor": "Three-Dimensional Nanoporous Graphene Substrate for Surface-Enhanced\n  Raman Scattering: We synthesized three-dimensional nanoporous graphene films by a chemical\nvapor deposition method with nanoporous copper as a catalytic substrate. The\nresulting nanoporous graphene has the same average pore size as the underlying\ncopper substrate. Our surface-enhanced Raman scattering (SERS) investigation\nindicates that the nanoporosity of graphene significantly improves the SERS\nefficiency of graphene as a substrate as compared to planar graphene\nsubstrates.",
        "positive": "Current-voltage characteristics of graphene devices: interplay between\n  Zener-Klein tunneling and defects: We report a theoretical/experimental study of current-voltage characteristics\n(I-V) of graphene devices near the Dirac point. The I-V can be described by a\npower law (I \\propto V^\\alpha, with 1< \\alpha <= 1.5). The exponent is higher\nwhen the mobility is lower. This superlinear I-V is interpreted in terms of the\ninterplay between Zener-Klein transport, that is tunneling between different\nenergy bands, and defect scattering. Surprisingly, the Zener-Klein tunneling is\nmade visible by the presence of defects."
    },
    {
        "anchor": "Magnetic ground state of semiconducting transition metal trichalcogenide\n  monolayers: Layered transition metal trichalcogenides with the chemical formula $ABX_3$\nhave attracted recent interest as potential candidates for two-dimensional\nmagnets. Using first-principles calculations within density functional theory,\nwe investigate the magnetic ground states of monolayers of Mn- and Cr-based\nsemiconducting trichalcogenides. We show that the second and third\nnearest-neighbor exchange interactions ($J_2$ and $J_3$) between magnetic ions,\nwhich have been largely overlooked in previous theoretical studies, are crucial\nin determining the magnetic ground state. Specifically, we find that monolayer\n$\\text{CrSiTe}_3$ is an antiferromagnet with a zigzag spin texture due to\nsignificant contribution from $J_3$, whereas $\\text{CrGeTe}_3$ is a ferromagnet\nwith a Curie temperature of 106 K. Monolayers of Mn-compounds ($\\text{MnPS}_3$\nand $\\text{MnPSe}_3$) always show antiferromagnetic Neel order. We identify the\nphysical origin of various exchange interactions, and demonstrate that strain\ncan be an effective knob for tuning the magnetic properties. Possible magnetic\nordering in the bulk is also discussed. Our study suggests that $\\text{ABX}_3$\ncan be a promising platform to explore 2D magnetic phenomena.",
        "positive": "Notch Fracture predictions using the Phase Field method for Ti-6Al-4V\n  produced by Selective Laser Melting after different post-processing\n  conditions: Ti-6Al-4V is a titanium alloy with excellent properties for lightweight\napplications and its production through Additive Manufacturing processes is\nattractive for different industrial sectors. In this work, the influence of\nmechanical properties on the notch fracture resistance of Ti-6Al-4V produced by\nSelective Laser Melting is numerically investigated. Literature data is used to\ninform material behaviour. The as-built brittle behaviour is compared to the\nenhanced ductile response after heat treatment (HT) and hot isostatic pressing\n(HIP) post-processes. A Phase Field framework is adopted to capture damage\nnucleation and propagation from two different notch geometries and a discussion\non the influence of fracture energy and the characteristic length is carried\nout. In addition, the influence of oxygen uptake is analysed by reproducing\nnon-inert atmospheres during HT and HIP, showing that oxygen shifts fracture to\nbrittle failures due to the formation of an alpha case layer, especially for\nthe V-notch geometry. Results show that a pure elastic behaviour can be assumed\nfor the as-built SLM condition, whereas elastic-plastic phenomena must be\nmodelled for specimens subjected to heat treatment or hot isostatic pressing.\nThe present brittle Phase Field framework coupled with an elastic-plastic\nconstitutive analysis is demonstrated to be a robust prediction tool for notch\nfracture after different post-processing routes."
    },
    {
        "anchor": "Damped reaction field method and the accelerated convergence of the real\n  space Ewald summation: In this paper we study a general theoretical framework which allows to\napproximate the real space Ewald sum by means of effective force shifted\nscreened potentials, together with a self term. Using this strategy it is\npossible to generalize the reaction field method, as a means to approximate the\nreal space Ewald sum. We show that this method exhibits faster convergence of\nthe Coulomb energy than several schemes proposed recently in the literature\nwhile enjoying a much more sound and clear electrostatic significance. In terms\nof the damping parameter of the screened potential, we are able to identify two\nclearly distinct regimes of convergence. Firstly, a reaction field regime\ncorresponding to the limit of small screening, where effective pair potentials\nconverge faster than the Ewald sum. Secondly, an Ewald regime, where the plain\nreal space Ewald sum converges faster. Tuning the screening parameter for\noptimal convergence occurs essentially at the crossover. The implication is\nthat effective pair potentials are an alternative to the Ewald sum only in\nthose cases where optimization of the convergence error is not possible.",
        "positive": "Quality factor due to roughness scattering of shear horizontal surface\n  acoustic waves in nanoresonators: In this work we study the quality factor associated with dissipation due to\nscattering of shear horizontal surface acoustic waves by random self-affine\nroughness. It is shown the quality factor is strongly influenced by both the\nsurface roughness exponent H, and the roughness amplitude w to lateral\ncorrelation length X ratio. Indeed, quality factors for roughness exponents\nH>0.5 are comparable to quality factors due to intrinsic dissipation mechanisms\n(e.g., thermoelastic losses and phonon-phonon scattering) especially for wave\nvectors <1/X. Our results indicate that this dissipation mechanism should be\ncarefully considered in the design micro/nanoelectromechanical systems."
    },
    {
        "anchor": "Reducing symmetry in topology optimization of two-dimensional porous\n  phononic crystals: In this paper we present a comprehensive study on the multi-objective\noptimization of two-dimensional porous phononic crystals (PnCs) in both square\nand triangular lattices with the reduced topology symmetry of the unit-cell.\nThe fast non-dominated sorting-based genetic algorithm II is used to perform\nthe optimization, and the Pareto-optimal solutions are obtained. The results\ndemonstrate that the symmetry reduction significantly influences the optimized\nstructures. The physical mechanism of the optimized structures is analyzed.\nTopology optimization combined with the symmetry reduction can discover new\nstructures and offer new degrees of freedom to design PnC-based devices.\nEspecially, the rotationally symmetrical structures presented here can be\nutilized to explore and design new chiral metamaterials.",
        "positive": "Exploiting ITO colloidal nanocrystals for ultrafast pulse generation: Dynamical materials that capable of responding to optical stimuli have always\nbeen pursued for designing novel photonic devices and functionalities, of which\nthe response speed and amplitude as well as integration adaptability and energy\neffectiveness are especially critical. Here we show ultrafast pulse generation\nby exploiting the ultrafast and sensitive nonlinear dynamical processes in\ntunably solution-processed colloidal epsilon-near-zero (ENZ) transparent\nconducting oxide (TCO) nanocrystals (NCs), of which the potential respond\nresponse speed is >2 THz and modulation depth is ~23% pumped at ~0.7 mJ/cm2,\nbenefiting from the highly confined geometry in addition to the ENZ enhancement\neffect. These ENZ NCs may offer a scalable and printable material solution for\ndynamic photonic and optoelectronic devices."
    },
    {
        "anchor": "Velocity selection problem for combined motion of melting and\n  solidification fronts: We discuss a free boundary problem for two moving solid-liquid interfaces\nthat strongly interact via the diffusion field in the liquid layer between\nthem. This problem arises in the context of liquid film migration (LFM) during\nthe partial melting of solid alloys. In the LFM mechanism the system chooses a\nmore efficient kinetic path which is controlled by diffusion in the liquid\nfilm, whereas the process with only one melting front would be controlled by\nthe very slow diffusion in the mother solid phase. The relatively weak\ncoherency strain energy is the effective driving force for LFM. As in the\nclassical dendritic growth problems, also in this case an exact family of\nsteady-state solutions with two parabolic fronts and an arbitrary velocity\nexists if capillary effects are neglected. We develop a velocity selection\ntheory for this problem, including anisotropic surface tension effects. The\nstrong diffusion interaction and coherency strain effects in the solid near the\nmelting front lead to substantial changes compared to classical dendritic\ngrowth.",
        "positive": "Mn$^{2+}$/Mn$^{3+}$ state of La$_{0.7}$Ce$_{0.3}$MnO$_3$ by oxygen\n  reduction and photodoping: Films of cerium-doped LaMnO$_3$, which has been intensively discussed as an\nelectron-doped counterpart to hole-doped mixed-valence lanthanum manganites\nduring the past decade, were analyzed by x-ray photoemission spectroscopy with\nrespect to their manganese valence under photoexcitation. The comparative\nanalysis of the Mn 3s exchange splitting of La$_{0.7}$Ce$_{0.3}$MnO$_3$ (LCeMO)\nfilms in the dark and under illumination clearly shows that both oxygen\nreduction and illumination are able to decrease the Mn valence towards a mixed\n2$+$/3$+$ state, independently of the film thickness and the degree of CeO$_2$\nsegregation. Charge injection from the photoconductive SrTiO$_3$ substrate into\nthe Mn e$_g$ band with carrier lifetimes in the range of tens of seconds and\nintrinsic generation of electron-hole pairs within the films are discussed as\ntwo possible sources of the Mn valence shift and the subsequent electron\ndoping."
    },
    {
        "anchor": "Automated calculations of exchange magnetostriction: We present a methodology based on deformations of the unit cell that allows\nto compute the isotropic magnetoelastic constants, isotropic magnetostrictive\ncoefficients and spontaneous volume magnetostriction associated to the exchange\nmagnetostriction. This method is implemented in the python package MAELAS\n(v3.0), so that it can be used to obtain these quantities by first-principles\ncalculations and classical spin-lattice models in an automated way. We show\nthat the required reference state to obtain the spontaneous volume\nmagnetostriction combines the equilibrium volume of the paramagnetic state and\nmagnetic order of the ground state. We identify an error in the theoretical\nexpression of the isotropic magnetostrictive coefficient $\\lambda^{\\alpha 1,0}$\nfor uniaxial crystals given in previous publications, which is corrected in\nthis work. The presented computational tool may be helpful to provide a better\nunderstanding and characterization of the relationship between the exchange\ninteraction and magnetoelasticity.",
        "positive": "Fluorescence blinking statistics from single CdSe nanorods: We report fluorescence blinking statistics measured from single CdSe nanorods\n(NRs) of seven different sizes with aspect ratio ranging from 3 to 11. This\nstudy included core/shell CdSe/ZnSe NRs and core NRs with two different surface\nligands producing different degrees of surface passivation. We compare the\nfindings for NRs to our measurements of blinking statistics from spherical CdSe\ncore and CdSe/ZnS core/shell nanocrystals (NCs). We find that for both NRs and\nspherical NCs, the off-time probability distributions are well described by a\npower law, while the on-time probability distributions are best described by a\ntruncated power law. The measured crossover time is indistinguishable within\nexperimental uncertainty for core and core/shell NRs, and for core NRs with\ndifferent ligands, indicating that surface passivation does not affect the\nblinking statistics significantly. We find that at fixed excitation intensity,\nthe inverse crossover time increases approximately linearly with increasing NR\naspect ratio; for a given sample, the inverse crossover time increases very\ngradually with increasing excitation intensity. The measured per-particle\nabsorption cross section for all samples indicates that the change in NR\nabsorption cross-section with sample size can account for some but not all of\nthe differences in crossover time. This suggests that the degree of quantum\nconfinement may be partially responsible for the aspect ratio dependence of the\ncrossover time."
    },
    {
        "anchor": "Structure, elastic moduli and thermodynamics of sodium and potassium at\n  ultra-high pressures: The equations of state at room temperature as well as the energies of crystal\nstructures up to pressures exceeding 100 GPa are calculated for Na and K . It\nis shown that the allowance for generalized gradient corrections (GGA) in the\ndensity functional method provides a precision description of the equation of\nstate for Na, which can be used for the calibration of pressure scale. It is\nestablished that the close-packed structures and BCC structure are not\nenergetically advantageous at high enough compressions. Sharply non-monotonous\npressure dependences of elastic moduli for Na and K are predicted and melting\ntemperatures at high pressures are estimated from various melting criteria. The\nphase diagram of K is calculated and found to be in good agreement with\nexperiment.",
        "positive": "Twistronics of Janus transition metal dichalcogenide bilayers: Twisted multilayers of two-dimensional (2D) materials are an increasingly\nimportant platform for investigating quantum phases of matter, and in\nparticular, strongly correlated electrons. The moir\\'e pattern introduced by\nthe relative twist between layers creates effective potentials of\nlong-wavelength, leading to electron localization. However, in contrast to the\nabundance of 2D materials, few twisted heterostructures have been studied until\nnow. Here we develop a first-principle continuum theory to study the electronic\nbands introduced by moire patterns of twisted Janus transition metal\ndichalcogenides (TMD) homo- and hetero-bilayers. The model includes lattice\nrelaxation, stacking-dependent effective mass, and Rashba spin-orbit coupling.\nWe then perform a high-throughput generation and characterization of\nDFT-extracted continuum models for more than a hundred possible combinations of\nmaterials and stackings. Our model predicts that the moir\\'e physics and\nemergent symmetries depend on chemical composition, vertical layer orientation,\nand twist angle, so that the minibands wavefunctions can form triangular,\nhoneycomb, and Kagome networks. Rashba spin-orbit effects, peculiar of these\nsystems, can dominate the moir\\'e bandwidth at small angles. Our work enables\nthe detailed investigation of Janus twisted heterostructures, allowing the\ndiscovery and control of novel electronic phenomena."
    },
    {
        "anchor": "Heterogeneous nucleation on a completely wettable substrate: It is widely believed that heterogeneous nucleation occurs without an\nactivation process when the surface is completely wettable. In this report, we\nreview our previous work [J.Chem.Phys {\\bf 134}, 234709 (2011)] to show that\nthe critical nucleus (droplet) can exist and the activation process may be\nobservable. In fact, a critical nucleus and a free energy barrier always exist\nif the surface potential or the disjoining pressure allows for the first-order\npre-wetting transition on a completely wettable substrate where the contact\nangle is zero. Furthermore, the critical nucleus changes character from the\ncritical nucleus of surface phase transition below bulk coexistence\n(undersaturation) to the critical nucleus of bulk heterogeneous nucleation\nabove the coexistence (oversaturation) when it crosses the coexistence. In this\npaper the morphology and work of formation of a critical nucleus on a\ncompletely-wettable substrate are re-examined to point out the possibility of\nobserving a critical droplet on a completely wettable substrate.",
        "positive": "Phonon and electronic structures and resistance of layered electride\n  Ca2N: DFT calculations: The phonon and electronic properties, the Eliashberg function and the\ntemperature dependence of resistance of electride Ca2N are investigated by the\nDFT-LDA plane-wave method. The phonon dispersion, the partial phonon density of\nstates and the atomic eigenvectors of zero-center phonons are studied. The\nelectronic band dispersion and partial density of states conclude that Ca2N is\na metal and the Ca 3p, 4s and N 2p orbitals are hybridized. For the analysis of\nan electron - phonon interaction (EPI) and its contribution to resistance the\nEliashberg function was calculated and a temperature dependence of resistance\ncaused EPI was found. The present results are in good agreement with experiment\ndata."
    },
    {
        "anchor": "Electronic structure and spectroscopy of the quaternary Heusler alloy\n  Co$_2$Cr$_{1-x}$Fe$_{x}$Al: Quaternary Heusler alloys Co$_2$Cr$_{1-x}$Fe$_{x}$Al with varying Cr to Fe\nratio $x$ were investigated experimentally and theoretically. The electronic\nstructure and spectroscopic properties were calculated using the full\nrelativistic Korringa-Kohn-Rostocker method with coherent potential\napproximation to account for the random distribution of Cr and Fe atoms as well\nas random disorder. Magnetic effects are included by the use of spin dependent\npotentials in the local spin density approximation.\n  Magnetic circular dichroism in X-ray absorption was measured at the $L_{2,3}$\nedges of Co, Fe, and Cr of the pure compounds and the $x=0.4$ alloy in order to\ndetermine element specific magnetic moments. Calculations and measurements show\nan increase of the magnetic moments with increasing iron content. Resonant\n(560eV - 800eV) soft X-ray as well as high resolution - high energy ($\\geq\n3.5$keV) hard X-ray photo emission was used to probe the density of the\noccupied states in Co$_2$Cr$_{0.6}$Fe$_{0.4}$Al.",
        "positive": "Fatigue and retention in the growth window of ferroelectric Hf0.5Zr0.5O2\n  thin films: The growth window of epitaxial Hf0.5Zr0.5O2 is established taking into\naccount the main ferroelectric properties that films have to present\nsimultaneously: high remanent polarization, low fatigue and long retention.\nDefects in the film and imprint field depend on deposition temperature and\noxygen pressure, with an impact on fatigue and retention, respectively. Fatigue\nincreases with substrate temperature and pressure, and retention is short if\nlow temperature is used. The growth window of epitaxial stabilization of\nferroelectric Hf0.5Zr0.5O2 is narrower when all major ferroelectric properties\n(remanence, endurance and retention) are considered, but deposition temperature\nand pressure ranges are still sufficiently wide."
    },
    {
        "anchor": "Mechanism and Scalability in Resistive Switching of Metal-Pr0.7Ca0.3MnO3\n  Interface: The polarity-dependent resistive-switching across metal-Pr0.7Ca0.3MnO3\ninterfaces is investigated. The data suggest that shallow defects in the\ninterface dominate the switching. Their density and fluctuation, therefore,\nwill ultimately limit the device size. While the defects generated/annihilated\nby the pulses and the associated carrier depletion seem to play the major role\nat lower defect density, the defect correlations and their associated hopping\nranges appear to dominate at higher defect density. Therefore, the switching\ncharacteristics, especially the size-scalability, may be altered through\ninterface treatments.",
        "positive": "Topological phonons in an inhomogeneously strained silicon-6: Possible\n  evidence of the high temperature spin superfluidity and the second sound of\n  topological phonons: The superposition of topological phonons and flexoelectronic charge\nseparation in an inhomogeneously strain Si give rise to topological electronic\nmagnetism of phonons. The topological electronic magnetism of phonons is also\nexpected to give rise to stationary spin current or spin superfluidity. In this\nexperimental study, we present possible evidence of spin superfluidity in an\ninhomogeneously strained p-Si thin films samples. The spin superfluidity is\nuncovered using non-local resistance measurement. A resonance behavior is\nobserved in a non-local resistance measurement at 10 kHz and between 270 K and\n281.55 K, which is attributed to the second sound. The observation of second\nsound and spatially varying non-local resistance phase are the evidences for\nspin superfluidity. The spatially varying non-local resistance with opposite\nphase are also observed in Pt/MgO/p-Si sample. The overall non-local responses\ncan be treated as a standing waveform from temporal magnetic moments of the\ntopological phonons."
    },
    {
        "anchor": "NMR relaxation and rattling phonons in type-I Ba8Ga16Sn30 clathrate: Atomic motion of guest atoms inside semiconducting clathrate cages is\nconsidered as an important source for the glasslike thermal behavior.69Ga and\n71Ga Nuclear Magnetic Resonance (NMR) studies on type-I Ba8Ga16Sn30 show a\nclear low temperature relaxation peak attributed to the influence of Ba\nrattling dynamics on the framework-atom resonance, with a quadrupolar\nrelaxation mechanism as the leading contribution. The data are analyzed using a\ntwo-phonon Raman process, according to a recent theory involving localized\nanharmonic oscillators. Excellent agreement is obtained using this model, with\nthe parameters corresponding to a uniform array of localized oscillators with\nvery large anharmonicity.",
        "positive": "Electronic properties of MoSe$_2$ nanowrinkles: Mechanical deformations, either spontaneously occurring during sample\npreparation or purposely induced in their nanoscale manipulation, drastically\naffect the electronic and optical properties of transition metal dichalcogenide\nmonolayers. In this first-principles work based on density-functional theory,\nwe shed light on the interplay among strain, curvature, and electronic\nstructure of MoSe$_2$ nanowrinkles. We analyze their structural properties\nhighlighting the effects of coexisting local domains of tensile and compressive\nstrain in the same system. By contrasting the band structures of the\nnanowrinkles against counterparts obtained for flat monolayers subject to the\nsame amount of strain, we clarify that the specific features of the former,\nsuch as the moderate variation of the band-gap size and its persisting direct\nnature, are ruled by curvature rather than strain. The analysis of the\nwave-function distribution indicates strain-dependent localization of the\nfrontier states in the conduction region while in the valence the sensitivity\nto strain is much less pronounced. The discussion about transport properties,\nbased on the inspection of the effective masses, reveals excellent perspectives\nfor these systems as active components for (opto)electronic devices."
    },
    {
        "anchor": "Alloy Informatics through Ab Initio Charge Density Profiles: Case Study\n  of Hydrogen Effects in Face-Centered Cubic Crystals: Materials design has traditionally evolved through trial-error approaches,\nmainly due to the non-local relationship between microstructures and properties\nsuch as strength and toughness. We propose 'alloy informatics' as a machine\nlearning based prototype predictive approach for alloys and compounds, using\nelectron charge density profiles derived from first-principle calculations. We\ndemonstrate this framework in the case of hydrogen interstitials in\nface-centered cubic crystals, showing that their differential electron charge\ndensity profiles capture crystal properties and defect-crystal interaction\nproperties. Radial Distribution Functions (RDFs) of defect-induced differential\ncharge density perturbations highlight the resulting screening effect, and,\ntogether with hydrogen Bader charges, strongly correlate to a large set of\natomic properties of the metal species forming the bulk crystal. We observe the\nspontaneous emergence of classes of charge responses while coarse-graining over\ncrystal compositions. Nudge-Elastic-Band calculations show that RDFs and charge\nfeatures also connect to hydrogen migration energy barriers between\ninterstitial sites. Unsupervised machine-learning on RDFs supports\nclassification, unveiling compositional and configurational non-localities in\nthe similarities of the perturbed densities. Electron charge density\nperturbations may be considered as bias-free descriptors for a large variety of\ndefects.",
        "positive": "Thermal transport in a 2D amorphous material: Two-dimensional (2D) crystals proved revolutionary soon after graphene was\ndiscovered in 2004. However, 2D amorphous materials only became accessible in\n2020 and remain largely unexplored. In particular, the thermophysical\nproperties of amorphous materials are of great interest upon transition from 3D\nto 2D. Here, we probe thermal transport in 2D amorphous carbon. A cross-plane\nthermal conductivity ($\\kappa$) down to 0.079 $\\rm{Wm}^{-1}K^{-1}$ is measured\nfor van der Waals stacked multilayers at room temperature, which is among the\nlowest reported to date. Meanwhile, an unexpectedly high in-plane $\\kappa$ is\nobtained for freestanding monolayers which is a few times larger than what is\npredicted by conventional wisdom for 3D amorphous carbon with similar\n$\\rm{sp}^{2}$ fraction. Our molecular dynamics simulations reveal the role of\ndisorder and highlight the impact of dimensionality. Amorphous materials at the\n2D limit open up new avenues for understanding and manipulating heat at the\natomic scale."
    },
    {
        "anchor": "The effect of hydrogen on the multiscale mechanical behaviour of a\n  La(Fe,Mn,Si)13-based magnetocaloric material: Magnetocaloric cooling offers the potential to improve the efficiency of\nrefrigeration devices and hence cut the significant CO2 emissions associated\nwith cooling processes. A critical issue in deployment of this technology is\nthe mechanical degradation of the magnetocaloric material during processing and\noperation, leading to limited service-life. The mechanical properties of\nhydrogenated La(Fe,Mn,Si)13-based magnetocaloric material are studied using\nmacroscale bending tests of polycrystalline specimens and in situ micropillar\ncompression tests of single crystal specimens. The impact of hydrogenation on\nthe mechanical properties are quantified. Understanding of the\ndeformation/failure mechanisms is aided by characterization with transmission\nelectron microscopy and atom probe tomography to reveal the arrangement of\nhydrogen atoms in the crystal lattice. Results indicate that the intrinsic\nstrength of this material is ~3-6 GPa and is dependent on the crystal\norientation. Single crystals under compressive load exhibit shearing along\nspecific crystallographic planes. Hydrogen deteriorates the strength of\nLa(Fe,Mn,Si)13 through promotion of transgranular fracture. The weakening\neffect of hydrogen on single crystals is anisotropic; it is significant upon\nshearing parallel to the {111} crystallographic planes but is negligible when\nthe shear plane is {001}-oriented. APT analysis suggests that this is\nassociated with the close arrangement of hydrogen atoms on {222} planes.",
        "positive": "Excited States Calculated by Means of the Linear Muffin-Tin Orbital\n  Method: The most popular electronic structure method, the linear muffin-tin orbital\nmethod (LMTO), in its full-potential (FP) and relativistic forms has been\nextended to calculate the spectroscopic properties of materials form first\nprinciples, i.e, optical spectra, x-ray magnetic circular dichroism (XMCD) and\nmagneto-optical kerr effect (MOKE). The paper describes an overview of the\nFP-LMTO basis set and the calculation of the momentum matrix elements. Some\napplications concerning the computation of optical properties of semiconductors\nand XMCD spectra of transition metal alloys are reviewed."
    },
    {
        "anchor": "Unusual nanostructures of \"lattice matched\" InP on AlInAs: We show that the morphology of the initial monolayers of InP on\nAl0.48In0.52As grown by metalorganic vapor-phase epitaxy does not follow the\nexpected layer-by-layer growth mode of lattice-matched systems, but instead\ndevelops a number of low-dimensional structures, e.g., quantum dots and wires.\nWe discuss how the macroscopically strain-free heteroepitaxy might be strongly\naffected by local phase separation/alloying-induced strain and that the\npreferred aggregation of adatom species on the substrate surface and reduced\nwettability of InP on AlInAs surfaces might be the cause of the unusual (step)\norganization and morphology",
        "positive": "Ising instability of a Holstein phonon mode in graphene: We study the thermal distribution of phonons in a graphene sheet. Due to the\ntwo electronic bands there are two out-of-plane phonon modes with respect to\nthe two sublattices. One of these modes undergoes an Ising transition by\nspontaneously breaking the sublattice symmetry. We calculate the critical\npoint, the renormalization of the phonon frequency and the average lattice\ndistortion. This transition might be observable in Raman scattering and in\ntransport properties."
    },
    {
        "anchor": "Studies on proximity effect in Mo/Bi1.95Sb0.05Se3 hybrid structure: Proximity effect in a mechanically exfoliated Bi1.95Sb0.05Se3 topological\ninsulator (TI) single crystal partially covered with disordered superconducting\n(SC) Mo thin film is reported. Magnetotransport measurement was performed\nsimultaneously across three different regions of the sample viz. SC, TI and\nSC/TI junction. Resistance measured across SC shows a TC at 4.3 K concomitantly\nthe resistance measurement on TI showed a metallic trend with a steep upturn at\nTC. Magneto-resistance (MR) measurement on TI exhibit a positive MR with\nShubnikov-de Haas (SdH) oscillations, whereas on SC a positive MR superimposed\nwith steep cusp close to TC is observed. Across SC/TI junction both SdH\noscillation and the cusp were observed. The frequency of SdH oscillation on\nSC/TI junction is found to be lesser (~ 125 T) as compared to a reference\nBi1.95Sb0.05Se3sample (~ 174 T). Upper critical field HC2 deduced from WHH fit\nwas found to be 17.14 T for a reference Mo film whereas Mo film deposited on TI\nshowed a decreased HC2 of 4.05 T. The coherence length for the former was found\nto be 4.38 nm and for the latter 9.01 nm. The interaction between the spin-less\nCooper pairs in SC with the spin-momentum locked carriers on the surface of TI\nis believed to cause such changes in transport properties.",
        "positive": "How hole defects modify vortex dynamics in ferromagnetic nanodisks: Defects introduced in ferromagnetic nanodisks may deeply affect the structure\nand dynamics of stable vortex-like magnetization. Here, analytical techniques\nare used for studying, among other dynamical aspects, how a small cylindrical\ncavity modify the oscillatory modes of the vortex. For instance, we have\nrealized that if the vortex is nucleated out from the hole its gyrotropic\nfrequencies are shifted below. Modifications become even more pronounced when\nthe vortex core is partially or completely captured by the hole. In these\ncases, the gyrovector can be partially or completely suppressed, so that the\nassociated frequencies increase considerably, say, from some times to several\npowers. Possible relevance of our results for understanding other aspects of\nvortex dynamics in the presence of cavities and/or structural defects are also\ndiscussed."
    },
    {
        "anchor": "Will NIF Work: It is vital that new clean and abundant sources of energy be developed for\nthe sustainability of modern society. Nuclear fusion of the hydrogen isotopes\ndeuterium and tritium, if successful, might make a major contribution toward\nsatisfying this need. The U.S. has an important effort aimed at achieving\npractical inertial confinement fusion, ICF, which has been under development\nfor decades at the Lawrence Livermore National Laboratory. The National\nIgnition Facility (NIF) is a giant laser to multiply-shock and thus\nquasi-isentropically compress a capsule of deuterium-tritium (DT) to high\ndensity and temperature, where the fusion rate is proportional to density\nsquared times temperature to the fourth power. The principal problem that must\nbe solved for NIF to work successfully is elimination of the Rayleigh-Tailor\n(R-T) instability that originates from the interface between the solid shell\nand the DT fuel within it. The R-T instability poisons the fusion reaction by\nreducing the temperature of the DT achieved by dynamic compression driven by\nthe NIF laser. The primary technological problem today is one of Condensed\nMatter and Materials Physics (CMMP), rather than laser technology and plasma\nphysics. The CMMP of the fuel capsule that must be done to minimize growth of\nthe R-T instability is yet to be done. Based on what is known today, it is\nunlikely that NIF will produce practical amounts of fusion energy.",
        "positive": "Deciphering Cryptic Behavior in Bimetallic Transition Metal Complexes\n  with Machine Learning: The rational tailoring of transition metal complexes is necessary to address\noutstanding challenges in energy utilization and storage. Heterobimetallic\ntransition metal complexes that exhibit metal-metal bonding in stacked \"double\ndecker\" ligand structures are an emerging, attractive platform for catalysis,\nbut their properties are challenging to predict prior to laborious synthetic\nefforts. We demonstrate an alternative, data-driven approach to uncovering\nstructure-property relationships for rational bimetallic complex design. We\ntailor graph-based representations of the metal-local environment for these\nheterobimetallic complexes for use in training of multiple linear regression\nand kernel ridge regression (KRR) models. Focusing on oxidation potentials, we\nobtain a set of 28 experimentally characterized complexes to develop a multiple\nlinear regression model. On this training set, we achieve good accuracy (mean\nabsolute error, MAE, of 0.25 V) and preserve transferability to unseen\nexperimental data with a new ligand structure. We trained a KRR model on a\nsubset of 330 structurally characterized heterobimetallics to predict the\ndegree of metal-metal bonding. This KRR model predicts relative metal-metal\nbond lengths in the test set to within 5%, and analysis of key features reveals\nthe fundamental atomic contributions (e.g., the valence electron configuration)\nthat most strongly influence the behavior of complexes. Our work provides\nguidance for rational bimetallic design, suggesting that properties including\nthe formal shortness ratio should be transferable from one period to another."
    },
    {
        "anchor": "Probing the local electronic structure of isovalent Bi atoms in InP: Cross-sectional scanning tunneling microscopy (X-STM) is used to\nexperimentally study the influence of isovalent Bi atoms on the electronic\nstructure of InP. We map the spatial pattern of the Bi impurity state, which\noriginates from Bi atoms down to the sixth layer below the surface, in\ntopographic, filled state X-STM images on the natural $\\{110\\}$ cleavage\nplanes. The Bi impurity state has a highly anisotropic bowtie-like structure\nand extends over several lattice sites. These Bi-induced charge redistributions\nextend along the $\\left\\langle 110\\right\\rangle$ directions, which define the\nbowtie-like structures we observe. Local tight-binding calculations reproduce\nthe experimentally observed spatial structure of the Bi impurity state. In\naddition, the influence of the Bi atoms on the electronic structure is\ninvestigated in scanning tunneling spectroscopy measurements. These\nmeasurements show that Bi induces a resonant state in the valence band, which\nshifts the band edge towards higher energies. This is in good agreement to\nfirst principles calculations. Furthermore, we show that the energetic position\nof the Bi induced resonance and its influence on the onset of the valence band\nedge depend crucially on the position of the Bi atoms relative to the cleavage\nplane.",
        "positive": "Revisiting the statistical estimation of activation parameters in\n  incipient plasticity: Incipient plasticity is typically associated with thermally activated events\nlike the nucleation of dislocations in crystalline solids and the activation of\nshear transformation zones in metallic glasses. A widely employed method of\nestimating the activation parameters of such mechanisms is to analyze the\nstatistical distribution of critical loads obtained through a series of\nrepeated measurements. However, this approach has been observed to produce\nactivation volumes of the order of atomic volumes in a variety of materials and\nexperimental setups. Such exceptionally small activation volumes have been\nexplained by conjecturing non-trivial nucleation mechanisms. Here, we\ncritically analyze the inherent assumptions of the statistical method and show\nthat the exceptionally small activation volumes can be a misleading result\nemerging simply from the small statistical variance of activation parameters.\nTo this end, we perform deformation simulations of iron nanopillars under\ntensile and compressive loading and measure the resulting yield stresses.\nAlthough the conventional statistical analysis exhibits extremely small\nactivation volumes, the atomistic simulations indicate a transition pathway\nthat is physically incommensurate with the statistical result. Using a simple\nMonte Carlo scheme and analytical model, we show that even a relatively small\ndispersion in activation parameters can suppress the measured activation volume\nto a significant extent. It suggests that the ultra-small atomic volumes\nreported in the earlier studies do not need exotic mechanisms but can be\nexplained as the misleading outcome obtained by ignoring the physically\nplausible dispersion of activation parameters."
    },
    {
        "anchor": "Laser Induced Magnetization Reversal for Detection in Optical\n  Interconnects: Optical interconnect has emerged as the front-runner to replace electrical\ninterconnect especially for off-chip communication. However, a major drawback\nwith optical interconnects is the need for photodetectors and amplifiers at the\nreceiver, implemented usually by direct bandgap semiconductors and analog CMOS\ncircuits, leading to large energy consumption and slow operating time. In this\narticle, we propose a new optical interconnect architecture that uses a\nmagnetic tunnel junction (MTJ) at the receiver side that is switched by\nfemtosecond laser pulses. The state of the MTJ can be sensed using simple\ndigital CMOS latches, resulting in significant improvement in energy\nconsumption. Moreover, magnetization in the MTJ can be switched on the\npicoseconds time-scale and our design can operate at a speed of 5 Gbits/sec for\na single link.",
        "positive": "Concepts of Ferrovalley Material and Anomalous Valley Hall Effect: Valleytronics rooted in the valley degree of freedom is of both theoretical\nand technological importance as it offers additional opportunities for\ninformation storage and electronic, magnetic and optical switches. In analogy\nto ferroelectric materials with spontaneous charge polarization in electronics,\nas well as ferromagnetic materials with spontaneous spin polarization in\nspintronics, here we introduce a new member of ferroic-family, i.e. a\nferrovalley material with spontaneous valley polarization. Combining a two-band\nkp model with first-principles calculations, we show that 2H-VSe2 monolayer,\nwhere the spin-orbit coupling coexists with the intrinsic exchange interaction\nof transition-metal-d electrons, is such a room-temperature ferrovalley\nmaterial. We further predict that such system could demonstrate many\ndistinctive properties, for example, chirality-dependent optical band gap and\nmore interestingly, anomalous valley Hall effect. On account of the latter, a\nseries of functional devices based on ferrovalley materials, such as\nvalley-based nonvolatile random access memory, valley filter, are contemplated\nfor valleytronic applications."
    },
    {
        "anchor": "Anisotropic work function of elemental crystals: The work function is a fundamental electronic property of a solid that varies\nwith the facets of a crystalline surface. It is a crucial parameter in\nspectroscopy as well as materials design, especially for technologies such as\nthermionic electron guns and Schottky barriers. In this work, we present the\nlargest database of calculated work functions for elemental crystals to date.\nThis database contains the anisotropic work functions of more than 100\npolymorphs of about 72 elements and up to a maximum Miller index of two and\nthree for non-cubic and cubic crystals, respectively. The database has been\nrigorously validated against previous experimental and computational data where\navailable. We also propose a weighted work function based on the Wulff shape\nthat can be compared to measurements from polycrystalline specimens, and show\nthat this weighted work function can be modeled empirically using simple atomic\nparameters. Furthermore, for the first time, we were able to analyze simple\nbond breaking rules for metallic systems beyond a maximum Miller index of one,\nallowing for a more generalized investigation of work function anisotropy.",
        "positive": "3D characterization of ultrasonic melt processing on the microstructural\n  refinement of Al-Cu alloys by synchrotron X-ray tomography: The effect of ultrasonic melting processing on three-dimensional architecture\nof intermetallic phases and pores in two multicomponent cast Al-5.0Cu-0.6Mn-0.5\nFe alloys is characterized using conventional microscopy and synchrotron X-ray\nmicrotomography. The two alloys are found to contain intermetallic phases such\nas Al15(FeMn)3Cu2, Al7Cu2Fe, Al3(FeMn), Al6(FeMn), and Al2Cu that have complex\nnetworked morphology in 3D. The application of USP in alloys can obtained\nrefined and equiaxed microstructures. The grain size of 0.5Fe and 1.0 Fe alloys\nis greatly decreased from 16.9 m, 15.8 m without USP to 13.3 m, 12.2 m with\nUSP, respectively. The results show that USP significantly reduce the volume\nfraction, grain size, interconnectivity, and equivalent diameter of the\nintermetallic phases in both alloys. The volume fraction of pores in both\nalloys is reduced due to the USP degassing effect. The refinement mechanism of\nUSP induced fragmentation of primary and secondary dendrites via acoustic\nbubbles and acoustic streaming flow were discussed."
    },
    {
        "anchor": "Charge transfer and interfacial magnetism in (LaNiO3)n/(LaMnO3)2\n  superlattices: (LaNiO3)n/(LaMnO3)2 superlattices were grown using ozone-assisted molecular\nbeam epitaxy, where LaNiO3 is a paramagnetic metal and LaMnO3 is an\nantiferromagnetic insulator. The superlattices exhibit excellent crystallinity\nand interfacial roughness of less than 1 unit cell. X-ray spectroscopy and\ndichroism measurements indicate that electrons are transferred from the LaMnO3\nto the LaNiO3, inducing magnetism in LaNiO3. Magnetotransport measurements\nreveal a transition from metallic to insulating behavior as the LaNiO3 layer\nthickness is reduced from 5 unit cells to 2 unit cells and suggest a modulated\nmagnetic structure within LaNiO3.",
        "positive": "Direct observation of anapoles by neutron diffraction: The scope of magnetic neutron scattering has been expanded by the observation\nof electronic Dirac dipoles (anapoles) that are polar (parity-odd) and magnetic\n(time-odd). A zero-magnetization ferromagnet Sm0.976Gd0.024Al2 with a\ndiamond-type structure presents Dirac multipoles at basis-forbidden reflections\nthat include the standard (2, 2, 2) reflection. Magnetic amplitudes measured at\nfour such reflections are in full accord with a structure factor calculated\nfrom the appropriate magnetic space group."
    },
    {
        "anchor": "Tunable photostriction of halide perovskites through energy dependent\n  photoexcitation: Halide perovskites exhibit giant photostriction, that is, volume or shape\nchanges upon illumination. However, the microscopic origin of this phenomenon\nremains unclear and there are experimental reports of both light-induced\nlattice expansion and contraction. In this paper we establish a general method,\nbased on first-principles calculations and molecular orbital theory, which\nprovides a microscopic picture of photostriction in insulators based on the\norbital characters of their electronic bands near the Fermi level. For\nlead-halide perovskites, we find that different valence states have different\nbonding characters, leading to opposing strengthening or weakening of bonds\ndepending on the photoexcitation energy. The overall trend is that light\ninduces lattice contraction at low excitation energies, while giant lattice\nexpansion occurs at high excitation energies, rationalizing experimental\nreports.",
        "positive": "Self-similarity and scaling of thermal shock fractures: The problem of crack pattern formation due to thermal shock loading at the\nsurface of half-space is solved numerically using two-dimensional boundary\nelement method. The results of numerical simulations with 100-200 random\nsimultaneously growing and interacting cracks are used to obtain scaling\nrelations for crack length and spacing. The numerical results predict that such\nprocess of pattern formation with quasi-static crack growth is not stable and\nat some point the excess energy leads to unstable propagation of one of the\nlongest crack. The onset of instability has also been determined from numerical\nresults."
    },
    {
        "anchor": "Unification of the phonon mode behaviour in semiconductor alloys: Theory\n  and ab initio calculations: We demonstrate how to overcome serious problems in understanding and\nclassification of vibration spectra in semiconductor alloys, following from\ntraditional use of the virtual crystal approximation (VCA). We show that such\ndifferent systems as InGaAs (1-bond->1-mode behavior), InGaP (modified 2-mode)\nand ZnTeSe (2-bond->1-mode) obey in fact the same phonon mode behavior - hence\nprobably a universal one - of a percolation-type (1-bond->2-mode). The change\nof paradigm from the `VCA insight' (an averaged microscopic one) to the\n`percolation insight' (a mesoscopic one) offers a promising link towards the\nunderstanding of alloy disorder. The discussion is supported by ab initio\nsimulation of the phonon density of states at the zone-center of representative\nsupercells at intermediary composition (ZnTeSe) and at the impurity-dilute\nlimits (all systems). In particular, we propose a simple ab initio `protocol'\nto estimate the basic input parameters of our semi-empirical `percolation'\nmodel for the calculation of the 1-bond->2-mode vibration spectra of zincblende\nalloys. With this, the model turns self-sufficient.",
        "positive": "Thermal transport and thermoelectric properties of transition metal\n  dichalcogenides Mo$X_2$ from first-principles calculation: The properties of two-dimensional (2D) materials have been extensively\nstudied and applied in various applications. Our interest is to theoretically\ninvestigate the thermal transport and thermoelectric properties of the 2D\ntransition metal dichalcogenides Mo$X_2$ ($X$ = S, Se, Te). We employ density\nfunctional theory and Boltzmann transport theory with relaxation-time\napproximation to calculate the electronic and transport properties. We also\nimplemented the kinetic-collective model to improve the calculation of lattice\nthermal conductivity. Our calculations indicate that MoTe$_2$ has the highest\nZT of 2.77 among the other Mo$X_2$ at 550 K due to its low thermal conductivity\nand high electrical conductivity. Consequently, we suggest that Mo$X_2$\nmonolayers hold promise as materials for energy conversion devices due to their\nrelatively high ZT. Moreover, these results could be beneficial to design 2D\nmaterial based high performance thermoelectric devices."
    },
    {
        "anchor": "Molecular encapsulation from the liquid phase and graphene nanoribbon\n  growth in carbon nanotubes: Growing graphene nanoribbons from small organic molecules encapsulated in\ncarbon nanotubes can result in products with uniform width and chirality. We\npropose a method based on encapsulation of 1,2,4-trichlorobenzene from the\nliquid phase and subsequent annealing. This procedure results in graphene\nnanoribbons several tens of nanometers long. The presence of nanoribbons was\nproven by Raman spectra both on macroscopic samples and on the nanoscale by\ntip-enhanced Raman scattering and high-resolution transmission electron\nmicroscopic images.",
        "positive": "Structure and phase boundaries of compressed liquid hydrogen: We have mapped the molecular-atomic transition in liquid hydrogen using first\nprinciples molecular dynamics. We predict that a molecular phase with\nshort-range orientational order exists at pressures above 100 GPa. The presence\nof this ordering and the structure emerging near the dissociation transition\nprovide an explanation for the sharpness of the molecular-atomic crossover and\nthe concurrent pressure drop at high pressures. Our findings have non-trivial\nimplications for simulations of hydrogen; previous equation of state data for\nthe molecular liquid may require revision. Arguments for the possibility of a\n$1^{st}$ order liquid-liquid transition are discussed."
    },
    {
        "anchor": "Nanostructured Immunosensors. Application to the detection of\n  Progesterone: A novel nanostructured electrochemical immunsensor for the determination of\nprogesterone is reported. The approach combines the properties of gold\nnanoparticles with the use of a graphite-Teflon composite electrode matrix,\ninto which gold nanoparticles are incorporated by simple physical inclusion.\nThe antibody anti-progesterone was directly attached to the electrode surface.\nThe immunosensor functioning is based on competitive assay between progesterone\nand alkaline phosphatase-labelled progesterone. Monitoring of the affinity\nreaction was accomplished by the electrochemical oxidation of 1-naphtol.\nModification of the graphite -Teflon electrode matrix with gold nanoparticles\nimproves substantially the electrooxidation response of 1-naphtol. Using a\ndetection potential of +0.3V, a detection limit for progesterone of 0.84 ng\nml-1 was obtained. Analysis of seven milk samples spiked at a 3.5 ng ml-1\nprogesterone concentration level yielded a mean recovery of 101+6%. Detection\nof the antigen-antibody reaction with a graphite - Teflon - colloidal - gold -\nTyrosinase electrode, using phenylphosphate as alkaline phosphatase substrate\nto generate phenol, which is subsequently reduced at -0.1 V at the composite\nelectrode, produced a high improvement in the sensitivity for progesterone\ndetection",
        "positive": "Looking for new thermoelectric materials among the TMX intermetallics\n  using high-throughput calculations: Within 4 different crystal structures, 2280 ternary intermetallic\nconfigurations have been investigated via high-throughput density functional\ntheory calculations in order to discover new semiconducting materials. The\nscreening is restricted to intermetallics with the equimolar composition TMX,\nwhere T is a transition metal from the Ti, V, Cr columns, Sr, Ba, Y and La, M\nan element from the first line of transition metals and X a sp elements (Al, P,\nSi, Sn and Sb), i.e. to a list of 24 possible elements. Since the calculations\nare done combinatorically, every possible ternary composition is considered,\neven those not reported in the literature. All these TMX configurations are\ninvestigated in the 4 most reported structure-types: TiNiSi, MgAgAs, BeZrSi and\nZrNiAl. With an excellent agreement between calculations and literature for the\nreported stable phases, we identify 472 possible stable compounds among which\n21 are predicted as non-metallic. Among these 21 compositions, 4 could be\nconsidered as new semiconductors."
    },
    {
        "anchor": "Large scale ab initio calculations based on three levels of\n  parallelization: We suggest and implement a parallelization scheme based on an efficient\nmultiband eigenvalue solver, called the locally optimal block preconditioned\nconjugate gradient LOBPCG method, and using an optimized three-dimensional (3D)\nfast Fourier transform (FFT) in the ab initio}plane-wave code ABINIT. In\naddition to the standard data partitioning over processors corresponding to\ndifferent k-points, we introduce data partitioning with respect to blocks of\nbands as well as spatial partitioning in the Fourier space of coefficients over\nthe plane waves basis set used in ABINIT. This k-points-multiband-FFT\nparallelization avoids any collective communications on the whole set of\nprocessors relying instead on one-dimensional communications only. For a single\nk-point, super-linear scaling is achieved for up to 100 processors due to an\nextensive use of hardware optimized BLAS, LAPACK, and SCALAPACK routines,\nmainly in the LOBPCG routine. We observe good performance up to 200 processors.\nWith 10 k-points our three-way data partitioning results in linear scaling up\nto 1000 processors for a practical system used for testing.",
        "positive": "Spin configurations in Co2FeAl0.4Si0.6 Heusler alloy thin film elements: We determine experimentally the spin structure of half-metallic\nCo2FeAl0.4Si0.6 Heusler alloy elements using magnetic microscopy. Following\nmagnetic saturation, the dominant magnetic states consist of quasi-uniform\nconfigurations, where a strong influence from the magnetocrystalline anisotropy\nis visible. Heating experiments show the stability of the spin configuration of\ndomain walls in confined geometries up to 800 K. The switching temperature for\nthe transition from transverse to vortex walls in ring elements is found to\nincrease with ring width, an effect attributed to structural changes and\nconsequent changes in magnetic anisotropy, which start to occur in the narrower\nelements at lower temperatures."
    },
    {
        "anchor": "Field dependence of magnetization reversal by spin transfer: We analyse the effect of the applied field (Happl) on the current-driven\nmagnetization reversal in pillar-shaped Co/Cu/Co trilayers, where we observe\ntwo different types of transition between the parallel (P) and antiparallel\n(AP) magnetic configurations of the Co layers. If Happl is weaker than a rather\nsmall threshold value, the transitions between P and AP are irreversible and\nrelatively sharp. For Happl exceding the threshold value, the same transitions\nare progressive and reversible. We show that the criteria for the stability of\nthe P and AP states and the experimentally observed behavior can be precisely\naccounted for by introducing the current-induced torque of the spin transfer\nmodels in a Landau-Lifschitz-Gilbert equation. This approach also provides a\ngood description for the field dependence of the critical currents.",
        "positive": "Two-dimensional electron gas formation in undoped\n  In[0.75]Ga[0.25]As/In[0.75]Al[0.25]As quantum wells: We report on the achievement of a two-dimensional electron gas in completely\nundoped In[0.75]Al[0.25]As/In[0.75]Ga[0.25]As metamorphic quantum wells. Using\nthese structures we were able to reduce the carrier density, with respect to\nreported values in similar modulation-doped structures. We found experimentally\nthat the electronic charge in the quantum well is likely due to a deep-level\ndonor state in the In[0.75]Al[0.25]As barrier band gap, whose energy lies\nwithin the In[0.75]Ga[0.25]As/In[0.75]Al[0.25]As conduction band discontinuity.\nThis result is further confirmed through a Poisson-Schroedinger simulation of\nthe two-dimensional electron gas structure."
    },
    {
        "anchor": "Dislocation Core Energies and Core Fields from First Principles: Ab initio calculations in bcc iron show that a <111> screw dislocation\ninduces a short-range dilatation field in addition to the Volterra elastic\nfield. This core field is modeled in anisotropic elastic theory using force\ndipoles. The elastic modeling thus better reproduces the atom displacements\nobserved in ab initio calculations. Including this core field in the\ncomputation of the elastic energy allows deriving a core energy which converges\nfaster with the cell size, thus leading to a result which does not depend on\nthe geometry of the dislocation array used for the simulation.",
        "positive": "First principles evaluation of phase stability in the In-Sn binary\n  system: The In-Sn binary alloy system exhibits several unusual features that\nchallenge crystallographic and thermodynamic expectations. We combine first\nprinciples total energy calculation with simple thermodynamic modeling to\naddress two key points. First, we evaluate energies along the Bain path to\ninterpret the discontinuous transition between the phases $\\alpha$-In (Pearson\ntype tI2) and $\\beta$--In$_3$Sn (also Pearson type tI2) that are identical in\nsymmetry. Second, we demonstrate that the solid solution phases\n$\\beta$-In$_3$Sn and $\\gamma$-InSn$_4$ (Pearson type hP1) exist at high\ntemperatures only, and they exhibit eutectoid decompositions at low\ntemperatures."
    },
    {
        "anchor": "Low temperature thermal expansion of pure and inert gas-doped Fullerite\n  C60: The low temperature (2-24 K) thermal expansion of pure (single crystal and\npolycrystalline) C60 and polycrystalline C60 intercalated with He, Ne, Ar, and\nKr has been investigated using high-resolution capacitance dilatometer. The\ninvestigation of the time dependence of the sample length variations on heating\nshows that the thermal expansion is determined by the sum of positive and\nnegative contributions, which have different relaxation times. The negative\nthermal expansion usually prevails at helium temperatures. The positive\nexpansion is connected with the phonon thermalization of the system. The\nnegative expansion is caused by reorientation of the C60 molecules. It is\nassumed that the reorientation is of quantum character. The inert gas\nimpurities affect very strongly the reorientation of the C60 molecules\nespecially at liquid helium temperatures. A temperature hysteresis of the\nthermal expansion coefficient of Kr- and He- C60 solutions has been revealed.\nThe hysteresis is attributed to orientational polyamorphous transformation in\nthese systems.",
        "positive": "Rapid Surface Oxidation as a Source of Surface Degradation Factor for\n  Bi2Se3: Bi2Se3 is a topological insulator with metallic surface states residing in a\nlarge bulk bandgap. It is believed that Bi2Se3 gets additional n-type doping\nafter exposure to atmosphere, thereby reducing the relative contribution of\nsurface states in total conductivity. In this letter, transport measurements on\nBi2Se3 nanoribbons provide additional evidence of such environmental doping\nprocess. Systematic surface composition analyses by X-ray photoelectron\nspectroscopy reveal fast formation and continuous growth of native oxide on\nBi2Se3 under ambient conditions. In addition to n-type doping at the surface,\nsuch surface oxidation is likely the material origin of the degradation of\ntopological surface states. Appropriate surface passivation or encapsulation\nmay be required to probe topological surface states of Bi2Se3 by transport\nmeasurements."
    },
    {
        "anchor": "Erbium Silicide Growth in the Presence of Residual Oxygen: The chemical changes of Ti/Er/n-Si(100) stacks evaporated in high vacuum and\ngrown ex situ by rapid thermal annealing were scrutinized. The emphasis was\nlaid on the evolution with the annealing temperature of (i) the Er-Si\nsolid-state reaction and (ii) the penetration of oxygen into Ti and its\nsubsequent interaction with Er. For that sake, three categories of specimens\nwere analyzed: as-deposited, annealed at 300{\\deg}C, and annealed at\n600{\\deg}C. It was found that the presence of residual oxygen into the\nannealing atmosphere resulted in a substantial oxidation of the Er film\nsurface, irrespective of the annealing temperature. However, the part of the Er\nfilm in intimate contact with the Si bulk formed a silicide (amorphous at\n300{\\deg}C and crystalline at 600{\\deg}C) invariably free of oxygen, as\ntestified by x-ray photoelectron spectroscopy depth profiling and Schottky\nbarrier height extraction of 0.3 eV at 600{\\deg}C. This proves that, even if Er\nis highly sensitive to oxygen contamination, the formation of low Schottky\nbarrier Er silicide contacts on n-Si is quite robust. Finally, the production\nof stripped oxygen-free Er silicide was demonstrated after process\noptimization.",
        "positive": "Electronic transport in ferromagnetic alloys and the Slater-Pauling\n  Curve: Experimental measurements of the residual resistivity $\\rho(x)$ of the binary\nalloy system Fe$_{1-x}$Cr$_x$ have shown an anomalous concentration dependence\nwhich deviates significantly from Nordheim's rule. In the low ($x < 10%$) Cr\nconcentration regime the resistivity has been found to increase linearly with\n$x$ until $\\approx$ 10% Cr where the resistivity reaches a plateau persisting\nto $\\approx$ 20% Cr. In this paper we present $ab$-$initio$ calculations of\n$\\rho(x)$ which explain this anomalous behavior and which are based on the\nKorringa-Kohn-Rostoker (KKR) method in conjunction with the Kubo-Greenwood\nformalism. Furthermore we are able to show that the effects of short-range\nordering or clustering have little effect via our use of the nonlocal\ncoherent-potential approximation (NL-CPA). For the interpretation of the\nresults we study the alloys' electronic structure by calculating the Bloch\nspectral function particularly in the vicinity of the Fermi energy. From the\nanalysis of our results we infer that a similar behavior of the resistivity\nshould also be obtained for iron-rich Fe$_{1-x}$V$_x$ alloys - an inference\nconfirmed by further explicit resistivity calculations. Both of these alloy\nsystems belong to the same branch of the famous Slater-Pauling plot and we\npostulate that other alloy systems from this branch should show a similar\nbehavior. Our calculations show that the appearance of the plateau in the\nresistivity can be attributed to the dominant contribution of minority spin\nelectrons to the conductivity which is nearly unaffected by increase in Cr/V\nconcentration $x$ and we remark that this minority spin electron feature is\nalso responsible for the simple linear variation of the average moment in the\nSlater-Pauling plot for these materials."
    },
    {
        "anchor": "Large Anomalous Nernst Effect in a Skyrmion Crystal: Thermoelectric properties of a model Skyrmion crystal were theoretically\ninvestigated, and it was found that its large anomalous Hall conductivity,\ncorresponding to large Chern numbers induced by its peculiar spin structure\nleads to a large transverse thermoelectric voltage through the anomalous Nernst\neffect. This implies the possibility of finding good thermoelectric materials\namong Skyrmion systems, and thus motivates our quests for them by means of the\nfirst-principles calculations as were employed here.",
        "positive": "Advanced materials for magnetic cooling:fundamentals and practical\n  aspects: Over the last two decades, the research activities on magnetocalorics have\nbeen exponentially increased leading to the discovery of a wide category of\nmaterials including intermetallics and oxides. Even though the reported\nmaterials were found to show excellent magnetocaloric properties on laboratory\nscale, only a restricted family among them could be upscaled toward industrial\nlevels and implemented as refrigerants in magnetic cooling devices. On the\nother hand, in the most of reported reviews, the magnetocaloric materials are\nusually discussed in terms of their adiabatic temperature and entropy changes,\nwhich is not enough to get more insight about their large scale applicability.\nIn this review, not only the fundamental properties of recently reported\nmagnetocaloric materials are discussed but also their thermodynamic performance\nin functional devices. The reviewed families particularly include Gd1-xRx\nalloys, LaFe13-xSix, MnFeP1-xAsx and R1-xAxMnO3 based compounds. Other relevant\npractical aspects such as mechanical stability, synthesis and corrosion issues\nare discussed. In addition, the intrinsic and extrinsic parameters that play a\ncrucial role in the control of magnetic and magnetocaloric properties are\nregarded. In order to reproduce the needed magnetocaloric parameters, some\npractical models are proposed. Finally, the concepts of the rotating\nmagnetocaloric effect and multilayered magnetocalorics are introduced."
    },
    {
        "anchor": "Pressure induced novel compounds in the Hf-O system from\n  first-principles calculations: Using first-principles evolutionary simulations, we have systematically\ninvestigated phase stability in the Hf-O system at pressure up to 120 GPa. New\ncompounds Hf5O2, Hf3O2, HfO and HfO3 are discovered to be thermodynamically\nstable at certain pressure ranges and a new stable high-pressure phase is found\nfor Hf2O with space group Pnnm and anti-CaCl2-type structure. Both P62m-HfO and\nP4m2-Hf2O3 show semimetallic character. Pnnm-HfO3 shows interesting structure,\nsimultaneously containing oxide O2- and peroxide [O-O]2- anions. Remarkably, it\nis P62m-HfO rather than OII-HfO2 that exhibits the highest mechanical\ncharacteristics among Hf-O compounds. Pnnm-Hf2O, Imm2-Hf5O2, P31m-Hf2O and\nP4m2-Hf2O3 phases also show superior mechanical properties, these phases can be\nquenched to ambient pressure and their properties can be exploited.",
        "positive": "Partial Charge Transfer and Absence of Induced Magnetization in\n  EuS(111)/Bi$_2$Se$_3$ Heterostructures: Heterostructures made from topological and magnetic insulators promise to\nform excellent platforms for new electronic and spintronic functionalities\nmediated by interfacial effects. We report the results of a first-principles\ndensity functional theory study of the geometric, electronic structure, and\nmagnetic properties of EuS(111)/Bi$_2$Se$_3$ interface, including van der Waals\nand relativistic spin-orbit effects. In contrast to previous theoretical\nstudies, we find no appreciable magnetic anisotropy in such a heterostructure.\nWe also do not see additional induced magnetization at the interface or the\nmagnetic proximity effect on the topological states. This is due to the\nlocalized nature of Eu moments, and because of a partial charge transfer of\n$\\sim$0.5 electron from Eu to Se. The formation of the surface dipole shifts\nthe Dirac cone about 0.4~eV below the chemical potential, and the associated\nelectrostatic screening moves the topological state from the first to the\nsecond quintuple layer of Bi$_2$Se$_3$."
    },
    {
        "anchor": "Evolution of Co/Cu multilayer conductivity during growth: ab intio study: We present ab-initio calculations for the in plane conductivity of Co/Cu\nmultilayer slabs. The electronic structure of the multilayer slabs is\ncalculated by means of density functional theory within a screened KKR scheme.\nTransport properties are described using the Boltzmann equation in relaxation\ntime approximation. We study the change of the conductivity during growth of\nthe multilayer, and we can reproduce the anomalous, non Ohmic, behavior\nobserved experimentally in several multilayer systems. Our results show that\nthis behavior can be explained in terms of the electronic structure of the slab\nonly. No extra assumption for the scattering at the interfaces is necessary.\nThe connection of electronic structure and conductivity during layer-by-layer\ngrowth is elucidated by analyzing the layer-projected conductivities.",
        "positive": "Grain-boundary grooving and agglomeration of alloy thin films with a\n  slow-diffusing species: We present a general phase-field model for grain-boundary grooving and\nagglomeration of polycrystalline alloy thin films. In particular, we study the\neffects of slow-diffusing species on grooving rate. As the groove grows, the\nslow species becomes concentrated near the groove tip so that further grooving\nis limited by the rate at which it diffuses away from the tip. At early times\nthe dominant diffusion path is along the boundary, while at late times it is\nparallel to the substrate. This change in path strongly affects the\ntime-dependence of grain boundary grooving and increases the time to\nagglomeration. The present model provides a tool for agglomeration-resistant\nthin film alloy design. keywords: phase-field, thermal grooving, diffusion,\nkinetics, metal silicides"
    },
    {
        "anchor": "Incommensurate host-guest structures in compressed elements:\n  Hume-Rothery effects as origin: Discovery of the incommensurate structure in the element Ba under pressure 15\nyears ago was followed by findings of a series of similar structures in other\ncompressed elements. Incommensurately modulated structures of the host-guest\ntype consist of a tetragonal host structure and a guest structure. The guest\nstructure forms chains of atoms embedded in the channels of host atoms so that\nthe axial ratio of these subcells along the c axis is not rational. Two types\nof the host-guest structures have been found so far: with the host cells\ncontaining 8 atoms and 16 atoms; in these both types the guest cells contain 2\natoms. These crystal structures contain a non-integer number of atom in their\nunit cell: tI11* in Bi, Sb, As, Ba, Sr, Sc and tI19* in Na, K, Rb. We consider\nhere a close structural relationship of these host-guest structures with the\nbinary alloy phase Au3Cd5-tI32. This phase is related to the family of the\nHume-Rothery phases that is stabilized by the Fermi sphere - Brillouin zone\ninteraction. From similar considerations for alkali and alkaline-earth elements\na necessary condition for structural stability emerges in which the valence\nelectrons band overlaps with the upper core electrons and the valence electron\ncount increases under compression.",
        "positive": "Evidence of Electron-Hole Imbalance in WTe2 from High-Resolution\n  Angle-Resolved Photoemission Spectroscopy: WTe2 has attracted a great deal of attention because it exhibits extremely\nlarge and nonsaturating magnetoresistance. The underlying origin of such a\ngiant magnetoresistance is still under debate. Utilizing laser-based\nangle-resolved photoemission spectroscopy with high energy and momentum\nresolutions, we reveal the complete electronic structure of WTe2. This makes it\npossible to determine accurately the electron and hole concentrations and their\ntemperature dependence. We find that, with increasing the temperature, the\noverall electron concentration increases while the total hole concentration\ndecreases. It indicates that the electron-hole compensation, if it exists, can\nonly occur in a narrow temperature range, and in most of the temperature range\nthere is an electron-hole imbalance. Our results are not consistent with the\nperfect electron-hole compensation picture that is commonly considered to be\nthe cause of the unusual magnetoresistance in WTe2. We identified a flat band\nnear the Brillouin zone center that is close to the Fermi level and exhibits a\npronounced temperature dependence. Such a flat band can play an important role\nin dictating the transport properties of WTe2. Our results provide new insight\non understanding the origin of the unusual magnetoresistance in WTe2."
    },
    {
        "anchor": "Etching of Cr tips for scanning tunneling microscopy of cleavable oxides: We report a detailed three-step roadmap for the fabrication and\ncharacterization of bulk Cr tips for spin-polarized scanning tunneling\nmicroscopy. Our strategy uniquely circumvents the need for ultra-high vacuum\npreparation of clean surfaces or films. First, we demonstrate the role of\n$ex$-$situ$ electrochemical etch parameters on Cr tip apex geometry, using\nscanning electron micrographs of over 70 etched tips. Second, we describe the\nsuitability of the $in$-$situ$ cleaved surface of the layered antiferromagnet\nLa$_{1.4}$Sr$_{1.6}$Mn$_2$O$_7$ to evaluate the spin characteristics of the Cr\ntip, replacing the UHV-prepared test samples that have been used in prior\nstudies. Third, we outline a statistical algorithm that can effectively\ndelineate closely-spaced or irregular cleaved step edges, to maximize the\naccuracy of step height and spin-polarization measurements.",
        "positive": "Interplay between in-plane and flexural phonons in electronic transport\n  of two-dimensional semiconductors: Out-of-plane vibrations are considered as the dominant factor limiting the\nintrinsic carrier mobility of suspended two-dimensional materials at low\ncarrier concentrations. Anharmonic coupling between in-plane and flexural\nphonon modes is usually excluded from the consideration. Here we present a\ntheory for the electron-phonon scattering, in which the anharmonic coupling\nbetween acoustic phonons is systematically taken into account. Our theory is\napplied to the typical group V two-dimensional semiconductors: hexagonal\nphosphorus, arsenic, and antimony. We find that the role of the flexural modes\nis essentially suppressed by their coupling with in-plane modes. At dopings\nlower than 10$^{12}$ cm$^{-2}$ the mobility reduction does not exceed 30\\%,\nbeing almost independent of the concentration. Our findings suggest that\ncompared to in-plane phonons, flexural phonons are considerably less important\nin the electronic transport of two-dimensional semiconductors, even at low\ncarrier concentrations."
    },
    {
        "anchor": "Step bunching and macrostep formation in 1D atomistic scale model of\n  unstable vicinal crystal growth: We devise a new 1D atomistic scale model of vicinal growth based on Cellular\nAutomaton. In it the step motion is realized by executing the automaton rule\nprescribing how adatoms incorporate into the vicinal crystal. Time increases\nafter each rule execution and then nDS diffusional updates of the adatoms are\nperformed. The increase of nDS switches between the diffusion-limited (DL,\nnDS=1) and kinetics-limited (KL, nDS >> 1) regimes of growth. We study the\nunstable step motion by employing two alternative sources of instability -\nbiased diffusion and infinite inverse Ehrlich-Schwoebel barrier (iiSE). The\nresulting step bunches consist of steps but also of macrosteps since there is\nno step-step repulsion incorporated explicitly into the model. This complex\npattern formation is quantified by studying the time evolution of the bunch\nsize N and macrostep size Nm in order to find the proper parameter combinations\nthat rescale the time and thus to obtain the full time-scaling relations\nincluding the pre-factors. For the case of biased diffusion the time-scaling\nexponent beta of N is 1/2 while for the case of iiSE it is 1/3. In both cases\nthe time-scaling exponent beta_m of Nm is ~3beta/4 in the DL regime and 3beta/5\nin the KL one.",
        "positive": "Hidden Weyl Points in Centrosymmetric Paramagnetic Metals: The transition metal dipnictides TaAs2 , TaSb2 , NbAs2 and NbSb2 have\nrecently sparked interest for exhibiting giant magnetoresistance. While the\nexact nature of magnetoresistance in these materials is still under active\ninvestigation, there are experimental results indicating anisotropic negative\nmagnetoresistance. We study the effect of magnetic field on the band structure\ntopology of these materials by applying a Zeeman splitting. In the absence of\nmagnetic field, we find that the materials are weak topological insulators,\nwhich is in agreement with previous studies. When the magnetic field is\napplied, we find that type-II Weyl points form. This result is found first from\na symmetry argument, and then numerically for a k.p model of TaAs2 and a\ntight-binding model of NbSb2. This effect can be of help in search for an\nexplanation of the anomalous magnetoresistance in these materials."
    },
    {
        "anchor": "Large magnetoresistance in $\u03c0$-conjugated semiconductor thin film\n  devices: Following the recent discovery of large magnetoresistance at room temperature\nin polyfluorence sandwich devices, we have performed a comprehensive\nmagnetoresistance study on a set of organic semiconductor sandwich devices made\nfrom different pi-conjugated polymers and small molecules. The measurements\nwere performed at different temperatures, ranging from 10K to 300K, and at\nmagnetic fields, $B < 100mT$. We observed large negative or positive\nmagnetoresistance (up to 10% at 300K and 10mT) depending on material and device\noperating conditions. We compare the results obtained in devices made from\ndifferent materials with the goal of providing a comprehensive picture of the\nexperimental data. We discuss our results in the framework of known\nmagnetoresistance mechanisms and find that none of the existing models can\nexplain our results.",
        "positive": "MoTe2 as a natural hyperbolic material across the visible and the\n  ultraviolet region: Hyperbolic materials are of particular interest for the next generation of\nphotonic and optoelectronic devices. Since artificial metamaterials are\nintrinsically limited by the size of their nanostructured components, there has\nbeen a hunt for natural hyperbolic materials in the last few years. In a\nfirst-principles work based on density-functional theory and many-body\nperturbation theory, we investigate the fundamental dielectric response of\nMoTe2 in monolayer, bilayer, and bulk form, and find that it is a natural\ntype-II hyperbolic material with low losses between 3 and 6 eV. Going from the\nmonolayer to the bulk, the energy window of hyperbolic dispersion is\nblue-shifted by a few tenths of an eV. We show that excitonic effects and\noptical anisotropy play a major role in the hyperbolic behavior of MoTe2. Our\nresults confirm the potential of layered materials as hyperbolic media for\nopto-electronics, photonics, and nano-imaging applications."
    },
    {
        "anchor": "Phase Field Modeling of Fast Crack Propagation: We present a continuum theory which predicts the steady state propagation of\ncracks. The theory overcomes the usual problem of a finite time cusp\nsingularity of the Grinfeld instability by the inclusion of elastodynamic\neffects which restore selection of the steady state tip radius and velocity. We\ndeveloped a phase field model for elastically induced phase transitions; in the\nlimit of small or vanishing elastic coefficients in the new phase, fracture can\nbe studied. The simulations confirm analytical predictions for fast crack\npropagation.",
        "positive": "Investigation of Ionic and Anomalous Magnetic Behavior in CrSe$_2$ Using\n  $^8$Li $\u03b2$-NMR: We have studied a mosaic of 1T-CrSe$_2$ single crystals using\n$\\beta$-detected nuclear magnetic resonance of $^{8}$Li from 4 to 300 K. We\nidentify two broad resonances that show no evidence of quadrupolar splitting,\nindicating two magnetically distinct environments for the implanted ion. We\nobserve stretched exponential spin lattice relaxation and a corresponding rate\n($1/T_1$) that increases monotonically above 200 K, consistent with the onset\nof ionic diffusion. A pronounced maximum in $1/T_1$ is observed at the low\ntemperature magnetic transition near 20 K. Between these limits, $1/T_1$\ninstead exhibits a broad minimum with a remarkable absence of strong features\nin the vicinity of structural and magnetic transitions between 150 and 200 K.\nTogether, the results suggest $^{8}$Li$^{+}$ site occupation within the van der\nWaals gap between CrSe$_2$ trilayers. Possible origins of the two environments\nare discussed."
    },
    {
        "anchor": "Long Range Magnetic order stabilized by acceptors: Tuning magnetic order in magnetic semiconductors is a long sought goal. A\nproper concentration of acceptors can dramatically suppress local magnetic\norder in favor of the long one. Using Mn and an acceptor codoped LiZnAs as an\nexample, we demonstrate, by first-principles calculation, the emergence of a\nlong-range magnetic order. This intriguing phenomenon can be understood from an\ninterplay between an acceptor-free magnetism and a band coupling magnetism. Our\nobservation thus lays the ground for a precise control of the magnetic order in\nfuture spintronic devices.",
        "positive": "In situ determination of the energy dependence of the high-frequency\n  mobility in polymers: The high-frequency mobility in disordered systems is governed by transport\nproperties on mesoscopic length scales, which makes it a sensitive probe for\nthe amount of local order. Here we present a method to measure the energy\ndependence of the high frequency mobility by combining an electrochemically\ngated transistor with in-situ quasi-optical measurements in the sub-terahertz\ndomain. We apply this method to\npoly([2-methoxy-5-(3',7'-dimethylocyloxy)]-p-phenylene vinylene) (OC_1C_10-PPV)\nand find a mobility at least as high as 0.1 cm^2V^-1s^-1."
    },
    {
        "anchor": "Coexistence of Multifold and Multidimensional Topological Phonons in\n  KMgBO$_{3}$: Topological interpretations of phonons facilitate a new platform for novel\nconcepts in phonon physics. Though there are ubiquitous set of reports on\ntopological electronic excitations, the same for phonons are extremely limited.\nHere, we propose a new candidate material, KMgBO 3 , which showcase the\nco-existence of several multifold and multidimensional topological phonon\nexcitations, which are protected by spatial and non-spatial symmetries. This\nincludes zero dimensional double, triple and quadratic Weyl phonon nodes, one\ndimensional nodal line/loop and two dimensional doubly degenerate nodal surface\nstates. Nodal line/loop emerges from the spin- 12 phonon nodes, while the two\ndimensional doubly degenerate nodal surface arises from a combination of two\nfold screw rotational and time reversal symmetries. Application of strain\nbreaks the C 3 rotational symmetry, which annihilates the spin-1 double Weyl\nnodes, but preserves other topological features. Interestingly, strain helps to\ncreate two extra single Weyl nodes, which in turn preserve the total chirality.\nAlloying also breaks certain symmetries, destroying most of the topological\nphonon features in the present case. Thus, KMgBO 3 is a promising candidate\nwhich hosts various Weyl points, large Fermi arcs with a very clean phonon\nspectra and tunable topological phonon excitations, and hence certainly worth\nfor future theoretical/experimental investigation of topological phononics.",
        "positive": "Comparative study of tight-binding and ab initio electronic structure\n  calculations focused on magnetic anisotropy in ordered CoPt alloy: An empirical multiorbital (spd) tight binding (TB) model including magnetism\nand spin-orbit coupling is applied to calculations of magnetic anisotropy\nenergy (MAE) in CoPt L1_0 structure. A realistic Slater-Koster parametrisation\nfor single-element transition metals is adapted for the ordered binary alloy.\nSpin magnetic moment and density of states are calculated using a\nfull-potential linearized augmented plane-wave (LAPW) ab initio method and our\nTB code with different variants of the interatomic parameters. Detailed mutual\ncomparison of this data allows for determination of a subset of the compound TB\nparameters tuning of which improves the agreement of the TB and LAPW results.\nMAE calculated as a function of band filling using the refined parameters is in\nbroad agreement with ab initio data for all valence states and in quantitative\nagreement with ab initio and experimental data for the natural band filling.\nOur work provides a practical basis for further studies of relativistic\nmagnetotransport anisotropies by means of local Green's function formalism\nwhich is directly compatible with our TB approach."
    },
    {
        "anchor": "Imaging Seebeck drift of excitons and trions in MoSe2 monolayers: Hyperspectral imaging at cryogenic temperatures is used to investigate\nexciton and trion propagation in MoSe$_2$ monolayers encapsulated with\nhexagonal boron nitride (hBN). Under a tightly focused, continuous-wave laser\nexcitation, the spatial distribution of neutral excitons and charged trions\nstrongly differ at high excitation densities. Remarkably, in this regime the\ntrion distribution develops a halo shape, similar to that previously observed\nin WS2 monolayers at room temperature and under pulsed excitation. In contrast,\nthe exciton distribution only presents a moderate broadening without the\nappereance of a halo. Spatially and spectrally resolved luminescence spectra\nreveal the buildup of a significant temperature gradient at high excitation\npower, that is attributed to the energy relaxation of photoinduced hot\ncarriers. We show, via a numerical resolution of the transport equations for\nexcitons and trions, that the halo can be interpreted as thermal drift of\ntrions due to a Seebeck term in the particle current. The model shows that the\ndifference between trion and exciton profiles is simply understood in terms of\nthe very different lifetimes of these two quasiparticles.",
        "positive": "The crystal structure, chemical bonding and magnetic properties of the\n  intercalation compounds Cr$_x$ZrTe$_2$ ($x$ = 0-0.3): New intercalation compounds Cr$_x$ZrTe$_2$ were synthesized in the Cr\nconcentration range of x=0-0.3. A thorough study of the crystal and electronic\nstructure has been performed. It was found that there is competition in the\ndistribution of the Cr atoms over the octa- and tetrahedral sites in the van\nder Waals gap, depending on the Cr content. The ordering of the Cr atoms was\nfound at x = 0.25; at the same time, the lattice symmetry decreases from\ntrigonal P-3m1 to monoclinic F2/m. This ordering stabilizes the octahedral\ncoordination of the Cr atoms by Te atoms. The analysis of the experimental data\non the electronic structure and DOS calculations showed that the Cr 3d states\nare spin-split."
    },
    {
        "anchor": "Bound Magnetic Polaron Interactions in Insulating Doped Diluted Magnetic\n  Semiconductors: The magnetic behavior of insulating doped diluted magnetic semiconductors\n(DMS) is characterized by the interaction of large collective spins known as\nbound magnetic polarons. Experimental measurements of the susceptibility of\nthese materials have suggested that the polaron-polaron interaction is\nferromagnetic, in contrast to the antiferromagnetic carrier-carrier\ninteractions that are characteristic of nonmagnetic semiconductors. To explain\nthis behavior, a model has been developed in which polarons interact via both\nthe standard direct carrier-carrier exchange interaction (due to virtual\ncarrier hopping) and an indirect carrier-ion-carrier exchange interaction (due\nto the interactions of polarons with magnetic ions in an interstitial region).\nUsing a variational procedure, the optimal values of the model parameters were\ndetermined as a function of temperature. At temperatures of interest, the\nparameters describing polaron-polaron interactions were found to be nearly\ntemperature-independent. For reasonable values of these constant parameters, we\nfind that indirect ferromagnetic interactions can dominate the direct\nantiferromagnetic interactions and cause the polarons to align. This result\nsupports the experimental evidence for ferromagnetism in insulating doped DMS.",
        "positive": "Expansive Open Fermi Arcs and Connectivity Changes Induced by Infrared\n  Phonons in ZrTe5: Expansive open Fermi arcs covering most of the surface Brillouin zone (SBZ)\nare desirable for detection and control of many topological phenomena, but so\nfar has been only reported for Kramers-Weyl points, or unconventional chiral\nfermions, pinned at time-reversal invariant momentum in chiral materials. Here\nusing first-principles band structure calculations, we show that for\nconventional Weyl points in ZrTe5 with the chirality of +1/-1 near the BZ\ncenter at general momentum induced by one of the infrared phonons, the second\nlowest B1u mode for breaking inversion symmetry, they can also form expansive\nopen Fermi arcs across the SBZ boundary to occupy most of the SBZ when\nprojected on (001) surface. We reveal that such expansive open Fermi arcs are\nevolved from the topological surface states that connect multiple surface Dirac\npoints on the (001) surface of the topological insulator phases without lattice\ndistortion in ZrTe5. Furthermore, we find that the connectivity of the induced\nopen Fermi arcs can be changed by the magnitude of the lattice distortion of\nthis infrared phonon mode. Thus, we propose that using coherent optical phonon\nto modulate lattice parameters can offer ways to induce novel topological\nfeatures including expansive open Fermi arcs and dynamically control Fermi arcs\nconnectivity in ZrTe5."
    },
    {
        "anchor": "Machine learning based prediction of the electronic structure of\n  quasi-one-dimensional materials under strain: We present a machine learning based model that can predict the electronic\nstructure of quasi-one-dimensional materials while they are subjected to\ndeformation modes such as torsion and extension/compression. The technique\ndescribed here applies to important classes of materials such as nanotubes,\nnanoribbons, nanowires, miscellaneous chiral structures and nano-assemblies,\nfor all of which, tuning the interplay of mechanical deformations and\nelectronic fields is an active area of investigation in the literature. Our\nmodel incorporates global structural symmetries and atomic relaxation effects,\nbenefits from the use of helical coordinates to specify the electronic fields,\nand makes use of a specialized data generation process that solves the\nsymmetry-adapted equations of Kohn-Sham Density Functional Theory in these\ncoordinates. Using armchair single wall carbon nanotubes as a prototypical\nexample, we demonstrate the use of the model to predict the fields associated\nwith the ground state electron density and the nuclear pseudocharges, when\nthree parameters - namely, the radius of the nanotube, its axial stretch, and\nthe twist per unit length - are specified as inputs. Other electronic\nproperties of interest, including the ground state electronic free energy, can\nthen be evaluated with low-overhead post-processing, typically to chemical\naccuracy. We also show how the nuclear coordinates can be reliably determined\nfrom the pseudocharge field using a clustering based technique. Remarkably,\nonly about 120 data points are found to be enough to predict the three\ndimensional electronic fields accurately, which we ascribe to the symmetry in\nthe problem setup, the use of low-discrepancy sequences for sampling, and\npresence of intrinsic low-dimensional features in the electronic fields. We\ncomment on the interpretability of our machine learning model and discuss its\npossible future applications.",
        "positive": "A phenomenological thermodynamic potential for DyCo$_2$: A phenomenological thermodynamic potential was constructed based on the\nsymmetry analysis and property characterization of bulk DyCo2. An eight-order\npolynomial of Landau expansion was employed to describe the thermodynamic\nbehavior of DyCo2. Several properties were reproduced including ferromagnetic\ntransition temperature, magnetization curve, temperature dependence of\nmagnetization. The transition behavior was analyzed via the thermodynamic\npotential. The Landau phenomenological thermodynamic model predicts the correct\nmetamagnetic transition near the Curie temperature."
    },
    {
        "anchor": "Varying temperature and silicon content in nanodiamond growth: effects\n  on silicon-vacancy centers: Nanodiamonds containing color centers open up many applications in quantum\ninformation processing, metrology, and quantum sensing. In particular, silicon\nvacancy (SiV) centers are prominent candidates as quantum emitters due to their\nbeneficial optical qualities. Here we characterize nanodiamonds produced by a\nhigh-pressure high-temperature method without catalyst metals, focusing on two\nsamples with clear SiV signatures. Different growth temperatures and relative\ncontent of silicon in the initial compound between the samples altered their\nnanodiamond size distributions and abundance of SiV centers. Our results show\nthat nanodiamond growth can be controlled and optimized for different\napplications.",
        "positive": "Screening of the quantum-confined Stark effect in AlN/GaN nanowire\n  superlattices by Germanium doping: We report on electrostatic screening of polarization-induced internal\nelectric fields in AlN/GaN nanowire heterostructures with Germanium-doped GaN\nnanodiscs embedded between AlN barriers. The incorporation of Germanium at\nconcentrations above $10^{20}\\,\\text{cm}^{-3}$ shifts the photoluminescence\nemission energy of GaN nanodiscs to higher energies accompanied by a decrease\nof the photoluminescence decay time. At the same time, the thickness-dependent\nshift in emission energy is significantly reduced. In spite of the high donor\nconcentration a degradation of the photoluminescence properties is not\nobserved."
    },
    {
        "anchor": "A critical examination of robustness and generalizability of machine\n  learning prediction of materials properties: Recent advances in machine learning (ML) methods have led to substantial\nimprovement in materials property prediction against community benchmarks, but\nan excellent benchmark score may not imply good generalization of performance.\nHere we show that ML models trained on the Materials Project 2018 (MP18)\ndataset can have severely degraded prediction performance on new compounds in\nthe Materials Project 2021 (MP21) dataset. We document performance degradation\nin graph neural networks and traditional descriptor-based ML models for both\nquantitative and qualitative predictions. We find the source of the predictive\ndegradation is due to the distribution shift between the MP18 and MP21\nversions. This is revealed by the uniform manifold approximation and projection\n(UMAP) of the feature space. We then show that the performance degradation\nissue can be foreseen using a few simple tools. Firstly, the UMAP can be used\nto investigate the connectivity and relative proximity of the training and test\ndata within feature space. Secondly, the disagreement between multiple ML\nmodels on the test data can illuminate out-of-distribution samples. We\ndemonstrate that the simple yet efficient UMAP-guided and query-by-committee\nacquisition strategies can greatly improve prediction accuracy through adding\nonly 1~\\% of the test data. We believe this work provides valuable insights for\nbuilding materials databases and ML models that enable better prediction\nrobustness and generalizability.",
        "positive": "Transmission conditions for thin curvilinear close to circular\n  heat-resistant interphases in composite ceramics: This paper considers the problem of heat transfer in a composite ceramic\nmaterial where the structural elements are bonded to the matrix via a thin heat\nresistant adhesive layer. The layer has the form of a circular ring or close to\nit. Using an asymptotic approach, the interphase is modeled by an infinitesimal\nimperfect interface, preserving the main features of the temperature fields\naround the interphase, and allowing a significant simplification where FEM\nanalysis is concerned. The nonlinear transmission conditions that accompany\nsuch an imperfect interface are evaluated, and their accuracy is verified by\nmeans of dedicated analytical examples as well as carefully designed FEM\nsimulations. The interphases of various geometries are analysed, with an\nemphasis on the influence of the curvature of their boundaries on the accuracy\nof the evaluated conditions. Numerical results demonstrate the benefits of the\napproach and its limitations."
    },
    {
        "anchor": "Atomic step motion during the dewetting of ultra-thin films: We report on three key processes involving atomic step motion during the\ndewetting of thin solid films: (i) the growth of an isolated island nucleated\nfar from a hole, (ii) the spreading of a monolayer rim, and (iii) the zipping\nof a monolayer island along a straight dewetting front. Kinetic Monte Carlo\nresults are in good agreement with simple analytical models assuming\ndiffusion-limited dynamics.",
        "positive": "Unified theory of the direct or indirect bandgap nature of conventional\n  semiconductors: Although the direct or indirect nature of the bandgap transition is an\nessential parameter of semiconductors for optoelectronic applications, the\nunderstanding why some of the conventional semiconductors have direct or\nindirect bandgaps remains ambiguous. In this Letter, we revealed that the\nexistence of the occupied cation d bands is a prime element in determining the\ndirectness of the bandgap of semiconductors through the s-d and p-d couplings,\nwhich push the conduction band energy levels at the X- and L-valley up, but\nleaves the {\\Gamma}-valley conduction state unchanged. This unified theory\nunambiguously explains why Diamond, Si, Ge, and Al-containing group III-V\nsemiconductors, which do not have active occupied d bands, have indirect\nbandgaps and remaining common semiconductors, except GaP, have direct bandgaps.\nBesides s-d and p-d couplings, bond length and electronegativity of anions are\ntwo remaining factors regulating the energy ordering of the {\\Gamma}-, X-, and\nL-valley of the conduction band, and are responsible for the anomalous bandgap\nbehaviors in GaN, GaP, and GaAs that have direct, indirect, and direct\nbandgaps, respectively, despite the fact that N, P, and As are in ascending\norder of the atomic number. This understanding will shed light on the design of\nnew direct bandgap light-emitting materials."
    },
    {
        "anchor": "Determining the Anisotropic Exchange Coupling of CrO_2 via\n  First-Principles Density Functional Theory Calculations: We report a study of the anisotropic exchange interactions in bulk CrO_2\ncalculated from first principles within density functional theory. We determine\nthe exchange coupling energies, using both the experimental lattice parameters\nand those obtained within DFT, within a modified Heisenberg model Hamiltonian\nin two ways. We employ a supercell method in which certain spins within a cell\nare rotated and the energy dependence is calculated and a spin-spiral method\nthat modifies the periodic boundary conditions of the problem to allow for an\noverall rotation of the spins between unit cells. Using the results from each\nof these methods, we calculate the spin-wave stiffness constant D from the\nexchange energies using the magnon dispersion relation. We employ a Monte Carlo\nmethod to determine the DFT-predicted Curie temperature from these calculated\nenergies and compare with accepted values. Finally, we offer an evaluation of\nthe accuracy of the DFT-based methods and suggest implications of the competing\nferro- and antiferromagnetic interactions.",
        "positive": "Anharmonic lattice dynamics of Ag$_2$O studied by inelastic neutron\n  scattering and first principles molecular dynamics simulations: Inelastic neutron scattering measurements on silver oxide (Ag$_2$O) with the\ncuprite structure were performed at temperatures from 40 to 400\\,K, and Fourier\ntransform far-infrared spectra were measured from 100 to 300\\,K. The measured\nphonon densities of states and the infrared spectra showed unusually large\nenergy shifts with temperature, and large linewidth broadenings. First\nprinciples molecular dynamics (MD) calculations were performed at various\ntemperatures, successfully accounting for the negative thermal expansion (NTE)\nand local dynamics. Using the Fourier-transformed velocity autocorrelation\nmethod, the MD calculations reproduced the large anharmonic effects of Ag$_2$O,\nand were in excellent agreement with the neutron scattering data. The\nquasiharmonic approximation (QHA) was less successful in accounting for much of\nthe phonon behavior. The QHA could account for some of the NTE below 250 K,\nalthough not at higher temperatures. Strong anharmonic effects were found for\nboth phonons and for the NTE. The lifetime broadenings of Ag$_2$O were\nexplained by anharmonic perturbation theory, which showed rich interactions\nbetween the Ag-dominated modes and the O-dominated modes in both up- and\ndown-conversion processes."
    },
    {
        "anchor": "Unraveling the Effect of Electron-Electron Interaction on Electronic\n  Transport in High-Mobility Stannate Films: Contrary to the common belief that electron-electron interaction (EEI) should\nbe negligible in s-orbital-based conductors, we demonstrated that the EEI\neffect could play a significant role on electronic transport leading to the\nmisinterpretation of the Hall data. We show that the EEI effect is primarily\nresponsible for an increase in the Hall coefficient in the La-doped SrSnO3\nfilms below 50 K accompanied by an increase in the sheet resistance. The\nquantitative analysis of the magnetoresistance (MR) data yielded a large phase\ncoherence length of electrons exceeding 450 nm at 1.8 K and revealed the\nelectron-electron interaction being accountable for breaking of electron phase\ncoherency in La-doped SrSnO3 films. These results while providing critical\ninsights into the fundamental transport behavior in doped stannates also\nindicate the potential applications of stannates in quantum coherent electronic\ndevices owing to their large phase coherence length.",
        "positive": "Vicinal metal surfaces as potential catalysts for phosphorene epitaxial\n  growth: Phosphorene, a single layer of black phosphorous (BLK-P), has a significant\npotential for flexible and tunable electronics, but attempts to grow it\nepitaxially have been unsuccessful to date. Meanwhile, hexagonal blue\nphoshorous (BL-P) has been achieved on closed-packed (111) metal surfaces in\nspecial growth conditions of high vapor pressure and high reactivity of\nphosphorous. The (111) surfaces favors BL-P over BLK-P due to its hexagonal\nsymmetry. Here, we investigate computationally the alternative offered by\nstepped substrates. Using the Cu(311) surface as a model, we find that surface\nsteps can favor energetically BLK-P over BL-P. This can be rationalized in\nterms of surface density of states and orbital hybridization, which lead to a\nstronger surface bonding of the lower BLK-P half-layer. This work suggests that\nvicinal metal surfaces of metals can offer a viable path towards phosphorene\nsynthesis."
    },
    {
        "anchor": "Increased hole mobility in anti-ThCr$_2$Si$_2$-type La$_2$O$_2$Bi\n  co-sintered with alkaline earth metal oxides for oxygen intercalation and\n  hole carrier doping: Metallic anti-ThCr$_2$Si$_2$-type $RE_2$O$_2$Bi ($RE$ = rare earth) with Bi\nsquare nets show superconductivity while insulating La$_2$O$_2$Bi shows high\nhole mobility, by expanding the c-axis length through oxygen intercalation. In\nthis study, alkaline earth metal oxides (CaO, SrO, and BaO) were co-sintered\nwith La$_2$O$_2$Bi. CaO and BaO served as oxygen intercalants without\nincorporation of Ca and Ba in La$_2$O$_2$Bi. On the other hand, SrO served as\nnot only oxygen intercalant but also hole dopant via Sr substitution with La in\nLa$_2$O$_2$Bi. The oxygen intercalation and hole doping resulted in expansion\nof the c-axis length, contributing to improved electrical conduction. In\naddition, the hole mobility was enhanced up to 150 cm$^2$V$^{-1}$s$^{-1}$ in\nLa$_2$O$_2$Bi, which almost doubles the mobility in previous study.",
        "positive": "Time-dependent embedding: A method of solving the time-dependent Schr\\\"odinger equation is presented,\nin which a finite region of space is treated explicitly, with the boundary\nconditions for matching the wave-functions on to the rest of the system\nreplaced by an embedding term added on to the Hamiltonian. This time-dependent\nembedding term is derived from the Fourier transform of the energy-dependent\nembedding potential, which embeds the time-independent Schr\\\"odinger equation.\nResults are presented for a one-dimensional model of an atom in a time-varying\nelectric field, the surface excitation of this model atom at a jellium surface\nin an external electric field, and the surface excitation of a bulk state."
    },
    {
        "anchor": "Exchange energies in CoFeB/Ru/CoFeB Synthetic Antiferromagnets: The interlayer exchange coupling confers specific properties to Synthetic\nAntiferromagnets that make them suitable for several applications of\nspintronics. The efficient use of this magnetic configuration requires an\nin-depth understanding of the magnetic properties and their correlation with\nthe material structure. Here we establish a reliable procedure to quantify the\ninterlayer exchange coupling and the intralayer exchange stiffness in synthetic\nantiferromagnets; we apply it to the ultrasmooth and amorphous\nCo$_{40}$Fe$_{40}$B$_{20}$ (5-40 nm)/Ru/ Co$_{40}$Fe$_{40}$B$_{20}$ material\nplatform. The complex interplay between the two exchange interactions results\nin a gradient of the magnetization orientation across the thickness of the\nstack which alters the hysteresis and the spin wave eigenmodes of the stack in\na non trivial way. We measured the field-dependence of the frequencies of the\nfirst four spin waves confined within the thickness of the stack. We modeled\nthese frequencies and the corresponding thickness profiles of these spin waves\nusing micromagnetic simulations. The comparison with the experimental results\nallows to deduce the magnetic parameters that best account for the sample\nbehavior. The exchange stiffness is established to be 16 $\\pm$ 2 pJ/m,\nindependently of the Co$_{40}$Fe$_{40}$B$_{20}$ thickness. The interlayer\nexchange coupling starts from -1.7 mJ/m$^2$ for the thinnest layers and it can\nbe maintained above -1.3 mJ/m$^2$ for CoFeB layers as thick as 40 nm. The\ncomparison of our method with earlier characterizations using the sole\nsaturation fields argues for a need to revisit the tabulated values of\ninterlayer exchange coupling in thick synthetic antiferromagnets.",
        "positive": "First-Principles Study of the Ferroelectric Properties of\n  SrTaO$_2$N/SrTiO$_3$ Interfaces: First-principles calculations based on density-functional theory in the\npseudo-potential approach have been performed for the total energy, crystal\nstructure and cell polarization for SrTaO$_2$N/SrTiO$_3$ heterostructures.\nDifferent heterojunctions were analyzed in terms of the termination atoms at\nthe interface plane, and periodic or non-periodic stacking in the perpendicular\ndirection. The calculations show that the SrTaO$_2$N layer is compressed along\nthe $ab$-plane, while the SrTiO$_3$ is elongated, thus favoring the formation\nof P4mm local environment on both sides of the interface, leading to net\nmacroscopic polarization. The analysis of the local polarization as a function\nof the distance to the interface, for each individual unit cell was found to\ndepend on the presence of a N or an O atom at the interface, and also on the\nasymmetric and not uniform $c$-axis deformation due to the induced strain in\nthe $ab$-plane. The resulting total polarization in the periodic array was $\n\\approx 0.54$ C/m$^2$, which makes this type of arrangement suitable for\nmicroelectronic applications."
    },
    {
        "anchor": "Stacking-dependent exciton multiplicity in WSe$_2$ bilayers: Twisted layers of atomically thin two-dimensional materials realize a broad\nrange of novel quantum materials with engineered optical and transport\nphenomena arising from spin and valley degrees of freedom and strong electron\ncorrelations in hybridized interlayer bands. Here, we report experimental and\ntheoretical studies of WSe$_2$ homobilayers obtained in two stable\nconfigurations of 2H ($60^\\circ$ twist) and 3R ($0^\\circ$ twist) stackings by\ncontrolled chemical vapor synthesis of high-quality large-area crystals. Using\noptical absorption and photoluminescence spectroscopy at cryogenic\ntemperatures, we uncover marked differences in the optical characteristics of\n2H and 3R bilayer WSe$_2$ which we explain on the basis of beyond-DFT\ntheoretical calculations. Our results highlight the role of layer stacking for\nthe spectral multiplicity of momentum-direct intralayer exciton transitions in\nabsorption, and relate the multiplicity of phonon sidebands in the\nphotoluminescence to momentum-indirect excitons with different spin valley and\nlayer character. Our comprehensive study generalizes to other layered\nhomobilayer and heterobilayer semiconductor systems and highlights the role of\ncrystal symmetry and stacking for interlayer hybrid states.",
        "positive": "Ab initio zone-center phonons in LiTaO3: comparison to LiNbO3: The four A1-TO Gamma phonon frequencies in lithium tantalate are calculated\nin the frozen-phonon approach from first principles using the full-potential\nlinearized augmented plane wave method. A good agreement with the experimental\ndata available is found for all modes; reliable displacement pattern of\ndifferent modes becomes available from the calculated eigenvectors. The Raman\nspectra recorded for A1 modes in LiNbO3 exhibit a counter-intuitive softening\nof the A1-TO3 mode frequency with respect to that measured in LiTaO3. We\nexplain this behaviour by a comparatively harder oxygen rotation in LiTaO3 and\ndiscuss other differences in lattice dynamics of these two materials, namely a\nnotably delocalization of Ta and Li contributions over more that one\ncorresponding mode in LiTaO3, which is different from the situation in lithium\nniobate. The Li isotope shift is predicted in the calculation."
    },
    {
        "anchor": "Ab Initio Studies of Liquid and Amorphous Ge: We review our previous work on the dynamic structure factor S(k,omega) of\nliquid Ge (l-Ge) at temperature T = 1250 K, and of amorphous Ge (a-Ge) at T =\n300 K, using ab initio molecular dynamics [Phys. Rev. B67, 104205 (2003)]. The\nelectronic energy is computed using density-functional theory, primarily in the\ngeneralized gradient approximation, together with a plane wave representation\nof the wave functions and ultra-soft pseudopotentials. We use a 64-atom cell\nwith periodic boundary conditions, and calculate averages over runs of up to 16\nps. The calculated liquid S(k,omega) agrees qualitatively with that obtained by\nHosokawa et al, using inelastic X-ray scattering. In a-Ge, we find that the\ncalculated S(k,omega) is in qualitative agreement with that obtained\nexperimentally by Maley et al. Our results suggest that the ab initio approach\nis sufficient to allow approximate calculations of S(k,omega) in both liquid\nand amorphous materials.",
        "positive": "Pressure-induced s-band ferromagnetism in alkali metals: First-principles density-functional-theory calculations show that compression\nof alkali metals stabilizes open structures with localized interstitial\nelectrons which may exhibit a Stoner-type instability towards ferromagnetism.\nWe find ferromagnetic phases of the lithium-IV-type, simple cubic, and simple\nhexagonal structures in the heavier alkali metals, which may be described as\ns-band ferromagnets. We predict that the most stable phases of potassium at low\ntemperatures and pressures around 20 GPa are ferromagnets."
    },
    {
        "anchor": "Carrier Multiplication in Silicon Nanocrystals: Theoretical\n  Methodologies and Role of the Passivation: Carrier multiplication is a non-radiative recombination mechanism that leads\nto the generation of two or more electron-hole pairs after absorption of a\nsingle photon. By reducing the occurrence of dissipative effects, this process\ncan be exploited to increase solar cell performance. In this work we introduce\ntwo different theoretical fully ab-initio tools that can be adopted to study\ncarrier multiplication in nanocrystals. The tools are described in detail and\ncompared. Subsequently we calculate carrier multiplication lifetimes in H- and\nOH- terminated silicon nanocrystals, pointed out the role played by the\npassivation on the carrier multiplication processes.",
        "positive": "Anisotropic conjugated polymer chain conformation tailors the energy\n  migration in nanofibers: Conjugated polymers are complex multi-chromophore systems, with emission\nproperties strongly dependent on the electronic energy transfer through active\nsub-units. Although the packing of the conjugated chains in the solid state is\nknown to be a key factor to tailor the electronic energy transfer and the\nresulting optical properties, most of the current solution-based processing\nmethods do not allow for effectively controlling the molecular order, thus\nmaking the full unveiling of energy transfer mechanisms very complex. Here we\nreport on conjugated polymer fibers with tailored internal molecular order,\nleading to a significant enhancement of the emission quantum yield. Steady\nstate and femtosecond time-resolved polarized spectroscopies evidence that\nexcitation is directed toward those chromophores oriented along the fiber axis,\non a typical timescale of picoseconds. These aligned and more extended\nchromophores, resulting from the high stretching rate and electric field\napplied during the fiber spinning process, lead to improved emission\nproperties. Conjugated polymer fibers are relevant to develop optoelectronic\nplastic devices with enhanced and anisotropic properties."
    },
    {
        "anchor": "Piezoresistance in silicon at uniaxial compressive stresses up to 3 GPa: The room-temperature longitudinal piezoresistance of n-type and p-type\ncrystalline silicon along selected crystal axes is investigated under uniaxial\ncompressive stresses up to 3 GPa. While the conductance ($G$) of n-type silicon\neventually saturates at $\\approx 45%$ of its zero-stress value ($G_0$) in\naccordance with the charge transfer model, in p-type material $G/G_0$ increases\nabove a predicted limit of $\\approx 4.5$ without any significant saturation,\neven at 3 GPa. Calculation of $G/G_0$ using \\textit{ab-initio} density\nfunctional theory reveals that neither $G$ nor the mobility, when properly\naveraged over the hole distribution, saturate at stresses lower than 3 GPa. The\nlack of saturation has important consequences for strained silicon\ntechnologies.",
        "positive": "Decoding the complexities of lead-based relaxor ferroelectrics: Relaxor ferroelectrics, which can exhibit exceptional electromechanical\ncoupling are some of the most important functional materials with applications\nranging from ultrasound imaging to actuators and sensors in\nmicroelectromechanical devices. Since their discovery nearly 60 years ago, the\ncomplexity of nanoscale chemical and structural heterogeneity in these systems\nhas made understanding the origins of their unique electromechanical properties\na seemingly intractable problem. A full accounting of the mechanisms that\nconnect local structure and chemistry with nanoscale fluctuations in\npolarization has, however, remained a need and a challenge. Here, we employ\naberration-corrected scanning transmission electron microscopy (STEM) to\nquantify various types of nanoscale heterogeneity and their connection to local\npolarization in the prototypical relaxor ferroelectric system\nPb(Mg$_{1/3}$Nb$_{2/3}$)O$_{3}$-PbTiO3 (PMN-PT). We identify three main\ncontributions that each depend on Ti content: chemical order, oxygen octahedral\ntilt, and oxygen octahedral distortion. These heterogeneities are found to be\nspatially correlated with low angle polar domain walls, indicating their role\nin disrupting long-range polarization. Specifically, these heterogeneities lead\nto nanoscale domain formation and the relaxor response. We further locate\nnanoscale regions of monoclinic distortion that correlate directly with Ti\ncontent and the electromechanical performance. Through this approach, the\nelusive connection between chemical heterogeneity, structural heterogeneity and\nlocal polarization is revealed, and the results validate models needed to\ndevelop the next generation of relaxor ferroelectric materials."
    },
    {
        "anchor": "High-Mobility Two-Dimensional Electron Gases at Oxide Interfaces:\n  Origins and Opportunities: The discovery of two-dimensional electron gas (2DEG) at well-defined\ninterfaces between insulating complex oxides provides the opportunity for a new\ngeneration of all-oxide electronics. Particularly, the 2DEG at the interface\nbetween two perovskite insulators represented by the formula of ABO3, such as\nLaAlO3 and SrTiO3, has attracted significant attention. In recent years,\nprogresses have been made to decipher the puzzle of the origin of interface\nconduction, to design new types of oxide interfaces, and to improve the\ninterfacial carrier mobility significantly. These achievements open the door to\nexplore fundamental as well as applied physics of complex oxides. Here, we\nreview our recent experimental work on metallic and insulating interfaces\ncontrolled by interfacial redox reactions in SrTiO3-based heterostructures. Due\nto the presence of oxygen-vacancies at the SrTiO3 surface, metallic conduction\ncan be created at room temperature in perovskite-type interfaces when the\noverlayer oxide ABO3 involves Al, Ti, Zr, or Hf elements at the B-sites.\nFurthermore, relying on interface-stabilized oxygen vacancies, we have created\na new type of 2DEG at the heterointerface between SrTiO3 and a spinel\n{\\gamma}-Al2O3 epitaxial film with compatible oxygen ions sublattices. The\nspinel/perovskite oxide 2DEG exhibits an electron mobility exceeding 100,000\ncm2V-1s-1, more than one order of magnitude higher than those of hitherto\ninvestigated perovskite-type interfaces. Our findings pave the way for design\nof high-mobility all-oxide electronic devices and open a route towards studies\nof mesoscopic physics with complex oxides.",
        "positive": "Intrinsic local symmetry-breaking in nominally cubic paraelectric BaTiO3: Whereas low-temperature ferroelectrics have a well understood ordered spatial\ndipole arrangement, the fate of these dipoles in paraelectric phases remains\npoorly understood. Using density functional theory (DFT), we find that unlike\nthe case in conventional non-polar ABO$_3$ compounds illustrated here for cubic\nBaZrO$_3$, the origin of the distribution of the B site off-centering in cubic\nparaelectric such as BaTiO$_3$ is an intrinsic, energy stabilizing symmetry\nbreaking. Minimizing the internal energy E of a constrained cubic phase already\nreveals the formation of a distribution of intrinsic local displacements that\n(i) mimic the symmetries of the low temperature phases, while (ii) being the\nprecursors of what finite temperature DFT Molecular Dynamics finds as thermal\nmotifs. The implications of such symmetry breaking on the microscopic\nstructures and anomalous properties in these kinds of PE materials are\ndiscussed."
    },
    {
        "anchor": "Voltage Tunable Plasmon Propagation in Dual Gated Bilayer Graphene: In this paper, we theoretically investigate plasmon propagation\ncharacteristics in AB and AA stacked bilayer graphene (BLG) in the presence of\nenergy asymmetry due to an electrostatic field oriented perpendicularly to the\nplane of the graphene sheet. We first derive the optical conductivity of BLG\nusing the Kubo formalism incorporating energy asymmetry and finite electron\nscattering. All results are obtained for room temperature (300K) operation. By\nsolving Maxwell's equations in a dual gate device setup, we obtain the\nwavevector of propagating plasmon modes in the transverse electric (TE) and\ntransverse magnetic (TM) directions at terahertz frequencies. The plasmon\nwavevector allows us to compare the compression factor, propagation length, and\nthe mode confinement of TE and TM plasmon modes in bilayer and monolayer\ngraphene sheets and also study the impact of material parameters on plasmon\ncharacteristics. Our results show that the energy asymmetry can be harnessed to\nincrease the propagation length of TM plasmons in BLG. AA stacked BLG shows a\nlarger increase in propagation length than AB stacked BLG; conversely, it is\nvery insensitive to the Fermi level variations. Additionally, the dual gate\nstructure allows independent modulation of the energy asymmetry and the Fermi\nlevel in BLG, which is advantageous for reconfiguring plasmon characteristics\npost device fabrication.",
        "positive": "Atomic moments in Mn2CoAl thin films analyzed by X-ray magnetic circular\n  dichroism: Spin gapless semiconductors are known to be strongly affected by structural\ndisorder when grown epitaxially as thin films. The magnetic properties of\nMn2CoAl thin films grown on GaAs (001) substrates are investigated here as a\nfunction of annealing. This study investigates the atomic-specific magnetic\nmoments of Mn and Co atoms measured through X-ray magnetic circular dichroism\nas a function of annealing and the consequent structural ordering. The results\nindicate that the structural distortion mainly affects the Mn atoms as seen by\nthe reduction of the magnetic moment from its predicted value."
    },
    {
        "anchor": "Lineshape of harmonic generation on metal nanoparticles and metallic\n  Photonic Crystal slabs: We study the linear- and nonlinear-optical lineshapes of metal nanoparticles\n(theory) and metallic photonic crystal slabs (experiment and theory). For metal\nnanoparticle ensembles, we show analytically and numerically that femtosecond\nsecond- or third-harmonic-generation (THG) experiments together with linear\nextinction measurements generally do not allow to determine the homogeneous\nlinewidth. This is in contrast to claims of previous work in which we identify\na technical mistake. For metallic photonic crystal slabs, we introduce a simple\nclassical model of two coupled Lorentz oscillators, corresponding to the\nplasmon and waveguide modes. This model describes very well the key\nexperimental features of linear optics, particularly the Fano-like lineshapes.\nThe derived nonlinear-optical THG spectra are shown to depend on the underlying\nsource of the optical nonlinearity. We present corresponding THG experiments\nwith metallic photonic crystal slabs. In contrast to previous work, we\nspectrally resolve the interferometric THG signal, and we additionally obtain a\nhigher temporal resolution by using 5 fs laser pulses. In the THG spectra, the\ndistinct spectral components exhibit strongly different behaviors versus time\ndelay. The measured spectra agree well with the model calculations.",
        "positive": "Computational study of structural, electronic and optical properties of\n  crystalline NH$_4$N$_3$: A systematic computational study on the structural, electronic, bonding, and\noptical properties of orthorhombic ammonium azide (NH$_4$N$_3$) has been\nperformed using planewave pseudopotential (PW-PP) method based on density\nfunctional theory (DFT). Semiempirical dispersion correction schemes have been\nused to account for non-bonded interactions in molecular crystalline\nNH$_4$N$_3$. The ground state lattice parameters and fractional co-ordinates\nobtained using the dispersion correction schemes are in excellent agreement\nwith experimental results. We calculated the single crystal elastic constants\nof NH$_4$N$_3$ and its sensitivity is interpreted through the observed ordering\nof the elastic constants (C$_{33}$ $>$ C$_{11}$ $>$ C$_{22}$). The electronic\nstructure and optical properties were calculated using full potential\nlinearized augmented plane wave (FP-LAPW) approach with recently developed\nfunctional of Tran-Blaha modified Becke-Johnson (TB-mBJ) potential. The TB-mBJ\nelectronic structure shows that NH$_4$N$_3$ is a direct band gap insulator with\na band gap of 5.08 eV, while the calculated band gap with standard generalized\ngradient approximation is found to be 4.10 eV. The optical anisotropy is\nanalyzed through the calculated optical constants namely dielectric function\nand refractive index along three different crystallographic axes. The\nabsorption spectra reveal that NH$_4$N$_3$ is sensitive to ultraviolet (UV)\nlight. Further, we also analyzed the detonation characteristics of the\nNH$_4$N$_3$ using the reported heat of formation and calculated density.\nNH$_4$N$_3$ is found to have a detonation velocity of 6.45 km/s and a\ndetonation pressure about 15.16 GPa computed by Kamlet-Jacobs empirical\nequations."
    },
    {
        "anchor": "Application of topological quantum chemistry in electrides: The recently developed theory of topological quantum chemistry (TQC) has\nbuilt a close connection between band representations in momentum space and\norbital characters in real space. It provides an effective way to diagnose\ntopological materials, leading to the discovery of lots of topological\nmaterials after the screening of all known nonmagnetic compounds. On the other\nhand, it can also efficiently reveal spacial orbital characters, including\naverage charge centers and site-symmetry characters. By using TQC theory with\nthe computed irreducible representations in the first-principles calculations,\nwe demonstrate that the electrides with excess electrons serving as anions at\nvacancies can be well identified by analyzing band representations (BRs), which\ncannot be expressed as a sum of atomic-orbital-induced band representations\n(aBRs). In fact, the floating bands (formed by the excess electrons) belong to\nthe BRs induced from the \"pseudo-orbitals\" centered at vacancies. In other\nwords, the electrides are proved to be unconventional ionic crystals, where a\nset of occupied bands is not a sum of aBRs but necessarily contains a BR from\nvacancies. The TQC theory provides a promising avenue to pursue more electride\ncandidates in ionic crystals.",
        "positive": "Broadband microwave and time-domain terahertz spectroscopy of CVD grown\n  graphene: We report a study of the complex AC impedance of CVD grown graphene. We\nmeasure the explicit frequency dependence of the complex impedance and\nconductance over the microwave and terahertz range of frequencies using our\nrecently developed broadband microwave Corbino and time domain terahertz\nspectrometers (TDTS). We demonstrate how one may resolve a number of technical\ndifficulties in measuring the intrinsic impedance of the graphene layer that\nthis frequency range presents, such as distinguishing contributions to the\nimpedance from the substrate. From our microwave measurements, the AC impedance\nhas little dependance on temperature and frequency down to liquid helium\ntemperatures. The small contribution to the imaginary impedance comes from\neither a remaining residual contribution from the substrate or a small\ndeviation of the conductance from the Drude form."
    },
    {
        "anchor": "Potassium under pressure: electronic origin of complex structures: Recent high-pressure x-ray diffraction studies of alkali metals revealed\nunusual complex structures that follow the body-centered and face-centered\ncubic structures on compression. The structural sequence of potassium under\ncompression to 1 Megabar is as follows: bcc - fcc - h-g (tI19*), hP4 - oP8 -\ntI4 - oC16. We consider configurations of Brillouin-Jones zones and the Fermi\nsurface within a nearly-free-electron model in order to analyze the importance\nof these configurations for the crystal structure energy that contains two main\ncontributions: electrostatic (Ewald) and electronic (band structure) energies.\nThe latter can be lowered due to a formation of Brillouin zone planes close to\nthe Fermi surface opening an energy gap at these planes. Under pressure, the\nband structure energy term becomes more important leading to a formation of\ncomplex low-symmetry structures. The stability of the post-fcc phases in K is\nattributed to the changes in the valence electron configuration implying the\noverlap of valence band with the upper core electrons. This effect offers an\nunderstanding of structural complexity of alkali metals under strong\ncompression.",
        "positive": "First-principles thermodynamics of CsSnI3: CsSnI3 is a promising eco-friendly solution for energy harvesting\ntechnologies. It exists at room temperature in either a black perovskite\npolymorph or a yellow 1D double-chain, which irreversibly deteriorates in the\nair. In this work, we unveil the relative thermodynamic stability between the\ntwo structures with a first-principles sampling of the CsSnI3\nfinite-temperature phase diagram, discovering how it is driven by anomalously\nlarge quantum and anharmonic ionic fluctuations. Thanks to a comprehensive\ntreatment of anharmonicity, the simulations deliver a remarkable agreement with\nknown experimental data for the transition temperatures of the orthorhombic,\nrhombohedral, and cubic perovskite structures and the thermal expansion\ncoefficient. We disclose how the perovskite polymorphs are the ground state\nabove \\SI{270}{\\kelvin} and discover an abnormal decrease in heat capacity upon\nheating in the cubic black perovskite. Our results also significantly downplay\nthe Cs+ rattling modes' contribution to mechanical instability. The remarkable\nagreement with experiments validates our methodology, which can be\nsystematically applied to all metal halides."
    },
    {
        "anchor": "Long-Lived Charge Separation Following Pump-Energy Dependent Ultrafast\n  Charge Transfer in Graphene/WS$_2$ Heterostructures: Van der Waals heterostructures consisting of graphene and transition metal\ndichalcogenides (TMDCs) have recently shown great promise for high-performance\noptoelectronic applications. However, an in-depth understanding of the critical\nprocesses for device operation, namely interfacial charge transfer (CT) and\nrecombination, has so far remained elusive. Here, we investigate these\nprocesses in graphene-WS$_2$ heterostructures, by complementarily probing the\nultrafast terahertz photoconductivity in graphene and the transient absorption\ndynamics in WS$_2$ following photoexcitation. We find that CT across\ngraphene-WS$_2$ interfaces occurs via photo-thermionic emission for\nsub-A-exciton excitation, and direct hole transfer from WS$_2$ to the valence\nband of graphene for above-A-exciton excitation. Remarkably, we observe that\nseparated charges in the heterostructure following CT live extremely long:\nbeyond 1 ns, in contrast to ~1 ps charge separation reported in previous\nstudies. This leads to efficient photogating of graphene. These findings\nprovide relevant insights to optimize further the performance of optoelectronic\ndevices, in particular photodetection.",
        "positive": "Anomalous Nernst effect in compensated ferrimagnetic CoxGd1-x films: The anomalous Nernst effect (ANE) is one of the most intriguing\nthermoelectric phenomena which has attracted growing interest both for its\nunderlying physics and potential applications. Typically, a large ANE response\nis observed in magnets with pronounced magnetizations or nontrivial Berry\ncurvature. Here, we report a significant ANE signal in compensated\nferrimagnetic CoxGd1-x alloy films, which exhibit vanishingly small\nmagnetization. In particular, we found that the polarity of ANE signal is\ndominated by the magnetization orientation of the transition metal Co\nsublattices, rather than the net magnetization of CoxGd1-x films. This\nobservation is not expected from the conventional understanding of ANE but is\nanalogous to the anomalous Hall effect in compensated ferrimagnets. We\nattribute the origin of ANE and its Co-dominant property to the Co-dominant\nBerry curvature. Our work could trigger a more comprehensive understanding of\nANE and may be useful for building energy-harvesting devices by employing ANE\nin compensated ferrimagnets."
    },
    {
        "anchor": "Room Temperature Intrinsic Ferromagnetism in Epitaxial Manganese\n  Selenide Films in the Monolayer Limit: Monolayer van der Waals (vdW) magnets provide an exciting opportunity for\nexploring two-dimensional (2D) magnetism for scientific and technological\nadvances, but the intrinsic ferromagnetism has only been observed at low\ntemperatures. Here, we report the observation of room temperature\nferromagnetism in manganese selenide (MnSe$_x$) films grown by molecular beam\nepitaxy (MBE). Magnetic and structural characterization provides strong\nevidence that in the monolayer limit, the ferromagnetism originates from a vdW\nmanganese diselenide (MnSe$_2$) monolayer, while for thicker films it could\noriginate from a combination of vdW MnSe$_2$ and/or interfacial magnetism of\n$\\alpha$-MnSe(111). Magnetization measurements of monolayer MnSe$_x$ films on\nGaSe and SnSe$_2$ epilayers show ferromagnetic ordering with large saturation\nmagnetization of ~ 4 Bohr magnetons per Mn, which is consistent with density\nfunctional theory calculations predicting ferromagnetism in monolayer\n1T-MnSe$_2$. Growing MnSe$_x$ films on GaSe up to high thickness (~ 40 nm)\nproduces $\\alpha$-MnSe(111), and an enhanced magnetic moment (~ 2x) compared to\nthe monolayer MnSe$_x$ samples. Detailed structural characterization by\nscanning transmission electron microscopy (STEM), scanning tunneling microscopy\n(STM), and reflection high energy electron diffraction (RHEED) reveal an abrupt\nand clean interface between GaSe(0001) and $\\alpha$-MnSe(111). In particular,\nthe structure measured by STEM is consistent with the presence of a MnSe$_2$\nmonolayer at the interface. These results hold promise for potential\napplications in energy efficient information storage and processing.",
        "positive": "Thermoelectric Transport in Weyl Semimetal BaMnSb2: a First-Principles\n  Study: Topological materials are often associated with exceptional thermoelectric\nproperties. Orthorhombic BaMnSb2 is a topological semimetal consisting of\nalternating layers of Ba, Sb, and MnSb. A recent experiment demonstrates that\nBaMnSb2 has a low thermal conductivity and modest thermopower, promising as a\nthermoelectric material. Through first-principles calculations with Coulomb\nrepulsion and spin-orbit coupling included, we studied the electronic\nstructure, phononic structure, and thermoelectric transport properties of\nBaMnSb2 in depth. We find that BaMnSb2 exhibits a low lattice thermal\nconductivity, owing to the scattering of the acoustic phonons with\nlow-frequency optical modes. Using the linearized Boltzmann transport theory\nwith a constant relaxation time approximation, the thermopower is further\ncalculated and an intriguing goniopolar transport behavior, which is associated\nwith both n-type and p-type conduction along separate transport directions\nsimultaneously, is observed. We propose that the figure of merit can be\nenhanced via doping in which electrical conductivity is decreased while the\nthermopower remains undiminished. BaMnSb2 is a potential platform for\nelucidating complex band structure effects and topological phenomena, paving\nthe way to explore rich physics in low-dimensional systems."
    },
    {
        "anchor": "Effect of oxygen concentration on the structural and magnetic properties\n  of LaRh1/2Mn1/2O3 thin films: Epitaxial LaRh1/2Mn1/2O3 thin films have been grown on (001)-oriented LaAlO3\nand SrTiO3 substrates using pulsed laser deposition. The optimized thin film\nsamples are semiconducting and ferromagnetic with a Curie temperature close to\n100 K, a coercive field of 1200 Oe, and a saturation magnetization of 1.7muB\nper formula unit. The surface texture, structural, electrical, and magnetic\nproperties of the LaRh1/2Mn1/2O3 films was examined as a function of the oxygen\nconcentration during deposition. While an elevated oxygen concentration yields\nthin films with optimal magnetic properties, slightly lower oxygen\nconcentrations result in films with improved texture and crystallinity.",
        "positive": "Ultrafast Optical Nonlinearity in PMMA-TiO2 Nanocomposites: With 780-nm, 250-fs laser pulses, ultrafast optical nonlinearity has been\nobserved in a series of thin films containing PMMA-TiO2 nanocomposites, which\nare synthesized by a simple technique of in-situ sol-gel/polymerization. The\nbest figures of merit are found in one of the films prepared with a 60% weight\npercentage of titanium isopropoxide. TEM shows the presence of the\n5-nm-diameter particles in the film. The observed optical nonlinearity has a\nrecovery time of ~1.5 ps. These findings suggest the strong potential of\nPMMA-TiO2 nanocomposites for all-optical switching."
    },
    {
        "anchor": "Disorder-induced magnetic memory: Experiments and theories: Beautiful theories of magnetic hysteresis based on random microscopic\ndisorder have been developed over the past ten years. Our goal was to directly\ncompare these theories with precise experiments. We first developed and then\napplied coherent x-ray speckle metrology to a series of thin multilayer\nperpendicular magnetic materials. To directly observe the effects of disorder,\nwe deliberately introduced increasing degrees of disorder into our films. We\nused coherent x-rays to generate highly speckled magnetic scattering patterns.\nThe apparently random arrangement of the speckles is due to the exact\nconfiguration of the magnetic domains in the sample. In effect, each speckle\npattern acts as a unique fingerprint for the magnetic domain configuration.\nSmall changes in the domain structure change the speckles, and comparison of\nthe different speckle patterns provides a quantitative determination of how\nmuch the domain structure has changed. How is the magnetic domain configuration\nat one point on the major hysteresis loop related to the configurations at the\nsame point on the loop during subsequent cycles? The microscopic return-point\nmemory(RPM) is partial and imperfect in the disordered samples, and completely\nabsent when the disorder was not present. We found the complementary-point\nmemory(CPM) is also partial and imperfect in the disordered samples and\ncompletely absent when the disorder was not present. We found that the RPM is\nalways a little larger than the CPM. We also studied the correlations between\nthe domains within a single ascending or descending loop. We developed new\ntheoretical models that do fit our experiments.",
        "positive": "\"Madelung model\" prediction for dependence of lattice parameter on\n  nanocrystal size: The competition between the long range Coulomb attractive and the short range\nrepulsive interaction in ionic nanocrystals creates an effective negative\npressure, which causes the lattice parameter a to increase with decreasing\nnanoparticle size d. A simple ``Madelung model'' is used to predict the\ndependence of the lattice parameter for CeO2 and BaTiO3 on d, delta a/a =\nalpha/d, for alpha = 0.22 A and 0.18 A respectively. The model predictions are\ncompared with experimental results."
    },
    {
        "anchor": "Highly efficient room-temperature nonvolatile magnetic switching by\n  current in Fe3GaTe2 thin flakes: Effectively tuning magnetic state by using current is essential for novel\nspintronic devices. Magnetic van der Waals (vdW) materials have shown superior\nproperties for the applications of magnetic information storage based on the\nefficient spin torque effect. However, for most of known vdW ferromagnets, the\nferromagnetic transition temperatures lower than room temperature strongly\nimpede their applications and the room-temperature vdW spintronic device with\nlow energy consumption is still a long-sought goal. Here, we realize the highly\nefficient room-temperature nonvolatile magnetic switching by current in a\nsingle-material device based on vdW ferromagnet Fe3GaTe2. Moreover, the\nswitching current density and power dissipation are about 300 and 60000 times\nsmaller than conventional spin-orbit-torque devices of magnet/heavymetal\nheterostructures. These findings make an important progress on the applications\nof magnetic vdW materials in the fields of spintronics and magnetic information\nstorage.",
        "positive": "Graphene/Au(111) interaction studied by scanning tunneling microscopy: We have used scanning tunneling microscopy to study the structure of graphene\nislands on Au(111) grown by deposition of elemental carbon at 950{\\deg}C.\nConsistent with low-energy electron microscopic observations, we find that the\ngraphene islands have dendritic shapes. The islands tend to cover depressed\nregions of the Au surface, suggesting that Au is displaced as the graphene\ngrows. If small tunneling currents are used, it is possible to image\nsimultaneously the graphene/Au moir\\'e and the Au herringbone reconstruction,\nwhich forms underneath the graphene on cooling from the growth temperature. The\ndelicate herringbone structure and its periodicity remain unchanged from the\nbare Au surface. Using a Frenkel-Kontorova model we deduce that this striking\nobservation is consistent with an attraction between graphene and Au of less\nthan 13 meV per C atom. Raman spectroscopy supports this weak interaction.\nHowever, at the tunneling currents necessary for atomic resolution image of\ngraphene, the Au reconstruction is altered, implying influential tip-sample\ninteractions and a mobile Au surface beneath the graphene."
    },
    {
        "anchor": "Realization of Quantum Spin Hall State in Monolayer 1T'-WTe2: A quantum spin Hall (QSH) insulator is a novel two-dimensional quantum state\nof matter that features quantized Hall conductance in the absence of magnetic\nfield, resulting from topologically protected dissipationless edge states that\nbridge the energy gap opened by band inversion and strong spin-orbit coupling.\nBy investigating electronic structure of epitaxially grown monolayer 1T'-WTe2\nusing angle-resolved photoemission (ARPES) and first principle calculations, we\nobserve clear signatures of the topological band inversion and the band gap\nopening, which are the hallmarks of a QSH state. Scanning tunneling microscopy\nmeasurements further confirm the correct crystal structure and the existence of\na bulk band gap, and provide evidence for a modified electronic structure near\nthe edge that is consistent with the expectations for a QSH insulator. Our\nresults establish monolayer 1T'-WTe2 as a new class of QSH insulator with large\nband gap in a robust two-dimensional materials family of transition metal\ndichalcogenides (TMDCs).",
        "positive": "Revisiting the (110) Surface Structure of TiO2: A Detailed Theoretical\n  Analysis: A detailed reexamination of the (110) surface structure of rutile TiO2 has\nbeen carried out using first-principles total-energy methods. This\ninvestigation is in response to a recent high-precision LEED-IV measurement\nrevealing certain significant quantitative discrepancies between experiment and\nprevious theoretical calculations. We have been able to resolve these\ndiscrepancies and achieve excellent quantitative agreement with experiment by\njudicious attention to reducing computational approximation errors. Our\nanalysis also reveals that bond lengths converge much faster with slab\nthickness than do relaxed absolute atomic positions, which are the structural\nparameters typically reported in the literature for this and related systems.\nThe effect this observation has on both the choice of slab models and the way\nin which surfaces structures should be reported for covalently bonded solids is\ndiscussed. Finally, the efficacy of freezing the lowest several atomic layers\nof TiO2 slab models in their bulk-like positions is examined."
    },
    {
        "anchor": "Non-Close-Packed Three-Dimensional Quasicrystals: Quasicrystals are frequently encountered in condensed matter. They are\nimportant candidates for equilibrium phases from the atomic scale to the\nnanoscale. Here, we investigate the computational self-assembly of four\nquasicrystals in a single model system of identical particles interacting with\na tunable isotropic pair potential. We reproduce a known icosahedral\nquasicrystal and report a decagonal quasicrystal, a dodecagonal quasicrystal,\nand an octagonal quasicrystal. The quasicrystals have low coordination number\nor occur in systems with mesoscale density variations. We also report a network\ngel phase.",
        "positive": "Describing condensed matter from atomically resolved imaging data: from\n  structure to generative and causal models: The development of high-resolution imaging methods such as electron and\nscanning probe microscopy and atomic probe tomography have provided a wealth of\ninformation on structure and functionalities of solids. The availability of\nthis data in turn necessitates development of approaches to derive quantitative\nphysical information, much like the development of scattering methods in the\nearly XX century which have given one of the most powerful tools in condensed\nmatter physics arsenal. Here, we argue that this transition requires adapting\nclassical macroscopic definitions, that can in turn enable fundamentally new\nopportunities in understanding physics and chemistry. For example, many\nmacroscopic definitions such as symmetry can be introduced locally only in a\nBayesian sense, balancing the prior knowledge of materials' physics and\nexperimental data to yield posterior probability distributions. At the same\ntime, a wealth of local data allows fundamentally new approaches for the\ndescription of solids based on construction of statistical and physical\ngenerative models, akin to Ginzburg-Landau thermodynamic models. Finally, we\nnote that availability of observational data opens pathways towards exploring\ncausal mechanisms underpinning solid structure and functionality."
    },
    {
        "anchor": "Magnetization switching induced by spin-orbit torque from Co2MnGa\n  magnetic Weyl semimetal thin films: This study reports the magnetization switching induced by spin-orbit torque\n(SOT) from the spin current generated in Co2MnGa magnetic Weyl semimetal (WSM)\nthin films. We deposited epitaxial Co2MnGa thin films with highly B2-ordered\nstructure on MgO(001) substrates. The SOT was characterized by harmonic Hall\nmeasurements in a Co2MnGa/Ti/CoFeB heterostructure and a relatively large spin\nHall efficiency of -7.8% was obtained.The SOT-induced magnetization switching\nof the perpendicularly magnetized CoFeB layer was further demonstrated using\nthe structure. The symmetry of second harmonic signals, thickness dependence of\nspin Hall efficiency, and shift of anomalous Hall loops under applied currents\nwere also investigated. This study not only contributes to the understanding of\nthe mechanisms of spin-current generation from magnetic-WSM-based\nheterostructures, but also paves a way for the applications of magnetic WSMs in\nspintronic devices.",
        "positive": "Transformation-mediated Plasticity in CuZr based Metallic Glass\n  Composites: A Quantitative Mechanistic Understanding: In this paper, we present a thorough stress analysis of the Cu-Zr\nmetallic-glass composite with embedded B2 particles subject to a martensitic\ntransformation. Within the framework of the Eshelby theory, we are able to\nexplain, in a quantitative manner, (1) the formation of three types of shear\nbands with distinct morphologies as observed experimentally in the severely\ndeformed Cu-Zr metallic-glass composite and (2) the work hardening ability of\nthe Cu-Zr metallic-glass composite as related to the coupled effects of elastic\nback stress and elastic mismatch caused by the martensitic transformation.\nFurthermore, we also discuss the issues about the stress affected zone of the\nindividual B2 phase and the stability of the crystalline-amorphous interface.\nGiven the general agreement between the theoretical and experimental findings,\nwe believe that the outcome of our current work can lead to a deeper\nunderstanding of the transformation-induced plasticity in the Cu-Zr based\nmetallic glass composites, which should be very useful to the design of the\nmetallic-glass composites with improved ductility."
    },
    {
        "anchor": "Borderline Magnetism: How Does Adding Magnesium to Paramagnetic CeCo$_3$\n  Make a 450 K Ferromagnet with Large Magnetic Anisotropy?: A recent experimental study (Phys. Rev. Appl. 9, 024023, 2018) on\nparamagnetic CeCo$_3$ finds that Magnesium alloying induces a ferromagnetic\ntransition with intrinsic properties large enough for permanent magnet\napplications. Here we explain these surprising results \\textit{via} a first\nprinciples study of the electronic structure and magnetism of Magnesium-alloyed\nCeCo$_3$. We find the origin of this Magnesium-induced ferromagnetic transition\nto be Stoner physics - the substantial increase in the Fermi-level\ndensity-of-states $N(E_F)$ with Mg alloying. Our calculations suggest that both\nCe and Co atoms are important for generating large magnetic anisotropy\nsuggesting the viability of Co-3$d$, and Ce-4$f$ interaction for the generation\nof magnetic anisotropy in magnetic materials. These results offer a new route\nto the discovery of ferromagnetic materials and provide fundamental insight\ninto the magnetic properties of these alloys",
        "positive": "Spin-transfer switching and low-field precession in exchange-biased spin\n  valve nano-pillars: Using a three-dimensional focused-ion beam lithography process we have\nfabricated nanopillar devices which show spin transfer torque switching at zero\nexternal magnetic fields. Under a small in-plane external bias field, a\nfield-dependent peak in the differential resistance versus current is observed\nsimilar to that reported in asymmetrical nanopillar devices. This is\ninterpreted as evidence for the low-field excitation of spin waves which in our\ncase is attributed to a spin-scattering asymmetry enhanced by the IrMn exchange\nbias layer coupled to a relatively thin CoFe fixed layer."
    },
    {
        "anchor": "Impact ionization in InSb probed by THz-pump THz-probe spectroscopy: Picosecond carrier dynamics in indium antimonide (InSb) following excitation\nby below-bandgap broadband far infrared radiation were investigated at 200 K\nand 80 K. Using a novel THz-pump/THz-probe scheme with pump THz fields of 100\nkV/cm and an intensity of 100 MW/cm^2, we observed carrier heating and impact\nionization. The number of carriers produced exceeds 10^16 cm-3, corresponding\nto a change in carrier density Delta N/N of 700% at 80K. The onset of a well\ndefined absorption peak at 1.2 THz is an indication of changes in LO and LA\nphonon populations due to cooling of the hot electrons.",
        "positive": "Density functional perturbation theory for gated two-dimensional\n  heterostructures: Theoretical developments and application to flexural\n  phonons in graphene: The ability to perform first-principles calculations of electronic and\nvibrational properties of two-dimensional heterostructures in a field-effect\nsetup is crucial for the understanding and design of next-generation devices.\nWe present here an implementation of density functional perturbation theories\ntailored for the case of two-dimensional heterostructures in field-effect\nconfiguration. Key ingredients are the inclusion of a truncated Coulomb\ninteraction in the direction perpendicular to the slab and the possibility of\nsimulating charging of the slab via field-effects. With this implementation we\ncan access total energies, force and stress tensors, the vibrational properties\nand the electron-phonon interaction. We demonstrate the relevance of the method\nby studying flexural acoustic phonons and their coupling to electrons in\ngraphene doped by field-effect. In particular, we show that while the\nelectron-phonon coupling to those phonons can be significant in neutral\ngraphene, it is strongly screened and negligible in doped graphene, in\ndisagreement with other recent first-principles reports. Consequently, the\ngate-induced coupling with flexural acoustic modes would not be detectable in\ntransport measurements on doped graphene."
    },
    {
        "anchor": "Controlling magnetization reversal in Co/Pt nanostructures with\n  perpendicular anisotropy: We demonstrate a simple method to tailor the magnetization reversal\nmechanisms of Co/Pt multilayers by depositing them onto large area nanoporous\nanodized alumina (AAO) with various aspect ratios, A = pore depth/diameter.\nMagnetization reversal of composite (Co/Pt)/AAO films with large A is governed\nby strong domain-wall pinning which gradually transforms into a\nrotation-dominated reversal for samples with smaller A, as investigated by a\nfirst-order reversal curve method in conjunction with analysis of the angular\ndependent switching fields. The change of the magnetization reversal mode is\nattributed to topographical changes induced by the aspect ratio of the AAO\ntemplates.",
        "positive": "Tailoring the magnetic landscape in Al-doped LaMnO3: An experimental and\n  computational perspective: We have presented the synthesis, structural, and magnetic properties from the\nexperimental point of view. Then we verified our experimental observation by\nstudying the electronic and magnetic properties of Al-doped LaMnO3 from the\nfirst principle density functional theory (DFT) and Monte-Carlo simulation. We\nhave synthesized the LaAlxMn1-xO3 (x= 0.05, 0.15, 0.25) and performed the\nRietveld refinement of XRD data to determine the lattice parameters. To see the\nmixed valance of Mn-ion, we performed the XPS of 25% Al-doped material. The\nmagnetic study shows the ferromagnetic transition of these materials. Using XRD\nrefinement values, we have completed the DFT calculations. The Monte Carlo\nsimulation has been done through the anisotropic Ising model to analyze the\norigin of magnetic transition. We have determined the anisotropy and the\ninteraction constants from the DFT calculations."
    },
    {
        "anchor": "Effect of bonding of a CO molecule on the conductance of atomic metal\n  wires: We have measured the effect of bonding of a CO molecule on the conductance of\nAu, Cu, Pt, and Ni atomic contacts at 4.2 K. When CO gas is admitted to the\nmetal nano contacts, a conductance feature appears in the conductance histogram\nnear 0.5 of the quantum unit of conductance, for all metals. For Au, the\nintensity of this fractional conductance feature can be tuned with the bias\nvoltage, and it disappears at high bias voltage (above $\\sim$ 200 mV). The\nbonding of CO to Au appears to be weakest, and associated with monotomic Au\nwire formation.",
        "positive": "Graphene and Carbon Nanotube Hybrid Structure: A Review: Graphene has been reported with record-breaking properties which have opened\nup huge potential applications. Considerable amount of researches have been\ndevoted to manipulating or modify the properties of graphene to target a more\nsmart nanoscale device. Graphene and carbon nanotube hybrid structure (GNHS) is\none of the promising graphene derivate. The synthesis process and the\nmechanical properties are essential for the GNHS based devices. Therefore, this\nreview will summarise the recent progress of the highly ordered GNHS\nsynthesis/assembly, and discuss the mechanical properties of GNHS under various\nconditions as obtained from molecular dynamics simulations."
    },
    {
        "anchor": "Origin of reversible and irreversible atomic-scale rearrangements in a\n  model two-dimensional network glass: In this contribution, we investigate the fundamental mechanism of plasticity\nin a model two-dimensional network glass. The glass is generated by using a\nMonte Carlo bond-switching algorithm and subjected to athermal simple shear\ndeformation, followed by subsequent unloading at selected deformation states.\nThis enables us to investigate the topological origin of reversible and\nirreversible atomic-scale rearrangements. It is shown that some events that are\ntriggered during loading recover during unloading, while some do not. Thus, two\nkinds of elementary plastic events are observed, which can be linked to the\nnetwork topology of the model glass.",
        "positive": "Photoinduced electrification of solids. III. Temperature dependences: Two preceding parts of a paper (cond-mat/0508457, cond-mat/0508460)\nconsidered the heuristic values of recent experiments pointing to the nearly\nuniversal occurrence of photovoltages across solid surfaces under short-circuit\nconditions. These voltages arise by virtue of a variety of spectrally-dependent\nmechanisms activated by incident photons. For the visible range, the\nphotovoltages are obliged to the photodetachment of ions which leave the\nsurface charged. In an attempt to learn more, we now study short-circuit\nphotovoltages in well-defined materials including high-Tc superconductors\nwithin a broad temperature range down to liquid nitrogen. We believe our data\nprovide a new insight into the process."
    },
    {
        "anchor": "X-ray Diffraction Analysis of Cu2+ Doped Zn1-xCuxFe2O4 Spinel\n  Nanoparticles using Williamson-Hall Plot Method: The nanoparticles (NPs) of Zn1-xCuxFe2O4 (ZCFO) spinels with x = 0, 0.2, 0.4,\n0.6 and 0.8 were synthesized by a sol-gel combustion method using acetate\nprecursor. The NPs of ZCFO were prepared by following calcination process at\n600C for 8hrs. The synthesized NPs of ZCFO were characterized by X-ray\ndiffraction (XRD) analysis using Rietveld refinement. The Rietveld refinement\nof the XRD patterns revealed that the ZCFO spinels crystallize into single\ndiamond cubic structure with Fd-3m space group. The lattice constant and unit\ncell volume for ZCFO NPs shrink with enhancing doping concentration of Cu2+\nion. The crystalline growth in the NPs of ZCFO was examined by peak broadening\npresent in the XRD pattern. The Williamson-Hall (W-H) plot method were used to\nstudy the individual involvements of crystallite sizes and lattice strain on\nthe peak broadening of the NPs of ZCFO spinels. Whereas, particle size of the\nZCFO sample with x = 0.40 was estimated by high-resolution scanning electron\nmicroscopy micrographs",
        "positive": "Template induced precursor formation in heterogeneous nucleation --\n  Controlling polymorph selection and nucleation efficiency: We present an atomistic study of heterogeneous nucleation in Ni employing\ntransition path sampling, which reveals a template precursor-mediated mechanism\nof crystallization. Most notably, we find that the ability of tiny templates to\nmodify the structural features of the liquid and promote the formation of\nprecursor regions with enhanced bond-orientational order is key to determine\ntheir nucleation efficiency and the polymorphs that crystallize. Our results\nreveal an intrinsic link between liquid heterogeneity and the nucleating\nability of templates, which significantly advances our understanding towards\nthe control of nucleation efficiency and polymorph selection."
    },
    {
        "anchor": "Antiadiabatic View of Fast Environmental Effects on Optical Spectra: An antiadiabatic approach is proposed to model how the refractive index of\nthe surrounding medium affects optical spectra of molecular systems in\ncondensed phases. The approach solves some of the issues affecting current\nimplementations of continuum solvation models and more generally of effective\nmodels where a classical description is adopted for the molecular environment.",
        "positive": "Electronic cloaking of confined states in phosphorene junctions: We study the electronic transport of armchair and zigzag gated phosphorene\njunctions. We find confined states for both direction-dependent phosphorene\njunctions. In the case of armchair junctions confined states are reflected in\nthe transmission properties as Fabry-P\\'erot resonances at normal and oblique\nincidence. In the case of zigzag junctions confined states are invisible at\nnormal incidence, resulting in a null transmission. At oblique incidence\nFabry-P\\'erot resonances are presented in the transmission as in the case of\narmchair junctions. This invisibility or electronic cloaking is related to the\nhighly direction-dependent pseudospin texture of the charge carriers in\nphosphorene. Electronic cloaking is also manifested as a series of singular\npeaks in the conductance and as inverted peaks in the Seebeck coefficient. The\ncharacteristics of electronic cloaking are also susceptible to the modulation\nof the phosphorene bandgap and an external magnetic field. So, electronic\ncloaking in phosphorene junctions in principle could be tested through\ntransport, thermoelectric or magnetotransport measurements."
    },
    {
        "anchor": "Tunable band gaps in bilayer graphene-BN heterostructures: We investigate band-gap tuning of bilayer graphene between hexagonal boron\nnitride sheets, by external electric fields. Using density functional theory,\nwe show that the gap is continuously tunable from 0 to 0.2 eV, and is robust to\nstacking disorder. Moreover, boron nitride sheets do not alter the fundamental\nresponse from that of free-standing bilayer graphene, apart from additional\nscreening. The calculations suggest that the graphene-boron nitride\nheterostructures could provide a viable route to graphene-based electronic\ndevices.",
        "positive": "Bonding mechanisms in cold spray deposition of gas atomised and solution\n  heat-treated Al 6061 powder by EBSD: The heat-treatment of a number of gas atomised aluminium alloys prior to cold\nspraying recently showed that the resultant microstructural modification was\naccompanied by an improvement in deposition; however, the relationship between\nthe microstructural homogenisation occurring after recrystallisation and the\nincrease in deposition efficiency and particle-particle bonding had not been\ninvestigated. In this study, AL 6061 gas atomised feedstock powder, before and\nafter solution heat-treatment, was cold sprayed and these materials were\ncharaterised using electron backscatter diffraction. The solution heat-treated\nAl 6061 powder showed large stress-free grains as opposed to the as-atomised\nfeedstock powder which exhibited a homogeneous distribution of misorientation\nand lattice defects throughout the particles, whereas the coating produced from\nsolution heat-treated powder showed an accumulation of dislocations in the\ninterfacial zones. For the first time, a mechanism was proposed where this\nphenomenon was attributed to localised deformation of the heat-treated\nparticle's exterior due to the dissolution of precipitates in the intermetallic\nnetwork. The accumulation of dislocations in the interfacial area enhanced the\nrotation of subgrains to accomodate the plastic deformation, thus improving the\nparticle-particle bonding."
    },
    {
        "anchor": "Quantum criticality in a uniaxial organic ferroelectric: Tris-sarcosine calcium chloride (TSCC) is a highly uniaxial ferroelectric\nwith a Curie temperature of approximately 130K. By suppressing ferroelectricity\nwith bromine substitution on the chlorine sites, pure single crystals were\ntuned through a ferroelectric quantum phase transition. The resulting quantum\ncritical regime was investigated in detail - the first time for a uniaxial\nferroelectric and for an organic ferroelectric - and was found to persist up to\ntemperatures of at least 30K to 40K. The nature of long-range dipole\ninteractions in uniaxial materials, which lead to non-analytical terms in the\nfree-energy expansion in the polarization, predict a dielectric susceptibility\nvarying as $1/T^3$ close to the quantum critical point. Rather than this, we\nfind that the dielectric susceptibility varies as $1/T^2$ as expected and\nobserved in better known multi-axial systems. We explain this result by\nidentifying the ultra-weak nature of the dipoles in the TSCC family of\ncrystals. Interestingly we observe a shallow minimum in the inverse dielectric\nfunction at low temperatures close to the quantum critical point in\nparaelectric samples that may be attributed to the coupling of quantum\npolarization and strain fields. Finally we present results of the heat capacity\nand electro-caloric effect and explain how the time dependence of the\npolarization in ferroelectrics and paraelectrics should be considered when\nmaking quantitative estimates of temperature changes induced by applied\nelectric fields.",
        "positive": "The deffect effect on electronic conductance in binomially tailored\n  quantum wire: The paper considers the effect of the defects on the electronic transmission\nproperties in binomially tailored waveguide quantum wires, in which each Dirac\ndelta function potential strength have been weight on the binomial distribution\nlaw. We have assumed that a single free-electron channel is incident on the\nstructure and the scattering of electrons is solely from the geometric nature\nof the problem. We have used the transfer matrix method to study the electron\ntransmission. We found this novel structure has a good defect tolerance. We\nfound the structure tolerate up to in strength defect and in position defect\nfor the central Dirac delta function in the binomial distribution. Also, we\nfound this structure can tolerate both defect up to in strength and in position\ndislocation"
    },
    {
        "anchor": "Flatbands and Mechanical Deformation Effects in the Moir\u00e9 Superlattice\n  of MoS$_2$-WSe$_2$ Heterobilayers: It has recently been shown that quantum-confined states can appear in\nepitaxially grown van der Waals material heterobilayers without a rotational\nmisalignment ($\\theta=0^\\circ$), associated with flat bands in the Brillouin\nzone of the moir\\'e pattern formed due to the lattice mismatch of the two\nlayers. Peaks in the local density of states and confinement in a\nMoS$_2$/WSe$_2$ system was qualitatively described only considering local\nstacking arrangements, which cause band edge energies to vary spatially. In\nthis work, we report the presence of large in-plane strain variation across the\nmoir\\'e unit cell of a $\\theta=0^\\circ$ MoS$_2$/WSe$_2$ heterobilayer, and show\nthat inclusion of strain variation and out-of-plane displacement in density\nfunctional theory calculations greatly improves their agreement with the\nexperimental data. We further explore the role of twist-angle by showing\nexperimental data for a twisted MoS$_2$/WSe$_2$ heterobilayer structure with\ntwist angle of $\\theta=15^\\circ$, that exhibits a moir\\'e pattern but no\nconfinement.",
        "positive": "Microstructural, vibrational, dielectric and ferroelectric properties\n  correlation in hot-pressed PbMg1/3Nb2/3O3 ceramics: Microstrctural, vibrational, ferroelectric and dielectric properties\ninvestigation reveals non-stoichiometric chemical ordered regions (CORs) and\nrelaxor like dielectric characteristics in lead magnesium niobate (PMN)\nceramics uniaxially hot pressed (HP) at 800 oC to 1200 oC. Occurance of (1/2\n1/2 1/2) superlattice reflections along <111> in <110> zone axis SAED pattern\nas well as the presence of bright nano-meter regions in corresponding\ndark-field images in 800 oC hot pressed PMN demonstrates formation of the CORs\nas soon as perovskite phase is formed during calcination and remains unaffected\nwith HP sintering tempreature. Separation between two broad peaks of Nb-O-Nb\nstretching mode and the red-shift of O-B-O bending modes suggest an increase in\nthe polar nano-size regions. Grain size dependence of the em and shifting of\nthe Tm from 278 K to 263 K is explained by the core-shell model. Polarization\nswitching and impedance spectroscopy is observed to be consistent with the\ngrain size analysis."
    },
    {
        "anchor": "Crossover from meta-magnetic state to spin-glass behaviour upon\n  Ti-substitution for Mn in CuMn2O4: Tetragonal distorted spinel of CuMn2-xTixO4 (x = 0, 0.25 and 0.50) was\nprepared by solid state reaction method followed by neutron diffraction, FTIR\nspectroscopy, dielectric spectroscopy and magnetization measurements. The\nneutron diffraction and FTIR spectroscopy provide the information regarding\nphase formation. But, the magnetic susceptibility clearly shows the\nferri-magnetic order below 76K associated with meta-magnetic state which turns\nto spin-glass behaviour upon Ti-substitution for Mn in CuMn2O4. In addition,\nthe room temperature M(H) of all the spinels are described by the Arrott's plot\nfor weak ferromagnetism. Further, the room temperature dielectric measurement\nprovides the electronic property of CuMn2O4 dominated by grain boundary effect\nthat is significantly increased upon Ti-substitution for Mn in CuMn2O4.",
        "positive": "Accurate Machine Learning Predictions of Coercivity in High-Performance\n  Permanent Magnets: Increased demand for high-performance permanent magnets in the electric\nvehicle and wind turbine industries has prompted the search for cost-effective\nalternatives. Nevertheless, the discovery of new magnetic materials with the\ndesired intrinsic and extrinsic permanent magnet properties presents a\nsignificant challenge. Traditional density functional theory (DFT) accurately\npredicts intrinsic permanent magnet properties such as magnetic moments,\nmagneto-crystalline anisotropy constants, and exchange interactions. However,\nit cannot compute extrinsic macroscopic properties, such as coercivity ($H_c$),\nwhich are influenced by factors like microscopic defects and internal grain\nstructures. Although micromagnetic simulation helps compute $H_c$, it\noverestimates the values almost by an order of magnitude due to Brown's\nparadox. To circumvent these limitations, we employ machine learning (ML)\nmethods in an extensive database obtained from experiments, DFT calculations,\nand micromagnetic modeling. Our novel ML approach is computationally much\nfaster than the micromagnetic simulation program, the mumax$^3$. We\nsuccessfully utilize it to predict $H_c$ values for materials like cerium-doped\n$\\mathrm{Nd}_2\\mathrm{Fe}_{14}\\mathrm{B}$, and subsequently compare the\npredicted values with experimental results. Remarkably, our ML model accurately\nidentifies uniaxial magnetic anisotropy as the primary contributor to $H_c$.\nWith DFT calculations, we predict the Nd-site dependent magnetic anisotropy\nbehavior in $\\mathrm{Nd}_2\\mathrm{Fe}_{14}\\mathrm{B}$, confirming $4f$-site\nplanar and $4g$-site uniaxial to crystalline $c$-direction in good agreement\nwith experiment. The Green's function atomic sphere approximation calculated a\nCurie temperature ($T_{\\rm C}$) for $\\mathrm{Nd}_2\\mathrm{Fe}_{14}\\mathrm{B}$\nthat also agrees well with experiment."
    },
    {
        "anchor": "Enhanced interfacial thermal conductance in functionalized Boron\n  Nitride/Polylactic acid nanocomposite: A molecular dynamics study: The relatively low thermal conductivity of biodegradable polylactic acid\n(PLA) has limited its applications in various fields. To address this issue,\nthe incorporation of nanofillers, such as boron nitride nanosheets (BNNSs), has\nemerged as an effective method to enhance PLA's thermal properties. However,\nthe thermal conduction of polymer-based nanocomposites is strongly influenced\nby interfacial thermal resistance. In this study, we investigate the impact of\npristine and surface-treated BNNSs on the thermal behavior of PLA using\nmolecular dynamics simulations. To enhance interfacial interactions and reduce\nchain mobility during heat transfer, we chemically modify the surface of BNNSs\nby introducing three different functional groups (NH2, OH, and COOH) with\nvarying polarities. Our findings suggest that oxygen-containing groups, namely\nOH and COOH, exhibit stronger interfacial interactions compared to the other\ncases. We also systematically apply different percentages of these functional\ngroups (i.e., 2.5, 5, and 7.5) and observe that a higher number of functional\ngroups leads to a greater improvement in interfacial thermal transport,\nattributed to the enhanced phonon coupling effect. To complete the discussion,\nwe thoroughly study the influence of random and agglomerated patterns of\nfunctional groups distribution.",
        "positive": "Tailoring electronic and elastic properties by varying composition of\n  the CuGa1-xAlxS2 chalcopyrite semiconductor: Influence of composition and external hydrostatic pressure on the structural,\nelectronic, and optical properties of the CuGa1-xAlxS2 (x=0, 0.25, 0.5, 0.75,\n1.0) chalcopyrite semiconductor was analyzed by means of the first-principles\ncalculations. Dielectric functions and optical absorption spectra were\ncalculated for all considered aluminum concentrations. The pressure\ncoefficients of the calculated band gaps and position of the lowest in energy\nabsorption peaks were extracted from the calculated results. One of the main\nresults is that substitution of 25% of gallium by aluminum (thus forming the\nCuGa0.75Al0.25S2 semiconductor) increases absorption in the visible part of the\nsolar spectrum by about 6%, which can be important for the solar cell\napplications."
    },
    {
        "anchor": "Extraordinary magnetization behavior of single crystalline\n  TbFe_4.4Al_7.6: We report the observation of a field-induced transformation from the\neasy-plane antiferromagnetic structure to the easy-axis ferrimagnetic structure\nin a single crystal of TbFe_4.4Al_7.6 (tetragonal ThMn_12 structure) at 5 K.\nSuch a field-induced, irreversible transition has been identified for the first\ntime. This transition is accompanied by a giant orthorhombic distortion:\nepsilon_aa = - epsilon_bb ~ 3.5x10^-4 that is associated with a magnetic\nhardness (mu_0H_C ~ 3 T) that is unprecedented in this category of materials.",
        "positive": "Aerodynamical Effects in Snow Crystal Growth: We review several aspects of aerodynamics that affect the growth, morphology,\nand symmetry of snow crystals. We derive quantitative estimates for\naerodynamical forces that orient falling snow crystals, estimate how air flow\naround snow crystals affects their growth rates (the ventilation effect), and\nexamine how the combination of orientation and growth modification can\nstabilize or destabilize different growth behaviors. Special attention is given\nto the formation of triangular snow crystals, since it appears that\naerodynamical effects are responsible for producing this unusual morphology,\nboth in nature and in the laboratory."
    },
    {
        "anchor": "Current-Induced Magnetization Control in Insulating Ferrimagnetic\n  Garnets: The research into insulating ferrimagnetic garnets has gained enormous\nmomentum in the past decade. This is partly due to the improvement in the\ntechniques to grow high-quality ultrathin films with desirable properties and\nthe advances in understanding the spin transport within the ferrimagnetic\ngarnets and through their interfaces with conducting materials. In recent\nyears, we have seen remarkable progress in controlling the magnetization state\nof ferrimagnetic garnets by electrical means in suitable heterostructures and\ndevice architectures. These advances have readily placed ferrimagnetic garnets\nin a favorable position for the future development of insulating spintronic\nconcepts. The purpose of this article is to review recent experimental results\nof the current-induced magnetization control and associated phenomena in\nferrimagnetic garnets, as well as to discuss future directions in this rapidly\nevolving area of spintronics.",
        "positive": "Evidence for anisotropic dielectric properties of monoclinic hafnia\n  using high-resolution TEM valence electron energy-loss spectroscopy and ab\n  initio time-dependent density-functional theory: The effect of nanocrystal orientation on the energy loss spectra of\nmonoclinic hafnia (m-HfO$_2$) is measured by high resolution transmission\nelectron microscopy (HRTEM) and valence energy loss spectroscopy (VEELS) on\nhigh quality samples. For the same momentum-transfer directions, the dielectric\nproperties are also calculated ab initio by time-dependent density-functional\ntheory (TDDFT). Experiments and simulations evidence anisotropy in the\ndielectric properties of m-HfO$_2$, most notably with the direction-dependent\noscillator strength of the main bulk plasmon. The anisotropic nature of\nm-HfO$_2$ may contribute to the differences among VEELS spectra reported in\nliterature. The good agreement between the complex dielectric permittivity\nextracted from VEELS with nanometer spatial resolution, TDDFT modeling, and\npast literature demonstrates that the present HRTEM-VEELS device-oriented\nmethodology is a possible solution to the difficult nanocharacterization\nchallenges given in the International Technology Roadmap for Semiconductors."
    },
    {
        "anchor": "A theoretical and semiemprical correction to the long-range dispersion\n  power law of stretched graphite: In recent years intercalated and pillared graphitic systems have come under\nincreasing scrutiny because of their potential for modern energy technologies.\nWhile traditional \\emph{ab initio} methods such as the LDA give accurate\ngeometries for graphite they are poorer at predicting physicial properties such\nas cohesive energies and elastic constants perpendicular to the layers because\nof the strong dependence on long-range dispersion forces. `Stretching' the\nlayers via pillars or intercalation further highlights these weaknesses. We use\nthe ideas developed by [J. F. Dobson et al, Phys. Rev. Lett. {\\bf 96}, 073201\n(2006)] as a starting point to show that the asymptotic $C_3 D^{-3}$ dependence\nof the cohesive energy on layer spacing $D$ in bigraphene is universal to all\ngraphitic systems with evenly spaced layers. At spacings appropriate to\nintercalates, this differs from and begins to dominate the $C_4 D^{-4}$ power\nlaw for dispersion that has been widely used previously. The corrected power\nlaw (and a calculated $C_3$ coefficient) is then unsuccesfully employed in the\nsemiempirical approach of [M. Hasegawa and K. Nishidate, Phys. Rev. B {\\bf 70},\n205431 (2004)] (HN). A modified, physicially motivated semiempirical method\nincluding some $C_4 D^{-4}$ effects allows the HN method to be used\nsuccessfully and gives an absolute increase of about $2-3%$ to the predicted\ncohesive energy, while still maintaining the correct $C_3 D^{-3}$ asymptotics.",
        "positive": "Dielectric Screening by 2D Substrates: Two-dimensional (2D) materials are increasingly being used as active\ncomponents in nanoscale devices. Many interesting properties of 2D materials\nstem from the reduced and highly non-local electronic screening in two\ndimensions. While electronic screening within 2D materials has been studied\nextensively, the question still remains of how 2D substrates screen charge\nperturbations or electronic excitations adjacent to them. Thickness-dependent\ndielectric screening properties have recently been studied using electrostatic\nforce microscopy (EFM) experiments. However, it was suggested that some of the\nthickness-dependent trends were due to extrinsic effects. Similarly, Kelvin\nprobe measurements (KPM) indicate that charge fluctuations are reduced when BN\nslabs are placed on SiO$_2$, but it is unclear if this effect is due to\nintrinsic screening from BN. In this work, we use first principles calculations\nto study the fully non-local dielectric screening properties of 2D material\nsubstrates. Our simulations give results in good qualitative agreement with\nthose from EFM experiments, for hexagonal boron nitride (BN), graphene and\nMoS$_2$, indicating that the experimentally observed thickness-dependent\nscreening effects are intrinsic to the 2D materials. We further investigate\nexplicitly the role of BN in lowering charge potential fluctuations arising\nfrom charge impurities on an underlying SiO$_2$ substrate, as observed in the\nKPM experiments. 2D material substrates can also dramatically change the\nHOMO-LUMO gaps of adsorbates, especially for small molecules, such as benzene.\nWe propose a reliable and very quick method to predict the HOMO-LUMO gap of\nsmall physisorbed molecules on 2D and 3D substrates, using only the band gap of\nthe substrate and the gas phase gap of the molecule."
    },
    {
        "anchor": "A simple model for predicting crystallization and melting temperatures,\n  and its implications for phase transitions in confined volumes: We present a simple unifying model for crystallization and melting\ntemperatures by showing that homogeneous nucleation and phase transformations\ndriven by thickening of pre-existing surface layers are limiting conditions of\nthe more general heterogeneous nucleation case. Furthermore, to a first\napproximation all these processes can be described by an extended classical\nnucleation theory. The model can also be applied to phase transition\ntemperatures in confined volumes, provided reliable values for the interfacial\ntensions within the systems are determinable. The expected melting and\ncrystallization temperature for any transformation pathway can then be\npredicted.",
        "positive": "Design of a low-velocity impact framework for evaluating space-grade\n  materials: Material deformation and failure under impact loading is a subject of active\ninvestigation in space science and often requires very specialized equipment\nfor testing. In this work, we present the design, operational analysis and\napplication of a low-velocity ($\\sim 100$ m/s) projectile impact framework for\nevaluating the deformation and failure of space-grade materials. The system is\ndesigned to be modular and easily adaptable to various test geometries, while\nenabling accurate quantitative evaluation of plastic flow. Using coupled\nnumerical methods and experimental techniques, we first establish an operating\nprocedure for the system. Following this, its performance in two complementary\nimpact configurations is demonstrated using numerical and experimental\nanalysis. In the first, a Taylor impact test is performed for predicting the\ndeformed shape of a cylindrical projectile impinging on a rigid substrate. In\nthe second, deformation of a plate struck by a rigid projectile is evaluated.\nIn both cases, physics-based models are used to interpret the resulting fields.\nWe present a discussion of how the system may be used both for material\nproperty estimation (e.g., dynamic yield strength) as well as for failure\nevaluation (e.g., perforation and fracture) in the same projectile impact\nconfiguration."
    },
    {
        "anchor": "Coherent and incoherent excitation pathways in time-resolved\n  photoemission orbital tomography of CuPc/Cu(001)-2O: Time-resolved photoemission orbital tomography (tr-POT) offers unique\npossibilities for tracing molecular electron dynamics. The recorded\npump-induced changes of the angle-resolved photoemission intensities allow to\ncharacterize unoccupied molecular states in momentum space and to deduce the\nincoherent temporal evolution of their population. Here, we show for the\nexample of CuPc/Cu(001)-2O that the method also gives access to the coherent\nregime and that different excitation pathways can be disentangled by a careful\nanalysis of the time-dependent change of the photoemission momentum pattern. In\nparticular, we demonstrate by varying photon energy and polarization of the\npump light, how the incoherent temporal evolution of the LUMO distribution can\nbe distinguished from coherent contributions of the projected HOMO. Moreover,\nwe report the selective excitation of molecules with a specific orientation at\nnormal incidence by aligning the electric field of the pump light along the\nmolecular axis.",
        "positive": "Resolving Local Electrochemistry at the Nanoscale via Electrochemical\n  Strain Microscopy: Modeling and Experiments: Electrochemistry is the underlying mechanism in a variety of energy\nconversion and storage systems, and it is well known that the composition,\nstructure, and properties of electrochemical materials near active interfaces\noften deviates substantially and inhomogeneously from the bulk properties. A\nuniversal challenge facing the development of electrochemical systems is our\nlack of understanding of physical and chemical rates at local length scales,\nand the recently developed electrochemical strain microscopy (ESM) provides a\npromising method to probe crucial local information regarding the underlying\nelectrochemical mechanisms. Here we develop a computational model that couples\nmechanics and electrochemistry relevant for ESM experiments, with the goal to\nenable quantitative analysis of electrochemical processes underneath a charged\nscanning probe. We show that the model captures the essence of a number of\ndifferent ESM experiments, making it possible to de-convolute local ionic\nconcentration and diffusivity via combined ESM mapping, spectroscopy, and\nrelaxation studies. Through the combination of ESM experiments and\ncomputations, it is thus possible to obtain deep insight into the local\nelectrochemistry at the nanoscale."
    },
    {
        "anchor": "Determining the range of magnetic interactions from the relations\n  between magnon eigenvalues at high-symmetry k points: Magnetic exchange interactions (MEIs) define networks of coupled magnetic\nmoments and lead to a surprisingly rich variety of their magnetic properties.\nTypically MEIs can be estimated by fitting experimental results. But how many\nMEIs need to be included in the fitting process for a material is not clear a\npriori, which limits the quality of results obtained by these conventional\nmethods. In this paper, based on linear spin-wave theory but without performing\nmatrix diagonalization, we show that for a general quadratic spin Hamiltonian,\nthere is a simple relation between the Fourier transform of MEIs and the sum of\nsquare of magnon energies (SSME). We further show that according to the\nreal-space distance range within which MEIs are considered relevant, one can\nobtain the corresponding relationships between SSME in momentum space. We also\ndevelop a theoretical tool for tabulating the rule about SSME. By directly\nutilizing these characteristics and the experimental magnon energies at only a\nfew high-symmetry k points in the Brillouin zone, one can obtain strong\nconstraints about the range of exchange path beyond which MEIs can be safely\nneglected. Our methodology is also general applicable for other Hamiltonian\nwith quadratic Fermi or Boson operators.",
        "positive": "Influence of structural defects on the magnetocaloric effect in the\n  vicinity of the first order magnetic transition in Fe(50.4)Rh(49.6): The large magnetocaloric effect (MCE), which accompanies the first order\nferromagnetic/anti-ferromagnetic transition in CsCl-ordered Fe-Rh alloys, has\nbeen investigated by measurements in slowly cycled magnetic fields of up to 2 T\nin magnitude for a range of temperatures, 300K < T < 350K. A bulk sample with\ncomposition Fe(50.4)Rh(49.6) was used and the results were compared with those\nproduced by the ab-initio density functional theory-based disordered local\nmoment (DLM) theory of the MCE. The measurements revealed an irreversibility\neffect in which the temperature of the material did not return to its initial\nvalue following several cycles of the magnetic field. These observations were\nexplained in the framework of the ab-initio theory for the first order\ntransition in which the consequences of the incomplete long range compositional\norder and small compositional inhomogeneities of the sample were included. The\nmean value of the long range order parameter S used in the theoretical work was\n0.985, close to the value obtained experimentally from XRD measurements. The\nsample inhomogeneities were modeled by regions in the sample having a\ndistribution of S values with narrow half-width 0.004 about the mean value. The\ninfluence of such compositional disorder on both the transition temperature\n(323.5 K) and MCE adiabatic temperature change (delT = 7.5 K) was also studied."
    },
    {
        "anchor": "Neutron diffraction evidence for kinetic arrest of the first-order\n  austenite to martensite transition in Ni37Co11Mn42.5Sn9.5: Neutron diffraction measurements, performed in presence of an external\nmagnetic field, have been used to show structural evidence for the kinetic\narrest of the first-order phase transition from the high temperature austenite\nphase to the low temperature martensite phase in the magnetic shape memory\nalloy Ni37Co11Mn42.5Sn9.5 and the formation of a glass-like arrested state\n(GLAS). The CHUF (cooling and heating under unequal fields) protocol has been\nused to establish phase coexistence of metastable and equilibrium states of\nGLAS in the neutron diffraction patterns. We also explore the field-temperature\n(H,T) phase diagram for this composition which depicts the kinetic arrest line\nTK(H). TK is seen to increase as H increases.",
        "positive": "Analogy between dielectric relaxation and dielectric mixtures:\n  Application of the spectral density representation: The spectral representation is an effecient tool to explore electrical\nproperties of material mixtures. It separates the contributions of geometrical\ntopology and intrinsic properties of the constituents in the system. The aim of\nthis paper is to derive an expression for the spectral density representation,\nwhich favors dielectric relaxation phenomenon. This unfamiliar form is distinct\nin a way that the existing dielectric relaxation models and data analysis tools\ncan be employed for extracting the spectral density function of a given system."
    },
    {
        "anchor": "Pressure-induced softening in bulk modulus due to magneto-elastic\n  coupling in Nd$_2$CoFeO$_6$ double Perovskite: Double perovskite oxide materials have garnered tremendous interest due to\ntheir strong spin-lattice-charge coupling. Interesting in their own right,\nrare-earth-based DPOs have yet to be subjected to high-pressure studies. In\nthis paper, we have investigated the structural response of Nd$_2$CoFeO$_6$ to\npressure by XRD and Raman spectroscopic measurements. From XRD data, we have\nobserved pressure-induced structural transition from the orthorhombic phase to\nthe monoclinic phase at about 13.8~\\si{\\giga\\pascal}. An anomalous increase in\ncompressibility at a much lower pressure($\\sim$1.1~\\si{\\giga\\pascal}) is seen\nwhere no structural transition occurs. At about the same pressure, a sudden\ndrop in the slope of Raman modes is observed. Further investigation at low\ntemperatures reveals that the B$_g$ Raman mode is strongly affected by magnetic\ninteractions. Additional high-pressure Raman experiments with the application\nof a magnetic field indicated that the mentioned anomaly around\n1.1~\\si{\\giga\\pascal} can be explained by a high-spin to low-spin transition of\nCo$^{3+}$.",
        "positive": "Evidence for an Excitonic Insulator State in Ta$_2$Pd$_3$Te$_5$: The excitonic insulator (EI) is an exotic ground state of narrow-gap\nsemiconductors and semimetals arising from spontaneous condensation of\nelectron-hole pairs bound by attractive Coulomb interaction. Despite research\non EIs dating back to half a century ago, their existence in real materials\nremains a subject of ongoing debate. In this study, through systematic\nexperimental and theoretical investigations, we provide evidence for the\nexistence of an EI ground state in a van der Waals compound Ta$_2$Pd$_3$Te$_5$.\nDensity-functional-theory calculations suggest that it is a semimetal with a\nsmall band overlap, whereas various experiments exhibit an insulating ground\nstate with a clear band gap. Upon incorporating electron-hole Coulomb\ninteraction into our calculations, we obtain an EI phase where the electronic\nsymmetry breaking opens a many-body gap. Angle-resolved photoemission\nspectroscopy measurements exhibit that the band gap is closed with a\nsignificant change in the dispersions as the number of thermally excited charge\ncarriers becomes sufficiently large in both equilibrium and nonequilibrium\nstates. Structural measurements reveal a slight breaking of crystal symmetry\nwith exceptionally small lattice distortion in the insulating state, which\ncannot account for the significant gap opening. Therefore, we attribute the\ninsulating ground state with a gap opening in Ta$_2$Pd$_3$Te$_5$ to exciton\ncondensation, where the coupling to the symmetry-breaking electronic state\ninduces a subtle change in the crystal structure."
    },
    {
        "anchor": "Resistive Switching Characteristics of Al/Si3N4/p-Si MIS-Based Resistive\n  Switching Memory Devices: In this study, we proposed and demonstrated a self-rectifying property of\nsilicon nitride (Si3N4)-based resistive random access memory device by\nemploying p-type silicon (p-Si) as bottom electrode. The RRAM devices consisted\nof Al/Si3N4/p-Si are fabricated by a low presure chemical vapor deposition and\nexhibited an intrinsic diode property with non-linear current-voltage (I-V)\nbehavior. In addition, compared to conventional metal/insulator/metal (MIM)\nstructure of Al/Si3N4/Ti RRAM cells, operating current in whole bias regions\nfor proposed metal/insulator/semiconductor (MIS) cells has been dramatically\nlowered because introduced p-Si bottom electrode efficiently suppresses the\ncurrent in both low and high resistive states. As a result, the results mean\nthat by employing p-Si as bottom electrode the Si3N4-based RRAM cells can be\napplied to selector-free RRAM cells.",
        "positive": "Suppressing spin relaxation in silicon: Uniaxial compressive strain along the [001] direction strongly suppresses the\nspin relaxation in silicon. When the strain level is large enough so that\nelectrons are redistributed only in the two valleys along the strain axis, the\ndominant scattering mechanisms are quenched and electrons mainly experience\nintra-axis scattering processes (intravalley or intervalley scattering within\nvalleys on the same crystal axis). We first derive the spin-flip matrix\nelements due to intra-axis electron scattering off impurities, and then provide\na comprehensive model of the spin relaxation time due to all possible\ninteractions of conduction-band electrons with impurities and phonons. We\npredict nearly three orders of magnitude improvement in the spin relaxation\ntime of $\\sim10^{19}\\text{cm}^{-3}$ antimony-doped silicon (Si:Sb) at low\ntemperatures."
    },
    {
        "anchor": "Prediction of the bias voltage dependent magnetic contrast in\n  spin-polarized scanning tunneling microscopy: This work is concerned with the theoretical description of the contrast,\ni.e., the apparent height difference between two lateral surface positions on\nconstant current spin-polarized scanning tunneling microscopy (SP-STM) images.\nWe propose a method to predict the bias voltage dependent magnetic contrast\nfrom single point tunneling current or differential conductance measurements,\nwithout the need of scanning large areas of the surface. Depending on the\nnumber of single point measurements, the bias positions of magnetic contrast\nreversals and of the maximally achievable magnetic contrast can be determined.\nWe validate this proposal by simulating SP-STM images on a complex magnetic\nsurface employing a recently developed approach based on atomic superposition.\nFurthermore, we show evidence that the tip electronic structure and magnetic\norientation have a major effect on the magnetic contrast. Our theoretical\nprediction is expected to inspire experimentalists to considerably reduce\nmeasurement efforts for determining the bias dependent magnetic contrast on\nmagnetic surfaces.",
        "positive": "First principles investigation of structural, electronic and optical\n  properties of MgRh intermetallic compound: The structural electronic and optical properties of intermetallic compound\nMgRh were investigated by using the ab-initio technique from CASTEP code. In\nthis study we have carried out the pseudo-potential plane-wave (PP-PW) method\nbased on the density functional theory (DFT), within the generalized gradient\napproximation (GGA). Our calculated structural parameters and corresponding\ngraphical values fit with other previous available experimental data and other\ntheoretical observations. The calculated electronic band structure reveals\nmetallic conductivity and the major contribution comes from Rh-d states.\nComparison between our investigated properties and experimental data shows good\nagreement. The optical functions (dielectric functions, refractive index,\nabsorption spectrum, conductivity, energy loss spectrum and reflectivity) have\nbeen calculated and discussed. This is the first quantitative prediction of the\nelectronic and optical properties of intermetallic compound MgRh alloy, since\nit has not been reported yet. The calculated optical functions reveal that the\nreflectivity is high in the ultraviolet region up to 73 eV for MgRh, showing\nthis to be promising coating materials."
    },
    {
        "anchor": "A nonequilibrium Green's function study of thermoelectric properties in\n  single-walled carbon nanotubes: The phonon and electron transport in single-walled carbon nanotubes (SWCNT)\nare investigated using the nonequilibrium Green's function approach. In zigzag\nSWCNT ($n$, 0) with $mod(n,3)\\not=0$, the thermal conductance is mainly\nattributed to the phonon transport, while the electron only has few percentage\ncontribution. The maximum value of the figure of merit ($ZT$) is about 0.2 in\nthis type of SWCNT. The $ZT$ is considerably larger in narrower SWCNT because\nof enhanced Seebeck coefficient. $ZT$ is smaller in the armchair SWCNT, where\nSeebeck coefficient is small due to zero band gap. It is found that the cluster\nisotopic doping can reduce the phonon thermal conductance obviously and enhance\nthe value of $ZT$. The uniaxial elongation and compress strain depresses\nphonons in whole frequency region, leading to the reduction of the phonon\nthermal conductance in whole temperature range. Interestingly, the elongation\nstrain can affect the phonon transport more seriously than the compress strain,\nbecause the high frequency $G$ mode is completely filtered out under elongation\nstrain $\\epsilon >0.05$. The strain also has important effect on the subband\nedges of the electron band structure by smoothing the steps in the electron\ntransmission function. The $ZT$ is decreased by strain as the reduction in the\nelectronic conductance overcomes the reduction in the thermal conductance.",
        "positive": "Phase Stability of Hexagonal/cubic Boron Nitride Nanocomposites: Boron nitride (BN) is an exceptional material and among its polymorphs,\ntwo-dimensional (2D) hexagonal and three-dimensional (3D) cubic BN (h-BN and\nc-BN) phases are most common. The phase stability regimes of these BN phases\nare still under debate and phase transformations of h-BN/c-BN remain a topic of\ninterest. Here, we investigate the phase stability of 2D/3D h-BN/c-BN\nnanocomposites and show that the co-existence of two phases can lead to strong\nnon-linear optical properties and low thermal conductivity at room temperature.\nFurthermore, spark-plasma sintering of the nanocomposite shows complete phase\ntransformation to 2D h-BN with improved crystalline quality, where 3D c-BN\ngrain sizes governs the nucleation and growth kinetics. Our demonstration might\nbe insightful in phase engineering of BN polymorphs based nanocomposites with\ndesirable properties for optoelectronics and thermal energy management\napplications."
    },
    {
        "anchor": "Four-coloured Spin-wave Excitations in Multiferroic Materials: The optical magnetoelectric effect, which is an inherent attribute of the\nspin excitations in multiferroics, drastically changes their optical properties\ncompared to conventional materials where light-matter interaction is expressed\nonly by the dielectric permittivity and magnetic permeability. Our polarized\nabsorption experiments performed on multiferroic Ca2CoSi2O7 and Ba2CoGe2O7 in\nthe THz spectral range demonstrate that such magnetoeletric spin excitations\nshow quadrochroism, i.e. they have different colours for all the four\ncombinations of the two propagation directions (forward or backward) and the\ntwo orthogonal polarizations of a light beam. We found that quadrochroism can\ngive rise to peculiar optical properties, such as one-way transparency and\nzero-reflection of these excitations, which can open a new horizon in\nphotonics. One-way transparency is also related to the static magnetoelectric\nphenomena, hence, these optical studies can provide guidelines for the\nsystematic synthesis of new materials with large dc magnetoelectric effect.",
        "positive": "Polar magneto-optical Kerr effect in antiferromagnetic M$_2$As (M=Cr,\n  Mn, Fe) under an external magnetic field: Antiferromagnetic metals attract tremendous interest for memory applications\ndue to their expected fast response dynamics in the terahertz frequency regime.\nReading from and writing information into these materials is not easily\nachievable using magnetic fields, due to weak high-order magneto-optical\nsignals and robustness of the magnetic structure against external magnetic\nfields. Polarized electromagnetic radiation is a promising alternative for\nprobing their response, however, when ideal antiferromagnetic symmetry is\npresent, this response vanishes. Hence, in this work we combine\nfirst-principles simulations with measurements of the polar magneto-optical\nKerr effect under external magnetic fields, to study magneto-optical response\nof antiferromagnetic M$_2$As (M=Cr, Mn, and Fe). We devise a computational\nscheme to compute the magnetic susceptibility from total-energy changes using\nconstraints on magnetic-moment tilting. Our predictions of the spectral\ndependence of polar magneto-optical Kerr rotation and ellipticity allow us to\nattribute these effects to breaking of the magnetic symmetry. We show that\ntilting affects the exchange interaction, while the spin-orbit interaction\nremains unaffected as the tilting angle changes. Our work provides\nunderstanding of the polar magneto-optical Kerr effect on a band structure\nlevel and underscores the importance of the magnetic susceptibility when\nsearching for materials with large magneto-optical response."
    },
    {
        "anchor": "Chemical profiles of the oxides on tantalum in state of the art\n  superconducting circuits: Over the past decades, superconducting qubits have emerged as one of the\nleading hardware platforms for realizing a quantum processor. Consequently,\nresearchers have made significant effort to understand the loss channels that\nlimit the coherence times of superconducting qubits. A major source of loss has\nbeen attributed to two level systems that are present at the material\ninterfaces. We recently showed that replacing the metal in the capacitor of a\ntransmon with tantalum yields record relaxation and coherence times for\nsuperconducting qubits, motivating a detailed study of the tantalum surface. In\nthis work, we study the chemical profile of the surface of tantalum films grown\non c-plane sapphire using variable energy X-ray photoelectron spectroscopy\n(VEXPS). We identify the different oxidation states of tantalum that are\npresent in the native oxide resulting from exposure to air, and we measure\ntheir distribution through the depth of the film. Furthermore, we show how the\nvolume and depth distribution of these tantalum oxidation states can be altered\nby various chemical treatments. By correlating these measurements with detailed\nmeasurements of quantum devices, we can improve our understanding of the\nmicroscopic device losses.",
        "positive": "Statistical properties of microcracking in polyurethane foams under\n  tensile test, influence of temperature and density: We report tensile failure experiments on polyurethane (PU) foams. Experiments\nhave been performed by imposing a constant strain rate. We work on\nheterogeneous materials for whom the failure does not occur suddenly and can\ndevelop as a multistep process through a succession of microcracks that end at\npores. The acoustic energy and the waiting times between acoustic events follow\npower-law distributions. This remains true while the foam density is varied.\nHowever, experiments at low temperatures (PU foams more brittle) have not\nyielded power-laws for the waiting times. The cumulative acoustic energy has no\npower law divergence at the proximity of the failure point which is\nqualitatively in agreement with other experiments done at imposed strain. We\nnotice a plateau in cumulative acoustic energy that seems to occur when a\nsingle crack starts to propagate."
    },
    {
        "anchor": "On the role of physisorption states in molecular scattering: A\n  semi-local density-functional theory study on O2/Ag(111): We simulate the scattering of O$_2$ from Ag(111) with classical dynamics\nsimulations performed on a six-dimensional potential energy surface calculated\nwithin semi-local density-functional theory (DFT). The enigmatic experimental\ntrends that originally required the conjecture of two types of repulsive walls,\narising from a physisorption and chemisorption part of the interaction\npotential, are fully reproduced. Given the inadequate description of the\nphysisorption properties in semi-local DFT, our work casts severe doubts on the\nprevalent notion to use molecular scattering data as indirect evidence for the\nexistence of such states.",
        "positive": "Comparative study of specific heat measurements in LaMnO3,\n  La1.35Sr1.65Mn2O7, La1.5Sr0.5NiO4 and La1.5Sr0.5CoO4: We present the temperature dependence of the specific heat, without external\nmagnetic field and with H= 9 T, for LaMnO3, La1.35Sr1.65Mn2O7, La1.5Sr0.5NiO4\nand La1.5Sr0.5CoO4 single crystals. We found that spin-wave excitations in the\nferromagnetic and bilayer-structure La1.35Sr1.65Mn2O7 were suppressed by the 9\nT magnetic field. On the other hand, the external magnetic field had no effect\nin the specific heat of the other three antiferromagnetic samples. Also, the\nelectronic part of the interactions were removed at very low temperatures in\nthe La1.5Sr0.5NiO4 single crystal, even with a zero applied magnetic field.\nBelow 4 K, we found that the specific heat data for La1.35Sr1.65Mn2O7 and\nLa1.5Sr0.5NiO4 crystals could be fitted to an exponential decay law. Detailed\nmagnetization measurements in this low temperature interval showed the\nexistence of a peak close to 2 K. Both results, magnetizations and specific\nheat suggest the existence of an anisotropy gap in the energy spectrum of\nLa1.35Sr1.65Mn2O7 and La1.5Sr0.5NiO4 compounds."
    },
    {
        "anchor": "Where does the spin angular momentum go in laser induced\n  demagnetisation?: The dynamics of ultrafast demagnetisation in 3$d$ magnets is complicated by\nthe presence of both spin ${\\v S}$ and orbital ${\\v L}$ angular momentum, with\nthe microscopic mechanism by which the magnetic moment is redistributed to the\nlattice, and at what time scales, yet to be resolved. Employing\nstate-of-the-art time dependent density function theory we disentangle the\ndynamics of these two momenta. Utilising ultra short (5~fs) pulses that\nseparate spin-orbit (SO) and direct optical excitation time scales, we\ndemonstrate a two-step microscopic mechanism: (i) an initial loss of ${\\v L}$\ndue to laser excitation, followed post pulse by (ii) an increase of ${\\v L}$ as\n${\\v S}$ transfers to ${\\v L}$ during subsequent ($> 15$~fs) SO induced\nspin-flip demagnetisation. We also show that to see an unambiguous transfer of\n${\\v S}$ to ${\\v L}$ a short pulse is required.",
        "positive": "Phase Stability in Ferroelectric Bismuth Titanate: A First Principles\n  Study: Experimental data on the structure of ferroelectric oxide Bismuth Titanate\nsuggests two different kinds of structures i.e. orthorhombic and monoclinic. We\nhave performed density functional theory (DFT) based first principle\ncalculations to determine the ground state structure of bismuth titanate, based\non experimentally observed monoclinic and orthorhombic phases of Bi4Ti3O12.\nBoth of these phases are optimized to zero pressure and lattice parameters were\ndetermined as a = 5.4370 Ang, b = 5.4260 Ang, c = 32.6833 Ang and Z = 4 for\nstructure with space group B2cb and a = 5.4289 Ang, b = 5.4077 Ang, c = 32.8762\nAng, b = 90.08 deg and Z = 4 for the structure with space group B1a1 . Static\nand dynamic calculations show that the monoclinic structure with the space\ngroup B1a1 is the ground state structure. It is noted that small difference in\nthe energies of both structures could be a factor behind experimental\nobservation of either of the structure."
    },
    {
        "anchor": "Magnetic fingerprint in a ferromagnetic wire: Spin torque diode effect\n  and induction of the DC voltage spectrum inherent in the wire under\n  application for RF current: We report the rectifying effect of a constant-wave radio frequency (RF)\ncurrent by a magnetic domain wall (DW) on a single-layered ferromagnetic wire.\nA direct-current (DC) voltage is generated by the spin torque diode effect,\nwhich is a consequence of magnetoresistance oscillation due to the resonant\nspin wave excitation induced by the spin-polarized RF current. The DC voltage\nspectrum strongly depends on the internal spin structure in the DW, which\ncorresponds to the magnetic fingerprint of the spin structure in the\nferromagnetic wire.",
        "positive": "How to enhance anomalous Hall effects in magnetic Weyl semimetal\n  Co$_3$Sn$_2$S$_2$?: Large spin-orbit coupling, kagome lattice, nontrivial topological band\nstructure with inverted bands anti-crossings, and Weyl nodes are essential\ningredients, ideally required to obtain maximal anomalous Hall effect (AHE) are\nsimultaneously present in Co$_3$Sn$_2$S$_2$. It is a leading platform to show\nlarge intrinsic anomalous Hall conductivity (AHC) and giant anomalous Hall\nangle (AHA) simultaneously at low fields. The giant AHE in Co$_3$Sn$_2$S$_2$ is\nrobust against small-scale doping-related chemical potential changes. In this\nwork, we unveil a selective and co-chemical doping route to maximize AHEs in\nCo$_3$Sn$_2$S$_2$. To begin with, in Co$_3$Sn$_{2-x}$In$_x$S$_2$, we brought\nthe chemical potential at the hotspot of Berry curvature along with a maximum\nof asymmetric impurity scattering in high mobility region. As a result at\nx=0.05, we found a significant enhancement of AHA (95%) and AHC (190%) from the\nsynergistic enhancement of extrinsic and intrinsic mechanisms from modified\nBerry curvature of gaped nodal lines. Later, with anticipation of further\nimprovements in AHE, we grew hole-co-doped\nCo$_{3-y}$Fe$_y$Sn$_{2-x}$In$_x$S$_2$ crystals, where we found rather a\nsuppression of AHEs. The role of dopants in giving extrinsic effects or band\nbroadening can be better understood when chemical potential does not change\nafter doping. By simultaneous and equal co-doping with electrons and holes in\nCo$_{3-y-z}$Fe$_y$Ni$_z$Sn$_2$S$_2$, we kept the chemical potential unchanged.\nHenceforth, we found a significant enhancement in intrinsic AHC $\\sim$116% due\nto the disorder broadenings in kagome bands"
    },
    {
        "anchor": "Suppression of telegraph noise in a CPP spin valve by an oscillating\n  spin torque: Numerical study: The phenomenon of stochastic resonance (SR) has been mainly studied in\none-dimensional systems with additive noise. We show that in higher dimensional\nsystems and in the presence of multiplicative noise, a non-linear magnetic\nsystem with a strongly periodic current can show behavior similar to that of SR\nbut only for frequencies below the ferromagnetic resonance (FMR) frequency of\nthe system. Such a phenomena can provide an effective way to suppress low\nfrequency noise in spin valve magnetic sensors.",
        "positive": "Optimizing Thermoelectric Power Factor by Means of a Potential Barrier: Large efforts in improving thermoelectric energy conversion are devoted to\nenergy filtering by nanometer size potential barriers. In this work we perform\nan analysis and optimization of such barriers for improved energy filtering. We\nmerge semiclassical with quantum mechanical simulations to capture tunneling\nand reflections due to the barrier, and analyze the influence of the width W,\nthe height Vb, and the shape of the barrier, and the position of the Fermi\nlevel (EF) above the band edge, {\\eta}F. We show that for an optimized design,\napprox. 40 per cent improvement in the thermoelectric power factor can be\nachieved if the following conditions are met: {\\eta}F is large; the different\nof Vb from EF is somewhat higher but comparable to kBT; and W is large enough\nto suppress tunneling. Finally, we show that a smooth energy barrier is\nbeneficial compared to a sharp (square) barrier for increasing the\nthermoelectric power factor."
    },
    {
        "anchor": "Local segregation versus irradiation effects in high-entropy alloys:\n  Steady-state conditions in a driven system: We study order transitions and defect formation in a model high-entropy alloy\n(CuNiCoFe) under ion irradiation by means of molecular dynamics simulations.\nUsing a hybrid Monte-Carlo/molecular dynamics scheme a model alloy is generated\nwhich is thermodynamically stabilized by configurational entropy at elevated\ntemperatures, but partly decomposes at lower temperatures by copper\nprecipation. Both the high-entropy and the multiphase sample are then subjected\nto simulated particle irradiation. The damage accumulation is analyzed and\ncompared to an elemental Ni reference system. The results reveal that the\nhigh-entropy alloy---independent of the initial configuration---installs a\ncertain fraction of short-range order even under particle irradiation.\nMoreover, the results provide evidence that defect accumulation is reduced in\nthe high-entropy alloy. This is because the reduced mobility of point defects\nleads to a steady state of defect creation and annihilation. The lattice\ndefects generated by irradiation are shown to act as sinks for Cu segregation.",
        "positive": "Properties of metallic films in precise calculation of the Casimir force: Optical properties of the deposited gold films are discussed in connection\nwith the Casimir force prediction. Voids in the films and electron scattering\non the grain boundaries reduce the force at small separations on the 2% level\nin comparison with the bulk material prediction. The contribution of the patch\npotential due to polycrystalline structure of the films is shown to be small\nfor the existing Casimir force experiments."
    },
    {
        "anchor": "Anisotropic heat conduction in silicon nanowire network revealed by\n  Raman scattering: Anisotropic nanomaterials possess interesting thermal transport properties\nbecause they allow orientation of heat fluxes along preferential directions due\nto a high ratio (up to three orders of magnitude) between their in-plane and\ncross-plane thermal conductivities. Among different techniques allowing thermal\nconductivity evaluation, micro-Raman scattering is known to be one of the most\nefficient contactless measurement approaches. In this letter, a new\nexperimental approach based on Raman scattering measurements with variable\nlaser spot sizes is reported. Correlation between experimental and calculated\nthermal resistances of one-dimensional nanocrystalline solids allows\nsimultaneous estimation of their in-plane and cross-plane thermal\nconductivities. In particular, our measurement approach is illustrated to be\nsuccessfully applied for anisotropic thermal conductivity evaluation of silicon\nnanowire arrays.",
        "positive": "MOFSimplify: Machine Learning Models with Extracted Stability Data of\n  Three Thousand Metal-Organic Frameworks: We report a workflow and the output of a natural language processing\n(NLP)-based procedure to mine the extant metal-organic framework (MOF)\nliterature describing structurally characterized MOFs and their solvent removal\nand thermal stabilities. We obtain over 2,000 solvent removal stability\nmeasures from text mining and 3,000 thermal decomposition temperatures from\nthermogravimetric analysis data. We assess the validity of our NLP methods and\nthe accuracy of our extracted data by comparing to a hand-labeled subset.\nMachine learning (ML, i.e. artificial neural network) models trained on this\ndata using graph- and pore-geometry-based representations enable prediction of\nstability on new MOFs with quantified uncertainty. Our web interface,\nMOFSimplify, provides users access to our curated data and enables them to\nharness that data for predictions on new MOFs. MOFSimplify also encourages\ncommunity feedback on existing data and on ML model predictions for\ncommunity-based active learning for improved MOF stability models."
    },
    {
        "anchor": "Reduction in Rebound of Concrete Piles Driven into Clays by Coating Pile\n  Surface with Titanium Dioxide Nanoparticles: Using a model for concrete piles driven into clays, we compared penetration\ndepths between uncoated piles and piles coated with titanium dioxide (TiO2)\nnanoparticles. The behavior of surfaces coated with TiO2 changes to\nsuperhydrophilic, enabling water molecules to penetrate inside the clay pores.\nThe attraction suppresses or reduces the compression of water inside the clay\npores. The absence of bulk pressure from water causes the pile not to bounce\n(backward movement after striking). Contrary to hydrophobic surfaces, which\ntend to repel water molecules, water is compressed into the clay pores\ngenerating a bulk pressure that induces a countering upward force (resulting in\nrebounding). Driving tests for two types of clay demonstrate the absence of\nbouncing from coated piles. An examination of the pile surfaces indicates the\nformation of bonds between water molecules and coated surface and the absence\nof such bonding for uncoated piles. This finding might accelerate the process\nof pile driving at any civil engineering construction site.",
        "positive": "Phonon Modes in Single-Walled Molybdenum Disulphide (MoS2) Nanotubes:\n  Lattice Dynamics Calculation and Molecular Dynamics Simulation: We study the phonon modes in single-walled MoS$_{2}$ nanotubes via the\nlattice dynamics calculation and molecular dynamics simulation. The phonon\nspectra for tubes of arbitrary chiralities are calculated from the dynamical\nmatrix constructed by the combination of an empirical potential with the\nconserved helical quantum numbers $(\\kappa, n)$. In particular, we show that\nthe frequency ($\\omega$) of the radial breathing mode is inversely proportional\nto the tube diameter ($d$) as $\\omega=665.3/d$ {cm$^{-1}$}. The eigen vectors\nof the first twenty lowest-frequency phonon modes are illustrated. Based on\nthese eigen vectors, we demonstrate that the radial breathing oscillation is\ndisturbed by phonon modes of three-fold symmetry initially, and the tube is\nsquashed by the modes of two-fold symmetry eventually. Our study provides\nfundamental knowledge for further investigations of the thermal and mechanical\nproperties of the MoS$_{2}$ nanotubes."
    },
    {
        "anchor": "Improper magnetic ferroelectricity of nearly pure electronic nature in\n  cycloidal spiral CaMn$_{7}$O$_{12}$: The noncollinear cycloidal magnetic order breaks the inversion symmetry in\nCaMn$_{7}$O$_{12}$, generating one of the largest spin-orbit driven\nferroelectric polarizations measured to date. In this Letter, the microscopic\norigin of the polarization, including its direction, charge density\nredistribution, magnetic exchange interactions, and its coupling to the spin\nhelicity, is explored via first principles calculations. The Berry phase\ncomputed polarization exhibits almost pure electronic behavior, as the Mn\ndisplacements are negligible, $\\approx$~0.7~m\\textrm{\\AA}. The polarization\nmagnitude and direction are both determined by the Mn spin current, where the\n\\emph{p}-\\emph{d} orbital mixing is driven by the inequivalent exchange\ninteractions within the \\emph{B}-site Mn cycloidal spiral chains along each\nCartesian direction. We employ the generalized spin-current model with\nHeisenberg-exchange Dzyaloshinskii-Moriya interaction energetics to provide\ninsight into the underlying physics of this spin-driven polarization.\nPersistent electronic polarization induced by helical spin order in nearly\ninversion-symmetric ionic crystal lattices suggests opportunities for ultrafast\nmagnetoelectric response.",
        "positive": "Fluctuating local moments, itinerant electrons and the magnetocaloric\n  effect: the compositional hypersensitivity of FeRh: We describe an ab-initio Disordered Local Moment Theory for materials with\nquenched static compositional disorder traversing first order magnetic phase\ntransitions. It accounts quantitatively for metamagnetic changes and the\nmagnetocaloric effect. For perfect stoichiometric B2-ordered FeRh, we calculate\nthe transition temperature of the ferromagnetic-antiferromagnetic transition to\nbe $T_t =$ 495K and a maximum isothermal entropy change in 2 Tesla of $|\\Delta\nS|= 21.1$ J~K$^{-1}$~kg$^{-1}$. A large (40\\%) component of $|\\Delta S|$ is\nelectronic. The transition results from a fine balance of competing electronic\neffects which is disturbed by small compositional changes - e.g. swapping just\n2\\% Fe of `defects' onto the Rh sublattice makes $T_t$ drop by 290K. This\nhypersensitivity explains the narrow compositional range of the transition and\nimpurity doping effects."
    },
    {
        "anchor": "Uniaxial Phase Transition in Si : Ab initio Calculations: Based on a previously proposed thermodynamic analysis, we study the relative\nstabilities of five Si phases under uniaxial compression using ab initio\nmethods. The five phases are diamond, beta-tin, sh, sc, and hcp structures. The\npossible phase-transition patterns were investigated by considering the phase\ntransitions between any two chosen phases of the five phases. By analyzing the\ndifferent conributions to the relative pahse stability, we identified the most\nimportant factors in reducing the phase-transition pressures at uniaxial\ncompression. We also show that it is possible to have phase transitions occur\nonly when the phases are under uniaxial compression, in spite of no phase\ntransition when under hydrostatic commpression. Taking all five phases into\nconsideration, the phase diagram at uniaxial compression was constructed for\npressures under 20 GPa. The stable phases were found to be diamond, beta-tin\nand sh structures, i.e. the same as those when under hydrostatic condition.\nAccording to the phase diagram, direct phase transition from the diamond to the\nsh phase is possible if the applied uniaxial pressures, on increasing, satisfy\nthe condition of Px>Pz. Simiilarly, the sh-to-beta-tin transition on\nincreeasing pressures is also possible if the applied uniaxial pressures are\nvaried from the condition of Px>Pz, on which the phase of sh is stable, to that\nof Px<Pz, on which the beta-tin is stable.",
        "positive": "Embedded magnetic phases in (Ga,Fe)N: the key role of growth temperature: The local chemistry, structure, and magnetism of (Ga,Fe)N nanocomposites\ngrown by metal organic vapor phase epitaxy is studied by high resolution\nsynchrotron x-ray diffraction and absorption, transmission electron microscopy,\nand superconducting quantum interference device magnetometry as a function of\nthe growth temperature $T_{\\mathrm{g}}$. Three contributions to the\nmagnetization are identified: i) paramagnetic -- originating from dilute and\nnon-interacting Fe$^{3+}$ ions substitutional of Ga, and dominating in layers\nobtained at the lowest considered $T_{\\mathrm{g}}$ (800$^{\\circ}$C); ii)\nsuperparamagnetic-like -- brought about mainly by ferromagnetic nanocrystals of\n$\\epsilon-$Fe$_3$N but also by $\\gamma'$-Fe$_4$N and by inclusions of elemental\n$\\alpha$- and $\\gamma$-Fe, and prevalent in films obtained in the intermediate\n$T_{\\mathrm{g}}$ range; iii) component linear in the magnetic field and\nassociated with antiferromagnetic interactions -- found to originate from\nhighly nitridated Fe$_x$N ($x \\leq$ 2) phases, like $\\zeta$-Fe$_2$N, and\ndetected in samples deposited at the highest employed temperature,\n$T_{\\mathrm{g}}$ = 950$^{\\circ}$C. Furthermore, depending on $T_{\\mathrm{g}}$,\nthe Fe-rich nanocrystals segregate towards the sample surface or occupy\ntwo-dimensional planes perpendicular to the growth direction."
    },
    {
        "anchor": "Low Ghz loss in sputtered epitaxial Fe: We show that sputtered, pure epitaxial iron films can have high-frequency\nloss as low as, or lower than, any known metallic ferromagnetic\nheterostructure. Minimum 34 Ghz ferromagnetic resonance (FMR) linewidths of 41\nOe are demonstrated, some ~ 5-10 % lower than the previous minimum reported for\nmolecular beam epitaxially (MBE) deposited Fe. Intrinsic and extrinsic damping\nhave been separated over 0-40 Ghz, giving a lower bound for intrinsic LL(G)\nrelaxation rates of lambda or G = 85 MHz (alpha = 0.0027) and extrinsic 50 Mhz.\nSwept frequency measurements indicate the potential for integrated frequency\ndomain devices with Q>100 at 30-40 Ghz.",
        "positive": "Phonon band structures of three-dimensional pentamode metamaterials: Three-dimensional pentamode metamaterials are artificial solids that\napproximately behave like liquids, which have vanishing shear modulus.\nPentamodes have recently become experimental reality. Here, we calculate their\nphonon band structures for various parameters. Consistent with static continuum\nmechanics, we find that compression and shear waves exhibit phase velocities\nthat can realistically be different by more than one order of magnitude.\nInterestingly, we also find frequency intervals with more than two octaves\nbandwidth in which pure single-mode behavior is obtained. Herein, exclusively\ncompression waves exist due to a complete three-dimensional band gap for shear\nwaves and, hence, no coupling to shear modes is possible. Such single-mode\nbehavior might, e.g., be interesting for transformation-elastodynamics\narchitectures."
    },
    {
        "anchor": "Implications and consequences of ferromagnetism universally exhibited by\n  inorganic nanoparticles: Occurrence of surface ferromagnetism in inorganic nanoprticles as a universal\nproperty not only explains many of the unusual magnetic features of oxidic thin\nfilms, but also suggests its possible use in creating new materials, as\nexemplified by multiferroic BaTiO3 nanoparticles. While the use of Mn-doped ZnO\nand such materials in spintronics appears doubtful, it is possible to have\nmaterials exhibiting coexistence of (bulk) superconductivity with (surface)\nferromagnetism.",
        "positive": "Ultraflat bands and shear solitons in Moir\u00e9 patterns of twisted\n  bilayer transition metal dichalcogenides: Ultraflat bands in twisted bilayers of two-dimensional materials have\npotential to host strong correlations, including the Mott-insulating phase at\nhalf-filling of the band. Using first principles density functional theory\ncalculations, we show the emergence of ultraflat bands at the valence band edge\nin twisted bilayer MoS$_2$, a prototypical transition metal dichalcogenide. The\ncomputed band widths, 5 meV and 23 meV for 56.5$^\\circ$ and 3.5$^\\circ$ twist\nangles respectively, are comparable to that of twisted bilayer graphene near\n'magic' angles. Large structural transformations in the Moir\\'e patterns lead\nto formation of shear solitons at stacking boundaries and strongly influence\nthe electronic structure. We extend our analysis for twisted bilayer MoS$_2$ to\nshow that flat bands can occur at the valence band edge of twisted bilayer\nWS$_2$, MoSe$_2$ and WSe$_2$ as well."
    },
    {
        "anchor": "Anomalous relaxations and chemical trends at III-V nitride non-polar\n  surfaces: Relaxations at nonpolar surfaces of III-V compounds result from a competition\nbetween dehybridization and charge transfer. First principles calculations for\nthe (110) and (10$\\bar{1}$0) faces of zincblende and wurtzite AlN, GaN and InN\nreveal an anomalous behavior as compared with ordinary III-V semiconductors.\nAdditional calculations for GaAs and ZnO suggest close analogies with the\nlatter. We interpret our results in terms of the larger ionicity (charge\nasymmetry) and bonding strength (cohesive energy) in the nitrides with respect\nto other III-V compounds, both essentially due to the strong valence potential\nand absence of $p$ core states in the lighter anion. The same interpretation\napplies to Zn II-VI compounds.",
        "positive": "An Automated Fully-Computational Framework to Construct Printability\n  Maps for Additively Manufactured Metal Alloys: In additive manufacturing, the optimal processing conditions need to be\ndetermined to fabricate porosity-free parts. For this purpose, the design space\nfor an arbitrary alloy needs to be scoped and analyzed to identify the areas of\ndefects for different laser power-scan speed combinations and can be visualized\nusing a printability map. Constructing printability maps is typically a costly\nprocess due to the involvement of experiments, which restricts their\napplication in high-throughput product design. To reduce the cost and effort of\nconstructing printability maps, a fully computational framework is introduced\nin this work. The framework combines CALPHAD models and a reduced-order model\nto predict material properties. THen, an analytical thermal model, known as the\nEagar-Tsai model, utilizes some of these materials' properties to calculate the\nmelt pool geometry during the AM processes. In the end, printability maps are\nconstructed using material properties, melt pool dimensions, and commonly used\ncriteria for lack of fusion, balling, and keyholing defects. To validate the\nframework and its general application to laser powder-bed fusion alloys, five\ncommon additive manufacturing alloys are analyzed. Furthermore, NiTi-based\nalloys at three different compositions are evaluated to show the further\nextension of the framework to alloy systems at different compositions. The\ndefect regions in these printability maps are validated with corresponding\nexperimental observations to compare and benchmark the defect criteria and find\nthe optimal criterion set with the maximum accuracy for each unique material\ncomposition. Furthermore, printability maps for NiTi that are obtained from our\nframework are used in conjunction with process maps resulting from a\nmulti-model framework to guide the fabrication of defect-free additive\nmanufactured parts with tailorable properties and performance."
    },
    {
        "anchor": "Crystal structure prediction using the Minima Hopping method: A structure prediction method is presented based on the Minima Hopping\nmethod. Optimized moves on the configurational enthalpy surface are performed\nto escape local minima using variable cell shape molecular dynamics by aligning\nthe initial atomic and cell velocities to low curvature directions of the\ncurrent minimum. The method is applied to both silicon crystals and binary\nLennard-Jones mixtures and the results are compared to previous investigations.\nIt is shown that a high success rate is achieved and a reliable prediction of\nunknown ground state structures is possible.",
        "positive": "Electronic structure, mechanical and thermodynamic properties of ThN\n  from first-principles calculations: Lattice parameter, electronic structure, mechanical and thermodynamic\nproperties of ThN are systematically studied using the projector-augmented-wave\nmethod and the generalized gradient approximation based on the density\nfunctional theory. The calculated electronic structure indicates the important\ncontributions of Th 6\\emph{d}and 5\\emph{f} states to the Fermi-level electron\noccupation. Through Bader analysis it is found that the effective valencies in\nThN can be represented as Th$^{+1.82}$ N$^{-1.82}$. Elastic constant\ncalculations shows that ThN is mechanically stable and elastically anisotropic.\nFurthermore, the melting curve of ThN is presented up to 120 GPa. Based on the\nphonon dispersion data, our calculated specific heat capacities including both\nlattice and conduction-electron contributions agree well with experimental\nresults in a wide range of temperature."
    },
    {
        "anchor": "Stabilization mechanism of tetragonal structure in hydrothermal\n  synthesized BaTiO$_3$ nanocrystal: Higher OH concentration is identified in tetragonal barium titanate\n(BaTiO$_3$) nanorods synthesized by a hydrothermal method with 10 vol% ethylene\nglycol solvent [Inada, M. $et$ $al$. $Ceram.$ $Int.$ $2015$, $41$, 5581-5587].\nThis is apparently inconsistent with the known fact that higher OH\nconcentration in the conventional hydrothermal synthesis makes pseudo-cubic\nBaTiO$_3$ nanocrystals more stable than the tetragonal one. To understand where\nand how the introduced OH anions are located and behave in the nanocrystals, we\napplied $ab$ $initio$ analysis to several possible microscopic geometries of OH\nlocations, confirming the relative stability of the tetragonal distortion over\nthe pseudo-cubic one due to the preference of trans-type configurations of OH\nanions. We also performed FTIR and XRD analysis, all being in consistent with\nthe microscopic picture established by the $ab$ $initio$ geometrical\noptimizations.",
        "positive": "Ferromagnetic resonance in thin films - cross-validation analysis of\n  numerical solutions of Smit-Beljers equation. Application to GaMnAs: (Dated: August 3, 2018) The new method of numerical analysis of experimental\nferromagnetic resonance (FMR) spectra in thin films is developed and applied to\n(Ga,Mn)As thin films. Specifically, it starts with the finding of numerical\nsolutions of Smit-Beljers (SB) equation and continues with their subsequent\nstatistical analysis within the cross-validation (CV) approach taken from\nmachine learning techniques. As a result of this treatment, we are able to\nreinterpret the available FMR experimental results in diluted ferromagnetic\nsemiconductor (Ga,Mn)As thin films with the resulting determination of\nmagnetocrystalline anisotropy constants. The outcome of CV analysis points out\nthat it is necessary to take into account terms describing the bulk cubic\nanisotropy up to the fourth order to reproduce FMR experimental results for\n(Ga,Mn)As correctly. This finding contradicts the wide-spread conviction in the\nliterature that only first order cubic anisotropy term is important in this\nmaterial. We also provide numerical values of these higher order cubic\nanisotropy constants for (Ga,Mn)As thin films resulting from SB-CV approach."
    },
    {
        "anchor": "On fracture in finite strain gradient plasticity: In this work a general framework for damage and fracture assessment including\nthe effect of strain gradients is provided. Both mechanism-based and\nphenomenological strain gradient plasticity (SGP) theories are implemented\nnumerically using finite deformation theory and crack tip fields are\ninvestigated. Differences and similarities between the two approaches within\ncontinuum SGP modeling are highlighted and discussed. Local strain hardening\npromoted by geometrically necessary dislocations (GNDs) in the vicinity of the\ncrack leads to much higher stresses, relative to classical plasticity\npredictions. These differences increase significantly when large strains are\ntaken into account, as a consequence of the contribution of strain gradients to\nthe work hardening of the material. The magnitude of stress elevation at the\ncrack tip and the distance ahead of the crack where GNDs significantly alter\nthe stress distributions are quantified. The SGP dominated zone extends over\nmeaningful physical lengths that could embrace the critical distance of several\ndamage mechanisms, being particularly relevant for hydrogen assisted cracking\nmodels. A major role of a certain length parameter is observed in the multiple\nparameter version of the phenomenological SGP theory. Since this also dominates\nthe mechanics of indentation testing, results suggest that length parameters\ncharacteristic of mode I fracture should be inferred from nanoindentation.",
        "positive": "Prediction of thermal cross-slip stress in magnesium alloys from direct\n  first principles data: We develop a first-principles model of thermally-activated cross-slip in\nmagnesium in the presence of a random solute distribution. Electronic structure\nmethods provide data for the interaction of solutes with prismatic dislocation\ncores and basal dislocation cores. Direct calculations of interaction energies\nare possible for solutes---K, Na, and Sc---that lower the Mg prismatic stacking\nfault energy to improve formability. To connect to thermally activated\ncross-slip, we build a statistical model for the distribution of activation\nenergies for double kink nucleation, barriers for kink migration, and roughness\nof the energy landscape to be overcome by an athermal stress. These\ndistributions are calculated numerically for a range of concentrations, as well\nas alternate approximate analytic expressions for the dilute limit. The\nanalytic distributions provide a simplified model for the maximum cross-slip\nsoftening for a solute as a function of temperature. The direct interaction\ncalculations predict lowered forming temperatures for Mg-0.7at.%Sc,\nMg-0.4at.%K, and Mg-0.6at.%Na of approximately 250C."
    },
    {
        "anchor": "A Multi-Component Phase Field Crystal Model for Structural\n  Transformations in Metal Alloys: We present a new phase field crystal model for structural transformations in\nmulti-component alloys. The formalism builds upon the two-point correlation\nkernel developed in Greenwood et al. for describing structural transformations\nin pure materials [Phys. Rev. Lett. 105, 045702 (2010)]. We introduce an\neffective twopoint correlation function for multi-component alloys that uses\nthe local species concentrations to interpolate between different crystal\nstructures. A simplified version of the model is derived for the particular\ncase of threecomponent (ternary) alloys, and its equilibrium properties are\ndemonstrated. Dynamical equations of motion for the density and multiple\nspecies concentration fields are derived, and the robustness of the model is\nillustrated with examples of complex microstructure evolution in dendritic\nsolidification and solid-state precipitation.",
        "positive": "Electron-Hole Separation in Ferroelectric Oxides for Efficient\n  Photovoltaic Responses: Despite their potential to exceed the theoretical Shockley-Queisser limit,\nferroelectric photovoltaics (FPVs) have performed inefficiently due to their\nextremely low photocurrents. Incorporating Bi2FeCrO6 (BFCO) as the light\nabsorber in FPVs has recently led to impressively high and record photocurrents\n[Nechache et al. Nature Photon. 2015, 9, 61], reviving the FPV field. However,\nour understanding of this remarkable phenomenon is far from satisfactory. Here,\nwe use first-principles calculations to determine that such excellent\nperformance mainly lies in the efficient separation of electron-hole (e-h)\npairs. We show that photoexcited electrons and holes in BFCO are spatially\nseparated on the Fe and Cr sites, respectively. This separation is much more\npronounced in disordered BFCO phases, which show exceptional PV responses. We\nfurther set out to design a strategy for next-generation FPVs, not limited to\nBFCO, by exploring 44 additional Bi-based double-perovskite oxides. We suggest\n9 novel active-layer materials that can offer strong e-h separations and a\ndesired band gap energy for application in FPVs. Our work indicates that charge\nseparation is the most important issue to be addressed for FPVs to compete with\nconventional devices."
    },
    {
        "anchor": "Fast determination of phases in LiFePO4 using low losses in electron\n  energy-loss spectroscopy: Experimental valence electron energy loss spectra (VEELS), up to the Li K\nedge, obtained on different phases of LixFePO4 are compared to first principles\ncalculations using the density functional code WIEN2k. In the 4-7 eV range, a\nlarge peak is identified in the FePO4 spectrum, but is absent in LiFePO4, which\ncould allow the easy formation of energy filtered images. The intensity of this\npeak, non sensitive to the precise orientation of the crystal, is large enough\nto rapidly determine existing phases in the sample and permit future dynamical\nstudies. Solid solution and two-phases regions are also differentiated using Fe\nM2,3 / Li K edges.",
        "positive": "Exactly solvable model of the ferroelectrics hysteresis loops control by\n  the external electric field: The kinetic theory of switching processes in crystalline ferroelectric\nmaterials under the influence of a variable external electric field is\nformulated. The basic equations are derived and their exact analytical solution\nat arbitrary time-dependent external field are obtained. Connection between the\nhysteresis loops shape and variable external electric field parameters is\ninvestigated numerically. The numerical results were found to be in excellent\nagreement with the experiments. PACS: 77.80.Fm, 77.80.Dj, 77.80.-e Keywords:\nferroelectrics, switching processes, hysteresis curves, polarization"
    },
    {
        "anchor": "Energy dependent amplitude of Brillouin oscillations in GaP: Gallium phosphide is an important indirect band gap material with variety of\napplications in optics ranging from LEDs to applications in GaP/Si based solar\ncells. We investigated GaP using ultrafast, pump-probe coherent acoustic phonon\nspectroscopy (time-domain Brillouin scattering). We measured the dependence of\nthe amplitude of the differential reflectivity as modulated by coherent\nacoustic phonons (CAPs) as a function of laser probe energy and found that the\namplitude of the coherent phonon oscillations varies non-monotonically near the\ndirect gap transition at the $\\Gamma$ point. A theoretical model is developed\nwhich quantitatively explains the experimental data and shows that one can use\ncoherent phonon spectroscopy to provide detailed information about the\nelectronic structure, the dielectric function and optical transitions in\nindirect band gap materials. Our calculations show that the modelling of\nexperimental results is extremely sensitive to the wavelength dependent\ndielectric function and its derivatives.",
        "positive": "Magneto-Optical Detection of the Spin Hall Effect in Pt and W Thin Films: Here we report the measurement of the interfacial spin accumulation induced\nby the spin Hall effect in Pt and W thin films using magneto-optical Kerr\nmicroscopy. We show that the Kerr rotation has opposite sign in Pt and W and\nscales linearly with current density. By comparing the experimental results\nwith ab-initio calculations of the spin Hall and magneto-optical Kerr effects,\nwe quantitatively determine the current-induced spin accumulation at the Pt\ninterface as $5*10^{-12} \\mu_B$A$^{-1}$cm$^2$ per atom. From\nthickness-dependent measurements, we determine the spin diffusion length in a\nsingle Pt film to be $11 \\pm 3$ nm, which is significantly larger compared to\nthat of Pt adjacent to a magnetic layer."
    },
    {
        "anchor": "Dynamics of a magnetic dimer with exchange, dipolar and\n  Dzyalozhinski-Moriya interaction: We investigate the dynamics of a magnetic system consisting of two magnetic\nmoments coupled by either exchange, dipole-dipole, or Dzyalozhinski-Moriya\ninteraction. We compare the switching mechanisms and switching rates as induced\nby the three couplings. For each coupling and each configuration of the two\nanisotropy axes, we describe the switching modes and, using the kinetic theory\nof Langer, we provide (semi-)analytical expressions for the switching rate. We\nthen compare the three interactions with regard to their efficiency in the\nreversal of the net magnetic moment of the dimer. We also investigate how the\nenergy barriers vary with the coupling. For the dipole-dipole interaction we\nfind that the energy barrier may either increase or decrease with the coupling\ndepending on whether the latter is weak or strong. Finally, upon comparing the\nvarious switching rates, we find that the dipole-dipole coupling leads to the\nslowest magnetic dimer, as far as the switching of its net magnetic moment is\nconcerned.",
        "positive": "Termination control of magnetic coupling at a complex oxide interface: Atomically flat interfaces between ternary oxides have chemically different\nvariants, depending on the terminating lattice planes of both oxides.\nElectronic properties change with the interface termination which affects, for\ninstance, charge accumulation and magnetic interactions at the interface.\nWell-defined terminations have yet rarely been achieved for oxides of ABO3 type\n(with metals A, B). Here, we report on a strategy of thin film growth and\ninterface characterization applied to fabricate the La0.7Sr0.3MnO3-SrRuO3\ninterface with controlled termination. Ultra-strong antiferromagnetic coupling\nbetween the ferromagnets occurs at the MnO2-SrO interface, but not for the\nother termination, in agreement with density functional calculations. X-ray\nmagnetic circular dichroism measurements reveal coupled reversal of Mn and Ru\nmagnetic moments at the MnO2-SrO interface. Our results demonstrate termination\ncontrol of magnetic coupling across a complex oxide interface and provide a\npathway for theoretical and experimental explorations of novel electronic\ninterface states with engineered magnetic properties."
    },
    {
        "anchor": "Energy barriers for diffusion on stepped Pt(111) surface: We performed molecular statics calculations of energy barriers for adatom\nmoves in the vicinity of steps on Pt(111) surface. We used the semi-empirical\nmany-body Rosato--Guillope--Legrand potential and we systematically calculated\nbarriers for descent of straight steps, steps with a kink and small islands as\nwell as barriers for diffusion along the step edges. We confirmed that the\nlowest barrier for descent is for an exchange process near kink's or island's\ncorner on a step with a {111} microfacet. Diffusion along a step with a {111}\nmicrofacet is faster than along a step with a {100} microfacet. We also\ncalculated barriers for diffusion on several surfaces vicinal to Pt(111). Our\nresults are compared with previous calculations.",
        "positive": "Crystallization of the Wahnstr\u00f6m Binary Lennard-Jones Liquid: We report observation of crystallization of the glass-forming binary\nLennard-Jones liquid first used by Wahnstr\\\"om [G. Wahnstr\\\"om, Phys. Rev. A\n44, 3752 (1991)]. Molecular dynamics simulations of the metastable liquid on a\ntimescale of microseconds were performed. The liquid crystallized\nspontaneously. The crystal structure was identified as MgZn_2. Formation of\ntransient crystallites is observed in the liquid. The crystallization is\ninvestigate at different temperatures and compositions. At high temperature the\nrate of crystallite formation is the limiting factor, while at low temperature\nthe limiting factor is growth rate. The melting temperature of the crystal is\nestimated to be T_m=0.93 at rho=0.82. The maximum crystallization rate of the\nA_2B composition is T=0.60+/-0.02."
    },
    {
        "anchor": "Density-Functional Theory of Surface Diffusion and Epitaxial Growth of\n  Metals: This paper gives a summary of basic concepts of density-functional theory\n(DFT) and its use in state-of-the-art computations of complex processes in\ncondensed matter physics and materials science. In particular we discuss how\nmicroscopic growth parameters can be determined by DFT and how on this basis\nmacroscopic phenomena can be described. To reach the time and length scales of\nrealistic growth conditions, DFT results are complemented by kinetic Monte\nCarlo simulations.",
        "positive": "Temperature dependence of the electron spin resonance linewidth in\n  magnetic insulators: We analyze the temperature dependence of the electron spin resonance\nlinewidth above the critical region in exchange-coupled magnetic insulators.\nThe focus is on separating the contributions to the linewidth from spin-spin\ninteractions, spin-one-phonon interactions and spin-two-phonon interactions at\ntemperatures where the spin-spin term is constant and the one- and two-phonon\nterms vary as T and T^2, respectively. Taking Co3O4 as an example, we use a\nleast squares fit over the temperature range 50 K < T < 500 K to obtain values\nof the three components. It is found that the spin-spin mechanism is dominant\nbelow 100 K, while the two-phonon mechanism is most important above 250 K. In\nthe intermediate region, all three mechanisms make significant contributions."
    },
    {
        "anchor": "Understanding how off-stoichiometry promotes cation mixing in LiNiO$_2$: Although LiNiO$_2$ is chemically similar to LiCoO$_2$ and offers a nearly\nidentical theoretical capacity, LiNiO$_2$ and related Co-free Ni-rich cathode\nmaterials suffer from degradation during electrochemical cycling that has\nprevented practical use in Li-ion batteries. The observed capacity decay of\nLiNiO$_2$ has been attributed to the formation of structural defects via Li/Ni\ncation mixing that reduces cyclability and leads to poor capacity retention.\nHerein, we investigate the kinetics and thermodynamics of Li/Ni mixing in ideal\nLiNiO$_2$ and off-stoichiometric Li$_{1-z}$Ni$_{1+z}$O$_2$. We find that ideal\nLiNiO$_2$ is stable against cation mixing with similar characteristics as\nLiCoO$_2$. Li/Ni mixing is promoted by extra Ni in the Li layers that cannot be\navoided in synthesis. Our study elucidates the crucial role of extra Ni atoms\non Li sites in the cation mixing mechanism, an insight that can inform the\ndevelopment of Co-free cathode materials.",
        "positive": "Ab Initio Bethe-Salpeter Equation Approach to Neutral Excitations in\n  Molecules with Numeric Atom-Centered Orbitals: The Bethe-Salpeter equation (BSE) based on GW quasiparticle levels is a\nsuccessful approach for calculating the optical gaps and spectra of solids and\nalso for predicting the neutral excitations of small molecules. We here present\nan all-electron implementation of the GW+BSE formalism for molecules, using\nnumeric atom-centered orbital (NAO) basis sets. We present benchmarks for\nlow-lying excitation energies for a set of small organic molecules, denoted in\nthe literature as \"Thiel's set\". Literature reference data based on\nGaussian-type orbitals are reproduced to about one meV precision for the\nmolecular benchmark set, when using the same GW quasiparticle energies and\nbasis sets as the input to the BSE calculations. For valence correlation\nconsistent NAO basis sets, as well as for standard NAO basis sets for ground\nstate density-functional theory with extended augmentation functions, we\ndemonstrate excellent convergence of the predicted low-lying excitations to the\ncomplete basis set limit. A simple and affordable augmented NAO basis set\ndenoted \"tier2+aug2\" is recommended as a particularly efficient formulation for\nproduction calculations. We finally demonstrate that the same convergence\nproperties also apply to linear-response time-dependent density functional\ntheory within the NAO formalism."
    },
    {
        "anchor": "Exploring Physics of Ferroelectric Domain Walls in Real Time: Deep\n  Learning Enabled Scanning Probe Microscopy: The functionality of ferroelastic domain walls in ferroelectric materials is\nexplored in real-time via the in-situ implementation of computer vision\nalgorithms in scanning probe microscopy (SPM) experiment. The robust deep\nconvolutional neural network (DCNN) is implemented based on a deep residual\nlearning framework (Res) and holistically-nested edge detection (Hed), and\nensembled to minimize the out-of-distribution drift effects. The DCNN is\nimplemented for real-time operations on SPM, converting the data stream into\nthe semantically segmented image of domain walls and the corresponding\nuncertainty. We further demonstrate the pre-selected experimental workflows on\nthus discovered domain walls, and report alternating high- and low-\npolarization dynamic (out-of-plane) ferroelastic domain walls in a (PbTiO3) PTO\nthin film and high polarization dynamic (out-of-plane) at short ferroelastic\nwalls (compared with long ferroelastic walls) in a lead zirconate titanate\n(PZT) thin film. This work establishes the framework for real-time DCNN\nanalysis of data streams in scanning probe and other microscopies and\nhighlights the role of out-of-distribution effects and strategies to ameliorate\nthem in real time analytics.",
        "positive": "Femtosecond Demagnetization and Hot Hole Relaxation in Ferromagnetic\n  GaMnAs: We have studied ultrafast photoinduced demagnetization in GaMnAs via\ntwo-color time-resolved magneto-optical Kerr spectroscopy. Below-bandgap\nmidinfrared pump pulses strongly excite the valence band, while near-infrared\nprobe pulses reveal sub-picosecond demagnetization that is followed by an\nultrafast ($\\sim$1 ps) partial recovery of the Kerr signal. Through comparison\nwith InMnAs, we attribute the signal recovery to an ultrafast energy relaxation\nof holes. We propose that the dynamical polarization of holes through $p$-$d$\nscattering is the source of the observed probe signal. These results support\nthe physical picture of femtosecond demagnetization proposed earlier for\nInMnAs, identifying the critical roles of both energy and spin relaxation of\nhot holes."
    },
    {
        "anchor": "Topological quantum switch and controllable quasi 1D wires in antimonene: Based on the recently found non-trivial topology of buckled antimonene, we\npropose the conceptual design of a quantized switch that is protected by\ntopology and a mechanism to create configurable 1D wire channels.\n  We show that the topologically required edge states in this system can be\nturned on and off by breaking the inversion symmetry (reducing the symmetry\nfrom $S_6$ to $C_3$), which can be achieved by gating the system. This is shown\nto create a field-effect quantum switch projected by topology.\n  Secondly we show that by locally gating the system with different polarity in\ndifferent areas, a soliton-like domain wall is created at their interface,\nwhich hosts a protected electronic state, in which transport could be accessed\nby gated doping.",
        "positive": "Low energy phases of bilayer Bi predicted by structure search in two\n  dimensions: We employ an ab-initio structure search algorithm to explore the\nconfigurational space of Bi in quasi two dimensions. A confinement potential\nrestricts the movement of atoms within a pre-defined thickness during structure\nsearch calculations within the minima hopping method to find the stable and\nmetastable forms of bilayer Bi. In addition to recovering the two known\nlow-energy structures (puckered monoclinic and buckled hexagonal), our\ncalculations predict three new structures of bilayer Bi. We call these\nstructures the $\\alpha$, $\\beta$, and $\\gamma$ phases of bilayer Bi, which are,\nrespectively, 63, 72, and 83 meV/atom higher in energy than that of the\nmonoclinic ground state, and thus potentially synthesizable using appropriate\nsubstrates. We also compare the structural, electronic, and vibrational\nproperties of the different phases. The puckered monoclinic, buckled hexagonal,\nand $\\beta$ phases exhibit a semiconducting energy gap, whereas $\\alpha$ and\n$\\gamma$ phases are metallic. We notice an unusual Mexican-hat type band\ndispersion leading to a van Hove singularity in the buckled hexagonal bilayer\nBi. Notably, we find symmetry-protected topological Dirac points in the\nelectronic spectrum of the $\\gamma$ phase. The new structures suggest that\nbilayer Bi provides a novel playground to study distortion-mediated\nmetal-insulator phase transitions."
    },
    {
        "anchor": "Probing the Electronic Structure of Bilayer Graphene by Raman Scattering: The electronic structure of bilayer graphene is investigated from a resonant\nRaman study using different laser excitation energies. The values of the\nparameters of the Slonczewski-Weiss-McClure model for graphite are measured\nexperimentally and some of them differ significantly from those reported\npreviously for graphite, specially that associated with the difference of the\neffective mass of electrons and holes. The splitting of the two TO phonon\nbranches in bilayer graphene is also obtained from the experimental data. Our\nresults have implications for bilayer graphene electronic devices.",
        "positive": "Effect of Interfacial Dipole on Heterogeneous Ice Nucleation: In this letter, we performed molecular dynamics simulations of ice nucleation\non a rigid surface model of cubic zinc blende structure with different surface\ndipole strength and orientation. It follows that, despite the excellent lattice\nmatch between cubic ice and substrates, the ice nucleation happened only when\nthe interfacial water molecules (IWs) have the same or similar orientations as\nthat of the water molecules in cubic ice. The free energy landscapes revealed\nthat, for substrates with improper dipole strength/orientation, large free\nenergy barriers arose to prevent the dipole of IWs rotating to the right\norientation to trigger ice formation. Our results suggest that the traditional\nconcept of lattice match, the similarity of lattice length between a substrate\nand the new-formed crystalline, should be extended to a broader match include\nthe similarity between the molecular orientations of the interfacial component\nand the component in the specific new-formed crystalline face."
    },
    {
        "anchor": "Tuning skyrmions in B20 compounds by 4d and 5d doping: Skyrmion stabilization in novel magnetic systems with the B20 crystal\nstructure is reported here, primarily based on theoretical results. The focus\nis on the effect of alloying on the 3d sublattice of the B20 structure by\nsubstitution of heavier 4d and 5d elements, with the ambition to tune the\nspin-orbit coupling and its influence on magnetic interactions.\nState-of-the-art methods based on density functional theory are used to\ncalculate both isotropic and anisotropic exchange interactions. Significant\nenhancement of the Dzyaloshinskii-Moriya interaction is reported for 5d-doped\nFeSi and CoSi, accompanied by a large modification of the spin stiffness and\nspiralization. Micromagnetic simulations coupled to atomistic spin-dynamics and\nab initio magnetic interactions reveal a helical ground state and field-induced\nskyrmions for all these systems. Especially small skyrmions $\\sim$50 nm are\npredicted for Co$_{0.75}$Os$_{0.25}$Si, compared to $\\sim$148 nm for\nFe$_{0.75}$Co$_{0.25}$Si. Convex-hull analysis suggests that all B20 compounds\nconsidered here are structurally stable at elevated temperatures and should be\npossible to synthesize. This prediction is confirmed experimentally by\nsynthesis and structural analysis of the Ru-doped CoSi systems discussed here,\nboth in powder and in single-crystal forms.",
        "positive": "Tuning the Catalytic Properties of Monolayer MoS2 through doping and\n  sulfur vacancies: Fuel cells in vehicles are the leading cause of carbon monoxide emissions. CO\nis one of the most dangerous gases in the atmosphere, as it binds to the\nhemoglobin in blood cells 200 times easier than O2. As the amount of CO in the\nblood stream increases, the level of oxygen decreases, which can lead to many\nneurological problems. To reduce the amount of CO in the atmosphere, scientists\nhave focused on the adsorption of oxygen. The best substrates used today are\nplatinum and palladium monolayers, which are very expensive. Because of this,\nresearchers have searched for cheap materials, such as MoS2, that are able to\nadsorb oxygen. However, sulfur is a chemically inert site for the oxygen, which\ngreatly decreases the catalytic potential of monolayer MoS2 sheets. Therefore,\nwe carried out first-principles calculations to study the effect of\nsubstitutional doping and creating sulfur vacancies on the catalytic properties\nof MoS2. We calculated the adsorption energy of O on doped MoS2 sheets with\nvacancies, and compared it to the adsorption energy of O on a Pd monolayer. We\nfound that doping MoS2 with Ir, Rh, Co and Fe significantly decreased the\nadsorption energy, to below -4 eV, indicating that doped MoS2 is a more\neffective catalyst than Pd. Incorporating sulfur vacancies into the doped MoS2\nsheet was extremely effective, and decreased the adsorption energy below -6 eV.\nOur results show that iridium is the best catalyst as it has the lowest\nadsorption energy before and after sulfur vacancies were induced. We concluded\nthat a combination of doping and creating vacancies in monolayer MoS2 sheets\ncan greatly impact the catalytic behavior and make it a more effective, less\nexpensive catalyst than Pt and Pd."
    },
    {
        "anchor": "To see or not to see: Imaging surfactant coated nano--particles using\n  HIM and SEM: Nano--particles are of great interest in fundamental and applied research.\nHowever, their accurate visualization is often difficult and the interpretation\nof the obtained images can be complicated. We present a comparative scanning\nelectron microscopy and helium ion microscopy study of\ncetyltrimethylammonium--bromide (CTAB) coated gold nano--rods. Using both\nmethods we show how the gold core as well as the surrounding thin CTAB shell\ncan selectively be visualized. This allows for a quantitative determination of\nthe dimensions of the gold core or the CTAB shell. The obtained CTAB shell\nthickness of 1.0 nm--1.5 nm is in excellent agreement with earlier results\nusing more demanding and reciprocal space techniques.",
        "positive": "Optimization of graphene dry etching conditions via combined microscopic\n  and spectroscopic analysis: Single-layer graphene structures and devices are commonly defined using\nreactive ion etching and plasma etching with O2 or Ar as the gaseous etchants.\nAlthough optical microscopy and Raman spectroscopy are widely used to determine\nthe appropriate duration of dry etching, additional characterization with\natomic force microscopy (AFM) reveals that residual graphene and/or etching\nbyproducts persist beyond the point where the aforementioned methods suggest\ncomplete graphene etching. Recognizing that incomplete etching may have\ndeleterious effects on devices and/or downstream processing, AFM\ncharacterization is used here to determine optimal etching conditions that\neliminate graphene dry etching residues."
    },
    {
        "anchor": "0.71-\u00c5 resolution electron tomography enabled by deep learning aided\n  information recovery: Electron tomography, as an important 3D imaging method, offers a powerful\nmethod to probe the 3D structure of materials from the nano- to the\natomic-scale. However, as a grant challenge, radiation intolerance of the\nnanoscale samples and the missing-wedge-induced information loss and artifacts\ngreatly hindered us from obtaining 3D atomic structures with high fidelity.\nHere, for the first time, by combining generative adversarial models with\nstate-of-the-art network architectures, we demonstrate the resolution of\nelectron tomography can be improved to 0.71 angstrom which is the highest\nthree-dimensional imaging resolution that has been reported thus far. We also\nshow it is possible to recover the lost information and remove artifacts in the\nreconstructed tomograms by only acquiring data from -50 to +50 degrees (44%\nreduction of dosage compared to -90 to +90 degrees full tilt series). In\ncontrast to conventional methods, the deep learning model shows outstanding\nperformance for both macroscopic objects and atomic features solving the\nlong-standing dosage and missing-wedge problems in electron tomography. Our\nwork provides important guidance for the application of machine learning\nmethods to tomographic imaging and sheds light on its applications in other 3D\nimaging techniques.",
        "positive": "Can Symmetric Tilt Grain Boundaries Represent Polycrystals?: Grain boundaries control a wide variety of bulk properties in polycrystalline\nmaterials, so simulation methods like density functional theory are routinely\nused to study their structure-property relationships. A standard practice for\nsuch simulations is to use compact, high-symmetry (coincident site lattice)\nboundaries as representatives of the much more complex polycrystalline grain\nboundaries. In this letter, we question this practice by quantitatively\ncomparing the spectra of atomic sites and properties amongst grain boundaries.\nWe show, using solute segregation as an example property, that highly symmetric\ntilt boundaries (with {\\Sigma} values less than 10) will fail to capture\npolycrystalline grain boundary environments, and thus lead to incorrect\nquantitative and qualitative insights into their behavior."
    },
    {
        "anchor": "Photon-Assisted Process and High-Harmonic Dynamic Localization in\n  Graphene Nanoribbons: We used a complete tight-binding band structure of graphene nanoribbon to\nobtain, for the first time, analytical techniques for observing photon assisted\ntransport, and dynamic localization of electrons in the graphene nanoribbons.\nWhen the ribbons are subject to a multi-frequency dc-ac field, photon assisted\nreplicas show up at rather strong drive force. The strong dependence of the\nphoton peaks on ac amplitudes allow for high-harmonic dynamic oscillations at\nthese amplitudes. We identified regions of positive differential conductivity\nwhere a nanoelectronic graphene device may be operated as a small signal\namplifier. Our research has also reveal another quantum mechanical phenomenon,\nfractional photon assisted transport, when the stark factor $r > 1$.",
        "positive": "Stroboscopic wave packet description of time-dependent currents through\n  ring-shaped nanostructures: We present an implementation of a new method for explicit simulations of\ntime-dependent electric currents through nanojunctions. The method is based on\nunitary propagation of stroboscopic wave packet states and is designed to treat\nopen systems with fluctuating number of electrons while preserving full quantum\ncoherence throughout the whole infinite system. We demonstrate the performance\nof the method on a model system consisting of a ring-shaped nanojunction with\ntwo semi-infinite tight-binding leads. Time-dependent electron current\nresponses to abrupt bias turn-on or gate potential switching are computed for\nseveral ring configurations and ring-leads coupling parameters. The found\ncurrent-carrying stationary states agree well with the predictions of the\nLandauer formula. As examples of genuinely time-dependent process we explore\nthe presence of circulating currents in the rings in transient regimes and the\neffect of a time-dependent gate potential."
    },
    {
        "anchor": "Influence of space charge on domain patterns and susceptibility in a\n  rhombohedral ferroelectric film: The presence of a space charge region induces an internal electric field\nwithin the charged region that, in a ferroelectric material, would rotate the\npolarisations to align with the field. The strength of the induced field would\ntherefore determine the domain patterns and polarisation switching properties\nof the material. Using a phase-field model, we investigate the effect of\ncharged layers in fully and partially depleted BiFeO$_3$ thin films in the\nrhombohedral phase. While the domain pattern in a charge-free BiFeO$_3$ film\nconsists of only two polarisation variants, we observe complex patterns with\nfour coexisting variants that form within the charged layers at sufficiently\nhigh induced fields. These variants form a head-to-head configuration with an\ninterface that is either wavy or planar depending on the internal field\nstrength, which is determined by the charge density as well as the thickness of\nthe charged layer. For depletion layers with sufficient thickness, there exists\na range of charge density values for which the interface is wavy, while at high\ndensities the interface becomes planar. We find that films with wavy interfaces\nexhibit enhanced susceptibilities with reduced hystereses compared to the\ncharge-free film. The results of our work suggest that introducing space charge\nregions by careful selection of dopant density and electrode materials can\nengineer domain patterns that yield a higher response with a smaller\nhysteresis.",
        "positive": "On the low-frequency spatial dispersion in wire media: The work is dedicated to the theoretic analysis of wire media, i.e. lattices\nof perfectly conducting wires comprised of two or three doubly periodic arrays\nof parallel wires which are orthogonal to one another. An analytical method\nbased on local field approach is used. The explicit dispersion equations are\npresented and studied. A possibility to introduce a dielectric permittivity is\ndiscussed. The theory is validated by comparison with the numerical data\navailable in the literature."
    },
    {
        "anchor": "Chirality-Induced Spin Filtering in Pseudo Jahn-Teller Molecules: Chirality-induced spin selectivity (CISS) refers to an ability to induce a\nspin polarization of an electron transmitted through chiral materials. An\nimportant experimental observation is that incredibly large spin polarization\nis realized at room temperature even for organic molecules that have weak\nspin-orbit coupling (SOC), although SOC is the only interaction that can\nmanipulate the electrons' spins in the setups. Therefore, the mechanism of the\nCISS needs to be constructed in a way insensitive to or enhancing the magnitude\nof the SOC strength. In this paper, we describe a theoretical study of CISS\nwith a model chiral molecule that belongs to the point group $\\mathrm{C}_3$. In\nthis molecule, electronic translational and rotational degrees of freedom for\nan injected electron are coupled to one another via the nuclear vibrational\nmode with a pseudo Jahn-Teller effect. By properly taking the molecular\nsymmetry as well as the time-reversal symmetry into account and classifying the\nmolecular ground states by their angular- and spin-momentum quantum numbers, we\nshow that the chiral molecule can act as an efficient spin filter. The\nefficiency of this spin filtering can be nearly independent of the SOC strength\nin this model, while it well exceeds the spin polarization relying solely on\nthe SOC. The nuclear vibrations turned out to have the role of not only\nmediating the translation-rotation coupling, but also enhancing the\nspin-filtering efficiency.",
        "positive": "The consequences of dependence between the formal area efficiency and\n  the macroscopic electric field on linearity behavior in Fowler-Nordheim plots: This work presents a theoretical explanation for a crossover in the linear\nbehavior in Fowler-Nordheim (FN) plots based on cold field electron emission\n(CFE) experimental data. It is characterized by a clear change in the decay\nrate of usually single-slope FN plots, and has been reported when non-uniform\nnano-emitters are subject to high macroscopic electric field $F_M$. We assume\nthat the number of emitting spots, which defines an apparent formal area\nefficiency of CFE surfaces, depends on the macroscopic electric field.\nNon-uniformity is described by local enhancement factors\n$\\left\\{\\gamma_j\\right\\}$, which are randomly assigned to each distinct emitter\nof a conducting CFE surface, from a discrete probability distribution\n$\\rho{(\\gamma_{j})}$, with $j=1,2$. It is assumed that $\\rho{(\\gamma_{1})} <\n\\rho{(\\gamma_{2})}$, and that $\\gamma_{1} > \\gamma_{2}$. The local current\ndensity is evaluated by considering a usual Schottky-Nordheim barrier. The\nresults reproduce the two distinct slope regimes in FN plots when $F_M \\in $\n$[2,20]$ V/$\\mu$m and are analyzed by taking into account the apparent formal\narea efficiency, the distribution $\\rho$, and the slopes in the corresponding\nFN plot. Finally, we remark that our results from numerical solution of\nLaplace's equation, for an array of conducting nano-emitters with uniform apex\nradii $50$ nm but different local height, supports our theoretical assumptions\nand could used in orthodox CFE experiments to test our predictions."
    },
    {
        "anchor": "Nanosize confinement induced enhancement of spontaneous polarization in\n  a ferroelectric nanowire: We theoretically showed that the spontaneous polarization in ferroelectric\n(FE) nanowires (NWs) can be considerably enhanced due to the nanosize\nconfinement by the first-principles calculations. The spontaneous polarization\nalong the wire direction in a fully-relaxed PbTiO3 NW with 1.8 nm diameter is\n1.26 times higher than that of bulk counterpart. The tension induced by NW\nsurface curvature counteracts the near-surface depolarizing effect and\nmeanwhile leads to the unusual enhancement of spontaneous polarization. These\nfindings indicated that FE NWs can be promising in the applications of\nnanodevices.",
        "positive": "Curie temperature versus hole concentration in field-effect structures\n  of Ga1-xMnxAs: The Curie temperature TC is investigated as a function of the hole\nconcentration p in thin films of ferromagnetic semiconductor (Ga,Mn)As. The\nmagnetic properties are probed by transport measurements and p is varied by the\napplication of an external electric field in a field-effect transistor\nconfiguration. It is found that TC is proportional to p^{\\gamma}, where the\nexponent \\gamma = 0.19 \\pm 0.02 over a wide range of Mn compositions and\nchannel thicknesses. The magnitude of gamma is reproduced by a p-d Zener model\ntaking into account nonuniform hole distribution along the growth direction,\ndetermined by interface states and the applied gate electric fields."
    },
    {
        "anchor": "Electronic, structural, and magnetic properties of LaMnO$_3$ phase\n  transition at high temperature: We develop a procedure to determine the portion of exact Hartree-Fock\nexchange interaction contained in a hybrid density functional to treat the\nrange of electronic correlation governing the physics of a system as a function\nof a thermodynamical parameter. This includes systems that depend on physical\nparameters accessible to experiment (i.e., temperature, pressure, composition,\netc.) or those composed of two or more materials such as heterostructures and\ninterfaces. This approach is applied to LaMnO$_3$ where for the first time we\nare able to simulate the high temperature insulator-to-metal transition (IMT)\nand observe a half-metallic orbital disorder ferromagnetic state using density\nfunctional theory. In particular, we show that the softening of the\n\\textit{Q$_2$} Jahn-Teller mode plays a central role in driving the IMT. These\nfindings are likely to motivate the investigation of heterostructures and bulk\nmaterials that contain a range of electronic correlation in similar material\nsystems.",
        "positive": "Scanning tunneling microscopy and kinetic Monte Carlo investigation of\n  Cesium superlattices on Ag(111): Cesium adsorption structures on Ag(111) were characterized in a\nlow-temperature scanning tunneling microscopy experiment. At low coverages,\natomic resolution of individual Cs atoms is occasionally suppressed in regions\nof an otherwise hexagonally ordered adsorbate film on terraces. Close to step\nedges Cs atoms appear as elongated protrusions along the step edge direction.\nAt higher coverages, Cs superstructures with atomically resolved hexagonal\nlattices are observed. Kinetic Monte Carlo simulations model the observed\nadsorbate structures on a qualitative level."
    },
    {
        "anchor": "Fingerprints of hot-phonon physics in time-resolved correlated quantum\n  lattice dynamics: The time dynamics of the energy flow from electronic to lattice degrees of\nfreedom in pump-probe setups could be strongly affected by the presence of a\nhot-phonon bottleneck, which can sustain longer coherence of the optically\nexcited electronic states. Recently, hot-phonon physics has been experimentally\nobserved and theoretically described in MgB$_2$, the electron-phonon based\nsuperconductor with $T_{\\rm c}\\approx 39$ K. By employing a combined ab-initio\nand quantum-field-theory approach and by taking MgB$_2$ as an example, here we\npropose a novel path for revealing the presence and characterizing the\nproperties of hot phonons through a direct analysis of the information encoded\nin the lattice inter-atomic correlations. Such method exploits the underlying\nsymmetry of the $E_{2g}$ hot modes characterized by a out-of-phase in-plane\nmotion of the two boron atoms. Since hot phonons occur typically at\nhigh-symmetry points of the Brillouin zone, with specific symmetries of the\nlattice displacements, the present analysis is quite general and it could aid\nin revealing the hot-phonon physics in other promising materials, such as\ngraphene, boron nitride, or black phosphorus.",
        "positive": "Type-II Dirac fermions in the PtSe$_2$ class of transition metal\n  dichalcogenides: Recently, a new \"type-II\" Weyl fermion, which exhibits exotic phenomena such\nas angle-dependent chiral anomaly, was discovered in a new phase of matter\nwhere electron and hole pockets contact at isolated Weyl points. [Nature\n\\textbf{527}, 495 (2015)] This raises an interesting question whether its\ncounterpart, i.e., type-II \\textit{Dirac} fermion, exists in real materials.\nHere, we predict the existence of symmetry-protected type-II Dirac fermions in\na class of transition metal dichalcogenide materials. Our first-principles\ncalculations on PtSe$_2$ reveal its bulk type-II Dirac fermions which are\ncharacterized by strongly tilted Dirac cones, novel surface states, and exotic\ndoping-driven Lifshitz transition. Our results show that the existence of\ntype-II Dirac fermions in PtSe$_2$-type materials is closely related to its\nstructural $P\\bar{3}m1$ symmetry, which provides useful guidance for the\nexperimental realization of type-II Dirac fermions and intriguing physical\nproperties distinct from those of the standard Dirac fermions known before."
    },
    {
        "anchor": "Evidence of random magnetic anisotropy in ferrihydrite nanoparticles\n  based on analysis of statistical distributions: We show that the magnetic anisotropy energy of antiferromagnetic ferrihydrite\ndepends on the square root of the nanoparticles volume, using a method based on\nthe analysis of statistical distributions. The size distribution was obtained\nby transmission electron microscopy, and the anisotropy energy distributions\nwere obtained from ac magnetic susceptibility and magnetic relaxation. The\nsquare root dependence corresponds to random local anisotropy, whose average is\ngiven by its variance, and can be understood in terms of the recently proposed\nsingle phase homogeneous structure of ferrihydrite.",
        "positive": "Orbital-Energy Splitting in Anion Ordered Ruddlesden-Popper Halide\n  Perovskites for Tunable Optoelectronic Applications: The electronic orbital characteristics at the band edges plays an important\nrole in determining the electrical, optical and defect properties of perovskite\nphotovoltaic materials. It is highly desirable to establish the relationship\nbetween the underlying atomic orbitals and the optoelectronic properties as a\nguide to maximize the photovoltaic performance. Here, using first-principles\ncalculations and taking anion ordered Ruddlesden-Popper (RP) phase halide\nperovskites Cs$_{n+1}$Ge$_n$I$_{n+1}$Cl$_{2n}$ as an example, we demonstrate\nhow to rationally optimize the optoelectronic properties (e.g., band gap,\ntransition dipole matrix elements, carrier effective masses, band width)\nthrough a simple band structure parameter. Our results show that reducing the\nsplitting energy $|\\Delta c|$ of p orbitals of B-site atom can effectively\nreduce the band gap and carrier effective masses while greatly improving the\noptical absorption in the visible region. Thereby, the orbital-property\nrelationship with $\\Delta c$ is well established through biaxial compressive\nstrain. Finally, it is shown that this approach can be reasonably extended to\nseveral other non-cubic halide perovskites with similar p orbitals\ncharacteristics at the conduction band edges. Therefore, we believe that our\nproposed orbital engineering approach provides atomic-level guidance for\nunderstanding and optimizing the device performance of layered perovskite solar\ncells."
    },
    {
        "anchor": "Variety of magnetic topological phases in the\n  (MnBi$_2$Te$_4$)(Bi$_2$Te$_3$)$_m$ family: Quantum states of matter combining non-trivial topology and magnetism attract\na lot of attention nowadays; the special focus is on magnetic topological\ninsulators (MTIs) featuring quantum anomalous Hall and axion insulator phases.\nFeasibility of many novel phenomena that \\emph{intrinsic} magnetic TIs may host\ndepends crucially on our ability to engineer and efficiently tune their\nelectronic and magnetic structures. Here, using angle- and spin-resolved\nphotoemission spectroscopy along with \\emph{ab initio} calculations we report\non a large family of intrinsic magnetic TIs in the homologous series of the van\nder Waals compounds (MnBi$_2$Te$_4$)(Bi$_2$Te$_3$)$_m$ with $m=0, ..., 6$.\nMagnetic, electronic and, consequently, topological properties of these\nmaterials depend strongly on the $m$ value and are thus highly tunable. The\nantiferromagnetic (AFM) coupling between the neighboring Mn layers strongly\nweakens on moving from MnBi2Te4 (m=0) to MnBi4Te7 (m=1), changes to\nferromagnetic (FM) one in MnBi6Te10 (m=2) and disappears with further increase\nin m. In this way, the AFM and FM TI states are respectively realized in the\n$m=0,1$ and $m=2$ cases, while for $m \\ge 3$ a novel and hitherto-unknown\ntopologically-nontrivial phase arises, in which below the corresponding\ncritical temperature the magnetizations of the non-interacting 2D ferromagnets,\nformed by the \\MBT\\, building blocks, are disordered along the third direction.\nThe variety of intrinsic magnetic TI phases in\n(MnBi$_2$Te$_4$)(Bi$_2$Te$_3$)$_m$ allows efficient engineering of functional\nvan der Waals heterostructures for topological quantum computation, as well as\nantiferromagnetic and 2D spintronics.",
        "positive": "Solid-phase silicon homoepitaxy via shear-induced amorphization and\n  recrystallization: The development of epitaxy techniques for localized growth of crystalline\nsilicon nanofilms and nanostructures has been crucial to recent advances in\nelectronics and photonics. A precise definition of the crystal growth location,\nhowever, requires elaborate pre-epitaxy processes for substrate patterning. Our\nmolecular dynamics simulations reveal that homoepitaxial silicon nanofilms can\nbe directly deposited by a crystalline silicon tip rubbing against the\nsubstrate, thus enabling geometrically controlled crystal growth with no need\nfor substrate pre-patterning. We name this solid-phase epitaxial growth\ntriboepitaxy as it solely relies on shear-induced amorphization and\nrecrystallization that occur even at low temperature at the sliding interface\nbetween two silicon crystals. The interplay between the two concomitant,\nshear-induced processes is responsible for the formation of an amorphous\nsliding interface with constant nanometric thickness. If the two elastically\nanisotropic crystals slide along different crystallographic orientations, the\namorphous layer can move unidirectionally perpendicular to the sliding plane,\ncausing the crystal with lowest elastic energy per atom to grow at the expenses\nof the other crystal. As triboepitaxial growth is governed by the shear elastic\nresponse of the two crystals along the sliding direction, it can be implemented\nas a mechanical scanning-probe lithography method in which epitaxial growth is\ncontrolled by tuning the crystallographic misorientation between tip and\nsubstrate, the tip's size or the normal force. These results suggest a\nradically new way to conceive nanofabrication techniques that are based on\ntribologically induced materials transformations."
    },
    {
        "anchor": "Families of superhard crystalline carbon allotropes induced via\n  cold-compressed graphite and nanotubes: We report a general scheme to systematically construct two classes of\nstructural families of superhard sp3 carbon allotropes of cold compressed\ngraphite through the topological analysis of odd 5+7 or even 4+8 membered\ncarbon rings stemmed from the stacking of zigzag and armchair chains. Our\nresults show that the previously proposed M, bct-C4, W and Z allotropes belong\nto our currently proposed families and that depending on the topological\narrangement of the native carbon rings numerous other members are found that\ncan help us understand the structural phase transformation of cold-compressed\ngraphite and carbon nanotubes (CNTs). In particular, we predict the existence\nof two simple allotropes, R- and P-carbon, which match well the experimental\nX-ray diffraction patterns of cold-compressed graphite and CNTs, respectively,\ndisplay a transparent wide-gap insulator ground state and possess a large\nVickers hardness comparable to diamond.",
        "positive": "Charge ordering in charge-compensated $Na_{0.41}CoO_2$ by oxonium ions: Charge ordering behavior is observed in the crystal prepared through the\nimmersion of the $Na_{0.41}CoO_2$ crystal in distilled water. Discovery of the\ncharge ordering in the crystal with Na content less than 0.5 indicates that the\nimmersion in water brings about the reduction of the\n  $Na_{0.41}CoO_2$. The formal valence of Co changes from +3.59 estimated from\nthe\n  Na content to +3.5, the same as that in $Na_{0.5}CoO_2$. The charge\ncompensation is confirmed to arise from the intercalation of the oxonium ions\nas occurred in the superconducting sodium cobalt oxide\nbilayer-hydrate.\\cite{takada1}\n  The charge ordering is the same as that observed in $Na_{0.5}CoO_2$. It\nsuggests that the Co valence of +3.5 is necessary for the charge ordering."
    },
    {
        "anchor": "Mechanism of ferroelectric thin films self-polarization phenomenon: In present work we calculated the three components of polarization in\nphenomenological theory framework by consideration of three Euler-Lagrange\nequations, which include mismatch effect and influence of misfit dislocations,\nsurface tension and depolarization field. These equations were solved with the\nhelp of variational method proposed by us earlier. This approach lead to the\nfree energy in the form of algebraic equation of different powers of\npolarization components with the coefficients dependent on film thickness,\nmismatch effect, temperature and other parameters. Several new terms\nproportional to misfit strain appeared in the free energy expression: built-in\nelectric field normal to the surface originated from piezoelectricity in\nvicinity of surface even in the cubic symmetry of bulk ferroelectrics,\nrenormalization of bulk transition temperature via electrostriction, odd powers\nof normal to the surface component of polarization. The obtained free energy\nmade it possible to calculate all properties of the film by conventional\nprocedure of minimization. It was shown that in both cases self-polarized phase\ndoes exist in definite regions of aforementioned coordinates, its nature being\nmismatch effect. The calculations of pyroelectric coefficient and dielectric\npermittivity dependencies on temperature, strain and thickness had shown the\nunusual behaviour of these quantities, e.g. existence of pyroelectricity at\nthicknesses less than critical one for ferroelectric-paraelectric phase\ntransition.",
        "positive": "Semiconducting nonperovskite ferroelectric oxynitride designed ab initio: Recent discovery of HfO2-based and nitride-based ferroelectrics that are\ncompatible to the semiconductor manufacturing process have revitalized the\nfield of ferroelectric-based nanoelectronics. Guided by a simple design\nprinciple of charge compensation and density functional theory calculations, we\ndiscover HfO2-like mixed-anion materials, TaON and NbON, can crystallize in the\npolar Pca21 phase with a strong thermodynamic driving force to adopt anion\nordering spontaneously. Both oxynitrides possess large remnant polarization,\nlow switching barriers, and unconventional negative piezoelectric effect,\nmaking them promising piezoelectrics and ferroelectrics. Distinct from HfO2\nthat has a wide band gap, both TaON and NbON can absorb visible light and have\nhigh charge carrier mobilities, suitable for ferroelectric photovoltaic and\nphotocatalytic applications. This new class of multifunctional nonperovskite\noxynitride containing economical and environmentally benign elements offer a\nplatform to design and optimize high-performing ferroelectric semiconductors\nfor integrated systems."
    },
    {
        "anchor": "Registry dependent potential for interfaces of gold with graphitic\n  systems: We present a semi-anisotropic interfacial potential (SAIP) designed to\nclassically describe the interaction between gold and two-dimensional (2D)\ncarbon allotropes such as graphene, fullerenes, or hydrocarbon molecules. The\npotential is able to accurately reproduce dispersion corrected density\nfunctional theory (DFT+D3) calculations performed over selected configurations:\na flat graphene sheet, a benzene molecule, and a C$_{60}$ fullerene,\nphysisorbed on the Au(111) surface. The effects of bending and of hydrogen\npassivation on the potential terms are discussed. The presented SAIP potential\nprovides a noticeable improvement in the state-of-the-art description of Au-C\ninterfaces. Also, its functional form is suitable to describe the interfacial\ninteraction between other 2D and bulk materials.",
        "positive": "Structural and Electronic Properties of Hybrid Perovskites for\n  High-Efficiency Thin-Film Photovoltaics from First-Principles: The performance of perovskite solar cells recently exceeded 15%\nsolar-to-electricity conversion efficiency for small-area devices. The\nfundamental properties of the active absorber layers, hybrid organic-inorganic\nperovskites formed from mixing metal and organic halides [\\textit{e.g.}\n(NH$_4$)PbI$_3$ and (CH$_3$NH$_3$)PbI$_3$], are largely unknown. The materials\nare semiconductors with direct band gaps at the boundary of the first Brillouin\nzone. The calculated dielectric response and band gaps show an orientation\ndependence, with a low barrier for rotation of the organic cations. Due to the\nelectric dipole of the methylammonium cation, a photoferroic effect may be\naccessible, which could enhance carrier collection."
    },
    {
        "anchor": "Electronic structure of Gd pnictides: A computational study of the electronic structure and magnetic properties of\nGd-pnictides is reported. The calculations were performed using a\nfull-potential linear muffin-tin orbital (LMTO) method within the so-called\nLSDA+U approach, which adds Hubbard-U correlation effects to specified narrow\nbands in a mean-field approach to the local spin density approximation (LSDA).\nHere both the Gd 4f and 5d states are subject to such corrections. The U(f)\nvalues were determined semi-empirically by using photo-emission and inverse\nphotoemission data for GdP, GdAs, GdSb and GdBi. In contrast to U(f) which\nrepresents narrow band physics, U(d) represents a quasiparticle self-energy\ncorrection of the LSDA gap underestimate. The U(d) value was adjusted using\noptical absorption data for semiconducting GdN above its Curie temperature.\nBelow the Curie temperature, however, in the ferromagnetic state, the gap\nbecomes almost zero. The other Gd pnictides are found to have a small overlap\nof the conduction band at the X point and the valence band at the Gamma point\nin the majority-spin channel. A small gap opens in the spin-minority channel of\nGdP and GdAs, which are thus half-metallic. This spin-minority gap closes in\nsemimetallic GdSb and GdBi. While GdN is found to be ferromagnetic, the other\nGd-pnictides are found to be antiferromagnetic, with ordering along [111]. From\ncalculations with different magnetic configurations, a Heisenberg model with\nfirst and second nearest neighbor exchange parameters is extracted. The\nHeisenberg model is then used to predict Curie-Weiss and N'eel temperatures and\ncritical magnetic fields within mean field and compared with experimental data.\nThe trends are found to be in good agreement with the experimental data.",
        "positive": "Tensile testing of cylindrical multi-shell Cu nanowire: We have simulated the tensile testing of cylindrical multi-shell Cu nanowire.\nElongated cylindrical multi-shell Cu nanowire was transformed into a pentagonal\nstructure. Pentagonal nanowires are composed of a central atomic strand and\npentagonal tubes made of five-times-folded <110>{100} sheets."
    },
    {
        "anchor": "Electric Field Induced Transformation of Magnetic Domain Structure in\n  Magnetoelectric Iron Garnet Films: The room temperature magnetoelectric effect was observed in epitaxial iron\ngarnet films that appeared as magnetic domain wall motion induced by electric\nfield. The films grown on gadolinium-gallium garnet substrates with various\ncrystallographic orientations were examined. The effect was observed in (210)\nand (110) films and was not observed in (111) films. Dynamic observation of the\ndomain wall motion in 400 V voltage pulses gave the value of domain wall\nvelocity in the range 30-50 m/s. The same velocity was achieved in magnetic\nfield pulse about 50 Oe.",
        "positive": "Surface oxidation and thermoelectric properties of indium-doped tin\n  telluride nanowires: The recent discovery of excellent thermoelectric properties and topological\nsurface states in SnTe-based compounds has attracted extensive attention in\nvarious research areas. Indium doped SnTe is of particular interest because,\ndepending on the doping level, it can either generate resonant states in the\nbulk valence band leading to enhanced thermoelectric properties, or induce\nsuperconductivity that coexists with topological states. Here we report on the\nvapor deposition of In-doped SnTe nanowires and the study of their surface\noxidation and thermoelectric properties. The nanowire growth is assisted by Au\ncatalysts, and their morphologies vary as a function of substrate position and\ntemperature. Transmission electron microscopy characterization reveals the\nformation of amorphous surface in single crystalline nanowires. X-ray\nphotoelectron spectroscopy studies suggest that the nanowire surface is\ncomposed of In2O3, SnO2, Te and TeO2 which can be readily removed by argon ion\nsputtering. Exposure of the cleaned nanowires to atmosphere yields rapid\noxidation of the surface within only one minute. Characterizations of\nelectrical conductivity {\\sigma}, thermopower S, and thermal conductivity\n\\k{appa} were performed on the same In-doped nanowire which shows suppressed\n{\\sigma} and \\k{appa} but enhanced S yielding an improved thermoelectric figure\nof merit ZT than the undoped SnTe."
    },
    {
        "anchor": "Thermal expansion and the equation of state of Ir and Rh: The simplest anharmonic characteristics of Ir and Rh are discussed in the\nframework of a previously developed simple pseudopotential model which\ndescribes the elastic moduli, phonon spectra and the lattice heat capacity in\nthe harmonic approximation of these metals succesfully. The microscopic\nGruneisen parameters, the dependences of the elastic moduli on pressure, the\ncoefficient of thermal expansion and the equations of state at the finite\ntemperatures have been calculated. The ab initio calculations of the\nenergy-band structure and the equation of state for Ir at T=0 have been done to\ntest the model for adequacy at high pressures. The values of different\ncontributions (zero-point oscillations, quasiharmonic, etc.) in the considered\nthermodynamic characteristics of Ir and Rh are discussed.",
        "positive": "Spin-polarized electronic structure of the core-shell ZnO/ZnO:Mn\n  nanowires probed by x-ray absorption and emission spectroscopy: The combination of x-ray spectroscopy methods complemented with theoretical\nanalysis unravels the coexistence of paramagnetic and antiferromagnetic phases\nin the Zn_0.9Mn_0.1O shell deposited onto array of wurtzite ZnO nanowires. The\nshell is crystalline with orientation toward the ZnO growth axis, as\ndemonstrated by X-ray linear dichroism. EXAFS analysis confirmed that more than\n90% of Mn atoms substituted Zn in the shell while fraction of secondary phases\nwas below 10%. The value of manganese spin magnetic moment was estimated from\nthe Mn K{\\beta} X-ray emission spectroscopy to be 4.3{\\mu}B which is close to\nthe theoretical value for substitutional Mn_Zn. However the analysis of L_2,3\nx-ray magnetic circular dichroism data showed paramagnetic behaviour with\nsaturated spin magnetic moment value of 1.95{\\mu}B as determined directly from\nthe spin sum rule. After quantitative analysis employing atomic multiplet\nsimulations such difference was explained by a coexistence of paramagnetic\nphase and local antiferromagnetic coupling of Mn magnetic moments. Finally,\nspin-polarized electron density of states was probed by the spin-resolved Mn\nK-edge XANES spectroscopy and consequently analyzed by band structure\ncalculations."
    },
    {
        "anchor": "Identification of a Novel \"Fishbone\" Structure in the Dendritic Growth\n  of Columnar Ice Crystals: Ice crystals growing in highly supersaturated air at temperatures near -5 C\nexhibit a distinctive, nonplanar dendritic morphology that has not been\npreviously documented or explained. We examine this structure and identify its\nmost prominent features in relation to the ice crystal lattice. Developing a\nfull 3D numerical model that reproduces this robust morphology will be an\ninteresting challenge in understanding diffusion-limited crystal growth in the\npresence of highly anisotropic surface attachment kinetics.",
        "positive": "Microsegregation and dendritic growth mode of Al-5wt%Cu alloy based on\n  non-equilibrium mush zone model: The microsegregation and dendritic growth mode of Al-5wt%Cu alloy was\ninvestigated. In the early solidification stage, the crystal growth mode of\ninterrupted growth and periodic boundary trapping will happen, which results in\nthe segregationless dendritic grains. Microsegregation only exists at the final\nsolidification stage with extremely tiny residual melt fraction. In the tiny\nresidual melt zone, the diffusion of solute from the enriched boundary layer to\nthe residual melt and the convergence of enriched boundaries produce the final\nmicrosegregation."
    },
    {
        "anchor": "Structural, Electronic and Elastic Properties of zincblende III-Arsenide\n  Binary Compounds: First-Principles Study: First-principles calculations were performed, and the results from the study\nof structural, electronic and elastic properties of zincblende III-arsenide\nbinary compounds (BAs, AlAs, GaAs and InAs) are presented. These properties\nhave been calculated using an ab initio pseudopotential method based on density\nfunctional theory (DFT) with the local density approximation (LDA) for the\nexchange-correlation potential. The results obtained for the calculated\nproperties have been compared with experimental data and other computational\nworks. It has also been found that our results with LDA are in good agreement\nwith other computational work wherever these are available.",
        "positive": "Nearly Free Electron States in Graphene Nanoribbon Superlattices: Nearly free electron (NFE) state is an important kind of unoccupied state in\nlow dimensional systems. Although it is intensively studied, a clear picture on\nits physical origin and its response behavior to external perturbations is\nstill not available. Our systematic first-principles study based on graphene\nnanoribbon superlattices suggests that there are actually two kinds of NFE\nstates, which can be understood by a simple Kronig-Penney potential model. An\natom-scattering-free NFE transport channel can be obtained via electron doping,\nwhich may be used as a conceptually new field effect transistor."
    },
    {
        "anchor": "Spin-orbit-coupling induced domain-wall resistance in diffusive\n  ferromagnets: We investigate diffusive transport through a number of domain wall (DW)\nprofiles of the important magnetic alloy Permalloy taking into account\nsimultaneously noncollinearity, alloy disorder, and spin-orbit coupling fully\nquantum mechanically, from first principles. In addition to observing the known\neffects of magnetization mistracking and anisotropic magnetoresistance, we\ndiscover a not-previously identified contribution to the resistance of a DW\nthat comes from spin-orbit-coupling-mediated spin-flip scattering in a textured\ndiffusive ferromagnet. This adiabatic DW resistance, which should exist in all\ndiffusive DWs, can be observed by varying the DW width in a systematic fashion\nin suitably designed nanowires.",
        "positive": "Formation energy puzzle in intermetallic alloys: Random phase\n  approximation fails to predict accurate formation energies: We performed density functional calculations to estimate the formation\nenergies of intermetallic alloys. We used two semilocal approximations, the\ngeneralized gradient approximation (GGA) by Perdew-Burke-Ernzerhof (PBE) and\nthe strongly constrained and appropriately normed (SCAN) meta-GGA. In addition,\nwe utilized two nonlocal DFT functionals, the hybrid HSE06, and the\nstate-of-the-art random phase approximation (RPA). The nonlocal functionals\nsuch as HSE06 and RPA yield accurate formation energies of binary alloys with\ncompletely-filled d-band metals, where semilocal functionals underperform. The\naccuracy at the nonlocal functionals is greatly reduced when a partially-filled\nd-band metal is present in an alloy, while PBE-GGA outperforms in these cases.\nWe show that the accurate prediction of formation energies by any DFT method\ndepends on its ability to predict the accurate electronic properties, e.g.,\nvalence d-band contribution to the density of states (DOS). The SCAN meta-GGA\noften corrects the PBE-DOS, however, it does not provide accurate formation\nenergies compared to PBE. This is assumed to be due to the lack of proper error\ncancellation that should be expected due to the similar bulk nature of both\nalloys and their constituents, which may improve with the modification of\nmeta-GGA ingredients. RPA yields too negative formation energies of alloys with\npartially-filled d-band metals. RPA results can be corrected by restoring the\nexchange-correlation kernel, thereby improving the short-range\nelectron-electron correlation in metallic densities."
    },
    {
        "anchor": "Multiple strain-induced phase transitions in LaNiO3 thin films: Strain effects on epitaxial thin films of LaNiO3 grown on different single\ncrystalline substrates are studied by Raman scattering and first-principles\nsimulation. New Raman modes, not present in bulk or fully-relaxed films, appear\nunder both compressive and tensile strains, indicating symmetry reductions.\nInterestingly, the Raman spectra and the underlying crystal symmetry for\ntensile and compressively strained films are different. Extensive mapping of\nLaNiO3 phase stability is addressed by simulations, showing that a variety of\ncrystalline phases are indeed stabilized under strain which may impact the\nelectronic orbital hierarchy. The calculated Raman frequencies reproduce the\nprincipal features of the experimental spectra, supporting the validity of the\nmultiple strain-driven structural transitions predicted by the simulations.",
        "positive": "Earthquake-like dynamics in ultrathin magnetic film: We study the motion of a domain wall on an ultrathin magnetic film using the\nmagneto-optical Kerr effect (MOKE). At tiny magnetic fields, the wall creeps\nonly via thermal activation over the pinning centers present in the sample. Our\nresults show that this creep dynamics is highly intermittent and correlated. A\nlocalized instability triggers a cascade, akin to aftershocks following a large\nearthquake, where the pinned wall undergoes large reorganizations in a compact\nactive region for a few seconds. Surprisingly, the size and shape of these\nreorganizations display the same scale-free statistics of the depinning\navalanches in agreement with the quenched Kardar-Parisi-Zhang universality\nclass."
    },
    {
        "anchor": "Analysis of single and composite structural defects in pure amorphous\n  silicon: a first-principles study: The structural and electronic properties of amorphous silicon ($a$-Si) are\ninvestigated by first-principles calculations based on the density-functional\ntheory (DFT), focusing on the intrinsic structural defects. By simulated\nmelting and quenching of a crystalline silicon model through the Car-Parrinello\nmolecular dynamics (CPMD), we generate several different $a$-Si samples, in\nwhich three-fold ($T_3$), five-fold ($T_5$), and anomalous four-fold ($T_{4a}$)\ndefects are contained. Using the samples, we clarify how the disordered\nstructure of $a$-Si affects the characters of its density of states (DOS). We\nsubsequently study the properties of defect complexes found in the obtained\nsamples, including one that comprises three $T_5$ defects, and we show the\nconditions for the defect complexes to be energetically stable. Finally, we\ninvestigate the hydrogen passivation process of the $T_5$ defects in $a$-Si and\nshow that the hydrogenation of $T_5$ is an exothermic reaction and that the\nactivation energy for a H$_2$ molecule to passivate two $T_5$ sites is\ncalculated to be 1.05 eV.",
        "positive": "Effect of electron-phonon interactions on Raman line at ferromagnetic\n  ordering: The theory of Raman scattering in half-metals by optical phonons interacting\nwith conduction electrons is developed. We evaluate the effect of\nelectron-phonon interactions at ferromagnetic ordering in terms of the\nBoltzmann equation for carriers. The chemical potential is found to decrease\nwith temperature decreasing. Both the linewidth and frequency shift exhibit a\ndependence on temperature."
    },
    {
        "anchor": "Neutron-Irradiation Induced Magnetization and Persistent Defects at High\n  Temperatures in Graphite: Structural as well as magnetization studies have been carried out on graphite\nsamples irradiated by neutrons over 50 years in the CIRUS research reactor at\nTrombay. Neutron diffraction studies reveal that the defects in irradiated\ngraphite samples are not well annealed and remain significant up to high\ntemperatures much greater than 653 K where the Wigner energy is completely\nreleased. We infer that the remnant defects may be intralayer Frenkel defects,\nwhich do not store large energy, unlike the interlayer Frenkel defects that\nstore the Wigner energy. Magnetization studies on the irradiated graphite show\nferromagnetic behavior even at 300 K and a large additional paramagnetic\ncontribution at 5 K. Ab-initio calculations based on the spin-polarized\ndensity-functional theory show that the magnetism in defected graphite is\nessentially confined on to a single 2-coordinated carbon atom that is located\naround a vacancy in the hexagonal layer.",
        "positive": "Density dependence of elastic properties of graphynes: Graphyne is a two-dimensional carbon allotrope of graphene. Its structure is\ncomposed of aromatic rings and/or carbon-carbon bonds connected by one or more\nacetylene chains. As some graphynes present the most of the excellent\nproperties of graphene and non-null bandgap, they have been extensively\nstudied. Recently, Kanegae and Fonseca reported calculations of four elastic\nproperties of 70 graphynes, ten members of the seven families of graphynes\n[Carbon Trends 7, 100152 (2022)]. They showed that the acetylene chain length\ndependence of these properties can be simply modelled by a serial association\nof springs. Here, based on those results, we present the density dependence of\nthese properties and show that the elastic moduli, $E$, of graphyne are less\ndependent on density, $\\rho$, than porous cellular materials with an exponent\nof $E \\sim \\rho^{n}$, smaller than 2. We discuss the results in terms of the\nshape of the pores of the graphyne structures."
    },
    {
        "anchor": "Hidden orbital polarization in diamond, silicon, germanium, gallium\n  arsenide and layered materials: It was previously believed that the Bloch electronic states of non-magnetic\nmaterials with inversion symmetry cannot have finite spin polarizations.\nHowever, since the seminal work by Zhang et al. [Nat. Phys. 10, 387-393 (2014)]\non local spin polarizations of Bloch states in non-magnetic, centrosymmetric\nmaterials, the scope of spintronics has been significantly broadened. Here, we\nshow, using a framework that is universally applicable independent of whether\nhidden spin polarizations are small (e.g., diamond, Si, Ge, and GaAs) or large\n(e.g., MoS2 and WSe2), that the corresponding quantity arising from orbital -\ninstead of spin - degrees of freedom, the hidden orbital polarization, is (i)\nmuch more abundant in nature since it exists even without spin-orbit coupling\nand (ii) more fundamental since the interband matrix elements of the\nsite-dependent orbital angular momentum operator determines the hidden spin\npolarization. We predict that the hidden spin polarization of transition metal\ndichalcogenides is reduced significantly upon compression. We suggest\nexperimental signatures of hidden orbital polarization from photoemission\nspectroscopies and demonstrate that the current-induced hidden orbital\npolarization may play a far more important role than its spin counterpart in\nantiferromagnetic information technology by calculating the current-driven\nantiferromagnetism in compressed silicon.",
        "positive": "Evolution of Weyl orbit and quantum Hall effect in Dirac semimetal\n  Cd3As2: Owing to the coupling between open Fermi arcs on opposite surfaces,\ntopological Dirac semimetals exhibit a new type of cyclotron orbit in the\nsurface states known as Weyl orbit. Here, by lowering the carrier density in\nCd3As2 nanoplates, we observe a crossover from multiple- to single-frequency\nShubnikov-de Haas (SdH) oscillations when subjected to out-of-plane magnetic\nfield, indicating the dominant role of surface transport. With the increase of\nmagnetic field, the SdH oscillations further develop into quantum Hall state\nwith non-vanishing longitudinal resistance. By tracking the oscillation\nfrequency and Hall plateau, we observe a Zeeman-related splitting and extract\nthe Landau level index as well as sub-band number. Different from conventional\ntwo-dimensional systems, this unique quantum Hall effect may be related to the\nquantized version of Weyl orbits. Our results call for further investigations\ninto the exotic quantum Hall states in the low-dimensional structure of\ntopological semimetals."
    },
    {
        "anchor": "Linear-scaling electronic structure theory: Electronic temperature in\n  the Kernel Polynomial Method: Linear-scaling electronic structure methods based on the calculation of\nmoments of the underlying electronic Hamiltonian offer a computationally\nefficient and numerically robust scheme to drive large-scale atomistic\nsimulations, in which the quantum-mechanical nature of the electrons is\nexplicitly taken into account. We compare the kernel polynomial method to the\nFermi operator expansion method and establish a formal connection between the\ntwo approaches. We show that the convolution of the kernel polynomial method\nmay be understood as an effective electron temperature. The results of a number\nof possible kernels are formally examined, and then applied to a representative\ntight-binding model.",
        "positive": "Eshelby-twisted 3D moire superlattices: Twisted bilayers of van der Waals materials have recently attracted great\nattention due to their tunable strongly correlated phenomena. Here, we\ninvestigate the chirality-specific physics in 3D moir\\'e superlattices induced\nby Eshelby twist. Our direct DFT calculations reveal helical rotation leads to\noptical circular dichroism, and chirality-specific nonlinear Hall effect, even\nthough there is no magnetization or magnetic field. Both these phenomena can be\nreversed by changing the structural chirality. This provides a way to\nconstructing chirality-specific materials."
    },
    {
        "anchor": "Molecular Doping of Electrochemically Prepared Triazine-based Carbon\n  Nitride by 2,4,6-Triaminopyrimidine for Improved Photocatalytic Properties: The copolymerization of melamine with 2,4,6-triaminopyrimidine (TAP) in an\nelectrochemical induced polymerization process leads to the formation of\nmolecular doped poly (triazine imide) (PTI). The polymerization is based on the\nelectrolysis of water and evolving radicals during this process. The\nincorporation of TAP is shown by techniques such as elemental analysis, FTIR\nand NMR spectroscopy and powder x-ray diffraction (XRD), and it is shown that\nthe carbon content can be tuned by the variation of the molar ratio of the two\nprecursors. This incorporation of TAP directly influences the electronic\nstructure of PTI and as a result a red-shift can be observed in UV-Vis\nspectroscopy. The smaller bandgap and the increased absorption in the visible\nrange lead to improved photocatalytic properties. In dye degradation\nexperiments it was possible to observe an increase of the rate of the\ndegradation of methylene blue (MB) by a factor of 4 in comparison to undoped\nPTI or 7 if compared to melon.",
        "positive": "Hidden antiferromagnetism on the light-irradiated surface of bulk SrTiO3\n  and at the LaAlO3_SrTiO3 interfaces: We study properties of electrons on illuminated surfaces of SrTiO3 with\ntitanium dxz_dyz and dxy bands for their spectrum. Recently A. F.\nSantander-Syro et al [Nature Materials, 13, 1085 (2014)] found that the dxy\nbands actually comprise two chiral branches with the Kramers degeneracy at the\nzone center lifted in absence of a magnetic moment. From symmetry analysis of\ninstabilities possible in the Fermi liquid with exchange interactions we\nidentified the metallic in-layer state with the concrete antiferromagnetic\nphase and discuss if the same state materializes at conducting LaAlO3_SrTiO3\ninterfaces."
    },
    {
        "anchor": "Dataset of gold nanoparticle sizes and morphologies extracted from\n  literature-mined microscopy images: The factors controlling the size and morphology of nanoparticles have so far\nbeen poorly understood. Data-driven techniques are an exciting avenue to\nexplore this field through the identification of trends and correlations in\ndata. However, for these techniques to be utilized, large datasets annotated\nwith the structural attributes of nanoparticles are required. While\nexperimental SEM/TEM images collected from controlled experiments are reliable\nsources of this information, large-scale collection of these images across a\nvariety of experimental conditions is expensive and infeasible. Published\nscientific literature, which provides a vast source of high-quality figures\nincluding SEM/TEM images, can provide a large amount of data at a lower cost if\neffectively mined. In this work, we develop an automated pipeline to retrieve\nand analyse microscopy images from gold nanoparticle literature and provide a\ndataset of 4361 SEM/TEM images of gold nanoparticles along with automatically\nextracted size and morphology information. The dataset can be queried to obtain\ninformation about the physical attributes of gold nanoparticles and their\nstatistical distributions.",
        "positive": "First-principles investigation of the magnetoelectric properties of\n  Ba$_7$Mn$_4$O$_{15}$: Type-II multiferroics, in which the magnetic order breaks inversion symmetry,\nare appealing for both fundamental and applied research due their intrinsic\ncoupling between magnetic and electrical orders. Using first-principles\ncalculations we study the ground state magnetic behaviour of\nBa$_7$Mn$_4$O$_{15}$ which has been classified as a type-II multiferroic in\nrecent experiments. Our constrained moment calculations with the proposed\nexperimental magnetic structure shows the spontaneous emergence of a polar mode\ngiving rise to an electrical polarisation comparable to other known type-II\nmultiferroics. When the constraints on the magnetic moments are removed, the\nspins self-consistently relax into a canted antiferromagnetic ground state\nconfiguration where two magnetic modes transforming as distinct irreducible\nrepresentations coexist. While the dominant magnetic mode matches well with the\nprevious experimental observations, the second mode is found to possess a\ndifferent character resulting in a non-polar ground state. Interestingly, the\nnon-polar magnetic ground state exhibits a significantly strong linear\nmagnetoelectric coupling comparable to the well-known multiferroic BiFeO$_3$,\nsuggesting strategies to design new linear magnetoelectrics."
    },
    {
        "anchor": "Greener processing of SrFe$_{12}$O$_{19}$ ceramic permanent magnets by\n  two-step sintering: With an annual production amounting to 800 kilotons, ferrite magnets\nconstitute the largest family of permanent magnets in volume, a demand that\nwill only increase as a consequence of the rare-earth crisis. With the global\ngoal of building a climate-resilient future, strategies towards a greener\nmanufacturing of ferrite magnets are of great interest. A new ceramic\nprocessing route for obtaining dense Sr-ferrite sintered magnets is presented\nhere. Instead of the usual sintering process employed nowadays in ferrite\nmagnet manufacturing that demands long dwell times, a shorter two-step\nsintering is designed to densify the ferrite ceramics. As a result of these\nprocesses, dense SrFe$_{12}$O$_{19}$ ceramic magnets with properties comparable\nto state-of-the-art ferrite magnets are obtained. In particular, the\nSrFe$_{12}$O$_{19}$ magnet containing 0.2% PVA and 0.6% wt SiO$_2$ reaches a\ncoercivity of 164 kA/m along with a 93% relative density. A reduction of 31% in\nenergy consumption is achieved in the thermal treatment with respect to\nconventional sintering, which could lead to energy savings for the industry of\nthe order of 7.109 kWh per year.",
        "positive": "From structure mining to unsupervised exploration of atomic octahedral\n  networks: Networks of atom-centered coordination octahedra commonly occur in inorganic\nand hybrid solid-state materials. Characterizing their spatial arrangements and\ncharacteristics is crucial for relating structures to properties for many\nmaterials families. The traditional method using case-by-case inspection\nbecomes prohibitive for discovering trends and similarities in large datasets.\nHere, we operationalize chemical intuition to automate the geometric parsing,\nquantification, and classification of coordination octahedral networks. We find\naxis-resolved tilting trends in ABO$_{3}$ perovskite polymorphs, which assist\nin detecting oxidation state changes. Moreover, we develop a scale-invariant\nencoding scheme to represent these networks, which, combined with\nhuman-assisted unsupervised machine learning, allows us to taxonomize the\ninorganic framework polytypes in hybrid iodoplumbates (A$_x$Pb$_y$I$_z$).\nConsequently, we uncover a violation of Pauling's third rule and the design\nprinciples underpinning their topological diversity. Our results offer a\nglimpse into the vast design space of atomic octahedral networks and inform\nhigh-throughput, targeted screening of specific structure types."
    },
    {
        "anchor": "Spectroscopic determination of hole density in the ferromagnetic\n  semiconductor Ga$_{1-x}$Mn$_{x}$As: The measurement of the hole density in the ferromagnetic semiconductor\nGa$_{1-x}$Mn$_{x}$As is notoriously difficult using standard transport\ntechniques due to the dominance of the anomalous Hall effect. Here, we report\nthe first spectroscopic measurement of the hole density in four\nGa$_{1-x}$Mn$_{x}$As samples ($x=0, 0.038, 0.061, 0.083$) at room temperature\nusing Raman scattering intensity analysis of the coupled plasmon-LO-phonon mode\nand the unscreened LO phonon. The unscreened LO phonon frequency linearly\ndecreases as the Mn concentration increases up to 8.3%. The hole density\ndetermined from the Raman scattering shows a monotonic increase with increasing\n$x$ for $x\\leq0.083$, exhibiting a direct correlation to the observed $T_c$.\nThe optical technique reported here provides an unambiguous means of\ndetermining the hole density in this important new class of ``spintronic''\nsemiconductor materials.",
        "positive": "THz emission from Co/Pt bilayers with varied roughness, crystal\n  structure, and interface intermixing: Femtosecond laser excitation of a Co/Pt bilayer results in the efficient\nemission of picosecond THz pulses. Two known mechanisms for generating THz\nemission are spin-polarized currents through a Co/Pt interface, resulting in\nhelicity-independent electric currents in the Pt layer due to the inverse\nspin-Hall effect and helicity-dependent electric currents at the Co/Pt\ninterface due to the inverse spin-orbit torque effect. Here we explore how\nroughness, crystal structure and intermixing at the Co/Pt interface affect the\nefficiency of the THz emission. In particular, we varied the roughness of the\ninterface, in the range of 0.1-0.4 nm, by tuning the deposition pressure\nconditions during the fabrication of the Co/Pt bilayers. To control the\nintermixing at the Co/Pt interface a 1-2 nm thick CoxPt1-x alloy spacer layer\nwas introduced with various compositions of Co and Pt. Finally, the crystal\nstructure of Co was varied from face centered cubic to hexagonal close packed.\nOur study shows that the roughness of the interface is of crucial importance\nfor the efficiency of helicity-dependent THz emission induced by femtosecond\nlaser pulses. However, it is puzzling that intermixing while strongly enhancing\nthe helicity-independent THz emission had no effect on the helicity-dependent\nTHz emission which is suppressed and similar to the smooth interfaces."
    },
    {
        "anchor": "Work function seen with sub-meV precision through laser photoemission: Electron emission can be utilised to measure the work function of the\nsurface. However, the number of significant digits in the values obtained\nthrough thermionic-, field- and photo-emission techniques is typically just two\nor three. Here, we show that the number can go up to five when angle-resolved\nphotoemission spectroscopy (ARPES) is applied. This owes to the capability of\nARPES to detect the slowest photoelectrons that are directed only along the\nsurface normal. By using a laser-based source, we optimised our setup for the\nslow photoelectrons and resolved the slowest-end cutoff of Au(111) with the\nsharpness not deteriorated by the bandwidth of light nor by Fermi-Dirac\ndistribution. The work function was leveled within $\\pm$0.4 meV at least from\n30 to 90 K and the surface aging was discerned as a meV shift of the work\nfunction. Our study opens the investigations into the fifth significant digit\nof the work function.",
        "positive": "Minimum Vertex-type Sequence Indexingfor Clusters on Square Lattice: An effective indexing scheme for clusters that enables fast structure\ncomparison and congruence check is desperately desirable in the field of\nmathematics, artificial intelligence, materials science, etc. Here we introduce\nthe concept of minimum vertex-type sequence for the indexing of clusters on\nsquare lattice, which contains a series of integers each labeling the vertex\ntype of an atom. The minimum vertex-type sequence is orientation independent,\nand it builds a one-to-one correspondence with the cluster. By using minimum\nvertex-type sequence for structural comparison and congruence check, only one\ntype of data is involved, and the largest amount of data to be compared is n\npairs, n is the cluster size. In comparison with traditional coordinate-based\nmethods and distance-matrix methods, the minimum vertex-type sequence indexing\nscheme has many other remarkable advantages. Furthermore, this indexing scheme\ncan be easily generalized to clusters on other high-symmetry lattices. Our work\ncan facilitate cluster indexing and searching in various situations, it may\ninspire the search of other practical indexing schemes for handling clusters of\nlarge sizes."
    },
    {
        "anchor": "Seeing many-body effects in single- and few-layer graphene: Observation\n  of two-dimensional saddle-point excitons: Significant excitonic effects were observed in graphene by measuring its\noptical conductivity in a broad spectral range including the two-dimensional\n{\\pi}-band saddle-point singularities in the electronic structure. The strong\nelectron-hole interactions manifest themselves in an asymmetric resonance\npeaked at 4.62 eV, which is red-shifted by nearly 600 meV from the value\npredicted by ab-initio GW calculations for the band-to-band transitions. The\nobserved excitonic resonance is explained within a phenomenological model as a\nFano interference of a strongly coupled excitonic state and a band continuum.\nOur experiment also showed a weak dependence of the excitonic resonance in\nfew-layer graphene on layer thickness. This result reflects the effective\ncancellation of the increasingly screened repulsive electron-electron (e-e) and\nattractive electron-hole (e-h) interactions.",
        "positive": "Excitation's lifetime extracted from electron-photon (EELS-CL)\n  nanosecond-scale temporal coincidences: Electron-photon temporal correlations in electron energy loss (EELS) and\ncathodoluminescence (CL) spectroscopies have recently been used to measure the\nrelative quantum efficiency of materials. This combined spectroscopy, named\nCathodoluminescence excitation spectroscopy (CLE), allows the identification of\nexcitation and decay channels which are hidden in average measurements. Here,\nwe demonstrate that CLE can also be used to measure excitation's decay time. In\naddition, the decay time as a function of the excitation energy is accessed, as\nthe energy for each electron-photon pair is probed. We used two well-known\ninsulating materials to characterize this technique, nanodiamonds with\n\\textit{NV$^0$} defect emission and h-BN with a \\textit{4.1 eV} defect\nemission. Both also exhibit marked transition radiations, whose extremely short\ndecay times can be used to characterize the instrumental response function. It\nis found to be typically 2 ns, in agreement with the expected limit of the EELS\ndetector temporal resolution. The measured lifetimes of \\textit{NV$^0$} centers\nin diamond nanoparticles (20 to 40 ns) and \\textit{4.1 eV} defect in h-BN\nflakes ($<$ 2 ns) matches those reported for those materials previously."
    },
    {
        "anchor": "Observation of Magnonic Band Gaps in Magnonic Crystals with\n  Nopnreciprocal Dispersion Relation: An effect of metallization of the magnonic crystal surface on the band gaps\nformation in the spectra of the surface spin wave (SSW) is studied both\ntheoretically and experimentally. The structures under consideration are\none-dimensional magnonic crystals based on yttrium iron garnet with an array of\netched grooves with metal screen on the top of the corrugated surface and\nwithout it. Due to nonreciprocity of propagation of the SSW the shift of band\ngap to higher frequency and from the border of the Brillouin zone in presence\nof conducting overlayer was measured in transmission line experiment. Results\nof numerical calculations and model analysis are in agreement with experimental\ndata and give further insight into origin of the band gap and properties of the\nnonreciprocal SSW in metallized magnonic crystals. This gives positive answer\nto the outstanding question about possibility of detection of magnonic band\ngaps in the spectra of the spin waves with nonreciprocal dispersion in magnonic\ncrystals and creates potential for new applications and improvements of already\nexisting prototype magnonic devices.",
        "positive": "Capturing Multireference Excited States by Constrained DFT: The computation of excited electronic states with commonly employed\n(approximate) methods is challenging, typically yielding states of lower\nquality than the corresponding ground state for a higher computational cost. In\nthis work, we present a mean field method that extends the previously proposed\neXcited Constrained DFT (XCDFT) from single Slater determinants to ensemble\n1-RDMs for computing low-lying excited states. The method still retains an\nassociated computational complexity comparable to a semilocal DFT calculation\nwhile at the same time is capable of approaching states with multireference\ncharacter. We benchmark the quality of this method on well-established test\nsets, finding good descriptions of the electronic structure of multireference\nstates and maintaining an overall accuracy for the predicted excitation\nenergies comparable to semilocal TDDFT."
    },
    {
        "anchor": "Pressure dependence of the Curie temperature in Ni2MnSn Heusler alloy: A\n  first-principles study: The pressure dependence of electronic structure, exchange interactions and\nCurie temperature in ferromagnetic Heusler alloy Ni2MnSn has been studied\ntheoretically within the framework of the density-functional theory. The\ncalculation of the exchange parameters is based on the frozen--magnon approach.\nThe Curie temperature, Tc, is calculated within the mean-field approximation by\nsolving the matrix equation for a multi-sublattice system. In agrement with\nexperiment the Curie temperature increased from 362K at ambient pressure to 396\nat 12 GPa. Extending the variation of the lattice parameter beyond the range\nstudied experimentally we obtained non-monotonous pressure dependence of the\nCurie temperature and metamagnetic transition. We relate the theoretical\ndependence of Tc on the lattice constant to the corresponding dependence\npredicted by the empirical interaction curve. The Mn-Ni atomic interchange\nobserved experimentally is simulated to study its influence on the Curie\ntemperature.",
        "positive": "Perfect absorption by an atomically thin crystal: Optical absorption is one of fundamental light-matter interactions. In most\nmaterials, optical absorption is a weak perturbation to the light. In this\nregime, absorption and emission are irreversible, incoherent processes due to\nstrong damping. Excitons in monolayer transition metal dichalcogenides,\nhowever, interact strongly with light, leading to optical absorption in the\nnon-perturbative regime where coherent re-emission of the light has to be\nconsidered. Between the incoherent and coherent limits, we show that a robust\ncritical coupling condition exists, leading to perfect optical absorption. Up\nto 99.6% absorption is measured in a sub-nanometer thick MoSe2 monolayer placed\nin front of a mirror. The perfect absorption is controlled by tuning the\nexciton-phonon, exciton-exciton, and exciton-photon interactions by\ntemperature, pulsed laser excitation, and a movable mirror, respectively. Our\nwork suggests unprecedented opportunities for engineering exciton-light\ninteractions using two-dimensional atomically thin crystals, enabling novel\nphotonic applications including ultrafast light modulators and sensitive\noptical sensing."
    },
    {
        "anchor": "An effective model for the electronic and optical properties of stanene: The existence of several 2D materials with heavy atoms in their composition\nhas been recently demonstrated. The electronic and optical properties of these\nmaterials can be accurately computed with numerically intensive density\nfunctional theory methods. However, it is desirable to have simple effective\nmodels that can accurately describe these properties at low energies. Here we\npresent an effective model for stanene that is reliable for electronic and\noptical properties for photon energies up to 1.1 eV. For this material, we find\nthat a quadratic model with respect to the lattice momentum is the best suited\nfor calculations based on the bandstructure, even with respect to band warping.\nWe also find that splitting the two spin-z subsectors is a good approximation,\nwhich indicates that the lattice buckling can be neglected in calculations\nbased on the bandstructure. We illustrate the applicability of the model by\ncomputing the linear optical injection rates of carrier and spin densities in\nstanene. Our calculations indicate that an incident circularly polarized\noptical field only excites electrons with spin that matches its helicity.",
        "positive": "Strong anisotropic influence of local-field effects on the dielectric\n  response of \u03b1-MoO3: Dielectric properties of {\\alpha}-MoO3 are investigated by a combination of\nvalence electron-energy loss spectroscopy and ab initio calculation at the\nrandom phase approximation level with the inclusion of local-field effects\n(LFE). A meticulous comparison between experimental and calculated spectra is\nperformed in order to interpret calculated dielectric properties. The\ndielectric function of MoO3 has been obtained along the three axes and the\nimportance of LFE has been shown. In particular, taking into account LFE is\nshown to be essential to describe properly the intensity and position of the\nMo-N2,3 edges as well as the low energy part of the spectrum. A detailed study\nof the energy-loss function in connection with the dielectric response function\nalso shows that the strong anisotropy of the energy-loss function of\n{\\alpha}-MoO3 is driven by an anisotropic influence of LFE. These LFE\nsignificantly dampen a large peak in {\\epsilon}2, but only along the [010]\ndirection. Thanks to a detailed analysis at specific k-points of the orbitals\ninvolved in this transition, the origin of this peak has not only been\nevidenced but a connection between the inhomogeneity of the electron density\nand the anisotropic influence of local-field effects has also been established.\nMore specifically, this anisotropy is governed by a strongly inhomogeneous\nspatial distribution of the empty states. This depletion of the empty states is\nlocalized around the terminal oxygens and accentuates the electron\ninhomogeneity."
    },
    {
        "anchor": "Bright-Exciton Fine Structure and Anisotropic Exchange in CdSe\n  Nanocrystal Quantum Dots: We report on polarization-resolved resonant photoluminescence (PL)\nspectroscopy of bright (spin-1) and dark (spin-2) excitons in colloidal CdSe\nnanocrystal quantum dots. Using high magnetic fields to 33 T, we resonantly\nexcite (and selectively analyze PL from) spin-up or spin-down excitons. At low\ntemperatures (<4K) and above ~10 T, the spectra develop a narrow, circularly\npolarized peak due to spin-flipped bright excitons. Its evolution with magnetic\nfield directly reveals a large (1-2 meV), intrinsic fine structure splitting of\nbright excitons, due to anisotropic exchange. These findings are supported by\ntime-resolved PL studies and polarization-resolved PL from single nanocrystals.",
        "positive": "Solid-state dewetting on curved substrates: Based on the thermodynamic variation to the free energy functional, we\npropose a sharp-interface model for simulating solid-state dewetting of thin\nfilms on rigid curved substrates in two dimensions. This model describes the\ninterface evolution which occurs through surface diffusion-controlled mass\ntransport and contact point migration along the curved substrate. Furthermore,\nthe surface energy anisotropy is easily included into the model, and the\ncontact point migration is explicitly described by the relaxed contact angle\nboundary condition. We implement the mathematical model by a semi-implicit\nparametric finite element method to study several interesting phenomena, such\nas \"small\" particle migration on curved substrates and templated solid-state\ndewetting on a pre-patterned substrate. Based on ample numerical simulations,\nwe demonstrate that, the migration velocity of a \"small\" solid particle is\nproportional to the substrate curvature gradient $\\hat{\\kappa}'$ and inversely\nproportional to the square root of the area of the particle $\\sqrt{A}$, and it\ndecreases when the isotropic Young angle $\\theta_i$ increases. In addition, we\nalso observe four periodic categories of dewetting on a pre-patterned\nsinusoidal substrate. Our approach can provide a convenient and powerful tool\nto exploring how to produce well-organized nanoparticles by making use of\ntemplate-assisted solid-state dewetting."
    },
    {
        "anchor": "Influence of fractional composition of crystallite grains on the dark\n  conductivity in fully crystallized undoped microcrystalline silicon: Improvement in film growth technology requires a knowledge of the correlation\nbetween microstructural and deposition parameters with electrical properties in\nhydrogenated microcrystalline Si films. Our study indicates that fractional\ncompositions of the constituent crystallite grains in fully crystallized\nundoped microcrystalline Si films is a unique microstructural feature that\ndefines the film microstructure and can be well correlated to the electrical\ntransport properties as well.",
        "positive": "On the fraction-dimension migration of self-interstitials in zirconium: MD simulations were conducted to study the self-interstitial migration in\nzirconium. By defining the crystal lattice point, at which more than one atom\nfall in the Wigner-Seitz cell of the lattice point, for the location of\ninterstitial atoms (LSIA), three types of events were identified for LSIA\nmigration: the jump remaining in one <112_0> direction (ILJ), the jump from one\n<112_0> to another <112_0> direction in the same basal plane (OLJ) and the jump\nfrom one basal plane to an adjacent basal plane (OPJ). The occurrence\nfrequencies of the three types were calculated. ILJ was found to be the\ndominant event in the temperature range (300K to 1200K), but the occurrence\nfrequencies of OLJ and OPJ increased with increasing temperature. Although the\nthree types of jumps may not follow Brownian and Arrhenius behavior, on the\nwhole, the migration of the LSIAs tend to be Brownian-like. Moreover, the\nmigration trajectories of LSAs in the hcp basal-plane are not what are observed\nif only conventional one- or two-dimensional migrations exist; rather, they\nexhibit the feature we call fraction-dimensional. Namely, the trajectories are\ncomposed of line segments in <112_0> directions with the average length of the\nline segments varying with the temperature. Using MC simulations, the potential\nkinetic impacts of the fraction-dimensional migration, measured by the average\nnumber of lattice sites visited per jump event n_SPE was analyzed. The\nsignificant differences between the n_SPE value of the fraction-dimensional\nmigration and those of the conventional one- and two-dimensional migrations\nsuggest that the conventional diffusion coefficient, which cannot reflect the\nfeature of fraction-dimensional migration, cannot give an accurate description\nof the underlying kinetics of SIAs in Zr."
    },
    {
        "anchor": "Charge Exchange and Energy Loss of Slow Highly Charged Ions in 1nm Thick\n  Carbon Nanomembranes: Experimental charge exchange and energy loss data for the transmission of\nslow highly charged Xe ions through ultra-thin polymeric carbon membranes are\npresented. Surprisingly, two distinct exit charge state distributions\naccompanied by charge exchange dependent energy losses are observed. The energy\nloss for ions exhibiting large charge loss shows a quadratic dependency on the\nincident charge state indicating that equilibrium stopping force values do not\napply in this case. Additional angle resolved transmission measurements point\non a significant contribution of elastic energy loss. The observations show\nthat regimes of different impact parameters can be separated and thus a\nparticle's energy deposition in an ultra-thin solid target may not be described\nin terms of an averaged energy loss per unit length.",
        "positive": "Mechanical behavior of InP twinning superlattice nanowires: Taper-free InP twinning superlattice (TSL) nanowires with an average twin\nspacing of ~ 13 nm were grown along the zinc-blende close-packed [111]\ndirection using metalorganic vapor phase epitaxy. The mechanical properties and\nfracture mechanisms of individual InP TSL nanowires in tension were ascertained\nby means of in situ uniaxial tensile tests in a transmission electron\nmicroscope. The elastic modulus, failure strain and tensile strength along the\n[111] direction were determined. No evidence of inelastic deformation\nmechanisms was found before fracture, which took place in a brittle manner\nalong the twin boundary. The experimental results were supported by molecular\ndynamics simulations of the tensile deformation of the nanowires that also\nshowed that the fracture of twinned nanowires occurred in the absence of\ninelastic deformation mechanisms by the propagation of a crack from the\nnanowire surface along the twin boundary."
    },
    {
        "anchor": "Theory of domain structure in ferromagnetic phase of diluted magnetic\n  semiconductors near the phase transition temperature: We discuss the influence of disorder on domain structure formation in\nferromagnetic phase of diluted magnetic semiconductors (DMS) of p-type. Using\nanalytical arguments we show the existence of critical ratio $\\nu_{\\rm {cr}}$\nof concentration of charge carriers and magnetic ions such that sample critical\nthickness $L_{\\rm{cr}}$ (such that at $L<L_{\\rm{cr}}$ a sample is monodomain)\ndiverges as $\\nu \\to \\nu_{\\rm {cr}}$. At $\\nu > \\nu_{\\rm {cr}}$ the sample is\nmonodomain. This feature makes DMS different from conventional ordered magnets\nas it gives a possibility to control the sample critical thickness and emerging\ndomain structure period by variation of $\\nu $. As concentration of magnetic\nimpurities grows, $\\nu_{\\rm {cr}}\\to \\infty$ restoring conventional behavior of\nordered magnets. Above facts have been revealed by examination of the\ntemperature of transition to inhomogeneous magnetic state (stripe domain\nstructure) in a slab of finite thickness $L$ of p-type DMS. Our analysis is\ncarried out on the base of homogeneous exchange part of magnetic free energy of\nDMS calculated by us earlier [\\prb, {\\bf 67}, 195203 (2003)].",
        "positive": "Nanostructure determination from the pair distribution function: A\n  parametric study of the INVERT approach: We present a detailed study of the mechanism by which the INVERT method\n[Phys. Rev. Lett. 104, 125501] guides structure refinement of disordered\nmaterials. We present a number of different possible implementations of the\ncentral algorithm and explore the question of algorithm weighting. Our analysis\nincludes quantification of the relative contributions of variance and\nfit-to-data terms during structure refinement, which leads us to study the\nroles of density fluctuations and configurational jamming in the RMC fitting\nprocess. We present a parametric study of the pair distribution function\nsolution space for C60, a-Si and a-SiO2, which serves to highlight the\ndifficulties faced in developing a transferable weighting scheme."
    },
    {
        "anchor": "Thermodynamic and mechanical properties of copper precipitates in\n  alpha-iron from atomistic simulations: The Fe-Cu system has attracted much attention over the last several decades\ndue to its technological importance as a model alloy for Cu steels. In spite of\nthese efforts several aspects of its phase diagram remain unexplained. Here we\nuse atomistic simulations to characterize the polymorphic phase diagram of Cu\nprecipitates in body-centered cubic (BCC) Fe and establish a consistent link\nbetween their thermodynamic and mechanical properties in terms of thermal\nstability, shape, and strength. The size at which Cu precipitates transform\nfrom BCC to a close-packed 9R structure is found to be strongly temperature\ndependent, ranging from approximately 4 nm in diameter (~2,700 atoms) at 200 K\nto about 8 nm (~22,800 atoms) at 700 K. These numbers are in very good\nagreement with the interpretation of experimental data given Monzen et al.\n[Phil. Mag. A 80, 711 (2000)]. The strong temperature dependence originates\nfrom the entropic stabilization of BCC Cu, which is mechanically unstable as a\nbulk phase. While at high temperatures the transition exhibits first-order\ncharacteristics, the hysteresis, and thus the nucleation barrier, vanish at\ntemperatures below approximately 300\\,K. This behavior is explained in terms of\nthe mutual cancellation of the energy differences between core and shell\n(wetting layer) regions of BCC and 9R nanoprecipitates, respectively. The\nproposed mechanism is not specific for the Fe--Cu system but could generally be\nobserved in immiscible systems, whenever the minority component is unstable in\nthe lattice structure of the host matrix. Finally, we also study the\ninteraction of precipitates with screw dislocations as a function of both\nstructure and orientation. The results provide a coherent picture of\nprecipitate strength that unifies previous calculations and experimental\nobservations.",
        "positive": "Anharmonic stabilization of ferrielectricity in CuInP$_2$Se$_6$: Using first-principles calculations and group-theory based models, we study\nthe stabilization of ferrielectricity (FiE) in CuInP$_2$Se$_6$. We find that\nthe FiE ground state is stabilized by a large anharmonic coupling between the\npolar mode and a fully symmetric Raman-active mode. Our results open\npossibilities for controlling the single-step switching barrier for\npolarization by tuning the Raman-active mode. We discuss the implications of\nour findings in the context of designing next-generation optoelectronic devices\nthat can overcome the voltage-time dilemma."
    },
    {
        "anchor": "Alloying, de-alloying and reentrant alloying in (sub-)monolayer growth\n  of Ag on Pt(111): An in-situ nanoscopic investigation of the prototypical surface alloying\nsystem Ag/Pt(111) is reported. The morphology and the structure of the\nultrathin Ag-Pt film is studied using Low Energy Electron Microscopy during\ngrowth at about 800 K. An amazingly rich dynamic behaviour is uncovered in\nwhich stress relieve plays a governing role. Initial growth leads to surface\nalloying with prolonged and retarded nucleation of ad-islands. Beyond 50%\ncoverage de-alloying proceeds, joined by partial segregation of Pt towards the\ncentre of large islands in violent processes. Upon coalescence the irregularly\nshaped vacancy clusters are filled by segregating Pt, which then take a compact\nshape (black spots). As a result at around 85% coverage the strain of the\ninitially pseudo-morphological film is almost completely relieved and\nPt-segregation is at its maximum. Further deposition of Ag leads to transient\nre-entrant alloying and recovery of the pseudo-morphological layer. The black\nspots persist even in/on several layers thick films. Ex-situ atomic force\nmicroscopy data confirm that these are constituted by probably amorphous\nPt(-rich) structures. The (sub-)monolayer films are very much heterogeneous.",
        "positive": "Stabilizing intrinsic defects in SnO$_{2}$: TThe magnetism and electronic structure of Li-doped SnO$_{2}$ are\ninvestigated using first-principles LDA/LDA$+U$ calculations. We find that Li\ninduces magnetism in SnO$_{2}$ when doped at the Sn site but becomes\nnon-magnetic when doped at the O and interstitial sites. The calculated\nformation energies show that Li prefers the Sn site as compared with the O\nsite, in agreement with previous experimental works. The interaction of Li with\nnative defects (Sn V$_\\mathrm{Sn}$ and O V$_\\mathrm{O}$ vacancies) is also\nstudied, and we find that Li not only behaves as a spin polarizer, but also a\nvacancy stabilizer, i.e. Li significantly reduces the defect formation energies\nof the native defects and helps the stabilization of magnetic oxygen vacancies.\nThe electronic densities of states reveals that these systems, where the Fermi\nlevel touches the conduction (valence) band, are non-magnetic\n(magnetic).cancies. The electronic densities of states reveal that those\nsystems, where the Fermi levels touch the conduction (valence) band, are\nnon-magnetic (magnetic)."
    },
    {
        "anchor": "Some theoretical results on semiconductor spherical quantum dots: We use an improved version of the standard effective mass approximation model\nto describe quantum effects in nanometric semiconductor Quantum Dots (QDs).\nThis allows analytic computation of relevant quantities to a very large extent.\nWe obtain, as a function of the QD radius, in precise domains of validity, the\nQD excitonic ground state energy and its Stark and Lamb shifts. Finally, the\nPurcell effect in QDs is shown to lead to potential QD-LASER emitting in the\nrange of visible light.",
        "positive": "A semiclassical Thomas-Fermi model to tune the metallicity of electrodes\n  in molecular simulations: Spurred by the increasing needs in electrochemical energy storage devices,\nthe electrode/electrolyte interface has received a lot of interest in recent\nyears. Molecular dynamics simulations play a proeminent role in this field\nsince they provide a microscopic picture of the mechanisms involved. The\ncurrent state-of-the-art consists in treating the electrode as a perfect\nconductor, precluding the possibility to analyze the effect of its metallicity\non the interfacial properties. Here we show that the Thomas-Fermi model\nprovides a very convenient framework to account for the screening of the\nelectric field at the interface and differenciating good metals such as gold\nfrom imperfect conductors such as graphite. All the interfacial properties are\nmodified by screening within the metal: the capacitance decreases significantly\nand both the structure and dynamics of the adsorbed electrolyte are affected.\nThe proposed model opens the door for quantitative predictions of the\ncapacitive properties of materials for energy storage."
    },
    {
        "anchor": "Planar and Nematic Aerogels: DLCA and Superfluid 3He: We perform cluster aggregation simulations to model the structure of\nanisotropic aerogel. By biasing the diffusion process, we are able to obtain\ntwo distinct types of globally anisotropic aerogel structures which we call\n\"nematic\", with long strands along the anisotropy axis, and \"planar\", with long\nstrands in planes perpendicular to the anisotropy axis. We calculate the\nauto-correlation function, the structure factor, and the angular dependence of\nthe free-path distribution for these samples. The calculated structure factor\nfrom simulated aerogels can be compared with data from small-angle X-ray\nscattering (SAXS) of lab-grown aerogel allowing us to classify the spatial\nstructure of the lab-grown samples. We find that the simulated \"nematic\"\naerogel has a structure factor consistent with lab-grown, axially-compressed\nsilica aerogel while the simulated \"planar\" aerogel has a structure factor\nconsistent with lab-grown \"stretched\" silica aerogel. Unexpectedly, compressing\npreviously isotropic silica aerogel leads to the formation of long strands\nalong the compression axis while stretching silica aerogel leads to formation\nof planes perpendicular to the stretching axis. We discuss the implication of\nthis determination on experiments of superfluid $^3$He in anisotropic aerogel,\nin particular the orbital analog of the spin-flop transition.",
        "positive": "High pressure phases of crystalline tellurium: A study of high pressure solid Te was carried out at room temperature using\nRaman spectroscopy and Density Functional Theory (DFT) calculations. The\nanalysis of the P-dependence of the experi- mental phonon spectrum reveals the\noccurrence of phase transitions at 4 GPa and 8 GPa confirming the high-pressure\nscenario recently proposed. The effects of the incommensurate lattice\nmodulation on the vibrational properties of Te is discussed. DFT calculations\nagree with present and previous experimental data and show the metallization\nprocess at 4 GPa being due to the development of charge-bridges between atoms\nbelonging to adjacent chains. A first-principles study of the stability of the\n4 GPa phase is reported and discussed also in the light of the insurgence of\nlattice modulation."
    },
    {
        "anchor": "Ferroelectricity and multiferroicity in anti-Ruddlesden-Popper\n  structures: Combining ferroelectricity with other properties such as visible light\nabsorption or long-range magnetic order requires the discovery of new families\nof ferroelectric materials. Here, through the analysis of a high-throughput\ndatabase of phonon band structures, we identify a new structural family of\nanti-Ruddlesden-Popper phases A$_4$X$_2$O (A=Ca, Sr, Ba, Eu, X=Sb, P, As, Bi)\nshowing ferroelectric and anti-ferroelectric behaviors. The discovered\nferroelectrics belong to the new class of hyperferroelectrics which polarize\neven under open-circuit boundary conditions. The polar distortion involves the\nmovement of O anions against apical A cations and is driven by geometric\neffects resulting from internal chemical strains. Within this new structural\nfamily, we show that Eu$_4$Sb$_2$O combines coupled ferromagnetic and\nferroelectric order at the same atomic site, a very rare occurrence in\nmaterials physics.",
        "positive": "Computational Investigation of Inverse-Heusler compounds for Spintronics\n  Applications: First-principles calculations of the electronic structure, magnetism and\nstructural stability of inverse-Heusler compounds with the chemical formula\n\\textit{X$_2$YZ} are presented and discussed with a goal of identifying\ncompounds of interest for spintronics. Compounds for which the number of\nelectrons per atom for \\textit{Y} exceed that for \\textit{X} and for which\n\\textit{X} is one of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, or Cu; \\textit{Y} is one of\nTi, V, Cr, Mn, Fe, Co, Ni, Cu, or Zn; and \\textit{Z} is one of Al, Ga, In, Si,\nGe, Sn, P, As or Sb were considered. The formation energy per atom of each\ncompound was calculated. By comparing our calculated formation energies to\nthose calculated for phases in the Inorganic Crystal Structure Database (ICSD)\nof observed phases, we estimate that inverse-Heuslers with formation energies\nwithin 0.052 eV/atom of the calculated convex hull are reasonably likely to be\nsynthesizable in equilibrium. The observed trends in the formation energy and\nrelative structural stability as the \\textit{X}, \\textit{Y} and \\textit{Z}\nelements vary are described. In addition to the Slater-Pauling gap after 12\nstates per formula unit in one of the spin channels, inverse-Heusler phases\noften have gaps after 9 states or 14 states. We describe the origin and\noccurrence of these gaps. We identify 14 inverse-Heusler semiconductors, 51\nhalf-metals and 50 near half-metals with negative formation energy. In\naddition, our calculations predict 4 half-metals and 6 near half-metals to lie\nclose to the respective convex hull of stable phases, and thus may be\nexperimentally realized under suitable synthesis conditions, resulting in\npotential candidates for future spintronics applications."
    },
    {
        "anchor": "Grown-in beryllium diffusion in indium gallium arsenide: An ab initio,\n  continuum theory and kinetic Monte Carlo study: A roadblock in utilizing InGaAs for scaled-down electronic devices is its\nanomalous dopant diffusion behavior; specifically, existing models are not able\nto explain available experimental data on beryllium diffusion consistently. In\nthis paper, we propose a comprehensive model, taking self-interstitial\nmigration and Be interaction with Ga and In into account. Density functional\ntheory (DFT) calculations are first used to calculate the energy parameters and\ncharge states of possible diffusion mechanisms. Based on the DFT results,\ncontinuum modeling and kinetic Monte Carlo simulations are then performed. The\nmodel is able to reproduce experimental Be concentration profiles. Our results\nsuggest that the Frank-Turnbull mechanism is not likely, instead, kick-out\nreactions are the dominant mechanism. Due to a large reaction energy\ndifference, the Ga interstitial and the In interstitial play different roles in\nthe kick-out reactions, contrary to what is usually assumed. The DFT\ncalculations also suggest that the influence of As on Be diffusion may not be\nnegligible.",
        "positive": "Predominance of non-adiabatic effects in zero-point renormalization of\n  the electronic band gap: Electronic and optical properties of materials are affected by atomic motion\nthrough the electron-phonon interaction: not only band gaps change with\ntemperature, but even at absolute zero temperature, zero-point motion causes\nband-gap renormalization. We present a large-scale first-principles evaluation\nof the zero-point renormalization of band edges beyond the adiabatic\napproximation. For materials with light elements, the band gap renormalization\nis often larger than 0.3 eV, and up to 0.7 eV. This effect cannot be ignored if\naccurate band gaps are sought. For infrared-active materials, global agreement\nwith available experimental data is obtained only when non-adiabatic effects\nare taken into account. They even dominate zero-point renormalization for many\nmaterials, as shown by a generalized Fr\\\"ohlich model that includes multiple\nphonon branches, anisotropic and degenerate electronic extrema, whose range of\nvalidity is established by comparison with first-principles results."
    },
    {
        "anchor": "Upscaling High-Quality CVD Graphene Devices to 100 Micron-Scale and\n  Beyond: We describe a method for transferring ultra large-scale CVD-grown graphene\nsheets. These samples can be fabricated as large as several cm$^2$ and are\ncharacterized by magneto-transport measurements on SiO$_2$ substrates. The\nprocess we have developed is highly effective and limits damage to the graphene\nall the way through metal liftoff, as shown in carrier mobility measurements\nand the observation of the quantum Hall effect. The charge-neutral point is\nshown to move drastically to near-zero gate voltage after a 2-step\npost-fabrication annealing process, which also allows for greatly diminished\nhysteresis.",
        "positive": "Effects of self-consistency and plasmon-pole models on GW calculations\n  for closed-shell molecules: We present theoretical calculations of quasiparticle energies in closed-shell\nmolecules using the GW method. We compare three different approaches: a\nfull-frequency $G_0W_0$ (FF-$G_0W_0$) method with density functional theory\n(DFT-PBE) used as a starting mean field; a full-frequency $GW_0$ (FF-$GW_0$)\nmethod where the interacting Green's function is approximated by replacing the\nDFT energies with self-consistent quasiparticle energies or Hartree-Fock\nenergies; and a $G_0W_0$ method with a Hybertsen-Louie generalized plasmon-pole\nmodel (HL GPP-$G_0W_0$). While the latter two methods lead to good agreement\nwith experimental ionization potentials and electron affinities for methane,\nozone, and beryllium oxide molecules, FF-$G_0W_0$ results can differ by more\nthan one electron volt from experiment. We trace this failure of the\nFF-$G_0W_0$ method to the occurrence of incorrect self-energy poles describing\nshake-up processes in the vicinity of the quasiparticle energies."
    },
    {
        "anchor": "Doping optimization for the power factor of bipolar thermoelectric\n  materials: Bipolar carrier transport is often a limiting factor in the thermoelectric\nefficiency of narrow bandgap materials at high temperatures due to the\nreduction in the Seebeck coefficient and the introduction of an additional term\nto the thermal conductivity. Using the Boltzmann transport formalism and a\ntwo-band model, we simulate transport through bipolar systems and calculate\ntheir thermoelectric transport properties: the electrical conductivity, the\nSeebeck coefficient and the thermoelectric power factor. We present an\ninvestigation into the doping optimisation of such materials, showing the\ndetrimental impact that rising temperatures have if the doping (and the Fermi\nlevel) is not optimised for each operating temperature. We also show that the\ndoping levels for optimized power factors at a given operating temperature\ndiffer in bipolar systems compared to unipolar ones. We show finally that at\n600 K, in a bipolar material with bandgap approximately that of Bi2Te3, the\noptimal doping required can reside between 10% - 30% larger than that required\nfor an optimal unipolar material depending on the electronic scattering details\nof the material.",
        "positive": "Anomalous dependence of thermoelectric parameters on carrier\n  concentration and electronic structure in Mn-substituted Fe2CrAl Heusler\n  alloy: We investigate the high temperature thermoelectric properties of Heusler\nalloys Fe2-xMnxCrAl (0<x<1). Substitution of 12.5% Mn at Fe-site (x = 0.25)\ncauses a significant increase in high temperature resistivity (\\r{ho}) and an\nenhancement in the Seebeck coefficient (S), as compared to the parent alloy.\nHowever, as the concentration of Mn is increased above 0.25, a systematic\ndecrement in the magnitude of both parameters is noted. These observations have\nbeen ascribed (from theoretical analysis) to a change in band gap and\nelectronic structure of Fe2CrAl with Mn-substitution. Due to absence of mass\nfluctuations and lattice strain, no significant change in thermal conductivity\nis seen across this series of Heusler alloys. Additionally, S drastically\nchanges its magnitude along with a crossover from negative to positive above\n900 K, which has been ascribed to the dominance of holes over electrons in high\ntemperature regime. In this series of alloys, S and \\r{ho} shows a strong\ndependence on the carrier concentration and strength of d-d hybridization\nbetween Fe/Mn and Cr atoms."
    },
    {
        "anchor": "Extremely large magnetoresistance in few-layer graphene/boron-nitride\n  heterostructures: Understanding magnetoresistance, the change in electrical resistance upon an\nexternal magnetic field, at the atomic level is of great interest both\nfundamentally and technologically. Graphene and other two-dimensional layered\nmaterials provide an unprecedented opportunity to explore magnetoresistance at\nits nascent stage of structural formation. Here, we report an extremely large\nlocal magnetoresistance of ~ 2,000% at 400 K and a non-local magnetoresistance\nof > 90,000% in 9 T at 300 K in few-layer graphene/boron-nitride\nheterostructures. The local magnetoresistance is understood to arise from large\ndifferential transport parameters, such as the carrier mobility, across various\nlayers of few-layer graphene upon a normal magnetic field, whereas the\nnon-local magnetoresistance is due to the magnetic field induced\nEttingshausen-Nernst effect. Non-local magnetoresistance suggests the\npossibility of a graphene based gate tunable thermal switch. In addition, our\nresults demonstrate that graphene heterostructures may be promising for\nmagnetic field sensing applications.",
        "positive": "Isolated flat bands in an interlocking-circles lattice: Flat-band physics has attracted much attention in recently years because of\nits interesting properties and important applications. Some typical lattices\nhave been proposed to generate flat bands, such as Kagome and Lieb lattices.\nThe flat bands in these lattices contact with other bands rather than isolated.\nHowever, an ideal flat band should be isolated, because isolation is a\nprerequisite for a number of important applications. Here, we propose a new\nlattice that can produce isolated flat bands. The lattice is named as\ninterlocking-circles lattice because its pattern seems like interlocking\ncircles. Moreover, the new lattice is realized in graphene by hydrogenation. In\nthe hydrogenated graphene, there are two nontrivial isolated flat bands\nappearing around the Fermi level. Upon hole or electron doping, the flat bands\nsplit into spin-polarized bands and then result in a ferromagnetic graphene.\nOur work not only proposes a new type of lattice but also opens a way to find\nsystems with isolated flat bands."
    },
    {
        "anchor": "Adhesive wear mechanisms in the presence of weak interfaces: Insights\n  from an amorphous model system: Engineering wear models are generally empirical and lack connections to the\nphysical processes of debris generation at the nanoscale to microscale. Here,\nwe thus analyze wear particle formation for sliding interfaces in dry contact\nwith full and reduced adhesion. Depending on the material and interface\nproperties and the local slopes of the surfaces, we find that colliding surface\nasperities can either deform plastically, form wear particles, or slip along\nthe contact junction surface without significant damage. We propose a mechanism\nmap as a function of material properties and local geometry, and confirm it\nusing quasi-two-dimensional and three-dimensional molecular dynamics and\nfinite-element simulations on an amorphous, siliconlike model material. The\nframework developed in the present paper conceptually ties the regimes of weak\nand strong interfacial adhesion together and can explain that even unlubricated\nsliding contacts do not necessarily lead to catastrophic wear rates. A salient\nresult of the present paper is an analytical expression of a critical length\nscale, which incorporates interface properties and roughness parameters.\nTherefore, our findings provide a theoretical framework and a quantitative map\nto predict deformation mechanisms at individual contacts. In particular,\ncontact junctions of sizes above the critical length scale contribute to the\ndebris formation.",
        "positive": "Bowl breakout, escaping the positive region when searching for saddle\n  points: We present a scheme improving the minimum-mode following method for finding\nfirst order saddle points by confining the displacements of atoms to the subset\nof those subject to the largest force. By doing so it is ensured that the\ndisplacement remains of a local character within regions where all eigenvalues\nof the Hessian matrix are positive. However, as soon as a region is entered\nwhere an eigenvalue turns negative all atoms are released to maintain the\nability of determining concerted moves. Applying the proposed scheme reduces\nthe required number of force calls for the determination of connected saddle\npoints by a factor two or more compared to a free search. Furthermore, a wider\ndistribution of the relevant low barrier saddle points is obtained. Finally,\nthe dependency on the initial distortion and the applied maximal step size is\nreduced making minimum-mode guided searches both more robust and applicable."
    },
    {
        "anchor": "Intrinsic ferromagnetic axion states and a single pair of Weyl fermions\n  in the stable-state Mn\\emph{X}$_{2}$\\emph{B}$_{2}$\\emph{T}$_{6}$-family\n  materials: The intrinsic ferromagnetic (FM) axion insulators and Weyl semimetals (WSMs)\nwith only single pair of Weyl points have drawn intensive attention but so far\nremain rare and elusive in real materials. Here, we propose a new class of\nMn\\emph{X}$_{2}$\\emph{B}$_{2}$\\emph{T}$_{6}$-B (\\emph{X}=Ge, Sn, or Pb;\n\\emph{B}=Sb or Bi; \\emph{T}=Se or Te) family that is the stable structural form\nof this system. We find that the Mn\\emph{X}$_{2}$\\emph{B}$_{2}$\\emph{T}$_{6}$-B\nfamily has not only the intrinsic FM axion insulators\nMnGe$_{2}$Bi$_{2}$Te$_{6}$-B, MnSn$_{2}$Bi$_{2}$Te$_{6}$-B, and\nMnPb$_{2}$Bi$_{2}$Te$_{6}$-B, but also the intrinsic WSM\nMnSn$_{2}$Sb$_{2}$Te$_{6}$-B with only a single pair of Weyl points. Thus, the\nMn\\emph{X}$_{2}$\\emph{B}$_{2}$\\emph{T}$_{6}$-B family can provide an ideal\nplatform to explore the exotic topological magnetoelectric effect and the\nintrinsic properties related to Weyl points.",
        "positive": "Laser-based angle-resolved photoemission spectroscopy with micrometer\n  spatial resolution and detection of three-dimensional spin vector: We have developed a state-of-the-art apparatus for laser-based spin- and\nangle-resolved photoemission spectroscopy with micrometer spatial resolution\n(micro-SARPES). This equipment is achieved through the combination of a\nhigh-resolution photoelectron spectrometer, a 6-eV laser with high photon flux\nthat is focused down to a few micrometers, a high-precision sample stage\ncontrol system, and a double very-low-energy-electron-diffraction spin\ndetector. The setup achieves an energy resolution of 1.5 (5.5) meV without\n(with) the spin detection mode, compatible with a spatial resolution better\nthan 10 micrometers. This enables us to probe both spatially-resolved\nelectronic structures and vector information of spin polarization in three\ndimensions. The performance of micro-SARPES apparatus is demonstrated by\npresenting ARPES and SARPES results from topological insulators and Au\nphotolithography patterns on a Si (001) substrate."
    },
    {
        "anchor": "On-surface synthesis of nitrogen-doped nanographenes with 5-7 membered\n  rings: We report on the formation of nitrogen-doped nanographenes containing five-\nand seven-membered rings by thermally induced cyclodehydrogenation on the\nAu(111) surface. Using scanning tunneling microscopy and supported by\ncalculations, we investigated the structure of precursor and targets, as well\nas of intermediates. Scanning tunneling spectroscopy shows that the electronic\nproperties of the target nanographenes are strongly influenced by the\nadditional formation of non-hexagonal rings.",
        "positive": "Emergent magnetism with continuous control in the ultrahigh conductivity\n  layered oxide PdCoO2: The current challenge to realizing continuously tunable magnetism lies in our\ninability to systematically change properties such as valence, spin, and\norbital degrees of freedom as well as crystallographic geometry. Here, we\ndemonstrate that ferromagnetism can be externally turned on with the\napplication of low-energy helium implantation and subsequently erased and\nreturned to the pristine state via annealing. This high level of continuous\ncontrol is made possible by targeting magnetic metastability in the ultra-high\nconductivity, non-magnetic layered oxide PdCoO2 where local lattice distortions\ngenerated by helium implantation induce emergence of a net moment on the\nsurrounding transition metal octahedral sites. These highly-localized moments\ncommunicate through the itinerant metal states which triggers the onset of\npercolated long-range ferromagnetism. The ability to continuously tune\ncompeting interactions enables tailoring precise magnetic and magnetotransport\nresponses in an ultra-high conductivity film and will be critical to\napplications across spintronics."
    },
    {
        "anchor": "Possible centers of broadband near-IR luminescence in bismuth-doped\n  solids: $Bi^{+}$, Bi$_5^{3+}$, and Bi$_4^0$: Subvalent bismuth centers (interstitial $Bi^{+}$ ion, Bi$_5^{3+}$ cluster\nion, and Bi$_4^0$ cluster) are examined as possible centers of broadband\nnear-IR luminescence in bismuth-doped solids on the grounds of quantum-chemical\nmodeling and experimental data.",
        "positive": "Enhanced interlayer interactions in Ni-doped MoS$_2$, and structural and\n  electronic signatures of doping site: The crystal structure of MoS$_2$ with strong covalent bonds in plane and weak\nVan der Waals interactions out of plane gives rise to interesting properties\nfor applications such as solid lubrication, optoelectronics, and catalysis,\nwhich can be enhanced by transition-metal doping. However, the mechanisms for\nimprovement and even the structure of the doped material can be unclear, which\nwe address with theoretical calculations. Building on our previous work on\nNi-doping of the bulk 2H phase, now we compare to polytypes (1H monolayer and\n3R bulk), to determine favorable sites for Ni and the doping effect on\nstructure, electronic properties, and the layer dissociation energy. The most\nfavorable intercalation/adatom sites are tetrahedral intercalation for 3R (like\n2H) and Mo-atop for 1H. The relative energies indicate a possibility of phase\nchange from 2H to 3R with substitution of Mo or S. We find structural and\nelectronic properties that can be used to identify the doping sites, including\nmetallic behavior in Mo-substituted 3R and 2H, and in-gap states for Mo- and\nS-substituted 1H, which could have interesting optoelectronic applications. We\nobserve a large enhancement in the interlayer interactions of Ni-doped MoS$_2$,\nopposite to the effect of other transition metals. For lubrication\napplications, this increased layer dissociation energy could be the mechanism\nof low wear. Our systematic study shows the effect of doping concentration and\nwe extrapolate to the low-doping limit. This work gives insight into the\npreviously unclear structure of Ni-doped MoS$_2$ and how it can be detected\nexperimentally, the relation of energy and structures of doped monolayers and\nbulk systems, the electronic properties under doping, and the effect of doping\non interlayer interactions."
    },
    {
        "anchor": "Antiferromagnetic ordering in heavy fermion system Ce2Au2Cd: La2Au2Cd and Ce2Au2Cd were prepared from the elements by reactions in sealed\ntantalum tubes in a water-cooled sample chamber of an induction furnace. These\nintermetallics crystallize with the tetragonal Mo2FeB2 type, space group\nP4/mbm. While La2Au2Cd is Pauli paramagnetic, Ce2Au2Cd shows Curie-Weiss\nbehaviour above 100 K with an experimental magnetic moment of 2.41(2) muB/Ce\natom, indicating trivalent cerium. Antiferromagnetic ordering is detected for\nCe2Au2Cd at 5.01(2) K and magnetization measurements reveal a metamagnetic\ntransition at 3 K at a critical field of around 20 kOe with a saturation moment\nof 1.50(2)muB/Ce atom at 80 kOe. The low-temperature heat capacity properties\ncharacterize Ce2Au2Cd as a heavy fermion material with an electronic specific\nheat coefficient (gamma) = 807(5) mJ/mol K2 as compared to La2Au2Cd with gamma\n= 6(5) mJ/mol K2.",
        "positive": "Theory of the carbon vacancy in $4H$-SiC: crystal field and pseudo\n  Jahn-Teller effects: The carbon vacancy in $4H$-SiC is a powerful minority carrier recombination\ncenter and a major cause of degradation of SiC-based devices. Despite the\nextensiveness of the literature regarding the characterization and modeling of\nthe defect, many fundamental questions persist. Among them we have the shaky\nconnection of the EPR data to the electrical measurements, the physical origin\nof the pseudo-Jahn-Teller (pJT) effect, the reasoning for the observed\nsub-lattice dependence of the paramagnetic states, and the severe\ntemperature-dependence of some hyperfine signals which cannot be accounted for\nby a thermally-activated dynamic averaging between equivalent JT-distorted\nstructures. In this work we address these problems by means of semi-local and\nhybrid density functional calculations. We start by inventorying a total of\nfour vacancy structures. Diamagnetic states have well defined low-energy\nstructures, whereas paramagnetic states display metastability. This rich\nstructural variety is traced back to the filling of electronic states which are\nshaped by a crystal-field-dependent pJT effect. From calculated minimum energy\npaths for defect rotation and transformation mechanisms, combined with the\ncalculated formation energies and electrical levels, we arrived at a\nconfiguration-coordinate diagram of the defect. The diagram provides us with a\ndetailed first-principles picture of the defect when subject to optical and\nthermal excitations. The calculated acceptor and donor transitions agree well\nwith Z$_{1/2}$ and EH$_{6/7}$ trap energies, respectively. From comparison of\ncalculated and measured $U$-values, and correlating the site-dependent\nformation energies with the relative intensity of the DLTS peaks in as-grown\nmaterial, we assign Z$_{1}$ (EH$_{6}$) and Z$_{2}$ (EH$_{7}$) signals to\nacceptor (donor) transitions of carbon vacancies located on the $h$ and $k$\nsub-lattice sites, respectively."
    },
    {
        "anchor": "Temperature Effects in the thermal conductivity of aligned amorphous\n  Polyethylene -- A molecular Dynamics study: We analyze, through molecular dynamics simulations, the temperature\ndependence of the thermal conductivity (k) of chain-oriented amorphous\npolyethylene (PE). We find that at increasing levels of orientation, the\ntemperature corresponding to a peak k progressively decreases. Un-oriented PE\nexhibits the peak k at 350 K, while aligned PE under an applied strain of 400%\nshows a maximum at 100 K. This transition of peak k to lower temperatures with\nincreasing alignment is explained in terms of a crossover from disorder to\nanharmonicity dominated phonon transport in aligned polymers. Evidence for this\ncrossover is achieved by manipulating the disorder in the polymer structure and\nstudying the resulting change in temperature corresponding to peak k. Disorder\nis modified through a change in the dihedral parameters of the potential\nfunction, allowing a change in the relative fraction of trans and gauche\ntransformations. The results shed light on the underlying thermal transport\nprocesses in aligned polymers and hold importance for low temperature\napplications of polymer materials in thermal management technologies.",
        "positive": "Dynamic friction force in a carbon peapod oscillator: We investigate a new generation of fullerene nano-oscillators: a\nsingle-walled carbon nanotube with one buckyball inside with an operating\nfrequency in the tens-of-gigahertz range. A quantitative characterization of\nenergy dissipation channels in the peapod pair has been performed via molecular\ndynamics simulation. Edge effects are found to the dominant cause of dynamic\nfriction in the carbon-peapod oscillators. A comparative study on energy\ndissipation also reveals significant impact of temperature and impulse velocity\non the frictional force."
    },
    {
        "anchor": "Growth of large area graphene from sputtered films: Techniques for mass-production of large area graphene using an industrial\nscale thin film deposition tool could be the key to the practical realization\nof a wide range of technological applications of this material. Here, we\ndemonstrate the growth of large area polycrystalline graphene from sputtered\nfilms (a carbon-containing layer and a metallic layer) using in-situ or ex-situ\nrapid thermal processing in the temperature range from 650 to 1000 oC. It was\nfound that graphene always grows on the top surface of the stack, in close\ncontact with the Ni or Ni-silicide. Raman spectra typical of high quality\nexfoliated monolayer graphene were obtained for samples under optimised\nconditions. A fast cooling rate was found to be essential to the formation of\nmonolayer graphene. Samples with Ni atop SiC produced the best monolayer\ngraphene spectra with ~40% surface area coverage, whereas samples with Ni below\nSiC produced poorer quality graphene but 99% coverage. The flexibility of the\nsputtering process allows further optimization of the growth, with possibility\nof transferring the graphene to any insulator substrate in vacuum. We present a\npotential route for the production of graphene-on-insulator wafers, which would\nfacilitate easy integration of graphene into modern semiconductor device\nprocess flows.",
        "positive": "Investigation of variable temperature M\u00f6ssbauer spectrum of\n  YFe$_{0.5}$Cr$_{0.5}$O$_3$ perovskite: In this paper, we reported the preparation of YFe$_{0.5}$Cr$_{0.5}$O$_3$ by\nthe sol-gel method and studied its structure and M\\\"ossbauer spectrum at\nvariable temperatures. X-ray diffraction(XRD) analysis exhibits that the sample\nhas the orthorhombic structure with the Pnma space group, and the energy\ndispersive spectroscopy (EDS) analysis shows that the sample has Fe/Cr = 1:1,\nindicating that the sample is Fe half-doped YCrO$_3$. The hyperfine parameters\nof the M\\\"ossbauer spectrum at room temperature confirm that the\ncharacteristics of 57Fe in the sample were trivalent hexacoordinated\nhigh-spin(s=5/2), and the coexistence of doublet and the sextets at 250K\nindicate that the sample has superparamagnetic relaxation. The M\\\"ossbauer\nspectrum records the magnetic phase transition in the temperature range of\n250K-300K."
    },
    {
        "anchor": "Electronic Defects in Metal Oxide Photocatalysts: A deep understanding of defects is essential for the optimisation of\nmaterials for solar energy conversion. This is particularly true for metal\noxide photo(electro)catalysts, which typically feature high concentrations of\ncharged point defects that are electronically active. In photovoltaic\nmaterials, except for selected dopants, defects are considered detrimental and\nshould be eliminated to minimise charge recombination. However, photocatalysis\nis a more complex process where defects can play an active role, for example,\nby stabilising charge separation and mediating rate-limiting catalytic steps.\nHere, we review the behaviour of electronic defects in metal oxides, paying\nspecial attention to the principles underpinning the formation and function of\ntrapped charges in the form of polarons. We focus on how defects alter the\nelectronic structure, statically or transiently upon illumination, and discuss\nthe implications of such changes in light-driven catalytic reactions. Finally,\nwe consider the applicability of lessons learned from oxide defect chemistry to\nnew photocatalysts based on carbon nitrides, polymers and metal halide\nperovskites.",
        "positive": "Electron Transport in Diborides: Observation of Superconductivity in\n  ZrB2: We report on syntheses and electron transport properties of polycrystalline\nsamples of diborides (AB2) with different transition metals atoms (A=Zr,Nb,Ta).\nThe temperature dependence of resistivity, \\rho(T), and ac susceptibility of\nthese samples reveal superconducting transition of ZrB2 with Tc=5.5 K, while\nNbB2 and TaB2 have been observed nonsuperconducting up to 0.37 K. Hc2(T) is\nlinear in temperature below Tc, leading to a rather low Hc2(0)= 0.1 T. At T\nclose to Tc, Hc2(T) demonstrates a downward curvature. We conclude that these\ndiborides as well as MgB2 samples behaves like a simple metals in the normal\nstate with usual Bloch-Gr\\\"uneisen temperature dependence of resistivity and\nwith Debye temperatures: 280 K, 460 K and 440 K, for ZrB2, NbB2 and MgB2,\nrespectively, rather than T^2 and T^3 as previously reported for MgB2."
    },
    {
        "anchor": "Origin of high thermal conductivity in disentangled ultra-high molecular\n  weight polyethylene films: ballistic phonons within enlarged crystals: The thermal transport properties of oriented polymers are of fundamental and\npractical interest. High thermal conductivities ($\\gtrsim 50$\nWm$^{-1}$K$^{-1}$) have recently been reported in disentangled ultra-high\nmolecular weight polyethylene (UHMWPE) films, considerably exceeding prior\nreported values for oriented films. However, conflicting explanations have been\nproposed for the microscopic origin of the high thermal conductivity. Here, we\nreport a characterization of the thermal conductivity and mean free path\naccumulation function of disentangled UHMWPE films (draw ratio $\\sim 200$)\nusing cryogenic steady-state thermal conductivity measurements and transient\ngrating spectroscopy. We observe a marked dependence of the thermal\nconductivity on grating period over temperatures from 30 - 300 K. Considering\nthis observation, cryogenic bulk thermal conductivity measurements, and\nanalysis using an anisotropic Debye model, we conclude that longitudinal atomic\nvibrations with mean free paths around 400 nanometers are the primary heat\ncarriers and that the high thermal conductivity for draw ratio $\\gtrsim 150$\narises from the enlargement of extended crystals with drawing. The mean free\npaths appear to remain limited by the extended crystal dimensions, suggesting\nthat the upper limit of thermal conductivity of disentangled UHMWPE films has\nnot yet been realized.",
        "positive": "Fingerprints of the Strong Interaction between Monolayer MoS2 and Gold: Gold-mediated exfoliation of MoS2 has attracted considerable interest in the\nrecent years. A strong interaction between MoS2 and Au facilitates preferential\nproduction of centimeter-sized monolayer MoS2 with near-unity yield and\nprovides a heterostructure system noteworthy from a fundamental standpoint.\nHowever, little is known about the detailed nature of the MoS2-Au interaction\nand its evolution with the MoS2 thickness. Here, we identify specific\nvibrational and binding energy fingerprints of such strong interaction using\nRaman and X-ray photoelectron spectroscopy, which indicate substantial strain\nand charge-transfer in monolayer MoS2. Near-field tip-enhanced Raman\nspectroscopy reveals heterogeneity of the MoS2-Au interaction at the nanoscale,\nreflecting the spatial non-conformity between the two materials. Far-field\nmicro-Raman spectroscopy shows that this interaction is strongly affected by\nthe roughness and cleanliness of the underlying Au. Our results elucidate the\nnature of the strong MoS2-Au interaction and provide guidance for strain and\ncharge doping engineering of MoS2."
    },
    {
        "anchor": "Characterization of oxygen defects in diamond by means of density\n  functional theory calculations: Point defects in diamond are of high interest as candidates for realizing\nsolid state quantum bits, bioimaging agents, or ultrasensitive electric or\nmagnetic field sensors. Various artificial diamond synthesis methods should\nintroduce oxygen contamination in diamond, however, the incorporation of oxygen\ninto diamond crystal and the nature of oxygen-related point defects are largely\nunknown. Oxygen may be potentially interesting as a source of quantum bits or\nit may interact with other point defects which are well established solid state\nqubits. Here we employ plane-wave supercell calculations within density\nfunctional theory, in order to characterize the electronic and magneto-optical\nproperties of various oxygen-related defects. Beside the trivial single\ninterstitial and substitutional oxygen defects we also consider their complexes\nwith vacancies and hydrogen atoms. We find that oxygen defects are mostly\nelectrically active and introduce highly correlated orbitals that pose a\nchallenge for density functional theory modeling. Nevertheless, we are able to\nidentify the fingerprints of substitutional oxygen defect, the oxygen-vacancy\nand oxygen-vacancy-hydrogen complexes in the electron paramagnetic resonance\nspectrum. We demonstrate that first principles calculations can predict the\nmotional averaging of the electron paramagnetic resonance spectrum of defects\nthat are subject to Jahn-Teller distortion. We show that the high-spin neutral\noxygen-vacancy defect exhibits very fast non-radiative decay from its optical\nexcited state that might hinder to apply it as a qubit.",
        "positive": "First-principles calculation of H vibrational excitations at a\n  dislocation core of Pd: Palladium is an ideal system for understanding the behavior of hydrogen in\nmetals. In Pd, H is located both in octahedral sites and in dislocation cores,\nwhich act as nanoscale H traps and form Cottrell atmospheres. Adjacent to a\ndislocation core, H experiences the largest possible distortion in alpha-Pd. Ab\ninitio density-functional theory computes the potential energy for a hydrogen\nin an octahedral site in alpha-Pd and in a trap site at the core of a partial\nof an edge dislocation. The Pd partial dislocation core changes the environment\nfor H, distorting the H-Pd bonding which changes the local potential,\nvibrational spectra, and inelastic form factor for an isolated H atom. The\ndecrease in excitation energy is consistent with experiments, and the\ncalculations predict distortions to the H wavefunction."
    },
    {
        "anchor": "Acoustic and Optical Phonons in Quasi-Two-Dimensional MPX3 Van der Waals\n  Semiconductors: We report the results of the investigation of the acoustic and optical\nphonons in quasi-two-dimensional antiferromagnetic semiconductors of the\ntransition metal phosphorus trisulfide family with Mn, Fe, Co, Ni, and Cd as\nmetal atoms. The Brillouin-Mandelstam and Raman light scattering spectroscopies\nwere conducted at room temperature to measure the acoustic and optical phonon\nfrequencies close to the Brillouin zone center. The absorption and index of\nrefraction were measured in the visible and infrared ranges using the\nreflectometry technique. We found an intriguing large variation, over ~28%, in\nthe acoustic phonon group velocities in this group of materials with similar\ncrystal structures. Our data indicate that the full-width-at-half-maximum of\nthe acoustic phonon peaks is strongly affected by the optical properties and\nthe electronic band gap. The acoustic phonon lifetime extracted for some of the\nmaterials was correlated with their thermal properties. The obtained results\nare important for understanding the layered van der Waals semiconductors and\nfor assessing their potential for optoelectronic and spintronic device\napplications.",
        "positive": "Ultrasonic Production of Nano-Size Dispersions and Emulsions: Ultrasound is a well-established method for particle size reduction in\ndispersions and emulsions. Ultrasonic processors are used in the generation of\nnano-size material slurries, dispersions and emulsions because of the potential\nin the deagglomeration and the reduction of primaries. These are the mechanical\neffects of ultrasonic cavitation. Ultrasound can also be used to influence\nchemical reactions by the cavitation energy. This is sonochemistry. As the\nmarket for nano-size materials grows, the demand for ultrasonic processes at\nproduction level increases. At this stage, energy efficiency becomes important.\nSince the energy required per weight or volume of processed material links\ndirectly to the equipment size required, optimization of the process efficiency\nis essential to reduce investment and operational costs. Furthermore it is\nrequired to scale the lab and bench top configurations to this final level\nwithout any variations in the process achievements. Scale up by power alone\nwill not do this."
    },
    {
        "anchor": "Thickness dependence of magnetic properties of (Ga,Mn)As: We report on a monotonic reduction of Curie temperature in dilute\nferromagnetic semiconductor (Ga,Mn)As upon a well controlled\nchemical-etching/oxidizing thinning from 15 nm down to complete removal of the\nferro- magnetic response. The effect already starts at the very beginning of\nthe thinning process and is accompanied by the spin reorientation transition of\nthe in-plane uniaxial anisotropy. We postulate that a negative gradient along\nthe growth direction of self-compensating defects (Mn interstitial) and the\npresence of surface donor traps gives quantitative account on these effects\nwithin the p-d mean field Zener model with adequate mod- ifications to take a\nnonuniform distribution of holes and Mn cations into account. The described\nhere effects are of practical importance for employing thin and ultrathin\nlayers of (Ga,Mn)As or relative compounds in concept spintronics devices, like\nresonant tunneling devices in particular.",
        "positive": "Orientation-dependent ferroelectricity of strained PbTiO$_3$ films: PbTiO$_3$ is a simple but very important ferroelectric oxide that has been\nextensively studied and widely used in various technological applications.\nHowever, most previous studies and applications were based on the bulk material\nor the conventional [$001$]-orientated films. There are few studies on\nPbTiO$_3$ films grown along other crystalline axes. In this study, a\nfirst-principles calculation was performed to compute the polarization of\nPbTiO$_3$ films strained by SrTiO$_3$ and LaAlO$_3$ substrates. Our results\nshow that the polarization of PbTiO$_3$ films strongly depends on the growth\norientation as well as the monoclinic angles. Further, it is suggested that the\nferroelectricity of PbTiO$_3$ mainly depends on the tetragonality of the\nlattice, instead of the simple strain."
    },
    {
        "anchor": "Evidence of electronic phase arrest and glassy ferromagnetic behaviour\n  in (Nd0.4Gd0.3)Sr0.3MnO3 manganite : Comparative study between bulk and\n  nanometric samples: The effect of doping of rare earth Gd 3+ ion replacing Nd 3+ in\nNd0.7Sr0.3MnO3 is investigated in details. Measurements of resistivity,\nmagnetoresistance, magnetization, linear and non linear ac magnetic\nsusceptibility on chemically synthesized (Nd0.7-xGdx)Sr0.3MnO3 shows various\ninteresting features with doping level x=0.3. Comparative study has been\ncarried out between a bulk and a nanometric sample (grain size ~ 60 nm)\nsynthesized from the same as prepared powder to maintain identical\nstoichiometry. Resistivity of the samples shows strong dependence on the\nmagnetic field - temperature history. The magnetoresistance of the samples also\nshow strong irreversibility with respect to sweeping of the field between\nhighest positive and negative values. Moreover, resistivity is found to\nincrease with time after field cooling and then switching off the field. All\nthese phenomena have been attributed to phase separation effect and arrest of\nphases in the samples. Furthermore, the bulk sample displays a spin glass like\nbehaviour as evident from frequency dependence of linear ac magnetic\nsusceptibility and critical divergence of the nonlinear ac magnetic\nsusceptibility. The experimentally obtained characteristic time t after\ndynamical scaling analysis of the frequency dependence of the ac susceptibility\nis found to be t=10-17 s which implies that the system is different from a\ncanonical spin glass. An unusual frequency dependence of the second harmonic of\nac susceptibility around the magnetic transition temperature led us to\ndesignate the magnetic state of the sample to be glassy ferromagnetic. On\nreduction of grain size low field magnetoresistance and phase arrest phenomena\nare found to enhance but the glassy state is observed to be destabilized in the\nnanometric sample.",
        "positive": "A computational high-throughput search for new ternary superalloys: In 2006, a novel cobalt-based superalloy was discovered [1] with mechanical\nproperties better than some conventional nickel-based superalloys. As with\nconventional superalloys, its high performance arises from the\nprecipitate-hardening effect of a coherent L1$_2$ phase, which is in two-phase\nequilibrium with the fcc matrix. Inspired by this unexpected discovery of an\nL1$_2$ ternary phase, we performed a first-principles search through 2224\nternary metallic systems for analogous precipitate-hardening phases of the form\n$X_{3}$[$A_{0.5}, B_{0.5}$], where $X$ = Ni, Co, or Fe, and [$A,B$] = Li, Be,\nMg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn Ga, Sr, Y, Zr, Nb, Mo,\nTc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, or Tl.\nWe found 102 systems that have a smaller decomposition energy and a lower\nformation enthalpy than the Co$_{3}$(Al, W) superalloy. They have a stable\ntwo-phase equilibrium with the host matrix within the concentration range\n$0<x<1$ ($X_{3}$[$A_{x}, B_{1-x}$]) and have a relative lattice mismatch with\nthe host matrix of less than or equal to 5%. These new candidates, narrowed\nfrom 2224 systems, suggest possible experimental exploration for identifying\nnew superalloys. Of these 102 systems, 37 are new; they have no reported phase\ndiagrams in standard databases. Based on cost, experimental difficulty, and\ntoxicity, we limit these 37 to a shorter list of six promising candidates of\nimmediate interest. Our calculations are consistent with current experimental\nliterature where data exists."
    },
    {
        "anchor": "Influence of elastic strain on the thermodynamics and kinetics of\n  lithium vacancy in bulk LiCoO2: The influence of elastic strain on the lithium vacancy formation and\nmigration in bulk LiCoO2 is evaluated by means of first-principles calculations\nwithin density functional theory (DFT). Strain dependent energies are\ndetermined directly from defective cells and also within linear elasticity\ntheory from the elastic dipole tensor (Gij) for ground state and saddle point\nconfigurations. We analyze finite size-effects in the calculation of Gij,\ncompare the predictions of the linear elastic model with those obtained from\ndirect calculations of defective cells under strain and discuss the\ndifferences. Based on our data, we calculate the variations in vacancy\nconcentration and mobility due to the presence of external strain in bulk\nLiCoO2 cathodes. Our results reveal that elastic in-plane and out-of-plane\nstrains can significantly change the ionic conductivity of bulk LiCoO2 by an\norder of magnitude and thus strongly affect the performance of Li-secondary\nbatteries.",
        "positive": "Ordering in ternary nitride semiconducting alloys: We present a thorough theoretical study of ordering phenomena in nitride\nternary alloys GaInN, AlInN, and AlGaN. Using the Monte Carlo approach and\nenergetics based on the Keating model we analyze the influence of various\nfactors on ordering in bulk crystals and epitaxial layers. We characterize the\ndegree of both short range order (SRO) and long ranger order (LRO) for\ndifferent compositions, temperatures and for substrates associated with\ndifferent epitaxial strain. For the description of the SRO the Warren-Cowley\nparameters related to the first four coordination shells are used. The LRO is\ndetected by means of the introduced sim-LRO parameter, based on the\nBragg-Williams approach. The description of the observed long-range ordering\npatterns and conditions for their occurrence follows."
    },
    {
        "anchor": "Tunable Optoelectronic Properties of Triply-Bonded Carbon Molecules with\n  Linear and Graphyne Substructures: In this paper we present a detailed computational study of the electronic\nstructure and optical properties of triply-bonded hydrocarbons with linear, and\ngraphyne substructures, with the aim of identifying their potential in\nopto-electronic device applications. For the purpose, we employed a correlated\nelectron methodology based upon the Pariser-Parr-Pople model Hamiltonian,\ncoupled with the configuration interaction (CI) approach, and studied\nstructures containing up to 42 carbon atoms. Our calculations, based upon\nlarge-scale CI expansions, reveal that the linear structures have intense\noptical absorption at the HOMO-LUMO gap, while the graphyne ones have those at\nhigher energies. Thus, the opto-electronic properties depend on the topology of\nthe {graphyne substructures, suggesting that they can be tuned by means of\nstructural modifications. Our results are in very good agreement with the\navailable experimental data.",
        "positive": "Large gap quantum spin Hall insulator, massless Dirac fermions and\n  bilayer graphene analogue in InAs/Ga(In)Sb heterostructures: The quantum spin Hall insulator (QSHI) state has been demonstrated in two\nsemiconductor systems - HgTe/CdTe quantum wells (QWs) and InAs/GaSb QW\nbilayers. Unlike the HgTe/CdTe QWs, the inverted band gap in InAs/GaSb QW\nbilayers does not open at the $\\Gamma$ point of the Brillouin zone, preventing\nthe realization of massless Dirac fermions. Here, we propose a new class of\nsemiconductor systems based on InAs/Ga(In)Sb multilayers, hosting a QSHI state,\na graphene-like phase and a bilayer graphene analogue, depending on their layer\nthicknesses and geometry. The QSHI gap in the novel structures can reach up to\n60 meV for realistic design and parameters. This value is twice as high as the\nthermal energy at room temperature and significantly extends the application\npotential of III-V semiconductor-based topological devices."
    },
    {
        "anchor": "Multifunctional Two-dimensional van der Waals Janus Magnet Cr-based\n  Dichalcogenide Halides: Two-dimensional van der Waals Janus materials and their heterostructures\noffer fertile platforms for designing fascinating functionalities. Here, by\nmeans of systematic first-principles studies on van der Waals Janus monolayer\nCr-based dichalcogenide halides CrYX (Y=S, Se, Te; X=Cl, Br, I), we find that\nCrSX (X=Cl, Br, I) are the very desirable high TC ferromagnetic semiconductors\nwith an out-of-plane magnetization. Excitingly, by the benefit of the large\nmagnetic moments on ligand S2- anions, the sought-after large-gap quantum\nanomalous Hall effect and sizable valley splitting can be achieved through the\nmagnetic proximity effect in van der Waals heterostructures CrSBr/Bi2Se3/CrSBr\nand MoTe2/CrSBr, respectively. Additionally, we show that large\nDzyaloshinskii-Moriya interactions give rise to skyrmion states in CrTeX (X=Cl,\nBr, I) under external magnetic fields. Our work reveals that two-dimensional\nJanus magnet Cr-based dichalcogenide halides have appealing\nmultifunctionalities in the applications of topological electronic and\nvalleytronic devices.",
        "positive": "Anodic aqueous electrophoretic deposition of titanium dioxide using\n  carboxylic acids as dispersing agents: The dispersion of anatase phase TiO2 powder in aqueous suspensions was\ninvestigated by zeta-potential and agglomerate size analysis. The iso-electric\npoint (IEP) of anatase was determined to be at pH 2.8 using monoprotic acids\nfor pH adjustment. In comparison, it was found that the use of carboxylic\nacids, citric and oxalic, caused a decrease in zeta-potential through the\nadsorption of negatively charged groups to the particle surfaces. The use of\nthese reagents was shown to enable effective anodic electrophoretic deposition\n(EPD) of TiO2 onto graphite substrates at low pH levels with a decreased level\nof bubble damage in comparison with anodic EPD from basic suspensions. The\nresults obtained demonstrate that the IEP of TiO2 varies with the type of\nreagent used for pH adjustment. The low pH level of the IEP and the ability to\ndecrease the zeta-potential through the use of carboxylic acids suggest that\nthe anodic EPD of anatase is more readily facilitated than cathodic EPD."
    },
    {
        "anchor": "Harnessing the magnetic proximity effect: induced spin polarization in\n  Ni/Si interfaces: The investigation of the properties of metal-semiconductor interfaces has\ngained significant attention due to the unique features that emerge from the\ncombination of both metal and semiconductor attributes. In this report, the\nmagnetic properties of Ni/Si interfaces utilizing X-ray magnetic circular\ndichroism (XMCD) spectroscopy at the Ni and Si edges have been studied. This\napproach allows to distinguish unambiguously the local magnetism on Ni and Si\nvia individual core-level excitations. Two samples with different semiconductor\ndopings were investigated using both total electron yield (TEY) and\nreflectivity configurations. The experimental results uncovered magnetization\nat equilibrium in both the metallic layer and in the proximal layer of the\nsemiconductor substrate, implying the presence of induced spin polarization in\nSi at equilibrium, possibly arising from the depletion layer region. These\nresults hold significant value in the field of spintronics, as similar systems\nhave been demonstrated to generate spin injection through optical medium,\nopening a new pathway for next generation nonvolatile high speed devices.",
        "positive": "Consistent multiphase-field theory for interface driven multidomain\n  dynamics: We present a new multiphase-field theory for describing pattern formation in\nmulti-domain and/or multi-component systems. The construction of the free\nenergy functional and the dynamic equations is based on criteria that ensure\nmathematical and physical consistency. We first analyze previous\nmultiphase-field theories, and identify their advantageous and disadvantageous\nfeatures. On the basis of this analysis, we introduce a new way of constructing\nthe free energy surface, and derive a generalized multiphase description for\narbitrary number of phases (or domains). The presented approach retains the\nvariational formalism; reduces (or extends) naturally to lower (or higher)\nnumber of fields on the level of both the free energy functional and the\ndynamic equations; enables the use of arbitrary pairwise equilibrium\ninterfacial properties; penalizes multiple junctions increasingly with the\nnumber of phases; ensures non-negative entropy production, and the convergence\nof the dynamic solutions to the equilibrium solutions; and avoids the\nappearance of spurious phases on binary interfaces. The new approach is tested\nfor multi-component phase separation and grain coarsening."
    },
    {
        "anchor": "Structural, Morphological and Electrical Properties of Porous Silicon\n  Prepared Under Laser Illumination: Porous silicon (PSi) layers has been prepared in this work via\nphotoelectrochemical (PEC) etching process of an n type silicon wafers of two\nresistivities (3.5 \u007fohm.cm and 0.02 \u007fohm.cm) in hydrofluoric (HF) acid of 24.5\nprecent concentration at different etching times (5 to 25 min). The irradiation\nhas been achieved using laser beam of 2W power and 810 nm wavelength. We have\nstudied the morphological and structural properties of PSi layers using the\ntechniques of Xray Diffraction (XRD) and Scanning Electron Microscopy (SEM) and\nGravimetric method. The Xray Diffraction data shows that the structure aspect\nof PSi layers remains crystalline as well as the decreasing of diffraction\nangle (thetaB) of Xray from PSi layers (29 to 26 degree) and increasing of the\nlattice parameter values of PSi structures with increasing of etching times\nfrom 5 to 25 min., and the resistivity of silicon substrates from 0.02 to 3.5\nohm.cm. The nanocrystallite size is decreasing from (20.72 to 5.13 nm) with\nincreasing of etching times, and the resistivity of silicon substrates. The SEM\nimages shows that the values of pore width and PSi layer thickness increases\nfrom (0.5 to 6.25 micrometer) and (6.7 to 47 micrometer) respectively with\nincreasing of etching times and silicon substrates resistivities, while the\nvalues of the thickness of walls between pores has been varied from (1.25 to\n0.03 micrometer) with increasing of etching times and silicon substrates\nresistivities. The pore shape of pores has been varied from Cylindrical to\nRectangular and to Starful with varied of etching conditions. Further the\nmeasured specific surface area of PSi layers has been increased from (7.43 to\n235.35 m2/cm3) with increasing of etching times and silicon substrates\nresistivities.",
        "positive": "Ab-initio study of the effects induced by the electron-phonon scattering\n  in carbon based nanostructures: In this paper we investigate from first principles the effect of the\nelectron-phonon interaction in two paradigmatic nanostructures:\ntrans-polyacetylene and polyethylene. We found that the strong electron-phonon\ninteraction leads to the appearance of complex structures in the frequency\ndependent electronic self-energy. Those structures rule out any quasi-particle\npicture, and make the adiabatic and static approximations commonly used in the\nwell-established Heine Allen Cardona (HAC) approach inadequate. We propose,\ninstead, a fully ab-initio dynamical formulation of the problem within the Many\nBody Perturbation Theory framework. The present dynamical theory reveals that\nthe structures appearing in the electronic self-energy are connected to the\nexistence of packets of correlated electron/phonon states. These states appear\nin the spectral functions even at $T=0\\,K$, revealing the key role played by\nthe zero point motion effect. We give a physical interpretation of these states\nby disclosing their internal composition by mapping the Many Body problem to\nthe solution of an eigenvalue problem."
    },
    {
        "anchor": "FEAST fundamental framework for electronic structure calculations:\n  Reformulation and solution of the muffin-tin problem: In a recent article [1], the FEAST algorithm has been presented as a general\npurpose eigenvalue solver which is ideally suited for addressing the numerical\nchallenges in electronic structure calculations. Here, FEAST is presented\nbeyond the \"black-box\" solver as a fundamental modeling framework which can\nnaturally address the original numerical complexity of the electronic structure\nproblem as formulated by Slater in 1937 [2]. The non-linear eigenvalue problem\narising from the muffin-tin decomposition of the real-space domain is first\nderived and then reformulated to be solved exactly within the FEAST framework.\nThis new framework is presented as a fundamental and practical solution for\nperforming both accurate and scalable electronic structure calculations,\nbypassing the various issues of using traditional approaches such as\nlinearization and pseudopotential techniques. A finite element implementation\nof this FEAST framework along with simulation results for various molecular\nsystems are also presented and discussed.",
        "positive": "Infrared, terahertz, and microwave spectroscopy of the soft and central\n  modes in Pb(Mg1/3Nb2/3)O3: From the new infrared (IR) reflectivity and time-domain terahertz (THz)\nspectra combined with available high-frequency dielectric data above the MHz\nrange in a broad temperature range of 10-900 K, a full picture of the soft and\ncentral mode behavior in the classical relaxor ferroelectric Pb(Mg1/3Nb2/3)O3\n(PMN) is suggested. A detailed comparison is given with the recent hyper-Raman\nspectroscopy data (Phys. Rev. Lett. 117, 155501 (2016)), and also with other\navailable experiments based on inelastic light and neutron scattering. The\nclosest agreement is with the hyper-Raman data, both techniques yield the same\nnumber of soft-mode components and the same high-temperature softening towards\nthe temperature T* ~ 400 K. In addition to evaluation of the IR-THz data using\nfitting with standard factorized form of the dielectric function, we performed\na successful fitting of the same data using the effective medium approach\n(EMA), originally based on the assumption that the mesoscopic structure of PMN\nconsists of randomly oriented uniaxially anisotropic polar nanodomains (PNDs)\nwith somewhat harder TO polar modes in the direction along the local PND dipole\n(Phys. Rev. Lett. 96, 027601 (2006)). Evaluation using the Bruggeman EMA\nmodelling has been successfully applied in the entire investigated temperature\nrange. These results suggest that the response perpendicular to the local\ndipole moment, at high temperatures induced by random fields rather than PNDs,\nundergoes a classical softening from high temperatures with permittivity\nobeying the Curie-Weiss law, eps_per = C/(T-Tc), C = 1.7 x 10^5 K and Tc = 380\nK. Below the Burns temperature ~620 K, a GHz relaxation ascribed to flipping of\nthe PNDs emerges from the soft mode response, slows down and broadens,\nremaining quite strong towards the cryogenic temperatures, where it can be\nassigned to fluctuations of the PND boundaries."
    },
    {
        "anchor": "Origin of the low precipitation hardening in magnesium alloys: In this work electron backscattered diffraction (EBSD)-assisted slip trace\nanalysis and transmission electron microscopy have been utilized to investigate\nthe interaction of basal dislocations with precipitates in the Mg alloys\nMg-1%wt.Mn-0.7%wt.Nd (MN11) and Mg-9%wt.Al-1%wt.Zn (AZ91), with the ultimate\naim of determining the origin of their poor precipitation hardening.\nPrecipitates in these alloys have a plate-shaped morphology, with plates being,\nrespectively, perpendicular (MgxNdy) and parallel (Mg17Al12) to the basal plane\nof the magnesium matrix. Mechanical tests were carried out in solid solution\nand peak-aged samples, in tension and compression, both at RT and at moderate\ntemperature (250C). EBSD-assisted slip trace analysis revealed a clear\ndominance of basal slip under a wide range of testing conditions in the\npeak-aged MN11 and AZ91 alloys. At room temperature, the origin of the low\nprecipitation hardening observed lies at the easiness with which precipitates\nare sheared by basal dislocations, due to the lattice matching at the interface\nwith the Mg matrix. At high temperature, dislocation-precipitate interactions\nare highly dependent on the deformation mode. In tension, enhanced basal slip\nlocalization gives rise to high stress concentrations at the intersection\nbetween coarse slip traces and particle interfaces, leading to precipitate\nfracture; in compression, a more homogenous distribution of basal slip leads to\nthe dominance of particle shearing. Our study demonstrates experimentally that\nbasal dislocations are able to shear, and even fracture, the MgxNdy and\nMg17Al12 plates when, for appropriate testing conditions, the local stress due\nto dislocation accumulation at particle interfaces exceeds the precipitate\nstrength.",
        "positive": "Giant magneto-impedance in Ag-doped La0.7Sr0.3MnO3: The resistive and reactive parts of the magneto-impedance of sintered\nferromagnetic samples of La0.7Sr0.3-xAgxMnO3 (x = 0.05, 0.25) have been\nmeasured at room temperature (<Tc) over frequency interval 1KHz to 15MHz and in\npresence of magnetic field up to 4KOe. The field dependence of relative change\nin resistance is small in KHz region but increases strongly for higher\nfrequency of excitation. The maximum value of relative change in resistance at\nH =4KOe was found to be around 70% at 15MHz frequency.On the contrary the\ncorresponding change in reactance has less frequency sensitivity and the\nmaximum occurs at 1MHz frequency. The magneto-impedance is negative for all\nfrequencies. The 'normalized magneto-impedance' as defined by\n[Z(H)-Z(0)]/[Z(0)-Z(4K)] when plotted against scaled field H/H1/2 is found to\nbe frequency independent ; H1/2 is the field where 'normalized\nmagneto-impedance' is reduced to half its maximum. A phenomenological formula\nfor magneto-impedance Z (H) in ferromagnetic material is proposed based on Pade\napproximant. The formula for Z (H) predicts the scaled behavior of 'normalized\nmagneto-impedance'."
    },
    {
        "anchor": "Current-polarity dependent manipulation of antiferromagnetic domains: Antiferromagnets have a number of favourable properties as active elements in\nspintronic devices, including ultra-fast dynamics, zero stray fields and\ninsensitivity to external magnetic fields . Tetragonal CuMnAs is a testbed\nsystem in which the antiferromagnetic order parameter can be switched\nreversibly at ambient conditions using electrical currents . In previous\nexperiments, orthogonal in-plane current pulses were used to induce 90 degree\nrotations of antiferromagnetic domains and demonstrate the operation of\nall-electrical memory bits in a multi-terminal geometry . Here, we demonstrate\nthat antiferromagnetic domain walls can be manipulated to realize stable and\nreproducible domain changes using only two electrical contacts. This is\nachieved by using the polarity of the current to switch the sign of the\ncurrent-induced effective field acting on the antiferromagnetic sublattices.\nThe resulting reversible domain and domain wall reconfigurations are imaged\nusing x-ray magnetic linear dichroism microscopy, and can also be detected\nelectrically. The switching by domain wall motion can occur at much lower\ncurrent densities than those needed for coherent domain switching.",
        "positive": "Imaging Stacking Order in Few-Layer Graphene: Few-layer graphene (FLG) has been predicted to exist in various\ncrystallographic stacking sequences, which can strongly influence the\nelectronic properties of FLG. We demonstrate an accurate and efficient method\nto characterize stacking order in FLG using the distinctive features of the\nRaman 2D-mode. Raman imaging allows us to visualize directly the spatial\ndistribution of Bernal (ABA) and rhombohedral (ABC) stacking in tri- and\ntetra-layer graphene. We find that 15% of exfoliated graphene tri- and\ntetra-layers is comprised of micron-sized domains of rhombohedral stacking,\nrather than of usual Bernal stacking. These domains are stable and remain\nunchanged for temperatures exceeding $800^{\\circ}$C."
    },
    {
        "anchor": "Strain control of the competition between metallic and semiconducting\n  states in single-layers of TaSe$_3$: TaSe$_3$ is a metallic layered material whose structure is built from\nTaSe$_3$ trigonal prismatic chains. In this work we report a first-principles\ndensity functional theory study of TaSe$_3$ single-layers and we find that,\ndespite the existence of non negligible Se...Se interlayer interactions,\nTaSe$_3$ single layers are found to be metallic. However, an interesting\ncompetition between metallic and semiconducting states is found under the\neffect of strain. The single-layers keep the metallic behaviour under biaxial\nstrain although the nature of the hole carriers changes. In contrast, uniaxial\nstrain along the chains direction induces the stabilization of a semiconducting\nstate. Potential electronic instabilities due to Fermi surface nesting are\nfound for single-layers under either biaxial strain or uniaxial strain along\nthe long (inter-chain) axis of the layers. Bilayers and trilayers have also\nbeen considered. The structural and electronic features behind these unexpected\nobservations are analyzed.",
        "positive": "When metal organic frameworks turn into linear magnets: We investigate the existence of linear magnetism in the metal organic\nframework materials MOF-74-Fe, MOF-74-Co, and MOF-74-Ni, using first-principles\ndensity functional theory. MOF-74 displays regular quasi-linear chains of\nopen-shell transition metal atoms, which are well separated. Our results show\nthat within these chains-for all three materials-ferromagnetic coupling of\nsignificant strength occurs. In addition, the coupling in-between chains is at\nleast one order of magnitude smaller, making these materials almost perfect 1D\nmagnets at low temperature. The inter-chain coupling is found to be\nanti-ferromagnetic, in agreement with experiments. While some quasi-1D\nmaterials exist that exhibit linear magnetism-mostly complex oxides, polymers,\nand a few other rare material-they are typically very difficult to synthesize.\nThe significance of our finding is that MOF-74 is very easy to synthesize and\nit is likely the simplest realization of the 1D Ising model in nature. MOF-74\ncould thus be used in future experiments to study 1D magnetism at low\ntemperature."
    },
    {
        "anchor": "Orbital-polarization terms: from a phenomenological to a\n  first-principles description of orbital magnetism in density-functional\n  theory: Phenomenological orbital-polarization (OP) terms have been repeatedly\nintroduced in the single-particle equations of spin-density-functional theory,\nin order to improve the description of orbital magnetic moments in systems\ncontaining transition metal ions. Here we show that these ad hoc corrections\ncan be interpreted as approximations to the exchange-correlation vector\npotential A_xc of current-density-functional theory (CDFT). This connection\nprovides additional information on both approaches: Phenomenological OP terms\nare connected to first-principles theory, leading to a rationale for their\nempirical success and a reassessment of their limitations and the\napproximations made in their derivation. Conversely, the connection of OP terms\nwith CDFT leads to a set of simple approximations to the CDFT potential A_xc,\nwith a number of desirable features that are absent from electron-gas-based\nfunctionals.",
        "positive": "High density nonmagnetic cobalt in thin films: Recently high density (HD) nonmagnetic (NM) cobalt has been discovered in a\ncobalt thin film, grown on Si(111). This cobalt film had a natural cobalt oxide\nat the top. The oxide layer forms when the film is taken out of the\nelectron-beam deposition chamber and exposed to air. Thin HD NM cobalt layers\nwere found near the cobalt/silicon and the cobalt-oxide/cobalt interfaces,\nwhile the thicker mid-depth region of the film was hcp cobalt with normal\ndensity and normal magnetic moment. If an ultrathin film of gold is grown on\nthe cobalt layer, before exposing it to air, the oxidation of the cobalt\nsurface layer is prevented. It is important to investigate whether the growth\nof HD NM cobalt layers in the thin film depends on (i) capping of the film by\nthe gold layer, (ii) the film thickness and (iii) the nature of the substrate.\nThe results of such investigations, presented here, indicates that for cobalt\nfilms capped with a thin gold layer, and for various film thicknesses, HD NM\ncobalt layers are still observed. However, instead of a Si substrate, when the\ncobalt films are grown on oxide substrates, such as silicon oxide or cobalt\noxide, HD NM cobalt layers are not observed."
    },
    {
        "anchor": "Critical Ruptures: The fracture of materials is a catastrophic phenomenon of considerable\ntechnological and scientific importance. Here, we analysed experiments designed\nfor industrial applications in order to test the concept that, in heterogeneous\nmaterials such as fiber composites, rocks, concrete under compression and\nmaterials with large distributed residual stresses, rupture is a genuine\ncritical point, i.e. the culmination of a self-organization of damage and\ncracking characterized by power law signatures. Specifically, we analyse the\nacoustic emissions recorded during the pressurisation of spherical tanks of\nkevlar or carbon fibers pre-impregnated in a resin matrix wrapped up around a\nthin metallic liner (steel or titanium) fabricated and instrumented by\nA\\'erospatiale-Matra Inc. These experiments are performed as part of a routine\nindustrial procedure which tests the quality of the tanks prior to shipment and\nvaries in nature. We find that the seven acoustic emission recordings of seven\npressure tanks which was brought to rupture exhibit clear acceleration in\nagreement with a power law ``divergence'' expected from the critical point\ntheory. In addition, we find strong evidence of log-periodic corrections that\nquantify the intermittent succession of accelerating bursts and quiescent\nphases of the acoustic emissions on the approach to rupture. An improved model\naccounting for the cross-over from the non-critical to the critical region\nclose to the rupture point exhibits interesting predictive potential.",
        "positive": "Covalent functionalization of strained graphene: Enhancement of the chemical activity of graphene is evidenced by\nfirst-principles modelling of chemisorption of the hydrogen, fluorine, oxygen\nand hydroxyl groups on strained graphene. For the case of negative strain or\ncompression, chemisorption of the single hydrogen, fluorine or hydroxyl group\nis energetically more favourable than those of their pairs on different\nsublattices. This behaviour stabilizes the magnetism caused by the\nchemisorption being against its destruction by the pair formations. Initially\nflat, compressed graphene is shown to buckle spontaneously right after\nchemisorption of single adatoms. Unlike hydrogenation or fluorination, the\noxidation process turns from the endothermic to exothermic for all types of the\nstrain and depends on the direction of applied strains. Such properties will be\nuseful in designing graphene devices utilizing functionalization as well as\nmechanical strains."
    },
    {
        "anchor": "Transforming nonlocality into frequency dependence: a shortcut to\n  spectroscopy: Measurable spectra are theoretically very often derived from complicated\nmany-body Green's functions. In this way, one calculates much more information\nthan actually needed. Here we present an in principle exact approach to\nconstruct effective potentials and kernels for the direct calculation of\nelectronic spectra. In particular, the potential that yields the spectral\nfunction needed to describe photoemission turns out to be dynamical but {\\it\nlocal} and {\\it real}. As example we illustrate this ``photoemission\npotential'' for sodium and aluminium, modelled as homogeneous electron gas, and\ndiscuss in particular its frequency dependence stemming from the nonlocality of\nthe corresponding self-energy. We also show that our approach leads to a very\nshort derivation of a kernel that is known to well describe absorption and\nenergy-loss spectra of a wide range of materials.",
        "positive": "Epitaxial Growth of Spinel Cobalt Ferrite Films on MgAl$_2$O$_4$\n  Substrates by Direct Liquid Injection Chemical Vapor Deposition: The direct liquid injection chemical vapor deposition (DLI-CVD) technique has\nbeen used for the growth of cobalt ferrite (CFO) films on (100)-oriented\nMgAl$_2$O$_4$ (MAO) substrates. Smooth and highly epitaxial cobalt ferrite thin\nfilms, with the epitaxial relationship $\\mathrm{MAO} (100)\\:[001] \\parallel\n\\mathrm{CFO} (100)\\:[001]$, are obtained under optimized deposition conditions.\nThe films exhibit bulk-like structural and magnetic properties with an\nout-of-plane lattice constant of $8.370\\;\\mathrm{\\AA}$ and a saturation\nmagnetization of $420\\;\\mathrm{kA/m}$ at room temperature. The Raman spectra of\nfilms on MgAl$_2$O$_4$ support the fact that the Fe$^{3+}$- and the\nCo$^{2+}$-ions are distributed in an ordered fashion on the B-site of the\ninverse spinel structure. The DLI-CVD technique has been extended for the\ngrowth of smooth and highly oriented cobalt ferrite thin films on a variety of\nother substrates, including MgO, and piezoelectric lead magnesium niobate-lead\ntitanate and lead zinc niobate-lead titanate substrates."
    },
    {
        "anchor": "Giant AC magnetoresistance and anisotropic AC magnetoresistance in\n  granular magnetic alloys: (withdrawn)AC resistance of melt-spun granular magnetic Cu85Co15 ribbons was\nmeasured as a function of temperature in the range 5-300 K, magnetic field Hdc\nin the range -60 kOe to 60 kOe, and frequency in the range 1-1000 Hz. A sharp\npeak of zero-field resistance, which scales with frequency, and an associated\nisotropic giant AC magnetoresistance in small fields are observed around the\ntemperature of collective freezing of interacting magnetic moments. Anomalous\nbehavior of AC resistance in large fields (Hdc > 20 kOe) is observed in a much\nbroader temperature range. This effect is not only frequency- dependent, but\nalso highly sensitive to anisotropy. We call it anisotropic AC\nmagnetoresistance.",
        "positive": "First stages of the InP(1 0 0) surfaces nitridation studied by AES, EELS\n  and EPES: The nitrides of group III metals: AlN, GaN and InN are very important\nmaterials due to their applications for short wavelength opto-electronics\n(light-emitting diodes and laser diodes). It is essential for the realization\nof such novel devices to grow high-quality nitride single crystals. In this\npaper, we report the first stages of the InP(1 0 0) surfaces nitridation in\norder to grow high-quality nitride films. Indeed, the nitridation process is an\nimportant step in the growth of nitrides [J. Vac. Sci. Technol. A 17 (1999)\n2194; Phys. Status Solidi A 176 (1999) 595]. Previous works [Synth. Met. 90\n(1997) 2233; Appl. Phys. Lett. 63 (1993) 1957] have shown that in situ Ar+ ions\nbombardment is useful on the one hand to clean the surface, and on the other\nhand to create droplets of metallic indium in well-controlled quantity. Then\nthe indium metallic enrichment of the surface, monitoring by elastic peak\nelectron spectroscopy (EPES) and Auger electron spectroscopy (AES) allows to\nprepare the III-V semiconductors surfaces to the nitridation step. The\nnitridated process has been performed with a high voltage plasma discharge cell\nand has been studied using quantitative Auger electron spectroscopy, elastic\npeak electron spectroscopy and electron energy loss spectroscopy (EELS), in\norder to optimize the conditions of InN layers formation."
    },
    {
        "anchor": "Comparing the Corrosion of Uranium Nitride and Uranium Dioxide Surfaces\n  with H2O2: Uranium mononitride, UN, is considered a potential accident tolerant fuel due\nto its high uranium density, high thermal conductivity, and high melting point.\nCompared with the relatively inert UO2, UN has a high reactivity in water,\nhowever, studies have not considered the significant effect of radiation, which\nis known to cause corrosion of UO2. This study uses 0.1 M H2O2 to simulate the\neffects of water radiolysis in order to compare the radiolytic corrosion rates\nof UO2, UN, and U2N3 thin films at room temperature. X-ray reflectivity was\nused to investigate the changes in film morphology as a function of H2O2\nexposure time, allowing changes in film thickness and roughness to be observed\non the Angstrom length-scale. Results showed significant differences between\nUO2, UN, and U2N3, with corrosion rates of 0.083(3), 0.020(4), and 0.47(8) A/s,\nrespectively, showing that UN corrodes more slowly than UO2 in 0.1 M H2O2.",
        "positive": "Grain boundary-induced martensitic transformations: A phase-field study\n  of nucleation, size-effect, triple junction-effect, microstructures, and\n  compatibility at the nanoscale: An original thermodynamically consistent large strains-based multiphase\nphase-field (PF) approach of Ginzburg-Landau type is developed for studying the\ngrain boundary (GB)-induced martensitic transformations (MTs) in\npolycrystalline materials at the nanoscale considering the structural stresses\nwithin the interfaces. In this general PF approach, N independent order\nparameters are used for describing the austenite (A)<->martensite (M)\ntransformations and N(>1) martensitic variants, and another M independent order\nparameters are considered for describing M(>1) grains in the polycrystalline\nsamples. The change in the GB energy due to its structural rearrangement during\nMTs is considered using variable energy for the GB(s) as a function of the\norder parameter related to the A<->M transformation. A rich plot for the\ntemperatures of transformations between the A, premartensite, and M in a\nbicrystal with a symmetric planar tilt GB are plotted for the varying\naustenitic GB width. The strong effects of the parameters, including the\naustenitic GB width, change in GB energy due to MTs, GB misorientation, applied\nstrains, and sample size on heterogeneous nucleation of the phases and the\nsubsequent complex martensitic microstructures evolution are explored in\nvarious bicrystals with symmetric or asymmetric planar or circular tilt GBs\nduring the forward and reverse transformations. The triple junction (TJ) energy\nand the energy and width of the adjacent GBs are also shown to strongly\ninfluence the nucleation and microstructures using the tricrystals having three\nsymmetric planar tilt GBs. The compatibility of the microstructures across the\nGBs is studied. The elastic and structural stresses across the GBs and TJ\nregions are plotted, which is essential for understanding the role of GBs and\nTJs in materials failure."
    },
    {
        "anchor": "Reconstruction of \u00c5ngstr\u00f8m resolution exit-waves by the\n  application of drift-corrected phase-shifting off-axis electron holography: Phase-shifting electron holography is an excellent method to reveal electron\nwave phase information with very high phase sensitivity over a large range of\nspatial frequencies. It circumvents the limiting trade-off between fringe\nspacing and visibility of standard off-axis holography. Previous\nimplementations have been limited by the independent drift of biprism and\nsample. We demonstrate here an advanced drift correction scheme for the\nhologram series that allow to obtain reliable phase information at the 1 {\\AA}\ninformation limit of the used Titan 80-300 kV environmental transmission\nelectron microscope using a single biprism at moderate voltage of 250 V. The\nobtained phase and amplitude information is validated at a thin Pt sample by\nuse of multislice image simulation with the frozen lattice approximation and\nshows excellent agreement. The presented method drastically reduces the\nhardware requirements and thus allows to achieve high resolution in off-axis\nholography in various instruments including those for in-situ applications. A\nsoftware implementation for the acquisition, calibration and reconstruction is\nprovided.",
        "positive": "Contact of Single Asperities with Varying Adhesion: Comparing Continuum\n  Mechanics to Atomistic Simulations: Atomistic simulations are used to test the equations of continuum contact\nmechanics in nanometer scale contacts. Nominally spherical tips, made by\nbending crystals or cutting crystalline or amorphous solids, are pressed into a\nflat, elastic substrate. The normal displacement, contact radius, stress\ndistribution, friction and lateral stiffness are examined as a function of load\nand adhesion. The atomic scale roughness present on any tip made of discrete\natoms is shown to have profound effects on the results. Contact areas, local\nstresses, and the work of adhesion change by factors of two to four, and the\nfriction and lateral stiffness vary by orders of magnitude. The microscopic\nfactors responsible for these changes are discussed. The results are also used\nto test methods for analyzing experimental data with continuum theory to\ndetermine information, such as contact area, that can not be measured directly\nin nanometer scale contacts. Even when the data appear to be fit by continuum\ntheory, extracted quantities can differ substantially from their true values."
    },
    {
        "anchor": "Bayesian Active Learning for Scanning Probe Microscopy: from Gaussian\n  Processes to Hypothesis Learning: Recent progress in machine learning methods, and the emerging availability of\nprogrammable interfaces for scanning probe microscopes (SPMs), have propelled\nautomated and autonomous microscopies to the forefront of attention of the\nscientific community. However, enabling automated microscopy requires the\ndevelopment of task-specific machine learning methods, understanding the\ninterplay between physics discovery and machine learning, and fully defined\ndiscovery workflows. This, in turn, requires balancing the physical intuition\nand prior knowledge of the domain scientist with rewards that define\nexperimental goals and machine learning algorithms that can translate these to\nspecific experimental protocols. Here, we discuss the basic principles of\nBayesian active learning and illustrate its applications for SPM. We progress\nfrom the Gaussian Process as a simple data-driven method and Bayesian inference\nfor physical models as an extension of physics-based functional fits to more\ncomplex deep kernel learning methods, structured Gaussian Processes, and\nhypothesis learning. These frameworks allow for the use of prior data, the\ndiscovery of specific functionalities as encoded in spectral data, and\nexploration of physical laws manifesting during the experiment. The discussed\nframework can be universally applied to all techniques combining imaging and\nspectroscopy, SPM methods, nanoindentation, electron microscopy and\nspectroscopy, and chemical imaging methods, and can be particularly impactful\nfor destructive or irreversible measurements.",
        "positive": "Correlating Nanocrystalline Structure with Electronic Properties in 2D\n  Platinum Diselenide: Platinum diselenide (PtSe${_2}$) is a two-dimensional (2D) material with\noutstanding electronic and piezoresistive properties. The material can be grown\nat low temperatures in a scalable manner which makes it extremely appealing for\nmany potential electronics, photonics, and sensing applications. Here, we\ninvestigate the nanocrystalline structure of different PtSe${_2}$ thin films\ngrown by thermally assisted conversion (TAC) and correlate them with their\nelectronic and piezoresistive properties. We use scanning transmission electron\nmicroscopy for structural analysis, X-ray photoelectron spectroscopy (XPS) for\nchemical analysis, and Raman spectroscopy for phase identification. Electronic\ndevices are fabricated using transferred PtSe${_2}$ films for electrical\ncharacterization and piezoresistive gauge factor measurements. The variations\nof crystallite size and their orientations are found to have a strong\ncorrelation with the electronic and piezoresistive properties of the films,\nespecially the sheet resistivity and the effective charge carrier mobility. Our\nfindings may pave the way for tuning and optimizing the properties of TAC-grown\nPtSe${_2}$ towards numerous applications."
    },
    {
        "anchor": "Quantifying Li-content for compositional tailoring of lithium ferrite\n  ceramics: Owing to their multiple applications, lithium ferrites are relevant materials\nfor several emerging technologies. For instance, LiFeO2 has been spotted as an\nalternative cathode material in Li-ion batteries, while LiFe5O8 is the lowest\ndamping ferrite, holding promise in the field of spintronics. The Li-content in\nlithium ferrites has been shown to greatly affect the physical properties, and\nin turn, the performance of functional devices based on these materials.\nDespite this, lithium content is rarely accurately quantified, as a result of\nthe low number of electrons in Li hindering its identification by means of\nroutine materials characterization methods. In the present work, magnetic\nlithium ferrite powders with Li:Fe ratios of 1:1, 1:3 and 1:5 have been\nsynthesized, successfully obtaining phase-pure materials (LiFeO2 and LiFe5O8),\nas well as a controlled mixture of both phases. The powders have been compacted\nand subsequently sintered by thermal treatment (Tmax = 1100 {\\deg}C) to\nfabricate dense pellets which preserve the original Li:Fe ratios. Li-content on\nboth powders and pellets has been determined by two independent methods: (i)\nRutherford backscattering spectroscopy combined with nuclear reaction analysis\nand (ii) Rietveld analysis of powder X-ray diffraction data. With good\nagreement between both techniques, it has been confirmed that the Li:Fe ratios\nemployed in the synthesis are maintained in the sintered ceramics. The same\nconclusion is drawn from spatially-resolved confocal Raman microscopy\nexperiments on regions of a few microns. Field emission scanning electron\nmicroscopy has evidenced the substantial grain growth taking place during the\nsintering process - mean particle sizes rise from about 600 nm in the powders\nup to 3.8(6) um for dense LiFeO2 and 10(2) um for LiFe5O8 ceramics.",
        "positive": "Quasi-Stable Structures in Equilibrium Dense Bismuth Melt: Experimental\n  and First Principles Theoretical Studies: Near the melting temperature, equilibrium bismuth melt is characterized by\nstructural features that are absent in equilibrium monatomic simple liquids. In\nthe present work, the structure of bismuth melt is studied by X-ray diffraction\nexperiments and quantum chemical calculations. The presence of quasi-stable\nstructures in the melt has been found, the lifetime of which exceeds the\nstructural relaxation time of this melt. It is shown that these structures are\ncharacterized by a low degree of ordering and spatial localisation. It was\nfound that up to $50$\\% of the atoms in the melt can be involved in the\nformation of these structures. The elementary structural units of these\nstructures are triplets of regular geometry with the characteristic lengths\n$3.25$ \\AA~and $4.7$ \\AA~as well as with the characteristic angles $45^{\\circ}$\nand $90^{\\circ}$. The characteristic lengths of these triplets are fully\nconsistent with correlation lengths associated with the short-range order in\nbismuth melt."
    },
    {
        "anchor": "Substrate-Independent Growth of Atomically Precise Chiral Graphene\n  Nanoribbons: Contributing to the need of new graphene nanoribbon (GNR) structures that can\nbe synthesized with atomic precision, we have designed a reactant that renders\nchiral (3,1) - GNRs after a multi-step reaction including Ullmann coupling and\ncyclodehydrogenation. The nanoribbon synthesis has been successfully proved on\ndifferent coinage metals, and the formation process, together with the\nfingerprints associated to each reaction step, has been studied combining\nscanning tunnelling microscopy, core-level spectroscopy and density functional\ncalculations. In addition to the GNR chiral edge structure, the substantial GNR\nlengths achieved and the low processing temperature required to complete the\nreaction grant this reactant extremely interesting properties for potential\napplications.",
        "positive": "Graphene Helicoid: The Distinct Properties Promote Application of\n  Graphene Related Materials in Thermal Management: The extremely high thermal conductivity of graphene has received great\nattention both in experiments and calculations. Obviously, new feature in\nthermal properties is of primary importance for application of graphene-based\nmaterials in thermal management in nanoscale. Here, we studied the thermal\nconductivity of graphene helicoid, a newly reported graphene-related\nnanostructure, using molecular dynamics simulation. Interestingly, in contrast\nto the converged cross-plane thermal conductivity in multi-layer graphene,\naxial thermal conductivity of graphene helicoid keeps increasing with thickness\nwith a power law scaling relationship, which is a consequence of the divergent\nin-plane thermal conductivity of two-dimensional graphene. Moreover, the large\noverlap between adjacent layers in graphene helicoid also promotes higher\nthermal conductivity than multi-layer graphene. Furthermore, in the small\nstrain regime (< 10%), compressive strain can effectively increase the thermal\nconductivity of graphene helicoid, while in the ultra large strain regime\n(~100% to 500%), tensile strain does not decrease the heat current, unlike that\nin generic solid-state materials. Our results reveal that the divergence in\nthermal conductivity, associated with the anomalous strain dependence and the\nunique structural flexibility, make graphene helicoid a new platform for\nstudying fascinating phenomena of key relevance to the scientific understanding\nand technological applications of graphene-related materials."
    },
    {
        "anchor": "The Force Field for Amino Acid Based Ionic Liquids: Polar Residues: Ionic liquids (ILs) constitute one of the most active fields of research\nnowadays. Many organic and inorganic molecules can be converted into ions via\nrelatively simple procedures. These ions can be combined into ILs. Amino acid\nbased ILs (AAILs) represent a specific interest due to solubilization of\nbiological species, participation in enzymatic catalysis, and capturing toxic\ngases. We develop a new force field (FF) for the seven selected AAILs\ncomprising 1-ethyl-3-methylimidazolium cation and amino acid anions with polar\nresidues. The anions were obtained via deprotonation of carboxyl group. We\naccount for peculiar interactions between the anion and the cation by fitting\nelectrostatic potential for an ion pair, in contrast to isolated ions. The van\nder Waals interactions were transferred from the CHARMM36 FF with minor\nmodifications, as suggested by hybrid density functional theory. Compatibility\nbetween our parameters and CHARMM36 parameters is preserved. The developed\ninteraction model fosters computational investigation of ionic liquids.",
        "positive": "Modified Electron Beam Induced Deposition of Metal Nanostructure Arrays\n  using a Parallel Electron Beam: A modified electron beam induced deposition method using a parallel beam of\nelectrons is developed. The method relies on the build-up of surface potential\non an insulating surface exposed to an electron beam. Presence of sharp edges\non the insulating surface implies presence of large electric fields that lead\nto site-specific nucleation of metal vapor on those regions. Feature sizes as\nsmall as 20 nm can be deposited without the need to use fine probes and thus\nthe limitation of probe size imposed on the resolution is overcome. The use of\npure metal vapor also renders the process inherently clean."
    },
    {
        "anchor": "Structure and magnetic properties of a\n  La$_{0.75}$Sr$_{0.25}$Cr$_{0.90}$O$_{3-\u03b4}$ single crystal: We have successfully grown large and good-quality single crystals of the\nLa$_{0.75}$Sr$_{0.25}$Cr$_{0.90}$O$_{3-\\delta}$ compound using the\nfloating-zone method with laser diodes. We investigated the crystal quality,\ncrystallography, chemical composition, magnetic properties and the oxidation\nstate of Cr in the grown single crystals by employing a combination of\ntechniques, including X-ray Laue and powder diffraction, scanning electron\nmicroscopy, magnetization measurements, X-ray photoelectron spectroscopy and\nlight absorption. The La$_{0.75}$Sr$_{0.25}$Cr$_{0.90}$O$_{3-\\delta}$ single\ncrystal exhibits a single-phase composition, crystallizing in a trigonal\nstructure with the space group $R\\bar{3}c$ at room temperature. The chemical\ncomposition was determined as La$_{0.75}$Sr$_{0.25}$Cr$_{0.90}$O$_{3-\\delta}$,\nindicating a significant chromium deficiency. Upon warming, we observed five\ndistinctive characteristic temperatures, namely $T_1 =$ 21.50(1) K, $T_2 =$\n34.98(1) K, $T_3 =$ 117.94(1) K, $T_4 =$ 155.01(1) K, and $T_{\\textrm{N}} =$\n271.80(1) K, revealing five distinct magnetic anomalies. Our magnetization\nstudy allows us to explore the nature of these anomalies. Remarkably, the\noxidation state of chromium in the single-crystal\nLa$_{0.75}$Sr$_{0.25}$Cr$_{0.90}$O$_{3-\\delta}$, characterized by a band gap of\n1.630(8) eV, is exclusively attributed to Cr$^{3+}$ ions, making a departure\nfrom the findings of previous studies on polycrystalline materials.",
        "positive": "Lock-in detection for pulsed electrically detected magnetic resonance: We show that in pulsed electrically detected magnetic resonance (pEDMR)\nsignal modulation in combination with a lock-in detection scheme can reduce the\nlow-frequency noise level by one order of magnitude and in addition removes the\nmicrowave-induced non-resonant background. This is exemplarily demonstrated for\nspin-echo measurements in phosphorus-doped Silicon. The modulation of the\nsignal is achieved by cycling the phase of the projection pulse used in pEDMR\nfor the read-out of the spin state."
    },
    {
        "anchor": "Electronic properties of SnTe-class topological crystalline insulator\n  materials: The rise of topological insulators in recent years has broken new ground both\nin the conceptual cognition of condensed matter physics and the promising\nrevolution of the electronic devices. It also stimulates the explorations of\nmore topological states of matter. Topological crystalline insulator is a new\ntopological phase, which combines the electronic topology and crystal symmetry\ntogether. In this article, we review the recent progress in the studies of\nSnTe-class topological crystalline insulator materials. Starting from the\ntopological identifications in the aspects of the bulk topology, surface states\ncalculations and experimental observations, we present the electronic\nproperties of topological crystalline insulators under various perturbations,\nincluding native defect, chemical doping, strain, and thickness-dependent\nconfinement effects, and then discuss their unique quantum transport\nproperties, such as valley-selective filtering and helicity-resolved\nfunctionalities for Dirac fermions. The rich properties and high tunability\nmake SnTe-class materials promising candidates for novel quantum devices.",
        "positive": "MXenes: The key to unlocking the potential metal-ion batteries -- review: The invention of next-generation electrochemical energy devices (EEDs) has\nled to concerns about range anxiety, long recharge times, and moderate energy\ndensity. The behavior of cells and packs during fast charging depends on\nvarious factors, categorized into charging strategies and new materials. MXenes\nhave gained significant attention since their discovery in 2011 due to their\nunique physical, chemical, and mechanical properties. Drexel researchers\nexplored their use in batteries, where they offer advantages in high rates and\npower compared to other energy storage materials. However, the commercial use\nof MXenes in large volumes poses a challenge. This paper focuses on the\nstructure, synthesis, and applications of MXenes in metal-ion batteries."
    },
    {
        "anchor": "Two-dimensional bimolecular recombination in amorphous organic\n  semiconductors: We consider the two-dimensional bimolecular recombination of charge carriers\nin amorphous organic semiconductors having the lamellar structure. We calculate\nthe dependence of the effective recombination rate constant on the carrier\ndensity taking into account the correlated nature of the energetic disorder\ntypical for organic semiconductors. Resulting recombination kinetics\ndemonstrates a very rich variety of behaviors depending on the correlation\nproperties of the particular semiconductor and relevant charge density range.",
        "positive": "Surface Reconstructions and Bonding via the Electron Localization\n  Function: The Case of Si(001): The bonding pattern of a covalent semiconductor is disrupted when a surface\nis cut while keeping a rigid (truncated bulk) geometry. The covalent bonds are\npartly reformed (with a sizeable energy gain) when reconstruction is allowed.\nWe show that the ``electron localization function'' (ELF)---applied within a\nfirst--principles pseudopotential framework---provides un unprecedented insight\ninto the bonding mechanisms. In the unreconstructed surface one detects a\npartly metallic character, which disappears upon reconstruction. In the surface\nreformed bonds, the ELF sharply visualizes strongly paired electrons, similar\nin character to those of the bulk bonds."
    },
    {
        "anchor": "Magnetocrystalline Anisotropy and the Magnetocaloric Effect in Fe2P: Magnetic and magnetocaloric properties of high-purity, giant magnetocaloric\npolycrystalline and single-crystalline Fe2P are investigated. Fe2P displays a\nmoderate magnetic entropy change which spans over 70 K and the presence of\nstrong magnetization anisotropy proves this system is not fully itinerant but\ndisplays a mix of itinerant and localized magnetism. The properties of pure\nFe2P are compared to those of giant magnetocaloric (Fe,Mn)2(P,A) compounds\nhelping understand the exceptional characteristics shown by the latter which\nare so promising for heat pump and energy conversion applications.",
        "positive": "Photoinduced charge density wave transition like a puppet on a string: Charge density wave (CDW) materials can undergo an ultrafast phase transition\nafter an ultrashort laser pulse excitation, and the suggested underlying\nmechanisms have always been associated with two main features: excitonic\ninteraction-induced CDW charge order and electron-phonon coupling-induced\nperiodic lattice distortion (PLD). Here, beyond these two mechanisms, we reveal\nthat photoexcitation induced CDW phase transition in the prototypic CDW example\n1T-TiSe2 is similar to a puppet on a string: six Ti-Se bonds connected to each\ndistorted Ti atom acting as six strings controlling the PLD and in turn the CDW\norders. The photoexcitation induced modulation on charge population of the\nTi-Se bonds generates a laser-fluence-dependent interatomic-repulsive force\nalong each Ti-Se bond. The nonequal length of these six Ti-Se bonds gives rise\nto a net force exerted on the central distorted Ti atom to push it toward the\nsuppressing of the PLD and thus the CDW orders. We further illustrate that the\ndynamics of each distorted Ti atom behaves as though it attached to a spring in\na simple harmonic motion with a fluence-dependent oscillation frequency,\nuniting two previously reported scaling laws for phase transition time. These\nfindings significantly advance the understanding of CDW instability and provide\nnew insights into how photoexcitation induced modulation on charge population\nmay lead to phase transitions by directly connecting interatomic forces with\nreaction pathways."
    },
    {
        "anchor": "Graphene on metallic surfaces: problems and perspectives: The present manuscript summarizes the modern view on the problem of the\ngraphene-metal interaction. Presently, the close-packed surfaces of d metals\nare used as templates for the preparation of highly-ordered graphene layers.\nDifferent classifications can be introduced for these systems: graphene on\nlattice-matched and graphene on lattice-mismatched surfaces where the\ninteraction with the metallic substrate can be either \"strong\" or \"weak\". Here\nthese classifications, with the focus on the specific features in the\nelectronic structure in all cases, are considered on the basis of large amounts\nof experimental and theoretical data, summarized and discussed. The\nperspectives of the graphene-metal interface in fundamental and applied physics\nand chemistry are pointed out.",
        "positive": "First-principles GW-BSE excitations in organic molecules: We present a first-principles method for the calculation of optical\nexcitations in nanosystems. The method is based on solving the Bethe-Salpeter\nequation (BSE) for neutral excitations. The electron self-energy is evaluated\nwithin the GW approximation, with dynamical screening effects described within\ntime-dependent density-functional theory in the adiabatic, local approximation.\nThis method is applied to two systems: the benzene molecule, C$_6$H$_6$, and\nazobenzene, C$_{12}$H$_{10}$N$_2$. We give a description of the\nphotoisomerization process of azobenzene after an $n-\\pi^\\star$ excitation,\nwhich is consistent with multi-configuration calculations."
    },
    {
        "anchor": "Symmetry Effects on Nonlocal Electron-Phonon Coupling in Organic\n  Semiconductors: The electronic and electrical properties of crystalline organic\nsemiconductors, such as the dispersions of the electronic bands and the\ndependence of charge-carrier mobility on temperature, are greatly impacted by\nthe nonlocal electron-phonon interactions associated with intermolecular\nlattice vibrations. Here, we present a theoretical description that underlines\nthat these properties vary differently as a function of the symmetry of the\nnonlocal electron-phonon coupling mechanism. The electron-phonon coupling\npatterns in real space are seen to have a direct and significant impact on the\ninteractions in reciprocal space. Our findings demonstrate the importance of\naspects that are usually missing in current transport models. Importantly, an\nadequate description of the electronic and charge-transport properties of\norganic semiconductors requires that the models take into account both\nantisymmetric and symmetric contributions to the nonlocal electron-phonon\ncoupling mechanism.",
        "positive": "Investigating the basis set convergence of diagrammatically decomposed\n  coupled-cluster correlation energy contributions for the uniform electron gas: We investigate the convergence of coupled-cluster correlation energies and\nrelated quantities with respect to the employed basis set size for the uniform\nelectron gas to gain a better understanding of the basis set incompleteness\nerror. To this end, coupled-cluster doubles (CCD) theory is applied to the\nthree dimensional uniform electron gas for a range of densities, basis set\nsizes and electron numbers. We present a detailed analysis of individual,\ndiagrammatically decomposed contributions to the amplitudes at the level of CCD\ntheory. In particular, we show that only two terms from the amplitude equations\ncontribute to the asymptotic large-momentum behavior of the transition\nstructure factor, corresponding to the cusp region at short interelectronic\ndistances. However, due to the coupling present in the amplitude equations, all\ndecomposed correlation energy contributions show the same asymptotic\nconvergence behavior to the complete basis set limit. These findings provide an\nadditional rationale for the success of a recently proposed correction to the\nbasis set incompleteness error (BSIE) of coupled-cluster theory. Lastly, we\nexamine the BSIE in the coupled-cluster doubles plus perturbative triples\n[CCD(T)] method, as well as in the newly proposed coupled-cluster doubles plus\ncomplete perturbative triples [CCD(cT)] method."
    },
    {
        "anchor": "Degradation by Exposure of Co-Evaporated CH3NH3PbI3 Thin Films: Degradation of co-evaporated CH3NH3PbI3 thin films was investigated with\nx-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD) as the films\nwere subjected to exposure of oxygen, dry air, ambient, or H2O. The\nco-evaporated thin films have consistent stoichiometry and crystallinity\nsuitable for detailed surface analysis. The results indicate that CH3NH3PbI3 is\nnot sensitive to oxygen. Even after 10^13 Langmuire (L, one L equals 10^-6 torr\nsec) oxygen exposure, no O atoms could be found on the surface. The film is not\nsensitive to dry air as well. A reaction threshold of about 2*10^10 L is found\nfor H2O exposure, below which no CH3NH3PbI3 degradation takes place and the H2O\nacts as an n-dopant. Above the threshold, the film begins to decompose, and the\namount of N and I decrease quickly, leaving the surface with PbI2, amorphous C\nand O contamination.",
        "positive": "Boron-doping of cubic SiC for intermediate band solar cells: a scanning\n  transmission electron microscopy study: Boron (B) has the potential for generating an intermediate band in cubic\nsilicon carbide (3C-SiC), turning this material into a highly efficient\nabsorber for single-junction solar cells. The formation of a delocalized band\ndemands high concentration of the foreign element, but the precipitation\nbehavior of B in the 3C polymorph of SiC is not well known. Here,\nprobe-corrected scanning transmission electron microscopy and secondary-ion\nmass spectrometry are used to investigate precipitation mechanisms in\nB-implanted 3C-SiC as a function of temperature. Point-defect clustering was\ndetected after annealing at 1273 K, while stacking faults, B-rich precipitates\nand dislocation networks developed in the 1573 - 1773 K range. The precipitates\nadopted the rhombohedral B13C2 structure and trapped B up to 1773 K. Above this\ntemperature, higher solubility reduced precipitation and free B diffused out of\nthe implantation layer. Dopant concentrations E19 at.cm-3 were achieved at 1873\nK."
    },
    {
        "anchor": "Direct Observation of Mono-, Bi-, and Tri-layer Charge Density Waves in\n  1T-TaS_2 by Transmission Electron Microscopy without a Substrate: Charge-density-waves (CDW) which occur mainly in low-dimensional systems have\na macroscopic wave function similar to superfluids and superconductors.\nKosterlitz-Thouless (KT) transition is observed in superfluids and\nsuperconductors, but the presence of KT transition in ultra-thin CDW systems\nhas been an open problem. We report the direct real-space observation of CDWs\nwith new order states in mono-, bi-, and tri-layer 1T-TaS_2 crystal by using a\nlow voltage scanning-transmission-electron-microscope (STEM) without a\nsubstrate. This method is ideal to observe local atomic structures and possible\ndefects. We clearly observed that the mono-layer crystal has a new triclinic\nstripe CDW order without the triple q condition q_1 + q_2 + q_3 = 0. A strong\nelectron-phonon interaction gives rise to new crevasse (line) type defects\ninstead of disclination (point) type defects due to the KT transition. These\nresults reaffirm the importance of the electron-phonon interaction in\nmono-layer nanophysics.",
        "positive": "First-principles study of the structural and electronic properties of\n  BN-ring doped graphene: Since advanced Silicon-based device components are moderately chemically\ntunable, doped graphene has emerged as a promising candidate to replace this\nsemiconducting material in flexible miniaturized electronic devices. Indeed,\nheteroatom co-doping (i.e. with boron and/or nitrogen) is an appealing strategy\nto tune both its structural and electronic properties, possibly inducing a band\ngap in graphene. However, presently synthesized BN-doped carbon-based materials\nare randomly doped, leading to their electronic properties not being\nreproducible. Using first-principles techniques, the present study investigates\nthe periodic doping of graphene with borazine-like rings in order to search for\nan entirely new class of BCN hybrid 2D materials exhibiting high stabilities\nand optimized band gaps for opto-electronic applications. Ab initio\ncalculations show that BN-ring doped graphene displays cohesive energies\ncomparable with benchmark ideal periodic BCN systems (such as BC$_3$,\nC$_3$N$_4$, BC$_2$N) with a decreasing linear trend toward high concentrations\nof BN-rings. Band gaps of BN-ring doped graphene systems are calculated using\nmany-body perturbation techniques and are found to be sensitive to the doping\npattern and to be considerably larger for high concentrations of BN rings\nexhibiting the same orientation. These predictions suggest that BN-ring doped\ngraphene materials could be interesting candidates for the next generation of\noptoelectronic devices and open new opportunities for their synthesis using\nchemical bottom-up approaches."
    },
    {
        "anchor": "ELATE: An open-source online application for analysis and visualization\n  of elastic tensors: We report on the implementation of a tool for the analysis of second-order\nelastic stiffness tensors, provided with both an open-source Python module and\na standalone online application providing visualization tools of anisotropic\nmechanical properties. After describing the software features, how we compute\nthe conventional elastic constants and how we represent them graphically, we\nexplain our technical choices for the implementation. In particular, we focus\non why a Python module is used to generate the HTML web page with embedded\nJavascript for dynamical plots.",
        "positive": "Molecular dynamics of halogenated graphene - hexagonal boron nitride\n  nanoribbons: The hybrid graphene - hexagonal boron nitride (G-hBN) systems offer new\nroutes in the design of nanoscale electronic devices. Using {\\it ab initio}\ndensity functional theory calculations we investigate the dynamics of zig-zag\nnanoribbons a few interatomic distances wide. Several structures are analyzed,\nnamely pristine graphene, hBN and G-hBN systems. By passivating the nanoribbon\nedges with hydrogen and different halogen atoms, one may tune the electronic\nand mechanical properties, like the band gap energies and the natural\nfrequencies of vibration."
    },
    {
        "anchor": "Resonant electron heating and molecular phonon cooling in single\n  C$_{60}$ junctions: We study heating and heat dissipation of a single \\c60 molecule in the\njunction of a scanning tunneling microscope (STM) by measuring the electron\ncurrent required to thermally decompose the fullerene cage. The power for\ndecomposition varies with electron energy and reflects the molecular resonance\nstructure. When the STM tip contacts the fullerene the molecule can sustain\nmuch larger currents. Transport simulations explain these effects by molecular\nheating due to resonant electron-phonon coupling and molecular cooling by\nvibrational decay into the tip upon contact formation.",
        "positive": "Deformation, lattice instability, and metallization during solid-solid\n  structural transformations under general applied stress tensor: example of Si\n  I -> Si II: Density functional theory (DFT) was employed to study the stress-strain\nbehavior, elastic instabilities, and metallization during a solid-solid phase\ntransformation (PT) between semiconducting Si I (cubic A4) and metallic Si II\n(tetragonal A5 structure) when subjected to a general stress tensor. With\nnormal stresses ($\\sigma_1$, $\\sigma_2$, $\\sigma_3$) acting along $\\left<110\n\\right>$, $\\left<1\\bar{1}0 \\right>$, and $\\left<001\\right>$, respectively,\ndictating the simulation cell, we determine combinations of 6 independent\nstresses that drive a lattice instability for the Si I$\\rightarrow$Si II PT,\nand a semiconductor-metal electronic transition. Metallization precedes the\nstructural PT, hence, a stressed Si I can be a metal. Surprisingly, a\nstress-free Si II is metastable in DFT. Notably, the PT for hydrostatic\npressures is at 75.81 GPa, while under uniaxial stress it is 11.03 GPa (or 3.68\nGPa mean pressure). Our key result: The Si I -> Si II PT is described by a\ncritical value of the modified transformation work, as found with a phase-field\nmethod, and the PT criterion has only two parameters for a general applied\nstress. More generally, our findings are crucial for revealing novel (and more\neconomic) material synthesis routes for new or known high-pressure phases under\ncontrolled and predictable non-hydrostatic loading and plastic deformation."
    },
    {
        "anchor": "The preparation of Zr-deuteride and phase stability studies of the Zr-D\n  system: Deuteride phases in the zirconium-deuterium system in the temperature range\n25-286$\\celsius$ have been studied in-situ by high resolution neutron\ndiffraction. The study primarily focused on observations of $\\delta \\rightarrow\n\\gamma$ transformation at 180$\\celsius$, and the peritectoid reaction $\\alpha +\n\\delta \\leftrightarrow \\gamma$ at 255$\\celsius$ in commercial grade Zr powder\nthat was deuterated to a deuterium/Zr ratio of one to one. A detailed\ndescription of the zirconium deuteride preparation route by high temperature\ngas loading is also described. The lattice parameters of $\\alpha$-Zr,\n$\\delta$-ZrD$_x$ and $\\epsilon$-ZrD$_x$ were determined by whole pattern\ncrystal structure analysis, using Rietveld and Pawley refinements, and are in\ngood agreement with values reported in the literature. The controversial\n$\\gamma$-hydride phase was observed both in-situ and ex-situ in deuterated Zr\npowder after a heat treatment at 286$\\celsius$ and slow cooling.",
        "positive": "Anisotropic Rashba splitting dominated by out-of-plane spin polarization\n  in two-dimensional Janus $XA_{2}Y$ ($A$= Si, Sn, Ge; $X,Y$= Sb, Bi) with\n  surface imperfection: The anisotropic Rashba effect allows for the manipulation of electron spins\nin a more precise and tunable manner since the magnitude of the Rashba\nsplitting and orientation of the spin textures can be simply controlled by\ntuning the direction of the externally applied electric field. Herein, we\npredict the emergence of the anisotropic Rashba effect in the two-dimensional\n(2D) Janus $XA_{2}Y$ constructed from the group IV ($A$= Si, Sn, Ge) and group\nV ($X,Y$ = Sb, Bi) elements having trigonal prismatic structures but lacking\nin-plane mirror symmetry. Due to the lowering point group symmetry of the\ncrystal, the Rashba spin splitting is enforced to becomes anisotropic around\ncertain high symmetry points in the Brillouin zone and preserves the\nout-of-plane spin textures. We illustrate this behavior using density\nfunctional theory calculations supplemented with $\\vec{k}\\cdot\\vec{p}$ analysis\non the Janus SbSi$_{2}$Bi monolayer as a representative example. Specifically,\nwe observed large and anisotropic Rashba splitting with prominence contribution\nof the out-of-plane spin textures in the conduction band minimum around the $M$\npoint and valence band maximum around the $\\Gamma$ point. More importantly, the\nanisotropic spin splitting and out-of-plane spin polarization are sensitively\naffected by surface imperfections, depending on the concentration and\nconfiguration of the $X$ and $Y$ elements in the 2D Janus $XA_{2}Y$ surface.\nOur study offer the possibility to realize the present systems for spintronics\napplications."
    },
    {
        "anchor": "Pressure induced 3D strain in 2D Graphene: Two-dimensional (2D) materials such as graphene offer a variety of\noutstanding properties for a wide range of applications. Their transport\nproperties in particular present a rich field of study. However, the studies of\ntransport properties of graphene under pressure are mostly limited to $\\sim$1\nGPa, largely due to the technical challenges and difficulties of placing\ngraphene inside a diamond anvil cell (DAC) and maintaining good electrical\ncontacts under pressure. We developed a novel technique allowing for direct\nmeasurements of the transport properties of high quality chemical vapor\ndeposition (CVD) monolayer graphene under pressures. Combined Raman\nspectroscopic and direct resistivity measurements on pure monolayer graphene up\nto 40 GPa shows an effective out of plane stiffness of\n$c_{33}$=0.26$\\pm_{.09}^{.11}$ GPa, and observe relatively constant resistances\nwith pressure, suggesting high pressure as a useful technique for producing\nlarge biaxial strains within graphene.",
        "positive": "Comparative Computational Study of the Energetics of Li, Na, and Mg\n  Storage in Amorphous and Crystalline Silicon: To assess the potential of amorphous Si (a-Si) as an anode for Li, Na, and\nMg-ion batteries, the energetics of Li, Na, and Mg atoms in a-Si are computed\nfrom first-principles and compared to those in crystalline Si (c-Si). It is\nshown that Si preamorphization increases the average anode voltage and reduces\nthe volume expansion of the anode during the insertion of the metal atoms.\nAnalysis of computed formation energies of Li, Na, and Mg defects in a-Si and\nc-Si suggests that the energetics of the single atoms into a-Si are\nthermodynamically more favorable. For instance, defect formation energies of\nLi, Na, and Mg defects in a-Si are respectively 0.71, 1.72, and 1.82 eV lower\ncompared to those in c-Si. Moreover, the defect formation energies of Li, Na,\nand Mg defects (vs. vacuum reference states) in a-Si are comparable with the\nmetal cohesive energies and consequently the insertion of the metal atoms might\nbe possible with appropriate control of charging process. This is in contrast\nto c-Si, where the storage of Na and Mg atoms is limited due to high energy\ncost of Na and Mg insertion into c-Si."
    },
    {
        "anchor": "Phase-field model of vapor-liquid-solid nanowire growth: We present a multi-phase-field model to describe quantitatively nanowire\ngrowth by the vapor-liquid-solid (VLS) process. The free-energy functional of\nthis model depends on three non-conserved order parameters that distinguish the\nvapor, liquid, and solid phases. The evolution equations for those order\nparameters describe basic kinetic processes including the rapid\n(quasi-instantaneous) equilibration of the liquid catalyst to a droplet shape\nwith constant mean curvature, the slow incorporation of growth atoms at the\ndroplet surface, and crystallization within the droplet. The standard\nconstraint that the sum of the phase fields equals unity and the conservation\nof the number of catalyst atoms, which relates the catalyst volume to the\nconcentration of growth atoms inside the droplet, are handled via separate\nLagrange multipliers. An analysis of the model is presented that rigorously\nmaps the phase-field equations to a desired set of sharp-interface equations\nfor the evolution of the phase boundaries under the constraint of force-balance\nat three-phase junctions given by the Young-Herring relation that includes\ntorque term related to the anisotropy of the solid-liquid and solid-vapor\ninterface excess free energies. Numerical examples of growth in two dimensions\nare presented. The simulations reproduce many of the salient features of\nnanowire growth observed experimentally, including growth normal to the\nsubstrate with tapering of the side walls, transitions between different growth\norientations, and crawling growth along the substrate.",
        "positive": "Collective electrical response of simulated memristive arrays using\n  SPICE: Self-assembled structures are possible solutions to the problem of increasing\nthe density and connectivity of memristive units in massive arrays. Although\nthey would allow surpassing the limit imposed by the lithographic feature size,\nthe spontaneous formation of highly interconnected networks poses a new\nchallenge: how to characterize and control the obtained assemblies. In view of\na flourishing field of such experimental realizations, this study explores the\ncollective electrical response of simulated memristive units when assembled in\ngeometrically organized and progressively distorted configurations. We show\nthat highly idealized memristive arrays already display a degree of complexity\nthat needs to be taken into account when characterizing self-assemblies to be\ntechnologically exploited. Moreover, the introduction of simple distortions has\na considerable impact on the available resistance states and their evolution\nupon cycling. Considering arrays of a limited size, we also demonstrate that\nthe collective response resembles aspects of the individual model while also\nrevealing its own phenomenology."
    },
    {
        "anchor": "Investigation of the Thermoelectric Properties of ZnV$_{2}$O$_{4}$\n  Compound in High Temperature Region: In the present work, we report the experimental thermopower ($\\alpha$) data\nfor ZnV$_{2}$O$_{4}$ compound in the high temperature range 300-600 K. The\nvalue of $\\alpha$ is found to be $\\sim$184 and $\\sim$126 $\\mu$V/K at $\\sim$300\nand $\\sim$600 K, respectively. The temperature dependent behavior of $\\alpha$\nis almost linear in the measured temperature range. To understand the large and\npositive $\\alpha$ value observed in this compound, we have also investigated\nthe electronic and thermoelectric properties by combining the\n\\textit{ab-initio} electronic structures calculations with Boltzmann transport\ntheory. Within the local spin density approximation plus Hubbard U, the\nanti-ferromagnetic ground state calculation gives an energy gap $\\sim$0.33 eV\nfor U=3.7 eV, which is in accordance with the experimental results. The\neffective mass for holes in the valance band is found nearly four times that of\nelectrons in conduction band. The large effective mass of holes are mainly\nresponsible for the observed positive and large $\\alpha$ value in this\ncompound. There is reasonably good matching between calculated and experimental\n$\\alpha$ data in the temperature range 300-410 K. The power factor calculation\nshows that thermoelectric properties in high temperature region can be enhanced\nby tuning the sample synthesis conditions and suitable doping. The estimated\nvalue of \\textit{figure-of-merit}, ZT, at different absolute temperature\nsuggest that ZnV$_{2}$O$_{4}$ compound can be a good thermoelectric material in\nhigh temperature range.",
        "positive": "Quantum dynamics of crystals of molecular nanomagnets inside a resonant\n  cavity: It is shown that crystals of molecular nanomagnets exhibit enhanced magnetic\nrelaxation when placed inside a resonant cavity. Strong dependence of the\nmagnetization curve on the geometry of the cavity has been observed, providing\nevidence of the coherent microwave radiation by the crystals. A similar\ndependence has been found for a crystal placed between Fabry-Perot\nsuperconducting mirrors. These observations open the possibility of building a\nnanomagnetic microwave laser pumped by the magnetic field."
    },
    {
        "anchor": "Atomic Layer-controlled Nonlinear Terahertz Valleytronics in Dirac\n  Semi-metal and Semiconductor PtSe2: Platinum diselenide (PtSe2) is a promising two-dimensional (2D) material for\nthe terahertz (THz) range as, unlike other transition metal dichalcogenides\n(TMDs), its bandgap can be uniquely tuned from a semiconductor in the\nnear-infrared to a semimetal with the number of atomic layers. This gives the\nmaterial unique THz photonic properties that can be layer-engineered. Here, we\ndemonstrate that a controlled THz nonlinearity - tuned from monolayer to bulk\nPtSe2 - can be realised in wafer size polycrystalline PtSe2 through the\ngeneration of ultrafast photocurrents and the engineering of the bandstructure\nvalleys. This is combined with the PtSe2 layer interaction with the substrate\nfor a broken material centro-symmetry permitting a second order nonlinearity.\nFurther, we show layer-dependent circular dichroism, where the sign of the\nultrafast currents and hence the phase of the emitted THz pulse can be\ncontrolled through the excitation of different bandstructure valleys. In\nparticular, we show that a semimetal has a strong dichroism that is absent in\nthe monolayer and few layer semiconducting limit. The microscopic origins of\nthis TMD bandstructure engineering is highlighted through detailed DFT\nsimulations and show that circular dichroism can be controlled when PtSe2\nbecomes a semimetal and when the K-valleys can be excited. As well as showing\nthat PtSe2 is a promising material for THz generation through layer controlled\noptical nonlinearities, this work opens up new class of circular dichroism\nmaterials beyond the monolayer limit that has been the case of traditional\nTMDs, and impacting a range of domains from THz valleytronics, THz spintronics\nto harmonic generation.",
        "positive": "Estimates of bond length and thermal expansion coefficients from x-ray\n  scattering experimental data using reverse Monte Carlo simulations: The previously discussed anomalous behavior (i.e. negative) of the thermal\nexpansion coefficient obtained from the pair correlation function is examined\nin the context of the nearest-neighbor distance (bond length) distribution. The\nbond length distribution is obtained from a Voronoi tessellation analysis of\nthe atomic structures obtained from both reverse Monte Carlo simulations of\nx-ray scattering data and molecular dynamics simulations. When a robust measure\nof central tendency (mean or median) is used a positive thermal expansion is\nobtained from the temperature-dependent bond length that has the same magnitude\nas that obtained from direct measurements of the volume as a function of\ntemperature. The same is true when larger neighbor distances, as obtained in\nhigher order peaks in the pair distribution function are tracked. This calls\ninto question the recent claim that fragility of metallic liquids is embedded\nin these higher order peaks. It also shows that the previously reported\nanomalous contraction of the bond length arise from tracking the mode, which\ndoes not account for the skewness of the distribution."
    },
    {
        "anchor": "Macroscopic surface charges from microscopic simulations: Attaining accurate average structural properties in a molecular simulation\nshould be considered a prerequisite if one aims to elicit meaningful insights\ninto a system's behavior. For charged surfaces in contact with an electrolyte\nsolution, an obvious example is the density profile of ions along the direction\nnormal to the surface. Here we demonstrate that, in the slab geometry typically\nused in simulations, imposing an electric displacement field $D$ determines the\nintegrated surface charge density of adsorbed ions at charged interfaces. This\nallows us to obtain macroscopic surface charge densities irrespective of the\nslab thickness used in our simulations. We also show that the commonly used\nYeh-Berkowitz method and the 'mirrored slab' geometry both impose vanishing\nintegrated surface charge density. We present results both for relatively\nsimple rocksalt (111) interfaces, and the more complex case of kaolinite's\nbasal faces in contact with aqueous electrolyte solution.",
        "positive": "Theoretical Investigation of Water Formation on Rh and Pt Surfaces: In this report we present a theoretical investigation of the potential-energy\ndiagram for water formation from adsorbed O and H species on Rh(111) and\nPt(111) surfaces. The study is based on accurate first-principles calculations\napplying density-functional theory. Our results are compared to the\npotential-energy diagram for this reaction inferred from experimental data by\nHickman and Schmidt The calculations essentially reproduce the scheme of\nHickman and Schmidt for water formation on Rh(111) with the important\ndifference that the OH molecule is significantly more stable than assumed by\nHickman and Schmidt. On Pt(111) surfaces, however, the calculations predict a\nbarrier to OH formation very similar to that found on Rh(111). In particular,\nthe calculated barrier to OH formation of about 20 kcal/mol seems to contradict\nthe small 2.5 kcal/mol barrier assumed in the Hickman-Schmidt scheme and the\nobserved large rate of water formation on Pt. A possible explanation for the\napparent discrepancy between the large calculated barrier for OH formation on\nPt and the experimentally observed rapid formation of water even at low\ntemperatures is that the active sites for water formation on Pt are at \"defect\"\nsites and not on the ideally flat terraces. A similar conclusion has been\nreached by Verheij and Comsa, who did detailed experimental work on water\nformation on Pt surfaces. Analyzing our results, we develop an explicit picture\nof the interaction processes governing the formation of OH groups. This picture\nrationalizes the calculated weak dependence of OH formation on substrate\nmaterial. An important conclusion from this work is that good catalysts for the\npartial oxidation of hydrocarbons should resist defect formation at their\nsurfaces."
    },
    {
        "anchor": "Localized surface plasmon resonance in graphene nanomesh with Au\n  nanostructures: A hybrid structure of a graphene nanomesh with the gold nanodisks is studied\nto enhance the light absorption by localized surface plasmon resonance. From\nthe reflection spectra of the visible range for graphene nanomesh samples\nwithout and with nanodisks, it is found that the absorption of graphene\nnanomesh structures is greatly enhanced in the presence of gold nanodisks\naround the resonance wavelength. Simulation results based on the\nfinite-difference time-domain method support the experimental observations.\nThis study demonstrates the potential of constructing graphene based\nphotodetectors with a high light absorption efficiency and wavelength\nselectivity.",
        "positive": "Appearance of ferroelectricity in BaO nanowires: We predict that ferroelectric phase can be induced by the strong intrinsic\nsurface stress inevitably present under the curved surface in the high aspect\nratio cylindrical nanoparticles of nonferroelectric binary oxides (BaO, EuO,\nMgO, etc). We calculated the sizes and temperature range of the ferroelectric\nphase in BaO nanowires. The analytical calculations were performed within\nLandau-Ginzburg-Devonshire theory with phenomenological parameters extracted\nfrom the first principle calculations [E. Bousquet et al, Strain-induced\nferroelectricity in simple rocksalt binary oxides. arXiv:0906.4235v1] and\ntabulated experimental data. In accordance with our calculations BaO nanowires\nof radius ~(1-10) nm can be ferroelectric at room temperature (with spontaneous\npolarization values up to 0.5 C/m2) for the typical surface stress coefficients\n~ (10-50) N/m. We hope that our prediction can stimulate both experimental\nstudies of rocksalt binary oxides nanoparticles polar properties as well as the\nfirst principle calculations of their spontaneous dipole moment induced by the\nintrinsic stress under the curved surface."
    },
    {
        "anchor": "Effect of Energetic Disorder on the Open-Circuit Voltage in Organic Bulk\n  Heterojunction Composites: Under open-circuit condition, the current is not extracted and the\nphotogenerated carriers in principle disappear only by recombination. We study\nthe open-circuit voltage $V_{\\rm OC}$ and transient photovoltage under the\neffect of bulk recombination in a medium with energetic disorder by using the\nmultiple trapping (MT) model. The key parameter in the MT model is the\ndispersion parameter $\\alpha$ given by the ratio of thermal energy to the\ncharacteristic energy of trap states. We show that $V_{\\rm OC}$ depends\nlinearly on the logarithm of the light intensity and the slope depends on the\n$\\alpha$ of the MT model. Under the continuous irradiation of light, the\nphotovoltage response to the weak perturbation by a pulsed light obeys\npseudo-first-order decay. The rate as a function of $V_{\\rm OC}$ is independent\nof the dispersion parameter. However, it obeys the power law as a function of\nlight intensity, and the exponent is given by $1/(1+\\alpha)$, which reduces to\n1/2 in the absence of energetic disorder.",
        "positive": "Strain gradient induced electric polarization in alpha-phase\n  polyvinylidene fluoride films under bending conditions: The relationship between the applied elastic strain gradient and the induced\nelectric polarization in the alpha-phase polyvinylidene fluoride (PVDF) films\nunder bending conditions has been investigated. Our experimental studies have\nshown that the flexoelectric polarization is linearly proportional to the\nstrain gradient and the corresponding direct flexoelectric response is strong.\nIt is reasonable to believe that the physical mechanisms behind the\nflexoelectric effects in polymers and solid dielectrics are different."
    },
    {
        "anchor": "Endless Dirac nodal lines in kagome-metal Ni3In2S2: Topological semimetals are a frontier of quantum materials. In multi-band\nelectronic systems, topological band-crossings can form closed curves, known as\nnodal lines. In the presence of spin-orbit coupling and/or symmetry-breaking\noperations, topological nodal lines can break into Dirac/Weyl nodes and give\nrise to novel transport properties, such as the chiral anomaly and giant\nanomalous Hall effect. Recently the time-reversal symmetry-breaking induced\nWeyl fermions are observed in a kagome-metal Co3Sn2S2, triggering interests in\nnodal-line excitations in multiband kagome systems. Here, using\nfirst-principles calculations and symmetry based indicator theories, we find\nsix endless nodal lines along the stacking direction of kagome layers and two\nnodal rings in the kagome plane in nonmagnetic Ni3 In2 S2 . The linear\ndipsersive electronic structure, confirmed by angle-resolved photoemission\nspectroscopy, induces large magnetoresistance up to 2000% at 9 T. Our results\nestablish a diverse topological landscape of multi-band kagome metals.",
        "positive": "Correlation between tunneling magnetoresistance and magnetization in\n  dipolar coupled nanoparticle arrays: The tunneling magnetoresistance (TMR) of a hexagonal array of dipolar coupled\nanisotropic magnetic nanoparticles is studied using a resistor network model\nand a realistic micromagnetic configuration obtained by Monte Carlo\nsimulations. Analysis of the field-dependent TMR and the corresponding\nmagnetization curve shows that dipolar interactions suppress the maximum TMR\neffect, increase or decrease the field-sensitivity depending on the direction\nof applied field and introduce strong dependence of the TMR on the direction of\nthe applied magnetic field. For off-plane magnetic fields, maximum values in\nthe TMR signal are associated with the critical field for irreversible rotation\nof the magnetization. This behavior is more pronounced in strongly interacting\nsystems (magnetically soft), while for weakly interacting systems (magnetically\nhard) the maximum of TMR (Hmax) occurs below the coercive field (Hc), in\ncontrast to the situation for non-interacting nanoparticles or in-plane fields\n(Hmax=Hc). The relation of our simulations to recent TMR measurements in\nself-assembled Co nanoparticle arrays is discussed."
    },
    {
        "anchor": "Cellulose nanocrystals mimicking micron sized fibers to assess the\n  deposition of latex particles on cotton: We report the interactions of cationic latex particles synthesized by\nRAFT/MADIX-mediated emulsion polymerization with anionic cellulose nanocrystals\n(CNCs) and cotton fabrics. Latexes in the size range 200-300 nm with poly(butyl\nacrylate) or poly(2-ethylhexyl acrylate) hydropho-bic cores and hydrophilic\nshell are synthesized. We show that the latex/CNC interaction is me-diated by\nelectrostatics, the interaction being the strongest with the most charged\nparticles. The adsorption process is efficient and does not require any\nfunctionalization step for either cellulose or latex. A major result is the\nobservation by cryogenic transmission electron micros-copy of latexes coated\nwith entangled arrays of CNCs, and for the softer particles a notable\ndeformation of their structure into faceted polyhedra. By labeling the latexes\nwith hydrophobic carbocyanine dyes, their deposition on woven cotton fabrics is\nstudied in situ and quantified by fluorescence microscopy. As with the CNCs,\nthe highest deposition on cotton in the wet and dried states is achieved with\nthe most charged latexes. This demonstrates that CNCs can serve as models to\nadjust the interactions of latex particles with cotton, and thus optimize\nmanufac-turing processes for the development of advanced textiles.",
        "positive": "Route to Achieving Giant Magnetoelectric Coupling in\n  BaTiO$_3$/Sr$_2$CoO$_3$F Perovskite Heterostructures: Polarization induced spin switching of atoms in magnetic materials opens for\npossibilities to design and develop advanced spintronic devices, in particular,\nstorage devices where the magnetic state can be controlled by an electric\nfield. We employ density-functional theory calculations to study the magnetic\nproperties of a perovskite strontium cobalt oxyfluoride Sr$_2$CoO$_3$F (SCOF)\nin a hybrid perovskite heterostructure, where SCOF is sandwiched between two\nferroelectic BaTiO$_3$ (BTO) layers. Our calculations show that the spin state\nof the central Co atom in SCOF can be controlled by altering the polarization\ndirection of the BTO, specifically, to switch from high-spin state to low-spin\nstate by changing the relative orientation of the ferroelectric polarization of\nBTO with respect to SCOF, leading to an unexpected, giant magnetoelectric\ncoupling, $\\alpha_s \\approx 21 \\times 10 ^{-10}$ Gcm$^2$/V."
    },
    {
        "anchor": "Sub-second and ppm-level Optical Sensing of Hydrogen Using Templated\n  Control of Nano-hydride Geometry and Composition: The use of hydrogen as a clean and renewable alternative to fossil fuels\nrequires a suite of flammability mitigating technologies, particularly robust\nsensors for hydrogen leak detection and concentration monitoring. To this end,\nwe have developed a class of lightweight optical hydrogen sensors based on a\nmetasurface of Pd nano-patchy particle arrays, which fulfills the increasing\nrequirements of a safe hydrogen fuel sensing system with no risk of sparking.\nThe structure of the optical sensor is readily nano-engineered to yield\nextraordinarily rapid response to hydrogen gas (<3 s at 1 mbar H$_{2}$) with a\nhigh degree of accuracy (<5%). By incorporating 20% Ag, Au or Co, the sensing\nperformances of the Pd-alloy sensor are significantly enhanced, especially for\nthe Pd$_{80}$Co$_{20}$ sensor whose optical response time at 1 mbar of H$_{2}$\nis just ~0.85 s, while preserving the excellent accuracy (<2.5%), limit of\ndetection (2.5 ppm), and robustness against aging, temperature, and interfering\ngases. The superior performance of our sensor places it among the fastest and\nmost sensitive optical hydrogen sensors.",
        "positive": "Ninety years of X-ray spectroscopy in Italy 1896-1986: Ninety years of X-ray spectroscopy research in Italy, from the X-rays\ndiscovery (1896), and the Fermi group theoretical research (1922-1938) to the\nSynchrotron Radiation research in Frascati from 1963 to 1986 are here\nsummarized showing a coherent scientific evolution which has evolved into the\nactual multidisciplinary research on complex phases of condensed matter with\nsynchrotron radiation."
    },
    {
        "anchor": "On the crystal lattice parameters of graphite-like phases of the B-C\n  system: The structure of graphite-like BCx phases (x = 1, 1.5, 3, 4, 32) has been\nstudied using conventional X-ray diffraction. The results have been obtained,\nwhich unambiguously point to turbostratic (one- dimensionally disordered)\nstructure of all phases under study. The crystal lattice parameters, sizes of\ncoherent scattering domains, and microstrain values have been defined, which\nhave allowed us to find a correlation between the structure and stoichiometry\nof the phases synthesized at the same temperature.",
        "positive": "Empirical Band-Gap Correction for LDA-Derived Atomic Effective\n  Pseudopotentials: Atomic effective pseudopotentials enable atomistic calculations at the level\nof accuracy of density functional theory for semiconductor nanostructures with\nup to fifty thousand atoms. Since they are directly derived from ab-initio\ncalculations performed in the local density approximation (LDA), they inherit\nthe typical underestimated band gaps and effective masses. We propose an\nempirical correction based on the modification of the non-local part of the\npseudopotential and demonstrate good performance for bulk binary materials\n(InP, ZnS, HgTe, GaAs) and quantum dots (InP, CdSe, GaAs) with diameters\nranging from 1.0 nm to 4.45 nm. Additionally, we provide a simple analytic\nexpression to obtain accurate quasiparticle and optical band gaps for InP,\nCdSe, and GaAs QDs, from standard LDA calculation."
    },
    {
        "anchor": "Translational covariance of flexoelectricity at ferroelectric domain\n  walls: Macroscopic descriptions of ferroelectrics have an obvious appeal in terms of\nefficiency and physical intuition. Their predictive power, however, has often\nbeen thwarted by the lack of a systematicp rocedure to extract the relevant\nmaterials parameters from the microscopics. Here we address this limitation by\nestablishing an unambiguous two-way mapping between spatially inhomogeneous\nfields and discrete lattice modes. This yields a natural treatment of gradient\ncouplings in the macroscopic regime via a long-wavelength expansion of the\ncrystal Hamiltonian. Our analysis reveals an inherent arbitrariness in both the\nflexoelectric and polarization gradient coefficients, which we ascribe to a\ntranslational freedom in the definition of the polar distortion pattern.\nRemarkably, such arbitrariness cancels out in all physically measurable\nproperties (relaxed atomic structure and energetics) derived from the model,\npointing to a generalized translational covariance in the continuum description\nof inhomogeneous ferroelectric structures. We demonstrate our claims with\nextensive numerical tests on 180-degree domain walls in common ferroelectric\nperovskites, finding excellent agreement between the continuum model and direct\nfirst-principles calculations.",
        "positive": "Theory and MD simulations of intrinsic localized modes and defect\n  formation in solids: MD simulations of recoil processes following the scattering of X-rays or\nneutrons have been performed in ionic crystals and metals. At small energies\n(<10 eV) the recoil can induce intrinsic localized modes (ILMs) and linear\nlocal modes associated with them. As a rule, the frequencies of such modes are\nlocated in the gaps of the phonon spectrum. However, in metallic Ni, Nb and Fe,\ndue to the renormalization of atomic interactions by free electrons, the\nfrequencies mentioned are found to be positioned above the phonon spectrum. It\nhas been shown that these ILMs are highly mobile and can efficiently transfer a\nconcentrated vibrational energy to large distances along crystallographic\ndirections. If the recoil energy exceeds tens of eVs, vacancies and\ninterstitials can be formed, being strongly dependent on the direction of the\nrecoil momentum. In NaCl-type lattices the recoil in (110) direction can\nproduce a vacancy and a crowdion, while in the case of a recoil in (100) and in\n(111) directions a bi-vacancy and a crowdion can be formed."
    },
    {
        "anchor": "First principles investigations of electronic, magnetic and bonding\n  peculiarities of uranium nitride-fluoride UNF: Based on geometry optimization and magnetic structure investigations within\ndensity functional theory, unique uranium nitride fluoride UNF, isoelectronic\nwith UO2, is shown to present peculiar differentiated physical properties. Such\nspecificities versus the oxide are related with the mixed anionic sublattices\nand the layered-like tetragonal structure characterized by covalent like\n[U2N2]2+motifs interlayered by ionic like [F2]2- ones and illustrated herein\nwith electron localization function graphs. Particularly the ionocovalent\nchemical picture shows, based on overlap population analyses, stronger U-N\nbonding versus N-F and d(U-N) < d(U-F) distances. Based on LDA+U calculations\nthe ground state magnetic structure is insulating antiferromagnet with 2 Bohr\nMagnetons magnetization per magnetic subcell and ~2 eV band gap.",
        "positive": "Thermoelectrics properties of two-dimensional materials with combination\n  of linear and nonlinear band structures: We investigate thermoelectric (TE) properties of two-dimensional materials\npossessing two Dirac bands (a Dirac band) and a nonlinear band within the\nthree-(two-)band model using linearized Boltzmann transport theory and\nrelaxation time approximation. In the three-band model, we find that\ncombinations of Dirac bands with a heavy nonlinear band, either a parabolic or\na pudding-mold band, does not give much difference in their TE performance. The\napparent difference only occurs in the position of the nonlinear band that\nleads to the maximum figure of merit ($ZT$). The optimum $ZT$ of the three-band\nmodel consisting of a nonlinear band is found when the nonlinear band\nintersects the Dirac bands near the Fermi level. By removing the linear\nconduction band, or, in other words, transforming the three-band model to the\ntwo-band model, we find better TE performance in the two-band model than in the\nthree-band model, i.e., in terms of higher $ZT$ values"
    },
    {
        "anchor": "Distinct surface and bulk charge density waves in ultrathin 1T-TaS2: We employ low-frequency Raman spectroscopy to study the nearly commensurate\n(NC) to commensurate (C) charge density wave (CDW) transition in 1T-TaS2\nultrathin flakes protected from oxidation. We identify new modes originating\nfrom C phase CDW phonons that are distinct from those seen in bulk 1T-TaS2. We\nattribute these to CDW modes from the surface layers. By monitoring individual\nmodes with temperature, we find that surfaces undergo a separate,\nlow-hysteresis NC-C phase transition that is decoupled from the transition in\nthe bulk layers. This indicates the activation of a secondary phase nucleation\nprocess in the limit of weak interlayer interaction, which can be understood\nfrom energy considerations.",
        "positive": "Fatigue in disordered media: We obtain the Paris law of fatigue crack propagation in a disordered solid\nusing a fuse network model where the accumulated damage in each resistor\nincreases with time as a power law of the local current amplitude. When a\nresistor reaches its fatigue threshold, it burns irreversibly. Over time, this\ndrives cracks to grow until the system is fractured in two parts. We study the\nrelation between the macroscopic exponent of the crack growth rate -- entering\nthe phenomenological Paris law -- and the microscopic damage-accumulation\nexponent, $\\gamma$, under the influence of disorder. The way the jumps of the\ngrowing crack, $\\Delta a$, and the waiting-time between successive breaks,\n$\\Delta t$, depend on the type of material, via $\\gamma$, are also\ninvestigated. We find that the averages of these quantities, $<\\Delta a>$ and\n$<\\Delta t>/<t_r>$, scale as power laws of the crack length $a$, $<\\Delta a>\n\\propto a^{\\alpha}$ and $<\\Delta t>/<t_r> \\propto a^{-\\beta}$, where $<t_r>$ is\nthe average rupture time. Strikingly, our results show, for small values of\n$\\gamma$, a decrease in the exponent of the Paris law in comparison with the\nhomogeneous case, leading to an increase in the lifetime of breaking materials.\nFor the particular case of $\\gamma=0$, when fatigue is exclusively ruled by\ndisorder, an analytical treatment confirms the results obtained by simulation."
    },
    {
        "anchor": "Ferromagnetism in ZnO co-doped with Mn and N studied by soft x-ray\n  magnetic circular dichroism: We have investigated the electronic structure of ZnO:Mn and ZnO:Mn,N thin\nfilms using x-ray magnetic circular dichroism (XMCD) and\nresonance-photoemission spectroscopy. From the Mn 2$p$$\\rightarrow3d$ XMCD\nresults, it is shown that, while XMCD signals only due to paramagnetic\nMn$^{2+}$ ions were observed in ZnO:Mn, nonmagnetic, paramagnetic and\nferromagnetic Mn$^{2+}$ ions coexist in ZnO:Mn,N. XMCD signals of ZnO:Mn,N\nrevealed that the localized Mn$^{2+}$ ground state and Mn$^{2+}$ state\nhybridized with ligand hole coexisted, implying $p$-$d$ exchange coupling. In\nthe valence-band spectra, spectral weight near the Fermi level was suppressed,\nsuggesting that interaction between magnetic moments in ZnO:Mn,N has localized\nnature.",
        "positive": "A capacitive displacement system for studying the piezoelectric strain\n  and its temperature variation: A capacitive displacement system was constructed to measure the\nelectric-field-induced piezoelectric strain in the simple form of either a bulk\nor thin film. The system can determine an AC displacement of 2 pm precisely by\nusing a lock-in detection, and can measure the large displacement within a\nrange of $\\pm$ 25 $\\mu$m with a sub-nanometer resolution. The system can also\nbe used to measure the variation in strain within a temperature range of 210 -\n450 K, allowing the evaluation of the temperature coefficient of a\npiezoelectric constant and the studies on the effects of a phase transition on\nthe piezoelectric response. Experimental results on quartz, PZT ceramics and\nthin films, and BaTiO$_3$ confirm the capabilities of the developed system."
    },
    {
        "anchor": "Density Functional Theory Study of the Structural Properties of PuH_x,\n  2<=x<=3: Plutonium dihydride and trihydride show strikingly similar crystal structures\nwhen viewed as close-packed Pu planes with ABC and AB stacking, respectively.\nThe similarity serves as a framework for density functional theory (DFT)\ncalculations of PuH2, PuH3, and intermediate compositions. Agreement between\nstructures observed in experiment and in the DFT description of the Pu-H system\nrequires accounting for the strong electronic correlation in the f orbitals,\nachieved here with the addition of a Hubbard parameter U. The hysteresis\nmeasured between hydriding and dehydriding can be attributed to the effect of\nstacking of the close-packed Pu planes on the energy as a function of\nstoichiometry, calculated using the GGA+U approach. Changes in the interstitial\npositions occupied by the H atoms affect the energy by amounts that are\nnegligible compared to room temperature; changes in the magnetic structure lead\nto equally small energy differences.",
        "positive": "Crystal chemistry and ab initio investigations of ultra-hard dense\n  rhombohedral carbon and boron nitride: Rhombohedral dense forms of carbon, rh-C2 (or hexagonal h-C6), and boron\nnitride, rh-BN (or hexagonal h-B3N3), are derived from rhombohedral 3R graphite\nbased on original crystal chemistry scheme backed with full cell geometry\noptimization to minimal energy ground state computations within the quantum\ndensity functional theory. Considering throughout hexagonal settings featuring\nextended lattices, the calculation of the hexagonal set of elastic constants,\nprovide results of large bulk moduli i.e. B0(rh-C2) = 438 GPa close to that of\ndiamond, and B0(rh-BN) = 369 GPa close to that of cubic BN. The hardness\nassessment in the framework of three contemporary models enables both phases to\nbe considered as ultra-hard. From the electronic band structures calculated in\nthe hexagonal Brillouin zones, 3R graphite is a small-gap semiconductor,\noppositely to rh-C2 that is characterized by a large band gap close to 5 eV, as\nwell as the two BN phases."
    },
    {
        "anchor": "Identification of two-dimensional $FeO_2$ termination of hematite\n  $\u03b1-Fe_2O_3(0001)$ surface: Iron oxides are among the most abundant compounds on Earth and have\nconsequently been studied and used extensively in industrial processes. Despite\nthese efforts, concrete understanding of some of their surface phase structures\nhas remained elusive, in particular the oxidized ${\\alpha}-Fe_2O_3(0001)$\nhematite surface. We detail an optimized recipe to produce this phase over the\nentire hematite surface and study the geometrical parameters and composition of\nits complex structure by means of atomically resolved microscopy, electron\ndiffraction and surface-sensitive spectroscopies. We conclude that the oxidized\n${\\alpha}-Fe_2O_3(0001)$ surface is terminated by a two-dimensional iron oxide\nwith structure, lattice parameters, and orientation different from the bulk\nsubstrate. Using total-energy density functional theory for simulation of a\nlarge-scale atomic model, we identify the structure of the surface layer as\nantiferromagnetic, conductive $1T-FeO_2$ attached on half-metal terminated\nbulk. The model succeeds in reproducing the characteristic modulations observed\nin the atomically resolved images and electron diffraction patterns.",
        "positive": "Solid flow drives surface nanopatterning by ion-beam irradiation: Ion Beam Sputtering (IBS) is known to produce surface nanopatterns over\nmacroscopic areas on a wide range of materials. However, in spite of the\ntechnological potential of this route to nanostructuring, the physical process\nby which these surfaces self-organize remains poorly under- stood. We have\nperformed detailed experiments of IBS on Si substrates that validate dynamical\nand morphological predictions from a hydrodynamic description of the\nphenomenon. Our results elucidate flow of a nanoscopically thin and highly\nviscous surface layer, driven by the stress created by the ion-beam, as a\ndescription of the system. This type of slow relaxation is akin to flow of\nmacroscopic solids like glaciers or lead pipes, that is driven by defect\ndynamics."
    },
    {
        "anchor": "Effects of current on vortex and transverse domain walls: By using the spin torque model in ferromagnets, we compare the response of\nvortex and transverse walls to the electrical current. For a defect-free sample\nand a small applied current, the steady state wall mobility is independent of\nthe wall structure. In the presence of defects, the minimum current required to\novercome the wall pinning potential is much smaller for the vortex wall than\nfor the transverse wall. During the wall motion, the vortex wall tends to\ntransform to the transverse wall. We construct a phase diagram for the wall\nmobility and the wall transformation driven by the current.",
        "positive": "Graphene under hydrostatic pressure: In-situ high pressure Raman spectroscopy is used to study monolayer, bilayer\nand few-layer graphene samples supported on silicon in a diamond anvil cell to\n3.5 GPa. The results show that monolayer graphene adheres to the silicon\nsubstrate under compressive stress. A clear trend in this behaviour as a\nfunction of graphene sample thickness is observed. We also study unsupported\ngraphene samples in a diamond anvil cell to 8 GPa, and show that the properties\nof graphene under compression are intrinsically similar to graphite. Our\nresults demonstrate the differing effects of uniaxial and biaxial strain on the\nelectronic bandstructure."
    },
    {
        "anchor": "Thermodynamics of Polydomain Ferroelectric Bilayers and Graded\n  Multilayers: The equilibrium domain structure and its evolution under an electric field in\nferroelectric bilayers and graded multilayers are considered. The equilibrium\nbilayer is self-poled and contains a single-domain and a polydomain (with 180\ndomains) layers. The polarization of a graded multilayer proceeds by movement\nof wedge-like domains as a result of progressive transformation of polydomain\nlayers to a single-domain state. The theory provides the principal explanation\nof peculiarities of dielectric behavior of graded ferroelectric films and can\nbe applied to graded ferromagnetics and ferroelastics.",
        "positive": "Invariants of C$^{1/2}$ in terms of the invariants of C: The three invariants of C$^{1/2}$ are key to expressing this tensor and its\ninverse as a polynomial in C. Simple and symmetric expressions are presented\nconnecting the two sets of invariants $I_1, I_2,I_3$ and $i_1, i_2,i_3 $ of C\nand C$^{1/2}$, respectively. The first result is a bivariate function relating\n$I_1, I_2$ to $i_1, i_2$. The functional form of $i_1$ is the same as that of\n$i_2$ when the roles of the C-invariants are reversed. The second result\nexpresses the invariants using a single call to a single function. The two sets\nof expressions emphasize symmetries in the relations among these four\ninvariants."
    },
    {
        "anchor": "Structural and Magnetic Properties of Fe-Al alloys: an Ab initio Studies: In the framework of density functional theory, the structural and magnetic\nproperties of Fe$_{100-x}$Al$_x$ alloys (${5 \\leq x \\leq 25}$~at.\\%) with the\ndifferent structural order are investigated. Using the Korringa-Kohn-Rostoker\nGreen's function method with a coherent potential approximation, the\nequilibrium lattice parameters, ground-state energy, and shear moduli for\nD0$_3$, B2, and A2 structures are calculated. For all structures, the optimized\nlattice constant increases while the shear modulus demonstrates a decreasing\nbehavior with increasing Al content. The tetragonal magnetostriction constants\nare estimated by the torque method. The A2 and B2 structures provide a positive\ncontribution to the tetragonal magnetostriction. With the help of Monte Carlo\nsimulations of the Heisenberg model, the Curie temperatures are obtained in a\nwide concentration range.",
        "positive": "Nanocomposite NiO:Au hydrogen sensors with high sensitivity and low\n  operating temperature: We present results on the development of nanocomposite NiO:Au thin-film\nhydrogen sensors, which are able to detect hydrogen concentrations as low as 2\nppm in air, operating at low temperatures in the range 125-150C. Thin NiO films\nwere sputter-deposited on oxidized silicon substrates. The structural,\nmorphological, and nanomechanical properties of the films were investigated\nwith respect to post-deposition annealing. Au nanoparticles were added on the\nNiO surface via pulsed laser deposition and the films were tested as hydrogen\nsensors before and after Au deposition. The performance of the NiO films as\nhydrogen sensors improved significantly in the presence of Au nanoparticles on\nthe surface. The detection limit (lowest detectable hydrogen concentration)\ndecreased by two orders of magnitude, while the response time also decreased by\na factor of three."
    },
    {
        "anchor": "Thermoelectricity in ternary rare-earth systems: Crystallographic data, Seebeck coefficient, electrical resistance and thermal\nconductivity are reported for a large number of rare-earth compounds,\nmanifestations of the Kondo effect being discussed. In more detail,\nthermoelectric properties of Yb3Co4Ge13 and Yb3Co4Sn13 compounds and\nYb2CeCo4Ge13 and Yb2.3La0.7Co4Ge13 solid solutions are presented.",
        "positive": "All field emission models are wrong, $\\ldots$ but are any of them\n  useful?: Field emission data are often represented on a Fowler--Nordheim plot but a\nnew empirical equation has been recently proposed to better analyze\nexperiments. Such an equation is based on approximations of the Murphy and Good\nmodel and predicts that a constant parameter $\\kappa$, depending only on the\nwork function of the emitter, can be extracted from the data. We compared this\nempirical equation with simulations of the Murphy and Good model in order to\ndetermine the range of validity of the approximations and the robustness of the\nrelationship between $\\kappa$ and the work function. We found that $\\kappa$ is\nconstant only over a limited range of electric fields and so depends\nsignificantly on the field enhancement factor. This result calls into question\nthe usefulness of the new empirical equation."
    },
    {
        "anchor": "Hall-effect and resistivity measurements in CdTe and ZnTe at high\n  pressure: Electronic structure of impurities in the zincblende phase and the\n  semi-metallic or metallic character of the high-pressure phases: We carried out high-pressure resistivity and Hall-effect measurements in\nsingle crystals of CdTe and ZnTe up to 12 GPa. Slight changes of transport\nparameters in the zincblende phase of CdTe are consitent with the shallow\ncharacter of donor impurities. Drastic changes in all the transport parameters\nof CdTe were found around 4 GPa, i.e. close to the onset of the cinnabar to\nrock-salt transition. In particular, the carrier concentration increases by\nmore than five orders of magnitude. Additionally, an abrupt decrease of the\nresistivity was detected around 10 GPa. These results are discussed in\ncomparison with optical, thermoelectric, and x-ray diffraction experiments. The\nmetallic character of the Cmcm phase of CdTe is confirmed and a semi-metallic\ncharacter is determined for the rock-salt phase. In zincblende ZnTe, the\nincrease of the hole concentration by more than two orders of magnitude is\nproposed to be due to a deep-to-shallow transformation of the acceptor levels.\nBetween 9 and 11 GPa, transport parameters are consistent with the\nsemiconducting character of cinnabar ZnTe. A two orders of magnitude decrease\nof the resistivity and a carrier-type inversion occurs at 11 GPa, in agreement\nwith the onset of the transition to the Cmcm phase of ZnTe. A metallic\ncharacter for this phase is deduced.",
        "positive": "Mechanisms of Ultrafast Charge Separation in a PTB7/Monolayer MoS2 van\n  der Waals Heterojunction: Mixed-dimensional van der Waals heterojunctions comprising polymer and\ntwodimensional (2D) semiconductors have many characteristics of an ideal charge\nseparation interface for optoelectronic and photonic applications. However, the\nphotoelectron dynamics at polymer- 2D semiconductor heterojunction interfaces\nare currently not sufficiently understood to guide the optimization of devices\nfor these applications. This manuscript is a report of a systematic exploration\nof the time-dependent photophysical processes that occur upon photoexcitation\nof a type-II heterojunction between the polymer PTB7 and monolayer MoS2. In\nparticular, photoinduced electron transfer from PTB7 to electronically hot\nstates of MoS2 occurs in less than 250 fs. This process is followed by a slower\n(1-5 ps) exciton diffusion-limited electron transfer from PTB7 to MoS2 with a\nyield of 58%, and a sub-3-ps photoinduced hole transfer from MoS2 to PTB7. The\nequilibrium between excitons and polaron pairs in PTB7 determines the charge\nseparation yield, whereas the 3-4 ns lifetime of photogenerated carriers is\nlimited by MoS2 defects. Overall, this work elucidates the mechanisms of\nultrafast charge carrier dynamics at PTB7-MoS2 interfaces, which will inform\nongoing efforts to exploit polymer-2D semiconductor heterojunctions for\nphotovoltaic and photodetector applications."
    },
    {
        "anchor": "Design of Antiferromagnetic Second-order Band Topology with Rotation\n  Topological Invariants in Two Dimensions: The existence of fractionally quantized topological corner states serves as a\nkey indicator for two-dimensional second-order topological insulators (SOTIs),\nyet has not been experimentally observed in realistic materials. Here, based on\neffective model analysis and symmetry arguments, we propose a strategy for\nachieving SOTI phases with in-gap corner states in two dimensional systems with\nantiferromagnetic (AFM) order. We uncover by a minimum lattice model that the\nband topology originates from the interplay between intrinsic spin-orbital\ncoupling and interlayer AFM exchange interactions. Using first principles\ncalculations, we show that the 2D AFM SOTI phases can be realized in\n(MnBi$_2$Te$_4$)(Bi$_2$Te$_3$)$_{m}$ films. Moreover, we demonstrate that the\nnontrivial corner states are linked to rotation topological invariants under\nthree-fold rotation symmetry $C_3$, resulting in $C_3$-symmetric SOTIs with\ncorner charges fractionally quantized to $\\frac{n}{3} \\lvert e \\rvert $ (mod\n$e$). Due to the great recent achievements in\n(MnBi$_2$Te$_4$)(Bi$_2$Te$_3$)$_{m}$ systems, our results providing reliable\nmaterial candidates for experimentally accessible AFM higher-order band\ntopology would draw intense attentions.",
        "positive": "First-Principles Theory for Schottky Barrier Physics: We develop a first-principles theory for Schottky barrier physics. The\nPoisson equation is solved completely self-consistently with the electrostatic\ncharge density and outside the normal density functional theory (DFT)\nelectronic structure iteration loop, allowing computation of a Schottky barrier\nentirely from DFT involving thousands of atomic layers in the semiconductor.\nThe induced charge in the bulk consists of conduction and valence band charges\nfrom doping and band bending, as well as charge from the evanescent states in\nthe gap of the semiconductor. The Schottky barrier height is determined when\nthe induced charge density and the induced electrostatic potential reach\nself-consistency."
    },
    {
        "anchor": "The mechanism of Li deposition on the Cu substrates in the anode-free Li\n  metal batteries: Due to the rapid growth in the demand for high-energy-density Li batteries\nand insufficient global Li reserves, the anode-free Li metal batteries are\nreceiving increasing attention. Various strategies, such as surface\nmodification and structural design of Cu current collectors, have been proposed\nto stabilize the anode-free Li metal batteries. Unfortunately, the mechanism of\nLi deposition on the Cu surfaces with the different Miller indices is poorly\nunderstood, especially on the atomic scale. Here, a large-scale molecular\ndynamics simulation of Li deposition on the Cu substrates was performed in the\nanode-free Li metal batteries. The results show that the Li layers on the Cu\n(100), Cu (110), and Cu (111) surfaces are closer to the structures of Li\n(110), Li (100), and Li (110) surfaces, respectively. The mechanism was studied\nthrough the surface similarity analysis, potential energy surfaces, and lattice\nfeatures. Finally, a proposal to reduce the fraction of the (110) facet in\ncommercial Cu foils was made to improve the reversibility and stability of Li\nplating/stripping in the anode-free Li metal batteries.",
        "positive": "Annealing effects on the magnetic and magnetotransport properties of\n  iron oxide nanoparticles self-assemblies: In magnetic tunnel junctions based on iron oxide nanoparticles the disorder\nand the oxidation state of the surface spin as well as the nanoparticles\nfunctionalization play a crucial role in the magnetotransport properties. In\nthis work, we report a systematic study of the effects of vacuum annealing on\nthe structural, magnetic and transport properties of self-assembled ~10 nm\nFe3O4 nanoparticles. The high temperature treatment (from 573 to 873 K)\ndecomposes the organic coating into amorphous carbon, reducing the electrical\nresistivity of the assemblies by 4 orders of magnitude. At the same time, the\n3Fe2+/(Fe3++Fe2+) ratio is reduced from 1.11 to 0.13 when the annealing\ntemperature of the sample increases from 573 to 873 K, indicating an important\nsurface oxidation. Although the 2 nm physical gap remains unchanged with the\nthermal treatment, a monotonous decrease of tunnel barrier width was obtained\nfrom the electron transport measurements when the annealing temperature\nincreases, indicating an increment in the number of defects and hot-spots in\nthe gap between the nanoparticles. This is reflected in the reduction of the\nspin dependent tunneling, which reduces the interparticle magnetoresistance.\nThis work shows new insights about influence of the nanoparticle interfacial\ncomposition, as well their the spatial arrangement, on the tunnel transport of\nself-assemblies, and evidence the importance of optimizing the nanostructure\nfabrication for increasing the tunneling current without degrading the spin\npolarized current."
    },
    {
        "anchor": "Reaction pathways of BCl$_3$ for acceptor delta-doping of silicon: BCl$_3$ is a promising candidate for atomic-precision acceptor doping in Si,\nbut optimizing the electrical properties of structures created with this\ntechnique requires a detailed understanding of adsorption and dissociation\npathways for this precursor. Here, we use density functional theory and\nscanning tunneling microscopy (STM) to identify and explore these pathways for\nBCl$_3$ on Si(100) at different annealing temperatures. We demonstrate that\nBCl$_3$ adsorbs selectively without a reaction barrier, and subsequently\ndissociates relatively easily with reaction barriers $\\approx$1 eV. Using this\ndissociation pathway, we parameterize a Kinetic Monte Carlo model to predict B\nincorporation rates as a function of dosing conditions. STM is used to image\nBCl$_{3}$ adsorbates, identifying several surface configurations and tracking\nthe change in their distribution as a function of the annealing temperature,\nmatching predictions of the kinetic model well. This straightforward pathway\nfor atomic-precision acceptor doping helps enable a wide range of applications\nincluding bipolar nanoelectronics, acceptor-based qubits, and superconducting\nSi.",
        "positive": "Proving Nontrivial Topology of Pure Bismuth by Quantum Confinement: The topology of pure Bi is controversial because of its very small ($\\sim$10\nmeV) band gap. Here we perform high-resolution angle-resolved photoelectron\nspectroscopy measurements systematically on 14$-$202 bilayers Bi films. Using\nhigh-quality films, we succeed in observing quantized bulk bands with energy\nseparations down to $\\sim$10 meV. Detailed analyses on the phase shift of the\nconfined wave functions precisely determine the surface and bulk electronic\nstructures, which unambiguously show nontrivial topology. The present results\nnot only prove the fundamental property of Bi but also introduce a capability\nof the quantum-confinement approach."
    },
    {
        "anchor": "Experimental aspects of heat conduction beyond Fourier: Heat conduction experiments are performed in order to identify effects beyond\nFourier. Two experimental setups are discussed. First, a simple experiment by a\nheterogeneous material is investigated from the point of view of generalized\nheat conduction, then the classical laser flash method is analysed.",
        "positive": "In-situ exfoliation method of large-area 2D materials: The success in studying 2D materials inherently relies on producing samples\nof large area, and high quality enough for the experimental conditions. Because\ntheir 2D nature surface sensitive techniques such as photoemission spectroscopy\n, tunneling microscopy and electron diffraction, that work in ultra high vacuum\n(UHV) environment are prime techniques that have been employed with great\nsuccess in unveiling new properties of 2D materials but it requires samples to\nbe free of adsorbates. The technique that most easily and readily yields\n2dmaterials of highest quality is indubitably mechanical exfoliation from bulk\ngrown samples, however as this technique is traditionally done in dedicated\nenvironment, the transfer of these samples into UHV setups requires some form\nof surface cleaning that tempers with the sample quality. In this article, we\nreport on a simple and general method of \\textit{in-situ} mechanical\nexfoliation directly in UHV that yields large-area single-layered films. By\nemploying standard UHV cleaning techniques and by purpusedly exploiting the\nchemical affinity between the substrate and the sample we could yield large\narea exfoliation of transition metal dichalcogenides. Multiple transition metal\ndichalcogenides, both metallic and semiconducting, are exfoliated\n\\textit{in-situ} onto Au and Ag, and Ge. Exfoliated flakes are found to be\nsub-milimeter size with excellent crystallinity and purity, as evidenced by\nangle-resolved photoemission spectroscopy, atomic force microscopy and\nlow-energy electron diffraction. In addition, we demonstrate exfoliation of\nair-sensitive 2D materials and possibility of controlling the substrate-2D\nmaterial twist angle."
    },
    {
        "anchor": "Cluster expansion of multicomponent ionic systems with controlled\n  accuracy: Importance of long-range interactions in heterovalent ionic systems: We have been examining factors determining the accuracy of cluster expansion\n(CE), which is used in combination with many density functional theory (DFT)\ncalculations. With the exception of multicomponent metallic or isovalent ionic\nsystems, the contributions of long-range effective cluster interactions (ECIs)\nto configurational energetics are not negligible, which is ascribed to\nlong-range electrostatic interactions. The truncation of ECIs in such systems\nleads to systematic errors. A typical problem with such errors can be seen in\nMonte Carlo (MC) simulations since simulation supercells composed of a larger\nnumber of atoms than those of the input DFT structures are used. The prediction\nerrors for long-period structures beyond the cell size of the input DFT\nstructures in addition to those for short-period structures within the cell\nsize of the input DFT structures need to be carefully examined to control the\naccuracy of CE. In the present study, we quantitatively discuss the\ncontribution of the truncation of long-range ECIs to the accuracy of CE. Two\ntypes of system, namely, a point-charge spinel lattice and a real MgAl2O4\nspinel crystal, are examined.",
        "positive": "Thin film growth of a topological crystal insulator SnTe on the CdTe\n  (111) surface by molecular beam epitaxy: We report molecular beam epitaxial growth of a SnTe (111) layer on a CdTe\ntemplate, fabricated by depositing it on a GaAs (111)A substrate, instead of\nBaF$_2$ which has been conventionally used as a substrate. By optimizing\ntemperatures for the growth of both SnTe and CdTe layers, we could obtain SnTe\nlayers of the single phase grown only in the (111) orientation and of much\nimproved surface morphology from the viewpoint of the extension and the\nflatness of flat regions, compared to the layers grown on BaF$_2$. In this\noptimal growth condition, we have also achieved a low hole density of the order\nof 10$^{17}$cm$^{-3}$ at 4K, the lowest value ever reported for SnTe thin films\nwithout additional doping. In the magnetoresistance measurement on this\noptimized SnTe layer, we observe characteristic negative magneto-conductance\nwhich is attributed to the weak antilocalization effect of the two-dimensional\ntransport in the topological surface state."
    },
    {
        "anchor": "Raman Spectroscopy of Graphene under Uniaxial Stress: Phonon Softening\n  and Determination of the Crystallographic Orientation: We present a systematic study of the Raman spectra of optical phonons in\ngraphene monolayers under tunable uniaxial tensile stress. Both the G and 2D\nbands exhibit significant red shifts. The G band splits into two distinct\nsub-bands (G+, G-) because of the strain-induced symmetry breaking. Raman\nscattering from the G+ and G- bands shows a distinctive polarization dependence\nthat reflects the angle between the axis of the stress and the underlying\ngraphene crystal axes. Polarized Raman spectroscopy therefore constitutes a\npurely optical method for the determination of the crystallographic orientation\nof graphene.",
        "positive": "Electron-Hole Correlations and Optical Excitonic Gaps in Quantum-Dot\n  Quantum Wells: Tight-Binding Approach: Electron-hole correlation in quantum-dot quantum wells (QDQW's) is\ninvestigated by incorporating Coulomb and exchange interactions into an\nempirical tight-binding model. Sufficient electron and hole single-particle\nstates close to the band edge are included in the configuration to achieve\nconvergence of the first spin-singlet and triplet excitonic energies within a\nfew meV. Coulomb shifts of about 100 meV and exchange splittings of about 1 meV\nare found for CdS/HgS/CdS QDQW's (4.7 nm CdS core diameter, 0.3 nm HgS well\nwidth and 0.3 nm to 1.5 nm CdS clad thickness) which have been characterized\nexperimentally by Weller and co-workers [ D. Schooss, A. Mews, A. Eychmuller,\nH. Weller, Phys. Rev. B, 49, 17072 (1994)]. The optical excitonic gaps\ncalculated for those QDQW's are in good agreement with the experiment."
    },
    {
        "anchor": "Ab initio study of the TiO$_2$ Rutile(110)/Fe interface: Adsorption of Fe on the rutile (110)-surface is investigated by means of {\\it\nab initio} density functional theory calculations. We discuss the deposition of\nsingle Fe atoms, an increasing Fe coverage, as well as the adsorption of small\nFe clusters. It is shown that the different interface structures found in\nexperiment can be understood in terms of the adsorption of the Fe atoms landing\nfirst on the rutile surface. On the one hand, strong interface bonds form if\nsingle Fe atoms are deposited. On the other hand, the Fe-Fe bonds in deposited\nFe clusters lead to a three-dimensional growth mode. Mainly ionic Fe-oxide\nbonds are formed in both cases and the electronic band gap of the surface is\nreduced due to interface states. Besides the structural and electronic\nproperties, we discuss the influence of the interface on the magnetic\nproperties finding stable Fe moments and induced moments within the interface\nwhich leads to a large spin polarization of the Fe atoms at the rutile (110)/Fe\ninterface.",
        "positive": "Violation of the Rule of Parsimony: Mixed Local Moment and Itinerant Fe\n  Magnetism in Fe$_{3}$GeN: Ternary iron nitrides are of considerable interest due to their diverse\nmagnetic properties. We find, based on first principles calculations, that the\nrelatively minor structural distortion from the cubic antiperovskite structure\nin Fe$_3$GeN leads to unusual magnetic behavior. In particular, there is a\nseparation into Fe sites with very different magnetic behaviors, specifically a\nsite with Fe atoms having a stable local moment and a site where the Fe shows\ncharacteristics of much more itinerant behavior. This shows a remarkable\nflexibility of the Fe magnetic behavior in these nitrides and points towards\nthe possibility of systems where minor structural and chemical changes can lead\nto dramatic changes in magnetic properties. The results suggest that,\nanalogously to oxide perovskite materials, modulation of magnetic properties\nvia chemical or strain control of octahedral rotation may be feasible. This may\nthen lead to approaches for tuning magnetism to realize properties of interest,\nfor example tuning magnetic transitions to quantum critical regimes or to\nproximity to metamagnetic transitions of interest for devices."
    },
    {
        "anchor": "Reduced thermal conductivity of TiNiSn/HfNiSn superlattices: Diminution of the thermal conductivity is a crucial aspect in thermoelectric\nresearch. We report a systematic and significant reduction of the cross-plane\nthermal conductivity in a model system consisting of DC sputtered TiNiSn and\nHfNiSn half-Heusler superlattices. The reduction of $\\kappa$ is measured by the\n3$\\omega$ method and originates from phonon scattering at the internal\ninterfaces. Heat transport in the superlattices is calculated based on\nBoltzmann transport theory, including a diffusive mismatch model for the\nphonons at the internal interfaces. Down to superlattice periodicity of 3 nm\nthe phonon spectrum mismatch between the superlattice components quantitatively\nexplains the reduction of $\\kappa$. For very thin individual layers the\ninterface model breaks down and the artificial crystal shows an enhanced\n$\\kappa$. We also present an enhanced ZT value for all investigated\nsuperlattices compared to the single TiNiSn and HfNiSn films.",
        "positive": "Depth-dependent critical behavior in V2H: Using X-ray diffuse scattering, we investigate the critical behavior of an\norder-disorder phase transition in a defective \"skin-layer\" of V2H. In the\nskin-layer, there exist walls of dislocation lines oriented normal to the\nsurface. The density of dislocation lines within a wall decreases continuously\nwith depth. We find that, because of this inhomogeneous distribution of\ndefects, the transition effectively occurs at a depth-dependent local critical\ntemperature. A depth-dependent scaling law is proposed to describe the\ncorresponding critical ordering behavior."
    },
    {
        "anchor": "The electrostatic potential of atomic nanostructures on a metal surface: The discrete and charge-separated nature of matter - electrons and nuclei -\nresults in local electrostatic fields that are ubiquitous in nanoscale\nstructures and are determined by their shape, material, and environment. Such\nfields are relevant in catalysis, nanoelectronics and quantum nanoscience, and\ntheir control will become even more important as the devices in question reach\nfew-nanometres dimensions. Surface-averaging techniques provide only limited\nexperimental access to these potentials at and around individual\nnanostructures. Here, we use scanning quantum dot microscopy to investigate how\nelectric potentials evolve as nanostructures are built up atom by atom. We\nimage the potential over adatoms, chains, and clusters of Ag and Au atoms on\nAg(111) and quantify their surface dipole moments. By focusing on the total\ncharge density, these data establish a new benchmark for ab initio\ncalculations. Indeed, our density functional theory calculations not only show\nan impressive agreement with experiment, but also allow a deeper analysis of\nthe mechanisms behind the dipole formation, their dependence on fundamental\natomic properties and on the atomic configuration of the nanostructures. This\nallows us to formulate an intuitive picture of the basic mechanisms behind\ndipole formation, which enables better design choices for future nanoscale\nsystems such as single atom catalysts.",
        "positive": "Carrier Density Oscillation in photoexcited Semiconductors: The perturbation of a semiconductor from the thermodynamic equilibrium often\nleads to the display of nonlinear dynamics and formation of spatiotemporal\npatterns due to the spontaneous generation of competing processes. Here, we\ndescribe the ultrafast imaging of nonlinear carrier transport in silicon,\nexcited by an intense femtosecond laser pulse. We use scanning ultrafast\nelectron microscopy (SUEM) to show that, at a sufficiently high excitation\nfluence, the transport of photoexcited carriers slows down by turning into an\noscillatory process. We attribute this nonlinear response to the electric\nfield, generated by the spatial separation of these carriers under intrinsic\nand photo-induced fields; we then provide an advection-diffusion model that\nmimics the experimental observation. Our finding provides a direct imaging\nevidence for the electrostatic oscillation of hot carriers in highly excited\nsemiconductors and offers new insights into their spatiotemporal evolution as\nthe equilibrium is recovered."
    },
    {
        "anchor": "Optimizations of GaAs Nanowire Solar Cells: The efficiency of GaAs nanowire solar cells can be significantly improved\nwithout any new processing steps or material requirements. We report coupled\noptoelectronic simulations of a GaAs nanowire (NW) solar cell with vertical\np-i-n junction and high band gap AlInP passivating shell. Our\nfrequency-dependent model facilitates calculation of quantum efficiency for the\nfirst time in NW solar cells. For passivated NWs, we find that short-wavelength\nphotons can be most effectively harnessed by using a thin emitter while\nlong-wavelength photons are best utilized by extending the intrinsic region to\nthe nanowire/substrate interface, and using the substrate as a base. These two\neasily implemented changes, coupled with the increase of NW height to 3.5 um\nwith realistic surface recombination in the presence of a passivation shell,\nresult in a NW solar cell with greater than 19% efficiency.",
        "positive": "Evidence of nickel ions dimerization in NiWO$_4$ and NiWO$_4$-ZnWO$_4$\n  solid solutions probed by EXAFS spectroscopy and reverse Monte Carlo\n  simulations: The existence of exchange-coupled Ni$^{2+}$ ions -- the so-called magnetic\ndimers -- in wolframite-type NiWO$_4$ and Zn$_c$Ni$_{1-c}$WO$_4$ solid\nsolutions with high nickel content was discovered by X-ray absorption\nspectroscopy combined with reverse Monte Carlo (RMC) simulations. Temperature-\n(10--300 K) and composition-dependent x-ray absorption spectra were measured at\nthe Ni K-edge, Zn K-edge, and W L$_3$-edge of microcrystalline NiWO$_4$,\nZn$_c$Ni$_{1-c}$WO$_4$ and ZnWO$_4$. Structural models were obtained from\nsimultaneous analysis of the extended x-ray absorption fine structure (EXAFS)\nspectra at three metal absorption edges using RMC simulations. The obtained\nradial distribution functions for different atomic pairs made it possible to\ntrace in detail the changes in the local environment of metal ions and the\neffect of thermal disorder. Dimerization of Ni$^{2+}$ ions within\nquasi-one-dimensional zigzag chains of [NiO$_6$] octahedra was evidenced in\nNiWO$_4$ in the whole studied temperature range. It manifests itself as the\nsplitting of the Ni-Ni radial distribution function into two separate peaks.\nThe effect is further preserved in solid solutions Zn$_c$Ni$_{1-c}$WO$_4$ for\n$c \\leq 0.6$, which is related to the probability to find two Ni$^{2+}$ ions in\nneighboring positions."
    },
    {
        "anchor": "Direct band gap in gallium sulfide nanostructures: The monolayer Gallium sulfide (GaS) was demonstrated as a promising\ntwo-dimensional semiconductor material with considerable band gaps. The present\nwork investigates the band gap modulation of GaS monolayer under biaxial or\nuniaxial strain by using Density functional theory calculation. We found that\nGaS monolayer shows an indirect band gap that limits its optical applications.\nThe results show that GaS monolayer has a sizable band gap. The uniaxial strain\nshifts band gap from indirect to direct in Gallium monochalcogenides (GaS).\nThis behavior, allowing applications such as electroluminescent devices and\nlaser. The detailed reasons for the band gap modulation are also discussed by\nanalyzing the projected density of states (PDOS). It indicates that due to the\nrole of p$_y$ orbital through uniaxial strain become more significant than\nothers near the Fermi level. The indirect to direct band gap transition happen\nat $\\varepsilon$=-10y$\\%$. Moreover, by investigating the strain energy and\ntransverse response of structures under uniaxial strain, we show that the GaS\nmonolayer has the Poisson's ratio of 0.23 and 0.24 in the zigzag (x) and\narmchair (y) directions, respectively. Thus, we conclude that the isotropic\nnature of mechanical properties under strain.",
        "positive": "Direct observation of intravalley spin relaxation in single-layer WS$_2$: In monolayer Transition Metal Dichalcogenides (TMDs) the valence and\nconduction bands are spin split because of the strong spin-orbit interaction.\nIn tungsten-based TMDs the spin-ordering of the conduction band is such that\nthe so-called dark exciton, consisting of an electron and a hole with opposite\nspin orientation, has lower energy than the A exciton. A possible mechanism\nleading to the transition from bright to dark excitons involves the scattering\nof the electrons from the upper to the lower conduction band state in K. Here\nwe exploit the valley selective optical selection rules and use two-color\nhelicity-resolved pump-probe spectroscopy to directly measure the intravalley\nspin-flip relaxation dynamics of electrons in the conduction band of\nsingle-layer WS$_2$. This process occurs on a sub-ps time scale and it is\nsignificantly dependent on the temperature, indicative of a phonon-assisted\nrelaxation. These experimental results are supported by time-dependent\nab-initio calculations which show that the intra-valley spin-flip scattering\noccurs on significantly longer time scales only exactly at the K point. In a\nrealistic situation the occupation of states away from the minimum of the\nconduction band leads to a dramatic reduction of the scattering time."
    },
    {
        "anchor": "PEG Branched Polymer for Functionalization of Nanomaterials with\n  Ultralong Blood Circulation: Nanomaterials have been actively pursued for biological and medical\napplications in recent years. Here, we report the synthesis of several new\npoly(ethylene glycol) grafted branched-polymers for functionalization of\nvarious nanomaterials including carbon nanotubes, gold nanoparticles (NP) and\ngold nanorods (NRs), affording high aqueous solubility and stability for these\nmaterials. We synthesize different surfactant polymers based upon\npoly-(g-glutamic acid) (gPGA) and poly(maleic anhydride-alt-1-octadecene)\n(PMHC18). We use the abundant free carboxylic acid groups of gPGA for attaching\nlipophilic species such as pyrene or phospholipid, which bind to nanomaterials\nvia robust physisorption. Additionally, the remaining carboxylic acids on gPGA\nor the amine-reactive anhydrides of PMHC18 are then PEGylated, providing\nextended hydrophilic groups, affording polymeric amphiphiles. We show that\nsingle-walled carbon nanotubes (SWNTs), Au NPs and NRs functionalized by the\npolymers exhibit high stability in aqueous solutions at different pHs, at\nelevated temperatures and in serum. Morever, the polymer-coated SWNTs exhibit\nremarkably long blood circulation (t1/2 22.1 h) upon intravenous injection into\nmice, far exceeding the previous record of 5.4 h. The ultra-long blood\ncirculation time suggests greatly delayed clearance of nanomaterials by the\nreticuloendothelial system (RES) of mice, a highly desired property for in vivo\napplications of nanomaterials, including imaging and drug delivery.",
        "positive": "Metastable polymorphic phases in monolayer TaTe2: Polymorphic phases and collective phenomena - such as charge density waves\n(CDWs) - in transition metal dichalcogenides (TMDs) dictate the physical and\nelectronic properties of the material. Most TMDs naturally occur in a single\ngiven phase, but the fine-tuning of growth conditions via methods like\nmolecular beam epitaxy (MBE) allows to unlock otherwise inaccessible\npolymorphic structures. Exploring and understanding the morphological and\nelectronic properties of new phases of TMDs is an essential step to enable\ntheir exploitation in technological applications. Here, we use scanning\ntunneling microscopy to map MBE-grown monolayer TaTe2. We report the first\nobservation of the 1H polymorphic phase, coexisting with the 1T, and\ndemonstrate that their relative coverage can be controlled by adjusting\nsynthesis parameters. Several super-periodic structures, compatible with CDWs,\nare observed to coexist on the 1T phase. Finally, we provide theoretical\ninsight on the delicate balance between Te...Te and Ta-Ta interactions that\ndictates the stability of the different phases. Our findings demonstrate that\nTaTe2 is an ideal platform to investigate competing interactions, and indicate\nthat accurate tuning of growth conditions is key to accessing metastable states\nin TMDs."
    },
    {
        "anchor": "The evolution of precipitate crystal structures in an Al-Mg-Si(-Cu)\n  alloy studied by a combined HAADF-STEM and SPED approach: This work presents a detailed investigation into the effect of a low Cu\naddition (0.01 at.%) on precipitation in an Al-0.80Mg-0.85Si alloy during\nageing. The precipitate crystal structures were assessed by scanning\ntransmission electron microscopy combined with a novel scanning precession\nelectron diffraction approach, which includes machine learning. The combination\nof techniques enabled evaluation of the atomic arrangement within individual\nprecipitates, as well as an improved estimate of precipitate phase fractions at\neach ageing condition, through analysis of a statistically significant number\nof precipitates. Based on the obtained results, the total amount of solute\natoms locked inside precipitates could be approximated. It was shown that even\nwith a Cu content close to impurity levels, the Al-Mg-Si system precipitation\nwas significantly affected with overageing. The principal change was due to a\ngradually increasing phase fraction of the Cu-containing Q'-phase, which\neventually was seen to dominate the precipitate structures. The structural\novertake could be explained based on a continuous formation of the thermally\nstable Q'-phase, with Cu atomic columns incorporating less Cu than what could\npotentially be accommodated.",
        "positive": "Stabilization of highly polar BiFeO$_3$-like structure: a new interface\n  design route for enhanced ferroelectricity in artificial perovskite\n  superlattices: In ABO3 perovskites, oxygen octahedron rotations are common structural\ndistortions that can promote large ferroelectricity in BiFeO3 with an R3c\nstructure [1], but suppress ferroelectricity in CaTiO3 with a Pbnm symmetry\n[2]. For many CaTiO3-like perovskites, the BiFeO3 structure is a metastable\nphase. Here, we report the stabilization of the highly-polar BiFeO3-like phase\nof CaTiO3 in a BaTiO3/CaTiO3 superlattice grown on a SrTiO3 substrate. The\nstabilization is realized by a reconstruction of oxygen octahedron rotations at\nthe interface from the pattern of nonpolar bulk CaTiO3 to a different pattern\nthat is characteristic of a BiFeO3 phase. The reconstruction is interpreted\nthrough a combination of amplitude-contrast sub 0.1nm high-resolution\ntransmission electron microscopy and first-principles theories of the\nstructure, energetics, and polarization of the superlattice and its\nconstituents. We further predict a number of new artificial ferroelectric\nmaterials demonstrating that nonpolar perovskites can be turned into\nferroelectrics via this interface mechanism. Therefore, a large number of\nperovskites with the CaTiO3 structure type, which include many magnetic\nrepresentatives, are now good candidates as novel highly-polar multiferroic\nmaterials [3]."
    },
    {
        "anchor": "Crystal growth and characterization of the pyrochlore Tb$_2$Ti$_2$O$_7$: Terbium titanate (Tb$_2$Ti$_2$O$_7$) is a spin-ice material with remarkable\nmagneto-optical properties. It has a high Verdet constant and is a promising\nsubstrate crystal for the epitaxy of quantum materials with the pyrochlore\nstructure. Large single crystals with adequate quality of Tb$_2$Ti$_2$O$_7$ or\nany pyrochlore are not available so far. Here we report the growth of\nhigh-quality bulk crystals using the Czochralski method to pull crystals from\nthe melt. Prior work using the automated Czochralski method has suffered from\ngrowth instabilities like diameter fluctuation, foot formation and subsequent\nspiraling shortly after the seeding stage. In this study, the volumes of the\ncrystals were strongly increased to several cubic centimeters by means of\nmanual growth control, leading to crystal diameters up to 40 mm and crystal\nlengths up to 10 mm. Rocking curve measurements revealed full width at half\nmaximum values between 28 and 40\" for 222 reflections. The specific heat\ncapacity c$_p$ was measured between room temperature and 1573 K by dynamic\ndifferential scanning calorimetry and shows the typical slow parabolic rise. In\ncontrast, the thermal conductivity \\kappa(T) shows a minimum near 700 K and\nincreases at higher temperature T. Optical spectroscopy was performed at room\ntemperature from the ultraviolet to the near infrared region, and additionally\nin the near infrared region up to 1623 K. The optical transmission properties\nand the crystal color are interpreted to be influenced by partial oxidation of\nTb$^{3+}$ to Tb$^{4+}$.",
        "positive": "Strain-induced magnetization control in an oxide multiferroic\n  heterostructure: Controlling magnetism by using electric fields is a goal of research towards\nnovel spintronic devices and future nano-electronics. For this reason,\nmultiferroic heterostructures attract much interest. Here we provide\nexperimental evidence, and supporting DFT analysis, of a transition in\nLa0.65Sr0.35MnO3 (LSMO) thin film to a stable ferromagnetic phase, that is\ninduced by the structural and strain properties of the ferroelectric BaTiO3\n(BTO) substrate, which can be modified by applying external electric fields.\nX-ray Magnetic Circular Dichroism (XMCD) measurements on Mn L edges with a\nsynchrotron radiation show, in fact two magnetic transitions as a function of\ntemperature that correspond to structural changes of the BTO substrate. We also\nshow that ferromagnetism, absent in the pristine condition at room temperature,\ncan be established by electrically switching the BTO ferroelectric domains in\nthe out-of-plane direction. The present results confirm that electrically\ninduced strain can be exploited to control magnetism in multiferroic oxide\nheterostructures."
    },
    {
        "anchor": "Tuning the conductance topology in solids: The inertia of trapping and detrapping of nonequilibrium charge carriers\naffects the electrochemical and transport properties of both bulk and\nnanoscopic structures in a very peculiar way. An emerging memory response with\na hysteresis in the current-voltage response and its eventual multiple\ncrossing, produced by this universally available ingredient, are signatures of\nthis process. Here, we deliver a microscopic and analytical solution for these\nbehaviors, understood as the modulation of the topology of the current-voltage\nloops. The memory emergence becomes thus a characterization tool for intrinsic\nfeatures that affect the electronic transport of solids such as the nature and\nnumber of trapping sites, intrinsic symmetry constraints, and natural\nrelaxation time scales. This method is also able to reduce the seeming\ncomplexity of frequency-dependent electrochemical impedance and cyclic\nvoltammetry observable for a variety of systems to a combination of simple\nmicroscopic ingredients.",
        "positive": "Molecular Beam Epitaxy of a Half-Heusler Topological Superconductor\n  Candidate YPtBi: The search for topological superconductivity has motivated investigations\ninto materials that combine topological and superconducting properties. The\nhalf-Heusler compound YPtBi appears to be such a material, however experiments\nhave thus far been limited to bulk single crystals, drastically limiting the\nscope of available experiments. This has made it impossible to investigate the\npotential topological nature of the superconductivity in this material.\nExperiments to access details about the superconducting state require\nsophisticated lithographic structures, typically based on thin films. Here we\nreport on the establishment of high crystalline quality epitaxial thin films of\nYPtBi(111), grown using molecular beam epitaxy on Al2O3(0001) substrates. A\nrobust superconducting state is observed, with both critical temperature and\ncritical field consistent with that previously reported for bulk crystals.\nMoreover we find that AlOx capping sufficiently protects the sample surface\nfrom degradation to allow for proper lithography. Our results pave a path\ntowards the development of advanced lithographic structures, that will allow\nthe exploration of the potentially topological nature of superconductivity in\nYPtBi."
    },
    {
        "anchor": "Computational study of structural, elastic, electronic, phonon\n  dispersion relation and thermodynamic properties of orthorhombic CaZrS$_3$\n  for optoelectronic applications: Chalcogenide perovskites offer superior thermal and aqueous stability as well\nas a benign elemental composition compared to organic halide perovskites for\noptoelectronic applications. In this study, the structural, electrical,\nelastic, phonon dispersion, and thermodynamic features of the orthorhombic\nphase of chalcogenide perovskite CaZrS$_3$ (space group Pnma) were examined by\nfirst principles calculations utilizing the plane wave pseudopotentials\n(PW-PPs) in generalized gradient approximations (GGA). The ground state\nproperties such as lattice parameters, unit cell volume, bulk modulus, and its\nderivative were calculated and are in a good agreement with existing findings.\nThe mechanical properties such as bulk modulus, shear modulus, Young's modulus\nand elastic anisotropy were calculated from the obtained elastic constants. The\nratio of bulk modulus to shear modulus confirms that the orthorhombic phase of\nCaZrS$_3$ is a ductile material. The absence of negative frequencies in phonon\ndispersion curve and the phonon density of states give an indication that the\nstructure is dynamically stable. Finally, thermodynamic parameters such as free\nenergy, entropy, and heat capacity were calculated with variation in\ntemperature. The estimated findings follow the same pattern as previous\nefforts.",
        "positive": "Two-dimensional topological semimetal states in monolayers Cu$_2$Ge,\n  Fe$_2$Ge, and Fe$_2$Sn: Recent experimental realizations of the topological semimetal states in\nseveral monolayer systems are very attractive because of their exotic quantum\nphenomena and technological applications. Based on first-principles\ndensity-functional theory calculations including spin-orbit coupling, we here\nexplore the drastically different two-dimensional (2D) topological semimetal\nstates in three monolayers Cu$_2$Ge, Fe$_2$Ge, and Fe$_2$Sn, which are\nisostructural with a combination of the honeycomb Cu or Fe lattice and the\ntriangular Ge or Sn lattice. We find that (i) the nonmagnetic (NM) Cu$_{2}$Ge\nmonolayer having a planar geometry exhibits the massive Dirac nodal lines, (ii)\nthe ferromagentic (FM) Fe$_2$Ge monolayer having a buckled geometry exhibits\nthe massive Weyl points, and (iii) the FM Fe$_2$Sn monolayer having a planar\ngeometry and an out-of-plane magnetic easy axis exhibits the massless Weyl\nnodal lines. It is therefore revealed that mirror symmetry cannot protect the\nfour-fold degenerate Dirac nodal lines in the NM Cu$_{2}$Ge monolayer, but\npreserves the doubly degenerate Weyl nodal lines in the FM Fe$_{2}$Sn\nmonolayer. Our findings demonstrate that the interplay of crystal symmetry,\nmagnetic easy axis, and band topology is of importance for tailoring various 2D\ntopological states in Cu$_2$Ge, Fe$_2$Ge, and Fe$_2$Sn monlayers."
    },
    {
        "anchor": "Layer engineered interlayer excitons: Photoluminescence (PL) from excitons serves as a powerful tool to\ncharacterize the optoelectronic property and band structure of semiconductors,\nespecially for atomically thin 2D transition metal chalcogenide (TMD)\nmaterials. However, PL quenches quickly when the thickness of TMD material\nincreases from monolayer to few-layers, due to the change from direct to\nindirect band transition. Here we show that PL can be recovered by engineering\nmultilayer heterostructures, with the band transition reserved to be direct\ntype. We report emission from layer engineered interlayer excitons from these\nmultilayer heterostructures. Moreover, as desired for valleytronic devices, the\nlifetime, valley polarization, and the valley lifetime of the generated\ninterlayer excitons can all be significantly improved as compared with that in\nthe monolayer-monolayer heterostructure. Our results pave the way for\ncontrolling the properties of interlayer excitons by layer engineering.",
        "positive": "Strain Controlling Catalytic Efficiency of Water Oxidation for\n  Ni1-xFexOOH alloy: A catalyst surface may be exposed to strain due to application of load or\ninterfacing with a substrate with large lattice mismatch. In order to test the\neffect of strain on catalytic efficiency, we use Density Functional Theory +U\n(DFT+U) to model water oxidation on expanded and contracted surfaces of the\nNi1-xFexOOH alloy, one of the best known catalysts for water splitting. We find\nthat a low amount of iron content has a similar effect as of applying\ncompressive strain. Due to high oxidation state of Fe4+ at the active site, the\nFe-O bond is shorter than in pure FeOOH, which is beneficial for extracting\nelectrons from states delocalized on Fe and Ni atoms. At 33% of Fe content the\nefficiency is even better since Fe3+ is at the active site and can easily\nchange oxidation state during the reaction. However, the efficiency drops at\nhigher iron percentages since the surface is unstable and may form FeOOH\naggregates. We find that the best performance is obtained at 33% iron content\nand 5% expansion. Therefore, in addition to changing iron content, strain can\nalso be used as a control handle for improving water splitting catalysis."
    },
    {
        "anchor": "Carrier dynamics in ion-implanted GaAs studied by simulation and\n  observation of terahertz emission: We have studied terahertz (THz) emission from arsenic-ion implanted GaAs both\nexperimentally and using a three-dimensional carrier dynamics simulation. A\nuniform density of vacancies was formed over the optical absorption depth of\nbulk GaAs samples by performing multi-energy implantations of arsenic ions (1\nand 2.4MeV) and subsequent thermal annealing. In a series of THz emission\nexperiments the frequency of peak THz power was found to increase significantly\nfrom 1.4 to 2.2THz when the ion implantation dose was increased from 10^13 to\n10^16 cm-3. We used a semi-classical Monte-Carlo simulation of ultra-fast\ncarrier dynamics to reproduce and explain these results. The effect of the\nion-induced damage was included in the simulation by considering carrier\nscattering at neutral and charged impurities, as well as carrier trapping at\ndefect sites. Higher vacancy concentrations and shorter carrier trapping times\nboth contributed to shorter simulated THz pulses, the latter being more\nimportant over experimentally realistic parameter ranges.",
        "positive": "Pressure dependence of direct optical transitions in ReS2 and ReSe2: We present an experimental and theoretical study of the electronic band\nstructure of ReS2 and ReSe2 at high hydrostatic pressures. The experiments are\nperformed by photoreflectance spectroscopy and are analyzed in terms of ab\ninitio calculations within the density functional theory. Experimental pressure\ncoefficients for the two most dominant excitonic transitions are obtained and\ncompared with those predicted by the calculations. We assign the transitions to\nthe Z k-point of the Brillouin zone and other k-points located away from\nhighsymmetry points. The origin of the pressure coefficients of the measured\ndirect transitions is discussed in terms of orbital analysis of the electronic\nstructure and van der Waals interlayer interaction. The anisotropic optical\nproperties are studied at high pressure by means of polarization-resolved\nphotoreflectance measurements."
    },
    {
        "anchor": "Determination of the micromagnetic parameters in (Ga,Mn)As using domain\n  theory: The magnetic domain structure and magnetic properties of a ferromagnetic\n(Ga,Mn)As epilayer with perpendicular magnetic easy-axis are investigated. We\nshow that, despite strong hysteresis, domain theory at thermodynamical\nequilibrium can be used to determine the micromagnetic parameters. Combining\nmagneto-optical Kerr microscopy, magnetometry and ferromagnetic resonance\nmeasurements, we obtain the characteristic parameter for magnetic domains\n$\\lambda_c$, the domain wall width and specific energy, and the spin stiffness\nconstant as a function of temperature. The nucleation barrier for magnetization\nreversal and the Walker breakdown velocity for field-driven domain wall\npropagation are also estimated.",
        "positive": "Ferroelectric two-level system and phase transition temperature\n  monitoring of $SrTiO_3$ using dielectric resonance modes: The ferroelectric phase transition temperature of a single crystal $SrTiO_3$\ncylindrical puck inserted into a cylindrical copper cavity has been measured\naround $51~K$ using quasi $TE_{m,1,1}$ and quasi $TM_{m,1,1}$ electromagnetic\nmodes. The observed results of such dielectric spectroscopy may be explained by\nimplementing a quasiharmonic approximation of phonons in the incipient\nferroelectric crystal $SrTiO_3$ lattice. The resonant modes act as very\nsensitive probe by implementing measurements of $Q$-factor, transmission or\nfrequency shift when cooling down to low temperatures around a few Kelvin. The\nresonator dielectric losses reveals different crystal unit structure states and\nferroelectric phase transition in continuous cooling. The ferroelectric phase\ntransition initiates a spontaneous polarization $(P_s)$ forming a double-well\npotential in each crystal unit causing a two-level systems, which creates extra\nloss and changes the transmission characteristics and Q-factors of the modes.\nThis process is able to describe resonator properties over a broad range of\nfrequency. Landau's theory of correlation length supports the reported\nobservations as the implication of phonon wave vector $q_c=0$ of central ion in\ncrystal unit symmetry regarding soft-mode."
    },
    {
        "anchor": "Temperature and thickness dependent magnetostatic properties of\n  [Fe/Py]/FeMn/Py multilayers: The magnetic properties of thin-film multilayers [Fe/Py]/FeMn/Py are\ninvestigated as a function of temperature and thickness of the\nantiferromagnetic FeMn spacer using SQUID magnetometry. The observed behavior\ndiffers substantially for the structures with 6-nm and 15-nm FeMn spacers.\nWhile the 15-nm-FeMn structure exhibits exchange pinning of both ferromagnetic\nlayers in the entire measurement temperature interval from 5 to 300 K, the\n6-nm-FeMn structure becomes exchange de-pinned in the vicinity of room\ntemperature. The de-pinned state is characterized by a single hysteresis loop\ncentered around zero field and having enhanced magnetic coercivity. The\nobserved properties are explained in terms of finite-size effects and possibly\nferromagnetic interlayer coupling through the thin antiferromagnetic spacer.",
        "positive": "O$_2$ adsorption trends on small supported PtNi clusters: We present a systematic analysis of molecular oxygen (O$_2$) adsorption\ntrends on bimetallic PtNi clusters and their monometallic counterparts\nsupported on MgO(100), by means of periodic DFT calculations for sizes between\n25 up to 58 atoms. O$_2$ adsorption was studied on a variety of inequivalent\nsites for different structural motifs, such as truncated octahedral (TO),\ncuboctahedral (CO), icosahedral (Ih) and decahedral (Dh) geometries. We found\nthat O$_2$ prefers to bind on top of two metal atoms, parallel to the cluster,\nwith an average chemisorption energy of 1.09 eV (PtNi), 1.07 eV (Pt) and 2.09\neV (Ni), respectively. The largest adsorption energy values are found to be\nalong the edges between two neighbouring (111)/(111) and (111)/(100) facets;\nwhile FCC and HCP sites located on the (111) facets may show a chemisorption\nvalue lower 0.3 eV where often fast O$_2$ dissociation easily occurs. Our\nresults show that, even though it is difficult to disentangle the geometrical\nand electronic effects on the oxygen molecule adsorption, there is a strong\ncorrelation between the calculated general coordination number (GCN) and the\nchemisorp- tion map. Finally, the inclusion of dispersion corrections (DFT-D)\nleads to an overall increase on the calculated adsorption energy values but\nwith a negligible alteration on the general O$_2$ adsorption trends."
    },
    {
        "anchor": "Efficient orbital imaging based on ultrafast momentum microscopy and\n  sparsity-driven phase retrieval: We present energy-resolved photoelectron momentum maps for orbital tomography\nthat have been collected with a novel and efficient time-of-flight momentum\nmicroscopy setup. This setup is combined with a 0.5 MHz table-top femtosecond\nextreme-ultraviolet light source, which enables unprecedented speed in data\ncollection and paves the way towards time-resolved orbital imaging experiments\nin the future. Moreover, we take a significant step forward in the data\nanalysis procedure for orbital imaging, and present a sparsity-driven approach\nto the required phase retrieval problem, which uses only the number of non-zero\npixels in the orbital. Here, no knowledge of the object support is required,\nand the sparsity number can easily be determined from the measured data. Used\nin the relaxed averaged alternating reflections algorithm, this sparsity\nconstraint enables fast and reliable phase retrieval for our experimental as\nwell as noise-free and noisy simulated photoelectron momentum map data.",
        "positive": "Soft Mode Dynamics Above and Below the Burns Temperature in the Relaxor\n  Pb(Mg_1/3Nb_2/3)O_3: We report neutron inelastic scattering measurements of the lowest-energy\ntransverse optic (TO) phonon branch in the relaxor Pb(Mg_1/3Nb_2/3)O_3 from 400\nto 1100 K. Far above the Burns temperature T_d ~ 620 K we observe well-defined\npropagating TO modes at all wave vectors q, and a zone center TO mode that\nsoftens in a manner consistent with that of a ferroelectric soft mode. Below\nT_d the zone center TO mode is overdamped. This damping extends up to, but not\nabove, the waterfall wave vector q_wf, which is a measure of the average size\nof the PNR."
    },
    {
        "anchor": "Effect of Chemical Doping on the Thermoelectric Properties of FeGa3: Thermoelectric properties of the chemically-doped intermetallic narrow-band\nsemiconductor FeGa3 are reported. The parent compound shows semiconductor-like\nbehavior with a small band gap (Eg = 0.2 eV), a carrier density of ~ 10(18)\ncm-3 and, a large n-type Seebeck coefficient (S ~ -400 \\mu V/K) at room\ntemperature. Hall effect measurements indicate that chemical doping\nsignificantly increases the carrier density, resulting in a metallic state,\nwhile the Seebeck coefficient still remains fairly large (~ -150 \\mu V/K). The\nlargest power factor (S2/{\\rho} = 62 \\mu W/m K2) and corresponding figure of\nmerit (ZT = 0.013) at 390 K were observed for Fe0.99Co0.01(Ga0.997Ge0.003)3.",
        "positive": "Landau Theory of Domain Wall Magnetoelectricity: We calculate the exact analytical solution to the domain wall properties in a\nmultiferroic system with two order parameters that are coupled\nbi-quadratically. This is then adapted to the case of a magnetoelectric\nmultiferroic material such as BiFeO3, with a view to examine critically whether\nthe domain walls can account for the enhancement of magnetization reported for\nthin films fo this material, in view of the correlation between increasing\nmagnetization and increasing volume fraction of domain walls as films become\nthinner. The present analysis can be generalized to describe a class of\nmagnetoelectric devices based upon domain walls rather than bulk properties."
    },
    {
        "anchor": "HARES: an efficient method for first-principles electronic structure\n  calculations of complex systems: We discuss our new implementation of the Real-space Electronic Structure\nmethod for studying the atomic and electronic structure of infinite periodic as\nwell as finite systems, based on density functional theory. This improved\nversion which we call HARES (for High-performance-fortran Adaptive grid\nReal-space Electronic Structure) aims at making the method widely applicable\nand efficient, using high performance Fortran on parallel architectures. The\nscaling of various parts of a HARES calculation is analyzed and compared to\nthat of plane-wave based methods. The new developments that lead to enhanced\nperformance, and their parallel implementation, are presented in detail. We\nillustrate the application of HARES to the study of elemental crystalline\nsolids, molecules and complex crystalline materials, such as blue bronze and\nzeolites.",
        "positive": "Coherent Spin Dynamics of Electrons in Two-Dimensional (PEA)$_2$PbI$_4$\n  Perovskites: The versatile potential of lead halide perovskites and two-dimensional\nmaterials is merged in the Ruddlesen-Popper perovskites having outstanding\noptical properties. Here, the coherent spin dynamics in Ruddlesen-Popper\n(PEA)$_2$PbI$_4$ perovskites are investigated by picosecond pump-probe Kerr\nrotation in an external magnetic field. The Larmor spin precession of resident\nelectrons with a spin dephasing time of 190~ps is identified. The longitudinal\nspin relaxation time in weak magnetic fields measured by the spin inertia\nmethod is as long as 25~$\\mu$s. A significant anisotropy of the electron\n$g$-factor with the in-plane value of $+2.45$ and out-of-plane value of $+2.05$\nis found. The exciton out-of-plane $g$-factor is measured to be of $+1.6$ by\nmagneto-reflectivity. This work contributes to the understanding of the\nspin-dependent properties of two-dimensional perovskites and their spin\ndynamics."
    },
    {
        "anchor": "Size-dependent mobility of skyrmions beyond pinning in ferrimagnetic\n  GdCo thin films: Magnetic skyrmions are swirling magnetic textures that can be efficiently\ndriven with spin-orbit torques with a deflected trajectory. However, pinning\nslows skyrmions down and alters their trajectory, which prevents a quantitative\ncomparison to analytical models. Here, we study skyrmions driven by spin-orbit\ntorques at room temperature in ferrimagnetic GdCo thin films, an amorphous\nmaterial with low pinning. Above a sharp current depinning threshold, we\nobserve a clearly linear velocity increase with current that extrapolates to\nzero and a constant deflection angle, reaching high velocities up to 200 m/s.\nThe mobility increases and the depinning threshold current decreases with the\nskyrmion diameter, which we vary using an external magnetic field. An\nanalytical model based on the Thiele equation quantitatively reproduces these\nfindings with a single fitting parameter. This validates the linear flow regime\ndescription and shows, in particular, the important role of skyrmion size in\nits dynamics.",
        "positive": "Diffusion quantum Monte Carlo calculations of SrFeO${_3}$ and\n  LaFeO${_3}$: The equations of state, formation energy and migration energy barrier of the\noxygen vacancy in SrFeO${_3}$ and LaFeO${_3}$ were calculated with the\ndiffusion quantum Monte Carlo (DMC) method. Calculations were also performed\nwith various Density Functional Theory (DFT) approximations for comparison. DMC\nreproduces the measured cohesive energies of these materials with errors below\n0.23(5) eV and the structural properties within 1% of the experimental values.\nThe DMC formation energies of the oxygen vacancy in SrFeO${_3}$ and LaFeO${_3}$\nunder oxygen-rich conditions are 1.3(1) and 6.24(7) eV, respectively. Similar\ncalculations with semi-local DFT approximations for LaFeO$_3$ yielded vacancy\nformation energies 1.5 eV lower. Comparison of charge density evaluated with\nDMC and DFT approximations shows that DFT tends to overdelocalize the electrons\nin defected SrFeO${_3}$ and LaFeO${_3}$. Calculations with DMC and LDA yield\nsimilar vacancy migration energy barriers, indicating that steric/electrostatic\neffects mainly determine migration barriers in these materials."
    },
    {
        "anchor": "Atom Chips: Fabrication and Thermal Properties: Neutral atoms can be trapped and manipulated with surface mounted microscopic\ncurrent carrying and charged structures. We present a lithographic fabrication\nprocess for such atom chips based on evaporated metal films. The size limit of\nthis process is below 1$\\mu$m. At room temperature, thin wires can carry more\nthan 10$^7$A/cm$^2$ current density and voltages of more than 500V. Extensive\ntest measurements for different substrates and metal thicknesses (up to 5\n$\\mu$m) are compared to models for the heating characteristics of the\nmicroscopic wires. Among the materials tested, we find that Si is the best\nsuited substrate for atom chips.",
        "positive": "Layer-dependent Raman spectroscopy of ultrathin Ta$_2$Pd$_3$Te$_5$: Two-dimensional topological insulators (2DTIs) or quantum spin Hall\ninsulators are attracting increasing attention due to their potential\napplications in next-generation spintronic devices. Despite their promising\nprospects, realizable 2DTIs are still limited. Recently, Ta2Pd3Te5, a\nsemiconducting van der Waals material, has shown spectroscopic evidence of\nquantum spin Hall states. However, achieving controlled preparation of few- to\nmonolayer samples, a crucial step in realizing quantum spin Hall devices, has\nnot yet been achieved. In this work, we fabricated few- to monolayer\nTa$_2$Pd$_3$Te$_5$ and performed systematic thickness- and\ntemperature-dependent Raman spectroscopy measurements. Our results demonstrate\nthat Raman spectra can provide valuable information to determine the thickness\nof Ta2Pd3Te5 thin flakes. Moreover, our angle-resolved polarized Raman (ARPR)\nspectroscopy measurements show that the intensities of the Raman peaks are\nstrongly anisotropic due to the quasi-one-dimensional atomic structure,\nproviding a straightforward method to determine its crystalline orientation.\nOur findings may stimulate further efforts to realize quantum devices based on\nfew or monolayer Ta$_2$Pd$_3$Te$_5$."
    },
    {
        "anchor": "Suppression of electron spin relaxation in Mn-doped GaAs: We report a surprisingly long spin relaxation time of electrons in Mn-doped\np-GaAs. The spin relaxation time scales with the optical pumping and increases\nfrom 12 ns in the dark to 160 ns upon saturation. This behavior is associated\nwith the difference in spin relaxation rates of electrons precessing in the\nfluctuating fields of ionized or neutral Mn acceptors, respectively. For the\nlatter the antiferromagnetic exchange interaction between a Mn ion and a bound\nhole results in a partial compensation of these fluctuating fields, leading to\nthe enhanced spin memory.",
        "positive": "Shaping van der Waals nanoribbons via torsional constraints: Scrolls,\n  folds and supercoils: Interplay between structure and function in atomically thin crystalline\nnanoribbons is sensitive to their conformations yet the ability to prescribe\nthem is a formidable challenge. Here, we report a novel paradigm for controlled\nnucleation and growth of scrolled and folded shapes in finite-length\nnanoribbons. All-atom computations on graphene nanoribbons (GNRs) and\nexperiments on macroscale magnetic thin films reveal that decreasing the end\ndistance of torsionally constrained ribbons below their contour length leads to\nformation of these shapes. The energy partitioning between twisted and bent\nshapes is modified in favor of these densely packed soft conformations due to\nthe non-local van Der Waals interactions in these 2D crystals; they subvert the\nformation of supercoils that are seen in their natural counterparts such as DNA\nand filamentous proteins. The conformational phase diagram is in excellent\nagreement with theoretical predictions. The facile route can be readily\nextended for tailoring the soft conformations of crystalline nanoscale ribbons,\nand more general self-interacting filaments"
    },
    {
        "anchor": "Extended defects-enhanced oxygen diffusion in ThO2: Oxygen self-diffusion is key to understanding stoichiometry and defect\nstructures in oxide nuclear fuels. Experimentally, low activation-barrier\noxygen migration was found in ThO$_2$, a candidate nuclear fuel, possibly due\nto short-circuit diffusion mechanisms. Here, we perform extensive molecular\ndynamics simulations to show that various types of extended defects can enhance\noxygen self-diffusion with a much-reduced activation barrier in ThO$_2$. In\nthis work, we consider extended defects including 1D (dislocation), 2D (grain\nboundary), and 3D (void) defects. Due to the distinct characteristics of each\ntype of extended defect, the modulation of oxygen diffusion varies. These\nresults provide a quantitative description of oxygen transport, which is\nsignificantly enhanced within a close distance (nanometer scale) from the\nextended defects. Among all these defects, grain boundary, particularly the\n$\\Sigma 3$ twin boundary with a low formation energy, exhibits the strongest\neffect on increasing oxygen transport.",
        "positive": "The effect of Cu-doping on the magnetic and transport properties of\n  La0.7Sr0.3MnO3: The effects of Cu-doping on the structural, magnetic, and transport\nproperties of La0.7Sr0.3Mn1-xCuxO3 (0 < x < 0.20) have been studied using\nneutron diffraction, magnetization and magnetoresistance (MR) measurements. All\nsamples show the rhombohedral structure with the R3c space-group from 10K to\nroom temperature (RT). Neutron diffraction data suggest that some of the Cu\nions have a Cu3+ state in these compounds. The substitution of Mn by Cu affects\nthe Mn-O bond length and Mn-O-Mn bond angle resulting from the minimization of\nthe distortion of the MnO6 octahedron. Resistivity measurements show that a\nmetal to insulator transition occurs for the x more than 0.15 samples. The x =\n0.15 sample shows the highest MR(_80%), which might result from the\nco-existence of Cu3+/Cu2+ and the dilution effect of Cu-doping on the double\nexchange interaction."
    },
    {
        "anchor": "Clustering of vacancy defects in high-purity semi-insulating SiC: Positron lifetime spectroscopy was used to study native vacancy defects in\nsemi-insulating silicon carbide. The material is shown to contain (i) vacancy\nclusters consisting of 4--5 missing atoms and (ii) Si vacancy related\nnegatively charged defects. The total open volume bound to the clusters\nanticorrelates with the electrical resistivity both in as-grown and annealed\nmaterial. Our results suggest that Si vacancy related complexes compensate\nelectrically the as-grown material, but migrate to increase the size of the\nclusters during annealing, leading to loss of resistivity.",
        "positive": "Intrinsic Dielectric Response in Ferroelectric Nanocrystals: Measurements on 'free-standing' single crystal barium titanate capacitors\nwith thicknesses down to 75nm show a dielectric response typical of large\nsingle crystals rather than conventional thin films. There is a notable absence\nof any broadening or temperature shift of the dielectric peak or loss tangent.\nPeak dielectric constants of ca. 25,000 are obtained, and Curie-Weiss analysis\ndemonstrates 1st order transformation behavior. This is in surprising contrast\nto results on conventionally deposited thin film heterostructures, which show\nlarge dielectric peak broadening and temperature shifts [e.g. C. B. Parker,\nJ-P. Maria and A. I. Kingon, Appl. Phys. Lett., 81, 340 (2002)], as well as an\napparent change in the nature of the paraelectric-ferroelectric transition from\n1st to 2nd order. Our data are compatible with the recent model by Bratkovsky\nand Levanyuk, which attributes dielectric peak broadening to gradient terms\nthat will exist in any thin film capacitor heterostructure, either through\ndefect profiles introduced during growth, or through subtle asymmetry between\ntop and bottom electrodes. The observed recovery of 1st order transformation\nbehavior is consistent with the absence of significant substrate clamping in\nour experiment, as modeled by Pertsev et al. Phys. Rev. Lett., 80, 1988 (1998),\nand illustrates that the 2nd order behaviour seen in conventionally deposited\nthin films cannot be attributed to the effects of reduced dimensionality in the\nsystem, nor to the influence of an intrinsic universal interfacial capacitance\nassociated with the electrode-ferroelectric interface."
    },
    {
        "anchor": "Laser spectroscopy of finite size and covering effects in magnetite\n  nanoparticles: The experiments on the impact of the size of magnetite clusters on various\nmagnetic properties (magnetic moment, Curie temperature, blocking temperature\netc.) have been carried out. The methods of magnetic separation, centrifuging\nof water suspensions of biocompatible iron oxide nanoparticles (NPs) allow\nproducing fractions with diameter of nanoparticles in the range of 4{\\div}22\nnm. The size of NPs are controlled by the methods of dynamic light scattering\n(DLS), transmission electron microscopy (TEM) and atomic force microscopy\n(AFM). For the first time the DLS method is applied in real time to control the\nsize during the process of the separation of the NPs in aqueous suspensions.\nThe changes of the size of NPs cause a shift in the Curie temperature and in\nthe changes in the specific magnetic properties of the iron NPs. The\nexperimental data is interpreted on the basis of Monte Carlo simulations for\nthe classical Heisenberg model with different bulk and surface magnetic\nmoments. It is demonstrated experimentally and by theoretical modeling that\nmagnetic properties of magnetite NPs are determined not only by their sizes,\nbut also by the their surface spin states, while both growing and falling\ndependences of the magnetic moment (per Fe3O4 formula unit) being possible,\ndepending on the number of magnetic atoms in the nanoparticle. Both NPs clean\nand covered with a bioresorbable layer clusters have been investigated.",
        "positive": "Shock Induced Order-disorder Transformation in Ni3Al: The Hugoniot of Ni3Al with L12 structure is calculated with an equation of\nstate (EOS) based on a cluster expansion and variation method from first\nprinciples. It is found that an order-disorder transition occurs at a shock\npressure of 205GPa, corresponding to 3750K in temperature. On the other hand,\nan unexpected high melting temperature about 6955K is obtained at the same\npressure, which is completely different from the case at ambient pressure where\nthe melting point is slightly lower than the order-disorder transition\ntemperature, implying the high pressure phase diagram has its own\ncharacteristics. The present work also demonstrates the configurational\ncontribution is more important than electronic excitations in alloys and\nmineral crystals within a large range of temperature, and an EOS model based on\nCVM is necessary for high pressure metallurgy and theoretical Earth model."
    },
    {
        "anchor": "Pseudopotentials for correlated electron systems: A scheme is developed for creating pseudopotentials for use in\ncorrelated-electron calculations. Pseudopotentials for the light elements H,\nLi, Be, B, C, N, O, and F, are reported, based on data from high-level quantum\nchemical calculations. Results obtained with these correlated electron\npseudopotentials (CEPPs) are compared with data for atomic energy levels and\nthe dissociation energies, molecular geometries and zero-point vibrational\nenergies of small molecules obtained from coupled cluster single double triple\n(CCSD(T)) calculations with large basis sets. The CEPPs give better results in\ncorrelated-electron calculations than Hartree-Fock-based pseudopotentials\navailable in the literature.",
        "positive": "Complete characterization of the macroscopic deformations of periodic\n  unimode metamaterials of rigid bars and pivots: A complete characterization is given of the possible macroscopic deformations\nof periodic nonlinear affine unimode metamaterials constructed from rigid bars\nand pivots. The materials are affine in the sense that their macroscopic\ndeformations can only be affine deformations: on a local level the deformation\nmay vary from cell to cell. Unimode means that macroscopically the material can\nonly deform along a one dimensional trajectory in the six dimensional space of\ninvariants describing the deformation (excluding translations and rotations).\nWe show by explicit construction that any continuous trajectory is realizable\nto an arbitrarily high degree of approximation provided at all points along the\ntrajectory the geometry does not collapse to a lower dimensional one. In\nparticular, we present two and three dimensional dilational materials having an\narbitrarily large flexibility window. These are perfect auxetic materials for\nwhich a dilation is the only easy mode of deformation. They are free to dilate\nto arbitrarily large strain with zero bulk modulus."
    },
    {
        "anchor": "Dynamics in the ordered and disordered phases of barocaloric adamantane: High-entropy order-disorder phase transitions can be used for efficient and\neco-friendly barocaloric solid-state cooling. Here the barocaloric effect is\nreported in an archetypal plastic crystal, adamantane. Adamantane has a\ncolossal isothermally reversible entropy change of 106 J K-1 kg-1 . Extremely\nlow hysteresis means that this can be accessed at pressure differences less\nthan 200 bar. Configurational entropy can only account for about 40% of the\ntotal entropy change; the remainder is due to vibrational effects. Using\nneutron spectroscopy and supercell lattice dynamics calculations, it is found\nthat this vibrational entropy change is mainly caused by softening in the\nhigh-entropy phase of acoustic modes that correspond to molecular rotations. We\nattribute this behaviour to the contrast between an 'interlocked' state in the\nlow-entropy phase and sphere-like behaviour in the high-entropy phase. Although\nadamantane is a simple van der Waals solid with near-spherical molecules, this\napproach can be leveraged for the design of more complex barocaloric molecular\ncrystals. Moreover, this study shows that supercell lattice dynamics\ncalculations can accurately map the effect of orientational disorder on the\nphonon spectrum, paving the way for studying the vibrational entropy, thermal\nconductivity, and other thermodynamic effects in more complex materials.",
        "positive": "Fully self-consistent $GW$ and quasi-particle self-consistent $GW$ for\n  molecules: Two self-consistent schemes involving Hedin's $GW$ approximation are studied\nfor a set of sixteen different atoms and small molecules. We compare results\nfrom the fully self-consistent $GW$ approximation (SC$GW$) and the\nquasi-particle self-consistent $GW$ approximation (QS$GW$) within the same\nnumerical framework. Core and valence electrons are treated on an equal footing\nin all the steps of the calculation. We use basis sets of localized functions\nto handle the space dependence of quantities and spectral functions to deal\nwith their frequency dependence. We compare SC$GW$ and QS$GW$ on a qualitative\nlevel by comparing the computed densities of states (DOS). To judge their\nrelative merit on a quantitative level, we compare their vertical ionization\npotentials (IPs) with those obtained from coupled-cluster calculations CCSD(T).\nOur results are futher compared with \"one-shot\" $G_0W_0$ calculations starting\nfrom Hartree-Fock solutions ($G_0W_0$-HF). Both self-consistent $GW$ approaches\nbehave quite similarly. Averaging over all the studied molecules, both methods\nshow only a small improvement (somewhat larger for SC$GW$) of the calculated\nIPs with respect to $G_0W_0$-HF results. Interestingly, SC$GW$ and QS$GW$\ncalculations tend to deviate in opposite directions with respect to CCSD(T)\nresults. SC$GW$ systematically underestimates the IPs, while QS$GW$ tends to\noverestimate them. $G_0W_0$-HF produces results which are surprisingly close to\nQS$GW$ calculations both for the DOS and for the numerical values of the IPs."
    },
    {
        "anchor": "Ultrahigh-Gain Phototransistors Based on Graphene-MoS2 Heterostructures: Due to its high carrier mobility, broadband absorption, and fast response\ntime, graphene is attractive for optoelectronics and photodetection\napplications. However, the extraction of photoelectrons in conventional\nmetal-graphene junction devices is limited by their small junction area, where\nthe typical photoresponsivity is lower than 0.01 AW-1. On the other hand, the\natomically thin layer of molybdenum disulfide (MoS2) is a two-dimensional (2d)\nnanomaterial with a direct and finite band gap, offering the possibility of\nacting as a 2d light absorber. The optoelectronic properties of the\nheterostructure of these two films is therefore of great interest. The growth\nof large-area graphene using chemical vapour deposition (CVD) has become mature\nnowadays. However, the growth of large-area MoS2 monolayer is still\nchallenging. In this work, we show that a large-area and continuous MoS2\nmonolayer is achievable using a CVD method. Both graphene and MoS2 layers are\ntransferable onto desired substrates, making possible immediate and large-scale\noptoelectronic applications. We demonstrate that a phototransistor based on the\ngraphene/MoS2 heterostructure is able to provide a high photoresponsivity\ngreater than 107 A/W while maintaining its ultrathin and planar structure. Our\nexperiments show that the electron-hole pairs are produced in the MoS2 layer\nafter light absorption and subsequently separated across the layers.\nContradictory to the expectation based on the conventional built-in electric\nfield model for metal-semiconductor contacts, photoelectrons are injected into\nthe graphene layer rather than trapped in MoS2 due to the alignment of the\ngraphene Fermi level with the conduction band of MoS2. The band alignment is\nsensitive to the presence of a perpendicular electric field arising from, for\nexample, Coulomb impurities or an applied gate voltage, resulting in a tuneable\nphotoresponsivity.",
        "positive": "Spontaneous graphitization of ultrathin cubic structures: A\n  computational study: Results based on {\\em ab initio} density functional calculations indicate a\ngeneral graphitization tendency in ultrathin slabs of cubic diamond, boron\nnitride, and many other cubic structures including rocksalt. Whereas such\ncompounds often show an energy preference for cubic rather than layered atomic\narrangements in the bulk, the surface energy of layered systems is commonly\nlower than that of their cubic counterparts. We determine the critical slab\nthickness for a range of systems, below which a spontaneous conversion from a\ncubic to a layered graphitic structure occurs, driven by surface energy\nreduction in surface-dominated structures."
    },
    {
        "anchor": "Coinage-metal capping effects on the spin-reorientations of Co/Ru(0001): Thin films of Co/Ru(0001) are known to exhibit an unusual spin reorientation\ntransition (SRT) coupled to the completion of Co atomic layers for Co\nthicknesses under 4 layers. By means of spin-polarized low-energy electron\nmicroscopy, we follow in real space the magnetization orientation during the\ngrowth of atomically thick capping layers on Co/Ru(0001). Capping with\ncoinage-metal (Cu, Ag, Au) elements modifies the SRT depending on the Co and\noverlayer thickness and on the overlayer material, resulting in an expanded\nrange of structures with high perpendicular magnetic anisotropy. The origin of\nthe SRT can be explained in terms of ab-initio calculations of the\nlayer-resolved contributions to the magnetic anisotropy energy. Besides the\nchanges in the SRT introduced by the capping, a quantitative enhancement of the\nmagnetic anisotropy is identified. A detailed analysis of the interplay between\nstrain and purely electronic effects allows us to identify the conditions that\nlead to a high perpendicular magnetic anisotropy in thin hcp Co films.",
        "positive": "Atomistic behavior of metal surfaces under high electric fields: Combining classical electrodynamics and density functional theory (DFT)\ncalculations, we develop a general and rigorous theoretical framework that\ndescribes the energetics of metal surfaces under high electric fields. We show\nthat the behavior of a surface atom in the presence of an electric field can be\ndescribed by the polarization characteristics of the permanent and\nfield-induced charges in its vicinity. We use DFT calculations for the case of\na W adatom on a W{110} surface to confirm the predictions of our theory and\nquantify its system-specific parameters. Our quantitative predictions for the\ndiffusion of W-on-W{110} under field are in good agreement with experimental\nmeasurements. This work is a crucial step towards developing atomistic\ncomputational models of such systems for long-term simulations."
    },
    {
        "anchor": "Phase diagram of multi-layer ferromagnet system with dipole-dipole\n  interaction: We investigate various magnetic configurations caused by the dipole-dipole\ninteraction (DDI) in the thin-film magnet with the perpendicular anisotropy\nunder the open boundary conditions. Two different approaches are simulated: one\nstarts from a random magnetic configuration and decreases temperatures\nstep-wisely; the other starts from the saturated out-of-plane ferromagnetic\nstate to evaluate its metastability. As typical patterns of magnetic\nconfiguration, five typical configurations are found: an out-of-plane\nferromagnetic, in-plane ferromagnetic, vortex, multi-domain, and canted\nmulti-domain states. Notably, the canted multi-domain forms a concentric\nmagnetic-domain-pattern with an in-plane vortex structure, resulting from the\nopen boundary conditions. Concerning to the coercivity, a comparison of the\nmagnetic configurations in both processes reveals that the out-of-plane\nferromagnetic state exhibits metastability in the multi-domain state, while not\nin the vortex state. We also confirm that the so-called Neel-cap\nmagnetic-domain-wall structure, which is originally discussed in the in-plane\nanisotropy system, appears at the multi-domain state.",
        "positive": "Controlling solid-liquid interfacial energy anisotropy through the\n  isotropic liquid: Although the anisotropy of the solid-liquid interfacial free energy for most\nalloy systems is very small, it plays a crucial role in the growth rate,\nmorphology and crystallographic growth direction of dendrites. Previous work\nposited a dendrite orientation transition via compositional additions. In this\nwork we examine experimentally the change in dendrite growth behaviour in the\nAl-Sm (Samarium) system as a function of solute concentration and study its\ninterfacial properties using molecular dynamics simulations. We observe a\ndendrite growth direction which changes from <100> to <110> as Sm content\nincreases. The observed change in dendrite orientation is consistent with the\nsimulation results for the variation of the interfacial free energy anisotropy\nand thus provides definitive confirmation of conjecture in previous works. In\naddition, our results provide physical insight into the atomic structural\norigin of the concentration dependent anisotropy, and deepens our fundamental\nunderstanding of solid-liquid interfaces in binary alloys."
    },
    {
        "anchor": "The Hubbard model: basic notions and selected applications: The aim of this paper is to present a self contained introduction to the\nHubbard model and some of its applications.The paper consists of two parts: the\nfirst will introduce the basic notions of the Hubbard model starting from the\nmotivation for its development to the formulation of the Hamiltonian,and some\nmethods of calculation within the model. The second part will discuss some\napplications of the model to 1D and 2D systems,based on a combination of the\nauthor's results with those from the literature.",
        "positive": "Electricity at the macroscale and its microscopic origins: I define the fields that describe electrical macrostructure, and their rates\nof change, in terms of the microscopic charge density, electric field, electric\npotential, and their rates of change. To deduce these definitions, I lay some\nfoundations of a general theory of structure homogenization, meaning a theory\nof how any observable macroscopic field is related to spatial averages of its\nmicroscopic counterpart.\n  I apply homogenization theory to the fields that appear in the vacuum theory\nof electromagnetism and deduce that the relationships between macroscopic\nfields are identical in form to the relationships between their microscopic\ncounterparts. Without invoking quantum mechanics, I derive the expressions for\npolarization current established by the Modern Theory of Polarization. I prove\nthat the bulk-average electric potential, or mean inner potential, vanishes in\na macroscopically-uniform charge-neutral material, and I show that when a\ncrystal lattice lacks inversion symmetry, it does not imply the existence of\nmacroscopic $\\vec{E}$ or $\\vec{P}$ fields in the crystal's bulk.\n  I point out that symmetry is scale-dependent. Therefore, if anisotropy of the\nmicrostructure does not manifest as anisotropy of the macrostructure, it cannot\nbe the origin of a macroscopic vector field. The macroscopic charge density is\nisotropic in the bulks of most materials, because it vanishes at every point.\nTherefore, regardless of the microstructure, a macroscopic electric field\ncannot emanate from the bulk. I find that all relationships between observable\nmacroscopic fields can be expressed mathematically without introducing the\npolarization ($\\vec{P}$) and electric displacement ($\\vec{D}$) fields, neither\nof which is observable.\n  ~"
    },
    {
        "anchor": "Upstream modulation in photoreflectance: Photoreflectance is used for the characterisation of semiconductor samples,\nusually by sweeping the monochromatized probe beam within the energy range\ncomprised between the highest value set by the pump beam and the lowest\nabsorption threshold of the sample. There is, however, no fundamental upper\nlimit for the probe beam other than the limited spectral content of the source\nand the responsivity of the detector. As long as the modulation mechanism\nbehind photoreflectance does affect the complete electronic structure of the\nmaterial under study, sweeping the probe beam upstream towards higher energies\nfrom that of the pump source is equally effective in order to probe high energy\ncritical points. This fact, up to now largely overseen, is shown experimentally\nin this work. E1 and E0+{\\Delta}0 critical points of bulk GaAs are\nunambiguously resolved using pump light of lower energy. Upstream modulation\nmay widen further applications of the technique.",
        "positive": "Large, light-induced capacitance enhancement in semiconductor junctions\n  simulated by capacitor-resistor nets: The equivalent circuit simulation of random resistors-capacitors (R-C) net,\nmodified to include large capacitors interfacing between the random R-C bulk\nand the electrode surface, shows an enhancement of 3 orders of magnitude of the\napparent real dielectric constant at low frequencies upon an introduction of\nresistors percolating paths in the bulk. The appearance of the bulk\nR-percolating paths can represent the photo-generated high conductivity state\nof semiconductors bulk, an effect supported by the experimental observation\nthat, in parallel with the photo-enhancement of the real dielectric constant,\nits imaginary part is strongly enhanced as well. The addition of the\nphoto-generated charge carriers strongly enhances bulks electrical\nconductivity, effectively confining the space charge region to the interface\nbetween bulks edge and the electrode. That could be a simple phenomenological\nexplanation for the apparent dielectric constant enhancement upon illumination\nin photocells, not involving elaborate physical models."
    },
    {
        "anchor": "$\u03b2$-As$_2$Te$_3$: Pressure-Induced 3D Dirac Semi-Metal: We report a theoretical \\textit{ab-initio} study of $\\beta$-As$_2$Te$_3$\n($R\\bar{3}m$ symmetry) at hydrostatic pressures up to 12 GPa. We have\nsystematically characterized the vibrational and electronic changes of the\nsystem induced by the pressure variation. The electronic band dispersions\ncalculated at different pressures using \\textit{QS}GW show an insulator-metal\ntransition. At room pressure the system is a semiconductor with small band-gap,\nand the valence and conduction bands present a parabolic conventional\ndispersion. However around 2 GPa the parabolic shape of the bands become linear\nand touch at the Fermi level. This means that this compound undergoes a\npressure-induced topological phase transition to a 3D analog of graphene, known\nas a 3D Dirac semi-metal, with gapless electronic excitations. At increasing\npressures the gap reopens and variation of the character of the electronic\nband-gap from direct to indirect is evidenced. At 7 GPa we observe the\nformation of a negative band-gap character, which persists for pressures up to\n12 GPa. Topological insulating features are evidenced from 2 to 12 GPa with a\nZ$_4$=3 topological index. Moreover by investigating the lattice\nthermal-conductivity at different pressures, we observe an ultra low value of\n$\\kappa_\\textrm{L}$ at 300 K for 0.5 GPa (0.294 and 0.486 Wm$^{-1}$K$^{-1}$ for\nthe $x$-$y$-axis and for the $z$-axis, respectively) which is the result of\nexisting low-frequency optical modes. At 2 GPa $\\kappa_\\textrm{L}$ increases to\n1.170 and 0.669 Wm$^{-1}$K$^{-1}$, for the $x$-$y$-axis and for the $z$-axis,\nrespectively. At 4 GPa the thermal-conductivity values between the two distinct\ncrystallographic axis tend to approximate, with 1.495 and 1.433\nWm$^{-1}$K$^{-1}$, along the $x$-$y$-axis and the $z$-axis, respectively.",
        "positive": "Magnetic anisotropy and lattice dynamics in FeAs studied by M\u00f6ssbauer\n  spectroscopy: Iron mono-arsenide in the powder form has been investigated by transmission\n57Fe Moessbauer spectroscopy in the temperature range 4.2 - 1000 K. Additional\nspectra have been obtained at 20 K and 100 K applying external magnetic field\nof 7 T. It was found that the spin spiral propagating along the c-axis leads to\nthe complex variation of the hyperfine magnetic field amplitude with the spin\norientation varying in the a-b plane. The magnitude of the hyperfine field\npointing in the direction of the local magnetic moment depends on the\norientation of this moment in the a-b plane. Patterns are vastly different for\niron located in the [0 k 0] positions and for iron in the [0 k+1/2 0] positions\nwithin the orthorhombic cell set to the Pnma symmetry. Lattice softens upon\ntransition to the paramagnetic state at 69.2 K primarily in the a-c plane as\nseen by iron atoms. This effect is quite large considering lack of the\nstructural transition. Two previously mentioned iron sites are discernible in\nthe paramagnetic region till 300 K by different electron densities on the iron\nnuclei. The anisotropy of the iron vibrations developed at the transition to\nthe paramagnetic state increases with the temperature in accordance with the\nharmonic approximation, albeit tends to saturation at high temperatures\nindicating gradual onset of the quasi-harmonic conditions. It seems that\nneither hyperfine fields nor magnetic moments are correct order parameters in\nlight of the determined static critical exponents. Sample starts to loose\narsenic at about 1000 K and under vacuum."
    },
    {
        "anchor": "Resonant photon tunneling enhancement of the van der Waals friction: We study the van der Waals friction between two flat metal surfaces in\nrelative motion. For good conductors we find that normal relative motion gives\na much larger friction than for parallel relative motion. The friction may\nincrease by many order of magnitude when the surfaces are covered by\nadsorbates, or can support low-frequency surface plasmons. In this case the\nfriction is determined by resonant photon tunneling between adsorbate\nvibrational modes, or surface plasmon modes.",
        "positive": "Sub-unit cell layer-by-layer growth of Fe3O4, MgO, and Sr2RuO4 thin\n  films: The use of oxide materials in oxide electronics requires their controlled\nepitaxial growth. Recently, it was shown that Reflection High Energy Electron\nDiffraction (RHEED) allows to monitor the growth of oxide thin films even at\nhigh oxygen pressure. Here, we report the sub-unit cell molecular or block\nlayer growth of the oxide materials Sr2RuO4, MgO, and magnetite using Pulsed\nLaser Deposition (PLD) from stoichiometric targets. Whereas for perovskites\nsuch as SrTiO3 or doped LaMnO3 a single RHEED intensity oscillation is found to\ncorrespond to the growth of a single unit cell, in materials where the unit\ncell is composed of several molecular layers or blocks with identical\nstoichiometry, a sub-unit cell molecular or block layer growth is established\nresulting in several RHEED intensity oscillations during the growth of a single\nunit-cell."
    },
    {
        "anchor": "Integrated Digital Inverters Based on Two-dimensional Anisotropic ReS2\n  Field-effect Transistors: Semiconducting two-dimensional (2D) transition metal dichalcogenides (TMDs)\nare emerging as top candidates for post-silicon electronics. While most of 2D\nTMDs exhibit isotropic behavior, lowering the lattice symmetry could induce\nanisotropic properties, which are both scientifically interesting and\npotentially useful. Here, we present atomically thin rhenium disulfide (ReS2)\nflakes with a unique distorted 1T structure, which exhibit in-plane anisotropic\nproperties. We fabricated mono- and few-layer ReS2 field effect transistors\n(FETs), which exhibit competitive performance with large current on/off ratios\n(~107) and low subthreshold swings (100 mV dec-1). The observed anisotropic\nratio along two principle axes reaches 3.1, which is the highest among all\nknown 2D semiconducting materials. Furthermore, we successfully demonstrated an\nintegrated digital inverter with good performance by utilizing two ReS2\nanisotropic FETs, suggesting the promising implementation of large-scale 2D\nlogic circuits. Our results underscore the unique properties of 2D\nsemiconducting materials with low crystal symmetry for future electronic\napplications.",
        "positive": "Mapping the complex evolution of ferroelastic/ferroelectric domain\n  patterns in epitaxially strained PbTiO3 heterostructures: We study the complex ferroelastic/ferroelectric domain structure in the\nprototypical ferroelectric PbTiO3 epitaxially strained on (110)o-oriented\nDyScO3 substrates, using a combination of atomic force microscopy, laboratory\nand synchrotron x-ray diffraction and high resolution scanning transmission\nelectron microscopy. We observe that the anisotropic strain imposed by the\northorhombic substrate creates a large asymmetry in the domain configuration,\nwith domain walls macroscopically aligned along one of the two in-plane\ndirections. We show that the periodicity as a function of film thickness\ndeviates from the Kittel law. As the ferroelectric film thickness increases, we\nfind that the domain configuration evolves from flux-closure to a/c-phase, with\na larger scale arrangement of domains into superdomains."
    },
    {
        "anchor": "Understanding the role of entropy in high entropy oxides: The field of high entropy oxides (HEOs) flips traditional materials science\nparadigms on their head by seeking to understand what properties arise in the\npresence of profound configurational disorder. This disorder, which originates\nfrom multiple elements sharing a single lattice site, can take on a\nkaleidoscopic character due to the vast numbers of possible elemental\ncombinations. High configurational disorder appears to imbue some HEOs with\nfunctional properties that far surpass their non-disordered analogs. While\nexperimental discoveries abound, efforts to characterize the true magnitude of\nthe configurational entropy and understand its role in stabilizing new phases\nand generating superior functional properties have lagged behind. Understanding\nthe role of configurational disorder in existing HEOs is the crucial link to\nunlocking the rational design of new HEOs with targeted properties. In this\nPerspective, we attempt to establish a framework for articulating and beginning\nto address these questions in pursuit of a deeper understanding of the true\nrole of entropy in HEOs.",
        "positive": "Electronic structure induced reconstruction and magnetic ordering at the\n  LaAlO$_3|$SrTiO$_3$ interface: Using local density approximation (LDA) calculations we predict\nGdFeO$_3$-like rotation of TiO$_6$ octahedra at the $n$-type interface between\nLaAlO$_3$ and SrTiO$_3$. The narrowing of the Ti $d$ bandwidth which results\nmeans that for very modest values of $U$, LDA$+U$ calculations predict charge\nand spin ordering at the interface. Recent experimental evidence for magnetic\ninterface ordering may be understood in terms of the close proximity of an\nantiferromagnetic insulating ground state to a ferromagnetic metallic excited\nstate."
    },
    {
        "anchor": "Designing nanostructures for interfacial phonon transport via Bayesian\n  optimization: We demonstrate optimization of thermal conductance across nanostructures by\ndeveloping a method combining atomistic Green's function and Bayesian\noptimization. With an aim to minimize and maximize the interfacial thermal\nconductance (ITC) across Si-Si and Si-Ge interfaces by means of Si/Ge composite\ninterfacial structure, the method identifies the optimal structures from\ncalculations of only a few percent of the entire candidates (over 60,000\nstructures). The obtained optimal interfacial structures are non-intuitive and\nimpacting: the minimum-ITC structure is an aperiodic superlattice that realizes\n50% reduction from the best periodic superlattice. The physical mechanism of\nthe minimum ITC can be understood in terms of crossover of the two effects on\nphonon transport: as the layer thickness in superlattice increases, the impact\nof Fabry-P\\'erot interference increases, and the rate of reflection at the\nlayer-interfaces decreases. Aperiodic superlattice with spatial variation in\nthe layer thickness has a degree of freedom to realize optimal balance between\nthe above two competing mechanism. Furthermore, aperiodicity breaks the\nconstructive phonon interference between the interfaces inhibiting the coherent\nphonon transport. The present work shows the effectiveness and advantage of\nmaterial informatics in designing nanostructures to control heat conduction,\nwhich can be extended to other interfacial structures.",
        "positive": "Determining the Optimal Phase-Change Material via High-Throughput\n  Calculations: The discovery and optimization of phase-change and shape memory alloys remain\na tedious and expensive process. Here a simple computational method is proposed\nto determine the ideal phase-change material for a given alloy composed of\nthree elements. Using first-principles calculations, within a high-throughput\nframework, the ideal composition of a phase-change material between any two\nassumed phases can be determined. This ideal composition minimizes the\ninterface strain during the structural transformation. Then one can target this\nideal composition experimentally to produce compounds with low mechanical\nfailure rates for a potentially wide variety of applications. Here we will\nprovide evidence of the effectiveness of our calculations for a well-known\nphase-change material in which we predict the ideal composition and compare it\nto experimental results."
    },
    {
        "anchor": "Direct observation of ultrafast thermal and non-thermal lattice\n  deformation of polycrystalline Aluminum film: The dynamics of thermal and non-thermal lattice deformation of nanometer\nthick polycrystalline aluminum film has been studied by means of femtosecond\n(fs) time-resolved electron diffraction. We utilized two different pump\nwavelengths: 800 nm, the fundamental of Ti: sapphire laser and 1250 nm\ngenerated by a home-made optical parametric amplifier(OPA). Our data show that,\nalthough coherent phonons were generated under both conditions, the diffraction\nintensity decayed with the characteristic time of 0.9+/-0.3 ps and 1.7+/-0.3 ps\nunder 800 nm and 1250 nm excitation, respectively. Because the 800 nm laser\nexcitation corresponds to the strong interband transition of aluminum due to\nthe 1.55 eV parallel band structure, our experimental data indicate the\npresence of non-thermal lattice deformation under 800 nm excitation, which\noccurs on a time-scale that is shorter than the thermal processes dominated by\nelectron-phonon coupling under 1250 nm excitation.",
        "positive": "Comment on \"Unconventional enhancement of ferromagnetic interactions in\n  Cd-doped GdFe2Zn20 single crystals studied by ESR and 57Fe Mossbauer\n  spectroscopies\": In the recent publication, Phys. Rev. B 102, 144420 (2020), Cabrera-Baez et\nal. present a study of the effects of Cd-substitution for Zn in the\nferromagnetic compound GdFe2Zn20. As part of this paper, they claim that for\nGdFe2Zn18.6Cd1.4 the effective moment of Gd is reduced by 25% and the saturated\nmoment of Gd is reduced by over 40%. We regrew representative members of the\nGdFe2Zn(20-x)Cdx series and did not find any such reductions. In addition, we\nmeasured several crystals from the growth batch that was used by Cabrera-Baez\net al. and did not see such reductions. Although there is a modest increase in\nTC with Cd substitution, there is no significant change in the Gd effective\nmoment or the saturated moment associated with the low temperature\nferromagnetic state."
    },
    {
        "anchor": "Mesoscopic mechanism of the domain wall interaction with elastic defects\n  in ferroelectrics: The role of elastic defects on the kinetics of 180-degree uncharged\nferroelectric domain wall motion is explored using continuum time-dependent LGD\nequation with elastic dipole coupling. In one dimensional case, ripples, steps\nand oscillations of the domain wall velocity appear due to the wall-defect\ninteractions. While the defects do not affect the limiting-wall velocity vs.\nfield dependence, they result in the minimal threshold field required to\nactivate the wall motions. The analytical expressions for the threshold field\nare derived and the latter is shown to be much smaller than the thermodynamic\ncoercive field. The threshold field is linearly proportional to the\nconcentration of defects and non-monotonically depends on the average distance\nbetween them. The obtained results provide the insight into the mesoscopic\nmechanism of the domain wall pinning by elastic defects in ferroelectrics.",
        "positive": "Ductile and brittle crack-tip response in equimolar refractory\n  high-entropy alloys: Understanding the strengthening and deformation mechanisms in refractory\nhigh-entropy alloys (HEAs), proposed as new high-temperature material, is\nrequired for improving their typically insufficient room-temperature ductility.\nHere, density-functional theory simulations and a continuum mechanics analysis\nwere conducted to systematically investigate the competition between cleavage\ndecohesion and dislocation emission from a crack tip in the body-centered cubic\nrefractory HEAs HfNbTiZr, MoNbTaVW, MoNbTaW, MoNbTiV, and NbTiVZr. This\ncrack-tip competition is evaluated for tensile loading and a totality of 15\ncrack configurations and slip systems. Our results predict that dislocation\nplasticity at the crack tip is generally unfavorable -- although the\ncompetition is close for some crack orientations, suggesting intrinsic\nbrittleness and low crack-tip fracture toughness in these five HEAs at zero\ntemperature. Fluctuations in local alloy composition, investigated for\nHfNbTiZr, can locally reduce the resistance to dislocation emission for a slip\nsystem relative to the configuration average of that slip system, but do not\nchange the dominant crack-tip response. In the case of single-crystal MoNbTaW,\nwhere an experimental, room-temperature fracture-toughness value is available\nfor a crack on a \\{100\\} plane, theoretical and experimental results agree\nfavorably. Factors that may limit the agreement are discussed. We survey the\neffect of material anisotropy on preferred crack tip orientations, which are\nfound to be alloy specific. Mixed-mode loadings are found to shift the\ncompetition in favor of cleavage or dislocation nucleation, depending on crack\nconfiguration and amplified by the effect of material anisotropy on crack tip\nstresses."
    },
    {
        "anchor": "Emergent exotic chirality dependent dielectricity in magnetic twisted\n  bilayer system: Twisted van der Waals bilayers provide an ideal platform to study the\nelectron correlation in solids. Of particular interest is the 30 degree twisted\nbilayer honeycomb lattice system, which possesses an incommensurate Moire\npattern and uncommon electronic behaviors may appear due to the absence of\nphase coherence. Such system is extremely sensitive to further twist and many\nintriguing phenomena will occur. In this work, we show that due to the twist\ninduced spatial inhomogeneity of interlayer coupling, there emerges an U(1)\ngauge field in magnetic transition-metal dichalcogenides (TMD) bilayers.\nInterestingly, for further twist near 30 degree, the induced gauge field could\nform a chirality dependent real-space skyrmion pattern, or magnetic charge.\nMoreover, such twist also induces the topology dependent electronic\npolarization of the bilayer system through the nonzero flux of the real-space\nBerry curvature. Further analysis proves that the antiferromagnetically coupled\ntwisted bilayer system is indeed also antiferroelectric! When an external\nelectric field is applied to break the potential balance between layers, there\nwill emerge novel magnetoelectric coupling and exotic chirality dependent\ndielectricity. Such findings not only enrich our understanding on Moire\nsystems, but also open an appealing route toward functional 2D materials design\nfor electronic, optical and even energy storage devices.",
        "positive": "Thermal Diffusivities of Functionalized Pentacene Semiconductors: We have measured the interlayer and in-plane (needle axis) thermal\ndiffusivities of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-Pn). The\nneedle axis value is comparable to the phonon thermal conductivities of\nquasi-one dimensional organic metals with excellent pi-orbital overlap, and its\nvalue suggests that a significant fraction of heat is carried by optical\nphonons. Furthermore, the interlayer (c-axis) thermal diffusivity is at least\nan order of magnitude larger, and this unusual anisotropy implies very strong\ndispersion of optical modes in the interlayer direction, presumably due to\ninteractions between the silyl-containing side groups. Similar values for both\nin-plane and interlayer diffusivities have been observed for several other\nfunctionalized pentacene semiconductors with related structures."
    },
    {
        "anchor": "Electric double-layer transistor using layered iron selenide Mott\n  insulator TlFe1.6Se2: A1-xFe2-ySe2 (A = K, Cs, Rb, Tl) are recently discovered iron-based\nsuperconductors with critical temperatures (Tc) ranging up to 32 K. Their\nparent phases have unique properties when compared with other iron-based\nsuperconductors; e.g., their crystal structures include ordered Fe vacancies,\ntheir normal states are antiferromagnetic (AFM) insulating phases, and they\nhave extremely high N\\'eel transition temperatures. However, control of carrier\ndoping into the parent AFM insulators has been difficult due to their intrinsic\nphase separation. Here, we fabricated an Fe-vacancy-ordered TlFe1.6Se2\ninsulating epitaxial film with an atomically flat surface and examined its\nelectrostatic carrier doping using an electric double-layer transistor (EDLT)\nstructure with an ionic liquid gate. The positive gate voltage gave conductance\nmodulation of three orders of magnitude at 25 K, and further induced and\nmanipulated a phase transition; i.e., delocalized carrier generation by\nelectrostatic doping is the origin of the phase transition. This is the first\ndemonstration, to the authors' knowledge, of an EDLT using a Mott insulator\niron-selenide channel and opens a way to explore high-Tc superconductivity in\niron-based layered materials, where carrier doping by conventional chemical\nmeans is difficult.",
        "positive": "Accelerated Discovery of Molten Salt Corrosion-resistant Alloy by\n  High-throughput Experimental and Modeling Methods Coupled to Data Analytics: Insufficient availability of molten salt corrosion-resistant alloys severely\nlimits the fruition of a variety of promising molten salt technologies that\ncould otherwise have significant societal impacts. To accelerate alloy\ndevelopment for molten salt applications and develop fundamental understanding\nof corrosion in these environments, here we present an integrated approach\nusing a set of high-throughput alloy synthesis, corrosion testing, and modeling\ncoupled with automated characterization and machine learning. By using this\napproach, a broad range of Cr-Fe-Mn-Ni alloys were evaluated for their\ncorrosion resistances in molten salt simultaneously demonstrating that\ncorrosion-resistant alloy development can be accelerated by thousands of times.\nBased on the obtained results, we unveiled a sacrificial mechanism in the\ncorrosion of Cr-Fe-Mn-Ni alloys in molten salts which can be applied to protect\nthe less unstable elements in the alloy from being depleted, and provided new\ninsights on the design of high-temperature molten salt corrosion-resistant\nalloys."
    },
    {
        "anchor": "Interface bonding of a ferromagnetic/semiconductor junction : a\n  photoemission study of Fe/ZnSe(001): We have probed the interface of a ferromagnetic/semiconductor (FM/SC)\nheterojunction by a combined high resolution photoemission spectroscopy and\nx-ray photoelectron diffraction study. Fe/ZnSe(001) is considered as an example\nof a very low reactivity interface system and it expected to constitute large\nTunnel Magnetoresistance devices. We focus on the interface atomic environment,\non the microscopic processes of the interface formation and on the iron\nvalence-band. We show that the Fe contact with ZnSe induces a chemical\nconversion of the ZnSe outermost atomic layers. The main driving force that\ninduces this rearrangement is the requirement for a stable Fe-Se bonding at the\ninterface and a Se monolayer that floats at the Fe growth front. The released\nZn atoms are incorporated in substitution in the Fe lattice position. This\nformation process is independent of the ZnSe surface termination (Zn or Se).\nThe Fe valence-band evolution indicates that the d-states at the Fermi level\nshow up even at submonolayer Fe coverage but that the Fe bulk character is only\nrecovered above 10 monolayers. Indeed, the Fe &#61508;1-band states,\ntheoretically predicted to dominate the tunneling conductance of Fe/ZnSe/Fe\njunctions, are strongly modified at the FM/SC interface.",
        "positive": "Massless Fermions in multilayer graphitic systems with misoriented\n  layers: We examine how the misorientation of a few stacked graphene layers affects\nthe electronic structure of carbon nanosystems. We present {\\it ab initio}\ncalculations on bi- and trilayer systems to demonstrate that the massless\nFermion behavior typical of single layered graphene is also found in\nincommensurate multilayered graphitic systems. We also investigate the\nconsequences of this property on experimental fingerprints, such as Raman\nspectroscopy and scanning tunneling microscopy (STM). Our simulations reveal\nthat STM images of turbostratic few layer graphite are sensitive to the layer\narrangement. We also predict that resonant raman signal of graphitic samples\nare more sensitive to the orientation of the layers than to their number."
    },
    {
        "anchor": "Near-field imaging of spin-locked edge states in all-dielectric\n  topological metasurfaces: A new class of phenomena stemming from topological states of quantum matter\nhas recently found a variety of analogies in classical systems. Spin-locking\nand one-way propagation have been shown to drastically alter our view on\nscattering of electromagnetic waves, thus offering an unprecedented robustness\nto defects and disorder. Despite these successes, bringing these new ideas to\npractical grounds meets a number of serious limitations. In photonics, when it\nis crucial to implement topological photonic devices on a chip, two major\nchallenges are associated with electromagnetic dissipation into heat and\nout-of-plane radiation into free space. Both these mechanisms may destroy the\ntopological state and seriously affect the device performance. Here we\nexperimentally demonstrate that the topological order for light can be\nimplemented in all-dielectric on-chip prototype metasurfaces, which mitigate\nthe effect of Ohmic losses by using exclusively dielectric materials, and\nreveal that coupling of the system to the radiative continuum does not affect\nthe topological properties. Spin-Hall effect of light for spin-polarized\ntopological edge states is revealed through near-field spectroscopy\nmeasurements.",
        "positive": "Effect of cobalt substitution on structural, impedance, ferroelectric\n  and magnetic properties of multiferroic Bi_2Fe_4O_9 ceramics: Structural, impedance, ferroelectric and magnetic properties were examined in\nmultiferroic Bi_{2}Fe_{4(1-x)}Co_{4x}O_{9} (0$\\leq$x$\\leq$0.02) ceramics\nsynthesized via solid-state reaction method. X-ray diffraction analysis and\nRietveld refinement showed secondary phase formation (for x$\\geq$0.01) which\nwas subsequently confirmed from room temperature Raman spectroscopy study. The\nfrequency dependence of impedance and electric modulus of the material showed\nthe presence of non-Debye type relaxation in all the samples. The values of the\nactivation energies calculated from imaginary impedance and modulus lie in the\nrange of 0.92-0.99 eV which confirmed that the oxygen vacancies play an\nimportant role in the conduction mechanism. Moreover, suitable amount of Co\nsubstitution significantly enhanced the remnant polarisation (2P_{r}) from\n0.1193 $\\mu$C/cm^{2} (x=0) to 0.2776 $\\mu$C/cm^{2} (x=0.02). Besides, room\ntemperature M-H measurement showed improved ferromagnetic hysteresis loop for\nall the modified samples. The remnant magnetization (M_{r}) and coercive field\n(H_{c}) increased from 0.0007 emu/gm and 42 Oe for x=0 to 0.1401 emu/gm and 296\nOe for x=0.02. The improved ferroelectricity was due to Co 3d-O 2p\nhybridization and enhanced magnetization originated from the partial\nsubstitution of Co^{3+} ions leading to breakdown of balance between the\nanti-parallel sub lattice magnetization of Fe^{3+} ions."
    },
    {
        "anchor": "Magnetic properties of La(0.67)Sr(0.33)MnO3/BiFeO3(001) heterojunctions:\n  chemically abrupt versus atomic intermixed interface: Using first-principles density-functional calculations, we address the\nmagnetic properties of the ferromagnet/antiferromagnet\nLa(0.67)Sr(0.33)MnO3/BiFeO3(001) heterojunctions, and investigate possible\ndriving mechanisms for a ferromagnetic (FM) interfacial ordering of the Fe\nspins recently observed experimentally. We find that the chemically abrupt\ndefect-free La(0.67)Sr(0.33)MnO3/BiFeO3(001) heterojunction displays, as ground\nstate, an ordering with compensated Fe spins. Cation Fe/Mn intermixing at the\ninterface tends to favour, instead, a FM interfacial order of the Fe spins,\ncoupled antiferromagnetically to the bulk La(0.67)Sr(0.33)MnO3 spins, as\nobserved experimentally. Such trends are understood based on a model\ndescription of the energetics of the exchange interactions.",
        "positive": "Effect of reduced local lattice disorder on the magnetic properties of\n  B-site substituted La0.8Sr0.2MnO3: Disorder induced by chemical inhomogeneity and Jahn-Teller (JT) distortions\nis often observed in mixed valence perovskite manganites. The main reasons for\nthe evolution of this disorder are connected with the cationic size differences\nand the ratio between JT active and non-JT active ions. The quenched disorder\nleads to a spin-cluster state above the magnetic transition temperature. The\neffect of Cu, a B-site substitution in the La0.8Sr0.2MnO3 compound, on the\ndisordered phase has been addressed here. X-ray powder diffraction reveals\nrhombohedral (R-3c) structures for the two compounds with negligible change of\nlattice volume. The chemical compositions of the two compounds were verified by\nion beam analysis technique. With the change of electronic bandwidth, the\nmagnetic phase transition temperature has been tuned towards room temperature\n(318 K), an important requirement for room temperature magnetic refrigeration.\nHowever, a small decrease of the isothermal entropy was observed with\nCu-substitution, related to the decrease of the saturation magnetization."
    },
    {
        "anchor": "Spin-flip hot spots in ultrathin films of monovalent metals: Enhancement\n  and anisotropy of the Elliott-Yafet parameter: In contrast to the long-known fact that spin-flip hot spots, i.e., special\n\\vc{k}-points on the Fermi surface showing a high spin-mixing parameter, do not\noccur in the bulk of monovalent (noble and alkali) metals, we found them on the\nsurface Brillouin-zone boundary of ultrathin films of these metals.\nDensity-functional calculations within the Korringa-Kohn-Rostoker Green\nfunction method for ultrathin (001) oriented Cu, Ag, and Au films of 10-layer\nthickness show that the region around the hot spots can have a substantial\ncontribution, e.g.\\ 52\\% in Au(001), to the integrated spin-mixing parameter,\nthat could lead to a significant enhancement of the spin-relaxation rate or\nspin-Hall angle in thin films. Owing to the appearance of spin-flip hot-spots,\na large anisotropy of the Elliott-Yafet parameter [50\\% for Au(001)] is also\nfound in these systems. The findings are important for spintronics applications\nin which noble-metals are frequently used and in which the dimensionality of\nthe sample is reduced.",
        "positive": "Spin-Phonon coupling in Y$_2$NiMnO$_6$ double perovskite probed by Raman\n  spectroscopy: We performed Raman spectroscopy measurements under temperature changes from\n10 K up to 850 K to probe the phonon-spin coupling in Y$_2$NiMnO$_6$. The\nspin-phonon coupling was observed as a softening of the stretching mode,\nindicating this phonon stabilizes the magnetic interaction. The result\nindicates the rare earth ionic radius in Re$_2$NiMnO$_6$ double perovskites is\nnot the unique parameter influencing the spin-coupling magnitude."
    },
    {
        "anchor": "Ultrafast Photo-induced Phase Change in SnSe: Time-resolved multi-terahertz (THz) spectroscopy is used to observe an\nultrafast, non-thermal electronic phase change in SnSe driven by interband\nphotoexcitation with 1.55 eV pump photons. The transient THz photoconductivity\nspectrum is found to be Lorentzian-like, indicating charge localization and\nphase segregation. The rise of photoconductivity is bimodal in nature, with\nboth a fast and slow component due to excitation into multiple bands and\nsubsequent intervalley scattering. The THz conductivity magnitude, dynamics,\nand spectra show a drastic change in character at a critical excitation fluence\nof approximately 6 mJ/cm^2 due to a photo-induced phase segregation and a\nmacroscopic collapse of the band gap.",
        "positive": "When does deep learning fail and how to tackle it? A critical analysis\n  on polymer sequence-property surrogate models: Deep learning models are gaining popularity and potency in predicting polymer\nproperties. These models can be built using pre-existing data and are useful\nfor the rapid prediction of polymer properties. However, the performance of a\ndeep learning model is intricately connected to its topology and the volume of\ntraining data. There is no facile protocol available to select a deep learning\narchitecture, and there is a lack of a large volume of homogeneous\nsequence-property data of polymers. These two factors are the primary\nbottleneck for the efficient development of deep learning models. Here we\nassess the severity of these factors and propose new algorithms to address\nthem. We show that a linear layer-by-layer expansion of a neural network can\nhelp in identifying the best neural network topology for a given problem.\nMoreover, we map the discrete sequence space of a polymer to a continuous\none-dimensional latent space using a machine learning pipeline to identify\nminimal data points for building a universal deep learning model. We implement\nthese approaches for three representative cases of building sequence-property\nsurrogate models, viz., the single-molecule radius of gyration of a copolymer,\nadhesive free energy of a copolymer, and copolymer compatibilizer,\ndemonstrating the generality of the proposed strategies. This work establishes\nefficient methods for building universal deep learning models with minimal data\nand hyperparameters for predicting sequence-defined properties of polymers."
    },
    {
        "anchor": "First-principles study of ferroelectricity and isotope effects in\n  H-bonded KDP crystals: By means of extensive first-principles calculations we studied the\nferroelectric phase transition and the associated isotope effect in KH2PO4\n(KDP)",
        "positive": "Adsorption of ammonia at GaN(0001) surface in the mixed ammonia/hydrogen\n  ambient - a summary of ab initio data: Adsorption of ammonia at NH3/NH2/H covered GaN(0001) surface was analyzed\nusing results of ab initio calculations. The whole configuration space of\npartially NH3/NH2/H covered GaN(0001) surface was divided into zones\ndifferently pinned Fermi level: at Ga broken bond state for dominantly bare\nsurface (region I), at VBM for NH2 and H covered (region II), and at CBM for\nNH3 covered surface (region III). The extensive ab intio calculations show\nvalidity of electron counting rule (ECR) for all mixed coverage, for bordering\nthese three regions. The adsorption was analyzed using newly identified\ndependence of the adsorption energy on the charge transfer at the surface. For\nregion I and II ammonia adsorb dissociatively, disintegrating into H adatom and\nHN2 radical for large fraction of vacant sites while for high coverage the\nammonia adsorption is molecular. The dissociative adsorption energy strongly\ndepends on the Fermi level at the surface (pinned) and in the bulk (unpinned)\nwhile the molecular adsorption energy is determined by bonding to surface only,\nin accordance to the recently published theory. The molecular adsorption is\ndetermined by the energy of covalent bonding to the surface. Ammonia adsorption\nin region III (Fermi level pinned at CBM) leads to unstable configuration both\nmolecular and dissociative which is explained by the fact that Ga-broken bond\nsites are doubly occupied by electrons. The adsorbing ammonia brings 8\nelectrons to the surface, necessitating transfer of the electrons from\nGa-broken bond state to Fermi level, energetically costly process. Adsorption\nof ammonia at H-covered site leads to creation of NH2 radical at the surface\nand escape of H2 molecule. The process energy is close to 0.12 eV, thus not\nlarge, but the inverse process is not possible due to escape of the hydrogen\nmolecule."
    },
    {
        "anchor": "High-throughput screening of small-molecule adsorption in MOF: Using high-throughput screening coupled with state-of-the-art van der Waals\ndensity functional theory, we investigate the adsorption properties of four\nimportant molecules, H_2, CO_2, CH_4, and H_2O in MOF-74-M with M = Be, Mg, Al,\nCa, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Zr, Nb, Ru, Rh, Pd, La, W, Os,\nIr, and Pt. We show that high-throughput techniques can aid in speeding up the\ndevelopment and refinement of effective materials for hydrogen storage, carbon\ncapture, and gas separation. The exploration of the configurational adsorption\nspace allows us to extract crucial information concerning, for example, the\ncompetition of water with CO_2 for the adsorption \"pockets.\" We find that only\na few noble metals---Rh, Pd, Os, Ir, and Pt---favor the adsorption of CO_2 and\nhence are potential candidates for effective carbon-capture materials. Our\nfindings further reveal significant differences in the binding characteristics\nof H_2, CO_2, CH_4, and H_2O within the MOF structure, indicating that\nmolecular blends can be successfully separated by these nano-porous materials.",
        "positive": "Developments and Further Applications of Ephemeral Data Derived\n  Potentials: Machine-learned interatomic potentials are fast becoming an indispensable\ntool in computational materials science. One approach is the ephemeral\ndata-derived potential (EDDP), which was designed to accelerate atomistic\nstructure prediction. The EDDP is simple and cost-efficient. It relies on\ntraining data generated in small unit cells and is fit using a lightweight\nneural network, leading to smooth interactions which exhibit the robust\ntransferability essential for structure prediction. Here, we present a variety\nof applications of EDDPs, enabled by recent developments of the open-source\nEDDP software. New features include interfaces to phonon and molecular dynamics\ncodes, as well as deployment of the ensemble deviation for estimating the\nconfidence in EDDP predictions. Through case studies ranging from elemental\ncarbon and lead to the binary scandium hydride and the ternary zinc cyanide, we\ndemonstrate that EDDPs can be trained to cover wide ranges of pressures and\nstoichiometries, and used to evaluate phonons, phase diagrams, superionicity,\nand thermal expansion. These developments complement continued success in\naccelerated structure prediction."
    },
    {
        "anchor": "Toward a Comprehensive Model of Snow Crystal Growth: 4. Measurements of\n  Diffusion-limited Growth at -15 C: We present measurements of the diffusion-limited growth of ice crystals from\nwater vapor at different supersaturation levels in air at a temperature of -15\nC. Starting with thin, c-axis ice needle crystals, the subsequent growth\nmorphologies ranged from blocky structures on the needle tips (at low\nsupersaturation) to thin faceted plates on the needle tips (at high\nsupersaturation). We successfully modeled the experimental data, reproducing\nboth growth rates and growth morphologies, using a cellular-automata method\nthat yields faceted crystalline structures in diffusion-limited growth. From\nthis quantitative analysis of well-controlled experimental measurements, we\nwere able to extract information about the attachment coefficients governing\nice growth under different circumstances. The results strongly support previous\nwork indicating that the attachment coefficient on the prism surface is a\nfunction of the width of the prism facet. Including this behavior, we created a\ncomprehensive model at -15 C that explains all the experimental data. To our\nknowledge, this is the first demonstration of a kinetic model that reproduces a\nrange of diffusion-limited ice growth behaviors as a function of\nsupersaturation.",
        "positive": "Ultrafast atomic transport in recrystallizing ultrafine grained Ni: We studied tracer self-diffusion in ultrafine grained Ni prepared by high\npressure torsion. Two Ni materials of low (99.6 wt. %) and high (99.99 wt. %)\npurity levels were investigated. While the ultrafine grained structure of less\npure Ni remained stable during diffusion annealing, recrystallization and\nsubsequent grain growth occurred in high purity Ni at the same annealing\nconditions. Nevertheless, qualitatively similar ultrafast diffusion rates were\nmeasured in the samples of both purity levels. In high purity Ni, the kinetics\nof recrystallization was found to deviate strongly from the predictions of the\nJohnson-Mehl-Avrami-Kolmogorov theory. Moreover, the ultrafast diffusion paths\nwithstood the recrystallization process. A model which accounts for solute\nredistribution in front of the moving boundary is suggested. Retaining of\ndeformation-induced ultrafast diffusion paths in recrystallized Ni is explained\nby a specific mechanism of enhanced stability of the residual ultrafine grained\nfraction against recrystallization."
    },
    {
        "anchor": "Correcting nonlinear drift distortion of scanning probe microscopy from\n  image pairs with orthogonal scan directions: Unwanted motion of the probe with respect to the sample is a ubiquitous\nproblem in scanning probe microscopy, causing both linear and nonlinear\nartifacts in experimental images. We have designed a procedure to correct these\nartifacts by using orthogonal scan pairs to align each measurement line-by-line\nalong the slow scan direction. We demonstrate the accuracy of our algorithm on\nboth synthetic and experimental data and provide an implementation of our\nmethod.",
        "positive": "Temperature- and doping-dependent roles of valleys in thermoelectric\n  performance of SnSe: a first-principles study: We theoretically investigate how each orbital and valley play a role for high\nthermoelectric performance of SnSe. In the hole-doped regime, two kinds of\nvalence band valleys contribute to its transport properties: one is the valley\nnear the U-Z line, mainly consisting of the Se-$p_z$ orbitals, and the other is\nthe one along the $\\Gamma$-Y line, mainly consisting of the Se-$p_y$ orbitals.\nWhereas the former valley plays a major role in determining the transport\nproperties at room temperature, the latter one also offers comparable\ncontribution and so the band structure exhibits multi-valley character by\nincreasing the temperature. In the electron-doped regime, the conduction band\nvalley around the $\\Gamma$ point solely contributes to the thermoelectric\nperformance, where the quasi-one-dimensional electronic structure along the\n$a$-axis is crucial. This study provides an important knowledge for the\nthermoelectric properties of SnSe, and will be useful for future search of\nhigh-performance thermoelectric materials."
    },
    {
        "anchor": "Enhancement of superconductivity in organic-inorganic hybrid topological\n  materials: Inducing or enhancing superconductivity in topological materials is an\nimportant route toward topological superconductivity. Reducing the thickness of\ntransition metal dichalcogenides (e.g. WTe2 and MoTe2) has provided an\nimportant pathway to engineer superconductivity in topological matters; for\ninstance, emergent superconductivity with Tc=0.82 K was observed in monolayer\nWTe2 which also hosts intriguing quantum spin Hall effect, although the bulk\ncrystal is nonsuperconducting. However, such monolayer sample is difficult to\nobtain, unstable in air, and with extremely low Tc, which could pose a grand\nchallenge for practical applications. Here we report an experimentally\nconvenient approach to control the interlayer coupling to achieve tailored\ntopological properties, enhanced superconductivity and good sample stability\nthrough organic cation intercalation of the Weyl semimetals MoTe2 and WTe2. The\nas-formed organic-inorganic hybrid crystals are weak topological insulators\nwith enhanced Tc of 7.0 K for intercalated MoTe2 (0.25 K for pristine crystal)\nand 2.3 K for intercalated WTe2 (2.8 times compared to monolayer WTe2). Such\norganic-cationintercalation method can be readily applied to many other layered\ncrystals, providing a new pathway for manipulating their electronic,\ntopological and superconducting properties.",
        "positive": "Fabrication, Dynamics, and Electrical Properties of Insulated SPM Probes\n  for Electrical and Electromechanical Imaging in Liquids: Insulated cantilever probes with a high aspect ratio conducting apex have\nbeen fabricated and their dynamic and electrical properties analyzed. The\ncantilevers were coated with silicon dioxide and a via was fabricated through\nthe oxide at the tip apex and backfilled with tungsten to create an insulated\nprobe with a conducting tip. The stiffness and Q-factor of the cantilevers\nincreased after the modifications and their resonances shifted to higher\nfrequencies. The coupling strength between the cantilever and the coating are\ndetermined. The applications to conductive and electromechanical imaging of\nferroelectric domains are illustrated, and a probe apex repair process is\ndemonstrated."
    },
    {
        "anchor": "All electrical manipulation of magnetization dynamics in a ferromagnet\n  by antiferromagnets with anisotropic spin Hall effects: We investigate spin-orbit torques of metallic CuAu-I-type antiferromagnets\nusing spin-torque ferromagnetic resonance tuned by a dc-bias current. The\nobserved spin torques predominantly arise from diffusive transport of spin\ncurrent generated by the spin Hall effect. We find a growth-orientation\ndependence of the spin torques by studying epitaxial samples, which may be\ncorrelated to the anisotropy of the spin Hall effect. The observed anisotropy\nis consistent with first-principles calculations on the intrinsic spin Hall\neffect. Our work demonstrates large tunable spin-orbit effects in\nmagnetically-ordered materials.",
        "positive": "Hot-carrier trap-limited transport in switching chalcogenides: Chalcogenide materials have received great attention in the last decade owing\nto their application in new memory systems. Recently, phase-change memories\nhave, in fact, reached the early stages of production. In spite of the\nindustrial exploitation of such materials, the physical processes governing the\nswitching mechanism are still debated. In this paper we work out a complete and\nconsistent model for transport in amorphous chalcogenide materials based on\ntrap-limited conduction accompanied by carrier heating. A previous model is\nhere extended to include position-dependent carrier concentration and field,\nconsistently linked by the Poisson equation. The results of the new model\nreproduce the experimental electrical characteristics and their dependences on\nthe device length and temperature. Furthermore, the model provides a sound\nphysical interpretation of the switching phenomenon and is able to give an\nestimate of the threshold condition in terms of the material parameters, a\npiece of information of great technological interest."
    },
    {
        "anchor": "Convolutional neural network-assisted recognition of nanoscale L12\n  ordered structures in face-centred cubic alloys: Nanoscale L12-type ordered structures are widely used in face-centred cubic\n(FCC) alloys to exploit their hardening capacity and thereby improve mechanical\nproperties. These fine-scale particles are typically fully coherent with matrix\nwith the same atomic configuration disregarding chemical species, which makes\nthem challenging to be characterized. Spatial distribution maps (SDMs) are used\nto probe local order by interrogating the three-dimensional (3D) distribution\nof atoms within reconstructed atom probe tomography (APT) data. However, it is\nalmost impossible to manually analyse the complete point cloud ($>10$ million)\nin search for the partial crystallographic information retained within the\ndata. Here, we proposed an intelligent L12-ordered structure recognition method\nbased on convolutional neural networks (CNNs). The SDMs of a simulated\nL12-ordered structure and the FCC matrix were firstly generated. These\nsimulated images combined with a small amount of experimental data were used to\ntrain a CNN-based L12-ordered structure recognition model. Finally, the\napproach was successfully applied to reveal the 3D distribution of L12-type\n$\\delta^\\prime$-Al3(LiMg) nanoparticles with an average radius of 2.54 nm in a\nFCC Al-Li-Mg system. The minimum radius of detectable nanodomain is even down\nto 5 \\r{A}. The proposed CNN-APT method is promising to be extended to\nrecognize other nanoscale ordered structures and even more-challenging\nshort-range ordered phenomena in the near future.",
        "positive": "Thermoelectric transport in strained Si and Si/Ge heterostructures: The anisotropic thermoelectric transport properties of bulk silicon strained\nin [111]-direction were studied by detailed first-principles calculations\nfocussing on a possible enhancement of the power factor. Electron as well as\nhole doping were examined in a broad doping and temperature range. At low\ntemperature and low doping an enhancement of the power factor was obtained for\ncompressive and tensile strain in the electron-doped case and for compressive\nstrain in the hole-doped case. For the thermoelectrically more important high\ntemperature and high doping regime a slight enhancement of the power factor was\nonly found under small compressive strain with the power factor overall being\nrobust against applied strain. To extend our findings the anisotropic\nthermoelectric transport of an [111]-oriented Si/Ge superlattice was\ninvestigated. Here, the cross-plane power factor under hole-doping was\ndrastically suppressed due to quantum-well effects, while under electron-doping\nan enhanced power factor was found. With that, we state a figure of merit of\nZT$=0.2$ and ZT$=1.4$ at $T=\\unit[300]{K}$ and $T=\\unit[900]{K}$ for the\nelectron-doped [111]-oriented Si/Ge superlattice. All results are discussed in\nterms of band structure features."
    },
    {
        "anchor": "Symmetry changes at the ferroelectric transition in the multiferroic\n  YMnO3: We have identified, for the first time, the change in symmetry at the\nferroelectric transition TFE near 1023K of the ferroelectromagnet YMnO3. This\ntransition takes place 300K below the transition to the centrosymmetric state\nat TIP. Single crystal synchrotron diffraction coupled to a group theoretical\nanalysis show that the paraelectric intermediate phase between TIP and TFE has\nP63/mcm symmetry. This proves that YMnO3 is a proper ferroelectric and not an\nimproper ferroelectric, as suggested by a previous group theoretical\nassignment. The origin of the ferroelectricity is caused by a correlated\ntilting of the MnO5 polyhedra along the (100), (110) and (010) directions",
        "positive": "Hydrogen Embrittlement of Aluminum: the Crucial Role of Vacancies: We report first-principles calculations which demonstrate that vacancies can\ncombine with hydrogen impurities in bulk aluminum and play a crucial role in\nthe embrittlement of this prototypical ductile solid. Our studies of\nhydrogen-induced vacancy superabundant formation and vacancy clusterization in\naluminum lead to the conclusion that a large number of H atoms (up to twelve)\ncan be trapped at a single vacancy, which over-compensates the energy cost to\nform the defect. In the presence of trapped H atoms, three nearest-neighbor\nsingle vacancies which normally would repel each other, aggregate to form a\ntrivacancy on the slip plane of Al, acting as embryos for microvoids and cracks\nand resulting in ductile rupture along the these planes."
    },
    {
        "anchor": "Mixed Stochastic-Deterministic Approach for Many-Body Perturbation\n  Theory Calculations: We present an approach for GW calculations of quasiparticle energies with\nquasi-quadratic scaling by approximating high-energy contributions to the\nGreen's function in its Lehmann representation with effective stochastic\nvectors. The method is easy to implement without altering the GW code,\nconverges rapidly with stochastic parameters, and treats systems of various\ndimensionality and screening response. Our calculations on a 5.75$^\\circ$\ntwisted MoS$_2$ bilayer show how large-scale GW methods include geometry\nrelaxations and electronic correlations on an equal basis in structurally\nnontrivial materials.",
        "positive": "Electronic Properties of Group III-a Nitride Sheets by Molecular\n  Simulation: We have performed first principles total energy calculations to investigate\nthe structural and reactivity parameters of novel N12X12H12 (X=B, Al, Ga, In,\nTI) nitrides, in their coronene-like (C24H12) structure to simulate these\nsheets. The exchange and correlations potential energies are treated in the\ngeneralized gradient approximation (GGA), and the local density approximation\nwithin the parameterization of Perdew-Wang and Perdew-Burke-Ernzerhof (PWC,\nPBE) and the doubly polarized atomic base (DNP). The chemical potential,\nhardness and electrophilicy index, as well as bond length are reported. The\nbond length of the structures is similar to the bulk. The gap between the HOMO\nand LUMO decreases from BN (5.18eV) to TlN (1.76 eV). At the same time, the\npolarity increases except for TlN."
    },
    {
        "anchor": "Anomalous Frequency Trends in MoS2 Thin Films Attributed to Surface\n  Effects: The layered dichalcogenide MoS2 has many unique physical properties in low\ndimensions. Recent experimental Raman spectroscopies report an anomalous blue\nshift of the in-plane E2g1 mode with decreasing thickness, a trend that is not\nunderstood. Here, we combine experimental Raman scattering and theoretical\nstudies to clarify and explain this trend. Special attention is given to\nunderstanding the surface effect on Raman frequencies by using a force\nconstants model based on first-principles calculations. Surface effects refer\nto the larger Mo-S force constants at the surface of thin film MoS2, which\nresults from a loss of neighbours in adjacent MoS2 layers. Without surface\neffects, the frequencies of both out-of-plane A1g and in-plane E2g1 modes\ndecrease with decreasing thickness. However, the E2g1 mode blue shifts while\nthe A1g mode red shifts once the surface effect is included, in agreement with\nthe experiment. Our results show that competition between the thickness effect\nand the surface effect determines the mechanical properties of two-dimensional\nMoS2, which we believe applies to other layered materials.",
        "positive": "Study on the composition optimization method for improving the fluidity\n  of cast Ti$_2$AlNb alloy and its mechanism: In this paper, the effects of Al, Nb main elements, Fe, Mo, W, Co, B, Si and\ntheir contents on the fluidity of Ti-22Al-25Nb alloy were investigated. The\ncomposition that was beneficial to improve the fluidity was screened through\nthe thermodynamic software calculating thermophysical parameters affecting the\nfluidity of Ti$_2$AlNb alloy, the numerical simulation test of its fluidity and\nthe verification test of the fluidity of optimized alloys. Finally, the\nimprovement mechanism of the alloy fluidity was discussed. Results showed that\nthe appropriate reduction of Nb element was better than Al element for the\nimprovement of fluidity. The addition of trace Fe, B and Si elements were\nbeneficial to the improvement of fluidity, the improvement effect of B element\nwas best, while the addition of trace Mo, W, Co were not conducive to the\nimprovement of fluidity. The cessation mechanism of Ti$_2$AlNb alloy is the\ncessation mechanism of the alloy with a wide crystallization temperature range.\nThe composition which was most beneficial to improve the fluidity was\nTi-22Al-24Nb-0.1B. The main reasons for the improvement of the fluidity had two\nsides: on the one hand, the reduction of 1at% Nb and the addition of 0.1at% B\nnot only increased the superheat and crystallization latent heat of the alloy,\nbut also reduced the melt viscosity and thermal conductivity, thus improving\nthe fluidity. On the other hand, the TiB phase refined the grains, the fine\ngrains prevented the dendrite from growing into developed dendrite networks,\ninhibited the adverse effect of the increase in the width of the solidification\nzone on the fluidity, reduced the flow resistance of the molten metal, and\nfurther improved the fluidity of the alloy."
    },
    {
        "anchor": "Straight cracks in dynamic brittle fracture: We study the dynamics of cracks in brittle materials when the velocity of the\ncrack is comparable to the sound velocity by means of lattice simulations.\nInertial and damped dynamics are analyzed. It is shown that dissipation\nstrongly influences the shape of the crack. While inertial cracks are highly\nunstable, dissipation can stabilize straight cracks. Our results can help to\nexplain recent experiments on PMMA.",
        "positive": "Low energy paths for octahedral tilting in inorganic halide perovskites: Instabilities relating to cooperative octahedral tilting is common in\nmaterials with perovskite structures, and in particular in the sub class of\nhalide perovskites. In this work, the energetics of octahedral tilting in the\ninorganic metal halide perovskites CsPbI$_3$ and CsSnI$_3$ are investigated\nusing first-principles density functional theory calculations. Several low\nenergy paths between symmetry equivalent variants of the stable orthorhombic\n(\\textit{Pnma}) perovskite variant are identified and investigated. The results\nare in favor of the presence of dynamic disorder in the octahedral tilting\nphase transitions of inorganic halide perovskites. In particular, one specific\ntype of path, corresponding to an out-of-phase \"tilt switch\", is found to have\nsignificantly lower energy barrier than the others, which indicates the\nexistence of a temperature range where the dynamic fluctuations of the\noctahedra follow only this type of path. This could produce a time averaged\nstructure corresponding to the intermediate tetragonal (\\textit{P4/mbm})\nstructure observed in experiments. Deficiencies of the commonly employed simple\none-dimensional \"double well\" potentials in describing the dynamics of the\noctahedra are pointed out and discussed."
    },
    {
        "anchor": "Tunable magnetic exchange interactions in manganese-doped inverted\n  core/shell ZnSe/CdSe nanocrystals: Magnetic doping of semiconductor nanostructures is actively pursued for\napplications in magnetic memory and spin-based electronics. Central to these\nefforts is a drive to control the interaction strength between carriers\n(electrons and holes) and the embedded magnetic atoms. In this respect,\ncolloidal nanocrystal heterostructures provide great flexibility via\ngrowth-controlled `engineering' of electron and hole wavefunctions within\nindividual nanocrystals. Here we demonstrate a widely tunable magnetic sp-d\nexchange interaction between electron-hole excitations (excitons) and\nparamagnetic manganese ions using `inverted' core-shell nanocrystals composed\nof Mn-doped ZnSe cores overcoated with undoped shells of narrower-gap CdSe.\nMagnetic circular dichroism studies reveal giant Zeeman spin splittings of the\nband-edge exciton that, surprisingly, are tunable in both magnitude and sign.\nEffective exciton g-factors are controllably tuned from -200 to +30 solely by\nincreasing the CdSe shell thickness, demonstrating that strong quantum\nconfinement and wavefunction engineering in heterostructured nanocrystal\nmaterials can be utilized to manipulate carrier-Mn wavefunction overlap and the\nsp-d exchange parameters themselves.",
        "positive": "Thermally-Assisted Current-Driven Domain Wall Motion: Starting from the stochastic Landau-Lifschitz-Gilbert equation, we derive\nLangevin equations that describe the nonzero-temperature dynamics of a rigid\ndomain wall. We derive an expression for the average drift velocity of the\ndomain wall as a function of the applied current, and find qualitative\nagreement with recent magnetic semiconductor experiments. Our model implies\nthat at any nonzero temperature the average domain-wall velocity initially\nvaries linearly with current, even in the absence of non-adiabatic spin\ntorques."
    },
    {
        "anchor": "Comparison of micromagnetic parameters of ferromagnetic semiconductors\n  (Ga,Mn)(As,P) and (Ga,Mn)As: We report on the determination of micromagnetic parameters of epilayers of\nthe ferromagnetic semiconductor (Ga,Mn)As, which has easy axis in the sample\nplane, and (Ga,Mn)(As,P) which has easy axis perpendicular to the sample plane.\nWe use an optical analog of ferromagnetic resonance where the\nlaser-pulse-induced precession of magnetization is measured directly in the\ntime domain. By the analysis of a single set of pump-and-probe magneto-optical\ndata we determined the magnetic anisotropy fields, the spin stiffness and the\nGilbert damping constant in these two materials. We show that incorporation of\n10% of phosphorus in (Ga,Mn)As with 6% of manganese leads not only to the\nexpected sign change of the perpendicular to plane anisotropy field but also to\nan increase of the Gilbert damping and to a reduction of the spin stiffness.\nThe observed changes in the micromagnetic parameters upon incorporating P in\n(Ga,Mn)As are consistent with the reduced hole density, conductivity, and Curie\ntemperature of the (Ga,Mn)(As,P) material. We report that the magnetization\nprecession damping is stronger for the n = 1 spin wave resonance mode than for\nthe n = 0 uniform magnetization precession mode.",
        "positive": "Thermopower modulation clarification of the intrinsic effective mass in\n  a transparent oxide semiconductor, BaSnO3: Although there are so many reports on the carrier effective mass (m*) of a\ntransparent oxide semiconductor BaSnO3, it is almost impossible to know the\nintrinsic m* value because the reported m* values are scattered from 0.06 to\n3.7 m0. Here we successfully clarified the intrinsic m* of BaSnO3, m*=0.40 0.01\nm0, by the thermopower modulation clarification method. We also found the\nthreshold of degenerate/non-degenerate semiconductor of BaSnO3; At the\nthreshold, the thermopower value of both La-doped BaSnO3 and BaSnO3 TFT\nstructure was 240 microvolt k-1, bulk carrier concentration was 1.4E19 cm-3,\nand two-dimensional sheet carrier concentration was 1.8E12 cm-2. When the EF\nlocates above the parabolic shaped conduction band bottom, rather high mobility\nwas observed. On the contrary, very low carrier mobility was observed when the\nEF lays below the threshold, most likely due to that the tail states suppress\nthe carrier mobility. The present results are useful for further development of\nBaSnO3 based oxide electronics."
    },
    {
        "anchor": "Phonon anharmonicity and thermal conductivity of two-dimensional van der\n  Waals materials: A review: Two-dimensional (2D) van der Waals (vdW) materials have extraordinary thermal\nproperties due to the effect of quantum confinement, making them promising for\nthermoelectric energy conversion and thermal management in microelectronic\ndevices. In this review, the mechanism of phonon anharmonicity originating from\nthree- and four-phonon interactions is derived. The phonon anharmonicity of 2D\nvdW materials, involving the Gr\\\"uneisen parameter, phonon lifetime, and\nthermal conductivity, is summarized and derived in detail. The size-dependent\nthermal conductivity of representative 2D vdW materials is discussed\nexperimentally and theoretically. This review will present fundamental and\nadvanced knowledge on how to evaluate the phonon anharmonicity in 2D vdW\nmaterials, which will aid the design of new structures and materials for\napplications related to energy transfer and conversion.",
        "positive": "Charge density wave surface reconstruction in a van der Waals layered\n  material: Surface reconstruction plays a vital role in determining the surface\nelectronic structure and chemistry of semiconductors and metal oxides. However,\nit has been commonly believed that surface reconstruction does not occur in van\nder Waals layered materials, as they do not undergo significant bond breaking\nduring surface formation. In this study, we present evidence that charge\ndensity wave (CDW) order in these materials can, in fact, cause CDW surface\nreconstruction through interlayer coupling. Using density functional theory\ncalculations on the 1T-TaS2 surface, we reveal that CDW reconstruction,\ninvolving concerted small atomic displacements in the subsurface layer, results\nin a significant modification of the surface electronic structure, transforming\nit from a Mott insulator to a band insulator. This new form of surface\nreconstruction explains several previously unexplained observations on the\n1T-TaS2 surface and has important implications for interpreting surface\nphenomena in CDW-ordered layered materials."
    },
    {
        "anchor": "Phonon anharmonicity and negative thermal expansion in SnSe: The anharmonic phonon properties of SnSe in the Pnma phase were investigated\nwith a combination of experiments and first-principles simulations. Using\ninelastic neutron scattering (INS) and nuclear resonant inelastic X-ray\nscattering (NRIXS), we have measured the phonon dispersions and density of\nstates (DOS) and their temperature dependence, which revealed a strong,\ninhomogeneous shift and broadening of the spectrum on warming. First-principles\nsimulations were performed to rationalize these measurements, and to explain\nthe previously reported anisotropic thermal expansion, in particular the\nnegative thermal expansion within the Sn-Se bilayers. Including the anisotropic\nstrain dependence of the phonon free energy, in addition to the electronic\nground state energy, is essential to reproduce the negative thermal expansion.\nFrom the phonon DOS obtained with INS and additional calorimetry measurements,\nwe quantify the harmonic, dilational, and anharmonic components of the phonon\nentropy, heat capacity, and free energy. The origin of the anharmonic phonon\nthermodynamics is linked to the electronic structure.",
        "positive": "Scanning mid-IR-laser microscopy: an efficient tool for materials\n  studies in silicon-based photonics and photovoltaics: A method of scanning mid-IR-laser microscopy has recently been proposed for\nthe investigation of large-scale electrically and recombination-active defects\nin semiconductors and non-destructive inspection of semiconductor materials and\nstructures in the industries of microelectronics and photovoltaics. The basis\nfor this development was laid with a wide cycle of investigations on low-angle\nmid-IR-light scattering in semiconductors. The essence of the technical idea\nwas to apply the dark-field method for spatial filtering of the scattered light\nin the scanning mid-IR-laser microscope together with the local photoexcitation\nof excess carriers within a small domain in a studied sample, thus forming an\nartificial source of scattering of the probe IR light for the recombination\ncontrast imaging of defects.\n  The current paper presents three contrasting examples of application of the\nabove technique for defect visualization in silicon-based materials designed\nfor photovoltaics and photonics which demonstrate that this technique might be\nan efficient tool for both defect investigation and industrial testing of\nsemiconducting materials."
    },
    {
        "anchor": "Emphanitic anharmonicity in PbSe at high temperature and the anomalous\n  electronic properties in the PbQ (Q=S, Se, Te) system: The temperature dependence of the local structure of PbSe has been\ninvestigated using pair distribution function (PDF) analysis of x-ray and\nneutron powder diffraction data and density functional theory (DFT)\ncalculations. Observation of non-Gaussian PDF peaks at high temperature\nindicates the presence of significant anharmonicity, which can be modeled as Pb\noff-centering along [100] directions that grows on warming similar to the\nbehavior seen in PbTe and PbS and sometimes called emphanisis. Interestingly,\nthe emphanitic response is smaller in PbSe than in both PbS and PbTe indicating\na non-monotonic response with chalcogen atomic number in the PbQ (Q=S, Se, Te)\nseries. The DFT calculations indicate a correlation between band gap and the\namplitude of [100] dipolar distortion, suggesting that emphanisis may be behind\nthe anomalous composition and temperature dependencies of the band gaps in this\nseries.",
        "positive": "Exhaustive List of Topological Hourglass Band Crossings in 230 Space\n  Groups: Topological semimetals with band crossings (BCs) near the Fermi level have\nattracted intense research activities in the past several years. Among various\nBCs, those enforced by an hourglass-like connectivity pattern, which are just\nlocated at the vertex in the neck of an hourglass and thus called hourglass BCs\n(HBCs), show interesting topological properties and are intimately related with\nthe space group symmetry. Through checking compatibility relations in the\nBrillouin zone (BZ), we list all possible HBCs for all 230 space groups by\nidentifying positions of HBCs as well as the compatibility relations related\nwith the HBCs.The HBCs can be coexisting with conventional topological BCs such\nas Dirac andWeyl fermions and based on our exhaustive list, the dimensionality\nand degeneracy of the HBCs can be quickly identified. It is also found that the\nHBCs can be classified into two categories: one contains essential HBCs which\nare guaranteed to exist, while the HBCs in the other category may be tuned to\ndisappear. Our results can help in efficiently predicting hourglass semimetals\ncombined with first-principles calculations as well as studying transitions\namong various topological crystalline phases."
    },
    {
        "anchor": "Efficient Random Walk Algorithm for Simulating Thermal Transport in\n  Composites With High Conductivity Contrast: In dealing with thermal transport in composite systems, high contrast\nmaterials pose a special problem for numerical simulation: the time scale or\nstep size in the high conductivity material must be much smaller than in the\nlow conductivity material. In the limit that the higher conductivity inclusion\ncan be treated as having an infinite conductivity, we show how a standard\nrandom walk algorithm can be alterred to improve speed while still preserving\nthe second law of thermodynamics. We demonstrate the principle in a 1D system,\nand then apply it to 3D composites with spherical inclusions.",
        "positive": "Polarization enhancement in two- and three-component ferroelectric\n  superlattices: Composition-dependent structural and polar properties of epitaxial\nshort-period CaTiO_3/SrTiO_3/BaTiO_3 superlattices grown on a SrTiO_3 substrate\nare investigated with first-principles density-functional theory computational\ntechniques. Polarization enhancement with respect to bulk tetragonal BaTiO_3 is\nfound for two- and three-component superlattices with a BaTiO_3 concentration\nof more than 30%. Individual BaTiO_3 layer thickness is identified as an\nimportant factor governing the polarization improvement. In addition, the\ndegree of inversion-symmetry breaking in three-component superlattices can be\ncontrolled by varying the thicknesses of the component layers. The flexibility\nallowed within this large family of structures makes them highly suitable for\nvarious applications in modern nano-electro-mechanical devices."
    },
    {
        "anchor": "Electron Paramagnetic Resonance Studies of KYb(MoO4)2: The electron paramagnetic resonance investigations of the magnetically\nconcentrated crystal of KYb(MoO4)2 have been performed. The main value of\ng-factors along principal local axes was determinate. The two nonequivalent\nYb3+ centers were found in ac-plane. It is shown that local symmetry of Yb3+\nion in ac-plane is not higher than rhombic. Some peculiarities in the\nfrequency-field dependence of an absorption line was found in H|| b\norientation.",
        "positive": "{\\it Ab initio} $^{27}Al$ NMR chemical shifts and quadrupolar parameters\n  for $Al_2O_3$ phases and their precursors: The Gauge-Including Projector Augmented Wave (GIPAW) method, within the\nDensity Functional Theory (DFT) Generalized Gradient Approximation (GGA)\nframework, is applied to compute solid state NMR parameters for $^{27}Al$ in\nthe $\\alpha$, $\\theta$, and $\\kappa$ aluminium oxide phases and their gibbsite\nand boehmite precursors. The results for well-established crystalline phases\ncompare very well with available experimental data and provide confidence in\nthe accuracy of the method. For $\\gamma$-alumina, four structural models\nproposed in the literature are discussed in terms of their ability to reproduce\nthe experimental spectra also reported in the literature. Among the considered\nmodels, the $Fd\\bar{3}m$ structure proposed by Paglia {\\it et al.} [Phys. Rev.\nB {\\bf 71}, 224115 (2005)] shows the best agreement. We attempt to link the\ntheoretical NMR parameters to the local geometry. Chemical shifts depend on\ncoordination number but no further correlation is found with geometrical\nparameters. Instead our calculations reveal that, within a given coordination\nnumber, a linear correlation exists between chemical shifts and Born effective\ncharges."
    },
    {
        "anchor": "Infrared spectroscopy of silicon for applications in astronomy: This work focuses on the characterization of various bulk silicon (Si)\nsamples using Fourier Transform InfraRed (FTIR) and grating spectrometers in\norder to get them suitable for applications in astronomy. Different samples at\ndifferent impurity concentrations were characterized by measuring their\ntransmittance in the infrared region. Various lines due to residual impurity\nabsorption were identifed and temperature dependence of impurity absorption is\npresented. Concentrations of doped samples (rho ~ 0.2 - 25000 Ohm cm) were\ndetermined from impurity absorption at low temperatures and from Drude free\ncarrier absorption at 300K.",
        "positive": "A Quantum Chemical Approach to Cohesive Properties of NiO: We apply ab-initio quantum chemical methods to calculate correlation effects\non cohesive properties of NiO, thereby extending a recently proposed scheme to\ntransition metal oxides with partially filled $d$-bands. We obtain good\nagreement with experiment for the cohesive energy and show that the deviation\nof the lattice constant at the Hartree-Fock level is mainly due to van der\nWaals-like interactions. Correlations enhance the stability of the magnetic\nground state found at the Hartree-Fock level."
    },
    {
        "anchor": "A Universal Machine Learning Model for Elemental Grain Boundary Energies: The grain boundary (GB) energy has a profound influence on the grain growth\nand properties of polycrystalline metals. Here, we show that the energy of a\nGB, normalized by the bulk cohesive energy, can be described purely by four\ngeometric features. By machine learning on a large computed database of 361\nsmall $\\Sigma$ ($\\Sigma < 10$) GBs of more than 50 metals, we develop a model\nthat can predict the grain boundary energies to within a mean absolute error of\n0.13 J m$^{-2}$. More importantly, this universal GB energy model can be\nextrapolated to the energies of high $\\Sigma$ GBs without loss in accuracy.\nThese results highlight the importance of capturing fundamental scaling physics\nand domain knowledge in the design of interpretable, extrapolatable machine\nlearning models for materials science.",
        "positive": "Microscopic theory of ionic motion in solid electrolytes: We propose a microscopic, first-principles description of the ionic\nconduction in crystals. This formalism allows us to gain new insights into the\nideal characteristics of general ionic conducting materials and, in particular,\nsolid electrolytes. Using \\textit{ab initio} calculations, we show that our\nformalism results in ionic mobilities consistent with experiments for several\nmaterials. Our work opens the possibility of developing solid electrolytes\nbased on fundamental physical principles rather than empirical descriptions of\nthe underlying processes."
    },
    {
        "anchor": "CO adsorption on Cu(111) and Cu(001) surfaces: improving site preference\n  in DFT calculations: CO adsorption on Cu(111) and Cu(001) surfaces has been studied within\nab-initio density functional theory (DFT). The structural, vibrational and\nthermodynamic properties of the adsorbate-substrate complex have been\ncalculated. Calculations within the generalized gradient approximation (GGA)\npredict adsorption in the threefold hollow on Cu(111) and in the bridge-site on\nCu(001), instead of on-top as found experimentally. It is demonstrated that the\ncorrect site preference is achieved if the underestimation of the HOMO-LUMO gap\nof CO characteristic for DFT is correct by applying a molecular DFT+U approach.\nThe DFT+U approach also produces good agreement with the experimentally\nmeasured adsorption energies, while introducing only small changes in the\ncalculated geometrical and vibrational properties further improving agreement\nwith experiment which is fair already at the GGA level.",
        "positive": "First-principles prediction of lattice coherency in van der Waals\n  heterostructures: The emergence of superconductivity in slightly-misaligned graphene bilayer\n[1] and moir\\'e excitons in MoSe$_2$-WSe$_2$ van der Waals (vdW)\nheterostructures [2] is intimately related to the formation of a 2D\nsuperlattice in those systems. At variance, perfect primitive lattice matching\nof the constituent layers has also been reported in some vdW-heterostructures\n[3-5], highlighting the richness of interfaces in the 2D world. In this work,\nthe determination of the nature of such interface, from first principles, is\ndemonstrated. To do so, an extension of the Frenkel-Kontorova (FK) model [6] is\npresented, linked to first-principles calculations, and used to predict lattice\ncoherency for a set of 56 vdW-heterostructures. Computational predictions agree\nwith experiments, when available. New superlattices as well as\nperfectly-matching interfaces are predicted."
    },
    {
        "anchor": "Atomic models of non-stoichiometric layered diborides M$_{1-x}$B$_2$ (M\n  = Mg, Al, Zr and Nb) from first principles: Two atomic models of non-stoichiometric metal diborides M$_{1-x}$B$_2$ are\nnow assumed: (i) the presence of cation vacancies and (ii) the presence of\n'super-stoichiometric' boron which is placed in cation vacancy site. We have\nperformed first principle total energy calculations using the VASP-PAW method\nwith the generalized gradient approximation (GGA) for the exchange-correlation\npotential in a perspective to reveal the trends of M$_{1-x}$B$_2$ possible\nstable atomic configurations depending on the type of M cations (M = Mg, Al, Zr\nor Nb) and the type of the defects (metal vacancies versus metal vacancies\noccupied by 'super-stoichiometric' boron in forms of single atoms, dimers B$_2$\nor trimers B$_3$). Besides we have estimated the stability of these\nnon-stoichiometric states (on the example of magnesium-boron system) as\ndepending on the possible synthetic routes, namely via solid state reaction\nmethod, as well as in reactions between solid boron and Mg vapor; and between\nthese reagents in gaseous phase. We demonstrate that the non-stoichiometric\nstates such as B$_2$ and B$_3$ placed in metal sites may be stabilized, while\nthe occupation of vacancy sites by single boron atoms is the most unfavorable.",
        "positive": "Predicting the Charge Density Response in Metal Electrodes: The computational study of energy storage and conversion processes calls for\nsimulation techniques that can reproduce the electronic response of metal\nelectrodes under electric fields. Despite recent advancements in\nmachine-learning methods applied to electronic-structure properties, predicting\nthe non-local behavior of the charge density in electronic conductors remains a\nmajor open challenge. We combine long-range and equivariant kernel methods to\npredict the Kohn-Sham electron density of metal electrodes in response to\nvarious kinds of electric field perturbations. By taking slabs of gold as an\nexample, we first show how the non-local electronic polarization generated by\nthe interaction with an ionic species can be accurately reproduced in\nelectrodes of arbitrary thickness. A finite-field extension of the method is\nthen introduced, which allows us to predict the charge transfer and the\nelectrostatic potential drop induced by the application of a homogeneous and\nconstant electric field. Finally, we demonstrate the capability of the method\nto reproduce the charge-density response in a gold/electrolyte capacitor under\nan applied voltage, predicting the system polarization with a greater accuracy\nthan state-of-the-art classical atomic-charge models."
    },
    {
        "anchor": "Alternative structure of TiO2 with higher energy valence band edge: We propose an alternative structure of TiO2 anatase that has a higher energy\noxygen p-like valence band maximum than the pristine TiO2 anatase and thus has\na much better alignment with the water splitting levels. This alternative\nstructure is unique when considering a large subspace of possible structural\ndistortions of TiO2 anatase. We propose two routes towards this state and argue\nthat one of them might have been realized in the recently discovered so-called\nblack TiO2.",
        "positive": "Predicting magnetization of ferromagnetic binary Fe alloys from chemical\n  short range order: Among the ferromagnetic binary alloys, body centered cubic (bcc) Fe-Co is the\none showing the highest magnetization. It is known experimentally that ordered\nFe-Co structures show a larger magnetization than the random solid solutions\nwith the same Co content. In this work, based on density functional theory\n(DFT) studies, we aim at a quantitative prediction of this feature, and point\nout the role of the orbital magnetic moments. Then, we introduce a DFT-based\nanalytical model correlating local magnetic moments and chemical compositions\nfor Co concentrations ranging from 0 to 70 at.%. It is also extended to predict\nthe global magnetization of both ordered and disordered structures at given\nconcentration and chemical short range orders. The latter model is particularly\nuseful for interpreting experimental data. Based on these models, we note that\nthe local magnetic moment of a Fe atom is mainly dictated by the Co\nconcentration in its first two neighbor shells. The detailed local arrangement\nof the Co atoms has a minor effect. These simple models can fully reproduce the\ndifference in magnetization between the ordered and disordered Fe-Co alloys\nbetween 30% and 70% Co, in good agreement with experimental data. Finally, we\nshow that a similar model can be established for another bcc binary Fe alloy,\nthe Fe-Ni, also presenting ferromagnetic interactions between atoms."
    },
    {
        "anchor": "Irreversible Heating Measurement with Microsecond Pulse Magnet: Example\n  of the alpha-theta Phase Transition of Solid Oxygen: Dissipation inevitably occurs in first order phase transitions, leading to\nthe irreversible heating. Conversely, the irreversible heating effect could be\na clue for the first order phase transition. We measured the temperature change\nat the magnetic-field-induced alpha-theta phase transition of solid oxygen. The\nsignificant temperature increase from 13 to 37 K, amounting to 700 J/mol, is\nobserved due to the irreversible heating at the first order phase transition.\nWe argue that the hysteresis loss of the magnetization curve and the\ndissipative structural transformation account for the irreversible heating. The\nmeasurement of the irreversible heating can be utilized for detecting the\nfirst-order phase transition in good combination with the ultrahigh magnetic\nfields generated in microseconds.",
        "positive": "Atomistic Simulations of Basal Dislocations Interacting with\n  Mg$_{17}$Al$_{12}$ Precipitates in Mg: The mechanical properties of Mg-Al alloys are greatly influenced by the\ncomplex intermetallic phase Mg$_{17}$Al$_{12}$, which is the most dominant\nprecipitate found in this alloy system. The interaction of basal edge and\n30$^\\text{o}$ dislocations with Mg$_{17}$Al$_{12}$ precipitates is studied by\nmolecular dynamics and statics simulations, varying the inter-precipitate\nspacing ($L$), and size ($D$), shape and orientation of the precipitates. The\ncritical resolved shear stress $\\tau_c$ to pass an array of precipitates\nfollows the usual $\\ln((1/D + 1/L)^{-1})$ proportionality. In all cases but the\nsmallest precipitate, the dislocations pass the obstacles by depositing\ndislocation segments in the disordered interphase boundary rather than shearing\nthe precipitate or leaving Orowan loops in the matrix around the precipitate.\nAn absorbed dislocation increases the stress necessary for a second dislocation\nto pass the precipitate also by absorbing dislocation segments into the\nboundary. Replacing the precipitate with a void of identical size and shape\ndecreases the critical passing stress and work hardening contribution while an\nartificially impenetrable Mg$_{17}$Al$_{12}$ precipitate increases both. These\ninsights will help improve mesoscale models of hardening by incoherent\nparticles."
    },
    {
        "anchor": "Van der Waals heteroepitaxy of air stable quasi-free standing silicene\n  layers on CVD epitaxial graphene/6H-SiC: Graphene, consisting of an inert, thermally stable material with an\natomically flat, dangling bond-free surface is by essence an ideal template\nlayer for van der Waals heteroepitaxy of two-dimensional materials such as\nsilicene. However, depending on the synthesis method and growth parameters,\ngraphene (Gr) substrates could exhibit, on a single sample, various surface\nstructures, thicknesses, defects, and step heights. These structures noticeably\naffect the growth mode of epitaxial layers, e.g. turning the layer-by-layer\ngrowth into the Volmer-Weber growth promoted by defect-assisted nucleation. In\nthis work, the growth of silicon on chemical vapor deposited epitaxial Gr (1 ML\nGr/1ML Gr buffer) on 6H-SiC(0001) substrate is investigated by a combination of\natomic force microscopy (AFM), scanning tunneling microscopy (STM), x-ray\nphotoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Raman\nspectroscopy measurements. It is shown that the perfect control of full-scale\nalmost defect-free 1 ML Gr with a single surface structure and the ultra-clean\nconditions for molecular beam epitaxy (MBE) deposition of silicon represent key\nprerequisites for ensuring the growth of extended silicene sheets on epitaxial\ngraphene.",
        "positive": "Rippled nanocarbons from periodic arrangements of reordered bivacancies\n  in graphene or SWCNTs: We report on various nanocarbons formed from a unique structural pattern\ncontaining two pentagons, three hexagons and two heptagons, resulting from\nlocal rearrange- ments around a divacancy in pristine graphene or nanotubes.\nThis defect can be inserted in sheets or tubes either individually or as\nextended defect lines. Sheets or tubes containing only this defect as a pattern\ncan also be obtained. These fully defective sheets, and most of the tubes,\npresent a very pronounced rippled (wavy) structure and their energies are lower\nthan other structures based on pentagons and heptagons published so far.\nAnother particularity of these rippled carbon sheets is their ability to fold\nthemselves into a two-dimensional porous network of inter- connected tubes upon\nheat treatment as shown by hybrid Monte Carlo simulations. Finally, contrary to\nthe common belief that pentagon/heptagon based structures are metallic, this\nwork shows that this defect pattern should give rise to semi-metallic\nconduction."
    },
    {
        "anchor": "Carbon phase diagram with empirical and machine learned interatomic\n  potentials: In the present work we detail how the many-body potential energy landscape of\ninteratomic potentials for carbon can be explored by utilising the nested\nsampling algorithm, allowing the calculation of their pressure-temperature\nphase diagram up to high pressures. We present a comparison of three\ninteratomic potential models, Tersoff, EDIP and GAP-20, focusing on their\nmacroscopic properties, particularly on their melting transition and on\nidentifying thermodynamically stable solid structures up to at least 100 GPa.\nThe studied models all form graphite structures upon freezing at lower\npressure, then the diamond structure as the pressure increases. We were able to\nlocate the transition between these phases in case of the Tersoff and EDIP\nmodels. We placed particular focus on the state-of-the-art machine learning\n(ML) model, GAP-20, and calculated its phase diagram up to 1 TPa to evaluate\nits predictive capabilities well outside of the model's fitting conditions. The\nphase diagram showed a remarkably good agreement with the experimental phase\ndiagram up to 200 GPa, despite a variety of unexpected graphite layer spacing.\nAbove that nested sampling identified two novel stable solid structures, a\nstrained diamond structure and above 800 GPa a strained hexagonal-close-packed\nstructure. However, the stability of these two phases were not confirmed by DFT\ncalculations, highlighting potential routes to further improve the ML model.",
        "positive": "Crystal orientation-dependent oxidation of epitaxial TiN films with\n  tunable plasmonics: Titanium nitride (TiN) is a paradigm of refractory transition metal nitrides\nwith great potential in vast applications. Generally, the plasmonic performance\nof TiN can be tuned by oxidation, which was thought to be only temperature-,\noxygen partial pressure-, and time-dependent. Regarding the role of\ncrystallographic orientation in the oxidation and resultant optical properties\nof TiN films, little is known thus far. Here we reveal that both the oxidation\nresistance behavior and the plasmonic performance of epitaxial TiN films follow\nthe order of (001) < (110) < (111). The effects of crystallographic orientation\non the lattice constants, optical properties, and oxidation levels of epitaxial\nTiN films have been systematically studied by combined high-resolution X-ray\ndiffraction, spectroscopic ellipsometry, X-ray absorption spectroscopy, and\nX-ray photoemission spectroscopy. To further understand the role of\ncrystallographic orientation in the initial oxidation process of TiN films,\ndensity-functional-theory calculations are carried out, indicating the energy\ncost of oxidation is (001) < (110) < (111), consistent with the experiments.\nThe superior endurance of the (111) orientation against mild oxidation can\nlargely alleviate the previously stringent technical requirements for the\ngrowth of TiN films with high plasmonic performance. The crystallographic\norientation can also offer an effective controlling parameter to design\nTiN-based plasmonic devices with desired peculiarity, e.g., superior chemical\nstability against mild oxidation or large optical tunability upon oxidation."
    },
    {
        "anchor": "On the competition between dislocation transmission and crack nucleation\n  at phase boundaries: The interaction of dislocations with phase boundaries is a complex\nphenomenon, that is far from being fully understood. A 2D Peierls-Nabarro\nfinite element (PN-FE) model for studying edge dislocation transmission across\nfully coherent and non-damaging phase boundaries was recently proposed. This\npaper brings a new dimension to the complexity by extending the PN-FE model\nwith a dedicated cohesive zone model for the phase boundary. With the proposed\nmodel, a natural interplay between dislocations, external boundaries and the\nphase boundary, including decohesion of that boundary, is provided. It allows\none to study the competition between dislocation transmission and phase\nboundary decohesion. Commonly, the interface potentials required for glide\nplane behaviour and phase boundary decohesion are established through atomistic\nsimulations. They are corresponding to the misfit energy intrinsic to a system\nof two bulks of atoms that are translated rigidly with respect to each other.\nIt is shown that the blind utilisation of these potentials in zero-thickness\ninterfaces (as used in the proposed model) may lead to a large quantitative\nerror. Accordingly, for physical consistency, the potentials need to be reduced\ntowards zero-thickness potentials. In this paper a linear elastic reduction is\nadopted. With the reduced potentials for the glide plane and the phase\nboundary, the competition between dislocation transmission and phase boundary\ndecohesion is studied for an 8-dislocation pile-up system. Results reveal a\nstrong influence of the phase contrast in material properties as well as the\nphase boundary toughness on the outcome of this competition. In the case of\ncrack nucleation, the crack length shows an equally strong dependency on these\nproperties.",
        "positive": "Sealing is at the Origin of Rubber Slipping on Wet Roads: Loss of braking power and rubber skidding on a wet road is still an open\nphysics problem, since neither the hydrodynamical effects nor the loss of\nsurface adhesion that are sometimes blamed really manage to explain the 20-30%\nobserved loss of low speed tire-road friction. Here we advance a novel\nmechanism based on sealing of water-filled substrate pools by the rubber. The\nsealed-in water effectively smoothens the substrate, thus reducing the\nviscoelastic dissipation in bulk rubber induced by surface asperities, well\nestablished as a major friction contribution. Starting with the measured\nspectrum of asperities one can calculate the water-smoothened spectrum and from\nthat the predicted friction reduction, which is of the right magnitude. The\ntheory is directly supported by fresh tire-asphalt friction data."
    },
    {
        "anchor": "X-ray absorption spectroscopy of oligothiophene crystals from many-body\n  perturbation theory: We present an x-ray absorption spectroscopy study from the carbon $K$, sulfur\n$K$, and sulfur $L_{2,3}$ edges of crystalline oligothiophenes of varying\nlength, i.e., bithiophene (2T), quaterthiophene (4T), and sexithiophene (6T),\nperformed from first principles by means of all-electron density-functional\ntheory and many-body perturbation theory. A comprehensive assignment of all\nrelevant spectral features is performed based on the electronic structure and\nthe character of the target conduction states. The inclusion of electron-hole\neffects leads to significant redistribution of oscillator strengths and to\nstrongly bound excitons with binding energies ranging from 1.5 to 4.5 eV. When\ngoing from 2T to 6T, exciton binding energies decrease by up to 1 eV, which we\nattribute to the reduction of the average Coulomb attraction with increasing\noligomer length. These high values are significantly larger than their\ncounterparts in the optical excitations of these systems and indicative of\ntheir localization on the respective molecules. For the same reason,\nlocal-field effects which typically dominate the optical absorption of organic\ncrystals, turn out to play only a negligible role at all edges. We identify two\nsets of carbon atoms, i.e., with or without sulfur bonding, which exhibit\ndistinct features at the C $K$-edge. The sulfur atoms, on the other hand, yield\nsimilar contributions in the S, $K$, and $L_{2,3}$ edge spectra. Our results\nshow excellent agreement with available experimental data.",
        "positive": "Surface Piezoelectricity of (0001) Sapphire: Interfaces of sapphire are of technological relevance as sapphire is used as\na substrate in electronics, lasers, and Josephson junctions for quantum\ndevices. In addition, its surface is potentially useful in catalysis. Using\nfirst principles calculations, we show that, unlike bulk sapphire which has\ninversion symmetry, the (0001) sapphire surface is piezoelectric. The inherent\nbroken symmetry at the surface leads to a surface dipole and a significant\nresponse to imposed strain: the magnitude of the surface piezoelectricity is\ncomparable to that of bulk piezoelectrics."
    },
    {
        "anchor": "Ferrimagnetism in the Spin-1/2 Heisenberg Antiferromagnet on a Distorted\n  Triangular Lattice: The ground state of the spin-$1/2$ Heisenberg antiferromagnet on a distorted\ntriangular lattice is studied using a numerical-diagonalization method. The\nnetwork of interactions is the $\\sqrt{3}\\times\\sqrt{3}$ type; the interactions\nare continuously controlled between the undistorted triangular lattice and the\ndice lattice. We find new states between the nonmagnetic 120-degree-structured\nstate of the undistorted triangular case and the up-up-down state of the dice\ncase. The intermediate states show spontaneous magnetizations that are smaller\nthan one third of the saturated magntization corresponding to the up-up-down\nstate.",
        "positive": "Fluctuations in a model ferromagnetic film driven by a slowly\n  oscillating field with a constant bias: We present a numerical and theoretical study that supports and explains\nrecent experimental results on anomalous magnetization fluctuations of a\nuniaxial ferromagnetic film in its low-temperature phase, which is forced by an\noscillating field above the critical period of the associated dynamic phase\ntransition (DPT) [P. Riego, P. Vavassori, A. Berger, Phys. Rev. Lett. 118,\n117202 (2017)]. For this purpose, we perform kinetic Monte Carlo simulations of\na two-dimensional Ising model with nearest-neighbor ferromagnetic interactions\nin the presence of a sinusoidally oscillating field, to which is added a\nconstant bias field. We study a large range of system sizes and supercritical\nperiods and analyze the data using a droplet-theoretical description of\nmagnetization switching. We find that the period-averaged magnetization, which\nplays the role of the order parameter for the DPT, presents large fluctuations\nthat give rise to well-defined peaks in its scaled variance and its\nsusceptibility with respect to the bias field. The peaks are symmetric with\nrespect to zero bias and located at values of the bias field that increase\ntoward the field amplitude as an inverse logarithm of the field oscillation\nperiod. Our results indicate that this effect is independent of the system size\nfor large systems, ruling out critical behavior associated with a phase\ntransition. Rather, it is a stochastic-resonance phenomenon that has no\ncounterpart in the corresponding thermodynamic phase transition, providing a\nreminder that the equivalence of the DPT to an equilibrium phase transition is\nlimited to the critical region near the critical period and zero bias."
    },
    {
        "anchor": "Predicting the location of shear band initiation in a metallic glass: We report atomistic simulation results which indicate that the location of\nshear banding in a metallic glass (MG) can be ascertained with reasonably high\naccuracy solely from the undeformed static structure. Correlation is observed\nbetween the location of the initiation of shear bands in a simulated MG and the\ninitial distribution of the density of fertile sites (DFS) for stress-driven\nshear transformations identified a priori based on a deep learning model\ndevised in our recent work [Fan and Ma, Nat. Commun. 12, 1506 (2021)]. In\naddition, we demonstrated that one can judge whether a glass is brittle or\nductile solely based upon its initial DFS distribution. These validate that\nshear bands in MG arise from non-linear instabilities, and that the as-quenched\nglass structure contains inhomogeneities that influence these instabilities.\nThis work also reveals an important subtlety regarding the non-deterministic\nnature of athermal quasistatic shear simulations.",
        "positive": "Assessing the SCAN functional for itinerant electron ferromagnets: Density functional theory is a standard model for condensed matter theory and\ncomputational material science. The accuracy of density functional theory is\nlimited by accuracy of the employed approximation to the exchange-correlation\nfunctional. Recently, the so-called strongly constrained approprietly normed\n(SCAN) functional has received a lot of attention due to promising results for\ncovalent, metallic, ionic, as well as hydrogen- and van der Waals-bonded\nsystems alike. In this work we focus on assessing the performance of the SCAN\nfunctional for itinerant magnets by calculating basic structural and magnetic\nproperties of the transition metals Fe, Co and Ni. We find that although\nstructural properties of bcc-Fe seem to be in good agreement with experiment,\nSCAN performs worse than standard local and semilocal functionals for fcc-Ni\nand hcp-Co. In all three cases, the magnetic moment is significantly\noverestimated by SCAN, and the $3d$ states are shifted to lower energies, as\ncompared to experiments."
    },
    {
        "anchor": "Recent advances on thermoelectric materials: By converting waste heat into electricity through the thermoelectric power of\nsolids without producing greenhouse gas emissions, thermoelectric generators\ncould be an important part of the solution to today's energy challenge. There\nhas been a resurgence in the search for new materials for advanced\nthermoelectric energy conversion applications. In this paper, we will review\nrecent efforts on improving thermoelectric efficiency. Particularly, several\nnovel proof-of-principle approaches such as phonon disorder in\nphonon-glasselectron crystals, low dimensionality in nanostructured materials\nand charge-spin-orbital degeneracy in strongly correlated systems on\nthermoelectric performance will be discussed.",
        "positive": "Observation of spin-momentum-layer locking in centrosymmetric BiOI: Spin polarization effects in nonmagnetic materials are generally believed as\nan outcome of spin-orbit coupling provided that the global inversion symmetry\nis lacking, also known as 'spin-momentum locking'. The recently discovered\nhidden spin polarization indicates that specific atomic site asymmetry could\nalso induce measurable spin polarization, leading to a paradigm shift to\ncentrosymmetric crystals for potential spintronic applications. Here, combining\nspin- and angle-resolved photoemission spectroscopy and theoretical\ncalculations, we report distinct spin-layer locking phenomena surrounding\ndifferent high-symmetry momenta in a centrosymmetric, layered material BiOI.\nThe measured spin is highly polarized along the Brillouin zone boundary, while\nis almost vanishing around the zone center due to its nonsymmorphic crystal\nstructure. Our work not only demonstrates the existence of hidden spin\npolarization, but also uncovers the microscopic mechanism of the way spin,\nmomentum and layer locking to each other, shedding lights on the design metrics\nfor future spintronic devices."
    },
    {
        "anchor": "Ab-initio study of structure and dynamics properties of crystalline ice: We investigated the structural and dynamical properties of a tetrahedrally\ncoordinated crystalline ice from first principles based on density functional\ntheory within the generalized gradient approximation with the projected\naugmented wave method. First, we report the structural behaviour of ice at\nfinite temperatures based on the analysis of radial distribution functions\nobtained by molecular dynamics simulations. The results show how the ordering\nof the hydrogen bonding breaks down in the tetrahedral network of ice with\nentropy increase in agreement with the neutron diffraction data. We also\ncalculated the phonon spectra of ice in a 3x1x1 supercell by using the direct\nmethod. So far, due to the direct method used in this calculation, the phonon\nspectra is obtained without taking into account the effect of polarization\narising from dipole-dipole interactions of water molecules which is expected to\nyield the splitting of longitudinal and transverse optic modes at the\nGamma-point. The calculated longitudinal acoustic velocities from the initial\nslopes of the acoustic mode is in a reasonable agreement with the neutron\nscatering data. The analysis of the vibrational density of states shows the\nexistence of a boson peak at low energy of translational region a\ncharacteristic common to amorphous systems.",
        "positive": "Enhanced Ferromagnetism in Monolayer Cr2Te3 via Topological Insulator\n  Coupling: Exchange-coupled interfaces are pivotal in exploiting two-dimensional (2D)\nferromagnetism. Due to the extraordinary correlations among charge, spin,\norbital and lattice degrees of freedom, layered magnetic transition metal\nchalcogenides (TMCs) bode well for exotic topological phenomena. Here we report\nthe realization of wafer-scale Cr2Te3 down to monolayer (ML) on insulating\nSrTiO3(111) substrates using molecular beam epitaxy. Robust ferromagnetism\nemerges in 2D Cr2Te3 ML with a Curie temperature TC = 17 K. Moreover, when\nCr2Te3 is proximitized with topological insulator (TI) (Bi,Sb)2Te3, the\nmagnetism becomes stronger -- for 1 ML, TC increases to 30 K, while for 2 ML it\nboosts from 65 K to 82 K. Our experiments and theory strongly indicate that the\nBloembergen-Rowland interaction is likely a universal aspect of TC enhancement\nin TI-coupled magnetic heterostructures. The topological-surface-enhanced\nmagnetism in 2D TMC enables further exchange coupling physics and quantum\nhybrid studies, including paving the way to realize interface-modulated\ntopological electronics."
    },
    {
        "anchor": "Band offset of GaAs/AlxGa1-xAs heterojunctions from atomistic first\n  principles: Using an atomistic first principles approach, we investigate the band offset\nof the GaAs/AlxGa1-xAs heterojunctions for the entire range of the Al doping\nconcentration 0<x<=1. We apply the coherent potential approach to handle the\nconfiguration average of Al doping and a recently proposed semi-local exchange\npotential to accurately determine the band gaps of the materials. The\ncalculated band structures of the GaAs, AlAs crystals and band gaps of the\nGaAs/AlxGa1-xAs alloys, are in very good agreement with the experimental\nresults. We predict that valence band offset of the GaAs/AlxGa1-xAs\nheterojunction scales with the Al concentration x in a linear fashion as\nVBO(x)~0.587 x, and the conduction band offset scales with x in a nonlinear\nfashion. Quantitative comparisons to the corresponding experimental data are\nmade.",
        "positive": "Magnetization dynamics down to zero field in dilute (Cd,Mn)Te quantum\n  wells: The evolution of the magnetization in (Cd,Mn)Te quantum wells after a short\npulse of magnetic field was determined from the giant Zeeman shift of\nspectroscopic lines. The dynamics in absence of magnetic field was found to be\nup to three orders of magnitude faster than that at 1 T. Hyperfine interaction\nand strain are mainly responsible for the fast decay. The influence of a hole\ngas is clearly visible: at zero field anisotropic holes stabilize the system of\nMn ions, while in a magnetic field of 1 T they are known to speed up the decay\nby opening an additional relaxation channel."
    },
    {
        "anchor": "Mobility Transition at Grain Boundaries in Two-Step Sintered 8 mol%\n  Yttria Stabilized Zirconia: Stagnation of grain growth is often attributed to impurity segregation.\nYttria-stabilized cubic zirconia does not evidence any segregation-induced\nslowdown, as its grain growth obeys the parabolic law when the grain size\nincreases by more than one order of magnitude. However, lowering the\ntemperature below 1300 oC triggers an abrupt slowdown, constraining the average\ngrains to grow by less than 0.5 ${\\mu}$m in 1000 h despite a relatively large\ndriving force imparted in the fine grains of ~0.5 ${\\mu}$m. Yet isolated\npockets of abnormally large grains, along with pockets of abnormally small\ngrains, emerge in the same latter sample. Such microstructure bifurcation has\nnever been observed before, and can only be explained by an inhomogeneous\ndistribution of immobile four-grain junctions. The implications of these\nfindings for two-step sintering are discussed.",
        "positive": "Electronic Structure of Ta$_2$O$_5$ Polymorphs: Variation Trend of Band\n  Gap and the Role of Oxygen Vacancies: We provide a systematic study on the electronic structure of a series of\nTa$_2$O$_5$ polymorphs using standard density functional theory (DFT)\ncalculations as well as the more accurate many-body perturbation theory within\nthe GW approximation. For the defect-free polymorphs, the variation trend of\nband gap can be microscopically related to the strength of orbital\nhybridization, and to the macroscopic bulk formation energy. The presence of\noxygen vacancies is found to have profound effects on the electronic properties\nnear the Fermi level, notably the reduction of band gap and gap closure\n(insulator-to-metal transition). Furthermore, depending on the vacancy sites,\nthe band gap of some defective system may be enlarged with comparison to its\ndefect-free counterpart. Such an anomalous behavior originates from the\nunexpected formation of Ta-Ta bonds."
    },
    {
        "anchor": "Topological crystalline insulator states in the Ca$_2$As family: Topological crystalline insulators (TCI) are insulating electronic phases of\nmatter with nontrivial topology originating from crystalline symmetries. Recent\ntheoretical advances have provided powerful guidelines to search for TCIs in\nreal materials. Using density functional theory, we identify a class of new TCI\nstates in the tetragonal lattice of the Ca$_2$As material family. On both top\nand side surfaces, we observe topological surface states protected\nindependently by rotational and mirror symmetries. We show that a particular\nlattice distortion can single out the newly proposed topological protection by\nthe rotational symmetry. As a result, the Dirac points of the topological\nsurface states are moved to generic locations in momentum space away from any\nhigh symmetry lines. Such topological surface states have not been seen before.\nMoreover, the other family members, including Ca$_2$Sb, Ca$_2$Bi and Sr$_2$Sb,\nfeature different topological surface states due to their distinct topological\ninvariants. We thus further propose topological phase transitions in the\npseudo-binary systems such as (Ca$_{1-x}$Sr$_x$)$_2$As and\nCa$_2$As$_x$Sb$_{1-x}$. Our work reveals rich and exotic TCI physics across the\nCa$_2$As family of materials, and suggests the feasibility of materials\ndatabase search methods to discover new TCIs.",
        "positive": "Guidelines for understanding cubic manganese-rich Heusler compounds: Manganese-rich Heusler compounds are attracting much interest in the context\nof spin transfer torque and rare-earth free hard magnets. Here we give a\ncomprehensive overview of the magnetic properties of non-centrosymmetric cubic\nMn$_2$-based Heusler materials, which are characterized by an antiparallel\ncoupling of magnetic moments on Mn atoms. Such a ferrimagnetic order leads to\nthe emergence of new properties that are absent in ferromagnetic\ncentrosymmetric Heusler structures. In terms of the band structure\ncalculations, we explain the formation of this magnetic order and the Curie\ntemperatures. This overview is intended to establish guidelines for a basic\nunderstanding of magnetism in Mn2 -based Heusler compounds."
    },
    {
        "anchor": "Formation of Vacancies in Si- and Ge-based Clathrates: Role of Electron\n  Localization and Symmetry Breaking: The formation of framework vacancies in Si- and Ge-based type-I clathrates is\nstudied as function of filling the cages with K and Ba atoms using\ndensity-functional theory. Our analysis reveals the relevance of structural\ndisorder, geometric relaxation, electronic saturation, as well as vibrational\nand configurational entropy. In the Si clathrates we find that vacancies are\nunstable, but very differently, in Ge clathrates up to three vacancies per unit\ncell can be stabilized. This contrasting behavior is largely driven by the\ndifferent energy gain on populating the electronic vacancy states, which\noriginates from the different degree of localization of the valence orbitals of\nSi and Ge. This also actuates a qualitatively different atomic relaxation of\nthe framework.",
        "positive": "Intersublattice magnetocrystalline anisotropy using a realistic\n  tight-binding method based on maximally localized Wannier functions: Using a realistic tight-binding Hamiltonian based on maximally localized\nWannier functions, we investigate the two-ion magnetocrystalline anisotropy\nenergy (MAE) in $L1_0$ transition metal compounds. MAE contributions from\nthroughout the Brillouin zone are obtained using magnetic force theorem\ncalculations with and without perturbation theory. The results from either\nmethod agree with one another, and both reflect features of the Fermi surface.\nThe intra-sublattice and inter-sublattice contributions to MAE are evaluated\nusing a Green's function method. We find that the sign of the inter-sublattice\ncontribution varies among compounds, and that its amplitude may be significant,\nsuggesting MAE can not be resolved accurately in a single-ion manner. The\nresults are further validated by scaling spin-orbit-coupling strength in\ndensity functional theory. Overall, this realistic tight-binding method provide\nan effective approach to evaluate and analyze MAE while retaining the accuracy\nof corresponding first-principles methods."
    },
    {
        "anchor": "Grain boundary energies and cohesive strength as a function of geometry: Cohesive laws are stress-strain curves used in finite element calculations to\ndescribe the debonding of interfaces such as grain boundaries. It would be\nconvenient to describe grain boundary cohesive laws as a function of the\nparameters needed to describe the grain boundary geometry; two parameters in 2D\nand 5 parameters in 3D. However, we find that the cohesive law is not a smooth\nfunction of these parameters. In fact, it is discontinuous at geometries for\nwhich the two grains have repeat distances that are rational with respect to\none another. Using atomistic simulations, we extract grain boundary energies\nand cohesive laws of grain boundary fracture in 2D with a Lennard-Jones\npotential for all possible geometries which can be simulated within periodic\nboundary conditions with a maximum box size. We introduce a model where grain\nboundaries are represented as high symmetry boundaries decorated by extra\ndislocations. Using it, we develop a functional form for the symmetric grain\nboundary energies, which have cusps at all high symmetry angles. We also find\nthe asymptotic form of the fracture toughness near the discontinuities at high\nsymmetry grain boundaries using our dislocation decoration model.",
        "positive": "Free energy and molecular dynamics calculations for the cubic-tetragonal\n  phase transition in zirconia: The high-temperature cubic-tetragonal phase transition of pure stoichiometric\nzirconia is studied by molecular dynamics (MD) simulations and within the\nframework of the Landau theory of phase transformations. The interatomic forces\nare calculated using an empirical, self-consistent, orthogonal tight-binding\n(SC-TB) model, which includes atomic polarizabilities up to the quadrupolar\nlevel. A first set of standard MD calculations shows that, on increasing\ntemperature, one particular vibrational frequency softens. The temperature\nevolution of the free energy surfaces around the phase transition is then\nstudied with a second set of calculations. These combine the thermodynamic\nintegration technique with constrained MD simulations. The results seem to\nsupport the thesis of a second-order phase transition but with unusual, very\nanharmonic behaviour above the transition temperature."
    },
    {
        "anchor": "Fe and N self-diffusion in amorphous FeN: A SIMS and neutron\n  reflectivity study: Simultaneous measurement of self-diffusion of iron and nitrogen in amorphous\niron nitride (Fe86N14) using secondary ion mass spectroscopy (SIMS) technique\nhas been done. In addition neutron reflectivity (NR) technique was employed to\nstudy the Fe diffusion in the same compound. The broadening of a tracer layer\nof 57Fe8615N14 sandwiched between Fe86N14 layers was observed after isothermal\nvacuum annealing of the films at different temperatures in SIMS measurements.\nAnd a decay of the Bragg peak intensity after isothermal annealing was observed\nin [Fe86N14/57Fe86N14]10 multilayers in NR. Strong structural relaxation of\ndiffusion coefficient was observed below the crystallization temperature of the\namorphous phase in both measurements. It was observed from the SIMS\nmeasurements that Fe diffusion was about 2 orders of magnitude smaller compared\nto nitrogen at a given temperature. The NR measurements reveal that the\nmechanism of Fe self-diffusion is very similar to that in metal-metal type\nmetallic glasses. The structural relaxation time for Fe and N diffusion was\nfound comparable indicating that the obtained relaxation time essentially\npertain to the structural relaxation of the amorphous phase.",
        "positive": "Co-operative Influence of O2 and H2O in the Degradation of Layered Black\n  Arsenic: Layered black arsenic (b-As) has recently emerged as a new anisotropic\ntwo-dimensional (2D) semiconducting material with applications in electronic\ndevices. Understanding factors affecting the ambient stability of this material\nremains crucial for its applications. Herein we use first-principles density\nfunctional theory (DFT) calculations to examine the stability of the (010) and\n(101) surfaces of b-As in the presence of oxygen (O2) and water (H2O). We show\nthat the (101) surface of b-As can easily oxidize in presence of O2. In the\npresence of moisture contained in air, the oxidized b-As surfaces favorably\nreact with H2O molecules to volatilize As in the form of As(OH)3 and AsO(OH),\nwhich results in the degradation of the b-As surface, predominantly across the\n(101) surface. These predictions are in good agreement with experimental\nelectron microscopy observations, thus demonstrating the co-operative\nreactivity of O2 and H2O in the degradation of layered b-As under ambient\nconditions."
    },
    {
        "anchor": "Theoretical derivation of the bi- and tri-molecular trion formation\n  coefficients: A theoretical investigation of the trion formation process from free carriers\nin a single GaAs/Al_{1-x}Ga_{x}As quantum well is presented. The mechanism for\nthe formation process is provided by the interaction of the electrons and holes\nwith phonons. The contributions from both the acoustic and optical phonons are\nconsidered. The dependence of both bi-molecular and tri-molecular formation\nrates on temperature is calculated. We demonstrate that they are equivalent for\nnegatively and positively charged excitons.",
        "positive": "Morphology and photocatalytic activity of highly oriented mixed phase\n  titanium dioxide thin films: Thin TiO2 films on quartz substrates were prepared by spin coating of undoped\nand metal-ion-doped Sol Gel precursors. These films were characterised by\nScanning Electron Microscopy, Laser Raman Microspectroscopy, Xray Diffraction\nand UV Vis Transmission. The photocatalytic performances of the films were\nassessed by the photo-degradation of methylene-blue in aqueous solution under\nUV irradiation. Films exhibited a high degree of orientation and a thermal\nstabilization of the anatase phase as a result of substrate effects. In the\nabsence of dopants, the rutile phase formed as parallel bands in the anatase\nwhich broadened as the transformation progressed. TiO2 films doped or co-doped\nwith transition metals exhibited the formation of rutile in segregated clusters\nat temperatures under 800C as a result of increased levels of oxygen vacancies.\nPhotocatalytic activity of the films synthesised in this work was low as likely\na result of poor TiO2 surface contact with dye molecules in the solution. The\npresence of transition metal dopants appears detrimental to photocatalytic\nactivity while the performance of mixed phase films was not observed to differ\nsignificantly from single phase material."
    },
    {
        "anchor": "Discovery and Engineering of Low Work Function Perovskite Materials: Materials with low work functions are critical for an array of applications\nrequiring the facile removal or efficient transport of electrons through a\ndevice. Perovskite oxides are a promising class of materials for finding low\nwork functions, and here we target applications in thermionic and field\nelectron emission. Perovskites have highly malleable compositions which enable\ntunable work function values over a wide range, robust stability at high\ntemperatures, and high electronic conductivities. In this work, we screened\nover 2900 perovskite oxides in search of stable, conductive, low-work-function\nmaterials using Density Functional Theory (DFT) methods. Our work provides\ninsight into the materials chemistry governing the work function value of a\nperovskite, where materials with barely filled d bands possess the lowest work\nfunctions. Our screening has resulted in a total of seven promising compounds,\nsuch as BaMoO3 and SrNb0.75Co0.25O3 with work functions of 1.1 eV and 1.5 eV,\nrespectively. These promising materials and others presented in this study may\nfind use as low work function electron emitters in high power vacuum electronic\nand thermionic energy conversion devices. Moreover, the database of calculated\nwork functions and materials chemistry trends governing the value of the work\nfunction may aid in the engineering of perovskite heterojunction devices.",
        "positive": "Transforming 2D carbon allotropes into 3D ones through topological\n  mapping: The case of biphenylene carbon (graphenylene): In this work, we propose a new methodology for obtaining 3D carbon allotrope\nstructures from 2D ones through topological mapping. The idea is to select a 3D\ntarget structure and 'slice' it along different structural directions, creating\na series of 2D structures. As a proof of concept, we chose the Tubulane\nstructure 12-hexa(3,3) as a target. Tubulanes are 3D carbon allotropes based on\ncross-linked carbon nanotubes. One of obtained 2D 'sliced' structures was\nmapped into the biphenylene carbon (BPC). We showed that compressing BPC along\ndifferent directions can generate not only the target Tubulane 12-hexa(3,3) but\nat least two other structures, bcc-C6 and an unreported member of the Tubulane\nfamily, which we called Tubulane X. The methodology proposed here is completely\ngeneral, it can be used coupled with any quantum method. Considering that new\n2D carbon allotropes, such as the biphenylene carbon network, which is closely\nrelated to BPC, have been recently synthesized, the approach proposed here\nopens new perspectives to obtain new 3D carbon allotropes from 2D structures."
    },
    {
        "anchor": "Measurements of thermodynamic and transport properties of EuC$_2$: a\n  low-temperature analogue of EuO: EuC$_2$ is a ferromagnet with a Curie-temperature of $T_C \\simeq 15\\,$K. It\nis semiconducting with the particularity that the resistivity drops by about 5\norders of magnitude on cooling through $T_C$, which is therefore called a\nmetal-insulator transition. In this paper we study the magnetization, specific\nheat, thermal expansion, and the resistivity around this ferromagnetic\ntransition on high-quality EuC$_2$ samples. At $T_C$ we observe well defined\nanomalies in the specific heat $c_p(T)$ and thermal expansion $\\alpha(T)$ data.\nThe magnetic contributions of $c_p(T)$ and $\\alpha(T)$ can satisfactorily be\ndescribed within a mean-field theory, taking into account the magnetization\ndata. In zero magnetic field the magnetic contributions of the specific heat\nand thermal expansion fulfill a Gr\\\"uneisen-scaling, which is not preserved in\nfinite fields. From an estimation of the pressure dependence of $T_C$ via\nEhrenfest's relation, we expect a considerable increase of $T_C$ under applied\npressure due to a strong spin-lattice coupling. Furthermore the influence of\nweak off stoichiometries $\\delta$ in EuC$_{2 \\pm \\delta}$ was studied. It is\nfound that $\\delta$ strongly affects the resistivity, but hardly changes the\ntransition temperature. In all these aspects, the behavior of EuC$_2$ strongly\nresembles that of EuO.",
        "positive": "Short-range exchange-correlation energy of a uniform electron gas with\n  modified electron-electron interaction: We calculate the short-range exchange-correlation energy of the uniform\nelectron gas with two modified electron-electron interactions. While the\nshort-range exchange functionals are calculated analytically, Coupled-Cluster\nand Fermi-hypernetted chain calculations are carried out for the correlation\nenergy and the results are fitted to an analytical parametrization. These data\nenable to construct the local density approximation corresponding to these\nmodified interactions."
    },
    {
        "anchor": "Modeling Molecular Magnets with Large Exchange and On-Site Anisotropies: Spins in molecular magnets can experience both anisotropic exchange\ninteractions and on-site magnetic anisotropy. In this paper we study the effect\nof exchange anisotropy on the molecular magnetic anisotropy both with and\nwithout on-site anisotropy. When both the anisotropies are small, we find that\nthe axial anisotropy parameter $D_M$ in the effective spin Hamiltonian is the\nsum of the individual contributions due to exchange and on-site anisotropies.\nWe find that even for axial anisotropy of about $15\\%$, the low energy spectrum\ndoes not correspond to a single parent spin manifold but has intruders states\narising from other parent spin. In this case, the low energy spectrum can not\nbe described by an effective Hamiltonian spanning the parent spin space. We\nstudy the magnetic susceptibility, specific heat as a function of temperature\nand magnetization as a function of applied field to characterize the system in\nthis limit. We find that there is synergy between the two anisotropies,\nparticularly for large systems with higher site spins.",
        "positive": "Do uniform tangential interfacial stresses affect adhesion?: We present theoretical arguments, based on linear elasticity and\nthermodynamics, to show that interfacial tangential stresses in sliding\nadhesive contacts does not affet at all the adhesive behavior of the system,\nwhich then follows the classical JKR solution. Our finding explains the\nexperimental observation of Vorvolakos and Chaudhury in 2003, who found that\nthe contact area of a PDMS sphere remains constant during sliding and is in\nagreement with the JKR solution, at least up to velocity of 1mm/s, and of\nCarpick et al. Carpick, who observed that the friction force between a\nplatinum-coated atomic force microscope (AFM) tip and the surface of mica in\nultrahigh vacuum (UHV) varies with load in proportion to the contact area\npredicted by the Johnson-Kendall-Roberts (JKR). We show that a reduction of the\ncontact area, experimentlly observed at higher sliding speeds, can be caused by\na reduction of the density of adhesive bonds as the velocity is increased, or\ncaused by the repulsive energy term associated with the stress spatial\nfluctuation at the interface. This may explain why adhesion is completely\nmasked at relatively large sliding velocities.\n  This version of the paper follows the publication of the Corrigendum: Nicola\nMenga, Giuseppe Carbone, Daniele Dini: Corrigendum to \"Do uniform tangential\ninterfacial stresses enhance adhesion?\" [Journal of the Mechanics and Physics\nof Solids 112 (2018) 145--156], Journal of the Mechanics and Physics of Solids,\n133, 103744, https://doi.org/10.1016/j.jmps.2019.103744, available on line\nsince 8 October 2019."
    },
    {
        "anchor": "Insight into the structural and magnetotransport properties of epitaxial\n  heterostructures $\u03b1$-Fe$_2$O$_3$-Pt(111): Role of the reversed layer\n  sequence: We report on the chemical structure and spin Hall magnetoresistance (SMR) in\nepitaxial $\\alpha$-Fe$_2$O$_3$(hematite)(0001)/Pt(111) bilayers with hematite\nthicknesses of 6 nm and 15 nm grown by molecular beam epitaxy on a MgO(111)\nsubstrate. Unlike previous studies that involved Pt overlayers on hematite, the\npresent hematite films were grown on a stable Pt buffer layer and displayed\nstructural changes as a function of thickness. These structural differences\n(the presence of a ferrimagnetic phase in the thinner film) significantly\naffected the magnetotransport properties of the bilayers. We observed a sign\nchange of the SMR from positive to negative when the thickness of hematite\nincreased from 6 nm to 15 nm. For $\\alpha$-Fe$_2$O$_3$(15 nm)/Pt, we\ndemonstrated room-temperature switching of the N\\'eel order with rectangular,\nnondecaying switching characteristics. Such structures open the way to\nextending magnetotransport studies to more complex systems with double\nasymmetric metal/hematite/Pt interfaces.",
        "positive": "A High-Throughput Computational Dataset of Halide Perovskite Alloys: Novel halide perovskites with improved stability and optoelectronic\nproperties can be designed via composition engineering at cation and/or anion\nsites. Data-driven methods, especially high-throughput first principles\ncomputations and subsequent analysis based on unique materials descriptors, are\nkey to achieving this goal. In this work, we report a density functional theory\n(DFT) based dataset of 495 $ABX_3$ halide perovskite compounds, with various\natomic and molecular species considered at A, B and X sites, and different\namounts of mixing applied at each site using the special quasirandom structures\n(SQS) approach for alloys. We perform GGA-PBE calculations on all 495\npseudo-cubic perovskite structures and around 250 calculations using the HSE06\nfunctional, with and without spin-orbit coupling, both including geometry\noptimization and static calculations on PBE optimized structures. Lattice\nconstants, decomposition energy, band gap, and theoretical photovoltaic\nefficiency, are computed using each level of theory, and comparisons are made\nwith collected experimental values. Trends in the data are unraveled in terms\nof the effects of mixing at different sites, fractions of specific elemental or\nmolecular species present in the compound, and averaged physical properties of\nspecies at different sites. We perform screening across the perovskite dataset\nbased on multiple definitions of tolerance factors, deviation from cubicity,\ncomputed stability and optoelectronic properties, leading to a list of\npromising compositions and design principles for achieving multiple desired\nproperties. Our multi-objective, multi-fidelity, computational halide\nperovskite alloy dataset, one of the most comprehensive to date, is available\nopen-source, and currently being used to train predictive and optimization\nmodels for accelerating the design of novel compositions for superior\noptoelectronic applications."
    },
    {
        "anchor": "InN/In nanocomposites: Evidences of plasmonic effects and hidden gap: InN/In nanocomposites with periodical In inclusions amounting up to 30% of\nthe total volume exhibit bright emission near 0.7 eV explicitly associated with\nIn clusters. Its energy and intensity depend on the In amount. The principal\nabsorption edge in the semiconductor host, as given by a photovoltaic response,\nis markedly higher than the onset of thermally detected absorption. These\nfindings, being strongly suggestive of plasmon-dominated emission and\nabsorption, are discussed in terms of electromagnetic enhancement taking into\naccount the In parallel-band transitions.",
        "positive": "Unzipping hBN with ultrashort mid-infrared pulses: Manipulating the nanostructure of materials is critical for numerous\napplications in electronics, magnetics, and photonics. However, conventional\nmethods such as lithography and laser-writing require cleanroom facilities or\nleave residue. Here, we describe a new approach to create atomically sharp line\ndefects in hexagonal boron nitride (hBN) at room temperature by direct optical\nphonon excitation in the mid-infrared (mid-IR). We term this phenomenon\n\"unzipping\" to describe the rapid formation and growth of a <30-nm-wide crack\nfrom a point within the laser-driven region. The formation of these features is\nattributed to large atomic displacements and high local bond strain from\ndriving the crystal at a natural resonance. This process is distinguished by\n(i) occurring only under resonant phonon excitation, (ii) producing highly\nsub-wavelength features, and (iii) sensitivity to crystal orientation and pump\nlaser polarization. Its cleanliness, directionality, and sharpness enable\napplications in in-situ flake cleaving and phonon-wave-coupling via free space\noptical excitation."
    },
    {
        "anchor": "Algorithm for spin symmetry operation search: A spin space group provides a suitable way to fully exploit the symmetry of a\nspin arrangement with a negligible spin-orbit coupling. There has been a\ngrowing interest in applying spin symmetry analysis with the spin space group\nin the field of magnetism. However, there is no established algorithm to search\nfor spin symmetry operations of the spin space group. This paper presents an\nexhaustive algorithm for determining spin symmetry operations of commensurate\nspin arrangements. The present algorithm searches for spin symmetry operations\nfrom the symmetry operations of a corresponding nonmagnetic crystal structure\nand determines their spin-rotation parts by solving a Procrustes problem. An\nimplementation is distributed under a permissive free software license in\nspinspg v0.1.1: https://github.com/spglib/spinspg.",
        "positive": "Automatic Parameter Selection for Electron Ptychography via Bayesian\n  Optimization: Electron ptychography provides new opportunities to resolve atomic structures\nwith deep sub-angstrom spatial resolution and studying electron-beam sensitive\nmaterials with high dose efficiency. In practice, obtaining accurate\nptychography images requires simultaneously optimizing multiple parameters that\nare often selected based on trial-and-error, resulting in low-throughput\nexperiments and preventing wider adoption. Here, we develop an automatic\nparameter selection framework to circumvent this problem using Bayesian\noptimization with Gaussian processes. With minimal prior knowledge, the\nworkflow efficiently produces ptychographic reconstructions that are superior\nthan the ones processed by experienced experts. The method also facilitates\nbetter experimental designs by exploring optimized experimental parameters from\nsimulated data."
    },
    {
        "anchor": "Deterministic Domain Wall Motion Orthogonal To Current Flow Due To Spin\n  Orbit Torque: Deterministic control of domain walls orthogonal to the direction of current\nflow is demonstrated by exploiting spin orbit torque in a perpendicularly\npolarized Ta/CoFeB/MgO multilayer in presence of an in-plane magnetic field.\nNotably, such orthogonal motion with respect to current flow is not possible\nfrom traditional spin transfer torque driven domain wall propagation even in\npresence of an external magnetic field. Reversing the polarity of either the\ncurrent flow or the in-plane field is found to reverse the direction of the\ndomain wall motion. From these measurements, which are unaffected by any\nconventional spin transfer torque by symmetry, we estimate the spin orbit\ntorque efficiency of Ta to be 0.08.",
        "positive": "Skyrmion fractionalization and merons in chiral magnets with easy-plane\n  anisotropy: We study the equilibrium phase diagram of ultrathin chiral magnets with\neasy-plane anisotropy $A$. The vast triangular skyrmion lattice phase that is\nstabilized by an external magnetic field evolves continuously as a function of\nincreasing $A$ into a regime in which nearest-neighbor skyrmions start\noverlapping with each other. This overlap leads to a continuous reduction of\nthe skyrmion number from its quantized value $Q=1$ and to the emergence of\nantivortices at the center of the triangles formed by nearest-neighbor\nskyrmions. The antivortices also carry a small \"skyrmion number\" $Q_A \\ll 1$\nthat grows as a function of increasing $A$. The system undergoes a first order\nphase transition into a square vortex-antivortex lattice at a critical value of\n$A$. Finally, a canted ferromagnetic state becomes stable through another first\norder transition for a large enough anisotropy $A$. Interestingly enough, this\nfirst order transition is accompanied by {\\it metastable} meron solutions."
    },
    {
        "anchor": "Acoustic-Driven Magnetic Skyrmion Motion: Magnetic skyrmions have great potential for developing novel spintronic\ndevices. The electrical manipulation of skyrmions has mainly relied on\ncurrent-induced spin-orbit torques. A recent theoretical model suggested that\nthe skyrmions could be more efficiently manipulated by surface acoustic waves\n(SAW), an elastic wave that can couple with magnetic moment through\nmagnetoelastic effect. However, the directional motion of skyrmions that is\ndriven by SAW is still missing. Here, we experimentally demonstrate the motion\nof N\\'eel-type skyrmions in Ta/CoFeB/MgO/Ta multilayers driven by propagating\nSAW pulses from on-chip piezoelectric transducers. Our results reveal that the\nelastic wave with longitudinal and shear vertical displacements (Rayleigh wave)\ntraps skyrmions, while the shear horizontal wave effectively drives the motion\nof skyrmions. In particular, a longitudinal motion along the SAW propagation\ndirection and a transverse motion due to topological charge, are observed and\nfurther confirmed by our micromagnetic simulations. This work demonstrates a\npromising approach based on acoustic waves for manipulating skyrmions, which\ncould offer new opportunities for ultra-low power spintronics.",
        "positive": "Spin- and time-resolved photoelectron spectroscopy and diffraction\n  studies using time-of-flight momentum microscopes: Momentum microscopy (MM) is a novel way of performing angular-resolved\nphotoelectron spectroscopy (ARPES). Combined with time-of-flight (ToF) energy\nrecording, its high degree of parallelization is advantageous for photon-hungry\nexperiments like ARPES at X-ray energies and spin-resolved ARPES. This article\nintroduces into the spin-resolved variant of ToF-MM and illustrates its\nperformance by selected examples obtained in different spectral ranges. In a\nmultidimensional view of the photoemission process, spectral density function\n$\\rho(k,E_B)$, spin polarization $P(k,E_B)$ and related quantities of circular\ndichroism in the angular distribution (CDAD) are part of the complete\nexperiment, a concept adopted from atomic photoemission. We show examples of\nspin-resolved valence-band mapping in the UV, VUV, soft- and hard-X-ray range.\nSpin mapping of the Heusler compounds Co$_2$MnGa and\nCo$_2$Fe$_{0.4}$Mn$_{0.6}$Si at $h\\nu=6$~eV prove that the second compound is a\nhalf-metallic ferromagnet. Analysis of the Tamm state on Re(0001) using\nVUV-excitation reveals a Rashba-type spin texture. Bulk band structure\nincluding Fermi surface, Fermi velocity distribution $v_F(k,E_F)$, full CDAD\ntexture and spin signature of W(110) have been derived via tomographic mapping\nwith soft X-rays. Hard X-rays enable accessing large k$_{par}$-regions so that\nthe final-state sphere crosses many Brillouin zones in $k$-space with different\n$k_z$. At $h\\nu=5.3$~keV this fast 4D mapping mode (at fixed $h\\nu$) revealed\nthe temperature dependence of the Fermi surface of the Kondo system\nYbRh$_2$Si$_2$. Probing the true bulk spin polarization of Fe$_3$O$_4$ at\n$h\\nu=5$~keV proved its half-metallic nature. The emerging method of ToF-MM\nwith fs X-ray pulses from a free-electron laser enables simultaneous valence,\ncore-level and photoelectron diffraction measurements in the ultrafast regime."
    },
    {
        "anchor": "Ab initio Disordered Local Moment Approach for a Doped Rare-Earth Magnet: Following the finite-temperature ab initio calculation framework based on the\nrelativistic disordered local moments, we computationally demonstrate the\npossibility of doping-enhanced coercivity at high-temperatures, taking YCo$_5$\nas a working material in order to extract the $3d$-electron part of the\nelectronic structure of the rare-earth permanent magnets. Alkaline-earth\ndopants are shown to be the candidates to realize the proposed phenomenon.",
        "positive": "Melting of Spatially Modulated Phases in La-doped BiFeO3 at Surfaces and\n  Surface-Domain Wall Junctions: The interplay between the surface and domain wall phenomena in multiferroic\nLaxBi1-xFeO3 in the vicinity of morphotropic phase transition is explored on\nthe atomic level. Scanning Transmission Electron Microscopy (STEM) has enabled\nmapping of atomic structures of the material with picometer-level precision,\nproviding direct insight into the spatial distribution of the order parameters\nin this material and their behavior at surfaces and interfaces. Here, we use\nthe thermodynamic Landau-Ginzburg-Devonshire (LGD) approach to explain the\nemergence of spatially modulated phases (SMP) in La0.22Bi0.78FeO3 films, and\nestablish that the change of polarization gradient coefficients caused by\nLa-doping is the primary driving mechanisms. The suppression, or \"melting\", of\nthe SMP in the vicinity of the domain wall surface junction is observed\nexperimentally and simulated in the framework of LGD theory. The melting\noriginated from the system tendency to minimize electrostatic energy caused by\nlong-range stray electric fields outside the film and related depolarization\neffects inside it. The observed behavior provides insight to the origin of\nsurface and interface behaviors in multiferroics."
    },
    {
        "anchor": "Adsorption of CO and NO molecules on pristine, vacancy defected and\n  doped graphene-like GaN monolayer: A first-principles study: In order to study the novel gas detection or sensing applications of gallium\nnitride monolayer (GaN-ML), we mainly focused on the structural, energetic,\nelectronic and magnetic properties of toxic gas molecules (CO, NO) adsorbed on\npristine, single vacancy (N-vacancy, Ga-vacancy) defected, and metals (Al, Fe,\nPd and Pt) doped GaN-ML using density functional theory (DFT-D2 method) in this\nwork. The calculations demonstrate that pristine GaN-ML is extremely\ninsensitive to CO and NO together with the existence of a weak physisorption\nnature due to small adsorption energy, charge transfer, and long adsorption\ndistance. It is found that both N-vacancy defected GaN-ML and Fe-doped GaN-ML\ncan significantly increase the adsorption energy and charge transfer for CO.\nThe CO adsorption induces the metallic characteristics of N-vacancy GaN-ML to\nbe converted to the half-metallic characteristics together with 100% spin\npolarization, and it also drastically changes the magnetic moment, implying\nthat N-vacancy GaN-ML exhibits excellent sensitivity to CO. However, Fe-doped\nGaN-ML is not conducive to CO detection. Moreover, N-vacancy defected and\nPt-doped GaN-ML greatly improve the adsorption ability for NO compared to other\nsubstrates, and the presence of stronger orbital hybridization suggests that\nthe interaction between them is chemisorption. Therefore, N-vacancy defected\nGaN-ML and Pt-doped GaN-ML can serve as potential materials in future NO\nsensing devices.",
        "positive": "Stable ordered phases of cuprous iodide with complexes of copper\n  vacancies: We perform an exhaustive theoretical study of the phase diagram of Cu-I\nbinaries, focusing on Cu-poor compositions, relevant for p-type transparent\nconduction. We find that the interaction between neighboring Cu vacancies is\nthe determining factor that stabilizes non-stoichiometric zincblende phases.\nThis interaction leads to defect complexes where Cu vacancies align\npreferentially along the [100] crystallographic direction. It turns out that\nthese defect complexes have an important influence on hole conductivity, as\nthey lead to dispersive conducting $p$-states that extend up to around 0.8 eV\nabove the Fermi level. We furthermore observe a characteristic peak in the\ndensity of electronic states, which could provide an experimental signature for\nthis type of defect complexes."
    },
    {
        "anchor": "One-dimensional edge contacts to a monolayer semiconductor: Integration of electrical contacts into van der Waals (vdW) heterostructures\nis critical for realizing electronic and optoelectronic functionalities.\nHowever, to date no scalable methodology for gaining electrical access to\nburied monolayer two-dimensional (2D) semiconductors exists. Here we report\nviable edge contact formation to hexagonal boron nitride (hBN) encapsulated\nmonolayer MoS$_2$. By combining reactive ion etching, in situ Ar$^+$ sputtering\nand annealing, we achieve a relatively low edge contact resistance, high\nmobility (up to ~30 cm$^2$/Vs) and high on-current density (>50 uA/um at\nV$_{\\rm DS}$ = 3V), comparable to top contacts. Furthermore, the atomically\nsmooth hBN environment also preserves the intrinsic MoS$_2$ channel quality\nduring fabrication, leading to a steep subthreshold swing of 116 mV/dec with a\nnegligible hysteresis. Hence, edge contacts are highly promising for\nlarge-scale practical implementation of encapsulated heterostructure devices,\nespecially those involving air sensitive materials, and can be arbitrarily\nnarrow, which opens the door to further shrinkage of 2D device footprint.",
        "positive": "Dislocation Activities at the Martensite Phase Transformation Interface\n  in Metastable Austenitic Stainless Steel: An In-situ TEM Study: Understanding the mechanism of martensitic transformation is of great\nimportance in developing advanced high strength steels, especially\nTRansformation-Induced Plasticity (TRIP) steels. The TRIP effect leads to\nenhanced work-hardening rate, postponed onset of necking and excellent\nformability. In-situ transmission electron microscopy has been performed to\nsystematically investigate the dynamic interactions between dislocations and\nalpha martensite at microscale. Local stress concentrations, e.g. from notches\nor dislocation pile-ups, render free edges and grain boundaries favorable\nnucleation sites for alpha martensite. Its growth leads to partial dislocation\nemission on two independent slip planes from the hetero-interface when the\naustenite matrix is initially free of dislocations. The kinematic analysis\nreveals that activating slip systems on two independent {111} planes of\naustenite are necessary in accommodating the interfacial mismatch strain. Full\ndislocation emission is generally observed inside of austenite regions that\ncontain high density of dislocations. In both situations, phase boundary\npropagation generates large amounts of dislocations entering into the matrix,\nwhich renders the total deformation compatible and provide substantial strain\nhardening of the host phase. These moving dislocation sources enable plastic\nrelaxation and prevent local damage accumulation by intense slipping on the\nsofter side of the interfacial region. Thus, finely dispersed martensite\ndistribution renders plastic deformation more uniform throughout the austenitic\nmatrix, which explains the exceptional combination of strength and ductility of\nTRIP steels."
    },
    {
        "anchor": "The High-Flux Backscattering Spectrometer at the NIST Center for Neutron\n  Research: We describe the design and current performance of the high-flux\nbackscattering spectrometer located at the NIST Center for Neutron Research.\nThe design incorporates several state-of-the-art neutron optical devices to\nachieve the highest flux on sample possible while maintaining an energy\nresolution of less than 1mueV. Foremost among these is a novel phase-space\ntransformation chopper that significantly reduces the mismatch between the beam\ndivergences of the primary and secondary parts of the instrument. This resolves\na long-standing problem of backscattering spectrometers, and produces a\nrelative gain in neutron flux of 4.2. A high-speed Doppler-driven monochromator\nsystem has been built that is capable of achieving energy transfers of up to\n+-50mueV, thereby extending the dynamic range of this type of spectrometer by\nmore than a factor of two over that of other reactor-based backscattering\ninstruments.",
        "positive": "Tailoring Heat Dissipation in Ordered Arrays of Dipolar Coupled Magnetic\n  Nanoparticles: The main aim of the present work is to analyse the effect of dipolar\ninteraction strength $\\lambda$, particle size $D$ and temperature $T$ on the\nhysteresis mechanism in ordered arrays of magnetic nanoparticles (MNPs) using\ncomputer simulations. The anisotropy axes of the MNPs are assumed to have\nrandom orientation to mimic the real system. In the absence of thermal\nfluctuations and dipolar interaction, the hysteresis follows the Stoner and\nWohlfarth model irrespective of $D$, as expected. The hysteresis loop area is\nminimal for particle sizes $D \\approx8-16$ nm at $T=300$ K and $\\lambda=0.0$,\nindicating the dominance of superparamagnetic character. Switching magnetic\ninteraction on is able to move the MNPs from superparamagnetic to a\nferromagnetic state even at room temperature; therefore, magnetic interaction\nof enough strength enhances the hysteresis loop area. Interestingly, the\nhysteresis loop area is significant and is the same as that of Stoner and\nWohlfarth particle even $T=300$ K and negligible dipolar interaction for\nferromagnetic MNPs ($D>16$ nm). The coercive field $\\mu^{}_oH^{}_c$ and\nblocking temperature $T^{}_B$ also get enhanced with an increase in $\\lambda$\nand $D$. The rigorous analysis of the coercive field $\\mu^{}_oH^{}_c$ vs\ntemperature data also reveals significant deviation from $T^{3/4}$ dependence\nof $\\mu^{}_oH^{}_c$ because of dipolar interaction. The amount of heat\ndissipated $E^{}_H$ and $\\mu_oH^{}_c$ decrease rapidly with $T$ for $D\\approx\n8-16$ nm and $\\lambda\\leq0.6$. On the other hand, $E^{}_H$ and $\\mu^{}_oH^{}_c$\ndepend weakly on $T$ with $D>16$ nm, even in the weak dipolar limit. The\npresent work should provide a better understanding of magnetic hyperthermia to\nresearchers working on this subject. For physicists, it would be interesting to\ntest experimentally the results described in this article."
    },
    {
        "anchor": "Magnetism and high-magnetic field magnetization in alkali superoxide\n  CsO2: Alkali superoxide CsO2 is one of candidates for the spin-1/2 one-dimensional\n(1D) antiferromagnet, which may be sequentially caused by an ordering of the\npi-orbital of O2- molecule below TS ~ 70 K. Here, we report on the magnetism in\npowder CsO2 and high-magnetic field magnetization measurements in\npulsed-magnetic fields of up to 60 T. We obtained the low temperature phase\ndiagram around the antiferromagnetic ordering temperature TN = 9.6 K under the\nmagnetic field. At 1.3 K, remarkable up-turn curvature in the magnetization\naround a saturation field of ~ 60 T is found, which corresponds to the\nspin-1/2. We will compare it with the theoretical calculation.",
        "positive": "Towards predictive band gaps for halide perovskites: Lessons from\n  one-shot and eigenvalue self-consistent GW: Halide perovskites constitute a chemically-diverse class of crystals with\ngreat promise as photovoltaic absorber materials, featuring band gaps between\nabout 1 and 3.5 eV depending on composition. Their diversity calls for a\ngeneral computational approach to predicting their band gaps. However, such an\napproach is still lacking. Here, we use density functional theory (DFT) and\nmany-body perturbation theory within the GW approximation to compute the\nquasiparticle or fundamental band gap of a set of ten representative halide\nperovskites: CH$_3$NH$_3$PbI$_3$ (MAPbI$_3$), MAPbBr$_3$, CsSnBr$_3$,\n(MA)$_2$BiTlBr$_6$, Cs$_2$TlAgBr$_6$, Cs$_2$TlAgCl$_6$, Cs$_2$BiAgBr$_6$,\nCs$_2$InAgCl$_6$, Cs$_2$SnBr$_6$, and Cs$_2$Au$_2$I$_6$. Comparing with recent\nmeasurements, we find that a standard generalized gradient exchange-correlation\nfunctional can significantly underestimate the experimental band gaps of these\nperovskites, particularly in cases with strong spin-orbit coupling (SOC) and\nhighly dispersive band edges, to a degree that varies with composition. We show\nthat these nonsystematic errors are inherited by one-shot G$_0$W$_0$ and\neigenvalue self-consistent GW$_0$ calculations, demonstrating that semilocal\nDFT starting points are insufficient for MAPbI$_3$, MAPbBr$_3$, CsSnBr$_3$,\n(MA)$_2$BiTlBr$_6$, Cs$_2$TlAgBr$_6$, and Cs$_2$TlAgCl$_6$. On the other hand,\nwe find that DFT with hybrid functionals leads to an improved starting point\nand GW$_0$ results in better agreement with experiment for these perovskites.\nOur results suggest that GW$_0$ with hybrid functional-based starting points\nare promising for predicting band gaps of systems with large SOC and dispersive\nbands in this technologically important class of semiconducting crystals."
    },
    {
        "anchor": "Effect of inhomogeneous Dzyaloshinskii-Moriya interaction on\n  antiferromagnetic spin-wave propagation: We investigate the effect of inhomogeneous Dzyaloshinskii-Moriya interaction\n(DMI) on antiferromagnetic spin-wave propagation theoretically and numerically.\nWe find that antiferromagnetic spin waves can be amplified at a boundary where\nthe DMI varies. The inhomogeneous DMI also provides a way to construct a\nmagnonic crystal with forbidden and allowed antiferromagnetic spin-wave bands\nin terahertz frequency ranges. In contrast to ferromagnetic spin waves,\nantiferromagnetic spin waves experience a polarization-dependent phase shift\nwhen passing through the inhomogeneous DMI, offering a magnonic crystal that\nalso serves as a spin-wave polarizer.",
        "positive": "Impact of Dielectric Environment on Trion Emission from Single-Walled\n  Carbon Nanotube Networks: Trions are charged excitons that form upon optical or electrical excitation\nof low-dimensional semiconductors in the presence of charge carriers (holes or\nelectrons). Trion emission from semiconducting single-walled carbon nanotubes\n(SWCNTs) occurs in the near-infrared and at lower energies compared to the\nrespective exciton. It can be used as an indicator for the presence of excess\ncharge carriers in SWCNT samples and devices. Both excitons and trions are\nhighly sensitive to the surrounding dielectric medium of the nanotubes, having\nan impact on their application in optoelectronic devices. Here, the influence\nof different dielectric materials on exciton and trion emission from\nelectrostatically doped networks of polymer-sorted (6,5) SWCNTs in top-gate\nfield-effect transistors is investigated. The observed differences of trion and\nexciton emission energies and intensities for hole and electron accumulation\ncannot be explained with the polarizability or screening characteristics of the\ndifferent dielectric materials, but they show a clear dependence on the charge\ntrapping properties of the dielectrics. Charge localization (trapping of holes\nor electrons by the dielectric) reduces exciton quenching, emission blue-shift\nand trion formation. Based on the observed carrier type and dielectric material\ndependent variations, the ratio of trion to exciton emission and the exciton\nblue-shift are not suitable as quantitative metrics for doping levels of carbon\nnanotubes."
    },
    {
        "anchor": "Robustness of electronic screening effects in electron spectroscopies:\n  example of V$_2$O$_5$: In bulk and low-dimensional extended systems, the screening of excitations by\nthe electron cloud is a key feature governing spectroscopic properties. Widely\nused computational approaches, especially in the framework of many-body\nperturbation theory, such as the GW approximation and the resulting approximate\nBethe-Salpeter equation, are explicitly formulated in terms of the screened\nCoulomb interaction. In the present work we explore the effect of screening in\nabsorption and electron energy loss spectroscopy, concentrating on the effect\nof local distortions on the screening and elucidating the resulting changes in\nthe various spectra. Using the layered bulk oxide V$_2$O$_5$ as prototype\nmaterial, we show in which way local distortions affect the screening, and in\nwhich way changes in the screening impact electron energy loss and absorption\nspectra including excitons. We highlight cancellations that make many-body\neffects in the spectra very robust with respect to structural modifications,\nwhile the band structure undergoes significant changes and the nature of the\nexcitations may also be affected. This yields insight concerning the\nstructure-properties relations that are crucial for the use of V$_2$O$_5$ as\nenergy storage material, and more generally, that may be used to optimize the\nanalysis and the calculation of electronic spectra in complex materials.",
        "positive": "Polar State in Freestanding Strontium Titanate Nanoparticles: Monodispersed strontium titanate nanoparticles were prepared and studied in\ndetail. It is found that ~10 nm as-prepared stoichiometric nanoparticles are in\na polar structural state (with possibly ferroelectric properties) over a broad\ntemperature range. A tetragonal structure, with possible reduction of the\nelectronic hybridization is found as the particle size is reduced. In the 10 nm\nparticles, no change in the local Ti-off centering is seen between 20 and 300\nK. The results indicate that nanoscale motifs of SrTiO3 may be utilized in data\nstorage as assembled nano-particle arrays in applications where chemical\nstability, temperature stability and low toxicity are critical issues."
    },
    {
        "anchor": "Uncovering polar vortex structures by inversion of multiple scattering\n  with a stacked Bloch wave model: Nanobeam electron diffraction can probe local structural properties of\ncomplex crystalline materials including phase, orientation, tilt, strain, and\npolarization. Ideally, each diffraction pattern from a projected area of a few\nunit cells would produce clear a Bragg diffraction pattern, where the\nreciprocal lattice vectors can be measured from the spacing of the diffracted\nspots, and the spot intensities are equal to the square of the structure factor\namplitudes. However, many samples are too thick for this simple interpretation\nof their diffraction patterns, as multiple scattering of the electron beam can\nproduce a highly nonlinear relationship between the spot intensities and the\nunderlying structure. Here, we develop a stacked Bloch wave method to model the\ndiffracted intensities from thick samples with structure that varies along the\nelectron beam. Our method reduces the large parameter space of electron\nscattering to just a few structural variables per probe position, making it\nfast enough to apply to very large fields of view. We apply our method to\nSrTiO$_3$/PbTiO$_3$/SrTiO$_3$ multilayer samples, and successfully disentangle\nspecimen tilt from the mean polarization of the PbTiO$_3$ layers. We elucidate\nthe structure of complex vortex topologies in the PbTiO$_3$ layers,\ndemonstrating the promise of our method to extract material properties from\nthick samples.",
        "positive": "Origin of the spin reorientation transitions in\n  (Fe$_{1-x}$Co$_{x}$)$_{2}$B alloys: Low-temperature measurements of the magnetocrystalline anisotropy energy $K$\nin (Fe$_{1-x}$Co$_{x}$)$_{2}$B alloys are reported, and the origin of this\nanisotropy is elucidated using a first-principles electronic structure\nanalysis. The calculated concentration dependence $K(x)$ with a maximum near\n$x=0.3$ and a minimum near $x=0.8$ is in excellent agreement with experiment.\nThis dependence is traced down to spin-orbital selection rules and the filling\nof electronic bands with increasing electronic concentration. At the optimal Co\nconcentration, $K$ depends strongly on the tetragonality and doubles under a\nmodest 3% increase of the $c/a$ ratio, suggesting that the magnetocrystalline\nanisotropy can be further enhanced using epitaxial or chemical strain."
    },
    {
        "anchor": "Evidence for multiferroicity in TTF-CA organic molecular crystals: We show by means of ab-initio calculations that the organic molecular crystal\nTTF-CA is multiferroic: it has an instability to develop spontaneously both\nferroelectric and magnetic ordering. Ferroelectricity is driven by a Peierls\ntransition of the TTF-CA in its ionic state. Subsequent antiferromagnetic\nordering strongly enhances the opposing electronic contribution to the\npolarization: it is so large that it switches the direction of the total\nferroelectric moment. Within an extended Hubbard model we capture the essence\nof the electronic interactions in TTF-CA, confirm the presence of a\nmultiferroic groundstate and clarify how this state develops microscopically.",
        "positive": "Structural, vibrational, and quasiparticle band structure of 1, 1 -\n  diamino-2, 2 - dinitroethelene from ab-initio calculations: The effect of pressure on the structural and vibrational properties of the\nlayered molecular crystal 1,1-diamino-2,2-dinitroethelene (FOX-7) are explored\nby first principles calculations. We observe significant changes in the\ncalculated structural properties with different corrections for treating van\nder Waals interactions to Density Functional Theory (DFT), as compared with\nstandard DFT functionals. In particular, the calculated ground state lattice\nparameters, volume and bulk modulus obtained with Grimme's scheme are found to\nagree well with experiments. The calculated vibrational frequencies\ndemonstrates the dependence of the intra and inter-molecular interactions in\nFOX-7 under pressure. In addition, we also found a significant increment in the\nN-H...O hydrogen bond strength under compression. This is explained by the\nchange in bond lengths between nitrogen, hydrogen and oxygen atoms, as well as\ncalculated IR spectra under pressure. Finally, the computed band gap is about\n2.3 eV with GGA, and is enhanced to 5.1 eV with the GW approximation, which\nreveals the importance of performing quasiparticle calculations in high energy\ndensity materials."
    },
    {
        "anchor": "Density functional simulations of pressurized Mg-Zn and Al-Zn alloys: The Mg-Zn and Al-Zn binary alloys have been investigated theoretically under\nstatic isotropic pressure. The stable phases of these binaries on both\ninitially hexagonal-close-packed (HCP) and face-centered-cubic (FCC) lattices\nhave been determined by utilizing an iterative approach that uses a\nconfigurational cluster expansion method, Monte Carlo search algorithm, and\ndensity functional theory (DFT) calculations. Based on 64-atom models, it is\nshown that the most stable phases of the Mg-Zn binary alloy under ambient\ncondition are $\\rm MgZn_3$, $\\rm Mg_{19}Zn_{45}$, $\\rm MgZn$, and $\\rm\nMg_{34}Zn_{30}$ for the HCP, and $\\rm MgZn_3$ and $\\rm MgZn$ for the FCC\nlattice, whereas the Al-Zn binary is energetically unfavorable throughout the\nentire composition range for both the HCP and FCC lattices under all\nconditions. By applying an isotropic pressure in the HCP lattice, $\\rm\nMg_{19}Zn_{45}$ turns into an unstable phase at P$\\approx$$10$~GPa, a new\nstable phase $\\rm Mg_{3}Zn$ appears at P$\\gtrsim$$20$~GPa, and $\\rm\nMg_{34}Zn_{30}$ becomes unstable for P$\\gtrsim$$30$~GPa. For FCC lattice, the\n$\\rm Mg_{3}Zn$ phase weakly touches the convex hull at P$\\gtrsim$$20$~GPa while\nthe other stable phases remain intact up to $\\approx$$120$~GPa. Furthermore,\nmaking use of the obtained DFT results, bulk modulus has been computed for\nseveral compositions up to pressure values of the order of $\\approx$$120$~GPa.\nThe findings suggest that one can switch between $\\rm Mg$-rich and $\\rm\nZn$-rich early-stage clusters simply by applying external pressure. $\\rm\nZn$-rich alloys and precipitates are more favorable in terms of stiffness and\nstability against external deformation.",
        "positive": "Revealing the nanoparticle composition of Edvard Munch's The Scream, and\n  implications for paint alteration in iconic early 20th century artworks: A major motivation for the scientific study of artworks is to understand\ntheir states of preservation and ongoing degradation mechanisms. This enables\npreservation strategies to be developed for irreplaceable works. Intensely-hued\ncadmium sulphide (CdS) yellow pigments are of particular interest because these\nare key to the palettes of many important late 19th and early 20th century\nmasters, including Vincent Van Gogh, Pablo Picasso, Henri Matisse, and Edvard\nMunch. As these paintings age, their cadmium yellow paints are undergoing\nsevere fading, flaking, and discolouration. These effects are associated with\nphotodegradation, the light-facilitated reactions of CdS with oxygen, moisture,\nand even the paint binding medium. The use of common optical and X-ray methods\nto characterize the physical state of the pigment is challenging due to the\nmixing of the various components of the paint at length scales smaller than\ntheir resolution. Here, we present an atomic-scale structural and chemical\nanalysis of the CdS pigment in Edvard Munch's The Scream (c. 1910, Munch\nMuseet), enabled by new electron microscope detector technologies. We show that\nthe CdS pigment consists of clusters of defective nanoparticles ~5-10 nm in\ndiameter. It is known from the modern use of such particles in photocatalysis\nthat they are inherently vulnerable to photodegradation. Chlorine doping and a\npolytype crystal structure further enhance the sensitivity of the CdS pigment\nto photodegradation. In addition to The Scream, we have also observed this\ninherently unstable pigment structure in Henri Matisse's Flower Piece (1906,\nBarnes Foundation). The fundamental understanding of the pigments' nanoscale\nstructures and impurities described here can now be used to predict which\npaintings are most at risk of photooxidation, and guide the most effective\npreservation strategies for iconic masterpieces."
    },
    {
        "anchor": "Magnetically Controlling the Explosion of Dirac Fermions during the\n  Oxidation of Graphene: The different physical properties of multilayered graphene or graphite\nrelative to single layer graphene result from the Dirac spins symmetry in\ngraphene and the Pauli spin symmetry in graphite. The Dirac symmetry in\nmultilayers of graphene (graphite) is hindered by interlayer interactions.\nDifferent magnetizations, electronics and chemistry of graphite and graphene\nfollow from absence of interlayer interactions in graphene. The distinct\nkinetics and dynamics of graphite and graphene by oxidation by the Hummer's\nmethod in weak external magnetic field are observed in this work. Graphite\nmanifest enhanced non-explosive oxidation of Pauli spins in weak magnetic field\nwith background paramagnetic oxygen slowing the magnetic acceleration. Graphene\nand graphite oxide manifest explosive oxidation and magnetically decelerated\nexplosive oxidation of Dirac spins in weak magnetic field for temperatures\nbelow 20 oCelsius. The explosive oxidation of graphene and its deceleration in\nweak external magnetic field are interpreted resulting from the giant\nnonlocality and spin Hall Effect in the chemically reacting graphene. This is\nthe first identification, analysis and interpretation of the chemistry of the\nDirac spins and the magnetochemistry of relativistic electrons.",
        "positive": "Electronic structure of S-C6H5 self-assembled monolayers on Cu(111) and\n  Au(111) substrates: We use first principles density functional theory to calculate the electronic\nstructure of the phenylthiolate (S-C$_6$H$_5$) self-assembled monolayer (SAM)\non Cu(111) and Au(111) substrates. We find significant lateral dispersion of\nthe SAM molecular states and discuss its implications for transport properties\nof the molecular wire array. We calculate the two photon photoemission spectra\nand the work function of the SAM on Cu(111) and compare them with the available\nexperimental data. Our results are used to discuss assignments of the observed\nspectral data and yield predictions for new electronic states due to the\nmonolayer not yet accessed experimentally."
    },
    {
        "anchor": "Electronic properties of Mn-Phthalocyanine - C$_{60}$ bulk\n  heterojunctions: combining photoemission and electron energy-loss\n  spectroscopy: The electronic properties of co-evaporated mixtures (blends) of manganese\nphthalocyanine and the fullerene C$_{60}$ (MnPc:C$_{60}$) have been studied as\na function of the concentration of the two constituents using two supplementary\nelectron spectroscopic methods, photoemission spectroscopy (PES) as well as\nelectron energy-loss spectroscopy (EELS) in transmission. Our PES measurements\nprovide a detailed picture of the electronic structure measured with different\nexcitation energies as well as different mixing ratios between MnPc and\nC$_{60}$. Besides a relative energy shift, the occupied electronic states of\nthe two materials remain essentially unchanged. The observed energy level\nalignment is different compared to that of the related CuPc:C$_{60}$ bulk\nheterojunction. Moreover, the results from our EELS investigations show that\ndespite of the rather small interface interaction the MnPc related electronic\nexcitation spectrum changes significantly by admixing C$_{60}$ to MnPc thin\nfilms.",
        "positive": "Phonon Bandgap Engineering of Strained Monolayer MoS2: The phonon band structure of monolayer MoS2 is characteristic for a large\nenergy gap between acoustic and optical branches, which protects the vibration\nof acoustic modes from being scattered by optical phonon modes. Therefore, the\nphonon bandgap engineering is of practical significance for the manipulation of\nphonon-related mechanical or thermal properties in monolayer MoS2. We perform\nboth phonon analysis and molecular dynamics simulations to investigate the\ntension effect on the phonon bandgap and the compression induced instability of\nthe monolayer MoS2. Our key finding is that the phonon bandgap can be narrowed\nby the uniaxial tension, and is completely closed at epsilon=0.145; while the\nbiaxial tension only has limited effect on the phonon bandgap. We also\ndemonstrate the compression induced buckling for the monolayer MoS2. The\ncritical strain for buckling is extracted from the band structure analysis of\nthe flexure mode in the monolayer MoS2 and is further verified by molecular\ndynamics simulations and the Euler buckling theory. Our study illustrates the\nuniaxial tension as an efficient method for manipulating the phonon bandgap of\nthe monolayer MoS2, while the biaxial compression as a powerful tool to\nintrigue buckling in the monolayer MoS2."
    },
    {
        "anchor": "Fundamental Distinction between Intrinsic and Extrinsic Nonlinear\n  Thermal Hall Effects: We theoretically investigated the fundamental distinction between intrinsic\nand extrinsic nonlinear thermal Hall effect in the presence of disorder at the\nsecond-order response to the temperature gradient in terms of the\nsemi-classical Boltzmann equation. We found that, at low temperatures, the\nintrinsic contribution of the nonlinear thermal Hall conductivity is\nproportional to the square of temperature, whereas the extrinsic contributions\n(side-jump and skew-scattering) are independent of temperature. This distinct\ndependency on temperature provide a new approach to readily distinguish the\nintrinsic and extrinsic contributions. Specifically, we analysed the nonlinear\nthermal Hall effect for a tilted two-dimensional massive Dirac material. In\nparticular, we showed that when the Fermi energy is located at the Dirac point,\nthe signal is solely from the intrinsic mechanism; when the Fermi energy is\nhigher, the extrinsic contributions are dominant, which are uncovered to be two\nto three orders of magnitude larger than the intrinsic contribution.",
        "positive": "Coupled spin-lattice dynamics from the tight-binding electronic\n  structure: We developed a method which performs the coupled adiabatic spin and lattice\ndynamics based on the tight-binding electronic structure model, where the\nintrinsic magnetic field and ionic forces are calculated from the converged\nself-consistent electronic structure at every time step. By doing so, this\nmethod allows us to explore limits where the physics described by a\nparameterized spin-lattice Hamiltonian is no longer accurate. We demonstrate\nhow the lattice dynamics is strongly influenced by the underlying magnetic\nconfiguration, where disorder is able to induce significant lattice\ndistortions. The presented method requires significantly less computational\nresources than ab initio methods, such as time-dependent density functional\ntheory (TD-DFT). Compared to parameterized Hamiltonian-based methods, it also\ndescribes more accurately the dynamics of the coupled spin and lattice degrees\nof freedom, which becomes important outside of the regime of small lattice and\nspin fluctuations."
    },
    {
        "anchor": "Near Unity Absorption in Van der Waals Semiconductors for Ultrathin\n  Optoelectronics: We demonstrate near unity, broadband absorbing optoelectronic devices using\nsub-15 nm thick transition metal dichalcogenides (TMDCs) of molybdenum and\ntungsten as van der Waals semiconductor active layers. Specifically, we report\nthat near-unity light absorption is possible in extremely thin (< 15 nm) Van\nder Waals semiconductor structures by coupling to strongly damped optical modes\nof semiconductor/metal heterostructures. We further fabricate Schottky junction\ndevices using these highly absorbing heterostructures and characterize their\noptoelectronic performance. Our work addresses one of the key criteria to\nenable TMDCs as potential candidates to achieve high optoelectronic efficiency.",
        "positive": "Exploring energy landscapes of charge multipoles using constrained\n  density functional theory: We present a method to constrain local charge multipoles within\ndensity-functional theory. Such multipoles quantify the anisotropy of the local\ncharge distribution around atomic sites and can indicate potential hidden\norders. Our method allows selective control of specific multipoles,\nfacilitating a quantitative exploration of the energetic landscape outside of\nlocal minima. Thus, it enables a clear distinction between electronically and\nstructurally driven instabilities. We demonstrate the effectiveness of this\nmethod by applying it to charge quadrupoles in the prototypical orbitally\nordered material KCuF$_3$. We quantify intersite multipole-multipole\ninteractions as well as the energy-lowering related to the formation of an\nisolated local quadrupole. We also map out the energy as a function of the size\nof the local quadrupole moment around its local minimum, enabling\nquantification of multipole fluctuations around their equilibrium value.\nFinally, we study charge quadrupoles in the solid solution\nKCu$_{1-x}$Zn$_x$F$_3$ to characterize the behavior across the\ntetragonal-to-cubic transition. Our method provides a powerful tool for\nstudying symmetry breaking in materials with coupled electronic and structural\ninstabilities and potentially hidden orders."
    },
    {
        "anchor": "First principles simulations of the magnetic and structural properties\n  of Iron: We have implemented non-collinear GGA and a generalized Bloch's theorem to\nsimulate unconmensurate spiral arrangements of spins in a Density Functional\nTheory code based on localized wave functions. We have subsequently performed a\nthorough study of the different states of bulk Iron. We determine the minimal\nbasis set required to obtain reliable orderings of ground and excited states.\nWe find that the most stable fcc phase is a spiral with an equilibrium lattice\nconstant 3.56 A.",
        "positive": "High-throughput characterization of transition metal dichalcogenide\n  alloys: Thermodynamic stability and electronic band alignment: Alloying offers a way to tune many of the properties of the transition metal\ndichalcogenide (TMD) monolayers. While these systems in many cases have been\nthoroughly investigated previously, the fundamental understanding of critical\ntemperatures, phase diagrams and band edge alignment is still incomplete. Based\non first principles calculations and alloy cluster expansions we compute the\nphase diagrams 72 TMD monolayer alloys and classify the mixing behavior. We\nshow that ordered phases in general are absent at room temperature but that\nthere exists some alloys, which have a stable Janus phase at room temperature.\nFurthermore, for a subset of these alloys, we quantify the band edge bowing and\nshow that the band edge positions for the mixing alloys can be continuously\ntuned in the range set by the boundary phases."
    },
    {
        "anchor": "Using multicomponent recycled electronic waste alloys to produce high\n  entropy alloys: The amount of electronic waste (e-waste) recycled worldwide is less than 20%\nof the total amount produced. In a world where the need for critical and\nstrategic metals is increasing almost exponentially, it is unacceptable that\ntons of these elements remain unrecycled. One of the causes of this low level\nof recycling is that recycling is based on an expensive and complex selective\nsorting of metals. Extracting all metals simultaneously is much simpler and if\nthis were done, it would significantly increase the recycling rate. Meanwhile,\nit was demonstrated that high entropy alloys (HEAs), which are in great demand\nin applications where very high performance is required, can be made from\nmixtures of complex alloys, hence reducing their dependence on pure critical\nmetals. Here, we show that it is possible to obtain competitive HEAs from\ncomplex alloy mixtures corresponding to typical electronic waste compositions,\ncombining two needs of high interest in our society, namely: to increase the\nlevel of recycling of electronic waste and the possibility of developing\nhigh-performance HEAs without the need of using critical and/or strategic\nmetals. To validate our hypothesis that e-waste can be used to produce\ncompetitive HEAs, we propose an alloy design strategy combining computational\nthermodynamics (CalPhaD) exploration of phase diagrams and phenomenological\ncriteria for HEA design based on thermodynamic and structural parameters. A\nshortlist of selected compositions are then fabricated by arc melting ensuring\ncompositional homogeneity of such complex alloys and, finally, characterised\nmicrostructurally, using electron microscopy and diffraction analysis, and\nmechanically, using hardness testing.",
        "positive": "A closer look at how symmetry constraints and the spin-orbit coupling\n  shape the electronic structure of Bi(111): Relativistic density-functional-theory calculations of Bi(111) thin films are\nperformed to revisit their band structure and that of macroscopic samples. The\nband structure of a our 39-bilayer film ($\\sim$~15~nm) shows that (1)\n$\\sim$9-nm films are enough to describe that of Bi(111), (2) The two split\nsurface-state metallic branches along the $\\overline{\\Gamma M}$ direction do\nnot overlap with the bulk band at the zone boundary but lie within the\nA7-distortion-induced conduction-valence band gap, and (3) Neither the\nexistence of the metallic surface states nor their observed splitting is\nrelated to inversion \\emph{asymmetry}. Thus, the spin texture observed in such\nstates is not caused by the lifting of the Kramers degeneracy and their\nsplitting is not of the Rashba-type. We instead propose that (1) the large\nsplitting of the metallic branches is a $m_j=\\pm1/2$-$m_j=\\pm3/2$ splitting and\n(2) the spin texture observed for the metallic branches may only occur because\nthe almost unaltered strong covalent bonds retained by Bi(111) surface atoms\ncannot afford magnetic polarization. We emphasize that degeneracy at the\n$M$-point of the SBZ of Bi(111) -- implied by the translational symmetry of the\nsurface -- is satisfied irrespectively of the presence of inversion symmetry\ncenters. We show that the magnetic-moment discontinuity at $M$ does not exist,\nwhich also explains why the measured spin-polarization of the metallic branches\nvanishes near $M$. We induce the Rashba effect on the band structure of Bi(111)\nvia different structural/electronic perturbations to reveal the actual lifting\nof the Kramers degeneracy and find that the magnitude of the perturbation\nimposed on a film correlates with the magnitude of the splitting and the\nlocalization of the Rashba-split states."
    },
    {
        "anchor": "Impact of the crystal orientation on spin-orbit torques in Fe/Pd\n  bilayers: Spin-orbit torques in ferromagnetic (FM)/non-magnetic (NM) heterostructures\noffer more energy-efficient means to realize spin-logic devices; however, their\nstrengths are determined by the heterostructure interface. This work examines\ncrystal orientation impact on the spin-orbit torque efficiency in different\nFe/Pd bilayer systems. Spin torque ferromagnetic measurements evidence that the\ndamping-like torque efficiency is higher in epitaxial than in polycrystalline\nbilayer structures while the field-like torque is negligible in all bilayer\nstructures. The strength of the damping-like torque decreases with\ndeterioration of the bilayer epitaxial quality. The present finding provides\nfresh insight for the enhancement of spin-orbit torques in magnetic\nheterostructures.",
        "positive": "Mechanical, optical, and thermoelectric properties of semiconducting\n  ZnIn2X4 (X= S, Se, Te) monolayers: Mechanical stability of the ZnIn2X4 monolayers. The ZnIn2S4 and ZnIn2Se4 are\nsemiconductors with direct band gaps of 3.94 and 2.77 eV, respectively whereas\nthe ZnIn2Te4 shows an indirect band gap of 1.84 eV at the G0W0 level. The\noptical properties achieved from the solution of the Bethe-Salpeter equation\npredict the exciton binding energy of the ZnIn2S4, ZnIn2Se4, and ZnIn2Te4\nmonolayers to be 0.51, 0.41, and 0.34 eV, respectively, suggesting the high\nstability of the excitonic states against thermal dissociation. Using the\niterative solutions of the Boltzmann transport equation accelerated by machine\nlearning interatomic potentials, the room-temperature lattice thermal\nconductivity of the ZnIn2S4, ZnIn2Se4, and ZnIn2Te4 monolayers is predicted to\nbe remarkably low as 5.8, 2.0, and 0.4 W/mK, respectively. Due to the low\nlattice thermal conductivity, high thermopower, and large figure of merit, we\npropose the ZnIn2Se4 and ZnIn2Te4 monolayers as promising candidates for\nthermoelectric energy conversion systems. This study provides an extensive\nvision concerning the intrinsic physical properties of the ZnIn2X4 nanosheets\nand highlights their characteristics for energy conversion and optoelectronics\napplications."
    },
    {
        "anchor": "Functionality-directed Screening of Pb-free Hybrid Organic-inorganic\n  Perovskites with Desired Intrinsic Photovoltaic Functionalities: The material class of hybrid organic-inorganic perovskites has risen rapidly\nfrom a virtually unknown material in photovoltaic applications a short 7 years\nago into a ~20% efficient thin-film solar cell material. As promising as this\nclass of materials is, however, there are limitations associated with its poor\nlong-term stability, non-optimal band gap, presence of environmentally-toxic Pb\nelement, etc. We herein apply a functionality-directed theoretical materials\nselection approach as a filter for initial screening of the compounds that\nsatisfy the desired intrinsic photovoltaic functionalities and might overcome\nthe above limitations. First-principles calculations are employed to\nsystemically study thermodynamic stability and photovoltaic-related properties\nof hundred of candidate hybrid perovskites. We have identified in this\nmaterials selection process fourteen Ge and Sn-based materials with potential\nsuperior bulk-material-intrinsic photovoltaic performance. A distinct class of\ncompounds containing NH3COH$^+$ with the organic molecule derived states\nintriguingly emerging at band-edges is found. Comparison of various candidate\nmaterials offers insights on how composition variation and microscopic\nstructural changes affect key photovoltaic relevant properties in this family\nof materials.",
        "positive": "A Rate Model of Electron Populations for Non-linear High-Fluence X-ray\n  Absorption Near-Edge Spectra: Absorbing a focused, femtosecond X-ray pulse from a Free-Electron Laser (FEL)\ncan lead to extreme electronic excitations in solids. This excitation drives\nchanges of the electronic system over the course of the pulse duration and the\noverall absorption of the pulse becomes fluence-dependent. Thus,\nfluence-dependent non-linear X-ray Absorption Near Edge Spectroscopy (XANES) is\nsensitive to the valence excitation dynamics around the Fermi level on the\nfew-femtosecond timescale. Here we present a simplified rate model based on\nwell-established physical mechanisms to describe the evolution of the\nelectronic system. We construct temporal and spatial differentials for the\nprocesses of resonant absorption, stimulated emission, non-resonant absorption,\nAuger decay, valence band thermalization and scattering cascades of free\nelectrons. The phenomenological rate model approach provides a direct\nunderstanding how each physical process contributes to the fluence-dependent\nchanges observed in XANES measurements. Without accounting for\nfluence-dependent changes to the density of states, the model shows good\nagreement with experimental results on metallic nickel over more than three\norders of magnitude in fluence, establishing electron redistribution as the\nmain driver of non-linear absorption changes at high fluences. Although in the\nclosest vicinity of the resonance, more complex approaches are necessary to\ndescribe remaining discrepancies of the fluence-dependence changes, the\ndemonstrated capability to describe spectral changes up to extreme fluences\nyields fundamental insights into the complex dynamics after intense core\nexcitation and provides an important tool for the design and evaluation of\nfuture FEL experiments, in particular for the development of non-linear X-ray\nspectroscopy."
    },
    {
        "anchor": "Topologically nontrivial electronic states in CaSn$_{3}$: Based on the first-principles calculations, we theoretically propose\ntopologically non-trivial states in a recently experimentally discovered\nsuperconducting material CaSn$_3$. When the spin-orbit coupling (SOC) is\nignored, the material is a host to three-dimensional topological nodal-line\nsemimetal states. Drumhead like surface states protected by the coexistence of\ntime-reversal and mirror symmetry emerge within the two-dimensional regions of\nthe surface Brillouin zone connecting the nodal lines. When SOC is included,\nunexpectedly, each nodal line evolves into two Weyl nodes (W1, W2) in this\ncentrosymmetric material. Berry curvature calculations show that these nodes\noccur in a pair and act as either a source or sink of Berry flux. The material\nalso has unique surface states in the form of Fermi arcs, which unlike other\nknown Weyl semimetal, form closed loops of surface states on the Fermi surface.\nOur theoretical realization of topologically non-trivial states in a\nsuperconducting material paves the way towards unraveling the interconnection\nbetween topological physics and superconductivity.",
        "positive": "Phase diagrams and polar properties of ferroelectric nanotubes and\n  nanowires: In this paper we study the size effects of the ferroelectric nanotube and\nnanowire phase diagrams and polar properties allowing for radial stress and\ndepolarization field influence. The approximate analytical expression for the\nparaelectric-ferroelectric transition temperature dependence on the radii of\nnanotube, polarization gradient coefficient, extrapolation length, radial\nstress (surface tension) and electrostriction coefficient was derived. It was\nshown that the transition temperature could be higher than the one of the bulk\nmaterial for negative electrostriction coefficient and small depolarization\nfield. Therefore we predict conservation and enhancement of polar properties in\nlong cylindrical ferroelectric nanoparticles. Obtained results explain the\nobserved ferroelectricity conservation and enhancement in Pb(Zr,Ti)O_3 and\nBaTiO_3 nanowires and nanotubes. Moreover, despite made assumptions and\napproximations our modelling appeared in a surprisingly good agreement with\nobserved ferroelectric and local piezoresponse hysteresis loops."
    },
    {
        "anchor": "Unusual effects of manual grinding and subsequent annealing process\n  observed in Gd5.09Ge2.03Si1.88 compound: The Gd5.09Ge2.03Si1.88 compound, as well as other magnetocaloric materials,\ncertainly will not be used in their un-manufactured as-cast condition in future\nmagnetic refrigeration applications or other devices. In this work, we have\nstudied the Gd5.09Ge2.03Si1.88 compound processed in different ways, mainly,\nthe as-cast powder, the annealed powder and the pressed and sintered powder.\nThe annealed powder (1370 K / 20 hours) does not present the monoclinic phase\nand the first-order-magneto-structural transition observed in the as-cast\npowder. The pressed and sintered powder also do not present the first-order\ntransition. Furthermore, the compacting pressure shifts the\nsecond-order-magnetic transition to lower temperatures. The behavior of cell\nparameters as a function of the compacting pressure indicates that TC is\ndirectly affected by parameter c change.",
        "positive": "Room-temperature strong coupling of hexane-dispersed colloidal CdSe\n  nanoplatelets in a microcavity composed of two Bragg reflectors: CdSe nanoplatelets (NPLs) are suitable for exploring strong light-matter\ncoupling in semiconductor nanocrystal systems due to their giant oscillator\nstrength and large exciton binding energy. Herein, we report on the facile\nfabrication and optical characterization of a half-wavelength planar\nmicrocavity, which consists of two distributed Bragg reflectors with a hexane\nlayer containing concentrated colloidal CdSe NPLs. Using a hexane solution\nlayer instead of the typically used dried active layers makes the layer thin\nand flat, even under dense NPL conditions, without stressing or charging of the\nNPLs' surfaces. Reflectance spectra showed that strong light-matter coupling\ncan be realized at room temperature and that the vacuum Rabi splitting energy\nis 53.5 meV. Intense photoluminescence (PL) emerges at the lower polariton\nbranch where 25.1 meV (longitudinal optical (LO)-phonon energy) below the\nenergy of the polariton dark states, indicating that the relaxation from the\ndark states occurs efficiently in this microcavity owing to LO-phonon-assisted\nrelaxation. We describe the reflectance and PL properties using the model that\na cavity photon couples to a one-exciton state delocalized over nonuniformly\norientated NPLs. This model contributes to an intuitive and quantitative\nunderstanding of the microcavity containing colloidal NPLs."
    },
    {
        "anchor": "Structural Dynamics of Polymer:Non-Fullerene Organic Solar Cell Blends:\n  A Neutron Spectroscopy Perspective: Organic solar cells (OSCs) based on ADA-type (acceptor-donor-acceptor)\nnon-fullerene acceptors (NFAs) exhibit improved power conversion efficiency\n(PCE) compared to the conventional fullerene-based analogues. The\noptoelectronic properties of OSC active layer blends are correlated to their\nunderlying structural dynamics and therefore influence the device performance.\nUsing synergistically different neutron spectroscopy techniques, we studied the\ndynamics of binary and ternary blends made of the NFAs O-IDTBR and O-IDFBR and\nthe regioregular donor polymer P3HT. Deuteration was considered for a contrast\nvariation purpose. In addition to shedding light on the miscibilty and alloying\ncharacters of the blends, a main outcome of this work is the evidenced similar\ndynamical response of the blend components. This finding is in contrast with\nour previous neutron spectroscopy and molecular dynamics studies of the\nfullerene-based blend P3HT:PCBM, where we highlighted distinct behaviors of\nP3HT and PCBM in terms of the vitrification/frustration of P3HT and the\nplasticization of PCBM by P3HT upon blending. Alike P3HT vitrification is not\npresently observed. The absence or the weak vitrification evidenced here is in\nline with recent reports and is likely related to the improved PCE exhibited by\nthe ADA-type NFA-based OSCs.",
        "positive": "Ligand field parameters and the ground state of Fe(II) phthalocyanine: A judicious analysis of previously published experimental data leads one to\nconclude that the ground state of iron(II) phthalocyanine is an orbitally\ndegenerate spin triplet $a_{1g}^2 e_g^{\\uparrow\\downarrow\\uparrow}\nb_{2g}^{\\uparrow}$ ($^3E_g$). The ligand field parameters, in relation to\nRacah's $C$, are approximately as follows: $B_{20}/C=0.84$, $B_{40}/C=0.0074$.\nThe uniqueness of this result is demonstrated by means of a special diagram in\nthe $B_{20}/C-B_{40}/C$ plane (under additional conditions that\n$B_{44}/B_{40}=35/3$ and $B/C=0.227$). The system is in a strong-ligand-field\nregime, which enables the use of single-determinant techniques corrected for\ncorrelations within the 3d shell of Fe."
    },
    {
        "anchor": "Analytical and Experimental Study of X-ray Absorption Coefficients of\n  Material by Abel's Inversion: The hard x-ray gamma-ray absorption by cylindrically symmetric U-238 test\nobjects is studied by means of gamma-ray transmission measurements. To make a\nprecise comparison between the theoretically modelled values and the absorption\ncoefficients calculated from the experimental data, we have developed a highly\naccurate numerical code based on a new solution of Abel's integral equation. It\nis shown that progressive filtering, surface reflections by Compton scattering,\nand the enhanced backscattering due to impurities can explain much of the\nobserved discrepancy. We also discuss optimal experimental conditions with\nregard to the feasibility of quantitative radiography for gamma-ray\ndiagnostics.",
        "positive": "Anti-polar state in BiFeO3/NdFeO3 superlattices: Antiferroelectrics are promising materials for high energy density capacitors\nand the search for environmentally-friendly and efficient systems is actively\npursued. An elegant strategy to create and design new (anti)ferroic system\nrelies on the use of nanoscale superlattices. We report here the use of such\nstrategy and the fabrication of nanoscale BiFeO3/NdFeO3 superlattices and in\ndepth characterization using high resolution X-ray diffraction and Transmission\nElectron Microscopy. The structural analysis at atomic scale demonstrates that\nsuch superlattices host anti-polar ordering most likely described by an\nantiferroelectric-like Pbnm symmetry. Temperature dependence of anti-polar\nstate and structural transition further hint that the stability of the\nanti-polar state is controlled by the BiFeO3 layer thickness within the\nstacking and, in a more moderate way, by interlayer strain. Discovery of such\npolar arrangement in superlattices and the possible generalization to the whole\nrare-earth family pave the way to new platforms for energy storage application\nas well as nano-electronic devices."
    },
    {
        "anchor": "Structural and magnetic properties of Co-N thin films deposited using\n  magnetron sputtering at 523 K: In this work, we studied cobalt nitride (Co-N) thin films deposited using a\ndc magnetron sputtering method at a substrate temperature (\\Ts) of 523\\,K. We\nfind that independent of the reactive gas flow (\\pn) used during sputtering,\nthe phases of Co-N formed at this temperature seems to be identical having N\n\\pat~$\\sim$5. This is contrary to Co-N phases formed at lower \\Ts. For\n\\Ts$\\sim$300\\,K, an evolution of Co-N phases starting from\nCo(N)$\\rightarrow$\\tcn$\\rightarrow$Co$_3$N$\\rightarrow$CoN can be seen as \\pn\nincreases to 100\\p, whereas when the substrate temperature increases to 523\\,K,\nthe phase formed is a mixture of Co and \\tcn, independent of the {\\pn} used\nduring sputtering. We used x-ray diffraction (XRD) to probe long range\nordering, x-ray absorption spectroscopy (XAS) at Co absorption edge for the\nlocal structure, Magneto-optical Kerr e ffect (MOKE) and polarized neutron\nreflectivity (PNR) to measure the magnetization of samples. Quantification of N\n\\pat~was done using secondary ion mass spectroscopy (SIMS). Measurements\nsuggest that the magnetic moment of Co-N samples deposited at 523\\,K is\nslightly higher than the bulk Co moment and does not get affected with the\n\\pn~used for reactive sputtering. Our results provide an important insight\nabout the phase formation of Co-N thin films which is discussed in this work.",
        "positive": "Bandgap engineering in an epitaxial two-dimensional honeycomb\n  Si$_{6-x}$Ge$_x$ alloy: In this Letter, we demonstrate that it is possible to form a two-dimensional\n(2D) silicene-like Si$_5$Ge compound by replacing the Si atoms occupying on-top\nsites in the planar-like structure of epitaxial silicene on ZrB$_2$(0001) by\ndeposited Ge atoms. For coverages below 1/6 ML, the Ge deposition gives rise to\na Si$_{6-x}$Ge$_{x}$ alloy (with $x$ between 0 and 1) in which the on-top sites\nare randomly occupied by Si or Ge atoms. The progressive increase of the\nvalence band maximum with $x$ observed experimentally originates from a\nselective charge transfer from Ge atoms to Si atoms. These achievements provide\nevidence for the possibility of engineering the bandgap in 2D SiGe alloys in a\nway that is similar for their bulk counterpart."
    },
    {
        "anchor": "Sharp bends in photonic crystal waveguides as nonlinear Fano resonators: We demonstrate that high transmission through sharp bends in photonic crystal\nwaveguides can be described by a simple model of the Fano resonance where the\nwaveguide bend plays a role of a specific localized defect. We derive effective\ndiscrete equations for two types of the waveguide bends in two-dimensional\nphotonic crystals and obtain exact analytical solutions for the resonant\ntransmission and reflection. This approach allows us to get a deeper insight\ninto the physics of resonant transmission, and it is also useful for the study\nand design of power-dependent transmission through the waveguide bends with\nembedded nonlinear defects.",
        "positive": "Theoretical Analysis of a Two-Dimensional Metallic/Semiconducting\n  Transition-Metal Dichalcogenide NbS2//WSe2 Hybrid Interface: We report a first-principle theoretical study of a monolayer-thick lateral\nheterostructure (LH) joining two different transition metal dichalcogenides\n(TMDC): NbS2 and WSe2. The NbS2//WSe2 LH can be considered a prototypical\nexample of a conducting(NbS2)/semiconducting(WSe2) two-dimensional (2D) hybrid\nheterojunction. We first generate and validate realistic atomistic models of\nthe NbS2//WSe2 LH, derive their band structure and subject it to a fragment\ndecomposition and electrostatic potential analysis to extract a simple but\nquantitative model of this interfacial system. Stoichiometric fluctuations\nmodels are also investigated and found not to alter the qualitative picture. We\nthen conduct electron transport simulations analyze them via band alignment\nanalysis. We conclude that the NbS2//WSe2 LH appears as a robust seamless\nin-plane 2D modular junction for potential use in opto-electronic devices going\nbeyond the present miniaturization technology."
    },
    {
        "anchor": "Synthesis, characterization, and application of carbon cubes: Carbon nanotubes (CNTs) have attracted increasing attention because of their\nunique structural, mechanical, and electronic properties. Surface chemistry\nmodifications are also useful and critical to manipulate the adsorptive\nproperties of CNTs and develop their potential of environmental application.\nTherefore, the main objectives of this study were to investigate the optimal\nsynthesis methods or characteristics identification of multiwall CNTs (MWCNTs)\nand the environmental application of lead ions adsorptive removal by CNTs.\nExperimentally, the MWCNTs of well-graphited walls were obtained with reductive\npotassium metals of catalytic hexachlorobenzene-thermal routes in the presence\nof Co/Ni catalyst precursors at 503-623 K for 8- 12 hr. The diameters of MWCNTs\nranged of 30-100 nm by TEM microphotos. In addition, fine structures or surface\nchemical modification of MWCNTs or Co/Ni precursors were further identified by\nEDS, XRPD, X-ray absorption near edge structural (XANES) or extended Xray\nabsorption fine structural (EXAFS) spectroscopy. 1.",
        "positive": "Comprehensive study on band-gap variations in $sp^3$-bonded\n  semiconductors: roles of electronic states floating in internal space: We have performed electronic structure calculations to explore the band-gap\ndependence on polytypes for $sp^3$-bonded semiconducting materials, i.e., SiC,\nAlN, BN, GaN, Si, and diamond. In this comprehensive study, we have found that\nband-gap variation depending on polytypes is common in $sp^3$-bonded\nsemiconductors; SiC, AlN, and BN exhibit smallest band gaps in $3C$ structure,\nwhereas diamond does in $2H$ structure. We have also clarified that the\nmicroscopic mechanism of the band-gap variations is attributed to peculiar\nelectron states $floating$ in internal channel space at the conduction-band\nminimum (CBM), and that internal channel length and the electro-static\npotential in channel affect the energy level of CBM."
    },
    {
        "anchor": "Rungs 1 to 4 of DFT Jacob's ladder: extensive test on the lattice\n  constant, bulk modulus, and cohesive energy of solids: A large panel of old and recently proposed exchange-correlation functionals\nbelonging to rungs 1 to 4 of Jacob's ladder of density functional theory are\ntested (with and without a dispersion correction term) for the calculation of\nthe lattice constant, bulk modulus, and cohesive energy of solids. Particular\nattention will be paid to the functionals MGGA_MS2 [J. Sun et al., J. Chem.\nPhys. 138, 044113 (2013)], mBEEF [J. Wellendorff et al., J. Chem. Phys. 140,\n144107 (2014)], and SCAN [J. Sun et al., Phys. Rev. Lett. 115, 036402 (2015)]\nthat are approximations of the meta-generalized gradient type and were\ndeveloped with the goal to be universally good. Another goal is also to\ndetermine for which semilocal functionals and groups of solids it is beneficial\n(or not necessary) to use the Hartree-Fock exchange or a dispersion correction\nterm.",
        "positive": "Interplay between magnetism and charge instabilities in layered\n  NbSe$_{2}$: Using ab initio methods based on density functional theory, the electronic\nand magnetic structure of layered hexagonal NbSe$_{2}$ is studied. In the case\nof single-layer NbSe$_{2}$ it is found that, for all the functionals\nconsidered, the magnetic solution is lower in energy than the non-magnetic\nsolution. The magnetic ground-state is ferrimagnetic with a magnetic moment of\n1.09 $\\mu_{B}$ at the Nb atoms and a magnetic moment of 0.05 $\\mu_{B}$, in the\nopposite direction, at the Se atoms. Our calculations show that single-layer\nNbSe$_{2}$ does not display a charge density wave instability unless a graphene\nlayer is considered as a substrate. Then, two kinds of 3$\\times$3 charge\ndensity waves are found, which are observed in our STM experiments. This\nsuggest that the driving force of charge instabilities in NbSe$_{2}$ differ in\nbulk and in the single-layer limit. Our work sets magnetism into play in this\nhighly-correlated 2D material, which is crucial to understand the formation\nmechanisms of 2D superconductivity and charge density wave order."
    },
    {
        "anchor": "Insulator-to-metal transition of SrTiO3:Nb single crystal surfaces\n  induced by Ar+ bombardment: In this paper, the effect of Ar+ bombardment of SrTiO3:Nb surface layers is\ninvestigated on the macro- and nanoscale using surface-sensitive methods. After\nbombardment, the stoichiometry and electronic structure are changed distinctly\nleading to an insulator-to-metal transition related to the change of the Ti \"d\"\nelectron from d0 to d1 and d2. During bombardment, conducting islands are\nformed on the surface. The induced metallic state is not stable and can be\nreversed due to a redox process by external oxidation and even by\nself-reoxidation upon heating the sample to temperatures of 300{\\deg}C.",
        "positive": "Electronic, vibrational, and thermodynamic properties of ZnS (zincblende\n  and rocksalt structure): We have measured the specific heat of zincblende ZnS for several isotopic\ncompositions and over a broad temperature range (3 to 1100 K). We have compared\nthese results with calculations based on ab initio electronic band structures,\nperformed using both LDA and GGA exchange- correlation functionals. We have\ncompared the lattice dynamics obtained in this manner with experimental data\nand have calculated the one-phonon and two-phonon densities of states. We have\nalso calculated mode Grueneisen parameters at a number of high symmetry points\nof the Brillouin zone. The electronic part of our calculations has been used to\ninvestigate the effect of the 3d core electrons of zinc on the spin-orbit\nsplitting of the top valence bands. The effect of these core electrons on the\nband structure of the rock salt modification of ZnS is also discussed."
    },
    {
        "anchor": "Emission engineering in monolithically integrated silicon nitride\n  microring resonators: Monolithic integration of solid-state color centers with photonic elements of\nthe same material is a promising approach to overcome the constraints of\nfabrication complexity and coupling losses in traditional hybrid integration\napproaches. A wide band-gap, low-loss silicon nitride (SiN) platform is a\nmature technology, having CMOS compatibility, widely used in hybrid integrated\nphotonics and optoelectronics. However, it has been shown that certain growth\nconditions enable the SiN material to host color centers, whose origin is\ncurrently under investigation. In this work, we have engineered a novel\ntechnique for the efficient coupling of these intrinsic emitters into the\nwhispering gallery modes (WGMs) of the SiN microring cavity -- which has not\nbeen explored previously. We have engineered a subwavelength-sized notch into\nthe rim of the SiN microring structure, to optimize the collection efficiency\nof the cavity-coupled enhanced photoluminescence (PL) spectra at room\ntemperature. The platform presented in this work will enable the development of\nmonolithic integration of color centers with nanophotonic elements for\napplication to quantum photonic technologies.",
        "positive": "First-principles predicted low-energy structures of NaSc(BH4)4: According to previous interpretations of experimental data, sodium-scandium\ndouble-cation borohydride NaSc(BH$_4$)$_4$ crystallizes in the crystallographic\nspace group $Cmcm$ where each sodium (scandium) atom is surrounded by six\nscandium (sodium) atoms. A careful investigation of this phase based on\n\\textit{ab initio} calculations indicates that the structure is dynamically\nunstable and gives rise to an energetically and dynamically more favorable\nphase with $C222_1$ symmetry and nearly identical x-ray diffraction pattern. By\nadditionally performing extensive structural searches with the minima-hopping\nmethod we discover a class of new low-energy structures exhibiting a novel\nstructural motif in which each sodium (scandium) atom is surrounded by four\nscandium (sodium) atoms arranged at the corners of either a rectangle with\nnearly equal sides or a tetrahedron. These new phases are all predicted to be\ninsulators with band gaps of $7.9-8.2$ eV. Finally, we estimate the influence\nof these structures on the hydrogen-storage performance of NaSc(BH$_4$)$_4$."
    },
    {
        "anchor": "Diverse Magnetic Quantization in Bilayer Silicene: The generalized tight-binding model is developed to investigate the rich and\nunique electronic properties of AB-bt (bottom-top) bilayer silicene under\nuniform perpendicular electric and magnetic fields. The first pair of\nconduction and valence bands, with an observable energy gap, displays unusual\nenergy dispersions. Each group of conduction/valence Landau levels (LLs) is\nfurther classified into four subgroups, that is, there exist the sublattice-\nand spin-dominated LL subgroups. The magnetic-field-dependent LL energy spectra\nexhibit irregular behavior corresponding to the critical points of the band\nstructure. Moreover, the electric field can induce many LL anti-crossings. The\nmain features of the LLs are uncovered with many van Hove singularities in the\ndensity-of-states and non-uniform delta-function-like peaks in the\nmagneto-absorption spectra. The feature-rich magnetic quantization directly\nreflects the geometric symmetries, intra-layer and inter-layer atomic\ninteractions, spin-orbital couplings, and the field effects. The results of\nthis work can be applied to novel designs of $Si$-based nano-electronics and\nnano-devices with enhanced mobilities.",
        "positive": "Diffusion of Be in gallium nitride: Experiment and modelling: Diffusion mechanism of beryllium in gallium nitride was investigated by\nanalyzing temperature-dependent diffusion profiles from an infinite source.\nBeryllium atoms were implanted into a high structural quality gallium nitride\nlayer crystallized by halide vapor phase epitaxy on an ammonothermal gallium\nnitride substrate. Post-implantation annealing was performed at different\ntemperatures, between 1000{\\deg}C and 1400{\\deg}C, under high nitrogen\npressure. Beryllium profiles were analyzed in the as-implanted and annealed\nsamples by secondary ion mass spectrometry. It was shown that the diffusion of\nthe dopant results from the combination of two mechanisms: rapid interstitial\nand slow interstitial-substitutional diffusion. The pre-exponential factor as\nwell as activation energy for both diffusion paths were determined. Moreover,\nfrom the characteristic features of beryllium depth profiles, the formation\nenergies of gallium vacancy and beryllium in interstitial position were\ncalculated and compared to the theoretical values."
    },
    {
        "anchor": "Elastic and structural instability of cubic Sn3N4 and C3N4 under\n  pressure: We use in-situ high pressure angle dispersive x-ray diffraction measurements\nto determine the equation of state of cubic tin nitride Sn3N4 under pressure up\nto about 26 GPa. While we find no evidence for any structural phase transition,\nour estimate of the bulk modulus (B) is 145 GPa, much lower than the earlier\ntheoretical estimates and that of other group IV-nitrides. We corroborate and\nunderstand these results with complementary first-principles analysis of\nstructural, elastic and vibrational properties of group IV-nitrides, and\npredict a structural transition of Sn3N4 at a higher pressure of 88 GPa\ncompared to earlier predictions of 40 GPa. Our comparative analysis of cubic\nnitrides shows that bulk modulus of cubic C3N4 is the highest (379 GPa) while\nit is structurally unstable and should not exist at ambient conditions.",
        "positive": "Epitaxial fabrication of AgTe monolayer on Ag(111) and the sequential\n  growth of Te film: Transition-metal chalcogenides (TMCs) materials have attracted increasing\ninterest both for fundamental research and industrial applications. Among all\nthese materials, two-dimensional (2D) compounds with honeycomb-like structure\npossess exotic electronic structures. Here, we report a systematic study of TMC\nmonolayer AgTe fabricated by direct depositing Te on the surface of Ag(111) and\nannealing. Few intrinsic defects are observed and studied by scanning tunneling\nmicroscopy, indicating that there are two kinds of AgTe domains and they can\nform gliding twin-boundary. Then, the monolayer AgTe can serve as the template\nfor the following growth of Te film. Meanwhile, some Te atoms are observed in\nthe form of chains on the top of the bottom Te film. Our findings in this work\nmight provide insightful guide for the epitaxial growth of 2D materials for\nstudy of novel physical properties and for future quantum devices."
    },
    {
        "anchor": "Why In2O3 Can Make 0.7 nm Atomic Layer Thin Transistors?: In this work, we demonstrate enhancement-mode field-effect transistors by\natomic-layer-deposited (ALD) amorphous In2O3 channel with thickness down to 0.7\nnm. Thickness is found to be critical on the materials and electron transport\nof In2O3. Controllable thickness of In2O3 at atomic scale enables the design of\nsufficient 2D carrier density in the In2O3 channel integrated with the\nconventional dielectric. The threshold voltage and channel carrier density are\nfound to be considerably tuned by channel thickness. Such phenomenon is\nunderstood by the trap neutral level (TNL) model where the Fermi-level tends to\nalign deeply inside the conduction band of In2O3 and can be modulated to the\nbandgap in atomic layer thin In2O3 due to quantum confinement effect, which is\nconfirmed by density function theory (DFT) calculation. The demonstration of\nenhancement-mode amorphous In2O3 transistors suggests In2O3 is a competitive\nchannel material for back-end-of-line (BEOL) compatible transistors and\nmonolithic 3D integration applications.",
        "positive": "An indirect magnetic approach for determining entropy change in\n  first-order magnetocaloric materials: Taking into account the phase fraction during transition for the first-order\nmagnetocaloric materials, an improved isothermal entropy change determination\nhas been put forward based on the Clausius-Clapeyron (CC) equation. It was\nfound that the isothermal entropy change value evaluated by our method is in\nexcellent agreement with those determined from the Maxwell-relation (MR) for\nNi-Mn-Sn Heusler alloys, which usually presents a weak field-induced phase\ntransforming behavior. In comparison with MR, this method could give rise to a\nfavorable result derived from few thermomagnetic measurements. More\nimportantly, we can eliminate the isothermal entropy change overestimation\nderived from MR, which always exists in the cases of Ni-Co-Mn-In and MnAs\nsystems with a prominent field-induced transition. These results confirmed that\nsuch a CC-equation-based method is quite practical and superior to the MR-based\nones in eliminating the spurious spike and reducing measuring cost."
    },
    {
        "anchor": "Direct Visualization and Manipulation of Tunable Quantum Well State in\n  Semiconducting Nb2SiTe4: Quantum well states (QWSs) can form at the surface or interfaces of materials\nwith confinement potential. They have broad applications in electronic and\noptical devices such as high mobility electron transistor, photodetector and\nquantum well laser. The properties of the QWSs are usually the key factors for\nthe performance of the devices. However, direct visualization and manipulation\nof such states are in general challenging. In this work, by using\nangle-resolved photoemission spectroscopy (ARPES) and scanning tunneling\nmicroscopy/spectroscopy (STM/STS), we directly probe the QWSs generated on the\nvacuum interface of a narrow band gap semiconductor Nb2SiTe4. Interestingly,\nthe position and splitting of QWSs could be easily manipulated via potassium\n(K) dosage onto the sample surface. Our results suggest Nb2SiTe4 to be an\nintriguing semiconductor system to study and engineer the QWSs, which has great\npotential in device applications.",
        "positive": "What is the stable atomic structure of NiTi austenite?: Nitinol (NiTi), the most widely used shape-memory alloy, exhibits an\naustenite phase that has yet to be identified. The usually assumed austenite\nstructure is cubic B2, which has imaginary phonon modes, hence it is unstable.\nWe suggest a stable austenite structure that on average has B2 symmetry\n(observed by X-ray and neutron diffraction), but exhibits finite atomic\ndisplacements from the ideal B2 sites. The proposed structure has a phonon\nspectrum that agrees with that from neutron scattering, has diffraction spectra\nin agreement with XRD, and has an energy relative to the ground state that\nagrees with calorimetry data."
    },
    {
        "anchor": "Resonant magnetic X-ray scattering spectra in SDW Cr -- ab initio study\n  -----: Using ab-initio band structure calculation based on the local density\napproximation, Cr K-edge resonant X-ray magnetic scattering spectra are\nanalyzed in the spin density wave (SDW) state of chromium. We perform band\nstructure calculation, assuming an ideal bcc lattice structure with the lattice\nconstant observed at the spin-flip temperature T_{SF} and a commensurate SDW\nstate with the propagation vector close to the observed value at T_{SF}. Taking\naccount of the spin-orbit interaction, we obtain the orbital moment on each Cr\nsite induced in proportion to the local spin moment, which is quite small, at\nmost a tenth of those in nickel or iron. In spite of the tiny 3d orbital\nmoment, the orbital polarization is found to have large fluctuations as a\nfunction of energy. We obtain the scattering intensity at the Cr K-edge on the\nSDW magnetic Bragg spot, which shows resonant enhancement in good agreement\nwith the experiment. The 3d orbital polarization is found to be highly\ncorrelated with the intensity of the resonant main peak, indicating that the 4p\norbital polarization is mainly induced by the 3d orbital polarization through\nthe p-d hybridization.",
        "positive": "Defect tolerant device geometries: The term defect tolerance is widely used in literature to describe materials\nsuch as lead-halides which exhibit long non-radiative lifetimes of carriers\ndespite possessing a large concentration of point defects. Studies on defect\ntolerance of materials mostly look at the properties of the host material\nand/or the chemical nature of defects that affect the capture coefficients of\ndefects. However, the recombination activity of a defect is not only a function\nof its capture coefficients alone but are also dependent on the electrostatics\nand the design of the layer stack of a photovoltaic device. Here we study the\ninfluence of device geometry on defect tolerance by combining calculations of\ncapture coefficients with device simulations. We derive generic device design\nprinciples which can inhibit recombination inside a photovoltaic device for a\ngiven set of capture coefficients based on the idea of slowing down the slower\nof the two processes (electron and hole capture) even further by modifying\nelectron and hole injection into the absorber layer. We use the material\nparameters and typical p-i-n device geometry representing methylammonium lead\nhalide perovskites solar cells to illustrate the application of our generic\ndesign principles to improve specific devices ."
    },
    {
        "anchor": "Exciton-phonon coupling in MoSe2 monolayers: We study experimentally and theoretically the exciton-phonon interaction in\nMoSe2 monolayers encapsulated in hexagonal BN, which has an important impact on\nboth optical absorption and emission processes. The exciton transition\nlinewidth down to 1 meV at low temperatures makes it possible to observe high\nenergy tails in absorption and emission extending over several meV, not masked\nby inhomogeneous broadening. We develop an analytical theory of the\nexciton-phonon interaction accounting for the deformation potential induced by\nthe longitudinal acoustic phonons, which plays an important role in exciton\nformation. The theory allows fitting absorption and emission spectra and\npermits estimating the deformation potential in MoSe2 monolayers. We underline\nthe reasons why exciton-phonon coupling is much stronger in two-dimensional\ntransition metal dichalcodenides as compared to conventional quantum well\nstructures. The importance of exciton-phonon interactions is further\nhighlighted by the observation of a multitude of Raman features in the\nphotoluminescence excitation experiments.",
        "positive": "Reciprocal space study of Heisenberg exchange interactions in\n  ferromagnetic metals: The modern quantum theory of magnetism in solids is getting commonly derived\nusing Green's functions formalism. The popularity draws itself from remarkable\nopportunities to capture the microscopic landscape of exchange interactions,\nstarting from a tight-binding representation of the electronic structure.\nIndeed, the conventional method of infinitesimal spin rotations, considered in\nterms of local force theorem, opens vast prospects of investigations regarding\nthe magnetic environment, as well as pairwise atomic couplings. However, this\ntheoretical concept practically does not devoid of intrinsic inconsistencies.\nIn particular, naturally expected correspondence between single and pairwise\ninfinitesimal spin rotations is being numerically revealed to diverge. In this\nwork, we elaborate this question on the model example and canonical case of bcc\niron. Our analytical derivations discovered the principal preference of on-site\nmagnetic precursors if the compositions of individual atomic interactions are\nin focus. The problem of extremely slow or even absent spatial convergence\nwhile considering metallic compounds was solved by suggesting the original\ntechnique, based on reciprocal space framework. Using fundamental Fourier\ntransform-inspired interconnection between suggested technique and traditional\nspatial representation, we shed light on symmetry breaking in bcc Fe on the\nlevel of orbitally decomposed total exchange surrounding."
    },
    {
        "anchor": "Spin State Disproportionation in Insulating Ferromagnetic LaCoO3\n  Epitaxial Thin Films: The origin of insulating ferromagnetism in epitaxial LaCoO3 films under\ntensile strain remains elusive despite extensive research efforts have been\ndevoted. Surprisingly, the spin state of its Co ions, the main parameter of its\nferromagnetism, is still to be determined. Here, we have systematically\ninvestigated the spin state in epitaxial LaCoO3 thin films to clarify the\nmechanism of strain induced ferromagnetism using element-specific x-ray\nabsorption spectroscopy and dichroism. Combining with the configuration\ninteraction cluster calculations, we unambiguously demonstrate that Co3+ in\nLaCoO3 films under compressive strain (on LaAlO3 substrate) are practically a\nlow spin state, whereas Co3+ in LaCoO3 films under tensile strain (on SrTiO3\nsubstrate) have mixed high spin and low spin states with a ratio close to 1:3.\nFrom the identification of this spin state ratio, we infer that the dark strips\nobserved by high-resolution scanning transmission electron microscopy indicate\nthe position of Co3+ high spin state, i.e., an observation of a spin state\ndisproportionation in tensile-strained LaCoO3 films. This consequently explains\nthe nature of ferromagnetism in LaCoO3 films.",
        "positive": "A Comprehensive Model of Snow Crystal Faceting: Crystal faceting can emerge via two broad physical mechanisms: anisotropic\nattachment kinetics on growing crystals and anisotropic surface energies on\nnear-equilibrium crystals. For the case of the ice/vapor system, anisotropic\nattachment kinetics is the dominant faceting mechanism, while the possible\noccurrence of equilibrium faceting has been debated for many decades. In this\ninvestigation we examine ice/vapor faceting at low supersaturations over the\ntemperature range -15C<T<0C, where evidence of a roughening transition has been\npreviously reported. Our findings indicate that a comprehensive attachment\nkinetics model can explain all the experimental data to date, while assuming an\nessentially isotropic surface energy (which is supported by other\nconsiderations). Specifically, our kinetic model naturally explains the\nobserved disappearance of prism faceting on slowly growing ice crystals in\nvacuum at T>-2C, thus suggesting that snow crystal faceting is caused by\nanisotropic attachment kinetics even at extremely slow growth rates."
    },
    {
        "anchor": "Unravelling the Local Crystallographic Structure of Ferromagnetic\n  Ga$_y$Fe$_{4-y}$N Nanocrystals Embedded in GaN: In the Fe-doped GaN phase-separated magnetic semiconductor GaFeN, the\npresence of embedded Ga$_y$Fe$_{4-y}$N nanocrystals determines the magnetic\nproperties of the system. Here, through a combination of anomalous x-ray\ndiffraction and diffraction anomalous fine structure, the local structure of Ga\nin self-assembled face-centered cubic (fcc) Ga$_y$Fe$_{4-y}$N nanocrystals\nembedded in wurtzite GaN thin layers is investigated in order to shed light\nonto the correlation between fabrication parameters, local structural\narrangement and overall magnetic properties of the material system. It is\nfound, that by adjusting the growth parameters and thus, the crystallographic\nsurroundings, the Ga atoms can be induced to incorporate into 3$c$ positions at\nthe faces of the fcc crystal lattice, reaching a maximum occupancy of 30\\%. The\nmagnetic response of the embedded nanocrystals is ferromagnetic with Curie\ntemperature increasing from 450\\,K to 500\\,K with the Ga occupation. These\nresults demonstrate the outstanding potential of the employed experimental\nprotocol for unravelling the local structure of magnetic multi-phase systems,\neven when embedded in a matrix containing the same element under investigation.",
        "positive": "Towards overcoming data scarcity in materials science: unifying models\n  and datasets with a mixture of experts framework: While machine learning has emerged in recent years as a useful tool for rapid\nprediction of materials properties, generating sufficient data to reliably\ntrain models without overfitting is still impractical for many applications.\nTowards overcoming this limitation, we present a general framework for\nleveraging complementary information across different models and datasets for\naccurate prediction of data scarce materials properties. Our approach, based on\na machine learning paradigm called mixture of experts, outperforms pairwise\ntransfer learning on 16 of 19 materials property regression tasks, performing\ncomparably on the remaining three. Unlike pairwise transfer learning, our\nframework automatically learns to combine information from multiple source\ntasks in a single training run, alleviating the need for brute-force\nexperiments to determine which source task to transfer from. The approach also\nprovides an interpretable, model-agnostic, and scalable mechanism to transfer\ninformation from an arbitrary number of models and datasets to any downstream\nproperty prediction task. We anticipate the performance of our framework will\nfurther improve as better model architectures, new pre-training tasks, and\nlarger materials datasets are developed by the community."
    },
    {
        "anchor": "Higher-order magnetic anisotropy in soft-hard magnetic materials: We have computationally studied the properties of higher-order magnetic\nanisotropy constants in an L10/A1-FePt coreshell system which is characterized\nby a strong second-order 2-ion Fe-Pt anisotropy component. We show that the\ncoreshell structure induces an unexpected fourth-order anisotropy constant K2\nthe magnitude of which varies non-monotonically with the core-size ratio R\nreaching a peak at R = 0.50. Furthermore, we find that K2 scales with the\nnormalized magnetization by (M/Ms)^2.2 at temperatures below the Curie\ntemperature - a remarkable deviation from the established Callen-Callen theory\nwhich instead predicts a scaling exponent of 10. We construct an analytic model\nwhich demonstrates K2 arises from the canting of the core and shell\nmagnetization, and successfully reproduces and justifies the scaling exponent\nobtained from numerical simulation.",
        "positive": "Spin wave dispersion based on the quasiparticle self-consistent $GW$\n  method: NiO, MnO and $\u03b1$-MnAs: We present spin wave dispersions in MnO, NiO, and $\\alpha$-MnAs based on the\nquasiparticle self-consistent $GW$ method (\\qsgw), which determines an optimum\nquasiparticle picture. For MnO and NiO, \\qsgw results are in rather good\nagreement with experiments, in contrast to the LDA and LDA+U description. For\n$\\alpha$-MnAs, we find a collinear ferromagnetic ground state in \\qsgw, while\nthis phase is unstable in the LDA."
    },
    {
        "anchor": "System-adapted correlation energy density functionals from effective\n  pair interactions: We present and discuss some ideas concerning an ``average-pair-density\nfunctional theory'', in which the ground-state energy of a many-electron system\nis rewritten as a functional of the spherically and system-averaged pair\ndensity. These ideas are further clarified with simple physical examples. We\nthen show that the proposed formalism can be combined with density functional\ntheory to build system-adapted correlation energy functionals. A simple\napproximation for the unknown effective electron-electron interaction that\nenters in this combined approach is described, and results for the He series\nand for the uniform electron gas are briefly reviewed.",
        "positive": "Magnetism trends in doped Ce-Cu intermetallics in the vicinity of\n  quantum criticality: realistic Kondo lattice models based on dynamical\n  mean-field theory: The quantum critical point (QCP) in the archetypical heavy-fermion compound\nCeCu$_6$ doped by Au is described, accounting for the localized $4f$-electron\nof Ce, using realistic electronic structure calculations combined with\ndynamical mean-field theory (DMFT). Magnetism trends in\nCe(Cu$_{1-\\epsilon}$Au$_\\epsilon$)$_6$ are compared with those in Co-doped\nCeCu$_{5}$, which resides on the non-ferromagnetic side of the composition\nspace of one of the earliest rare-earth permanent magnet compounds,\nCe(Co,Cu)$_5$. The construction of a realistic Doniach phase diagram shows that\nthe system crosses over a magnetic quantum critical point in the Kondo lattice\nin $0.2<x<0.4$ of Ce(Cu$_{1-x}$Co$_x$)$_5$. Comparison between Au-doped\nCeCu$_6$ and Co-doped CeCu$_5$ reveals that the swept region in the vicinity of\nQCP for the latter thoroughly covers that of the former. The implications of\nthese trends on the coercivity of the bulk rare-earth permanent magnets are\ndiscussed."
    },
    {
        "anchor": "Contribution to Viscosity from the Structural Relaxation via the Atomic\n  Scale Green-Kubo Stress Correlation Function: We studied the connection between the structural relaxation and viscosity for\na binary model of repulsive particles in the supercooled liquid regime. The\nused approach is based on the decomposition of the macroscopic Green-Kubo\nstress correlation function into the correlation functions between the atomic\nlevel stresses. Previously we used the approach to study an iron-like single\ncomponent system of particles. The role of vibrational motion has been\naddressed through the demonstration of the relationship between viscosity and\nthe shear waves propagating over large distances. In our previous\nconsiderations, however, we did not discuss the role of the structural\nrelaxation. Here we suggest that the contribution to viscosity from the\nstructural relaxation can be taken into account through the consideration of\nthe contribution from the atomic stress auto-correlation term only. This\nconclusion, however, does not mean that only the auto-correlation term\nrepresents the contribution to viscosity from the structural relaxation.\nPreviously the role of the structural relaxation for viscosity has been\naddressed through the considerations of the transitions between inherent\nstructures and within the mode-coupling theory by other authors. In the present\nwork, we study the structural relaxation through the considerations of the\nparent liquid and the atomic level stress correlations in it. The comparison\nwith the results obtained on the inherent structures also is made. Our results\nsuggest that in the supercooled liquid regime the vibrational contribution to\nviscosity extends over the times which are much larger than the Einstein's\nvibrational period and much larger than the times which it takes for the shear\nwaves to propagate over the model systems. Besides addressing the atomic level\nshear stress correlations, we also studied correlations between the atomic\nlevel pressure elements.",
        "positive": "Dirac fermions in Fe ultra-thin film: We show the existence of massive Dirac fermions in electronic band structures\nof a few Fe atomic layers with perpendicular magnetization. Based on a tight\nbinding model fitted to ab-initio band structure, we observe four distinct\nmassive Dirac fermions near the Fermi level, which result from atomic\nspin-orbit coupling of Fe and a band inversion between Fe $4s$-$3d_{x^2-y^2}$\nhybrid orbital band and $3d_{xy}$ orbital band. These lead to a valence band\nwith finite Chern integer (+2) and chiral edge modes near the Fermi level. When\nthe chemical potential is set inside the Dirac gap by carrier doping, the Hall\nconductivity exhibits a plateau-like structure with quantized value\n$2\\frac{e^2}{h}$, and orbital magnetization shows a prominent increase, latter\nof which is mostly due to chiral orbital motion of electrons along the edge\nmodes. We discuss the stability of the Dirac fermions in Fe(001) monolayer on\nMgO(001) substrate and Fe(001) bilayer case."
    },
    {
        "anchor": "Continuous degeneracy of the fcc kagome lattice with magnetic dipolar\n  interactions: Results are presented on analytic and computational analyses of the spin\nstates associated with a 3D fcc lattice composed of ABC stacked kagome planes\nof magnetic ions with only long-range dipole-dipole interactions. Extending\nprevious work on the 2D kagome system, where discrete six-fold discrete\ndegeneracy of the ground state was revealed [Holden et al. Phys. Rev. B 91,\n224425 (2015)], we show that the 3D lattice exhibits a continuous degeneracy\ncharacterized by just two spherical angles involving six sublattice spin\nvectors. Application of a Heat Bath Monte Carlo algorithm shows that thermal\nfluctuations reduce this degeneracy at very low temperature in an\norder-by-disorder process. A magnetic field applied along directions of high\nsymmetry also results in lifting the continuous degeneracy to a subset of\nstates from the original set of ground states. Metropolis Monte Carlo\nsimulation results are also presented on the temperature and system size\ndependence of the energy, specific heat, and magnetization, providing evidence\nfor a phase transition at T $\\simeq$ 0.38 (in units of the dipole strength).\nThe results can be relevant to a class of magnetic compounds having the\nAuCu$_3$ crystal structure.",
        "positive": "Spin reorientation transition in an ultrathin Fe film on W(110) induced\n  by Dzyaloshinsky-Moriya interactions: Controlling the preferred direction of the magnetic moments is essential for\nthe design of spintronic devices based on ultrathin films and heterostructures.\nAs the film thickness or the temperature is increased, the easy anisotropy axis\nis typically reoriented from an out-of-plane direction preferred by surface and\ninterface energy contributions to an in-plane alignment favored by the volume\nanisotropy terms. We study the temperature-driven spin reorientation transition\nin two atomic layers of Fe on W(110) using well-tempered metadynamics\nsimulations based on a spin model parametrized by ab initio calculations and\nfind that the transition only takes place in the presence of the\nDzyaloshinsky--Moriya interaction (DMI). This demonstrates that the chiral DMI\ndoes not only differentiate between noncollinear spin structures of different\nrotational senses, but it also influences the magnetic orientation of collinear\nmagnetic configurations."
    },
    {
        "anchor": "Structures and Electronic States of Nickel Rich Oxides for Lithium Ion\n  Batteries: A new superstructure of layered pristine LiNiO2 (LNO) was obtained optimizing\na large supercell of the 166 space group, the one observed experimentally by\nXRD, and relaxing both cell parameters and internal positions. The crystal\nstructure shows size and charge disproportionation of the NiO6 octahedra\ninstead of the Jahn-Teller distortion. The decrease of the internal energy\nobtained with the structural optimization of the supercell relative to the same\nstructure in its primitive unit cell is much larger than the one obtained by\nrelaxing similarly dimensioned supercells of monoclinic symmetry relative to\ntheir primitive unit cells, although the monoclinic phase remains more stable.\nThe Ni-O bond length distribution of the new structure agree well with the\nexperiments. Our results show that the choice of the simulation cell is\nimportant for determining the energetics of this class of oxide materials,\nproposed for cathodes in lithium ion batteries (LIBs). We used this new\nstructure as a template for the study of the structural and electronic changes\ninduced by the delithiation and Mn for Ni cation substitution, originating the\nsolid solutions LiNiyMn(1-y)O2 (LNMO). Our results, surprisingly, agree well\nwith the existing experiments and explain observed trends better than previous\nstudies.",
        "positive": "Parallelized Hybrid Monte Carlo Simulation of Stress-Induced Texture\n  Evolution: A parallelized hybrid Monte Carlo (HMC) methodology is devised to quantify\nthe microstructural evolution of polycrystalline material under elastic\nloading. The approach combines a time explicit material point method (MPM) for\nthe mechanical stresses with a calibrated Monte Carlo (cMC) model for grain\nboundary kinetics. The computed elastic stress generates an additional driving\nforce for grain boundary migration. The paradigm is developed, tested, and\nsubsequently used to quantify the effect of elastic stress on the evolution of\ntexture in nickel polycrystals. As expected, elastic loading favors grains\nwhich appear softer with respect to the loading direction. The rate of texture\nevolution is also quantified, and an internal variable rate equation is\nconstructed which predicts the time evolution of the distribution of\norientations."
    },
    {
        "anchor": "Resonant tunneling magnetoresistance in epitaxial metal-semiconductor\n  heterostructures: We report on resonant tunneling magnetoresistance via localized states\nthrough a ZnSe semiconducting barrier which can reverse the sign of the\neffective spin polarization of tunneling electrons. Experiments performed on\nFe/ZnSe/Fe planar junctions have shown that positive, negative or even its\nsign-reversible magnetoresistance can be obtained, depending on the bias\nvoltage, the energy of localized states in the ZnSe barrier and spatial\nsymmetry. The averaging of conduction over all localized states in a junction\nunder resonant condition is strongly detrimental to the magnetoresistance.",
        "positive": "Melting and decomposition of orthorhombic B6Si under high pressure: Melting of orthorhombic boron silicide B6Si has been studied at pressures up\nto 8 GPa using in situ electrical resistivity measurements and quenching. It\nhas been found that in the 2.6-7.7 GPa range B6Si melts congruently, and the\nmelting curve exhibits negative slope of -31(2) K/GPa that points to a higher\ndensity of the melt as compared to the solid phase. At very high temperatures\nB6Si melt appears to be unstable and undergoes disproportionation into silicon\nand boron-rich silicides. The onset temperature of disproportionation strongly\ndepends on pressure, and the corresponding low-temperature boundary exhibits\nnegative slope of -92(3) K/GPa which is indicative of significant volume\ndecrease in the course of B6Si melt decomposition."
    },
    {
        "anchor": "A DFT computational design and exploration of novel direct band gap\n  silver-thallium double perovskites: Researchers have addressed the non-traditional power generation schemes as\nalternatives to the traditional fossil-fuel methods enormously since the\nscientific community has serious concerns about shortages of energy on our\nplanet for future generations. In this scenario, the innovative materials for\nphotovoltaic and thermoelectric device applications are required by addressing\ncurrent issues of instability and efficiency. Perovskites are very popular in\nthis regard particularly having higher power conversion efficiency of 25.2% in\nthe case of solar cells. In the current article, we investigated innovative\nsmall direct band gap double perovskites (elapsolite) Cs$_2$AgTlX$_6$ (X= Cl,\nBr) with a comprehensive discussion on structural, electronic, optical, and\nthermoelectric properties using a first-principles approach. The compounds\nunder investigation are found stable, efficient, and economical with alluring\noptical and thermoelectric properties. The higher absorption peaks in the\nvisible range, substantial optical conductivities (~10$^{16}$ sec$^{-1}$), and\na lower percentage of reflection in the visible range make these compounds\nfascinating for solar cell applications. Whereas large values of Seebeck\ncoefficients, electrical conductivities, the figure of merits (greater than\nunity), and small values of thermal conductivities suggest the applications of\nthese compounds in thermoelectric generators.",
        "positive": "Graphene Physics in Graphite: Single layers of carbon dubbed \"graphenes\", from which graphite is built,\nhave attracted broad interest in the scientific community because of recent\nexciting experimental results. Graphene is interesting from a fundamental\nresearch perspective, as well as for potential technological applications.\nHere, we provide a brief overview of recent developments in this field,\nfocusing especially on the electronic properties of graphite. Experimental\nevidence indicates that high-quality graphite is a multi-layer system with\nnearly decoupled 2D graphene planes. Based on experimental observations, we\nanticipate that thin graphite samples and not single layers will be the most\npromising candidates for graphene-based electronics."
    },
    {
        "anchor": "Raman studies on a heavily distorted polycarbonate sample -\n  Raman-Untersuchungen an einer stark deformierten Polycarbonat-Probe: Differently distorted areas on a polycarbonate sample are studied by means of\nRaman spectroscopy. The various Raman lines, whose energy shifts range between\n200 and 3200 cm-1, are compared for different sample positions with respect to\ntheir spectral position, intensity and line width. While a double bonding does\nnot indicate a change in the structural characteristics of the distorted\npolycarbonate, CH-stretching modes show strong Raman intensity differences\ninduced by mechanical stress. Experimental setup modifications are outlooked.\n  Eine Polycarbonat-Probe wird an unterschiedlich stark deformierten Stellen\nmittels Raman-Spektroskopie untersucht. Die verschiedenen Raman-Linien mit\nRaman-Verschiebungen in einem Bereich von 200 bis 3200 cm-1 werden fuer die\nunterschiedlichen Probenstellen hinsichtlich ihrer spektralen Position,\nIntensitaet und Breite verglichen. Aus den experimentellen Resultaten geht\nhervor, dass Doppelbindungen nur unzureichend als Indikator fuer strukturelle\nVeraenderungen innerhalb des deformierten Polycarbonats dienen. Hingegen zeigen\nCH-Streckungen deutliche Raman-Intensitaetsunterschiede in Abhaengigkeit von\ndem Polycarbonat-Verspannungsgrad. Ein Ausblick auf experimentelle\nErweiterungen wird gegeben.",
        "positive": "Shear accelerated crystallization in a supercooled atomic liquid: A bulk metallic glass forming alloy is subjected to shear flow in its\nsupercooled state by compression of a short rod to produce a flat disc. The\nresulting material exhibits enhanced crystallization kinetics during isothermal\nannealing as reflected in the decrease of the crystallization time relative to\nthe non-deformed case. The transition from quiescent to shear-accelerated\ncrystallization is linked to strain accumulated during shear flow above a\ncritical shear rate $\\dot\\gamma_c\\approx 0.3$ s$^{-1}$ which corresponds to\nP\\'{e}clet number, $Pe\\sim\\mathcal{O}(1)$. The observation of shear accelerated\ncrystallization in an atomic system at modest shear rates is uncommon. It is\nmade possible here by the substantial viscosity of the supercooled liquid which\nincreases strongly with temperature in the approach to the glass transition. We\nmay therefore anticipate the encounter of non-trivial shear-related effects\nduring thermoplastic deformation of similar systems."
    },
    {
        "anchor": "Nonmonotonic strain dependence of lattice thermal conductivity in\n  monolayer SiC: a first-principles study: An increasing number of two-dimensional (2D) materials have already been\nachieved experimentally or predicted theoretically, which have potential\napplications in nano- and opto-electronics. Various applications for electronic\ndevices are closely related to their thermal transport properties. In this\nwork, the strain dependence of phonon transport in monolayer SiC with a perfect\nplanar hexagonal honeycomb structure is investigated by solving the linearized\nphonon Boltzmann equation. It is found that room-temperature lattice thermal\nconductivity ($\\kappa_L$) of monolayer SiC is two orders of magnitude lower\nthan that of graphene. The low $\\kappa_L$ is due to small group velocities and\nshort phonon lifetimes, which can also be explained by polarized covalent bond\ndue to large charge transfer from Si to C atoms. In considered strain range, it\nis proved that the SiC monolayer is mechanically and dynamically stable. With\nincreased tensile strain, the $\\kappa_L$ of SiC monolayer shows an unusual\nnonmonotonic up-and-down behavior, which is due to the competition between the\nchange of phonon group velocities and phonon lifetimes of low frequency phonon\nmodes. At low strains ($<$8\\%), the phonon lifetimes enhancement induces the\nincreased $\\kappa_L$, while at high strains ($>$8\\%) the reduction of group\nvelocities as well as the decrease of the phonon lifetimes are the major\nmechanism responsible for decreased $\\kappa_L$. Our works further enrich\nstudies on phonon transports of 2D materials with a perfect planar hexagonal\nhoneycomb structure, and motivate farther experimental studies.",
        "positive": "Tinselenidene: a Two-dimensional Auxetic Material with Ultralow Lattice\n  Thermal Conductivity and Ultrahigh Hole Mobility: By means of extensive ab initio calculations, a new two-dimensional (2D)\natomic material tin selenide monolayer (coined as tinselenidene) is predicted\nto be a semiconductor with an indirect gap (1.45 eV) and a high hole mobility\n(of order 10000 cm2V-1S-1), and will bear an indirect-direct gap transition\nunder a rather low strain (<0.5 GPa). Tinselenidene has a very small Young's\nmodulus (20-40 GPa) and an ultralow lattice thermal conductivity (<3 Wm-1K-1 at\n300 K), making it probably the most flexible and most heat-insulating material\nin known 2D atomic materials. In addition, tinseleniden has a large negative\nPoisson's ratio of -0.17, thus could act as a 2D auxetic material. With these\nintriguing properties, tinselenidene could have wide potential applications in\nthermoelectrics, nanomechanics and optoelectronics."
    },
    {
        "anchor": "Non-Local Phononic Crystals for Dispersion Customization and\n  Undulation-point Dynamics: Dispersion relations govern wave behaviors, and tailoring them is a grand\nchallenge in wave manipulation. We demonstrate inverse design of phononic\ndispersion using non-local interactions on one-dimensional spring-mass chains.\nFor both single-band and double-band cases, we can achieve any valid dispersion\ncurves with analytical precision. We further employ our method to design\nphononic crystals with multiple ordinary (roton/maxon) and higher-order\n(undulation) critical points and investigate their wave packet dynamics.",
        "positive": "The high-pressure behavior of CaMoO4: We report a high-pressure study of tetragonal scheelite-type CaMoO4 up to 29\nGPa. In order to characterize its high-pressure behavior, we have combined\nRaman and optical-absorption measurements with density-functional theory\ncalculations. We have found evidence of a pressure-induced phase transition\nnear 15 GPa. Experiments and calculations agree in assigning the high-pressure\nphase to a monoclinic fergusonite-type structure. The reported results are\nconsistent with previous powder x-ray-diffraction experiments, but are in\ncontradiction with the conclusions obtained from earlier Raman measurements,\nwhich support the existence of more than one phase transition in the pressure\nrange covered by our studies. The observed scheelite-fergusonite transition\ninduces significant changes in the electronic band gap and phonon spectrum of\nCaMoO4. We have determined the pressure evolution of the band gap for the low-\nand high-pressure phases as well as the frequencies and pressure dependences of\nthe Raman-active and infrared-active modes. In addition, based upon\ncalculations of the phonon dispersion of the scheelite phase, carried out at a\npressure higher than the transition pressure, we propose a possible mechanism\nfor the reported phase transition. Furthermore, from the calculations we\ndetermined the pressure dependence of the unit-cell parameters and atomic\npositions of the different phases and their room-temperature equations of\nstate. These results are compared with previous experiments showing a very good\nagreement. Finally, information on bond compressibility is reported and\ncorrelated with the macroscopic compressibility of CaMoO4. The reported results\nare of interest for the many technological applications of this oxide."
    },
    {
        "anchor": "Automated computation of materials properties: Materials informatics offers a promising pathway towards rational materials\ndesign, replacing the current trial-and-error approach and accelerating the\ndevelopment of new functional materials. Through the use of sophisticated data\nanalysis techniques, underlying property trends can be identified, facilitating\nthe formulation of new design rules. Such methods require large sets of\nconsistently generated, programmatically accessible materials data.\nComputational materials design frameworks using standardized parameter sets are\nthe ideal tools for producing such data. This work reviews the state-of-the-art\nin computational materials design, with a focus on these automated\n$\\textit{ab-initio}$ frameworks. Features such as structural prototyping and\nautomated error correction that enable rapid generation of large datasets are\ndiscussed, and the way in which integrated workflows can simplify the\ncalculation of complex properties, such as thermal conductivity and mechanical\nstability, is demonstrated. The organization of large datasets composed of\n$\\textit{ab-initio}$ calculations, and the tools that render them\nprogrammatically accessible for use in statistical learning applications, are\nalso described. Finally, recent advances in leveraging existing data to predict\nnovel functional materials, such as entropy stabilized ceramics, bulk metallic\nglasses, thermoelectrics, superalloys, and magnets, are surveyed.",
        "positive": "Magnetically-controlled impurities in quantum wires with strong Rashba\n  coupling: We investigate the effect of strong spin-orbit interaction on the electronic\ntransport through non-magnetic impurities in one-dimensional systems. When a\nperpendicular magnetic field is applied, the electron spin polarization becomes\nmomentum-dependent and spin-flip scattering appears, to first order in the\napplied field, in addition to the usual potential scattering. We analyze a\nsituation in which, by tuning the Fermi level and the Rashba coupling, the\nmagnetic field can suppress the potential scattering. This mechanism should\ngive rise to a significant negative magnetoresistance in the limit of large\nbarriers."
    },
    {
        "anchor": "Two-dimensional spin systems in PECVD-grown diamond with tunable density\n  and long coherence for enhanced quantum sensing and simulation: Systems of spins engineered with tunable density and reduced dimensionality\nenable a number of advancements in quantum sensing and simulation. Defects in\ndiamond, such as nitrogen-vacancy (NV) centers and substitutional nitrogen (P1\ncenters), are particularly promising solid-state platforms to explore. However,\nthe ability to controllably create coherent, two-dimensional spin systems and\ncharacterize their properties, such as density, depth confinement, and\ncoherence is an outstanding materials challenge. We present a refined approach\nto engineer dense ($\\gtrsim$1 ppm$\\cdot$nm), 2D nitrogen and NV layers in\ndiamond using delta-doping during plasma-enhanced chemical vapor deposition\n(PECVD) epitaxial growth. We employ both traditional materials techniques, e.g.\nsecondary ion mass spectrometry (SIMS), alongside NV spin decoherence-based\nmeasurements to characterize the density and dimensionality of the P1 and NV\nlayers. We find P1 densities of 5-10 ppm$\\cdot$nm, NV densities between 1 and\n3.5 ppm$\\cdot$nm tuned via electron irradiation dosage, and depth confinement\nof the spin layer down to 1.6 nm. We also observe high (up to 0.74) ratios of\nP1 to NV centers and reproducibly long NV coherence times, dominated by dipolar\ninteractions with the engineered P1 and NV spin baths.",
        "positive": "Equation of state of single-crystal cubic boron phosphide: The 300 K equation of state of cubic (zinc-blende) boron phosphide BP has\nbeen studied by in situ single-crystal X-ray diffraction with synchrotron\nradiation up to 55 GPa. The measurements have been performed under\nquasi-hydrostatic conditions using a Ne pressure medium in a diamond anvil\ncell. A fit of the experimental p-V data to the Vinet equation of state yields\nthe bulk modulus B0 of 179(1) GPa with its pressure derivative of 3.3(1). These\nvalues are in a good agreement with previous elastic measurements, as well as\nwith semiempirical estimations."
    },
    {
        "anchor": "Revisiting thermodynamics in (LiF, NaF, KF, CrF2)-CrF3 by\n  first-principles calculations and CALPHAD modeling: The thermodynamic description of the (LiF, NaF, KF, CrF2)-CrF3 systems has\nbeen revisited, aiming for a better understanding of the effects of Cr on the\nFLiNaK molten salt. First-principles calculations based on density functional\ntheory (DFT) were performed to determine the electronic and structural\nproperties of each compound, including the formation enthalpy, volume, and bulk\nmodulus. DFT-based phonon calculations were carried out to determine the\nthermodynamic properties of compounds, for example, enthalpy, entropy, and heat\ncapacity as functions of temperature. Phonon-based thermodynamic properties\nshow a good agreement with experimental data of binary compounds LiF, NaF, KF,\nCrF3, and CrF2, establishing a solid foundation to determine thermodynamic\nproperties of ternary compounds as well as to verify results estimated by the\nNeumann-Kopp rule. Additionally, DFT-based ab initio molecular dynamics (AIMD)\nsimulations were employed to predict the mixing enthalpies of liquid salts.\nUsing DFT-based results and experimental data in the literature, the (LiF, NaF,\nKF, CrF2)-CrF3 system has been remodeled in terms of the CALculation of PHAse\nDiagrams (CALPHAD) approach using the modified quasichemical model with\nquadruplet approximation (MQMQA) for liquid. Calculated phase stability in the\npresent work shows an excellent agreement with experiments, indicating the\neffectiveness of combining DFT-based total energy, phonon, and AIMD\ncalculations, and CALPHAD modeling to provide the thermodynamic description in\ncomplex molten salt systems.",
        "positive": "Spin-dependent interactions in orbital-density-dependent functionals:\n  non-collinear Koopmans spectral functionals: The presence of spin-orbit coupling or non-collinear magnetic spin states can\nhave dramatic effects on the ground-state and spectral properties of materials,\nin particular on the band structure. Here, we develop non-collinear\nKoopmans-compliant functionals based on Wannier functions and\ndensity-functional perturbation theory, targeting accurate spectral properties\nin the quasiparticle approximation. Our non-collinear Koopmans-compliant theory\ninvolves functionals of four-component orbitals densities, that can be obtained\nfrom the charge and spin-vector densities of Wannier functions. We validate our\napproach on three emblematic and diverse semiconductors where the effect of\nspin-orbit coupling goes from small to very large: the III-IV semiconductor\nGaAs, the transition-metal dichalcogenide WSe$_2$, and the cubic perovskite\nCsPbBr$_3$. The predicted band gaps are comparable in accuracy to\nstate-of-the-art many-body perturbation theory and include spin-dependent\ninteractions and screening effects that are missing in standard diagrammatic\napproaches based on the random phase approximation. While the inclusion of\norbital- and spin-dependent interactions in many-body perturbation theory\nrequires self-screening or vertex corrections, that emerges naturally in the\nKoopmans-functionals framework."
    },
    {
        "anchor": "Critical Analysis of an FeP Empirical Potential Employed to Study\n  Fracture of Metallic Glasses: An empirical potential that has been widely used to perform molecular\ndynamics studies on the fracture behavior of FeP metallic glasses is shown to\nexhibit spinodal decomposition in the composition range commonly studied. The\nphosphorous segregation induces a transition from ductility to brittleness.\nDuring brittle fracture the atomically sharp crack tip propagates along a\npercolating path with higher P concentration. This embrittlement is observed to\noccur over a wide range of chemical compositions, and toughness decreases\nlinearly with the degree of compositional segregation over the entire the\nregime studied. Stable glass forming alloys that can be quenched at low quench\nrates do not, as a rule, exhibit such thermodynamically unstable behavior near\nto or above their glass transition temperatures. Hence, the microstructures\nexhibited in these simulations are unlikely to reflect the actual\nmicrostructures or fracture behaviors of the glassy alloys they seek to\nelucidate.",
        "positive": "Anomalous entropy-driven kinetics of dislocation nucleation: The kinetics of dislocation reactions, such as dislocation multiplication,\ncontrols the plastic deformation in crystals beyond their elastic limit,\ntherefore critical mechanisms in a number of applications in materials science.\nWe present a series of large-scale molecular dynamics simulations that shows\nthat one such type of reactions, the nucleation of dislocation at free\nsurfaces, exhibit extremely unconventional kinetics, including unexpectedly\nlarge nucleation rates under compression, very strong entropic stabilization\nunder tension, as well as strong non-Arrhenius behavior. These unusual kinetics\nare quantitatively rationalized using a variational transition state theory\napproach coupled with an efficient numerical scheme for the estimation of\nvibrational entropy changes. These results highlight the need for a variational\ntreatment of the kinetics to quantitatively capture dislocation reaction\nkinetics, especially at low-to-moderate strains where large deformations are\nrequired to activate reactions. These observations suggest possible\nexplanations to previously observed unconventional deformation kinetics in both\nmolecular dynamics simulations and experiments."
    },
    {
        "anchor": "The different roles of Pu-oxide overlayers in the hydrogenation of\n  Pu-metal: An ab initio molecular dynamics study based on vdW-DFT+U: Based on the van der Waals density functional theory (vdW-DFT)+U scheme, we\ncarry out the ab initio molecular dynamics (AIMD) study of the interaction\ndynamics for H$_{2}$ impingement against the stoichiometric PuO$_{2}$(111), the\nreduced PuO$_{2}$(111), and the stoichiometric $\\alpha $-Pu$_{2}$O$_{3}$(111)\nsurfaces. The hydrogen molecular physisorption states, which can not be\ncaptured by pure DFT+\\textit{U} method, are obtained by employing the\nvdW-DFT+\\textit{U} scheme. We show that except for the weak physisorption,\nPuO$_{2}$(111) surfaces are so difficult of access that almost all of the\nH$_{2}$ molecules will bounce back to the vacuum when their initial kinetic\nenergies are not sufficient. Although the dissociative adsorption of H$_{2}$ on\nPuO$_{2}$(111) surfaces is found to be very exothermic, the collision-induced\ndissociation barriers of H$_{2}$ are calculated to be as high as $3.2$ eV and\n$2.0$ eV for stoichiometric and reduced PuO$_{2}$ surfaces, respectively.\nUnlike PuO$_{2}$, our AIMD study directly reveals that the hydrogen molecules\ncan penetrate into $\\alpha $-Pu$_{2}$O$_{3}$(111) surface and diffuse easily\ndue to the $25$\\ native O vacancies located along the $\\langle $111$\\rangle $\ndiagonals of $\\alpha $-Pu$_{2}$O$_{3}$ matrix. By examining the temperature\neffect and the internal vibrational excitations of H$_{2}$, we provide a\ndetailed insight into the interaction dynamics of H$_{2}$ in $\\alpha\n$-Pu$_{2}$O$_{3}$. The optimum pathways for hydrogen penetration and diffusion,\nthe corresponding energy barriers ($1.0$ eV and $0.53$ eV, respectively) and\nrate constants are systematically calculated. Overall, our study fairly reveals\nthe different interaction mechanisms between H$_{2}$ and Pu-oxide surfaces,\nwhich have strong implications to the interpretation of experimental\nobservations.",
        "positive": "In-situ x-ray diffraction and the evolution of polarization during the\n  growth of ferroelectric superlattices: In epitaxially strained ferroelectric thin films and superlattices, the\nferroelectric transition temperature can lie above the growth temperature.\nFerroelectric polarization and domains should then evolve during the growth of\na sample, and electrostatic boundary conditions may play an important role. In\nthis work, ferroelectric domains, surface termination, average lattice\nparameter and bilayer thickness are simultaneously monitored using in-situ\nsynchrotron x-ray diffraction during the growth of BaTiO$_3$/SrTiO$_3$\nsuperlattices on SrTiO$_3$ substrates by off-axis RF magnetron sputtering. The\ntechnique used allows for scan times substantially faster than the growth of a\nsingle layer of material. Effects of electric boundary conditions are\ninvestigated by growing the same superlattice alternatively on SrTiO$_3$\nsubstrates and 20nm SrRuO$_3$ thin films on SrTiO$_3$ substrates. These\nexperiments provide important insights into the formation and evolution of\nferroelectric domains when the sample is ferroelectric during the growth\nprocess."
    },
    {
        "anchor": "Visualising emergent phenomena at oxide interfaces: Knowledge of atomic-level details of structure, chemistry, and electronic\nstates is paramount for a comprehensive understanding of emergent properties at\noxide interfaces. We utilise a novel methodology based on atomic-scale electron\nenergy loss spectroscopy (EELS) to spatially map the electronic states tied to\nthe formation of a two-dimensional electron gas (2DEG) at the prototypical\nnon-polar/polar $TiO_2$/$LaAlO_3$ interface. Combined with differential phase\ncontrast analysis we directly visualise the microscopic locations of ions and\ncharge and find that 2DEG states and $Ti^{3+}$ defect states exhibit different\nspatial distributions. Supported by density functional theory (DFT) and\ninelastic scattering simulations we examine the role of oxygen vacancies in\n2DEG formation. Our work presents a general pathway to directly image emergent\nphenomena at interfaces using this unique combination of arising microscopy\ntechniques with machine learning assisted data analysis procedures.",
        "positive": "Half-Heusler topological insulators: Ternary semiconducting or metallic half-Heusler compounds with an atomic\ncomposition 1:1:1 are widely studied for their flexible electronic properties\nand functionalities. Recently, a new material property of half-Heusler\ncompounds was predicted based on electronic structure calculations: the\ntopological insulator. In topological insulators, the metallic surface states\nare protected from impurity backscattering due to spin-momentum locking. This\nopens up new perspectives in engineering multifunctional materials. In this\narticle, we introduce half Heusler materials from the crystallographic and\nelectronic structure point of view. We present an effective model Hamiltonian\nfrom which the topological state can be derived, notably from a non-trivial\ninverted band structure. We discuss general implications of the inverted band\nstructure with a focus on the detection of the topological surface states in\nexperiments by reviewing several exemplary materials. Special attention is\ngiven to superconducting half-Heusler materials, which have attracted ample\nattention as a platform for non-centrosymmetric and topological\nsuperconductivity."
    },
    {
        "anchor": "An Environment-dependent Semi-Empirical Tight Binding Model Suitable for\n  Electron Transport in Bulk Metals, Metal Alloys, Metallic Interfaces and\n  Metallic Nanostructures II - Effect of Confinement and Homogeneous Strain on\n  Cu Conductance: The Semi-Empirical TB model developed in part I is applied to metal transport\nproblems of current relevance in part II. A systematic study of the effect of\nquantum confinement, transport orientation and homogeneous strain on electronic\ntransport properties of Cu is carried out. It is found that quantum confinement\nfrom bulk to nanowire boundary conditions leads to significant anisotropy in\nconductance of Cu along different transport orientations. Compressive\nhomogeneous strain is found to reduce resistivity by increasing the density of\nconducting modes in Cu. The [110] transport orientation in Cu nanowires is\nfound to be the most favorable for mitigating conductivity degradation since it\nshows least reduction in conductance with confinement and responds most\nfavorably to compressive strain.",
        "positive": "Two-dimensional multiferroic metal with voltage-tunable magnetization\n  and metallicity: We design a multiferroic metal that combines seemingly incompatible\nferromagnetism, ferroelectricity, and metallicity by hole doping a\ntwo-dimensional (2D) ferroelectric with high density of states near the Fermi\nlevel. The strong magnetoelectric effect is demonstrated in hole-doped and\narsenic-doped monolayer {\\alpha}-In2Se3 using first-principles calculations.\nTaking advantage of the oppositely charged surfaces created by an out-of-plane\npolarization, the 2D magnetization and metallicity can be electrically switched\non and off in an asymmetrically doped monolayer. The substitutional arsenic\ndefect pair exhibits an intriguing electric field-tunable charge\ndisproportionation process accompanied with an on-off switch of local magnetic\nmoments. The charge ordering process can be controlled by tuning the relative\nstrength of on-site Coulomb repulsion and defect dipole-polarization coupling\nvia strain engineering. Our design principle relying on no transition metal\nbroadens the materials design space for 2D multiferroic metals."
    },
    {
        "anchor": "Observation of Ultrafast Free Carrier Dynamics in Single Layer MoS$_2$: The dynamics of excited electrons and holes in single layer (SL) MoS$_2$ have\nso far been difficult to disentangle from the excitons that dominate the\noptical response of this material. Here, we use time- and angle-resolved\nphotoemission spectroscopy for a SL of MoS$_2$ on a metallic substrate to\ndirectly measure the excited free carriers. This allows us to ascertain a\ndirect quasiparticle band gap of 1.95 eV and determine an ultrafast (50 fs)\nextraction of excited free carriers via the metal in contact with the SL\nMoS$_2$. This process is of key importance for optoelectronic applications that\nrely on separated free carriers rather than excitons.",
        "positive": "Crystallite Size Effect on Lattice Strain and Crystal Structure of\n  Ba1/4Sr3/4MnO3 Layered Perovskite Manganite: The single phase polycrystalline Ba1/4Sr3/4MnO3 layered perovskite manganite\nhas been synthesized by combustion method having various crystallite sizes. The\nroom temperature X-ray diffraction patterns reveal that Ba1/4Sr3/4MnO3\ncrystallizes into hexagonal crystal structure with space group P63/mmc as\nconfirmed by Rietveld refinement. The scanning electron micrographs of\nBa1/4Sr3/4MnO3 reveal uniform crystallite size of the samples. Effect of\ncrystallite size on lattice strain and crystal structure has been studied using\nRietveld refinement and Williamson-Hall plot, respectively. The structural\nlattice parameters decrease with increasing crystallite size. However, lattice\nstrain increases with increasing crystallite-size."
    },
    {
        "anchor": "Weakly Nonlinear Theory of Dynamic Fracture: The common approach to crack dynamics, linear elastic fracture mechanics\n(LEFM), assumes infinitesimal strains and predicts a $r^{-1/2}$ strain\ndivergence at a crack tip. We extend this framework by deriving a weakly\nnonlinear fracture mechanics theory incorporating the leading nonlinear elastic\ncorrections that must occur at high strains. This yields strain contributions\n\"more-divergent\" than $r^{-1/2}$ at a finite distance from the tip and\nlogarithmic corrections to the parabolic crack tip opening displacement. In\naddition, a dynamic length-scale, associated with the nonlinear elastic zone,\nemerges naturally. The theory provides excellent agreement with recent near-tip\nmeasurements that can not be described in the LEFM framework.",
        "positive": "Creation of flexible spin-caloritronic material with giant transverse\n  thermoelectric conversion by nanostructure engineering: Functional materials such as magnetic, thermoelectric, and battery materials\nhave been revolutionized through nanostructure engineering. However, spin\ncaloritronics, an advancing field based on spintronics and thermoelectrics with\nfundamental physics studies, has focused only on uniform materials without\ncomplex microstructures. Here, we show how nanostructure engineering enables\ntransforming simple magnetic alloys into spin-caloritronic materials displaying\nsignificantly large transverse thermoelectric conversion properties. The\nanomalous Nernst effect (ANE), a promising transverse thermoelectric phenomenon\nfor energy harvesting and heat sensing, has been challenging to utilize due to\nthe scarcity of materials with large anomalous Nernst coefficients. We\ndemonstrate a remarkable improvement in the anomalous Nernst coefficients in\nflexible Fe-based amorphous materials through nanostructural engineering,\nwithout altering their composition. This surpasses all reported amorphous\nalloys and is comparable to single crystals showing large ANE. The enhancement\nis attributed to Cu nano-clustering, facilitating efficient transverse\nthermoelectric conversion. This discovery advances the materials science of\nspin caloritronics, opening new avenues for designing high-performance\ntransverse thermoelectric devices for practical applications."
    },
    {
        "anchor": "Inverse magnetocaloric effect in polycrystalline\n  La$_{0.125}$Ca$_{0.875}$MnO$_{3}$: Recently the inverse magnetocaloric effect is observed for different\ncompounds. However there is very rare for any manifestation of the effect to be\nseen in manganites. We have found inverse magnetocaloric effect in the case of\npolycrystalline La$_{0.125}$Ca$_{0.875}$MnO$_{3}$. Such phenomenon is\nattributed to the stabilization of antiferromagnetic state associated with\ninherent magnetic inhomogeneous phases for this compound.",
        "positive": "On the impact of capillarity for strength at the nanoscale: The interior of nanoscale crystals experiences stress that compensates the\ncapillary forces and that can be large, in the order of 1 GPa. Various studies\nhave speculated on whether and how this surface-induced stress affects the\nstability and plasticity of small crystals. Yet, experiments have so far failed\nto discriminate between the surface contribution and other, bulk-related size\neffects. In order to clarify the issue, we study the variation of the flow\nstress of a nanomaterial while distinctly different variations of the two\ncapillary parameters surface tension and surface stress are imposed under\ncontrol of an applied electric potential. Our theory qualifies the suggested\nimpact of $\\textit{surface stress}$ as not forceful and instead predicts a\nsignificant contribution of the surface energy, as measured by the\n$\\textit{surface tension}$. The predictions for the combined potential- and\nsize dependence of the flow stress are quantitatively supported by the\nexperiment. Previous suggestions, favoring the surface stress as the relevant\ncapillary parameter, are not consistent with the experiment."
    },
    {
        "anchor": "Adsorption-induced symmetry reduction of metal-phthalocyanines studied\n  by vibrational spectroscopy: We investigate the vibrational properties of Pt- and Pd-phthalocyanine (PtPc\nand PdPc) molecules on Ag(111) with high resolution electron energy loss\nspectroscopy (HREELS). In the monolayer regime, both molecules exhibit long\nrange order. The vibrational spectra prove a flat adsorption geometry. The red\nshift of vibrational modes and the presence of asymmetric vibrational peaks\nsuggest a moderate interaction of the molecules with the substrate, accompanied\nby a static charge transfer from the metal to the molecules. The appearance of\na particular vibrational mode, which (i) belongs to the $\\mathrm{B_{1g}}$\nrepresentation of the original fourfold $\\mathrm{D_{4h}}$ molecular symmetry\ngroup and which (ii) exhibits interfacial dynamical charge transfer (IDCT),\nproves that a preferential charge transfer from the Ag surface into one of the\noriginally doubly degenerate lowest unoccupied molecular orbitals (LUMOs) of\n$\\mathrm{E_g}$ symmetry takes place, i.e. the electronic degeneracy is lifted\nand the molecule-surface complex acquires the twofold symmetry group\n$\\mathrm{C_{2v}}$. The vibration-based analysis of orbital degeneracies, as\ncarried out here for PtPc/Ag(111) and PdPc/Ag(111), is not restricted to these\ncases. It is particularly useful whenever the presence of multiple molecular\nin-plane orientations at the interface makes the analysis of orbital\ndegeneracies with angle-resolved photoemission spectroscopy difficult.",
        "positive": "Quantum transport properties of ultrathin silver nanowires: The quantum transport properties of the ultrathin silver nanowires are\ninvestigated. For a perfect crystalline nanowire with four atoms per unit cell,\nthree conduction channels are found, corresponding to three $s$ bands crossing\nthe Fermi level. One conductance channel is disrupted by a single-atom defect,\neither adding or removing one atom. Quantum interference effect leads to\noscillation of conductance versus the inter-defect distance. In the presence of\nmultiple-atom defect, one conduction channel remains robust at Fermi level\nregardless the details of defect configuration. The histogram of conductance\ncalculated for a finite nanowire (seven atoms per cross section) with a large\nnumber of random defect configurations agrees well with recent experiment."
    },
    {
        "anchor": "First principles study of the multiferroics BiFeO$_{3}$,\n  Bi$_{2}$FeCrO$_{6}$, and BiCrO$_{3}$: Structure, polarization, and magnetic\n  ordering temperature: We present results of an {\\it ab initio} density functional theory study of\nthree bismuth-based multiferroics, BiFeO$_{3}$, Bi$_{2}$FeCrO$_{6}$, and\nBiCrO$_{3}$. We disuss differences in the crystal and electronic structure of\nthe three systems, and we show that the application of the LDA+$U$ method is\nessential to obtain realistic structural parameters for Bi$_{2}$FeCrO$_{6}$. We\ncalculate the magnetic nearest neighbor coupling constants for all three\nsystems and show how Anderson's theory of superexchange can be applied to\nexplain the signs and relative magnitudes of these coupling constants. From the\ncoupling constants we then obtain a mean-field approximation for the magnetic\nordering temperatures. Guided by our comparison of these three systems, we\ndiscuss the possibilities for designing a multiferroic material with large\nmagnetization above room temperature.",
        "positive": "Trends of higher-order exchange interactions in transition-metal\n  trilayers: We present a systematic study of higher-order exchange interactions beyond\nthe pair-wise Heisenberg exchange in transition-metal trilayers based on\ndensity functional theory calculations. We show that these terms can play an\nimportant role in magnetic trilayers composed of a single hexagonal Fe or Co\natomic layer sandwiched between $4d$ and $5d$ transition-metal layers. We study\nthe dependence of the biquadratic and the three-site and four-site four spin\ninteraction on the band filling of the $4d$ and $5d$ layers as well as the\nstacking sequence, i.e. fcc vs. hcp stacking. Our calculations reveal\nrelatively small higher-order interactions for Co based trilayers. For Fe based\ntrilayers with a Rh or Ir layer the higher-order terms can be on the same order\nof magnitude as pair-wise Heisenberg exchange. The trends obtained for\nfreestanding trilayers are used to understand the higher-order interactions in\nultrathin film systems on surfaces that are experimentally accessible. It is\nshown that hcp Rh/Fe/Ir(111) and hcp-Rh/Fe/Rh(111) exhibit the largest values\nfor the biquadratic and the three-site four spin interaction of all systems\nunder study. We further demonstrate that the three-site four spin interaction\nis responsible for the experimentally observed change of the magnetic ground\nstate of Rh/Fe/Ir(111) from a spin spiral (single-Q) for fcc-Rh to a 2Q state\nfor hcp-Rh. We find similar trends for Rh/Fe/Rh(111), i.e. replacing the Ir\nsurface by the isoelectronic Rh surface. For Rh/Co/Ir(111), we obtain a\nnegative value for the four-site four spin interaction which will lead to a\nreduced stability of magnetic skyrmions which are metastable in this film at\nzero magnetic field. In contrast, for Pd/Fe/Ir(111), the four-site four spin\ninteraction is positive which leads to an enhanced stability of skyrmions."
    },
    {
        "anchor": "Simulations of NO dissociative adsorption on an atomically thin Cu layer: To investigate chemical reactivity of Cu atomic-scale structures, we\nperformed simulations based on the generalized gradient approximation in the\ndensity functional theory. An atomic layer of Cu forming a triangular lattice\n(TL) was found to give a stable structure. The nitrogen monoxide molecule (NO)\nwas adsorbed on some atomic sites of TL or on an atomic step structure (ASS) of\nCu. The molecular adsorption energy on TL was -0.83 eV. Our data suggested that\ndissociative adsorption of NO with a dissociation energy of -1.08 eV was\npossible with an energy barrier of order 1.4 eV. In this optimized structure,\nthe nitrogen and oxygen atoms were embedded in the Cu layer. On the step, NO\nadsorbed at a bridge site and the formation energy of Cu-(NO)-Cu local bond\nconnections was estimated to be around -1.32 eV. Molecular dissociation of NO\nwith a dissociation energy of -0.37 eV was also possible around ASS.",
        "positive": "Scaling behaviors of RESET voltages and currents in unipolar resistance\n  switching: Unipolar switching phenomena have attracted a great deal of recent attention,\nbut the wide distributions of switching voltages still pose major obstacles for\nscientific advancement and practical applications. Using NiO capacitors, we\ninvestigated the distributions of the RESET voltage and current. We found that\nthey scaled with the resistance value Ro in the low resistance state, and that\nthe scaling exponents varied at Ro = 30 Ohm. We explain these intriguing\nscaling behaviors and their crossovers by analogy with percolation theory. We\nshow that the connectivity of conducting filaments plays a crucial role in the\nRESET process."
    },
    {
        "anchor": "The Premartensite and Martensite in Fe50Rh50 System: Metallic/intermetalic materials with BCC structures hold an intrinsic\ninstability due to phonon softening along [110] dirrection, causing BCC to\nlower-symmetry phases transformation when the BCC structures are thermally or\nmechanically stressed. Fe50Rh50 binary system is one of the exceptional BCC\nstructures (ordered-B2) that has not been yet showing such transformation upon\napplication of thermal stress, although mechanical deformation results in B2 to\ndisordered FCC (gamma) and L10 phases transformation. Here, a comprehensive\ntransmission electron microscopy (TEM) study is conducted on thermally-stressed\nsamples of Fe50Rh50 aged at water and liquid nitrogen from 1150 degree C and\n1250 degree C. The results show that, samples quenched from 1150 degree C into\nwater and liquid nitrogen show presence of 1/4{110} and 1/2{110} satellite\nreflections, the latter of which is expected from phonon dispersion curves\nobtained by density functional theory calculation. Therefore, it is believed\nthat Fe50Rh50 maintains the B2 structure that is in premartensite state. Once\nFe50Rh50 is quenched from 1250 degree C into liquid nitrogen, formation of two\nshort-range ordered tetragonal phases with various c/a ratios (~1.15 and 1.4)\nis observed in line with phases formed from mechanically deformed (30%) sample.\nAccording to our observations, an accurate atomistic shear model ({110}<1-10>)\nis presented that describes the martensitic transformation of B2 to these\ntetragonal phases. These findings offer implications useful for understanding\nof magnetic and physical characteristics of metallic/intermetallic materials.",
        "positive": "Free energy of (CoxMn1-x)3O4 mixed phases from machine-learning-enhanced\n  ab initio calculations: (CoxMn1-x)3O4 is a promising candidate material for solar thermochemical\nenergy storage. A high-temperature model for this system would provide a\nvaluable tool for evaluating its potential. However, predicting phase diagrams\nof complex systems with ab initio calculations is challenging due to the varied\nsources affecting the free energy, and with the prohibitive amount of\nconfigurations needed in the configurational entropy calculation. In this work,\nwe compare three different machine learning (ML) approaches for sampling the\nconfiguration space of (CoxMn1-x)3O4, including a simpler ML approach, which\nwould be suitable for application in high-throughput studies. We use\nexperimental data for a feature of the phase diagram to assess the accuracy of\nmodel predictions. We find that with some methods, data pre-treatment is needed\nto obtain accurate predictions due to inherently composition-imbalanced\ntraining data for a mixed phase. We highlight that the important entropy\ncontributions depend on the physical regimes of the system under investigation\nand that energy predictions with ML models are more challenging at compositions\nwhere there are energetically competing ground state crystal structures.\nSimilar methods to those outlined here can be used to screen other candidate\nmaterials for thermochemical energy storage"
    },
    {
        "anchor": "Plasmon tunability in metallodielectric metamaterials: The dielectric properties of metamaterials consisting of periodically\narranged metallic nanoparticles of spherical shape are calculated by rigorously\nsolving Maxwell's equations. Effective dielectric functions are obtained by\ncomparing the reflectivity of planar surfaces limiting these materials with\nFresnel's formulas for equivalent homogeneous media, showing mixing and\nsplitting of individual-particle modes due to inter-particle interaction.\nDetailed results for simple cubic and fcc crystals of aluminum spheres in\nvacuum, silver spheres in vacuum, and silver spheres in a silicon matrix are\npresented. The filling fraction of the metal f is shown to determine the\nposition of the plasmon modes of these metamaterials. Significant deviations\nare observed with respect to Maxwell-Garnett effective medium theory for large\nf, and multiple plasmons are predicted to exist in contrast to Maxwell-Garnett\ntheory.",
        "positive": "Three-dimensional operando optical imaging of single particle and\n  electrolyte heterogeneities inside Li-ion batteries: Understanding (de)lithiation heterogeneities in battery materials is key to\nensuring optimal electrochemical performance and developing better energy\nstorage devices. However, this remains challenging due to the complex three\ndimensional morphology of microscopic electrode particles, the involvement of\nboth solid and liquid phase reactants, and range of relevant timescales\n(seconds to hours). Here, we overcome this problem and demonstrate the use of\nbench-top laser scanning confocal microscopy for simultaneous three-dimensional\noperando measurement of lithium ion dynamics in single particles, and the\nelectrolyte, in batteries. We examine two technologically important cathode\nmaterials that are known to suffer from intercalation heterogeneities: LixCoO2\nand LixNi0.8Mn0.1Co0.1O2. The single-particle surface-to-core transport\nvelocity of Li-phase fronts, and volume changes - as well as their\ninter-particle heterogeneity - are captured as a function of C-rate, and\nbenchmarked to previous ensemble measurements. Additionally, we visualise\nheterogeneities in the bulk and at the surface of particles during cycling, and\nimage the formation of spatially non-uniform concentration gradients within the\nliquid electrolyte. Importantly, the conditions under which optical imaging can\nbe performed inside absorbing and multiply scattering materials such as battery\nintercalation compounds are outlined."
    },
    {
        "anchor": "Short range ordering of heavy element columns in nickel based\n  superalloys: To obtain comprehensive performance, heavy elements were added into\nsuperalloys for solid solution hardening. In this article, it is found by\nscanning transmission electron microscope observation that rather than\ndistribute randomly heavy-atom columns prefer to align along <100> and <110>\ndirection and form a short-range ordering with the heavy-element stripes 1-2 nm\nin length. Due to the strong bonding strength between the refractory elements\nand Ni atoms, this short-range ordering will be beneficial to the mechanical\nperformances.",
        "positive": "High pressure-high temperature phase diagram of ammonia: The high pressure(P)-high temperature(T) phase diagram of solid ammonia has\nbeen investigated using diamond anvil cell and resistive heating techniques.\nThe III-IV transition line has been determined up to 20 GPa and 500 K both on\ncompression and decompression paths. No discontinuity is observed at the\nexpected location for the III-IV-V triple point. The melting line has been\ndetermined by visual observations of the fluid-solid equilibrium up to 9 GPa\nand 900 K. The experimental data is well fitted by a Simon-Glatzel equation in\nthe covered P-T range. These transition lines and their extrapolations are\ncompared with reported calculations."
    },
    {
        "anchor": "Size confinement effect in graphene grown on 6H-SiC (0001) substrate: We have observed the energy structure in the density of occupied states of\ngraphene grown on n-type 6H-SiC (0001). The structure revealed with\nphotoelectron spectroscopy is described by creation of the quantum well states\nwhose number and the energy position (E1 = 0.3 eV, E2 = 1.2 eV, E3 = 2.6 eV )\ncoincide with the calculated ones for deep (V = 2.9 eV) and narrow (d = 2.15 A)\nquantum well formed by potential relief of the valence bands in the structure\ngraphene/n-SiC. We believe that the quantum well states should be formed also\nin graphene on dielectric and in suspended graphene.",
        "positive": "Tuning magnetostructural phase transition in CoMn$_{0.88}$Cu$_{0.12}$Ge\n  by application of hydrostatic pressure: Structural and magnetic properties of the CoMn$_{0.88}$Cu$_{0.12}$Ge compound\nhave been investigated using X-ray diffraction (XRD) and differential scanning\ncalorimetry (DSC) accompanied with investigation of magnetic properties under\napplied hydrostatic pressure up to 12 kbar. It has been found that the\northorhombic crystal structure of the TiNiSi-type, which is dominant at low\ntemperatures, turns into the hexagonal Ni$_2$In-type one, slightly above 200 K.\nThe structural transition is of the first-order type as confirmed by presence\nof distinct thermal hysteresis exceeding 20 K. The ac magnetic measurements\nindicate a ferromagnetic order below the Curie temperature $T_C$ of 238 K,\nfollowed by additional anomaly at lower temperatures - the latter one being\nrelated to the structural transition. Application of hydrostatic pressure leads\nto temperature separation of the purely magnetic transition, whose Curie\ntemperature $T_C$ slowly increases with applied pressure, and the\nmagnetostructural transition characterized by critical temperature showing much\nrapid decrease with increasing pressure. Comparison of the DSC data for the\ninvestigated compound and the isostructural CoMn$_{0.95}$Cu$_{0.05}$Ge one has\nmade it possible to determine both the structural and magnetic components of\nentropy change."
    },
    {
        "anchor": "Depth resolved study of annealing in IrMn/(Fe, Co, CoFe) exchange bias\n  systems: Depth resolved study of structural and magnetic profiles of\nantiferromagnetic/ferromagnetic (AFM/FM) system upon annealing was performed in\nthis work. We studied systems comprising of AFM IrMn and FM (Co, Fe,\nCo$_{70}$Fe$_{30}$) structures using polarized neutron and soft X-ray\nscattering, secondary neutral spectrometry, and magnetometry. Structural depth\nprofiles obtained from neutron reflectometry indicate non-homogeneity of the\nAFM layer even before annealing, which is associated with the migration of\nmanganese to the surface of the sample along grain boundaries. Annealing of\nsamples with CoFe and Co layers leads to a slight increase in the migration of\nmanganese, which, however, does not lead to significant degradation of the\nexchange coupling at the AFM/FM interface. A significantly different picture\nwas observed in the Fe/IrMn systems where a strong migration of iron into the\nAFM layer was observed upon annealing of the sample, leading to erosion of the\nmagnetic profile, the formation of a non-magnetic alloy and degradation of the\npinning strength. This study can be useful in the design of AF/FM systems in\ndifferent spintronics devices, including HDD read heads, where thermal\nannealing is applied at different stages of the device manufacturing process.",
        "positive": "Morphological stability of solid-liquid interfaces under additive\n  manufacturing conditions: Understanding rapid solidification behavior at velocities relevant to\nadditive manufacturing (AM) is critical to controlling microstructure\nselection. Although in-situ visualization of solidification dynamics is now\npossible, systematic studies under AM conditions with microstructural outcomes\ncompared to solidification theory remain lacking. Here we measure solid-liquid\ninterface velocities of Ni-Mo-Al alloy single crystals under AM conditions with\nsynchrotron X-ray imaging, characterize the microstructures, and show\ndiscrepancies with classical theories regarding the onset velocity for absolute\nstability of a planar solid-liquid interface. Experimental observations reveal\ncellular/dendritic microstructures can persist at velocities larger than the\nexpected absolute stability limit, where banded structure formation should\ntheoretically appear. We show that theory and experimental observations can be\nreconciled by properly accounting for the effect of solute trapping and kinetic\nundercooling on the velocity-dependent solidus and liquidus temperatures of the\nalloy. Further theoretical developments and accurate assessments of key\nthermophysical parameters - like liquid diffusivities, solid-liquid interface\nexcess free energies, and kinetic coefficients - remain needed to\nquantitatively investigate such discrepancies and pave the way for the\nprediction and control of microstructure selection under rapid solidification\nconditions."
    },
    {
        "anchor": "Diffusion-controlled phase growth on dislocations: We treat the problem of diffusion of solute atoms around screw dislocations.\nIn particular, we express and solve the diffusion equation, in radial symmetry,\nin an elastic field of a screw dislocation subject to the flux conservation\nboundary condition at the interface of a new phase. We consider an incoherent\nsecond-phase precipitate growing under the action of the stress field of a\nscrew dislocation. The second-phase growth rate as a function of the\nsupersaturation and a strain energy parameter is evaluated in spatial\ndimensions d=2 and d=3. Our calculations show that an increase in the amplitude\nof dislocation force, e.g. the magnitude of the Burgers vector, enhances the\nsecond-phase growth in an alloy. Moreover, a relationship linking the\nsupersaturation to the precipitate size in the presence of the elastic field of\ndislocation is calculated.",
        "positive": "Tight-binding Hamiltonians for Sr filled ruthenates: application to the\n  gap anisotropy and Hall coefficient in Sr2RuO4: Accurate orthogonal tight-binding Hamiltonians are constructed for\nferromagnetic SrRuO$_3$ and the layered perovskite superconductor,\nSr$_2$RuO$_4$ by fitting to all-electron full-potential local density band\nstructures obtained by the linearized augmented planewave method. These\nHamiltonians allow the band structure to be computed on very fine meshes in the\nBrillouin zone at low cost, and additionally have analytic band velocities,\nwhile retaining the accuracy of the full-potential electronic structure\ncalculations. This greatly facilitates calculation of transport and\nsuperconducting parameters related to the fermiology. These features are\nexploited to calculate the Hall coefficient and vortex lattice geometry for\nSr$_2$RuO$_4$ with fine integration meshes. We find the lower limit for the\ninterband order parameter anisotropy to be compatible with the observed square\ngeometry. We also find that the sign reversal of the Hall coefficient can be\nexplained in a conventional way if the bands are shifted by a few mRy so as to\nmatch the experimental de Haas-van Alphen areas exactly, {\\it and} the\ntemperature dependence of the relaxation time is strongly dependent on the band\ncharacter."
    },
    {
        "anchor": "Roto-flexoelectric coupling impact on the phase diagrams and\n  pyroelectricity of thin SrTiO3 films: The influence of the flexoelectric and rotostriction coupling on the phase\ndiagrams of ferroelastic-quantum paraelectric SrTiO3 films was studied using\nLandau-Ginzburg-Devonshire (LGD) theory. The phase diagrams in coordinates\ntemperature - film thickness were calculated for different epitaxial misfit\nstrains. Tensile misfit strains stimulate appearance of the spontaneous\nout-of-plane structural order parameter (displacement vector of an appropriate\noxygen atom from its cubic position) in the structural phase. Compressive\nmisfit strains stimulate appearance of the spontaneous in-plane structural\norder parameter. Gradients of the structural order parameter components, which\ninevitably exist in the vicinity of film surfaces due to the termination and\nsymmetry breaking, induce improper polarization and pyroelectric response via\nthe flexoelectric and rotostriction coupling mechanism. Flexoelectric and\nrotostriction coupling results in the roto-flexoelectric field that is\nantisymmetric inside the film, small in the central part of the film, where the\ngradients of the structural parameter are small, and maximal near the surfaces,\nwhere the gradients of the structural parameter are highest. The field induces\nimproper polarization and pyroelectric response. Penetration depths of the\nimproper phases (both polar and structural) can reach several nm from the film\nsurfaces. An improper pyroelectric response of thin films is high enough to be\nregistered with planar-type electrode configurations by conventional\npyroelectric methods.",
        "positive": "Deterministic Generation and Guided Motion of Magnetic Skyrmions by\n  Focused He$^+$-Ion Irradiation: Magnetic skyrmions are quasiparticles with non-trivial topology, envisioned\nto play a key role in next-generation data technology while simultaneously\nattracting fundamental research interest due to their emerging topological\ncharge. In chiral magnetic multilayers, current-generated spin-orbit torques or\nultrafast laser excitation can be used to nucleate isolated skyrmions on a\npicosecond timescale. Both methods, however, produce randomly arranged\nskyrmions, which inherently limits the precision on the location at which the\nskyrmions are nucleated. Here, we show that nanopatterning of the anisotropy\nlandscape with a He$^+$-ion beam creates well-defined skyrmion nucleation\nsites, thereby transforming the skyrmion localization into a deterministic\nprocess. This approach allows to realize control of individual skyrmion\nnucleation as well as guided skyrmion motion with nanometer-scale precision,\nwhich is pivotal for both future fundamental studies of skyrmion dynamics and\napplications."
    },
    {
        "anchor": "Unconventional aspects of electronic transport in delafossite oxides: The electronic transport properties of the delafossite oxides ABO$_2$ are\nusually understood in terms of two well separated entities, namely, the\ntriangular A$^+$ and (BO$_2$)$^-$ layers. Here we review several cases among\nthis extensive family of materials where the transport depends on the\ninterlayer coupling and displays unconventional properties. We review the doped\nthermoelectrics based on CuRhO$_2$ and CuCrO$_2$, which show a high-temperature\nrecovery of Fermi-liquid transport exponents, as well as the highly anisotropic\nmetals PdCoO$_2$, PtCoO$_2$ and PdCrO$_2$ where the sheer simplicity of the\nFermi surface leads to unconventional transport. We present some of the\ntheoretical tools that have been used to investigate these transport properties\nand review what can and cannot be learned from the extensive set of electronic\nstructure calculations that have been performed.",
        "positive": "GaN and InN nanowires grown by MBE: a comparison: Morphological, optical and transport properties of GaN and InN nanowires\ngrown by molecular beam epitaxy (MBE) have been studied. The differences\nbetween the two materials in respect to growth parameters and optimization\nprocedure was stressed. The nanowires crystalline quality has been investigated\nby means of their optical properties. A comparison of the transport\ncharacteristics was given. For each material a band schema was shown, which\ntakes into account transport and optical features and is based on Fermi level\npinning at the surface."
    },
    {
        "anchor": "A multi-scale approach for magnetisation dynamics: Unraveling exotic\n  magnetic states of matter: Crystallographic lattice defects strongly influence dynamical properties of\nmagnetic materials at both microscopic and macroscopic length scales. A\nmulti-scale approach to magnetisation dynamics, which is presented in this\npaper, accurately captures such effects. The method is illustrated using\nexamples of systems with localized, non-trivial topological properties, e.g. in\nthe form of skyrmions and chiral domain walls that interact with lattice\ndislocations. Technical aspects of the methodology involve multi-scale\nmagnetisation dynamics that connects atomistic and continuum descriptions. The\ntechnique is capable of solving the Landau-Lifshitz-Gilbert equations\nefficiently in two regions of a magnetic material --- the mesoscopic and the\natomistic regions, which are coupled in a seamless way. It is demonstrated that\nthis methodology allows simulating realistically-sized magnetic skyrmions\ninteracting with material defects and novel physical effects, uncovered using\nthis theoretical methodology, are described.",
        "positive": "Thermodynamic and Relaxation Processes near Curie Point in Gadolinium: An experimental method is suggested for the determination of the rate of\nmagnetic phase transitions. The method is based on the measurement of the\nchange of magnetic susceptibility of a ferromagnetic sample in the vicinity of\nthe phase transition in response to an abrupt change of the sample temperature.\nThis paper describes the measurement of the change of the magnetic\nsusceptibility of a thin gadolinium plates, cooled by water-flow at a\ntemperature below the Curie point (Tc = 292 K). It was found that the\nrelaxation time of the magnetic susceptibility of gadolinium in the temperature\nrange from 289.9 to 291.3 K can be approximated using the Landau-Khalatnikov\nequation with a kinetic coefficient value gamma = 3.9x10-8 cm3/(ergxs). The\nlinear approximation does not fit well in the range from 291.3 to 293.2 K. The\nfundamental restriction of specific power of the magnetocaloric refrigerator\n(made by gadolinium plates) was estimated."
    },
    {
        "anchor": "Strain effects on ferroelectric polarization and magnetism in\n  orthorhombic HoMnO3: Aiming at increasing the ferroelectric polarization in AFM-E ortho-\\hmo, we\ninvestigate the in-plane strain effects on both the magnetic configuration and\nthe polarization by means of density functional theory calculations and model\nHamiltonian approaches. Our results show that the net polarization is largely\nenhanced under compressive strain, due to an increase of the electronic\ncontribution to the polarization, whereas the ionic contribution is found to\ndecrease. We identify the electron-lattice coupling, due to Jahn-Teller (JT)\ndistortions, and its response to strain to be responsible for the observed\nbehavior. The JT-induced orbital ordering of occupied Mn-e$_g^1$ electrons in\nalternating $3x^2-r^2/3y^2-r^2$ orbital states at equilibrium changes to a\nmixture with $x^2-z^2/y^2-z^2$ states under in-plane compressive strain. The\nasymmetric hopping of e$_g$ electrons between Mn ions along zig-zag spin chains\n(typical of the AFM-E spin configuration) is therefore enhanced under strain,\nexplaining the large value of the polarization. We reproduce the change in the\norbital ordering pattern in a degenerate double-exchange model supplemented\nwith electron-phonon interaction. In this picture, the orbital ordering change\nis related to a change of the Berry phase of the e$_g$ electrons, which in turn\ncauses an increase of the polarization, whose origin is purely electronic.",
        "positive": "Data-Driven Machine Learning to Predict Mechanical Properties of\n  Monolayer TMDs: The understanding of the material properties of the layered transition metal\ndichalcogenides (TMDs) is critical for their applications in structural\ncomposites. The data-driven machine learning (ML) based approaches are being\ndeveloped in contrast to traditional experimental or computational approach to\npredict and understand materials properties under varied operating conditions.\nIn this study, we used two ML algorithms such as Long Short-Term Memory (LSTM)\nand Feed Forward Neural Network (FFNN) combined with molecular dynamics (MD)\nsimulations to predict the mechanical properties of MX2 (M = Mo, W, and X = S,\nSe) TMDs. The LSTM model is found to be capable of predicting the entire\nstress-strain response whereas the FFNN is used to predict the material\nproperties such as fracture stress, fracture strain, and Young's modulus. The\neffects of operating temperature, chiral orientation, and pre-existing crack\nsize on the mechanical properties are thoroughly investigated. We carried out\n1440 MD simulations to produce the input dataset for the neural network models.\nOur results indicate that both LSTM and FFNN are capable of predicting the\nmechanical response of monolayer TMDs under different conditions with more than\n95% accuracy. The FFNN model exhibits lower computational cost than LSTM;\nhowever, the capability of LSTM model to predict the entire stress-strain curve\nis advantageous to assess material properties. The study paves the pathway\ntoward extending this approach to predict other important properties, such as\noptical, electrical, and magnetic properties of TMDs."
    },
    {
        "anchor": "Characterisation of the strain rate sensitivity of basal, prismatic and\n  pyramidal slip in Zircaloy-4 using micropillar compression: For polycrystalline deformation in metals such as Zircaloy-4, the slip\nstrength at different strain rates will control mechanical response and\nstrongly influence the anisotropy of plastic deformation. In this work, the\nslip activity and strain rate sensitivity of the <a> basal, <a> prismatic, and\n<c+a> pyramidal slip systems were explored by testing at variable strain rates\n(1E-4 s^-1 and 125 s^-1) using single crystal micropillar compression tests.\nThese systematic experiments enabled the direct fitting of the strain rate\nsensitivities of the different slip systems using a simple analytical model to\nreveal that deformation will be accommodated using different slip systems\ndepending on the strain rate of deformation in addition to the stress state\n(i.e. Schmid's law). This insight helps inform metal forming and understanding\nof the mechanical performance of these engineering alloys in the extremes of\nservice conditions.",
        "positive": "Mobility anisotropy in monolayer black phosphorus due to charged\n  impurities: We study the charged impurity limited mobility in black phosphorus, a highly\nanisotropic layered material. We compute the mobility within the Boltzmann\ntransport equation under detailed balance condition, and taking into account\nthe anisotropy in transport and electronic structure. For carrier densities\naccessible in experiments, we obtained an anisotropy ratio of 3 ~ 4 at zero\ntemperature, two-folds larger than that observed in experiments on multilayers\nsamples. We discuss also how the anisotropy depends on carrier density and\nimpurity distribution."
    },
    {
        "anchor": "Room-temperature stability of excitons and transverse-electric polarized\n  deep-ultraviolet luminescence in atomically thin GaN quantum wells: Quantum confinement profoundly affects the properties and interactions of\nelectrons, holes, and excitons in nanomaterials. We apply first-principles\ncalculations to study the effects of extreme quantum confinement on the\nelectronic, excitonic, and radiative properties of atomically thin GaN quantum\nwells with a thickness of 1 to 4 atomic monolayers embedded in AlN. We\ndetermine the quasiparticle band gaps, exciton energies and wave functions,\nradiative lifetimes, and Mott critical densities as a function of well and\nbarrier thickness. Our results show that quantum confinement in GaN monolayers\nincreases the band gap up to 5.44 eV and the exciton binding energy up 215 meV,\nindicating the thermal stability of excitons at room temperature. Exciton\nradiative lifetimes range from 1 to 3 nanoseconds at room temperature, while\nthe Mott critical density for exciton dissociation is approximately 10$^{13}$\ncm$^{-2}$. The luminescence is transverse-electric polarized, which facilitates\nlight extraction from c-plane heterostructures. We also introduce a simple\napproximate model for calculating the exciton radiative lifetime based on the\nfree-carrier bimolecular radiative recombination coefficient and the exciton\nradius, which agrees well with our results obtained with the Bethe-Salpeter\nequation predictions. Our results demonstrate that atomically thin GaN quantum\nwells exhibit stable excitons at room temperature for potential applications in\nefficient light emitters in the deep ultraviolet, as well as room-temperature\nexcitonic devices.",
        "positive": "A beginner's guide to the modern theory of polarization: The so-called {\\it Modern Theory of Polarization}, which rigorously defines\nthe spontaneous polarization of a period solid and provides a route for its\ncomputation in electronic structure codes through the Berry phase, is\nintroduced in a simple qualitative discussion."
    },
    {
        "anchor": "Synchrotron radiation induced magnetization in magnetically-doped and\n  pristine topological insulators: Quantum mechanics postulates that any measurement influences the state of the\ninvestigated system. Here, by means of angle-, spin-, and time-resolved\nphotoemission experiments and ab initio calculations we demonstrate how\nnon-equal depopulation of the Dirac cone (DC) states with opposite momenta in\nV-doped and pristine topological insulators (TIs) created by a photoexcitation\nby linearly polarized synchrotron radiation (SR) is followed by the\nhole-generated uncompensated spin accumulation and the SR-induced magnetization\nvia the spin-torque effect. We show that the photoexcitation of the DC is\nasymmetric, that it varies with the photon energy, and that it practically does\nnot change during the relaxation. We find a relation between the\nphotoexcitation asymmetry, the generated spin accumulation and the induced spin\npolarization of the DC and V 3d states. Experimentally the SR-generated\nin-plane and out-of-plane magnetization is confirmed by the\n$k_{\\parallel}$-shift of the DC position and by the splitting of the states at\nthe Dirac point even above the Curie temperature. Theoretical predictions and\nestimations of the measurable physical quantities substantiate the experimental\nresults.",
        "positive": "Penetration depth of Cooper pairs in the IrMn antiferromagnet: Suppression of superconductivity due to the proximity effect between a\nsuperconductor and a ferromagnet can be partially alleviated when a Cooper pair\nsimultaneously samples different directions of the short-range exchange field.\nThe superconductor's critical temperature, TC, is therefore expected to\npartially recover when the ferromagnet is in a multi-domain state, as opposed\nto a single-domain state. Here, we discuss series of experiments performed with\nferromagnet(Pt/Co)/spacer(IrMn and Pt)/superconductor(NbN) heterostructures. By\ntuning the various parameters in play, e.g., superconducting coherence\nlength-to-thicknesses ratio, and domain sizes, we obtained up to 10 percent\nrecovery of the superconducting critical temperature {\\Delta}TC/TC. This\nlarge-scale recovery made novel investigations possible. In particular, from\nthe spacer thickness-dependence of {\\Delta}TC/TC, it was possible to deduce the\ncharacteristic length for Cooper pair penetration in an IrMn antiferromagnet.\nThis information is crucial for electronic transport, and up to now has been\ndifficult to access experimentally for antiferromagnets."
    },
    {
        "anchor": "Spin Transfer Torque and Tunneling Magnetoresistance Dependences on the\n  Finite Bias Voltages and Insulator Barrier Energy: We investigate the dependence of perpendicular and parallel spin transfer\ntorque (STT) and tunneling magnetoresistance (TMR) on the insulator barrier\nenergy in the magnetic tunnel junction (MTJ). We employed single orbit tight\nbinding model combined with the Keldysh non-equilibrium Green's function method\nin order to calculate the perpendicular and parallel STT, and TMR in MTJ with\nthe finite bias voltages. The dependences of STT and TMR on the insulator\nbarrier energy are calculated for the semi-infinite half metallic ferromagnetic\nelectrodes. We find that perfect linear relation between the parallel STT and\nthe tunneling current for the wide range of the insulator barrier energy.\nFurthermore, the TMR also depends on the insulator barrier energy, which\ncontradicts to the Julliere's simple model.",
        "positive": "Realization of epitaxial ZnO layers on GaP(111) substrates by pulsed\n  laser deposition: Epitaxy of ZnO layers on cubic GaP (111) substrates has been demonstrated\nusing pulsed laser deposition. Out of plane and in-plane epitaxial relationship\nof ZnO layer with respect to GaP substrate determined using phi scans in high\nresolution X-ray diffraction measurements are (0001) ZnO || (111) GaP and (-1 2\n-1 0) ZnO || (-1 1 0) GaP respectively. Our results of epitaxy of ZnO and its\nintense excitonic photoluminescence with very weak defect luminescence suggest\nthat (111) oriented GaP can be a potential buffer layer choice for the\nintegration of ZnO based optoelectronic devices on Si(111) substrates."
    },
    {
        "anchor": "Total energies from variational functionals of the Green function and\n  the renormalized four-point vertex: We derive variational expressions for the grand potential or action in terms\nof the many-body Green function $G$ which describes the propagation of\nparticles and the renormalized four-point vertex $\\Gamma$ which describes the\nscattering of two particles in many-body systems. The main ingredient of the\nvariational functionals is a term we denote as the $\\Xi$-functional which plays\na role analogously to the usual $\\Phi$-functional studied by Baym (G.Baym,\nPhys.Rev. 127, 1391 (1962)) in connection with the conservation laws in\nmany-body systems. We show that any $\\Xi$-derivable theory is also\n$\\Phi$-derivable and therefore respects the conservation laws. We further set\nup a computational scheme to obtain accurate total energies from our\nvariational functionals without having to solve computationally expensive sets\nof self-consistent equations. The input of the functional is an approximate\nGreen function $\\tilde{G}$ and an approximate four-point vertex\n$\\tilde{\\Gamma}$ obtained at a relatively low computational cost. The\nvariational property of the functional guarantees that the error in the total\nenergy is only of second order in deviations of the input Green function and\nvertex from the self-consistent ones that make the functional stationary. The\nfunctionals that we will consider for practical applications correspond to\ninfinite order summations of ladder and exchange diagrams and are therefore\nparticularly suited for applications to highly correlated systems. Their\npractical evaluation is discussed in detail.",
        "positive": "Domain-knowledge-aided machine learning method for properties prediction\n  of soft magnetic metallic glasses: A machine learning (ML) method aided by domain knowledge was proposed to\npredict saturated magnetization (Bs) and critical diameter (Dmax) of soft\nmagnetic metallic glass (MGs). Two datasets were established based on published\nexperimental works about soft magnetic MGs. A general feature space was\nproposed and proved to be adaptive for ML model training for different\nprediction tasks. It was found that the predictive performance of ML models was\nbetter than traditional physical knowledge-based estimation methods. In\naddition, domain knowledge aided feature selection can greatly reduce the\nnumber of features without significantly reducing the prediction accuracy.\nFinally, binary classification of the critical size of soft magnetic metallic\nglass was studied."
    },
    {
        "anchor": "Negative Differential Resistivity and Positive Temperature Coefficient\n  of Resistivity effect in the diffusion limited current of ferroelectric thin\n  film capacitors: We present a model for the leakage current in ferroelectric thin- film\ncapacitors which explains two of the observed phenomena that have escaped\nsatisfactory explanation, i.e. the occurrence of either a plateau or negative\ndifferential resistivity at low voltages, and the observation of a Positive\nTemperature Coefficient of Resistivity (PTCR) effect in certain samples in the\nhigh-voltage regime. The leakage current is modelled by considering a\ndiffusion-limited current process, which in the high-voltage regime recovers\nthe diffusion-limited Schottky relationship of Simmons already shown to be\napplicable in these systems.",
        "positive": "Roughening and pinning of interface cracks in shear delamination of thin\n  films: We investigate the roughening of shear cracks running along the interface\nbetween a thin film and a rigid substrate. We demonstrate that short-range\ncorrelated fluctuations of the interface strength lead to self-affine\nroughening of the crack front as the driving force (the applied shear\nstress/stress intensity factor) increases towards a critical value. We\ninvestigate the disorder-induced perturbations of the crack displacement field\nand crack energy, and use the results to determine the crack pinning force and\nto assess the shape of the critical crack. The analytical arguments are\nvalidated by comparison with simulations of interface cracking."
    },
    {
        "anchor": "Magnetic anisotropy modulation of magnetite in Fe3O4/BaTiO3(100)\n  epitaxial structures: Temperature dependent magnetometry and transport measurements on epitaxial\nFe3O4 films grown on BaTiO3(100) single crystals by molecular beam epitaxy show\na series of discontinuities, that are due to changes in the magnetic anisotropy\ninduced by strain in the different crystal phases of BaTiO3. The magnetite film\nis under tensile strain at room temperature, which is ascribed to the lattice\nexpansion of BaTiO3 at the cubic to tetragonal transition, indicating that the\nmagnetite film is relaxed at the growth temperature. From the magnetization\nversus temperature curves, the variation in the magnetic anisotropy is\ndetermined and compared with the magnetoelastic anisotropies. These results\ndemonstrate the possibility of using the piezoelectric response of BaTiO3 to\nmodulate the magnetic anisotropy of magnetite films.",
        "positive": "Periodicity-dependence of the ferroelectric properties in BiFeO3/SrTiO3\n  multiferroic superlattices: Artificial superlattices of (BiFeO3)m(SrTiO3)m (m= 1 to 10 unit cells)\nconsisting of multiferroic BiFeO3 and insulating SrTiO3 layers were fabricated\non (100)-oriented SrTiO3 substrates by pulsed laser ablation. The remnant\npolarization and leakage current behavior were studied varying the periodicity\n(8-80A) of the superlattice. The leakage current was reduced by few orders of\nmagnitude on increase of periodicity compared to single layer BiFeO3 thin\nfilms. Reduced leakage and intrinsic polarization hysteresis was observed and\nwas confirmed by PUND analysis for periodicities in the range 20-60A. The\nleakage current was observed to be dominated by space charge limited conduction"
    },
    {
        "anchor": "Temperature controlled L\u00e9vy flights of minority carriers in\n  photoexcited bulk n-InP: We study the spatial distribution of minority carriers arising from their\nanomalous photon-assisted diffusion upon photo-excitation at an edge of n-InP\nslab for temperatures ranging from 300 K to 78 K. The experiment provides a\nrealization of the \"L\\'evy flight\" random walk of holes, in which the L\\'evy\ndistribution index gamma is controlled by the temperature. We show that the\nvariation \\gamma(T) is close to that predicted earlier on the basis of the\nassumed quasi-equilibrium (van Roosbroek-Shockley) intrinsic emission spectrum,\n\\gamma=1-\\Delta /kT, where \\Delta(T) is the Urbach tailing parameter of the\nabsorption spectra. The decreasing \\gamma at lower temperatures results in a\ngiant enhancement in the spread of holes -- over distances exceeding 1 cm from\nthe region of photo-excitation.",
        "positive": "Parameter-free prediction of phase transition in PbTiO3 through\n  combination of quantum mechanics and statistical mechanics: Thermodynamics of ferroelectric materials and their ferroelectric to\nparaelectric (FE-PE) transitions including those in PbTiO3 is commonly\ndescribed by the phenomenological Landau theory and more recently by effective\nHamiltonian and various potentials, all with model parameters fitted to\nexperimental or theoretical data. Here we show that the zentropy theory, which\nconsiders the total entropy of a system as a weighted sum of entropies of\nconfigurations that the system may experience and the statistical entropy among\nthe configurations, can predict the FE-PE transition without fitting\nparameters. For PbTiO3, the configurations are identified as the FE\nconfigurations with 90- or 180-degree domain walls in addition to the ground\nstate of the FE configuration without domain wall. With the domain wall\nenergies predicted from first-principles calculations based on the density\nfunctional theory in the literature as the only inputs, the FE-PE transition\nfor PbTiO3 is predicted showing remarkable agreement with experiments,\nunveiling the microscopic fundamentals of the transition."
    },
    {
        "anchor": "Thermal Conductivity Measurements in Nanosheets via Bolometric Effect: Thermal conductivity measurement techniques for materials with nanoscale\ndimensions require fabrication of very complicated devices or their\napplicability is limited to a class of materials. Discovery of new methods with\nhigh thermal sensitivity are required for the widespread use of thermal\nconductivity measurements in characterizing materials properties. We propose\nand demonstrate a simple non-destructive method with superior thermal\nsensitivity to measure the in-plane thermal conductivity of nanosheets and\nnanowires using the bolometric effect. The method utilizes laser beam heating\nto create a temperature gradient, as small as a fraction of a Kelvin, over the\nsuspended section of the nanomaterial with electrical contacts. Local\ntemperature rise due to the laser irradiation alters the electrical resistance\nof the device, which can be measured precisely. This resistance change is then\nused to extract the temperature profile along the nanomaterial using thermal\nconductivity as a fitting parameter. We measured the thermal conductivity of\nV2O3 nanosheets to validate the applicability of the method and found an\nexcellent agreement with the literature. Further, we measured the thermal\nconductivity of metallic 2H-TaS2 for the first time and performed ab initio\ncalculations to support our measurements. Finally, we discussed the\napplicability of the method on semiconducting nanosheets and performed\nmeasurements on WS2 and MoS2 thin flakes.",
        "positive": "Ground-state structure of the hydrogen double vacancy on Pd(111): We determine the ground-state structure of a double vacancy in a hydrogen\nmonolayer on the Pd(111) surface. We represent the double vacancy as a triple\nvacancy containing one additional hydrogen atom. The potential-energy surface\nfor a hydrogen atom moving in the triple vacancy is obtained by\ndensity-functional theory, and the wave function of the fully quantum hydrogen\natom is obtained by solving the Schr\\\"odinger equation. We find that an H atom\nin a divacancy defect experiences significant quantum effects, and that the\nground-state wave function is centered at the hcp site rather than the fcc site\nnormally occupied by H atoms on Pd(111). Our results agree well with scanning\ntunneling microscopy images."
    },
    {
        "anchor": "A theoretical analysis of inertia-like switching in magnets:\n  applications to a synthetic antiferromagnet: The magnetization dynamics of a synthetic antiferromagnet subject to a short\nmagnetic field pulse, has been studied by using a combination of\nfirst-principles and atomistic spin dynamics simulations. We observe switching\nphenomena on the time scale of tens of picoseconds, and inertia-like behavior\nin the magnetization dynamics. We explain the latter in terms of a dynamic\nredistribution of magnetic energy from the applied field pulse to other\npossible energy terms, such as the exchange interaction and the magnetic\nanisotropy, without invoking concepts such as inertia of an antiferromagnetic\nvector. We also demonstrate that such dynamics can also be observed in a\nferromagnetic material where the incident field pulse pumps energy to the\nmagnetic anisotropy.",
        "positive": "First-principles study of the temperature-pressure phase diagram of\n  BaTiO3: We investigate the temperature-pressure phase diagram of BaTiO_3 using a\nfirst-principles effective-Hamiltonian approach. We find that the zero-point\nmotion of the ions affects the form of the phase diagram dramatically.\nSpecifically, when the zero-point fluctuations are included in the\ncalculations, all the polar (tetragonal, orthorhombic, and rhombohedral) phases\nof BaTiO_3 survive down to 0 K, while only the rhombohedral phase does\notherwise. We provide a simple explanation for this behavior. Our results\nconfirm the essential correctness of the phase diagram proposed by Ishidate et\nal. (Phys. Rev. Lett. 78, 2397 (1997))."
    },
    {
        "anchor": "Spectroscopic Neutron Imaging for Resolving Hydrogen Dynamics Changes in\n  Battery Electrolytes: We present spectroscopic neutron imaging (SNI), a bridge between imaging and\nscattering techniques, for the analysis of hydrogenated molecules in\nlithium-ion cells. The scattering information of CHn-based organic solvents and\nelectrolytes was mapped in two-dimensional space by investigating the\nwavelength-dependent property of hydrogen atoms through time-of-flight imaging.\nOur investigation demonstrates a novel approach to detect physical and chemical\nchanges in hydrogenated liquids, which extends, but not limits, the use of SNI\nto relevant applications in electrochemical devices, e.g., the study of\nelectrolytes in Li-ion batteries.",
        "positive": "Phase stability, chemical bonding and mechanical properties of titanium\n  nitrides: A first-principles study: We have performed first-principles evolutionary searches for all stable\ntitanium nitrides and have found, in addition to the well-known rocksalt-type\nTiN, new ground states Ti$_3$N$_2$, Ti$_4$N$_3$, Ti$_6$N$_5$ at atmospheric\npressure, and Ti$_2$N and TiN$_2$ at higher pressures. The latest nitrogen-rich\nstructure presents encapsulated N$_2$ dumbbells with a N-N distance of 1.348\n{\\AA} at 60 GPa and TiN$_2$ is predicted to be mechanically stable\n(quenchable). Our calculations of the mechanical properties (bulk modulus,\nshear modulus, Young's modulus, Poisson's ratio, and hardness) are in excellent\nagreement with the available experimental data and show that the hardness of\ntitanium nitrides increases with increasing nitrogen content. The hardness of\ntitanium nitrides is enhanced by strengthening directional covalent bonds and\ndisappearance of Ti-Ti metallic bonds. Among the predicted compounds, TiN$_2$\nhas the highest hardness of 27.2 GPa."
    },
    {
        "anchor": "Atomic structure and energetics of large vacancies in graphene: We present a computational study on the topology, energetics and structural\ndeformations for a large number of experimentally observed defect\nconfigurations in graphene. We find that both the number of lost hexagonal\ncarbon rings and introduced non-hexagonal rings increase linearly as a function\nof the vacancy order (number of missing atoms). The formation energies of the\ndefects increase by about 2.2 eV per missing atom after an initial offset,\nestablishing these defects as the lowest energy vacancy configurations studied\nin graphene to date. In addition, we find that even small point defects, which\nhave been until now assumed flat, cause graphene to bend out of plane when not\nrestricted into prohibitively confined geometries. This effect reaches to\nrelative long distances even for some of the smallest defects, significantly\nreducing the stress otherwise imposed on the surrounding lattice.",
        "positive": "Carbamazepine solubility in supercritical CO$_2$: a comprehensive study: In this paper we present our study of carbamazepine solubility in\nsupercritical carbon dioxide. We have calculated the solubility values along\ntwo isochores corresponding to the CO$_2$ densities $\\rho = 1.1\\rho_{cr}(CO_2)$\nand $\\rho= 1.3\\rho_{cr}(CO_2)$, where $\\rho_{cr}(CO_2)$ is the critical density\nof CO$_2$, in the temperature range from $313$ to $383~K$, as well as along\nthree isotherms at $T=318$, $328$ and $348~K$ by an approach based on the\nclassical density functional theory. The solubility values were also obtained\nusing in situ IR spectroscopy and molecular dynamics simulations along the\nmentioned isochores and isotherms, respectively. Because the density functional\ntheory only takes into account the Lennard-Jones interactions, it can be\nexpected to underestimate the solubility values when compared to the\nexperimental ones. However, we have shown that the data calculated within the\nclassical density functional theory qualitatively reproduce the solubility\ntrends obtained by IR spectroscopy and molecular dynamics simulation. Moreover,\nthe obtained position of the upper crossover pressure is in good agreement with\nthe experimental literature results."
    },
    {
        "anchor": "Controllable selective exfoliation of high-quality graphene nanosheets\n  and nanodots by ionic liquid assisted grinding: Bulk quantities of graphene nanosheets and nanodots have been selectively\nfabricated by mechanical grinding exfoliation of natural graphite in a small\nquantity of ionic liquids. The resulting graphene sheets and dots are solvent\nfree with low levels of naturally absorbed oxygen, inherited from the starting\ngraphite. The sheets are only two to five layers thick. The graphene nanodots\nhave diameters in the range of 9-29 nm and heights in the range of 1-16 nm,\nwhich can be controlled by changing the processing time.",
        "positive": "Elastic properties of self-folded two-dimensional nanomaterials: a\n  theoretical model validated by molecular dynamics simulations: The trade-off between strength and ductility has plagued the design of\nmacroscopic assemblies of two-dimensional materials for a long time. In order\nto break the strength-ductility paradox, the design of self-folded\ntwo-dimensional nanomaterial (SF-2DNM) has been recently proposed with the\ninspiration from the folded nanostructures of natural silks. Such folding\nstrategy is revealed to greatly enhance the ductility of overall assembly\nwithout much sacrifice of the excellent tensile strength of two-dimensional\nmaterials. However, the dependences of the elastic properties of SF-2DNMs on\nthe material properties of building blocks and the geometries of folded\nstructures have not been specifically clarified in previous studies. In this\npaper, we thus develop a theoretical model to describe the elastic properties\nof SF-2DNMs based on the shear-lag analysis. The load transfer behaviors and\nfailure modes of SF-2DNMs are demonstrated with this model. The Young's modulus\nand tensile strength of SF-2DNMs are also predicted, further validated by\nmolecular dynamics simulations. This model brings insights into the elastic\ndeformation of SF-2DNMs under external tension. The structure-property\nrelationship revealed by this model would provide useful guidelines for the\nrational design of SF-2DNMs in engineering applications."
    },
    {
        "anchor": "A Convection Chamber for Measuring Ice Crystal Growth Dynamics: We present the design of a general-purpose convection chamber that produces a\nstable environment for studying the growth of ice crystals from water vapor in\nthe presence of a background gas. Crystals grow in free fall inside the\nchamber, where the temperature and supersaturation are well characterized and\nsurprisingly uniform. As crystals fall and land on a substrate, their\ndimensions are measured using direct imaging and broad-band interferometry. We\nalso present a parameterized model of the supersaturation inside the chamber\nthat is based on differential hygrometer measurements. Using this chamber, we\nare able to observe the growth and morphology of ice crystals over a broad\nrange of conditions, as a function of temperature, supersaturation, gas\nconstituents, gas pressure, growth time, and other parameters.",
        "positive": "Exploring Dielectric Properties in Models of Amorphous Boron Nitride: We report a theoretical study of dielectric properties of models of amorphous\nBoron Nitride, using interatomic potentials generated by machine learning. We\nfirst perform first-principles simulations on small (about $100$ atoms in the\nperiodic cell) sample sizes to explore the emergence of mid-gap states and its\ncorrelation with structural features. Next, by using a simplified tight-binding\nelectronic model, we analyse the dielectric functions for complex three\ndimensional models (containing about $10.000$ atoms) embedding varying\nconcentrations of ${\\rm sp^{1}, sp^{2}}$ and ${\\rm sp^3}$ bonds between B and N\natoms. Within the limits of these methodologies, the resulting value of the\nzero-frequency dielectric constant is shown to be influenced by the population\ndensity of such mid-gap states and their localization characteristics. We\nobserve nontrivial correlations between the structure-induced electronic\nfluctuations and the resulting dielectric constant values. Our findings are\nhowever just a first step in the quest of accessing fully accurate dielectric\nproperties of as-grown amorphous BN of relevance for interconnect technologies\nand beyond."
    },
    {
        "anchor": "Charge pumping in magnetic tunnel junctions: Scattering theory: We study theoretically the charge transport pumped by magnetization dynamics\nthrough epitaxial FIF and FNIF magnetic tunnel junctions (F: Ferromagnet, I:\nInsulator, N: Normal metal). We predict a small but measurable DC pumping\nvoltage under ferromagnetic resonance conditions for collinear magnetization\nconfigurations, which may change sign as function of barrier parameters. A much\nlarger AC pumping voltage is expected when the magnetizations are at right\nangles. Quantum size effects are predicted for an FNIF structure as a function\nof the normal layer thickness.",
        "positive": "Large group delay in a microwave metamaterial analogue of\n  electromagnetically induced transparency: We report on our experimental work concerning a planar metamaterial\nexhibiting classical electromagnetically induced transparency (EIT). Using a\nstructure with two mirrored split-ring resonators as the dark element and a cut\nwire as the radiative element, we demonstrate that an EIT-like resonance can be\nachieved without breaking the symmetry of the structure. The mirror symmetry of\nthe metamaterial's structural element results in a selection rule inhibiting\nmagnetic dipole radiation for the dark element, and the increased quality\nfactor leads to low absorption (<10%) and large group index (of the order of\n30)."
    },
    {
        "anchor": "The theoretical DFT study of electronic structure of thin Si/SiO2\n  quantum nanodots and nanowires: The atomic and electronic structure of a set of proposed thin (1.6 nm in\ndiameter) silicon/silica quantum nanodots and nanowires with narrow interface,\nas well as parent metastable silicon structures (1.2 nm in diameter), was\nstudied in cluster and PBC approaches using B3LYP/6-31G* and PW PP LDA\napproximations. The total density of states (TDOS) of the smallest\nquasispherical silicon quantum dot (Si85) corresponds well to the TDOS of the\nbulk silicon. The elongated silicon nanodots and 1D nanowires demonstrate the\nmetallic nature of the electronic structure. The surface oxidized layer opens\nthe bandgap in the TDOS of the Si/SiO2 species. The top of the valence band and\nthe bottom of conductivity band of the particles are formed by the silicon core\nderived states. The energy width of the bandgap is determined by the length of\nthe Si/SiO2 clusters and demonstrates inverse dependence upon the size of the\nnanostructures. The theoretical data describes the size confinement effect in\nphotoluminescence spectra of the silica embedded nanocrystalline silicon with\nhigh accuracy.",
        "positive": "Advances in actinide thin films: synthesis, properties, and future\n  directions: Actinide-based compounds exhibit unique physics due to the presence of 5f\nelectrons, and serve in many cases as important technological materials.\nTargeted thin film synthesis of actinide materials has been successful in\ngenerating high-purity specimens in which to study individual physical\nphenomena. These films have enabled the study of the unique electron\nconfiguration, strong mass renormalization, and nuclear decay in actinide\nmetals and compounds. The growth of these films, as well as their\nthermophysical, magnetic, and topological properties, have been studied in a\nrange of chemistries, albeit far fewer than most classes of thin film systems.\nThis relative scarcity is the result of limited source material availability\nand safety constraints associated with the handling of radioactive materials.\nHere, we review recent work on the synthesis and characterization of\nactinide-based thin films in detail, describing both synthesis methods and\nmodelling techniques for these materials. We review reports on\npyrometallurgical, solution-based, and vapor deposition methods. We highlight\nthe current state-of-the-art in order to construct a path forward to higher\nquality actinide thin films and heterostructure devices."
    },
    {
        "anchor": "Determinative Role of the Jahn-Teller Disorder in the Raman Scattering\n  of Mixed-Valence Manganites: The mixed-valence perovskitelike manganites are characterized by unique\ninterrelation of Jahn-Teller distortions, electric and magnetic properties. The\nJahn-Teller distortion follows the Mn(3+)->Mn(4+) charge transfer with some\ndelay. Its development depends on the lifetime of Mn in (3+) state, governed by\nthe Mn(4+)/Mn(3+) ratio and magnetic correlation. The non-coherence of\nJahn-Teller distortions in orthorhombic mixed-valence manganites and\nrhombohedral RMnO3 (R = rare earth) results in oxygen disorder. We demonstrate\nthat the Raman spectra in this case are dominated by disorder-induced bands\nreflecting the oxygen partial phonon density of states (PDOS). The PDOS origin\nof the main Raman bands in insulating phases of such compounds is evidenced by\nthe similar lineshape of experimental spectra and calculated smeared PDOS and\ndisappearance of the PDOS bands in ordered ferromagnetic metallic phase.",
        "positive": "Three real-space discretization techniques in electronic structure\n  calculations: A characteristic feature of the state-of-the-art of real-space methods in\nelectronic structure calculations is the diversity of the techniques used in\nthe discretization of the relevant partial differential equations. In this\ncontext, the main approaches include finite-difference methods, various types\nof finite-elements and wavelets. This paper reports on the results of several\ncode development projects that approach problems related to the electronic\nstructure using these three different discretization methods. We review the\nideas behind these methods, give examples of their applications, and discuss\ntheir similarities and differences."
    },
    {
        "anchor": "Effect of Mg substitution in Sr2SiO4:Eu2+ nanophosphors for blue and\n  white emission at near UV excitation: Nanophosphors of (Sr0.98-xMgxEu0.02)2SiO4 (x=0, 0.18, 0.38, 0.58 and 0.78)\nwere prepared through low temperature solution combustion method and their\nluminescence properties were studied. The emission peak for Eu2+ doped Sr2SiO4\nnanophosphor is observed at ~490 nm and ~553 nm corresponding to two Sr2+ sites\nSr(I) and Sr(II) respectively for 395 nm excitation but the addition of Mg2+\ndopant in Sr2SiO4 leads to suppression of ~553 nm emission peak due to absence\nof energy levels of Sr (II) sites which results in a single broad emission at\n~460nm. It was shown that the emission peak blue shifted with increase in Mg\nconcentration which may be attributed to change in crystal field environment\naround Sr(I) sites. Therefore the (Mg0.78Sr0.20Eu0.02)2SiO4: Eu2+ nanophosphor\ncan be used for blue emission and the Sr2SiO4:Eu0.042+ for green-yellow\nemission at 395 nm excitations. The CIE coordinates for mixed powders of\n(Mg0.78Sr0.20Eu0.02)2SiO4 and Sr2SiO4:Eu0.042+ (in 1: 1 ratio) falls in the\nwhite region demonstrating the possible use of the mixture in white light\ngeneration using near UV excitation source.",
        "positive": "Coherence and stiffness of spin waves in diluted ferromagnets: We present results of a numerical analysis of magnon spectra in supercells\nsimulating two-dimensional and bulk random diluted ferromagnets with\nlong-ranged pair exchange interactions. We show that low-energy spectral\nregions for these strongly disordered systems contain a coherent component\nleading to interference phenomena manifested by a pronounced sensitivity of the\nlowest excitation energies to the adopted boundary conditions. The dependence\nof configuration averages of these excitation energies on the supercell size\ncan be used for an efficient determination of the spin-wave stiffness D. The\ndeveloped formalism is applied to the ferromagnetic Mn-doped GaAs semiconductor\nwith optional incorporation of phosphorus; the obtained concentration trends of\nD are found in reasonable agreement with recent experiments. Moreover, a\nrelation of the spin stiffness to the Curie temperature Tc has been studied for\nMn-doped GaAs and GaN semiconductors. It is found that the ratio Tc/D exhibits\nqualitatively the same dependence on Mn concentration in both systems."
    },
    {
        "anchor": "Control of charge-spin interconversion in van der Waals heterostructures\n  with chiral charge density waves: A charge density wave (CDW) represents an exotic state in which electrons are\narranged in a long range ordered pattern in low-dimensional materials. Although\nour understanding of the fundamental character of CDW has been enriched after\nextensive studies, its relationship with functional phenomena remains\nrelatively limited. Here, we show an unprecedented demonstration of a tunable\ncharge-spin interconversion (CSI) in graphene/1T-TaS$_2$ van der Waals\nheterostructures by manipulating the distinct CDW phases in 1T-TaS$_2$. Whereas\nCSI from spins polarized in all three directions are observed in the\nheterostructure when the CDW phase does not show commensurability, the output\nof one of the components disappears and the other two are enhanced when the CDW\nphase becomes commensurate. The experimental observation is supported by\nfirst-principles calculations, which evidence that chiral CDW multidomains are\nat the origin of the switching of CSI. Our results uncover a new approach for\non-demand CSI in low-dimensional systems, paving the way for advanced\nspin-orbitronic devices.",
        "positive": "Effect of support on the vanadyl oxygen abstraction in supported vanadia: Supported vanadia catalysts are modeled within the cluster DFT approach to\nget an insight into the mechanism in which the support affects the activity of\nvanadia in the oxidation processes. The energy of the V=O group dissociation\nchosen as a descriptor of the oxidation activity is estimated using two aligned\ndivanadate V2O3(OH)4 particles at various distances. Separation between\nparticles allows to imitate (i) the various supporting materials (e.g. TiO2,\nSiO2, etc.), and (ii) the coverage of vanadia on a particular support. A\nsubstantial compensation of the energy loss upon the vanadyl oxygen abstraction\nvia bonding to the vanadyl oxygen of neighboring vanadate particle has been\npredicted. On account of such compensation the overall energy of the V=O\ndissociation reaches its minimal value of 36 kcal/mol (dropping from maximum of\n142 kcal/mol) at small separation of 3 {\\AA} between dimers when the nearest\nvanadyl oxygen occupies a bridge V-O-V position. For dimers separated by about\n4 {\\AA}, the dissociation energy achieves its maximal value for isolated dimers\nof about 143 kcal/mol. Thus, these findings allows one to conclude that the\noxygen mobility is a result of a compensation effect in a chain-like bonding\nbetween neighboring vanadyl groups on the surface of support."
    },
    {
        "anchor": "Optical spin injection and spin lifetime in Ge heterostructures: We demonstrate optical orientation in Ge/SiGe quantum wells and study their\nspin properties. The ultrafast electron transfer from the center of the\nBrillouin zone to its edge allows us to achieve high spin-polarization\nefficiencies and to resolve the spin dynamics of holes and electrons. The\ncircular polarization degree of the direct-gap photoluminescence exceeds the\ntheoretical bulk limit, yielding ~37% and ~85% for transitions with heavy and\nlight holes states, respectively. The spin lifetime of holes at the top of the\nvalence band is found to be ~0.5 ps and it is governed by transitions between\nheavy and light hole states. Electrons at the bottom of the conduction band, on\nthe other hand, have a spin lifetime that exceeds 5 ns below 150 K. Theoretical\nanalysis of the electrons spin relaxation indicates that phonon-induced\nintervalley scattering dictates the spin lifetime.",
        "positive": "Selective surface functionalization at regions of high local curvature\n  in graphene: Monolayer graphene was deposited on a Si wafer substrate decorated with SiO2\nnanoparticles (NPs) and then exposed to aryl radicals that were generated in\nsitu from their diazonium precursors. Using micro-Raman mapping, the aryl\nradicals were found to selectively react with the regions of graphene that\ncovered the NPs. The enhanced chemical reactivity was attributed to the\nincreased strain energy induced by the local mechanical deformation of the\ngraphene."
    },
    {
        "anchor": "Efficient Control of Magnetization Dynamics Via W/CuO$_\\text{x}$\n  Interface: Magnetization dynamics, which determine the speed of magnetization switching\nand spin information propagation, play a central role in modern spintronics.\nGaining its control will satisfy the different needs of various spintronic\ndevices. In this work, we demonstrate that the surface oxidized Cu\n(CuO$_\\text{x}$) can be employed for the tunability of magnetization dynamics\nof ferromagnet (FM)/heavy metal (HM) bilayer system. The capping CuO$_\\text{x}$\nlayer in CoFeB/W/CuO$_\\text{x}$ trilayer reduces the magnetic damping value in\ncomparison with the CoFeB/W bilayer. The magnetic damping even becomes lower\nthan that of the CoFeB/CuO$_\\text{x}$ by ~ 16% inferring the stabilization of\nanti-damping phenomena. Further, the reduction in damping is accompanied by a\nvery small reduction in the spin pumping-induced output DC voltage in the\nCoFeB/W/CuO$_\\text{x}$ trilayer. The simultaneous observation of anti-damping\nand spin-to-charge conversion can be attributed to the orbital Rashba effect\nobserved at the HM/CuO$_\\text{x}$ interface. Our experimental findings\nillustrate that the cost-effective CuO$_\\text{x}$ can be employed as an\nintegral part of modern spintronics devices owing to its rich underneath\nspin-orbital physics.",
        "positive": "Sr$_2$Cu(PO$_4$)$_2$: A real material realization of the 1D nearest\n  neighbor Heisenberg chain: We present evidence that crystalline Sr_2Cu(PO_4)_2 is a nearly perfect\none-dimensional (1D) spin-1/2 anti-ferromagnetic Heisenberg model (AHM) chain\ncompound with nearest neighbor only exchange. We undertake a broad theoretical\nstudy of the magnetic properties of this compound using first principles (LDA,\nLDA+U calculations), exact diagonalization and Bethe-ansatz methodologies to\ndecompose the individual magnetic contributions, quantify their effect, and fit\nto experimental data. We calculate that the conditions of one-dimensionality\nand short-ranged magnetic interactions are sufficiently fulfilled that Bethe's\nanalytical solution should be applicable, opening up the possibility to explore\neffects beyond the infinite chain limit of the AHM Hamiltonian. We begin such\nan exploration by examining some extrinsic effects such as impurities and\ndefects."
    },
    {
        "anchor": "The examination of stable charge states of vacancies in Cu2ZnSnS4: The stable charge states of vacancies in the solar cell absorber material\nCu2ZnSnS4 are investigated using Kohn-Sham (KS) defect-induced single particle\nlevels analysis by concerning the screened Coulomb hybrid functional. We found\nout that the Cu, Zn and S vacancies (denoted by VCu, VZn, VS) do not induce\nsingle particle defect levels in the vicinity of the band gap thus each of them\nhas only one stable charge state corresponding to the fully occupied valence\nband VCu1-, VZn2- and VS0, respectively (and therefore cannot account for any\ndefect transition energy levels). The Sn vacancy (VSn) has three stable charge\nstates VSn2-, VSn3- and VSn4-, which may account for two charge transition\nenergy levels. By comparing with previous charge transition energy levels\nstudies, our results indicate that the examination of stable charge states is a\nnecessary and important step which should be done before charge transition\nenergy levels calculations.",
        "positive": "Effect of kink-rounding barriers on step edge fluctuations: The effect that an additional energy barrier E_{kr} for step adatoms moving\naround kinks has on equilibrium step edge fluctuations is explored using\nscaling arguments and kinetic Monte Carlo simulations. When mass transport is\nthrough step edge diffusion, the time correlation function of the step\nfluctuations behaves as C(t) = A(T) t^{1/4}. At low temperatures the prefactor\nA(T) shows Arrhenius behavior with an activation energy (E_{det} + 3 epsilon)/4\nif E_{kr} < epsilon and (E_{det} + E_{kr} + 2 epsilon)/4 if E_{kr} > epsilon,\nwhere epsilon is the kink energy and E_{det} is the barrier for detachment of a\nstep adatom from a kink. We point out that the assumption of an Einstein\nrelation for step edge diffusion has lead to an incorrect interpretation of\nstep fluctuation experiments, and explain why such a relation does not hold.\nThe theory is applied to experimental results on Pt(111) and Cu(100)."
    },
    {
        "anchor": "Prediction and observation of the first antiferromagnetic topological\n  insulator: Despite immense advances in the field of topological materials, the\nantiferromagnetic topological insulator (AFMTI) state, predicted in 2010, has\nbeen resisting experimental observation up to now. Here, using density\nfunctional theory and Monte Carlo method we predict and by means of structural,\ntransport, magnetic, and angle-resolved photoemission spectroscopy measurements\nconfirm for the first time realization of the AFMTI phase, that is hosted by\nthe van der Waals layered compound MnBi$_2$Te$_4$. An interlayer AFM ordering\nmakes MnBi$_2$Te$_4$ invariant with respect to the combination of the\ntime-reversal ($\\Theta$) and primitive-lattice translation ($T_{1/2}$)\nsymmetries, $S=\\Theta T_{1/2}$, which gives rise to the $Z_2$ topological\nclassification of AFM insulators, $Z_2$ being equal to 1 for this material. The\n$S$-breaking (0001) surface of MnBi$_2$Te$_4$ features a giant bandgap in the\ntopological surface state thus representing an ideal platform for the\nobservation of such long-sought phenomena as the quantized magnetoelectric\ncoupling and intrinsic axion insulator state.",
        "positive": "Physical Model of Nernst Element: Generation of electric power by the Nernst effect is a new application of a\nsemiconductor. A key point of this proposal is to find materials with a high\nthermomagnetic figure-of-merit, which are called Nernst elements. In order to\nfind candidates of the Nernst element, a physical model to describe its\ntransport phenomena is needed. As the first model, we began with a parabolic\ntwo-band model in classical statistics. According to this model, we selected\nInSb as candidates of the Nernst element and measured their transport\ncoefficients in magnetic fields up to 4 Tesla within a temperature region from\n270K to 330K. In this region, we calculated transport coefficients numerically\nby our physical model. For InSb, experimental data are coincident with\ntheoretical values in strong magnetic field."
    },
    {
        "anchor": "Monolayer Solid Helium-4 Clusters on Graphite: In order to resolve the controversy about the low density region of the phase\ndiagram of the 4He monolayer on graphite, we have undertaken a path integral\nMonte Carlo study of the system. We provide direct evidence that the low\ndensity monolayer possesses solid clusters and a low density vapor as opposed\nto the most recent proposal that the system is in a superfluid phase. We\nfurther establish that the rounded heat capacity peaks observed at low\ndensities are caused by melting of such solid clusters and are not associated\nwith the suggested superfluid transition.",
        "positive": "Part I: Staggered index and 3D winding number of Kramers-degenerate\n  bands: For three-dimensional (3D) crystalline insulators, preserving space-inversion\n($\\mathcal{P}$) and time-reversal ($\\mathcal{T}$) symmetries, the third\nhomotopy class of two-fold, Kramers-degenerate bands is described by a 3D\nwinding number $n_{3,j} \\in \\mathbb{Z}$, where $j$ is the band index. It\ngoverns space group symmetry-protected, instanton or tunneling configurations\nof $SU(2)$ Berry connection, and the quantization of magneto-electric\ncoefficient $\\theta_j = n_{3,j} \\pi$. We show that $|n_{3,j}|$ for realistic,\n\\emph{ab initio} band structures can be identified from a staggered\nsymmetry-indicator $\\kappa_{AF,j} \\in \\mathbb{Z}$ and the gauge-invariant\nspectrum of $SU(2)$ Wilson loops. The procedure is elucidated for $4$-band and\n$8$-band tight-binding models and \\emph{ab initio} band structure of Bi, which\nis a $\\mathbb{Z}_2$-trivial, higher-order, topological crystalline insulator.\nWhen the tunneling is protected by $C_{nh}$ and $D_{nh}$ point groups, the\nproposed method can also identify the signed winding number $n_{3,j}$. Our\nanalysis distinguishes between magneto-electrically trivial ($\\theta=0$) and\nnon-trivial ($\\theta=2 s \\pi$, with $s \\neq 0$) topological crystalline\ninsulators. In Part II, we demonstrate $\\mathbb{Z}$-classification of $\\theta$\nby computing induced electric charge (Witten effect) on magnetic Dirac\nmonopoles."
    },
    {
        "anchor": "Magnetic properties of ultra-thin 3d transition-metal binary alloys I:\n  spin and orbital moments, anisotropy, and confirmation of Slater-Pauling\n  behavior: The structure and static magnetic properties - saturation magnetization,\nperpendicular anisotropy, spectroscopic g-factor, and orbital magnetization -\nof thin-film 3d transition metal alloys are determined over the full range of\nalloy compositions via X-ray diffraction, magnetometry, and ferromagnetic\nresonance measurements. We determine the interfacial perpendicular magnetic\nanisotropy by use of samples sets with varying thickness for specific alloy\nconcentrations. The results agree with prior published data and theoretical\npredictions. They provide a comprehensive compilation of the magnetic\nproperties of thin-film Ni-Co, Ni-Fe and Co-Fe alloys that goes well beyond the\noften-cited Slater-Pauling dependence of magnetic moment on alloy\nconcentration.",
        "positive": "A nucleation theory for yielding of nearly defect-free crystals:\n  understanding rate dependent yield points: Experiments and simulations show that when an initially defect free rigid\ncrystal is subjected to deformation at a constant rate, irreversible plastic\nflow commences at the so-called {\\em yield point}. The yield point is a weak\nfunction of the deformation rate, which is usually expressed as a power law\nwith an extremely small non-universal exponent. We re-analyze a representative\nset of published data on nanometer sized, mostly defect free, Cu, Ni and Au\ncrystals in the light of a recently proposed theory of yielding based on\nnucleation of stable stress-free regions inside the metastable rigid solid. The\nsingle relation derived here, which is {\\em not} a power law, explains data\ncovering {\\em fifteen} orders of magnitude in time scales."
    },
    {
        "anchor": "Detection of light emission produced in the process of positronium\n  formation: The excess energy emitted during the positronium (Ps) formation in condensed\nmatter may be released as light. Spectroscopic analysis of this light can be a\nnew method of studying the electronic properties of materials. We report the\nfirst experimental attempt, according to our knowledge, to verify the existence\nof this emission process. As a result, the possibility of the emission of\nphotons during Ps formation is within the experimental uncertainty in two\ndifferent solids: an n-alkane and porous silica. However, it seems that the Ps\nformation on the alkane surface is not accompanied by the emission of photons\nwith energy in the detection range of 1.6 - 3.9 eV. Various processes that can\ninfluence the energy of the photon emitted during the Ps formation are\ndiscussed to elucidate this issue. To aid future experiments, equations were\ndeveloped to estimate the expected ratio of light emission events to\nannihilation events with the presence or absence of a photon during the Ps\nformation.",
        "positive": "Dielectric response of BaTiO3 electronic states under AC fields via\n  microsecond time-resolved X-ray absorption spectroscopy: For the first time, the dielectric response of a BaTiO3 thin film under an AC\nelectric field is investigated using time-resolved X-ray absorption\nspectroscopy at the Ti K-edge to clarify correlated contributions of each\nconstituent atom on the electronic states. Intensities of the pre-edge eg peak\nand shoulder structure just below the main edge increase with an increase in\nthe amplitude of the applied electric field, whereas that of the main peak\ndecreases in an opposite manner. Based on the multiple scattering theory, the\nincrease and decrease of the eg and main peaks are simulated for different Ti\noff-center displacements. Our results indicate that these spectral features\nreflect the inter- and intra-atomic hybridization of Ti 3d with O 2p and Ti 4p,\nrespectively. In contrast, the shoulder structure is not affected by changes in\nthe Ti off-center displacement but is susceptible to the effect of the corner\nsite Ba ions. This is the first experimental verification of the dynamic\nelectronic contribution of Ba to polarization reversal."
    },
    {
        "anchor": "A lithium-ion battery based on a graphene nanoflakes ink anode and a\n  lithium iron phosphate cathode: Li-ion rechargeable batteries have enabled the wireless revolution\ntransforming global communication. Future challenges, however, demands\ndistributed energy supply at a level that is not feasible with the current\nenergy-storage technology. New materials, capable of providing higher energy\ndensity are needed. Here we report a new class of lithium-ion batteries based\non a graphene ink anode and a lithium iron phosphate cathode. By carefully\nbalancing the cell composition and suppressing the initial irreversible\ncapacity of the anode, we demonstrate an optimal battery performance in terms\nof specific capacity, i.e. 165 mAhg-1, estimated energy density of about 190\nWhkg-1 and life, with a stable operation for over 80 charge-discharge cycles.\nWe link these unique properties to the graphene nanoflake anode displaying\ncrystalline order and high uptake of lithium at the edges, as well as to its\nstructural and morphological optimization in relation to the overall battery\ncomposition. Our approach, compatible with any printing technologies, is cheap\nand scalable and opens up new opportunities for the development of\nhigh-capacity Li-ion batteries.",
        "positive": "Local polarization in oxygen-deficient LaMnO$_3$ induced by charge\n  localization in the Jahn-Teller distorted structure: The functional properties of transition metal perovskite oxides are known to\nresult from a complex interplay of magnetism, polarization, strain, and\nstoichiometry. Here, we show that for materials with a cooperative Jahn-Teller\ndistortion, such as LaMnO$_3$ (LMO), the orbital order can also couple to the\ndefect chemistry and induce novel material properties. At low temperatures, LMO\nexhibits a strong Jahn-Teller distortion that splits the $e_g$ orbitals of the\nhigh-spin Mn$^{3+}$ ions and leads to alternating long, short, and intermediate\nMn--O bonds. Our DFT+$U$ calculations show that, as a result of this orbital\norder, the charge localization in LMO upon oxygen vacancy formation differs\nfrom other manganites, like SrMnO$_3$, where the two extra electrons reduce the\ntwo Mn sites adjacent to the vacancy. In LMO, relaxations around the defect\ndepend on which type of Mn--O bond is broken, affecting the $d$-orbital\nenergies and leading to asymmetric and hence polar excess-electron localization\nwith respect to the vacancy. Moreover, we show that the Mn--O bond lengths,\norbital order and consequently the charge localization and polarity are tunable\nvia strain."
    },
    {
        "anchor": "Crystalline Surface Phases of the Liquid Au-Si Eutectic Alloy: A two dimensional crystalline layer is found at the surface of the liquid\neutectic Au$_{82}$Si$_{18}$ alloy above its melting point $T_M=359 ^{\\circ}$C.\nUnderlying this crystalline layer we find a layered structure, 6-7 atomic\nlayers thick. This surface layer undergoes a first-order solid-solid phase\ntransition occurring at $371 ^{\\circ}$C. The crystalline phase observed for\nT$>$371 $^{\\circ}$C is stable up to at least 430 $^{\\circ}$C. Grazing Incidence\nX-ray Diffraction data at T$>$371 $^{\\circ}$C imply lateral order comprising\ntwo coexisting phases of different oblique unit cells, in stark contrast with\nthe single phase with a rectangular unit cell found for low-temperature\ncrystalline phase $359 ^{\\circ}$C$<T<371 ^{\\circ}$C.",
        "positive": "Organic Topological Insulators in Organometallic Lattices: Topological insulators (TIs) are a recently discovered class of materials\nhaving insulating bulk electronic states but conducting boundary states\ndistinguished by nontrivial topology. So far, several generations of TIs have\nbeen theoretically predicted and experimentally confirmed, all based on\ninorganic materials. Here, based on first-principles calculations, we predict a\nfamily of two-dimensional organic TIs made of organometallic lattices. Designed\nby assembling molecular building blocks of triphenyl-metal compounds with\nstrong spin-orbit coupling into a hexagonal lattice, this new classes of\norganic TIs are shown to exhibit nontrivial topological edge states that are\nrobust against significant lattice strain. We envision that organic TIs will\ngreatly broaden the scientific and technological impact of TIs."
    },
    {
        "anchor": "Hydrogenation kinetics of metal hydride catalytic layers: Catalyzing capping layers on top of metal hydrides are often employed to\nenhance the hydrogenation kinetics of metal-hydride based systems such as\nhydrogen sensors. Here, we experimentally study the hydrogenation kinetics of\ncapping layers composed of several alloys of Pd and Au as well as Pt, Ni and\nRu, all with and without an additional PTFE protection layer using a novel\nmethod and under the same set of experimental conditions. Our results\ndemonstrate that doping Pd with Au results in significantly faster\nhydrogenation kinetics, with response times up to five times shorter than Pd\nthrough enhanced diffusion and a reduction of the activation energy. The\nkinetics of non-Pd based materials turns out to be significantly slower and\nmainly limited by the diffusion through the capping layer itself. Surprisingly,\nthe additional PTFE layer was only found to improve the kinetics of Pd-based\ncapping materials and has no significant effect on the kinetics of Pt, Ni and\nRu. Taken together, the experimental results aid in rationally choosing a\nsuitable capping material for the application of metal hydrides and other\nmaterials in a green economy. In addition, the developed method can be used to\nsimultaneously study the hydrogenation kinetics and determine diffusion\nconstants in thin film materials for a wide set of experimental conditions.",
        "positive": "On the thermal and mechanical properties of\n  Mg$_{0.2}$Co$_{0.2}$Ni$_{0.2}$Cu$_{0.2}$Zn$_{0.2}$O across the high-entropy\n  to entropy-stabilized transition: As various property studies continue to emerge on high entropy and\nentropy-stabilized ceramics, we seek further understanding of property changes\nacross the phase boundary between \\enquote{high-entropy} and\n\\enquote{entropy-stabilized}. The thermal and mechanical properties of bulk\nceramic entropy stabilized oxide composition\nMg$_{0.2}$Co$_{0.2}$Ni$_{0.2}$Cu$_{0.2}$Zn$_{0.2}$O are investigated across\nthis critical transition temperature via the transient plane-source method,\ntemperature-dependent X-ray diffraction, and nano-indentation. Thermal\nconductivity remains constant within uncertainty across the multi-to-single\nphase transition at a value of ~2.5 W/mK, while the linear coefficient of\nthermal expansion increases nearly 24 % from 10.8 to 14.1 x 10$^{-6}$ K$^{-1}$.\nMechanical softening is also observed across the transition."
    },
    {
        "anchor": "Surface conductivity of DR1-functionalized organic-inorganic sol-gel\n  materials: In recent years, in looking for an important photorefractive application,\nseveral studies on electro-optic and photoconductive sol-gel responses have\nbeen done. A very important effort has been addressed to establish the\nappropriate induced-orientation procedure, in order to get the highest\nelectro-optic coefficient. In this way a very high coefficient of 48 pm/V at\n831 nm in sol-gel has been already found. Similarly, the importance of the\nnon-linear chromophore concentration into the material electro-optic behavior\nhas been studied. However, the influence of the orientation procedure and the\nchromophore concentration over the photoconductive response has not been\nperformed. In this work we study the vacuum-surface-charge-transport under and\nwithout illumination after poling times of 10, 30 and 120 min on\nDR1-functionalized sol-gel thin films of 1.3 um in thickness with a suitable\nconcentration of DR1. We include the measures before poling for other\nchromophore concentrations. We found the largest density of photocurrent at 633\nnm for a poling time of 30 min. We also measured the order parameter in order\nto follow the Corona induced orientation evolution as function of time for each\ncase. The saturation found into this parameter and into the photoconduction\nshow the existence of an optimal poling time.",
        "positive": "Comment on Quantum paraelectric glass state in SrCu3Ti4O12 [Appl. Phys.\n  Lett.104, 262905 (2014)]: Recently, Kumar et al. [APL 104, 262905 (2014)] have reported quantum\nparaelectric glass state in SrCu3Ti4O12. Their analysis is based on the\nmisconception about the effect of quantum fluctuations on paraelectric\nproperties. There are very serious issues with their analysis of permittivity\nvs T data where authors tried to prove the presence of quantum paraelectricity\nin SrCu3Ti4O12. In the comment we have clearly affirm that the analysis\npresented by the authors do not prove the presence of quantum paraelectric\nbehavior and there by the quantum paraelectric glass state. The quantum\nfluctuations and the frequency dependence of permittivity, showing relaxor like\nbehavior cannot exist simultaneously."
    },
    {
        "anchor": "Magnetic glasses and structural glasses: devitrification and a reentrant\n  transition under CHUF protocol: A recent paper from Raveau's group asserts that the specially designed CHUF\nmeasurement protocol serves to bring out a special feature of the magnetic\nglass state. This protocol, enunciated and applied in our publications since\nover three years, allows establishing phase coexistence through macroscopic\nmeasurements and distinguishing the metastable and stable phases (amongst the\ncoexisting phase fractions across a first order magnetic transition) of a\nglass-like arrested state. In view of the recent report of the vitrification of\nmonoatomic germanium under pressure, we discuss the applicability of an\nanalogous CHUP protocol for states across an arrested first order structural\ntransition, and specifically in establishing whether the vitrification was\npartial or complete.",
        "positive": "Diffusion based degradation mechanisms in giant magnetoresistive spin\n  valves: Spin valve systems based on the giant magnetoresistive (GMR) effect as used\nfor example in hard disks and automotive applications consist of several\nfunctional metallic thin film layers. We have identified by secondary ion mass\nspectrometry (SIMS) two main degradation mechanisms: One is related to oxygen\ndiffusion through a protective cap layer, and the other one is interdiffusion\ndirectly at the functional layers of the GMR stack. By choosing a suitable\nmaterial as cap layer (TaN), the oxidation effect can be suppressed."
    },
    {
        "anchor": "Soliton-like magnetic domain wall motion induced by the interfacial\n  Dzyaloshinskii-Moriya interaction: Topological defects such as magnetic solitons, vortices, Bloch lines, and\nskyrmions have started to play an important role in modern magnetism because of\ntheir extraordinary stability, which can be exploited in the production of\nmemory devices. Recently, a novel type of antisymmetric exchange interaction,\nnamely the Dzyaloshinskii-Moriya interaction (DMI), has been uncovered and\nfound to influence the formation of topological defects. Exploring how the DMI\naffects the dynamics of topological defects is therefore an important task.\nHere we investigate the dynamic domain wall (DW) under a strong DMI and find\nthat the DMI induces an annihilation of topological vertical Bloch lines (VBLs)\nby lifting the four-fold degeneracy of the VBL. As a result, velocity reduction\noriginating from the Walker breakdown is completely suppressed, leading to a\nsoliton-like constant velocity of the DW. Furthermore, the strength of the DMI,\nwhich is the key factor for soliton-like DW motion, can be quantified without\nany side effects possibly arising from current-induced torques or extrinsic\npinnings in magnetic films. Our results therefore shed light on the physics of\ndynamic topological defects, which paves the way for future work in\ntopology-based memory applications.",
        "positive": "Microstructure reconstruction via artificial neural networks: A\n  combination of causal and non-causal approach: We investigate the applicability of artificial neural networks (ANNs) in\nreconstructing a sample image of a sponge-like microstructure. We propose to\nreconstruct the image by predicting the phase of the current pixel based on its\ncausal neighbourhood, and subsequently, use a non-causal ANN model to smooth\nout the reconstructed image as a form of post-processing. We also consider the\nimpacts of different configurations of the ANN model (e.g. number of densely\nconnected layers, number of neurons in each layer, the size of both the causal\nand non-causal neighbourhood) on the models' predictive abilities quantified by\nthe discrepancy between the spatial statistics of the reference and the\nreconstructed sample."
    },
    {
        "anchor": "Exploration of a new reconstructed structure on GaN(0001) surface by\n  Bayesian optimization: GaN(0001) surfaces with Ga- and H-adsorbates are fundamental stages for\nepitaxial growth of semiconductor thin films. We explore stable surface\nstructures with nanometer scale by the density-functional calculations combined\nwith Bayesian optimization, and succeed to reach a single structure with\nsatisfactorily low mixing enthalpy among hundreds of thousand possible\ncandidate structures. We find that the obtained structure is free from any\npostulated high symmetry previously introduced by human intuition, satisfies\nelectron counting rule locally, and shows new adsorbate arrangement, reflecting\ncharacteristics of nitride semiconductors.",
        "positive": "Path Integral Monte Carlo and Density Functional Molecular Dynamics\n  Simulations of Warm, Dense MgSiO$_3$: In order to provide a comprehensive theoretical description of MgSiO$_3$ at\nextreme conditions, we combine results from path integral Monte Carlo (PIMC)\nand density functional molecular dynamics simulations (DFT-MD) and generate a\nconsistent equation of state for this material. We consider a wide range of\ntemperature and density conditions from 10$^4$ to 10$^8$ K and from 0.321 to\n64.2 g$\\,$cm$^{-3}$ (0.1- to 20-fold the ambient density). We study how the L\nand K shell electrons are ionized with increasing temperature and pressure. We\nderive the shock Hugoniot curve and compare with experimental results. Our\nHugoniot curve is in good agreement with the experiments, and we predict a\nbroad compression maximum that is dominated by the K shell ionization of all\nthree nuclei while the peak compression ratio of 4.70 is obtained when the Si\nand Mg nuclei are ionized. Finally we analyze the heat capacity and structural\nproperties of the liquid."
    },
    {
        "anchor": "Damage-cluster distributions and size effect on strength in compressive\n  failure: We investigate compressive failure of heterogeneous materials on the basis of\na continuous progressive damage model. The model explicitely accounts for\ntensile and shear local damage and reproduces the main features of compressive\nfailure of brittle materials like rocks or ice. We show that the size\ndistribution of damage-clusters, as well as the evolution of an order\nparameter, the size of the largest damage-cluster, argue for a critical\ninterpretation of fracture. The compressive failure strength follows a normal\ndistribution with a very small size effect on the mean strength, in good\nagreement with experiments.",
        "positive": "Diffusion and Interdiffusion in Binary Metallic Melts: We discuss the dependence of self- and interdiffusion coefficients on\ntemperature and composition for two prototypical binary metallic melts, Al-Ni\nand Zr-Ni, in molecular-dynamics (MD) computer simulations and the\nmode-coupling theory of the glass transition (MCT). Dynamical processes that\nare mainly entropic in origin slow down mass transport (as expressed through\nself diffusion) in the mixture as compared to the ideal-mixing contribution.\nInterdiffusion of chemical species is a competition of slow kinetic modes with\na strong thermodynamic driving force that is caused by non-entropic\ninteractions. The combination of both dynamic and thermodynamic effects causes\nqualitative differences in the concentration dependence of self-diffusion and\ninterdiffusion coefficients. At high temperatures, the thermodynamic\nenhancement of interdiffusion prevails, while at low temperatures, kinetic\neffects dominate the concentration dependence, rationalized within MCT as the\napproach to its ideal-glass transition temperature $T_c$. The Darken equation\nrelating self- and interdiffusion qualitatively reproduces the\nconcentration-dependence in both Zr-Ni and Al-Ni, but quantitatively, the\nkinetic contributions to interdiffusion can be slower than the lower bound\nsuggested by the Darken equation. As temperature is decreased, the agreement\nwith Darken's equation improves, due to a strong coupling of all kinetic modes\nthat is a generic feature predicted by MCT."
    },
    {
        "anchor": "Stability and energetics of 2D surface crystals in liquid AuSi thin\n  films and nanoscale droplets: Segregation at surfaces of metal-covalent binary liquids is often\nnon-classical and in extreme cases such as AuSi, the surface crystallizes above\nthe melting point. In this study, we employ atomic-scale computational\nframeworks to study the surface crystallization of AuSi films and droplets as a\nfunction of composition, temperature and size. For temperatures in the range\n$T_s^\\ast=765-780$K above the melting point $(T_s^\\ast\\approx1.3\\,T_m)$, both\nthin film and droplet surfaces undergo a first order transition, from a 2D\nAu$_2$Si crystalline phase to a laterally disordered yet stratified layer. The\nthin film surfaces exhibit an effective surface tension that increases with\ntemperature and decreases with Si concentration. On the other hand, for\ndroplets in the size range $10-30$ nm, the bulk Laplace pressure alters the\nsurface segregation as it occurs with respect to a strained bulk. Above\n$T_s^\\ast$ the size effect on the surface tension is small, while for\n$T<T_s^\\ast$ the surface layer is strained and composed of 2D crystallites\nseparated by extended grain boundary scars that lead to large fluctuations in\nits energetics. As a specific application, all-atom simulations of AuSi\ndroplets on Si(111) substrate subject to Si surface flux show that the\nsupersaturation dependent surface tension destabilizes the contact line via\nformation of a precursor wetting film on the solid-vapor interface, and has\nramifications for size selection during VLS-based routes for nanowire growth.\nOur study sheds light on the interplay between stability and energetics of\nsurfaces in these unique class of binary alloys and offers pathways for\nexploiting their surface structure for varied applications such as catalytic\nnanocrystal growth, dealloying, and polymer crystallization.",
        "positive": "Synthesis, Crystal Structure and Properties of a Perovskite-Related\n  Bismuth Phase, (NH4)3Bi2I9: Organic-inorganic halide perovskites, especially methylammonium lead halide,\nhave recently led to a remarkable breakthrough in photovoltaic devices.\nHowever, due to the environmental and stability concerns of the heavy metal,\nlead, in these perovskite based solar cells, research in the non-lead\nperovskite structures have been attracting increasing attention. In this study,\na layered perovskite-like architecture, (NH4)3Bi2I9, was prepared in solution\nand the structure was solved by single crystal X-ray diffraction. The results\nfrom DFT calculations showed the significant lone pair effect of the bismuth\nion and the band gap was measured as around 2.04 eV, which is lower than the\nband gap of CH3NH3PbBr3. Conductivity measurement was also performed to examine\nthe potential in the applications as an alternative to the lead containing\nperovskites."
    },
    {
        "anchor": "Direct Measurement of Periodic Electric Forces in Liquids: The electric forces acting on an atomic force microscope tip in solution have\nbeen measured using a microelectrochemical cell formed by two periodically\nbiased electrodes. The forces were measured as a function of lift height and\nbias amplitude and frequency, providing insight into electrostatic interactions\nin liquids. Real-space mapping of the vertical and lateral components of\nelectrostatic forces acting on the tip from the deflection and torsion of the\ncantilever is demonstrated. This method enables direct probing of electrostatic\nand convective forces involved in electrophoretic and dielectroforetic\nself-assembly and electrical tweezer operation in liquid environments.",
        "positive": "Phase formation characteristics and magnetic properties of bulk Ni2MnGe\n  Heusler alloy: We have systemically studied the effects of annealing temperature and alloy\ncomposition on the structural and magnetic properties of bulk Ni$_{2}$MnGe and\nNi$_{2.1}$Mn$_{0.9}$Ge Heusler alloys. We have observed that both annealing\ntemperature and the alloy composition drastically alter the phases found in the\nsamples due to the presence of competing ternary phases. Annealing at 900 and\n950 $^{\\circ}$C for both alloy compositions facilitate the formation of\nL2$_{1}$ Heusler phase. Nevertheless, formation of Ni$_{5}$Mn$_{4}$Ge$_{3}$ and\nNi$_{16}$Mn$_{6}$Ge$_{7}$ phases cannot be prevented for Ni$_{2}$MnGe and\nNi$_{2.1}$Mn$_{0.9}$Ge alloys, respectively. In order to estimate the magnetic\ncontribution of the Ni$_{5}$Mn$_{4}$Ge$_{3}$ impurity phase to that of the\nparent Ni$_{2}$MnGe, we have also synthesized pure Ni$_{5}$Mn$_{4}$Ge$_{3}$\nalloy. Antiferromagnetic nature of Ni$_{5}$Mn$_{4}$Ge$_{3}$ with low\nmagnetization response allows us to reveal the magnetic response of the\nstoichiometric bulk Ni$_{2}$MnGe. Bulk Ni$_{2}$MnGe shows simple ferromagnetic\nbehavior with a Curie temperature of 300 K, in agreement with the previous\nresults on thin films. Despite the divergence of magnetization curves between\nfield cooled (FC) and field heated (FH) modes, stoichiometric Ni$_{2}$MnGe\nalloy does not undergo a martensitic phase transition based on our variable\ntemperature x-ray diffraction experiments."
    },
    {
        "anchor": "Soft mechanical metamaterials with transformable topology protected by\n  stress caching: Maxwell lattice metamaterials possess a rich phase space with distinct\ntopological states featuring mechanically polarized edge behaviors and strongly\nasymmetric acoustic responses. Until now, demonstrations of non-trivial\ntopological behaviors from Maxwell lattices have been limited to either\nmonoliths with locked configurations or reconfigurable mechanical linkages.\nThis work introduces a transformable topological mechanical metamaterial (TTMM)\nmade from a shape memory polymer and based on a generalized kagome lattice. It\nis capable of reversibly exploring topologically distinct phases of the\nnon-trivial phase space via a kinematic strategy that converts sparse\nmechanical inputs at free edge pairs into a biaxial, global transformation that\nswitches its topological state. Thanks to the shape memory effect, all\nconfigurations are stable even in the absence of confinement or a continuous\nmechanical input. Topologically-protected mechanical behaviors, while robust\nagainst structural (with broken hinges) or conformational defects (up to ~55%\nmis-rotations), are shown to be vulnerable to the adverse effects of stored\nelastic energy from prior transformations (up to a ~70% reduction in edge\nstiffness ratios, depending on hinge width). Interestingly, we show that shape\nmemory polymer's intrinsic phase transitions that modulate chain mobility can\neffectively shield a dynamic metamaterial's topological response (with a 100%\nrecovery) from its own kinematic stress history, an effect we refer to as\n\"stress caching\".",
        "positive": "Co-existence of Topological Non-trivial and Spin Gapless Semiconducting\n  Behavior in MnPO$_4$: A Composite Quantum Compound: Composite quantum compounds (CQC) are classic example of quantum materials\nwhich host more than one apparently distinct quantum phenomenon in physics.\nMagnetism, topological superconductivity, Rashba physics etc. are few such\nquantum phenomenon which are ubiquitously observed in several functional\nmaterials and can co-exist in CQCs. In this letter, we use {\\it ab-initio}\ncalculations to predict the co-existence of two incompatible phenomena, namely\ntopologically non-trivial Weyl semimetal and spin gapless semiconducting (SGS)\nbehavior, in a single crystalline system. SGS belong to a special class of\nspintronics material which exhibit a unique band structure involving a\nsemiconducting state for one spin channel and a gapless state for the other. We\nreport such a SGS behavior in conjunction with the topologically non-trivial\nmulti-Weyl Fermions in MnPO$_4$. Interestingly, these Weyl nodes are located\nvery close to the Fermi level with the minimal trivial band density. A drumhead\nlike surface state originating from a nodal loop around Y-point in the\nBrillouin zone is observed. A large value of the simulated anomalous Hall\nconductivity (1265 $\\Omega^{-1} cm^{-1}$) indirectly reflects the topological\nnon-trivial behavior of this compound. Such co-existent quantum phenomena are\nnot common in condensed matter systems and hence it opens up a fertile ground\nto explore and achieve newer functional materials."
    },
    {
        "anchor": "Molecular Simulation of a Zn-Triazamacrocyle Metal-Organic Frameworks\n  Family with Extraframework Anions: We report an investigation by means of adsorption experiments and molecular\nsimulation of the behavior of a recently synthesized cationic metal-organic\nframework. We used a combination of quantum chemistry calculations and\nclassical forcefield-based Grand Canonical Monte Carlo simulations to shed\nlight onto the localization of extra-framework halogenide anions in the\nmaterial. We also studied the adsorption of small gas molecules into the pores\nof the material using molecular simulation and investigated the coadsorption of\nbinary gas mixtures.",
        "positive": "Weakly nonlocal irreversible thermodynamics: Weakly nonlocal thermodynamic theories are critically revisited. A\nrelocalized, irreversible thermodynamic theory of nonlocal phenomena is given,\nbased on a modified form of the entropy current and new kind of internal\nvariables, the so called current multipliers. The treatment is restricted to\ndeal with nonlocality connected to dynamic thermodynamic variables. Several\nclassical equations are derived, including Guyer-Krumhansl, Ginzburg-Landau and\nCahn-Hilliard type equations."
    },
    {
        "anchor": "A Dramatically Growing Shear Rigidity Length Scale in a Supercooled\n  Glass Former ($NiZr_2$): Finding a suitably growing length scale that increases in tandem with the\nimmense viscous slowdown of supercooled liquids is an open problem associated\nwith the glass transition. Here, we define and demonstrate the existence of one\nsuch length scale which may be experimentally verifiable. This is the length\nscale over which external shear perturbations appreciably penetrate into a\nliquid as the glass transition is approached. We provide simulation based\nevidence of its existence, and its growth by at least an order of magnitude, by\nusing molecular dynamics simulations of NiZr2, a good fragile glass former. On\nthe probed timescale, upon approaching the glass transition temperature from\nabove, this length scale, {\\xi} is also shown to be consistent with Ising-like\nscaling. Furthermore, we demonstrate the possible scaling of {\\xi} about the\ntemperature at which super-Arrhenius growth of viscosity, and a marked growth\nof the penetration depth sets in. Our simulation results suggest that upon\nsupercooling, marked initial increase of the shear penetration depth in fluids\nmay occur in tandem with the breakdown of the Stokes-Einstein relation.",
        "positive": "Structural and Optoelectronic Properties of Thin Film LaWN$_3$: Nitride perovskites are an emerging class of materials that have been\npredicted to display a range of interesting physics and functional properties,\nbut they are under-explored due to the difficulty of synthesizing oxygen-free\nnitrides. LaWN3, recently reported as the first oxygen-free nitride perovskite,\nexhibited polar symmetry and a large piezoelectric coefficient. However, the\npredicted ferroelectric switching was hindered by large leakage current, which\nmotivates better understanding of its electronic structure and optical\nproperties. Here, we study the structure and optoelectronic properties of thin\nfilm LaWN3 in greater detail, employing combinatorial techniques to correlate\nthese properties with cation stoichiometry. We report a two-step synthesis that\nutilizes a more common RF substrate bias instead of a nitrogen plasma source,\nyielding nanocrystalline films that are crystallized by ex-situ annealing. We\ninvestigate the structure and composition of these films, finding\npolycrystalline La-rich and highly textured W-rich films. The optical\nabsorption onset and temperature- and magnetic field-dependent resistivity are\nconsistent with semiconducting behavior and are highly sensitive to cation\nstoichiometry, which may be related to amorphous impurities: metallic W or WNx\nin W-rich samples and insulating La2O3 in La-rich samples. The fractional\nmagnetoresistance is linear and small, consistent with defect scattering, and a\nW-rich sample has n-type carriers with high densities and low mobilities. We\ndemonstrate a photoresponse in LaWN3: the resistivity of a La-rich sample is\nenhanced by 28% at low temperature, likely due to a defect trapping mechanism.\nThe physical properties of LaWN3 are highly sensitive to cation stoichiometry,\nlike many oxide perovskites, which therefore calls for precise composition\ncontrol to utilize the interesting properties observed in this nitride\nperovskite."
    },
    {
        "anchor": "Defect energetics and electronic structures of As-doped p-type ZnO\n  crystals: A first-principles study: First-principles calculations based on density functional theory have been\ncarried out to understand the mechanism of fabricating As-doped p-type ZnO\nsemiconductors. It has been confirmed that AsZn-2VZn complex is the most\nplausible acceptor among several candidates for p-type doping by computing the\nformation and ionization energies. The electronic band structures and\natomic-projected density of states of AsZn-2VZn defect complex-contained ZnO\nbulks have been computed. The acceptor level in AsZn-2VZn band structure has\nfound to be 0.12 eV, which is in good agreement with the experimental\nionization energy (0.12 ~ 0.18 eV). The hybridization among O 2p, Zn 3d and As\n4s states has been observed around the valence band maximum.",
        "positive": "Excitons and Many-Electron Effects in the Optical Response of\n  Single-Walled Boron Nitride Nanotubes: We report first-principles calculations of the effects of quasiparticle\nself-energy and electron-hole interaction on the optical properties of\nsingle-walled BN nanotubes. Excitonic effects are shown to be even more\nimportant in BN nanotubes than in carbon nanotubes. Electron-hole interactions\ngive rise to complexes of bright (and dark) excitons, which qualitatively alter\nthe optical response. Excitons with binding energy larger than 2 eV are found\nin the (8,0) BN nanotubes. Moreover, unlike the carbon nanotubes, theory\npredicts that these exciton states are comprised of coherent supposition of\ntransitions from several different subband pairs, giving rise to novel\nbehaviors."
    },
    {
        "anchor": "Real-space charge distribution of the cobalt ion and its relation with\n  charge and spin states: The charge state of an ion provides a simplified electronic picture of the\nbonding in compounds, and heuristically explains the basic electronic structure\nof a system. Despite its usefulness, the physical and chemical definition of a\ncharge state is not a trivial one, and the essential idea of electron transfer\nis found to be not a realistic explanation. Here, we study the real-space\ncharge distribution of a cobalt ion in its various charge and spin states, and\nexamine the relation between the formal charge/spin states and the static\ncharge distribution. Taking the prototypical cobalt oxides, La/SrCoO$_3$, and\nbulk Co metal, we confirm that no prominent static charge transfer exists for\ndifferent charge states. However, we show that small variations exist in the\nintegrated charges for different charge states, and these are compared to the\nvarious spin state cases.",
        "positive": "Dynamic atomic reconstruction: how Fe3O4 thin films evade polar\n  catastrophe for epitaxy: Polar catastrophe at the interface of oxide materials with strongly\ncorrelated electrons has triggered a flurry of new research activities. The\nexpectations are that the design of such advanced interfaces will become a\npowerful route to engineer devices with novel functionalities. Here we\ninvestigate the initial stages of growth and the electronic structure of the\nspintronic Fe3O4/MgO (001) interface. Using soft x-ray absorption spectroscopy\nwe have discovered that the so-called A-sites are completely missing in the\nfirst Fe3O4 monolayer. This allows us to develop an unexpected but elegant\ngrowth principle in which during deposition the Fe atoms are constantly on the\nmove to solve the divergent electrostatic potential problem, thereby ensuring\nepitaxy and stoichiometry at the same time. This growth principle provides a\nnew perspective for the design of interfaces."
    },
    {
        "anchor": "Plasmonic crystals for ultrafast nanophotonics: Optical switching of\n  surface plasmon polaritons: We demonstrate that the dispersion of surface plasmon polaritons in a\nperiodically perforated gold film can be efficiently manipulated by femtosecond\nlaser pulses with the wavelengths far from the intrinsic resonances of gold.\nUsing a time- and frequency- resolved pump-probe technique we observe shifting\nof the plasmon polariton resonances with response times from 200 to 800 fs\ndepending on the probe photon energy, through which we obtain comprehensive\ninsight into the electron dynamics in gold. We show that Wood anomalies in the\noptical spectra provide pronounced resonances in differential transmission and\nreflection with magnitudes up to 3% for moderate pump fluences of 0.5 mJ/cm^2.",
        "positive": "Sequence Engineering of Copolymers using Evolutionary Computing: The correlations between the sequence of monomers in a polymer and its\nthree-dimensional structure is a grand challenge in polymer science and\nbiology. The properties and functions of macromolecules depend on their 3D\nshape that has appeared to be dictated by their monomer sequence. However, the\nprogress towards understanding the sequence-structure-property correlations and\ntheir utilization in materials engineering are slow because it is almost\nimpossible to characterize astronomically large number of possible sequences of\na copolymer using traditional experimental and simulation methods. To address\nthis problem, here, we combine evolutionary computing and coarse-grained\nmolecular dynamics simulation and study the sequence-structure correlations of\na model AB type copolymer system. The CGMD based evolutionary algorithm screens\nthe sequence space of the copolymer efficiently and identifies wide range of\nsingle molecule structures including extremal radius of gyrations. The data\nprovide new insights on the sequence-Rg correlations of the copolymer system\nand their impact on the structure and functionality of polymeric materials. The\nwork highlights the opportunities of sequence specific control of\nmacromolecular structure for designing materials with exceptional properties."
    },
    {
        "anchor": "Influence of complex disorder on skew-scattering Hall effects in\n  $L1_0$-ordered FePt alloy: We show by first-principles calculations that the skew-scattering anomalous\nHall and spin-Hall angles of L$1_0$-ordered FePt drastically depend on\ndifferent types of disorder. A different sign of the AHE is obtained when\nslightly deviating from the stoichiometric ratio towards the Fe-rich side as\ncompared to the Pt-rich side. For stoichiometric samples, short-range ordering\nof defects has a profound effect on the Hall angles and can change them by a\nfactor of $2$ as compared to the case of uncorrelated disorder. This might\nexplain the vast range of anomalous Hall angles measured in experiments, which\nundergo different preparation procedures and thus might differ in their\ncrystallographic quality.",
        "positive": "Correlation between anion defects and ion beam induced luminescence in\n  Y4Zr3O12: Potential applications of Zr/Al ODS alloys vests on the irradiation stability\nof the Y4Zr3O12 dispersoids. Fundamental studies to identify the type of\ndefects are important in order to recognize pathways for damage alleviation. In\nthis context, studies relating to identification of point defects and their\nclusters by in-situ ionoluminescence spectroscopy were taken up. The\nionoluminescence spectrum acquired during 100 keV He+ ion irradiation shows two\nprominent bands, at 330 nm and 415 nm. Using density functional theory\ncalculations with HSE06 hybrid exchange correlation functional, the luminescent\nbands have been identified to be arising due to native and irradiation induced\noxygen vacancy defects in charged and neutral configurations."
    },
    {
        "anchor": "Self-organization of current channels percolation in polymer composite\n  films with thermal nonlinearity of conductivity: comparison of experimental\n  data and computer simulations: Numerical methods are developed to solve the problem of abnormal changes of\ncurrent (conductivity) in polymer composite films which may be used as current,\npressure or temperature sensors. General nonlinear model includes the heat\nequation, the nonlinear dependence of the resistivity of insulating composite\nintervals on temperature, taking into account the dehydrochlorination reaction,\nthe appearance of conducting systems conjugated double bonds, and Ohm's law for\nfull control circuit net. The property of thermal conductivity equation to\nsmooth surges of source function allows to resolve the nonlinear closed system\nand carry out calculations by successive small time steps. As a result of\nnumerical calculations we succeeded to explain and simulate virtually all\npreviously seemed anomalous phenomena including spontaneous transitions in the\nhighly conductive state, the conductivity jumps with temperature change, the\ndependence on sample thickness, etc.",
        "positive": "First-principles Approaches to Simulate Lithiation in Silicon Electrodes: Silicon is viewed as an excellent electrode material for lithium batteries\ndue to its high lithium storage capacity. Various Si nano-structures, such as\nSi nanowires, have performed well as lithium battery anodes and have opened up\nexciting opportunities for the use of Si in energy storage devices. The\nmechanism of lithium insertion and the interaction between Li and the Si\nelectrode must be understood at the atomic level; this understanding can be\nachieved by first-principles simulation. Here, first-principles computations of\nlithiation in silicon electrodes are reviewed. The review focuses on three\naspects: the various properties of bulk Li-Si compounds with different Li\nconcentrations, the electronic structure of Si nanowires and Li insertion\nbehavior in Si nanowires, and the dynamic lithiation process at the Li/Si\ninterface. Potential study directions in this research field and difficulties\nthat the field still faces are discussed at the end."
    },
    {
        "anchor": "Impedance spectroscopy study on post-annealing-tuned polycrystalline\n  CaCu3Ti4O12 films: Evidence of Barrier Layer Capacitor Effects: In this paper, impedance spectroscopy study was performed to establish the\nelectrical property and microstructure relations of the as-deposited and\npost-annealed polycrystalline CCTO films prepared on Pt/Ti/SiO2/Si (100)\nsubstrates by pulsed-laser deposition (PLD). Our results demonstrated that the\nas-deposited polycrystalline CCTO film was made of insulating grain boundaries\nwith semiconducting grains, indicating that the high-dielectric-constant is\nattributed to the barrier layer capacitor (BLC) effects. The simple\nresistor-capacitor (RC) equivalent circuit and the modified constant phase\nelement (CPE) circuit were used to describe the impedance spectroscopy, and\nexcellent agreement between the calculated and measured curves was obtained in\nthe CPE circuit. The resistance and capacitance of the grains and grain\nboundaries can be tuned by changing the annealing atmosphere and temperature.\nUnder oxygen-absent annealing atmosphere, the electric resistances of the grain\nboundaries changed greatly but the resistance of the grains has almost no\nchange. While under oxygen annealing atmosphere, the reverse happened. On the\nbasis of this result, it is demonstrated that the origin of the\nsemiconductivity of the grains in CCTO polycrystalline films arises from their\noxygen-loss, while the grain boundaries are close to oxygen- stoicheometry.",
        "positive": "Magnetism and electronic structure calculation of SmN: The results of the electronic structure calculations performed on SmN by\nusing the LDA+U method with and without including the spin-orbit coupling are\npresented. Within the LDA+U approach, a N(2$p$) band polarization of $\\simeq\n0.3\\ \\mu_B$ is induced by Sm(4$f$)-N(2$p$) hybridization, and a half-metallic\nground state is obtained. By including spin-orbit coupling the magnetic\nstructure was shown to be antiferromagnetic of type II, with Sm spin and\norbital moments nearly cancelling. This results into a semiconducting ground\nstate, which is in agreement with experimental results."
    },
    {
        "anchor": "Computational identification of Ga-vacancy related electron paramagnetic\n  resonance centers in $\u03b2$-Ga$_2$O$_3$: A combined experimental/theoretical study of the EPR in irradiated\n$\\beta$-Ga$_2$O$_3$ is presented. Four EPR spectra, two $S=1/2$ and two $S=1$,\nare observed after high-energy proton or electron irradiation. One of the S=1/2\nspectra (EPR1) can be observed at room temperature and below and is\ncharacterized by the spin Hamiltonian parameters $g_b=2.0313$, $g_c=2.0079$,\n$g_{a*}=2.0025$ and a quasi isotropic hyperfine interaction with two equivalent\nGa neighbors of $~\\sim$14 G on $^{69}$Ga. The second (EPR2) is observed after\nphotoexcitation (with threshold 2.8 eV) at low temperature and is characterized\nby $g_b=2.0064$, $g_c=2.0464$, $g_{a*}=2.0024$ and a quasi isotropic hyperfine\ninteraction with two equivalent Ga neighbors of 10 G. A spin $S=1$ spectrum\nwith a similar g-tensor and a 50\\% reduced hyperfine splitting accompanies each\nof these, which is indicative of a defect of two weakly coupled $S=1/2$\ncenters. DFT calculations of the magnetic resonance fingerprint of a wide\nvariety of native defect models are carried out to identify these EPR centers\nin terms of specific defect configurations. The EPR1 center is proposed to\ncorrespond to a complex of two tetrahedral $V_\\mathrm{Ga1}$ with an\ninterstitial Ga in between them. This model was previously shown to have lower\nenergy than the simple tetrahedral Ga vacancy and has a $2-/3-$ transition\nlevel higher than other $V_\\mathrm{Ga}$ related models, which would explain why\nthe other ones are already in their diamagnetic $3-$ state and are thus not\nobserved if the Fermi level is pinned approximately at this level. The EPR2\nspectra are proposed to correspond to the octahedral $V_\\mathrm{Ga2}$. Models\nbased on self-trapped holes and oxygen interstitials are ruled out because they\nwould have hyperfine interaction with more than two Ga nuclei and because they\ncan not support a corresponding $S=1$ center.",
        "positive": "Defect-engineered graphene for bulk supercapacitors with high energy and\n  power densities: The development of high-energy and high-power density supercapacitors (SCs)\nis critical for enabling next-generation energy storage applications.\nNanocarbons are excellent SC electrode materials due to their economic\nviability, high-surface area, and high stability. Although nanocarbons have\nhigh theoretical surface area and hence high double layer capacitance, the net\namount of energy stored in nanocarbon-SCs is much below theoretical limits due\nto two inherent bottlenecks: i) their low quantum capacitance and ii) limited\nion-accessible surface area. Here, we demonstrate that defects in graphene\ncould be effectively used to mitigate these bottlenecks by drastically\nincreasing the quantum capacitance and opening new channels to facilitate ion\ndiffusion in otherwise closed interlayer spaces. Our results support the\nemergence of a new energy paradigm in SCs with 250% enhancement in double layer\ncapacitance beyond the theoretical limit. Furthermore, we demonstrate prototype\ndefect engineered bulk SC devices with energy densities 500% higher than\nstate-of-the-art commercial SCs without compromising the power density."
    },
    {
        "anchor": "Organic glasses: cluster structure of the random energy landscape and\n  its effect on charge transport and injection: An appropriate model for the random energy landscape in organic glasses is a\nspatially correlated Gaussian field, generated by randomly located and oriented\ndipoles and quadrupoles. Correlation properties of energetic disorder directly\ndictates the mobility dependence on the applied electric field. Electrostatic\ndisorder is significantly modified in the vicinity of the electrode that\naffects injection properties. Correlated Gaussian field forms clusters. We\nsuggest a simple method to estimate an asymptotics of the cluster distribution\non size for deep clusters where a value of the field on each site is much\ngreater than the rms disorder. Hopping transport in organic glasses in the case\nof high carrier density could be described in terms of the effective\ndensity-dependent temperature.",
        "positive": "Traversal of pulses through negative ($\\varepsilon$, $\u03bc$) materials: We study the traversal times of electromagnetic pulses across dispersive\nmedia with negative dielectric permittivity ($\\varepsilon$) and magnetic\npermeability ($\\mu$) parameters. First we investigate the transport of optical\npulses through an electrical plasma and a negative refractive index medium\n(NRM) of infinite and semi-infinite extents where no resonant effects come into\nplay. The total delay time of the pulse constitutes of the group delay time and\nthe reshaping delay time as analyzed by Peatross et al \\cite{peatross}. For\nevanescent waves, even with broadband width, the total delay time is negative\nfor an infinite medium whereas it is positive for the semi-infinite case.\nEvidence of the Hartman effect is seen for small propagation distance compared\nto the free space pulse length. The reshaping delay mostly dominates the total\ndelay time in NRM whereas it vanishes when $\\varepsilon(\\omega)=\\mu(\\omega)$.\n  Next we present results on the propagation times through a dispersive slab.\nWhile both large bandwidth and large dissipation have similar effects in\nsmoothening out the resonant features that appear due to Fabry-P\\'{e}rot\nresonances, large dissipation can result in very small or even negative\ntraversal times near the resonant frequencies. We investigate the traversal and\nthe Wigner delay times for obliquely incident pulses. The coupling of\nevanescent waves to slab plasmon polariton modes results in large traversal\ntimes at the resonant conditions. We also find that the group velocity mainly\ncontributes to the delay time for pulse propagating across a slab with\nrefractive index (n) = -1. The traversal times are positive and subluminal for\npulses with sufficiently large bandwidths."
    },
    {
        "anchor": "Strain induced magnetic transition in CaMnO$_3$ ultra thin films: The effect of high tensile strain and low dimensionality on the magnetic and\nelectronic properties of CaMnO$_3$ ultrathin films, epitaxially grown on\nSrTiO$_3$ substrates, are experimentally studied and theoretically analyzed. By\nmeans of ab initio calculations, we find that, both, the high strain produced\nby the substrate and the presence of the free surface contribute to the\nstabilization of an in-plane ferromagnetic coupling, giving rise to a non-zero\nnet magnetic moment in the ultrathin films. Coupled with this change in the\nmagnetic order we find an insulator-metal transition triggered by the quantum\nconfinement and the tensile epitaxial strain. Accordingly, our magnetic\nmeasurements in 3nm ultrathin films show a ferromagnetic hysteresis loop,\nabsent in the bulk compound due to its G-type antiferromagnetic structure.",
        "positive": "Equation of state of boron subarsenide B12As2 to 47 GPa: Compressibility of boron subarsenide B12As2 has been studied by synchrotron\nX-ray diffraction up to 47 GPa at room temperature in a diamond anvil cell\nusing Ne pressure transmitting medium. A fit of experimental p-V data by Vinet\nequation of state yielded the bulk modulus of 150(4) GPa and its first pressure\nderivative of 6.4(3). No pressure-induced phase transitions have been observed."
    },
    {
        "anchor": "Probing the local environment of two-dimensional ordered vacancy\n  structures in Ga2SeTe2 via aberration-corrected electron microscopy: There has been considerable interest in chalcogenide alloys with high\nconcentrations of native vacancies that lead to properties desirable for\nthermoelectric and phase-change materials. Recently, vacancy ordering has been\nidentified as the mechanism for metal-insulator transitions observed in\nGeSb2Te4 and an unexpectedly low thermal conductivity in Ga2Te3. Here, we\nreport the direct observation of vacancy ordering in Ga2SeTe2 utilizing\naberration-corrected electron microscopy. Images reveal a cation-anion dumbbell\ninversion associated with the accommodation of vacancy ordering across the\nentire crystal. The result is a striking example of the interplay between\nnative defects and local structure.",
        "positive": "Sharpening surface of magnetic paranematic droplets: In a non-uniform magnetic field, the droplets of colloids of nickel nanorods\nand nanoparticles aggregate to form a cusp at the droplet surface not deforming\nthe entire droplet shape. When the field is removed, nanorods diffuse away and\ncusp disappears. Spherical particles can form cusps in a similar way, but they\nstay aggregated after release of the field; finally, the aggregates settle down\nto the bottom of the drop. X-ray phase contrast imaging reveals that nanorods\nin the cusps stay parallel to each other without visible spatial order of their\ncenters of mass. Formation of cusps can be explained with a model that includes\nmagnetostatic and surface tension forces. The discovered possibility of\ncontrolled assembly and quenching of nanorod orientation under the cusped\nliquid surface offers vast opportunities for alignment of carbon nanotubes,\nnanowires and nanoscrolls, prior to spinning them into superstrong and\nmultifunctional fibers. Magneto and electrostatic analogy suggests that similar\nideal alignment can be achieved with the rod-like dipoles subject to a strong\nelectric filed."
    },
    {
        "anchor": "Ultrafast optical control of magnetization in EuO thin films: All-optical pump-probe detection of magnetization precession has been\nperformed for ferromagnetic EuO thin films at 10 K. We demonstrate that the\ncircularly-polarized light can be used to control the magnetization precession\non an ultrafast time scale. This takes place within the 100 fs duration of a\nsingle laser pulse, through combined contribution from two nonthermal\nphotomagnetic effects, i.e., enhancement of the magnetization and an inverse\nFaraday effect. From the magnetic field dependences of the frequency and the\nGilbert damping parameter, the intrinsic Gilbert damping coefficient is\nevaluated to be {\\alpha} \\approx 3\\times10^-3.",
        "positive": "Tuning Magnetotransport in PdPt/Y3Fe5O12: Effects of magnetic proximity\n  and spin orbital coupling: Anisotropic magnetoresistance (AMR) ratio and anomalous Hall conductivity\n(AHC) in PdPt/Y$_3$Fe$_5$O$_{12}$ (YIG) system are tuned significantly by spin\norbital coupling strength $\\xi$ through varying the Pt concentration. For both\nPt/YIG and Pd/YIG, the maximal AMR ratio is located at temperatures for the\nmaximal susceptibility of paramagnetic Pt and Pd metals. The AHC and ordinary\nHall effect both change the sign with temperature for Pt-rich system and vice\nversa for Pd-rich system. The present results ambiguously evidence the spin\npolarization of Pt and Pd atoms in contact with YIG layers. The global\ncurvature near the Fermi surface is suggested to change with the Pt\nconcentration and temperature."
    },
    {
        "anchor": "C K-edge in polymerized C$_{60}$ : experiment and theory: The paper has been withdrawn",
        "positive": "Electronic and mechanical properties of few-layer borophene: We report first principle calculations of electronic and mechanical\nproperties of few-layer borophene with the inclusion of interlayer van der\nWaals (vdW) interaction. The anisotropic metallic behaviors are preserved from\nmonolayer to few-layer structures. The energy splitting of bilayer borophene at\n$\\Gamma$ point near the Fermi level is about 1.7 eV, much larger than the\nvalues (0.5--1 eV) of other layered semiconductors, indicating much stronger\nvdW interactions in metallic layered borophene. In particular, the critical\nstrains are enhanced by increasing the number of layers, leading to much more\nflexibility than that of monolayer structure. On the one hand, because of the\nbuckled atomic structures, the out-of-plane negative Poisson's ratios are\npreserved as the layer-number increases. On the other hand, we find that the\nin-plane negative Poisson's ratios disappear in layered borophene, which is\nvery different from puckered black phosphorus. The negative Poisson's ratio\nwill recover if we enlarge the interlayer distance to 6.3 $\\mbox\\AA$,\nindicating that the physical origin behind the change of Poisson's ratios is\nthe strong interlayer vdW interactions in layered borophene."
    },
    {
        "anchor": "On the origin and the manipulation of ferromagnetism in Fe$_3$GeTe$_2$:\n  defects and dopings: To understand the magnetic properties of Fe$_3$GeTe$_2$, we performed the\ndetailed first-principles study. Contrary to the conventional wisdom, it is\nunambiguously shown that Fe$_3$GeTe$_2$ is not ferromagnetic but\nantiferromagnetic carrying zero net moment in its stoichiometric phase. Fe\ndefect and hole doping are the keys to make this material ferromagnetic, which\nare shown by the magnetic force response as well as the total energy\ncalculation with the explicit Fe defects and the varied system charges.\nFurther, we found that the electron doping also induces the antiferro- to\nferromagnetic transition. It is a crucial factor to understand the notable\nrecent experiment of gate-controlled ferromagnetism. Our results not only\nunveil the origin of ferromagnetism of this material but also show how it can\nbe manipulated with defect and doping.",
        "positive": "High spin polarization in epitaxial films of ferrimagnetic Mn3Ga: Ferrimagnetic Mn3Ga exhibits a unique combination of low saturation\nmagnetization (Ms = 0.11 MA m-1) and high perpendicular anisotropy with a\nuniaxial anisotropy constant of Ku = 0.89 MJ m-3. Epitaxial c-axis films\nexhibit spin polarization as high as 58%, measured using point contact Andreev\nreflection. These epitaxial films will be able to support thermally stable\nsub-10 nm bits for spin transfer torque memories."
    },
    {
        "anchor": "Protective capping of topological surface states of intrinsically\n  insulating Bi$_2$Te$_3$: We have identified epitaxially grown elemental Te as a capping material that\nis suited to protect the topological surface states of intrinsically insulating\nBi$_2$Te$_3$. By using angle-resolved photoemission, we were able to show that\nthe Te overlayer leaves the dispersive bands of the surface states intact and\nthat it does not alter the chemical potential of the Bi$_2$Te$_3$ thin film.\nFrom in-situ four-point contact measurements, we observed that the conductivity\nof the capped film is still mainly determined by the metallic surface states\nand that the contribution of the capping layer is minor. Moreover, the Te\noverlayer can be annealed away in vacuum to produce a clean Bi$_2$Te$_3$\nsurface in its pristine state even after the exposure of the capped film to\nair. Our findings will facilitate well-defined and reliable ex-situ experiments\non the properties of Bi$_2$Te$_3$ surface states with nontrivial topology.",
        "positive": "Intrinsic Magnetism of Grain Boundaries in Two-dimensional Metal\n  Dichalcogenides: Grain boundaries (GBs) are structural imperfections that typically degrade\nthe performance of materials. Here we show that dislocations and GBs in\ntwo-dimensional (2D) metal dichalcogenides MX2 (M = Mo, W; X = S, Se) can\nactually improve the material by giving it a qualitatively new physical\nproperty: magnetism. The dislocations studied all have a substantial magnetic\nmoment of ~1 Bohr magneton. In contrast, dislocations in other well-studied 2D\nmaterials are typically non-magnetic. GBs composed of pentagon-heptagon pairs\ninteract ferromagnetically and transition from semiconductor to half-metal or\nmetal as a function of tilt angle and/or doping level. When the tilt angle\nexceeds 47{\\deg} the structural energetics favor square-octagon pairs and the\nGB becomes an antiferromagnetic semiconductor. These exceptional magnetic\nproperties arise from an interplay of dislocation-induced localized states,\ndoping, and locally unbalanced stoichiometry. Purposeful engineering of\ntopological GBs may be able to convert MX2 into a promising 2D magnetic\nsemiconductor."
    },
    {
        "anchor": "Complex structures in the Au-Cd alloy system: Hume-Rothery mechanism as\n  origin: The binary (simple metal) phase diagram Au-Cd contains a number of\nintermetallic compounds with various distortions, superlattices and vacancies.\nTo understand the reasons of these structural complexities and their phase\nstability, we analyze these crystal structures within the nearly free-electron\nmodel in the frame of Fermi sphere - Brillouin zone interactions. Examination\nof the Brillouin-Jones configuration in relation to the nearly-free electron\nFermi sphere provides insights for significance of the valence electron energy\ncontribution to the phase stability. Representation of these complex structures\nin the reciprocal space clarifies their relationship to simple basic cells.\nThis approach shows the importance of the additional planes for the stability\nof superslattices. The AuCd-hP18, AuCd3-hP24 and AuCd4-hP273 structures are\nshown to be related to the AuCd-cP2 via rhombohedral distortion with\nsuperlattices and vacancies.",
        "positive": "The effects of interstitials clustering on the configurational entropy\n  of bcc solid solutions: This work presents a simple model for describing the interstitials behavior\nin solid solutions enlarging the current random interstitial atoms paradigm. A\ngeneral and parameter-free analytical expression to compute the configurational\nentropy, valid for any tetrahedral or octahedral interstitial solutions and\nsuitable for the treatment of interstitials clustering, is deduced for that\npurpose. The effect of interstitials clustering on the configurational entropy\nis shown by applying the methodology to the Nb-H and bcc Zr-H solid solutions.\nThe model for Nb-H presented in this work, based on the existence of H pairs in\nthe \\alpha phase and double pairs in the \\alpha 'phase, provides the basis to\nexplain the unsolved controversies in this system. The unusual shape of the\npartial configurational entropy measured in bcc Zr-H can be accurately\ndescribed if a small amount of H clusters are included in the solution."
    },
    {
        "anchor": "A consistent interface element formulation for geometrical and material\n  nonlinearities: Decohesion undergoing large displacements takes place in a wide range of\napplications. In these problems, interface element formulations for large\ndisplacements should be used to accurately deal with coupled material and\ngeometrical nonlinearities. The present work proposes a consistent derivation\nof a new interface element for large deformation analyses. The resulting\ncompact derivation leads to a operational formulation that enables the\naccommodation of any order of kinematic interpolation and constitutive behavior\nof the interface. The derived interface element has been implemented into the\nfinite element codes FEAP and ABAQUS by means of user-defined routines. The\ninterplay between geometrical and material nonlinearities is investigated by\nconsidering two different constitutive models for the interface (tension\ncut-off and polynomial cohesive zone models) and small or finite deformation\nfor the continuum. Numerical examples are proposed to assess the mesh\nindependency of the new interface element and to demonstrate the robustness of\nthe formulation. A comparison with experimental results for peeling confirms\nthe predictive capabilities of the formulation.",
        "positive": "Structural relaxations in electronically excited poly(para-phenylene): Structural relaxations in electronically excited poly(para-phenylene) are\nstudied using many-body perturbation theory and density-functional-theory\nmethods. A sophisticated description of the electron-hole interaction is\nrequired to describe the energies of the excitonic states, but we show that the\nstructural relaxations associated with exciton formation can be obtained quite\naccurately within a constrained density-functional-theory approach. We find\nthat the structural relaxations in the low-energy excitonic states extend over\nabout 8 monomers, leading to an energy reduction of 0.22 eV and a Stokes shift\nof 0.40 eV."
    },
    {
        "anchor": "(Sub)surface mobility of oxygen vacancies at the TiO$_2$ anatase (101)\n  surface: Anatase is a metastable polymorph of TiO$_2$. In contrast to the more\nwidely-studied TiO$_2$ rutile, O vacancies (V$_\\mathrm O$'s) are not stable at\nthe anatase (101) surface. Low-temperature STM shows that surface V$_\\mathrm\nO$'s, created by electron bombardment at 105 K, start migrating to subsurface\nsites at temperatures $\\geq$ 200 K. After an initial decrease of the V$_\\mathrm\nO$ density, a temperature-dependent dynamic equilibrium is established where\nV$_\\mathrm O$'s move to subsurface sites and back again, as seen in time-lapse\nSTM images. We estimate that activation energies for subsurface migration lie\nbetween 0.6 and 1.2 eV; in comparison, DFT calculations predict a barrier of\nca. 0.75 eV. The wide scatter of the experimental values might be attributed to\ninhomogeneously-distributed subsurface defects in the reduced sample.",
        "positive": "Transferring Axial Molecular Chirality Through a Sequence of On-Surface\n  Reactions: Fine management of chiral processes on solid surfaces has progressed over the\nyears, yet still faces the need for the controlled and selective production of\nadvanced chiral materials. Here, we report on the use of enantiomerically\nenriched molecular building blocks to demonstrate the transmission of their\nintrinsic chirality along a sequence of on-surface reactions. Triggered by\nthermal annealing, the on-surface reac-tions induced in this experiment involve\nfirstly the coupling of the chiral reactants into chiral polymers and\nsubsequently their transformation into planar prochiral graphene nanoribbons.\nOur study reveals that the axial chirality of the reactant is not only\ntransferred to the polymers, but also to the planar chirality of the graphene\nnanoribbon end products. Such chirality transfer consequently allows, starting\nfrom ad-equate enantioenriched reactants, for the controlled production of\nchiral and prochiral organic nanoarchi-tectures with pre-defined handedness."
    },
    {
        "anchor": "Antiferromagnetic transitions in `T-like' BiFeO3: Recent studies have reported the existence of an epitaxially-stabilized\ntetragonal-like ('T-like') monoclinic phase in BiFeO3 thin-films with high\nlevels of compressive strain. While their structural and ferroelectric\nproperties are different than those of rhombohedral-like ('R-like') films with\nlower levels of strain, little information exists on magnetic properties. Here,\nwe report a detailed neutron scattering study of a nearly phase-pure film of\nT-like BiFeO3. By tracking the temperature dependence and relative intensity of\nseveral superstructure peaks in the reciprocal lattice cell, we confirm\nantiferromagnetism with largely G-type character and TN = 324 K, significantly\nbelow a structural phase transition at 375 K, contrary to previous reports.\nEvidence for a second transition, possibly a minority magnetic phase with\nC-type character is also reported with TN = 260 K. The co-existence of the two\nmagnetic phases in T-like BiFeO3 and the difference in ordering temperatures\nbetween R-like and T-like systems is explained through simple Fe-O-Fe bond\ndistance considerations.",
        "positive": "Band bending at the interface in Polyethylene-MgO nanocomposite\n  dielectric: Polymer nanocomposite dielectrics are promising materials for electrical\ninsulation in high voltage applications. However, the physics behind their\nperformance is not yet fully understood. We use density functional theory to\ninvestigate electronic properties of the interfacial area in magnesium\noxide-polyethylene nanocomposite. Our results demonstrate polyethylene\nconduction band matching with conduction bands of different surfaces of\nmagnesium oxide. Such band bending results in long range potential wells of up\nto 2.6 eV deep. Furthermore, the fundamental influence of silicon treatment on\nmagnesium oxide surface properties is assessed. We report a reduction of the\nsurface-induced states at the silicon-treated interface. The simulations\nprovide information used to propose a new model for charge trapping in\nnanocomposite dielectrics."
    },
    {
        "anchor": "Carboxyl and Amine Functionalized Carboranethiol SAMs on Au(111) : A\n  Dispersion Corrected Density Functional Theory Study: The morphological and electronic properties of isolated and monolayer phases\nof carboxyl- and amine-functionalized carboranethiols on unreconstructed\nAu(111) were determined using density functional theory calculations by\nincluding van der Waals interactions. The groups are effective in the assembly\nof pristine adlayers on gold and also offer functionality when exposed at the\nSAM-environment interface. Anisotropy brought by both functional groups\nincreases tilting of carboranethiols relative to the surface normal and\nabsolute values of the dissociative chemisorption energies. Positional\nisomerization and the functional groups modify the molecular dipole moments\nwhich influnce the adsorption characteristics. Even though carboxylic acid and\namine groups have different chemical properties, they have similar effects on\nthe adsoprtion characteristics of carboranethiols. Dense packing favors\nintermolecular interactions which gives a stronger binding relative to isolated\nadsorption. The carboranethiols with the functional groups can be arranged in\nthe same lateral direction or in a dimer conformation with molecues facing each\nother. Carboxyl and amine groups offer functionalization of cabranethiol SAMs\nand in conjuction with positional isomerization shift tunability ranges of the\nwork function of gold to higher energies.",
        "positive": "Matching Crystal Structures Atom-to-Atom: Finding an optimal match between two different crystal structures underpins\nmany important materials science problems, including describing solid-solid\nphase transitions, developing models for interface and grain boundary\nstructures. In this work, we formulate the matching of crystals as an\noptimization problem where the goal is to find the alignment and the\natom-to-atom map that minimize a given cost function such as the Euclidean\ndistance between the atoms. We construct an algorithm that directly solves this\nproblem for large finite portions of the crystals and retrieves the periodicity\nof the match subsequently. We demonstrate its capacity to describe\ntransformation pathways between known polymorphs and to reproduce\nexperimentally realized structures of semi-coherent interfaces. Additionally,\nfrom our findings we define a rigorous metric for measuring distances between\ncrystal structures that can be used to properly quantify their geometric\n(Euclidean) closeness."
    },
    {
        "anchor": "Enhancing hole mobility in III-V semiconductors: Transistors based on III-V semiconductor materials have been used for a\nvariety of analog and high frequency applications driven by the high electron\nmobilities in III-V materials. On the other hand, the hole mobility in III-V\nmaterials has always lagged compared to group-IV semiconductors such as silicon\nand germanium. In this paper we explore the used of strain and heterostructure\ndesign guided by bandstructure modeling to enhance the hole mobility in III-V\nmaterials. Parameters such as strain, valence band offset, effective masses and\nsplitting between the light and heavy hole bands that are important for\noptimizing hole transport are measured quantitatively using various\nexperimental techniques. A peak Hall mobility for the holes of 960cm2/Vs is\ndemonstrated and the high hole mobility is maintained even at high sheet\ncharge.",
        "positive": "Phonon and magnetic dimer excitations in Fe-based S=2 spin ladder\n  compound BaFe$_2$Se$_2$O: Raman scattering spectra of new Fe-based S=2 spin ladder compound\nBaFe$_2$Se$_2$O are measured in a temperature range between 15 K and 623 K. All\nsix A$_{1g}$ and two B$_{1g}$ Raman active modes of BaFe$_2$Se$_2$O, predicted\nby the factor-group analysis, have been experimentally observed at energies\nthat are in a rather good agreement with the lattice dynamics calculation. The\nantiferromagnetic long-range spin ordering in BaFe$_2$Se$_2$O below $T_N$=240 K\nleaves a fingerprint both in the A$_{1g}$ and B$_{1g}$ phonon mode linewidth\nand energy. In the energy range between 400 and 650 cm$^{-1}$ we have observed\nmagnetic excitation related structure in the form of magnon continuum, with the\npeaks corresponding to the singularities in the one dimensional density of\nmagnon states. The onset value of magnetic continuum (2$\\Delta_{S}$) is found\nat about 437 cm$^{-1}$ at 15 K. The magnetic continuum disappears at about 623\nK, which lead us to conclude that the short-range magnetic ordering in\nBaFe$_2$Se$_2$O exists apparently up to 2.6$T_N$."
    },
    {
        "anchor": "Bridging Borophene and Metal Surfaces: Structural, Electronic, and\n  Electron Transport Properties: Currently, solid interfaces composed of two-dimensional materials (2D) in\ncontact with metal surfaces (m-surf) have been the subject of intense research,\nwhere the borophene bilayer (BBL) has been considered a prominent material for\nthe development of electronic devices based on 2D platforms. In this work, we\npresent a theoretical study of the energetic, structural, and electronic\nproperties of the BBL/m-surf interface, with m-surf = Ag, Au, and Al (111)\nsurfaces, and the electronic transport properties of BBL channels connected to\nthe BBL/m-surf top contacts. We find that the bottom-most BBL layer becomes\nmetalized, due to the orbital hybridization with the metal surface states,\nresulting in BBL/m-surf ohmic contacts, meanwhile, the inner and top-most boron\nlayers kept their semiconducting character. The net charge transfers reveal\nthat BBL has become $n$-type ($p$-type) doped for m-surf = Ag, and Al (= Au). A\nthorough structural characterization of the BBL/m-surf interface, using a\nseries of simulations of the X-ray photoelectron spectra, shows that the\nformation of BBL/m-surf interface is characterized by a redshift of the B-$1s$\nspectra. Further electronic transport results revealed the emergence of a\nSchottky barrier between 0.1 and 0.2\\,eV between the BBL/m-surf contact and the\nBBL channels. We believe that our findings are timely, bringing important\ncontributions to the applicability of borophene bilayers for developing 2D\nelectronic devices.",
        "positive": "InSe: a two-dimensional material with strong interlayer coupling: Atomically thin, two-dimensional (2D) indium selenide (InSe) has attracted\nconsiderable attention due to large tunability in the band gap (from 1.4 to 2.6\neV) and high carrier mobility. The intriguingly high dependence of band gap on\nlayer thickness may lead to novel device applications, although its origin\nremains poorly understood, and generally attributed to quantum confinement\neffect. In this work, we demonstrate via first-principles calculations that\nstrong interlayer coupling may be mainly responsible for this phenomenon,\nespecially in the fewer-layer region, and it could also be an essential factor\ninfluencing other material properties of {\\beta}-InSe and {\\gamma}-InSe.\nExistence of strong interlayer coupling manifests itself in three aspects: (i)\nindirect-to-direct band gap transitions with increasing layer thickness; (ii)\nfan-like frequency diagrams of the shear and breathing modes of few-layer\nflakes; (iii) strong layer-dependent carrier mobilities. Our results indicate\nthat multiple-layer InSe may be deserving of attention from FET-based\ntechnologies and also an ideal system to study interlayer coupling, possibly\ninherent in other 2D materials."
    },
    {
        "anchor": "Stress-Induced Phase Transitions in Nanoscale CuInP$_2$S$_6$: Using Landau-Ginsburg-Devonshire approach and available experimental results\nwe reconstruct the thermodynamic potential of the layered ferroelectric\nCuInP$_2$S$_6$ (CIPS), which is expected to be applicable a wide range of\ntemperatures and applied pressures. The analysis of temperature dependences of\nthe dielectric permittivity and lattice constants for different applied\npressures unexpectedly reveals the critically important role of the nonlinear\nelectrostriction in this material. With the nonlinear electrostriction included\nwe calculated temperature and pressure phase diagrams and spontaneous\npolarization of bulk CIPS. Using the coefficients of the reconstructed\nfour-well thermodynamic potential, we study the strain-induced phase\ntransitions in thin epitaxial CIPS films, as well as the stress-induced phase\ntransitions in CIPS nanoparticles, which shape varies from prolate needles to\noblate disks. We reveal the strong influence of the mismatch strain, elastic\nstress and shape anisotropy on the polar properties and phase diagrams of\nnanoscale CIPS. Also, we derived analytical expressions, which allow the\nelastic control of the nanoscale CIPS polar properties. Hence obtained results\ncan be of particular interest for the strain-engineering of nanoscale layered\nnanoferroelectrics.",
        "positive": "Extending the kinetic and thermodynamic limits of molecular-beam epitaxy\n  utilizing suboxide sources or metal-oxide catalyzed epitaxy: We observe a catalytic mechanism during the growth of III-O and IV-O\nmaterials by suboxide molecular-beam epitaxy ($S$-MBE). By supplying the\nmolecular catalysts In$_2$O and SnO we increase the growth rates of Ga$_2$O$_3$\nand In$_2$O$_3$. This catalytic action is explained by a metastable adlayer\n$A$, which increases the reaction probability of the reactants Ga$_2$O and\nIn$_2$O with active atomic oxygen, leading to an increase of the growth rates\nof Ga$_2$O$_3$ and In$_2$O$_3$. We derive a model for the growth of binary\nIII-O and IV-O materials by $S$-MBE and apply these findings to a generalized\ncatalytic description for metal-oxide catalyzed epitaxy (MOCATAXY), applicable\nto elemental and molecular catalysts. We derive a mathematical description of\n$S$-MBE and MOCATAXY providing a computational framework to set growth\nparameters in previously inaccessible kinetic and thermodynamic growth regimes\nwhen using the aforementioned catalysis. Our results indicate MOCATAXY takes\nplace with a suboxide catalyst rather than with an elemental catalyst. As a\nresult of the growth regimes achieved, we demonstrate a Ga$_2$O$_3$/Al$_2$O$_3$\nheterostructure with unrivaled crystalline quality, paving the way to the\npreparation of oxide device structures with unprecedented perfection."
    },
    {
        "anchor": "Stabilization of Ferroelectric Hf0.5Zr0.5O2 Epitaxial Films via\n  Monolayer Reconstruction Driven by Interfacial Redox Reaction: The binary fluorite oxide Hf0.5Zr0.5O2 tends to grab a significant amount of\nnotice due to the distinct and superior ferroelectricity found in its\nmetastable phase. Stabilizing the metastable ferroelectric phase and\ndelineating the underlying growth mechanism, however, are still challenging.\nRecent discoveries of metastable ferroelectric Hf0.5Zr0.5O2 epitaxially grown\non structurally dissimilar perovskite oxides have triggered intensive\ninvestigations on the ferroelectricity in materials that are nonpolar in bulk\nform. Nonetheless, the growth mechanism for the unique fluorite/perovskite\nheterostructures has yet to be fully explored. Here we show that the metastable\nferroelectric Hf0.5Zr0.5O2 films can be stabilized even on a\none-unit-cell-thick perovskite La0.67Sr0.33MnO3 buffer layer. In collaboration\nwith scanning transmittance electron microscopy (STEM) based characterizations,\nwe show that monolayer reconstruction driven by interfacial redox reactions\nplays a vital role in the formation of a unique heterointerface between the two\nstructurally dissimilar oxides, providing the template monolayer that\nfacilitates the epitaxial growth of the metastable HZO films. Our findings\noffer significant insights into the stabilization mechanism of the\nferroelectric Hf0.5Zr0.5O2, and this mechanism could be extended for exploring\nfunctional metastable phases of various metal oxides.",
        "positive": "Acoustic Axes in Elasticity: New results are presented for the degeneracy condition of elastic waves in\nanisotropic materials. The existence of acoustic axes involves a traceless\nsymmetric third order tensor that must vanish identically. It is shown that all\nprevious representations of the degeneracy condition follow from this acoustic\naxis tensor. The conditions for existence of acoustic axes in elastic crystals\nof orthorhombic, tetragonal, hexagonal and cubic (RTHC) symmetry are\nreinterpreted using the geometrical methods developed here. Application to\nweakly anisotropic solids is discussed, and it is shown that the satisfaction\nof the acoustic axes conditions to first order in anisotropy does not in\ngeneral coincide with true acoustic axes."
    },
    {
        "anchor": "Photo-excitation of a light-harvesting supra-molecular triad: a\n  Time-Dependent DFT study: We present the first time-dependent density-functional theory (TDDFT)\ncalculation on a light harvesting triad carotenoid-diaryl-porphyrin-C60.\nBesides the numerical challenge that the ab initio study of the electronic\nstructure of such a large system presents, we show that TDDFT is able to\nprovide an accurate description of the excited state properties of the system.\nIn particular we calculate the photo-absorption spectrum of the supra-molecular\nassembly, and we provide an interpretation of the photo-excitation mechanism in\nterms of the properties of the component moieties. The spectrum is in good\nagreement with experimental data, and provides useful insight on the\nphoto-induced charge transfer mechanism which characterizes the system.",
        "positive": "Na9Bi5Os3O24: A Unique Diamagnetic Oxide Featuring a Pronouncedly\n  Jahn-Teller Compressed Octahedral Coordination of Osmium(VI): The Jahn-Teller theorem constitutes one of the most popular and stringent\nconcepts, applicable to all fields of chemistry. In open shell transition\nelements chemistry and physics, 3d4, 3d9, and 3d7(low-spin) configurations in\noctahedral complexes serve as particular illustrative and firm examples, where\na striking change (distortion) in local geometry is associated to a substantial\nreduction of electronic energy. However, there has been a lasting debate, about\nthe fact that the octahedra are found to exclusively elongate, (at least for eg\nelectrons). Against this background, the title compound displays two marked\nfeatures, (1) the octahedron of oxygen atoms around Os6+ (d2) is drastically\ncompressed, in contrast to the standard JT expectations, and (2) the splitting\nof the t2g set induced by this compression is extreme, such that a diamagnetic\nground state results. What we see is obviously a Jahn-Teller distortion\nresulting in a compression of the respective octahedron and acting on the t2g\nset of orbitals. Both these issues are unprecedented. Noteworthy, the splitting\ninto a lower dxy (hosting two d electrons with opposite spin) and two higher\ndxz and dyz orbitals is so large that for the first time ever the Hund's\ncoupling for t2g electrons is overcome. We show that these effects are not\nforced by structural frustration, the structure offers sufficient space for Os\nto shift the apical oxygen atoms to a standard distance. Local electronic\neffects appear to be responsible, instead. The relevance of these findings is\nfar reaching, since they provide insights in the hierarchy of perturbations\ndefining ground states of open shell electronic systems. The system studied\nhere, offers substantially more structural and compositional degrees of\nfreedom, such that a configuration could form that enables Os6+ to adopt its\napparently genuine diamagnetic ground state."
    },
    {
        "anchor": "Accurate determination of electron-hole asymmetry and next-nearest\n  neighbor hopping in graphene: The next-nearest neighbor hopping term t' determines a magnitude and, hence,\nimportance of several phenomena in graphene, which include self-doping due to\nbroken bonds and the Klein tunneling that in the presence of t' is no longer\nperfect. Theoretical estimates for t' vary widely whereas a few existing\nmeasurements by using polarization resolved magneto-spectroscopy have found\nsurprisingly large t', close or even exceeding highest theoretical values. Here\nwe report dedicated measurements of the density of states in graphene by using\nhigh-quality capacitance devices. The density of states exhibits a pronounced\nelectron-hole asymmetry that increases linearly with energy. This behavior\nyields t' approx -0.30 eV +-15%, in agreement with the high end of theory\nestimates. We discuss the role of electron-electron interactions in determining\nt' and overview phenomena which can be influenced by such a large value of t'.",
        "positive": "Beyond the local approximation to exchange and correlation: the role of\n  the Laplacian of the density in the energy density of Si: We model the exchange-correlation (XC) energy density of the Si crystal and\natom as calculated by variational Monte Carlo (VMC) methods with a gradient\nanalysis beyond the local density approximation (LDA). We find the Laplacian of\nthe density to be an excellent predictor of the discrepancy between VMC and LDA\nenergy densities in each system. A simple Laplacian-based correction to the LDA\nenergy density is developed by means of a least square fit to the VMC XC energy\ndensity for the crystal, which fits the homogeneous electron gas and Si atom\nwithout further effort."
    },
    {
        "anchor": "Pressure Effect on Band Inversion in AECd2As2: Recent studies have predicted that magnetic EuCd2As2 can host several\ndifferent topological states depending on its magnetic order, including a\nsingle pair of Weyl points. Here we report on the bulk properties and band\ninversion induced by pressure in the non-magnetic analogs AECd2As2 (AE = Ca,\nSr, Ba) as studied with density functional theory calculations. Under ambient\npressure we find these compounds are narrow band gap semiconductors, in\nagreement with experiment. The size of the band gap is dictated by both the\nincreasing ionicity across the AE series which tends to increase the band gap,\nas well as the larger nearest neighbor Cd-As distance from increasing atomic\nsize which can decrease the band gap because the conduction band edge is an\nanti-bonding state derived mostly from Cd 5s orbitals. The combination of these\ntwo competing effects results in a non-monotonic change of the band gap size\nacross the AE series with SrCd2As2 having the smallest band gap among the three\ncompounds. The application of negative pressure reduces this band gap and\ncauses the band inversion between the Cd 5s and As 4p orbitals along the\n${\\Gamma}$-A direction to induce a pair of Dirac points. The topological nature\nof the Dirac points is then confirmed by finding the closed Fermi arcs on the\n(10-10) surface.",
        "positive": "2.5 eV Pulsed Cathodoluminesce band of silicon dioxide: Room-temperature (RT) Pulsed Cathodoluminescence (PCL) spectra of a set of\npure synthetic (both crystalline and amorphous) silicon dioxide materials were\nstudied. It is shown, that the PCL spectra of all samples (both amorphous and\ncrystalline) possess a separate band at 495 nm (2.5 eV). This band is the most\nintensive one in PCL spectra of disordered materials. The RT PCL band at 495 nm\n(2.5 eV) of {\\alpha}-quartz single crystal is polarized in XY crystalline plane\n(perpendicular to the $3^{rd}$ order symmetry axis). The structure of this band\nwas detected. It consists of three peaks: at 480$\\pm$2 nm (2.58$\\pm$0.01 eV),\n487$\\pm$ nm (2.55$\\pm$0.01 eV) and 493$\\pm$2 nm (2.52$\\pm$0.01 eV). Energy\nseparation between peaks is equal in order of magnitude to energies of\n$Li_{x}O_{y}$ molecular vibrations and to the energy of optical phonon in\n{\\alpha}-quartz. It is shown, that the emission band at 495 nm (2.5 eV) in RT\nPCL spectra of {\\alpha}-quartz single crystal is related to the bulk emission\ncenters, not to the surface-related ones. The annealing behaviors of the 495 nm\n(2.5 eV) bands in spectrum of amorphous and crystalline $SiO_{2}$ are close to\neach other. This fact may be the manifestation of identical origin of these\nbands. The following explanation of experimental data is proposed: the origin\nof 495 nm (2.5 eV) band in pure silicon dioxide is related to the recombination\nof non-bridging oxygen $NBO^{-}-Li^{+}$ centers."
    },
    {
        "anchor": "One-Dimensional Edge States with Giant Spin Splitting in a Bismuth Thin\n  Film: To realize a one-dimensional (1D) system with strong spin-orbit coupling is a\nbig challenge in modern physics, since the electrons in such a system are\npredicted to exhibit exotic properties unexpected from the 2D or 3D\ncounterparts, while it was difficult to realize genuine physical properties\ninherent to the 1D system. We demonstrate the first experimental result that\ndirectly determines the purely 1D band structure by performing spin-resolved\nangle-resolved photoemission spectroscopy of Bi islands on a silicon surface\nthat contains a metallic 1D edge structure with unexpectedly large Rashba-type\nspin-orbit coupling suggestive of the nontopological nature. We have also found\na sizable out-of-plane spin polarization of the 1D edge state, consistent with\nour first-principles band calculations. Our result provides a new platform to\nrealize exotic quantum phenomena at the 1D edge of the strong\nspin-orbit-coupling systems.",
        "positive": "Processing, electronic properties and applications of Carbon-based\n  nanocomposites: The last two decades, in particular, have witnessed a large volume of\nresearch revolving around structure-property correlation in Carbon based\nnanocomposites, synthesized by several methods.In the simplest of terms, the\nelectronic properties of these nanomaterials, which form the present context of\ndiscussion, vary mainly as a function of three parameters, out of which 2 are\nprocess parameters (viz. the kind of reinforcement and method of synthesis) and\none is a structure-dependent parameter which is highly influenced by the two\naforementioned process parameters and plays a vital role in determining the\nionic and electronic transport phenomenon in these materials. To be more\nspecific in the context of structure dependent parameter, the interaction\nbetween electrons and the equilibrium 0D (point) defects, along with different\ntypes of interfaces, plays a crucial role in the understanding of electronic\nproperties, apart from physical and chemical properties in these materials.\nThese materials find applications in a large number of sectors, such as\nnanoelectronics, supercapacitors, absorbent, photocatalytic, photovoltaic,\nsolar cells, sensors, and energy storage due to their exceptional electronic,\nmechanical and chemical properties. The present chapter will intend to focus\nprimarily on providing a brief overview of the state-of-the-art on research\nalong with detailed discussions on some recent developments in determining and\nunderstanding electronic properties of some conventional Carbon-based\nnanocomposites (synthesized by several different techniques) based on the\nstructure property correlation of these materials and finally, address some of\nthe significant challenges in this field."
    },
    {
        "anchor": "Intercalation of Few-Layer Graphite Flakes with FeCl3: Raman\n  Determination of Fermi Level, Layer Decoupling and Stability: We use anhydrous ferric chloride (FeCl3) to intercalate graphite flakes\nconsisting of 2 to 4 graphene layers and to dope graphene monolayers. The\nintercalant, staging, stability and doping of the resulting intercalation\ncompounds (ICs) are characterized by Raman scattering. The G peak of monolayer\ngraphene heavily-doped by FeCl3 upshifts to~1627cm-1. 2-4 layer ICs have\nsimilar upshifts, and a Lorentzian lineshape for the 2D band, indicating that\neach layer behaves as a decoupled heavily doped monolayer. By performing Raman\nmeasurement at different excitation energies we show that, for a given doping\nlevel, the 2D peak can be suppressed by Pauli blocking for laser energy below\nthe doping level. Thus, multi-wavelength Raman spectroscopy allows a direct\nevaluation of the Fermi level, complementary to that derived by Raman\nmeasurements at excitation energies higher than the doping level. We estimate a\nFermi level shift of~0.9eV. These ICs are ideal test-beds for the physical and\nchemical properties of heavily-doped graphenes.",
        "positive": "Hydrogen phase-IV characterization by full account of quantum\n  anharmonicity: We devise a framework to compute accurate phonons in molecular crystals even\nin case of strong quantum anharmonicity. Our approach is based on the\ncalculation of the static limit of the phononic Matsubara Green's function from\npath integral molecular dynamics simulations. Our method enjoys a remarkably\nlow variance, which allows one to compute accurate phonon frequencies after a\nfew picoseconds of nuclear dynamics, and it is further stabilized by the use of\nappropriate constrained displacement operators. We applied it to solid hydrogen\nat high pressure. For phase III, our predicted infrared (IR) and Raman active\nvibrons agree very well with experiments. We then characterize the crystalline\nsymmetry of phase IV by direct comparison with vibrational data and we\ndetermine the character of its Raman and IR vibron peaks."
    },
    {
        "anchor": "Low-temperature heat transfer in nanowires: The new regime of low-temperature heat transfer in suspended nanowires is\npredicted. It takes place when (i) only ``acoustic'' phonon modes of the wire\nare thermally populated and (ii) phonons are subject to the effective elastic\nscattering. Qualitatively, the main peculiarities of heat transfer originate\ndue to appearance of the flexural modes with high density of states in the wire\nphonon spectrum. They give rise to the $T^{1/2}$ temperature dependence of the\nwire thermal conductance. The experimental situations where the new regime is\nlikely to be detected are discussed.",
        "positive": "Structure and Thermodynamics of the Mixed Alkali Alanates: The thermodynamics and structural properties of the hexahydride alanates\n(M2M'AlH6) with the elpasolite structure have been investigated. A series of\nmixed alkali alanates (Na2LiAlH6, K2LiAlH6 and K2NaAlH6) were synthesized and\nfound to reversibly absorb and desorb hydrogen without the need for a catalyst.\nPressure-composition isotherms were measured to investigate the thermodynamics\nof the absorption and desorption reactions with hydrogen. Isotherms for\ncatalyzed (4 mol% TiCl3) and uncatalyzed Na2LiAlH6 exhibited an increase in\nkinetics, but no change in the bulk thermodynamics with the addition of a\ndopant. A structural analysis using synchrotron x-ray diffraction showed that\nthese compounds favor the Fm-3m space group with the smaller ion (M') occupying\nan octahedral site. These results demonstrate that appropriate cation\nsubstitutions can be used to stabilize or destabilize the material and may\nprovide an avenue to improving the unfavorable thermodynamics of a number of\nmaterials with promising gravimetric hydrogen densities."
    },
    {
        "anchor": "Observation of quasi-two-dimensional Dirac fermions in ZrTe5: Since the discovery of graphene, layered materials have attracted extensive\ninterests owing to their unique electronic and optical characteristics. Among\nthem, Dirac semimetal, one of the most appealing categories, has been a\nlong-sought objective in layered systems beyond graphene. Recently, layered\npentatelluride ZrTe5 was found to host signatures of Dirac semimetal. However,\nthe low Fermi level in ZrTe5 strongly hinders a comprehensive understanding of\nthe whole picture of electronic states through photoemission measurements,\nespecially in the conduction band. Here, we report the observation of Dirac\nfermions in ZrTe5 through magneto-optics and magneto-transport. By applying\nmagnetic field, we observe a square-root-B dependence of inter-Landau-level\nresonance and Shubnikov-de Haas (SdH) oscillations with non-trivial Berry\nphase, both of which are hallmarks of Dirac fermions. The angular-dependent SdH\noscillations show a clear quasi-two-dimensional feature with highly anisotropic\nFermi surface and band topology, in stark contrast to the 3D Dirac semimetal\nsuch as Cd3As2. This is further confirmed by the angle-dependent Berry phase\nmeasurements and the observation of bulk quantum Hall plateaus. The unique band\ndispersion is theoretically understood: the system is at the critical point\nbetween a 3D Dirac semimetal and a topological insulator phase. With the\nconfined interlayer dispersion and reducible dimensionality, our work\nestablishes ZrTe5 as an ideal platform for exploring exotic physical phenomena\nof Dirac fermions.",
        "positive": "Structure and soft magnetic properties of single-domain\n  Mg$_{1-x}$Ni$_x$Fe$_2$O$_4$ ($0 \\le x \\le 1.0$) nanocrystals: The effects of Ni$^{2+}$ substitution on the structure (lattice parameters,\ncations distribution, average cations radii, cation-cation/anion bond lengths\nand angles) and the soft magnetic properties of Mg$_{1-x}$Ni$_x$Fe$_2$O$_4$ ($0\n\\le x \\le 1.0$) nanocrystals have been studied by x-ray diffraction with\nRietveld refinement, transmittance electron microscopy, Mossbauer spectroscopy\nand magnetization measurements. The mostly inverse spinel structure was found\nin MgFe$_2$O$_4$ nanoparticles and the inversion factor is further increased by\nNi-substitution up to a complete inversion in NiFe$_2$O$_4$. The synthesized\nferrites with a small particle size (20 - 30 nm) exhibit soft magnetic\nproperties of a single-domain behavior with critical domain size about 30 - 40\nnm. An observed monotonic increase in magnetization and drastic decrease in\ncoercivity at 5 K by Ni-substitution result in a lowest anisotropy constant Ku\n(2.8 kJ/m3) for x = 0.5. We discuss the evolution of magnetic properties by\nNi-substitution in a correlation with a subsequent cations-redistribution\nbetween sites of the two sublattices and corresponding structural changes in\nthe inter-ionic distances."
    },
    {
        "anchor": "Gate Tunable Magneto-resistance of Ultra-Thin WTe2 Devices: In this work, the magneto-resistance (MR) of ultra-thin WTe2/BN\nheterostructures far away from electron-hole equilibrium is measured. The\nchange of MR of such devices is found to be determined largely by a single\ntunable parameter, i.e. the amount of imbalance between electrons and holes. We\nalso found that the magnetoresistive behavior of ultra-thin WTe2 devices is\nwell-captured by a two-fluid model. According to the model, the change of MR\ncould be as large as 400,000%, the largest potential change of MR among all\nmaterials known, if the ultra-thin samples are tuned to neutrality when\npreserving the mobility of 167,000 cm2V-1s-1 observed in bulk samples. Our\nfindings show the prospects of ultra-thin WTe2 as a variable magnetoresistance\nmaterial in future applications such as magnetic field sensors, information\nstorage and extraction devices, and galvanic isolators. The results also\nprovide important insight into the electronic structure and the origin of the\nlarge MR in ultra-thin WTe2 samples.",
        "positive": "Fundamental Materials Research and the Course of Human Civilization: Unless we change direction, we are likely to wind up where we are headed.\n(Ancient Chinese proverb)"
    },
    {
        "anchor": "Structural pathways for ultrafast melting of optically excited thin\n  polycrystalline Palladium films: Due to its extremely short timescale, the non-equilibrium melting of metals\nis exceptionally difficult to probe experimentally. The knowledge of melting\nmechanisms is thus based mainly on the results of theoretical predictions. This\nwork reports on the investigation of ultrafast melting of thin polycrystalline\nPd films studied by optical laser pump - X-ray free-electron laser probe\nexperiments and molecular-dynamics simulations. By acquiring X-ray diffraction\nsnapshots with sub-picosecond resolution, we capture the sample's atomic\nstructure during its transition from the crystalline to the liquid state.\nBridging the timescales of experiments and simulations allows us to formulate a\nrealistic microscopic picture of melting. We demonstrate that the existing\nmodels of strongly non-equilibrium melting, developed for systems with\nrelatively weak electron-phonon coupling, remain valid even for ultrafast\nheating rates achieved in femtosecond laser-excited Pd. Furthermore, we\nhighlight the role of pre-existing and transiently generated crystal defects in\nthe transition to the liquid state.",
        "positive": "Screw dislocation in zirconium: An ab initio study: Plasticity in zirconium is controlled by 1/3<1-210> screw dislocations\ngliding in the prism planes of the hexagonal close-packed structure. This\nprismatic and not basal glide is observed for a given set of transition metals\nlike zirconium and is known to be related to the number of valence electrons in\nthe d band. We use ab initio calculations based on the density functional\ntheory to study the core structure of screw dislocations in zirconium.\nDislocations are found to dissociate in the prism plane in two partial\ndislocations, each with a pure screw character. Ab initio calculations also\nshow that the dissociation in the basal plane is unstable. We calculate then\nthe Peierls barrier for a screw dislocation gliding in the prism plane and\nobtain a small barrier. The Peierls stress deduced from this barrier is lower\nthan 21 MPa, which is in agreement with experimental data. The ability of an\nempirical potential relying on the embedded atom method (EAM) to model\ndislocations in zirconium is also tested against these ab initio calculations."
    },
    {
        "anchor": "Role of carbon nanotube diameter on thermal interfacial resistance\n  through the analysis of vibrational mismatch: A Molecular Dynamics approach: Carbon nanotube (CNT) have been known to increase the heat transfer at the\nsolid-liquid interfaces, but have a limitation due to the interfacial thermal\nresistance. Vibrational mismatch at the interface leads to this interfacial\nthermal resistance, which plays an important role in energy transfer at the\nboundary. Negligible work has been reported on the influence of CNT diameter on\nthe resistance through the vibrational mismatch study. Molecular dynamics\nsimulations have been performed to investigate the effect of CNT diameter on\ninterfacial resistance between carbon nanotube (CNT) and water molecules. This\nwork is an effort to understand the heat transfer phenomenon at the interface\nby quantifying the vibrational mismatch. Analysis of the vibrational spectra of\nCNT and water molecules is done to study the effect of CNT diameter on\ninterfacial resistance. Starting with the initial configuration, and\nequilibrating the system of CNT and water molecules at 300 K and 1 atm, the CNT\ntemperature is raised to 700 K by velocity rescaling. This system is now\nallowed to relax as a micro-canonical ensemble. Based on the lumped capacitance\nanalysis, the time constant of the CNT temperature response is determined,\nwhich is then used to compute the interfacial thermal resistance. The\ninterfacial thermal resistance is observed to be relatively higher for the\nlarger diameter nanotube. This is attributed to the higher vibrational mismatch\nexisting for larger diameter CNT as a result of low overlapping region between\nvibrational density states of CNT and water molecules. For smaller diameter\nCNT, the interfacial thermal resistance is low which results in the efficient\nheat transfer at the interface thus, emphasizing the indispensable role of\nlarger diameter CNTs in the cooling applications.",
        "positive": "First Principles Study of 2D Ring-Te and its Electrical Contact with\n  Topological Dirac Semimetal: In recent years, researchers have manifested their interest in the\ntwo-dimensional (2D) mono-elemental materials of group-VI elements because of\ntheir excellent optoelectronic, photovoltaic and thermoelectric properties.\nDespite the intensive recent research efforts, there is still a possibility of\nnovel 2D allotropes of these elements due to their multivalency nature. Here,\nwe have predicted a novel 2D allotrope of tellurium (ring-Te) using density\nfunctional theory. Its stability is confirmed by phonon and ab-initio molecular\ndynamics simulations. The ring-Te has an indirect band gap of 0.69 eV (1.16 eV)\nat PBE (HSE06) level of theories and undergoes an indirect-direct band gap\ntransition under the tensile strain. The higher carrier mobility of holes\n(~103cm$^2$V$^{-1}$s$^{-1}$), good UV-visible light absorption ability and low\nexciton binding (~0.35 eV) of ring-Te gives rise to its potential applications\nin optoelectronic devices. Further, the electrical contact of ring-Te with\ntopological Dirac semimetal (sq-Te) under the influence of electric field shows\nthat the Schottky barriers and contact types can undergo transition from p-type\nto n-type Schottky contact and then to ohmic contact at higher electric field.\nOur study provides an insight into the physics of designing high-performance\nelectrical coupled devices composed of 2D semiconductors and topological\nsemimetals."
    },
    {
        "anchor": "Knitting quantum knots: Topological phase transitions in Two-Dimensional\n  systems: We start by describing a symmetry enforced nodal line semi-metal (NLSM) in\nthe 2D flat form of honeycomb Group - V and its non trivial thermo-electric\nresponse. We will then proceed to show that, upon buckling, the system\nundergoes its dirac-merging phase transitions. Further buckling leads to these\nunpinned Dirac cones annihilating in pairs at two distinct critical angle\nleading to a second topological phase transition to an insulating state. We\nthen show that this seemingly innocuous insulating state is indeed a weak\ntopological crystalline insulator. Furthermore, upon closer look, this\ninsulating state turns out to be a Higher Order Topological Insulator (HOTI)\nthat is protected by $\\mathcal{S}_6$ symmetry. In a broader context, we will\nsee that the the topological properties of buckled Group - $V$ stem from the\nfact that they topologically belong to the class of Obstructed Atomic Limit\n(OAL) insulators. Combining all these, we will prove that annihilating pairs of\nDirac fermions necessitate a topological phase transition from the critical\nsemi-metallic phase to an OAL insulator phase. We also uncover the rich set of\nphases in the phase diagram in case of annihilating Dirac fermions and study\ntheir entanglement properties using entanglement entropy. Finally, based on the\nnon-trivial topology of these systems, we propose the conceptual design of a\nquantized switch that is protected by topology. Last part of the thesis\ninvolves the remarkable discovery of a spin polarized 2D electron/hole gas at\nthe surfaces of a well known system - LiCoO2.",
        "positive": "Quantum spin Hall effect and topological phase transitions in honeycomb\n  antiferromagnets: While the quantum spin Hall (QSH) effect and antiferromagnetic order\nconstitute two of the most promising phenomena for embedding basic spintronic\nconcepts into future technologies, almost all of the QSH insulators known to\ndate are non-magnetic. Here, based on tight-binding arguments and\nfirst-principles theory, we predict two-dimensional antiferromagnets with\nhoneycomb lattice structure to exhibit the QSH effect due to the combined\nsymmetry of time reversal and spatial inversion. We identify functionalized Sn\nfilms as experimentally feasible examples which reveal large band gaps\nrendering these systems ideal for energy efficient spintronics applications.\nRemarkably, we discover that tensile strain can tune the magnetic order in\nthese materials, accompanied by a topological phase transition from the QSH to\nthe quantum anomalous Hall phase."
    },
    {
        "anchor": "V$_5$S$_8$: a Kondo lattice based on intercalation of van der Waals\n  layered transition metal dichalcogenide: Since the discovery of graphene, a tremendous amount of two dimensional (2D)\nmaterials have surfaced. Their electronic properties can usually be well\nunderstood without considering correlations between electrons. On the other\nhand, strong electronic correlations are known to give rise to a variety of\nexotic properties and new quantum phases, for instance, high temperature\nsuperconductivity, heavy fermions and quantum spin liquids. The study of these\nphenomena has been one of the main focuses of condensed matter physics. There\nis a strong incentive to introduce electronic correlations into 2D materials.\nVia intercalating a van der Waals layered compound VS$_2$, we show an emergence\nof a Kondo lattice, an extensively studied strongly correlated system, by\nmagnetic, specific heat, electrical and thermoelectric transport studies. In\nparticular, an exceptionally large Sommerfeld coefficient, 440\nmJ$\\cdot$K$^{-2}\\cdot$mol$^{-1}$, indicates a strong electron correlation. The\nobtained Kadowaki-Woods ratio, $2.7\\times 10^{-6}$\n$\\mu\\Omega\\cdot$cm$\\cdot$mol$^2\\cdot$K$^2\\cdot$mJ$^{-2}$, also supports the\nstrong electron-electron interaction. The temperature dependence of the\nresistivity and thermopower corroborate the Kondo lattice picture. The\nintercalated compound is one of a few rare examples of $d$-electron Kondo\nlattices. We further show that the Kondo physics persists in ultra-thin films.\nThis work thus demonstrates a route to generate strong correlations in 2D\nmaterials.",
        "positive": "Rare-earth-free ferrimagnetic Mn4N sub-20 nm thin films as\n  high-temperature spintronic material: Ferrimagnetic alloy thin films that exhibit perpendicular (out-of-plane)\nmagnetic anisotropy (PMA) with low saturation magnetization, such as GdCo and\nMn4N, were predicted to be favorable for hosting small Neel skyrmions for room\ntemperature applications. Due to the exponential decay of interfacial\nDzyaloshinskii-Moriya interaction (DMI) and the limited range of\nspin-orbit-torques, which can be used to drive skyrmion motion, the thickness\nof the ferrimagnetic layer has to be small, preferably under 20 nm. While there\nare examples of sub-20 nm, rare earth-transition metal (RE-TM), ferrimagnetic\nthin films fabricated by sputter deposition, to date rare-earth-free sub-20 nm\nMn4N films with PMA have only been reported to be achieved by molecular beam\nepitaxy, which is not suitable for massive production. Here we report the\nsuccessful thermal growth of sub-20 nm Mn4N films with PMA at 400-450 {\\deg}C\nsubstrate temperatures on MgO substrates by reactive sputtering. The Mn4N films\nwere achieved by reducing the surface roughness of MgO substrate through a\nhigh-temperature vacuum annealing process. The optimal films showed low\nsaturation magnetization (Ms = 43 emu/cc), low magnetic anisotropy energy (0.7\nMerg/cc), and a remanent magnetization to saturation magnetization ratio\n(Mr/Ms) near 1 at room temperature. Preliminary ab-initio density functional\ntheory (DFT) calculations have confirmed the ferrimagnetic ground state of Mn4N\ngrown on MgO. The magnetic properties, along with the high thermal stability of\nMn4N thin films in comparison with RE-TM thin films, provide the platform for\nfuture studies of practical skyrmion-based spintronic materials."
    },
    {
        "anchor": "Self-assembled ErSb nanostructures of tunable shape and orientation:\n  growth and plasmonic properties: Self-assembled, semimetallic ErSb single crystal nanostructures, grown by\nmolecular beam epitaxy, are embedded within a semiconductor GaSb matrix.\nFormation, evolution and orientation of a variety of nanostructures, including\nspherical nanoparticles, elongated nanorods, octagonal shaped nanowires\noriented along the surface normal and nanowires oriented in the growth plane,\nare controlled simply by the Er fraction. The plasmonic properties of the\nsemimetal/semiconductor composites are characterized and quantified by three\npolarization-resolved spectroscopy techniques, spanning more than three orders\nof magnitude in frequency from 100 GHz up to 300 THz. The effect of the size,\nshape and orientation of the nanostructures is characterized by\npolarization-sensitive response and modeled by a Maxwell-Garnett effective\nmedium theory.",
        "positive": "Fast domain wall motion induced by antiferromagnetic spin dynamics at\n  the angular momentum compensation temperature of ferrimagnets: Antiferromagnetic spintronics is an emerging research field which aims to\nutilize antiferromagnets as core elements in spintronic devices. A central\nmotivation toward this direction is that antiferromagnetic spin dynamics is\nexpected to be much faster than ferromagnetic counterpart because\nantiferromagnets have higher resonance frequencies than ferromagnets. Recent\ntheories indeed predicted faster dynamics of antiferromagnetic domain walls\n(DWs) than ferromagnetic DWs. However, experimental investigations of\nantiferromagnetic spin dynamics have remained unexplored mainly because of the\nimmunity of antiferromagnets to magnetic fields. Furthermore, this immunity\nmakes field-driven antiferromagnetic DW motion impossible despite rich physics\nof field-driven DW dynamics as proven in ferromagnetic DW studies. Here we show\nthat fast field-driven antiferromagnetic spin dynamics is realized in\nferrimagnets at the angular momentum compensation point TA. Using rare-earth\n3d-transition metal ferrimagnetic compounds where net magnetic moment is\nnonzero at TA, the field-driven DW mobility remarkably enhances up to 20 km/sT.\nThe collective coordinate approach generalized for ferrimagnets and atomistic\nspin model simulations show that this remarkable enhancement is a consequence\nof antiferromagnetic spin dynamics at TA. Our finding allows us to investigate\nthe physics of antiferromagnetic spin dynamics and highlights the importance of\ntuning of the angular momentum compensation point of ferrimagnets, which could\nbe a key towards ferrimagnetic spintronics."
    },
    {
        "anchor": "Electronic stopping power in insulators from first principles: Using time-dependent density-functional theory we calculate from first\nprinciples the rate of energy transfer from a moving proton or antiproton to\nthe electrons of an insulating material, LiF. The behavior of the electronic\nstopping power versus projectile velocity displays an effective threshold\nvelocity of ~0.2 a.u. for the proton, consistent with recent experimental\nobservations, and also for the antiproton. The calculated proton/antiproton\nstopping-power ratio is ~2.4 at velocities slightly above the threshold (v~0.4\na.u.), as compared to the experimental value of 2.1. The projectile energy loss\nmechanism is observed to be stationary and extremely local.",
        "positive": "Association Between Gold Grain Orientation And Its Periodic Steps Formed\n  At The Gold/Substrate Interface: Nanoscale step structures have attracted recent interest owing to their\nimportance in both fundamental and applied research, for example in adsorption,\nin catalysis, and in directing nanowire growth. Here, we used a\ntemplate-stripping method to obtain vicinal-like surface structures on grains\nof polycrystalline gold and investigated the effect of annealing temperature on\nthe formation of these surfaces."
    },
    {
        "anchor": "Modelling Grain Boundaries in Polycrystalline Halide Perovskite Solar\n  Cells: Solar cells are semiconductor devices that generate electricity through\ncharge generation upon illumination. For optimal device efficiency, the\nphoto-generated carriers must reach the electrical contact layers before they\nrecombine. A deep understanding of the recombination process and transport\nbehavior is essential to design better devices. Halide perovskite solar cells\nare commonly made of a polycrystalline absorber layer, but there is no\nconsensus on the nature and role of grain boundaries. This review paper\nconcerns theoretical approaches for the investigation of extended defects. We\nintroduce recent computational studies on grain boundaries, and their influence\non point defect distributions, in halide perovskite solar cells. We conclude\nthe paper with discussion of future research directions.",
        "positive": "Interlayer Configurations in Twisted Bilayers of Folded Graphene: The folding of monolayer graphene leads to new layered systems, termed\ntwisted bilayer graphene (TBG), generally displaying a certain interlayer\nrotation away from crystallographic alignment. We here present an atomic force\nmicroscopy study on folded graphene, revealing unexpectedly large twist angle\ndependent modulations of ~3 angstrom in interlayer distance. At the TBG\nsurface, we find enhanced friction attributable to superlubricity in between\nincommensurate layers. At the bended edge, the radius of curvature scales with\nthe folded length, congruent to earlier studies on carbon nanotubes."
    },
    {
        "anchor": "Highly tunable hybrid metamaterials employing split-ring resonators\n  strongly coupled to graphene surface plasmons: Metamaterials and plasmonics are powerful tools for unconventional\nmanipulation and harnessing of light. Metamaterials can be engineered to\npossess intriguing properties lacking in natural materials, such as negative\nrefractive index. Plasmonics offers capabilities to confine light in\nsubwavelength dimensions and to enhance light-matter interactions.\nRecently,graphene-based plasmonics has revealed emerging technological\npotential as it features large tunability, higher field-confinement and lower\nloss compared to metal-based plasmonics. Here,we introduce hybrid structures\ncomprising graphene plasmonic resonators efficiently coupled to conventional\nsplit-ring resonators, thus demonstrating a type of highly tunable\nmetamaterial, where the interaction between the two resonances reaches the\nstrong-coupling regime. Such hybrid metamaterials are employed as high-speed\nTHz modulators, exhibiting over 60% transmission modulation and operating speed\nin excess of 40 MHz. This device concept also provides a platform for exploring\ncavity-enhanced light-matter interactions and optical processes in graphene\nplasmonic structures for applications including sensing, photo-detection and\nnonlinear frequency generation.",
        "positive": "Theory of spin-polarized transport in ferromagnet-semiconductor\n  structures: Unified description of ballistic and diffusive transport: A theory of spin-polarized electron transport in ferromagnet-semiconductor\nheterostructures, based on a unified semiclassical description of ballistic and\ndiffusive transport in semiconductors, is outlined. The aim is to provide a\nframework for studying the interplay of spin relaxation and transport mechanism\nin spintronic devices. Transport inside the (nondegenerate) semiconductor is\ndescribed in terms of a thermoballistic current, in which electrons move\nballistically in the electric field arising from internal and external\nelectrostatic potentials, and are thermalized at randomly distributed\nequilibration points. Spin relaxation is allowed to take place during the\nballistic motion. For arbitrary potential profile and arbitrary values of the\nmomentum and spin relaxation lengths, an integral equation for a spin transport\nfunction determining the spin polarization in the semiconductor is derived. For\nfield-driven transport in a homogeneous semiconductor, the integral equation\ncan be converted into a second-order differential equation that generalizes the\nspin drift-diffusion equation. The spin-polarization in ferromagnet\nsemiconductor structures is obtained by matching the spin-resolved chemical\npotentials at the interfaces, with allowance for spin-selective interface\nresistances. Illustrative examples are considered."
    },
    {
        "anchor": "Active learning and molecular dynamics simulations to find high melting\n  temperature alloys: Active learning (AL) can drastically accelerate materials discovery; its\npower has been shown in various classes of materials and target properties.\nPrior efforts have used machine learning models for the optimal selection of\nphysical experiments or physics-based simulations. However, the latter efforts\nhave been mostly limited to the use of electronic structure calculations and\nproperties that can be obtained at the unit cell level and with negligible\nnoise. We couple AL with molecular dynamics simulations to identify multiple\nprincipal component alloys (MPCAs) with high melting temperatures. Building on\ncloud computing services through nanoHUB, we present a fully autonomous\nworkflow for the efficient exploration of the high dimensional compositional\nspace of MPCAs. We characterize how uncertainties arising from the stochastic\nnature of the simulations and the acquisition functions used to select\nsimulations affect the convergence of the approach. Interestingly, we find that\nrelatively short simulations with significant uncertainties can be used to\nefficiently find the desired alloys as the random forest models used for AL\naverage out fluctuations.",
        "positive": "A size-independent law to describe the alignment of shape-anisotropic\n  objects: A major challenge in the field of nanosciences is the assembly of anisotropic\nnano objects into aligned structures. The way the objects are aligned\ndetermines the physical properties of the final material. In this work, we take\na closer look at the shapes of orientation distributions of aligned anisotropic\nnano and macro objects by examining previously published works. The data shows\nthat the orientation distribution shape of anisotropic objects aligned by\nshearing and other commonly used methods varies size-independently between\nLaplace and Gaussian depending on the distribution width and on the cohesivity\nof the particles."
    },
    {
        "anchor": "Exo-hydrogenated Single Wall Carbon Nanotubes: An extensive first-principles study of fully exo-hydrogenated zigzag (n,0)\nand armchair (n,n) single wall carbon nanotubes (C$_n$H$_n$), polyhedral\nmolecules including cubane, dodecahedrane, and C$_{60}$H$_{60}$ points to\ncrucial differences in the electronic and atomic structures relevant to\nhydrogen storage and device applications. C$_n$H$_n$'s are estimated to be\nstable up to the radius of a (8,8) nanotube, with binding energies proportional\nto 1/R. Attaching a single hydrogen to any nanotube is always exothermic.\nHydrogenation of zigzag nanotubes is found to be more likely than armchair\nnanotubes with similar radius. Our findings may have important implications for\nselective functionalization and finding a way of separating similar radius\nnanotubes from each other.",
        "positive": "Insights into ultrafast Ge-Te bond dynamics in a phase-change\n  superlattice: A long-standing question for avant-grade data storage technology concerns the\nnature of the ultrafast photoinduced phase transformations in the wide class of\nchalcogenide phase-change materials (PCMs). Overall, a comprehensive\nunderstanding of the microstructural evolution and the relevant kinetics\nmechanisms accompanying the out-of-equilibrium phases is still missing. Here,\nafter overheating a phase-change chalcogenide superlattice by an ultrafast\nlaser pulse, we indirectly track the lattice relaxation by time resolved X-ray\nabsorption spectroscopy (tr-XAS) with a sub-ns time resolution. The novel\napproach to the tr-XAS experimental results reported in this work provides an\natomistic insight of the mechanism that takes place during the cooling process,\nmeanwhile a first-principles model mimicking the microscopic distortions\naccounts for a straightforward representation of the observed dynamics.\nFinally, we envisage that our approach can be applied in future studies\naddressing the role of dynamical structural strain in phase-change materials."
    },
    {
        "anchor": "Nanocrystal Growth on Graphene with Various Degrees of Oxidation: We show a general two-step method to grow hydroxide and oxide nanocrystals of\nthe iron family elements (Ni, Co, Fe) on graphene with two degrees of\noxidation. Drastically different nanocrystal growth behaviors were observed on\nlow-oxidation graphene sheets (GS) and highly oxidized graphite oxide (GO) in\nhydrothermal reactions. Small particles pre-coated on GS with few\noxygen-containing surface groups diffused and recrystallized into\nsingle-crystalline nickel hydroxide Ni(OH)2 hexagonal nanoplates or iron oxide\nFe2O3 nanorods with well defined morphologies. In contrast, particles\npre-coated on GO were pinned by the high-concentration oxygen groups and\ndefects on GO without recrystallization into well-defined shapes. Adjusting\nreaction temperature can be combined to further control materials grown on\ngraphene. For materials with weak interactions with graphene, increasing the\nreaction temperature can lead to diffusion and recrystallization of surface\nspecies into larger crystals even on highly oxidized and defective GO. Our\nresults suggest an interesting new approach to controlling the morphology of\nnanomaterials grown on graphene by tuning the surface chemistry of graphene as\nsubstrates for crystal nucleation and growth.",
        "positive": "Atomized Spraying of Liquid Metal Droplets on Desired Substrate Surfaces\n  as a Generalized Way for Ubiquitous Printed Electronics: A direct electronics printing technique through atomized spraying for\npatterning room temperature liquid metal droplets on desired substrate surfaces\nis proposed and experimentally demonstrated for the first time. This method has\ngeneralized purpose and is highly flexible and capable of fabricating\nelectronic components on any desired target objects, with either flat or rough\nsurfaces, made of different materials, or different orientations from 1-D to\n3-D geometrical configurations. With a pre-designed mask, the liquid metal ink\ncan be directly deposited on the substrate to form various specific patterns\nwhich lead to the rapid prototyping of electronic devices. Further, extended\nprinting strategies were also suggested to illustrate the adaptability of the\nmethod such that the natural porous structure can be adopted to offer an\nalternative way of making transparent conductive film with an optical\ntransmittance of 47% and a sheet resistance of 5.167{\\Omega}/O. Different from\nthe former direct writing technology where large surface tension and poor\nadhesion between the liquid metal and the substrate often impede the flexible\nprinting process, the liquid metal here no longer needs to be pre-oxidized to\nguarantee its applicability on target substrates. One critical mechanism was\nfound as that the atomized liquid metal microdroplets can be quickly oxidized\nin the air due to its large specific surface area, resulting in a significant\nincrease of the adhesive capacity and thus firm deposition of the ink to the\nsubstrate. This study established a generalized way for pervasively and\ndirectly printing electronics on various substrates which are expected to be\nsignificant in a wide spectrum of electrical engineering areas."
    },
    {
        "anchor": "Spin crossover self-assembled monolayer of a Co(II) terpyridine\n  derivative functionalized with carboxylic acid groups: The deposition of a monolayer by direct self-assembly from solution of an\nactive spin-crossover (SCO) complex via chemisorption has been achieved\nstarting from the perchlorate salt of Co(II)\nbis(4-(4-carboxyphenyl)-2,2:6,2-terpyridine). MALDI-TOF MS, Raman spectroscopy\nand X-ray photoelectron spectroscopy (XPS) confirm the presence of an intact\nmonolayer of SCO molecules grafted through carboxylate groups to the Ag\nsurface. Three different spectroscopic techniques (Raman, XPS and X-ray\nAbsorption spectroscopy, XAS) evidence a thermal spin transition of such\nmonolayer of molecules. To our knowledge, this is the first example of an\nactive SCO assembly in direct contact with a surface obtained by wet chemistry.",
        "positive": "Effect of intrinsic defects on the thermal conductivity of PbTe from\n  classical molecular dynamics simulations: Despite being the archetypal thermoelectric material, still today some of the\nmost exciting advances in the efficiency of these materials are being achieved\nby tuning the properties of PbTe. Its inherently low lattice thermal\nconductivity can be lowered to its fundamental limit by designing a structure\ncapable of scattering phonons over a wide range of length scales. Intrinsic\ndefects, such as vacancies or grain boundaries, can and do play the role of\nthese scattering sites. Here we assess the effect of these defects by means of\nmolecular dynamics simulations. For this we purposely parametrize a Buckingham\npotential that provides an excellent description of the thermal conductivity of\nthis material over a wide temperature range. Our results show that intrinsic\npoint defects and grain boundaries can reduce the lattice conductivity of PbTe\ndown to a quarter of its bulk value. By studying the size dependence we also\nshow that typical defect concentrations and grain sizes realized in experiments\nnormally correspond to the bulk lattice conductivity of pristine PbTe."
    },
    {
        "anchor": "Electron-hole contribution to the apparent s-d exchange interaction in\n  III-V diluted magnetic semiconductors: Spin splitting of photoelectrons in p-type and electrons in n-type III-V\nMn-based diluted magnetic semiconductors is studied theoretically. It is\ndemonstrated that the unusual sign and magnitude of the apparent s-d exchange\nintegral reported for GaAs:Mn arises from exchange interactions between\nelectrons and holes bound to Mn acceptors. This interaction dominates over the\ncoupling between electrons and Mn spins, so far regarded as the main source of\nspin-dependent phenomena. A reduced magnitude of the apparent s-d exchange\nintegral found in n-type materials is explained by the presence of repulsive\nCoulomb potentials at ionized Mn acceptors and a bottleneck effect.",
        "positive": "Ab-initio studying of spin states of sodium cobaltate Na$_{2/3}$CoO$_2$: Puzzling properties of sodium cobaltates Na${}_x$CoO${}_2$ become an issue of\nnumerous recent theoretical and experimental investigations because of very\nhigh thermopower and intricate phase diagram of this material. Experiments\nindicated Na${}_{2/3}$CoO${}_2$ to have a kagome-like cobalt sublattice, which\nimplies additional complexity of this strongly correlated system. In the\npresent work we have employed the ab-initio GGA+U modeling method to\ninvestigate spin states of Na${}_{2/3}$CoO${}_2$, using an exact crystal cell\nestablished in the experiment. Stability of sodium imprint for concentration\n$x=2/3$ proposed in the publications has been obtained. An AFM-A type magnetic\nordering has been recognized as a ground state. Moreover, a competition between\nlow spin state (LS) and intermediate spin state (IS) has been established to\ndepend on on-site Hubbard $U$ correction parameter. LS state has been\nidentified as a ground state of Na${}_{2/3}$CoO${}_2$."
    },
    {
        "anchor": "A Sampling Strategy in Efficient Potential Energy Surface Mapping for\n  Predicting Atomic Diffusivity in Crystals by Machine Learning: We propose a machine-learning-based (ML-based) method for efficiently\npredicting atomic diffusivity in crystals, in which the potential energy\nsurface (PES) of a diffusion carrier is partially evaluated by first-principles\ncalculations. To preferentially evaluate the region of interest governing the\natomic diffusivity, a statistical PES model based on a Gaussian process\n(GP-PES) is constructed and updated iteratively from known information on\nalready-computed potential energies (PEs). In the proposed method, all local\nenergy minima (stable & metastable sites) and elementary processes of atomic\ndiffusion (atomic jumps) are explored on the predictive mean of the GP-PES. The\nuncertainty of jump frequency in each elementary process is then estimated on\nthe basis of the variance of the GP-PES. The acquisition function determining\nthe next grid point to be computed is designed to reflect the impacts of the\nuncertainties of jump frequencies on the uncertainty of the macroscopic atomic\ndiffusivity. The numerical solution of the master equation is here employed to\nreadily estimate the atomic diffusivity, which enables us to design the\nacquisition function reflecting the centrality of each elementary process.",
        "positive": "Sparse phonon modes of a limit-periodic structure: Limit-periodic structures are well ordered but nonperiodic, and hence have\nnontrivial vibrational modes. We study a ball and spring model with a\nlimit-periodic pattern of spring stiffnesses and identify a set of extended\nmodes with arbitrarily low participation ratios, a situation that appears to be\nunique to limit-periodic systems. The balls that oscillate with large amplitude\nin these modes live on periodic nets with arbitrarily large lattice constants.\nBy studying periodic approximants to the limit-periodic structure, we present\nnumerical evidence for the existence of such modes, and we give a heuristic\nexplanation of their structure."
    },
    {
        "anchor": "Monolayer VTe2: Incommensurate Fermi surface nesting and suppression of\n  charge density waves: We investigated the electronic structure of monolayer VTe2 grown on bilayer\ngraphene by angle-resolved photoemission spectroscopy (ARPES). We found that\nmonolayer VTe2 takes the octahedral 1T structure in contrast to the monoclinic\none in the bulk, as evidenced by the good agreement in the Fermi-surface\ntopology between ARPES results and first-principles band calculations for\noctahedral monolayer 1T-VTe2. We have revealed that monolayer 1T-VTe2 at low\ntemperature is characterized by a metallic state whereas the nesting condition\nis better than that of isostructural monolayer VSe2 which undergoes a CDW\ntransition to insulator at low temperature. The present result suggests an\nimportance of Fermi-surface topology for characterizing the CDW properties of\nmonolayer TMDs.",
        "positive": "Influence of mixing the low-valent transition metal atoms\n  (Y,Y$^*$=Cr,Mn,Fe) on the properties of the quaternary\n  Co$_2$[Y$_{1-x}$Y$^*_x$]Z (Z=Al,Ga,Si,Ge,Sn) Heusler compounds: We complement our study on the doping and disorder in Co$_2$MnZ compounds [I.\nGalanakis \\textit{et al.}, Appl. Phys. Lett. \\textbf{89}, 042502 (2006) and K.\n\\\"Ozdo\\~gan \\textit{et al.}, Phys. Rev. B \\textbf{74}, (2006)] to cover also\nthe quaterarny Co$_2$[Y$_{1-x}$Y$^*_x$]Z compounds with the lower-valent\ntransition metals Y,Y$^*$ being Cr, Mn or Fe and the sp atom Z being one of Al,\nGa, Si, Ge, Sn. This study gives a global overview of the magnetic and\nelectronic properties of these compounds since we vary both Y and Z elements.\nOur results suggest that for realistic applications the most appropriate\ncompounds are the ones belonging to the families Co$_2$[Mn$_{1-x}$Cr$_x$]Z with\n$x>0.5$ irrespectively of the nature of the $sp$ atoms since they combine high\nvalues of majority DOS at the Fermi level due to the presence of Cr, and\nhalf-metallicity with large band-gaps. On the other hand the presence of Fe\nlowers considerably the majority density of states at the Fermi level and when\ncombined with an element belonging to the Si-column, it even can destroy\nhalf-metallicity."
    },
    {
        "anchor": "Structural study of Cu$_{2-x}$Se alloys produced by mechanical alloying: The crystalline structures of superionic high temperature copper selenides\nCu$_{2-x}$Se ($0 \\le x \\le 0.25$) produced by Mechanical Alloying were\ninvestigated using X-ray diffraction (XRD) technique. The measured XRD patterns\nshowed the presence of the peaks corresponding to the crystalline superionic\nhigh temperature $\\alpha$-Cu$_2$Se phase in the as-milled sample, and its\nstructural data were determined by means of a Rietveld refinement procedure.\nAfter a heat treatment in argon at 200$^\\circ$C for 90 h, this phase transforms\nto the superionic high temperature $\\alpha$-Cu$_{1.8}$Se phase, whose\nstructural data where also determined through the Rietveld refinement. In this\nphase, a very low occupation of the trigonal 32(f) sites ($\\sim 3$%) by Cu ions\nis found. In order to explain the evolution of the phases in the samples, two\npossible mechanisms are suggested: the high mobility of Cu ions in superionic\nphases and the intense diffusive processes in the interfacial component of\nsamples produced by Mechanical Alloying.",
        "positive": "Impurity effects on optical response in a finite band electronic system\n  coupled to phonons: The concepts, which have traditionally been useful in understanding the\neffects of the electron--phonon interaction in optical spectroscopy, are based\non insights obtained within the infinite electronic band approximation and no\nlonger apply in finite band metals. Impurity and phonon contributions to\nelectron scattering are not additive and the apparent strength of the coupling\nto the phonon degrees of freedom is substantially reduced with increased\nelastic scattering. The optical mass renormalization changes sign with\nincreasing frequency and the optical scattering rate never reaches its high\nfrequency quasiparticle value which itself is also reduced below its infinite\nband value."
    },
    {
        "anchor": "Space Charge Expansion for Time-resolved Spin-Polarized Electron\n  Spectroscopy: Time resolved spin-polarized electron photoemission spectra are investigated\nas a function of excitation pulse energy for the heterostructures with a single\nstrained layer and with a strained-well superlattice. At an average current\nexceeding 10 nA the emission pulse profiles are modified by the space charge\npulse expansion during the electron transport to detector. The pulse expansion\nenables the separation of electrons that have spent minimum time in the sample.\nFor the superlattice structure these electrons showed maximum polarization\nabove 90 %. Variation in the pulse profiles for the two structures is\ninterpreted as resulting from the difference in the effective NEA values.",
        "positive": "LDA+Usc calculations of phase relations in FeO: Using the LDA+$\\textit{U}_\\text{sc}$ method, we present calculations phase\nrelations of iron monoxides involving five polytypes in multiple spin-state\nconfigurations. The Hubbard parameter $U$ is determined self-consistently\nsimultaneously with the occupation matrix and structures at arbitrary\npressures. The Hubbard parameter strongly depends on pressure, structure, and\nspin state. Comparison with experimental structural data indicates the\nLDA+$\\textit{U}_\\text{sc}$ can predict structure, compression curves, phase\nrelations, and transition pressures very well for the insulating B1 and iB8\nstates. However, it requires additional calculations using the Mermin\nfunctional that includes the electronic entropic contribution to the free\nenergy to obtain an nB8 metallic state and a consistent iB8 to nB8\ninsulator-to-metal transition pressure."
    },
    {
        "anchor": "High-pressure x-ray diffraction study of bulk and nanocrystalline PbMoO4: We studied the effects of high-pressure on the crystalline structure of bulk\nand nanocrystalline scheelite-type PbMoO4. We found that in both cases the\ncompressibility of the materials is highly non-isotropic, being the c-axis the\nmost compressible one. We also observed that the volume compressibility of\nnanocrystals becomes higher that the bulk one at 5 GPa. In addition, at 10.7(8)\nGPa we observed the onset of an structural phase transition in bulk PbMoO4. The\nhigh-pressure phase has a monoclinic structure similar to M-fergusonite. The\ntransition is reversible and not volume change is detected between the low- and\nhigh-pressure phases. No additional structural changes or evidence of\ndecomposition are found up to 21.1 GPa. In contrast nanocrystalline PbMoO4\nremains in the scheelite structure at least up to 16.1 GPa. Finally, the\nequation of state for bulk and nanocrystalline PbMoO4 are also determined.",
        "positive": "A new spin-anisotropic harmonic honeycomb iridate: The physics of Mott insulators underlies diverse phenomena ranging from high\ntemperature superconductivity to exotic magnetism. Although both the electron\nspin and the structure of the local orbitals play a key role in this physics,\nin most systems these are connected only indirectly --- via the Pauli exclusion\nprinciple and the Coulomb interaction. Iridium-based oxides (iridates) open a\nfurther dimension to this problem by introducing strong spin-orbit\ninteractions, such that the Mott physics has a strong orbital character. In the\nlayered honeycomb iridates this is thought to generate highly spin-anisotropic\ninteractions, coupling the spin orientation to a given spatial direction of\nexchange and leading to strongly frustrated magnetism. The potential for new\nphysics emerging from such interactions has driven much scientific excitement,\nmost recently in the search for a new quantum spin liquid, first discussed by\nKitaev \\cite{kitaev_anyons_2006}. Here we report a new iridate structure that\nhas the same local connectivity as the layered honeycomb, but in a\nthree-dimensional framework. The temperature dependence of the magnetic\nsusceptibility exhibits a striking reordering of the magnetic anisotropy,\ngiving evidence for highly spin-anisotropic exchange interactions. Furthermore,\nthe basic structural units of this material suggest the possibility of a new\nfamily of structures, the `harmonic honeycomb' iridates. This compound thus\nprovides a unique and exciting glimpse into the physics of a new class of\nstrongly spin-orbit coupled Mott insulators."
    },
    {
        "anchor": "Thickness-dependent self-polarization-induced intrinsic magnetoelectric\n  effects in La0.67Sr0.33MnO3/PbZr0.52Ti0.48O3 heterostructures: The self-polarization of PbZr0.52Ti0.48O3 thin film is switched by changing\nfilm thickness through the competition between the strain relaxation-induced\nflexoelectric fields and the interfacial effects. Without an applied electric\nfield, this reversal of self-polarization is exploited to control the magnetic\nproperties of La0.67Sr0.33MnO3 by the competition/cooperation between the\ncharge-mediated and the strain-mediated effects. Scanning transmission electron\nmicroscopy, polarized near edge x-ray absorption spectroscopy, and half-integer\ndiffraction measurements are employed to decode this intrinsic magnetoelectric\neffects in La0.67Sr0.33MnO3/PbZr0.52Ti0.48O3 heterostructures. With\nPbZr0.52Ti0.48O3 films < 48 nm, the self-polarization-driven carrier density\nmodulation around La0.67Sr0.33MnO3/PbZr0.52Ti0.48O3 interface and the\nstrain-mediated Mn 3d orbital occupancy work together to enhance magnetism of\n14 unit cells La0.67Sr0.33MnO3 film; with PbZr0.52Ti0.48O3 layers > 48 nm, the\nstrain-induced the change of bond length/angle of MnO6 accompanied with a\nmodified spin configuration are responsible for the decrease in Curie\ntemperature and magnetization of 14 unit cells La0.67Sr0.33MnO3 film.",
        "positive": "Chiral charge density waves induced by Ti-doping in 1T-TaS2: We investigate the Ti-doping effect on the charge density wave (CDW) of\n1T-TaS2 by combining scanning tunneling microscopy (STM) measurements and\nfirst-principle calculations. Although the Ti-doping induced phase evolution\nseems regular with increasing of the doping concentration (x), an unexpected\nchiral CDW phase is observed in the sample with x = 0.08, in which Ti atoms\nalmost fully occupy the central Ta atoms in the CDW clusters. The emergence of\nthe chiral CDW is proposed to be from the doping-enhanced orbital order. Only\nwhen x = 0.08, the possible long-range orbital order can trigger the chiral CDW\nphase. Compared with other 3d-elements doped 1T-TaS2, the Ti-doping retains the\nelectronic flat band and the corresponding CDW phase, which is a prerequisite\nfor the emergence of chirality. We expect that introducing elements with a\nstrong orbital character may induce a chiral charge order in a broad class of\nCDW systems. The present results open up another avenue for further exploring\nthe chiral CDW materials."
    },
    {
        "anchor": "Charge Density Modulation and Defect Ordering in Na$_x$MnBi$_y$ magnetic\n  semimetal: The I-Mn-V antiferromagnet, NaMnBi, develops a very large positive\nmagnetoresistance (MR) up to 10,000% at 2 K and 9 T in crystals showing a\nsemiconductor-to-metal transition (SMT). In the absence of an SMT, a modest\n(20%) MR is achieved. Here, we show that upon cooling below the magnetic\ntransition, a spatial modulation appears giving rise to new Bragg peaks due to\ncharge and defect ordering in a checkerboard pattern, with two kinds of\nmodulation vectors, $q_1$=($\\frac23$, 0, 1) and $q_2$=($\\frac23, \\frac13,\n\\frac12$). This constitutes a superlattice transition ($T_s$) that lowers the\nsymmetry from the high temperature centrosymmetric P4/nmm to the\nnon-centrosymmetric P$\\overline4$m2. In crystals with a large MR, a close to\nroom temperature $T_s$ is observed with $q_1$ appearing first, followed by\n$q_2$. In crystals with low MR however, $T_s$ is much lower and only $q_1$ is\nobserved. The charge modulation and spin fluctuations may both contribute to\nthe enhancement of MR.",
        "positive": "Thermal conductivity of the side ledge in aluminium electrolysis cells:\n  compounds as a function of temperature and grain size: In aluminium electrolysis cells, a ledge of frozen electrolyte is formed,\nattached to the sides of the cell. The control of the side ledge thickness is\nessential in ensuring a reasonable lifetime for the cells. Numerical modelling\nof the side ledge thickness requires an accurate knowledge of the thermal\ntransport properties as a function of temperature. Unfortunately, there is a\nconsiderable lack of experimental data for the large majority of the phases\nconstituting the side ledge. The aim of this work is to provide, for each phase\npossibly present in the side ledge, a formulation of the thermal conductivity\nas a function of both temperature and size. To achieve this, we consider\nreliable physical models linking the density of the lattice vibration energy\nand the phonon mean free path to key parameters: the high temperature limit of\nthe Debye temperature and the Gruneisen constant. These model parameters can be\nobtained by simultaneous fitting of (i) the heat capacity, (ii) the thermal\nexpansion tensor coefficient and (iii) the adiabatic elastic constants, on\nrelevant physical models. Where data is missing, first principles (ab initio)\ncalculations are used to determine directly the model parameters. For compounds\nfor which data is available, the model's predictions are found to be in very\ngood agreement with the reported experimental data."
    },
    {
        "anchor": "Hall effect of epitaxial double-perovskite Sr_2FeMoO_6 thin films: We prepared high epitaxial thin films of the compound Sr_2FeMoO_6 with narrow\nrocking curves by pulsed laser deposition. The diagonal and nondiagonal\nelements of the resistivity tensor were investigated at temperatures from 4 K\nup to room temperature in magnetic fields up to 8 T. An electronlike ordinary\nHall effect and a holelike anomalous Hall contribution are observed. Both\ncoefficients have reversed sign compared to the colossal magnetoresistive\nmanganites. We found at 300 K an ordinary Hall coefficent of -1.87x10^{-10}\nm^3/As, corresponding to a nominal charge carrier density of four electrons per\nformula unit. At low temperature only a small negative magnetoresistance is\nobserved which vanishes at higher temperatures. The temperature coefficient of\nthe resistivity is negative over the whole temperature range. A Kondo like\nbehavior is observed below 30 K while above 100 K variable range hopping like\ntransport occurs.",
        "positive": "Interlayer Breathing and Shear Modes in Few-Layer Black Phosphorus: The interlayer breathing and shear modes in few-layer black phosphorus are\ninvestigated for their symmetry and lattice dynamical properties. The symmetry\ngroups for the even-layer and odd-layer few-layer black phosphorus are utilized\nto determine the irreducible representation and the infrared and Raman activity\nfor the interlayer modes. The valence force field model is applied to calculate\nthe eigenvectorw and frequencies for the interlayer breathing and shear modes,\nwhich are explained using the atomic chain model. The anisotropic puckered\nconfiguration for black phosphorus leads to a highly anisotropic frequency for\nthe two interlayer shear modes. More specifically, the frequency for the shear\nmode in the direction perpendicular to the pucker is less than half of the\nshear mode in the direction parallel with the pucker. We also report a set of\ninterlayer modes having the same frequency for all few-layer black phosphorus\nwith layer number N=3i with integer i, because of their collective vibrational\ndisplacements. The optical activity of the collective modes supports possible\nexperimental identification for these modes."
    },
    {
        "anchor": "The Structural Analysis Possibilities of Reflection High Energy Electron\n  Diffraction: The epitaxial growth of complex oxide thin films provide three avenues to\ngenerate unique properties: the ability to influence the 3-dimensional\nstructure of the film, the presence of a surface, and the generation of an\ninterface. In all three cases, a clear understanding of the resulting atomic\nstructure is desirable. However, determining the full structure of an epitaxial\nthin film (lattice parameters, space group, atomic positions, surface\nreconstructions) on a routine basis is a serious challenge. In this paper we\nhighlight the remarkable information that can be extracted from both the Bragg\nscattering and inelastic multiple scattering events that occur during\nReflection High Energy Electron Diffraction. We review some methods to extract\nstructural information and show how mature techniques used in other fields can\nbe directly applied to the {\\em in-situ} and real-time diffraction images of a\ngrowing film. These collection of techniques give access to both the\nepitaxially influenced 3 dimensional bulk structure of the film, and any\nreconstructions that may happen at the surface.",
        "positive": "Identification of dipolar relaxations in dielectric spectra of\n  mid--voltage cross--linked polyethylene cables: Medium-voltage cross-linked polyethylene (MV-XLPE) cables have an important\nrole in the electrical power distribution system. For this reason, the study of\nXLPE insulation is crucial to improve cable features and lifetime. Although a\nrelaxational analysis using Thermally Stimulated Depolarization Currents (TSDC)\ncan yield a lot of information about XLPE properties, sometimes its results are\ndifficult to interpret. In previous works it was found that the TSDC spectrum\nof cables is dominated by a broad heteropolar peak, that appears just before an\nhomopolar inversion, but the analysis of the cause of the peak was not\nconclusive. We have used a combination of TSDC and Isothermal Depolarization\nCurrents (IDC) techniques to investigate further this issue. In order to\ndiscard spurious effects from the semiconductor interfaces, samples have been\nprepared in certain configurations and preliminary measurements have been done.\nThen, TSDC experiments have been performed using conventional polarization\nbetween 140C and 40C. Also, IDC measurements have been carried out between 90C\nand 110C in 2C steps. The TSDC spectra show the broad peak at 95C. On the other\nhand, IDC show a combination of power and exponential charge currents.\nExponential currents are fitted to a Kohlrausch--Williams--Watts (KWW) model.\nThe parameters obtained present approximately an Arrhenius behavior with\nE_a=1.32eV, tau_0=3.29e-16s, with a KWW parameter beta=0.8. The depolarization\ncurrent calculated from the obtained parameters turns out to match the dominant\npeak of TSDC spectra rather well. From the results and given the partially\nmolten state of the material, we conclude that the most likely cause of the\nexponential IDC and the main TSDC peak is the relaxation of molecular dipoles\nfrom additives incorporated during the manufacturing process."
    },
    {
        "anchor": "Structural and Magnetic Characterization of Large Area, Free-Standing\n  Thin Films of Magnetic Ion Intercalated Dichalcogenides Mn0.25TaS2 and\n  Fe0.25TaS2: Free-standing thin films of magnetic ion intercalated transition metal\ndichalcogenides are produced using ultramicrotoming techniques. Films of\nthicknesses ranging from 30nm to 250nm were achieved and characterized using\ntransmission electron diffraction and X-ray magnetic circular dichroism.\nDiffraction measurements visualize the long range crystallographic ordering of\nthe intercalated ions, while the dichroism measurements directly assess the\norbital contributions to the total magnetic moment. We thus verify the\nunquenched orbital moment in Fe0.25TaS2 and measure the fully quenched orbital\ncontribution in Mn0.25TaS2. Such films can be used in a wide variety of\nultrafast X-ray and electron techniques that benefit from transmission\ngeometries, and allow measurements of ultrafast structural, electronic, and\nmagnetization dynamics in space and time.",
        "positive": "Thermal physics of the lead chalcogenides PbS, PbSe, and PbTe from first\n  principles: The lead chalcogenides represent an important family of functional materials,\nin particular due to the benchmark high-temperature thermoelectric performance\nof PbTe. A number of recent investigations, experimental and theoretical, have\naimed to gather insight into their unique lattice dynamics and electronic\nstructure. However, the majority of first-principles modelling has been\nperformed at fixed temperatures, and there has been no comprehensive and\nsystematic computational study of the effect of temperature on the material\nproperties. We report a comparative lattice-dynamics study of the temperature\ndependence of the properties of PbS, PbSe and PbTe, focussing particularly on\nthose relevant to thermoelectric performance, viz. phonon frequencies, lattice\nthermal conductivity, and electronic band structure. Calculations are performed\nwithin the quasi-harmonic approximation, with the inclusion of phonon-phonon\ninteractions from many-body perturbation theory, which are used to compute\nphonon lifetimes and predict the lattice thermal conductivity. The results are\ncritically compared against experimental data and other calculations, and add\nnew insight to on-going research on the PbX compounds in relation to the\noff-centring of Pb at high temperatures, which is shown to be related to phonon\nsoftening. The agreement with experiment suggests that this method could serve\nas a straightforward, powerful and generally-applicable means of investigating\nthe temperature dependence of material properties from first principles."
    },
    {
        "anchor": "A two-dimensional hexagonal sheet of TiO$_2$: We report on the ab initio discovery of a novel putative ground state for\nquasi two-dimensional TiO$_2$ through a structural search using the minima\nhopping method with an artificial neural network potential. The structure is\nbased on a honeycomb lattice and is energetically lower than the experimentally\nreported lepidocrocite sheet by 7~meV/atom, and merely 13~meV/atom higher in\nenergy than the ground state rutile bulk structure. According to our\ncalculations, the hexagonal sheet is stable against mechanical stress, it is\nchemically inert and can be deposited on various substrates without disrupting\nthe structure. Its properties differ significantly from all known TiO$_2$ bulk\nphases with a large gap of 5.05~eV that can be tuned through strain\nengineering.",
        "positive": "Intrinsic Defects and Electronic Conductivity of TaON: First-Principles\n  Insights: As a compound in between the tantalum oxide and nitride, the tantalum\noxynitride TaON is expected to combine their advantages and act as an efficient\nvisible-light-driven photocatalyst. In this letter, using hybrid functional\ncalculations we show that TaON has different defect properties from the binary\ntantalum oxide and nitride: (i) instead of O or N vacancies or Ta\ninterstitials, the $O_N$ antisite is the dominant defect, which determines its\nintrinsic n-type conductivity and the p-type doping difficulty; (ii) the $O_N$\nantisite has a shallower donor level than O or N vacancies, with a delocalized\ndistribution composed mainly of the Ta $5d$ orbitals, which gives rise to\nbetter electronic conductivity in the oxynitride than in the oxide and nitride.\nThe phase stability analysis reveals that the easy oxidation of TaON is\ninevitable under O rich conditions, and a relatively O poor condition is\nrequired to synthesize stoichiometric TaON samples."
    },
    {
        "anchor": "Transport Properties of Ni, Co, Fe, Mn Doped Cu0.01Bi2Te2.7Se0.3 for\n  Thermoelectric Device Applications: Bi2Te3 based thermoelectric devices typically use a nickel layer as a\ndiffusion barrier to block the diffusion of solder or copper atoms from the\nelectrode into the thermoelectric material. Previous studies have shown\ndegradation in the efficiency of these thermoelectric devices may be due to the\ndiffusion of the barrier layer into the thermoelectric material. In this work\nNi, Co, Fe, and Mn are intentionally doped into Cu0.01Bi2Te2.7Se0.3 in order to\nunderstand their effects on the thermoelectric material. Thermoelectric\ntransport properties including the Seebeck coefficient, thermal conductivity,\nelectrical resistivity, carrier concentration, and carrier mobility of\nCu0.01Bi2Te2.7Se0.3 doped with 2 atomic percent M (M=Ni, Co, Fe, Mn) as\nCu0.01Bi2Te2.7Se0.3M0.02, are studied in a temperature range of 5-525 K.",
        "positive": "Assessing the accuracy of quantum Monte Carlo and density functional\n  theory for energetics of small water clusters: We present a detailed study of the energetics of water clusters (H$_2$O)$_n$\nwith $n \\le 6$, comparing diffusion Monte Carlo (DMC) and approximate density\nfunctional theory (DFT) with well converged coupled-cluster benchmarks. We use\nthe many-body decomposition of the total energy to classify the errors of DMC\nand DFT into 1-body, 2-body and beyond-2-body components. Using both\nequilibrium cluster configurations and thermal ensembles of configurations, we\nfind DMC to be uniformly much more accurate than DFT, partly because some of\nthe approximate functionals give poor 1-body distortion energies. Even when\nthese are corrected, DFT remains considerably less accurate than DMC. When both\n1- and 2-body errors of DFT are corrected, some functionals compete in accuracy\nwith DMC; however, other functionals remain worse, showing that they suffer\nfrom significant beyond-2-body errors. Combining the evidence presented here\nwith the recently demonstrated high accuracy of DMC for ice structures, we\nsuggest how DMC can now be used to provide benchmarks for larger clusters and\nfor bulk liquid water."
    },
    {
        "anchor": "On the Hardness of a New Boron Phase, Orthorhombic \u03b3-B28: Measurements of the hardness of a new high-pressure boron phase, orthorhombic\n{\\gamma}-B28, are reported. According to the data obtained, {\\gamma}-B28 has\nthe highest hardness (~50 GPa) of all known crystalline modifications of boron.",
        "positive": "Lattice gas models of coherent strained epitaxy: The harmonic Frenkel-Kontorova model is used to illustrate with an exactly\nsolvable example a general technique of mapping a coherently strained epitaxial\nsystem with continuous atomic displacements onto a lattice gas model (LGM) with\nonly discrete variables. The misfit strain of the original model is transformed\ninto cluster interatomic interactions of the LGM. The clusters are contiguous\natomic chains of all lengths but the interaction strength for long chains is\nexponentially small. This makes possible the application of efficient Monte\nCarlo techniques developed for discrete variables both in kinetic and\nequilibrium simulations. The formalism developed can be applied to 1D as well\nas to 2D systems. As an illustrative example we consider the problem of\nself-organization of 1D size calibrated clusters on the steps of the vicinal\nsurfaces."
    },
    {
        "anchor": "Berry phase theory of Dzyaloshinskii-Moriya interaction and spin-orbit\n  torques: Recent experiments on current-induced domain wall motion in chiral magnets\nsuggest important contributions both from spin-orbit torques (SOTs) and from\nthe Dzyaloshinskii-Moriya interaction (DMI). We derive a Berry phase expression\nfor the DMI and show that within this Berry phase theory DMI and SOTs are\nintimately related, in a way formally analogous to the relation between orbital\nmagnetization (OM) and anomalous Hall effect (AHE). We introduce the concept of\nthe \\textit{twist torque moment}, which probes the internal twist of wave\npackets in chiral magnets in a similar way like the orbital moment probes the\nwave packet's internal self rotation. We propose to interpret the Berry phase\ntheory of DMI as a theory of \\textit{spiralization} in analogy to the modern\ntheory of OM. We show that the twist torque moment and the spiralization\ntogether give rise to a Berry phase governing the response of the SOT to\nthermal gradients, in analogy to the intrinsic anomalous Nernst effect. The\nBerry phase theory of DMI is computationally very efficient because it only\nneeds the electronic structure of the collinear magnetic system as input. As an\napplication of the formalism we compute the DMI in Pt/Co, Pt/Co/O and Pt/Co/Al\nmagnetic trilayers and show that the DMI is highly anisotropic in these\nsystems.",
        "positive": "Heterogeneous local plastic deformation of interstitial free steel\n  revealed using in-situ tensile testing and high angular resolution electron\n  backscatter diffraction: Metals are important structural materials for transport and the built\nenvironment. Low carbon steels can fail through strain localisation due to the\nrole of interstitial solute atoms (such as carbon and nitrogen) interacting\nwith mobile dislocations, and this gives rise to the Portevin-Le Chatelier\neffect and the formation of Luders bands. In this work, we use in-situ tensile\ntesting and observation with High Angular Resolution Electron Back Scatter\nDiffraction (HR-EBSD) to explore deformation patterning in two Interstitial\nFree (IF) steel samples. One of these steels was heat treated to trigger strain\nlocalisation and Luders bands whilst the other was heat treated to homogenise\nplastic strain and limit flow localisation. Our work reveals that flow\nlocalisation at the macroscopic scale is closely correlated with differences in\nthe storage of dislocations at the microscale through analysis of the HR-EBSD\nderived fields of stored Geometrically Necessary Dislocations (GNDs).\nHomogeneous plastic flow correlates with more 'Face Centred Cubic (FCC)-like'\ndeformation patterning in these Body Centred Cubic (BCC) materials, where work\nhardening is correlated with the association of dislocation networks which\ninteract with triple junctions and grain boundaries, and our in-situ tests\nenable us to see how these fields develop. Our findings enable the modification\nof steel processing routes, and micromechanical models, based upon information\nobtained from these in-situ tests."
    },
    {
        "anchor": "Excitonic effects in energy loss spectra of freestanding graphene: In this work we perform electron energy-loss spectroscopy (EELS) of\nfreestanding graphene with high energy and momentum resolution to disentangle\nthe quasielastic scattering from the excitation gap of Dirac electrons close to\nthe optical limit. We show the importance of many-body effects on electronic\nexcitations at finite transferred momentum by comparing measured EELS with ab\ninitio calculations at increasing levels of theory. Quasi-particle corrections\nand excitonic effects are addressed within the GW approximation and\nBethe-Salpeter equation, respectively. Both effects are essential in the\ndescription of the EEL spectra to obtain a quantitative agreement with\nexperiments, with the position, dispersion, and shape of both the excitation\ngap and the $\\pi$ plasmon being significantly affected by excitonic effects.",
        "positive": "On the anisotropies of magnetization and electronic transport of\n  magnetic Weyl semimetal Co3Sn2S2: Co3Sn2S2, a quasi-two-dimensional system with kagome lattice, has been found\nas a magnetic Weyl semimetal recently. In this work, the anisotropies of\nmagnetization and transport properties of Co3Sn2S2 were investigated. The high\nfield measurements reveal a giant magnetocrystalline anisotropy with an\nout-of-plane saturation field of 0.9 kOe and an in-plane saturation field of\n230 kOe at 2 K, showing a magnetocrystalline anisotropy coefficient Ku up to\n8.3 * 10^5 J m-3, which indicates that it is extremely difficult to align the\nsmall moment of 0.29 {\\mu}B/Co on the kagome lattice from c axis to ab plane.\nThe out-of-plane angular dependences of Hall conductivity further reveal strong\nanisotropies in Berry curvature and ferromagnetism, and the vector directions\nof both are always parallel with each other. For in-plane situation, the\nlongitudinal and transverse measurements for both I parallel a and I\nperpendicular a cases show that the transport on the kagome lattice is\nisotropic. These results provide essential understanding on the magnetization\nand transport behaviors for the magnetic Weyl semimetal Co3Sn2S2."
    },
    {
        "anchor": "Thermal conductivity of Magnesium Telluride (MgTe) -- A first principles\n  study: In this work, we report thermal conductivity(k) of magnesium telluride (MgTe)\nwith various crystallographic phases such as rocksalt, zincblende, wurtzite and\nnickel arsenic (NiAs) using density functional theory and Boltzmann transport\nequation. Our first principles calculations results show the low thermal\nconductivity of MgTe with kNiAs < krocksalt < kwurtzite < kzincblende. We\nsystematically investigated the phonon group velocity, phonon scattering rate\nand mode contributed thermal conductivity of transverse acoustic (TA),\nlongitudinal acoustic (LA) and optical phonons. Our first principles\ncalculations shows that ultra-low thermal conductivity of 2.645 Wm-1K-1 for\nNiAs phase is due to the dominant scattering of TA and LA phonons by low\nfrequency optical phonons. We also analyzed the length dependence thermal\nconductivity of MgTe at nanometer length-scales. At nanometer length scales\nsuch as 50 nm for NiAs phase, room temperature thermal conductivity of less\nthan 1.4 Wm-1K-1 shows a promising nature of MgTe for thermoelectric\napplications.",
        "positive": "Correlating elasticity and crack formation: For solving the longstanding materials science problem of correlating elastic\nproperties of a solid material to the formation of cracks we present a new\ngeneral concept. This concept is applied to the technologically most important\ncracks of loading mode I for which we establish exact correlations by\nintroducing a localization length as a new material parameter. We study two\nlimiting cases of crack formation making use of analytic models determining the\nmaterial and direction dependent parameters by comparison to {\\em ab initio}\ndensity functional results. This is done for a variety of real materials in\norder to test our approach for different types of bonding. For the most\ninteresting ideal brittle cleavage we find that the localization length is\n-within a reasonable approximation- of constant value, which results in a\nsimple relation for the critical stress, presumably being useful for materials\nengineering. Our results confirm that the proposed general concept results in\nmeaningful physical models which -for the first time- allow a rigorous and\nsimple correlation between elastic and mechanical properties."
    },
    {
        "anchor": "Network efficiency of spatial systems with fractal morphology: a\n  geometric graphs approach: The functional features of spatial networks depend upon a non-trivial\nrelationship between the topological and physical structure. Here, we explore\nthat relationship for spatial networks with radial symmetry and disordered\nfractal morphology. Under a geometric graphs approach, we quantify the\neffectiveness of the exchange of information in the system from center to\nperimeter and over the entire network structure. We mainly consider two\nparadigmatic models of disordered fractal formation, the Ballistic Aggregation\nand Diffusion-Limited Aggregation models, and complementary, the Viscek and\nHexaflake fractals, and Kagome and Hexagonal lattices. First, we show that\ncomplex tree morphologies provide important advantages over regular\nconfigurations, such as an invariant structural cost for different fractal\ndimensions. Furthermore, although these systems are known to be scale-free in\nspace, they have bounded degree distributions for different values of an\neuclidean connectivity parameter and, therefore, do not represent ordinary\nscale-free networks. Finally, compared to regular structures, fractal trees are\nfragile and overall inefficient as expected, however, we show that this\nefficiency can become similar to that of a robust hexagonal lattice, at a\nsimilar cost, by just considering a very short euclidean connectivity beyond\nfirst neighbors.",
        "positive": "Numerical Simulation of The Mechanical Properties of Nanoscale Metal\n  Clusters Using The Atomistic-Continuum Mechanics Method: A novel atomistic-continuum method (ACM) based on finite element method (FEM)\nis proposed to numerically simulate the nano-scaled Poisson's ratio and Young's\nmodulus effect of Lithium (Li) body-centered cubic (BCC) structure. The\npotential energy between Li atoms is described by the Morse potential function\n[1]. The pre-force effect will be discussed due to the different Li lattice\nlength between experimental lattice constant and diatom distance from Morse\nfunction. Moreover, the size effect of the nano-scaled Li cluster will be\nintroduced."
    },
    {
        "anchor": "Mechanism of photo-excited precession of magnetization in (Ga,Mn)As on\n  the basis of time-resolved spectroscopy: Aiming at studying the mechanism of photo-excited precession of magnetization\nin ferromagnetic (Ga,Mn)As, magneto-optical (MO) and differential reflectivity\n(DR) temporal profiles are studied at relatively long and ultra-short time\nscales for samples with different Mn contents (x=0.01-0.11). As to the\noscillatory MO profiles observed in the long time scale, simulation based on\nthe LLG equation combined with two different MO effects confirms\nphoto-inducement of the perpendicular anisotropy component p-Heff. As for the\nprofiles observed in the ultra-short time scale, they are consistently\nexplained in terms of the dynamics of photo-generated carriers, but not by the\nsudden reduction in magnetization. With those experimental results and\nanalyses, new mechanism which accounts for the photo-induced p-Heff is\naddressed; photo-ionization like excitation of Mn(II). Namely, Mn(II) is\nexcited into Mn(III) and e . It is discussed that such excitation tips magnetic\nanisotropy toward the out-of-plane direction through the inducement of orbital\nangular momentum and the gradient dMn(II*)/dz. Validity of the proposed\nmechanism is examined by estimating the efficiency of excitation on the basis\nof the Lambert-Beer law and the experimental p-Heff values, through which the\nefficiency of 1-10 ppm with the nominal optical cross section of around 5 x\n10^12 m^2 are obtained.",
        "positive": "Electric field control of interfacial Dzyaloshinskii-Moriya interaction\n  in Pt/Co/AlO$_x$ thin films: We studied electric field modification of magnetic properties in a\nPt/Co/AlO$_x$ trilayer via magneto-optical Kerr microscopy. We observed the\nspontaneous formation of labyrinthine magnetic domain structure due to\nthermally activated domain nucleation and propagation under zero applied\nmagnetic field. A variation of the period of the labyrinthine structure under\nelectric field is observed as well as saturation magnetization and magnetic\nanisotropy variations. Using an analytical formula of the stripe equilibrium\nwidth we estimate the variation of the interfacial Dzyaloshinskii-Moriya\ninteraction under electric field as function of the exchange stiffness\nconstant."
    },
    {
        "anchor": "Printed Graphene Circuits: we have fabricated transparent electronic devices based on graphene materials\nwith thickness down to one single atomic layer by the transfer printing method.\nThe resulting printed graphene devices retain high field effect mobility and\nhave low contact resistance. The results show that the transfer printing method\nis capable of high-quality transfer of graphene materials from silicon dioxide\nsubstrates, and the method thus will have wide applications in manipulating and\ndelivering graphene materials to desired substrate and device geometries. Since\nthe method is purely additive, it exposes graphene (or other functional\nmaterials) to no chemical preparation or lithographic steps, providing greater\nexperimental control over device environment for reproducibility and for\nstudies of fundamental transport mechanisms. Finally, the transport properties\nof the graphene devices on the PET substrate demonstrate the non-universality\nof minimum conductivity and the incompleteness of the current transport theory.",
        "positive": "Symmetry analysis of strain, electric and magnetic fields in the\n  $\\text{Bi}_2\\text{Se}_3$-class of topological insulators: Based on group theoretical arguments we derive the most general Hamiltonian\nfor the $\\text{Bi}_2\\text{Se}_3$-class of materials including terms to third\norder in the wave vector, first order in electric and magnetic fields, first\norder in strain and first order in both strain and wave vector. We determine\nanalytically the effects of strain on the electronic structure of\n$\\text{Bi}_2\\text{Se}_3$. For the most experimentally relevant surface\ntermination we analytically derive the surface state spectrum, revealing an\nanisotropic Dirac cone with elliptical constant energy counturs giving rise to\ndifferent velocities in different in-plane directions. The spin-momentum\nlocking of strained $\\text{Bi}_2\\text{Se}_3$ is shown to be modified and for\nsome strain configurations we see a non-zero spin component perpendicular to\nthe surface. Hence, strain control can be used to manipulate the spin degree of\nfreedom via the spin-orbit coupling. We show that for a thin film of\n$\\text{Bi}_2\\text{Se}_3$ the surface state band gap induced by coupling between\nthe opposite surfaces changes opposite to the bulk band gap under strain.\nTuning the surface state band gap by strain, gives new possibilities for the\nexperimental investigation of the thickness dependent gap and optimization of\noptical properties relevant for, e.g., photodetector and energy harvesting\napplications. We finally derive analytical expressions for the effective mass\ntensor of the Bi$_2$Se$_3$ class of materials as a function of strain and\nelectric field."
    },
    {
        "anchor": "Universality in the Photophysics of pi-Conjugated Polymers and\n  Single-Walled Carbon Nanotubes: We describe both pi-conjugated polymers and semiconducting single-walled\ncarbon nanotubes because of the remarkable similarities in their behavior under\nphotoexcitation. The common themes between these two seemingly different\nclasses of materials are pi-conjugation, quasi one-dimensionality, and strong\nCoulomb interactions. Theoretical understanding of both systems requires going\nbeyond traditional band theory. We present our current understanding of the\nelectronic structures and excited state absorptions in both systems within a\ncommon theoretical model. Our aim is to give physical interpretations of\nexperiments that have been performed and to give guidance to future\nexperimental work.",
        "positive": "Spin Channels in Functionalized Graphene Nanoribbons: We characterize the transport properties of functionalized graphene\nnanoribbons using extensive first-principles calculations based on density\nfunctional theory (DFT) that encompass both monovalent and divalent ligands,\nhydrogenated defects and vacancies. We find that the edge metallic states are\npreserved under a variety of chemical environments, while bulk conducting\nchannels can be easily destroyed by either hydrogenation or ion or electron\nbeams, resulting in devices that can exhibit spin conductance polarization\nclose to unity."
    },
    {
        "anchor": "Understanding angle-resolved polarized Raman scattering from black\n  phosphorus at normal and oblique laser incidences: The selection rule for angle-resolved polarized Raman (ARPR) intensity of\nphonons from standard group-theoretical method in isotropic materials would\nbreak down in anisotropic layered materials (ALMs) due to birefringence and\nlinear dichroism effects. The two effects result in depth-dependent\npolarization and intensity of incident laser and scattered signal inside ALMs\nand thus make a challenge to predict ARPR intensity at any laser incidence\ndirection. Herein, taking in-plane anisotropic black phosphorus as a prototype,\nwe developed a so-called birefringence-linear-dichroism (BLD) model to\nquantitatively understand its ARPR intensity at both normal and oblique laser\nincidences by the same set of real Raman tensors for certain laser excitation.\nNo fitting parameter is needed, once the birefringence and linear dichroism\neffects are considered with the complex refractive indexes. An approach was\nproposed to experimentally determine real Raman tensor and complex refractive\nindexes, respectively, from the relative Raman intensity along its principle\naxes and incident-angle resolved reflectivity by Fresnel$'$s law. The results\nsuggest that the previously reported ARPR intensity of ultrathin ALM flakes\ndeposited on a multilayered substrate at normal laser incidence can be also\nunderstood based on the BLD model by considering the depth-dependent\npolarization and intensity of incident laser and scattered Raman signal induced\nby both birefringence and linear dichroism effects within ALM flakes and the\ninterference effects in the multilayered structures, which are dependent on the\nexcitation wavelength, thickness of ALM flakes and dielectric layers of the\nsubstrate. This work can be generally applicable to any opaque anisotropic\ncrystals, offering a promising route to predict and manipulate the polarized\nbehaviors of related phonons.",
        "positive": "Surface plasmons in metallic structures: Since the concept of a surface collective excitation was first introduced by\nRitchie, surface plasmons have played a significant role in a variety of areas\nof fundamental and applied research, from surface dynamics to surface-plasmon\nmicroscopy, surface-plasmon resonance technology, and a wide range of photonic\napplications. Here we review the basic concepts underlying the existence of\nsurface plasmons in metallic structures, and introduce a new low-energy surface\ncollective excitation that has been recently predicted to exist."
    },
    {
        "anchor": "Intrinsic and extrinsic contributions to spin scattering in Pt: We utilize nanoscale spin valves with Pt spacer layers to characterize spin\nscattering in Pt. Analysis of the spin lifetime determined from our\nmeasurements indicates that the extrinsic Elliot-Yafet spin scattering is\ndominant at room temperature, while the intrinsic Dyakonov-Perel mechanism\ndominates at cryogenic temperatures. The significance of the latter is\nsupported by the suppression of spin relaxation in Pt layers interfaced with a\nferromagnet, likely caused by the competition between the effective exchange\nand spin-orbit fields.",
        "positive": "Gamma relaxation in bulk metallic glasses: Studying the primary {\\alpha}- and secondary {\\beta}-relaxation process has\ncontributed significantly to the understanding of the structure and rheology of\nmetallic glasses. In this letter, we report on a third relaxation mechanism\nindicated by a maximum in the loss modulus at low temperatures, which we term\n{\\gamma}-relaxation. Contrary to the {\\alpha}- and {\\beta}-relaxation\nmechanisms, this irreversible, low energy excitation causes a macroscopic\nrejuvenation, which we assign to non-affine atomic rearrangements in the matrix\nthat are driven by thermal stresses during cooling. Observed in three different\nglassy alloys, the low temperature relaxation is identified as a general\nprocess in metallic glasses."
    },
    {
        "anchor": "Thermoelectric properties of lead chalcogenide core-shell nanostructures: We present the full thermoelectric characterization of nanostructured bulk\nPbTe and PbTe-PbSe samples fabricated from colloidal core-shell nanoparticles\nfollowed by spark plasma sintering. An unusually large thermopower is found in\nboth materials, and the possibility of energy filtering as opposed to grain\nboundary scattering as an explanation is discussed. A decreased Debye\ntemperature and an increased molar specific heat are in accordance with recent\npredictions for nanostructured materials. On the basis of these results we\npropose suitable core-shell material combinations for future thermoelectric\nmaterials of large electric conductivities in combination with an increased\nthermopower by energy filtering.",
        "positive": "An Empirical Tight-Binding Model for Titanium Phase Transformations: For a previously published study of the titanium hcp (alpha) to omega (omega)\ntransformation, a tight-binding model was developed for titanium that\naccurately reproduces the structural energies and electron eigenvalues from\nall-electron density-functional calculations. We use a fitting method that\nmatches the correctly symmetrized wavefuctions of the tight-binding model to\nthose of the density-functional calculations at high symmetry points. The\nstructural energies, elastic constants, phonon spectra, and point-defect\nenergies predicted by our tight-binding model agree with density-functional\ncalculations and experiment. In addition, a modification to the functional form\nis implemented to overcome the \"collapse problem\" of tight-binding, necessary\nfor phase transformation studies and molecular dynamics simulations. The\naccuracy, transferability and efficiency of the model makes it particularly\nwell suited to understanding structural transformations in titanium."
    },
    {
        "anchor": "Time- and momentum-resolved photoemission studies using time-of-flight\n  momentum microscopy at a free-electron laser: Time-resolved photoemission with ultrafast pump and probe pulses is an\nemerging technique with wide application potential. Real-time recording of\nnon-equilibrium electronic processes, transient states in chemical reactions or\nthe interplay of electronic and structural dynamics offers fascinating\nopportunities for future research. Combining valence-band and core-level\nspectroscopy with photoelectron diffraction for electronic, chemical and\nstructural analysis requires few 10 fs soft X-ray pulses with some 10 meV\nspectral resolution, which are currently available at high repetition rate\nfree-electron lasers. The PG2 beamline at FLASH (DESY, Hamburg) provides a high\npulse rate of 5000 pulses/s, 60 fs pulse duration and 40 meV bandwidth in an\nenergy range of 25-830 eV with a photon beam size down to 50 microns in\ndiameter. We have constructed and optimized a versatile setup commissioned at\nFLASH/PG2 that combines FEL capabilities together with a multidimensional\nrecording scheme for photoemission studies. We use a full-field imaging\nmomentum microscope with time-of-flight energy recording as the detector for\nmapping of 3D band structures in ($k_x$, $k_y$, $E$) parameter space with\nunprecedented efficiency. Our instrument can image full surface Brillouin zones\nwith up to 7 {\\AA} $^{-1}$ diameter in a binding-energy range of several eV,\nresolving about $2.5\\times10^5$ data voxels. As an example, we present results\nfor the ultrafast excited state dynamics in the model van der Waals\nsemiconductor WSe$_2$.",
        "positive": "Designing optoelectronic properties by on-surface synthesis: formation\n  and electronic structure of an iron-terpyridine macromolecular complex: Supramolecular chemistry protocols applied on surfaces offer compelling\navenues for atomic scale control over organic-inorganic interface structures.\nIn this approach, adsorbate-surface interactions and two-dimensional\nconfinement can lead to morphologies and properties that differ dramatically\nfrom those achieved via conventional synthetic approaches. Here, we describe\nthe bottom-up, on-surface synthesis of one-dimensional coordination\nnanostructures based on an iron (Fe)-terpyridine (tpy) interaction borrowed\nfrom functional metal-organic complexes used in photovoltaic and catalytic\napplications. Thermally activated diffusion of sequentially deposited ligands\nand metal atoms, and intra-ligand conformational changes, lead to Fe-tpy\ncoordination and formation of these nanochains. Low-temperature Scanning\nTunneling Microscopy and Density Functional Theory were used to elucidate the\natomic-scale morphology of the system, providing evidence of a linear tri-Fe\nlinkage between facing, coplanar tpy groups. Scanning Tunneling Spectroscopy\nreveals highest occupied orbitals with dominant contributions from states\nlocated at the Fe node, and ligand states that mostly contribute to the lowest\nunoccupied orbitals. This electronic structure yields potential for hosting\nphoto-induced metal-to-ligand charge transfer in the visible/near-infrared. The\nformation of this unusual tpy/tri-Fe/tpy coordination motif has not been\nobserved for wet chemistry synthesis methods, and is mediated by the bottom-up\non-surface approach used here."
    },
    {
        "anchor": "Predictive Model of Hydrogen Trapping and Bubbling in Nanovoids in BCC\n  Metals: Interplay between hydrogen and nanovoids, despite long-recognized as a\ncentral aspect in hydrogen-induced damages in structural materials, remains\npoorly understood. Focusing on tungsten as a model BCC system, the present\nstudy, for the first time, explicitly demonstrated sequential adsorption of\nhydrogen adatoms on Wigner-Seitz squares of nanovoids with distinct energy\nlevels. Interaction between hydrogen adatoms on the nanovoid surface is shown\nto be dominated by pairwise power law repulsion. A predictive model was\nestablished for quantitative prediction of configurations and energetics of\nhydrogen adatoms in nanovoids. This model, further combined with equation of\nstates of hydrogen gas, enables prediction of hydrogen molecule formation in\nnanovoids. Multiscale simulations based on the predictive model were performed,\nshowing excellent agreement with experiments. This work clarifies fundamental\nphysics and provides full-scale predictive model for hydrogen trapping and\nbubbling in nanovoids, offering long-sought mechanistic insights crucial for\nunderstanding hydrogen-induced damages in structural materials.",
        "positive": "Multiferroic properties of oxygen functionalized magnetic i-MXene: Two dimensional multiferroics inherit prominent physical properties from both\nlow dimensional materials and magnetoelectric materials, and can go beyond\ntheir three dimensional counterparts for their unique structures. Here, based\non density functional theory calculations, a MXene derivative, i.e., i-MXene\n(Ta$_{2/3}$Fe$_{1/3}$)$_2$CO$_2$, is predicted to be a type-I multiferroic\nmaterial. Originated from the reliable $5d^0$ rule, its ferroelectricity is\nrobust, with a moderate polarization up to $\\sim12.33$ $\\mu$C/cm$^2$ along the\na-axis, which can be easily switched and may persist above room temperature.\nIts magnetic ground state is layered antiferromagnetism. Although it is a\ntype-I multiferroic material, its N\\'eel temperature can be significantly tuned\nby the paraelectric-ferroelectric transition, manifesting a kind of intrinsic\nmagnetoelectric coupling. Such magnetoelectric effect is originated from the\nconventional magnetostriction, but unexpectedly magnified by the exchange\nfrustration. Our work not only reveals a nontrivial magnetoelectric mechanism,\nbut also provides a strategy to search for more multiferroics in the two\ndimensional limit."
    },
    {
        "anchor": "Thermodynamic and thermoelectric properties of (Ga,Mn)As and related\n  compounds: Various experimental results providing information on thermodynamic density\nof states in (Ga,Mn)As are analyzed theoretically assuming that holes occupy\nGaAs-like valence bands. Allowing for Gaussian fluctuations of magnetization,\nthe employed model describes correctly a critical behavior of magnetic specific\nheat found experimentally in (Ga,Mn)As near the Curie temperature T_C [S.\nYuldashev et al., Appl. Phys. Express 3, 073005 (2010)]. The magnitudes of room\ntemperature thermoelectric power, as measured for GaAs:Be and (Ga,Mn)As [M. A.\nMayer et al., Phys. Rev. B 81, 045205 (2010)], are consistent with the model\nfor the expected energy dependencies of the hole mobility. The same approach\ndescribes also temperature variations of conductance specific to the\nAnderson-Mott localization, found for various dimensionality (Ga,Mn)As\nnanostructures at subkelvin temperatures [D. Neumaier et al., Phys. Rev. Lett.\n103, 087203 (2009)]. We conclude that the examined phenomena do not provide\nevidence for an enhancement of density of states by the presence of an impurity\nband at the Fermi energy in ferromagnetic (Ga,Mn)As. Furthermore, we provide\nfor (Ga,Mn)As expected values of both electronic specific heat at low\ntemperatures T << T_C and magnetization as a function of the magnetic field at\nT_C.",
        "positive": "Static and dynamic friction of hierarchical surfaces: Hierarchical structures are very common in Nature, but only recently have\nthey been systematically studied in materials physics, in order to understand\nthe specific effects they can have on the mechanical properties of various\nsystems. Structural hierarchy provides a way to tune and optimize macroscopic\nmechanical properties starting from simple base constituents, and new materials\nare nowadays designed exploiting this possibility. This can be also true in the\nfield of tribology. In this paper, we study the effect of hierarchical\npatterned surfaces on the static and dynamic friction coefficients of an\nelastic material. Our results are obtained by means of numerical simulations\nusing a 1-D spring-block model, which has previously been used to investigate\nvarious aspects of friction. Despite the simplicity of the model, we highlight\nsome possible mechanisms that explain how hierarchical structures can\nsignificantly modify the friction coefficients of a material, providing a means\nto achieve tunability."
    },
    {
        "anchor": "Semitransparent anisotropic and spin Hall magnetoresistance sensor\n  enabled by spin-orbit toque biasing: We demonstrate an ultrathin and semitransparent anisotropic and spin Hall\nmagnetoresistance sensor based on NiFe/Pt heterostructure. The use of\nspin-orbit torque effective field for transverse biasing allows to reduce the\ntotal thickness of the sensors down to 3 - 4 nm and thereby leading to the\nsemitransparency. Despite the extremely simple design, the spin-orbit torque\neffective field biased NiFe/Pt sensor exhibits level of linearity and\nsensitivity comparable to those of sensors using more complex linearization\nschemes. In a proof-of-concept design using a full Wheatstone bridge comprising\nof four sensing elements, we obtained a sensitivity up to 202.9 m{\\Omega}/Oe,\nlinearity error below 5%, and a detection limit down to 20 nT. The\ntransmittance of the sensor is over 50% in the visible range.",
        "positive": "An Electrohydrodynamics Model for Non-equilibrium Electron and Phonon\n  Transport in Metal Films after Ultra-short Pulse Laser Heating: The electrons and phonons in metal films after ultra-short pulse laser\nheating are in highly non-equilibrium states not only between the electron\nsub-system and the phonon sub-system but also within the electron sub-system.\nAn electrohydrodynamics model consisting of the balance equations of electron\ndensity, energy density of electrons, and energy density of phonons is derived\nfrom the coupled non-equilibrium electron and phonon Boltzmann transport\nequations to study the nonlinear transport phenomena, such as the electron\ndensity fluctuation and the transient electrical current in metal films, after\nultra-short pulse laser heating. The time-dependent temperature distributions\nis calculated by the coupled electron and phonon Boltzmann transport equations,\nthe electrohydrodynamics model derived in this work, and the two-temperature\nmodel for different laser pulse durations, film thicknesses, and laser\nfluences. We find that the two-temperature model overestimates the electron\ntemperature at the frontsurface of the film and underestimates the damage\nthreshold when the nonlinear thermal transport of electrons is important. The\nelectrohydrodynamics model proposedin this work could be a more accurate\nprediction tool to study the non-equilibrium electron phonon transport process\nthan the two-temperature model and it is much easier to be solved than the\ncoupled electron and phonon Boltzmann transport equations."
    },
    {
        "anchor": "Electronic transport through carbon nanotubes -- effects of structural\n  deformation and tube chirality: Atomistic simulations using a combination of classical forcefield and\nDensity-Functional-Theory (DFT) show that carbon atoms remain essentially sp2\ncoordinated in either bent tubes or tubes pushed by an atomically sharp AFM\ntip. Subsequent Green's-function-based transport calculations reveal that for\narmchair tubes there is no significant drop in conductance, while for zigzag\ntubes the conductance can drop by several orders of magnitude in AFM-pushed\ntubes. The effect can be attributed to simple stretching of the tube under tip\ndeformation, which opens up an energy gap at the Fermi surface.",
        "positive": "Ni-PZT-Ni Trilayered Magnetoelectric composites Synthesized by\n  Electro-deposition: We report the high strength of magnetoelectric (ME) coupling of trilayered\ncomposites prepared by electro-deposition. The ME coupling of Ni-lead zirconate\ntitanate (PZT)-Ni trilayered structure was measured ranged from1 kHz to 120\nkHz. The trilayered composites exhibit high magnetoelectric voltage coefficient\nbecause of good bonding between piezoelectric and magnetostrictive layers. The\nmaximum magnetoelectric voltage coefficient can be up to 33 V/cm Oe at the\nelectromechanical resonance frequency. This magnetoelectric effect shows\npromising application in transducers for magnetoelectric energy conversion."
    },
    {
        "anchor": "Comment on \"Nonreciprocal cavities and the time-bandwidth limit\": In their paper in Optica 6, 104 (2019), Mann et al. claim that linear,\ntime-invariant nonreciprocal structures cannot overcome the time-bandwidth\nlimit, and do not exhibit an advantage over their reciprocal counterparts,\nspecifically with regard to their time-bandwidth performance. In this Comment\n[Optica 7(9), 1097-1101 (2020)], we argue that these conclusions are unfounded.\nOn the basis of, both, rigorous full-wave simulations and insightful physical\njustifications, we explain that the temporal coupled-mode theory, on which Mann\net al. base their main conclusions, is not suited for the study of\nnonreciprocal trapped states, and instead direct numerical solutions of\nMaxwell's equations are required. Based on such an analysis, we show that a\nnonreciprocal terminated waveguide, resulting in a trapped state, clearly\noutperforms its reciprocal counterpart, i.e. both the extraordinary\ntime-bandwidth performance and the large field enhancements observed in such\nmodes are a direct consequence of nonreciprocity. Additionally, herein, on the\narXiv, we provide further results and explanations on the key points made in\nthe main Comment, as well as further elucidating comments on the Reply to the\nComment.",
        "positive": "Exploring Solute Behavior and Texture Selection in Magnesium Alloys at\n  the Atomistic Level: This study advances our understanding of how chemical binding and solute\ndistribution impact grain boundary segregation behavior and subsequent\nannealing texture modification in lean Mg-X-Zn alloys (X = RE or Ca). Notably,\ndifferences in Ca and Gd solute behavior at grain boundaries were revealed,\nwhere Ca exhibited stronger binding to vacancy sites than Gd, resulting in\nelevated Ca segregation and an RD-TD-type texture. The introduction of Zn\nshowed significant synergistic effects on solute clustering, with Gd-Zn pairs\nforming more favorably than Ca-Zn pairs, leading to a strong synergy between Zn\nand Gd. This promoted their co-segregation and high concentration at the grain\nboundary, generating a unique TD-spread texture. In contrast, weaker binding in\nCa-Zn pairs did not affect Ca segregation but influenced Zn segregation, which\nunderscores the importance of solute binding behavior in alloy design concepts.\nAdditionally, the combined atomicscale experiments and ab initio predictions\nprovide strong evidence that selective texture development in Mg alloys is tied\nto heterogeneous solute-boundary interactions, where the sensitivity of the\nbinding energy to volumetric strain affects solute segregation at grain\nboundaries, resulting in varying grain boundary mobilities and specific texture\ncomponent growth. It also emphasizes that solute behavior in clustering and\nsegregation is influenced not only by atomic size but also by chemical binding\nstrength with vacancies or co-added Zn."
    },
    {
        "anchor": "Ferromagnetic helical nodal line and Kane-Mele spin-orbit coupling in\n  kagome metal Fe3Sn2: The two-dimensional kagome lattice hosts Dirac fermions at its Brillouin zone\ncorners K and K', analogous to the honeycomb lattice. In the density functional\ntheory electronic structure of ferromagnetic kagome metal Fe$_3$Sn$_2$, without\nspin-orbit coupling we identify two energetically split helical nodal lines\nwinding along $z$ in the vicinity of K and K' resulting from the trigonal\nstacking of the kagome layers. We find that hopping across A-A stacking\nintroduces a layer splitting in energy while that across A-B stacking controls\nthe momentum space amplitude of the helical nodal lines. The effect of\nspin-orbit coupling is found to resemble that of a Kane-Mele term, where the\nnodal lines can either be fully gapped to quasi-two-dimensional massive Dirac\nfermions, or remain gapless at discrete Weyl points depending on the\nferromagnetic moment orientation. Aside from numerically establishing\nFe$_3$Sn$_2$ as a model Dirac kagome metal, our results provide insights into\nmaterials design of topological phases from the lattice point of view, where\nparadigmatic low dimensional lattice models often find realizations in\ncrystalline materials with three-dimensional stacking.",
        "positive": "Scaling Properties of Polycrystalline Graphene: A Review: We present an overview of the electrical, mechanical, and thermal properties\nof polycrystalline graphene. Most global properties of this material, such as\nthe charge mobility, thermal conductivity, or Young's modulus, are sensitive to\nits microstructure, for instance the grain size and the presence of line or\npoint defects. Both the local and global features of polycrystalline graphene\nhave been investigated by a variety of simulations and experimental\nmeasurements. In this review, we summarize the properties of polycrystalline\ngraphene, and by establishing a perspective on how the microstructure impacts\nits large-scale physical properties, we aim to provide guidance for further\noptimization and improvement of applications based on this material, such as\nflexible and wearable electronics, and high-frequency or spintronic devices."
    },
    {
        "anchor": "Mechanisms of magnetoelectricity in manganese doped incipient\n  ferroelectrics: We report magnetization measurements and magnetic resonance data for SrTiO3\ndoped by manganese. We show that the recently reported coexistent spin and\ndipole glass (multiglass) behaviours are strongly affected by the distribution\nof Mn ions between the Sr and Ti sites. Motivated by this finding we calculate\nthe magnetic interactions between Mn impurities of different kinds. Both LSDA+U\nand many-body perturbation theory evidence that magnetic and magnetoelectric\ninteractions are mediated by Mn$_B^{4+}$ ions substituting for Ti. We propose\ntwo microscopic magnetoelectric coupling mechanisms, which can be involved in\nall magnetoelectric systems based on incipient ferroelectrics. In the first\none, the electric field modifies the spin susceptibility via spin-strain\ncoupling of Mn$_{B}^{4+}$. The second mechanism concerns Mn pairs coupled by\nthe position-dependent exchange interaction.",
        "positive": "Enhanced ZnTe infiltration in porous silicon by Isothermal Close Space\n  Sublimation: Isothermal Close Space Sublimation (ICSS) technique was used for embedding\nporous silicon (PS) films with ZnTe. It was studied the influence of the\npreparation conditions and in particular of a chemical etching step before the\nZnTe growth, on the composition profile and final porosity of ZnTe embedded PS.\nThe structure of the embedded material was determined by x-ray diffraction\nanalysis while the thickness of the samples was determined by scanning electron\nmicroscopy (SEM). Rutherford backscattering (RBS) and Energy Dispersive (EDS)\nspectrometries allowed determining the composition profiles. We conclude that\nthe etching of the PS surface before the ZnTe growth has two main effects: the\nincrease of the porosity and enhancing the reactivity of the inner surface. It\nwas observed that both effects benefit the filling process of the pores. Since\nRBS and EDS cannot detect the porosity in the present system, we explore the\nevolution of porosity by the fitting of the UV-VIS reflectance spectra. The\natomic percent determined with this method was in relatively good agreement\nwith that obtained from the RBS and EDS measurements."
    },
    {
        "anchor": "DyFraNet: Forecasting and Backcasting Dynamic Fracture Mechanics in\n  Space and Time Using a 2D-to-3D Deep Neural Network: The dynamics of materials failure is one of the most critical phenomena in a\nrange of scientific and engineering fields, from healthcare to structural\nmaterials to transportation. In this paper we propose a specially designed deep\nneural network, DyFraNet, which can predict dynamic fracture behaviors by\nidentifying a complete history of fracture propagation - from cracking onset,\nas a crack grows through the material, modeled as a series of frames evolving\nover time and dependent on each other. Furthermore, this model can not only\nforecast future fracture processes but also backcast to elucidate the past\nfracture history. In this scenario, once provided with the outcome of a\nfracture event, the model will elucidate past events that led to this state and\nwill predict the future evolution of the failure process. By comparing the\npredicted results with atomistic-level simulations and theory, we show that\nDyFraNet can capture dynamic fracture mechanics by accurately predicting how\ncracks develop over time, including measures such as the crack speed, as well\nas when cracks become unstable. We use GradCAM to interpret how DyFraNet\nperceives the relationship between geometric conditions and fracture dynamics\nand we find DyFraNet pays special attention to the areas around crack tips,\nwhich have a critical influence in the early stage of fracture propagation. In\nlater stages, the model pays increased attention to the existing or newly\nformed damage distribution in the material. The proposed approach offers\nsignificant potential to accelerate the exploration of the dynamics in material\ndesign against fracture failures and can be beneficially adapted for all kinds\nof dynamical engineering problems.",
        "positive": "Raman study of lattice dynamics in quasicrystals: We present the first Raman investigation of icosahedral quasicrystals. Broad\nstructured bands in the energy range up to ~ 500 $cm^{-1} have been observed in\na series of AlFeCu, AlPdMn and AlPdRe systems. Original information on the\nvibrational density of states g(omega) was obtained for AlPdRe; for AlFeCu and\nAlPdMn estimated g(omega) shows a good agreement with the previous neutron\nresults, but demonstrates finer structure. Strong increase in the parameter of\nelectron-vibrational coupling for the low-energy vibrations and its correlation\nwith changes in electronic conductivity has been observed in the series from\nAlFeCu to AlPdRe. This suggests the increase of the degree of localization for\nthese vibrational excitations and involved electronic states."
    },
    {
        "anchor": "Correlation between the structural and optical properties of\n  spontaneously formed GaN nanowires: a quantitative evaluation of the impact\n  of nanowire coalescence: We investigate the structural and optical properties of spontaneously formed\nGaN nanowires with different degrees of coalescence. This quantity is\ndetermined by an analysis of the cross-sectional area and perimeter of the\nnanowires obtained by plan-view scanning electron microscopy. X-ray diffraction\nexperiments are used to measure the inhomogeneous strain in the nanowire\nensembles as well as the orientational distribution of the nanowires. The\ncomparison of the results obtained for GaN nanowire ensembles prepared on bare\nSi(111) and AlN buffered 6H-SiC(000-1) reveals that the main source of the\ninhomogeneous strain is the random distortions caused by the coalescence of\nadjacent nanowires. The magnitude of the strain inhomogeneity induced by\nnanowire coalescence is found not to be determined solely by the coalescence\ndegree, but also by the mutual misorientation of the coalesced nanowires. The\nlinewidth of the donor-bound exciton transition in photoluminescence spectra\ndoes not exhibit a monotonic increase with the coalescence degree. In contrast,\nthe comparison of the root mean square strain with the linewidth of the\ndonor-bound exciton transition reveals a clear correlation: the higher the\nstrain inhomogeneity, the larger the linewidth.",
        "positive": "Terahertz ellipsometry study of the soft mode behavior in ultrathin\n  SrTiO3 films: We present a combined study with conventional far-infrared and time-domain\nterahertz ellipsometry of the temperature dependent optical response of SrTiO3\nthin films (85 and 8.5 nm) that are grown by pulsed-laser deposition on LSAT\nsubstrates. We demonstrate that terahertz ellipsometry is very sensitive to the\noptical response of these thin films, in particular, to the soft mode of\nSrTiO3. We show that for the 85 nm film the eigenfrequency of the soft mode is\nstrongly reduced by annealing at 1200 C, whereas for the 8.5 nm film it is\nhardy affected. For the latter, after annealing the mode remains at 125 cm-1 at\n300 K and exhibits only a weak softening to about 90 cm-1 at 10 K. This\nsuggests that this ultrathin film undergoes hardly any relaxation of the\ncompressive strain due to the LSAT substrate."
    },
    {
        "anchor": "Structural studies of thin films of semiconducting nanoparticles in\n  polymer matrices: We deposited thin layers of CdS and ZnS nanoparticles embedded in a\nthermoplastic cyclo-olephin copolymer (COC) with elevated optical transparency\nand highly bio-compatible. The nanoparticles were obtained by thiolate\nprecursors previously dispersed in the polymer upon thermal treatment at\ntemperatures ranging between 200 and 300 Celsius degrees depending on the\ndesired size. The precursor/polymer solutions were spin coated in order to get\nthin films. The samples were mainly characterised by X-ray reflectivity (XRR)\nand by High Resolution Transmission Electron Microscopy (HRTEM) analyses. The\nHRTEM measurements showed that the nanoparticles have quasi-spherical shape\nwithout evident microstructural defects. The size of the nanoparticles depends\non the annealing temperature, e.g. at 232 Celsius degrees the size of the CdS\nnanoparticles is about 4-5 nm.",
        "positive": "Atomic arrangement of van der Waals heterostructures using X-ray\n  scattering and crystal truncation rod analysis: Vanadium diselenide (VSe2) has intriguing physical properties such as\nunexpected ferromagnetism at the two-dimensional limit. However, the\nexperimental results for room temperature ferromagnetism are still\ncontroversial and depend on the detailed crystal structure and stoichiometry.\nHere we introduce crystal truncation rod (CTR) analysis to investigate the\natomic arrangement of bilayer VSe2 and bilayer graphene (BLG) hetero-structures\ngrown on a 6H-SiC(0001) substrate. Using non-destructive CTR analysis, we were\nable to obtain electron density profiles and detailed crystal structure of the\nVSe2/BLG heterostructures. Specifically, the out-of-plane lattice parameters of\neach VSe2 layer were modulated by the interface compared to that of the bulk\nVSe2 1T phase. The atomic arrangement of the VSe2/BLG heterostructure provides\ndeeper understanding and insight for elucidating the magnetic properties of the\nvan der Waals heterostructure."
    },
    {
        "anchor": "Observation of plastoferrite character and semiconductor to metal\n  transition in soft ferromagnetic Li0.5Mn0.5Fe2O4ferrite: We prepared Li0.5Mn0.5Fe2O4 ferrite through chemical reaction in highly\nacidic solution and subsequent sintering of chemical routed powder at\ntemperatures > 800 0C. Surface morphology showed plastoferrite character for\nsintering temperature > 1000 0C. Mechanical softening of metal-oxygen bonds at\nhigher measurement temperatures stimulated delocalization of charge carriers,\nwhich were strongly localized in A and B sites of the spinel structure at lower\ntemperatures. The charge delocalization process has activated semiconductor to\nmetallic transition in ac conductivity curves, obeyed by Jonscher power law and\nDrude equation, respectively. Metallic state is also confirmed by the frequency\ndependence of dielectric constant curves.",
        "positive": "Search for the magnetic monopole at a magnetoelectric surface: We show, by solving Maxwell's equations, that an electric charge on the\nsurface of a slab of a linear magnetoelectric material generates an image\nmagnetic monopole below the surface provided that the magnetoelectric has a\ndiagonal component in its magnetoelectric response. The image monopole, in\nturn, generates an ideal monopolar magnetic field outside of the slab. Using\nrealistic values of the electric- and magnetic- field susceptibilties, we\ncalculate the magnitude of the effect for the prototypical magnetoelectric\nmaterial Cr$_2$O$_3$. We use low energy muon spin rotation to measure the\nstrength of the magnetic field generated by charged muons as a function of\ntheir distance from the surface of a Cr$_2$O$_3$ films, and show that the\nresults are consistent with the existence of the monopole. We discuss other\npossible routes to detecting the monopolar field, and show that, while the\npredicted monopolar field generated by Cr$_2$O$_3$ is above the detection limit\nfor standard magnetic force microscopy, detection of the field using this\ntechnique is prevented by surface charging effects."
    },
    {
        "anchor": "Procedures for assessing the stability of proposed topological materials: We investigate the stability of MnPb$_{2}$Bi$_{2}$Te$_{6}$ (MPBT), which is\npredicted to be a magnetic topological insulator (TI), using density functional\ntheory calculations. Our analysis includes various measures such as enthalpies\nof formation, Helmholtz free energies, defect formation energies, and dynamical\nstability. Our thermodynamic analysis shows that the phonon contribution to the\nenergy gain from finite temperature is estimated to be less than 10~meV/atom,\nwhich may not be sufficient to stabilize MPBT at high temperatures, even with\nthe most favorable reactions starting from binaries. While MPBT is generally\nrobust against the formation of various defects, we find that anti-site defect\nformation of $\\text{Mn}_{\\text{Pb}}$ is the most likely to occur, with\ncorresponding energy less than 60~meV. This can be attributed to the\nsignificant energy cost from compressive strain at the PbTe layer. Our findings\nsuggest that MPBT is on the brink of stability in terms of thermodynamics and\ndefect formation, underscoring the importance of conducting systematic analyses\nof the stability of proposed TIs, including MPBT, for their practical\nutilization. This study offers valuable insights into the design and synthesis\nof desirable magnetic TI materials with robust stabilities.",
        "positive": "Role of the presence of transition-metal atoms at the antisites in CrAs,\n  CrSe and VAs zinc-blende compounds: In a recent publication [Galanakis I et al 2006 \\PR B \\textbf{74} 140408(R)]\nwe have shown that in the case of CrAs and related transition-metal\nchalcogenides and pnictides, crystallizing in the zinc-blende structure, the\nexcess of the transition-metal atoms leads to half-metallic ferrimagnetism. The\nlatter property is crucial for spintronic applications with respect to\nferromagnets due to the lower stray fields created by these materials. We\nextend this study to cover the case where the transition-metal atoms sitting at\nantisites are not identical to the ones in the perfect sites. In Cr-based\ncompounds, the creation of Mn antisites keeps the half-metallic ferrimagnetic\ncharacter produced also by the Cr antisites. In the case of VAs, Cr and Mn\nantisites keep the half-metallic character of VAs (contrary to V antisites) due\nto the larger exchange-splitting exhibited by these atoms."
    },
    {
        "anchor": "Non-adiabatic suppression of 3D excitonic screening in black phosphorus\n  by mid-infrared pulses: The competition between the electron-hole Coulomb attraction and the\nthree-dimensional dielectric screening dictates the optical properties of\nlayered semiconductors. In low-dimensional materials, the equilibrium\ndielectric environment can be significantly altered by the ultrafast excitation\nof photo-carriers, leading to renormalized band gap and exciton binding\nenergies. Recently, black phosphorus emerged as a 2D material with strongly\nlayer-dependent electronic properties. Here, we resolve the coherent response\nof screening to sub-gap photo-excitation in bulk black phosphorus and find that\nmid-infrared pulses tuned across the band gap drive a transient non-thermal\nsuppression of the dielectric screening, which is revealed by the emergence of\nthe single-layer exciton resonance. Our work exposes the role of interlayer\ninteractions in determining the electronic properties of 2D materials and\ndiscloses the possibility of optically manipulate them, which is of great\nrelevance for the engineering of versatile van der Waals low-dimensional\nmaterials.",
        "positive": "Current induced torques and interfacial spin-orbit coupling:\n  Semiclassical Modeling: In bilayer nanowires consisting of a ferromagnetic layer and a non-magnetic\nlayer with strong spin-orbit coupling, currents create torques on the\nmagnetization beyond those found in simple ferromagnetic nanowires. The\nresulting magnetic dynamics appear to require torques that can be separated\ninto two terms, damping-like and field-like. The damping-like torque is\ntypically derived from models describing the bulk spin Hall effect and the spin\ntransfer torque, and the field-like torque is typically derived from a Rashba\nmodel describing interfacial spin-orbit coupling. We derive a model based on\nthe Boltzmann equation that unifies these approaches. We also consider an\napproximation to the Boltzmann equation, the drift-diffusion model, that\nqualitatively reproduces the behavior, but quantitatively fails to reproduce\nthe results. We show that the Boltzmann equation with physically reasonable\nparameters can match the torques for any particular sample, but in some cases,\nit fails to describe the experimentally observed thickness dependences."
    },
    {
        "anchor": "Intrinsic Rippling Enhances Static Non-Reciprocity in Graphene\n  Metamaterials: In mechanical systems, Maxwell-Betti reciprocity means that the displacement\nat point B in response to a force at point A is the same as the displacement at\npoint A in response to the same force applied at point B. Because the notion of\nreciprocity is general, fundamental, and is operant for other physical systems\nlike electromagnetics, acoustics, and optics, there is significant interest in\nunderstanding systems that are not reciprocal, or exhibit non-reciprocity.\nHowever, most studies of non-reciprocity have occurred in bulk-scale structures\nfor dynamic problems involving time reversal symmetry. As a result, little is\nknown about the mechanisms governing static non-reciprocal responses,\nparticularly in atomically-thin two-dimensional materials like graphene. Here,\nwe use classical atomistic simulations to demonstrate that out of plane\nripples, which are intrinsic to graphene, enable significant, multiple orders\nof magnitude enhancements in the statically non-reciprocal response of graphene\nmetamaterials. Specifically, we find that a striking interplay between the\nripples and the stress fields that are induced in the metamaterials due to\ntheir geometry impact the displacements that are transmitted by the\nmetamaterial, thus leading to a significantly enhanced static non-reciprocal\nresponse. This study thus demonstrates the potential of two-dimensional\nmechanical metamaterials for symmetry-breaking applications.",
        "positive": "Direct Observation of Early-stage Quantum Dot Growth Mechanisms with\n  High-temperature Ab Initio Molecular Dynamics: Colloidal quantum dots (QDs) exhibit highly desirable size- and\nshape-dependent properties for applications from electronic devices to imaging.\nIndium phosphide QDs have emerged as a primary candidate to replace the more\ntoxic CdSe QDs, but production of InP QDs with the desired properties lags\nbehind other QD materials due to a poor understanding of how to tune the growth\nprocess. Using high-temperature ab initio molecular dynamics (AIMD)\nsimulations, we report the first direct observation of the early stage\nintermediates and subsequent formation of an InP cluster from separated indium\nand phosphorus precursors. In our simulations, indium agglomeration precedes\nformation of In-P bonds. We observe a predominantly intercomplex pathway in\nwhich In-P bonds form between one set of precursor copies while the carboxylate\nligand of a second indium precursor in the agglomerated indium abstracts a\nligand from the phosphorus precursor. This process produces an indium-rich\ncluster with structural properties comparable to those in bulk zinc-blende InP\ncrystals. Minimum energy pathway characterization of the AIMD-sampled reaction\nevents confirms these observations and identifies that In-carboxylate\ndissociation energetics solely determine the barrier along the In-P bond\nformation pathway, which is lower for intercomplex (13 kcal/mol) than\nintracomplex (21 kcal/mol) mechanisms. The phosphorus precursor chemistry, on\nthe other hand, controls the thermodynamics of the reaction. Our observations\nof the differing roles of precursors in controlling QD formation strongly\nsuggests that the challenges thus far encountered in InP QD synthesis\noptimization may be attributed to an overlooked need for a cooperative tuning\nstrategy that simultaneously addresses the chemistry of both indium and\nphosphorus precursors."
    },
    {
        "anchor": "Solitons and exact velocity quantization of incommensurate sliders: We analyze in some detail the recently discovered velocity quantization\nphenomena in the classical motion of an idealized one-dimensional solid\nlubricant, consisting of a harmonic chain interposed between two periodic\nsliders. The ratio w = v_cm/v_ext of the chain center-of-mass velocity to the\nexternally imposed relative velocity of the sliders is pinned to exact\n``plateau'' values for wide ranges of parameters, such as sliders corrugation\namplitudes, external velocity, chain stiffness and dissipation, and is strictly\ndetermined by the commensurability ratios alone. The phenomenon is caused by\none slider rigidly dragging the density solitons (kinks/antikinks) that the\nchain forms with the other slider. Possible consequences of these results for\nsome real systems are discussed.",
        "positive": "Structural transitions, magnetic properties, and electronic structures\n  of Co(Fe)-doped MnNiSi compounds: The structural transitions, magnetic properties, and electronic structures of\nCo(Fe)-doped MnNiSi compounds are investigated by x-ray powder diffraction\n(XRD), differential scanning calorimetry (DSC), magnetic measurements, and\nfirst-principles calculations. Results indicate that all samples undergo a\nmartensitic transition from the Ni2In-type parent phase to TiNiSi-type\northorhombic phase at high temperatures. The substitution of Co(Fe) for Mn in\nMn1-xCoxNiSi (x = 0.2, 0.3, 0.4) and Mn1-yFeyNiSi (y = 0.26, 0.30, 0.36, 0.46,\n0.55) samples decreases the structural transition temperature (Tt) and Curie\ntemperature of martensite (TCM). The martensite phases show a typical\nferromagnetic behavior with saturation field (HS) being basically unchanged\nwith increasing Co(Fe) content, while the saturation magnetization (MS) shows a\ndecreasing tendency. The theoretically calculated moments are in good agreement\nwith the experimentally measured results. The orbital hybridizations between\ndifferent 3d elements are analyzed from the distribution of density of states."
    },
    {
        "anchor": "Main physical characteristics of crystal, magnetic and electronic\n  structures of Ce3+-based perovskites CeTmO3 [Tm3+ = Sc, Ti, V] investigated\n  via the first-principles computational utilizing LDA, PBE-GGA and WC-GGA\n  functionals: Main physical characteristics, crystal, magnetic and electronic structures,\nof cerium-based perovskites CeTmO3 [Tm3+ = Sc, Ti, V] are systematically\ninvestigated via the first-principles computations. Full-potential linear\naugmented plane-wave with the local density approximation and generalized\ngradient approximation, under Perdew-Burke-Ernzerh and Wu-Cohen, based on DFT.\nThe optimized crystal parameters indicate that the crystal of compounds can\ncategorized under cubic structure (space group Pm-3m, no. 221), and their\nobtained lattice constants in good agreement with the available experimental\nvalues. The computed electronic band structures, density of states (DOS) and\ncharge density reveal the metallic nature for CeTmO3, except for [Tm3+ = Sc],\nexhibits half-metallic characteristics. Besides, all functionals provide nearly\nsimilar results of crystal structures, DOSs as well as spin magnetic moments\nconfirm that the CeTmO3 are ferromagnetic (FM) metals.",
        "positive": "Room temperature dielectric and magnetic properties of Gd and Ti\n  co-doped BiFeO$_{3}$ ceramics: Room temperature dielectric and magnetic properties of BiFeO$_3$ samples,\nco-doped with magnetic Gd and non-magnetic Ti in place of Bi and Fe,\nrespectively, were reported. The nominal compositions of\nBi$_{0.9}$Gd$_{0.1}$Fe$_{1-x}$Ti$_x$O$_3$ (x = 0.00-0.25) ceramics were\nsynthesized by conventional solid state reaction technique. X-ray diffraction\npatterns revealed that the substitution of Fe by Ti induces a phase transition\nfrom rhombohedral to orthorhombic at x $>$ 0.20. Morphological studies\ndemonstrated that the average grain size was reduced from $\\sim {~}$1.5 $\\mu m$\nto $\\sim {~}$200 $nm$ with the increase in Ti content. Due to Ti substitution,\nthe dielectric constant was stable over a wide range of high frequencies (30\nkHz to 20 MHz) by suppressing the dispersion at low frequencies. The dielectric\nproperties of the compounds are associated with their improved morphologies and\nreduced leakage current densities probably due to the lower concentration of\noxygen vacancies in the compositions. Magnetic properties of\nBi$_{0.9}$Gd$_{0.1}$Fe$_{1-x}$Ti$_x$O$_3$ (x = 0.00-0.25) ceramics measured at\nroom temperature were enhanced with Ti substitution up to 20 $\\%$ compared to\nthat of pure BiFeO$_3$ and Ti undoped Bi$_{0.9}$Gd$_{0.1}$FeO$_3$ samples. The\nenhanced magnetic properties might be attributed to the substitution induced\nsuppression of spiral spin structure of BiFeO$_3$. An asymmetric shifts both in\nthe field and magnetization axes of magnetization versus magnetic field (M-H)\ncurves was observed. This indicates the presence of exchange bias effect in\nthese compounds notably at room temperature."
    },
    {
        "anchor": "On the nature of large-scale defect accumulations in Czochralski-grown\n  silicon: Czochralski-grown boron-doped silicon crystals were studied by the techniques\nof the low-angle mid-IR-light scattering and electron-beam-induced current. The\nlarge-scale accumulations of electrically-active impurities detected in this\nmaterial were found to be different in their nature and formation mechanisms\nfrom the well-known impurity clouds in a float zone-grown silicon. A\nclassifcation of the large-scale impurity accumulations in CZ Si:B is made and\npoint centers constituting them are analyzed in this paper. A model of the\nlarge-scale impurity accumulations in CZ-grown Si:B is also proposed.",
        "positive": "High field properties of typical perovskite ferroelectrics by\n  first-principles modeling: Using first-principles calculations, we estimated the impact of large applied\nelectric E fields on the structural, dielectric, and ferroelectric properties\nof typical ferroelectrics. At large fields, the structural parameters change\nsignificantly, decreasing the strain between the different structural phases.\nThis effect favours a polarization rotation model for ferroelectric switching\nin which the electronic polarization rotates between the directions of\ntetragonal, rhombohedral and orthorhombic phases. We estimate coercive fields\nE_c ~31 MV/m and ~52 MV/m at zero temperature for bulk ferroelectric\nmonodomains of BaTiO3 and PbTiO3, respectively. The dielectric permittivity and\ntunability of BaTiO3 are the least affected at large fields, making this\nmaterial attractive for applications in electronics and energy storage."
    },
    {
        "anchor": "Carrier transport properties of the Group-IV ferromagnetic semiconductor\n  Ge1-xFex with and without boron doping: We have investigated the transport and magnetic properties of group-IV\nferromagnetic semiconductor Ge1-xFex films (x = 1.0 and 2.3 %) with and without\nboron doping grown by molecular beam epitaxy (MBE). In order to accurately\nmeasure the transport properties of 100-nm-thick Ge1-xFex films, (001)-oriented\nsilicon-on-insulator (SOI) wafers with an ultra-thin Si body layer (~5 nm) were\nused as substrates. Owing to the low Fe content, the hole concentration and\nmobility in the Ge1-xFex films were exactly estimated by Hall measurements\nbecause the anomalous Hall effect in these films was found to be negligibly\nsmall. By boron doping, we increased the hole concentration in Ge1-xFex from\n~1018 cm-3 to ~1020 cm-3 (x = 1.0%) and to ~1019 cm-3 (x = 2.3%), but no\ncorrelation was observed between the hole concentration and magnetic\nproperties. This result presents a contrast to the hole-induced ferromagnetism\nin III-V ferromagnetic semiconductors.",
        "positive": "Spin direction controlled electronic band structure in two dimensional\n  ferromagnetic CrI3: Manipulating physical properties using the spin degree of freedom constitutes\na major part of modern condensed matter physics and is very important for\nspintronics devices. Using the newly discovered two dimensional van der Waals\nferromagnetic CrI3 as a prototypic material, we theoretically demonstrated a\ngiant magneto band-structure (GMB) effect whereby a change of magnetization\ndirection significantly modifies the electronic band structure. Our density\nfunctional theory calculations and model analysis reveal that rotating the\nmagnetic moment of CrI3 from out-of-plane to in-plane causes a\ndirect-to-indirect bandgap transition, inducing a magnetic field controlled\nphotoluminescence. Moreover, our results show a significant change of Fermi\nsurface with different magnetization directions, giving rise to giant\nanisotropic magnetoresistance. Additionally, the spin reorientation is found to\nmodify the topological states. Given that a variety of properties are\ndetermined by band structures, our predicted GMB effect in CrI3 opens a new\nparadigm for spintronics applications."
    },
    {
        "anchor": "Study of F4TCNQ dopant diffusion using transport measurements in organic\n  semiconductors: In this paper, we report on electrical transport in F4TCNQ doped organic\nsemiconductor (host) materials. By monitoring the conductance of the sample\nin-situ during and after deposition, we show that sequential deposition of\nF4TCNQ and host semiconductor results in bulk doping of the semiconductor. In\naddition, the doping density (and conductivity) of the host can be easily\ncontrolled by adjusting the thickness of the bottom F4TCNQ layer. This\nalternative scheme for doping is simpler than the conventional way of doping\nsmall molecules which involves simultaneous co-evaporation of host and dopant.\nIn the sequential doping scheme outlined here, bulk doping of the host takes\nplace due to rapid diffusion of F4TCNQ in the host material. The motion of\nF4TCNQ in the host is complex and is not always described by a simple diffusion\nprocess. In situ transport measurements provide a quick and easy way of\nmeasuring dopant diffusion in new hosts. Based on the doping results, we also\noutline a possible route to improved transconductance for organic thin film\ntransistors in a manufacturing environment.",
        "positive": "High spin polarization and large spin splitting in equiatomic quaternary\n  CoFeCrAl Heusler alloy: In this paper, we investigate CoFeCrAl alloy by means of various experimental\ntechniques and ab-initio calculations to look for half-metallic nature. The\nalloy is found to exist in the cubic Heusler structure, with presence of B2\nordering. Saturation magnetization (MS) value of about 2 Bohr magneton/f.u. is\nobserved at 8 K under ambient pressure, which is in good agreement with the\nSlater-Pauling rule. MS values are found to be independent of pressure, which\nis a prerequisite for half-metals. The ab-initio electronic structure\ncalculations predict half-metallic nature for the alloy with a spin slitting\nenergy of 0.31 eV. Importantly, this system shows a high current spin\npolarization value of 0.67 [with error of 0.02], as deduced from the point\ncontact Andreev reflection (PCAR) measurements. Linear dependence of electrical\nresistivity with temperature indicates the possibility of reasonably high spin\npolarization at elevated temperatures (~150 K) as well. All these suggest that\nCoFeCrAl is a promising material for the spintronic devices."
    },
    {
        "anchor": "Multiscale simulations of growth-dominated Sb$_2$Te phase-change\n  material for non-volatile photonic applications: Chalcogenide phase-change materials (PCMs) are widely applied in electronic\nand photonic applications, such as non-volatile memory and neuro-inspired\ncomputing. Doped Sb$_2$Te alloys are now gaining increasing attention for\non-chip photonic applications, due to their growth-driven crystallization\nfeatures. However, it remains unknown whether Sb$_2$Te also forms a metastable\ncrystalline phase upon nanoseconds crystallization in devices, similar to the\ncase of nucleation-driven Ge-Sb-Te alloys. Here, we carry out ab initio\nsimulations to understand the changes in optical properties of amorphous\nSb$_2$Te upon crystallization and post annealing. During the continuous\ntransformation process, changes in the dielectric function are highly\nwavelength-dependent from the visible-light range towards the telecommunication\nband. Our finite-difference time-domain simulations based on the ab initio\ninput reveal key differences in device output for color display and photonic\nmemory applications upon tellurium ordering. Our work serves as an example of\nhow multiscale simulations of materials can guide practical photonic\nphase-change applications.",
        "positive": "Solute Segregation in a Moving Grain Boundary: A Novel Phase-Field\n  Approach: We present a novel phase-field approach for investigating solute segregation\nin a moving grain boundary. In our model, the correct choice of various\nparameters can control the solute-grain boundary interaction potential,\nresulting in various segregation profiles that agree with Cahn solute drag\ntheory. Furthermore, we explore how different segregation profiles evolve at\nvarying GB velocities owing to the inequality of the atomic flux of solute\nbetween the front and back faces of the moving grain boundary. We highlight\nvelocity variations among segregation profiles in low and high-velocity\nregimes. This model reveals how grain boundary segregation affects grain\ngrowth, providing insights for future alloy design"
    },
    {
        "anchor": "The calculation of the diffusion coefficients in ternary multiphase\n  Ti-NiAl system: In this paper the problem of determination of the diffusion coefficients in a\nternary multiphase system is discussed. In the literature there is a lack of\ndata concerning the approximation method which allows to determine diffusion\ncoefficients in such complicated systems. We propose the mass conservation\nmethod (MCA) for calculation the diffusivities in phases where the differences\nin composition is linear. Only one experimental results is needed for\ndetermination of the diffusion data. The method is implemented and checked\nunder ternary Ti-NiAl system - this system characterize occurrence three\nintermetallic phases in diffusion couple Ti-NiAl.",
        "positive": "Trimethylaluminum Diffusion in PMMA Thin Films during Sequential\n  Infiltration Synthesis: In Situ Dynamic Spectroscopic Ellipsometric\n  Investigation: Sequential infiltration synthesis (SIS) provides a successful route to grow\ninorganic materials into polymeric films by penetrating of gaseous precursors\ninto the polymer, both in order to enhance the functional properties of the\npolymer creating an organic-inorganic hybrid material, and to fabricate\ninorganic nanostructures when infiltrating in patterned polymer films or in\nselfassembled block copolymers. A SIS process consists in a controlled sequence\nof metal organic precursor and co-reactant vapor exposure cycles of the polymer\nfilms in an atomic layer deposition (ALD) reactor. In this work, we present a\nstudy of the SIS process of alumina using trimethylaluminum (TMA) and H2O in\nvarious polymer films using in situ dynamic spectroscopic ellipsometry (SE). In\nsitu dynamic SE enables time-resolved monitoring of the swelling of the\npolymer, which is relevant to the diffusion and retain of the metal precursor\ninto the polymer itself. Different swelling behaviour of\npoly(methylmethacrylate) (PMMA) and polystyrene (PS) was observed when exposed\nto TMA vapor. PMMA films swell more significantly than PS films do, resulting\nin very different infiltrated Al2O3 thickness after polymer removal in O2\nplasma. PMMA films reach different swollen states upon TMA exposure and\nreaction with H2O, depending on the TMA dose and on the purge duration after\nTMA exposure, which correspond to different amounts of metal precursor retained\ninside the polymer and converted to alumina. Diffusion coefficients of TMA in\nPMMA were extracted investigating the swelling of pristine PMMA films during\nTMA infiltration and shown to be dependent on polymer molecular weight. In situ\ndynamic SE monitoring allows to control the SIS process tuning it from an\nALD-like process for long purge to a chemical vapour deposition - like process\nselectively confined inside the polymer films"
    },
    {
        "anchor": "Thermodynamics of Surface Defects at the Aspirin/Water Interface: We present a simulation scheme to calculate defect formation free energies at\na molecular crystal/water interface based on force-field molecular dynamics\n(MD) simulations. To this end we adopt and modify existing approaches to\ncalculate binding free energies of biological ligand/receptor complexes to be\napplicable to common surface defects, such as step edges and kink sites. We\nobtain statistically accurate and reliable free energy values for the\naspirin/water interface, which can be applied to estimate the distribution of\ndefects using well-established thermodynamic relations. As a show case we\ncalculate the free energy upon dissolving molecules from kink sites at the\ninterface. This free energy can be related to the solubility concentration and\nwe obtain solubility values in excellent agreement with experimental results.",
        "positive": "Theory of hypothetical ferroelectric superlattices incorporating\n  head-to-head and tail-to-tail 180$^\\circ$ domain walls: While electrical compatibility constraints normally prevent head-to-head (HH)\nand tail-to-tail (TT) domain walls from forming in ferroelectric materials, we\npropose that such domain walls could be stabilized by intentional growth of\natomic layers in which the cations are substituted from a neighboring column of\nthe periodic table. In particular, we carry out predictive first-principles\ncalculations of superlattices in which Sc, Nb, or other substitutional layers\nare inserted periodically into PbTiO$_3$. We confirm that this gives rise to a\ndomain structure with the longitudinal component of the polarization\nalternating from domain to domain, and with the substitutional layers serving\nas HH and TT domain walls. We also find that a substantial transverse component\nof the polarization can also be present."
    },
    {
        "anchor": "Atomic layer deposition of HfO2 on graphene from HfCl4 and H20: Atomic layer deposition of ultrathin HfO2 on unmodified graphene from HfCl4\nand H2O was investigated. Surface RMS roughness down to 0.5 nm was obtained for\namorphous, 30 nm thick hafnia film grown at 180 degrees C. HfO2 was deposited\nalso in a two-step temperature process where the initial growth of about 1 nm\nat 170 degrees C was continued up to 10-30 nm at 300 degrees C. This process\nyielded uniform, monoclinic HfO2 films with RMS roughness of 1.7 nm for 10-12\nnm thick films and 2.5 nm for 30 nm thick films. Raman spectroscopy studies\nrevealed that the deposition process caused compressive biaxial strain in\ngraphene whereas no extra defects were generated. An 11 nm thick HfO2 film\ndeposited onto bilayer graphene reduced the electron mobility by less than 10%\nat the Dirac point and by 30-40% far away from it.",
        "positive": "Low Temperature Ageing Behaviour of U-Nb $\u03b3^{o}$ Phase Alloys: Ageing mechanisms of the U-7\\%wtNb alloy have been investigated on samples\nexposed to temperatures of 150$^{o}$C for up to 5000\\,hours. A variety of\nsurface and bulk analytic techniques have been used to investigate\nmicrostructural, chemical and crystallographic changes. Characterisation of the\nalloy's evolving behaviour was carried out through secondary electron\nmicroscopy, energy dispersive x-ray spectroscopy, electron backscatter\ndiffraction, transmission electron microscopy and x-ray diffraction. Vickers\nhardness testing showed evidence of a strong thermal hardening relationship\nwith ageing. The mechanism responsible for these changes is thought to be a\nstress-induced isothermal martensitic transformation; a displacive reaction, in\nwhich correlated shuffling of atoms creates a phase change from $\\gamma^{o}$ to\n$\\alpha''$ without chemical species redistribution."
    },
    {
        "anchor": "Separate magnetization switching of hexagonal Co/BN/Co junctions grown\n  epitaxially on c-sapphire: Magnetic tunnel junctions (MTJ) have been grown by using molecular beam\nepitaxy on c-plane Al2O3 substrates. The MTJ stacks consist of two\nferromagnetic hcp-Co layers separated by a thin insulating h-BN barrier. The\nsamples have been grown in a single run revealing single crystalline epitaxial\nstructures with sharp interfaces as observed by applying transmission electron\nmicroscopy. The in-plane magnetization experiments have revealed separate\nmagnetization switching of a thin top Co (soft) layer and a thick bottom Co\n(hard) layer. At zero magnetic field the two Co layers are found in an\nantiparallel state.",
        "positive": "Intrinsic effects of the boundary condition on switching processes in\n  spin-crossover solids: We investigated domain growth in switching processes between the low-spin and\nhigh-spin phases in thermally induced hysteresis loops of spin-crossover (SC)\nsolids. Elastic interactions among the molecules induce effective long-range\ninteractions, and thus the boundary condition plays a significant role in the\ndynamics. In contrast to SC systems with periodic boundary conditions, where\nuniform configurations are maintained during the switching process, we found\nthat domain structures appear with open boundary conditions. Unlike Ising-like\nmodels with short-range interactions, domains always grow from the corners of\nthe system. The present clustering mechanism provides an insight into the\nswitching dynamics of SC solids, in particular, in nano-scale systems."
    },
    {
        "anchor": "Experimental and theoretical study of processes of formation and growth\n  of pearlite colonies in eutectoid steels: We describe our optical and electron-microscopy observations of pearlite\nstructures in eutectoid steels which seem to imply that the mechanisms of\nformation of pearlite colonies in these steels differ from those observed\nearlier for non-eutectoid steels. A simple theoretical model to study kinetics\nof pearlite transformations is suggested. Simulations of growth of pearlite\ncolonies based on this model reveal that for the volume carbon diffusion\nmechanism usually-supposed such growth is always unstable, and the steady-state\ngrowth can be realized only via the interfacial carbon diffusion mechanism. A\nmodel of formation of pearlite colonies based on the assumption of a strong\nenhancement of carbon diffusion near grain boundaries is also suggested. The\nmodel can be applicable to the plastically deformed steels, and the results of\nsimulations based on this model qualitatively agree with some microstructural\nfeatures of formation of pearlite colonies observed in such steels.",
        "positive": "Knowledge-Transfer based Cost-effective Search for Interface Structures:\n  A Case Study on fcc-Al [110] Tilt Grain Boundary: Determining the atomic configuration of an interface is one of the most\nimportant issues in materials science research. Although theoretical\nsimulations are effective tools, an exhaustive search is computationally\nprohibitive due to the high degrees of freedom of the interface structure. In\nthe interface structure search, multiple energy surfaces created by a variety\nof orientation angles need to be explored, and the necessary computational\ncosts for different angles vary substantially owing to significant variations\nin the supercell sizes. In this paper, we introduce two machine-learning\nconcepts, called transfer learning and cost-sensitive search, to the\ninterface-structure search. As a case study, we demonstrate the effectiveness\nof our method, called cost-sensitive multi-task Bayesian optimization (CMB),\nusing the fcc-Al [110] tilt grain boundary. Four microscopic parameters, the\nthree-dimensional rigid body translation, and the number of atomic columns, are\noptimized by transferring knowledge of energy surfaces among different\norientation angles. We show that transferring knowledge of different energy\nsurfaces can accelerate the structure search, and that considering the cost\nvariations further improves the total efficiency."
    },
    {
        "anchor": "Janus particles with coupled electric and magnetic moments make a\n  disordered magneto-electric medium: We demonstrate that by combining permanent electric and magnetic moments in\nparticles, it is possible to realize a new type of medium that allows for a\ncross-correlation between electric and magnetic properties of matter, known as\nmagnetoelectric coupling. Magnetoelectric materials have so far been restricted\nto systems that exhibit long-range order in their electric and magnetic\nmoments. Here, we show that a room-temperature, switchable magnetoelectric can\nbe realized that is naturally disordered. The building blocks are Tellegen\nparticles that orient in either an electric or a magnetic field.",
        "positive": "Ab-initio insights into the pressure dependent physical properties and\n  possible high-Tc superconductivity in monoclinic and orthorhombic MgVH6: Here we have used the density functional theory (DFT) with the GGA-PBE\napproximation to investigate the structural, mechanical, electronic, hardness,\nthermal, superconductivity and optoelectronic properties under pressure for\nmonoclinic (P21/m) and orthorhombic (Pmn21) structures of MgVH6. We have\nstudied optical properties of P21/m phase at 0 GPa and Pmn21 phase at 100 GPa\nonly (considering phase stability). Both of the phases of MgVH6 are\nthermodynamically stable. P21/m phase is mechanically stable but Pmn21 is\nmechanically unstable in our calculations for the pressures considered.\nMonoclinic (P21/m) is ductile in nature, on the other hand, orthorhombic\n(Pmn21) is brittle in nature at 100 GPa and becomes ductile for pressures in\nthe range from 125 GPa to 200 GPa. Hardness calculations indicate superhard\ncharacter of orthorhombic (Pmn21) structure at 100 GPa. The melting temperature\nof orthorhombic crystal is very high. This also agrees with the bulk modulus,\nDebye temperature, and hardness calculations. We have calculated theoretically\nthe superconducting transition temperature Tc at different pressures only for\nthe orthorhombic (Pmn21) structure following a previous study. The estimated\nvalues of transition temperatures are within 104.7 K to 26.1 K in the pressure\nrange from 100 GPa to 200 GPa. MgVH6, in both the structures, are elastically\nand optically anisotropic."
    },
    {
        "anchor": "Tunneling Spectroscopy of Graphene and related Reconstructions on\n  SiC(0001): The 5x5, 6rt(3)x6rt(3)-R30deg, and graphene-covered 6rt(3)x6rt(3)-R30deg\nreconstructions of the SiC(0001) surface are studied by scanning tunneling\nmicroscopy and spectroscopy. For the 5x5 structure a rich spectrum of surface\nstates is obtained, with one state in particular found to be localized on top\nof structural protrusions (adatoms) observed on the surface. Similar spectra\nare observed on the bare 6rt(3)x6rt(3)-R30deg reconstruction, and in both cases\nthe spectra display nearly zero conductivity at the Fermi-level. When graphene\ncovers the 6rt(3)x6rt(3)-R30deg surface the conductivity at the Fermi-level\nshows a marked increase, and additionally the various surface state peaks seen\nin the spectrum shift in energy and fall in intensity. The influence of the\noverlying graphene on the electronic properties of the interface is discussed,\nas are possible models for the interface structure.",
        "positive": "Molecular Motor Constructed from a Double-Walled Carbon Nanotube Driven\n  by Axially Varying Voltage: A new molecular motor is conceptually constructed from a double-walled carbon\nnanotube (DWNT) consisting of a long inner single-walled carbon nanotube (SWNT)\nand a short outer SWNT with different chirality. The interaction between inner\nand outer tubes is the sum of the Lennard-Jones potentials between carbon atoms\nin inner tube and those in outer one. Within the framework of\nSmoluchowski-Feynman ratchet, it is theoretically shown that this system in an\nisothermal bath will exhibit a unidirectional rotation in the presence of a\nvarying axial electrical voltage."
    },
    {
        "anchor": "Solid Source Metal-Organic Molecular Beam Epitaxy of Epitaxial RuO2: A seemingly simple oxide with a rutile structure, RuO2 has been shown to\npossess several intriguing properties ranging from strain-stabilized\nsuperconductivity to a strong catalytic activity. Much interest has arisen\nsurrounding the controlled synthesis of RuO2 films but, unfortunately,\nutilizing atomically-controlled deposition techniques like molecular beam\nepitaxy (MBE) has been difficult due to the ultra-low vapor pressure and low\noxidation potential of Ru. Here, we demonstrate the growth of epitaxial,\nsingle-crystalline RuO2 films on different substrate orientations using the\nnovel solid-source metal-organic (MO) MBE. This approach circumvents these\nissues by supplying Ru using a pre-oxidized solid metal-organic precursor\ncontaining Ru. High-quality epitaxial RuO2 films with bulk-like\nroom-temperature resistivity of 55 micro-ohm-cm were obtained at a substrate\ntemperature as low as 300 C. By combining X-ray diffraction, transmission\nelectron microscopy, and electrical measurements, we discuss the effect of\nsubstrate temperature, orientation, film thickness, and strain on the structure\nand electrical properties of these films. Our results illustrating the use of\nnovel solid-source MOMBE approach paves the way to the atomic-layer controlled\nsynthesis of complex oxides of stubborn metals, which are not only difficult to\nevaporate but also hard to oxidize.",
        "positive": "Electronic states and magnetic structure at the Co3O4 (110) surface: a\n  first principles study: Tricobalt tetraoxide (Co3O4) is an important catalyst and Co3O4(110) is a\nfrequently exposed surface in Co3O4 nanomaterials. We employed\nDensity-functional theory with on-site Coulomb repulsion U term to study the\natomic structures, energetics, magnetic and electronic properties of the two\npossible terminations, A and B, of this surface. These calculations predict A\nas the stable termination in a wide range of oxygen chemical potentials,\nconsistent with recent experimental observations. The Co3+ ions do not have a\nmagnetic moment in the bulk, but become magnetic at the surface, which leads to\nsurface magnetic orderings different from the one in the bulk. Surface\nelectronic states are present in the lower half of the bulk band gap and cause\npartial metallization of both surface terminations. These states are\nresponsible for the charge compensation mechanism stabilizing both polar\nterminations. The computed critical thickness for polarity compensation is 4\nlayers."
    },
    {
        "anchor": "First-principles embedded-cluster calculations of the neutral and\n  charged oxygen vacancy at the rutile TiO$_2$(110) surface: We perform full-potential screened-hybrid density-functional theory (DFT)\ncalculations to compare the thermodynamic stability of neutral and charged\nstates of the surface oxygen vacancy at the rutile TiO$_2$(110) surface.\nSolid-state (QM/MM) embedded-cluster calculations are employed to account for\nthe strong TiO$_2$ polarization response to the charged defect states. Similar\nto the situation for the bulk O vacancy, the +2 charge state $V_{\\rm O}^{2+}$\nis found to be energetically by far most stable. Only for Fermi-level positions\nvery close to the conduction band, small polarons may at best be trapped by the\ncharged vacancy. The large decrease of the $V_{\\rm O}^{2+}$ formation energy\nwith decreasing Fermi-level position indicates strongly enhanced surface O\nvacancy concentrations for $p$-doped samples.",
        "positive": "A short-range structural insight into lithium substituted barium\n  vanadate glasses using Raman and EPR spectroscopy as probes: We present a corroborative study of structural characterization of lithium\nsubstituted barium vanadate glasses using Raman and Electron Paramagnetic\nResonance (EPR) spectroscopy. Investigation of the thermal and physical\nproperties of these glasses showed a gradual increase in the concentration of\nnon-bridging oxygen. Raman and EPR analysis gave an insight into the changing\nstructure of the glasses. Both the spectroscopic techniques confirmed that\nvanadium is present in the glasses as distorted VO6 octahedra. From the\nanalysis of both spectroscopic techniques, it is proposed that the lithium ion\nprefers to occupy planar positions of the VO6 octahedra thus reducing the\ntetragonal distortion and making the environment around the network forming\nunit in the glass matrix more homogenous as we increase lithium content. The\nconcentration of V4+ showed a non-monotonic variation with an increase in Li2O\nas indicated by Raman studies and confirmed by EPR which indicates a structural\nchange in the distorted VO6 octahedra."
    },
    {
        "anchor": "Intercalant-independent transition temperature in superconducting black\n  phosphorus: Research on black phosphorus (BP) has been experiencing a renaissance over\nthe last few years, after the demonstration that few-layer BP exhibits high\ncarrier mobility and a thickness-dependent band gap. For a long time, bulk BP\nis also known to be a superconductor under high pressure exceeding 10 GPa. The\nsuperconductivity is due to a structural transformation into another allotrope\nof phosphorous and accompanied by a semiconductor-metal transition. No\nsuperconductivity could be achieved for BP itself (that is, in its normal\northorhombic form) despite several attempts reported in the literature. Here we\ndescribe successful intercalation of BP by several alkali metals (Li, K, Rb,\nCs) and alkali-earth Ca. All the intercalated compounds are found to be\nsuperconducting, exhibiting the same (within our experimental accuracy)\ncritical temperature of 3.8+-0.1 K and practically identical characteristics in\nthe superconducting state. Such universal superconductivity, independent of the\nchemical composition, is highly unusual. We attribute it to intrinsic\nsuperconductivity of heavily-doped individual phosphorene layers, while the\nintercalated layers of metal atoms mostly play a role of charge reservoirs.",
        "positive": "Heavy-hole band splitting observed in mobility spectrum of p-type InAs\n  grown on GaAs substrate: High quality berylium doped InAs layer grown by MBE on GaAs substrate has\nbeen examined via magnetotransport measurements and high resolution\nquantitative mobility spectrum analysis in the range from 5 to 300 K and up to\n15 T magnetic field. The layer homogenity and dopant concentration has been\nproofed via HR-SIMS. The results shew four channel conductivity and essential\nsplitting of the most populated holelike channel below 55 K. The multilayer\nmodel concluded from the QMSA results has been compared with nextnano\nsimulation."
    },
    {
        "anchor": "Thon rings from amorphous ice and implications of beam-induced Brownian\n  motion in single particle electron cryo-microscopy: We have recorded dose-fractionated electron cryo-microscope images of thin\nfilms of pure flash-frozen amorphous ice and pre-irradiated amorphous carbon on\na Falcon~II direct electron detector using 300 keV electrons. We observe Thon\nrings \\cite{Thon1966} in both the power spectrum of the summed frames and the\nsum of power spectra from the individual frames. The Thon rings from amorphous\ncarbon images are always more visible in the power spectrum of the summed\nframes whereas those of amorphous ice are more visible in the sum of power\nspectra from the individual frames. This difference indicates that while\npre-irradiated carbon behaves like a solid during the exposure, amorphous ice\nbehaves like a fluid with the individual water molecules undergoing\nbeam-induced motion. Using the measured variation in the power spectra\namplitude with number of electrons per image we deduce that water molecules are\nrandomly displaced by mean squared distance of $\\sim$ 1.1 \\AA$^{2}$ for every\nincident 300 keV e$^{-}$/\\AA$^2$. The induced motion leads to an optimal\nexposure with 300 keV electrons of 4.0 e$^{-}$/\\AA$^2$ per image with which to\nsee Thon rings centred around the strong 3.7{\\AA} scattering peak from\namorphous ice. The beam-induced movement of the water molecules generates\npseudo-Brownian motion of embedded macromolecules. The resulting blurring of\nsingle particle images contributes an additional term, on top of that from\nradiation damage, to the minimum achievable B-factor for macromolecular\nstructure determination.",
        "positive": "The (3$\\times$3)-SiC-($\\bar{1}\\bar{1}\\bar{1}$) Reconstruction: Atomic\n  Structure of the Graphene Precursor Surface from a Large-Scale\n  First-Principles Structure Search: Silicon carbide (SiC) is an excellent substrate for growth and manipulation\nof large scale, high quality epitaxial graphene. On the carbon face (the\n($\\bar{1}\\bar{1}\\bar{1}$) or $(000\\bar{1}$) face, depending on the polytype),\nthe onset of graphene growth is intertwined with the formation of several\ncompeting surface phases, among them a (3$\\times$3) precursor phase suspected\nto hinder the onset of controlled, near-equilibrium growth of graphene. Despite\nmore than two decades of research, the precise atomic structure of this phase\nis still unclear. We present a new model of the\n(3$\\times$3)-SiC-($\\bar{1}\\bar{1}\\bar{1}$) reconstruction, derived from an {\\it\nab initio} random structure search based on density functional theory including\nvan der Waals effects. The structure consists of a simple pattern of five Si\nadatoms in bridging and on-top positions on an underlying, C-terminated\nsubstrate layer, leaving one C atom per (3$\\times$3) unit cell formally\nunsaturated. Simulated scanning tunneling microscopy (STM) images are in\nexcellent agreement with previously reported experimental STM images."
    },
    {
        "anchor": "Empirical potential study of phonon transport in graphitic ribbon: The thermal properties of graphitic ribbon are investigated based on\nBrenner's empirical potential. The reliability and usefulness of the empirical\npotential to address the thermal properties of covalent-bonded carbon\nnanostructures are verified through a comparison of phonon dispersion relations\nand the density of states of carbon nanotubes with first-principles\ncalculations. The analysis reveals unique edge-phonon states that are highly\nlocalized at edge carbon atoms of both armchair and zigzag ribbons. Applying\nthe phonon dispersion relations to the Landauer formula of phonon transport,\nthe quantization and universal features of the low-temperature thermal\nconductance of graphitic ribbon are elucidated, and it is found that the width\nof the quantization plateau in the low-temperature region is inversely\nproportional to the ribbon width.",
        "positive": "Optical contrast and refractive index of natural van der Waals\n  heterostructure nanosheets of franckeite: We study mechanically exfoliated nanosheets of franckeite by quantitative\noptical microscopy. The analysis of transmission mode and epi-illumination mode\noptical microscopy images provides a rapid method to estimate the thickness of\nthe exfoliated flakes at first glance. A quantitative analysis of the optical\ncontrast spectra by means of micro-reflectance allows one to determine the\nrefractive index of franckeite in a broad range of the visible spectrum through\na fit of the acquired spectra to a Fresnel law based model."
    },
    {
        "anchor": "Simple self-gettering differential-pump for minimizing source oxidation\n  in oxide-MBE environment: Source oxidation of easily oxidizing elements such as Ca, Sr, Ba, and Ti in\nan oxidizing ambient leads to their flux instability and is one of the biggest\nproblems in the multi-elemental oxide Molecular Beam Epitaxy technique. Here we\nreport a new scheme that can completely eliminate the source oxidation problem:\na self-gettering differential pump using the source itself as the pumping\nmedium. The pump simply comprises a long collimator mounted in front of the\nsource in extended port geometry. With this arrangement, the oxygen partial\npressure near the source was easily maintained well below the source oxidation\nregime, resulting in a stabilized flux, comparable to that of an\nultra-high-vacuum environment. Moreover, this pump has a self-feedback\nmechanism that allows a stronger pumping effectiveness for more easily\noxidizing elements, which is a desired property for eliminating the source\noxidation problem.",
        "positive": "First Principles Assessment of CdTe as a Tunnel Barrier at the\n  $\\mathbf\u03b1$-Sn/InSb Interface: Majorana zero modes, with prospective applications in topological quantum\ncomputing, are expected to arise in superconductor/semiconductor interfaces,\nsuch as $\\beta$-Sn and InSb. However, proximity to the superconductor may also\nadversely affect the semiconductor's local properties. A tunnel barrier\ninserted at the interface could resolve this issue. We assess the wide band gap\nsemiconductor, CdTe, as a candidate material to mediate the coupling at the\nlattice-matched interface between $\\alpha$-Sn and InSb. To this end, we use\ndensity functional theory (DFT) with Hubbard U corrections, whose values are\nmachine-learned via Bayesian optimization (BO) [npj Computational Materials 6,\n180 (2020)]. The results of DFT+U(BO) are validated against angle resolved\nphotoemission spectroscopy (ARPES) experiments for $\\alpha$-Sn and CdTe. For\nCdTe, the z-unfolding method [Advanced Quantum Technologies, 5, 2100033 (2022)]\nis used to resolve the contributions of different $k_z$ values to the ARPES. We\nthen study the band offsets and the penetration depth of metal-induced gap\nstates (MIGS) in bilayer interfaces of InSb/$\\alpha$-Sn, InSb/CdTe, and\nCdTe/$\\alpha$-Sn, as well as in tri-layer interfaces of InSb/CdTe/$\\alpha$-Sn\nwith increasing thickness of CdTe. We find that 16 atomic layers (3.5 nm) of\nCdTe can serve as a tunnel barrier, effectively shielding the InSb from MIGS\nfrom the $\\alpha$-Sn. This may guide the choice of dimensions of the CdTe\nbarrier to mediate the coupling in semiconductor-superconductor devices in\nfuture Majorana zero modes experiments."
    },
    {
        "anchor": "A multi-objective optimization procedure to develop\n  modified-embedded-atom-method potentials: an application to magnesium: We have developed a multi-objective optimization (MOO) procedure to construct\nmodified-embedded-atom-method (MEAM) potentials with minimal manual fitting.\nThis procedure has been applied successfully to develop a new MEAM potential\nfor magnesium. The MOO procedure is designed to optimally reproduce multiple\ntarget values that consist of important materials properties obtained from\nexperiments and first-principles calculations based on density-functional\ntheory (DFT). The optimized target quantities include elastic constants,\ncohesive energies, surface energies, vacancy formation energies, and the forces\non atoms in a variety of structures. The accuracy of the new potential is\nassessed by computing several material properties of Mg and comparing them with\nthose obtained from other potentials previously published. We found that the\npresent MEAM potential yields a significantly better overall agreement with DFT\ncalculations and experiments.",
        "positive": "Implications of Coordination Chemistry to Cationic Interactions in\n  Honeycomb Layered Nickel Tellurates: Honeycomb layered tellurates represent a burgeoning class of multi-functional\nmaterials with fascinating crystal-structural versatility and a rich\ncomposition space. Despite their multifold capabilities, their compositional\ndiversity remains underexplored due to complexities in experimental design and\nsyntheses. Thus, in a bid to expand this frontier and derive relevant insights\ninto allowed metastable compositions, we employ a density functional theory\n($\\rm DFT$) approach to predict $in$ $silico$ the crystal structures of new\nhoneycomb layered tellurates embodied by the composition, $A\\rm_2 Ni_2TeO_6$\n($A$ = alkali, hydrogen or coinage-metal cations). Here, alkali-metal atoms\nwith vastly larger radii than $\\rm K$ ($\\rm Rb$ and $\\rm Cs$) are found to\nengender a prismatic coordination with the oxygen atoms from the honeycomb\nslabs whilst coinage-metal atoms ($\\rm Ag$, $\\rm Au$ and $\\rm Cu$) display a\npropensity for linear coordination. Further, $\\rm H_2 Ni_2TeO_6$ is found to\nalso render a linear coordination wherein the hydrogen atom preferentially\nestablishes a stronger coordination with one of the oxygen atoms to form\nhydroxyl groups. All $A$ cations in the studied $A\\rm_2 Ni_2TeO_6$ compositions\nform a honeycomb lattice. Conclusions on the possibility of a monolayer-bilayer\nphase transition in coinage metal atom tellurates can be drawn by considering\nthe implications of conformal symmetry of the cation honeycomb lattice and\nmetallophilicity. This work not only propounds new honeycomb layered tellurate\ncompositions but also provides novel insight into the rational design of\nmultifunctional materials for applications ranging from energy storage,\ncatalysis and optics to analogue condensed matter systems of gravity."
    },
    {
        "anchor": "A Superlens Based on Metal-Dielectric Composites: Pure noble metals are typically considered to be the materials of choice for\na near-field superlens that allows subwavelength resolution by recovering both\npropagating and evanescent waves. However, a superlens based on bulk metal can\noperate only at a single frequency for a given dielectric host. In this Letter,\nit is shown that a composite metal-dielectric film, with an appropriate metal\nfilling factor, can operate at practically any desired wavelength in the\nvisible and near-infrared ranges. Theoretical analysis and simulations verify\nthe feasibility of the proposed lens.",
        "positive": "Oxygen-vacancy-related relaxation and scaling behaviors of\n  Bi0.9La0.1Fe0.98Mg0.02O3 (La,Mg-codoped BiFeO3) ferroelectric thin film: Oxygen-vacancies-related dielectric relaxation and scaling behaviors of\nBi0.9La0.1Fe0.98Mg0.02O3 (BLFM) thin film have been investigated by\ntemperature-dependent impedance spectroscopy from 40 oC up to 200 oC. We found\nthat hopping electrons and single-charged oxygen vacancies (VO.) coexist in the\nBLFM thin film and make contribution to dielectric response of grain and grain\nboundary respectively. The activation energy for VO. is shown to be 0.94 eV in\nthe whole temperature range investigated, whereas the distinct activation\nenergies for electrons are 0.136 eV below 110oC and 0.239 eV above 110oC in\nassociation with hopping along the Fe2+- VO.-Fe3+ chain and hopping between\nFe2+-Fe3+, respectively, indicating different hopping processes for electrons.\nMoreover, it has been found that hopping electrons is in form of long rang\nmovement, while localized and long range movement of oxygen vacancies coexist\nin BLFM film. The Cole-Cole plots in modulus formalism show a poly-dispersive\nnature of relaxation for oxygen vacancies and a unique relaxation time for\nhopping electrons. The scaling behavior of modulus spectra further suggests\nthat the distribution of relaxation times for oxygen vacancies is temperature\nindependent."
    },
    {
        "anchor": "How well do Car-Parrinello simulations reproduce the Born-Oppenheimer\n  surface ? Theory and Examples: We derive an analytic expression for the average difference between the\nforces on the ions in a Car-Parrinello simulation and the forces obtained at\nthe same ionic positions when the electrons are at their ground state. We show\nthat for common values of the fictitious electron mass, a systematic bias may\naffect the Car-Parrinello forces in systems where the electron-ion coupling is\nlarge. We show that in the limit where the electronic orbitals are rigidly\ndragged by the ions the difference between the two dynamics amounts to a\nrescaling of the ionic masses, thereby leaving the thermodynamics intact. We\nstudy the examples of crystalline magnesium oxide and crystalline and molten\nsilicon. We find that for crystalline silicon the errors are very small. For\ncrystalline MgO the errors are very large but the dynamics can be quite well\ncorrected within the rigid-ion model. We conclude that it is important to\ncontrol the effect of the electron mass parameter on the quantities extracted\nfrom Car-Parrinello simulations.",
        "positive": "Non-circular skyrmion and its anisotropic response in thin films of\n  chiral magnets under tilted magnetic field: We study the equilibrium and dynamical properties of skyrmions in thin films\nof chiral magnets with oblique magnetic field. The shape of an individual\nskyrmion is non-circular and the skyrmion density decreases with the tilt angle\nfrom the normal of films. As a result, the interaction between two skyrmions\ndepends on the relative angle between them in addition to their separation. The\ntriangular lattice of skyrmions under a perpendicular magnetic field is\ndistorted into a centered rectangular lattice for a tilted magnetic field. For\na low skyrmion density, skyrmions form a chain like structure. The dynamical\nresponse of the non-circular skyrmions depends on the direction of external\ncurrents."
    },
    {
        "anchor": "Anomalous electrical conductivity in rapidly crystallized\n  Cu${}_{50-x}$Zr${}_{x}$ (x = 50 - 66.6) alloys: Cu${}_{50-x}$Zr${}_{x}$ (x = 50, 54, 60 and 66.6) polycrystalline alloys were\nprepared by arc-melting. The crystal structure of the ingots has been examined\nby X-ray diffraction. Non-equilibrium martensitic phases with monoclinic\nstructure were detected in all the alloys except Cu${}_{33.4}$Zr${}_{66.6}$.\nTemperature dependencies of electrical resistivity in the temperature range of\nT = 4 - 300 K have been measured as well as room temperature values of Hall\ncoefficients and thermal conductivity. Electrical resistivity demonstrates\nanomalous behavior. At the temperatures lower than 20 K, their temperature\ndependencies are non-monotonous with pronounced minima. At elevated\ntemperatures they have sufficiently non-linear character which cannot be\ndescribed within framework of the standard Bloch--Gr\\\"{u}neisen model. We\npropose generalized Bloch--Gr\\\"{u}neisen model with variable Debye temperature\nwhich describes experimental resistivity dependencies with high accuracy. We\nfound that both the electrical resistivity and the Hall coefficients reveal\nmetallic-type conductivity in the Cu-Zr alloys. The estimated values of both\nthe charge carrier mobility and the phonon contribution to thermal and electric\nconductivity indicate the strong lattice defects and structure disorder.",
        "positive": "Investigation into the nature behind the interesting half levitation\n  behavior of claimed superconductor LK-99: A recent article published by Lee et.al. claimed to have successfully\nachieved superconductivity at room temperature (RT) has become a topical issue.\nBesides the research paper, Lee and his team provided a demonstration video of\nLK-99 half levitating (HL) on a magnet. Such interesting HL appearance has\ndrawn tremendous sensation both in academia and the network. However, the true\nidentity of LK-99 still remains unclear, i.e., whether the HL behavior can\nnecessarily indicate the diamagnetism behavior of the sample. Here, we\nfabricated our own LK-99 samples following the procedures reported by Lee et\nal. We found quite a few sample pieces showing the typical HL that is similar\nto those reported. Meanwhile, oxidation during the sample preparation was found\nto deleterious to acquiring HL in the sample, while furnace cooling or water\nquenching in the last step revealed little effect. However, our careful\nobservations indicated that those HL pieces are more likely simple\nferromagnetic. Then we conducted a comprehensive study on the behavior patterns\nof typical diamagnetism and ferromagnetic substances interacting with a\nNd2Fe14B magnet, and provided instructions to distinguish the characteristics\nbetween ferromagnetic and diamagnetic to prevent misunderstanding of LK-99 like\nlevitation behavior."
    },
    {
        "anchor": "Ab initio study on the stability and elasticity of brucite: Brucite (Mg(OH)$_2$) is a mineral of great interest owing to its various\napplications and roles in geological processes. Its structure, behavior under\ndifferent conditions, and unique properties have been the subject of numerous\nstudies and persistent debate. As a stable hydrous phase in subduction zones,\nits elastic anisotropy can significantly contribute to the seismological\nproperties of these regions. We performed ab initio calculations to investigate\nbrucite's stability, elasticity, and acoustic velocities. We tested several\nexchange-correlation functionals and managed to obtain stable phonons for the\nP$\\bar{3}$ phase with r$^2$SCAN for the first time at all relevant pressures up\nto the mantle transition zone. We show that r$^2$SCAN performs very well in\nbrucite, reproducing the experimental equation of state and several key\nstructure parameters related to hydrogen positions. The room temperature\nelasticity results in P$\\bar{3}$ reproduces the experimental results at ambient\npressure. These results, together with the stable phonon dispersion of\nP$\\bar{3}$ at all relevant pressures, indicate P$\\bar{3}$ is the stable\ncandidate phase not only at elevated pressures but also at ambient conditions.\nThe success of r$^2$SCAN in brucite, suggests this functional should be\nsuitable for other challenging layer-structured minerals, e.g., serpentines, of\ngreat geophysical significance.",
        "positive": "Drastic pressure effect on the extremely large magnetoresistance in\n  WTe2: quantum oscillation study: The quantum oscillations of the magnetoresistance under ambient and high\npressure have been studied for WTe$_2$ single crystals, in which extremely\nlarge magnetoresistance was discovered recently. By analyzing the Shubnikov-de\nHaas oscillations, four Fermi surfaces are identified, and two of them are\nfound to persist to high pressure. The sizes of these two pockets are\ncomparable, but show increasing difference with pressure. At 0.3 K and in 14.5\nT, the magnetoresistance decreases drastically from 1.25 $\\times$ $10^5$\\%\nunder ambient pressure to 7.47 $\\times$ $10^3$\\% under 23.6 kbar, which is\nlikely caused by the relative change of Fermi surfaces. These results support\nthe scenario that the perfect balance between the electron and hole populations\nis the origin of the extremely large magnetoresistance in WTe$_2$."
    },
    {
        "anchor": "Enhancement of the response of non-uniform resonance modes of a\n  nanostructure in the Picoprobe microwave-current injection ferromagnetic\n  resonance: The non-uniform standing spin-wave modes in thin magnetic films and\nnanostructures provide important information about surfaces and buried\ninterfaces. Very often they are lacking in the recorded ferromagnetic resonance\nspectra for symmetry reasons. In this work we experimentally demonstrate that\nby direct injection of microwave currents into an array of Permalloy\nnanostripes using a microscopic microwave coaxial to coplanar adaptor one can\nefficiently excite non-uniform standing spin wave modes with odd symmetry. The\nproposed method is quick and allows easy spatial mapping of magnetic properties\nwith the resolution down to 100 microns. We have validated this method using an\nexample from a periodical array of nanostripes. The results from direct current\ninjection are compared to that of microstrip-based FMR measurements.",
        "positive": "Strain, doping and electronic transport of large area monolayer MoS2\n  exfoliated on gold and transferred to an insulating substrate: Gold-assisted mechanical exfoliation currently represents a promising method\nto separate ultra-large (cm-scale) transition metal dichalcogenides (TMDs)\nmonolayers (1L) with excellent electronic and optical properties from the\nparent van der Waals (vdW) crystals. The strong interaction between $Au$ and\nchalcogen atoms is the key to achieve this nearly perfect 1L exfoliation yield.\nOn the other hand, it may affect significantly the doping and strain of 1L TMDs\nin contact with Au. In this paper, we systematically investigated the\nmorphology, strain, doping, and electrical properties of large area 1L\n$MoS_{2}$ exfoliated on ultra-flat $Au$ films ($0.16-0.21 nm$ roughness) and\nfinally transferred to an insulating $Al_{2}O_{3}$ substrate. Raman mapping and\ncorrelative analysis of the $E'$ and $A1'$ peaks positions revealed a moderate\ntensile strain ($0.2\\%$) and p-type doping ($n=-0.25 \\times 10^{13} cm^{-2}$)\nof 1L $MoS_{2}$ in contact with $Au$. Nanoscale resolution current mapping and\ncurrent-voltage (I-V) measurements by conductive atomic force microscopy\n(C-AFM) showed direct tunnelling across the 1L $MoS_{2}$ on $Au$, with a broad\ndistribution of tunnelling barrier values (from 0.7 to 1.7 eV) consistent with\nthe p-type doping of $MoS_{2}$. After the final transfer of $1L-MoS_{2}$ on\n$Al_{2}O_{3}/Si$, the strain was converted to compressive ($-0.25\\%$).\nFurthermore, an n-type doping ($n=0.5 \\times 10^{13} cm^{-2}$) was deduced by\nRaman mapping and confirmed by electrical measurements of an $Al_{2}O_{3}/Si$\nback-gated 1L $MoS_{2}$ transistor. These results provide a deeper\nunderstanding of the $Au$-assisted exfoliation mechanisms and can contribute to\nits widespread applications for the realization of novel devices and artificial\nvdW heterostructures"
    },
    {
        "anchor": "Structural evolution of granular systems: Theory: A first-principles theory is developed for the general evolution of a key\nstructural characteristic of planar granular systems - the cell order\ndistribution. The dynamic equations are constructed and solved in closed form\nfor a number of examples: dense systems undergoing progressive compaction;\ninitial dilation of very dense systems; and the approach to steady state of\ngeneral systems. It is shown that the convergence to steady state is\nexponential, except when contacts are only broken and no new contacts are made,\nin which case the approach is algebraic in time. Where no closed form solutions\nare possible, illustrative numerical solutions of the evolution are shown.\nThese show that the dynamics are sensitive to the cell event rates, which are\nprocess dependent. The formalism can be extended to other structural\ncharacteristics, paving the way to a general theory of structural organisation\nof granular systems, parameterised by the contact event rates.",
        "positive": "Finding the stable structures of W$_x$N$_1$$_-$$_x$ with an\n  $ab$$-$$initio$ high-throughput approach: Using density functional theory calculations, many researchers have predicted\nthat various tungsten-nitride compounds WN$_x$ ($x$ > 1) will be\n\"ultra-compressible\" or \"superhard\", $i.e.$ as hard as or harder than diamond.\nThese compounds are predicted to have large bulk and shear moduli (> 200 GPa)\nand to be elastically and vibrationally stable.\n  Compounds with such desirable properties must be energetically stable against\ndecomposition into other compounds. This stability can only be found after the\ndetermination of the convex hull for W$_x$N$_1$$_-$$_x$ lines which connect the\nlowest enthalpy structures as a function of composition. The phase diagram of\nthe W-N structure is uncertain, both experimentally and computationally.\nComplex van der Waals forces play a significant role in determining the\nstructure of solid N$_2$.\n  Here we use high-throughput calculations to map out the convex hull and other\nlow energy structures for the W-N system. We find that the ground state of the\nsystem is the NbO structure, and that the WN$_2$ structures found by Wang $et$\n$al$. are also stable when the van der Waals forces are neglected. Other\nproposed structures are above the convex hull of the W-N system. We show how\nthe choice of density functional influences the shape of the curve and the\nstructures that form the hull. In nitrogen-rich compounds, the choice of\nfunctional can dramatically change the structural parameters and mechanical\nbehavior. Using any of the functionals, the bulk and shear moduli of the NbO\nphase are comparable to the WN$_x$ compounds that have been claimed to be\nultra-compressible for superhard."
    },
    {
        "anchor": "Remarkably low-energy one-dimensional fault line defects in\n  single-layered phosphorene: Systematic engineering of atomic-scale low-dimensional defects in\ntwo-dimensional nanomaterials is a promising way to modulate the electronic\nproperties of these nanomaterials. Defects at interfaces such as grain\nboundaries and line defects can often be detrimental to technologically\nimportant nanodevice operations and thus a fundamental understanding of how\nsuch one-dimensional defects may have an influence on its physio-chemical\nproperties is pivotal to optimizing their device performance. Of late,\ntwo-dimensional phosphorene has attracted much attention due to its high\ncarrier mobility and good mechanical flexibility. In this study, using\ndensity-functional theory, we investigate the temperature-dependent energetics\nand electronic structure of a single-layered phosphorene with various fault\nline defects. We have generated different line defect models based on a fault\nmethod, rather than the conventional rotation method. This has allowed us to\nstudy and identify new low-energy line defects, and we show how these\nlow-energy line defects could well modulate the electronic band gap energies of\nsingle-layered two-dimensional phosphorene -- offering a range of metallic to\nsemiconducting properties in these newly proposed low-energy line defects in\nphosphorene.",
        "positive": "Self-Assembly in the Growth of Precious Opal: It is proposed that primary nucleation of amorphous microspherulites of\nhydrated silica in natural proto-precious-opal can be followed by a long range\nsuperlattice ordering process by means of electrostatic self-assembly.\nNecessary conditions in the thermodynamics are a high surface charge density on\nmicrospherulite surfaces, a long Debye length and an appropriate number density\nof nucleation centres. A further chemical requirement is a high alkaline\nenvironmental pH from 9 to 10. It is also proposed that the characteristic\nconcentric spherical shell-like structure of spherulites, centred on primary\nnuclei, are due to sequential deposition of intrinsic salts which precipitate\nout when the corresponding solubility limits in the liquid are successively\nexceeded. It can be that the better-known sedimentation of microspherulites\nunder gravity only plays part in the final stabilization period of overall\ngrowth."
    },
    {
        "anchor": "Ordering and phonons in Ba$_3$CaNb$_{2}$O$_9$ complex perovskite: In this work we performed a detailed investigation about ordering in \\bcn\nperovskite. The sintering temperature and time were changed to obtain samples\nwith different ordering. The order parameters were probed by Raman spectroscopy\nbased on a partial disordered model. To use the partial disordered model\ncorrectly we performed {\\it ab initio} calculations in \\bcn to assign the\noptical phonons. The results showed that sintering temperature improves order\nwhile sintering time is not so efficient to promote order.",
        "positive": "Two-Stage Formation Model and Helicity of Gold Nanowires: A model for formation of helical multishell gold nanowires is proposed and is\nconfirmed with the quantum mechanical molecular dynamics simulations. The model\ncan explain the magic number of the helical gold nanowires in the multishell\nstructure. The reconstruction from ideal non-helical to realistic helical\nnanowires consists of two stages: dissociations of atoms on the outermost shell\nfrom atoms on the inner shell and slip deformations of atom rows generating\n(111)-like structure on the outermost shell. The elementary processes are\ngoverned by competition between energy loss and gain by s- and d-electrons\ntogether with the width of the d-band. The possibility for the helical\nnanowires of platinum, silver and copper is discussed."
    },
    {
        "anchor": "Carbon Nanoscrolls at High Impacts: A Molecular Dynamics Investigation: The behavior of nanostructures under high strain-rate conditions has been\nobject of interest in recent years. For instance, recent experimental\ninvestigations showed that at high velocity impacts carbon nanotubes can unzip\nresulting into graphene nanoribbons. Carbon nanoscrolls (CNS) are among the\nstructures whose high impact behavior has not yet been investigated. CNS are\ngraphene membranes rolled up into papyrus-like structures. Their unique\nopen-ended topology leads to properties not found in close-ended structures,\nsuch as nanotubes. Here we report a fully atomistic reactive molecular dynamics\nstudy on the behavior of CNS colliding at high velocities against solid\ntargets. Our results show that the velocity and scroll axis orientation are key\nparameters to determine the resulting formed nanostructures after impact. The\nrelative orientation of the scroll open ends and the substrate is also very\nimportant. We observed that for appropriate velocities and orientations, the\nnanoscrolls can experience large structural deformations and large-scale\nfractures. We have also observed unscrolling (scrolls going back to planar or\nquasi-planar graphene membranes), unzip resulting into nanoribbons, and\nsignificant reconstructions from breaking and/or formation of new chemical\nbonds. Another interesting result was that if the CNS impact the substrate with\ntheir open ends, for certain velocities, fused scroll walls were observed.",
        "positive": "Low cost Ge/Si virtual substrate through dislocation trapping by\n  nanovoids: A low-cost method to reduce the threading disloca-tions density (TDD) in\nrelaxed germanium (Ge) epilayers grown on silicon (Si) substrates is presented.\nGe/Si sub-strate was treated with post epitaxial process to create a region\nwith a high density of nanovoids in Ge layer which act as a barrier for\nthreading dislocations propagation ."
    },
    {
        "anchor": "Electrochemistry of thin films with operando grazing incidence X-ray\n  scattering: bypassing electrolyte scattering for high fidelity time resolved\n  studies: Electroactive polymer thin films undergo repeated reversible structural\nchange during operation in electrochemical applications. While synchrotron\nX-ray scattering is powerful for the characterization of stand-alone and\nex-situ organic thin films, in situ structural characterization has been\nunderutilized--in large part due to complications arising from supporting\nelectrolyte scattering. This has greatly hampered the development of\napplication relevant structure property relationships. Therefore, we have\ndeveloped a new methodology for in situ and operando X-ray characterization\nthat separates the incident and scattered X-ray beam path from the electrolyte.\nAs a proof of concept, we demonstrate the in situ structural changes of\nweakly-scattering, organic mixed ionic-electronic conductor thin films in an\naqueous electrolyte environment, enabling access to previously unexplored\nchanges in the pi-pi peak and diffuse scatter in situ, while capturing the\nsolvent swollen thin film structure which was inaccessible in previous ex situ\nstudies. These in situ measurements improve the sensitivity to structural\nchanges, capturing minute changes not possible ex situ, and have multimodal\npotential such as combined Raman measurements that also serve to validate the\ntrue in situ/operando conditions of the cell. Finally, we examine new\ndirections enabled by this operando cell design and compare state of the art\nmeasurements.",
        "positive": "Framework for additive manufacturing of porous Inconel 718 for\n  electrochemical applications: Porous electrodes were developed using laser powder bed fusion of Inconel 718\nlattice structures and electrodeposition of a porous nickel catalytic layer.\nLaser energy densities of ~83-333 J/m were used to fabricate ~500 um thick\nelectrodes made of body centered cubic unit cells of 200-500 um and strut\nthicknesses of 100-200 um. Unit cells of 500 um and strut thickness of 200 um\nwere identified as optimum. Despite small changes in feature sizes by the\nenergy input, the porosity of >50% and pore size of ~100 um did not change. In\na subsequent step, we used nickel electrodeposition to create smaller scale\npores on the electrode. The electrochemical performance of the electrodes for\nhydrogen/oxygen evolution reaction (HER/OER) was evaluated in a three-electrode\nsetup. For HER, a much larger maximum current density of ~ -372 mA/cm2 at a\nless negative potential of ~-0.4 V vs RHE (potential against reversible\nhydrogen electrode) was obtained in the nickel-coated samples, as compared to\n-240 mA/cm2 at ~-0.6 V in the bare one, indicating superior performance of the\ncoated sample. Conversely, OER exhibited minor performance differences upon\napplication of the coating, indicating insignificant dependence of OER to\nsurface composition and available surface."
    },
    {
        "anchor": "Strong exciton binding in quantum structures through remote dielectric\n  confinement: We propose a new type of hybrid systems formed by conventional semiconductor\nnanostructures with the addition of remote insulating layers, where the\nelectron-hole interaction is enhanced by combining quantum and dielectric\nconfinement over different length scales. Due to the polarization charges\ninduced by the dielectric mismatch at the semiconductor/insulator interfaces,\nwe show that the exciton binding energy can be more than doubled. For\nconventional III-V quantum wires such remote dielectric confinement allows\nexciton binding at room temperature.",
        "positive": "Correlation between Local Structure Distortions and Martensitic\n  Transformation in Ni-Mn-In alloys: The local structural distortions arising as a consequence of increasing Mn\ncontent in Ni_2Mn_1+xIn_1-x (x=0, 0.3, 0.4, 0.5 and 0.6) and its effect on\nmartensitic transformation have been studied using Extended X-ray Absorption\nFine Structure (EXAFS) spectroscopy. Using the room temperature EXAFS at the Ni\nand Mn K-edges in the above compositions, the changes associated with respect\nto the local structure of these absorbing atoms are compared. It is seen that\nin the alloys exhibiting martensitic transformation ($x \\ge 0.4$) there is a\nsignificant difference between the Ni-In and Ni-Mn bond lengths even in the\naustenitic phase indicating atomic volume to be the main factor in inducing\nmartensitic transformation in Ni-Mn-In Heusler alloys."
    },
    {
        "anchor": "Enhanced sensitivity of partial O-terminated H-diamond for H2S detection\n  at room temperature: The p-type surface conductivity of H-terminated diamond (HD) has opened new\npath ways to develop diamond based electronic devices, photo-catalysts,\nchemical and bio-sensors. Herein, we report on the room temperature H2S\ndetection behaviour of pristine HD and the surface modified HD films with\npartial O-termination (OHD) through ozonation. The response of the pristine HD\nand partial OHD devices that are ozonated for 30, 60 and 90 s, is found to be ~\n55, 1420, 810 and 95 % respectively, for exposing 900 ppb of H2S under ambient\natmosphere at room temperature. Here, the optimally partial OHD sensor displays\nan enhanced sensitivity by about an order of magnitude due to the catalytic\nactivity of the sparsely populated O-functional groups on HD surface. Moreover,\nthe gas sensor response is found to be higher in wet background atmospheres\nsuch as N2 and synthetic air as compared to their respective dry atmospheres.\nAlso, the response curve of these sensors exhibits a peculiar decrease in\nresistance immediately after exposure to H2S under wet background atmosphere\nwhile such oxidative behaviour is absent under dry atmospheres. Based on these\nobservations, the plausible sensing mechanism of these H-diamond based sensors\nis proposed with the concept of humidity induced H2S hydrolyzation.",
        "positive": "Dielectric screening in extended systems using the self-consistent\n  Sternheimer equation and localized basis sets: We develop a first-principles computational method for investigating the\ndielectric screening in extended systems using the self-consistent Sternheimer\nequation and localized non-orthogonal basis sets. Our approach does not require\nthe explicit calculation of unoccupied electronic states, only uses two-center\nintegrals, and has a theoretical scaling of order O(N^3). We demonstrate this\nmethod by comparing our calculations for silicon, germanium, diamond, and LiCl\nwith reference planewaves calculations. We show that accuracy comparable to\nplanewaves calculations can be achieved via a systematic optimization of the\nbasis set."
    },
    {
        "anchor": "Kinetic Control of Recombination in Organic Photovoltaics: The Role of\n  Spin: In photovoltaic diodes recombination of photogenerated electrons and holes is\na major loss process. Biological light harvesting complexes (LHCs) prevent\nrecombination via the use of cascade structures, which lead to spatial\nseparation of charge-carriers1. In contrast, the nanoscale morphology and high\ncharge densities in organic photovoltaic cells (OPVs) give a high rate of\nelectron-hole encounters, which should result in the formation of spin triplet\nexcitons, as in organic light emitting diodes (OLEDs)2. OPVs would have poor\nquantum efficiencies if every encounter lead to recombination, but\nstate-of-the-art OPVs demonstrate near-unity quantum efficiency3. Here we show\nthat this suppression of recombination can be engineered through the interplay\nbetween spin, energetics and delocalisation of electronic excitations in\norganic semiconductors. We use time-resolved spectroscopy to study a series of\nmodel, high efficiency polymer-fullerene systems in which the lowest lying\nmolecular triplet exciton (T1) (on the polymer) lies below the intermolecular\ncharge transfer state (CT). We observe the formation of T1 states following\nbimolecular recombination, indicating that encounters of spin-uncorrelated\nelectrons and holes generate CT states with both spin singlet (1CT) and spin\ntriplet (3CT) characters. We show that triplet exciton formation can be the\nmajor loss mechanism in OPVs. However, we find that even when energetically\nfavoured, the relaxation of 3CT to T1 can be strongly suppressed, via control\nover wavefunction delocalisation, allowing for the dissociation of 3CT back to\nfree changes, thereby reducing recombination and enhancing device performance.\nOur results point towards new design rules for artificial photo-conversion\nsystems, enabling the suppression of electron-hole recombination, and also for\nOLEDs, avoiding the formation of triplet states and enhancing fluorescence\nefficiency.",
        "positive": "Interfacial strain relief by periodic dislocation doublets emerging from\n  rotationally related orientation relationships of Y4Zr3O12 dispersions in\n  ferrite matrix: The trigonal/bcc orientation relationships (ORs) and their likelihood of\noccurrence are extensively studied using dispersed Y4Zr3O12nano-precipitates in\nbcc Fe matrix by means of transmission electron microscopy, image simulations,\nand a crystallographic model. Two orientation relationships related by a\nrotation:[1-20]||[111] with (21-2)||(-110) and [1-20]||[111] with\n(00-3)||(-110), are established and periodic arrays of misfit dislocation\ndoublets are identified at the strained interface in (110) for both ORs.\nFurther eighteen energetically feasible ORs in Y4Zr3O12/bcc system are deduced\nby combining stereographic projections, which include the two predominant ORs\nin this study and other ORs in literature. The orientation relationship which\ngenerates the interface with a minimum number of dislocation doublets is the\nmost frequent."
    },
    {
        "anchor": "The role of the Berry Phase in Dynamical Jahn-Teller Systems: The presence/absence of a Berry phase depends on the topology of the manifold\nof dynamical Jahn-Teller potential minima. We describe in detail the relation\nbetween these topological properties and the way the lowest two adiabatic\npotential surfaces get locally degenerate. We illustrate our arguments through\nspherical generalizations of the linear T x h and H x h cases, relevant for the\nphysics of fullerene ions. Our analysis allows us to classify all the spherical\nJahn-Teller systems with respect to the Berry phase. Its absence can, but does\nnot necessarily, lead to a nondegenerate ground state.",
        "positive": "First-principles calculations of magnetic states in pyrochlores using a\n  source-corrected exchange and correlation functional: We present a first-principles investigation of the spin-ice state in\nDy$_2$Ti$_2$O$_7$ using a magnetic source-free exchange and correlation\nfunctional, implemented in the Castep electronic-structure code. By comparing\nresults from the conventional local spin-density approximation, we show that a\nspin-ice state in Dy$_2$Ti$_2$O$_7$ can be reliably obtained by removing the\nmagnetic sources from the exchange and correlation contributions to the\npotential, and we contrast this against the computed ground states of other\nfrustrated pyrochlore magnets."
    },
    {
        "anchor": "Coupling between octahedral rotations and local polar displacements in\n  WO3/ReO3 superlattices: We model short-period superlattices of WO$_3$ and ReO$_3$ with\nfirst-principles calculations. In fully-relaxed superlattices, we observe that\noctahedral tilts about an axis in the planes of the superlattices do not\npropagate from one material, despite the presence of the corner-shared oxygen\natoms. However, we find that octahedral rotation is enhanced within WO$_3$\nlayers in cases in which strain couples with native antiferroelectric\ndisplacements of tungsten within their octahedral cages. Resulting structures\nremain antiferroelectric with low net global polarization. Thermodynamic\nanalysis reveals that superlattices with sufficiently thick ReO$_3$ layers, the\nabsolute number being three or more layers and the Re fraction $\\geq 50\\%$,\ntend to be more stable than the separated material phases and also show\nenhanced octahedral rotations in the WO$_3$ layers.",
        "positive": "Current Perpendicular-to-Plane (CPP) Magnetoresistance (MR): Measurements of Giant Magnetoresistance (GMR) in ferromagnetic/non-magnetic\n(F/N) multilayers with Current flow Perpendicular to the layer Planes\n(CPP-geometry) can give better access to the fundamental physics underlying GMR\nthan measurements with the more usual Current flow In the layer Planes (CIP\ngeometry). Because the same measuring current passes through all of the layers,\nthe CPP-MR can often be described by simpler equations that allow separation of\neffects of scattering within the bulk of the F- and N-metals and at F/N, N1/N2,\nand F/S (S = superconductor) interfaces. We first describe the parameters that\nare used to characterize the CPP-MR, the different techniques used to measure\nthese parameters, and the different types of multilayers used to control the\ntwo orientations of the magnetizations of adjacent F-layers, anti-parallel (AP)\nand parallel (P), that permit isolation of the parameters. We then detail what\nhas been learned about the parameters of bulk F-metals, of bulk N-metals, and\nof F/N, N1/N2, and F/S interfaces. Especially important are the parameters of\ninterfaces and the spin-diffusion lengths in F-metals and F-alloys, about which\nalmost nothing was known in advance. Lastly, we describe work toward CPP-MR\ndevices and studies of magnetothermoelectric effects, before summarizing what\nhas been learned and listing some items not yet understood."
    },
    {
        "anchor": "Optimization of salt concentration and Explanation of Two Peak\n  Percolation in Blend Solid Polymer Nanocomposite Films: The present paper report is focused toward the preparation of the flexible\nand freestanding blend solid polymer electrolyte films based on PEO-PVP\ncomplexed with NaPF6 by solution cast technique. The structural/morphological\nfeatures of the synthesized polymer nanocomposite films have been investigated\nin detail using X-ray diffraction, Fourier transform infra-red spectroscopy,\nfield emission scanning electron microscope, and atomic force microscopy\ntechniques. The film PEO-PVP+NaPF6 O/Na:8 exhibits highest ionic conductivity\n~5.92x10-6 S cm-1 at 40 oC and ~2.46x10-4 S cm-1 at 100 oC. The temperature\ndependent conductivity shows Arrhenius type behavior and activation energy\ndecreases with the addition of salt. The high temperature (100 oC) conductivity\nmonitoring is done for the optimized PEO-PVP+NaPF6 O/Na:8 highly conductive\nsystem and the conductivity is still maintained stable up to 160 h (approx. 7\ndays). The thermal transitions parameters were measured by the differential\nscanning calorimetry (DSC) measurements. The prepared polymer electrolyte film\ndisplays the smoother surface in addition of salt and a thermal stability up to\n300 oC............",
        "positive": "Helium-iron compounds at terapascal pressures: We investigate the binary phase diagram of helium and iron using\nfirst-principles calculations. We find that helium, which is a noble gas and\ninert at ambient conditions, forms stable crystalline compounds with iron at\nterapascal pressures. A FeHe compound becomes stable above 4 TPa, and a\nFeHe$_2$ compound above 12 TPa. Melting is investigated using molecular\ndynamics simulations, and a superionic phase with sublattice melting of the\nhelium atoms is predicted. We discuss the implications of our predicted\nhelium-iron phase diagram for interiors of giant (exo)planets and white dwarf\nstars."
    },
    {
        "anchor": "A tetragonal-to-monoclinic phase transition in a ferroelectric\n  perovskite: the structure of PbZr(0.52)Ti(0.48)O3: The perovskite-like ferroelectric system PbZr(1-x)Ti(x)O3 (PZT) has a nearly\nvertical morphotropic phase boundary (MPB) around x=0.45-0.50. Recent\nsynchrotron x-ray powder diffraction measurements by Noheda et al. [Appl. Phys.\nLett. 74, 2059 (1999)] have revealed a new monoclinic phase between the\npreviously-established tetragonal and rhombohedral regions. In the present work\nwe describe a Rietveld analysis of the detailed structure of the tetragonal and\nmonoclinic PZT phases on a sample with x= 0.48 for which the lattice parameters\nare respectively: at= 4.044 A, ct= 4.138 A, at 325 K, and am= 5.721 A, bm=\n5.708 A, cm= 4.138 A, beta= 90.496 deg., at 20K. In the tetragonal phase the\nshifts of the atoms along the polar [001] direction are similar to those in\nPbTiO3 but the refinement indicates that there are, in addition, local\ndisordered shifts of the Pb atoms of ~0.2 A perpendicular to the polar axis..\nThe monoclinic structure can be viewed as a condensation along one of the <110>\ndirections of the local displacements present in the tetragonal phase. It\nequally well corresponds to a freezing-out of the local displacements along one\nof the <100> directions recently reported by Corker et al.[J. Phys. Condens.\nMatter 10, 6251 (1998)] for rhombohedral PZT. The monoclinic structure\ntherefore provides a microscopic picture of the MPB region in which one of the\n\"locally\" monoclinic phases in the \"average\" rhombohedral or tetragonal\nstructures freezes out, and thus represents a bridge between these two phases.",
        "positive": "From molten salts to room temperature ionic liquids: Simulation studies\n  on chloroaluminate systems: An interaction potential including chloride anion polarization effects,\nconstructed from first-principles calculations, is used to examine the\nstructure and transport properties of a series of chloroaluminate melts. A\nparticular emphasis was given to the study of the equimolar mixture of\naluminium chloride with 1-ethyl-3-methylimidazolium chloride, which forms a\nroom temperature ionic liquid EMI-AlCl 4. The structure yielded by the\nclassical simulations performed within the framework of the polarizable ion\nmodel is compared to the results obtained from entirely electronic\nstructure-based simulations: An excellent agreement between the two flavors of\nmolecular dynamics is observed. When changing the organic cation EMI+ by an\ninorganic cation with a smaller ionic radius (Li+, Na+, K+), the\nchloroaluminate speciation becomes more complex, with the formation of Al2Cl 7-\nin small amounts. The calculated transport properties (diffusion coefficients,\nelectrical conductivity and viscosity) of EMI-AlCl4 are in good agreement with\nexperimental data."
    },
    {
        "anchor": "Optimal Paths for Spatially Extended Metastable Systems Driven by Noise: The least action principle is exploited as a simulation tool to find the\noptimal dynamic path for spatially extended systems driven by a small noise.\nApplications are presented for thermally activated switching of a\nspatially-extended bistable system as well as the switching dynamics of\nmagnetic thin films. The issue of nucleation versus propagation is discussed\nand the scaling for the number of nucleation events as a function of the\nterminal time and other material parameters is computed.",
        "positive": "Lifetime of Excitons in Janus Monolayer MoSSe Prepared from Exfoliated\n  MoSe_2: Janus monolayer transition metal dichalcogenides, where one of the two\nchalcogen layers is substituted with a different kind of chalcogen atoms, are\npushing the properties of two dimensional materials into new territories. Yet\nonly little is known about this new kind of material class, mainly due to the\nchallenging synthesis. In this work we propose a method to prepare high quality\nJanus MoSSe monolayers from as-exfoliated MoSe2 by thermal sulfurization. With\nthis we aim to pave a way for more exotic Janus monolayers, which have been out\nof the experimental reach thus far. The synthesized MoSSe is diligently\ncharacterized by room- and low-temperature Raman and photoluminescence\nspectroscopy, atomic force microscopy correlated with Raman mappings, and\ntime-correlated single-photon counting. The latter providing new information on\nthe lifetime of excitons in Janus MoSSe monolayers. In addition, we report an\nenhanced trion formation at low temperatures and a relatively high excitonic\ntransition energy that is indicative of less defect states and strain, and\ntherefore a high sample quality."
    },
    {
        "anchor": "The role of occupied d states in the relaxation of hot electrons in Au: We present first-principles calculations of electron-electron scattering\nrates of low-energy electrons in Au. Our full band-structure calculations\nindicate that a major contribution from occupied d states participating in the\nscreening of electron-electron interactions yields lifetimes of electrons in Au\nwith energies of $1.0-3.0 {\\rm eV}$ above the Fermi level that are larger than\nthose of electrons in a free-electron gas by a factor of $\\sim 4.5$. This\nprediction is in agreement with a recent experimental study of ultrafast\nelectron dynamics in Au(111) films (J. Cao {\\it et al}, Phys. Rev. B {\\bf 58},\n10948 (1998)), where electron transport has been shown to play a minor role in\nthe measured lifetimes of hot electrons in this material.",
        "positive": "Robust Bloch character at the band edges of hybrid halide perovskites: The high-symmetry pseudocubic init cell is often used for modelling the\nelectronic structure of halide perovskites. However, direct comparison of the\nband structure with more realistic low-symmetry phases is impeded by the zone\nfolding. We utilize a spectral density technique in order to reduce the\nsupercell band structure to a common Bloch basis. This allows us to compare the\nelectronic structure of high- and low-symmetry phases as well as investigate\neffects of structural and compositional disorder on states near to the band\nedges that govern transport, dissociation and recombination of optical\nexcitations."
    },
    {
        "anchor": "Crystalline symmetry and the melt-growth kinetics of solid-liquid\n  interface: One of the important factors governing the growth morphology of materials is\nthe interface kinetic coefficient \\mu, which is the proportionality constant\nbetween the velocity of solid-liquid interface and undercooling. We employ\nGinzburg-Landau (GL) free energy functional to derive an analytical expression\nof kinetic coefficients. The anisotropy of kinetic coefficients naturally arise\nfrom the broken symmetry at the solid-liquid interface for various crystalline\norientations. The analytical expression of kinetic coefficients is compared to\nMikheev-Chernov theory [J. Cryst. Growth 112, 591 (1991)] derived from\nhydrodynamic equations. In addition, we use equilibrium density wave profiles\nto evaluate kinetic coefficients and compare them with that from MD\nsimulations. Our results are in good agreement with Mikheev-Chernov theory and\nMD simulations and shed lights on a possible origin of anisotropy of\ninterfacial kinetics.",
        "positive": "Accurate modeling of left-handed media using finite-difference\n  time-domain method and finite-size effects of a left-handed medium slab on\n  the image quality revisited: The letter contains an important message regarding the numerical modeling of\nleft-handed media (LHM) using the finite-difference time-domain (FDTD) method\nwhich remains at the moment one of the main techniques used in studies of these\nexotic materials. It is shown that conventional implementation of the\ndispersive FDTD method leads to inaccurate description of evanescent waves in\nthe LHM. This defect can be corrected using the spatial averaging at the\ninterfaces. However, a number of results obtained using conventional FDTD\nmethod has to be reconsidered. For instance, the accurate simulation of\nsub-wavelength imaging by the finite-sized slabs of left-handed media does not\nreveal the cavity effect reported in [Phys. Rev. Lett. 92, 107404 (2004)].\nHence the finite transverse dimension of LHM slabs does not have significant\neffects on the sub-wavelength image quality, in contrary to previous\nassertions."
    },
    {
        "anchor": "Ultra-broad near-infrared photoluminescence from crystalline\n  (K-crypt)2Bi2 containing [Bi2]2- dimers: For the first time, we report that a single crystal of (K-crypt)2Bi2\ncontaining [Bi2]2+ displays ultra-broad near-infrared photoluminescence (PL)\npeaking at around 1190 nm and having a full width at the half maximum of 212\nnm, stemming from the inherent electronic transitions of [Bi2]2+.The results\nnot only add to the number of charged Bi species with luminescence, but also\ndeepen the understanding of Bi-related near-infrared emission behavior and lead\nto the reconsideration of the fundamentally important issue of Bi-related PL\nmechanisms in some material systems such as bulk glasses, fibers, and\nconventional optical crystals.",
        "positive": "A novel super-elastic carbon nanofiber with cup-stacked carbon nanocones\n  and a screw dislocation: Carbon nanofibers (NFs) have been envisioned with broad promising\napplications, such as nanoscale actuators and energy storage medium. This work\nreports for the first-time super-elastic tensile characteristics of NFs\nconstructed from a screw dislocation of carbon nanocones (NF-S). The NF-S\nexhibits three distinct elastic deformation stages under tensile, including an\ninitial homogeneous deformation, delamination, and further stretch of covalent\nbonds. The delamination process endows the NF-S extraordinary tensile\ndeformation capability, which is not accessible from its counterpart with a\nnormal cup-stacked geometry. The failure of NF-S is governed by the inner edges\nof the nanocone due to the strain concentration, leading to a common failure\nforce for NF-S with varying geometrical parameters. Strikingly, the\ndelamination process is dominated by the inner radius and the apex angle of the\nnanocone. For a fixed apex angle, the yielding strain increases remarkably when\nthe inner radius increases, which can exceed 1000%. It is also found that the\nscrew dislocation allows the nanocones flattening and sliding during\ncompression. This study provides a comprehensive understanding on the\nmechanical properties of NFs as constructed from carbon nanocones, which opens\nnew avenues for novel applications, such as nanoscale actuators."
    },
    {
        "anchor": "Thermoelectric properties of polycrystalline palladium sulfide: A suite measurements of the electrical, thermal, and vibrational properties\nare conducted on palladium sulfide (PdS) in order to investigate its\nthermoelectric performance. The tetragonal structure with the space group\n$P$42/$m$ for PdS is determined from X-ray diffraction measurement. The unique\ntemperature dependence of mobility suggests that acoustic phonons and ion\nimpurity scattering are two dominant scattering mechanisms within the compound.\nThe obtained power factor of $27$ $\\mu$Wcm$^{-1}$K$^{-2}$ at 800 K is the\nlargest value in the remaining transition-metal sulfides studied so far. The\nmaximum value of the dimensionless figure of merit is 0.33 at 800 K. The\nobserved phonon softening with temperature indicates that the reduction of the\nlattice thermal conductivity is mainly controlled by the enhanced lattice\nanharmonicity. These results indicate that the binary bulk PdS has promising\npotential to have good thermoelectrical performance.",
        "positive": "Hyperfine and quadrupole interactions for Dy isotopes in DyPc$_2$\n  molecules: Nuclear spin levels play an important role in understanding magnetization\ndynamics and implementation and control of quantum bits in lanthanide-based\nsingle-molecule magnets. We investigate the hyperfine and nuclear quadrupole\ninteractions for $^{161}$Dy and $^{163}$Dy nucleus in anionic DyPc$_2$\n(Pc=phthalocyanine) single-molecule magnets, using multiconfigurational\nab-initio methods (beyond density-functional theory) including spin-orbit\ninteraction. The two isotopes of Dy are chosen because the others have zero\nnuclear spin. Both isotopes have the nuclear spin $I=5/2$, although the\nmagnitude and sign of the nuclear magnetic moment differ from each other. The\nlarge energy gap between the electronic ground and first-excited Kramers\ndoublets, allows us to map the microscopic hyperfine and quadrupole interaction\nHamiltonian onto an effective Hamiltonian with an electronic pseudo-spin\n$S_{\\rm eff}=1/2$ that corresponds to the ground Kramers doublet. Our ab-initio\ncalculations show that the coupling between the nuclear spin and electronic\norbital angular momentum contributes the most to the hyperfine interaction and\nthat both the hyperfine and nuclear quadrupole interactions for $^{161}$Dy and\n$^{163}$Dy nucleus are much smaller than those for $^{159}$Tb nucleus in\nTbPc$_2$ single-molecule magnets. The calculated separations of the\nelectronic-nuclear levels are comparable to experimental data reported for\n$^{163}$DyPc$_2$. We demonstrate that hyperfine interaction for Dy Kramers ion\nleads to tunnel splitting (or quantum tunneling of magnetization) at zero\nfield. This effect does not occur for TbPc$_2$ single-molecule magnets. The\nmagnetic field values of the avoided level crossings for $^{161}$DyPc$_2$ and\n$^{163}$DyPc$_2$ are found to be noticeably different, which can be observed\nfrom experiment."
    },
    {
        "anchor": "Towards wafer-scale diamond nano- and quantum technologies: We investigate native nitrogen (NV) and silicon vacancy (SiV) color centers\nin commercially available, heteroepitaxial, wafer-sized, mm thick,\nsingle-crystal diamond. We observe single, native NV centers with a density of\nroughly 1 NV per $\\mu m^3$ and moderate coherence time ($T_2 = 5 \\mu s$)\nembedded in an ensemble of SiV centers. Low-temperature spectroscopy of the SiV\nzero phonon line fine structure witnesses high crystalline quality of the\ndiamond especially close to the growth surface, consistent with a reduced\ndislocation density. Using ion implantation and plasma etching, we verify the\npossibility to fabricate nanostructures with shallow color centers rendering\nour diamond material promising for fabrication of nanoscale sensing devices. As\nthis diamond is available in wafer-sizes up to $100 mm$ it offers the\nopportunity to up-scale diamond-based device fabrication.",
        "positive": "Multiferroicity and hydrogen-bond ordering in (C2H5NH3)2CuCl4 featuring\n  dominant ferromagnetic interactions: We demonstrate that ethylammonium copper chloride, (C2H5NH3)2CuCl4, a member\nof the hybrid perovskite family is an electrically polar and magnetic compound\nwith dielectric anomaly around the Curie point (247 K). We have found large\nspontaneous electric polarization below this point accompanied with a color\nchange in the sample. The system is also ferroelectric, with large remnant\npolarization (37{\\mu}C/cm2) that is comparable to classical ferroelectric\ncompounds. The results are ascribed to hydrogen-bond ordering of the organic\nchains. The coexistence of ferroelectricity and dominant ferromagnetic\ninteractions allows to relate the sample to a rare group of magnetic\nmultiferroic compounds. In such hybrid perovskites the underlying hydrogen\nbonding of easily tunable organic building blocks in combination with the 3d\ntransition-metal layers offers an emerging pathway to engineer multifuctional\nmultiferroics."
    },
    {
        "anchor": "$d^0$ half-metallic ferromagnetism in CaN and CaAs pnictides: An ab\n  initio study: Conventional magnetism occurs in systems which contain transition metals or\nrare earth ions with partially filled $d$ or $f$ shells. It is theoretically\npredicted that compounds of groups IA and IIA with IV and V, in some structural\nphases, are ferromagnetic half-metals which made them new candidates for\nspintronics applications. Employing density functional theory (DFT) we\ninvestigate magnetism in binary compounds CaN and CaAs. Regarding the structure\nof analogous magnetic materials and experimental results of CaAs synthesis, we\nhave considered two cubic structures: rocksalt (RS) and zincblende (ZB), and\nfour hexagonal structures: NiAs, wurtzite (WZ), anti-NiAs, and NaO. The\ncalculated results show that CaN in cubic, NiAs, and wurtzite structures, and\nCaAs only in zincblende phase have ferromagnetic ground states with a magnetic\nmoment of $1\\mu _B$. Electronic structure analysis of these materials indicates\nthat magnetism originates from anion $p$ states. Existence of flat $p$ bands\nand consequently high density of states at the Fermi level of magnetic\nstructures gives rise to Stoner spin splitting and spontaneous ferromagnetism.",
        "positive": "Consequences of local gauge symmetry in empirical tight-binding theory: A method for incorporating electromagnetic fields into empirical\ntight-binding theory is derived from the principle of local gauge symmetry.\nGauge invariance is shown to be incompatible with empirical tight-binding\ntheory unless a representation exists in which the coordinate operator is\ndiagonal. The present approach takes this basis as fundamental and uses group\ntheory to construct symmetrized linear combinations of discrete coordinate\neigenkets. This produces orthogonal atomic-like \"orbitals\" that may be used as\na tight-binding basis. The coordinate matrix in the latter basis includes\nintra-atomic matrix elements between different orbitals on the same atom.\nLattice gauge theory is then used to define discrete electromagnetic fields and\ntheir interaction with electrons. Local gauge symmetry is shown to impose\nstrong restrictions limiting the range of the Hamiltonian in the coordinate\nbasis. The theory is applied to the semiconductors Ge and Si, for which it is\nshown that a basis of 15 orbitals per atom provides a satisfactory description\nof the valence bands and the lowest conduction bands. Calculations of the\ndielectric function demonstrate that this model yields an accurate joint\ndensity of states, but underestimates the oscillator strength by about 20% in\ncomparison to a nonlocal empirical pseudopotential calculation."
    },
    {
        "anchor": "Spontaneous polarization and piezoelectric constants of III-V nitrides: The spontaneous polarization, dynamical Born charges, and piezoelectric\nconstants of the III-V nitrides AlN, GaN, and InN are studied ab initio using\nthe Berry phase approach to polarization in solids. The piezoelectric constants\nare found to be up 10 times larger than in conventional III-V's and II-VI's,\nand comparable to those of ZnO. Further properties at variance with those of\nconventional III-V compounds are the sign of the piezoelectric constants\n(positive as in II-VI's) and the very large spontaneous polarization.",
        "positive": "Self-learning Hybrid Monte Carlo: A First-principles Approach: We propose a novel approach called Self-Learning Hybrid Monte Carlo (SLHMC)\nwhich is a general method to make use of machine learning potentials to\naccelerate the statistical sampling of first-principles\ndensity-functional-theory (DFT) simulations. The trajectories are generated on\nan approximate machine learning (ML) potential energy surface. The trajectories\nare then accepted or rejected by the Metropolis algorithm based on DFT\nenergies. In this way the statistical ensemble is sampled exactly at the DFT\nlevel for a given thermodynamic condition. Meanwhile the ML potential is\nimproved on the fly by training to enhance the sampling, whereby the training\ndata set, which is sampled from the exact ensemble, is created automatically.\nUsing the examples of $\\alpha$-quartz crystal SiO$_2^{}$ and phonon-mediated\nunconventional superconductor YNi$_2^{}$B$_2^{}$C systems, we show that SLHMC\nwith artificial neural networks (ANN) is capable of very efficient sampling,\nwhile at the same time enabling the optimization of the ANN potential to within\nmeV/atom accuracy. The ANN potential thus obtained is transferable to ANN\nmolecular dynamics simulations to explore dynamics as well as thermodynamics.\nThis makes the SLHMC approach widely applicable for studies on materials in\nphysics and chemistry."
    },
    {
        "anchor": "Blue shifting of the A exciton peak in folded monolayer 1H-MoS2: The large family of layered transition-metal dichalcogenides is widely\nbelieved to constitute a second family of two-dimensional (2D) semiconducting\nmaterials that can be used to create novel devices that complement those based\non graphene. In many cases these materials have shown a transition from an\nindirect bandgap in the bulk to a direct bandgap in monolayer systems. In this\nwork we experimentally show that folding a 1H molybdenum disulphide (MoS2)\nlayer results in a turbostratic stack with enhanced photoluminescence quantum\nyield and a significant shift to the blue by 90 meV. This is in contrast to the\nexpected 2H-MoS2 band structure characteristics, which include an indirect gap\nand quenched photoluminescence. We present a theoretical explanation to the\norigin of this behavior in terms of exciton screening.",
        "positive": "Kinetic Monte Carlo simulations of self organized nanostructures on Ta\n  Surface Fabricated by Low Energy Ion Sputtering: Surfaces bombarded with low energy ion beams often display development of\nself assembled patterns and quasi-periodic structures. Kinetic Monte Carlo\nsimulations have been performed to describe ion sputtered Tantalum surfaces. A\nweak nonlinearity in the relaxation process has been introduced and the results\nshow that the Positive Schwoebel barrier, produced by the nonlinear\nHamiltonian, is necessary in describing ion bombarded Tantalum surfaces.\nFurthermore, their scaling exponents suggest presence of a class other than\nKPZ."
    },
    {
        "anchor": "Transport properties of beta-Ga2O3 Nanoparticles embedded in Nb thin\n  films: The origin of ferromagnetism in nanoparticles of nonmagnetic oxides is an\ninteresting area of research. In the present work, transport properties of\nniobium thin films, with beta-Ga2O3 nanoparticles embedded within them, are\npresented. Nanoparticles of beta-Ga2O3 embedded in a Nb matrix were prepared at\nroom temperature by radio frequency co-sputtering technique on Si (100) and\nglass substrates held at room temperature. The thin films deposited on Si\nsubstrates were subjected to Ar annealing at a temperature range of 600-650 C\nfor 1 hour. Films were characterized by X-ray diffraction (XRD), Micro-Raman\nand elemental identification was performed with an Energy Dispersive X-ray\nSpectroscopy (EDS). Transport measurements were performed down to liquid helium\ntemperatures by four-probe contact technique, showed characteristics analogous\nto those observed in the context of a Kondo system. A comparison of the\nexperimental data with the theoretical formalism of Kondo and Hamann is\npresented. It is suggested that this behavior arises from the existence of\nmagnetic moments associated with the oxygen vacancy defects in the\nnanoparticles of the nonmagnetic oxide Ga2O3.",
        "positive": "Phase Stability, Structures and Properties of the (Bi2)m(Bi2Te3)n\n  Natural Superlattices: The phase stability of the (Bi2)m(Bi2Te3)n natural superlattices has been\ninvestigated through the low temperature solid state synthesis of a number of\nnew binary BixTe1-x compositions. Powder X-ray diffraction revealed that an\ninfinitely adaptive series forms for 0.44 < x < 0.70, while an unusual 2-phase\nregion with continuously changing compositions is observed for 0.41 < x < 0.43.\nFor x > 0.70, mixtures of elemental Bi and an almost constant composition\n(Bi2)m(Bi2Te3)n phase are observed. Rietveld analysis of synchrotron X-ray\npowder diffraction data collected on Bi2Te (m = 2, n = 1) revealed substantial\ninterchange of Bi and Te between the Bi2 and Bi2Te3 blocks, demonstrating that\nthe block compositions are variable. All investigated phase pure compositions\nare degenerate semiconductors with low residual resistivity ratios and moderate\npositive magnetoresistances (R/R0 = 1.05 in 9 T). The maximum Seebeck\ncoefficient is +80 muV K-1 for x = 0.63, leading to an estimated thermoelectric\nfigure of merit, zT = 0.2 at 250 K."
    },
    {
        "anchor": "Protein arrangement on modified diamond-like carbon surfaces - An ARXPS\n  study: Understanding the nature of the interface between a biomaterial implant and\nthe biological fluid is an essential step towards creating improved implant\nmaterials. This study examined a diamond-like carbon coating biomaterial, the\nsurface energy of which was modified by Ar+ ion sputtering and laser\ngraphitisation. The arrangement of proteins was analysed by angle resolved\nX-ray photoelectron spectroscopy, and the effects of the polar component of\nsurface energy on this arrangement were observed. It was seen that polar groups\n(such as CN, CO) are more attracted to the coating surface due to the stronger\npolar interactions. This results in a segregation of these groups to the\nDLC-protein interface; at increasing takeoff angle (further from to DLC-protein\ninterface) fewer of these polar groups are seen. Correspondingly, groups that\ninteract mainly by dispersive forces (CC, CH) were found to increase in\nintensity as takeoff angle increased, indicating they are segregated away from\nthe DLC-protein interface. The magnitude of the segregation was seen to\nincrease with increasing polar surface energy, this was attributed to an\nincreased net attraction between the solid surface and polar groups at higher\npolar surface energy.",
        "positive": "Giant magnetic anisotropy of Co, Ru, and Os adatoms on MgO (001) surface: Large magnetic anisotropy energy (MAE) is desirable and critical for\nnanoscale magnetic devices. Here, using ligand-field level diagrams and density\nfunctional calculations, we well explain the very recent discovery [I. G. Rau\net al., Science 344, 988 (2014)] that an individual Co adatom on a MgO (001)\nsurface has a large MAE of more than 60 meV. More importantly, we predict that\na giant MAE up to 110 meV could be realized for Ru adatoms on MgO (001), and\neven more for the Os adatoms (208 meV). This is a joint effect of the special\nligand field, orbital multiplet, and significant spin-orbit interaction, in the\nintermediate-spin state of the Ru or Os adatoms on top of the surface oxygens.\nThe giant MAE could provide a route to atomic scale memory."
    },
    {
        "anchor": "Raman spectroscopic features of the neutral vacancy in diamond from ab\n  initio quantum-mechanical calculations: Quantum-mechanical ab initio calculations are performed to elucidate the\nvibrational spectroscopic features of a common irradiation-induced defect in\ndiamond, i.e. the neutral vacancy. Raman spectra are computed analytically\nthrough a Coupled-Perturbed-Hartree-Fock/Kohn-Sham approach as a function of\nboth different defect spin states and defect concentration. The experimental\nRaman features of defective diamond located in the 400-1300 cm-1 spectral\nrange, i.e. below the first-order line of pristine diamond at 1332 cm-1 , are\nwell reproduced, thus corroborating the picture according to which, at low\ndamage densities, this spectral region is mostly affected by non-graphitic sp3\ndefects. No peaks above 1332 cm-1 are found, thus ruling out previous tentative\nassignments of different spectral features (at 1450 and 1490 cm-1) to the\nneutral vacancy. The perturbation introduced by the vacancy to the thermal\nnuclear motion of carbon atoms in the defective lattice is discussed in terms\nof atomic anisotropic displacement parameters (ADPs), computed from converged\nlattice dynamics calculations.",
        "positive": "Charge separation dynamics and opto-electronic properties of a\n  diaminoterephthalate- C 60 diad: A novel diad composed of a diaminoterephthalate scaffold, covalently linked\nto a Fullerene derivative, is explored as a nanosized charge separation unit\npowered by solar energy. Its opto-electronic properties are studied and the\ncharge separation rate is determined. Simulations of the coupled electronic and\nnuclear dynamics in the Ehrenfest approximation are carried out ona sub 100 fs\ntime scale after photoexcitation in order to gain insights about the mechanisms\ndriving the the charge separation. In particular, the role of vibronic coupling\nand of the detailed morphology are highlighted."
    },
    {
        "anchor": "Accelerating charging dynamics in sub-nanometer pores: Having smaller energy density than batteries, supercapacitors have\nexceptional power density and cyclability. Their energy density can be\nincreased using ionic liquids and electrodes with sub-nanometer pores, but this\ntends to reduce their power density and compromise the key advantage of\nsupercapacitors. To help address this issue through material optimization, here\nwe unravel the mechanisms of charging sub-nanometer pores with ionic liquids\nusing molecular simulations, navigated by a phenomenological model. We show\nthat charging of ionophilic pores is a diffusive process, often accompanied by\noverfilling followed by de-filling. In sharp contrast to conventional\nexpectations, charging is fast because ion diffusion during charging can be an\norder of magnitude faster than in bulk, and charging itself is accelerated by\nthe onset of collective modes. Further acceleration can be achieved using\nionophobic pores by eliminating overfilling/de-filling and thus leading to\ncharging behavior qualitatively different from that in conventional, ionophilic\npores.",
        "positive": "Anomalous transport due to Weyl fermions in the chiral antiferromagnets\n  Mn$_3$$X$, $X$ = Sn, Ge: The recent discoveries of strikingly large zero-field Hall and Nernst effects\nin antiferromagnets Mn$_3$$X$, ($X$ = Sn, Ge) have brought the study of\nmagnetic topological states to the forefront of condensed matter research and\ntechnological innovation. These effects are considered fingerprints of Weyl\nnodes residing near the Fermi energy, promoting Mn$_3$$X$, ($X$ = Sn, Ge) as a\nfascinating platform to explore the elusive magnetic Weyl fermions. In this\nreview, we provide recent updates on the insights drawn from experimental and\ntheoretical studies of Mn$_3$$X$, ($X$ = Sn, Ge) by combining previous reports\nwith our new, comprehensive set of transport measurements of high-quality\nMn$_3$Sn and Mn$_3$Ge single crystals. In particular, we report\nmagnetotransport signatures specific to chiral anomalies in Mn$_3$Ge and planar\nHall effect in Mn$_3$Sn, which have not yet been found in earlier studies. The\nresults summarized here indicate the essential role of magnetic Weyl fermions\nin producing the large transverse responses in the absence of magnetization."
    },
    {
        "anchor": "Substantial magneto-electric coupling near room temperature in Bi2Fe4O9: We report remarkable multiferroic effects in polycrystalline Bi2Fe4O9.\nHigh-resolution X-ray diffraction shows that this compound has orthorhombic\nstructure. Magnetic measurements confirm an antiferromagnetic transition around\n260 K. A pronounced inverse S-shape anomaly in the loss tangent of dielectric\nmeasurement is observed near the Neel temperature. This feature shifts with the\napplication of magnetic field. These anomalies are indicative of substantial\ncoupling between the electric and magnetic orders in this compound.",
        "positive": "Super-transport of Excitons in Atomically Thin Organic Semiconductors at\n  the 2D Quantum Limit: Long-range and fast transport of coherent excitons is important for\ndevelopment of high-speed excitonic circuits and quantum computing\napplications. However, most of these coherent excitons have only been observed\nin some low-dimensional semiconductors when coupled with cavities, as there are\nlarge inhomogeneous broadening and dephasing effects on the exciton transport\nin their native states of the materials. Here, by confining coherent excitons\nat the 2D quantum limit, we firstly observed molecular aggregation enabled\nsuper-transport of excitons in atomically thin two-dimensional (2D) organic\nsemiconductors between coherent states, with a measured a high effective\nexciton diffusion coefficient of 346.9 cm2/sec at room temperature. This value\nis one to several orders of magnitude higher than the reported values from\nother organic molecular aggregates and low-dimensional inorganic materials.\nWithout coupling to any optical cavities, the monolayer pentacene sample, a\nvery clean 2D quantum system (1.2 nm thick) with high crystallinity (J type\naggregation) and minimal interfacial states, showed superradiant emissions from\nthe Frenkel excitons, which was experimentally confirmed by the\ntemperature-dependent photoluminescence (PL) emission, highly enhanced\nradiative decay rate, significantly narrowed PL peak width and strongly\ndirectional in-plane emission. The coherence in monolayer pentacene samples was\nobserved to be delocalized over 135 molecules, which is significantly larger\nthan the values (a few molecules) observed from other organic thin films. In\naddition, the super-transport of excitons in monolayer pentacene samples showed\nhighly anisotropic behaviour. Our results pave the way for the development of\nfuture high-speed excitonic circuits, fast OLEDs, and other opto-electronic\ndevices."
    },
    {
        "anchor": "Chiral charge-density wave in TiSe$_2$ due to photo-induced structural\n  distortions: A variety of experiments have been carried out to establish the origin of the\nchiral charge-density wave transition in 1T-TiSe$_2$, which in turn has led to\ncontradictory conclusions on the origin of this transition. Some studies\nsuggest the transition is a phonon-driven structural distortion while other\nstudies suggest it is an excitonic insulator phase transition that is\naccompanied by a lattice distortion. First, we propose these interpretations\ncan be reconciled if one analyzes the available experimental and theoretical\ndata within a formal definition of what constitutes an excitonic insulator as\ninitially proposed by Keldysh and Kopaev. Next, we present pump-probe\nmeasurements of circularly polarized optical transitions and first-principles\ncalculations where we highlight the importance of accounting for structural\ndistortions to explain the finite chirality of optical transitions in the CDW\nphase. We show that at the elevated electronic temperature that occurs upon\nphotoexcitation, there is a non-centrosymmetric structure that is\nnear-degenerate in energy with the centrosymmetric charge density wave\nstructure, which explains the finite chirality of the optical transitions\nobserved in the CDW phase of TiSe$_2$.",
        "positive": "Phonon Calculations in Cubic and Tetragonal Phases of SrTiO3: a\n  Comparative LCAO and Plane Wave Study: The atomic, electronic structure and phonon frequencies have been calculated\nin a cubic and low-temperature tetragonal SrTiO3 phases at the ab initio level.\nWe demonstrate that the use of hybrid exchange-correlation PBE0 functional\ngives the best agreement with experimental data. The results for the standard\nPBE and hybrid PBE0 are compared for the two types of basis sets: a linear\ncombination of atomic orbitals (LCAO, CRYSTAL09 computer code) and plane waves\n(PW, VASP 5.2 code). Relation between cubic and tetragonal antiferrodistortive\n(AFD) phases and the relevant AFD phase transition observed at 110 K is\ndiscussed in terms of group theory and illustrated with analysis of calculated\nsoft mode frequences at the {\\Gamma} and R points in the Brillouin zone. Based\non phonon calculations, the temperature dependences of the Helmholtz free\nenergy and heat capacity are in a good agreement with experiment."
    },
    {
        "anchor": "A first-principles DFT+GW study of spin-filter and spin-gapless\n  semiconducting Heusler compounds: Among Heusler compounds, the ones being magnetic semiconductors (also known\nas spin-filter materials) are widely studied as they offer novel\nfunctionalities in spintronic/magnetoelectronic devices. The spin-gapless\nsemiconductors are a special case. They possess a zero or almost-zero energy\ngap in one of the two spin channels. We employ the $GW$ approximation, which\nallows an elaborate treatment of the electronic correlations, to simulate the\nelectronic band structure of these materials. Our results suggest that in most\ncases the use of $GW$ self energy instead of the usual density functionals is\nimportant to accurately determine the electronic properties of magnetic\nsemiconductors.",
        "positive": "Pentamode metamaterials with independently tailored bulk modulus and\n  mass density: We propose a class of linear elastic three-dimensional metamaterials for\nwhich the effective parameters bulk modulus and mass density can be adjusted\nindependently over a large range|which is not possible for ordinary materials.\nFirst, we systematically evaluate the static mechanical properties and the\nphonon dispersion relations. We show that the two are quantitatively consistent\nin the long-wavelength limit. To demonstrate the feasibility, corresponding\nfabricated polymer microstructures are presented. Finally, we discuss\ncalculations for laminates composed of alternating layers of two different\nmetamaterials with equal bulk modulus yet different mass density. This leads to\nmetamaterials with effectively anisotropic uniaxial dynamic mass density\ntensors."
    },
    {
        "anchor": "Applications for ultimate spatial resolution in LASER based $\u03bc$-ARPES:\n  A FeSe case study: Combining Angle resolved photoelectron spectroscopy (ARPES) and a\n$\\mu$-focused Laser, we have performed scanning ARPES microscopy measurements\nof the domain population within the nematic phase of FeSe single crystals. We\nare able to demonstrate a variation of the domain population density on a scale\nof a few 10 $\\mu$m while constraining the upper limit of the single domain size\nto less than 5 $\\mu m$. This experiment serves as a demonstration of how\ncombining the advantages of high resolution Laser ARPES and an ultimate control\nover the spatial dimension can improve investigations of materials by reducing\nthe cross contamination of spectral features of different domains.",
        "positive": "Emergence of Winner-takes-all Connectivity Paths in Random Nanowire\n  Networks: Nanowire networks are promising memristive architectures for neuromorphic\napplications due to their connectivity and neurosynaptic-like behaviours. Here,\nwe demonstrate a self-similar scaling of the conductance of networks and the\njunctions that comprise them. We show this behavior is an emergent property of\nany junction-dominated network. A particular class of junctions naturally leads\nto the emergence of conductance plateaus and a \"winner-takes-all\" conducting\npath that spans the entire network, and which we show corresponds to the\nlowest-energy connectivity path. These results point to the possibility of\nindependently addressing memory or conductance states in complex systems and is\nexpected to have important implications for neuromorphic devices based on\nreservoir computing."
    },
    {
        "anchor": "Ferromagnetic and Antiferromagnetic Coupling of Spin Molecular\n  Interfaces with High Thermal Stability: We report an advanced organic spin-interface architecture with magnetic\nremanence at room temperature, constituted by metal phthalocyanine molecules\nmagnetically coupled with Co layer(s), mediated by graphene. Fe- and\nCu-phthalocyanines assembled on graphene/Co have identical structural\nconfigurations, but FePc couples antiferromagnetically with Co up to room\ntemperature, while CuPc couples ferromagnetically with weaker coupling and\nthermal stability, as deduced by element-selective X-ray magnetic circular\ndichroic signals. The robust antiferromagnetic coupling is stabilized by a\nsuperexchange interaction, driven by the out-of-plane molecular orbitals\nresponsible of the magnetic ground state and electronically decoupled from the\nunderlying metal via the graphene layer, as confirmed by ab initio theoretical\npredictions. These archetypal spin interfaces can be prototypes to demonstrate\nhow antiferromagnetic and/or ferromagnetic coupling can be optimized by\nselecting the molecular orbital symmetry.",
        "positive": "Nucleation in Systems with Elastic Forces: Systems with long-range interactions when quenced into a metastable state\nnear the pseudo-spinodal exhibit nucleation processes that are quite different\nfrom the classical nucleation seen near the coexistence curve. In systems with\nlong-range elastic forces the description of the nucleation process can be\nquite subtle due to the presence of bulk/interface elastic compatibility\nconstraints. We analyze the nucleation process in a simple 2d model with\nelastic forces and show that the nucleation process generates critical droplets\nwith a different structure than the stable phase. This has implications for\nnucleation in many crystal-crystal transitions and the structure of the final\nstate."
    },
    {
        "anchor": "Conductivity behavior of La$_{0.75}$Ca$_{0.25}$MnO$_{3}$ in vicinity of\n  ferromagnetic-paramagnetic transition studied with single current pulses: Temperature and current dependences of resistivity of bulk\nLa$_{0.75}$Ca$_{0.25}$MnO$_{3}$ sample grown by the floating-zone method were\nstudied using single ramp pulses of current. It is found that near the Curie\ntemperature $T_C$ the sample resistance depends substantially on current\nmagnitude. The observed features can be determined by inhomogeneous Joule\noverheating due to mixed phase state of manganites near the\nferromagnetic-paramagnetic transition and percolation character of this\ntransition.",
        "positive": "On the Onset of the Flash Transition in Single Crystals of Cubic\n  Zirconia: The reported onset temperatures of the flash transition in cubic zirconia\nsingle crystals have been analyzed in the present note. The analysis for\nhigh-temperature low-field data gives an activation energy of 0.99 eV for the\ncharge transport, which agrees well with the measured ionic conductivity data\nin cubic zirconia single crystal. Electrical reduction is believed to play an\nadditional role under low-temperature high-field conditions, facilitating\nelectrical/thermal runaway under more modest conditions."
    },
    {
        "anchor": "Study of the elastocaloric effect and mechanical behavior for the NiTi\n  shape memory alloys: The NiTi shape memory alloy exhibited excellent superelastic property and\nelastocaloric effect. Large temperature changes of 30 K upon loading and -19 K\nupon unloading were obtained at room temperature, which were higher than those\nof the other NiTi-based materials and among the highest values reported in the\nelastocaloric materials. The asymmetry of the measured temperature changes\nbetween loading and unloading process was ascribed to the friction dissipation.\nThe large temperature changes originated from the large entropy change during\nthe stress-induced martensite transformation (MT) and the reverse MT. A large\ncoefficient-of-performance of the material (COPmater) of 11.7 was obtained,\nwhich decreased with increasing the applied strain. These results are very\nattractive in the present solid-state cooling which is potential to replace the\nvapor compression refrigeration technologies.",
        "positive": "Analysis of exchange interactions in dimers of Mn3 single-molecule\n  magnets, and their sensitivity to external pressure: In light of the potential use of single-molecule magnets (SMMs) in emerging\nquantum information science initiatives, we report first-principles\ncalculations of the magnetic exchange interactions in [$\\mathrm{Mn}_{3}$]$_{2}$\ndimers of $\\mathrm{Mn}_3$ SMMs, connected by covalently-attached organic\nlinkers, that have been synthesized and studied experimentally by\nmagnetochemistry and EPR spectroscopy. Energy evaluations calibrated to\nexperimental results give the sign and order of magnitude of the exchange\ncoupling constant ($J_{12}$) between the two $\\mathrm{Mn}_{3}$ units that match\nwith fits of magnetic susceptibility data and EPR spectra. Downfolding into the\n$\\mathrm{Mn}$ $d$-orbital basis, Wannier function analysis has shown that\nmagnetic interactions can be channeled by ligand groups that are bonded by van\nder Waals interaction and/or by the linkers via covalent bonding of specific\nsystems, and effective tight-binding Hamiltonians are obtained. We call this\nlong-range coupling that involves a group of atoms a collective exchange.\nOrbital projected spin density of states and alternative Wannier\ntransformations support this observation. To assess the sensitivity of $J_{12}$\nto external pressure, stress-strain curves have been investigated for both\nhydrostatic and uniaxial pressure, which have revealed a switch of $J_{12}$\nfrom ferromagnetic to antiferromagnetic with increasing pressure."
    },
    {
        "anchor": "Magnetic interactions in intercalated transition metal dichalcogenides:\n  a study based on ab initio model construction: Transition metal dichalcogenides (TMDs) are known to have a wide variety of\nmagnetic structures by hosting other transition metal atoms in the van der\nWaals gaps. To understand the chemical trend of the magnetic properties of the\nintercalated TMDs, we perform a systematic first-principles study for 48\ncompounds with different hosts, guests, and composition ratios. Starting with\ncalculations based on spin density functional theory, we derive classical spin\nmodels by applying the Liechtenstein method to the ab initio Wannier-based\ntight-binding model. We show that the calculated exchange couplings are overall\nconsistent with the experiments. In particular, when the composition rate is\n1/3, the chemical trend can be understood in terms of the occupation of the\n3d-orbital in the intercalated transition metal. The present results give us a\nuseful guiding principle to predict the magnetic structure of compounds that\nare yet to be synthesized.",
        "positive": "Quantum Dynamics in Nanoscale Magnets in Dissipative Environments: In discrete energy structure of nanoscale magnets, nonadiabatic transitions\nat avoided level crossings lead to fundamental processes of dynamics of\nmagnetizations. The thermal environment causes dissipative effects on these\nprocesses. In this paper we review the features of the nonadiabatic transition\nand the influence of the thermal environment. In particular we discuss the\ntemperature independent stepwise structure of magnetization at very low\ntemperatures (deceptive nonadiabatic transition), the alternate enhancement of\nrelaxation in the sequence of resonant tunneling points (parity effects), and\nprocesses caused by combinations of nonadiabatic transitions and disturbance\ndue to external noises."
    },
    {
        "anchor": "Mechanism to Generate a Two-Dimensional Electron Gas at the Surface of\n  the Charge-Ordered Semiconductor BaBiO3: In this work, we find by means of first principle calculations a new physical\nmechanism to generate a two dimensional electron gas, namely, the breaking of\ncharge ordering at the surface of a charge ordered semiconductor due to the\nincomplete oxygen environment of the surface ions. The emergence of the 2D gas\nis independent of the presence of oxygen vacancies or polar discontinuities;\nthis is a self-doping effect. This mechanism might apply to many charge ordered\nsystems, in particular, we study the case of BaBiO3(001). In bulk, this\nmaterial is a prototype of a \"forbidden valence\" compound in which the formal\n\"metallic\" Bi4+ state is skipped exhibiting a charge disproportionated Bi3+ -\nBi5+ ordered structure. At room temperature, this charge disproportionation\ntogether with the breathing distortions gives rise to a Peierls semiconductor\nwith monoclinic crystal structure. At higher temperature (T > 750 K) or upon\ndoping, it turns cubic and metallic. Interestingly, doped BaBiO3 was one of the\nfirst non-cuprate high-Tc superconductors discovered. The outer layer of the\nBi-terminated simulated surface turns more cubic- like and metallic while the\ninner layers remain in the insulating monoclinic state. On the other hand, the\nmetallization does not occur for the Ba termination, a fact that makes this\nsystem appealing for nanostructuring. Finally, this finding sets another\npossible route for future exploration: the potential scenario of 2D\nsuperconductivity at the BaBiO3 surface.",
        "positive": "Fabrication and Characterization of Modulation-Doped ZnSe/(Zn,Cd)Se\n  (110) Quantum Wells: A New System for Spin Coherence Studies: We describe the growth of modulation-doped ZnSe/(Zn,Cd)Se quantum wells on\n(110) GaAs substrates. Unlike the well-known protocol for the epitaxy of\nZnSe-based quantum structures on (001) GaAs, we find that the fabrication of\nquantum well structures on (110) GaAs requires significantly different growth\nconditions and sample architecture. We use magnetotransport measurements to\nconfirm the formation of a two-dimensional electron gas in these samples, and\nthen measure transverse electron spin relaxation times using time-resolved\nFaraday rotation. In contrast to expectations based upon known spin relaxation\nmechanisms, we find surprisingly little difference between the spin lifetimes\nin these (110)-oriented samples in comparison with (100)-oriented control\nsamples."
    },
    {
        "anchor": "Grain Size and Lattice Parameter's Influence on Band Gap of SnS Thin\n  Nano-crystalline Films: The parameters influencing the band gap of tin sulphide thin nano-crystalline\nfilms have been investigated. Both grain size and lattice parameters are known\nto influence the band gap. The present study initially investigates each\ncontribution individually. The experimentally determined dependency on lattice\nparameter is verified by theoretical calculations. We also suggest how to treat\nthe variation of band gap as a two variable problem. The results allow us to\nshow dependency of effective mass (reduced) on lattice unit volume.",
        "positive": "SiGe Raman spectra vs. local clustering/anticlustering : Percolation\n  scheme and ab initio calculations: We formalize within the percolation scheme, that operates along the linear\nchain approximation, namely at one dimension (1D), an intrinsic ability behind\nRaman scattering to achieve a quantitative insight into local clustering or\nanticlustering in an alloy, using SiGe as a case study. For doing so, we derive\ngeneral expressions of the individual fractions of the six SiGe\npercolation-type oscillators [1(Ge-Ge), 3(Si-Ge), 2(Si-Si)], which monitor\ndirectly the Raman intensities, via a relevant order parameter k. This is\nintroduced by adapting to the 1D oscillators of the SiGe diamond version of the\n1D percolation scheme, namely along a fully consistent 1D treatment, the\napproach originally used by Verleur and Barker for the three-dimensional (3D)\noscillators of their 1D cluster scheme applying to zincblende alloys [H.W.\nVerleur and A.S. Barker, Phys. Rev. 149, 715 (1966)], a somehow problematic one\nin fact, due to its 3D vs. 1D ambivalence. Predictive k-dependent intensity\ninterplays between the SiGe (50 at.%Si) Raman lines are confronted with\nexisting experimental data and with ab initio Raman spectra obtained by using\nlarge (32 atom) disordered supercells matching the required k values, with\nspecial attention to the Si-Ge triplet and to the Si-Si doublet, respectively."
    },
    {
        "anchor": "Explaining the x-ray nonlinear susceptibility of diamond and silicon\n  near absorption edges: We report the observation and the theoretical explanation of the parametric\ndown-conversion nonlinear susceptibility at the $K$-absorption edge of diamond\nand at the $L_{23}$-absorption edge of a silicon crystal. Using arguments\nsimilar to those invoked to successfully predict resonant inelastic x-ray\nspectra, we derive an expression for the renormalization term of the non-linear\nsusceptibility at the x-ray edges, which can be evaluated by using\nfirst-principles calculations of the atomic scattering factor $f_1$. Our model\nis shown to reproduce the observed enhancement of the parametric\ndown-conversion at the diamond $K$ and the Si $L_{23}$ edges rather than the\nsuppression previously claimed.",
        "positive": "Room temperature ferromagnetism in intercalated Fe3-xGeTe2 van der Waals\n  magnet: Among several well-known transition metal-based compounds, the van der Waals\n(vdW) Fe3-xGeTe2 (FGT) magnet is a strong candidate for use in two-dimensional\n(2D) magnetic devices due to its strong perpendicular magnetic anisotropy,\nsizeable Curie temperature (TC ~ 154 K), and versatile magnetic character that\nis retained in the low-dimensional limit. While the TC remains far too low for\npractical applications, there has been a successful push toward improving it\nvia external driving forces such as pressure, irradiation, and doping. Here we\npresent experimental evidence of a novel room-temperature (RT) ferromagnetic\nphase induced by the electrochemical intercalation of common tetrabutylammonium\ncations (TBA+) into FGT bulk crystals. We obtained Curie temperatures as high\nas 350 K with chemical and physical stability of the intercalated compound. The\ntemperature-dependent Raman measurements in combination with vdW-corrected ab\ninitio calculations suggest that charge transfer (electron doping) upon\nintercalation could lead to the observation of RT ferromagnetism. This work\ndemonstrates that molecular intercalation is a viable route in realizing\nhigh-temperature vdW magnets in an inexpensive and reliable manner."
    },
    {
        "anchor": "Dynamic Peach-Koehler self-force, inertia, and radiation damping of a\n  regularized dislocation: The elastodynamic Peach-Koehler force is computed for a fully-regularized\nstraight dislocation with isotropic core in continuum isotropic elastic\nelasticity, in compact forms involving partial mass or impulsion functions\nrelative to shear and compressional waves. The force accounts for both dynamic\nradiation damping and inertia. The expressions are valid indifferently for\nsubsonic or supersonic velocities. Results are compared with the case of a\nflat-core dislocation of the Peierls-Eshelby type, for a motion of jump from\nrest to constant velocity. In the steady-state limit, the Lagrangian function\nrelevant to expressing the force in the flat-core case must be replaced by a\nrelated but different function for the regularized dislocation. However, by\nsuitably defining the regularizing dislocation width, the steady-state limits\nof the force for the fully-regularized and flat-core dislocations can be\nmatched exactly.",
        "positive": "A unified Green's function approach for spectral and thermodynamic\n  properties from algorithmic inversion of dynamical potentials: Dynamical potentials appear in many advanced electronic-structure methods,\nincluding self-energies from many-body perturbation theory, dynamical\nmean-field theory, electronic-transport formulations, and many embedding\napproaches. Here, we propose a novel treatment for the frequency dependence,\nintroducing an algorithmic inversion method that can be applied to dynamical\npotentials expanded as sum over poles. This approach allows for an exact\nsolution of Dyson-like equations at all frequencies via a mapping to a matrix\ndiagonalization, and provides simultaneously frequency-dependent (spectral) and\nfrequency-integrated (thermodynamic) properties of the Dyson-inverted\npropagators. The transformation to a sum over poles is performed introducing\n$n$-th order generalized Lorentzians as an improved basis set to represent the\nspectral function of a propagator, and using analytic expressions to recover\nthe sum-over-poles form. Numerical results for the homogeneous electron gas at\nthe $G_0W_0$ level are provided to argue for the accuracy and efficiency of\nsuch unified approach."
    },
    {
        "anchor": "Strong light-matter coupling in MoS$_2$: Polariton-based devices require materials where light-matter coupling under\nambient conditions exceeds losses, but our current selection of such materials\nis limited. Here we measured the dispersion of polaritons formed by the $A$ and\n$B$ excitons in thin MoS$_2$ slabs by imaging their optical near fields. We\ncombined fully tunable laser excitation in the visible with a scattering\nnear-field optical microscope to excite polaritons and image their optical near\nfields. We obtained the properties of bulk MoS$_2$ from fits to the slab\ndispersion. The in-plane excitons are in the strong regime of light-matter\ncoupling with a coupling strength ($40-100\\,$meV) that exceeds their losses by\nat least a factor of two. The coupling becomes comparable to the exciton\nbinding energy, which is known as very strong coupling. MoS$_2$ and other\ntransition metal dichalcogenides are excellent materials for future polariton\ndevices.",
        "positive": "Low temperature physical properties of Co-35Ni-20Mo-10Cr alloy MP35N: Multiphase Co-35Ni-20Mo-10Cr alloy MP35N is a high strength alloy with\nexcellent corrosion resistance. Its applications span chemical, medical, and\nfood processing industries. Thanks to its high modulus and high strength, it\nfound applications in reinforcement of ultra-high field pulsed magnets.\nRecently, it has also been considered for reinforcement in superconducting\nwires used in ultra-high field superconducting magnets. For these applications,\naccurate measurement of its physical properties at cryogenic temperatures is\nvery important. In this paper, physical properties including electrical\nresistivity, specific heat, thermal conductivity, and magnetization of\nas-received and aged samples are measured from 2 to 300 K. The electrical\nresistivity of the aged sample is slightly higher than the as-received sample,\nboth showing a weak linear temperature dependence in the entire range of 2 -\n300 K. The measured specific heat Cp of 0.43 J/g-K at 295 K agrees with a\ntheoretical prediction, but is significantly smaller than the values in the\nliterature. The thermal conductivity between 2 and 300 K is in good agreement\nwith the literature which is only available above 77 K. Magnetic property of\nMP35N changes significantly with aging. The as-received sample exhibits Curie\nparamagnetism with a Curie constant C = 0.175 K. While the aged sample contains\nsmall amounts of a ferromagnetic phase even at room temperature. The measured\nMP35N properties will be useful for the engineering design of pulsed magnets\nand superconducting magnets using MP35N as reinforcement."
    },
    {
        "anchor": "Strongly coupled phase transition in ferroelectric/correlated electron\n  oxide heterostructures: We fabricated ultrathin ferroelectric/correlated electron oxide\nheterostructures composed of the ferroelectric Pb(Zr0.2Ti0.8)O3 and the\ncorrelated electron oxide (CEO) La0.8Sr0.2MnO3 on SrTiO3 substrates by pulsed\nlaser epitaxy. The hole accumulation in the ultrathin CEO layer was\nsubstantially modified by heterostructuring with the ferroelectric layer,\nresulting in an insulator-metal transition. In particular, our thickness\ndependent study showed that drastic changes in transport and magnetic\nproperties were strongly coupled to the modulation of charge carriers by\nferroelectric field effect, which was confined to the vicinity of the\ninterface. Thus, our results provide crucial evidence that strong ferroelectric\nfield effect control can be achieved in ultrathin (10 nm) heterostructures,\nyielding at least a 100,000-fold change in resistivity.",
        "positive": "Electronic and magnetic properties of the Jahn-Teller active fluoride\n  $\\mathrm{NaCrF_{3}}$ from first-principles calculations: In perovskite-type compounds, the interplay of cooperative Jahn-Teller\neffect, electronic correlations and orbital degree of freedom leads to\nintriguing properties. $\\mathrm{NaCrF_{3}}$ is a newly synthesized Jahn-Teller\nactive fluoroperovskite where the $\\mathrm{CrF_{6}^{4-}}$ octahedrons are\nconsiderably distorted. Based on the first-principles calculation, we analyze\nits electronic structure and magnetic properties. Our numerical results show\nthat the $\\mathrm{Cr^{2+}}$ ions adopt the high-spin\n$t_{2g\\uparrow}^{3}e_{g\\uparrow}^{1}$ configuration with $G$-type orbital\nordering. We also estimate the magnetic exchange couplings and find that the\nin-plane and interplanar nearest-neighbor interactions are ferromagnetic and\nantiferromagnetic, respectively. The ground state of this material is $A$-type\nantiferromagnetic, in agreement with the experiments. Reasonable Curie-Weiss\nand $\\mathrm{N\\acute{e}el}$ temperatures compared to the experiments are given\nby mean-field approximation theory. Our results give a complete explanation of\nits electronic structure, magnetic and orbital order, and help to further\ncomprehend the behaviors of Jahn-Teller active perovskite-type fluoride."
    },
    {
        "anchor": "Spin-state ordering and magnetic structures in YBaCo2O5.5/5.44: The antiferromagnetic - ferromagnetic phase transition in YBaCo2O5.50 and\nYBaCo2O5.44 cobaltites with different types of oxygen-ion ordering in the\n[YO0.5/0.44] layers has been studied by neutron powder diffraction. Using the\nmagnetic symmetry arguments in combination with group-theoretical analysis, the\ncrystal and magnetic structures above and below the phase transformation\ntemperature, Ti, were determined and successfully refined. In both cases, the\nproposed models involve a spin-state ordering between diamagnetic (t2g6eg0, S =\n0) and paramagnetic (t2g4eg2, S = 2) Co3+ ions with octahedral coordination.\nElectronic ordering results in a nonzero spontaneous magnetic moment in the\nhigh-temperature magnetic phases with isotropic negative exchange interactions.\nIn the case of YBaCo2O5.5, the phase transformation does not change Pmma\nsymmetry of the crystal structure. The wave vectors of magnetic structures\nabove and below Ti are k = 0 and k = c*/2, respectively. In the case of\nYBaCo2O5.44, a crossover P4/nmm - I4/mmm was involved to solve the\nlow-temperature magnetic structure. The wave vectors in both high-temperature\nand low-temperature magnetic phases are k = 0. Mechanisms of the phase\ntransformation in both compositions are discussed in the light of obtained\nmagnetic structures. The proposed spin configurations were compared with other\nmodels reported in literature.",
        "positive": "Electric field induced irreversible transformation to the R3c phase and\n  its influence on the giant piezo-strain behaviour of lead-free system-\n  Na0.5Bi0.5TiO3-BaTiO3-K0.5Na0.5NbO3: A systematic study of the structural, dielectric and piezoelectric behavior\nof NBT-BT-KNN."
    },
    {
        "anchor": "In-situ observation of the formation of laser-induced periodic surface\n  structures with extreme spatial and temporal resolution: Irradiation of solid surfaces with intense ultrashort laser pulses represents\na unique way of depositing energy into materials. It allows to realize states\nof extreme electronic excitation and/or very high temperature and pressure, and\nto drive materials close to and beyond fundamental stability limits. As a\nconsequence, structural changes and phase transitions often occur along unusual\npathways and under strongly non-equilibrium conditions. Due to the inherent\nmultiscale nature - both temporally and spatially - of these irreversible\nprocesses their direct experimental observation requires techniques that\ncombine high temporal resolution with the appropriate spatial resolution and\nthe capability to obtain good quality data on a single pulse/event basis. In\nthis respect fourth generation light sources, namely short wavelength, short\npulse free electron lasers (FELs) are offering new and fascinating\npossibilities. As an example, this chapter will discuss the results of\nscattering experiments carried at the FLASH free electron laser at DESY\n(Hamburg, Germany), which allowed us to resolve laser-induced structure\nformation at surfaces on the nanometer to sub-micron length scale and in\ntemporal regimes ranging from picoseconds to several nanoseconds with\nsub-picosecond resolution.",
        "positive": "Fingerprint of fractional charge transfer at metal/organic interface: Although physisorption is a widely occurring mechanism of bonding at the\norganic/metal interface, contradictory interpretations of this phenomenon are\noften reported. Photoemission and X-ray absorption spectroscopy investigations\nof nanorods of a substituted pentacene, 2,3,9,10-tetrafluoropentacene,\ndeposited on gold single crystals reveal to be fundamental to identify the\nbonding mechanisms. We find fingerprints of a fractional charge transfer from\nthe clean metal substrate to the physisorbed molecules. This phenomenon is\nunambiguously recognizable by a non-rigid shift of the core-level main lines\nwhile the occupied states at the interface stay mostly unperturbed, and the\nunoccupied states experience pronounced changes. The experimental results are\ncorroborated by first-principles calculations."
    },
    {
        "anchor": "Using coherent X-rays to directly measure the propagation velocity of\n  defects during thin film deposition: The properties of artificially grown thin films are often strongly affected\nby the dynamic relationship between surface growth processes and subsurface\nstructure. Coherent mixing of X-ray signals promises to provide an approach to\nbetter understand such processes. Here, we demonstrate the continuously\nvariable mixing of surface and bulk scattering signals during real-time studies\nof sputter deposition of a-Si and a-WiS2 films by controlling the X-ray\npenetration and escape depths in coherent grazing incidence small angle X-ray\nscattering (Co-GISAXS). Under conditions where the X-ray signal comes from both\nthe growth surface and the thin film bulk, oscillations in temporal\ncorrelations arise from coherent interference between scattering from\nstationary bulk features and from the advancing surface. We also observe\nevidence that elongated bulk features propagate upward at the same velocity as\nthe surface. Additionally, a highly surface sensitive mode is demonstrated that\ncan access the surface dynamics independently of the subsurface structure.",
        "positive": "Modelling of Spintronic Terahertz Emitters as a function of spin\n  generation and diffusion geometry: Spintronic THz emitters (STE) are efficient THz sources constructed using\nthin heavy-metal (HM) and ferromagnetic-metal (FM) layers. To improve the\nperformance of the STE, different structuring methods (trilayers, stacked\nbilayers) have been experimentally applied. A theoretical description of the\noverall THz emission process is necessary to optimize the efficiency of STE. In\nparticular, geometry, composition, pump laser frequency, and spin diffusion\nwill be significant in understanding the pathways for further research\ndevelopments. This work will apply a generalized model based on a modified\nTransfer Matrix Method (TMM). We will consider the spin generation and\ndiffusion in the FM and HM layers and explain the spintronic THz emission\nprocess. This model is suitable for calculating emitted THz signal as a\nfunction of FM and HM thicknesses for different geometrical configurations. We\nwill investigate a bilayer geometry as a test case, but the extension to a\nmulti-layer configuration is straightforward. We will show how the different\nconfigurations of the sample will influence the THz emission amplitude."
    },
    {
        "anchor": "First-Principles Calculations of the Near-Edge Optical Properties of\n  \\b{eta}-Ga2O3: We use first-principles calculations based on many-body perturbation theory\nto investigate the near-edge electronic and optical properties of\n\\b{eta}-Ga2O3. The fundamental band gap is indirect, but the minimum direct gap\nis only 29 meV higher in energy, which explains the strong near-edge\nabsorption. Our calculations verify the anisotropy of the absorption onset and\nexplain the range (4.4-5.0 eV) of experimentally reported band-gap values. Our\nresults for the radiative recombination rate indicate that intrinsic light\nemission in the deep-UV range is possible in this indirect-gap semiconductor at\nhigh excitation. Our work demonstrates the applicability of \\b{eta}-Ga2O3 for\ndeep-UV detection and emission.",
        "positive": "Determination of Al occupancy and local structure for\n  \\b{eta}-(AlxGa1-x)2O3 alloys across nearly full composition range from\n  Rietveld analysis: Al occupancy and local structure (bond length and bond angles) for monoclinic\n\\b{eta}-(AlxGa1-x)2O3 alloys, with Al compositions (x) up to 90%, have been\ndetermined from Rietveld refinement of x-ray diffraction data. Al atom\npreferentially occupies octahedron (Oh) atomic site in comparison to\ntetrahedron (Td) atomic site. However, sizable number of Td atomic sites i.e.\n20% for Al composition of 5% remain occupied by Al atoms, which is found to\nincrease sharply with Al composition. The Oh atomic sites are not fully\noccupied by Al atoms even for Al composition of 90%. The lattice parameters\n(band gap) of \\b{eta}-(AlxGa1-x)2O3 alloy decrease (increases) linearly with Al\ncomposition, but a change in slope of variation of both lattice parameters and\nband gap is observed at around Al composition of 50%. The lattice is found to\nbe distorted for Al compositions more than 50% as indicated by large change in\nthe bond angles. The lattice distortion is determined to be the origin for the\nobserved change in slope for the variation of both lattice parameters and band\ngap for monoclinic \\b{eta}-(AlxGa1-x)2O3 alloy system. Our results provide an\ninsight in to the local structure of \\b{eta}-(AlxGa1-x)2O3 alloys, which are\nrequired to have better understanding of their physical properties."
    },
    {
        "anchor": "Phase Diagram of Carbon Nickel Tungsten: Superatom Model: Carbon solubility in face-centered cubic Ni-W alloys and the phase diagram of\nC-Ni-W are investigated by means of first principle calculations and semi-grand\ncanonical Monte Carlo simulations. With density functional theory (DFT) total\nenergies as fitting data, we build a superatom model for efficient simulation.\nMulti-histogram analysis is utilized to predict free energies for different\ncompositions and temperatures. By comparing free energies of competing phases,\nwe are able to predict carbon solubility and phase diagrams of C-Ni-W at\ndifferent temperatures. A simple ideal mixing approximation gives qualitatively\nsimilar predictions.",
        "positive": "Ni3TeO6 - a collinear antiferromagnet with ferromagnetic honeycomb\n  planes: We report a comprehensive study of magnetic properties of Ni3TeO6. The system\ncrystallizes in a noncentrosymmetric rhombohedral lattice, space group R3.\nThere are three differently coordinated Ni atoms in the unit cell. Two of them\nform an almost planar honeycomb lattice, while the third one is placed between\nthe layers. Magnetization and specific heat measurements revealed a single\nmagnetic ordering at TN = 52 K. Below TN the susceptibility with the magnetic\nfield parallel to the c-axis drops towards zero while the perpendicular\nsusceptibility remains constant, a characteristic of antiferromagnetic\nmaterials. Neutron diffraction confirmed that the system is antiferromagnet\nbelow TN with ferromagnetic ab-planes stacked antiferromagnetically along the\nc-axis. All Ni moments are in the S = 1 spin state and point along the c-axis."
    },
    {
        "anchor": "BaHgSn: A Dirac semimetal with surface hourglass fermions: We proposed that BaHgSn is a Dirac semimetal (DSM) which can host\nhourglass-like surface states (HSSs) as protected by nonsymmorphic glide\nsymmetry. Compared to KHgSb, an isostructural topological crystalline insulator\nwith the same HSSs, BaHgSn has an additional band inversion at $\\Gamma$ point.\nThis band inversion is induced by the stronger interlayer coupling among Hg-Sn\nhoneycomb layers than that among Hg-Sb-layers in KHgSb, which leads to bulk\nDirac nodes in BaHgSn along the layer stacking direction $\\Gamma$-$A$. In\naddition, the mirror Chern number $C_{i}$ protected by the mirror plane\n$\\overline{M}_{z}$ ($k_z$=0) changes from 2 in KHgSb to 3 in BaHgSn. Therefore,\nwhen a compressive uniaxial strain is applied along the $y$ axis to break the\nrotation symmetry protecting the DSM state, BaHgSn becomes a strong topological\ninsulator with $Z_{2}$ indices of $(1;000)$ and the topological surface Dirac\ncone co-exists with HSSs on the (010) surface. The Wilson-loop spectra have\nbeen calculated to verify these topological features. The calculated surface\nstates, the Fermi surfaces and their quasiparticle interference patterns are\nready to be compared with experimental measurements.",
        "positive": "Machine Learning for Predicting Thermal Transport Properties of Solids: Quantitative descriptions of the structure-thermal property correlation have\nbeen a bottleneck in designing materials with superb thermal properties. In the\npast decade, the first-principles phonon calculations using density functional\ntheory and the Boltzmann transport equation have become a common practice for\npredicting the thermal conductivity of new materials. However, first-principles\ncalculations are too costly for high-throughput material screening and\nmulti-scale structural design. First-principles calculations also face several\nfundamental challenges in modeling thermal transport properties, e.g., of\ncrystalline materials with defects, of amorphous materials, and for materials\nat high temperatures. In the past five years, machine learning started to play\na role in solving these challenges. This review provides a comprehensive\nsummary and discussion on the state-of-the-art, future opportunities, and the\nremaining challenges in implementing machine learning for studying thermal\nconductivity. After an introduction to the working principles of machine\nlearning and descriptors of material structures, recent research using machine\nlearning to study thermal transport is discussed. Three major applications of\nmachine learning for predicting thermal properties are discussed. First,\nmachine learning is applied to solve the challenges in modeling phonon\ntransport of crystals with defects, in amorphous materials, and at high\ntemperatures. Machine learning is used to build high-fidelity interatomic\npotentials to bridge the gap between first-principles calculations and\nmolecular dynamics simulations. Second, machine learning can be used to study\nthe correlation between thermal conductivity and other properties for\nhigh-throughput materials screening. Finally, machine learning is a powerful\ntool for structural design to achieve target thermal conductance or thermal\nconductivity."
    },
    {
        "anchor": "Thermal and Electrical Properties of gamma-NaxCoO2 (0.70 < x < 0.78): We have performed specific heat and electric resistivity measurements of\nNa$_{x}$CoO$_{2}$ ($x=0.70$-0.78). Two anomalies have been observed in the\nspecific heat data for $x=0.78$, corresponding to magnetic transitions at\n$T_{c}=22$ K and $T_{k}\\simeq 9$ K reported previously. In the electrical\nresistivity, a steep decrease at $T_{c}$ and a bending-like variation at\n$T_{b}$(=120K for $x=0.78$) have been observed. Moreover, we have investigated\nthe $x$-dependence of these parameters in detail. The physical properties of\nthis system are very sensitive to $x$, and the inconsistent results of previous\nreports can be explained by a small difference in $x$. Furthermore, for a\nhigher $x$ value, a phase separation into Na-rich and Na-poor domains occurs as\nwe previously proposed, while for a lower $x$ value, from characteristic\nbehaviors of the specific heat and the electrical resistivity at the\nlow-temperature region, the system is expected to be in the vicinity of the\nmagnetic instability which virtually exists below $x=0.70$.",
        "positive": "Diverse forms of $\u03c3$ bonding in two-dimensional Si allotropes:\n  Nematic orbitals in the $MoS_2$ structure: The interplay of $sp^2$- and $sp^3$-type bonding defines silicon allotropes\nin two- and three-dimensional forms. A novel two-dimensional phase bearing\nstructural resembleance to a single MoS$_2$ layer is found to possess a lower\ntotal energy than low-buckled silicene and to be stable in terms of its phonon\ndispersion relations. A new set of cigar-shaped, nematic orbitals originating\nfrom the Si $sp^2$ orbitals realizes bonding with a 6-fold coordination of the\ninner Si atoms of the layer. The identification of these nematic orbitals\nadvocates diverse Si bonding configurations different from those of C atoms."
    },
    {
        "anchor": "Interplay of anionic quasi-atom and interstitial point defects in\n  electrides: abnormal interstice occupation and colossal charge state of point\n  defects in dense FCC-lithium: Electrides are an emerging class of materials with highly-localized electrons\nin the interstices of a crystal that behave as anions. The presence of these\nunusual interstitial quasi-atom (ISQ) electrons leads to interesting physical\nand chemical properties, and wide potential applications for this new class of\nmaterials. Crystal defects often have a crucial influence on the properties of\nmaterials. Introducing impurities has been proved to be an effective approach\nto improve the properties of a material and to expand its applications.\nHowever, the interactions between the anionic ISQs and the crystal defects in\nelectrides are as yet unknown. Here, dense FCC-Li was employed as an archetype\nto explore the interplay between anionic ISQs and interstitial impurity atoms\nin this electride. This work reveals a strong coupling among the interstitial\nimpurity atoms, the ISQs, and the matrix Li atoms near to the defects. This\ncomplex interplay and interaction mainly manifest as the unexpected tetrahedral\ninterstitial occupation of impurity atoms and the enhancement of electron\nlocalization in the interstices. Moreover, the Be impurity occupying the\noctahedral interstice shows the highest negative charge state (Be8-) discovered\nthus far. These results demonstrate the rich chemistry and physics of this\nemerging material, and provide a new basis for enriching their variants for a\nwide range of applications.",
        "positive": "Conditions for efficient charge generation preceded by energy transfer\n  process in non-fullerene organic solar cells: The minimum driving force strategy is applied to promote the exciton\ndissociation in organic solar cells (OSCs) without significant loss of\nopen-circuit voltage. However, this strategy tends to promote F\\\"orster\nresonance energy transfer (FRET) from the donor to the acceptor (D-A), a\nconsequence generally ignored until recently. In spite of the advances reported\non this topic, the correlation between charge-transfer (CT) state binding\nenergy and driving force remains unclear, especially in the presence of D-A\nFRET. To address this question, we employ a kinetic approach to model the\ncharge separation in ten different D/A blends using non-fullerene acceptors.\nThe model considers the influence of FRET on photoluminescence (PL) quenching\nefficiency. It successfully predicts the measured PL quenching efficiency for D\nor A photoexcitation in those blends, including the ones for which the D-A FRET\nprocess is relevant. Furthermore, the application of the model allows to\nquantifying the fractions of quenching loss associated with charge transfer and\nenergy transfer. Fundamental relationships that controls the exciton\ndissociation was derived evidencing the key roles played by the Marcus inverted\nregime, exciton lifetime and mainly by the correlation between the driving\nforce and binding energy of CT state. Based on those findings, we propose some\nstrategies to maximize the quenching efficiency and minimize energy loss of\nOSCs in the presence of D-A FRET."
    },
    {
        "anchor": "X-ray Anomalous Scattering of Diluted Magnetic Oxide Semiconductors:\n  Possible Evidence of Lattice Deformation for High Temperature Ferromagnetism: We have examined whether the Co ions crystallographically substitute on the\nTi sites in rutile and anatase Ti_{1-x}$Co$_{x}$O$_{2-delta}$ thin films that\nexhibit room-temperature ferromagnetism. Intensities of the x-ray Bragg\nreflection from the films were measured around the $K$-absorption-edge of Co.\nIf the Co ions randomly substitute on the Ti sites, the intensity should\nexhibit an anomaly due to the anomalous dispersion of the atomic scattering\nfactor of Co. However, none of the anatase and rutile samples did exhibit an\nanomaly, unambiguously showing that the Co ions in\nTi$_{1-x}$Co$_{x}$O$_{2-delta}$ are not exactly located at the Ti sites of\nTiO$_2$. The absence of the anomaly is probably caused by a significant\ndeformation of the local structure around Co due to the oxygen vacancy. We have\napplied the same method to paramagnetic Zn$_{1-x}$Co$_{x}$O thin films and\nobtained direct evidence that the Co ions are indeed substituted on the Zn\nsites.",
        "positive": "Structure and thermodynamics of a ferrofluid bilayer: We present extensive Monte Carlo simulations for the thermodynamic and\nstructural properties of a planar bilayer of dipolar hard spheres for a wide\nrange of densities, dipole moments and layer separations. Expressions for the\nstress and pressure tensors of the bilayer system are derived. For all\nthermodynamic states considered the interlayer energy is shown to be attractive\nand much smaller than the intralayer contribution to the energy. It vanishes at\nlayer separations of the order of two hard sphere diameters. The normal\npressure is negative and decays as a function of layer separation $h$ as\n$-1/h^5$. Intralayer and interlayer pair distribution functions and angular\ncorrelation functions are presented. Despite the weak interlayer energy strong\npositional and orientational correlations exist between particles in the two\nlayers."
    },
    {
        "anchor": "Hysteretic electrical transport in BaTiO$_3$/Ba$_{1-x}$Sr$_x$TiO$_3$/Ge\n  heterostructures: We present electrical transport measurements of heterostructures comprised of\nBaTiO$_3$ and Ba$_{1-x}$Sr$_x$TiO$_3$ epitaxially grown on Ge. The Sr-alloying\nimparts compressive strain to the BaTiO$_3$, which enables the thermal\nexpansion mismatch between BaTiO$_3$ and Ge to be overcome to achieve $c$-axis\noriented growth. The conduction bands of BaTiO$_3$ and Ba$_{1-x}$Sr$_x$TiO$_3$\nare nearly aligned with the conduction band of Ge, which facilitates electron\ntransport. Electrical transport measurements through the dielectric stack\nexhibit rectifying behavior and hysteresis, where the latter is consistent with\nferroelectric switching.",
        "positive": "Computational screening of Fe-Ta hard magnetic phases: In this work we perform a systematic calculation of the Fe-Ta phase diagram\nto discover novel hard magnetic phases. By using structure prediction methods\nbased on evolutionary algorithms, we identify two new energetically stable\nmagnetic structures: a tetragonal Fe$_3$Ta (space group 122) and cubic Fe$_5$Ta\n(space group 216) binary phases. The tetragonal structure is estimated to have\nboth high saturation magnetization ($\\mu_0$M$_s$=1.14 T) and magnetocrystalline\nanisotropy (K$_1$=2.17 MJ/m$^3$) suitable for permanent magnet applications.\nThe high-throughput screening of magneto-crystalline anisotropy also reveals\ntwo low energy metastable hard magnetic phases: Fe$_5$Ta$_2$ (space group 156)\nand Fe$_{6}$Ta (space group 194), that may exhibit intrinsic magnetic\nproperties comparable to SmCo$_5$ and Nd$_2$Fe$_{14}$B, respectively."
    },
    {
        "anchor": "Chemical Strain Engineering of MAPbI3 Perovskite Films: This study introduces a new chemical method for controlling the strain in\nmethylammonium lead iodide (MAPbI3) perovskite crystals by varying the ratio of\nPb(Ac)2 and PbCl2 in the precursor solution. To observe the effect on crystal\nstrain, a combination of piezoresponse force microscopy (PFM) and X-ray\ndiffraction (XRD) is used. The PFM images show an increase in the average size\nof ferroelastic twin domains upon increasing the PbCl2 content, indicating an\nincrease in crystal strain. The XRD spectra support this observation with\nstrong crystal twinning features that appear in the spectra. This behaviour is\ncaused by a strain gradient during the crystallization due to different\nevaporation rates of methylammonium acetate and methylammonium chloride as\nrevealed by time-of-flight secondary ion mass spectroscopy (ToF-SIMS) and\ngrazing incidince x-ray diffraction (GIXRD) measurements. Additional\ntime-resolved photoluminescence (TRPL) show an increased carrier lifetime in\nthe MAPbI3 films prepared with higher PbCl2 content, suggesting a decreased\ntrap density in films with larger twin domain structures. The results\ndemonstrate the potential of chemical strain engineering as an easy method for\ncontrolling strain-related effects in lead halide perovskites.",
        "positive": "Separating physically distinct mechanisms in complex infrared plasmonic\n  nanostructures via machine learning enhanced electron energy loss\n  spectroscopy: Low-loss electron energy loss spectroscopy (EELS) has emerged as a technique\nof choice for exploring the localization of plasmonic phenomena at the\nnanometer level, necessitating analysis of physical behaviors from 3D spectral\ndata sets. For systems with high localization, linear unmixing methods provide\nan excellent basis for exploratory analysis, while in more complex systems\nlarge numbers of components are needed to accurately capture the true plasmonic\nresponse and the physical interpretability of the components becomes uncertain.\nHere, we explore machine learning based analysis of low-loss EELS data on\nheterogeneous self-assembled monolayer films of doped-semiconductor\nnanoparticles, which support infrared resonances. We propose a pathway for\nsupervised analysis of EELS datasets that separate and classify regions of the\nfilms with physically distinct spectral responses. The classifications are\nshown to be robust, to accurately capture the common spatiospectral tropes of\nthe complex nanostructures, and to be transferable between different datasets\nto allow high-throughput analysis of large areas of the sample. As such, it can\nbe used as a basis for automated experiment workflows based on Bayesian\noptimization, as demonstrated on the ex situ data. We further demonstrate the\nuse of non-linear autoencoders (AE) combined with clustering in the latent\nspace of the AE yields highly reduced representations of the system response\nthat yield insight into the relevant physics that do not depend on operator\ninput and bias. The combination of these supervised and unsupervised tools\nprovides complementary insight into the nanoscale plasmonic phenomena."
    },
    {
        "anchor": "Symbolic Regression Discovery of New Perovskite Catalysts with High\n  Oxygen Evolution Reaction Activity: Symbolic regression (SR) is an emerging method for building analytical\nformulas to find models that best fit data sets. Here, SR was used to guide the\ndesign of new oxide perovskite catalysts with improved oxygen evolution\nreaction (OER) activities. An unprecedentedly simple descriptor, {\\mu}/t, where\n{\\mu} and t are the octahedral and tolerance factors, respectively, was\nidentified, which accelerated the discovery of a series of new oxide perovskite\ncatalysts with improved OER activity. We successfully synthesized five new\noxide perovskites and characterized their OER activities. Remarkably, four of\nthem, Cs0.4La0.6Mn0.25Co0.75O3, Cs0.3La0.7NiO3, SrNi0.75Co0.25O3, and\nSr0.25Ba0.75NiO3, outperform the current state-of-the-art oxide perovskite\ncatalyst, Ba0.5Sr0.5Co0.8Fe0.2O3 (BSCF). Our results demonstrate the potential\nof SR for accelerating data-driven design and discovery of new materials with\nimproved properties.",
        "positive": "Strong electrical magneto-chiral anisotropy in tellurium: We report the experimental observation of strong electrical magneto-chiral\nanistropy (eMChA) in trigonal tellurium (t-Te) crystals. We introduce the\ntensorial character of the effect and determine several tensor elements and we\npropose a novel intrinsic bandstructure-based mechanism for eMChA which gives a\nreasonable description of the principal results."
    },
    {
        "anchor": "Structural Disorder and Properties of the Stuffed Pyrochlore Ho2TiO5: We report a structural and thermodynamic study of the \"stuffed spin ice\"\nmaterial Ho2TiO5 (i.e., Ho2(Ti1.33Ho0.67)O6.67), comparing samples synthesized\nthrough two different routes. Neutron powder diffraction and electron\ndiffraction reveal that the previously reported defect fluorite phase has\nshort-range pyrochlore ordering, in that there are domains in which the Ho and\nHo/Ti sublattices are distinct. By contrast, a sample prepared through a\nfloating zone method has long range ordering of these sublattices. Despite the\ndifferences in crystal structures, the two versions of Ho2TiO5 display similar\nmagnetic susceptibilities. Field dependent magnetization and measured recovered\nentropies, however, show a difference between the two forms, suggesting that\nthe magnetic properties of the stuffed pyrochlores depend on the local\nstructure.",
        "positive": "Quick X-ray Reflectivity using Monochromatic Synchrotron Radiation for\n  Time-Resolved Applications: We describe and demonstrate a new technique for parallel collection of x-ray\nreflectivity data, compatible with monochromatic synchrotron radiation and flat\nsubstrates, and apply it to the in-situ observation of thin-film growth. The\nmethod employs a polycapillary x-ray optic to produce a converging fan of\nradiation incident onto a sample surface, and an area detector to\nsimultaneously collect the XRR signal over an angular range matching that of\nthe incident fan. Factors determining the range and instrumental resolution of\nthe technique in reciprocal space, in addition to the signal-to-background\nratio, are described in detail. Our particular implementation records\n$\\sim$5\\degree{} in $2\\theta$ and resolves Kiessig fringes from samples with\nlayer thicknesses ranging from 3 to 76 nm. Finally, we illustrate the value of\nthis approach by showing in-situ XRR data obtained with 100 ms time resolution\nduring the growth of epitaxial \\ce{La_{0.7}Sr_{0.3}MnO3} on \\ce{SrTiO3} by\nPulsed Laser Deposition (PLD) at the Cornell High Energy Synchrotron Source\n(CHESS). Compared to prior methods for parallel XRR data collection, ours is\nthe first method that is both sample-independent and compatible with highly\ncollimated, monochromatic radiation typical of 3rd generation synchrotron\nsources. Further, our technique can be readily adapted for use with\nlaboratory-based sources."
    },
    {
        "anchor": "Depth Profile of the Phase Transition of the FeRh Alloy in FeRh/BaTiO3: We report on the depth dependence and technological limits of the phase\ntransition of the iron rhodium alloy as function of temperature, external\nmagnetic and electric fields in the FeRh/BaTiO3 multiferroic, determined by\ngrazing-incidence nuclear resonant scattering measurements. The change of\ntemperature induces a continuous and homogenous antiferromagnetic /\nferromagnetic phase transition through the entire FeRh layer, except in the\nnear substrate region. External magnetic field does not affect this mechanism,\nbut the application of electric field changes it fundamentally (via\npiezoelectric strain): the phase transition of the alloy suddenly propagates\nfrom the substrate up to a height, defined by the combination of temperature\nand external magnetic field, as soon as the applied electric field reaches ~ 20\nkV/m.",
        "positive": "On the abnormal temperature dependent elastic properties of fused silica\n  irradiated by ultrafast lasers: Materials with thermal-invariant elastic properties of materials are of\ninterest for resonant device frequency and dimensional stability of precision\ndevices. Here, we demonstrate that the temperature coefficient of elasticity\n(TCE) of amorphous silica can be locally reduced using femtosecond laser\nirradiation. Notably, a self-organized laser-induced modification shows a\ndecrease of the TCE beyond 50%. The origin of this dramatic decrease is\nattributed to the presence of sub-micron permanent densified zones within the\nfine multi-layers structure of the laser-modified zone."
    },
    {
        "anchor": "Robust Active Site Design of Single Atom Catalysts for Electrochemical\n  Ammonia Synthesis: In this work, we provide a computational methodological framework using the\nsingle-atom systems as an example material class for ammonia synthesis that is\nrobust towards parameter selection. Applying this to Pt$_1$/g-C$_3$N$_4$,\nRu$_1$/g-C$_3$N$_4$, and Fe$_1$/g-C$_3$N$_4$, we generate ensembles of limiting\npotentials, using the ensemble of functionals collected via Bayesian Error\nEstimation Functionals (BEEF), to robustly predict catalytic activity. We then\nextend this to study the scaling between NRR reaction intermediates and use it\nto identify that NNH* as the best descriptor for these relations. In addition,\na procedure to investigate selectivity is outlined, and a more robust way to\nanalyze the selectivity-activity trade-off is presented. For this single-atom\nmaterial class, we find choosing catalysts that lie on the strong binding leg\nof the activity volcano are worth further exploration. Given the ease of\nintegration of the proposed method with minimal additional computational cost,\nwe believe this should become a routine part of analysis workflow for\nmulti-electron electrochemical reactions.",
        "positive": "Electric-field control of the exchange interactions: The impact of an applied electric field on the exchange coupling parameters\nhas been investigated based on first-principles electronic structure\ncalculations by means of the KKR Green function method. The calculations have\nbeen performed for a Fe film, free-standing and deposited on two different\nsubstrates, having 1 monolayer (ML) thickness to minimize the effect of\nscreening of the electric field typical for metallic systems. By comparing the\nresults for the free-standing Fe ML with those for Fe on the various\nsubstrates, we could analyze the origin of the field-induced change of the\nexchange interactions. Compared to the free-standing Fe ML, in particular\nrather pronounced changes have been found for the Fe/Pt(111) system due to the\nlocalized electronic states at the Fe/Pt interface, which are strongly affected\nby the electric field and which play an important role for the Fe-Fe exchange\ninteractions."
    },
    {
        "anchor": "Evidence of the side jump mechanism in the anomalous Hall effect in\n  paramagnets: Persistent confusion has existed between the intrinsic (Berry curvature) and\nthe side jump mechanisms of anomalous Hall effect (AHE) in ferromagnets. We\nprovide unambiguous identification of the side jump mechanism, in addition to\nthe skew scattering contribution in epitaxial paramagnetic Ni$_{34}$Cu$_{66}$\nthin films, in which the intrinsic contribution is by definition excluded.\nFurthermore, the temperature dependence of the AHE further reveals that the\nside jump mechanism is dominated by the elastic scattering.",
        "positive": "Study of the Sorption Properties of Ge20Se80 Thin Films for NO2 Gas\n  Sensing: In this study we investigated the sorption ability of Ge20Se80 thin films\napplied as active layers of quartz crystal microbalance (QCM) for NO2 gas\nsensing. To identify the chalcogenide system appropriate for gas sensing, we\nprovided data for the packing fraction of a number of chalcogenide systems and\ndiscussed their suitability. We performed Raman spectroscopy, X-ray\nphotoelectron spectroscopy (XPS) and atom force microscopy (AFM) measurements\non the thin films both before and after gas absorption, which showed that the\nintroduced gas molecules interact electrostatically with the chalcogen atoms of\nthe host material and initiate some degree of structural changes in it. The\nweight change due to NO2 gas absorption was measured by frequency change of the\nresonator. The absorbed mass increased monotonically with the thickness of\nchalcogenide films and the NO2 gas concentration. At the conditions of our\nexperiment, up to 11.4 ng of the gas was absorbed into 200nm thick Ge20Se80\nfilm at 5000 ppm NO2 concentration. The process of gas molecules absorption is\nfound irreversible at the purging conditions."
    },
    {
        "anchor": "Multiscale Random-Walk Algorithm for Simulating Interfacial Pattern\n  Formation: We present a novel computational method to simulate accurately a wide range\nof interfacial patterns whose growth is limited by a large scale diffusion\nfield. To illustrate the computational power of this method, we demonstrate\nthat it can be used to simulate three-dimensional dendritic growth in a\npreviously unreachable range of low undercoolings that is of direct\nexperimental relevance.",
        "positive": "Nonlinear magnetotransport shaped by Fermi surface topology and\n  convexity in WTe2: The nature of Fermi surface defines the physical properties of conductors and\nmany physical phenomena can be traced to its shape. Although the recent\ndiscovery of a current-dependent nonlinear magnetoresistance in spin-polarized\nnon-magnetic materials has attracted considerable attention in spintronics,\ncorrelations between this phenomenon and the underlying fermiology remain\nunexplored. Here, we report the observation of nonlinear magnetoresistance at\nroom temperature in a semimetal WTe2, with an interesting temperature-driven\ninversion. Theoretical calculations reproduce the nonlinear transport\nmeasurements and allow us to attribute the inversion to temperature-induced\nchanges in Fermi surface convexity. We also report a large anisotropy of\nnonlinear magnetoresistance in WTe2, due to its low symmetry of Fermi surfaces.\nThe good agreement between experiments and theoretical modeling reveals the\ncritical role of Fermi surface topology and convexity on the nonlinear\nmagneto-response. These results lay a new path to explore ramifications of\ndistinct fermiology for nonlinear transport in condensed-matter."
    },
    {
        "anchor": "Unconventional gapless semiconductor in an extended martini lattice in\n  covalent honeycomb materials: We study characteristic electronic structures in an extended martini lattice\nmodel and propose its materialization in $\\pi$-electron networks constructed by\ndesignated chemisorption on graphene and silicene. By investigating the minimal\ntight-binding model, we reveal rich electronic structures tuned by the ratio of\nhopping parameters, ranging from the band insulator to the unconventional\ngapless semiconductor. Remarkably, the unconventional gapless semiconductor is\ncharacterized by a flat band at the Fermi level. Further, the density\nfunctional theory calculations for candidate materials reveal that the\ncharacteristic electronic structures can be realized by designated\nchemisorption or chemical substitution on graphene and silicene, and that the\nelectronic structure near the Fermi level is tunable by the choice of the\natomic species of adsorbed atoms. Our results open the way to search exotic\nelectronic structures and their functionalities induced by an extended martini\nlattice.",
        "positive": "Photo luminescence of Cooper pairs in a naturally occurring\n  heretostructure K$_{0.75}$Fe$_{1.75}$Se$_{2}$: Combining superconductor and semiconductors in nanostructure junctions was a\nchallenging technological problem that attracted attention for long time [van\nWees]. The radiative recombination of Cooper pairs was demonstrated, using a\nNb/n-InGaAs/p-InP heterostructure [EL_Hayashi, PL_Hayashi], called Cooper pair\nLED [PL_Suemune, R_Suemune]. It has been suggested that the junction could\nproduce entangled photon pairs [Benson, Gywat] needed for quantum information\nprocessing and communication. Here we demonstrate an enhanced radiative\nrecombination of electron Copper pairs in inhomogeneous\nK$_{0.75}$Fe$_{1.75}$Se$_{2}$ (KFS) subjected to laser light upon cooling below\nsuperconducting transition temperature $T_{c}$ 28 K. The observation of this\nphenomena is possible due to fulfillment of the following three conditions: (1)\nPhase separation in superconducting KFS crystals is realized via naturally\noccurring heterostructure [mic_Charnukha, TEM_Wang]; (2) Partial Fe-vacancy\nordered $n$-type semiconducting regions, sandwiched between Fe-vacancy free SC\nand vacancy-ordering AFM structure, forming active layers. The electronic\nstructure of those active layer is tuned to induce Cooper pairs by the\nproximity effect [de Gennes] and/or to accept Cooper pair tunneling from the SC\nphase. In the active layer, the electron Cooper pair can radiatively recombine\nwith two p-type holes [Asano] produced by laser photoexcitation; (3) In KFS\nnature provides at least 10$^{9}$ SC/$n$-type semiconducting/AFM insulating\njunctions per cm$^{3}$. For laser excitation energy of 1.92 eV ($\\lambda\n$=647.1 nm) and power 0.68 mW focused to the spot of 40x80 $\\mu $m$^{2}$ the\nestimated internal quantum efficiency of the natural heterostructure at 10 K in\nthe luminescence range of 700 to 1300 nm is close to 100% and is likely limited\nby availability of the $p$-type holes."
    },
    {
        "anchor": "Multi-Task Mixture Density Graph Neural Networks for Predicting Cu-based\n  Single-Atom Alloy Catalysts for CO2 Reduction Reaction: Graph neural networks (GNNs) have drawn more and more attention from material\nscientists and demonstrated a high capacity to establish connections between\nthe structure and properties. However, with only unrelaxed structures provided\nas input, few GNN models can predict the thermodynamic properties of relaxed\nconfigurations with an acceptable level of error. In this work, we develop a\nmulti-task (MT) architecture based on DimeNet++ and mixture density networks to\nimprove the performance of such task. Taking CO adsorption on Cu-based\nsingle-atom alloy catalysts as an illustration, we show that our method can\nreliably estimate CO adsorption energy with a mean absolute error of 0.087 eV\nfrom the initial CO adsorption structures without costly first-principles\ncalculations. Further, compared to other state-of-the-art GNN methods, our\nmodel exhibits improved generalization ability when predicting catalytic\nperformance of out-of-domain configurations, built with either unseen substrate\nsurfaces or doping species. We show that the proposed MT GNN strategy can\nfacilitate catalyst discovery.",
        "positive": "Modeling of porous lithium metal electrodes: turning the Li-dendrite\n  problem around: The properties of rechargeable lithium-ion batteries are determined by the\nelectrochemical and kinetic properties of their constituent materials as well\nas by their underlying microstructure. Microstructural design can be leveraged\nto achieve a leap in performance and durability. Here we investigate a porous\nelectrode structure, as a strategy to increase the surface area, and provide\nstructural stability for Li-metal anodes. The porous architecture consists of a\nmixed electron/ion conductor that function as a scaffold for lithium metal\ndeposition. A new finite element model was developed to simulate the large\ntopological changes associated with Li plating/stripping. This model is used to\npredict the current density distribution as a function of material and\nstructural properties. A dimensionless quantity that combines Li-ion\nconductivity, surface impedance and average pore size is shown to be a good\nindicator to predict the peak current density. Preventing current localization\nat the separator reduces the risk of cell shorting. The analyses show that the\npeak current scales as $(hG)^{1/2}$, where $h$ is the ratio between surface and\nbulk conductivity and $G$ is the average pore size. Stability analyses suggest\nthat the growth is morphologically stable, and that confining Li-plating into\npores can enable high-energy density solid-state batteries. In addition to\noptimizing porous electrodes design, this finite element method can be extended\nto studying other Li-battery structures."
    },
    {
        "anchor": "Stability and electronic properties of small BN nanotubes: We report the stability and electronic structures of the boron nitride\nnanotubes (BNNTs) with diameters below 4 A by semi-empirical quantum mechanical\nmolecular dynamics simulations and ab initio calculations. Among them (3,0),\n(3,1), (2,2), (4,0), (4,1) and (3,2) BNNTs can be stable well over room\ntemperature. These small BNNTs become globally stable when encapsulated in a\nlarger BNNT. It is found that the energy gaps and work functions of these small\nBNNTs are strongly dependent on their chirality and diameters. The small zigzag\nBNNTs become desirable semiconductors and have peculiar distribution of nearly\nfree electron states due to strong hybridization effect. When such a small BNNT\nis inserted in a larger one, the energy gap of the formed double-walled BNNT\ncan even be much reduced due to the coupled effect of wall buckling difference\nand NFE-pi hybridization.",
        "positive": "Multiple Spin-Phonon Relaxation Pathways in a Kramer Single-Ion Magnet: We present a first-principles investigation of spin-phonon relaxation in a\nmolecular crystal of Co(II) single-ion magnets. Our study combines electronic\nstructure calculations with machine-learning force fields and unravels the\nnature of both the Orbach and the Raman relaxation channels in terms of\natomistic processes. We find that although both mechanisms are mediated by the\nexcited spin states, the low temperature spin dynamics is dominated by phonons\nin the THz energy range, which partially suppress the benefit of having a large\nmagnetic anisotropy. This study also determines the importance of\nintra-molecular motions for both the relaxation mechanisms and paves the way to\nthe rational design of a new generation of single-ion magnets with tailored\nspin-phonon coupling."
    },
    {
        "anchor": "Density functional theory: Density functional theory (DFT) is an essential building block for modern\ntheoretical physics, chemistry, and engineering, especially those concerning\nelectronic properties. Through decades of development, various program packages\nfor first-principles electronic structure calculation are now available. Their\nsophisticated interfaces allow users to apply DFT to actual systems, even\nwithout knowing the theory. It is hence becoming more and more important to\nrecall the fundamentals of how DFT enables accurate calculations. This article\nattempts to provide such knowledge with a minimal overview of DFT -- its basic\nfoundation, relations to observable electronic and nuclear dynamical\nproperties, and some of its cutting-edge applications.",
        "positive": "Magnetic properties of 3d-impurities substituted in GaAs: We have calculated the magnetic properties of substituted 3d-impurities\n(Cr-Ni) in a GaAs host by means of first principles electronic structure\ncalculations. We provide a novel model explaining the ferromagnetic long rang\norder of III-V dilute magnetic semiconductors. The origin of the ferromagnetism\nis shown to be due to delocalized spin-uncompensated As dangling bond\nelectrons. Besides the quantitative prediction of the magnetic moments, our\nmodel provides an understanding of the halfmetallicity, and the raise of the\ncritical temperature with the impurity concentration."
    },
    {
        "anchor": "Zero- and one-dimensional magnetic traps for quasi-particles: We investigate the possibility of trapping quasi-particles possessing spin\ndegree of freedom in hybrid structures. The hybrid system we are considering\nhere is composed of a semi-magnetic quantum well placed a few nanometers below\na ferromagnetic micromagnet. We are interested in two different micromagnet\nshapes: cylindrical (micro-disk) and rectangular geometry. We show that in the\ncase of a micro-disk, the spin object is localized in all three directions and\ntherefore zero-dimensional states are created, and in the case of an elongated\nrectangular micromagnet, the quasi-particles can move freely in one direction,\nhence one-dimensional states are formed. After calculating profiles of the\nmagnetic field produced by the micromagnets, we analyze in detail the possible\nlight absorption spectrum for different micromagnet thicknesses, and different\ndistances between the micromagnet and the semimagnetic quantum well. We find\nthat the discrete spectrum of the localized states can be detected via\nspatially-resolved low temperature optical measurement.",
        "positive": "Effects of the grain size and shape on the flow stress: A dislocation\n  dynamics study: Dislocation dynamics simulation is used to investigate the effect of grain\nsize and grain shape on the flow stress in model copper grains. We consider\ngrains of 1.25-10 $\\mu$m size, three orientations (<135>, <100> and <111>) and\nthree shapes (cube, plate and needles). Two types of periodic aggregates with\none or four grains are simulated to investigate different dislocation flux at\ngrain boundaries. It is shown that in all cases the flow stress varies linearly\nwith the inverse of the square root of the grain size, with a proportionality\nfactor varying strongly with the grain orientation and shape. Simulation\nresults are discussed in the light of other simulation results and experimental\nobservations. Finally, a simple model is proposed to account for the grain\nshape influence on the grain size effect."
    },
    {
        "anchor": "Observation of spin-orbit magnetoresistance in metallic thin films on\n  magnetic insulators: A magnetoresistance effect induced by the Rashba spin-orbit interaction was\npredicted, but not yet observed, in bilayers consisting of normal metal and\nferromagnetic insulator. Here, we present an experimental observation of this\nnew type of spin-orbit magnetoresistance (SOMR) effect in a bilayer structure\nCu[Pt]/Y3Fe5O12 (YIG), where the Cu/YIG interface is decorated with nanosize Pt\nislands. This new MR is apparently not caused by the bulk spin-orbit\ninteraction because of the negligible spin-orbit interaction in Cu and the\ndiscontinuity of the Pt islands. This SOMR disappears when the Pt islands are\nabsent or located away from the Cu/YIG interface, therefore we can\nunambiguously ascribe it to the Rashba spin-orbit interaction at the interface\nenhanced by the Pt decoration. The numerical Boltzmann simulations are\nconsistent with the experimental SOMR results in the angular dependence of\nmagnetic field and the Cu thickness dependence. Our finding demonstrates the\nrealization of the spin manipulation by interface engineering.",
        "positive": "Strain-induced shift in the elastically soft direction of epitaxially\n  grown fcc metals: The theory of epitaxial strain energy is extended beyond the harmonic\napproximation to account for large film/substrate lattice mismatch. We find\nthat for fcc noble metals (i) directions <001> and <111> soften under tensile\nbiaxial strain (unlike zincblende semiconductors) while (ii) <110> and <201>\nsoften under compressive biaxial strain. Consequently, (iii) upon sufficient\ncompression <201> becomes the softest direction (lowest elastic energy), but\n(iv) <110> is the hardest direction for large tensile strain. (v) The dramatic\nsoftening of <001> in fcc noble metals upon biaxial tensile strain is caused by\nsmall fcc/bcc energy differences for these materials. These results can be used\nin selecting the substrate orientation for effective epitaxial growth of pure\nelements and A/sub p/B/sub q/ superlattices, as well as to explain the shapes\nof coherent precipitates in phase separating alloys."
    },
    {
        "anchor": "Theory of resonance energy transfer involving nanocrystals: the role of\n  high multipoles: A theory for the fluorescence resonance energy transfer (FRET) between a pair\nof semiconducting nanocrystal quantum dots is developed. Two types of\ndonor-acceptor couplings for the FRET rate are described: dipole-dipole (d-d)\nand the dipole-quadrupole (d-q) coupling. The theory builds on a simple\neffective mass model which is used to relate the FRET rate to measureable\nquantities such as the nanocrystal size, fundamental gap, effective mass,\nexciton radius and dielectric constant. We discuss the relative contribution to\nthe FRET rate of the different multipole terms, the role of strong to weak\nconfinement limits, and the effects of nanocrystal siz-es.",
        "positive": "Kinetic Monte Carlo simulations of proton conductivity: The kinetic Monte Carlo method is used to model the dynamic properties of\nproton diffusion in anhydrous proton conductors. The results have been\ndiscussed with reference to a two-step process called the Grotthuss mechanism.\nThere is a widespread belief that this mechanism is responsible for fast proton\nmobility. We showed in detail that the relative frequency of reorientation and\ndiffusion processes is crucial for the conductivity. Moreover, the current\ndependence on proton concentration has been analyzed. In order to test our\nmicroscopic model the proton transport in polymer electrolyte membranes based\non benzimidazole C7H6N2 molecules is studied."
    },
    {
        "anchor": "Biaxial strain tuned thermoelectric properties in monolayer\n  $\\mathrm{PtSe_2}$: Strain engineering is a very effective method to tune electronic, optical,\ntopological and thermoelectric properties of materials. In this work, we\nsystematically study biaxial strain dependence of electronic structures and\nthermoelectric properties (both electron and phonon parts) of monolayer\n$\\mathrm{PtSe_2}$ with generalized gradient approximation (GGA) plus spin-orbit\ncoupling (SOC) for electron part and GGA for phonon part. Calculated results\nshow that compressive or tensile strain can induce conduction band minimum\n(CBM) or valence band maximum (VBM) transition, which produces important\neffects on Seebeck coefficient. It is found that compressive or tensile strain\ncan induce significantly enhanced n- or p-type Seebeck coefficient at the\ncritical strain of CBM or VBM transition, which can be explained by\nstrain-induced band convergence. Another essential strain effect is that\ntensile strain can produce significantly reduced lattice thermal conductivity,\nand the room temperature lattice thermal conductivity at the strain of -4.02\\%\ncan decrease by about 60\\% compared to unstrained one, which is very favorable\nfor high $ZT$. To estimate efficiency of thermoelectric conversion, the figure\nof merit $ZT$ can be obtained by empirical scattering time $\\tau$. Calculated\n$ZT$ values show that strain indeed is a very effective strategy to achieve\nenhanced thermoelectric properties, especially for p-type doping. Tuning\nthermoelectric properties with strain also can be applied to other\nsemiconducting transition-metal dichalcogenide monolayers $\\mathrm{MX_2}$\n(M=Zr, Hf, Mo, W and Pt; X=S, Se and Te).",
        "positive": "Electron-hole transport and photovoltaic effect in gated MoS2 Schottky\n  junctions: Atomically thin MoS2 has recently emerged as a very attractive material for\nnanoscale optoelectronic devices. While n-type transport in MoS2 devices has\nbeen demonstrated, hole conduction has been more challenging. Here we show\nwork-function engineering to be an effective approach for controlling the\npolarity of MoS2 devices. Gated multi-layer MoS2 transistors with Au\nsource/drain contacts exhibit n-type operation, while those with Pd contacts\nare shown to have p-type behavior. Devices with one Au and one Pd contact\nexhibit asymmetric ambipolar behavior and diode characteristics over a wide\nrange of gate voltage, as well as a sizable photovoltaic effect. We argue that\nthe photovoltaic effect arises from the built-in potential of the space charge\naccumulated at the source and drain contacts."
    },
    {
        "anchor": "Negative differential resistance and pulsed current induced multi-level\n  resistivity switching in charge ordered and disordered manganites: We have investigated direct and pulsed current induced electroresistance in\ntwo manganites with different electronic and magnetic ground states:\ncharge-orbital ordered 50 % Ca doped NdMnO3 and 50 % Mn doped LaNiO3. It has\nbeen shown that negative differential resistance observed at high current\ndensity in these compounds is related to Joule heating. However, bi-level and\nmulti-level resistivity switching induced by variations in pulse width and\npulse period at low current density can not be attributable to Joule heating\nalone. We discuss possible origins.",
        "positive": "Chen's derivative rule revisited: Role of tip-orbital interference in\n  STM: On the occasion of its 25th anniversary, we revise Chen's derivative rule for\nelectron tunneling [C.J. Chen, Phys. Rev. B 42, 8841 (1990)] for the purpose of\ncomputationally efficient simulations of scanning tunneling microscopy (STM)\nbased on first principles electronic structure data. The revised model allows\nthe weighting of tunneling matrix elements of different tip orbital characters\nby an arbitrary energy independent choice or based on energy dependent\nweighting coefficients obtained by an expansion of the tip single electron\nwavefunctions/density of states projected onto the tip apex atom. Tip-orbital\ninterference in the STM junction is included in the model by construction and\ncan be analyzed quantitatively. As a further advantage, arbitrary tip\ngeometrical orientations are included in the revised model by rotating the\ncoordinate system of the tip apex using Euler angles and redefining the\nweighting coefficients of the tunneling matrix elements. We demonstrate the\nreliability of the model by applying it to two functionalized surfaces of\nrecent interest where quantum interference effects play an important role in\nthe STM imaging process: N-doped graphene and a magnetic Mn2H complex on the\nAg(111) surface. We find that the proposed tunneling model is 25 times faster\nthan the Bardeen method concerning computational time, while maintaining good\nagreement. Our results show that the electronic structure of the tip has a\nconsiderable effect on STM images, and the Tersoff-Hamann model does not always\nprovide sufficient results in view of quantum interference effects. For both\nstudied surfaces we highlight the importance of interference between s and pz\ntip orbitals that can cause a significant contrast change in the STM images."
    },
    {
        "anchor": "Laser-induced ultrafast transport and demagnetization at the earliest\n  time: First-principles and real-time investigation: Here we carry out a first-principles time-dependent calculation to\ninvestigate how fast electrons actually move under laser excitation and how\nlarge the electron transport affects demagnetization on the shortest time\nscale. To take into account the transport effect, we implement the intraband\ntransition in our theory. In the bulk fcc Ni, we find the effect of the spin\ntransport on the demagnetization is extremely small, no more than 1\\%. The\ncollective electron velocity in Ni is 0.4 $\\rm \\AA/fs$, much smaller than the\nFermi velocity, and the collective displacement is no more than 0.1 $\\rm \\AA$.\nBut this does not mean that electrons do not travel fast; instead we find that\nelectron velocities at two opposite crystal momenta cancel each other. We\nfollow the $\\Gamma$-X line and find a huge dispersion in the velocities in the\ncrystal momentum space. In the Fe/W(110) thin film, the overall demagnetization\nis larger than Ni, and the Fermi velocity is higher than Ni. However, the\neffect of the spin transport is still small in the Fe/W(110) thin film. Based\non our numerical results and existing experimental findings, we propose a\ndifferent mechanism that can explain two latest experimental results. Our\nfinding sheds new light on the effect of ballistic transport on\ndemagnetization.",
        "positive": "Calculation of magnetic exchange couplings in S=3/2 honeycomb system\n  Bi$_3$Mn$_4$O$_{12}$(NO$_3$)} from first principles: Absence of magnetic ordering in Bi$_3$Mn$_4$O$_{12}$(NO$_3$), (BMNO) which\nhas a magnetic subsystem that consists of honeycomb bi-layers of Mn$^{4+}$ ions\nwith spin S=3/2, has raised the expectation that its ground state is strongly\nfrustrated due to longer-range antiferromagnetic interactions. We calculate the\nmagnetic exchange coupling constants of the BMNO complex within a density\nfunctional approach and find that the dominating interactions between Mn spins\nare the antiferromagnetic nearest-neighbor $J_1$ and interlayer interaction\n$J_c$. The largest interaction is $J_c$, which substantially exceeds $J_1$.\nLonger-range interactions are antiferromagnetic, but only weakly frustrating."
    },
    {
        "anchor": "No clear evidence of ferroelectric order in tensile-strained\n  anatase-TiO2 thin films grown on (110) NdGaO3 substrates: Very recently there was a report of the discovery using piezoelectric force\nmicroscopy (PFM) of a switchable ferroelectric polarization in 1.6 % tensile\nstrained TiO2 thin film with anatase crystal structure (see N. Deepak et al.\nAdv. Funct. Mater. 2014, 24, 2844). The polarization disappeared only above 450\nK, which was assigned as a Curie temperature, Tc. Here we have performed X-ray\ndiffraction, second-harmonic generation (SHG) and infrared investigations of\nthe same films. Phonon frequencies exhibit less than a 10 % shift down with the\ntensile strain and no anomaly near expected TC. SHG experiment did not reveal\nany signal characteristic for inversion symmetry breaking, as expected in\nferroelectric phase, and the c-lattice parameter exhibits no anomaly on heating\nnear expected TC. Based on these results, we can summarize that we were not\nable to confirm the previously discovered ferroelectricity in tensile-strained\nanatase-TiO2 thin films.",
        "positive": "Ferromagnet/Semiconductor/Ferromagnet Hybrid Trilayers grown using solid\n  phase epitaxy: The direct growth of semiconductors over metals by molecular beam epitaxy is\na difficult task due to the large differences in crystallization energy between\nthese types of materials. This aspect is problematic in the context of\nspintronics, where coherent spin-injection must proceed via ballistic transport\nthrough sharp interfacial Schottky barriers. We report the realization of\nsingle-crystalline ferromagnet/semiconductor/ferromagnet hybrid trilayers using\nsolid-phase epitaxy, with combinations of Fe3Si, Co2FeSi, and Ge. The slow\nannealing of amorphous Ge over Fe3Si results in a crystalline filmlm identified\nas FeGe2. When the annealing is performed over Co2FeSi, reflected high-energy\nelectron diffraction and X-ray diffraction indicate the creation of a different\ncrystalline Ge(Co,Fe,Si) compound, which also preserves growth orientation. It\nwas possible to observe independent magnetization switching of the\nferromagnetic layers in a Fe3Si/FeGe2/Co2FeSi sample, thanks to the different\ncoercive fields of the two metals and to the quality of the interfaces. This\nresult is a step towards the implementation of vertical spin-selective\ntransistor-like devices."
    },
    {
        "anchor": "Alloying-related trends from first principles: An application to the\n  Ti--Al--X--N system: Tailoring and improving material properties by alloying is a long-known and\nused concept. Recent research has demonstrated the potential of ab initio\ncalculations in understanding the material properties at the nanoscale. Here we\npresent a systematic overview of alloying trends when early-transition metals\n(Y, Zr, Nb, Hf, Ta) are added in the Ti$_{1-x}$Al$_x$N system, routinely used\nas a protective hard coating. The alloy lattice parameters tend to be larger\nthan the corresponding linearised Vegard's estimation, with the largest\ndeviation more than 2.5% obtained for Y$_{0.5}$Al$_{0.5}$N. The chemical\nstrengthening is most pronounced for Ta and Nb, although also causing smallest\nelastic distortions of the lattice due to their atomic radii being comparable\nwith Ti and Al. This is further supported by the analysis of the electronic\ndensity of states. Finally, mixing enthalpy as a measure of the driving force\nfor decomposition into the stable constituents, is enhanced by adding Y, Zr and\nNb, suggesting that the onset of spinodal decomposition will appear in these\ncases for lower thermal loads than for Hf and Ta alloyed Ti$_{1-x}$Al$_x$N.",
        "positive": "Reading the structure of amorphous materials from diffraction patterns\n  and neighbor distribution functions: An exact analytical expression for the static structure factor $S(k)$ in\ndisordered materials is derived from Fourier transformed neighbor distribution\ndecompositions in real space, and permits to reconstruct the function $S(k)$ in\nan iterative fashion. The result is successfully compared to experimental data\nof archetypal glasses or amorphous materials (GeS$_2$, As$_2$Se$_3$, GeTe), and\nlinks quantitatively knowledge of structural information on short and\nintermediate -range order with the motifs found on the diffraction patterns in\nreciprocal space. The approach furthermore reveals that only a limited number\nof neighbor shells is sufficient to reasonably describe the structure factor\nfor $k>$2~\\AA$^{-1}$. In the limit of the high momentum transfer, the\noscillation characteristics of the interference function are related with new\ninformations on the short-range order of disordered materials."
    },
    {
        "anchor": "Neo-Hookean fiber composites undergoing finite out-of-plane shear\n  deformations: The response of a neo-Hookean fiber composite undergoing finite out-of-plane\nshear deformation is examined. To this end an explicit close form solution for\nthe out-of-plane shear response of a cylindrical composite element is\nintroduced. We find that the overall response of the cylindrical composite\nelement can be characterized by a fictitious homogeneous neo-Hookean material.\nAccordingly, this macroscopic response is identical to the response of a\ncomposite cylinder assemblage. The expression for the effective shear modulus\nof the composite cylinder assemblage is identical to the corresponding\nexpression in the limit of small deformation elasticity, and hence also to the\nexpression for the Hashin-Shtrikman bounds on the out-of-plane shear modulus.",
        "positive": "Magneto-optical imaging of voltage-controlled magnetization\n  reorientation: We study the validity and limitations of a macrospin model to describe the\nvoltage-controlled manipulation of ferromagnetic magnetization in nickel thin\nfilm/piezoelectric actuator hybrid structures. To this end, we correlate\nsimultaneously measured spatially resolved magneto-optical Kerr effect imaging\nand integral magnetotransport measurements at room temperature. Our results\nshow that a macrospin approach is adequate to model the magnetoresistance as a\nfunction of the voltage applied to the hybrid, except for a narrow region\naround the coercive field - where the magnetization reorientation evolves via\ndomain effects. Thus, on length scales much larger than the typical magnetic\ndomain size, the voltage control of magnetization is well reproduced by a\nsimple Stoner-Wohlfarth type macrospin model."
    },
    {
        "anchor": "Long-range nature of surface-enhanced Raman scattering: The long-range action of surface-enhanced Raman scattering (SERS) is probed\nvia distance-dependent measurements of molecular Raman spectra. To this end,\nidentical SERS substrates composed of irregular silver nanoisland arrays were\ncovered by dielectric spacer layers with variable thickness, and the strength\nof the SERS signal produced from analyte molecules deposited on top of the\nstructure was analyzed. The obtained distance dependence of the signal strength\nexhibited a shelf-like behavior up to 30 nm away from the enhancing surface and\nthen rapidly decreased further away. Thus, the observed behavior of the\nelectromagnetic mechanism of SERS enhancement in metal island films contradicts\nthe widely accepted picture of extremely rapid (2-3nm) decay of\nSERS-enhancement of 2D nanoparticle ensembles. Because of the observed steady\nenhancement factors at distances of ~30 nm from the surface, SERS can be used\nfor probing the spectra of macromolecules or other objects relatively distant\nfrom the metal surface.",
        "positive": "Halogenation induced transition of superconductor-to-semiconductor in\n  MXene-like MOene with direct band gap and long carrier lifetime: Traditional MXenes with intriguing mechanical and electronic properties,\ntogether with the fertilities of elemental compositions and chemical\ndecorations have aroused much attentions. However, the semiconducting traits\nwith direc band gap are extremetely rare among reported MXenes. Thus,\nbroadening the family of MXene beyond carbides and nitrides with unique\nbehaviors is still an extraordinary and fascinating field."
    },
    {
        "anchor": "Melting slope of MgO from molecular dynamics and density functional\n  theory: We combine density functional theory (DFT) with molecular dynamics\nsimulations based on an accurate atomistic force field to calculate the\npressure derivative of the melting temperature of magnesium oxide at ambient\npressure - a quantity for which a serious disagreement between theory and\nexperiment has existed for almost 15 years. We find reasonable agreement with\nprevious DFT results and with a very recent experimental determination of the\nslope. We pay particular attention to areas of possible weakness in theoretical\ncalculations and conclude that the long-standing discrepancy with experiment\ncould only be explained by a dramatic failure of existing density functionals\nor by flaws in the original experiment.",
        "positive": "Free energy generalization of the Peierls potential in iron: In body-centered cubic (bcc) crystals, ${1}{2}111$ screw dislocations exhibit\nhigh intrinsic lattice friction as a consequence of their non-planar core\nstructure, which results in a periodic energy landscape known as the Peierls\npotential, $U_P$. The main features determining plastic flow, including its\nstress and temperature dependences, can be derived directly from this\npotential, hence its importance. In this Letter, we use thermodynamic\nintegration to provide a full thermodynamic extension of $U_P$ for bcc Fe. We\ncompute the Peierls free energy path as a function of stress and temperature\nand show that the critical stress vanishes at 700K, supplying the qualitative\nelements that explain plastic behavior in the athermal limit."
    },
    {
        "anchor": "Monte Carlo simulation of pressure-induced phase transitions in\n  spin-crossover materials: Pressure-induced phase transitions of spin-crossover materials were simulated\nby a Monte Carlo simulation in the constant pressure ensemble for the first\ntime. Here, as the origin of the cooperative interaction, we adopt elastic\ninteraction among the distortions of the lattice due to the difference of the\nmolecular sizes in different spin states, i.e., the high spin (HS) state and\nthe low spin (LS) state. We studied how the temperature dependence of the\nordering process changes with the pressure, and we obtained a standard sequence\nof temperature dependences that has been found in changing other parameters\nsuch as strength of the ligand field (S. Miyashita et al., Prog. Theor. Phys.\n\\textbf{114}, 719 (2005)). Various effects of pressure on the spin-crossover\nordering process are examined from a unified point of view.",
        "positive": "Neutron spectroscopy and magnetic relaxation of the Mn$_6$ nanomagnets: Inelastic neutron scattering has been used to determine the microscopic\nHamiltonian describing two high-spin variants of the high-anisotropy Mn$_6$\nnanomagnet. The energy spectrum of both systems is characterized by the\npresence of several excited total-spin multiplets partially overlapping the\nS=12 ground multiplet. This implies that the relaxation processes of these\nmolecules are different from those occurring in prototype giant-spin\nnanomagnets. In particular, we show that both the height of the energy barrier\nand resonant tunnelling processes are greatly influenced by low-lying excited\ntotal-spin multiplets."
    },
    {
        "anchor": "Near-forward Raman study of a phonon-polariton reinforcement regime in\n  the Zn(Se,S) alloy: We investigate by near-forward Raman scattering a presumed reinforcement of\nthe (A-C,B-C)-mixed phonon-polariton of a A1-xBxC zincblende alloy when\nentering its longitudinal optical (LO-)regime near the Brillouin zone centre\n{\\Gamma}, as predicted within the formalism of the linear dielectric response.\nA choice system to address such issue is ZnSe0.68S0.32 due to the moderate\ndispersion of its refractive index in the visible range, a sine qua non\ncondition to bring the phonon-polariton insight near {\\Gamma}. The LO-regime is\nactually accessed by using the 633.0 nm laser excitation, testified by the\nstrong emergence of the (Zn-Se,Zn-S)-mixed phonon-polariton at ultimately small\nscattering angles.",
        "positive": "Fast predictions of lattice energies by continuous isometry invariants\n  of crystal structures: Crystal Structure Prediction (CSP) aims to discover solid crystalline\nmaterials by optimizing periodic arrangements of atoms, ions or molecules. CSP\ntakes weeks of supercomputer time because of slow energy minimizations for\nmillions of simulated crystals. The lattice energy is a key physical property,\nwhich determines thermodynamic stability of a crystal but has no simple\nanalytic expression. Past machine learning approaches to predict the lattice\nenergy used slow crystal descriptors depending on manually chosen parameters.\nThe new area of Periodic Geometry offers much faster isometry invariants that\nare also continuous under perturbations of atoms. Our experiments on simulated\ncrystals confirm that a small distance between the new invariants guarantees a\nsmall difference of energies. We compare several kernel methods for\ninvariant-based predictions of energy and achieve the mean absolute error of\nless than 5kJ/mole or 0.05eV/atom on a dataset of 5679 crystals."
    },
    {
        "anchor": "Orbital tomography of hybridized and dispersing molecular overlayers: With angle resolved photoemission experiments and \\emph{ab-initio} electronic\nstructure calculations, the pentacene monolayers on Ag(110) and Cu(110) are\ncompared and contrasted allowing the molecular orientation and an unambiguous\nassignment of emissions to specific orbitals to be made. On Ag(110), the\norbitals remain essentially isolated-molecule like, while strong\nsubstrate-enhanced dispersion and orbital modification are observed upon\nadsorption on Cu(110). We show how the photoemission intensity of extended\nsystems can be simulated and that it behaves essentially like that of the\nisolated molecule modulated by the band dispersion due to intermolecular\ninteractions.",
        "positive": "decryst: an efficient software suite for structure determination from\n  powder diffraction: Presented here is decryst, a software suite for structure determination from\npowder diffraction, which uses the direct space method, and is able to apply\nanti-bump constraints automatically and efficiently during the procedure of\nglobal optimisation using the crystallographic collision detection algorithm in\narXiv:1708.03180. decryst employs incremental computation in its global\noptimisation cycles, which results in dramatic performance enhancement; it is\nalso designed with parallel and distributed computing in mind, allowing for\neven better performance by simultaneous use of multiple processors. decryst is\nfree and open source software, and can be obtained at\nhttps://gitlab.com/CasperVector/decryst/; it strives to be simple yet flexible,\nin the hope that the underlying techniques could be adopted in more\ncrystallographic applications."
    },
    {
        "anchor": "Semirelativity in Semiconductors: a Review: Analogy between behavior of electrons in narrow-gap semiconductors (NGS) and\nrelativistic electrons is reviewed. Energy bands in NGS correspond to special\nrelativity, the latter is analogous to two-band k.p description for NGS.\nMaximum electron velocity in NGS is u=(okolo)1x 10^8 cm/s corresponding to the\nlight velocity. An effective mass of electrons in semiconductors is introduced\nrelating their velocity to quasimomentum. This mass depends on energy similarly\nto the mass of relativistic electrons. In Hg_(1-x)Cd_(x)Te alloys one can reach\nvanishing energy gap at which electrons and light holes are 3D massless Dirac\nfermions. Wavelength lam_z is defined for NGS, in analogy to the Compton\nwavelength, lam_z is around tens of Angstroms in semiconducting materials, in\nagreement with tunneling experiments. Interband electron tunneling in NGS is in\nclose analogy to tunneling between negative and positive energies of the Dirac\nequation. Relativistic analogy holds for orbital and spin properties of\nelectrons in an external magnetic field. The spin magnetic moment of both NGS\nelectrons and relativistic electrons approaches zero with increasing energy.\nElectrons in crossed electric and magnetic fields are described. It is the\nsemirelativistic two-band description that gives a correct account of\nexperiments in this situation. A transverse Doppler shift is observed in\ncrossed fields indicating that there exists a time dilatation between an\nelectron and an observer. Phenomenon of Zitterbewegung (ZB, trembling motion)\nfor semiconductor electrons follows an analogy to free relativistic electrons.\nGraphene, carbon nanotubes, topological insulators illustrate extreme\nsemirelativistic regime. Approximations and restrictions of the relativistic\nanalogy are emphasized. It is often easier to observe semirelativistic effects\nin semiconductors than relativistic effects in vacuum.",
        "positive": "Spectroscopy of phonons and spin torques in magnetic point contacts: Phonon spectroscopy is used to investigate the mechanism of current-induced\nspin torques in nonmagnetic/ferromagnetic (N/F) point contacts. Magnetization\nexcitations observed in the magneto-conductance of the point contacts are\npronounced for diffusive and thermal contacts, where the electrons experience\nsignificant scattering in the contact region. We find no magnetic excitations\nin highly ballistic contacts. Our results show that impurity scattering at the\nN/F interface is the origin of the new single-interface spin torque effect."
    },
    {
        "anchor": "Variational calculation of many-body wave functions and energies from\n  density-functional theory: A generating coordinate is introduced into the exchange-correlation\nfunctional of density-functional theory (DFT). The many-body wave function is\nrepresented as a superposition of Kohn-Sham (KS) Slater determinants arising\nfrom different values of the generating coordinate. This superposition is used\nto variationally calculate many-body energies and wave functions from solutions\nof the KS equation of DFT. The method works for ground and excited states, and\ndoes not depend on identifying the KS orbitals and energies with physical ones.\nNumerical application to the Helium isoelectronic series illustrates the\nmethod's viability and potential.",
        "positive": "Pair potentials and equation of state of solid parahydrogen to megabar\n  pressure: We compute by means of Quantum Monte Carlo simulations the equation of state\nof bulk solid {para}hydrogen extrapolated to zero temperature, up to a pressure\nof ~ 2 MBar. We compare the equation of state yielded by three different pair\npotentials, namely the Silvera-Goldman, Buck and one recently proposed by\nMoraldi, modified at short distances to include a repulsive core, missing in\nthe originally proposed potential. The Moraldi pair potential yields an\nequation of state in very good agreement with experiment at megabar pressures,\nowing to its softer core, and is at least as accurate as the SG or the Buck at\nsaturated vapour pressure. Estimates for the experimentally measurable kinetic\nenergy per molecule are provided for all pair potentials."
    },
    {
        "anchor": "State of Co and Mn in half-metallic ferromagnet Co$_2$MnSi explored by\n  magnetic circular dichroism in hard X-ray photoelectron emission and soft\n  X-ray absorption spectroscopies: The half-metallic Heusler compound Co$_2$MnSi is a very attractive material\nfor spintronic devices because it exhibits very high tunnelling\nmagnetoresistance ratios. This work reports on a spectroscopic investigation of\nthin Co$_2$MnSi films as they are used as electrodes in magnetic tunnel\njunctions. The investigated films exhibit a remanent in-plane magnetisation\nwith a magnetic moment of about 5~$\\mu_B$ when saturated, as expected. The low\ncoercive field of only 4~mT indicates soft magnetic behaviour. Magnetic\ndichroism in emission and absorption was measured at the Co and Mn $2p$ core\nlevels. The photoelectron spectra were excited by circularly polarised hard\nX-rays with an energy of of 6~keV and taken from the remanently magnetised\nfilm. The soft X-ray absorption spectra were taken in an induction field of\n4~T. Both methods yielded large dichroism effects. An analysis reveals the\nlocalised character of the electrons and magnetic moments attributed to the Mn\natoms, whereas the electrons related to the Co atoms contribute an itinerant\npart to the total magnetic moment.",
        "positive": "Electronic band structure change with structural transition of buckled\n  Au$_2$X monolayers induced by strain: This study investigates the strain-induced structural transitions of $\\eta\n\\leftrightarrow \\theta$ and the changes in electronic band structures of\nAu$_2$X (X=S, Se, Te, Si, Ge) and Au$_4$SSe. We focus on Au$_2$S monolayers,\nwhich can form multiple meta-stable monolayers theoretically, including\n$\\eta$-Au$_2$S, a buckled penta-monolayer composed of a square Au lattice and S\nadatoms. The $\\theta$-Au$_2$S is regarded as a distorted structure of\n$\\eta$-Au$_2$S. Based on density functional theory (DFT) calculations using a\ngeneralized gradient approximation, the conduction and the valence bands of\n$\\theta$-Au$_2$S intersect at the $\\Gamma$ point, leading to linear dispersion,\nwhereas $\\eta$-Au$_2$S has a band gap of 1.02 eV. The conduction band minimum\ndepends on the specific Au-Au bond distance, while the valence band maximum\ndepends on both Au-S and Au-Au interactions. The band gap undergoes significant\nchanges during the $\\eta \\leftrightarrow \\theta$ phase transition of Au$_2$S\ninduced by applying tensile or compressive in-plane biaxial strain to the\nlattice. Moreover, substituting S atoms with other elements alters the\nelectronic band structures, resulting in a variety of physical properties\nwithout disrupting the fundamental Au lattice network. Therefore, the family of\nAu$_2$X monolayers holds potential as materials for atomic scale network\ndevices."
    },
    {
        "anchor": "Photocurrents, inverse Faraday effect and photospin Hall effect in\n  Mn$_2$Au: Among antiferromagnetic materials, Mn$_2$Au is one of the most intensively\nstudied, and it serves as a very popular platform for testing various ideas\nrelated to antiferromagnetic magnetotransport and dynamics. Since recently,\nthis material has also attracted considerable interest in the context of\noptical properties and optically-driven antiferromagnetic switching. In this\nwork, we use first principles methods to explore the physics of charge\nphotocurrents, spin photocurrents and inverse Faraday effect in\nantiferromagnetic Mn$_2$Au. We predict the symmetry and magnitude of these\neffects, and speculate that they can be used for tracking the dynamics of\nstaggered moments during switching. Our calculations reveal the emergence of\nlarge photocurrents of spin in collinear Mn$_2$Au, whose properties can be\nunderstood as a result of a non-linear optical version of spin Hall effect $-$\nwhich we refer to as the $\\textit{photospin Hall effect}$ encoded into the\nrelation between the driving charge and resulting spin photocurrents. Moreover,\nwe suggest that even a very small canting in Mn$_2$Au can give rise to colossal\nspin photocurrents which are $\\textit{chiral}$ in flavor. We conclude that the\ncombination of staggered magnetization with the structural and electronic\nproperties of this material results in a unique blend of prominent\nphotocurrents, which makes Mn$_2$Au a unique platform for advanced\noptospintronics applications.",
        "positive": "Spontaneous skyrmionic lattice from anisotropic symmetric exchange in a\n  Ni-halide monolayer: Topological spin structures, such as magnetic skyrmions, hold great promises\nfor data storage applications, thanks to their inherent stability. In most\ncases, skyrmions are stabilized by magnetic fields in non-centrosymmetric\nsystems displaying the chiral Dzyaloshinskii-Moriya exchange interaction, while\nspontaneous skyrmion lattices have been reported in centrosymmetric itinerant\nmagnets with long-range interactions. Here, a spontaneous anti-biskyrmion\nlattice with unique topology and chirality is predicted in the monolayer of a\nsemiconducting and centrosymmetric metal halide, NiI$_2$. Our first-principles\nand Monte Carlo simulations reveal that the anisotropies of the short-range\nsymmetric exchange, when combined with magnetic frustration, can lead to an\nemergent chiral interaction that is responsible for the predicted topological\nspin structures. The proposed mechanism finds a prototypical manifestation in\ntwo-dimensional magnets, thus broadening the class of materials that can host\nspontaneous skyrmionic states."
    },
    {
        "anchor": "Highly-Oriented Atomically Thin Ambipolar MoSe$_2$ Grown by Molecular\n  Beam Epitaxy: Transition metal dichalcogenides (TMDCs), together with other two-dimensional\n(2D) materials have attracted great interest due to the unique optical and\nelectrical properties of atomically thin layers. In order to fulfill their\npotential, developing large-area growth and understanding the properties of\nTMDCs have become crucial. Here, we used molecular beam epitaxy (MBE) to grow\natomically thin MoSe$_2$ on GaAs(111)B. No intermediate compounds were detected\nat the interface of as-grown films. Careful optimization of the growth\ntemperature can result in the growth of highly aligned films with only two\npossible crystalline orientations due to broken inversion symmetry. As-grown\nfilms can be transferred onto insulating substrates allowing their optical and\nelectrical properties to be probed. By using polymer electrolyte gating, we\nhave achieved ambipolar transport in MBE-grown MoSe$_2$. The\ntemperature-dependent transport characteristics can be explained by the 2D\nvariable-range hopping (2D-VRH) model, indicating that the transport is\nstrongly limited by the disorder in the film.",
        "positive": "Ultrahigh Thermal Conductivity of Cubic Boron Arsenide with an\n  Unexpectedly Strong Temperature Dependence: Materials with high thermal conductivity are needed to conduct heat away from\nhot spots in power electronics and optoelectronic devices. Cubic boron arsenide\n(c-BAs) has a high thermal conductivity due to its special phonon dispersion\nrelation. Previous experimental studies of c-BAs report a room-temperature\nthermal conductivity between 1000 and 1300 watts per meter-kelvin. We\nsynthesized high purity c-BAs single crystals with room-temperature thermal\nconductivity of 1500 watts per meter-kelvin. We observed its thermal\nconductivity to be proportional to the inverse square of temperature between\n300 and 600 kelvin, a stronger dependence than predicted by state-of-the-art\ntheory."
    },
    {
        "anchor": "High coercivity induced by mechanical milling in cobalt ferrite powders: In this work we report a study of the magnetic behavior of ferrimagnetic\noxide CoFe2O4 treated by mechanical milling with different grinding balls. The\ncobalt ferrite nanoparticles were prepared using a simple hydrothermal method\nand annealed at 500oC. The non-milled sample presented coercivity of about 1.9\nkOe, saturation magnetization of 69.5 emu/g, and a remanence ratio of 0.42.\nAfter milling, two samples attained coercivity of 4.2 and 4.1 kOe, and\nsaturation magnetization of 67.0 and 71.4 emu/g respectively. The remanence\nratio MR/MS for these samples increase to 0.49 and 0.51, respectively. To\ninvestigate the influence of the microstructure on the magnetic behavior of\nthese samples, we used X-ray powder diffraction (XPD), transmission electron\nmicroscopy (TEM), and vibrating sample magnetometry (VSM). The XPD analysis by\nthe Williamson-Hall plot was used to estimate the average crystallite size and\nstrain induced by mechanical milling in the samples.",
        "positive": "Comment on Crystallite size dependent exchange bias in MgFe2O4 thin\n  films on Si (100), Journal of Applied Physics, volume 124, page 053901, 2018: K. Mallick and P. S. A. Kumar had reported exchange bias effect in Mg-ferrite\nthin films, deposited on Si substrate (with a buffer layer of MgO) using Pulsed\nLaser Deposition (PLD) technique. The authors had presented the temperature\ndependence exchange bias effect, field dependence exchange bias effect and\ntraining effect of a selected Magnesium ferrite thin film of thickness 132 nm.\nThese studies were followed by the film thickness dependence of exchange bias\neffect. However, the data presented for the 132 nm thick film shows mutually\ncontradicting values in each and every figures. Here, I point out these highly\nself-contradicting data in this comment."
    },
    {
        "anchor": "Pervasive liquid metal direct writing electronics with roller-ball pen: A roller-ball pen enabled direct writing electronics via room temperature\nliquid metal ink was proposed. With the rolling to print mechanism, the\nmetallic inks were smoothly written on flexible polymer substrate to form\nconductive tracks and electronic devices. The contact angle analyzer and\nscanning electron microscope were implemented to probe the inner property of\nthe obtained electronics. An ever high writing resolution with line width and\nthickness as 200{\\mu}m and 80{\\mu}m, respectively was realized. Further, with\nthe administration of external writing pressure, GaIn24.5 droplets embody\nincreasing wettability on polymer which demonstrates the pervasive adaptability\nof the roller-ball pen electronics.",
        "positive": "Native defect assisted enhanced response to CH4 near room temperature by\n  Al0.07Ga0.93N nanowires: Gas sensors at low operating temperature with high sensitivity are the demand\nfor the group III nitrides owing to their high chemical and thermal stability.\nThe CH4 sensing is realized for the Al0.07Ga0.93N nanowires (NWs) with an\nimproved response over the GaN NWs at a low operating temperature of 50\n{\\deg}C, for the first time. Al0.07Ga0.93N NWs were synthesized via ion beam\nmixing process using inert gas ion irradiation on the bilayer of Al/GaN NWs.\nThe sensing mechanism is explained with the help of native defects present in\nthe system. The number of shallow acceptors created by Ga vacancy (V_Ga) is\nfound to be higher in Al0.07Ga0.93N NWs than those in the as-grown GaN NWs. The\nrole of O antisite defect (ON) for the formation of shallow V_Ga is inferred\nfrom photoluminescence spectroscopic analysis. These native defects strongly\ninfluence the gas sensing behaviour resulting in the enhanced and low\ntemperature CH4 sensing."
    },
    {
        "anchor": "Local anodic oxidation on hydrogen-intercalated graphene layers: oxide\n  composition analysis and role of the silicon carbide substrate: We investigate nanoscale local anodic oxidation (LAO) on\nhydrogen-intercalated graphene grown by controlled sublimation of silicon\ncarbide (SiC). Scanning probe microscopy (SPM) was used as a lithographic and\ncharacterization tool in order to investigate the local properties of the\nnanofabricated structures. The anomalous thickness observed after the graphene\noxidation process is linked to the impact of LAO on the substrate. Micro-Raman\nspectroscopy was employed to demonstrate the presence of two oxidation regimes\ndepending on the applied bias. We show that partial and total etching of\nmonolayer graphene can be achieved by tuning the bias voltage during LAO.\nFinally, a complete compositional characterization was achieved by scanning\nelectron microscopy and energy dispersive spectroscopy (EDS).",
        "positive": "Temperature-Dependent Infrared Reflectivity Studies of Multiferroic\n  TbMnO_{3}: Evidence for Spin-Phonon Coupling: We have measured near normal incidence far infrared (FIR) reflectivity\nspectra of a single crystal of TbMnO3 from 10K to 300K in the spectral range of\n50 cm$^{-1}$ to 700 cm$^{-1}$. Fifteen transverse optic (TO) and longitudinal\noptic (LO) modes are identified in the imaginary part of the dielectric\nfunction $\\epsilon_2$($\\omega$) and energy loss function\nIm(-1/$\\epsilon$($\\omega$)), respectively. Some of the observed phonon modes\nshow anomalous softening below the magnetic transition temperature T$_N$ (~\n46K). We attribute this anomalous softening to the spin-phonon coupling caused\nby phonon modulation of the super-exchange integral between the Mn$^{3+}$\nspins. The effective charge of oxygen (Z$_O$) calculated using the measured\nLO-TO splitting increases below T$_N$."
    },
    {
        "anchor": "Ab initio prediction on ferrotoroidic olivine Li4MnFeCoNiP4O16: First-principles calculation predict that olivine Li4MnFeCoNiP4O16 has\nferrotoroidic characteristic and ferrimagnetic configuration with magnetic\nmoment of 1.56 \\muB per formula unit. The ferrotoroidicity of this material\nmakes it a potential candidate for magnetoelectric materials . Based on the\norbital-resolved density of states for the transtion-metal ions in\nLi4MnFeCoNiP4O16, the spin configuration for Mn2+,Fe3+,Co2+, and Ni2+ is\nt2g3eg2, t2g3eg2,t2g1t2g3eg1eg2, and t2g2t2g3eg1eg2, respectively. Density\nfunctional theory plus U (DFT+U) shows a indirect band gap of 1.25 eV in this\npredicted material, which is not simply related to the electronic conductivity\nin terms of being used as cathode material in rechargeable Li-ion batteries.",
        "positive": "Thickness dependences of photoelectric characteristics of silicon\n  backside contact solar cells: The thickness dependences of the photocurrent quantum yield and photoenergy\nparameters of silicon backside contact solar cells (BC SC) are investigated\ntheoretically and experimentally. The surface recombination rate on the\nirradiated surface was minimized by means of creating the layers of microporous\nsilicon. A method of finding the surface recombination rate and the diffusion\nlength of minority carriers from the thickness dependences of the photocurrent\nquantum yield under conditions of the strong absorption is proposed. The\nperformed studies allowed us to establish that the thinning of the BC SC\nsamples in the case of minimizing the surface recombination rate gives a\npossibility to achieve rather high efficiencies of photoconversion. It is also\nshown that the agreement between the experimental and theoretical spectral\ndependences of the photocurrent quantum yield can be reached only with regard\nfor the coefficient of light reflection from the backside surface."
    },
    {
        "anchor": "Stochastic Dynamics of Resistive Switching: Fluctuations Lead to Optimal\n  Particle Number: Resistive switching is one of the foremost candidates for building novel\ntypes of non-volatile random access memories. Any practical implementation of\nsuch a memory cell calls for a strong miniaturization, at which point\nfluctuations start playing a role that cannot be neglected. A detailed\nunderstanding of switching mechanisms and reliability is essential. For this\nreason, we formulate a particle model based on the stochastic motion of oxygen\nvacancies. It allows us to investigate fluctuations in the resistance states of\na switch with two active zones. The vacancies' dynamics is governed by a master\nequation. Upon the application of a voltage pulse, the vacancies travel\ncollectively through the switch. By deriving a generalized Burgers equation we\ncan interpret this collective motion as nonlinear traveling waves, and\nnumerically verify this result. Further, we define binary logical states by\nmeans of the underlying vacancy distributions, and establish a framework of\nwriting and reading such memory element with voltage pulses. Considerations\nabout the dis- criminability of these operations under fluctuations together\nwith the markedness of the resistive switching effect itself lead to the\nconclusion, that an intermediate vacancy number is optimal for performance.",
        "positive": "Topological characterization of antireflective and hydrophobic rough\n  surfaces: are random process theory and fractal modeling applicable?: The random process theory (RPT) has been widely applied to predict the joint\nprobability distribution functions (PDFs) of asperity heights and curvatures of\nrough surfaces. A check of the predictions of RPT against the actual statistics\nof numerically generated random fractal surfaces and of real rough surfaces has\nbeen only partially undertaken. The present experimental and numerical study\nprovides a deep critical comparison on this matter, providing some insight into\nthe capabilities and limitations in applying RPT and fractal modeling to\nantireflective and hydrophobic rough surfaces, two important types of textured\nsurfaces. A multi-resolution experimental campaign by using a confocal\nprofilometer with different lenses is carried out and a comprehensive software\nfor the statistical description of rough surfaces is developed. It is found\nthat the topology of the analyzed textured surfaces cannot be fully described\naccording to RPT and fractal modeling. The following complexities emerge: (i)\nthe presence of cut-offs or bi-fractality in the power-law power-spectral\ndensity (PSD) functions; (ii) a more pronounced shift of the PSD by changing\nresolution as compared to what expected from fractal modeling; (iii) inaccuracy\nof the RPT in describing the joint PDFs of asperity heights and curvatures of\ntextured surfaces; (iv) lack of resolution-invariance of joint PDFs of textured\nsurfaces in case of special surface treatments, not accounted by fractal\nmodeling."
    },
    {
        "anchor": "Unravelling the stability, electronic and physical properties in bulk\n  and (001)-surfacesof newlysynthesized Ti2ZnX (X=C, N)MAX phases: MAX phase family has been extended by the addition of late transition metals\nat the A-site with the expectation of diverse functional properties, such as\nmagnetism and catalysis. Here, we present our systematic density functional\ninvestigation on the phase stability and physical properties of newly\nsynthesized Ti2ZnX (X = C, N) phasesin comparison with conventional Ti2AlX (X =\nC, N).Due to smaller size of N as compared to C, the unit cell dimensionis\nreduced when C atoms are replaced by N atoms atthe X-site. The thermodynamic,\nmechanical and dynamical stabilities are validatedby estimating the formation\nenergies, elastic constants and phonon dispersions, respectively. The elastic\nproperties of Ti2ZnN are nearly isotropic while those of Ti2ZnC are completely\nanisotropic. To understand the thin-film characteristicsin Ti2ZnX, the surface\nproperties with (001)-terminated slabs are investigated. Both Ti2ZnX bulk and\n(001)-surfaces exhibit metal-like electronic structure. There is a strong\ncovalent bonding between Ti-X and Ti-Zn atoms.Additional states are generated\nat the Fermi level (EF) due to the unusual d-pstates hybridization between Ti\nand Zn atoms.The anisotropy in chemical bonding is confirmed by the cleavage\nenergy difference between Ti-X and Ti-Zn atoms. Here,Ti(X)-001 and Zn-001\nterminations are stable surfaces, however, in terms of chemical potentials,\nZn-001 termination is the most favorable.",
        "positive": "Evaluation of nonlocal approaches for modelling fracture near nonconvex\n  boundaries: Integral-type nonlocal damage models describe the fracture process zones by\nregular strain profiles insensitive to the size of finite elements, which is\nachieved by incorporating weighted spatial averages of certain state variables\ninto the stress-strain equations. However, there is no consensus yet how the\ninfluence of boundaries should be taken into account by the averaging\nprocedures. In the present study, nonlocal damage models with different\naveraging procedures are applied to the modelling of fracture in specimens with\nvarious boundary types. Firstly, the nonlocal models are calibrated by fitting\nload-displacement curves and dissipated energy profiles for direct tension to\nthe results of mesoscale analyses performed using a discrete model. These\nanalyses are set up so that the results are independent of boundaries. Then,\nthe models are applied to two-dimensional simulations of three-point bending\ntests with a sharp notch, a V-type notch, and a smooth boundary without a\nnotch. The performance of the nonlocal approaches in modelling of fracture near\nnonconvex boundaries is evaluated by comparison of load-displacement curves and\ndissipated energy profiles along the beam ligament with the results of\nmeso-scale simulations. As an alternative approach, elastoplasticity combined\nwith nonlocal or over-nonlocal damage is also included in the comparative\nstudy."
    },
    {
        "anchor": "Phase segregation on the nanoscale in Na2C60: Na2C60 is believed to be an electron-hole counterpart of the\nMott-Jahn--Teller insulator A4C60 salts. We present a study of infrared, ESR,\nNMR spectroscopy, X-ray diffraction, chemical composition and neutron\nscattering on this compound. Our spectroscopic results at room temperature can\nbe reconciled in a picture of segregated, separate regions of the size 3--10\nnm. We observe a significant insulating C60 phase and at least two more phases,\none of which we assign to metallic Na3C60. The separation disappears on heating\nby jump diffusion of the sodium ions, which we followed by neutron scattering.\nAbove ~460 K we see infrared spectroscopic evidence of a Jahn--Teller distorted\n(C60)2- anion.",
        "positive": "The SIESTA method for ab initio order-N materials simulation: We have developed and implemented a self-consistent density functional method\nusing standard norm-conserving pseudopotentials and a flexible, numerical LCAO\nbasis set, which includes multiple-zeta and polarization orbitals. Exchange and\ncorrelation are treated with the local spin density or generalized gradient\napproximations. The basis functions and the electron density are projected on a\nreal-space grid, in order to calculate the Hartree and exchange-correlation\npotentials and matrix elements, with a number of operations that scales\nlinearly with the size of the system. We use a modified energy functional,\nwhose minimization produces orthogonal wavefunctions and the same energy and\ndensity as the Kohn-Sham energy functional, without the need of an explicit\northogonalization. Additionally, using localized Wannier-like electron\nwavefunctions allows the computation time and memory, required to minimize the\nenergy, to also scale linearly with the size of the system. Forces and stresses\nare also calculated efficiently and accurately, thus allowing structural\nrelaxation and molecular dynamics simulations."
    },
    {
        "anchor": "Interplay between structure and magnetism in $Mo_{12} S_9 I_9$ nanowires: We investigate the equilibrium geometry and electronic structure of\nMo$_{12}$S$_{9}$I$_{9}$ nanowires using ab initio Density Functional\ncalculations. The skeleton of these unusually stable nanowires consists of\nrigid, functionalized Mo octahedra, connected by flexible, bi-stable sulphur\nbridges. This structural flexibility translates into a capability to stretch up\nto approximate 20% at almost no energy cost. The nanowires change from\nconductors to narrow-gap magnetic semiconductors in one of their structural\nisomers.",
        "positive": "Comment on Synthesis of rhenium nitride crystal with MoS2 structure: Kawamura et. al. recently published an article about the synthesis of rhenium\nnitride with MoS2-type structure [APL 100, 251910(2012)]. We disagree with the\ncomposition proposed by Kawamura. The compound synthesized by Kawamura is ReN3,\nor a compound of similar composition. What Kawamura did is to find the Re\natomic positions of a compound where the nitrogen concentration remains\nunknown. This paper was rejected form APL. The reviewer comments (and our\nreply) are included here."
    },
    {
        "anchor": "Grand Canonical Monte Carlo Simulation of Hydrogen Adsorption in\n  Different Carbon Nano Structures: Grand Canonical Monte Carlo (GCMC) simulations are performed to study\nhydrogen physisorption in different nano carbon porous materials made up of\ndifferent substructures including carbon nanotubes (CNT), graphene sheets and\nC60. Hydrogen weight percentage (wt%) at different temperatures with pressure\nranging from 1 to 20MPa are predicted. Fugacity and quantum effects on hydrogen\nadsorption are investigated. Different structural dimensions including the\nsizes of the substructures and spacing between the substructures are used to\nstudy the geometrical effects on hydrogen storage capacity in carbon materials.\nThe calculated results generally agree well with available data from other\ncalculations. It is concluded that CNT arrays, graphite nanofibers (GNF) and\nC60 intercalated graphite (CIG) are not promising to reach the DOE 6.5 wt%\ntarget at room temperature. It is also found that the quantum effect is\nsignificant in low temperature hydrogen adsorption and different treatments to\naccount for the quantum effect also influence the predicted wt% differently.",
        "positive": "Pentagonal nanowires: a first-principles study of atomic and electronic\n  structure: We performed an extensive first-principles study of nanowires in various\npentagonal structures by using pseudopotential plane wave method within the\ndensity functional theory. Our results show that nanowires of different types\nof elements, such as alkali, simple, transition and noble metals and inert gas\natoms, have a stable structure made from staggered pentagons with a linear\nchain perpendicular to the planes of the pentagons and passing through their\ncenters. This structure exhibits bond angles close to those in the icosahedral\nstructure. However, silicon is found to be energetically more favorable in the\neclipsed pentagonal structure. These quasi one dimensional pentagonal nanowires\nhave higher cohesive energies than many other one dimensional structures and\nhence may be realized experimentally. The effect of magnetic state are examined\nby spin-polarized calculations. The origin of the stability are discussed by\nexamining optimized structural parameters, charge density and electronic band\nstructure, and by using analysis based on the empirical Lennard-Jones type\ninteraction. Electronic band structure of pentagonal wires of different\nelements are discussed and their effects on quantum ballistic conductance are\nmentioned. It is found that the pentagonal wire of silicon exhibits metallic\nband structure."
    },
    {
        "anchor": "A phase field electro-chemo-mechanical formulation for predicting void\n  evolution at the Li-electrolyte interface in all-solid-state batteries: We present a mechanistic theory for predicting void evolution in the Li metal\nelectrode during the charge and discharge of all-solid-state battery cells. A\nphase field formulation is developed to model vacancy annihilation and\nnucleation, and to enable the tracking of the void-Li metal interface. This is\ncoupled with a viscoplastic description of Li deformation, to capture creep\neffects, and a mass transfer formulation accounting for substitutional (bulk\nand surface) Li diffusion and current-driven flux. Moreover, we incorporate the\ninteraction between the electrode and the solid electrolyte, resolving the\ncoupled electro-chemical-mechanical problem in both domains. This enables\npredicting the electrolyte current distribution and thus the emergence of local\ncurrent 'hot spots', which act as precursors for dendrite formation and cell\ndeath. The theoretical framework is numerically implemented, and single and\nmultiple void case studies are carried out to predict the evolution of voids\nand current hot spots as a function of the applied pressure, material\nproperties and charge (magnitude and cycle history). For both plating and\nstripping, insight is gained into the interplay between bulk diffusion, Li\ndissolution and deposition, creep, and the nucleation and annihilation of\nvacancies. The model is shown to capture the main experimental observations,\nincluding not only key features of electrolyte current and void morphology but\nalso the sensitivity to the applied current, the role of pressure in increasing\nthe electrode-electrolyte contact area, and the dominance of creep over vacancy\ndiffusion.",
        "positive": "Biredox ionic liquids with solid-like redox density in the liquid state\n  for high-energy supercapacitors: Kinetics of electrochemical reactions are several orders of magnitude slower\nin solids than in liquids as a result of the much lower ion diffusivity. Yet,\nthe solid state maximizes the density of redox species, which is at least two\norders of magnitude lower in liquids because of solubility limitations. With\nregard to electrochemical energy storage devices, this leads to high-energy\nbatteries with limited power and high-power supercapacitors with a well-known\nenergy deficiency. For such devices the ideal system should endow the liquid\nstate with a density of redox species close to the solid state. Here we report\nan approach based on biredox ionic liquids to achieve bulk-like redox density\nat liquid like fast kinetics. The cation and anion of these biredox ILs bear\nmoieties that undergo very fast reversible redox reactions. As a first\ndemonstration of their potential for high-capacity / high-rate charge storage,\nwe used them in redox supercapacitors. These ionic liquids are able to decouple\ncharge storage from ion accessible electrode surface, by storing significant\ncharge in the pores of the electrodes, to minimize self-discharge and leakage\ncurrent as a result of retaining the redox species in the pores, and to raise\nworking voltage due to their wide electrochemical window."
    },
    {
        "anchor": "Effect of oxygen adsorption and oxidation on the strain state of Pd\n  nanocrystals: X-ray powder diffraction using a synchrotron light source reveals significant\nmodifications to both morphology and strain state in Palladium nanocubes after\noxidation. Short-range strain measured by the static component of the\nDebye-Waller coefficient is observed to be higher in the oxidized\nnanoparticles; while long-range strain related to the line broadening of the\ndiffraction peaks is seen to decrease. Using multiscale modelling with\nclassical molecular dynamics and density functional theory, we connect the\ndecrease in long-range strain to the increased truncation of the oxidized\nnanocubes, while the higher short-range strain is shown to be due to surface\nsoftening from oxygen adsorption. Different surface disorder on different\ncrystallographic facets lead to opposing trends for oxygen activation on the\ndifferent exposed surfaces of the truncated nanoparticles.",
        "positive": "Perspective on first-principles studies of 2D materials: The successful exfoliation of graphene from graphite has brought significant\nattention to predicting new two-dimensional (2D) materials that can be realized\nexperimentally. As a consequence, first-principles studies of novel 2D\nmaterials become a routine, with thousands of papers published every year. What\nmakes these studies interesting is that they predict new materials which have\nnot been realized yet but should be a panacea for topological insulators,\nnext-generation battery materials, novel solar cell materials, etc. There is no\ndoubt that some of the proposed materials can provide a specific solution and\ntheir properties/performance can be confirmed experimentally, at the same time\nthere are many false predictions because of the computational errors or the\nLego-land approach to study 2D materials. To reduce the gap between theoretical\nand experimental works, we perform a systematic review of computational and\nLego-land factors that should be minimized in future theoretical works."
    },
    {
        "anchor": "Influence of (N,H)-terminated surfaces on stability, hyperfine\n  structure, and zero-field splitting of NV centers in diamond: We present a density functional theory analysis of the negatively charged\nnitrogen-vacancy (NV$^-$) defect complex in diamond located in the vicinity of\n(111)- or (100)-oriented surfaces with mixed (N,H)-terminations. We assess the\nstability and electronic properties of the NV$^-$ center and study their\ndependence on the H:N ratio of the surface termination. The formation energy,\nthe electronic density of states, the hyperfine structure and zero-field\nsplitting parameters of an NV$^-$ center are analyzed as function of its\ndistance and orientation to the surface. We find stable NV$^-$ centers with\nbulk-like properties at distances of at least $\\sim8$ Angstroem from the\nsurface provided that the surface termination consists of at least 25\\%\nsubstitutional nitrogen atoms. Our results indicate that axial NV centers near\na flat 100\\% N-terminated (111) surface are the optimal choice for NV-based\nquantum sensing applications as they are the least influenced by the proximity\nof the surface.",
        "positive": "Effect of line defects on the electrical transport properties of\n  monolayer MoS$_{2}$ sheet: We present a computational study on the impact of line defects on the\nelectronic properties of monolayer MoS2. Four different kinds of line defects\nwith Mo and S as the bridging atoms, consistent with recent theoretical and\nexperimental observations are considered herein. We employ the density\nfunctional tight-binding (DFTB) method with a Slater-Koster type DFTB-CP2K\nbasis set for evaluating the material properties of perfect and the various\ndefective MoS2 sheets. The transmission spectra is computed with a\nDFTB-Non-Equilibrium Greens Function (NEGF) formalism. We also perform a\ndetailed analysis of the carrier transmission pathways under a small bias and\ninvestigate the phase shifts in the transmission eigenstates of the defective\nMoS2 sheets. Our simulations show a 2-4 folds decrease in carrier conductance\nof MoS2 sheets in the presence of line defects as compared to that for the\nperfect sheet."
    },
    {
        "anchor": "Strain effects on phonon transport in antimonene from a first-principles\n  study: Strain engineering is a very effective method to continuously tune the\nelectronic, topological, optical and thermoelectric properties of materials. In\nthis work, strain-dependent phonon transport of recently-fabricated antimonene\n(Sb monolayer) under biaxial strain is investigated from a combination of\nfirst-principles calculations and the linearized phonon Boltzmann equation. It\nis found that the ZA dispersion of antimonene with strain less than -1\\% gives\nimaginary frequencies, which suggests that compressive strain can induce\nstructural instability. Experimentally, it is possible to enhance structural\nstability by tensile strain. Calculated results show that lattice thermal\nconductivity increases with strain changing from -1\\% to 6\\%, and lattice\nthermal conductivity at 6\\% strain is 5.6 times larger than that at -1\\% strain\nat room temperature. It is interesting that lattice thermal conductivity is in\ninverse proportion to buckling parameter $h$ in considered strain range. Such a\nstrain dependence of lattice thermal conductivity is attributed to enhanced\nphonon lifetimes caused by increased strain, while group velocities have a\ndecreased effect on lattice thermal conductivity with increasing strain. It is\nfound that acoustic branches dominate the lattice thermal conductivity over the\nfull strain range. The cumulative room-temperature lattice thermal conductivity\nat -1\\% strain converges to maximum with phonon mean free path (MFP) at 50 nm,\nwhile one at 6\\% strain becomes as large as 44 $\\mathrm{\\mu m}$, which suggests\nthat strain can give rise to very strong size effects on lattice thermal\nconductivity in antimonene. These results may provide guidance on fabrication\ntechniques of antimonene, and offer perspectives on tuning lattice thermal\nconductivity by size and strain for applications of thermal management and\nthermoelectricity.",
        "positive": "Surface phonons limit heat conduction in thin films: Understanding microscopic heat conduction in thin films is important for\nnano/micro heat transfer and thermal management for advanced electronics. As\nthe thickness of thin films is comparable to or shorter than a phonon\nwavelength, phonon dispersion relations and transport properties are\nsignificantly modulated, which should be taken into account for heat conduction\nin thin films. Although phonon confinement and depletion effects have been\nconsidered, it should be emphasized that surface-localized phonons (surface\nphonons) arise whose influence on heat conduction may not be negligible due to\nthe high surface-to-volume ratio. However, the role of surface phonons in heat\nconduction has received little attention thus far. In the present work, we\nperformed anharmonic lattice dynamics calculations to investigate the thickness\nand temperature dependence of in-plane thermal conductivity of silicon thin\nfilms with sub-10-nm thickness in terms of surface phonons. Through systematic\nanalysis of the influences of surface phonons, we found that anharmonic\ncoupling between surface and internal phonons localized in thin films\nsignificantly suppresses overall in-plane heat conduction in thin films. We\nalso discovered that specific low-frequency surface phonons significantly\ncontribute to surface--internal phonon scattering and heat conduction\nsuppression. Our findings are beneficial for the thermal management of\nelectronics and phononic devices and may lead to surface phonon engineering for\nthermal conductivity control."
    },
    {
        "anchor": "Effect of symmetry on the electronic DOS, charge fluctuations and\n  electron-phonon coupling in carbon chains: A theoretical model is provided to address the parameters influencing the\nelectronic properties of kink-structured carbon chain at 0K. It is studied by\nthe principle of DFT and solving the numerical 1D time-independent\nSchr\\\"odinger equation of electron and phonon simultaneously. Two different\nlengths of branches A and B, are occupied alternatively to generate the\nasymmetric carbon chain. The ratio of the asymmetric branch length,RAB=A/B,\nplays an important role in the electronic density of states DOS around Fermi\nlevel Ef . The highest DOS(Ef) occurs if the RAB equals to 2 and while the\nFermi level coincides with the Von-Hove singularity at RAB=3. The location of\nthe singularity point relative to the Ef is controllable via branch length\ninterestingly. By comparison with the symmetric case, tuning the branch length\nasymmetrically shows a stronger impact to shift the Ef to the singularity\npoint. The numerical solution of the 1D time independent Schrodinger equation\nof phonon indicates that the kink reinforces the charge fluctuations but the\nfluctuations are minimized when the RAB goes up. Based on the simulation\nresults, the electron phonon coupling of the carbon nanowire decreases with\nchain length. In comparison to the symmetric structure, the electron phonon\ncoupling of the asymmetric carbon chain is higher. The maximum electron phonon\ncoupling of the asymmetric carbon chain takes place at RAB=2 . However, the\nweakening of the electron phonon coupling is observed owing to ultrahigh\nconcentration of kinks. The reduction of the electron phonon coupling of the\ncarbon chain is occurred under pressure.",
        "positive": "Etching-dependent reproducible memory switching in vertical SiO2\n  structures: Vertical structures of SiO$_{2}$ sandwiched between a top tungsten electrode\nand conducting non-metal substrate were fabricated by dry and wet etching\nmethods. Both structures exhibit similar voltage-controlled memory behaviors,\nin which short voltage pulses (1 $\\mu$s) can switch the devices between high-\nand low-impedance states. Through the comparison of current-voltage\ncharacteristics in structures made by different methods, filamentary conduction\nat the etched oxide edges is most consistent with the results, providing\ninsights into similar behaviors in metal/SiO/metal systems. High ON/OFF ratios\nof over 10$^{4}$ were demonstrated."
    },
    {
        "anchor": "Unravelling the role of vacancies in lead halide perovskite through\n  electrical switching of photoluminescence: Methylammonium lead triiodide perovskite (MAPbI3) semiconductor displays\noutstanding photovoltaic and light emitting properties. We address the unique\nbehavior in which a bias voltage can be used to switch on and off the\nluminescence of a planar film with lateral symmetric electrodes. Instead of a\nhomogeneous suppression of emission, as in other organic semiconductor films,\nin MAPbI3 films a dark region advances from the positive electrode at a slow\nvelocity of order of 1 um s-1. Here we explain the existence of the sharp front\nin terms of the drift of ionic vacancies that drastically reduce the radiative\nrecombination rate in the film. Based on a dynamic transport model we show that\nthe square reciprocal of the electrical current is linear with time in\nagreement with the experimental observations. This insight leads to a direct\ndetermination of the diffusion coefficient of iodine vacancies D = 6 10-9 cm2\ns-1 and provides detailed information and control on the effect of ionic\nconduction over the electrooptical properties of hybrid perovskite materials.",
        "positive": "Phonon coherences reveal the polaronic character of excitons in\n  two-dimensional lead-halide perovskites: Hybrid organic-inorganic semiconductors feature complex lattice dynamics due\nto the ionic character of the crystal and the softness arising from\nnon-covalent bonds between molecular moieties and the inorganic network. Here\nwe establish that such dynamic structural complexity in a prototypical\ntwo-dimensional lead iodide perovskite gives rise to the coexistence of diverse\nexcitonic resonances, each with a distinct degree of polaronic character. By\nmeans of high-resolution resonant impulsive stimulated Raman spectroscopy, we\nidentify vibrational wavepacket dynamics that evolve along different\nconfigurational coordinates for distinct excitons and photocarriers. Employing\ndensity functional theory calculations, we assign the observed coherent\nvibrational modes to various low-frequency ($\\lesssim 50$\\,cm$^{-1}$) optical\nphonons involving motion in the lead-iodide layers. We thus conclude that\ndifferent excitons induce specific lattice reorganizations, which are\nsignatures of polaronic binding. This insight on the energetic/configurational\nlandscape involving globally neutral primary photoexcitations may be relevant\nto a broader class of emerging hybrid semiconductor materials."
    },
    {
        "anchor": "Design of a multifunctional polar metal via first-principles\n  high-throughput structure screening: Intrinsic polar metals are rare, especially in oxides, because free electrons\nscreen electric fields in a metal and eliminate the internal dipoles that are\nneeded to break inversion symmetry. Here we use first-principles\nhigh-throughput structure screening to predict a new polar metal in bulk and\nthin film forms. After screening more than 1000 different crystal structures,\nwe find that ordered BiPbTi2O6 can crystallize in three polar and metallic\nstructures, which can be transformed between via pressure or strain. In a\nheterostructure of layered BiPbTi2O6 and PbTiO3, multiple states with different\nrelative orientations of BiPbTi2O6 polar displacements, and PbTiO3\npolarization, can be stabilized. At room temperature, the interfacial coupling\nenables electric fields to first switch PbTiO3 polarization and subsequently\ndrive 180{\\deg} change of BiPbTi2O6 polar displacements. At low temperatures,\nthe heterostructure provides a tunable tunnelling barrier and might be used in\nmulti-state memory devices.",
        "positive": "Influence of static correlation on the magnon dynamics of an itinerant\n  ferromagnet with competing exchange interactions -- a first principles study\n  of MnBi: We present first principles calculations of the dynamic susceptibility in\nstrained and doped ferromagnetic MnBi using time-dependent density functional\ntheory. In spite of being a metal, MnBi exhibits signatures of strong\ncorrelation and a proper description in the framework of density functional\ntheory requires Hubbard corrections to the Mn $d$-orbitals. To permit\ncalculations of the dynamic susceptibility with Hubbard corrections applied to\nthe ground state electronic structure, we use a consistent rescaling of the\nexchange-correlation kernel maintaining the delicate balance between the magnon\ndispersion and the Stoner continuum. We find excellent agreement with the\nexperimentally observed magnon dispersion for pristine MnBi and show that the\nmaterial undergoes a phase transition to helical order under application of\neither doping or strain. The presented methodology paves the way for future\nLR-TDDFT studies of magnetic phase transitions, also for the wide range of\nmaterials with pronounced static correlation effects that are not accounted for\nat the LDA level."
    },
    {
        "anchor": "Impact of impurities on the topological boundaries and edge state\n  localization in a staggered chain of atoms: SSH model and its topoelectrical\n  circuit realization: We study the Su-Schrieffer-Hegger model, perhaps the simplest realization of\na topological insulator, in the presence of an embedded impurity superlattice.\nWe consider the impact of the said impurity by changing the hopping amplitudes\nbetween them and their nearest neighbors in the topological boundaries and the\nedge state localization in the chain of atoms. Within a tight-binding approach\nand through a topolectrical circuit simulation, we consider three different\nimpurity-hopping amplitudes. We found a relaxation of the condition between\nhopping parameters for the topologically trivial and non-trivial phase boundary\nand a more profound edge state localization given by the impurity position\nwithin the supercell.",
        "positive": "Optically- and thermally-driven huge lattice orbital and spin angular\n  momenta from spinning fullerenes: Lattice vibration in solids may carry angular momentum. But unlike the\nintrinsic spin of electrons, the lattice vibration is rarely rotational. To\ninduce angular momentum, one needs to find a material that can accommodate a\ntwisted normal mode, two orthogonal modes or excitation of magnons. If\nexcitation is too strong, one may exceed the Lindemann limit, so the material\nmelts. Therefore these methods are not ideal. Here, we theoretically propose a\nnew route to phonon angular momentum in a molecular crystal $\\rm C_{60}$. We\nfind that a single laser pulse is able to inject a significant amount of\nangular momentum to $\\rm C_{60}$, and the momentum transfer is\nhelicity-dependent. Changing from right-circularly polarized light to\nleft-circularly polarized light switches the direction of phonon angular\nmomentum. On the ultrafast time scale, the orbital angular momentum change\nclosely resembles the displacive excitation of coherent phonons, with a\ncosine-function dependence on time, different from the spin counterpart. Atomic\ndisplacements, even under strong laser excitation, remain far below the\nLindemann criterion. Under thermal excitation, spinning $\\rm C_{60}$ even at\nroom temperature generates a huge angular momentum close to several hundred\n$\\hbar$. Our finding opens the door to a large group of fullerenes, from $\\rm\nC_{60}$, C$_{70}$ to their endohedral derivatives, where angular momentum can\nbe generated through light or temperature. This paves the way to the phononic\ncontrol electronic spin and harvesting thermal energy through phonon angular\nmomentum."
    },
    {
        "anchor": "Direct Visualization of Trimerized States in 1T'-TaTe$_{2}$: Transition-metal dichalcogenides containing tellurium anions show remarkable\ncharge-lattice modulated structures and prominent interlayer character. Using\ncryogenic scanning transmission electron microscopy (STEM), we map the\natomic-scale structures of the high temperature (HT) and low temperature (LT)\nmodulated phases in 1T'-TaTe$_{2}$. At HT, we directly show in-plane metal\ndistortions which form trimerized clusters and staggered, three-layer stacking.\nIn the LT phase at 93 K, we visualize an additional trimerization of Ta sites\nand subtle distortions of Te sites by extracting structural information from\ncontrast modulations in plan-view STEM data. Coupled with density functional\ntheory calculations and image simulations, this approach opens the door for\natomic-scale visualizations of low temperature phase transitions and complex\ndisplacements in a variety of layered systems.",
        "positive": "Electron paramagnetic resonance of alkali metal atoms and dimers on\n  ultrathin MgO: Electron paramagnetic resonance (EPR) can provide unique insight into the\nchemical structure and magnetic properties of dopants in oxide and\nsemiconducting materials that are of interest for applications in electronics,\ncatalysis, and quantum sensing. Here, we demonstrate that EPR in combination\nwith scanning tunneling microscopy (STM) allows for probing the bonding and\ncharge state of alkali metal atoms on an ultrathin magnesium oxide layer on a\nAg substrate. We observe a magnetic moment of $1\\mu_\\mathrm{B}$ for Li$_2$,\nLiNa, and Na$_2$ dimers corresponding to spin radicals with a charge state of\n$+1e$. Single alkali atoms have the same charge state and no magnetic moment.\nThe ionization of the adsorbates is attributed to charge transfer through the\noxide to the metal substrate. Our work highlights the potential of EPR-STM to\nprovide insight into dopant atoms that are relevant for the control of the\nelectrical properties of surfaces and nanodevices."
    },
    {
        "anchor": "Structural and hyperfine characterization of \u03c3-phase Fe-Mo alloys: A series of nine samples of \\sigma-Fe_{100-x}Mo_x with 44<x<57 were\nsynthesized by a sintering method. The samples were investigated experimentally\nand theoretically. Using X-ray diffraction techniques structural parameters\nsuch as lattice constants, atomic positions within the unit cell and\npopulations of atoms over five different sublattices were determined. An\ninformation on charge-densities and electric field gradients at particular\nlattice sites was obtained by application of the Korringa-Kohn-Rostoker (KKR)\nmethod for electronic structure calculations. Hyperfine quantities calculated\nwith KKR were successfully applied to analyze Mossbauer spectra measured at\nroom temperature.",
        "positive": "Electronic redistribution around oxygen atoms in silicate melts by ab\n  initio molecular dynamics simulation: The structure around oxygen atoms of four silicate liquids (silica, rhyolite,\na model basalt and enstatite) is evaluated by ab initio molecular dynamics\nsimulation. Thanks to the use of maximally localized Wannier orbitals to\nrepresent the electronic ground state of the simulated system, one is able to\nquantify the redistribution of electronic density around oxygen atoms as a\nfunction of the cationic environment and melt composition. It is shown that the\nstructure of the melt in the immediate vicinity of the oxygen atoms modulates\nthe distribution of the Wannier orbitals associated with oxygen atoms. In\nparticular the evaluation of the distances between the oxygen-core and the\norbital Wannier centers and their evolution with the nature of the cation\nindicates that the Al-O bond in silicate melts is certainly less covalent than\nthe Si-O bond while for the series Mg-O, Ca-O, Na-O and K-O the covalent\ncharacter of the M-O bond diminishes rapidly to the benefit of the ionic\ncharacter. Furthermore it is found that the distribution of the oxygen dipole\nmoment coming from the electronic polarization is only weakly dependent on the\nmelt composition, a finding which could explain why some empirical force fields\ncan exhibit a high degree of transferability with melt composition."
    },
    {
        "anchor": "A Novel Nanoporous Graphite Based on Graphynes: First Principles\n  Structure and Carbon Dioxide Preferential Physisorption: Ubiquitous graphene is a stricly 2D material representing an ideal adsorbing\nplatform due to its large specific surface area as well as its mechanical\nstrength and resistance to both thermal and chemical stresses. However,\ngraphene as a bulk material has the tendency to form irreversible agglomerates\nleading to 3D graphitic structures with a significant decrease of the area\navailable for adsorption and no room for gas intercalation. In this paper a\nnovel nanoporous graphite formed by graphtriyne sheets is introduced: its 3D\nstructure is theoretically assessed by means of electronic structure and\nmolecular dynamics computations within the DFT level of theory. It is found\nthat the novel layered carbon allotrope is almost as compact as pristine\ngraphite but the inherent porosity of the 2D graphyne sheets and its relative\nstacking leads to nanochannels that cross the material and whose sub-nanometer\nsize could allow the diffusion and storage of gas species. A molecular\nprototype of the nanochannel is used to accurately determine first principles\nadsorption energies and enthalpies for CO2, N2, H2O and H2 within the pores.\nThe proposed porous graphite presents no significant barrier for gas diffusion\nand it shows a high propensity for CO2 physisorption with respect to the other\nrelevant components in both pre- and post-combustion gas streams.",
        "positive": "Time-Resolved XUV absorption spectroscopy and magnetic circular\n  dichroism at the Ni $M_{2,3}$-edges: Ultrashort optical pulses can trigger a variety of non-equilibrium processes\nin magnetic thin films affecting electrons and spins on femtosecond timescales.\nIn order to probe the charge and magnetic degrees of freedom simultaneously, we\ndeveloped an x-ray streaking technique that has the advantage of providing a\njitter-free picture of absorption cross section changes. In this paper, we\npresent an experiment based on this approach which we performed using five\nphoton probing energies at the Ni $M_{2,3}$-edges. This allowed us to retrieve\nthe absorption and magnetic circular dichroism time traces, yielding detailed\ninformation on transient modifications of electron and spin populations close\nto the Fermi level. Our findings suggest that the observed charge and magnetic\ndynamics both depend on the XUV probing wavelength, and can be described, at\nleast qualitatively, by assuming ultrafast energy shifts of the electronic and\nmagnetic elemental absorption resonances, as reported in recent work. However,\nour analysis also hints at more complex changes, highlighting the need for\nfurther experimental and theoretical analysis in order to gain a thorough\nunderstanding of the interplay of electronic and spin degrees of freedom in\noptically excited magnetic thin films."
    },
    {
        "anchor": "Band-Engineered LaFeO$_{3}$-LaNiO$_{3}$ Thin Film Interfaces for\n  Electrocatalysis of Water: Transition metal oxides have generated significant interest for their\npotential as catalysts for the oxygen evolution reaction (OER) in alkaline\nenvironments. Iron and nickel-based perovskite oxides have proven particularly\npromising, with catalytic over-potentials rivaling precious metal catalysts\nwhen the alignment of the valence band relative to the OER reaction potential\nis tuned through substitutional doping or alloying. Here we report that\nengineering of band alignment in LaFeO$_{3}$/LaNiO$_{3}$ (LFO/LNO)\nheterostructures via interfacial doping yields greatly enhanced catalytic\nperformance. Using density functional theory modeling, we predict a 0.2 eV\nvalence band offset (VBO) between metallic LNO and semiconducting LFO that\nsignificantly lowers the barrier for hole transport through LFO compared to the\nintrinsic material and make LFO a p-type semiconductor. Experimental band\nalignment measurements using in situ X-ray photoelectron spectroscopy of\nepitaxial LFO/LNO heterostructures agree quite well with these predictions,\nproducing a measured VBO of 0.3(1) eV. OER catalytic measurements on the same\nsamples in alkaline solution show an increase in catalytic current density by a\nfactor of ~275 compared to LFO grown on n-type Nb-doped SrTiO$_{3}$. These\nresults demonstrate the power of tuning band alignments through interfacial\nband engineering for improved catalytic",
        "positive": "Universal Displacements in Inextensible Fiber-Reinforced Linear Elastic\n  Solids: For a given class of materials, universal displacements are those\ndisplacements that can be maintained for any member of the class by applying\nonly boundary tractions. In this paper we study universal displacements in\ncompressible anisotropic linear elastic solids reinforced by a family of\ninextensible fibers. For each symmetry class and for a uniform distribution of\nstraight fibers respecting the corresponding symmetry we characterize the\nrespective universal displacements. A goal of this paper is to investigate how\nan internal constraint affects the set of universal displacements. We have\nobserved that other than the triclinic and cubic solids in the other five\nclasses (a fiber-reinforced solid with straight fibers cannot be isotropic) the\npresence of inextensible fibers enlarges the set of universal displacements."
    },
    {
        "anchor": "Generation of ground state structures and electronic properties of\n  ternary Al$_x$Ti$_y$Ni$_z$ clusters (x+y+z=6) with a two-stage DFT global\n  search approach: The structural and electronic properties of ternary AlxTiyNiz clusters, where\nx, y, and z are integers and x + y + z = 6 are investigated. Both SVWN and\nB3LYP exchange-correlation functionals are employed in a two-stage density\nfunctional theory (DFT) calculations to generate these clusters. In the first\nstage, a minimum energy cluster structure is generated by an unbiased global\nsearch algorithm coupled with a DFT code using a light exchange-correlation\nfunctional and small basis sets. In the second stage, the obtained cluster\nstructure is further optimized by another round of global minimization search\ncoupled with a DFT calculator using a heavier exchange-correlation functional\nand more costly basis set. Electronic properties of the structures are\nillustrated in the form of a ternary diagram. Our DFT calculations find that\nthe stability of the clusters increases with the increment in the number of\nconstituent nickel atoms. These results provide a new insight to the structure,\nstability, chemical order and electronic properties for the ternary alloy\nnanoclusters.",
        "positive": "Origin of ferroelectric-like hysteresis loop of CaCu3Ti4O12 ceramic\n  studied by impedance and micro-Raman spectroscopy: Ferroelectric-like hysteresis loops of CaCu3Ti4O12 (CCTO) ceramic have been\nobserved. We found that this unusual feature does not arise from the\ndisplacement of the Ti ions in the TiO6 octahedron, but apparently comes from\nthe charges at the grain boundaries which consist of a CuO layer. The\nrelaxation time of 2.9 milliseconds by the charges from the grain boundary,\nnearly corresponding to the inverse P - V sampling frequency of 1kHz, has been\nfound in the impedance spectrum. According to the micro-Raman mapping, the CuO\nlayer is found in the grain boundary and is perfectly distinguished from the\nCCTO grain."
    },
    {
        "anchor": "Optical transitions in hybrid perovskite solar cells: Ellipsometry,\n  density functional theory, and quantum efficiency analyses for CH3NH3PbI3: We report artifact-free CH3NH3PbI3 optical constants extracted from\nultra-smooth perovskite layers without air exposure and assign all the optical\ntransitions in the visible/ultraviolet region unambiguously based on density\nfunctional theory (DFT) analysis that assumes a simple pseudo-cubic crystal\nstructure. From the self-consistent spectroscopic ellipsometry analysis of the\nultra-smooth CH3NH3PbI3 layers, we find that the absorption coefficients of\nCH3NH3PbI3 (alpha = 3.8 x 10^4 cm-1 at 2.0 eV) are comparable to those of\nCuInGaSe2 and CdTe, and high alpha values reported in earlier studies are\noverestimated seriously by extensive surface roughness of CH3NH3PbI3 layers.\nThe polarization-dependent DFT calculations show that CH3NH3+ interacts\nstrongly with the PbI3- cage, modifying the CH3NH3PbI3 dielectric function in\nthe visible region rather significantly. When the effect of CH3NH3+ on the\noptical transition is eliminated in the DFT calculation, CH3NH3PbI3 dielectric\nfunction deduced from DFT shows excellent agreement with the experimental\nresult. As a result, distinct optical transitions observed at E0 (Eg) = 1.61\neV, E1 = 2.53 eV, and E2 = 3.24 eV in CH3NH3PbI3 are attributed to the direct\nsemiconductor-type transitions at the R, M, and X points in the pseudo-cubic\nBrillouin zone, respectively. We further perform the quantum efficiency (QE)\nanalysis for a standard hybrid-perovskite solar cell incorporating a mesoporous\nTiO2 layer and demonstrate that the QE spectrum can be reproduced almost\nperfectly when the revised CH3NH3PbI3 optical constants are employed.\nDepth-resolved QE simulations confirm that Jsc is limited by the material's\nlonger wavelength response and indicate the importance of optical confinement\nand long carrier diffusion lengths in hybrid perovskite solar cells.",
        "positive": "High Entropy Alloy Nanoparticles Decorated, p-type 2D-Molybdenum\n  Disulphide (MoS2) and Gold Schottky Junction Enhanced Hydrogen Sensing: Molybdenum Disulphide (MoS2) is an interesting material which exists in\natomically thin multilayers and can be exfoliated into monolayer or a few\nlayers for multiple applications. It has emerged as a promising material for\ndevelopment of such efficient sensors. Here, we have exfoliated and decorated\nMoS2 flakes with novel, single phase High Entropy Alloy (HEA) nanoparticles\nusing facile and scalable cryomilling technique, followed by sonochemical\nmethod. It is found that the decoration of HEA nanoparticles impart surface\nenhanced Raman scattering effect and reduction in the work function of the\nmaterial from 4.9 to 4.75 eV as measured by UV photoelectron spectroscopy. This\nchange in the work function results in a schottky barrier between the gold\ncontact and HEA decorated MoS2 flakes as a result of drastic changes in the\nsurface chemical non-stoichiometry. The response to hydrogen gas is studied at\ntemperatures 30 to 100 oC and it shows unusual p-type nature due to surface\nadsorbed oxygen species. The nanoscale junction formed between HEA and MoS2\nshows 10 times increase in the response towards hydrogen gas at 80 oC. The\nexperimental observations are further explained with DFT simulation showing\nmore favourable hydrogen adsorption on HEA decorated MoS2 resulting for\nenhanced response."
    },
    {
        "anchor": "Effect of Spin Orbit Coupling in non-centrosymmetric half-Heusler alloys: Spin-orbit coupled electronic structure of two representative non-polar\nhalf-Heusler alloys, namely 18 electron compound CoZrBi and 8 electron compound\nSiLiIn have been studied in details. An excursion through the Brillouin zone of\nthese alloys from one high symmetry point to the other revealed rich local\nsymmetry of the associated wave vectors resulting in non-trivial spin splitting\nof the bands and consequent diverse spin textures in the presence of spin-orbit\ncoupling. Our first principles calculations supplemented with low energy\n$\\boldsymbol{k.p}$ model Hamiltonian revealed the presence of linear\nDresselhaus effect at the X point having $D_{2d}$ symmetry and Rashba effect\nwith both linear and non-linear terms at the L point with $C_{3v}$ point group\nsymmetry. Interestingly we have also identified non-trivial Zeeman spin\nsplitting at the non-time reversal invariant W point and a pair of\nnon-degenerate bands along the path $\\Gamma$ to L displaying vanishing spin\npolarization due to the non-pseudo polar point group symmetry of the wave\nvectors. Further a comparative study of CoZrBi and SiLiIn suggest, in addition,\nto the local symmetry of the wave vectors, important role of the participating\norbitals in deciding the nature and strength of spin splitting. Our\ncalculations identify half-Heusler compounds with heavy elements displaying\ndiverse spin textures may be ideal candidate for spin valleytronics where spin\ntextures can be controlled by accessing different valleys around the high\nsymmetry k-points.",
        "positive": "Fabrication and Characterization of Boron Carbide / n-Silicon Carbide\n  Heterojunction Diodes: The fabrication, initial structural characterization and diode measurements\nare reported for the first boron carbide / silicon carbide heterojunction\ndiode. Current-voltage curves obtained for operation at temperatures from 24 C\nto 388 C. PECVD-deposited undoped boron carbide material is highly crystalline\nand consists of a variety of polytypes of B-C with crystal sizes as large as\n110 nm. Crystal phases are similar to those for PECVD B-C on Si but only\npartially match known boron and boron-rich B-C phases."
    },
    {
        "anchor": "Structural and electronic properties of V$_2$O$_5$ and MoO$_3$ bulk and\n  ultrathin layers: The structural and electronic properties of bulk, monolayer and ultrathin\nfilms of V$_2$O$_5$ and MoO$_3$ layered oxides have been studied with\nfirst-principles density functional theory calculations including Van der Waals\ndispersion corrections. Specific DFT+U functionals have been tested in order to\nproperly reproduce geometry, band-gap, static dielectric constant, and\nformational enthalpies of the two materials. The mono-, and multi-layers are\ncleaved along the <001> and <010> stable crystallographic orientations for V2O5\nand MoO3, respectively. At least three layers are needed for both materials in\norder to recover bulk-like properties. Spin-orbit effects have been\nincorporated in our prediction, but they show marginal effects.",
        "positive": "Vibrational free energy and phase stability of paramagnetic and\n  antiferromagnetic CrN from ab-initio molecular dynamics: We present a theoretical first-principles method to calculate the free energy\nof a magnetic system in its high-temperature paramagnetic phase, including\nvibrational, electronic, and magnetic contributions. The method for calculating\nfree energies is based on ab-initio molecular dynamics and combines a treatment\nof disordered magnetism using disordered local moments molecular dynamics\n(DLM-MD) with the temperature dependent effective potential (TDEP) method to\nobtain the vibrational contribution to the free energy. We illustrate the\napplicability of the method by obtaining the anharmonic free energy for the\nparamagnetic cubic and the antiferromagnetic orthorhombic phases of chromium\nnitride. The influence of lattice dynamics on the transition between the two\nphases is demonstrated by constructing the temperature-pressure phase diagram."
    },
    {
        "anchor": "Efficient photogeneration of charge carriers in silicon nanowires with a\n  radial doping gradient: From electrodeless time-resolved microwave conductivity measurements, the\nefficiency of charge carrier generation, their mobility, and decay kinetics on\nphoto-excitation were studied in arrays of Si nanowires grown by the\nvapor-liquid-solid mechanism. A large enhancement in the magnitude of the\nphotoconductance and charge carrier lifetime are found depending on the\nincorporation of impurities during the growth. They are explained by the\ninternal electric field that builds up, due to a higher doped sidewalls, as\nrevealed by detailed analysis of the nanowire morphology and chemical\ncomposition.",
        "positive": "A review on the progress of polymer nanostructures with modulated\n  morphologies and properties, using nonporous AAO templates: Polymers with the same chemical composition can provide different properties\nby reducing the dimension or simply by altering their nanostructure. Recent\nliterature works report hundreds of examples of advances methods in the\nfabrication of polymer nanostructures accomplished following different\napproaches, soft lithography, self-assembly routes, template assisted methods,\netc. Polymer nanostructures with modulated morphologies and properties can be\neasily achieved from anodized aluminum oxide (AAO) templates assisted methods.\nIn the last decade, fabrication of polymer nanostructures in the nanocavities\nof AAO has raised a great interest since allows the control and tailoring of\ndimension of a huge number of polymer and polymer-based composites materials.\nThe fact that polymer dimension can be adjusted allow the study of\nsize-dependency properties. Moreover, modulated polymer nanostructures can be\ndesigned for specific applications from AAO templates methods. Taking into\naccount the last considerations, this review present an overview of recent and\nnew insights in the fabrication methods of polymer nanostructures from hard\nporous Anodic Aluminum Oxide (AAO) templates with emphasis on the study of\npolymer structure/property relationship at nanometric scale and stressing the\npotential interest in particular applications."
    },
    {
        "anchor": "Theory of a quantum-mechanical nucleation rate: classical vs. quantal\n  nucleation: We address problems arising in supersaturated systems of small atomic\nparticles in solids. Nucleation processes in such systems do not seem to follow\nthe classical interpretation but may be indicative of quantal nucleation\npartucularly at higher supersaturations. We reconcile Gibbs' free energy DeltaG\nvs. particle radius r dependence with the double-well oscillator energy vs.\nconfigurational coordinate q dependence to take advantage of the solution of a\nwell-known eigenvalue problem. Theoretical results are presented and compared\nwith experimental data.",
        "positive": "Robust high-fidelity DFT study of the lithium-graphite phase diagram: Graphite is the most widely used and among the most widely-studied anode\nmaterials for lithium-ion batteries. With increasing demands on lithium\nbatteries to operate at lower temperatures and higher currents, it is crucial\nto understand lithium intercalation in graphite due to issues associated with\nlithium plating. Lithium intercalation into graphite has been extensively\nstudied theoretically using density functional theory (DFT) calculations,\ncomplemented by experimental studies through X-ray diffraction, spectroscopy,\noptical imaging and other techniques. In this work, we present a first\nprinciples based model using DFT calculations, employing the BEEF-vdW as the\nexchange correlation functional, and Ising model to determine the phase\ntransformations and subsequently, the thermodynamic intercalation potential\ndiagram. We explore a configurational phase space of about 1 billion structures\nby accurately determining the important interactions for the Ising model. The\nBEEF-vdW exchange correlation functional employed accurately captures a range\nof interactions including vdW, covalent and ionic interactions. We incorporate\nphonon contributions at finite temperatures and configurational entropy to get\nhigh accuracy in free energy and potentials. We utilize the built-in error\nestimation capabilities of the BEEF-vdW exchange correlation functional and to\ndevelop a methodological framework for determining the uncertainty associated\nwith DFT calculated phase diagrams and intercalation potentials. The framework\nalso determines the confidence of each predicted stable phase. The confidence\nvalue of a phase can help us to identify regions of solid solutions and phase\ntransformations accurately."
    },
    {
        "anchor": "Positron lifetime calculation of the elements of the periodic table: Theoretical positron lifetime values have been calculated systematically for\nmost of the elements of the Periodic Table. Self-consistent and\nnon-self-consistent schemes have been used for the calculation of the\nelectronic structure in the solid, as well as different parameterizations for\nthe positron enhancement factor and correlation energy. The results obtained\nhave been studied and compared with experimental data, confirming the\ntheoretical trends. As it is known, positron lifetimes in bulk show a periodic\nbehaviour with atomic number. These calculations also confirm that monovacancy\nlifetimes follow the same behaviour. From this fact a strong relation between\nthe atomic volume and the positron lifetime has been set. The effects of\nenhancement factors used in calculations have been commented. Finally, we have\nanalysed the effects that f and d electrons cause in positron lifetimes.",
        "positive": "Progress and Challenges in Ab Initio Simulations of Quantum Nuclei in\n  Weakly Bonded Systems: Atomistic simulations based on the first-principles of quantum mechanics are\nreaching unprecedented length scales. This progress is due to the growth in\ncomputational power allied with the development of new methodologies that allow\nthe treatment of electrons and nuclei as quantum particles. In the realm of\nmaterials science, where the quest for desirable emergent properties relies\nincreasingly on soft weakly-bonded materials, such methods have become\nindispensable. In this perspective, an overview of simulation methods that are\napplicable for large system sizes and that can capture the quantum nature of\nelectrons and nuclei in the adiabatic approximation is given. In addition, the\nremaining challenges are discussed, especially regarding the inclusion of\nnuclear quantum effects (NQE) beyond a harmonic or perturbative treatment, the\nimpact of NQE on electronic properties of weakly-bonded systems, and how\ndifferent first-principles potential energy surfaces can change the impact of\nNQE on the atomic structure and dynamics of weakly bonded systems."
    },
    {
        "anchor": "Microcavity polariton light emitting diode: Cavity polaritons have been shown these last years to exhibit a rich variety\nof non-linear behaviors which could be used in new polariton based devices.\nOperation in the strong coupling regime under electrical injection remains a\nkey step toward a practical polariton device. We report here on the realization\nof a polariton based light emitting diode using a GaAs microcavity with doped\nBragg mirrors. Both photocurrent and electroluminescence spectra are governed\nby cavity polaritons up to 100 K.",
        "positive": "Fingerprints of Dirac points in first-principles scanning tunneling\n  spectra of graphene on a metal substrate: Graphene physisorbed on a metal has its characteristic Dirac cones preserved\nin the band-structure, but the Fermi level of the system is shifted due to the\ninteraction with the substrate. Based on density functional calculations with\nvan der Waals corrections, we present a method to determine the position of the\nDirac point with respect to the Fermi level from the measured scanning\ntunneling spectra (STS). It has been demonstrated that the dips in both\nsimulated local density of states and in the observed dI/dV profiles are indeed\nthe fingerprints of the Dirac points. The type and the level of doping can be\nthen inferred directly from the STS data without any additional experimental\ntechnique. Test calculations of graphene on a Cu(111) substrate have shown that\nthe predicted position of the Dirac point is in close proximity to the\nexperimental value reported in the recent studies. Moreover, simulations for\ngraphene on a Pt(111) surface allow us to explain the apparent contradictions\nin the state-of-the-art experimental works."
    },
    {
        "anchor": "A Phase Field Crystal Study of Solute Trapping: In this study we have incorporated two time scales into the phase field\ncrystal model of a binary alloy to explore different solute trapping properties\nas a function of crystal-melt interface velocity. With only diffusive dynamics,\nwe demonstrate that the segregation coefficient, K as a function of velocity\nfor a binary alloy is consistent with the model of Kaplan and Aziz where K\napproaches unity in the limit of infinite velocity. However, with the\nintroduction of wave like dynamics in both the density and concentration\nfields, the trapping follows the kinetics proposed by S. Sobolev[Phys. Rev. A.\n199:383386, 1995.], where complete trapping occurs at a finite velocity.",
        "positive": "Signatures of van Hove singularities in the anisotropic in-plane optical\n  conductivity of the topological semimetal Nb$_3$SiTe$_6$: We present a temperature-dependent infrared spectroscopy study on the layered\ntopological semimetal Nb$_3$SiTe$_6$ combined with density-functional theory\n(DFT) calculations of the electronic band structure and optical conductivity.\nOur results reveal an anisotropic behavior of the in-plane ($ac$-plane) optical\nconductivity, with three pronounced excitations located at around 0.15, 0.28,\nand 0.41~eV for the polarization of the incident radiation along the $c$ axis.\nThese excitations are well reproduced in the theoretical spectra. Based on the\n\\textit{ab initio} results, the excitations around 0.15 eV and 0.28 eV are\ninterpreted as fingerprints of van Hove singularities in the electronic band\nstructure and compared to the findings for other topological semimetals."
    },
    {
        "anchor": "X-ray natural circular dichroism: This paper discusses a theory of natural circular dichroism in the x-ray\nregion. Integrated spectra are interpreted in terms of microscopic effective\noperators, which are derived in the framework of a localised (atomic) model. It\nis shown that the generators of a de Sitter group, such as that introduced by\nGoshen and Lipkin for nuclear structure, are suitable for describing electronic\nproperties of non-centrosymmetric crystals.",
        "positive": "Orientation dependence of the nano-indentation behaviour of pure\n  tungsten: Coupling of nano-indentation and crystal plasticity finite element (CPFE)\nsimulations is widely used to quantitatively probe the small-scale mechanical\nbehaviour of materials. Earlier studies showed that CPFE can successfully\nreproduce the load-displacement curves and surface morphology for different\ncrystal orientations. Here, we report the orientation dependence of residual\nlattice strain patterns and dislocation structures in tungsten. For\norientations with one or more Burgers vectors close to parallel to the sample\nsurface, dislocation movement and residual lattice strains are confined to\nlong, narrow channels. CPFE is unable to reproduce this behaviour, and our\nanalysis reveals the responsible underlying mechanisms."
    },
    {
        "anchor": "Kondo Effect of a Jahn-Teller Ion Vibrating in a Cubic Anharmonic\n  Potential: We discuss the Kondo effect in a spinless two-orbital conduction electron\nsystem coupled with anharmonic Jahn-Teller vibration by employing a numerical\nrenormalization group technique. When a temperature $T$ is decreased, we\nencounter a plateau of $\\log 3$ entropy due to quasi-triple degeneracy of local\nlow-energy states, composed of vibronic ground states and the first excited\nstate with an excitation energy of $\\Delta E$. Around at $T$$\\approx$$\\Delta\nE$, we observe an entropy change from $\\log 3$ to $\\log 2$. This $\\log 2$\nentropy originates from the rotational degree of freedom of the vibronic state\nand it is eventually released due to the screening by orbital moments of\nconduction electrons, leading to the Kondo effect of a Jahn-Teller ion. The\nKondo temperature is explained by the effective $s$-$d$ model with anisotropic\nexchange interactions.",
        "positive": "The demagnetization factor for randomly packed spheroidal particles: We investigate if the demagnetization factor for a randomly packed powder of\nmagnetic spheroidal particles depend on the shape of the spheroidal particles\nand what the internal variation in magnetization is within such a powder. A\nspheroid is an ellipsoid of revolution, i.e. an ellipsoid with two semi-major\naxis being equal. The demagnetization factor is calculated as function of\nparticle aspect ratio using two independent numerical models for several\ndifferent packings, and assuming a relative permeability of 2. The calculated\ndemagnetization factor is shown to depend on particle aspect ratio, not because\nof direct magnetic interaction but because the particle packing depend on the\naspect ratio of the particles. The relative standard deviation of the\nmagnetization across the powder was 3\\%-8\\%, increasing as the particle shape\ndeviates from spherical, while the relative standard deviation within each\nparticle was relatively constant around 5\\%."
    },
    {
        "anchor": "Generalized stacking fault energy surfaces and dislocation properties of\n  aluminum: We have employed the semidiscrete variational generalized Peierls-Nabarro\nmodel to study the dislocation core properties of aluminum. The generalized\nstacking fault energy surfaces entering the model are calculated by using\nfirst-principles Density Functional Theory (DFT) with pseudopotentials and the\nembedded atom method (EAM). Various core properties, including the core width,\nsplitting behavior, energetics and Peierls stress for different dislocations\nhave been investigated. The correlation between the core energetics and\ndislocation character has been explored. Our results reveal a simple\nrelationship between the Peierls stress and the ratio between the core width\nand atomic spacing. The dependence of the core properties on the two methods\nfor calculating the total energy (DFT vs. EAM) has been examined. The EAM can\ngive gross trends for various dislocation properties but fails to predict the\nfiner core structures, which in turn can affect the Peierls stress\nsignificantly (about one order of magnitude).",
        "positive": "Mapping Skyrmion Stability in Uniaxial Lacunar Spinel Magnets from\n  First-Principles: The identification of general principles for stabilizing magnetic skyrmion\nphases in bulk materials over wide ranges of temperatures is a prerequisite to\nthe development of skyrmion-based spintronic devices. Lacunar spinels with the\nformula GaM4X8 with M=V, Mo; X=S, Se are a convenient case study towards this\ngoal as they are some of the first bulk systems suggested to host equilibrium\nchiral skyrmions far from the paramagnetic transition. We derive the magnetic\nphase diagrams likely to be observed in these materials, accounting for all\npossible magnetic interactions, and prove that skyrmion stability in the\nlacunar spinels is a general consequence of their crystal symmetry rather than\nthe details of the material chemistry. Our results are consistent with all\nexperimental reports in this space and demonstrate that the differences in the\nphase diagrams of particular spinel chemistries are determined by\nmagnetocrystalline anisotropy, up to a normalization factor. We conclude that\nskyrmion formation over wide ranges of temperatures can be expected in all\nlacunar spinels, as well as in a wide range of uniaxial systems with low\nmagnetocrystalline anisotropy."
    },
    {
        "anchor": "Origin of the structural phase transition in Li7La3Zr2O12: Garnet-type Li7La3Zr2O12 (LLZO) is a solid electrolyte material with a\nlow-conductivity tetragonal and a high-conductivity cubic phase. Using\ndensity-functional theory and variable cell shape molecular dynamics\nsimulations, we show that the tetragonal phase stability is dependent on a\nsimultaneous ordering of the Li ions on the Li sublattice and a\nvolume-preserving tetragonal distortion that relieves internal structural\nstrain. Supervalent doping introduces vacancies into the Li sublattice,\nincreasing the overall entropy and reducing the free energy gain from ordering,\neventually stabilizing the cubic phase. We show that the critical temperature\nfor cubic phase stability is lowered as Li vacancy concentration (dopant level)\nis raised and that an activated hop of Li ions from one crystallographic site\nto another always accompanies the transition. By identifying the relevant\nmechanism and critical concentrations for achieving the high conductivity\nphase, this work shows how targeted synthesis could be used to improve\nelectrolytic performance.",
        "positive": "Probing Localized Surface Plasmons of Trisoctahedral Gold Nanocrystals\n  for Surface Enhanced Raman Scattering: Trisoctahedral (TOH) shaped Au nanocrystals (NCs) have emerged as a new class\nof metal nanoparticles (MNP) due to its superior catalystic and SERS activities\ncaused by the presence of high density atomic steps and dangling bonds on their\nhigh index facets. We examine the radiative localized surface plasmon resonance\n(LSPR) modes of an isolated single TOH Au NC using cathodoluminescence (CL),\nwith high resolution spatial information of the local density of optical states\n(LDOS) across the visible spectral range. Further we show pronounced\nenhancement factor in the Raman scattering by performing Raman spectroscopic\nmeasurements on Rhodamine 6G (R6G) covered TOH Au NPs aggregates on a Si\nsubstrate. We believe that the hot spots between two adjacent MNP surfaces\n(nanogaps) can be significantly stronger than single particle LSPRs. Such\nnanogaps hotspots may have crucial role on the substantial SERS enhancement\nobserved in this report. Consequently, the present study indicates that MNPs\naggregates are highly desirable than individual plasmonic nanoparticles for\npossible applications in SERS based biosensing."
    },
    {
        "anchor": "Coupled Negative magnetocapacitance and magnetic susceptibility in a\n  Kagome staircase-like compound Co3V2O8: The dielectric constant of the Kagome staircase-like Co3V2O8 polycrystalline\ncompound has been measured as function of temperature and magnetic field up to\n14T. It is found that the application of an external magnetic field suppresses\nthe anomaly for the dielectric constant beyond 6.1K. Furthermore, its magnetic\nfield dependence reveals a negative magnetocapacitance which is proportional to\nthe magnetic susceptibility, suggesting a common magnetostrictive origin for\nthe magnetic field dependence of the two quantities. This result is very\ndifferent from that obtained from the isostructural compound Ni3V2O8 that\npresents a peak in the dielectric constant at the incommensurate magnetic phase\ntransition coupled to a sign change of the magnetocapacitance.",
        "positive": "Ultrasonic monitoring of stress and cracks of the 1/3 scale mock-up of\n  nuclear reactor concrete containment structure: To evaluate the stress level and damage of a reinforced concrete containment\nwall and its reaction to pressure variations, we implemented successive\nultrasonic experiments on the exterior surface of the containment wall in the\ngusset area for three consecutive years. During each experiment, the pressure\ninside the containment wall increased gradually from 0 MPa to 0.43 MPa and then\ndecreased back to 0 Mpa.From the analysis of the ultrasonic coda waves obtained\nin the multiple scattering regime, we performed Coda Wave Interferometry to\ncalculate the apparent velocity changes in the structure (denoted by $dV/V_a$)\nand Coda Wave Decorrelation (DC) measurements to produce 3D cartographies of\nstress and crack distribution. From three source-receiver pairs, located at the\ntop, middle and bottom of the experimental region, we observe that coda waves\ndilate, shrink and remain almost unchanged, respectively. This corresponds to\nthe decreasing, increasing and invariant pressure inside the concrete. The\ncomparison of three years' results demonstrates that the variation of $dV/V_a$\nand DC under the same pressure test increases through the years, which\nindicates the progressive deterioration and aging of the concrete. From a large\ncollection of source-receiver pairs at different times, the spatial-temporal\nvariations of $dV/V_a$ and DC are then used to produce a map of the structural\nvelocity and scattering changes, respectively. We observe a decreasing velocity\non the top part and an increasing in the middle one, which is in line with the\n$dV/V_a$ analysis. The reconstructed scattering changes (or structural changes)\nhighlight the active region during the inflation-deflation procedure,\ncorresponding to the opening and closing (and sometimes the development) of\ncracks. The larger magnitude in 2019 than in 2017 indicates the increasing\ndamage in the concrete."
    },
    {
        "anchor": "Rapid suppression of charge density wave transition in LaSb2 under\n  pressure: LaSb2 is found to be an example of an exceptionally pressure sensitive and\ntunable, two dimensional compound. In-plane electrical resistivity of LaSb2\nunder pressure up to 12.9 kbar was measured in zero and applied magnetic field.\nThe charge density wave transition (observed at ~ 350 K at ambient pressure) is\ncompletely suppressed by 6-7 kbar with significant (in comparison with the\nambient pressure) increase in Fermi surface gapping and transition hysteresis\njust above ambient pressure.",
        "positive": "Inherent heating instability of direct microwave sintering process:\n  Sample analysis for porous 3Y-ZrO2: Direct microwave heating of 3Y-ZrO 2 is studied at frequency of 2.45 GHz.\nDifferent conditions of input power, sample position and size are tested. For\nthe first time, the experimentally known instability of microwave sintering is\nexplained coupling the effective medium approximation and finite-element\nmethod. We show how the material dielectric permittivity imaginary part which\nincreases with temperature and relative density encourages high hot spot\nphenomena. It is shown that the sample location has a great impact on the"
    },
    {
        "anchor": "Macroscopic signature of protected spins in a dense frustrated magnet: The inability of systems of interacting objects to satisfy all constraints\nsimultaneously leads to frustration. A particularly important consequence of\nfrustration is the ability to access certain protected parts of a system\nwithout disturbing the others. For magnets such \"protectorates\" have been\ninferred from theory and from neutron scattering, but their practical\nconsequences have been unclear. We show that a magnetic analogue of optical\nhole-burning can address these protected spin clusters in a well-known,\ngeometrically frustrated Heisenberg system, gadolinium gallium garnet. Our\nmeasurements additionally provide a resolution of a famous discrepancy between\nthe bulk magnetometry and neutron diffraction results for this magnetic\ncompound.",
        "positive": "Strength-dependent Transition of Graphite Under Shock Condition Resolved\n  by First Principles: The shock strength dependent formation of diamond represents one of the most\nintriguing questions in graphite research. Using ab initio DFT-trained carbon\nGNN model, we observe a strength-dependent graphite transition under shock. The\npoor sliding caused by scarce sliding time under high-strength shock forms\nhexagonal diamond with an orientation of (001)G//(100)HD+[010]G//[010]HD; under\nlow-strength shock, cubic diamond forms after enough sliding time, unveiling\nthe strength-dependent graphite transition. We provide computational evidence\nof the strength-dependent graphite transition from first principles, clarifying\nthe long-term shock-induced hexagonal formation and structural\nstrength-dependent trend source."
    },
    {
        "anchor": "Lamellar Phases in Nonuniform Electric Fields: Breaking the In-Plane\n  Rotation Symmetry and the Role of Dielectric Constant Mismatch: We consider orientational transitions of lamellar phases under the influence\nof a spatially nonuniform electric field. The transition between parallel and\nperpendicular lamellar stackings with respect to the substrate is investigated\nas a function of the system parameters. The dielectrophoretic energy and the\nenergy penalty for having dielectric interfaces perpendicular to the field's\ndirection are identified as linear and quadratic terms in a free energy\nexpansion in the dielectric constant mismatch. We find that if the dielectric\nconstant mismatch $\\Delta\\eps$ is smaller than some critical value\n$\\Delta\\eps_c$, parallel lamellar stacking will be realized, no matter how\nlarge the voltage difference between electrodes is. At\n$\\Delta\\eps>\\Delta\\eps_c$, perpendicular stacking will appear if the voltage is\nhigh enough. Nonuniform fields remove the in-plane degeneracy present in the\nmore common uniform fields. We therefore calculate the energy of grains of\ndifferent orientations. The torque acting on the grains leads to the preference\nof only one orientation. The results have direct implications to block\ncopolymer orientation and to surface patterning on the nanometer scale.",
        "positive": "Analytical spectral-domain scattering theory of a general gyrotropic\n  sphere: We propose an analytical scattering theory in spectral domain to model the\nelectromagnetic (EM) fields of a gyrotropic sphere in terms of the\neigen-functions and their associated spectral eigenvalues/coefficients in a\nrecursive integral form. Applying the continuous boundary conditions of\nelectromagnetic fields on the surface between the free space and gyrotropic\nsphere, the spectral coefficients of transmitted fields inside the gyrotropic\nsphere and the scattered fields in the isotropic host medium can be obtained\nexactly by expanding spherical vector wave eigenfunctions. Numerical results\nare provided for some representative cases, which are compared to the results\nfrom adaptive integral method (AIM). Good agreement demonstrates the validity\nof the proposed analytical scattering theory for gyrotropic spheres in spectral\ndomain using Fourier transform."
    },
    {
        "anchor": "Breathing bands due to molecular order in CH3NH3PbI3: CH3NH3PbI3 perovskite is nowadays amongst the most promising photovoltaic\nmaterials for energy conversion. We have studied by ab-initio calculations,\nusing several levels of approximation - namely density functional theory\nincluding spin-orbit coupling and quasi-particle corrections by means of the GW\nmethod, as well as pseudopotential self-interaction corrections -, the role of\nthe methylammonium orientation on the electronic structure of this perovskite.\nWe have considered many molecular arrangements within 2x2x2 supercells, showing\nthat the relative orientation of the organic molecules is responsible for a\nhuge band gap variation up to 2 eV. The band gap sizes are related to\ndistortions of the PbI3 cage, which are in turn due to electrostatic\ninteractions between this inorganic frame and the molecules. The strong\ndependence of the band gap on the mutual molecular orientation is confirmed at\nall levels of approximations. Our results suggest then that the coupling\nbetween the molecular motion and the interactions of the molecules with the\ninorganic cage could help to explain the widening of the absorption spectrum of\nCH3NH3PbI3 perovskite, consistent with the observed white spectrum.",
        "positive": "Pressure-tunable large anomalous Hall effect of the ferromagnetic\n  kagome-lattice Weyl semimetal Co3Sn2S2: We investigate the pressure evolution of the anomalous Hall effect in\nmagnetic topological semimetal Co3Sn2S2 in diamond anvil cells with pressures\nup to 44.9-50.9 GPa. No evident trace of structural phase transition is\ndetected through synchrotron x-ray diffraction over the measured pressure range\nof 0.2-50.9 GPa. We find that the anomalous Hall resistivity and the\nferromagnetism are monotonically suppressed as increasing pressure and almost\nvanish around 22 GPa. The anomalous Hall conductivity varies non-monotonically\nagainst pressure at low temperatures, involving competition between original\nand emergent Weyl nodes. Combined with first-principle calculations, we reveal\nthat the intrinsic mechanism due to the Berry curvature dominates the anomalous\nHall effect under high pressure."
    },
    {
        "anchor": "Lessons from the harmonic oscillator -- a reconciliation of the\n  Frequency-Resolved Frozen Phonon Multislice Method with other theoretical\n  approaches: We compare the Frequency-Resolved Frozen Phonon Multislice (FRFPMS) method,\nintroduced in Phys. Rev. Lett. 124, 025501 (2020), with other theoretical\napproaches used to account for the inelastic scattering of high energy\nelectrons, namely the first-order Born approximation and the quantum excitation\nof phonons model. We show, that these theories lead to similar expressions for\nthe single inelastically scattered intensity as a function of momentum transfer\nfor an anisotropic quantum harmonic oscillator in a weak phase object\napproximation of the scattered waves, except for a too small smearing of the\nscattering potential by the effective Debye-Waller factor (DWF) in the FRFPMS\nmethod. We propose that this issue can be fixed by including an explicit DWF\nsmearing into the potential and demonstrate numerically, that in any realistic\nsituation, a FRFPMS approach revised in this way, correctly accounts for the\nsingle inelastically scattered intensity and the correct elastic scattering\nintensity. Furthermore our simulations illustrate that the only requirement for\nsuch a revised FRFPMS method is the smallness of mean squared displacements for\nall atomic species in all frequency bins. The analytical considerations for the\nFRFPMS method also explain the $1/\\omega^2$-scaling of FRFPMS spectra observed\nin Phys. Rev. B 104, 104301 (2021) by the use of classical statistics in the\nmolecular dynamics simulation. Moreover, we find that the FRFPMS method\ninherently adds the contributions of phonon loss and gain within each frequency\nbin. Both of these issues related to the frequency-scaling can be fixed by a\nsystem-independent post-processing step.",
        "positive": "Resolving the Dirac Cone on the Surface of Bi2Te3 Topological Insulator\n  Nanowires by Field-Effect Measurements: We validate the linear dispersion relation and resolve the Dirac cone on the\nsurface of a single Bi2Te3 nanowire via a combination of field-effect and\nmagnetoresistance measurements by which we unambiguously prove the topological\ninsulator nature of the nanowire surface states. Moreover we show that the\nexperimentally determined carrier concentration, mobility and cyclotron mass of\nthe surface states are in excellent agreement with relativistic models. Our\nmethod provides a facile way to identify topological insulators that too small\nfor angle-resolved photo emission spectroscopy."
    },
    {
        "anchor": "Silicon clathrates for photovoltaics predicted by a two-step crystal\n  structure search: Silicon in a cubic diamond structure currently plays a significant role in\nthe photovoltaic industry. However, the intrinsic band structures of\ncrystalline silicon restrict its sunlight conversion efficiency. Recently, a\nclathrate-like Si-24 has been successfully synthesized, which has a\nquasi-direct bandgap and sheds light on silicon-based photovoltaics. Here, we\nproposed a two-step crystal structure search method based on first-principles\ncalculations and explored silicon clathrate structures extensively. First, the\nguest-host compounds were searched at high pressure, and then, the porous\nguest-free silicon clathrates were obtained by removing the guest atoms. Using\npotassium as the guest atom, we identified four metastable silicon clathrate\nstructures, and some of them have bandgaps close to the optimal range of the\nShockley-Queisser limit and have a better absorption rate than the cubic\ndiamond silicon. These silicon clathrates may have promising value in\nphotovoltaic applications.",
        "positive": "A new porous metallic silicon dicarbide for highly efficient Li-ion\n  battery anode identified by targeted structure search: Extensive efforts have been devoted to C-Si compound materials for improving\nthe limited specific capacity of graphite anode and avoiding the huge volume\nchange of Si anode in Li-ion battery, but not much progress has been made\nduring the past decades. Here, for the first time we apply the targeted\nstructure search by using Li in desired quantity as chemical template to\nregulate the bonding between C and Si, which makes searching more feasible for\nus to find a new stable phase of C2Si (labelled as T-C2Si) that can better fit\nthe XRD data of silicon dicarbide synthesized before. Different from the\nconventional semiconducting silicon carbides, T-C2Si is not only metallic with\nhigh intrinsic conductivity for electrons transport, but also porous with\nregularly distributed channels in suitable size for Li ions experiencing a low\nenergy barrier. T-C2Si exhibits a high specific capacity of 515 mA/g, a high\naverage open-circuit voltage of 1.14 eV, and a low volume change of 1.6%. These\nparameters meet the requirements of an ideal anode material with high\nperformance for electric vehicles. Moreover, our targeted search strategy\nguarantees the resulting anode material with a desirable specific capacity and\na small volume change during charging /discharging, and it can be used to find\nnew geometric configurations for other materials."
    },
    {
        "anchor": "The Effects of a Non-Ferroelectric Slab on the Polarization and the\n  Susceptibility of the Ferroelectric Multilayer: The polarization and the susceptibility of a ferroelectric multilayer with a\nnon-ferroelectric slab are investigated within the framework of transverse\nIsing model with a four-spin interaction term. The effect of the thickness and\nthe position of the non-ferroelectric slab are investigated in this paper. We\nfind that the increase of the thickness of the non-ferroelectric will decrease\nthe polarization and the susceptibility of the film. If the position of the\nnon-ferroelcetric slab shifts from the center of the film to the surface, the\nnumber of the peaks of the susceptibility will change. And a step-like\npolarization curve is found.",
        "positive": "Polarization fluctuations in insulators and metals: New and old theories\n  merge: The ground-state fluctuation of polarization P is finite in insulators and\ndivergent in metals, owing to the SWM sum rule [I. Souza, T. Wilkens, and R. M.\nMartin, Phys. Rev. B 62, 1666 (2000)]. This is a virtue of periodic (i.e.\ntransverse) BCs. I show that within any other boundary conditions the P\nfluctuation is finite even in metals, and a generalized sum rule applies. The\nboundary-condition dependence is a pure correlation effect, not present at the\nindependent-particle level. In the longitudinal case div P = -rho, and one\nequivalently addresses charge fluctuations: the generalized sum rule reduces\nthen to a well known result of many-body theory."
    },
    {
        "anchor": "Crystal plasticity model of residual stress in additive manufacturing: Selective laser melting is receiving increasing interest as an additive\nmanufacturing technique. Residual stresses induced by the large temperature\ngradients and inhomogeneous cooling process can favour the generation of\ncracks. In this work, a crystal plasticity finite element model is developed to\nsimulate the formation of residual stresses and to understand the correlation\nbetween plastic deformation, grain orientation and residual stresses in the\nadditive manufacturing process. The temperature profile and grain structure\nfrom thermal-fluid flow and grain growth simulations are implemented into the\ncrystal plasticity model. An element elimination and reactivation method is\nproposed to model the melting and solidification and to reinitialise state\nvariables, such as the plastic deformation, in the reactivated elements. The\naccuracy of this method is judged against previous method based on the\nstiffness degradation of liquid regions by comparing the plastic deformation as\na function of time induced by thermal stresses. The method is used to\ninvestigate residual stresses parallel and perpendicular to the laser scan\ndirection, and the correlation with the maximum Schmid factor of the grains\nalong those directions. The magnitude of the residual stress can be predicted\nas a function of the depth, grain orientation and position with respect to the\nmolten pool.",
        "positive": "Above-Room-Temperature Ferromagnetism in GaSb/Mn Digital Alloys: Digital alloys of GaSb/Mn have been fabricated by molecular beam epitaxy.\nTransmission electron micrographs showed good crystal quality with individual\nMn-containing layers well resolved; no evidence of 3D MnSb precipitates was\nseen in as-grown samples. All samples studied exhibited ferromagnetism with\ntemperature dependent hysteresis loops in the magnetization accompanied by\nmetallic p-type conductivity with a strong anomalous Hall effect (AHE) up to\n400 K (limited by the experimental setup). The anomalous Hall effect shows\nhysteresis loops at low temperatures and above room temperature very similar to\nthose seen in the magnetization. The strong AHE with hysteresis indicates that\nthe holes interact with the Mn spins above room temperature. All samples are\nmetallic, which is important for spintronics applications.\n  * To whom correspondence should be addressed. E-mail: luo@buffalo.edu"
    },
    {
        "anchor": "Graphene based quantum dots: Laterally localized electronic states are identified on a single layer of\ngraphene on ruthenium. The individual states are separated by 3 nm and comprise\nregions of about 90 carbon atoms. This constitutes a quantum dot array,\nevidenced by quantum well resonances that are modulated by the corrugation of\nthe graphene layer. The quantum well resonances are strongest on the isolated\n\"hill\" regions where the graphene is decoupled from the surface. This peculiar\nnanostructure is expected to become important for single electron physics where\nit bridges zero-dimensional molecule-like and two-dimensional graphene on a\nhighly regular lattice.",
        "positive": "Large-Gap Quantum Spin Hall State and Temperature-Induced Lifshitz\n  Transition in Bi4Br4: Searching for new quantum spin Hall insulators with large fully opened energy\ngap to overcome the thermal disturbance at room temperature has attracted\ntremendous attention due to the one-dimensional (1D) spin-momentum locked\ntopological edge states serving as dissipationless channels for the practical\napplications in low consumption electronics and high performance spintronics.\nHere, we report the investigation of topological nature of monolayer Bi4Br4 by\nthe techniques of scanning tunneling microscopy and angle-resolved\nphotoemission spectroscopy (ARPES). The topological non-triviality of 1D edge\nstate integrals within the large bulk energy gap (~ 0.2 eV) is revealed by the\nfirst-principle calculations. The ARPES measurements at different temperature\nshow a temperature-induced Lifshitz transition, corresponding to the\nresistivity anomaly caused by the shift of chemical potential. The connection\nbetween the emergency of superconductivity and the Lifshitz transition is\ndiscussed."
    },
    {
        "anchor": "Non-Gaussian diffusion profiles caused by mobile impurity-vacancy pairs\n  in the five frequency model of diffusion: Vacancy-mediated diffusion of impurities under strong impurity-vacancy (I-v)\nattraction has been studied in the framework of the five-frequency model (5FM)\nfor the FCC host. The system of impurities and tightly bound I-v pairs has been\ntreated in the framework of the rate-equations approach of Cowern et al., Phys.\nRev. Lett. 65, 2434 (1990), developed for the description of the non-Gaussian\ndiffusion profiles (NGDPs) observed in dopant diffusion in silicon. In the\npresent study this approach has been extended to derive a three-dimensional\n(3D) integro-differential equation describing the pair-mediated impurity\ndiffusion. The equation predicts the same 1D NGDPs as in Cowern et al. but can\nbe also used for the simulation of 3D profiles of arbitrary geometry in the\nsystems where the diffusion proceeds via a mobile state. The parameters of the\ntheory has been calculated within the 5FM on the basis of available literature\ndata. The database on impurities in aluminum host has been analyzed and\npromising impurity-host systems for the observation of NGDPs has been\nidentified. The diffusion profiles for an impurity where NGDPs are expected to\nbe easily detectable have been simulated. It has been argued that with the\ninput parameters calculated on the basis of experimental diffusion constants\nthe simulated NGDPs can be accurate enough to serve as a quantitative test of\nthe 5FM.",
        "positive": "Local Field effects on the radiative lifetime of emitters in surrounding\n  media: virtual- or real-cavity model?: For emitters embedded in media of various refractive indices, different\nmacroscopic or microscopic theoretical models predict different dependencies of\nthe spontaneous emission lifetime on refractive index. Among those models are\nthe two most promising models: the virtual-cavity model and the real-cavity\nmodel. It is a priori not clear which model is more relevant for a given\nsituation. By close analysis of the available experimental results and\nexamining the assumptions underlying the two models, we reach a consistent\ninterpretation of the experimental results and give the criteria which model\nshould apply for a given situation."
    },
    {
        "anchor": "Stable two-dimensional ferromagnets made of regular single-layered\n  lattices of single-molecule nanomagnets on substrates: We propose that stable two-dimensional (2D) ferromagnets can be made of\nregular single-layered lattices of single-molecule nanomagnets with enough\nuniaxial magnetic anisotropy on appropriate substrates by controlling the\ninter-nanomagnet magnetic interaction. Our Monte Carlo simulated results show\nthat such ideal 2D ferromagnets are thermodynamically stable when the\nanisotropy is strong enough. If the anisotropy energy equals 80 K,\napproximately that of the Mn12, the T_c varies from zero to 15 K depending on\ndifferent inter-nanomagnet coupling constants. Such stable spin systems,\nexperimentally accessible, should be promising for information applications.",
        "positive": "Towards a simplified description of thermoelectric materials: Accuracy\n  of approximate density functional theory for phonon dispersions: We calculate the phonon-dispersion relations of several two-dimensional\nmaterials and diamond using the density-functional based tight-binding approach\n(DFTB). Our goal is to verify if this numerically efficient method provides\nsufficiently accurate phonon frequencies and group velocities to compute\nreliable thermoelectric properties. To this end, the results are compared to\navailable DFT results and experimental data. To quantify the accuracy for a\ngiven band, a descriptor is introduced that summarizes contributions to the\nlattice conductivity that are available already in the harmonic approximation.\nWe find that the DFTB predictions depend strongly on the employed repulsive\npair-potentials, which are an important prerequisite of this method. For\ncarbon-based materials, accurate pair-potentials are identified and lead to\nerrors of the descriptor that are of the same order as differences between\ndifferent local and semi-local DFT approaches."
    },
    {
        "anchor": "Observation of Coexisting Dirac Bands and Moir\u00e9 Flat Bands in\n  Magic-Angle Twisted Trilayer Graphene: Moir\\'e superlattices that consist of two or more layers of two-dimensional\nmaterials stacked together with a small twist angle have emerged as a tunable\nplatform to realize various correlated and topological phases, such as Mott\ninsulators, unconventional uperconductivity and quantum anomalous Hall effect.\nRecently, the magic-angle twisted trilayer graphene (MATTG) has shown both\nrobust superconductivity similar to magic-angle twisted bilayer graphene\n(MATBG) and other unique properties, including the Pauli-limit violating and\nre-entrant superconductivity. These rich properties are deeply rooted in its\nelectronic structure under the influence of distinct moir\\'e potential and\nmirror symmetry. Here, combining nanometer-scale spatially resolved\nangle-resolved photoemission spectroscopy (nano-ARPES) and scanning tunneling\nmicroscopy/spectroscopy (STM/STS), we systematically measure the yet unexplored\nband structure of MATTG near charge neutrality. Our measurements reveal the\ncoexistence of the distinct dispersive Dirac band with the emergent moir\\'e\nflat band, showing nice agreement with the theoretical calculations. These\nresults serve as a stepstone for further understanding of the unconventional\nsuperconductivity in MATTG.",
        "positive": "Strain-based Spin Manipulation on Substitutional Nickel in Silicon\n  Carbide: By using the full potential linear augmented plane wave (FP-LAPW) method and\nfull potential local orbital minimum basis (FP-LOMB) method within generalized\ngradient approximation (GGA), we studied the electronic structures and magnetic\nproperties of nickel and chromium single dopants in polytypes of silicon\ncarbide (SiC). The magnetic phases of defects are found to be strongly\ndependent on the external stress on the supercell. In 3C-SiC, the Ni single\ndopant exhibits an anti-ferromagnetic (AFM) to ferromagnetic (FM) transition at\na moderate compressive and tensile hydrostatic strain in Si-sub and C-sub\ncases. In contrast, the Ni single dopant in 4H-SiC is stably in the nonmagnetic\nphase under external stress. The Cr single dopant is also insensitive to the\napplied stress but stably in the magnetic phase. This strain controlled\nmagnetic transition makes the Ni single dopant a novel scheme of qubit."
    },
    {
        "anchor": "Solid phase crystallization under continuous heating: kinetic and\n  microstructure scaling laws: The kinetics and microstructure of solid-phase crystallization under\ncontinuous heating conditions and random distribution of nuclei are analyzed.\nAn Arrhenius temperature dependence is assumed for both nucleation and growth\nrates. Under these circumstances, the system has a scaling law such that the\nbehavior of the scaled system is independent of the heating rate. Hence, the\nkinetics and microstructure obtained at different heating rates differ only in\ntime and length scaling factors.Concerning the kinetics, it is shown that the\nextended volume evolves with time according to alpha_ex=[exp(kappa Ct)]^m+1,\nwhere t' is the dimensionless time. This scaled solution not only represents a\nsignificant simplification of the system description, it also provides new\ntools for its analysis. For instance, it has been possible to find an\nanalytical dependence of the final average grain size on kinetic parameters.\nConcerning the microstructure, the existence of a length scaling factor has\nallowed the grain-size distribution to be numerically calculated as a function\nof the kinetic parameters.",
        "positive": "Origin of Wake-Up Effect in Hafnia: We performed density functional theory (DFT) calculations on epitaxially\nstrained hafnia. We demonstrate the stabilization of the ferroelectric\n($Pca2_{1}$) phase from the antiferroelectric ($Pbcn$) in bulk hafnia in the\npresence of electric field. We found that the polar ($Pca2_{1}$) phase can be\nefficiently stabilized with an adequate choice of film orientation. We show\nthat for a (010)-oriented Pbcn, the ferroelectric $Pca2_{1}$ phase can be\nreached with a relatively small electric field ($\\mid\\varepsilon\\mid\\geq 150$\nKV/m). We thus provide a simple explanation to the experimental observation of\npolarization enhancement through electric field cycling, or wake-up effect, as\na ferroelectric phase transition driven by electric field. We find, in\ncontrast, that stress free pure hafnia does not become ferroelectric for any\nreasonable electric field. So we explain the wake up effect and stabilization\nof ferroelectric pure hafnia as coming from a combination of epitaxial strain\nunder applied electric field perpendicular to the film. We find that strain (or\ndoping) primarily destabilizes the baddeleyite structure, so that the\nantiferroelectric Pbcn and ferroelectric phases can form."
    },
    {
        "anchor": "Computational and experimental investigation of unreported transition\n  metal selenides and sulphides: Expanding the library of known inorganic materials with functional electronic\nor magnetic behavior is a longstanding goal in condensed matter physics and\nmaterials science. Recently, the transition metal chalchogenides including\nselenium and sulfur have been of interest because of their correlated-electron\nproperties, as seen in the iron based superconductors and the transition metal\ndichalcogenides. However, the chalcogenide chemical space is less explored than\nthat of oxides, and there is an open question of whether there may be new\nmaterials heretofore undiscovered. We perform a systematic combined theoretical\nand experimental search over ternary phase diagrams that are empty in the\nInorganic Crystal Structure Database containing cations, transition metals, and\none of selenium or sulfur. In these 27 ternary systems, we use a probabilistic\nmodel to reduce the likelihood of false negative predictions, which results in\na list of 24 candidate materials. We then conduct a variety of synthesis\nexperiments to check the candidate materials for stability. While the\nprediction method did obtain previously unknown compositions that are predicted\nstable within density functional theory, none of the candidate materials formed\nin our experiments. We come to the conclusion that these phase diagrams are\n\"empty\" in the case of bulk synthesis, but it remains a possibility that\nalternate synthesis routes may produce some of these phases.",
        "positive": "First-principles Study On The Electronic And Optical Properties Of Cubic\n  ABX3 Halide Perovskites: The electronic properties of ABX3 (A = Cs, CH3NH3, NH2CHNH2; B = Sn, Pb; X =\nCl, Br, I) type compounds in the cubic phase are systematically studied using\nthe first-principles calculations. We find that these compounds have direct\nband gaps at R point where the valance band maximum is an anti-bonding state of\nB s-X p coupling, while the conduction band minimum is a non-bonding state with\nB p characters. The chemical trend of their properties as A or B or X varies is\nfully investigated, which is of great importance to understand and optimize\nthis kind of solar cell materials. We find that: (i) as the size of A\nincreases, the band gap of ABX3 will increase; (ii) as B varies from Sn to Pb,\nthe band gap of ABX3 will increase; and (iii) as X ranges from Cl to Br to I,\nthe band gap will decrease. We explained these trends by analyzing their band\nstructures. Furthermore, optical properties of the ABX3 compounds are\ninvestigated. Our calculations show that taking into account the spin-orbit\ncoupling effect is crucial for predicting the accurate band gap of these halide\nperovskites. We predict that CH3NH3SnBr3 is a promising material for solar\ncells absorber with a perfect band gap and good optical absorption."
    },
    {
        "anchor": "Emergence of quantum critical behavior in metallic quantum-well states\n  of strongly correlated oxides: Controlling quantum critical phenomena in strongly correlated electron\nsystems, which emerge in the neighborhood of a quantum phase transition, is a\nmajor challenge in modern condensed matter physics. Quantum critical phenomena\nare generated from the delicate balance between long-range order and its\nquantum fluctuation. So far, the nature of quantum phase transitions has been\ninvestigated by changing a limited number of external parameters such as\npressure and magnetic field. We propose a new approach for investigating\nquantum criticality by changing the strength of quantum fluctuation that is\ncontrolled by the dimensional crossover in metallic quantum well (QW)\nstructures of strongly correlated oxides. With reducing layer thickness to the\ncritical thickness of metal-insulator transition, crossover from a Fermi liquid\nto a non-Fermi liquid has clearly been observed in the metallic QW of SrVO$_3$\nby \\textit{in situ} angle-resolved photoemission spectroscopy. Non-Fermi liquid\nbehavior with the critical exponent ${\\alpha} = 1$ is found to emerge in the\ntwo-dimensional limit of the metallic QW states, indicating that a quantum\ncritical point exists in the neighborhood of the thickness-dependent Mott\ntransition. These results suggest that artificial QW structures provide a\nunique platform for investigating novel quantum phenomena in strongly\ncorrelated oxides in a controllable fashion.",
        "positive": "Enhanced Electron Transport in Thin Copper Films via Atomic-Layer\n  Materials Capping: Using first-principles calculations based on density functional theory and\nnon-equilibrium Green's functions, we characterized the effect of surface\ntermination on the electronic transport properties of nanoscale Cu slabs. With\nideal, clean (111) surfaces and oxidized ones as baselines we explore the\neffect of capping the slabs with graphene, hexagonal boron nitrate, molybdenum\ndisulfide and stanene. Surface oxide suppresses balistic conductance by a\nfactor of 10 compared to the ideal surface. Capping the ideal copper surface\nwith graphene slightly increase conductance but MoS$_2$ and stanene have the\nopposite effect due to stronger interactions at the interface. Interestingly,\nwe find that capping atomistically roughed copper surfaces with graphene or\nMoS$_2$ decreases the resistance per unit length by 20 and 13%, respectively,\ndue to reduced scattering. The results presented in this work suggest that\ntwo-dimensional materials can be used as an ultra-thin liner in metallic\ninterconnect technology without increasing the interconnect line resistivity\nsignificantly."
    },
    {
        "anchor": "Ground state determination and band gaps of bilayers of graphenylenes\n  and octafunctionalized-biphenylenes: Device fabrication often requires materials that are either reliably\nconducting, reliably semiconducting, or reliably nonconducting. Bilayer\ngraphene (BLG) changes from a superconductor to a semiconductor depending on\nit's stacking, but because it is difficult to control its stacking, it is not a\nreliable material for device fabrication. Using DFTB+, this work demonstrates\nthat bilayers of graphenylene, net-C, and net-W can be reliably used for device\nfabrication without knowing the details of their stackings. Bilayers of\ngraphenylene and net-C are semiconducting for all sheer displacements, net-W is\nconducting for all sheer displacements, while that Type II, like BLG, is\nconducting or semiconducting depending on the sheer displacement. The method\nused gives bond lengths, unit cell dimensions, and band dispersion of\nsingle-layer graphene that are consistent with previously reported values, it\ncorrectly predicts that AB stacking is the ground state of BLG and gives an\ninterlayer separation that is consistent with previous studies. The bond\nlengths and lattice constants of the other carbon allotropes are consistent\nwith previously published values. \\textcolor{blue}{In order to calculate the\nband structures the bilayer systems,} DFTB+ was first used to determined the\ninterlayer separations of the 2-D carbon allotropes under shear displacement.",
        "positive": "Observation of the dynamic Jahn-Teller effect in the excited states of\n  nitrogen-vacancy centers in diamond: The optical transition linewidth and emission polarization of single\nnitrogen-vacancy (NV) centers are measured from 5 K to room temperature.\nInter-excited state population relaxation is shown to broaden the zero-phonon\nline and both the relaxation and linewidth are found to follow a T^5 dependence\nfor T up to 100 K. This dependence indicates that the dynamic Jahn-Teller\neffect is the dominant dephasing mechanism for the NV optical transitions at\nlow temperatures."
    },
    {
        "anchor": "Dielectrics in a time-dependent electric field: a real-time approach\n  based on density-polarization functional theory: In the presence of a (time-dependent) macroscopic electric field the electron\ndynamics of dielectrics cannot be described by the time-dependent density only.\nWe present a real-time formalism that has the density and the macroscopic\npolarization P as key quantities. We show that a simple local function of P\nalready captures long-range correlation in linear and nonlinear optical\nresponse functions. Specifically, after detailing the numerical implementation,\nwe examine the optical absorption, the second- and third-harmonic generation of\nbulk Si, GaAs, AlAs and CdTe at different level of approximation. We highlight\nlinks with ultranonlocal exchange-correlation functional approximations\nproposed within linear response time-dependent density functional theory\nframework.",
        "positive": "Light atom quantum oscillations in UC and US: High energy vibrational scattering in the binary systems UC and US is\nmeasured using time-of-flight inelastic neutron scattering. A clear set of\nwell-defined peaks equally separated in energy is observed in UC, corresponding\nto harmonic oscillations of the light C atoms in a cage of heavy U atoms. The\nscattering is much weaker in US and only a few oscillator peaks are visible. We\nshow how the difference between the materials can be understood by considering\nthe neutron scattering lengths and masses of the lighter atoms. Monte Carlo ray\ntracing is used to simulate the scattering, with near quantitative agreement\nwith the data in UC, and some differences with US. The possibility of observing\nanharmonicity and anisotropy in the potentials of the light atoms is\ninvestigated in UC. Overall the observed data is well accounted for by\nconsidering each light atom as a single atom isotropic quantum harmonic\noscillator."
    },
    {
        "anchor": "Polarization fields in nitride nanostructures: ten points to think about: Macroscopic polarization, both of intrinsic and piezoelectric nature, is\nunusually strong in III-V nitrides, and the built in electric fields in the\nlayers of nitride-based nanostructures, stemming from polarization changes at\nheterointerfaces, have a major impact on the properties of single and multiple\nquantum wells, high mobility transistors, and thin films. The concepts involved\nin the theory and applications of polarization in nitrides have encountered\nsome resistance in the field. Here we discuss critically ten ``propositions''\naimed at clarifying the main controversial issues.",
        "positive": "A significant influence of the substrate on the magnetic anisotropy of\n  monatomic nanowires: The magnetic anisotropy energy of Fe and Co monatomic nanowires both\nfree-standing and at the step edge of a Pt surface is investigated within the\nframework of the density-functional theory and local-spin-density (LSDA)\napproximation. Various types of the analysis of the calculated data reveal that\nthe spin-orbit interaction of the Pt atoms and the hybridization between the\nelectronic states have an important impact on the direction of the easy axis\nand on the magnitude of the magnetic anisotropy, both by a direct contribution\nlocalized at the Pt atoms and by an indirect contribution due to the\nmodification of the Co-localized part via hybridization effects."
    },
    {
        "anchor": "Bonding, Moment Formation, and Magnetic Interactions in Ca14MnBi11 and\n  Ba14MnBi11: The ``14-1-11'' phase compounds based on magnetic Mn ions and typified by\nCa14MnBi11 and Ba14MnBi11 show unusual magnetic behavior, but the large number\n(104) of atoms in the primitive cell has precluded any previous full electronic\nstructure study. Using an efficient, local orbital based method within the\nlocal spin density approximation to study the electronic structure, we find a\ngap between a bonding valence band complex and an antibonding conduction band\ncontinuum. The bonding bands lack one electron per formula unit of being\nfilled, making them low carrier density p-type metals. The hole resides in the\nMnBi4 tetrahedral unit and partially compensates the high spin d^5 Mn moment,\nleaving a net spin near 4 \\mu_B that is consistent with experiment. These\nmanganites are composed of two disjoint but interpenetrating `jungle gym'\nnetworks of spin 4/2 MnBi4^{9-} units with ferromagnetic interactions within\nthe same network, and weaker couplings between the networks whose sign and\nmagnitude is sensitive to materials parameters. Ca14MnBi11 is calculated to be\nferromagnetic as observed, while for Ba14MnBi11 (which is antiferromagnetic)\nthe ferro- and antiferromagnetic states are calculated to be essentially\ndegenerate. The band structure of the ferromagnetic states is very close to\nhalf metallic.",
        "positive": "Photoinduced electrification of solids. IV. Space charge effects\n  assessed: Our recent arXiv preprints have described the experimental evidence for the\nuniversal occurrence of short circuit photocurrents on illumination of solid\nstate surfaces by strongly absorbed light. A likely mechanism has been proposed\nbased on the photodesorption of surface ions to the surrounding atmosphere.\nAnalyses have been made of observed oscilloscope tracings of short circuit\nphoto voltages in terms of the linear rate theory in fair concomitance. Space\ncharge effects having been left unaccounted for, we now propose an approach to\nthem in the diffusion-free approximation."
    },
    {
        "anchor": "Thickness-dependent catalytic activity of hydrogen evolution based on\n  single atomic catalyst of Pt above MXene: Hydrogen as the cleanest energy carrier is a promising alternative renewable\nresource to fossil fuels. There is an ever-increasing interest in exploring\nefficient and cost-effective approaches of hydrogen production. Recent\nexperiments have shown that single platinum atom immobilized on the metal\nvacancies of MXenes allows a high-efficient hydrogen evolution reaction (HER).\nHere using ab initio calculations, we design a series of substitutional\nPt-doped Tin+1CnTx (Tin+1CnTx-PtSA) with different thicknesses and terminations\n(n = 1, 2 and 3, Tx = O, F and OH), and investigate the quantum-confinement\neffect on the HER catalytic performance. Surprisingly, we reveal a strong\nthickness effect of the MXene layer on the HER performance. Amongst the various\nsurface-terminated derivatives, Ti2CF2-PtSA and Ti2CH2O2-PtSA are found to be\nthe best HER catalysts with the change of Gibbs free energy {\\Delta}G*H ~ 0 eV,\ncomplying with the thermoneutral condition. The ab initio molecular dynamics\nsimulations reveal that Ti2CF2-PtSA and Ti2CH2O2-PtSA possess a good\nthermodynamic stability. The present work shows that the HER catalytic activity\nof the MXene is not solely governed by the local environment of the surface\nsuch as Pt single atom. We point out the critical role of thickness control and\nsurface decoration of substrate in achieving a high-performance HER catalytical\nactivity.",
        "positive": "$Ab-initio$ investigation of the thermodynamics of cation distribution\n  and the electronic and magnetic structures in the LiMn$_2$O$_4$ spinel: The spinel-structured lithium manganese oxide (LiMn$_2$O$_4$) is a material\ncurrently used as cathode for secondary lithium-ion batteries, but whose\nproperties are not yet fully understood. Here, we report a computational\ninvestigation of the inversion thermodynamics and electronic behaviour of\nLiMn$_2$O$_4$ derived from spin-polarised density functional theory\ncalculations with a Hubbard Hamiltonian and long-range dispersion corrections\n(DFT+$U-$D3). Based on the analysis of the configurational free energy, we have\nelucidated a partially inverse equilibrium cation distribution for the\nLiMn$_2$O$_4$ spinel. This equilibrium degree of inversion is rationalised in\nterms of the crystal field stabilisation effects and the difference between the\nsize of the cations. We compare the atomic charges with the oxidation numbers\nfor each degree of inversion. We found segregation of the Mn charge once these\nions occupy the tetrahedral and octahedral sites of the spinel. We have\nobtained the atomic projections of the electronic band structure and density of\nstates, showing that the normal LiMn$_2$O$_4$ has half-metallic properties,\nwhile the fully inverse spinel is an insulator. This material is in the\nferrimagnetic state for the inverse and partially inverse cation arrangement.\nThe optimised lattice and oxygen parameters, as well as the equilibrium degree\nof inversion, are in agreement with the available experimental data. The\npartially inverse equilibrium degree of inversion is important in the\ninterpretation of the lithium ion migration and surface properties of the\nLiMn$_2$O$_4$ spinel."
    },
    {
        "anchor": "Controlling the domain structure of ferroelectric nanoparticles using\n  tunable shells: The possibility of controlling the domain structure in spherical\nnanoparticles of uniaxial and multiaxial ferroelectrics using a shell with\ntunable dielectric properties is studied in the framework of\nLandau-Ginzburg-Devonshire theory. Finite element modeling and analytical\ncalculations are performed for Sn2P2S6 and BaTiO3 nanoparticles covered with\nhigh-k polymer, temperature dependent isotropic paraelectric strontium\ntitanate, or anisotropic liquid crystal shells with a strongly temperature\ndependent dielectric permittivity tensor. It appeared that the tunable\nparaelectric shell with a temperature dependent high dielectric permittivity\n(~300 - 3000) provides much more efficient screening of the nanoparticle\npolarization than the polymer shell with a much smaller (~10)\ntemperature-independent permittivity. The tunable dielectric anisotropy of the\nliquid crystal shell (~ 1 - 100) adds a new level of functionality for the\ncontrol of ferroelectric domains morphology (including a single-domain state,\ndomain stripes and cylinders, meandering and labyrinthine domains, and\npolarization flux-closure domains and vortexes) in comparison with isotropic\nparaelectric and polymer shells. The obtained results indicate the\nopportunities to control the domain structure morphology of ferroelectric\nnanoparticles covered with tunable shells, which can lead to the generation of\nnew ferroelectric memory and advanced cryptographic materials.",
        "positive": "Identification of the major cause of endemically poor mobilities in\n  SiC/SiO2 structures: Materials with good carrier mobilities are desired for device applications,\nbut in real devices the mobilities are usually limited by the presence of\ninterfaces and contacts. Mobility degradation at semiconductor-dielectric\ninterfaces is generally attributed to defects at the interface or inside the\ndielectric, as is the case in Si/SiO2 structures, where processing does not\nintroduce detrimental defects in the semiconductor. In the case of SiC/SiO2\nstructures, a decade of research focused on reducing or passivating interface\nand oxide defects, but the low mobilities have persisted. By invoking\ntheoretical results and available experimental evidence, we show that thermal\noxidation generates carbon di-interstitial defects inside the semiconductor\nsubstrate and that they are a major cause of the poor mobility in SiC/SiO2\nstructures."
    },
    {
        "anchor": "Conduction Channel Formation and Dissolution Due to Oxygen\n  Thermophoresis/Diffusion in Hafnium Oxide Memristors: Transition metal oxide memristors, or resistive random-access memory (RRAM)\nswitches, are under intense development for storage-class memory because of\ntheir favorable operating power, endurance, speed, and density. Their\ncommercial deployment critically depends on predictive compact models based on\nunderstanding nanoscale physico-chemical forces, which remains elusive and\ncontroversial owing to the difficulties in directly observing atomic motions\nduring resistive switching, Here, using scanning transmission synchrotron x-ray\nspectromicroscopy to study in-situ switching of hafnium oxide memristors, we\ndirectly observed the formation of a localized oxygen-deficiency-derived\nconductive channel surrounded by a low-conductivity ring of excess oxygen.\nSubsequent thermal annealing homogenized the segregated oxygen, resetting the\ncells towards their as-grown resistance state. We show that the formation and\ndissolution of the conduction channel are successfully modeled by radial\nthermophoresis and Fick diffusion of oxygen atoms driven by Joule heating. This\nconfirmation and quantification of two opposing nanoscale radial forces that\naffect bipolar memristor switching are important components for any future\nphysics-based compact model for the electronic switching of these devices.",
        "positive": "FourPhonon: An extension module to ShengBTE for computing four-phonon\n  scattering rates and thermal conductivity: FourPhonon is a computational package that can calculate four-phonon\nscattering rates in crystals. It is built within ShengBTE framework, which is a\nwell-recognized lattice thermal conductivity solver based on Boltzmann\ntransport equation. An adaptive energy broadening scheme is implemented for the\ncalculation of four-phonon scattering rates. In analogy with $thirdorder.py$ in\nShengBTE, we also provide a separate python script, $Fourthorder.py$, to\ncalculate fourth-order interatomic force-constants. The extension module\npreserves all the nice features of the well-recognized lattice thermal\nconductivity solver ShengBTE, including good parallelism and straightforward\nworkflow. In this paper, we discuss the general theory, program design, and\nexample calculations on Si, BAs and $\\mathrm{LiCoO_2}$."
    },
    {
        "anchor": "Discrete dislocation plasticity HELPs understand hydrogen effects in bcc\n  materials: In an attempt to bridge the gap between atomistic and continuum plasticity\nsimulations of hydrogen in iron, we present three dimensional discrete\ndislocation plasticity simulations incorporating the hydrogen elastic stress\nand a hydrogen dependent dislocation mobility law. The hydrogen induced stress\nis incorporated following the formulation derived by Gu and El-Awady (2018)\nwhich here we extend to a finite boundary value problem, a microcantilever\nbeam, via the superposition principle. The hydrogen dependent mobility law is\nbased on first principle calculations by Katzarov et al. (2017) and was found\nto promote dislocation generation and enhance slip planarity at a bulk hydrogen\nconcentration of 0.1 appm; which is typical for bcc materials. The hydrogen\nelastic stress produced the same behaviour, but only when the bulk\nconcentration was extremely high. In a microcantilever, hydrogen was found to\npromote dislocation activity which lowered the flow stress and generated more\npronounced slip steps on the free surfaces. These observations are consistent\nwith the hydrogen enhanced localized plasticity (HELP) mechanism, and it is\nconcluded that both the hydrogen elastic stress and hydrogen increased\ndislocation mobility are viable explanations for HELP. However it is the latter\nthat dominates at the low concentrations typically found in bcc metals.",
        "positive": "Real-time X-ray Monitoring of the Nucleation and Growth of AlN Epitaxial\n  Films on Sapphire (0001): We report the results of x-ray scattering studies of AlN on c-plane sapphire\nduring reactive radiofrequency magnetron sputtering. The sensitivity of in situ\nx-ray measurements allowed us to follow the structural evolution of strain and\nroughness from initial nucleation layers to fullyrelaxed AlN films. A growth\nrate transient was observed, consistent with the initial formation of\nnon-coalesced islands with significant oxygen incorporation from the substrate.\nFollowing island coalescence, a steady state growth rate was seen with a\ncontinuous shift of the c and a lattice parameters towards the relaxed bulk\nvalues as growth progressed, with films reaching a fully relaxed state at\nthicknesses of about 30 nm."
    },
    {
        "anchor": "PES and XAS Study on Electronic Structures of Multiferroic RMnO$_3$\n  (R=Y, Er): Electronic structures of multiferroic RMnO$_3$ (R=Y, Er) have been\ninvestigated by employing photoemission spectroscopy (PES) and x-ray absorption\nspectroscopy (XAS). We have found that Mn ions in RMnO$_3$ are in the trivalent\nhigh-spin state with the total spin of S=2. The occupied Mn ($d_{xz} - d_{yz}$)\nstates lie deep below $\\rm E_F$, while the occupied Mn ($d_{xy} - d_{x^2\n-y^2}$) states overlap very much with the O $2p$ states. It is observed that\nthe PES spectral intensity of Mn 3d states is negligible above the occupied O\n$2p$ bands, suggesting that YMnO$_3$ is likely to be a charge-transfer\ninsulator. The Mn $d_{3z^2 -r^2}$ state is mostly unoccupied in the\nferroelectric phase of YMnO$_3$.",
        "positive": "Reducing the positional modulation of NbO6-octahedra in SrxBa1-xNb2O6 by\n  increasing the Barium content: A single crystal neutron diffraction study at\n  ambient temperature for x=0.61 and x=0.34: We report on the influence of the Barium content on the modulation amplitude\nin SrxBa1-xNb2O6 compounds by comparing Sr0.61Ba0.39Nb2O6 (SBN61) and\nSr0.34Ba0.66Nb2O6 (SBN34). Our single crystal neutron diffraction results\ndemonstrate that the amplitude of the positional modulation of the NbO6\noctahedra is reduced with increasing barium content, indicating that the origin\nof the modulation is the partial occupation of the pentagonal channels by Sr\nand Ba atoms. By increasing the Sr content the bigger Ba atoms are replaced by\nthe smaller Sr atoms, which leads to a larger deformation of the surrounding\nlattice and hence to a larger modulation amplitude. The more homogeneous the\nfilling of these channels with one atomic type (Ba) the lower the modulation\namplitude. Our results also show that the structure can be described with a\ntwo-dimensional incommensurate harmonic modulation. No second order modulation\nhas been observed, both by single crystal diffraction measurements and q-scans.\nThe positional modulation of the Nb atoms is much smaller than that of the\noxygen atoms, such that the modulation can be seen as a rotational modulation\nof almost rigid NbO6-octahedra."
    },
    {
        "anchor": "Disorder and the effective Mn-Mn exchange interaction in\n  Ga$_{1-x}$Mn$_x$As diluted magnetic semiconductors: We perform a theoretical study, using {\\it ab initio} total energy\ndensity-functional calculations, of the effects of disorder on the $Mn-Mn$\nexchange interactions for $Ga_{1-x}Mn_xAs$ diluted semiconductors. For a 128\natoms supercell, we consider a variety of configurations with 2, 3 and 4 Mn\natoms, which correspond to concentrations of 3.1%, 4.7%, and 6.3%,\nrespectively. In this way, the disorder is intrinsically considered in the\ncalculations. Using a Heisenberg Hamiltonian to map the magnetic excitations,\nand {\\it ab initio} total energy calculations, we obtain the effective $\\JMn$,\nfrom first ($n=1$) all the way up to sixth ($n=6$) neighbors. Calculated\nresults show a clear dependence in the magnitudes of the $\\JMn$ with the Mn\nconcentration $x$. Also, configurational disorder and/or clustering effects\nlead to large dispersions in the Mn-Mn exchange interactions, in the case of\nfixed Mn concentration. Moreover, theoretical results for the ground-state\ntotal energies for several configurations indicate the importance of a proper\nconsideration of disorder in treating temperature and annealing effects.",
        "positive": "Strain Induced Relaxor-type Ferroelectricity Near Room Temperature in\n  Delafossite CuCrO2: Polycrystalline samples of CuCrO2 were synthesized by solid state reaction\nmethod. Temperature dependent dielectric measurements, synchrotron x-ray\ndiffraction (SXRD), pyroelectric current and Raman measurements have been\nperformed on these samples. Evidences of the presence of relaxor type\nferroelectricity, which otherwise have gone unnoticed in CuCrO2 system (a\nmember of delafossite family) near room temperature, have been presented.\nPresence of broad maximum in dielectric permittivity and its frequency\ndispersion indicates relaxor-type ferroelectricity in CuCrO2 near room\ntemperature. Careful analysis of temperature dependent SXRD data and Raman\nspectroscopic data indicates that the distorted CrO6 octahdera, is giving rise\nto strain in the sample. Due to this strain, polar regions are forming in an\notherwise non-polar matrix, which is giving rise to relaxor type\nferroelectricity in the sample. Regularization of CrO6 octahedra and\ndisappearance of disorder induced peak in Raman spectra at high temperatures\ncould be the reason behind observed dielectric anomaly in this sample. Present\ninvestigations propose that relaxor type ferroelectricity near room temperature\nis an inherent property of the CuCrO2 system, making it a fascinating material\nto be explored further."
    },
    {
        "anchor": "Band gap and band offset of Ga$_2$O$_3$ and (Al$_x$Ga$_{1-x}$)$_2$O$_3$\n  alloys: Ga$_2$O$_3$ and (Al$_x$Ga$_{1-x}$)$_2$O$_3$ alloys are promising materials\nfor solar-blind UV photodetectors and high-power transistors. Basic key\nparameters in the device design, such as band gap variation with alloy\ncomposition and band offset between Ga$_2$O$_3$ and\n(Al$_x$Ga$_{1-x}$)$_2$O$_3$, are yet to be established. Using density\nfunctional theory with the HSE hybrid functional, we compute formation\nenthalpies, band gaps, and band edge positions of (Al$_x$Ga$_{1-x}$)$_2$O$_3$\nalloys in the monoclinic ($\\beta$) and corundum ($\\alpha$) phases. We find the\nformation enthlapies of (Al$_x$Ga$_{1-x}$)$_2$O$_3$ alloys are significantly\nlower than of (In$_x$Ga$_{1-x}$)$_2$O$_3$, and that (Al$_x$Ga$_{1-x}$)$_2$O$_3$\nwith $x$=0.5 can be considered as an ordered compound AlGaO$_3$ in the\nmonoclinic phase, with Al occupying the octahedral sites and Ga occupying the\ntetrahedral sites. The direct band gaps of the alloys range from 4.69 to 7.03\neV for $\\beta$-(Al$_x$Ga$_{1-x}$)$_2$O$_3$ and from 5.26 to 8.56 eV for\n$\\alpha$-(Al$_x$Ga$_{1-x}$)$_2$O$_3$. Most of the band offset of the\n(Al$_x$Ga$_{1-x}$)$_2$O$_3$ alloy arises from the discontinuity in the\nconduction band. Our results are used to explain the available experimental\ndata, and consequences for designing modulation-doped field effect transistors\n(MODFETs) based on (Al$_x$Ga$_{1-x}$)$_2$O$_3$/Ga$_2$O$_3$ are discussed.",
        "positive": "Bi-continuum modelling of layered structures and crystalline interfaces: The bi-continuum model composed of two interpenetrating and dynamically\ncoupled material continua is analysed as a simplified but relatively accurate\nway to describe some physical phenomena in crystalline solids. The essential\nnovelty of our approach consists in treating a crystalline medium as\nbi-continuum, even if the crystalline lattice is structurally single-component.\nParticular attention is paid to the oscillatory behaviour of solutions on the\natomic level. Starting from a discrete atomic chain, the basic formulation of\nthe bi-continuum model is derived. The essential features of the model,\nincluding accuracy of the results as functions of physical parameters, are\ndiscussed."
    },
    {
        "anchor": "Non-collinear Spin Valve Effect in Ferromagnetic Semiconductor Trilayers: We report the observation of the spin valve effect in\n(Ga,Mn)As/p-GaAs/(Ga,Mn)As trilayer devices. Magnetoresistance measurements\ncarried out in the current in plane geometry reveal positive magnetoresistance\npeaks when the two ferromagnetic layers are magnetized orthogonal to each\nother. Measurements carried out for different post-growth annealing conditions\nand spacer layer thickness suggest that the positive magnetoresistance peaks\noriginate in a noncollinear spin valve effect due to spin-dependent scattering\nthat is believed to occur primarily at interfaces.",
        "positive": "High magnetoresistance of hexagonal boron nitride-graphene\n  heterostructure-based MTJ through excited-electron transmission: This work presents an ab-initio study of a few-layers hexagonal boron nitride\n(hBN) and hBN-graphene heterostructure sandwiched between Ni(111) layers. The\naim of this study is to understand the electron transmission process through\nthe interface. Spin-polarized density functional theory calculations and\ntransmission probability calculations were conducted on Ni(111)/$n$hBN/Ni(111)\nwith $n$ = 2, 3, 4, and 5 as well as on Ni(111)/hBN-Gr-hBN/Ni(111). Slabs with\nmagnetic alignment in an anti-parallel configuration (APC) and parallel\nconfiguration (PC) were considered. The pd-hybridizations at both the upper and\nlower interfaces between the Ni slabs and hBN were found to stabilize the\nsystem. The Ni/nhBN/Ni magnetic tunnel junction (MTJ) was found to exhibit a\nhigh tunneling magnetoresistance (TMR) ratio at ~0.28 eV for $n$ = 2 and 0.34\neV for $n$ > 2, which are slightly higher than the Fermi energy. The observed\nshifting of this high TMR ratio originates from the transmission of electrons\nthrough the surface states of the $d_{z^2}$-orbital of Ni atoms at interfaces\nwhich are hybridized with the $p_z$-orbital of N atoms. In the case of $n$ > 2,\nthe proximity effect causes an evanescent wave, contributing to decreasing\ntransmission probability but increasing the TMR ratio. However, TMR ratio, as\nwell as transmission probability, was found to be increased, by replacing the\nunhybridized hBN layer of the Ni/3hBN/Ni MTJ with graphene, thus becoming\nNi/hBN-Gr-hBN/Ni. A TMR ratio as high as ~1200% was observed at an energy of\n0.34 eV, which is higher than the Fermi energy. Furthermore, a design is\nproposed for a device based on a new reading mechanism using the high TMR\nobserved just above the Fermi energy level."
    },
    {
        "anchor": "Alloy Stabilized Wurtzite Ground State Structures of Zinc-Blende\n  Semiconducting Compounds: The ground state structures of the A$_x$B$_{1-x}$C wurtzite (WZ) alloys with\n$x=$0.25, 0.5, and 0.75 are revealed by a ground state search using the\nvalence-force field model and density-functional theory total energy\ncalculations. It is shown that the ground state WZ alloy always has a lower\nstrain energy and formation enthalpy than the corresponding zinc-blende (ZB)\nalloy. Therefore, we propose that the WZ phase can be stabilized through\nalloying. This novel idea is supported by the fact that the WZ\nAlP$_{0.5}$Sb$_{0.5}$, AlP$_{0.75}$Sb$_{0.25}$, ZnS$_{0.5}$Te$_{0.5}$, and\nZnS$_{0.75}$Te$_{0.25}$ alloys in the lowest energy structures are more stable\nthan the corresponding ZB alloys. To our best knowledge, this is the first\nexample where the alloy adopts a structure distinct from both parent phases.",
        "positive": "Rapid CVD growth of millimetre-sized single crystal graphene using a\n  cold-wall reactor: In this work we present a simple pathway to obtain large single-crystal\ngraphene on copper (Cu) foils with high growth rates using a commercially\navailable cold-wall chemical vapour deposition (CVD) reactor. We show that\ngraphene nucleation density is drastically reduced and crystal growth is\naccelerated when: i) using ex-situ oxidised foils; ii) performing annealing in\nan inert atmosphere prior to growth; iii) enclosing the foils to lower the\nprecursor impingement flux during growth. Growth rates as high as 14.7 and 17.5\nmicrometers per minute are obtained on flat and folded foils, respectively.\nThus, single-crystal grains with lateral size of about one millimetre can be\nobtained in just one hour. The samples are characterised by optical microscopy,\nscanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS),\nRaman spectroscopy as well as selected area electron diffraction (SAED) and\nlow-energy electron diffraction (LEED), which confirm the high quality and\nhomogeneity of the films. The development of a process for the quick production\nof large grain graphene in a commonly used commercial CVD reactor is a\nsignificant step towards an increased accessibility to millimetre-sized\ngraphene crystals."
    },
    {
        "anchor": "Femtosecond time-resolved dynamical Franz-Keldysh effect: We theoretically investigate the dynamical Franz-Keldysh effect in\nfemtosecond time resolution, that is, the time-dependent modulation of a\ndielectric function at around the band gap under an irradiation of an intense\nlaser field. We develop a pump-probe formalism in two distinct approaches:\nfirst-principles simulation based on real-time time-dependent density\nfunctional theory and analytic consideration of a simple two-band model. We\nfind that, while time-average modulation may be reasonably described by the\nstatic Franz-Keldysh theory, a remarkable phase shift is found to appear\nbetween the dielectric response and the applied electric field.",
        "positive": "Phase-field modeling of the discontinuous precipitation reaction: A multi-phase-field model for the description of the discontinuous\nprecipitation reaction is formulated which takes into account surface diffusion\nalong grain boundaries and interfaces as well as volume diffusion. Simulations\nreveal that the structure and steady-state growth velocity of spatially\nperiodic precipitation fronts strongly depend on the relative magnitudes of the\ndiffusion coefficients. Steady-state solutions always exist for a range of\ninterlamellar spacings that is limited by a fold singularity for low spacings,\nand by the onset of tip-splitting or oscillatory instabilities for large\nspacings. A detailed analysis of the simulation data reveals that the\nhypothesis of local equilibrium at interfaces, used in previous theories, is\nnot valid for the typical conditions of discontinuous precipitation."
    },
    {
        "anchor": "Uncovering the lowest thickness limit for room-temperature\n  ferromagnetism of Cr$_{1.6}$Te$_{2}$: Half-metallic ferromagnetic transition metal dichalcogenides have emerged as\nimportant building blocks for scalable magnonics and memory applications.\nDownscaling such systems to the ultra-thin limit is critical to integrate them\ninto technology. Here, we achieved layer-by-layer control over the transition\nmetal dichalcogenide Cr$_{1.6}$Te$_{2}$ by using pulsed laser deposition, and\nwe uncovered the minimum critical thickness above which room temperature\nmagnetic order is maintained. The electronic and magnetic structure is explored\nexperimentally and theoretically and it is shown that the films exhibit strong\nin-plane magnetic anisotropy as a consequence of large spin-orbit effects. Our\nstudy establishes Cr$_{1.6}$Te$_{2}$ as a platform material, viable for\nferromagnetic nanoscale devices and magnetic-memory architectures.",
        "positive": "Double hysteresis loops in proper uniaxial ferroelectrics: For the first time in a bulk proper uniaxial ferroelectrics, double\nantiferroelectric-like hysteresis loops have been observed in the case of\nSn$_2$P$_2$S$_6$ crystal. The quantum anharmonic oscillator model was proposed\nfor description of such polarization switching process. This phenomenon is\nrelated to three-well local potential of spontaneous polarization fluctuations\nat peculiar negative ratio of coupling constants which correspond to inter-site\ninteraction in given sublattice and interaction between two sublattices of\nSn$_2$P$_2$S$_6$ modeled crystal structure. Obtained data can be used for\ndevelopment of triple-level cell type memory technology."
    },
    {
        "anchor": "Fermi level depinning via insertion of a graphene buffer layer at the\n  gold-2D tin monoxide contact: Two-dimensional (2D) tin monoxide (SnO) has attracted much attention owing to\nits distinctive electronic and optical properties, which render itself suitable\nas a channel material in field effect transistors (FETs). However, upon contact\nwith metals for such applications, the Fermi level pinning effect may occur,\nwhere states are induced in its band gap by the metal, hindering its intrinsic\nsemiconducting properties. We propose the insertion of graphene at the contact\ninterface to alleviate the metal-induced gap states. By using gold (Au) as the\nelectrode material and monolayer SnO (mSnO) as the channel material, the\ngeometry, bonding strength, charge transfer and tunnel barriers of charges, and\nelectronic properties including the work function, band structure, density of\nstates, and Schottky barriers are thoroughly investigated using\nfirst-principles calculations for the structures with and without graphene to\nreveal the contact behaviours and Fermi level depinning mechanism. It has been\ndemonstrated that strong covalent bonding is formed between gold and mSnO,\nwhile the graphene interlayer forms weak van der Waals interaction with both\nmaterials, which minimises the perturbance to the band structure of mSnO. The\neffects of out-of-plane compression are also analysed to assess the performance\nof the contact under mechanical deformation, and a feasible fabrication route\nfor the heterostructure with graphene is proposed. This work systematically\nexplores the properties of the Au-mSnO contact for applications in FETs and\nprovides thorough guidance for future exploitation of 2D materials in various\nelectronic applications and for selection of buffer layers to improve\nmetal-semiconductor contact.",
        "positive": "Microscopic elasticity of complex systems: Lecture Notes for the Erice Summer School 2005 Computer Simulations in\nCondensed Matter: from Materials to Chemical Biology. Perspectives in\ncelebration of the 65th Birthday of Mike Klein organized by Kurt Binder,\nGiovanni Ciccotti and Mauro Ferrario"
    },
    {
        "anchor": "Bulk Cr tips for scanning tunneling microscopy and spin-polarized\n  scanning tunneling microscopy: A simple, reliable method for preparation of bulk Cr tips for Scanning\nTunneling Microscopy (STM) is proposed and its potentialities in performing\nhigh-quality and high-resolution STM and Spin Polarized-STM (SP-STM) are\ninvestigated. Cr tips show atomic resolution on ordered surfaces. Contrary to\nwhat happens with conventional W tips, rest atoms of the Si(111)-7x7\nreconstruction can be routinely observed, probably due to a different\nelectronic structure of the tip apex. SP-STM measurements of the Cr(001)\nsurface showing magnetic contrast are reported. Our results reveal that the\npeculiar properties of these tips can be suited in a number of STM experimental\nsituations.",
        "positive": "New Gd-based magnetic compound GdPt$_2$B with a chiral crystal structure: Herein, we report the discovery of a novel Gd-based magnetic compound\nGdPt$_2$B with a chiral crystal structure. X-ray diffraction and chemical\ncomposition analyses reveal a CePt$_2$B-type crystal structure (space group:\n$P6_422$) for GdPt$_2$B. Moreover, we successfully grew single crystals of\nGdPt$_2$B using the Czochralski method. Magnetization measurements and the\nCurie$-$Weiss analysis demonstrate that the ferromagnetic interaction is\ndominant in GdPt$_2$B. A clear transition is observed in the temperature\ndependence of electrical resistivity, magnetic susceptibility, and specific\nheat at $T_{\\rm O}$ = 87 K. The magnetic phase diagram of GdPt$_2$B, which\nconsists of a field-polarized ferromagnetic region and a magnetically ordered\nregion, resembles those of known chiral helimagnets. Furthermore, magnetic\nsusceptibility measurements reveal a possible spin reorientation within the\nmagnetically ordered phase in magnetic fields perpendicular to the screw axis.\nThe results demonstrate that GdPt$_2$B is a suitable platform for investigating\nthe competing effects of ferromagnetic and antisymmetric exchange interactions\nin rare-earth-based chiral compounds."
    },
    {
        "anchor": "Strain enhancement of high-k dielectric response in (La/Sc)2 O3 and\n  LaScO3 : an ab-initio study: We use density functional theory within the generalized gradient\napproximation to characterize the dielectric response of rare earth oxides:\n(La,Sc)2 O3 bixbyite, and LaScO3 perovskite. We focus on the role of strain on\nthe phonon contribution of the dielectric constant and find that, contrary to\nthe classical expectation based on the Clausius-Mossotti relation, tensile\nvolumetric strain and volume-conserving bi- axial strain on the order of +/-1%\ncan lead to an increase in dielectric constant of up to 20%. The insight into\nthe atomic mechanisms responsible for these effects and the quantitative\nresults in this paper can contribute to the development and understanding of\nhigh-{\\kappa} materials.",
        "positive": "Optical spectra of 2D monolayers from time-dependent density functional\n  theory: The optical spectra of two-dimensional (2D) periodic systems provide a\nchallenge for time-dependent density-functional theory (TDDFT) because of the\nlarge excitonic effects in these materials. In this work we explore how\naccurately these spectra can be described within a pure Kohn-Sham\ntime-dependent density-functional framework, i.e., a framework in which no\ntheory beyond Kohn-Sham density-functional theory, such as $GW$, is required to\ncorrect the Kohn-Sham gap. To achieve this goal we adapted a recent approach we\ndeveloped for the optical spectra of 3D systems [Cavo, Berger, Romaniello,\nPhys. Rev. B 101, 115109 (2020)] to those of 2D systems. Our approach relies on\nthe link between the exchange-correlation kernel of TDDFT and the derivative\ndiscontinuity of ground-state density-functional theory, which guarantees a\ncorrect quasi-particle gap, and on a generalization of the polarization\nfunctional [Berger, Phys. Rev. Lett., 115, 137402 (2015)], which describes the\nexcitonic effects. We applied our approach to two prototypical 2D monolayers,\n$h$-BN and MoS$_2$. We find that our protocol gives a qualitative good\ndescription of the optical spectrum of $h$-BN, whereas improvements are needed\nfor MoS$_2$ to describe the intensity of the excitonic peaks."
    },
    {
        "anchor": "On the mechanism of hydrophilicity of graphene: It is generally accepted that the hydrophilic property of graphene can be\naffected by the underlying substrate. However, the role of intrinsic vs.\nsubstrate contributions and the related mechanisms are vividly debated. Here we\nshow that the intrinsic hydrophilicity of graphene can be intimately connected\nto the position of its Fermi level, which affects the interaction between\ngraphene and water molecules. The underlying substrate, or dopants, can tune\nhydrophilicity by modulating the Fermi level of graphene. By shifting the Fermi\nlevel of graphene away from its Dirac point, via either chemical or electrical\nvoltage doping, we show enhanced hydrophilicity with experiments and first\nprinciple simulations. Increased vapor condensation on graphene, induced by a\nsimple shifting of its Fermi level, exemplifies applications in the area of\ninterfacial transport phenomena.",
        "positive": "Thermoelectrics: from Longitudinal to Transverse: In this article, we show fundamentals and recent advances on the transverse\nthermoelectric generation, in which a thermopower is generated in the direction\nperpendicular to an applied temperature gradient. Transverse thermoelectric\ngeneration is one of the central topics in condensed matter physics, and can be\na breakthrough approach to solve long-standing technological problems with\ncontact resistances in thermoelectric generators. We review here the six\ncurrently known driving mechanisms: the ordinary Nernst effect, the anomalous\nNernst effect, goniopolar materials, the spin Seebeck effect, Seebeck-driven\ntransverse thermoelectric generation, and ($p \\times n$)-type multilayers. This\narticle summarizes the principles and functionalities of these transverse\nthermoelectric effects and discusses their potential as \"Future energy\"."
    },
    {
        "anchor": "Strain-induced enhancement of the Seebeck effect in magnetic tunneling\n  junctions via interface resonant tunneling: Ab-initio study: We investigate the thermoelectric properties of Fe/MgO/Fe(001) magnetic\ntunnel junctions (MTJs) by means of the linear-response theory combined with a\nfirst-principles-based Landauer-B\\\"uttiker approach. We find that the Seebeck\ncoefficient of Fe/MgO/Fe(001) MTJs strongly depends on the barrier thickness\nand the tetragonal distortion. A compressive tetragonal distortion of the\nin-plane lattice parameter in the MTJs provides interface resonant states just\nabove the Fermi energy. This causes resonant tunneling in the MTJs and\nsignificantly enhances the Seebeck coefficient when the thickness of the MgO\nbarrier is around 1 nm (four or five atomic layers of MgO). Moreover, an\nextensive tetragonal distortion of the in-plane lattice parameter pushes the\ninterface states away from the Fermi energy, leading to a reduction of the\nSeebeck coefficient. Furthermore, we find that the interface resonant tunneling\nenhances the power factor of the MTJs for the compressive distortion. These\nresults indicate that control of the barrier thickness and the tetragonal\ndistortion will be effective for maximizing the thermoelectric properties of\nMTJs.",
        "positive": "Correlation between magnetic interactions and domain structure in A1\n  FePt ferromagnetic thin films: We have investigated the relationship between the domain structure and the\nmagnetic interactions in a series of FePt ferromagnetic thin films of varying\nthickness. As-made films grow in the magnetically soft and chemically\ndisordered A1 phase that may have two distinct domain structures. Above a\ncritical thickness $d_{cr}\\sim 30$ nm the presence of an out of plane\nanisotropy induces the formation of stripes, while for $d<d_{cr}$ planar\ndomains occur.\n  Magnetic interactions have been characterized using the well known DCD-IRM\nremanence protocols, $\\delta M$ plots, and magnetic viscosity measurements. We\nhave observed a strong correlation between the domain configuration and the\nsign of the magnetic interactions. Planar domains are associated with positive\nexchange-like interactions, while stripe domains have a strong negative\ndipolar-like contribution. In this last case we have found a close correlation\nbetween the interaction parameter and the surface dipolar energy of the stripe\ndomain structure. Using time dependent magnetic viscosity measurements, we have\nalso estimated an average activation volume for magnetic reversal, $\\langle\nV_{ac}\\rangle \\sim 1.37\\times 10^{4}$ nm$^{3},$ which is approximately\nindependent of the film thickness or the stripe period."
    },
    {
        "anchor": "Titanium oxynitride thin films with tunable double epsilon-near-zero\n  behaviour: Titanium Oxynitride (TiOxNy) thin films are fabricated using reactive\nmagnetron sputtering. The mechanism of their growth formation is explained and\ntheir optical properties are presented. The films grown when the level of\nresidual Oxygen in the background vacuum was between 5E-9Torr to 20E-9Torr\nexhibit double Epsilon-Near-Zero (2-ENZ) behaviour with ENZ1 and ENZ2\nwavelengths tunable in the 700-850 nm and in the 1100-1350 nm spectral ranges,\nrespectively. Samples fabricated when the level of residual Oxygen in the\nbackground vacuum was above 2E-8Torr exhibit non-metallic behaviour, while the\nlayers deposited when the level of residual Oxygen in the background vacuum was\nbelow 5E-9Torr, show metallic behaviour with a single ENZ value. The double ENZ\nphenomenon is related to the level of residual Oxygen in the background vacuum\nand is attributed to the mixture of TiN and TiOxNy/TiOx phases in the films.\nVarying the partial pressure of nitrogen during the deposition can further\ncontrol the amount of TiN, TiOx and TiOxNy compounds in the films and,\ntherefore, tune the screened plasma wavelength. A good approximation of the\nellipsometric behaviour is achieved with Maxwell-Garnett theory for a composite\nfilm formed by a mixture of TiO2 and TiN phases suggesting that double ENZ\nTiOxNy films are formed by inclusions of TiN within a TiO2 matrix. These\noxynitride compounds could be considered as new materials exhibiting double ENZ\nin the visible and near-IR spectral ranges.",
        "positive": "Unsupervised segmentation of irradiation$\\unicode{x2010}$induced\n  order$\\unicode{x2010}$disorder phase transitions in electron microscopy: We present a method for the unsupervised segmentation of electron microscopy\nimages, which are powerful descriptors of materials and chemical systems.\nImages are oversegmented into overlapping chips, and similarity graphs are\ngenerated from embeddings extracted from a domain$\\unicode{x2010}$pretrained\nconvolutional neural network (CNN). The Louvain method for community detection\nis then applied to perform segmentation. The graph representation provides an\nintuitive way of presenting the relationship between chips and communities. We\ndemonstrate our method to track irradiation$\\unicode{x2010}$induced amorphous\nfronts in thin films used for catalysis and electronics. This method has\npotential for \"on$\\unicode{x2010}$the$\\unicode{x2010}$fly\" segmentation to\nguide emerging automated electron microscopes."
    },
    {
        "anchor": "High-Symmetry Polarization Domains in Low-Symmetry Ferroelectrics: We present experimental evidence for hexagonal domain faceting in the\nferroelectric polymer PVDF-TrFE films having the lower orthorhombic\ncrystallographic symmetry. This effect can arise from purely electrostatic\ndepolarizing forces. We show that in contrast to magnetic bubble shape domains\nwhere such type of deformation instability has a predominantly elliptical\ncharacter, the emergence of more symmetrical circular harmonics is favored in\nferroelectrics with high dielectric constant.",
        "positive": "The third-order elastic moduli and pressure derivatives for AlRE (RE=Y,\n  Pr, Nd, Tb, Dy, Ce) intermetallics with B2-structure: A first-principles\n  study: The third-order elastic moduli and pressure derivatives of the second-order\nelastic constants of novel B2-type AlRE (RE=Y, Pr, Nd, Tb, Dy, Ce)\nintermetallics are presented from first-principles calculations. The elastic\nmoduli are obtained from the coefficients of the polynomials from the nonlinear\nleast-squares fitting of the energy-strain functions. The calculated\nsecond-order elastic constants of AlRE intermetallics are consistent with the\nprevious calculations. To judge that our computational accuracy is reasonable,\nthe calculated third-order constants of Al are compared with the available\nexperimental data and other theoretical results and found very good agreement.\nIn comparison with the theory of the linear elasticity, the third-order effects\nare very important with the finite strains are lager than approximately 3.5%.\nFinally, the pressure derivative has been discussed."
    },
    {
        "anchor": "Composition Susceptibility and the Role of One, Two and Three Body\n  Interactions in Glass Forming Alloys: Cu$_{50}$Zr$_{50}$ vs\n  Ni$_{50}$Al$_{50}$: In this paper we compare the composition fluctuations and interaction\npotentials of a good metallic glass former, Cu$_{50}$Zr$_{50}$, and a poor\nglass former, Ni$_{50}$Al$_{50}$. The Bhatia-Thornton correlations functions\nare calculated. Inspired by the observation of chemical ordering at the NiAl\nsurface, we derive a new property, R$_{cn}$( q ), corresponding to linear\nsusceptibility of concentration to a perturbation in density. We present a\ndirect comparison of the potentials for the two model alloys, using a 2nd order\ndensity expansion, establish that the one body energy plays a crucial role in\nstabilizing the crystal relative to the liquid in both alloys but that the\nthree body contribution to the heat of fusion is significantly larger in NiAl\nthat CuZr.",
        "positive": "Drift of Charge Carriers in Crystalline Organic Semiconductors: We investigate the direct-current response of crystalline organic\nsemiconductors in the presence of finite external electric fields by the\nquantum-classical Ehrenfest dynamics complemented with instantaneous\ndecoherence corrections (IDC). The IDC is carried out in the real-space\nrepresentation with the energy-dependent reweighing factors to account for both\nintermolecular decoherence and energy relaxation by which conduction occurs. In\nthis way, both the diffusion and drift motion of charge carriers are described\nin a unified framework. Based on an off-diagonal electron-phonon coupling model\nfor pentacene, we find that the drift velocity initially increases with the\nelectric field and then decreases at higher fields due to the Wannier-Stark\nlocalization, and a negative electric-field dependence of mobility is observed.\nThe Einstein relation, which is a manifestation of the fluctuation-dissipation\ntheorem, is found to be restored in electric fields up to ~$10^5$ V/cm for a\nwide temperature region studied. Furthermore, we show that the incorporated\ndecoherence and energy relaxation could explain the large discrepancy between\nthe mobilities calculated by the Ehrenfest dynamics and the full quantum\nmethods, which proves the effectiveness of our approach to take back these\nmissing processes."
    },
    {
        "anchor": "Explicit expression for Lindhard dielectric function at finite\n  temperature: In this work, within the scope of the Lindhard dielectric function formalism\nfor the homogeneous electron gas, explicit expressions for the real and\nimaginary parts are calculated for finite temperature. An application to Raman\nscattering in n-type GaAs is presented to highlight the power of the method",
        "positive": "Photo-response of the conductivity in functionalized pentacene compounds: We report the first investigation of the photo-response of the conductivity\nof a new class of organic semiconductors based on functionalized pentacene.\nThese materials form high quality single crystals that exhibit a thermally\nactivated resistivity. Unlike pure pentacene, the functionalized derivatives\nare readily soluble in acetone, and can be evaporated or spin-cast as thin\nfilms for potential device applications. The electrical conductivity of the\nsingle crystal materials is noticeably sensitive to ambient light changes. The\npurpose, therefore, of the present study, is to determine the nature of the\nphoto-response in terms of carrier activation vs. heating effects, and also to\nmeasure the dependence of the photo-response on photon energy. We describe a\nnew method, involving the temperature dependent photo-response, which allows an\nunambiguous identification of the signature of heating effects in materials\nwith a thermally activated conductivity. We find strong evidence that the\nphoto-response in the materials investigated is predominantly a highly\nlocalized heating mechanism. Wavelength dependent studies of the photo-response\nreveal resonant features and cut-offs that indicate the photon energy\nabsorption is related to the electronic structure of the material."
    },
    {
        "anchor": "Lithium transport through Lithium-ion battery cathode coatings: The surface coating of cathodes using insulator films has proven to be a\npromising method for high-voltage cathode stabilization in Li-ion batteries.\nHowever, there is still substantial uncertainty about how these films function,\nspecifically with regard to important coating design principles such as lithium\nsolubility and transport through the films. This study uses Density Functional\nTheory to examine the diffusivity of interstitial lithium in crystalline\n{\\alpha}-$AlF_3$, {\\alpha}-$Al_2O_3$, m-$ZrO_2$, c-MgO, and {\\alpha}-quartz\n$SiO_2$, which provide benchmark cases for further understanding of insulator\ncoatings in general. In addition, we propose an Ohmic electrolyte model to\npredict resistivities and overpotential contributions under battery operating\nconditions. For the crystalline materials considered we predict that Li+\ndiffuses quite slowly, with a migration barrier larger than 0.9 eV in all\ncrystalline materials except {\\alpha}-quartz $SiO_2$, which is predicted to\nhave a migration barrier of 0.276 eV along <001>. These results suggest that\nthe stable crystalline forms of these insulator materials, except for oriented\n{\\alpha}-quartz $SiO_2$, are not practical for conformal cathode coatings.\nAmorphous $Al_2O_3$ and $AlF_3$ have higher Li+ diffusivities than their\ncrystalline counterparts. Our predicted amorphous $Al_2O_3$ resistivity (1789\nM{\\Omega}m) is near the top of the range of fitted resistivities extracted from\nprevious experiments on nominal $Al_2O_3$ coatings (7.8 to 913 M{\\Omega}m)\nwhile our predicted amorphous $AlF_3$ resistivity (114 M{\\Omega}m) is close to\nthe middle of the range. These comparisons support our framework for modeling\nand understanding the impact on overpotential of conformal coatings in terms of\ntheir fundamental thermodynamic and kinetic properties, and support that these\nmaterials can provide practical conformal coatings in their amorphous form.",
        "positive": "Molecular Dynamics Study of the Primary Ferrofluid Aggregate Formation: Investigations of the phase transitions and self-organization in the magnetic\naggregates are of the fundamental and applied interest. The long-range ordering\nstructures described in the Tom\\'anek's systematization (M. Yoon, and D.\nTom\\'anek, 2010 [1]) are not yet obtained in the direct molecular dynamics\nsimulations. The resulted structures usually are the linear chains or circles,\nor, else, amorphous (liquid) formations. In the present work, it was shown,\nthat the thermodynamically equilibrium primary ferrofluid aggregate has either\nthe long-range ordered or liquid phase. Due to the unknown steric layer force\nand other model idealizations, the clear experimental verification of the real\nequilibrium phase is still required. The predicted long-range ordered\n(crystallized) phase produces the faceting shape of the primary ferrofluid\naggregate, which can be recognized experimentally. The medical (antiviral)\napplication of the crystallized aggregates has been suggested. Dynamic\nformation of all observed ferrofluid nanostructures conforms to the Tom\\'anek's\nsystematization."
    },
    {
        "anchor": "A first-principles investigation of the structural and electrochemical\n  properties of biredox ionic species in acetonitrile: Biredox ionic liquids are a new class of functionalized electrolytes that may\nplay an important role in future capacitive energy storage devices. By allowing\nadditional storage of electrons inside the liquids, they can improve device\nperformance significantly. However current devices employ nanoporous carbons in\nwhich the diffusion of the liquid and the adsorption of the ions could be\naffected by the occurrence of electron-transfer reactions. It is therefore\nnecessary to understand better the thermodynamics and the kinetics of such\nreactions in biredox ionic liquids. Here we perform ab initio molecular\ndynamics simulations of both the oxidized and reduced species of several\nredox-active ionic molecules (used in biredox ionic liquids) dissolved in\nacetonitrile solvent and compare them with the bare redox molecules. We show\nthat in all the cases, it is necessary to introduce a two Gaussian state model\nto calculate the reaction free energies accurately. These reaction free\nenergies are only slightly affected by the presence of the IL group on the\nmolecule. We characterize the structure of the solvation shell around the redox\nactive part of the molecules and show that in the case of TEMPO-based molecules\nstrong reorientation effects occur during the oxidation reaction.",
        "positive": "Structural and magnetic properties of Cr-diluted CoFeB: The crystallization process and the magnetization of Cr diluted CoFeB was\ninvestigated in both ribbon samples and thin film samples with Cr content up to\n30 at. %. A primary crystallization of bcc phase from an amorphous precursor in\nribbon samples was observed when the annealing temperature rose to between 421\noC and 456 oC, followed by boron segregation at temperatures between 518 oC and\n573 oC. The two onset crystallization temperatures showed strong dependences on\nboth Cr and B concentrations. The impact of Cr concentration on the magnetic\nproperties including a reduced saturation magnetization and an enhanced\ncoercive field was also observed. The magnetizations of both ribbon samples and\nthin film samples were well fitted using the generalized Slater-Pauling curve\nwith modified moments for B (-0.94 {\\mu}B) and Cr (-3.6 {\\mu}B). Possible\norigins of the enhanced coercive field were also discussed. We also achieved a\ndamping parameter in CoFeCrB thin films at the same level as Co40Fe40B20, much\nlower than the value reported for CoFeCrB films previously. The results suggest\na possible advantage of CoFeCrB in reducing the critical switching current\ndensity in Spin Transfer Torque Random Access Memory (STT-RAM)."
    },
    {
        "anchor": "High thermoelectric performance can be achieved in black phosphorus: Few-layer black phosphorus has recently emerged as a promising candidate for\nnovel electronic and optoelectronic device. Here we demonstrate by\nfirst-principles calculations and Boltzmann theory that, black phosphorus could\nalso have potential thermoelectric applications and a fair ZT value of 1.1 can\nbe achieved at elevated temperature. Moreover, such value can be further\nincreased to 5.4 by substituting P atom with Sb atom, giving nominal formula of\nP0.75Sb0.25. Our theoretical work suggests that high thermoelectric performance\ncan be achieved without using complicated crystal structure or seeking for\nlow-dimensional systems.",
        "positive": "Temporally-decoherent and spatially-coherent vibrations in metal halide\n  perovskite: The long carrier lifetime and defect tolerance in metal halide perovskites\n(MHPs) are major contributors to the superb performance of MHP optoelectronic\ndevices. Large polarons were reported to be responsible for the long carrier\nlifetime. Yet microscopic mechanisms of the large polaron formation including\nthe so-called phonon melting, are still under debate. Here, time-of-flight\n(TOF) inelastic neutron scattering (INS) experiments and first-principles\ndensity-functional theory (DFT) calculations were employed to investigate the\nlattice vibrations (or phonon dynamics) in methylammonium lead iodide\n($\\rm{MAPbI_3}$), a prototypical example of MHPs. Our findings are that optical\nphonons lose temporal coherence gradually with increasing temperature which\nvanishes at the orthorhombic-to-tetragonal structural phase transition.\nSurprisingly, however, we found that the spatial coherence is still retained\nthroughout the decoherence process. We argue that the temporally decoherent and\nspatially coherent vibrations contribute to the formation of large polarons in\nthis metal halide perovskite."
    },
    {
        "anchor": "Non-linear generalized elasticity of icosahedral quasicrystals: Quasicrystals can carry, in addition to the classical phonon displacement\nfield, a phason displacement field, which requires a generalized theory of\nelasticity. In this paper, the third-order strain invariants (including phason\nstrain) of icosahedral quasicrystals are determined. They are connected with 20\nindependent third-order elastic constants. By means of non-linear elasticity,\nphason strains with icosahedral irreducible Gamma^4-symmetry can be obtained by\nphonon stress, which is impossible in linear elasticity.",
        "positive": "Lattice dynamics in magnetic superelastic Ni-Mn-In alloys. Neutron\n  scattering and ultrasonic experiments: Neutron scattering and ultrasonic methods have been used to study the lattice\ndynamics of two single crystals of Ni-Mn-In Heusler alloys close to\nNi$_{50}$Mn$_{34}$In$_{16}$ magnetic superelastic composition. The paper\nreports the experimental determination of the low-lying phonon dispersion\ncurves and the elastic constants for this alloy system. We found that the\nfrequencies of the TA$_{2}$ branch are relatively low and it exhibits a small\ndip anomaly at a wave number $\\xi_{0} \\approx 1/3$, which softens with\ndecreasing temperature. Associated with the softening of this phonon, we also\nobserved the softening of the shear elastic constant $C'=(C_{11}-C_{12})/2$.\nBoth temperature softenings are typical for bcc based solids which undergo\nmartensitic transformations and reflect the dynamical instability of the cubic\nlattice against shearing of $\\{110\\}$ planes along $<1\\bar{1}0>$ directions.\nAdditionally, we measured low-lying phonon dispersion branches and elastic\nconstants in applied magnetic fields aimed to characterize the magnetoelastic\ncoupling."
    },
    {
        "anchor": "First-principles prediction of redox potentials in transition-metal\n  compounds with LDA+U: First-principles calculations within the Local Density Approximation (LDA) or\nGeneralized Gradient Approximation (GGA), though very successful, are known to\nunderestimate redox potentials, such as those at which lithium intercalates in\ntransition metal compounds. We argue that this inaccuracy is related to the\nlack of cancellation of electron self-interaction errors in LDA/GGA and can be\nimproved by using the DFT+$U$ method with a self-consistent evaluation of the\n$U$ parameter. We show that, using this approach, the experimental lithium\nintercalation voltages of a number of transition metal compounds, including the\nolivine Li$_{x}$MPO$_{4}$ (M=Mn, Fe Co, Ni), layered Li$_{x}$MO$_{2}$ ($x=$Co,\nNi) and spinel-like Li$_{x}$M$_{2}$O$_{4}$ (M=Mn, Co), can be reproduced\naccurately.",
        "positive": "Iron under Earth's core conditions: Liquid-state thermodynamics and\n  high-pressure melting curve: {\\em Ab initio} techniques based on density functional theory in the\nprojector-augmented-wave implementation are used to calculate the free energy\nand a range of other thermodynamic properties of liquid iron at high pressures\nand temperatures relevant to the Earth's core. The {\\em ab initio} free energy\nis obtained by using thermodynamic integration to calculate the change of free\nenergy on going from a simple reference system to the {\\em ab initio} system,\nwith thermal averages computed by {\\em ab initio} molecular dynamics\nsimulation. The reference system consists of the inverse-power pair-potential\nmodel used in previous work. The liquid-state free energy is combined with the\nfree energy of hexagonal close packed Fe calculated earlier using identical\n{\\em ab initio} techniques to obtain the melting curve and volume and entropy\nof melting. Comparisons of the calculated melting properties with experimental\nmeasurement and with other recent {\\em ab initio} predictions are presented.\nExperiment-theory comparisons are also presented for the pressures at which the\nsolid and liquid Hugoniot curves cross the melting line, and the sound speed\nand Gr\\\"{u}neisen parameter along the Hugoniot. Additional comparisons are made\nwith a commonly used equation of state for high-pressure/high-temperature Fe\nbased on experimental data."
    },
    {
        "anchor": "Systematical, experimental investigations on LiMgZ (Z= P, As, Sb) wide\n  band gap semiconductors: This work reports on the experimental investigation of the wide band gap\ncompounds LiMgZ (Z = P, As, Sb), which are promising candidates for\nopto-electronics and anode materials for Lithium batteries. The compounds\ncrystallize in the cubic (C1_b) MgAgAs structure (space group F-43m). The\npolycrystalline samples were synthesized by solid state reaction methods. X-ray\nand neutron diffraction measurements show a homogeneous, single-phased samples.\nThe electronic properties were studied using the direct current (DC) method.\nAdditionally UV-VIS diffuse reflectance spectra were recorded in order to\ninvestigate the band gap nature. The measurements show that all compounds\nexhibit semiconducting behavior with direct band gaps of 1.0 eV to 2.3 eV\ndepending on the Z element. A decrease of the peak widths in the static 7Li\nnuclear magnetic resonance (NMR) spectra with increasing temperature was\nobserved, which can directly be related to an increase of Li ion mobility.",
        "positive": "Beyond the Ginzburg-Landau theory of freezing: Anisotropy of the\n  interfacial free energy in the Phase-Field Crystal model: This paper re-visits the weakly fourth order anisotropic Ginzburg-Landau (GL)\ntheory of freezing. First we determine the anisotropy of the interfacial free\nenergy in the Phase-Field Crystal (PFC) model analytically, and prove that it\nremains finite at the critical point as a direct consequence of the one-mode\ndominance of the model. Next, we derive the leading order PFC amplitude model\nand show the formal analogy to traditional weakly 4th order anisotropic GL\ntheories. We conclude that the material-independent anisotropy appearing in\nemergent GL theory coincides with the remnant anisotropy of the generating PFC\nmodel. As a result, we show that the reduced temperature {\\epsilon} does not\nenter into the interfacial free energy anisotropy for metallic materials in\nboth the Phase-Field Crystal model and the emerging Ginzburg-Landau theories.\nFinally, we investigate the possible pathways of calibrating anisotropic\nGinzburg-Landau theories."
    },
    {
        "anchor": "Topological mosaic in Moir\u00e9 superlattices of van der Waals\n  heterobilayers: Van der Waals (vdW) heterostructures formed by 2D atomic crystals provide a\npowerful approach towards designer condensed matter systems. Incommensurate\nheterobilayers with small twisting and/or lattice mismatch lead to the\ninteresting concept of Moir\\'e superlattice, where the atomic registry is\nlocally indistinguishable from commensurate bilayers but has local-to-local\nvariation over long range. Here we show that such Moir\\'e superlattice can lead\nto periodic modulation of local topological order in vdW heterobilayers formed\nby two massive Dirac materials. By tuning the vdW heterojunction from normal to\nthe inverted type-II regime via an interlayer bias, the commensurate\nheterobilayer can become a topological insulator (TI), depending on the\ninterlayer hybridization controlled by the atomic registry between the vdW\nlayers. This results in mosaic pattern of TI regions and normal insulator (NI)\nregions in Moir\\'e superlattices, where topologically protected helical modes\nexist at the TI/NI phase boundaries. By using symmetry based k.p and\ntight-binding models, we predict that this topological phenomenon can be\npresent in inverted transition metal dichalcogenides heterobilayers. Our work\npoints to a new means of realizing programmable and electrically switchable\ntopological superstructures from 2D arrays of TI nano-dots to 1D arrays of TI\nnano-stripes.",
        "positive": "Anomalous Photon-Assisted Tunneling in Graphene: We investigated the Dirac electrons transmission through a potential barrier\nin the presence of circularly polarized light. An anomalous photon-assisted\nenhanced transmission is predicted and explained in a comparison with the\nwell-known Klein paradox. It is demonstrated that the perfect transmission for\nnearly-head-on collision in an infinite graphene is suppressed in gapped\ndressed states of electrons, which is further accompanied by shift of peaks as\na function of the incident angle away from the head-on collision. In addition,\nthe perfect transmission in the absence of potential barrier is partially\nsuppressed by a photon-induced gap in illuminated graphene. After the effect of\nrough edges of the potential barrier or impurity scattering is included, the\nperfect transmission with no potential barrier becomes completely suppressed\nand the energy range for the photon-assisted perfect transmission is reduced at\nthe same time."
    },
    {
        "anchor": "Spontaneous gap opening and potential excitonic states in an ideal Dirac\n  semimetal Ta$_2$Pd$_3$Te$_5$: The opening of an energy gap in the electronic structure generally indicates\nthe presence of interactions. In materials with low carrier density and short\nscreening length, long-range Coulomb interaction favors the spontaneous\nformation of electron-hole pairs, so-called excitons, opening an excitonic gap\nat the Fermi level. Excitonic materials host unique phenomenons associated with\npair excitations. However, there is still no generally recognized\nsingle-crystal material with excitonic order, which is, therefore, awaited in\ncondensed matter physics. Here, we show that excitonic states may exist in the\nquasi-one-dimensional material Ta$_2$Pd$_3$Te$_5$, which has an almost ideal\nDirac-like band structure, with Dirac point located exactly at Fermi level. We\nfind that an energy gap appears at 350 K, and it grows with decreasing\ntemperature. The spontaneous gap opening is absent in a similar material\nTa$_2$Ni$_3$Te$_5$. Intriguingly, the gap is destroyed by the potassium\ndeposition on the crystal, likely due to extra-doped carriers. Furthermore, we\nobserve a pair of in-gap flat bands, which is an analog of the impurity states\nin a superconducting gap. All these observations can be properly explained by\nan excitonic order, providing Ta$_2$Pd$_3$Te$_5$ as a new and promising\ncandidate realizing excitonic states.",
        "positive": "Nitrogen magneto-ionics: So far, magneto-ionics, understood as voltage-driven ion transport in\nmagnetic materials, has largely relied on controlled migration of oxygen\nion/vacancy and, to a lesser extent, lithium and hydrogen. Here, we demonstrate\nefficient, room-temperature, voltage-driven nitrogen transport (i.e., nitrogen\nmagneto-ionics) by electrolyte-gating of a single CoN film (without an\nion-reservoir layer). Nitrogen magneto-ionics in CoN is compared to oxygen\nmagneto-ionics in Co3O4, both layers showing a nanocrystalline\nface-centered-cubic structure and reversible voltage-driven ON-OFF\nferromagnetism. In contrast to oxygen, nitrogen transport occurs uniformly\ncreating a plane-wave-like migration front, without assistance of diffusion\nchannels. Nitrogen magneto-ionics requires lower threshold voltages and\nexhibits enhanced rates and cyclability. This is due to the lower activation\nenergy for ion diffusion and the lower electronegativity of nitrogen compared\nto oxygen. These results are appealing for the use of magneto-ionics in nitride\nsemiconductor devices, in applications requiring endurance and moderate speeds\nof operation, such as brain-inspired computing."
    },
    {
        "anchor": "Density of States Prediction for Materials Discovery via Contrastive\n  Learning from Probabilistic Embeddings: Machine learning for materials discovery has largely focused on predicting an\nindividual scalar rather than multiple related properties, where spectral\nproperties are an important example. Fundamental spectral properties include\nthe phonon density of states (phDOS) and the electronic density of states\n(eDOS), which individually or collectively are the origins of a breadth of\nmaterials observables and functions. Building upon the success of graph\nattention networks for encoding crystalline materials, we introduce a\nprobabilistic embedding generator specifically tailored to the prediction of\nspectral properties. Coupled with supervised contrastive learning, our\nmaterials-to-spectrum (Mat2Spec) model outperforms state-of-the-art methods for\npredicting ab initio phDOS and eDOS for crystalline materials. We demonstrate\nMat2Spec's ability to identify eDOS gaps below the Fermi energy, validating\npredictions with ab initio calculations and thereby discovering candidate\nthermoelectrics and transparent conductors. Mat2Spec is an exemplar framework\nfor predicting spectral properties of materials via strategically incorporated\nmachine learning techniques.",
        "positive": "Growth and Characterisation Studies of Eu$_3$O$_4$ Thin Films Grown on\n  Si/SiO$_2$ and Graphene: We report the growth, structural and magnetic properties of the less studied\nEu-oxide phase, Eu$_3$O$_4$, thin films grown on a Si/SiO$_2$ substrate and\nSi/SiO$_2$/graphene using molecular beam epitaxy. The X-ray diffraction scans\nshow that highly-textured crystalline Eu$_3$O$_4$(001) films are grown on both\nsubstrates, whereas the film deposited on graphene has a better crystallinity\nthan that grown on the Si/SiO$_2$ substrate. The SQUID measurements show that\nboth films have a Curie temperature of about 5.5 K, with a magnetic moment of\n0.0032 emu/g at 2 K. The mixed-valency of the Eu cations has been confirmed by\nthe qualitative analysis of the depth-profile X-ray photoelectron spectroscopy\nmeasurements with the Eu$^{2+}$ : Eu$^{3+}$ ratio of 28 : 72. However,\nsurprisingly, our films show no metamagnetic behaviour as reported for the bulk\nand powder form. Furthermore, the Raman spectroscopy scans show that the growth\nof the Eu$_3$O$_4$ thin films has no damaging effect on the underlayer graphene\nsheet. Therefore, the graphene layer is expected to retain its properties."
    },
    {
        "anchor": "Describing the diverse geometries of gold from nanoclusters to bulk-- a\n  first-principles based hybrid bond order potential: Molecular dynamics simulations using empirical force fields (EFFs) are\ncrucial for gaining fundamental insights into atomic structure and long\ntimescale dynamics of Au nanoclusters with far-reaching applications in energy\nand devices. This approach is thwarted by the failure of currently available\nEFFs in describing the size-dependent dimensionality and diverse geometries\nexhibited by Au clusters (e.g., planar, hollow cages, pyramids). Owing to their\nability to account for bond directionality, bond-order based EFFs, such as the\nTersoff-type Bond Order Potential (BOP), are well suited for such a\ndescription. Nevertheless, the predictive power of existing BOP parameters is\nseverely limited in the nm length scale owing to the predominance of bulk Au\nproperties used to train them. Here, we mitigate this issue by introducing a\nnew hybrid bond order potential (HyBOP), which account for (a) short-range\ninteractions via Tersoff-type BOP terms and (b) long-range effects by a scaled\nLJ term whose contribution depends on the local atomic density. We optimized\nthe independent parameters for our HyBOP using a global optimization scheme\ndriven by genetic algorithms. Moreover, to ensure good transferability of these\nparameters across different length scales, we used an extensive training\ndataset encompasses structural and energetic properties of a thousand 13-atom\nAu clusters, surface energies, as well as bulk polymorphs, obtained from\ndensity functional theory (DFT) calculations. Our newly developed HyBOP has\nbeen found to accurately describe (a) global minimum energy configurations at\ndifferent clusters sizes, (b) critical size of transition from planar to\nglobular clusters, (c) evolution of structural motifs with cluster size, and\n(d) thermodynamics, structure, elastic properties of bulk polymorphs as well as\nsurfaces, in excellent agreement with DFT calculations and spectroscopic\nexperiments.",
        "positive": "Towards a systematic assessment of errors in diffusion Monte Carlo\n  calculations of semiconductors: case study of zinc selenide and zinc oxide: The fixed node diffusion Monte Carlo (DMC) method has attracted interest in\nrecent years as a way to calculate properties of solid materials with high\naccuracy. However, the framework for the calculation of properties such as\ntotal energies, atomization energies, and excited state energies is not yet\nfully established. Several outstanding questions remain as to the effect of\npseudopotentials, the magnitude of the fixed node error, and the size of\nsupercell finite size effects. Here, we consider in detail the semiconductors\nZnSe and ZnO and carry out systematic studies to assess the magnitude of the\nenergy differences arising from controlled and uncontrolled approximations in\nDMC. The former include time step errors and supercell finite size effects for\nground and optically excited states, and the latter include pseudopotentials,\nthe pseudopotential localization approximation, and the fixed node\napproximation. We find that for these compounds, the errors can be controlled\nto good precision using modern computational resources, and that quantum Monte\nCarlo calculations using Dirac-Fock pseudopotentials can offer good estimates\nof both cohesive energy and the gap of these systems. We do however observe\ndifferences in calculated optical gaps that arise when different\npseudopotentials are used."
    },
    {
        "anchor": "Structure, Photophysics and the Order-Disorder Transition to the Beta\n  Phase in Poly(9,9-(di -n,n-octyl)fluorene): X-ray diffraction, UV-vis absorption and photoluminescence (PL) spectroscopy\nhave been used to study the well-known order-disorder transition (ODT) to the\nbeta phase in poly(9,9-(di n,n-octyl)fluorene)) (PF8) thin film samples through\ncombination of time-dependent and temperature-dependent measurements. The ODT\nis well described by a simple Avrami picture of one-dimensional nucleation and\ngrowth but crystallization, on cooling, proceeds only after molecular-level\nconformational relaxation to the so called beta phase. Rapid thermal quenching\nis employed for PF8 studies of pure alpha phase samples while extended\nlow-temperature annealing is used for improved beta phase formation. Low\ntemperature PL studies reveal sharp Franck-Condon type emission bands and, in\nthe beta phase, two distinguishable vibronic sub-bands with energies of\napproximately 199 and 158 meV at 25 K. This improved molecular level structural\norder leads to a more complete analysis of the higher-order vibronic bands. A\nnet Huang-Rhys coupling parameter of just under 0.7 is typically observed but\nthe relative contributions by the two distinguishable vibronic sub-bands\nexhibit an anomalous temperature dependence. The PL studies also identify\nstrongly correlated behavior between the relative beta phase 0-0 PL peak\nposition and peak width. This relationship is modeled under the assumption that\nemission represents excitons in thermodynamic equilibrium from states at the\nbottom of a quasi-one-dimensional exciton band. The crystalline phase, as\nobserved in annealed thin-film samples, has scattering peaks which are\nincompatible with a simple hexagonal packing of the PF8 chains.",
        "positive": "On the interaction of precipitates and tensile twins in magnesium alloys: Although magnesium alloys deform extensively through shear strains and\ncrystallographic re-orientations associated with the growth of twins, little is\nknown about the strengthening mechanisms associated with this deformation mode.\nA crystal plasticity based phase field model for twinning is employed in this\nwork to study the strengthening mechanisms resulting from the interaction\nbetween twin growth and precipitates. The full-field simulations reveal in\ngreat detail the pinning and de-pinning of a twin boundary at individual\nprecipitates, resulting in a maximum resistance to twin growth when the\nprecipitate is partially embedded in the twin. Furthermore, statistically\nrepresentative precipitate distributions are used to systematically investigate\nthe influence of key microstructural parameters such as precipitate\norientation, volume fraction, size, and aspect ratio on the resistance to twin\ngrowth. The results indicate that the effective critical resolved shear stress\n(CRSS) for twin growth increases linearly with precipitate volume fraction and\naspect ratio. For a constant volume fraction of precipitates, reduction of the\nprecipitate size below a critical level produces a strong increase in the CRSS\ndue to the Orowan-like strengthening mechanism between the twin interface and\nprecipitates. Above this level the CRSS is size independent. The results are\nquantitatively and qualitatively comparable with experimental measurements and\npredictions of mean-field strengthening models. Based on the results,\nguidelines for the design of high strength magnesium alloys are discussed."
    },
    {
        "anchor": "Torsional Force Microscopy of Van der Waals Moir\u00e9s and Atomic Lattices: In a stack of atomically-thin Van der Waals layers, introducing interlayer\ntwist creates a moir\\'e superlattice whose period is a function of twist angle.\nChanges in that twist angle of even hundredths of a degree can dramatically\ntransform the system's electronic properties. Setting a precise and uniform\ntwist angle for a stack remains difficult, hence determining that twist angle\nand mapping its spatial variation is very important. Techniques have emerged to\ndo this by imaging the moir\\'e, but most of these require sophisticated\ninfrastructure, time-consuming sample preparation beyond stack synthesis, or\nboth. In this work, we show that Torsional Force Microscopy (TFM), a scanning\nprobe technique sensitive to dynamic friction, can reveal surface and shallow\nsubsurface structure of Van der Waals stacks on multiple length scales: the\nmoir\\'es formed between bi-layers of graphene and between graphene and\nhexagonal boron nitride (hBN), and also the atomic crystal lattices of graphene\nand hBN. In TFM, torsional motion of an AFM cantilever is monitored as it is\nactively driven at a torsional resonance while a feedback loop maintains\ncontact at a set force with the sample surface. TFM works at room temperature\nin air, with no need for an electrical bias between the tip and the sample,\nmaking it applicable to a wide array of samples. It should enable determination\nof precise structural information including twist angles and strain in moir\\'e\nsuperlattices and crystallographic orientation of VdW flakes to support\npredictable moir\\'e heterostructure fabrication.",
        "positive": "Giant and supergiant electrical capacity of heterostructures on a basis\n  of advanced superionic conductors: The giant and supergiant electrical capacity are discovered in the\nheterostructures on a basis of advanced superionic conductors."
    },
    {
        "anchor": "Energy dependent wavelength of the ion induced nanoscale ripple: Wavelength variation of ion beam induced nanoscale ripple structure has\nreceived much attention recently due to its possible application in\nnanotechnology. We present here results of Ar$^+$ bombarded Si in the energy\nrange 50 to 140 keV to demonstrate that with beam scanning the ripple\nwavelength increases with ion energy and decreases with energy for irradiation\nwithout ion beam scanning. An expression for the energy dependence of ripple\nwavelength is proposed taking into simultaneous effect of thermally activated\nsurface diffusion and ion induced effective surface diffusion.",
        "positive": "Selective Functionalization of Halogens on Zigzag Graphene Nanoribbons:\n  A Route to the Separation of Zigzag Graphene Nanoribbons: Using the ab initio pseudopotential density functional method, we investigate\nthe functionalization of halogen molecules into graphene-based nanostructures\nwith zigzag and armchair edges. We find that halogen molecules adsorb through\nchemisorption on the zigzag edge carbon atoms with a binding energy of ~1-5 eV\nand their adsorption on a perfect zigzag edge is preferred, in sharp contrast\nto physisorption on the armchair edge and elsewhere where they adsorb with a\nbinding energy of ~0.07 eV. We suggest that our findings would be utilized for\nan approach to the separation of zigzag graphene nanoribbons with regular edges\nwith the change of the solubility of the functionalized nanoribbons."
    },
    {
        "anchor": "Inhomogeneous ferrimagnetic-like behavior in Gd2/3Ca1/3MnO3 single\n  crystals: We present a study of the magnetic properties of Gd2/3Ca1/3MnO3 single\ncrystals at low temperatures. We show that this material behave as an\ninhomogeneous ferrimagnet. In addition to small saturation magnetization at 5\nK, we have found history dependent effects in the magnetization and the\npresence of exchange bias. These features are compatible with microscopic phase\nseparation in the clean Gd2/3Ca1/3MnO3 system studied.",
        "positive": "Characterizing heterogeneous dynamics at hydrated electrode surfaces: In models of Pt 111 and Pt 100 surfaces in water, motions of molecules in the\nfirst hydration layer are spatially and temporally correlated. To interpret\nthese collective motions, we apply quantitative measures of dynamic\nheterogeneity that are standard tools for considering glassy systems.\nSpecifically, we carry out an analysis in terms of mobility fields and\ndistributions of persistence times and exchange times. In so doing, we show\nthat dynamics in these systems is facilitated by transient disorder in\nfrustrated two-dimensional hydrogen bonding networks. The frustration is the\nresult of unfavorable geometry imposed by strong metal-water bonding. The\ngeometry depends upon the structure of the underlying metal surface. Dynamic\nheterogeneity of water on the Pt 111 surface is therefore qualitatively\ndifferent than that for water on the Pt 100 surface. In both cases, statistics\nof this adlayer dynamic heterogeneity responds asymmetrically to applied\nvoltage."
    },
    {
        "anchor": "Electromechanical Probing of Ionic Currents in Energy Storage Materials: The electrochemical processes in energy storage materials are generally\nlinked with changes of molar volume of the host compound. Here, the frequency\ndependent strain response of 1D electrochemically active systems to periodic\nelectric bias is analyzed. The sensitivity and resolution of these\nelectrochemical strain measurements are compared to the current-based\nelectrochemical impedance spectroscopy. The resolution and detection limits of\ninterferometric and atomic force microscopy based systems for probing\nelectrochemical reactions on the nanoscale are analyzed.",
        "positive": "Magnetic Binary Supersaturated Solid Solutions Processed by Severe\n  Plastic Deformation: Samples consisting of one ferromagnetic and one diamagnetic component which\nare immiscible at the thermodynamic equilibrium (Co-Cu, Fe-Cu, Fe-Ag) are\nprocessed by high-pressure torsion at various compositions. The received\nmicrostructures are investigated by electron microscopy and synchrotron X-ray\ndiffraction, showing a microstructural saturation. Results gained from\nmicrostructural investigations are correlated to magnetometry data. The Co-Cu\nsamples show mainly ferromagnetic behavior and a decrease in coercivity with\nincreasing Co-content. The saturation microstructure of Fe-Cu samples is found\nto be dual phase. Results of magnetic measurements also revealed the occurrence\nof two different magnetic phases in this system. For Fe-Ag, the microstructural\nand magnetic results indicate that no intermixing between the elemental phases\ntakes place."
    },
    {
        "anchor": "High-density two-dimensional electron system induced by oxygen vacancies\n  in ZnO: We realize a two-dimensional electron system (2DES) in ZnO by simply\ndepositing pure aluminum on its surface in ultra-high vacuum, and characterize\nits electronic structure using angle-resolved photoemission spectroscopy. The\naluminum oxidizes into alumina by creating oxygen vacancies that dope the bulk\nconduction band of ZnO and confine the electrons near its surface. The electron\ndensity of the 2DES is up to two orders of magnitude higher than those obtained\nin ZnO heterostructures. The 2DES shows two $s$-type subbands, that we compare\nto the $d$-like 2DESs in titanates, with clear signatures of many-body\ninteractions that we analyze through a self-consistent extraction of the system\nself-energy and a modeling as a coupling of a 2D Fermi liquid with a Debye\ndistribution of phonons.",
        "positive": "On the Origins of Tension--Compression Asymmetry in Crystals and\n  Implications for Cyclic Behavior: Most of crystalline materials exhibit a hysteresis on their deformation curve\nwhen mechanically loaded in alternating directions. This Bauschinger effect is\nthe signature of mechanisms existing at the atomic scale and controlling the\nmaterials damage and ultimately their failure. Here, three-dimensional\nsimulations of dislocation dynamics and statistical analyses of the\nmicrostructure evolution reveal two original elementary mechanisms. An\nasymmetry in the dislocation network junctions arising from the stress driven\ncurvatures and the partial reversibility of plastic avalanches give an\nexplanation to the traction-compression asymmetry observed in FCC\nsingle-crystals. These mechanisms are then connected in a physically justified\nway to larger-scale representations using a dislocation density based theory.\nParameter-free predictions of the Bauschinger effect and strain hardening\nduring cyclic deformation in different materials and over a range of loading\ndirections and different plastic strain amplitudes are found to be in excellent\nagreement with experiments. This work brings invaluable mechanistic insights\nfor the interpretation of experiments and for the design of structural\ncomponents to consolidate their service life under cyclic load."
    },
    {
        "anchor": "Disorder control in crystalline GeSb2Te4 and its impact on\n  characteristic length scales: Crystalline GeSb2Te4 (GST) is remarkable material, as it allows to\ncontinuously tune the electrical resistance by orders of magnitude without\ninvolving a phase transition or stoichiometric changes, just by altering the\nshort-range order. While well-ordered specimen are metallic, increasing amounts\nof disorder can eventually lead to an insulating state with vanishing\nconductivity in the 0K limit, but a similar number of charge carriers. These\nobservations make disordered GST one of the most promising candidates for the\nrealization of a true Anderson insulator. While so far the low-temperature\nproperties have mostly been studied in films of small grain size, here a\nsputter-deposition process is employed that enables preparation of a large\nvariety of these GST states including metallic and truly insulating ones. By\ngrowing films of GST on mica substrates, biaxially textured samples with huge\ngrain sizes are obtained. A series of these samples is employed for transport\nmeasurements, as their electron mean free path can be altered by a factor of\n20. Yet, the mean free path always remains more than an order of magnitude\nsmaller than the lateral grain size. This proves unequivocally that grain\nboundaries play a negligible role for electron scattering, while intragrain\nscattering, presumably by disordered vacancies, dominates. Most importantly,\nthese findings underline that the Anderson insulating state as well as the\nsystem's evolution towards metallic conductivity are indeed intrinsic\nproperties of the material.",
        "positive": "Enhanced Performance of Dye-Sensitized Solar Cells based on TiO2\n  Nanotube Membranes using Optimized Annealing Profile: We use free-standing TiO2 nanotube membranes that are transferred onto FTO\nslides in front-side illuminated dye-sensitized solar cells (DSSCs). We\ninvestigate the key parameters for solar cell arrangement of self-ordered\nanodic TiO2 nanotube layers on the FTO substrate and namely the influence of\nthe annealing procedure on the DSSC light conversion efficiency. The results\nshow that using an optimal temperature annealing profile can significantly\nenhance the DSSC efficiency (in our case 9.8 %), as it leads to a markedly\nlower density of trapping states in the tube oxide, and thus to strongly\nimproved electron transport properties."
    },
    {
        "anchor": "Acceleration of the precession frequency for optically-oriented electron\n  spins in ferromagnetic/semiconductor hybrids: Time-resolved Kerr rotation measurements were performed in InGaAs/GaAs\nquantum wells nearby a doped Mn delta layer. Our magneto-optical results show a\ntypical time evolution of the optically-oriented electron spin in the quantum\nwell. Surprisingly, this is strongly affected by the Mn spins, resulting in an\nincrease of the spin precession frequency in time. This increase is attributed\nto the variation in the effective magnetic field induced by the dynamical\nrelaxation of the Mn spins. Two processes are observed during electron spin\nprecession: a quasi-instantaneous alignment of the Mn spins with photo-excited\nholes, followed by a slow alignment of Mn spins with the external transverse\nmagnetic field. The first process leads to an equilibrium state imprinted in\nthe initial precession frequency, which depends on pump power, while the second\nprocess promotes a linear frequency increase, with acceleration depending on\ntemperature and external magnetic field. This observation yields new\ninformation about exchange process dynamics and on the possibility of\nconstructing spin memories, which can rapidly respond to light while retaining\ninformation for a longer period.",
        "positive": "Magnetoelectric domain wall dynamics and its implications for\n  magnetoelectric memory: Domain wall dynamics in a magnetoelectric antiferromagnet is analyzed, and\nits implications for magnetoelectric memory applications are discussed.\nCr$_2$O$_3$ is used in the estimates of the materials parameters. It is found\nthat the domain wall mobility has a maximum as a function of the electric field\ndue to the gyrotropic coupling induced by it. In Cr$_2$O$_3$ the maximal\nmobility of 0.1 m/(s$\\times$Oe) is reached at $E\\approx0.06$ V/nm. Fields of\nthis order may be too weak to overcome the intrinsic depinning field, which is\nestimated for B-doped Cr$_2$O$_3$. These major drawbacks for device\nimplementation can be overcome by applying a small in-plane shear strain, which\nblocks the domain wall precession. Domain wall mobility of about 0.7\nm/(s$\\times$Oe) can then be achieved at $E=0.2$ V/nm. A split-gate scheme is\nproposed for the domain-wall controlled bit element; its extension to\nmultiple-gate linear arrays can offer advantages in memory density,\nprogrammability, and logic functionality."
    },
    {
        "anchor": "Electrical transport and magnetic properties of the triangular-lattice\n  compound Zr$_2$NiP$_2$: We report the first investigation of the electrical and magnetic properties\nof the triangular-lattice compound Zr$_2$NiP$_2$ (space group $P$6$_3$/$mmc$).\nThe temperature evolution of electrical resistivity follows the\nBloch-Gr\\\"uneisen-Mott law, and exhibits a typically metallic behavior. No\ntransition is visible by both electrical and magnetic property measurements,\nand nearly no magnetization is detected ($M_0$ $<$ 0.002$\\mu_\\mathrm{B}$/Ni)\ndown to 1.8 K up to 7 T. The metallic and nonmagnetic characters are well\nunderstood by the first-principles calculations for Zr$_2$NiP$_2$.",
        "positive": "The importance of inversion disorder in the visible light induced\n  persistent luminescence in Cr$^{3+}$ doped AB$_2$O$_4$ (A = Zn or Mg and B =\n  Ga or Al): Cr$^{3+}$ doped spinel compounds AB$_2$O$_4$ with A=Zn, Mg and B=Ga, Al\nexhibit a long near infrared persistent luminescence when excited with UV or\nX-rays. In addition, persistent luminescence of ZnGa$_2$O$_4$ and to a lesser\nextent MgGa$_2$O$_4$, can also be induced by visible light excitation via\n$^4$A$_2$ $ \\rightarrow $ $^4$T$_2$ transition of Cr$^{3+}$, which makes these\ncompounds suitable as biomarkers for in vivo optical imaging of small animals.\nWe correlate this peculiar optical property with the presence of antisite\ndefects, which are present in ZnGa$_2$O$_4$ and MgGa$_2$O$_4$. By using X-ray\nabsorption fine structure (XAFS) spectroscopy, associated with electron\nparamagnetic resonance (EPR) and optical emission spectroscopy, it is shown\nthat an increase in antisite defects concentration results in a decrease in the\nCr-O bond length and the octahedral crystal field energy. A part of the defects\nare in the close environment of Cr$^{3+}$ ions, as shown by the increasing\nstrain broadening of EPR and XAFS peaks observed upon increasing antisite\ndisorder. It appears that ZnAl$_2$O$_4$, which exhibits the largest crystal\nfield splitting of Cr$^{3+}$ and the smallest antisite disorder, does not show\nconsiderable persistent luminescence upon visible light excitation as compared\nto ZnGa$_2$O$_4$ and MgGa$_2$O$_4$. These results highlight the importance of\nCr$^{3+}$ ions with neighboring antisite defects in the mechanism of persistent\nluminescence exhibited by Cr$^{3+}$ doped AB$_2$O$_4$ spinel compounds."
    },
    {
        "anchor": "Magnetic field tuning of polaron losses in Fe doped BaTiO3 single\n  crystals: Artificial tuning of dielectric parameters can result from interface\nconductivity in polycrystalline materials. In ferroelectric single crystals, it\nwas already shown that ferroelectric domain walls can be the source of such\nartificial coupling. We show here that low temperature dielectric losses can be\ntuned by a dc magnetic field. Since such losses were previously ascribed to\npolaron relaxation we suggest this results from the interaction of hopping\npolarons with the magnetic field. The fact that this losses alteration has no\ncounterpart on the real part of the dielectric permittivity confirms that no\ninterface is to be involved in this purely dynamical effect. The contribution\nof mobile charges hopping among Fe related centers was confirmed by ESR\nspectroscopy showing maximum intensity at ca T\\sim40 K.",
        "positive": "A common magnetic origin for the Invar effects in fcc iron-based\n  ferromagnets: Using first-principles calculations, in conjunction with Ising magnetism, we\nundertake a theoretical study to elucidate the origin of the experimentally\nobserved Invar effects in disordered fcc iron-based ferromagnets. First, we\nshow that our theory can account for the Invar effects in iron-nickel alloys,\nthe anomalies being driven by the magnetic contributions to the average free\nenergies. Second, we present evidence indicating that the relationship between\nthermal expansion and magnetism is essentially the same in all the studied\nalloys, including those which display the Invar effect and those which do not.\nHence we propose that magnetism plays a crucial role in determining whether a\nsystem exhibits normal thermal expansion, the Invar effect, or something else.\nThe crucial determining factor is the rate at which the relative orientation of\nthe local magnetic moments of nearest-neighbor iron atoms fluctuates as the\nsystem is heated."
    },
    {
        "anchor": "Direct measurement of electrocaloric effect based on multi-harmonic\n  lock-in thermography: In this study, we report on a direct measurement method for the\nelectrocaloric effect, the heating/cooling upon application/removal of an\nelectric field in dielectric materials, based on a lock-in thermography\ntechnique. By use of sinusoidal excitation and multi-harmonic detection, the\nactual temperature change can be measured by a single measurement in the\nfrequency domain even when the electrocaloric effect shows nonlinear response\nto the excitation field. We have demonstrated the method by measuring the\ntemperature dependence of the electric-field-induced temperature change for two\nSr-doped BaTiO$_3$ systems with different ferroelectric-paraelectric phase\ntransition temperatures, where the procedure for extracting the pure\nelectrocaloric contribution free from heat losses and Joule heating due to\nleakage currents is introduced. This method can be used irrespective of the\ntype of dielectric materials and enables simultaneous estimation of the\npolarization change and power dissipation during the application of the\nelectric field, being a convenient imaging measurement method for the\nelectrocaloric effect.",
        "positive": "Morphology Transition with Temperature and their Effect on Optical\n  Properties of Colloidal MoS$_2$ Nanostructures: Morphology plays a crucial role in deciding the chemical and optical\nproperties of nanomaterials due to confinement effects. We report the\nmorphology transition of colloidal molybdenum disulfide (MoS$_2$)\nnanostructures, synthesized by one pot heat-up method, from mix of quantum dots\n(QDs) and nanosheets to predominantly nanorods by varying the synthesis\nreaction temperature from 90 to 160 degree C. The stoichiometry and composition\nof the synthesized QDs, nanosheets and nanorods have been quantified to be\nMoS$_2$ using energy dispersive X-ray spectroscopy and X-ray photoelectron\nspectroscopy analysis. Nanostructure morphology transition due to variation in\nreaction temperature has resulted in photoluminescence quantum yield\nenhancement from zero to 4.4% on increase in temperature from 90 to 120 degree\nC. On further increase in temperature to 160 degree C, a decrease in quantum\nyield to 2.63% is observed. A red shift of 18 nm and 140 nm in the emission\nmaxima and absorption edge respectively is observed for the synthesized\nnanostructures with increase in reaction temperature from 90 to 160 degree C.\nThe change in the quantum yield is attributed to the change in shape and hence\nconfinement of charge carriers. To the best of our knowledge, first-time\nmicroscopic analysis of colloidal MoS$_2$ nanostructures shape and optical\nproperty variation with temperature explained by non-classical growth mechanism\nis presented."
    },
    {
        "anchor": "Ordering in red abalone nacre: Red abalone nacre is an intensely studied biomineral, and yet its formation\nmechanism remains poorly understood. Here we report quantitative measurements\nprobing the degree of order of the aragonite tablets in nacre, and show that\norder develops over a distance of about 50 microns. These observations indicate\nthat the orientational order of aragonite tablets in nacre is established\ngradually and dynamically, and we show that a model of controlled assembly\nbased on suppression of the crystal growth rate along a specific direction,\nwhen growth is confined in a layered structure, yields a tablet pattern\nconsistent with those revealed by detailed experimental measurements. This work\nprovides strong evidence that the organism s control of crystal orientation in\nnacre occurs via regulation of crystal nucleation and growth as opposed to\ndirect templation or heteroepitaxial growth on organic molecules on the organic\nmatrix sheets.",
        "positive": "Giant segregation transition as origin of liquid metal embrittlement in\n  the Fe-Zn system: A giant Zn segregation transition is revealed using CALPHAD-integrated\ndensity-based modelling of segregation into Fe grain boundaries (GBs). The\nresults show that above a threshold of only a few atomic percent Zn in the\nalloy, a substantial amount of up to 60 at.\\% Zn can segregate to the GB. We\nfound that the amount of segregation abruptly increases with decreasing\ntemperature, while the Zn content in the alloy required for triggering the\nsegregation transition decreases. Direct evidence of the Zn segregation\ntransition is obtained using high-resolution scanning transmission electron\nmicroscopy. Base on the model, we trace the origin of the segregation\ntransition back to the low cohesive energy of Zn and a miscibility gap in Fe-Zn\nGB, arising from the magnetic ordering effect, which is confirmed by ab-initio\ncalculations. We also show that the massive Zn segregation resulting from the\nsegregation transition greatly assists with liquid wetting and reduces the work\nof separation along the GB. The current predictions suggest that control over\nZn segregation, by both alloy design and optimizing the galvanization and\nwelding processes, may offer preventive strategies against liquid metal\nembrittlement."
    },
    {
        "anchor": "Defect-driven ferrimagnetism and hidden magnetization in MnBi$_2$Te$_4$: MnBi$_2$Te$_4$ (MBT) materials are promising antiferromagnetic topological\ninsulators where field driven ferromagnetism is predicted to cause a transition\nbetween axion insulator and Weyl semimetallic states. However, the presence of\nantiferromagnetic coupling between Mn/Bi antisite defects and the main Mn layer\ncan reduce the low-field magnetization, and it has been shown that such defects\nare more prevalent in the structurally identical trivial magnetic insulator\nMnSb$_2$Te$_4$ (MST). We use high-field magnetization measurements to show that\nthe magnetization of MBT and MST occur in stages and full saturation requires\nfields of~$\\sim$~60 Tesla. As a consequence, the low-field magnetization\nplateau state in MBT, where many determinations of quantum anomalous Hall state\nare studied, actually consists of ferrimagnetic septuple blocks containing both\na uniform and staggered magnetization component.",
        "positive": "Ab initio self-consistent many-body theory of polarons at all couplings: We present a theoretical framework to describe polarons from first principles\nwithin a many-body Green's function formalism. Starting from a general\nelectron-phonon Hamiltonian, we derive a self-consistent Dyson equation in\nwhich the phonon-mediated self-energy is composed by two distinct terms. One\nterm is the Fan-Migdal self-energy and describes dynamic electron-phonon\nprocesses, the other term is a new contribution to the self-energy originating\nfrom the static displacements of the atomic nuclei in the polaronic ground\nstate. The lowest-order approximation to the present theory yields the standard\nmany-body perturbation theory approach to electron-phonon interactions in the\nlimit of large polarons, and the ab initio polaron equations introduced in [Sio\net al., Phys. Rev. B 99, 235139 (2019); Phys. Rev. Lett. 122, 246403 (2019)] in\nthe limit of small polarons. A practical recipe to implement the present\nunifying formalism in first-principles calculations is outlined. We apply our\nmethod to the Fr\\\"ohlich model, and obtain remarkably accurate polaron energies\nat all couplings, in line with Feynman's polaron theory and diagrammatic Monte\nCarlo calculations. We also recover the well-known results of Fr\\\"ohlich and\nPekar at weak and strong coupling, respectively. The present approach enables\npredictive many-body calculations of polarons in real materials at all\ncouplings."
    },
    {
        "anchor": "Screened Coulomb interactions in metallic alloys: I. Universal screening\n  in the atomic sphere approximation: We have used the locally self-consistent Green's function (LSGF) method in\nsupercell calculations to establish the distribution of the net charges\nassigned to the atomic spheres of the alloy components in metallic alloys with\ndifferent compositions and degrees of order. This allows us to determine the\nMadelung potential energy of a random alloy in the single-site mean field\napproximation which makes the conventional single-site density-functional-\ntheory coherent potential approximation (SS-DFT-CPA) method practically\nidentical to the supercell LSGF method with a single-site local interaction\nzone that yields an exact solution of the DFT problem. We demonstrate that the\nbasic mechanism which governs the charge distribution is the screening of the\nnet charges of the alloy components that makes the direct Coulomb interactions\nshort-ranged. In the atomic sphere approximation, this screening appears to be\nalmost independent of the alloy composition, lattice spacing, and crystal\nstructure. A formalism which allows a consistent treatment of the screened\nCoulomb interactions within the single-site mean-filed approximation is\noutlined. We also derive the contribution of the screened Coulomb interactions\nto the S2 formalism and the generalized perturbation method.",
        "positive": "Tunable spider-web inspired hybrid labyrinthine acoustic metamaterials\n  for low-frequency sound control: Attenuating low-frequency sound remains a challenge, despite many advances in\nthis direction. Recently developed acoustic metamaterials enable efficient\nsubwavelength wave manipulation and attenuation due to exotic effects such as\nunusually high reflectivity, negative refraction or cloaking. In particular,\nlabyrinthine acoustic metamaterials can provide broadband sound reduction and\nexhibit extremely high effective refractive index values due to their\ncharacteristic topological architecture. In this paper, we design a novel\nlabyrinthine metamaterial with hybrid characteristics compared to previously\nproposed structures, by exploiting a spider web-inspired configuration. The\ndeveloped metamaterial structure is characterized by additional tunability of\nthe frequencies at which band gaps or negative group velocity modes occur, thus\nenabling versatility in the functionalities of the resulting structures. Time\ntransient simulations demonstrate the effectiveness of the proposed\nmetamaterials in manipulating wave fields in terms of transmission/reflection\ncoefficients, amplitude attenuation and time delay properties in broadband\nfrequency ranges. Results could find applications in the development of\npractical lightweight acoustic shielding structures with enhanced broadband\nwave-reflecting performance."
    },
    {
        "anchor": "Tight-binding branch-point energies and band offsets for cubic InN, GaN,\n  AlN and AlGaN alloys: Starting with empirical tight-binding band structures, the branch-point (BP)\nenergies and resulting valence band offsets (VBOs) for the zincblende phase of\nInN, GaN and AlN are calculated from their k-averaged midgap energy.\nFurthermore, the directional dependence of the BPs of GaN and AlN is discussed\nusing the Green's function method of Tersoff. We then show how to obtain the\nBPs for binary semiconductor alloys within a band-diagonal representation of\nthe coherent potential approximation (CPA) and apply this method to cubic AlGaN\nalloys. The resulting band offsets show good agreement to available\nexperimental and theoretical data from the literature. Our results can be used\nto determine the band alignment in isovalent heterostructures involving pure\ncubic III-nitrides or AlGaN alloys for arbitrary concentrations.",
        "positive": "Structure and dynamics of Rh surfaces: Lattice relaxations, surface phonon spectra, surface energies, and work\nfunctions are calculated for Rh(100) and Rh(110) surfaces using\ndensity-functional theory and the full-potential linearized augmented plane\nwave method. Both, the local-density approximation and the generalized gradient\napproximation to the exchange-correlation functional are considered. The force\nconstants are obtained from the directly calculated atomic forces, and the\ntemperature dependence of the surface relaxation is evaluated by minimizing the\nfree energy of the system. The anharmonicity of the atomic vibrations is taken\ninto account within the quasiharmonic approximation. The importance of\ncontributions from different phonons to the surface relaxation is analyzed."
    },
    {
        "anchor": "On the influence of inversion on thermal properties of magnesium gallium\n  spinel: Measurements of thermal diffusivity \\k{appa} (using laser flash analysis) for\ntemperatures from 100 {\\deg}C to 1200 {\\deg}C and of the inversion parameter x\n(using X-ray analysis) for the single crystal spinel MgGa2O4 have been\nperformed. X-ray analysis showed a small change in x for samples annealed at\n800 {\\deg}C (x = 0.838) and 1200 {\\deg}C (x = 0.834). Thermal diffusivity\nrevealed a significant rise of \\k{appa} for temperatures higher than 950\n{\\deg}C, deviating from the typical 1/T drop of \\k{appa}. An additional\nsystematic rise of \\k{appa} with time is observed for temperatures between 950\n{\\deg}C and 1100 {\\deg}C. A connection between cation disordering processes\ntypical for spinels at elevated temperatures and the observed deviation of\n\\k{appa} is proposed: Data indicate that cations changing their occupancy site\nat equilibration processes contribute significantly to \\k{appa} and therefore\nrepresent a new type of heat transport.",
        "positive": "Anomalies in the core level spectroscopy of a noncentrosymmetric solid,\n  BiPd: Understanding exotic solids is a difficult task as interactions are often\nhidden by the symmetry of the system. Here, we study the electronic properties\nof a noncentrosymmetric solid, BiPd, which is a rare material exhibiting both\nsuperconductivity and topological phase of matter. Employing high resolution\nphotoemission spectroscopy with photon energies ranging from hard x-ray to\nextreme ultraviolet regime, we show that hard x-ray spectroscopy alone is not\nenough to reveal surface-bulk differences in the electronic structure. We\nderived the escape depths close to the extreme surface sensitivity and find\nthat the photon energies used for high resolution measurements such as ARPES\nfall in the surface sensitive regime. In addition, we discover deviation of the\nbranching ratio of Bi core level features derived from conventional quantum\ntheories of the core hole final states. Such paradigm shift in core level\nspectroscopy can be attributed to the absence of center of symmetry and\nspin-orbit interactions."
    },
    {
        "anchor": "Chiral effect in plane isotropic micropolar elasticity and its\n  application to chiral lattices: In continuum mechanics, the non-centrosymmetric micropolar theory is usually\nused to capture the chirality inherent in materials. However when reduced to a\ntwo dimensional (2D) isotropic problem, the resulting model becomes non-chiral.\nTherefore, influence of the chiral effect cannot be properly characterized by\nexisting theories for 2D chiral solids. To circumvent this difficulty, based on\nreinterpretation of isotropic tensors in a 2D case, we propose a continuum\ntheory to model the chiral effect for 2D isotropic chiral solids. A single\nmaterial parameter related to chirality is introduced to characterize the\ncoupling between the bulk deformation and the internal rotation which is a\nfundamental feature of 2D chiral solids. Coherently, the proposed continuum\ntheory is also derived for a triangular chiral lattice from a homogenization\nprocedure, from which the effective material constants of the lattice are\nanalytically determined. The unique behavior in the chiral lattice is\ndemonstrated through the analyses of a static tension problem and a plane wave\npropagation problem. The results, which cannot be predicted by the non-chiral\nmodel, are validated by the exact solution of the discrete model.",
        "positive": "Chiral spin spiral in synthetic antiferromagnets probed by circular\n  dichroism in x-ray resonant magnetic scattering: Noncollinear chiral spin textures in ferromagnetic multilayers are at the\nforefront of recent research in nano-magnetism with the promise for fast and\nenergy-efficient devices. The recently demonstrated possibilities to stabilize\nsuch chiral structures in synthetic antiferromagnets (SAF) has raised interests\nas they are immune to dipolar field, hence favoring the stabilization of ultra\nsmall textures, improve mobility and avoid the transverse deflections of moving\nskyrmions limiting the efficiency in some foreseen applications. However, such\nsystems with zero net magnetization are hence difficult to characterize by most\nof the standard techniques. Here, we report that the relevant parameters of a\nmagnetic SAF texture, those being its period, its type (N\\'eel or Bloch) and\nits chirality (clockwise or counterclockwise), can be directly determined using\nthe circular dichroism in x-ray resonant scattering (CD-XRMS) at half integer\nmultilayer Bragg peaks in reciprocal space. The analysis of the dependence in\ntemperature down to 40K allows us moreover to address the question of the\ntemperature stability of a spin spiral in a SAF sample and of the temperature\nscaling of the symmetric and antisymmetric exchange interactions."
    },
    {
        "anchor": "Nickel coated carbon nanotubes in aluminum matrix composites: A\n  multiscale simulation study: In this work we use density functional theory (DFT) calculations to benchmark\nempirical potentials for the interaction between nickel and sp$^2$ bonded\ncarbon nanoparticles. These potentials are then used in order to investigate\nhow Ni decorated or coated carbon nanotubes (CNT) affect the mechanical\nproperties of Al/CNT composites. In particular we look at the pull-out\nbehaviour of pristine as well as Ni-decorated and Ni-coated CNT from an Al\nmatrix. Our result shows that Ni coating may produce an extended interface\n(interphase) where a significant amount of energy is dissipated during CNT\npull-out, leading to a high pull-out force. We also demonstrate that surface\ndecorated CNT may act as efficient nano-crystallization agents and thus provide\na novel strengthening mechanism not previously discussed in the literature. We\ndiscuss our results in view of promising approaches for engineering CNT-metal\ninterfaces such as to achieve high strength metal-CNT composite.",
        "positive": "Pick-up and drop transfer of diamond nanosheets: Nanocrystalline diamond (NCD) is a promising material for electronic and\nmechanical micro- and nanodevices. Here we introduce a versatile pick-up and\ndrop technique that makes it possible to investigate the electrical, optical\nand mechanical properties of as-grown NCD films. Using this technique, NCD\nnanosheets, as thin as 55 nm, can be picked-up from a growth substrate and\npositioned on another substrate. As a proof of concept, electronic devices and\nmechanical resonators are fabricated and their properties are characterized. In\naddition, the versatility of the method is further explored by transferring NCD\nnanosheets onto an optical fibre, which allows measuring its optical\nabsorption. Finally, we show that NCD nanosheets can also be transferred onto\n2D crystals, such as MoS2, to fabricate heterostructures. Pick-up and drop\ntransfer enables the fabrication of a variety of NCD-based devices without\nrequiring lithography or wet processing."
    },
    {
        "anchor": "Application of Thomas-Fermi model to a negative hydrogen ion in a strong\n  electric field: Thomas-Fermi model is applied to describe some basic properties of a negative\nhydrogen ion in a strong electric field. The equilibrium ionic size, energy and\npolarizability of the ion are calculated. Collective modes of the dipole\noscillations are regarded. A barrier, due to which the ion is in a stable\nstate, is studied. The barrier vanishes at some large value of the electric\nfield, which is defined as a critical value. The dependence of the critical\nfield on frequency is studied. At high frequencies a stripping mechanism for\ninstability arises. At the resonant frequency comparatively low amplitude of\nthe electric field causes the stripping instability.",
        "positive": "Coupling of Length Scales and Atomistic Simulation of MEMS Resonators: We present simulations of the dynamic and temperature dependent behavior of\nMicro-Electro-Mechanical Systems (MEMS) by utilizing recently developed\nparallel codes which enable a coupling of length scales. The novel techniques\nused in this simulation accurately model the behavior of the mechanical\ncomponents of MEMS down to the atomic scale. We study the vibrational behavior\nof one class of MEMS devices: micron-scale resonators made of silicon and\nquartz. The algorithmic and computational avenue applied here represents a\nsignificant departure from the usual finite element approach based on continuum\nelastic theory. The approach is to use an atomistic simulation in regions of\nsignificantly anharmonic forces and large surface area to volume ratios or\nwhere internal friction due to defects is anticipated. Peripheral regions of\nMEMS which are well-described by continuum elastic theory are simulated using\nfinite elements for efficiency. Thus, in central regions of the device, the\nmotion of millions of individual atoms is simulated, while the relatively large\nperipheral regions are modeled with finite elements. The two techniques run\nconcurrently and mesh seamlessly, passing information back and forth. This\ncoupling of length scales gives a natural domain decomposition, so that the\ncode runs on multiprocessor workstations and supercomputers. We present novel\nsimulations of the vibrational behavior of micron-scale silicon and quartz\noscillators. Our results are contrasted with the predictions of continuum\nelastic theory as a function of size, and the failure of the continuum\ntechniques is clear in the limit of small sizes. We also extract the Q value\nfor the resonators and study the corresponding dissipative processes."
    },
    {
        "anchor": "Dislocation interactions in olivine control postseismic creep of the\n  upper mantle: Changes in stress applied to mantle rocks, such as those imposed by\nearthquakes, induce a period of evolution in viscosity and microstructure. This\ntransient creep is often modelled based on stress transfer among slip systems\ndue to grain interactions. However, recent experiments have demonstrated that\nthe intragranular accumulation of stresses among dislocations is the dominant\ncause of strain hardening in olivine at low temperatures, raising the question\nof whether the same process contributes to transient creep at higher\ntemperatures. Here, we demonstrate that olivine samples deformed at 25{\\deg}C\nor 1150 to 1250{\\deg}C both contain stress heterogeneities of ~1 GPa that are\nimparted by dislocations and have correlation lengths of ~1 micrometre. The\nsimilar stress distributions formed in both temperature regimes indicate that\naccumulation of stresses among dislocations also provides a contribution to\ntransient creep at high temperatures. The results motivate a new generation of\nmodels that capture these intragranular processes and may refine predictions of\nevolving mantle viscosity over the earthquake cycle.",
        "positive": "Aggregation According to Classical Kinetics--From Nucleation to\n  Coarsening: We solve the standard Lifshitz-Slyozov (LS) model with conservation of total\nparticles in the limit of small super-saturation. The new element is an\neffective initial condition that follows from the initial exhaustion of\nnucleation as described in a previous paper [Farjoun and Neu, Phys. Rev. E 78].\nThe effective initial condition is characterized by a narrow distribution of\ncluster-sizes, all much larger than critical. In the subsequent solution, one\nof the LS similarity solutions emerges as the long-time limit, as expected. But\nour solution tells more. In particular, there is a \"growth\" era prior to what\nis usually called \"coarsening\". During \"growth\" the clusters (all of nearly the\nsame size much larger than critical) eventually exhaust the super-saturation\n(the exhaustion of nucleation in the previous era results from only a small\ndecrease in super-saturation). This allows the critical size to catch up to the\nclusters, and the traditional \"coarsening\" begins: Subcritical clusters\ndissolve and fuel the growth of the remaining super-critical clusters. Our\nanalysis tracks the evolution of cluster sizes during growth and coarsening by\ncomplimentary use of asymptotic and numerical methods. We establish\ncharacteristic times and cluster sizes associated with growth and coarsening\nfrom physical parameters and the initial super-saturation. The emerging\ndistribution is discontinuous at the largest cluster size, and our model\nselects the discontinuous LS similarity solution as the long time limit. There\nare strong indications that the smooth similarity solution proposed in the\noriginal LS paper emerges on a, yet longer, late-coarsening time-scale."
    },
    {
        "anchor": "New Phases of Water Ice Predicted at Megabar Pressures: Based on density functional calculations we predict water ice to attain two\nnew crystal structures with Pbca and Cmcm symmetry at 7.6 and 15.5 Mbar,\nrespectively. The known high pressure ice phases VII, VIII, X, and Pbcm as well\nas the Pbca phase are all insulating and composed of two interpenetrating\nhydrogen bonded networks, but the Cmcm structure is metallic and consists of\ncorrugated sheets of H and O atoms. The H atoms are squeezed into octahedral\npositions between next-nearest O atoms while they occupy tetrahedral positions\nbetween nearest O atoms in the ice X, Pbcm, and Pbca phases.",
        "positive": "Suppression of multiferroic order in hexagonal YMn1-xInxO3 ceramics: We have investigated the effects of substituting In for Mn on the\nantiferromagnetic phase transition in YMnO3 using magnetic, dielectric, and\nspecific heat measurements. We prepared a set of isostructural phase pure\nhexagonal YMn$_{1-x}$In$_{x}$O$_{3}$ samples having x=0 to x=0.9, which exhibit\na systematic decrease of the antiferromagnetic ordering temperature with\nincreasing In content. The multiferroic phase, which develops below TN, appears\nto be completely suppressed for x$\\geq$0.5 in the temperature range\ninvestigated, which can be attributed solely to the dilution of magnetic\ninteractions as the crystal structure remains hexagonal. Similar to previous\nreports, we find an enhancement of the magnetocapacitive coupling on dilution\nwith non-magnetic ions."
    },
    {
        "anchor": "A pair of FRET dyes designed to measure nano-scale contact and the\n  associated adhesion force: Interfacial adhesion is caused by intermolecular forces that only occur\nbetween surfaces at nano-scale contact (NSC) i.e., 0.1-0.4nm. To evaluate NSC\nand its influence on adhesion, F\\\"orster resonance energy transfer (FRET)\nspectroscopy has been used. FRET is a technique capable to measure nanometric\ndistances between surfaces by taking advantage of the interaction amid some\nspecific fluorescence molecules, named donor and acceptor. The F\\\"orster radius\n(R0) of the FRET pair indicates the distance detection range (0.5R0-2R0) of the\nsystem and, must be selected considering the final purpose of each study. Here,\nwe propose a new FRET pair: 7-Amino-4-methyl-cumarin (C120) and\n5(6)-Carboxy-2',7'-dichlor-fluorescein (CDCF) with high quantum yield (QY,\nQYC120=0.91 and QYCDCF=0.64) and a distance range of 0.6-2.2nm (0.1 mM)\nspecifically developed to measure NSC between soft surfaces. For this,\npolymeric thin films were bonded using different loads, from 1.5 to 150 bar, to\ncreate different degrees of NSC, analyzed by FRET spectroscopy, and later\npulled apart to measure their interfacial separation energy (adhesion force).\nOur experiments showed that NSC increases with the applied pressure in the\nbonded thin films, leading to higher FRET intensity and adhesion\nforce/separation energy. Thus, we have validated a new FRET pair, suitable to\nmeasure the degree of NSC between surfaces and establish a linear relationship\nbetween FRET and adhesion force; which can be of interest for any type of study\nwith soft materials interfaces that include NSC and its influence on adhesion,\nas sealants, adhesives or sensors.",
        "positive": "Jahn-Teller driven perpendicular magnetocrystalline anisotropy in\n  metastable Ruthenium: A new metastable phase of the body-centered-tetragonal ruthenium ({\\em\nbct}--Ru) is identified to exhibit a large perpendicular magnetocrystalline\nanisotropy (PMCA), whose energy, $E_{MCA}$, is as large as 150 $\\mu$eV/atom,\ntwo orders of magnitude greater than those of 3$d$ magnetic metals. Further\ninvestigation over the range of tetragonal distortion suggests that the\nappearance of the magnetism in the {\\em bct}--Ru is governed by the Jahn-Teller\nspit $e_g$ orbitals. Moreover, from band analysis, MCA is mainly determined by\nan interplay between two $e_g$ states, $d_{x^2-y^2}$ and $d_{z^2}$ states, as a\nresult of level reversal associated with tetragonal distortion."
    },
    {
        "anchor": "Tuning exchange interactions in antiferromagnetic Fe/W(001) by 4d\n  transition-metal overlayers: We use first-principles calculations based on density functional theory to\nstudy how the magnetic properties of an Fe monolayer on a W(001) surface --\nexhibiting a $c(2 \\times 2)$ antiferromagnetic ground state -- can be modified\nby an additional 4d transition-metal overlayer. To obtain an overview of how\nthe 4d-band filling influences the exchange interactions in the Fe layer we\nhave calculated the energy dispersion of spin spirals for 4d/Fe/2W unsupported\nquadlayers, in which the W(001)substrate is represented by only two atomic\nlayers. Hybridization with the overlayer leads to a reduced ferromagnetic\nnearest-neighbor exchange interaction and the next-nearest neighbor exchange\ngains in strength. Surprisingly, we find that the $c(2 \\times 2)$\nantiferromagnetic state is unfavorable for all systems with a 4d overlayer. For\n4d overlayers from the beginning (Nb) or end (Pd) of the series we find a\nferromagnetic ground state. As one moves to the center of the series there is a\ntransition via a spin spiral (Mo, Rh) to a $p (2 \\times 1)$ antiferromagnetic\nground state (Tc, Ru). We have studied the Mo, Ru, and Pd overlayer on\nFe/W(001) representing the surface by a sufficiently large number of W layers\nto obtain bulk like properties in its center. The energy dispersion of spin\nspirals show qualitatively the same results as those from the 4\\textit{d}/Fe/2W\nquadlayers. The Dzyaloshinskii-Moriya interaction calculated upon including\nspin-orbit coupling shows significant strength and considerable frustration\neffects. The calculated magnetocrystalline anisotropy energy is large as well.\nAll 4d/Fe/W(001) films are potential candidates for complex non-collinear spin\nstructures.",
        "positive": "Understanding and Minimizing $V_{OC}$ Losses in All-Perovskite Tandem\n  Photovoltaics: All-perovskite tandem solar cells promise high photovoltaic performance at\nlow cost. So far however, their efficiencies cannot compete with traditional\ninorganic multi-junction solar cells and they generally underperform in\ncomparison to what is expected from the isolated single junction devices.\nUnderstanding performance losses in all-perovskite tandem solar cells is a\ncrucial aspect that will accelerate advancement. Here, we perform extensive\nselective characterization of the individual sub-cells to disentangle the\ndifferent losses and limiting factors in these tandem devices. We find that\nnon-radiative losses in the high-gap subcell dominate the overall recombination\nlosses in our baseline system as well as in the majority of literature reports.\nWe consecutively improve the high-gap perovskite subcell through a\nmulti-faceted approach, allowing us to enhance the open-circuit voltage\n($V_{OC}$) of the subcell by up to 120 mV. Due to the (quasi) lossless indium\noxide interconnect which we employ for the first time in all-perovskite\ntandems, the $V_{OC}$ improvements achieved in the high-gap perovskites\ntranslate directly to improved all-perovskite tandem solar cells with a\nchampion $V_{OC}$ of 2.00 V and a stabilized efficiency of 23.7%. The\nefficiency potential of our optimized all-perovskite tandems reaches 25.2% and\n27.0% when determined from electro- and photo-luminescence respectively,\nindicating significant transport losses as well as imperfect energy-alignment\nbetween the perovskite and the transport layers in the experimental devices.\nFurther improvements to 28.4% are possible considering the bulk quality of both\nabsorbers measured using photo-luminescence on isolated perovskite layers. Our\ninsights therefore not only show an optimization example but a generalizable\nevidence-based strategy for optimization utilizing optical sub-cell\ncharacterization."
    },
    {
        "anchor": "Compliant substrate epitaxy: Au on MoS$_2$: The epitaxial growth of {111} oriented Au on MoS$_2$ is well documented\ndespite the large lattice mismatch (~8% biaxial strain), and the fact that a Au\n{001} orientation results in much less elastic strain. An analysis based on\ndensity functional and linear elasticity theories reveals that the {111}\norientation is stabilized by a combination of favorable surface and interfacial\ncontributions to the energy, and the compliance of the first layer of the\nMoS$_2$.",
        "positive": "Epitaxial growth of hexagonal tungsten bronze CsxWO3 films in\n  superconducting phase region exceeding bulk limit: We report epitaxial synthesis of superconducting CsxWO3 (x = 0.11, 0.20,\n0.31) films on Y-stabilized ZrO2 (111) substrates. The hexagonal crystal\nstructure was verified not only for composition within the stable region of\nbulk (x = 0.20, 0.31), but also for the out-of-range composition (x = 0.11).\nThe onset of superconducting transition temperature (TC) was recorded 5.8 K for\nx = 0.11. We found strong correlation between TC and c-axis length,\nirrespective of the Cs content. The results indicate that hidden\nsuperconducting phase region of hexagonal tungsten bronze is accessible by\nusing epitaxial synthesis of lightly doped films."
    },
    {
        "anchor": "Delving into the anisotropic interlayer exchange in bilayer CrI$_3$: Bilayer CrI$_3$ attracted much attention owing to peculiar switching between\nthe layered ferromagnetic and antiferromagnetic order upon stacking\nalternation. This finding pointed out the importance of the apparently small\ninterlayer exchange, yet, existing literature addresses only its isotropic\npart. To fill this gap, we combine the density functional theory with\nHamiltonian modeling to examine the anisotropic interlayer exchange in bilayer\nCrI$_3$ - Dzyaloshinskii-Moriya (DMI) and the Kitaev interaction (KI). We\ndevelop and apply a novel computational procedure that yields the off-diagonal\nexchange matrix elements with $\\mu$eV accuracy. Inspecting two types of bilayer\nstacking, we found a weak interlayer KI and much stronger DMI between the\nsublattices of monoclinic bilayer and their complete absence in rhombohedral\nbilayer. We show how these anisotropic interactions depend on the interlayer\ndistance, stacking sequence, and the spin-orbit coupling strength and suggest\nthe dominant superexchange processes at play. In addition, we demonstrate that\nthe single-ion anisotropy largely depends on stacking, increasing by 50% from\nmonoclinic to rhombohedral structure. Remarkably, our findings prove that\niodines, owing to their spatially extended 5p orbitals featuring strong\nspin-orbit coupling, are extremely efficient in mediating DMI across the van\nder Waals gap in two-dimensional magnetic heterostructures. Given that similar\nfindings were previously demonstrated only in metallic multilayers where the\nDMI shows a much longer range, our study gives promise that the chiral control\nof spin textures can be achieved in two-dimensional semiconducting magnetic\nbilayers whose ligands feature strong spin-orbit coupling.",
        "positive": "Probing the Structure and Energetics of Dislocation Cores in SiGe Alloys\n  through Monte Carlo Simulations: We present a methodology for the investigation of dislocation energetics in\nsegregated alloys based on Monte Carlo simulations which equilibrate the\ntopology and composition of the dislocation core and its surroundings. An\nenvironment-dependent partitioning of the system total energy into atomic\ncontributions allows us to link the atomistic picture to continuum elasticity\ntheory. The method is applied to extract core energies and radii of 60 degrees\nglide dislocations in segregated SiGe alloys which are inaccessible by other\nmethods."
    },
    {
        "anchor": "Second-order homogenization of periodic materials based on asymptotic\n  approximation of the strain energy: formulation and validity limits: In this paper a second-order homogenization approach for periodic material is\nderived from an appropriate representation of the down-scaling that correlates\nthe microdisplacement field to the macro-displacement field and the\nmacro-strain tensors involving unknown perturbation functions. These functions\ntake into account of the effects of the heterogeneities and are obtained by the\nsolution of properly defined recursive cell problems. Moreover, the\nperturbation functions and therefore the micro-displacement fields result to be\nsufficiently regular to guarantee the anti-periodicity of the traction on the\nperiodic unit cell. A generalization of the macro-homogeneity condition is\nobtained through an asymptotic expansion of the mean strain energy at the\nmicro-scale in terms of the microstructural characteristic size e; the obtained\noverall elastic moduli result to be not affected by the choice of periodic\ncell. The coupling between the macro- and microstress tensor in the periodic\ncell is deduced from an application of the generalised macrohomogeneity\ncondition applied to a representative portion of the heterogeneous material\n(cluster of periodic cell). The correlation between the proposed asymptotic\nhomogenization approach and the computational second-order homogenization\nmethods is obtained through an approximation of the macrodisplacement field\nbased on a second-order Taylor expansion. The form of the overall elastic\nmoduli obtained through the two homogenization approaches, here proposed, is\nanalyzed and the differences are highlighted.",
        "positive": "Quantum-Geometric Origin of Out-of-plane Stacking Ferroelectricity: Stacking ferroelectricity (SFE) has been discovered in a wide range of van\nder Waals materials and holds promise for applications, including photovoltaics\nand high-density memory devices. We show that the microscopic origin of\nout-of-plane stacking ferroelectric polarization can be generally understood as\na consequence of nontrivial Berry phase borne out of an effective\nSu-Schrieffer-Heeger model description with broken sublattice symmetry, thus\nelucidating the quantum-geometric origin of polarization in the extremely\nnon-periodic bilayer limit. Our theory applies to known stacking ferroelectrics\nsuch as bilayer transition-metal dichalcogenides in 3R and T$_{\\rm d}$ phases,\nas well as general AB-stacked honeycomb bilayers with staggered sublattice\npotential. Our explanatory and self-consistent framework based on the\nquantum-geometric perspective establishes quantitative understanding of\nout-of-plane SFE materials beyond symmetry principles."
    },
    {
        "anchor": "Designing transparent conductors using forbidden optical transitions: Many semiconductors present weak or forbidden transitions at their\nfundamental band gaps, inducing a widened region of transparency. This occurs\nin high-performing n-type transparent conductors (TCs) such as Sn-doped In2O3\n(ITO), however thus far the presence of forbidden transitions has been\nneglected in searches for new p-type TCs. To address this, we first compute\nhigh-throughput absorption spectra across ~18,000 semiconductors, showing that\nover half exhibit forbidden or weak optical transitions at their band edges.\nNext, we demonstrate that compounds with highly localized band edge states are\nmore likely to present forbidden transitions. Lastly, we search this set for\np-type and n-type TCs with forbidden or weak transitions. Defect calculations\nyield unexplored TC candidates such as ambipolar BeSiP2, Zr2SN2 and KSe, p-type\nBAs, Au2S, and AuCl, and n-type Ba2InGaO5, GaSbO4, and KSbO3, among others. We\nshare our data set via the MPContribs platform, and we recommend that future\nscreenings for optical properties use metrics representative of absorption\nfeatures rather than band gap alone.",
        "positive": "Analysis of optical differential transmission signals from\n  co-propagating fields in a lambda system medium: We analyze theoretically and experimentally how nonlinear\ndifferential-transmission spectroscopy of a lambda-system medium can provide\nquantitative understanding of the optical dipole moments and transition\nenergies. We focus on the situation where two optical fields spatially overlap\nand co-propagate to a single detector. Nonlinear interactions give\ncross-modulation between a modulated and non-modulated laser field, yielding\ndifferential transmission signals. Our analysis shows how this approach can be\nused to enhance the visibility of relatively weak transitions, and how\nparticular choices in the experimental design minimize systematic errors and\nthe sensitivity to changes in laser field intensities. Experimentally, we\ndemonstrate the relevance of our analysis with spectroscopy on the donor-bound\nexciton system of silicon donors in GaAs, where the transitions from the two\nbound-electron spin states to a bound-exciton state form a lambda system. Our\napproach is, however, of generic value for many spectroscopy experiments on\nsolid-state systems in small cryogenic measurement volumes where in-situ\nfrequency or polarization filtering of control and signal fields is often\nchallenging."
    },
    {
        "anchor": "Transition from a Tomonaga-Luttinger liquid to a Fermi liquid in\n  potassium intercalated bundles of single wall carbon nanotubes: We report on the first direct observation of a transition from a\nTomonaga-Luttinger liquid to a Fermi liquid behavior in potassium intercalated\nmats of single wall carbon nanotubes (SWCNT). Using high resolution\nphotoemission spectroscopy an analysis of the spectral shape near the Fermi\nlevel reveals a Tomonaga-Luttinger liquid power law scaling in the density of\nstates for the pristine sample and for low dopant concentration. As soon as the\ndoping is high enough to fill bands of the semiconducting tubes a distinct\ntransition to a bundle of only metallic SWCNT with a scaling behavior of a\nnormal Fermi liquid occurs. This can be explained by a strong screening of the\nCoulomb interaction between charge carriers and/or an increased hopping matrix\nelement between the tubes.",
        "positive": "Deterministic and stochastic models of dislocation patterning: We study a continuum model of dislocation transport in order to investigate\nthe formation of heterogeneous dislocation patterns. We propose a physical\nmechanism which relates the formation of heterogeneous patterns to the dynamics\nof a driven system which tries to minimize an internal energy functional while\nsubject to dynamic constraints and state dependent friction. This leads us to a\nnovel interpretation which resolves the old 'energetic vs. dynamic' controversy\nregarding the physical origin of dislocation patterns. We demonstrate the\nrobustness of the developed patterning scenario by considering the simplest\npossible case (plane strain, single slip) yet implementing the dynamics of the\ndislocation density evolution in two very different manners, namely (i) a\nhydrodynamic formulation which considers transport equations that are\ncontinuous in space and time while assuming a linear stress dependency of\ndislocation motion, and (ii) a stochastic cellular automaton implementation\nwhich assumes spatially and temporally discrete transport of discrete 'packets'\nof dislocation density which move according to an extremal dynamics. Despite\nthe huge differences between both kinds of models, we find that the emergent\npatterns are mutually consistent and in agreement with the prediction of a\nlinear stability analysis of the continuum model. We also show how different\ntypes of initial conditions lead to different intermediate evolution scenarios\nwhich, however, do not affect the properties of the fully developed patterns."
    },
    {
        "anchor": "Post density functional theoretical studies of highly polar\n  semiconductive Pb(Ti$_{1-x}$Ni$_{x}$)O$_{3-x}$ solid solutions: The effects\n  of cation arrangement on band gap: We use a combination of conventional density functional theory (DFT) and\npost-DFT methods, including the local density approximation plus Hubbard $U$\n(LDA+$U$), PBE0, and self-consistent $GW$ to study the electronic properties of\nNi-substituted PbTiO$_{3}$ (Ni-PTO) solid solutions. We find that LDA\ncalculations yield unreasonable band structures, especially for Ni-PTO solid\nsolutions that contain an uninterrupted NiO$_{2}$ layer. Accurate treatment of\nlocalized states in transition-metal oxides like Ni-PTO requires post-DFT\nmethods. $B$-site Ni/Ti cation ordering is also investigated. The $B$-site\ncation arrangement alters the bonding between Ni and O, and therefore strongly\naffects the band gap ($E_{\\rm g}$) of Ni-PTO. We predict that Ni-PTO solid\nsolutions should have a direct band gap in the visible light energy range, with\npolarization similar to the parent PbTiO$_{3}$. This combination of properties\nmake Ni-PTO solid solutions promising candidate materials for solar energy\nconversion devices.",
        "positive": "Electronic structure and magnetic exchange interactions of Cr-based van\n  der Waals ferromagnets. A comparative study between CrBr3 and Cr2Ge2Te6: Low dimensional magnetism has been powerfully boosted as a promising\ncandidate for numerous applications. The stability of the long-range magnetic\norder is directly dependent on the electronic structure and the relative\nstrength of the competing magnetic exchange constants. Here, we report a\ncomparative pressure-dependent theoretical and experimental study of the\nelectronic structure and exchange interactions of two-dimensional ferromagnets\nCrBr3 and Cr2Ge2Te6 . While CrBr3 is found to be a Mott-Hubbard-like insulator,\nCr2Ge2Te6 shows a charge-transfer character due to the broader character of the\nTe 5p bands at the Fermi level. This different electronic behaviour is\nresponsible of the robust insulating state of CrBr3 , in which the magnetic\nexchange constants evolve monotonically with pressure, and the proximity to a\nmetal-insulator transition predicted for Cr2Ge2Te6 , which causes a\nnon-monotonic evolution of its magnetic ordering temperature. We provide a\nmicroscopic understanding for the pressure evolution of the magnetic properties\nof the two systems."
    },
    {
        "anchor": "Pnictogens Allotropy and Phase Transformation during van der Waals\n  Growth: Pnictogens have multiple allotropic forms resulting from their ns2 np3\nvalence electronic configuration, making them the only elemental materials to\ncrystallize in layered van der Waals (vdW) and quasi-vdW structures throughout\nthe group. Light group VA elements are found in the layered orthorhombic A17\nphase such as black phosphorus, and can transition to the layered rhombohedral\nA7 phase at high pressure. On the other hand, bulk heavier elements are only\nstable in the A7 phase. Herein, we demonstrate that these two phases not only\nco-exist during the vdW growth of antimony on weakly interacting surfaces, but\nalso undertake a spontaneous transformation from the A17 phase to the\nthermodynamically stable A7 phase. This metastability of the A17 phase is\nrevealed by real-time studies unraveling its thickness-driven transition to the\nA7 phase and the concomitant evolution of its electronic properties. At a\ncritical thickness of ~4 nm, A17 antimony undergoes a diffusionless shuffle\ntransition from AB to AA stacked alpha-antimonene followed by a gradual\nrelaxation to the A7 bulk-like phase. Furthermore, the electronic structure of\nthis intermediate phase is found to be determined by surface self-passivation\nand the associated competition between A7- and A17-like bonding in the bulk.\nThese results highlight the critical role of the atomic structure and\ninterfacial interactions in shaping the stability and electronic\ncharacteristics of vdW layered materials, thus enabling a new degree of freedom\nto engineer their properties using scalable processes.",
        "positive": "Bulk High-Entropy Hexaborides: For the first time, a group of CaB6-typed cubic rare earth high-entropy\nhexaborides have been successfully fabricated into dense bulk pellets (>98.5%\nin relative densities). The specimens are prepared from elemental precursors\nvia in-situ metal-boron reactive spark plasma sintering. The sintered bulk\npellets are determined to be single-phase without any detectable oxides or\nother secondary phases. The homogenous elemental distributions have been\nconfirmed at both microscale and nanoscale. The Vickers microhardness are\nmeasured to be 16-18 GPa at a standard indentation load of 9.8 N. The\nnanoindentation hardness and Young's moduli have been measured to be 19-22 GPa\nand 190-250 GPa, respectively, by nanoindentation test using a maximum load of\n500 mN. The material work functions are determined to be 3.7-4.0 eV by\nultraviolet photoelectron spectroscopy characterizations, which are\nsignificantly higher than that of LaB6."
    },
    {
        "anchor": "MALTS: A tool to simulate Lorentz Transmission Electron Microscopy from\n  micromagnetic simulations: Here we describe the development of the MALTS software which is a generalised\ntool that simulates Lorentz Transmission Electron Microscopy (LTEM) contrast of\nthin magnetic nanostructures. Complex magnetic nanostructures typically have\nmultiple stable domain structures. MALTS works in conjunction with the open\naccess micromagnetic software Object Oriented Micromagnetic Framework or MuMax.\nMagnetically stable trial magnetisation states of the object of interest are\ninput into MALTS and simulated LTEM images are output. MALTS computes the\nmagnetic and electric phases accrued by the transmitted electrons via the\nAharonov-Bohm expressions. Transfer and envelope functions are used to simulate\nthe progression of the electron wave through the microscope lenses. The final\ncontrast image due to these effects is determined by Fourier Optics. Similar\napproaches have been used previously for simulations of specific cases of LTEM\ncontrast. The novelty here is the integration with micromagnetic codes via a\nsimple user interface enabling the computation of the contrast from any\nstructure. The output from MALTS is in good agreement with both experimental\ndata and published LTEM simulations. A widely-available generalized code for\nthe analysis of Lorentz contrast addresses is a much needed step towards the\nuse of LTEM as a standardized laboratory technique.",
        "positive": "Spontaneous Valley Splitting and Valley Pseudospin Field Effect\n  Transistor of Monolayer VAgP2Se6: Valleytronics is a rising topic to explore the emergent degree of freedom for\ncharge carriers in energy band edges and has attracted a great interest due to\nmany intriguing quantum phenomena and potential application in information\nprocessing industry. Creation of permanent valley polarization, i.e. unbalanced\noccupation at different valleys, is a chief challenge and also urgent question\nto be solved in valleytronics. Here we predict that the spin-orbit coupling and\nmagnetic ordering allow spontaneous valley Zeeman-type splitting in pristine\nmonolayer of VAgP2Se6 by using first-principles calculations. The Zeeman-type\nvalley splitting can lead to permanent valley polarization after suitable\ndoping. The Zeeman-type valley splitting is similar to the role of spin\npolarization in spintronics and is a vital requirement for practical devices in\nvalleytronics. The nonequivalent valleys of VAgP2Se6 monolayer can emit or\nabsorb circularly polarized photons with opposite chirality, and thus this\nmaterial shows a great potential to work as a photonic spin filter and\ncircularly-polarized-light resource. A valley pseudospin field effect\ntransistor (VPFET) is designed based on the monolayer VAgP2Se6 akin to the spin\nfield effect transistors. Beyond common transistors, VPFETs carry information\nof not only the electrons but also the valley pseudospins."
    },
    {
        "anchor": "An accurate scheme to solve cluster dynamics equations using a\n  Fokker-Planck approach: We present a numerical method to accurately simulate particle size\ndistributions within the formalism of rate equation cluster dynamics. This\nmethod is based on a discretization of the associated Fokker-Planck equation.\nWe show that particular care has to be taken to discretize the advection part\nof the Fokker-Planck equation, in order to avoid distortions of the\ndistribution due to numerical diffusion. For this purpose we use the\nKurganov-Noelle-Petrova scheme coupled with the monotonicity-preserving\nreconstruction MP5, which leads to very accurate results. The interest of the\nmethod is highlighted on the case of loop coarsening in aluminum. We show that\nthe choice of the models to describe the energetics of loops does not\nsignificantly change the normalized loop distribution, while the choice of the\nmodels for the absorption coefficients seems to have a significant impact on\nit.",
        "positive": "Direct and quasi-direct band gap silicon allotropes with remarkable\n  stability: In our present work, five previously proposed sp$^3$ carbon crystals were\nsuggested as silicon allotropes and their stabilities, electronic and optical\nproperties were investigated by first-principles method. We find that these\nallotropes with direct or quasi-direct band gaps in range of 1.2-1.6 eV are\nvery suitable for applications in thin-film solar cells. They display strong\nadsorption coefficients in the visible range of the sunlight in comparison with\ndiamond silicon. These five silicon allotropes are confirmed possessing\npositive dynamical stability and remarkable themodynamical stability close to\nthat of diamond silicon. Especially, the direct band gap M585-silicon\npossessing energy higher than diamond silicon only 25 meV per atom is expected\nto be experimentally produced for thin-film solar cells."
    },
    {
        "anchor": "Graphene defect formation by extreme ultraviolet generated\n  photoelectrons: We have studied the effect of photoelectrons on defect formation in graphene\nduring extreme ultraviolet (EUV) irradiation. Assuming the major role of these\nlow energy electrons, we have mimicked the process by using low energy primary\nelectrons. Graphene is irradiated by an electron beam with energy lower than 80\neV. After e-beam irradiation, it is found that the D peak, I(D), appears in the\nRaman spectrum, indicating defect formation in graphene. The evolution of\nI(D)/I(G) follows the amorphization trajectory with increasing irradiation\ndose, indicating that graphene goes through a transformation from\nmicrocrystalline to nanocrystalline and then further to amorphous carbon.\nFurther, irradiation of graphene with increased water partial pressure does not\nsignificantly change the Raman spectra, which suggests that, in the extremely\nlow energy range, e-beam induced chemical reactions between residual water and\ngraphene is not the dominant mechanism driving defect formation in graphene.\nSingle layer graphene, partially suspended over holes was irradiated with EUV\nradiation. By comparing with the Raman results from e-beam irradiation, it is\nconcluded that the photoelectrons, especially those from the valence band,\ncontribute to defect formation in graphene during irradiation.",
        "positive": "Steric engineering of metal-halide perovskites with tunable optical band\n  gaps: Owing to their high energy-conversion efficiency and inexpensive fabrication\nroutes, solar cells based on metal-organic halide perovskites have rapidly\ngained prominence as a disruptive technology. An attractive feature of\nperovskite absorbers is the possibility of tailoring their properties by\nchanging the elemental composition through the chemical precursors. In this\ncontext, rational in silico design represents a powerful tool for mapping the\nvast materials landscape and accelerating discovery. Here we show that the\noptical band gap of metal-halide perovskites, a key design parameter for solar\ncells, strongly correlates with a simple structural feature, the largest\nmetal-halide-metal bond angle. Using this descriptor we suggest continuous\ntunability of the optical gap from the mid-infrared to the visible. Precise\nband gap engineering is achieved by controlling the bond angles through the\nsteric size of the molecular cation. Based on these design principles we\npredict novel low-gap perovskites for optimum photovoltaic efficiency, and we\ndemonstrate the concept of band gap modulation by synthesising and\ncharacterising novel mixed-cation perovskites."
    },
    {
        "anchor": "Experimental Demonstration of a Structured Material with Extreme\n  Effective Parameters at Microwaves: Following our recent theoretical studies [M. G. Silveirinha, C. A. Fernandes,\nPhys. Rev. B, 78, 033108, 2008], it is experimentally verified that an array of\ncrossed metallic wires may behave as a nonresonant material with extremely\nlarge index of refraction at microwaves, and may enable the realization of\nultra-subwavelength waveguides.",
        "positive": "Automatic detection of equiaxed dendrites using computer vision neural\n  networks: Equaixed dendrites are frequently encountered in solidification. They\ntypically form in large numbers, which makes their detection, localization, and\ntracking practically impossible for a human eye. In this paper, we show how\nrecent progress in the field of machine learning can be leveraged to tackle\nthis problem and we present computer vision neural network to automatically\ndetect equiaxed dendrites. Our network is trained using phase-field simulation\nresults, and proper data augmentation allows to perform the detection task in\nsolidification conditions entirely different from those simulated for training.\nFor example, here we show how they can successfully detect dendrites of various\nsizes in a microgravity solidification experiment. We discuss challenges in\ntraining such a network along with our solutions for them, and compare the\nperformance of neural network with traditional methods of shapes detection."
    },
    {
        "anchor": "Spin diffusion in doped semiconductors: The behavior of spin diffusion in doped semiconductors is shown to be\nqualitatively different than in undoped (intrinsic) ones. Whereas a spin packet\nin an intrinsic semiconductor must be a multiple-band disturbance, involving\ninhomogeneous distributions of both electrons and holes, in a doped\nsemiconductor a single-band disturbance is possible. For n-doped nonmagnetic\nsemiconductors the enhancement of diffusion due to a degenerate electron sea in\nthe conduction band is much larger for these single-band spin packets than for\ncharge packets, and can exceed an order of magnitude at low temperatures even\nfor equilibrium dopings as small as 10^16 cm^-3. In n-doped ferromagnetic and\nsemimagnetic semiconductors the motion of spin packets polarized antiparallel\nto the equilibrium carrier spin polarization is predicted to be an order of\nmagnitude faster than for parallel polarized spin packets. These results are\nreversed for p-doped semiconductors.",
        "positive": "Lattice Thermal Transport in Two-Dimensional Alloys and Fractal\n  Heterostructures: Engineering thermal transport in two dimensional materials, alloys and\nheterostructures is critical for the design of next-generation flexible\noptoelectronic and energy harvesting devices. Direct experimental\ncharacterization of lattice thermal conductivity in these ultra-thin systems is\nchallenging and the impact of dopant atoms and hetero-phase interfaces,\nintroduced unintentionally during synthesis or as part of deliberate material\ndesign, on thermal transport properties is not understood. Here, we use\nnon-equilibrium molecular dynamics simulations to calculate lattice thermal\nconductivity of (Mo|W)Se$_2$ monolayer crystals including Mo$_{1-x}$W$_x$Se$_2$\nalloys with substitutional point defects, periodic MoSe$_2$|WSe$_2$\nheterostructures with characteristic length scales and scale-free fractal\nMoSe$_2$|WSe$_2$ heterostructures. Each of these features has a distinct effect\non phonon propagation in the crystal, which can be used to design fractal and\nperiodic alloy structures with highly tunable thermal conductivities. This\ncontrol over lattice thermal conductivity will enable applications ranging from\nthermal barriers to thermoelectrics."
    },
    {
        "anchor": "Accessing surface Brillouin zone and band structure of picene single\n  crystals: We have experimentally revealed the band structure and the surface Brillouin\nzone of insulating picene single crystals (SCs), the mother organic system for\na recently discovered aromatic superconductor, with ultraviolet photoelectron\nspectroscopy (UPS) and low-energy electron diffraction with laser for\nphotoconduction. A hole effective mass of 2.24 m_0 and the hole mobility mu_h\n>= 9.0 cm^2/Vs (298 K) were deduced in Gamma-Y direction. We have further shown\nthat some picene SCs did not show charging during UPS even without the laser,\nwhich indicates that pristine UPS works for high-quality organic SCs.",
        "positive": "Effects of Contrarians in the Minority Game: We study the effects of the presence of contrarians in an agent-based model\nof competing populations. Contrarians are common in societies. These\ncontrarians are agents who deliberately prefer to hold an opinion that is\ncontrary to the prevailing idea of the commons or normal agents. Contrarians\nare introduced within the context of the Minority Game (MG), which is a binary\nmodel for an evolving and adaptive population of agents competing for a limited\nresource. Results of numerical simulations reveal that the average success rate\namong the agents depends non-monotonically on the fraction $a_{c}$ of\ncontrarians. For small $a_{c}$, the contrarians systematically outperform the\nnormal agents by avoiding the crowd effect and enhance the overall success\nrate. For high $a_{c}$, the anti-persistent nature of the MG is disturbed and\nthe few normal agents outperform the contrarians. Qualitative discussion and\nanalytic results for the small $a_{c}$ and high $a_{c}$ regimes are also\npresented, and the crossover behavior between the two regimes is discussed."
    },
    {
        "anchor": "Ion Intercalation in Lanthanum Strontium Ferrite for Aqueous\n  Electrochemical Energy Storage Devices: Ion intercalation of perovskite oxides in liquid electrolytes is a very\npromising method for controlling their functional properties while storing\ncharge, which opens the potential application in different energy and\ninformation technologies. Although the role of defect chemistry in the oxygen\nintercalation in a gaseous environment is well established, the mechanism of\nion intercalation in liquid electrolytes at room temperature is poorly\nunderstood. In this study, the defect chemistry during ion intercalation of\nLa0.5Sr0.5FeO3-{\\delta} thin films in alkaline electrolytes is studied. Oxygen\nand proton intercalation into the LSF perovskite structure is observed at\nmoderate electrochemical potentials (0.5 V to -0.4 V), giving rise to a change\nin the oxidation state of Fe (as a charge compensation mechanism). The\nvariation of the concentration of holes as a function of the intercalation\npotential was characterized by in-situ ellipsometry and the concentration of\nelectron holes was indirectly quantified for different electrochemical\npotentials. Finally, a dilute defect chemistry model that describes the\nvariation of defect species during ionic intercalation was developed.",
        "positive": "Temperature dependence of the band gap shrinkage due to electron-phonon\n  interaction in undoped n-type GaN: The photoluminescence spectra of band-edge transitions in GaN is studied as a\nfunction of temperature. The parameters that describe the temperature\ndependence red-shift of the band-edge transition energy and the broadening of\nemission line are evaluated using different models. We find that the\nsemi-empirical relation based on phonon-dispersion related spectral function\nleads to excellent fit to the experimental data. The exciton-phonon coupling\nconstants are determined from the analysis of linewidth broadening."
    },
    {
        "anchor": "A New Group of Two-Dimensional Non-van der Waals Materials with Ultra\n  Low Exfoliation Energies: The exfoliation energy - quantifying the energy required to extract a\ntwo-dimensional (2D) sheet from the surface of a bulk material - is a key\nparameter determining the synthesizability of 2D compounds. Here, using ab\ninitio calculations, we present a new group of non-van der Waals 2D materials\nderived from non-layered crystals which exhibit ultra low exfoliation energies.\nIn particular for sulfides, surface relaxations are essential to correctly\ndescribe the associated energy gain needed to obtain reliable results. Taking\ninto account long-range dispersive interactions has only a minor effect on the\nenergetics and ultimately proves that the exfoliation energies are close to the\nones of traditional van der Waals bound 2D compounds. The candidates with the\nlowest energies, 2D SbTlO$_3$ and MnNaCl$_3$, exhibit appealing electronic,\npotential topological, and magnetic features as evident from the calculated\nband structures making these systems an attractive platform for fundamental and\napplied nanoscience.",
        "positive": "Improving photocatalytic activity of TiO$_2$ through reduction: The rutile TiO$_2$ (110) surface reduced by the bridging oxygen vacancy,\nbridging hydroxyl group or Ti interstitial atom has been investigated by\ncalculating their electronic structures using the density functional theory\nplus U method. It is found that defect states located in the forbidden band gap\ncan enhance optical absorption. When the surface is highly reduced, the defect\nstates approach the valence band. More importantly, defects induce a\nsubstantial up-shift of the conduction band edge, rendering the reduced surface\nstronger reducibility. The shifts of both conduction and valence band edges are\ndue to the dipole moments created by these defects."
    },
    {
        "anchor": "Gradient-enhanced statistical analysis of cleavage fracture: We present a probabilistic framework for brittle fracture that builds upon\nWeibull statistics and strain gradient plasticity. The constitutive response is\ngiven by the mechanism-based strain gradient plasticity theory, aiming to\naccurately characterize crack tip stresses by accounting for the role of\nplastic strain gradients in elevating local strengthening ahead of cracks. It\nis shown that gradients of plastic strain elevate the Weibull stress and the\nprobability of failure for a given choice of the threshold stress and the\nWeibull parameters. The statistical framework presented is used to estimate\nfailure probabilities across temperatures in ferritic steels. The framework has\nthe capability to estimate the three statistical parameters present in the\nWeibull-type model without any prior assumptions. The calibration against\nexperimental data shows important differences in the values obtained for strain\ngradient plasticity and conventional J2 plasticity. Moreover, local probability\nmaps show that potential damage initiation sites are much closer to the crack\ntip in the case of gradient-enhanced plasticity. Finally, the fracture response\nacross the ductile-to-brittle regime is investigated by computing the cleavage\nresistance curves with increasing temperature. Gradient plasticity predictions\nappear to show a better agreement with the experiments.",
        "positive": "Growth of Transition Metal Dichalcogenides by Solvent Evaporation\n  Technique: Due to their physical properties and potential applications in energy\nconversion and storage, transition metal dichalcogenides (TMDs) have garnered\nsubstantial interest in recent years. Amongst this class of materials, TMDs\nbased on molybdenum, tungsten, sulfur and selenium are particularly attractive\ndue to their semiconducting properties and the availability of bottom-up\nsynthesis techniques. Here we report a method which yields high quality\ncrystals of transition metal diselenide and ditelluride compounds (PtTe2,\nPdTe2, NiTe2, TaTe2, TiTe2, RuTe2, PtSe2, PdSe2, NbSe2, TiSe2, VSe2, ReSe2)\nfrom their solid solutions, via vapor deposition from a metal-saturated\nchalcogen melt. Additionally, we show the synthesis of rare-earth metal\npoly-chalcogenides and NbS2 crystals using the aforementioned process. Most of\nthe obtained crystals have a layered CdI2 structure. We have investigated the\nphysical properties of selected crystals and compared them to state-of-the-art\nfindings reported in the literature. Remarkably, the charge density wave\ntransition in 1T-TiSe2 and 2H-NbSe2 crystals is well-defined at TCDW ~ 200 K\nand ~ 33 K, respectively. Angle-resolved photoelectron spectroscopy and\nelectron diffraction are used to directly access the electronic and crystal\nstructures of PtTe2 single crystals, and yield state-of-the-art measurements."
    },
    {
        "anchor": "Electrical tuning of exciton-plasmon polariton coupling in monolayer\n  MoS2 integrated with plasmonic nanoantenna lattice: Active control of light-matter interactions in semiconductors is critical for\nrealizing next generation optoelectronic devices, with tunable control of the\nsystems optical properties via external fields. The ability to manipulate\noptical interactions in active materials coupled to cavities via geometrical\nparameters, which are fixed along with dynamic control with applied fields\nopens up possibilities of controlling exciton lifetimes, oscillator strengths\nand their relaxation properties. Here, we demonstrate electrical control of\nexciton-plasmon polariton coupling strength of a two-dimensional semiconductor\nintegrated with plasmonic nanoresonators assembled in a field-effect transistor\ndevice between strong and weak coupling limits by electrostatic doping. As a\nresult, the exciton-plasmon polarion dispersion can be altered dynamically with\napplied electric field by modulating the excitonic properties of monolayer MoS2\narising from many-body effects with carrier concentration. In addition, strong\ncoupling between charged excitons plasmons was also observed upon increased\ncarrier injection. The ability to dynamically control the optical properties of\nan ultra-thin semiconductor with plasmonic nanoresonators and electric fields\ndemonstrates the versatility of the coupled system and offers a new platform\nfor the design of optoelectronic devices with precisely tailored responses.",
        "positive": "A combined high-pressure experimental and theoretical study of the\n  electronic band-structure of scheelite-type AWO4 (A = Ca, Sr, Ba, Pb)\n  compounds: The optical-absorption edge of single crystals of CaWO4, SrWO4, BaWO4, and\nPbWO4 has been measured under high pressure up to ~20 GPa at room temperature.\nFrom the measurements we have obtained the evolution of the band-gap energy\nwith pressure. We found a low-pressure range (up to 7-10 GPa) where\nalkaline-earth tungstates present a very small Eg pressure dependence (-2.1 <\ndEg/dP < 8.9 meV/GPa). In contrast, in the same pressure range, PbWO4 has a\npressure coefficient of -62 meV/GPa. The high-pressure range is characterized\nin the four compounds by an abrupt decrease of Eg followed by changes in\ndEg/dP. The band-gap collapse is larger than 1.2 eV in BaWO4. We also\ncalculated the electronic-band structures and their pressure evolution.\nCalculations allow us to interpret experiments considering the different\nelectronic configuration of divalent metals. Changes in the pressure evolution\nof Eg are correlated with the occurrence of pressure-induced phase transitions.\nThe band structures for the low- and high-pressure phases are also reported. No\nmetallization of any of the compounds is detected in experiments nor is\npredicted by calculations."
    },
    {
        "anchor": "Using forces to accelerate first-principles anharmonic vibrational\n  calculations: High-level vibrational calculations have been used to investigate\nanharmonicity in a wide variety of materials using density-functional-theory\n(DFT) methods. We have developed a new and efficient approach for describing\nstrongly-anharmonic systems using a vibrational self-consistent-field (VSCF)\nmethod. By far the most computationally expensive part of the calculations is\nthe mapping of an accurate Born-Oppenheimer (BO) energy surface within the\nregion of interest. Here we present an improved method which reduces the\ncomputational cost of the mapping. In this approach we use data from a set of\nenergy calculations for different vibrational distortions of the materials and\nthe corresponding forces on the atoms. Results using both energies and forces\nare presented for the test cases of the hydrogen molecule, solid hydrogen under\nhigh pressure including mapping of two-dimensional subspaces of the BO surface,\nand the bcc phases of the metals Li and Zr. The use of forces data speeds up\nthe anharmonic calculations by up to 40%.",
        "positive": "Efficiency versus effort: a better way to compare best photovoltaic\n  research cell efficiencies?: Frequently, trends in record AM1.5 power-conversion efficiencies versus time,\nsuch as the NREL efficiency chart, are used to analyze the relative merits of\ndifferent photovoltaic material technologies. However, this approach belies the\neffort expended in achieving these levels of performance. We introduce\ncumulative publications as a proxy for total R&D efforts and find surprisingly\nthat silicon, Cu(In,Ga)Se2 (CIGSe), CdTe, and halide perovskite technologies\nhave each followed essentially the same learning curve of 20-24% efficiency\nwithin 10,000 publications and a consistent marginal rate of 5% efficiency\nincrease per factor of 10 in publications. While learning spillover from non-PV\ntechnologies, cross-pollination from other PV technologies, and hidden\ncommercial effort are not accounted for by this metric, this analysis still\nyields useful and novel insights into PV technology trajectories. Trajectories\nbelow this learning curve have required more total effort per performance and\nplateaus of efficiency stagnation at large numbers of publications may indicate\n(but do not guarantee) the existence of fundamental barriers to commercially\nrelevant performance. Lastly, examples to watch are identified for technologies\ncurrently exhibiting higher marginal slopes, including some that appeared\ndormant by this metric in past years."
    },
    {
        "anchor": "Introduction of spin centers in single crystals of\n  Ba$_2$CaWO$_{6-\u03b4}$: Developing the field of quantum information science (QIS) hinges upon\ndesigning viable qubits, the smallest unit in quantum computing. One approach\nto creating qubits is introducing paramagnetic defects into semiconductors or\ninsulators. This class of qubits has seen success in the form of\nnitrogen-vacancy centers in diamond, divacancy defects in SiC, and P doped into\nSi. These materials feature paramagnetic defects in a low nuclear spin\nenvironment to reduce the impact of nuclear spin on electronic spin coherence.\nIn this work, we report single crystal growth of Ba$_2$CaWO$_{6-\\delta}$, and\nthe coherence properties of controllably introduced W$^{5+}$ spin centers\ngenerated by oxygen vacancies. Ba$_2$CaWO$_{6-\\delta}$ ($\\delta$ = 0) is a\nB-site ordered double perovskite with a temperature-dependent octahedral\ntilting wherein oxygen vacancies generate W$^{5+}$ (d$^1$), $S = \\frac{1}{2},\nI$ = 0, centers. We characterized these defects by measuring the spin-lattice\n($T_1$) and spin-spin relaxation ($T_2$) times from T = 5 to 150 K. At T = 5 K,\n$T_1$ = 310 ms and $T_2$ = 4 $\\mu$s, establishing the viability of these qubit\ncandidates. With increasing temperature, $T_2$ remains constant up to T = 60 K\nand then decreases to $T_2$ $\\approx$ 1 $\\mu$s at T = 90 K, and remains roughly\nconstant until T = 150 K, demonstrating the remarkable stability of $T_2$ with\nincreasing temperature. Together, these results demonstrate that controlled\ndefect generation in double perovskite structures can generate viable\nparamagnetic point centers for quantum applications and expand the field of\npotential materials for QIS.",
        "positive": "Surface- and strain-tuning of the optical dielectric function in\n  epitaxially grown CaMnO3: We report a strong thickness dependence of the complex frequency-dependent\noptical dielectric function in epitaxial CaMnO3(001) thin films on SrTiO3(001),\nLaAlO3(001), and SrLaAlO4(001) substrates. A doubling of the peak value of the\nimaginary part of the dielectric function and spectral shifts of 0.5 eV for a\ngiven magnitude of absorption are observed. On the basis of the experimental\ndata and first-principles density functional theory calculations of the\ndielectric function, its evolution with thickness from 4 to 63 nm has several\nregimes. In the thinnest, strain-coherent films, the response is characterized\nby a significant contribution from the free surface that dominates strain\neffects. However, at intermediate and larger thicknesses approaching the\nbulk-like film, strain coherence and partial strain relaxation persist and in\ninfluence the dielectric function."
    },
    {
        "anchor": "Mechanisms for impulsive energy dissipation and small scale effects in\n  micro-granular media: We study impulse response in 1-D homogeneous micro-granular chains on a\nlinear elastic substrate. Micro-granular interactions are analytically\ndescribed by the Schwarz contact model which includes nonlinear compressive as\nwell as snap-to/from-contact adhesive effects forming a hysteretic loop in the\nforce deformation relationship. We observe complex transient dynamics,\nincluding disintegration of solitary pulses, local clustering and low- to\nhigh-frequency energy transfers resulting in enhanced energy dissipation. We\nstudy in detail the underlying dynamics of cluster formation in the impulsively\nloaded medium, and relate enhanced energy dissipation to the rate of cluster\nformation. These unusual and interesting dynamical phenomena are shown to be\nrobust over a range of physically feasible conditions, and are solely scale\neffects, since they are attributed to surface forces, which have no effect at\nthe macro-scale. We establish a universal relation between the re-clustering\nrate and the effective damping in these systems. Our findings demonstrate that\nscale effects generating new nonlinear features can drastically affect the\ndynamics and acoustics of micro-granular materials.",
        "positive": "Calorimetric study of multiaxial fluctuations in ferroelectric BaTiO3 in\n  nonpolar cubic phase: Precise specific heat of barium titanate single crystals of different quality\nhas been measured with special attention to the temperature region above the\nferroelectric phase transition. It is shown that excess specific heat of the\nmultiaxial barium titanate in the paraelectric phase has a fluctuation nature\nand its temperature dependence is in accordance with the theoretical\npredictions of Levanyuk theory for multiaxial ferroelectrics. In this study the\nfirst observation of fluctuation contribution to the specific heat is\npresented."
    },
    {
        "anchor": "From High-Entropy Ceramics (HECs) to Compositionally Complex Ceramics\n  (CCCs): This invited talk will review a series of our recent studies on high-entropy\nceramics (HECs) and compositionally complex ceramics (CCCs) and discuss the\nfuture perspective. Various single-phase equimolar quinary (five-component)\nHECs, e.g., MB2, MB, M3B4, MB4, and MB6 borides, MSi2 and M3Si5 silicides,\nperovskite, fluorite, and pyrochlore oxides, and (intermetallic) aluminides\nhave been fabricated. We further proposed to extend HECs to CCCs to include\nnon-equimolar compositions and further consider short- and long-range orders,\nwhich reduce configurational entropies but offer additional dimensions and\nopportunities to tailor and improve various properties. We also reported the\nfirst dual-phase HECs/CCCs. Using compositionally complex fluorite-based oxides\n(CCFBOs, which can possess fluorite or defect fluorite, pyrochlore, weberite,\nfergusonite, and bixbyite phases) as the model systems, we have recently\ndiscovered long- and short- range orders, composition- and redox-induced\norder-disorder transitions (ODTs), and ultrahigh-entropy weberite and\nfergusonite phases in several 10- to 21-component systems.",
        "positive": "Semiconductor Spintronics: Spintronics refers commonly to phenomena in which the spin of electrons in a\nsolid state environment plays the determining role. In a more narrow sense\nspintronics is an emerging research field of electronics: spintronics devices\nare based on a spin control of electronics, or on an electrical and optical\ncontrol of spin or magnetism. This review presents selected themes of\nsemiconductor spintronics, introducing important concepts in spin transport,\nspin injection, Silsbee-Johnson spin-charge coupling, and spindependent\ntunneling, as well as spin relaxation and spin dynamics. The most fundamental\nspin-dependent nteraction in nonmagnetic semiconductors is spin-orbit coupling.\nDepending on the crystal symmetries of the material, as well as on the\nstructural properties of semiconductor based heterostructures, the spin-orbit\ncoupling takes on different functional forms, giving a nice playground of\neffective spin-orbit Hamiltonians. The effective Hamiltonians for the most\nrelevant classes of materials and heterostructures are derived here from\nrealistic electronic band structure descriptions. Most semiconductor device\nsystems are still theoretical concepts, waiting for experimental\ndemonstrations. A review of selected proposed, and a few demonstrated devices\nis presented, with detailed description of two important classes: magnetic\nresonant tunnel structures and bipolar magnetic diodes and transistors. In most\ncases the presentation is of tutorial style, introducing the essential\ntheoretical formalism at an accessible level, with case-study-like\nillustrations of actual experimental results, as well as with brief reviews of\nrelevant recent achievements in the field."
    },
    {
        "anchor": "Oxygen vacancies in SrTiO$_{3}$ thin films at finite temperatures: A\n  first-principles study: Epitaxially grown SrTiO$_{3}$ (STO) thin films are material enablers for a\nnumber of critical energy-conversion and information-storage technologies like\nelectrochemical electrode coatings, solid oxide fuel cells and random access\nmemories. Oxygen vacancies (${\\rm V_{O}}$), on the other hand, are key defects\nto understand and tailor many of the unique functionalities realized in oxide\nperovskite thin films. Here, we present a comprehensive and technically sound\nab initio description of ${\\rm V_{O}}$ in epitaxially strained (001) STO thin\nfilms. The novelty of our first-principles study lies in the incorporation of\nlattice thermal excitations on the formation energy and diffusion properties of\n${\\rm V_{O}}$ over wide epitaxial strain conditions ($-4 \\le \\eta \\le +4$%). We\nfound that thermal lattice excitations are necessary to obtain a satisfactory\nagreement between first-principles calculations and the available experimental\ndata on the formation energy of ${\\rm V_{O}}$ for STO thin films. Furthermore,\nit is shown that thermal lattice excitations noticeably affect the energy\nbarriers for oxygen ion diffusion, which strongly depend on $\\eta$ and are\nsignificantly reduced (increased) under tensile (compressive) strain, also in\nconsistent agreement with the experimental observations. The present work\ndemonstrates that for a realistic theoretical description of oxygen vacancies\nin oxide perovskite thin films is necessary to consider lattice thermal\nexcitations, thus going beyond standard zero-temperature ab initio approaches.",
        "positive": "Multi Graphene Growth on Lead Pencil Drawn Sliver-Halide Print Paper\n  Irradiated by Scanning Femtosecond Laser: A variety of paper were drawn by lead pencil with the grade between 4H\nthrough 10B. Raman spectroscopy verified both G and D peaks on all the drawing\non PC print paper, PC photo paper, kent paper and paper for silver halide\nprint. After irradiation of scanning femtosecond laser, silver halide paper\ndrawn with 10B lead pencil remained surface flatness compared to the other\npapers. Raman spectroscopy on silver print paper showed a large G peak with\nless intensity of D peak. After irradiation of scanning femtosecond laser on\nsilver halide paper drawn by 10B lead pencil, Raman spectroscopy showed large G\npeak and less intensity of D peak together with 2D peak around 2,700 /cm\ncorresponding to the existence of multi graphene."
    },
    {
        "anchor": "Doping of Self-Standing CNT Fibers: Promising Flexible Air-Cathodes for\n  High Energy Density Structural Zn-air batteries: Finding proper electrocatalysts capable of efficient catalyzing both ORR and\nOER is of great importance for metal-air batteries. With increasing inclination\ntowards structural and flexible devices, developing a high-performance\nself-standing air-cathode is highly demanded and challenging, as most of oxygen\ncatalysts are powder and need to be further processed. Here, we construct\nhighly bifunctional air catalyst from macroscopic CNT fibers (CNTf) through\ndirect CVD spinning followed by hydrothermal method. The electrocatalytic\nproperties of the samples were tuned by altering nitrogen-doping and defect\ndensities readily adjusted at different hydrothermal reaction temperatures. The\ntreated CNTfs showed excellent bifunctional activity ({\\Delta}E=Ej=10-E1/2=0.81\nV) and demonstrated exceptional performance as carbon-based self-standing\nair-cathodes in liquid and solid-state rechargeable Zn-air batteries, with high\ncapacity of 698 mAh g-1 and ultrahigh energy density of 838 Wh kg-1. The\nrechargeable Zn-air batteries exhibit a low discharge-charge overpotential and\nexcellent stability. This work provides novel simply achieved self-standing air\nelectrodes with exceptional performance for structural Zn-air batteries.",
        "positive": "Electrically Engineered Band Gap in Two-Dimensional Ge, Sn, and Pb: A\n  First-Principles and Tight-Binding Approach: First-principles calculations were performed to investigate the electronic\nstructure of two-dimensional (2-D) Ge, Sn, and Pb without and with the presence\nof an external electric field in combination with spin-orbit coupling.\nTight-binding calculations based on four orbitals per atom and an effective\nsingle orbital are presented to match with the results obtained from\nfirst-principles calculations. In particular, the electronic band structure and\nthe band splitting are investigated with both models. Moreover, the simple\n$k\\cdot p$ model is also considered in order to understand the band splitting\nin the presence of an external electric field and spin-orbit coupling. A large\nsplitting is obtained, which is expected to be useful for spintronic devices.\nThe fair agreement between the first-principle, $k\\cdot p$ model, and\ntight-binding approaches leads to a table of parameters for future\ntight-binding studies on hexagonal 2-D nanostructures. By using the tight\nbinding parameters, the transport properties of typical 0-D triangular quantum\ndots between two semi-infinite electrodes in the presence of spin-orbit\ncoupling are addressed."
    },
    {
        "anchor": "Light Transition Metal Monatomic Chains: In this paper we investigated structural, electronic and magnetic properties\nof 3d (light) transition metal (TM) atomic chains using first-principles\npseudopotential plane wave calculations. Periodic linear, dimerized linear and\nplanar zigzag chain structures and their short segments consisting of finite\nnumber of atoms have been considered. Like Cu, the periodic, linear chains of\nMn, Co and Ni correspond to a local shallow minimum. However, for most of the\ninfinite periodic chains, neither linear nor dimerized linear structures are\nfavored; to lower their energy the chains undergo a structural transformation\nto form planar zigzag and dimerized zigzag geometry. Dimerization in both\ninfinite and finite chains are much stronger than the usual Peierls distortion\nand appear to depend on the number of 3d-electrons. As a result of\ndimerization, a significant energy lowering occurs which, in turn, influences\nthe stability and physical properties. Metallic linear chain of Vanadium\nbecomes half-metallic upon dimerization. Infinite linear chain of Scandium also\nbecomes half-metallic upon transformation to zigzag structure. An interplay\nbetween the magnetic ground state and atomic as well as electronic structure of\nthe chain has been revealed. The end effects influence the geometry, energetics\nand magnetic ground state of the finite chains. Structure optimization\nperformed using noncollinear approximation indicates significant differences\nfrom the collinear approximation. Variation of the cohesive energy of infinite\nand finite-size chains with respect to the number of 3d-electrons are found to\nmimic the bulk behavior pointed out by Friedel. The spin-orbit coupling of\nfinite chains are found to be negligibly small.",
        "positive": "Superposition of ferromagnetic and antiferromagnetic spin chains in the\n  quantum magnet BaAg2Cu[VO4]2: Based on density functional theory band structure calculations, quantum\nMonte-Carlo simulations, and high-field magnetization measurements, we address\nthe microscopic magnetic model of BaAg2Cu[VO4]2 that was recently proposed as a\nspin-1/2 anisotropic triangular lattice system. We show that the actual physics\nof this compound is determined by a peculiar superposition of ferromagnetic and\nantiferromagnetic uniform spin chains with nearest-neighbor exchange couplings\nof Ja(1) ~ -19 K and Ja(2) ~ 9.5 K, respectively. The two chains featuring\ndifferent types of the magnetic exchange perfectly mimic the specific heat of a\ntriangular spin lattice, while leaving a clear imprint on the magnetization\ncurve that is incompatible with the triangular-lattice model. Both\nferromagnetic and antiferromagnetic spin chains run along the crystallographic\n'a' direction, and slightly differ in the mutual arrangement of the magnetic\nCuO4 plaquettes and non-magnetic VO4 tetrahedra. These subtle structural\ndetails are, therefore, crucial for the ferromagnetic or antiferromagnetic\nnature of the exchange couplings, and put forward the importance of\ncomprehensive microscopic modeling for a proper understanding of quantum spin\nsystems in transition-metal compounds."
    },
    {
        "anchor": "Thermal transport across metal-insulator interface via electron-phonon\n  interaction: The thermal transport across metal-insulator interface can be characterized\nby electron-phonon interaction through which an electron lead is coupled to a\nphonon lead if phonon-phonon coupling at the interface is very weak. We\ninvestigate the thermal conductance and rectification flowing between the\nelectron part and the phonon part using nonequilibrium Green's function method.\nIt is found that the thermal conductance has a nonmonotonic behavior as a\nfunction of average temperature or the coupling strength between the phonon\nleads in the metal part and the insulator one. The metal-insulator interface\nshows evident thermal rectification effect, which can reverse with changing of\naverage temperature or the electron-phonon coupling.",
        "positive": "Wang tiles enable combinatorial design and robot-assisted manufacturing\n  of modular mechanical metamaterials: In this paper, we introduce a novel design paradigm for modular architectured\nmaterials that allows for spatially nonuniform designs from a handful of\nbuilding blocks, which can be robotically assembled for efficient and scalable\nproduction. The traditional, design-limiting periodicity in material design is\novercome by utilizing Wang tiles to achieve compatibility among building\nblocks. We illustrate our approach with the design and manufacturing of an\nL-shaped domain inspired by a scissor-like soft gripper, whose internal module\ndistribution was optimized to achieve an extreme tilt of a tip of the gripper's\njaw when the handle part was uniformly compressed. The geometry of individual\nmodules was built on a 3$\\times$3 grid of elliptical holes with varying\nsemi-axes ratios and alternating orientations. We optimized the distribution of\nthe modules within the L-shaped domain using an enumeration approach combined\nwith a factorial search strategy. To address the challenge of seamless\ninterface connections in modular manufacturing, we produced the final designs\nby casting silicone rubber into modular molds automatically assembled by a\nrobotic arm. The predicted performance was validated experimentally using a\ncustom-built, open-hardware test rig, Thymos, supplemented with digital image\ncorrelation measurements. Our study demonstrates the potential for enhancing\nthe mechanical performance of architectured materials by incorporating\nnonuniform modular designs and efficient robot-assisted manufacturing."
    },
    {
        "anchor": "Two components for one resistivity in LaVO3/SrTiO3 heterostructures: A series of 100 nm LaVO3 thin films have been synthesized on (001)-oriented\nSrTiO3 substrates using the pulsed laser deposition technique, and the effects\nof growth temperature are analyzed. Transport properties reveal a large\nelectronic mobility and a non-linear Hall effect at low temperature. In\naddition, a cross-over from a semiconducting state at high-temperature to a\nmetallic state at low-temperature is observed, with a clear enhancement of the\nmetallic character as the growth temperature increases. Optical absorption\nmeasurements combined with the two-bands analysis of the Hall effect show that\nthe metallicity is induced by the diffusion of oxygen vacancies in the SrTiO3\nsubstrate. These results allow to understand that the film/substrate\nheterostructure behaves as an original semiconducting-metallic parallel\nresistor, and electronic transport properties are consistently explained.",
        "positive": "Fitting the grain orientation distribution of a polycrystalline material\n  conditioned on a Laguerre tessellation: The description of distributions related to grain microstructure helps\nphysicists to understand the processes in materials and their properties. This\npaper presents a general statistical methodology for the analysis of\ncrystallographic orientations of grains in a 3D Laguerre tessellation dataset\nwhich represents the microstructure of a polycrystalline material. We introduce\ncomplex stochastic models which may substitute expensive laboratory\nexperiments: conditional on the Laguerre tessellation, we suggest interaction\nmodels for the distribution of cubic crystal lattice orientations, where the\ninteraction is between pairs of orientations for neighbouring grains in the\ntessellation. We discuss parameter estimation and model comparison methods\nbased on maximum pseudolikelihood as well as graphical procedures for model\nchecking using simulations. Our methodology is applied for analysing a dataset\nrepresenting a nickel-titanium shape memory alloy."
    },
    {
        "anchor": "Degeneracy of Ground State in Two-dimensional Electron-Lattice System: We discuss the ground state of a two dimensional electron-lattice system\ndescribed by a Su-Schrieffer-Heeger type Hamiltonian with a half-filled\nelectronic band, for which it has been pointed out in the previous paper [J.\nPhys. Soc. Jpn. 69 (2000) 1769-1776] that the ground state distortion pattern\nis not unique in spite of a unique electronic energy spectrum and the same\ntotal energy. The necessary and sufficient conditions to be satisfied by the\ndistortion patterns in the ground state are derived numerically. As a result\nthe degrees of degeneracy in the ground state is estimated to be about\n$N^{N/4}$ for $N \\gg 1$ with $N$ the linear dimension of the system.",
        "positive": "Coupled cluster theory in materials science: In this tutorial-style review we discuss basic concepts of coupled cluster\ntheory and recent developments that increase its computational efficiency for\ncalculations of molecules, solids and materials in general. We will touch upon\nthe connection between coupled cluster theory and the random-phase\napproximation that is widely used in the field of solid-state physics. We will\ndiscuss various approaches to improve the computational performance without\ncompromising on accuracy. These approaches include large-scale parallel design\nas well as techniques that reduce the pre-factor of the computational\ncomplexity. A central part of this article discusses the convergence of\ncalculated properties to the thermodynamic limit, which is of significant\nimportance for reliable predictions of materials properties and constitutes an\nadditional challenge compared to calculations of large molecules. We mention\ntechnical aspects of computer code implementations of periodic coupled cluster\ntheories in different numerical frameworks of the one-electron orbital basis;\nthe projector-augmented-wave formalism using a plane wave basis set and the\nnumeric atom-centered-orbital (NAO) with resolution-of-identity. We will\ndiscuss results and the possible scope of these implementations and how they\ncan help advance the current state of the art in electronic structure theory\ncalculations of materials."
    },
    {
        "anchor": "Formation of Monodispersed Cadmium Sulfide Particles by Aggregation of\n  Nanosize Precursors: Monodispersed spherical cadmium sulfide particles were used as a model system\nin order to explain the size selection in the formation of colloids by\naggregation of nanosize subunits. Several procedures of mixing the reactants\nwere employed to precipitate these solids and follow the kinetics of particle\ngrowth. Efficient numerical simulation techniques for the model rate equations\nwere developed to fit the experimental results. Our results have confirmed the\nrecently proposed mechanism of two-stage growth by nucleation of nanosize\ncrystalline primary particles and their subsequent aggregation into\npolycrystalline secondary colloids.",
        "positive": "First principles study of band line up at defective metal-oxide\n  interface: oxygen point defects at Al/SiO_2 interface: The dielectric breakdown at metal-oxide interfaces is a critical electronic\ndevice failure mechanism. Electronic tunneling through dielectric layers is a\nwell-accepted explanation for this phenomenon. Theoretical band alignment\nstudies, providing information about tunneling, have already been conducted in\nthe literature for metal-oxide interfaces. However, most of the time materials\nwere assumed defect free. Oxygen vacancies being very common in oxides, their\neffect on band lineup is of prime importance in understanding electron\ntunneling in realistic materials and devices. This work explores the effect of\noxygen vacancy and oxygen di-vacancy at the Al/SiO2 interface on the band line\nup within Density Functional Theory using PBE0 hybrid exchange and correlation\nfunctional. It is found that the presence of defects at the interface, and\ntheir charge state, strongly alters the band line up."
    },
    {
        "anchor": "Chaotic Crystallography: How the physics of information reveals\n  structural order in materials: We review recent progress in applying information- and computation-theoretic\nmeasures to describe material structure that transcends previous methods based\non exact geometric symmetries. We discuss the necessary theoretical background\nfor this new toolset and show how the new techniques detect and describe novel\nmaterial properties. We discuss how the approach relates to well known\ncrystallographic practice and examine how it provides novel interpretations of\nfamiliar structures. Throughout, we concentrate on disordered materials that,\nwhile important, have received less attention both theoretically and\nexperimentally than those with either periodic or aperiodic order.",
        "positive": "Identification of spin wave modes strongly coupled to a co-axial cavity: We demonstrate, at room temperature, the strong coupling of the fundamental\nand non-uniform magnetostatic modes of an yttrium iron garnet (YIG)\nferrimagnetic sphere to the electromagnetic modes of a co-axial cavity. The\nwell-defined field profile within the cavity yields a specific coupling\nstrength for each magnetostatic mode. We experimentally measure the coupling\nstrength for the different magnetostatic modes and, by calculating the expected\ncoupling strengths, are able to identify the modes themselves."
    },
    {
        "anchor": "A powered full quantum eigensolver for energy band structures: There has been an increasing research focus on quantum algorithms for\ncondensed matter systems recently, particularly on calculating energy band\nstructures. Here, we propose a quantum algorithm, the powered full quantum\neigensolver(P-FQE), by using the exponentiation of operators of the full\nquantum eigensolver(FQE). This leads to an exponential increase in the success\nprobability of measuring the target state in certain circumstances where the\nnumber of generating elements involved in the exponentiation of operators\nexhibit a log polynomial dependence on the number of orbitals. Furthermore, we\nconduct numerical calculations for band structure determination of the twisted\ndouble-layer graphene. We experimentally demonstrate the feasibility and\nrobustness of the P-FQE algorithm using superconducting quantum computers for\ngraphene and Weyl semimetal. One significant advantage of our algorithm is its\nability to reduce the requirements of extremely high-performance hardware,\nmaking it more suitable for energy spectra determination on noisy\nintermediate-scale quantum (NISQ) devices.",
        "positive": "Mechanisms of Electromechanical Coupling in Strain Based Scanning Probe\n  Microscopy: Electromechanical coupling is ubiquitous in nature and underpins the\nfunctionality of materials and systems as diverse as ferroelectric and\nmultiferroic materials, electrochemical devices, and biological systems, and\nstrain-based scanning probe microscopy (s-SPM) techniques have emerged as a\npowerful tool in characterizing and manipulating electromechanical coupling at\nthe nanoscale. Uncovering underlying mechanisms of electromechanical coupling\nin these diverse materials and systems, however, is a difficult outstanding\nproblem, and questions and confusions arise from recent experiment observations\nof electromechanical coupling and its apparent polarity switching in some\nunexpected materials. We propose a series of s-SPM experiments to identify\ndifferent microscopic mechanisms underpinning electromechanical coupling, and\ndemonstrate their feasibility using three representative materials. By\nemploying a combination of spectroscopic studies and different modes of s-SPM,\nwe show that it is possible to distinguish electromechanical coupling arising\nfrom spontaneous polarization, induced dipole moment, and ionic Vegard strain,\nand this offer a clear guidance on using s-SPM to study a wide variety of\nfunctional materials and systems."
    },
    {
        "anchor": "Biexciton fine structure in monolayer transition metal dichalcogenides: The optical properties of atomically thin transition metal dichalcogenide\n(TMDC) semiconductors are shaped by the emergence of correlated many-body\ncomplexes due to strong Coulomb interaction. Exceptional electron-hole exchange\npredestines TMDCs to study fundamental and applied properties of Coulomb\ncomplexes such as valley depolarization of excitons and fine-structure\nsplitting of trions. Biexcitons in these materials are less understood and it\nhas been established only recently that they are spectrally located between\nexciton and trion.\n  Here we show that biexcitons in monolayer TMDCs exhibit a distinct fine\nstructure on the order of meV due to electron-hole exchange. Ultrafast\npump-probe experiments on monolayer WSe$_2$ reveal decisive biexciton\nsignatures and a fine structure in excellent agreement with a microscopic\ntheory. We provide a pathway to access biexciton spectra with unprecedented\naccuracy, which is valuable beyond the class of TMDCs, and to understand even\nhigher Coulomb complexes under the influence of electron-hole exchange.",
        "positive": "Electron-phonon coupling in crystalline Pentacene films: The electron-phonon(e-p) interaction in Pentacene (Pn) films grown on Bi(001)\nwas investigated using photoemission spectroscopy. The spectra reveal thermal\nbroadening from which we determine an e-p mass enhancement factor of lambda =\n0.36 +/- 0.05 and an effective Einstein energy of omega_E = 11 +/- 4 meV. From\nomega_E it is inferred that dominant contributions to the e-p effects observed\nin ARPES come from intermolecular vibrations. Based on the experimental data\nfor lambda we extract an effective Peierls coupling value of g_eff = 0.55. The\ne-p coupling narrows the HOMO band width by 15 +/- 8% between 75K and 300K."
    },
    {
        "anchor": "Asymmetric magnetism at the interfaces of MgO/FeCoB bilayers by\n  exchanging the order of MgO and FeCoB: Interfaces in FeCoB/MgO/FeCoB magnetic tunnel junction play a vital role in\ncontrolling their magnetic and transport properties for various applications in\nspintronics and magnetic recording media. In this work, interface structures of\na few nm thick FeCoB layers in FeCoB/MgO and MgO/FeCoB bilayers are\ncomprehensively studied using x-ray standing waves (XSW) generated by\ndepositing bilayers between Pt waveguide structures. High interface selectivity\nof nuclear resonance scattering (NRS) under the XSW technique allowed measuring\nstructure and magnetism at the two interfaces, namely FeCoB-on-MgO and\nMgO-on-FeCoB, yielding an interesting result that electron density and\nhyperfine fields are not symmetric at both interfaces. The formation of a\nhigh-density FeCoB layer at the MgO/FeCoB (FeCoB-on-MgO) interface with an\nincreased hyperfine field (~34.65 T) is attributed to the increasing volume of\nFeCo at the interface due to boron diffusion from 57FeCoB to the MgO layer.\nFurthermore, it caused unusual angular-dependent magnetic properties in\nMgO/FeCoB bilayer, whereas FeCoB/MgO is magnetically isotropic. In contrast to\nthe literature, where the unusual angular dependent in FeCoB based system is\nexplained in terms of in-plane magnetic anisotropy, present findings attributed\nthe same to the interlayer exchange coupling between bulk and interface layer\nwithin the FeCoB layer.",
        "positive": "Scaling properties of granular materials: Given an assembly of viscoelastic spheres with certain material properties,\nwe raise the question how the macroscopic properties of the assembly will\nchange if all lengths of the system, i.e. radii, container size etc., are\nscaled by a constant. The result leads to a method to scale down experiments to\nlab-size."
    },
    {
        "anchor": "Single Crystal Functional Oxides on Silicon: Single crystalline thin films of complex oxides show a rich variety of\nfunctional properties such as ferroelectricity, piezoelectricity, ferro and\nantiferromagnetism etc. that have the potential for completely new electronic\napplications (1-2). Direct synthesis of such oxides on Si remains challenging\ndue to the fundamental crystal chemistry and mechanical incompatibility of\ndissimilar interfaces (3-16). Here we report integration of thin (down to 1\nunit cell) single crystalline, complex oxide films onto Si substrates, by\nepitaxial transfer at room temperature. In a field effect transistor using a\ntransferred Pb0.2Zr0.8TiO3 (PZT) layer as the gate insulator, we demonstrate\ndirect reversible control of the semiconductor channel charge with polarization\nstate. These results represent the realization of long pursued but yet to be\ndemonstrated single crystal functional oxides on-demand on silicon.",
        "positive": "Two-dimensional metal-chalcogenide films in tunable optical\n  microcavities: Quasi-two-dimensional (2D) films of layered metal-chalcogenides have\nattractive optoelectronic properties. However, photonic applications of thin\nfilms may be limited owing to weak light absorption and surface effects leading\nto reduced quantum yield. Integration of 2D films in optical microcavities will\npermit these limitations to be overcome owing to modified light coupling with\nthe films. Here we present tunable microcavities with embedded monolayer MoS2\nor few monolayer GaSe films. We observe significant modification of spectral\nand temporal properties of photoluminescence (PL): PL is emitted in spectrally\nnarrow and wavelength-tunable cavity modes with quality factors up to 7400; PL\nlife-time shortening by a factor of 10 is achieved, a consequence of Purcell\nenhancement of the spontaneous emission rate. This work has potential to pave\nthe way to microcavity-enhanced light-emitting devices based on layered 2D\nmaterials and their heterostructures, and also opens possibilities for cavity\nQED in a new material system of van der Waals crystals."
    },
    {
        "anchor": "Probing the Atomic Arrangement of Sub-Surface Dopants in a Silicon\n  Quantum Device Platform: High-density structures of sub-surface phosphorus dopants in silicon continue\nto garner interest as a silicon-based quantum computer platform, however, a\nmuch-needed confirmation of their dopant arrangement has been lacking. In this\nwork, we take advantage of the chemical specificity of X-ray photoelectron\ndiffraction to obtain the precise structural configuration of P dopants in\nsub-surface Si:P $\\delta$-layers. The growth of $\\delta$-layer systems with\ndifferent levels of doping is carefully studied and verified using X-ray\nphotoelectron spectroscopy and low-energy electron diffraction. Subsequent XPD\nmeasurements reveal that in all cases, the dopants primarily substitute with Si\natoms from the host material. Furthermore, no signs of free carrier-inhibiting\nP$-$P dimerization can be observed. Our observations not only settle a nearly\ndecade-long debate about the dopant arrangement but also demonstrate that XPD\nis well suited to study sub-surface dopant structures. This work thus provides\nvaluable input for an updated understanding of the behavior of Si:P\n$\\delta$-layers and the modeling of their derived quantum devices.",
        "positive": "Electron spin relaxation in bulk III-V semiconductors from a fully\n  microscopic kinetic spin Bloch equation approach: Electron spin relaxation in bulk III-V semiconductors is investigated from a\nfully microscopic kinetic spin Bloch equation approach where all relevant\nscatterings, such as, the electron--nonmagnetic-impurity, electron-phonon,\nelectron-electron, electron-hole, and electron-hole exchange (the\nBir-Aronov-Pikus mechanism) scatterings are explicitly included. The\nElliot-Yafet mechanism is also fully incorporated. This approach offers a way\ntoward thorough understanding of electron spin relaxation both near and far\naway from the equilibrium in the metallic regime. The dependence of the spin\nrelaxation time on electron density, temperature, initial spin polarization,\nphoto-excitation density, and hole density are studied thoroughly with the\nunderlying physics analyzed. In contrast to the previous investigations in the\nliterature, we find that: (i) In $n$-type materials, the Elliot-Yafet mechanism\nis {\\em less} important than the D'yakonov-Perel' mechanism, even for the\nnarrow band-gap semiconductors such as InSb and InAs. (ii) The density\ndependence of the spin relaxation time is nonmonotonic and we predict a {\\em\npeak} in the metallic regime in both $n$-type and intrinsic materials. (iii) In\nintrinsic materials, the Bir-Aronov-Pikus mechanism is found to be negligible\ncompared with the D'yakonov-Perel' mechanism. We also predict a peak in the\ntemperature dependence of spin relaxation time which is due to the nonmonotonic\ntemperature dependence of the electron-electron Coulomb scattering in intrinsic\nmaterials with small initial spin polarization. (iv) In $p$-type III-V\nsemiconductors, ...... (the remaining is omitted here due to the limit of\nspace)"
    },
    {
        "anchor": "Electrical and optical properties of ITO thin films prepared by DC\n  magnetron sputtering for low-emitting coatings: Optimized DC magnetron sputtering system for the deposition of transparent\nconductive oxides (TCOs), such indium tin oxide (ITO) on glass substrate has\nbeen applied in order to achieve low-emitting (low-e) transparent coatings. To\nobtain the concerned electrical resistance and high infrared reflection, first\nthe effect of applied sputtering power then oxygen flow on the properties of\nfilms have been investigated. The other depositions parameters are kept\nconstant. Film deposition at at temperature 400 degree of Celsius in oxygen\nflow of 3 Standard Cubic Centimeters per Minute results in transparent and\ninfrared reflecting coatings. Under this condition the highest attained average\nreflectance in the infrared is ({\\lambda}=3-25 micron) 89.5% (lowest emittance\nequals to less than 11%), whereas transparency in the visible is 85%\napproximately. Plasma wavelength and carrier concentration was measured.",
        "positive": "A New Synthesis Approach for Carbon Nitrides: Poly (Triazine Imide) and\n  Its Photocatalytic Properties: Poly (triazine imide) (PTI) is a material belonging to the group of carbon\nnitrides and has shown to have competitive properties compared to melon or\ng-C3N4, especially in photocatalysis. As most of the carbon nitrides PTI is\nusually synthesized by thermal or hydrothermal approaches. We present and\ndiscuss an alternative synthesis for PTI which exhibits a pH dependent\nsolubility in aqueous solutions. This synthesis is based on the formation of\nradicals during electrolysis of an aqueous melamine solution, coupling of\nresulting melamine radicals and the final formation of PTI. We applied\ndifferent characterization techniques to identify PTI as the product of this\nreaction and report the first liquid state NMR experiments on a triazine-based\ncarbon nitride. We show that PTI has a relatively high specific surface area\nand a pH dependent adsorption of charged molecules. This tunable adsorption has\na significant influence on the photocatalytic properties of PTI which we\ninvestigated in dye degradation experiments."
    },
    {
        "anchor": "A probabilistic model of the electron transport in films of PbSe\n  nanocrystals arranged in a cubic lattice: The fabrication of nanocrystal (NC) films, starting from colloidal\ndispersion, is a very attractive topic in condensed matter physics community.\nNC films can be employed for transistors, light emitting diodes, laser, and\nsolar cells. For this reason the understanding of the film conductivity is of\nmajor importance. In this paper we describe a probabilistic model that allow to\npredict the conductivity of the NC films, in this case of a cubic lattice of\nLead Selenide NCs. The model is based on the hopping probability between NCs\nshow a comparison with experimental data reported in literature.",
        "positive": "Characterization of Thin Film Materials using SCAN meta-GGA, an Accurate\n  Nonempirical Density Functional: We discuss self-consistently obtained ground-state electronic properties of\nmonolayers of graphene and a number of beyond graphene compounds, including\nfilms of transition-metal dichalcogenides (TMDs), using the recently proposed\nstrongly constrained and appropriately normed (SCAN) meta-generalized gradient\napproximation (meta-GGA) to the density functional theory. The SCAN meta-GGA\nresults are compared with those based on the local density approximation (LDA)\nas well as the generalized gradient approximation (GGA). As expected, the GGA\nyields expanded lattices and softened bonds in relation to the LDA, but the\nSCAN meta-GGA systematically improves the agreement with experiment. Our study\nsuggests the efficacy of the SCAN functional for accurate modeling of\nelectronic structures of layered materials in high-throughput calculations more\ngenerally."
    },
    {
        "anchor": "Effect of $R$-site substitution and the pressure on stability of\n  $R$Fe$_{12}$: A first-principles study: We theoretically study the structural stability of $R$Fe$_{12}$ with the\nThMn$_{12}$ structure ($R$: rare-earth elements, La, Pr, Nd, Sm, Gd, Dy, Ho,\nEr, Tm, Lu, Y, or Sc, or group-IV elements, Zr or Hf) based on density\nfunctional theory. The formation energy has a strong correlation with the\natomic radius of $R$. The formation energy relative to simple substances\ndecreases as the atomic radius decreases, except for $R=$ Sc and Hf, while that\nrelative to $R_{2}$Fe$_{17}$ and bcc Fe has a minimum for $R=$ Dy. The present\nresults are consistent with recent experimental reports in which the partial\nsubstitution of Zr at $R$ sites stabilizes $R$Fe$_{12}$-type compounds with\n$R=$ Nd or Sm. Our results also suggest that the partial substitution of Y, Dy,\nHo, Er, or Tm for Nd or Sm is a possible way to enhance the stability of the\nThMn$_{12}$ structure. Under hydrostatic pressure, the formation enthalpy\ndecreases up to $\\approx$ 6 GPa and then starts to increase at higher\npressures.",
        "positive": "New discrete method for investigating the response properties in finite\n  electric field: In this paper we develop a new discrete method for calculating the dielectric\ntensor and Born effective charge tensor in finite electric field by using\nBerry's phase and the gauge invariance. We present a new method to overcome\nnon-periodicity of the potential in finite electric field due to the gauge\ninvariance, and construct the dielectric tensor and Born effective charge\ntensor that satisfy translational symmetry in finite electric field. In order\nto demonstrate the correctness of this method, we also perform calculations for\nthe semiconductors AlAs and GaAs under the finite electric field to compare\nwith the preceding method and the experiment."
    },
    {
        "anchor": "Conversion of La$_2$Ti$_2$O$_7$ to LaTiO$_2$N via Ammonolysis: An\n  ab-initio Investigation: Perovskite oxynitrides are, due to their reduced band gap compared to oxides,\npromising materials for photocatalytic applications. They are most commonly\nsynthesized from {110} layered Carpy-Galy (A$_2$B$_2$O$_7$}) perovskites via\nthermal ammonolysis, i.e. the exposure to a flow of ammonia at elevated\ntemperature. The conversion of the layered oxide to the non-layered oxynitride\nmust involve a complex combination of nitrogen incorporation, oxygen removal\nand ultimately structural transition by elimination of the interlayer shear\nplane. Despite the process being commonly used, little is known about the\nmicroscopic mechanisms and hence factors that could ease the conversion. Here\nwe aim to derive such insights via density functional theory calculations of\nthe defect chemistry of the oxide and the oxynitride as well as the oxide's\nsurface chemistry. Our results point to the crucial role of surface oxygen\nvacancies in forming clusters of NH$_3$ decomposition products and in\nincorporating N, most favorably substitutionally at the anion site. N then\nspontaneously diffuses away from the surface, more easily parallel to the\nsurface and in interlayer regions, while diffusion perpendicular to the\ninterlayer plane is somewhat slower. Once incorporation and diffusion lead to a\nlocal N concentration of about 70% of the stoichiometric oxynitride\ncomposition, the nitridated oxide spontaneously transforms to a\nnitrogen-deficient oxynitride.",
        "positive": "Magnetic reversal and pinning in a perpendicular zero moment half-metal: Compensated ferrimagnets are promising materials for fast spintronic\napplications based on domain wall motion as they combine the favourable\nproperties of ferromagnets and antiferromagnets. They inherit from\nantiferromagnets immunity to external fields, fast spin dynamics and rapid\ndomain wall motion. From ferromagnets they inherit straightforward ways to read\nout the magnetic state, especially in compensated half metals, where electrons\nflow in only one spin channel. Here, we investigate domain structure in\ncompensated half-metallic Mn2Ru0.5Ga films and assess their potential in domain\nwall motion-based spin-electronic devices. Our focus is on understanding and\nreducing domain wall pinning in unpatterned epitaxial thin films. Two modes of\nmagnetic reversal, driven by nucleation or domain wall motion, are identified\nfor different thin film deposition temperatures $(T_{dep})$. The magnetic\naftereffect is analysed to extract activation volumes $(V^*)$, activation\nenergies $(E_A)$, and their variation $({\\Delta}E_A)$. The latter is decisive\nfor the magnetic reversal regime, where domain wall motion dominated reversal\n(weak pinning) is found for ${\\Delta}E_A<0.2$ eV and nucleation dominated\nreversal (strong pinning) for ${\\Delta}E_A>0.5$ eV. A minimum ${\\Delta}E_A=28$\nmeV is found for $T_{dep}=290{\\deg}$C. Prominent pinning sites are visualized\nby analysing virgin domain patterns after thermal demagnetization. In the\nsample investigated they have spacings of order 300 nm, which gives an upper\nlimit of the track-width of spin-torque domain-wall motion-based devices."
    },
    {
        "anchor": "Thermodynamic properties for metal oxides from first-principles: In this study, an efficient first-principles approach for calculating the\nthermodynamic properties of mixed metal oxides at high temperatures is\ndemonstrated. More precisely, this procedure combines density functional theory\nand harmonic phonon calculations with tabulated thermochemical data to predict\nthe heat capacity, formation energy, and entropy of important metal oxides.\nAlloy cluster expansions are, moreover, employed to represent phases that\ndisplay chemical ordering as well as to calculate the configurational\ncontribution to the specific heat capacity. The methodology can, therefore, be\napplied to compounds with vacancies and variable site occupancies. Results are,\nmoreover, presented for a number of systems of high practical relevance:\nFe-K-Ti-O, K-Mn-O, and Ca-Mn-O. In the case of ilmenite (FeTiO3), the agreement\nwith experimental measurements is exceptionally good. When the generated data\nis used in multi-phase thermodynamic calculations to represent materials for\nwhich experimental data is not available, the predicted phase-diagrams for the\nK-Mn-O and K-Ti-O systems change dramatically. The demonstrated methodology is\nhighly useful for obtaining approximate values on key thermodynamic properties\nin cases where experimental data is hard to obtain, inaccurate or missing.",
        "positive": "The Hypergraphite: A possible extension of graphitic network: We propose a class of networks which can be regarded as an extension of the\ngraphitic network. These networks are constructed so that surface states with\nnon-bonding character (edge states) are formed in a tight-binding model with\none orbital for each atomic site. Besides, for several networks, the\ntight-binding electronic structures become a zero-gap semiconductor. These\nproperties have been found in the $\\pi$-electron system of the graphene. Thus,\nwe call these networks hypergraphite."
    },
    {
        "anchor": "Optical properties of Er3+ doped alkali-chloro phosphate glasses for\n  optical amplifiers: A new class of Erbium doped glasses with compositions xNa2O - (60-x)PbCl2 -\n40P2O5 (x=0, 10, 20 and 30) were fabricated and characterized for optical\nproperties. Absorption spectra were analyzed for important Judd-Ofelt\nparameters from the integrated intensities of various Er3+ glass absorption\nbands. Photoluminescence (PL) and its decay behavior studies were carried out\nfor the transition 4I13/2 -> 4I15/2. A systematic correlation between the\nJudd-Ofelt parameter {omega}2 and the covalent nature of the glass matrix was\nobserved, due to increased role of bridging oxygens in the glass network. The\nPL broadness and life times of 4I13/2_> 4I15/2 transition were typically in the\nrange of 40-60nm and 2.13-2.5ms respectively. These glasses broadly showed high\ntransparency, high refractive index, shorter life times and, most importantly,\nthese glasses were found to be capable of being doped with larger\nconcentrations of Er3+ (up to 4 wt%). Increase of Er3+ concentration resulted\nin the increase in PL line-widths with no significant effect of concentration\nquenching, indicating that these glasses are suitable for optical\nfibre/waveguide amplifiers.",
        "positive": "Lone pairs in insulating pyrochlores: Ice rules and high-$k$ behavior: Pyrochlore dielectric materials such as\n(Bi$_{1.5}$Zn$_{0.5}$)(Nb$_{1.5}$Zn$_{0.5}$)O$_7$ (BZN) have generated interest\nbecause they combine high dielectric constants with small dielectric loss\ntangents and yet are cubic at all temperatures. The recent low-temperature\npreparation and structural characterization of Bi$_2$Ti$_2$O$_7$, which remains\ncubic down to 2 K, has provided a good model system for understanding the\nproperties of Bi-based pyrochlores. In this contribution, the electronic\nstructure of cubic Bi$_2$Ti$_2$O$_7$ is visualized and compared with the\nelectronic structure of the Aurivillius phase ferroelectric SrBi$_2$Ta$_2$O$_9$\n(SBT), which displays a ferroelectric distortion below 608 K associated with\nthe tendency of lone pair active Bi$^{3+}$ to move off-center. Such coherent\noff-centering distortions are frustrated on the pyrochlore lattice, and this\nprevents a ferroelectric-paraelectric phase transition in Bi$_2$Ti$_2$O$_7$.\nInstead, Bi$^{3+}$ ions in Bi$_2$Ti$_2$O$_7$ are obliged to off-center in an\n\\textit{incoherent} manner, that is compatible with the cubic structure being\nretained. Frustrated lone pair behavior in the defect pyrochlore\nPb$_2$Sn$_2$O$_6$ is also described. Parallels between the well-studied\nfrustration of certain types of \\textit{magnetism} in pyrochlore compounds\n(spin-ice) and the striking paucity of ferroelectric pyrochlores, arising from\nthe corner-connected tetrahedral topology of the pyrochlore lattice are pointed\nout."
    },
    {
        "anchor": "The effect of the substrate on the Raman and photoluminescence emission\n  of single layer MoS2: We quantitatively study the Raman and photoluminescence (PL) emission from\nsingle layer molybdenum disulfide (MoS2) on dielectric (SiO2, hexagonal boron\nnitride, mica and the polymeric dielectric Gel-Film) and conducting substrates\n(Au and few-layer graphene). We find that the substrate can affect the Raman\nand PL emission in a twofold manner. First, the absorption and emission\nintensities are strongly modulated by the constructive/destructive interference\nwithin the different substrates. Second, the position of the A1g Raman mode\npeak and the spectral weight between neutral and charged excitons in the PL\nspectra are modified by the substrate. We attribute this effect to\nsubstrate-induced changes in the doping level and in the decay rates of the\nexcitonic transitions. Our results provide a method to quantitatively study the\nRaman and PL emission from MoS2-based vertical heterostructures and represent\nthe first step in ad-hoc tuning the PL emission of 1L MoS2 by selecting the\nproper substrate.",
        "positive": "The structure and properties of vacancies in Si nano-crystals calculated\n  by real-space pseudopotential methods: The structure and properties of vacancies in a 2 nm Si nano-crystal are\nstudied using a real space density functional theory/pseudopotential method. It\nis observed that a vacancy's electronic properties and energy of formation are\ndirectly related to the local symmetry of the vacancy site. The formation\nenergy for vacancies and Frenkel pair are calculated. It is found that both\ndefects have lower energy in smaller crystals. In a 2 nm nano-crystal the\nenergy to form a Frenkel pair is 1.7 eV and the energy to form a vacancy is no\nlarger than 2.3 eV. The energy barrier for vacancy diffusion is examined via a\nnudged elastic band algorithm."
    },
    {
        "anchor": "Study and characterization of SrTiO3 surface: The two-dimensional electron gas (2DEG) at oxides interfaces and surfaces has\nattracted large attention in physics and research due to its unique electronic\nproperties and possible application in optoelectronics and nanoelectronics. The\norigin of 2DEGes at oxide interfaces has been attributed to the well known\n\"polar catastrophe\" mechanism. On the other hand, recently a 2DEG was also\nfound on a clean SrTiO3(001) surface where it is formed due to oxygen\nvacancies. However, these 2DEG systems have been until now found mostly on\natomically perfect crystalline samples usually grown by pulsed laser deposition\nor molecular beam epitaxy i.e. samples which are difficult to be prepared and\nrequire specific experimental conditions. Here, we report on the fabrication of\nSrTiO3 thin films deposited by magnetron sputtering which is suitable for\nmass-production of samples adapted for nanoelectronic applications. The\ncharacterization of their structural and electronic properties was done and\ncompared to those of SrTiO3 single crystals. XRD patterns and SEM micrography\nshow that the deposited films are amorphous and their structure changes to\npolycrystalline by heating them at 900 {\\deg}C. Photoemission spectroscopy (XPS\nand UPS) was used to study the electronic properties of the films and the\ncrystal. In both, we observe the 2DEG system at Fermi level and the formation\nof Ti3+ states after heating the surface at 900 {\\deg}C.",
        "positive": "103-Compound Band Structure Benchmark of Post-SCF Spin-Orbit Coupling\n  Treatments in Density-Functional Theory: We quantify the accuracy of different non-self-consistent and self-consistent\nspin-orbit coupling (SOC) treatments in Kohn-Sham and hybrid density-functional\ntheory by providing a band structure benchmark set for the valence and\nlow-lying conduction energy bands of 103 inorganic compounds, covering chemical\nelements up to Po. Reference energy band structures for the PBE density\nfunctional are obtained using the full-potential (linearized) augmented plane\nwave code Wien2k, employing its self-consistent treatment of SOC including\nDirac-like p$^{1/2}$ orbitals in the basis set. We use this benchmark set to\nbenchmark a computationally simpler, non-self-consistent all-electron treatment\nof SOC based on scalar-relativistic orbitals and numeric atom-centered orbital\nbasis functions. For elements up to Z$\\approx$50, both treatments agree\nvirtually exactly. For the heaviest elements considered (Tl, Pb, Bi, Po), the\nband structure changes due to SOC are captured with a relative deviation of 11%\nor less. For different density functionals (PBE vs. the hybrid HSE06), we show\nthat the effect of spin-orbit coupling is usually similar but can be dissimilar\nif the qualitative features of the predicted underlying scalar-relativistic\nband structures do not agree. All band structures considered in this work are\navailable online via the NOMAD Repository to aid in future benchmark studies\nand methods development."
    },
    {
        "anchor": "Magnetic semimetals and quantized anomalous Hall effect in EuB6: Exploration of the novel relationship between magnetic order and topological\nsemimetals has received enormous interest in a wide range of both fundamental\nand applied research. Here we predict that soft ferromagnetic (FM) material\nEuB6 can achieve multiple topological semimetal phases by simply tuning the\ndirection of the magnetic moment. Explicitly, EuB6 is a topological nodal-line\nsemimetal when the moment is aligned along the [001] direction, and it evolves\ninto a Weyl semimetal with three pairs of Weyl nodes by rotating the moment to\nthe [111] direction. Interestingly, we identify a novel semimetal phase\nfeaturing the coexistence of a nodal line and Weyl nodes with the moment in the\n[110] direction. Topological surface states and anomalous Hall conductivity,\nwhich is sensitive to the magnetic order, have been computed and are expected\nto be experimentally observable. Large-Chern-number quantum anomalous Hall\neffect can be realized in its [111]-oriented quantum-well structure.",
        "positive": "Influence of P2O5 and SiO2 addition on the phase, microstructure, and\n  electrical properties of KNbO3: In this contribution, the effect of P2O5 and SiO2 addition on the phase,\nmicrostructure, and electrical properties of KNbO3 was studied. Sample powders\nwith the general formula (1-x)KNbO3.xP2O5 (x = 0.03, 0.05) and (1-x)KNbO3.xSiO2\n(x = 0.1) were prepared via mixed-oxide route. The thermal behavior of the\nmixed-milled powder was investigated by TG/DTA which revealed an overall weight\nloss of 33.4 wt % in the temperature range of 30 < T < 1200 C and\ncrystallization exotherm occurring at about 795 C. The present results\nindicated that P2O5 acted as a sintering aid and lowered the sintering\ntemperature by about 30 C and promoted densification of KNbO3. Sample\ncompositions at various stages of processing were characterized using X-ray\ndiffraction. Samples sintered at T < 1020 C revealed mainly KNbO3 together with\na couple of low-intensity K3NbO4 peaks as a secondary phase. The SEM images of\n(1-x)KNbO3.xSiO2 (x = 0.1) samples showed a slight increase in the average\ngrain size from 3.76 um to 3.86 um with an increase in sintering temperature\nfrom 1000 C to 1020 C. Strong variations in dielectric constant and loss\ntangent were observed due to P2O5 and SiO2 addition as well as frequency of the\napplied AC signals."
    },
    {
        "anchor": "How Spin Relaxes and Dephases in Bulk Halide Perovskites: Spintronics in halide perovskites has drawn significant attention in recent\nyears, due to highly tunable spin-orbit fields and intriguing interplay with\nlattice symmetry. Spin lifetime -- a key parameter that determines the\napplicability of materials for spintronics and spin-based quantum information\napplications -- has been extensively measured in halide perovskites, but not\nyet assessed from first-principles calculations. Here, we leverage our\nrecently-developed \\emph{ab initio} density-matrix dynamics framework to\ncompute the spin relaxation time ($T_{1}$) and ensemble spin dephasing time\n($T_{2}^{*}$) in a prototype halide perovskite, namely CsPbBr$_{3}$ with\nself-consistent spin-orbit coupling (SOC) and quantum descriptions of the\nelectron scattering processes. We also implement the Land\\'e $g$-factor for\nsolids from first principles and take it into account in our dynamics, which is\nrequired to accurately capture spin dephasing at external magnetic fields. We\nthereby predict intrinsic spin lifetimes as an upper bound for experiments,\nidentify the dominant spin relaxation pathways, and evaluate the dependence on\ntemperature, external fields, carrier density,and impurities. Importantly, we\nfind that the Fr{\\\"o}hlich interaction that dominates carrier relaxation\ncontributes negligibly to spin relaxation, consistent with the spin-conserving\nnature of this interaction. We investigated the effect of spin-orbit field with\ninversion asymmetry on spin lifetime, and we demonstrated from our calculation,\npersistent spin helix can enhance spin lifetime when the spin-split is large,\nbut it can not be realized by Rashba SOC. Our theoretical approach may lead to\nnew strategies to optimize spin and carrier transport properties in spintronics\nand quantum information applications.",
        "positive": "Antiferromagnetic spin Seebeck Effect: We report on the observation of the spin Seebeck effect in antiferromagnetic\nMnF$_2$. A device scale on-chip heater is deposited on a bilayer of Pt (4\nnm)/MnF$_2$ (110) (30 nm) grown by molecular beam epitaxy on a MgF$_2$ (110)\nsubstrate. Using Pt as a spin detector layer it is possible to measure\nthermally generated spin current from MnF$_2$ through the inverse spin Hall\neffect. The low temperature (2 - 80 K) and high magnetic field (up to 140 kOe)\nregime is explored. A clear spin flop transition corresponding to the sudden\nrotation of antiferromagnetic spins out of the easy axis is observed in the\nspin Seebeck signal when large magnetic fields (>9 T) are applied parallel the\neasy axis of the MnF$_2$ thin film. When magnetic field is applied\nperpendicular to the easy axis, the spin flop transition is absent, as\nexpected."
    },
    {
        "anchor": "Unexpectedly Spontaneous Water Dissociation on Graphene Oxide Supported\n  by Copper Substrate: Water dissociation is of fundamental importance in scientific fields and has\ndrawn considerable interest in diverse technological applications. However, the\nhigh activation barrier of breaking the O-H bond within the water molecule has\nbeen identified as the bottleneck, even for the water adsorbed on the graphene\noxide (GO). Herein, using the density functional theory calculations, we\ndemonstrate that the water molecule can be spontaneously dissociated on GO\nsupported by the (111) surface of the copper substrate (Copper-GO). This\nprocess involves a proton transferring from water to the interfacial oxygen\ngroup, and a hydroxide covalently bonding to GO. Compared to that on GO, the\nwater dissociation barrier on Copper-GO is significantly decreased to be less\nthan or comparable to thermal fluctuations. This is ascribed to the\norbital-hybridizing interaction between copper substrate and GO, which enhances\nthe reaction activity of interfacial oxygen groups along the basal plane of GO\nfor water dissociation. Our work provides a novel strategy to access water\ndissociation via the substrate-enhanced reaction activity of interfacial oxygen\ngroups on GO and indicates that the substrate can serve as an essential key to\ntuning the catalytic performance of various two-dimensional material devices.",
        "positive": "Burst statistics as a criterion for imminent failure: The distribution of the magnitudes of damage avalanches during a failure\nprocess typically follows a power law. When these avalanches are recorded close\nto the point at which the system fails catastrophically, we find that the power\nlaw has an exponent which differs from the one characterizing the size\ndistribution of all avalanches. We demonstrate this analytically for bundles of\nmany fibers with statistically distributed breakdown thresholds for the\nindividual fibers. In this case the magnitude distribution $D(\\Delta)$ for the\navalanche size $\\Delta$ follows a power law $\\Delta^{-\\xi}$ with $\\xi=3/2$ near\ncomplete failure, and $\\xi=5/2$ elsewhere. We also study a network of electric\nfuses, and find numerically an exponent 2.0 near breakdown, and 3.0 elsewhere.\nWe propose that this crossover in the size distribution may be used as a signal\nfor imminent system failure."
    },
    {
        "anchor": "Non-necessity of band inversion process in 2D topological insulators for\n  bulk gapless states and topological phase transitions: In commonly employed models for 2D topological insulators, bulk gapless\nstates are well known to form at the band inversion points where the degeneracy\nof the states is protected by symmetries. It is thus sometimes quite tempting\nto consider this feature, the occurrence of gapless states, a result of the\nband inversion process under protection of the symmetries. Similarly, the band\ninversion process might even be perceived as necessary to induce 2D topological\nphase transitions. To clarify these misleading perspectives, we propose a\nsimple model with a flexible Chern number to demonstrate that the bulk gapless\nstates emerge at the phase boundary of topological phase transitions, despite\nthe absence of band inversion process. Furthermore, the bulk gapless states do\nnot need to occur at the special $k$-points protected by symmetries. Given the\nsignificance of these fundamental \\textit{conceptual} issues and their\nwide-spread influence, our clarification should generate strong general\ninterests and significant impacts. Furthermore, the simplicity and flexibility\nof our general model with an arbitrary Chern number should prove useful in a\nwide range of future studies of topological states of matter.",
        "positive": "First principles studies of the size and shape effects on reactivity of\n  the Se modified Ru nanoparticles: We present here the results of our density-functional-theory-based\ncalculations of the electronic and geometric structures and energetics of Se\nand O adsorption on Ru 93- and 105-atom nanoparticles. These studies have been\ninspired by the fact that Se/Ru nanoparticles are considered promising\nelectrocatalysts for the oxygen reduction reaction (ORR) on the direct methanol\nfuel cell cathodes and the oxygen binding energy is a descriptor for the\ncatalyst activity towards this reaction. We find the character of chemical\nbonding of Se on a flat nanoparticle facet to be ionic, similar to that\nobtained earlier for the Se/Ru(0001) surface, while in the case of a low\ncoordinated Ru configuration there is an indication of some covalent\ncontribution to the bonding leading to an increase in Se binding energy. Se and\nO co-adsorbed on the flat facet, both accept electronic charge from Ru, whereas\nthe adsorption on low-coordinated sites causes more complicated valence charge\nredistribution. The Se modification of the Ru particles leads to weakening of\nthe oxygen bonding to the particle. However, overall, O binding energies are\nfound to be higher for the particles than for Se/Ru(0001). High reactivity of\nthe Se/Ru nanoparticles found in this work is not favorable for ORR. We thus\nexpect that larger particles with well-developed flat facets are more efficient\nORR catalysts than small nanoparticles with a large fraction of\nunder-coordinated adsorption sites."
    },
    {
        "anchor": "Two-dimensional higher-order topology in monolayer graphdiyne: Based on first-principles calculations and tight-binding model analysis, we\npropose monolayer graphdiyne as a candidate material for a two-dimensional\nhigher-order topological insulator protected by inversion symmetry. Despite the\nabsence of chiral symmetry, the higher-order topology of monolayer graphdiyne\nis manifested in the filling anomaly and charge accumulation at two corners.\nAlthough its low energy band structure can be properly described by the\ntight-binding Hamiltonian constructed by using only the $p_z$ orbital of each\natom, the corresponding bulk band topology is trivial. The nontrivial bulk\ntopology can be correctly captured only when the contribution from the core\nlevels derived from $p_{x,y}$ and $s$ orbitals are included, which is further\nconfirmed by the Wilson loop calculations. We also show that the higher-order\nband topology of a monolayer graphdyine gives rise to the nontrivial band\ntopology of the corresponding three-dimensional material, ABC-stacked\ngraphdiyne, which hosts monopole nodal lines and hinge states.",
        "positive": "Molecular dynamics of a short range ordered smectic phase nanoconfined\n  into porous silicon: 4-n-octyl-4-cyanobiphenyl (8CB) has been recently shown to display an unusual\nsequence of phases when confined into porous silicon (PSi). The gradual\nincrease of oriented short-range smectic (SRS) correlations in place of a phase\ntransition has been interpreted as a consequence of the anisotropic quenched\ndisorder induced by confinement in PSi. Combining two quasielastic neutron\nscattering experiments with complementary energy resolutions, we present the\nfirst investigation of the individual molecular dynamics of this system. A\nlarge reduction of the molecular dynamics is observed in the confined liquid\nphase, as a direct consequence of the dynamical boundary conditions imposed by\nthe confinement. Temperature fixed window scans (FWS) reveal a continuous\n'glass-like' reduction of the molecular dynamics of the confined liquid and SRS\nphases on cooling down to 250 K, where a solid-like behavior is finally reached\nby a two steps crystallization process."
    },
    {
        "anchor": "Metal-Organic Frameworks in Germany: from Synthesis to Function: Metal-organic frameworks (MOFs) are constructed from a combination of\ninorganic and organic units to produce materials which display high porosity,\namong other unique and exciting properties. MOFs have shown promise in many\nwide-ranging applications, such as catalysis and gas separations. In this\nreview, we highlight MOF research conducted by Germany-based research groups.\nSpecifically, we feature approaches for the synthesis of new MOFs,\nhigh-throughput MOF production, advanced characterization methods and examples\nof advanced functions and properties.",
        "positive": "Total electronic energy by tight binding approximation and experimental\n  toughness of three different hybrid polymers: We computed by a modified tight binding approximation, the total electronic\nenergy of three different hybrid polymers: $H-SiO_2$, $CH_3-SiO_2$ and\n$C_6H_5-SiO_2$. We made the hypothesis that the structures of these polymers\nare amorphous. Computational results regarding the total electronic energy and\nexperimental data \\cite{ferchichi} on the toughness of these three hybrid\npolymers were compared. A good qualitative agreement was found between\ncomputations and experiments."
    },
    {
        "anchor": "Angle-adjustable density field formulation for modeling crystalline\n  microstructures: A continuum density-field formulation with particle-scale resolution is\nconstructed to simultaneously incorporate the orientation dependence of\ninterparticle interactions and the rotational invariance of the system, a\nfundamental but challenging issue in modeling structure and dynamics of a broad\nrange of material systems across variable scales. This generalized phase field\ncrystal type approach is based upon the complete expansion of particle direct\ncorrelation functions and the concept of isotropic tensors. Through\napplications to the modeling of various two- and three-dimensional crystalline\nstructures, our study demonstrates the capability of bond angle control in this\ncontinuum field theory and its effects on the emergence of ordered phases, and\nprovides a systematic way of tunable angle analysis for crystalline\nmicrostructures.",
        "positive": "Disorder-induced ordering in gallium oxide polymorphs: Polymorphs are common in nature and can be stabilized by applying external\npressure in materials. The pressure/strain can also be induced by the gradually\naccumulated radiation disorder. However, in semiconductors, the radiation\ndisorder accumulation typically results in the amorphization instead of\nengaging polymorphism. By studying these phenomena in gallium oxide we found\nthat the amorphization may be prominently suppressed by the monoclinic to\northorhombic phase transition. Utilizing this discovery, a highly oriented\nsingle-phase orthorhombic film on the top of the monoclinic gallium oxide\nsubstrate was fabricated. Exploring this system, a novel mode of a lateral\npolymorphic regrowth, not previously observed in solids, was detected. In\ncombination, these data envisage a new direction of research on polymorphs in\nGa2O3 and, potentially, for similar polymorphic families in other materials."
    },
    {
        "anchor": "Spin-polarized quasi 1D state with finite bandgap on the Bi/InSb(001)\n  surface: One-dimensional (1D) electronic states were discovered on 1D surface atomic\nstructure of Bi fabricated on semiconductor InSb(001) substrates by\nangle-resolved photoelectron spectroscopy (ARPES). The 1D state showed steep,\nDirac-cone-like dispersion along the 1D atomic structure with a finite direct\nbandgap opening as large as 150 meV. Moreover, spin-resolved ARPES revealed the\nspin polarization of the 1D unoccupied states as well as that of the occupied\nstates, the orientation of which inverted depending on the wave vector\ndirection parallel to the 1D array on the surface. These results reveal that a\nspin-polarized quasi-1D carrier was realized on the surface of 1D Bi with\nhighly efficient backscattering suppression, showing promise for use in future\nspintronic and energy-saving devices.",
        "positive": "Foucault imaging and small-angle electron diffraction in controlled\n  external magnetic fields: We report a method for acquiring Foucault images and small-angle electron\ndiffraction patterns in external magnetic fields using a conventional\ntransmission electron microscope without any modification. In the electron\noptical system that we have constructed, external magnetic fields parallel to\nthe optical axis can be controlled using the objective lens pole piece under\nweak excitation conditions in the Foucault mode and the diffraction mode. We\nobserve two ferromagnetic perovskite-type manganese oxides,\nLa$_{0.7}$Sr$_{0.3}$MnO$_{3}$ and Nd$_{0.5}$Sr$_{0.5}$MnO$_{3}$, in order to\nvisualize magnetic domains and their magnetic responses to external magnetic\nfields. In rhombohedral-structured La$_{0.7}$Sr$_{0.3}$MnO$_{3}$, pinning of\nmagnetic domain walls at crystallographic twin boundaries was found to have a\nstrong influence on the generation of new magnetic domains in external applied\nmagnetic fields."
    },
    {
        "anchor": "Studies of CoFeB crystalline structure grown on PbSnTe topological\n  insulator substrate: Co40Fe40B20 layers were grown on the Pb0.71Sn0.29Te topological insulator\nsubstrates by laser molecular beam epitaxy (LMBE) method, and the growth\nconditions were studied. The possibility of growing epitaxial layers of a\nferromagnet on the surface of a topological insulator was demonstrated for the\nfirst time. The Co40Fe40B20 layers obtained have a bcc crystal structure with a\ncrystalline (111) plane parallel to the (111) PbSnTe plane. The use of\nthree-dimensional mapping in the reciprocal space of reflection high electron\ndiffraction (RHEED) patterns made it possible to determine the epitaxial\nrelationship of main crystallographic axes between the film and the substrate\nof topological insulator. Quenching of some reflections in diffraction pattern\nallows confirmation of the substrate stoichiometry.",
        "positive": "Orthorhombic phase of La$_{0.5}$Bi$_{0.5}$NiO$_{3}$ studied by first\n  principles: The aim of presented first principles study of La$_{0.5}$Bi$_{0.5}$NiO$_{3}$\nis to investigate electronic structure of orthorhombic phase Pbnm. The\ncalculations show that metallicity and magnetism of the system are strongly\nrelated with hybridization between Ni 3d and O 2p. To improve the quality of\nthe electronic structure description of the system, especially the treatment of\ncorrelation for the Ni 3d, we employ GGA, LDA, and GGA+U, LDA+U. The LSDA\nresults give good agreement with experiment. Thus, the screening effects\noriginating from the hybridized 3d and O 2p electrons are sufficiently strong\nthat they reduce the electronic correlations in the\nLa$_{0.5}$Bi$_{0.5}$NiO$_{3}$, making it a weakly correlated metal."
    },
    {
        "anchor": "Multiscale modeling of kinetic sluggishness in equiatomic NiCoCr and\n  NiCoCrFeMn single-phase solid solutions: Complex, concentrated, multi-component alloys have been shown to display\noutstanding thermo-mechanical properties, that have been typically attributed\nto sluggish diffusion, entropic, and lattice distortion effects. Here, we\ninvestigate two metal alloys with such exemplary properties, the equiatomic,\nsingle-phase, face-centered-cubic (FCC) alloys NiCoCr and NiCoCrFeMn, and we\ncompare their microstructural kinetics to the behaviors in a pure-Ni FCC metal.\nWe perform long-time, kinetic Monte Carlo (kMC) simulations, and we analyze in\ndetail the kinetics of atomic vacancies. We find that vacancies in both\nconcentrated alloys exhibit subdiffusive thermally driven dynamics, in direct\ncontrast to the diffusive dynamics of pure Ni. Subdiffusive dynamics shall be\nattributed to dynamical sluggishness, that is modeled by a fractional Brownian\nrandom walk. Furthermore, we analyze the statistics of waiting times, and we\ninterpret long power-law-distributed rest periods as a direct consequence of\nbarriers' energy-scales and lattice distortions.",
        "positive": "Electronic properties of ternary quasicrystals in one dimension: The one-electron properties of a certain class of one-dimensional ternary\nquasicrystals are investigated. In particular, we show in detail the presence\nof a special kind of critical states called marginal critical states in these\nQCs. By the use of a real-space renormalization-group method, it is shown that\nthe scaling properties of marginal critical states are characterized by\nstretched exponentials. These states are virtually localized, so that their\npresence may make a QC less conductive."
    },
    {
        "anchor": "Microstructure Representation and Reconstruction of Heterogeneous\n  Materials via Deep Belief Network for Computational Material Design: Integrated Computational Materials Engineering (ICME) aims to accelerate\noptimal design of complex material systems by integrating material science and\ndesign automation. For tractable ICME, it is required that (1) a structural\nfeature space be identified to allow reconstruction of new designs, and (2) the\nreconstruction process be property-preserving. The majority of existing\nstructural presentation schemes rely on the designer's understanding of\nspecific material systems to identify geometric and statistical features, which\ncould be biased and insufficient for reconstructing physically meaningful\nmicrostructures of complex material systems. In this paper, we develop a\nfeature learning mechanism based on convolutional deep belief network to\nautomate a two-way conversion between microstructures and their\nlower-dimensional feature representations, and to achieves a 1000-fold\ndimension reduction from the microstructure space. The proposed model is\napplied to a wide spectrum of heterogeneous material systems with distinct\nmicrostructural features including Ti-6Al-4V alloy, Pb63-Sn37 alloy,\nFontainebleau sandstone, and Spherical colloids, to produce material\nreconstructions that are close to the original samples with respect to 2-point\ncorrelation functions and mean critical fracture strength. This capability is\nnot achieved by existing synthesis methods that rely on the Markovian\nassumption of material microstructures.",
        "positive": "Molecular beam epitaxy growth of the highly conductive oxide SrMoO$_3$: SrMoO$_3$ is a promising material for its excellent electrical conductivity,\nbut growing high-quality thin films remains a challenge. Here we synthesized\nepitaxial films of SrMoO$_3$ using the molecular beam epitaxy (MBE) technique\nunder a low oxygen-flow rate. Introduction of SrTiO$_3$ buffer layers of 4--8\nunit cells between the film and the (001)-oriented SrTiO$_3$ or KTaO$_3$\nsubstrate was crucial to remove impurities and/or roughness of the film\nsurface. The obtained film shows improved electrical conductivities as compared\nwith films obtained by other techniques. The high quality of the SrMoO$_3$ film\nis also verified by angle-resolved photoemission spectroscopy (ARPES)\nmeasurements showing clear Fermi surfaces."
    },
    {
        "anchor": "Mapping the metastability of Lennard-Jones clusters by the maximum\n  vibrational frequency: We study the structure-stability relationship of the Lennard-Jones (LJ)\nclusters from a point of view of vibrations. By assuming the size up to\n$N=1610$, we demonstrate that the $N$-dependence of the maximum vibrational\nfrequency reflects the geometry of the core (the interior of cluster) that will\ndetermine the overall geometry of the cluster. This allows us to identify the\nformation of non-icosahedral structures for $N\\le 150$, the vacancy formation\nat the core for $N\\ge 752$, and the transition from icosahedral to decahedral\nstructures at $N = 1034$. We apply the maximum frequency analysis to classify\nmetastable clusters for $19\\le N \\le 39$, where transformation pathways between\ndifferent structures are visualized, and the energy barrier height is estimated\nsimultaneously.",
        "positive": "Wide Range Thin-FIlm Ceramic Metal-Alloy Thermometers with Low\n  Magnetoresistance: Many thermal measurements in high magnetic fields require thermometers that\nare sensitive over a wide temperature range, are low mass, have a rapid thermal\nresponse, and have a minimal, easily correctable magnetoresistance. Here we\nreport the development of a new granular-metal oxide ceramic composite (cermet)\nfor this purpose formed by co-sputtering of the metallic alloy nichrome\nNi$_{0.8}$Cr$_{0.2}$ and the insulator silcon dioxide SiO$_2$. The resulting\nthin films are sensitive enough to be used from room temperature down to below\n100 mK in magnetic fields up to at least 35 tesla."
    },
    {
        "anchor": "M$^2$Hub: Unlocking the Potential of Machine Learning for Materials\n  Discovery: We introduce M$^2$Hub, a toolkit for advancing machine learning in materials\ndiscovery. Machine learning has achieved remarkable progress in modeling\nmolecular structures, especially biomolecules for drug discovery. However, the\ndevelopment of machine learning approaches for modeling materials structures\nlag behind, which is partly due to the lack of an integrated platform that\nenables access to diverse tasks for materials discovery. To bridge this gap,\nM$^2$Hub will enable easy access to materials discovery tasks, datasets,\nmachine learning methods, evaluations, and benchmark results that cover the\nentire workflow. Specifically, the first release of M$^2$Hub focuses on three\nkey stages in materials discovery: virtual screening, inverse design, and\nmolecular simulation, including 9 datasets that covers 6 types of materials\nwith 56 tasks across 8 types of material properties. We further provide 2\nsynthetic datasets for the purpose of generative tasks on materials. In\naddition to random data splits, we also provide 3 additional data partitions to\nreflect the real-world materials discovery scenarios. State-of-the-art machine\nlearning methods (including those are suitable for materials structures but\nnever compared in the literature) are benchmarked on representative tasks. Our\ncodes and library are publicly available at https://github.com/yuanqidu/M2Hub.",
        "positive": "Electrochemical Degradation of Per- and Polyfluoroalkyl Substances\n  (PFAS) using Low-cost Graphene Sponge Electrodes: Boron-doped, graphene sponge anode was synthesized and applied for the\nelectrochemical oxidation of C4-C8 per and polyfluoroalkyl substances (PFASs).\nRemoval efficiencies, obtained in low conductivity electrolyte (1 mS cm-1) and\none-pass flow-through mode, were in the range 16.7-67% at 230 A m-2 of anodic\ncurrent density, and with the energy consumption of 10.1+-0.7 kWh m-3. Their\nremoval was attributed to electrosorption (7.4-35%), and electrooxidation\n(9.3-32 %). Defluorination efficiencies of C4-C8 perfluoroalkyl sulfonates and\nacids were 8-24% due to a fraction of PFAS being electrosorbed only at the\nanode surface. Yet, the recovery of fluoride was 74-87% relative to the\nelectrooxidized fraction, suggesting that once the degradation of the PFAS is\ninitiated, the C-F bond cleavage is very efficient. The nearly stoichiometric\nsulfate recoveries obtained for perfluoroalkyl sulfonates (91-98%) relative to\nthe electrooxidized fraction demonstrated an efficient cleavage of the\nsulfonate head-group. Adsorbable organic fluoride (AOF) analysis showed that\nthe remaining partially defluorinated byproducts are electrosorbed at the\ngraphene sponge anode during current application and are released into the\nsolution after the current is switched off. This proof-of-concept study\ndemonstrated that the developed graphene sponge anode is capable of C-F bond\ncleavage and defluorination of PFAS. Given that the graphene sponge anode is\nelectrochemically inert towards chloride and does not form any chlorate and\nperchlorate even in brackish solutions, the developed material may unlock the\nelectrochemical degradation of PFAS complex wastewaters and brines."
    },
    {
        "anchor": "Larger photovoltaic effect and hysteretic photocarrier dynamics in\n  Pb[(Mg1/3Nb2/3)0.70Ti0.30]O3 crystal: Following the recent discovery of a bulk photovoltaic effect in the\nPb[(Mg1/3Nb2/3)0.68Ti0.32]O3 crystal, we report here more than one order of\nmagnitude improvement of photovoltaicity as well as its poling dependence in\nthe related composition of lead magnesium niobate-lead titanate noted\nPb[(Mg1/3Nb2/3)0.7Ti0.30]O3. Photocurrent measurements versus light intensity\nreveal a fascinating hysteretic charge carriers dynamics clearly demonstrating\ncharge generation, trapping and release processes.",
        "positive": "IrCrMnZ (Z=Al, Ga, Si, Ge) Heusler alloys as electrode materials for\n  MgO-based magnetic tunneling junctions: A first-principles study: We study IrCrMnZ (Z=Al, Ga, Si, Ge) systems using first-principles\ncalculations from the perspective of their application as the electrode\nmaterials of MgO-based MTJs. These materials have highly spin-polarized\nconduction electrons with partially occupied $\\Delta_1$ band, which is\nimportant for coherent tunneling in parallel magnetization configuration. The\nCurie temperatures of IrCrMnAl and IrCrMnGa are very high (above 1300 K) as\npredicted from mean-field-approximation. The stability of ordered phase against\nvarious antisite disorders has been investigated. We discuss here the effect of\n\"spin-orbit-coupling\" on the electronic structure around Fermi level. Further,\nwe investigate the electronic structure of IrCrMnZ/MgO heterojunction along\n(001) direction. IrCrMnAl/MgO and IrCrMnGa/MgO maintain half-metallicity even\nat the MgO interface, with no interfacial states at/around Fermi level in the\nminority-spin channel. Large majority-spin conductance of IrCrMnAl/MgO/IrCrMnAl\nand IrCrMnGa/MgO/IrCrMnGa is reported from the calculation of ballistic\nspin-transport property for parallel magnetization configuration. We propose\nIrCrMnAl/MgO/IrCrMnAl and IrCrMnGa/MgO/IrCrMnGa as promising MTJs with a weaker\ntemperature dependence of tunneling magnetoresistance ratio, owing to their\nvery high Curie temperatures."
    },
    {
        "anchor": "Thermal Conductivity of BAs under Pressure: The thermal conductivity of boron arsenide (BAs) is believed to be influenced\nby phonon scattering selection rules due to its special phonon dispersion.\nCompression of BAs leads to significant changes in phonon dispersion, which\nallows for a test of first principles theories for how phonon dispersion\naffects three- and four-phonon scattering rates. This study reports the thermal\nconductivity of BAs from 0 to 30 GPa. Thermal conductivity vs. pressure of BAs\nis measured by time-domain thermoreflectance with a diamond anvil cell. In\nstark contrast to what is typical for nonmetallic crystals, BAs is observed to\nhave a pressure independent thermal conductivity below 30 GPa. The thermal\nconductivity of nonmetallic crystals typically increases upon compression. The\nunusual pressure independence of thermal conductivity of BAs shows the\nimportant relationship between phonon dispersion properties and three- and\nfour-phonon scattering rates.",
        "positive": "Non-uniformity of a planar polarizer as a reason of spin-transfer\n  induced vortex oscillations at zero field: We discuss a possible mechanism of the spin-transfer induced oscillations of\na vortex in the free layer of spin-valve nanostructures, in which the polarizer\nlayer has a planar magnetization. We demonstrate that if such planar polarizer\nis essentially non-uniform, steady gyrotropic vortex motion with large\namplitude can be excited. The best excitation efficiency is obtained for a\ncircular magnetization distribution in the polarizer. In this configuration,\nthe conditions for the onset of the oscillations depend on the vortex chirality\nbut not on the direction of its core."
    },
    {
        "anchor": "Prediction of crystallized phases of amorphous Ta$_2$O$_5$-based mixed\n  oxide thin films using density functional theory calculations: The genomics approach to materials, heralded by increasingly accurate density\nfunctional theory (DFT) calculations conducted on thousands of crystalline\ncompounds, has led to accelerated material discovery and property predictions.\nHowever, so far amorphous materials have been largely excluded from this as\nthese systems are notoriously difficult to simulate. Here we study amorphous\nTa$_2$O$_5$ thin films mixed with Al$_2$O$_3$, SiO$_2$, Sc$_2$O$_3$, TiO$_2$,\nZnO, ZrO$_2$, Nb$_2$O$_5$ and HfO$_2$ to identify their crystalline structure\nupon post-deposition annealing in air both experimentally and with simulations.\nUsing the Materials Project open database, phase diagrams based on DFT\ncalculations are constructed for the mixed oxide systems and the annealing\nprocess is evaluated via grand potential diagrams with varying oxygen chemical\npotential. Despite employing calculations based on crystalline bulk materials,\nthe predictions agree well with the experimentally observed crystallized phases\nof the amorphous films. Only in two cases the database leads to incorrect\npredictions: in TiO$_2$-doped Ta$_2$O$_5$ because it does not contain a ternary\ncompound found experimentally, and in Sc$_2$O$_3$-doped Ta$_2$O$_5$ because DFT\noverestimates the formation enthalpy difference between Sc$_2$O$_3$ and\nTa$_2$O$_5$ and thus does not reproduce observed oxygen competition effects. In\nthe absence of ternary phases, the dopant acts as an amorphizer agent\nincreasing the thermal stability of Ta$_2$O$_5$. These results show that DFT\ncalculations can be applied for the prediction of crystallized structures of\nannealed amorphous materials. This could pave the way for accelerated\n\\textit{in silico} material discovery and property predictions using the\npowerful genomic approach for amorphous oxide coatings employed in a wide range\nof applications such as optical coatings, energy storage and electronic\ndevices.",
        "positive": "Charge Transport Properties of a Metal-free Phthalocyanine Discotic\n  Liquid Crystal: Discotic liquid crystals can self-align to form one-dimensional\nsemiconducting wires, many tens of microns long. In this letter, we describe\nthe preparation of semiconducting films where the stacking direction of the\ndisc-like molecules is perpendicular to the substrate surface. We present\nmeasurements of the charge carrier mobility, applying temperature-dependent\ntime-of-flight transient photoconductivity, space-charge limited current\nmeasurements, and field-effect mobility measurements. We provide experimental\nverification of the highly anisotropic nature of semiconducting films of\ndiscotic liquid crystals, with charge carrier mobilities of up to\n2.8x10$^{-3}$cm$^2$/Vs. These properties make discotics an interesting choice\nfor applications such as organic photovoltaics."
    },
    {
        "anchor": "Multiscale insight into the Cd1-xZnxTe vibrational-mechanical properties\n  -- High-pressure experiments and ab initio calculations: The Cd1-xZnxTe semiconductor alloy is a regular system regarding its\nmacroscopic mechanic properties in that its experimental bulk modulus exhibits\na linear x-dependence, in line with ab initio predictions. Complexity arises at\nthe bond scale, referring to the intricate Cd1-xZnxTe percolation-type Raman\npattern [T. Alhaddad et al., Journal of Applied Physics 133, 065701 (2023)].\nThis offers an appealing benchmark to test various phonon coupling processes at\ndiverse length scales in a compact multi-oscillator assembly, presently tuned\nby pressure. At x around 0, an inter-bond long-range/macro electric coupling\nbetween the matrix and impurity polar phonons is detuned under pressure.\nInversely, at x around 1, an intra-bond short-range/nano mechanic coupling is\nenforced between the two Zn Te apolar sub-phonons stemming from same and alien\npercolation-type environments. The pressure-induced macro/nano polar/apolar\ncoupling/decoupling processes are compared within a model of two coupled\nelectric/mechanic harmonic oscillators in terms of a compromise between\nproximity to resonance and strength of coupling, impacting the degree of mode\nmixing, with ab initio (apolar case) and analytical (polar case) Raman\ncalculations in support. Notably, the free mechanic coupling at x around 1\nopposes the achievement of a phonon exceptional point, manifesting the\ninhibition of mechanic coupling, earlier evidenced with similar bonds for x\nsmaller than 0.5. Hence, the pressure dependence of a given bond vibration in a\ndisordered alloy basically differs depending on whether the bond is\nmatrix-like, i.e., self-connected in bulk (free coupling), or dispersed, i.e.,\nself-connected in a chain (inhibited coupling). This features pressure-tunable\npercolation-based on-off phonon switches in complex media.",
        "positive": "Effects of Grain Boundaries and Surfaces on Electronic and Mechanical\n  Properties of Solid Electrolytes: Extended defects, including exposed surfaces and grain boundaries, are\ncritical to the properties of polycrystalline solid electrolytes in\nall-solid-state batteries (ASSBs). These defects can significantly alter the\nmechanical and electronic properties of solid electrolytes, with direct\nmanifestations on the performance of ASSBs. Here, by building a library of 590\nsurfaces and grain boundaries of 11 relevant solid electrolytes $-$including\nhalides, oxides, and sulfides$-$ their electronic, mechanical, and\nthermodynamic characteristics are linked to the functional properties of\npolycrystalline solid electrolytes. It is found that the energy required to\nmechanically ``separate'' grain boundaries can be significantly lower than in\nthe bulk region of materials, which can trigger preferential cracking of solid\nelectrolyte particles in the grain boundary regions. The brittleness of ceramic\nsolid electrolytes, inferred from the predicted low fracture toughnesses at the\ngrain boundaries, contributes to their cracking under local pressure imparted\nby Lithium or Sodium penetration in the grain boundaries. Extended defects of\nsolid electrolytes introduce new electronic ``interfacial'' states within\nbandgaps of solid electrolytes. These interfacial states alter and possibly\nincrease locally the availability of free electrons and holes in solid\nelectrolytes. Factoring effects arising from extended defects appear crucial to\nexplain electrochemical and $-$mechanical observations in ASSBs."
    },
    {
        "anchor": "Machine-Learning Surrogate Model for Accelerating the Search of Stable\n  Ternary Alloys: The prediction of phase diagrams in the search for new phases is a complex\nand computationally intensive task. Density functional theory provides, in many\nsituations, the desired accuracy, but its throughput becomes prohibitively\nlimited as the number of species involved grows, even when used with local and\nsemi-local functionals. Here, we explore the possibility of integrating\nmachine-learning models in the workflow for the construction of ternary convex\nhull diagrams. In particular, we train a set of spectral neighbour-analysis\npotentials (SNAPs) over readily available binary phases and we establish\nwhether this is good enough to predict the energies of novel ternaries. Such a\nstrategy does not require any new calculations specific for the construction of\nthe model, but just avails of data stored in binary-phase-diagram repositories.\nWe find that a so-constructed SNAP is capable of accurate total-energy\nestimates for ternary phases close to the equilibrium geometry but, in general,\nis not able to perform atomic relaxation. This is because during a typical\nrelaxation path a given phase traverses regions in the parameter space poorly\nrepresented by the training set. Different metrics are then investigated to\nassess how an unknown structure is well described by a given SNAP model, and we\nfind that the standard deviation of an ensemble of SNAPs provides a fast and\nnon-specie-specific metric.",
        "positive": "Growth of metamaterial from Isolated nuclei with anisotropic building\n  block: Crystallization has long been the subject of research as one of the basic\nways in which solid materials are constructed. In particular, the nucleation\nstage has not been isolated, thus has been predicted through many calculations\nand achieved theoretical completion through the nucleation rate(J). Si nce most\nof these results were obtained through isotropic building blocks in\nthree-dimensional space, it was difficult to interpret nuclei formed by\nanisotropic building block in 2D or 1D structure. Recently, a lot of studies\nrelated to amyloid fibril have shown nucleation of anisotropic building block.\nHowever, due to the complexity of the amyloid fibrils, there is no unified\nexplanation of the thermodynamic method of classical nucleation theory which is\nthe energy loss from surface and energy gain from volume. We have\nexperimentally demonstrated the isolation of nuclei of the orthorhombic phase\nof HYLION-12 which is a Dirac metamaterial and provide the effect of anisotropy\nof the molecules on nucleation The thermal behavior of nuclei of Dirac\nmetamaterial through DSC has demonstrated that it can be crystallized to a\nDirac metamaterial through the first order phase transition. The growth process\nis verified at low temperature where no phase transition occurs. The\ncalculation of surface and bulk energy of the Dirac metamaterial was conducted.\nIt could explain the isolation of nuclei of the Dirac metamaterial by enlarging\nthe thermodynamic classical nucleation theory."
    },
    {
        "anchor": "MOCVD growth and band offsets of \\k{appa}-phase Ga2O3 on sapphire, GaN,\n  AlN and YSZ substrates: Epitaxial growth of \\k{appa}-phase Ga2O3 thin films are investigated on\nc-plane sapphire, GaN- and AlNon-sapphire, and (100) oriented yttria stabilized\nzirconia (YSZ) substrates via metalorganic chemical vapor deposition (MOCVD).\nThe structural and surface morphological properties are investigated by\ncomprehensive material characterization. Phase pure \\k{appa}-Ga2O3 films are\nsuccessfully grown on GaN-, AlN-on sapphire, and YSZ substrates through a\nsystematical tuning of the growth parameters including the precursor molar flow\nrates, chamber pressure and growth temperature, whereas the growth on\nc-sapphire substrates leads to a mixture of \\b{eta}- and \\k{appa}polymorphs of\nGa2O3 under the investigated growth conditions. The influence of the\ncrystalline structure, surface morphology and roughness of \\k{appa}-Ga2O3 films\ngrown on different substrates are investigated as a function of precursor flow\nrate. High resolution scanning transmission electron microscopy (HR-STEM)\nimaging of \\k{appa}-Ga2O3 films reveals abrupt interfaces between the epitaxial\nfilm and the sapphire, GaN and YSZ substrates. The growth of single crystal\northorhombic \\k{appa}Ga2O3 films is confirmed by analyzing the STEM\nnano-diffraction pattern. The chemical composition, surface stoichiometry, and\nthe bandgap energies of \\k{appa}-Ga2O3 thin films grown on different substrates\nare studied by high resolution x-ray photoelectron spectroscopy (XPS)\nmeasurements. The type-II (staggered) band alignments at three interfaces\nbetween \\k{appa}-Ga2O3 and c-sapphire, AlN, and YSZ substrates are determined\nby XPS, with the exception of \\k{appa}-Ga2O3/GaN interface, which shows type I\n(straddling) band alignment.",
        "positive": "Simple derivation of Young, Wenzel and Cassie-Baxter equations and its\n  interpretations: In this paper we have derived Young's, Wenzel's and Cassie-Baxter's equations\nusing conceptual model rather than showing rigorous derivation to help the\nnew-comers in this field. We then pointed out that if the substrate is\ninitially hydorphilic then one can modify the surface morphology and make the\nsubstrate to become hydrophobic or superhydrophobic. But, if the substrate is\ninitially hydrophobic then one can only make it superhydrophobic but not\nhydrophilic by modifying the surface morphology using the formalisms mentioned\nin this paper"
    },
    {
        "anchor": "Hafnium carbide formation in oxygen deficient hafnium oxide thin films: On highly oxygen deficient thin films of hafnium oxide (hafnia, HfO$_{2-x}$)\ncontaminated with adsorbates of carbon oxides, the formation of hafnium carbide\n(HfC$_x$) at the surface during vacuum annealing at temperatures as low as 600\n{\\deg}C is reported. Using X-ray photoelectron spectroscopy the evolution of\nthe HfC$_x$ surface layer related to a transformation from insulating into\nmetallic state is monitored in situ. In contrast, for fully stoichiometric\nHfO$_2$ thin films prepared and measured under identical conditions, the\nformation of HfC$_x$ was not detectable suggesting that the enhanced adsorption\nof carbon oxides on oxygen deficient films provides a carbon source for the\ncarbide formation. This shows that a high concentration of oxygen vacancies in\ncarbon contaminated hafnia lowers considerably the formation energy of hafnium\ncarbide. Thus, the presence of a sufficient amount of residual carbon in\nresistive random access memory devices might lead to a similar carbide\nformation within the conducting filaments due to Joule heating.",
        "positive": "Huge ac magnetoresistance in La0.7Sr0.3MnO3 in sub- kilo gauss magnetic\n  fields: We report dynamical magnetotransport in a ferromagnetic metallic oxide,\nLa0.7Sr0.3MnO3 using the ac impedance technique. The temperature dependence of\nthe ac resistance(R) and the inductive reactance (X) of the complex impedance\n(Z = R+jX) under different dc bias magnetic fields (Hdc = 0-1 kOe) were studied\nfor different frequencies f = 0.1 to 5 MHz of alternating current. The zero\nfield R, which decreases smoothly around the Curie temperature TC for f = 100\nkHz, transforms into a peak for f = 0.5-5 MHz. The peak decreases in amplitude,\nbroadens and shifts downward in temperature as the bias field increases. A huge\nac magnetoresistance (= 45 % at f = 2 MHz) in a field of Hdc = 1 kOe is found\nand we attribute it to the magnetic field- induced enhancement in the skin\ndepth and concomitant suppression of magnetic fluctuations near TC. Our study\nsuggests that radio frequency magnetotransport provides an alternative strategy\nto enhance the magnetoresistance and probe the spin-charge coupling in\nmanganites."
    },
    {
        "anchor": "Electric field and photo-excited control of the carrier concentration in\n  GdN: We present both electric-field and photo-excited control of the carrier\nconcentration in GdN. There is no evidence in the results of a carrier-mediated\ncontribution to the Gd-Gd exchange interaction that has been suggested to\nexplain a measured Curie temperature that is much higher than obtained within\ntheoretical treatments. Persistent carrier concentrations seen in both the\nfield-effect and photo-induced conductivities point to a distribution of\nlong-lived trap states below the conduction band, very likely centred at\nnitrogen vacancies",
        "positive": "Elastic properties and mechanical tension of graphene: Room temperature simulations of graphene have been performed as a function of\nthe mechanical tension of the layer. Finite-size effects are accurately\nreproduced by an acoustic dispersion law for the out-of-plane vibrations that,\nin the long-wave limit, behaves as $\\rho\\omega^2=\\sigma k^2+\\kappa k^4$. The\nfluctuation tension $\\sigma$ is finite ($\\sim 0.1$ N/m) even when the external\nmechanical tension vanishes. Transverse vibrations imply a duplicity in the\ndefinition of the elastic constants of the layer, as observables related to the\nreal area of the surface may differ from those related to the in-plane\nprojected area. This duplicity explains the variability of experimental data on\nthe Young modulus of graphene based on electron spectroscopy, interferometric\nprofilometery, and indentation experiments."
    },
    {
        "anchor": "Establishing a microscopic model for nonfullerene organic solar cells:\n  Self-accumulation effect of charges: A one-dimensional many-body model is established to mimic the charge\ndistribution and dynamics in nonfullerene organic solar cells. Two essential\nissues are taken into account in the model: The alternating donor and acceptor\nstructure and the local imbalance of the intrinsic electrons and holes. The\nalternating structure is beneficial for the direct generation of charge\ntransfer state which enhances the local imbalance of intrinsic charges. The\nmost remarkable outcome of the model is that, due to the strong Coulomb\nattractive potential energy, the intrinsic charges in the cells are\nself-accumulated in a small spatial region. Outside the self-accumulation\nregion, the charge density vanishes so that the recombination is regarded to be\nlargely suppressed. The photogenerated electrons are subsequently observed to\nspread freely outside the self-accumulation region implying the Coulomb\nattraction does not matter in the ultrafast charge separation dynamics. These\nfindings enable an appealing understanding of the high performance of emerging\nnonfullerene cells, and the designing rules of molecules and devices are then\ncomprehensively discussed.",
        "positive": "Unraveling the unusually high electrical conductivity of the delafossite\n  metal PdCoO$_2$: The prototypical delafossite metal PdCoO$_2$ has been the subject of intense\ninterest for hosting exotic transport properties. Using first-principles\ntransport calculations and theoretical modeling, we reveal that the high\nelectrical conductivity of PdCoO$_2$ at room temperature originates from the\ncontributions of both high Fermi velocities, enabled by Pd $4d_{z^2}-5s$\nhybridization, and exceptionally weak electron-phonon coupling, which leads to\na coupling strength ($\\lambda=0.057$) that is nearly an order of magnitude\nsmaller than those of common metals. The abnormally weak electron-phonon\ncoupling in PdCoO$_2$ results from a low electronic density of states at the\nFermi level, as well as the large and strongly facetted Fermi surface with\nsuppressed Umklapp electron-phonon matrix elements. We anticipate that our work\nwill inform the design of unconventional metals with superior transport\nproperties."
    },
    {
        "anchor": "Blue-to-green single photons from InGaN/GaN dot-in-a-wire nanowire\n  ordered arrays: Single-photon emitters (SPEs) are at the basis of many applications for\nquantum information management. Semiconductor-based SPEs are best suited for\npractical implementations because of high design flexibility, scalability and\nintegration potential in practical devices. Single-photon emission from ordered\narrays of InGaN nano-disks embedded in GaN nanowires is reported. Intense and\nnarrow optical emission lines from quantum dot-like recombination centers are\nobserved in the blue-green spectral range. Characterization by electron\nmicroscopy, cathodoluminescence and micro-photoluminescence indicate that\nsingle photons are emitted from regions of high In concentration in the\nnano-disks due to alloy composition fluctuations. Single-photon emission is\ndetermined by photon correlation measurements showing deep anti-bunching minima\nin the second-order correlation function. The present results are a promising\nstep towards the realization of on-site/on-demand single-photon sources in the\nblue-green spectral range operating in the GHz frequency range at high\ntemperatures.",
        "positive": "High Phonon Scattering Rates Suppress Thermal Conductivity in\n  Hyperstoichiometric Uranium Dioxide: Uranium dioxide (UO$_2$), one of the most important nuclear fuels, can\naccumulate excess oxygen atoms as interstitial defects, which significantly\nimpacts thermal properties. In this study, thermal conductivities and inelastic\nneutron scattering measurements on UO$_2$ and UO$_{2+x}$ (x=0.3, 0.4, 0.8,\n0.11) were performed at low temperatures (2-300 K). The thermal conductivity of\nUO$_{2+x}$ is significantly suppressed compared to UO$_2$ except near the\nN\\'eel temperature TN= 30.8 K, where it is independent of x. Phonon\nmeasurements demonstrate that the heat capacities and phonon group velocities\nof UO$_2$ and UO$_{2+x}$ are similar and that the suppressed thermal\nconductivity in UO$_{2+x}$ results from high phonon scattering rates. These new\ninsights advance our fundamental understanding of thermal transport properties\nin advanced nuclear fuels."
    },
    {
        "anchor": "Ferroelectric atomic displacement in multiferroic tetragonal perovskite\n  Sr$_{1/2}$Ba$_{1/2}$MnO$_3$: We investigate the crystal structure in multiferroic tetragonal perovskite\nSr$_{1/2}$Ba$_{1/2}$MnO$_3$ with high accuracy of the order of 10$^{-3}$\nAngstrom for an atomic displacement. The large atomic displacement for Mn ion\nfrom the centerosymmetric position, comparable with the off-centering\ndistortion in the tetragonal ferroelectric BaTiO$_3$, is observed in the\nferroelectric phase ($T_\\mathrm{N}$ $\\leq$ $T$ $\\leq$ $T_\\mathrm{C}$). In stark\ncontrast, in the multiferroic phase ($T$ $\\leq$ $T_\\mathrm{N}$), the atomic\ndisplacement for Mn ion is suppressed, but those for O ions are enlarged. The\natomic displacements in the polar crystal structures are also analyzed in terms\nof the ferroelectric modes. In the ferroelectric phase, the atomic\ndisplacements are decomposed into dominant positive Slater, negative Last, and\nsmall positive Axe modes. The suppression of Slater and Last modes, the sign\nchange of Last mode, and the enlargement of Axe mode are found in the\nmultiferroic phase. The ferroelectric distortion is well reproduced by a\nfirst-principles calculation based on Berry phase method, providing an\nadditional information on competing mechanisms to induce the polarization,\nelectronic $p$-$d$ hybridization vs. magnetic exchange-striction.",
        "positive": "A new semiconducting perovskite alloy system made possible by gas-source\n  molecular beam epitaxy: Optoelectronic technologies are based on families of semiconductor alloys. It\nis rare that a new semiconductor alloy family is developed to the point where\nepitaxial growth is possible; since the 1950s, this has happened approximately\nonce per decade. Here we demonstrate epitaxial thin film growth of\nsemiconducting chalcogenide perovskite alloys in the Ba-Zr-S-Se system by\ngas-source molecular beam epitaxy (MBE). We stabilize the full range y = 0 ...\n3 of compositions BaZrS$_{(3-y)}$Se$_y$ in the perovskite structure, up to and\nincluding BaZrSe$_3$, by growing on BaZrS$_3$ epitaxial templates. The\nresulting films are environmentally stable and the direct band gap ($E_g$)\nvaries strongly with Se content, as predicted by theory, covering the range\n$E_g$ = 1.9 ... 1.4 eV for $y$ = 0 ... 3. This creates possibilities for\nvisible and near-infrared (VIS-NIR) optoelectronics, solid state lighting, and\nsolar cells using chalcogenide perovskites."
    },
    {
        "anchor": "The effect of relativity on stability of Copernicium phases, their\n  electronic structure and mechanical properties: The phase stability of the various crystalline structures of the super-heavy\nelement Copernicium was determined based on the first-principles calculations\nwith different levels of the relativistic effects. We utilized the Darwin term,\nmass-velocity, and spin-orbit interaction with the single electron framework of\nthe density functional theory while treating the exchange and correlation\neffects using local density approximations. It is found that the spin-orbit\ncoupling is the key component to stabilize the body-centered cubic ($bcc$)\nstructure over the hexagonal closed packed ($hcp$) structure, which is in\naccord with Sol. Stat. Comm. 152 (2012) 530, but in contrast to Sol. Stat.\nComm. 201 (2015) 88, Angew. Chem. 46 (2007) 1663, Handbook of Elemental Solids\nZ=104-112 (Springer 2015). It seems that the main role here is the correct\ndescription of the semi-core relativistic $6p_{1/2}$ orbitals. The all other\ninvestigated structures, i.e. face-centered cubic ($fcc$), simple cubic ($sc$)\nas well as rhombohedral ($rh$) structures are higher in energy. The criteria of\nmechanical stability were investigated based on the calculated elastic\nconstants, identifying the phase instability of $fcc$ and $rh$ structures, but\nsurprisingly confirm the stability of the energetically higher $sc$ structure.\nIn addition, the pressure-induced structural transition between two stable $sc$\nand $bcc$ phases has been detected. The ground-state $bcc$ structure exhibits\nthe highest elastic anisotropy from single elements of the Periodic table. At\nlast, we support the experimental findings that Copernicium is a metal.",
        "positive": "Spintronics and ferromagnetism in wide-band-gap semiconductors: Recent progress in understanding and controlling spintronic properties of\n(Ga,Mn)As and related compounds is contrasted to diverging experimental and\ntheoretical results concerning the origin of high temperature ferromagnetism\ndiscovered in an ample class of magnetically doped wide-band-gap\nsemiconductors."
    },
    {
        "anchor": "Effect of Dispersion and Different Carrier Transitions on Absorption\n  Characteristics of GaAs: One of the basic optoelectronic characteristics is the absorption of any\noptoelectronic device or material. We present the characteristics of pure GaAs\nand the deviation of ideal spectra. Due to crystal defects, vacancies,\nimpurities, etc., energy states exist in the semiconductor other than the\nallowed bands (conduction and valence bands). In this research, the effect of\ntransitions between these states on absorption spectra and how the absorption\ncoefficients change with the density and location of those states are analyzed\nnumerically. Among the cases of 0.07 eV, 0.12 eV, and 0.17 eV with the density\nof 2%, 5%, 10%, 20%, and 30%, the minimum deviation occurs for the states\nlocated 0.07 eV below the conduction band and when the energy states have the\nminimum density of 2% and the deviation increases for the cases of 0.12 eV and\n0.17 eV with higher densities.",
        "positive": "Dose-dependent isotherm of Kr adsorption on heterogeneous bundles of\n  closed single-walled carbon nanotubes: We present 77 K isotherms of krypton adsorption on bundles of closed\nhighly-pure HiPco single-walled carbon nanotubes (SWCNTs). Two volumetric\nadsorption protocols were used, one with an increasing Kr dose per injection\n(IAD), one with a constant dose (CAD). Detailed microstructural examination\nshowed that the SWCNTs combine into small bundles (of 25-30 SWCNTs) which are\nheterogeneous in diameter with a consequential range of interstitial channel\n(IC) shapes and sizes. The IC-sites are the subnanoscaled pores with\nalternating enlargements and constrictions along the tube axes. This results in\nadsorption dosing (AD) dependent characteristics of the low-pressure region of\nthe isotherm. In the IAD protocol the switch-back behavior of the isotherm\nstemmed from metastable adsorption. Using the CAD protocol, different branches\nare observed. Well-pronounced substeps were established which we interpret as\ncorresponding to the formation of various phases of confined Kr with different\natoms arrangement. The height of a given substep obtained in different\nmeasurements depends on the AD value which can strongly influence the\npopulation of the site. Some substeps existing only for certain values of AD\nsuggests the existence of a certain selectivity or of a preferential phase\nformation according to this value."
    },
    {
        "anchor": "Machine learning-enabled high-entropy alloy discovery: High-entropy alloys are solid solutions of multiple principal elements,\ncapable of reaching composition and feature regimes inaccessible for dilute\nmaterials. Discovering those with valuable properties, however, relies on\nserendipity, as thermodynamic alloy design rules alone often fail in\nhigh-dimensional composition spaces. Here, we propose an active-learning\nstrategy to accelerate the design of novel high-entropy Invar alloys in a\npractically infinite compositional space, based on very sparse data. Our\napproach works as a closed-loop, integrating machine learning with\ndensity-functional theory, thermodynamic calculations, and experiments. After\nprocessing and characterizing 17 new alloys (out of millions of possible\ncompositions), we identified 2 high-entropy Invar alloys with extremely low\nthermal expansion coefficients around 2*10-6 K-1 at 300 K. Our study thus opens\na new pathway for the fast and automated discovery of high-entropy alloys with\noptimal thermal, magnetic and electrical properties.",
        "positive": "Role of interface in ferromagnetism of (Zn,Co)O films: We demonstrate that room temperature ferromagnetic response (RT FR) of ZnCoO\nfilms grown at low temperature by the Atomic layer Deposition (ALD) method is\ndue to Co metal accumulations at the ZnCoO/substrate interface region. The\naccumulated experimental evi evidences allow us to reject several other\nexplanations of this effect in our samples, despite the fact that some of them\nare likely to be responsible for the low temperature FM in this class of the\nmaterial."
    },
    {
        "anchor": "Revisiting longitudinal optical modes in materials with plasmon and\n  plasmon-like absorptions -- SrTiO$_3$ and $\u03b2$-Ga$_2$O$_3$: We investigate exemplary the longitudinal optical (LO) mode order in\ncompounds with a plasmon or plasmon-like phonon mode and additional phonon\nmodes. When the oscillator strength of the plasmon or plasmon-like mode is\ngradually increased, a reordering of the modes takes place. Since it is not\npossible in crystals with orthorhombic or higher symmetry that a LO mode\ncrosses a transverse optical (TO) mode's position, this reordering takes place\nvia mode hybridization. During this mode hybridization, the plasmon or\nplasmon-like LO mode gradually becomes the originally higher situated LO mode\nwhile the latter morphs into the former. As a consequence, an inner (LO-TO) and\nan outer (TO-LO) mode pair is formed. This process continues until the LO\noscillator strength is so high that all other phonons are inverted and form\nLO-TO pairs within the outer TO-LO mode pair of the plasmon or plasmon-like\nmode. These insights can be readily transferred to other semiconductors or many\nmode materials with reststrahlen bands and allow simple mode assignments. These\nmode assignments will help to understand the nature of surface modes of\nstructured layers of these materials for application of surface plasmon\npolariton and surface phonon polaritons based metamaterials.",
        "positive": "Negative Hydration Expansion in ZrW2O8: Microscopic Mechanism, Spaghetti\n  Dynamics, and Negative Thermal Expansion: We use a combination of X-ray diffraction, total scattering and quantum\nmechanical calculations to determine the mechanism responsible for\nhydration-driven contraction in ZrW$_2$O$_8$. Inclusion of H$_2$O molecules\nwithin the ZrW$_2$O$_8$ network drives the concerted formation of new W--O\nbonds to give one-dimensional (--W--O--)$_n$ strings. The topology of the\nZrW$_2$O$_8$ network is such that there is no unique choice for the string\ntrajectories: the same local changes in coordination can propagate with a large\nnumber of different periodicities. Consequently, ZrW$_2$O$_8$ is heavily\ndisordered, with each configuration of strings forming a dense aperiodic\n`spaghetti'. This new connectivity contracts the unit cell \\emph{via} large\nshifts in the Zr and W atom positions. Fluctuations of the undistorted parent\nstructure towards this spaghetti phase emerge as the key NTE phonon modes in\nZrW$_2$O$_8$ itself. The large relative density of NTE phonon modes in\nZrW$_2$O$_8$ actually reflect the degeneracy of volume-contracting spaghetti\nexcitations, itself a function of the particular topology of this remarkable\nmaterial."
    },
    {
        "anchor": "Robustness of ferromagnetism in (In,Fe)Sb diluted magnetic semiconductor\n  to variation of charge carrier concentration and Fermi level position: The influence of He+ ion irradiation on the transport and magnetic properties\nof epitaxial layers of a diluted magnetic semiconductor (DMS) (In,Fe)Sb, a\ntwo-phase (In,Fe)Sb composite and a nominally undoped InSb semiconductor has\nbeen investigated. In all layers, a conductivity type conversion from the\ninitial n-type to the ptype has been found. The ion fluence at which the\nconversion occurs depends on the Fe concentration in the InSb matrix.\nMagnetotransport properties of the two-phase (In,Fe)Sb layer are strongly\naffected by ferromagnetic Fe inclusions. An influence of the number of\nelectrically active radiation defects on the magnetic properties of the\nsingle-phase In0.75Fe0.25Sb DMS has been found. At the same time, the results\nshow that the magnetic properties of the In0.75Fe0.25Sb DMS are quite resistant\nto significant changes of the charge carrier concentration and the Fermi level\nposition. The results confirm a weak interrelation between the ferromagnetism\nand the charge carrier concentration in (In,Fe)Sb.",
        "positive": "Insights into the structural, electronic and optical properties of\n  X$_2$MgZ$_4$($X=$ Sc, Y; $Z=$ S, Se) spinel compounds: Materials for the\n  future optoelectronic applications: Direct bandgap bulk materials are very important for the optical\napplications. It is therefore important to predict new materials with the\ndesired properties. In the present work, density functional theory is applied\nto study different physical properties of X$_2$MgZ$_4$($X=$ Sc, Y; $Z=$ S, Se)\nspinel compounds. Generalized gradient approximation is used to analyze the\nstructural and elastic parameters while modified Becke Johnson exchange\npotential is applied to calculate electric band profiles and optical\nproperties. All the studied compounds are stable in the cubic structure. Also\nthe energy bandgap is of direct nature. Therefore these compounds can find\nuseful applications in the optoelectrics devices. Optical properties of the\ncompounds are studied in terms of dielectric function, refractive index,\nextinction coefficient, optical conductivity and reflectivity. The transport\nparameters like electrical conductivity, Seebeck coefficient, and thermal\nconductivity are also evaluated."
    },
    {
        "anchor": "Optical and Electronic Properties of CdTe Quantum Dots in their Freezed\n  Solid Matrix Phase and Solution Phase: The present work deals with the comparison of sizes, optical and electronic\nproperties of COOH functionalized CdTe quantum dots (QDs) in freezed solid\npolymeric (polyvinyl alcohol (PVA) matrix and in solution phase (water). PVA\nhas been chosen as host material for guest CdTe QDs because of its unique\nproperties like hydrophilicity, good thermo stability, and easy process\nability. Experimental absorption, emission, X-Ray diffraction spectra and\nelectronic band gap have been studied by UV-Vis absorption, luminescence and\nX-Ray diffraction spectroscopy. The smaller size of CdTe QDs in solid PVA\npolymer matrix (~ 6 nm) and larger band gap of ~9.5 eV validates their quantum\nconfinement regime in freezed solid phase. The smaller particle size in solid\nphase compared to that of the particle size in its solution phase (8 nm)\nvalidates the non existence of agglomeration in solid phase. Appearance of high\nintense and wide luminescence emission in solid form proves the strong\ncandidature of CdTe QDs as promising sensors for today's optoelectronic and\nbiomedical industry.",
        "positive": "Soft mode anisotropy in negative thermal expansion material ReO$_3$: We use a symmetry-motivated approach to analyse neutron pair distribution\nfunction data to investigate the mechanism of negative thermal expansion (NTE)\nin ReO$_3$. This analysis shows that the local structure of ReO$_3$ is\ndominated by an in-phase octahedral tilting mode and that the octahedral units\nare far less flexible to scissoring type deformations than the octahedra in the\nrelated compound ScF$_3$. These results support the idea that structural\nflexibility is an important factor in NTE materials, allowing the phonon modes\nthat drive a volume contraction of the lattice to occupy a greater volume in\nreciprocal space. The lack of flexibility in ReO$_3$ restricts the NTE-driving\nphonons to a smaller region of reciprocal space, limiting the magnitude and\ntemperature range of NTE. In addition, we investigate the thermal expansion\nproperties of the material at high temperature and do not find the reported\nsecond NTE region. Finally, we show that the local fluctuations, even at\nelevated temperatures, respect the symmetry and order parameter direction of\nthe observed $P4/mbm$ high pressure phase of ReO$_3$. The result indicates that\nthe motions associated with rigid unit modes are highly anisotropic in these\nsystems."
    },
    {
        "anchor": "On the mechanisms of precipitation of graphene on nickel thin films: Growth on transition metal substrates is becoming a method of choice to\nprepare large-area graphene foils. In the case of nickel, where carbon has a\nsignificant solubility, such a growth process includes at least two elementary\nsteps: (1) carbon dissolution into the metal, and (2) graphene precipitation at\nthe surface. Here, we dissolve calibrated amounts of carbon in nickel films,\nusing carbon ion implantation, and annealing at 725 \\circ or 900 \\circ. We then\nuse transmission electron microscopy to analyse the precipitation process in\ndetail: the latter appears to imply carbon diffusion over large distances and\nat least two distinct microscopic mechanisms.",
        "positive": "Structural correlations in the enhancement of ferroelectric property of\n  Sr doped BaTiO3: The effect of Sr doping in BaTiO3 (BTO) with nominal compositions\nBa0.80Sr0.20TiO3 (BSTO) have been explored in its structural, lattice\nvibration, dielectric, ferroelectric and electrocaloric properties. The\ntemperature dependent dielectric results elucidate the enhancement in\ndielectric constant and exhibit three frequency independent transitions around\n335, 250 and 185 K which are related to different structural transitions. All\nthese transitions occur at lower temperature as compared with pristine BTO,\nhowever; remnant electric polarization (P) of BSTO is much higher than in BTO.\nThe value of P is around 5 microC/cm2 at room temperature and the maximum P\naround 8 microC/cm2 is observed at tetragonal to orthorhombic and orthorhombic\nto rhombohedral transitions. The electro-caloric effect shows the maximum\nadiabatic change in temperature deltaT approx 0.24 K at cubic to tetragonal\ntransition. The temperature dependent synchrotron X-ray diffraction and Raman\nresults shows correlations between P, crystal structure and lattice vibrations.\nOur results demonstrate the enhancement in ferroelectric properties of BTO with\nSr doping. The origin of the enhancement in ferroelectric property is also\ndiscussed which is related to the appearance of superlattice peak around room\ntemperature due to TiO6 octahedral distortion. These enhanced properties would\nbe useful to design lead free high quality ferroelectric and piezoelectric\nmaterials."
    },
    {
        "anchor": "Magnetic properties of disordered polycrystalline bulk Sm$ _{2} $NiMnO$\n  _{6} $ double perovskite: The structural, electronic and magnetic properties of anti-site disordered\nSm$ _{2} $NiMnO$ _{6} $ double perovskite has been studied. RE$_{2}$NiMnO$_{6}$\n(RE: rare-earth) ordered double perovskite is commonly believed to show two\ndistinct magnetic phase transitions viz, paramagnetic to ferromagnetic (FM)\ntransition at T = T$ _{C} $ due to Ni-O-Mn super exchange interaction and\nanother transition at T = T$ _{d} $ due to coupling of RE spins with Ni-Mn\nnetwork. In our present study, we have observed that the presence of intrinsic\nB-site disorder results in an additional antiferromagnetic (AFM) coupling,\nmediated via Ni-O-Ni and Mn-O-Mn local bond pairs. As a consequence, the\nmagnetic behavior of SNMO comprises of co-existing FM-AFM phases, which are\nrespectively governed by the anti-site ordered and disordered structures. Field\ndependent inverted cusp like trend in M(T) and two step reversible loop\nbehavior in M(H) measurements indicate the presence of competing FM-AFM phases\nover a wide range of temperature values (T$ _{d} < $ T $ < $ T$ _{C} $).",
        "positive": "Spin-pump-induced spin transport in a thermally-evaporated pentacene\n  film: We report the spin-pump-induced spin transport properties of a pentacene film\nprepared by thermal evaporation. In a palladium(Pd)/pentacene/Ni80Fe20\ntri-layer sample, a pure spin-current is generated in the pentacene layer by\nthe spin-pumping of Ni80Fe20, which is independent of the conductance mismatch\nproblem in spin injection. The spin current is absorbed into the Pd layer,\nconverted into a charge current with the inverse spin-Hall effect in Pd, and\ndetected as an electromotive force. This is clear evidence for the pure spin\ncurrent at room temperature in pentacene films prepared by thermal evaporation."
    },
    {
        "anchor": "Strong On-Chip Microwave Photon-Magnon Coupling Using Ultra-low Damping\n  Epitaxial Y3Fe5O12 Films at 2 Kelvin: Y3Fe5O12 is arguably the best magnetic material for magnonic quantum\ninformation science (QIS) because of its extremely low damping. We report\nultralow damping at 2 K in epitaxial Y3Fe5O12 thin films grown on a diamagnetic\nY3Sc2Ga3O12 substrate that contains no rare-earth elements. Using these\nultralow damping YIG films, we demonstrate for the first time strong coupling\nbetween magnons in patterned YIG thin films and microwave photons in a\nsuperconducting Nb resonator. This result paves the road towards scalable\nhybrid quantum systems that integrate superconducting microwave resonators, YIG\nfilm magnon conduits, and superconducting qubits into on-chip QIS devices.",
        "positive": "Graphene Oxide and Polymer Humidity Micro-Sensors Prepared by Carbon\n  Beam Writing: In this study, novel flexible micro-scale humidity sensors were directly\nfabricated in graphene oxide (GO) and polyimide (PI) using ion beam writing\nwithout any further modifications, and then successfully tested in an\natmospheric chamber. Two low fluences of carbon ions with an energy of 5 MeV\nwere used, and structural changes in the irradiated materials were expected.\nThe shape and structure of prepared micro-sensors were studied using scanning\nelectron microscopy (SEM). The structural and compositional changes in the\nirradiated area were characterized using micro-Raman spectroscopy, X-ray\nphotoelectron spectroscopy (XPS), Rutherford back-scattering spectroscopy\n(RBS), energy-dispersive X-ray spectroscopy (EDS), and elastic recoil detection\nanalysis (ERDA) spectroscopy. The sensing performance was tested at a relative\nhumidity (RH) ranging from 5 % to 60 %, where the electrical conductivity of PI\nvaried by three orders of magnitude, and the electrical capacitance of GO\nvaried in the order of pico-farads. In addition, the PI sensor has proven\nlong-term sensing stability in air. We demonstrated a novel method of ion\nmicro-beam writing to prepare flexible micro-sensors that function over a wide\nrange of humidity and have good sensitivity and great potential for widespread\napplications."
    },
    {
        "anchor": "Double-Rashba materials for nanocrystals with bright ground-state\n  excitons: While nanoscale semiconductor crystallites provide versatile fluorescent\nmaterials for light-emitting devices, such nanocrystals suffer from the \"dark\nexciton\"$\\unicode{x2014}$an optically inactive electronic state into which the\nnanocrystal relaxes before emitting. Recently, a theoretical mechanism was\ndiscovered that can potentially defeat the dark exciton. The Rashba effect can\ninvert the order of the lowest-lying levels, creating a bright excitonic ground\nstate. To identify materials that exhibit this behavior, here we perform an\nextensive high-throughput computational search of two large open-source\nmaterials databases. Based on a detailed understanding of the Rashba mechanism,\nwe define proxy criteria and screen over 500,000 solids, generating 173\npotential \"bright-exciton\" materials. We then refine this list with\nhigher-level first-principles calculations to obtain 28 candidates. To confirm\nthe potential of these compounds, we select five and develop detailed\neffective-mass models to determine the nature of their lowest-energy excitonic\nstate. We find that four of the five solids (BiTeCl, BiTeI, Ga$_2$Te$_3$, and\nKIO$_3$) can yield bright ground-state excitons. Our approach thus reveals\npromising materials for future experimental investigation of bright-exciton\nnanocrystals.",
        "positive": "Supplemental Material for \"High Contrast X-ray Speckle from Atomic-Scale\n  Order in Liquids and Glasses\": This supplemental material gives additional detail on Experimental Methods\nand Hard X-ray FEL Source Characteristics, Calculation of Maximum Speckle\nContrast, Extracting Contrast of Weak Speckle Patterns, Estimated Temperature\nIncrease from X-ray Absorption, Split-Pulse XPCS Feasibility, and Sample\nDisturbance During Single Pulses."
    },
    {
        "anchor": "van der Waals forces stabilize low-energy polymorphism in B2O3:\n  Implications for the crystallization anomaly: The cohesive energies and structural properties of recently predicted, and\nnever synthesized, B$_2$O$_3$ polymorphs are investigated from first principles\nusing density functional theory and high-accuracy many-body methods, namely,\nthe random phase approximation and quantum Monte Carlo. We demonstrate that the\nvan der Waals forces play a key role in making the experimentally known\npolymorph (B$_2$O$_3$-I) the lowest in energy, with many competing metastable\nstructures lying only a few kcal/mol above. Remarkably, all metastable crystals\nare comparable in energy and density to the glass, while having anisotropic and\nmechanically soft structures. Furthermore, the best metastable polymorph\naccording to our stability criteria has a structural motif found in both the\nglass and a recently synthesized borosulfate compound. Our findings provide new\nperspectives for understanding the B$_2$O$_3$ anomalous behavior, namely, its\npropensity to vitrify in a glassy structure drastically different from the\nknown crystal.",
        "positive": "Auto-oscillation threshold and line narrowing in MgO-based spin-torque\n  oscillators: We present an experimental study of the power spectrum of current-driven\nmagnetization oscillations in MgO tunnel junctions under low bias. We find the\nexistence of narrow spectral lines, down to 8 MHz in width at a frequency of\n10.7 GHz, for small applied fields with clear evidence of an auto-oscillation\nthreshold. Micromagnetics simulations indicate that the excited mode\ncorresponds to an edge mode of the synthetic antiferromagnet."
    },
    {
        "anchor": "Elastic, electronic and optical properties of hypothetical SnNNi3 and\n  CuNNi3 in comparison with superconducting ZnNNi3: The elastic, electronic and optical properties of MNNi3 (M= Zn, Sn and Cu)\nhave been calculated using the plane-wave ultrasoft pseudopotential technique\nwhich is based on the first-principles density functional theory (DFT) with\ngeneralized gradient approximation (GGA). The optimized lattice parameters,\nindependent elastic constants (C11, C12, and C44), bulk modulus B,\nCompressibility K, shear modulus G, and Poisson's ratio \\u{psion}, as well as\nthe band structures, total and atom projected densities of states and finally\nthe optical properties of MNNi3 have been evaluated and discussed. The\nelectronic band structures of the two hypothetical compounds show metallic\nbehavior just like the superconducting ZnNNi3. Using band structures, the\norigin of features that appear in different optical properties of all the three\ncompounds have been discussed. The large reflectivity of the predicted\ncompounds in the low energy region might be good candidate materials as a\ncoating to avoid solar heating. Key words: MNNi3, Ab initio calculations,\nElastic properties, Electronic band structure, Optical properties.",
        "positive": "Large transverse thermoelectric figure of merit in a Dirac semimetal: Thermoelectric (TE) conversion in conducting materials is of eminent\nimportance for providing renewable energy and solid-state cooling. Although\ntraditionally, the Seebeck effect plays a key role for the TE figure of merit\nzST, it encounters fundamental constraints hindering its conversion efficiency.\nMost notably, there are the charge compensation of electrons and holes that\ndiminishes this effect, and the intertwinement of the corresponding electrical\nand thermal conductivities through the Wiedemann-Franz (WF) law which makes\ntheir independent optimization in zST impossible. Here, we demonstrate that in\nthe Dirac semimetal Cd3As2 the Nernst effect, i.e., the transverse counterpart\nof the Seebeck effect, can generate a large TE figure of merit zNT. At room\ntemperature, zNT = 0.5 in a small field of 2 T; it significantly surmounts its\nlongitudinal counterpart zST for any field and further increases upon warming.\nA large Nernst effect is generically expected in topological semimetals,\nbenefiting from both the bipolar transport of compensated electrons and holes\nand their high mobilities. In this case, heat and charge transport are\northogonal, i.e., not intertwined by the WF law anymore. More importantly,\nfurther optimization of zNT by tuning the Fermi level to the Dirac node can be\nanticipated due to not only the enhanced bipolar transport, but also the\nanomalous Nernst effect arising from a pronounced Berry curvature. A\ncombination of the former topologically trivial and the latter nontrivial\nadvantages promises to open a new avenue towards high-efficient transverse\nthermoelectricity."
    },
    {
        "anchor": "Graphite in the bi-layer regime: in-plane transport: An interplay between the increase in the number of carriers and the decrease\nin the scattering time is expected to result in a saturation of the in-plane\nresistivity, $\\rho_{ab}$, in graphite above room temperature. Contrary to this\nexpectation, we observe a pronounced increase in $\\rho_{ab}$ in the interval\nbetween 300 and 900 K. We provide a theory of this effect based on intervalley\nscattering of charge carriers by high-frequency, graphene-like optical phonons.",
        "positive": "Topological quantisation and gauge invariance of charge transport in\n  liquid insulators: According to the Green-Kubo theory of linear response, the conductivity of an\nelectronically gapped liquid can be expressed in terms of the time correlations\nof the adiabatic charge flux, which is determined by the atomic velocities and\nBorn effective charges. We show that topological quantisation of adiabatic\ncharge transport and gauge invariance of transport coefficients allow one to\nrigorously express the electrical conductivity of an insulating fluid in terms\nof integer-valued, scalar, and time-independent atomic oxidation numbers,\ninstead of real-valued, tensor, and time-dependent Born charges."
    },
    {
        "anchor": "Phase diagram of silicon from atomistic simulations: In this letter we present a calculation of the temperature-pressure phase\ndiagram of Si in a range of pressures covering from -5 to 20 GPa and\ntemperatures up to the melting point. The phase boundaries and triple points\nbetween the diamond, liquid, $\\beta$-Sn and ${Si}_{34}$ clathrate phases are\nreported. We have employed efficient simulation techniques to calculate free\nenergies and to numerically integrate the Clausius-Clapeyron equation, combined\nwith a tight binding model capable of an accuracy comparable to that of\nfirst-principles methods. The resulting phase diagram agrees well with the\navailable experimental data.",
        "positive": "Statistical Thermodynamics and Ordering Kinetics of D019-Type Phase:\n  Application of the Models for H.C.P.-Ti-Al Alloy: Using the self-consistent field approximation, the static concentration waves\napproach and the Onsager-type kinetics equations, the descriptions of both the\nstatistical thermodynamics and the kinetics of an atomic ordering of D019 phase\nare developed and applied for h.c.p.-Ti-Al alloy. The model of order-disorder\nphase transformation describes the phase transformation of h.c.p. solid\nsolution into the D019 phase. Interatomic-interaction parameters are estimated\nfor both approximations: one supposes temperature-independent\ninteratomic-interaction parameters, while the other one includes the\ntemperature dependence of interchange energies for Ti-Al alloy. The partial\nTi-Al phase diagrams (equilibrium compositions of the coexistent ordered and\ndisordered phases) are evaluated for both cases. The equation for the time\ndependence of D019- type long-range order (LRO) parameter is analyzed. The\ncurves (showing the LRO parameter evolution) are obtained numerically for both\ntemperature-independent interaction energies and temperature-dependent ones.\nTemperature dependence of the interatomic-interaction energies accelerates the\nLRO relaxation and diminishes a spread of the values of instantaneous and\nequilibrium LRO parameters versus the temperature. Both\nstatistical-thermodynamics and kinetics results show that equilibrium LRO\nparameter for a non-stoichiometry (where an atomic fraction of alloying\ncomponent is more than 0.25) can be higher than for a stoichiometry at high\ntemperatures. The experimental phase diagram confirms the predicted (ordered or\ndisordered) states for h.c.p.-Ti-Al."
    },
    {
        "anchor": "Electron localization and possible phase separation in the absence of a\n  charge density wave in single-phase 1T-VS$_2$: We report on a systematic study of the structural, magnetic and transport\nproperties of high-purity 1T-VS$_2$ powder samples prepared under high\npressure. The results differ notably from those previously obtained by\nde-intercalating Li from LiVS$_2$. First, no Charge Density Wave (CDW) is found\nby transmission electron microscopy down to 94 K. Though, \\textit{ab initio}\nphonon calculations unveil a latent CDW instability driven by an acoustic\nphonon softening at the wave vector ${\\bf q}_{CDW} \\approx$ (0.21,0.21,0)\npreviously reported in de-intercalated samples. A further indication of latent\nlattice instability is given by an anomalous expansion of the V-S bond distance\nat low temperature. Second, infrared optical absorption and electrical\nresistivity measurements give evidence of non metallic properties, consistent\nwith the observation of no CDW phase. On the other hand, magnetic\nsusceptibility and NMR data suggest the coexistence of localized moments with\nmetallic carriers, in agreement with \\textit{ab initio} band structure\ncalculations. This discrepancy is reconciled by a picture of electron\nlocalization induced by disorder or electronic correlations leading to a phase\nseparation of metallic and non-metallic domains in the nm scale. We conclude\nthat 1T-VS$_2$ is at the verge of a CDW transition and suggest that residual\nelectronic doping in Li de-intercalated samples stabilizes a uniform CDW phase\nwith metallic properties.",
        "positive": "Theory of Defect-Induced Kondo Effect in Graphene: Numerical\n  Renormalization Group Study: An effective model that describes the Kondo effect due to a point defect in\ngraphene is developed, taking account of the electronic state and the lattice\nstructure of the defect. It is shown that this model can be transformed into a\nsingle-channel pseudogap Anderson model with a finite chemical potential. On\nthe basis of the numerical renormalization group method, it is clarified that\nthe experimentally observed gate-voltage dependence of the Kondo temperature is\nunderstood in this framework."
    },
    {
        "anchor": "Microscopic mechanism for asymmetric charge distribution in Rashba-type\n  surface states and the origin of the the energy splitting scale: Microscopic mechanism for the Rashba-type band splitting is examined in\ndetail. We show how asymmetric charge distribution is formed when local orbital\nangular momentum (OAM) and crystal momentum get interlocked due to surface\neffects. An electrostatic energy term in the Hamiltonian appears when such OAM\nand crystal momentum dependent asymmetric charge distribution is placed in an\nelectric field produced from an inversion symmetry breaking (ISB). Analysis by\nusing an effective Hamiltonian shows that, as the atomic spin-orbit coupling\n(SOC) strength increases from weak to strong, originally OAM-quenched states\nevolve into well-defined chiral OAM states and then to total angular momentum\nJ-states. In addition, the energy scale of the band splitting changes from\natomic SOC energy to electrostatic energy. To confirm the validity of the\nmodel, we study OAM and spin structures of Au(111) system by using an effective\nHamiltonian for the d-orbitals case. As for strong SOC regime, we choose\nBi2Te2Se as a prototype system. We performed circular dichroism angle resolved\nphotoemission spectroscopy experiments as well as first-principles\ncalculations. We find that the effective model can explain various aspects of\nspin and OAM structures of the system.",
        "positive": "Non-affine fluctuations and the Statistics of Defect Precursors in the\n  Planar Honeycomb Lattice: Certain localised displacement fluctuations in the planar honeycomb lattice\nmay be identified as precursors to topological defects. We show that these\nfluctuations are among the most pronounced {\\em non-affine} distortions of an\nelemental coarse graining volume of the honeycomb structure at non zero\ntemperatures. We obtain the statistics of these precursor modes in the\ncanonical ensemble, evaluating exactly their single point and two-point\nspatio-temporal distributions, for a lattice with harmonic nearest neighbour\nand next near neighbour bonds. As the solid is destabilised by tuning\ninteractions, the precursor fluctuations diverge and correlations become\nlong-lived and long-ranged."
    },
    {
        "anchor": "Multiferroic Thermodynamics: We have studied the thermodynamic properties of a multiferroic that couples\nferromagnetic and ferroelectric order. Some of the results are independent of\nthe form of the free energy. We calculate the temperature dependence of the\nelectric, magnetic, and magnetoelectric susceptibilities. The cross\nsusceptibility has a temperature dependence related to the mixed (with respect\nto E and B) derivatives of the specific heat. The phase transitions are all\nsecond order. In particular, the phase boundary T$_M$(E), where T$_M$ is the\nlower magnetic transition as a function of electric field, is described by the\nEhrenfest relation. The magnetoelectric susceptibility is nonzero only below\nthe lower of the two transition temperatures. We study the properties of the\nspecific heat, with and without the inclusion of gaussian fluctuations. The\nperturbative renormalization group is used to understand the fixed points of\nthe theory, and we include a discussion of the effect inhomogeneities have for\nthis model.",
        "positive": "Persistent spin texture enforced by symmetry: Persistent spin texture (PST) is the property of some materials to maintain a\nuniform spin configuration in the momentum space. This property has been\npredicted to support an extraordinarily long spin lifetime of carriers\npromising for spintronics applications. The PST is known to emerge when the\nstrengths of two dominant spin-orbit couplings, the Rashba and linear\nDresselhaus, are equal. This condition, however, is not trivial to achieve and\nrequires tuning the Rashba and Dresselhaus parameters, as has been demonstrated\nwith semiconductor quantum-well structures. Here we predict that there exist a\nclass of non-centrosymmetric bulk materials where the PST is enforced by the\nnon-symmorphic space group symmetry of the crystal. Around certain high\nsymmetry points in the Brillouin zone, the sublattice degrees of freedom impose\na constraint on the effective spin-orbit field, which remains independent of\nthe momentum orientation and thus maintains the PST. We illustrate this\nbehavior using density-functional theory calculations for a handful of\npromising candidates accessible experimentally. Among them is the ferroelectric\noxide BiInO3-a wide band gap semiconductor which sustains a PST around the\nconduction band minimum. Our results broaden the range of materials, which can\nbe employed in spintronics."
    },
    {
        "anchor": "Machine learning aided materials design platform for predicting the\n  mechanical properties of Na-ion solid-state electrolytes: Na-ion solid-state electrolytes (Na-SSE) exhibit high potential for\nelectrical energy storage owing to their high energy densities and low\nmanufacturing cost. However, their mechanical properties critical to maintain\nstructural stability at the interface are still insufficiently understood. In\nthis study, a machine learning based regression model was developed for\npredicting the mechanical properties of Na-SSEs. As a training set, 12,361\nmaterials were obtained from a well-known materials database (Materials\nProject) and were represented with their respective chemical and structural\ndescriptors. The developed surrogate model exhibited a remarkable accuracy (R2\nscore) of 0.72 and 0.87, with a mean absolute error of 11.8 GPa and 15.3 GPa\nfor the shear and bulk modulus, respectively. This model was then applied to\npredict the mechanical properties of 2,432 Na-SSEs, the properties of which\nhave been validated with first principles calculations. Finally, the\noptimization process was performed to develop an ideal materials screening\nplatform by adding the new minimized dataset, wherein the prediction\nuncertainty is reduced. We believe that the platform proposed in this study can\naccelerate the search for Na-SSEs with ideal mechanical properties at minimum\ncost.",
        "positive": "Platinum-absorbed Defective 2D Monolayer Boron Nitride: A Promising\n  Electrocatalyst for O2 Reduction Reaction: The large bandgap and strong covalent bonds of hexagonal boron nitride (hBN)\nhad long been thought to be chemically inert. Due to its inertness with\nsaturated robust covalent bonds, the pristine 2D monolayer hBN cannot be\nfunctionalized for applications of energy conversion. Therefore, it is\nnecessary to make the 2D hBN chemically reactive for potential applications.\nHere, we have computationally designed a single nitrogen (N) and boron (B)\ndi-vacancy of the 2D monolayer hBN, noted by VBN defective-BN (d-BN), to\nactivate the chemical reactivity, which is an effective strategy to use the\nd-BN for potential applications. Single Pt atom absorbed on the defective area\nof the VBN d-BN acts as a single-atom catalyst which exhibits distinctive\nperformances for O2 reduction reaction (ORR). First-principles based\ndispersion-corrected periodic hybrid Density Functional Theory (DFT-D) method\nhas been employed to investigate the equilibrium structure and properties of\nthe Pt-absorbed 2D defective boron nitride (Pt-d-BN). The present study shows\nthe semiconducting character of Pt-d-BN with an electronic bandgap of 1.30 eV,\nwhich is an essential aspect of the ORR. The ORR mechanism on the surface of 2D\nmonolayer Pt-d-BN follows a 4e-reduction route because of the low barriers to\nOOH formation and dissociation, H2O2 instability and water production at the\nPt-d-BN surface. Here, both the dissociative and associative ORR mechanisms\nhave been investigated, and it is found that results for both mechanisms with\nthe ORR pathways are almost equally favorable. Therefore, it can be mentioned\nhere that the 2D monolayer Pt-d-BN exhibits a high selectivity for the\nfour-electron reduction pathway. According to the calculations of the relative\nadsorption energy of each step in ORR, the Pt-d-BN is anticipated to exhibit\nsubstantial catalytic activity."
    },
    {
        "anchor": "Stochastic phase-field simulations of symmetric alloy solidification: We study initial transient stages in directional solidification by means of a\nnon-variational phase field model with fluctuations. This model applies for the\nsymmetric solidification of dilute binary solutions and does not invoke\nfluctuation-dissipation theorem to account for the fluctuation statistics. We\ndevote our attention to the transient regime during which concentration\ngradients are building up and fluctuations act to destabilize the interface. To\nthis end, we calculate both the temporally dependent growth rate of each mode\nand the power spectrum of the interface evolving under the effect of\nfluctuations. Quantitative agreement is found when comparing the phase-field\nsimulations with theoretical predictions.",
        "positive": "Self-consistent phonon calculations of lattice dynamical properties in\n  cubic SrTiO$_{3}$ with first-principles anharmonic force constants: We present an \\textit{ab initio} framework to calculate anharmonic phonon\nfrequency and phonon lifetime that is applicable to severely anharmonic\nsystems. We employ self-consistent phonon (SCPH) theory with microscopic\nanharmonic force constants, which are extracted from density-functional\ncalculations using the least absolute shrinkage and selection operator\ntechnique. We apply the method to the high-temperature phase of SrTiO$_{3}$ and\nobtain well-defined phonon quasiparticles that are free from imaginary\nfrequencies. Here we show that the anharmonic phonon frequency of the\nantiferrodistortive mode depends significantly on the system size near the\ncritical temperature of the cubic-to-tetragonal phase transition. By applying\nperturbation theory to the SCPH result, phonon lifetimes are calculated for\ncubic SrTiO$_{3}$, which are then employed to predict lattice thermal\nconductivity using the Boltzmann transport equation within the relaxation-time\napproximation. The presented methodology is efficient and accurate, paving the\nway toward a reliable description of thermodynamic, dynamic, and transport\nproperties of systems with severe anharmonicity, including thermoelectric,\nferroelectric, and superconducting materials."
    },
    {
        "anchor": "Field-free spin-orbit torque switching through domain wall motion: Deterministic current-induced spin-orbit torque (SOT) switching of\nmagnetization in a heavy transition metal/ferromagnetic metal/oxide magnetic\nheterostructure with the ferromagnetic layer being perpendicularly-magnetized\ntypically requires an externally-applied in-plane field to break the switching\nsymmetry. We show that by inserting an in-plane magnetized ferromagnetic layer\nCoFeB underneath the conventional W/CoFeB/MgO SOT heterostructure,\ndeterministic SOT switching of the perpendicularly-magnetized top CoFeB layer\ncan be realized without the need of in-plane bias field. Kerr imaging study\nfurther unveils that the observed switching is mainly dominated by domain\nnucleation and domain wall motion, which might limit the potentiality of using\nthis type of multilayer stack design for nanoscale SOT-MRAM application.\nComparison of the experimental switching behavior with micromagnetic\nsimulations reveals that the deterministic switching in our devices cannot be\nexplained by the stray field contribution of the in-plane magnetized layer, and\nthe roughness-caused N\\'eel coupling effect might play a more important role in\nachieving the observed field-free deterministic switching.",
        "positive": "Magnetic entropy change of ErAl2 magnetocaloric wires fabricated by a\n  powder-in-tube method: We report the fabrication of ErAl2 magnetocaloric wires by a powder-in-tube\nmethod (PIT) and the evaluation of magnetic entropy change through\nmagnetization measurements. The magnetic entropy change of ErAl2 PIT wires\nexhibits similar behavior to the bulk counterpart, while its magnitude is\nreduced by the decrease in the volume fraction of ErAl2 due to the surrounding\nnon-magnetic sheaths. We find that another effect reduces the magnetic entropy\nchange of the ErAl2 PIT wires around the Curie temperature, and discuss its\npossible origin in terms of a correlation between magnetic properties of ErAl2\nand mechanical properties of sheath material."
    },
    {
        "anchor": "Infrared absorption and Raman scattering on coupled plasmon--phonon\n  modes in superlattices: We consider theoretically a superlattice formed by thin conducting layers\nseparated spatially between insulating layers. The dispersion of two coupled\nphonon-plasmon modes of the system is analyzed by using Maxwell's equations,\nwith the influence of retardation included. Both transmission for the finite\nplate as well as absorption for the semi-infinite superlattice in the infrared\nare calculated. Reflectance minima are determined by the longitudinal and\ntransverse phonon frequencies in the insulating layers and by the density-state\nsingularities of the coupled modes. We evaluate also the Raman cross section\nfrom the semi-infinite superlattice.",
        "positive": "Electric Field Tuned Dimensional Crossover in Ar-Irradiated SrTiO3: We present low temperature magnetoresistance measurements of Ar-irradiated\nSrTiO3 under an applied electrostatic field. The electric field, applied\nthrough a back gate bias, modulates both the mobility and sheet density, with a\ngreater effect on the former. For high mobilities, 3-dimensional orbital\nmagnetoresistance is observed. For low mobilities, negative magnetoresistance\nthat is consistent with the suppression of 2-dimensional weak-localization is\nobserved. The crossover from 3 to 2-dimensional transport arises from a\nmodulation in the carrier confinement, which is enhanced by the electric field\ndependent dielectric constant of SrTiO3. The implications of our results on the\ndevelopment of oxide electronic devices will be discussed."
    },
    {
        "anchor": "Characterization of the Surface of Moving solid 4He: Crystal grains of solid $^4$He can move in relation to each other even when\nembedded inside the solid. In this work, we characterize a macroscopic motion\nof solid hcp $^4$He composed of such grains. Motion is induced by applying an\nexternal torque to the solid contained inside an annular channel mounted on a\ntorsional oscillator. In order to characterize the surface of the moving solid,\nwe developed an in-situ flow detection method using a sensitive \"microphone\"\nembedded in the wall of the channel. Motion is detected by counting the\nvibrations induced by rows of He atoms moving past the microphone. Such\nvibrations were detected only at T=0.5K, our lowest temperature. At this\ntemperature, the measured dissipation associated with the solid He is zero\nwithin our accuracy. Our results indicate that the orientation of the surface\nof the moving solid is the (0001) basal plane of the hcp structure. At T=0.5 K,\nwe found that for speeds < 7 micrometer/sec, the solid flows without detectable\nfriction.",
        "positive": "The skyrmion switch: turning magnetic skyrmion bubbles on and off with\n  an electric field: Nanoscale magnetic skyrmions are considered as potential information carriers\nfor future spintronics memory and logic devices. Such applications will require\nthe control of their local creation and annihilation, which involves so far\nsolutions that are either energy consuming or difficult to integrate. Here we\ndemonstrate the control of skyrmion bubbles nucleation and annihilation using\nelectric field gating, an easily integrable and potentially energetically\nefficient solution. We present a detailed stability diagram of the skyrmion\nbubbles in a Pt/Co/oxide trilayer and show that their stability can be\ncontrolled via an applied electric field. An analytical bubble model, with the\nDzyaloshinskii-Moriya interaction imbedded in the domain wall energy, account\nfor the observed electrical skyrmion switching effect. This allows us to unveil\nthe origin of the electrical control of skyrmions stability and to show that\nboth magnetic dipolar interaction and the Dzyaloshinskii-Moriya interaction\nplay an important role in the skyrmion bubble stabilization."
    },
    {
        "anchor": "Can Inorganic Salts Tune Electronic Properties of Graphene?: Electronic properties of graphene quantum dots (GQDs) constitute a subject of\nintense scientific interest. Being smaller than 20 nm, GQDs contain confined\nexcitons in all dimensions simultaneously. GQDs feature a non-zero band gap and\nluminesce on excitation. Tuning their electronic structure is an attractive\ngoal with a technological promise. In this work, we apply density functional\ntheory to study an effect of neutral ionic clusters adsorbed on GQD surface. We\nconclude that both HOMO and LUMO of GQD are very sensitive to the presence of\nions and to their distance from the GQD surface. However, the alteration of the\nband gap itself is modest, as opposed to the case of free ions (recent\nreports). Our work fosters progress in modulating electronic properties of\nnanoscale carbonaceous materials.",
        "positive": "Ferroelectric Control of Magnetism and Transport in Oxide\n  Heterostructures: Magnetism and transport are two key functional ingredients in modern\nelectronic devices. In oxide heterostructures, ferroelectricity can provide a\nnew route to control these two properties via electrical operations, which is\nscientifically interesting and technologically important. In this Brief Review,\nwe will introduce recent progresses on this fast developing research field.\nSeveral subtopics will be covered. First, the ferroelectric polarization tuning\nof interfacial magnetism will be introduced, which includes the tuning of\nmagnetization, easy axis, magnetic phases, as well as exchange bias. Second,\nthe ferroelectric polarization tuning of transverse and tunneling transport\nwill be reviewed."
    },
    {
        "anchor": "Grain boundary segregation in steels: Towards engineering the design of\n  internal interfaces: Solute decoration at grain boundaries (GB) leads to a number of phenomenon\nsuch as changes in interface structure,mobility,cohesion etc.Recent\nexperimental investigations on interfacial segregation in steels are based on\nmicrostructural characterisation using two correlative methodologies,\nnamely,Transmission Electron Microscopy-Atom Probe Tomography (APT) and\nElectron Backscatter Diffraction-APT.Considering the growing interest in this\navenue,the present review is aimed at addressing the common adsorption\nisotherms used for quantifying interfacial segregation and providing an\noverview of the present state of experimental research in the area of GB\nsegregation in steels.The areas where an understanding of GB segregation may be\nutilised have also been highlighted with a focus on the experimental challenges\nassociated with understanding GB segregation in steels.",
        "positive": "Modelling and Simulation of Charging and Discharging Processes in\n  Nanocrystal Flash Memories During Program and Erase Operations: This work is focused on the understanding of charging and discharging\nprocesses in silicon nanocrystal flash memories during program and erase\noperations through time-dependent numerical simulations. Time dependent\nsimulations of the program and erase operations are based on a description of\nthe nanocrystal memory dynamics in terms of a master equation. The related\ntransition rates are computed with a one dimensional Poisson-Schroedinger\nsolver which allows the computation of the tunnelling currents and of\ngeneration and recombination rates between the outer reservoir and localized\nstates in the dielectric layer. Comparison between simulations and experiments\navailable in the literature provides useful insights of the storing mechanisms.\nIn particular, simulations allow us to rule out that electrons are stored in\nconfined states in the conduction band of silicon nanocrystals, whereas they\nsuggest that electrons are actually trapped in localized states in the silicon\ngap at an energy close to the silicon valence band edge, and located at the\ninterface between the nanocrystals and the surrounding silicon oxide."
    },
    {
        "anchor": "The effect of the misfit dislocation on the in-plane shear response of\n  the ferrite/cementite interface: Although the pearlitic steel is one of the most extensively studied\nmaterials, there are still questions unanswered about the interface in the\nlamellar structure. In particular, to deepen the understanding of the\nmechanical behavior of pearlitic steel with fine lamellar structure, it is\nessential to reveal the structure-property relationship of the\nferrite/cementite interface (FCI). In this study, we analyzed the in-plane\nshear deformation of the FCI using atomistic simulation combined with extended\natomically informed Frank-Bilby (xAIFB) method and disregistry analyses. In the\natomistic simulation, we applied in-plane shear stress along twelve different\ndirections to the ferrite/cementite bilayer for Isaichev (IS), Near Bagaryatsky\n(Near BA) and Near Pitsch-Petch (Near PP) orientation relationship (OR),\nrespectively. The simulation results reveal that IS and Near BA ORs show\ndislocation-mediated plasticity except two directions, while Near PP OR shows\nmode II (in-plane shear) fracture at the FCI along all directions. Based on the\nxAIFB and disregistry analysis results, we conclude that the in-plane shear\nbehavior of the FCI is governed by the magnitude of Burgers vector and\ncore-width of misfit dislocations.",
        "positive": "Ab initio constraints on silica melting to 500 GPa: The melting curve of pure silica (SiO$_2$) was determined using {\\it ab\ninitio} density functional theory together with the solid-liquid coexisting\napproach, thermodynamic integration and the Z method. The melting curves are\nconsistent with a smooth slow increase in a large region from 50 GPa (dT/dP\n$\\approx$ 15 K/GPa) to about 500 GPa (dT/dP $\\approx$ 5 K/GPa) without any\nabrupt changes at around 120 GPa and 300 GPa as seen in some recent\nexperimental and computational studies. The topography of the melting curve\nabove 50 GPa is consistent with a gradual change in the distribution of the Si\ncoordination numbers in the liquid state and the absence of large changes in\nthe density following solid-solid phase transitions. The pair distribution\nfunctions show that the structural correlation in the liquid is mainly\nshort-ranged and that the Si-O bond is stiff. The densification of the melt\nstructure with pressure above 50 GPa is therefore due to an increase in 7- and\n8-fold coordinated silicon."
    },
    {
        "anchor": "New generation of effective core potentials from correlated\n  calculations: 2nd row elements: Very recently, we have introduced correlation consistent effective core\npotentials (ccECPs) derived from many-body approaches with the main target\nbeing its use in explicitly correlated methods but also in mainstream\napproaches. The ccECPs are based on reproducing excitation energies for a\nsubset of valence states, i.e., achieving a near-isospectrality between the\noriginal and pseudo Hamiltonians. In addition, binding curves of dimer\nmolecules have been used for refinement and overall improvement of\ntransferability over a range of bond lengths. Here we apply similar ideas to\nthe second row elements and study several aspects of the constructions in order\nto find the optimal (or nearly-optimal) solutions within the chosen ECP forms\nwith $3s,3p$ valence space (Ne-core). New constructions exhibit accurate\nlow-lying atomic excitations and equilibrium molecular bonds (on average within\n$\\approx$ $0.03$ eV and $3$ m\\AA), however, the errors for Al and Si oxide\nmolecules at short bond lengths are notably larger for both ours and existing\nECPs. Assuming this limitation, our ccECPs show a systematic balance between\nthe criteria of atomic spectra accuracy and transferability for molecular\nbonds. In order to provide another option with much higher uniform accuracy, we\nalso construct He-core ECPs for the whole row with typical discrepancies of\n$\\approx$ 0.01 eV or smaller.",
        "positive": "Analogs of Rashba-Edelstein effect from density functional theory: Studies of structure-property relationships in spintronics are essential for\nthe design of materials that can fill specific roles in devices. For example,\nmaterials with low symmetry allow unconventional configurations of\ncharge-to-spin conversion which can be used to generate efficient spin-orbit\ntorques. Here, we explore the relationship between crystal symmetry and\ngeometry of the Rashba-Edelstein effect (REE) that causes spin accumulation in\nresponse to an applied electric current. Based on a symmetry analysis performed\nfor 230 crystallographic space groups, we identify classes of materials that\ncan host conventional or collinear REE. Although transverse spin accumulation\nis commonly associated with the so-called 'Rashba materials', we show that the\npresence of specific spin texture does not easily translate to the\nconfiguration of REE. More specifically, bulk crystals may simultaneously host\ndifferent types of spin-orbit fields, depending on the crystallographic point\ngroup and the symmetry of the specific $k$-vector, which, averaged over the\nBrillouin zone, determine the direction and magnitude of the induced spin\naccumulation. To explore the connection between crystal symmetry, spin texture,\nand the magnitude of REE, we perform first-principles calculations for\nrepresentative materials with different symmetries. We believe that our results\nwill be helpful for further computational and experimental studies, as well as\nthe design of spintronics devices."
    },
    {
        "anchor": "Benchtop Nonresonant X-ray Emission Spectroscopy: Coming Soon to\n  Laboratories and XAS Beamlines Near You?: Recently developed instrumentation at the University of Washington has\nallowed for nonresonant x-ray emission spectra (XES) to be measured in a\nlaboratory-setting with an inexpensive, easily operated system. We present a\ncritical evaluation of this equipment by means of K\\b{eta} and valence-level\nXES measurements for several Co compounds. We find peak count rates of ~5000/s\nfor concentrated samples and a robust relative energy scale with\nreproducibility of 25 meV or better. We furthermore find excellent agreement\nwith synchrotron measurements with only modest loss in energy resolution.\nInstruments such as ours, based on only conventional sources that are widely\nsold for elemental analysis by x-ray fluorescence, can fill an important role\nto diversify the research applications of XES both by their presence in\nnon-synchrotron laboratories and by their use in conjunction with XAFS\nbeamlines where the complementarity of XAFS and XES holds high scientific\npotential.",
        "positive": "Magnetism and electronic structure of YTiO$_3$ thin films: High-quality (001)-oriented (pseudo-cubic notation) ferromagnetic YTiO$_3$\nthin films were epitaxially synthesized in a layer-by-layer way by pulsed laser\ndeposition. Structural, magnetic and electronic properties were characterized\nby reflection-high-energy-electron-diffraction, X-ray diffraction, vibrating\nsample magnetometry, and element-resolved resonant soft X-ray absorption\nspectroscopy. To reveal ferromagnetism of the constituent titanium ions, X-ray\nmagnetic circular dichroism spectroscopy was carried out using four detection\nmodes probing complimentary spatial scale, which overcomes a challenge of\nprobing ferromagnetic titanium with pure Ti3+(3d$^1$). Our work provides a\npathway to distinguish between the roles of titanium and A-site magnetic\nrare-earth cations in determining the magnetism in rare-earth titanates thin\nfilms and heterostructures."
    },
    {
        "anchor": "Randomness-Induced Redistribution of Vibrational Frequencies in\n  Amorphous Solids: Much of the discussion in the literature of the low frequency part of the\ndensity of states of amorphous solids was dominated for years by comparing\nmeasured or simulated density of states to the classical Debye model. Since\nthis model is hardly appropriate for the materials at hand, this created some\namount of confusion regarding the existence and universality of the so- called\n``Boson Peak'' which results from such comparisons. We propose that one should\npay attention to the different roles played by different aspects of disorder,\nthe first being disorder in the interaction strengths, the second positional\ndisorder, and the third coordination disorder. These have different effects on\nthe low-frequency part of the density of states. We examine the density of\nstates of a number of tractable models in one and two dimensions, and reach a\nclearer picture of the softening and redistribution of frequencies in such\nmaterials. We discuss the effects of disorder on the elastic moduli and the\nrelation of the latter to frequency softening, reaching the final conclusion\nthat the Boson peak is not universal at all.",
        "positive": "Enhanced spin pumping efficiency in antiferromagnetic IrMn thin films\n  around the magnetic phase transition: We report measurement of a spin pumping effect due to fluctuations of the\nmagnetic order of IrMn thin films. A precessing NiFe ferromagnet injected spins\ninto IrMn spin sinks, and enhanced damping was observed around the IrMn\nmagnetic phase transition. Our data was compared to a recently developed theory\nand converted into interfacial spin mixing conductance enhancements. By\nspotting the spin pumping peak, the thickness dependence of the IrMn critical\ntemperature could be determined and the characteristic length for the spin-spin\ninteractions was deduced."
    },
    {
        "anchor": "Transport properties of two-dimensional electron systems on silicon\n  (111) surfaces: We theoretically study transport properties of a two-dimensional electron\nsystem on a hydrogen-passivated Si(111) surface in the field-effect-transistor\n(FET) configuration. We calculate the density and temperature dependent\nmobility and resistivity for the recently fabricated Si(111)-vacuum FET by\nusing a semiclassical Boltzmann theory including screened charged impurity\nscattering. We find reasonable agreement with the corresponding experimental\ntransport properties, indicating that the screened disorder potential from\nrandom charged impurities is the main scattering mechanism. We also find that\nthe theoretical results with the valley degeneracy $g_v=2$ give much better\nagreement with experiment than the $g_v=6$ situation indicating that the usual\nbulk six-valley degeneracy of Si is lifted in this system.",
        "positive": "Electron spin relaxation in carbon nanotubes: The long standing problem of inexplicably short spin relaxation in carbon\nnanotubes (CNTs) is examined. The curvature-mediated spin-orbital interaction\nis shown to induce fluctuating electron spin precession causing efficient\nrelaxation in a manner analogous to the Dyakonov-Perel mechanism. Our\ncalculation estimates longitudinal (spin-flip) and transversal (decoherence)\nrelaxation times as short as 150 ps and 110 ps at room temperature,\nrespectively, along with a pronounced anisotropic dependence. Interference of\nelectrons originating from different valleys can lead to even faster dephasing.\nThe results can help clarify the measured data, resolving discrepancies in the\nliterature."
    },
    {
        "anchor": "Electron-phonon interaction and surface effects on the optoelectronic\n  properties of diamondoids: A comparative study: Unusual optoelectronic properties of diamondoids produce some discrepancies\nbetween experiments and the outstanding many-body calculation outputs.\nTherefore, many theoretical efforts are attracted to resolve these\ninconsistencies. Here first, by combining time-dependent density functional\ntheory (TD-DFT) and Franck-Condon (FC) approximation, the effect of\nelectron-phonon (e-ph) interaction on the optical gap (OG) of the smallest\ndiamondoids and one of its derivatives is studied. Then, the surface effects on\nthe e-ph coupling and the optical properties of these structures in a\ncomparative manner are considered. We show that the collective motion of\ncarbons modifies the previous OG of adamantane predicted by TD-DFT technique.\nThe introduction of this effect can also fully explain the overestimated gap\npredicted by the diffusion quantum Monte-Carlo (DMC) method. In addition, we\nshow that the chemistry of the surface is another noticeable effect that can\ninfluence the OG renormalization and the spectral lineshape of the system.",
        "positive": "An effective anisotropic visco-plastic model dedicated to high contrast\n  ductile laminated microstructures: Application to lath martensite\n  substructure: In particular types of layer- or lamellar-like microstructures such as\npearlite and lath martensite, plastic slip occurs favorably in directions\nparallel to inter-lamellar boundaries. This may be due to the interplay between\nmorphology and crystallographic orientation or, more generally, due to\nconstraints imposed on the plastic slip due to the lamellar microstructural\ngeometry. This paper proposes a micromechanics based, computationally\nefficient, scale independent model for particular type of lamellar\nmicrostructures containing softer lamellae, which are sufficiently thin to be\nconsidered as discrete slip planes embedded in a matrix representing the harder\nlamellae. Accordingly, the model is constructed as an isotropic visco-plastic\nmodel which is enriched with an additional orientation-dependent planar plastic\ndeformation mechanism. This additional mode is activated when the applied load,\nprojected on the direction of the soft films, induces a significant amount of\nshear stress. Otherwise, the plastic deformation is governed solely by the\nisotropic part of the model. The response of the proposed model is assessed via\na comparison to direct numerical simulations (DNS) of an infinite periodic\ntwo-phase laminate. It is shown that the yielding behavior of the model follows\nthe same behavior as the reference model. It is observed that the proposed\nmodel is highly anisotropic, and the degree of anisotropy depends on the\ncontrast between the slip resistance (or yield stress) of the planar mode\nversus that of the isotropic part. The formulation is then applied to model the\nsubstructure of lath martensite with inter-layer thin austenite films. It is\nexploited in a mesoscale simulation of a dual-phase (DP) steel\nmicrostructure.The results are compared with those of a standard isotropic\nmodel and a full crystal plasticity model."
    },
    {
        "anchor": "Weyl semimetal phase in non-centrosymmetric transition metal\n  monophosphides: Based on first principle calculations, we show that a family of nonmagnetic\nmaterials including TaAs, TaP, NbAs and NbP are Weyl semimetal (WSM) without\ninversion center. We find twelve pairs of Weyl points in the whole Brillouin\nzone (BZ) for each of them. In the absence of spin-orbit coupling (SOC), band\ninversions in mirror invariant planes lead to gapless nodal rings in the\nenergy-momentum dispersion. The strong SOC in these materials then opens full\ngaps in the mirror planes, generating nonzero mirror Chern numbers and Weyl\npoints off the mirror planes. The resulting surface state Fermi arc structures\non both (001) and (100) surfaces are also obtained and show interesting shapes,\npointing to fascinating playgrounds for future experimental studies.",
        "positive": "Novel Two-dimensional Carbon Allotrope with Strong Electronic Anisotropy: Two novel two-dimensional carbon allotropes comprised of octagons and\npentagons are proposed based on the first-principles calculations. The two\ncarbon allotropes, named OPG-L and OPG-Z, are found to have distinct\nproperties. OPG-L is metallic, while OPG-Z is a gapless semimetal. Remarkably,\nOPG-Z exhibits pronounced electronic anisotropy with highly anisotropic Dirac\npoints at the Fermi level. A tight-binding model is suggested to describe the\nlow-energy quasiparticles, which clarifies the origin of the anisotropic Dirac\npoints. Such an anisotropic electronic characteristic of OPG-Z is expected to\nhave wide implications in nano-electronics."
    },
    {
        "anchor": "Steric engineering of point defects in lead halide perovskites: Due to their high photovoltaic efficiency and low-cost synthesis, lead halide\nperovskites have attracted wide interest for application in new solar cell\ntechnologies. The most stable and efficient ABX$_3$ perovskite solar cells\nemploy mixed A-site cations, however the impact of cation mixing on carrier\ntrapping and recombination -- key processes that limit photovoltaic performance\n-- is not fully understood. Here we analyse non-radiative carrier trapping in\nthe mixed A-cation hybrid halide perovskite MA$_{1-x}$Cs$_x$PbI$_3$. By using\nrigorous first-principles simulations we show that cation mixing leads to a\nhole trapping rate at the iodine interstitial that is eight orders of magnitude\ngreater than in the single cation system. We demonstrate that the same defect\nin the same material can display a wide variety of defect activity -- from\nelectrically inactive to recombination centre -- and, in doing so, resolve\nconflicting reports in the literature. Finally, we propose a new mechanism in\nwhich steric effects can be used to determine the rate of carrier trapping;\nthis is achieved by controlling the phase and dynamical response of the lattice\nthrough the A-site composition. Our findings elucidate crucial links between\nchemical composition, defect activity and optoelectronic performance, and\nsuggest a general approach that can help to rationalise the development of new\ncrystalline materials with target defect properties.",
        "positive": "Temperature-dependent Raman scattering of DyScO3 and GdScO3 single\n  crystals: We report a temperature-dependent Raman scattering investigation of DyScO3\nand GdScO3 single crystals from room temperature up to 1200 {\\deg}C. With\nincreasing temperature, all modes decrease monotonously in wavenumber without\nanomaly, which attests the absence of a structural phase transition. The high\ntemperature spectral signature and extrapolation of band positions to higher\ntemperatures suggest a decreasing orthorhombic distortion towards the ideal\ncubic structure. Our study indicates that this orthorhombic-to-cubic phase\ntransition is close to or higher than the melting point of both rare-earth\nscandates (\\approx 2100 {\\deg}C), which might exclude the possibility of the\nexperimental observation of such a phase transition before melting. The\ntemperature-dependent shift of Raman phonons is also discussed in the context\nof thermal expansion."
    },
    {
        "anchor": "Evolution of interlayer and intralayer magnetism in three atomically\n  thin chromium trihalides: We conduct a comprehensive study of three different magnetic semiconductors,\nCrI$_3$, CrBr$_3$, and CrCl$_3$, by incorporating both few- and bi-layer\nsamples in van der Waals tunnel junctions. We find that the interlayer magnetic\nordering, exchange gap, magnetic anisotropy, as well as magnon excitations\nevolve systematically with changing halogen atom. By fitting to a spin wave\ntheory that accounts for nearest neighbor exchange interactions, we are able to\nfurther determine a simple spin Hamiltonian describing all three systems. These\nresults extend the 2D magnetism platform to Ising, Heisenberg, and XY spin\nclasses in a single material family. Using magneto-optical measurements, we\nadditionally demonstrate that ferromagnetism can be stabilized down to\nmonolayer in more isotropic CrBr$_3$, with transition temperature still close\nto that of the bulk.",
        "positive": "The role of charge traps in inducing hysteresis: capacitance - voltage\n  measurements on top gated bilayer graphene: Understanding the origin of hysteresis in the channel resistance from top\ngated graphene transistors is important for transistor applications.\nCapacitance - voltage measurements across the gate oxide on top gated bilayer\ngraphene show hysteresis with a charging and discharging time constant of ~100\n{\\mu}s. However, the measured capacitance across the graphene channel does not\nshow any hysteresis, but shows an abrupt jump at a high channel voltage due to\nthe emergence of an order, indicating that the origin of hysteresis between\ngate and source is due to charge traps present in the gate oxide and graphene\ninterface."
    },
    {
        "anchor": "Coherent Single Charge Transport in Molecular-Scale Silicon Nanowire\n  Transistors: We report low-temperature electrical transport studies of molecule-scale\nsilicon nanowires. Individual nanowires exhibit well-defined Coulomb blockade\noscillations characteristic of charge addition to a single nanostructure with\nlength scales up to at least 400 nm. Further studies demonstrate coherent\ncharge transport through discrete single particle quantum levels extending the\nwhole device, and show that the ground state spin configuration follows the\nLieb-Mattis theorem. In addition, depletion of the nanowires suggests that\nphase coherent single-dot characteristics are accessible in a regime where\ncorrelations are strong.",
        "positive": "Berry Phase and Topological Effects of Phonons: Phonons as collective excitations of lattice vibrations are the main heat\ncarriers in solids. Tremendous effort has been devoted to investigate phonons\nand related properties, giving rise to an intriguing field of phononics, which\nis of great importance to many practical applications, including heat\ndissipation, thermal barrier coating, thermoelectrics and thermal control\ndevices. Meanwhile, the research of topology-related physics, awarded the 2016\nNobel Prize in Physics, has led to discoveries of various exotic quantum states\nof matter, including the quantum (anomalous/spin) Hall [Q(A/S)H] effects,\ntopological insulators/semimetals and topological superconductors. An emerging\nresearch field is to bring topological concepts for a new paradigm\nphononics---\"topological phononics\". In this Perspective, we will briefly\nintroduce this emerging field and discuss the use of novel quantum degrees of\nfreedom like the Berry phase and topology for manipulating phonons in\nunprecedentedly new ways."
    },
    {
        "anchor": "Graphene decoupling through oxygen intercalation on Gr/Co and Gr/Co/Ir\n  interfaces: We perform a density functional theory study of the effects of oxygen\nadsorption on the structural and electronic properties of Gr/Co(0001) and\nGr/Co/Ir(111) interfaces. In both interfaces, the graphene-Co distance\nincreases with increasing O concentration. The oxygen intercalation effectively\ndecreases the electronic interaction, preventing the hybridization of graphene\nstates with Co $d$-orbitals, hence (partly) restoring the typical Dirac cone of\npristine graphene. In the case of graphene/Co 1ML/Ir(111), which presents a\nmoir\\'e pattern, the interplay between the O distribution and the continuous\nchange of the graphene-Co registry can be used to tune graphene corrugation and\nelectronic properties. The computed electronic properties are in very good\nagreement with previously reported angle resolved photoemission spectroscopy\nand photoemission electron microscopy measurements for Gr/Co(0001).",
        "positive": "Necessary and sufficient condition for a disorder-broadened transition\n  to be identified as 1st order: Disorder-broadened 1st order transitions may not carry the experimental\nsignature of a latent heat. We discuss what experimental observation can\nprovide a necessary and sufficient condition for characterizing this phase\ntransition as 1st order."
    },
    {
        "anchor": "Interfacial structure in organic optoelectronics: The interfacial structure plays a critical role in modern optoelectronics.\nCurrently multilayer electrodes are used to optimize the injection and lifetime\nproperties. The choice of interlayer is not universal, with different effects\nfor the same material with different capping metals. Using a novel in-situ\ncharacterization method with X-ray photoelectron spectroscopy, the\norganic/inorganic interface in OLEDs was examined for two common cathode metals\nwith a LiF interlayer. The impact of the interfacial layer on the performance\nof devices can be attributed to the bulk lattice matching of the interfacial\nlayer and of the by-products of interfacial oxidation, and the metallic\ncathode.",
        "positive": "A micromechanical analysis of intergranular stress corrosion cracking of\n  an irradiated austenitic stainless steel: Irradiation Assisted Stress Corrosion Cracking (IASCC) is a material\ndegradation phenomenon affecting austenitic stainless steels used in nuclear\nPressurized Water Reactors (PWR), leading to the initiation and propagation of\nintergranular cracks. Such phenomenon belongs to the broader class of\nInterGranular Stress Corrosion Cracking (IGSCC). A micromechanical analysis of\nIGSCC of an irradiated austenitic stainless steel is performed in this study to\nassess local cracking conditions. A 304L proton irradiated sample tested in PWR\nenvironment and showing intergranular cracking is investigated. Serial\nsectioning, Electron BackScatter Diffraction (EBSD) and a two-step misalignment\nprocedure are performed to reconstruct the 3D microstructure over an extended\nvolume, to assess statistically cracking criteria. A methodology is also\ndeveloped to compute Grain Boundary (GB) normal orientations based on the EBSD\nmeasurements. The statistical analysis shows that cracking occurs\npreferentially for GB normals aligned with the mechanical loading axis, but\nalso for low values of the Luster-Morris slip transmission parameter.\nMicromechanical simulations based on the reconstructed 3D microstructure,\nFFT-based solver and crystal plasticity constitutive equations modified to\naccount for slip transmission at grain boundaries are finally performed. These\nsimulations rationalize the correlation obtained experimentally into a single\nstress-based criterion. The actual strengths and weaknesses of such\nmicromechanical approach are discussed."
    },
    {
        "anchor": "Thin films of metallic carbon nanotubes and their optical spectra: We show that separating metallic from semiconducting carbon nanotubes by\ndielectrophoresis is developing towards a bulk separation method, which allows\nfor the first time to produce thin films of only metallic single-walled carbon\nnanotubes and to measure their optical absorption spectra. The data proofs that\nthe selectivity of the separation scheme is independent from the nanotube\ndiameter.",
        "positive": "Piezoelectric strain induced variation of the magnetic anisotropy in a\n  high Curie temperature (Ga,Mn)As sample: We show that effective electrical control of the magnetic properties in the\nferromagnetic semiconductor (Ga,Mn)As is possible using the strain induced by a\npiezoelectric actuator even in the limit of high doping levels and high Curie\ntemperatures, where direct electric gating is not possible. We demonstrate very\nlarge and reversible rotations of the magnetic easy axis. We compare the\nresults obtained from magneto-transport and SQUID magnetometry measurements,\nextracting the dependence of the piezo-induced uniaxial magnetic anisotropy\nconstant upon strain in both cases and detailing the limitations encountered in\nthe latter approach."
    },
    {
        "anchor": "Gate Stack Dielectric Degradation of Rare-Earth Oxides Grown on High\n  Mobility Ge Substrates: We report on the dielectric degradation of Rare-Earth Oxides (REOs), when\nused as interfacial buffer layers together with HfO2 high-k films (REOs/HfO2)\non high mobility Ge substrates. Metal-Oxide-Semiconductor (MOS) devices with\nthese stacks,show dissimilar charge trapping phenomena under varying levels of\nConstant- Voltage-Stress (CVS) conditions, which also influences the measured\ndensities of the interface (Nit) and border (NBT) traps. In the present study\nwe also report on C-Vg hysteresis curves related to Nit and NBT. We also\npropose a new model based on Maxwell-Wagner instabilities mechanism that\nexplains the dielectric degradations (current decay transient behavior) of the\ngate stack devices grown on high mobility substrates under CVS bias from low to\nhigher fields, and which is unlike to those used for other MOS devices.\nFinally, the time dependent degradation of the corresponding devices revealed\nan initial current decay due to relaxation, followed by charge trapping and\ngeneration of stress-induced leakage which eventually lead to hard breakdown\nafter long CVS stressing.",
        "positive": "Voltage and temperature dependencies of conductivity in gated graphene: The resistivity of gated graphene is studied taking into account electron and\nhole scattering by short- and long-range structural imperfections the\ncharacteristics of disorder were taken from the scanning tunneling microscopy\ndata and by acoustic phonons. The calculations are based on the quasiclassical\nkinetic equation with the normalization condition fixed by surface charge. The\ngate-voltage and temperature effects on the resistance peak, which is centered\nat the point of intrinsic conductivity, are found to be in agreement with the\ntransport measurements."
    },
    {
        "anchor": "Burgers space versus real space in the nonlinear theory of dislocations: Some double space tensorial quantities in the nonlinear theory of\ndislocations are considered. Their real space counterparts are introduced.",
        "positive": "From the Magnetization Profile to the Stray Field of Bistable Wires: We present new analytical calculations of the spatial dependence of the stray\nfield of a bistable magnetic wire from the magnetization profile of the wire.\nContributions from the outer shell and from the wire ends are neglected. The\nresults qualitatively agree with experimental data, taken from literature."
    },
    {
        "anchor": "Giant Flexoelectricity in Bent Silicon Thinfilms: We reveal that strong flexoelectric effect of solids can be induced due to\nthe signfi?cant charge migration along the strain gradient direction, which\nrepresents a new understanding of the origin of flexoelectricity. Beyond the\nlinear response theory, we illustrate such charge migration that is driven by\nan electric field effect in bent silicon thinfilms. Due to such charge\nmigration, the variation of atomic charge no longer represents a linear\nresponse to strain gradient and the resulting giant flexoelectric coeffcients\nbeing size dependent cannot be treated as a bulk property. The obtained\nflexoelectric coefficients compare well with the typical experimental values as\nreported in various ceramics. Our results shed light on elucidating the\ndiscrepancy between theory and experiment,and pave a new way to discover\nexcellent flexoelectric performance in conventional materials.",
        "positive": "Spin Seebeck effect in the layered ferromagnetic insulators CrSiTe$_3$\n  and CrGeTe$_3$: We have studied the longitudinal spin Seebeck effect (LSSE) in the layered\nferromagnetic insulators CrSiTe$_3$ and CrGeTe$_3$ covered by Pt films in the\nmeasurement configuration where spin current traverses the ferromagnetic Cr\nlayers. The LSSE response is clearly observed in the ferromagnetic phase and,\nin contrast to a standard LSSE magnet Y$_3$Fe$_5$O$_{12}$, persists above the\ncritical temperatures in both CrSiTe$_3$/Pt and CrGeTe$_3$/Pt samples. With the\nhelp of a numerical calculation, we attribute the LSSE signals observed in the\nparamagnetic regime to exchange-dominated interlayer transport of in-plane\nparamagnetic moments reinforced by short-range ferromagnetic correlations and\nstrong Zeeman effects."
    },
    {
        "anchor": "Transferability of crystal-field parameters for rare-earth ions in\n  Y$_2$SiO$_5$ tested by Zeeman spectroscopy: Zeeman spectroscopy is used to demonstrate that phenomenological\ncrystal-field parameters determined for the two $C_1$ point-group sites in\nEr$^{3+}$:Y$_2$SiO$_5$ may be transferred to other ions. The two\ncrystallographic six- and seven-coordinate substitutional sites may be\ndistinguished by comparing the spectra with crystal-field calculations.",
        "positive": "Manipulating thermal fields with inhomogeneous heat spreaders: We design a class of spatially inhomogeneous heat spreaders in the context of\nsteady-state thermal conduction leading to spatially uniform thermal fields\nacross a large convective surface. Each spreader has a funnel-shaped design,\neither in the form of a trapezoidal prism or truncated cone, and is forced by a\nthermal source at its base. We employ transformation-based techniques, commonly\nused to study metamaterials, to determine the require thermal conductivity for\nthe spreaders. The obtained materials, although strongly anisotropic and\ninhomogeneous, can be accurately approximated by assembling isotropic,\nhomogeneous layers, rendering them realisable. An alternative approach is then\nconsidered for the conical and trapezoidal spreaders by dividing them into two\nor three isotropic, homogeneous components respectively. We refer to these\nsimple configurations as neutral layers. All designs are validated numerically\nboth with and without the effects of thermal contact resistance between\ninterfaces. Such novel designs pave the way for future materials that can\nmanipulate and control the flow of heat, helping to solve traditional heat\ntransfer problems such as controlling the temperature of an object and energy\nharvesting."
    },
    {
        "anchor": "Negative Longitudinal Magneto-Thermoelectric Power in a Semiconductor\n  Parabolic Quantum Well: We present a theoretical study of the electronic thermoelectric power of a\nsemiconductor parabolic quantum well in a magnetic field. The case of a\nlongitudinal magnetic field, with respect to the temperature gradient, has been\nconsidered. The calculations were carried out taking into account\nspin-splitting of the dimensionally quantized electronic energy levels. It has\nbeen shown that in the region of strong confinement the thermoelectric power\ndecreases with increasing magnetic field, which is related to the downward\nshift of the lower Zeeman-split spin subband.",
        "positive": "Tunable electronic properties and band alignments of MoSi$_2$N$_4$/GaN\n  and MoSi$_2$N$_4$/ZnO van der Waals heterostructures: Van de Waals heterostructures (VDWH) is an emerging strategy to engineer the\nelectronic properties of two-dimensional (2D) material systems. Motivated by\nthe recent discovery of MoSi$_2$N$_4$ - a synthetic septuple-layered 2D\nsemiconductor with exceptional mechanical and electronic properties, we\ninvestigate the synergy of \\ce{MoSi2N4} with wide band gap (WBG) 2D monolayers\nof GaN and ZnO using first-principle calculations. We find that\nMoSi$_2$N$_4$/GaN is a direct band gap Type-I VDWH while MoSi$_2$N$_4$/ZnO is\nan indirect band gap Type-II VDWH. Intriguingly, by applying an electric field\nor mechanical strain along the out-of-plane direction, the band structures of\nMoSi$_2$N$_4$/GaN and MoSi$_2$N$_4$/ZnO can be substantially modified,\nexhibiting rich transitional behaviors, such as the Type-I-to-Type-II band\nalignment and the direct-to-indirect band gap transitions. These findings\nreveal the potentials of MoSi$_2$N$_4$-based WBG VDWH as a tunable hybrid\nmaterials with enormous design flexibility in ultracompact optoelectronic\napplications."
    },
    {
        "anchor": "Magnetic Yoking and Tunable Interactions in FePt-Based Hard/Soft\n  Bilayers: Assessing and controlling magnetic interactions in magnetic nanostructures\nare critical to nanomagnetic and spintronic explorations, such as magnetic\nrecording media, permanent magnets, magnetic memory and logic devices, etc.\nHere we demonstrate an extremely sensitive magnetic yoking effect and tunable\ninteractions in FePt based hard/soft bilayers mediated by the soft layer. Below\nthe exchange length, a thin soft layer strongly exchange couples to the\nperpendicular moments of the hard layer; above the exchange length, just a few\nnanometers thicker, the soft layer moments turn in-plane and act to yoke the\ndipolar fields from the adjacent hard layer perpendicular domains. The\nevolution from exchange to dipolar-dominated interactions is experimentally\ncaptured by first-order reversal curves, the delta-M method, and polarized\nneutron reflectometry, and confirmed by micromagnetic simulations. These\nfindings demonstrate an effective yoking approach to design and control\nmagnetic interactions in wide varieties of magnetic nanostructures and devices.",
        "positive": "Angle-resolved photoemission spectroscopy study of the charge density\n  wave order in layered semiconductor EuTe4: Layered tellurides have been extensively studied as a platform for\ninvestigating the Fermi surface (FS) nesting-driven charge density wave (CDW)\nstates. EuTe4, one of quasi-two-dimensional (quasi-2D) binary rare-earth\ntetratellurides CDW compounds, with unconventional hysteretic transition, is\ncurrently receiving much attention. Here, the CDW modulation vector, momentum\nand temperature dependence of CDW gaps in EuTe4 are investigated using\nangle-resolved photoemission spectroscopy. Our results reveal that (i) a FS\nnesting vector q ~ 0.67 b* drives the formation of CDW state, (ii) a large\nanisotropic CDW gap is fully open in the whole FS, and maintains a considerable\nsize even at 300 K, leading to appearance of semiconductor properties, (iii) an\nabnormal non-monotonic increase of CDW gap in magnitude as a function of\ntemperature, (iv) an extra, larger gap opens at a higher binding energy due to\nthe interaction between the different orbits of the main bands."
    },
    {
        "anchor": "Electrically and magnetically induced optical rotation in Pb5Ge3O11:Cr\n  crystals at the phase transition. 2. Faraday effect in pure and Cr-doped lead\n  germanate in the presence of electric field and spontaneous polarization: This work presents the results for the Faraday rotation in pure and Cr-doped\nlead germanate crystals studied in the course of proper ferroelectric phase\ntransition. We show that the increment of the Faraday rotation appearing at the\nphase transition is caused by a combined magneto-electrooptic effect induced by\nspontaneous polarization. It is proportional to the square of spontaneous\npolarization. The phenomenon revealed by us corresponds to combined effects of\ncrystal optics, which appear due to common action of different fields.",
        "positive": "Observation of Open-Orbit Fermi Surface Topology in Extremely Large\n  Magnetoresistance Semimetal MoAs$_2$: While recent advances in band theory and sample growth have expanded the\nseries of extremely large magnetoresistance (XMR) semimetals in transition\nmetal dipnictides $TmPn_2$ ($Tm$ = Ta, Nb; $Pn$ = P, As, Sb), the experimental\nstudy on their electronic structure and the origin of XMR is still absent.\nHere, using angle-resolved photoemission spectroscopy combined with\nfirst-principles calculations and magnetotransport measurements, we performed a\ncomprehensive investigation on MoAs$_2$, which is isostructural to the $TmPn_2$\nfamily and also exhibits quadratic XMR. We resolve a clear band structure well\nagreeing with the predictions. Intriguingly, the unambiguously observed Fermi\nsurfaces (FSs) are dominated by an open-orbit topology extending along both the\n[100] and [001] directions in the three-dimensional Brillouin zone. We further\nreveal the trivial topological nature of MoAs$_2$ by bulk parity analysis.\nBased on these results, we examine the proposed XMR mechanisms in other\nsemimetals, and conclusively ascribe the origin of quadratic XMR in MoAs$_2$ to\nthe carriers motion on the FSs with dominant open-orbit topology, innovating in\nthe understanding of quadratic XMR in semimetals."
    },
    {
        "anchor": "Is High-density Amorphous Ice Simply a 'Derailed' State along the Ice I\n  to Ice IV Pathway?: The structural nature of high-density amorphous ice (HDA), which forms\nthrough low-temperature pressure-induced amorphization of the 'ordinary' ice I,\nis heavily debated. Clarifying this question is not only important for\nunderstanding the complex condensed states of H$_2$O but also in the wider\ncontext of pressure-induced amorphization processes, which are encountered\nacross the entire materials spectrum. We first show that ammonium fluoride\n(NH$_4$F), which has a similar hydrogen-bonded network to ice I, also undergoes\na pressure collapse upon compression at 77 K. However, the product material is\nnot amorphous but NH$_4$F II, a high-pressure phase isostructural with ice IV.\nThis collapse can be rationalized in terms of a highly effective mechanism. In\nthe case of ice I, the orientational disorder of the water molecules leads to a\ndeviation from this mechanism and we therefore classify HDA as a 'derailed'\nstate along the ice I to ice IV pathway.",
        "positive": "Studies of Effects of Current on Exchange-Bias: A Brief Review: MacDonald and co-workers recently predicted that high current densities could\naffect the magnetic order of antiferromagnetic (AFM) multilayers, in ways\nsimilar to those that occur in ferromagnetic (F) multilayers, and that changes\nin AFM magnetic order can produce an antiferromagnetic Giant Magnetoresistance\n(AGMR). Four groups have now studied current-driven effects on exchange bias at\nF/AFM interfaces. In this paper, we first briefly review the main predictions\nby MacDonald and co-workers, and then the results of experiments on exchange\nbias that these predictions stimulated."
    },
    {
        "anchor": "Expansion algorithm for the density matrix: A purification algorithm for expanding the single-particle density matrix in\nterms of the Hamiltonian operator is proposed. The scheme works with a\npredefined occupation and requires less than half the number of matrix-matrix\nmultiplications compared to existing methods at low (<10%) and high (>90%)\noccupancy. The expansion can be used with a fixed chemical potential in which\ncase it is an asymmetric generalization of and a substantial improvement over\ngrand canonical McWeeny purification. It is shown that the computational\ncomplexity, measured as number of matrix multiplications, essentially is\nindependent of system size even for metallic materials with a vanishing band\ngap.",
        "positive": "Optical transitions in quantum ring complexes: Making use of a droplet-epitaxial technique, we realize nanometer-sized\nquantum ring complexes, consisting of a well-defined inner ring and an outer\nring. Electronic structure inherent in the unique quantum system is analyzed\nusing a micro-photoluminescence technique. One advantage of our growth method\nis that it presents the possibility of varying the ring geometry. Two samples\nare prepared and studied: a single-wall ring and a concentric double-ring. For\nboth samples, highly efficient photoluminescence emitted from a single quantum\nstructure is detected. The spectra show discrete resonance lines, which reflect\nthe quantized nature of the ring-type electronic states. In the concentric\ndouble--ring, the carrier confinement in the inner ring and that in the outer\nring are identified distinctly as split lines. The observed spectra are\ninterpreted on the basis of single electron effective mass calculations."
    },
    {
        "anchor": "Interplay of the exciton and electron-hole plasma recombination on the\n  photoluminescence dynamics in bulk GaAs: We present a systematic study of the exciton/electron-hole plasma\nphotoluminescence dynamics in bulk GaAs for various lattice temperatures and\nexcitation densities. The competition between the exciton and electron-hole\npair recombination dominates the onset of the luminescence. We show that the\nmetal-to-insulator transition, induced by temperature and/or excitation\ndensity, can be directly monitored by the carrier dynamics and the\ntime-resolved spectral characteristics of the light emission. The dependence on\ncarrier density of the photoluminescence rise time is strongly modified around\na lattice temperature of 49 K, corresponding to the exciton binding energy (4.2\nmeV). In a similar way, the rise-time dependence on lattice temperature\nundergoes a relatively abrupt change at an excitation density of 120-180x10^15\ncm^-3, which is about five times greater than the calculated Mott density in\nGaAs taking into account many body corrections.",
        "positive": "Phase Diagrams and Domain Splitting in Thin Ferroelectric Films with\n  Incommensurate Phases: We studied the phase diagram of thin ferroelectric films with incommensurate\nphases and semiconductor properties within the framework of\nLandau-Ginzburg-Devonshire theory. We performed both analytical calculations\nand phase-field modelling of the temperature and thickness dependencies of the\nperiod of incommensurate 180 degree domain structures appeared in thin films\ncovered with perfect electrodes. It is found that the transition temperature\nfrom the paraelectric into the incommensurate phase as well as the period of\nincommensurate domain structure strongly depend on film thickness, and surface\nand gradient energy contributions. The results may provide insight on the\ntemperature dependence of domain structures in nanosized ferroics with inherent\nincommensurate phases."
    },
    {
        "anchor": "Low temperature shape relaxation of 2-d islands by edge diffusion: We present a precise microscopic description of the limiting step for low\ntemperature shape relaxation of two dimensional islands in which activated\ndiffusion of particles along the boundary is the only mechanism of transport\nallowed. In particular, we are able to explain why the system is driven\nirreversibly towards equilibrium. Based on this description, we present a\nscheme for calculating the duration of the limiting step at each stage of the\nrelaxation process. Finally, we calculate numerically the total relaxation time\nas predicted by our results and compare it with simulations of the relaxation\nprocess.",
        "positive": "Unexpected Spontaneously Dynamic Oxygen Migration on Carbon Nanotubes: Using the density functional theory calculations, we show that the oxygen\nfunctional groups exhibit unexpected spontaneously dynamic behaviors on the\ninterior surface of single-walled carbon nanotubes (SWCNT). Two types of\ndynamic oxygen migrations - hydroxyl and epoxy migrations - are achieved by the\nbreaking/reforming of C-O bond reaction and the proton transfer reaction. It is\ndemonstrated that the spontaneously dynamic characteristic is attributed to the\nsharply reduced energy barrier less than or comparable to thermal fluctuations.\nWe also observe a stable intermediate state with a dangling C-O bond, which\npermits the successive migration of oxygen functional groups. However, on the\nexterior surface of SWCNT, the oxygen groups are difficult to migrate\nspontaneously due to the relatively high energy barriers, and the dangling C-O\nbond prefers to transform into the more stable epoxy configuration. The\nspontaneous oxygen migration is further confirmed by the long-distance oxygen\nmigration, which comprises three hydroxyl migration reactions and one C-O bond\nreaction. Our work provides a new understanding of the behavior of oxygen\nfunctional groups on interfaces and gives a potential route to design new\ncarbon-based dynamic materials."
    },
    {
        "anchor": "Magnetoresistance and surface roughness study of electrodeposited\n  Ni50Co50/Cu multilayers: Room-temperature transport properties (the zero-field resistivity, \\rho 0,\nand the GMR) were studied for ED Ni50Co50/Cu multilayers as a function of the\nindividual layer thicknesses and total multilayer thickness. The Cu deposition\npotential was optimized in order to obtain the preset layer thicknesses. The\nsurface roughness development was studied by AFM, which revealed an exponential\nroughening with total thickness. The Cu layer thickness strongly influenced the\nroughness evolution. As expected, \\rho 0 decreased with increasing Cu layer\nthickness whereas it increased strongly for large total multilayer thicknesses\nthat could be ascribed to the observed deposit roughening. All multilayers with\nCu layer thicknesses above about 1.5 nm exhibited a GMR behavior with a maximum\nGMR of about 5 %. The GMR decreased for total multilayer thicknesses above\nabout 300 nm due to the strong increase of \\rho 0, the latter caused by the\nenhanced roughness. The GMR data indicated the appearance of a current at angle\nto plane type scattering due to the layer undulations. The thickness evolution\nof the MR data was analyzed in detail after separating the ferromagnetic and\nsuperparamagnetic GMR contributions. It could be established that ED Ni-Co/Cu\nmultilayers do not exhibit an oscillatory GMR behavior with spacer thickness.",
        "positive": "Polymer Nanoreactors Shield Perovskite Nanocrystals from Degradation: Halide perovskite nanocrystals (NCs) have shown impressive advances,\nexhibiting optical properties that outpace conventional semiconductor NCs, such\nas near-unity quantum yields and ultrafast radiative decay rates. Nevertheless,\nthe NCs suffer even more from stability problems at ambient conditions and due\nto moisture than their bulk counterparts. Herein, we report a strategy of\nemploying polymer micelles as nanoreactors for the synthesis of methylammonium\nlead trihalide perovskite NCs. Encapsulated by this polymer shell, the NCs\ndisplay strong stability against water degradation and halide ion migration.\nThin films comprising these NCs exhibit a more than 15-fold increase in\nlifespan in comparison to unprotected NCs in ambient conditions and even\nsurvive over 75 days of complete immersion in water. Furthermore, the NCs,\nwhich exhibit quantum yields of up to 63% and tunability of the emission\nwavelength throughout the visible range, show no signs of halide ion exchange.\nAdditionally, heterostructures of MAPI and MAPBr NC layers exhibit efficient\nF\\\"orster resonance energy transfer (FRET), revealing a strategy for\noptoelectronic integration."
    },
    {
        "anchor": "Friction on incommensurate substrates: Role of anharmonicity and defects: We present Molecular Dynamics simulations of one- and two-dimensional\nbead-spring models sliding on incommensurate substrates. We investigate how\nsliding friction is affected by interaction anharmonicity and structural\ndefects. In their absence, we confirm earlier findings, namely, that at special\nresonance sliding velocities, friction is maximal. When sliding off-resonance,\npartially thermalized states are possible, whereby only a small number of\nvibrational modes becomes excited, but whose kinetic energies are already\nMaxwell-Boltzmann distributed. Anharmonicity and defects typically destroy\npartial thermalization, and instead lead to full thermalization, implying much\nhigher friction. For sliders with periodic boundaries, thermalization begins\nwith vibrational modes whose spatial modulation is compatible with the\nincommensurate lattice. For a disc-shaped slider, modes corresponding to\nmodulations compatible with the slider radius are initially the most dominant.\nBy tuning the mechanical properties of the slider's edge, this effect can be\ncontrolled, resulting in significant changes in the sliding distance covered.",
        "positive": "Ultrafast scattering dynamics of coherent phonons in Bi$_{1-x}$Sb$_{x}$\n  in the Weyl semimetal phase: We investigate ultrafast phonon dynamics in the Bi$_{1-x}$Sb$_{x}$ alloy\nsystem for various compositions $x$ using a reflective femtosecond pump-probe\ntechnique. The coherent optical phonons corresponding to the A$_{1g}$ local\nvibrational modes of Bi-Bi, Bi-Sb, and Sb-Sb are generated and observed in the\ntime domain with a few picoseconds dephasing time. The frequencies of the\ncoherent optical phonons were found to change as the Sb composition $x$ was\nvaried, and more importantly, the relaxation time of those phonon modes was\ndramatically reduced for $x$ values in the range 0.5--0.8. We argue that the\nphonon relaxation dynamics are not simply governed by alloy scattering, but are\nsignificantly modified by anharmonic phonon-phonon scattering with implied\nminor contributions from electron-phonon scattering in a Weyl-semimetal phase."
    },
    {
        "anchor": "Unravelling the contributions to spin-lattice relaxation in Kramers\n  single-molecule magnets: The study of how spin interacts with lattice vibrations and relaxes to\nequilibrium provides unique insights on its chemical environment and the\nrelation between electronic structure and molecular composition. Despite its\nimportance for several disciplines, ranging from magnetic resonance to quantum\ntechnologies, a convincing interpretation of spin dynamics in crystals of\nmagnetic molecules is still lacking due to the challenging experimental\ndetermination of the correct spin relaxation mechanism. We apply ab initio spin\ndynamics to a series of twelve coordination complexes of Co(II) and Dy(III)\nions selected among $\\sim$240 compounds that largely cover the literature on\nsingle-molecule magnets and well represent different regimes of spin\nrelaxation. Simulations reveal that the Orbach spin relaxation rate of known\ncompounds mostly depends on the ions' zero-field splitting and little on the\ndetails of molecular vibrations. Raman relaxation is instead found to be also\nsignificantly affected by the features of low-energy phonons. These results\nprovide a complete understanding of the factors limiting spin lifetime in\nsingle-molecule magnets and revisit years of experimental investigations by\nmaking it possible to transparently distinguish Orbach and Raman relaxation\nmechanisms.",
        "positive": "Electron localization in self-assembled Si/Ge(111) quantum dots: Electron localization in the Si/Ge heterosystem with Si quantum dots (QDs)\nwas studied by transport and electron spin resonance (ESR) measurements. For Si\nQD structures grown on Ge(111) substrates, the ESR signal with g-factor\n$g=2.0022\\pm0.0001$ and ESR line width $\\Delta H\\approx1.2$ Oe was observed and\nattributed to the electrons localized in QDs. The g-factor value was explained\nby taking into account the energy band modification due to strain effects and\nquantum confinement. A strong Ge-Si intermixing in QD structures grown on\nGe(001) is assumed to be main reason of unobserved ESR signal from QDs. The\ntransport behavior confirms the efficient electron localization in Si QDs."
    },
    {
        "anchor": "Low Resistivity and High Breakdown Current Density of 10-nm Diameter van\n  der Waals TaSe3 Nanowires by Chemical Vapor Deposition: Micron-scale single-crystal nanowires of metallic TaSe3, a material that\nforms -Ta-Se3-Ta-Se3- stacks separated from one another by a tubular van der\nWaals (vdW) gap, have been synthesized using chemical vapor deposition (CVD) on\na SiO2/Si substrate, in a process compatible with semiconductor industry\nrequirements. Their electrical resistivity was found unaffected by downscaling\nfrom the bulk to as little as 7 nm in width and height, in striking contrast to\nthe resistivity of copper for the same dimensions. While the bulk resistivity\nof TaSe3 is substantially higher than that of bulk copper, at the nanometer\nscale the TaSe3 wires become competitive to similar-sized copper ones.\nMoreover, we find that the vdW TaSe3 nanowires sustain current densities in\nexcess of 108 A/cm2 and feature an electromigration energy barrier twice that\nof copper. The results highlight the promise of quasi-one-dimensional\ntransition metal trichalcogenides for electronic interconnect applications and\nthe potential of van der Waals materials for downscaled electronics.",
        "positive": "Recombination in polymer-fullerene bulk heterojunction solar cells: Recombination of photogenerated charge carriers in polymer bulk\nheterojunction (BHJ) solar cells reduces the short circuit current (Jsc) and\nthe fill factor (FF). Identifying the mechanism of recombination is, therefore,\nfundamentally important for increasing the power conversion efficiency. Light\nintensity and temperature dependent current-voltage measurements on polymer BHJ\ncells made from a variety of different semiconducting polymers and fullerenes\nshow that the recombination kinetics are voltage dependent and evolve from\nfirst order recombination at short circuit to bimolecular recombination at open\ncircuit as a result of increasing the voltage-dependent charge carrier density\nin the cell. The \"missing 0.3V\" inferred from comparison of the band gaps of\nthe bulk heterojunction materials and the measured open circuit voltage at room\ntemperature results from the temperature dependence of the quasi-Fermi-levels\nin the polymer and fullerene domains - a conclusion based upon the fundamental\nstatistics of Fermions."
    },
    {
        "anchor": "Polaron Self-localization in White-light Emitting Hybrid Perovskites: Two-dimensional (2D) perovskites with general formula $APbX_4$ are attracting\nincreasing interest as solution processable, white-light emissive materials.\nRecent studies have shown that their broadband emission is related to the\nformation of intra-gap color centers; however, the nature and dynamics of the\nemissive species have remained elusive. Here we show that the broadband\nphotoluminescence of the 2D perovskites $(EDBE)PbCl_4$ and $(EDBE)PbBr_4$ stems\nfrom the localization of small polarons within the lattice distortion field.\nUsing a combination of spectroscopic techniques and first-principles\ncalculations, we infer the formation of ${Pb_2}^{3+}$, $Pb^{3+}$, and ${X_2}^-$\n(where X=Cl or Br) species confined within the inorganic perovskite framework.\nDue to strong Coulombic interactions, these species retain their original\nexcitonic character and form self-trapped polaron-excitons acting as radiative\ncolor centers. These findings are expected to be applicable to a broad class of\nwhite-light emitting perovskites with large polaron relaxation energy.",
        "positive": "Plastic flow in solids with interfaces: A non-equilibrium theory of isothermal and diffusionless evolution of\nincoherent interfaces within a plastically deforming solid is developed. The\nirreversible dynamics of the interface are driven by its normal motion,\nincoherency (slip and misorientation), and an intrinsic plastic flow; and\npurely by plastic deformation in the bulk away from the interface. Using the\ncontinuum theory for defect distribution (in bulk and over the interface) we\nformulate a general kinematical framework, derive relevant balance laws and\njump conditions, and prescribe a thermodynamically consistent\nconstitutive/kinetic structure for interface evolution."
    },
    {
        "anchor": "Short range magnetic correlation, metamagnetism and coincident\n  dielectric anomaly in Na$_5$Co$_{15.5}$Te$_6$O$_{36}$: Here we explore the structural, magnetic and dielectric properties of Co\nbased compound Na$_5$Co$_{15.5}$Te$_6$O$_{36}$ as a candidate of short-range\nmagnetic correlations driven development of dielectric anomaly above\nN$\\acute{e}$el temperature of ($T_N$=) 50 K. Low temperature neutron powder\ndiffraction (NPD) in zero applied magnetic field clearly indicates that the\ncanted spin structure is responsible for the antiferromagnetic transition and\npartially occupied Co form short range magnetic correlation with other Co,\nwhich further facilitates the structural distortion and consequent development\nof dielectric anomaly above antiferromagnetic transition. Additionally, the\ntemperature dependent magnetic heat capacity and electron spin resonance\nmeasurements reveal the presence of short-range magnetic correlations which\ncoincides with an anomaly in the dielectric constant vs temperature curve.\nMoreover, significant changes in the lattice parameters are also observed\naround the same temperature, indicating presence of noticeable spin-lattice\ncoupling. Further, sharp jump in the magnetic field dependent magnetization\nclearly indicates the presence of metamagnetic transition and magnetic field\ndependent NPD confirms that rotations of Co spins with applied magnetic field\nare responsible for this metamagnetic phase transition. As a result, this\ntransition causes the magnetocaloric effect to be developed in the system,\nwhich is suitable for the application in low temperature refrigeration.",
        "positive": "Elastic and thermodynamic properties of the shape-memory alloy AuZn: The current work reports on the elastic shear moduli, internal friction, and\nthe specific heat of the B2 cubic ordered alloy AuZn as a function of\ntemperature. Measurements were made on single-crystal and polycrystalline\nsamples using Resonant Ultrasound Spectroscopy (RUS), semi-adiabatic\ncalorimetry and stress-strain measurements. Our results confirm that this alloy\nexhibits the shape-memory effect and a phase transition at 64.75 K that appears\nto be continuous (second-order) from the specific heat data. It is argued that\nthe combination of equiatomic composition and a low transformation temperature\nconstrain the chemical potential and its derivatives to exhibit behavior that\nlies at the borderline between that of a first-order (discontinuous) and a\ncontinuous phase transition. The acoustic dissipation does not peak at the\ntranstion temperature as expected, but shows a maximum well into the\nlow-temperature phase. The Debye temeprature value of 219 K, obtained from the\nlow-temperature specific heat data is in favorable agreement with that\ndetermined from the acoustic data (207 K) above the transition."
    },
    {
        "anchor": "Exact solution for quantum dynamics of a periodically-driven\n  two-level-system: We present a family of exact analytic solutions for non-linear quantum\ndynamics of a two-level system (TLS) subject to a periodic-in-time external\nfield. In constructing the exactly solvable models, we use a \"reverse\nengineering\" approach where the form of external perturbation is chosen to\npreserve an integrability constraint, which yields a single non-linear\ndifferential equation for the ac-field. A solution to this equation is\nexpressed in terms of Jacobi elliptic functions with three independent\nparameters that allows one to choose the frequency, average value, and\namplitude of the time-dependent field at will. This form of the ac-drive is\nespecially relevant to the problem of dynamics of TLS charge defects that cause\ndielectric losses in superconducting qubits. We apply our exact results to\nanalyze non-linear dielectric response of such TLSs and show that the position\nof the resonance peak in the spectrum of the relevant correlation function is\ndetermined by the quantum-mechanical phase accumulated by the TLS wave-function\nover a time evolution cycle. It is shown that in the non-linear regime, this\nresonance frequency may be shifted strongly from the value predicted by the\ncanonical TLS model. We also analyze the \"spin\" survival probability in the\nregime of strong external drive and recover a coherent destruction of tunneling\nphenomenon within our family of exact solutions, which manifests itself as a\nstrong suppression of \"spin-flip\" processes and suggests that such non-linear\ndynamics in LC-resonators may lead to lower losses.",
        "positive": "Ion-Induced Surface Diffusion in Ion Sputtering: Ion bombardment is known to enhance surface diffusion and affect the surface\nmorphology. To quantify this phenomenon we calculate the ion-induced diffusion\nconstant and its dependence on the ion energy, flux and angle of incidence. We\nfind that ion bombardment can both enhance and suppress diffusion and that the\nsign of the diffusion constant depends on the experimental parameters. The\neffect of ion-induced diffusion on ripple formation and roughening of\nion-sputtered surfaces is discussed and summarized in a morphological phase\ndiagram."
    },
    {
        "anchor": "Design of a low band gap oxide ferroelectric: Bi$_6$Ti$_4$O$_{17}$: A strategy for obtaining low band gap oxide ferroelectrics based on charge\nimbalance is described and illustrated by first principles studies of the\nhypothetical compound Bi$_6$Ti$_4$O$_{17}$, which is an alternate stacking of\nthe ferroelectric Bi$_4$Ti$_3$O$_{12}$. We find that this compound is\nferroelectric, similar to Bi$_4$Ti$_3$O$_{12}$ although with a reduced\npolarization. Importantly, calculations of the electronic structure with the\nrecently developed functional of Tran and Blaha yield a much reduced band gap\nof 1.83 eV for this material compared to Bi$_4$Ti$_3$O$_{12}$. Therefore,\nBi$_6$Ti$_4$O$_{17}$ is predicted to be a low band gap ferroelectric material.",
        "positive": "State of the Art Development on Solid-State Lithium Batteries: Solid-state lithium batteries (SLBs) offers a promising avenue for the\ndevelopment of next-generation lithium-ion batteries with ultrahigh energy\ndensity and safety performance. This review provides a quick overview of the\nstate-of-the-art development of anode, cathode, solid electrolyte of SLBs and\nthe observation of ion transport in the cell during the past half year in 2023.\nOther important developments for SLIBs such as high safety and performance\nstrategies have also been provided."
    },
    {
        "anchor": "Moir\u00e9 patterns and inversion boundaries in graphene/hexagonal boron\n  nitride bilayers: In this paper a systematic examination of graphene/hexagonal boron nitride\n(g/hBN) bilayers is presented, through a recently developed two-dimensional\nphase field crystal model that incorporates out-of-plane deformations. The\nsystem parameters are determined by closely matching the stacking energies and\nheights of graphene/hBN bilayers to those obtained from existing\nquantum-mechanical density functional theory calculations. Out-of-plane\ndeformations are shown to reduce the energies of inversion domain boundaries in\nhBN, and the coupling between graphene and hBN layers leads to a bilayer defect\nconfiguration consisting of an inversion boundary in hBN and a domain wall in\ngraphene. Simulations of twisted bilayers reveal the structure, energy, and\nelastic properties of the corresponding Moir\\'e patterns, and show a crossover,\nas the misorientation angle between the layers increases, from a well-defined\nhexagonal network of domain boundaries and junctions to smeared-out patterns.\nThe transition occurs when the thickness of domain walls approaches the size of\nthe Moir\\'e patterns, and coincides with the peaks in the average von Mises and\nvolumetric stresses of the bilayer.",
        "positive": "Critical test for Altshuler-Aronov theory: Evolution of the density of\n  states singularity in double perovskite Sr$_2$FeMoO$_6$ with controlled\n  disorder: With high-resolution photoemission spectroscopy measurements, the density of\nstates (DOS) near the Fermi level ($E_\\mathrm{F}$) of double perovskite\nSr$_2$FeMoO$_6$ having different degrees of Fe/Mo antisite disorder has been\ninvestigated with varying temperature. The DOS near $E_\\mathrm{F}$ showed a\nsystematic depletion with increasing degree of disorder, and recovered with\nincreasing temperature. Altshuler-Aronov (AA) theory of disordered metals well\nexplains the dependences of the experimental results. Scaling analysis of the\nspectra provides experimental indication for the functional form of the AA DOS\nsingularity."
    },
    {
        "anchor": "Suppression of the Shear Raman Mode in Defective Bilayer MoS2: We investigate the effects of lattice disorders on the low frequency Raman\nspectra of bilayer MoS2. The bilayer MoS2 was subjected to defect engineering\nby irradiation with a 30 keV He+ ion beam and the induced morphology change was\ncharacterized by transmission electron microscopy. With increasing ion dose the\nshear mode is observed to redshift and it is also suppressed sharply compared\nto other Raman peaks. We use the linear chain model to describe the changes to\nthe Raman spectra. Our observations suggest that crystallite size and\norientation are the dominant factors behind the changes to the Raman spectra.",
        "positive": "Binder-free CNT cathodes for Li-O$_2$ batteries with more than one life: Li-O$_2$ batteries (LOB) performance degradation ultimately occurs through\nthe accumulation of discharge products and irreversible clogging of the porous\nelectrode during the cycling. Electrode binder degradation in the presence of\nreduced oxygen species can result in additional coating of the conductive\nsurface, exacerbating capacity fading. Herein, we establish a facile method to\nfabricate free-standing, binder-free electrodes for LOBs in which multi-wall\ncarbon nanotubes (MWCNT) form cross-linked networks exhibiting high porosity,\nconductivity, and flexibility. These electrodes demonstrate high\nreproducibility upon cycling in LOBs. After cell death, efficient and\ninexpensive methods to wash away the accumulated discharge products are\ndemonstrated, as reconditioning method. The second life usage of these\nelectrodes is validated, without noticeable loss of performance. These findings\naim to assist in the development of greener high energy density batteries while\nreducing manufacturing and recycling costs."
    },
    {
        "anchor": "Materials Science and Protein Crystallography Using the MX Beamline\n  Control Toolkit: MX is a portable beamline control system that has been described at previous\nNOBUGS meetings. This talk will briefly review MX and then discuss important\nchanges and improvements made since the last meeting in 2000.\n  For materials science, work has focused on extending the support for\nmultichannel analyzers and for fast data acquisition using quick scans. MX MCA\nsupport has focused on the development of interfaces to the X-Ray\nInstrumentation Associates DXP-2X and X10P (Saturn) MCAs. The MX DXP-2X support\nhas been used by MR-CAT at the Advanced Photon Source to readout a 13-element\nGe detector at input count rates of up to 1.5*10^6 counts per second per\ndetector channel. The other major addition is support for quick scans using\nmultichannel scalers. Quick scanning is now routinely used for XAFS and\ndiffraction measurements at MR-CAT and will soon be implemented on some MX\ncrystallography beamlines as well. We have also begun work to allow XIA MCAs to\nbe read out during quick scans.\n  For protein crystallography, we have primarily focused on implementing MX for\nnew beamlines, namely, SER-CAT at the APS and GCPCC at CAMD, with others\npending at the APS. Progress has also been made on the integration of MX with\nvendor CCD and robotics software.",
        "positive": "Radial Stark effect in (In,Ga)N nanowires: We study the luminescence of unintentionally doped and Si-doped\nIn$_x$Ga$_{1-x}$N nanowires with a low In content (x<0.2) grown by molecular\nbeam epitaxy on Si substrates. The emission band observed at 300 K from the\nunintentionally doped samples is centered at much lower energies (800 meV) than\nexpected from the In content measured by x-ray diffractometry and energy\ndispersive x-ray spectroscopy. This discrepancy arises from the pinning of the\nFermi level at the sidewalls of the nanowires, which gives rise to strong\nradial built-in electric fields. The combination of the built-in electric\nfields with the compositional fluctuations inherent to (In,Ga)N alloys induces\na competition between spatially direct and indirect recombination channels. At\nelevated temperatures, electrons at the core of the nanowire recombine with\nholes close to the surface, and the emission from unintentionally doped\nnanowires exhibits a Stark shift of several hundreds of meV. The competition\nbetween spatially direct and indirect transitions is analyzed as a function of\ntemperature for samples with various Si concentrations. We propose that the\nradial Stark effect is responsible for the broadband absorption of (In,Ga)N\nnanowires across the entire visible range, which makes these nanostructures a\npromising platform for solar energy applications."
    },
    {
        "anchor": "Effect of p-d hybridization and structural distortion on the electronic\n  properties of AgAlM2 (M = S, Se, Te) chalcopyrite semiconductors: We have carried out ab-initio calculation and study of structural and\nelectronic properties of AgAlM2 (M = S, Se, Te) chalcopyrite semiconductors\nusing Density Functional Theory (DFT) based self consistent Tight binding\nLinear Muffin Tin orbital (TB-LMTO) method. Calculated equlibrium values of\nlattice constants, anion displacement parameter (u), tetragonal distortion\n({\\eta} = c/2a) and bond lengths have good agreement with experimental values.\nOur study suggests these semiconductors to be direct band gap semiconductors\nwith band gaps 1.98 eV, 1.59 eV and 1.36 eV respectively. These are in good\nagreement with experimental value within the limitation of local density\napproximation (LDA). Our explicit study of the effects of anion displacement\nand p-d hybridization show that band gap increases by 9.8%, 8.2% and 5.1%\nrespectively for AgAlM2 (M = S, Se, Te) due to former effect and decreases by\n51%, 47% and 42% respectively due to later effect.",
        "positive": "Spin injection in a single metallic nanoparticle: a step towards\n  nanospintronics: We have fabricated nanometer sized magnetic tunnel junctions using a new\nnanoindentation technique in order to study the transport properties of a\nsingle metallic nanoparticle. Coulomb blockade effects show clear evidence for\nsingle electron tunneling through a single 2.5 nm Au cluster. The observed\nmagnetoresistance is the signature of spin conservation during the transport\nprocess through a non magnetic cluster."
    },
    {
        "anchor": "Pressure-induced diamond to beta-tin transition in bulk silicon: a\n  near-exact quantum Monte Carlo study: The pressure-induced structural phase transition from diamond to beta-tin in\nsilicon is an excellent test for theoretical total energy methods. The\ntransition pressure provides a sensitive measure of small relative energy\nchanges between the two phases (one a semiconductor and the other a semimetal).\nExperimentally, the transition pressure is well characterized.\nDensity-functional results have been unsatisfactory. Even the generally much\nmore accurate diffusion Monte Carlo method has shown a noticeable fixed-node\nerror. We use the recently developed phaseless auxiliary-field quantum Monte\nCarlo (AFQMC) method to calculate the relative energy differences in the two\nphases. In this method, all but the error due to the phaseless constraint can\nbe controlled systematically and driven to zero. In both structural phases we\nwere able to benchmark the error of the phaseless constraint by carrying out\nexact unconstrained AFQMC calculations for small supercells. Comparison between\nthe two shows that the systematic error in the absolute total energies due to\nthe phaseless constraint is well within 0.5 mHa/atom. Consistent with these\ninternal benchmarks, the transition pressure obtained by the phaseless AFQMC\nfrom large supercells is in very good agreement with experiment.",
        "positive": "Ab initio analysis of electron-phonon coupling in molecular devices: We report first principles analysis of electron-phonon coupling in molecular\ndevices under external bias voltage and during current flow. Our theory and\ncomputational framework are based carrying out density functional theory within\nthe Keldysh nonequilibrium Green's function formalism. We analyze which\nmolecular vibrational modes are most relevant to charge transport under\nnonequilibrium conditions. For a molecular tunnel junction of a\n1,4-benzenedithiolate molecule contacted by two leads, the low-lying modes of\nthe vibration are found to be most important. As a function of bias voltage,\nthe electron-phonon coupling strength can change drastically while the\nvibrational spectrum changes at a few percent level."
    },
    {
        "anchor": "Band offsets at the crystalline/amorphous silicon interface from\n  first-principles: The band offsets between crystalline and hydrogenated amorphous silicon\n(a-Si:H) are key parameters governing the charge transport in modern silicon\nhetrojunction solar cells. They are an important input for macroscopic\nsimulators that are used to further optimize the solar cell. Past experimental\nstudies, using X-ray photoelectron spectroscopy (XPS) and capacitance-voltage\nmeasurements, have yielded conflicting results on the band offset. Here we\npresent a computational study on the band offsets. It is based on atomistic\nmodels and density-functional theory (DFT). The amorphous part of the interface\nis obtained by relatively long DFT first-principles molecular-dynamics (MD)\nruns at an elevated temperature on 30 statistically independent samples. In\norder to obtain a realistic conduction band position the electronic structure\nof the interface is calculated with a hybrid functional. We find a slight\nasymmetry in the band offsets, where the offset in the valence band (0.30 eV)\nis larger than in the conduction band (0.17 eV). Our results are in agreement\nwith the latest XPS measurements that report a valence band offset of 0.3 eV\n[M. Liebhaber et al., Appl. Phys. Lett. 106, 031601 (2015)].",
        "positive": "Theoretical study on magnetic tunneling junctions with semiconductor\n  barriers CuInSe$_2$ and CuGaSe$_2$ including a detailed analysis of\n  band-resolved transmittances: We study spin-dependent transport properties in magnetic tunneling junctions\n(MTJs) with semiconductor barriers, Fe/CuInSe$_2$/Fe(001) and\nFe/CuGaSe$_2$/Fe(001). By analyzing their transmittances at zero bias voltage\non the basis of the first-principles calculations, we find that spin-dependent\ncoherent tunneling transport of $\\Delta_1$ wave functions yields a relatively\nhigh magnetoresistance (MR) ratio in both the MTJs. We carry out a detailed\nanalysis of the band-resolved transmittances in both the MTJs and find an\nabsence of the selective transmission of $\\Delta_1$ wave functions in some\nenergy regions a few eV away from the Fermi level due to small band gaps in\nCuInSe$_2$ and CuGaSe$_2$."
    },
    {
        "anchor": "Geometry of Adaptive Martensite in Ni-Mn-based Heusler alloys: Modulated martensites play an important role in magnetic shape memory alloys,\nbecause all functional properties are closely connected to the twin\nmicrostructure and the phase boundary. The nature of the modulated martensites\nis still unclear. One approach is the concept of adaptive martensite, which\nregards all modulated phases as nanotwinned microstructures. In this article,\nwe use the Ni-Mn-based shape memory alloys as an example to show the geometric\nrationale behind this concept using analytic equations based on the\nphenomenological theory of martensite. This could enhance discussions about the\nimplications of the adaptive martensite by showing the exact relations between\nthe various unit cells used to describe the structure. We use the concept to\ndiscuss the compatibility at the habit plane, the nature of high-order twin\nboundaries and the dependence of the lattice constants on the different types\nof modulation.",
        "positive": "Crack propagation in quasicrystals: Crack propagation is studied in a two dimensional decagonal model\nquasicrystal. The simulations reveal the dominating role of highly coordinated\natomic environments as structure intrinsic obstacles for both dislocation\nmotion and crack propagation. For certain overloads, these obstacles and the\nquasiperiodic nature of the crystal result in a specific crack propagation\nmechanism: The crack tip emits a dislocation followed by a phason wall, along\nwhich the material opens up."
    },
    {
        "anchor": "Micro and nano patternable magnetic carbon: Carbon is conventionally not associated with magnetism, and much of the\ndiscussion of its nanotechnology perspectives appears to be centered on its\nelectron transport properties. Among the few existing examples of magnetic\ncarbon production, none has found a direct applicability in scalable micro and\nnano fabrication, Here we introduce a paramagnetic form of carbon whose\nprecursor polymers can be lithographically patterned into micro and nano\nstructures prior to pyrolysis. This unreactive and thermally robust material\nfeatures strong room-temperature paramagnetism owing to a large number of\nunpaired electrons with restricted mobility, which is achieved by controlling\nthe progression of bond dissociation and formation during pyrolysis. The\nmanufacture of this magnetic carbon, having (3.97 x 0.8) 10^17 spins/ mg, can\nimmediately benefit a number of spintronic and magnetic MEMS applications, and\nalso shed light on the controversial theories concerning the existence and\nmechanisms of magnetism in carbon.",
        "positive": "Ab-initio investigation of finite size effects in rutile titania\n  nanoparticles with semilocal and nonlocal density functionals: In this work, we employ hybrid and generalized gradient approximation (GGA)\nlevel density functional theory (DFT) calculations to investigate the\nconvergence of surface properties and band structure of rutile titania\n(TiO$_2$) nanoparticles with particle size. The surface energies and band\nstructures are calculated for cuboidal particles with minimum dimension ranging\nfrom 3.7 \\r{A} (24 atoms) to 10.3 \\r{A} (384 atoms) using a highly-parallel\nreal-space DFT code to enable hybrid level DFT calculations of larger\nnanoparticles than are typically practical. We deconvolute the geometric and\nelectronic finite size effects in surface energy, and evaluate the influence of\ndefects on band structure and density of states (DOS). The electronic finite\nsize effects in surface energy vanish when the minimum length scale of the\nnanoparticles becomes greater than 10 \\r{A}. We show that this length scale is\nconsistent with a computationally efficient numerical analysis of the\ncharacteristic length scale of electronic interactions. The surface energy of\nnanoparticles having minimum dimension beyond this characteristic length can be\napproximated using slab calculations that account for the geometric defects. In\ncontrast, the finite size effects on the band structure is highly dependent on\nthe shape and size of these particles. The DOS for cuboidal particles and more\nrealistic particles constructed using the Wulff algorithm reveal that defect\nstates within the bandgap play a key role in determining the band structure of\nnanoparticles and the bandgap does not converge to the bulk limit for the\nparticle sizes investigated."
    },
    {
        "anchor": "Grain and Grain Boundary Segmentation using Machine Learning with Real\n  and Generated Datasets: We report significantly improved accuracy of grain boundary segmentation\nusing Convolutional Neural Networks (CNN) trained on a combination of real and\ngenerated data. Manual segmentation is accurate but time-consuming, and\nexisting computational methods are faster but often inaccurate. To combat this\ndilemma, machine learning models can be used to achieve the accuracy of manual\nsegmentation and have the efficiency of a computational method. An extensive\ndataset of from 316L stainless steel samples is additively manufactured,\nprepared, polished, etched, and then microstructure grain images were\nsystematically collected. Grain segmentation via existing computational methods\nand manual (by-hand) were conducted, to create \"real\" training data. A Voronoi\ntessellation pattern combined with random synthetic noise and simulated\ndefects, is developed to create a novel artificial grain image fabrication\nmethod. This provided training data supplementation for data-intensive machine\nlearning methods. The accuracy of the grain measurements from microstructure\nimages segmented via computational methods and machine learning methods\nproposed in this work are calculated and compared to provide much benchmarks in\ngrain segmentation. Over 400 images of the microstructure of stainless steel\nsamples were manually segmented for machine learning training applications.\nThis data and the artificial data is available on Kaggle.",
        "positive": "Thermally triggered phononic gaps in liquids at THz scale: In this paper we present inelastic X-ray scattering experiments in a diamond\nanvil cell and molecular dynamic simulations to investigate the behavior of\nphononic excitations in liquid Ar. The spectra calculated using molecular\ndynamics were found to be in a good agreement with the experimental data.\nFurthermore, we observe that, upon temperature increases, a low-frequency\ntransverse phononic gap emerges while high-frequency propagating modes become\nevanescent at the THz scale. The effect of strong localization of a\nlongitudinal phononic mode in the supercritical phase is observed for the first\ntime. The evidence for the high-frequency transverse phononic gap due to the\ntransition from an oscillatory to a ballistic dynamic regimes of motion is\npresented and supported by molecular dynamics simulations. This transition\ntakes place across the Frenkel line thermodynamic limit which demarcates\ncompressed liquid and non-compressed fluid domains on the phase diagram and is\nsupported by calculations within the Green-Kubo phenomenological formalism.\nThese results are crucial to advance the development of novel terahertz thermal\ndevices, phononic lenses, mirrors, and other THz metamaterials."
    },
    {
        "anchor": "Comment on 'Symmetry and random sampling of symmetry independent\n  configurations for the simulation of disordered solids': The proposed algorithm by Philippe D'Arco et al. 2013 J. Phys.: Condens.\nMatter 25 355401 was not well compared with other possible solutions for\nsymmetry independent configuration (SIC) generation. In this comment, three\nwell known solutions of SIC searching are discussed: exhaustive explorations,\npure random sampling and \"symmetry imposed\" approaches. It is shown, that the\nadvantages of the algorithm published by Philippe D'Arco et al. are\nquestionable.",
        "positive": "Zero-point quantum swing of magnetic couples: Quantum fluctuations are ubiquitous in physics. Ranging from conventional\nexamples like the harmonic oscillator to intricate theories on the origin of\nthe universe, they alter virtually all aspects of matter -- including\nsuperconductivity, phase transitions and nanoscale processes. As a rule of\nthumb, the smaller the object, the larger their impact. This poses a serious\nchallenge to modern nanotechnology, which aims total control via atom-by-atom\nengineered devices. In magnetic nanostructures, high stability of the magnetic\nsignal is crucial when targeting realistic applications in information\ntechnology, e.g. miniaturized bits. Here, we demonstrate that zero-point\nspin-fluctuations are paramount in determining the fundamental magnetic\nexchange interactions that dictate the nature and stability of the magnetic\nstate. Hinging on the fluctuation-dissipation theorem, we establish that\nquantum fluctuations correctly account for the large overestimation of the\ninteractions as obtained from conventional static first-principles frameworks,\nfilling in a crucial gap between theory and experiment [1,2]. Our analysis\nfurther reveals that zero-point spin-fluctuations tend to promote the\nnon-collinearity and stability of chiral magnetic textures such as skyrmions --\na counter-intuitive quantum effect that inspires practical guidelines for\ndesigning disruptive nanodevices."
    },
    {
        "anchor": "Plate Acoustic Waves in ZX-cut Lithium Niobate: Plate acoustic waves (PAW) propagating along X-axis in the Z-cut wafer of a\nsingle crystal of lithium niobate are considered theoretically and\nexperimentally. For eight lowest PAW modes, the dispersion curves for\nwavenumber k(f) are calculated by the equations of motion and electrodynamics,\nby the Finite Element Method, and then measured experimentally. The spectra\nk(f) obtained by the numerical solution and FEM-simulation are in good\nagreement, and experimental measurements agree with theoretical predictions.\nThe PAW modes are identified by the components of their total acoustic\ndisplacements and cutoff frequencies. Analysis of the longitudinal and normal\nacoustical displacements permits to find PAW mode capable for usage in\nultrasonic actuators. The results obtained may be useful for ultrasonic\ntransducers, acousto-electronic and acousto-optic applications, and ultrasonic\nmotors/actuators fabricated in the Z-cut ferroelectric lithium niobate wafers\nincluding periodically poled wave-guides.",
        "positive": "Sub-diffraction sub-100 ps all-optical magnetic switching by passive\n  wavefront shaping: The recently discovered magnetization reversal driven solely by a femtosecond\nlaser pulse has been shown to be a promising way to record information at\nrecord breaking speeds. Seeking to improve the recording density has raised\nintriguing fundamental question about the feasibility to combine the ultrafast\ntemporal with sub-wavelength spatial resolution of magnetic recording. Here we\nreport about the first experimental demonstration of sub-diffraction and\nsub-100 ps all-optical magnetic switching. Using computational methods we\nreveal the feasibility of sub-diffraction magnetic switching even for an\nunfocused incoming laser pulse. This effect is achieved via structuring the\nsample such that the laser pulse experiences a passive wavefront shaping as it\ncouples and propagates inside the magnetic structure. Time-resolved studies\nwith the help of photo-emission electron microscopy clearly reveal that the\nsub-wavelength switching with the help of the passive wave-front shaping can be\npushed into sub-100 ps regime."
    },
    {
        "anchor": "Spin-polarized current effect on antiferromagnet magnetization in a\n  ferromagnet - antiferromagnet nanojunction: Theory and simulation: Spin-polarized current effect is studied on the static and dynamic\nmagnetization of the antiferromagnet in a ferromagnet - antiferromagnet\nnanojunction. The macrospin approximation is generalized to antiferromagnets.\nCanted antiferromagnetic configuration and resulting magnetic moment are\ninduced by an external magnetic field. The resonance frequency and damping are\ncalculated, as well as the threshold current density corresponding to\ninstability appearance. A possibility is shown of generating low-damping\nmagnetization oscillations in terahertz range. The fluctuation effect is\ndiscussed on the canted antiferromagnetic configuration. Numerical simulation\nis carried out of the magnetization dynamics of the antiferromagnetic layer in\nthe nanojunction with spin-polarized current. Outside the instability range,\nthe simulation results coincide completely with analytical calculations using\nlinear approximation. In the instability range, undamped oscillations occur of\nthe longitudinal and transverse magnetization components.",
        "positive": "Positrons in Surface Physics: Within the last decade powerful methods have been developed to study surfaces\nusing bright low-energy positron beams. These novel analysis tools exploit the\nunique properties of positron interaction with surfaces, which comprise the\nabsence of exchange interaction, repulsive crystal potential and positron\ntrapping in delocalized surface states at low energies. By applying reflection\nhigh-energy positron diffraction (RHEPD) one can benefit from the phenomenon of\ntotal reflection below a critical angle that is not present in electron surface\ndiffraction. Therefore, RHEPD allows the determination of the atom positions of\n(reconstructed) surfaces with outstanding accuracy. The main advantages of\npositron annihilation induced Auger-electron spectroscopy (PAES) are the\nmissing secondary electron background in the energy region of Auger-transitions\nand its topmost layer sensitivity for elemental analysis. In order to enable\nthe investigation of the electron polarization at surfaces low-energy\nspin-polarized positrons are used to probe the outermost electrons of the\nsurface. Furthermore, in fundamental research the preparation of well defined\nsurfaces tailored for the production of bound leptonic systems plays an\noutstanding role. In this report, it is envisaged to cover both, the\nfundamental aspects of positron surface interaction and the present status of\nsurface studies using modern positron beam techniques."
    },
    {
        "anchor": "Non Destructive Determination Of Elastic Moduli By Two Dimensional\n  Fourier Transformation And Laser Ultrasonic Technique: Broadband laser ultrasonics and two dimensional Fourier transformation are\nused to characterize the properties of varieties of foils and plates. Laser\nultrasonics generation is achieved by use of a pulsed laser which deposits\npulsed laser energy on the surface of the specimen. The displacement amplitude\nof the resulting broadband ultrasonic modes are monitored using a two wave\nmixing photo-refractive interferometer. By applying a two dimensional Fourier\ntransformation to the detected spatial and temporal displacement waveforms, the\nimages of density of state (DOS) for the excited ultrasounds are obtained.\nResults are presented for a 150 um thick paper sample, a 52.8 um stainless\nsteel foil and a 1.27 mm thick aluminum plate. The DOS image demonstrates the\nability to measure the properties of each generated ultrasonic modes and\nprovides a direct, non destructive, measure of elastic moduli of the tested\nspecimens",
        "positive": "Superquasicrystals: selfsimilar ordered structures with\n  non-crystallographic point symmetries: We present a systematic method of constructing limit-quasiperiodic structures\nwith non-crystallographic point symmetries. Such structures are different\naperiodic ordered structures from quasicrystals, and we call them\n\"superquasicrystals\". They are sections of higher-dimensional limit-periodic\nstructures constructed on \"super-Bravais-lattices\". We enumerate important\nsuper-Bravais-lattices. Superquasicrystals with strong selfsimilarities form an\nimportant subclass. A simplest example is a two-dimensional octagonal\nsuperquasicrystal."
    },
    {
        "anchor": "A Cosserat crystal plasticity and phase field theory for grain boundary\n  migration: The microstructure evolution due to thermomechanical treatment of metals can\nlargely be described by viscoplastic deformation, nucleation and grain growth.\nThese processes take place over different length and time scales which present\nsignificant challenges when formulating simulation models. In particular, no\noverall unified field framework exists to model concurrent viscoplastic\ndeformation and recrystallization and grain growth in metal polycrystals. In\nthis work a thermodynamically consistent diffuse interface framework\nincorporating crystal viscoplasticity and grain boundary migration is\nelaborated. The Kobayashi--Warren--Carter (KWC) phase field model is extended\nto incorporate the full mechanical coupling with material and lattice rotations\nand evolution of dislocation densities. The Cosserat crystal plasticity theory\nis shown to be the appropriate framework to formulate the coupling between\nphase field and mechanics with proper distinction between bulk and grain\nboundary behaviour.",
        "positive": "Electrically tunable g-factors in quantum dot molecular spin states: We present a magneto-photoluminescence study of individual vertically stacked\nInAs/GaAs quantum dot pairs separated by thin tunnel barriers. As an applied\nelectric field tunes the relative energies of the two dots, we observe a strong\nresonant increase or decrease in the g-factors of different spin states that\nhave molecular wavefunctions distributed over both quantum dots. We propose a\nphenomenological model for the change in g-factor based on resonant changes in\nthe amplitude of the wavefunction in the barrier due to the formation of\nbonding and antibonding orbitals."
    },
    {
        "anchor": "Large Rashba splittings in bulk and monolayer of BiAs: Two-dimensional materials with Rashba split bands near the Fermi level are\nkey to developing upcoming next-generation spintronics. They enable generating,\ndetecting, and manipulating spin currents without an external magnetic field.\nHere, we propose BiAs as a novel layered semiconductor with large Rashba\nsplitting in bulk and monolayer forms. Using first-principles calculations, we\ndetermined the lowest energy structure of BiAs and its basic electronic\nproperties. Bulk BiAs has a layered crystal structure with two atoms in a\nrhombohedral primitive cell, similar to the parent Bi and As elemental phases.\nIt is a semiconductor with a narrow and indirect band gap. The spin-orbit\ncoupling leads to Rashba-Dresselhaus spin splitting and characteristic spin\ntexture around the L-point in the Brillouin zone of the hexagonal conventional\nunit cell, with Rashba energy and Rashba coupling constant for valence\n(conduction) band of $E_R$= 137 meV (93 meV) and $\\alpha_R$= 6.05 eV\\AA~(4.6\neV{\\AA}). In monolayer form (i.e., composed of a BiAs bilayer), BiAs has a much\nlarger and direct band gap at $\\Gamma$, with a circular spin texture\ncharacteristic of a pure Rashba effect. The Rashba energy $E_R$= 18 meV and\nRashba coupling constant $\\alpha_R$= 1.67 eV{\\AA} of monolayer BiAs are quite\nlarge compared to other known 2D materials, and these values are shown to\nincrease under tensile biaxial strain.",
        "positive": "High-throughput nanoparticle analysis in a FEG-SEM using an inexpensive\n  multi-sample STEM-ADF system: Nanotechnology research requires the routine use of characterization methods\nwith high spatial resolution. These experiments are rather costly, not only\nfrom the point of view of the expensive microscopes, but also considering the\nneed of a rather specialized equipment operator. Here, we describe the\nconstruction of an inexpensive and simple device that allows the analysis of\nnanoparticle in a FEG-SEM; images can be generated at high magnifications (ex.\nx500.000) and with nanometric resolution. It is based on the acquisition of\ntransmitted electrons annular dark field (TE-ADF) signal; the systems can carry\nup to 16 TEM samples and, it is compatible with SEM sample exchange air-lock.\nPerformance test have shown the measured ADF signal showed the atomic number\nand thickness dependence for transition metal nanoparticle about 10 nm in\ndiameter. Also, the signal quality is high enough that the determination of the\nhistogram of size distribution can be performed using a conventional image\nprocessing software, for gold particles in the range of 2-10 nm in diameter.\nThe developed ADF device allows a much faster and cheaper high spatial\nresolution imaging of nanoparticle samples for routine morphological\ncharacterization and, provides an invaluable high throughput tool for an\nefficient sample screening."
    },
    {
        "anchor": "Phase-field crystal study of grain-boundary premelting: We study the phenomenon of grain-boundary premelting for temperatures below\nthe melting point in the phase-field crystal model of a pure material with\nhexagonal ordering in two dimensions. We investigate the structures of\nsymmetric tilt boundaries as a function of misorientation for two different\ninclinations and compute in the grand canonical ensemble the disjoining\npotential V(w) that governs the fundamental interaction between crystal-melt\ninterfaces as a function of the premelted layer width w. The results reveal\nqualitatively different behaviors for high-angle grain boundaries that are\nuniformly wetted, with w diverging logarithmically as the melting point is\napproached from below, and low-angle boundaries that are punctuated by liquid\npools surrounding dislocations, separated by solid bridges. This qualitative\ndifference between high and low angle boundaries is reflected in the\nw-dependence of the disjoining potential that is purely repulsive (V'(w)<0 for\nall w) above a critical misorientation, but switches from repulsive at small w\nto attractive at large w for low angles. In the latter case, V(w) has a minimum\nthat corresponds to a premelted boundary of finite width at the melting point.\nFurthermore, we find that the standard wetting condition (the grain boundary\nenergy is equal to twice the solid-liquid free energy) gives a much too low\nestimate of the critical misorientation when a low-temperature value of the\ngrain boundary energy is used. In contrast, a reasonable estimate is obtained\nif the grain boundary energy is extrapolated to the melting point, taking into\naccount both the elastic softening of the material at high temperature and\nlocal melting around dislocations.",
        "positive": "Complex chiral columns made of achiral quinoxaline derivatives with\n  semi-flexible cores: Mesogenic materials, quinoxaline derivatives with semi-flexible cores, are\nreported to form new type of 3D columnar structure with large crystallographic\nunit cell and Fddd symmetry below columnar hexagonal phase. The 3D columnar\nstructure is a result of frustration imposed by arrangement of helical columns\nof opposite chirality into triangular lattice. The studied materials exhibit\nfluorescent properties that could be easily tuned by modification of molecular\nstructure, compounds with the extended {\\pi} electron conjugated systems form\naggregates and fluorescence is quenched. For molecules with flexible structure\nthe fluorescence quantum yield reaches 25%. On the other hand, compounds with\nmore rigid mesogenic core, for which fluorescence is suppressed show strong\nhole photocurrent. For some materials also bi-polar: hole and electron transfer\nwas observed."
    },
    {
        "anchor": "Augmentation of the Electron Counting Rule with Ising Model: On semiconductor growth surfaces, surface reconstructions appear. Estimation\nof the reconstructed structures is essential for understanding and controlling\ngrowth phenomena. In this study, the stability of a mixture of two different\nsurface reconstructions is investigated. Since the number of candidate\nstructures is enormous, the structures sampled by Bayesian optimization are\nanalyzed. As a result, the local electron counting (EC) rule alone was found to\nbe insufficient to explain such stability. Then, augmenting the EC rule, a\ndata-driven Ising model is proposed. The model allows the evaluation of the\nwhole enormous number of candidate structures. The approach is expected to be\nuseful for theoretical studies of such mixtures on various semiconductor\nsurfaces.",
        "positive": "Electronic structure and optoelectronic properties of halide double\n  perovskites: Fundamental insights and design of a theoretical workflow: Like single perovskites, halide double perovskites (HDP) have truly emerged\nas efficient optoelectronic materials since they display superior stability and\nare free of toxicity. However, challenges still exist due to either wide and\nindirect bandgaps or parity-forbidden transitions in many of them. The lack of\nunderstanding in chemical bonding and the formation of parity-driven valence\nand conduction band edge states have hindered the design of optoelectronically\nefficient HDPs. In this study, we have developed a theoretical workflow using a\nmulti-integrated approach involving ab-initio density functional theory (DFT)\ncalculations, model Hamiltonian studies, and molecular orbital picture leading\nto momentum matrix element (MME) estimation. This workflow gives us detailed\ninsight into chemical bonding and parity-driven optical transition between edge\nstates. In the process, we have developed a band-projected molecular orbital\npicture (B-MOP) connecting free atomic orbital states obtained at the\nHartree-Fock level and orbital-resolved DFT bands. From the B-MOP, we show that\nthe nearest neighbor cation-anion interaction determines the position of\natom-resolved band states, while the second neighbor cation-cation interactions\ndetermine the shape and width of band dispersion and, thereby, MME. The latter\nis critical to quantify the optical absorption coefficient. Considering both\nB-MOP and MME, we demonstrate a mechanism of tailoring bandgap and optical\nabsorptions through chemical doping at the cation sites. Furthermore, the cause\nof bandgap bowing, a common occurrence in doped HDPs, is explained by ascribing\nit to chemical effect and structural distortion."
    },
    {
        "anchor": "Towards large-area and defects-free growth of phosphorene on Nickel: Low-dimensional materials synthesis based on phosphorus atoms is under\nintense study, and it is still one of the big challenges. Phosphorene, a\nmonolayer of black phosphorus, is one of the most promising candidates for\ntransistor and photonics devices at atomistic thickness. However, the lack of\nlarge-scale and defects-free growth significantly obstructs its device\ndevelopment. Here, we demonstrate the large-scale and defect-free phosphorene\nsynthesis on Nickel (Ni) substrate. In addition, the effect of substrate\norientation on the controllable synthesis of possible allotropes has also been\ndescribed. We have shown that blue phosphorene can be grown on Ni (111) and Ni\n(100). While {\\gamma}-Phosphorene, named Navy Phosphorene hereafter, can be\ngrown on Ni (110). Furthermore, we found that the synthesis goes through\nphosphorus pentamers (P5) to phosphorene; P5 is a vital precursor for\nphosphorene synthesis. Moreover, we confirm the high accuracy of the P-Ni, and\nP-P potentials and show that the molecular dynamics (M.D.) approach is a\npowerful tool to simulate the 2D materials synthesis in the vapor phase. This\nwork provides a solid reference to understand and control the synthesis of\nlarge-area single-crystalline monolayer phosphorene.",
        "positive": "Mixed system $Cs_3Cu_3Cl_{8-x}Br_xOH$ with weakly connected Cu-triangles: To study the relationship between the properties of low-dimensional spin\nsystems with weakly coupled Cu-triangles and their crystal structure, single\ncrystals of $Cs_3Cu_3Cl_8OH$ (1) and the new $Cs_3Cu_3Cl_{7.6}Br_{0.4}OH$ (2)\nwere grown. Both compounds are isostructural and crystallize in a monoclinic\nstructure with space group $P2_1/c$. The magnetic susceptibility of (1) shows a\nmaximum at $2.23 K$ and of (2) at $2.70 K$, which are attributed to\nantiferromagnetic phase transitions. Furthermore, the magnetization along the\n$b$-axis at $1.9 K$ for both compounds shows a spin-flop transition into a new\nantiferromagnetic phase. This transition occurs at $0.61 T$ for (1) and at $2.0\nT$ for (2). The antiferromagnetic order can be suppressed by a magnetic field\n$B_{C1}= 1.1 T$ for (1) and $B_{C2}= 1.2 T$ for (2). First single crystal\nneutron diffraction measured on (1) at different temperatures reveals the\nmagnetic signal on the top of the nuclear reflection at (-1 0 0). Its magnetic\nordering temperature was found to be at $T_{N1}= 2.12(3) K$."
    },
    {
        "anchor": "Spin Pumping and Inverse Spin Hall Effect in Germanium: We have measured the inverse spin Hall effect (ISHE) in \\textit{n}-Ge at room\ntemperature. The spin current in germanium was generated by spin pumping from a\nCoFeB/MgO magnetic tunnel junction in order to prevent the impedance mismatch\nissue. A clear electromotive force was measured in Ge at the ferromagnetic\nresonance of CoFeB. The same study was then carried out on several test\nsamples, in particular we have investigated the influence of the MgO tunnel\nbarrier and sample annealing on the ISHE signal. First, the reference CoFeB/MgO\nbilayer grown on SiO$_{2}$ exhibits a clear electromotive force due to\nanisotropic magnetoresistance and anomalous Hall effect which is dominated by\nan asymmetric contribution with respect to the resonance field. We also found\nthat the MgO tunnel barrier is essential to observe ISHE in Ge and that sample\nannealing systematically lead to an increase of the signal. We propose a\ntheoretical model based on the presence of localized states at the interface\nbetween the MgO tunnel barrier and Ge to account for these observations.\nFinally, all of our results are fully consistent with the observation of ISHE\nin heavily doped $n$-Ge and we could estimate the spin Hall angle at room\ntemperature to be $\\approx$0.001.",
        "positive": "Screw-Dislocation-Driven Growth of Two-Dimensional Few-Layer and\n  Pyramid-Like WSe2 by Sulfur-Assisted Chemical Vapor Deposition: Two-dimensional (2D) layered tungsten diselenides (WSe2) material has\nrecently drawn a lot of attention due to its unique optoelectronic properties\nand ambipolar transport behavior. However, direct chemical vapor deposition\n(CVD) synthesis of 2D WSe2 is not as straightforward as other 2D materials due\nto the low reactivity between reactants in WSe2 synthesis. In addition, the\ngrowth mechanism of WSe2 in such CVD process remains unclear. Here we report\nthe observation of a screw-dislocation-driven (SDD) spiral growth of 2D WSe2\nflakes and pyramid-like structures using a sulfur-assisted CVD method.\nFew-layer and pyramid-like WSe2 flakes instead of monolayer were synthesized by\nintroducing a small amount of sulfur as a reducer to help the selenization of\nWO3, which is the precursor of tungsten. Clear observations of steps, helical\nfringes, and herring-bone contours under atomic force microscope\ncharacterization reveal the existence of screw dislocations in the as-grown\nWSe2. The generation and propagation mechanisms of screw dislocations during\nthe growth of WSe2 were discussed. Back-gated field-effect transistors were\nmade on these 2D WSe2 materials, which show on/off current ratios of 106 and\nmobility up to 44 cm2/Vs."
    },
    {
        "anchor": "NMR study of native defects in PbSe: While each atom species in PbSe corresponds to a single crystallographic site\nand transport measurements reveal a single carrier density, $^{207}$Pb NMR\nreveals a more complicated picture than previously thought comprising three\ndiscrete homogeneous carrier components, each associated with $n$- or $p$-type\ncarrier fractions. The origins of these fractions are discussed in terms of\nelectronic heterogeneity of the native semiconductor. The interaction mechanism\nbetween nuclear spins and lattice vibrations via fluctuating spin-rotation\ninteraction, applicable to heavy spin-1/2 nuclei [Phys. Rev. B 74, 214420\n(2006)], does not hold. Instead, a higher-order temperature dependence\ndominates the relaxation pathway. Shallow acceptor states and deep level\ndefects in the midgap explain the complex temperature dependence of the direct\nband gap.",
        "positive": "Template assisted self-assembly of individual and clusters of magnetic\n  nanoparticles: The deliberate control over the spatial arrangement of nanostructures is the\ndesired goal for many applications as e.g. in data storage, plasmonics or\nsensor arrays. Here we present a novel method to assist the self-assembly\nprocess of magnetic nanoparticles. The method makes use of nanostructured\naluminum templates obtained after anodization of aluminum disks and the\nsubsequent growth and removal of the newly formed alumina layer, resulting in a\nregular honeycomb type array of hexagonally shaped valleys. The iron oxide\nnanoparticles, 20 nm in diameter, are spin coated onto the nanostructured\ntemplates. Depending on the size, each hexagon site can host up to 30\nnanoparticles. These nanoparticles form clusters of different arrangements\nwithin the valleys, such as collars, chains, and hexagonally closed islands.\nUltimately, it is possible to isolate individual nanoparticles. The strengths\nof magnetic interaction between particles in a cluster is probed using the\nmemory effect known from the coupled state in superspin glass systems."
    },
    {
        "anchor": "Intriguing magnetism of Fe monolayers on hexagonal transition-metal\n  surfaces: Using first-principles calculations, we demonstrate that an Fe monolayer can\nassume very different magnetic phases on hexagonal hcp (0001) and fcc (111)\nsurfaces of 4d- and 5d-transition metals. Due to the substrates' d-band\nfilling, the nearest-neighbor exchange coupling of Fe changes gradually from\nantiferromagnetic (AFM) for Fe films on Tc, Re, Ru and Os to ferromagnetic on\nRh, Ir, Pd, and Pt. In combination with the topological frustration on the\ntriangular lattice of these surfaces the AFM coupling results in a 120-degree\nNeel structure for Fe on Re and Ru and an unexpected double-row-wise AFM\nstructure on Rh, which is a superposition of a left- and right-rotating\n90-degree spin spiral.",
        "positive": "Study of pnictides for photovoltaic applications: For the transition into a sustainable mode of energy usage, it is important\nto develop photovoltaic materials that exhibit better solar-to-electricity\nconversion efficiencies, a direct optimal band gap, and made of non-toxic,\nearth abundant elements compared to the state-of-the-art silicon photovoltaics.\nHere, we explore the non-redox-active pnictide chemical space, including binary\nA$_3$B$_2$, ternary AA'$_2$B$_2$, and quaternary AA'A\"B$_2$ compounds (A, A',\nA\" = Ca, Sr, or Zn; B = N or P), as candidate beyond-Si photovoltaics using\ndensity functional theory calculations. Specifically, we evaluate the ground\nstate configurations, band gaps, and 0 K thermodynamic stability for all 20\npnictide compositions considered, besides computing the formation energy of\ncation vacancies, anion vacancies, and cation anti-sites in a subset of\ncandidate compounds. Importantly, we identify SrZn$_2$N$_2$, SrZn$_2$P$_2$, and\nCaZn$_2$P$_2$ to be promising candidates, exhibiting optimal (1.1-1.5 eV)\nhybrid-functional-calculated band gaps, stability at 0 K, and high resistance\nto point defects (formation energies $>$1 eV), while other possible candidates\ninclude ZnCa$_2$N$_2$ and ZnSr$_2$N$_2$, which may be susceptible to N-vacancy\nformation. We hope that our study will contribute to the practical development\nof pnictide semiconductors as beyond-silicon light absorbers."
    },
    {
        "anchor": "Anomalous Hall effect and current spin polarization in Co$_2$FeX (X =\n  Al, Ga, In, Si, Ge, and Sn) Heusler compounds: A systematic {\\it ab initio}\n  study: In this paper, we perform a systematic {\\it ab initio} study of two principal\nspin-related phenomena, namely, anomalous Hall effect and current spin\npolarization, in Co$_2$Fe-based Heusler compounds Co$_2$FeX (X = Al, Ga, In,\nSi, Ge, Sn) within the generalized gradient approximation (GGA). The accurate\nfull-potential linearized augmented plane-wave method is used. We find that the\nspin-polarization of the longitudinal current ($P^L$) in Co$_2$FeX (X = Al, Ga,\nIn, Al$_{0.5}$Si$_{0.5}$ and Sn) is $\\sim$100 \\% even though that of the\nelectronic states at the Fermi level ($P^D$) is not. Further, the other\ncompounds also have a high current spin polarization with $P^L > 85$ \\%. This\nindicates that all the Co$_2$FeX compounds considered are promising for\nspin-transport devices. Interestingly, $P^D$ is negative in Co$_2$FeX (X = Si,\nGe and Sn), differing in sign from the $P^L$ as well as that from the transport\nexperiments. Secondly, the calculated anomalous Hall conductivities (AHCs) are\nmoderate, being within 200 S/cm, and agree well with the available experiments\non highly L2$_1$ ordered Co$_2$FeSi specimen although they differ significantly\nfrom the reported experiments on other compounds where the B2 antisite\ndisorders were present. Surprisingly, the AHC in Co$_2$FeSi decreases and then\nchanges sign when Si is replaced by Ge and finally by Sn. Third, the calculated\ntotal magnetic moments agree well with the corresponding experimental ones in\nall the studied compounds except Co$_2$FeSi where a difference of 0.3\n$\\mu_B$/f.u. exists. We also perform the GGA plus on-site Coulomb interaction\n$U$ calculations in the GGA+$U$ scheme. We find that including the $U$ affects\nthe calculated total magnetic moment, spin polarization and AHC significantly,\nand in most cases, results in a disagreement with the available experimental\nresults.",
        "positive": "Robust model benchmarking and bias-imbalance in data-driven materials\n  science: a case study on MODNet: As the number of novel data-driven approaches to material science continues\nto grow, it is crucial to perform consistent quality, reliability and\napplicability assessments of model performance. In this paper, we benchmark the\nMaterials Optimal Descriptor Network (MODNet) method and architecture against\nthe recently released MatBench v0.1, a curated test suite of materials\ndatasets. MODNet is shown to outperform current leaders on 6 of the 13 tasks,\nwhilst closely matching the current leaders on a further 2 tasks; MODNet\nperforms particularly well when the number of samples is below 10,000.\nAttention is paid to two topics of concern when benchmarking models. First, we\nencourage the reporting of a more diverse set of metrics as it leads to a more\ncomprehensive and holistic comparison of model performance. Second, an equally\nimportant task is the uncertainty assessment of a model towards a target\ndomain. Significant variations in validation errors can be observed, depending\non the imbalance and bias in the training set (i.e., similarity between\ntraining and application space). By using an ensemble MODNet model, confidence\nintervals can be built and the uncertainty on individual predictions can be\nquantified. Imbalance and bias issues are often overlooked, and yet are\nimportant for successful real-world applications of machine learning in\nmaterials science and condensed matter."
    },
    {
        "anchor": "Multiple Charge Density Wave States at the Surface of TbTe$_3$: We studied TbTe$_{3}$ using scanning tunneling microscopy (STM) in the\ntemperature range of 298 - 355 K. As seen in previous STM measurements on\nRTe$_{3}$ compounds, our measurements detect a unidirectional charge density\nwave state (CDW) in the surface Te-layer with a wavevector consistent with that\nof the bulk, q$_{cdw}$ = 0.30 $\\pm$ 0.01c$^{*}$. However, unlike previous STM\nmeasurements, and differing from measurements probing the bulk, we detect two\nperpendicular orientations for the unidirectional CDWs with no directional\npreference for the in-plane crystal axes (a- or c-axis) and no noticeable\ndifference in wavevector magnitude. In addition, we find regions in which the\nbidirectional CDW states coexist. We propose that observation of two CDW states\nindicates a decoupling of the surface Te-layer from the rare-earth block layer\nbelow, and that strain variations in the Te surface layer drive the local CDW\ndirection to the specific unidirectional or, in rare occurrences, bidirectional\nCDW orders observed. This indicates that similar driving mechanisms for CDW\nformation in the bulk, where anisotropic lattice strain energy is important,\nare at play at the surface. In our bias-dependent measurements, we find no\ncontrast inversion for the CDW state between occupied and empty states. This\nfinding differs from other quasi 2-dimensional materials containing a hidden\n1-dimensional character which leads to a favorable Fermi surface nesting\nscenario. Our temperature-dependent measurements provide evidence for localized\nCDW formation above the bulk transition temperature, T$_{cdw}$.",
        "positive": "Thickness Estimation of the Si Thin Films: a Simulation Study: We propose a theoretical study for Si thin film thickness measurement that is\nbased on incident low energy electron beam on the film and counting the\ntransmitted/incident electron fraction. It estimates the thin film thickness\ndistribution from a exponential relation which obtained from counting the\nfraction of transmitted/incident electron at different thicknesses. By using\nthis obtained equation, it is possible to estimate unknown thickness of the Si\nthin film. In order to calculate the Si thin film thickness estimation, the\nenergy of the incident electron beams is varied from 6-12 keV, while the\nthickness of the Si film is varied between 100-400 nm. The most significant\nfeature of this method is that no expensive instruments are required. As\nanticipated, the proposed method shows that there is a relationship between\nfilm thickness and incident beam energy, which by using this relationship, we\ncan find unknown film thickness in 1-D and 2-D conditions. Other advantages\ninclude wide measurement range, no calibration need and simple method.\nAdditionally, an investigation by different beam energies helps to avoid\nartefact from this method. All calculations were done by CASINO numerical\nsimulation package."
    },
    {
        "anchor": "Interface exchange processes in LaAlO$_3$/SrTiO$_3$ induced by oxygen\n  vacancies: Understanding the role of defects in oxide heterostructures is crucial for\nfuture materials control and functionalization. We hence study the impact of\noxygen vacancies (OVs) at variable concentrations on orbital- and spin exchange\nin the LaAlO$_3$/SrTiO$_3$ interface by first principles many-body theory and\nreal-space model-Hamiltonian techniques. Intricate interplay between Hubbard\n$U$ and Hund's coupling $J_{\\rm H}$ for OV-induced correlated states is\ndemonstrated. Orbital polarization towards an effective $e_g$ state with\npredominant local antiferromagnetic alignment on Ti sites near OVs is\ncontrasted with $t_{2g}(xy)$ states with ferromagnetic tendencies in the\ndefect-free regions. Different magnetic phases are identified, giving rise to\ndistinct net-moment behavior at low and high OV concentrations. This provides a\ntheoretical basis for prospective tailored magnetism by defect manipulation in\noxide interfaces.",
        "positive": "Dzyaloshinskii-Moriya interaction in Nd$_{2}$Fe$_{14}$B as the origin of\n  spin reorientation and rotating magnetocaloric effect: The mechanism of spin reorientation in Nd$_{2}$Fe$_{14}$B, which is a host\ncrystal of a well-known neodymium permanent magnet, is studied by combining\nfirst-principles calculations and Monte Carlo simulations. The spin\nreorientation is thought to be derived from crystal field effects and gets less\nattention because of the undesirable property for hard magnet application.\nDzyaloshinskii-Moriya interactions are usually less attractive or often ignored\nin rare-earth bulk systems, including permanent magnets such as\nNd$_{2}$Fe$_{14}$B since people believe that the magnetic anisotropy is more\ndominant than the Dzyaloshinskii-Moriya interactions. However, in this study,\nwe have found, for the first time, that the spin reorientation in\nNd$_{2}$Fe$_{14}$B is attributed to Dzyaloshinskii-Moriya interactions. We have\nfound, furthermore, the spin reorientation in Nd$_{2}$Fe$_{14}$B yields a great\nstage of rotating magnetocaloric effect at practical application level. We have\nfound that the Dzyaloshinskii-Moriya interactions definitely contributes to the\nphysical properties as a non-negligible effect in magnetic materials."
    },
    {
        "anchor": "Nonadiabatic generation of coherent phonons: The time-dependent density functional theory (TDDFT) is the leading\ncomputationally feasible theory to treat excitations by strong electromagnetic\nfields. Here the theory is applied to coherent optical phonon generation\nproduced by intense laser pulses. We examine the process in the crystalline\nsemimetal antimony (Sb), where nonadiabatic coupling is very important. This\nmaterial is of particular interest because it exhibits strong phonon coupling\nand optical phonons of different symmetries can be observed. The TDDFT is able\nto account for a number of qualitative features of the observed coherent\nphonons, despite its unsatisfactory performance on reproducing the observed\ndielectric functions of Sb. A simple dielectric model for nonadiabatic coherent\nphonon generation is also examined and compared with the TDDFT calculations.",
        "positive": "Unified approach to polarons and phonon-induced band structure\n  renormalization: Ab initio calculations of the phonon-induced band structure renormalization\nare currently based on the perturbative Allen-Heine theory and its many-body\ngeneralizations. These approaches are unsuitable to describe materials where\nelectrons form localized polarons. Here, we develop a self-consistent,\nmany-body Green's function theory of band structure renormalization that\nincorporates localization and self-trapping. We show that the present approach\nreduces to the Allen-Heine theory in the weak-coupling limit, and to total\nenergy calculations of self-trapped polarons in the strong-coupling limit. To\ndemonstrate this methodology, we reproduce the path-integral results of Feynman\nand diagrammatic Monte Carlo calculations for the Fr\\\"ohlich model at all\ncouplings, and we calculate the zero point renormalization of the band gap of\nan ionic insulator including polaronic effects."
    },
    {
        "anchor": "Thermally-activated charge reversibility of gallium vacancies in GaAs: The dominant charge state for the Ga vacancy in GaAs has been the subject of\na long debate, with experiments proposing $-$1, $-$2 or $-$3 as the best\nanswer. We revisit this problem using {\\it ab initio} calculations to compute\nthe effects of temperature on the Gibbs free energy of formation, and we find\nthat the thermal dependence of the Fermi level and of the ionization levels\nlead to a reversal of the preferred charge state as the temperature increases.\nCalculating the concentrations of gallium vacancies based on these results, we\nreproduce two conflicting experimental measurements, showing that these can be\nunderstood from a single set of coherent LDA results when thermal effects are\nincluded.",
        "positive": "Structure and magnetic properties of epitaxial CaFe2O4 thin films: CaFe2O4 is a highly anisotropic antiferromagnet reported to display two spin\narrangements with up-up-down-down (phase A) and up-down-up-down (phase B)\nconfigurations. The relative stability of these phases is ruled by the\ncompeting ferromagnetic and antiferromagnetic interactions between Fe3+ spins\narranged in two different environments, but a complete understanding of the\nmagnetic structure of this material does not exist yet. In this study we\ninvestigate epitaxial CaFe2O4 thin films grown on TiO2 (110) substrates by\nmeans of Pulsed Laser Deposition (PLD). Structural characterization reveals the\ncoexistence of two out-of-plane crystal orientations and the formation of three\nin-plane oriented domains. The magnetic properties of the films, investigated\nmacroscopically as well as locally, including highly sensitive Mossbauer\nspectroscopy, reveal the presence of just one order parameter showing\nlong-range ordering below T = 185 K and the critical nature of the transition.\nIn addition, a non-zero in-plane magnetization is found, consistent with the\npresence of uncompensated spins at phase or domain boundaries, as proposed for\nbulk samples."
    },
    {
        "anchor": "Octahedral tilting induced ferroelectricity in the ASnO${_3}$/BSnO${_3}$\n  superlattice: The effect of the octahedral tilting of ASnO3 (A = Ca, Sr, Ba) parent\ncompound and bi-color ASnO3/BSnO3 superlattice (A, B = Ca, Sr, Ba) was\npredicted from density-functional theory. In the ASnO3 parent compound, the\nstructural phase transition as a function of the A-site cation size was\ncorrelated with the magnitude of the two octahedral tilting modes (a-a-c0\ntilting and a0a0c+ tilting). The magnitude of the octahedral tilting modes in\nthe superlattices was analyzed quantitatively and found to be associated with\nthat of the constituent parent materials. The ASnO3/BSnO3 superlattices showed\nhybrid improper ferroelectricity resulting from the coupling of two octahedral\ntilting modes (a-a-c0 tilting and a0a0c+ tilting), which are also responsible\nfor the structural phase transition from a tetragonal to orthorhombic phase.\nThe ferroelectricity due to A-site mirror symmetry breaking is a secondary\norder parameter for an orthorhombic phase transition in the bi-color\nsuperlattice and is related to the {\\Gamma}5- symmetry mode. The coupling\nbetween the tilting modes and ferroelectric mode in the bi-color superlattice\nof ASnO3/BSnO3 was analyzed by group theory and symmetry mode analysis.",
        "positive": "Specific heat, thermal conductivity, and magnetic susceptibility of\n  cyanate ester resins --- An alternative to commonly used epoxy resins: In low temperature experiments, resins have many applications as glues or\nthermal and electrical insulators. Cyanate ester resins (CEs) are a\nhigh-temperature compatible thermoset resin whose glass-transition temperature\n$T_g$ is ~300 $^\\circ$C. Recently, we found that CEs also withstand low\ntemperatures without microcracking by measuring $^4$He permeability. Here, we\nmeasured specific heat C, thermal conductivity \\kappa, and magnetic\nsusceptibility $\\chi$ of different kinds of CEs in the wide temperature range\nfrom room temperature to 0.5 K for C and 2 K for other two. The thermal\nproperties, C and \\kappa, of different kinds of CEs are surprisingly coincident\nwith each other. We discuss chemical structures and crystallinity of CEs and\ntheir blends based on the measured thermal properties. Compared to Stycast\n1266, a commonly-used epoxy resin in low temperature experiments, C of CEs is\nlarger by a factor of 3 (<= 30 K), \\kappa is lower by a factor of 4 (<= 10 K),\nindicating the small thermal diffusivity. The \\chi values are as small as\nStycast 1266, indicative of their high purity. Our results show that cyanate\nesters are a new option for cryogenic resins with thermal insulative properties\nin/for low temperature experiments."
    },
    {
        "anchor": "Fermi arcs and pseudogap emerging from dimensional crossover at the\n  Fermi surface in La$_{2-x}$Sr$_x$CuO$_4$: The doping mechanism and realistic Fermi surface (FS) evolution of\nLa$_{2-x}$Sr$_x$CuO$_4$ (LSCO) are modelled within an extensive ab-initio\nframework including advanced band-unfolding techniques. We show that ordinary\nKohn-Sham DFT+U can reproduce the observed metal-insulator transition, when not\nrestricted to the paramagnetic solution space. Arcs are self-doped by orbital\ncharge transfer within the Cu-O planes, while the introduced Sr charge is\nstrongly localized. Arc protection and the inadequacy of the rigid-band picture\nare consequences of a rapid change in orbital symmetry at the Fermi energy: the\nmaterial undergoes a dimensional crossover along the Fermi surface, between the\nnodal (2D) and antinodal (3D) regions. In LSCO, this crossover accounts for FS\narcs, the antinodal pseudogap, and insulating behavior in $c$-axis\nconductivity, all ubiquitous phenomena in high-T$_c$ cuprates. Ligand Coulomb\nintegrals involving out-of-plane sites are principally responsible for the most\nstriking effects observed by ARPES in LSCO.",
        "positive": "Machine Learning for First Principles Calculations of Material\n  Properties for Ferromagnetic Materials: The investigation of finite temperature properties using Monte-Carlo (MC)\nmethods requires a large number of evaluations of the system's Hamiltonian to\nsample the phase space needed to obtain physical observables as function of\ntemperature. DFT calculations can provide accurate evaluations of the energies,\nbut they are too computationally expensive for routine simulations. To\ncircumvent this problem, machine-learning (ML) based surrogate models have been\ndeveloped and implemented on high-performance computing (HPC) architectures. In\nthis paper, we describe two ML methods (linear mixing model and HydraGNN) as\nsurrogates for first principles density functional theory (DFT) calculations\nwith classical MC simulations. These two surrogate models are used to learn the\ndependence of target physical properties from complex compositions and\ninteractions of their constituents. We present the predictive performance of\nthese two surrogate models with respect to their complexity while avoiding the\ndanger of overfitting the model. An important aspect of our approach is the\nperiodic retraining with newly generated first principles data based on the\nprogressive exploration of the system's phase space by the MC simulation. The\nnumerical results show that HydraGNN model attains superior predictive\nperformance compared to the linear mixing model for magnetic alloy materials."
    },
    {
        "anchor": "Mechanical control of physical properties in the van der Waals\n  ferromagnet Cr2Ge2Te6 via application of electric current: Cr2Ge2Te6 is a van der Waals ferromagnet with a Curie temperature at 66 K.\nHere we report a swift change in the magnetic ground state upon application of\nsmall DC electric current, a giant yet anisotropic magnetoelectric effect, and\na sharp, lattice-driven quantum switching manifested in the I-V characteristic\nof the bulk single-crystal Cr2Ge2Te6. At the heart of these observed phenomena\nis a newly uncovered, strongly anisotropic magnetoelastic coupling that enables\nstrongly anisotropic responses of the lattice to application of electric\ncurrent and/or magnetic field, thus the exotic phenomena in Cr2Ge2Te6. Such a\nrare mechanical tunability in the magnetic semiconductors promises tantalizing\nprospects for unique functional materials and devices.",
        "positive": "Suppressing chemical corrosions of lithium metal anodes: The lithium (Li) metal anode is essential for next generation high energy\ndensity rechargeable Li metal batteries. Although extensive studies have been\nperformed to prolong the cycle life of Li metal batteries, the calendar life,\nwhich associates with chemical corrosion of Li metal in liquid electrolytes,\nhas not been quantitatively understood. Here, by combing the Titration Gas\nChromatography (TGC) method and Cryogenic Focused Ion Beam (Cryo-FIB), we\nestablished a quantitative relationship between the chemical corrosion rate and\nelectrochemically deposited Li morphology in various liquid electrolyte\nsystems. We identified that the corrosion rate is dominated by the porosity of\nthe deposited Li. The larger the porosity of deposited Li has, the faster the\ncorrosion rate will be. We further proposed strategies to mitigate the chemical\ncorrosion on Li thus to extend the calendar life of Li metal batteries. By\nstrictly controlling the stacking pressure during Li plating, Li deposits with\nultra-low porosity can be achieved, suppressing the corrosion rate to 0.08% per\nday compared with 1.71% per day of the high-porosity Li."
    },
    {
        "anchor": "Acoustoelectric Study of Interface Trapping Defects in GaAs Epitaxial\n  Strucrures: A new acousto-electrical method making use of transient transverse\nacoustoelectric voltage (TAV) to study solid state structures is reported. This\nvoltage arises after a surface acoustic wave (SAW) generating the signal is\nswitched off. Related measurements consist in detecting the shape of transient\nvoltage and its spectral and temperature dependence. Both theory and experiment\nshow that this method is an effective tool to characterize trapping centers in\nthe bulk as well as at surfaces or interfaces of epitaxial semiconductor\nstructures.",
        "positive": "Data Mining for better material synthesis: the case of pulsed laser\n  deposition of complex oxides: The pursuit of more advanced electronics, finding solutions to energy needs,\nand tackling a wealth of social issues often hinges upon the discovery and\noptimization of new functional materials that enable disruptive technologies or\napplications. However, the discovery rate of these materials is alarmingly low.\nMuch of the information that could drive this rate higher is scattered across\ntens of thousands of papers in the extant literature published over several\ndecades, and almost all of it is not collated and thus cannot be used in its\nentirety. Many of these limitations can be circumvented if the experimentalist\nhas access to systematized collections of prior experimental procedures and\nresults that can be analyzed and built upon. Here, we investigate the\nproperty-processing relationship during growth of oxide films by pulsed laser\ndeposition. To do so, we develop an enabling software tool to (1) mine the\nliterature of relevant papers for synthesis parameters and functional\nproperties of previously studied materials, (2) enhance the accuracy of this\nmining through crowd sourcing approaches, (3) create a searchable repository\nthat will be a community-wide resource enabling material scientists to leverage\nthis information, and (4) provide through the Jupyter notebook platform, simple\nmachine-learning-based analysis to learn the complex interactions between\ngrowth parameters and functional properties (all data and codes available on\nhttps://github.com/ORNL-DataMatls). The results allow visualization of growth\nwindows, trends and outliers, and which can serve as a template for analyzing\nthe distribution of growth conditions, provide starting points for related\ncompounds and act as feedback for first-principles calculations. Such tools\nwill comprise an integral part of the materials design schema in the coming\ndecade."
    },
    {
        "anchor": "Broadband Optical Detection using the Spin Seebeck Effect: The generation, control, and detection of spin currents in solid-state\ndevices are critical for Joule-heating minimization, spin-based computation,\nand electrical energy generation from thermal gradients. Although incorporation\nof spin functionality into technologically important architectures is still in\nits infancy, advantages over all-electric devices are increasingly becoming\nclear. Here, we utilize the spin Seebeck effect (SSE) in Pt/Y3Fe5O12 devices to\ndetect light from 390 to 2200 nm. We find the device responsivity is remarkably\nflat across this technologically important wavelength range, closely following\nthe Pt absorption coefficient. As expected from a SSE-generation mechanism, we\nobserve that the photovoltage and Pt heating dynamics are in strong agreement.\nTo precisely determine the optically created thermal gradient produced from a\npoint-like heat source, we introduce a field-modulation method for measuring\nthe SSE. Our results show broadband optical detection can be performed with\ndevices based solely on spin current generation and detection.",
        "positive": "Proposal for measuring magnetism with patterned apertures: We propose a magnetic measurement method utilizing a patterned post-sample\naperture in a transmission electron microscope. While utilizing electron\nmagnetic circular dichroism, the method circumvents previous needs to shape the\nelectron probe to an electron vortex beam or astigmatic beam. The method can be\nimplemented in standard scanning transmission electron microscopes by replacing\nthe spectrometer entrance aperture with a specially shaped aperture, hereafter\ncalled ventilator aperture. The proposed setup is expected to work across the\nwhole range of beam sizes -- from wide parallel beams down to atomic resolution\nmagnetic spectrum imaging."
    },
    {
        "anchor": "Optical studies of carrier and phonon dynamics in Ga_{1-x}Mn_{x}As: We present a time-resolved optical study of the dynamics of carriers and\nphonons in Ga_{1-x}Mn_{x}As layers for a series of Mn and hole concentrations.\nWhile band filling is the dominant effect in transient optical absorption in\nlow-temperature-grown (LT) GaAs, band gap renormalization effects become\nimportant with increasing Mn concentration in Ga_{1-x}Mn_{x}As, as inferred\nfrom the sign of the absorption change. We also report direct observation on\nlattice vibrations in Ga1-xMnxAs layers via reflective electro-optic sampling\ntechnique. The data show increasingly fast dephasing of LO phonon oscillations\nfor samples with increasing Mn and hole concentration, which can be understood\nin term of phonon scattering by the holes.",
        "positive": "Atomically-Precise, Custom-Design Origami Graphene Nanostructures: The construction of atomically-precise carbon nanostructures holds promise\nfor developing novel materials for scientific study and nanotechnology\napplications. Here we show that graphene origami is an efficient way to convert\ngraphene into atomically-precise, complex, and novel nanostructures. By\nscanning-tunneling-microscope manipulation at low temperature, we repeatedly\nfold and unfold graphene nanoislands (GNIs) along arbitrarily chosen direction.\nA bilayer graphene stack featuring a tunable twist angle and a tubular edge\nconnection between the layers are formed. Folding single-crystal GNIs creates\ntubular edges with specified chirality and one-dimensional electronic features\nsimilar to those of carbon nanotubes, while folding bi-crystal GNIs creates\nwell-defined intramolecular junctions. Both origami structural models and\nelectronic band structures were computed to complement analysis of the\nexperimental results. The present atomically-precise graphene origami provides\na platform for constructing novel carbon nanostructures with engineered quantum\nproperties and ultimately quantum machines."
    },
    {
        "anchor": "What Information is Necessary and Sufficient to Predict Materials\n  Properties using Machine Learning?: Conventional wisdom of materials modelling stipulates that both chemical\ncomposition and crystal structure are integral in the prediction of physical\nproperties. However, recent developments challenge this by reporting accurate\nproperty-prediction machine learning (ML) frameworks using composition alone\nwithout knowledge of the local atomic environments or long-range order. To\nprobe this behavior, we conduct a systematic comparison of supervised ML models\nbuilt on composition only vs. composition plus structure features. Similar\nperformance for property prediction is found using both models for compounds\nclose to the thermodynamic convex hull. We hypothesize that composition embeds\nstructural information of ground-state structures in support of\ncomposition-centric models for property prediction and inverse design of stable\ncompounds.",
        "positive": "Unexpected Scaling of the Performance of Carbon Nanotube Transistors: We show that carbon nanotube transistors exhibit scaling that is\nqualitatively different than conventional transistors. The performance depends\nin an unexpected way on both the thickness and the dielectric constant of the\ngate oxide. Experimental measurements and theoretical calculations provide a\nconsistent understanding of the scaling, which reflects the very different\ndevice physics of a Schottky barrier transistor with a quasi-one-dimensional\nchannel contacting a sharp edge. A simple analytic model gives explicit scaling\nexpressions for key device parameters such as subthreshold slope, turn-on\nvoltage, and transconductance."
    },
    {
        "anchor": "Non-invasive digital etching of van der Waals semiconductors: The capability to finely tailor material thickness with simultaneous atomic\nprecision and non-invasivity would be useful for constructing quantum platforms\nand post-Moore microelectronics. However, it remains challenging to attain\nsynchronized controls over tailoring selectivity and precision. Here we report\na protocol that allows for non-invasive and atomically digital etching of van\nder Waals transition-metal dichalcogenides through selective alloying via\nlow-temperature thermal diffusion and subsequent wet etching. The mechanism of\nselective alloying between sacrifice metal atoms and defective or pristine\ndichalcogenides is analyzed with high-resolution scanning transmission electron\nmicroscopy. Also, the non-invasive nature and atomic level precision of our\netching technique are corroborated by consistent spectral, crystallographic and\nelectrical characterization measurements. The low-temperature charge mobility\nof as-etched MoS$_2$ reaches up to $1200\\,$cm$^{2}\\cdot$V$^{-1}\\cdot$s$^{-1}$,\ncomparable to that of exfoliated pristine counterparts. The entire protocol\nrepresents a highly precise and non-invasive tailoring route for material\nmanipulation.",
        "positive": "Interaction of water with nitrogen-doped graphene: We have studied the interaction of water and graphene doped with nitrogen in\ndifferent configurations, namely, graphitic and pyridinic nitrogen, by means of\nthe van der Waals density functional. We found that the local nitrogen\nconfiguration plays a key role in determining the stable water configuration,\nwhile the dispersion force is responsible for the water adsorption. With the\ngraphitic nitrogen, water prefers to orient with its oxygen toward the surface,\nwhereas for the pyridinic nitrogen it prefers to orient with its hydrogens\ntoward the surface, because nitrogen is positively and negatively charged for\nthe former and the latter, respectively. Our results have great implications\nfor the modeling of the interface between water and nitrogen-doped graphitic\nsystems."
    },
    {
        "anchor": "Interacting quantum rotors in oxygen-doped germanium: We investigate the interaction effect between oxygen impurities in\ncrystalline germanium on the basis of a quantum rotor model. The dipolar\ninteraction of nearby oxygen impurities engenders non-trivial low-lying\nexcitations, giving rise to anomalous behaviors for oxygen-doped germanium\n(Ge:O) below a few degrees Kelvin. In particular, it is theoretically predicted\nthat Ge:O samples with oxygen-concentration of 10$^{17-18}$cm$^{-3}$ show (i)\npower-law specific heats below 0.1 K, and (ii) a peculiar hump in dielectric\nsusceptibilities around 1 K. We present an interpretation for the power-law\nspecific heats, which is based on the picture of local double-well potentials\nrandomly distributed in Ge:O samples.",
        "positive": "Short Communication: Stable DRIE-patterned SiO2/Si3N4 electrets for\n  electret-based vibration energy harvesters: This paper is about a new manufacturing process aimed at developing stable\nSiO2/Si3N4 patterned electrets using a Deep Reactive Ion Etching (DRIE) step\nfor an application in electret Vibration Energy Harvesters (VEH). Electrets\ncharged by a positive corona discharge show excellent stability with high\nsurface charge density that can reach 5mC/m^{2} on 1.1\\mum-thick layers, even\nwith fine patterning (down to 25\\mum) and harsh temperature conditions (up to\n250{\\deg}C), paving the way to new electret VEH designs and manufacturing\nprocesses."
    },
    {
        "anchor": "First-principles investigation of Sc-III/IV under High Pressure: Using ab initio evolutionary structure prediction method in conjunction with\ndensity functional theory, we performed a systematic investigation on the\nstructural transition of elemental scandium under pressure up to 250 GPa. Our\nprediction successfully reproduced several allotropes which have been reported\nin the previous literature, including the Sc-I, Sc-II and Sc-V. Moreover, we\nobserved a series of energetically degenerate and geometrically similar\nstructures at 110-195 GPa, which are likely to explain the unsolved phases III\nand IV reported by Akahama [Phys. Rev. Lett.,94, 19, 195503, (2005)]. A\ndetailed comparison on powder X-ray diffraction pattern (PXRD) suggested that\nthe Ccca-20 phase may account for the observed Sc-III, while Sc-IV is likely to\nbe explained by a mixture of multiple energetically competing structures. We\nalso used the candidate Sc-III structure as the model system to explore its\nsuperconducting behavior under pressures between 80-130 GPa. The predicted\nsuperconducting transition temperature Tc values are in satisfactory agreement\nwith previous experimental results.",
        "positive": "Theory of Reciprocating Contact for Viscoelastic Solids: A theory of reciprocating contacts for linear viscoelastic materials is\npresented. Results are discussed for the case of a rigid sphere sinusoidally\ndriven in sliding contact with a viscoelastic half-space. Depending on the size\nof the contact, the frequency and amplitude of the reciprocating motion, and on\nthe relaxation time of the viscoelastic body, we establish that the contact\nbehavior may range from the steady-state viscoelastic solution, in which\ntraction forces always oppose the direction of the sliding rigid punch, to a\nmore elaborate trend, never observed before, which is due to the strong\ninteraction between different regions of the path covered during the\nreciprocating motion. Practical implications span a number of applications,\nranging from seismic engineering to biotechnology."
    },
    {
        "anchor": "New CuSO4-related high-temperature polymorph of AgIISO4: Silver(II) compounds exhibit powerful oxidizing properties and strong\nmagnetic superexchange. AgSO4 is a rare fluorine-free salt of Ag(II) which\nfound some application in organic chemistry. Here, we report a discovery of a\nnew AgSO4 polymorph (\\b{eta}). The distinct nature of the two polytypes of\nAgSO4 is established using powder x-ray diffraction, vibrational spectroscopy\nand theoretical calculations. The \\b{eta} polymorph crystallizes in the\nmonoclinic system (P21/n) and shows structural similarities with CuSO4. DFT\ncalculations indicate very small differences in the energy of the two\npolymorphs AgSO4, but the relative stability of the \\b{eta} polymorph should\nincrease with temperature. The monoclinic distortion of the orthorhombic CuSO4\nprototype originates from an unprecedented strong antiferromagnetic interaction\nbetween Ag sites along the unit cell diagonal.",
        "positive": "Multiferroic RMnO3 thin films: Multiferroic materials have received an astonishing attention in the last\ndecades due to expectations that potential coupling between distinct ferroic\norders could inspire new applications and new device concepts. As a result, a\nnew knowledge on coupling mechanisms and materials science has dramatically\nemerged. Multiferroic RMnO3 perovskites are central to this progress providing\na suitable platform to tailor spin-spin and spin-lattice interactions. With\nviews towards applications, development of thin films of multiferroic materials\nhave also progressed enormously and nowadays thin film manganites are available\nwith properties mimicking those of bulk compounds. Here we review achievements\non the growth and characterization of magnetic and ferroelectric properties of\nhexagonal and orthorhombic RMnO3 epitaxial thin films, discuss some challenging\nissues and we suggest some guidelines for future research and developments."
    },
    {
        "anchor": "Variable damping and coherence in a high-density magnon gas: We report on the fast relaxation behavior of a high-density magnon gas\ncreated by a parametric amplification process. The magnon gas is probed using\nthe technique of spin-wave packet recovery by parallel parametric pumping.\nExperimental results show a damping behavior which is in disagreement with both\nthe standard model of exponential decay and with earlier observations of\nnon-linear damping. In particular, the inherent magnon damping is found to\ndepend upon the presence of the parametric pumping field. A phenomenological\nmodel which accounts for the dephasing of the earlier injected magnons is in\ngood agreement with the experimental data.",
        "positive": "(NaCl)_x(KCl)_{y-x}(KBr)_{1-y} single crystals: study of the ac\n  conductivity activation energy: Ac electrical measurements have been reported for alkali halide mixed\ncrystals that were melt grown from NaCl, KCl and KBr starting materials. They\nshowed a nonlinear variation of all the electrical parameters with the bulk\ncomposition. Here, we show that these mixed systems, depending on their major\nconstituent, are classified into three categories in each of which, the\nactivation energy for the ac conductivity increases linearly with B$\\Omega$,\nwhere B is the isothermal bulk modulus and $\\Omega$ the mean volume per atom."
    },
    {
        "anchor": "Demonstration of electron filtering to increase the Seebeck coefficient\n  in ErAs:InGaAs/InGaAlAs superlattices: In this letter, we explore electron filtering as a technique to increase\nSeebeck coefficient and the thermoelectric power factor of heterostructured\nmaterials over that of the bulk. We present a theoretical model in which\nSeebeck coefficient and the power factor can be increased in an InGaAs based\ncomposite material. Experimental measurements of the cross-plane Seebeck\ncoefficient are presented and confirm the importance of the electron filtering\ntechnique to decouple the electrical conductivity and Seebeck coefficient to\nincrease the thermoelectric power factor.",
        "positive": "Geometrical Frustration in Liquid Fe and Fe-Based Metallic Glass: We investigate short rane order in liquid and supercooled liquid Fe and\nFe-based metallic glass using ab-initio simulation methods. We analyze the data\nto quantify the degree of local icosahedral and polytetrahedral order and to\nunderstand the role of alloying in controlling the degree of geometric\nfrustration . Comparing elemental Fe to Cu we find that the degree of\nicosahedral order is greater in Fe than in Cu, possibly because icosahedral\ndisclination line defects are more easily incorporated into BCC environments\nthan FCC. In Fe-based metallic glass-forming alloys (FeB and FeZrB) we find\nthat introducing small concentrations of small B atoms and large Zr atoms\ncontrols the frustration of local icosahedral order."
    },
    {
        "anchor": "Geometrical and electronic structures of tripotassium-doped hydrocarbon\n  superconductors: Density functional calculations: A systemically theoretical study has been presented to explored the crystal\nstructures and electronic characteristics of polycyclic aromatic hydrocarbons\n(PAHs), such as solid phenanthrene, picene, 1,2;8,9-dibenzopentacene, and\n7-phenacenes, since these PAHs exhibited the superconductivity when potassium\ndoping into. For tripotassium-doped phenanthrene and picene, we demonstrate the\nK atomic positions to fit the experimental lattice parameters, and analyze the\ndistinction between the stablest configuration and the fitted experimental one.\nBased on the first-principles calculations, for the first time, we predict the\npossible crystal configurations of pristine and tripotassium-doped\n1,2;8,9-dibenzopentacene and 7-phenacenes, respectively. For these four PAHs,\nthe electronic structures after doping are investigated in details. The results\nshow that the electronic characters near the Fermi level are high sensitive to\nstructure. Because of the change of the benzene rings arrangement, the\n1,2;8,9-dibenzopentacene exhibits visibly different band structures from other\nthree PAHs. In these metallic PAHs, two bands cross the Fermi level which\nresults in the complicated multiband feature of Fermi surfaces. Fascinatingly,\nwe find that the electronic states of potassium contribute to the Fermi\nsurfaces especially for K-3$d$ electrons, which improves a way to understand\nthis superconductivity. As a result, we suggest that the rigid-band picture is\ninvalidated due to the hybridization between K atoms and PAH molecules as well\nas the rearrangement and distortion of PAH molecules.",
        "positive": "Temperature-Modulated Differential Scanning Calorimetry Analysis of\n  High-Temperature Silicate Glasses: Differential scanning calorimetry (DSC) is one of the most versatile probes\nfor silicate glasses, allowing determination of, e.g., transition temperatures\n(glass, crystallization, melting) and the temperature dependence of heat\ncapacity. However, complications arise for glasses featuring overlapping\ntransitions and low sensitivity, e.g., arising from SiO2-rich compositions with\nsmall change in heat capacity during glass transition or the low sensitivity of\nthermocouples at high temperature. These challenges might be overcome using\ntemperature-modulated DSC (TM-DSC), which enables separation of overlapping\nsignals and improved sensitivity at the expense of increased measurement\nduration."
    },
    {
        "anchor": "Influence of distortion on the electronic band structure of CuInSe2: We present a tight-binding calculation of the influence of distorsion on the\nbulk electronic structure of the chalcopyrite CuInSe2. We calculate the ideal\ncase and then the effect of the inclusion of the distortions. We analyze our\nresults in detail and conclude from a comparison with other work that the\ndistortions must be included in the Hamiltonian to get a proper account of the\nelectronic band structure. We use our new Hamiltonian to study the effect that\nboth the tetragonal and the anionic distortion have on the (112) surface\nelectronic band structure. We find this effect non-negligible.",
        "positive": "Dipolar interaction effects in the magnetic and magnetotransport\n  properties of ordered nanoparticle arrays: Assemblies of magnetic nanoparticles exhibit interesting physical properties\narising from the competition of intraparticle dynamics and interparticle\ninteractions. In ordered arrays of magnetic nanoparticles magnetostatic\ninterparticle interactions introduce collective dynamics acting competitively\nto random anisotropy. Basic understanding, characterization and control of\ndipolar interaction effects in arrays of magnetic nanoparticles is an issue of\ncentral importance. To this end, numerical simulation techniques offer an\nindispensable tool. We report on Monte Carlo studies of the magnetic hysteresis\nand spin-dependent transport in thin films formed by ordered arrays of magnetic\nnanoparticles. Emphasis is given to the modifications of the single-particle\nbehavior due to interparticle dipolar interactions as these arise in quantities\nof experimental interest, such as, the magnetization, the susceptibility and\nthe magnetoresistance. We investigate the role of the structural parameters of\nan array (interparticle separation, number of stacked monolayers) and the role\nof the internal structure of the nanoparticles (single phase, core-shell).\nDipolar interactions are responsible for anisotropic magnetic behavior between\nthe in-plane and out-of-plane directions of the sample, which is reflected on\nthe investigated magnetic properties (magnetization, transverse susceptibility\nand magnetoresistance) and the parameters of the array (remanent magnetization,\ncoercive field, and blocking temperature). Our numerical results are compared\nto existing measurements on self-assembled arrays of Fe-based and Co\nnanoparticles is made."
    },
    {
        "anchor": "Generation of broadband THz pulses in organic crystal OH1 at room\n  temperature and 10 K: We studied the effects of cryogenic cooling of a 2-[3-(4-hydroxystyryl)-5,\n5-dimethylcyclohex-2-enylidene] malononitrile (OH1) crystal on the generation\nof broadband THz pulses via collinear optical rectification of 1350 nm\nfemtosecond laser pulses. Cooling of the OH1 crystal from room temperature to\n10 K leads to a ~10% increase of the pump-to-THz energy conversion efficiency\nand a shift of the THz pulse spectra to a higher frequency range. Both effects\nare due the temperature variation of THz absorption and the refractive index of\nthe OH1 crystal. This conclusion has been verified by temperature dependent\nmeasurements of the linear absorption in the THz frequency region.",
        "positive": "Bi-Arrhenius diffusion and surface trapping of $^{8}$Li$^{+}$ in rutile\n  TiO$_2$: We report measurements of the diffusion rate of isolated ion-implanted\n$^{8}$Li$^{+}$ within $\\sim$120 nm of the surface of oriented single-crystal\nrutile TiO$_2$ using a radiotracer technique. The $\\alpha$-particles from the\n$^{8}$Li decay provide a sensitive monitor of the distance from the surface and\nhow the depth profile of $^{8}$Li evolves with time. The main findings are that\nthe implanted Li$^{+}$ diffuses and traps at the (001) surface. The\nT-dependence of the diffusivity is described by a bi-Arrhenius expression with\nactivation energies of 0.3341(21) eV above 200 K, whereas at lower temperatures\nit has a much smaller barrier of 0.0313(15) eV. We consider possible origins\nfor the surface trapping, as well the nature of the low-T barrier."
    },
    {
        "anchor": "Electronic Structure of the Bond Disproportionated Bismuthate\n  Ag$_2$BiO$_3$: We present a comprehensive study on the silver bismuthate Ag$_2$BiO$_3$,\nsynthesized under high-pressure high-temperature conditions, which has been the\nsubject of recent theoretical work on topologically complex electronic states.\nWe present X-ray photoelectron spectroscopy results showing two different\nbismuth states, and X-ray absorption spectroscopy results on the oxygen\n$K$-edge showing holes in the oxygen bands. These results support a bond\ndisproportionated state with holes on the oxygen atoms for Ag$_2$BiO$_3$. We\nestimate a band gap of $\\sim$1.25~eV for Ag$_2$BiO$_3$ from optical\nconductivity measurements, which matches the band gap in density functional\ncalculations of the electronic band structure in the non-symmorphic space group\n$Pnn2$, which supports two inequivalent Bi sites. In our band structure\ncalculations the disproportionated Ag$_2$BiO$_3$ is expected to host Weyl nodal\nchains, one of which is located $\\sim$0.5~eV below the Fermi level.\nFurthermore, we highlight similarities between Ag$_2$BiO$_3$ and the well-known\ndisproportionated bismuthate BaBiO$_3$, including breathing phonon modes with\nsimilar energy. In both compounds hybridization of Bi-$6s$ and O-$2p$ atomic\norbitals is important in shaping the band structure, but in contrast to the\nBa-$5p$ in BaBiO$_3$, the Ag-$4d$ bands in Ag$_2$BiO$_3$ extend up to the Fermi\nlevel.",
        "positive": "Fast domain wall propagation under an optimal field pulse in magnetic\n  nanowires: We investigate field-driven domain wall (DW) propagation in magnetic\nnanowires in the framework of the Landau-Lifshitz-Gilbert equation. We propose\na new strategy to speed up the DW motion in a uniaxial magnetic nanowire by\nusing an optimal space-dependent field pulse synchronized with the DW\npropagation. Depending on the damping parameter, the DW velocity can be\nincreased by about two orders of magnitude compared the standard case of a\nstatic uniform field. Moreover, under the optimal field pulse, the change in\ntotal magnetic energy in the nanowire is proportional to the DW velocity,\nimplying that rapid energy release is essential for fast DW propagation."
    },
    {
        "anchor": "Non-Ising domain walls in c-phase ferroelectric lead titanate thin films: Ferroelectrics are technologically important, with wide application in\nmicromechanical systems, nonlinear optics, and information storage. Recent\ndiscoveries of exotic polarisation textures in these materials, which can\nstrongly influence their properties, have brought to the forefront questions\nabout the nature of their domain walls -- long believed to be primarily Ising,\nwith locally null polarisation. Here, combining three complementary techniques\n-- second harmonic generation microscopy, piezoresponse force microscopy, and\ntransmission electron microscopy - to cover all the relevant lengthscales, we\nreveal the N\\'eel character (non-Ising polarisation oriented perpendicular to\nthe wall) of 180{\\deg} domain walls in c-phase tetragonal ferroelectric lead\ntitanate epitaxial thin films, for both artificial and intrinsic domains at\nroom temperature. Furthermore, we show that variations in the domain density --\ndetected both optically and via local piezoresponse, then quantified by radial\nautocorrelation analysis -- can give us insight into the underlying defect\npotential present in these materials.",
        "positive": "High-pressure effects on the optical-absorption edge of CdIn2S4,\n  MgIn2S4, and MnIn2S4 thiospinels: The effect of pressure on the optical-absorption edge of CdIn2S4, MgIn2S4,\nand MnIn2S4 thiospinels at room temperature is investigated up to 20 GPa. The\npressure dependence of their band-gaps has been analyzed using the Urbach rule.\nWe have found that, within the pressure-range of stability of the low-pressure\nspinel phase, the band-gap of CdIn2S4 and MgIn2S4 exhibits a linear blue-shift\nwith pressure, whereas the band-gap of MnIn2S4 exhibits a pronounced non-linear\nshift. In addition, an abrupt decrease of the band-gap energies occurs in the\nthree compounds at pressures of 10 GPa, 8.5 GPa, and 7.2 GPa, respectively.\nBeyond these pressures, the optical-absorption edge red-shifts upon compression\nfor the three studied thiospinels. All these results are discussed in terms of\nthe electronic structure of each compound and their reported structural\nchanges."
    },
    {
        "anchor": "Phase-field-crystal model for fcc ordering: We develop and analyze a two-mode phase-field-crystal model to describe fcc\nordering. The model is formulated by coupling two different sets of crystal\ndensity waves corresponding to <111> and <200> reciprocal lattice vectors,\nwhich are chosen to form triads so as to produce a simple free- energy\nlandscape with coexistence of crystal and liquid phases. The feasibility of the\napproach is demonstrated with numerical examples of polycrystalline and (111)\ntwin growth. We use a two-mode amplitude expansion to characterize analytically\nthe free-energy landscape of the model, identifying parameter ranges where fcc\nis stable or metastable with respect to bcc. In addition, we derive analytical\nexpressions for the elastic constants for both fcc and bcc. Those expressions\nshow that a non-vanishing amplitude of [200] density waves is essential to\nobtain mechanically stable fcc crystals with a non-vanishing tetragonal shear\nmodulus (C11 - C12)/2. We determine the model parameters for specific materials\nby fitting the peak liquid structure factor properties and solid density wave\namplitudes following the approach developed for bcc [K.-A. Wu and A. Karma,\nPhys. Rev. B 76, 184107 (2007)]. This procedure yields reasonable predictions\nof elastic constants for both bcc Fe and fcc Ni using input parameters from\nmolecular dynamics simulations. The application of the model to two-dimensional\nsquare lattices is also briefly examined.",
        "positive": "Testing several recent van der Waals density functionals for layered\n  structures: Six recently developed exchanged functionals for pairing with different two\nversions of van der Waals density functionals (vdW-DF) are tested for weakly\nbonded solids. The test, using 26 layered weakly bonded compounds, benchmarks\nthe lattice constants against experimental data and the interlayer binding\nenergies against reference data from the random-phase approximation (RPA). The\ninvestigated functionals tend to give interlayer binding energies higher than\nthe RPA benchmark, and the overall performance for lattice constants is good.\nThe exchange functionals optB86b and cx13 paired with the original vdW-DF and\nthe B86R functional paired with vdW-DF2 are found to give particularly good\nresults for equilibrium geometries."
    },
    {
        "anchor": "Finite element modeling of extraordinary optoconductance in GaAs-In\n  metal-semiconductor hybrid structures: We present a detailed discussion of extraordinary optoconductance (EOC).\nExperimental data was acquired via macroscopic metal-semiconductor hybrid\nstructures composed of GaAs and In and subjected to illumination from an Ar ion\nlaser. A drift diffusion model using the finite element method (FEM) provided a\nreasonable fit to the data. EOC is explored as a function of laser position,\nbias current, laser power density, and temperature. The positional dependence\nof the voltage is accounted for by the Dember effect, with the model\nincorporating the excess hole distribution based on the carrier mobility, and\nthus the mean free path. The bias current is found to produce a linear voltage\noffset and does not influence the EOC. A linear relationship is found between\nthe laser power density and the voltage in the bare and hybrid devices. This\ndependence is reproduced in the model by a generation rate parameter which is\nrelated to the power density. Incorporating the mobility and diffusion\ntemperature dependence, the model directly parallels the temperature dependence\nof the EOC without the use of fitting parameters.",
        "positive": "Effects of layer stacking and strain on electronic transport in 2D tin\n  monoxide: Tin monoxide is an interesting two-dimensional material because of the rare\noxide semiconductor with bipolar conductivity. However, the lower room\ntemperature mobility limits the applications of SnO in the future. Thus, we\nsystematically investigate the effects of the different layer structures and\nstrains on the electron-phonon coupling and phonon-limited mobility of SnO. The\nA2u phonon mode in the high frequency region is the main contributor coupling\nwith electron for the different layer structures. And the orbital hybridization\nof Sn atoms existing only in bilayer structure changes the conduction band edge\nand decreases the electron-phonon coupling conspicuously, thus the electronic\ntransport performance of bilayer is superior to others. In addition, the\ncompressive strain of -1.0% in monolayer structure makes CBM consist of two\nvalleys at Gamma point and along M-Gamma line, also leads to the intervalley\nelectronic scattering assisted by Eg-1 mode. However, the electron-phonon\ncoupling regional transferring from high frequency (A2u) to low frequency\n(Eg-1) results in the little significant change of mobility."
    },
    {
        "anchor": "Fermi sea term in the relativistic linear muffin-tin-orbital transport\n  theory for random alloys: We present a formulation of the so-called Fermi sea contribution to the\nconductivity tensor of spin-polarized random alloys within the fully\nrelativistic tight-binding linear muffin-tin-orbital (TB-LMTO) method and the\ncoherent potential approximation (CPA). We show that the configuration\naveraging of this contribution leads to the CPA-vertex corrections that are\nsolely due to the energy dependence of the average single-particle propagators.\nMoreover, we prove that this contribution is indispensable for the invariance\nof the anomalous Hall conductivities with respect to the particular LMTO\nrepresentation used in numerical implementation. Ab initio calculations for\ncubic ferromagnetic 3d transition metals (Fe, Co, Ni) and their random binary\nalloys (Ni-Fe, Fe-Si) indicate that the Fermi sea term is small against the\ndominating Fermi surface term. However, for more complicated structures and\nsystems, such as hexagonal cobalt and selected ordered and disordered Co-based\nHeusler alloys, the Fermi sea term plays a significant role in the quantitative\ntheory of the anomalous Hall effect.",
        "positive": "Oxidation of 2D electrenes: structural transition and the formation of\n  half-metallic channels protected by oxide layers: Based on first-principles calculations we performed a systematic study of the\nenergetic stability, structural characterization, and electronic properties of\nthe fully oxidized $A_{2}B$, electrenes, with the following combinations, (i)\n$A$=Ca, Sr, and Ba for $B$=N; (ii) $A$=Sr and Ba for $B$=P; and Y$_{2}$C, and\nBa$_{2}$As. We have considered one side oxidation of single layer electrenes\n$(O/A_{2}B)$, and two side oxidation of bilayer electrenes\n$(O/(A_{2}B)_{2}/O)$. We show that the hexagonal lattice of the pristine host\nis no longer the ground state structure in the oxidized systems. Our total\nenergy results reveal an exothermic structural transition from hexagonal to\ntetragonal (h$\\rightarrow$t) geometry, resulting in layered tetragonal\nstructures [$(AOAB)^{t}$, and $(AO(AB)_{2}AO)^{t}$]. Phonon spectra\ncalculations and molecular dynamic simulations show that the $O/A_{2}B$, and\n$O/(A_{2}B)_{2}/O$ systems, with $A$=Ba, Ca, Sr, and $B$=N, become dynamically\nand structurally stable upon such a h$\\rightarrow$t transition. Further\nstructural characterizations were performed based on simulations of the near\nedge X-ray absorption spectroscopy at the nitrogen K-edge. Finally, the\nelectronic structure calculations and transport calculations reveal the\nformation of half-metallic bands spreading out through the $A$N layers, which\nare shielded by oxide $A$O sheets. These findings indicate that $(AOAB)^{t}$,\nand $(AO(AB)_{2}AO)^{t}$, (with $B$=N) are quite interesting platforms for\napplication in spintronics; since the half-metallic channels along the $A$N or\n$(A\\text{N})_2$ layers (core) are protected against the environment conditions\nby the oxidized $A\\text{O}$ sheets (cover shells)."
    },
    {
        "anchor": "Crystal and Electronic Structure of GaTa$_4$Se$_8$ From First-Principle\n  Calculations: GaTa$_4$Se$_8$ belongs to the lacunar spinel family. Its crystal structures\nis still a puzzle though there have been intensive studies on its novel\nproperties, such as the Mott insulator phase and superconductivity under\npressure. In this work, we investigate its phonon spectra through\nfirst-principle calculations and proposed it most probably has crystal\nstructure phase transition, which is consistent with several experimental\nobservations. For the prototype lacunar spinel with cubic symmetry of space\ngroup $F\\bar{4}3m$, its phonon spectra have three soft modes in the whole\nBrillouin zone, indicating the strong dynamical instability of such crystal\nstructure. In order to find the dynamically stable crystal structure, further\ncalculations indicate two new structures of GaTa$_4$Se$_8$, corresponding to\n$R3m$ and $P\\bar{4}2_{1}m$, verifying that at the ambient pressure, there does\nexist structure phase transition of GaTa$_4$Se$_8$ from $F\\bar{4}3m$ to other\nstructures when the temperature is lowered. We also performed electronic\nstructure calculation for $R3m$ and $P\\bar{4}2_{1}m$ structure, showing that\n$P\\bar{4}2_{1}m$ structure GaTa$_4$Se$_8$ is band insulator, and obtained Mott\ninsulator state for $R3m$ structure by DMFT calculation under single-band\nHubbard model picture when interaction parameter U is larger than 0.40 eV vs.\nband width of 0.25 eV. It is reasonable to assume that while lowering the\ntemperature, $F\\bar{4}3m$ structure GaTa$_4$Se$_8$ becomes $R3m$ structure\nGaTa$_4$Se$_8$ first, then $P\\bar{4}2_{1}m$ structure GaTa$_4$Se$_8$, because\nof the symmetry of $P\\bar{4}2_{1}m$ is lower than $R3m$ after Jahn-Teller\ndistortion. The structure transition may explain the magnetic susceptibility\nanomalous at low temperature.",
        "positive": "Atomic-scale visualization of multiferroicity in monolayer NiI$_2$: Progress in layered van der Waals materials has resulted in the discovery of\nferromagnetic and ferroelectric materials down to the monolayer limit.\nRecently, evidence of the first purely two-dimensional multiferroic material\nwas reported in monolayer NiI$_2$. However, probing multiferroicity with\nscattering-based and optical bulk techniques is challenging on 2D materials,\nand experiments on the atomic scale are needed to fully characterize the\nmultiferroic order at the monolayer limit. Here, we use scanning tunneling\nmicroscopy (STM) supported by theoretical calculations based on density\nfunctional theory (DFT) to probe and characterize the multiferroic order in\nmonolayer NiI$_2$. We demonstrate that the type-II multiferroic order displayed\nby NiI$_2$, arising from the combination of a magnetic spin spiral order and a\nstrong spin-orbit coupling, allows probing the multiferroic order in the STM\nexperiments. Moreover, we directly probe the magnetoelectric coupling of\nNiI$_2$ by external electric field manipulation of the multiferroic domains.\nOur findings establish a novel point of view to analyse magnetoelectric effects\nat the microscopic level, paving the way towards engineering new multiferroic\norders in van der Waals materials and their heterostructures."
    },
    {
        "anchor": "Effects of opposite atoms on electronic structure and optical absorption\n  of two-dimensional hexagonal boron nitride: We perform the first-principles many-body GW and Bethe-Salpeter equation\n(BSE) calculations on the two-dimensional hexagonal boron nitride (2D-hBN) to\nexplore the effects of opposite atoms on the electronic structure and linear\none-photon absorption (OPA). Five AA- and AB-stacked bilayer and eight\nAAB-stacked trilayer structures are considered. The AAB-stacked trilayer hBN\n(TL-BN) structures are constructed by mixing the AA- and AB-stacked bilayer hBN\n(BL-BN). We show that the GW approximation gives rise to different types (i.e.,\nindirect or direct) of fundamental band gaps from the independent particle\napproximation for all structures except those dominated by the B-B opposite.\nThe stacking modes dominated by the B-B opposite have a direct fundamental band\ngap in both approximations. The OPA spectra are calculated by solving the\nBethe-Salpeter equation combined with the GW quasi-particle correction. Strong\nabsorption peaks are found for most structures in the deep-ultraviolet region.\nThe binding energy and Davydov splitting of excitons of TL-BN strongly depend\non the opposite atoms and are related to the role of the stacking BL-BN\nsubstructure. Finally, taking the six-layer and below AB-stacked structures as\nexamples, we show that the B-B opposite unit is helpful in constructing the\nturbostratic-phase-like stacking structures with a direct fundamental band gap\nwhich are more suitable for optoelectronic applications.",
        "positive": "Cascades damage in \u03b1-iron with high damage energy: We present a numerical study of the cascades damage in {\\alpha}-iron for high\ncascade energy up to 250keV, corresponding to neutron energy above and beyond\n14.1MeV. We observe that Frenkel pairs production efficiency and perfect\ncrystal lattices damage efficiency have the close trend within the statistical\nuncertainty versus cascade energy, and the two kinds of curves first decrease\nwith power-law trend, and arrive at their minimum at threshold energy of\nsubcascades, then these curves begin to increase with cascade energy. The\nanalysis demonstrates that the tendency of these curves reflects degree of\nconcentration of defects and depends on the number of subcascades which keeps\nidentical with defects scattering and the energy of subcascades reflecting\ndefects concentration. The pair analysis technique may help us understand the\ntotal damage of perfect crystal lattices."
    },
    {
        "anchor": "Synthesis and characterization of boron nitride powders produced under\n  concentrated light: Synthesis and research of the properties of boron nitride powders and BN\npowders with additives produced under effect of concentrated light in a flow of\nnitrogen in a xenon high-flux optical furnace are presented. A scanning and\ntransmission electron microscopes demonstrated structures of new morphologies\nfor the powders, which were formed. XRD, Raman scattering and electron\ndiffraction study have confirmed a complicated structure and phase composition\nof the powders with a prevalence of the amorphous phases. It was demonstrated\nan effect of experimental conditions, surface modification and additives on\nphase composition, morphology and structure formation. The gaseous model based\non an evolution of the bubble has been confirmed new nanostructure formation.\nBurst of these bubbles may result in graphene-like structures formation.",
        "positive": "Point Defects and Grain Boundaries in Rotationally Commensurate MoS2 on\n  Epitaxial Graphene: With reduced degrees of freedom, structural defects are expected to play a\ngreater role in two-dimensional materials in comparison to their bulk\ncounterparts. In particular, mechanical strength, electronic properties, and\nchemical reactivity are strongly affected by crystal imperfections in the\natomically thin limit. Here, ultra-high vacuum (UHV) scanning tunneling\nmicroscopy (STM) and spectroscopy (STS) are employed to interrogate point and\nline defects in monolayer MoS2 grown on epitaxial graphene (EG) at the atomic\nscale. Five types of point defects are observed with the majority species\nshowing apparent structures that are consistent with vacancy and interstitial\nmodels. The total defect density is observed to be lower than MoS2 grown on\nother substrates, and is likely attributed to the van der Waals epitaxy of MoS2\non EG. Grain boundaries (GBs) with 30{\\deg} and 60{\\deg} tilt angles resulting\nfrom the rotational commensurability of MoS2 on EG are more easily resolved by\nSTM than atomic force microscopy at similar scales due to the enhanced contrast\nfrom their distinct electronic states. For example, band gap reduction to ~0.8\neV and ~0.5 eV is observed with STS for 30{\\deg} and 60{\\deg} GBs,\nrespectively. In addition, atomic resolution STM images of these GBs are found\nto agree well with proposed structure models. This work offers quantitative\ninsight into the structure and properties of common defects in MoS2, and\nsuggests pathways for tailoring the performance of MoS2/graphene\nheterostructures via defect engineering."
    },
    {
        "anchor": "Type-II Dirac line node in strained Na3N: Dirac line node (DLN) semimetals are a class of topological semimetals that\nfeature band-crossing lines in momentum space. We study the type-I and type-II\nclassification of DLN semimetals by developing a criterion that determines the\ntype using band velocities. Using first-principles calculations, we also\npredict that Na3N under an epitaxial tensile strain realizes a type-II DLN\nsemimetal with vanishing spin-orbit coupling (SOC), characterized by the Berry\nphase that is Z2-quantized in the presence of inversion and time-reversal\nsymmetries. The surface energy spectrum is calculated to demonstrate the\ntopological phase, and the type-II nature is demonstrated by calculating the\nband velocities. We also develop a tight-binding model and a low-energy\neffective Hamiltonian that describe the low-energy electronic structure of\nstrained Na3N. The occurrence of a DLN in Na3N under strain is captured in the\noptical conductivity, which we propose as a means to experimentally confirm the\ntype-II class of the DLN semimetal.",
        "positive": "Mapping the magnetic exchange interactions from first principles:\n  Anisotropy anomaly and application to Fe, Ni, and Co: Mapping the magnetic exchange interactions from model Hamiltonian to density\nfunctional theory is a crucial step in multi-scale modeling calculations.\nConsidering the usual magnetic force theorem but with arbitrary rotational\nangles of the spin moments, a spurious anisotropy in the standard mapping\nprocedure is shown to occur provided by bilinear-like contributions of high\norder spin interactions. The evaluation of this anisotropy gives a hint on the\nstrength of non-bilinear terms characterizing the system under investigation."
    },
    {
        "anchor": "Peculiar metastable structural state in carbon steel: The kinetics of phase transformations at cooling of carbon steel in\ndependence on the temperature of preliminary annealing T$_{an}$ is studied. It\nis shown that the cooling from T$_{an}$ > A$_3$ (i. e. above the temperature of\nferrite start) with the rate 90 - 100 K/s results in structural state which\nessentially dependent on T$_{an}$; at 750$^0$C < T$_{an}$ < 830$^0$C the\ntransformation is of perlite type whereas at T$_{an}$ > 830$^0$C the\nmartensitic structure arises. Our results evidence the formation of a special\nstructural state in a certain range of temperatures near and above the boundary\nof two phase region which is characterized by a substantially nanoscale\nheterogeneity in carbon distribution, lattice distortions, and magnetic\nshort-range order.",
        "positive": "AutoEIS: automated Bayesian model selection and analysis for\n  electrochemical impedance spectroscopy: Electrochemical Impedance Spectroscopy (EIS) is a powerful tool for\nelectrochemical analysis; however, its data can be challenging to interpret.\nHere, we introduce a new open-source tool named AutoEIS that assists EIS\nanalysis by automatically proposing statistically plausible equivalent circuit\nmodels (ECMs). AutoEIS does this without requiring an exhaustive mechanistic\nunderstanding of the electrochemical systems. We demonstrate the\ngeneralizability of AutoEIS by using it to analyze EIS datasets from three\ndistinct electrochemical systems, including thin-film oxygen evolution reaction\n(OER) electrocatalysis, corrosion of self-healing multi-principal components\nalloys, and a carbon dioxide reduction electrolyzer device. In each case,\nAutoEIS identified competitive or in some cases superior ECMs to those\nrecommended by experts and provided statistical indicators of the preferred\nsolution. The results demonstrated AutoEIS's capability to facilitate EIS\nanalysis without expert labels while diminishing user bias in a high-throughput\nmanner. AutoEIS provides a generalized automated approach to facilitate EIS\nanalysis spanning a broad suite of electrochemical applications with minimal\nprior knowledge of the system required. This tool holds great potential in\nimproving the efficiency, accuracy, and ease of EIS analysis and thus creates\nan avenue to the widespread use of EIS in accelerating the development of new\nelectrochemical materials and devices."
    },
    {
        "anchor": "Analytical method to determine flexoelectric coupling coefficient at\n  nanoscale: Flexoelectricity is defined as the coupling between strain gradient and\npolarization, which is expected to be remarkable at nanoscale. However,\nmeasuring the flexoelectricity at nanoscale is challenging. In the present\nwork, an analytical method for measuring the flexoelectric coupling coefficient\nbased on nanocompression technique is proposed. It is found that the\nflexoelectricity can induce stiffness softening of dielectric\nnano-cone-frustum. This phenomenon becomes more significant when the sample\nsize decreases or the half cone angle increases. This method avoids measuring\nthe electric polarization or current at nanoscale with dynamical loading, which\ncan be beneficial to the flexoelectric measurement at nanoscale and design of\nflexoelectric nanodevices.",
        "positive": "Hardness Descriptor Derived from Symbolic Regression: Hardness is a materials' property with implications in the different\nindustrial fields, including oil and gas, manufacturing, and others. However,\nthe relationship between this macroscale property and atomic (i.e., microscale)\nproperties is unknown and in the last decade several models have tried to give\nan answer. The understanding of such relationship is of fundamental importance\nfor discovery of harder materials with specific characteristics to be employed\nin different fields. In this work, we have found a physical descriptor for\nVickers hardness using a symbolic-regression artificial-intelligence approach\nbased on compressed sensing. The approach (SISSO - sure independence screening\nplus sparsifying operator) combines materials' features (properties), obtained\nfrom atomistic simulations, with experimental values of the target property\n(Vikers hardness) for 635 compounds to develop the descriptor. The experimental\nvalues of hardness for binary, ternary, and quaternary transition-metal\nborides, carbides, nitrides, carbonitrides, carboborides, and boronitrides were\nincluded in the dataset. The found descriptor is a non-linear function of the\nmicroscopic properties, with the most significant contribution being from a\ncombination of Voigt-averaged bulk modulus, Poisson's ratio, and Reuss-averaged\nshear modulus. Results of high-throughput screening of 635 candidate materials\nusing the found descriptor suggest the enhancement of material's hardness\nthrough mixing with harder yet metastable structures (e.g., metastable VN, TaN,\nReN$_2$, Cr$_3$N$_4$, and ZrB$_6$ all exhibit high hardness)."
    },
    {
        "anchor": "Spontaneous Magnetization and Electron Momentum Density in 3D Quantum\n  Dots: We discuss an exactly solvable model Hamiltonian for describing the\ninteracting electron gas in a quantum dot. Results for a spherical square well\nconfining potential are presented. The ground state is found to exhibit\nstriking oscillations in spin polarization with dot radius at a fixed electron\ndensity. These oscillations are shown to induce characteristic signatures in\nthe momentum density of the electron gas, providing a novel route for direct\nexperimental observation of the dot magnetization via spectroscopies sensitive\nto the electron momentum density.",
        "positive": "Making large overhangs in micrometer and nanometer-sized structures: We describe two general procedures for fabricating microstructures with large\noverhangs and high aspect-ratio support pillars. The first method uses a static\nangled dry etch on micro- or nano-pillars to create an initial overhang,\nfollowed by wet etching for further erosion. The second method uses a\ntime-dependent angled etch on a flat plane patterned with protective resin, to\nreduce the number of lithography steps needed to make these objects. The\ntime-dependent dry etch is again followed by a wet etch. For the second method\nwe derive a formula that provides the rate at which the attack angle must\nevolve, given a known etch rate within the target material, the depth of the\ndesired overhang (undercut), and the instantaneous attack angle."
    },
    {
        "anchor": "Sharp Raman Anomalies and Broken Adiabaticity at a Pressure Induced\n  Transition from Band to Topological Insulator in Sb2Se3: The nontrivial electronic topology of a topological insulator is thus far\nknown to display signatures in a robust metallic state at the surface. Here, we\nestablish vibrational anomalies in Raman spectra of the bulk that signify\nchanges in electronic topology: an E2 g phonon softens unusually and its\nlinewidth exhibits an asymmetric peak at the pressure induced electronic\ntopological transition (ETT) in Sb2Se3 crystal. Our first-principles\ncalculations confirm the electronic transition from band to topological\ninsulating state with reversal of parity of electronic bands passing through a\nmetallic state at the ETT, but do not capture the phonon anomalies which\ninvolve breakdown of adiabatic approximation due to strongly coupled dynamics\nof phonons and electrons. Treating this within a four-band model of topological\ninsulators, we elucidate how nonadiabatic renormalization of phonons\nconstitutes readily measurable bulk signatures of an ETT, which will facilitate\nefforts to develop topological insulators by modifying a band insulator.",
        "positive": "Singular response to a dopant of an evaporating crystal surface: Moving crystal surfaces can undergo step-bunching instabilities, when subject\nto an electric current. We show analytically that an infinitesimal quantity of\na dopant may invert the stability, whatever the sign of the current. Our study\nis relevant for experimental results [S. S. Kosolobov et al., JETP Lett. 81,\n117 (2005)] on an evaporating Si(111) surface, which show a singular response\nto Au doping, whose density distribution is related to inhomogeneous Si\ndiffusion."
    },
    {
        "anchor": "Off-centered Pb interstitials in PbTe: In this work, we calculate the defect properties of low-symmetry Pb\ninterstitials in PbTe using first-principles density-functional theory\ncalculations. We break the symmetry imposed on on-centered interstitial defects\nand show that the lowest ground state of Pb interstitial defects is\noff-centered along the [111] directions. Due to the four multi-stable\nstructures with low defect formation energies, the defect density of Pb\ninterstitials is expected to be ~5.6 times larger than previous predictions\nwhen PbTe is synthesized at 900 K. In contrast to the on-centered\nPbinterstitial, the off-centered Pb interstitials in PbTe can exhibit\nlong-range lattice relaxation toward [111] direction beyond distance of 1 nm,\nindicating the potential formation of weak local dipoles. This result provides\nan alternative explanation for the emphanitic anharmonicity of PbTe.",
        "positive": "Finite viscoelasticity of filled rubbers: experiments and numerical\n  simulation: Constitutive equations are derived for the viscoelastic behavior of\nparticle-reinforced rubbers at isothermal loading with finite strains. A filled\nrubber is thought of as a composite medium where inclusions with high and low\nconcentrations of junctions between chains are randomly distributed in a host\nmatrix. The inclusions with high concentration of junctions are associated with\nregions of suppressed mobility of chains that surround isolated clusters of\nfiller and its secondary network. The regions with low concentration of\njunctions arise during the mixing process due to the inhomogeneity in spatial\ndistribution of a cross-linker. The viscoelastic response of elastomers is\nascribed to the thermally activated processes of breakage and reformation of\nstrands in the domains with low concentration of junctions. Stress-strain\nrelations for particle-reinforced rubbers are developed by using the laws of\nthermodynamics. Adjustable parameters in the constitutive equations are found\nby fitting experimental data in tensile relaxation tests for several grades of\nunfilled and carbon black (CB) filled rubber. It is demonstrated that the\nrelaxation rate is noticeably affected by strains. Unlike glassy polymers,\nwhere the growth of longitudinal strain results in an increase in the rate of\nrelaxation, the growth of the elongation ratio for natural rubber (unfilled or\nCB reinforced) implies a decrease in the relaxation rate, which may be\nexplained by partial crystallization of chains in the regions with low\nconcentration of junctions."
    },
    {
        "anchor": "Phonon screening and dissociation of excitons at finite temperatures\n  from first principles: The properties of excitons, or correlated electron-hole pairs, are of\nparamount importance to optoelectronic applications of materials. A central\ncomponent of exciton physics is the electron-hole interaction, which is\ncommonly treated as screened solely by electrons within a material. However,\nnuclear motion can screen this Coulomb interaction as well, with several recent\nstudies developing model approaches for approximating the phonon screening to\nthe properties of excitons. While these model approaches tend to improve\nagreement with experiment for exciton properties, they rely on several\napproximations that restrict their applicability to a wide range of materials,\nand thus far they have neglected the effect of finite temperatures. Here, we\ndevelop a fully first-principles, parameter-free approach to compute the\ntemperature-dependent effects of phonon screening within the ab initio GW-Bethe\nSalpeter equation framework. We recover previously proposed models of phonon\nscreening as well-defined limits of our general framework, and discuss their\nvalidity by comparing them against our first-principles results. We develop an\nefficient computational workflow and apply it to a diverse set of\nsemiconductors, specifically AlN, CdS, GaN, MgO and SrTiO3. We demonstrate\nunder different physical scenarios how excitons may be screened by multiple\npolar optical or acoustic phonons, how their binding energies can exhibit\nstrong temperature dependence, and the ultrafast timescales on which they\ndissociate into free electron-hole pairs.",
        "positive": "Structure of MnO nanoparticles embedded into channel-type matrices: X-ray diffraction experiments were performed on MnO confined in mesoporous\nsilica SBA-15 and MCM-41 matrices with different channel diameters. The\nmeasured patterns were analyzed by profile analysis and compared to numerical\nsimulations of the diffraction from confined nanoparticles. From the lineshape\nand the specific shift of the diffraction reflections it was shown that the\nembedded objects form ribbon-like structures in the SBA-15 matrices with\nchannels diameters of 47-87 {\\AA}, and nanowire-like structures in the MCM-41\nmatrices with channels diameters of 24-35 {\\AA}. In the latter case the\nconfined nanoparticles appear to be narrower than the channel diameters. The\nphysical reasons for the two different shapes of the confined nanoparticles are\ndiscussed."
    },
    {
        "anchor": "Development of interatomic potential appropriate for simulation of\n  dislocation migration in fcc Fe: Molecular dynamics (MD) simulation of dislocation migration requires\nsemi-empirical potentials of the interatomic interaction. While there are many\nreliable semi-empirical potentials for the bcc Fe, the number of the available\npotentials for the fcc is very limited. In the present study we tested three\nEAM potentials for the fcc Fe (ABCH97 [Phil. Mag. A, 75, 713-732 (1997)], BCT13\n[MSMSE 21, 085004 (2013)] and ZFS18 [J. Comp. Chem. 39, 2420-2431 (2018)]) from\nliterature. It was found that the ABCH97 potential does not provide that the\nfcc phase is the most stable at any temperature. On the other hand, the fcc\nphase is always more stable than the bcc phase for the BCT13, ZFS18 potentials.\nThe hcp phase is the most stable phase for the BCT13 potential at any\ntemperature. In order to fix these problems we developed two new EAM potentials\n(MB1 and MB2). The fcc phase is still more stable than the bcc phase for the\nMB1 potential but the MB2 potential provides that the bcc phase is the most\nstable phase from the upper fcc-bcc transformation temperature, T_gamma-delta,\nto the melting temperature, Tm, and the fcc phase is the most stable phase\nbelow T_gamma-delta. This potential also leads to an excellent agreement with\nthe experimental data on the fcc elastic constants and reasonable stacking\nfault energy which makes it the best potential for the simulation of the\ndislocation migration in the fcc Fe among all semi-empirical potentials\nconsidered in the present study. The MD simulation demonstrated that only the\nZFS18, MB1 and MB2 potentials are actually suitable for the simulation of the\ndislocation migration in the fcc Fe. They lead to the same orders of magnitude\nfor the dislocation velocities and all of them show that the edge dislocation\nis faster than the screw dislocation. However, the actual values of the\ndislocation velocities do depend on the employed semi-empirical potential.",
        "positive": "Local moment formation and magnetic coupling of Mn guest atoms in\n  Bi$_2$Se$_3$: a low-temperature ferromagnetic resonance study: We compare the magnetic and electronic configuration of single Mn atoms in\nmolecular beam epitaxy (MBE) grown Bi$_2$Se$_3$ thin films, focusing on\nelectron paramagnetic (ferromagnetic) resonance (EPR and FMR, respectively) and\nsuperconducting quantum interference device (SQUID) techniques. X-ray\ndiffraction (XRD) and electron backscatter diffraction (EBSD) reveal the\nexpected increase of disorder with increasing concentration of magnetic guest\natoms, however, Kikuchi patterns show that disorder consists majorly of\nmum-scale 60deg twin domains in the hexagonal Bi$_2$Se$_3$ structure, which are\npromoted by the presence of single unclustered Mn impurities. Ferromagnetism\nbelow T$_C$ ~ (5.4 +/- 0.3) K can be well described by critical scaling laws\nM(T) ~ (1-T/T$_C$)$^\\beta$ with a critical exponent $\\beta$ = (0.34 +/- 0.2)),\nsuggesting 3D Heisenberg class magnetism instead of e.g. 2D-type coupling\nbetween Mn-spins in van der Waals gap sites. From EPR hyperfine structure data\nwe determine a Mn$^{2+}$ (d$^5$, S = 5/2) electronic configuration with a\ng-factor of 2.002 for -1/2 --> +1/2 transitions. In addition, from the strong\ndependence of the low temperature FMR fields and linewidth on the field\nstrength and orientation with respect to the Bi$_2$Se$_3$ (0001) plane, we\nderive magnetic anisotropy energies of up to K1 = -3720 erg/cm3 in MBE-grown\nMn-doped Bi$_2$Se$_3$, reflecting the first order magneto-crystalline\nanisotropy of an in-plane magnetic easy plane in a hexagonal (0001) crystal\nsymmetry. Across the ferromagnetic-paramagnetic transition the FMR intensity is\nsuppressed and resonance fields converge the paramagnetic limit of a Mn$^{2+}$\n(d$^5$, S = 5/2)."
    },
    {
        "anchor": "Structure and Thermodynamical Properties of Zirconium hydrides from\n  first-principle: Zirconium alloys are used as nuclear fuel cladding material due to their\nmechanical and corrosion resistant properties together with their favorable\ncross-section for neutron scattering. At running conditions, however, there\nwill be an increase of hydrogen in the vicinity of the cladding surface at the\nwater side of the fuel. The hydrogen will diffuse into the cladding material\nand at certain conditions, such as lower temperatures and external load,\nhydrides will precipitate out in the material and cause well known\nembrittlement, blistering and other unwanted effects. Using phase-field methods\nit is now possible to model precipitation build-up in metals, for example as a\nfunction of hydrogen concentration, temperature and external load, but the\ntechnique relies on input of parameters, such as the formation energy of the\nhydrides and matrix. To that end, we have computed, using the density\nfunctional theory (DFT) code GPAW, the latent heat of fusion as well as solved\nthe crystal structure for three zirconium hydride polymorphs: \\delta-ZrH1.6,\n\\gamma-ZrH, and \\epsilon-ZrH2.",
        "positive": "Effect of randomly occurring Stone-Wales defects on mechanical\n  properties of carbon nanotubes using atomistic simulation: While CNTs are found to have ultra high stiffness and strength, an enormous\nscatter is also observed in available laboratory results. This paper studies\nthe effects of randomly distributed Stone Wales (SW or 5 7 7 5) defects on the\nmechanical properties of single walled nanotubes (SWNTs) using the technique of\natomistic simulation (AS). A Matern hard core random field applied on a finite\ncylindrical surface is used to describe the spatial distribution of the Stone\nWales defects. We simulate a set of displacement controlled tensile loading up\nto fracture of SWNTs with (6,6) armchair and (10, 0) zigzag configurations and\naspect ratio around 6. A modified Morse potential is adopted to model the\ninteratomic forces. We found that fracture invariably initiates from a defect\nif one is present; for a defect-free tube the crack initiates at quite random\nlocations. The force-displacement curve typically behaves almost linearly up to\nabout half way, although there is no obvious yield point. Three mechanical\nproperties - stiffness, ultimate strength and ultimate strain - are calculated\nfrom the simulated force and displacement time histories. The randomness in\nmechanical behavior resulting only from initial velocity distribution was found\nto be insignificant at room temperature. The mean values of stiffness, ultimate\nstrength and ultimate strain of the tube decrease as the average number of\ndefects increases although the coefficients of variation do not show such\nmonotonic trend. The introduction of an additional defect has the most\npronounced effect on the randomness in mechanical properties when the tube is\noriginally defect free. We also found that, for a given mean number of defects\nin the tube, the zigzag configuration has less strength and less ultimate\nstrain on the average, but more uncertainty in its stiffness and ultimate\nstrain, compared with the armchair tube."
    },
    {
        "anchor": "Nucleation Pathways in Barium Silicate Glasses: Nucleation is generally viewed as a structural fluctuation that passes a\ncritical size to eventually become a stable emerging new phase. However, this\nconcept leaves out many details, such as changes in cluster composition and\ncompeting pathways to the new phase. In this work, both experimental and\ncomputer modeling studies are used to understand the cluster composition and\npathways. Monte Carlo and molecular dynamics approaches are used to analyze the\nthermodynamic and kinetic contributions to the nucleation landscape in barium\nsilicate glasses. Experimental techniques examine the resulting polycrystals\nthat form. Both the modeling and experimental data indicate that a silica rich\ncore plays a dominant role in the nucleation process.",
        "positive": "Accurate analysis for harmonic Hall voltage measurement for spin-orbit\n  torques: An accurate method is developed to extract the spin-orbit effective fields\nthrough analysis of the results of harmonic Hall voltage measurements by\nderiving detailed analytical equations, in which both the z-component of the\napplied magnetic field and the second-order perpendicular magnetic anisotropy\nare taken into account. The method is tested by analyzing the results of a\nmacrospin simulation. The spin-orbit effective fields extracted from the\nanalysis are found to be in excellent agreement with the input spin-orbit\neffective fields used for the macrospin simulation over the entire range of the\npolar magnetization angle and a wide range (0-2) of the ratio of the planar to\nthe anomalous Hall voltage considered in this study. The accuracy of the\nproposed method is demonstrated more clearly via a systematic study involving a\ncomparison of its results with those of the conventional analytical method."
    },
    {
        "anchor": "Preparation of silver nanopatterns on DNA templates: Patterns of silver metal were prepared on DNA networks by a template-directed\nselective deposition and subsequent metallization process. Scanning force\nmicroscopic observations and XPS investigations demonstrated that uniform\nnetworks of nanosized silver metal clusters formed after incubation of DNA LB\nfilms with silver ions and subsequent chemical reduction of silver ions/DNA\nfilms samples. The results showed that this template-directed metallization on\nDNA LB films provided a simple and effective method for the construction of\nfunctional nanocomposite films.",
        "positive": "Toward an accurate equation of state and B1-B2 phase boundary for\n  magnesium oxide to TPa pressures and eV temperatures: By applying auxiliary-field quantum Monte Carlo, we calculate the equation of\nstate (EOS) and B1-B2 phase transition of magnesium oxide (MgO) up to 1 TPa.\nThe results agree with available experimental data at low pressures and are\nused to benchmark the performance of various exchange-correlation functionals\nin density functional theory calculations. We determine PBEsol is an optimal\nchoice for the exchange-correlation functional and perform extensive phonon and\nquantum molecular-dynamics calculations to obtain the thermal EOS. Our results\nprovide a preliminary reference for the EOS and B1-B2 phase boundary of MgO\nfrom zero up to 10,500 K."
    },
    {
        "anchor": "Effect of annealing on the magnetic, magnetocaloric and\n  magnetoresistance properties of Ni-Co-Mn-Sb melt spun ribbons: The structural, magnetic, magnetocaloric and magnetotransport properties of\nNi46Co4Mn38Sb12 melt spun ribbons have been systematically investigated. The\npartially ordered B2 phase of the as-spun ribbon transforms to fully ordered\nL21 phase upon annealing, which signifies a considerable change of the atomic\nordering in the system. The presence of atomic disorder in the as-spun ribbon\ngives rise to a higher martensitic transition temperature and a lower\nmagnetization as compared to the bulk sample. However, annealing the ribbons\nhelps in regaining the bulk properties to a large extent. Significant changes\nin magnetocaloric effect, exchange bias and magnetoresistance have been\nobserved between the as-spun and the annealed ribbons, indicating the role of\natomic ordering on the functional as well as fundamental properties in the\nHeusler system. Importantly, the study shows that one can reduce the hysteresis\nloss by preparing melt spun alloys and subjecting them to appropriate annealing\nconditions, which enable them to become practical magnetic refrigerants.",
        "positive": "Temperature evolution of infrared- and Raman-active phonons in graphite: We perform a comparative experimental and theoretical study of the\ntemperature dependence up to 700 K of the frequency and linewidths of the\ngraphite E1u and E2g optical phonons (~1590 and 1580 cm-1) by infra-red (IR)\nand Raman spectroscopy. Despite their similar character, the temperature\ndependence of the two modes is quite different, being, e.g., the frequency\nshift of the IR-active E1u mode is almost twice as big as that of the Raman\nactive E2g mode. Ab initio calculations of the anharmonic properties are in\nremarkable agreement with measurements and explain the observed behavior."
    },
    {
        "anchor": "Probing Lithium Ion Transport at Individual Interfaces: Ion transport across solid solid interfaces is often slower than through the\nbulk of a material, impeding the charge and discharge rate of batteries.\nDesigning highly conductive interfaces is challenging due to the need to probe\nion conduction at individual interfaces and correlate it with the local\nstructure. In this study, we address this challenge by enabling the\nsimultaneous measurements of local Li-dominated optical phonons and ion\ndistributions, using high-energy and high-spatial-resolution spectroscopy in a\nscanning transmission electron microscope (STEM). Further, this method allows\nfor a direct correlation of ion conduction with interfacial structures\nidentified by STEM imaging. By examining diverse individual interfaces of\nLiCoO2, we reveal the sensitivity of ion conduction to interface atomic-scale\nstructure and chemistry. Our method enables correlative analysis of ion\ntransport behavior, and atomic and band structures, and can serve as a robust\nexperimental approach for identifying interface structures that offer high\nconductivity and cyclability for batteries.",
        "positive": "Potential barrier heights at metal on oxygen-terminated diamond\n  interfaces: Electrical properties of metal-semiconductor (M/SC) and metal/oxide/SC\nstructures built with Zr or ZrO\\_2 deposited on oxygen-terminated surfaces of\n(001)-oriented diamond films, comprising a stack of lightly p-doped diamond on\na heavily doped layer itself homoepitaxially grown on a Ib substrate, are\ninvestigated experimentally and compared to different models. In Schottky\nbarrier diodes, the interfacial oxide layer evidenced by high resolution\ntransmission electron microscopy and electron energy losses spectroscopy before\nand after annealing, and barrier height inhomogeneities accounts for the\nmeasured electrical characteristics until flat bands are reached, in accordance\nwith a model which generalizes that of R.T. Tung [Phys. Rev. B 45, 13509\n(1992)] and permits to extract physically meaningful parameters of the three\nkinds of interface: (a) unannealed ones; (b) annealed at 350{\\textdegree}C; (c)\nannealed at 450{\\textdegree}C, with characteristic barrier heights of 2.2-2.5 V\nin case (a) while as low as 0.96 V in case (c). Possible models of potential\nbarriers for several metals deposited on well defined oxygen-terminated diamond\nsurfaces are discussed and compared to experimental data. It is concluded that\ninterface dipoles of several kinds present at these compound interfaces and\ntheir chemical evolution due to annealing are the suitable ingredients able to\naccount for the Mott-Schottky behavior when the effect of the metal work\nfunction is ignored, and to justify the reverted slope observed regarding metal\nwork function, in contrast to the trend always reported for all other\nmetal-semiconductor interfaces."
    },
    {
        "anchor": "Combinatorial sputter deposition of CrMnFeCoNi high entropy alloy thin\n  films on agitated particles: A method for combinatorial sputter deposition of thin films on microparticles\nis presented. The method is developed for a laboratory-scale magnetron sputter\nsystem and uses a piezoelectric actuator to agitate the microparticles through\noscillation. Custom-made components enable to agitate up to nine separate\nbatches of particles simultaneously. Due to the agitation, the whole surface of\nthe particles can be exposed to the sputter flux and thus can be completely\ncovered with a thin film. By sputtering a CrMnFeCoNi high entropy alloy target,\nseparate batches of polystyrene microspheres (500 um monodisperse diameter), Fe\nalloy particles (300 um mean size) and NaCl salt particles (350 um mean size)\nwere simultaneously coated with a homogeneous thin film. In contrast, a\nCrMnFeCoNi thin film that was deposited on agglomerating Al particles (5 um\nmean size) only partially covers the surface of the particles. By co-sputtering\na CrMn, an FeCo and a Ni target, nine separate batches of Al particles (25 um\nmean size) were coated with a CrMnFeCoNi thin film with a composition gradient.\nThese depositions demonstrate the ability to coat different types of particles\nwith uniform films (from elemental to multinary compositions) and to deposit\nfilms with composition gradients on uniform particles.",
        "positive": "Creation of crystal structure reproducing X-ray diffraction pattern\n  without using database: When a sample's X-ray diffraction pattern (XRD) is measured, the\ncorresponding crystal structure is usually determined by searching for similar\nXRD patterns in the database. However, if a similar XRD pattern is not found,\nit is tremendously laborious to identify the crystal structure even for\nexperts. This case commonly happens when researchers develop novel and complex\nmaterials. In this study, we propose a crystal structure creation scheme that\nreproduces a given XRD pattern. We employed a combinatorial inverse design\nmethod using an evolutionary algorithm and crystal morphing (Evolv&Morph)\nsupported by Bayesian optimization, which maximizes the similarity of the XRD\npatterns between target one and those of the created crystal structures. For\nsixteen different crystal structure systems with twelve simulated and four\npowder target XRD patterns, Evolv&Morph successfully created crystal structures\nwith the same XRD pattern as the target (cosine similarity > 99% for the\nsimulated ones and > 96% the experimentally-measured ones). Furthermore, the\npresent method has merits in that it is an automated crystal structure creation\nscheme, not dependent on a database. We believe that Evolv&Morph can be applied\nnot only to determine crystal structures but also to design materials for\nspecific properties."
    },
    {
        "anchor": "An operational window for radiation-resistant materials based on\n  sequentially healing grain interiors and boundaries: Design of nuclear materials with high radiation-tolerance has great\nsignificance1, especially for the next generation of nuclear energy systems2,3.\nResponse of nano- and poly-crystals to irradiation depends on the radiation\ntemperature, dose-rate and grain size4-13. However the dependencies had been\nstudied and interpreted individually, and thus severely lacking is the ability\nto predict radiation performance of materials in extreme environments. Here we\npropose an operational window for radiation-resistant materials, which is based\non a perspective of interactions among irradiation-induced interstitials,\nvacancies, and grain boundaries. Using atomic simulations, we find that healing\ngrain boundaries needs much longer time than healing grain interiors. Not been\nnoticed before, this finding suggests priority should be thereafter given to\nrecovery of the grain boundary itself. This large disparity in healing time is\nreflected in the spectra of defects-recombination energy barriers by the\npresence of one high-barrier peak in addition to the peak of low barriers. The\ninsight gained from the study instigates new avenues for examining the role of\ngrain boundaries in healing the material. In particular, we sketch out the\nradiation-endurance window in the parameter space of temperature, dose-rate and\ngrain size. The window helps evaluate material performance and develop\nresistant materials against radiation damage.",
        "positive": "Evolution of the magnetic and structural properties of\n  Fe$_{1-x}$Co$_x$V$_2$O$_4$: The magnetic and structural properties of single crystal\nFe$_{1-x}$Co$_x$V$_2$O$_{4}$ samples have been investigated by performing\nspecific heat, susceptibility, neutron diffraction, and X-ray diffraction\nmeasurements. As the orbital-active Fe$^{2+}$ ions with larger ionic size are\ngradually substituted by the orbital-inactive Co$^{2+}$ ions with smaller ionic\nsize, the system approaches the itinerant electron limit with decreasing V-V\ndistance. Then, various factors such as the Jahn-Teller distortion and the\nspin-orbital coupling of the Fe$^{2+}$ ions on the A sites and the orbital\nordering and electronic itinerancy of the V$^{3+}$ ions on the B sites compete\nwith each other to produce a complex magnetic and structural phase diagram.\nThis phase diagram is compared to those of Fe$_{1-x}$Mn$_x$V$_2$O$_{4}$ and\nMn$_{1-x}$Co$_x$V$_2$O$_{4}$ to emphasize several distinct features."
    },
    {
        "anchor": "Realization of multifunctional shape-memory ferromagnets in all-d-metal\n  Heusler phases: Heusler ferromagnetic shape-memory alloys (FSMAs) normally consist of\ntransition-group d-metals and main-group p-elements. Here, we report the\nrealization of FSMAs in Heusler phases that completely consist of d metals. By\nintroducing the d-metal Ti into NiMn alloys, cubic B2-type Heusler phase is\nobtained and the martensitic transformation temperature is decreased\nefficiently. Strong ferromagnetism is established by further doping Co atoms\ninto the B2-type antiferromagnetic Ni-Mn-Ti austenite. Based on the\nmagnetic-field-induced martensitic transformations, collective multifunctional\nproperties are observed in Ni(Co)-Mn-Ti alloys. The d metals not only\nfacilitate the formation of B2-type Heusler phases, but also establish strong\nferromagnetic coupling and offer the possibility to tune the martensitic\ntransformation.",
        "positive": "Enhanced thermal stability of dielectric and energy storage properties\n  in 0.4BCZT-0.6BTSn lead-free ceramics elaborated by sol-gel method: Polycrystalline lead-free Ba$_{0.85}$Ca$_{0.15}$Zr$_{0.10}$Ti$_{0.90}$O$_3$\n(BCZT), BaTi$_{0.89}$Sn$_{0.11}$O$_3$ (BTSn) and\n0.4Ba$_{0.85}$Ca$_{0.15}$Zr$_{0.10}$Ti$_{0.90}$O$_3$-0.6BaTi$_{0.89}$Sn$_{0.11}$O$_3$\n(0.4BCZT-0.6BTSn) ferroelectric ceramics were prepared via sol gel process and\ntheir structural, dielectric and energy storage properties were studied. Pure\nperovskite structure was confirmed by X ray diffraction analysis. The evolution\nof energy storage performances with temperature was studied. A Significant\nrecoverable energy storage density of 137.86 mJ/cm$^3$ and high energy-storage\nefficiency of 86.19% under a moderate electric field of 30 kV/cm were achieved\nin the composite 0.4BCZT 0.6BTSn ceramic at 353 $^\\circ$K. Moreover, excellent\ntemperature stability (70-130 $^\\circ$C) of the energy storage efficiency (less\nthan 3%) was achieved."
    },
    {
        "anchor": "Silicene nanoribbons on an insulating thin film: Silicene, a new two-dimensional (2D) material has attracted intense research\nbecause of the ubiquitous use of silicon in modern technology. However,\nproducing free-standing silicene has proved to be a huge challenge. Until now,\nsilicene could be synthesized only on metal surfaces where it naturally forms\nstrong interactions with the metal substrate that modify its electronic\nproperties. Here, we report the first experimental evidence of silicene sheet\non an insulating NaCl thin film. This work represents a major breakthrough; for\nthe study of the intrinsic properties of silicene, and by extension to other 2D\nmaterials that have so far only been grown on metal surfaces.",
        "positive": "High-Tc Superconductors - based Nanocomposites with Improved Intergrain\n  Coupling and Enhanced Bulk Pinning: Heterogeneous sonochemical synthesis was used to modify superconducting\nproperties of granular YBa2Ca3CuO7-y and Bi2Sr2CaCu2O8+x. Sonication of\nliquid-powder alkane slurries produces material with enhanced intergrain\ncoupling and improved current-carrying capabilities. Co-sonication with metals\nand organometallics results in highly compact nanocomposites with increased\nmagnetic irreversibility. Ultrasonic irradiation of YBa2Ca3CuO7-y carried under\npartial oxygen atmosphere produces similar morphological effects and increases\nsuperconducting transition temperature due to effective surface saturation with\noxygen. Detailed chemical and physical characterization of sonochemically\nprepared high-Tc nanocomposites is presented."
    },
    {
        "anchor": "Large magnetoresistance in LaBi: origin of field-induced resistivity\n  upturn and plateau in compensated semimetals: The discovery of non-magnetic extreme magnetoresistance (XMR) materials has\ninduced great interests because the XMR phenomenon challenges our understanding\nof how a magnetic field can alter electron transport in semimetals. Among XMR\nmaterials, the LaSb shows XMR and field-induced exotic behaviors but it seems\nto lack the essentials for these properties. Here, we study the\nmagnetotransport properties and electronic structure of LaBi, isostructural to\nLaSb. LaBi exhibits large MR as in LaSb, which can be ascribed to the nearly\ncompensated electron and hole with rather high mobilities. More importantly,\nour analysis suggests that the XMR as well as field-induced resistivity upturn\nand plateau observed in LaSb and LaBi can be well explained by the two-band\nmodel with the compensation situation. We present the critical conditions\nleading to these field-induced properties. It will contribute to understanding\nthe XMR phenomenon and explore novel XMR materials.",
        "positive": "Uniform diamond coatings on WC-Co hard alloy cutting inserts deposited\n  by a microwave plasma CVD: Polycrystalline diamond coatings have been grown on cemented carbide\nsubstrates with different aspect ratios by a microwave plasma CVD in\nmethane-hydrogen gas mixtures. To protect the edges of the substrates from\nnon-uniform heating due to the plasma edge effect, a special plateholder with\npockets for group growth has been used. The difference in heights of the\nsubstrates and plateholder, and its influence on the diamond film mean grain\nsize, growth rate, phase composition and stress was investigated. The substrate\ntemperature range, within which uniform diamond films are produced with good\nadhesion, is determined. The diamond-coated cutting inserts produced at\noptimized process exhibited a reduction of cutting force and wear resistance by\na factor of two, and cutting efficiency increase by 4.3 times upon turning A390\nAl-Si alloy as compared to performance of uncoated tools."
    },
    {
        "anchor": "Generic failure mechanisms in adhesive bonds: The failure of adhesive bondlines has been studied at the microscopic level\nvia tensile tests. Stable crack propagation could be generated by means of\nsamples with improved geometry, which made in-situ observations possible. The\ninteraction of cracks with adhesive bondlines under various angles to the crack\npropagation was the focus of this study as well as the respective loading\nsituations for the adhesives UF, PUR, and PVAc, which have distinctly different\nmechanical behaviors. It is shown how adhesive properties influence the\noccurrence of certain failure mechanisms and determine their appearance and\norder of magnitude. With the observed failure mechanisms, it becomes possible\nto predict the propagation path of a crack through the specimen.",
        "positive": "Enhanced photovoltaic effect in graphene-silicon Schottky junction under\n  mechanical manipulation: Graphene-silicon Schottky junction (GSJ) which has the potential for\nlarge-scale manufacturing and integration can bring new opportunities to\nSchottky solar cells for photovoltaic (PV) power conversion. However, the\nessential power conversion limitation for these devices lies in the small\nopen-circuit voltage ($V_{oc}$), which depends on the Schottky barrier height\n(SBH). In this study, we introduce an electromechanical method based on the\nflexoelectric effect to enhance the PV efficiency in GSJ. By atomic force\nmicroscope (AFM) tip-based indentation and in situ current measurement, the\ncurrent-voltage (I-V) responses under flexoelectric strain gradient are\nobtained. The $V_{oc}$ is observed to increase for up to 20$\\%$, leading to an\nevident improvement of the power conversion efficiency. Our studies suggest\nthat strain gradient may offer unprecedented opportunities for the development\nof GSJ based flexo-photovoltaic applications."
    },
    {
        "anchor": "Antiferromagnetic multi-level memristor using linear magnetoelectricity: The explosive growth of artificial intelligence and data-intensive computing\nhas brought crucial challenge to modern information science and technology,\ni.e. conceptually new devices with superior properties are urgently desired.\nMemristor is recognized as a very promising circuit element to tackle the\nbarriers, because of its fascinating advantages in imitating neural network of\nhuman brain, and thus realizing in-memory computing. However, there exist two\ncore and fundamental issues: energy efficiency and accuracy, owing to the\nelectric current operation of traditional memristors. In the present work, we\ndemonstrate a new type of memristor, i.e. charge q and magnetic flux {\\phi}\nspace memristor, enabled by linear magnetoelectricity of Co4Nb2O9. The memory\nstates show distinctly linear magnetoelectric coefficients with a large ratio\nof about 10, ensuing exceptional accuracy of related devices. The present\nq-{\\phi} type memristor can be manipulated by magnetic and electric fields\nwithout involving electric current, paving the way to develop\nultralow-energy-consuming devices. In the meanwhile, it is worth to mention\nthat Co4Nb2O9 hosts an intrinsic compensated antiferromagnetic structure, which\nsuggests interesting possibility of further integrating the unique merits of\nantiferromagnetic spintronics such as ultrahigh density and ultrafast\nswitching. Linear magnetoelectricity is proposed to essential to the q-{\\phi}\ntype memristor, which would be accessible in a broad class of multiferroics and\nother magnetoelectric materials such as topological insulators. Our findings\ncould therefore advance memristors towards new levels of functionality.",
        "positive": "The Growth of New Extended Carbon Nanophases from Ferrocene Inside\n  Single-Walled Carbon Nanotubes: The Raman response of new structures grown after filling SWCNTs with\nferrocene and transformation at moderate high temperatures is demonstrated to\nbe very strong, even stronger than the response from the tubes. Transmission\nelectron microscopy demonstrates that the new objects are flat and exhibit a\nstructure similar to short fragments of nanoribbons. The growth process is\ncontrolled by two different activation energies for low and high transformation\ntemperatures, respectively. Immediately after filling Raman pattern from a\nprecursor molecule are detected. Two different types of nanoribbons were\nidentified by selecting special laser energies for the Raman excitation. These\nribbons have the signature of quaterrylene and terrylene, respectively."
    },
    {
        "anchor": "Ultrafast Third-Order Nonlinear Optical Response of Charge Coupled Gold\n  Nanoparticle-Ge24Se76 Heterostructure: The donor-acceptor interaction of a charge-coupled heterostructure\nencompassing a metal and an amorphous semiconductor subjected to a laser field\nhas many potential applications in the realm of nonlinear optics. In this work,\nwe fabricate an electron donor gold nanoparticle (AuNP) and acceptor amorphous\nGe24Se76 heterostructure on a quartz substrate using a sequential thermal\nevaporation technique. In this charge-coupled heterostructure, we demonstrate\nthe ultrafast third-order nonlinear absorptive and refractive response and\ntheir sign reversal compared to pristine Ge24Se76. Enhanced optical\nnonlinearity in these heterostructures of varying plasmonic wavelengths is due\nto charge transfer, verified by the Raman spectroscopy. Further, the ultrafast\ntransient absorption measurements support the thesis of charge transfer in the\nAuNP/Ge24Se76 heterostructure. These findings open up exciting opportunities\nfor developing novel device technologies with far-reaching applications in\nnonlinear optics.",
        "positive": "Investigation of induced Pt magnetic polarization in Pt/Y3Fe5O12\n  bilayers: Using X-ray magnetic circular dichroism (XMCD) measurements, we explore the\npossible existence of induced magnetic moments in thin Pt films deposited onto\nthe ferrimagnetic insulator yttrium iron garnet (Y3Fe5O12). Such a magnetic\nproximity effect is well established for Pt/ferromagnetic metal\nheterostructures. Indeed, we observe a clear XMCD signal at the Pt L3 edge in\nPt/Fe bilayers, while no such signal can be discerned in XMCD traces of\nPt/Y3Fe5O12 bilayers. Integrating the XMCD signals allows to estimate an upper\nlimit for the induced Pt magnetic polarization in Pt/Y3Fe5O12 bilayers."
    },
    {
        "anchor": "Donor type semiconductor at low temperature as maser active medium: In some semiconductors donor impurity atoms can attract additional electrons,\nforming negative donor impurity ions. Thus we have 3 energy levels for\nelectrons: zero energy levels at the bottom of the conductivity band, negative\nenergy levels of the bounded electrons of the negative donor impurity ions, and\ndeeper negative energy levels of the outer electrons of the neutral donor\nimpurity atoms. So the donor impurity atoms could serve as active centres for a\nmaser. The maximum achievable relative population is 0.5. Typical wavelength of\nthe generated oscillation is 0.14 mm; three level scheme could be realized at\nrather low temperatures, considerably lower than 6 K.",
        "positive": "Coexistence of zero-, one- and two-dimensional degeneracy in tetragonal\n  SnO$_2$ phonons: Based on the dimension of degeneracy, topological electronic systems can\nroughly be divided into three parts: nodal point, line and surface materials\ncorresponding to zero-, one- and two-dimensional degeneracy, respectively. In\nparallel to electronic systems, the concept of topology was extended to\nphonons, promoting the birth of topological phonons. Till date, few nodal\npoint, line and surface phonons candidates have been predicted in solid-state\nmaterials. In this study, based on symmetry analysis and first-principles\ncalculation, for the first time, we prove that zero-, one- and two-dimensional\ndegeneracy co-exist in the phonon dispersion of one single realistic\nsolid-state material SnO$_2$ with \\textit{P}4$_2$/\\textit{mnm} structure. In\ncontrast to the previously reported electronic systems, the topological phonons\nobserved in SnO$_2$ are not restricted by the Pauli exclusion principle, and\nthey experience negligible spin-orbit coupling effect. Hence, SnO$_2$ with\nmultiple dimensions of degeneracy phonons is a good platform for studying the\nentanglement among nodal point, line and surface phonons. Moreover, obvious\nphonon surface states are visible, which is beneficial for experimental\ndetection."
    },
    {
        "anchor": "Atomic structure and electronic properties of nanotubes of layered\n  iron-based superconductors: The atomic models of nanotubes for layered FeSe, LiFeAs, SrFe2As2, and\nLnFeAsO - the parent phases of so-called 11, 111, 122, and 1111 groups of newly\ndiscovered family of iron-based high temperature superconductors are proposed.\nOn example of SrFe2As2 the electronic properties of predicted nanotubes are\nexamined and discussed in comparison with those for the corresponding single\nlayer and the crystal.",
        "positive": "Chemical reactivity and magnetism of graphene: The basic problem of weak interaction between odd electrons in graphene is\nconsidered within the framework of broken spin-symmetry approach. The latter\nexhibits the peculiarities of the odd electron behavior via both enhanced\nchemical reactivity and magnetism."
    },
    {
        "anchor": "Observation of plateau-like magnetoresistance in twisted\n  Fe3GeTe2/Fe3GeTe2 junction: Controlling the stacking of van der Waals (vdW) materials is found to produce\nexciting new findings, since hetero- or homo- structures have added the diverse\npossibility of assembly and manipulated functionalities. However, so far, the\nhomostructure with a twisted angle based on the magnetic vdW materials remains\nunexplored. Here, we achieved a twisted magnetic vdW Fe3GeTe2/Fe3GeTe2 junction\nwith broken crystalline symmetry. A clean and metallic vdW junction is\nevidenced by the temperature-dependent resistance and the linear I-V curve.\nUnlike the pristine FGT, a plateau-like magnetoresistance (PMR) is observed in\nthe magnetotransport of our homojunction due to the antiparallel magnetic\nconfigurations of the two FGT layers. The PMR ratio is found to be ~0.05% and\ngets monotonically enhanced as temperature decreases like a metallic giant\nmagnetoresistance (GMR). Such a tiny PMR ratio is at least three orders of\nmagnitude smaller than the tunneling magnetoresistance (TMR) ratio, justifying\nour clean metallic junction without a spacer. Our findings demonstrate the\nfeasibility of the controllable homostructure and shed light on future\nspintronics using magnetic vdW materials.",
        "positive": "Universal kinetics of the stochastic formation of polarization domain\n  structures in a uniaxial single-crystal ferroelectric: Initial conditions after quenching from a high-temperature paraelectric phase\nto a low-temperature ferroelectric phase have a substantial impact on the\ntemporal development and formation of stable polarization domain structures\nwhich eventually determine physical properties and the functionality of\nferroelectrics. Based on the recently advanced exactly solvable model of the\nstochastic domain structure kinetics in a uniaxial ferroelectric [Phys. Rev. B\n107, 144109 (2023)], we study the effect of the magnitude of the initial\ndisorder, its initial correlation length and polarization correlation function\non the system evolution. For different shapes of the initial correlation\nfunction, the time-dependent correlation length and the two-point polarization\ncorrelation coefficient are calculated analytically demonstrating universal\nfeatures and a good agreement with the available experimental data.\nParticularly, the magnitude of the charge density correlation function reveals\na strong reduction of the bound charges at the nominally charged domain walls\nwhich was recently observed experimentally in uniaxial ferroelectrics.\nConsequently, the integrodifferential equations of evolution for the\npolarization correlation function and the mean polarization are numerically\nsolved for different initial conditions. The temporal dependence of the\npolarization mean value and variance are evaluated demonstrating the\nbifurcation behavior depending on the applied electric field. The impact of the\ninitial state properties on the coercive field deciding between the single- and\nmulti-domain final states of the system is disclosed."
    },
    {
        "anchor": "Spin-dependent transport properties in GaMnAs-based spin hot-carrier\n  transistors: We have investigated the spin-dependent transport properties of GaMnAs-based\nthree-terminal semiconductor spin hot-carrier transistor (SSHCT) structures.\nThe emitter-base bias voltage VEB dependence of the collector current IC,\nemitter current IE, and base current IB shows that the current transfer ratio\nalpha (= IC / IE) and the current gain beta (= IC / IB) are 0.8-0.95 and 1-10,\nrespectively, which means that GaMnAs-based SSHCTs have current amplifiability.\nIn addition, we observed an oscillatory behavior of the tunneling\nmagnetoresistance (TMR) ratio with the increasing bias, which can be explained\nby the resonant tunneling effect in the GaMnAs quantum well.",
        "positive": "Defect model for the mixed mobile ion effect revisited: an importance of\n  deformation rates: The progress in understanding the behavior of glassy mixed ionic conductors\nwithin the concept of the defect model for the mixed mobile ion effect (V.\nBelostotsky, J. Non-Cryst. Solids 353 (2007) 1078) is reported. It is shown\nthat in a mixed ionic conductor (e.g., mixed alkali glass) containing two or\nmore types of dissimilar mobile ions of unequal size sufficient local strain\narising from the size mismatch of a mobile ion entering a foreign site can not\nbe, in principle, absorbed by the surrounding network-forming matrix without\nits damage. Primary site rearrangement occurs immediately, on the time scale\nclose to that of the ion migration process, through the formation of intrinsic\ndefects in the nearest glass network. Neither anelastic relaxation below glass\ntransition temperature, Tg, nor viscoelastic or viscous behavior at or above Tg\ncan be expected being observed in this case because the character of the stress\nrelaxation in a wide temperature range is dictated above all by the deformation\nrates employed locally to the adjacent network-forming matrix. Since the ion\nmigration occurs on the picosecond time scale, the primary rearrangement of the\nglass network adjacent to an ionic site occurs at rates orders of magnitude\nhigher than those of the critical minimum values, so the matrix demonstrates\nbrittle-elastic response to the arising strain even at temperatures well above\nTg, which explains, among other things, why mixed alkali effect is observable\nin glass melts."
    },
    {
        "anchor": "Ab initio quality study of the graphite-diamond phase coexistence: An interatomic potential for the diamond and graphite phases of carbon has\nbeen created using a neural-network (NN) representation of the ab initio\npotential energy surface. The NN potential combines the accuracy of a\nfirst-principle description of both phases with the efficiency of empirical\nforce fields and allows one to perform, for the first time, a molecular\ndynamics study, of ab initio quality, of the thermodynamics of graphite-diamond\ncoexistence. Good agreement between the experimental and calculated coexistence\ncurves is achieved if nuclear quantum effects are included in the simulation.",
        "positive": "Density functional theory study of Fe(II) adsorption and oxidation on\n  goethite surfaces: We study the interactions between Fe(II) aqua complexes and surfaces of\ngoethite (alpha-FeOOH) by means of density functional theory calculations\nincluding the so-called Hubbard U correction to the exchange-correlation\nfunctional. Using a thermodynamic approach, we find that (110) and (021)\nsurfaces in contact with aqueous solutions are almost equally stable, despite\nthe evident needlelike shape of goethite crystals indicating substantially\ndifferent reactivity of the two faces. We thus suggest that crystal anisotropy\nmay result from different growth rates due to virtually barrierless adsorption\nof hydrated ions on the (021) but not on the (110) surface. No clear evidence\nis found for spontaneous electron transfer from an adsorbed Fe(II) hex-aqua\ncomplex to a defect-free goethite substrate. Crystal defects are thus inferred\nto play an important role in assisting such electron transfer processes\nobserved in a recent experimental study. Finally, goethite surfaces are\nobserved to enhance the partial oxidation of adsorbed aqueous Fe(II) upon\nreaction with molecular oxygen. We propose that this catalytic oxidation effect\narises from donation of electronic charge from the bulk oxide to the oxidizing\nagent through shared hydroxyl ligands anchoring the Fe(II) complexes on the\nsurface."
    },
    {
        "anchor": "CO-induced lifting of Au (001) surface reconstruction: We report CO-induced lifting of the hexagonal surface reconstruction on Au\n(001). Using in-situ surface x-ray scattering, we determined a\npressure-temperature phase diagram for the reconstruction and measured the\ndynamical evolution of the surface structure in real time. Our observations\nprovide evidence that, under certain conditions, even macroscopic Au surfaces,\nmuch larger than catalytic Au nanoparticles [M. Haruta, Catal. Today 36, 153\n(1997)], can exhibit some of the reactive properties and surface transitions\nobserved in systems known to be catalytically active such as Pt (001).",
        "positive": "Antiferromagnetism, spin splitting, and spin-orbit interaction in MnTe: Hexagonal MnTe emerges as a critical component in designing magnetic quantum\nheterostructures, calling for a detailed study. After finding a suitable\ncombination of exchange-correlation functional and corrections, our study\nwithin {\\em ab initio} density functional theory uncovers an insulating state\nwith a preferred antiferromagnetic order. We compute the exchange interaction\nstrengths to estimate the antiferromagnetic ordering temperature via Monte\nCarlo calculations. Our calculations and symmetry analysis reveal a large spin\nsplitting in the system due to the antiferromagnetic order without considering\nspin-orbit interaction, except in the $k_x$-$k_y$ plane. Critically examining\nthe band dispersion and spin textures obtained from our calculations and\ncomparing them with an insightful symmetry analysis and analytical model, we\nconfirm a combined Rashba-Dresselhaus interaction in the $k_x$-$k_y$ plane,\naround the K point of the system. Finally, we find ferroelectricity in the\nsystem for a higher energy magnetic configuration. Our results and insights\nwould help design heterostructures of MnTe for technological applications."
    },
    {
        "anchor": "A Deep Learning Approach for Semantic Segmentation of Unbalanced Data in\n  Electron Tomography of Catalytic Materials: Heterogeneous catalysts possess complex surface and bulk structures,\nrelatively poor intrinsic contrast, and often a sparse distribution of the\ncatalytic nanoparticles (NPs), posing a significant challenge for image\nsegmentation, including the current state-of-the-art deep learning methods. To\ntackle this problem, we apply a deep learning-based approach for the\nmulti-class semantic segmentation of a $\\gamma$-Alumina/Pt catalytic material\nin a class imbalance situation. Specifically, we used the weighted focal loss\nas a loss function and attached it to the U-Net's fully convolutional network\narchitecture. We assessed the accuracy of our results using Dice similarity\ncoefficient (DSC), recall, precision, and Hausdorff distance (HD) metrics on\nthe overlap between the ground-truth and predicted segmentations. Our adopted\nU-Net model with the weighted focal loss function achieved an average DSC score\nof 0.96 $\\pm$ 0.003 in the $\\gamma$-Alumina support material and 0.84 $\\pm$\n0.03 in the Pt NPs segmentation tasks. We report an average boundary-overlap\nerror of less than 2 nm at the 90th percentile of HD for $\\gamma$-Alumina and\nPt NPs segmentations. The complex surface morphology of the $\\gamma$-Alumina\nand its relation to the Pt NPs were visualized in 3D by the deep\nlearning-assisted automatic segmentation of a large data set of high-angle\nannular dark-field (HAADF) scanning transmission electron microscopy (STEM)\ntomography reconstructions.",
        "positive": "Building Materials Genome from Ground-State Configuration to Engineering\n  Advance: Individual phases are commonly considered as the building blocks of\nmaterials. However, the accurate theoretical prediction of properties of\nindividual phases remains elusive. The top-down approach by decoding genomic\nbuilding blocks of individual phases from experimental observations is\nnon-unique. The density functional theory (DFT), as the state-of-the-art\nsolution of quantum mechanics, prescribes the existence of a ground-state\nconfiguration at zero K for a given system. It is self-evident that the\nground-state configuration alone is insufficient to describe a phase at finite\ntemperatures as symmetry-breaking non-ground-state configurations are excited\nstatistically at temperatures above zero K. Our multi-scale entropy approach\n(recently terms as Zentropy theory) postulates that the entropy of a phase is\ncomposed of the sum of the entropy of each configuration weighted by its\nprobability plus the configurational entropy among all configurations.\nConsequently, the partition function of each configuration in statistical\nmechanics needs to be evaluated by its free energy rather than total energy.\nThe combination of the ground- and non-ground-state configurations represents\nthe building blocks of materials and can quantitively predict free energy of\nindividual phases with the free energies of ground- and non-ground-state\nconfigurations predicted from DFT, plus all properties derived from free energy\nof individual phases."
    },
    {
        "anchor": "Conductivity of DNA probed by conducting-atomic force microscopy:\n  effects of contact electrode, DNA structure, surface interactions: We studied the electrical conductivity of DNA molecules with conducting\natomic force microscopy as a function of the chemical nature of the substrate\nsurfaces, the nature of the electrical contact, and the number of DNA molecules\n(from a few molecules, to ropes and large fibers containing up to ~ 106\nmolecules). Independent of the chemical nature of the surface (hydrophobic or\nhydrophilic, electrically neutral or charged), we find that DNA is highly\nresistive. From a large number of current-voltage curves measured at several\ndistance along the DNA, we estimate a conductivity of about 10-6-10-5 S.cm-1\nper DNA molecule. For single DNA molecules, this highly resistive behavior is\ncorrelated with its flattened conformation on the surface (reduced thickness,\n\\~0.5-1.5 nm, compared to its nominal value, ~2.4 nm). We find that\nintercalating an organic semiconductor buffer film between the DNA and the\nmetal electrode improves the reliability of the contact, while direct metal\nevaporation usually destroys the DNA and prevents any current measurements.\nAfter long exposure under vacuum or dry nitrogen, the conductivity strongly\ndecreases, leading to the conclusion that water molecules and ions in the\nhydration shell of the DNA play a major role.",
        "positive": "Thermal Annealing of High Dose P Implantation in 4H-SiC: In this work, we have studied the crystal defectiveness and doping activation\nsubsequent to ion implantation and post-annealing by using various techniques\nincluding photoluminescence (PL), Raman spectroscopy and transmission electron\nmicroscopy (TEM). The aim of this work was to test the effectiveness of double\nstep annealing to reduce the density of point defects generated during the\nannealing of a P implanted 4H-SiC epitaxial layer. The outcome of this work\nevidences that neither the first, 1 hour isochronal annealing at 1650 - 1700 -\n1750 {\\deg}C, nor the second one, at 1500 {\\deg}C for times between 4 hour and\n14 hour, were able to recover a satisfactory crystallinity of the sample and\nachieve dopant activations exceeding 1%."
    },
    {
        "anchor": "Positional Disorder, Spin-Orbit Coupling and Frustration in GaMnAs: We study the magnetic properties of metallic GaMnAs. We calculate the\neffective RKKY interaction between Mn spins using several realistic models for\nthe valence band structure of GaAs. We also study the effect of positional\ndisorder of the Mn on the magnetic properties. We find that the interaction\nbetween two Mn spins is anisotropic due to spin-orbit coupling within both the\nso-called spherical approximation and in the more realistic six band model. The\nspherical approximation strongly overestimates this anistropy, especially for\nshort distances between Mn ions. Using the obtained effective Hamiltonian we\ncarry out Monte Carlo simulations of finite and zero temperature magnetization\nand find that, due to orientational frustration of the spins, non-collinear\nstates appear in both valence band approximations for disordered, uncorrelated\nMn impurities in the small concentration regime. Introducing correlations among\nthe substitutional Mn positions or increasing the Mn concentration leads to an\nincrease in the remnant magnetization at zero temperature and an almost fully\npolarized ferromagnetic state.",
        "positive": "Preferential Forest-assembly of Single-Wall Carbon Nanotubes on\n  Low-energy Electron-beam Patterned Nafion Films: With the aid of low-energy (500 eV) electron-beam direct writing, patterns of\nperpendicularly-aligned Single-wall carbon nanotube (SWNT) forests were\nrealized on Nafion modified substrates via Fe3+ assisted self-assembly.\nInfrared spectroscopy (IR), atomic force microscopy (AFM) profilometry and\ncontact angle measurements indicated that low-energy electron-beam cleaved the\nhydrophilic side chains (-SO3H and C-O-C) of Nafion to low molecular byproducts\nthat sublimed in the ultra-high vacuum (UHV) environment exposing the\nhydrophobic Nafion backbone. Auger mapping and AFM microscopy affirmed that the\nexposed hydrophobic domains absorbed considerably less Fe3+ ions upon exposure\nto pH 2.2 aqueous FeCl3 solution, which yield considerably less FeO(OH)/FeOCl\nprecipitates (FeO(OH) in majority) upon washing with lightly basic DMF solution\ncontaining trace amounts of adsorbed moisture. Such differential deposition of\nFeO(OH)/FeOCl precipitates provided the basis for the patterned site-specific\nself-assembly of SWNT forests as demonstrated by AFM and resonance Raman\nspectroscopy."
    },
    {
        "anchor": "Structure and Magnetism in Mn Doped Zirconia: Density-functional Theory\n  Studies: Using the first-principles density-functional theory plan-wave\npseudopotential method, we investigate the structure and magnetism in 25% Mn\nsubstitutive and interstitial doped monoclinic, tetragonal and cubic ZrO2\nsystematically. Our studies show that the introduction of Mn impurities into\nZrO2 not only stabilizes the high temperature phase, but also endows ZrO2 with\nmagnetism. Based on the simple crystal field theory (CFT), we discuss the\norigination of magnetism in Mn doped ZrO2. Moreover, we discuss the effect of\nelectron donor on magnetic semiconductors, and the possibility as electronic\nstructure modulator.",
        "positive": "Electron carrier-mediated room temperature ferromagnetism in anatase\n  (Ti,Co)O2: Since the discovery of room temperature ferromagnetism in (Ti,Co)O2, the\nmechanism has been under discussion for a decade. Particularly, the central\nconcern has been whether or not the ferromagnetic exchange interaction is\nmediated by charge carriers like (Ga,Mn)As. Recent two studies on the control\nof ferromagnetism in anatase (Ti,Co)O2 at room temperature via electric field\neffect [Y. Yamada et al., Science 332, 1065 (2011)] and chemical doping [Y.\nYamada et al., Appl. Phys. Lett. 99, 242502 (2011)] indicate a principal role\nof electrons in the carrier-mediated exchange interaction. In this article, the\nauthors review fundamental properties of anatase (Ti,Co)O2 and discuss the\ncarrier mediated ferromagnetism."
    },
    {
        "anchor": "Descriptors of intrinsic hydrodynamic thermal transport: screening a\n  phonon database in a machine learning approach: Machine learning techniques are used to explore the intrinsic origins of the\nhydrodynamic thermal transport and to find new materials interesting for\nscience and engineering. The hydrodynamic thermal transport is governed\nintrinsically by the hydrodynamic scale and the thermal conductivity. The\ncorrelations between these intrinsic properties and harmonic and anharmonic\nproperties, and a large number of compositional (290) and structural (1224)\ndescriptors of 131 crystal compound materials are obtained, revealing some of\nthe key descriptors that determines the magnitude of the intrinsic hydrodynamic\neffects, most of them related with the phonon relaxation times. Then, a trained\nblack-box model is applied to screen more than 5000 materials. The results\nidentify materials with potential technological applications. Understanding the\nproperties correlated to hydrodynamic thermal transport can help to find new\nthermoelectric materials and on the design of new materials to ease the heat\ndissipation in electronic devices.",
        "positive": "Interpretation of micromorphic constitutive relations for porous\n  materials at the microscale via harmonic decomposition: Micromorphic theories became an established tool to model size effects in\nmaterials like dispersion, localization phenomena or (apparently) size\ndependent properties. However, the formulation of adequate constitutive\nrelations with its large number of constitutive relations and respective\nparameters hinders the usage of the full micromorphic theory, which has 18\nconstitutive parameters already in the isotropic linear elastic case. Although\nit is clear that these parameters are related to predicted size effects, the\nindividual meaning of single parameters has been rather unclear. The present\nwork tries to elucidate the interpretation of the constitutive relations and\ntheir parameters. For this purpose, a harmonic decomposition is applied to the\ngoverning equations of micromorphic theory. The harmonic modes are interpreted\nat the microscale using a homogenization method for a simple volume element\nwith spherical pore. The resulting boundary-value problem at the microscale is\nsolved analytically for the linear-elastic case using spherical harmonics\nresulting in closed-form expressions for all of the elastic 18 parameters.\nThese values are used to predict the size effect in torsion of slender foam\nspecimens. The predictions are compared with respective experimental results\nfrom literature."
    },
    {
        "anchor": "Soft X-ray Absorption Spectroscopy Study of Multiferroic Bi-substituted\n  Ba(1-x)Bi(x)Ti(0.9)Fe(0.1)O(3): The electronic structures of multiferroic oxides of\nBa(1-x)Bi(x)Ti(0.9)Fe(0.1)O(3) (0 < x < 0.12) have been investigated by\nemploying photoemission spectroscopy and soft x-ray absorption spectroscopy\n(XAS). The measured Fe and Ti 2p XAS spectra show that Ti ions are in the Ti4+\nstates for all x and that Fe ions are Fe2+-Fe3+ mixed-valent for x > 0. The\nvalence states of Fe ions are found to be nearly trivalent for x=0, and\ndecreases with increasing x from being nearly trivalent (v(Fe)~ 3) for x=0 to\nv(Fe)~ 2.6 for x=0.12. The valence states of both Ti and Ba ions do not change\nfor all x < 0.12. Based on the obtained valence states of Fe ions, the\nelectronic and magnetic properties of Ba(1-x)Bi(x)Ti(0.9)Fe(0.1)O(3) are\nexplored.",
        "positive": "Temperature and Pressure-driven Spin transitions and Piezochromism in a\n  Mn-based Hybrid Perovskite: Hybrid perovskites have been at the forefront of condensed matter research\nparticularly in context of device applications primarily in relation to\napplications in the field of solar cells. In this article, we demonstrate that\nseveral new functionalities may be added to the arsenal of hybrid perovskites,\nin terms of external stimuli driven spin transitions as well as piezochromism.\nAs an example, we study Dimethylammonium Manganese Formate (DMAMnF), a hybrid\nperovskite investigated quite extensively experimentally. We show by employing\nfirst principles DFT+U calculations with the aid of ab initio molecular\ndynamics calculations that DMAMnF shows temperature and pressure driven spin\ntransitions, from a low spin $S=1/2$ to a high spin $S=5/2$ state. This\ntransition is accompanied by a hysteresis, and we find that this hysteresis and\nthe transition temperature are quite close to room temperature, which is\ndesirable for device applications particularly in memory, display, and\nswitching devices. The operating pressure is a few GPa, which is accessible in\nstandard laboratory settings. We find that the cooperative behaviour showing up\nas hysteresis accompanying the transition is driven primarily by elastic\ninteractions, assisted by magnetic superexchange between Mn atoms. Last but not\nleast we demonstrate that the spin transition is associated with piezochromism\nwhich could also be important for applications."
    },
    {
        "anchor": "Comparative study of hybrid functionals applied to structural and\n  electronic properties of semiconductors and insulators: We present a systematic study that clarifies validity and limitation of\ncurrent hybrid functionals in density functional theory for structural and\nelectronic properties of various semiconductors and insulators. The three\nhybrid functionals, PBE0 by Perdew, Ernzerhof, and Becke, HSE by Heyd,\nSucseria, and Ernzerhof, and a long-range corrected (LC) functional, are\nimplemented in a well-established plane-wave-basis-set scheme combined with\nnorm-conserving pseudopotentials, thus enabling us to assess applicability of\neach functional on equal footing to the properties of the materials. The\nmaterials we have examined in this paper range from covalent to ionic materials\nas well as a rare-gas solid whose energy gaps determined by experiments are in\nthe range of 0.6 eV - 14.2 eV: i.e., Ge, Si, BaTiO$_3$, $\\beta$-GaN, diamond,\nMgO, NaCl, LiCl, Kr, and LiF. We find that the calculated bulk moduli by the\nhybrid functionals show better agreement with the experiments than the\ngeneralized gradient approximation (GGA) provides, whereas the calculated\nlattice constants by the hybrid functionals and GGA show comparable accuracy.\nThe calculated energy band gaps and the valence-band widths for the ten\nprototype materials show substantial improvement using the hybrid functional\ncompared with GGA. In particular, it is found that the band gaps of the ionic\nmaterials as well as the rare-gas solid are well reproduced by the LC-hybrid\nfunctional, whereas those of covalent materials are well described by the HSE\nfunctional. We also examine exchange effects due to short-range and long-range\ncomponents of the Coulomb interaction and propose an optimum recipe to the\nshort-range and long-range separation in treating the exchange energy.",
        "positive": "First-principles study of PbTiO$_3$ under uniaxial strains and stresses: The behavior of PbTiO$_3$ under uniaxial strains and stresses is investigated\nfrom first-principles calculations within density functional theory. We show\nthat irrespectively of the uniaxial mechanical constraint applied, the system\nkeeps a purely ferroelectric ground-state, with the polarization aligned either\nalong the constraint direction ($FE_z$ phase) or along one of the pseudo-cubic\naxis perpendicular to it ($FE_x$ phase). This contrasts with the cases of\nisotropic or biaxial mechanical constraints for which novel phases combining\nferroelectic and antiferrodistortive motions have been previously reported.\nUnder uniaxial strain, PbTiO$_3$ switched from a $FE_x$ ground state under\ncompressive strain to $FE_z$ ground-state under tensile strain, beyond a\ncritical strain $\\eta_{zz}^c \\approx +1$\\%. Under uniaxial stress, PbTiO$_3$\nexhibits either a $FE_x$ ground state under compression ($\\sigma_{zz} < 0$) or\na $FE_z$ ground state under tension ($\\sigma_{zz} > 0$). Here, however, an\nabrupt jump of the structural parameters is also predicted under both\ncompressive and tensile stresses at critical values $\\sigma_{zz} \\approx$ $+2$\nGPa and $- 8$ GPa. This behavior appears similar to that predicted under\nnegative isotropic pressure and might reveal practically useful to enhance the\npiezoelectric response in nanodevices."
    },
    {
        "anchor": "Anisotropy and magnetization reversal with chains of submicron-sized Co\n  hollow spheres: Magnetic properties with chains of hcp Co hollow spheres have been studied.\nThe diameter of the spheres ranges from 500 to 800 nm, with a typical shell\nthickness of about 60 nm. The shell is polycrystalline with an average\ncrystallite size of 20 to 35 nm. The blocking temperature determined by the\nzero-field-cooling MZFC(T) measurement at H = 90 Oe is about 325 K. The\ncorresponding effective anisotropy is determined as, Keff = 4.6*10^4 J/m^3. In\naddition, the blocking temperature and the effective anisotropy determined by\nthe analysis on HC(T) are 395 K and 5.7*10^4 J/m^3, respectively. The\nexperimentally determined anisotropy is smaller by one order of magnitude than\nthe magnetocrystalline anisotropy of the bulk hcp Co, which is about 3 to\n5*10^5 J/m^3. A further analysis on HC(T) shows that the magnetization reversal\nfollows a nucleation rotational mode with an effective switching volume, V* =\n2.3*10^3 nm^3. The corresponding effective diameter is calculated as 16.4 nm.\nIt is slightly larger than the coherence length of Co, about 15 nm. The\npossible reason for the much reduced magnetic anisotropy is discussed briefly.",
        "positive": "Disorder-dependent Li diffusion in $\\mathrm{Li_6PS_5Cl}$ investigated by\n  machine learning potential: Solid-state electrolytes with argyrodite structures, such as\n$\\mathrm{Li_6PS_5Cl}$, have attracted considerable attention due to their\nsuperior safety compared to liquid electrolytes and higher ionic conductivity\nthan other solid electrolytes. Although experimental efforts have been made to\nenhance conductivity by controlling the degree of disorder, the underlying\ndiffusion mechanism is not yet fully understood. Moreover, existing theoretical\nanalyses based on ab initio MD simulations have limitations in addressing\nvarious types of disorder at room temperature. In this study, we directly\ninvestigate Li-ion diffusion in $\\mathrm{Li_6PS_5Cl}$ at 300 K using\nlarge-scale, long-term MD simulations empowered by machine learning potentials\n(MLPs). To ensure the convergence of conductivity values within an error range\nof 10%, we employ a 25 ns simulation using a $5\\times5\\times5$ supercell\ncontaining 6500 atoms. The computed Li-ion conductivity, activation energies,\nand equilibrium site occupancies align well with experimental observations.\nNotably, Li-ion conductivity peaks when Cl ions occupy 25% of the 4c sites,\nrather than at 50% where the disorder is maximized. This phenomenon is\nexplained by the interplay between inter-cage and intra-cage jumps. By\nelucidating the key factors affecting Li-ion diffusion in\n$\\mathrm{Li_6PS_5Cl}$, this work paves the way for optimizing ionic\nconductivity in the argyrodite family."
    },
    {
        "anchor": "Strong influence of non-magnetic ligands on the momentum dependent spin\n  splitting in antiferromagnets: Recent studies have shown that the non-relativistic antiferromagnetic\nordering could generate momentum-dependent spin splitting analogous to the\nRashba effect, but free from the requirement of relativistic spin-orbit\ncoupling. Whereas the classification of such compounds can be illustrated by\ndifferent spin-splitting prototypes (SSTs) from symmetry analysis and density\nfunctional theory calculations, the significant variation in bonding and\nstructure of these diverse compounds representing different SSTs clouds the\nissue of how much of the variation in spin splitting can be traced back to the\nsymmetry-defined characteristics, rather to the underlining chemical and\nstructural diversity. The alternative model Hamiltonian approaches do not\nconfront the issues of chemical and structural complexity, but often consider\nonly the magnetic sublattice, dealing with the all-important effects of the\nnon-magnetic ligands via renormalizing the interactions between the magnetic\nsites. To this end we constructed a 'DFT model Hamiltonian' that allows us to\nstudy SSTs at approximate 'constant chemistry', while retaining the realistic\natomic scale structure including ligands. This is accomplished by using a\nsingle, universal magnetic skeletal lattice (Ni2+ ions in Rocksalt NiO) and\ndesigning small displacements of the non-magnetic (oxygen) sublattice which\nproduce, by design, the different SSTs magnetic symmetries. We show that (i)\neven similar crystal structures having very similar band structures can lead to\ncontrasting behavior of spin splitting vs. momentum, and (ii) even subtle\ndeformations of the non-magnetic ligand sublattice could cause a giant spin\nsplitting in AFM-induced SST. This is a paradigm shift relative to the\nconvention of modeling magnets without considering the non-magnetic ligand that\nmediate indirect magnetic interaction (e.g., super exchange).",
        "positive": "Thermal Transport in Polymers: A Review: In this article, we review thermal transport in polymers with different\nmorphologies from aligned fibers to bulk amorphous states. We survey early and\nrecent efforts in engineering polymers with high thermal conductivity by\nfabricating polymers with large-scale molecular alignments. The experimentally\nrealized extremely high thermal conductivity of polymer nanofibers are\nhighlighted, and understanding of thermal transport physics from molecular\nsimulations are discussed. We then transition to the discussion of bulk\namorphous polymers with an emphasize on the physics of thermal transport and\nits relation with the conformation of molecular chains in polymers. We also\ndiscuss the current understanding of how the chemistry of polymers would\ninfluence thermal transport in amorphous polymers and some limited, but\nimportant chemistry-structural-property relationships. Lastly, challenges,\nperspectives and outlook of this field are presented. We hope this review will\ninspire more fundamental and applied research in the polymer thermal transport\nfield to advance scientific understanding and engineering applications."
    },
    {
        "anchor": "Origin of Low Thermal Conductivity in Nuclear Fuels: Using a novel many-body approach, we report lattice dynamical properties of\nUO2 and PuO2 and uncover various contributions to their thermal conductivities.\nVia calculated Grueneisen constants, we show that only longitudinal acoustic\nmodes having large phonon group velocities are efficient heat carriers. Despite\nthe fact that some optical modes also show their velocities which are extremely\nlarge, they do not participate in the heat transfer due to their unusual\nanharmonicity. Ways to improve thermal conductivity in these materials are\ndiscussed.",
        "positive": "Optical Properties of Dilute CuAl$_{1-x}$Fe$_x$O$_2$ Delafossite Alloys: For powder samples of CuAl$_{1-x}$Fe$_x$O$_2$ ($x =$ 0, 0.01, 0.05, and 0.1),\nmeasured optical properties are compared with model simulations and phonon\nspectra are compared with simulations based on weighted dynamical matrix\napproach."
    },
    {
        "anchor": "Atomic-like behaviors and orbital-related Luttinger liquid in carbon\n  nano-peapod quantum dots: We report influence of encapsulated C60 molecules on electron transport in\ncarbon-nanotube peapod quantum dots. We find atomic-like behaviors with doubly\ndegenerate electronic levels, which exist only around ground states, by single\nelectron spectroscopy measured at low back-gate voltages (Vbg). Correlation\nwith presence of nearly free electrons (NFEs) unique to the peapods is\ndiscussed. Moreover, we find anomalously high values of power a observed in\npower laws in conductance versus energy relationships, which are strongly\nassociated with the doubly degenerate levels. It is revealed that the powers\noriginate from Tomonaga-Luttinger liquid via the occupied doubly degenerate\nlevels. Our observations clarify that the encapsulated C60 molecules form\ndoubly degenerate levels only at ground state in peapod quantum dots and do not\neliminate a ballistic charge transport.",
        "positive": "Thallium under extreme compression: We present a combined theoretical and experimental study of the high-pressure\nbehavior of thallium. X-ray diffraction experiments have been carried out at\nroom temperature up to 125 GPa using diamond-anvil cells, nearly doubling the\npressure range of previous experiments. We have confirmed the hcp-fcc\ntransition at 3.5 GPa and determined that the fcc structure remains stable up\nto the highest pressure attained in the experiments. In addition, HP-HT\nexperiments have been performed up to 8 GPa and 700 K by using a combination of\nx-ray diffraction and a resistively heated diamond-anvil cell. Information on\nthe phase boundaries is obtained, as well as crystallographic information on\nthe HT bcc phase. The equation of state for different phases is reported. Ab\ninitio calculations have also been carried out considering several potential\nhigh-pressure structures. They are consistent with the experimental results and\npredict that, among the structures considered in the calculations, the fcc\nstructure of thallium is stable up to 4.3 TPa. Calculations also predict the\npost-fcc phase to have a close-packed orthorhombic structure above 4.3 TPa."
    },
    {
        "anchor": "Ultrafast photothermoelectric effect in Dirac semimetallic Cd3As2\n  revealed by terahertz emission: The thermoelectric effects of topological semimetals have attracted\ntremendous research interest because many topological semimetals are excellent\nthermoelectric materials and thermoelectricity serves as one of their most\nimportant potential applications. In this work, we reveal the transient\nphotothermoelectric response of Dirac semimetallic Cd3As2, namely the\nphoto-Seebeck effect and photo-Nernst effect, by studying the terahertz (THz)\nemission from the transient photocurrent induced by these effects. Our\nexcitation polarization and power dependence confirm that the observed THz\nemission is due to photothermoelectric effect instead of other nonlinear\noptical effect. Furthermore, when a weak magnetic field (~0.4 T) is applied,\nthe response clearly indicates an order of magnitude enhancement on transient\nphotothermoelectric current generation compared to the photo-Seebeck effect.\nSuch enhancement supports an ambipolar transport nature of the photo-Nernst\ncurrent generation in Cd3As2. These results highlight the enhancement of\nthermoelectric performance can be achieved in topological Dirac semimetals\nbased on the Nernst effect, and our transient studies pave the way for\nthermoelectric devices applicable for high field circumstance when\nnonequilibrium state matters. The large THz emission due to highly efficient\nphotothermoelectric conversion is comparable to conventional semiconductors\nthrough optical rectification and photo-Dember effect.",
        "positive": "Search for the magnetocaloric effect in multiferroics oxides: In this paper, we report on the magnetocaloric properties of some selected\nmultiferroic oxides, namely HoMn2O5 and La2(Ni,Co)MnO6 compounds which exhibit\ntransition points from 10K up to almost room temperature. In order to avoid\ngrain boundary effects and structural inhomogeneity observed frequently in\npolycrystalline samples, only single crystals were considered for this study."
    },
    {
        "anchor": "Fermi-level pinning in ErAs nanoparticles embedded in III-V\n  semiconductors: Embedding rare-earth pnictide (RE-V) nanoparticles into III-V semiconductors\nenables unique optical, electrical, and thermal properties, with applications\nin THz photoconductive switches, tunnel junctions, and thermoelectric devices.\nDespite the high structural quality and control over growth, particle size, and\ndensity, the underlying electronic structure of these nanocomposite materials\nhas only been hypothesized. Basic questions about the metallic or\nsemiconducting nature of the nanoparticles (that are typically < 3 nm in\ndiameter) have remained unanswered. Using first-principles calculations, we\ninvestigated the structural and electronic properties of ErAs nanoparticles in\nAlAs, GaAs, InAs, and their alloys. Formation energies of the ErAs\nnanoparticles with different shapes and sizes (i.e., from cubic to spherical,\nwith 1.14 nm, 1.71 nm, and 2.28 nm diameters) show that spherical nanoparticles\nare the most energetically favorable. As the diameter increases, the Fermi\nlevel is lowered from near the conduction band to the middle of the gap. For\nthe lowest energy nanoparticles, the Fermi level is pinned near the mid-gap, at\nabout 0.8 eV above the valence band in GaAs and about 1.2 eV in AlAs, and it is\nresonant in the conduction band in InAs. Our results show that the Fermi level\nis pinned on an absolute energy scale once the band alignment at AlAs/GaAs/InAs\ninterfaces is considered, offering insights into the rational design of these\nnanocomposite materials.",
        "positive": "New Methods for Calculating the Free Energy of Charged Defects in Solid\n  Electrolytes: A methodology for calculating the contribution of charged defects to the\nconfigurational free energy of an ionic crystal is introduced. The\ntemperature-independent Wang-Landau Monte Carlo technique is applied to a\nsimple model of a solid electrolyte, consisting of charged positive and\nnegative defects on a lattice. The electrostatic energy is computed on lattices\nwith periodic boundary conditions, and used to calculate the density of states\nand statistical-thermodynamic potentials of this system. The free energy as a\nfunction of defect concentration and temperature is accurately described by a\nregular solution model up to concentrations of 10% of defects, well beyond the\nrange described by the ideal solution theory.\n  The approach, supplemented by short-ranged terms in the energy, is proposed\nas an alternative to free-energy methods that require a number of simulations\nto be carried out over a range of temperatures."
    },
    {
        "anchor": "Interplay between the magnetic anisotropy contributions of Cobalt\n  nanowires: We report on the magnetic properties and the crystallographic structure of\nthe cobalt nanowire arrays as a function of their nanoscale dimensions. X-ray\ndiffraction measurements show the appearance of an in-plane HCP-Co phase for\nnanowires with 50 nm diameter, suggesting a partial reorientation of the\nmagnetocrystalline anisotropy axis along the membrane plane with increasing\npore diameter. No significant changes in the magnetic behavior of the nanowire\nsystem are observed with decreasing temperature, indicating that the effective\nmagnetoelastic anisotropy does not play a dominant role in the remagnetization\nprocesses of individual nanowires. An enhancement of the total magnetic\nanisotropy is found at room temperature with a decreasing nanowire\ndiameter-to-length ratio (d/L), a result that is quantitatively analyzed on the\nbasis of a simplified shape anisotropy model.",
        "positive": "Energy Gap and the Ideal Glass as a Defective Crystal: A Lattice Model\n  of Monatomic Systems: We use the cell model to justify the use of a lattice model to study the\nideal glass transition. Based on empirical evidence and several previous exact\ncalculations, we hypothesize that there exists an energy gap between the lowest\npossible energy of a glass (the ideal glass IG) and the crystal (CR). The gap\nis due to the presence of strongly correlated excitations with respect to the\nideal CR; thus, one can treat IG as a highly defective crystal. We argue that\nan excitation in IG requires energy that increases logarithmically with the\nsize of the system; as a consequence, we prove that IG must emerge at a\npositive temperature T_{K}. We propose an antiferromagnetic Ising model on a\nlattice to model liquid-crystal transition in a simple fluid or a binary\nmixture, which is then solved exactly on a recursive (Husimi) lattice to\ninvestigate the ideal glass transition, the nature of defects in the\nsupercooled liquid and CR analytically, and the effects of competing\ninteractions on the glass transition. The calculation establishes the gap. The\nlattice entropy of the supercooled liquid vanishes at a positive temperature\nT_{K}>0, where IG emerges but where CR has a positive entropy. The macrostate\nIG is in a particular and unique disordered microstate at T_{K}, just as the\nideal CR is in a perfectly ordered microstate at absolute zero. This explains\nwhy it is possible for CR to have a higher entropy at T_{K} than IG. The\ndemonstration here of an entropy crisis in monatomic systems along with\npreviously known results strongly suggests that the entropy crisis first noted\nby Kauzmann and demonstrated by Gibbs and DiMarzio in long polymers appears to\nbe ubiquitous in all supercooled liquids."
    },
    {
        "anchor": "Interface Probing by Dielectric Frequency Dispersion in Carbon\n  Nanocomposites: Interfaces remain one of the major issues in limiting the understanding and\ndesigning polymer nanocomposites due to their complexity and pivotal role in\ndetermining the ultimate composites properties. In this study, we take\nmulti-walled carbon nanotubes/silicone rubber nanocomposites as a\nrepresentative example, and have for the first time studied the correlation\nbetween high-frequency dielectric dispersion and static/dynamic interfacial\ncharacteristics. We have found that the interface together with other\nmeso-structural parameters (volume fraction, dispersion, agglomeration) play\ndecisive role in formulating the dielectric patterns. The calculation of the\nrelaxation times affords the relative importance of interfacial polarization to\ndipolar polarization in resultant dielectric relaxation. Dielectric\nmeasurements coupled with cyclic loading further reveals the remarkable\ncapability of dielectric frequency dispersion in capturing the evolution of\ninterfacial properties, such as a particular interface reconstruction process\noccurred to the surfactant-modified samples. All these results demonstrate that\nhigh-frequency dielectric spectroscopy is instrumental to probing both static\nand dynamic meso-structural characteristics, especially effective for the\ncomposites with relative weak interfaces which remains a mission impossible for\nmany other techniques. The insights provided here based on the analyses of\ndielectric frequency dispersion will pave the way for optimized design and\nprecise engineering of meso-structure in polymer nanocomposites.",
        "positive": "Electronic and magnetic properties of Lu and LuH$_2$: Clarifying the electronic and magnetic properties of lutetium, lutetium\ndihydride, and lutetium oxide is very helpful to understand the emergent\nphenomena in lutetium-based compounds (such as room-temperature\nsuperconductivity). However, this kind of study is still scarce at present.\nHere, we report on the electronic and magnetic properties of lutetium metals,\nlutetium dihydride powders, and lutetium oxide powders. Crystal structures and\nchemical compositions of these samples were characterized by X-ray diffraction\nand X-ray photoemission spectroscopy, respectively. Electrical transport\nmeasurements show that the resistance of lutetium has a linear behavior\ndepending on temperature, whereas the resistance of lutetium dihydride powders\nis independent of temperature. More interestingly,\nparamagnetism-ferromagnetism-spin glass transitions were observed at near 240\nand 200 K, respectively, in lutetium metals. Our work uncovered the complex\nmagnetic properties of Lu-based compounds."
    },
    {
        "anchor": "Resonance behavior of the defect-induced Raman mode of single-chirality\n  enriched carbon nanotubes: We present a resonance Raman study of the disorder-induced D mode in a sample\nhighly enriched with semiconducting (9,7) single-walled carbon nanotubes in the\nexcitation energy range of 1.49 - 2.05 eV. The intensity of the D mode shows a\nresonance behavior near the optical transition of the (9,7) tube. The\nwell-known dispersion of the D-mode frequency, on the other hand, is not\nobserved at the resonance, but only above a certain excitation energy. We\nexplain our results by numerical simulations of the D-mode spectra.",
        "positive": "Theory of transformation-mediated twinning: High-density and nanosized deformation twins in face-centered cubic\n(fcc)materials can effectively improve the combination of strength and\nductility. However, the microscopic dislocation mechanisms enabling a high\ntwinnability remain elusive. Twinning usually occurs via continuous nucleation\nand gliding of twinning partial dislocations on consecutive close-packed atomic\nplanes. Here we unveil a completely different twinning mechanism being active\nin metastable fcc materials. The transformation-mediated twinning (TMT) is\nfeatured by a preceding displacive transformation from the fcc phase to the\nhexagonal close-packed (hcp) one, followed by a second-step transformation from\nthe hcp phase to the fcc twin. The nucleation of the intermediate hcp phase is\ndriven by the thermodynamic instability and the negative stacking fault energy\nof the metastable fcc phase. The intermediate hcp structure is characterized by\nthe easy slips of Shockley partial dislocations on the basal planes, which\nleads to both fcc and fcc twin platelets during deformation, creating more twin\nboundaries and further enhancing the prosperity of twins. The disclosed\nfundamental understanding of the complex dislocation mechanism of deformation\ntwinning in metastable alloys paves the road to design novel materials with\noutstanding mechanical properties."
    },
    {
        "anchor": "Impact of carrier localization on recombination in InGaN quantum wells\n  and the efficiency of nitride light-emitting diodes: insights from theory and\n  numerical simulations: We examine the effect of carrier localization due to random alloy\nfluctuations on the radiative and Auger recombination rates in InGaN quantum\nwells as a function of alloy composition, crystal orientation, carrier density,\nand temperature. Our results show that alloy fluctuations reduce individual\ntransition matrix elements by the separate localization of electrons and holes,\nbut this effect is overcompensated by the additional transitions enabled by\ntranslational symmetry breaking and the resulting lack of momentum\nconservation. Hence, we find that localization increases both radiative and\nAuger recombination rates, but that Auger recombination rates increase by one\norder of magnitude more than radiative rates. Furthermore, we demonstrate that\nlocalization has an overall detrimental effect on the efficiency-droop and\ngreen-gap problems of InGaN LEDs.",
        "positive": "Interband and polaronic excitations in YTiO3 from first principles: YTiO3, as a prototypical Mott insulator, has been the subject of numerous\nexperimental investigations of its electronic structure. The onset of\nabsorption in optical conductivity measurements has generally been interpreted\nto be due to interband transitions at the fundamental gap. Here we re-examine\nthe electronic structure of YTiO3 using density functional theory with either a\nHubbard correction (DFT+U) or a hybrid functional. Interband transitions turn\nout to be much higher in energy than the observed onset of optical absorption.\nHowever, in case of $p$-type doping, holes tend to become self-trapped in the\nform of small polarons, localized on individual Ti sites. Exciting electrons\nfrom the occupied lower Hubbard band to the small-polaron state then leads to\nbroad infrared absorption, consistent with the onset in the experimental\noptical conductivity spectra."
    },
    {
        "anchor": "Site occupation of indium and jump frequencies of cadmium in FeGa3: Perturbed angular correlation (PAC) measurements using the In-111 probe were\ncarried out on FeGa3 as part of a broader investigation of indium site\noccupation and cadmium diffusion in intermetallic compounds. One PAC signal was\nobserved with hyperfine parameters w1 = 513.8(1) Mrad/s and eta = 0.939(2) at\nroom temperature. By comparison with quadrupole frequencies observed in PAC\nmeasurements on isostructural RuIn3, it was determined that indium occupies\nonly the 8j site in the FeGa3 structure, denoted Ga(2) below because two out of\nthe three Ga sites have this point symmetry. PAC spectra at elevated\ntemperature exhibited damping characteristic of electric field gradients (EFGs)\nthat fluctuate as Cd probes jump among Ga(2) sites within the lifetime of the\nexcited PAC level. A stochastic model for the EFG fluctuations based on four\nconceivable, single-step jump-pathways connecting one Ga(2) site to neighboring\nGa(2) sites was developed and used to fit PAC spectra. The four pathways lead\nto two observable EFG reorientation rates, and these reorientation rates were\nfound to be strongly dependent on EFG orientation. Calculations using density\nfunctional theory were used to reduce the number of unknowns in the model with\nrespect to EFG orientation. This made it possible to determine with reasonable\nprecision the total jump rate of Cd among Ga(2) sites that correspond to a\nchange in mirror plane orientation of site-symmetry. This total jump rate was\nfound to be thermally activated with an activation enthalpy of 1.8(1) eV.",
        "positive": "Optical properties of anatase and rutile TiO2 studied by GGA+U: The optical properties of thermally annealed TiO2 samples depend on their\npreparation process, and the TiO2 thin films usually exist in the form of\nanatase or rutile or the mixture of the two phases. The electronic structures\nand optical properties of anatase and rutile TiO2 are calculated by means of\nFirst-principles generalized gradient approximation (GGA) +U approach. By\nIntroducing the Coulomb interactions on 3d orbitals of Ti atom (Ud) and 2p\norbitals of O atom (Up), we can reproduce the experimental values of the band\ngap. The optical properties of anatase and rutile TiO2 are obtained by means of\nGGA+U method, well agreeing with experimental results and other theoretical\ndata. Further we present the comparison of the electronic structure,\nbirefringence and anisotropy between the two phases of TiO2."
    },
    {
        "anchor": "Atomistic insights into the mixed-alkali effect in phosphosilicate\n  glasses: In recent years, tailoring the properties of bioactive glasses through\ncompositional design have become the subject of widespread interest for their\nuse in medical application, e.g., tissue regeneration. Understanding the mixed\nalkali effect (MAE) in oxide glasses is of fundamental importance for tailoring\nthe glass compositions to control the mobility of ions and, therefore, the\nglass properties that depend on it, such as ion release, glass transition\ntemperature, and ionic conductivity. However, most of the previously designed\nbioactive glasses were based on trial-and-error, which is due to the complex\nglass structure that is non-trivial to analyze and, thus, the lack of a clear\npicture of the glass structure at short- and medium-range order. Accordingly,\nwe use molecular dynamics simulations to study whether using the MAE can\ncontrol the bioactivity and properties of 45S5 glass and its structural\norigins. We showed that the network connectivity, a structural parameter often\nused to access the bioactivity of silicate glasses, does not change with Na\nsubstitution with Li or K. On the contrary, the elastic moduli showed a strong\ndependence on the type of the modifier, as they increased with increasing mean\nfield strength. Similarly, the mobility of the glass elements was significantly\naffected by the type of modifier used to substitute Na. The change of the\nproperties is further discussed and explained using changes at the short- and\nmedium-range structure by giving evidence of previous experimental findings.\nFinally, we highlight the origin of the non-existence of the MAE, the effect of\nthe modifier on the bioactivity of the glasses, the importance of dynamical\ndescriptors in predicting the bioactivity of oxide glasses, and we provide the\nnecessary insights, at the atomic scale, needed for further development of\nbioactive glasses.",
        "positive": "Graphene on metal surface: gap opening and n-doping: Graphene grown on metal surface, Cu(111), with a boron nitride(BN) buffer\nlayer is studied for the first time. Our first-principles calculations reveal\nthat charge is transferred from the copper substrate to graphene through the BN\nbuffer layer which results in a n-doped graphene in the absence of a gate\nvoltage. More importantly, a gap of 0.2 eV which is comparable to that of a\ntypical narrow gap semicondutor opens just 0.5 eV below the Fermi-level at the\nDirac point. The Fermi-level can be easily shifted inside this gap to make\ngraphene a semiconductor which is crucial for graphene-based electronic\ndevices. A graphene based p-n junction can be realized with graphene eptaxially\ngrown on metal surface."
    },
    {
        "anchor": "Laser written junctionless dual in-plane-gate thin-film transistors with\n  AND Logic function: A simple laser scribing process has been developed to fabricate low-voltage\njunctionless in-plane-gate thin-film transistors (TFTs) arrays without any mask\nand photolithography. Such junctionless TFTs feature that the channel and the\nsource/drain electrodes are of the same indium-tin-oxide films without any\nintentional source/drain junction deposition process. Effective field-effect\nmodulation of the drain current has been realized on such in-plane-gate device\nwith a field-effect mobility of ~12.6cm2/Vs. At last, AND gate logic function\nwas demonstrated on dual in-plane-gate device.",
        "positive": "Dynamical scaling and isotope effect in temporal evolution of mesoscopic\n  structure during hydration of cement: The evolution of mesoscopic structure for cement-water mixtures turning into\ncolloidal gels remains far from being understood. Recent neutron scattering\ninvestigations (Phys. Rev. Lett. 93, 255704 (2004); Phys. Rev. B. 72, 224208\n(2005); Phys. Rev. B. 82, 064203 (2010)),, reveal the role of hydrogen bond in\ntemporal evolution of the mesoscopic structure during hydration of cement which\nis the most consumed synthetic material. The present neutron scattering\ninvestigation on hydration of cement with a mixture of light and heavy water\npoints to incomprehensibility of the temporal evolution of the mesoscopic\nstructure in terms of earlier observations on hydration with pure light or\nheavy water. Unlike in the case of hydration with light water, disagreement has\nbeen observed with the hypothesis of dynamical scaling for hydration of cement\nwith a mixture of the two types of water. The dynamics of evolution of the\nmesoscopic structure has been observed to be nonlinear in regard to the\ncomposition of hydration medium."
    },
    {
        "anchor": "Random barrier double-well model for resistive switching in tunnel\n  barriers: The resistive switching phenomenon in MgO-based tunnel junctions is\nattributed to the effect of charged defects inside the barrier. The presence of\nelectron traps in the MgO barrier, that can be filled and emptied, locally\nmodifies the conductance of the barrier and leads to the resistive switching\neffects. A double-well model for trapped electrons in MgO is introduced to\ntheoretically describe this phenomenon. Including the statistical distribution\nof potential barrier heights for these traps leads to a power-law dependence of\nthe resistance as a function of time, under a constant bias voltage. This model\nalso predicts a power-law relation of the hysteresis as a function of the\nvoltage sweep frequency. Experimental transport results strongly support this\nmodel and in particular confirm the expected power laws dependencies of\nresistance. They moreover indicate that the exponent of these power laws varies\nwith temperature as theoretically predicted.",
        "positive": "Exchange-dominated Standing Spin Wave Excitations under microwave\n  irradiation in Ni80Fe20 Thin Films: We investigated the microwave-assisted DC voltages of ferromagnetic\nresonances and exchangedominated standing spin wave excitations in two\ndifferent in-plane magnetized permalloy thin films via homodyne detection. The\nline shapes of ferromagnetic resonance spectra and the dispersion curves of\nferromagnetic resonance and standing spin wave are in agreement of previous\nstudies, while further investigations of DC voltage spectra for these two\nexcitations reveal that 1. unlike ferromagnetic resonance signals, the\nanti-symmetrical line shapes of standing spin wave excitations are not depend\non the electromagnetic relative phase of assisted microwave, and 2. linewidths\nof their DC voltage spectra are distinct. The complicated spin dynamics of\nstanding spin wave is consequently discussed by applying\nLandau-Lifshitz-Gilbert equation in term of exchange interaction."
    },
    {
        "anchor": "Mechanistic Data Science for Modeling and Design of Aerospace Composite\n  Materials: Polymer matrix composites exhibit remarkable lightweight and high strength\nproperties that make them attractive for aerospace applications. Constituents'\nmaterials such as advanced polymers and fibers or fillers with their\nhierarchical structure embed these exceptional properties to the composite\nmaterials. This hierarchical structure in multiple length scales provides an\nopportunity for designing the composite materials for optimized properties.\nHowever, the high dimensional design space for the constituents' materials and\narchitectures choice of the composites makes it a challenging design problem.\nTo tackle this high dimensional design space, a systematic, efficient approach\nnamed mechanistic data science framework is proposed in this work to identify\nthe governing mechanisms of materials systems from the limited available data\nand create a composite knowledge database. Our composite knowledge database\ncomprises the knowledge of polymers at the nanoscale with nano reinforcement,\nthe unidirectional structure at the microscale, and woven structure at\nmesoscale mechanisms that can be further used for the part scale composite\ndesign and analysis. The mechanistic data science framework presented in this\nwork can be further extended to other materials systems that will provide the\nmaterials designer with the necessary tools to evaluate a new materials system\ndesign rapidly.",
        "positive": "Automatic graph representation algorithm for heterogeneous catalysis: One of the most appealing aspects of machine learning for material design is\nits high throughput exploration of chemical spaces, but to reach the ceiling of\nML-aided exploration, more than current model architectures and processing\nalgorithms are required. New architectures such as Graph Neural Networks (GNNs)\nhave seen significant research investments recently. For heterogeneous\ncatalysis, defining substrate intramolecular bonds and adsorbate/substrate\nintermolecular bonds is a time-consuming and challenging process. Before\napplying a model, dataset pre-processing, node/bond descriptor design, and\nspecific model constraints have to be considered. In this work, a framework\ndesigned to solve these issues is presented in the form of an automatic graph\nrepresentation algorithm (AGRA) tool to extract the local chemical environment\nof metallic surface adsorption sites is presented. This tool is able to gather\nmultiple adsorption geometry datasets composed of different systems and combine\nthem into a single model. To show AGRA's excellent transferability and reduced\ncomputational cost compared to other graph representation methods, it was\napplied to 5 different catalytic reaction datasets and benchmarked against the\nOpen Catalyst Projects (OCP) graph representation method. The two ORR datasets\nwith O/OH adsorbates obtained 0.053 eV RMSD when combined together, whereas the\nthree CO2RR datasets with CHO/CO/COOH obtained an average performance of 0.088\neV RMSD. To further display the algorithm's versatility and extrapolation\nability, a model was trained on a subset combination of all 5 datasets with an\nRMSD of 0.105 eV. This universal model was then used to predict a wide range of\nadsorption energies and an entirely new ORR catalyst system and then verified\nthrough Density Functional Theory calculations"
    },
    {
        "anchor": "Nonempirical Density Functionals Investigated for Jellium:\n  Spin-Polarized Surfaces, Spherical Clusters, and Bulk Linear Response: Earlier tests show that the Tao-Perdew-Staroverov-Scuseria (TPSS)\nnonempirical meta-generalized gradient approximation (meta-GGA) for the\nexchange-correlation energy yields more accurate surface energies than the\nlocal spin density (LSD) approximation for spin-unpolarized jellium. In this\nstudy, work functions and surface energies of a jellium metal in the presence\nof ``internal'' and external magnetic fields are calculated with LSD,\nPerdew-Burke-Ernzerhof (PBE) GGA, and TPSS meta-GGA and its predecessor, the\nnearly nonempirical Perdew-Kurth-Zupan-Blaha (PKZB) meta-GGA, using\nself-consistent LSD orbitals and densities. The results show that: (i) For\nnormal bulk densities, the surface correlation energy is the same in TPSS as in\nPBE, as it should be since TPSS strives to represent a self-correlation\ncorrection to PBE; (ii) Normal surface density profiles can be scaled uniformly\nto the low-density or strong-interaction limit, and TPSS provides an estimate\nfor that limit that is consistent with (but probably more accurate than) other\nestimates; (iii) For both normal and low densities, TPSS provides the same\ndescription of surface magnetism as PBE, suggesting that these approximations\nmay be generally equivalent for magnetism. The energies of jellium spheres with\nup to 106 electrons are calculated using density functionals and compared to\nthose obtained with Diffusion Quantum Monte Carlo data, including our estimate\nfor the fixed-node correction. Finally we calculate the linear response of bulk\njellium using these density functionals, and find that not only LSD but also\nPBE GGA and TPSS meta-GGA yield a linear-response in good agreement with that\nof the Quantum Monte Carlo method, for wavevectors of the perturbing external\npotential up to twice the Fermi wavevector.",
        "positive": "Shack-Hartmann wavefront sensing: A new approach to time-resolved\n  measurement of stress intensity during dynamic fracture of small brittle\n  specimens: The stress intensity factor is important for understanding crack initiation\nand propagation. Because it cannot be measured directly, the characterization\nof the stress intensity factor relies on the measurement of deformation around\na crack tip. Such measurements are challenging for dynamic fracture of brittle\nmaterials where the deformation is small and the crack tip velocity can be high\n(>1 km/s). Digital gradient sensing (DGS) is capable of full-field measurement\nof surface deformation with sub-microsecond temporal resolution, but it is\nlimited to centimeter-scale specimens and has a spatial resolution of only\n$\\sim 1$mm. This limits its ability to measure deformations close to the crack\ntip. Here, we demonstrate the potential of Shack-Hartmann wavefront sensing\n(SHWFS), as an alternative to DGS, for measuring surface deformation during\ndynamic brittle fracture of millimeter-scale specimens. Using an commercial\nglass ceramic as an example material, we demonstrate the capability of SHWFS to\nmeasure the surface slope evolution induced by a propagating crack on\nmillimeter-scale specimens with a micrometer-scale spatial resolution and a\nsub-microsecond temporal resolution. The SHWFS apparatus has the additional\nadvantage of being physically more compact than a typical DGS apparatus. We\nverify our SHWFS measurements by comparing them with analytical predictions and\nphase-field simulations of the surface slope around a crack tip. Then, fitting\nthe surface slope measurements to the asymptotic crack-tip field solution, we\nextract the evolution of the apparent stress intensity factor associated with\nthe propagating crack tip. We conclude by discussing potential future\nenhancements of this technique and how its compactness could enable the\nintegration with other characterization techniques including x-ray\nphase-contrast imaging (XPCI) toward a multi-modal characterization."
    },
    {
        "anchor": "A two-scale model for sheared fault gouge: Competition between\n  macroscopic disorder and local viscoplasticity: We develop a model for sheared gouge layers that accounts for the local\nincrease in temperature at the grain contacts during sliding. We use the shear\ntransformation zone (STZ) theory, a statistical thermodynamic theory, to\ndescribe irreversible macroscopic plastic deformations due to local\nrearrangements of the gouge particles. We track the temperature evolution at\nthe grain contacts using a one dimensional heat diffusion equation. At low\ntemperatures, the strength of the asperities is limited by the flow strength,\nas predicted by dislocation creep models. At high temperatures, some of the\nconstituents of the grains may melt leading to the degradation of the asperity\nstrength. Our model predicts a logarithmic rate dependence of the steady state\nshear stress in the quasi-static regime. In the dense flow regime the\nfrictional strength decreases rapidly with increasing slip rate due to the\neffect of thermal softening at the granular interfaces. The transient response\nfollowing a step in strain rate includes a direct effect and a following\nevolution effect, both of which depend on the magnitude and direction of the\nvelocity step. In addition to frictional heat, the energy budget includes an\nadditional energy sink representing the fraction of external work consumed in\nincreasing local disorder. The model links low-speed and high-speed frictional\nresponse of gouge layers, and provides an essential ingredient for multiscale\nmodeling of earthquake ruptures with enhanced coseismic weakening.",
        "positive": "Dipole-quadrupole interactions and the nature of phase III of compressed\n  hydrogen: A new class of strongly infrared active structures is identified for phase\nIII of compressed molecular H2 by constant-pressure ab initio molecular\ndynamics and density-functional perturbation calculations. These are planar\nquadrupolar structures obtained as a distortion of low-pressure quadrupolar\nphases, after they become unstable at about 150 GPa due to a zone-boundary soft\nphonon. The nature of the II-III transition and the origin of the IR activity\nare rationalized by means of simple electrostatics, as the onset of a\nstabilizing dipole-quadrupole interaction."
    },
    {
        "anchor": "Optical properties of dense lithium in electride phases by\n  first-principles calculations: The metal-semiconductor-metal transition in dense lithium is considered as an\narchetype of interplay between interstitial electron localization and\ndelocalization induced by compression, which leads to exotic electride phases.\nIn this work, the dynamic dielectric response and optical properties of the\nhigh-pressure electride phases of cI16, oC40 and oC24 in lithium spanning a\nwide pressure range from 40 to 200 GPa by first-principles calculations are\nreported. Both interband and intraband contribution to the dielectric function\nare deliberately treated with the linear response theory. One intraband and two\ninterband plasmons in cI16 at 70 GPa induced by a structural distortion at 2.1,\n4.1, and 7.7 eV are discovered, which make the reflectivity of this weak\nmetallic phase abnormally lower than the insulating phase oC40 at the\ncorresponding frequencies. More strikingly, oC24 as a reentrant metallic phase\nwith higher conductivity becomes more transparent than oC40 in infrared and\nvisible light range due to its unique electronic structure around Fermi\nsurface. An intriguing reflectivity anisotropy in both oC40 and oC24 is\npredicted, with the former being strong enough for experimental detection\nwithin the spectrum up to 10 eV. The important role of interstitial localized\nelectrons is highlighted, revealing diversity and rich physics in electrides.",
        "positive": "Comparing theoretical predictions of radiation-free velocities of edge\n  dislocations to molecular dynamics simulations: Transonic defect motion is of interest for high strain-rate plastic\ndeformation as well as for crack propagation. Ever since Eshelby's 1949\nprediction in the isotropic limit of a 'radiation-free' transonic velocity\n$v_\\text{RF}=\\sqrt{2}c_{\\textrm{T}}$, where shock waves are absent, there has\nbeen speculation about the significance of radiation-free velocities for defect\nmobility. Here, we argue that they do not play any significant role in\ndislocation dynamics in metals, based on comparing theoretical predictions of\nradiation-free velocities for transonic edge dislocations with molecular\ndynamics simulations for two face-centered cubic (FCC) metals: Cu, which has no\nradiation-free states, and Ag, which does."
    },
    {
        "anchor": "Atomic layer deposition of Y2O3 on h-BN for a gate stack in graphene\n  FETs: The combination of h-BN and high-k dielectrics is required for a top gate\ninsulator in miniaturized graphene field-effect transistors because of the low\ndielectric constant of h-BN. We investigated the deposition of Y2O3 on h-BN\nusing atomic layer deposition. The deposition of Y2O3 on h-BN was confirmed\nwithout any buffer layer. An increase in the deposition temperature reduced the\nsurface coverage. The deposition mechanism could be explained by the\ncompetition between the desorption and adsorption of the Y precursor on h-BN\ndue to the polarization. Although a full surface coverage was difficult to\nachieve, the use of an oxidized metal seeding layer on h-BN resulted in a full\nsurface coverage.",
        "positive": "Depolarizing field and \"real\" hysteresis loops in nanometer-scale\n  ferroelectric films: We give detailed analysis of the effect of depolarizing field in\nnanometer-size ferroelectric capacitors studied by Kim et al. [Phys. Rev. Lett.\n95, 237602 (2005)]. We calculate a critical thickness of the homogeneous state\nand its stability with respect to domain formation for strained thin films of\nBaTiO3 on SrRuO3/SrTiO3 substrate within the Landau theory. While the former\n(2.5nm) is the same as given by ab-initio calculations, the actual critical\nthickness is set by the domains at 1.6nm. There is a large Merz's activation\nfield for polarization relaxation. Remarkably, the results show a_negative_\nslope of the \"actual\" hysteresis loops, a hallmark of the domain structures in\nideal thin films with imperfect screening."
    },
    {
        "anchor": "Magneto-electric coupling in type-I multiferroic ScFeO$_3$: We investigate the electronic structure and the ferroelectric properties of\nthe recently discovered multiferroic ScFeO$_3$ by means of ab-initio\ncalculations. The $3d$ manifold of Fe in the half-filled configuration\nnaturally favors an antiferromagnetic ordering, with a theoretical estimate of\nthe antiferromagnetic N\\'eel temperature in good agreement with the\nexperimental values. We find that the inversion symmetry-breaking is driven by\nthe off-centering of Sc atoms, which results in a large ferroelectric\npolarization of $\\sim$105\\,$\\mu$C/cm$^{2}$. Surprisingly the ferroelectric\npolarization is sensitive to the local magnetization of the Fe atoms resulting\nin a large negative magnetoelectric interaction. This behavior is unexpected in\ntype-I multiferroic materials because the magnetic and ferroelectric orders are\nof different origins.",
        "positive": "Revisiting the storage capacity limit of graphite battery anodes:\n  spontaneous lithium overintercalation at ambient pressure: The market quest for fast-charging, safe, long-lasting and performant\nbatteries drives the exploration of new energy storage materials, but also\npromotes fundamental investigations of materials already widely used.\nPresently, revamped interest in anode materials is observed -- primarily\ngraphite electrodes for lithium-ion batteries. Here, we focus on the upper\nlimit of lithium intercalation in the morphologically quasi-ideal highly\noriented pyrolytic graphite (HOPG), with a LiC$_6$ stoichiometry corresponding\nto 100\\% state of charge (SOC). We prepared a sample by immersion in liquid\nlithium at ambient pressure and investigated it by static $^7$Li nuclear\nmagnetic resonance (NMR). We resolved unexpected signatures of superdense\nintercalation compounds, LiC$_{6-x}$. These have been ruled out for decades,\nsince the highest geometrically accessible composition, LiC$_2$, can only be\nprepared under high pressure. We thus challenge the widespread notion that any\nadditional intercalation beyond LiC$_6$ is not possible under ambient\nconditions. We monitored the sample upon calendaric aging and employed ab\ninitio calculations to rationalise the NMR results. The computed relative\nstabilities of different superdense configurations reveal that non-negligible\noverintercalation does proceed spontaneously beyond the currently accepted\ncapacity limit."
    },
    {
        "anchor": "Nucleation and growth of thin films of rod--like conjugated molecules: Thin films formed from small molecules rapidly gain importance in different\ntechnological fields. To explain their growth, methods developed for\nzero--dimensional atoms as the film forming particles are applied. However, in\norganic thin film growth the dimensionality of the building blocks comes into\nplay. Using the special case of the model molecule para--Sexiphenyl, we will\nemphasize the challenges that arise from the anisotropic and one--dimensional\nnature of building blocks. Differences or common features with other rodlike\nmolecules will be discussed. The typical morphologies encountered for this\ngroup of molecules and the relevant growth modes will be investigated. Special\nattention is given to the transition between flat lying and upright orientation\nof the building blocks during nucleation. We will further discuss methods to\ncontrol the molecular orientation and describe the involved diffusion processes\nqualitatively and quantitatively.",
        "positive": "Order of Epitaxial Self-Assembled Quantum Dots: Linear Analysis: Epitaxial self-assembled quantum dots (SAQDs) are of interest for\nnanostructured optoelectronic and electronic devices such as lasers,\nphotodetectors and nanoscale logic. Spatial order and size order of SAQDs are\nimportant to the development of usable devices. It is likely that these two\ntypes of order are strongly linked; thus, a study of spatial order will also\nhave strong implications for size order. Here a study of spatial order is\nundertaken using a linear analysis of a commonly used model of SAQD formation\nbased on surface diffusion. Analytic formulas for film-height correlation\nfunctions are found that characterize quantum dot spatial order and\ncorresponding correlation lengths that quantify order. Initial atomic-scale\nrandom fluctuations result in relatively small correlation lengths (about two\ndots) when the effect of a wetting potential is negligible; however, the\ncorrelation lengths diverge when SAQDs are allowed to form at a near-critical\nfilm height. The present work reinforces previous findings about anisotropy and\nSAQD order and presents as explicit and transparent mechanism for ordering with\ncorresponding analytic equations. In addition, SAQD formation is by its nature\na stochastic process, and various mathematical aspects regarding statistical\nanalysis of SAQD formation and order are presented."
    },
    {
        "anchor": "Missed surface waves in non-piezoelectric solids: The physical processes taking place at the surface and near the surface of\nsolids is so rich and versatile that sometimes they seem to be the\ninexhaustible subject of fundamental research. In particular, since the\ndiscovery by Lord Rayleigh surface waves in solids focus increased attention of\nscientists, because their experimental and theoretical studies can serve as the\nsource of unique information about the surface impact on the dynamics and\nstructure of the atomic lattice, structural instabilities and phase transitions\ninduced by the surface, and explore the properties of phonons in\nspatially-confined systems The existence of purely shear surface wave is\nimpossible in non-piezoelectrics within the framework of the classical theory\nof elasticity, because the Rayleigh surface waves have different polarization\nand are the mixture of shear and dilatational waves. We showed that the\n\"forbidden\" shear surface wave (shortly Flexo-SW) can propagate near the\nsurface of all crystalline dielectrics due to the omnipresent flexoelectric\ncoupling. The appearance and penetration depth of the Flexo-SW is ruled by the\nflexocoupling strength. In particular the penetration depth of transverse\nacoustic mode diverges in the absence of the flexoelectric coupling and so\nthese waves become indistinguishable from the bulk waves. For paraelectrics\nsuch as strontium titanate with typical flexoeletric coefficients (~2V) the\npenetration depth of the Flexo-SW can reach more than tens microns at THz\nfrequencies. The circumstances can explain the absence of experimental\nobservations of the missed surface waves in thick layers and bulk materials.\nHowever we predict that the peaks of neutron intensity corresponding to the\nsurface Flexo-SW and bulk phonon modes can be separated in non-piezoelectric\nthin films of thickness ~(20 - 50)nm.",
        "positive": "Strain game revisited for complex oxide thin-films: Substrate-film\n  thermal expansion mismatch in PbTiO$_3$: The sensitivity of materials properties, particularly those of perovskite\noxides, to epitaxial strain has been exploited to great advantage to create\nmaterials with new or enhanced properties. Although it has certainly been\nrecognized that mismatch in the thermal expansion coefficients of the bulk and\nsubstrate material will contribute to the misfit strain, the significance of\nthis contribution for ferroelectric perovskite thin-films has not been\nsystematically explored. We use first-principles density functional theory and\nthe example of ferroelectric PbTiO$_3$ thin-films on various substrates to show\nthat ignoring the thermal expansion of the substrate (that is, assuming that\nthe in-plane lattice parameter of the film remains roughly constant as a\nfunction of temperature) results in ferroelectric transition temperatures and\nstructural trends that are completely qualitatively different from calculations\nin which thermal expansion mismatch is properly taken into account. Our work\nsuggests that the concept of a misfit strain defined as a single number is\nparticularly ill-defined for PbTiO$_3$ and invites further study of the\ninterplay between thermal expansion mismatch and structural and functional\nproperties in other thin-film materials."
    },
    {
        "anchor": "Degeneracy removal of spin bands in antiferromagnets with\n  non-interconvertible spin motif pair: Energy bands in antiferromagnets are generally spin degenerate in the absence\nof spin-orbit coupling (SOC). Recent studies [Physical Review B 102, 014422\n(2020)] identified formal symmetry conditions for crystals for which this\ndegeneracy can be lifted even in the zero SOC limit. Such materials could\nenable \"spin-split\" antiferromagnetic spintronics without the burden of use of\nheavy atom compounds. Here, we show that these formal symmetry conditions can\nbe interpreted in terms of easy-to-visualize local motif pair, such as\noctahedra or tetrahedra, each carrying opposite magnetic moments. Collinear\nantiferromagnets with such spin motif pair whose components interconvert by\nneither translation nor spatial inversion will show splitting of spin bands.\nSuch real-space motif-based approach enables an easy way to identify and design\nof materials having spin splitting without the need for spin orbit coupling,\nand offers insights on the magnitude of spin splitting.",
        "positive": "Coherent excitations and electron phonon coupling in Ba/EuFe_2As_2\n  compounds investigated by femtosecond time- and angle-resolved photoemission\n  spectroscopy: We employed femtosecond time- and angle-resolved photoelectron spectroscopy\nto analyze the response of the electronic structure of the 122 Fe-pnictide\nparent compounds Ba/EuFe_2As_2 and optimally doped BaFe_{1.85}Co_{0.15}As_2\nnear the \\Gamma point to femtosecond optical excitation. We identify pronounced\nchanges of the electron population within several 100 meV above and below the\nFermi level, which we explain as combination of (i) coherent lattice\nvibrations, (ii) a hot electron and hole distribution, and (iii) transient\nmodifications of the chemical potential. The response of the three different\nmaterials is very similar. In the Fourier transformation of the time-dependent\nphotoemission intensity we identify three modes at 5.6, 3.3, and 2.6 THz. While\nthe highest frequency mode is safely assigned to the A_{1g} mode, the other two\nmodes require a discussion in comparison to literature. The time-dependent\nevolution of the hot electron distribution follows a simplified description of\na transient three temperature model which considers two heat baths of lattice\nvibrations, which are more weakly and strongly coupled to transiently excited\nelectron population. Still the energy transfer from electrons to the strongly\ncoupled phonons results in a rather weak, momentum-averaged electron-phonon\ncoupling quantified by values for \\lambda<\\omega^2> between 30 and 70 meV^2.\nThe chemical potential is found to present a transient modulation induced by\nthe coherent phonons. This change in the chemical potential is particularly\nstrong in a two band system like in the 122 Fe-pnictide compounds investigated\nhere due to the pronounced variation of the electrons density of states close\nto the equilibrium chemical potential."
    },
    {
        "anchor": "Energetic disorder induced leakage current in organic bulk\n  heterojunction solar cells: comprehending the ultra-high open circuit voltage\n  loss at low temperatures: In organic bulk heterojunction solar cells, the open circuit voltage\n($V_\\mathrm{oc}$) suffers from an ultra-high loss at low temperatures. In this\nwork we investigate the origin of the loss through calculating the\n$V_\\mathrm{oc}-T$ plots with the device model method systematically and\ncomparing it with experimentally observed ones. When the energetic disorder is\nincorporated into the model by considering the disorder-suppressed and\ntemperature-dependent charge carrier mobilities, it is found that for\nnonselective contacts the $V_\\mathrm{oc}$ reduces drastically under the low\ntemperature regime, while for selective contacts the $V_\\mathrm{oc}$ keeps\nincreasing with the decreasing temperature. The main reason is revealed that as\nthe temperature decreases, the reduced mobilities give rise to low charge\nextraction efficiency and small bimolecular recombination rate for the\nphotogenerated charge carriers, so that in the former case they can be\nextracted from the wrong electrode to form a leakage current which counteracts\nthe photocurrent and increases quickly with voltage, leading to the anomalous\nreduction of $V_\\mathrm{oc}$. In addition, it is revealed that the charge\ngeneration rate is slow-varying with temperature and does not induce\nsignificant $V_\\mathrm{oc}$ loss. This work also provides a comprehensive\npicture for the $V_\\mathrm{oc}$ behavior under varying device working\nconditions.",
        "positive": "Kinetics and Intermediate Phases in Epitaxial Growth of Fe3O4 Films from\n  Deposition and Thermal Reduction: We have studied the growth of Fe3O4 (111) epitaxial films on Al2O3 (001)\nsubstrates using a pulsed laser deposition / thermal reduction cycle using an\n{\\alpha}-Fe2O3 target. While direct deposition onto the Al2O3 (001) substrates\nresults in an {\\alpha}-Fe2O3 epilayer, deposition on the Fe3O4 (111) surface\nresults in a {\\gamma}-Fe2O3 epilayer. The kinetics of the transitions between\nFe2O3 and Fe3O4 were studied by measuring the time constants of the\ntransitions. The transition from {\\alpha}-Fe2O3 to Fe3O4 via thermal reduction\nturns out to be very slow, due to the high activation energy. Despite the\nsignificant grain boundaries due to the mismatch between the unit cells of the\nfilm and the substrate, the Fe3O4 (111) films grown from deposition/thermal\nreduction show high crystallinity."
    },
    {
        "anchor": "Comprehensive structural changes in nanoscale-deformed silicon modelled\n  with an integrated atomic potential: In spite of remarkable developments in the field of advanced materials,\nsilicon remains one of the foremost semiconductors of the day. Of enduring\nrelevance to science and technology is silicon's nanomechanical behaviour\nincluding phase transformation, amorphization and dislocations generation,\nparticularly in the context of molecular dynamics and materials research. So\nfar, comprehensive modelling of the whole cycle of events in silicon during\nnanoscale deformation has not been possible, however, due to the limitations\ninherent in the existing interatomic potentials. This paper examines how well\nan unconventional combination of two well-known potentials - the Tersoff and\nStillinger-Weber - can perform in simulating that complexity. Our model\nindicates that an irreversible deformation of silicon (Si-I) is set in motion\nby a transformation to a non-diamond structure (Si-nd), and followed by a\nsubsequent transition to the Si-II and Si-XII' phases\n(Si-I->Si-nd->Si-II->Si-XII'). This leads to the generation of dislocations\nspreading outwards from the incubation zone. In effect, our simulations\nparallel each and every one of the structural changes detected experimentally\nin the deformed material. This includes both the sequence of phase transitions\nand dislocation activity, which - taken together - neither the Tersoff nor\nStillinger-Weber, or indeed any other available Si interatomic potential, is\nable to achieve in its own right. We have sought to additionally validate our\nmethod of merging atomic potentials by applying it to germanium, and found it\ncan equally well predict germanium's transformation from a liquid to amorphous\nstate.",
        "positive": "High-Pressure Monoclinic-Monoclinic Transition in Fergusonite-type\n  HoNbO4: In this paper we perform a high-pressure study of fergusonite-type HoNbO4.\nPowder x-ray diffraction experiments and ab initio density-functional theory\nsimulations provide evidence of a phase transition at 18.9(1.1) GPa from the\nmonoclinic fergusonite-type structure (space group I2/a) to another monoclinic\npolymorph described by space group P21/c. The phase transition is reversible\nand the high-pressure structural behavior is different than the one previously\nobserved in related niobates. The high-pressure phase remains stable up to 29\nGPa. The observed transition involves a change in the Nb coordination number\nfrom 4 to 6, and it is driven by mechanical instabilities. We have determined\nthe pressure dependence of unit-cell parameters of both phases and calculated\ntheir room-temperature equation of state. For the fergusonite-phase we have\nalso obtained the isothermal compressibility tensor. In addition to the\nhigh-pressure studies, we report ambient-pressure Raman and infrared\nspectroscopy measurements. We have been able to identify all the active modes\nof fergusonite-type HoNbO4, which have been assigned based upon\ndensity-functional theory calculations. These simulations also provide the\nelastic constants of the different structures and the pressure dependence of\nthe Raman and infrared modes of the two phases of HoNbO4."
    },
    {
        "anchor": "Exchange Biasing of the Ferromagnetic Semiconductor (Ga,Mn)As by MnO: We provide an overview of progress on the exchange biasing of a ferromagnetic\nsemiconductor (Ga1-xMnxAs) by proximity to an antiferromagnetic oxide layer\n(MnO). We present a detailed characterization study of the antiferromagnetic\nlayer using Rutherford backscattering spectrometry, x-ray photoelectron\nspectroscopy, transmission electron microscopy, and x-ray reflection. In\naddition, we describe the variation of the exchange and coercive fields with\ntemperature and cooling field for multiple samples.",
        "positive": "Visualizing Skin Effects in Conductors with MRI: ${}^7$Li MRI\n  Experiments and Calculations: While experiments on metals have been performed since the early days of NMR\n(and DNP), the use of bulk metal is normally avoided. Instead, often powders\nhave been used in combination with low fields, so that skin depth effects could\nbe neglected. Another complicating factor of acquiring NMR spectra or MRI\nimages of bulk metal is the strong signal dependence on the orientation between\nthe sample and the radio frequency (RF) coil, leading to non-intuitive image\ndistortions and inaccurate quantification. Such factors are particularly\nimportant for NMR and MRI of batteries and other electrochemical devices. Here,\nwe show results from a systematic study combining RF field calculations with\nexperimental MRI of $^7$Li metal to visualize skin depth effects directly and\nto analyze the RF field orientation effect on MRI of bulk metal. It is shown\nthat a certain degree of selectivity can be achieved for particular faces of\nthe metal, simply based on the orientation of the sample. By combining RF field\ncalculations with bulk magnetic susceptibility calculations accurate NMR\nspectra can be obtained from first principles. Such analyses will become\nvaluable in many applications involving battery systems, but also metals, in\ngeneral."
    },
    {
        "anchor": "Valley-Polarized Exciton-Polaritons in a Monolayer Semiconductor: Single layers of transition metal dichalcogenides are two-dimensional direct\nbandgap semiconductors with degenerate, but inequivalent, `valleys' in the\nelectronic structure that can be selectively excited by polarized light.\nCoherent superpositions of light and matter, exciton-polaritons, have been\nobserved when these materials are strongly coupled to photons, but these hybrid\nquasiparticles do not harness the valley-sensitive excitations of monolayer\ntransition metal dichalcogenides. Here, we demonstrate evidence for valley\npolarized exciton-polaritons in monolayers of MoS$_2$ embedded in a dielectric\nmicrocavity. Unlike traditional microcavity exciton-polaritons, these\nlight-matter quasiparticles emit polarized light with spectral Rabi splitting.\nThe interplay of cavity-modified exciton dynamics and intervalley relaxation in\nthe high-cooperativity regime causes valley polarized exciton-polaritons to\npersist to room temperature, distinct from the vanishing polarization in bare\nmonolayers. Achieving polarization-sensitive polaritonic devices operating at\nroom temperature presents a pathway for manipulating novel valley degrees of\nfreedom in coherent states of light and matter.",
        "positive": "Structural Stability and Defect Energetics of ZnO from Diffusion Quantum\n  Monte Carlo: We have applied the many-body ab-initio diffusion quantum Monte Carlo (DMC)\nmethod to study Zn and ZnO crystals under pressure, and the energetics of the\noxygen vacancy, zinc interstitial and hydrogen impurities in ZnO. We show that\nDMC is an accurate and practical method that can be used to characterize\nmultiple properties of materials that are challenging for density functional\ntheory approximations. DMC agrees with experimental measurements to within 0.3\neV, including the band-gap of ZnO, the ionization potential of O and Zn, and\nthe atomization energy of O$_2$, ZnO dimer, and wurtzite ZnO. DMC predicts the\noxygen vacancy as a deep donor with a formation energy of 5.0(2) eV under\nO-rich conditions and thermodynamic transition levels located between 1.8 and\n2.5 eV from the valence band maximum. Our DMC results indicate that the\nconcentration of zinc interstitial and hydrogen impurities in ZnO should be low\nunder n-type, and Zn- and H-rich conditions because these defects have\nformation energies above 1.4 eV under these conditions. Comparison of DMC and\nhybrid functionals shows that these DFT approximations can be parameterized to\nyield a general correct qualitative description of ZnO. However, the formation\nenergy of defects in ZnO evaluated with DMC and hybrid functionals can differ\nby more than 0.5 eV."
    },
    {
        "anchor": "A new class of topological insulators from I-III-IV half-Heusler\n  compounds with strong band inversion strength: In this paper, by first principle calculations, we investigate systematically\nthe band topology of a new half-Heusler family with composition of\nI(A)-III(A)-IV(A). The results clearly show that many of the I-III-IV\nhalf-Heusler compounds are in fact promising to be topological insulator\ncandidates. The characteristic feature of these new topological insulators is\nthe naturally strong band inversion strength (up to -2eV) without containing\nheavy elements. Moreover, we found that both the band inversion strength and\nthe topological insulating gap can be tailored through strain engineering, and\ntherefore would be grown epitaxially in the form of films, and useful in\nspintronics and other applications.",
        "positive": "Voltage Control of Perpendicular Exchange Bias in Multiferroic\n  Heterostructures: Perpendicular exchange bias (EB), which combines the perpendicular magnetic\nanisotropy and the ferromagnetic (FM) - antiferromagnetic (AFM) exchange\ncoupling, is extremely important in the high-density AFM spintronics. However,\nthe effective modulation of EB remains challenging, since the alternant spins\nat the AFM/FM interface are strongly pinned by the AFM layer. Voltage tuning of\nEB through the magnetoelectric coupling provides a potential way to achieve a\nrapid magnetization switching in an energy-efficient manner. Nevertheless, the\ninterfacial strain mediation of perpendicular EB induced by E-field remains\nunexplored. In this work, we obtain perpendicular EB nanostructure by\nroom-temperature fabrication process, and demonstrate the voltage tunable\nperpendicular EB in Pt/IrMn/(Co/Pt)2/Ta/(011) Pb(Mg1/3Nb2/3)O3-PbTiO3\nmultiferroic heterostructure. To enhance the voltage control effect on\nperpendicular EB, we further investigate both strain-mediated magnetoelectric\ncoupling and ionic liquid gating method in the thinned EB system with the\nstructure of Pt/IrMn/Co/Pt/Ta. As a result, the voltage induced lattice\ndistortion effectively transmits to the AFM/FM interface, while the charge\naccumulation in gating method generates a relatively large hysteresis loop\noffset that has not been observed before at room temperature. The voltage\nmanipulation of perpendicular EB at room temperature provides new possibilities\ntowards novel AFM devices and memories with great energy-efficiency and\nultra-high density."
    },
    {
        "anchor": "A three-dimensional domain decomposition method for large-scale DFT\n  electronic structure calculations: With tens of petaflops supercomputers already in operation and exaflops\nmachines expected to appear within the next 10 years, efficient parallel\ncomputational methods are required to take advantage of such extreme-scale\nmachines. In this paper, we present a three-dimensional domain decomposition\nscheme for enabling large-scale electronic calculations based on density\nfunctional theory (DFT) on massively parallel computers. It is composed of two\nmethods: (i) atom decomposition method and (ii) grid decomposition method. In\nthe former, we develop a modified recursive bisection method based on inertia\ntensor moment to reorder the atoms along a principal axis so that atoms that\nare close in real space are also close on the axis to ensure data locality. The\natoms are then divided into sub-domains depending on their projections onto the\nprincipal axis in a balanced way among the processes. In the latter, we define\nfour data structures for the partitioning of grids that are carefully\nconstructed to make data locality consistent with that of the clustered atoms\nfor minimizing data communications between the processes. We also propose a\ndecomposition method for solving the Poisson equation using three-dimensional\nFFT in Hartree potential calculation, which is shown to be better than a\npreviously proposed parallelization method based on a two-dimensional\ndecomposition in terms of communication efficiency. For evaluation, we perform\nbenchmark calculations with our open-source DFT code, OpenMX, paying particular\nattention to the O(N) Krylov subspace method. The results show that our scheme\nexhibits good strong and weak scaling properties, with the parallel efficiency\nat 131,072 cores being 67.7% compared to the baseline of 16,384 cores with\n131,072 diamond atoms on the K computer.",
        "positive": "Magnetic Properties of a Quantum Ferrimagnet: NiCu(pba)(D_2O)_3 . 2D_2O: We report the results of magnetic measurements on a powder sample of\nNiCu(pba)(D_2O)_3 \\cdot 2D_2O$ (pba=1,3-propylenebis(oxamato)) which is one of\nthe prototypical examples of an $S$=1/2 and 1 ferrimagnetic chain.\nSusceptibility($\\chi$) shows a monotonous increase with decreasing temperature\n(T) and reaches a maximum at about 7 K. In the plot of $\\chi T$ versus $T$, the\nexperimental data exhibit a broad minimum and are fit to the $\\chi T$ curve\ncalculated for the ferrimagnetic Heisenberg chain composed of S=1/2 and 1. From\nthis fit, we have evaluated the nearest-neighbor exchange constant $J/k_B=121\nK$, the g-values of Ni$^{2+}$ and Cu$^{2+}$, $g_{Ni}$=2.22 and $g_{Cu}$=2.09,\nrespectively. Applied external field dependence of $\\chi T$ at low temperatures\nis reproduced fairly well by the calculation for the same ferrimagnetic model."
    },
    {
        "anchor": "Mechanistic Insights into Temperature Effects for Ionic Conductivity in\n  Li6PS5Cl: Ensuring solid-state lithium batteries perform well across a wide temperature\nrange is crucial for their practical use. Molecular dynamics (MD) simulations\ncan provide valuable insights into the temperature dependence of the battery\nmaterials, however, the high computational cost of ab initio MD poses\nchallenges for simulating ion migration dynamics at low temperatures. To\naddress this issue, accurate machine-learning interatomic potentials were\ntrained, which enable efficient and reliable simulations of the ionic diffusion\nprocesses in Li6PS5Cl over a large temperature range for long-time evolution.\nOur study revealed the significant impact of subtle lattice parameter\nvariations on Li+ diffusion at low temperatures and identified the increasing\ninfluence of surface contributions as the temperature decreases. Our findings\nelucidate the factors influencing low temperature performance and present\nstrategic guidance towards improving the performance of solid-state lithium\nbatteries under these conditions.",
        "positive": "Phonon-assisted Auger enables ultrafast charge transfer in CdSe Quantum\n  Dot/Organic Molecule: Charge transfer between photoexcited quantum dots and molecular acceptors is\none of the key limiting processes in most applications of colloidal\nnanostructures, most prominently in photovoltaics. An atomistic detailed\ndescription of this process would open new ways to optimize existing and create\nnew structures with targeted properties. We achieve a one-to-one comparison\nbetween ab-initio non-adiabatic molecular dynamics calculations and transient\nabsorption spectroscopy experiments, which allows us to draw a comprehensive\natomistic picture of the charge transfer process, following the time evolution\nof the charge carrier across the electronic landscape and identifying the\nthereby induced vibrations. For two quantum dot sizes we find two qualitatively\ndifferent processes. For the larger structure we find a relatively slow (\\tau =\n516 fs) transfer process that we explain by the existence of a large energy\ndetuning and weak vibronic coupling. For the smaller structure the process is\nultrafast (\\tau = 20 fs) due to an efficient, phonon-assisted Auger process\ntriggered by a strong electron-hole coupling."
    },
    {
        "anchor": "Optical properties of metallic (III,Mn)V ferromagnetic semiconductors in\n  the infrared to visible range: We report on a study of the ac conductivity and magneto-optical properties of\nmetallic ferromagnetic (III,Mn)V semiconductors in the infrared to visible\nspectrum. Our analysis is based on the successful kinetic exchange model for\n(III,Mn)V ferromagnetic semiconductors. We perform the calculations within the\nKubo formalism and treat the disorder effects pertubatively within the Born\napproximation, valid for the metallic regime. We consider an eight-band\nKohn-Luttinger model (six valence bands plus two conduction bands) as well as a\nten-band model with additional dispersionless bands simulating\nphenomenologically the upper-mid-gap states induced by antisite and\ninterstitial impurities. These models qualitatively account for\noptical-absorption experiments and predict new features in the mid-infrared\nKerr angle and magnetic-circular-dichroism properties as a function of Mn\nconcentration and free carrier density.",
        "positive": "Buckyball sandwiches: Two-dimensional (2D) materials have considerably expanded the field of\nmaterials science in the last decade. Even more recently, various 2D materials\nhave been assembled into vertical van der Waals heterostacks, and it has been\nproposed to combine them with other low- dimensional structures to create new\nmaterials with hybridized properties. Here, we demonstrate the first direct\nimages of a suspended 0D/2D heterostructure incorporating $C_{60}$ molecules\nbetween two graphene layers in a buckyball sandwich structure. We find clean\nand ordered $C_{60}$ islands with thicknesses down to one molecule, shielded by\nthe graphene layers from the microscope vacuum and partially protected from\nradiation damage during scanning transmission electron microscopy imaging. The\nsandwich structure serves as a 2D nanoscale reaction chamber allowing the\nanalysis of the structure of the molecules and their dynamics at atomic\nresolution."
    },
    {
        "anchor": "Detection of Single Electron Charging in an Individual InAs Quantum Dot\n  by Noncontact Atomic Force Microscopy: Single electron charging in an individual InAs quantum dot was observed by\nelectrostatic force measurements with an atomic force microscope (AFM). The\nresonant frequency shift and the dissipated energy of an oscillating AFM\ncantilever were measured as a function of the tip-back electrode voltage and\nthe resulting spectra show distinct jumps when the tip was positioned above the\ndot. The observed jumps in the frequency shift, with corresponding peaks in\ndissipation, are attributed to a single electron tunneling between the dot and\nthe back electrode governed by Coulomb blockade effect, and are consistent with\na model based on the free energy of the system. The observed phenomenon may be\nregarded as the ``force version'' of the Coulomb blockade effect.",
        "positive": "Ultrafast switching dynamics of the ferroelectric order in\n  stacking-engineered ferroelectrics: The recently discovered ferroelectricity of van der Waals bilayers offers an\nunconventional route to improve the performance of devices. Key parameters such\nas switching field and speed depend on the static and dynamic properties of\ndomain walls (DWs). Here we theoretically explore the properties of textures in\nstacking-engineered ferroelectrics from first principles. Employing a\nmachine-learning potential model, we present results of large-scale atomistic\nsimulations of stacking DWs and Moir\\'e structure of boron nitride bilayers. We\npredict that the competition between the switching barrier of stable\nferroelectric states and the in-plane lattice distortion leads to a DW width of\nthe order of ten nanometers. DWs motion reduces the critical ferroelectric\nswitching field of a monodomain by two orders of magnitude, while high\ndomain-wall velocities allow domain switching on a picosecond-timescale. The\nsuperior performance compared to conventional ferroelectrics (or ferromagnets)\nmay enable ultrafast and power-saving non-volatile memories. By twisting the\nbilayer into a stacking Moir\\'e structure, the ferroelectric transforms into a\nsuper-paraelectric since DWs move under ultralow electric fields."
    },
    {
        "anchor": "Antiferromagnetic interactions in single crystalline Zn1-xCoxO thin\n  films: In a rather contradictory situation regarding magnetic data on Co-doped ZnO,\nwe have succeeded in fabricating high-quality single crystalline Zn1-xCoxO\n(x=0.003-0.07) thin films. This gives us the possibility, for the first time,\nto examine the it intrinsic magnetic properties of ZnO:Co at a quantitative\nlevel and therefore to address several unsolved problems, the major one being\nthe nature of the Co-Co interaction in the ZnO structure.",
        "positive": "Influence of high pressure on the remarkable itinerant electron\n  behaviour in Y$_{0.7}$Er$_{0.3}$Fe$_2$D$_{4.2}$ compounds: Monoclinic Y$_{0.7}$Er$_{0.3}$Fe$_2$D$_{4.2}$ compound exhibits unusual\nmagnetic properties with different field induced magnetic transitions. The\ndeuteride is ferrimagnetic at low temperature and the Er and Fe sublattices\npresent magnetic transitions at different temperatures. The Er moments are\nordered below T$_{Er}$=55 K, whereas the Fe moments remain ferromagnetically\ncoupled up to T$_{M0}$ = 66 K. At T$_{M0}$ the Fe moments display a sharp\nferromagnetic-antiferromagnetic transition (FM-AFM) through an itinerant\nelectron metamagnetic (IEM) behaviour very sensitive to any volume change.\nY$_{0.7}$Er$_{0.3}$Fe$_2$D$_{4.2}$ becomes paramagnetic above T$_N$=125 K. The\npressure dependence of T$_{Er}$ and T$_{M0}$ have been extracted from magnetic\nmeasurements under hydrostatic pressure up to 0.49 GPa. Both temperatures\ndecrease linearly upon applied pressure with dT$_{Er}$/dP=-126 and dTM0/dP=-140\nK.GPa$^{-1}$ for a field of B=0.03 T. Both magnetic Er and ferromagnetic Fe\norder disappear at P=0.44(4) GPa. However, under a larger applied field B=5 T,\ndT$_{M0}$/dP=-156 K.GPa$^{-1}$ whereas dT$_{Er}$/dP=-134 K.GPa$^{-1}$ showing a\nweaker sensitivity to pressure and magnetic field. At 2 K the decrease of the\nsaturation magnetization under pressure can be attributed to a reduction of the\nmean Er moment due to canting and/or crystal field effect. Above T$_{M0}$ the\nmagnetization curves display a metamagnetic behaviour from AFM to FM state,\nwhich is also very sensitive to the applied pressure. The transition field\nB$_{trans}$, which increases linearly upon heating, is shifted to lower\ntemperature upon applied pressure with dT=-17 K between 0 and 0.11 GPa. These\nresults show a strong decoupling of the Er and Fe magnetic sublattices versus\ntemperature, applied field and pressure."
    },
    {
        "anchor": "Universal and Efficient p-Doping of Organic Semiconductors by\n  Electrophilic Attack of Cations: Doping is of great importance to tailor the electrical properties of\nsemiconductors. However, the present doping methodologies for organic\nsemiconductors (OSCs) are either inefficient or can only apply to a small\nnumber of OSCs, seriously limiting their general application. Herein, we reveal\na novel p-doping mechanism by investigating the interactions between the dopant\ntrityl cation and poly(3-hexylthiophene) (P3HT). It is found that electrophilic\nattack of the trityl cations on thiophenes results in the formation of\nalkylated ions that induce electron transfer from neighboring P3HT chains,\nresulting in p-doping. This unique p-doping mechanism can be employed to dope\nvarious OSCs including those with high ionization energy (IE=5.8 eV). Moreover,\nthis doping mechanism endows trityl cation with strong doping ability, leading\nto polaron yielding efficiency of 100 % and doping efficiency of over 80 % in\nP3HT. The discovery and elucidation of this novel doping mechanism not only\npoints out that strong electrophiles are a class of efficient p-dopants for\nOSCs, but also provides new opportunities towards highly efficient doping of\nOSCs.",
        "positive": "New Misfit-Layered Cobalt Oxide (CaOH)1.14CoO2: We found a new cobalt oxide (CaOH)1.14CoO2 by utilizing the high-pressure\ntechnique. X-ray and electron diffraction studies revealed that the compound\nhas layer structure which consists of CdI2-type CoO2 layers and rock-salt-type\ndouble CaOH atomic layers. The two subcells have incommensurate periodicity\nalong the a-axis, resulting in modulated crystal structure due to the\ninter-subcell interaction. The structural modulation affects carrier conduction\nthrough the potential randomness. We found that the two-dimensional (2-D)\nvariable-range hopping (VRH) regime with hole conduction is dominant at low\ntemperature for this compound, and that the conduction mechanism undergoes\ncrossover from the 2-D VRH regime to thermal activation-energy type one with\nincreasing temperature. Based on the experimental results of resistivity,\nthermoelectric power, magnetic susceptibility and specific heat measurements,\nwe suggested a possible electronic-band structure model to explain these\nresults. The cobalt t2g-derivative band crosses Fermi energy level near the\nband edge, yielding small finite density of localized states at the Fermi level\nin the band. The observed resistivity, Seebeck coefficient, large Pauli\nparamagnetic component in the magnetic susceptibility and comparatively small\nSommerfeld constant in the specific heat are principally attributed to the\nholes in the t2g-derivative band. We estimated the Wilson ratio to be about\n2.8, suggesting the strong electron correlation realized in this compound."
    },
    {
        "anchor": "The Breakdown of Linear Elastic Fracture Mechanics near the Tip of a\n  Rapid Crack: We present high resolution measurements of the displacement and strain fields\nnear the tip of a dynamic (Mode I) crack. The experiments are performed on\npolyacrylamide gels, brittle elastomers whose fracture dynamics mirror those of\ntypical brittle amorphous materials. Over a wide range of propagation\nvelocities ($0.2-0.8c_s$), we compare linear elastic fracture mechanics (LEFM)\nto the measured near-tip fields. We find that, sufficiently near the tip, the\nmeasured stress intensity factor appears to be non-unique, the crack tip\nsignificantly deviates from its predicted parabolic form, and the strains ahead\nof the tip are more singular than the $r^{-1/2}$ divergence predicted by LEFM.\nThese results show how LEFM breaks down as the crack tip is approached.",
        "positive": "Space-time symmetry violation of the fields in quasi-2D ferrite\n  particles with magnetic-dipolar-mode oscillations: In magnetic systems with reduced dimensionality, the effects of dipolar\ninteractions allow the existence of long-range ordered phases. Long-range\nmagnetic-dipolar interactions are at the heart of the explanation of many\npeculiar phenomena observed in nuclear magnetic resonance, ferromagnetic\nresonance, and Bose-Einstein-condensate structures. In this paper we show that\nmagnetic-dipolar-modes (MDMs) in quasi-2D ferrite disks are characterized by\nsymmetry breaking effects. Our analysis is based on postulates about a physical\nmeaning of the magnetostatic-potential function as a complex scalar wave\nfunction, which presumes the long-range phase correlations. An important\nfeature of the MDM oscillations in a ferrite disk concerns the fact that a\nstructure with symmetric parameters and symmetric basic equations goes into\neigenstates that are not space-time symmetric. The proper solutions are found\nbased on an analysis of magnetostatic-wave propagation in a helical coordinate\nsystem. For a ferrite disk, we show that while a composition of two helical\nwaves may acquire a geometrical phase over-running of during a period, every\nseparate helical wave has a dynamical phase over-running of and so behaves as a\ndouble-valued function. We demonstrate that unique topological structures of\nthe fields in a ferrite disk are intimately related to the symmetry breaking\nproperties of MDM oscillations. The solutions give the MDM power-flow-density\nvortices with cores at the disk center and azimuthally running waves of\nmagnetization. One can expect that the proposed models of long-range ordered\nphases and space-time violation properties of magnetic-dipolar interactions can\nbe used in other magnetic structures, different from the\nferromagnetic-resonance system with reduced dimensionality."
    },
    {
        "anchor": "Polymerisation Degree and Raman Identification of Ancient Glasses used\n  for Jewellery, Ceramics Enamels and Mosaics: We demonstrate the utility of Raman spectroscopy as a technique for the\nidentification of ancient glasses and enamel coatings of ceramics. As for any\nsilicate glasses, the addition of network modifiers breaks the Si-O linkages\nand modifies the degree of polymerisation and hence the relative intensity of\nthe Si-O bending and stretching modes. We demonstrate empirically that the\nratio of these envelopes is well correlated to the glass structure and to the\nused firing technology. Spectral Qn components assigned to isolated and\nconnected SiO4 vibrational units allow more precise analysis. Selected\nporcelains, faiences, potteries and glasses representative of the different\nAsian, Islamic and European production technologies were studied. Modern\nporcelain enamels are used as compositional references.",
        "positive": "Reversible Control of Magnetic Interactions by Electric Field in a\n  Single Phase Material: Intrinsic magnetoelectric coupling describes the interaction between magnetic\nand electric polarization through an inherent microscopic mechanism in a single\nphase material. This phenomenon has the potential to control the magnetic state\nof a material with an electric field, an enticing prospect for device\nengineering. We demonstrate 'giant' magnetoelectric cross-field control in a\nsingle phase rare earth titanate film. In bulk form, EuTiO3 is\nantiferromagnetic. However, both anti and ferromagnetic interactions coexist\nbetween different nearest neighbor europium ions. In thin epitaxial films,\nstrain can be used to alter the relative strength of the magnetic exchange\nconstants. Here, we not only show that moderate biaxial compression\nprecipitates local magnetic competition, but also demonstrate that the\napplication of an electric field at this strain state, switches the magnetic\nground state. Using first principles density functional theory, we resolve the\nunderlying microscopic mechanism resulting in the EuTiO3 G-type magnetic\nstructure and illustrate how it is responsible for the 'giant' cross-field\nmagnetoelectric effect."
    },
    {
        "anchor": "ab initio Electronic Transport Model with Explicit Solution to the\n  Linearized Boltzmann Transport Equation: Accurate models of carrier transport are essential for describing the\nelectronic properties of semiconductor materials. To the best of our knowledge,\nthe current models following the framework of the Boltzmann transport equation\n(BTE) either rely heavily on experimental data (i.e., semi-empirical), or\nutilize simplifying assumptions, such as the constant relaxation time\napproximation (BTE-cRTA). While these models offer valuable physical insights\nand accurate calculations of transport properties in some cases, they often\nlack sufficient accuracy -- particularly in capturing the correct trends with\ntemperature and carrier concentration. We present here a general transport\nmodel for calculating low-field electrical drift mobility and Seebeck\ncoefficient of n-type semiconductors, by explicitly considering all relevant\nphysical phenomena (i.e. elastic and inelastic scattering mechanisms). We first\nrewrite expressions for the rates of elastic scattering mechanisms, in terms of\nab initio properties, such as the band structure, density of states, and polar\noptical phonon frequency. We then solve the linear BTE to obtain the\nperturbation to the electron distribution -- resulting from the dominant\nscattering mechanisms -- and use this to calculate the overall mobility and\nSeebeck coefficient. Using our model, we accurately calculate electrical\ntransport properties of the compound n-type semiconductors, GaAs and InN, over\nvarious ranges of temperature and carrier concentration. Our fully predictive\nmodel provides high accuracy when compared to experimental measurements on both\nGaAs and InN, and vastly outperforms both semi-empirical models and the\nBTE-cRTA. Therefore, we assert that this approach represents a first step\ntowards a fully ab initio carrier transport model that is valid in all compound\nsemiconductors.",
        "positive": "Optimum control of broadband noise by barriers based on sonic crystals: It is demonstrated that sonic crystals (periodic structures of sound\nscatterers) can be used to design acoustic barriers that attenuate efficiently\nbroadband noise. Traffic noise is chosen here as an example in which our design\nprocedure is applied. The structures consist of cylindrical units containing\nrubber crumb, a sound absorbing material. An optimization algorithm is\ndeveloped to obtain the material distribution and the dimensions of the sonic\ncrystal giving the best attenuation properties for this noise. The good\nagreement found between predictions and measurements for a barrier (3m height)\ncharacterized in a transmission room gives strong support to our proposal."
    },
    {
        "anchor": "Electronic and optical excitations at the\n  pyridine/ZnO(10$\\overline{1}$0) hybrid interface: By combining all-electron density-functional theory with many-body\nperturbation theory, we investigate a prototypical inorganic/organic hybrid\nsystem, composed of pyridine molecules that are chemisorbed on the non-polar\nZnO($10\\overline{1}0$) surface. We employ the $G_0W_0$ approximation to\ndescribe its one-particle excitations in terms of the quasi-particle band\nstructure, and solve the Bethe-Salpeter equation for obtaining the absorption\nspectrum. The different character of the constituents leads to very diverse\nself-energy corrections of individual Kohn-Sham states, and thus the $G_0W_0$\nband structure is distinctively different from its DFT counterpart, i.e.,\nmany-body effects cannot be regarded as a rigid shift of the conduction bands.\nWe explore the nature of the optical excitations at the interface over a wide\nenergy range and show that various kinds of electron-hole pairs are formed,\ncomprising hybrid excitons and (hybrid) charge-transfer excitations. The\nabsorption onset is characterized by a strongly bound bright ZnO-dominated\nhybrid exciton. For selected examples of either exciton type, we analyze the\nindividual contributions from the valence and conduction bands and discuss the\nbinding strength and extension of the electron-hole wavefunctions.",
        "positive": "Kinetics and thermodynamics of carbon segregation and graphene growth on\n  Ru(0001): We measure the concentration of carbon adatoms on the Ru(0001) surface that\nare in equilibrium with C atoms in the crystal's bulk by monitoring the\nelectron reflectivity of the surface while imaging. During cooling from high\ntemperature, C atoms segregate to the Ru surface, causing graphene islands to\nnucleate. Using low-energy electron microscopy (LEEM), we measure the growth\nrate of individual graphene islands and, simultaneously, the local\nconcentration of C adatoms on the surface. We find that graphene growth is fed\nby the supersaturated, two-dimensional gas of C adatoms rather than by direct\nexchange between the bulk C and the graphene. At long times, the rate at which\nC diffuses from the bulk to the surface controls the graphene growth rate. The\ncompetition among C in three states - dissolved in Ru, as an adatom, and in\ngraphene - is quantified and discussed. The adatom segregation enthalpy\ndetermined by applying the simple Langmuir-McLean model to the\ntemperature-dependent equilibrium concentration seriously disagrees with the\nvalue calculated from first-principles. This discrepancy suggests that the\nassumption in the model of non-interacting C is not valid."
    },
    {
        "anchor": "Going Beyond the Cumulant Approximation II:Power Series Correction to\n  Single Particle Green's Function in 1D Holstein Chain: Previously, we introduced a method for systematically correcting a\nquasiparticle green's function via a power series expansion. Here we present an\nODE based formalisms of power series correction that goes beyond the cumulant\napproximation and implement it to 1D Holstein chain for a wide range of\ncoupling strengths in a scalable and inexpensive fashion at both zero and\nfinite temperature. We show that this first differential formalism of the power\nseries is both qualitatively and quantitatively in excellent agreement with\nexact diagonalization results on 1D Holstein chain with dispersive bosons for a\nlarge range of electron-boson coupling strength. We investigate carrier mass\ngrowth rate and carrier energy displacement across a wide range of coupling\nstrength. Finally, we present a heuristic argument which predicts most of the\nrich satellite structure without explicit calculation.",
        "positive": "Experimental Study of the Intrinsic and Extrinsic Transport Properties\n  of Graphite and Multigraphene Samples: This work deals with the intrinsic and extrinsic properties of the graphene\nlayers inside the graphite structure, in particular the influence of defects\nand interfaces. We discuss the evidence for ballistic transport found in\nmesoscopic graphite samples and the possibility to obtain the intrinsic carrier\ndensity of graphite, without the need of free parameters or arbitrary\nassumptions. The influence of internal interfaces on the transport properties\nof bulk graphite is described in detail. We show that in specially prepared\nmultigraphene samples the transport properties show clear signs for the\nexistence of granular superconductivity within the graphite interfaces. We\nargue that the superconducting-insulator or metal-insulator transition (MIT)\nreported in the literature for bulk graphite is not intrinsic of the graphite\nstructure but it is due to the influence of these interfaces. Current-Voltage\ncharacteristics curves reveal Josephson-like behavior at the interfaces with\nsuperconducting critical temperatures above 150K."
    },
    {
        "anchor": "A general method for multiresolutional analysis of mesoscale features in\n  dark-field x-ray microscopy images: Dark-field x-ray microscopy utilizes Bragg diffraction to collect full-field\nx-ray images of \"mesoscale\" structure of ordered materials. Information\nregarding the structural heterogeneities and their physical implications is\ngleaned through the quantitative analyses of these images. Namely, one must be\nable to extract diffraction features that arise from lattice modulations or\ninhomogeneities, quantify said features, and identify and track patterns in the\nrelevant quantitative properties in subsequent images. Due to the necessity to\ntrack features with a wide array of shapes and length scales while maintaining\nspatial resolution, wavelet transforms were chosen as a potent signal analysis\ntool. In addition to addressing multiple length scales, this method can be used\nin conjunction with other signal processing methods such as image binarization\nfor increased functionality. In this article, we demonstrate three effective\nuse of wavelet analyses pertaining to DFXM. We show how to extract and track\nsmooth linear features-which are diffraction manifestations of twin\nboundaries-as the sample orientation changes as it is rotated about momentum\ntransfer. Secondly, we show that even the simplest wavelet transform, the Haar\ntransform, can be used to capture the primary features in DFXM images, over a\nrange of length scales in different regions of interest within a single image\nenabling localized reconstruction. As a final application, we extend these\ntechniques to determine when a DFXM image is in focus.",
        "positive": "Nanoscale Voltage Enhancement at Cathode Interfaces in Li-ion Batteries: Interfaces are ubiquitous in Li-ion battery electrodes, occurring across\ncompositional gradients, regions of multiphase intergrowths, and between\nelectrodes and solid electrolyte interphases or protective coatings. However,\nthe impact of these interfaces on Li energetics remains largely unknown. In\nthis work, we calculated Li intercalation-site energetics across cathode\ninterfaces and demonstrated the physics governing these energetics on both\nsides of the interface. We studied the olivine/olivine-structured\nLixFePO4/LixMPO4 (x=0 and 1, M=Co, Ti, Mn) and layered/layered-structured\nLiNiO2/TiO2 interfaces to explore different material structures and transition\nmetal elements. We found that across an interface from a high- to low-voltage\nmaterial the Li voltage remains constant in the high-voltage material and\ndecays approximately linearly in the low-voltage region, approaching the Li\nvoltage of the low-voltage material. This effect ranges from 0.5-9nm depending\non the interfacial dipole screening. This effect provides a mechanism for a\nhigh-voltage material at an interface to significantly enhance the Li\nintercalation voltage in a low-voltage material over nanometer scale. We showed\nthat this voltage enhancement is governed by a combination of electron transfer\n(from low- to high-voltage regions), strain and interfacial dipole screening.\nWe explored the implications of this voltage enhancement for a novel\nheterostructured-cathode design and redox pseudocapacitors."
    },
    {
        "anchor": "Electron-Phonon Interactions in Graphene, Bilayer Graphene, and Graphite: Using first-principles techniques, we calculate the renormalization of the\nelectron Fermi velocity and the vibrational lifetimes arising from\nelectron-phonon interactions in doped bilayer graphene and in graphite and\ncompare the results with the corresponding quantities in graphene. For similar\nlevels of doping, the Fermi velocity renormalization in bilayer graphene and in\ngraphite is found to be approximately 30% larger than that in graphene. In the\ncase of bilayer graphene, this difference is shown to arise from the interlayer\ninteraction. We discuss our findings in the light of recent photoemission and\nRaman spectroscopy experiments.",
        "positive": "Influence of Functionalized Fullerene Structure on Polymer Photovoltaic\n  Degradation: The time dependence of device performance has been measured for photocells\nusing blends containing the conjugated polymer,\npoly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) with two\ndifferent functionalized C60 electron acceptor molecules: commercially\navailable [6,6]-phenyl C61 butyric acid methyl ester (PCBM) or [6,6]-phenyl C61\nbutyric acid octadecyl ester (PCBOD) produced in this laboratory. Performance\nwas characterized by the short-circuit current output of the devices, with the\ntime dependence of PCBM samples typically degrading exponentially. Variations\nin the characteristic lifetime of the devices were observed to depend on the\nmolar fraction of the electron acceptor molecules (calculated with respect to\nthe MEH-PPV monomer fraction). In comparison to the PCBM samples, the stability\nof the PCBOD blends was significantly enhanced, with a one or two order of\nmagnitude improvement. Corresponding spectroscopic data with similar time\nevolution as the transport measurements suggests an independent means for\ndetermining and understanding degradation mechanisms."
    },
    {
        "anchor": "In-plane to perpendicular magnetic anisotropy switching in\n  heavily-Fe-doped ferromagnetic semiconductor (Ga,Fe)Sb with high Curie\n  temperature: We report switching of magnetic anisotropy (MA) from in-plane to\nperpendicular with increasing the thickness d of a (001)-oriented\nferromagnetic-semiconductor (FMS) (Ga0.7,Fe0.3)Sb layer with a high Curie\ntemperature (Tc > 320 K), using ferromagnetic resonance at room temperature. We\nshow that the total MA energy (E) along the [001] direction changes its sign\nfrom positive (in-plane) to negative (perpendicular) with increasing d above an\neffective critical value \\mathrm{d}_\\mathrm{C}^\\mathrm{*}\\ ~ 42 nm. We reveal\nthat (Ga,Fe)Sb has two-fold symmetry in the film plane. Meanwhile, in the plane\nperpendicular to the film including the in-plane [110] axis, the two-fold\nsymmetry with the easy magnetization axis along [110] changes to four-fold\nsymmetry with easy magnetization axis along <001> with increasing d. This\npeculiar behavior is different from that of (Ga,Mn)As, in which only the\nin-plane MA depends on the film thickness and has four-fold symmetry due to its\ndominant cubic anisotropy along the <100> axes. This work provides an important\nguide for controlling the easy magnetization axis of high-Tc FMS (Ga,Fe)Sb for\nroom-temperature device applications.",
        "positive": "Controlling crystal symmetries in phase-field crystal models: We investigate the possibility to control the symmetry of ordered states in\nphase-field crystal models by tuning nonlinear resonances. In two dimensions,\nwe find that a state of square symmetry as well as coexistence between squares\nand hexagons can be easily obtained. In contrast, it is delicate to obtain\ncoexistence of squares and liquid. We develop a general method for constructing\nfree energy functionals that exhibit solid-liquid coexistence with desired\ncrystal symmetries. As an example, we develop a free energy functional for\nsquare-liquid coexistence in two dimensions. A systematic analysis for\ndetermining the parameters of the necessary nonlinear terms is provided. The\nimplications of our findings for simulations of materials with simple cubic\nsymmetry are discussed."
    },
    {
        "anchor": "Magnetic properties of Co/Ni-based multilayers with Pd and Pt insertion\n  layers: In this study, the influence of Pd and Pt insertion layers in Co/Ni\nmultilayers (MLs) on their magnetic properties, e.g. magnetic anisotropies,\nsaturation magnetization, coercivity, magnetic domain size, and Curie\ntemperature, is investigated. We compare three series of [Co/Ni/X]N ML systems\n(X = Pd, Pt, no insertion layer), varying the individual Co layer thickness as\nwell as the repetition number N. All three systems behave very similarly for\nthe different Co layer thicknesses. For all systems, a maximum effective\nmagnetic anisotropy was achieved for MLs with a Co layer thickness between 0.15\nnm and 0.25 nm. The transition from an out-of-plane to an in-plane system\noccurs at about 0.4 nm of Co. While [Co(0.2 nm)/Ni(0.4 nm)]N MLs change their\npreferred easy magnetization axis from out-of-plane to in-plane after 6 bilayer\nrepetitions, insertion of Pd and Pt results in an extension of this transition\nbeyond 15 repetitions. The maximum effective magnetic anisotropy was more than\ndoubled from 105 kJ/m3 for [Co/Ni]3 to 275 and 186 kJ/m3 for Pt and Pd,\nrespectively. Furthermore, the insertion layers strongly reduce the initial\nsaturation magnetization of 1100 kA/m of Co/Ni MLs and lower the Curie\ntemperature from 720 to around 500 K",
        "positive": "Phonon dynamics for light dark matter detection: The search for low-mass dark matter (DM) goes in parallel with the\nidentification of new detection channels and the development of suitable\ndetectors. Detection of the resulting small energy depositions is challenging:\nit requires extremely high sensitivity, only achievable by cryogenic thermal\ndetectors, which might be put to the limit. Understanding the processes which\ncan limit performances of these detectors can be thus crucial for evaluating\nthe feasibility of the proposed new detection schemes and to design the\ndetectors and tune their performance. In this paper we focus on a promising\ndetection scheme, the excitation of single optical phonons in polar materials,\nto evaluate one of the possible limiting factors of cryogenic thermal\ndetectors, i.e. the phonon dynamics in the target/absorber. We present a\ndetailed theoretical analysis, within an entirely ab initio scheme, of the\ndownconversion and propagation processes undergone by optical phonons, created\nby the interaction of a low-mass DM particle in an Al2O3 target, until they\nreach the interface with a phonon Al collector. After a preliminary\nmethodological survey that reveals the limitations of any Relaxation Time\nApproximation based method, we developed a 3D beyond-RTA phonon Monte Carlo\nthat allowed us to introduce the spatial dimension of the device and address\nquestions about impact of target size and scattering position. We analyse also\nthe effect of the phonon energy and wavevector and show that isotopes can,\nperhaps counterintuitively, result in a larger heat flux by providing transport\nchannels of higher velocities, thus favoring detection. Our results suggest\nthat, though challenging, the direct detection of light DM via athermal phonon\ngeneration appears feasible, and that the phonon downconversion followed by\nquasi-ballistic propagation does not appear to be a major bottleneck in terms\nof reducing the signal."
    },
    {
        "anchor": "Anisotropic Effect of Dipolar Interaction in Ordered Ensembles of\n  Nanoparticles: We implement extensive computer simulations to investigate the hysteresis\ncharacteristics in the ordered arrays ($l^{}_x\\times l^{}_y$) of magnetic\nnanoparticles as a function of aspect ratio $A^{}_r=l^{}_y/l^{}_x$, dipolar\ninteraction strength $h^{}_d$, and external magnetic field directions. We have\nconsidered the aligned anisotropy case, $\\alpha$ is the orientational angle. It\nprovides an elegant en route to unearth the explicit role of anisotropy and\ndipolar interaction on the hysteresis response in such a versatile system. The\nsuperparamagnetic character is dominant with weak dipolar interaction\n($h^{}_d\\leq0.2$), resulting in the minimal hysteresis loop area. Remarkably,\nthe double-loop hysteresis emerges even with moderate interaction strength\n($h^{}_d\\approx0.4$), reminiscent of antiferromagnetic coupling. These features\nare strongly dependent on $\\alpha$ and $A^{}_r$. Interestingly, the hysteresis\nloop area increases with $h^{}_d$, provided $A^{}_r$ is enormous, and the\nexternal magnetic field is along the $y$-direction. The coercive field\n$\\mu^{}_oH^{}_c$, remanent magnetization $M^{}_r$, and the heat dissipation\n$E^{}_H$ also depend strongly on these parameters. Irrespective of the external\nfield direction and weak dipolar interaction ($h^{}_d\\leq0.4$), there is an\nincrease in $\\mu^{}_oH^{}_c$ with $h^{}_d$ for a fixed $\\alpha$ and\n$A^{}_r\\leq4.0$. The dipolar interaction also elevates $M^{}_r$ as long as\n$A^{}_r$ is huge and the field is along the $y$-direction. $E^{}_H$ is minimal\nfor negligible and weak dipolar interaction, irrespective of $A^{}_r$,\n$\\alpha$, and the field directions. Notably, the magnetic interaction enhances\n$E^{}_H$ if $A^{}_r$ is enormous and the magnetic field is along the long axis\nof the system. These results are beneficial in various applications of interest\nsuch as digital data storage, spintronics, etc.",
        "positive": "Formation and stability of self-assembled coherent islands in highly\n  mismatched heteroepitaxy: We study the energetics of island formation in Stranski-Krastanow growth\nwithin a parameter-free approach. It is shown that an optimum island size\nexists for a given coverage and island density if changes in the wetting layer\nmorphology after the 3D transition are properly taken into account. Our\napproach reproduces well the experimental island size dependence on coverage,\nand indicates that the critical layer thickness depends on growth conditions.\nThe present study provides a new explanation for the (frequently found) rather\nnarrow size distribution of self-assembled coherent islands."
    },
    {
        "anchor": "Interrelation of epitaxial strain and oxygen deficiency in\n  La0.7Ca0.3MnO3-\u03b4 thin films: The interrelation between the epitaxial strain and oxygen deficiency in\nLa0.7Ca0.3MnO3-{\\delta} thin films was studied in terms of structural and\nfunctional properties. The films with a thickness of 1000{\\AA} were prepared\nusing a PLD system equipped with a RHEED facility and a pyrometric film\ntemperature control. The epitaxial strain and the oxygen deficiency in the\nsamples were systematically modified using three different substrates: SrTiO3,\n(LaAlO3)0.3-(Sr2AlTaO6)0.7 and LaSrAlO4, and four different oxygen pressures\nduring film growth ranging from 0.27mbar to 0.1mbar. It could be demonstrated\nthat the oxygen incorporation depends on the epitaxial strain: oxygen vacancies\nwere induced to accommodate tensile strain whereas the compressive strain\nsuppressed the generation of oxygen vacancies.",
        "positive": "Atomistic spin model simulations of magnetic nanomaterials: Atomistic modelling of magnetic materials provides unprecedented detail about\nthe underlying physical processes that govern their macroscopic properties, and\nallows the simulation of complex effects such as surface anisotropy, ultrafast\nlaser-induced spin dynamics, exchange bias, and mi- crostructural effects. Here\nwe present the key methods used in atomistic spin models which are then applied\nto a range of magnetic problems. We detail the parallelisation strategies used\nwhich enable the routine simulation of extended systems with full atomistic\nresolution."
    },
    {
        "anchor": "Full vibrational characterization of ethylene adsorption on\n  Si(001)-(2x1) by a combined theoretical and experimental approach: The vibrational and structural properties of a single-domain Si(001)-(2x1)\nsurface upon ethylene adsorption have been studied by density functional\ncluster calculations and high-resolution electron energy loss spectroscopy. The\ndetailed analysis of the theoretically and the experimentally determined\nvibrational frequencies reveals two coexisting adsorbate configurations. The\nmajority ethylene species is di-sigma bonded to the two Si atoms of a single\nSi-Si dimer. The local symmetry of this adsorption complex for ethylene\nsaturation is reduced to C2 as determined by surface selection rules for the\nvibrational excitation process. The symmetry reduction includes the rotation of\nthe C-C bond around the surface normal and the twist of the methylene groups\naround the C-C axis. Experimentally 17 ethylene-derived modes are found and\nassigned for the majority and the minority species based on a comparison with\ncalculated vibrational frequencies. The minority species which can account up\nto 14 % of the total ethylene coverage is spectroscopically identified for the\nfirst time. It is assigned to ethylene molecules di-sigma bonded to two\nadjacent Si-Si dimers (in an end-bridge configuration). One part of these\nminority species desorbs molecularly at 665 K, about 50 K higher than the\nmajority species, whereas the remaining part dissociates to adsorbed acetylene\nat temperatures around 630 K. For the latter a di-sigma end-bridge like bonding\nconfiguration is proposed based on a comparison of the vibrational spectra with\ndata for adsorbed acetylene on Si(100)-(2x1).",
        "positive": "Structural Trends Interpretation of the Metal-to-Semiconductor\n  Transition in Deformed Carbon Nanotubes: Two mechanisms that drive metal-to-semiconductor transitions in single-walled\ncarbon nanotubes are theoretically analyzed through a simple tight-binding\nmodel. By considering simple structural trends, the results demonstrate that\nmetal-to-semiconductor transitions can be induced more readily in metallic\nzigzag nanotubes than in armchair nanotubes. Furthermore, it is shown that both\nmechanisms have the effect of making the two originally equivalent sublattices\nphysically distinguishable."
    },
    {
        "anchor": "Argon Assisted Growth of Epitaxial Graphene on Cu(111): The growth of graphene by catalytic decomposition of ethylene on Cu(111) in\nan ultra-high vacuum system was investigated with low energy electron\ndiffraction, low energy electron microscopy, and atomic force microscopy.\nAttempts to form a graphene overlayer using ethylene at pressures as high as 10\nmTorr and substrate temperatures as high as 900 $^\\circ$C resulted in almost no\ngraphene growth. By using an argon overpressure, the growth of epitaxial\ngraphene on Cu(111) was achieved. The suppression of graphene growth without\nthe use of an argon overpressure is attributed to Cu sublimation at elevated\ntemperatures. During the initial stages of growth, a random distribution of\nrounded graphene islands is observed. The predominant rotational orientation of\nthe islands is within $\\pm1^\\circ$ of the Cu(111) substrate lattice.",
        "positive": "Growth of Equally-Sized Insulin Crystals: Guidelines for growing insulin crystals of a uniform size are formulated and\ntested experimentally. A simple theoretical model based on the balance of\nmatter predicts the time evolution of the crystal size and supersaturation. The\ntime dependence of the size is checked experimentally. The experimental\napproach decouples crystal nucleation and growth processes according to the\nclassical nucleation-growth-separation principle. Strict control over the\nnucleation process is exerted. Crystalline substance dispersity is\npredetermined during the nucleation stage of a batch crystallization process.\nTo avert nutrition competition during the crystal growth stage, the number\ndensity of nucleated crystals is preset to be optimal."
    },
    {
        "anchor": "Ewald methods for polarizable surfaces with application to hydroxylation\n  and hydrogen bonding on the (012) and (001) surfaces of alpha-Fe2O3: We present a clear and rigorous derivation of the Ewald-like method for\ncalculation of the electrostatic energy of the systems infinitely periodic in\ntwo-dimensions and of finite size in the third dimension (slabs) which is\nsignificantly faster than existing methods. Molecular dynamics simulations\nusing the transferable/polarizable model by Rustad et al. were applied to study\nthe surface relaxation of the nonhydroxylated, hydroxylated, and solvated\nsurfaces of alpha-Fe2O3 (hematite). We find that our nonhydroxylated structures\nand energies are in good agreement with previous LDA calculations on\nalpha-alumina by Manassidis et al. [Surf. Sci. Lett. 285, L517, 1993]. Using\nthe results of molecular dynamics simulations of solvated interfaces, we define\nend-member hydroxylated-hydrated states for the surfaces which are used in\nenergy minimization calculations. We find that hydration has a small effect on\nthe surface structure, but that hydroxylation has a significant effect. Our\ncalculations, both for gas-phase and solution-phase adsorption, predict a\ngreater amount of hydroxylation for the (012) surface than for the (001)\nsurface. Our simulations also indicate the presence of four-fold coordinated\niron ions on the (001) surface.",
        "positive": "Low Temperature Investigation of Electrical Conduction in Polysilicon:\n  Simulation and Experiment: Investigation of electrical conduction in polysilicon nanowires (polySiNW)\nwith nanograins (5 to 20nm), based on Monte Carlo (MC) simulations and\nelectrical measurements from 4K to 300K are presented. Some irregular Coulomb\nOscillations (CO) are observed at temperatures lower than 200K showing several\nperiod widths due to the random distribution in grain size (5-20nm). A\nremarkable result consists in more effective oscillations observed at\nintermediate range of temperatures (between 25K and 150K) and high drain\nvoltages. The temperature dependence of COs is explained by the fact that in a\nmultiple asymmetric dot system at low temperature, COs are observed not at the\nlowest but at an intermediate temperature range, whereas the drain voltage\ndependence is due to an enhanced non-resonant tunneling. MC simulations have\nconfirmed experimental observations."
    },
    {
        "anchor": "Comparison of the properties of GaN grown on complex Si-based structures: With the aim of investigating the possible integration of opto-electronic\ndevices, epitaxial GaN layers have been grown on Si(111) SOI and on\nSi/CoSi2/Si(111) using metalorganic chemical vapor deposition. The samples are\nfound to possess a highly oriented wurtzite structure, a uniform thickness and\nabrupt interfaces. The epitaxial orientation is determined as\nGaN(0001)//Si(111), GaN[1120]//Si[110] and GaN[1010]//Si[112], and the GaN\nlayer is tensily strained in the direction parallel to the interface. According\nto Rutherford backscattering/channeling spectrometry and (0002) rocking curves,\nthe crystalline quality of GaN on Si(111) SOI is better than that of GaN on\nsilicide. Room-temperature photoluminescence of GaN/SOI reveals a strong\nnear-bandedge emission at 368 nm (3.37 eV) with an FWHM of 59 meV.",
        "positive": "Halogens in the synthesis of colloidal semiconductor nanocrystals: In this review, we highlight the role of halogenated compounds in the\ncolloidal synthesis of nanostructured semiconductors. Halogen-containing\nmetallic salts used as precursors and halogenated hydrocarbons used as ligands\nallow stabilizing different shapes and crystal phases, and enable the formation\nof colloidal systems with different dimensionality. We summarize recent reports\non the tremendous influence of these compounds on the physical properties of\nnanocrystals, like field-effect mobility and solar cell performance and outline\nmain analytical methods for the nanocrystal surface control."
    },
    {
        "anchor": "Power Law Multi-Scaling of Material Strength: Power law is one of the the simplest forms of the relationship between\ndifferent variables of a system. It leads naturally to the introduction of\ncompound parameters describing physical properties of the system. Often one of\nthe variables of interest is the object dimension, or time. The prevalence of a\nsimple power law over the entire range of dimensions or times can be helpfully\ninterpreted as size or time independence of the corresponding compound physical\nparameter of the system. However, it is also often found that a simple power\nlaw only persists for some extreme values, e.g. for very large and/or small\nsizes, or very short or long times. Transitions between regimes of different\npower law asymptotic behaviour are encountered frequently in the description of\na wide variety of physical systems. While asymptotic power law behaviour may\noften be readily predicted, e.g. on dimensional grounds, the evaluation of the\nrelationship between system parameters in the transition range usually requires\nlaborious detailed solution. To obviate this difficulty we introduce, on rather\ngeneral basis, something we refer to as the merging, or 'knee' function. The\nfunction possesses sufficient flexibility to describe transitions of various\nsharpness. To demonstrate its usefuness, the merging function is applied to a\nvariety of well-known scaling laws in the mechanics and strength of materials\nand structures.",
        "positive": "Grain Boundary Segregation Transitions and Critical Phenomena in Binary\n  Regular Solutions: A Systematics of Complexion Diagrams with Universal\n  Characters: A systematics of grain boundary (GB) segregation transitions and critical\nphenomena has been derived to expand the classical GB segregation theory. Using\ntwist GBs as an example, this study uncovers when GB layering vs. prewetting\ntransitions should occur and how they are related to one another. Moreover, a\nnovel descriptor, normalized segregation strength (phi_seg), is introduced. It\ncan represent several factors that control GB segregation, including strain and\nbond energies, as well as misorientation for small-angle GBs (in a mean-field\napproximation), which had to be treated separately in prior models. In a strong\nsegregation system with a large phi_seg, first-order layering transitions occur\nat low temperatures and become continuous above GB roughing temperatures. With\nreducing phi_seg, the layering transitions gradually merge and finally lump\ninto prewetting transitions without quantized layer numbers, akin to Cahn's\ncritical-point wetting model. Furthermore, GB complexion diagrams with\nuniversal characters are constructed as the GB counterpart to the classical\nexemplar of Pelton-Thompson regular-solution binary bulk phase diagrams."
    },
    {
        "anchor": "Material, size and environment dependence of plasmon-induced hot\n  carriers in metallic nanoparticles: Harnessing hot electrons and holes resulting from the decay of localized\nsurface plasmons in nanomaterials has recently led to new devices for\nphotovoltaics, photocatalysis and optoelectronics. Properties of hot carriers\nare highly tunable and in this work we investigate their dependence on the\nmaterial, size and environment of spherical metallic nanoparticles. In\nparticular, we carry out theoretical calculations of hot carrier generation\nrates and energy distributions for six different plasmonic materials (Na, K,\nAl, Cu, Ag and Au). The plasmon decay into hot electron-hole pairs is described\nvia Fermi's Golden Rule using the quasistatic approximation for optical\nproperties and a spherical well potential for the electronic structure. We\npresent results for nanoparticles with diameters up to 40 nm, which are\nembedded in different dielectric media. We find that small nanoparticles with\ndiameters of 16 nm or less in media with large dielectric constants produce\nmost hot carriers. Among the different materials, Na, K and Au generate most\nhot carriers. We also investigate hot-carrier induced water splitting and find\nthat simple-metal nanoparticles are useful for initiating the hydrogen\nevolution reaction, while transition-metal nanoparticles produce dominantly\nholes for the oxygen evolution reaction.",
        "positive": "Ni$_{80}$Fe$_{20}$ Nanotubes with Optimized Spintronic Functionalities\n  Prepared by Atomic Layer Deposition: Permalloy Ni$_{80}$Fe$_{20}$ is one of the key magnetic materials in the\nfield of magnonics. Its potential would be further unveiled if it could be\ndeposited in three dimensional (3D) architectures of sizes down to the\nnanometer. Atomic Layer Deposition, ALD, is the technique of choice for\ncovering arbitrary shapes with homogeneous thin films. Early successes with\nferromagnetic materials include nickel and cobalt. Still, challenges in\ndepositing ferromagnetic alloys reside in the synthesis via decomposing the\nconsituent elements at the same temperature and homogeneously. We report\nplasma-enhanced ALD to prepare permalloy Ni$_{80}$Fe$_{20}$ thin films and\nnanotubes using nickelocene and iron(III) tert-butoxide as metal precursors,\nwater as the oxidant agent and an in-cycle plasma enhanced reduction step with\nhydrogen. We have optimized the ALD cycle in terms of Ni:Fe atomic ratio and\nfunctional properties. We obtained a Gilbert damping of 0.013, a resistivity of\n28 $\\mu\\Omega$cm and an anisotropic magnetoresistance effect of 5.6 $\\%$ in the\nplanar thin film geometry. We demonstrate that the process also works for\ncovering GaAs nanowires, resulting in permalloy nanotubes with high aspect\nratios and diameters of about 150 nm. Individual nanotubes were investigated in\nterms of crystal phase, composition and spin-dynamic response by microfocused\nBrillouin Light Scattering. Our results enable NiFe-based 3D spintronics and\nmagnonic devices in curved and complex topology operated in the GHz frequency\nregime."
    },
    {
        "anchor": "Improving realistic material property prediction using domain adaptation\n  based machine learning: Materials property prediction models are usually evaluated using random\nsplitting of datasets into training and test datasets, which not only leads to\nover-estimated performance due to inherent redundancy, typically existent in\nmaterial datasets, but also deviate away from the common practice of materials\nscientists: they are usually interested in predicting properties for a known\nsubset of related out-of-distribution (OOD) materials rather than a universally\ndistributed samples. Feeding such target material formulas/structures to the\nmachine learning models should improve the prediction performance while most\ncurrent machine learning (ML) models neglect this information. Here we propose\nto use domain adaptation (DA) to enhance current ML models for property\nprediction and evaluate their performance improvements in a set of five\nrealistic application scenarios. Our systematic benchmark studies show that\nthere exist DA models that can significantly improve the OOD test set\nprediction performance while standard ML models and most of the other DAs\ncannot improve or even deteriorate the performance. Our benchmark datasets and\nDA code can be freely accessed at https://github.com/Little-Cheryl/MatDA.",
        "positive": "Graphene in periodically alternating magnetic field: unusual\n  quantization of the anomalous Hall effect: We study the energy spectrum and electronic properties of graphene in a\nperiodic magnetic field of zero average with a symmetry of triangular lattice.\nThe periodic field leads to formation of a set of minibands separated by gaps,\nwhich can be manipulated by external field. The Berry phase, related to the\nmotion of electrons in $k$ space, and the corresponding Chern numbers\ncharacterizing topology of the energy bands are calculated analytically and\nnumerically. In this connection, we discuss the anomalous Hall effect in the\ninsulating state, when the Fermi level is located in the minigap. The results\nof calculations show that in the model of gapless Dirac spectrum of graphene\nthe anomalous Hall effect can be treated as a sum of fractional quantum\nnumbers, related to the nonequivalent Dirac points."
    },
    {
        "anchor": "Quantum effects on the loss function of Pb(111) thin films: an ab initio\n  study: A theoretical study of the surface energy-loss function of freestanding\nPb(111) thin films is presented, starting from the single monolayer case. The\ncalculations are carried applying the linear response theory, with inclusion of\nthe electron band structure by means of a first-principles pseudopotential\napproach using a supercell scheme. Quantum-size effects on the plasmon modes of\nthe thinnest films are found in qualitative agreement with previous work based\non the jellium model. For thicker films, results show a dispersionless mode at\nall thicknesses, in agreeement with electron energy-loss measurements. For\nsizeable values of the momentum, the raising of the surface plasmon with\nincreasing thickness is retrieved.",
        "positive": "First principles determination of the Peierls stress of the shuffle\n  screw dislocation in silicon: The Peierls stress of the a/2<110> screw dislocation belonging to the shuffle\nset is calculated for silicon using density functional theory. We have checked\nthe effect of boundary conditions by using two models, the supercell method\nwhere one considers a periodic array of dislocations, and the cluster method\nwhere a single dislocation is embedded in a small cluster. The Peierls stress\nis underestimated with the supercell and overestimated with the cluster. These\ncontributions have been calculated and the Peierls stress is determined in the\nrange between 2.4 x 10-2 and 2.8 x 10-2 eV {\\AA}-3. When moving, the\ndislocation follows the {111} plane going through a low energy metastable\nconfiguration and never follows the 100 plane, which includes a higher energy\nmetastable core configuration."
    },
    {
        "anchor": "Automated optimization of convergence parameters in plane wave density\n  functional theory calculations via a tensor decomposition-based uncertainty\n  quantification: First principles approaches have revolutionized our ability in using\ncomputers to predict, explore and design materials. A major advantage commonly\nassociated with these approaches is that they are fully parameter free.\nHowever, numerically solving the underlying equations requires to choose a set\nof convergence parameters. With the advent of high-throughput calculations it\nbecomes exceedingly important to achieve a truly parameter free approach.\nUtilizing uncertainty quantification (UQ) and tensor decomposition we derive a\nnumerically highly efficient representation of the statistical and systematic\nerror in the multidimensional space of the convergence parameters. Based on\nthis formalism we implement a fully automated approach that requires as input\nthe target accuracy rather than convergence parameters. The performance and\nrobustness of the approach are shown by applying it to a large set of elements\ncrystallizing in a cubic fcc lattice.",
        "positive": "Initiation and stagnation of room temperature grain coarsening in\n  cyclically strained gold films: Despite the large number of experiments demonstrating that grains in a\nmetallic material can grow at room temperature due to applied mechanical load,\nthe mechanisms and the driving forces responsible for mechanically induced\ngrain coarsening are still not understood. Here we present a systematic study\nof room temperature grain coarsening induced by cyclic strain in thin\npolymer-supported gold films. By means of detailed electron backscatter\ndiffraction analysis we were able to capture both the growth of individual\ngrains and the evolution of the whole microstructure on the basis of\nstatistical data over thousands of grains. The experimental data are reported\nfor three film thicknesses with slightly different microstructures and three\ndifferent amplitudes of cyclic mechanical loading. Although different kinds of\ngrain size evolution with increasing cycle number are observed depending on\nfilm thickness and strain amplitude, a single model based on a thermodynamic\ndriving force is shown to be capable to explain initiation and stagnation of\ngrain coarsening in all cases. The main implication of the model is that the\ngrains having lower individual yield stress are coarsening preferentially.\nBesides, it is demonstrated that the existence of local shear stresses imposed\non a grain boundary is not a necessary requirement for room-temperature grain\ncoarsening."
    },
    {
        "anchor": "Searching for Materials with High Refractive Index and Wide Band Gap: A\n  First-Principles High-Throughput Study: Materials combining both a high refractive index and a wide band gap are of\ngreat interest for optoelectronic and sensor applications. However, these two\nproperties are typically described by an inverse correlation with high\nrefractive index appearing in small gap materials and vice-versa. Here, we\nconduct a first-principles high-throughput study on more than 4000\nsemiconductors (with a special focus on oxides). Our data confirm the general\ninverse trend between refractive index and band gap but interesting outliers\nare also identified. The data are then analyzed through a simple model\ninvolving two main descriptors: the average optical gap and the effective\nfrequency. The former can be determined directly from the electronic structure\nof the compounds, but the latter cannot. This calls for further analysis in\norder to obtain a predictive model. Nonetheless, it turns out that the negative\neffect of a large band gap on the refractive index can counterbalanced in two\nways: (i) by limiting the difference between the direct band gap and the\naverage optical gap which can be realized by a narrow distribution in energy of\nthe optical transitions and (ii) by increasing the effective frequency which\ncan be achieved through either a high number of transitions from the top of the\nvalence band to the bottom of the conduction or a high average probability for\nthese transitions.\n  Focusing on oxides, we use our data to investigate how the chemistry\ninfluences this inverse relationship and rationalize why certain classes of\nmaterials would perform better. Our findings can be used to search for new\ncompounds in many optical applications both in the linear and non-linear regime\n(waveguides, optical modulators, laser, frequency converter, etc.).",
        "positive": "Drug delivery with carbon nanotubes for in vivo cancer treatment: Chemically functionalized single-walled carbon nanotubes (SWNTs) have shown\npromise in tumor targeted accumulation in mice and exhibit biocompatibility,\nexcretion and little toxicity. Here, we demonstrate in-vivo SWNT drug delivery\nfor tumor suppression in mice. We conjugate paclitaxel (PTX), a widely used\ncancer chemotherapy drug to branched polyethylene-glycol (PEG) chains on SWNTs\nvia a cleavable ester bond to obtain a water soluble SWNT-paclitaxel conjugate\n(SWNT-PTX). SWNT-PTX affords higher efficacy in suppressing tumor growth than\nclinical Taxol in a murine 4T1 breast-cancer model, owing to prolonged blood\ncirculation and 10-fold higher tumor PTX uptake by SWNT delivery likely through\nenhanced permeability and retention (EPR). Drug molecules carried into the\nreticuloendothelial system are released from SWNTs and excreted via biliary\npathway without causing obvious toxic effects to normal organs. Thus, nanotube\ndrug delivery is promising for high treatment efficacy and minimum side effects\nfor future cancer therapy with low drug doses."
    },
    {
        "anchor": "Achieving control of in-plane elastic waves: We derive the elastic properties of a cylindrical cloak for in-plane coupled\nshear and pressure waves. The cloak is characterized by a rank 4 elasticity\ntensor with 16 spatially varying entries which are deduced from a geometric\ntransform. Remarkably, the Navier equations retain their form under this\ntransform, which is generally untrue [Milton et al., New J. Phys. 8, 248\n(2006)]. We numerically check that clamped and freely vibrating obstacles\nlocated inside the neutral region are cloaked disrespectful of the frequency\nand the polarization of an incoming elastic wave.",
        "positive": "Perfect Spin-filtering and Giant Magnetoresistance with Fe-terminated\n  Graphene Nanoribbon: Spin-dependent electronic transport properties of Fe-terminated zig-zag\ngraphene nanoribbons (zGNR) have been studied using first-principles transport\nsimulations. The spin configuration of proposed zGNR junction can be controlled\nwith external magnetic field, and the tunneling junction show MR>1000 at small\nbias and is a perfect spin-filter by applying uniform external magnetic filed\nat small bias."
    },
    {
        "anchor": "Realizable response matrices of multiterminal electrical, acoustic, and\n  elastodynamic networks at a given frequency: We give a complete characterization of the possible response matrices at a\nfixed frequency of n-terminal electrical networks of inductors, capacitors,\nresistors and grounds, and of n-terminal discrete linear elastodynamic networks\nof springs and point masses, both in the three-dimensional case and in the\ntwo-dimensional case. Specifically we construct networks which realize any\nresponse matrix which is compatible with the known symmetry properties and\nthermodynamic constraints of response matrices. Due to a mathematical\nequivalence we also obtain a characterization of the response matrices of\ndiscrete acoustic networks.",
        "positive": "Implementation of screened hybrid functionals based on the Yukawa\n  potential within the LAPW basis set: The implementation of screened hybrid functionals into the WIEN2k code, which\nis based on the LAPW basis set, is reported. The Hartree-Fock exchange energy\nand potential are screened by means of the Yukawa potential as proposed by\nBylander and Kleinman [Phys. Rev. B 41, 7868 (1990)] for the calculation of the\nelectronic structure of solids with the screened-exchange local density\napproximation. Details of the formalism, which is based on the method of\nMassidda, Posternak, and Baldereschi [Phys. Rev. B 48, 5058 (1993)] for the\nunscreened Hartree-Fock exchange are given. The results for the\ntransition-energy and structural properties of several test cases are\npresented. Results of calculations of the Cu electric-field gradient in Cu2O\nare also presented, and it is shown that the hybrid functionals are much more\naccurate than the standard local-density or generalized gradient\napproximations."
    },
    {
        "anchor": "Role of Quantum-Confinement in Anatase Nanosheets: Despite most of the applications of anatase nanostructures rely on\nphotoexcited charge processes, yet profound theoretical understanding of\nfundamental related properties is lacking. Here, by means of ab initio ground\nand excited-state calculations, we reveal, in an unambiguous way, the role of\nquantum confinement effect and of the surface orientation, on the electronic\nand optical properties of anatase nanosheets (NSs). The presence of bound\nexcitons extremely localized along the (001) direction, whose existence has\nbeen recently proven also in anatase bulk, explains the different optical\nbehavior found for the two orientations (001) and (101) when the NS thickness\nincreases. We suggest also that the almost two-dimensional nature of these\nexcitons can be related to the improved photoconversion efficiency observed\nwhen a high percentage of (001) facet is present in anatase nanocrystals.",
        "positive": "Tailoring a two-dimensional electron gas at the LaAlO3/SrTiO3 (001)\n  interface by epitaxial strain: Recently a metallic state was discovered at the interface between insulating\noxides, most notably LaAlO3 and SrTiO3. Properties of this two-dimensional\nelectron gas (2DEG) have attracted significant interest due to its potential\napplications in nanoelectronics. Control over this carrier density and mobility\nof the 2DEG is essential for applications of these novel systems, and may be\nachieved by epitaxial strain. However, despite the rich nature of strain\neffects on oxide materials properties, such as ferroelectricity, magnetism, and\nsuperconductivity, the relationship between the strain and electrical\nproperties of the 2DEG at the LaAlO3/SrTiO3 heterointerface remains largely\nunexplored. Here, we use different lattice constant single crystal substrates\nto produce LaAlO3/SrTiO3 interfaces with controlled levels of biaxial epitaxial\nstrain. We have found that tensile strained SrTiO3 destroys the conducting\n2DEG, while compressively strained SrTiO3 retains the 2DEG, but with a carrier\nconcentration reduced in comparison to the unstrained LaAlO3/SrTiO3 interface.\nWe have also found that the critical LaAlO3 overlayer thickness for 2DEG\nformation increases with SrTiO3 compressive strain. Our first-principles\ncalculations suggest that a strain-induced electric polarization in the SrTiO3\nlayer is responsible for this behavior. It is directed away from the interface\nand hence creates a negative polarization charge opposing that of the polar\nLaAlO3 layer. This both increases the critical thickness of the LaAlO3 layer,\nand reduces carrier concentration above the critical thickness, in agreement\nwith our experimental results. Our findings suggest that epitaxial strain can\nbe used to tailor 2DEGs properties of the LaAlO3/SrTiO3 heterointerface."
    },
    {
        "anchor": "Stark Ionization of Atoms and Molecules within Density Functional\n  Resonance Theory: We show that the energetics and lifetimes of resonances of finite systems\nunder an external electric field can be captured by Kohn--Sham density\nfunctional theory (DFT) within the formalism of uniform complex scaling.\nProperties of resonances are calculated self-consistently in terms of complex\ndensities, potentials and wavefunctions using adapted versions of the known\nalgorithms from DFT. We illustrate this new formalism by calculating ionization\nrates using the complex-scaled local density approximation and exact exchange.\nWe consider a variety of atoms (H, He, Li and Be) as well as the hydrogen\nmolecule. Extensions are briefly discussed.",
        "positive": "Colossal Seebeck coefficient in Aurivillius Phase-Perovskite Oxide\n  Composite: We propose an inexpensive scalable approach for achieving extremely high\nvalues of Seebeck coefficient ($\\alpha$) by exploiting the natural superlattice\nstructure in Aurivillius phase oxides. In particular, we report an $\\alpha\n\\approx $ 319\\,mV/K at 300\\,K in a composite of Aurivillius phase compound\nSrBi$_4$Ti$_4$O$_{15}$ (as a matrix) and a perovskite phase material (e.g.,\nLa$_{0.7}$Sr$_{0.3}$MnO$_3$ or, La$_{0.7}$Sr$_{0.3}$CoO$_3$ as filler). Such a\ncolossal value of $\\alpha$ can be attributed to contributions from the enhanced\ndensity of states due to the effective low dimensional character of Bi$_2$O$_2$\nlayer. The corresponding thermal conductivity ($\\kappa$) and the electrical\nconductivity ($\\sigma$) lies in the range 0.7 - 1.25 W/m-K and 10 - 100\n$\\mu$S/m, respectively at 300\\,K. Attributed to the high $\\alpha$ values, such\noxide composites can be used as thermopile sensors and highly sensitive\nbolometric applications. We anticipate that the demonstration of colossal\n$\\alpha$ in oxide composites using a simple synthesis strategy also sets the\nstage for future material innovations for high temperature thermoelectric\napplications."
    },
    {
        "anchor": "Thermal laser evaporation of elements from across the periodic table: We propose and demonstrate that thermal laser evaporation can be applied to\nall solid, non-radioactive elements in the periodic table. By depositing thin\nfilms, we achieve growth rates exceeding 1 angstrom/s with output laser powers\nless than 500 W, using identical beam parameters for many different elements.\nThe source temperature is found to vary linearly with laser power within the\nexamined power range. High growth rates are possible using free-standing\nsources for most of the elements tested, eliminating the need for crucibles.",
        "positive": "Polarization selectivity of aloof-beam electron energy-loss spectroscopy\n  in one-dimensional ZnO nanorods: Orientation dependent electronic properties of wurtzite zinc oxide nanorods\nare characterized by aloof beam electron energy-loss spectroscopy (EELS)\ncarried out in a scanning transmission electron microscope (STEM). The two key\ncrystal orientation differentiating transitions specific to the in-plane (13.0\neV) and out-of-plane (11.2 eV) directions with respect to the wurtzite\nstructure are examined by first principles density-functional theory\ncalculations. We note some degree of orientation dependence at the onset of\ndirect band gap transition near 3.4 eV. We demonstrate that good polarization\nselectivity can be achieved by placing the electron probe at different\nlocations around the specimen with increasing impact parameter while keeping\nthe beam-specimen orientation fixed. The observed results are qualitatively\nelucidated in terms of the perpendicular electric fields generated by the fast\nelectron (60 kV) used in the microscope. The fact that good polarization\nselectivity can be achieved by aloof beam EELS without the requirement of\nsample reorientation is an attractive aspect from the characterization method\npoint of view in the STEM-EELS community."
    },
    {
        "anchor": "Selective-area van der Waals epitaxy of h-BN/graphene heterostructures\n  via He$^{+}$ irradiation-induced defect-engineering in 2D substrates: The combination of two-dimensional (2D) materials into heterostructures\nenabled the formation of atomically thin devices with designed properties. To\nachieve a high density, bottom-up integration, the growth of these 2D\nheterostructures via van der Waals epitaxy (vdWE) is an attractive alternative\nto the currently mostly employed mechanical transfer, which is still\nproblematic in terms of scaling and reproducibility. However, controlling the\nlocation of the nuclei formation remains a key challenge in vdWE. Here, we use\na focused He ion beam for a deterministic placement of defects in graphene\nsubstrates, which act as preferential nucleation sites for the growth of\ninsulating, 2D hexagonal boron nitride (h-BN). We demonstrate a mask-free,\nselective-area vdWE (SAvdWE), where nucleation yield and crystal quality of\nh-BN is controlled by the ion beam parameter used for the defect formation.\nMoreover, we show that h-BN grown via SAvdWE has electron tunneling\ncharacteristics comparable to those of mechanically transferred layers, thereby\nlying the foundation for a reliable, high density array fabrication of 2D\nheterostructures for device integration via defect engineering in 2D\nsubstrates.",
        "positive": "Chiral Polarization Textures Induced by the Flexoelectric Effect in\n  Ferroelectric Nanocylinders: Polar chiral structures have recently attracted much interest within the\nscientific community, as they pave the way towards innovative device concepts\nsimilar to the developments achieved in nanomagnetism. Despite the growing\ninterest, many fundamental questions related to the mechanisms controlling the\nappearance and stability of ferroelectric topological structures remain open.\nIn this context, ferroelectric nanoparticles provide a flexible playground for\nsuch investigations. Here, we present a theoretical study of ferroelectric\npolar textures in a cylindrical core-shell nanoparticle. The calculations\nreveal a chiral polarization structure containing two oppositely oriented\ndiffuse axial domains located near the cylinder ends, separated by a region\nwith a zero-axial polarization. We name this polarization configuration\n\"flexon\" to underline the flexoelectric nature of its axial polarization.\nAnalytical calculations and numerical simulation results show that the flexon's\nchirality can be switched by reversing the sign of the flexoelectric\ncoefficient. Furthermore, the anisotropy of the flexoelectric coupling is found\nto critically influence the polarization texture and domain morphology. The\nflexon rounded shape, combined with its distinct chiral properties and the\nlocalization nature near the surface, are reminiscent of Chiral Bobber\nstructures in magnetism. In the azimuthal plane, the flexon displays the\npolarization state of a vortex with an axially polarized core region, i.e., a\nmeron. The flexoelectric effect, which couples the electric polarization and\nelastic strain gradients, plays a determining role in the stabilization of\nthese chiral states. We discuss similarities between this interaction and the\nrecently predicted ferroelectric Dyzaloshinskii-Moriya interaction leading to\nchiral polarization states."
    },
    {
        "anchor": "Self-hybridization and tunable magnon-magnon coupling in van der Waals\n  synthetic magnets: Van der Waals magnets are uniquely positioned at the intersection between\ntwo-dimensional materials, antiferromagnetic spintronics, and magnonics. The\ninterlayer exchange interaction in these materials enables antiferromagnetic\nresonances to be accessed at GHz frequencies. Consequently, these layered\nantiferromagnets are intriguing materials out of which quantum hybrid magnonic\ndevices can be fashioned. Here, we use both a modified macrospin model and\nmicromagnetic simulations to demonstrate a comprehensive antiferromagnetic\nresonance spectra in van der Waals magnets near the ultrathin (monolayer)\nlimit. The number of optical and acoustic magnon modes, as well as the mode\nfrequencies, are found to be exquisitely sensitive to the number of layers. We\ndiscover a self-hybridization effect where pairs of either optical or acoustic\nmagnons are found to interact and self-hybridize through the dynamic exchange\ninteraction. This leads to characteristic avoided energy level crossings in the\nenergy spectra. Through simulations, we show that by electrically controlling\nthe damping of surface layers within heterostructures both the strength and\nnumber of avoided energy level crossings in the magnon spectra can be\ncontrolled.",
        "positive": "Can buckling account for the features seen in graphite's Raman spectra?: Raman scattering data were collected on graphite monochromator. Spectra were\ninterpreted in terms of the space group $P6_3mc$, a subgroup of space group\n$P6_3/mmc$. The latter has commonly been used for the interpretation of Raman\nscattering data. Space group $P6_3mc$ corresponds to the buckling of graphene\nsheets and is consistent with many spectral features. Both the first and second\norder scattering were considered. Many first order results (most notably the\nassignments of the band at 1350 and the peak at 1620 cm$^{-1}$) were found to\nagree with previous observations [Y. Kawashima and G. Katagiri, Phys. Rev. B\n\\textbf{66}, 104109 (2002)] carried out on highly oriented pyrolytic graphite\nsamples. To check the consistency of the model, symmetry analysis was applied\nto the second order spectra. Also a simple test for buckling model was done."
    },
    {
        "anchor": "Space charge dynamics in solid electrolytes with steric effect and\n  Vegard stresses: resistive switching and ferroelectric-like hysteresis of\n  electromechanical response: We performed self-consistent modelling of electrotransport and\nelectromechanical response of solid electrolyte thin films allowing for steric\neffects of mobile charged defects (ions, protons or vacancies), electron\ndegeneration and Vegard stresses. We establish correlations between the\nfeatures of the space-charge dynamics, current-voltage and bending-voltage\ncurves in the wide frequency range of applied electric voltage. The pronounced\nferroelectric-like hysteresis of bending-voltage loops and current maxima on\ndouble hysteresis current-voltage loops appear for the electron-open\nelectrodes. The double hysteresis loop with pronounced humps indicates the\nresistance switching of memristor-type. The switching occurs due to the strong\ncoupling between electronic and ionic subsystem. The sharp meta-stable maximum\nof the electron density appears near one open electrode and moves to another\none during the periodic change of applied voltage. Our results can explain the\nnature and correlation of electrical and mechanical memory effects in thin\nfilms of solid electrolytes. The analytical expression proving that the\nelectrically induced bending of solid electrolyte films can be detected by\ninterferometric methods is derived.",
        "positive": "Nucleation, imaging and motion of magnetic domain walls in cylindrical\n  nanowires: We report several procedures for the robust nucleation of magnetic domain\nwalls in cylindrical permalloy nanowires. Specific features of the magnetic\nforce microscopy contrast of such soft wires are discussed, with a view to\navoid the misinterpretation of the magnetization states. The domain walls could\nbe moved under quasistatic magnetic fields in the range 0.1--10 mT."
    },
    {
        "anchor": "Calculating the free energy of 2D materials on substrates: A method was developed to calculate the free energy of 2D materials on\nsubstrates and was demonstrated by the system of graphene and {\\gamma}-graphyne\non copper substrate. The method works at least 3 orders faster than\nstate-of-the-art algorithms, and the accuracy was tested by molecular dynamics\nsimulations, showing that the precision for calculations of the internal energy\nachieves up to 0.03% in a temperature range from 100 to 1300K. As expected, the\ncalculated the free energy of a graphene sheet on Cu (111) or Ni (111) surface\nin a temperature range up to 3000K is always smaller than the one of a\n{\\gamma}-graphyne sheet with the same number of C atoms, which is consistent\nwith the fact that growth of graphene on the substrates is much easier than\n{\\gamma}-graphyne.",
        "positive": "Modeling of Magnetoelectric Effects in Ferromagnetic/Piezoelectric Bulk\n  Composites: We discuss a model that considers the bulk composite as a homogeneous medium\nwith piezoelectric and magnetostrictive subsystems. We solve combined\nelastostatic, electrostatic and magnetostatic equations to obtain effective\ncomposite parameters (piezoelectric modules, magnetostriction factors,\ncompliances, magnetoelectric coefficients) for 3-0 and 0-3 connectivities.\nExpressions for longitudinal and transverse low-frequency magnetoelectric\nvoltage coefficients have been obtained for unclamped and clamped samples.\nVolume fractions for peak low-frequency effective magnetoelectric voltage\ncoefficient are found to be dependent on specific connectivity. Clamping leads\nto significant variation in magnetoelectric voltage coefficients. The\ncalculated magnetoelectric coefficients are compared with data."
    },
    {
        "anchor": "Band structure of MoS_2, MoSe_2, and alpha-MoTe_2: Angle-resolved\n  photoelectron spectroscopy and ab-initio calculations: In this work the complete valence-band structure of the molybdenum\ndichalcogenides MoS_2, MoSe_2, and alpha-MoTe_2 is presented and discussed in\ncomparison. The valence bands have been studied using both angle-resolved\nphotoelectron spectroscopy (ARPES) with synchrotron radiation, as well as,\nab-initio band-structure calculations. The ARPES measurements have been carried\nout in the constant-final-state (CFS) mode. The results of the calculations\nshow in general very good agreement with the experimentally determined\nvalence-band structures allowing for a clear identification of the observed\nfeatures. The dispersion of the valence bands as a function of the\nperpendicular component k_perp of the wave vector reveals a decreasing\nthree-dimensional character from MoS_2 to alpha-MoTe_2 which is attributed to\nan increasing interlayer distance in the three compounds. The effect of this\nk_perp dispersion on the determination of the exact dispersion of the\nindividual states as a function of k_parallel is discussed. By performing ARPES\nin the CFS mode the k_parallel-component for off-normal emission spectra can be\ndetermined. The corresponding k_perp-value is obtained from the symmetry of the\nspectra along the GammaA, KH, and ML line, respectively.",
        "positive": "Native Point Defects in Antiferromagnetic Phases of CrN: We present a detailed analysis of the role of native point defects in the\nantiferromagnetic (AFM) phases of bulk chromium nitride (CrN). We perform\nfirst-principles calculations using local spin-density approximation, including\nlocal interaction effects (LSDA+U), to study the two lowest energy AFM models\nexpected to describe the low-temperature phase of the material. We study the\nformation energies, lattice deformations and electronic and magnetic structure\nintroduced by native point defects. We find that, as expected, nitrogen\nvacancies are the most likely defect present in the material at low\ntemperatures. Nitrogen vacancies present different charged states in the cubic\nAFM model, exhibiting two transition energies, which could be measurable by\nthermometry experiments and could help identify the AFM structure in a sample.\nThese vacancies also result in partial spin polarization of the induced\nimpurity band, which would have interesting consequences in transport\nexperiments. Other point defects have also signature electronic and magnetic\nstructure that could be identified in scanning probe experiments."
    },
    {
        "anchor": "Premelting of Al nonperfect (111) surface: Melting behaviors of aluminum (111) perfect/nonperfect surfaces,\ncharacterized by structure ordering parameter, have been investigated by\nclassical molecular dynamics simulation with embedded atom method potential. Al\n(111) perfect surface has a superheating temperature above bulk Al melting\npoint Tm, in this work, by about 80 K. Al nonperfect (111) surface has somewhat\ndifferent local lattice structure from that on (111) perfect surface. Al\nnonperfect (111) surfaces tempt to premelt when temperature is less than Tm, in\nour simulation, by about 45 K. Aluminum atoms on the nonperfect surface zones\nare the sources of surface melting, and have larger velocities than those on\nthe perfect surface zones.",
        "positive": "Accelerating $GW$-Based Energy Level Alignment Calculations for\n  Molecule-Metal Interfaces Using a Substrate Screening Approach: The physics of electronic energy level alignment at interfaces formed between\nmolecules and metals can in general be accurately captured by the \\emph{ab\ninitio} $GW$ approach. However, the computational cost of such $GW$\ncalculations for typical interfaces is significant, given their large system\nsize and chemical complexity. In the past, approximate self-energy corrections,\nsuch as those constructed from image-charge models together with gas-phase\nmolecular level corrections, have been used to compute level alignment with\ngood accuracy. However, these approaches often neglect dynamical effects of the\npolarizability and require the definition of an image plane. In this work, we\npropose a new approximation to enable more efficient $GW$-quality calculations\nof interfaces, where we greatly simplify the calculation of the non-interacting\npolarizability, a primary bottleneck for large heterogeneous systems. This is\nachieved by first computing the non-interacting polarizability of each\nindividual component of the interface, e.g., the molecule and the metal,\nwithout the use of large supercells; and then using folding and spatial\ntruncation techniques to efficiently combine these quantities. Overall this\napproach significantly reduces the computational cost for conventional $GW$\ncalculations of level alignment without sacrificing the accuracy. Moreover,\nthis approach captures both dynamical and nonlocal polarization effects without\nthe need to invoke a classical image-charge expression or to define an image\nplane. We demonstrate our approach by considering a model system of benzene at\nrelatively low coverage on aluminum (111) surface. Although developed for such\ninterfaces, the method can be readily extended to other heterogeneous\ninterfaces."
    },
    {
        "anchor": "Infrared actuation in aligned polymer-nanotube composites: Rubber composites containing multi-walled carbon nanotubes have been\nirradiated with near infrared light to study their reversible photo-mechanical\nactuation response. We demonstrate that the actuation is reproducible across\ndiffering polymer systems. The response is directly related to the degree of\nuniaxial alignment of the nanotubes in the matrix, contracting the samples\nalong the alignment axis. The actuation stroke depends on the specific polymer\nbeing tested, however, the general response is universal for all composites\ntested. We conduct a detailed study of tube alignment induced by stress and\npropose a model for the reversible actuation behavior, based on the\norientational averaging of the local response. The single phenomenological\nparameter of this model describes the response of an individual tube to\nadsorption of low-energy photons; its experimentally determined value may\nsuggest some ideas about such a response.",
        "positive": "High Entropy Alloy CrFeNiCoCu sputtered films: High entropy alloy(HEA) films of CrFeCoNiCu were prepared by sputtering,\ntheir structure was characterized, and their electric properties measured by\ntemperature dependent Hall and Seebeck measurement. The HEA films show a solid\nsolution with fcc structure, and a 111 texture with columnar grains of widths\n15-30 nm extending through film thickness with very many twins. The residual\nelectrical resistivity of the films is around 140 {\\mu}{\\Omega}cm and the\ntemperature dependence of the resistivity is metal-like. The temperature\ncoefficient of resistivity (TCR) is small (2 ppm/K). The Hall coefficient is\npositive while the Seebeck coefficients is negative. This is interpreted as\narising from an electronic structure where the Fermi level passes through band\nstates having both holes and electrons as indicated by band structure\ncalculations. The HEA structure appears stable for annealing in vacuum, while\nannealing in an oxygen containing atmosphere causes the surface to oxidize and\ngrow a Cr-rich oxide on the surface. This is then accompanied by demixing of\nthe HEA solid solution and a decrease in residual resistance of the film."
    },
    {
        "anchor": "Internal sinks and the smoothing of the surface structure in solids\n  under irradiation: We consider in the article the influence of the irradiation and the internal\nsinks of the point defects on the rate of the flattening of the surface\nstructure in solids. The irradiation produces only the additional external\nsources of point defects(vacancies and interstitial atoms). The general system\nof equations is formulated. The solution of the system on the stationary stage\nof the process is found. It is shown that depending on the values of some\nparameters of the solid the irradiation can increase or decrease the rate of\nthe surface flattening.",
        "positive": "What X-ray absorption spectroscopy can tell us about the active state of\n  earth-abundant electrocatalysts for the oxygen evolution reaction: Chemical energy storage is an attractive solution to secure a sustainable\nenergy supply. It requires an electrocatalyst to be implemented efficiently. In\norder to rationally improve the electrocatalyst materials and thereby the\nreaction efficiency, one must reveal the nature of the electrocatalyst under\nreaction conditions, i.e., its active state. For a better understanding of\nearth-abundant metal oxides as electrocatalysts for the oxygen evolution\nreaction (OER), the combination of electrochemical (EC) methods and X-ray\nabsorption spectroscopy (XAS) has been very insightful and still holds untapped\npotential. Herein, we concisely introduce the basics of EC and XAS and provide\nthe necessary framework to discuss changes that electrocatalytic materials\nundergo, presenting manganese oxides as examples. Such changes may occur during\npreparation and storage, during immersion in an electrolyte, as well as during\napplication of potentials without or with catalytic reactions. We conclude with\na concise summary of how EC and XAS are currently combined to elucidate the\nactive state as well as an outlook on future opportunities to understand the\nmechanisms of electrocatalysis using combined operando EC-XAS experiments."
    },
    {
        "anchor": "Defect detection in glass fabric reinforced thermoplastics by\n  laboratory-based X-ray scattering: Glass fabric reinforced thermoplastic (GFRT) constitutes a class of composite\nmaterials that are especially suited for automobile construction due to their\ncombination of low weight, ease of production and mechanical properties.\nHowever, in the manufacturing process, during forming of prefabricated\nlaminates, defects in the glass fabric as well as in the polymer matrix can\noccur, which may compromise the safety or the lifetime of components. Thus, the\ndetection of defects in GFRTs for production monitoring and a deep\nunderstanding of defect formation/evolution is essential for mass production.\nHere, we experimentally demonstrate that a certain type of defects (i.e., local\nfiber shifts), can be detected reliably by X-ray scattering based on the\nedge-illumination principle.",
        "positive": "Programmable Control of Nucleation for Algorithmic Self-Assembly: Algorithmic self-assembly, a generalization of crystal growth processes, has\nbeen proposed as a mechanism for autonomous DNA computation and for bottom-up\nfabrication of complex nanostructures. A `program' for growing a desired\nstructure consists of a set of molecular `tiles' designed to have specific\nbinding interactions. A key challenge to making algorithmic self-assembly\npractical is designing tile set programs that make assembly robust to errors\nthat occur during initiation and growth. One method for the controlled\ninitiation of assembly, often seen in biology, is the use of a seed or catalyst\nmolecule that reduces an otherwise large kinetic barrier to nucleation. Here we\nshow how to program algorithmic self-assembly similarly, such that seeded\nassembly proceeds quickly but there is an arbitrarily large kinetic barrier to\nunseeded growth. We demonstrate this technique by introducing a family of tile\nsets for which we rigorously prove that, under the right physical conditions,\nlinearly increasing the size of the tile set exponentially reduces the rate of\nspurious nucleation. Simulations of these `zig-zag' tile sets suggest that\nunder plausible experimental conditions, it is possible to grow large seeded\ncrystals in just a few hours such that less than 1 percent of crystals are\nspuriously nucleated. Simulation results also suggest that zig-zag tile sets\ncould be used for detection of single DNA strands. Together with prior work\nshowing that tile sets can be made robust to errors during properly initiated\ngrowth, this work demonstrates that growth of objects via algorithmic\nself-assembly can proceed both efficiently and with an arbitrarily low error\nrate, even in a model where local growth rules are probabilistic."
    },
    {
        "anchor": "Tuning independently Fermi energy and spin splitting in Rashba systems:\n  Ternary surface alloys on Ag(111): By detailed first-principles calculations we show that the Fermi energy and\nthe Rashba splitting in disordered ternary surface alloys (BiPbSb)/Ag(111) can\nbe independently tuned by choosing the concentrations of Bi and Pb. The\nfindings are explained by three fundamental mechanisms, namely the relaxation\nof the adatoms, the strength of the atomic spin-orbit coupling, and band\nfilling. By mapping the Rashba characteristics,i.e.the splitting and the Rashba\nenergy, and the Fermi energy of the surface states in the complete range of\nconcentrations. Our results suggest to investigate experimentally effects which\nrely on the Rashba spin-orbit coupling in dependence on spin-orbit splitting\nand band filling.",
        "positive": "Valence band electronic structure evolution of graphene oxide upon\n  thermal annealing for optoelectronics: We report valence band electronic structure evolution of graphene oxide (GO)\nupon its thermal reduction. Degree of oxygen functionalization was controlled\nby annealing temperatures, and an electronic structure evolution was monitored\nusing real-time ultraviolet photoelectron spectroscopy. We observed a drastic\nincrease in density of states around the Fermi level upon thermal annealing at\n~600 oC. The result indicates that while there is an apparent band gap for GO\nprior to a thermal reduction, the gap closes after an annealing around that\ntemperature. This trend of band gap closure was correlated with electrical,\nchemical, and structural properties to determine a set of GO material\nproperties that is optimal for optoelectronics. The results revealed that\nannealing at a temperature of ~500 oC leads to the desired properties,\ndemonstrated by a uniform and an order of magnitude enhanced photocurrent map\nof an individual GO sheet compared to as-synthesized counterpart."
    },
    {
        "anchor": "Origin of lowered magnetic moments in epitaxially strained thin films of\n  multiferroic Bi$_2$FeCrO$_6$: We have investigated the effect of epitaxial strain on the magnetic\nproperties and $B$-site cation ordering in multiferroic Bi$_2$FeCrO$_6$ (001)\nthin films using a density-functional theory approach. We find that in thin\nfilms with rock-salt ordering of Fe and Cr the ground state is characterised by\nC-type anti-ferromagnetic (AFM) order. This is in contrast to the bulk form of\nthe material which was predicted to be a ferrimagnet with G-type AFM order.\nFurthermore, the cation ordered thin-films undergo a transition with epitaxial\nstrain from C to A-type AFM order. Other magnetic orders appear as thermally\naccessible excited states. We also find that $B$-site cation disordered\nstructures are more stable in coherent epitaxial strains thereby explaining the\nlowered magnetic moments observed in these samples at room temperature. Strain\nvaries both the sign as well as strength of the Fe-Cr superexchange coupling\nresulting in a very interesting phase diagram for Bi$_2$FeCrO$_6$ thin films.",
        "positive": "Structural/microstructural, optical and electrical investigations of\n  Sb-SnO2 thin films deposited by spray pyrolysis: The structural, optical and electrical properties of spray deposited antimony\n(Sb) doped tin oxide (SnO2) thin films, prepared from SnCl4 precursor, have\nbeen studied as a function of antimony doping concentration. The doping\nconcentration was varied from 0 to 1.5 wt.% of Sb. The analysis of x-ray\ndiffraction patterns revealed that the as deposited doped and undoped tin oxide\nthin films are pure crystalline tetragonal rutile phase of tin oxide which\nbelongs to the space group P42/mnm (number 136). The surface morphological\nexamination with field emission scanning electron microscopy (FESEM) revealed\nthe fact that the grains are closely packed and pores/voids between the grains\nare very few. The transmittance spectra for as-deposited films were recorded in\nthe wavelength range of 200 to 1000 nm. The transmittance of the films was\nobserved to increase from 57% to 68% (at 800 nm) on initial addition of Sb (up\nto [Sb]/[Sn] = 0.5 wt.%) and then it is decreased for higher level of antimony\ndoping ([Sb]/[Sn] > 0.5 wt.%). The sheet resistance of tin oxide films was\nfound to decrease from 48 \\Omega/sq for undoped films to 8 \\Omega/sq for\nantimony doped films."
    },
    {
        "anchor": "Crystal growth in confinement: The growth of crystals confined in porous or cellular materials is ubiquitous\nin Nature and industry. Confinement affects the formation of biominerals in\nliving organisms, of minerals in the Earth's crust and of salt crystals\ndamaging porous limestone monuments, and is also used to control the growth of\nartificial crystals. However, the mechanisms by which confinement alters\ncrystal shapes and growth rates are still not elucidated. Based on novel\n\\textit{in situ} optical observations of (001) surfaces of NaClO$_3$ and\nCaCO$_3$ crystals at nanometric distances from a glass substrate, we\ndemonstrate that new molecular layers can nucleate homogeneously and propagate\nwithout interruption even when in contact with other solids, raising the\nmacroscopic crystal above them. Confined growth is governed by the peculiar\ndynamics of these molecular layers controlled by the two-dimensional transport\nof mass through the liquid film from the edges to the center of the contact,\nwith distinctive features such as skewed dislocation spirals, kinetic\nlocalization of nucleation in the vicinity of the contact edge, and directed\ninstabilities. Confined growth morphologies can be predicted from the values of\nthree main dimensionless parameters.",
        "positive": "Quantum simulations of charge-separation at a model donor-acceptor\n  interface: role of delocalization and local packing: We investigate the electronic dynamics of a model organic photovoltaic (OPV)\nsystem consisting of polyphenylene vinylene (PPV) oligomers and a [6,6]-phenyl\nC61-butyric acid methylester (PCBM) blend using a mixed molecular\nmechanics/quantum mechanics (MM/QM) approach. Using a heuristic model that\nconnects energy gap fluctuations to the average electronic couplings and\ndecoherence times, we provide and estimate of the state-to-state internal\nconversion rates within the manifold of the lowest few electronic excitations.\nWe show that the electronic dynamics of the OPV are dramatically altered by\nvarying the positions of the molecules simulated at the interface. The lowest\nfew excited states of the model interface rapidly mix allowing low frequency\nC-C out of plain torsions to modulate the potential energy surface such that\nthe system can sample both intermolecular charge-transfer and charge-separated\nelectronic configurations on sub 100 fs time scales. Our simulations support an\nemerging picture of carrier generation in OPV systems in which interfacial\nelectronic states can rapidly decay into charge-separated and current producing\nstates via coupling to vibronic degrees of freedom."
    },
    {
        "anchor": "Antiferromagnetic real-space configuration probed by dichroism in\n  scattered x-ray beams with orbital angular momentum: X-ray beams with orbital angular momentum (OAM) are a promising tool for\nx-ray characterization techniques. Beams with OAM have a helicity--an\nazimuthally varying phase--which leads to a gradient of the light field. New\nmaterial properties can be probed by utilizing the helicity of an OAM beam.\nHere, we demonstrate a novel dichroic effect in resonant diffraction from an\nartificial antiferromagnet with a topological defect. We found that the\nscattered OAM beam has circular dichroism at the antiferromagnetic Bragg peak\nwhose sign is coupled to its helicity, which reveals the real-space\nconfiguration of the antiferromagnetic ground state. Thermal cycling of the\nartificial antiferromagnet can change the ground state, as indicated by\nreversal of the sign of circular dichroism. This result is one of the first\ndemonstrations of a soft x-ray spectroscopy characterization technique\nutilizing the OAM of x-rays. This helicity-dependent circular dichroism\nexemplifies the potential to utilize OAM beams to probe matter in a way that is\ninaccessible using currently available x-ray techniques.",
        "positive": "Kinetic Analysis of Illite Dehydroxylation Based on Differential\n  Scanning Calorimetry: The two-step dehydroxylation of illite is studied using the differential\nscanning calorimetry on powder samples with heating rates from 1 to 10\n${\\deg}$C min$^{-1}$ in a dynamic argon atmosphere. The values of apparent\nactivation energy and pre-exponential factor are calculated using the Kissinger\nmethod. The determined values of apparent activation energy and pre-exponential\nfactor of trans-vacant layer dehydroxylation are $(227 \\pm 6)$ kJ mol$^{-1}$\nand $(2.87 \\pm 0.09) \\times 10^{13}$ min$^{-1}$, respectively. The results also\nshow that this process can be characterized by 1D diffusion controlled reaction\nwith instantaneous nucleation rate. For the cis-vacant layer dehydroxylation,\nthe values of apparent activation energy and pre-exponential factor are $(242\n\\pm 10)$ kJ mol$^{-1}$ and $(5.37 \\pm 0.23) \\times 10^{12}$ min$^{-1}$,\nrespectively. The value of Avrami peak factor for this step indicates diffusion\ncontrolled growth of the new phase with zero or decreasing nucleation rate."
    },
    {
        "anchor": "High Thermoelectric Powerfactor in Single and Few-Layer MoS$_2$: The quest for high-efficiency heat-to-electricity conversion has been one of\nthe major driving forces towards renewable energy production for the future.\nEfficient thermoelectric devices require high voltage generation from a\ntemperature gradient and a large electrical conductivity, while maintaining a\nlow thermal conductivity. For a given thermal conductivity and temperature, the\nthermoelectric powerfactor is determined by the electronic structure of the\nmaterial. Low dimensionality (1D and 2D) opens new routes to high powerfactor\ndue to the unique density of states (DOS) of confined electrons and holes. 2D\ntransition metal dichalcogenide (TMDC) semiconductors represent a new class of\nthermoelectric materials not only due to such confinement effects, but\nespecially due to their large effective masses and valley degeneracies. Here we\nreport a powerfactor of $MoS_2$ as large as $8.5 mWm^{-1}K^{-2}$ at room\ntemperature, which is amongst the highest measured in traditional, gapped\nthermoelectric materials. To obtain these high powerfactors, we perform\nthermoelectric measurements on few-layer $MoS_2$ in the metallic regime, which\nallows us to access the 2D DOS near the conduction band edge and exploit the\neffect of 2D confinement on electron scattering rates, which result in a large\nSeebeck coefficient. The demonstrated high, electronically modulated\npowerfactor in 2D TMDCs holds promise for efficient thermoelectric energy\nconversion.",
        "positive": "Direct evidence of ferromagnetism in a quantum anomalous Hall system: Quantum anomalous Hall (QAH) systems are of great fundamental interest and\npotential application because of their dissipationless conduction without the\nneed for external magnetic field. The QAH effect has been realized in\nmagnetically doped topological insulator thin films. However, full quantization\nrequires extremely low temperature ($T< 50\\,$mK) in the initial works, though\nit has been significantly improved with modulation doping or co-doping of\nmagnetic elements. Improved ferromagnetism has been shown in these thin films,\nyet direct evidence of long-range ferromagnetic order is lacking. Herein, we\npresent direct visualization of long-range ferromagnetic order in thin films of\nCr and V co-doped (Bi,Sb)$_2$Te$_3$ using low-temperature magnetic force\nmicroscopy with $\\textit{in-situ}$ transport. The magnetization reversal\nprocess reveals typical ferromagnetic domain behavior, i.e., domain nucleation\nand possibly domain wall propagation, in contrast to much weaker magnetic\nsignals observed in the end members, possibly due to superparamagnetic\nbehavior. The observed long-range ferromagnetic order resolves one of the major\nchallenges in QAH systems, and paves the way to high-temperature\ndissipationless conduction by exploring magnetic topological insulators."
    },
    {
        "anchor": "Tailoring of Grain Boundary Structure and Chemistry of Cathode Particles\n  for Enhanced Cycle Stability of Lithium Ion Battery: The biggest challenge for the commercialization of layered structured nickel\nrich lithium transition metal oxide cathode is the capacity and voltage fading.\nResolving this problem over the years follows an incremental progress. In this\nwork, we report our finding of totally a new approach to revolutionize the\ncycle stability of aggregated cathode particles for lithium ion battery at both\nroom and elevated temperatures. We discover that infusion of a solid\nelectrolyte into the grain boundaries of the cathode secondary particles can\ndramatically enhance the capacity retention and voltage stability of the\nbattery. We find that the solid electrolyte infused in the boundaries not only\nacts as a fast channel for Li ion transport, but also most importantly prevents\npenetration of the liquid electrolyte into the boundaries, consequently\neliminating the detrimental factors that include solid-liquid interfacial\nreaction, intergranular cracking, and layer to spinel phase transformation. The\npresent work, for the first time, reveals unprecedented insight as how the\ncathode behaves in the case of not contacting with the liquid electrolyte,\nultimately points toward a general new route, via grain boundary engineering,\nfor designing of better batteries of both solid-liquid and solid state systems.",
        "positive": "Preparation and analysis of strain-free uranium surfaces for electron\n  and x-ray diffraction analysis: This work describes a methodology for producing high quality metallic\nsurfaces from uranium primarily for characterisation and investigations\ninvolving electron backscatter diffraction. Electrochemical measurements have\nbeen conducted to inform ideal polishing conditions to produce surfaces free\nfrom strain, induced by mechanical polishing. A commonly used solution for the\nelectropolishing of uranium, consisting in part of phosphoric acid, was used to\nconduct the electrochemical experiments and polishing. X-ray diffraction\ntechniques focusing on the surface show low stresses and strains are exhibited\nwithin the material. This is mirrored in good quality electron backscatter\ndiffraction."
    },
    {
        "anchor": "Sub-nanoscale Temperature, Magnetic Field and Pressure sensing with Spin\n  Centers in 2D hexagonal Boron Nitride: Spin defects in solid-state materials are strong candidate systems for\nquantum information technology and sensing applications. Here we explore in\ndetails the recently discovered negatively charged boron vacancies ($V_B^-$) in\nhexagonal boron nitride (hBN) and demonstrate their use as atomic scale sensors\nfor temperature, magnetic fields and externally applied pressure. These\napplications are possible due to the high-spin triplet ground state and bright\nspin-dependent photoluminescence (PL) of the $V_B^-$. Specifically, we find\nthat the frequency shift in optically detected magnetic resonance (ODMR)\nmeasurements is not only sensitive to static magnetic fields, but also to\ntemperature and pressure changes which we relate to crystal lattice parameters.\nOur work is important for the future use of spin-rich hBN layers as intrinsic\nsensors in heterostructures of functionalized 2D materials.",
        "positive": "Formation of hyperfine fields in alloys: This work deals with the analysis of experimental data on the average\nmagnetization of $Fe_{1-x}Me_x$ (Me=Sn,Si) disordered alloys, the average and\nlocal hyperfine fields (HFF) at the Fe nuclei. The effect of the metalloid\nconcentration on the HFF is studied with the help of the results of first-\nprinciples calculations of ordered alloys. The disorder is taken into account\nby means of model systems. The dependences obtained correspond to those\nexperimentally observed. Experimental data on the ratio of the average HFF at\nFe nuclei to the average magnetisation in alloys with sp-elements show that the\nratio decreases proportionally with the metalloid concentration. This change in\nthe ratio is bound up with three factors. First, the contribution of the\nvalence electron polarization by the neighboring atoms, that is positive\n(unlike the polarization by the own magnetic moment), increases with the change\nof the disorder degree (increase of concentration). Second, the appearance of\nthe impurities, i.e. metalloid atoms, in the nearest environment of Fe leads to\nthe orbital moment increase. And, finally, the change of the disorder degree,\nas in the first case, results in an increase in the orbital magnetic moment and\nits positive contribution to the HFF. The value and the degree of the influence\nof these contributions to the HFF is discussed."
    },
    {
        "anchor": "Prediction of a supersolid phase in high-pressure deuterium: Supersolid is a mysterious and puzzling state of matter whose possible\nexistence has stirred a vigorous debate among physicists for over 60 years. Its\nelusive nature stems from the coexistence of two seemingly contradicting\nproperties, long-range order and superfluidity. We report computational\nevidence of a supersolid phase of deuterium under high pressure ($p >800$ GPa)\nand low temperature (T $<$ 1.0 K). In our simulations, that are based on\nbosonic path integral molecular dynamics, we observe a highly concerted\nexchange of atoms while the system preserves its crystalline order. The\nexchange processes are favoured by the soft core interactions between deuterium\natoms that form a densely packed metallic solid. At the zero temperature limit,\nBose-Einstein condensation is observed as the permutation probability of $N$\ndeuterium atoms approaches $1/N$ with a finite superfluid fraction. Our study\nprovides concrete evidence for the existence of a supersolid phase in\nhigh-pressure deuterium and could provide insights on the future investigation\nof supersolid phases in real materials.",
        "positive": "Coarse-Grained Molecular Dynamics Modeling of A Branched Polyetherimide: A coarse-grained model is developed to allow large-scale molecular dynamics\n(MD) simulations of a branched polyetherimide derived from two backbone\nmonomers [4,4'-bisphenol A dianhydride (BPADA) and m-phenylenediamine (MPD)], a\nchain terminator [phthalic anhydride (PA)], and a branching agent\n[tris[4-(4-aminophenoxy)phenyl] ethane (TAPE)]. An atomistic model is first\nbuilt for the branched polyetherimide. A systematic protocol based on\nchemistry-informed grouping of atoms, derivation of bond and angle interactions\nby direct Boltzmann inversion, and parameterization of nonbonded interactions\nby potential of mean force (PMF) calculations via gas-phase MD simulations of\natomic group pairs, is used to construct the coarse-grained model. A six-pair\ngeometry, with one atomic group at the center and six replicates of the other\natomic group placed surrounding the central group in a NaCl structure, has been\ndemonstrated to significantly speed up the PMF calculations and partially\ncapture the many-body aspect of the PMFs. Furthermore, we propose a correction\nterm to the PMFs that can make the resulting coarse-grained model transferable\ntemperature-wise, by enabling the model to capture the thermal expansion\nproperty of the polymer. The coarse-grained model has been applied to explore\nthe mechanical, structural, and rheological properties of the branched\npolyetherimide."
    },
    {
        "anchor": "Negative tunneling magnetoresistance by canted magnetization in MgO/NiO\n  tunnel barriers: The influence of insertion of an ultra-thin NiO layer between the MgO barrier\nand ferromagnetic electrode in magnetic tunnel junctions has been investigated\nby measuring the tunneling magnetoresistance and the X-ray magnetic circular\ndichroism (XMCD). The magnetoresistance shows a high asymmetry with respect to\nbias voltage, giving rise to a negative value of -16% at 2.8 K. We attribute\nthis to the formation of non-collinear spin structures in the NiO layer as\nobserved by XMCD. The magnetic moments of the interface Ni atoms tilt from the\neasy axis due to exchange interaction and the tilting angle decreases with\nincreasing the NiO thickness. The experimental observations are further support\nby non-collinear spin density functional theory.",
        "positive": "Intrinsically patterned two-dimensional transition metal halides: Patterning and defect engineering are key methods to tune 2D materials'\nproperties. However, generating 2D periodic patterns of point defects in 2D\nmaterials has been elusive until now, despite the well-established methods for\ncreating isolated point defects and defect lines. Herein, we report on\nintrinsically patterned 2D transition metal dihalides on metal surfaces\nfeaturing periodic halogen vacancies that result in alternating coordination of\nthe transition metal atoms throughout the film. Using low-temperature scanning\nprobe microscopy and low-energy electron diffraction, we identified the\nstructural properties of patterned FeBr$_2$ and CoBr$_2$ monolayers grown\nepitaxially on Au(111). Density-functional theory reveals that the Br-vacancies\nare facilitated by low formation energies and accompanied by a lateral\nsoftening of the layers leading to a significant reduction of the lattice\nmismatch to the underlying Au(111). We demonstrate that interfacial epitaxial\nstrain engineering presents a versatile strategy for controlled patterning in\n2D. In particular, patterning 2D magnets provides new pathways to create\nunconventional spin textures with non-collinear spin."
    },
    {
        "anchor": "The Renaissance of Black Phosphorus: One hundred years after its first successful synthesis in the bulk form in\n1914, black phosphorus (black P) was recently rediscovered from the perspective\nof a two-dimensional (2D) layered material, attracting tremendous interest from\ncondensed matter physicists, chemists, semiconductor device engineers and\nmaterial scientists. Similar to graphite and transition metal dichalcogenides\n(TMDs), black P has a layered structure but with a unique puckered single layer\ngeometry. Because the direct electronic band gap of thin film black P can be\nvaried from 0.3 to around 2 eV, depending on its film thickness, and because of\nits high carrier mobility and anisotropic in-plane properties, black P is\npromising for novel applications in nanoelectronics and nanophotonics different\nfrom graphene and TMDs. Black P as a nanomaterial has already attracted much\nattention from researchers within the past year. Here, we offer our opinions on\nthis emerging material with the goal of motivating and inspiring fellow\nresearchers in the 2D materials community and the broad readership of PNAS to\ndiscuss and contribute to this exciting new field. We also give our\nperspectives on future 2D and thin film black P research directions, aiming to\nassist researchers coming from a variety of disciplines who are desirous of\nworking in this exciting research field.",
        "positive": "Observed Effects of a Changing Step-Edge Density on Thin-Film Growth\n  Dynamics: We grew SrTiO3 on SrTiO3 [001] by pulsed laser deposition, while observing\nx-ray diffraction at the (0 0 .5) position. The drop dI in the x-ray intensity\nfollowing a laser pulse contains information about plume-surface interactions.\nKinematic theory predicts dI/I = -4sigma(1-sigma), so that dI/I depends only on\nthe amount of deposited material sigma. In contrast, we observed experimentally\nthat |dI/I| < 4sigma(1-sigma), and that dI/I depends on the phase of x-ray\ngrowth oscillations. The combined results suggest a fast smoothing mechanism\nthat depends on surface step-edge density."
    },
    {
        "anchor": "Diffusion of hydrogen atoms in silicon layers deposited from molecular\n  beams on dielectric substrates: In the paper, the processes occurring during low-temperature growth of\nnon-hydrogenated amorphous Si and polycrystalline Si films on multilayer\nSi$_3$N$_4$/SiO$_2$/c-Si substrates from molecular beams under conditions of\nultrahigh vacuum are studied in detail. Diffusion of hydrogen atoms from a\ndielectric layer into the growing film is shown to accompany the growth of a\nsilicon film on a Si$_3$N$_4$ layer deposited by CVD or on a SiO$_2$ layer\nobtained by thermal oxidation of a silicon wafer. The process of hydrogen\nmigration from the dielectric substrates into the silicon film is studied using\nFTIR spectroscopy. The reduction of IR absorption at the bands related to the\nN$-$H bonds vibrations and the increase of IR absorption at the bands relating\nto the Si$-$N bonds vibrations in IR spectra demonstrate that hydrogen atoms\nleave Si$_3$N$_4$ layer during Si deposition from a molecular beam. The\nabsorption band assigned to the valence vibrations of the Si$-$H bond at $\\sim\n2100$ cm$^{-1}$ emerging in IR spectra obtained at samples deposited both on\nSi$_3$N$_4$ and SiO$_2$ layers indicates the accumulation of hydrogen atoms in\nsilicon films. The difference in chemical potentials of hydrogen atoms in the\ndielectric layer and the silicon film explains the transfer of hydrogen atoms\nfrom the Si$_3$N$_4$ or SiO$_2$ layer into the growing silicon film.",
        "positive": "Ultra-high pressure disordered eight-coordinated phase of Mg$_2$GeO$_4$:\n  Analogue for super-Earth mantles: Mg2GeO4 is an analogue for the ultra-high pressure behavior of Mg2SiO4, so we\nhave investigated magnesium germanate to 275 GPa and over 2000 K using a\nlaser-heated diamond anvil cell combined with in situ synchrotron X-ray\ndiffraction and density functional theory (DFT) computations. The experimental\nresults are consistent with a novel phase with disordered Mg and Ge, in which\ngermanium adopts eight-fold coordination with oxygen: the cubic Th3P4- type\nstructure. Simulations using the special quasirandom structure (SQS) method\nsuggest partial order in the tetragonal I-42d structure, indistinguishable from\nI-43d Th3P4 in our experiments. These structures have not been reported before\nin any oxide. If applicable to silicates, the formation of this highly\ncoordinated and intrinsically disordered phase would have important\nimplications for the interior mineralogy of large, rocky extrasolar planets."
    },
    {
        "anchor": "Constitutive modelling of mechanically induced martensitic\n  transformations: Prediction of transformation surfaces: Purpose: The purpose of this work is to apply a recently proposed\nconstitutive model for mechanically induced martensitic transformations to the\nprediction of transformation loci. Additionally, this study aims to elucidate\nif a stress-assisted criterion can account for transformations in the so-called\nstrain-induced regime.\n  Design/methodology/approach: The model is derived by generalising the\nstress-based criterion of Patel and Cohen (1953), relying on lattice\ninformation obtained using the Phenomenological Theory of Martensite\nCrystallography. Transformation multipliers (cf. plastic multipliers) are\nintroduced, from which the martensite volume fraction evolution ensues. The\nassociated transformation functions provide a variant selection mechanism.\nAustenite plasticity follows a classical single crystal formulation, to account\nfor transformations in the strain-induced regime. The resulting model is\nincorporated into a fully-implicit RVE-based computational homogenisation\nfinite element code.\n  Findings: Results show good agreement with experimental data for a\nmeta-stable austenitic stainless steel. In particular, the transformation locus\nis well reproduced, even in a material with considerable slip plasticity at the\nmartensite onset, corroborating the hypothesis that an energy-based criterion\ncan account for transformations in both stress-assisted and strain-induced\nregimes.\n  Originality/value: A recently developed constitutive model for mechanically\ninduced martensitic transformations is further assessed and validated. Its\nformulation is fundamentally based on a physical metallurgical mechanism and\nderived in a thermodynamically consistent way, inheriting a consistent\nmechanical dissipation. This model draws on a reduced number of\nphenomenological elements and is a step towards the fully predictive modelling\nof materials that exhibit such phenomena.",
        "positive": "Room Temperature Thermoelectric Properties of Isostructural Selenides\n  Ta2PdS6 and Ta2PdSe6: We have measured thermoelectric properties of Ta2PdX6 (X=S, Se) around room\ntemperature using single crystal samples. We find that the power factor of\nTa2PdX6 is relatively high from middle-low to room temperatures, and notably\nTa2PdSe6 shows the largest power factor among thermoelectric materials with an\nelectrical conductivity of 10-2 {\\Omega}cm at 300 K. Ta2PdS6 will be a possible\ncandidate for a Peltier cooling material if the lattice thermal conductivity is\nreduced by chemical substitution."
    },
    {
        "anchor": "The structure of planar defects in tilted perovskites: A mathematical framework is developed to describe tilted perovskites using a\ntensor description of octahedral deformations. The continuity of octahedral\ntilts through the crystal is described using an operator which relates the\ndeformations of adjacent octahedra; examination of the properties of this\noperator upon application of symmetry elements allows the space group of tilted\nperovskites to be obtained. It is shown that the condition of octahedral\ncontinuity across a planar defect such as an anti-phase boundary or domain wall\nnecessarily leads to different octahedral tilting at the defect, and a method\nis given to predict the local tilt system which will occur in any given case.\nPlanar boundaries in the rhombohedral R3c a-a-a- tilt system are considered as\nan example.",
        "positive": "Structural phase transformation and phase boundary/stability studies of\n  field-cooled Pb(Mg1/3Nb2/3O3)-32%PbTiO3 crystals: Structural phase transformations in (001)-oriented\n(1-x)Pb(Mg1/3Nb2/3O3)-32%PbTiO3 (PMN-x%PT) crystals have been investigated by\nx-ray diffraction. A C->T->MC sequence was observed in both the field-cooled\n(FC) and zero-field-cooled (ZFC) conditions. Most interestingly, an anomalous\nincrease in the C->T phase boundary with increasing field has been observed,\nwhich is seemingly a common characteristic of crystals whose compositions are\nin the vicinity of the MPB, irrespective of the width of the T and MC phase\nregions."
    },
    {
        "anchor": "Time-dependent natural orbitals and occupation numbers: We report equations of motion for the occupation numbers of natural spin\norbitals and show that adiabatic extensions of common functionals employed in\nground-state reduced-density-matrix-functional theory have the shortcoming of\nleading always to occupation numbers which are independent of time. We\nillustrate the exact time-dependence of the natural spin orbitals and\noccupation numbers for the case of electron-ion scattering and for atoms in\nstrong laser fields. In the latter case, we observe strong variations of the\noccupation numbers in time.",
        "positive": "Close-circuit domain quadruplets in BaTiO$_3$ nanorods embedded in\n  SrTiO$_3$ film: Cylindrical BaTiO3 nanorods embedded in (100)-oriented SrTiO3 epitaxial film\nin a brush-like configuration are investigated in the framework of the\nGinzburg-Landau-Devonshire model. It is shown that strain compatibility at\nBaTiO3/SrTiO3 interfaces keeps BaTiO3 nanorods in the rhombohedral phase even\nat room temperature. Depolarization field at the BaTiO3/SrTiO3 interfaces is\nreduced by an emission of the 109-degree or 71-degree domain boundaries. In\ncase of nanorods of about 10-80 nm diameter, the ferroelectric domains are\nfound to form a quadruplet with a robust flux-closure arrangement of the\nin-plane components of the spontaneous polarization. The out-of-plane\ncomponents of the polarization are either balanced or oriented up or down along\nthe nanorod axis. Switching of the out-of-plane polarization with coercive\nfield of about $5.10^6$ V/m occurs as a collapse of a 71-degree cylindrical\ndomain boundary formed at the curved circumference surface of the nanorod. The\nremnant domain quadruplet configuration is chiral, with the $C_4$ macroscopic\nsymmetry. More complex stable domain configurations with coexisting clockwise\nand anticlockwise quadruplets contain interesting arrangement of strongly\ncurved 71-degree boundaries."
    },
    {
        "anchor": "Zeeman interaction and Jahn-Teller effect in $\u0393_8$ multiplet: We present a thorough analysis of the interplay of magnetic moment and the\nJahn-Teller effect in the $\\Gamma_8$ cubic multiplet. We find that in the\npresence of dynamical Jahn-Teller effect, the Zeeman interaction remains\nisotropic, whereas the $g$ and $G$ factors can change their signs. The static\nJahn-Teller distortion also can change the sign of these $g$ factors as well as\nthe nature of the magnetic anisotropy. Combining the theory with\nstate-of-the-art {\\it ab initio} calculations, we analyzed the magnetic\nproperties of Np$^{4+}$ and Ir$^{4+}$ impurity ions in cubic environment. The\ncalculated $g$ factors of Np$^{4+}$ impurity agree well with experimental data.\nThe {\\it ab initio} calculation predicts strong Jahn-Teller effect in Ir$^{4+}$\nion in cubic environment and the strong vibronic reduction of $g$ and $G$\nfactors.",
        "positive": "Anisotropic effects in two-dimensional materials: Among a huge variety of known two-dimensional materials, some of them have\nanisotropic crystal structures; examples include so different systems as a\nfew-layer black phoshphorus (phosphorene), beryllium nitride BeN$_4$, van der\nWaals magnet CrSBr, rhenium dichalgogenides ReX$_2$. As a consequence, their\noptical and electronic properties turn out to be highly anisotropic as well. In\nsome cases, the anisotropy results not just in a smooth renormalization of\nobservable properties in comparison with the isotropic case but in the\nappearance of dramatically new physics. The examples are hyperbolic plasmons\nand excitons, strongly anisotropic ordering of adatoms at the surface of\ntwo-dimensional or van der Waals materials, essential change of transport and\nsuperconducting properties. Here, we present a systematic review of electronic\nstructure, transport and optical properties of several representative groups of\nanisotropic two-dimensional materials including semiconductors, anisotropic\nDirac and semi-Dirac materials, as well as superconductors."
    },
    {
        "anchor": "Electronic structure of the strongly hybridized ferromagnet CeFe2: We report on results from high-energy spectroscopic measurements on CeFe2, a\nsystem of particular interest due to its anomalous ferromagnetism with an\nunusually low Curie temperature and small magnetization compared to the other\nrare earth-iron Laves phase compounds. Our experimental results indicate very\nstrong hybridization of the Ce 4f states with the delocalized band states,\nmainly the Fe 3d states. In the interpretation and analysis of our measured\nspectra, we have made use of two different theoretical approaches: The first\none is based on the Anderson impurity model, with surface contributions\nexplicitly taken into account. The second method consists of band-structure\ncalculations for bulk CeFe2. The analysis based on the Anderson impurity model\ngives calculated spectra in good agreement with the whole range of measured\nspectra, and reveals that the Ce 4f -- Fe 3d hybridization is considerably\nreduced at the surface, resulting in even stronger hybridization in the bulk\nthan previously thought. The band-structure calculations are ab initio\nfull-potential linear muffin-tin orbital calculations within the\nlocal-spin-density approximation of the density functional. The Ce 4f electrons\nwere treated as itinerant band electrons. Interestingly, the Ce 4f partial\ndensity of states obtained from the band-structure calculations also agree well\nwith the experimental spectra concerning both the 4f peak position and the 4f\nbandwidth, if the surface effects are properly taken into account. In addition,\nresults, notably the partial spin magnetic moments, from the band-structure\ncalculations are discussed in some detail and compared to experimental findings\nand earlier calculations.",
        "positive": "A New Class of Boron Nanotube: The configurations, stability and electronic structures of a new class of\nboron sheet and related boron nanotubes are predicted within the framework of\ndensity functional theory. This boron sheet is sparser than those of recent\nproposals. Our theoretic results show that the stable boron sheet remains flat\nand is metallic. There are bands similar to the p-bands in graphite near the\nFermi level. Stable nanotubes with various diameters and chiral vectors can be\nrolled from the sheet. Within our study, only the thin (8, 0) nanotube with a\nband gap of 0.44 eV is semiconducting, while all the other thicker boron\nnanotubes are metallic, independent of their chirality. It indicates the\npossibility, in the design of nanodevices, to control the electronic transport\nproperties of the boron nanotube through the diameter."
    },
    {
        "anchor": "Efficient Electrical Spin Injection from a Magnetic Metal / Tunnel\n  Barrier Contact into a Semiconductor: We report electrical spin injection from a ferromagnetic metal contact into a\nsemiconductor light emitting diode structure with an injection efficiency of\n30% which persists to room temperature. The Schottky barrier formed at the\nFe/AlGaAs interface provides a natural tunnel barrier for injection of spin\npolarized electrons under reverse bias. These carriers radiatively recombine,\nemitting circularly polarized light, and the quantum selection rules relating\nthe optical and carrier spin polarizations provide a quantitative,\nmodel-independent measure of injection efficiency. This demonstrates that spin\ninjecting contacts can be formed using a widely employed contact methodology,\nproviding a ready pathway for the integration of spin transport into\nsemiconductor processing technology.",
        "positive": "Bond relaxation, electronic and magnetic behavior of 2D metals\n  structures Y on Li(110) surface: We investigated the bond, electronic and magnetic behavior of adsorption\nYttrium atoms on Lithium (110) surface using a combination of\nBond-order-length-strength(BOLS) correlation and density-functional\ntheory(DFT). We found that adsorption Y atoms on Li(110) surfaces form\ntwo-dimensional (2D) geometric structures of hexagon, nonagon, solid hexagonal,\nquadrangle and triangle. The consistent with the magnetic moment are\n6.66{\\mu}B, 5.54{\\mu}B, 0.28{\\mu}B, 1.04{\\mu}B, 2.81{\\mu}B, respectively. In\naddition, this work could pave the way for design new 2D metals electronic and\nmagnetic properties."
    },
    {
        "anchor": "Ginzburg-Landau theory of the bcc-liquid interface kinetic coefficient: We extend the Ginzburg-Landau (GL) theory of atomically rough bcc-liquid\ninterfaces [Wu {\\it et al.}, Phys. Rev. B \\textbf{73}, 094101 (2006)] outside\nof equilibrium. We use this extension to derive an analytical expression for\nthe kinetic coefficient, which is the proportionality constant $\\mu(\\hat n)$\nbetween the interface velocity along a direction $\\hat n$ normal to the\ninterface and the interface undercooling. The kinetic coefficient is expressed\nas a spatial integral along the normal direction of a sum of gradient square\nterms corresponding to different nonlinear density wave profiles. Anisotropy\narises naturally from the dependence of those profiles on the angles between\nthe principal reciprocal lattice vectors $\\vec K_i$ and $\\hat n$. Values of the\nkinetic coefficient for the$(100)$, $(110)$ and $(111)$ interfaces are compared\nquantitatively to the prediction of linear Mikheev-Chernov (MC) theory [J.\nCryst. Growth \\textbf{112}, 591 (1991)] and previous molecular dynamics (MD)\nsimulation studies of crystallization kinetics for a classical model of Fe.\nAdditional MD simulations are carried out here to compute the relaxation time\nof density waves in the liquid in order to make this comparison free of fit\nparameter. The GL theory predicts a similar expression for $\\mu$ as the MC\ntheory but yields a better agreement with MD simulations for both its magnitude\nand anisotropy due to a fully nonlinear description of density wave profiles\nacross the solid-liquid interface. GL theory is also used to derive an inverse\nrelation between $\\mu$ and the solid-liquid interfacial free-energy. The\ngeneral methodology used here to derive an expression for $\\mu(\\hat n)$ also\napplies to amplitude equations derived from the phase-field-crystal model,\nwhich only differ from GL theory by the choice of cubic and higher order\nnonlinearities in the free-energy density.",
        "positive": "Tuning hole mobility of individual p-doped GaAs nanowires by uniaxial\n  tensile stress: Strain engineering provides an effective way of tailoring the electronic and\noptoelectronic properties of semiconductor nanomaterials and nanodevices,\ngiving rise to novel functionalities. Here, we present direct experimental\nevidence of strain-induced modifications of hole mobility in individual GaAs\nnanowires, using in situ transmission electron microscopy (TEM). The\nconductivity of the nanowires varied with applied uniaxial tensile stress,\nshowing an initial decrease of ~5-20% up to a stress of 1~ 2 GPa, subsequently\nincreasing up to the elastic limit of the nanowires. This is attributed to a\nhole mobility variation due to changes in the valence band structure caused by\nstress and strain. The corresponding lattice strain in the nanowires was\nquantified by in situ 4D-scanning TEM (STEM) and showed a complex spatial\ndistribution at all stress levels. Meanwhile, a significant red shift of the\nband gap induced by the stress and strain was unveiled by monochromated\nelectron energy loss spectroscopy."
    },
    {
        "anchor": "Different shapes of impurity concentration profiles formed by long-range\n  interstitial migration: A model of interstitial impurity migration is proposed which explains the\nredistribution of ion-implanted boron in low-temperature annealing of\nnonamorphized silicon layers. It is supposed that nonequilibrium boron\ninterstitials are generated either in the course of ion implantation or at the\ninitial stage of thermal treatment and that they migrate inward and to the\nsurface of a semiconductor in the basic stage of annealing. It is shown that\nthe form of the \"tail\" in the boron profile with the logarithmic concentration\naxis changes from a straight line if the average lifetime of impurity\ninterstitials is substantially shorter than the annealing duration to that\nbending upwards for increasing lifetime. The calculated impurity concentration\nprofiles are in excellent agreement with the experimental data describing the\nredistribution of implanted boron for low-temperature annealing at 750 Celsius\ndegrees for 1 h and at 800 Celsius degrees for 35 min. Simultaneously, the\nexperimental phenomenon of incomplete electrical activation of boron atoms in\nthe \"tail\" region is naturally explained.",
        "positive": "Non-linear density functional theory: A direct method to calculate\n  many-electron charge densities: We suggest to include the density of electron charge explicitly in the\nelectron potential of density functional theory, rather than implicitly via\nexchange-correlation functionals. The advantages of the approach are conceptual\nand numerical. Conceptually, it allows to formulate a physical principle for\nthe development of quantum mechanical systems: it is the principle of energetic\nequilibrium, because the energy principle, in this case, applies not only\nglobally, but also on a local level. The method is an order-$N$ method, scaling\nlinearly with the number of atoms. It is used to calculate the electronic\ngroundstate of a metallic surface, where we find good agreement with\nexperimental values."
    },
    {
        "anchor": "Visualizing Three-Dimensional Micromechanical Response in Nanomaterials: Understanding mechanical properties of materials requires not only complete\ndetermination of the three-dimensional response at a local scale, but also\nknowledge of the mode or the mechanism by which deformation takes place.\nProbing mechanical response at such a depth can be only achieved through a\ndiffraction based method. In spite of this, diffraction based methods still are\nnot commonly employed for strain measurements because they are perceived as\nvery time intensive and non-intuitive. Herein we introduce the concept of a\ndiffraction strain ellipsoid, and show how its shape, thickness, and\norientation represent the complete deformation state in a powerfully visual and\nintuitive way. We also show how the geometry of the ellipsoid can be very\nquickly determined from x-ray diffraction data obtained using a large area\ndetector, and how it can be used to understand micromechanical deformation of\nnanocrystalline materials.",
        "positive": "Influence of Ti/V Cation-Exchange in Na$_2$Ti$_3$O$_7$ on Na-Ion\n  Negative Electrode Performance: an Insight from First-Principles Study: Sodium-titanate \\ce{Na2Ti3O7} (NTO) is regarded as a highly promising anode\nmaterial with a very low voltage for Na-ion batteries and capacitors, but\nsuffered from relatively low specific capacity and poor electron conductivity.\nHere we report a first-principles study of electrochemical properties of NTO\nand its vanadium-modified compounds, \\ce{Na2Ti2VO7} and \\ce{Na2TiV2O7} (NTVO),\noffering an insight into their detailed working mechanism and an evidence of\nenhancing anode performance by Ti/V cation exchange. Our calculations reveal\nthat the specific capacity can increase from 177 mAh g$^{-1}$ in NTO to over\n280 mAh g$^{-1}$ in NTVO when using \\ce{NaTi_{3-$x$}V_{$x$}O7} ($x$ = 1, 2) as\na starting material for Na insertion due to higher oxidation state of\n\\ce{V^{+5}}, together with lower voltages and small volume expansion rates\nbelow 3\\%. With Ti/V exchange, we obtain slightly higher activation energies\nfor Na ion migrations along the two different pathways, but find an obvious\nimprovement of electronic transport in NTVO."
    },
    {
        "anchor": "First-principles calculations of double resonance Raman spectra for\n  monolayer MoTe$_2$: Since double resonance Raman (DRR) spectra are laser-energy dependent, the\nfirst-principles calculations of DRR for two-dimensional materials are\nchallenging. Here, the DRR spectrum of monolayer MoTe$_2$ is calculated by\nhome-made program, in which we combine {\\em ab-initio}\ndensity-functional-theory calculations with the electron-phonon Wannier (EPW)\nmethod. Within the fourth-order perturbation theory, we are able to quantify\nnot only the electron-photon matrix elements within the dipole approximation,\nbut also the electron-phonon matrix elements using the Wannier functions. The\nreasonable agreement between the calculated and experimental Raman spectra is\nachieved, in which we reproduce some distinctive features of transition metal\ndichalcogenides (TMDCs) from graphene (for example, the dominant intervalley\nprocess involving an electron or a hole). Furthermore, we perform an analysis\nof the possible DRR modes over the Brillouin zone, highlighting the role of\nlow-symmetry points. Raman tensors for some DRR modes are given by first\nprinciples calculations from which laser polarization dependence is obtained.",
        "positive": "High Dielectric Ternary Oxides from Crystal Structure Prediction and\n  High-throughput Screening: The development of new high dielectric materials is essential for advancement\nin modern electronics. Oxides are generally regarded as the most promising\nclass of high dielectric materials for industrial applications as they possess\nboth high dielectric constants and large band gaps. Most previous researches on\nhigh dielectrics were limited to already known materials. In this study, we\nconducted an extensive search for high dielectrics over a set of ternary oxides\nby combining crystal structure prediction and density functional perturbation\ntheory calculations. From this search, we adopted multiple stage screening to\nidentify 440 new low-energy high dielectric materials. Among these materials,\n33 were identified as potential high dielectrics favorable for modern device\napplications. Our research has opened an avenue to explore novel high\ndielectric materials by combining crystal structure prediction and high\nthroughput screening."
    },
    {
        "anchor": "TherMos3, a tool for 3D electrothermal simulation of Smart Power Mosfets: In this paper we report on a novel simulation tool designed for the 3D\ncoupled electro-thermal simulation of Smart Power Mosfets, that is a tool\ncapable of taking into account not only the electrical (and thermal) behaviour\nof the power device but also the different driving strategies as they are\nimposed by a control logic circuit which usually resides on the same chip. The\nsimulator is fully developed under Matlab and solves, self consistently, the 3D\nheat equation with proper boundary conditions and heat sources. An adaptive\nmeshing algorithm based on temperature gradients and an optimized time stepping\nstrategy have also been developed to reduce computational load and speed up\nsimulation time without loosing accuracy. To validate this approach, simulator\nresults are finally compared to experimental data obtained on a commercial\nSmart Power device used in automotive applications.",
        "positive": "Heat capacity and phonon mean free path of wurtzite GaN: We report on lattice specific heat of bulk hexagonal GaN measured by the heat\nflow method in the temperature range 20-300 K and by the adiabatic method in\nthe range 5-70 K. We fit the experimental data using two temperatures model.\nThe best fit with the accuracy of 3 % was obtained for the temperature\nindependent Debye's temperature $\\theta_{\\rm D}=365$ {\\rm K} and Einstein's\ntemperature $\\theta_{\\rm E}=880$ {\\rm K}. We relate these temperatures to the\nfunction of density of states. Using our results for heat conduction\ncoefficient, we established in temperature range 10-100 K the explicit\ndependence of the phonon mean free path on temperature $\\it{l}_{\\rm ph}\\propto\nT^{-2}$. Above 100 K, there is the evidence of contribution of the Umklapp\nprocesses which limit phonon free path at high temepratures. For phonons with\nenergy $k_{\\rm B}\\times 300 $ {\\rm K} the mean free path is of the order 100\n{\\rm nm}"
    },
    {
        "anchor": "Quantum size effect on the dissociation of O2 molecules on ultrathin\n  Pb(111) films: Using first-principles calculations, we systematically study the dissociation\nof O$_2$ molecules on different ultrathin Pb(111) films. Based on our previous\nwork revealing the molecular adsorption precursor states for O$_2$, we further\nexplore that why there are two nearly degenerate adsorption states on Pb(111)\nultrathin films, but no precursor adsorption states exist at all on the\nMg(0001) and Al(111) surfaces. And the reason is concluded to be the different\nsurface electronic structures. For the O$_2$ dissociation, we consider both the\nreaction channels from gas-like and molecularly adsorbed O$_2$ molecules. We\nfind that the energy barrier for O$_2$ dissociation from the molecular\nadsorption precursor states is always smaller than from O$_2$ gases. The most\nenergetically favorable dissociation process is found to be the same on\ndifferent Pb(111) films, and the energy barriers are found to be modulated by\nthe quantum size effects of Pb(111) films.",
        "positive": "Excitonic linewidth approaching the homogeneous limit in MoS2 based van\n  der Waals heterostructures : accessing spin-valley dynamics: The strong light matter interaction and the valley selective optical\nselection rules make monolayer (ML) MoS2 an exciting 2D material for\nfundamental physics and optoelectronics applications. But so far optical\ntransition linewidths even at low temperature are typically as large as a few\ntens of meV and contain homogenous and inhomogeneous contributions. This\nprevented in-depth studies, in contrast to the better-characterized ML\nmaterials MoSe2 and WSe2. In this work we show that encapsulation of ML MoS2 in\nhexagonal boron nitride can efficiently suppress the inhomogeneous contribution\nto the exciton linewidth, as we measure in photoluminescence and reflectivity a\nFWHM down to 2 meV at T = 4K. This indicates that surface protection and\nsubstrate flatness are key ingredients for obtaining stable, high quality\nsamples. Among the new possibilities offered by the well-defined optical\ntransitions we measure the homogeneous broadening induced by the interaction\nwith phonons in temperature dependent experiments. We uncover new information\non spin and valley physics and present the rotation of valley coherence in\napplied magnetic fields perpendicular to the ML."
    },
    {
        "anchor": "Interface-induced field-like optical spin torque in a ferromagnet/heavy\n  metal heterostructure: The manipulation of magnetization in a metallic ferromagnet by using optical\nhelicity has been much attracted attention for future opto-spintronic devices.\nThe optical helicity induced torques on the magnetization, {\\it optical spin\ntorque}, have been observed in ferromagnetic thin films recently. However, the\ninterfacial effect of the optical spin torque in ferromagnet/nonmagnetic heavy\nmetal heterostructures have not been addressed so far, which are widely\nutilized to efficiently control magnetization via electrical means. Here, we\nstudied optical spin torque vectors in the ferromagnet/nonmagnetic heavy metal\nheterostructures and observed that in-plane field-like optical spin torque was\nsignificantly increased with decreasing ferromagnetic layer thicknesses. The\ninterfacial field-like optical spin torque was explained by the optical\nRashba-Edelstein effect caused by the structural inversion symmetry breaking.\nThis work will aid in the efficient optical manipulation of thin film\nnanomagnets using optical helicity.",
        "positive": "Smart packaging of electronics and integrated MEMS devices using LTCC: Low Temperature Cofired Ceramics (LTCC) has been a popular multi layer\nceramic (MCM) packaging material for many electronic applications. The main\nadvantage with LTCC would be its ability to embed a major part of the\nelectronic circuit within itself, apart from its enhanced RF functionality as\nagainst many lossy materials used. The advantages of LTCC in terms of frequency\nresponse, cost, ease of fabrication, etc over many other packaging materials\nare presented. The applicability of LTCC as a packaging material, circuit\nmounting material, substrate material or a base material for micro devices is\ndiscussed. Switches and filters fabricated on LTCC as a substrate are presented\nand their enhanced functionality is shown. Planar switches and RF MEMS switches\non LTCC are discussed with regard to their isolation, insertion losses, return\nlosses, repeatability, quality factor, parasitic effects and frequency\nresponse. Concern is also shown to parameters like actuation voltages,\nactuation times and complexity of fabrication. The parameters studied with\ndesign and fabrication of filters is also discussed, like Q factor, dispersive\neffects, limits on frequencies, etc. Discussion is also done with regard to\nLTCC as a base material for MEMS sensors and actuators and the performance\nvariables of the same. Fabrication process parameters are presented. The\nimportant issue of feasibility of integration with microelectronic integrated\ncircuitry is discussed and its effects are shown."
    },
    {
        "anchor": "An artificial spiking synapse made of molecules and nanoparticles: Molecule-based devices are envisioned to complement silicon devices by\nproviding new functions or already existing functions at a simpler process\nlevel and at a lower cost by virtue of their self-organization capabilities,\nmoreover, they are not bound to von Neuman architecture and this may open the\nway to other architectural paradigms. Here we demonstrate a device made of\nconjugated molecules and metal nanoparticles (NPs) which behaves as a spiking\nsynapse suitable for integration in neural network architectures. We\ndemonstrate that this device exhibits the main behavior of a biological\nsynapse. These results open the way to rate coding utilization of the NOMFET in\nperceptron and Hopfield networks. We can also envision the NOMFET as a building\nblock of neuroelectronics for interfacing neurons or neuronal logic devices\nmade from patterned neuronal cultures with solid-state devices and circuits.",
        "positive": "Broadband telecom transparency of semiconductor-coated metal nanowires:\n  more transparent than glass: Metallic nanowires (NW) coated with a high permittivity dielectric are\nproposed as means to strongly reduce the light scattering of the conducting NW,\nrendering them transparent at infrared wavelengths of interest in\ntelecommunications. Based on a simple, universal law derived from\nelectrostatics arguments, we find appropriate parameters to reduce the\nscattering efficiency of hybrid metal-dielectric NW by up to three orders of\nmagnitude as compared with the scattering efficiency of the homogeneous\nmetallic NW. We show that metal@dielectric structures are much more robust\nagainst fabrication imperfections than analogous dielectric@metal ones. The\nbandwidth of the transparent region entirely covers the near IR\ntelecommunications range. Although this effect is optimum at normal incidence\nand for a given polarization, rigorous theoretical and numerical calculations\nreveal that transparency is robust against changes in polarization and angle of\nincidence, and also holds for relatively dense periodic or random arrangements.\nA wealth of applications based on metal-NWs may benefit from such invisibility."
    },
    {
        "anchor": "Dissociation of O2 molecules on strained Pb(111) surfaces: By performing first-principles molecular dynamics calculations, we\nsystematically simulate the adsorption behavior of oxygen molecules on the\nclean and strained Pb(111) surfaces. The obtained molecular adsorption\nprecursor state, and the activated dissociation process for oxygen molecules on\nthe clean Pb surface are in good agreements with our previous static\ncalculations, and perfectly explains previous experimental observations [Proc.\nNatl. Acad. Sci. U.S.A. 104, 9204 (2007)]. In addition, we also study the\ninfluences of surface strain on the dissociation behaviors of O2 molecules. It\nis found that on the compressed Pb(111) surfaces with a strain value of larger\nthan 0.02, O2 molecules will not dissociate at all. And on the stretched\nPb(111) surfaces, O2 molecules become easier to approach, and the adsorption\nenergy of the dissociated oxygen atoms is larger than that on the clean Pb\nsurface.",
        "positive": "Spin Hamiltonian, Competing Small Energy Scales and Incommensurate Long\n  Range Order in the Highly Frustrated Gd3Ga5O12 Garnet Antiferromagnet: Despite the availability of a spin Hamiltonian for the Gd3Ga5O12 garnet (GGG)\nfor over twenty five years, there has so far been little theoretical insight\nregarding the many unusual low temperature properties of GGG. Here we\ninvestigate GGG in zero magnetic field using mean-field theory. We reproduce\nthe spin liquid-like correlations and, most importantly, explain the positions\nof the sharp peaks seen in powder neutron diffraction experiments. We show that\nit is crucial to treat accurately the long-range nature of the magnetic dipolar\ninteractions to allow for a determination of the small exchange energy scales\ninvolved in the selection of the experimental ordering wave vector. Our results\nshow that the incommensurate order in GGG is classical in nature, intrinsic to\nthe microscopic spin Hamiltonian and not caused by weak disorder."
    },
    {
        "anchor": "Spin-orbit engineering in transition metal dichalcogenide alloy\n  monolayers: Transition metal dichalcogenide (TMDC) monolayers are newly discovered\nsemiconductors for a wide range of applications in electronics and\noptoelectronics. Most studies have focused on binary monolayers that share\ncommon properties: direct optical bandgap, spin-orbit (SO) splittings of\nhundreds of meV, light-matter interaction dominated by robust excitons and\ncoupled spin-valley states of electrons. Studies on alloy-based monolayers are\nmore recent, yet they may not only extend the possibilities for TMDC\napplications through specific engineering but also help understanding the\ndifferences between each binary material. Here, we synthesized highly\ncrystalline Mo$_{(1-x)}$W$_{x}$Se$_2$ to show engineering of the direct optical\nbandgap and the SO coupling in ternary alloy monolayers. We investigate the\nimpact of the tuning of the SO spin splitting on the optical and polarization\nproperties. We show a non-linear increase of the optically generated valley\npolarization as a function of tungsten concentration, where 40% tungsten\nincorporation is sufficient to achieve valley polarization as high as in binary\nWSe2. We also probe the impact of the tuning of the conduction band SO spin\nsplitting on the bright versus dark state population i.e. PL emission\nintensity. We show that the MoSe2 PL intensity decreases as a function of\ntemperature by an order of magnitude, whereas for WSe2 we measure surprisingly\nan order of magnitude increase over the same temperature range (T=4-300K). The\nternary material shows a trend between these two extreme behaviors. These\nresults show the strong potential of SO engineering in ternary TMDC alloys for\noptoelectronics and applications based on electron spin- and valley-control.",
        "positive": "The interface between a polar perovskite oxide and silicon from\n  monoatomic lines: We report a study on the interface between polar high-k materials and the\nSi(001)-(2X1) reconstructed surface with LaAlO3 taken as a prototype material.\nThe construction of the interface is based on the prior growth of metal lines\nfollowed by oxidation, whose stability against oxygen coverage is studied.\nElectronic structure calculations within the Density Functional Theory\nframework help in building the interface and understanding its bonding\nstructure. Moreover, we computed a conduction band offset of 1.9 eV, in\nagreement with electronic applications requirement. The results may provide a\nguidance for interface processing."
    },
    {
        "anchor": "Strong Edge Stress in Molecularly Thin Organic$-$Inorganic Hybrid\n  Ruddlesden$-$Popper Perovskites and Modulations of Their Edge Electronic\n  Properties: Organic$-$inorganic hybrid Ruddlesden$-$Popper perovskites (HRPPs) have\ngained much attention for optoelectronic applications due to their high\nmoisture resistance, good processibility under ambient conditions, and long\nfunctional lifetimes. Recent success in isolating molecularly thin hybrid\nperovskite nanosheets and their intriguing edge phenomena have raised the need\nfor understanding the role of edges and the properties that dictate their\nfundamental behaviours. In this work, we perform a prototypical study on the\nedge effects in ultrathin hybrid perovskites by considering monolayer\n(BA)$_2$PbI$_4$ as a representative system. Based on first-principles\nsimulations of nanoribbon models, we show that in addition to significant\ndistortions of the octahedra network at the edges, strong edge stresses are\nalso present in the material. Structural instabilities that arise from the edge\nstress could drive the relaxation process and dominate the morphological\nresponse of edges in practice. A clear downward shift of the bands at the\nnarrower ribbons, as indicative of the edge effect, facilitates the separation\nof photo-excited carriers (electrons move towards the edge and holes move\ntowards the interior part of the nanosheet). Moreover, the desorption energy of\nthe organic molecule can also be much lower at the free edges, making it easier\nfor functionalization and/or substitution events to take place. The findings\nreported in this work elucidate the underlying mechanisms responsible for edge\nstates in HRPPs and will be important in guiding the rational design and\ndevelopment of high-performance layer$-$edge devices.",
        "positive": "Phenomenological theory of photomagnetoelectric effects Application to\n  the directional photovoltaic effect in LiNbO3: We propose a phenomenological theory working out light illumination effects\non the equilibrium values of any macroscopic crystal tensor (polarization,\nmagnetization, susceptibilities, strain tensor, elastic coefficients...). it\nalso encompasses non-equilibrium light-induced quantities such as an electric\ncurrent and heat flow. We use a single phenomenological approach based on\nWigner spherical functions for predicting symmetry-related photo-induced\nphenomena, including photovoltaic, photoelectric, photomagnetic,\nphotorefractive, photogalvanic, photoelastic and optic rectification phenomena.\nFor each crystal magnetic point group and each tensor type, response functions\nare calculated vs. the propagation and polarization directions of the incident\nelectromagnetic beam. Their forms are determined by crystal and light symmetry\ngroup interconnection. We pay special attention to time and space reversal\nsymmetries, which play a dominant role in the intricate symmetry breakdowns of\nmultiferroic materials. Photovoltaic and photo-magneto-electric effects in\nLiNbO3 illustrate our theory."
    },
    {
        "anchor": "Readout of a antiferromagnetic spintronics systems by strong exchange\n  coupling of Mn2Au and Permalloy: In antiferromagnetic spintronics, the read-out of the staggered magnetization\nor Neel vector is the key obstacle to harnessing the ultra-fast dynamics and\nstability of antiferromagnets for novel devices. Here, we demonstrate strong\nexchange coupling of Mn2Au, a unique metallic antiferromagnet that exhibits\nNeel spin-orbit torques, with thin ferromagnetic Permalloy layers. This allows\nus to benefit from the well-estabished read-out methods of ferromagnets, while\nthe essential advantages of antiferromagnetic spintronics are retained. We show\none-to-one imprinting of the antiferromagnetic on the ferromagnetic domain\npattern. Conversely, alignment of the Permalloy magnetization reorients the\nMn2Au Neel vector, an effect, which can be restricted to large magnetic fields\nby tuning the ferromagnetic layer thickness. To understand the origin of the\nstrong coupling, we carry out high resolution electron microscopy imaging and\nwe find that our growth yields an interface with a well-defined morphology that\nleads to the strong exchange coupling.",
        "positive": "Observation of the Critical State to Multiple-Type Dirac Semimetal\n  Phases in KMgBi: Dirac semimetals (DSMs) are classified into different phases based on the\ntypes of the Dirac fermions. Tuning the transition among different types of the\nDirac fermions in one system remains challenging. Recently, KMgBi was predicted\nto be located at a critical state that various types of Dirac fermions can be\ninduced owing to the existence of a flat band. Here, we carried out systematic\nstudies on the electronic structure of KMgBi single crystal by combining\nangle-resolve photoemission spectroscopy (ARPES) and scanning tunneling\nmicroscopy/spectroscopy (STM/STS). The flat band was clearly observed near the\nFermi level. We also revealed a small bandgap of ~ 20 meV between the flat band\nand the conduction band. These results demonstrate the critical state of KMgBi\nthat transitions among various types of Dirac fermions can be tuned in one\nsystem."
    },
    {
        "anchor": "Crystal growth and structural analysis of perovskite chalcogenide\n  BaZrS$_3$ and Ruddlesden-Popper phase Ba$_3$Zr$_2$S$_7$: Perovskite chalcogenides are gaining substantial interest as an emerging\nclass of semiconductors for optoelectronic applications. High quality samples\nare of vital importance to examine their inherent physical properties. We\nreport the successful crystal growth of the model system, BaZrS$_3$ and its\nRuddlesden-Popper phase Ba$_3$Zr$_2$S$_7$ by flux method. X-ray diffraction\nanalyses showed space group of $Pnma$ with lattice constants of $a$ = 7.056(3)\n\\AA\\/, $b$ = 9.962(4) \\AA\\/, $c$ = 6.996(3) \\AA\\/ for BaZrS$_3$ and $P4_2/mnm$\nwith $a$ = 7.071(2) \\AA\\/, $b$ = 7.071(2) \\AA\\/, $c$ = 25.418(5) \\AA\\/ for\nBa$_3$Zr$_2$S$_7$. Rocking curves with full-width-at-half-maximum of\n0.011$^\\circ$ for BaZrS$_3$ and 0.027$^\\circ$ for Ba$_3$Zr$_2$S$_7$ were\nobserved. Pole figure analysis, scanning transmission electron microscopy\nimages and electron diffraction patterns also establish high quality of grown\ncrystals. The octahedra tilting in the corner-sharing octahedra network are\nanalyzed by extracting the torsion angles.",
        "positive": "Orowan strengthening with thermal activation: Orowan strengthening is a primary way of strengthening metallic materials.The\neffect of temperature on the Orowan strengthening mechanism is still debatable\nin the present day.In this study,the effect of temperature on the Orowan\nstrengthening mechanism is systematically investigated,a thermal activation\nOrowan strengthening mechanism is developed,and the corresponding Orowan stress\nis deduced.The results indicate that the obstacle scales substantially affect\nthe thermal activation-based dislocation that bypasses the precipitates\nprocesses.In small obstacle scales,the thermal activation contribution to\nOrowan stress cannot be ignored;while in large obstacle scales,the thermal\nactivation contribution can be ignored even at high temperatures.In addition to\ntemperature, the effects of shear modulus,strain rate, and dislocation density\nare investigated on Orowan stress.This work not only provides new insight into\nthe Orowan strengthening mechanism but also aids in the development of new\nhigh-temperature structural materials."
    },
    {
        "anchor": "Negative-U and polaronic behavior of the Zn-O divacancy in ZnO: Hybrid functional calculations reveal the Zn-O divacancy in ZnO, consisting\nof adjacent Zn and O vacancies, as an electrically active defect exhibiting\ncharge states ranging from $2+$ to $2-$ within the band gap. Notably, the\ndivacancy retains key features of the monovacancies, namely the\nnegative-\\textit{U} behavior of the O vacancy, and the polaronic nature of the\nZn vacancy. The thermodynamic charge-state transition levels associated with\nthe negative-\\textit{U} behavior $\\varepsilon$($0$/$2-$),\n$\\varepsilon$($-$/$2-$) and $\\varepsilon$($0$/$-$) are predicted to occur at\n0.22, 0.42 and 0.02 eV below the conduction band minimum, respectively,\nresulting in \\textit{U} = $-$0.40 eV. These transition levels are moved closer\nto the conduction band and the magnitude of \\textit{U} is lowered compared to\nthe values for the O vacancy. Further, the interaction with hydrogen has been\nexplored, where it is shown that the divacancy can accommodate up to three H\natoms. The first two H atoms prefer to terminate O dangling bonds at the Zn\nvacancy, while the geometrical location of the third depends on the Fermi-level\nposition. The calculated electrical properties of the divacancy are in\nexcellent agreement with those reported for the E4 center observed by\ndeep-level transient spectroscopy, challenging the O vacancy as a candidate for\nthis level.",
        "positive": "The effect of substrate temperature on cadmium telluride films in high\n  temperature vapor deposition process: Physical vapor high-temperature deposition of CdTe thin films is one of the\nmain methods for preparing high-efficiency CdTe solar cells, but\nhigh-temperature deposition also has an impact on the internal structure of the\nfilm. The difference in thermal expansion coefficients between the substrate\nand CdTe leads to the generation of internal stress in the CdTe thin film\nduring the cooling process. In this work, we prepared thin films with different\nsubstrate temperatures using a homemade GVD device, and observed by SEM that\nthe crystallization quality of the film gradually improved with the increase of\nsubstrate temperature, but accompanied by the shift of XRD peak position. We\ncalculated the internal stress situation of the film by the shift amount, and\nthe possible causes of stress generation were speculated by the results of TEM\nand SAED to be the combined effects of the different thermal expansion\ncoefficients between the substrate and the film and the stacking fault defects\ninside the film."
    },
    {
        "anchor": "Spheroidal Particle Stability in Semi-Solid Processing: A model for diffusion-controlled spherical particle growth is presented and\nsolved numerically, showing how, on cooling at sufficient rate from a given\nfraction solid, growth velocity first increases, and then decreases rapidly\nwhen solute fields of adjacent particles overlap. An approximate analytical\nsolution for the spherical particle growth velocity is then developed and shown\nto be valid until the solute fields begin to overlap. A particle stability\nmodel is next presented, building on the above analytic solution. This model\npermits prediction of the maximum cooling rate at which a semi-solid slurry or\nreheated semi-solid billet can be cooled while still retaining the spherical\ngrowth morphology. The model shows that particle stability is favored by high\nparticle density, high fraction solid and low cooling rate. The predictions of\nthe stability model are found to be in good quantitative agreement with\nexperimental data collected for Al-4.5wt%Cu alloy. Engineering applications of\nthe results obtained are discussed.",
        "positive": "Interfacial closure of contacting surfaces: Understanding the contact between solid surfaces is a long standing problem\nwhich has a strong impact on the physics of many processes such as adhesion,\nfriction, lubrication and wear. Experimentally, the investigation of\nsolid/solid interfaces remains challenging today, due to the lack of\nexperimental techniques able to provide sub-nanometer scale information on\ninterfaces buried between millimeters of materials. Yet, a strong interest\nexists improving the modeling of contact mechanics of materials in order to\nadjust their interface properties (e.g. thermal transport, friction). We show\nhere that the essential features of the residual gap between contacting\nsurfaces can be measured using high energy X-ray synchrotron reflectivity. The\npresence of this nano-gap is general to the contact of solids. In some special\ncase however, it can be removed when attractive forces take over repulsive\ncontributions, depending on both height and wavelength of asperity\ndistributions (roughness). A criterion for this instability is established in\nthe standard case of van der Waals attractive forces and elastic asperity\ncompression repulsive forces (Hertz model). This collapse instability is\nconfirmed experimentally in the case of silicon direct bonding, using\nhigh-energy X-ray synchrotron reflectivity and adhesion energy measurements.\nThe possibility to achieve fully closed interfaces at room temperature opens\ninteresting perspectives to build stronger assemblies with smaller thermal\nbudgets."
    },
    {
        "anchor": "A compact approach to higher-resolution resonant inelastic X-ray\n  scattering detection using photoelectrons: The detection of inelastically scattered soft X-rays with high energy\nresolution usually requires large grating spectrometers. Recently,\nphotoelectron spectrometry for analysis of X-rays (PAX) has been rediscovered\nfor modern spectroscopy experiments at synchrotron light sources. By converting\nscattered photons to electrons and using an electron energy analyser, the\nenergy resolution for resonant inelastic X-ray scattering (RIXS) becomes\ndecoupled from the X-ray spot size and instrument length. In this work, we\ndevelop PAX towards high energy resolution using a modern photoemission\nspectroscopy setup studying Ba2Cu3O4Cl2 at the Cu L3-edge. We measure a\nmomentum transfer range of 24% of the first Brillouin zone simultaneously. Our\nresults hint at the observation of a magnon excitation below 100 meV energy\ntransfer and show intensity variations related to the dispersion of\ndd-excitations. With dedicated setups, PAX can become an alternative to the\nbest and largest RIXS instruments, while at the same time opening new\nopportunities to acquire RIXS at a range of momentum transfers simultaneously\nand combine it with angle-resolved photoemission spectroscopy in a single\ninstrument.",
        "positive": "Hard magnetic properties in nanoflake van der Waals Fe3GeTe2: Two dimensional (2D) van der Waals (vdW) materials have demonstrated\nfascinating optical, electrical and thickness-dependent characteristics. These\nhave been explored by numerous authors but reports on magnetic properties and\nspintronic applications of 2D vdW materials are scarce by comparison. By\nperforming anomalous Hall effect transport measurements, we have characterised\nthe thickness dependent magnetic properties of single crystalline vdW Fe3GeTe2.\nThe nanoflakes of this vdW metallic material exhibit a single hard magnetic\nphase with a near square-shaped magnetic loop, large coercivity (up to 550 mT\nat 2 K), a Curie temperature near 200 K and strong perpendicular magnetic\nanisotropy. Using criticality analysis, we confirmed the existence of magnetic\ncoupling between vdW atomic layers and obtained an estimated coupling length of\n~ 5 vdW layers in Fe3GeTe2. Furthermore, the hard magnetic behaviour of\nFe3GeTe2 can be well described by a proposed model. The magnetic properties of\nFe3GeTe2 highlight its potential for integration into vdW magnetic\nheterostructures, paving the way for spintronic research and applications based\non these devices."
    },
    {
        "anchor": "The role of non-spherical double counting in DFT+DMFT: total energy and\n  structural optimization of pnictide superconductors: A simple scheme for avoiding non-spherical double counting in the combination\nof density func- tional theory with dynamical mean-field theory (DFT+DMFT)is\ndeveloped. It is applied to total- energy calculations and structural\noptimization of the pnictide superconductor LaFeAsO. The results are compared\nto a recently proposed \"exact\" double-counting formulation. Both schemes bring\nthe optimized Fe-As interatomic distance close to the experimental value. This\nresolves the long stand- ing controversy between DFT+DMFT and experiment for\nthe structural optimization of LaFeAsO.",
        "positive": "Electron-hole and plasmon excitations in 3d transition metals: Ab initio\n  calculations and inelastic x-ray scattering measurements: We report extensive all-electron time-dependent density-functional\ncalculations and nonresonant inelastic x-ray scattering measurements of the\ndynamical structure factor of 3d transition metals. For small wave vectors, a\nplasmon peak is observed which is well described by our calculations. At large\nwave vectors, both theory and experiment exhibit characteristic low-energy\nelectron-hole excitations of d character which correlate with the presence of d\nbands below and above the Fermi level. Our calculations, which have been\ncarried out in the random-phase and adiabatic local-density approximations, are\nfound to be in remarkable agreement with the measured dynamical structure\nfactor of Sc and Cr at energies below the semicore onset energy (M-edge) of\nthese materials."
    },
    {
        "anchor": "Epitaxial stabilization of SrCu$_3$O$_4$ with infinite Cu$_{3/2}$O$_2$\n  layers: We report the epitaxial thin film synthesis of SrCu$_3$O$_4$ with infinitely\nstacked Cu$_3$O$_4$ layers composed of edge-sharing CuO$_4$ square-planes,\nusing molecular beam epitaxy. Experimental and theoretical characterizations\nshowed that this material is a metastable phase that can exist by applying\ntensile biaxial strain from the (001)-SrTiO$_3$ substrate. SrCu$_3$O$_4$ shows\nan insulating electrical resistivity in accordance with the Cu$^{2+}$ valence\nstate revealed X-ray photoelectron spectroscopy. First-principles calculations\nalso indicated that the unoccupied $d_{3z^2-r^2}$ band becomes substantially\nstabilized owing to the absence of apical anions, in contrast to\n$A_2$Cu$_3$O$_4$Cl$_2$ ($A = $Sr, Ba) with an $A_2$Cl$_2$ block layer and\ntherefore a trans-CuO$_4$Cl$_2$ octahedron. These results suggest that\nSrCu$_3$O$_4$ is a suitable parent material for electron-doped\nsuperconductivity based on the Cu$_3$O$_4$ plane.",
        "positive": "Hall carrier density and magnetoresistance measurements in thin film\n  vanadium dioxide across the metal-insulator transition: Temperature dependent magneto-transport measurements in magnetic fields of up\nto 12 Tesla were performed on thin film vanadium dioxide (VO2) across the\nmetal-insulator transition (MIT). The Hall carrier density increases by 4\norders of magnitude at the MIT and accounts almost entirely for the resistance\nchange. The Hall mobility varies little across the MIT and remains low,\n~0.1cm2/V sec. Electrons are found to be the major carriers on both sides of\nthe MIT. Small positive magnetoresistance in the semiconducting phase is\nmeasured."
    },
    {
        "anchor": "Microscopic modeling of the effect of phonons on the optical properties\n  of solid-state emitters: Understanding the effect of vibrations in optically active nano systems is\ncrucial for successfully implementing applications in molecular-based\nelectro-optical devices, quantum information communications, single photon\nsources, and fluorescent markers for biological measurements. Here, we present\na first-principles microscopic description of the role of phonons on the\nisotopic shift presented in the optical emission spectrum associated to the\nnegatively charged silicon-vacancy color center in diamond. We use the\nspin-boson model and estimate the electron-phonon interactions using a\nsymmetrized molecular description of the electronic states and a force-constant\nmodel to describe molecular vibrations. Group theoretical arguments and\ndynamical symmetry breaking are presented in order to explain the optical\nproperties of the zero-phonon line and the isotopic shift of the phonon\nsideband.",
        "positive": "Creation and control of a two-dimensional electron liquid at the bare\n  SrTiO3 surface: Many-body interactions in transition-metal oxides give rise to a wide range\nof functional properties, such as high-temperature superconductivity, colossal\nmagnetoresistance, or multiferroicity. The seminal recent discovery of a\ntwo-dimensional electron gas (2DEG) at the interface of the insulating oxides\nLaAlO3 and SrTiO3 represents an important milestone towards exploiting such\nproperties in all-oxide devices. This conducting interface shows a number of\nappealing properties, including a high electron mobility, superconductivity,\nand large magnetoresistance and can be patterned on the few-nanometer length\nscale. However, the microscopic origin of the interface 2DEG is poorly\nunderstood. Here, we show that a similar 2DEG, with an electron density as\nlarge as 8x10^13 cm^-2, can be formed at the bare SrTiO3 surface. Furthermore,\nwe find that the 2DEG density can be controlled through exposure of the surface\nto intense ultraviolet (UV) light. Subsequent angle-resolved photoemission\nspectroscopy (ARPES) measurements reveal an unusual coexistence of a light\nquasiparticle mass and signatures of strong many-body interactions."
    },
    {
        "anchor": "Luminescence of non-bridging oxygen hole centers as a marker of particle\n  irradiation of \u03b1-quartz: The origin of the \"red\" emission bands in the 600 nm-700 nm region, observed\nin quartz crystals used for luminescence dating and environmental dosimetry, is\nstill controversial. Their reported spectral and lifetime characteristics are\noften similar to those of oxygen dangling bonds (\"non-bridging oxygen hole\ncenters, NBOHCs\") in glassy silicon dioxide. The presence of these \"surface\nradical type\" centers in quartz crystal requires sites with highly disordered\nlocal structure forming nano-voids characteristic to the structure of glassy\nSiO2. Such sites are introduced in the tracks of nuclear particles\n({\\alpha}-irradiation, neutrons, ions). In case of electrons they are created\nonly at large doses (>5 GGy), approaching amorphization threshold. This study\nreports a comparison of NBOHC photoluminescence in synthetic quartz and silica\nglass irradiated by neutrons or 2.5 MeV electrons, and suggests that the red\nNBOHC photoluminescence band in quartz may serve as a selective marker of an\nexposure to particle irradiation. It can be distinguished from other red-region\nluminescence bands by lifetimes in 5-25 {\\mu}s range, characteristic\nvibrational structures in the low-temperature spectra and presence of resonance\nexcitation band at ~620 nm.",
        "positive": "Direct evidence of weakly dispersed and strongly anharmonic optical\n  phonons in hybrid perovskites: Hybrid organolead perovskites (HOP) have started to establish themselves in\nthe field of photovoltaics, mainly due to their great optoelectronic properties\nand steadily improving solar cell efficiency. Study of the lattice dynamics is\nkey in understanding the electron-phonon interactions at play, responsible for\nsuch properties. Here, we investigate, via neutron and Raman spectroscopies,\nthe optical phonon spectrum of four different HOP single crystals: MAPbBr$_3$,\nFAPbBr$_3$, MAPbI$_3$, and $\\alpha$-FAPbI$_3$. Low temperature spectra reveal\nweakly dispersive optical phonons, at energies as low as 2-5~meV, which seem to\nbe the origin of the limit of the charge carriers mobilities in these\nmaterials. The temperature dependence of our neutron spectra shows as well a\nsignificant anharmonic behaviour, resulting in optical phonon overdamping at\ntemperatures as low as 80~K, questionning the validity of the quasi-particle\npicture for the low energy optical modes at room temperature where the solar\ncells operate."
    },
    {
        "anchor": "Manipulation of Magnetic Solitons on Odd-Numbered Macrospin Rings: We report simulations of a frustrated odd-numbered macrospin ring system,\nwith full point dipolar interactions, driven by a rotating uniform applied\nmagnetic field of constant magnitude. The system is designed with\nequally-spaced radially-aligned macrospins, which must carry a frustrated\nsoliton defect in its ground state. It is shown how correctly tuning the\napplied field magnitude can allow for non-trivial unidirectional propagation of\nthe soliton, the required directional pressure acquired via the curvature of\nthe ring. Furthermore, the system, which may be employed as a multiple rotation\ncounter, is tested for robustness against quenched disorder as would be present\nin an experimental realization.",
        "positive": "Self-trapped electrons and holes in PbBr$_2$ crystals: We have directly observed self-trapped electrons and holes in PbBr$_{2}$\ncrystals with electron-spin-resonance (ESR) technique. The self-trapped states\nare induced below 8 K by two-photon interband excitation with pulsed\n120-fs-width laser light at 3.10 eV. Spin-Hamiltonian analyses of the ESR\nsignals have revealed that the self-trapping electron centers are the dimer\nmolecules of Pb$_2$$^{3+}$ along the crystallographic a axis and the\nself-trapping hole centers are those of Br$_2$$^-$ with two possible\nconfigurations in the unit cell of the crystal. Thermal stability of the\nself-trapped electrons and holes suggests that both of them are related to the\nblue-green luminescence band at 2.55 eV coming from recombination of spatially\nseparated electron-hole pairs."
    },
    {
        "anchor": "A phase field model for elastic-gradient-plastic solids undergoing\n  hydrogen embrittlement: We present a gradient-based theoretical framework for predicting hydrogen\nassisted fracture in elastic-plastic solids. The novelty of the model lies in\nthe combination of: (i) stress-assisted diffusion of solute species, (ii)\nstrain gradient plasticity, and (iii) a hydrogen-sensitive phase field fracture\nformulation, inspired by first principles calculations. The theoretical model\nis numerically implemented using a mixed finite element formulation and several\nboundary value problems are addressed to gain physical insight and showcase\nmodel predictions. The results reveal the critical role of plastic strain\ngradients in rationalising decohesion-based arguments and capturing the\ntransition to brittle fracture observed in hydrogen-rich environments. Large\ncrack tip stresses are predicted, which in turn raise the hydrogen\nconcentration and reduce the fracture energy. The computation of the steady\nstate fracture toughness as a function of the cohesive strength shows that\ncleavage fracture can be predicted in otherwise ductile metals using sensible\nvalues for the material parameters and the hydrogen concentration. In addition,\nwe compute crack growth resistance curves in a wide variety of scenarios and\ndemonstrate that the model can appropriately capture the sensitivity to: the\nplastic length scales, the fracture length scale, the loading rate and the\nhydrogen concentration. Model predictions are also compared with fracture\nexperiments on a modern ultra-high strength steel, AerMet100. A promising\nagreement is observed with experimental measurements of threshold stress\nintensity factor $K_{th}$ over a wide range of applied potentials.",
        "positive": "Electronic Structure, Phonons and Dielectric Anomaly in Ferromagnetic\n  Insulating Double Perovskite La2NiMnO6: Using first-principles density functional calculations, we study the\nelectronic and magnetic properties of ferromagnetic insulating\ndouble-perovskite compound La2NiMnO6, which has been reported to exhibit\ninteresting magnetic field sensitive dielectric anomaly as a function of\ntemperature. Our study reveals existence of very soft infra-red active phonons\nthat couple strongly with spins at the Ni and Mn sites through modification of\nthe super-exchange interaction. We suggest that these modes are the origin for\nobserved dielectric anomaly in La2NiMnO6."
    },
    {
        "anchor": "Fabrication and characterization of a Ni-Mn-Ga uniaxially textured\n  freestanding film deposited by DC magnetron sputtering: Homogeneous freestanding films have been obtained by the direct current (DC)\nmagnetron sputtering technique using a sacrificial layer. After annealing, the\nfilms are crystallized with a strong out-of-plane texture along the (022)\ndirection. The stoichiometry of the annealed films is close to the target\ncomposition and leads to a martensitic transformation around 255K. The annealed\nfilms demonstrate ferromagnetic behavior with a Curie temperature of about\n362K. The magnetization process has been studied on the both states and during\nthe martensitic transition. The saturation magnetizations have been determined\nby fitting the experimental data with a saturation approach law in the range\n1-5T. Results show the saturation magnetization of the martensite is around 10%\nhigher than that of the austenite. A model based on intrinsic magnetic\nproperties of each state allowing the description of the magnetization M=f (H,\nT) of such polycrystalline films during the martensitic transformation is\npresented. The mass fraction of martensite inside the austenite phase can be\ndetermined using this model. The shape memory effect is analyzed both by\nscanning electron microscopy and by optical microscopy with in-situ measurement\nof the resistance temperature dependence.",
        "positive": "Perovskite oxide heterojunction for Rashba-Dresselhaus assisted\n  antiferromagnetic spintronics: A major impediment towards realizing technologies based on the emerging\nprinciples of antiferromagnetic spintronics is the shortage of suitable\nmaterials. In this paper, we propose a design of polar|nonpolar\nheterostructures of perovskite oxides, where a single unit cell of SrIrO3 is\nsandwiched between a thin film of LaAlO3 and a substrate of SrTiO3. Our\ncalculations within the framework of density-functional theory + Hubbard U +\nspin-orbit coupling reveal a two-dimensional conducting layer with electron and\nhole pockets at the interface, exhibiting a strong anisotropic\nRashba-Dresselhaus effect along with noncollinear antiferromagnetism,\nindicating the possibility of realizing a spin-orbit torque. An insightful\nphysical model for the anisotropic Rashba-Dresselhaus effect nicely interprets\nour results, providing an estimate for the Rashba-Dresselhaus coefficients and\nillustrating pseudospin orientation.We also observe a proximity-induced\nprominent Rashba-like effect for Ti 3d empty bands. Our results suggest that\nthe heterostructure may possess the essential ingredients for antiferromagnetic\nspintronics, deserving experimental verification."
    },
    {
        "anchor": "Theory of Distinct Crystal Structures of Polymerized Fullerides AC60,\n  A=K, Rb, Cs: the Specific Role of Alkalis: The polymer phases of AC60 form distinct crystal structures characterized by\nthe mutual orientations of the (C60-)n chains. We show that the direct electric\nquadrupole interaction between chains always favors the orthorhombic structure\nPmnn with alternating chain orientations. However the specific quadrupolar\npolarizability of the alkali metal ions leads to an indirect interchain\ncoupling which favors the monoclinic structure I2/m with equal chain\norientations. The competition between direct and indirect interactions explains\nthe structural difference between KC60 and RbC60, CsC60.",
        "positive": "Neutron tomography of magnetic Majorana fermions in a proximate quantum\n  spin liquid: Quantum matter provides an effective vacuum out of which arise emergent\nparticles not corresponding to any experimentally detected elementary particle.\nTopological quantum materials in particular have become a focus of intense\nresearch in part because of the remarkable possibility to realize Majorana\nfermions, with their potential for new, decoherence-free quantum computing\narchitectures. In this paper we undertake a study on high-quality single\ncrystal of $\\alpha-RuCl_3$ which has been identified as a material realizing a\nproximate Kitaev state, a topological quantum state with magnetic Majorana\nfermions. Four-dimensional tomographic reconstruction of dynamical correlations\nmeasured using neutrons is uniquely powerful for probing such magnetic states.\nWe discover unusual signals, including an unprecedented column of scattering\nover a large energy interval around the Brillouin zone center which is\nremarkably stable with temperature. This is straightforwardly accounted for in\nterms of the Majorana excitations present in Kitaev's topological quantum spin\nliquid. Other, more delicate, features in the scattering can be transparently\nassociated with perturbations to an ideal model. This opens a window on\nemergent magnetic Majorana fermions in correlated materials."
    },
    {
        "anchor": "Recycling End-of-life Polycarbonate in Steelmaking; $\\textit{Ab Initio}$\n  Study of Carbon Dissolution in Molten Iron: The scarcity of fossil fuels as carbon resources has motivated the\nsteelmaking industry to search for new carbon sources such as end-of-life\npolymeric products. Using $\\textit{ab initio}$ molecular dynamics simulation,\nwe demonstrate that 41% of polycarbonate's carbon content is readily dissolved\nin molten iron's interface at $T$ = 1823 K which is comparable to graphite with\n$\\sim$ 58% carbon content dissolution. More importantly, we demonstrate that\npolycarbonate's hydrogen content does not dissolve in molten iron but rather\nescape in gaseous form. Therefore, waste polycarbonate constitutes a feasible\ncarbon source for steelmaking.",
        "positive": "Magnon-phonon interactions enhance the gap at the Dirac point in the\n  spin-wave spectra of CrI$_3$ two-dimensional magnets: Recent neutron-diffraction experiments in honeycomb CrI$_3$ quasi-2D\nferromagnets have evinced the existence of a gap at the Dirac point in their\nspin-wave spectra. The existence of this gap has been attributed to strong\nin-plane Dzyaloshinskii-Moriya or Kitaev (DM/K) interactions and suggested to\nset the stage for topologically protected edge states to sustain\nnon-dissipative spin transport. We perform state-of-the-art simulations of the\nspin-wave spectra in monolayer CrI$_3$, based on time-dependent\ndensity-functional perturbation theory (TDDFpT) and fully accounting for\nspin-orbit couplings (SOC) from which DM/K interactions ultimately stem. While\nour results are in qualitative agreement with experiments, the computed TDDFpT\nmagnon gap at the Dirac point is found to be 0.47~meV, roughly 6 times smaller\nthan the most recent experimental estimates, so questioning that intralayer\nanisotropies alone can explain the observed gap. Lattice-dynamical\ncalculations, performed within density-functional perturbation theory (DFpT),\nindicate that a substantial degeneracy and a strong coupling between\nvibrational and magnetic excitations exist in this system, providing a possible\nadditional gap-opening mechanism in the spin-wave spectra. In order to pursue\nthis path, we introduce an interacting magnon-phonon Hamiltonian featuring a\nlinear coupling between lattice and spin fluctuations, enabled by the magnetic\nanisotropy induced by SOC. Upon determination of the relevant interaction\nconstants by DFpT and supercell calculations, this model allows us to propose\nmagnon-phonon interactions as an important microscopic mechanism responsible\nfor the enhancement of the gap in the range of $\\approx 4$~meV around the Dirac\npoint of the CrI$_3$ monolayer."
    },
    {
        "anchor": "Electrical tuning of robust layered antiferromagnetism in MXene\n  monolayer: A-type antiferromagnetism, with an in-plane ferromagnetic order and the\ninterlayer antiferromagnetic coupling, owns inborn advantages for electrical\nmanipulations but is naturally rare in real materials except in those\nartificial antiferromagnetic heterostructures. Here, a robust layered\nantiferromagnetism with a high N\\'eel temperature is predicted in a MXene\nCr$_2$CCl$_2$ monolayer, which provides an ideal platform as a magnetoelectric\nfield effect transistor. Based on first-principles calculations, we demonstrate\nthat an electric field can induce the band splitting between spin-up and\nspin-down channels. Although no net magnetization is generated, the inversion\nsymmetry between the lower Cr layer and the upper Cr layer is broken via\nelectronic cloud distortions. Moreover, this electric field can be replaced by\na proximate ferroelectric layer for nonvolatility. The magneto-optic Kerr\neffect can be used to detect this magnetoelectricity, even if it is a collinear\nantiferromagnet with zero magnetization.",
        "positive": "Magnetoelastic coupling enabled tunability of magnon spin current\n  generation in 2D antiferromagnets: We theoretically investigate the magnetoelastic coupling (MEC) and its effect\non magnon transport in two-dimensional antiferromagnets with a honeycomb\nlattice. MEC coeffcient along with magnetic exchange parameters and spring\nconstants are computed for monolayers of transition metal trichalcogenides with\nN\\'eel order ($\\text{MnPS}_3$ and $\\text{VPS}_3$) and zigzag order\n($\\text{CrSiTe}_3$, $\\text{NiPS}_3$ and $\\text{NiPSe}_3$) by $ab$ $initio$\ncalculations. Using these parameters, we predict that the spin-Nernst\ncoefficient is significantly enhanced due to magnetoelastic coupling. Our study\nshows that although Dzyaloshinskii-Moriya interaction can produce spin Nernst\neffect in these materials, other mechanisms such as magnon-phonon coupling\nshould be taken into account. We also demonstrate that the magnetic anisotropy\nis an important factor for control of magnon-phonon hybridization and\nenhancement of the Berry curvature and thus the spin-Nernst coefficient. Our\nresults pave the way towards gate tunable spin current generation in 2D magnets\nby SNE via electric field modulation of MEC and anisotropy."
    },
    {
        "anchor": "Universal radiation tolerant semiconductor: Radiation tolerance is determined as the ability of crystalline materials to\nwithstand the accumulation of the radiation induced disorder. Nevertheless, for\nsufficiently high fluences, in all by far known semiconductors it ends up with\neither very high disorder levels or amorphization. Here we show that gamma/beta\ndouble polymorph Ga2O3 structures exhibit remarkably high radiation tolerance.\nSpecifically, for room temperature experiments, they tolerate a disorder\nequivalent to hundreds of displacements per atom, without severe degradations\nof crystallinity; in comparison with, e.g., Si amorphizable already with the\nlattice atoms displaced just once. We explain this behavior by an interesting\ncombination of the Ga- and O- sublattice properties in gamma-Ga2O3. In\nparticular, O-sublattice exhibits a strong recrystallization trend to recover\nthe face-centered-cubic stacking despite the stronger displacement of O atoms\ncompared to Ga during the active periods of cascades. Notably, we also\nexplained the origin of the beta-to-gamma Ga2O3 transformation, as a function\nof the increased disorder in beta-Ga2O3 and studied the phenomena as a function\nof the chemical nature of the implanted atoms. As a result, we conclude that\ngamma/beta double polymorph Ga2O3 structures, in terms of their radiation\ntolerance properties, benchmark a class of universal radiation tolerant\nsemiconductors.",
        "positive": "First-principles phase-coherent transport in metallic nanotubes with\n  realistic contacts: We present first-principles calculations of phase coherent electron transport\nin a carbon nanotube (CNT) with realistic contacts. We focus on the zero-bias\nresponse of open metallic CNT's considering two archetypal contact geometries\n(end and side) and three commonly used metals as electrodes (Al, Au, and Ti).\nOur ab-initio electrical transport calculations make, for the first time,\nquantitative predictions on the contact transparency and the transport\nproperties of finite metallic CNT's. Al and Au turn out to make poor contacts\nwhile Ti is the best option of the three. Additional information on the CNT\nband mixing at the contacts is also obtained."
    },
    {
        "anchor": "Superconductivity at ~ 0.049 K in Laves phase HfZn2 predicted by first\n  principles: We report the superconductivity at Tc ~ 0.049 K in Laves phase HfZn2. Based\non the first principles method we have studied the details structural and\nelectronic properties of HfZn2 according to which there are 4.67 states eV-1\nfu-1 at Fermi level. Using this value we calculate the specific heat\ncoefficient {\\gamma} theoretically as 10.97 mJ/ K2 mol and then systematically\ncalculate the electron-phonon coupling constant {\\lambda} as 0.45. Finally\napplying these values in McMillan formula we get the superconducting critical\ntemperature of HfZn2 as approximately 0.049 K.",
        "positive": "Next-generation non-local van der Waals density functional: The fundamental ideas for a non-local density functional theory -- capable of\nreliably capturing van der Waals interaction -- were already conceived in the\n1990's. In 2004, a seminal paper introduced the first practical non-local\nexchange-correlation functional called vdW-DF, which has become widely\nsuccessful and laid the foundation for much further research. However, since\nthen, the functional form of vdW-DF has remained unchanged. Several successful\nmodifications paired the original functional with different (local) exchange\nfunctionals to improve performance and the successor vdW-DF2 also updated one\ninternal parameter. Bringing together different insights from almost two\ndecades of development and testing, we present the next-generation non-local\ncorrelation functional called vdW-DF3, in which we change the functional form\nwhile staying true to the original design philosophy. Although many popular\nfunctionals show good performance around the binding separation of van der\nWaals complexes, they often result in significant errors at larger separations.\nWith vdW-DF3, we address this problem by taking advantage of a recently\nuncovered and largely unconstrained degree of freedom within the vdW-DF\nframework that can be constrained through empirical input, making our\nfunctional semi-empirical. For two different parameterizations, we benchmark\nvdW-DF3 against a large set of well-studied test cases and compare our results\nwith the most popular functionals, finding good performance in general for a\nwide array of systems and a significant improvement in accuracy at larger\nseparations. Finally, we discuss the achievable performance within the current\nvdW-DF framework, the flexibility in functional design offered by vdW-DF3, as\nwell as possible future directions for non-local van der Waals density\nfunctional theory."
    },
    {
        "anchor": "Giant coercivity of dense nanostructured spark plasma sintered barium\n  hexaferrite: Due to the limited rare-earth elements resources, ferrite magnets need to be\nimproved drastically. Ideally, for a true hard magnet, the coercive field\nshould be larger than the saturation magnetization, which is not yet realized\nfor ferrites. Thus, an alternative can be found in making very fine grain\nferrite magnets, but it is usually impossible to get small grains and dense\nmaterial together. In this paper, it is shown that the spark plasma sintering\nmethod is able to produce approximately 80% of dense material with crystallites\nsmaller than 100 nm. The as-prepared bulk sintered anisotropic magnets exhibits\ncoercive field of 0.5 T which is approximately 60% of the theoretical limit and\nonly a few percentage below that of loose nanopowders. As a result, the magnets\nbehave nearly ideal (-1.18 slope in the BH plane second quadrant) and the\nenergy product reaches 8.8 kJ m-3, the highest value achieved in the isotropic\nferrite magnet to our knowledge.",
        "positive": "Selective crystal growth of indium selenide compounds from saturated\n  solutions grown in a selenium vapor: Indium selenide compounds are promising materials for energy conversion,\nspintronic applications, and chemical sensing. However, it is difficult to grow\nstoichiometric indium selenide crystals due to the high equilibrium selenium\nvapor pressure and the complicated phase equilibrium system of indium selenide\ncompounds. In this paper, we apply a novel and convenient crystal growth\nmethod, in which the saturated solution is grown by the application of a\nselenium vapor. In this method, selenium vapor at a pressure higher than the\nsaturated vapor pressure is applied to molten indium, such that the selenium\ncontinuously dissolves into the indium solution until the solubility at the\ngrowth temperature is reached; then a slow cooling process results in\ncrystallization. The selenium dose is matched to its solubility so that indium\nselenide compounds can be selectively grown just by controlling the temperature\nwithout the need to consider the chemical ratio in the solution. The pressure\nof the vapor is controlled during the whole growth process so that any\ndeviation from a stoichiometric composition in the crystal can be controlled.\nBoth InSe and In2Se3 were successfully grown using this method, and we have\ninvestigated the growth mechanism and found the growth window for each\ncompound. This study presents a novel and convenient approach to fabricating\ntransitional metal chalcogenides without deficiencies in the chalcogen element."
    },
    {
        "anchor": "Prediction of Novel Stable 2D-Silicon with Fivefold Coordination: Silicene, an analogue of graphene, was so far predicted to be the only\ntwo-dimensional silicon (2D-Si) with massless Dirac fermions. Here we predict a\nbrand new 2D-Si Dirac semimetal, which we name siliconeet [silik'ni:t].\nUnexpectedly, it has a much lower energy than silicene and robust\ndirection-dependent Dirac cones with Fermi velocities comparable to those in\ngraphene. Remarkably, its peculiar structure based on pentagonal rings and\nfivefold coordination plays a critical role in the novel electronic properties.\nTaking spin-orbit coupling into account, siliconeet can also be recognized as a\n2D-topological insulator with a larger nontrivial band gap than silicene.",
        "positive": "Entanglement and manipulation of the magnetic and spin-orbit order in\n  multiferroic Rashba semiconductors: The interplay between electronic eigenstates, spin, and orbital degrees of\nfreedom, combined with fundamental breaking of symmetries is currently one of\nthe most exciting fields of research. Multiferroics such as (GeMn)Te fulfill\nthese requirements providing unusual physical properties due to the coexistence\nand coupling between ferromagnetic and ferroelectric order in one and the same\nsystem. Here we show that multiferroic (GeMn)Te inherits from its parent\nferroelectric {\\alpha}-GeTe compound a giant Rashba splitting of\nthree-dimensional bulk states which competes with the Zeeman spin splitting\ninduced by the magnetic exchange interactions. The collinear alignment of\nferroelectric and ferromagnetic polarization leads to an opening of a tunable\nZeeman gap of up to 100 meV around the Dirac point of the Rashba bands, coupled\nwith a change in spin texture by entanglement of magnetic and spin-orbit order.\nThrough applications of magnetic fields, we demonstrate manipulation of spin-\ntexture by spin resolved photoemission experiments, which is also expected for\nelectric fields based on the multiferroic coupling. The control of spin\nhelicity of the bands and its locking to ferromagnetic and ferroelectric order\nopens fascinating new avenues for highly multifunctional multiferroic Rashba\ndevices suited for reprogrammable logic and/or nonvolatile memory applications."
    },
    {
        "anchor": "Thermoelectric transport properties of CaMg2Bi2, EuMg2Bi2, and YbMg2Bi2: The thermoelectric transport properties of CaMg2Bi2, EuMg2Bi2, and YbMg2Bi2\nwere characterized between 2 and 650K. As synthesized, the polycrystalline\nsamples are found to have lower p-type carrier concentrations than\nsingle-crystalline samples of the same empirical formula. These low carrier\nconcentration samples possess the highest mobilities yet reported for materials\nwith the CaAl2Si2 structure type, with a mobility of ~740cm$^2$/V/s observed in\nEuMg2Bi2 at 50K. Despite decreases in the Seebeck coefficient (\\alpha) and\nelectrical resistivity (\\rho) with increasing temperature, the power factor\n(\\alpha^2/\\rho) increases for all temperatures examined. This behavior suggests\na strong asymmetry in the conduction of electrons and holes. The highest figure\nof merit (zT) is observed in YbMg2Bi2, with zT approaching 0.4 at 600K for two\nsamples with carrier densities of approximately 2x10^{18}cm^{-3} and\n8x10^{18}cm^{-3} at room temperature. Refinements of neutron powder diffraction\ndata yield similar behavior for the structures of CaMg2Bi2 and YbMg2Bi2, with\nsmooth lattice expansion and relative expansion in $c$ being ~35% larger than\nrelative expansion in $a$ at 973K. First principles calculations reveal an\nincreasing band gap as Bi is replaced by Sb then As, and subsequent Boltzmann\ntransport calculations predict an increase in \\alpha for a given $n$ associated\nwith an increased effective mass as the gap opens. The magnitude and\ntemperature dependence of \\alpha suggests higher zT is likely to be achieved at\nlarger carrier concentrations, roughly an order of magnitude higher than those\nin the current polycrystalline samples, which is also expected from the\ndetailed calculations.",
        "positive": "Steady-state fracture toughness of elastic-plastic solids: Isotropic\n  versus kinematic hardening: The fracture toughness for a mode I/II crack propagating in a ductile\nmaterial has been subject to numerous investigations. However, the influence of\nthe material hardening law has received very limited attention, with isotropic\nhardening being the default choice if cyclic loads are absent. The present work\nextends the existing studies of monotonic mode I/II steady-state crack\npropagation with the goal to compare the predictions from an isotropic\nhardening model with that of a kinematic hardening model. The work is conducted\nthrough a purpose-built steady-state framework that directly delivers the\nsteady-state solution. In order to provide a fracture criterion, a cohesive\nzone model is adopted and embedded at the crack tip in the steady-state\nframework, while a control algorithm for the far-field, that significantly\nreduces the number of equilibrium iterations is employed to couple the\nfar-field loading to the correct crack tip opening. Results show that the\nsteady-state fracture toughness (shielding ratio) obtained for a kinematic\nhardening material is larger than for the corresponding isotropic hardening\ncase. The difference between the isotropic and kinematic model is tied to the\nnonproportional loading conditions and reverse plasticity. This also explains\nthe vanishing difference in the shielding ratio when considering mode II crack\npropagation as the non-proportional loading is less pronounced and the reverse\nplasticity is absent."
    },
    {
        "anchor": "Vibrational signatures for the identification of single-photon emitters\n  in hexagonal boron nitride: Color centers in h-BN are among the brightest emission centers known yet the\norigins of these emission centers are not well understood. Here, using\nfirst-principles calculations in combination with the generating function\nmethod, we systematically elucidate the coupling of specific defects to the\nvibrational degrees of freedom. We show that the lineshape of many defects\nexhibits strong coupling to high frequency phonon modes and that\nC$_{\\text{N}}$, C$_{\\text{B}}$, C$_{\\text{B}}$-C$_{\\text{N}}$ dimer and\nV$_{\\text{B}}$ can be associated with experimental lineshapes. Our detailed\ntheoretical study serves as a guide to identify optically active defects in\nh-BN that can suit specific applications in photonic-based quantum\ntechnologies, such as single photon emitters, hybrid spin-photon interfaces, or\nspin-mechanics interfaces.",
        "positive": "The Impact of Local Strain Fields in Non-Collinear Antiferromagnetic\n  Films: Antiferromagnets hosting structural or magnetic order that breaks time\nreversal symmetry are of increasing interest for 'beyond von Neumann computing'\napplications because the topology of their band structure allows for intrinsic\nphysical properties, exploitable in integrated memory and logic function. One\nsuch group are the non-collinear antiferromagnets. Essential for domain\nmanipulation is the existence of small net moments found routinely when the\nmaterial is synthesised in thin film form and attributed to symmetry-breaking\ncaused by spin canting, either from the Dzyaloshinskii-Moriya interaction or\nfrom strain. Although the spin arrangement of these materials makes them highly\nsensitive to strain, there is little understanding about the influence of local\nstrain fields caused by lattice defects on global properties, such as\nmagnetisation and anomalous Hall effect. This premise is investigated by\nexamining non-collinear films that are either highly lattice mismatched or\nclosely matched to their substrate. In either case, edge dislocation networks\nare generated and for the former case these extend throughout the entire film\nthickness, creating large local strain fields. These strain fields allow for\nfinite intrinsic magnetisation in seemly structurally relaxed films and\ninfluence the antiferromagnetic domain state and the intrinsic anomalous Hall\neffect."
    },
    {
        "anchor": "Spin-order-dependent magneto-elastic coupling in two dimensional\n  antiferromagnetic MnPSe$_3$ observed through Raman spectroscopy: Layered antiferromagnetic materials have emerged as a novel subset of the\ntwo-dimensional family providing a highly accessible regime with prospects for\nlayer-number-dependent magnetism. Furthermore, transition metal phosphorous\ntrichalcogenides, MPX3 (M = transition metal; X = chalcogen) provide a platform\nfor investigating fundamental interactions between magnetic and lattice degrees\nof freedom providing new insights for developing fields of spintronics and\nmagnonics. Here, we use a combination of temperature dependent Raman\nspectroscopy and density functional theory to explore\nmagnetic-ordering-dependent interactions between the manganese spin degree of\nfreedom and lattice vibrations of the non-magnetic sub-lattice via a\nKramers-Anderson super-exchange pathway in both bulk, and few-layer, manganese\nphosphorous triselenide (MnPSe$_3$). We observe a nonlinear temperature\ndependent shift of phonon modes predominantly associated with the non-magnetic\nsub-lattice, revealing their non-trivial spin-phonon coupling below the\nN{\\'e}el temperature at 74 K, allowing us to extract mode-specific spin-phonon\ncoupling constants.",
        "positive": "Structural and electronic properties of Li intercalated graphene on\n  SiC(0001): We investigate the structural and electronic properties of Li-intercalated\nmonolayer graphene on SiC(0001) using combined angle-resolved photoemission\nspectroscopy and first-principles density functional theory. Li intercalates at\nroom temperature both at the interface between the buffer layer and SiC and\nbetween the two carbon layers. The graphene is strongly $n$-doped due to charge\ntransfer from the Li atoms and two $\\pi$-bands are visible at the\n$\\bar{K}$-point. After heating the sample to 300$^\\circ$C, these $\\pi$-bands\nbecome sharp and have a distinctly different dispersion to that of\nBernal-stacked bilayer graphene. We suggest that the Li atoms intercalate\nbetween the two carbon layers with an ordered structure, similar to that of\nbulk LiC$_6$. An AA-stacking of these two layers becomes energetically\nfavourable. The $\\pi$-bands around the $\\bar{K}$-point closely resemble the\ncalculated band structure of a C$_6$LiC$_6$ system, where the intercalated Li\natoms impose a super-potential on the graphene electronic structure that opens\npseudo-gaps at the Dirac points of the two $\\pi$-cones."
    },
    {
        "anchor": "Quasi-free-standing single-layer WS2 achieved by intercalation: Large-area and high-quality single-layer transition metal dichalcogenides can\nbe synthesized by epitaxial growth on single-crystal substrates. An important\nadvantage of this approach is that the interaction between the single-layer and\nthe substrate can be strong enough to enforce a single crystalline orientation\nof the layer. On the other hand, the same interaction can lead to hybridization\neffects, resulting in the deterioration of the single-layer's native\nproperties. This dilemma can potentially be solved by decoupling the\nsingle-layer from the substrate surface after the growth via intercalation of\natoms or molecules. Here we show that such a decoupling can indeed be achieved\nfor single-layer WS2 epitaxially grown on Ag(111) by intercalation of Bi atoms.\nThis process leads to a suppression of the single-layer WS2-Ag substrate\ninteraction, yielding an electronic band structure reminiscent of free-standing\nsingle-layer WS2.",
        "positive": "structural and optical properties of InxGa1-xN/GaN epilayers grown on a\n  miscut sapphire substrate: We report on structural and optical properties of InGaN/GaN thin films, with\na 0.46o misalignment between the surface and the (0001) plane, which were grown\nby metal-organic chemical vapor deposition (MOCVD) on 0.34o miscut sapphire\nsubstrates. X-ray diffraction and X-ray reflectivity were used to precisely\nmeasure the degree of miscut. Reciprocal space mapping was employed to\ndetermine the lattice parameters and strain state of the InGaN layers.\nRutherford backscattering spectrometry with channeling was employed to measure\ntheir composition and crystalline quality with depth resolution. No strain\nanisotropy was observed. Polarization-dependent photoluminescence spectroscopy\nwas carried out to examine the effect of the miscut on the bandedge emission of\nthe epilayer."
    },
    {
        "anchor": "Fermi surface of yttrium: Electron-positron momentum densities in Y, reconstructed from two-dimensional\nangular correlation of annihilation radiation spectra, are compared with the\ntheoretical predictions of fully-relativistic augmented plane-wave\ncalculations. Knowledge of the theoretical densities and of the effects on them\nof certain symmetry selection rules has allowed us to separate two hole Fermi\nsur-faces in the third and fourth bands and to establish some Fermi momenta for\neach of them.",
        "positive": "Large zero-field cooled exchange-bias in bulk Mn2PtGa: We report a large exchange-bias (EB) effect after zero-field cooling the new\ntetragonal Heusler compound Mn2PtGa from the paramagnetic state. The\nfirst-principle calculation and the magnetic measurements reveal that Mn2PtGa\norders ferrimagnetically with some ferromagnetic (FM) inclusions. We show that\nferrimagnetic (FI) ordering is essential to isothermally induce the exchange\nanisotropy needed for the zero-field cooled (ZFC) EB during the virgin\nmagnetization process. The complex magnetic behavior at low temperatures is\ncharacterized by the coexistence of a field induced irreversible magnetic\nbehavior and a spin-glass-like phase. The field induced irreversibility\noriginates from an unusual first-order FI to antiferromagnetic transition,\nwhereas, the spin-glass like state forms due to the existence of anti-site\ndisorder intrinsic to the material."
    },
    {
        "anchor": "High-Temperature Superconductivity in the Ti--H System at High Pressures: Search for stable high-pressure compounds in the Ti--H system reveals the\nexistence of titanium hydrides with new stoichiometries, including\nIbam-Ti$_2$H$_5$, I4/m-Ti$_5$H$_{13}$, I$\\bar{4}$-Ti$_5$H$_{14}$, Fddd-TiH$_4$,\nImmm-Ti$_2$H$_{13}$, P$\\bar{1}$-TiH$_{12}$, and C2/m-TiH$_{22}$. Our\ncalculations predict I4/mmm $\\rightarrow$ R$\\bar{3}$m and I4/mmm $\\rightarrow$\nCmma transitions in TiH and TiH$_2$, respectively. Phonons and the\nelectron--phonon coupling of all searched titanium hydrides are analyzed at\nhigh pressure. It is found that Immm-Ti$_2$H$_{13}$ rather than the highest\nhydrogen content C2/m-TiH$_{22}$, exhibits the highest superconducting critical\ntemperature T$_{c}$. The estimated T$_{c}$ of Immm-Ti$_2$H$_{13}$ and\nC2/m-TiH$_{22}$ are respectively 127.4--149.4 K ($\\mu^{*}$=0.1-0.15) at 350 GPa\nand 91.3--110.2 K at 250 GPa by numerically solving the Eliashberg equations.\nOne of the effects of pressure on T$_{c}$ can be attributed to the softening\nand hardening of phonons with increasing pressure.",
        "positive": "Proximity Effect Induced Electronic Properties of Epitaxial Graphene on\n  Bi2Te2Se: We report that the {\\pi}-electrons of graphene can be spin-polarized to\ncreate a phase with a significant spin-orbit gap at the Dirac point (DP) using\na graphene-interfaced topological insulator hybrid material. We have grown\nepitaxial Bi2Te2Se (BTS) films on a chemical vapor deposition (CVD) graphene.\nWe observe two linear surface bands both from the CVD graphene notably\nflattened and BTS coexisting with their DPs separated by 0.53 eV in the\nphotoemission data measured with synchrotron photons. We further demonstrate\nthat the separation between the two DPs, {\\Delta}D-D, can be artificially\nfine-tuned by adjusting the amount of Cs atoms adsorbed on the graphene to a\nvalue as small as {\\Delta}D-D = 0.12 eV to find any proximity effect induced by\nthe DPs. Our density functional theory calculation shows a spin-orbit gap of\n~20 meV in the {\\pi}-band enhanced by three orders of magnitude from that of a\npristine graphene, and a concomitant phase transition from a semi-metallic to a\nquantum spin Hall phase when {\\Delta}D-D $\\leq$ 0.20 eV. We thus present a\npractical means of spin-polarizing the {\\pi}-band of graphene, which can be\npivotal to advance the graphene-based spintronics."
    },
    {
        "anchor": "Symmetry, distorted bandstructure, and spin-orbit coupling of\n  (group-III) metal-monochalcogenide monolayers: The electronic structure of (group-III) metal-monochalcogenide monolayers\nexhibits many unusual features. Some, such as the unusually distorted upper\nvalence band dispersion we describe as a 'caldera', are primarily the result of\npurely orbital interactions. Others, including spin splitting and wavefunction\nspin-mixing, are directly driven by spin-orbit coupling. We employ elementary\ngroup theory to explain the origins of these properties, and use a\ntight-binding model to calculate the phenomena enabled by them, such as\nband-edge carrier effective g-factors, optical absorption spectrum, conduction\nelectron spin orientation, and a relaxation-induced upper valence band\npopulation inversion and spin polarization mechanism.",
        "positive": "Tunneling Field-Effect Junctions with WS$_2$ barrier: Transition metal dichalcogenides (TMDCs), with their two-dimensional\nstructures and sizable bandgaps, are good candidates for barrier materials in\ntunneling field-effect transistor (TFET) formed from atomic precision vertical\nstacks of graphene and insulating crystals of a few atomic layers in thickness.\nWe report first-principles study of the electronic properties of the\nGraphene/WS$_2$/Graphene sandwich structure revealing strong interface effects\non dielectric properties and predicting a high ON/OFF ratio with an appropriate\nWS$_2$ thickness and a suitable range of the gate voltage. Both the band\nspin-orbit coupling splitting and the dielectric constant of the WS$_2$ layer\ndepend on its thickness when in contact with the graphene electrodes,\nindicating strong influence from graphene across the interfaces. The dielectric\nconstant is significantly reduced from the bulk WS$_2$ value. The effective\nbarrier height varies with WS$_2$ thickness and can be tuned by a gate voltage.\nThese results are critical for future nanoelectronic device designs."
    },
    {
        "anchor": "Nanoscale structure and mechanism for enhanced electromechanical\n  response of highly-strained BiFeO3 thin films: The nanostructural evolution of the strain-induced structural phase\ntransition in BiFeO3 is examined. Using high-resolution X-ray diffraction and\nscanning-probe microscopy-based studies we have uniquely identified and\nexamined the numerous phases present at these phase boundaries and have\ndiscovered an intermediate monoclinic phase in addition to the previously\nobserved rhombohedral- and tetragonal-like phases. Further analysis has\ndetermined that the so-called mixed-phase regions of these films are not\nmixtures of rhombohedral- and tetragonal-like phases, but intimate mixtures of\nhighly-distorted monoclinic phases with no evidence for the presence of the\nrhombohedral-like parent phase. Finally, we propose a mechanism for the\nenhanced electromechanical response in these films including how these phases\ninteract at the nanoscale to produce large surface strains.",
        "positive": "Efficient thermoelectricity in Sr$_2$Nb$_2$O$_7$ with energy-dependent\n  relaxation times: We evaluate theoretically the thermoelectric efficiency of the layered\nperovskite Sr$_2$Nb$_2$O$_7$ via calculations of the electronic structure and\ntransport coefficients within density-functional theory and Bloch-Boltzmann\nrelaxation-time transport theory. The predicted figure-of-merit tensor $ZT$,\ncomputed with energy-, chemical potential- and temperature-dependent relaxation\ntimes, has one component increasing monotonically from around 0.4 at room\ntemperature to 2.4 at 1250 K at an optimal carrier density around\n2$\\times$10$^{20}$ cm$^{-3}$, while the other components are small. The Seebeck\ncoefficient is about 250 to 300 $\\mu$V/K at optimal doping, and reaches 800\n$\\mu$V/K at lower doping. We provide a {\\tt python} code implementing various\napproximations to the energy-dependent relaxation time transport, which can be\nused to address different systems with an appropriate choice of material\nparameters."
    },
    {
        "anchor": "Hard Simulation Problems in the Modeling of Magnetic Materials:\n  Parallelization and Langevin Micromagnetics: We present recent results on two attempts at understanding and utilizing\nlarge-scale simulations of magnetic materials. In the first study we consider\nmassively parallel implementations on a Cray T3E of the n-fold way algorithm\nfor magnetization switching in kinetic Ising models. We find an intricate\nrelationship between the average time increment and the size of the spin blocks\non each processor. This narrows the regime of efficient implementation. The\nsecond study concerns incorporating noise into micromagnetic calculations using\nLangevin methods. This allows measurement of quantities such as the probability\nthat the system has not switched within a given time. Preliminary results are\nreported for arrays of single-domain nanoscale pillars.",
        "positive": "Electron-Hole Asymmetry of Surface States in Topological Insulator\n  Sb2Te3 Thin Films Revealed by Magneto-Infrared Spectroscopy: When surface states (SSs) form in topological insulators (TIs), they inherit\nthe properties of bulk bands, including the electron-hole (e-h) asymmetry but\nwith much more profound impacts. Here, via combining magneto-infrared\nspectroscopy with theoretical analysis, we show that e-h asymmetry\nsignificantly modifies the SS electronic structures when interplaying with the\nquantum confinement effect. Compared to the case without e-h asymmetry, the SSs\nnow bear not only a band asymmetry as that in the bulk but also a shift of the\nDirac point relative to the bulk bands and a reduction of the hybridization gap\nup to 70%. Our results signify the importance of e-h asymmetry in band\nengineering of TIs in the thin film limit."
    },
    {
        "anchor": "Assembling Di- and Multiatomic Si Clusters in Graphene via Electron Beam\n  Manipulation: We demonstrate assembly of di-, tri- and tetrameric Si clusters on the\ngraphene surface using sub-atomically focused electron beam of a scanning\ntransmission electron microscope. Here, an electron beam is used to introduce\nSi substitutional defects and defect clusters in graphene with spatial control\nof a few nanometers, and enable controlled motion of Si atoms. The Si\nsubstitutional defects are then further manipulated to form dimers, trimers and\nmore complex structures. The dynamics of a beam induced atomic scale chemical\nprocess is captured in a time-series of images at atomic resolution. These\nstudies suggest that control of the e-beam induced local processes offers the\nnext step toward atom-by-atom nanofabrication and provides an enabling tool for\nstudy of atomic scale chemistry in 2D materials.",
        "positive": "Interacting many-body systems in quantum wells: Evidence for\n  exciton-trion-electron correlations: We report on the nonlinear optical dynamical properties of excitonic\ncomplexes in CdTe modulation-doped quantum wells, due to many-body interactions\namong excitons, trions and electrons. These were studied by time and spectrally\nresolved pump-probe experiments. The results reveal that the nonlinearities\ninduced by trions differ from those induced by excitons, and in addition they\nare mutually correlated. We propose that the main source of these subtle\ndifferences comes from the Pauli exclusion-principle through phase-space\nfilling and short-range fermion exchange."
    },
    {
        "anchor": "Metallization of the \u03b2-SiC(100) 3\\times2 Surface: a DFT\n  Investigation: Using density functional theory (DFT) we report results for the electronic\nstructure and vibrational dynamics of hydrogenated {\\beta} reconstructed\nSilicon Carbide (001) (3x2) surfaces with various levels of hydrogenation.\nThese results were obtained using density functional theory with a generalized\ngradient exchange correlation function. The calculations reveal that\nmetallization can be achieved via hydrogen atoms occupying the second silicon\nlayer. Further increases of hydrogen occupation on the second silicon layer\nsites result in a loss of this metallization. For the former scenario, where\nmetallization occurs, we found a new vibrational mode at 1870 cm-1, which is\ndistinct from the mode associated with hydrogen atoms on the first layer.\nFurthermore, we found the diffusion barrier for a hydrogen atom to move from\nthe second to the third silicon layer to be 258 meV.",
        "positive": "Skyrmion-Excited Spin Wave Fractal Network: Magnetic skyrmions exhibit unique, technologically relevant pseudo-particle\nbehaviors which arise from their topological protection, including\nwell-defined, three-dimensional dynamic modes that occur at microwave\nfrequencies. During dynamic excitation, spin waves are ejected into the\ninterstitial regions between skyrmions, creating the magnetic equivalent of a\nturbulent sea. However, since the spin waves in these systems have a\nwell-defined length scale, and the skyrmions are on an ordered lattice, ordered\nstructures from spin wave interference can precipitate from the chaos. This\nwork uses small angle neutron scattering (SANS) to capture the dynamics in\nhybrid skyrmions and investigate the spin wave structure. Performing\nsimultaneous ferromagnetic resonance and SANS, the diffraction pattern shows a\nlarge increase in low-angle scattering intensity which is present only in the\nresonance condition. This scattering pattern is best fit using a mass fractal\nmodel, which suggests the spin waves form a long-range fractal network. The\nfractal structure is constructed of fundamental units with a size that encodes\nthe spin wave emissions and are constrained by the skyrmion lattice. These\nresults offer critical insights into the nanoscale dynamics of skyrmions,\nidentify a new dynamic spin wave fractal structure, and demonstrates SANS as a\nunique tool to probe high-speed dynamics."
    },
    {
        "anchor": "Bulk and surface electronic states in the dosed semimetallic\n  HfTe$\\boldsymbol{_2}$: The dosing of layered materials with alkali metals has become a commonly used\nstrategy in ARPES experiments. However, precisely what occurs under such\nconditions, both structurally and electronically, has remained a matter of\ndebate. Here we perform a systematic study of 1T-HfTe$_2$, a prototypical\nsemimetal of the transition metal dichalcogenide family. By utilizing photon\nenergy-dependent angle-resolved photoemission spectroscopy (ARPES), we have\ninvestigated the electronic structure of this material as a function of\nPotassium (K) deposition. From the k$_z$ maps, we observe the appearance of 2D\ndispersive bands after electron dosing, with an increasing sharpness of the\nbands, consistent with the wavefunction confinement at the topmost layer. In\nour highest-dosing cases, a monolayer-like electronic structure emerges,\npresumably as a result of intercalation of the alkali metal. Here, by bringing\nthe topmost valence band below $E_F$, we can directly measure a band overlap of\n$\\sim$ 0.2 eV. However, 3D bulk-like states still contribute to the spectra\neven after considerable dosing. Our work provides a reference point for the\nincreasingly popular studies of the alkali metal dosing of semimetals using\nARPES.",
        "positive": "Exploring Magnetism of Lead-free Halide Double Perovskites: A\n  High-Throughput First-Principles Study: We have performed a comprehensive, first-principles high-throughput study of\nthe magnetic properties of halide double perovskites, $Cs_2BB^\\prime Cl_6$,\nwith magnetic ions occupying one or both B and B$^\\prime$ sites. Our findings\nindicate a general tendency for these materials to exhibit antiferromagnetic\nordering with low N\\'eel temperatures. At the same time, we reveal a few\npotential candidates that predicted to be ferromagnetic with relatively high\nCurie temperatures. Achieving ferromagnetic coupling might be feasible via\nsimultaneously alloying at B and B$^\\prime$ sites with magnetic 3d and\nnon-magnetic 5d ions. With this approach, we discover that $Cs_2HgCrCl_6$,\n$Cs_2AgNiCl_6$ and $Cs_2AuNiCl_6$ have high Curie temperatures relative to\ntheir peers, with the latter two exhibiting half metallic behaviour. Further,\nthis study illuminates the underpinning mechanism of magnetic exchange\ninteractions in halide double perovskites, enabling a deeper understanding of\ntheir magnetic behaviour. Our findings, especially the discovery of the\ncompounds with robust half-metallic properties and high Curie temperatures\nholds promise for potential applications in the field of spintronics."
    },
    {
        "anchor": "Magnetism Controlled Vortex Matter: We discuss a new class of phenomena based on strong interaction between\nmagnetic superstructures and vortices in superconductors in combined\nheterogeneous structures. An inhomogeneous magnetization can pin vortices or\ncreate them spontaneously changing drastically properties of the\nsuperconductor. On the other hand, the interaction between magnetic moments\nmediated by vortices can result in specific types of magnetic ordering. The\nsame interaction can create coupled magnetic-superconducting defects. We\ndiscuss possible experimental observation of magnetism controlled vortex matter\nin superconducting films with magnetic nanoscale dots or stripes and layered\nsystems with alternating superconducting and magnetic layers.",
        "positive": "Molecular Dynamics and OKMC Study of Radiation Induced Motion of Voids\n  and He Bubbles in BCC Iron: We show that voids adjacent to radiation damage cascades can be moved in\ntheir entirety by several lattice spacings. This is done using molecular\ndynamics cascade simulations in iron at energies of 1-5 keV. The effect of this\nmechanism is studied further using an OKMC code and shows enhancement of void\ndiffusion by 2 orders of magnitude from 1x10^-22 cm^2/s to 3x10^-20 cm^2/s.\nRepeating the study on He bubbles shows that the movement is damped by the\npresence of helium in the void."
    },
    {
        "anchor": "On the Effect of Nucleation Undercooling on Phase Transformation\n  Kinetics: We carry out an extensive comparison between Johnson-Mehl-Avrami-Kolmogorov\n(JMAK) theory of first-order phase transformation kinetics and phase-field (PF)\nresults of a benchmark problem on nucleation. To address the stochasticity of\nthe problem, several hundreds of simulations are performed to establish a\ncomprehensive, statistically-significant analysis of the coincidences and\ndiscrepancies between PF and JMAK transformation kinetics. We find that PF\npredictions are in excellent agreement with both classical nucleation theory\nand JMAK theory, as long as the original assumptions of the latter are\nappropriately reproduced - in particular, the constant nucleation and growth\nrates in an infinite domain. When deviating from these assumptions, PF results\nare at odds with JMAK theory. In particular, we observe that the size of the\ninitial particle radius $r_0$ relative to the critical nucleation radius $r^*$\nhas a significant effect on the rate of transformation. While PF and JMAK agree\nwhen $r_0$ is sufficiently higher than $r^*$, the duration of initial transient\ngrowth stage of a particle, before it reaches a steady growth velocity,\nincreases as $r_0/r^*\\to 1$. This incubation time has a significant effect on\nthe overall kinetics, e.g. on the Avrami exponent of the multi-particle\nsimulations. In contrast, for the considered conditions and parameters, the\neffect of interface curvature upon transformation kinetics - in particular\nnegative curvature regions appearing during particle impingement, present in PF\nbut absent in JMAK theory - appears to be minor compared to that of $r_0/r^*$.\nWe argue that rigorous benchmarking of phase-field models of stochastic\nprocesses (e.g. nucleation) need sufficient statistical data in order to make\nrigorous comparisons against ground truth theories. In these problems, analysis\nof probability distributions is clearly preferable to a deterministic approach.",
        "positive": "Broadband black phosphorus optical modulator in visible to mid-infrared\n  spectral range: Black phosphorous (BP), a two-dimensional (2D) material, has a direct\nbandgap, which fills up the bandgap lacuna left by graphene topological\ninsulators and transition-metal dichalcogenides because of its dependence on\nthe layers and applied strains. Theoretically, the direct and tunable band gap\nindicates the broadband applications in optoelectronics with high efficiencies\nin the spectral range from visible to mid-infrared. Here, a BP broadband\noptical modulator is experimentally constructed and the passively modulated\nlasers at 639 nm (red), 1.06 um (near-infrared) and 2.1 um (mid-infrared) are\nrealized by using the BP optical modulator as the saturable absorber in bulk\nlasers. The obtained results provide a promising alternative for rare broadband\noptical modulators and broaden the application range of BP in photonics."
    },
    {
        "anchor": "Observation of Coherently Coupled Cation Spin Dynamics in an Insulating\n  Ferrimagnetic Oxide: Many technologically useful magnetic oxides are ferrimagnetic insulators,\nwhich consist of chemically distinct cations. Here, we examine the spin\ndynamics of different magnetic cations in ferrimagnetic NiZnAl-ferrite\n(Ni$_{0.65}$Zn$_{0.35}$Al$_{0.8}$Fe$_{1.2}$O$_4$) under continuous microwave\nexcitation. Specifically, we employ time-resolved x-ray ferromagnetic resonance\nto separately probe Fe$^{2+/3+}$ and Ni$^{2+}$ cations on different sublattice\nsites. Our results show that the precessing cation moments retain a rigid,\ncollinear configuration to within $\\approx$2$^\\circ$. Moreover, the effective\nspin relaxation is identical to within $<$10% for all magnetic cations in the\nferrite. We thus validate the oft-assumed ``ferromagnetic-like'' dynamics in\nresonantly driven ferrimagnetic oxides, where the magnetic moments from\ndifferent cations precess as a coherent, collective magnetization.",
        "positive": "Radiation resistance of fine-grained ceramics Y2.5Nd0.5Al5O12 under\n  Xe-ions irradiation: Oxide Y2.5Nd0.5Al5O12 (YAG:Nd) with garnet structure was synthesized in the\npowder and ceramics forms. Fine-grained YAG:Nd ceramics with a relative density\nof ~99% were obtained by the Spark Plasma Sintering method (SPS). The radiation\nresistance of ceramics was studied under irradiation with swift Xe-ions (E =\n146 MeV). A gradient defect structure is formed in irradiated ceramics, varying\nfrom layer to layer. The strained YAG phase formed as a result of Xe ions\nirradiation is localized in a near-surface layer with a thickness of ~5 {\\mu}m.\nFull amorphization of the samples was observed under irradiation with a fluence\nof 1x10^13 cm-2. The calculated critical fluence was 6.5x10^12 cm-2, which\ncorresponded to 0.03 dpa. The microhardness of the surface layers of irradiated\nceramics is less than the central layers, and, in general, decreases with\nincreasing ion fluence."
    },
    {
        "anchor": "Sensitiveness of the ratio between monovacancy and bulk positron\n  lifetimes to the approximations used in the calculations: Periodic behaviour: Positron lifetimes have been calculated in bulk and monovacancies for most of\nthe elements of the periodic table. Self-consistent and non-self-consistent\nschemes have been used for the calculation of the electronic structure in the\nsolid, as well as different parameterizations for the positron enhancement\nfactor and correlation energy. The ratio between the monovacancy and bulk\nlifetimes has been analyzed. This ratio shows a periodic behaviour with atomic\nnumber in all the calculation methods and it is in agreement with selected\nexperimental data. The ratio shows, in contradiction to previous assumptions,\nsensitiveness to the approximations used in the calculations. This extensive\nwork has allowed us to study and enlighten features of the theory and computing\nmethods broadly used nowadays in simulating, studying and understanding\npositronic parameters.",
        "positive": "Preparation of hierarchical C@MoS2@C sandwiched hollow spheres for\n  Lithium ion batteries: Hierarchical C@MoS2@C hollow spheres with the active MoS2 nanosheets being\nsandwiched by carbon layers have been produced by means of a modified template\nmethod. The process applies polydopamine (PDA) layers which inhibit morphology\nchange of the template thereby enforcing the hollow microsphere structure. In\naddition, PDA forms complexes with the Mo precursor, leading to an in-situ\ngrowth of MoS2 on its surface and preventing the nanosheets from agglomeration.\nIt also supplies the carbon that finally sandwiches the 100-150 nm thin MoS2\nspheres. The resulting hierarchically structured material provides a stable\nmicrostructure where carbon layers strongly linked to MoS2 offer efficient\npathways for electron and ion transfer, and concomitantly buffer the volume\nchanges inevitably appearing during the charge-discharge process.\nCarbon-sandwiched MoS2-based electrodes exhibit high specific capacity of\napproximately 900 mA h g-1 after 50 cycles at 0.1 C, excellent cycling\nstability up to 200 cycles, and superior rate performance. The versatile\nsynthesis method reported here offers a general route to design hollow sandwich\nstructures with a variety of different active materials."
    },
    {
        "anchor": "Universal Scaling in Mixing Correlated Growth with Randomness: We study two-component growth that mixes random deposition (RD) with a\ncorrelated growth process that occurs with probability p. We find that these\ncomposite systems are in the universality class of the correlated growth\nprocess. For RD blends with either Edwards-Wilkinson of Kardar-Parisi-Zhang\nprocesses, we identify a nonuniversal parameter in the universal scaling in p.",
        "positive": "Controlling magnon-photon coupling in a planar geometry: The tunability of magnons enables their interaction with various other\nquantum excitations, including photons, paving the route for novel hybrid\nquantum systems. Here, we study magnon-photon coupling using a high-quality\nfactor split-ring resonator and single-crystal yttrium iron garnet (YIG)\nspheres at room temperature. We investigate the dependence of the coupling\nstrength on the size of the sphere and find that the coupling is stronger for\nspheres with a larger diameter as predicted by theory. Furthermore, we\ndemonstrate strong magnon-photon coupling by varying the position of the YIG\nsphere within the resonator. Our experimental results reveal the expected\ncorrelation between the coupling strength and the rf magnetic field. These\nfindings demonstrate the control of coherent magnon-photon coupling through the\ntheoretically predicted square-root dependence on the spin density in the\nferromagnetic medium and the magnetic dipolar interaction in a planar\nresonator."
    },
    {
        "anchor": "Magnetic order of tetragonal CuO ultra-thin films: We present a detailed low-energy muon spin rotation and x-ray magnetic\ncircular dichroism (XMCD) investigation of the magnetic structure in ultra-thin\ntetragonal (T)-CuO films. The measured muon-spin polarization decay indicates\nan antiferromagnetic (AFM) order with a transition temperature higher than\n200K. The XMCD signal obtained around the Cu $L_{2,3}$ edges indicates the\npresence of pinned Cu$^{2+}$ moments that are parallel to the sample surface,\nand additionally, isotropic paramagnetic moments. The pinning of some of the Cu\nmoments is caused by an AFM ordering consisting of moments that lie most likely\nin the plane of the film. Moreover, pinned moments show a larger orbital\nmagnetic moment contribution with an approximate ratio of $m_{orb}/m_{spin} =\n2$, indicating that these spins are located at sites with reduced symmetry.\nSome fractions of the pinned moments remain pinned from an AFM background even\nat 360K, indicating that $T_N >$ 360K. A simple model could explain\nqualitatively these experimental findings; however, it is in contrast to\ntheoretical predictions, showing that the magnetic properties of ultra-thin\nT-CuO films differ from bulk expectations and is more complex.",
        "positive": "Informatics-based learning of oxygen vacancy ordering principles in\n  oxygen-deficient perovskites: Ordered oxygen vacancies (OOVs) in perovskites can exhibit long-range order\nand may be used to direct materials properties through modifications in\nelectronic structures and broken symmetries. Based on the various vacancy\npatterns observed in previously known compounds, we explore the ordering\nprinciples of OOVs in oxygen-deficient perovskite oxides with\n$AB\\mathrm{O}_{2.5}$ stoichiometry to identify other OOV variants. We performed\nfirst-principles calculations to assess the OOV stability on a dataset of 50\nOOV structures generated from our bespoke algorithm. The algorithm employs\nuniform planar vacancy patterns on (111) pseudocubic perovskite layers and the\napproach proves effective for generating stable OOV patterns with minimal\ncomputational loads. We find as expected that the major factors determining the\nstability of OOV structures include coordination preferences of transition\nmetals and elastic penalties resulting from the assemblies of polyhedra.\nCooperative rotational modes of polyhedra within OOV structures reduce elastic\ninstabilities by optimizing the bond valence of $A$- and $B$-cations. This\nfinding explains the observed formation of vacancy channels along low-index\ncrystallographic directions in prototypical OOV phases. The identified ordering\nprinciples enable us to devise other stable vacancy patterns with longer\nperiodicity for targeted property design in yet to be synthesized compounds."
    },
    {
        "anchor": "Polarization Rotation, Switching and E-T phase diagrams of BaTiO$_3$: A\n  Molecular Dynamics Study: We use molecular dynamics simulations to understand the mechanisms of\npolarization switching in ferroelectric BaTiO$_3$ achieved with external\nelectric field. For tetragonal and orthorhombic ferroelectric phases, we\ndetermine the switching paths, and show that polarization rotation through\nintermediate monoclinic phases (a) facilitates switching at low fields (b) is\nresponsible for a sharp anisotropy in polarization switching. We develop\nunderstanding of this through determination of detailed electric\nfield-temperature phase diagrams, that are fundamental to technological\napplications based on electromechanical and switching response of\nferroelectrics.",
        "positive": "Ultra-fast perpendicular Spin Orbit Torque MRAM: We demonstrate ultra-fast (down to 400 ps) bipolar magnetization switching of\na three-terminal perpendicular Ta/FeCoB/MgO/FeCoB magnetic tunnel junction. The\ncritical current density rises significantly as the current pulse shortens\nbelow 10 ns, which translates into a minimum in the write energy in the ns\nrange. Our results show that SOT-MRAM allows fast and low power write\noperations, which renders it promising for non-volatile cache memory\napplications."
    },
    {
        "anchor": "Origin of the Non-Linear Pressure Effects in Perovskite Manganites:\n  Buckling of Mn-O-Mn Bonds and Jahn-Teller Distortion of the MnO6 Octahedra\n  Induced by Pressure: High-pressure resistivity and x-ray diffraction have been measured on\nLa0.85MnO3-d. At low pressures the metal-insulator transition temperature (TMI)\nincreases linearly with pressure up to a critical pressure, P* ~ 3.4 GPa, which\nis followed by reduction of TMI with increasing pressure. Analysis of the bond\ndistances and bond angles reveal that a bandwidth increase drives the in-crease\nof TMI for pressure below P*. The reduction of TMI at higher pressures is found\nto result from Jahn-Teller distortions of the MnO6 octahedra. The role of\nanharmonic interatomic potential is discussed.",
        "positive": "3D-to-2D Transition of Anion Mobility in CsPbBr$_{3}$ under Pressure: We study the effects of hydrostatic pressure in the range 0.0--2.0 GPa on\nanion mobility in the orthorhombic $Pnma$ phase of CsPbBr$_{3}$. Using density\nfunctional theory and the climbing nudged elastic band method, we calculate the\ntransition states and activation energies for anions to migrate both within and\nbetween neighbouring PbBr$_{3}$ octahedra. The results of those calculations\nare used as input to a kinetic model for anion migration, which we solve in the\nsteady state to determine the anion mobility tensor as a function of applied\npressure. We find that the response of the mobility tensor to increasing\npressure is highly anisotropic, being strongly enhanced in the $(010)$ lattice\nplane and strongly reduced in the direction normal to it at elevated pressure.\nThese results demonstrate the potentially significant influence of pressure and\nstrain on the magnitude and direction of anion migration in lead--halide\nperovskites."
    },
    {
        "anchor": "Electron propagation from a photo-excited surface: implications for\n  time-resolved photoemission: We perform time- and angle-resolved photoelectron spectroscopy on p-type\nGaAs(110). We observe an optically excited population in the conduction band,\nfrom which the time scales of intraband relaxation and surface photovoltage\ndecay are both extracted. Moreover, the photovoltage shift of the valence band\nintriguingly persists for hundreds of picoseconds at negative delays. By\ncomparing to a recent theoretical study, we reveal that the negative-delay\ndynamics reflects the interaction of the photoelectrons with a\nphotovoltage-induced electric field outside the sample surface. We develop a\nconceptual framework to disentangle the intrinsic electron dynamics from this\nlong-range field effect, which sets the foundation for understanding\ntime-resolved photoemission experiments on a broad range of materials in which\npoor electronic screening leads to surface photovoltage. Finally, we\ndemonstrate how the long-lasting negative-delay dynamics in GaAs can be\nutilized to conveniently establish the temporal overlap of pump and probe\npulses in a time-resolved photoemission setup.",
        "positive": "Strong Reduction of Thermal Conductivity of WSe2 with Introduction of\n  Atomic Defects: The thermal conductivities of pristine and defective tungsten diselenide\n(WSe2) are investigated by using equilibrium molecular dynamics method. The\nthermal conductivity of WSe2 increases dramatically with size below a\ncharacteristic with of ~ 5 nm and levels off for broader samples and reaches a\nconstant value of ~2 W/mK. By introducing atomic vacancies, we discovered that\nthe thermal conductivity of WSe2 is significantly reduced. In particular, the W\nvacancy has a greater impact on thermal conductivity reduction than Se\nvacancies: the thermal conductivity of pristine WSe2 reduced by ~60% and ~70%\nwith the adding of ~1% of Se and W vacancies, respectively. The reduction of\nthermal conductivity is found to be related with the decrease of mean free path\n(MFP) of phonons in the defective WSe2. The MFP of WSe2 decreases from ~4.2 nm\nfor prefect WSe2 to ~2.2 nm with the adding of 0.9% Se vacancies. More\nsophisticated types of point defects, such as vacancy clusters and anti-site\ndefects, are explored in addition to single vacancies, and are found to\ndramatically renormalize the phonons. The reconstruction of the bonds leads to\nlocalized phonons in the forbidden gap in the phonon density of states which\nleads to the drop of thermal conduction. This work demonstrates the influence\nof different defects on thermal conductivity of single-layer WSe2, providing\ninsight into the process of defect-induced phonon transport as well as ways to\nimprove heat dissipation in WSe2-based electronic devices."
    },
    {
        "anchor": "Mechanical Properties and Fracture Patterns of Graphene (Graphitic)\n  Nanowiggles: Graphene nanowiggles (GNW) are graphene-based nanostructures obtained by\nmaking alternated regular cuts in pristine graphene nanoribbons. GNW were\nrecently synthesized and it was demonstrated that they exhibit tunable\nelectronic and magnetic properties by just varying their shape. Here, we have\ninvestigated the mechanical properties and fracture patterns of a large number\nof GNW of different shapes and sizes using fully atomistic reactive molecular\ndynamics simulations. Our results show that the GNW mechanical properties are\nstrongly dependent on its shape and size and, as a general trend narrow sheets\nhave larger ultimate strength and Young's modulus than wide ones. The estimated\nYoung's modulus values were found to be in a range of ~ 100-1000 GPa and the\nultimate strength in a range of ~ 20-110 GPa, depending on GNW shape. Also,\nsuper-ductile behaviour under strain was observed for some structures.",
        "positive": "Accelerating Defect Predictions in Semiconductors Using Graph Neural\n  Networks: Here, we develop a framework for the prediction and screening of native\ndefects and functional impurities in a chemical space of Group IV, III-V, and\nII-VI zinc blende (ZB) semiconductors, powered by crystal Graph-based Neural\nNetworks (GNNs) trained on high-throughput density functional theory (DFT)\ndata. Using an innovative approach of sampling partially optimized defect\nconfigurations from DFT calculations, we generate one of the largest\ncomputational defect datasets to date, containing many types of vacancies,\nself-interstitials, anti-site substitutions, impurity interstitials and\nsubstitutions, as well as some defect complexes. We applied three types of\nestablished GNN techniques, namely Crystal Graph Convolutional Neural Network\n(CGCNN), Materials Graph Network (MEGNET), and Atomistic Line Graph Neural\nNetwork (ALIGNN), to rigorously train models for predicting defect formation\nenergy (DFE) in multiple charge states and chemical potential conditions. We\nfind that ALIGNN yields the best DFE predictions with root mean square errors\naround 0.3 eV, which represents a prediction accuracy of 98 % given the range\nof values within the dataset, improving significantly on the state-of-the-art.\nModels are tested for different defect types as well as for defect charge\ntransition levels. We further show that GNN-based defective structure\noptimization can take us close to DFT-optimized geometries at a fraction of the\ncost of full DFT. DFT-GNN models enable prediction and screening across\nthousands of hypothetical defects based on both unoptimized and\npartially-optimized defective structures, helping identify electronically\nactive defects in technologically-important semiconductors."
    },
    {
        "anchor": "Phase decomposition in an Fe-Cr alloy at 402 deg C: M\u00f6ssbauer\n  spectroscopic study: Phase separation in strained and strain-free samples of Fe84.85Cr15.15\ninduced by an isothermal annealing at 402 deg C up to 3888 h was studied by\nmeans of the Mossbauer spectroscopy. The measured Fe-site spectra were analyzed\nwith two different procedures viz. a hyperfine field distribution and a\ntwo-shell superposition methods. Information relevant to the kinetics of the\nseparation process, concentration of Cr in Fe-rich phase, short-range ordering\nand magnetic texture was obtained based on values of spectral parameters. In\nparticular, the following quantities pertinent to the kinetics were found: the\nactivation energy, equal to 1666 kJ per mol for the strained sample, and to\n1388 kJ per mol for the strain-relaxed one, the Avrami exponent n=2.5(2) for\nboth samples, the rate constant equal to 0.0011(1) for the strained and to\n0.0028(1) per hour for the strained-free samples, respectively. The\nconcentration of Cr in the Fe-rich phase was revealed to be 11.6(4) at. % for\nthe strained sample, and to 13.2(4) at.% for the strain-free one. Significant\ndifferences in the values of the short-range parameters were revealed for the\ntwo samples. An average angle between the magnetization vector and the normal\nto the sample surface was equal to 52.7 deg for the strained sample, and to\n57.5 deg for the strain-relaxed one.",
        "positive": "Defect trapping and phase separation in chemically doped bulk AgF2: We report a computational survey of chemical doping of silver(II) fluoride,\nan oxocuprate analog. We find that the ground-state solutions exhibit strong\ntendency for localization of defects and for phase separation. The additional\nelectronic states are strongly localized and the resulting doped phases exhibit\ninsulating properties. Our results, together with previous insight from\nexperimental attempts, indicate that chemical doping may not be a feasible way\ntowards high-temperature superconductivity in bulk silver(II) fluoride."
    },
    {
        "anchor": "A Raman Investigation of PbZr0.94Ti0.06O3 Ceramics Under High-Pressures: We have investigated the behavior of the PbZr(0.94}Ti(0.06)O3 Raman spectra\nas a function of Hydrostatic pressures. The new structural phases were\nidentified based on previous works performed in PZT system with different Ti\nconcentrations at room- and high pressures. We showed that PbZr(0.94}Ti(0.06}O3\nexhibits a rich phase sequence up to 3.7 GPa: rhombohedral(LT) {0.3 GPa}\northorhombic(I) {2.9 GPa} orthorhombic(I'). This sequence is different from\nthat exhibited by PbZr(0.90)Ti(0.10)O3 suggesting a very interesting\nconcentration-pressure phase diagram for rich Zr PZT system.",
        "positive": "Effect of lattice geometry on magnon Hall effect in ferromagnetic\n  insulators: We have investigated the thermal Hall effect of magnons for various\nferromagnetic insulators. For pyrochlore ferromagnetic insulators\nLu$_2$V$_2$O$_7$, Ho$_2$V$_2$O$_7$, and In$_2$Mn$_2$O$_7$, finite thermal Hall\nconductivities have been observed below the Curie temperature $T_C$ . From the\ntemperature and magnetic field dependences, it is concluded that magnons are\nresponsible for the thermal Hall effect. The Hall effect of magnons can be well\nexplained by the theory based on the Berry curvature in momentum space induced\nby the Dzyaloshinskii-Moriya (DM) interaction. The analysis has been extended\nto the transition metal (TM) oxides with perovskite structure. The thermal Hall\nsignal was absent or far smaller in La$_2$NiMnO$_6$ and YTiO$_3$, which have\nthe distorted perovskite structure with four TM ions in the unit cell. On the\nother hand, a finite thermal Hall response is discernible below $T_C$ in\nanother ferromagentic perovskite oxide BiMnO$_3$, which shows orbital ordering\nwith a larger unit cell. The presence or absence of the thermal Hall effect in\ninsulating pyrochlore and perovskite systems reflect the geometric and\ntopological aspect of DM-induced magnon Hall effect."
    },
    {
        "anchor": "Lattice Thermal Conductivity of 2D Nanomaterials: A Simple\n  Semi-Empirical Approach: Extracting reliable information on certain physical properties of materials,\nlike thermal behavior, such as thermal transport, which can be very\ncomputationally demanding. Aiming to overcome such difficulties in the\nparticular case of lattice thermal conductivity (LTC) of 2D nanomaterials, we\npropose a simple, fast, and accurate semi-empirical approach for its\ncalculation.The approach is based on parameterized thermochemical equations and\nArrhenius-like fitting procedures, thus avoiding molecular dynamics or\n\\textit{ab initio} protocols, which frequently demand computationally expensive\nsimulations. As proof of concept, we obtain the LTC of some prototypical\nphysical systems, such as graphene (and other 2D carbon allotropes), hexagonal\nboron nitride (hBN), silicene, germanene, binary, and ternary BNC latices and\ntwo examples of the fullerene network family. Our values are in good agreement\nwith other theoretical and experimental estimations, nonetheless being derived\nin a rather straightforward way, at a fraction of the computational cost.",
        "positive": "Born effective charge removed anomalous temperature dependence of\n  lattice thermal conductivity in monolayer GeC: Due to potential applications in nano- and opto-electronics, two-dimensional\n(2D) materials have attracted tremendous interest. Their thermal transport\nproperties are closely related to the performance of 2D materials-based\ndevices. Here, the phonon transports of monolayer GeC with a perfect planar\nhexagonal honeycomb structure are investigated by solving the linearized phonon\nBoltzmann equation within the single-mode relaxation time approximation (RTA).\nWithout inclusion of Born effective charges ($Z^*$) and dielectric constants\n($\\varepsilon$), the lattice thermal conductivity ($\\kappa_L$) almost decreases\nlinearly above 350 K, deviating from the usual $\\kappa_L$$\\sim$$1/T$ law. The\nunderlying mechanism is because the contribution to $\\kappa_L$ from\nhigh-frequency optical phonon modes increases with increasing temperature, and\nthe contribution exceeds one from acoustic branches at high temperature. These\ncan be understood by huge phonon band gap caused by large difference in atom\nmass between Ge and C atoms, which produces important effects on scattering\nprocess involving high-frequency optical phonon. When considering $Z^*$ and\n$\\varepsilon$, the phonon group velocities and phonon lifetimes of\nhigh-frequency optical phonon modes are obviously reduced with respect to ones\nwithout $Z^*$ and $\\varepsilon$. The reduced group velocities and phonon\nlifetimes give rise to small contribution to $\\kappa_L$ from high-frequency\noptical phonon modes, which produces the the traditional $\\kappa_L$$\\sim$$1/T$\nrelation in monolayer GeC. Calculated results show that the isotope scattering\ncan also reduce anomalous temperature dependence of $\\kappa_L$ in monolayer\nGeC. Our works highlight the importance of $Z^*$ and $\\varepsilon$ to\ninvestigate phonon transports of monolayer GeC."
    },
    {
        "anchor": "Study of ortho-to-paraexciton conversion in Cu$_2$O by excitonic Lyman\n  spectroscopy: Using time-resolved $1s$-$2p$ excitonic Lyman spectroscopy, we study the\northoexciton-to-paraexcitons transfer, following the creation of a high density\npopulation of ultracold $1s$ orthoexcitons by resonant two-photon excitation\nwith femtosecond pulses.\n  An observed fast exciton-density dependent conversion rate is attributed to\nspin exchange between pairs of orthoexcitons.\n  Implication of these results on the feasibility of BEC of paraexcitons in\nCu$_2$O is discussed.",
        "positive": "Equivariant Networks for Crystal Structures: Supervised learning with deep models has tremendous potential for\napplications in materials science. Recently, graph neural networks have been\nused in this context, drawing direct inspiration from models for molecules.\nHowever, materials are typically much more structured than molecules, which is\na feature that these models do not leverage. In this work, we introduce a class\nof models that are equivariant with respect to crystalline symmetry groups. We\ndo this by defining a generalization of the message passing operations that can\nbe used with more general permutation groups, or that can alternatively be seen\nas defining an expressive convolution operation on the crystal graph.\nEmpirically, these models achieve competitive results with state-of-the-art on\nproperty prediction tasks."
    },
    {
        "anchor": "On the microscopic origin of reversible and irreversible reactions of\n  LiNixCoyMnx cathode materials: Ni-O hybrid bond formation vs. cationic and\n  anionic redox: Energy density limitations of layered oxides with different Ni contents,\ni.e., of the conventional cathode materials in Li-ion batteries, are\ninvestigated across the first discharge cycle using advanced spectroscopy and\nstate-of-the-art diffraction. For the first time unambiguous experimental\nevidence is provided, that redox reactions in NCMs proceed via a reversible\noxidation of Ni and a hybridization with O, and not, as widely assumed, via\npure cationic or more recently discussed, pure anionic redox processes. Once\nNi-O hybrid states are formed, the sites cannot be further oxidized. Instead,\nirreversible reactions set in which lead to a structural collapse and thus, the\nlack of ionic Ni limits the reversible capacity. Moreover, the degree of\nhybridization, which varies with the Ni content, triggers the electronic\nstructure and the operation potential of the cathodes. With an increasing\namount of Ni, the covalent character of the materials increases and the\npotential decreases.",
        "positive": "Mechanical Strain can Switch the Sign of Quantum Capacitance from\n  Positive to Negative: Quantum capacitance is a fundamental quantity that can directly reveal\nmany-body interactions among electrons and is expected to play a critical role\nin nanoelectronics. One of many tantalizing recent physical revelations about\nquantum capacitance is that it can posses a negative value, hence allowing for\nthe possibility of enhancing the overall capacitance in some particular\nmaterial systems beyond the scaling predicted by classical electrostatics.\nUsing detailed quantum mechanical simulations, we find an intriguing result\nthat mechanical strains can tune both signs and values of quantum capacitance.\nWe use a small coaxially-gated carbon nanotube as a paradigmatical capacitor\nsystem and show that, for the range of mechanical strain considered, quantum\ncapacitance can be adjusted from very large positive to very large negative\nvalues (in the order of plus/minus hundreds of attofarads), compared to the\ncorresponding classical geometric value (0.31035 aF). We elucidate the\nmechanisms underpinning the switching of the sign of quantum capacitance due to\nstrain. This finding opens novel avenues in designing quantum capacitance for\napplications in nanosensors, energy storage, and nanoelectronics."
    },
    {
        "anchor": "Magnetothermal properties of molecule-based materials: We critically review recent results obtained by studying the low-temperature\nspecific heat of some of the most popular molecular magnets. Perspectives of\nthis field are discussed as well.",
        "positive": "Direct vs. indirect optical recombination in Ge films grown on Si\n  substrates: The optical emission spectra from Ge films on Si are markedly different from\ntheir bulk Ge counterparts. Whereas bulk Ge emission is dominated by the\nmaterial's indirect gap, the photoluminescence signal from Ge films is mainly\nassociated with its direct band gap. Using a new class of Ge-on-Si films grown\nby a recently introduced CVD approach, we study the direct and indirect\nphotoluminescence from intrinsic and doped samples and we conclude that the\norigin of the discrepancy is the lack of self-absorption in thin Ge films\ncombined with a deviation from quasi-equilibrium conditions in the conduction\nband. The latter is confirmed by a simple model suggesting that the deviation\nfrom quasi-equilibrium is caused by the much shorter recombination lifetime in\nthe films relative to bulk Ge."
    },
    {
        "anchor": "Relaxation and derelaxation of pure and hydrogenated amorphous silicon\n  during thermal annealing experiments: The structural relaxation of pure amorphous silicon (a-Si) and hydrogenated\namorphous silicon (a-Si:H) materials, that occurs during thermal annealing\nexperiments, has been analysed by Raman spectroscopy and differential scanning\ncalorimetry. Unlike a-Si, the heat evolved from a-Si:H cannot be explained by\nrelaxation of the Si-Si network strain, but it reveals a derelaxation of the\nbond angle strain. Since the state of relaxation after annealing is very\nsimilar for pure and hydrogenated materials, our results give strong\nexperimental support to the predicted configurational gap between a-Si and\ncrystalline silicon.",
        "positive": "Spin reorientation in tetragonally distorted spinel oxide NiCo$_2$O$_4$\n  epitaxial films: We experimentally investigated the magnetic properties of NiCo$_2$O$_4$\nepitaxial films known to be conductive oxides with perpendicular magnetic\nanisotropy (PMA) at room temperature. Both magneto-torque and magnetization\nmeasurements at various temperatures provide clear experimental evidence of the\nspin reorientation transition at which the MA changes from PMA to easy-cone\nmagnetic anisotropy (ECMA) at a certain temperature ($T_{\\rm{SR}}$). ECMA was\ncommonly observed in films grown by pulsed laser deposition and reactive radio\nfrequency magnetron sputtering, although $T_{\\mathrm{SR}}$ is dependent on the\ngrowth method as well as the conditions. The cone angles measured from the\n$c$-axis increased successively at $T_{\\mathrm{SR}}$ and approached a maximum\nof 45-50 degrees at the lowest measurement temperature of 5 K. Calculation with\nthe cluster model suggests that the Ni$^{3+}$ ions occupying the $T_d$ site\ncould be the origin of the ECMA. Both the magnetic properties and the results\nof the calculation based on the cluster model indicate that the ECMA is\nattributable to the cation anti-site distribution of Ni$^{3+}$, which is\npossibly formed during the growth process of the thin films."
    },
    {
        "anchor": "Laplacian-level density functionals for the kinetic energy density and\n  exchange-correlation energy: We construct a Laplacian-level meta-generalized gradient approximation\n(meta-GGA) for the non-interacting (Kohn-Sham orbital) positive kinetic energy\ndensity $\\tau$ of an electronic ground state of density $n$. This meta-GGA is\ndesigned to recover the fourth-order gradient expansion $\\tau^{GE4}$ in the\nappropiate slowly-varying limit and the von Weizs\\\"{a}cker expression\n$\\tau^{W}=|\\nabla n|^2/(8n)$ in the rapidly-varying limit. It is constrained to\nsatisfy the rigorous lower bound $\\tau^{W}(\\mathbf{r})\\leq\\tau(\\mathbf{r})$.\nOur meta-GGA is typically a strong improvement over the gradient expansion of\n$\\tau$ for atoms, spherical jellium clusters, jellium surfaces, the Airy gas,\nHooke's atom, one-electron Gaussian density, quasi-two dimensional electron\ngas, and nonuniformly-scaled hydrogen atom. We also construct a Laplacian-level\nmeta-GGA for exchange and correlation by employing our approximate $\\tau$ in\nthe Tao, Perdew, Staroverov and Scuseria (TPSS) meta-GGA density functional.\nThe Laplacian-level TPSS gives almost the same exchange-correlation enhancement\nfactors and energies as the full TPSS, suggesting that $\\tau$ and $\\nabla^2 n$\ncarry about the same information beyond that carried by $n$ and $\\nabla n$. Our\nkinetic energy density integrates to an orbital-free kinetic energy functional\nthat is about as accurate as the fourth-order gradient expansion for many real\ndensities (with noticeable improvement in molecular atomization energies), but\nconsiderably more accurate for rapidly-varying ones.",
        "positive": "Colossal intrinsic exchange bias in epitaxial CoFe2O4/Al2O3 thin films: In this work, we demonstrate a massive intrinsic exchange bias (3 kOe) in\nepitaxial CoFe2O4(111) thin films deposited on Al2O3(0001) substrates. This\nexchange bias is indicative of intrinsic exchange or a ferromagnetic material\ncombined with an antiferromagnet. The analysis of structure, magnetism and\nelectronic states corroborate that there is an interfacial layer CoO between\nthe CoFe2O4(111) thin film and the Al2O3(0001) substrate. The power-law\nthickness dependence of the intrinsic exchange bias verifies its interfacial\norigin. This work suggests interfacial engineering can be an effective route\nfor achieving large exchange bias."
    },
    {
        "anchor": "Understanding Electronic Peculiarities in Tetragonal FeSe as Local\n  Structural Symmetry Breaking: Traditional band theory of perfect crystalline solids often uses as input the\nstructure deduced from diffraction experiments; when modeled by the minimal\nunit cell this often produces a spatially averaged model. The present study\nillustrates that this is not always a safe practice unless one examines if the\nintrinsic bonding mechanism is capable of benefiting from the formation of a\ndistribution of lower symmetry local environments that differ from the\nmacroscopically averaged structure. This can happen either due to positional,\nor due to magnetic symmetry breaking. By removing the constraint of a small\ncrystallographic cell, the energy minimization in the density functional theory\nfinds atomic and spin symmetry breaking, not evident in conventional\ndiffraction experiments but being found by local probes such as pair\ndistribution function analysis. Here we report that large atomic and electronic\nanomalies in bulk tetragonal FeSe emerge from the existence of distributions of\nlocal positional and magnetic moment motifs. The found symmetry-broken motifs\nobtained by minimization of the internal energy represent what chemical bonding\nin tetragonal phase prefers as an intrinsic energy lowering static distortions.\nThis explains observations of band renormalization, predicts orbital order and\nenhanced nematicity, and provides unprecedented close agreement with spectral\nfunction measured by photoemission and local atomic environment revealed by\npair distribution function. While the symmetry-restricted strong correlation\napproach has been argued previously to be the exclusive theory needed for\ndescribing the main peculiarities of FeSe, we show here that the\nsymmetry-broken mean-field approach addresses numerous aspects of the problem,\nprovides intuitive insight into the electronic structure, and opens the door\nfor large-scale mean-field calculations for similar d-electron quantum\nmaterials.",
        "positive": "Ferroelectric metal-oxide-semiconductor capacitors using ultrathin\n  single crystalline SrZrxTi1-xO3: The epitaxial growth of multifunctional oxides on semiconductors has opened a\npathway to introduce new functionalities to semiconductor device technologies.\nIn particular, ferroelectric materials integrated on semiconductors could lead\nto low-power field-effect devices that can be used for logic and memory.\nEssential to realizing such field-effect devices is the development of\nferroelectric metal-oxide-semiconductor (MOS) capacitors, in which the\npolarization of a ferroelectric gate is coupled to the surface potential of a\nsemiconducting channel. Here we demonstrate that ferroelectric MOS capacitors\ncan be realized using single crystalline SrZrxTi1-xO3 (x = 0.7) that has been\nepitaxially grown on Ge. We find that the ferroelectric properties of\nSrZrxTi1-xO3 are exceptionally robust, as gate layers as thin as 5 nm\ncorresponding to an equivalent-oxide-thickness of just 1.0 nm exhibit a ~ 2 V\nhysteretic window in the capacitance-voltage characteristics. The development\nof ferroelectric MOS capacitors with nanoscale gate thicknesses opens new\nvistas for nanoelectronic devices."
    },
    {
        "anchor": "Influence of twist boundary on deformation behaviour of <100> BCC Fe\n  nanowires: Molecular dynamics simulations revealed significant difference in deformation\nbehaviour of $<$100$>$ BCC Fe nanowires with and without twist boundary. The\nplastic deformation in perfect $<$100$>$ BCC Fe nanowire was dominated by\ntwinning and reorientation to $<$110$>$ followed by further deformation by slip\nmode. On the contrary, $<$100$>$ BCC Fe nanowire with a twist boundary deformed\nby slip at low plastic strains followed by twinning at high strains and absence\nof full reorientation. The results suggest that the deformation in $<$100$>$\nBCC Fe nanowire by dislocation slip is preferred over twinning in the presence\nof initial dislocations or dislocation networks. The results also explain the\nabsence of extensive twinning in bulk materials, which inherently contains\nlarge number of dislocations.",
        "positive": "Emergence of Two-Dimensional Massless Dirac Fermions, Chiral\n  Pseudospins, and Berry's Phase in Potassium Doped Few-Layer Black Phosphorus: Thin flakes of black phosphorus (BP) are a two-dimensional (2D) semiconductor\nwhose energy gap is predicted being sensitive to the number of layers and\nexternal perturbations. Very recently, it was found that a simple method of\npotassium (K) doping on the surface of BP closes its band gap completely,\nproducing a Dirac semimetal state with a linear band dispersion in the armchair\ndirection and a quadratic one in the zigzag direction. Here, based on\nfirst-principles density functional calculations, we predict that, beyond the\ncritical K density of the gap closure, 2D massless Dirac Fermions (i.e., Dirac\ncones) emerge in K-doped few-layer BP, with linear band dispersions in all\nmomentum directions, and the electronic states around Dirac points have chiral\npseudospins and Berry's phase. These features are robust with respect to the\nspin-orbit interaction and may lead to graphene-like electronic transport\nproperties with greater flexibility for potential device applications."
    },
    {
        "anchor": "Dielectric behavior of Water in [bmim] [Tf 2 N] room-temperature Ionic\n  Liquid, molecular dynamic study: In this work we present the dielectric behavior of water with a novel\nflexible model that improved all three sites water models Different\nconcentrations of the ionic liquid 1- butyl-3-methylimidazolium [bmim]\nbis(trifluoromethanesulfonyl)imide [Tf 2 N] with water was investigated. The\nstudy was performed by molecular dynamics simulations using three water models,\nbeing two non-polarizable 3-site SPC/E and SPC/e, and a novel flexible 3-site\nFAB/epsilon model. Systematic thermodynamics, dynamical and dielectric\nproperties were investigated, such as density, diffusion coefficient, heat of\nvaporization Delta-Hvap, and surface tension at 300 K and 1 bar. We\nextrapolated the experimental molar fraction of the mixtures and a pattern\nchange for all properties was observed, evidencing the phase separation\npreviously reported by experimental data. The results also display the\ndielectric effect of the system on the calculated properties.",
        "positive": "Mechanics of disordered auxetic metamaterials: Auxetic materials are of great engineering interest not only because of their\nfascinating negative Poisson's ratio, but also due to their increased toughness\nand indentation resistance. These materials are typically synthesized polyester\nfoams with a very heterogeneous structure, but the role of disorder in auxetic\nbehavior is not fully understood. Here, we provide a systematic theoretical and\nexperimental investigation in to the effect of disorder on the mechanical\nproperties of a paradigmatic auxetic lattice with a re-entrant hexagonal\ngeometry. We show that disorder has a marginal effect on the Poisson's ratio\nunless the lattice topology is altered, and in all cases examined the disorder\npreserves the auxetic characteristics. Depending on the direction of loading\napplied to these disordered auxetic lattices, either brittle or ductile failure\nis observed. It is found that brittle failure is associated with a\ndisorder-dependent tensile strength, whereas in ductile failure disorder does\nnot affect strength. Our work thus provides general guidelines to optimize\nelasticity and strength of disordered auxetic metamaterials."
    },
    {
        "anchor": "Shubnikov-de Haas and de Haas-van Alphen oscillations in topological\n  semimetal CaAl4: We report the magneto-transport properties of CaAl$_4$ single crystals with\n$C2/m$ structure at low temperature. CaAl$_4$ exhibits large unsaturated\nmagnetoresistance $\\sim$3000$\\%$ at 2.5 K and 14 T. The nonlinear Hall\nresistivity is observed, which indicates the multi-band feature. The\nfirst-principles calculations show the electron-hole compensation and the\ncomplex Fermi surface in CaAl$_4$, to which the two-band model with\nover-simplified carrier mobility can't completely apply. Evident quantum\noscillations have been observed with B//c and B//ab configurations, from which\nthe nontrivial Berry phase is extracted by the multi-band Lifshitz-Kosevich\nformula fitting. An electron-type quasi-2D Fermi surface is found by the\nangle-dependent Shubnikov-de Haas oscillations, de Haas-van Alphen oscillations\nand the first-principles calculations. The calculations also elucidate that\nCaAl$_4$ owns a Dirac nodal line type band structure around the $\\Gamma$ point\nin the $Z$-$\\Gamma$-$L$ plane, which is protected by the mirror symmetry as\nwell as the space inversion and time reversal symmetries. Once the spin-orbit\ncoupling is included, the crossed nodal line opens a negligible gap (less than\n3 meV). The open-orbit topology is also found in the electron-type Fermi\nsurfaces, which is believed to help enhance the magnetoresistance observed.",
        "positive": "Nonlinear Coarse-graining Models for 3D Printed Multi-material\n  Biomimetic Composites: Bio-inspired composites are a great promise for mimicking the extraordinary\nand highly efficient properties of natural materials. Recent developments in\nvoxel-by-voxel 3D printing have enabled extreme levels of control over the\nmaterial deposition, yielding complex micro-architected materials. However,\nspatial complexity makes it a formidable challenge to find the optimal\ndistribution of both hard and soft phases. To address this, a nonlinear\ncoarse-graining approach is developed, where foam-based constitutive equations\nare used to predict the mechanics of biomimetic composites. The proposed\napproach is validated by comparing coarse-grained finite element predictions\nagainst full-field strain distributions measured using digital image\ncorrelation. To evaluate the degree of coarse-graining on model accuracy,\npre-notched specimens decorated with a binarized version of a renowned painting\nwere modeled. Subsequently, coarse-graining is used to predict the fracture\nbehavior of bio-inspired composites incorporating complex designs, such as\nfunctional gradients and hierarchical organizations. Finally, as a showcase of\nthe proposed approach, the inverse coarse-graining is combined with a\ntheoretical model of bone tissue adaptation to optimize the microarchitecture\nof a 3D-printed femur. The predicted properties were in exceptionally good\nagreement with the corresponding experimental results. Therefore, the\ncoarse-graining method allows the design of advanced architected materials with\ntunable and predictable properties."
    },
    {
        "anchor": "Evidence for pressure-induced node-pair annihilation in Cd3As2: As an intermediate state in the topological phase diagram, Dirac semimetals\nare of particular interest as a platform for studying topological phase\ntransitions under external modulations. Despite a growing theoretical interest\nin this topic, it remains a substantial challenge to experimentally tune the\nsystem across topological phase transitions. Here, we investigate the Fermi\nsurface evolution of Cd3As2 under high pressure through magnetotransport. A\nsudden change in Berry phase occurs at 1.3 GPa along with the unanticipated\nshrinkage of the Fermi surface, which occurs well below the structure\ntransition point (~2.5 GPa). High pressure X-ray diffraction also reveals an\nanisotropic compression of the Cd3As2 lattice around a similar pressure.\nCorroborated by the first-principles calculations we show that an axial\ncompression will shift the Dirac nodes towards the Brillouin zone center and\neventually introduces a finite energy gap. The ability to tune the node\nposition, a vital parameter of Dirac semimetals, can have dramatic impacts on\nthe corresponding topological properties such as the Fermi arc surface states\nand the chiral anomaly. Our study demonstrates axial compression as an\nefficient approach for manipulating the band topology and exploring the\ncritical phenomena near the topological phase transition in Cd3As2.",
        "positive": "The quasi-free-standing nature of graphene on H-saturated SiC(0001): We report on an investigation of quasi-free-standing graphene on 6H-SiC(0001)\nwhich was prepared by intercalation of hydrogen under the buffer layer. Using\ninfrared absorption spectroscopy we prove that the SiC(0001) surface is\nsaturated with hydrogen. Raman spectra demonstrate the conversion of the buffer\nlayer into graphene which exhibits a slight tensile strain and short range\ndefects. The layers are hole doped (p = 5.0-6.5 x 10^12 cm^(-2)) with a carrier\nmobility of 3,100 cm^2/Vs at room temperature. Compared to graphene on the\nbuffer layer a strongly reduced temperature dependence of the mobility is\nobserved for graphene on H-terminated SiC(0001)which justifies the term\n\"quasi-free-standing\"."
    },
    {
        "anchor": "An Atomic-resolution nanomechanical mass sensor: Mechanical resonators are widely used as inertial balances to detect small\nquantities of adsorbed mass through shifts in oscillation frequency[1].\nAdvances in lithography and materials synthesis have enabled the fabrication of\nnanoscale mechanical resonators[2, 3, 4, 5, 6], which have been operated as\nprecision force[7], position[8, 9] and mass sensors[10, 11, 12, 13, 14, 15].\nHere we demonstrate a room-temperature, carbon-nanotube-based nanomechanical\nresonator with atomic mass resolution. This device is essentially a mass\nspectrometer with a mass sensitivity of 1.3 times 10^-25 kg Hz^-1/2 or,\nequivalently, 0.40 gold atoms Hz^-1/2. Using this extreme mass sensitivity, we\nobserve atomic mass shot noise, which is analogous to the electronic shot\nnoise[16, 17] measured in many semiconductor experiments. Unlike traditional\nmass spectrometers, nanomechanical mass spectrometers do not require the\npotentially destructive ionization of the test sample, are more sensitive to\nlarge molecules, and could eventually be incorporated on a chip.",
        "positive": "Unraveling Energetic Disorder in Organic Bulk Heterojunction\n  Photovoltaics by Capacitance-Voltage Spectroscopy: Organic semiconductors possess an intrinsic energetic disorder\ncharacteristic, which holds an exceptionally important role for understanding\norganic photovoltaic (OPV) operation and future optimization. We performed\nillumination intensity dependence of capacitance-voltage (C-V) measurements in\nPIDTDTQx:PC70BM based organic bulk heterojunction (BHJ) photovoltaics in\nworking conditions. Energetic disorder profiles for the photo-active layer,\nPIDTDTQx:PC70BM, changed significantly when different interfaces were involved.\nThe effects of energetic disorder that could be reflected from C-V profiles are\nincorporated through an exponential or Gaussian model of density of states\n(DOS), or a combination of these two. Results underlie that an identical\norganic blend in BHJ solar cells exhibits different energetic disorder when it\ninteracts with various interfaces. It may, thus, has a certain impact on OPV\nperformances, such as open-circuit voltage (V_oc ). Our study provides device\nphysicists a different perspective view for tailoring the organic energetic\ndisorder parameter via interfaces in order to enhance photo-electron conversion\nefficiencies (PCE)."
    },
    {
        "anchor": "Current Induced Fingering Instability in Magnetic Domain Walls: The shape instability of magnetic domain walls under current is investigated\nin a ferromagnetic (Ga,Mn)(As,P) film with perpendicular anisotropy. Domain\nwall motion is driven by the spin transfer torque mechanism. A current density\ngradient is found either to stabilize domains with walls perpendicular to\ncurrent lines or to produce finger-like patterns, depending on the domain wall\nmotion direction. The instability mechanism is shown to result from the\nnon-adiabatic contribution of the spin transfer torque mechanism.",
        "positive": "Compact Modeling of 0.35 micron SOI CMOS Technology Node for 4 K DC\n  Operation using Verilog-A: Compact modeling of MOSFETs from a 0.35 micron SOI technology node operating\nat 4 K is presented. The Verilog-A language is used to modify device equations\nfor BSIM models and more accurately reproduce measured DC behavior, which is\nnot possible with the standard BSIM model set. The Verilog-A approach also\nallows the embedding of nonlinear length, width and bias effects into BSIM\ncalculated curves beyond those that can be achieved by the use of different\nBSIM parameter sets. Nonlinear dependences are necessary to capture effects\nparticular to 4 K behavior, such as current kinks. The 4 K DC behavior is\nreproduced well by the compact model and the model seamlessly evolves during\nsimulation of circuits and systems as the simulator encounters SOI MOSFETs with\ndifferent lengths and widths. The incorporation of various length/width and\nbias dependent effects into one Verilog-A / BSIM4 library, therefore, produces\none model for all sets of devices for this technology node."
    },
    {
        "anchor": "Spatially resolved optical spectroscopy in extreme environment of low\n  temperature, high magnetic fields and high pressure: We present an experimental set-up developed to perform optical spectroscopy\nexperiments (Raman scattering and photoluminescence measurements) with a\nmicrometer spatial resolution, in an extreme environment of low temperature,\nhigh magnetic field and high pressure. This unique experimental setup, to the\nbest of our knowledge, allows us to explore deeply the phase diagram of\ncondensed matter systems by tuning independently these three thermodynamic\nparameters, while monitoring the low-energy excitations (electronic, phononic\nor magnetic excitations), to spatially map the Raman scattering response or to\ninvestigate objects with low dimensions. We apply this technique to bulk FePS3,\na layered antiferromagnet with a Neel temperature of T = 120 K.",
        "positive": "Chemical trends of deep levels in van der Waals semiconductors: Properties of semiconductors are largely defined by crystal imperfections\nincluding native defects. Van der Waals (vdW) semiconductors, a newly emerged\nclass of materials, are no exception: defects exist even in the purest\nmaterials and strongly affect their electrical, optical, magnetic, catalytic\nand sensing properties. However, unlike conventional semiconductors where\nenergy levels of defects are well documented, they are experimentally unknown\nin even the best studied vdW semiconductors, impeding the understanding and\nutilization of these materials. Here, we directly evaluate deep levels and\ntheir chemical trends in the bandgap of MoS2, WS2 and their alloys by transient\nspectroscopic study. One of the deep levels is found to follow the conduction\nband minimum of each host, attributed to the native sulfur vacancy. A\nswitchable, DX center - like deep level has also been identified, whose energy\nlines up instead on a fixed level across different hosts, explaining a\npersistent photoconductivity above 400K."
    },
    {
        "anchor": "Giant magnetocaloric effect in the (Mn,Fe)NiSi-system: The search for energy-efficient and environmentally friendly cooling\ntechnologies is a key driver for the development of magnetic refrigeration\nbased on the magnetocaloric effect (MCE). This phenomenon arises from the\ninterplay between magnetic and lattice degrees of freedom that is strong in\ncertain materials, leading to a change in temperature upon application or\nremoval of a magnetic field. Here we report on a new material,\nMn$_{1-x}$Fe$_x$NiSi$_{0.95}$Al$_{0.05}$, with an exceptionally large\nisothermal entropy at room temperature. By combining experimental and\ntheoretical methods we outline the microscopic mechanism behind the large MCE\nin this material. It is demonstrated that the competition between the\nNi$_2$In-type hexagonal phase and the MnNiSi-type orthorhombic phase, that\ncoexist in this system, combined with the distinctly different magnetic\nproperties of these phases, is a key parameter for the functionality of this\nmaterial for magnetic cooling.",
        "positive": "Presence of a monoclinic (Pm) phase in the morphotropic phase boundary\n  region of multiferroic (1-x)Bi(Ni1/2Ti1/2)O3-xPbTiO3 solid solution: A\n  Rietveld study: We present here the results of structural studies on multiferroic\n(1-x)Bi(Ni1/2Ti1/2)O3-xPbTiO3 solid solution using Rietveld analysis on powder\nx-ray diffraction data in the composition range 0.35 to 0.55. We have\ndetermined precisely the stability region of various crystallographic phases at\nroom temperature for (1-x)Bi(Ni1/2Ti1/2)O3-xPbTiO3 . Structural transformation\nfrom pseudo-cubic to tetragonal phase is observed via phase coexistence region\ndemarcating the morphotropic phase boundary region. The morphotropic phase\nboundary region consists of coexisting tetragonal and monoclinic structures\nwith space group P4mm and Pm respectively, stable in composition ranges 0.41 to\n0.49 as confirmed by Rietveld analysis. The results of Rietveld analysis\ncompletely rules out the coexistence of rhombohedral and tetragonal phases in\nthe morphotropic phase boundary region reported by earlier workers. A\ncomparison between the bond lengths for B-site cations- oxygen anions obtained\nafter Rietveld refinement, with the bond length calculated using\nShannon-Prewitt ionic radii, reveals the ionic nature of B-O bonds for the\ncubic phases and partial covalent character for the other crystallographic\nphases."
    },
    {
        "anchor": "Giant unidirectional magnetoresistance in topological insulator --\n  ferromagnetic semiconductor heterostructures: The unidirectional magnetoresistance (UMR) is one of the most complex\nspin-dependent transport phenomena in ferromagnet/non-magnet bilayers, which\ninvolves spin injection and accumulation due to the spin Hall effect (SHE) or\nRashba-Edelstein effect (REE), spin-dependent scattering, and magnon scattering\nat the interface or in the bulk of the ferromagnet. While UMR in metallic\nbilayers has been studied extensively in very recent years, its magnitude is as\nsmall as 10$^-$$^5$, which is too small for practical applications. Here, we\ndemonstrate a giant UMR effect in a heterostructure of BiSb topological\ninsulator -- GaMnAs ferromagnetic semiconductor. We obtained a large UMR ratio\nof 1.1%, and found that this giant UMR is governed not by the giant\nmagnetoresistance (GMR)-like spin-dependent scattering, but by magnon\nemission/absorption and strong spin-disorder scattering in the GaMnAs layer.\nOur results provide new insight into the complex physics of UMR, as well as a\nstrategy for enhancing its magnitude for device applications.",
        "positive": "Exciton Mott Transition in Two-Dimensional Semiconductors: Exciton many-body interaction bear great implication for application in\nadvanced photonic devices and quantum science and technology such as quantum\ncomputing, but the fundamental understanding about exciton many-body\ninteraction is very limited. Here we provide numerous new insights into the\nfundamentals of exciton Mott transition (EMT), a manifestation of exciton\nmany-body interaction evidenced by the ionization of excitons into a plasma of\nunbound electrons and holes, i.e. electron-hole plasma (EHP), by taking\nadvantage of the unique properties of two-dimensional (2D) semiconductors like\nmonolayer MoS2. We clarify long-standing controversies on the continuousness\nand criteria of EMT, quantify the charge carrier distribution among the\nco-existing exciton and EHP phases, establish correlation between the emission\nfeatures and charge densities of EHP, and elucidate the physical state of EHP\ncharge carriers as nanoscale electron-hole complex rather than individually\nfree charges. These results lay down a foundation for furthering the studies of\nexciton many-body interaction and also for utilizing the interaction in quantum\nscience/technology and the development of advanced optoelectronic devices."
    },
    {
        "anchor": "Effects of biaxial strain and local constant potential on electronic\n  structure of monolayer SnSe: We use the modified Becke-Johnson exchange potential (mBJ) with the\nspin-orbit coupling effect (SOC) to study effects of biaxial strain and local\nconstant potential on electronic structure of monolayer SnSe. Our results show\nthe fundamental band gap size can be tuned via biaxial strain. Compressive\nstrain (tensile strain) can narrow (enlarge) band gap, and compressive strain\ncauses the transition from quasi-direct to indirect band gap. Moreover,\nconsidering that any tuning of electronic structure is realized by changing the\nperiodic potential distribution in the crystalline, we directly add constant\npotential (CP) to muffin-tin spheres. The results demonstrate that positive and\nnegative CPs can narrow and enlarge band gap, respectively. At CP of 0.9 Ry,\nsemiconductor-metal transition appears, and interestingly a new type of nearly\nlinear dispersions occur at band edge. Our work is good for inspiring more\nexperimental and further theoretical research works.",
        "positive": "Cluster expansion constructed over Jacobi-Legendre polynomials for\n  accurate force fields: We introduce a compact cluster expansion method, constructed over Jacobi and\nLegendre polynomials, to generate highly accurate and flexible machine-learning\nforce fields. The constituent many-body contributions are separated,\ninterpretable and adaptable to replicate the physical knowledge of the system.\nIn fact, the flexibility introduced by the use of the Jacobi polynomials allows\nus to impose, in a natural way, constrains and symmetries to the cluster\nexpansion. This has the effect of reducing the number of parameters needed for\nthe fit and of enforcing desired behaviours of the potential. For instance, we\nshow that our Jacobi-Legendre cluster expansion can be designed to generate\npotentials with a repulsive tail at short inter-atomic distances, without the\nneed of imposing any external function. Our method is here continuously\ncompared with available machine-learning potential schemes, such as the atomic\ncluster expansion and potentials built over the bispectrum. As an example we\nconstruct a Jacobi-Legendre potential for carbon, by training a slim and\naccurate model capable of describing crystalline graphite and diamond, as well\nas liquid and amorphous elemental carbon."
    },
    {
        "anchor": "Analytical solutions for the interstitial diffusion of impurity atoms: The analytical solutions of the equations describing impurity diffusion due\nto migration of nonequilibrium impurity interstitials were obtained for the\nimpurity redistribution during ion implantation at elevated temperatures and\nfor diffusion from a doped epitaxial layer. The reflecting boundary condition\nat the surface of a semiconductor and the conditions of constant concentrations\nat the surface and in the bulk of it were used in the first and second cases,\nrespectively. On the basis of these solutions hydrogen diffusion in silicon\nduring high-fluence low-energy deuterium implantation and beryllium diffusion\nfrom a doped epi-layer during rapid thermal annealing of InP/InGaAs\nheterostructures were investigated. The calculated impurity concentration\nprofiles agree well with experimental data. The fitting to the experimental\nprofiles allowed us to derive the values of the parameters that describe\ninterstitial impurity diffusion.",
        "positive": "Pentazole and Ammonium Pentazolate: Crystalline Hydro-Nitrogens at High\n  Pressure: Two new crystalline compounds, pentazole (N_{5}H) and ammonium pentazolate\n(NH_{4})(N_{5}), both featuring cyclo-{\\rm N_{5}^{-}} are discovered using\nfirst principles evolutionary search of the nitrogen-rich portion of the\nhydro-nitrogen binary phase diagram (N_{x}H_{y}, x\\geqy) at high pressures.\nBoth crystals consist of the pentazolate N_{5}^{-} anion and ammonium\nNH_{4}^{+} or hydrogen H^{+} cations. These two crystals are predicted to be\nthermodynamically stable at pressures above 30 GPa for (NH_{4})(N_{5}) and 50\nGPa for pentazole N_{5}H. The chemical transformation of ammonium azide\n(NH_{4})(N_{3}) mixed with di-nitrogen (N_{2}) to ammonium pentazolate\n(NH_{4})(N_{5}) is predicted to become energetically favorable above 12.5 GPa.\nTo assist in identification of newly synthesized compounds in future\nexperiments, the Raman spectra of both crystals are calculated and mode\nassignments are made as a function of pressure up to 75 GPa."
    },
    {
        "anchor": "Classical nucleation theory in ordering alloys precipitating with L12\n  structure: By means of low-temperature expansions (LTEs), the nucleation free energy and\nthe precipitate interface free energy are expressed as functions of the\nsolubility limit for alloys which lead to the precipitation of a stoichiometric\nL12 compound such as Al-Sc or Al-Zr alloys. Classical nucleation theory is then\nused to obtain a simple expression of the nucleation rate whose validity is\ndemonstrated by a comparison with atomic simulations. LTEs also explain why\nsimple mean-field approximation like the Bragg-Williams approximation fails to\npredict correct nucleation rates in such an ordering alloy.",
        "positive": "Towards quantitative Low Energy Ion Scattering on CaSiO$_3$ from\n  Comparison to Multiple-Scattering-Resolved Dynamical Binary Collision\n  Approximation Simulations: We perform Low Energy Ion Scattering with 1\\,keV He ions on CaSiO$_3$ using a\ncommercial electrostatic detector system and determine the charge fraction of\nscattered ions from comparison with Binary Collision Approximation simulations.\nThe simulations take dynamical surface changes due to surface cleaning Ar\nsputtering into account and scattered He particles are separated into single,\ndual, and multiple scattering trajectories. We find that the charge fraction of\nsingle and dual scattered He is about 10 times higher than the one for multiple\ncollisions. Our results show that quantitative concentration profiles can be\ninferred from this method, if the charge fraction components are determined\nfirst."
    },
    {
        "anchor": "Proximity Effects in Topological Insulator Heterostructures: Topological insulators (TIs) are bulk insulators that possess robust helical\nconducting states along their interfaces with conventional insulators. A\ntremendous research effort has recently been devoted to TI-based\nheterostructures, in which conventional proximity effects give rise to a series\nof exotic physical phenomena. This paper reviews our recent works on the\npotential existence of topological proximity effects at the interface between a\ntopological insulator and a normal insulator or other topologically trivial\nsystems. Using first-principles approaches, we have established the tunability\nof the vertical location of the topological helical state via intriguing\ndual-proximity effects. To further elucidate the control parameters of this\neffect, we have used the graphene-based heterostructures as prototypical\nsystems to reveal a more complete phase diagram. On the application side of the\ntopological helical states, we have presented a catalysis example, where the\ntopological helical state plays an essential role in facilitating surface\nreactions by serving as an effective electron bath. These discoveries lay the\nfoundation for accurate manipulation of the real space properties of the\ntopological helical state in TI-based heterostructures and pave the way for\nrealization of the salient functionality of topological insulators in future\ndevice applications.",
        "positive": "A versatile scanning acoustic platform: We present a versatile and highly configurable scanning acoustic platform.\nThis platform, comprising of a high frequency transducer, bespoke positioning\nsystem and temperature-regulated sample unit, enables the acoustic probing of\nmaterials over a wide range of length scales and with minimal thermal\naberration. In its bare form the platform acts as a reflection-mode acoustic\nmicroscope, while optical capabilities are readily incorporated to extend its\nabilities to the acousto-optic domain. Here we illustrate the capabilities of\nthe platform through its incarnation as an acoustic microscope. Operating at 55\nMHz we demonstrate acoustic imaging with a lateral resolution of 25 microns. We\noutline its construction, calibration and capabilities as an acoustic\nmicroscope, and discuss its wider applications."
    },
    {
        "anchor": "Switching a polar metal via strain gradients: Although rare, spontaneous breakdown of inversion symmetry sometimes occurs\nin a material which is metallic: these are commonly known as polar metals or\nferroelectric metals. Their 'polarization', however, cannot be switched via an\nelectric field, which limits the experimental control over band topology. Here\nwe shall investigate, via first-principles theory, flexoelectricity as a\npossible way around this obstacle with the well known polar metal LiOsO$_3$.\nThe flexocoupling coefficients are computed for this metal with high accuracy\nwith a completely new approach based on real-space sums of the inter-atomic\nforce constants. A Landau-Ginzburg-Devonshire-type first-principles Hamiltonian\nis built and a critical bending radius to switch the material is estimated,\nwhose order of magnitude is comparable to that of BaTiO$_3$.",
        "positive": "Structure and properties of the films based on ternary transition metal\n  borides: theory and experiment: The review presents the results of theoretical and experimental studies of\nthe structure, bonding between atoms, mechanical properties, thermal stability,\nand oxidation and corrosion resistance of films based on ternary transition\nmetal borides."
    },
    {
        "anchor": "Direct observation of local Rashba spin polarization and spin-layer\n  locking in centrosymmetric monolayer PtSe$_2$: The generally accepted view that spin polarization is induced by the\nasymmetry of the global crystal space group has limited the search for\nspintronics [1] materials to non-centrosymmetric materials. Recently it has\nbeen suggested that spin polarization originates fundamentally from local\natomic site asymmetries [2], and therefore centrosymmetric materials may\nexhibit previously overlooked spin polarizations. Here by using spin- and\nangle-resolved photoemission spectroscopy (spin-ARPES), we report helical spin\ntexture induced by local Rashba effect (R-2) in centrosymmetric monolayer\nPtSe$_2$ film. First-principles calculations and effective analytical model\nsupport the spin-layer locking picture: in contrast to the spin splitting in\nconventional Rashba effect (R-1), the opposite spin polarizations induced by\nR-2 are degenerate in energy while spatially separated in the top and bottom Se\nlayers. These results not only enrich our understanding of spin polarization\nphysics, but also may find applications in electrically tunable spintronics.",
        "positive": "Structure, elastic properties and strength of amorphous and\n  nanocomposite carbon: We study theoretically the equilibrium structure, as well as the response\nunder external load, of characteristic carbon-based materials. The materials\nconsidered include diamond, amorphous carbon (a-C), ``amorphous diamond'' and\nnanocomposite amorphous carbon (na-C). A universal bulk-modulus versus density\ncurve is obeyed by all structures we consider. We calculate the dependence of\nelastic constants on the density. The strength of a-C was found to increase in\nroughly a linear manner, with increasing concentration of four-fold atoms, with\nthe maximum stress of the strongest a-C sample being about half that of\ndiamond. The response of na-C to external load is essentially identical to the\nresponse of the embedding a-C matrix."
    },
    {
        "anchor": "Evolution of the interfacial perpendicular magnetic anisotropy constant\n  of the Co$_2$FeAl/MgO interface upon annealing: We investigate thickness series of films of the Heusler alloy Co$_2$FeAl in\norder to study the effect of annealing on the interface with a MgO layer and on\nthe bulk magnetic properties. Our results reveal that while the perpendicular\ninterface anisotropy constant $K^{\\perp}_{\\rm S}$ is zero for the as-deposited\nsamples, its value increases with annealing up to a value of $1.14\\, \\pm\n\\,0.07$~mJ/m$^2$ for the series annealed at 320$^{\\rm o}$C and of $2.07\\, \\pm\n\\,0.7$~mJ/m$^2$ for the 450$^{\\rm o}$C annealed series owing to a strong\nmodification of the interface during the thermal treatment. This large value\nensures a stabilization of a perpendicular magnetization orientation for a\nthickness below 1.7~nm. The data additionally shows that the in-plane biaxial\nanisotropy constant has a different evolution with thickness in as-deposited\nand annealed systems. The Gilbert damping parameter $\\alpha$ shows minima for\nall series for a thickness of 40~nm and an absolute minimum value of\n$2.8\\pm0.1\\cdot10^{-3}$. The thickness dependence is explained in terms of an\ninhomogenous magnetization state generated by the interplay between the\ndifferent anisotropies of the system and by crystalline disorder.",
        "positive": "Modelling functional properties of ferroelectric oxide thin films with a\n  three-domain structure: The properties of a ferroelectric, (001)-oriented, thin film clamped to a\nsubstrate are investigated analytically and numerically. The emphasis is on the\ntetragonal, polydomain, ferroelectric phase, using a three domain structure, as\nis observed experimentally. The previously used, very restrictive set of\nboundary conditions, arising from the domain walls, is relaxed, creating more\nmodes for energy relaxation. It is argued that this approach gives a more\nrealistic description of the clamped ferroelectric film.\n  It is shown that for the ferroelectric oxides PbZr_(1-x)Ti_xO_3} the\ntetragonal, polydomain phase is present over a wide range of substrate induced\nstrains for x_Ti>0.5, corresponding to the tetragonal side of the bulk phase\ndiagram. A polydomain, rhombohedral phase is present for x_Ti<0.5, at the bulk\nrhombohedral side. Phase-temperature diagrams, and ferroelectric, dielectric\nand piezoelectric properties, as well as lattice parameters, are calculated as\nfunction of substrate induced strain and applied field. The analytical\nformulation allows the decomposition of these properties into three different\ncauses: domain wall motion, field induced elastic effects and piezoelectric\neffects. It is found that domain wall motion and polarization rotation of the\nin-plane oriented domains under an applied field contribute most to the\nproperties, while the out-of-plane oriented domains hardly contribute."
    },
    {
        "anchor": "Harmonic generation predominantly from a single spin channel in a half\n  metal: Harmonic generation in atoms and molecules has reshaped our understanding of\nultrafast phenomena beyond the traditional nonlinear optics and has launched\nattosecond physics. Harmonics from solids represent a new frontier, where both\nmajority and minority spin channels contribute to harmonics.} This is true even\nin a ferromagnet whose electronic states are equally available to optical\nexcitation. Here, we demonstrate that harmonics can be generated {mostly} from\na single spin channel in half metallic chromium dioxide. {An energy gap in the\nminority channel greatly reduces the harmonic generation}, so harmonics\npredominantly emit from the majority channel, with a small contribution from\nthe minority channel. However, this is only possible when the incident photon\nenergy is well below the energy gap in the minority channel, so all the\ntransitions in the minority channel are virtual. The onset of the photon energy\nis determined by the transition energy between the dipole-allowed transition\nbetween the O-$2p$ and Cr-$3d$ states. Harmonics {mainly} from a single spin\nchannel can be detected, regardless of laser field strength, as far as the\nphoton energy is below the minority band energy gap. This prediction should be\ntested experimentally.",
        "positive": "Role of Zn in obtaining of semi-insulating CdZnTe crystals for ionizing\n  radiations detectors: Studies of n-CdZnTe crystals (photoluminescence, extrinsic photoconductivity,\nHall effect, time-of-flight technique) have shown that the excess concentration\nof vacancies of cadmium (Vcd) is the main reason of low, as a rule, values of\nproduct of mobility to life time of holes (mhth). The reduction of the\nconcentration of cadmium vacancies (decreasing of the intensity of near 1eV\nphotoluminescence band and an intensity of the (0.9-1.3) eV extrinsic\nphotoconductivity band) by annealing of the crystals at 600 C results in\nincreasing of value of mhth.\n  Influence of Zn on formation of the basic photoelectric properties of CdZnTe\ncrystals has been explained by \"self-control\" of a concentration of cadmium\nvacancies Vcd due to addition of Zn results in formation of divacancies of\nmetal, which in part dissociate and provide a crystal with necessary quantity\nof monovacancies for processes of complex formation. That makes process of\nobtaining of semi-insulating CdZnTe crystals less dependent from pressure Pcd\nin comparison with CdTe. However with the purpose of obtaining CdZnTe crystals\nwith high value of mhth (i.e. with small concentration of the free vacancies of\ncadmium) it is necessary to control Pcd above the crystal at stages of its\ngrowth and annealing."
    },
    {
        "anchor": "PiNNwall: Heterogeneous Electrode Models from Integrating Machine\n  Learning and Atomistic Simulation: Electrochemical energy storage always involves the capacitive process. The\nprevailing electrode model used in the molecular simulation of polarizable\nelectrode-electrolyte systems is the Siepmann-Sprik model developed for perfect\nmetal electrodes. This model has been recently extended to study the\nmetallicity in the electrode by including the Thomas-Fermi screening length.\nNevertheless, a further extension to heterogeneous electrode models requires\nintroducing chemical specificity, which does not have any analytical recipes.\nHere, we address this challenge by integrating the atomistic machine learning\ncode (PiNN) for generating the base charge and response kernel and the\nclassical molecular dynamics code (MetalWalls) dedicated to the modeling of\nelectrochemical systems, and this leads to the development of the PiNNwall\ninterface. Apart from the cases of chemically doped graphene and graphene oxide\nelectrodes as shown in this study, the PiNNwall interface also allows us to\nprobe polarized oxide surfaces in which both the proton charge and the\nelectronic charge can coexist. Therefore, this work opens the door for modeling\nheterogeneous and complex electrode materials often found in energy storage\nsystems.",
        "positive": "Enhanced magneto-transport at high bias in quasi-magnetic tunnel\n  junctions with EuS spin-filter barriers: In quasi-magnetic tunnel junctions (QMTJs) with a EuS spin filter tunnel\nbarrier between Al and Co electrodes, we observed large magnetoresistance (MR).\nThe bias dependence shows an abrupt increase of MR ratio in high bias voltage,\nwhich is contrary to conventional magnetic tunnel junctions (MTJs). This\nbehavior can be understood as due to Fowler-Nordheim tunneling through the\nfully spin-polarized EuS conduction band. The I-V characteristics and bias\ndependence of MR calculated using tunneling theory shows excellent agreement\nwith experiment."
    },
    {
        "anchor": "Bismuth-doping Alters Structural Phase Transitions in Methylammonium\n  Lead Tribromide Single Crystals: We study the effects of bismuth doping on the crystal structure and phase\ntransitions in single crystals of the perovskite semiconductor methylammonium\nlead tribromide, MAPbBr3. By measuring temperature-dependent specific heat\ncapacity (Cp) we find that, as Bi doping increases, the phase transition\nassigned to the cubic to tetragonal phase boundary decreases in temperature.\nFurthermore, after doping we observe one phase transition between 135 and 155\nK, in contrast to two transitions observed in the undoped single crystal. These\nresults appear strikingly similar to previously reported effects of mechanical\npressure on perovskite crystal structure. Using X-ray diffraction, we show that\nthe lattice constant decreases as Bi is incorporated into the crystal, as\npredicted by density functional theory (DFT). We propose that bismuth\nsubstitutional doping on the lead site is dominant, resulting in BiPb+ centers\nwhich induce compressive chemical strain that alters the crystalline phase\ntransitions.",
        "positive": "Energy benchmarks for water clusters and ice structures from an embedded\n  many-body expansion: We show how an embedded many-body expansion (EMBE) can be used to calculate\naccurate \\emph{ab initio} energies of water clusters and ice structures using\nwavefunction-based methods. We use the EMBE described recently by Bygrave\n\\emph{et al.} (J. Chem. Phys. \\textbf{137}, 164102 (2012)), in which the terms\nin the expansion are obtained from calculations on monomers, dimers, etc. acted\non by an approximate representation of the embedding field due to all other\nmolecules in the system, this field being a sum of Coulomb and\nexchange-repulsion fields. Our strategy is to separate the total energy of the\nsystem into Hartree-Fock and correlation parts, using the EMBE only for the\ncorrelation energy, with the Hartree-Fock energy calculated using standard\nmolecular quantum chemistry for clusters and plane-wave methods for crystals.\nOur tests on a range of different water clusters up to the 16-mer show that for\nthe second-order M\\o{}ller-Plesset (MP2) method the EMBE truncated at 2-body\nlevel reproduces to better than 0.1 m$E_{\\rm h}$/monomer the correlation energy\nfrom standard methods. The use of EMBE for computing coupled-cluster energies\nof clusters is also discussed. For the ice structures Ih, II and VIII, we find\nthat MP2 energies near the complete basis-set limit reproduce very well the\nexperimental values of the absolute and relative binding energies, but that the\nuse of coupled-cluster methods for many-body correlation (non-additive\ndispersion) is essential for a full description. Possible future applications\nof the EMBE approach are suggested."
    },
    {
        "anchor": "Energetics of vacancy segregation to symmetric tilt grain boundaries in\n  HCP materials: Molecular static simulations of 190 symmetric tilt grain boundaries in HCP\nmetals were used to understand the energetics of vacancy segregation, which is\nimportant for designing stable interfaces in harsh environments. Simulation\nresults show that the local arrangements of grain boundaries and the resulting\nstructural units have a significant influence on the magnitude of vacancy\nbinding energies, and the site-to-site variation within each boundary is\nsubstantial. Comparing the vacancy binding energies for each site in different\nc/a ratio materials shows that the binding energy increases significantly with\nan increase in c/a ratio. For example, in the [1-210] tilt axis, Ti and Zr with\nc/a=1.5811 have a lower vacancy binding energy than the Mg with c/a=1.6299.\nFurthermore, when the grain boundary energies of all 190 boundaries in all\nthree elements are plotted against the vacancy binding energies of the same\nboundaries, a highly negative correlation (r = -0.7144) is revealed that has a\nlinear fit with a proportionality constant of -25 ang^2. This is significant\nfor applications where extreme environmental damage generates lattice defects\nand grain boundaries act as sinks for both vacancies and interstitial atoms.",
        "positive": "Neural integration for constitutive equations using small data: Data-driven models based on deep learning algorithms intend to overcome the\nlimitations of traditional constitutive modelling by directly learning from\ndata. However, the need for extensive data that collate the full state of the\nmaterial is hindered by traditional experimental observations, which typically\nprovide only small data - sparse and partial material state observations. To\naddress this issue, we develop a novel deep learning algorithm referred to as\nNeural Integration for Constitutive Equations to discover constitutive models\nat the material point level from scarce and incomplete observations. It builds\nupon the solution of the initial value problem describing the time evolution of\nthe material state, unlike the majority of data-driven approaches for\nconstitutive modelling that require large data of increments of state\nvariables. Numerical benchmarks demonstrate that the method can learn accurate,\nconsistent, and robust constitutive models from incomplete, sparse, and noisy\ndata collecting simple conventional experimental protocols."
    },
    {
        "anchor": "Theoretical Proposal for Determining Angular Momentum Compensation in\n  Ferrimagnets: This work demonstrates that the magnetization and angular momentum\ncompensation temperature (TMC and TAMC) in ferrimagnets (FiM) can be\nunambiguously determined by performing two sets of temperature dependent\ncurrent switching, with the symmetry reverses at TMC and TAMC, respectively. A\ntheoretical model based on the modified Landau-Lifshitz-Bloch equation is\ndeveloped to systematically study the spin torque effect under different\ntemperatures, and numerical simulations are performed to corroborate our\nproposal. Furthermore, we demonstrate that the recently reported linear\nrelation between TAMC and TMC can be explained using the Curie-Weiss theory.",
        "positive": "Uncooled Carbon Nanotube Photodetectors: Photodetectors play key roles in many applications such as remote sensing,\nnight vision, reconnaissance, medical imaging, thermal imaging, and chemical\ndetection. Several properties such as performance, reliability, ease of\nintegration, cost, weight, and form factor are all important in determining the\nattributes of photodetectors for particular applications. While a number of\nmaterials have been used over the past several decades to address\nphotodetection needs across the electromagnetic spectrum, the advent of\nnanomaterials opens new possibilities for photodetectors. In particular,\ncarbon-based nanomaterials such as carbon nanotubes (CNTs) and graphene possess\nunique properties that have recently been explored for photodetectors. Here, we\nreview the status of the field, presenting a broad coverage of the different\ntypes of photodetectors that have been realized with CNTs, placing particular\nemphasis on the types of mechanisms that govern their operation. We present a\ncomparative summary of the main performance metrics for such detectors, and an\noutlook for performance improvements."
    },
    {
        "anchor": "A modular table-top setup for ultrafast X-ray diffraction: We present a table-top setup for femtosecond time-resolved X-ray diffraction\nbased on a Cu K{\\alpha} (8.05 keV) laser driven plasma X-ray source. Due to its\nmodular design it provides high accessibility to its individual components\n(e.g. X-ray optics and sample environment). The K{\\alpha}-yield of the source\nis optimized using a pre-pulse scheme. A magnifying multilayer X-ray mirror\nwith Montel-Helios geometry is used to collect the emitted radiation, resulting\nin a quasi-collimated flux of more than 105 Cu K{\\alpha} photons/pulse\nimpinging on the sample under investigation at a repetition rate of 10 Hz. A\ngas ionization chamber detector is placed right after the X-ray mirror and used\nfor normalization of the diffraction signals enabling the measurement of\nrelative signal changes of less than 1% even at the given low repetition rate.\nTime-resolved diffraction experiments on laser-excited epitaxial Bi films serve\nas an example to demonstrate the capabilities of the set-up. The set-up can\nalso be used for Debye-Scherrer type measurements on poly-crystalline samples.",
        "positive": "vdW-DF-ahcx: a range-separated van der Waals density functional hybrid: Hybrid density functionals replace a fraction of an underlying\ngeneralized-gradient approximation (GGA) exchange description with a\nFock-exchange component. Range-separated hybrids (RSHs) also effectively screen\nthe Fock-exchange component and thus open the door for characterizations of\nmetals and adsorption at metal surfaces. The RSHs are traditionally based on a\nrobust GGA, such as PBE [PRL $\\textbf{77}$, 3865 (1996)], for example, as\nimplemented in the HSE design [JPC $\\textbf{118}$, 8207 (2003)]. Here we define\na RSH extension to the van der Waals density functional (vdW-DF) method [ROPP\n$\\textbf{78}$, 066501 (2015)], launching vdW-DF-ahcx. We use an analytical-hole\n(AH) framework [JCP $\\textbf{128}$, 194105 (2008)] to characterize the GGA-type\nexchange in the vdW-DF-cx version [PRB $\\textbf{89}$, 075148 (2014)], isolate\nthe short-ranged exchange component, and define the new RSH. We find that the\nperformance vdW-DF-ahcx compares favorably to (dispersion-corrected) HSE for\ndescriptions of bulk (broad molecular) properties. We also find that it\nprovides accurate descriptions of noble-metal surface properties, including CO\nadsorption."
    },
    {
        "anchor": "Quantum Monte Carlo study of the Ne atom and the Ne+ ion: We report all-electron and pseudopotential calculations of the\nground-stateenergies of the neutral Ne atom and the Ne+ ion using the\nvariational and diffusion quantum Monte Carlo (DMC) methods. We investigate\ndifferent levels of Slater-Jastrow trial wave function: (i) using Hartree-Fock\norbitals, (ii) using orbitals optimized within a Monte Carlo procedure in the\npresence of a Jastrow factor, and (iii) including backflow correlations in the\nwave function. Small reductions in the total energy are obtained by optimizing\nthe orbitals, while more significant reductions are obtained by incorporating\nbackflow correlations. We study the finite-time-step and fixed-node biases in\nthe DMC energy and show that there is a strong tendency for these errors to\ncancel when the first ionization potential (IP) is calculated. DMC gives highly\naccurate values for the IP of Ne at all the levels of trial wave function that\nwe have considered.",
        "positive": "Electronic structure and optical properties of lightweight metal\n  hydrides: We study the electronic structures and dielectric functions of the simple\nhydrides LiH, NaH, MgH2 and AlH3, and the complex hydrides Li3AlH6, Na3AlH6,\nLiAlH4, NaAlH4 and Mg(AlH4)2, using first principles density functional theory\nand GW calculations. All these compounds are large gap insulators with GW\nsingle particle band gaps varying from 3.5 eV in AlH3 to 6.5 eV in the MAlH4\ncompounds. The valence bands are dominated by the hydrogen atoms, whereas the\nconduction bands have mixed contributions from the hydrogens and the metal\ncations. The electronic structure of the aluminium compounds is determined\nmainly by aluminium hydride complexes and their mutual interactions. Despite\nconsiderable differences between the band structures and the band gaps of the\nvarious compounds, their optical responses are qualitatively similar. In most\nof the spectra the optical absorption rises sharply above 6 eV and has a strong\npeak around 8 eV. The quantitative differences in the optical spectra are\ninterpreted in terms of the structure and the electronic structure of the\ncompounds."
    },
    {
        "anchor": "Probing Out-of-Plane Charge Transport in Black Phosphorus with\n  Graphene-Contacted Vertical Field-Effect Transistors: Black phosphorus (BP) has recently emerged as a promising narrow band gap\nlayered semiconductor with optoelectronic properties that bridge the gap\nbetween semi-metallic graphene and wide band gap transition metal\ndichalcogenides such as MoS2. To date, BP field-effect transistors have\nutilized a lateral geometry with in-plane transport dominating device\ncharacteristics. In contrast, we present here a vertical field-effect\ntransistor geometry based on a graphene/BP van der Waals heterostructure. The\nresulting device characteristics include high on-state current densities (>\n1600 A/cm2) and current on/off ratios exceeding 800 at low temperature. Two\ndistinct charge transport mechanisms are identified, which are dominant for\ndifferent regimes of temperature and gate voltage. In particular, the Schottky\nbarrier between graphene and BP determines charge transport at high\ntemperatures and positive gate voltages, whereas tunneling dominates at low\ntemperatures and negative gate voltages. These results elucidate out-of-plane\nelectronic transport in BP, and thus have implications for the design and\noperation of BP-based van der Waals heterostructures.",
        "positive": "Temperature and Humidity Dependence of Resistance in Nano-Diamond Powder: The electrical resistance of detonation nano-diamond powders was measured\nfrom liquid nitrogen temperature to room temperature and in relative humidity\nenvironments from around 10% to 100%. After sample exposures of several hours\nat 100% relative humidity at room temperature (around 295 K), when the\ntemperature was reduced, the resistance increased to the upper measurement\nlimit of our apparatus (120 M{\\Omega}) at around 240 K. Upon warming, the\nresistance dropped back to the room temperature value, with some hysteresis.\nFor sample exposures after several hours at 100% relative humidity at room\ntemperature, as the relative humidity was reduced, the sample resistance\nincreased to the upper range limit of the apparatus. As the relative humidity\nwas then increased (all at room temperature), the resistance dropped. For\nsamples exposed to low (~10%) relative humidity for several hours at room\ntemperature, as the humidity was increased (at room temperature), the\nresistance decreased, and then increased when the humidity was reduced. The\ntemperature behavior was markedly differ from that of powdered graphite and\nmulti-walled carbon nano tubes."
    },
    {
        "anchor": "Exchange interaction for Mn acceptor in GaAs: revealing its strong\n  deformation dependence: In this paper we calculate exchange interaction constant between manganese\nion inner electronic $d$-shell and GaAs valence band bounded hole using their\nmicroscopic multiparticle wave functions. We reveal its parametric dependence\non crystal lattice deformations and find out that it could be about and even\nmore than dozens percent when the strain tensor reaches values of $10^{-3} \\div\n10^{-2}$. This fact is in accordance with the previous hypothesis of\ndeformation dependence of Mn acceptors in GaAs fine energy structure obtained\nfrom Raman spectroscopy, and we show that this dependence has the same\nmagnitude. Also, we resolve here the problem of a substantial high temperature\nmismatch between well-developed theory and experimental data for the static\nmagnetic susceptibility of Mn ions in GaAs. We show by numerical estimates and\ncalculations that quite a strong parametric dependence of the exchange coupling\nvalue on GaAs lattice expansion determines the high temperature (above $50~$K)\nmagnetic susceptibility reduction as well.",
        "positive": "Strain Relaxation in Core-Shell Pt-Co Catalyst Nanoparticles: Surface strain plays a key role in enhancing the activity of Pt-alloy\nnanoparticle oxygen reduction catalysts. However, the details of strain effects\nin real fuel cell catalysts are not well-understood, in part due to a lack of\nstrain characterization techniques that are suitable for complex supported\nnanoparticle catalysts. This work investigates these effects using strain\nmapping with nanobeam electron diffraction and a continuum elastic model of\nstrain in simple core-shell particles. We find that surface strain is relaxed\nboth by lattice defects at the core-shell interface and by relaxation across\nparticle shells caused by Poisson expansion in the spherical geometry. The\ncontinuum elastic model finds that in the absence of lattice dislocations,\ngeometric relaxation results in a surface strain that scales with the average\ncomposition of the particle, regardless of the shell thickness. We investigate\nthe impact of these strain effects on catalytic activity for a series of Pt-Co\ncatalysts treated to vary their shell thickness and core-shell lattice\nmismatch. For catalysts with the thinnest shells, the activity is consistent\nwith an Arrhenius dependence on the surface strain expected for coherent strain\nin dislocation-free particles, while catalysts with thicker shells showed\ngreater activity losses indicating strain relaxation caused by dislocations as\nwell."
    },
    {
        "anchor": "Magnetoresistance and valley degree of freedom in bulk bismuth: In this paper, we first review fundamental aspects of magnetoresistance in\nmulti-valley systems based on the semiclassical theory. Then we will review\nexperimental evidence and theoretical understanding of magnetoresistance in an\narchetypal multi-valley system, where the electric conductivity is set by the\nsum of the contributions of different valleys. Bulk bismuth has three valleys\nwith an extremely anisotropic effective mass. As a consequence, the\nmagnetoconductivity in each valley is extremely sensitive to the orientation of\nthe magnetic field. Therefore, a rotating magnetic field plays the role of a\nvalley valve tuning the contribution of each valley to the total conductivity.\nIn addition to this simple semi-classical effect, other phenomena arise in the\nhigh-field limit as a consequence of an intricate Landau spectrum. In the\nvicinity of the quantum limit, the orientation of magnetic field significantly\naffects the distribution of carriers in each valley, namely, the valley\npolarization is induced by the magnetic field. Moreover, experiment has found\nthat well beyond the quantum limit, one or two valleys become totally empty.\nThis is the only case in condensed-matter physics where a Fermi sea is\ncompletely dried up by a magnetic field without a metal-insulator transition.\nThere have been two long-standing problems on bismuth near the quantum limit:\nthe large anisotropic Zeeman splitting of holes, and the extra peaks in quantum\noscillations, which cannot be assigned to any known Landau levels. These\nproblems are solved by taking into account the interband effect due to the\nspin-orbit couplings for the former, and the contributions from the twinned\ncrystal for the latter. Up to here, the whole spectrum can be interpreted\nwithin the one-particle theory. Finally, we will discuss transport and\nthermodynamic signatures of breaking of the valley symmetry in this system.",
        "positive": "Comment on \"Prediction of lattice constant in cubic perovskites\": In a recent work by Jiang et al. [J. Phys. Chem. Solids 67 (2006) 1531-1536],\nthe interrelationship between lattice constant, ionic radii and tolerance\nfactor of cubic perovskites has been established and an empirical equation was\nobtained. However, the assumption of incorrect ionic coordination led to an\nincorrect mathematical expression even though the average relative errors\nbetween predicted and observed lattice constants of 132 materials were below\n1%. Here, corrected coefficients for that empirical expression are obtained,\nwhich would likely be useful for investigation of general perovskite materials."
    },
    {
        "anchor": "Magnetically enhanced thin film coarsening by a magnetic XPFC model\n  allowing to decouple magnetic anisotropy and magnetostriction: External magnetic fields provide a macroscopic control mechanism to influence\nthe microstructure of polycrystalline materials. We model the influence of\nstrong magnetic fields on grain growth in thin films with a magnetic extended\nphase field crystal (XPFC) model. The magneto-structural effects are\nincorporated into the correlation function in reciprocal space. With this\napproach magnetic anisotropy, magnetostriction and mobility of grain boundary\ncan be controlled and a variety of geometrical and topological properties\nconsistent with experimental results can be determined.",
        "positive": "Experimental evidence of monolayer arsenene: An exotic two-dimensional\n  semiconducting material: Group V element analogues of graphene have attracted a lot attention recently\ndue to their semiconducting band structures, which make them promising for next\ngeneration electronic and optoelectronic devices based on two-dimensional\nmaterials. Theoretical investigations predict high electron mobility, large\nband gaps, band gap tuning by strain, formation of topological phases, quantum\nspin Hall effect at room temperature, and superconductivity amongst others.\nHere, we report a successful formation of freestanding like monolayer arsenene\non Ag(111). This was concluded from our experimental atomic and electronic\nstructure data by comparing to results of our theoretical calculations.\nArsenene forms a buckled honeycomb layer on Ag(111) with a lattice constant of\n3.6 {\\AA} showing an indirect band gap of about 1.4 eV as deduced from the\nposition of the Fermi level pinning."
    },
    {
        "anchor": "Lattice deformation on flat-band modulation in 3D Hopf-linked carbon\n  allotrope: Hopfene: Flat bands form in a 3D Hopf-linked graphene crystal or a 3D carbon allotrope\nnamed Hopfene, which qualitatively differ from bands of only graphenes. This\npaper discusses carbon-hexagon deformation on the level shift of a flat band\nvia density-functional-theoretical (DFT) analysis to set the flat-band level to\nthe Fermi level, viz., to utilize its large density of states for magnetic- and\nelectronic-property researches. Tight-binding (TB) analysis is also performed\nfor a comparison with the DFT analysis; here, a qualitative agreement between\nTB and DFT bands is obtained. The DFT analysis shows an almost linear flat-band\nlevel shift to the lattice-deformation rate, where electron-interaction effects\nare included within the Kohn-Sham method. To tune the flat-band level so that\nit fits the Fermi level, a double-hetero-like structure is also proposed as a\nway of hexagon-deformation control.",
        "positive": "Raman spectroscopy study of pressure-induced phase transitions in single\n  crystal CuInP2S6: Two dimensional ferroic materials exhibit a variety of functional properties\nthat can be tuned by temperature and pressure. CuInP2S6 is a layered material\nthat is ferrielectric at room temperature and whose properties are a result of\nthe unique structural arrangement of ordered Cu and In cations within a P2S6\nanion backbone. Here, we investigate the effect of hydrostatic pressure on the\nstructure of CuInP2S6 single crystals through a detailed Raman spectroscopy\nstudy. Analysis of the peak frequencies, intensities and widths reveals four\nhigh pressure regimes. At 5 GPa the material undergoes a monoclinic-trigonal\nphase transition. At higher pressures (5 - 12 GPa) we see Raman peak\nsharpening, indicative of a change in the electronic structure, followed by an\nincommensurate phase between 12 - 17 GPa. Above 17 GPa we see evidence for\nmetallization in the material. The original state of the material is fully\nrecovered upon decompression, showing that hydrostatic pressure could be used\nto tune the electronic and ferrielectric properties of CuInP2S6."
    },
    {
        "anchor": "Structural and Magnetic Phase Transitions in MnTe-MnSe solid solutions: Neutron diffraction studies as a function of temperature on solid solutions\nof MnSe and MnTe in the Se rich region are presented. Interestingly as Te is\ndoped in MnSe, the structural transformation to NiAs phase diminishes, both in\nterms of \\% fraction of compound as well as in terms of transition temperature.\nIn MnTe$_{0.3}$Se$_{0.7}$, the NaCl to NiAs phase transformation occurs at\nabout 40K and although it is present at room temperature in\nMnTe$_{0.5}$Se$_{0.5}$, its volume fraction is only about 10\\% of the total\nvolume of sample. The magnetic ordering temperature of the cubic phase\ndecreases with increasing Te content while the hexagonal phase orders at the\nsame temperature as in MnSe. Anomalies in thermal evolution of lattice\nparameters at magnetic ordering as well as structural transition temperatures\nindicate presence of magnetostructural coupling in these compounds.",
        "positive": "High Magnetic Field Sensor Using LaSb2: The magnetotransport properties of single crystals of the highly anisotropic\nlayered metal LaSb2 are reported in magnetic fields up to 45 T with fields\noriented both parallel and perpendicular to the layers. Below 10 K the\nperpendicular magnetoresistance of LaSb2} becomes temperature independent and\nis characterized by a 100-fold linear increase in resistance between 0 and 45 T\nwith no evidence of quantum oscillations down to 50 mK. The Hall resistivity is\nhole-like and gives a high field carrier density of n ~ 3x10^20 cm^-3. The\nfeasibility of using LaSb2 for magnetic field sensors is discussed."
    },
    {
        "anchor": "Nuclear magnetic resonance study of thin Co$_2$FeAl$_{0.5}$Si$_{0.5}$\n  Heusler films with varying thickness: Type, degree and evolution of structural order are important aspects for\nunderstanding and controlling the properties of highly spin polarized Heusler\ncompounds, in particular with respect to the optimal film growth procedure. In\nthis work, we compare the structural order and the local magnetic properties\nrevealed by nuclear magnetic resonance (NMR) spectroscopy with the macroscopic\nproperties of thin Co$_2$FeAl$_{0.5}$Si$_{0.5}$ Heusler films with varying\nthickness. A detailed analysis of the measured NMR spectra presented in this\npaper enables us to find a very high degree of $L2_1$ type ordering up to 81%\nconcomitantly with excess Fe of 8 to 13% at the expense of Al and Si. We show,\nthat the formation of certain types of order do not only depend on the\nthermodynamic phase diagrams as in bulk samples, but that the kinetic control\nmay contribute to the phase formation in thin films. It is an exciting finding\nthat Co$_2$FeAl$_{0.5}$Si$_{0.5}$ can form an almost ideal $L2_1$ structure in\nfilms though with a considerable amount of Fe-Al/Si off-stoichiometry.\nMoreover, the very good quality of the films as demonstrated by our NMR study\nsuggests that the novel technique of off-axis sputtering technique used to grow\nthe films sets stage for the optimized performance of\nCo$_2$FeAl$_{0.5}$Si$_{0.5}$ in spintronic devices.",
        "positive": "Light-control of materials via nonlinear phononics: Nonlinear phononics is the phenomenon in which a coherent dynamics in a\nmaterial along a set of phonons is launched after its infrared-active phonons\nare selectively excited using external light pulses. The microscopic mechanism\nunderlying this phenomenon is the nonlinear coupling of the pumped\ninfrared-active mode to other phonon modes present in a material. Nonlinear\nphonon couplings can cause finite time-averaged atomic displacements with or\nwithout broken crystal symmetries depending on the order, magnitude and sign of\nthe nonlinearities. Such coherent lattice displacements along phonon\ncoordinates can be used to control the physical properties of materials and\neven induce transient phases with lower symmetries. Light-control of materials\nvia nonlinear phononics has become a practical reality due to the availability\nof intense mid-infrared lasers that can drive large-amplitude oscillations of\nthe infrared-active phonons of materials. Mid-infrared pump induced\ninsulator-metal transitions and spin and orbital order melting have been\nobserved in pump-probe experiments. First principles based microscopic theory\nof nonlinear phononics has been developed, and it has been used to better\nunderstand how the lattice evolves after a mid-infrared pump excitation of\ninfrared-active phonons. This theory has been used to predict light-induced\nswitching of ferroelectric polarization as well as ferroelectricity in\nparaelectrics and ferromagnetism in antiferromagnets, which have been partially\nconfirmed in recent experiments. This review summarizes the experimental and\ntheoretical developments within this emerging field."
    },
    {
        "anchor": "Ferroelectricity at ferroelectric domain walls: We present a first-principles study of model domain walls (DWs) in prototypic\nferroelectric PbTiO3. At high temperature the DW structure is somewhat trivial,\nwith atoms occupying high- symmetry positions. However, upon cooling the DW\nundergoes a symmetry-breaking transition characterized by a giant dielectric\nanomaly and the onset of a large and switchable polarization. Our results thus\ncorroborate previous arguments for the occurrence of ferroic orders at\nstructural DWs, providing a detailed atomistic picture of a temperature-driven\nDW-confined transformation. Beyond its relevance to the field of\nferroelectrics, our results highlight the interest of these DWs in the broader\nareas of low-dimensional physics and phase transitions in strongly-fluctuating\nsystems.",
        "positive": "Role of structural H$_2$O in intercalation electrodes: the case of Mg in\n  nano-crystalline Xerogel-V$_2$O$_5$: Co-intercalation is a potential approach to influence the voltage and\nmobility with which cations insert in electrodes for energy storage devices.\nCombining a robust thermodynamic model with first-principles calculations, we\npresent a detailed investigation revealing the important role of H$_2$O during\nion intercalation in nano-materials. We examine the scenario of Mg$^{2+}$ and\nH$_2$O co-intercalation in nano-crystalline Xerogel-V$_2$O$_5$, a potential\ncathode material to achieve energy density greater than Li-ion batteries. Water\nco-intercalation in cathode materials could broadly impact an electrochemical\nsystem by influencing its voltages or causing passivation at the anode. The\nanalysis of the stable phases of Mg-Xerogel V$_2$O$_5$ and voltages at\ndifferent electrolytic conditions reveals a range of concentrations for Mg in\nthe Xerogel and H$_2$O in the electrolyte where there is no thermodynamic\ndriving force for H$_2$O to shuttle with Mg during electrochemical cycling.\nAlso, we demonstrate that H$_2$O shuttling with the Mg$^{2+}$ ions in wet\nelectrolytes yields higher voltages than in dry electrolytes. The thermodynamic\nframework used to study water and Mg$^{2+}$ co-intercalation in this work opens\nthe door for studying the general phenomenon of solvent co-intercalation\nobserved in other complex solvent-electrode pairs used in the Li- and Na-ion\nchemical spaces."
    },
    {
        "anchor": "The symmetry and light stuffing of Ho2Ti2O7, Er2Ti2O7 and Yb2Ti2O7\n  characterized by synchrotron X-ray diffraction: The Ho2Ti2O7, Er2Ti2O7 and Yb2Ti2O7 pyrochlores were studied by synchrotron\nX-ray diffraction to determine whether the (002) peak, forbidden in the\npyrochlore space group Fd-3m but observed in single crystal neutron scattering\nmeasurements, is present due to a deviation of their pyrochlore structure from\nFd-3m symmetry. Synchrotron diffraction measurements on precisely synthesized\nstoichiometric and non-stoichiometric powders and a crushed floating zone\ncrystal of Ho2Ti2O7 revealed that the (002) reflection is absent in all cases\nto a sensitivity of approximately one part in 30,000 of the strongest X-ray\ndiffraction peak. This indicates to high sensitivity that the structural space\ngroup of these rare earth titanate pyrochlores is Fd-3m, and that thus the\n(002) peak observed in the neutron scattering experiments has a non-structural\norigin. The cell parameters and internal strain for lightly stuffed\nHo2+xTi2-xO7 are also presented.",
        "positive": "Conduction mechanisms of epitaxial EuTiO3 thin films: To investigate leakage current density versus electric field characteristics,\nepitaxial EuTiO3 thin films were deposited on (001) SrTiO3 substrates by pulsed\nlaser deposition and were post-annealed in a reducing atmosphere. This\ninvestigation found that conduction mechanisms are strongly related to\ntemperature and voltage polarity. It was determined that from 50 to 150 K the\ndominant conduction mechanism was a space-charge-limited current under both\nnegative and positive biases. From 200 to 300 K, the conduction mechanism shows\nSchottky emission and Fowler-Nordheim tunneling behaviors for the negative and\npositive biases, respectively. This work demonstrates that Eu3+ is one source\nof leakage current in EuTiO3 thin films."
    },
    {
        "anchor": "Ab initio investigation of the AlN:Er system: In the present study an ab initio investigation on the AlN:Er system for\nconcentrations of Er ranging from 0.78 to 12.5 % is presented. The\ncrystallographic localisation of the rare earth atoms in the wurtzite lattice\nis determined, elucidating previously published experimental deductions, and\nthe existence of a solid solution in the AlN:Er system in this range is\nconfirmed. Er incorporation in the tetrahedral and octahedral insertion sites\nis shown to be thermodynamically metastable and is found to induce shallow\nstates in the bandgaps. The effect of Er concentration on the lattice constants\nand bandgaps and bandstructures of the ErxAl1-xN ternary compound is presented.\nFinally, in accordance with experimental specifications, Er incorporation in\nthe AlNO system is also examined.",
        "positive": "Electrodynamics of magnetoelectric media and magnetoelectric fields: The relationship between magnetoelectricity and electromagnetism is a subject\nof a strong interest and numerous discussions in microwave and optical wave\nphysics and material sciences. The definition of the energy and momentum of the\nelectromagnetic (EM) field in a magnetoelectric (ME) medium is not a trivial\nproblem. The question of whether electromagnetism and magnetoelectricity can\ncoexist without an extension of Maxwell theory arises when we study the effects\nof EM energy propagation and consider group velocity of the waves in a ME\nmedium. The energy balance equation reveals unusual topological structure of\nfields in ME materials. Together with certain constraints on the constitutive\nparameters of a medium, definite constraints on the local field structure\nshould be imposed. Analyzing the EM phenomena inside a ME material, we should\nanswer the question: what kind of the near fields arising from a sample of such\na material can we measure? Visualization of the ME states requires an\nexperimental technique that is based on an effective coupling to the violation\nof spatial as well as temporal inversion symmetry. To observe the ME energy in\na subwavelength region, it is necessary to assume the existence of first\nprinciple near fields, the ME fields. These are non Maxwellian near fields with\nspecific properties of violation of spatial and temporal inversion symmetry. A\nparticular interest to the ME fields arises in studies of metamaterials with\nartificial atoms ME elements."
    },
    {
        "anchor": "A local-density approximation for the exchange energy functional for\n  excited states : the band gap problem: We present excited states density functional theory (DFT) to calculate band\ngap for semiconductors and insulators. For the excited states\nexchange-correlation functional, we use a simple local density approximation\n(LDA) like functional and it gives the result which is very closed to\nexperimental results. The linear muffin-tin potential is used to solve the self\nconsistent Kohn-Sham equation",
        "positive": "Spider-Web Inspired Mechanical Metamaterials: Spider silk is a remarkable example of bio-material with superior mechanical\ncharacteristics. Its multilevel structural organization of dragline and viscid\nsilk leads to unusual and tunable properties, extensively studied from a\nquasi-static point of view. In this study, inspired by the Nephila spider orb\nweb architecture, we propose a novel design for mechanical metamaterials based\non its periodic repetition. We demonstrate that spider-web metamaterial\nstructure plays an important role in the dynamic response and wave attenuation\nmechanisms. The capability of the resulting structure to inhibit elastic wave\npropagation in sub-wavelength frequency ranges is assessed and parametric\nstudies are performed to derive optimal configurations and constituent\nmechanical properties. The results show promise for the design of innovative\nlightweight structures for tunable vibration damping and impact protection, or\nthe protection of large scale infrastructure such as suspended bridges."
    },
    {
        "anchor": "Nonequilibrium grain size distribution with generalized growth and\n  nucleation rates: We determine the non-equilibrium grain size distribution during the\ncrystallization of a solid in $d$ dimensions at fixed thermodynamic conditions,\nfor the random nucleation and growth model, and in absence of grain\ncoalescence. Two distinct generalizations of the theory established earlier are\nconsidered. A closed analytic expression of the grain size distribution useful\nfor experimental studies is derived for anisotropic growth rates. The main\ndifference from the isotropic growth case is the appearance of a constant\nprefactor in the distribution. The second generalization considers a Gaussian\nsource term: nuclei are stable when their volume is within a finite range\ndetermined by the thermodynamics of the crystallization process. The numerical\nresults show that this generalization does not change the qualitative picture\nof our previous study. The generalization only affects quantitatively the early\nstage of crystallization, when nucleation is dominant. The remarkable result of\nthese major generalizations is that the non-equilibrium grain size distribution\nis robust against anisotropic growth of grains and fluctuations of nuclei\nsizes.",
        "positive": "Evidence for Higher order topology in Bi and Bi$_{0.92}$Sb$_{0.08}$: Higher order topological insulators (HOTIs) are a new class of topological\nmaterials which host protected states at the corners or hinges of a crystal.\nHOTIs provide an intriguing alternative platform for helical and chiral edge\nstates and Majorana modes, but there are very few known materials in this\nclass. Recent studies have proposed Bi as a potential HOTI, however, its\ntopological classification is not yet well accepted. In this work, we show that\nthe (110) facets of Bi and BiSb alloys can be used to unequivocally establish\nthe topology of these systems. Bi and Bi$_{0.92}$Sb$_{0.08}$ (110) films were\ngrown on silicon substrates using molecular beam epitaxy and studied by\nscanning tunneling spectroscopy. The surfaces manifest rectangular islands\nwhich show localized hinge states on three out of the four edges, consistent\nwith the theory for the HOTI phase. This establishes Bi and\nBi$_{0.92}$Sb$_{0.08}$ as HOTIs, and raises questions about the topological\nclassification of the full family of Bi$_{x}$Sb$_{1-x}$ alloys."
    },
    {
        "anchor": "Second generation wave-function thermostat for ab-initio molecular\n  dynamics: A rigorous two-thermostat formulation for ab-initio molecular dynamics using\nthe fictitious Lagrangian approach is presented. It integrates the concepts of\nmass renormalization and temperature control for the wave functions. The new\nthermostat adapts to the instantaneous kinetic energy of the nuclei and thus\nminimizes its influence on the dynamics. Deviations from the canonical\nensemble, which are possible in the previous two-thermostat formulation, are\navoided. The method uses a model for the effective mass of the wave functions,\nwhich is open to systematic improvement.",
        "positive": "Low temperature transport properties of multigraphene structures on\n  6H-SiC obtained by thermal graphitization: evidences of a presence of nearly\n  perfect graphene layer: Transport properties of multigraphene layers on 6H-SiC substrates fabricated\nby thermal graphitization of SiC were studied. The principal result is that\nthese structures were shown to contain a nearly perfect graphene layer situated\nbetween the SiC substrate and multgraphene layer. It was found that the curves\nof magnetoresistance and Shubnikov- de Haas oscillations shown the features,\ntypical for single-layered graphene. The low temperature resistance\ndemonstrated an increase with temperature increase, which also corresponds to a\nbehavior typical for single-layered graphene (antilocalization). However at\nhigher temperatures the resistance decreased with an increase of temperature,\nwhich corresponds to a weak localization. We believe that the observed behavior\ncan be explained by a parallel combination of contributions to the conductivity\nof single-layered graphene and of multigraphene, the latter allowing to escape\ndamages of the graphene by atmosphere effect."
    },
    {
        "anchor": "A Framework for Ductility in Metallic Glasses: The understanding and quantification of ductility in crystalline metals,\nwhich has led to their widespread and effective usage as a structural material,\nis lacking in metallic glasses (MGs). Here, we introduce such a framework for\nductility. This very practical framework is based on a MGs ability to support\nstable shear band growth, quantified in a stress gradient, gradSDB, which we\nmeasure and calculate for a range of MGs. Whether a MG behaves ductile or\nbrittle in an application is determined by the comparison between gradsDB the\napplied stress field gradient, gradsapp. If gradsDB > gradsapp, the MG will\nbehave brittle, if gradsDB < gradsapp, the MG will behave ductile, and gradsapp\n- gradsDB indicates how ductile. This framework can explain observed plastic\nproperties of MGs and their apparent contradicting brittle and ductile\ncharacteristics. Looking forward, proposed framework provides the constitutive\nrelation to quantitatively model their plastic behavior in any application, a\nrequirement to use MGs as structural materials.",
        "positive": "Photovoltaic effect in BiFeO3/TiO2 heterostructures tuned with epitaxial\n  strain and an electric field: The photovoltaic effect in the BiFeO3/TiO2 heterostructures can be tuned by\nepitaxial strain and an electric field in the visible-light region which is\nmanifested by the enhancement of absorption activity in the heterojunction\nunder tensile strain and an electric field based on the first-principles\ncalculations. It is suggested that there are coupling between photon, spin\ncarrier, charge, orbital, and lattice in the interface of the bilayer film\nwhich makes the heterojunction an intriguing candidate towards fabricating the\nmultifunctional photoelectric devices based on spintronics. The microscopic\nmechanism involved in the heterostruces is related deeply with the spin\ntransfer and charge rearrangement between the Fe 3d and O 2p orbitals in the\nvicinity of the interface."
    },
    {
        "anchor": "C60+C60 molecular bonding revisited and expanded: Several dimerization products of fullerene C60 are presented and thoroughly\ncharacterized with a quantum chemical DFT model augmented by dispersion. We\nreanalyze and expand significantly the number of known dimers from 12 to 41.\nMany of the novel bonding schemes were found by analyzing more than 2\nnanoseconds of high energy molecular dynamics semiempirical trajectories with\nAutoMeKin, a methodology previously used to compute the reactivity of much\nsmaller molecules. For completeness, this was supplemented by structures built\nby different geometric considerations. Also, spin-polarization was explicitly\nconsidered yielding 12 new bonding schemes with magnetic ground states. The\nresults are comprehensively analyzed and discussed in the context of yet to be\nexplained 3D fullerene structures and recent fullerene 2D systems.",
        "positive": "Metastability in pressure-induced structural transformations of CdSe/ZnS\n  core/shell nanocrystals: The kinetics and thermodynamics of structural transformations under pressure\ndepend strongly on particle size due to the influence of surface free energy.\nBy suitable design of surface structure, composition, and passivation it is\npossible, in principle, to prepare nanocrystals in structures inaccessible to\nbulk materials. However, few realizations of such extreme size-dependent\nbehavior exist. Here we show with molecular dynamics computer simulation that\nin a model of CdSe/ZnS core/shell nanocrystals the core high pressure structure\ncan be made metastable under ambient conditions by tuning the thickness of the\nshell. In nanocrystals with thick shells, we furthermore observe a wurtzite to\nNiAs transformation, which does not occur in the pure bulk materials. These\nphenomena are linked to a fundamental change in the atomistic transformation\nmechanism from heterogenous nucleation at the surface to homogenous nucleation\nin the crystal core. Our results suggest a new route towards expanding the\nrange of available nanoscale materials."
    },
    {
        "anchor": "Structural Aspects of Deformation Defects in Bulk Metallic Glasses: Mechanical behaviors of bulk metallic glasses (BMGs) including heterogeneous\nand homogeneous deformation are interpreted by phenomenological shear\ntransformation zones (STZs) model. Currently, information about STZs, i.e. size\nand density, is only extracted by fitting model equation to the data obtained\nfrom macroscopic mechanical tests. This is inadequate since structural features\nof STZs theory cannot be assessed. Here, we develop anisotropic pair\ndistribution function (PDF) method for directly characterizing mechanical\nresponse of deformation defects. Our results reveal the physical picture of\ndeformation defects in BMGs and also provide direct experimental observation of\na link between mechanical deformation and intrinsic properties of deformation\ndefects in BMGs.",
        "positive": "Polaronic contributions to oxidation and hole conductivity in\n  acceptor-doped BaZrO$_3$: Acceptor-doped perovskite oxides like BaZrO$_3$ are showing great potential\nas materials for renewable energy technologies where hydrogen acts an energy\ncarrier, such as solid oxide fuel cells and hydrogen separation membranes.\nWhile ionic transport in these materials has been investigated intensively, the\nelectronic counterpart has received much less attention and further exploration\nin this field is required. Here, we use density functional theory (DFT) to\nstudy hole polarons and their impact on hole conductivity in Y-doped BaZrO$_3$.\nThree different approaches have been used to remedy the self-interaction error\nof local and semi-local exchange-correlation functionals: DFT$+U$, pSIC-DFT and\nhybrid functionals. Self-trapped holes are found to be energetically favorable\nby about $-$0.1 eV and the presence of yttrium results in further\nstabilization. Polaron migration is predicted to occur through intraoctahedral\ntransfer and polaron rotational processes, which are associated with adiabatic\nbarriers of about 0.1 eV. However, the rather small energies associated with\npolaron formation and migration suggest that the hole becomes delocalized and\nband-like at elevated temperatures. These results together with an endothermic\noxidation reaction [A. Lindman et al., Phys. Rev. B 91, 245114 (2015)] yield a\npicture that is consistent with experimental data for the hole conductivity.\nThe results we present here provide new insight into hole transport in\nacceptor-doped BaZrO$_3$ and similar materials, which will be of value in the\nfuture development of sustainable technologies."
    },
    {
        "anchor": "Phonon Softening and Direct to Indirect Bandgap Crossover in Strained\n  Single Layer MoSe2: Motivated by recent experimental observations of Tongay et al. [Tongay et\nal., Nano Letters, 12(11), 5576 (2012)] we show how the electronic properties\nand Raman characteristics of single layer MoSe2 are affected by elastic biaxial\nstrain. We found that with increasing strain: (1) the E' and E\" Raman peaks\n(E1g and E2g in bulk) exhibit significant red shifts (up to 30 cm-1), (2) the\nposition of the A1' peak remains at 180 cm-1 (A1g in bulk) and does not change\nconsiderably with further strain, (3) the dispersion of low energy flexural\nphonons crosses over from quadratic to linear and (4) the electronic band\nstructure undergoes a direct to indirect bandgap crossover under 3% biaxial\ntensile strain. Thus the application of strain appears to be a promising\napproach for a rapid and reversible tuning of the electronic, vibrational and\noptical properties of single layer MoSe2 and similar MX2 dichalcogenides.",
        "positive": "Confined dipole and exchange spin waves in a bulk chiral magnet with\n  Dzyaloshinskii-Moriya interaction: The Dzyaloshinskii-Moriya interaction (DMI) has an impact on excited spin\nwaves in the chiral magnet Cu$_2$OSeO$_3$ by means of introducing asymmetry on\ntheir dispersion relations. The confined eigenmodes of a chiral magnet are\nhence no longer the conventional standing spin waves. Here we report a combined\nexperimental and micromagnetic modeling study by broadband microwave\nspectroscopy we observe confined spin waves up to eleventh order in bulk\nCu$_2$OSeO$_3$ in the field-polarized state. In micromagnetic simulations we\nfind similarly rich spectra. They indicate the simultaneous excitation of both\ndipole- and exchange-dominated spin waves with wavelengths down to (47.2 $\\pm$\n0.05) nm attributed to the exchange interaction modulation. Our results suggest\nDMI to be effective to create exchange spin waves in a bulk sample without the\nchallenging nanofabrication and thereby to explore their scattering with\nnoncollinear spin textures."
    },
    {
        "anchor": "Mechanism of spin crossover in LaCoO3 resolved by shape magnetostriction\n  in pulsed magnetic fields: In the scientific description of unconventional transport properties of\noxides (spin-dependent transport, superconductivity etc.), the spin-state\ndegree of freedom plays a fundamental role. Because of this, temperature- or\nmagnetic field-induced spin-state transitions are in the focus of solid-state\nphysics. Cobaltites, e.g. LaCoO3, are prominent examples showing these spin\ntransitions. However, the microscopic nature of the spontaneous spin crossover\nin LaCoO3 is still controversial. Here we report magnetostriction measurements\non LaCoO3 in magnetic fields up to 70 T to study the sharp, field-induced\ntransition at Hc ~ 60 T. Measurements of both longitudinal and transversal\nmagnetostriction allow us to separate magnetovolume and magnetodistortive\nchanges. We find a large increase in volume, but only a very small increase in\ntetragonal distortion at Hc. The results, supported by electronic energy\ncalculations by the configuration interaction cluster method, provide\ncompelling evidence that above Hc LaCoO3 adopts a correlated low spin/high spin\nstate.",
        "positive": "On the elastic moduli of two-dimensional assemblies of disks: relevance\n  and modeling of fluctuations in particle displacements and rotations: We determine the elastic moduli of two-dimensional assemblies of disks by\ncomputer simulations. The disks interact through elastic contact forces, that\noppose the relative displacement at the contact points by means of a normal and\na tangential stiffness, both taken constant. Our simulations confirm that the\nuniform strain assumption results in inaccurate predictions of the elastic\nmoduli, since large fluctuations in particle displacements and rotations occur.\nWe phrase their contribution in terms of the relative displacement they induce\nat the contact points. We show that the fluctuations that determine the\nequivalent continuum behavior depend on the average geometry of the assembly.\nWe further separate the contributions from the center displacement and the\nparticle rotation. The fluctuations result in a relaxation of the system, but\nalong the tangential direction the relaxation is generally entirely due to\nrotations. We consider two theoretical formulations for predicting the elastic\nmoduli that include the fluctuations, namely the ``pair-fluctuation'' and the\n``particle-fluctuation'' method. They are both based on the equilibrium of a\nsmall subassembly, which is considered representative of the average structure.\nWe investigate the corresponding predictions of the elastic moduli over a range\nof coordination numbers and of ratios between tangential and normal stiffness.\nWe find a significant improvement with respect to the uniform strain theory.\nFurthermore, the dependence of the fluctuations on coordination number and\nratio of tangential to normal stiffness is qualitatively captured."
    },
    {
        "anchor": "The exact solution of the diffusion trapping model of defect profiling\n  with variable energy positrons: We report an exact analytical solution of so-called positron diffusion\ntrapping model. This model have been widely used for the treatment of the\nexperimental data for defect profiling of the adjoin surface layer using the\nvariable energy positron (VEP) beam technique. Hovewer, up to now this model\ncould be treated only numerically with so-called VEPFIT program. The explicit\nform of the solutions is obtained for the realistic cases when defect profile\nis described by a discreet step-like function and continuous exponential-like\nfunction. Our solutions allow to derive the analytical expressions for typical\npositron annihilation characteristics including the positron lifetime spectrum.\nLatter quantity could be measured using the pulsed, slow positron beam. Our\nanalytical results are in good coincidence with both the VEPFIT numerics and\nexperimental data. The presented solutions are easily generalizable for defect\nprofiles of other shapes and can be well used for much more precise treatment\nof above experimental data.",
        "positive": "Machine-learned metrics for predicting the likelihood of success in\n  materials discovery: Materials discovery is often compared to the challenge of finding a needle in\na haystack. While much work has focused on accurately predicting the properties\nof candidate materials with machine learning (ML), which amounts to evaluating\nwhether a given candidate is a piece of straw or a needle, less attention has\nbeen paid to a critical question: Are we searching in the right haystack? We\nrefer to the haystack as the design space for a particular materials discovery\nproblem (i.e. the set of possible candidate materials to synthesize), and thus\nframe this question as one of design space selection. In this paper, we\nintroduce two metrics, the Predicted Fraction of Improved Candidates (PFIC),\nand the Cumulative Maximum Likelihood of Improvement (CMLI), which we\ndemonstrate can identify discovery-rich and discovery-poor design spaces,\nrespectively. Using CMLI and PFIC together to identify optimal design spaces\ncan significantly accelerate ML-driven materials discovery."
    },
    {
        "anchor": "Fast diffusion of a Lennard-Jones cluster on a crystalline surface: We present a Molecular Dynamics study of large Lennard-Jones clusters\nevolving on a crystalline surface. The static and the dynamic properties of the\ncluster are described. We find that large clusters can diffuse rapidly, as\nexperimentally observed. The role of the mismatch between the lattice\nparameters of the cluster and the substrate is emphasized to explain the\ndiffusion of the cluster. This diffusion can be described as a Brownian motion\ninduced by the vibrationnal coupling to the substrate, a mechanism that has not\nbeen previously considered for cluster diffusion.",
        "positive": "The Effect of Electrical Boundary Conditions on the Thermal Properties\n  of Ferroelectric Piezoelectric Ceramics: The thermal conductivity of polycrystalline bulk PZT\n(lead-zirconate-titanate) has been investigated according to electrical\nboundary conditions and poling. The thermal conductivity of poled PZT was\nmeasured in the poling direction for open circuit and short circuit conditions.\nThe short circuit thermal conductivity had the largest thermal conductivity.\nThe relationship between these two thermal properties, the electrothermal\ncoupling factor $k_{33}^{\\kappa}$, was found to be similar to the\nelectromechanical coupling factor $k_{33}$ relating elastic compliance under\nshort circuit and open circuit conditions. The thermal conductivity of the\nunpoled sample was found to have the lowest thermal conductivity. The\nsignificance of the thermal conductivity with regards to phonon mode scattering\nand elastic compliance was discussed."
    },
    {
        "anchor": "Nonmonotonic particle-size-dependence of magnetoelectric coupling in\n  strained nanosized particles of BiFeO$_3$: Using high resolution powder x-ray and neutron diffraction experiments, we\ndetermined the off-centered displacement of the ions within a unit cell and\nmagnetoelectric coupling in nanoscale BiFeO$_3$ ($\\approx$20-200 nm). We found\nthat both the off-centered displacement of the ions and magnetoelectric\ncoupling exhibit nonmonotonic variation with particle size. They increase as\nthe particle size reduces from bulk and reach maximum around 30 nm. With\nfurther decrease in particle size, they decrease precipitously. The\nmagnetoelectric coupling is determined by the anomaly in off-centering of ions\naround the magnetic transition temperature ($T_N$). The ions, in fact, exhibit\nlarge anomalous displacement around the $T_N$ which is analyzed using group\ntheoretical approach. It underlies the nonmonotonic particle-size-dependence of\noff-centre displacement of ions and magnetoelectric coupling. The nonmonotonic\nvariation of magnetoelectric coupling with particle size is further verified by\ndirect electrical measurement of remanent ferroelectric hysteresis loops at\nroom temperature under zero and $\\sim$20 kOe magnetic field. Competition\nbetween enhanced lattice strain and compressive pressure appears to be causing\nthe nonmonotonic particle-size-dependence of off-centre displacement while\ncoupling between piezo and magnetostriction leads to nonmonotonicity in the\nvariation of magnetoelectric coupling.",
        "positive": "Ultrafast optical nanoscopy of carrier dynamics in silicon nanowires: Carrier distribution and dynamics in semiconductor materials often govern\ntheir physical properties that are critical to functionalities and performance\nin industrial applications. The continued miniaturization of electronic and\nphotonic devices calls for tools to probe carrier behavior in semiconductors\nsimultaneously at the picosecond time and nanometer length scales. Here, we\nreport pump-probe optical nanoscopy in the visible-near-infrared spectral\nregion to characterize the carrier dynamics in silicon nanostructures. By\ncoupling experiments with the point-dipole model, we resolve the size-dependent\nphotoexcited carrier lifetime in individual silicon nanowires. We further\ndemonstrate local carrier decay time mapping in silicon nanostructures with a\nsub-50 nm spatial resolution. Our study enables the nanoimaging of ultrafast\ncarrier kinetics, which will find promising applications in the future design\nof a broad range of electronic, photonic, and optoelectronic devices."
    },
    {
        "anchor": "Non-collinear Korringa-Kohn-Rostoker Green function method: Application\n  to 3d nanostructures on Ni(001): Magnetic nanostructures on non-magnetic or magnetic substrates have attracted\nstrong attention due to the development of new experimental methods with atomic\nresolution. Motivated by this progress we have extended the full-potential\nKorringa-Kohn-Rostoker (KKR) Green function method to treat non-collinear\nmagnetic nanostructures on surfaces. We focus on magnetic 3d impurity\nnanoclusters, sitting as adatoms on or in the first surface layer on Ni(001),\nand investigate the size and orientation of the local moments and moreover the\nstabilization of non-collinear magnetic solutions. While clusters of Fe, Co, Ni\natoms are magnetically collinear, non-collinear magnetic coupling is expected\nfor Cr and Mn clusters on surfaces of elemental ferromagnets. The origin of\nfrustration is the competition of the antiferromagnetic exchange coupling among\nthe Cr or Mn atoms with the antiferromagnetic (for Cr) or ferromagnetic (for\nMn) exchange coupling between the impurities and the substrate. We find that Cr\nand Mn first-neighbouring dimers and a Mn trimer on Ni(001) show non-collinear\nbehavior nearly degenerate with the most stable collinear configuration.\nIncreasing the distance between the dimer atoms leads to a collinear behavior,\nsimilar to the one of the single impurities. Finally, we compare some of the\nnon-collinear {\\it ab-initio} results to those obtained within a classical\nHeisenberg model, where the exchange constants are fitted to total energies of\nthe collinear states; the agreement is surprisingly good.",
        "positive": "Giant thermoelectric power factor anisotropy in PtSb$_{1.4}$Sn$_{0.6}$: We report giant anisotropy in thermoelectric power factor ($S^2\\sigma$) of\nmarcasite structure-type PtSb$_{1.4}$Sn$_{0.6}$. PtSb$_{1.4}$Sn$_{0.6}$,\nsynthesized using ambient pressure flux growth method upon mixing Sb and Sn on\nthe same atomic site, is a new phase different from both PtSb$_2$ and PtSn$_2$\nthat crystallize in the cubic $Pa\\bar{3}$ pyrite and $Fm\\bar{3}m$ fluorite unit\ncell symmetry, respectively. Giant difference in $S^2\\sigma$ for heat flow\napplied along different principal directions of the orthorhombic unit cell\nmostly stems from anisotropic Seebeck coefficients."
    },
    {
        "anchor": "Hidden spin-orbital hexagonal ordering induced by strong correlations in\n  LiVS$_2$: We present a first-principles many-body analysis of multi-orbital lattice\nsusceptibilities in the metallic phase of the quasi-twodimensional compound\nLiVS$_2$. We base this on advanced correlated electronic structure methods for\nthe $t_{2g}$-shell to reveal a highly entangled spin-orbital hexagonal ordering\n(SOHO) bringing about an inherently intersite order parameter for the\ntrimerization transition, which eventually leads to an intriguing insulating\nphase at low temperature.",
        "positive": "Intrinsic Spin Seebeck Effect in Au/YIG: The acute magnetic proximity effects in Pt/YIG compromise the suitability of\nPt as a spin current detector. We show that Au/YIG, with no anomalous Hall\neffect and a negligible magnetoresistance, allows the measurements of the\nintrinsic spin Seebeck effect with a magnitude much smaller than that in\nPt/YIG. The experiment results are consistent with the spin-polarized\ndensity-functional calculations for Pt with a sizable and Au with a negligible\nmagnetic moment near the interface with YIG."
    },
    {
        "anchor": "Diffusion of Small Molecules in Metal Organic Framework Materials: Ab initio simulations are combined with in situ infrared spectroscopy to\nunveil the molecular transport of H$_2$, CO$_2$, and H$_2$O in the metal\norganic framework MOF-74-Mg. Our study uncovers---at the atomistic level---the\nmajor factors governing the transport mechanism of these small molecules. In\nparticular, we identify four key diffusion mechanisms and calculate the\ncorresponding diffusion barriers, which are nicely confirmed by time-resolved\ninfrared experiments. We also answer a long-standing question about the\nexistence of secondary adsorption sites for the guest molecules, and we show\nhow those sites affect the macroscopic diffusion properties. Our findings are\nimportant to gain a fundamental understanding of the diffusion processes in\nthese nano-porous materials, with direct implications for the usability of MOFs\nin gas sequestration and storage applications.",
        "positive": "Strain engineering in single-, bi- and tri-layer MoS2, MoSe2, WS2 and\n  WSe2: Strain is a powerful tool to modify the optical properties of semiconducting\ntransition metal dichalcogenides like MoS2, MoSe2, WS2 and WSe2. In this work\nwe provide a thorough description of the technical details to perform uniaxial\nstrain measurements on these two-dimensional semiconductors and we provide a\nstraightforward calibration method to determine the amount of applied strain\nwith high accuracy. We then employ reflectance spectroscopy to analyze the\nstrain tunability of the electronic properties of single-, bi- and tri-layer\nMoS2, MoSe2, WS2 and WSe2. Finally, we quantify the flake-to-flake variability\nby analyzing 15 different single-layer MoS2 flakes."
    },
    {
        "anchor": "Thermo-magnetic properties of the magnetocaloric layered materials based\n  upon FeMnAsP: a Green function-method approach: The compounds FeMnAsxP1-x are very promising as far as commercial\napplications of the magnetocaloric effect are concerned. However, the\ntheoretical literature on magnetocaloric materials still adopts simple\nmolecular-field models in the description of important properties like the\nentropy variation that accompanies applied isothermal magnetic field cycling,\nfor instance. We apply a Green function theoretical treatment for such\nanalysis. The advantages of such approach are well-known since the details of\nthe crystal structure are incorporated in the model, as well as a precise\ndescription of correlations between spins of the transition metal ions can be\nobtained. For the sake of simplcity we adopt a simple one-exchange parameter\nHeisenberg model, and the observed first-order phase transitions are reproduced\nby the introduction of a biquadratic term in the hamiltonian. Good agreement\nwith experimental magnetocaloric data for FeMnAsxP1-x compounds is obtained, as\nwell as an agreement with the magnetic field dependence for these properties\npredicted from the Landau theory of continuous phase transitions.",
        "positive": "Semiconductor Nanowire Light Emitting Diodes Grown on Metal: A Direction\n  towards Large Scale Fabrication of Nanowire Devices: Bottom up nanowires are attractive for realizing semiconductor devices with\nextreme heterostructures because strain relaxation through the nanowire\nsidewalls allows the combination of highly lattice mismatched materials without\ncreating dislocations. The resulting nanowires are used to fabricate light\nemitting diodes (LEDs), lasers, solar cells and sensors. However, expensive\nsingle crystalline substrates are commonly used as substrates for nanowire\nheterostructures as well as for epitaxial devices, which limits the\nmanufacturability of nanowire devices. Here, we demonstrate nanowire LEDs\ndirectly grown and electrically integrated on metal. Optical and structural\nmeasurements reveal high-quality, vertically-aligned GaN nanowires on\nmolybdenum and titanium films. Transmission electron microscopy confirms the\ncomposition variation in the polarization-graded AlGaN nanowire LEDs. Blue to\ngreen electroluminescence is observed from InGaN quantum well active regions,\nwhile GaN active regions exhibit ultraviolet emission. These results\ndemonstrate a pathway for large-scale fabrication of solid state lighting and\noptoelectronics on metal foils or sheets."
    },
    {
        "anchor": "Tuning the Interlayer Microstructure and Residual Stress of Buffer-Free\n  Direct Bonding GaN/Si Heterostructures: The direct integration of GaN with Si can boost great potential for low-cost,\nlarge-scale, and high-power device applications. However, it is still\nchallengeable to directly grow GaN on Si without using thick strain relief\nbuffer layers due to their large lattice and thermal-expansion-coefficient\nmismatches. In this work, a GaN/Si heterointerface without any buffer layer is\nsuccessfully fabricated at room temperature via surface activated bonding\n(SAB). The residual stress states and interfacial microstructures of GaN/Si\nheterostructures were systematically investigated through micro-Raman\nspectroscopy and transmission electron microscopy. Compared to the large\ncompressive stress that existed in GaN layers grown-on-Si by MOCVD, a\nsignificantly relaxed and uniform small tensile stress was observed in GaN\nlayers bonded-to-Si by SAB; this is mainly ascribed to the amorphous layer\nformed at the bonding interface. In addition, the interfacial microstructure\nand stress states of bonded GaN/Si heterointerfaces was found can be\nsignificantly tuned by appropriate thermal annealing. This work moves an\nimportant step forward directly integrating GaN to the present Si CMOS\ntechnology with high quality thin interfaces, and brings great promises for\nwafer-scale low-cost fabrication of GaN electronics.",
        "positive": "Triply degenerate nodal lines in topological and non-topological metals: Topological nodal-line semimetals exhibit double or fourfold degenerate nodal\nlines, which are protected by symmetries. Here, we investigate the possibility\nof the existence of triply degenerate nodal lines in metals. We present two\ntypes of triply degenerate nodal lines, one topologically trivial and the other\nnontrivial. The first type is stacked by two-dimensional pseudospin-1 fermions,\nwhich can be viewed as an critical case of a tunable band-crossing line\nstructure that contains a symmetry-protected quadratic band-crossing line and a\nnon-degenerate band, and can split into four Weyl nodal lines under\nperturbations. We find that surface states of the nodal line structure are\ndependent on the geometry of the lattice and the surface termination. Such a\nmetal has a nesting of Fermi surface in a range of filling, resulting in a\ndensity-wave state when interaction is included. The second type is a vortex\nring of pseudospin-1 fermions. In this system, the pseudospins form Skyrmion\ntextures, and the surface states are fully extended topological Fermi arcs so\nthat the model exhibits 3D quantum anomalous Hall effect with a maximal Hall\nconductivity. The vortex ring can evolve into a pair of vortex lines that are\nnot closed in the first Brillouin zone. A vortex line cannot singly exist in\nthe lattice model if it is the only nodal feature of the system."
    },
    {
        "anchor": "Mirrors for slow neutrons from holographic nanoparticle-polymer\n  free-standing film-gratings: We report on successful tests of holographically arranged grating-structures\nin nanoparticle-polymer composites in the form of 100 microns thin\nfree-standing films, i.e. without sample containers or covers that could cause\nunwanted absorption/incoherent scattering of very-cold neutrons. Despite their\nlarge diameter of 2 cm, the flexible materials are of high optical quality and\nyield mirror-like reflectivity of about 90% for neutrons of 4.1 nm wavelength.",
        "positive": "Quantum critical Bose gas in the two-dimensional limit in the honeycomb\n  antiferromagnet YbCl$_3$ under magnetic fields: BEC is a quantum phenomenon, where a macroscopic number of bosons occupy the\nlowest energy state and acquire coherence at low temperatures. It is realized\nnot only in $^4$He and dilute atomic gases, but also in quantum magnets, where\nhardcore bosons, introduced by the Matsubara-Matsuda transformation of spins,\ncondense. In 3D antiferromagnets, an XY-type long-range ordering (LRO) occurs\nnear a magnetic-field-induced transition to a fully polarized state (FP) and\nhas been successfully described as a BEC in the last few decades. An attractive\nextension of the BEC in 3D magnets is to make their 2D analogue. For a strictly\n2D system, BEC cannot take place due to the presence of a finite density of\nstates at zero energy, and a Berezinskii-Kosterlitz-Thouless (BKT) transition\nmay instead emerge. In a realistic quasi-2D magnet consisting of stacked 2D\nmagnets, a small but finite interlayer coupling stabilizes marginal LRO and\nBEC, but such that 2D physics, including BKT fluctuations, is still expected to\ndominate. A few systems were reported to show such 2D-limit BEC, but at very\nhigh magnetic fields that are difficult to access. The honeycomb $S$ = 1/2\nHeisenberg antiferromagnet YbCl$_3$ with an intra-layer coupling $J\\sim$ 5 K\nexhibits a transition to a FP state at a low in-plane magnetic field of $H_{\\rm\ns}$ = 5.93 T. Here, we demonstrate that the LRO right below $H_{\\rm s}$ is a\nBEC in the 2D-limit stabilized by an extremely small interlayer coupling\n$J_{\\perp}$ of 10$^{-5}J$. At the quantum critical point Hs, we capture\n2D-limit quantum fluctuations as the formation of a highly mobile, interacting\n2D Bose gas in the dilute limit. A much-reduced effective boson-boson repulsion\nUeff as compared with that of a prototypical 3D system indicates the presence\nof a logarithmic renormalization of interaction unique to 2D."
    },
    {
        "anchor": "The magnetic behavior of Li2MO3 (M=Mn, Ru and Ir) and Li2(Mn1-xRux)O3: The present study summerizes magnetic and Mossbauer measurements on ceramic\nLi2MO3 M= Mn, Ru and Ir and the mixed Li2(Mn1-xRux)O3 materials, which show\nmany of the features reflecting to antiferromagnetic ordering or to existence\nof paramagnetic states. Li2IrO3 and Li2RuO3 are paramagnetic down to 5 K.\nLi2(Mn1-xRux)O3 compounds are antiferromagnetically ordered at TN = 48 K for\nx=0. TN decreases as the Ru content increases and, for x=0.8, TN =34 K.",
        "positive": "Electrochemical Deposition of ZnO Hierarchical Nanostructures from\n  Hydrogel Coated Electrodes: The electrochemical deposition of ZnO hierarchical nanostructures directly\nfrom PHEMA hydrogel coated electrodes has been successfully demonstrated. A\nvariety of hierarchical ZnO nanostructures, including porous nanoflakes,\nnanosheets and nanopillar arrays were fabricated directly from the PHEMA\nhydrogel coated electrodes. Hybrid ZnO-hydrogel composite films were formed\nwith low zinc concentration and short electrodeposition time. A dual-layer\nstructure consisting of a ZnO/polymer and pure ZnO layer was obtained with zinc\nconcentration above 0.01 M. SEM observations and XPS depth profiling were used\nto investigate ZnO nanostructure formation in the early electrodeposition\nprocess. A growth mechanism to understand the formation of ZnO/hydrogel hybrid\nhierarchical nanostructures was developed. The I-V characteristics of the\nZnO-hydrogel composite films in dark and under ultraviolet (UV) illumination\ndemonstrate potential applications in UV photodetection."
    },
    {
        "anchor": "Element-specific and high-bandwidth ferromagnetic resonance spectroscopy\n  with a coherent, extreme ultraviolet (EUV) source: We developed and applied a tabletop, ultrafast, high-harmonic generation\n(HHG) source to measure the element-specific ferromagnetic resonance (FMR) in\nultra-thin magnetic alloys and multilayers on an opaque Si substrate. We\ndemonstrate a continuous wave bandwidth of 62 GHz, with promise to extend to\n100 GHz or higher. This laboratory-scale instrument detects the FMR using\nultrafast, extreme ultraviolet (EUV) light, with photon energies spanning the\nM-edges of most relevant magnetic elements. An RF frequency comb generator is\nused to produce a microwave excitation that is intrinsically synchronized to\nthe EUV pulses with a timing jitter of 1.4 ps or better. We apply this system\nto measure the dynamics in a multilayer system as well as Ni-Fe and Co-Fe\nalloys. Since this instrument operates in reflection-mode, it is a milestone\ntoward measuring and imaging the dynamics of the magnetic state and spin\ntransport of active devices on arbitrary and opaque substrates. The higher\nbandwidth also enables measurements of materials with high magnetic anisotropy,\nas well as ferrimagnets, antiferromagnets, and short-wavelength (high\nwavevector) spinwaves in nanostructures or nanodevices. Furthermore, the\ncoherence and short wavelength of the EUV will enable extending these studies\nusing dynamic nanoscale lensless imaging techniques such as coherent\ndiffractive imaging, ptychography, and holography.",
        "positive": "Nanocrystalline Zr3Al Made through Amorphization by Repeated Cold\n  Rolling and Followed by Crystallization: The intermetallic compound Zr3Al is severely deformed by the method of\nrepeated cold rolling. By X-ray diffraction it is shown that this leads to\namorphization. TEM investigations reveal that a homogeneously distributed\ndebris of very small nanocrystals is present in the amorphous matrix that is\nnot resolved by X-ray diffraction. After heating to 773 K, the crystallization\nof the amorphous structure leads to a fully nanocrystalline structure of small\ngrains (10 - 20 nm in diameter) of the non-equilibrium Zr2Al phase. It is\nconcluded that the debris retained in the amorphous phase acts as nuclei. After\nheating to 973 K the grains grow to about 100 nm in diameter and the compound\nZr3Al starts to form, that is corresponding to the alloy composition."
    },
    {
        "anchor": "Neutron Diffraction Studies on Temperature Driven Crystallographic\n  Anisotropy in FeVO4 Multiferroic: Evidence of Strong Magnetostructural\n  Correlations: We used temperature-dependent neutron diffraction measurements on FeVO4 to\nunderstand the temperature driven anisotropy and observed that the maximum\nchange for a and b lattice parameters in conjunction with a large contraction\nin angle \\beta\\ as a function of temperature. The least changes are observed\nfor the c lattice parameter and in \\gamma\\ angle. From these structural\nparameters, it can be said that, FeVO4 exhibits large structural anisotropy\nwith lowering temperature. The large change in lattice parameters in magnetic\nphases i.e. below 22 K explains the strong magnetostructural coupling in FeVO4.",
        "positive": "Anomalous temperature dependence of the band-gap in Black Phosphorus: Black Phosphorus (BP) has gained renewed attention due to its singular\nanisotropic electronic and optical properties that might be exploited for a\nwide range of technological applications. In this respect, the thermal\nproperties are particularly important both to predict its room temperature\noperation and to determine its thermoelectric potential. From this point of\nview, one of the most spectacular and poorly understood phenomena is, indeed,\nthe BP temperature-induced band-gap opening: when temperature is increased the\nfundamental band-gap increases instead of decreasing. This anomalous thermal\ndependence has also been observed, recently, in its monolayer counterpart. In\nthis work, based on \\textit{ab-initio} calculations, we present an explanation\nfor this long known, and yet not fully explained, effect. We show that it\narises from a combination of harmonic and lattice thermal expansion\ncontributions, which are, in fact, highly interwined. We clearly narrow down\nthe mechanisms that cause this gap opening by identifying the peculiar atomic\nvibrations that drive the anomaly. The final picture we give explains both the\nBP anomalous band-gap opening and the frequency increase with increasing volume\n(tension effect)."
    },
    {
        "anchor": "Performance of the r$^{2}$SCAN functional in transition metal oxides: We assess the accuracy and computational efficiency of the recently developed\nmeta-generalized gradient approximation (metaGGA) functional, the restored\nregularized strongly constrained and appropriately normed (r$^2$SCAN), in\ntransition metal oxide (TMO) systems and compare its performance against SCAN.\nSpecifically, we benchmark the r$^2$SCAN-calculated oxidation enthalpies,\nlattice parameters, on-site magnetic moments, and band gaps of binary\n3\\textit{d} TMOs against the SCAN-calculated and experimental values.\nAdditionally, we evaluate the optimal Hubbard \\emph{U} correction required for\neach transition metal (TM) to improve the accuracy of the r$^2$SCAN functional,\nbased on experimental oxidation enthalpies, and verify the transferability of\nthe \\emph{U} values by comparing against experimental properties on other\nTM-containing oxides. Notably, including the \\textit{U}-correction to r$^2$SCAN\nincreases the lattice parameters, on-site magnetic moments and band gaps of\nTMOs, apart from an improved description of the ground state electronic state\nin narrow band gap TMOs. The r$^2$SCAN and r$^2$SCAN+\\textit{U} calculated\noxidation enthalpies follow the qualitative trends of SCAN and SCAN+\\emph{U},\nwith r$^2$SCAN and r$^2$SCAN+\\textit{U} predicting marginally larger lattice\nparameters, smaller magnetic moments, and lower band gaps compared to SCAN and\nSCAN+\\textit{U}, respectively. We observe that the overall computational time\n(i.e., for all ionic+electronic steps) required for r$^2$SCAN(+\\textit{U}) to\nbe lower than SCAN(+\\textit{U}). Thus, the r$^2$SCAN(+\\textit{U}) framework can\noffer a reasonably accurate description of the ground state properties of TMOs\nwith better computational efficiency than SCAN(+\\textit{U}).",
        "positive": "Tuning the Structural, Electronic, and Magnetic Properties of Germanene\n  by the Adsorption of 3$d$ Transition Metal Atoms: The structural, electronic, and magnetic properties of 3$d$ transition metal\n(TM) atoms (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) adsorbed germanene are\naddressed using density functional theory. Based on the adsorption energy, TM\natoms prefer to occupy at the hollow site for all the cases. The obtained\nvalues of the total magnetic moment vary from 0.97 $\\mu_B$ to 4.95 $\\mu_B$ in\ncase of Sc to Mn-adsorption, respectively. A gap of 74 meV with a strongly\nenhanced splitting of 67 meV is obtained in case of Sc-adsorption, whereas\nmetallic states are obtained in case of Ti, Cr, Mn, Fe, and Co. Non-magnetic\nstates are realized for Ni, Cu, and Zn-adsorption. Moreover, semiconducting\nnature is obtained for non-magnetic cases with a gap of 26 to 28 meV.\nImportantly, it is found that V-adsorbed germanene can host the quantum\nanomalous Hall effect. The obtained results demonstrate that TM atoms and\nnearest neighbour Ge atoms are ferro-magnetically ordered in the cases of V,\nMn, Fe, Co, Ni, Cu, and Zn, while anti-ferromagnetic ordering is obtained for\nSc, Ti, and Cr. In addition, the effects of the coverage of all TM atoms on the\nelectronic structure and the ferro-magnetic and anti-ferro-magnetic coupling in\ncase of Mn are examined. The results could help to understand the effect of TM\natoms in a new class of two-dimensional materials beyond graphene and silicene."
    },
    {
        "anchor": "On the effect of Re addition on microstructural evolution of a\n  CoNi-based superalloy: In this study, the effect of rhenium (Re) addition on microstructural\nevolution of a new low-density Co-Ni-Al-Mo-Nb based superalloy is presented.\nAddition of Re significantly influences the {\\gamma}' precipitate morphology,\nthe {\\gamma}/{\\gamma}' lattice misfit and the {\\gamma}/{\\gamma}'\nmicrostructural stability during long term aging. An addition of 2 at.% Re to a\nCo-30Ni-10Al-5Mo-2Nb (all in at.%) alloy, aged at 900{\\deg}C for 50 hours,\nreduces the {\\gamma}/{\\gamma}' lattice misfit by {\\approx} 40% (from +0.32% to\n+0.19%, measured at room temperature) and hence alters the {\\gamma}' morphology\nfrom cuboidal to round-cornered cuboidal precipitates. The composition profiles\nacross the {\\gamma}/{\\gamma}' interface by atom probe tomography (APT) reveals\nRe partitions to the {\\gamma} phase (K_Re=0.34) and also results in the\npartitioning reversal of Mo to the {\\gamma} phase (K_Mo=0.90) from the\n{\\gamma}' precipitate. An inhomogeneous distribution of Gibbsian interfacial\nexcess for the solute Re ({\\Gamma}_Re, ranging from 0.8 to 9.6 atom.nm-2) has\nbeen observed at the {\\gamma}/{\\gamma}' interface. A coarsening study at\n900{\\deg}C (up to 1000 hours) suggests that the coarsening of {\\gamma}'\nprecipitates occurs solely by an evaporation--condensation (EC) mechanism. This\nis contrary to that observed in the Co-30Ni-10Al-5Mo-2Nb alloy as well as in\nsome of the Ni-Al based and high mass density Co-Al-W based superalloys, where\n{\\gamma}' precipitates coarsen by coagulation/coalescence mechanism with\nextensive alignment of {\\gamma}' along <100> directions as a sign of\nmicrostructural instability. The {\\gamma}' coarsening rate exponent (K_r) and\n{\\gamma}/{\\gamma}' interfacial energy are estimated to be 1.41 x 10-27 m3/s and\n8.4 mJ/m2, which are comparable and lower than Co-Al-W based superalloys.",
        "positive": "Theory of ferromagnetism driven by superexchange in dilute magnetic\n  semiconductors: Magnetic properties of Ga$_{1-x}$Mn$_x$N are studied theoretically by\nemploying a tight binding approach to determine exchange integrals $J_{ij}$\ncharacterizing the coupling between Mn spin pairs located at distances $R_{ij}$\nup to the 16th cation coordination sphere in zinc-blende GaN. It is shown that\nfor a set of experimentally determined input parameters there are no itinerant\ncarriers and the coupling between localized Mn$^{3+}$ spins in GaN proceeds via\nsuperexchange that is ferromagnetic for all explored $R_{ij}$ values. Extensive\nMonte Carlo simulations serve to evaluate the magnitudes of Curie temperature\n$T_\\mathrm{C}$ by the cumulant crossing method. The theoretical values of\n$T_\\mathrm{C}(x)$ are in quantitative agreement with the experimental data that\nare available for Ga$_{1-x}$Mn$_x$N with randomly distributed Mn$^{3+}$ ions\nwith the concentrations $0.01 \\leq x \\leq 0.1$."
    },
    {
        "anchor": "Atomic Origin of Ti Deficient Dislocation in SrTiO3 Bicrystal and Their\n  Electronic Structures: Dislocations in perovskite oxides have important impacts on their physical\nand chemical properties, which are determined by their unique atomic\nenvironments. In the present study, the structure of dislocations in a 10{\\deg}\nlow-angle grain boundary of SrTiO3 (STO) is characterized by spherical\naberration corrected scanning transmission electron microscopy (Cs-STEM) and\nspectroscopy. In contrast to previous studies, the deficiency instead of\nenrichment of titanium (Ti) is observed at the dislocation cores mainly due to\nthe Sr substitution and under occupancy of Ti. The presence of oxygen vacancies\nand partially reduced Ti are also detected at the Ti deficient dislocations\ncores. These findings indicate the atomic structure of dislocations can be very\ndifferent even they have the same Burges vectors. Controllable elemental\nsegregation in the dislocations and grain boundaries via bicrystal engineering\nshould be very useful for design of devices with novel functions.",
        "positive": "HDR: Interfaces in crystalline materials: Interfaces such as grain boundaries in polycrystalline as well as\nheterointerfaces in multiphase solids are ubiquitous in materials science and\nengineering. Far from being featureless dividing surfaces between neighboring\ncrystals, elucidating features of solid-solid interfaces is challenging and\nrequires theoretical and numerical strategies to describe the physical and\nmechanical characteristics of these internal interfaces. The first part of this\nmanuscript is concerned with interface-dominated microstructures emerging from\npolymorphic structural (diffusionless) phase transformations. Under high\nhydrostatic compression and shock-wave conditions, the pressure-driven phase\ntransitions and the formation of internal diffuse interfaces in iron are\ncaptured by a thermodynamically consistent framework for combining nonlinear\nelastoplasticity and multivariant phase-field approach at large strains. The\ncalculations investigate the crucial role played by the plastic deformation in\nthe morphological and microstructure evolution processes under high hydrostatic\ncompression and shock-wave conditions. The second section is intended to\ndescribe such imperfect interfaces at a finer scale, for which the semicoherent\ninterfaces are described by misfit dislocation networks that produce a\nlattice-invariant deformation which disrupts the uniformity of the lattice\ncorrespondence across the interfaces and thereby reduces coherency. For the\npast ten years, the constant effort has been devoted to combining the closely\nrelated Frank-Bilby and O-lattice techniques with the Stroh sextic formalism\nfor the anisotropic elasticity theory of interfacial dislocation patterns. The\nstructures and energetics are quantified and used for rapid computational\ndesign of interfaces with tailored misfit dislocation patterns, including the\ninterface sink strength for radiation-induced point defects and semicoherent\ninterfaces."
    },
    {
        "anchor": "A study of SnS thin films and its suitability for photovoltaic\n  application based on the existence of persistent photocurrent: Tin Sulphide is a layered compound which retains its structure when deposited\nas thin films by thermal evaporation. The films were found to have oriented\ngrowth with the direction of orientation changing with film thickness. The\nfilm's morphology was found to change with orientation. The poor conductivity\nof the thicker samples made it difficult to make photocunductivity\ncharacterisation. However, unlike reported the thinner samples showed\nphoto-sensitivity to be independent of film thickness and grain size with a\nhigh persistent photocurrent. With their absorption, photosensitivty, optimum\nband-gap and traps within the band-gap giving the charge carriers a longer\nlife-time, thin samples of tin sulphide gives adequate scope designing\nefficient photovoltaics. The refractive index was modeled using Sellmeir's\nmodel, while most of the previous studies talk of Wemple-DiDomenico single\noscillator model or Cauchy's dispersion relation. The Sellmeir's fitting\nparameters are reported which can be of use in ellipsometric studies.",
        "positive": "Magnetodielectric effects at quantum critical fields in\n  cobalt-containing garnets: Here we present a comparative study of the magnetic and crystal chemical\nproperties of two Co2+ containing garnets, NaCa2Co2V3O12 and CaY2Co2Ge3O12.\nBoth phases exhibit the onset of antiferromagnetic order at 8K and 6K\nrespectively, as well as field-induced transitions in their magnetization at 1T\nand around 11 T. We find these field-dependent transitions correspond to\nquantum critical points that result in the suppression of antiferromagnetic\norder and that these transitions can be clearly seen using magnetocapacitance\nmeasurements. Finally, we perform detailed crystal chemistry analyses and\ncomplimentary density functional theory calculations to show that changes in\nthe local environment of the Co-ions are responsible for differences in the two\nmagnetic structures and their respective properties."
    },
    {
        "anchor": "Scoping of material response under DEMO neutron irradiation: comparison\n  with fission and influence of nuclear library selection: Predictions of material activation inventories will be a key input to\nvirtually all aspects of the operation, safety and environmental assessment of\nfuture fusion nuclear plants. Additionally, the neutron-induced transmutation\n(change) of material composition (inventory) with time, and the creation and\nevolution of configurational damage from atomic displacements, require precise\nquantification because they can lead to significant changes in material\nproperties, and thus influence reactor-component lifetime. A comprehensive\nscoping study has been performed to quantify the activation, transmutation\n(depletion and build-up) and immediate damage response under neutron\nirradiation for all naturally occurring elements from hydrogen to bismuth. The\nresulting database provides a global picture of the response of a material,\ncovering the majority of nuclear technological space, but focussing\nspecifically on typical conditions expected for a demonstration fusion power\nplant (DEMO). Results from fusion are compared against typical fission\nconditions for selected fusion relevant materials, demonstrating that the\nlatter cannot be relied upon to give accurate scalable experimental predictions\nof material response in a future fusion reactor. Results from different nuclear\ndata libraries are also compared, highlighting the variations and deficiencies.",
        "positive": "Modeling Superionic Behavior of Plutonium Dioxide: The Bredig transition to the superionic phase indicated with the lambda-peak\nin Cp was highly expected for PuO2 as other actinide dioxides. However,\nleast-square fit and local smoothing techniques applied to the experimental\nenthalpy data of plutonium dioxide in 80's could not detect a lambda-peak in\nspecific heat that might be due to too scattered and insufficient experimental\ndata. Therefore, this issue has not been yet put beyond the doubts. In the\ncurrent article, a superionic model of PuO2 is developed with partially ionic\nmodel of a rigid ion potential. Thermophysical properties were calculated in\nconstant pressure-temperature ensemble using molecular dynamics simulation. The\nBredig transition with vicinity of a lambda-peak in specific heat was a\nsuccessfully observed for the model system at about 2100K. Moreover, the\nexperimental enthalpy change was well reproduced before and after the estimated\ntransition temperature."
    },
    {
        "anchor": "Microwave Heating of Water, Ice and Saline Solution: Molecular Dynamics\n  Study: In order to study the heating process of water by the microwaves of 2.5-20GHz\nfrequencies, we have performed molecular dynamics simulations by adopting a\nnon-polarized water model that have fixed point charges on rigid-body\nmolecules. All runs are started from the equilibrated states derived from the\nI$_{c}$ ice with given density and temperature. In the presence of microwaves,\nthe molecules of liquid water exhibit rotational motion whose average phase is\ndelayed from the microwave electric field. Microwave energy is transferred to\nthe kinetic and inter-molecular energies of water, where one third of the\nabsorbed microwave energy is stored as the latter energy. The water in ice\nphase is scarcely heated by microwaves because of the tight hydrogen-bonded\nnetwork of water molecules. Addition of small amount of salt to pure water\nsubstantially increases the heating rate because of the weakening by defects in\nthe water network due to sloshing large-size negative ions.",
        "positive": "Two-dimensional Janus van der Waals heterojunctions: a review of recent\n  research progresses: Two-dimensional Janus van der Waals (vdW) heterojunctions, referring to the\njunction containing at least one Janus material, are found to exhibit tuneable\nelectronic structures, wide light adsorption spectra, controllable contact\nresistance, and sufficient redox potential due to the intrinsic polarization\nand unique interlayer coupling. These novel structures and properties are\npromising for the potential applications in electronics and energy conversion\ndevices. To provide a comprehensive picture about the research progress and\nguide the following investigations, here we summarize their fundamental\nproperties of different types of two-dimensional Janus vdW heterostructures\nincluding electronic structure, interface contact and optical properties, and\ndiscuss the potential applications in electronics and energy conversion\ndevices. The further challenges and possible research directions of the novel\nheterojunctions are discussed at the end of this review."
    },
    {
        "anchor": "Dielectric Function of Diluted Magnetic Semiconductors in the Infrared\n  Regime: We present a study of the dielectric function of metallic (III,Mn)V diluted\nmagnetic semiconductors in the infrared regime. Our theoretical approach is\nbased on the kinetic exchange model for carrier induced (III,Mn)V\nferromagnetism. The dielectric function is calculated within the random phase\napproximation and, within this metallic regime, we treat disorder effects\nperturbatively and thermal effects within the mean field approximation. We also\ndiscuss the implications of this calculations on carrier concentration\nmeasurements from the optical f-sum rule and the analysis of plasmon-phonon\ncoupled modes in Raman spectra.",
        "positive": "T$_{d}$ to 1T$^{\\prime}$ structural phase transition in WTe$_{2}$ Weyl\n  semimetal: Elastic neutron scattering on a single crystal and powder X-ray diffraction\nmeasurements were carried out to investigate how the crystal structure evolves\nas a function of temperature in the Weyl semimetal WTe$_{2}$. A sharp\ntransition from the low-temperature orthorhombic phase (T$_{d}$) to the\nhigh-temperature monoclinic phase (1T$^{\\prime}$) was observed at ambient\npressure in the single crystal near $\\sim$565 K. Unlike in MoTe$_{2}$, the\nsolid-solid transition from T$_{d}$ to 1T$^{\\prime}$ occurs without the cell\ndoubling of the intermediate T$_{d}^{*}$ phase with AABB (or ABBA) layer\nstacking. In powders however, the thermal transition from the T$_{d}$ to the\n1T$^{\\prime}$ phase is broadened and a two phase coexistence was observed until\n700K, well above the structural transition."
    },
    {
        "anchor": "Learning local, quenched disorder in plasticity and other crackling\n  noise phenomena: When far from equilibrium, many-body systems display behavior that strongly\ndepends on the initial conditions. A characteristic such example is the\nphenomenon of plasticity of crystalline and amorphous materials that strongly\ndepends on the material history. In plasticity modeling, the history is\ncaptured by a quenched, local and disordered flow stress distribution. While it\nis this disorder that causes avalanches that are commonly observed during\nnanoscale plastic deformation, the functional form and scaling properties have\nremained elusive. In this paper, a generic formalism is developed for deriving\nlocal disorder distributions from field-response (e.g. stress/strain)\ntimeseries in models of crackling noise. We demonstrate the efficiency of the\nmethod in the hysteretic random-field Ising model and also, models of elastic\ninterface depinning that have been used to model crystalline and amorphous\nplasticity. We show that the capacity to resolve the quenched disorder\ndistribution improves with the temporal resolution and number of samples.",
        "positive": "Phononic Thin Plates with Embedded Acoustic Black Holes: We introduce a class of two-dimensional non-resonant single-phase phononic\nmaterials and investigate its peculiar dispersion characteristics. The material\nconsists of a thin plate-like structure with an embedded periodic lattice of\nAcoustic Black Holes. The use of these periodic tapers allows achieving\nremarkable dispersion properties such as Zero Group Velocity in the fundamental\nmodes, negative group refraction index, bi-refraction, and mode anisotropy. The\ndispersion properties are numerically investigated using a three-dimensional\nsupercell plane wave expansion method. The effect on the dispersion\ncharacteristics of key geometric parameters of the black hole, such as the\ntaper profile and the residual thickness, are also explored."
    },
    {
        "anchor": "Direct microscopic evidence of shear induced graphitization of\n  ultrananocrystalline diamond films: The origin of ultralow friction and high wear resistance in\nultrananocrystalline diamond (UNCD) films is still under active debate because\nof the perplexed tribochemistry at the sliding interface. Herein, we report a\ncomparative study on surface topography and nanoscale friction of tribofilms,\nin wear tracks of two sets of UNCD films having different structural\ncharacteristics. Despite both the films display ultralow coefficient of\nfriction, the UNCD films grown under Ar atmosphere (UNCDAr) exhibit a high wear\nresistance while the wear rate is higher for the films grown in N2 (UNCDN).\nFrictional force microscopic (FFM) investigations clearly reveal the\nmanifestation of shear induced graphitization on both the films. However, the\nwear track of UNCDAr films have a large network of a few layer graphene (FLG)\nstructures over the amorphous carbon tribofilms while only isolated clusters of\nFLG structures are present in the wear track of UNCDN films. Here, we\ndemonstrate the direct micro-/nanoscopic evidence for the formation of large\nnetwork of ~ 0.8 - 6 nm thick FLG structures, as a consequence of shear induced\ngraphitization and discuss their decisive role in ultralow friction and wear.",
        "positive": "Strain bursts in plastically deforming Molybdenum micro- and nanopillars: Plastic deformation of micron and sub-micron scale specimens is characterized\nby intermittent sequences of large strain bursts (dislocation avalanches) which\nare separated by regions of near-elastic loading. In the present investigation\nwe perform a statistical characterization of strain bursts observed in\nstress-controlled compressive deformation of monocrystalline Molybdenum\nmicropillars. We characterize the bursts in terms of the associated elongation\nincrements and peak deformation rates, and demonstrate that these quantities\nfollow power-law distributions that do not depend on specimen orientation or\nstress rate. We also investigate the statistics of stress increments in between\nthe bursts, which are found to be Weibull distributed and exhibit a\ncharacteristic size effect. We discuss our findings in view of observations of\ndeformation bursts in other materials, such as face-centered cubic and\nhexagonal metals."
    },
    {
        "anchor": "Numerical Simulation of Grain Boundary Grooving By Level Set Method: A numerical investigation of grain-boundary grooving by means of a Level Set\nmethod is carried out. An idealized polygranular interconnect which consists of\ngrains separated by parallel grain boundaries aligned normal to the average\norientation of the surface is considered. The surface diffusion is the only\nphysical mechanism assumed. The surface diffusion is driven by surface\ncurvature gradients, and a fixed surface slope and zero atomic flux are assumed\nat the groove root. The corresponding mathematical system is an initial\nboundary value problem for a two-dimensional Hamilton-Jacobi type equation. The\nresults obtained are in good agreement with both Mullins' analytical \"small\nslope\" solution of the linearized problem (W.W. Mullins, 1957) (for the case of\nan isolated grain boundary) and with solution for the periodic array of grain\nboundaries (S.A. Hackney, 1988).",
        "positive": "Electronic excitations stabilised by a degenerate electron gas in\n  semiconductors: Excitons in semiconductors and insulators consist of fermionic subsystems,\nelectrons and holes, whose attractive interaction facilitates bound\nquasiparticles with quasi-bosonic character due to even-numbered pair spins. In\nthe presence of a degenerate electron gas, such excitons dissociate due to free\ncarrier screening, leaving a spectrally broad and faint optical signature\nbehind. Contrary to this expected behaviour, we have discovered pronounced\nemission traces in bulk, germanium-doped GaN up to 100 K, mimicking excitonic\nbehaviour at high free electron concentrations from 3.4E19/cm3 to 8.9E19/cm3.\nConsequently, we show that a degenerate, three-dimensional electron gas\nstabilizes a novel class of quasiparticles, named collexons, by many-particle\neffects dominated by exchange of electrons with the Fermi gas. The observation\nof collexons and their stabilisation with rising doping concentration, is\nfacilitated by a superior crystal quality due to perfect substitution of the\nhost atom with the dopant."
    },
    {
        "anchor": "Absence of topological protection of the interface states in\n  $\\mathbb{Z}_2$ photonic crystals: Inspired from electronic systems, topological photonics aims to engineer new\noptical devices with robust properties. In many cases, the ideas from\ntopological phases protected by internal symmetries in fermionic systems are\nextended to those protected by crystalline symmetries. One such popular\nphotonic crystal model was proposed by Wu and Hu in 2015 for realizing a\nbosonic $\\mathbb{Z}_2$ topological crystalline insulator with robust\ntopological edge states, which led to intense theoretical and experimental\nstudies. However, rigorous relationship between the bulk topology and edge\nproperties for this model, which is central to evaluating its advantage over\ntraditional photonic designs, has never been established. In this work we\nrevisit the expanded and shrunken honeycomb lattice structures proposed by Wu\nand Hu by using topological quantum chemistry tools and show that they are\ntopologically trivial in the sense that symmetric, localized Wannier functions\ncan be constructed. We show that the $\\mathbb{Z}$ and $\\mathbb{Z}_2$ type\nclassification of the Wu-Hu model are equivalent to the $C_2T$ protected Euler\nclass and the second Stiefel-Whitney class respectively, with the latter\ncharacterizing the full valence bands of Wu-Hu model indicating only a higher\norder topological insulator (HOTI) phase. We show that the Wu-Hu interface\nstates can be gapped by a uniform topology preserving $C_6$ and $T$ symmetric\nperturbation, which demonstrates the trivial nature of the interface. Our\nresults reveals that topology is not a necessary condition for the reported\nhelical edge states in many photonics systems and opens new possibilities for\ninterface engineering that may not be constrained to require topological\ndesigns.",
        "positive": "Phonon-assisted processes in the ultraviolet transient optical response\n  of graphene: Many recent experiments investigated potential and attractive means of\nmodifying many-body interactions in two-dimensional materials through\ntime-resolved spectroscopy techniques. However, the role of ultrafast\nphonon-assisted processes in two-dimensional systems is rarely discussed in\ndepth. Here, we investigate the role of electron-phonon interaction in the\ntransient optical absorption of graphene by means of first-principles methods.\nIt is shown at equilibrium that the phonon-assisted transitions renormalize\nsignificantly the electronic structure. As a result, absorption peak around the\nVan Hove singularity broadens and redshifts by around 100\\,meV. In addition,\ntemperature increase and chemical doping are shown to notably enhance these\nphonon-assisted features. In the photoinduced transient response we obtain\nspectral changes in close agreement with the experiments, and we associate them\nto the strong renormalization of occupied and unoccupied $\\pi$ bands, which\npredominantly comes from the coupling with the zone-center $E_{2g}$ optical\nphonon. Our estimation of the Coulomb interaction effects shows that the\nphonon-assisted processes can have a dominant role even in the subpicosecond\nregime."
    },
    {
        "anchor": "Chemical Responsive Single Crystal Organic Magnet: Materials that change their magnetic properties in response to the external\nstimuli have long been of interest for their potential applicability in\nmagnetic storage device, spintronics and smart magnetic materials. Organic\nmaterials are suitable candidates for such materials due to their chemical\ndiversity, flexibility and designablity. However, most methods used for\nchanging magnetism are inefficient or destructive to the magnetic material.\nHence there is a need for innovation in this field. Here we report\nhigh-performance magnetic control of a gas-responsive single-molecule magnet\n(SMM). The results exhibit that the magnetic properties of the SMM can be\nsignificantly changed according to the gas environment it is in and some of the\nmagnetic states can be reversibly transformed or coexistent in the SMM through\nartificial control. More importantly, the monocrystalline structure of the SMM\nremains unchanged during the transformation process except for slight change of\nthe lattice constant. Thus, this work opens up new insights into the\nstimuli-responsive magnetic materials which have great prospects for\napplication in artificial design magnetic network and also highlight their\npotential as smart materials.",
        "positive": "Stacking-dependent topological magnons in bilayer CrI$_3$: Motivated by the potential of atomically-thin magnets towards tunable\nhigh-frequency magnonics, we detail the spin-wave dispersion of bilayer\nCrI$_3$. We demonstrate that the magnonic behavior of the bilayer strongly\ndepends on its stacking configuration and the interlayer magnetic ordering,\nwhere a topological bandgap opens in the dispersion caused by the\nDzyaloshinskii-Moriya and Kitaev interactions, classifying bilayer CrI$_3$ as a\ntopological magnon insulator. We further reveal that both size and topology of\nthe bandgap in a CrI$_3$ bilayer with an antiferromagnetic interlayer ordering\nare tunable by an external magnetic field."
    },
    {
        "anchor": "Quasiparticle electronic band structure of the alkali metal\n  chalcogenides: The electronic energy band spectra of the alkali metal chalcogenides M$_2$A\n(M: Li, Na, K, Rb; A: O, S, Se, Te) have been evaluated within the projector\naugmented waves (PAW) approach by means of the ABINIT code. The Kohn-Sham\nsingle-particle states have been found in the GGA (the generalized gradient\napproximation) framework. Further, on the basis of these results the\nquasiparticle energies of electrons as well as the dielectric constants were\nobtained in the GW approximation. The calculations based on the Green's\nfunction have been originally done for all the considered M$_2$A crystals,\nexcept Li$_2$O.",
        "positive": "First principles calculation of structural and magnetic properties for\n  Fe monolayers and bilayers on W(110): Structure optimizations were performed for 1 and 2 monolayers (ML) of Fe on a\n5 ML W(110) substrate employing the all-electron full-potential linearized\naugmented plane-wave (FP-LAPW) method. The magnetic moments were also obtained\nfor the converged and optimized structures. We find significant contractions\n($\\sim$ 10 %) for both the Fe-W and the neighboring Fe-Fe interlayer spacings\ncompared to the corresponding bulk W-W and Fe-Fe interlayer spacings. Compared\nto the Fe bcc bulk moment of 2.2 $\\mu_B$, the magnetic moment for the surface\nlayer of Fe is enhanced (i) by 15% to 2.54 $\\mu_B$ for 1 ML Fe/5 ML W(110), and\n(ii) by 29% to 2.84 $\\mu_B$ for 2 ML Fe/5 ML W(110). The inner Fe layer for 2\nML Fe/5 ML W(110) has a bulk-like moment of 2.3 $\\mu_B$. These results agree\nwell with previous experimental data."
    },
    {
        "anchor": "Features of the flexomagnetoelectric effect in an external magnetic\n  field: The paper investigates the influence of the magnetic field on the behavior of\n180-degree domain boundaries in a uniaxial ferromagnetic film with\ninhomogeneous magnetoelectric interaction. It is shown that, depending on the\nmagnitude and direction of the field, it is possible to strengthen or weaken\nthe flexomagnetoelectric effect in the sample under study. In addition, it was\nfound that in the reverse field, the effect of switching the nature of the\ninteraction of the electric field source with the domain wall from attraction\nto repulsion is possible.",
        "positive": "Magnetic Insulator-Induced Proximity Effects in Graphene: Spin Filtering\n  and Exchange Splitting Gaps: We report on first-principles calculations of spin-dependent properties in\ngraphene induced by its interaction with a nearby magnetic insulator (Europium\noxide, EuO). The magnetic proximity effect results in spin polarization of\ngraphene $\\pi$ orbitals by up to 24 %, together with large exchange splitting\nbandgap of about 36 meV. The position of the Dirac cone is further shown to\ndepend strongly on the graphene-EuO interlayer. These findings point towards\nthe possible engineering of spin gating by proximity effect at relatively high\ntemperature, which stands as a hallmark for future all-spin information\nprocessing technologies."
    },
    {
        "anchor": "Relativistic First-Principles Full Potential Calculations of Electronic\n  and Structural Properties of group IIIA-VA semiconductors based on Zeroth\n  Order Regular Approximation (ZORA) Hamiltonian: First-principles full potential calculations based on Zeroth Order Regular\nApproximation (ZORA) relativistic Hamiltonian and Kohn-Sham form of Density\nFunctional Theory (KS DFT) in local spin density approximation (LSDA) are\nreported for group IIIA-VA (InAs, GaAs, InP) semiconductors. The effects of\nrelativity are elucidated by performing fully relativistic, scalar\nrelativistic, and nonrelativistic calculations. Structural and electronic band\nstructure parameters are determined including split-off energies, band gaps,\nand deformation potentials. The nature of chemical bonding at the equilibrium\nand under hydrostatic strain is investigated using projected (PDOS) and overlap\npopulation weighted density of states (OPWDOS). ZORA results are compared with\nAugmented Plane Wave plus Local Orbitals method (APW+lo), and experiment.\nViability and robustness of the ZORA relativistic Hamiltonian for investigation\nof electronic and structural properties of semiconductors is established.",
        "positive": "Chiral Spin Bobbers in Exchange-Coupled Hard-Soft Magnetic Bilayers: The spin structure of exchange-coupled MnBi:Co-Fe bilayers is investigated by\nX-ray magnetic circular dichroism (XMCD), polarized neutron reflectometry\n(PNR), and micromagnetic simu-lations. The purpose of the present research is\ntwo-fold. First, the current search for new permanent-magnet materials includes\nhard-soft nanocomposites, and the analysis of coercivity mechanisms in these\nstructures is an important aspect of this quest. Second, topological\nmicro-magnetic structures such as skyrmions have recently become of intense\nfundamental and applied research, for example in the context of spin-based\nelectronics. We find that the magnetization reversal of the MnBi:Co-Fe bilayer\nstructure involves a curling-type twisting of the magnetization in the film\nplane. This curling in the exchange-coupled hard-soft magnetic bilayers is\nreminiscent of chiral spin structures known as bobbers and, in fact,\nestablishes a new type of skyrmionic spin structure."
    },
    {
        "anchor": "A one-dimensional model for the growth of CdTe quantum dots on Si\n  substrates: Recent experiments involving CdTe films grown on Si(111) substrates by hot\nwall epitaxy revealed features not previously observed [S. O. Ferreira\n\\textit{et al.}, J. Appl. Phys. \\textbf{93}, 1195 (2003)]. This system, which\nfollows the Volmer-Weber growth mode with nucleation of isolated 3D islands for\nless than one monolayer of evaporated material, was described by a peculiar\nbehavior of the quantum dot (QD) size distributions. In this work, we proposed\na kinetic deposition model to reproduce these new features. The model, which\nincludes thermally activated diffusion and evaporation of CdTe, qualitatively\nreproduced the experimental QD size distributions. Moreover, the model predicts\na transition from Stranski-Krastanow growth mode at lower temperatures to\nVolmer-Weber growth mode at higher ones characterized through the QD width\ndistributions.",
        "positive": "Determination of the quantized topological magneto-electric effect in\n  topological insulators from Rayleigh scattering: Topological insulators (TIs) exhibit many exotic properties. In particular, a\ntopological magneto-electric (TME) effect, quantized in units of the fine\nstructure constant, exists in TIs. In this Letter, we study theoretically the\nscattering properties of electromagnetic waves by TI circular cylinders\nparticularly in the Rayleigh scattering limit. Compared with ordinary\ndielectric cylinders, the scattering by TI cylinders shows many unusual\nfeatures due to the TME effect. Two proposals are suggested to determine the\nTME effect of TIs simply based on measuring the electric-field components of\nscattered waves in the far field at one or two scattering angles. Our results\ncould also offer a way to measure the fine structure constant."
    },
    {
        "anchor": "Transport and noise of hot electrons in GaAs using a semi-analytical\n  model of two-phonon polar optical phonon scattering: Recent ab-initio studies of electron transport in GaAs have reported that\nelectron-phonon (e-ph) interactions beyond the lowest order play a fundamental\nrole in charge transport and noise phenomena. Inclusion of the\nnext-leading-order process in which an electron scatters with two phonons was\nfound to yield good agreement for the high-field drift velocity, but the\ncharacteristic non-monotonic trend of the power spectral density of current\nfluctuations (PSD) with electric field was not predicted. The high\ncomputational cost of the ab-initio approach necessitated various\napproximations to the two-phonon scattering term, which were suggested as\npossible origins of the discrepancy. Here, we report a semi-analytical\ntransport model of two-phonon electron scattering via the Fr\\\"ohlich mechanism,\nallowing a number of the approximations in the ab-initio treatment to be lifted\nwhile retaining the accuracy to within a few percent. We compare the calculated\nand experimental transport and noise properties as well as scattering rates\nmeasured by photoluminescence experiments. We find quantitative agreement\nwithin 15% for the drift velocity and 25% for the $\\Gamma$ valley scattering\nrates, and agreement with the $\\Gamma-L$ intervalley scattering rates within a\nfactor of two. Considering these results and prior studies of current noise in\nGaAs, we conclude that the most probable origin of the non-monotonic PSD trend\nversus electric field is the formation of space charge domains rather than\nintervalley scattering as has been assumed.",
        "positive": "Dopant-mediated structural and magnetic properties of TbMnO3: Structural and magnetic properties of the doped terbium manganites (Tb,A)MnO3\n(A = Gd, Dy and Ho) have been investigated using first-principles calculations\nand further confirmed by subse- quent experimental studies. Both computational\nand experimental studies suggest that compared to the parent material, namely,\nTbMnO3 (with a magnetic moment of 9.7 /muB for Tb3+) Dy- and Ho- ion\nsubstituted TbMnO3 results in an increase in the magnetic moment (< 10.6/muB\nfor Dy3+ and Ho3+). The observed spiral-spin AFM order in TbMnO3 is stable with\nrespect to the dopant substitutions, which modify the Mn-O-Mn bond angles and\nlead to stronger the ferromagnetic component of the magnetic moment. Given the\nfact that magnetic ordering in TbMnO3 causes the ferroelectricity, this is an\nimportant step in the field of the magnetically driven ferroelectricity in the\nclass of magnetoelectric multiferroics, which traditionally have low magnetic\nmoments due to the predominantly antiferromagnetic order. In addition, the\npresent study reveals important insights on the phenomenological coupling\nmechanism in detail, which is essential in order to design new materials with\nenhanced magneto-electric effects at higher temperatures."
    },
    {
        "anchor": "Long-Time Magnetic Relaxation in Antiferromagnetic Topological Material\n  EuCd$_2$As$_2$: Magnetic topological materials have attracted much attention due to the\ncorrelation between topology and magnetism. Recent studies suggest that\nEuCd$_2$As$_2$ is an antiferromagnetic topological material. Here by carrying\nout thorough magnetic, electrical and thermodynamic property measurements, we\ndiscover a long time relaxation of the magnetic susceptibility in\nEuCd$_2$As$_2$. The (001) in-plane magnetic susceptibility at 5 K is found to\ncontinuously increase up to $\\sim$10% over the time of $\\sim$14 hours. The\nmagnetic relaxation is anisotropic and strongly depends on the temperature and\nthe applied magnetic field. These results will stimulate further theoretical\nand experimental studies to understand the origin of the relaxation process and\nits effect on the electronic structure and physical properties of the magnetic\ntopological materials.",
        "positive": "The commensurate phase of multiferroic HoMn2O5 studied by X-ray magnetic\n  scattering: The commensurate phase of multiferroic HoMn2O5 was studied by X-ray magnetic\nscattering, both off resonance and in resonant conditions at the Ho-L3 edge.\nBelow 40 K, magnetic ordering at the Ho sites is induced by the main Mn\nmagnetic order parameter, and its temperature dependence is well accounted for\nby a simple Curie-Weiss susceptibility model. A lattice distortion of\nperiodicity twice that of the magnetic order is also evidenced. Azimuthal scans\nconfirm the model of the magnetic structure recently refined from neutron\ndiffraction data for both Mn and Ho sites, indicating that the two sublattices\ninteract via magnetic superexchange."
    },
    {
        "anchor": "Defect-Dependent Corrugation in Graphene: Graphene's intrinsically corrugated and wrinkled topology fundamentally\ninfluences its electronic, mechanical, and chemical properties. Experimental\ntechniques allow the manipulation of pristine graphene and the controlled\nproduction of defects which allows to control the atomic out-of-plane\nfluctuations and, thus, tune graphene's properties. Here, we perform large\nscale machine learning-driven molecular dynamics simulations to understand the\nimpact of defects on the structure of graphene. We find that defects cause\nsignificantly higher corrugation leading to a strongly wrinkled surface. The\nmagnitude of this structural transformation strongly depends on the defect\nconcentration and specific type of defect. Analysing the atomic neighborhood of\nthe defects reveals that the extent of these morphological changes depends on\nthe preferred geometrical orientation and the interactions between defects.\nWhile our work highlights that defects can strongly affect graphene's\nmorphology, it also emphasises the differences between distinct types by\nlinking the global structure to the local environment of the defects.",
        "positive": "Orbit-transfer torque driven field-free switching of perpendicular\n  magnetization: The reversal of perpendicular magnetization (PM) by electric control is\ncrucial for high-density integration of low-power magnetic random-access memory\n(MRAM). Although the spin-transfer torque (STT) and spin-orbit torque (SOT)\ntechnologies have been used to switch the magnetization of a free layer with\nperpendicular magnetic anisotropy, the former has limited endurance because of\nthe high current density directly through the junction, while the latter\nrequires an external magnetic field or unconventional configuration to break\nthe symmetry. Here we propose and realize the orbit-transfer torque (OTT), that\nis, exerting torque on the magnetization using the orbital magnetic moments,\nand thus demonstrate a new strategy for current-driven PM reversal without\nexternal magnetic field. The perpendicular polarization of orbital magnetic\nmoments is generated by a direct current in a few-layer WTe2 due to the\nexistence of nonzero Berry curvature dipole, and the polarization direction can\nbe switched by changing the current polarity. Guided by this principle, we\nconstruct the WTe2/Fe3GeTe2 heterostructures, where the OTT driven field-free\ndeterministic switching of PM is achieved."
    },
    {
        "anchor": "Lifetimes of Stark-shifted image states: The inelastic lifetimes of electrons in image-potential states at Cu(100)\nthat are Stark-shifted by the electrostatic tip-sample interaction in the\nscanning tunneling microscope are calculated using the many-body GW\napproximation. The results demonstrate that in typical tunneling conditions the\nimage state lifetimes are significantly reduced from their field-free values.\nThe Stark-shift to higher energies increases the number of inelastic scattering\nchannels that are available for decay, with field-induced changes in the image\nstate wave function increasing the efficiency of the inelastic scattering\nthrough greater overlap with final state wave functions.",
        "positive": "Geometrical frustration in nonlinear mechanics of screw dislocation: The existence of stress singularities and reliance on linear approximations\npose significant challenges in comprehending the stress field generation\nmechanism around dislocations. This study employs differential geometry and\ncalculus of variations to mathematically model and numerically analyse screw\ndislocations. The kinematics of the dislocation are expressed by the\ndiffeomorphism of the Riemann--Cartan manifold, which includes both the\nRiemannian metric and affine connection. The modelling begins with a continuous\ndistribution of dislocation density, which is transformed into torsion $\\tau$\nthrough the Hodge duality. The plasticity functional is constructed by applying\nthe Helmholtz decomposition to bundle isomorphism, which is equivalent to the\nCartan first structure equation for the intermediate configuration\n$\\mathcal{B}$. The current configuration is derived by the elastic embedding of\n$\\mathcal{B}$ into the standard Euclidean space $\\mathbb{R}^3$. The numerical\nanalysis reveals the elastic stress fields effectively eliminate the\nsingularity along the dislocation line and exhibit excellent conformity with\nVolterra's theory beyond the dislocation core. Geometrical frustration is the\ndirect source of dislocation stress fields, as demonstrated through the\nmultiplicative decomposition of deformation gradients. By leveraging the\nmathematical properties of the Riemann--Cartan manifold, we demonstrate that\nthe Ricci curvature determines the symmetry of stress fields. These results\nsubstantiate a long-standing mathematical hypothesis: the duality between\nstress and curvature."
    },
    {
        "anchor": "First principles characterization of reversible martensitic\n  transformations: Reversible martensitic transformations (MTs) are the origin of many\nfascinating phenomena, including the famous shape memory effect. In this work,\nwe present a fully ab initio procedure to characterize MTs in alloys and to\nassess their reversibility. Specifically, we employ ab initio molecular\ndynamics data to parametrize a Landau expansion for the free energy of the MT.\nThis analytical expansion makes it possible to determine the stability of the\nhigh- and low-temperature phases, to obtain the Ehrenfest order of the MT, and\nto quantify its free energy barrier and latent heat. We apply our model to the\nhigh-temperature shape memory alloy Ti-Ta, for which we observe remarkably\nsmall values for the metastability region (the interval of temperatures in\nwhich the high-and low-temperature phases are metastable) and for the barrier:\nthese small values are necessary conditions for the reversibility of MTs and\ndistinguish shape memory alloys from other materials.",
        "positive": "Vibrational and magnetic properties of crystalline CuTe2O5: In the present work we have performed an ab initio calculation of vibrational\nproperties of CuTe2O5 by means of density functional theory method. One has\ncompared calculated values with known experimental data on Raman and infrared\nspectroscopy in order to verify the obtained results. Lattice contribution to\nthe heat capacity, obtained from the ab initio simulations was added to\nmagnetic contribution calculated from the simple spin hamiltonian model in\norder to obtain total heat capacity. Obtained result are in good agreement to\nthe experimental data. Thus, the DFT methods could complement the experimental\nand theoretical studying of low-dimensional magnetic systems such as CuTe2O5."
    },
    {
        "anchor": "DNP-NMR of surface hydrogen on silicon microparticles: Dynamic nuclear polarization (DNP) enhanced nuclear magnetic resonance (NMR)\noffers a promising route to studying local atomic environments at the surface\nof both crystalline and amorphous materials. We take advantage of unpaired\nelectrons due to defects close to the surface of the silicon microparticles to\nhyperpolarize adjacent $^{1}$H nuclei. At 3.3 T and 4.2 K, we observe the\npresence of two proton peaks, each with a linewidth on the order of 5 kHz. Echo\nexperiments indicate a homogeneous linewidth of $\\sim 150-300$ Hz for both\npeaks, indicative of a sparse distribution of protons in both environments. The\ndownfield peak at 10 ppm lies within the typical chemical shift range for\nproton NMR, and was found to be relatively stable over repeated measurements.\nThe upfield peak was found to vary in position between -19 and -37 ppm, well\noutside the range of typical proton NMR shifts, and indicative of a high-degree\nof chemical shielding. The upfield peak was also found to vary significantly in\nintensity across different experimental runs, suggesting a weakly-bound\nspecies. These results suggest that the hydrogen is located in two distinct\nmicroscopic environments on the surface of these Si particles.",
        "positive": "Spectroscopic data for the LiH molecule from pseudopotential quantum\n  Monte Carlo calculations: Quantum Monte Carlo and quantum chemistry techniques are used to investigate\npseudopotential models of the lithium hydride (LiH) molecule. Interatomic\npotentials are calculated and tested by comparing with the experimental\nspectroscopic constants and well depth. Two recently-developed pseudopotentials\nare tested, and the effects of introducing a Li core polarization potential are\ninvestigated. The calculations are sufficiently accurate to isolate the errors\nfrom the pseudopotentials and core polarization potential. Core-valence\ncorrelation and core relaxation are found to be important in determining the\ninteratomic potential."
    },
    {
        "anchor": "Applications of the generalized gradient approximation to ferroelectric\n  perovskites: The Perdew-Burke-Ernzerhof generalized gradient approximation to the density\nfunctional theory is tested with respect to sensitivity to the choice of the\nvalue of the parameter $\\kappa$, which is associated to the degree of\nlocalization of the exchange-correlation hole. A study of structural and\ndynamical properties of four selected ferroelectric perovskites is presented.\nThe originally proposed value of $\\kappa$=0.804 %(best suited for atoms and\nmolecules) works well for some solids, whereas for the ABO$_3$ perovskites it\nmust be decreased in order to predict equilibrium lattice parameters in good\nagreement with experiments. The effects on the structural instabilities and\nzone center phonon modes are examined. The need of varying $\\kappa$ from one\nsystem to another reflects the fact that the localization of the\nexchange-correlation hole is system dependent, and the sensitivity of the\nstructural properties to its actual value illustrates the necessity of finding\na universal function for $\\kappa$.",
        "positive": "The impact of physicochemical features of carbon electrodes on the\n  capacitive performance of supercapacitors: A machine learning approach: Hybrid electric vehicles and portable electronic systems use supercapacitors\nfor energy storage owing to their fast charging discharging rates, long life\ncycle, and low maintenance. Specific capacitance is regarded as one of the most\nimportant performance-related characteristics of a supercapacitor's electrode.\nIn the current study, Machine Learning (ML) algorithms were used to determine\nthe impact of various physicochemical properties of carbon-based materials on\nthe capacitive performance of electric double-layer capacitors. Published\nexperimental datasets from 147 references (4899 data entries) were extracted\nand then used to train and test the ML models, to determine the relative\nimportance of electrode material features on specific capacitance. These\nfeatures include current density, pore volume, pore size, presence of defects,\npotential window, specific surface area, oxygen, and nitrogen content of the\ncarbon-based electrode material. Additionally, categorical variables as the\ntesting method, electrolyte, and carbon structure of the electrodes are\nconsidered as well. Among five applied regression models, an extreme gradient\nboosting model was found to best correlate those features with the capacitive\nperformance, highlighting that the specific surface area, the presence of\nnitrogen doping, and the potential window are the most significant descriptors\nfor the specific capacitance. These findings are summarized in a modular and\nopen-source application for estimating the capacitance of supercapacitors\ngiven, as only inputs, the features of their carbon-based electrodes, the\nelectrolyte and testing method. In perspective, this work introduces a new wide\ndataset of carbon electrodes for supercapacitors extracted from the\nexperimental literature, also giving an instance of how electrochemical\ntechnology can benefit from ML models."
    },
    {
        "anchor": "Potential molecular semiconductor devices: cyclo-Cn (n = 10 and 14) with\n  higher stabilities and aromaticities than acknowledged cyclo-C18: The successful isolation of cyclo-C18 in the experiment means the\nground-breaking epoch of carbon rings. Herein, we studied the thermodynamic\nstabilities of cyclo-Cn (4 $\\leq$ n $\\leq$ 34) with density functional theory.\nWhen n = 4N + 2 (N is integer), cyclo-Cn (10 $\\leq$ n $\\leq$ 34) were\nthermodynamically stable. Especially, cyclo-C10 and cyclo-C14 were\nthermodynamically, kinetically, dynamically, and optically preferred to\ncyclo-C18, and were the candidates of zero-dimension carbon rings. The carbon\natoms were sp hybridization in cyclo-C10, cyclo-C14 and cyclo-C18. Cyclo-C14\nand cyclo-C18 had alternating abnormal single and triple bonds, but cyclo-C10\nhad equal bonds. Cyclo-C10, cyclo-C14, and cyclo-C18 with large aromaticities\nhad out-plane and in-plane pi systems, which were perpendicular to each other.\nThe number of pi electrons in out-plane and in-plane pi systems followed the\nHuckel rule. Simulated UV-vis-NIR spectra indicated the similar electronic\nstructures of cyclo-C14 and cyclo-C18.",
        "positive": "Bayesian Optimised Collection Strategies for Fatigue Strength Testing: A statistical framework is presented enabling optimal sampling and analysis\nof constant life fatigue data. Protocols using Bayesian maximum entropy\nsampling are built based on conventional staircase and stress step methods,\nreducing the requirement of prior knowledge for data collection. The Bayesian\nStaircase method shows improved parameter estimation efficiency, and the\nBayesian Stress Step method shows equal accuracy to the standard method at\nlarger step size allowing experimentalists to lessen concerns of loading\nhistory. Statistical methods for determining model suitability are shown,\nhighlighting the influence of protocol. Experimental validation is performed,\nshowing the applicability of the methods in laboratory testing."
    },
    {
        "anchor": "Giant Optomechanical Coupling in the Charge Density Wave State of\n  Tantalum Disulfide: We study the coupling of light and the structural order parameter in the\ncharge density wave (CDW) state of the layered transition-metal dichalcogenide,\nTantalum Disulfide ($1T-\\mathrm{TaS_2}$). Using time-dependent density\nfunctional theory calculations of the dielectric properties along the\ndistortions coordinates, we show that $1T-\\mathrm{TaS_2}$ displays very large\nchange in its dielectric function along the amplitude (Higgs) mode due to the\ncoupling of the periodic lattice distortion with an in-plane metal-insulator\ntransition, leading to optomechanical coupling coefficients two orders of\nmagnitude larger than the ones of diamond and ErFeO$_3$. In addition, we derive\nan effective model of the light-induced dynamics, which is in quantitative\nagreement with experimental observations in $1T-\\mathrm{TaS_2}$. We show that\nlight-induced dynamics of the structural order parameter in $1T-\\mathrm{TaS_2}$\ncan be deterministically controlled to engineer large third-order non-linear\noptical susceptibilities. Our findings suggest that CDW materials are promising\nactive materials for non-linear optics.",
        "positive": "Antiferromagnetic-ferromagnetic homostructures with Dirac magnons in van\n  der Waals magnet CrI$_3$: Van der Waals (vdW) Dirac magnon system CrI$_3$, a potential host of\ntopological edge magnons, orders ferromagnetically (FM) (T$_C=61$ K) in the\nbulk, but antiferromagnetic (AFM) order has been observed in nanometer thick\nflakes, attributed to monoclinic (M) type stacking. We report neutron\nscattering measurements on a powder sample where the usual transition to the\nrhombohedral (R) phase was inhibited for a majority of the structure. Elastic\nmeasurements (and the opening of a hysteresis in magnetization data on a\npressed pellet) showed that an AFM transition is clearly present below $\\sim$50\nK, coexisting with the R-type FM order. Inelastic measurements showed a\ndecrease in magnon energy compared to the R phase, consistent with a smaller\ninterlayer magnetic coupling in M-type stacking. A gap remains at the Dirac\npoint, suggesting that the same nontrivial magnon topology reported for the R\nphase may be present in the M phase as well."
    },
    {
        "anchor": "Discovery of a two-dimensional topological insulator in SiTe: Two-dimensional (2D) topological insulators (TIs), a new state of quantum\nmatter, are promising for achieving the low-power-consuming electronic devices\nowning to the remarkable robustness of their conducting edge states against\nbackscattering. Currently, the major challenge to further studies and possible\napplications is the lack of suitable materials, which should be with high\nfeasibility of fabrication and sizeable nontrivial gaps. Here, we demonstrate\nthrough first-principles calculations that SiTe 2D crystal is a promising 2D TI\nwith a sizeable nontrivial gap of 0.220 eV. This material is dynamically and\nthermally stable. Most importantly, it could be easily exfoliated from its\nthree-dimensional superlattice due to the weakly bonded layered structure.\nMoreover, strain engineering can effectively control its nontrivial gap and\neven induce a topological phase transition. Our results provide a realistic\ncandidate for experimental explorations and potential applications of 2D TIs.",
        "positive": "Molecular Doping of Multilayer MoS2 Field-effect Transistors: Reduction\n  in Sheet and Contact Resistances: For the first time, polyethyleneimine (PEI) doping on multilayer MoS2\nfield-effect transistors are investigated. A 2.6 times reduction in sheet\nresistance, and 1.2 times reduction in contact resistance have been achieved.\nThe enhanced electrical characteristics are also reflected in a 70% improvement\nin ON current, and 50% improvement in extrinsic field-effect mobility. The\nthreshold voltage also confirms a negative shift upon the molecular doping. All\nstudies demonstrate the feasibility of PEI molecular doping in MoS2\ntransistors, and its potential applications in layer-structured semiconducting\n2D crystals."
    },
    {
        "anchor": "Computational prediction of high thermoelectric performance in\n  As$_{2}$Se$_{3}$ by engineering out-of-equilibrium defects: We employed first-principles calculations to investigate the thermoelectric\ntransport properties of the compound As$_2$Se$_3$. Early experiments and\ncalculations have indicated that these properties are controlled by a kind of\nnative defect called antisites. Our calculations using the linearized Boltzmann\ntransport equation within the relaxation time approximation show good agreement\nwith the experiments for defect concentrations of the order of 10$^{19}$\ncm$^{-3}$. Based on our total energy calculations, we estimated the equilibrium\nconcentration of antisite defects to be about 10$^{14}$ cm$^{-3}$. These\nresults suggest that the large concentration of defects in the experiments is\ndue to kinetic and/or off-stoichiometry effects and in principle it could be\nlowered, yielding relaxation times similar to those found in other chalcogenide\ncompounds. In this case, for relaxation time higher than 10 fs, we obtained\nhigh thermoelectric figures of merit of 3 for the p-type material and 2 for the\nn-type one.",
        "positive": "Kinetics and the crystallographic structure of bismuth during\n  liquefaction and solidification on the insulating substrate: Here we study the kinetics of liquefaction and solidification of thin bismuth\nfilms grown on the insulating substrate by the pulsed laser deposited (PLD) and\nmolecular beam epitaxy (MBE) and investigated by in situ electron and X-ray\ndiffraction. By PLD, we can grow films similar to those obtained using MBE,\nstudied by ex-situ AFM, KPFM, XRR, and XRD. The liquefaction-solidification\ntransition is monitored in real-time by RHEED and synchrotron XRD, resulting in\na dewetting phenomenon and the formation of spherical droplets which size\ndepends on the initial film thickness. Studying this phase transition in more\ndetail, we find instantaneous liquefaction and solidification, resulting in\nformation of the nanodots oriented with a (110) crystallographic plane parallel\nto the substrate. Furthermore, we propose a two-step growth mechanism by\nanalyzing the recorded specular diffraction rods. Overall, we show that the PLD\nand MBE can be used as a method for the highly controlled growth of Bi\nnanostructures, including their crystallographic orientation on the substrate."
    },
    {
        "anchor": "Modulation frequency dependence of continuous-wave\n  optically/electrically detected magnetic resonance: Continuous wave optically and electrically detected magnetic resonance\nspectroscopy (cwODMR/cwEDMR) allow the investigation of paramagnetic states\ninvolved in spin-dependent transitions, like recombination and transport.\nAlthough experimentally similar to conventional electron spin resonance (ESR),\nthere exist limitations when applying models originally developed for ESR to\nobservables (luminescence and electric current) of cwODMR and cwEDMR. Here we\npresent closed-form solutions for the modulation frequency dependence of cwODMR\nand cwEDMR based on an intermediate pair recombination model and discuss\nambiguities which arise when attempting to distinguish the dominant\nspin-dependent processes underlying experimental data. These include: 1) a\nlarge number of quantitatively different models cannot be differentiated, 2)\nsigns of signals are determined not only by recombination, but also by other\nprocesses like dissociation, intersystem-crossing, pair generation, and even\nexperimental parameter such as, modulation frequency, microwave power, and\ntemperature, 3) radiative and non-radiative recombination cannot be\ndistinguished due to the observed signs of cwODMR and cwEDMR experiments.",
        "positive": "The two gap transitions in Ge$_{1-x}$Sn$_x$: effect of\n  non-substitutional complex defects: The existence of non-substitutional $\\beta$-Sn defects in Ge$_{1-x}$Sn$_{x}$\nwas confirmed by emission channeling experiments [Decoster et al., Phys. Rev. B\n81, 155204 (2010)], which established that although most Sn enters\nsubstitutionally ($\\alpha$-Sn) in the Ge lattice, a second significant fraction\ncorresponds to the Sn-vacancy defect complex in the split-vacancy configuration\n( $\\beta$-Sn ), in agreement with our previous theoretical study [Ventura et\nal., Phys. Rev. B 79, 155202 (2009)]. Here, we present our electronic structure\ncalculation for Ge$_{1-x}$Sn$_{x}$, including substitutional $\\alpha$-Sn as\nwell as non-substitutional $\\beta$-Sn defects. To include the presence of\nnon-substitutional complex defects in the electronic structure calculation for\nthis multi-orbital alloy problem, we extended the approach for the purely\nsubstitutional alloy by Jenkins and Dow [Jenkins and Dow, Phys. Rev. B 36, 7994\n(1987)]. We employed an effective substitutional two-site cluster equivalent to\nthe real non-substitutional $\\beta$-Sn defect, which was determined by a\nGreen's functions calculation. We then calculated the electronic structure of\nthe effective alloy purely in terms of substitutional defects, embedding the\neffective substitutional clusters in the lattice. Our results describe the two\ntransitions of the fundamental gap of Ge$_{1-x}$Sn$_{x}$ as a function of the\ntotal Sn-concentration: namely from an indirect to a direct gap, first, and the\nmetallization transition at higher $x$. They also highlight the role of\n$\\beta$-Sn in the reduction of the concentration range which corresponds to the\ndirect-gap phase of this alloy, of interest for optoelectronics applications."
    },
    {
        "anchor": "Dispersion corrections in graphenic systems: a simple and effective\n  model of binding: We combine high-level theoretical and \\emph{ab initio} understanding of\ngraphite to develop a simple, parametrised force-field model of interlayer\nbinding in graphite, including the difficult non-pairwise-additive\ncoupled-fluctuation dispersion interactions. The model is given as a simple\nadditive correction to standard density functional theory (DFT) calculations,\nof form $\\Delta U(D)=f(D)[U^{vdW}(D)-U^{DFT}(D)]$ where $D$ is the interlayer\ndistance. The functions are parametrised by matching contact properties, and\nlong-range dispersion to known values, and the model is found to accurately\nmatch high-level \\emph{ab initio} results for graphite across a wide range of\n$D$ values. We employ the correction on the difficult bigraphene binding and\ngraphite exfoliation problems, as well as lithium intercalated graphite\nLiC$_6$. We predict the binding energy of bigraphene to be 0.27 J/m^2, and the\nexfoliation energy of graphite to be 0.31 J/m^2, respectively slightly less and\nslightly more than the bulk layer binding energy 0.295 J/m^2/layer. Material\nproperties of LiC$_6$ are found to be essentially unchanged compared to the\nlocal density approximation. This is appropriate in view of the relative\nunimportance of dispersion interactions for LiC$_6$ layer binding.",
        "positive": "Stability, mechanisms and kinetics of emergence of Au surface\n  reconstructions using Bayesian force fields: Metal surfaces have long been known to reconstruct, significantly influencing\ntheir structural and catalytic properties. Many key mechanistic aspects of\nthese subtle transformations remain poorly understood due to limitations of\nprevious simulation approaches. Using active learning of Bayesian\nmachine-learned force fields trained from ab initio calculations, we enable\nlarge-scale molecular dynamics simulations to describe the thermodynamics and\ntime evolution of the low-index mesoscopic surface reconstructions of Au (e.g.,\nthe Au(111)-`Herringbone,' Au(110)-(1$\\times$2)-`Missing-Row,' and\nAu(100)-`Quasi-Hexagonal' reconstructions). This capability yields direct\natomistic understanding of the dynamic emergence of these surface states from\ntheir initial facets, providing previously inaccessible information such as\nnucleation kinetics and a complete mechanistic interpretation of reconstruction\nunder the effects of strain and local deviations from the original\nstoichiometry. We successfully reproduce previous experimental observations of\nreconstructions on pristine surfaces and provide quantitative predictions of\nthe emergence of spinodal decomposition and localized reconstruction in\nresponse to strain at non-ideal stoichiometries. A unified mechanistic\nexplanation is presented of the kinetic and thermodynamic factors driving\nsurface reconstruction. Furthermore, we study surface reconstructions on Au\nnanoparticles, where characteristic (111) and (100) reconstructions\nspontaneously appear on a variety of high-symmetry particle morphologies."
    },
    {
        "anchor": "Phenomenological theory of current driven exchange switching in\n  ferromagnetic nanojunctions: Phenomenological approach is developed in the theory of spin-valve type\nferromagnetic junctions to describe exchange switching by current flowing\nperpendicular to interfaces. Forward and backward current switching effects are\ndescribed and they may be principally different in nature. Mobile electron\nspins are considered as being free in all the contacting ferromagnetic layers.\nJoint action of the following two current effects is investigated: the\nnonequilibrium longitudinal spin-injection effective field and the transverse\nspin-transfer surface torque. Dispersion relation for fluctuations is derived\nand solved for a junction model having spatially localized spin transfer\ntorque: depth of the torque penetration into the free layer is assumed much\nsmaller than the total free layer thickness. Some critical value of the well\nknown Gilbert damping constant is established for the first time. Spin transfer\ntorque dominates in the instability threshold determination for small enough\ndamping constants, while the spin-injection effective field dominates for high\ndamping. Fine interplay between spin transfer torque and spin injection is\nnecessary to provide a hysteretic behavior of the resistance versus current\ndependence. The state diagram building up shows the possibility of\nnon-stationary (time dependent) nonlinear states arising due to instability\ndevelopment. Calculations lead to the instability rise time values of the order\nof 0.1 ns. Spin wave resonance frequency spectrum softening occurs under the\ncurrent growing to the instability threshold. Magnetization fluctuations above\nthe threshold rise oscillating with time for low damping, but rise\naperiodically and much more rapid for high damping.",
        "positive": "Spin-Transport in Defective Graphene Nanoribbons: Using first-principles calculations, the effect of magnetic point defects\n(vacancy and adatom) is investigated in zigzag graphene nanoribbons. The\nstructural, electronic, and spin-transport properties are studied. While\npristine ribbons display anti-parallel spin states at their edges, the defects\nare found to perturb this coupling. The introduction of a vacancy drastically\nreduces the energy difference between parallel and anti-parallel spin\norientations, though the latter is still favored. Moreover, the local magnetic\nmoment of the defect is screened by the edges so that the total magnetic moment\nis quite small. In contrast, when an adatom is introduced, the parallel spin\norientation is preferred and the local magnetic moment of the defect adds up to\nthe contributions of the edges. Furthermore, a spin-polarized transmission is\nobserved at the Fermi energy, suggesting the use of such a defective graphene\nnanoribbon as spin-valve device."
    },
    {
        "anchor": "Many-body electronic structure of LaScO$_3$ by real space quantum Monte\n  Carlo: We present real space quantum Monte Carlo (QMC) calculations of the scandate\nLaScO$_3$ that proved to be challenging for traditional electronic structure\napproaches due to strong correlation effects resulting in inaccurate band gaps\nfrom DFT and $GW$ methods when compared with existing experimental data.\nBesides calculating an accurate QMC band gap corrected for supercell size\nbiases and in agreement with numerous experiments, we also predict the cohesive\nenergy of the crystal using the standard fixed-node QMC without any empirical\nor non-variational parameters. We show that promotion (optical) gap and\nfundamental gap agree with each other illustrating a clear absence of\nsignificant excitonic effects in the ideal crystal. We obtained these results\nin perfect consistency in two independent tracks that employ different basis\nsets (plane wave vs. localized gaussians), different codes for generating\norbitals (\\textsc{Quantum Espresso} vs. \\textsc{Crystal}), different QMC codes\n(\\textsc{Qmcpack} vs. \\textsc{Qwalk}) and different high-accuracy\npseudopotentials (ccECPs vs. Troullier-Martins) presenting the maturity and\nconsistency of QMC methodology and tools for studies of strongly correlated\nproblems.",
        "positive": "Microwave-driven Topological Resonant Excitations of Coupled Skyrmions: We study nonlinear dynamics of coupled Skyrmions and present a method for\nmanipulating topological resonant excitations by a dual-frequency microwave\nfield. Thiele's equation is extended by introducing a new effective mass\nassociated with time derivative of topological density. Two coupled resonant\nmodes endowed with the new effective mass are found in the coupled Skyrmions.\nPolygon-like resonant excitations are observed and modulated when the two modes\nare activated simultaneously by microwave field with commensurate frequency\nratio. Quasiperiodic behavior of excitations are related to an incommensurate\nratio. Numerical solutions based on the extended Thiele's equation for Skyrmion\nunder a dual-frequency field agree well with the micromagnetic simulation\nresults and clarify the importance of frequency value, frequency ratio of an\nexternal field and the effective mass to the polygon-like dynamics of Skyrmion.\nWe also show the coupling between two Skyrmions can dominate their topological\nresonant excitations."
    },
    {
        "anchor": "An intermediate morphology in the patterning of the crystalline Ge(001)\n  surface induced by ion irradiation: We investigate the morphologies of the Ge(001) surface that are produced by\nbombardment with a normally incident, broad argon ion beam at sample\ntemperatures above the recrystallization temperature. Two previously-observed\nkinds of topographies are seen, i.e., patterns consisting of upright and\ninverted rectangular pyramids, as well as patterns composed of shallow,\nisotropic basins. In addition, we observe the formation of an unexpected third\ntype of pattern for intermediate values of the temperature, ion energy and ion\nflux. In this type of intermediate morphology, isolated peaks with rectangular\ncross sections stand above a landscape of shallow, rounded basins. We also\nextend past theoretical work to include a second order correction term that\ncomes from the curvature dependence of the sputter yield. For a range of\nparameter values, the resulting continuum model of the surface dynamics\nproduces patterns that are remarkably similar to the intermediate morphologies\nwe observe in our experiments. The formation of the isolated peaks is the\nresult of a term that is not ordinarily included in the equation of motion, a\nsecond order correction to the curvature dependence of the sputter yield.",
        "positive": "Modelling of dislocation generation and interaction during high-speed\n  deformation of metals: Recent experiments by Kiritani et al. have revealed a surprisingly high rate\nof vacancy production during high-speed deformation of thin foils of fcc\nmetals. Virtually no dislocations are seen after the deformation. This is\ninterpreted as evidence for a dislocation-free deformation mechanism at very\nhigh strain rates.\n  We have used molecular-dynamics simulations to investigate high-speed\ndeformation of copper crystals. Even though no pre-existing dislocation sources\nare present in the initial system, dislocations are quickly nucleated and a\nvery high dislocation density is reached during the deformation.\n  Due to the high density of dislocations, many inelastic interactions occur\nbetween dislocations, resulting in the generation of vacancies. After the\ndeformation, a very high density of vacancies is observed, in agreement with\nthe experimental observations. The processes responsible for the generation of\nvacancies are investigated. The main process is found to be incomplete\nannihilation of segments of edge dislocations on adjacent slip planes. The\ndislocations are also seen to be participating in complicated dislocation\nreactions, where sessile dislocation segments are constantly formed and\ndestroyed."
    },
    {
        "anchor": "Ge/Si(001) heterostructures with dense arrays of Ge quantum dots:\n  morphology, defects, photo-emf spectra and terahertz conductivity: Issues of Ge hut array formation and growth at low temperatures on the\nGe/Si(001) wetting layer are discussed on the basis of explorations performed\nby high resolution STM and in-situ RHEED. Data of HRTEM studies of multilayer\nGe/Si heterostructures are presented with the focus on low-temperature\nformation of perfect films. Heteroepitaxial Si p-i-n-diodes with multilayer\nstacks of Ge/Si(001) quantum dot dense arrays built in intrinsic domains have\nbeen investigated and found to exhibit the photo-emf in a wide spectral range\nfrom 0.8 to 5 mcm. An effect of wide-band irradiation by infrared light on the\nphoto-emf spectra has been observed. Photo-emf in different spectral ranges has\nbeen found to be differently affected by the wide-band irradiation. A\nsignificant increase in photo-emf is observed in the fundamental absorption\nrange under the wide-band irradiation. The observed phenomena are explained in\nterms of positive and neutral charge states of the quantum dot layers and the\nCoulomb potential of the quantum dot ensemble. By using a coherent source\nspectrometer, first measurements of terahertz dynamical conductivity\n(absorptivity) spectra of Ge/Si(001) heterostructures were performed at\nfrequencies 0.3-1.2 THz in the temperature interval from 300 to 5 K. The\neffective dynamical conductivity of the heterostructures with Ge quantum dots\nhas been discovered to be significantly higher than that of the structure with\nthe same amount of bulk germanium (not organized in an array of quantum dots).\nThe excess conductivity is not observed in the structures with the Ge coverage\nless than 8 \\AA. When a Ge/Si(001) sample is cooled down the conductivity\ndecreases. We discuss possible mechanisms that can be responsible for the\nobserved effects.",
        "positive": "Doping-induced superconductivity in the van der Waals superatomic\n  crystal Re$_6$Se$_8$Cl$_2$: Superatomic crystals are composed of discrete modular clusters that emulate\nthe role of atoms in traditional atomic solids$^{1-4}$. Owing to their unique\nhierarchical structures, these materials are promising candidates to host\nexotic phenomena, such as superconductivity and magnetism that can be revealed\nthrough doping$^{5-10}$. Low-dimensional superatomic crystals hold great\npromise as electronic components$^{11,12}$, enabling these properties to be\napplied to nanocircuits, but the impact of doping in such compounds remains\nunexplored. Here we report the electrical transport properties of\nRe$_6$Se$_8$Cl$_2$, a two-dimensional superatomic semiconductor$^{13,14}$.\nUsing an in situ current annealing technique, we find that this compound can be\nn-doped through Cl dissociation, drastically altering the transport behaviour\nfrom semiconducting to metallic and giving rise to superconductivity below\n$\\sim$ 9 K. This work is the first example of superconductivity in a van der\nWaals (vdW) superatomic crystal; more broadly, it establishes a new chemical\nstrategy to manipulate the electronic properties of vdW materials with labile\nligands."
    },
    {
        "anchor": "Step Free Energies at Faceted Solid-Liquid Interfaces from Equilibrium\n  Molecular Dynamics Simulations: In this work a method is proposed for computing step free energies for\nfaceted solid-liquid interfaces based on atomistic simulations. The method is\ndemonstrated in an application to (111) interfaces in elemental Si, modeled\nwith the classical Stillinger-Weber potential. The approach makes use of an\nadiabatic trapping procedure, and involves simulations of systems with\ncoexisting solid and liquid phases separated by faceted interfaces containing\nislands with different sizes, for which the corresponding equilibrium\ntemperatures are computed. We demonstrate that the calculated coexistence\ntemperature is strongly affected by the geometry of the interface. We find that\nisland radius is inversely proportional to superheating, allowing us to compute\nthe step free energy by fitting simulation data within the formalism of\nclassical nucleation theory. The approach outlined in this work paves the way\nto the calculation of step free energies relevant to the solidification of\nfaceted crystals from liquid mixtures, as encountered in nanowire growth by the\nvapor-liquid-solid mechanism and in alloy casting. The present work also shows\nthat at low undercoolings the Stillinger-Weber interatomic potential for Si\ntends to crystallize in the wurtzite, rather than the diamond-cubic structure.",
        "positive": "Thickness dependent effects of an intermediate molecular blocking layer\n  on the optoelectronic characteristics of organic bilayer photovoltaic cells: In this work we address the microscopic effects related to the implementation\nof a Bathophenanthroline (BPhen) exciton blocking layer (EBL) sandwiched\nbetween Ag cathode and molecular Diindenoperylene (DIP)/C60 bilayer of a\nphotovoltaic cell. Complementary studies of current density, external quantum\nefficiency, and photoluminescence quenching for EBL thicknesses up to 50 nm\nindicate that Ag atoms are able to penetrate through the whole 35 nm thick C60\nfilm into the crystalline DIP layer underneath, thereby enhancing exciton\nquenching if no blocking layer is applied. In contrast, an optimal trade-off\nbetween exciton blocking, suppression of metal penetration and electron\ntransport is achieved for a 5 nm thick BPhen layer yielding an improvement of\npower conversion efficiency by more than a factor of 2."
    },
    {
        "anchor": "Plethora of tunable Weyl fermions in kagome magnet Fe3Sn2 thin films: Interplay of magnetism and electronic band topology in unconventional magnets\nenables the creation and fine control of novel electronic phenomena. In this\nwork, we use scanning tunneling microscopy and spectroscopy to study thin films\nof a prototypical kagome magnet Fe3Sn2. Our experiments reveal an unusually\nlarge number of densely-spaced spectroscopic features straddling the Fermi\nlevel. These are consistent with signatures of low-energy Weyl fermions and\nassociated topological Fermi arc surface states predicted by theory. By\nmeasuring their response as a function of magnetic field, we discover a\npronounced evolution in energy tied to the magnetization direction. Electron\nscattering and interference imaging further demonstrates the tunable nature of\na subset of related electronic states. Our experiments provide the first\nvisualization of how in-situ spin reorientation drives changes in the\nelectronic density of states of the Weyl fermion band structure. Combined with\nprevious reports of massive Dirac fermions, flat bands and electronic\nnematicity, our work establishes Fe3Sn2 as a unique platform that harbors an\nextraordinarily wide array of topological and correlated electron phenomena.",
        "positive": "Strain induced phase transition from antiferromagnet to altermagnet: The newly discovered altermagnets are unconventional collinear compensated\nmagnetic systems, exhibiting even (d, g, or i-wave) spin-polarization order in\nthe band structure, setting them apart from conventional collinear ferromagnets\nand antiferromagnets. Altermagnets offer advantages of spin polarized current\nakin to ferromagnets, and THz functionalities similar to antifferomagnets,\nwhile introducing new novel effects like spin-splitter currents. A key\nchallenge for future applications and functionalization of altermagnets, is to\ndemonstrate controlled transitioning to the altermagnetic phase from other\nconventional phases in a single material. Here we prove a viable path towards\novercoming this challenge through a strain-induced transition from an\nantiferromagnetic to an altermagnetic phase in ReO$_2$. Combining spin group\nsymmetry analysis and \\textit{ab-initio} calculations, we demonstrate that\nunder compressive strain ReO$_2$ undergoes such transition, lifting the\nKramer's degeneracy of the band structure of the antiferromagnetic phase in the\nnon-relativistic regime. In addition, we show that this magnetic transition is\naccompanied by a metal insulator transition, and calculate the distinct spin\npolarized spectral functions of the two phases, which can be detected in angle\nresolved photo-emission spectroscopy experiments."
    },
    {
        "anchor": "Fast detection of water nanopockets underneath wet-transferred graphene: We report an investigation of the graphene/substrate interface morphology in\nlarge-area polycrystalline graphene grown by chemical-vapour deposition and\nwet-transferred onto Si wafers. We combined spectroscopic ellipsometry, X-ray\nphotoelectron spectroscopy and atomic-force microscopy in order to yield\nmorphological and chemical information about the system. The data showed that\nwet-transferred samples may randomly exhibit nanosized relief patterns\nindicative of small water nanopockets trapped between graphene and the\nunderlying substrate. These pockets affect the adhesion of graphene to the\nsubstrate, but can be efficiently removed upon a mild annealing in high vacuum.\nWe show that ellipsometry is capable of successfully and reliably detecting,\nvia multilayer dielectric modelling, both the presence of such a spurious\nintercalation layer and its removal. The fast, broadly applicable and\nnon-invasive character of this technique can therefore promote its application\nfor quickly and reliably assessing the degree of adhesion of graphene\ntransferred onto target substrates, either for ex-post evaluation or in-line\nprocess monitoring.",
        "positive": "Nonconventional screening of Coulomb interaction in two-dimensional\n  semiconductors and metals: A comprehensive cRPA study of MX2 (M=Mo, W, Nb,\n  Ta; X=S, Se, Te): Experimental observations of large exciton binding energies and\nnon-hydrogenic Rydberg series in 2D semiconducting TMDs, along with deviations\nin plasmon dispersion in 2D metallic TMDs, suggest the presence of a\nnonconventional screening of the Coulomb interaction. The experimentally\nobserved Mott insulating state in the charge density wave (CDW) reconstructed\nlattice of TMDs containing 4d and 5d elements further confirms the presence of\nstrong Coulomb interactions in these systems. In this study, we use\nfirst-principles electronic structure calculations and constrained random-phase\napproximation to calculate the Coulomb interaction parameters (partially\nscreened U and fully screened W) between localized $d$ electrons in 2D TMDs. We\nspecifically explore materials represented by the formula MX2 (M=Nb, Ta, Mo, W,\nand X=S, Se, Te) and consider three different phases (1H, 1T, and 1T'). Our\nresults show that the short-range interactions are strongly screened in all\nthree phases, whereas the long-range interactions remain significant even in\nmetallic systems. This nonconventional screening provides a compelling\nexplanation for the deviations observed in the usual hydrogenic Rydberg series\nand conventional plasmon dispersion in 2D semiconducting and metallic TMDs,\nrespectively. Our calculations yield on-site Coulomb interaction parameters U\nwithin the ranges of 0.8-2.5 eV, 0.8-1.9 eV, and 0.9-2.4 eV for the 1H, 1T, and\n1T' structures, respectively. Furthermore, our findings indicate a\nsubstantially high ratio of on-site effective Coulomb interaction to bandwidth\n(U_eff/W_b >> 1) in CDW TMDs, providing robust evidence for the experimentally\nobserved strongly correlated Mott phase."
    },
    {
        "anchor": "A high-mobility electronic system at an electrolyte-gated oxide surface: Electrolyte gating is a powerful technique for accumulating large carrier\ndensities in surface two-dimensional electron systems (2DES). Yet this approach\nsuffers from significant sources of disorder: electrochemical reactions can\ndamage or alter the surface of interest, and the ions of the electrolyte and\nvarious dissolved contaminants sit Angstroms from the 2DES. Accordingly,\nelectrolyte gating is well-suited to studies of superconductivity and other\nphenomena robust to disorder, but of limited use when reactions or disorder\nmust be avoided. Here we demonstrate that these limitations can be overcome by\nprotecting the sample with a chemically inert, atomically smooth sheet of\nhexagonal boron nitride (BN). We illustrate our technique with\nelectrolyte-gated strontium titanate, whose mobility improves more than tenfold\nwhen protected with BN. We find this improvement even for our thinnest BN, of\nmeasured thickness 6 A, with which we can accumulate electron densities nearing\n10^14 cm^-2. Our technique is portable to other materials, and should enable\nfuture studies where high carrier density modulation is required but\nelectrochemical reactions and surface disorder must be minimized.",
        "positive": "Femtosecond electron and spin dynamics probed by nonlinear optics: A theoretical calculation is performed for the ultrafast spin dynamics in\nnickel using an exact diagonalization method. The present theory mainly focuses\non a situation where the intrinsic charge and spin dynamics is probed by the\nnonlinear (magneto-)optical responses on the femtosecond time scale, i.e.\noptical second harmonic generation (SHG) and the nonlinear magneto-optical Kerr\neffect (NOLIMOKE). It is found that the ultrafast charge and spin dynamics are\nobservable on the time scale of 10 fs. The charge dynamics proceeds ahead of\nthe spin dynamics, which indicates the existence of a spin memory time. The\nfast decay results from the loss of coherence in the initial excited state.\nBoth the material specific and experimental parameters affect the dynamics. We\nfind that the increase of exchange interaction mainly accelerates the spin\ndynamics rather than the charge dynamics. A reduction of the hopping integrals,\nsuch as present at interfaces, slows down the spin dynamics significantly.\nBesides, it is found that a spectrally broad excitation yields the intrinsic\nspeed limit of the charge (SHG) and spin dynamics (NOLIMOKE) while a narrower\nwidth prolongs the dynamics. This magnetic interface dynamics then should\nbecome accessible to state of art time resolved nonlinear-optical experiments."
    },
    {
        "anchor": "Defect-Moderated Oxidative Etching of MoS2: We report a simple technique for the selective etching of bilayer and\nmonolayer MoS$_2$. In this work, chosen regions of MoS$_2$ were activated for\noxygen adsorption and reaction by the application of low doses of He$^+$ at 30\nkeV in a gas ion microscope. Raman spectroscopy, optical microscopy and\nscanning electron microscopy were used to characterize both the etched features\nand the remaining material. It has been found that by using a pre-treatment to\nintroduce defects, MoS$_2$ can be etched very efficiently and with high region\nspecificity by heating in air.",
        "positive": "Enhanced screening and spectral diversity in many-body elastic\n  scattering of excitons in two-dimensional hybrid metal-halide perovskites: In two-dimensional hybrid organic-inorganic metal-halide perovskites, the\nintrinsic optical lineshape reflects multiple excitons with distinct binding\nenergies, each dressed differently by the hybrid lattice. Given this\ncomplexity, a fundamentally far-reaching issue is how Coulomb-mediated\nmany-body interactions --- elastic scattering such as excitation-induced\ndephasing, inelastic exciton bimolecular scattering, and multi-exciton binding\n--- depend upon the specific exciton-lattice coupling. We report the intrinsic\nand density-dependent exciton pure dephasing rates and their dependence on\ntemperature by means of a coherent nonlinear spectroscopy. We find\nexceptionally strong screening effects on multi-exciton scattering relative to\nother two-dimensional single-atomic-layer semiconductors. Importantly, the\nexciton-density dependence of the dephasing rates is markedly different for\ndistinct excitons. These findings establish the consequences of particular\nlattice dressing on exciton many-body quantum dynamics, which critically define\nfundamental optical properties that underpin photonics and quantum\noptoelectronics in relevant exciton density regimes."
    },
    {
        "anchor": "Anisotropic Current-Controlled Magnetization Reversal in the\n  Ferromagnetic Semiconductor (Ga,Mn)As: Electrical current manipulation of magnetization switching through\nspin-orbital coupling in ferromagnetic semiconductor (Ga,Mn)As Hall bar devices\nhas been investigated. The efficiency of the current-controlled magnetization\nswitching is found to be sensitive to the orientation of the current with\nrespect to the crystalline axes. The dependence of the spin-orbit effective\nmagnetic field on the direction and magnitude of the current is determined from\nthe shifts in the magnetization switching angle. We find that the strain\ninduced effective magnetic field is about three times as large as the Rashba\ninduced magnetic field in our GaMnAs devices.",
        "positive": "Simulation of Laser Ablation in Aluminum: The Effectivity of Double\n  Pulses: Lasers are becoming a more and more important tool in cutting and shaping\nmaterials. Improving precision and effectivity is an ongoing demand in science\nand industry. One possibility are double pulses. Here we study laser ablation\nof aluminum by the two-temperature model. There the laser is modeled as a\nsource in a continuum heat conduction equation for the electrons, whose\ntemperature then is transferred to a molecular dynamics particle model by an\nelectron-phonon coupling term. The melting and ablation effectivity is\ninvestigated depending on the relative intensity and the time delay between two\nGaussian shaped laser pulses. It turns out that at least for aluminum the\noptimal pulse shapes are standard Gaussian pulses. For double pulses with delay\ntimes up to 200 ps we find a behavior as observed in experiment: the ablation\ndepth decreases beyond a delay of 10 ps even if one does not account for the\nweakening at the second pulse due to laser-plasma interaction."
    },
    {
        "anchor": "The electronic disorder landscape of mixed halide perovskites: Bandgap tunability of lead mixed-halide perovskites makes them promising\ncandidates for various applications in optoelectronics since they exhibit sharp\noptical absorption onsets despite the presence of disorder from halide\nalloying. Here we use localization landscape theory to reveal that the static\ndisorder due to compositional alloying for iodide:bromide perovskite\ncontributes at most 3 meV to the Urbach energy. Our modelling reveals that the\nreason for this small contribution is due to the small effective masses in\nperovskites, resulting in a natural length scale of around 20nm for the\n\"effective confining potential\" for electrons and holes, with short range\npotential fluctuations smoothed out. The increase in Urbach energy across the\ncompositional range agrees well with our optical absorption measurements. We\nmodel systems of sizes up to 80 nm in three dimensions, allowing us to explore\nhalide segregation, accurately reproducing the experimentally observed\nabsorption spectra and demonstrating the scope of our method to model\nelectronic structures on large length scales. Our results suggest that we\nshould look beyond static contribution and focus on the dynamic temperature\ndependent contribution to the Urbach energy.",
        "positive": "Structure and photo-induced volume changes of obliquely deposited\n  amorphous selenium: Atomic scale computer simulations on structures and photo induced volume\nchanges of flatly and obliquely deposited amorphous selenium films have been\ncarried out in order to understand how the properties of chalcogenide glasses\nare influenced by their preparation method. Obliquely deposited a-Se thin films\ncontain more coordination defects, larger voids than the flatly deposited ones.\nTo model the photo induced volume changes the electron excitation and hole\ncreation were treated independently within the framework of tight-binding\nformalism. Covalent and interchain bond breakings and formations were found.\nThe obliquely deposited samples containing voids showed a wide spectrum of\nphoto induced structural changes in microscopic and volume changes in\nmacroscopic levels."
    },
    {
        "anchor": "Undissociated screw dislocations in silicon: calculations of core\n  structure and energy: The stability of the perfect screw dislocation in silicon has been\ninvestigated using both classical potentials and first-principles calculations.\nAlthough a recent study by Koizumi et al . stated that the stable screw\ndislocation was located in both the 'shuffle' and the 'glide' sets of {111}\nplanes, it is shown that this result depends on the classical potential used,\nand that the most stable configuration belongs to the 'shuffle' set only, in\nthe centre of one hexagon. We also investigated the stability of an sp 2\nhybridization in the core of the dislocation, obtained for one metastable\nconfiguration in the 'glide' set. The core structures are characterized in\nseveral ways, with a description of the three-dimensional structure,\ndifferential displacement maps and derivatives of the disregistry.",
        "positive": "Magneto-optical anisotropies of 2D antiferromagnetic MPX$_3$ from first\n  principles: Here we systematically investigate the impact of the spin direction on the\nelectronic and optical properties of transition metal phosphorus\ntrichalcogenides (MPX$_3$, M=Mn, Ni, Fe; X=S, Se) exhibiting various\nantiferromagnetic arrangement within the 2D limit. Our analysis based on the\ndensity functional theory and versatile formalism of Bethe-Salpeter equation\nreveals larger exciton binding energies for MPS$_3$ (up to 1.1 eV in air) than\nMPSe$_3$(up to 0.8 eV in air), exceeding the values of transition metal\ndichalcogenides (TMDs). For the (Mn,Fe)PX$_3$ we determine the optically active\nband edge transitions, revealing that they are sensitive to in-plane magnetic\norder, irrespective of the type of chalcogen atom. We predict the anistropic\neffective masses and the type of linear polarization as an important\nfingerprints for sensing the type of magnetic AFM arrangements. Furthermore, we\nidentify the spin-orientation-dependent features such as the valley splitting,\nthe effective mass of holes, and the exciton binding energy. In particular, we\ndemonstrate that for MnPX$_3$ (X=S, Se) a pair of non equivalent K+ and K-\npoints exists yielding the valley splittings that strongly depend on the\ndirection of AFM aligned spins. Notably, for the out-of-plane direction of\nspins, two distinct peaks are expected to be visible below the absorption\nonset, whereas one peak should emerge for the in-plane configuration of spins.\nThese spin-dependent features provide an insight into spin flop transitions of\n2D materials. Finally, we propose a strategy how the spin valley polarization\ncan be realized in 2D AFM within honeycomb lattice."
    },
    {
        "anchor": "Rotation of hydrogen molecules during the dissociative adsorption on the\n  Mg(0001) surface: A first-principles study: Using first-principles calculations, we systematically study the potential\nenergy surfaces and dissociation processes of the hydrogen molecule on the\nMg(0001) surface. It is found that during the dissociative adsorption process\nwith the minimum energy barrier, the hydrogen molecule firstly orients\nperpendicular, and then rotates to be parallel to the surface. It is also found\nthat the orientation of the hydrogen molecule at the transition state is\nneither perpendicular nor parallel to the surface. Most importantly, we find\nthat the rotation causes a reduction of the calculated dissociation energy\nbarrier for the hydrogen molecule. The underlying electronic reasons for the\nrotation of the hydrogen molecule is also discussed in our paper.",
        "positive": "Thermal expansion of \u03b1-boron and some boron-rich pnictides: Thermal expansion of {\\alpha}-rhombohedral boron ({\\alpha}-B12) and two\nisostructural boron-rich pnictides (B12P2 and B12As2) has been studied between\n298 and 1280 K by high-temperature synchrotron X-ray diffraction. For all\nstudied phases no temperature-induced phase transitions have been observed. The\nobserved temperature dependencies of the lattice parameters and unit cell\nvolumes were found to be quasi-linear. Variation of the thermal expansion\ncoefficients in the group of boron-rich pnictides (B13N2 - B12P2 - B12As2) was\nanalyzed."
    },
    {
        "anchor": "Topological phonons in an inhomogeneously strained silicon-1: Evidence\n  of long-distance spin transport and unidirectional magnetoresistance of\n  phonons: Transverse acoustic waves in an inhomogeneous medium are analogues to\nelectromagnetic waves and will exhibit topological behavior due to the Berry\ngauge potential in the momentum space due to inhomogeneity. The inhomogeneous\n(or gradient) medium can be created using an applied strain gradient in a\nsemiconductor thin film (silicon) since the phonon frequency and dispersion\nwill be a function of the local strain along the strain gradient direction. As\na consequence, topological phonon mediated spin and heat transport can be\nengineered in the semiconductor thin films. Here, we present evidence of a\nlong-distance (100 um) spin transport in the freestanding Si thin film sample\nunder an applied strain gradient using transverse spin-Nernst effect\nmeasurement. The long-distance spin transport was attributed to the topological\nspin-Hall effect of phonons in an inhomogeneous medium. The inhomogeneous\nmedium was validated using unidirectional magnetoresistance of phonons where\nthe magnitude of the coefficient of the non-reciprocal response at room\ntemperature was as large as reported in the BiTeBr at low temperatures. The\ntopological phonons also manifested the topological Nernst effect. This work\nnot only enhances the current understanding of inhomogeneous systems but also\nlays the foundation of the topological and spin phononics.",
        "positive": "Reorientation Transition in Single-Domain (Ga,Mn)As: We demonstrate that the interplay of in-plane biaxial and uniaxial anisotropy\nfields in (Ga,Mn)As results in a magnetization reorientation transition and an\nanisotropic AC susceptibility which is fully consistent with a simple single\ndomain model. The uniaxial and biaxial anisotropy constants vary respectively\nas the square and fourth power of the spontaneous magnetization across the\nwhole temperature range up to T_C. The weakening of the anisotropy at the\ntransition may be of technological importance for applications involving\nthermally-assisted magnetization switching."
    },
    {
        "anchor": "Impedance spectroscopy and its application: Representation of dielectric properties by impedance spectroscopy (IS) is\nanalyzed carefully in this paper. It is found that IS is not a good tool to\ndescribe a uniform system because a pseudo relaxation peaks exists at low\nfrequency limit corresponding to direct current (DC) conductivity and two\nrelaxation peaks appears simultaneously corresponding to one relaxation process\nfor a high loss system with tand>1. However it is very convenient to describe a\nmultiple phase system with IS. When dielectric properties are shown by\nCole-Cole equation, only one Cole-Cole arc appears for one phase in IS,\ntherefore it is very easy to distinguish different phases from each other.\nEspecially, since pseudo relaxation exists at low frequency limit for each\nphase, the location of a certain relaxation process can be deduced by IS\nwithout any uncertainty. Furthermore, when dielectric properties are shown with\nspecific impedance spectroscopy (ISI), the information of microstructure can be\nobtained conveniently. Based on the theoretical results above, dielectric\nproperties of CaCu3Ti4O12 (CCTO) ceramics with giant dielectric constant (GDC)\nare investigated. Microstructure of CCTO is obtained by dielectric spectrometer\nand the origin of GDC is found to come from pseudo relaxation of grain.",
        "positive": "Theory of PbTiO3, BaTiO3, and SrTiO3 Surfaces: First-principles total-energy calculations are carried out for (001) surfaces\nof the cubic perovskite ATiO3 compounds PbTiO3, BaTiO3, and SrTiO3. Both\nAO-terminated and TiO2-terminated surfaces are considered, and fully-relaxed\natomic configurations are determined. In general, BaTiO3 and SrTiO3 are found\nto have a rather similar behavior, while PbTiO3 is different in many respects\nbecause of the partially covalent character of the Pb-O bonds. PbTiO3 and\nBaTiO3 are ferroelectrics, and the influence of the surface upon the\nferroelectric distortions is studied for the case of a tetragonal ferroelectric\ndistortion parallel to the surface. The surface relaxation energies are found\nto be substantial, i.e., many times larger than the bulk ferroelectric well\ndepth. Nevertheless, the influence of the surface upon the ferroelectric order\nparameter is modest, and is qualitatively as well as quantitatively different\nfor the two materials. Surface energies and electronic properties are also\ncomputed. It is found that for BaTiO3 and SrTiO3 surfaces, both AO-terminated\nand TiO2-terminated surfaces can be thermodynamically stable, whereas for\nPbTiO3 only the PbO surface termination is stable."
    },
    {
        "anchor": "Dislocation density distribution at slip band-grain boundary\n  intersections: We study the mechanisms of slip transfer at a grain boundary, in titanium,\nusing Differential Aperture X-ray Laue Micro-diffraction (DAXM). This 3D\ncharacterization tool enables measurement of the full (9-component) Nye lattice\ncurvature tensor and calculation of the density of geometrically necessary\ndislocations (GNDs). We observe dislocation pile-ups at a grain boundary, as\nthe neighbor grain prohibits easy passage for dislocation transmission. This\nincompatibility results in local micro-plasticity within the slipping grain,\nnear to where the slip planes intersect the grain boundary, and we observe\nbands of GNDs lying near the grain boundary. We observe that the distribution\nof GNDs can be significantly influenced by the formation of grain boundary\nledges that serve as secondary dislocation sources. This observation highlights\nthe non-continuum nature of polycrystal deformation and helps us understand the\nhigher order complexity of grain boundary characteristics.",
        "positive": "Unveiling the impact of temperature on magnon diffuse scattering\n  detection in the transmission electron microscope: Magnon diffuse scattering (MDS) signals could be studied with high spatial\nresolution in scanning transmission electron microscopy (STEM), thanks to\nrecent technological progress in electron energy loss spectroscopy. However,\ndetecting MDS signals in STEM is challenging due to their overlap with stronger\nthermal diffuse scattering (TDS) signals. In bcc Fe at 300 K, MDS signals\ngreater than or comparable to TDS signals occur under the central Bragg disk,\ninto a currently inaccesible energy-loss region. Therefore, to detect MDS in\nSTEM, it is necessary to find conditions in which TDS and MDS signals can be\nseparated. Temperature may be a key factor due to the distinct thermal\nsignatures of magnon and phonon signals. In this work, we present a study on\nthe effects of temperature on MDS and TDS in bcc Fe -- considering a detector\noutside the central Bragg disk and a fixed convergent electron probe -- using\nthe frozen phonon and frozen magnon multislice methods. Our study reveals that\nneglecting the effects of atomic vibrations causes the MDS signal to grow\napproximately linearly up to the Curie temperature of Fe, after which it\nexhibits less variation. The MDS signal displays an alternating behavior due to\ndynamical diffraction, instead of increasing monotonically as a function of\nthickness. Including the effects of atomic vibrations through a complex atomic\nelectrostatic potential causes the linear growth of the MDS signal to change to\na non-linear behavior that exhibits a predominant peak for a sample of\nthickness 16.072 nm at 1100 K. In contrast, the TDS signal grows more linearly\nthan the MDS signal but still exhibits appreciable dynamical diffraction\neffects. An analysis of the signal-to-noise ratio (SNR) shows that the MDS\nsignal can be a statistically significant contribution to the total scattering\nintensity under realizable measurement conditions and acquisition times."
    },
    {
        "anchor": "Magnetocaloric effect and improved relative cooling power in\n  (La0.7Sr0.3MnO3/SrRuO3) superlattices: Magnetic properties of a series of (La0.7Sr0.3MnO3/SrRuO3) superlattices,\nwhere the SrRuO3 layer thickness is varying, are examined. A room-temperature\nmagnetocaloric effect is obtained owing to the finite size effect which reduces\nthe TC of La0.7Sr0.3MnO3 layers. While the working temperature ranges are\nenlarged,, -DeltaSmax values remains similar to the values in polycrystalline\nLa0.7Sr0.3MnO3. Consequently, the relative cooling powers are significantly\nimproved, the microscopic mechanism of which is related to the effect of the\ninterfaces at La0.7Sr0.3MnO3/SrRuO3 and higher nanostructural disorder. This\nstudy indicates that artificial oxide superlattices/multilayers might provide\nan alternative pathway in searching for efficient room-temperature magnetic\nrefrigerators for (nano)microscale systems.",
        "positive": "Crystallographic effects on transgranular chloride-induced stress\n  corrosion crack propagation of arc welded austenitic stainless steel: The effect of crystallography on transgranular chloride-induced stress\ncorrosion cracking (TGCISCC) of arc welded 304L austenitic stainless steel is\nstudied on >300 grains along crack paths. Schmid and Taylor factor mismatches\nacross grain boundaries (GBs) reveal that cracks propagate either from a hard\nto soft grain, which can be explained merely by mechanical arguments, or soft\nto hard grain. In the latter case, finite element analysis reveals that TGCISCC\nwill arrest at GBs without sufficient mechanical stress, favorable\ncrystallographic orientations, or crack tip corrosion. GB type does not play a\nsignificant role in determining TGCISCC cracking behavior nor susceptibility.\nTGCISCC crack behaviors at GBs are discussed in the context of the competition\nbetween mechanical, crystallographic, and corrosion factors."
    },
    {
        "anchor": "Disentangling stress and curvature effects in layered 2D ferroelectric\n  CuInP2S6: Nanoscale ferroelectric 2D materials offer unique opportunity to investigate\ncurvature and strain effects on materials functionalities. Among these,\nCuInP2S6 (CIPS) has attracted tremendous research interest in recent years due\nto combination of room temperature ferroelectricity, scalability to a few\nlayers thickness, and unique ferrielectric properties due to coexistence of 2\npolar sublattices. Here, we explore the local curvature and strain effect on\nthe polarization in CIPS via piezoresponse force microscopy and spectroscopy.\nTo explain the observed behaviors and decouple the curvature and strain effects\nin 2D CIPS, we introduce finite element Landau-Ginzburg-Devonshire model. The\nresults show that bending induces ferrielectric domains in CIPS, and the\npolarization-voltage hysteresis loops differ in bending and non-bending\nregions. Our simulation indicates that the flexoelectric effect can affect\nlocal polarization hysteresis. These studies open a novel pathway for the\nfabrication of curvature-engineered nanoelectronic devices.",
        "positive": "In situ photoluminescence and Raman study of nanoscale morphological\n  changes in organic photovoltaics during solvent vapor annealing: Improvement of the photovoltaic efficiency (from 1.2% to 3%) via exposure of\norganic poly(3-hexylthiophene) (P3HT) + phenyl-C61-butyric acid methyl ester\n(PCBM) devices to solvent vapor at room temperature is reported. In situ\nphotoluminescence (PL) and Raman spectroscopies, in conjunction with optical\nabsorption data, have been used to provide insight into the nanoscale\nmorphological changes occurring during solvent vapor annealing. We found that\nin P3HT:PCBM, suppression of PL and the decrease in line-width of the 1442 cm-1\nP3HT Raman peak are accompanied by strong modifications in the optical\nabsorption spectra during solvent vapor annealing, in contrast to measurements\non P3HT only films. We attribute these observations to de-mixing of PCBM and\nsubsequent stacking of P3HT in coplanar conjugated segments, similar to what is\nobserved during thermal annealing."
    },
    {
        "anchor": "Dynamics of Shear-Transformation Zones in Amorphous Plasticity:\n  Formulation in Terms of an Effective Disorder Temperature: This investigation extends earlier studies of a shear-transformation-zone\n(STZ) theory of plastic deformation in amorphous solids. My main purpose here\nis to explore the possibility that the configurational degrees of freedom of\nsuch systems fall out of thermodynamic equilibrium with the heat bath during\npersistent mechanical deformation, and that the resulting state of\nconfigurational disorder may be characterized by an effective temperature. The\nfurther assumption that the population of STZ's equilibrates with the effective\ntemperature allows the theory to be compared directly with experimentally\nmeasured properties of metallic glasses, including their calorimetric behavior.\nThe coupling between the effective temperature and mechanical deformation\nsuggests an explanation of shear-banding instabilities.",
        "positive": "Crystal and electronic structure of a quasi-two-dimensional\n  semiconductor Mg$_3$Si$_2$Te$_6$: We report the synthesis and characterization of a Si-based ternary\nsemiconductor Mg$_3$Si$_2$Te$_6$, which exhibits a quasi-two-dimensional\nstructure, where the trigonal Mg$_2$Si$_2$Te$_6$ layers are separated by Mg\nions. Ultraviolet-visible absorption spectroscopy and density functional theory\ncalculations were performed to investigate the electronic structure. The\nexperimentally determined direct band gap is 1.39 eV, consistent with the value\nof the density function theory calculations. Our results reveal that\nMg$_3$Si$_2$Te$_6$ is a direct gap semiconductor with a relatively narrow gap,\nwhich is a potential candidate for infrared optoelectronic devices."
    },
    {
        "anchor": "The influence of beam focus during laser powder bed fusion of a high\n  reflectivity aluminium alloy -- AlSi$_{10}$Mg: LPBF of Al alloys is associated with numerous challenges when compared to\nother commonly used alloys due to their higher reflectivity and thermal\nconductivity. In this work, processing diagrams, temperature prediction models,\nXCT, and metallography are used for establishing criteria in process parameter\noptimization of high reflectivity Al alloys based on AlSi$_{10}$Mg response in\nusing 57 different process parameter combinations - 21 using a focused Gaussian\nlaser beam and 36 using divergent beams. For LPBF systems with focused beam\ndiameters <100 {\\mu}m, divergent beams obtained by defocusing to a position\nabove the LPBF build plate primarily lead to conduction mode melt pools, while\na focused beam leads to transition and keyhole mode melt pools. Conduction mode\nmelting helps in avoiding keyhole mode defects, resulting in parts with\ndensities >99.98%. Additionally, an analytical model-guided selection of laser\npower and velocity settings for a focused beam help in stabilizing melt pool\nand spatter dynamics in the transition melting mode thereby enabling a\npotential to obtain density values close to conduction mode densities\n(~99.98%). A dimensionless keyhole number (Ke) was derived in this work to\nidentify distinct regions of conduction (Ke of 0-12), transition (Ke of 12-20),\nand keyhole (Ke > 20) mode melting during LPBF of AlSi$_{10}$. A melt pool\naspect ratio (ratio of melt pool depth to width) of ~0.4 is observed to be the\nthreshold between conduction and transition/keyhole mode melt pools for\nAlSi$_{10}$, different from the conventionally assumed 0.5. Lastly, inferred\nlaser absorptivity values (from experimental melt pools) of transition/keyhole\nmode melt pools are observed to be >40% higher when compared to conduction mode\nmelt pools. This work demonstrates a dimensionless-process map method to obtain\nnear fully dense parts that can be generalized for LPBF of high reflectivity\nalloys.",
        "positive": "Interactive Human-Machine Learning Framework for Modelling of\n  Ferroelectric-Dielectric Composites: Data driven materials discovery and optimization requires databases that are\nerror free and experimentally verified. Performing material measurements are\ntime-consuming and often restricted by the fact that material sample\npreparations are non-trivial, labour-intensive and expensive. Numerical\nmodelling of materials has been studied over the years in order to address\nthese issues and nowadays it has been developed at multi-scale and\nmulti-physics levels. However, numerical models for nano-composites, especially\nfor ferroelectrics are limited due to multiple unknowns including oxygen\nvacancy densities, grain sizes and domain boundaries existing in the system. In\nthis work, we introduce a human-machine interactive learning framework by\ndeveloping a scalable semi-empirical model to accurately predict material\nproperties enabled by deep learning (DL). MgO-doped BST (BaxSr1-xTiO3) is\nselected as an example ferroelectric-dielectric composite for validation. The\nDL model transfer-learns the experimental features of materials from a\nmeasurement database which includes data for over 100 different ferroelectric\ncomposites collected by screening the published data and combining our own\nmeasurement data. The trained DL model is utilized in providing feedback to\nhuman researchers, who then refine computer model parameters accordingly, hence\ncompleting the interactive learning cycle. Finally, the developed DL model is\napplied to predict and optimise new ferroelectric-dielectric composites with\nthe highest figure of merit (FOM) value."
    },
    {
        "anchor": "First-Principles-Based Thermodynamic Description of Solid Copper Using\n  the Tight-Binding Approach: A tight-binding model is fit to first-principles calculations for copper that\ninclude structures distorted according to elastic constants and high-symmetry\nphonon modes. With the resulting model the first-principles-based phonon\ndispersion and the free energy are calculated in the quasi-harmonic\napproximation. The resulting thermal expansion, the temperature- and\nvolume-dependence of the elastic constants, the Debye temperature, and the\nGruneisen parameter are compared with available experimental data.",
        "positive": "Magnetic States and Electronic Properties of Manganese-Based\n  Intermetallic Compounds Mn$_2$YAl and Mn$_3$Z (Y = V, Cr, Fe, Co, Ni; Z = Al,\n  Ge, Sn, Si, Pt): We present a brief review of experimental and theoretical papers on studies\nof electron transport and magnetic properties in manganese-based compounds\nMn$_2$YZ and Mn$_3$Z (Y = V, Cr, Fe, Co, Ni, etc.; Z = Al, Ge, Sn, Si, Pt,\netc.). It has been shown that in the electronic subsystem of Mn$_2$YZ\ncompounds, the states of a half-metallic ferromagnet and a spin gapless\nsemiconductor can arise with the realization of various magnetic states, such\nas a ferromagnet, a compensated ferrimagnet, and a frustrated antiferromagnet.\nBinary compounds Mn$_3$Z have the properties of a half-metallic ferromagnet and\na topological semimetal with a large anomalous Hall effect, spin Hall effect,\nspin Nernst effect, and thermal Hall effect. Their magnetic states are also\nvery diverse: from a ferrimagnet and an antiferromagnet to a compensated\nferrimagnet and a frustrated antiferromagnet, as well as an antiferromagnet\nwith a kagome-type lattice. It has been demonstrated that the electronic and\nmagnetic properties of such materials are very sensitive to external influences\n(temperature, magnetic field, external pressure), as well as the processing\nmethod (cast, rapidly quenched, nanostructured, etc.). Knowledge of the\nregularities in the behavior of the electronic and magnetic characteristics of\nMn$_2$YAl and Mn$_3$Z compounds can be used for applications in micro- and\nnanoelectronics and spintronics."
    },
    {
        "anchor": "Representing Polymers as Periodic Graphs with Learned Descriptors for\n  Accurate Polymer Property Predictions: One of the grand challenges of utilizing machine learning for the discovery\nof innovative new polymers lies in the difficulty of accurately representing\nthe complex structures of polymeric materials. Although a wide array of\nhand-designed polymer representations have been explored, there has yet to be\nan ideal solution for how to capture the periodicity of polymer structures, and\nhow to develop polymer descriptors without the need for human feature design.\nIn this work, we tackle these problems through the development of our periodic\npolymer graph representation. Our pipeline for polymer property predictions is\ncomprised of our polymer graph representation that naturally accounts for the\nperiodicity of polymers, followed by a message-passing neural network (MPNN)\nthat leverages the power of graph deep learning to automatically learn\nchemically-relevant polymer descriptors. Across a diverse dataset of 10 polymer\nproperties, we find that this polymer graph representation consistently\noutperforms hand-designed representations with a 20% average reduction in\nprediction error. Our results illustrate how the incorporation of chemical\nintuition through directly encoding periodicity into our polymer graph\nrepresentation leads to a considerable improvement in the accuracy and\nreliability of polymer property predictions. We also demonstrate how combining\npolymer graph representations with message-passing neural network architectures\ncan automatically extract meaningful polymer features that are consistent with\nhuman intuition, while outperforming human-derived features. This work\nhighlights the advancement in predictive capability that is possible if using\nchemical descriptors that are specifically optimized for capturing the unique\nchemical structure of polymers.",
        "positive": "On the dynamics of spin systems with a general ground state: The paper is withdrawn by the author due to a recently discovered flaw in a\nbasic proof."
    },
    {
        "anchor": "Monolayer Fe$_{3}$GaX$_{2}$ (X=I, Br, Sb): high-temperature\n  two-dimensional magnets and a novel partially ordered spin state: We systematically investigated the effects of charge doping and strain on\nmonolayer Fe$_3$GaTe$_2$, and proposed three new novel two-dimensional magnetic\nmaterials: monolayer Fe$_3$GaX$_2$ (X=I, Br, Sb). We found that both strain and\ncharge doping can tune the magnetic interactions, and the tuning by charge\ndoping is more significant. Differential charge analysis revealed that the\ndoped charges predominantly accumulate around Te atoms. Based on this insight,\nwe introduced Fe$_{3}$GaI$_{2}$, Fe$_{3}$GaBr$_{2}$, and Fe$_{3}$GaSb$_{2}$\nmonolayers. The Fe$_{3}$GaI$_{2}$ and Fe$_{3}$GaBr$_{2}$ monolayers contain I\nand Br atoms rather than Te atoms, emulate electron-doped Fe$_{3}$GaTe$_{2}$\nmonolayer, resulting in notably high T$_c$ values of 867 K and 844 K,\nrespectively. In contrast, the Fe$_3$GaSb$_2$ monolayer mimics hole-doped\nFe$_{3}$GaTe$_{2}$ monolayer, presents a mix of FM and antiferromagnetic\ninteractions, manifesting a distinctive partially ordered magnetic state. Our\nstudy demonstrates that substitution atoms based on the charge-doping effect\noffer a promising approach for predicting new magnetic materials. The proposed\nFe$_{3}$GaI$_{2}$, Fe$_{3}$GaBr$_{2}$, and Fe$_{3}$GaSb$_{2}$ monolayers hold\ngreat potential for spintronics applications, and may stimulate the pursuit of\nnew types of spin liquid.",
        "positive": "Evolutionary optimization of a charge transfer ionic potential model for\n  Ta/Ta-oxide hetero-interfaces: Tantalum, tantalum oxide and their hetero-interfaces are of tremendous\ntechnological interest in several applications spanning electronics, thermal\nmanagement, catalysis and biochemistry. For example, local oxygen stoichiometry\nvariation in TaOx memristors comprising of metallic (Ta) and insulating oxide\n(Ta2O5) have been shown to result in fast switching on the sub-nanosecond\ntimescale over a billion cycles, relevant to neuromorphic computation. Despite\nits broad importance, an atomistic scale understanding of oxygen stoichiometry\nvariation across Ta/TaOx hetero-interfaces, such as during early stages of\noxidation and oxide growth, is not well understood. This is mainly due to the\nlack of a variable charge interatomic potential model for tantalum oxides that\ncan accurately describe the ionic interactions in the metallic (Ta) and oxide\n(TaOx) environment as well as at their interfaces. To address this challenge,\nwe introduce a charge transfer ionic potential (CTIP) model for Ta/Ta-oxide\nsystem by training against lattice parameters, cohesive energies, equations of\nstate, and elastic properties of various experimentally observed Ta2O5\npolymorphs. The best set of CTIP parameters are determined by employing a\nsingle-objective global optimization scheme driven by genetic algorithms\nfollowed by local Simplex optimization. Our newly developed CTIP potential\naccurately predicts structure, thermodynamics, energetic ordering of\npolymorphs, as well as elastic and surface properties of both Ta and Ta2O5, in\nexcellent agreement with DFT calculations and experiments. We employ our newly\nparameterized CTIP potential to investigate the early stages of oxidation of Ta\nat different temperatures and atomic/molecular nature of the oxidizing species."
    },
    {
        "anchor": "Concentration-Diversified Magnetic and Electronic Properties of\n  Halogen-Adsorbed Silicene: Diverse magnetic and electronic properties of halogen-adsorbed silicene are\ninvestigated by the first-principles theoretical framework, including the\nadatom-diversified geometric structures, the atom-dominated energy bands, the\nspatial spin density distributions, the spatial charge density distributions\nand its variations, and the spin- and orbital-projected density of states.\nAlso, such physical quantities are sufficient to identify similar and different\nfeatures in the double-side and single-side adsorptions. The former belongs to\nthe concentration-depended finite gap semiconductors or p-type metals, while\nthe latter display the valence energy bands with/without spin-splitting\nintersecting with the Fermi level. Both adsorption types show the\nhalogen-related weakly dispersed bands at deep energies, the adatom-modified\nmiddle-energy sigma bands, and the recovery of low-energy pi bands during the\ndestruction of the halogen concentrations. Such feature-rich band structures\ncan be verified by the angle-resolved photoemission spectroscopy experiment.",
        "positive": "A Self Healing Model Based on Polymer-Mediated Chromophore Correlations: Here we present a model of self healing in which correlations between\nchromophores, as mediated by the polymer, are key to the recovery process. Our\nmodel determines the size distribution of the correlation volume using a grand\ncanonical ensemble through a free energy advantage parameter. Choosing a\nhealing rate that is proportional to the number of undamaged molecules in a\ncorrelated region, and a decay rate proportional to the intensity normalized to\nthe correlation volume, the ensemble average is shown to correctly predict\ndecay and recovery of the population of disperse orange 11-DO11\n(1-amino-2-methylanthraquinone) molecules doped in PMMA polymer as a function\nof time and concentration as measured with amplified spontaneous emission and\nlinear absorption spectroscopy using only three parameters that apply to the\nfull set of data. Our model also predicts the temperature dependence of the\nprocess. One set of parameters should be characteristic of a particular polymer\nand dopant chromophore combination. Thus, use of the model in determining these\nparameters for various materials systems should provide the data needed to test\nfundamental models of the underlying mechanism responsible for self healing."
    },
    {
        "anchor": "Phase competition and negative piezoelectricity in interlayer-sliding\n  ferroelectric ZrI$_2$: The so-called interlayer-sliding ferroelectricity was recently proposed as an\nunconventional route to pursuit electric polarity in van der Waals\nmulti-layers, which was already experimentally confirmed in WTe$_2$ bilayer\neven though it is metallic. Very recently, another van der Waals system, i.e.,\nthe ZrI$_2$ bilayer, was predicted to exhibit the interlayer-sliding\nferroelectricity with both in-plane and out-of-plane polarizations [Phys. Rev.\nB \\textbf{103}, 165420 (2021)]. Here the ZrI$_2$ bulk is studied, which owns\ntwo competitive phases ($\\alpha$ \\textit{vs} $\\beta$), both of which are\nderived from the common parent $s$-phase. The $\\beta$-ZrI$_2$ owns a\nconsiderable out-of-plane polarization ($0.39$ $\\mu$C/cm$^2$), while its\nin-plane component is fully compensated. Their proximate energies provide the\nopportunity to tune the ground state phase by moderate hydrostatic pressure and\nuniaxial strain. Furthermore, the negative longitudinal piezoelectricity in\n$\\beta$-ZrI$_2$ is dominantly contributed by the enhanced dipole of ZrI$_2$\nlayers as a unique characteristic of interlayer-sliding ferroelectricity, which\nis different from many other layered ferroelectrics with negative longitudinal\npiezoelectricity like CuInP$_2$S$_6$.",
        "positive": "Density Functional Theory Evaluation of Cation-doped Bismuth Molybdenum\n  Oxide Photocatalysts for Nitrogen Fixation: This study investigates the photocatalytic nitrogen fixation on a\ncation-doped surface (Bi$_{x}$M$_{y}$)$_2$MoO$_6$ where (M = Fe, La, Yb) in\nboth the orthorhombic and monoclinic configurations using a density functional\ntheory (DFT) approach with experimentally validated model inputs. The\nproceeding discussion focuses on the Heyrovsky-type reactions for both the\nassociative and dissociative reaction pathway related to nitrogen reduction.\nKey fundamental insight in the reduction mechanism is discussed that relates\nthe material properties of the substitutional ions to the nitrogen and hydrogen\naffinities. Physical insight is gathered through interpretation of bound\nelectronic states at the surface. Compositional phases of higher Fe and Yb\nconcentrations resulted in decreased Mo-O binding and increased affinity\nbetween Mo and the N and H species on the surface. The modulation of the Mo-O\nbinding is induced by strain as Yb and Fe are implemented, this, in turn,\nshifts energy levels and modulates the band gap energy by approximately 0.2 eV.\nThis modification of Mo-O bond as substitution occurs is a result of the\norbital hybridization of M-O (M = Fe, Yb) that causes a strong orbital\ninteraction that shifts states. The optimal composition was predicted to be an\northorhombic configuration of (Bi$_{0.75}$Fe$_{0.25}$)$_2$MoO$_6$ with a\npredicted maximum thermodynamic energy barrier of 1.4 eV. This composition\ndemonstrates effective nitrogen and hydrogen affinity that follows the\nassociative or biological nitrogen fixation pathway."
    },
    {
        "anchor": "Single crystal growth and characterization of antiferromagnetically\n  ordering EuIn$_2$: We report the single crystal growth and characterization of EuIn$_2$, a\nmagnetic topological semimetal candidate according to our density functional\ntheory (DFT) calculations. We present results from electrical resistance,\nmagnetization, M\\\"ossbauer spectroscopy, and X-ray resonant magnetic scattering\n(XRMS) measurements. We observe three magnetic transitions at\n$T_{\\text{N}1}\\sim 14.2~$K, $T_{\\text{N}2}\\sim12.8~$K and $T_{\\text{N}3}\\sim\n11~$K, signatures of which are consistently seen in anisotropic temperature\ndependent magnetic susceptibility and electrical resistance data. M\\\"ossbauer\nspectroscopy measurements on ground crystals suggest an incommensurate\nsinusoidally modulated magnetic structure below the transition at\n$T_{\\text{N}1}\\sim 14~$K, followed by the appearance of higher harmonics in the\nmodulation on further cooling roughly below $T_{\\text{N}2}\\sim13~$K, before the\nmoment distribution squaring up below the lowest transition around\n$T_{\\text{N}3}\\sim 11~$K. XRMS measurements showed the appearance of magnetic\nBragg peaks below $T_{\\text{N}1}\\sim14~$K, with a propagation vector of\n$\\bm{\\tau}$ $=(\\tau_h,\\bar{\\tau}_h,0)$, with $\\tau_h$varying with temperature,\nand showing a jump at $T_{\\text{N}3}\\sim11$~K. The temperature dependence of\n$\\tau_h$ between $\\sim11$~K and $14$~K shows incommensurate values consistent\nwith the M\\\"{o}ssbauer data. XRMS data indicate that $\\tau_h$ remains\nincommensurate at low temperatures and locks into $\\tau_h=0.3443(1)$.",
        "positive": "Transmission and diffraction properties of a narrow slit in ideal metal: By solving Maxwell equations with the ideal-metal boundary conditions in the\nTM case, we have fully described the transmission and diffraction properties of\na single slit regardless of its width. Efficiencies of the main transformation\nprocesses -- transmission, diffraction, and reflection -- are analyzed in the\nsub-to-few-wavelength range showing a number of sharp fundamental features.\nClose links with the case of real metal are considered."
    },
    {
        "anchor": "Correlation between microstructural deformation mechanisms and acoustic\n  parameters on a cold-rolled Cu30Zn brass: The relationship between acoustic parameters and the microstructure of a\nCu30Zn brass plate subjected to plastic deformation was evaluated. The plate,\npreviously annealed at 550 {\\deg}C for 30 minutes, was cold rolled to\nreductions in the 10-70\\% range. Using the pulse-echo method, linear ultrasonic\nmeasurements were performed on each of the nine specimens, corresponding to the\nnine different reductions, recording the wave times of flight of longitudinal\nwave along the thickness axis. Subsequently, acoustic measurements were\nperformed to determine the nonlinear parameter ($\\beta$) through the second\nharmonic generation. X-ray diffraction analysis revealed a steady increase and\nsubsequent saturation of deformation twins at 40\\% thickness reduction. At\nhigher deformations, the microstructure revealed the generation and\nproliferation of shear bands, which coincided with a decrease in the twinning\nstructure and an increase in dislocation density rate. Longitudinal wave\nvelocity exhibited a 0.9\\% decrease at 20\\% deformation, followed by a\ncontinuous increase of 2\\% beyond this point. These results can be rationalized\nas a competition between a proliferation of dislocations, which tends to\ndecrease the linear sound velocity, and a decrease in average grain size, which\ntends to increase it. These variations are in agreement with the values\nobtained with XRD, Vickers hardness and metallography measurements. The\nnonlinear parameter $\\beta$ shows a significant maximum, at the factor of 8\nlevel, at 40\\% deformation. This maximum correlates well with a similar\nmaximum, at a factor of ten level and also at 40\\% deformation, of the twinning\nfault probability.",
        "positive": "Shapes for maximal coverage for two-dimensional random sequential\n  adsorption: The random sequential adsorption of various particle shapes is studied in\norder to determine the influence of particle anisotropy on the saturated random\npacking. For all tested particles there is an optimal level of anisotropy which\nmaximizes the saturated packing fraction. It is found that a concave shape\nderived from a dimer of disks gives a packing fraction of 0.5833, which is\ncomparable to the maximum packing fraction of ellipsoids and spherocylinders\nand higher than any other studied shape. Discussion why this shape is so\nbeneficial for random sequential adsorption is given."
    },
    {
        "anchor": "Coupling of carbon nanotubes to metallic contacts: The modeling of carbon nanotube-metal contacts is important from both basic\nand applied view points. For many applications, it is important to design\ncontacts such that the transmission is dictated by intrinsic properties of the\nnanotube rather than by details of the contact. In this paper, we calculate the\nelectron transmission probability from a nanotube to a free electron metal,\nwhich is side-contacted. If the metal-nanotube interface is sufficiently\nordered, we find that k-vector conservation plays an important role in\ndetermining the coupling, with the physics depending on the area of contact,\ntube diameter and chirality. The main results of this paper are: (i)\nconductance scales with contact length, a phenomena that has been observed in\nexperiments and (ii) in the case of uniform coupling between metal and\nnanotube, the threshold value of the metal Fermi wave vector (below which\ncoupling is insignificant) depends on chirality. Disorder and small phase\ncoherence length relax the need for k-vector conservation, thereby making the\ncoupling stronger.",
        "positive": "Manganese reduction/oxidation reaction on graphene composites as a\n  reversible process for storing enormous energy at a fast rate: Oxygen reduction/evolution reaction (ORR/OER) is a basic process for fuel\ncells or metal air batteries. However, ORR/OER generally requires noble metal\ncatalysts and suffers from low solubility (10-3 molar per liter) of O2, low\nkinetics rate (10-6 cm2/s) and low reversibility. We report a manganese\nreduction/oxidation reaction (MRR/MOR) on graphene/MnO2 composites, delivering\na high capacity (4200 mAh/g), fast kinetics (0.0024 cm2/s, three orders higher\nthan ORR/OER), high solubility (three orders than O2), and high reversibility\n(100%). We further use MRR/MOR to invent a rechargeable manganese ion battery\n(MIB), which delivers an energy density of 1200 Wh/Kg (several times of lithium\nion battery), a fast charge ability (3 minutes), and a long cycle life (10,000\ncycles). MRR/MOR renders a new class of energy conversion or storage systems\nwith a very high energy density enabling electric vehicles run much more miles\nat one charge."
    },
    {
        "anchor": "Microstructure Characterization and Reconstruction in Python: MCRpy: Microstructure characterization and reconstruction (MCR) is an important\nprerequisite for empowering and accelerating integrated computational materials\nengineering. Much progress has been made in MCR recently, however, in absence\nof a flexible software platform it is difficult to use ideas from other\nresearchers and to develop them further. To address this issue, this work\npresents MCRpy for easy-to-use, extensible and flexible MCR. The software\nplatform that can be used as a program with graphical user interface, as a\ncommand line tool and as a Python library. The central idea is that\nmicrostructure reconstruction is formulated as a modular and extensible\noptimization problem. In this way, any descriptors can be used for\ncharacterization and any loss function combining any descriptors can be\nminimized using any optimizer for reconstruction. With stochastic optimizers,\nthis leads to variations of the well-known Yeong-Torquato algorithm.\nFurthermore, MCRpy features automatic differentiation, enabling the utilization\nof gradient-based optimizers. In this work, after a brief introduction to the\nunderlying concepts, the capabilities of MCRpy are demonstrated by exemplarily\napplying it to typical MCR tasks. Finally, it is shown how to extend MCRpy by\ndefining a new microstructure descriptor and readily using it for\nreconstruction without additional implementation effort.",
        "positive": "Molecular Dynamics Simulation of Chemical Vapor Deposition of Amorphous\n  Carbon: Dependence on H/C Ratio of Source Gas: By molecular dynamics simulation, the chemical vapor deposition of amorphous\ncarbon onto graphite and diamond surfaces was studied. In particular, we\ninvestigated the effect of source H/C ratio, which is the ratio of the number\nof hydrogen atoms to the number of carbon atoms in a source gas, on the\ndeposition process. In the present simulation, the following two source gas\nconditions were tested: one was that the source gas was injected as isolated\ncarbon and hydrogen atoms, and the other was that the source gas was injected\nas hydrocarbon molecules. Under the former condition, we found that as the\nsource H/C ratio increases, the deposition rate of carbon atoms decreases\nexponentially. This exponential decrease in the deposition rate with increasing\nsource H/C ratio agrees with experimental data. However, under the latter\nmolecular source condition, the deposition rate did not decrease exponentially\nbecause of a chemical reaction peculiar to the type of hydrocarbon in the\nsource gas."
    },
    {
        "anchor": "Computational Design of the Rare-Earth Reduced Permanent Magnets: Multiscale simulation is a key research tool for the quest for new permanent\nmagnets. Starting with first principles methods, a sequence of simulation\nmethods can be applied to calculate the maximum possible coercive field and\nexpected energy density product of a magnet made from a novel magnetic material\ncomposition. Fe-rich magnetic phases suitable for permanent magnets can be\nfound by adaptive genetic algorithms. The intrinsic properties computed by ab\ninitio simulations are used as input for micromagnetic simulations of the\nhysteresis properties of permanent magnets with realistic structure. Using\nmachine learning techniques, the magnet's structure can be optimized so that\nthe upper limits for coercivity and energy density product for a given phase\ncan be estimated. Structure property relations of synthetic permanent magnets\nwere computed for several candidate hard magnetic phases. The following pairs\n(coercive field (T), energy density product (kJ/m3)) were obtained for\nFe3Sn0.75Sb0.25: (0.49, 290), L10 FeNi: (1, 400), CoFe6Ta: (0.87, 425), and\nMnAl: (0.53, 80).",
        "positive": "Machine learning assisted prediction of organic salt structure\n  properties: We demonstrate a machine learning-based approach which predicts the\nproperties of crystal structures following relaxation based on the unrelaxed\nstructure. Use of crystal graph singular values reduces the number of features\nrequired to describe a crystal by more than an order of magnitude compared to\nthe full crystal graph representation. We construct machine learning models\nusing the crystal graph singular value representations in order to predict the\nvolume, enthalpy per atom, and metal versus semiconducting phase of DFT-relaxed\norganic salt crystals based on randomly generated unrelaxed crystal structures.\nInitial base models are trained to relate 89,949 randomly generated structures\nof salts formed by varying ratios of 1,3,5-triazine and HCl with the\ncorresponding volumes, enthalpies per atom, and phase of the DFT-relaxed\nstructures. We further demonstrate that the base model is able to extrapolate\nto new chemical systems with the inclusion of 2,000 to 10,000 crystal\nstructures from the new system. After training a single model with a large\nnumber of data points, extension can be done at significantly lower cost. The\nconstructed machine learning models can be used to rapidly screen large sets of\nrandomly generated organic salt crystal structures and efficiently downselect\nthe structures most likely to be experimentally realizable. The models can be\nused either as a stand-alone crystal structure predictor or incorporated into\nmore sophisticated workflows as a filtering step."
    },
    {
        "anchor": "Mechanisms and kinetics of C-S-H nucleation approaching the spinodal\n  line: Insights into the role of organics additives: Wet chemistry C-S-H precipitation experiments were performed under controlled\nconditions of solution supersaturation in the presence and absence of gluconate\nand three hexitol molecules. Characterization of the precipitates with SAXS and\ncryo-TEM experiments confirmed the presence of a multi-step nucleation pathway.\nInduction times for the formation of the amorphous C-S-H spheroids were\ndetermined from light transmittance. Analysis of those data with the classical\nnucleation theory revealed a significant increase of the kinetic prefactor in\nthe same order as the complexation constants of calcium and silicate with each\nof the organics. Finally, two distinct precipitation regimes of the C-S-H\namorphous precursor were identified: i) a nucleation regime at low saturation\nindexes (SI) and ii) a spinodal nucleation regime at high SI where the free\nenergy barrier to the phase transition is found to be of the order of the\nkinetic energy or less.",
        "positive": "TCO Nanostructures as building blocks for nanophotonic devices in the\n  infrared: Transparent conducting oxides (TCOs), in general, are degenerated\nsemiconductors with large electronic band-gap. They have been widely used for\ndisplay screens, optoelectronic, photonic, and photovoltaic devices due to\ntheir unique dual transparent and conductive properties. In this study, we\nreport in detail a technique that we developed to fabricate single crystal TCO\nnanorod arrays with controlled conductivity, height, and lattice spacing in a\nsimple one-zone tube furnace system. We demonstrate how novel\nphotonic/plasmonic properties can be obtained by selecting unique combinations\nof these basic parameters of the nano-rod arrays."
    },
    {
        "anchor": "Theory of strain tunning exction coupling in self-assembled InAs/GaAs\n  quantum dots: We derive analytically the change of exciton fine structure splitting (FSS)\nunder the external stresses in the self-assembled InAs/GaAs quantum dots using\nthe Bir-Pikus model. We find that the FSS change is mainly due to the strain\ninduced valence bands mixing and valence-conduction band coupling. The exciton\npolarization angle under strain are determined by the argument of the\nelectron-hole off-diagonal exchange integrals. The theory agrees well with the\nempirical pseudopotential calculations.",
        "positive": "Intragranular nucleation of tetrahedral precipitates and discontinuous\n  precipitation in Cu-5wt%Ag: Both continuous and discontinuous precipitation is known to occur in CuAg\nalloys. The precipitation of Ag-rich phase has been experimentally investigated\nby atom probe tomography and transmission electron microscopy after ageing\ntreatment of Cu-5%wtAg at 440$^\\circ$C during 30'. Both continuously and\ndiscontinuously formed precipitates have been observed. The precipitates\nlocated inside the grains exhibit two different faceted shapes: tetrahedral and\nplatelet-shaped precipitates. Dislocations accommodating the high misfit at the\ninterface between the two phases have also been evidenced. Based on these\nexperimental observations, we examine the thermodynamic effect of these\ndislocations on the nucleation barrier and show that the peculiar shapes are\ndue to the interfacial anisotropy. The appropriate number of misfit\ndislocations relaxes the elastic stress and lead to energetically favorable\nprecipitates. However, due to the large misfit between the parent and\nprecipitate phases, discontinuous precipitation that is often reported for CuAg\nalloys can be a lower energetic path to transform the supersaturated solid\nsolution. We suggest that the presence of vacancy clusters may assist\nintragranular nucleation and decrease"
    },
    {
        "anchor": "Magnetic phase diagram of $A_{2}$[FeCl$_{5}$(H$_{2}$O)] ($A$ = K, Rb,\n  NH$_{4}$): Erythrosiderites with the formula A2FeX5H2O, where A = Rb, K, and (NH4) and X\n= Cl and Br are intriguing systems that possess various magnetic and electric\nphases, as well as multiferroic phases in which magnetism and ferroelectricity\nare coupled. In this report, we study the magnetic phase diagram of\nerythrosiderites as a function of superexchange interactions. To this end, we\nperform classical Monte Carlo simulations on magnetic Hamiltonians that contain\nfive different superexchange interactions with single-ion anisotropies. Our\nphase diagram contains all magnetic ground states that have been experimentally\nobserved in these materials. We argue that the ground states can be explained\nby varying the ratio of J4/J2. For J4/J2 > 0.95 a cycloidal spins structure is\nstabilized as observed in (NH4)2FeCl5H2O and otherwise, a collinear spin\nstructure is stabilized as observed in (K,Rb)2FeCl5H2O. We also show that the\ndifference in the single-ion anisotropy along a- and c- axes is essential to\nstabilize the intermediate state observed in (NH)2FeCl5H2O.",
        "positive": "Multilayer Adsorption of Polyatomic Species on Homogeneous and\n  Heterogeneous Surfaces: In this work we study the multilayer adsorption of polyatomic species on\nhomogeneous and heterogeneous bivariate surfaces. A new approximate analytic\nisotherm is obtained and validated by comparing with Monte Carlo simulation.\nThen, we use the well-known Brunauer-Emmet-Teller's (BET) approach to analyze\nthese isotherms and to estimate the monolayer volume, $v_\\mathrm{m}$. The\nresults show that the value of the $v_\\mathrm{m}$ obtained in this way depends\nstrongly on adsorbate size and surface topography. In all cases, we find that\nthe use of the BET equation leads to an underestimate of the true monolayer\ncapacity."
    },
    {
        "anchor": "Ab initio investigation of H-bond disordering in $\u03b4$-AlOOH: $\\delta$-AlOOH ($\\delta$) is a high-pressure hydrous phase that participates\nin the deep geological water cycle. At 0 GPa, $\\delta$ has asymmetric hydrogen\nbonds (H-bonds). Under pressure, it exhibits H-bond disordering, tunneling, and\nfinally, H-bond symmetrization at ~18 GPa. This study investigates these 300 K\npressure-induced state changes in $\\delta$ with ab initio calculations. H-bond\ndisordering in $\\delta$ was modeled using supercell multi-configuration\nquasiharmonic calculations. We examine: (a) energy barriers for proton jumps,\n(b) the pressure dependence of phonon frequencies, (c) 300 K compressibility,\n(d) neutron diffraction pattern anomalies, and (e) compare ab initio bond\nlengths with measured ones. Such thorough and systematic comparisons indicate\nthat: (a) proton \"disorder\" has a restricted meaning when applied to $\\delta$.\nNevertheless, H-bonds are disordered between 0 and 8 GPa, and a gradual change\nin H-bond configuration results in enhanced compressibility. (b) several\nstructural and vibrational anomalies at ~8 GPa are consistent with the\ndisappearance of a particular (HOC-12) H-bond configuration and its change into\nanother one (HOC-11*). (c) between 8-11 GPa, H-bond configuration (HOC-11*) is\ngenerally ordered, at least in short- to mid-range scale. (d) between 11.5-18\nGPa, H-bond lengths approach a critical value that impedes compression,\nresulting in decreased compressibility. In this pressure range, especially\napproaching H-bond symmetrization at ~18 GPa, anharmonicity and tunneling\nshould play an essential role in the proton dynamics. Further simulations\naccounting for these effects are desirable to clarify the protons' state in\nthis pressure range.",
        "positive": "Electronic structure and spectral properties of Am, Cm and Bk: Charge\n  density self-consistent LDA+HIA calculations in FP-LAPW basis: We provide a straightforward and numerically efficient procedure to perform\nlocal density approximation + Hubbard I (LDA+HIA) calculations, including\nself-consistency over the charge density, within the full potential linearized\naugmented plane wave (FP-LAPW) method. This implementation is all-electron,\nincludes spin-orbit interaction, and makes no shape approximations for the\ncharge density. The method is applied to calculate selected heavy actinides in\nthe paramagnetic phase. The electronic structure and spectral properties of Am\nand Cm metals obtained are in agreement with previous dynamical mean-field\ntheory (LDA+DMFT) calculations and with available experimental data. We point\nout that the charge density self-consistent LDA+HIA calculations predict the\n$f$ charge on Bk to exceed the atomic integer $f^8$ value by 0.22."
    },
    {
        "anchor": "Role of planar buckling on the electronic, thermal, and optical\n  properties of Germagraphene nanosheets: We report the electronic, the thermal, and the optical properties of a\nGermagraphene (GeC) monolayer taking into account buckling effects. The\nrelatively wide direct band gap of a flat GeC nanosheet can be changed by\ntuning the planar buckling. A GeC monolayer has an sp$^2$ hybridization in\nwhich the contribution of an $s$-orbital is half of the contribution of a\n$p$-orbital leading to stronger $\\sigma\\text{-}\\sigma$ bonds compared to the\n$\\sigma\\text{-}\\pi$ bonds. Increasing the planar buckling, the contribution of\nan $s$-orbital is decreased while the contribution of a $p$-orbital is\nincreased resulting in a sp$^3$-hybridization in which the $\\sigma\\text{-}\\pi$\nbond becomes stronger than the $\\sigma\\text{-}\\sigma$ bond. As a result, the\nband gap of a buckled GeC is reduced and thus the thermal and the optical\nproperties are significantly modified. We find that the heat capacity of the\nbuckled GeC is decreased at low values of planar buckling, which is caused by\nthe anticrossing of the optical and the acoustic phonon modes affecting phonon\nscattering processes. The resulting optical properties, such as the dielectric\nfunction, the refractive index, the electron energy loss spectra, the\nabsorption, and the optical conductivity show that a buckled GeC nanosheet has\nincreased optical activities in the visible light region compared to a flat\nGeC. The optical conductivity is red shifted from the near ultraviolet to the\nvisible light region, when the planar buckling is increased. We can thus\nconfirm that the buckling can be seen as another parameter to improve GeC\nmonolayers for optoelectronic devices.",
        "positive": "Stability of multivacancies in graphene: The stability of graphene multivacancy systems is studied using Density\nFunctional Theory (DFT) calculations. This work describes the evolution of the\nenergy of formation per carbon atom for zigzag and armchair complementary\nfigures -i.e. the figure formed by the carbon atoms extracted from graphene to\nform the vacancy-. Multivacancy systems formed when armchair complementary\nfigures are removed are more stable for higher orders (>5) in comparison with\nthe zigzag ones. The case of the construction of a 6-order vacancy from a\n5-order one (branch-like) is discussed with the dependence on the place where\nthe extra carbon atom is removed from graphene. The stability of multivacancy\nsystems could be explained through the relative positions of the pentagonal\nrings present in the resulting defected graphene structure, as the more\nrelevant factor. Other secondary factors that affect the stability of a\ngraphene multivacancy system are the dangling bonds magnetic arrangements and\ntheir steric hindrance."
    },
    {
        "anchor": "Atomic scale mapping of impurities in partially reduced hollow TiO2\n  nanowires: The incorporation of impurities during the chemical synthesis of\nnanomaterials is usually uncontrolled and rarely reported because of the\nformidable challenge that constitutes measuring trace amounts of often light\nelements with sub nanometre spatial resolution. Yet these foreign elements\ninfluence functional properties, by e.g. doping. Here we demonstrate how the\nsynthesis and partial reduction reaction on hollow TiO2 nanowires leads to the\nintroduction of parts-per-millions of boron, sodium, and nitrogen from the\nreduction reaction with sodium borohydride at the surface of the TiO2 nanowire.\nThis doping explains the presence of oxygen vacancies at the surface that\nenhance the activity. Our results obtained on model metal-oxide nanomaterials\nshed light on the general process leading to the uncontrolled incorporation of\ntrace impurities that can have a dramatic effect on their potential use in\nenergy-harvesting applications.",
        "positive": "Narrow-gap Semiconducting Superhard Amorphous Carbon with Superior\n  Toughness: New carbon forms exhibiting extraordinary physico-chemical properties can be\ngenerated from nanostructured precursors under extreme pressure. Nevertheless,\nsynthesis of such fascinating materials is often not well understood that\nresults, as is the case of C60 precursor, in irreproducibility of the results\nand impeding further progress in the materials design. Here the semiconducting\namorphous carbon having bandgaps of 0.1-0.3 eV and the advantages of isotropic\nsuperhardness and superior toughness over single-crystal diamond and inorganic\nglasses are produced from transformation of fullerene at high pressure and\nmoderate temperatures. A systematic investigation of the structure and bonding\nevolution was carried out by using rich arsenal of complimentary\ncharacterization methods, which helps to build a model of the transformation\nthat can be used in further high p,T synthesis of novel nanocarbon systems for\nadvanced applications. The produced amorphous carbon materials have the\npotential of demanding optoelectronic applications that diamond and graphene\ncannot achieve"
    },
    {
        "anchor": "Electrical properties of boron-doped MWNTs synthesized by hot-filament\n  chemical vapor deposition: We have synthesized a large amount of boron-doped multiwalled carbon\nnanotubes (MWNTs) by hot-filament chemical vapor deposition. The synthesis was\ncarried out in a flask using a methanol solution of boric acid as a source\nmaterial. The scanning electron microscopy, transmission electron microscopy,\nand micro-Raman spectroscopy were performed to evaluate the structural\nproperties of the obtained MWNTs. In order to evaluate the electrical\nproperties, temperature dependence of resistivity was measured in an individual\nMWNTs with four metal electrodes. The Ramman shifts suggest carrier injection\ninto the boron-doped MWNTs, but the resistivity of the MWNTs was high and\nincreased strongly with decreasing temperature. Defects induced by the plasma\nmay cause this enhanced resistivity.",
        "positive": "Discovery and construction of surface kagome electronic states induced\n  by p-d electronic hybridization: Kagome-lattice materials possess attractive properties for quantum computing\napplications, but their synthesis remains challenging. Herein, we show surface\nkagome electronic states (SKESs) on a Sn-terminated triangular Co3Sn2S2\nsurface, which are imprinted by vertical p-d electronic hybridization between\nthe surface Sn (subsurface S) atoms and the buried Co kagome lattice network in\nthe Co3Sn layer under the surface. Owing to the subsequent lateral\nhybridization of the Sn and S atoms in a corner-sharing manner, the kagome\nsymmetry and topological electronic properties of the Co3Sn layer is proximate\nto the Sn surface. The SKESs and both hybridizations were verified via qPlus\nnon-contact atomic force microscopy (nc-AFM) and density functional theory\ncalculations. The construction of SKESs with tunable properties can be achieved\nby the atomic substitution of surface Sn (subsurface S) with other group III-V\nelements (Se or Te), which was demonstrated theoretically. This work exhibits\nthe powerful capacity of nc-AFM in characterizing localized topological states\nand reveals the strategy for synthesis of large-area transition-metal-based\nkagome lattice materials using conventional surface deposition techniques."
    },
    {
        "anchor": "Process Optimization and Downscaling of a Single Electron Single Dot\n  Memory: This paper presents the process optimization of a single-electron nanoflash\nelectron memory. Self-aligned single dot memory structures have been fabricated\nusing a wet anisotropic oxidation of a silicon nanowire. One of the main issue\nwas to clarify the process conditions for the dot formation. Based on the\nprocess modeling, the influence of various parameters (oxidation temperature,\nnanowire shape) has been investigated. The necessity of a sharp compromise\nbetween these different parameters to ensure the presence of the memory dot has\nbeen established. In order to propose an aggressive memory cell, the\ndownscaling of the device has been carefully studied. Scaling rules show that\nthe size of the original device could be reduced by a factor of 2. This point\nhas been previously confirmed by the realization of single-electron memory\ndevices.",
        "positive": "Measurement and modeling of the mechanical and electrochemical response\n  of amorphous Si thin film electrodes during cyclic lithiation: A combination of experimental measurements and numerical simulations are used\nto characterize the mechanical and electrochemical response of thin film\namorphous Si electrodes during cyclic lithiation. Parameters extracted from the\nexperiment include the variation of elastic modulus and the flow stress as\nfunctions of Li concentration; the strain rate sensitivity; the diffusion\ncoefficient for Li transport in the electrode; the free energy of mixing as a\nfunction of Li concentration in the electrode; the exchange current density for\nthe Lithium insertion reaction; as well as reaction rates and diffusion\ncoefficients characterizing the rate of formation of solid-electrolyte\ninterphase layer at the electrode surface. Model predictions are compared with\nexperimental measurements; and the implications for practical Si based\nelectrodes are discussed."
    },
    {
        "anchor": "Picometer-scale atom position analysis in annular bright-field STEM\n  imaging: We study the effects of specimen mistilt on the picometer-scale measurement\nof local structure by combing experiment and simulation in annular bright-field\nscanning transmission electron microscopy (ABF-STEM). A relative distance\nmeasurement method is proposed to separate the tilt effects from the scan noise\nand scan distortion. We find that under a typical experimental condition a\nsmall specimen tilt (~6 mrad) in 25 nm thick SrTiO3 along [001] causes 11.9 pm\nartificial displacement between O and Sr/TiO columns in ABF image, which is\nmore than 3 times of scan noise and sample drift induced image distortion ~3.2\npm, suggesting the tilt effect could be dominant for the quantitative analysis\nof ABF images. The artifact depends the crystal mistilt angle, specimen\nthickness, defocus, convergence angle and uncorrected aberration. Our study\nprovides useful insights into detecting and correcting tilt effects during both\nexperiment operation and data analysis to extract the real structure\ninformation and avoid mis-interpretations of atomic structure as well as the\nproperties such as oxygen octahedral distortion/shift.",
        "positive": "Experimental and theoretical evidences for the ice regime in planar\n  artificial spin ices: In this work, we explore a kind of geometrical effect in the thermodynamics\nof artificial spin ices (ASI). In general, such artificial materials are\nathermal. Here, We demonstrate that geometrically driven dynamics in ASI can\nopen up the panorama of exploring distinct ground states and thermally magnetic\nmonopole excitations. It is shown that a particular ASI lattice will provide a\nricher thermodynamics with nanomagnet spins experiencing less restriction to\nflip precisely in a kind of rhombic lattice. This can be observed by analysis\nof only three types of rectangular artificial spin ices (RASI). Denoting the\nhorizontal and vertical lattice spacings by a and b, respectively, then, a RASI\nmaterial can be described by its aspect ratio $\\gamma$=a/b. The rhombic lattice\nemerges when $\\gamma$=$\\sqrt{3}$. So, by comparing the impact of thermal\neffects on the spin flips in these three appropriate different RASI arrays, it\nis possible to find a system very close to the ice regime."
    },
    {
        "anchor": "On the average charge of the oxygen vacancy in perovskites necessary for\n  kinetic calculations: An analytical result has been obtained for the value of the dynamical charge\nnecessary for calculations of oxygen vacancy kinetics in dielectric\nperovskite-type crystals. It is shown by using the Berry phase analysis that\nthis charge equals the nominal charge of the vacancy: for example, for the\ndouble charged state, it is 2; a neutral vacancy has the zero charge.",
        "positive": "Quasi-free-standing AA-stacked bilayer graphene induced by calcium\n  intercalation of the graphene-silicon carbide interface: We study quasi-freestanding bilayer graphene on silicon carbide intercalated\nby calcium. The intercalation, and subsequent changes to the system, were\ninvestigated by low-energy electron diffraction, angle-resolved photoemission\nspectroscopy (ARPES) and density-functional theory (DFT). Calcium is found to\nintercalate only at the graphene-SiC interface, completely displacing the\nhydrogen terminating SiC. As a consequence, the system becomes highly n-doped.\nComparison to DFT calculations shows that the band dispersion, as determined by\nARPES, deviates from the band structure expected for Bernal-stacked bilayer\ngraphene. Instead, the electronic structure closely matches AA-stacked bilayer\ngraphene on Ca-terminated SiC, indicating a spontaneous transition from AB- to\nAA-stacked bilayer graphene following calcium intercalation of the underlying\ngraphene-SiC interface."
    },
    {
        "anchor": "On the Mechanical, Electronic, and Optical Properties of 8-16-4\n  Graphyne: A 2D Carbon Allotrope with Dirac Cones: Due to the success achieved by graphene, several 2D carbon-based allotropes\nwere theoretically predicted and experimentally synthesized. We used density\nfunctional theory and reactive molecular dynamics simulations to investigate\nthe mechanical, structural, electronic, and optical properties of 8-16-4\nGraphyne. The results showed that this material exhibits good dynamical and\nthermal stabilities. Its formation energy and elastic moduli are -8.57 eV/atom\nand 262.37 GPa, respectively. This graphyne analogue is a semi-metal and\npresents two Dirac cones in its band structure. Moreover, it is transparent,\nand its intense optical activity is limited to the infrared region. Remarkably,\nthe band structure of 8-16-4 Graphyne remains practically unchanged at even\nmoderate strain regimes. As far as we know, this is the first 2D carbon\nallotrope to exhibit this behavior.",
        "positive": "Magnon-bandgap controllable artificial domain wall waveguide: In this paper, a magnon-bandgap controllable artificial domain wall waveguide\nis proposed by means of micromagnetic simulation. By the investigation of the\npropagation behavior and dispersion relationship of spin waves in artificial\ndomain wall waveguides, it is found that the nonreciprocal propagation of spin\nwaves in the artificial domain walls are mainly affected by the local effective\nexchange field, and the magnon bandgap can be controlled by changing the\nmaximum value of the effective exchange field. In addition, it is observed that\nthe artificial domain wall waveguides are structurally more stable than the\nnatural domain wall waveguides under the same spin wave injection conditions,\nand the magnon bandgap of the artificial domain wall waveguides can be adjusted\nby its width and magnetic anisotropy parameters. The bandgap controllable\nartificial domain wall scheme is beneficial to the miniaturization and\nintegration of magnon devices and can be applied to future magnonic technology\nas a novel frequency filter."
    },
    {
        "anchor": "HAADF-STEM Study of Mo/V Distributions in Mo-V-Te-Ta-O M1 Phases and\n  Their Correlations with Surface Reactivity: The MoVTeTaO M1 phases were prepared by conventional hydrothermal (HT) and\nmicrowave-assisted HT synthesis methods (MW) employing two different Ta\nprecursors, Ta ethoxide and a custom-made Ta oxalate complex. The profile\nintensity analysis of the HAADF-STEM image of M1 phases oriented along [hk0]\ndirections from the surface to bulk region of HAADF-STEM images indicated that\nthe chemical composition of surface ab planes is very similar to their\ncomposition in the bulk. The HAADF-STEM image analysis showed that synthesis\nmethods have a significant impact on the Mo/V distribution in the MoVTeTaO M1\nphases and their reactivity in propane ammoxidation. Enhanced acrylonitrile\n(ACN) yield and 1st order irreversible reaction rate constants for propane\nconsumption, normalized to the estimated surface ab plane areas, correlated\nwith increased V content in the proposed catalytic center (S2-S4-S4-S7-S7).\nThese observations lend further support to the idea that multiple VOx sites\npresent in the surface ab planes may be responsible for the activity and\nselectivity of the M1 phase in propane ammoxidation.",
        "positive": "Microfocus laser-ARPES on encapsulated mono-, bi-, and few-layer\n  1T'-WTe$_2$: Two-dimensional crystals of semimetallic van der Waals materials hold much\npotential for the realization of novel phases, as exemplified by the recent\ndiscoveries of a polar metal in few layer 1T'-WTe$_2$ and of a quantum spin\nHall state in monolayers of the same material. Understanding these phases is\nparticularly challenging because little is known from experiment about the\nmomentum space electronic structure of ultrathin crystals. Here, we report\ndirect electronic structure measurements of exfoliated mono-, bi-, and\nfew-layer 1T'-WTe$_2$ by laser-based micro-focus angle resolved photoemission.\nThis is achieved by encapsulating with monolayer graphene a flake of WTe$_2$\ncomprising regions of different thickness. Our data support the recent\nidentification of a quantum spin Hall state in monolayer 1T'-WTe$_2$ and reveal\nstrong signatures of the broken inversion symmetry in the bilayer. We finally\ndiscuss the sensitivity of encapsulated samples to contaminants following\nexposure to ambient atmosphere."
    },
    {
        "anchor": "Solute effects on interfacial dislocation emission in nanomaterials:\n  nucleation site competition and neutralization: Interfacial nucleation is the dominant process of dislocation generation\nduring the plastic deformation of nano-crystalline materials. Solute additions\nintended to stabilize nano-crystalline metals against grain growth, may\nsegregate to the grain boundaries and triple junctions where they can affect\nthe process of the dislocation emission. In this Letter we demonstrate that the\neffect of solute addition in a nano-crystalline material containing competing\nsolute segregation sites and dislocation sources can be very complex due to\ndifferent rates of segregation at different interfaces. Moreover, at large\nconcentrations, when the solutes form clusters near the grain boundaries or\ntriple junctions, the interfaces between these clusters and the matrix can\nintroduce new dislocation emission sources, which can be activated under lower\napplied stress. Thus, the strength maximum can occur at a certain solute\nconcentration: adding solutes beyond this optimal solute concentration can\nreduce the strength of the material.",
        "positive": "A probabilistic explanation for the size-effect in crystal plasticity: In this work, the well known power-law relation between strength and sample\nsize, $d^{-n}$, is derived from the knowledge that a dislocation network\nexhibits scale-free behaviour and the extreme value statistical properties of\nan arbitrary distribution of critical stresses. This approach yields\n$n=(\\tau+1)/(\\alpha+1)$, where $\\alpha$ reflects the leading order algebraic\nexponent of the low stress regime of the critical stress distribution and\n$\\tau$ is the scaling exponent for intermittent plastic strain activity. This\nquite general derivation supports the experimental observation that the size\neffect paradigm is applicable to a wide range of materials, differing in\ncrystal structure, internal microstructure and external sample geometry."
    },
    {
        "anchor": "The role of defects in the etching of graphene by intercalated oxygen: Graphene is one of the most promising 2D materials for various applications\ndue to its unique electronic properties and high thermal stability. In previous\nstudies, it was shown that when graphene is deposited onto some transition\nmetal substrates, small molecules, such as O$_2$, intercalate between the\ngraphene and the substrate and react to partially etch the graphene film when\nheated to desorb the intercalates. Here, carbon vacancy defects are\nintentionally formed on Gr/Ru(0001) and their effect on the intercalation of\noxygen and etching of the graphene layer are investigated. 50 eV Ar$^+$\nsputtering with a low fluence is used to create isolated single vacancy defects\nin the graphene overlayer and helium low energy ion scattering (LEIS) is\nemployed for surface analysis. It is found that the defects both ease the\nintercalation of the oxygen molecules and improve the etching efficiency of the\ngraphene during annealing.",
        "positive": "Torsional moduli of transition metal dichalcogenide nanotubes from first\n  principles: We calculate the torsional moduli of single-walled transition metal\ndichalcogenide (TMD) nanotubes using ab initio density functional theory (DFT).\nSpecifically, considering forty-five select TMD nanotubes, we perform\nsymmetry-adapted DFT calculations to calculate the torsional moduli for the\narmchair and zigzag variants of these materials in the low-twist regime and at\npractically relevant diameters. We find that the torsional moduli follow the\ntrend: MS$_2$ $>$ MSe$_2$ $>$ MTe$_2$. In addition, the moduli display a power\nlaw dependence on diameter, with the scaling generally close to cubic, as\npredicted by the isotropic elastic continuum model. In particular, the shear\nmoduli so computed are in good agreement with those predicted by the isotropic\nrelation in terms of the Young's modulus and Poisson's ratio, both of which are\nalso calculated using symmetry-adapted DFT. Finally, we develop a linear\nregression model for the torsional moduli of TMD nanotubes based on the\nnature/characteristics of the metal-chalcogen bond, and show that it is capable\nof making reasonably accurate predictions."
    },
    {
        "anchor": "High-temperature structural phase transition in multiferroic LiCu_2O_2: LiCu_2O_2 single crystals were studied in the temperature range 300-1100 K by\nmeans of heating-cooling curves of differential thermal analysis (DTA),\nthermogravimetry (TG), X-ray powder diffraction and electrical measurements. A\nreversible first-order phase transition between orthorhombic and tetragonal\nphases was found to take place at 993 K. At the transition, a peak is observed\nin the DTA curves, as well as jumps of the unit cell parameters and electrical\nresistivity. Considering the crystal structure of LiCu_2O_2 and the entropy\nchange associated with the phase transition, it is concluded that the phase\ntransition is related to processes of order-disorder of the Cu2+ and Li+\ncations onto their crystallographic positions.",
        "positive": "Intervalley plasmons in crystals: Collective charge excitations in solids have been the subject of intense\nresearch ever since the pioneering works of Bohm and Pines in the 1950s. Most\nof these studies focused on long-wavelength plasmons that involve charge\nexcitations with a small crystal-momentum transfer, $q \\ll G$, where $G$ is the\nwavenumber of a reciprocal lattice vector. Less emphasis was given to\ncollective charge excitations that lead to shortwave plasmons in multivalley\nelectronic systems (i.e., when $q \\sim G$). We present a theory of intervalley\nplasmons, taking into account local-field effects in the dynamical dielectric\nfunction. Focusing on monolayer transition-metal dichalcogenides where each of\nthe valleys is further spin-split, we derive the energy dispersion of these\nplasmons and their interaction with external charges. Emphasis in this work is\ngiven to sum rules from which we derive the interaction between intervalley\nplasmons and a test charge, as well as a compact single-plasmon pole expression\nfor the dynamical Coulomb potential."
    },
    {
        "anchor": "Position-controlled functionalization of vacancies in silicon by\n  single-ion implanted germanium atoms: Special point defects in semiconductors have been envisioned as suitable\ncomponents for quantum-information technology. The identification of new deep\ncenters in silicon that can be easily activated and controlled is a main target\nof the research in the field. Vacancy-related complexes are suitable to provide\ndeep electronic levels but they are hard to control spatially. With the spirit\nof investigating solid state devices with intentional vacancy-related defects\nat controlled position, here we report on the functionalization of silicon\nvacancies by implanting Ge atoms through single-ion implantation, producing\nGe-vacancy (GeV) complexes. We investigate the quantum transport through an\narray of GeV complexes in a silicon-based transistor. By exploiting a model\nbased on an extended Hubbard Hamiltonian derived from ab-initio results we find\nanomalous activation energy values of the thermally activated conductance of\nboth quasi-localized and delocalized many-body states, compared to conventional\ndopants. We identify such states, forming the upper Hubbard band, as\nresponsible of the experimental sub-threshold transport across the transistor.\nThe combination of our model with the single-ion implantation method enables\nfuture research for the engineering of GeV complexes towards the creation of\nspatially controllable individual defects in silicon for applications in\nquantum information technologies.",
        "positive": "Thermal conductivity of the thermoelectric layered cobalt oxides\n  measured by the Harman method: In-plane thermal conductivity of the thermoelectric layered cobalt oxides has\nbeen measured using the Harman method, in which thermal conductivity is\nobtained from temperature gradient induced by applied current. We have found\nthat the charge reservoir block (the block other than the CoO$_2$ block)\ndominates the thermal conduction, where a nano-block integration concept is\neffective for material design. We have further found that the thermal\nconductivity shows a small but finite in-plane anisotropy between $a$ and $b$\naxes, which can be ascribed to the misfit structure."
    },
    {
        "anchor": "Role of structural factors in formation of chiral magnetic soliton\n  lattice in Cr1/3NbS2: The sign and strength of magnetic interactions not only between nearest\nneighbors, but also for longer-range neighbors in the Cr1/3NbS2 intercalation\ncompound have been calculated on the basis of structural data. It has been\nfound that left-handed spin helices in Cr1/3NbS2 are formed from\nstrength-dominant at low temperatures AFM interactions between triangular\nplanes of Cr3+ ions through the plane of just one of two crystallographically\nequivalent diagonals of side faces of embedded into each other trigonal prisms\nbuilding up the crystal lattice of magnetic Cr3+ ions. These helices are\noriented along the c axis and packed into two-dimensional triangular lattices\nin planes perpendicular to these helices directions and lay one upon each other\nwith a displacement. The competition of the above AFM helices with weaker\ninter-helix AFM interactions could promote the emergence of a long-period\nhelical spin structure. One can assume that in this case the role of\nDzyaloshinskii-Moriya interaction cosists in final ordering and stabilization\nof chiral spin helices into a chiral magnetic soliton lattice. The possibility\nof emergence of solitons in M1/3NbX2 and M1/3TaX2 (M = d-elements; X = S and\nSe) intercalate compounds has been examined. Two important factors caused by\nthe crystal structure (predominantnchiral magnetic helices and their\ncompetition with weaker inter-helix interactions not destructing the system\nquasi-one-dimensional character) can be used for the crystal chemistry search\nof solitons.",
        "positive": "Exploring the structural, electronic, magnetic, and magneto-optical\n  properties of double perovskites $\\text{Ca}_2\\text{TMIrO}_6$ (TM=Fe, Co)\n  through first principles study: This study is aimed at exploring the electronic, magnetic, and\nmagneto-optical properties of double perovskites Ca$_2$FeIrO$_6$ and\nCa$_2$CoIrO$_6$ {with monoclinic structure (space group P21/$c$) } in order to\nexamine their potential applications in spintronic and photovoltaic devices.\nThe calculations were done using the full-potential linearized augmented plane\nwave within the density functional theory. For the electronic\nexchange-correlation function, we used the generalized gradient approximation\n(GGA) and GGA+U (Hubbard potential), and spin-orbit coupling (SOC). The study\nshowed that Ca$_2$FeIrO$_6$ and Ca$_2$CoIrO$_6$ exhibit a monoclinic structure\n(space group P21/$c$). The structure relaxation shows an antiferromagnetic\nbehavior in both systems with a magnetic moment of about 6.00$\\mu_B$ for\nCa$_2$FeIrO$_6$ and 4.00$\\mu_B$ for Ca$_2$CoIrO$_6$ by using GGA+U\napproximation. The results of GGA and GGA+U predict the half-metallic behavior\nof Ca$_2$FeIrO$_6$ and Ca$_2$CoIrO$_6$. The magneto-optical polar Kerr effect\n(MOKE) was examined by studying the variation of Kerr and ellipticity rotation.\nThe Kerr rotation angle is $1.3^{\\circ}$ at 4.82 eV and $-1.21^{\\circ}$ at 4.3\neV, and the ellipticity angle is $-1.21^{\\circ}$ at 4.3 eV for Ca$_2$FeIrO$_6$.\nIn the case of Ca$_2$CoIrO$_6$, the Kerr rotation angle is $-1.04^{\\circ}$ at\n4.05 eV; the significant Kerr rotation in both compounds may suggest the\napplication of these materials in optoelectronics bias. The named compounds\nhave a potential application in the field of spintronics and its devices, such\nas in optoelectronics technologies."
    },
    {
        "anchor": "Structural and Magnetic Characteristics of MnAs Nanoclusters Embedded in\n  Be-doped GaAs: We describe a systematic study of the synthesis, microstructure and\nmagnetization of hybrid ferromagnet-semiconductor nanomaterials comprised of\nMnAs nanoclusters embedded in a p-doped GaAs matrix. These samples are created\nduring the in situ annealing of Be-doped (Ga,Mn)As heterostructures grown by\nmolecular beam epitaxy. Transmission electron microscopy and magnetometry\nstudies reveal two distinct classes of nanoclustered samples whose structural\nand magnetic properties depend on the Mn content of the initial (Ga,Mn)As\nlayer. For Mn content in the range 5% - 7.5%, annealing creates a\nsuperparamagnetic material with a uniform distribution of small clusters\n(diameter around 6 nm) and with a low blocking temperature (T_B approximately\n10 K). While transmission electron microscopy cannot definitively identify the\ncomposition and crystalline phase of these small clusters, our experimental\ndata suggest that they may be comprised of either zinc-blende MnAs or Mn-rich\nregions of (Ga,Mn)As. At higher Mn content (> 8 %), we find that annealing\nresults in an inhomogeneous distribution of both small clusters as well as much\nlarger NiAs-phase MnAs clusters (diameter around 25 nm). These samples also\nexhibit supermagnetism, albeit with substantially larger magnetic moments and\ncoercive fields, and blocking temperatures well above room temperature.",
        "positive": "Uncovering the (un-)occupied electronic structure of a buried hybrid\n  interface: The energy level alignment at organic/inorganic (o/i) semiconductor\ninterfaces is crucial for any light-emitting or -harvesting functionality.\nEssential is the access to both occupied and unoccupied electronic states\ndirectly at the interface, which is often deeply buried underneath thick\norganic films and challenging to characterize. We use several complementary\nexperimental techniques to determine the electronic structure of\np-quinquephenyl pyridine (5P-Py) adsorbed on ZnO(10-10). The parent anchoring\ngroup, pyridine, significantly lowers the work function by up to 2.9 eV and\ncauses an occupied in-gap state (IGS) directly below the Fermi level\n$E_\\text{F}$. Adsorption of upright-standing 5P-Py also leads to a strong work\nfunction reduction of up to 2.1 eV and to a similar IGS. The latter is then\nused as an initial state for the transient population of three normally\nunoccupied molecular levels through optical excitation and, due to its\nlocalization right at the o/i interface, provides interfacial sensitivity, even\nfor thick 5P-Py films. We observe two final states above the vacuum level and\none bound state at around 2 eV above $E_\\text{F}$, which we attribute to the\n5P-Py LUMO. By the separate study of anchoring group and organic dye combined\nwith the exploitation of the occupied IGS for selective interfacial\nphotoexcitation this work provides a new pathway for characterizing the\nelectronic structure at buried o/i interfaces."
    },
    {
        "anchor": "Lamellae Stability in Confined Systems with Gravity: The microphase separation of a diblock copolymer melt confined by hard walls\nand in the presence of a gravitational field is simulated by means of a cell\ndynamical system model. It is found that the presence of hard walls normal to\nthe gravitational field are key ingredients to the formation of well ordered\nlamellae in BCP melts. To this effect the currents in the directions normal and\nparallel to the field are calculated along the interface of a lamellar domain,\nshowing that the formation of lamellae parallel to the hard boundaries and\nnormal to the field correspond to the stable configuration. Also, it is found\nthet the field increases the interface width.",
        "positive": "Thermal Expansion Coefficient and Phonon Dynamics in Coexisting\n  Allotropes of Monolayer WS2 Probed by Raman Scattering: We report a comprehensive temperature dependent Raman measurements on three\ndifferent phases of monolayer WS2 from 4K to 330K in a wide spectral range. Our\nstudies revels the anomalous nature of the first as well as the higher order\ncombination modes reflected in the disappearance of the few modes and anomalous\ntemperature evaluation of the phonon self-energy parameters attributed to the\ndetuning of resonance condition and development of strain due to thermal\nexpansion mismatch with the underlying substrate. Our detailed temperature\ndependence studies also decipher the ambiguity about assignment of the two\nmodes in literature near ~ 297 cm-1 and 325 cm-1. Mode near 297 cm-1 is\nassigned as first order Raman mode, which is forbidden in the backscattering\ngeometry and 325 cm-1 is assigned to the combination of and mode. We also\nestimated thermal expansion coefficient by systematically disentangling the\nsubstrate effect in the temperature range of 4K to 330K and probed its\ntemperature dependence in 1H, 1T and 1T' phases."
    },
    {
        "anchor": "Structural, hydrogen bonding and dipolar properties of alkyl\n  imidazolium-based ionic liquids: a classical and first-principles molecular\n  dynamics study: Ionic liquids (ILs) feature a tailorable and wide range of structural,\nchemical and electronic properties that make this class of materials suitable\nto a broad variety of forefront applications in next-generation electronics.\nYet, their intrinsic complexity call for special attention and experimental\nprobes have still limitations in unraveling the interactions occurring both in\nthe bulk IL and at the interface with the solid substrates used to build the\ndevices. This works provides an atomistic insight into these fundamental\ninteractions by molecular modeling to complement the information still not\naccessible to experiments. In particular, we shed some light on the nature of\nthe chemical bonding, structure, charge distribution and dipolar properties of\na series of alkyl-imidazolium-based ILs by a synergy of classical and\nfirst-principles molecular dynamics simulations. Special emphasis is given to\nthe crucial issue of the hydrogen bond network formation ability depending\neither on the nature of the anion or on the length of the alkyl chain of the\ncation. The hydrogen bond strength is a fundamental indicator of the cohesive\nand ordering features of the ILs and, in this respect, might be exploited to\nfoster a different behaviour of the IL used a bulk medium or when used in\nelectronic devices.",
        "positive": "Phase Boundary Exchange Coupling in the Mixed Magnetic Phase Regime of a\n  Pd-doped FeRh Epilayer: Spin-wave resonance measurements were performed in the mixed magnetic phase\nregime of a Pd-doped FeRh epilayer that appears as the first-order\nferromagnetic-antiferromagnetic phase transition takes place. It is seen that\nthe measured value of the exchange stiffness is suppressed throughout the\nmeasurement range when compared to the expected value of the fully\nferromagnetic regime, extracted via the independent means of a measurement of\nthe Curie point, for only slight changes in the ferromagnetic volume fraction.\nThis behavior is attributed to the influence of the antiferromagnetic phase:\ninspired by previous experiments that show ferromagnetism to be most persistent\nat the surfaces and interfaces of FeRh thin films, we modelled the\nantiferromagnetic phase as forming a thin layer in the middle of the epilayer\nthrough which the two ferromagnetic layers are coupled up to a certain critical\nthickness. The development of this exchange stiffness is then consistent with\nthat expected from the development of an exchange coupling across the magnetic\nphase boundary, as a consequence of a thickness dependent phase transition\ntaking place in the antiferromagnetic regions and is supported by complimentary\ncomputer simulations of atomistic spin-dynamics. The development of the Gilbert\ndamping parameter extracted from the ferromagnetic resonance investigations is\nconsistent with this picture."
    },
    {
        "anchor": "Anomalous organic magnetoresistance from competing\n  carrier-spin-dependent interactions with localized electronic and nuclear\n  spins: We describe a new regime for low-field magnetoresistance in organic\nsemiconductors, in which the spin-relaxing effects of localized nuclear spins\nand electronic spins interfere. The regime is studied by the controlled\naddition of localized electronic spins to a material that exhibits substantial\nroom-temperature magnetoresistance ($\\sim 20$\\%). Although initially the\nmagnetoresistance is suppressed by the doping, at intermediate doping there is\na regime where the magnetoresistance is insensitive to the doping level. For\nmuch greater doping concentrations the magnetoresistance is fully suppressed.\nThe behavior is described within a theoretical model describing the effect of\ncarrier spin dynamics on the current.",
        "positive": "Impact of elasticity on the piezoresponse of adjacent ferroelectric\n  domains investigated by scanning force microscopy: As a consequence of elasticity, mechanical deformations of crystals occur on\na length scale comparable to their thickness. This is exemplified by applying a\nhomogeneous electric field to a multi-domain ferroelectric crystal: as one\ndomain is expanding the adjacent ones are contracting, leading to clamping at\nthe domain boundaries. The piezomechanically driven surface corrugation of\nmicron-sized domain patterns in thick crystals using large-area top electrodes\nis thus drastically suppressed, barely accessible by means of piezoresponse\nforce microscopy."
    },
    {
        "anchor": "All hourglass bosonic excitations in the 1651 magnetic space groups and\n  528 magnetic layer groups: The band connectivity as imposed by the compatibility relations between the\nirreducible representations of little groups can give rise to the exotic\nhourglass-like shape composed of four branches of bands and five band crossings\n(BCs). Such an hourglass band connectivity could enforce the emergence of\nnontrivial excitations like Weyl fermion, Dirac fermion or even beyond them. On\nthe other hand, the bosons, like phonons, magnons, and photons, were also shown\nto possess nontrivial topology and a comprehensive symmetry classification of\nthe hourglass bosonic excitations would be of great significance to both\nmaterials design and device applications. Here we firstly list all concrete\npositions and representations of little groups in the Brillouin zone (BZ)\nrelated with the hourglass bosonic excitations in all the 1651 magnetic space\ngroups and 528 magnetic layer groups, applicable to three dimensional (3D) and\ntwo dimensional (2D) systems, respectively. 255 (42) MSGs (MLGs) are found to\nessentially host such hourglass BCs: Here ``essentially'' means that the\nbosonic hourglass BC exists definitely as long as the studied system is\ncrystallized in the corresponding MSG/MLG. We also perform first-principles\ncalculations on hundreds of 3D nonmagnetic materials essentially hosting\nhourglass phonons and propose that the 2D material AlI can host hourglass\nphonons. We choose AuX (X=Br and I) as illustrative examples to demonstrate\nthat two essential hourglass band structures can coexist in the phonon spectra\nfor both materials while for AuBr, an accidental band crossing sticking two\nhourglasses is found interestingly. Our results of symmetry conditions for\nhourglass bosonic excitations can provide a useful guide of designing\nartificial structures with hourglass bosonic excitations.",
        "positive": "Mn-doped Ga(As,P) and (Al,Ga)As ferromagnetic semiconductors: A remarkable progress towards functional ferromagnetic semiconductor\nmaterials for spintronics has been achieved in p-type (Ga,Mn)As. Robust\nhole-mediated ferromagnetism has, however, been observed also in other III-V\nhosts such as antimonides, GaP or (Al,Ga)As which opens a wide area of\npossibilities for optimizing the host composition towards higher ferromagnetic\nCurie temperatures. Here we explore theoretically ferromagnetism and Mn\nincorporation in Ga(As,P) and (Al,Ga)As ternary hosts. While alloying (Ga,Mn)As\nwith Al has only a small effect on the Curie temperature we predict a sizable\nenhancement of Curie temperatures in the smaller lattice constant Ga(As,P)\nhosts. Mn-doped Ga(As,P) is also favorable, as compared to (Al,Ga)As, with\nrespect to the formation of carrier and moment compensating interstitial Mn\nimpurities. In (Ga,Mn)(As,P) we find a marked decrease of the partial\nconcentration of these detrimental impurities with increasing P content."
    },
    {
        "anchor": "Designing 3D topological insulators by 2D-Xene (X = Ge, Sn) sheet\n  functionalization in the GaGeTe-type structures: State-of-the-art theoretical studies anticipate a 2D Dirac system in the\n\"heavy\" analogues of graphene, free-standing buckled honeycomb-like Xenes (X =\nSi, Ge, Sn, Pb, etc.). Herewith a structurally and electronically resembling 2D\nsheet, which can be regarded as Xene functionalized by covalent interactions\nwithin a 3D periodic structure, is predicted to constitute a 3D strong\ntopological insulator with Z2 = 1;(111) (primitive cell, rhombohedral setting)\nin the structural family of layered AXTe (A = Ga, In; X = Ge, Sn) bulk\nmaterials. The host structure GaGeTe is a long-known bulk semiconductor; the\n\"heavy\", isostructural analogues InSnTe and GaSnTe are predicted to be\ndynamically stable. Spin-orbit interaction in InSnTe opens a small topological\nband gap with inverted gap edges that are mainly composed of the In-5s and\nTe-5p states. Our simulations classify GaSnTe as a semimetal with topological\nproperties, whereas the verdict for GaGeTe is not conclusive and urges further\nexperimental verification. AXTe family structures can be regarded as stacks of\n2D layered cut-outs from a zincblende-type lattice and are composed by elements\nthat are broadly used in modern semiconductor devices; hence they represent an\naccessible, attractive alternative for applications in spintronics. The layered\nnature of AXTe should facilitate exfoliation of its hextuple layers and\nmanufacture of heterostuctures.",
        "positive": "A note on the dynamics and thermodynamics of dislocated crystals: The dynamics and thermodynamics of dislocated crystals are studied within the\nframework of the nonlinear theory of elastic and plastic deformations."
    },
    {
        "anchor": "Phase field simulation of grain size effects in nanograined Ti-Nb shape\n  memory alloys: Titanium-based shape memory alloys, such as Ti2448, have attracted enormous\nattention owing to their unique thermomechanical properties and potential\nbiomedical applications. In this study, we develop a polycrystalline phase\nfield to investigate the grain size dependence of the martensitic\ntransformation and associated mechanical properties of nanograined Ti-Nb\nalloys. It is shown that a reduction of the average grain size strengthens the\nsuppression of the martensitic transformation (MT), leading to an increase of\nthe transformation stress, shrinkage of the stress hysteresis, and elimination\nof residual strain. The time-temperature-transformation curves of nano-grained\nTi-Nb alloys with different average grain sizes are obtained and the validity\nof Hall-Petch relation is also confirmed in all studied grain sizes.\nFurthermore, when the average grain size becomes ultrasmall, both the\ntemperature- and stress-induced MTs show the continuous second-order phase\ntransition behavior. These superior transformation characteristics are\nattributed to the high density of grain boundaries and the related dominant\nrole of the gradient energy at the nanoscale. Our results have profound\nimplications for the design and control of the properties in nano-grained shape\nmemory alloys.",
        "positive": "Growth of Pure and Intercalated ZrTe2, TiTe2 and HfTe2 Dichalcogenide\n  Single Crystals by Isothermal Chemical Vapor Transport: We report on a modified chemical vapor transport (CVT) methodology for the\ngrowth of pure and intercalated Zr, Ti, and Hf dichalcogenide single crystals,\ne.g. ZrTe2, Gd0.05ZrTe2, HfTe2, and Cu0.05TiTe2. While the most common method\nfor CVT growth is carried out in quartz tubes subjected to a temperature\ngradient between the charge and the growth location, the growth using this\nisothermal-CVT (ICVT) method takes place isothermally in sealed quartz tubes\nplaced horizontally in box furnaces, using iodine (I2) as the transport agent.\nThe structure and composition of crystals were determined by means of X-ray\ndiffraction (XRD), scanning electron microscopy (SEM), and induced coupling\nplasma (ICP). The crystals grown with this method can be large, and show\nexcellent crystallinity and homogeneity. Their morphology is plate-like, and\nthe larger dimensions can be as long as 15 mm."
    },
    {
        "anchor": "Adaptive Genetic Algorithm for Crystal Structure Prediction: We present a genetic algorithm (GA) for structural search that combines the\nspeed of structure exploration by classical potentials with the accuracy of\ndensity functional theory (DFT) calculations in an adaptive and iterative way.\nThis strategy increases the efficiency of the DFT-based GA by several orders of\nmagnitude. This gain allows considerable increase in size and complexity of\nsystems that can be studied by first principles. The method's performance is\nillustrated by successful structure identifications of complex binary and\nternary inter-metallic compounds with 36 and 54 atoms per cell, respectively.\nThe discovery of a multi-TPa Mg-silicate phase with unit cell containing up to\n56 atoms is also reported. Such phase is likely to be an essential component of\nterrestrial exoplanetary mantles.",
        "positive": "Selective Heating Mechanism of Magnetic Metal Oxides by Alternating\n  Magnetic Field in Microwave Sintering Process: The mechanism of rapid and selective heating of magnetic metal oxides under\nthe magnetic field of microwaves which continues beyond the Curie temperature $\nT_{c} $ is identified by using the Heisenberg model. Monte Carlo calculations\nbased on the energy principle show that such heating is caused by non-resonant\nresponse of electron spins in the unfilled 3d shell to the wave magnetic field.\nSmall spin reorientation thus generated leads to a large internal energy change\nthrough the exchange interactions between spins, which becomes maximal around $\nT_{c} $ for magnetite $ {\\rm Fe}_{3}{\\rm O}_{4} $. The dissipative spin\ndynamics simulation yields the imaginary part of the magnetic susceptibility,\nwhich becomes largest around $ T_{c} $ and for the microwave frequency around 2\nGHz. Hematite $ {\\rm Fe}_{2}{\\rm O}_{3} $ with weak spontaneous magnetization\nresponds much less to microwaves as observed in experiments. The heating of\ntitanium oxide by microwave magnetic field only when oxygen defects are present\nis also explained by our theory in terms of the absence of spontaneous\nmagnetization."
    },
    {
        "anchor": "Magnetic structure and ferroelectric activity in orthorhombic YMnO3:\n  relative roles of magnetic symmetry breaking and atomic displacements: We discuss relative roles played by the magnetic inversion symmetry breaking\nand the ferroelectric (FE) atomic displacements in the multiferroic state of\nYMnO3. For these purposes we derive a realistic low-energy model, using results\nof first-principles calculations and experimental parameters of the crystal\nstructure. Then, we solve this model in the Hartree-Fock approximation. We\nargue that the multiferroic state in YMnO3 has a magnetic origin, and the\ncentrosymmetric Pbnm structure is formally sufficient for explaining details of\nthe noncentrosymmetric magnetic ground state. The relativistic spin-orbit\ninteraction lifts the degeneracy, caused by the frustration of isotropic\ninteractions, and stabilizes a twofold periodic magnetic state, which is\nsimilar to the E-state apart from the spin canting. The noncentrosymmetric\natomic displacements in the P2_1nm phase reduce the spin canting, but do not\nchange the symmetry of the magnetic state. The effect of the P2_1nm distortion\non the FE polarization P_a is twofold: (i) it gives rise to ionic\ncontributions, associated with the Y and O sites; (ii) it affects the\nelectronic polarization, through the change of the spin canting. The relatively\nsmall value of P_a, observed in the experiment, is caused by a partial\ncancelation of the electronic and ionic contributions in the experimental\nP2_1nm structure. Finally, we theoretically optimize the crystal structure, by\nusing the LSDA+U approach and assuming the collinear E-type alignment. We have\nfound that the agreement with the experimental data in this case is less\nsatisfactory and P_a is largely overestimated. Although the magnetic structure\ncan be formally tuned by varying the Coulomb repulsion U as a parameter,\napparently LSDA+U fails to reproduce some fine details of the experimental\nstructure, and the cancelation of different contributions in P_a does not\noccur.",
        "positive": "Experimental study of the Fluctuation-Dissipation-Relation during an\n  aging process: The validity of fluctuation dissipation relations in an aging system is\nstudied in a colloidal glass during the transition from a fluid-like to a\nsolid-like state. The evolution of the rheological and electrical properties is\nanalyzed in the range $1Hz - 40Hz$. It is found that at the beginning of the\ntransition the fluctuation dissipation relation is strongly violated in\nelectrical measurements. The amplitude and the persistence time of this\nviolation are decreasing functions of frequency. At the lowest frequencies of\nthe measuring range it persists for times which are about 5% of the time needed\nto form the colloidal glass. This phenomenology is quite close to the recent\ntheoretical predictions done for the violation of the fluctuation dissipation\nrelation in glassy systems. In contrast in the rheological measurements no\nviolation of the fluctuation dissipation relation is observed. The reasons of\nthis large difference between the electrical and rheological measurements are\ndiscussed."
    },
    {
        "anchor": "Orientation Controlled Anisotropy in Single Crystals of Quasi-1D BaTiS3: Low-dimensional materials with chain-like (one-dimensional) or layered\n(twodimensional) structures are of significant interest due to their\nanisotropic electrical, optical, thermal properties. One material with\nchain-like structure, BaTiS3 (BTS), was recently shown to possess giant\nin-plane optical anisotropy and glass-like thermal conductivity. To understand\nthe origin of these effects, it is necessary to fully characterize the optical,\nthermal, and electronic anisotropy of BTS. To this end, BTS crystals with\ndifferent orientations (aand c-axis orientations) were grown by chemical vapor\ntransport. X-ray absorption spectroscopy (XAS) was used to characterize the\nlocal structure and electronic anisotropy of BTS. Fourier transform infrared\n(FTIR) reflection/transmission spectra show a large inplane optical anisotropy\nin the a-oriented crystals, while the c-axis oriented crystals were nearly\nisotropic in-plane. BTS platelet crystals are promising uniaxial materials for\nIR optics with their optic axis parallel to the c-axis. The thermal\nconductivity measurements revealed a thermal anisotropy of ~4.5 between the c-\nand a-axis. Time-domain Brillouin scattering showed that the longitudinal sound\nspeed along the two axes is nearly the same suggesting that the thermal\nanisotropy is a result of different phonon scattering rates.",
        "positive": "Optical response of a nematic liquid crystal cell at splay-bend\n  transition: model and dynamic simulation: We study dynamical optical response of a nematic liquid crystal cell that\nundergoes the splay-bend transition after applying the voltage across the cell.\nWe formulate a simplified model that takes into account both the flexoelectric\ncoupling and the surface rotational viscosity. The dynamic equations of the\nmodel were solved numerically to calculate temporal evolution of the director\nprofile and the transmittance. We evaluate the response time as a function of a\nnumber of parameters characterising dielectric and elastic anisotropies,\nasymmetry of the surface pretilt angles, anchoring energy, surface rotational\nviscosity and flexoelectricity."
    },
    {
        "anchor": "Diffuse wave density and directionality in anisotropic solids: Several general results are derived for diffuse waves in anisotropic solids,\nincluding concise expressions for the modal density per unit volume and for the\nparticipation factor matrix G. The latter is a second order tensor which\ndescribes the orientational distribution of diffuse wave or reverberant energy,\nand reduces to the identity I under isotropy. Calculations of G for a variety\nof example materials show significant deviation from I even under moderate\nlevels of anisotropy.",
        "positive": "Exciton energy transfer in nanotube bundles: Photoluminescence is commonly used to identify the electronic structure of\nindividual nanotubes. But, nanotubes naturally occur in bundles. Thus, we\ninvestigate photoluminescence of nanotube bundles. We show that their complex\nspectra are simply explained by exciton energy transfer between adjacent tubes,\nwhereby excitation of large gap tubes induces emission from smaller gap ones\nvia Forster interaction between excitons. The consequent relaxation rate is\nfaster than non-radiative recombination, leading to enhanced photoluminescence\nof acceptor tubes. This fingerprints bundles with different compositions and\nopens opportunities to optimize them for opto-electronics."
    },
    {
        "anchor": "An experimental and theoretical study of Ni impurity centers in\n  Ba$_{0.8}$Sr$_{0.2}$TiO$_3$: The local environment and the charge state of a nickel impurity in cubic\nBa$_{0.8}$Sr$_{0.2}$TiO$_3$ are studied by XAFS spectroscopy. According to the\nXANES data, the mean Ni charge state is $\\sim$2.5+. An analysis of the EXAFS\nspectra and their comparison with the results of first-principle calculations\nof the defect geometry suggest that Ni$^{2+}$ ions are in a high-spin state at\nthe $B$ sites of the perovskite structure and the difference of the Ni$^{2+}$\nand Ti$^{4+}$ charges is mainly compensated by distant oxygen vacancies. In\naddition, a considerable amount of nickel in the sample is in a second phase\nBaNiO$_{3-\\delta}$. The measurements of the lattice parameter show a decrease\nin the unit cell volume upon doping, which can indicate the existence of a\nsmall amount of Ni$^{4+}$ ions at the $B$ sites.",
        "positive": "Freezing of Simple Liquid Metals: Freezing of simple liquid metals and the relative stabilities of competing\ncrystalline solids are investigated using thermodynamic perturbation theory,\nthe interactions between ions being modeled by effective pair potentials\nderived from pseudopotential theory. The ionic free energy of the solid phase\nis calculated, to first order in the perturbation potential, using classical\ndensity-functional theory and an accurate approximation to the hard-sphere\nradial distribution function. Free energy calculations for Na, Mg, and Al yield\nwell-defined freezing transitions and structural free energy differences for\nbcc, fcc, and hcp crystals in qualitative agreement with experiment."
    },
    {
        "anchor": "Simulation of Growth of Graded Bandgap Solid Solutions of GaAsxP1-x at\n  Liquid Phase Electroepitaxy: The possibility of the composition control of the GaAs1-xPx solid solution on\nthe GaAs substrate at liquid phase electroepitaxy from the Ga-As-P\nsolution-melt is theoretically considered. By the simulation it was determined,\nthat under steady-state conditions specifying such parameters of the process as\nthe temperature and/or the thickness of the growth space it is possible to\nobtain graded bandgap layers of the GaAs1-xPx solid solution with increasing of\nthe content of P towards the surface of the layer that possess the composition\ngradient from 0.5x10-4 mole fraction/nm to 2.0x10-3 mole fraction/nm. It was\nalso shown that control of the composition of ternary solid solutions at liquid\nphase electroepitaxy can be realized by use of unsteady state electric field.",
        "positive": "Electron-Phonon Coupling and Thermal Conductance at a\n  Metal-Semiconductor Interface: First-principles Analysis: The mechanism of heat transfer and the contribution of electron-phonon\ncoupling to thermal conductance of a metal-semiconductor interface remains\nunclear in the present literature. We report ab initio simulations of a\ntechnologically important titanium silicide (metal) - silicon (semiconductor)\ninterface to estimate the Schottky barrier height (SBH), and the strength of\nelectron-phonon and phonon-phonon heat transfer across the interface. The\nelectron and phonon dispersion relations of TiSi$_2$ with C49 structure and the\nTiSi$_2$-Si interface are obtained using first-principles calculations within\nthe density functional theory (DFT) framework. These are used to estimate\nelectron-phonon linewidths and the associated Eliashberg function that\nquantifies coupling. We show that the coupling strength of electrons with\ninterfacial phonon modes is of the same order of magnitude as coupling of\nelectrons to phonon modes in the bulk metal, and its contribution to\nelectron-phonon interfacial conductance is comparable to the harmonic\nphonon-phonon conductance across the interface."
    },
    {
        "anchor": "Using small-angle scattering to guide functional magnetic nanoparticle\n  design: Magnetic nanoparticles offer unique potential for various technological,\nbiomedical, or environmental applications thanks to the size-, shape- and\nmaterial-dependent tunability of their magnetic properties. To optimize\nparticles for a specific application, it is crucial to interrelate their\nperformance with their structural and magnetic properties. This review presents\nthe advantages of small-angle X-ray and neutron scattering techniques for\nachieving a detailed multiscale characterization of magnetic nanoparticles and\ntheir ensembles in a mesoscopic size range from 1 to a few hundred nanometers\nwith nanometer resolution. Both X-rays and neutrons allow the ensemble-averaged\ndetermination of structural properties, such as particle morphology or particle\narrangement in multilayers and 3D assemblies. Additionally, the magnetic\nscattering contributions enable retrieving the internal magnetization profile\nof the nanoparticles as well as the inter-particle moment correlations caused\nby interactions within dense assemblies. Most measurements are used to\ndetermine the time-averaged ensemble properties, in addition advanced\nsmall-angle scattering techniques exist that allow accessing particle and spin\ndynamics on various timescales. In this review, we focus on conventional\nsmall-angle X-ray and neutron scattering (SAXS and SANS), X-ray and neutron\nreflectometry, gracing-incidence SAXS and SANS, X-ray resonant magnetic\nscattering, and neutron spin-echo spectroscopy techniques. For each technique,\nwe provide a general overview, present the latest scientific results, and\ndiscuss its strengths as well as sample requirements. Finally, we give our\nperspectives on how future small-angle scattering experiments, especially in\ncombination with micromagnetic simulations, could help to optimize the\nperformance of magnetic nanoparticles for specific applications.",
        "positive": "Band-unfolding approach to Moir\u00e8-induced band-gap opening and\n  Fermi-level-velocity reduction in twisted bilayer graphene: We report on the energy spectrum of electrons in twisted bilayer graphene\n(tBLG) obtained by the band-unfolding method in the tight-binding model. We\nfind the band-gap opening at particular points in the reciprocal space, that\nelucidates the drastic reduction of the Fermi-level velocity with the tiny\ntwisted angles in tBLGs. We find that Moir\\`e pattern caused by the twist of\nthe two graphene layers generates interactions among Dirac cones, otherwise\nabsent, and the resultant cone-cone interactions peculiar to each point in the\nreciprocal space causes the energy gap and thus reduced the Fermi-level\nvelocity."
    },
    {
        "anchor": "Plasticity and Dislocation Dynamics in a Phase Field Crystal Model: The critical dynamics of dislocation avalanches in plastic flow is examined\nusing a phase field crystal (PFC) model. In the model, dislocations are\nnaturally created, without any \\textit{ad hoc} creation rules, by applying a\nshearing force to the perfectly periodic ground state. These dislocations\ndiffuse, interact and annihilate with one another, forming avalanche events. By\ndata collapsing the event energy probability density function for different\nshearing rates, a connection to interface depinning dynamics is confirmed. The\nrelevant critical exponents agree with mean field theory predictions.",
        "positive": "Surface control of flexoelectricity: The polarization response of a material to a strain gradient, known as\nflexoelectricity, holds great promise for novel electromechanical applications.\nDespite considerable recent progress, however, the effect remains poorly\nunderstood. From both the fundamental and practical viewpoints, it is of\ncrucial importance to know whether the coupling coefficients are primarily\ngoverned by the properties of the bulk material or by the details of the sample\nsurface. Here we provide, by means of first-principles calculations,\nquantitative evidence supporting the latter scenario. In particular, we\ndemonstrate that a SrTiO$_3$ film can yield a positive or negative\nflexoelectric voltage depending on its surface termination. This result points\nto a full control of the flexoelectric effect via surface/interface\nengineering, opening exciting new avenues for device design."
    },
    {
        "anchor": "Magnetotransport properties of the topological nodal-line semimetal\n  CaCdSn: Topological nodal-line semimetals support protected band crossings which form\nnodal lines or nodal loops between the valence and conduction bands and exhibit\nnovel transport phenomena. Here we address the topological state of the\nnodal-line semimetal candidate material, CaCdSn, and report magnetotransport\nproperties of its single crystals grown by the self-flux method. Our\nfirst-principles calculations show that the electronic structure of CaCdSn\nharbors a single nodal loop around the $\\Gamma$ point in the absence of\nspin-orbit coupling (SOC) effects. The nodal crossings in CaCdSn are found to\nlie above the Fermi level and yield a Fermi surface that consists of both\nelectron and hole pockets. CaCdSn exhibits high mobility ($\\mu \\approx\n3.44\\times 10^4$ cm$^2$V$^{-1}$s$^{-1}$) and displays a field-induced\nmetal-semiconductor like crossover with a plateau in resistivity at low\ntemperature. We observe an extremely large and quasilinear non-saturating\ntransverse as well as longitudinal magnetoresistance (MR) at low temperatures\n($\\approx 7.44\\times 10^3 \\%$ and $\\approx 1.71\\times 10^3\\%$, respectively, at\n4K). We also briefly discuss possible reasons behind such a large quasilinear\nmagnetoresistance and its connection with the nontrivial band structure of\nCaCdSn.",
        "positive": "Multi-layer Ti-based Coating Obtained by Arc PVD Method: We report the obtaining and primary studies of ~ 250microns thick multi-layer\nTi-based protective coating deposited at high cooling rate from substance\ngenerated by cathode arc discharge in vacuum. High adhesion to steel substrate\nwas attained through prior Arc plasma generator cleaning and successive Ion\nBombardment method. All three arc-generated fractions including mainly droplet,\nvapour and ions have been utilised to form the coating. Obtained coating\nfeatures pore-free, least defects and high hardness which, besides N presence,\nsupposed to result from mainly martensitic transformations occurred at the\npresence of Nitrogen. Two intermediate thin layers of Cu of few microns were\nachieved to insert within coating presumably to reduce overall elastic modulus\nof the material."
    },
    {
        "anchor": "Spin Hall effect by surface roughness: The spin Hall effect and its inverse effect, caused by the spin orbit\ninteraction, provide the interconversion between spin current and charge\ncurrent. Since the effects make it possible to generate and manipulate spin\ncurrent electrically, how to realize the large effects is an important issue in\nboth physics and applications. To do so, materials with heavy elements, which\nhave strong spin orbit interaction, have been examined so far. Here, we propose\na new mechanism to enhance the spin Hall effect without heavy elements, \\ie\nsurface roughness in metallic thin films. We examine Cu and Al thin films with\nsurface roughness and find that they give the spin Hall effect comparable to\nthat in bulk Au. We demonstrate that the spin Hall effect induced by surface\nroughness has the side jump contribution but not skew scattering.",
        "positive": "High elasticity and strength of ultra-thin metallic transition metal\n  dichalcogenides: Mechanical properties of transition metal dichalcogenides (TMDCs) are\nrelevant to their prospective applications in flexible electronics. So far, the\nfocus has been on the semiconducting TMDCs, mostly MoX2 and WX2 (X=S, Se) due\nto their potential in optoelectronics. A comprehensive understanding of the\nelastic properties of metallic TMDCs is needed to complement the semiconducting\nTMDCs in flexible optoelectronics. Thus, mechanical testing of metallic TMDCs\nis pertinent to the realization of the applications. Here, we report on the\natomic force microscopy-based nano-indentation measurements on ultra-thin\n2H-TaS2 crystals to elucidate the stretching and breaking of the metallic\nTMDCs. We explored the elastic properties of 2H-TaS2 at different thicknesses\nranging from 3.5 nm to 12.6 nm and find that the Young's modulus is independent\nof the thickness at a value of 85.9 +- 10.6 GPa, which is lower than the\nsemiconducting TMDCs reported so far. We determined the breaking strength as\n5.07 4- 0.10 GPa which is 6% of the Young's modulus. This value is comparable\nto that of other TMDCs. We used ab initio calculations to provide an insight to\nthe high elasticity measured in 2H-TaS2. We also performed measurements on a\nsmall number of 1T-TaTe2, 3R-NbS2 and 1T-NbTe2 samples and extended our ab\ninitio calculations to these materials to gain a deeper understanding on the\nelastic and breaking properties of metallic TMDCs. This work illustrates that\nthe studied metallic TMDCs are suitable candidates to be used as additives in\ncomposites as functional and structural elements and for flexible conductive\nelectronic devices."
    },
    {
        "anchor": "Inelastic lifetimes of hot electrons in real metals: We report a first-principles description of inelastic lifetimes of excited\nelectrons in real Cu and Al, which we compute, within the GW approximation of\nmany-body theory, from the knowledge of the self-energy of the excited\nquasiparticle. Our full band-structure calculations indicate that actual\nlifetimes are the result of a delicate balance between localization, density of\nstates, screening, and Fermi-surface topology. A major contribution from\n$d$-electrons participating in the screening of electron-electron interactions\nyields lifetimes of excited electrons in copper that are larger than those of\nelectrons in a free-electron gas with the electron density equal to that of\nvalence ($4s^1$) electrons. In aluminum, a simple metal with no $d$-bands,\nsplitting of the band structure over the Fermi level results in electron\nlifetimes that are smaller than those of electrons in a free-electron gas.",
        "positive": "Electric field manipulation enhanced by strong spin-orbit coupling:\n  promoting rare-earth ions as qubits: Quantum information processing based on magnetic ions are considered\npotential candidates for applications because they can be modified and scaled\nup by a variety of chemical methods. For these systems to achieve individual\nspin addressability and high energy efficiency, we exploited the electric field\nas a tool to manipulate their quantum behaviours, functioning via spin-orbit\ncoupling. A Ce:YAG single crystal was employed due to that rare-earth ions have\nstrong spin-orbit coupling and with considerations regarding the dynamics and\nthe symmetry requirements. The Stark effect of the Ce3+ ion was observed and\nmeasured. When demonstrated as a quantum phase gate, the electric field\nmanipulation exhibited high efficiency which allowed up to 57 {\\pi}/2\noperations before decoherence with optimized field directions. It was also\nutilized to carry out quantum bang-bang control, as a method of dynamic\ndecoupling, and the refined Deutsch-Jozsa algorithm. Our experiments\nhighlighted rare-earth ions as potentially applicable qubits since they offer\nenhanced spin-electric coupling which enables high-efficiency quantum\nmanipulation."
    },
    {
        "anchor": "Current-modulation annealing to control microwave permittivity in\n  composites with melt-extracted microwires: We investigate the microwave properties of epoxy-based composite containing\nmelt-extracted CoFeBSiNb microwires fabricated by a combined current-modulation\nannealing (CCMA) technique. We observe a shift of the resonance peak in the\neffective permittivity spectra of the composite sample containing annealed 25\nmm Nb-doped microwires as an applied magnetic field is increased. This\nobservation is consistent with the absorption-dominated impedance for thick\nmicrowires and the ferromagnetic resonance phenomenon. It is shown that CCMA is\nan appropriate technique to release internal residual stresses. Hence, for\nsamples containing small amounts of Nb, we observe that CCMA allows us to\nsuppress the high frequency resonance peak observed in samples containing\nas-cast wires. However, for samples containing a high amount of Nb, the high\nfrequency peak remains despite the CCMA treatment. In this case, the\nobservation of a two-peak feature in the permittivity spectra is attributed to\nthe coexistence of the amorphous phase and a small amount of nanocrystallites\ndistributed at the wire surface. However, due to large magnetostatic energy of\nlong (35 mm) and short (15 mm) as-cast wires and imperfect wire-epoxy bonding\nno shift of the resonance peak and the characteristic double peak of the\npermittivity spectrum can be detected. Overall, CCMA emerges as a promising\nstrategy to control microwave permittivity in composites with melt-extracted\nmicrowires.",
        "positive": "Probing the Electrical Properties of Overlapped Graphene Grain\n  Boundaries by Raman spectroscopy: The effect of grain boundaries and wrinkles on the electrical properties of\npolycrystalline graphene is pronounced. Here we investigate the stitching\nbetween grains of polycrystalline graphene, specifically, overlapping of layers\nat the boundaries, grown by chemical vapor deposition (CVD) and subsequently\ndoped by the oxidized Cu substrate. We analyze overlapped regions between 60\nand 220 nm wide via Raman spectroscopy, and find that some of these overlapped\nboundaries contain AB stacked bilayers. The Raman spectra from the overlapped\ngrain boundaries are distinctly different from bilayer graphene and exhibit\nsplitting of the G band peak. The degree of splitting, peak widths, as well as\npeak intensities depend on the width of the overlap. We attribute these\nfeatures to inhomogeneous doping by charge carriers (holes) across the\noverlapped regions via the oxidized Cu substrate. As a result, the Fermi level\nat the overlapped grain boundaries lies between 0.3 and 0.4 eV below the charge\nneutrality point. Our results suggest an enhancement of electrical conductivity\nacross overlapped grain boundaries, similar to previously observed\nmeasurements(1). The dependence of charge distribution on the width of\noverlapping of grain boundaries may have strong implications for the growth of\nlarge-area graphene with enhanced conductivity."
    },
    {
        "anchor": "Hybrid Perovskites, Metal--Organic Frameworks, and Beyond:\n  Unconventional Degrees of Freedom in Molecular Frameworks: The structural degrees of freedom of a material are the various distortions\nmost straightforwardly activated by external stimuli. A highly successful\ndesign strategy in materials chemistry involves controlling these individual\ndistortions to produce useful functional responses. In a ferroelectric such as\nlead titanate, for example, the key degree of freedom involves displacements of\nPb$^{2+}$; by coupling these together, the system interacts with electric\nfields. An exciting development has been to exploit the interplay between\ndifferent distortions: $e.g.$ generating polarisation by combining different\npolyhedral rotations. Thus, degrees of freedom act as geometric `elements' that\ncan be combined to engineer materials with interesting properties. Just as the\ndiscovery of new elements diversified chemical space, identifying new types of\nstructural degrees of freedom is a key strategy for developing new functional\nmaterials. In this context, molecular frameworks are a fertile source of\nunanticipated distortion types, many of which have no parallel in conventional\nsolid-state chemistry. Framework materials are solids whose structures are\nassembled from nodes and linkers to form scaffolding-like networks. These\nstructures usually contain cavities, which may host additional ions for charge\nbalance. In the well-established systems---such as lead titanate---these\ncomponents are all atomic, but in molecular frameworks, at least one ion is\nmolecular. Here, we survey the unconventional degrees of freedom introduced\nthrough the replacement of atoms by molecules. Our motivation is to understand\nthe role these new distortions play in different materials properties. The\nvarious degrees of freedom are summarised and described in the context of\nexperimental examples. We highlight a number of directions for future research,\nwhich demonstrate the extraordinary possibilities for this nascent field.",
        "positive": "Design of a multifunctional sample probe for transport measurements and\n  technological device characterizations: We describe a multifunctional sample probe for transport measurements,\nequipped with a two-axis goniometer providing computer controlled 360${^\\circ}$\nout of plane and manual 360${^\\circ}$ in-plane rotation. The multifunctional\nsample probe has been successfully implemented to a host dewar and\nelectromagnet system. The developed probe is capable of performing transport\nmeasurements and device characterizations with high flexibility of controlling\nmagnetic and electrical fields, angle, temperature and current/voltage\nparameters in a wide range. The design of the multifunctional sample probe\nallows easy connection of other external devices and easy installation into\nother dewar and magnet systems. A software interface based on NI Labview visual\nprogramming language has been developed to control the system. The setup has\nbeen tested in the hysteresis loop measurements of perpendicularly magnetized\nCo/Pt/CoO ultra-thin films with anomalous Hall effect (AHE) method. We have\nalso performed temperature dependent exchange bias measurements of the samples.\nThe developed probe revealed much better resolution in the case of\nperpendicularly magnetized ultra-thin Co/Pt/CoO films compared to a standard\nvibrating sample magnetometry system."
    },
    {
        "anchor": "Magnetocapacitance effect in perovskite-superlattice based multiferroics: We report the structural and magnetoelectrical properties of\nLa$_{0.7}$Ca$_{0.3}$MnO$_3$/BaTiO$_3$ perovskite superlattices grown on\n(001)-oriented SrTiO$_3$ by the pulsed laser deposition technique. Magnetic\nhysteresis loops together with temperature dependent magnetic properties\nexhibit well-defined coercivity and magnetic transition temperature (T$_C$)\n\\symbol{126}140 K. $DC$ electrical studies of films show that the\nmagnetoresistance (MR) is dependent on the BaTiO$_3$ thickness and negative\n$MR$ as high as 30% at 100K are observed. The $AC$ electrical studies reveal\nthat the impedance and capacitance in these films vary with the applied\nmagnetic field due to the magnetoelectrical coupling in these structures - a\nkey feature of multiferroics. A negative magnetocapacitance value in the film\nas high as 3% per tesla at 1kHz and 100K is demonstrated, opening the route for\ndesigning novel functional materials.",
        "positive": "Study of Growth Properties of InAs Islands on Nucleation Sites Defined\n  by Focused Ion Beam: This work describes morphological and crystalline properties of the InAs\nislands grown on templates created by focused ion beam (FIB) on indium\nphosphide (InP) substrates. Regular arrangements of shallow holes are created\non the InP (001) surfaces, acting as preferential nucleation sites for InAs\nislands grown by Metal-Organic Vapor Phase Epitaxy. Ion doses ranging from\n$10^{15}$ to $10^{16}$ $Ga^{+}$/$cm^{2}$ were used and islands were grown for\ntwo sub-monolayer coverages. We observe the formation of clusters in the inner\nsurfaces of the FIB produced cavities and show that for low doses templates the\nnanostructures are mainly coherent while templates created with large ion doses\nlead to the growth of incoherent islands with larger island density. The\nmodified island growth is described by a simple model based on the surface\npotential and the net adatom flow to the cavities. We observe that obtained\nmorphologies result from a competition between coarsening and coalescence\nmechanisms."
    },
    {
        "anchor": "Critical velocities for deflagration and detonation triggered by voids\n  in a REBO high explosive: The effects of circular voids on the shock sensitivity of a two-dimensional\nmodel high explosive crystal are considered. We simulate a piston impact using\nmolecular dynamics simulations with a Reactive Empirical Bond Order (REBO)\nmodel potential for a sub-micron, sub-ns exothermic reaction in a diatomic\nmolecular solid. The probability of initiating chemical reactions is found to\nrise more suddenly with increasing piston velocity for larger voids that\ncollapse more deterministically. A void with radius as small as 10 nm reduces\nthe minimum initiating velocity by a factor of 4.",
        "positive": "2D titanium carbonitrides and their hydroxylated derivatives:\n  Structural, electronic properties and stability of MXenes Ti3C2-xNx and\n  Ti3C2-xNx(OH)2: 3D titanium carbonitrides TiCxNy possess excellent physical, chemical, and\nmechanical properties, attractive for various industrial applications. Most\nrecently, the uncommon nano-sized layers of 2D-like titanium carbonitrides were\nfabricated from MAX phases. Herein, the structural, electronic properties and\nstability of these new compounds as well as their hydroxylated derivatives -\nso-called MXenes Ti3C2-xNx and Ti3C2-xNx(OH)2 are probed by means of SSC-DFTB\ncalculations. The genesis of the properties is discussed in the sequence:\nbinary MXenes Ti3C2 (Ti3N2) -> their hydroxylated forms Ti3C2(OH)2 (Ti3N2(OH)2)\n-> pristine MXene Ti3C2-xNx -> hydroxylated Ti3C2-xNx(OH)2. Our results show\nthat the examined materials are metallic-like. The most favorable type of\nOH-covering is presented by the occupation of the hollow sites between three\nneighboring carbon (nitrogen) atoms. The formation of 2D MXene carbonitrides\nwith random distribution of C and N atoms was found to be thermodynamically\nmore favorable."
    },
    {
        "anchor": "Effect of co-doping of donor and acceptor impurities in the\n  ferromagnetic semiconductor Zn1-xCrxTe studied by soft x-ray magnetic\n  circular dichroism: We have performed x-ray absorption spectroscopy (XAS) and x-ray magnetic\ncircular dichroism (XMCD) studies of the diluted ferromagnetic semiconductor\nZn$_{1-\\textit{x}}$Cr$_\\textit{x}$Te doped with iodine (I) or nitrogen (N),\ncorresponding to electron or hole doping, respectively. From the shape of the\nCr $2p$ absorption peak in the XAS spectra, it was concluded that Cr ions in\nthe undoped, I-doped and lightly N-doped samples are divalent (Cr$^{2+}$),\nwhile Cr$^{2+}$ and trivalent (Cr$^{3+}$) coexist in the heavily N-doped\nsample. This result indicates that the doped nitrogen atoms act as acceptors\nbut that doped holes are located on the Cr ions. In the magnetic-field\ndependence of the XMCD signal at the Cr $2p$ absorption edge, ferromagnetic\nbehaviors were observed in the undoped, I-doped, and lightly N-doped samples,\nwhile ferromagnetism was considerably suppressed in heavily N-doped sample,\nwhich is consistent with the results of magnetization measurements.",
        "positive": "BioinspiredLLM: Conversational Large Language Model for the Mechanics of\n  Biological and Bio-inspired Materials: The study of biological materials and bio-inspired materials science is well\nestablished; however, surprisingly little knowledge has been systematically\ntranslated to engineering solutions. To accelerate discovery and guide\ninsights, an open-source autoregressive transformer large language model (LLM),\nBioinspiredLLM, is reported. The model was finetuned with a corpus of over a\nthousand peer-reviewed articles in the field of structural biological and\nbio-inspired materials and can be prompted to recall information, assist with\nresearch tasks, and function as an engine for creativity. The model has proven\nthat it is able to accurately recall information about biological materials and\nis further enhanced with enhanced reasoning ability, as well as with\nretrieval-augmented generation to incorporate new data during generation that\ncan also help to traceback sources, update the knowledge base, and connect\nknowledge domains. BioinspiredLLM also has been shown to develop sound\nhypotheses regarding biological materials design and remarkably so for\nmaterials that have never been explicitly studied before. Lastly, the model\nshowed impressive promise in collaborating with other generative artificial\nintelligence models in a workflow that can reshape the traditional materials\ndesign process. This collaborative generative artificial intelligence method\ncan stimulate and enhance bio-inspired materials design workflows. Biological\nmaterials are at a critical intersection of multiple scientific fields and\nmodels like BioinspiredLLM help to connect knowledge domains."
    },
    {
        "anchor": "Overhauser's spin-density wave in exact-exchange spin density functional\n  theory: The spin density wave (SDW) state of the uniform electron gas is investigated\nin the exact exchange approximation of noncollinear spin density functional\ntheory (DFT). Unlike in Hartree-Fock theory, where the uniform paramagnetic\nstate of the electron gas is unstable against formation of the spin density\nwave for all densities, in exact-exchange spin-DFT this instability occurs only\nfor densities lower than a critical value. It is also shown that, although in a\nsuitable density range it is possible to find a non-interacting SDW ground\nstate Slater determinant with energy lower than the corresponding paramagnetic\nstate, this Slater determinant is not a self-consistent solution of the\nOptimized Effective Potential (OEP) integral equations of noncollinear\nspin-DFT. A selfconsistent solution of the OEP equations which gives an even\nlower energy can be found using an excited-state Slater determinant where only\norbitals with single-particle energies in the lower of two bands are occupied\nwhile orbitals in the second band remain unoccupied even if their energies are\nbelow the Fermi energy.",
        "positive": "High-entropy alloy TiV2ZrCrMnFeNi for hydrogen storage at room\n  temperature with full reversibility and good activation: The development of alloys that are hydrogenated and dehydrogenated quickly\nand actively at room temperature is a challenge for the safe and compact\nstorage of hydrogen. In this study, a new high-entropy alloy (HEA) with AB-type\nconfiguration (A: hydride-forming elements, B: inert-to-hydrogen elements) was\ndesigned by considering valence electron concentration, electronegativity\ndifference and atomic-size mismatch of elements. The alloy TiV2ZrCrMnFeNi had\ndual C14 Laves and BCC phases, in which C14 stored hydrogen and BCC/C14\ninterphase boundaries contributed to activation. The alloy absorbed 1.6 wt% of\nhydrogen at room temperature without any activation treatment and exhibited\nfast kinetics and full reversibility."
    },
    {
        "anchor": "Two-dimensional electron-gas-like charge transport at magnetic Heusler\n  alloy-SrTiO$_3$ interface: We report remarkably low residual resistivity, giant residual resistivity\nratio, free-electron-like Hall resistivity and high mobility ($\\approx$ 10$^4$\ncm$^2$V$^{-1}$s$^{-1}$) charge transport in epitaxial films of Co$_2$MnSi and\nCo$_2$FeSi grown on (001) SrTiO$_3$. This unusual behavior is not observed in\nfilms deposited on other cubic oxide substrates of comparable lattice\nparameters. The scaling of the resistivity with thickness of the films allow\nextraction of interface conductance, which can be attributed to a layer of\noxygen vacancies confined within 1.9 nm of the interface as revealed by\natomically resolved electron microscopy and spectroscopy. The high mobility\ntransport observed here at the interface of a fully spin polarized metal is\npotentially important for spintronics applications.",
        "positive": "Optical properties of random alloys : A formulation: We present here a formulation for the calculation of the\nconfiguration-averaged optical conductivity in random alloys. Our formulation\nis based on the augmented-space theorem introduced by one of us [A. Mookerjee,\nJ. Phys. C: Solid State Phys. 6, 1340 (1973)]. We show that disorder scattering\nrenormalizes the electron and hole propagators as well as the transition\namplitude. The corrections to the transition amplitude have been shown to be\nrelated to the self-energy of the propagators and vertex corrections."
    },
    {
        "anchor": "Monitoring of the formation of strontium molybdate intergrain tunneling\n  barriers in strontium ferromolybdate: This work is a contribution to the understanding of the electrical\nresistivity in strontium ferromolybdate (SFMO) ceramics. It demonstrates that\nan appropriate thermal treatment leads to the formation of dielectric SrMoO4\nshells at the surface of SFMO nanograins. In samples without SrMoO4 shells, the\nsign of the temperature coefficient of resistance changes with increasing\ntemperature from negative at very low temperature to positive at higher\ntemperatures. Samples exhibiting a negative temperature coefficient contain\nSrMoO4 shells and demonstrate a behavior of the resistivity that can be\ndescribed in terms of the fluctuation-induced tunneling model, and near room\ntemperature the conductivity mechanism converts to a variable-range hopping\none. The results of this work serve as a starting point for the understanding\nof the low-field magnetoresistance which is very promising for spintronic\ndevice application.",
        "positive": "Thermodynamic and transport properties of single crystalline\n  RCo$_{2}$Ge$_{2}$ (R = Y, La-Nd, Sm-Tm): Single crystals of RCo$_{2}$Ge$_{2}$ (R = Y, La-Nd, Sm-Tm) were grown using a\nself-flux method and were characterized by room-temperature powder x-ray\ndiffraction; anisotropic, temperature and field dependent magnetization;\ntemperature and field dependent, in-plane resistivity; and specific heat\nmeasurements. In this series, the majority of the moment-bearing members order\nantiferromagnetically; YCo$_{2}$Ge$_{2}$ and LaCo$_{2}$Ge$_{2}$ are\nnon-moment-bearing. Ce is trivalent in CeCo$_{2}$Ge$_{2}$ at high temperatures,\nand exhibits an enhanced electronic specific heat coefficient due to Kondo\neffect at low temperatures. In addition, CeCo$_{2}$Ge$_{2}$ shows two\nlow-temperature anomalies in temperature-dependent magnetization and specific\nheat measurements. Three members (R = Tb-Ho) have multiple phase transitions\nabove 1.8 K. Eu appears to be divalent with total angular momentum L = 0. Both\nEuCo$_{2}$Ge$_{2}$ and GdCo$_{2}$Ge$_{2}$ manifest essentially isotropic\nparamagnetic properties consistent with J = S = 7/2. Clear magnetic anisotropy\nfor rare-earth members with finite L was observed, with ErCo$_{2}$Ge$_{2}$ and\nTmCo$_{2}$Ge$_{2}$ manifesting planar anisotropy and the rest members\nmanifesting axial anisotropy. The experimentally estimated crystal electric\nfield (CEF) parameters B$_{2}^{0}$ were calculated from the anisotropic\nparamagnetic $\\theta_{ab}$ and $\\theta_{c}$ values and follow a trend that\nagrees well with theoretical predictions. The ordering temperatures, T$_{N}$,\nas well as the polycrystalline averaged paramagnetic Curie-Weiss temperature,\n$\\Theta_{avg}$, for the heavy rare-earth members deviate from the de Gennes\nscaling, as the magnitude of both are the highest for Tb, which is sometimes\nseen for extremely axial systems. Except for SmCo$_{2}$Ge$_{2}$, metamagnetic\ntransitions were observed at 1.8 K for all members that ordered\nantiferromagnetically."
    },
    {
        "anchor": "Light Induced Electron-Phonon Scattering Mediated Resistive Switching in\n  Nanostructured Nb Thin Film Superconductor: The elemental Nb is mainly investigated for its eminent superconducting\nproperties. In contrary, we report of a relatively unexplored property, namely,\nits superior optoelectronic property in reduced dimension. We demonstrate here\nthat nanostructured Nb thin films (NNFs), under optical illumination, behave as\nroom temperature photo-switches and exhibit bolometric features below its\nsuperconducting critical temperature. Both photo-switch and superconducting\nbolometric behavior are monitored by its resistance change with light in\nvisible and near infrared (NIR) wavelength range. Unlike the conventional\nphotodetectors, the NNF devices switch to higher resistive states with light\nand the corresponding resistivity change is studied with thickness and grain\nsize variations. At low temperature in its superconducting state, the light\nexposure shifts the superconducting transition towards lower temperature. The\nroom temperature photon sensing nature of the NNF is explained by the photon\nassisted electron-phonon scattering mechanism while the low temperature light\nresponse is mainly related to the heat generation which essentially changes the\neffective temperature for the device and the device is capable of sensing a\ntemperature difference of few tens of milli-kelvins. The observed\nphoto-response on the transport properties of NNFs can be very important for\nfuture superconducting photon detectors, bolometers and phase slip based device\napplications.",
        "positive": "Gate-tunable van der Waals heterostructure for reconfigurable neural\n  network vision sensor: Early processing of visual information takes place in the human retina.\nMimicking neurobiological structures and functionalities of the retina provide\na promising pathway to achieving vision sensor with highly efficient image\nprocessing. Here, we demonstrate a prototype vision sensor that operates via\nthe gate-tunable positive and negative photoresponses of the van der Waals\n(vdW) vertical heterostructures. The sensor emulates not only the\nneurobiological functionalities of bipolar cells and photoreceptors but also\nthe unique synaptic connectivity between bipolar cells and photoreceptors. By\ntuning gate voltage for each pixel, we achieve reconfigurable vision sensor for\nsimultaneously image sensing and processing. Furthermore, our prototype vision\nsensor itself can be trained to classify the input images, via updating the\ngate voltages applied individually to each pixel in the sensor. Our work\nindicates that vdW vertical heterostructures offer a promising platform for the\ndevelopment of neural network vision sensor."
    },
    {
        "anchor": "Characteristics of Precession Electron Diffraction Intensities from\n  Dynamical Simulations: Precession Electron Diffraction (PED) offers a number of advantages for\ncrystal structure analysis and solving unknown structures using electron\ndiffraction. The current article uses many-beam simulations of PED intensities,\nin combination with model structures, to arrive at a better understanding of\nhow PED differs from standard unprecessed electron diffraction. It is shown\nthat precession reduces the chaotic oscillatory behavior of electron\ndiffraction intensities as a function of thickness. An additional\ncharacteristic of PED which is revealed by simulations is reduced sensitivity\nto structure factor phases. This is shown to be a general feature of dynami-cal\nintensities collected under conditions in which patterns with multiple incident\nbeam orienta-tions are averaged together. A new and significantly faster method\nis demonstrated for dynami-cal calculations of PED intensities, based on using\ninformation contained in off-central columns of the scattering matrix.",
        "positive": "$\u03bc$2mech: a Software Package Combining Microstructure Modeling and\n  Mechanical Property Prediction: We have developed a graphical user interface (GUI) based package $\\mu$2mech\nto perform phase-field simulation for predicting microstructure evolution. The\npackage can take inputs from ab initio calculations and CALPHAD (Calculation of\nPhase Diagrams) tools for quantitative microstructure prediction. The package\nalso provides a seamless connection to transfer output from the mesoscale phase\nfield method to the microscale finite element analysis for mechanical property\nprediction. Such a multiscale simulation package can facilitate\nmicrostructure-property correlation, one of the cornerstones in accelerated\nmaterials development within the integrated computational materials engineering\n(ICME) framework."
    },
    {
        "anchor": "Strain localization and shear banding in ductile materials: A model of a shear band as a zero-thickness nonlinear interface is proposed\nand tested using finite element simulations. An imperfection approach is used\nin this model where a shear band, that is assumed to lie in a ductile matrix\nmaterial (obeying von Mises plasticity with linear hardening), is present from\nthe beginning of loading and is considered to be a zone in which yielding\noccurs before the rest of the matrix. This approach is contrasted with a\nperturbative approach, developed for a J$_2$-deformation theory material, in\nwhich the shear band is modelled to emerge at a certain stage of a uniform\ndeformation. Both approaches concur in showing that the shear bands\n(differently from cracks) propagate rectilinearly under shear loading and that\na strong stress concentration should be expected to be present at the tip of\nthe shear band, two key features in the understanding of failure mechanisms of\nductile materials.",
        "positive": "Ferromagnetic-like behavior of Bi0.9La0.1FeO3-KBr nanocomposites: We studied magnetostatic response of the Bi0.9La0.1FeO3-KBr composites\n(BLFO-KBr) consisting of nanosized (about 100 nm) ferrite Bi0.9La0.1FeO3 (BLFO)\nconjugated with fine grinded ionic conducting KBr. When the fraction of KBr is\nrather small (less than 15 wt percent) the magnetic response of the composite\nis very weak and similar to that observed for the BLFO (pure KBr matrix without\nBi1-xLaxFeO3 has no magnetic response as anticipated). However, when the\nfraction of KBr increases above 15percent, the magnetic response of the\ncomposite changes substantially and the field dependence of magnetization\nreveals ferromagnetic-like hysteresis loop with a remanent magnetization about\n0.14 emu/g and coercive field about 1.8 Tesla (at room temperature). Nothing\nsimilar to the ferromagnetic-like hysteresis loop can be observed in BLFO\nceramics, which magnetization quasi linearly increases with magnetic field.\nDifferent physical mechanisms were considered to explain the unusual\nexperimental results for BLFO-KBr nanocomposites, but only those among them,\nwhich are highly sensitive to the interaction of antiferromagnetic\nBi0.9La0.1FeO3 with ionic conductor KBr, can be relevant. An appropriate\nmechanism turned out to be ferro-magneto-ionic coupling."
    },
    {
        "anchor": "Correlated defects, metal-insulator transition, and magnetic order in\n  ferromagnetic semiconductors: The effect of disorder on transport and magnetization in ferromagnetic III-V\nsemiconductors, in particular (Ga,Mn)As, is studied theoretically. We show that\nCoulomb-induced correlations of the defect positions are crucial for the\ntransport and magnetic properties of these highly compensated materials. We\nemploy Monte Carlo simulations to obtain the correlated defect distributions.\nExact diagonalization gives reasonable results for the spectrum of valence-band\nholes and the metal-insulator transition only for correlated disorder. Finally,\nwe show that the mean-field magnetization also depends crucially on defect\ncorrelations.",
        "positive": "Magnetism in Transition metal doped Cubic SiC: We report here our study on SiC doped with transition metals using first\nprinciple density functional theory calculations. We have considered cubic SiC\nwith 3d transition metals as substitutional impurities for Si and C site\nseparately. Cubic SiC doped with Cr, Mn, show ferromagnetism whereas with Sc,\nTi, V and Co show site dependency of magnetic properties. Rests of the\nimpurities are found to be non-magnetic."
    },
    {
        "anchor": "Alloying behavior of wide band gap alkaline-earth chalcogenides: Alloying is a powerful tool for tuning materials that facilitates the\ntargeted design of desirable properties for a variety of applications. In this\nwork, we provide a comprehensive investigation of the synthetic accessibility\nand electronic properties of nine alkaline-earth chalcogenide anion alloys\n(CaS$_{1-x}$O$_x$, CaS$_{1-x}$Se$_x$, CaS$_{1-x}$Te$_x$, SrS$_{1-x}$O$_x$,\nSrS$_{1-x}$Se$_x$, SrS$_{1-x}$Te$_x$, MgS$_{1- x}$O$_x$, MgS$_{1-x}$Se$_x$, and\nMgS$_{1-x}$Te$_x$). We show that isostructural alloying within the rock salt\nstructure is favored for all systems except MgS$_{1-x}$Te$_x$, which is\npredicted to be a heterostructural alloy between the rock salt and wurtzite\nstructures. Alloys of S and Se are shown to be readily accessible for all\ncations with low miscibility critical temperatures, enabling continuous tuning\nof electronic properties across this composition space. Alloys of S and Te have\nhigher critical temperatures but may be accessible through non-equilibrium\nsynthesis strategies and are predicted here to have desirable electronic\nproperties for optoelectronics with wide band gaps and lower effective masses\nthan alloys of S and Se. Anion alloying in MgS$_{1-x}$Te$_x$ stabilizes the\nwurtzite structure across a significant fraction of composition space, which\nmay make it of particular interest as a transparent conducting material due to\nits lower effective masses and a higher band gap than the rock salt structure.\nZero-point corrected random phase approximation (RPA) energies were computed to\nresolve the small polymorph energy differences of the Mg compounds and are\nshown to be critical for accurately describing the thermodynamic properties of\nthe corresponding alloys.",
        "positive": "Robust noncoplanar magnetism in band filling-tuned\n  (Nd$_{1-x}$Ca$_x$)$_2$Mo$_2$O$_7$: In the metallic pyrochlore Nd$_2$Mo$_2$O$_7$, the conducting Molybdenum\nsublattice adopts canted, yet nearly collinear ferromagnetic order with nonzero\nscalar spin chirality. The chemical potential may be controlled by replacing\nNd$^{3+}$ with Ca$^{2+}$, while introducing only minimal additional disorder to\nthe conducting states. Here, we demonstrate the stability of the canted\nferromagnetic state, including the tilting angle of Molybdenum spins, in\n(Nd$_{1-x}$Ca$_{x}$)$_2$Mo$_2$O$_7$ (NCMO) with $x\\le 0.15$ using magnetic\nsusceptibility measurements. Mo-Mo and Mo-Nd magnetic couplings both change\nsign above $x=0.22$, where the canted ferromagnetic state gives way to a\nspin-glass metallic region. Contributions to the Curie-Weiss law from two\nmagnetic sublattices are separated systematically."
    },
    {
        "anchor": "Neutron diffraction study of stability and phase transitions in Cu-Sn-In\n  alloys as alternative Pb-free solders: In this work we present an experimental study of structure and phase\nstability in ternary Cu-Sn-In alloys around 55 at.% Cu in the temperature range\n100^{\\circ}C < T < 550^{\\circ}C. We have followed in real-time the sequence of\nphase transformations in succesive heating and cooling ramps, using\nstate-of-the-art neutron powder thermodiffractometry. These experiments were\ncomplemented with calorimetric studies of the same alloys. Our results give\nexperimental support to the current assessment of the ternary phase diagram in\nthis composition and temperature range, yielding the sequence of transitions\n\\eta -> \\eta + L -> \\epsilon + L with transformation temperatures of\n210^{\\circ}C and 445^{\\circ}C, respectively. The use of neutrons allowed to\novercome common difficulties in phase identification with powder XRD due to\nabsorption and preferred orientation issues. Even the transitions to liquid\nphases could be successfully identified and monitored in situ, turning this\ntechnique into a valuable tool for phase diagram studies of emerging lead-free\nsolder candidates.",
        "positive": "Spin injection from the Heusler alloy Co_2MnGe into Al_0.1Ga_0.9As/GaAs\n  heterostructures: Electrical spin injection from the Heusler alloy Co_2MnGe into a p-i-n\nAl_0.1Ga_0.9As/GaAs light emitting diode is demonstrated. A maximum\nsteady-state spin polarization of approximately 13% at 2 K is measured in two\ntypes of heterostructures. The injected spin polarization at 2 K is calculated\nto be 27% based on a calibration of the spin detector using Hanle effect\nmeasurements. Although the dependence on electrical bias conditions is\nqualitatively similar to Fe-based spin injection devices of the same design,\nthe spin polarization injected from Co_2MnGe decays more rapidly with\nincreasing temperature."
    },
    {
        "anchor": "Hysteretic effects and magnetotransport of electrically switched CuMnAs: Antiferromagnetic spintronics allows us to explore storing and processing\ninformation in magnetic crystals with vanishing magnetization. In this\nmanuscript, we investigate magnetoresistance effects in antiferromagnetic\nCuMnAs upon switching into high-resistive states using electrical pulses. By\nemploying magnetic field sweeps up to 14 T and magnetic field pulses up to\n$\\sim$ 60 T, we reveal hysteretic phenomena and changes in the\nmagnetoresistance, as well as the resilience of the switching signal in CuMnAs\nto the high magnetic field. These properties of the switched state are\ndiscussed in the context of recent studies of antiferromagnetic textures in\nCuMnAs.",
        "positive": "Evaluation of the optical conductivity tensor in terms of contour\n  integrations: For the case of finite life-time broadening the standard Kubo-formula for the\noptical conductivity tensor is rederived in terms of Green's functions by using\ncontour integrations, whereby finite temperatures are accounted for by using\nthe Fermi-Dirac distribution function. For zero life-time broadening, the\npresent formalism is related to expressions well-known in the literature.\nNumerical aspects of how to calculate the corresponding contour integrals are\nalso outlined."
    },
    {
        "anchor": "Orientation-dependent stabilization of MgCr$_2$O$_4$ spinel thin films: AB$_2$O$_4$ normal spinels with a magnetic B site can host a variety of\nmagnetic and orbital frustrations leading to spin-liquid phases and\nfield-induced phase transitions. Here we report the first epitaxial growth of\n(111)-oriented MgCr$_2$O$_4$ thin films. By characterizing the structural and\nelectronic properties of films grown along (001) and (111) directions, the\ninfluence of growth orientation has been studied. Despite distinctly different\ngrowth modes observed during deposition, the comprehensive characterization\nreveals no measurable disorder in the cation distribution nor multivalency\nissue for Cr ions in either orientation. Contrary to a naive expectation, the\n(111) stabilized films exhibit a smoother surface and a higher degree of\ncrystallinity than (001)-oriented films. The preference in growth orientation\nis explained within the framework of heteroepitaxial stabilization in\nconnection to a significantly lower (111) surface energy. These findings open\nbroad opportunities in the fabrication of 2D kagome-triangular heterostructures\nwith emergent magnetic behavior inaccessible in bulk crystals.",
        "positive": "Nitrogen oxides under pressure stability, ionization, polymerization,\n  and superconductivity: Nitrogen oxides are textbook class of molecular compounds, with extensive\nindustrial applications. Nitrogen and oxygen are also among the most abundant\nelements in the universe. We explore the N-O system at 0 K and up to 500 GPa\nthough ab initio evolutionary simulations. Results show that two phase\ntransformations of stable molecular NO2 exist at 7 and 64 GPa, and followed by\ndecomposition of NO2 at 91 GPa. All of the NO+NO3- structures are found to be\nmetastable at T=0 K, so experimentally reported ionic NO+NO3- is either\nmetastable or stabilized by temperature. Upon increasing pressure, N2O5\ntransforms from P-1 to C2/c structure at 51 GPa. NO becomes thermodynamically\nstable at 198 GPa. This polymeric phase is superconducting (Tc = 2.0 K) and\ncontains a -N-N- backbone."
    },
    {
        "anchor": "Chain Conformation and Exciton Delocalization in a Push-Pull Conjugated\n  Polymer: Linear and nonlinear optical lineshapes reveal details of excitonic structure\nin semiconductor polymers. We implement absorption, photoluminescence, and\ntransient absorption spectroscopies in DPP-DTT, an electron push-pull\ncopolymer, to explore the relationship between their spectral lineshapes and\nchain conformation, deduced from resonance Raman spectroscopy and from\n\\textit{ab initio} calculations. The viscosity of precursor polymer solutions\nbefore film casting displays a transition that suggests gel formation above a\ncritical concentration. Upon crossing this viscosity deflection concentration,\nthe lineshape analysis of the absorption spectra within a photophysical\naggregate model reveals a gradual increase in interchain excitonic coupling. We\nalso observe a red-shifted and line-narrowed steady-state photoluminescence\nspectrum, along with increasing resonance Raman intensity in the stretching and\ntorsional modes of the dithienothiphene unit, which suggests a longer exciton\ncoherence length along the polymer-chain backbone. Furthermore, we observe a\nchange of lineshape in the photoinduced absorption component of the transient\nabsorption spectrum. The derivative-like lineshape may originate from two\npossibilities: a new excited-state absorption, or from optical Stark effect,\nboth of which are consistent with the emergence of high-energy shoulder as seen\nin both photoluminescence and absorption spectra. Therefore, we conclude that\nthe exciton is more dispersed along the polymer chain backbone with increasing\nconcentrations, leading to the hypothesis that the polymer chain order is\nenhanced when the push-pull polymers are processed at higher concentrations.\nThus, tuning the microscopic chain conformation by concentration would be\nanother factor of interest when considering the polymer assembly pathways for\npursuing large-area and high-performance organic optoelectronic devices.",
        "positive": "Large adiabatic temperature and magnetic entropy changes in EuTiO3: We have investigated the magnetocaloric effect in single and polycrystalline\nsamples of quantum paraelectric EuTiO3 by magnetization and heat capacity\nmeasurements. Single crystalline EuTiO3 shows antiferromagnetic ordering due to\nEu2+ magnetic moments below TN = 5.6 K. This compound shows a giant\nmagnetocaloric effect around its Neel temperature. The isothermal magnetic\nentropy change is 49 Jkg-1K-1, the adiabatic temperature change is 21 K and the\nrefrigeration capacity is 500 JKg-1 for a field change of 7 T at TN. The single\ncrystal and polycrystalline samples show similar values of the magnetic entropy\nchange and adiabatic temperature changes. The large magnetocaloric effect is\ndue to suppression of the spin entropy associated with localized 4f moment of\nEu2+ ions. The giant magnetocaloric effect together with negligible hysteresis,\nsuggest that EuTiO3 could be a potential material for magnetic refrigeration\nbelow 20 K."
    },
    {
        "anchor": "Anisotropic terahertz optostriction in group-IV monochalcogenide\n  compounds: Terahertz (THz) technology is a cutting-edge scheme with various promising\napplications, such as next generation telecommunication, non-destructive\nevaluation, security check, and in-depth characterization, owing to their\nsensitivity to material geometric change and good transparency. Even though\ntremendous progresses have been made during the past decade, exploration the\nmechanisms of THz-matter interaction microscopically is still in its infancy.\nIn this work, we use thermodynamic theory to show how THz illumination deforms\nmaterials and use group-IV monochalcogenide compounds to illustrate it.\nAccording to our first-principles density functional theory calculations, THz\nlight with intermediate intensity (~109 W/cm2) could yield elastic deformations\non the order of ~0.1%, depending on laser polarization direction. Large\nanisotropic opto-mechanical responses are also revealed. Finally, we show that\nsuch strain can be detected via measuring the layer-resolved shift current\nunder a probe light irradiation.",
        "positive": "Two channel model for optical conductivity of high mobility organic\n  crystals: We show that the temperature dependence of conductivity of high mobility\norganic crystals Pentacene and Rubrene can be quantitatively described in the\nframework of the model where carriers are scattered by quenched local\nimpurities and interact with phonons by Su-Schrieffer-Hegger (SSH) coupling.\nWithin this model, we present approximation free results for mobility and\noptical conductivity obtained by world line Monte Carlo, which we generalize to\nthe case of coupling both to phonons and impurities. We find fingerprints of\ncarrier dynamics in these compounds which differ from conventional metals and\nshow that the dynamics of carriers can be described as a superposition of a\nDrude term representing diffusive mobile particles and a Lorentz term\nassociated with dynamics of localized charges."
    },
    {
        "anchor": "Numerical computations of facetted pattern formation in snow crystal\n  growth: Facetted growth of snow crystals leads to a rich diversity of forms, and\nexhibits a remarkable sixfold symmetry. Snow crystal structures result from\ndiffusion limited crystal growth in the presence of anisotropic surface energy\nand anisotropic attachment kinetics. It is by now well understood that the\nmorphological stability of ice crystals strongly depends on supersaturation,\ncrystal size and temperature. Until very recently it was very difficult to\nperform numerical simulations of this highly anisotropic crystal growth. In\nparticular, obtaining facet growth in combination with dendritic branching is a\nchallenging task. We present numerical simulations of snow crystal growth in\ntwo and three space dimensions using a new computational method recently\nintroduced by the authors. We present both qualitative and quantitative\ncomputations. In particular, a linear relationship between tip velocity and\nsupersaturation is observed. The computations also suggest that surface energy\neffects, although small, have a larger effect on crystal growth than previously\nexpected. We compute solid plates, solid prisms, hollow columns, needles,\ndendrites, capped columns and scrolls on plates. Although all these forms\nappear in nature, most of these forms are computed here for the first time in\nnumerical simulations for a continuum model.",
        "positive": "Oxidation-assisted graphene heteroepitaxy on copper foil: We propose an innovative, easy-to-implement approach to synthesize large-area\nsinglecrystalline graphene sheets by chemical vapor deposition on copper foil.\nThis method doubly takes advantage of residual oxygen present in the gas phase.\nFirst, by slightly oxidizing the copper surface, we induce grain boundary\npinning in copper and, in consequence, the freezing of the thermal\nrecrystallization process. Subsequent reduction of copper under hydrogen\nsuddenly unlocks the delayed reconstruction, favoring the growth of\ncentimeter-sized copper (111) grains through the mechanism of abnormal grain\ngrowth. Second, the oxidation of the copper surface also drastically reduces\nthe nucleation density of graphene. This oxidation/reduction sequence leads to\nthe synthesis of aligned millimeter-sized monolayer graphene domains in\nepitaxial registry with copper (111). The as-grown graphene flakes are\ndemonstrated to be both single-crystalline and of high quality."
    },
    {
        "anchor": "Strain gradient plasticity modeling of hydrogen diffusion to the crack\n  tip: In this work hydrogen diffusion towards the fracture process zone is examined\naccounting for local hardening due to geometrically necessary dislocations\n(GNDs) by means of strain gradient plasticity (SGP). Finite element\ncomputations are performed within the finite deformation theory to characterize\nthe gradient-enhanced stress elevation and subsequent diffusion of hydrogen\ntowards the crack tip. Results reveal that GNDs, absent in conventional\nplasticity predictions, play a fundamental role on hydrogen transport ahead of\na crack. SGP estimations provide a good agreement with experimental\nmeasurements of crack tip deformation and high levels of lattice hydrogen\nconcentration are predicted within microns to the crack tip. The important\nimplications of the results in the understanding of hydrogen embrittlement\nmechanisms are thoroughly discussed.",
        "positive": "Self-assembled chiral phosphorus nanotubes from phosphorene: a molecular\n  dynamics study: Controlled syntheses in nanoscale structures should be expected and\nphosphorous nanotubes with predefined chiralities are important in electronic\ndevices with tunable bandgap. Here, incorporating molecular dynamics\nsimulations with theoretical analyses, we show that a zigzag phosphorene\nnanoribbon can self-assemble and form a corresponding chiral phosphorous\nnanotube surrounding a template armchair phosphorous nanotube. The van der\nWaals potential between the nanoribbon and the nanotube is transformed to the\nintrinsic deformed and chemical bonding energies of the synthesized tube\ntogether with partial kinetic energy. The self-assembly process has an apparent\ntemperature dependence and size effect and the formed chiral tube is\nthermodynamically stable. Also, the chirality and measurement can be tuned by\nthe radius of template tube and the aspect ratio of raw ribbon. The study\nsuggests a novel and feasible approach for controlled synthesis of phosphorous\nnanotubes and thus is of great interest for semiconductor device applications."
    },
    {
        "anchor": "Electrical current switching of the noncollinear antiferromagnet\n  Mn$_3$GaN: We report electrical current switching of noncollinear antiferromagnetic\n(AFM) Mn$_3$GaN/Pt bilayers at room temperature. The Hall resistance of these\nbilayers can be manipulated by applying a pulse current of\n$1.5\\times10^6$~A/cm$^2$, whereas no significant change is observed up to\n$\\sim10^8$~A/cm$^2$ in Mn$_3$GaN single films, indicating that the Pt layer\nplays an important role. In comparison with ferrimagnetic Mn$_3$GaN/Pt\nbilayers, a lower electrical current switching of noncollinear AFM Mn$_3$GaN is\ndemonstrated, with a critical current density two orders of magnitude smaller.\nOur results highlight that a combination of a noncollinear AFM antiperovskite\nnitride and a spin-torque technique is a good platform of AFM spintronics.",
        "positive": "Contributions of point defects, chemical disorder, and thermal\n  vibrations to electronic properties of Cd(1-x)Zn(x)Te alloys: We present a first principles study based on density functional theory of\nthermodynamic and electronic properties of the most important intrinsic defects\nin the semiconductor alloy Cd(1-x)Zn(x)Te with x<0.13. The alloy is represented\nby a set of supercells with disorder on the Cd/Zn sublattice. Defect formation\nenergies as well as electronic and optical transition levels are analyzed as a\nfunction of composition. We show that defect formation energies increase with\nZn content with the exception of the neutral Te vacancy. This behavior is\nqualitatively similar to but quantitatively rather different from the effect of\nvolumetric strain on defect properties in pure CdTe. Finally, the relative\ncarrier scattering strengths of point defects, alloy disorder, and phonons are\nobtained. It is demonstrated that for realistic defect concentrations carrier\nmobilities are limited by phonon scattering for temperature above approximately\n150 K."
    },
    {
        "anchor": "First Principles Study of Adsorption of $O_{2}$ on Al Surface with\n  Hybrid Functionals: Adsorption of $O_{2}$ molecule on Al surface has been a long standing puzzle\nfor the first principles calculation. We have studied the adsorption of $O_{2}$\nmolecule on the Al(111) surface using hybrid functionals. In contrast to the\nprevious LDA/GGA, the present calculations with hybrid functionals successfully\npredict that $O_{2}$ molecule can be absorbed on the Al(111) surface with a\nbarrier around 0.2$\\thicksim$0.4 eV, which is in good agreement with\nexperiments. Our calculations predict that the LUMO of $O_{2}$ molecule is\nhigher than the Fermi level of the Al(111) surface, which is responsible for\nthe barrier of the $O_{2}$ adsorption.",
        "positive": "Quasicrystal approximants with novel compositions and structures: We identify several new quasicrystal approximants in alloy systems in which\nquasicrystals have not been previously reported. Some occur in alloys with\nlarge size contrast between the constituent elements, either containing small\nBoron atoms, or large Ca/Eu atoms, leading to quasicrystal structures quite\ndifferent from currently known systems where the size contrast is smaller.\nAnother group of the approximants are layered Frank--Kasper structures,\ndemonstrating competition between decagonal and dodecagonal ordering within\nthis family of structures."
    },
    {
        "anchor": "Two-dimensional ferromagnetic semiconductor Cr2XP: First-principles\n  calculations and Monte Carlo simulations: According to the Mermin Wagner theorem, two-dimensional material is difficult\nto have the Curie temperature above room temperature. By using the method of\nband engineering, we design a promising two-dimensional ferromagnetic\nsemiconductor Cr2XP (X=P, As, Sb) with large magnetization, high Curie\ntemperature and sizable band gap. The formation of gap is discussed in terms of\nthe hybridizations, occupation and distribution of electronic states and charge\ntransfer. Large magnetic moments about 6.16~6.37uB origin from the occupation\nof Cr-d electrons in crystal field.Competition and cooperation between d-d\n(Cr-d~Cr-d) and d-p-d (Cr-d~X-p~Cr-d) exchange interactions lead to the\nemergence of ferromagnetic ordering phase. Furthermore, Curie temperatures,\napproaching to 269 K, 332 K and 400 K for Cr2P2, Cr2AsP and Cr2SbP, are\nestimated by employing Monte Carlo simulation based on the Heisenberg model.\nMagnetic anisotropy energy of Cr2XP is determined by calculating the total\nenergy dependence on the angle along different directions, and the origin is\nalso discussed by the second-order perturbation theory. In addition, the Cr2XP\npossesses excellent thermodynamical, dynamical and mechanical stabilities, and\ncan overcome their own gravity to keep their planar structure without the\nsupport of substrate. These above-mentioned advantages will offer some valuable\nhints for two-dimensional ferromagnetic semiconductor Cr2XP in spintronic\ndevices.",
        "positive": "Fast Fourier Transform computations and build-up of plastic deformation\n  in 2D, elastic-perfectly plastic, pixelwise disordered porous media: Stress and strain fields in a two-dimensional pixelwise disordered system are\ncomputed by a Fast Fourier Transform method. The system, a model for a ductile\ndamaged medium, consists of an elastic-perfectly matrix containing void pixels.\nIts behavior is investigated under equibiaxial or shear loading. We monitor the\nevolution with loading of plastically deformed zones, and we exhibit a\nnucleation / growth / coalescence scenario of the latter. Identification of\nplastic ``clusters'' is eased by using a discrete Green function implementing\nequilibrium and continuity at the level of one pixel. Observed morphological\nregimes are put into correspondence with some features of the macroscopic\nstress / strain curves."
    },
    {
        "anchor": "Super-geometric electron focusing on the hexagonal Fermi surface of\n  PdCoO$_2$: Geometric electron optics may be implemented in solid state when transport is\nballistic on the length scale of a device. Currently, this is realized mainly\nin 2D materials characterized by circular Fermi surfaces. Here we demonstrate\nthat the nearly perfectly hexagonal Fermi surface of PdCoO2 gives rise to\nhighly directional ballistic transport. We probe this directional ballistic\nregime in a single crystal of PdCoO2 by use of focused ion beam (FIB)\nmicro-machining, defining crystalline ballistic circuits with features as small\nas 250nm. The peculiar hexagonal Fermi surface naturally leads to electron\nself-focusing effects in a magnetic field, well below the geometric limit\nassociated with a circular Fermi surface. This super-geometric focusing can be\nquantitatively predicted for arbitrary device geometry, based on the hexagonal\ncyclotron orbits appearing in this material. These results suggest a novel\nclass of ballistic electronic devices exploiting the unique transport\ncharacteristics of strongly faceted Fermi surfaces.",
        "positive": "Quantum Spin-quantum Anomalous Hall Effect with Tunable Edge States in\n  Sb Monolayer-based Heterostructures: A novel topological insulator with tunable edge states, called quantum\nspin-quantum anomalous Hall (QSQAH) insulator, is predicted in a\nheterostructure of a hydrogenated Sb (SbH) monolayer on a LaFeO3 substrate by\nusing ab initio methods. The substrate induces a drastic staggered exchange\nfield in the SbH film, which plays an important role to generate the QSQAH\neffect. A topologically nontrivial band gap (up to 35 meV) is opened by Rashba\nspin-orbit coupling, which can be enlarged by strain and electric field. To\nunderstand the underlying physical mechanism of the QSQAH effect, a\ntight-binding model based on px and py orbitals is constructed. With the model,\nthe exotic behaviors of the edge states in the heterostructure are\ninvestigated. Dissipationless chiral charge edge states related to one valley\nare found to emerge along the both sides of the sample, while low-dissipation\nspin edge states related to the other valley flow only along one side of the\nsample. These edge states can be tuned flexibly by polarization-sensitive\nphotoluminescence controls and/or chemical edge modifications. Such flexible\nmanipulations of the charge, spin, and valley degrees of freedom provide a\npromising route towards applications in electronics, spintronics, and\nvalleytronics."
    },
    {
        "anchor": "Virtual Synthesis of Nanoscale Systems with Pre-Designed Properties:\n  Fundamentals and Applications. Chapter 7. Nickel Oxide Quantum Dots and\n  Polymer Nanowires: The virtual (i.e., fundamental many body quantum theory-based, computational)\nsynthesis method is used to establish electronic templates of about 30\nnon-stoichiometric nanosystems composed of nickel and oxygen atoms and ranging\nfrom about 6 {\\AA} to 6 nm in linear dimensions. Flexible and stretchable Ni-O\nbond in such structures accommodates various ratios of Ni to O atoms, and both\nantiferromagnetic and ferromagnetic spin alignments. Depending on synthesis\nconditions, smaller Ni-O quantum dots (QDs) composed of up to 14 atoms or so\nmay have both types of spin alignments, while quantum-confined, quasi one\ndimensional Ni-O nanowires (QWs) appear to be nanopolymers with\nantiferromagnetic spin alignment. Ni-O bond flexibility and related ease of\nspin re-arrangement may facilitate physical mechanisms leading to the\ndevelopment or loss of exchange bias when such Ni-O quantum dots and wires\n(QDWs) interact with surfaces or each other at some thermochemical conditions.\nThese structural and compositional flexibility is reflected by QDWs' molecular\nelectrostatic potential (MEP) and electronic level structure (ELS). In\nparticular, the direct optical transition energy (OTE) of the studied Ni-O\nsystems may vary within an order of magnitude, and their electronic and\nmagnetic properties can be finely tuned to match applications requirements by\nmanipulations with synthesis conditions, the structure and composition of\nquantum confinement. The developed electronic templates are available upon\nrequest.",
        "positive": "Structural, electronic and optical properties of well-known primary\n  explosive: Mercury fulminate: Mercury Fulminate (MF) is one of the well-known primary explosives since 17th\ncentury and it has rendered invaluable service over many years. However, the\ncorrect molecular and crystal structures are determined recently after 300\nyears of its discovery. In the present study, we report pressure dependent\nstructural, elastic, electronic and optical properties of MF. Non-local\ncorrection methods have been employed to capture the weak van der Waals\ninteractions in layered and molecular energetic MF. Among the non-local\ncorrection methods tested, optB88-vdW method works well for the investigated\ncompound. The obtained equilibrium bulk modulus reveals that MF is softer than\nthe well known primary explosives Silver Fulminate (SF), silver azide and lead\nazide. MF exhibits anisotropic compressibility (b>a>c) under pressure,\nconsequently the corresponding elastic moduli decrease in the following order:\nC22>C11>C33. The structural and mechanical properties suggest that MF is more\nsensitive to detonate along c-axis (similar to RDX) due to high compressibility\nof Hg...O non-bonded interactions along that axis. Electronic structure and\noptical properties were calculated including spin-orbit (SO) interactions using\nfull potential linearized augmented plane wave method within recently developed\nTran-Blaha modified Becke-Johnson (TB-mBJ) potential. The calculated TB-mBJ\nelectronic structures of SF and MF show that these compounds are indirect\nbandgap insulators. Also, SO coupling is found to be more pronounced for 4d and\n5d-states of Ag and Hg atoms of SF and MF, respectively. Partial density of\nstates and electron charge density maps were used to describe the nature of\nchemical bonding. Ag-C bond is more directional than Hg-C bond which makes SF\nto be more unstable than MF. The effect of SO coupling on optical properties\nhas also been studied and found to be significant for both of the compounds."
    },
    {
        "anchor": "Influence of gas ambient on charge writing at the LaAlO3/SrTiO3\n  heterointerface: We investigated the influences charge writing on the surface work function\nand resistance of the LaAlO3/SrTiO3 (LAO/STO) heterointerface in several gas\nenvironments (air, O2, N2, and H2/N2). Charge writing decreased the surface\nwork function and resistance of the LAO/STO sample quite a lot in air but\nslightly in O2.The interface carrier density was extracted from the measured\nsheet resistance and compared with that obtained from the proposed\ncharge-writing mechanisms, such as carrier transfer via surface adsorbates and\nsurface redox. Such quantitative analyses suggested that additional processes\n(e.g., electronic state modification and electrochemical surface reaction) were\nrequired to explain charge writing on the LAO/STO interface.",
        "positive": "High-temperature cyclic oxidation kinetics and microstructural\n  transition mechanisms of Ti-6Al-4V composites reinforced with hybrid\n  (TiC+TiB) networks: The microstructural features and high-temperature oxidation resistance of\nhybrid (TiC+TiB) networks reinforced Ti-6Al-4V composites were investigated\nafter fabricated with reaction hot pressing technique. The inhomogeneous\ndistribution of hybrid reinforcers resulted in a sort of stress-induced grain\nrefinement for {\\alpha}-Ti matrix phase, which was further facilitated by\nheterogeneous nucleation upon additive interfaces. HRTEM analyses revealed the\ncrystallographic orientation relation between TiB and alpha-Ti phases as\n(201)TiB//(-1100)alpha-Ti plus [11-2]//[0001] alpha-Ti, while TiC and\n{\\alpha}-Ti phases maintained the interrelation of (-200)TiC//(-2110)\n{\\alpha}-Ti and [001]TiC//[01-10] alpha-Ti. The hybridly reinforced\nTi-6Al-4V/(TiC+TiB) composites displayed superior oxidation resistance to both\nthe sintered matrix alloy and the two composites reinforced solely with TiC or\nTiB addition during the cyclic oxidation at 873, 973 and 1073 K respectively\nfor 100 h. The hybrid reinforcers volume fraction was a more influential factor\nto improve oxidation resistance than the matrix alloy powder size. As\ntemperature rose from 873 to 1073 K, the oxidation kinetics transferred from\nthe nearly parabolic type through qusilinear tendency into the finally linear\nmode. This corresponded to the morphological transition of oxide scales from a\ncontinuous protective film to a partially damaged layer and ended up with the\ncomplete spallation of alternating alumina and rutile multilayers. A\nphenomenological model was proposed to elucidate the growth process of oxides\nscales. The release of thermal stress, the suppression of oxygen diffusion and\nthe fastening of oxide adherence were found as the three major mechanisms to\nenhance the oxidation resistance of hybrid reinforced composites."
    },
    {
        "anchor": "Effective permittivity of random plasmonic composites: An effective-medium theory (EMT) is developed to predict the effective\npermittivity \\epsilon_eff of dense random dispersions of high\noptical-conductivity metals such as Ag, Au and Cu. Dependence of \\epsilon_eff\non the volume fraction \\phi, a microstructure parameter \\kappa related to the\nstatic structure factor and particle radius a is studied. In the electrostatic\nlimit, the upper and lower bounds of \\kappa correspond to Maxwell-Garnett and\nBruggeman EMTs respectively. Finite size effects are significant when\n|\\beta^2(ka/n)^3| becomes O(1) where \\beta, k, and n denote the nanoparticle\npolarizability, wavenumber and matrix refractive index respectively. The\ncoupling between the particle and effective medium results in a red-shift in\nthe resonance peak, a non-linear dependence of \\epsilon_eff on \\phi, and Fano\nresonance in \\epsilon_eff.",
        "positive": "Nano-sheets of two-dimensional polymers with dinuclear (arene)ruthenium\n  nodes, synthesised at a liquid/liquid interface: We developed a new class of mono- or few-layered two-dimensional polymers\nbased on dinuclear (arene)ruthenium nodes, obtained by combining the imine\ncondensation with an interfacial chemistry process, and use a modified\nLangmuir-Schaefer method to transfer them onto solid surfaces. Robust\nnano-sheets of 2D polymers including dinuclear complexes of heavy ruthenium\natoms as nodes were synthesised. These nano-sheets, whose thickness is of a few\ntens of nanometers, were suspended onto solid porous membranes. Then, they were\nthoroughly characterised with a combination of local probes, including Raman\nscattering, Fourier transform infrared spectroscopy and transmission electron\nmicroscopy in imaging and diffraction mode."
    },
    {
        "anchor": "Reversible Structural Transition of Two-Dimensional Copper Selenide on\n  Cu(111): Structural engineering opens a door to manipulating the structures and thus\ntuning the properties of two-dimensional materials. Here, we report a\nreversible structural transition in honeycomb CuSe monolayer on Cu(111) through\nscanning tunneling microscopy (STM) and Auger electron spectroscopy (AES).\nDirect selenization of Cu(111) gives rise to the formation of honeycomb CuSe\nmonolayers with 1D moir\\'e structures (stripe-CuSe), due to the asymmetric\nlattice distortions in CuSe induced by the lattice mismatch. Additional\ndeposition of Se combined with post annealing results in the formation of\nhoneycomb CuSe with quasi-ordered arrays of triangular holes (hole-CuSe),\nnamely, the structural transition from stripe-CuSe to hole-CuSe. Further,\nannealing the hole-CuSe at higher temperature leads to the reverse structural\ntransition, namely from hole-CuSe to stripe-CuSe. AES measurement unravels the\nSe content change in the reversible structural transition. Therefore, both the\nSe coverage and annealing temperature play significant roles in the reversible\nstructural transition in CuSe on Cu(111). Our work provides insights in\nunderstanding of the structural transitions in 2D materials.",
        "positive": "The effect of atomic-scale defects and dopants on graphene electronic\n  structure: Graphene, being one-atom thick, is extremely sensitive to the presence of\nadsorbed atoms and molecules and, more generally, to defects such as vacancies,\nholes and/or substitutional dopants. This property, apart from being directly\nusable in molecular sensor devices, can also be employed to tune graphene\nelectronic properties. Here we briefly review the basic features of\natomic-scale defects that can be useful for material design. After a brief\nintroduction on isolated $p_z$ defects, we analyse the electronic structure of\nmultiple defective graphene substrates, and show how to predict the presence of\nmicroscopically ordered magnetic structures. Subsequently, we analyse the more\ncomplicated situation where the electronic structure, as modified by the\npresence of some defects, affects chemical reactivity of the substrate towards\nadsorption (chemisorption) of atomic/molecular species, leading to preferential\nsticking on specific lattice positions. Then, we consider the reverse problem,\nthat is how to use defects to engineer graphene electronic properties. In this\ncontext, we show that arranging defects to form honeycomb-shaped superlattices\n(what we may call \"supergraphenes\") a sizeable gap opens in the band structure\nand new Dirac cones are created right close to the gapped region. Similarly, we\nshow that substitutional dopants such as group IIIA/VA elements may have gapped\nquasi-conical structures corresponding to massive Dirac carriers. All these\npossible structures might find important technological applications in the\ndevelopment of graphene-based logic transistors."
    },
    {
        "anchor": "Surface sensitivity of the spin Seebeck effect: We have investigated the influence of the interface quality on the spin\nSeebeck effect (SSE) of the bilayer system yttrium iron garnet (YIG) - platinum\n(Pt). The magnitude and shape of the SSE is strongly influenced by mechanical\ntreatment of the YIG single crystal surface. We observe that the saturation\nmagnetic field H_{sat} for the SSE signal increases from 55.3 mT to 72.8 mT\nwith mechanical treatment. The change in the magnitude of H_{sat} can be\nattributed to the presence of a perpendicular magnetic anisotropy due to the\ntreatment induced surface strain or shape anisotropy in the Pt/YIG system. Our\nresults show that the SSE is a powerful tool to investigate magnetic anisotropy\nat the interface.",
        "positive": "Thermoelectric Properties of Ho-doped Bi1-xSbx: The Seebeck coefficients, electrical resistivities, total thermal\nconductivities, and magnetization are reported for temperatures between 5 and\n350 K for n-type Bi0.88Sb0.12 nano-composite alloys made by Ho-doping at the 0,\n1 and 3% atomic levels. The alloys were prepared using a dc hot-pressing\nmethod, and are shown to be single phase for both Ho contents with grain sizes\non the average of 900 nm. We find the parent compound has a maximum of ZT =\n0.28 at 231 K, while doping 1% Ho increases the maximum ZT to 0.31 at 221 K and\nthe 3% doped sample suppresses the maximum ZT = 0.24 at a temperature of 260 K."
    },
    {
        "anchor": "Rare earth engineering in RMn$_6$Sn$_6$ topological kagome magnets: Exploration of the topological quantum materials with electron correlation is\nat the frontier of physics, as the strong interaction may give rise to new\ntopological phases and transitions. Here we report that a family of kagome\nmagnets RMn$_6$Sn$_6$ manifest the quantum transport properties analogical to\nthose in the quantum-limit Chern magnet TbMn$_6$Sn$_6$. The topological\ntransport in the family, including quantum oscillations with nontrivial Berry\nphase and large anomalous Hall effect arising from Berry curvature field,\npoints to the existence of massive Dirac fermions. Our observation demonstrates\na close relationship between rare-earth magnetism and topological electron\nstructure, indicating the rare-earth elements can effectively engineer the\nChern quantum phase in kagome magnets.",
        "positive": "The role of nitrogen related defects in high-k dielectric oxides:\n  Density functional studies: Using ab initio density functional total energy and molecular dynamics\nsimulations, we study the effects of various forms of nitrogen post deposition\nanneal (PDA) on the electric properties of hafnia in the context of its\napplication as a gate dielectric in field effect transistors (FET). We consider\nthe atomic structure and energetics of nitrogen containing defects which can be\nformed during the PDA in various N-based ambients: N2, N+2, N, NH3, NO, N2O. We\nanalyse the role of such defects in fixed charge accumulation, electron\ntrapping and in the growth of the interface SiOx layer. We find that nitrogen\nanneal of the oxides leads to an effective immobilization of native defects\nsuch as oxygen vacancies and interstitial oxygen ions, which may inhibit growth\nof silica layer. Nitrogen in any form effectively incorporates into the\npre-existing oxygen vacancies and, therefore may decrease the concentration of\nshallow electron traps. However, nitrogen in any form is unlikely to\nsignificantly reduce the fixed charge in the dielectric."
    },
    {
        "anchor": "119Sn NMR probe of magnetic fluctuations in SnO2 nanoparticles: 119Sn nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation\nrate (1/T1) in SnO2 nanoparticles were measured as a function of temperature\nand compared with those of SnO2 bulk sample. A 15% loss of 119Sn NMR signal\nintensity for the nano sample compared to the bulk sample was observed. This is\nindicative of ferromagnetism from a small fraction of the sample. Another major\nfinding is that the recovery of the 119Sn longitudinal nuclear magnetization in\nthe nano sample follows a stretched exponential behavior, as opposed to that in\nbulk which is exponential. Further, the 119Sn 1/T1 at room temperature is found\nto be much higher for the nano sample than for its bulk counterpart. These\nresults indicate the presence of magnetic fluctuations in SnO2 nanoparticles in\ncontrast to the bulk (non-nano) which is diamagnetic. These local moments could\narise from surface defects in the nanoparticles.",
        "positive": "Neutron Reflectometry: a technique for revealing emergent phenomena at\n  interfaces in heterostructures: Neutron reflectometry (NR) has emerged as a unique technique for the\ninvestigation of structure and magnetism of thin films of both biologically\nrelevant and magnetic materials. The advantage of NR with respect to many other\nsurface-sensitive techniques is its sub-nanometer resolution that enables\nstructural characterizations at the molecular level. While in the case of\nbio-relevant samples, NR can be used to probe thin films at buried interfaces,\nnon-destructively, even adopting a complex sample environment. Whereas the\npolarized version of NR is best suited for revealing the interface magnetism\nwith a sub-nanometer depth resolution. In this article, I will briefly describe\nthe basic principle of NR with some applications of NR to both bio-relevant\nsamples and magnetic heterostructures."
    },
    {
        "anchor": "Interlayer Resistance of Misoriented MoS2: Interlayer misorientation in transition metal dichalcogenides alters the\ninterlayer distance, the electronic band structure, and the vibrational modes,\nbut, its effect on the interlayer resistance is not known. This work analyzes\nthe coherent interlayer resistance of misoriented 2H-MoS2 for low energy\nelectrons and holes as a function of the misorientation angle. The electronic\ninterlayer resistance monotonically increases with the supercell lattice\nconstant by several orders of magnitude similar to that of misoriented bilayer\ngraphene. The large hole coupling gives low interlayer hole resistance that\nweakly depends on the misorientation angle. Interlayer rotation between an\nn-type region and a p-type region will suppress the electron current with\nlittle effect on the hole current. We estimate numerical bounds and explain the\nresults in terms of the orbital composition of the bands at high symmetry\npoints. Density functional theory calculations provide the interlayer coupling\nused in both a tunneling Hamiltonian and a non-equilibrium Green function\ncalculation of the resistivity.",
        "positive": "Corollary to the Hohenberg-Kohn Theorem: In this paper we construct such a set of `degenerate' Hamiltonians $\\hat{H}$,\nwhich differ by an `intrinsic' constant but represent different physical\nsystems yet possess the same ground state density. . Thus, although the proof\nof Hohenberg-Kohn (HK) theorem is independent of whether the constant $C$ is\nadditive or intrinsic, its applicability is restricted to excluding the case of\nthe latter. This constitutes the corollary to the theorem.The corollary has\nalso been extended to the time-dependent version of the HK theorem."
    },
    {
        "anchor": "Experimental and First principle calculation of Co_xNi_{(1-x)}Si solid\n  solution structural stability: We report the investigation of the structural stability of\nCo$_{(1-x)}$Ni$_x$Si monosilicides for $0<x<1$. As CoSi crystallizes in the\nFeSi-type structure (B20) and NiSi is stable in the MnP-type structure (B31), a\ncomplete set of samples has been synthesized and a systematic study of phase\nformation under different annealing conditions were carried out in order to\nunderstand the reason of such a structural transition when x goes from 0 to 1.\nThis study has revealed a limit in the solubility of Ni in CoSi B20 structure\nof about 17.5 at.% and of Co in NiSi B31 phase of about 13 at.%. For\n$0.35<x<0.74$ both B20 and B31 phases are present in the sample at there\nrespective limits of solubility. The temperature dependence of the magnetic\nsusceptibility has also been measured revealing diamagnetic behaviors. Optimal\nstructural parameters and phase stability of the solid solution have been\ninvestigated using self-consistent full-potential linearized augmented plane\nwave method (FP-LAPW) based on the density functional theory (DFT). This\ncalculation well predicts the structural instability observed experimentally.",
        "positive": "Spin-density functional theories and their $+U$ and $+J$ extensions: a\n  comparative study of transition metals and transition metal oxides: Previous work on the physical content of exchange correlation functionals\nthat depend on both charge and spin densities is extended to elemental\ntransition metals and a wider range of perovskite transition metal oxides. A\ncomparison of spectra and magnetic moments calculated using exchange\ncorrelation functionals depending on charge density only or on both charge and\nspin densities, as well as the $+U$ and $+J$ extensions of these methods\nconfirms previous conclusions that the spin-dependent part of the exchange\ncorrelation functional provides an effective Hund's interaction acting on the\ntransition metal $d$ orbitals. For the local spin density approximation and\nspin-dependent Perdew-Burke-Ernzerhof generalized gradient approximation, the\neffective Hund's exchange is found to be larger than 1 eV. The results indicate\nthat at least as far as applications to transition metals and their oxides are\nconcerned, $+U$, $+J$ and +dynamical mean field theory extensions of density\nfunctional theory should be based on exchange-correlation functionals of charge\ndensity only."
    },
    {
        "anchor": "Linear and nonlinear optical probe of the ferroelectric-like phase\n  transition in a polar metal, LiOsO3: LiOsO3 is one of the first materials identified in a recent literature as a\n'polar metal', a class of materials that are simultaneously noncentrosymmetric\nand metallic. In this work, the linear and nonlinear optical susceptibility of\nLiOsO3 is studied by means of ellipsometry and optical second harmonic\ngeneration (SHG). Strong optical birefringence is observed using spectroscopic\nellipsometry. The nonlinear optical susceptibility extracted from SHG\npolarimetry reveals that the tensor components are of the same magnitude as in\nisostructural insulator LiNbO3, except the component along the polar axis d33,\nwhich is suppressed by an order of magnitude. Temperature-dependent SHG\nmeasurements in combination with Raman spectroscopy indicate a continuous\norder-disorder type polar phase transition at 140 K. Linear and nonlinear\noptical microscopy techniques reveal 109 deg/71 deg ferroelastic domain walls,\nlike in other trigonal ferroelectrics. No 180 deg polar domain walls are\nobserved to emerge across the phase transition.",
        "positive": "Bending, Nanoindentation and Plasticity Noise in FCC single and poly\n  crystals: We present a high-throughput nanoindentation study of in-situ bending effects\non incipient plastic deformation behavior of polycrystalline and\nsingle-crystalline pure aluminum and pure copper at ultra-nano depths (<200nm).\nWe find that hardness displays a statistically inverse dependence on in-plane\nstress for indentation depths smaller than 10nm, and the dependence disappears\nfor larger indentation depths. In addition, plastic noise in the\nnanoindentation force and displacement displays statistically robust noise\nfeatures, independently of applied stresses. Our experimental results suggest\nthe existence of a regime in FCC crystals where ultra-nano hardness is\nsensitive to residual applied stresses, but plasticity pop-in noise is\ninsensitive to it."
    },
    {
        "anchor": "Enhanced UV Light emission from Silicon nanoparticles induced by Au ion\n  implantation: Study of light emitting silicon fabricated by ion implantation.",
        "positive": "Photo-oxidation of Graphene in the Presence of Water: Oxygen molecules are found to exhibit non-negligible reactivity with graphene\nunder strong light irradiation in the presence of water. The reaction is\ntriggered by the laser Raman spectroscopy measurement itself, and the D band\n(ca. 1340 cm-1) becomes larger as the laser irradiation is prolonged. The\nelectronic transport properties of the graphene derivative are also\ninvestigated and both the electron and hole mobility are found to be reduced.\nThese results are attributed to oxidation of graphene. This primitive\nmodification method can be exploited to manipulate the structural and\nelectronic properties of graphene."
    },
    {
        "anchor": "3D versus 2D domain wall interaction in ideal and rough nanowires: The interaction between transverse magnetic domain walls (TDWs) in planar\n(2D) and cylindrical (3D) nanowires is examined using micromagnetic\nsimulations. We show that in perfect and surface deformed wires the free TDWs\nbehave differently, as the 3D TDWs combine into metastable states with average\nlifetimes of 300ns depending on roughness, while the 2D TDWs do not due to 2D\nshape anisotropy. When the 2D and 3D TDWs are pinned at artificial\nconstrictions, they behave similarly as they interact mainly through the\ndipolar field. This magnetostatic interaction is well described by the point\ncharge model with multipole expansion. In surface deformed wires with\nartificial constrictions, the interaction becomes more complex as the depinning\nfield decreases and dynamical pinning can lead to local resonances. This can\nstrongly influence the control of TDWs in DW-based devices.",
        "positive": "Current-excited magnetization dynamics in narrow ferromagnetic wires: We investigate the current-excited magnetization dynamics in a narrow\nferromagnetic Permalloy wire by means of Lorentz microscopy, together with the\nresults of simultaneous transport measurements. A detailed structural evolution\nof the magnetization is presented as a function of the applied current density.\nLocal structural deformation, bidirectional displacement, and magnetization\nreversal are found below the Curie temperature with increasing the current\ndensity. We discuss probable mechanisms of observed features of the\ncurrent-excited magnetization dynamics."
    },
    {
        "anchor": "Strong In-plane Anisotropy in the Electronic Properties of Doped\n  Transition Metal Dichalcogenides exhibited in W1-xNbxS2: In this work, we study the electronic properties of monolayer transition\nmetal dichalcogenide materials subjected to aliovalent doping, using Nb-doped\nWS2 as an exemplar. Scanning transmission electron microscopy imaging of the\nas-grown samples reveals an anisotropic Nb dopant distribution, prompting our\ninvestigation of anisotropy in electronic properties. Through electronic\nstructure calculations on supercells representative of observed structures, we\nconfirm that local Nb-atom distributions are consistent with energetic\nconsiderations, although kinetic processes occurring during sample growth must\nbe invoked to explain the overall symmetry-breaking. We perform effective\nbandstructure and conductivity calculations on realistic models of the material\nthat demonstrate that a high level of anisotropy can be expected in electronic\nproperties including conductivity and mobility.",
        "positive": "Extreme magnetoresistance induced by Zeeman effect-driven electron-hole\n  compensation and topological protection in MoSi$_2$: The magnetoresistance is the magnetic field induced change of electrical\nresistivity of a material. Recent studies have revealed extremely large\nmagnetoresistance in several non-magnetic semimetals, which has been explained\non the basis of either electron-hole compensation or the Fermi surface\ntopology, or the combination of both. Here, we present a single crystal study\non MoSi$_2$, which exhibits extremely large magnetoresistance, approaching\nalmost 10$^7$ % at 2 K and 14 T magnetic field. It is found that the\nelectron-hole compensation level in MoSi$_2$ evolves with magnetic field, which\nis resulted from strong Zeeman effect, and found beneficial in boosting the\nlarge non-saturating magnetoresistance. The non-trivial Berry phase in the de\nHaas-van Alphen oscillations and the moderate suppression of backward\nscattering of the charge carriers lend support for the topological nature of\nthis semimetal. The ultra-large carrier mobility of the topologically protected\ncharge carriers reinforces the magnetoresistance of MoSi2 to an unprecedented\nlarge value."
    },
    {
        "anchor": "Defects of Ge quantum dot arrays on the Si(001) surface: Defects of Ge quantum dot arrays may affect the electrophysical,\nphotoelectrical or optical properties of Ge/Si heterostructures as well as the\nfunctionality of devices produced on their basis. The defects of Ge quantum dot\narrays formed at moderate temperatures on the Si(001) surface have been\ninvestigated by the ultra high vacuum scanning tunnelling microscope integrated\nwith the molecular beam epitaxy chamber. A preliminary classification of the\ndefects has been carried out. Morphological peculiarities of the defects have\nbeen studied. The surface densities of defects of different types have been\ndetermined.",
        "positive": "Mechanical, thermal and optical properties of perovskite borides RRh3B(R\n  = Y, Zr, and Nb): We report here ab initio density functional theory (DFT) calculations of\nstructural, elastic, Peierls stress, thermodynamic and optical properties of\nRRh3B (R = Y, Zr and Nb) using the plane wave psedudopotential method. The\nmaterials possess better ductile behavior in comparison with a selection of\nlayered MAX phases but the anisotropy is strong, particularly in NbRh3B. The\nPeierls stress, approximately 3-4 times larger than in MAX phases, show that\ndislocation movement may follow but with much reduced occurrences compared to\nMAX phases. The temperature and pressure dependence of bulk modulus, specific\nheats, thermal expansion coefficient, and Debye temperature are calculated for\nthe first time for two of the three compounds using the quasi-harmonic Debye\nmodel with phononic effects for elevated temperature and pressure. The obtained\nresults are discussed in comparison to the behavior of other related compounds.\nFurther the features of optical functions obtained for the first time are\ndiscussed. The study reveals that the reflectivity is high in the IR-UV regions\nup to ~ 17.5 eV (YRh3B, ZrRh3B) and 20 eV (NbRh3B), thus showing promise as\ngood coating materials.\n  Keywords: RRh3B; Quasi-harmonic Debye model; Thermodynamic properties;\nOptical properties"
    },
    {
        "anchor": "Convergence method for calculating solutions to the 3D invariant\n  embedding integro-differential equations describing electron transport\n  processes: The electron and photon transport processes in spectroscopy techniques\ndescribed by the invariant embedding theory is here revisited. We report a\nconvergence method to obtain closed analytical solutions to the 3D\nintegro-differential equations. This method was successfully used in\ncalculating the dependence of the electron backscattered fraction on the atomic\nnumber and on the energy. Also the fraction of absorbed electron as a function\nof incident angles was calculated. Using a states ladder model for the electron\nenergies, this method provides a tool for testing physical parameters involved\nin the transport theory, such as the elastic and inelastic cross sections. The\noutstanding feature of the invariant embedding differential equations of\nconsidering observable quantities (such as the emergent flux of particles) as\nindependent variables makes them a suitable tool to describe experimental\nsituations.",
        "positive": "Synthesis and characterization of Na03RhO206H2O - a semiconductor with a\n  weak ferromagnetic component: We have prepared the oxyhydrate Na03RhO206H2O by extracting Na+ cations from\nNaRhO2 and intercalating water molecules using an aqueous solution of Na2S2O8.\nSynchrotron X-ray powder diffraction, thermogravimetric analysis (TGA), and\nenergy-dispersive x-ray analysis (EDX) reveal that a non-stoichiometric\nNa03(H2O)06 network separates layers of edge-sharing RhO6 octahedra containing\nRh3+(4d6, S=0) and Rh4+ (4d5, S=1/2). The resistivities of NaRhO2 and\nNa03RhO206H2O (T < 300) reveal insulating and semi-conducting behavior with\nactivation gaps of 134 meV and 7.8 meV, respectively. Both Na03RhO206H2O and\nNaRhO2 show paramagnetism at room temperature, however, the sodium-deficient\nsample exhibits simultaneously a weak but experimentally reproducible\nferromagnetic component. Both samples exhibit a temperature-independent Pauli\nparamagnetism, for NaRhO2 at T > 50 K and for Na03RhO206H2O at T > 25 K. The\nrelative magnitudes of the temperature-independent magnetic susceptibilities,\nthat of the oxide sample being half that of the oxyhydrate, is consistent with\na higher density of thermally accessible electron states at the Fermi level in\nthe hydrated sample. At low temperatures the magnetic moments rise sharply,\nproviding evidence of localized and weakl -ordered electronic spins."
    },
    {
        "anchor": "Control of magnetism in bilayer CrI$_{3}$ by an external electric field: Recently intrinsic ferromagnetism in two-dimensional(2D) van der Waals\nmaterials was discovered [1, 2, 3]. A monolayer of Chromiun triiodide(CrI3) is\nferromagnetic while a bilayer structure was reported to be anti-ferro magnetic,\nmoreover an external electric field changes its magnetic phase [4]. We have\nstudied the two found in nature stackings of CrI3 bilayers and found that\nindeed the magnetic phase of one of them can be tuned by an external electric\nfield while the other remains ferromagnetic. We simulate those results with ab\ninitio calculations and explain them with a simple model based on a rigid shift\nof the bands associated with different spins. The model can be applied to\nsimilar van der Waal stacked insulating bilayer anti-ferromagnets.",
        "positive": "Highly efficient and transferable interatomic potentials for\n  \u03b1-iron and \u03b1-iron/hydrogen binary systems using deep neural\n  networks: Artificial neural network potentials (NNPs) have emerged as effective tools\nfor understanding atomic interactions at the atomic scale in various phenomena.\nRecently, we developed highly transferable NNPs for {\\alpha}-iron and\n{\\alpha}-iron/hydrogen binary systems (Physical Review Materials 5 (11),\n113606, 2021). These potentials allowed us to investigate deformation and\nfracture in {\\alpha}-iron under the influence of hydrogen. However, the\ncomputational cost of the NNP remains relatively high compared to empirical\npotentials, limiting their applicability in addressing practical issues related\nto hydrogen embrittlement. In this work, building upon our prior research on\niron-hydrogen NNP, we developed a new NNP that not only maintains the excellent\ntransferability but also significantly improves computational efficiency (more\nthan 40 times faster). We applied this new NNP to study the impact of hydrogen\non the cracking of iron and the deformation of polycrystalline iron. We\nemployed large-scale through-thickness {110}<110> crack models and large-scale\npolycrystalline {\\alpha}-iron models. The results clearly show that hydrogen\natoms segregated at crack tips promote brittle-cleavage failure followed by\ncrack growth. Additionally, hydrogen atoms at grain boundaries facilitate the\nnucleation of intergranular nanovoids and subsequent intergranular fracture. We\nanticipate that this high-efficiency NNP will serve as a valuable tool for\ngaining atomic-scale insights into hydrogen embrittlement."
    },
    {
        "anchor": "Ultrafast formation of transient 2D diamond-like structure in twisted\n  bilayer graphene: Due to the absence of matching carbon atoms at honeycomb centers with carbon\natoms in adjacent graphene sheets, theorists predicted that a sliding process\nis needed to form AA, AB, or ABC stacking when directly converting graphite\ninto sp3 bonded diamond. Here, using twisted bilayer graphene, which naturally\nprovides AA and AB stacking configurations, we report the ultrafast formation\nof a transient 2D diamond-like structure (which is not observed in aligned\ngraphene) under femtosecond laser irradiation. This photo-induced phase\ntransition is evidenced by the appearance of new bond lengths of 1.94A and\n3.14A in the time-dependent differential pair distribution function using MeV\nultrafast electron diffraction. Molecular dynamics and first principles\ncalculation indicate that sp3 bonds nucleate at AA and AB stacked areas in\nmoire pattern. This work sheds light on the direct graphite-to-diamond\ntransformation mechanism, which has not been fully understood for more than 60\nyears.",
        "positive": "Numerical calculation of magnetic form factors of complex shape\n  nano-particles coupled with micromagnetic simulations: We investigate the calculation of the magnetic form factors of nano-objects\nwith complex geometrical shapes and non homogeneous magnetization\ndistributions. We describe a numerical procedure which allows to calculate the\n3D magnetic form factor of nano-objects from realistic magnetization\ndistributions obtained by micromagnetic calculations. This is illustrated in\nthe canonical cases of spheres, rods and platelets. This work is a first step\ntowards a 3D vectorial reconstruction of the magnetization at the nanometric\nscale using neutron scattering techniques."
    },
    {
        "anchor": "CaCu_3Ti_4O_12/CaTiO_3 Composite Dielectrics: A Ba/Pb-free Ceramics with\n  High Dielectric Constants: We have measured dielectric properties of Ca$_{1+x}$Cu$_{3-x}$Ti$_4$O$_{12}$\n($x$ = 0, 0.1, 0.5, 1, 1.5, 2, 2.9 and 3), and have found that\nCa$_2$Cu$_2$Ti$_4$O$_{12}$ (a composite of CaCu$_3$Ti$_4$O$_{12}$ and\nCaTiO$_3$) exhibits a high dielectric constant of 1800 with a low dissipation\nfactor of 0.02 below 100 kHz from 220 to 300 K. These are comparable to (or\neven better than) those of the Pb/Ba-based ceramics, which could be attributed\nto a barrier layer of CaTiO$_3$ on the surface of the CaCu$_3$Ti$_4$O$_{12}$\ngrains. The composite dielectric ceramics reported here are environmentally\nbenign as they do not contain Ba/Pb.",
        "positive": "Negative scattering asymmetry parameter for dipolar particles: Unusual\n  reduction of the transport mean free path and radiation pressure: We establish a relationship between the electric magnetic dipole interaction\nforce from a plane wave on a small magnetodielectric particle, the transport\ncross-section and the scattering asymmetry parameter, g. In this way, we\npredict negative g that minimize the transport mean free-path below values of\nthe scattering mean free path of a dilute suspension of both perfectly\nreflecting spheres as well as of those that satisfy the so-called Kerker\nconditions, like high permittivity dielectric ones."
    },
    {
        "anchor": "Extended scheme for the projection of material tensors of arbitrary\n  symmetry onto a higher symmetry tensor: I propose a straightforward generalization of the projection scheme for\nelastic tensors introduced by Moakher and Norris [J. Elasticity 85, 215 (2006)]\nthat takes into account also rotations. The \"closest\" tensor of any desired\nsymmetry to the original tensor of lower symmetry is \"closer\" in this\ngeneralized scheme. The method has an important application in the context of\nthe special quasirandom structure (SQS) method for the computational modeling\nof alloys, whereby the supercell's symmetry, and therefore that of the tensors\nrepresenting its properties, is reduced with respect to the material's\nunderlying symmetry. The approach allows to extract the tensor components most\nrepresentative of the macroscopic symmetry of the material. Although the\napproach is general, in the present case I apply it to the elastic tensor and\ngive numerical examples. Simple approximate analytical expressions for cubic\nmaterials are also provided.",
        "positive": "Single-Bubble Sonoluminescence as Dicke Superradiance at Finite\n  Temperature: Sonoluminescence is a process in which a strong sound field is used to\nproduce light in liquids. We explain sonoluminescence as a phase transition\nfrom ordinary fluorescence to a superradiant phase. We consider a spin-boson\nmodel composed of a single bosonic mode and an ensemble of $N$ identical\ntwo-level atoms. We assume that the whole system is in thermal equilibrium with\na reservoir at temperature $\\beta^{-1}$. We show that, in a\nultrastrong-coupling regime, between the two-level atoms and the\nelectromagnetic field it is possible to have a cooperative interaction of the\nmolecules of the gas in the interior of the bubble with the field, generating\nsonoluminescence."
    },
    {
        "anchor": "Anelastic relaxor behavior of Pb(Mg1/3Nb2/3)O3: Elastic storage modulus and loss of relaxor lead magnesium niobate ceramics,\nPb(Mg1/3Nb2/3)O3, have been measured with dynamic mechanical analyzer in single\ncantilever mode in the temperature range from 170 K to 320 K and at frequencies\nfrom 0.1 Hz to 50 Hz. The dependence of the elastic susceptibility (inverse\nmodulus) on temperature and frequency of the driving force has characteristics\nof typical relaxor behavior that can be well described with the Vogel-Fulcher\nlaw. The parameters of the Vogel-Fulcher relation exhibit similar values for\nthe dielectric and anelastic relaxations. Similarities and differences between\nanelastic and dielectric relaxor behaviors are identified.",
        "positive": "Quantum transport in mesoscopic $^3$He films: experimental study of the\n  interference of bulk and boundary scattering: We discuss the mass transport of a degenerate Fermi liquid $^3$He film over a\nrough surface, and the film momentum relaxation time, in the framework of\ntheoretical predictions. In the mesoscopic r\\'egime, the anomalous temperature\ndependence of the relaxation time is explained in terms of the interference\nbetween elastic boundary scattering and inelastic quasiparticle-quasiparticle\nscattering within the film. We exploit a quasiclassical treatment of quantum\nsize effects in the film in which the surface roughness, whose power spectrum\nis experimentally determined, is mapped into an effective disorder potential\nwithin a film of uniform thickness. Confirmation is provided by the\nintroduction of elastic scattering centres within the film. We model further\nstudies on $^3$He confined in nanofluidic sample chambers with lithographically\ndefined surface roughness. The improved understanding of surface roughness\nscattering may impact on enhancing the conductivity in thin metallic films."
    },
    {
        "anchor": "Untangling the role of oxide in Ga-assisted growth of GaAs nanowires on\n  Si substrates: The influence of the oxide in Ga-assisted growth of GaAs nanowires on Si\nsubstrates is investigated. Three different types of oxides with different\nstructure and chemistry are considered. We observe that the critical oxide\nthicknesses needed for achieving nanowire growth depends on the nature of oxide\nand how it is processed. Additionally, we find that different growth conditions\nsuch as temperature and Ga rate are needed for successful nanowire growth on\ndifferent oxides. We generalize the results in terms of the characteristics of\nthe oxides such as surface roughness, stoichiometry and thickness. These\nresults constitute a step further towards the integration of GaAs technology on\nthe Si platform.",
        "positive": "Vibrational and dielectric properties of monolayer transition metal\n  dichalcogenides: First-principles studies of two-dimensional transition metal dichalcogenides\nhave contributed considerably to the understanding of their dielectric,\noptical, elastic, and vibrational properties. The majority of works to date\nfocus on a single material or physical property. Here we use a single\nfirst-principles methodology on the whole family of systems, to investigate in\ndepth the relationships between different physical properties, the underlying\nsymmetry and the composition of these materials, and observe trends. We compare\nto bulk counterparts to show strong interlayer effects in triclinic compounds.\nPreviously unobserved relationships between these monolayer compounds become\napparent. These trends can then be exploited by the materials science,\nnanoscience, and chemistry communities to better design devices and\nheterostructures for specific functionalities."
    },
    {
        "anchor": "A New Approach to the Synthesis of Nanocrystal Conjugated Polymer\n  Composites: A novel one pot process has been developed for the preparation of PbS\nnanocrystals in the conjugated polymer poly 2-methoxy,5-(2\n-ethyl-hexyloxy-p-phenylenevinylene) (MEH-PPV). Current techniques for making\nsuch composite materials rely upon synthesizing the nanocrystals and conducting\npolymer separately, and subsequently mixing them. This multi-step technique has\ntwo serious drawbacks: templating surfactant must be removed before mixing, and\nco-solvent incompatibility causes aggregation. In our method, we eliminate the\nneed for an initial surfactant by using the conducting polymer to terminate and\ntemplate nanocrystal growth. Additionally, the final product is soluble in a\nsingle solvent. We present materials analysis which shows PbS nanocrystals can\nbe grown directly in a conducting polymer, the resulting composite is highly\nordered and nanocrystal size can be controlled.",
        "positive": "Conduction mechanism and switchable photovoltaic effect in (111)\n  oriented BiFe$_{0.95}$Mn$_{0.05}$O$_{3}$ thin film: Epitaxial 200nm BiFe$_{0.95}$Mn$_{0.05}$O$_{3}$ (BFO) film was grown by\npulsed laser deposition on (111) oriented SrTiO3 substrate buffered with a 50nm\nthick SrRuO$_{3}$ electrode. The BFO thin film shows a rhombohedral structure\nand a large remnant polarization of Pr = 104 $\\mu$C/cm$^{2}$. By comparing I(V)\ncharacteristics with different conduction models we reveal the presence of both\nbulk limited Poole-Frenkel and Schottky interface mechanisms and each one\ndominates in a specific range of temperature. At room temperature and under\n10mW laser illumination, the as grown BFO film presents short-circuit current\ndensity (Jsc) and open circuit voltage (Voc) of 2.25mA/cm$^{2}$ and -0.55V\nrespectively. This PV effect can be switched by applying positive voltage\npulses higher than the coercive field. For low temperatures a large Voc value\nof about -4.5V (-225kV/cm) is observed which suggests a bulk\nnon-centrosymmetric origin of the PV response."
    },
    {
        "anchor": "Electrical conduction of Ti/TiOx/Ti structures at low temperatures and\n  high magnetic fields: We present results of electrical conduction studies of Ti/TiOx/Ti planar\nstructures prepared by tip-induced local anodic oxidation (LAO) of titanium\nthin films. The prepared structures have shown almost linear I-V curves at\ntemperatures between 300 K and 30 K, and only slight deviation from linear\nbehaviour at lower temperatures. Electrical conductance of the structures can\nbe adequately explained by a two-channel model where variable range hopping\nchannels and metallic ones coexist in parallel, while a crossover from Mott to\nEfros-Shklovskii variable-range-hopping conductivity has been observed at\ndecreasing temperature. The magnetoresistance of the studied structures is very\nsmall even in magnetic fields up to 9 T. The reported electrical properties of\nthe structures indicate their promising applications as very low heat capacity\ntemperature sensors for cryogenic region and high magnetic fields.",
        "positive": "Intercalation-induced states at the Fermi level and the coupling of\n  intercalated magnetic ions to conducting layers in Ni$_{1/3}$NbS$_2$: The magnetic sublayers introduced by intercalation into the host\ntransition-metal dichalcogenide (TMD) are known to produce various magnetic\nstates. The magnetic sublayers and their magnetic ordering strongly modify the\nelectronic coupling between layers of the host compound. Understanding the\nroots of this variability is a significant challenge. Here we employ the\nangle-resolved photoelectron spectroscopy at various photon energies, the {\\it\nab initio} electronic structure calculations, and modeling to address the\nparticular case of Ni-intercalate, Ni$_{1/3}$NbS$_2$. We find that the bands\naround the Fermi level bear the signature of a strong yet unusual hybridization\nbetween NbS$_2$ conduction band states and the Ni 3$d$ orbitals. The\nhybridization between metallic NbS$_2$ layers is almost entirely suppressed in\nthe central part of the Brillouin zone, including the part of the Fermi surface\naround the $\\mathrm{\\Gamma}$ point. Simultaneously, it gets very pronounced\ntowards the zone edges. It is shown that this behavior is the consequence of\nthe rather exceptional, {\\it symmetry imposed}, spatially strongly varying,\n{\\it zero total} hybridization between relevant Ni magnetic orbitals and the\nneighboring Nb orbitals that constitute the metallic bands. We also report the\npresence of the so-called $\\beta$-feature, discovered only recently in two\nother magnetic intercalates with very different magnetic orderings. In\nNi$_{1/3}$NbS$_2$, the feature shows only at particular photon energies,\nindicating its bulk origin. Common to prior observations, it appears as a\nseries of very shallow electron pockets at the Fermi level, positioned along\nthe edge of the Brillouin zone. Unforeseen by {\\it ab initio} electronic\ncalculations, and its origin still unresolved, the feature appears to be a\nrobust consequence of the intercalation of 2H-NbS$_2$ with magnetic ions."
    },
    {
        "anchor": "First-Principles Approach for Energy Level Alignment at Aqueous\n  Semiconductor Interfaces: A first-principles approach is demonstrated to calculate the relationship\nbetween aqueous semiconductor interface structure and energy level alignment.\nThe physical interface structure is sampled using density functional theory\nbased molecular dynamics, yielding the interface electrostatic dipole. The $GW$\napproach is used to place the electronic band edge energies of the\nsemiconductor relative to the occupied $1b_1$ energy level in water.\nApplication to the specific cases of non-polar $(10\\bar{1}0)$ facets of GaN and\nZnO reveals a significant role for the structural motifs at the interface,\nincluding the degree of interface water dissociation and the dynamical\nfluctuations in the interface Zn-O and O-H bond orientations. These effects\ncontribute up to 0.5 eV.",
        "positive": "Ferromagnetism in Mn Substituted Zirconia: A Density-functional Theory\n  Study: We study the electronic structure and magnetism of 25% Mn substituted cubic\nZirconia (ZrO2) with several homogeneous and heterogeneous doping profiles\nusing density-functional theory calculations. We find that all doping profiles\nshow half-metallic ferromagnetism (HMF), and delta-doping is most energy\nfavorable while homogeneous doping has largest ferromagnetic stabilization\nenergy. Using crystal field theory, we discuss the formation scheme of HMF.\nFinally, we speculate the potential spintronics applications for Mn doped ZrO2,\nespecially as spin direction controllment."
    },
    {
        "anchor": "2D Radial Distribution Function of Silicene: Silicene is the counterpart of graphene and its potential applications as a\npart of the current electronics, based in silicon, make it a very important\nsystem to study. We perform molecular dynamics simulations and analyze the\nstructure of a two dimensional array of Si atoms by means of the radial\ndistribution function, at different temperatures and densities. As a first\napproach, the 2D Lennard-Jones potential is used and two sets of parameters are\ntested. We find that the radial distribution function does not change with the\nparameters and resembles the corresponding to the (111) surface of the FCC\nstructure. The liquid phase appears at very high temperatures, suggesting a\nvery stable system in the solid phase.",
        "positive": "Novel MoSe$_2$-enhanced polyacrylamide composites with tunable\n  refractive index and band gap energy: Hydrogel/inorganic composites have attracted attention in many applications,\nsuch as optoelectronic devices, biosensors, catalysis, and energy storage\nbecause of their capacity to increase and regulate optical and electronic\nfeatures. In this study, MoSe$_2$-enhanced polyacrylamide composites were\nformed using a free radical crosslinking copolymerization process. The UV-vis\nspectrometer was used to investigate the amount-dependent optical properties of\nnew composites. The absorbance, transmittance, band gap energy, extinction\ncoefficient, and refractive index of composites were investigated in detail. It\nhas been found that as the amount of MoSe$_2$ increases, the band gap energy\nvalue decreases, which proves that the material has higher absorption and\nbecomes more conductive. In addition, the optimum amount of MoSe$_2$, which has\na very high optical transmittance in the visible region and also has a high\nconductivity, has been determined. The results reveal that a promising\ncomposite has been produced for many solar energy applications, including\noptoelectronic applications."
    },
    {
        "anchor": "Solid Lubrication with MoS$_2$: A Review: Molybdenum disulfide (MoS$_2$) is one of the most broadly utilized solid\nlubricants with a wide range of applications, including but not limited to\nthose in the aerospace/space industry. Here we present a focused review of\nsolid lubrication with MoS$_2$ by highlighting its structure, synthesis,\napplications and the fundamental mechanisms underlying its lubricative\nproperties, together with a discussion of their environmental and temperature\ndependence. An effort is made to cover the main theoretical and experimental\nstudies that constitute milestones in our scientific understanding. The review\nalso includes an extensive overview of the structure and tribological\nproperties of doped MoS$_2$, followed by a discussion of potential future\nresearch directions.",
        "positive": "Ab initio study of the strain dependence of thermopower in\n  electron-doped SrTiO$_3$: In this paper we explore the different mechanisms that affect the thermopower\nof a band insulating perovskite (in this case, SrTiO$_3$) when subject to\nstrain (both compressive or tensile). We analyze the high temperature, entropy\ndominated limit and the lower temperature, energy-transport regime. We observe\nthat the effect of strain in the high-temperature Seebeck coefficient is small\nat the concentration levels of interest for thermoelectric applications.\nHowever, the effective mass changes substantially with strain, which produces\nan opposite effect to that of the degeneracy-breakups produced by strain. In\nparticular, we find that the thermopower can be enhanced by applying tensile\nstrain in the adequate regime. We conclude that the detrimental effect of\nstrain in thermopower due to band splitting is a minor effect that will not\nhamper the optimization of the thermoelectric properties of oxides with\nt$_{2g}$-active bands by applying strain."
    },
    {
        "anchor": "Magnetism of ordered Sm/Co(0001) surface structures: The epitaxial system Sm/Co(0001) was studied for Sm coverages up to 1\nmonolayer (ML) on top of ultrathin Co/W(110) epitaxial films. Two ordered\nphases were found for 1/3 and 1 ML Sm, respectively. The valence state of Sm\nwas determined by means of photoemission and magnetic properties were measured\nby magneto-optical Kerr effect. We find that 1 ML Sm causes a strong increase\nof the coercivity with respect to that of the underlying 10 ML Co film.\nElement-specific hysteresis loops, measured by using resonant soft x-ray\nreflectivity, show the same magnetic behaviour for the two elements.",
        "positive": "Mechanically exfoliated low-layered [Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$]: A\n  single-crystalline p-type transparent conducting oxide: Transparent conducting oxides (TCOs) are essential components of\noptoelectronic devices and various materials have been explored for highly\nefficient TCOs having a combination of high transmittance and low sheet\nresistance. Here, we focus on a misfit thermoelectric oxide\n[Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$] and fabricate the transparent low-layered\ncrystals by a mechanical tape-peeling method using the single-crystalline\nsamples. From the transmittance measurement, we find that the thickness of\nlow-layered samples is several orders of hundred nanometers, which is\ncomparable with the estimation from the scanning electron microscopy images.\nCompared to the previous results on the polycrystalline and $c$-axis oriented\ntransparent films, the electrical resistivity is reduced owing to the\nsingle-crystalline nature. The figure of merit for the transparent conducting\nmaterials in the present low-layered samples is then evaluated to be higher\nthan the values in the previous reports. The present results on the low-layered\nsingle-crystalline [Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$] may offer a unique class\nof multi-functional transparent thermoelectric oxides."
    },
    {
        "anchor": "Electron spin coherence in metallofullerenes: Y, Sc and La@C82: Endohedral fullerenes encapsulating a spin-active atom or ion within a carbon\ncage offer a route to self-assembled arrays such as spin chains. In the case of\nmetallofullerenes the charge transfer between the atom and the fullerene cage\nhas been thought to limit the electron spin phase coherence time (T2) to the\norder of a few microseconds. We study electron spin relaxation in several\nspecies of metallofullerene as a function of temperature and solvent\nenvironment, yielding a maximum T2 in deuterated o-terphenyl greater than 200\nmicroseconds for Y, Sc and La@C82. The mechanisms governing relaxation (T1, T2)\narise from metal-cage vibrational modes, spin-orbit coupling and the nuclear\nspin environment. The T2 times are over 2 orders of magnitude longer than\npreviously reported and consequently make metallofullerenes of interest in\nareas such as spin-labelling, spintronics and quantum computing.",
        "positive": "Generic bond energy formalism within the modified quasichemical model\n  for ternary solutions: The Modified Quasichemical Model in the Pair Approximation (MQMPA) can\neffectively capture the thermodynamic features of a binary solution with\nShort-Range Ordering (SRO). If the model is used to treat a ternary solution, a\ngeometric interpolation method must be employed to extend the bond energy\nexpression from binary to ternary formalism. The aim of the present work is to\nimplement such extension by means of a generic geometric interpolation\napproach. The generic method is unbiased and can be transformed into the widely\nused Kohler, Toop and Muggianu approaches with special interpolation\nparameters. The interpolation parameters can be calculated by the integration\nmethod as well as be optimized by ternary experimental data. The generic bond\nenergy formalism (GBEF) has thus been derived to provide the MQMPA great\nflexibility to describe ternary solutions with complex configurations.\nMoreover, the GBEF is more concise than the formula derived by a combinatorial\nKohler-Toop method. The concise GBEF is in the respect more conveniently\nprogrammed. Eventually, the Cu-Li-Sn liquid where both SRO and clustering among\natoms occur is employed to validate the effectiveness and reliability of the\nGBEF within the MQMPA."
    },
    {
        "anchor": "Dynamically altered conductance in an Organic Thin Film Memristive\n  Device: The memristive device is one of the basic elements of novel, brain-inspired,\nfast, and energy-efficient information processing systems in which there is no\nseparation between memorization and information analysis functions. Since the\nfirst demonstration of the resistive switching effect, several types of\nmemristive devices have been developed. In most of them, the memristive effect\noriginates from direct modification of the conducting area, e.g. conducting\nfilament formation/disintegration, or semiconductor doping/dedoping. Here, we\nreport a solution-processed lateral memristive device based on a new\nconductivity modulation mechanism. The device architecture resembles that of an\norganic field-effect transistor in which the top gate electrode is replaced\nwith an additional insulator layer containing mobile ions. Alteration of the\nion distribution under the influence of applied potential changes the electric\nfield, modifying the conductivity of the semiconductor channel. The devices\nexhibit highly stable current-voltage hysteresis loops and Short-Term\nPlasticity (STP). We also demonstrate short-term synaptic plasticity with\ntunable time constants.",
        "positive": "Shape of ammonium chloride dendrite tips at small supersaturation: We report detailed shape measurements of the tips of three-dimensional\nammonium chloride dendrites grown from supersaturated aqueous solution. For\ngrowth at small supersaturation, we compare two different models: parabolic\nwith a fourth-order correction, and power law. Neither is ideal, but the\nfourth-order fit appears to provide the most robust description of both the tip\nshape and position for this material. For that fit, the magnitude of the\nfourth-order coefficient is about half of the theoretically expected value."
    },
    {
        "anchor": "Interfacial interaction in monolayer transition metal dichalcogenides\n  (MX2)/metal oxide heterostructures and its effects on electronic and optical\n  properties: The case of MX2/CeO2: Two-dimensional transition metal dichalcogenides (MX2)/metal oxide\nheterostructures have shown unique physical properties, making them promising\nmaterials for various applications ranging from photocatalysis to solar energy\nconversion. Understanding the interfacial interactions is highly desirable for\ndesigning these heterostructures having excellent performance. Here we\nsystematically study the interfacial interaction in monolayer MX2 (M=Mo, W;\nX=S, Se)/CeO2 heterostructures and its effects on electronic and optical\nproperties by density functional theory. It is found that the interfacial\ninteraction in the MX2/CeO2 depends predominantly on the chalcogen (X) element.\nParticularly, the band gap variation and important electronic states at\nconduction band minimum or valence band maximum of the heterostructures are\ndetermined by the strength of interfacial interaction. The MX2/CeO2\nheterostructures with the same chalcogen (X) element have similar absorption\nspectra from ultraviolet to near-infrared regions. These results suggest that\nthe chalcogen (X) element is a key factor in tuning the properties of MX2/metal\noxide heterostructures.",
        "positive": "Observation of a Dirac nodal line in AlB2: We have performed angle-resolved photoemission spectroscopy of AlB2 which is\nisostructural to high-temperature superconductor MgB2. Using soft-x-ray\nphotons, we accurately determined the three-dimensional bulk band structure and\nfound a highly anisotropic Dirac-cone band at the K point in the bulk hexagonal\nBrillouin zone. This band disperses downward on approaching the H point while\nkeeping its degeneracy at the Dirac point, producing a characteristic Dirac\nnodal line along the KH line. We also found that the band structure of AlB2 is\nregarded as a heavily electron-doped version of MgB2 and is therefore well\nsuited for fully visualizing the predicted Dirac nodal line. The present\nresults suggest that (Al,Mg)B2 system is a promising platform for studying the\ninterplay among Dirac nodal line, carrier doping, and possible topological\nsuperconducting properties."
    },
    {
        "anchor": "Evidence for First Order Cubic Paraelectric to Rhombohedral\n  Ferroelectric Phase Transition in 0.8BiFeO3-0.2Pb(Fe1/2Nb1/2)O3: The current controversies about the existence of an intermediate 'beta' phase\nof BiFeO_3 and the high temperature paraelectric 'gamma' phase are resolved by\nstudying the sequence of ferroic transitions in\n0.8BiFeO_3-0.2Pb(Fe_1/2Nb_1/2)O_3 (BF-0.2PFN) with lowered transition\ntemperature. It is shown that the room temperature ferroelectric phase of\n0.8BF-0.2PFN in the R3c space group transforms to the paraelectric/paraelastic\ncubic (Pm-3m) phase directly without any intermediate 'beta' phase reported in\nthe literature. This transition is of first order type as confirmed by the\ncoexistence of R3c and Pm-3m phases over a 100K range and a discontinuous\nchange in the unit cell volume.",
        "positive": "Chemistry and structure of homoepitaxial SrTiO$_3$ films and their\n  influence on oxide-heterostructure interfaces: The properties of single-crystal SrTiO$_{3}$ substrates and homoepitaxial\nSrTiO$_{3}$ films grown by pulsed laser deposition have been compared, in order\nto understand the loss of interfacial conductivity when more than a critical\nthickness of nominally homoepitaxial SrTiO$_{3}$ is inserted between a\nLaAlO$_{3}$ film and a SrTiO$_{3}$ substrate. In particular, the chemical\ncomposition and the structure of homoepitaxial SrTiO$_{3}$ investigated by\nlow-energy ion-scattering and surface x-ray diffraction, show that for\ninsulating heterointerfaces, a Sr-excess is present between the LaAlO$_{3}$ and\nhomoepitaxial SrTiO$_{3}$. Furthermore, an increase in the out-of-plane lattice\nconstant is observed in LaAlO$_{3}$, indicating that the conductivity both with\nand without insertion of SrTiO$_{3}$ thin film originates from a Zener\nbreakdown associated with the polar catastrophe. When more than a critical\nthickness of homoepitaxial SrTiO$_{3}$ is inserted between LaAlO$_3$ and\nSrTiO$_3$, the electrons transferred by the electronic reconstruction are\ntrapped by the formation of a Sr-rich secondary phase and Sr-vacancies. The\nmigration of Sr towards the surface of homoepitaxial STO and accompanying loss\nof interfacial conductivity can be delayed by reducing the Sr-content in the\nPLD target."
    },
    {
        "anchor": "Possible complete miscibility of $(BN)_x(C_2)_{1-x}$ alloys: The stabilities of $(BN)_x(C_2)_{1-x}$ alloys and related superlattices are\ninvestigated by ab initio pseudopotential calculations. We find that the\n$(BN)_1/(C_2)_1$ superlattices in (111) orientations have the lowest formation\nenergy among many short-range ordered $BNC_2$ structures due to the smallest\nnumber of B-C and C-N bonds. Based on the calculated formation energies at\nseveral compositions and for various ordered structures and assuming\nthermodynamic equilibrium, the solid solution phase diagram of\n$(BN)_x(C_2)_{1-x}$ alloys is constructed. We find that the complete\nmiscibility of $(BN)_x(C_2)_{1-x}$ alloys is possible, which is in contrast\nwith previous theoretical predictions but in agreement with experimental\nreports.",
        "positive": "Impact of OH-groups on the mobility of linkers and guests in UiO-66 (Zr): UiO-66 (Zr) is a metal-organic framework known for its thermal and chemical\nstability and wide range of possible applications. In particular, this material\nhas high separation selectivity of various hydrocarbon mixtures. Moreover, it\nis was shown that the performance depends on the hydroxylation state of\nmaterial (reversible phase transition $Zr_{6}O_{4}(OH)_{4} {\\longrightarrow}\nZr_{6}O_{6}$ at 250 - 300 ${\\deg}C)$. Despite all the attention the UiO-66\nreceived over past few years, the impact of the dehydroxylation on its\nproperties remains poorly understood. In this contribution we apply $^{2}$H NMR\nexperimental method in order to compare the mobility of butane isomers in\nhydroxylated and dehydroxylated form of UiO-66. We provide estimations of the\ntranslational diffusion coefficients and show which hydroxylation state of the\nmaterial has higher separation selectivity. Moreover, the impact of the\nhydroxylation on the structural mobility of UiO-66 is discussed. Correlation\nbetween parameters of structural dynamics and the diffusivity of guest\nmolecules indicates that for the microporous material with small windows even\nsubtle changes can lead to a tangible improvement of the properties."
    },
    {
        "anchor": "Fast computing of scattering maps of nanostructures using graphical\n  processing units: Scattering maps from strained or disordered nano-structures around a Bragg\nreflection can either be computed quickly using approximations and a (Fast)\nFourier transform, or using individual atomic positions. In this article we\nshow that it is possible to compute up to 4.10^10 $reflections.atoms/s using a\nsingle graphic card, and we evaluate how this speed depends on number of atoms\nand points in reciprocal space. An open-source software library (PyNX) allowing\neasy scattering computations (including grazing incidence conditions) in the\nPython language is described, with examples of scattering from non-ideal\nnanostructures.",
        "positive": "Atomistic theory of spin relaxation in self-assembled\n  In$_{1-x}$Ga$_x$As/GaAs quantum dots at zero magnetic field: We present full atomistic calculations of the spin-flip time (T$_{1}$) of\nelectrons and holes mediated by acoustic phonons in self-assembled\nIn$_{1-x}$Ga$_x$As/GaAs quantum dots at zero magnetic field. At low magnetic\nfield, the first-order process is suppressed, and the second-order process\nbecomes dominant. We find that the spin-phonon-interaction induced spin\nrelaxation time is 40 - 80 s for electrons, and 1 - 20 ms for holes at 4.2 K.\nThe calculated hole-spin relaxation times are in good agreement with recent\nexperiments, which suggests that the two-phonon process is the main relaxation\nmechanism for hole-spin relaxation in the self-assembled quantum dots at zero\nfield. We further clarify the structural and alloy composition effects on the\nspin relaxation in the quantum dots."
    },
    {
        "anchor": "A pseudopotential study of electron-hole excitations in colloidal,\n  free-standing InAs quantum dots: Excitonic spectra are calculated for free-standing, surface passivated InAs\nquantum dots using atomic pseudopotentials for the single-particle states and\nscreened Coulomb interactions for the two-body terms. We present an analysis of\nthe single particle states involved in each excitation in terms of their\nangular momenta and Bloch-wave parentage. We find that (i) in agreement with\nother pseudopotential studies of CdSe and InP quantum dots, but in contrast to\nk.p calculations, dot states wavefunction exhibit strong odd-even angular\nmomentum envelope function mixing (e.g. $s$ with $p$) and large\nvalence-conduction coupling. (ii) While the pseudopotential approach produced\nvery good agreement with experiment for free-standing, colloidal CdSe and InP\ndots, and for self-assembled (GaAs-embedded) InAs dots, here the predicted\nspectrum does {\\em not} agree well with the measured (ensemble average over dot\nsizes) spectra. (1) Our calculated excitonic gap is larger than the PL measure\none, and (2) while the spacing between the lowest excitons is reproduced, the\nspacings between higher excitons is not fit well. Discrepancy (1) could result\nfrom surface states emission. As for (2), agreement is improved when account is\ntaken of the finite size distribution in the experimental data. (iii) We find\nthat the single particle gap scales as $R^{-1.01}$ (not $R^{-2}$), that the\nscreened (unscreened) electron-hole Coulomb interaction scales as $R^{-1.79}$\n($R^{-0.7}$), and that the eccitonic gap sclaes as $R^{-0.9}$. These scaling\nlaws are different from those expected from simple models.",
        "positive": "Electronic and magnetic properties of transition-metal doped ScN for\n  spintronics applications: Motivated by the ongoing interest in nitrides as materials for spintronics\napplications we have studied effects of doping with magnetic transition-metal\nelements (T=Cr,Mn,Fe,Co and Ni) on the electronic properties of semiconducting\nscandium nitride. Using density functional together with the generalized\ngradient approximation (GGA) as well as PBE0r hybrid functional (with different\nmixing of the exact exchange), two different doping amounts 25\\% ($\\rm\nSc_{0.75}T_{0.25}N$) and 10\\% ($\\rm Sc_{0.9}T_{0.1}N$) have been investigated.\nThis is done in comparison to the reference compound ScN with a strong focus on\nidentifying candidates for half-metallic or semiconducting ferromagnetic ground\nstates. Within GGA, only $\\rm Sc_{0.75}Cr_{0.25}N$ and $\\rm\nSc_{0.75}Mn_{0.25}N$ are found to be semiconducting and half-metallic,\nrespectively. The use of hybrid functional changes drastically these finding,\nwhere $\\rm Sc_{0.75}Fe(Co,Ni)_{0.25}N$ become half-metals and $\\rm\nSc_{0.75}Cr(Mn)_{0.25}N$ are found both semiconductors. However, additional\ncalculations assuming antiferromagnetic ordering revealed that $\\rm\nSc_{0.75}Cr_{0.25}N$ is the only compound of this series, which prefers an\nantiferromagnetic (and semiconducting) ground state. For the lower\nconcentration, $\\rm Sc_{0.9}T_{0.1}N$, similar results have been predicted, and\nall the doped nitrides are found to prefer ferromagnetic ground state over an\nantiferromagnetic one."
    },
    {
        "anchor": "DyFeO3 electrode material with ultra-wide voltage window for aqueous\n  symmetric supercapacitors: Aqueous supercapacitors (SCs) encounter limitations in operational voltage\nand energy density due to the low decomposition voltage of water. Here, we\nfabricate aqueous symmetric supercapacitors (ASSCs) employing DyFeO3 as an\nelectrode material. This hybrid SC in a 0.5 M Na2SO4 aqueous electrolyte\nexhibits a significantly high working voltage of 2.5 V, with an energy density\nof 41.81 Wh/kg at a power density of 1250 W/kg, maintaining 94% capacitance\nretention after 5000 cycles. By incorporating 20% volume of acetonitrile with\nwater in the electrolyte, we extend the potential window to 3.1 V, with an\nenergy density of 84.43 Wh/kg at a power density of 1550 W/kg. The\nas-fabricated ASSC shows promising stability during a 300-hour float voltage\ntest with almost intact capacitance retention and Coulombic efficiency. For the\nfirst time, our study unveils the potential of porous DyFeO3 as an electrode\nmaterial for advancing ASSCs, featuring an unprecedented ultra-wide voltage\nwindow, along with significantly large energy and power densities.",
        "positive": "Ubiquitous topological states of phonons in solids: Silicon as a model\n  material: Research on topological physics of phonons has attracted enormous interest\nbut demands appropriate model materials. Our {\\it ab initio} calculations\nidentify silicon as an ideal candidate material containing extraordinarily rich\ntopological phonon states. In silicon, we identify various topological nodal\nlines protected by glide mirror or mirror symmetries and characterized by\nquantized Berry phase $\\pi$, which gives drumhead surface states observable\nfrom any surface orientations. Remarkably, a novel type of topological nexus\nphonon is discovered, which is featured by double Fermi-arc-like surface states\nand distinguished from Weyl phonons by requiring neither inversion nor\ntime-reversal symmetry breaking. Versatile topological states can be created\nfrom the nexus phonons, such as Hopf nodal link by strain. Furthermore, we\ngeneralize the symmetry analysis to other centrosymmetric systems and find\nnumerous candidate materials, demonstrating the ubiquitous existence of\ntopological phonons in solids. These findings open up new opportunities for\nstudying topological phonons in realistic materials and their influence on\nsurface physics."
    },
    {
        "anchor": "Origin of the unconventional magnetoresistance in Sr2FeMoO6: The unusual magnetoresistance (MR) behavior in Sr2FeMoO6, recently termed as\nspin-valve type MR (SVMR), presents several anomalies that are little\nunderstood so far. The difficulty in probing the origin of this phenomenon,\narising from the magnetic property of only a small volume fraction of the\nferromagnetic bulk, is circumvented in the present study by the use of ac\nsusceptibility measurements that are sensitive to the slope rather than the\nmagnitude of the magnetization. The present study unravels a spin-glass (SG)\nlike surface layer around each soft ferromagnetic (FM) grain of Sr2FeMoO6. It\nis also observed that there is a very strong exchange coupling between the two,\ngenerating `exchange bias' effect, which consequently creates the `valve',\nresponsible for the unusual MR effects.",
        "positive": "Reversible Photomechanical Switching of Individual Engineered Molecules\n  at a Surface: We have observed reversible light-induced mechanical switching for a single\norganic molecule bound to a metal surface. Scanning tunneling microscopy (STM)\nwas used to image the features of an individual azobenzene molecule on Au(111)\nbefore and after reversibly cycling its mechanical structure between trans and\ncis states using light. Azobenzene molecules were engineered to increase their\nsurface photomechanical activity by attaching varying numbers of tert-butyl\n(TB) ligands (\"legs\") to the azobenzene phenyl rings. STM images show that\nincreasing the number of TB legs \"lifts\" the azobenzene molecules from the\nsubstrate, thereby increasing molecular photomechanical activity by decreasing\nmolecule-surface coupling."
    },
    {
        "anchor": "Thermal resistance of GaN/AlN graded interfaces: Compositionally graded interfaces in power electronic devices eliminate\ndislocations, but they can also decrease thermal conduction, leading to\noverheating. We quantify the thermal resistances of GaN/AlN graded interfaces\nof varying thickness using ab initio Green's functions, and compare them with\nthe abrupt interface case. A non-trivial power dependence of the thermal\nresistance versus interface thickness emerges from the interplay of alloy and\nmismatch scattering mechanisms. We show that the overall behavior of such\ngraded interfaces is very similar to that of a thin-film of an effective alloy\nin the length scales relevant to real interfaces.",
        "positive": "Kelvin probe characterization of buried graphitic microchannels in\n  single-crystal diamond: In this work, we present an investigation by Kelvin Probe Microscopy (KPM) of\nburied graphitic microchannels fabricated in single-crystal diamond by direct\nMeV ion microbeam writing. Metal deposition of variable-thickness masks was\nadopted to implant channels with emerging endpoints and high temperature\nannealing was performed in order to induce the graphitization of the\nhighly-damaged buried region. When an electrical current was flowing through\nthe biased buried channel, the structure was clearly evidenced by KPM maps of\nthe electrical potential of the surface region overlying the channel at\nincreasing distances from the grounded electrode. The KPM profiling shows\nregions of opposite contrast located at different distances from the endpoints\nof the channel. This effect is attributed to the different electrical\nconduction properties of the surface and of the buried graphitic layer. The\nmodel adopted to interpret these KPM maps and profiles proved to be suitable\nfor the electronic characterization of buried conductive channels, providing a\nnon-invasive method to measure the local resistivity with a micrometer\nresolution. The results demonstrate the potential of the technique as a\npowerful diagnostic tool to monitor the functionality of all-carbon\ngraphite/diamond devices to be fabricated by MeV ion beam lithography."
    },
    {
        "anchor": "CASM Monte Carlo: Calculations of the thermodynamic and kinetic\n  properties of complex multicomponent crystals: Monte Carlo techniques play a central role in statistical mechanics\napproaches for connecting macroscopic thermodynamic and kinetic properties to\nthe electronic structure of a material. This paper describes the implementation\nof Monte Carlo techniques for the study multicomponent crystalline materials\nwithin the Clusters Approach to Statistical Mechanics (CASM) software suite,\nand demonstrates their use in model systems to calculate free energies and\nkinetic coefficients, study phase transitions, and construct first-principles\nbased phase diagrams. Many crystal structures are complex, with multiple\nsublattices occupied by differing sets of chemical species, along with the\npresence of vacancies or interstitial species. This imposes constraints on\nconcentration variables, the form of thermodynamic potentials, and the values\nof kinetic transport coefficients. The framework used by CASM to formulate\nthermodynamic potentials and kinetic transport coefficients accounting for\narbitrarily complex crystal structures is presented and demonstrated with\nexamples applying it to crystal systems of increasing complexity. Additionally,\na new software package is introduced, casm-flow, which helps automate the\nsetup, submission, management, and analysis of Monte Carlo simulations\nperformed using CASM.",
        "positive": "Reinforcement learning-guided long-timescale simulation of hydrogen\n  transport in metals: Atomic diffusion in solids is an important process in various phenomena.\nHowever, atomistic simulations of diffusion processes are confronted with the\ntimescale problem: the accessible simulation time is usually far shorter than\nthat of experimental interests. In this work, we developed a long-timescale\nmethod using reinforcement learning that simulates diffusion processes. As a\ntestbed, we simulate hydrogen diffusion in pure metals and a medium entropy\nalloy, CrCoNi, getting hydrogen diffusivity reasonably consistent with previous\nexperiments. We also demonstrate that our method can accelerate the sampling of\nlow-energy configurations compared to the Metropolis-Hastings algorithm using\nhydrogen migration to copper (111) surface sites as an example."
    },
    {
        "anchor": "Nucleation and growth of catalyst-free ZnO nanostructures: This paper deals with the investigations on the nucleation and growth of ZnO\nnanostructures in a catalyst free synthesis. The ZnO nanostructures have been\nformed by evaporation of Zn (99.99%) in O_2 and Ar atmosphere in single zone\nfurnace under two temperature regions, region A (~1173-1073K) and region B\n(~873-773K). Through application of XRD and TEM techniques, it has been shown\nthat first ZnO is formed which changes to ZnOx through creation of oxygen\nvacancies. The ZnOx acts as self-catalyst and leads to formation of various\nnanostructures. Those observed in the present investigation are nanotetrapods\n(1D, diameter ~ 70-450nm, length ~ 2-4.5mm) nanorods (1D, diameter ~ 45-95nm,\nlength ~ 2.5-4.5mm), nanoflowers(2D,central core diameter ~ 90-185nm, length of\npetals/nanorod ~ 1.0-3.5mm) and nanoparticles (3D, size ~ 0.85-2.5mm). These\nnanostructures have been revealed by SEM explorations. Attempts have been made\nto explain the formation of the various nanostructures in terms of the creation\nand distribution of the ZnOx, the temperature as well as oxygenation\nconditions.",
        "positive": "On the elusive anti-bayerite structure: Sequential deprotonation of the Cr3+ hexahydrate in an alkaline environment\nup to the stage of a charge-neutral active hydroxide was studied via density\nfunctional theory. The deprotonation could be characterized as autocatalytic\nsince upon completion of every H-abstraction stage, Cr was found to mediate O-H\ndissociation in the next stage by pre-conditioning the ligand O atom that\ncontributes the highest 2s density into Cr-4s based molecular orbitals; the\nlatter amounts to a greater Cr-O distance due to increased charge density along\nthe Cr-O axis. A direct effect of such Cr-4s/O-2s mixing is the reduction of\nelectronegativity of the ligand-O atom and a corresponding high Voronoi\ndeformation density (VDD) of the attached ligand-H atoms. Based on bonding\nenergy decomposition, a facial to meridional isomer ratio of between 2:1 and\n3:1 was derived as the most probable stereochemical mix of the active\nhydroxide; the latter forms, by mutual donation and acceptance, six hydrogen\nbonds with second hydration shell molecules."
    },
    {
        "anchor": "MyElas: An automatized tool-kit for high-throughput calculation,\n  post-processing and visualization of elasticity and related properties of\n  solids: Elasticity is one of the most fundamental mechanical properties of solid. In\nhigh-throughput design of advanced materials, there is an imperative demand for\nthe capability to quickly calculate and screen a massive pool of candidate\nstructures. A fully automatized pipeline with minimal human intervention is the\nkey to provide high efficiency to achieve the goal. Here, we introduce a\ntool-kit MyElas that aims to address this problem by forging all\npre-processing, elastic constant and other related property calculations, and\npost-processing into an integrated framework that automatically performs the\nassigned tasks to drive data flowing through parallelized pipelines from input\nto output. The core of MyElas is to calculate the second and third order\nelastic constants of a solid with the energy-strain method from\nfirst-principles. MyElas can auto-analyze the elastic constants, to derive\nother related physical quantities. Furthermore, the tool-kit also integrates a\nvisualization function, which can, for example, plot the spatial anisotropy of\nelastic modulus and sound velocity of monocrystalline. The validity and\nefficiency of the toolkit are tested and bench-marked on several typical\nsystems.",
        "positive": "Chiral fermion reversal in chiral crystals: In materials chiral fermions such as Weyl fermions are characterized by\nnonzero chiral charges, which are singular points of Berry curvature in\nmomentum space. Recently, new types of chiral fermions beyond Weyl fermions\nhave been discovered in structurally chiral crystals CoSi, RhSi and PtAl. Here,\nwe have synthesized RhSn single crystals, which have opposite structural\nchirality to the CoSi crystals we previously studied. Using angle-resolved\nphotoemission spectroscopy, we show that the bulk electronic structures of RhSn\nare consistent with the band calculations and observe evident surface Fermi\narcs and helical surface bands, confirming the existence of chiral fermions in\nRhSn. It is noteworthy that the helical surface bands of the RhSn and CoSi\ncrystals have opposite handedness, meaning that the chiral fermions are\nreversed in the crystals of opposite structural chirality. Our discovery\nestablishes a direct connection between chiral fermions in momentum space and\nchiral lattices in real space."
    },
    {
        "anchor": "Electric and Magnetic Responses of Two-dimensional Dirac Electrons in\n  Organic Conductor $\u03b1$-(BETS)$_2$I$_3$: Effect of spin-orbit coupling (SOC) on Dirac electrons in the organic\nconductor $\\alpha$-(BETS)$_2$I$_3$ [BETS =\nbis(ethylenedithio)tetraselenafulvalene] has been examined by calculating\nelectric conductivity and spin magnetic susceptibility. A tight-binding (TB)\nmodel with real and imaginary transfer energies is derived using\nfirst-principles density-functional theory method. The conductivity without the\nSOC depends on both anisotropies of the velocity of the Dirac cone and the\ntiling of the cone. Such conductivity is suppressed by the SOC, which gives\nrise to the imaginary part of the transfer energy. Due to the SOC, we find at\nlow temperatures that the reduction of the conductivity becomes large and that\nthe anisotropy of the conductivity is reduced. A nearly constant conductivity\nat high temperatures is obtained by an electron--phonon (e--p) scattering.\nFurther, the property of the Dirac cone is examined for the spin\nsusceptibility, which is mainly determined by the density of states (DOS). The\nresult is compared with the case of the organic conductor\n$\\alpha$-(BEDT-TTF)$_2$I$_3$ [BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene],\nwhich provides the Dirac cone without the SOC. The relevance to experiments is\ndiscussed.",
        "positive": "A New Direct Process to Prepare YBa2Cu3O7-&#61540; films on Biaxially\n  Textured Ag{110}<211>: YBCO films were successfully prepared on biaxially textured Ag{110}<211>\nsubstrates by using pulsed laser deposition. X-ray diffraction results showed\nthat the degree of preferential orientation of Ag{110}<211> substrates varied\nwith increasing annealing temperature. With a thin template layer deposited at\nlow temperature, YBCO film with c-axis orientation and in-plane biaxial\nalignment could be obtained at high deposition temperature. Scanning electron\nmicroscopy observation revealed that YBCO grains enlarged but Ag grains on the\nsurface of the YBCO films became smaller with increasing deposition\ntemperature. At optimal deposition conditions, Ag atoms diffuse into the YBCO\ngrain boundaries, and then fill in the weak-link regions in the YBCO film,\nresulting in the conduction easier. Jc value of 5&#61620;105A/cm2 was obtained\nat 77K and zero magnetic field for the best YBCO film in our work."
    },
    {
        "anchor": "Optical functions and electronic structure of CuInSe2, CuGaSe2, CuInS2,\n  and CuGaS2: We report on the complex dielectric tensor components of four chalcopyrite\nsemiconductors in the optical energy range (1.4-5.2 eV, from 0.9 eV for\nCuInSe2) determined at room temperature by spectroscopic ellipsometry. Our\nresults were obtained on single crystals of CuInSe2, CuGaSe2, CuInS2, and\nCuGaS2. Values of refractive indices n, extinction coefficients k and\nnormal-incidence reflectivity R in the two different polarizations are given\nand compared with earlier data where available. We analyze in detail the\nstructures of the dielectric function observed in the studied energy region.\nCritical-point parameters of electronic transitions are obtained from fitting\nof numerically calculated second-derivative spectra. Experimental energies and\npolarizations are discussed on the basis of published band structure\ncalculations.",
        "positive": "Predicted electronic markers for polytypes of LaOBiS2 examined via\n  angular resolved photoemission spectroscopy: The natural periodic stacking of symmetry-inequivalent planes in layered\ncompounds can lead to the formation of natural superlattices; albeit close in\ntotal energy, (thus in their thermodynamic stability), such polytype\nsuperlattices can exhibit different structural symmetries, thus have markedly\ndifferent electronic properties which can in turn be used as \"structural\nmarkers\". We illustrate this general principle on the layered LaOBiS2 compound\nwhere density-functional theory (DFT) calculations on the (BiS2)/(LaO)/(BiS2)\npolytype superlattices reveal both qualitatively and quantitatively distinct\nelectronic structure markers associated with the Rashba physics, yet the total\nenergies are only ~ 0.1 meV apart. This opens the exciting possibility of\nidentifying subtle structural features via electronic markers. We show that the\npattern of removal of band degeneracies in different polytypes by the different\nforms of symmetry breaking leads to new Rashba \"mini gaps\" with characteristic\nRashba parameters that can be determined from spectroscopy, thereby narrowing\ndown the physically possible polytypes. By identifying these distinct\nDFT-predicted fingerprints via ARPES measurements on LaBiOS2 we found the\ndominant polytype with small amounts of mixtures of other polytypes. This\nconclusion, consistent with neutron scattering results, establishes ARPES\ndetection of theoretically established electronic markers as a powerful tool to\ndelineate energetically quasidegenerate polytypes."
    },
    {
        "anchor": "Systematic and objective identification of the microstructure around\n  damage directly from images: An original experimental approach is presented to automatically determine the\naverage phase distribution around damage sites in multi-phase materials. An\nobjective measure is found to be the average intensity around damage sites,\ncalculated using many images. This method has the following benefits: no phase\nidentification or manual interventions are required, and statistical\nfluctuations and measurement noise are effectively averaged. The method is\ndemonstrated for dual-phase steel, revealing subtle unexpected differences in\nthe morphology surrounding damage in strongly and weakly banded\nmicrostructures.",
        "positive": "Anomalous magneto-structural behavior of MnBi explained: a path towards\n  an improved permanent magnet: Low-temperature MnBi (hexagonal NiAs phase) exhibits anomalies in the lattice\nconstants (a, c) and bulk elastic modulus (B) below 100 K, spin reorientation\nand magnetic susceptibility maximum near 90 K, and, importantly for\nhigh-temperature magnetic applications, an increasing coercivity (unique to\nMnBi) above 180 K. We calculate the total energy and magneto-anisotropy energy\n(MAE) versus (a, c) using DFT+U methods. We reproduce and explain all the above\nanomalies. We predict that coercivity and MAE increase due to increasing a,\nsuggesting means to improve MnBi permanent magnets."
    },
    {
        "anchor": "Studies on temperature dependent semiconductor to metal transitions in\n  ZnO thin films sparsely doped with Al: For a detailed study on the semiconductor to metal transition (SMT) in ZnO\nthin films doped with Al in the concentration range from 0.02 to 2%, we grew\nthese films on (0001) sapphire substrates using sequential pulsed laser\ndeposition. It was found that the Al concentration in the films increased\nmonotonically with the ratio of ablation durations of the Alumina and ZnO\ntargets used during the deposition. Using X-ray photo electron spectroscopy it\nwas found that while most of the Al atoms occupy the Zn sites in the ZnO\nlattice, a small fraction of the Al also gets into the grain boundaries present\nin the films. The observed SMT temperature decreased from ~ 270 to ~ 50 K with\nincrease in the Al concentration from 0.02 to 0.25 %. In the Al concentration\nrange of ~ 0.5 to 2 % these doped ZnO films showed metallic behavior at all the\ntemperatures without undergoing any SMT. A theoretical model based on thermal\nactivation of electrons and electron scatterings due to the grain boundaries,\nionic impurities and phonons has been developed to explain the observed\nconcentration and temperature dependent SMT.",
        "positive": "Optical absorption of divalent metal tungstates: Correlation between the\n  band-gap energy and the cation ionic radius: We have carried out optical-absorption and reflectance measurements at room\ntemperature in single crystals of AWO4 tungstates (A = Ba, Ca, Cd, Cu, Pb, Sr,\nand Zn). From the experimental results their band-gap energy has been\ndetermined to be 5.26 eV (BaWO4), 5.08 eV (SrWO4), 4.94 eV (CaWO4), 4.15 eV\n(CdWO4), 3.9-4.4 eV (ZnWO4), 3.8-4.2 eV (PbWO4), and 2.3 eV (CuWO4). The\nresults are discussed in terms of the electronic structure of the studied\ntungstates. It has been found that those compounds where only the s electron\nstates of the A2+ cation hybridize with the O 2p and W 5d states (e.g BaWO4)\nhave larger band-gap energies than those where also p, d, and f states of the\nA2+ cation contribute to the top of the valence band and the bottom of the\nconduction band (e.g. PbWO4). The results are of importance in view of the\nlarge discrepancies existent in prevoiusly published data."
    },
    {
        "anchor": "Spin dependent transport in organic light-emitting diodes: Electrically Detected Magnetic Resonance (EDMR) was used to study a series of\nmultilayer organic devices based on aluminum (III) 8-hydroxyquinoline. These\ndevices were designed to identify the micoscopic origin of different spin\ndependent process, i.e. hopping and exciton formation. EDMR is demonstrated to\nprobe molecular orbitals of charge, and thus indirectly explore interfaces,\nexciton formation, charge accumalation and electric fields in operating organic\nbased devices.",
        "positive": "Controlled irradiation hardening of tungsten by cyclic recrystallization: The economical lifetime of the divertor is a key concern for realizing\nnuclear fusion reactors that may solve the world's energy problem. A main risk\nis thermo-mechanical failure of the plasma-facing tungsten monoblocks, as a\nconsequence of irradiation hardening induced by neutron displacement cascades.\nLifetime extensions that could be carried out without prolonged maintenance\nperiods are desired. In this work, the effects of potential treatments for\nextending the lifetime of an operational reactor are explored. The proposed\ntreatments make use of cyclic recrystallization processes that can occur in\nneutron-irradiated tungsten. Evolution of the microstructure under\nnon-isothermal conditions is investigated, employing a multi-scale model that\nincludes a physically-based mean-field recrystallization model and a cluster\ndynamics model for neutron irradiation effects. The model takes into account\nmicrostructural properties such as grain size and displacement-induced defect\nconcentrations. The evolution of a hardness indicator under neutron irradiation\nwas studied. The results reveal that, for the given microstructure and under\nthe assumed model behaviour, periodical extra heating can have a significant\npositive influence on controlling the irradiation hardening. For example, at\n800 C, if extra annealing at 1200 C was applied after every 100 hrs for the\nduration of 1 hr, then the hardness indicator reduces from maximum 140 to below\n70."
    },
    {
        "anchor": "Correlation-Driven Dimerization and Topological Gap Opening in\n  Isotropically Strained Graphene: The phase diagram of isotropically expanded graphene cannot be correctly\npredicted by ignoring either electron correlations, or mobile carbons, or the\neffect of applied stress, as was done so far. We calculate the ground state\nenthalpy (not just energy) of strained graphene by an accurate off-lattice\nQuantum Monte Carlo (QMC) correlated ansatz of great variational flexibility.\nFollowing undistorted semimetallic graphene (SEM) at low strain,\nmulti-determinant Heitler-London correlations stabilize between $\\simeq$8.5%\nand $\\simeq$15% strain an insulating Kekule-like dimerized (DIM) state. Closer\nto a crystallized resonating-valence bond than to a Peierls state, the DIM\nstate prevails over the competing antiferromagnetic insulating (AFI) state\nfavored by density-functional calculations which we conduct in parallel. The\nDIM stressed graphene insulator, whose gap is predicted to grow in excess of 1\neV before failure near 15% strain, is topological in nature, implying under\ncertain conditions 1D metallic interface states lying in the bulk energy gap.",
        "positive": "Thermal Transport in Amorphous Graphene with Varying Structural Quality: The synthesis of wafer-scale two-dimensional amorphous carbon monolayers has\nbeen recently demonstrated. This material presents useful properties when\nintegrated as coating of metals, semiconductors or magnetic materials, such as\nenabling efficient atomic layer deposition and hence fostering the development\nof ultracompact technologies. Here we propose a characterization of how the\nstructural degree of amorphousness of such carbon membranes could be controlled\nby the crystal growth temperature. We also identify how energy is dissipated in\nthis material by a systematic analysis of emerging vibrational modes whose\nlocalization increases with the loss of spatial symmetries, resulting in a\ntunable thermal conductivity varying by more than two orders of magnitude. Our\nsimulations provide some recipe to design most suitable \"amorphous graphene\"\nbased on the target applications such as ultrathin heat spreaders, energy\nharvesters or insulating thermal barriers."
    },
    {
        "anchor": "The structural properties of the multi-layer graphene/4H-SiC(000-1)\n  system as determined by Surface X-ray Diffraction: We present a structural analysis of the multi-layer graphene-4HSiC(000-1})\nsystem using Surface X-Ray Reflectivity. We show for the first time that\ngraphene films grown on the C-terminated (000-1}) surface have a\ngraphene-substrate bond length that is very short (0.162nm). The measured\ndistance rules out a weak Van der Waals interaction to the substrate and\ninstead indicates a strong bond between the first graphene layer and the bulk\nas predicted by ab-initio calculations. The measurements also indicate that\nmulti-layer graphene grows in a near turbostratic mode on this surface. This\nresult may explain the lack of a broken graphene symmetry inferred from\nconduction measurements on this system [C. Berger et al., Science 312, 1191\n(2006)].",
        "positive": "Rounding of a first-order magnetic phase transition in Ga doped\n  La0.67Ca0.33MnO3: The effect of disorder on the critical properties of the ferromagnetic phase\ntransition in colossal magnetoresistive manganite La0.67Ca0.33MnO3 has been\nstudied by substituting Ga for Mn. It is found that, upon 10% Ga substitution,\nthe peak in the specific heat at the Curie point T_C changes drastically and\nappears as a small anomaly. Static magnetization data analyzed in the\nasymptotic critical region using modified Arrott plots and the Kouvel-Fisher\nmethod give values for the critical exponents beta=0.387(6), gamma=1.362(2),\nand delta=4.60(3). The results show that the first-order transition in\nLa0.67Ca0.33MnO3 becomes continuous by Ga substitution. The critical properties\nof the rounded transition in La0.67Ca0.33Mn0.9Ga0.1O3 suggest that the magnetic\nsubsystem in this mixed-valent perovskite is close to that of a conventional\nisotropic ferromagnet belonging to the Heisenberg universality class with\nshort-range interactions. It is concluded that the first-order magnetic\ntransition in pure La0.67Ca0.33MnO3 is induced by fluctuations from a competing\nmode, which couples to the magnetic subsystem."
    },
    {
        "anchor": "Atomically sharp 1D SbSeI, SbSI and SbSBr with high stability and novel\n  properties for microelectronic, optoelectronic, and thermoelectric\n  applications: In scaling of transistor dimensions with low source-to-drain currents, 1D\nsemiconductors with certain electronic properties are highly desired. We\ndiscover three new 1D materials, SbSeI, SbSI and SbSBr with high stability and\nnovel electronic properties based on first principles calculations. Both\ndynamical and thermal stability of these 1D materials are examined. The\nbulk-to-1D transition results in dramatic changes in band gap, effective mass\nand static dielectric constant due to quantum confinement, making 1D SbSeI a\nhighly promising channel material for transistors with gate length shorter than\n1 nm. Under small uniaxial strain, these materials are transformed from\nindirect into direct band gap semiconductors, paving the way for optoelectronic\ndevices and mechanical sensors. Moreover, the thermoelectric performance of\nthese materials is significantly improved over their bulk counterparts.\nFinally, we demonstrate the experimental feasibility of synthesizing such\natomically sharp V-VI-VII compounds. These highly desirable properties render\nSbSeI, SbSI and SbSBr promising 1D materials for applications in future\nmicroelectronics, optoelectronics, mechanical sensors, and thermoelectrics.",
        "positive": "Emergence of ferroelectricity and spin-valley properties in\n  two-dimensional honeycomb binary compounds: By means of density functional theory calculations, we predict that several\ntwo dimensional AB binary monolayers, where A and B atoms belong to group IV or\nIII-V, are ferroelectric. Dipoles arise from the buckled structure, where the A\nand B ions are located on the sites of a bipartite corrugated honeycomb lattice\nwith trigonal symmetry. We discuss the emerging valley-dependent properties and\nthe coupling of spin and valley physics, which arise from the loss of inversion\nsymmetry, and explore the interplay between ferroelectricity and Rashba\nspin-spitting phenomena. We show that valley-related properties originate\nmainly from the binary nature of AB monolayers, while the Rashba spin-texture\ndeveloping around valleys is fully controllable and switchable by reversing the\nferroelectric polarization."
    },
    {
        "anchor": "Size effects of pyroelectric coefficient and dielectric susceptibility\n  in ferroelectric thin films: We calculate the pyrocoefficient, static dielectric susceptibility profiles\nand its thickness dependence of ferroelectric thin films. Also, the temperature\ndependences of above quantities have been calculated. For the calculations we\nuse Landau phenomenological theory, leading to Lame equations. These equations\nsubject to boundary conditions with different extrapolation length on the\nsurfaces have been solved numerically. The divergency of pyroelectric\ncoefficient and static dielectric susceptibility in the vicinity of thickness\ninduced ferroelectric phase transition (i.e. at $l\\approx l_c$ or $% T\\approx\nT_{cl}$) has been shown to be the most prominent size effect in ferroelectric\nthin films.",
        "positive": "Electronic and Lattice Dynamical Properties of Ti2SiB MAX Phase: The structural, electronic, mechanic, vibrational and thermodynamic\nproperties of Ti2SiB which is a hypothetical MAX phase compound, have been\ninvestigated using density functional theory calculations. The structural\noptimization of Ti2SiB has been performed and the results have been compared\nwith Ti2SiC, Ti2SiN, and Ti2AlB that are studied in the literature. Then the\nband structure and corresponding partial density of states are computed. In\naddition, charge density and Bader charge analysis have been performed. The\nelastic constants have been obtained, then the secondary results such as bulk\nmodulus, shear modulus, Youngs modulus, Poissons ratio, and Vickers Hardness of\npolycrystalline aggregates have been derived, and the relevant mechanical\nproperties have been discussed. Moreover, the elastic anisotropy has been\nvisualized in detail by plotting the directional dependence of compressibility,\nPoisson ratio, Youngs and Shear moduli. Furthermore, the phonon dispersion\ncurves as well as corresponding phonon PDOS, and thermodynamical properties\nsuch as free energy, entropy and heat capacity have been computed and the\nobtained results have been discussed in detail. This study provides the first\nconsiderations of Ti2SiB that could have a potential application in nuclear\nindustry."
    },
    {
        "anchor": "Total energy density as an interpretative tool: We present an unambiguous formulation for the total energy density within\ndensity-functional theory. We propose that it be used as a tool for the\ninterpretation of computed energy and electronic structure changes during\nstructural transformations and chemical reactions, augmenting the present use\nof electron density changes and changes in the Kohn-Sham local density of\nstates and Kohn-Sham energy density.",
        "positive": "Unraveling the Jahn-Teller effect in Mn doped GaN using the\n  Heyd-Scuseria-Ernzerhof hybrid functional: We present an ab-initio study of the Mn substitution for Ga in GaN using the\nHeyd-Scuseria-Ernzerhof hybrid functional (HSE). Contrary to semi-local\nfunctionals, the majority Mn t$_{2}$ manifold splits into an occupied doublet\nand an unoccupied singlet well above the Fermi-level resulting in an insulating\ngroundstate, which is further stabilized by a sizeable Jahn-Teller distortion.\nThe predictions are confirmed using $GW$ calculations and are in agreement with\nexperiment. A transition from a localized to a delocalized Mn hole state is\npredicted from GaN to GaAs."
    },
    {
        "anchor": "Non-universality in Micro-branching Instabilities in Rapid Fracture: the\n  Role of Material Properties: In spite of the apparent similarity of micro-branching instabilities in\ndifferent brittle materials, we propose that the physics determining the\ntypical length- and time-scales characterizing the post-instability patterns\ndiffer greatly from material to material. We offer a scaling theory connecting\nthe pattern characteristics to material properties (like molecular weight) in\nbrittle plastics like PMMA, and stress the fundamental differences with\npatterns in glass which are crucially influenced by 3-dimensional dynamics. In\nboth cases the present ab-initio theoretical models are still too far from\nreality, disregarding some fundamental physics of the phenomena.",
        "positive": "Towards diluted magnetism in TaAs: Magnetism in Weyl semimetals is desired to investigate the interaction\nbetween the magnetic moments and Weyl fermions, e.g. to explore anomalous\nquantum Hall phenomena. Here we demonstrate that proton irradiation is an\neffective tool to induce ferromagnetism in the Weyl semimetal TaAs. The\nintrinsic magnetism is observed with a transition temperature above room\ntemperature. The magnetic moments from d states are found to be localized\naround Ta atoms. Further, the first-principles calculations indicate that the d\nstates localized on the nearest-neighbor Ta atoms of As vacancy sites are\nresponsible for the observed magnetic moments and the long-ranged magnetic\norder. The results show the feasibility of inducing ferromagnetism in Weyl\nsemimetals so that they may facilitate the applications of this material in\nspintronics."
    },
    {
        "anchor": "The viscosity of silica fibres: The viscosity of an optical fibre over 1000 to 1150 {\\deg}C is studied by\ninscribing an optical fibre Bragg grating that can withstand temperatures up to\n1200 {\\deg}C and monitoring fibre elongation under load through the Bragg\nwavelength shift. This optical interrogation offers high accuracy and\nreliability compared to direct measurements of elongation, particularly at\nlower temperatures, thus avoiding significant experimental error. An excellent\nArrhenius fit is obtained from which an activation energy for viscous flow of\nEa = 450 kJ/mol is extracted; addition of an additional temperature dependent\npre-exponential does not change this value. This value is less than that\nidealised by some literature but consistent with other literature. The log plot\nof viscosity is overall found to be consistent with that reported in the\nliterature for silica measurements on rod and beams, but substantially higher\nto past work reported for optical fibres. The discrepancy from an idealised\nactivation energy Ea ~ 700 kJ/mol may be explained by noting the higher fictive\ntemperature of the fibre. On the other hand, past optical fibre results\nobtained by beam bending with much lower values leave questions regarding the\nmethod of viscosity measurement and the time taken for structural\nequilibration. We note that because regenerated gratings already involve\npost-annealing to stabilise their operation at higher temperature, the\nstructures are much more relaxed compared to normal fibres. This work\nhighlights the need to stabilize components for operation in harsh environments\nbefore their application, despite some mechanical compromise. Given the\nincreasing expectation of all-optical waveguide technologies operating above\n1000 {\\deg}C, the need to study the behaviour of glass over the long term\nbrings added significance to the basic understanding of glass in this regime.",
        "positive": "Precursor Selection in Hybrid Molecular Beam Epitaxy of Alkaline-Earth\n  Stannates: One of the challenges of oxide molecular beam epitaxy (MBE) is the synthesis\nof oxides containing metals with high electronegativity (metals that are hard\nto oxidize). The use of reactive organometallic precursors can potentially\naddress this issue. To investigate the formation of radicals in MBE, we\nexplored three carefully chosen metal-organic precursors of tin for SnO2 and\nBaSnO3 growth: tetramethyltin (TMT), tetraethyltin (TET), and hexamethylditin\n(HMDT). All three precursors produced single-crystalline, atomically smooth,\nand epitaxial SnO2 (101) films on r-Al2O3 in the presence of an oxygen plasma.\nThe study of growth kinetics revealed reaction-limited and flux-limited regimes\nexcept for TET, which also exhibited a decrease in deposition rate with\nincreasing temperature above 800 C. Contrary to these similarities, the\nperformance of these precursors was dramatically different for BaSnO3 growth.\nTMT and TET were ineffective in supplying adequate tin whereas HMDT yielded\nphase-pure, stoichiometric BaSnO3 films. Significantly, HMDT resulted in\nphase-pure and stoichiometric BaSnO3 films even without the use of an oxygen\nplasma (i.e., with molecular oxygen alone). These results are discussed using\nthe ability of HMDT to form tin radicals and therefore, assisting with Sn to\nSn4+ oxidation reaction. Structural and electronic transport properties of\nfilms grown using HMDT with and without oxygen plasma are compared. This study\nprovides guideline for the choice of precursors that will enable synthesis of\nmetal oxides containing hard-to-oxidize metals using reactive radicals in MBE."
    },
    {
        "anchor": "Non-collinear magnetic ordering in compressed FePd$_3$ ordered alloy: a\n  first principles study: By means of ab initio calculations based on the density functional theory we\ninvestigated magnetic phase diagram of ordered FePd$_3$ alloy as a function of\nexternal pressure.\n  Considering several magnetic configurations we concluded that the system\nunder pressure has a tendency to non-collinear spin alignment. Analysis of the\nHeisenberg exchange parameters $J_{ij}$ revealed strong dependence of iron-iron\nmagnetic couplings on polarization of Pd atoms. To take into account the latter\neffect we built an extended Heisenberg model with higher order (biquadratic)\nterms. Minimizing the energy of this Hamiltonian, fully parameterized using the\nresults of ab initio calculations, we found a candidate for a ground state of\ncompressed FePd$_3$, which can be seen as two interpenetrating \"triple-Q\"\nphases.",
        "positive": "Consequences of niobium doping for the ferromagnetism and microstructure\n  of anatase Co: TiO2 films: It is shown that dilute niobium doping has significant effect on the\nferromagnetism and microstructure of dilutely cobalt-doped anatase TiO2 films.\nEpitaxial films of anatase TiO2 with 3% Co, without and with 1% niobium doping\nwere grown by pulsed-laser deposition at 875 C at different oxygen pressures.\nFor growth at 10^{-5} Torr niobium doping suppresses the ferromagnetism, while\nit enhances the same in films grown at 10^{-4} Torr. High-resolution Z-contrast\nScanning Transmission Electron Microscopy and Electron Energy Loss Spectroscopy\nshow uniform surface segregation of cobalt-rich Ti_{1-x-y}Co_{x}Nb_{y}O_{2-d}\nphase, but without cobalt metal clusters."
    },
    {
        "anchor": "Microscopic correlation between chemical and electronic states in\n  epitaxial graphene on SiC(000-1): We present energy filtered electron emission spectromicroscopy with spatial\nand wave-vector resolution on few layer epitaxial graphene on SiC$(000-1) grown\nby furnace annealing. Low energy electron microscopy shows that more than 80%\nof the sample is covered by 2-3 graphene layers. C1s spectromicroscopy provides\nan independent measurement of the graphene thickness distribution map. The work\nfunction, measured by photoelectron emission microscopy (PEEM), varies across\nthe surface from 4.34 to 4.50eV according to both the graphene thickness and\nthe graphene-SiC interface chemical state. At least two SiC surface chemical\nstates (i.e., two different SiC surface structures) are present at the\ngraphene/SiC interface. Charge transfer occurs at each graphene/SiC interface.\nK-space PEEM gives 3D maps of the k_|| pi - pi* band dispersion in micron scale\nregions show that the Dirac point shifts as a function of graphene thickness.\nNovel Bragg diffraction of the Dirac cones via the superlattice formed by the\ncommensurately rotated graphene sheets is observed. The experiments underline\nthe importance of lateral and spectroscopic resolution on the scale of future\nelectronic devices in order to precisely characterize the transport properties\nand band alignments.",
        "positive": "The temperature-dependence of carrier mobility is not a reliable\n  indicator of the dominant scattering mechanism: The temperature dependence of experimental charge carrier mobility is\ncommonly used as a predictor of the dominant carrier scattering mechanism in\nsemiconductors, particularly in thermoelectric applications. In this work, we\ncritically evaluate whether this practice is well founded. A review of 47\nstate-of-the-art mobility calculations reveals no correlation between the major\nscattering mechanism and the temperature trend of mobility. Instead, we\ndemonstrate that the phonon frequencies are the prevailing driving forces\nbehind the temperature dependence and can cause it to vary between $T^{-1}$ to\n$T^{-3}$ even for an idealised material. To demonstrate this, we calculate the\nmobility of 23,000 materials and review their temperature dependence, including\nseparating the contributions from deformation, polar, and impurity scattering\nmechanisms. We conclusively demonstrate that a temperature dependence of\n$T^{-1.5}$ is not a reliable indicator of deformation potential scattering. Our\nwork highlights the potential pitfalls of predicting the major scattering type\nbased on the experimental mobility temperature trend alone."
    },
    {
        "anchor": "Focused ion beam preparation of atom probe specimens containing a single\n  crystallographically well-defined grain boundary: Needle-shaped atom probe specimens containing a single grain boundary were\nproduced using the focused ion beam (FIB) of a dual-beam FIB/SEM (scanning\nelectron microscope) system. The presented specimen preparation approach allows\nthe unprecedented study of a grain boundary which is well characterised in its\ncrystallographic orientation by means of the field ion microscope (FIM) and the\ntomographic atom probe (TAP). The analysis of such specimens allows in\nparticular the determination of solute excess atoms at this specific grain\nboundary and hence the investigation of the segregation behaviour. The crucial\npreparation steps are discussed in detail in the present study for the S 19a\n{331} <110> grain boundary of a 40 at.ppm-Bi doped Cu bi-crystal. Transmission\nelectron microscope (TEM) images and TAP analyses of the atom probe tips\ndemonstrate unambiguously the presence of the selectively prepared grain\nboundary in the apex region of some of the specimens.",
        "positive": "Stress-sign-tunable Poisson's Ratio in Monolayer Blue Phosphorus Oxide: Negative Poisson's ratio (NPR) materials have attracted tremendous interest\ndue to their unusual physical properties and potential applications. Certain\ntwo-dimensional (2D) monolayer materials have also been found to exhibit NPR\nand the corresponding deformation mechanism varies. In this study, we found,\nbased on first-principles calculations, that the Poisson's ratio (PR) sign of\nmonolayer Blue Phosphorus Oxide (BPO) can be tuned by strain: the PR is\npositive under uniaxial strain <= -1% but becomes negative under > 0. The\ndeformation mechanism for BPO under strain depends on the mutual competition\nbetween the P-P attraction and P-O repulsion effect, and these two factors\ninduce two different deformation pathways (one with positive PR, and the other\nwith NPR). Moreover, with increasing of strain, both the decreased strength of\nP-P attraction and the increased strength of P-O repulsion effect modulate the\nPR of BPO from positive to negative."
    },
    {
        "anchor": "Electronic structure of $2H$-NbSe$_2$ single-layers in the CDW state: A density functional theory study of NbSe$_2$ single-layers in the normal\nnon-modulated and the $3\\times3$ CDW states is reported. We show that, in the\nsingle layer, the CDW barely affects the Fermi surface of the system, thus\nruling out a nesting mechanism as the driving force for the modulation. The CDW\nstabilizes levels lying around 1.5 eV below the Fermi level within the Se-based\nvalence band but having a substantial Nb-Nb bonding character. The absence of\ninterlayer interactions leads to the suppression of the pancake-like portion of\nthe bulk Fermi surface in the single-layer. We perform scanning tunneling\nmicroscopy simulations and find that the images noticeably change with the sign\nand magnitude of the voltage bias. The atomic corrugation of the Se sublayer\ninduced by the modulation plays a primary role in leading to these images, but\nthe electronic reorganization also has an important contribution. The analysis\nof the variation of these images with the bias voltage does not support a Fermi\nsurface nesting mechanism for the CDW. It is also shown that underlying\ngraphene layers (present in some of the recent experimental work) do not modify\nthe conduction band, but do affect the shape of the valence band of NbSe$_2$\nsingle-layers. The relevance of these results in understanding recent physical\nmeasurements for NbSe$_2$ single-layers is discussed.",
        "positive": "Microscopic origin of pressure-induced isosymmetric transitions in\n  fluoromanganate cryolites: Using first-principles density functional theory calculations, we investigate\nthe hydrostatic pressure-induced reorientation of the Mn--F Jahn-Teller bond\naxis in the fluoride cryolite Na$_3$MnF$_6$. We find a first-order isosymmetric\ntransition occurs between crystallographically equivalent monoclinic structures\nat approximately 2.15 GPa, consistent with earlier experimental studies.\nAnalogous calculations for isostructural $3d^0$ Na$_3$ScF$_6$ show no evidence\nof a transition up to 6.82 GPa. Mode crystallography analyses of the\npressure-dependent structures in the vicinity of the transition reveals a clear\nevolution of the Jahn-Teller bond distortions in cooperation with an\nasymmetrical stretching of the equatorial fluorine atoms in the MnF$_6$\noctahedral units. We identify a change in orbital occupancy of the $e_g$\nmanifold in the $3d^4$ Jahn-Teller active Mn(III) to be responsible for the\ntransition, which stabilizes one monoclinic $P2_1/n$ variant over the other."
    },
    {
        "anchor": "Nanotwinned diamond synthesized from multi-core onion carbon: Nano-polycrystalline diamond (NPD) and nanotwinned diamond (NtD) were\nsuccessfully synthesized in multi-anvil high pressure apparatus at high\npressure and high temperature (HPHT) conditions using precursors of onion\ncarbons. We found that the choices of distinct onion carbons with hollow or\nmulti-cored microstructures lead to the synthesis of different diamond products\nof NPD or NtD ones. High quality NtD with an average twin size of 6.8 nm has\nbeen synthesized whose Vickers hardness reaches as high as 180 GPa as measured\nby indentation hardness experiment. The existence of stacking faults other than\nvarious defects in the onion carbon is found to be crucial to form twin\nboundary in the product. The origin of the extraordinarily high Vickers\nhardness in the NtD sample is attributable to the high concentration of twin\nboundary. Our work gave a direct support on the argument that pursuit of\nnanotwinned microstructure is an effective strategy to harden materials, in\ngood coincidence with the well-known Hall-Petch effect.",
        "positive": "Fabrication and Characterization of an Amperometric Glucose Sensor on a\n  Flexible Polyimide Substrate: This study details the use of printing and other additive processes to\nfabricate a novel amperometric glucose sensor. The sensor was fabricated using\na Au coated 12.7 micron polyimide film as a starting material, where\nmicro-contact printing, electrochemical plating and chloridization,\nelectrohydrodynamic jet (e-jet) printing, and spin coating were used to\npattern, deposit, print, and coat functional materials, respectively. We have\nfound that e-jet printing was effective for the deposition and patterning of\nglucose oxidase inks between ~5 to 1000 micron in width, and we have\ndemonstrated that the enzyme was still active after printing. The thickness of\nthe permselective layer was optimized to obtain a linear response to glucose\nconcentration up to 32 mM. For these sensors no response to acetaminophen, a\ncommon interfering compound, was observed."
    },
    {
        "anchor": "Direct visualization of polaron formation in the thermoelectric SnSe: SnSe is a layered material that currently holds the record for bulk\nthermoelectric efficiency. The primary determinant of this high efficiency is\nthought to be the anomalously low thermal conductivity resulting from strong\nanharmonic coupling within the phonon system. Here we show that the nature of\nthe carrier system in SnSe is also determined by strong coupling to phonons by\ndirectly visualizing polaron formation in the material. We employ ultrafast\nelectron diffraction and diffuse scattering to track the response of phonons in\nboth momentum and time to the photodoping of free carriers across the bandgap,\nobserving the bimodal and anisotropic lattice distortions that drive carrier\nlocalization. Relatively large (\\SI{18.7}{\\angstrom}), quasi-1D polarons are\nformed on the \\SI{300}{\\femto\\second} timescale with smaller\n(\\SI{4.2}{\\angstrom}) 3D polarons taking an order of magnitude longer\n(\\SI{4}{\\pico\\second}) to form. This difference appears to be a consequence of\nthe profoundly anisotropic electron-phonon coupling in SnSe, with strong\nFr\\\"ohlich coupling only to zone center polar optical phonons. These results\ndemonstrate that carriers in SnSe at optimal doping levels results in a high\npolaron density and that strong electron-phonon coupling is also critical to\nthe thermoelectric performance of this benchmark material and potentially\nhigh-performance thermoelectrics more generally.",
        "positive": "Influence of defects on the electronic and magnetic properties of\n  half-metallic CrAs, CrSe and CrSb zinc-blende compounds: We present an extended study of single impurity atoms and atomic swaps in\nhalf-metallic CrAs, CrSb and CrSe zinc-blende compounds. Although the perfect\nalloys present a rather large gap in the minority-spin band, all defects under\nstudy, with the exception of void impurities at Cr and sp sites and Cr\nimpurities at sp sites (as long as no swap occurs), induce new states within\nthe gap. The Fermi level can be pinned within these new minority states\ndepending on the lattice constant used for the calculations and the\nelectronegativity of the sp atoms. Although these impurity states are localized\nin space around the impurity atoms and very fast we regain the bulk behavior,\ntheir interaction can lead to wide bands within the gap and thus loss of the\nhalf-metallic character."
    },
    {
        "anchor": "Cubic-scaling iterative solution of the Bethe-Salpeter equation for\n  finite systems: The Bethe-Salpeter equation (BSE) is currently the state of the art in the\ndescription of neutral electron excitations in both solids and large finite\nsystems. It is capable of accurately treating charge-transfer excitations that\npresent difficulties for simpler approaches. We present a local basis set\nformulation of the BSE for molecules where the optical spectrum is computed\nwith the iterative Haydock recursion scheme, leading to a low computational\ncomplexity and memory footprint. Using a variant of the algorithm we can go\nbeyond the Tamm-Dancoff approximation (TDA). We rederive the recursion\nrelations for general matrix elements of a resolvent, show how they translate\ninto continued fractions, and study the convergence of the method with the\nnumber of recursion coefficients and the role of different terminators. Due to\nthe locality of the basis functions the computational cost of each iteration\nscales asymptotically as $O(N^3)$ with the number of atoms, while the number of\niterations is typically much lower than the size of the underlying\nelectron-hole basis. In practice we see that , even for systems with thousands\nof orbitals, the runtime will be dominated by the $O(N^2)$ operation of\napplying the Coulomb kernel in the atomic orbital representation",
        "positive": "Quantum body in uniform magnetic fields: In this article it will be presented the first attempt made in order to\nperform gauge invariant calculations of eigenstates of a quantum body in its\ncondensed phase, the latter reacting to an external uniform magnetic field. The\ntarget is achieved introducing a new unitary translation operator transforming\neigenstates into a new set of eigenstates having different total linear\nmomentum. This new quantum representation solves the problem of calculating the\nmagnetic response of quantum eigenstates of finite or either infinite periodic\nsystems to uniform magnetic fields, where equivalence between the customarily\nused representation and the new representation has been made."
    },
    {
        "anchor": "Topological magnetic-spin textures in two-dimensional van der Waals\n  Cr2Ge2Te6: Two-dimensional (2D) van der Waals (vdW) materials show a range of profound\nphysical properties that can be tailored through their incorporation in\nheterostructures and manipulated with external forces. The recent discovery of\nlong-range ferromagnetic order down to atomic layers provides an additional\ndegree of freedom in engineering 2D materials and their heterostructure devices\nfor spintronics, valleytronics and magnetic tunnel junction switches. Here,\nusing direct imaging by cryo-Lorentz transmission electron microscopy we show\nthat topologically nontrivial magnetic-spin states, skyrmionic bubbles, can be\nrealized in exfoliated insulating 2D vdW Cr2Ge2Te6. Due to the competition\nbetween dipolar interactions and uniaxial magnetic anisotropy,\nhexagonally-packed nanoscale bubble lattices emerge by field cooling with\nmagnetic field applied along the out-of-plane direction. Despite a range of\ntopological spin textures in stripe domains arising due to pair formation and\nannihilation of Bloch lines, bubble lattices with single chirality are\nprevalent. Our observation of topologically-nontrivial homochiral skyrmionic\nbubbles in exfoliated vdW materials provides a new avenue for novel quantum\nstates in atomically-thin insulators for magneto-electronic and quantum\ndevices.",
        "positive": "Enhancement of spontaneous emission in a quantum well by resonant\n  surface plasmon coupling: Using time-resolved photoluminescence measurements, the recombination rate in\nan In$_{0.18}$Ga$_{0.82}$N/GaN quantum well (QW) is shown to be greatly\nenhanced when spontaneous emission is resonantly coupled to a silver surface\nplasmon. The rate of enhanced spontaneous emission into the surface plasmon was\nas much as 92 times faster than normal QW spontaneous emission. A calculation,\nbased on Fermi's golden rule, reveals the enhancement is very sensitive to\nsilver thickness and indicates even greater enhancements are possible for QWs\nplaced closer to the surface metal coating."
    },
    {
        "anchor": "Phenomenological analysis of densification mechanism during spark plasma\n  sintering of MgAl2O4: Spark plasma sintering (SPS) of MgAl2O4 powder was investigated at\ntemperatures between 1200 and 1300{\\deg}C. A significant grain growth was\nobserved during densification. The densification rate always exhibits at least\none strong minimum, and resumes after an incubation period. Transmission\nelectron microscopy investigations performed on sintered samples never revealed\nextensive dislocation activity in the elemental grains. The densification\nmechanism involved during SPS was determined by anisothermal (investigation of\nthe heating stage of a SPS run) and isothermal methods (investigation at given\nsoak temperatures). Grain-boundary sliding, accommodated by an in-series\n{interface-reaction/lattice diffusion of the O$^2$-anions} mechanism controlled\nby the interface-reaction step, governs densification. The\nzero-densification-rate period, detected for all soak temperatures, arise from\nthe difficulty of annealing vacancies, necessary for the densification to\nproceed. The detection of atomic ledges at grain boundaries and the\nmodification of the stoichiometry of spinel during SPS could be related to the\ndifficulty to anneal vacancies at temperature soaks.",
        "positive": "Ab initio study of 2p-core level x-ray photoemission spectra in\n  ferromagnetic transition metals: We study the 2p-core level x-ray photoemission spectra in ferromagnetic\ntransition metals, Fe, Co, and Ni using a recently developed ab initio\nmethod.The excited final states are set up by distributing electrons on the\none-electron states calculated under the fully screened potential in the\npresence of the core hole. We evaluate the overlap between these excited states\nand the ground state by using one-electron wave functions, and obtain the\nspectral curves as a function of binding energy. The calculated spectra\nreproduce well the observed spectra displaying interesting dependence on the\nelement and on the spin of the removed core electron. The origin of the\nspectral shapes is elucidated in terms of the one-electron states screening the\ncore hole. The magnetic splitting of the threshold energy is also estimated by\nusing the coherent potential approximation within the fully screened potential\napproximation. It decreases more rapidly than the local spin moment with moving\nfrom Fe to Ni. It is estimated to be almost zero for Ni despite the definite\nlocal moment about 0.6\\mu_B, in agreement with the experiment."
    },
    {
        "anchor": "Distinguishing different stackings in layered materials via luminescence\n  spectroscopy: Despite its simple crystal structure, layered boron nitride features a\nsurprisingly complex variety of phonon-assisted luminescence peaks. We present\na combined experimental and theoretical study on ultraviolet-light emission in\nhexagonal and rhombohedral bulk boron nitride crystals. Emission spectra of\nhigh-quality samples are measured via cathodoluminescence spectroscopy,\ndisplaying characteristic differences between the two polytypes. These\ndifferences are explained using a fully first-principles computational\ntechnique that takes into account radiative emission from ``indirect'',\nfinite-momentum, excitons via coupling to finite-momentum phonons. We show that\nthe differences in peak positions, number of peaks and relative intensities can\nbe qualitatively and quantitatively explained, once a full integration over all\nrelevant momenta of excitons and phonons is performed.",
        "positive": "Spin Seebeck effect in quantum magnet Pb2V3O9: Spin Seebeck effect (SSE), the generation of spin current from heat, has been\nextensively studied in a large variety of magnetic materials, including\nferromagnets, antiferromagnets, paramagnets, and quantum spin liquids. In this\npaper, we report the study of the SSE in the single crystalline Pb2V3O9, a\nspin-gapped quantum magnet candidate with quasi-one-dimensional spin-1/2 chain.\nDetailed temperature and magnetic field dependences of the SSE are\ninvestigated, and the temperature-dependent critical magnetic fields show a\nstrong correlation to the Bose-Einstein condensation phase of the quantum\nmagnet Pb2V3O9. This work shows the potential of using spin current as a probe\nto study the spin correlation and phase transition properties in quantum\nmagnets."
    },
    {
        "anchor": "Hybrid density functional calculations of the band gap of\n  Ga$_x$In$_{1-x}$N: Recent theoretical work has provided evidence that hybrid functionals, which\ninclude a fraction of exact (Hartree Fock) exchange in the density functional\ntheory (DFT) exchange and correlation terms, significantly improve the\ndescription of band gaps of semiconductors compared with local and semilocal\napproximations. Based on a recently developed order-$N$ method for calculating\nthe exact exchange in extended insulating systems, we have implemented an\nefficient scheme to determine the hybrid functional band gap. We use this\nscheme to study the band gap and other electronic properties of the ternary\ncompound In$_{1-x}$Ga$_{x}$N using a 64-atom supercell model.",
        "positive": "Engineering the polar magneto-optical Kerr effect in strongly strained\n  L10-MnAl films: We report the engineering of the polar magnetooptical (MO) Kerr effect in\nperpendicularly magnetized L10-MnAl epitaxial films with remarkably tuned\nmagnetization, strain, and structural disorder by varying substrate temperature\n(Ts) during molecular-beam epitaxy growth. The Kerr rotation was enhanced by a\nfactor of up to 5 with Ts increasing from 150 to 350 oC as a direct consequence\nof the improvement of the magnetization. A similar remarkable tuning effect was\nalso observed on the Kerr ellipticity and the magnitude of the complex Kerr\nangle, while the phase of the complex Kerr angle appears to be independent of\nthe magnetization. The combination of the good semiconductor compatibility, the\nmoderate coercivity of 0.3-8.2 kOe, the tunable polar MO Kerr effect of up to\n~0.034o, and giant spin procession frequencies of up to ~180 GHz makes L10-MnAl\nfilms a very interesting MO material. Our results give insights on both the\nmicroscopic mechanisms of the MO Kerr effect in L10-MnAl alloys and their\nscientific and technological application potential in the emerging spintronics\nand ultrafast MO modulators."
    },
    {
        "anchor": "Deep Learning and Density Functional Theory: We show that deep neural networks can be integrated into, or fully replace,\nthe Kohn-Sham density functional theory scheme for multi-electron systems in\nsimple harmonic oscillator and random external potentials with no feature\nengineering. We first show that self-consistent charge densities calculated\nwith different exchange-correlation functionals can be used as input to an\nextensive deep neural network to make predictions for correlation, exchange,\nexternal, kinetic and total energies simultaneously. Additionally, we show that\none can also make all of the same predictions with the external potential\nrather than the self-consistent charge density, which allows one to circumvent\nthe Kohn-Sham scheme altogether. We then show that a self-consistent charge\ndensity found from a non-local exchange-correlation functional can be used to\nmake energy predictions for a semi-local exchange-correlation functional.\nLastly, we use a deep convolutional inverse graphics network to predict the\ncharge density given an external potential for different exchange-correlation\nfunctionals and assess the viability of the predicted charge densities. This\nwork shows that extensive deep neural networks are generalizable and\ntransferable given the variability of the potentials (maximum total energy\nrange $\\approx100$ Ha), because they require no feature engineering, and\nbecause they can scale to an arbitrary system size with an $\\mathcal{O}(N)$\ncomputational cost.",
        "positive": "Enhancement of SHG efficiency by urea doping in ZTS single crystals and\n  its correlation with crystalline perfection revealed by Kurtz powder and\n  high-resolution X-ray diffraction methods: Enhancement of second harmonic generation (SHG) efficiency and the\ncorrelation between crystalline perfection and SHG with urea doping on\ntristhioureazinc(II) sulphate (ZTS) single crystals have been investigated. ZTS\nis a potential semiorganic nonlinear optical (NLO) material. Pure and urea\ndoped single crystals of ZTS have been successfully grown by slow evaporation\nsolution technique (SEST). Presence of dopants has been confirmed and analyzed\nby Fourier transform infrared (FTIR) spectrometer. The influence of urea doping\nat different concentrations on the crystalline perfection has been thoroughly\nassessed by high resolution X-ray diffractometry (HRXRD). HRXRD studies\nrevealed that the crystals could accomodate urea in ZTS up to some critical\nconcentration without any deterioration in the crystalline perfection. Above\nthis concentration, very low angle structural grain boundaries were developed\nand it seems, the excess urea above the critical concentration was segregated\nalong the grain boundaries. At very high doping concentrations, the crystals\nwere found to contain mosaic blocks. The SHG effeiciency has been studied by\nusing Kurtz powder technique. The relative SHG efficiency of the crystals was\nfound to be increased substantially with the increase of urea concentration.\nThe correlation found between the crystalline perfection and SHG efficiency was\ndiscussed."
    },
    {
        "anchor": "Strain-induced quantum topological phase transitions in Na3Bi: Strain can be used as an effective tool to tune the crystal structure of\nmaterials and hence to modify their electronic structures, including\ntopological properties. Here, taking Na3Bi as a paradigmatic example, we\ndemonstrated with first-principles calculations and k$\\cdot$p models that the\ntopological phase transitions can be induced by various types of strains. For\ninstance, the Dirac semimetal phase of ambient Na3Bi can be tuned into a\ntopological insulator (TI) phase by uniaxial strain along the h100i axis.\nHydrostatic pressure can let the ambient structure transfer into a new\nthermodynamically stable phase with Fm-3m symmetry, coming with a perfect\nparabolic semimetal having a single contact point between the conduction and\nvalence bands, exactly at $\\Gamma$ point on the Fermi level like $\\alpha$-Sn.\nFurthermore, uniaxial strain in the <100> direction can tune the new parabolic\nsemimetal phase into a Dirac semimetal, while shear strains in both the <100>\nand <111> directions can take the new parabolic semimetal phase into a TI.\nk$\\cdot$p models are constructed to gain more insights into these quantum\ntopological phase transitions. At last, we calculated surface states of Fm-3m\nNa3Bi without and with strains to verify these topological transitions.",
        "positive": "Elastic, electronic and magnetic properties of new oxide perovskite\n  BaVO3: a first-principles study: The structural, elastic, magnetic properties, as well as electronic structure\nand chemical bonding picture of new oxide 3d1-perovskite BaVO3, recently\nsynthesized, were systematically investigated involving the first-principles\nFLAPW-GGA calculations. The obtained results are discussed in comparison with\navailable experimental data, as well as with those obtained before for\nisostructural and isoelectronic SrVO3 perovskite."
    },
    {
        "anchor": "Comment on \"Application of the Lifshitz theory to poor conductors\"\n  [arXiv:0809.3901]: Recent Letter by V. B. Svetovoy [Phys. Rev. Lett. v.101, 163603 (2008),\narXiv:0809.3901] claims that the Lifshitz theory combined with spatially\nnonlocal dielectric permittivities is consistent with the experimental data and\nNernst's theorem. We prove that these claims are incorrect. They are based on\nirregular comparison with the data and misinterpretation of relevant physical\nquantities.",
        "positive": "Ferromagnetism in (In,Mn)As Diluted Magnetic Semiconductor Thin Films\n  Grown by Metalorganic Vapor Phase Epitaxy: In1-xMnxAs diluted magnetic semiconductor (DMS) thin films have been grown\nusing metalorganic vapor phase epitaxy (MOVPE).\nTricarbonyl(methylcyclopentadienyl)manganese was used as the Mn source.\nNominally single-phase, epitaxial films were achieved with Mn content as high\nas x=0.14 using growth temperatures Tg>475 C. For lower growth temperatures and\nhigher Mn concentrations, nanometer scale MnAs precipitates were detected\nwithin the In1-xMnxAs matrix. Magnetic properties of the films were\ninvestigated using a superconducting quantum interference device (SQUID)\nmagnetometer. Room-temperature ferromagnetic order was observed in a sample\nwith x=0.1. Magnetization measurements indicated a Curie temperature of 333 K\nand a room-temperature saturation magnetization of 49 emu/cm^3. The remnant\nmagnetization and the coercive field were small, with values of 10 emu/cm^3 and\n400 Oe, respectively. A mechanism for this high-temperature ferromagnetism is\ndiscussed in light of the recent theory based on the formation of small\nclusters of a few magnetic atoms."
    },
    {
        "anchor": "Ab-inito study of low temperature magnetic properties of double\n  perovskite Sr2FeOsO6: Using density-functional theory calculations, we investigated the electronic\nstructure and magnetic exchange interactions of the ordered 3d-5d double\nperovskite Sr2FeOsO6, which has recently drawn attention for interesting\nantiferromagnetic transitions. Our study reveals the vital role played by\nlong-range magnetic exchange interactions in this compound. The competition\nbetween the ferromagnetic nearest neighbor Os-O-Fe interaction and\nantiferromagnetic next nearest neighbor Os-O-Fe-O-Os interaction induces strong\nfrustration in this system, which explains the lattice distortion and magnetic\nphase transitions observed in experiments.",
        "positive": "Revealing the impact of polystyrene-functionalization of Au octahedral\n  nanocrystals of different sizes on formation and structure of mesocrystals: The self-assembly of anisotropic nanocrystals (stabilized by organic capping\nmolecules) with pre-selected composition, size, and shape allows for the\ncreation of nanostructured materials with unique structures and features. For\nsuch a material, the shape and packing of the individual nanoparticles play an\nimportant role. This work presents a synthesis procedure for\n{\\omega}-thiol-terminated polystyrene (PS-SH) functionalized gold nanooctahedra\nof variable size (edge length 37, 46, 58, and 72 nm). The impact of polymer\nchain length (Mw: 11k, 22k, 43k, and 66k g/mol) on the growth of colloidal\ncrystals (e.g. mesocrystals) and their resulting crystal structure is\ninvestigated. Small-angle X-ray scattering (SAXS) and scanning transmission\nelectron microscopy (STEM) methods provide a detailed structural examination of\nthe self-assembled faceted mesocrystals based on octahedral gold nanoparticles\nof different size and surface functionalization. Three-dimensional angular\nX-ray cross-correlation analysis (AXCCA) enables high-precision determination\nof the superlattice structure and relative orientation of nanoparticles in\nmesocrystals. This approach allows us to perform non-destructive\ncharacterization of mesocrystalline materials and reveals their structure with\nresolution down to the nanometer scale."
    },
    {
        "anchor": "Generalized Algorithm for Recognition of Complex Point Defects in\n  Large-Scale \u03b2-$\\rm {Ga_2O_3}$: The electrical and optical properties of semiconductor materials are\nprofoundly influenced by the atomic configurations and concentrations of\nintrinsic defects. This influence is particularly significant in the case of\n$\\beta$-$\\rm {Ga_2O_3}$, a vital ultrawide bandgap semiconductor characterized\nby highly complex intrinsic defect configurations. Despite its importance,\nthere is a notable absence of an accurate method to recognize these defects in\nlarge-scale atomistic computational modeling. In this work, we present an\neffective algorithm designed explicitly for identifying various intrinsic point\ndefects in the $\\beta$-$\\rm {Ga_2O_3}$ lattice. By integrating particle swarm\noptimization and hierarchical clustering methods, our algorithm attains a\nrecognition accuracy exceeding 95% for discrete point defect configurations.\nFurthermore, we have developed an efficient technique for randomly generating\ndiverse intrinsic defects in large-scale $\\beta$-$\\rm {Ga_2O_3}$ systems. This\napproach facilitates the construction of an extensive atomic database,\ncrucially instrumental in validating the recognition algorithm through a\nsubstantial number of statistical analyses. Finally, the recognition algorithm\nis applied to a molecular dynamics simulation, accurately describing the\nevolution of the point defects during high-temperature annealing. Our work\nprovides a useful tool for investigating the complex dynamical evolution of\nintrinsic point defects in $\\beta$-$\\rm {Ga_2O_3}$, and moreover, holds promise\nfor understanding similar material systems, such as $\\rm {Al_2O_3}$, $\\rm\n{In_2O_3}$, and $\\rm {Sb_2O_3}$.",
        "positive": "Thickness monitoring of graphene on SiC using low-energy electron\n  diffraction: The formation of epitaxial graphene on SiC is monitored in-situ using\nlow-energy electron diffraction (LEED). The possibility of using LEED as an\nin-situ thickness monitor of the graphene is examined. The ratio of primary\ndiffraction spot intensities for graphene compared to SiC is measured for a\nseries of samples of known graphene thickness (determined using low-energy\nelectron microscopy). It is found that this ratio is effective for determining\ngraphene thicknesses in the range 1 to 3 monolayers. Effects of a distribution\nof graphene thicknesses on this method of thickness determination are\nconsidered."
    },
    {
        "anchor": "Magnetism in MoS2 induced by MeV proton irradiation: Molybdenum disulphide, a diamagnetic layered dichalcogenide solid, is found\nto show magnetic ordering at room temperature when exposed to a 2 MeV proton\nbeam. The temperature dependence of magnetization displays ferrimagnetic\nbehavior with a Curie temperature of 895 K. A disorder mode corresponding to a\nzone-edge phonon and a Mo valence higher than +4, have been detected in the\nirradiated samples using Raman and X-ray photoelectron spectroscopy,\nrespectively. The possible origins of long-range magnetic ordering in\nirradiated MoS2 samples are discussed.",
        "positive": "Magnetoresistive Sensor Detectivity: A Comparative Analysis: We report on the noise performance characteristics of magnetic sensors using\nboth magnetic tunnel junction (MTJ) and giant magnetoresistance (GMR) elements.\nEach sensor studied has a notably different noise and detectivity. Of the\nsensors we measured, those based on GMR multilayers have the lowest noise and\ndetectivity. However, the GMR sensor also has a significantly smaller linear\nrange. To make a direct comparison between sensors we scale the linear\noperating ranges of each sensor to be the same. This is the phenomenological\nequivalent of modifying the flux concentration. Upon scaling the low frequency\ndetectivity of the TMR sensors becomes essentially equal to that of the GMR\nsensor. Using the scaling approach we are able to place the detectivity in the\ncontext of other key parameters, namely size and power consumption. Lastly, we\nuse this technique to examine the upper limit for magnetoresistive sensor\nperformance based on a notional MTJ sensor using present record setting TMR\nvalues."
    },
    {
        "anchor": "Structural and magnetic phase transitions in EuTi1-xNbxO3: We investigate the structural and magnetic phase transitions in EuTi1-xNbxO3\nwith synchrotron powder X-ray diffraction (XRD), resonant ultrasound\nspectroscopy (RUS), and magnetization measurements. Upon Nb-doping, the Pm-3m\nto I4/mcm structural transition shifts to higher temperatures and the room\ntemperature lattice parameter increases while the magnitude of the octahedral\ntilting decreases. In addition, Nb substitution for Ti destabilizes the\nantiferromagnetic ground state of the parent compound and long range\nferromagnetic order is observed in the samples containing more than 10% Nb. The\nstructural transition in pure and doped compounds is marked by a step-like\nsoftening of the elastic moduli in a narrow temperature interval near TS, which\nresembles that of SrTiO3 and can be adequately modeled using the Landau free\nenergy model employing the same coupling between strain and octahedral tilting\norder parameter as previously used to model SrTiO3.",
        "positive": "Topological transport in Dirac electronic systems: A concise review: Various novel physical properties have emerged in Dirac electronic systems,\nespecially the topological characters protected by symmetry. Current studies on\nthese systems have been greatly promoted by the intuitive concepts of Berry\nphase and Berry curvature, which provide precise definitions of the topological\norders. In this topical review, transport properties of topological insulator\n(Bi2Se3), topological Dirac semimetal (Cd3As2) and topological\ninsulator-graphene heterojunction are presented and discussed. Perspectives\nabout transport properties of two-dimensional topological nontrivial systems,\nincluding topological edge transport, topological valley transport and\ntopological Weyl semimetals, are provided."
    },
    {
        "anchor": "Strain-Induced Room-Temperature Ferromagnetic Semiconductors with Large\n  Anomalous Hall Conductivity in Two-Dimensional Cr2Ge2Se6: By density functional theory calculations, we predict a stable\ntwo-dimensional (2D) ferromagnetic semiconductor Cr$_2$Ge$_2$Se$_6$, where the\nCurie temperature $T$$_c$ can be dramatically enhanced beyond room temperature\nby applying a few percent strain. In addition, the anomalous Hall conductivity\nin 2D Cr$_2$Ge$_2$Se$_6$ and Cr$_2$Ge$_2$Te$_6$ is predicted to be comparable\nto that in ferromagnetic metals of Fe and Ni, and is an order of magnitude\nlarger than that in diluted magnetic semiconductor Ga(Mn,As). Based on\nsuperexchange interactions, the enhanced $T$$_c$ in 2D Cr$_2$Ge$_2$Se$_6$ by\nstrain can be understood by the decreased energy difference between 3$d$\norbitals of Cr and 4$p$ orbitals of Se. Our finding highlights the microscopic\nmechanism to obtain the room temperature ferromagnetic semiconductors by\nstrain.",
        "positive": "Scattering of antiplane elastic waves by two-dimensional periodic arrays\n  of cracks: In the context of elastic wave propagation in damaged solids, an analytical\napproach for scattering of antiplane waves by two-dimensional periodic arrays\nof cracks is developed. Before considering the study of arrays of cracks, the\nscattering of an antiplane wave by a flat crack is first studied. Then, using\nthe representation formula for the scattered displacement by a flat and by\nconsidering the periodicity condition of the crack-spacing, a boundary integral\nequation is obtained for the crack face displacement of the reference crack.\nNumerical results for the reflection and transmission coefficients are\npresented as functions of the crack-spacing, the frequency of excitation, and\nthe angle of incidence. Finally, the propagation of antiplane waves by\ntwo-dimensional periodic arrays of cracks is studied. Despite the use of a\nfinite number of linear arrays, one recognizes the effects of band-pass\nfiltering or band rejection characteristics of the transmission spectra of a\nperiodic medium. Effects due to a disorder in the periodicity are also\nanalysed."
    },
    {
        "anchor": "Plasmons dispersion and nonvertical interband transitions in\n  single-crystal Bi2Se3 investigated by electron energy loss spectroscopy: Plasmons dispersion and nonvertical interband transitions in Bi2Se3 single\ncrystals were investigated by electron energy-loss spectroscopy in conjunction\nwith (scanning) transmission electron microscopy, (S)TEM-EELS. Both volume\nplasmons ({\\pi} plasmon at 7 eV and {\\pi}+{\\sigma} plasmon at 17 eV) and\nsurface plasmons (~5.5 and 10 eV) were demonstrated in STEM-EELS spectra and\nthe corresponding spectral imaging in real space. In the further EELS\nexperiments in reciprocal space, the momentum-dependent spectra reveal very\ndifferent dispersion behavior between {\\pi} and {\\pi}+{\\sigma} plasmons, with\n{\\pi}+{\\sigma} plasmons showing a typical quadratic dependence whereas the\n{\\pi} plasmon exhibiting a linear dispersion analogous to what was reported for\ngraphene. Furthermore, a low energy excitation 0.7~1.6 eV was also observed\nwhich is attributed to direct nonvertical interband transitions along the\ngamma-F direction.",
        "positive": "The continuum elastic and atomistic viewpoints on the formation volume\n  and strain energy of a point defect: We discuss the roles of continuum linear elasticity and atomistic\ncalculations in determining the formation volume and the strain energy of\nformation of a point defect in a crystal. Our considerations bear special\nrelevance to defect formation under stress. The elasticity treatment is based\non the Green's function solution for a center of contraction or expansion in an\nanisotropic solid. It makes possible the precise definition of a formation\nvolume tensor and leads to an extension of Eshelby's result for the work done\nby an external stress during the transformation of a continuum inclusion (Proc.\nRoy. Soc. Lond. Ser. A, 241 (1226) 376, 1957). Parameters necessary for a\ncomplete continuum calculation of elastic fields around a point defect are\nobtained by comparing with an atomistic solution in the far field. However, an\nelasticity result makes it possible to test the validity of the formation\nvolume that is obtained via atomistic calculations under various boundary\nconditions. It also yields the correction term for formation volume calculated\nunder these boundary conditions. Using two types of boundary conditions\ncommonly employed in atomistic calculations, a comparison is also made of the\nstrain energies of formation predicted by continuum elasticity and atomistic\ncalculations. The limitations of the continuum linear elastic treatment are\nrevealed by comparing with atomistic calculations of the formation volume and\nstrain energies of small crystals enclosing point defects."
    },
    {
        "anchor": "Atom-by-Atom Substitution of Mn in GaAs and Visualization of their\n  Hole-Mediated Interactions: The discovery of ferromagnetism in Mn doped GaAs [1] has ignited interest in\nthe development of semiconductor technologies based on electron spin and has\nled to several proof-of-concept spintronic devices [2-4]. A major hurdle for\nrealistic applications of (Ga,Mn)As, or other dilute magnetic semiconductors,\nremains their below room-temperature ferromagnetic transition temperature.\nEnhancing ferromagnetism in semiconductors requires understanding the\nmechanisms for interaction between magnetic dopants, such as Mn, and\nidentifying the circumstances in which ferromagnetic interactions are maximized\n[5]. Here we report the use of a novel atom-by-atom substitution technique with\nthe scanning tunnelling microscope (STM) to perform the first controlled atomic\nscale study of the interactions between isolated Mn acceptors mediated by the\nelectronic states of GaAs. High-resolution STM measurements are used to\nvisualize the GaAs electronic states that participate in the Mn-Mn interaction\nand to quantify the interaction strengths as a function of relative position\nand orientation. Our experimental findings, which can be explained using\ntight-binding model calculations, reveal a strong dependence of ferromagnetic\ninteraction on crystallographic orientation. This anisotropic interaction can\npotentially be exploited by growing oriented Ga1-xMnxAs structures to enhance\nthe ferromagnetic transition temperature beyond that achieved in randomly doped\nsamples. Our experimental methods also provide a realistic approach to create\nprecise arrangements of single spins as coupled quantum bits for memory or\ninformation processing purposes.",
        "positive": "Analysis of Reflection Electron Energy Loss Spectra (REELS) for\n  Determination of the Dielectric Function of Solids: Fe, Co, Ni: A simple procedure is developed to simultaneously eliminate multiple\nscattering contributions from two reflection electron energy loss spectra\n(REELS) measured at different energies or for different experimental\ngeometrical configurations. The procedure provides the differential inverse\ninelastic mean free path (DIIMFP) and the differential surface excitation\nprobability (DSEP). The only required input parameters are the differential\ncross section for elastic scattering and a reasonable estimate for the\ninelastic mean free path (IMFP). No prior information on surface excitations is\nrequired for the deconvolution. The retrieved DIIMFP and DSEP can be used to\ndetermine the dielectric function of a solid by fitting the DSEP and DIIMFP to\ntheory. Eventually, the optical data can be used to calculate the (differential\nand total) inelastic mean free path and the surface excitation probability. The\nprocedure is applied to Fe, Co and Ni and the retrieved optical data as well as\nthe inelastic mean free paths and surface excitation parameters derived from it\nare compared to values reported earlier in the literature. In all cases,\nreasonable agreement is found between the present data and the earlier results,\nsupporting the validity of the procedure."
    },
    {
        "anchor": "Single photon emitters based on Ni/Si related defects in single\n  crystalline diamond: We present investigations on single Ni/Si related color centers produced via\nion implantation into single crystalline type IIa CVD diamond. Testing\ndifferent ion dose combinations we show that there is an upper limit for both\nthe Ni and the Si dose 10^12/cm^2 and 10^10/cm^2 resp.) due to creation of\nexcess fluorescent background. We demonstrate creation of Ni/Si related centers\nshowing emission in the spectral range between 767nm and 775nm and narrow\nline-widths of 2nm FWHM at room temperature. Measurements of the intensity\nauto-correlation functions prove single-photon emission. The investigated color\ncenters can be coarsely divided into two groups: Drawing from photon statistics\nand the degree of polarization in excitation and emission we find that some\ncolor centers behave as two-level, single-dipole systems whereas other centers\nexhibit three levels and contributions from two orthogonal dipoles. In\naddition, some color centers feature stable and bright emission with saturation\ncount rates up to 78kcounts/s whereas others show fluctuating count rates and\nthree-level blinking.",
        "positive": "Solid phase of Krypton on the exterior of individual single-walled\n  carbon nanotubes: We have computed the adsorption of Krypton in a closed single-walled carbon\nnanotube using the method of Grand Canonical Monte Carlo. Our results indicate\nevidence of an incommensurate solid formed at high pressure and low temperature\n(T<85K), before the formation of a second layer. The solid melts above that\ntemperature. Our simulations are in good agreement with novel experimental\nresults for adsorption in individual carbon nanotubes."
    },
    {
        "anchor": "Auxetic Black Phosphorus: A 2D Material with Negative Poisson's Ratio: The Poisson's ratio of a material characterizes its response to uniaxial\nstrain. Materials normally possess a positive Poisson's ratio - they contract\nlaterally when stretched, and expand laterally when compressed. A negative\nPoisson's ratio is theoretically permissible but has not, with few exceptions\nof man-made bulk structures, been experimentally observed in any natural\nmaterials. Here, we show that the negative Poisson's ratio exists in the\nlow-dimensional natural material black phosphorus, and that our experimental\nobservations are consistent with first principles simulations. Through\napplication of uniaxial strain along zigzag and armchair directions, we find\nthat both interlayer and intralayer negative Poisson's ratios can be obtained\nin black phosphorus. The phenomenon originates from the puckered structure of\nits in-plane lattice, together with coupled hinge-like bonding configurations.",
        "positive": "Machine-Learning Accelerated Annealing with Fitting-Search Style for\n  Multi-alloy Structure Predictions: Structural prediction for the discovery of novel materials is a long sought\nafter goal of computational physics and materials sciences. The success is\nrather limited for methods such as the simulated annealing method (SA) that\nrequire expensive density functional theory (DFT) calculations and follow\nunintelligent search paths. Here a machine-learning based crystal combinatorial\noptimization program (CCOP) with a fitting-search style is proposed to\ndrastically improve the efficiency of structural search in SA. CCOP uses a\ngraph neural network energy prediction model to reduce the DFT cost and a deep\nreinforcement learning algorithm to direct the search path. Tests on six\nmulti-alloys show the energy prediction model is capable of extracting the\nbonding characteristics of the complex alloys to achieve interpretability. It\nalso achieves high accuracy with a tiny training set (an increment of 30\nsamples per iteration) by active learning in less than 5 iterations. Comparison\nwith a few conventional methods shows that CCOP finds the lowest-energy\nstructures with the smallest number of search steps. CCOP cuts the computing\ncost of SA by two orders of magnitude, while providing better search results\nthan SA. CCOP is promising for serving as a broadly applicable tool for the\nefficient crystal structure predictions."
    },
    {
        "anchor": "Densities of States, Moments, and Maximally Broken Time-Reversal\n  Symmetry: Power moments, modified moments, and optimized moments are powerful tools for\nsolving microscopic models of macroscopic systems; however the expansion of the\ndensity of states as a continued fraction does not converge to the macroscopic\nlimit point-wise in energy with increasing numbers of moments. In this work the\nmoment problem is further constrained by minimal lifetimes or maximal breaking\nof time-reversal symmetry, to yield approximate densities of states with\npoint-wise macroscopic limits. This is applied numerically to models with one\nand two finite bands with various singularities, as well as to a model with\ninfinite band-width, and the results are compared with the maximum entropy\napproximation where possible.",
        "positive": "The role of Ce$^{3+}$/Ce$^{4+}$ in the spectroscopic properties of\n  cerium oxide doped zinc-tellurite glasses prepared under air: Emerging technologies are demanding innovative properties of glasses. In this\nwork, Cerium Oxide is used as a dopant in Zinc-Tellurite samples and its\neffects on the properties of the glass are investigated. Thermal analysis and\nx-ray diffraction confirmed the amorphous nature of all samples. The bivalent\nnature of Cerium is investigated spectroscopically and a strong redshift\ninduced by the dopant is attributed to charge transfers\nO$^{2-}{\\rightarrow}$Ce$^{4+}$, while the 4f-5d transition of Ce$^{3+}$ could\nnot be identified in absorption or luminescence measurements. Yellow/red\n(570/650 nm) emission under 405/450 nm pumping were observed and are originated\nfrom Te$^{4+}$ ions, which absorbs light in the UV/blue region of the spectrum.\nThe incorporation of some Cerium Oxide enhanced the visible luminescence,\nthough we found no evidence that Cerium ions play some role in the radiative\nprocess. The luminescence is enhanced though due changes in the glass network\ninduced by the dopant."
    },
    {
        "anchor": "What dictates soft clay-like Lithium superionic conductor formation from\n  rigid-salts mixture: Soft clay-like Li-superionic conductors have been recently synthesized by\nmixing rigid-salts. Through computational and experimental analysis, we clarify\nhow a soft clay-like material can be created from a mixture of rigid-salts.\nUsing molecular dynamics simulations with a deep learning-based interatomic\npotential energy model, we uncover the microscopic features responsible for\nsoft clay-formation from ionic solid mixtures. We find that salt mixtures\ncapable of forming molecular solid units on anion exchange, along with the slow\nkinetics of such reactions, are key to soft-clay formation. Molecular solid\nunits serve as sites for shear transformation zones, and their inherent\nsoftness enables plasticity at low stress. Extended X-ray absorption fine\nstructure spectroscopy confirms the formation of molecular solid units. A\ngeneral strategy for creating soft clay-like materials from ionic solid\nmixtures is formulated.",
        "positive": "Anisotropy in the electronic structure of V2GeC investigated by soft\n  x-ray emission spectroscopy and first-principles theory: The anisotropy of the electronic structure of ternary nanolaminate V2GeC is\ninvestigated by bulk-sensitive soft x-ray emission spectroscopy. The measured\npolarization-dependent emission spectra of V L2,3, C K, Ge M1 and Ge M2,3 in\nV2GeC are compared to those from monocarbide VC and pure Ge. The experimental\nemission spectra are interpreted with calculated spectra using ab initio\ndensity-functional theory including dipole transition matrix elements.\nDifferent types of covalent chemical bond regions are revealed; V 3d - C 2p\nbonding at -3.8 eV, Ge 4p - C 2p bonding at -6 eV and Ge 4p - C 2s interaction\nmediated via the V 3d orbitals at -11 eV below the Fermi level. We find that\nthe anisotropic effects are high for the 4p valence states and the shallow 3d\ncore levels of Ge, while relatively small anisotropy is detected for the V 3d\nstates. The macroscopic properties of the V2GeC nanolaminate result from the\nchemical bonds with the anisotropic pattern as shown in this work."
    },
    {
        "anchor": "Thermodynamics of strongly frustrated magnet in a field: Ising\n  antiferromagnet on triangular Husimi lattice: Some strongly frustrated magnets such as the \"spin-ice\" compounds fail to\nproduce any magnetic order at finite temperatures even in the presence of\nmagnetic field. Still they have very unusual low-temperature thermodynamic\nproperties related to the field-induced ground state transitions. Here we show\nthat general qualitative picture of such peculiar thermodynamics can be\nobtained in the antiferromagnetic Ising model on the triangular Husimi lattice.\nThe analytical results for this model show magnetic plateaus, entropy spikes,\ncrossing points and peculiarities in magnetic susceptibility and specific heat\nbehavior reflecting the existence of ground state transitions. These signatures\nof strong frustration may help in search of new frustrated magnets and in the\ninterpretation of experimental data.",
        "positive": "Uniaxial pressure induced half-metallic ferromagnetic phase transition\n  in LaMnO$_3$: We use first-principles theory to predict that the application of uniaxial\ncompressive strain leads to a transition from an antiferromagnetic insulator to\na ferromagnetic half-metal phase in LaMnO$_3$. We identify the Q2 Jahn-Teller\nmode as the primary mechanism that drives the transition, indicating that this\nmode can be used to tune the lattice, charge, and spin coupling. Applying\n$\\simeq$ 6 GPa of uniaxial pressure along the [010] direction activates the\ntransition to a half-metallic $\\textit{pseudo-cubic}$ state. The\nhalf-metallicity opens the possibility of producing colossal magnetoresistance\nin the stoichiometric LaMnO$_3$ compound at significantly lower pressure\ncompared to recently observed investigations using hydrostatic pressure."
    },
    {
        "anchor": "Role of microenvironment in the mixed Langmuir-Blodgett films: This paper reports the pi-A isotherms and spectroscopic characteristics of\nmixed Langmuir and Langmuir-Blodgett (LB) films of non-amphiphilic carbazole\n(CA) molecules mixed with polymethyl methacrylate (PMMA) and stearic acid (SA).\npi-A isotherm studies of mixed monolayer and as well as also the collapse\npressure study of isotherms definitely conclude that CA is incorporated into\nPMMA and SA matrices. However CA is stacked in the PMMA/SA chains and forms\nmicrocrystalline aggregates as is evidenced from the scanning electron\nmicrograph picture. Nature of these aggregated species in the mixed LB films\nhas been revealed by UV-Vis absorption and fluorescence spectroscopic studies.\nThe presence of two different kinds of band systems in the fluorescence spectra\nof the mixed LB films have been observed. This may be due to the formation of\nlow dimensional aggregates in the mixed LB films. Intensity distribution of\ndifferent band system is highly sensitive to the microenvironment of two\ndifferent matrices as well as also on the film thickness",
        "positive": "Two-dimensional non-linear hydrodynamics and nanofluidics: A water monolayer squeezed between two solid planes experiences strong\nout-of-plane confinement effects while expanding freely within the plane. As a\nconsequence, the transport of such two-dimensional water combines hydrodynamic\nand nanofluidic features, intimately linked with each other. In this paper, we\npropose and explicitly solve a non-linear hydrodynamic equation describing\ntwo-dimensional water flow with viscosity parameters deduced from molecular\ndynamic simulations. We demonstrate that the very ability of two-dimensional\nwater to flow in short channels is governed by the second (dilatational)\nviscosity coefficient, leading to flow compression and velocity saturation in\nthe high-pressure limit. The viscosity parameter values depend strongly on\nwhether graphene or hexoganal boron nitride layers are used to confine 2D water\nthat offers an interesting opportunity to obtain various nanofluids out of the\nsame water molecules just by using alternate materials to fabricate the 2D\nchannels."
    },
    {
        "anchor": "Role of local structural distortions on the origin of j=1/2 pseudo-spin\n  state in sodium iridate: Na2IrO3 (NIO) is known to be a spin-orbit (SO) driven j=1/2 pseudo-spin\nMott-Hubbard (M-H) insulator. However, the microscopic origin of the\npseudo-spin state and the role of local structural distortions have not been\nclearly understood. Using a combination of theoretical calculations and x-ray\nspectroscopy, we show that the energetics in the vicinity of Fermi level (EF)\nis governed by SO interactions, electron correlation and local octahedral\ndistortions. Contrary to the earlier understanding, here we show that the j=3/2\nand 1/2 pseudo-spin states have admixture of both t2g and eg characters due to\nlocal structural distortion. Reduction of local octahedral symmetry also\nenables Ir 5d- O2p hybridization around the EF resulting in a M-H insulator\nwith enhanced charge transfer character. The possibility of Slater insulator\nphase is also ruled out by a combination of absence of room temperature DoS in\nvalence band spectra, calculated moments and temperature dependent\nmagnetization measurements.",
        "positive": "Recovering 0 Kelvin Effective Hamiltonian Parameters from\n  High-Temperature Disordered Phases: Effective Hamiltonians, when used in tandem with statistical mechanics\ntechniques, offer a rigorous connection between 0 Kelvin ab-initio predictions\nand finite temperature experimental observations. For alloys, cluster expansion\nHamiltonians can coarse-grain out the complex, many-body electron problem of\ndensity functional theory, yielding a series of simple site-wise basis\nfunctions (e.g., products of site occupancy variables) on an atomic scale. The\nresulting energy polynomial is computationally inexpensive, and hence suitable\nfor the (tens of) thousands of calculations of large systems required by\nstochastic methods. We present a new method to run the statical mechanics\nproblem \"in reverse\", using high-temperature observations and thermodynamic\nconnections to construct an effective Hamiltonian and thereby predict the 0\nKelvin energy spectrum and associated ground states. By re-examining the\ncluster expansion formalism through the lens of entropy-maximization\napproaches, we develop an algorithm to select clusters and determine cluster\ninteractions using only a few, high-temperature experiments on disordered\nphases. We demonstrate that our approach can recover not only the stable ground\nstates at 0 Kelvin, but also the full phase behavior for three realistic\ntwo-dimensional and three-dimensional alloy test-cases."
    },
    {
        "anchor": "Electron Localization Enhances Cation Diffusion in Transition Metal\n  Oxides: An Electronic Trebuchet Effect: Ion diffusion is a central part of materials physics of fabrication,\ndeformation, phase transformation, structure stability and electrochemical\ndevices. Conventional theory focuses on the defects that mediate diffusion and\nexplains how their populations influenced by oxidation, reduction, irradiation\nand doping can enhance diffusion. However, we have found the same influences\ncan also elevate their mobility by orders of magnitude in several prototypical\ntransition-metal oxides. First-principles calculation fundamentally connects\nthe latter observation to migrating ion's local structure, which is inherently\nsoft and has a broken symmetry, making it susceptible to electron or hole\nlocalization, thereby realizing a lower saddle-point energy. This finding\nresolves an unanswered question in physical ceramics of the past 30 years: why\ncation diffusion against the prediction of classical nonstoichiometric defect\nphysics is enhanced in reduced zirconia, ceria and structurally related\nceramics? It also suggests the saddle-point electron-phonon interaction that\nenables a negative-U state is akin to the counterweight effect that enables a\ntrebuchet. This simple picture for the transitional state explains why enhanced\nkinetics mediated by radical-like-ion migration occurs often, especially under\nextreme conditions.",
        "positive": "All-electron GW approximation with the mixed basis expansion based on\n  the full-potential LMTO method: We present a new all-electron, augmented-wave implementation of the GW\napproximation using eigenfunctions generated by a recent variant of the\nfull-potential LMTO method. The dynamically screened Coulomb interaction W is\nexpanded in a mixed basis set which consists of two contributions, local\natom-centered functions confined to muffin-tin spheres, and plane waves with\nthe overlap to the local functions projected out. The former can include any of\nthe core states; thus the core and valence states can be treated on an equal\nfooting. Systematic studies of semiconductors and insulators show that the GW\nfundamental bandgaps consistently fall low in comparison to experiment, and\nalso the quasiparticle levels differ significantly from other, approximate\nmethods, in particular those that approximate the core with a pseudopotential."
    },
    {
        "anchor": "Machine-learned Interatomic Potentials for Alloys and Alloy Phase\n  Diagrams: We introduce machine-learned potentials for Ag-Pd to describe the energy of\nalloy configurations over a wide range of compositions. We compare two\ndifferent approaches. Moment tensor potentials (MTP) are polynomial-like\nfunctions of interatomic distances and angles. The Gaussian Approximation\nPotential (GAP) framework uses kernel regression, and we use the Smooth Overlap\nof Atomic Positions (SOAP) representation of atomic neighbourhoods that\nconsists of a complete set of rotational and permutational invariants provided\nby the power spectrum of the spherical Fourier transform of the neighbour\ndensity. Both types of potentials give excellent accuracy for a wide range of\ncompositions and rival the accuracy of cluster expansion, a benchmark for this\nsystem. While both models are able to describe small deformations away from the\nlattice positions, SOAP-GAP excels at transferability as shown by sensible\ntransformation paths between configurations, and MTP allows, due to its lower\ncomputational cost, the calculation of compositional phase diagrams. Given the\nfact that both methods perform as well as cluster expansion would but yield\noff-lattice models, we expect them to open new avenues in computational\nmaterials modeling for alloys.",
        "positive": "The anisotropic grain size effect on the mechanical response of\n  polycrystals: The role of columnar grain morphology in additively\n  manufactured metals: Additively manufactured (AM) metals exhibit highly complex microstructures,\nparticularly with respect to grain morphology which typically features\nheterogeneous grain size distribution, anomalous and anisotropic grain shapes,\nand the so-called columnar grains. In general, the conventional morphological\ndescriptors are not suitable to represent complex and anisotropic grain\nmorphology of AM microstructures. The principal aspect of microstructural grain\nmorphology is the state of grain boundary spacing or grain size whose effect on\nthe mechanical response is known to be crucial. In this paper, we formally\nintroduce the notions of axial grain size and grain size anisotropy as robust\nmorphological descriptors which can concisely represent highly complex grain\nmorphologies. We instantiated a discrete sample of polycrystalline aggregate as\na representative volume element (RVE) which has random crystallographic\norientation and misorientation distributions. However, the instantiated RVE\nincorporates the typical morphological features of AM microstructures including\ndistinctive grain size heterogeneity and anisotropic grain size owing to its\npronounced columnar grain morphology. We ensured that any anisotropy arising in\nthe macroscopic mechanical response of the instantiated sample is mainly\nassociated with its underlying anisotropic grain size. The RVE was then used\nfor meso-scale full-field crystal plasticity simulations corresponding to\nuniaxial tensile deformation along different axes via a spectral solver and a\nphysics-based crystal plasticity constitutive model. Through the numerical\nanalyses, we were able to isolate the contribution of anisotropic grain size to\nthe anisotropy in the mechanical response of polycrystalline aggregates,\nparticularly those with the characteristic complex grain morphology of AM\nmetals. Such a contribution can be described by an inverse square relation."
    },
    {
        "anchor": "Bending crystals: Emergence of fractal dislocation structures: We provide a minimal continuum model for mesoscale plasticity, explaining the\ncellular dislocation structures observed in deformed crystals. Our dislocation\ndensity tensor evolves from random, smooth initial conditions to form\nself-similar structures strikingly similar to those seen experimentally -\nreproducing both the fractal morphologies and some features of the scaling of\ncell sizes and misorientations analyzed experimentally. Our model provides a\nframework for understanding emergent dislocation structures on the mesoscale, a\nbridge across a computationally demanding mesoscale gap in the multiscale\nmodeling program, and a new example of self-similar structure formation in\nnon-equilibrium systems.",
        "positive": "A scale up study on chemical segregation and the effects on tensile\n  properties in two medium Mn steel castings: Two ingots weighing 400 g and 5 kg with nominal compositions of\nFe-8Mn-4Al-2Si-0.5C-0.07V-0.05Sn were produced to investigate the effect of\nprocessing variables on microstructure development. The larger casting has a\ncooling rate more representative of commercial production and provides an\nunderstanding of the potential challenges arising from casting-related\nsegregation during efforts to scale up medium Mn steels, whilst the smaller\ncasting has a high cooling rate and different segregation pattern. Sections\nfrom both ingots were homogenised at 1250 \\degree C for various times to study\nthe degree of chemical homogeneity and $\\delta$-ferrite dissolution. Within 2\nh, the Mn segregation range (max $-$ min) decreased from 8.0 to 1.7 wt\\% in the\n400 g ingot and from 6.2 to 1.5 wt\\% in the 5 kg ingot. Some $\\delta$-ferrite\nalso remained untransformed after 2 h in both ingots but with the 5 kg ingot\nshowing nearly three times more than the 400 g ingot. Micress modelling was\ncarried out and good agreement was seen between predicted and measured\nsegregation levels and distribution. After thermomechanical processing, it was\nfound that the coarse untransformed $\\delta$-ferrite in the 5 kg ingot turned\ninto coarse $\\delta$-ferrite stringers in the finished product, resulting in a\nslight decrease in yield strength. Nevertheless, rolled strips from both ingots\nshowed $>$900 MPa yield strength, $>$1100 MPa tensile strength and $>$40\\%\nelongation with $<$10\\% difference in strength and no change in ductility when\ncompared to a fully homogenised sample."
    },
    {
        "anchor": "Magnetocaloric properties and critical behavior of\n  Co$_2$Cr$_{1-x}$Mn$_x$Al Heusler alloys: We study the magnetocaloric effect and critical behavior of\nCo$_2$Cr$_{1-x}$Mn$_x$Al ($x=$ 0.25, 0.5, 0.75) Heusler alloys across the\nferromagnetic (FM) transition (T$_{\\rm C}$). The Rietveld refinement of x-ray\ndiffraction patterns exhibit single phase cubic structure for all the samples.\nThe temperature dependent magnetic susceptibility $\\chi$(T) data show a\nsystematic enhancement in the Curie temperature and effective magnetic moment\nwith Mn concentration, which is consistent with the Slater-Pauling behavior.\nThe M(H) isotherms also exhibit the FM ordering and the analysis of $\\chi$(T)\ndata indicates the nature of the phase transition to be a second order, which\nis further supported by scaling of the entropy curves and Arrott plot.\nInterestingly, the Mn substitution causes an increase in the magnetic entropy\nchange and hence large relative cooling power for multi-stage magnetic\nrefrigerator applications. In order to understand the nature of the magnetic\nphase transition we examine the critical exponents $\\beta$, $\\gamma$, $\\delta$\nfor the $x=$ 0.75 sample by the modified Arrott plot and the critical isotherm\nanalysis, which is further confirmed by Kouvel-Fisher method and Widom scaling\nrelation, respectively. The estimated values of $\\beta=$ 0.507, $\\gamma=$\n1.056, $\\delta=$ 3.084 are found to be close to the mean field theoretical\nvalues. The renormalized isotherms (m vs h) corresponding to these exponent\nvalues collapse into two branches, above and below T$_{\\rm C}$ that validates\nour analysis. Our results suggest for the existence of long-range FM\ninteractions, which decays slower than power law as $J(r)\\sim r^{-4.5}$ for a 3\ndimensional mean field theory.",
        "positive": "Magnetic Properties Of Ni-Mo Single Crystal Alloys: Theory and\n  Experiment: The magnetization of Ni_{1-x}Mo_{x} single crystals with x=4,6,8 and 10 % by\nweight have been measured at 4.2K using a vibrating sample magnetometer and a\nSuperconducting Quantum Interference Device (SQUID). The magnetization of the\nalloy at these low concentrations and at 0 K have been theoretically determined\nby using the tight-binding linearized muffin-tin orbital method coupled with\naugmented space recursion. The theoretical data are compared with the\nexperiment."
    },
    {
        "anchor": "Density-Functional Theory and Tight-Binding Studies of the Geometry of\n  Hydrogen Adsorbed on Graphynes: Using density-functional theory and a tight-binding approach we investigate\nthe physical origin of distinct favourable geometries of adsorbed hydrogen\natoms in various graphyne structures, and the relation with electronic\nproperties. In particular, H atoms are adsorbed in-plane for $\\alpha$-graphyne,\nand they assume an oblique configuration in all other graphynes, including\n6,6,12-graphyne. The origin of different configurations is identified by means\nof a simple tight-binding model and it is controlled by the tuning of the\nhopping between sp$^2$-bonded C atoms and sp-bonded C atoms hybridized with the\nH atoms. We discuss in details how the geometry change of the attached H atom\ntunes the electronic properties like energy gap.",
        "positive": "Slip intermittency and dwell fatigue in titanium alloys: a discrete\n  dislocation plasticity analysis: Slip intermittency and stress oscillations in titanium alloy Ti-7Al-O that\nwere observed using in-situ far-field high energy X-ray diffraction microscopy\n(ff-HEDM) are investigated using a discrete dislocation plasticity (DDP) model.\nThe mechanistic foundation of slip intermittency and stress oscillations are\nshown to be dislocation escape from obstacles during stress holds, governed by\na thermal activation constitutive law. The stress drop events due to <a>-basal\nslip are larger in magnitude than those along <a>-prism, which is a consequence\nof their differing rate sensitivities, previously found from micropillar\ntesting. It is suggested that interstitial oxygen suppresses stress\noscillations by inhibiting the thermal activation process. Understanding of\nthese mechanisms is of benefit to the design and safety assessment of jet\nengine titanium alloys subjected to dwell fatigue."
    },
    {
        "anchor": "Supramolecular Chemistry Based on 4-Acetylbiphenyl on Au(111): On a gold surface, supramolecules composed of 4-acetylbiphenyl molecules show\nstructural directionality, reproducibility and robustness to external\nperturbations. We investigate the assembly of those molecules on the Au(111)\nsurface and analyze how the observed supramolecular structures are the result\nof weak long-range dispersive forces stabilizing the 4-acetylbiphenyl molecules\ntogether. Metallic adatoms serve as stabilizing agents. Our analysis suggests\nnew ways of creating complex molecular nano-objects that can eventually be used\nas devices or as seeds for extended hierarchical structures.",
        "positive": "Effect of SW defect on structural and transport properties of silicene\n  nanoribbons: Using density functional theory and non-equilibrium Greens function\ntechnique, we performed theoretical investigations on the structural and\ntransport properties of zigzag silicene nanoribbons with Stone-Wales defect.\nThe calculated formation energy is significantly lower than that of graphene\nand silicene, which implies the high stability of such defect in SiNRs.\nNegative differential resistance can be observed within certain bias voltage\nrange in both perfect and SW defected SiNRs. In order to elucidate the\nmechanism the NDR behavior,the transmission spectra and molecular projected\nself-consistent Hamiltonian states are discussed in details."
    },
    {
        "anchor": "Kinetics of propagating phase transformation in compressed bismuth: We observed dynamically driven phase transitions in isentropically compressed\nbismuth. By changing the stress loading conditions we explored two distinct\ncases: one in which the experimental signature of the phase transformation\ncorresponds to phase-boundary crossings initiated at both sample interfaces,\nand another in which the experimental trace is due to a single advancing\ntransformation front in the bulk of the material. We introduce a coupled\nkinetics - hydrodynamics model that for this second case enables us, under\nsuitable simplifying assumptions, to directly extract characteristic transition\ntimes from the experimental measurements.",
        "positive": "Novel Self-passivation Rule and Structure of CdTe sigma3 (112) Grain\n  Boundary: The theoretical study of grain boundaries (GBs) in polycrystalline\nsemiconductors is currently stalemated by their complicated nature, which is\ndifficult to extract from any direct experimental characterization. Usually,\ncoincidence-site-lattice (CSL) models are constructed simply by aligning two\nsymmetric planes, ignoring various possible reconstructions. Here, we propose a\ngeneral self-passivation rule to determine the low-energy GB reconstruction,\nand find new configurations for the CdTe sigma3 (112) GBs. First-principles\ncalculations show that it has lower formation energies than the prototype GBs\nadopted widely in previous studies. Surprisingly, the reconstructed GBs show\nself-passivated electronic properties without deep-level states in the band\ngap. Based on the reconstructed configurations, we revisited the influence of\nCdCl2 post-treatment on the CdTe GBs, and found that the addition of both Cd\nand Cl atoms in the GB improves the photovoltaic properties by promoting\nself-passivation and inducing n-type levels, respectively. The present study\nprovides a new route for further studies of GBs in covalent polycrystalline\nsemiconductors and also highlights that previous studies on the GBs of\nmultinary semiconductors which are based on the unreconstructed prototype GB\nmodels, should be revisited."
    },
    {
        "anchor": "Monte Carlo investigation of the magnetic anisotropy in Fe/Dy\n  multilayers: By Monte Carlo simulations in the canonical ensemble, we have studied the\nmagnetic anisotropy in Fe/Dy amorphous multilayers. This work has been\nmotivated by experimental results which show a clear correlation between the\nmagnetic perpendicular anisotropy and the substrate temperature during\nelaboration of the samples. Our aim is to relate macroscopic magnetic\nproperties of the multilayers to their structure, more precisely their\nconcentration profile. Our model is based on concentration dependent exchange\ninteractions and spin values, on random magnetic anisotropy and on the\nexistence of locally ordered clusters that leads to a perpendicular\nmagnetisation. Our results evidence that a compensation point occurs in the\ncase of an abrupt concentration profile. Moreover, an increase of the\nnoncollinearity of the atomic moments has been evidenced when the Dy anisotropy\nconstant value grows. We have also shown the existence of inhomogeneous\nmagnetisation profiles along the samples which are related to the concentration\nprofiles.",
        "positive": "From Kohn-Sham to many-electron energies via step structures in the\n  exchange-correlation potential: Accurately describing excited states within Kohn-Sham (KS) density functional\ntheory (DFT), particularly those which induce ionization and charge transfer,\nremains a great challenge. Common exchange-correlation (xc) approximations are\nunreliable for excited states owing, in part, to the absence of a derivative\ndiscontinuity in the xc energy ($\\Delta$), which relates a many-electron energy\ndifference to the corresponding KS energy difference. We demonstrate,\nanalytically and numerically, how the relationship between KS and many-electron\nenergies leads to the step structures observed in the exact xc potential, in\nfour scenarios: electron addition, molecular dissociation, excitation of a\nfinite system, and charge transfer. We further show that steps in the potential\ncan be obtained also with common xc approximations, as simple as the LDA, when\naddressed from the ensemble perspective. The article therefore highlights how\ncapturing the relationship between KS and many-electron energies with advanced\nxc approximations is crucial for accurately calculating excitations, as well as\nthe ground-state density and energy of systems which consist of distinct\nsubsystems."
    },
    {
        "anchor": "Equation of motion and subsonic-transonic transitions of rectilinear\n  edge dislocations: A collective-variable approach: A theoretical framework is proposed to derive a dynamic equation motion for\nrectilinear dislocations within isotropic continuum elastodynamics. The theory\nrelies on a recent dynamic extension of the Peierls-Nabarro equation, so as to\naccount for core-width generalized stacking-fault energy effects. The degrees\nof freedom of the solution of the latter equation are reduced by means of the\ncollective-variable method, well known in soliton theory, which we reformulate\nin a way suitable to the problem at hand. Through these means, two coupled\ngoverning equations for the dislocation position and core width are obtained,\nwhich are combined into one single complex-valued equation of motion, of\ncompact form. The latter equation embodies the history dependence of\ndislocation inertia. It is employed to investigate the motion of an edge\ndislocation under uniform time-dependent loading, with focus on the\nsubsonic/transonic transition. Except in the steady-state supersonic range of\nvelocities---which the equation does not address---our results are in good\nagreement with atomistic simulations on tungsten. In particular, we provide an\nexplanation for the transition, showing that it is governed by a\nloading-dependent dynamic critical stress. The transition has the character of\na delayed bifurcation. Moreover, various quantitative predictions are made,\nthat could be tested in atomistic simulations. Overall, this work demonstrates\nthe crucial role played by core-width variations in dynamic dislocation motion.",
        "positive": "Unique thickness-dependent properties of the van der Waals interlayer\n  antiferromagnet $\\mathrm{MnBi_2Te_4}$ films: Using density functional theory and Monte Carlo calculations, we study the\nthickness dependence of the magnetic and electronic properties of a van der\nWaals interlayer antiferromagnet in the two-dimensional limit. Considering\n$\\mathrm{MnBi_2Te_4}$ as a model material, we find it to demonstrate a\nremarkable set of thickness-dependent magnetic and topological transitions.\nWhile a single septuple layer block of $\\mathrm{MnBi_2Te_4}$ is a topologically\ntrivial ferromagnet, the thicker films made of an odd (even) number of blocks\nare uncompensated (compensated) interlayer antiferromagnets, which show wide\nbandgap quantum anomalous Hall (zero plateau quantum anomalous Hall) states.\nThus, $\\mathrm{MnBi_2Te_4}$ is the first stoichiometric material predicted to\nrealize the zero plateau quantum anomalous Hall state intrinsically. This state\nhas been theoretically shown to host the exotic axion insulator phase."
    },
    {
        "anchor": "On the flexoviscous behavior in viscoelastic materials: A phenomenological model on the relationship between viscoelasticity and\nflexoelectricity is proposed to address the electromechanical coupling under\nrheological processes in viscoelastic materials. Our theoretical studies show\nthat some observed ferroelectric phenomena in certain viscoelastic materials,\nlike polymer films, may not be intrinsic material behavior.",
        "positive": "A crystal symmetry-invariant Kobayashi--Warren--Carter grain boundary\n  model and its implementation using a thresholding algorithm: One of the most important aims of grain boundary modeling is to predict the\nevolution of a large collection of grains in phenomena such as abnormal grain\ngrowth, coupled grain boundary motion, and recrystallization that occur under\nextreme thermomechanical loads. A unified framework to study the coevolution of\ngrain boundaries with bulk plasticity has recently been developed by Admal et\nal. (2018), which is based on modeling grain boundaries as continuum\ndislocations governed by an energy based on the Kobayashi--Warren--Carter (KWC)\nmodel (Kobayashi et al., 1998, 2000). While the resulting unified model\ndemonstrates coupled grain boundary motion and polygonization (seen in\nrecrystallization), it is restricted to grain boundary energies of the\nRead--Shockley type, which applies only to small misorientation angles. In\naddition, the implementation of the unified model using finite elements\ninherits the computational challenges of the KWC model that originate from the\nsingular diffusive nature of its governing equations. The main goal of this\nstudy is to generalize the KWC functional to grain boundary energies beyond the\nRead--Shockley-type that respect the bicrystallography of grain boundaries. The\ncomputational challenges of the KWC model are addressed by developing a\nthresholding method that relies on a primal dual algorithm and the fast\nmarching method, resulting in an O(NlogN) algorithm, where N is the number of\ngrid points. We validate the model by demonstrating the Herring angle relation,\nfollowed by a study of the grain microstructure evolution in a two-dimensional\nface-centered cubic copper polycrystal with crystal symmetry-invariant grain\nboundary energy data obtained from the lattice matching method of Runnels et\nal. (2016a,b)."
    },
    {
        "anchor": "Softening the ultra-stiff: controlled variation of Young's modulus in\n  single crystal diamond: A combined experimental and numerical study on the variation of the elastic\nproperties of defective single-crystal diamond is presented for the first time,\nby comparing nano-indentation measurements on MeV-ion-implanted samples with\nmulti-scale modeling consisting of both ab initio atomistic calculations and\nmeso-scale Finite Element Method (FEM) simulations. It is found that by locally\nintroducing defects in the 2x10^18 - 5x10^21 cm-3 density range, a significant\nreduction of, as well as of density, can be induced in the diamond crystal\nstructure without incurring in the graphitization of the material. Ab initio\natomistic simulations confirm the experimental findings with a good degree of\nconfidence. FEM simulations are further employed to verify the consistency of\nmeasured deformations with a stiffness reduction, and to derive strain and\nstress levels in the implanted region. Combining these experimental and\nnumerical results, we also provide insight into the mechanism responsible for\nthe depth dependence of the graphitization threshold in diamond. This work\nprospects the possibility of achieving accurate tunability of the mechanical\nproperties of single-crystal diamond through defect engineering, with\nsignificant technological applications, i.e. the fabrication and control of the\nresonant frequency of diamond-based micromechanical resonators.",
        "positive": "Continuous Wire Reinforcement for Jammed Granular Architecture: The mechanical behavior of continuous fiber reinforced granular columns is\nsimulated by means of a Discrete Element Model. Spherical particles are\nrandomly deposited simultaneously with a wire, that is deployed following\ndifferent patterns inside of a flexible cylinder for triaxial compression\ntesting. We quantify the effect of three different fiber deployment patterns on\nthe failure envelope, represented by Mohr-Coulomb cones, and derive suggestions\nfor improved deployment strategies."
    },
    {
        "anchor": "Robust Surface Doping of Bi$_2$Se$_3$ by Rb Intercalation: Rubidium adsorption on the surface of the topological insulator Bi$_2$Se$_3$\nis found to induce a strong downward band bending, leading to the appearance of\na quantum-confined two dimensional electron gas states (2DEGs) in the\nconduction band. The 2DEGs shows a strong Rashba-type spin-orbit splitting, and\nit has previously been pointed out that this has relevance to nano-scale\nspintronics devices. The adsorption of Rb atoms, on the other hand, renders the\nsurface very reactive and exposure to oxygen leads to a rapid degrading of the\n2DEGs. We show that intercalating the Rb atoms, presumably into the van der\nWaals gaps in the quintuple layer structure of Bi$_2$Se$_3$, drastically\nreduces the surface reactivity while not affecting the promising electronic\nstructure. The intercalation process is observed above room temperature and\naccelerated with increasing initial Rb coverage, an effect that is ascribed to\nthe Coulomb interaction between the charged Rb ions. Coulomb repulsion is also\nthought to be responsible for a uniform distribution of Rb on the surface.",
        "positive": "DFT study of La$_2$Ce$_2$O$_7$: disordered fluorite vs pyrochlore\n  structure: The crystal structure of Lanthanum Cerium Oxide (La$_2$Ce$_2$O$_7$) is\ninvestigated using \\textit{ab initio} density functional theory (DFT)\ncalculations. The relative stability of fluorite- and pyrochlore-like\nstructures is studied through comparison of their formation energies. These\nformation energies show the pyrochlore structure to be favored over the\nfluorite structure, apparently contradicting the conclusions based on\nexperimental neutron and X-ray diffraction (XRD). By calculating and comparing\nXRD spectra for a set of differently ordered and random structures, we show\nthat the pyrochlore structure is consistent with diffraction experiments. For\nthese reasons, we suggest the pyrochlore structure as the ground state crystal\nstructure for La$_2$Ce$_2$O$_7$. %we show that among the structures considered\nin this work, the pyrochlore geometry is clearly favorable over the disordered\nfluorite geometry."
    },
    {
        "anchor": "NMR shieldings from density functional perturbation theory: GIPAW versus\n  all-electron calculations: We present a benchmark of the density functional linear response calculation\nof NMR shieldings within the Gauge-Including Projector-Augmented-Wave method\nagainst all-electron Augmented-Plane-Wave$+$local-orbital and uncontracted\nGaussian basis set results for NMR shieldings in molecular and solid state\nsystems. In general, excellent agreement between the aforementioned methods is\nobtained. Scalar relativistic effects are shown to be quite large for nuclei in\nmolecules in the deshielded limit. The small component makes up a substantial\npart of the relativistic corrections.",
        "positive": "Magnetism tailored by mechanical strain engineering in PrVO$_3$ thin\n  films: Transition-metal oxides with an ABO$_3$ perovskite structure exhibit strongly\nentangled structural and electronic degrees of freedom and thus, one expects to\nunveil exotic phases and properties by acting on the lattice through various\nexternal stimuli. Using the Jahn-Teller active praseodymium vanadate\nPr$^{3+}$V$^{3+}$O$_3$ compound as a model system, we show that PrVO$_3$ N\\'eel\ntemperature T$_N$ can be raised by 40 K with respect to the bulk when grown as\nthin films. Using advanced experimental techniques, this enhancement is\nunambiguously ascribed to a tetragonality resulting from the epitaxial\ncompressive strain experienced by the films. First-principles simulations not\nonly confirm experimental results, but they also reveal that the strain\npromotes an unprecedented orbital-ordering of the V$^{3+}$ d electrons,\nstrongly favouring antiferromagnetic interactions. These results show that an\naccurate control of structural aspects is the key for unveiling unexpected\nphases in oxides."
    },
    {
        "anchor": "Ab initio study of the crystal and electronic structure of mono- and\n  bi-alkali antimonides: Stability, Goldschmidt-like tolerance factors, and\n  optical properties: Mono- and bi-alkali antimonides, X$_2$YSb (X and Y from Group I), are\npromising for next-generation electron emitters due to their capability of\nproducing high-quality electron beams. However, these materials are not yet\nwell understood, in part due to the technical challenges in growing pure,\nordered alkali antimonides. For example, in the current literature there is a\nlack of complete understanding of the mechanically stable crystal structures of\nthese materials. As a first step towards understanding this issue, this paper\npresents an ab initio study of stability of single-crystal mono- and bi-alkali\nantimonides in the $D0_3$ structure, the structure generally assumed in the\nliterature for these materials. Finding that many of these materials actually\nare unstable in the $D0_3$ structure, we formulate a new set of\nGoldschmidt-like tolerance factors that accurately predict $D0_3$ stability\nusing a procedure analogous to machine-learning perceptron-based analysis.\nNext, we consider possible stable structures for materials that we predict to\nbe unstable in the $D0_3$ structure. Taking as examples the mono- and bi-alkali\nantimonides Cs$_3$Sb and Cs$_2$KSb, which also are technologically interesting\nfor photoemission and photoabsorption applications, respectively, we note that\nthe most unstable phonon displacements are consistent with the cubic structure,\nand we therefore perform extensive ab initio searches to identify potential\nground-state structures in a cubic lattice. Our X-ray diffraction experiments\nconfirm that indeed these two materials are not stable in the $D0_3$ structure\nand show scattering that is consistent with our new, proposed stable\nstructures. Finally, we explore ab initio the implications of the breaking of\nthe $D0_3$ symmetry on the electronic structure, showing significant impact on\nthe location of the optical absorption edge.",
        "positive": "Atomic step disorder on polycrystalline surfaces leads to spatially\n  inhomogeneous work functions: Structural disorder causes materials surface electronic properties, e.g. work\nfunction ($\\phi$) to vary spatially, yet it is challenging to prove exact\ncausal relationships to underlying ensemble disorder, e.g. roughness or\ngranularity. For polycrystalline Pt, nanoscale resolution photoemission\nthreshold mapping reveals a spatially varying $\\phi= 5.70\\pm 0.03$~eV over a\ndistribution of (111) textured vicinal grain surfaces prepared by sputter\ndeposition and annealing. With regard to field emission and related phenomena,\ne.g. vacuum arc initiation, a salient feature of the $\\phi$ distribution is\nthat it is skewed with a long tail to values down to 5.4 eV, i.e. far below the\nmean, which is exponentially impactful to field emission via the\nFowler-Nordheim relation. We show that the $\\phi$ spatial variation and\ndistribution can be explained by ensemble variations of granular tilts and\nsurface slopes via a Smoluchowski smoothing model wherein local $\\phi$\nvariations result from spatially varying densities of electric dipole moments,\nintrinsic to atomic steps, that locally modify $\\phi$. Atomic step-terrace\nstructure is confirmed with scanning tunneling microscopy (STM) at several\nlocations on our surfaces, and prior works showed STM evidence for atomic step\ndipoles at various metal surfaces. From our model, we find an atomic step edge\ndipole $\\mu=0.12$ D/edge atom, which is comparable to values reported in\nstudies that utilized other methods and materials. Our results elucidate a\nconnection between macroscopic $\\phi$ and nanostructure that may contribute to\nthe spread of reported $\\phi$ for Pt and other surfaces, and may be useful\ntoward more complete descriptions of polycrystalline metals in models of field\nemission and other related vacuum electronics phenomena, e.g. arc initiation."
    },
    {
        "anchor": "Quantum equations for vibrational dynamics on metal surfaces: A first-principles treatment of the vibrational dynamics of molecular\nchemisorbates on metal surfaces is presented. It is shown that the mean field\nquantum evolution of the vibrational position operator is determined by a\nquantum Langevin equation with an electronic friction. In the mean field limit,\nthe quantum noise and friction are related by the quantum\nfluctuation-dissipation theorem. The classical limit of this model is shown to\nagree with previously proposed models. A criterion is presented to describe the\nvalidity of the weak-coupling approximation and equations of motion for the\ndynamics in the presence of strong nonadiabatic coupling to electron-hole pairs\nare presented.",
        "positive": "Observation of transition from semiconducting to metallic ground state\n  in high-quality single crystalline FeSi: We report anomalous physical properties of single-crystalline FeSi over a\nwide temperature range 1.8-400 K. X-ray diffraction, specific heat, and\nmagnetization measurements indicate that the FeSi crystals synthesized in this\nstudy are of high quality with a very low concentration of magnetic impurities\n($\\sim$0.01$\\%$). The electrical resistivity $\\rho$($T$) can be described by\nactivated behavior with an energy gap $\\Delta$ = 57 meV between 67 K and 150 K.\nAt temperatures below 67 K, $\\rho$($T$) is significantly lower than an\nextrapolation of the activated behavior, and the Hall coefficient and\nmagneto-resistivity undergo a sign change in this region. At $\\sim$19 K, a\ntransition from semiconducting to metallic-like behavior is observed with\ndeceasing temperature. Whereas the transition temperature is very robust in a\nmagnetic field, the magnitude of the resistivity below $\\sim$30 K is very\nsensitive to magnetic field. There is no indication of a bulk phase transition\nor onset of magnetic order in the vicinity of either 67 K or 19 K from specific\nheat and magnetic susceptibility measurements. These measurements provide\nevidence for a conducting surface state in FeSi at low temperatures."
    },
    {
        "anchor": "Instrumentation for Millimeter-wave Magnetoelectrodynamic Investigations\n  of Low-Dimensional Conductors and Superconductors: We describe instrumentation for conducting high sensitivity millimeter-wave\ncavity perturbation measurements over a broad frequency range (40-200 GHz) and\nin the presence of strong magnetic fields (up to 33 tesla). A Millimeter-wave\nVector Network Analyzer (MVNA) acts as a continuously tunable microwave source\nand phase sensitive detector (8-350 GHz), enabling simultaneous measurements of\nthe complex cavity parameters (resonance frequency and Q-value) at a rapid\nrepetition rate (approx. 10 kHz). We discuss the principal of operation of the\nMVNA and the construction of a probe for coupling the MVNA to various\ncylindrical resonator configurations which can easily be inserted into a high\nfield magnet cryostat. We also present several experimental results which\ndemonstrate the potential of the instrument for studies of low-dimensional\nconducting systems.",
        "positive": "First principles study of pentacene on Au(111): We investigate the atomic and electronic structure of a single layer of\npentacene on the Au(111) surface using density functional theory. To find the\ncandidate structures we strain match the pentacene crystal geometry with the\nAu(111) surface, in this way we find pentacene overlayer structures with a low\nstrain. We show that the geometries obtained with this approach has lower\nenergy than previous proposed surface geometries of pentacene on Au(111). We\nalso show that the geometry and workfunction of the obtained structures are in\nexcellent agreement with experimental data."
    },
    {
        "anchor": "The first- and second-order magneto-optical effects and intrinsically\n  anomalous transport in 2D van der Waals layered magnets CrXY (X = S, Se, Te;\n  Y = Cl, Br, I): Recently, the two-dimensional magnetic semiconductor CrSBr has attracted\nconsiderable attention due to its excellent air-stable property and high\nmagnetic critical temperature. Here, we systematically investigate the\nelectronic structure, magnetocrystalline anisotropy energy, first-order\nmagneto-optical effects (Kerr and Faraday effects) and second-order\nmagneto-optical effects (Schafer-Hubert and Voigt effects) as well as\nintrinsically anomalous transport properties (anomalous Hall, anomalous Nernst,\nand anomalous thermal Hall effects) of two-dimensional van der Waals layered\nmagnets CrXY (X = S, Se, Te; Y = Cl, Br, I) by using the first-principles\ncalculations. Our results show that monolayer and bilayer CrXY (X = S, Se) are\nnarrow band gap semiconductors, whereas monolayer and bilayer CrTeY are\nmulti-band metals. The magnetic ground states of bilayer CrXY and the easy\nmagnetization axis of monolayer and bilayer CrXY are confirmed by the\nmagnetocrystalline anisotropy energy calculations. Utilizing magnetic group\ntheory analysis, the first-order magneto-optical effects as well as anomalous\nHall, anomalous Nernst, and anomalous thermal Hall effects are identified to\nexist in ferromagnetic state with out-of-plane magnetization. The second-order\nmagneto-optical effects are not restricted by the above symmetry requirements,\nand therefore can arise in ferromagnetic and antiferromagnetic states with\nin-plane magnetization. The calculated results are compared with the available\ntheoretical and experimental data of other two-dimensional magnets and some\nconventional ferromagnets. The present work reveals that monolayer and bilayer\nCrXY with superior magneto-optical responses and anomalous transport properties\nprovide an excellent material platform for the promising applications of\nmagneto-optical devices, spintronics, and spin caloritronics.",
        "positive": "Characteristics of a Nickel Vanadium redox flow battery Based on COMSOL: The overpotential, dissociation rate, electrode potential distributions and\ncurrent density are suggested in this study to analyze the Nickel Vanadium\nRedox Flow Battery (NVRFB). Due to its large capacity and ecofriendly\nproperties, NVRFB may be a viable option in the present state of energy\nconstraint and environmental pollution. Due to their low cost and high energy\ndensity, nickel-based flow batteries have gained popularity. This study\ndemonstrates that the Ni2+/Ni+ and V5+/V4+ ions have a higher rate of\ndissociation at the membrane and a lower rate at the inlet, where the\nelectrolyte flow velocity is greater; Because the membrane undergoes more\noxidation-reduction reactions, the electrolyte flow rate is critical in the\nredox flow cell; Additionally, we see that when electrode thickness is reduced,\ncurrent density and electrode potential increase while overpotential decreases;\nthe model's equations are solved using the finite-element method in the COMSOL\nMultiphysics program. An electrolyte-electrode interface connection is used to\nsimulate the reaction. The dissociation rate indicates that the\noxidation-reduction process happens at a lower membrane potential. Improving\nthe electrolyte flow rate enhances battery performance. Compression of the\nelectrodes enhances conductivity and battery performance."
    },
    {
        "anchor": "Catalytic effect of the spinel ferrite nanocrystals on the growth of\n  carbon nanotubes: We prepared three ferrite nanocatalysts: (i) copper ferrite (CuFe2O4), (ii)\nferrite where cobalt was substituted by nickel (NixCo1-xFe2O4, with x= 0, 0.2,\n0.4, 0.6), and (iii) ferrite where nickel was substituted by zinc\n(ZnyNi1-yFe2O4 with y= 1, 0.7, 0.5, 0.3), by the sol-gel method. The X-ray\ndiffraction patterns show that the ferrite samples have been crystallized in\nthe cubic spinel structural phase. We obtained the grain size by FE-SEM images\nin the range of 10-70 nm, and their magnetic properties by VSM. Next, carbon\nnanotubes were grown on these nanocatalysts by the CCVD method. We show that\nthe catalytic effects of these nanocrystals on the carbon nanotube growth\ndepend on cation distributions in the octahedral and tetrahedral sites,\nstructural isotropy and catalytic power due to cations. Our study can have\napplications in finding a suitable candidate of doped ferrite nanocrystals as\ncatalysts for carbon nanotube growth. More interestingly, the yield of the\nfabrication of carbon nanotubes can be considered as an indirect tool to study\ncatalytic activity of ferrites.",
        "positive": "A Study of S doped ZnSb: We report on S-doping of ZnSb for S concentrations ranging from 0.02 at% to\n2.5 at%. There are no previous reports on S-doping. ZnSb is a thermoelectric\nmaterial with some advantages for the temperature range 400 K - 600 K. The\nsolid solubility of S in ZnSb was estimated to be lower than 0.1% from\nobservations of precipitates by scanning microscopy. Hall and Seebeck\nmeasurements were performed as a function of temperature from 6K to 623 K. The\ntemperature dependence of the electrical properties suggests that S introduces\nneutral scattering centers for holes in the p-type material. An increase in\nhole concentration by S is argued by defect reactions involving Zn vacancies."
    },
    {
        "anchor": "Neutron scattering study of PbMg$_{1/3}$Ta$_{2/3}$O$_3$ and\n  BaMg$_{1/3}$Ta$_{2/3}$O$_3$ complex perovskites: Neutron scattering investigations were carried out in\nPbMg$_{1/3}$Ta$_{2/3}$O$_3$ and BaMg$_{1/3}$Ta$_{2/3}$O$_3$ complex\nperovskites. The crystal structure of both compounds does not show any phase\ntransition in the temperature range 1.5 -- 730 K. Whereas the temperature\ndependence of the lattice parameter of BaMg$_{1/3}$Ta$_{2/3}$O$_3$ follows the\nclassical expectations, the lattice parameter of relaxor ferroelectric\nPbMg$_{1/3}$Ta$_{2/3}$O$_3$ exhibits anomalies. One of these anomalies is\nobserved in the same temperature range as the peak in the dielectric\nsusceptibility. We find that in PbMg$_{1/3}$Ta$_{2/3}$O$_3$, lead ions are\ndisplaced from the ideal positions in the perovskite structure at all\ntemperatures. Consequently short-range order is present. This induces strong\ndiffuse scattering with an anisotropic shape in wavevector space. The\ntemperature dependences of the diffuse neutron scattering intensity and of the\namplitude of the lead displacements are similar.",
        "positive": "Hydrogen-mediated CVD epitaxy of Graphene on SiC: growth mechanism and\n  atomic configuration: Despite the large literature focused on the growth of graphene (Gr) on\n6H-SiC(0001) by chemical vapour deposition (CVD), some important issues have\nnot been solved and full wafer scale epitaxy of Gr remains challenging,\nhampering applications in microelectronics. With this study we shed light on\nthe generic mechanism which produces the coexistence of two different types of\nGr domains, whose proportion can be carefully controlled by tuning the H2 flow\nrate. For the first time, we show that the growth of Gr using CVD under H2/Ar\nflow rate proceeds in two stages. Firstly, the nucleation of free-standing\nepitaxial graphene on hydrogen (H-Gr) occurs, then H-atoms eventually desorb\nfrom either step edges or defects. This gives rise, for H2 flow rate below a\ncritical value, to the formation of (6x6)Gr domains on 6H-SiC(0001). The front\nof H-desorption progresses proportionally to the reduction of H2. Using a\nrobust and generic X-ray photoelectron spectroscopy (XPS) analysis, we\nrealistically quantify the proportions of H-Gr and (6x6)Gr domains of a Gr film\nsynthetized in any experimental conditions. Scanning tunnelling microscopy\nsupports the XPS measurements. From these results we can deduce that the H-\nassisted CVD growth of Gr developed here is a unique method to grow fully\nfree-standing H-Gr on the contrary to the method consisting of H-intercalation\nbelow epitaxial Gr on buffer layer. These results are of crucial importance for\nfuture applications of Gr/SiC(0001) in nanoelectronics, providing the\ngroundwork for the use of Gr as an optimal template layer for Van der Waals\nhomo- and hetero-epitaxy."
    },
    {
        "anchor": "Coronene: A High-Voltage Anion De-insertion Cathode for Potassium-Ion\n  Battery: Potassium-ion batteries have been envisioned to herald the age of low-cost\nand high-performance energy storage systems. However, the sparsity of viable\ncomponents has dampened the progress of these energy devices. Thus, herein, we\nreport coronene, a high-voltage cathode material that manifests a high-voltage\nof $4.1 \\rm V$ enkindled by anion (de)insertion. This work not only illuminates\nthe broad class of polycyclic aromatic hydrocarbons as prospective cathode\nmaterials but also sets a new benchmark for the performance of future organic\ncathode materials.",
        "positive": "Generalized balanced power diagrams for 3D representations of\n  polycrystals: Characterizing the grain structure of polycrystalline material is an\nimportant task in material science. The present paper introduces the concept of\ngeneralized balanced power diagrams as a concise alternative to voxelated\nmappings. Here, each grain is represented by (measured approximations of) its\ncenter-of-mass position, its volume and, if available, by its second-order\nmoments (in the non-equiaxed case). Such parameters may be obtained from 3D\nx-ray diffraction. As the exact global optimum of our model results from the\nsolution of a suitable linear program it can be computed quite efficiently.\nBased on verified real-world measurements we show that from the few parameters\nper grain (3, respectively 6 in 2D and 4, respectively 10 in 3D) we obtain\nexcellent representations of both equiaxed and non-equiaxed structures. Hence\nour approach seems to capture the physical principles governing the forming of\nsuch polycrystals in the underlying process quite well."
    },
    {
        "anchor": "Nanoscale mapping of the full strain tensor, rotation and composition in\n  partially relaxed In$_x$Ga$_{1-x}$N layers by scanning X-ray diffraction\n  microscopy: Strain and composition play a fundamental role in semiconductor physics,\nsince they are means to tune the electronic and optical properties of a\nmaterial and hence develop new devices. Today it is still a challenge to\nmeasure strain in epitaxial systems in a non-destructive manner which becomes\nespecially important in strain-engineered devices that often are subjected to\nintense stress. In this work, we demonstrate a microscopic mapping of the full\ntensors of strain and lattice orientation by means of scanning X-ray\ndiffraction microscopy. We develope a formalism to extract all components of\nstrain and orientation from a set of scanning diffraction measurements and\napply the technique to a patterned In$_x$Ga$_{1-x}$N double layer to study\nstrain relaxation and indium incorporation phenomena. The contributions due to\nvarying indium content and threading dislocations are separated and analyzed.",
        "positive": "New DRIE-Patterned Electrets for Vibration Energy Harvesting: This paper is about a new manufacturing process aimed at developing stable\nSiO2/Si3N4 patterned electrets using a Deep Reactive Ion Etching (DRIE) step\nfor an application in electret-based Vibration Energy Harvesters (e-VEH). This\nprocess consists in forming continuous layers of SiO2/Si3N4 electrets in order\nto limit surface conduction phenomena and is a new way to see the problem of\nelectret patterning. Experimental results prove that patterned electrets\ncharged by a positive corona discharge show excellent stability with high\nsurface charge densities that may reach 5mC/m^2 on 1.1\\mu m-thick layers, even\nwith fine patterning and harsh temperature conditions (up to 250{\\deg}C). This\npaves the way to new e-VEH designs and manufacturing processes."
    },
    {
        "anchor": "Nanocomposite si-c-n coatings: Coatings of ternary nanocomposite Si-C-N ceramic coatings have shown newer\nand improved mechanical and functional properties over the coarser and\nmonolithic coatings. Properties like high hardness, wear resistance, oxidation\nresistance, tunable band gap and chemical inertness have been observed for\nSi-C-N which makes its potential for numerous applications. Although lot of\nresearch has taken place in Si-C-N coatings, proper understanding of the effect\nof different parameters on the coating properties are still not resolved. The\nchanges occurring in fraction of Si, C and N and the phases forming in the\ncoatings with variation in deposition conditions require investigations. This\nresearch paper gives a systematic study of the role of different deposition\nparameters like substrate temperature, pressure, power on the nucleation and\ngrowth, structure, microstructural bonding and mechanical properties of the\nfilm deposited by magnetron sputtering which adds significantly to the\nfundamental knowledge of nanocomposite Si-C-N coatings as well as its\napplications.",
        "positive": "Observation of Giant Spin Splitting and d-wave Spin Texture in Room\n  Temperature Altermagnet RuO2: Recently, a novel magnetic phase called altermagnetism has been proposed,\nushering in a third distinct magnetic phase beyond ferromagnetism and\nantiferromagnetism. It is expected that this groundbreaking phase exhibits\nunique physical properties such as C-paired spin-valley locking, anomalous Hall\neffect, nontrivial Berry phase, and giant magnetoresistance, etc. Among all the\npredicted candidates, several room temperature altermagnets are suggested to\nhost significant potential applications in the near future. Nevertheless,\ndirect evidence about the spin pattern of the room temperature altermagnet is\nstill unrevealed. Previous studies found that RuO2 is identified as the most\npromising candidate for room temperature d-wave altermagnetism, exhibiting a\nsubstantial spin splitting of up to 1.4 eV. In this study, utilizing\nangle-resolved photoemission spectroscopy (ARPES), we report experimental\nobservation of the spin splitting in RuO2. Furthermore, employing spin-ARPES,\nwe directly observed the d-wave spin pattern. Our results unequivocally show\nthat RuO2 is a perfect d-wave altermagnet with great potential for upcoming\nspintronic applications."
    },
    {
        "anchor": "Performance of the modified Becke-Johnson potential: Very recently, in the 2011 version of the Wien2K code, the long standing\nshortcome of the codes based on Density Functional Theory, namely, its\nimpossibility to account for the experimental band gap value of semiconductors,\nwas overcome. The novelty is the introduction of a new exchange and correlation\npotential, the modified Becke-Johnson potential (mBJLDA). In this paper, we\nreport our detailed analysis of this recent work. We calculated using this\ncode, the band structure of forty one semiconductors and found an important\nimprovement in the overall agreement with experiment as Tran and Blaha [{\\em\nPhys. Rev. Lett.} 102, 226401 (2009)] did before for a more reduced set of\nsemiconductors. We find, nevertheless, within this enhanced set, that the\ndeviation from the experimental gap value can reach even much more than 20%, in\nsome cases. Furthermore, since there is no exchange and correlation energy term\nfrom which the mBJLDA potential can be deduced, a direct optimization procedure\nto get the lattice parameter in a consistent way is not possible as in the\nusual theory. These authors suggest that a LDA or a GGA optimization procedure\nis used previous to a band structure calculation and the resulting lattice\nparameter introduced into the 2011 code. This choice is important since small\npercentage differences in the lattice parameter can give rise to quite higher\npercentage deviations from experiment in the predicted band gap value.",
        "positive": "On the Phase Transitions That Cannot Materialize: The succession of suggested mechanisms of solid-state phase transitions -\nSecond-order, Lambda, Martensitic, Displacive, Topological, Order-Disorder,\nSoft-mode, Incommensurate, Scaling and Quantum - are analyzed and explained why\nthey cannot be realized in nature. All of them assume a cooperative structural\nrearrangement as opposed to the only real one which is simply a variant of the\ncrystal growth. Like all kinds of crystal growth, a solid state phase\ntransition proceeds by molecule-by-molecule building building the crystal of a\ndifferent structure, while the surrounding original crystal is used as the\nbuilding material."
    },
    {
        "anchor": "Recent advances in MXenes: from fundamentals to applications: The family of MAX phases and their derivative MXenes are continuously growing\nin terms of both crystalline and composition varieties. In the last couple of\nyears, several breakthroughs have been achieved that boosted the synthesis of\nnovel MAX phases with ordered double transition metals and, consequently, the\nsynthesis of novel MXenes with a higher chemical diversity and structural\ncomplexity, rarely seen in other families of two-dimensional (2D) materials.\nConsidering the various elemental composition possibilities, surface functional\ntunability, various magnetic orders, and large spin$-$orbit coupling, MXenes\ncan truly be considered as multifunctional materials that can be used to\nrealize highly correlated phenomena. In addition, owing to their large surface\narea, hydrophilicity, adsorption ability, and high surface reactivity, MXenes\nhave attracted attention for many applications, e.g., catalysts, ion batteries,\ngas storage media, and sensors. Given the fast progress of MXene-based science\nand technology, it is timely to update our current knowledge on various\nproperties and possible applications. Since many theoretical predictions remain\nto be experimentally proven, here we mainly emphasize the physics and chemistry\nthat can be observed in MXenes and discuss how these properties can be tuned or\nused for different applications.",
        "positive": "Formation of rectifier with gold nanoclusters: Gold nanoclusters encapsulated with organic molecules are of great interest\nfor its possible applications in the fields of molecular electronics, catalysis\nand medical science. Here we demonstrate that monolayer and bilayer films of\nthiol-capped gold nanoclusters can exhibit diode-like properties provided\ncontrolled spatial asymmetry exist between two tunnel junctions used to connect\na thiol capped gold nanoclusters. Current-voltage characteristics of this\nrectifier were obtained from conducting probe atomic force microscopy\nmeasurements and also from conventional two probe resistance measurements.\nSystematic x-ray reflectivity and atomic force microscopy measurements were\ncarried out to characterize the spatial asymmetry introduced by a monolayer of\nfatty acid salt gadolinium stearate used to deposit thiol-capped gold\nnanocluster molecules on hydrophilic SiO2-Si(001) substrate by Langmuir\nBlodgett technique. This information was used to explain prominent\nrectification observed in these nano-structured films."
    },
    {
        "anchor": "The classical molecular dynamics simulation of graphene on Ru(0001)\n  using a fitted Tersoff interface potential: The accurate molecular dynamics simulation of weakly bound adhesive\ncomplexes, such as supported graphene, is challenging due to the lack of an\nadequate interface potential. Instead of the widely used Lennard-Jones\npotential for weak and long-range interactions we use a newly parameterized\nTersoff-potential for graphene/Ru(0001) system. The new interfacial force field\nprovides adequate moir$\\acute{e}$ superstructures in accordance with scanning\ntunnelling microscopy images and with DFT results. In particular, the\ncorrugation of $\\xi \\approx 1.0 \\pm 0.2$ $\\hbox{\\AA}$ is found which is\nsomewhat smaller than found by DFT approaches ($\\xi \\approx 1.2$ $\\hbox{\\AA}$)\nand is close to STM measurements ($\\xi \\approx 0.8 \\pm 0.3$ $\\hbox{\\AA}$).The\nnew potential could open the way towards large scale simulations of supported\ngraphene with adequate moir$\\acute{e}$ supercells in many fields of graphene\nresearch. Moreover, the new interface potential might provide a new strategy in\ngeneral for getting accurate interaction potentials for weakly bound adhesion\nin large scale systems in which atomic dynamics is inaccessible yet by accurate\nDFT calculations.",
        "positive": "On three-dimensional dilational elastic metamaterials: Dilational materials are stable three-dimensional isotropic auxetics with an\nultimate Poisson's ratio of -1. We design, evaluate, fabricate, and\ncharacterize crystalline metamaterials approaching this ideal. To reveal all\nmodes, we calculate the phonon band structures. On this basis, using cubic\nsymmetry, we can unambiguously retrieve all different non-zero elements of the\nrank-4 effective metamaterial elasticity tensor, from which all effective\nelastic metamaterial properties follow. While the elastic properties and the\nphase velocity remain anisotropic, the effective Poisson's ratio indeed becomes\nisotropic and approaches -1 in the limit of small internal connections. This\nfinding is also supported by independent static continuum-mechanics\ncalculations. In static experiments on macroscopic polymer structures\nfabricated by three-dimensional printing, we measure Poisson's ratios as low as\n-0.8 in good agreement with theory. Microscopic samples are also presented."
    },
    {
        "anchor": "Compositionally Graded SS316 to C300 Maraging Steel using Additive\n  Manufacturing: Joining of dissimilar metals is required for numerous applications in\nindustries such as chemical, energy and automotive. It is challenging due to\ndifferences in melting point, density, and thermal expansion of the metals\nbeing joined. Common welding techniques involve limiting melting and\nsolidification to a narrow area leading to high thermal stresses and\npotentially brittle intermetallic phases. Furthermore, the geometric complexity\nof these welded joints can be rather limited. Additive Manufacturing (AM)\npresents new techniques for joining of dissimilar metals. One of the emerging\nmethods is the building of functionally graded parts using Directed Energy\nDeposition (DED) to spatially vary composition. In this paper, a SS316L and\nC300 maraging steel couple were joined by DED and heat treated. 13 discrete\ncomposition layers were selected using metallurgical considerations, in order\nto ensure a smooth transition in properties and microstructure. The mechanical\nproperties of the as-built joints were found to be similar to the SS part and\nno intermetallic phases were found in the interface.",
        "positive": "Ground state and constrained domain walls in Gd/Fe multilayers: The magnetic ground state of antiferromagnetically coupled Gd/Fe multilayers\nand the evolution of in-plane domain walls is modelled with micromagnetics. The\ntwisted state is characterised by a rapid decrease of the interface angle with\nincreasing magnetic field. We found that for certain ratios M(Fe):M(Gd), the\ntwisted state is already present at low fields. However, the magnetic ground\nstate is not only determined by the ratio M(Fe):M(Gd) but also by the\nthicknesses of the layers, that is the total moments of the layer. The\ndependence of the magnetic ground state is explained by the amount of overlap\nof the domain walls at the interface. Thicker layers suppress the Fe aligned\nand the Gd aligned state in favour of the twisted state. Whereas ultrathin\nlayers exclude the twisted state, since wider domain walls can not form in\nthese ultrathin layers."
    },
    {
        "anchor": "Symmetry-mode-based classical and quantum mechanical formalism of\n  lattice dynamics: We present classical and quantum mechanical descriptions of lattice dynamics,\nfrom the atomic to the continuum scale, using atomic scale symmetry modes and\ntheir constraint equations. This approach is demonstrated for a one-dimensional\nchain and a two-dimensional square lattice with a monatomic basis. For the\nclassical description, we find that rigid modes, in addition to the\ndistortional modes found before, are necessary to describe the kinetic energy.\nThe long wavelength limit of the kinetic energy terms expressed in terms of\natomic scale modes is shown to be consistent with the continuum theory, and the\nleading order corrections are obtained. For the quantum mechanical description,\nwe find conjugate momenta for the atomic scale symmetry modes. In direct space,\ngraphical rules for their commutation relations are obtained. Commutation\nrelations in the reciprocal space are also calculated. As an example, phonon\nmodes are analyzed in terms of symmetry modes. We emphasize that the approach\nbased on atomic scale symmetry modes could be useful, for example, for the\ndescription of multiscale lattice dynamics and the dynamics near structural\nphase transition.",
        "positive": "Voltage dependent first-principles barriers to Li transport within\n  Li-ion battery Solid-Electrolyte-Interphases: Charging a Li-ion battery requires Li ion transport between the cathode and\nthe anode. This Li-ion transport is dependent upon (among other factors) the\nelectrostatic environment the ion encounters within the\nSolid-Electrolyte-Interphase (SEI), which separates the anode from the\nsurrounding electrolyte. Previous first principles work has illuminated the\nreaction barriers through likely atomistic SEI environments, but has had\ndifficulty accurately reflecting the larger electrostatic potential landscape\nthat an ion encounters moving through the SEI. In this work, we apply the\nrecently developed Quantum Continuum Approximation (QCA) technique to provide\nan equilibrium electronic potentiostat for first-principles interface\ncalculations. Using QCA, we calculate the potential barrier for Li-ion\ntransport through LiF, Li$_2$O, and Li$_2$CO$_3$ SEIs along with LiF-LiF, and\nLiF-Li$_2$O grain boundaries, all paired with Li metal anodes. We demonstrate\nthat the SEI potential barrier is dependent on the anode electrochemical\npotentials in each system. Furthermore, we find that the threshold potential at\nwhich the SEI potential barrier switches from encouraging Li ion transport\ntoward the anode versus discouraging transport toward the anode is highly\ndependent on the exact SEI chemistry. Finally, we use these techniques to\nestimate the change in the diffusion barrier for a Li ion moving in a LiF SEI\nas a function of anode potential."
    },
    {
        "anchor": "Atomic Conversion Reaction Mechanism of WO3 in Secondary Ion Batteries: Conversion reaction is one of the most important chemical processes in energy\nstorage such as lithium ion batteries. While it is generally assumed that the\nconversion reaction is initiated by ion intercalation into the electrode\nmaterial, solid evidence of intercalation and the subsequent transition\nmechanism to conversion remain elusive. Here, using well-defined WO3 single\ncrystalline thin films grown on Nb doped SrTiO3(001) as a model electrode, we\nelucidate the conversion reaction mechanisms during Li+, Na+ and Ca2+ insertion\ninto WO3 by in situ transmission electron microscopy studies. Intercalation\nreactions are explicitly revealed for all ion insertions. With corroboration\nfrom first principle molecular simulations, it is found that, beyond\nintercalation, ion-oxygen bonding destabilize the W framework, which gradually\ncollapses to pseudo-amorphous structure. In addition, we show the interfacial\ntensile strain imposed by the SrTiO3 substrate can preserve the structure of an\nultra-thin layer of WO3, offering a possible engineering solution to improve\nthe cyclability of electrode materials. This study provides a detailed\natomistic picture on the conversion-type electrodes in secondary ion batteries.",
        "positive": "Thermoelectric figure of merit of tau-type conductors of several donors: Dimensionless thermoelectric figure of merit $ZT$ is investigated for\ntwo-dimensional organic conductors $\\tau-(EDO-S,S-DMEDT-TTF)_2(AuI_2)_{1+y}$,\n$\\tau$-(EDT-S,S-DMEDT-TTF)_2(AuI_2)_{1+y}$ and\n$\\tau$-(P-S,S-DMEDT-TTF)_2(AuI_2)_{1+y}$ ($y \\le 0.875$), respectively. The\n$ZT$ values were estimated by measuring electrical resistivity, thermopower and\nthermal conductivity simultaneously. The largest $ZT$ is 2.7 $\\times$ 10$^{-2}$\nat 155 K for $\\tau-(EDT-S,S-DMEDT-TTF)_2(AuI_2)_{1+y}$, 1.5 $\\times$ 10$^{-2}$\nat 180 K for $\\tau-(EDO-S,S-DMEDT-TTF)_2(AuI_2)_{1+y}$ and 5.4 $\\times$\n10$^{-3}$ at 78 K for $\\tau-(P-S,S-DMEDT-TTF)_2(AuI_2)_{1+y}$, respectively.\nSubstitution of the donor molecules fixing the counter anion revealed\nEDT-S,S-DMEDT-TTF is the best of the three donors to obtain larger $ZT$."
    },
    {
        "anchor": "Temperature dependent conductivity, dielectric relaxation, electrical\n  modulus and impedance spectroscopy of Ni substituted\n  Na$_{3+2x}$Zr$_{2-x}$Ni$_{x}$Si$_2$PO$_{\\rm 12}$: We investigate the structural, dielectric relaxation, electric modulus and\nimpedance behavior of Ni-doped NASICON ceramic\nNa$_{3+2x}$Zr$_{2-x}$Ni$_{x}$Si$_2$PO$_{\\rm 12}$ ($x=$ 0.05--0.2) prepared\nusing the solid-state reaction method. The increase in dielectric constant with\ntemperature and decrease with frequency is explained on the basis of space\ncharge polarization using the two-layer model of Maxwell-Wagner relaxation. The\ndielectric loss peak at lower temperatures follows the Arrhenius-type behavior\nwith frequency having activation energy of 0.27$\\pm$0.01~eV of dipolar\nrelaxation, suggests similar type of defects are responsible for all the doped\nsamples. The real ($\\epsilon$ $^{'}$) and imaginary ($\\epsilon$ $^{''}$)\npermittivity variation with frequency shows the broad relaxation behavior\nindicates the non-Debye type of relaxation in the measured temperature range.\nThe permittivity values decrease with the amount of doping due to the increased\nnumber of charge carriers upon Ni doping at the Zr site. The grain\ncontributions are observed at higher frequencies, while grain-boundary\ncontributions occur at the lower side of frequencies. The imaginary part of the\nelectric modulus also shows two types of relaxation peaks for all the samples\nindicating similar activation energy at low temperatures and variable\nactivation energy at higher temperatures. The fitting of the imaginary modulus\nusing KWW function shows the non-Debye type of relaxation. We find that all\nmodulus curves merge with each other at low temperatures showing a similar type\nof relaxation, while curves at high temperatures show the dispersed behavior\nabove the peak frequency. The {\\it a.c.} conductivity data are fitted using the\ndouble power law confirming the grain and grain boundary contributions in total\nconductivity.",
        "positive": "Tuning the electronic properties of hydrogen passivated C3N nanoribbons\n  through van der Waals stacking: The two-dimensional (2D) C3N has emerged as a material with promising\napplications in high performance device owing to its intrinsic bandgap and\ntunable electronic properties. Although there are several reports about the\nbandgap tuning of C3N via stacking or forming nanoribbon, bandgap modulation of\nbilayer C3N nanoribbons (C3NNRs) with various edge structures is still far from\nwell understood. Here, based on extensive first-principles calculations, we\ndemonstrated the effective bandgap engineering of C3N by cutting it into\nhydrogen passivated C3NNRs and stacking them into bilayer heterostructures. It\nwas found that armchair (AC) C3NNRs with three types of edge structures are all\nsemiconductors, while only zigzag (ZZ) C3NNRs with edges composed of both C and\nN atoms (ZZ-CN/CN) are semiconductors. The bandgaps of all semiconducting\nC3NNRs are larger than that of C3N nanosheet. More interestingly, AC-C3NNRs\nwith CN/CN edges (AC-CN/CN) possess direct bandgap while ZZ-CN/CN have indirect\nbandgap. Compared with the monolayer C3NNR, the bandgaps of bilayer C3NNRs can\nbe greatly modulated via different stacking orders and edge structures, varying\nfrom 0.43 eV for ZZ-CN/CN with AB'-stacking to 0.04 eV for AC-CN/CN with\nAA-stacking. Particularly, transition from direct to indirect bandgap was\nobserved in the bilayer AC-CN/CN heterostructure with AA'-stacking, and the\nindirect-to-direct transition was found in the bilayer ZZ-CN/CN with\nAB-stacking. This work provides insights into the effective bandgap engineering\nof C3N and offers a new opportunity for its applications in nano-electronics\nand optoelectronic devices."
    },
    {
        "anchor": "Surface magnetism of strontium titanate: SrTiO3 plays a central role in oxide electronics. It is the substrate of\nchoice for functional oxide heterostructures based on perovskite-structure\nthin-film stacks, and its surface or interface with a polar oxide such as\nLaAlO3 can become a two-dimensional conductor because of electronic\nreconstruction or the presence of oxygen defects. Inconsistent reports of\nmagnetic order in SrTiO3 abound in the literature. Here we report a systematic\nexperimental study aimed at establishing how and when SrTiO3 can develop a\nmagnetic moment at room temperature. Polished 100, 110 or 111 crystal slices\nfrom four different suppliers are characterized before and after vacuum\nannealing at 750 {\\deg}C, both in single-crystal and powdered form. Impurity\ncontent is analysed at the surface and in the bulk. Besides the underlying\nintrinsic diamagnetism of SrTiO3, magnetic signals are of three types-a Curie\nlaw susceptibility due to dilute magnetic impurities at the ppm level, a\nhysteretic, temperature-dependent ferromagnetic impurity contribution, and a\npractically-anhysteretic, defect-related temperature-independent component that\nsaturates in about 200 mT. The latter component is intrinsic. It is often the\nlargest, reaching 10 Bohr magnetons per nm2 of surface area or more and\ndominating the magnetic response in low fields at room temperature. It is\nassociated with defects near the surface, and can be destroyed by treatment\nwith Tiron (C6H4Na2O8S2), an electron donor molecule that forms a strong\ncomplex with titanium at the surface. The origin of this unusual\nhigh-temperature ferromagnetic-like response is discussed.",
        "positive": "Mode-resolved reciprocal space mapping of electron-phonon interaction in\n  the Weyl semimetal candidate Td-WTe$_2$: The selective excitation of coherent phonons provides unique capabilities to\ncontrol fundamental properties of quantum materials on ultrafast time scales.\nFor instance, in the presence of strong electron-phonon coupling, the\nelectronic band structure can become substantially modulated. Recently, it was\npredicted that by this means even topologically protected states of matter can\nbe manipulated and, ultimately, be destroyed: For the layered transition metal\ndichalcogenide Td-WTe$_2$, pairs of Weyl points are expected to annihilate as\nan interlayer shear mode drives the crystalline structure towards a\ncentrosymmetric phase. By monitoring the changes in the electronic structure of\nTd-WTe$_2$ with femtosecond resolution, we provide here direct experimental\nevidence that the coherent excitation of the shear mode acts on the electronic\nstates near the Weyl points. Band structure data in comparison with our results\nimply, furthermore, the periodic reduction in the spin splitting of bands near\nthe Fermi energy, a distinct electronic signature of the non-centrosymmetric Td\nground state of WTe$_2$. The comparison with higher-frequency coherent phonon\nmodes finally proves the shear mode-selectivity of the observed changes in the\nelectronic structure. Our real-time observations reveal direct experimental\ninsights into electronic processes that are of vital importance for a coherent\nphonon-induced topological phase transition in Td-WTe$_2$."
    },
    {
        "anchor": "Synthesis and luminescence properties of electrodeposited ZnO Films: ZnO films have been grown on gold (111) by electrodeposition using two\ndifferent OH- sources, nitrate and peroxide, in order to obtain a comparative\nstudy between these films. The morphology, structural and optical\ncharacterization of the films were investigated depending on the solution used\n(nitrate and peroxide) and the applied potential. Scanning Electron Microscopy\npictures show different morphologies in each case. X-Ray Diffraction confirms\nthat the films are pure ZnO oriented along the (0002) direction. ZnO films have\nbeen studied by photoluminescence to identify the emission of defects in the\nvisible range. A consistent model that explains the emissions for the different\nelectrodeposited ZnO films is proposed. We have associated the green and yellow\nemissions to a transition from the donor OH- to the acceptor zinc vacancies\n(VZn-) and to interstitial oxygen (Oi0), respectively. The orange-red emission\nis probably due to transitions from the conducting band to Oi- and OZn 0\ndefects and the infrared emission to transition from these Oi -/2- and OZn 0/-\ndefects to the valence band.",
        "positive": "High Thermoelectric Figure of Merit by Resonant Dopant in Half-Heusler\n  Alloys: Half-Heusler alloys have been one of the benchmark high temperature\nthermoelectric materials owing to their thermal stability and promising figure\nof merit ZT. Simonson et al. early showed that small amounts of vanadium doped\nin Hf0.75Zr0.25NiSn enhanced the Seebeck coefficient and correlated the change\nwith the increased density of states near the Fermi level. We herein report a\nsystematic study on the role of vanadium (V), niobium (Nb), and tantalum (Ta)\nas prospective resonant dopants in enhancing the ZT of n-type half-Heusler\nalloys based on Hf0.6Zr0.4NiSn0.995Sb0.005. The V doping was found to increase\nthe Seebeck coefficient in the temperature range 300-1000 K, consistent with a\nresonant doping scheme. In contrast, Nb and Ta act as normal n-type dopants, as\nevident by the systematic decrease in electrical resistivity and Seebeck\ncoefficient. The combination of enhanced Seebeck coefficient due to the\npresence of V resonant states and the reduced thermal conductivity has led to a\nstate-of-the-art ZT of 1.3 near 850 K in n-type\n(Hf0.6Zr0.4)0.99V0.01NiSn0.995Sb0.005 alloys."
    },
    {
        "anchor": "Screening of electron-phonon coupling in graphene on Ir(111): The phonon dispersion of graphene on Ir(111) has been determined by means of\nangle-resolved inelastic electron scattering and density functional\ncalculations. Kohn anomalies of the highest optical-phonon branches are\nobserved at the $\\Gamma$ and K point of the surface Brillouin zone. At K the\nKohn anomaly is weaker than observed from pristine graphene and graphite. This\nobservation is rationalized in terms of a decrease of the electron-phonon\ncoupling due to screening of graphene electron correlations by the metal\nsubstrate.",
        "positive": "Large Seebeck effect in the electron-doped FeAs$_2$ driven by quasi one\n  dimensional pudding-mold type band: We investigate the thermoelectric propeties of the electron-doped FeAs$_2$\nboth experimentally and theoretically. Electrons are doped by partially\nsubstituting Se for As, which leads to a metallic behavior in the resistivity.\nA Seebeck coefficient of about $-$200 $\\mu$V/K is reached at 300 K for 1%\ndoping, and about $-$120 $\\mu$V/K even at 5% doping. The origin of this large\nSeebeck coefficient despite the metallic conductivity is analyzed from a band\nstructure point of view. The first-principles band calculation reveals the\npresence of a pudding-mold type band just above the band gap, somewhat similar\nto Na$_x$CoO$_2$, but with a quasi-one-dimensional nature. We calculate the\nSeebeck coefficient using a tightbinding model that correctly reproduces this\nband structure, and this gives results close to the experimental observations.\nThe origin of this peculiar band shape is also discussed."
    },
    {
        "anchor": "Ultra-broadband bright light emission from a one-dimensional inorganic\n  van der Waals material: One-dimensional (1D) van der Waals materials have emerged as an intriguing\nplayground to explore novel electronic and optical effects. We report on\ninorganic one-dimensional SbPS4 nanotubes bundles obtained via mechanical\nexfoliation from bulk crystals. The ability to mechanically exfoliate SbPS4\nnanobundles offers the possibility of applying modern 2D material fabrication\ntechniques to create mixed-dimensional van der Waals heterostructures. We find\nthat SbPS4 can readily be exfoliated to yield long (> 10 {\\mu}m) nanobundles\nwith thicknesses that range from of 1.3 - 200 nm. We investigated the optical\nresponse of semiconducting SbPS4 nanobundles and discovered that upon\nexcitation with blue light, they emit bright and ultra-broadband red light with\na quantum yield similar to that of hBN-encapsulated MoSe2. We discovered that\nthe ultra-broadband red light emission is a result of a large ~1 eV exciton\nbinding energy and a ~200 meV exciton self-trapping energy, unprecedented in\nprevious material studies. Due to the bright and ultra-broadband light\nemission, we believe that this class of inorganic 1D van der Waals\nsemiconductors has numerous potential applications including on-chip tunable\nnanolasers, and applications that require ultra-violet to visible light\nconversion such as lighting and sensing. Overall, our findings open avenues for\nharnessing the unique characteristics of these nanomaterials, advancing both\nfundamental research and practical optoelectronic applications.",
        "positive": "Probing atomic environments in alloys by electron spectroscopy: In alloys exhibiting substitutional disorder, the variety of atomic\nenvironments manifests itself as a `disorder broadening' in their core level\nbinding energy spectra. Disorder broadening can be measured experimentally, and\nin principle can be used to deduce information about specific atomic\nenvironments within a sample. However, progress in this endeavor is hampered by\nthe lack of a model for this phenomenon which can treat complex systems. In\nthis work we describe such a model. The model is used to elucidate the\nrelationship between charge transfer, atomic environment, and disorder\nbroadening in complex systems, with a focus on the problem of characterizing\nthe interface quality of CuNi multilayers. We also validate the model against\nthe results of ab initio electronic structure calculations. Several\ncounterintuitive aspects of the disorder broadening phenomenon are uncovered,\nan understanding of which is essential for the correct interpretation of\nexperimental results. For instance, it is shown that systems with inhomogeneous\nconcentration profiles can exhibit disorder broadenings significantly larger\nthan random alloys. Furthermore in some systems a `disorder narrowing' is even\npossible."
    },
    {
        "anchor": "Graded anharmonic crystals as genuine thermal diodes: Analytical\n  description of rectification and negative differential thermal resistance: We address the heat flow study starting from microscopic models of matter: we\ndevelop an approach and investigate some anharmonic graded mass crystals, with\nweak interparticle interactions. We calculate the thermal conductivity, and\nshow the existence of rectification and negative differential thermal\nresistance. Our formalism allows us to understand the mechanism behind the\nphenomena, and shows that the properties of graded materials make them genuine\nthermal diodes.",
        "positive": "Raman Fingerprint of Pressure-Induced Phase Transitions in TiS3\n  Nanoribbons: Implications for Thermal Measurements under Extreme Stress\n  Conditions: Two-dimensional layered trichalcogenide materials have recently attracted the\nattention of the scientific community because of its robust mechanical, thermal\nproperties and applications in opto and nanoelectronics devices. We report the\npressure dependence of out-of plane Ag Raman modes in high quality few-layers\ntitanium trisulfide (TiS3) nanoribbons grown using a direct solid-gas reaction\nmethod and infer their cross-plane thermal expansion coefficient.Both\nmechanical stability and thermal properties of the TiS3 nanoribbons are\nelucidated using phonon-spectrum analyses. Raman spectroscopic studies at high\npressure (up to 34 GPa) using a diamond anvil cell identify four prominent Ag\nRaman bands; a band at 557 cm-1 softens under compression, and others at 175,\n300, and 370 cm-1 show normal hardening. Anomalies in phonon mode frequencies\nand excessive broadening in line-width of the soft phonon about ~ 13 GPa are\nattributed to the possible onset of a reversible structural transition. A\ncomplete structural phase transition at 43 GPa is inferred from Ag soft mode\nfrequency (557 cm-1) versus pressure extrapolation curve, consistent with\nrecent reported theoretical predictions. Using the experimental mode\nGr\\\"uneisen parameters i of Raman modes, the cross-plane thermal expansion\ncoefficient Cv of the TiS3 nanoribbons at ambient phase is estimated to\nbe1.32110-6K-1. The observed results are expected to be useful in calibration\nand performance of next generation nano-electronics and optical devices under\nextreme stress conditions."
    },
    {
        "anchor": "Incommensurate atomic and magnetic modulations in the spin-frustrated\n  \u03b2-NaMnO2 triangular lattice: The layered {\\beta}-NaMnO2, a promising Na-ion energy-storage material has\nbeen investigated for its triangular lattice capability to promote complex\nmagnetic configurations that may release symmetry restrictions for the\ncoexistence of ferroelectric and magnetic orders. The complexity of the neutron\npowder diffraction patterns underlines that the routinely adopted commensurate\nstructural models are inadequate. Instead, a single-phase superspace symmetry\ndescription is necessary, demonstrating that the material crystallizes in a\ncompositionally modulated q= (0.077(1), 0, 0) structure. Here, Mn3+ Jahn-Teller\ndistorted MnO6 octahedra form corrugated layer stacking sequences of the\n{\\beta}-NaMnO2 type, which are interrupted by flat sheets of the {\\alpha}-like\noxygen topology. Spontaneous long-range collinear antiferromagnetic order,\ndefined by the propagation vector k= (1/2, 1/2, 1/2), appears below TN1= 200 K.\nMoreover, a second transition into a spatially modulated proper-screw magnetic\nstate (k+-q) is established at TN2= 95 K, with an antiferromagnetic order\nparameter resembling that of a two-dimensional (2D) system. The evolution of\n23Na NMR spin-lattice relaxation identifies a magnetically inhomogene-ous state\nin the intermediate T-region (TN2 <T< TN1), while its strong suppression below\nTN2 indicates that a spin-gap opens in the excitation spectrum. High-resolution\nneutron inelastic scattering confirms that the magnetic dynamics are indeed\ngapped ({\\Delta}~5 meV) in the low-temperature magnetic phase, while\nsimulations on the basis of the single-mode approximation suggest that Mn-spins\nresiding on ad-jacent antiferromagnetic chains, establish sizable 2D\ncorrelations. Our analysis points that novel struc-tural degrees of freedom\npromote, cooperative magnetism and emerging dielectric properties in this\nnon-perovskite-type of manganite.",
        "positive": "Test of a theoretical equation of state for elemental solids and liquids: We propose a means for constructing highly accurate equations of state (EOS)\nfor elemental solids and liquids essentially from first principles, based upon\na particular decomposition of the underlying condensed matter Hamiltonian for\nthe nuclei and electrons. We also point out that at low pressures the neglect\nof anharmonic and electron-phonon terms, both contained in this formalism,\nresults in errors of less than 5% in the thermal parts of the thermodynamic\nfunctions. Then we explicitly display the forms of the remaining terms in the\nEOS, commenting on the use of experiment and electronic structure theory to\nevaluate them. We also construct an EOS for Aluminum and compare the resulting\nHugoniot with data up to 5 Mbar, both to illustrate our method and to see\nwhether the approximation of neglecting anharmonicity et al. remains viable to\nsuch high pressures. We find a level of agreement with experiment that is\nconsistent with the low-pressure results."
    },
    {
        "anchor": "Crystallographic ordering of Al and Sn in \u03b1-Ti: Increasing attention is being paid to $\\alpha$$_2$ Ti$_3$(Al,Sn)\nprecipitation from the $\\alpha$ phase of titanium alloys owing to its effect on\nslip band formation, localisation and the implications for fatigue performance\nin jet engine titanium. However, the early stages of $\\alpha$$_2$ precipitation\nhave historically been difficult to observe in TEM, neutron diffraction or atom\nprobe analysis. Here, small angle X-ray scattering is used to reexamine the\nphase boundary in binary Ti-Al and Ti-Sn alloys with around 500 ppmw O. It is\nfound that the phase boundaries in the literature are approximately correct, at\n6.2 wt.% Al and 16.9 wt.% Sn, and that this favours the use of Al as a solid\nsolution strengthener over Sn for ambient temperature applications. However,\nonce O content and phase partitioning in $\\alpha$+$\\beta$ alloys are taken into\naccount, this implies that Al$_{eq}$ limits for future alloy design of critical\nrotating parts should be lowered substantially.",
        "positive": "Device for in-situ cleaving of hard crystals: Cleaving crystals in a vacuum chamber is a simple method for obtaining\natomically flat and clean surfaces for materials that have a preferential\ncleaving plane. Most in-situ cleavers use parallel cutting edges that are\napplied from two sides on the sample. We found in ambient experiments that\ndiagonal cutting pliers, where the cleavage force is introduced in a single\npoint instead of a line work very well also for hard materials. Here, we\nincorporate the diagonal cutting plier principle in a design compatible with\nultra-high vacuum requirements. We show optical microscopy (mm scale) and\natomic force microscopy (atomic scale) images of NiO(001) surfaces cleaved with\nthis device."
    },
    {
        "anchor": "Displacive model of deformation twinning in hexagonal close-packed\n  metals. Case of the (90 deg, a) and (86 deg, a) extension twins in magnesium: A crystallographic displacive model is proposed for the extension twins in\nmagnesium. It is based on a hard-sphere assumption previously used for\nmartensitic transformations. The atomic displacements are established, and the\nhomogeneous lattice distortion is analytically expressed as a continuous\nangular-distortive matrix that takes the usual form of shear when the\ndistortion is complete. The calculations prove that a volume change of 3\npercents occurs for the intermediate states and that the twinning plane, even\nif untilted and restored when the distortion is complete, is not fully\ninvariant during the transient states. The crystallographic calculations also\nshow that the (90 deg, a) twins observed in magnesium nano-pillars and the (86\ndeg, a) twins observed in bulk samples come from the same mechanism, the only\ndifference being the existence of a slight obliquity angle (+/- 3.4 deg)\nrequired to reduce the strains in the latter case. Continuous features in the\npole figures between the low-misoriented (86 deg, a) twin variants are\nexpected; they are confirmed by EBSD maps acquired on a deformed magnesium\nsingle crystal. As the continuous mechanism of extension twinning is not a\nsimple shear, a \"virtual work\" criterion using the value of the intermediate\ndistortion matrix at the maximum volume change is proposed in place of the\nusual Schmid's law. It allows predicting the formation of extension twins for\ncrystal orientations associated with negative Schmid factors.",
        "positive": "Brownian reservoir computing realized using geometrically confined\n  skyrmions: Reservoir computing (RC) has been considered as one of the key computational\nprinciples beyond von-Neumann computing. Magnetic skyrmions, topological\nparticle-like spin textures in magnetic films are particularly promising for\nimplementing RC, since they respond strongly nonlinear to external stimuli and\nfeature inherent multiscale dynamics. However, despite several theoretical\nproposals that exist for skyrmion reservoir computing, experimental\nrealizations have been elusive until now. Here, we propose and experimentally\ndemonstrate a conceptually new approach to skyrmion RC that leverages the\nthermally activated diffusive motion of skyrmions. By confining the\nelectrically gated and thermal skyrmion motion, we find that already a single\nskyrmion in a confined geometry suffices to realize non-linearly separable\nfunctions, which we demonstrate for the XOR gate along with all other Boolean\nlogic gate operations. Besides this universality, the reservoir computing\nconcept ensures low training costs and ultra-low power operation with current\ndensities orders of magnitude smaller than those used in existing spintronic\nreservoir computing demonstrations. Our proposed concept can be readily\nextended by linking multiple confined geometries and/or by including more\nskyrmions in the reservoir, suggesting high potential for scalable and\nlow-energy reservoir computing."
    },
    {
        "anchor": "First-principles quantum corrections for carrier correlations in\n  double-layer two-dimensional heterostructures: We present systematic ab initio calculations of the charge carrier\ncorrelations between adjacent layers of two-dimensional materials in the\npresence of both charged impurity and strain disorder potentials using the\nexamples of monolayer and bilayer graphene. For the first time, our analysis\nyields unambiguous first-principles quantum corrections to the Thomas--Fermi\ndensities for interacting two-dimensional systems described by orbital-free\ndensity functional theory. Specifically, using density-potential functional\ntheory, we find that quantum corrections to the quasi-classical Thomas-Fermi\napproximation have to be taken into account even for heterostructures of\nmesoscopic size. In order for the disorder-induced puddles of electrons and\nholes to be anti-correlated at zero average carrier density for both layers,\nthe strength of the strain potential has to exceed that of the impurity\npotential by at least a factor of ten, with this number increasing for smaller\nimpurity densities. Furthermore, our results show that quantum corrections have\na larger impact on puddle correlations than exchange does, and they are\nnecessary for properly predicting the experimentally observed Gaussian energy\ndistribution at charge neutrality.",
        "positive": "Landau level splitting in Cd3As2 under high magnetic fields: Three-dimensional topological Dirac semimetals (TDSs) are a new kind of Dirac\nmaterials that exhibit linear energy dispersion in the bulk and can be viewed\nas three-dimensional graphene. It has been proposed that TDSs can be driven to\nother exotic phases like Weyl semimetals, topological insulators and\ntopological superconductors by breaking certain symmetries. Here we report the\nfirst transport experiment on Landau level splitting in TDS Cd3As2 single\ncrystals under high magnetic fields, suggesting the removal of spin degeneracy\nby breaking time reversal symmetry. The detected Berry phase develops an\nevident angular dependence and possesses a crossover from nontrivial to trivial\nstate under high magnetic fields, a strong hint for a fierce competition\nbetween the orbit-coupled field strength and the field-generated mass term. Our\nresults unveil the important role of symmetry breaking in TDSs and further\ndemonstrate a feasible path to generate a Weyl semimetal phase by breaking time\nreversal symmetry."
    },
    {
        "anchor": "Accelerated Carrier Recombination by Grain Boundary/Edge Defects in MBE\n  Grown Transition Metal Dichalcogenides: Defect-carrier interaction in transition metal dichalcogenides (TMDs) play\nimportant roles in carrier relaxation dynamics and carrier transport, which\ndetermines the performance of electronic devices. With femtosecond laser\ntime-resolved spectroscopy, we investigated the effect of grain boundary/edge\ndefects on the ultrafast dynamics of photoexcited carrier in MBE grown MoTe2\nand MoSe2. We found that, comparing with exfoliated samples, carrier\nrecombination rate in MBE grown samples accelerates by about 50 times. We\nattribute this striking difference to the existence of abundant grain\nboundary/edge defects in MBE grown samples, which can serve as effective\nrecombination centers for the photoexcited carriers. We also observed coherent\nacoustic phonons in both exfoliated and MBE grown MoTe2, indicating strong\nelectron-phonon coupling in this materials. Our measured sound velocity agrees\nwell with previously reported result of theoretical calculation. Our findings\nprovide useful reference for the fundamental parameters: carrier lifetime and\nsound velocity, reveal the undiscovered carrier recombination effect of grain\nboundary/edge defects, both of which will facilitate the defect engineering in\nTMD materials for high speed opto-electronics.",
        "positive": "Large-scale machine-learning-assisted exploration of the whole materials\n  space: Crystal-graph attention networks have emerged recently as remarkable tools\nfor the prediction of thermodynamic stability and materials properties from\nunrelaxed crystal structures. Previous networks trained on two million\nmaterials exhibited, however, strong biases originating from underrepresented\nchemical elements and structural prototypes in the available data. We tackled\nthis issue computing additional data to provide better balance across both\nchemical and crystal-symmetry space. Crystal-graph networks trained with this\nnew data show unprecedented generalization accuracy, and allow for reliable,\naccelerated exploration of the whole space of inorganic compounds. We applied\nthis universal network to perform machine-learning assisted high-throughput\nmaterials searches including 2500 binary and ternary structure prototypes and\nspanning about 1 billion compounds. After validation using density-functional\ntheory, we uncover in total 19512 additional materials on the convex hull of\nthermodynamic stability and ~150000 compounds with a distance of less than 50\nmeV/atom from the hull. Combining again machine learning and ab-initio methods,\nwe finally evaluate the discovered materials for applications as\nsuperconductors, superhard materials, and we look for candidates with large gap\ndeformation potentials, finding several compounds with extreme values of these\nproperties."
    },
    {
        "anchor": "Electronic nature of coverage-dependent nanosurface effect by\n  cooperative orbital redistribution: Nanomaterial surface states can effectively modify or even dominate their\nphysical and chemical properties due to large surface-to-volume ratios. Such\nsurface effects are highly dependent on particle size and ligand coverage, yet\nthe underlying electronic-level mechanism still remains unknown. Using TiO2\nnanosheet as a model system, we reveal the electronic nature of\ncoverage-dependent nanosurface effects through varying ligand coverage and\nprobing the modified surface bonding and electronic band structures with\nnear-edge X-ray absorption fine structure. We discover experimentally that\nsurface ligands can competitively polarize the 3d orbitals of surface Ti atoms\ninto chemisorption states, which is cooperative with increased ligand\ncoverages. Such coverage-dependent cooperative orbital redistribution accounts\nfor various nanosurface effects on regulating the electronic structure, surface\nreactivity, optical property, and chemisorption of nanomaterials.",
        "positive": "Nonvolatile Static Random Access Memory (NV-SRAM) Using Magnetic Tunnel\n  Junctions with Current-Induced Magnetization Switching Architecture: We propose and computationally analyze a nonvolatile static random access\nmemory (NV-SRAM) cell using magnetic tunnel junctions (MTJs) with\nmagnetic-field-free current-induced magnetization switching (CIMS)\narchitecture. A pair of MTJs connected to the storage nodes of a standard SRAM\ncell with CIMS architecture enables fully electrical store and restore\noperations for nonvolatile logic information. The proposed NV-SRAM is expected\nto be a key component of next-generation power-gating logic systems with\nextremely low static-power dissipation."
    },
    {
        "anchor": "One-shot calculation of temperature-dependent optical spectra and\n  phonon-induced band-gap renormalization: Recently, Zacharias et al [Phys. Rev. Lett. 115, 177401 (2015)] developed a\nnew ab initio theory of temperature-dependent optical absorption spectra and\nband gaps in semiconductors and insulators. In that work the zero-point\nrenormalization and the temperature dependence were obtained by sampling the\nnuclear wavefunctions using a stochastic approach. In the present work, we show\nthat the stochastic sampling can be replaced by fully deterministic supercell\ncalculations based on a single optimal configuration of the atomic positions.\nWe demonstrate that a single calculation is able to capture the\ntemperature-dependent band gap renormalization including quantum nuclear\neffects in direct and indirect-gap semiconductors, as well as phonon-assisted\noptical absorption in indirect-gap semiconductors. In order to demonstrate this\nmethodology we calculate from first principles the temperature-dependent\noptical absorption spectra and the renormalization of direct and indirect band\ngaps in Si, C, and GaAs, and we obtain good agreement with experiment and with\nprevious calculations. In this work we also establish the formal connection\nbetween the Williams-Lax theory of optical transitions and the related theories\nof indirect absorption by Hall, Bardeen, and Blatt, and of\ntemperature-dependent band structures by Allen and Heine. Furthermore, we\nidentify an additional band gap renormalization that arises in the case of\ndegenerate band extrema, and which has not been considered in previous work.\nThe present methodology enables systematic ab initio calculations of optical\nabsorption spectra at finite temperature, including both direct and indirect\ntransitions. This feature will be useful for high-throughput calculations of\noptical properties at finite temperature, and for calculating\ntemperature-dependent optical properties using high-level theories such as GW\nand Bethe-Salpeter approaches.",
        "positive": "Anomalous transient blueshift in the internal stretch mode of CO/Pd(111): In time-resolved pump-probe vibrational spectroscopy the internal stretch\nmode of polar molecules is utilized as a key observable to characterize the\nultrafast dynamics of adsorbates on surfaces. The adsorbates non-adiabatic\nintermode couplings are the commonly accepted mechanisms behind the observed\ntransient frequency shifts. Here, we study the CO/Pd(111) system with a robust\ntheoretical framework that includes electron-hole pair excitations and\nelectron-mediated coupling between the vibrational modes. A mechanism is\nrevealed that screens the electron-phonon interaction and originates a\nblueshift under ultrafast non-equilibrium conditions. The results are explained\nin terms of the abrupt change in the density of states around the Fermi level,\nand are instrumental for understanding dynamics at multi-component surfaces\ninvolving localized and standard $s$ or $p$ states."
    },
    {
        "anchor": "Cohesive and magnetic properties of grain boundaries in bcc Fe with Cr\n  additions: Structural, cohesive, and magnetic properties of two symmetric $\\Sigma3(111)$\nand $\\Sigma5(210)$ tilt grain boundaries (GBs) in pure bcc Fe and in dilute\nFeCr alloys are studied from first principles. Different concentration and\nposition of Cr solute atoms are considered. We found that Cr atoms placed in\nthe GB interstice enhance the cohesion by 0.5-1.2 J/m$^2$. Substitutional Cr in\nthe layers adjacent to the boundary shows anisotropic effect on the GB\ncohesion: it is neutral when placed in the (111) oriented Fe grains, and\nenhances cohesion (by 0.5 J/m$^2$) when substituted in the boundary layer of\nthe (210) grains. The strengthening effect of the Cr solute is dominated by the\nchemical component of the adhesive binding energy. Our calculations show that\nunlike the free iron surfaces, Cr impurities segregate to the boundaries of the\nFe grains. The magnetic moments on GB atoms are substantially changed and their\nvariation correlates with the corresponding relaxation pattern of the GB\nplanes. The moments on Cr additions are 2-4 times enhanced in comparison with\nthat in a Cr crystal and are antiparallel to the moments on the Fe atoms.",
        "positive": "Size Distribution and Its Scaling Behavior of InAlAs/AlGaAs Quantum Dots\n  Grown on GaAs by Molecular Beam Epitaxy: We studied the size distribution and its scaling behavior of self-assembled\nInAlAs/AlGaAs quantum dots (QDs) grown on GaAs with the Stranski-Krastanov (SK)\nmode by molecular beam epitaxy (MBE), at both 480{\\deg}C and 510{\\deg}C, as a\nfunction of InAlAs coverage. A scaling function of the volume was found for the\nfirst time in ternary alloy QDs. The function was similar to that of InAs/GaAs\nQDs, which agreed with the scaling function for the two-dimensional\nsubmonolayer homoepitaxy simulation with a critical island size of i = 1.\nHowever, a character of i = 0 was also found as a tail in the large volume."
    },
    {
        "anchor": "Mean Transverse Energy of Ultrananocrystalline Diamond Photocathode: Nitrogen incorporated ultrananocrystalline diamond ((N)UNCD) could be an\nenabling material platform for photocathode applications due to its high\nemissivity. While the quantum efficiency (QE) of UNCD was reported by many\ngroups, no experimental measurements of the intrinsic emittance/mean transverse\nenergy (MTE) have been reported. Here, MTE measurement results for an (N)UNCD\nphotocathode in the photon energy range of 4.41 to 5.26 eV are described. The\nMTE demonstrates no noticeable dependence on the photon energy, with an average\nvalue of 266 meV. This spectral behavior is shown to not to be dependent upon\nphysical or chemical surface roughness and inconsistent with low electron\neffective mass emission from graphitic grain boundaries, but may be associated\nwith emission from spatially-confined states in the graphite regions between\nthe diamond grains. The combined effect of fast-growing QE and constant MTE\nwith respect to the excess laser energy may pave the way to bright UNCD\nphotocathodes.",
        "positive": "Control of the magnetic anisotropy in multi-repeat Pt/Co/Al\n  heterostructures using magneto-ionic gating: Controlling magnetic properties through the application of an electric field\nis a significant challenge in modern nanomagnetism. In this study, we\ninvestigate the magneto-ionic control of magnetic anisotropy in the topmost Co\nlayer in Ta/Pt/[Co/Al/Pt]$_n$/Co/Al/AlO$_\\text{x}$ multilayer stacks comprising\n$n +1$ Co layers and its impact on the magnetic properties of the multilayers.\nWe demonstrate that the perpendicular magnetic anisotropy can be reversibly\nquenched through gate-driven oxidation of the intermediary Al layer between Co\nand AlO$_\\text{x}$, enabling dynamic control of the magnetic layers\ncontributing to the out-of-plane remanence - varying between $n$ and $n +1$.\nFor multilayer configurations with $n = 2$ and $n = 4$, we observe reversible\nand non-volatile additions of 1/3 and 1/5, respectively, to the anomalous Hall\neffect amplitude based on the applied gate voltage. Magnetic imaging reveals\nthat the gate-induced spin-reorientation transition occurs through the\npropagation of a single 90$^{\\circ}$ magnetic domain wall separating the\nperpendicular and in-plane anisotropy states. In the 5-repetition multilayer,\nthe modification leads to a doubling of the period of the magnetic domains at\nremanence. These results demonstrate that the magneto-ionic control of the\nanisotropy of a single magnetic layer can be used to control the magnetic\nproperties of coupled multilayer systems, extending beyond the gating effects\non a single magnetic layer."
    },
    {
        "anchor": "A model for spin-polarized transport in perovskite manganite bi-crystal\n  grain boundaries: We have studied the temperature dependence of low-field magnetoresistance and\ncurrent-voltage characteristics of a low-angle bi-crystal grain boundary\njunction in perovskite manganite La_{2/3}Sr_{1/3}MnO_3 thin film. By gradually\ntrimming the junction we have been able to reveal the non-linear behavior of\nthe latter. With the use of the relation M_{GB} \\propto M_{bulk}\\sqrt{MR^*} we\nhave extracted the grain boundary magnetization. Further, we demonstrate that\nthe built-in potential barrier of the grain boundary can be modelled by\nV_{bi}\\propto M_{bulk}^2 - M_{GB}^2. Thus our model connects the\nmagnetoresistance with the potential barrier at the grain boundary region. The\nresults indicate that the band-bending at the grain boundary interface has a\nmagnetic origin.",
        "positive": "$\\textit{ab initio}$ description of bonding for transmission electron\n  microscopy: The simulation of transmission electron microscopy (TEM) images or\ndiffraction patterns is often required to interpret their contrast and extract\nspecimen features. This is especially true for high-resolution phase-contrast\nimaging of materials, but electron scattering simulations based on atomistic\nmodels are widely used in materials science and structural biology. Since\nelectron scattering is dominated by the nuclear cores, the scattering potential\nis typically described by the widely applied independent atom model. This\napproximation is fast and fairly accurate, especially for scanning TEM (STEM)\nannular dark-field contrast, but it completely neglects valence bonding and its\neffect on the transmitting electrons. However, an emerging trend in electron\nmicroscopy is to use new instrumentation and methods to extract the maximum\namount of information from each electron. This is evident in the increasing\npopularity of techniques such as 4D-STEM combined with ptychography in\nmaterials science, and cryogenic microcrystal electron diffraction in\nstructural biology, where subtle differences in the scattering potential may be\nboth measurable and contain additional insights. Thus, there is increasing\ninterest in electron scattering simulations based on electrostatic potentials\nobtained from first principles, mainly via density functional theory, which was\npreviously mainly required for holography. In this Review, we discuss the\nmotivation and basis for these developments, survey the pioneering work that\nhas been published thus far, and give our outlook for the future. We argue that\na physically better justified $\\textit{ab initio}$ description of the\nscattering potential is both useful and viable for an increasing number of\nsystems, and we expect such simulations to steadily gain in popularity and\nimportance."
    },
    {
        "anchor": "Near-field interaction between domain walls in adjacent Permalloy\n  nanowires: The magnetostatic interaction between two oppositely charged transverse\ndomain walls (DWs)in adjacent Permalloy nanowires is experimentally\ndemonstrated. The dependence of the pinning strength on wire separation is\ninvestigated for distances between 13 and 125 nm, and depinning fields up to 93\nOe are measured. The results can be described fully by considering the\ninteraction between the full complex distribution of magnetic charge within\nrigid, isolated DWs. This suggests the DW internal structure is not appreciably\ndisturbed by the pinning potential, and that they remain rigid although the\npinning strength is significant. This work demonstrates the possibility of\nnon-contact DW trapping without DW perturbation and full continuous flexibility\nof the pinning potential type and strength. The consequence of the interaction\non DW based data storage schemes is evaluated.",
        "positive": "The Quantum Energy Density: Improved Efficiency for Quantum Monte Carlo: We establish a physically meaningful representation of a quantum energy\ndensity for use in Quantum Monte Carlo calculations. The energy density\noperator, defined in terms of Hamiltonian components and density operators,\nreturns the correct Hamiltonian when integrated over a volume containing a\ncluster of particles. This property is demonstrated for a helium-neon \"gas,\"\nshowing that atomic energies obtained from the energy density correspond to\neigenvalues of isolated systems. The formation energies of defects or\ninterfaces are typically calculated as total energy differences. Using a model\nof delta-doped silicon (where dopant atoms form a thin plane) we show how\ninterfacial energies can be calculated more efficiently with the energy\ndensity, since the region of interest is small. We also demonstrate how the\nenergy density correctly transitions to the bulk limit away from the interface\nwhere the correct energy is obtainable from a separate total energy\ncalculation."
    },
    {
        "anchor": "Breakdown of Reye's theory in nanoscale wear: Building on an analogy to ductile fracture mechanics, we quantify the size of\ndebris particles created during adhesive wear. Earlier work suggested a linear\nrelation between tangential work and wear debris volume, assuming that the\ndebris size is proportional to the micro contact size multiplied by the\njunction shear strength. However, the present study reveals deviations from\nlinearity. These deviations can be rationalized with fracture mechanics and\nimply that less work is necessary to generate debris than what was assumed.\nHere, we postulate that the work needed to detach a wear particle is made of\nthe surface energy expended to create new fracture surfaces, and also of\nplastic work within a fracture process zone of a given width around the cracks.\nOur theoretical model, validated by molecular dynamics simulations, reveals a\nsuper-linear scaling relation between debris volume ($V_d$) and tangential work\n($W_t$): $V_d \\sim W_t^{3/2}$ in 3D and $V_d \\sim W_t^{2}$ in 2D. This study\nprovides a theoretical foundation to estimate the statistical distribution of\nsizes of fine particles emitted due to adhesive wear processes.",
        "positive": "Fermi-Surface Modeling of Light-Rare-Earth Hexaborides with 2D-ACAR\n  Spectroscopy: Two dimensional angular correlation of the positron annihilation radiation\n(2D-ACAR) spectra are measured for $\\mathrm{LaB}_6$ along high symmetry\ndirections and compared with first principle calculations based on density\nfunctional theory (DFT). This allows the modeling of the Fermi surface in terms\nof ellipsoid electron pockets centered at $X$-points elongated along the\n$\\Sigma$ axis (${\\Gamma-M}$ direction). The obtained structure is in agreement\nwith quantum oscillation measurements and previous band structure calculations.\nFor the isostructural topologically not-trivial $\\mathrm{SmB}_6$ the similar\nellipsoids are connected through necks that have significantly smaller radii in\nthe case of $\\mathrm{LaB}_6$. A theoretical analysis of the 2D-ACAR spectra is\nalso performed for $\\mathrm{CeB}_6$ including the on-site repulsion $U$\ncorrection to the local-density approximation (LDA+$U$) of the DFT. The\nsimilarities of 2D-ACAR spectra and the Fermi-surface projections of these two\ncompounds allow to infer that both $\\mathrm{LaB}_6$ and $\\mathrm{CeB}_6$ are\ntopologically trivial correlated metals."
    },
    {
        "anchor": "Genetic Programming for Multi-Timescale Modeling: A bottleneck for multi-timescale dynamics is the computation of the potential\nenergy surface (PES). We explore the use of genetic programming (GP) to\nsymbolically regress a mapping of the saddle-point barriers from only a few\ncalculated points via molecular dynamics, thereby avoiding explicit calculation\nof all the barriers. The GP-regressed barrier function enables use of kinetic\nMonte Carlo (KMC) to simulate real-time kinetics (seconds to hours) using\nrealistic interactions. To illustrate, we apply a GP regression to\nvacancy-assisted migration on a surface of a binary alloy and predict the\ndiffusion barriers within 0.1--1% error using 3% (or less) of the barriers, and\ndiscuss the significant reduction in CPU time.",
        "positive": "Statistical transfer rates associated with higher-symmetry\n  potential-energy wells in solids: Application to photoinduced desorption and\n  electrification: A current series of papers on barrier-controlled and trapping processes in\nsolids and/or at solid surfaces have laid down the emphasis onto describing the\nstatistical event by means of the barrier currents method due to Bardeen and\nChristov. The present study centered on photodesorption and\nphotoelectrification is the fourth of an arXiv series which also included rapid\nstatistical approaches to nucleation, diffusion and drift currents in state of\nthe art materials. We presently extend our arguments to spherical square and\noscillatory wells to deal with the photoprocesses."
    },
    {
        "anchor": "Multiplexed Multi-Color Raman Imaging of Live Cells with Isotopically\n  Modified Single Walled Carbon Nanotubes: We show that single walled carbon nanotubes with different isotope\ncompositions exhibit distinct Raman Gband peaks and can be used for multiplexed\nmulti-color Raman imaging of biological systems. Cancer cells with specific\nreceptors are selectively labeled with 3 differently colored SWNTs conjugated\nwith various targeting ligands including Herceptin, anti-Her2, Erbitux,\nanti-Her1, and RGD peptide, allowing for multi-color Raman imaging of cells in\na multiplexed manner. SWNT Raman signals are highly robust against\nphoto-bleaching, allowing long term imaging and tracking. With narrow peak\nfeatures, SWNT Raman signals are easily differentiated from the\nauto-fluorescence background. The SWNT Raman excitation and scattering photons\nare in the near-infrared region, which is the most transparent optical window\nfor biological systems in vitro and in vivo. Thus, SWNTs are novel Raman tags\npromising for multiplexed biological detection and imaging.",
        "positive": "Mechanical Stresses Estimation in Silicon and Glass Bonded at Elevated\n  Temperature: During electrostatic bonding, also known as anodic bonding, silicon is bonded\nto glass by applying an external voltage and simultaneous heating to\ntemperatures of 200...450 $\\deg$C. While cooling to working temperature after\nbonding happened pieces are mutually deformed. Due to linear thermal expansion\ncoefficients mismatch of anodically bonded glass and silicon samples an\ninternal stress state is generated. Such stresses are called thermal mismatch\nstresses. The aim of this paper is a determination of technological and design\nsolutions to achieve minimal thermal mismatch stresses in resulting bond.\n  The nonlinear dependence of linear thermal expansion coefficients of bonded\nsamples' materials on temperature makes it difficult to minimize thermal\nmismatch stresses by chosing materials with close average thermal expansion\ncoefficients in particular temperature range. To assess means of lowering\nthermal mismatch stress in this paper two different ways to describe assembly\nare used: two thin bonded layers and multilayered composite material.\n  Based on properties of two brands of glass (LK5, Borofloat 33) and silicon\nused with described mathematical models thermal mismatch stresses at\ntemperature $T_w$ in samples bonded at several different temperatures $T_b$ are\nevaluated. Bonded silicon surface stress dependence of glass to silicon wafer\nthickness ratio is evaluated. Based on such evaluations one can say that by\nvarying thickness of glass bonded to silicon one can obtain zero thermal\nmismatch stress at a particular depth of material or obtain stress of some\ndefined value at this depth.\n  Models of assembly description used in this paper can be used to optimize\nanodic bonding process parameters. Such usage aimed to minimize thermal\nmismatch stresses at device working temperatures is presented in this paper."
    },
    {
        "anchor": "Alloying Effects on the Microstructure and Properties of Laser\n  Additively Manufactured Tungsten Materials: A large body of literature within the additive manufacturing (AM) community\nhas focused on successfully creating stable tungsten (W) microstructures due to\nsignificant interest in its application for extreme environments. However,\nsolidification cracking and additional embrittling features at grain boundaries\nhave resulted in poorly performing microstructures, stymying the application of\nAM as a manufacturing technique for W. Several alloying strategies, such as\nceramic particles and ductile elements, have emerged with the promise to\neliminate solidification cracking while simultaneously enhancing stability\nagainst recrystallization. In this work, we provide new insights regarding the\ndefects and microstructural features that result from the introduction of ZrC\nfor grain refinement and NiFe as a ductile reinforcement phase - in addition to\nthe resulting thermophysical and mechanical properties. ZrC is shown to promote\nmicrostructural stability with increased hardness due to the formation of ZrO2\ndispersoids. Conversely, NiFe forms into micron-scale FCC phase regions within\na BCC W matrix, producing enhanced toughness relative to pure AM W. A\ncombination of these effects is realized in the WNiFe+ZrC system and\ndemonstrates that complex chemical environments coupled with the tuning of AM\nmicrostructures provides an effective pathway for enabling laser AM W materials\nwith enhanced stability and performance.",
        "positive": "Atomic-scale analysis of liquid-gallium embrittlement of aluminum grain\n  boundaries: In this work, we explore the role of atomistic-scale energetics on\nliquid-metal embrittlement of Al due to Ga. Ab initio and molecular mechanics\nwere employed to probe the binding energies of vacancies and segregation\nenergies of Ga for <100>, <110> and <111> STGBs in Al. We found that the GB\nlocal arrangements and resulting structural units have a significant influence\non the magnitude of vacancy binding energies. For example, the mean vacancy\nbinding energy for <100>, <110>, and <111> STGBs at 1st layer was found to be\n-0.63 eV, -0.26 eV, and -0.60 eV. However, some GBs exhibited vacancy binding\nenergies closer to bulk values, indicating interfaces with zero sink strength,\ni.e., these GBs may not provide effective pathways for vacancy diffusion. The\nresults from the present work showed that the GB structure and the associated\nfree volume also play significant roles in Ga segregation and the subsequent\nembrittlement of Al. The Ga mean segregation energy for <100>, <110> and <111>\nSTGBs at 1st layer was found to be -0.23 eV, -0.12 eV and -0.24 eV,\nrespectively, suggesting a stronger correlation between the GB structural unit,\nits free volume, and segregation behavior. Furthermore, as the GB free volume\nincreased, the difference in segregation energies between the 1st layer and the\n0th layer increased. Thus, the GB character and free volume provide an\nimportant key to understanding the degree of anisotropy in various systems. The\noverall characteristic Ga absorption length scale was found to be about ~10, 8,\nand 12 layers for <100>, <110>, and <111> STGBs, respectively. Also, a few GBs\nof different tilt axes with relatively high segregation energies (between 0 and\n-0.1 eV) at the boundary were also found. This finding provides a new atomistic\nperspective to the GB engineering of materials with smart GB networks to\nmitigate or control LME and more general embrittlement phenomena in alloys."
    },
    {
        "anchor": "An upper bound to multiscale roughness-induced adhesion enhancement: Recently Guduru and coworkers have demonstrated with neat theory and\nexperiments that both increase of strength and of toughness are possible in the\ncontact of a rigid sphere with concentric single scale of waviness, against a\nvery soft material. The present note tries to answer the question of a\nmultiscale enhancement of adhesion, considering a Weierstrass series to\nrepresent the multiscale roughness, and analytical results only are used. It is\nconcluded that the enhancement is bounded for low fractal dimensions but it can\nhappen, and possibly to very high values, whereas it is even unbounded for high\nfractal dimensions, but it is also much less likely to occur, because of\nseparated contacts.",
        "positive": "Anomalous Nernst effect in Mn$_3$NiN thin films: The observation of a sizable anomalous Hall effect in magnetic materials with\nvanishing magnetization has renewed interest in understanding and engineering\nthis phenomenon. Antiferromagnetic antiperovskites are one of emerging material\nclasses that exhibit a variety of interesting properties owing to a complex\nelectronic band structure and magnetic ordering. Reports on the anomalous\nNernst effect and its magnitude in this class of materials are, however, very\nlimited. This scarcity may be partly due to the experimental difficulty of\nreliably quantifying the anomalous Nernst coefficient. Here, we report\nexperiments on the anomalous Nernst effect in antiferromagnetic antiperovskite\nMn$_3$NiN thin films. Measurement of both the anomalous Hall and Nernst effects\nusing the same sample and measurement geometry makes it possible to directly\ncompare these two effects and quantify the anomalous Nernst coefficient and\nconductivity in Mn$_3$NiN. We carefully evaluate the spatial distribution of\nthe thermal gradient in the sample and use finite element modeling to\ncorroborate our experimental results."
    },
    {
        "anchor": "Influence of Heat Treatment on the Corrosion Behavior of Purified\n  Magnesium and AZ31 Alloy: Magnesium and its alloys are ideal for biodegradable implants due to their\nbiocompatibility and their low-stress shielding. However, they can corrode too\nrapidly in the biological environment. The objective of this research was to\ndevelop heat treatments to slow the corrosion of high purified magnesium and\nAZ31 alloy in simulated body fluid at 37{\\deg}C. Heat treatments were performed\nat different temperatures and times. Hydrogen evolution, weight loss, PDP, and\nEIS methods were used to measure the corrosion rates. Results show that heat\ntreating can increase the corrosion resistance of HP-Mg by 2x and AZ31 by 10x.",
        "positive": "Ferroelectric thermal phase transition and polarization precursor\n  dynamics in CaxBa1-xNb2O6(CBN) tungsten bronze type oxides: Polycrystals of CaxBa1-xNb2O6(CBN) tungsten bronze type oxides have been\nprepared and their structural, dielectric, and thermal properties have been\ninvestigated. It was found that CBN alloys with ferroelectric tetragonal\ntungsten bronze structure were only available in a composition range of 0.19 <=\nx <= 0.32. It was also showed that CBN can be classified as a ferroelectric\nwith a first-order thermal phase transition showing polarization precursor\ndynamics before transition into the ferroelectric phase, in sharp contrast to\nan isostructural alloy SrxBa1-xNb2O6(SBN) that shows typical relaxor behaviors.\nThe local polarizations were found to grow exponentially within the\nparaelectric mother phase in a large temperature range of Tc<T<Tc+ 88~140 K on\ncooling. Furthermore, a phase diagram was established for CBN ferroelectric\nalloys. These findings may get an insight into the true nature of ferroelectric\nphase transition in this potential electro-optic material."
    },
    {
        "anchor": "Full Band Structure Calculation of Two-photon Indirect Absorption in\n  Bulk Silicon: Degenerate two-photon indirect absorption in silicon is an important limiting\neffect on the use of silicon structures for all-optical information processing\nat telecommunication wavelengths. We perform a full band structure calculation\nto investigate two-photon indirect absorption in bulk silicon, using a\npseudopotential description of the energy bands and an adiabatic bond charge\nmodel to describe phonon dispersion and polarization. Our results agree well\nwith some recent experimental results. The transverse acoustic/optical\nphonon-assisted processes dominate.",
        "positive": "Application of Cluster Variation and Path Probability Methods to the\n  Tetragonal-Cubic Phase Transition in ZrO2: Cluster variation method (CVM) and path probability method (PPM) have\ngenerally been employed to study replacive phase transitions in alloy systems.\nRecently, displacive phase transitions have been explored within the realm of\nreplacive phase transition in the CVM theoretical framework by viewing\ndisplaced atoms as different atomic species, i.e., by converting a freedom of\natomic displacement to a configurational freedom. The same methodology is\napplied to the PPM calculations in this work, and the kinetics of displacive\nphase transition from tetragonal to cubic phases in ZrO2 are investigated as\nwell as their equilibrium states."
    },
    {
        "anchor": "Ferromagnetic Mn doped InSb studied at the atomic scale by\n  cross-sectional STM: We present an atomically resolved study of metal-organic vapor epitaxy grown\nMn doped InSb that is ferromagnetic at room-temperature. Both topographic and\nspectroscopic measurements have been performed by cross-sectional scanning\ntunneling microscopy. The measurements show a perfect crystal structure without\nany precipitates and reveal that Mn acts as a shallow acceptor. The Mn\nconcentration obtained from the cross-sectional STM data compares well with the\nintended doping concentration. No second phase material or (nano)clustering of\nthe Mn was observed. While the pair correlation function of the Mn atoms showed\nthat their local distribution is uncorrelated beyond the STM resolution for\nobserving individual dopants, disorder in the Mn ion location is clearly noted.\nWe discuss the implications of the observed disorder for a number of suggested\nexplanations of the room-temperature ferromagnetism in Mn doped InSb grown by\nmetal-organic vapor epitaxy.",
        "positive": "Universal gapless Dirac cone and tunable topological states in\n  (MnBi$_2$Te$_4$)$_m$(Bi$_2$Te$_3$)$_n$ heterostructures: In the newly discovered magnetic topological insulator MnBi$_2$Te$_4$, both\naxion insulator state and quantized anomalous Hall effect (QAHE) have been\nobserved by tuning the magnetic structure. The related\n(MnBi$_2$Te$_4$)$_m$(Bi$_2$Te$_3$)$_n$ heterostructures with increased tuning\nknobs, are predicted to be a more versatile platform for exotic topological\nstates. Here, we report angle-resolved photoemission spectroscopy (ARPES)\nstudies on a series of the heterostructures (MnBi$_2$Te$_4$, MnBi$_4$Te$_7$ and\nMnBi$_6$Te$_{10}$). A universal gapless Dirac cone is observed at the\nMnBi$_2$Te$_4$ terminated (0001) surfaces in all systems. This is in sharp\ncontrast to the expected gap from the original antiferromagnetic ground state,\nindicating an altered magnetic structure near the surface, possibly due to the\nsurface termination. In the meantime, the electron band dispersion of the\nsurface states, presumably dominated by the top surface, is found to be\nsensitive to different stackings of the underlying MnBi$_2$Te$_4$ and\nBi$_2$Te$_3$ layers. Our results suggest the high tunability of both magnetic\nand electronic structures of the topological surface states in\n(MnBi$_2$Te$_4$)$_m$(Bi$_2$Te$_3$)$_n$ heterostructures, which is essential in\nrealizing various novel topological states."
    },
    {
        "anchor": "Non-magnetic doping induced magnetism in Li doped SnO2 nanoparticles: We address the possibility of non-magnetic doping induced magnetism, in Li\ndoped SnO2 nano-particles. The compounds have been prepared by solid state\nroute at equilibrium and were found to be crystallized in single rutile phase.\nThe magnetization measurements have shown that Li-doping induces magnetism in\nSnO2 for a particular range of Li concentration. However, for other Li\nconcentrations, including pure SnO2, the samples exhibit diamagnetism. To\ninvestigate the possible origin of the induced magnetism, we have studied the\nvariation of the magnetization as a function of the average nano-particle\nradius. Possible scenarios for the appearance of magnetism in these compounds\nare discussed.",
        "positive": "Large-scale multiscale modeling of phase transformation in\n  nanocrystalline materials: Atomistic and Phase-Field methods: In this research, atomistic molecular dynamics simulations are combined with\nmesoscopic phase-field computational methods in order to investigate\nphase-transformation in polycrystalline Aluminum microstructure. In fact,\nmicrostructural computational modeling of engineering materials could help to\noptimize their mechanical properties for industrial applications (e.g.\ndirectional solidification for turbine blades). As a result, a multiscale\nmodeling approach is developed to find a relation between manufacturing\nvariables (e.g. temperature) and microstructural properties of crystalline\nmaterials (e.g. grain size), which could be used to develop an advanced\nmanufacturing process for sensitive applications. The results show that\natomistic modeling of grain growth could be used as a first-principle approach\nin order to study phase transformation's kinetics, which could capture\nmorphology of polycrystalline materials more accurately. On the other hand,\nphase-field mesoscopic approach needs less computational efforts, but still it\nrelies on semi-empirical data to capture accurate phase transformation regimes,\nwhich makes this approach suitable for rapid examining of new manufacturing\nconditions as well as its effects on microstructural properties of\npolycrystalline materials."
    },
    {
        "anchor": "Atomistic spin model of single pulse toggle switching in Mn$_2$Ru$_x$Ga\n  Heusler alloys: Single femtosecond pulse toggle switching of ferrimagnetic alloys is an\nessential building block for ultrafast spintronics. Very different\nelement-specific demagnetization dynamics is believed to be a hard limit for\nswitching in ferrimagnets. This suggests that ferrimagnets composed of two ions\nof different nature, such as rare earth transition metal alloys, are necessary\nfor switching. However, experimental observation of toggle switching in\nMn$_2$Ru$_x$Ga Heusler alloys, has contested this limit since Mn ions are of\nthe same nature. To shed some light into this question, we present an atomistic\nspin model for the simulation of single pulse toggle switching of\nMn$_2$Ru$_x$Ga. The magnetic parameters entering in our model are extracted\nfrom previous experimental observations. We show that our model is able to\nquantitatively reproduce measured magnetization dynamics of single pulse toggle\nswitching. We demonstrate that differently to previous understanding toggle\nswitching in Mn$_2$Ru$_x$Ga is possible even when both Mn sublattices\ndemagnetization at very similar rate.",
        "positive": "Magnetic order in the computational 2D materials database (C2DB) from\n  high throughput spin spiral calculations: We report a detailed investigation of the magnetic order in 192 stable\nmagnetic two-dimensional materials from the Computational 2D Materials Database\nhaving one magnetic atom in the unit cell. The calculations are based on a\nsystematic workflow that employs spin spiral calculations and yields the\nmagnetic order in terms of a two-dimensional ordering vector $\\mathbf{Q}$. We\nthen include spin-orbit coupling to extract the easy and hard axes for\ncollinear structures and the orientation of spiral planes in non-collinear\nstructures. Finally, for all predicted ferromagnets we compute the\nDzyaloshinskii-Moriya interactions and determine whether or not these are\nstrong enough to overcome the magnetic anisotropy and stabilise a chiral spin\nspiral ground state. These steps completely determines the ground state order\nwithin the spiralling ansatz. We find 58 ferromagnets, 21 collinear\nanti-ferromagnets, and 85 non-collinear ground states of which 15 are chiral\nspin spirals driven by Dzyaloshinskii-Moriya interactions. The results show\nthat non-collinear order is in fact as common as collinear order in these\nmaterials and emphasise the need for detailed investigation of the magnetic\nground state when reporting magnetic properties of new materials. Furthermore,\nnon-collinear order typically breaks symmetries inherent to the lattice and may\ngive rise to emergent properties such as multiferroicity, magnetoelectricity or\nsecond order optical effects that would be predicted as absent based on a\ncollinear assumption."
    },
    {
        "anchor": "Optimization of criteria for an efficient screening of new\n  thermoelectric compounds: the TiNiSi structure type as a case-study: High-throughput calculations are a very promising tool for screening a large\nnumber of compounds in order to discover new useful materials. Ternary\nintermetallic are thus investigated in the present work to find new compounds\npotentially interesting for thermoelectric applications. The screening of the\nstable non-metallic compounds required for such applications is obtained by\ncalculating their electronic structure by DFT methods. In a first part, the\nstudy of the density of states at the Fermi level of well-known chemical\nelements and binary compounds allows to empirically optimize the selection\ncriteria between metals and non-metals. In a second part, the TiNiSi\nstructure-type is used as a case-study through the investigation of 570\npossible compositions. This screening method leads to the selection of 12\npossible semiconductors. For these selected compounds, their Seebeck\ncoefficient and their lattice thermal conductivity are calculated in order to\nidentify the most interesting one. TiNiSi, TaNiP or HfCoP could thus be\ncompounds worth an experimental investigation.",
        "positive": "High-Performance Monolayer WS2 Field-effect Transistors on High-k\n  Dielectrics: The combination of high-quality Al2O3 dielectric and thiol chemistry\npassivation can effectively reduce the density of interface traps and Coulomb\nimpurities of WS2, leading to a significant improvement of the mobility and a\ntransition of the charge transport from the insulating to the metallic regime.\nA record high mobility of 83 cm2/Vs (337 cm2/Vs) is reached at room temperature\n(low temperature) for monolayer WS2. A theoretical model for electron transport\nis also developed."
    },
    {
        "anchor": "Modeling low energy sputtering of hexagonal boron nitride by xenon ions: The sputtering of hexagonal boron nitride due to low energy xenon ion\nbombardments occurs in various applications including fabrication of cubic\nboron nitride and erosion of Hall thruster channel walls. At low ion energies,\naccurate experimental characterization of sputter yields increases in\ndifficulty due to the low yields involved. A molecular dynamics model is\nemployed to simulate the sputtering process and to calculate sputter yields for\nion energies ranging from 10 eV to 350 eV. The results are compared to\nexperimental data and a semi-empirical expression developed by Bohdansky is\nfound to adequately describe the simulation data. Surface temperature effects\nare also investigated, and the sputter yield at 850 K is approximately twice\nthat at 423 K.",
        "positive": "Quantum Dynamics of a Hydrogen Molecule Confined in a Cylindrical\n  Potential: We study the coupled rotation-vibration levels of a hydrogen molecule in a\nconfining potential with cylindrical symmetry. We include the coupling between\nrotations and translations and show how this interaction is essential to obtain\nthe correct degeneracies of the energy level scheme. We applied our formalism\nto study the dynamics of H$_{2}$ molecules inside a \"smooth\" carbon nanotube as\na function of tube radius. The results are obtained both by numerical solution\nof the ($2J+1$)-component radial Schrodinger equation and by developing an\neffective Hamiltonian to describe the splitting of a manifold of states of\nfixed angular momentum $J$ and number of phonons, $N$. For nanotube radius\nsmaller than $\\approx 3.5$ \\AA, the confining potential has a parabolic shape\nand the results can be understood in terms of a simple toy model. For larger\nradius, the potential has the \"Mexican hat\" shape and therefore the H$_{2}$\nmolecule is off-centered, yielding radial and tangential translational dynamics\nin addition to rotational dynamics of H$_{2}$ molecule which we also describe\nby a simple model. Finally, we make several predictions for the the neutron\nscattering observation of various transitions between these levels."
    },
    {
        "anchor": "Realistic simulation of reflection high-energy electron diffraction\n  patterns for two-dimensional lattices using Ewald construction: Reflection high-energy electron diffraction (RHEED) is a powerful tool for\ncharacterizing crystal surface structures. However, the setup geometry leads to\ndistorted and complicated patterns, which are not straightforward to link to\nthe real-space structures. A program with a graphical user interface is\nprovided here to simulate the RHEED patterns. Following the Ewald construction\nin the kinematic theory, we find out the exact geometric transformation in this\nmodel that determines the positions of diffraction spots. The program can deal\nwith many forms of surface structures, including surface reconstructions or\ndomains. The simulations exhibit great agreement with the experimental results\nin various cases. This program will benefit the structure analysis in thin film\ngrowth and surface science studies.",
        "positive": "Biased bilayer graphene: semiconductor with a gap tunable by electric\n  field effect: We demonstrate that the electronic gap of a graphene bilayer can be\ncontrolled externally by applying a gate bias. From the magneto-transport data\n(Shubnikov-de Haas measurements of the cyclotron mass), and using a tight\nbinding model, we extract the value of the gap as a function of the electronic\ndensity. We show that the gap can be changed from zero to mid-infrared energies\nto a value as large as 0.3 eV by using fields of < 1 V/nm, below the electric\nbreakdown of SiO2. The opening of a gap is clearly seen in the quantum Hall\nregime."
    },
    {
        "anchor": "Non-perturbative Green's function method to determine the electronic\n  spectral function due to electron-phonon interactions: Application to a\n  graphene model from weak to strong coupling: In solid state physics, the electron-phonon interaction (EPI) is central to\nmany phenomena. The theory of the renormalization of electronic properties due\nto EPIs became well established with the theory of Allen-Heine-Cardona, usually\napplied to second order in perturbation theory (P2). However, this is only\nvalid in the weak coupling regime, while strong EPIs have been reported in many\nmaterials. Although non-perturbative (NP) methods have started to arise in the\nlast years, they are usually not well justified, and it is not clear to what\ndegree they reproduce the exact theory. To address this issue, we present a\nstochastic approach for the evaluation of the non-perturbative interacting\nGreen's function in the adiabatic limit, and show it is equivalent to the\nFeynman expansion to all orders in the perturbation. Also, by defining a\nself-energy, we can reduce the effect of broadening needed in numerical\ncalculations, improving convergence in the supercell size. In addition, we\nclarify whether it is better to average the Green's function or self-energy.\nThen we apply the method to a graphene tight-binding model, and obtain several\ninteresting results: (i) The Debye-Waller term, which is normally neglected,\ndoes affect the change of the Fermi velocity. (ii) The P2 and NP self-energies\ndiffer even at room temperature for some k-points, raising the question of how\nwell P2 works in other materials. (iii) Close to the Dirac point, positive and\nnegative energy peaks merge. (iv) In the strong coupling regime, a peak appears\nat energy E=0, which is consistent with previous works on disorder and\nlocalization in graphene. (v) The spectral function becomes more asymmetric at\nstronger coupling and higher temperatures. Finally, in the Appendix we show\nthat the method has better convergent properties when the coupling is strong\nrelative to when it is weak, and discuss other technical aspects.",
        "positive": "Evolution of Ge wetting layers growing on smooth and rough Si (001)\n  surfaces: isolated {105} facets as a kinetic factor of stress relaxation: The results of STM and RHEED studies of a thin Ge film grown on the\nSi/Si(001) epitaxial layers with different surface relief are presented.\nProcess of the partial stress relaxation was accompanied by changes in the\nsurface structure of the Ge wetting layer. Besides the well-known sequence of\nsurface reconstructions ($2 \\times 1 \\rightarrow 2 \\times N \\rightarrow M\n\\times N$ patches) and hut clusters faceted with {105} planes, the formation of\nisolated {105} planes, which faceted the edges of $M \\times N$ patches, has\nbeen observed owing to the deposition of Ge on a rough Si/Si (001) surface. A\nmodel of the isolated {105} facet formation has been proposed based on the\nassumption that the mutual arrangement of the monoatomic steps on the initial\nSi surface promotes the wetting layer formation with the inhomogeneously\ndistributed thickness that results in the appearance of $M \\times N$ patches\npartially surrounded by deeper trenches than those observed in the usual Ge\nwetting layer grown on the smooth Si(001) surface. Isolated {105} facets are an\ninherent part of the Ge wetting layer structure and their formation decreases\nthe surface energy of the Ge wetting layer."
    },
    {
        "anchor": "Toward a Comprehensive Model of Snow Crystal Growth: 7. Ice Attachment\n  Kinetics near -2 C: I examine a variety snow crystal growth experiments performed at temperatures\nnear -2 C, as a function of supersaturation, background gas pressure, and\ncrystal morphology. Although the different experimental data were obtained\nusing quite diverse experimental techniques, the resulting measurements can all\nbe reasonably understood using a single comprehensive physical model for the\nbasal and prism attachment kinetics, together with particle diffusion of water\nvapor through the surrounding medium and other well-understood physical\nprocesses. As with the previous paper in this series, comparing and reconciling\ndifferent data sets at a single temperature yields significant insights into\nthe underlying physical processes that govern snow crystal growth dynamics.",
        "positive": "Topological Crystalline Transition Metals: Strained W, Ta, Mo, and Nb: In a joint theoretical and experimental investigation we show that a series\nof transition metals with strained body-centered cubic lattice ---W, Ta, Nb,\nand Mo--- host surface states that are topologically protected by mirror\nsymmetry. Our finding extends the class of topologically nontrivial systems by\ntopological crystalline transition metals. The investigation is based on\nindependent calculations of the electronic structures and of topological\ninvariants, the results of which agree with established properties of the\nDirac-type surface state in W(110). To further support our prediction, we\ninvestigate both experimentally by spin-resolved inverse photoemission and\ntheoretically an unoccupied topologically nontrivial surface state in Ta(110)."
    },
    {
        "anchor": "Construction of $A$-$B$ hetero-layer intermetallic crystals: case\n  studies of the 1144-phase TM-phosphides \\textit{AB}(TM)$_4$P$_4$ (TM=Fe, Ru,\n  Co, Ni: The discovery of the 1144-phase, e.g. CaKFe$_4$As$_4$, creates opportunities\nto build novel intermetallics with alternative stacking of two parent\ncompounds. Here we formalize the idea by defining a class of bulk crystalline\nsolids with $A$-$B$ stacking (including 1144-phases and beyond), which is a\ngeneralization of hetero-structures from few-layer or thin-film semi-conductors\nto bulk intermetallics. Theoretically, four families of phosphides\n\\textit{AB}(TM)$_4$P$_4$ (TM=Fe, Ru, Co, Ni) are investigated by\nfirst-principles calculations, wherein configurational, vibrational and\nelectronic degrees of freedom are considered. It predicts a variety of stable\n1144-phases (especially Ru- and Fe-phosphides). Stability rules are found and\nstructural/electronic properties are discussed. Experimentally, we synthesize\nhigh-purity CaKRu$_4$P$_4$ as a proof of principle example. The synthetic\nmethod is simple and easily applied. Moreover, it alludes to a strategy to\nexplore complex multi-component compounds, facilitated by a phase diagram\ncoordinated by collective descriptors.",
        "positive": "Aluminum oxide n Si field effect inversion layer solar cells with\n  organic top contact: We demonstrate a novel type of solar cell, one that uses fixed negative\ncharges, formed at the interface of n-Si with Al2O3, to generate strong\ninversion at the Si surface by electrostatic repulsion. Built-in voltages of up\nto 755 mV are found at this interface. To be able to harness this large\nbuilt-in voltage, we demonstrate a new photovoltaic device concept, where the\nphotocurrent, generated in this inversion layer, is extracted via an inversion\nlayer induced by a high work function PEDOT:PSS top contact, deposited on top\nof a passivating and dipole-inducing molecular monolayer. Results of the effect\nof the molecular monolayer on device performance yield open-circuit voltages of\nup to 550 mV for moderately doped Si, demonstrating the effectiveness of this\ncontact structure in removing the Fermi level pinning that has hindered past\nefforts in developing this type of solar cell with n-type Si."
    },
    {
        "anchor": "Impacts of Doping on Epitaxial Germanium Thin Film Quality and Si-Ge\n  Interdiffusion: Ge-on-Si structures with three different dopants (P, As and B) and those\nwithout intentional doping were grown and annealed. Several different materials\ncharacterization methods have been performed to characterize the Ge film\nquality. All samples have a smooth surface (roughness < 1.5 nm), and the Ge\nfilms are almost entirely relaxed. On the other hand, B doped Ge films have\nthreading dislocations above 1 x 10^8 cm-2. While P and As doping can reduce\nthe threading dislocation density to be less than 10^6 cm-2 without annealing.\nThe interdiffusion of Si and Ge of different films have been investigated\nexperimentally and theoretically. A quantitative model of Si-Ge interdiffusion\nunder extrinsic conditions across the full x_Ge range and with the dislocation\nmediated diffusion term was established. The Kirkendall effect has been\nobserved. The results are of technical significance for the structure, doping,\nand process design of Ge-on-Si based devices, especially for photonic\napplications.",
        "positive": "Effect of doping on performance of organic solar cells: Conventional models of planar and bulk heterojunction organic solar cells\nhave been extended by introducing doping in the active layer. We have studied\nthe performance of organic solar cells as a function of dopant concentration.\nFor bulk heterojunction cells, the modeling shows that for the most studied\nmaterial pair (poly-3-hexylthiophene, P3HT, and phenyl-C61-butyric acid methyl\nester, PCBM) doping decreases the short-circuit current density (JSC), fill\nfactor (FF) and efficiency. However, if bulk heterojunction cells are not\noptimized, namely, at low charge carrier mobilities, unbalanced mobilities or\nnon-ohmic contacts, the efficiency can be increased by doping. For planar\nheterojunction cells, the modeling shows that if the acceptor layer is n doped,\nand the donor layer is p doped, the open-circuit voltage, JSC, FF and hence the\nefficiency can be increased by doping. Inversely, when the acceptor is p doped,\nand the donor is n doped; FF decreases rapidly with increasing dopant\nconcentrations so that the current-voltage curve becomes S shaped. We also show\nthat the detrimental effect of nonohmic contacts on the performance of the\nplanar heterojunction cell can be strongly weakened by doping."
    },
    {
        "anchor": "Molecular Dynamics Study of Stiffness in Polystyrene and Polyethylene: In this paper, we have studied polystyrene (PS) and polyethylene (PE)\nstiffness by 3-dimensional Langevin Molecular Dynamics simulation. Hard\npolymers have a very small bending, and thus, their end-to-end distance is more\nthan soft polymers. Quantum dot lasers can be established as colloidal\nparticles dipped in a liquid and grafted by polymer brushes to maintain the\nsolution. Here by a study on molecular structures of PS and PE, we show that\nthe principle reason lies on large phenyl groups around the backbone carbons of\nPS, rather than a PE with Hydrogen atoms. Our results show that the mean radius\nof PS random coil is more than PE which directly affects the quantum dot\nmaintenance. In addition, effect of temperature increase on the mean radius is\ninvestigated. Our results show that by increasing temperature, both polymers\ntend to lengthen, and at all temperatures a more radius is predicted for PS\nrather than PE, but interestingly, with a difference in short and long chains.\nWe show that stiffness enhancement is not the same at short and long polymers\nand the behavior is very different. Our results show a good consonance with\nboth experimental and theoretical studies.",
        "positive": "BP_5 Monolayer with Multiferroicity and Negative Poisson's Ratio: A\n  Prediction by Global Optimization Method: Based on variable components global optimization algorithm, we predict a\nstable two-dimensional (2D) phase of boron phosphide with 1:5 stoichiometry,\ni.e. boron pentaphosphide (BP_5) monolayer, which has a lower formation energy\nthan that of the commonly believed graphitic phase (g-BP). BP_5 monolayer is a\nmultiferroic material with coupled ferroelasticity and ferroelectricity. The\npredicted reversible strain is up to 41.41%, which is the largest among all\nreported ferroelastic materials. Due to the non-centrosymmetric structure and\nelectronegativity differences between boron and phosphorus atoms, an in-plane\nspontaneous polarization of 326.0 pC/m occurs in BP_5. Moreover, the recently\nhunted negative Poisson's ratio property, is also observed in BP_5. As an\nindirect semiconductor with a band gap of 1.34 eV, BP_5 displays outstanding\noptical and electronic properties, for instance strongly anisotropic\nvisible-light absorption and high carrier mobility. The rich and extraordinary\nproperties of BP_5 make it a potential nanomaterial for designing\nelectromechanical or optoelectronic devices, such as nonvolatile memory with\nconveniently readable/writeable capability. Finally, we demonstrate that AlN\n(010) surface could be a suitable substrate for epitaxy growth of BP_5\nmonolayer."
    },
    {
        "anchor": "A first principles study of sub-monolayer Ge on Si(001): Experimental observations of heteroepitaxial growth of Ge on Si(001) show a\n(2xn) reconstruction for sub-monolayer coverages, with dimer rows crossed by\nmissing-dimer trenches. We present first-principles density-functional\ncalculations designed to elucidate the energetics and relaxed geometries\nassociated with this reconstruction. We also address the problem of how the\nformation energies of reconstructions having different stoichiometries should\nbe compared. The calculations reveal a strong dependence of the formation\nenergy of the missing-dimer trenches on spacing n, and demonstrate that this\ndependence stems almost entirely from elastic relaxation. The results provide a\nnatural explanation for the experimentally observed spacings in the region of n\n\\~ 8.",
        "positive": "Effect of Scattering Efficiency in the Tip Enhanced Raman Spectroscopic\n  Imaging of Nanostructures in the Sub Diffraction Limit: The experimental limitations in the signal enhancement and spatial resolution\nin spectroscopic imaging have been always a challenging task in the application\nof near-field spectroscopy for nanostructured materials in the sub-diffraction\nlimit. In addition, the scattering efficiency also plays an important role in\nimproving signal enhancement and contrast of the spectroscopic imaging of\nnanostructures by scattering of light. We report the effect of scattering\nefficiency in the Raman intensity enhancement, and contrast generation in\nnear-field tip-enhanced Raman spectroscopic (TERS) imaging of one dimensional\ninorganic crystalline nanostructures of Si and AlN having a large variation in\npolarizability change. The Raman enhancement of pure covalently bonded Si\nnanowire (NW) is found to be two orders of higher in magnitude for the TERS\nimaging, as compared to that of AlN nanotip (NT) having a higher degree of\nionic bonding, suggesting the importance of scattering efficiency of the\nmaterials in TERS imaging. The strong contrast generation due to higher signal\nenhancement in TERS imaging of Si NW also helped in achieving the better\nresolved spectroscopic images than that of the AlN NT. The study provides an\ninsight into the role of scattering efficiency in the resolution of near-field\nspectroscopic images."
    },
    {
        "anchor": "An effective magnetic field from optically driven phonons: Light fields at THz and mid-infrared frequencies allow for the direct\nexcitation of collective modes in condensed matter, which can be driven to\nlarge amplitudes. For example, excitation of the crystal lattice, has been\nshown to stimulate insulator-metal transitions, melt magnetic order, or enhance\nsuperconductivity. Here, we generalize these ideas and explore the simultaneous\nexcitation of more than one lattice mode, which are driven with controlled\nrelative phases. This nonlinear mode mixing drives rotations as well as\ndisplacements of the crystal-field atoms, mimicking the application of a\nmagnetic field and resulting in the excitation of spin precession in the\nrare-earth orthoferrite $ErFeO_3$. Coherent control of lattice rotations may\nbecome applicable to other interesting problems in materials research, for\nexample as a way to affect the topology of electronic phases.",
        "positive": "Prediction of three-fold fermions in a nearly-ideal Dirac semimetal\n  BaAgAs: Materials with triply-degenerate nodal points in their low-energy electronic\nspectrum produce crystalline-symmetry-enforced three-fold fermions, which\nconceptually lie between the two-fold Weyl and four-fold Dirac fermions. Here\nwe show how a silver-based Dirac semimetal BaAgAs realizes three-fold fermions\nthrough our first-principles calculations combined with a low-energy effective\n$\\mathbf{k.p}$ model Hamiltonian analysis. BaAgAs is shown to harbor\ntriply-degenerate nodal points, which lie on its $C_{3}$ rotation axis, and are\nprotected by the $C_{6v}$($C_2\\otimes C_{3v}$) point-group symmetry in the\nabsence of spin-orbit coupling (SOC) effects. When the SOC is turned on, BaAgAs\ntransitions into a nearly-ideal Dirac semimetal state with a pair of Dirac\nnodes lying on the $C_{3}$ rotation axis. We show that breaking inversion\nsymmetry in the BaAgAs$_{1-x}$P$_x$ alloy yields a clean and tunable three-fold\nfermion semimetal. Systematic relaxation of other symmetries in BaAgAs\ngenerates a series of other topological phases. BaAgAs materials thus provide\nan ideal platform for exploring tunable topological properties associated with\na variety of different fermionic excitations."
    },
    {
        "anchor": "Strain-gradient-induced switching of nanoscale domains in free-standing\n  ultrathin films: We report first-principle atomistic simulations on the effect of local strain\ngradients on the nanoscale domain morphology of free-standing PbTiO$_3$\nultrathin films. First, the ferroelectric properties of free films at the\natomic level are reviewed. For the explored thicknesses (10 to 23 unit cells),\nwe find flux-closure domain structures whose morphology is thickness dependent.\nA critical value of 20 unit cells is observed: thinner films show structures\nwith 90$^\\circ$ domain loops, whereas thicker ones develop, in addition,\n180$^\\circ$ domain walls, giving rise to structures of the Landau-Lifshitz\ntype. When a local and compressive strain gradient at the top surface is\nimposed, the gradient is able to switch the polarization of the downward\ndomains, but not to the opposite ones. The evolution of the domain pattern as a\nfunction of the strain gradient strength consequently depends on the film\nthickness. Our simulations indicate that in thinner films, first the 90$^\\circ$\ndomain loops migrate towards the strain-gradient region, and then the\npolarization in that zone is gradually switched. In thicker films, instead, the\nswitching in the strain-gradient region is progressive, not involving\ndomain-wall motion, which is attributed to less mobile 180$^\\circ$ domain\nwalls. The ferroelectric switching is understood based on the knowledge of the\nlocal atomic properties, and the results confirm that mechanical\nflexoelectricity provides a means to control the nanodomain pattern in\nferroelectric systems.",
        "positive": "Non-intrinsic superconductivity in InN epilayers: role of Indium Oxide: In recent years there have been reports of anomalous electrical resistivity\nand the presence of superconductivity in semiconducting InN layers. By a\ncareful correlation of the temperature dependence of resistivity and magnetic\nsusceptibility with structural information from highresolution x-ray\ndiffraction measurements we show that superconductivity is not intrinsic to InN\nand is seen only in samples that show traces of oxygen impurity. We hence\nbelieve that InN is not intrinsically a superconducting semiconductor."
    },
    {
        "anchor": "Enhancement of Two photon absorption with Ni doping in the dilute\n  magnetic Semiconductor ZnO Crystalline Nanorods: In this letter, we have investigated the third-order optical nonlinearities\nof high-quality Ni doped ZnO nanorods crystallized in wurtzite lattice,\nprepared by the wet chemical method. In our experiments, we found that the two\nphoton absorption coefficient beta increases by as much as 14 times i.e. 7.6\nerr 0.4 to 112 err 6 cm per GW, when the Ni doping is increased from 0 to 10\npercent. The substantial enhancement in beta is discussed in terms of the\nbandgap scaling and Ni doping. Furthermore, we also show that the optical\nbandgap measured by UVVis and photo luminescence spectroscopic, continuously\nred shift with increasing Ni doping concentration. We envision that the strong\nnonlinear optical properties together with their dilute magnetic effects, they\nform an important class of materials for potential applications in\nmagneto-optical and integrated optical chips.",
        "positive": "Novel rhenium carbides at 200 GPa: Laser heating of rhenium in a diamond anvil cell to 3000 K at about 200 GPa\nresults in formation of two previously unknown rhenium carbides, hexagonal\nWC-type structured ReC and orthorhombic TiSi2-type structured ReC2. The Re-C\nslid solution formed at multimegabar pressure has the carbon content of ca. 20\nat%. Unexpectedly long C-C distances (ca. 1.76-1.85 A) in 'graphene-like'\ncarbon nets in the structure of ReC2 cannot be explained by a simple covalent\nbonding between carbon atoms and suggest that at very high pressures the\nmechanism of interaction between carbon atoms in inorganic compounds may be\ndifferent from that considered so far."
    },
    {
        "anchor": "Performance Enhancement of Black Phosphorus Field-Effect Transistors by\n  Chemical Doping: In this letter, a new approach to chemically dope black phosphorus (BP) is\npresented, which significantly enhances the device performance of BP\nfield-effect transistors for an initial period of 18 h, before degrading to\npreviously reported levels. By applying\n2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), low ON-state\nresistance of 3.2 ohm.mm and high field-effect mobility of 229 cm2/Vs are\nachieved with a record high drain current of 532 mA/mm at a moderate channel\nlength of 1.5 {\\mu}m.",
        "positive": "Emergence of Griffiths phase, re-entrant cluster glass,metamagnetic\n  transition and field induced unusual spin dynamics in Tb2CoMnO6: The structural and magnetic properties of double perovskiteTb2CoMnO6 have\nbeen investigated. Electronic structure analysis by XPS study reveals the\npresence of mixed oxidation state (Mn4+/Mn3+ and Co2+/Co3+) of B-site ions. The\ndc and ac magnetization measurements reveal different interesting phases such\nas Griffith phase, re-entrant spin glass, metamagnetic steps, Hopkinson like\npeak and also unusual slow relaxation. The M-H curve indicates the presence of\ncompeting AFM/FM interactions. The disorder in Tb2CoMnO6 leads to spin\nfrustration at low temperature giving rise to the re-entrant spin glass.\nMoreover, the field-dependent ac susceptibility studies unraveled the presence\nof Hopkinson like peak associated with the domain wall motion and the large\nanisotropy field. The further study yielded that the relaxation associated with\nthis peak is unusually slow."
    },
    {
        "anchor": "Role of polar compensation in interfacial ferromagnetism of\n  LaNiO$_3$/CaMnO$_3$ superlattices: Polar compensation can play an important role in the determination of\ninterfacial electronic and magnetic properties in oxide heterostructures. Using\nx-ray absorption spectroscopy, x-ray magnetic circular dichroism, bulk\nmagnetometry, and transport measurements, we find that interfacial charge\nredistribution via polar compensation is essential for explaining the evolution\nof interfacial ferromagnetism in LaNiO$_3$/CaMnO$_3$ superlattices as a\nfunction of LaNiO$_3$ layer thickness. In insulating superlattices (4 unit\ncells or less of LaNiO$_3$), magnetism is dominated by Ni-Mn superexchange,\nwhile itinerant electron-based Mn-Mn double-exchange plays a role in thicker\nmetallic superlattices. X-ray magnetic circular dichroism and resonant x-ray\nscattering show that Ni-Mn superexchange contributes to the magnetization even\nin metallic superlattices. This Ni-Mn superexchange interaction can be\nexplained in terms of polar compensation at the LaNiO$_3$-CaMnO$_3$ interface.\nThese results highlight the different mechanisms responsible for interfacial\nferromagnetism and the importance of understanding compensation due to polar\nmismatch at oxide-based interfaces when engineering magnetic properties.",
        "positive": "Towards a bulk theory of flexoelectricity: Flexoelectricity is the linear response of polarization to a strain gradient.\nHere we address the simplest class of dielectrics, namely elemental cubic\ncrystals, and we prove that therein there is no extrinsic (i.e. surface)\ncontribution to flexoelectricity in the thermodynamic limit. The flexoelectric\ntensor is expressed as a bulk response of the solid, manifestly independent of\nsurface configurations. Furthermore, we prove that the flexoelectric responses\ninduced by a long-wavelength phonon and by a uniform strain gradient are\nidentical."
    },
    {
        "anchor": "High-performance near- and mid-infrared crystalline coatings: Substrate-transferred crystalline coatings have recently emerged as a\ngroundbreaking new concept in optical interference coatings. Building upon our\ninitial demonstration of this technology, we have now realized significant\nimprovements in the limiting optical performance of these novel single-crystal\n$GaAs/Al_{x}Ga_{1-x}As$ multilayers. In the near-infrared (NIR), for coating\ncenter wavelengths spanning 1064 to 1560 nm, we have reduced the excess optical\nlosses (scatter + absorption) to levels as low as 3 parts per million, enabling\nthe realization of a cavity finesse exceeding $3\\times 10^{5}$ at the\ntelecom-relevant wavelength range near 1550 nm. Moreover, we demonstrate the\ndirect measurement of sub-ppm optical absorption at 1064 nm. Concurrently, we\ninvestigate the mid-IR (MIR) properties of these coatings and observe\nexceptional performance for first attempts in this important wavelength region.\nSpecifically, we verify excess losses at the hundred ppm level for wavelengths\nof 3300 and 3700 nm. Taken together, our NIR optical losses are now fully\ncompetitive with ion beam sputtered multilayer coatings, while our first\nprototype MIR optics have already reached state-of-the-art performance levels\nfor reflectors covering this portion of the fingerprint region for optical gas\nsensing. Mirrors fabricated with our crystalline coating technique exhibit the\nlowest mechanical loss, and thus the lowest Brownian noise, the highest thermal\nconductivity, and, potentially, the widest spectral coverage of any\n\"supermirror\" technology in a single material platform. Looking ahead, we see a\nbright future for crystalline coatings in applications requiring the ultimate\nlevels of optical, thermal, and optomechanical performance",
        "positive": "Thermoelectric properties of high-entropy rare-earth cobaltates: High-entropy concept introduced with a promising paradigm to obtain exotic\nphysical properties has motivated us to explore the thermoelectric properties\nof Sr-substituted high-entropy rare-earth cobaltates i.e.,\n(LaNdPrSmEu)$_{1-x}$Sr$_x$CoO3 (0 \\leq x \\leq 0.10). The structural analysis of\nthe samples synthesized using the standard solid-state route, confirms the\northorhombic structure with the Pbnm space group. The Seebeck coefficient and\nelectrical resistivity decrease with rising Sr concentration as well as with an\nincrease in temperature. The multiple A-site ions in high-entropy rare-earth\ncobaltates result in an improved Seebeck coefficient ({\\alpha}) compared to\nLa$_{0.95}$Sr$_{0.05}$CoO$_3$, associated with a decrease in the Co-O-Co bond\nangle, which further enhances the power factor. The random distribution of\ncations at the rare-earth site results in a significant lowering of phonon\nthermal conductivity. As a result, a maximum figure of merit (zT) of 0.23 is\nobtained at 350K for (LaNdPrSmEu)$_{0.95}$Sr$_{0.05}$CoO$_3$, which is one of\nthe highest values of zT reported at this temperature for oxide materials. This\nstudy shows promise to decouple thermoelectric parameters using the\nhigh-entropy concept in several materials."
    },
    {
        "anchor": "Anisotropic Dzyaloshinskii-Moriya interaction and topological magnetism\n  in two-dimensional magnets protected by P4-m2 crystal symmetry: As a fundamental magnetic parameter, Dzyaloshinskii-Moriya interaction (DMI),\nhas gained a great deal of attention in the last two decades due to its\ncritical role in formation of magnetic skyrmions. Recent discoveries of\ntwo-dimensional (2D) van der Waals (vdW) magnets has also gained a great deal\nof attention due to appealing physical properties, such as gate tunability,\nflexibility and miniaturization. Intensive studies have shown that isotropic\nDMI stabilizes ferromagnetic (FM) topological spin textures in 2D magnets or\ntheir corresponding heterostructures. However, the investigation of anisotropic\nDMI and antiferromagnetic (AFM) topological spin configurations remains\nelusive. Here, we propose and demonstrate that a family of 2D magnets with\nP4-m2 symmetry-protected anisotropic DMI. More interestingly, various\ntopological spin configurations, including FM/AFM antiskyrmion and AFM\nvortex-antivortex pair, emerge in this family. These results give a general\nmethod to design anisotropic DMI and pave the way towards topological magnetism\nin 2D materials using crystal symmetry.",
        "positive": "Epitaxial growth and magnetic characterization of EuSe thin films with\n  various crystalline orientations: We report different growth modes and corresponding magnetic properties of\nthin EuSe films grown by molecular beam epitaxy on BaF2, Pb1-xEuxSe, GaAs, and\nBi2Se3 substrates. We show that EuSe growth predominantly in (001) orientation\non GaAs(111) and Bi2Se3, but along (111) crystallographic direction on BaF2\n(111) and Pb1-xEuxSe (111). High-resolution transmission electron microscopy\nmeasurements reveal an abrupt and highly crystalline interface for both (001)\nand (111) EuSe films. In agreement with previous studies, ordered magnetic\nphases include antiferromagnetic, ferrimagnetic, and ferromagnetic phases. In\ncontrast to previous studies, we found strong hysteresis for the\nantiferromagnetic-ferrimagnetic transition. An ability to grow epitaxial films\nof EuSe on Bi2Se3 and of Bi2Se3 on EuSe enables further investigation of\ninterfacial exchange interactions between various phases of an insulating\nmetamagnetic material and a topological insulator."
    },
    {
        "anchor": "Charge transfer tuning in TiO2 hybrid nanostructures with\n  acceptor-acceptor systems: An interesting interplay between two different modifiers and the surface of\ntitanium dioxide leads to a significant change in photoelectrochemical\nproperties of the designed hybrid materials. The semiconductor is\nphotosensitized by one of the counterparts and exhibits the\nphotoelectrochemical photocurrent switching effect thanks to interactions with\ngraphene oxide - the second modifier mediates charge transfer processes in the\nsystem, allowing us to design the materials response at the molecular level.\nBased on the selection of molecular counterpart we may affect the behaviour of\nhybrids upon light irradiation in a different manner, which may be useful for\nthe applications in photovoltaics, optoelectronics and photocatalysis. Here we\nfocus particularly on the nanocomposites made of titanium dioxide with graphene\noxide combined with either 2,3,5,6-tetrachlorobenzoquinone or\n2,3-dichloro-5,6-dihydroxybenzoquinone - for these two materials we observed a\nmajor change in the charge transfer processes occurring in the system.",
        "positive": "The role of zero-point effects in catalytic reactions involving hydrogen: According to the Heisenberg uncertainty principle of quantum mechanics,\nparticles which are localized in space by a bounding potential must have a\nfinite distribution of momenta. This leads, even in the lowest-possible energy\nstate, to vibrations, and thus, to the so-called zero-point energy. For\nchemically bound hydrogen the zero-point energy can be quite substantial. For\nexample, for a free H_2 molecule it is 0.26 eV, a significant value in the\nrealm of chemistry, where often an energy of the order of 0.1 eV/atom (or 2.3\nkcal/mol) decides whether or not a chemical reaction takes place with an\nappreciable rate. Yet, in many theoretical studies the dynamics of chemical\nreactions involving hydrogen has been treated classically or quasi-classically,\nassuming that the quantum mechanical nature of H nuclei, i.e. the zero-point\neffects, will not strongly affect the relevant physical or chemical properties.\nIn this paper we show that this assumption is not justified. We will\ndemonstrate that for very basic and fundamental catalytic-reaction steps,\nnamely the dissociative adsorption of molecular hydrogen at transition metal\nsurfaces and its time-reverse process, the associative desorption, zero-point\neffects can not only quantitatively but even qualitatively affect the chemical\nprocesses and rates. Our calculations (treating electrons as well as H nuclei\nquantum-mechanically) establish the importance of additional zero-point effects\ngenerated by the H_2-surface interaction and how energy of the H-H stretch\nvibration is transferred into those and vice versa."
    },
    {
        "anchor": "Elastic Constant Measurement from Vibrational Mode Frequencies in\n  Resonant Ultrasound Spectroscopy: Execution of Resonant Ultrasound Spectroscopy (RUS) for accurate measurement\nof elastic constants lies primarily on a perfect matching in the calculated and\nmeasured mode frequencies of free vibration. Calculation of these frequencies\nrequire estimated values of the elastic constants of the material under study,\nand one has to depend on other experiments for these data. The present work\nproposes and demonstrates an alternative to derive initial guess values of\nessential parameters for an isotropic and homogeneous material from the\nacquired RUS spectra itself. Specimen samples are taken in the shape of\nrectangular parallelepiped having nearly same cross-sectional dimension but\nwith different lengths. For particular compressional (shear) mode corresponding\nto length l, the frequency fis inversely proportional to l. The slope m of f\nversus 1/l plot equals to half of the compressional (shear) velocity and this\nin turn gives an estimate of c_11 (c_44). With these parameters as the input\nguess parameters, RUS fitting method is executed to find out the best fit\nresults. Elastic constants of commercially available specimens of aluminium,\ncopper, lead, steel and brass are measured in this technique assuming\nmacroscopic homogeneity. Results show good agreement with available literature\nvalues.",
        "positive": "Emergent grain boundary phases in stressed polycrystalline thin films: The grain boundary (GB) microstructure influences and is influenced by the\ndevelopment of residual stresses during synthesis of polycrystalline thin\nfilms. Recent studies have shown that the frustration between the preferred\ngrowth direction and rotations of abutting crystals to local cusps in GB\nenergies leads to internal stresses localized within nanoscopic surface layers\naround the valleys and ridges that form at emergent boundaries (eGBs). Using a\ncombination of continuum frameworks, numerical analyses and all-atom\nsimulations of bicrystal $\\langle 111\\rangle$ copper films, we show that eGBs\ntune their surface morphology and rotation extent in response to external\nstrains. Compression favors rotation to and growth of low energy GB phases\n(complexions) at eGB valleys while tension favors the transitions at eGB\nridges, a reflection of the stress-induced mass efflux/influx that changes the\nenergetic balance between interfacial and deformation energies. Molecular\ndynamics simulations of strained and growing bicrystal films reveal that the\neGB phase transition is coupled to island formation at the surface triple\njunctions, providing a direct link between eGB phases and surface step flow.\nThe interplay between eGB structure, morphology and mechanics emerges as a\ncrucial ingredient for predictive understanding of stress and morphological\nevolution during film growth, with broad implications for multifunctional\nresponse of polycrystalline surfaces in a diverse range of surface phenomena\nsuch as surface mediated deformation, interfacial embrittlement, thermal\ngrooving, stress corrosion, surface catalysis and topological conduction."
    },
    {
        "anchor": "Path to finding the critical thickness for memory in thin ferroelectric\n  films: The finite screening length by real metallic electrodes, albeit very small\n(<1A), results in finite depolarizing field that tends to split the film into\ndomains. In very thin ferroelectric films the domain structure reduces to\nsinusoidal distribution of polarization considered first in the 1980s. We\ndiscuss the phase transition between this structure and a single domain state\nand show that it is first order, if it exists at all. The alternative\npossibility is that the single domain state at zero bias voltage would be\nmetastable for all temperatures in most systems. This scenario defines a path\ntowards solution to a problem of finding parameters of a system that can\nsustain the ferroelectric memory over a desired period of time.",
        "positive": "Electronic structure of porphyrin-based metal-organic frameworks and\n  their suitability for solar fuel production photocatalysis: Metal-organic frameworks (MOFs) can be exceptionally good catalytic materials\nthanks to the presence of active metal centres and a porous structure that is\nadvantageous for molecular adsorption and confinement. We present here a\nfirst-principles investigation of the electronic structure of a family of MOFs\nbased on porphyrins connected through phenyl-carboxyl ligands and AlOH species,\nin order to assess their suitability for the photocatalysis of fuel production\nreactions using sunlight."
    },
    {
        "anchor": "Valley-polarized quantum anomalous Hall insulator in monolayer\n  $\\mathrm{RuBr_2}$: Coexistence of intrinsic ferrovalley (FV) and nontrivial band topology\nattracts intensive interest both for its fundamental physics and for its\npotential applications, namely valley-polarized quantum anomalous Hall\ninsulator (VQAHI). Here, based on first-principles calculations by using\ngeneralized gradient approximation plus $U$ (GGA+$U$) approach, the VQAHI\ninduced by electronic correlation or strain can occur in monolayer\n$\\mathrm{RuBr_2}$. For perpendicular magnetic anisotropy (PMA), the ferrovalley\n(FV) to half-valley-metal (HVM) to quantum anomalous Hall (QAH) to HVM to FV\ntransitions can be driven by increasing electron correlation $U$. However,\nthere are no special QAH states and valley polarization for in-plane magnetic\nanisotropy. By calculating actual magnetic anisotropy energy (MAE), the VQAHI\nindeed can exist between two HVM states due to PMA, a unit Chern number/a\nchiral edge state and spontaneous valley polarization. The increasing $U$ can\ninduce VQAHI, which can be explained by sign-reversible Berry curvature or band\ninversion between $d_{xy}$/$d_{x^2-y^2}$ and $d_{z^2}$ orbitals. Even though\nthe real $U$ falls outside the range, the VQAHI can be achieved by strain.\nTaking $U$$=$2.25 eV as a concrete case, the monolayer $\\mathrm{RuBr_2}$ can\nchange from a common ferromagentic (FM) semiconductor to VQAHI under about\n0.985 compressive strain. It is noted that the edge states of VQAHI are\nchiral-spin-valley locking, which can achieve complete spin and valley\npolarizations for low-dissipation electronics devices. Both energy band gap and\nvalley splitting of VQAHI in monolayer $\\mathrm{RuBr_2}$ are higher than the\nthermal energy of room temperature (25 meV), which is key at room temperature\nfor device applications.",
        "positive": "Al-doped ZnO aligned nanorod arrays significant implications for optic\n  and opto-electronic Applications: We investigated the optical and optoelectronic properties of vertically\naligned Al:ZnO nanorod arrays synthesized by the hydrothermal technique at a\nconsiderably low temperature on a sputtered Al-ZnO seed layer. The nanorod\narrays maintained remarkable alignment along the c-axis over a large area. The\nseed layers and nanorod arrays showed various optical band gaps. Investigation\nof the optoelectronic properties of nanorod arrays on"
    },
    {
        "anchor": "[Ag(NH3)2]2SO4: A coordination strategy on the cationic-moiety to design\n  nonlinear optical materials: Over decades, guided by the anionic group theory, the majority work has been\nfocused on the anionic-moiety of a nonlinear optical material, however, the\nproperty guided structure modification and design on the cationic-moiety has\nlong been neglected. Herein, we report for the first time a coordination\nstrategy on the cationic-moiety, as demonstrated by the first exmple,\n[Ag(NH3)2]2SO4 vs Ag2SO4, the coordination of the plus one Ag+ cation by the\nneutral ligand forming the [Ag(NH3)2]+ cationic-moiety drives the formation of\nthe noncentrosymmetric tetragonal P-421c structure which exhibits a remarkable\nproperty improvement, including a strong SHG intersity (1.4*KDP vs 0 @1064 nm),\nand a large birefringence (delta(n)cal.: 0.102 vs 0.012 @1064 nm). Furthermore,\nwe discover that owing to the strong hydrogen bonds and spatial confinement of\n[SO4]2- anions, the cation [Ag(NH3)2]+ bends parallel to the crystallographic c\naxis with a bond angle of N-Ag-N = 174.35deg, generating a permenant dipole\nmoment z = -0.12 D that is responsible for the large birefringence that\nenlarges the range of the phase matching SHG laser output. We believe what we\ndiscover is only a glimpse of the long been neglected crystal engineering on\nthe cationic-moiety. Encourage by this work, exciting works on other ionic\ncompound systems shall flood in.",
        "positive": "Strain-adjustable reflectivity of polyurethane nanofiber membrane for\n  thermal management applications: Passive radiative cooling technologies are highly attractive in pursuing\nsustainable development. However, current cooling materials are often static,\nwhich makes it difficult to cope with the varying needs of all-weather thermal\ncomfort management. Herein, a strategy is designed to obtain flexible\nthermoplastic polyurethane nanofiber (Es-TPU) membranes via electrospinning,\nrealizing reversible in-situ solvent-free switching between radiative cooling\nand solar heating through changes in its optical reflectivity by stretching. In\nits radiative cooling state (0% strain), the Es-TPU membrane shows a high and\nangular-independent reflectance of 95.6% in the 0.25-2.5 {\\mu}m wavelength\nrange and an infrared emissivity of 93.3% in the atmospheric transparency\nwindow (8-13 {\\mu}m), reaching a temperature drop of 10 {\\deg}C at midday, with\na corresponding cooling power of 118.25 W/m2. The excellent mechanical\nproperties of the Es-TPU membrane allows the continuous adjustment of\nreflectivity by reversibly stretching it, reaching a reflectivity of 61.1%\n({\\Delta}R=34.5%) under an elongation strain of 80%, leading to a net\ntemperature increase of 9.5 {\\deg}C above ambient of an absorbing substrate and\nan equivalent power of 220.34 W/m2 in this solar heating mode. The strong haze,\nhydrophobicity and outstanding aging resistance exhibited by this scalable\nmembrane hold promise for achieving uniform illumination with tunable strength\nand efficient thermal management in practical applications."
    },
    {
        "anchor": "A tool to predict coercivity in magnetic materials: Magnetic coercivity is often viewed to be lower in alloys with negligible (or\nzero) values of the anisotropy constant. However, this explains little about\nthe dramatic drop in coercivity in FeNi alloys at a non-zero anisotropy value.\nHere, we develop a theoretical and computational tool to investigate the\nfundamental interplay between material constants that govern coercivity in bulk\nmagnetic alloys. The two distinguishing features of our coercivity tool are\nthat: (a) we introduce a large localized disturbance, such as a spike-like\nmagnetic domain, that provides a nucleation barrier for magnetization reversal;\nand (b) we account for magneto-elastic energy -- however small -- in addition\nto the anisotropy and magnetostatic energy terms. We apply this coercivity tool\nto show that the interactions between local instabilities and material\nconstants, such as anisotropy and magnetostriction constants, are key factors\nthat govern magnetic coercivity in bulk alloys. Using our model, we show that\ncoercivity is minimum at the permalloy composition (Fe-21.5Ni-78.5) at which\nthe alloy's anisotropy constant is not zero. We systematically vary the values\nof the anisotropy and magnetostriction constants, around the permalloy\ncomposition, and identify new combinations of material constants at which\ncoercivity is small. More broadly, our coercivity tool provides a theoretical\nframework to potentially discover novel magnetic materials with low coercivity.",
        "positive": "Formation and Classification of Amorphous Carbon by Molecular Dynamics\n  Simulation: By using molecular dynamics simulation, formation mechanisms of amorphous\ncarbon in particular sp${}^3$ rich structure was researched. The problem that\nreactive empirical bond order potential cannot represent amorphous carbon\nproperly was cleared in the transition process from graphite to diamond by high\npressure and the deposition process of amorphous carbon thin films. Moreover,\nthe new potential model which is based on electron distribution simplified as a\npoint charge was developed by using downfolding method. As a result, the\nmolecular dynamics simulation with the new potential could demonstrate the\ntransition from graphite to diamond at the pressure of 15 GPa corresponding to\nexperiment and the deposition of sp${}^3$ rich amorphous carbon."
    },
    {
        "anchor": "A new quantum hydrodynamic description of ferroelectricity in spiral\n  magnets: The strong coupling between magnetism and ferroelectricity was found in rare\nearth manganites, where the electric polarization could be induced by special\nmagnetic ordering. There is no theoretical model that would allow us to study\nthe static and dynamic properties of electric polarization in strongly\ncorrelated magnetic dielectrics. In the presented research, we have taken the\nmain step towards the construction of such a fundamental model, and made a\ndirect connection between the microscopic Katsura-Nagaosa-Balatsky theory and\nMostovoy's phenomenological model for magnetically induced polarization. A\nnovel description of the ferroelectricity of spin origin is proposed within the\nframework of the many-particle quantum hydrodynamics method. It is applied to\nthe study of cells of magnetic ions, where the electric dipole moment is\nproportional to the vector product of spins. Our approach is based on the\nmany-particle Pauli equation, where the influence of an external magnetic field\nis considered. We define the electric dipole moment operator of the ion cell\nand introduce the macroscopic polarization as the quantum mechanical average of\nthat operator. We formulate a model for the description of nonequilibrium\npolarization and derive a new polarization evolution equation. The polarization\nswitching in ferroelectric magnets with the spiral spin-density-wave state is\nconsidered, and we demonstrate that the proposed model yields known results and\ncan predict novel effects. The dynamic magnetoelectric effect can be\ninvestigated by employing this novel equation to study the evolution of\npolarization.",
        "positive": "Rashba-type Dzyaloshinskii-Moriya interaction, perpendicular magnetic\n  anisotropy and skyrmion states at 2D materials/Co interfaces: We report a significant Dzyaloshinskii-Moriya interaction (DMI) and\nperpendicular magnetic anisotropy (PMA) at interfaces comprising hexagonal\nboron nitride (h-BN) and Co. By comparing the behavior of these phenomena at\ngraphene/Co and h-BN/Co interfaces, it is found that the DMI in latter\nincreases as a function of Co thickness and beyond three monolayers stabilizes\nwith one order of magnitude larger values compared to those at graphene/Co,\nwhere the DMI shows opposite decreasing behavior. At the same time, the PMA for\nboth systems shows similar trends with larger values for graphene/Co and no\nsignificant variations for all thickness ranges of Co. Furthermore, using\nmicromagnetic simulations we demonstrate that such significant DMI and PMA\nvalues remaining stable over large range of Co thickness give rise to formation\nof skyrmions with small applied external fields in the range of 200-250 mT up\nto 100 K temperatures. These findings open up further possibilities towards\nintegrating two-dimensional (2D) materials in spin-orbitronics devices."
    },
    {
        "anchor": "Electronic stopping power of hydrogen in a high-k material at the\n  stopping maximum and below: Electronic energy loss of hydrogen ions in HfO2 was investigated in a wide\nenergy range in the medium and low energy ion scattering regime. Experiments by\nTime-Of-Flight Medium-Energy Ion Scattering (TOF-MEIS) with proton and deuteron\nprojectiles were performed in backscattering geometry for nm-films of HfO2 on\nSi with an ultrathin SiO2 interface layer prepared by ALD. At energies around\nthe stopping maximum excellent agreement is found with earlier results from\nBehar et al. (Phys. Rev. A 80 (2009) 062901) and theoretical predictions.\nTowards lower energies discrepancies between experiment and calculations\nincrease slightly. The low energy data exhibits excellent velocity\nproportionality and indicates the absence of clear effects due to distinct\nelectronic states. Thus, also no apparent velocity threshold can be predicted\nwithin the experiments uncertainty from the present data. The magnitude of the\nenergy loss is discussed in terms of a free-electron model and compared with\nthe expected electron densities from plasmon frequencies.",
        "positive": "GdFe$_2$ Laves phase intermetallic system under pressure: an ab-initio\n  study: Here we perform $ab-initio$ study of Curie temperature $T_C$ under\nhydrostatic pressure for intermetallic compound GdFe$_2$. To calculate $T_C$\nfor GdFe$_2$ we applied mean-field solution of the Heisenberg model for several\nmagnetic sublattices with DFT/LDA calculated values of necessary exchange\ninteraction integrals and local magnetic moments. To compare with available\nexperimental data pressure values were taken from zero up to about 70 Kbar. It\ncorresponds to 2\\% compression of the volume of the unit cell. In agreement\nwith experimental data $T_C$ grows under pressure. It was shown that Fe ions\nmagnetic sublattice alone provides only about 75\\% of the experimental Curie\ntemperature $T_C^{exp}$. Gd sublattice is found to give very weak contribution\nto the $T_C^{exp}$. Here we show that the missing 25 \\% of $T_C^{exp}$ comes\nfrom Fe-Gd exchange pairs."
    },
    {
        "anchor": "Molecular dynamics simulations of palladium cluster growth on flat and\n  rough graphite surfaces: Parallel Molecular Dynamics simulations are conducted for describing growth\non surfaces with different kind of roughness: a perfect ordered crystalline\nflat graphite surface, a disordered rough graphite surface and flat surface\nwith an ordered localized defect. It is shown that disordered rough surfaces\nresults in a first step to reduction of the sticking coefficient, increased\ncluster density, size reduction. Structure of the clusters shows the\ndisappearance of the octahedral site characteristic of compact structure.\nIsolated defect induces cluster-cluster interactions that modify growth\ncompared to perfect flat surface. Kinetic study of growth shows power law\nt&#945;z evolution for low impinging atom kinetic energy. Increasing kinetic\nenergy, on all kinds of surfaces, results in a slightly larger exponent z, but\nfitting by an exponential function is quite good too. Lattice expansion is\nfavoured on rough surfaces but increasing incoming atom kinetic energy weakens\nthis effect.",
        "positive": "Electric and magnetic fields tuned spin-polarized topological phases in\n  two-dimensional ferromagnetic MnBi$_4$Te$_7$: Applying electric or magnetic fields is widely used to not only create and\nmanipulate topological states but also facilitate their observations in\nexperiments. In this work, we show by first-principles calculations and\ntopological analysis that the time-reversal (TR) symmetry-broken quantum spin\nHall (QSH) state emerges in a two-dimensional ferromagnetic MnBi$_4$Te$_7$\nmonolayer. This TR-symmetry broken QSH phase possesses a highly tunable\nnontrivial band gap under an external electric field (or tuning interlayer\ndistance). Furthermore, based on the Wannier-function-based tight-binding\napproach, we reveal that a topological phase transition from the TR-symmetry\nbroken QSH phase to the quantum anomalous Hall (QAH) phase occurs with the\nincrease of magnetic fields. Besides, we also find that a reverse electric\nfields can facilitate the realization of QAH phase. Our work not only uncovers\nthe ferromagnetic topological properties the MnBi$_4$Te$_7$ monolayer tuned by\nelectric and magnetic fields, but also can stimulate further applications to\nspintronics and topological devices."
    },
    {
        "anchor": "Valence Fluctuation in CeMo2Si2C: We report on the valence fluctuation of Ce in CeMo$_{2}$Si$_{2}$C as studied\nby means of magnetic susceptibility $\\chi(T)$, specific heat $C(T)$, electrical\nresistivity $\\rho(T)$ and x-ray absorption spectroscopy. Powder x-ray\ndiffraction revealed that CeMo$_{2}$Si$_{2}$C crystallizes in\nCeCr$_{2}$Si$_{2}$C-type layered tetragonal crystal structure (space group\n\\textit{P4/mmm}). The unit cell volume of CeMo$_{2}$Si$_{2}$C deviates from the\nexpected lanthanide contraction, indicating non-trivalent state of Ce ions in\nthis compound. The observed weak temperature dependence of the magnetic\nsusceptibility and its low value indicate that Ce ions are in valence\nfluctuating state. The formal $L_{III}$ Ce valence in CeMo$_{2}$Si$_{2}$C\n$<$$\\widetilde{\\nu}$$>$ = 3.11 as determined from x-ray absorption spectroscopy\nmeasurement is well bellow the value $<$$\\widetilde{\\nu}$$> \\simeq$ 3.4 in\ntetravalent Ce compound CeO$_{2}$. The temperature dependence of specific heat\ndoes not show any anomaly down to 1.8 K which rules out any magnetic ordering\nin the system. The Sommerfeld coefficient obtained from the specific heat data\nis $\\gamma$ = 23.4 mJ/mol\\,K$^{2}$. The electrical resistivity follows the\n$T{^2}$ behavior in the low temperature range below 35 K confirming a Fermi\nliquid behavior. Accordingly both the Kadowaki Wood ratio $A/\\gamma^{2}$ and\nthe Sommerfeld Wilson ratio $\\chi(0)/\\gamma$ are in the range expected for\nFermi-liquid systems. In order to get some information on the electronic\nstates, we calculated the band structure within the density functional theory,\neventhough this approach is not able to treat 4f electrons accurately. The\nnon-$f$ electron states crossing the Fermi level have mostly Mo 4d character.\nThey provide the states with which the 4f sates are strongly hybridized,\nleading to the intermediate valent state.",
        "positive": "Conjugate gradient methods in micromagnetics: Conjugate gradient methods for energy minimization in micromagnetics are\ncompared. When the step length in the line search is controlled, conjugate\ngradient techniques are a fast and reliable way to compute the hysteresis\nproperties of permanent magnets. The method is applied to investigate\ndemagnetizing effects in NdFe12 based permanent magnets. The reduction of the\ncoercive field by demagnetizing effects is 1.4 T at 450 K."
    },
    {
        "anchor": "THz-driven ultrafast spin-lattice scattering in amorphous metallic\n  ferromagnets: We use single-cycle THz fields and the femtosecond magneto-optical Kerr\neffect to respectively excite and probe the magnetization dynamics in two\nthin-film ferromagnets with different lattice structure: crystalline Fe and\namorphous CoFeB. We observe Landau-Lifshitz-torque magnetization dynamics of\ncomparable magnitude in both systems, but only the amorphous sample shows\nultrafast demagnetization caused by the spin-lattice depolarization of the\nTHz-induced ultrafast spin current. Quantitative modelling shows that such\nspin-lattice scattering events occur on similar time scales than the\nconventional spin conserving electronic scattering ($\\sim30$ fs). This is\nsignificantly faster that optical laser-induced demagnetization. THz\nconductivity measurements point towards the influence of lattice disorder in\namorphous CoFeB as the driving force for enhanced spin-lattice scattering.",
        "positive": "The role of hydrogen in room-temperature ferromagnetism at graphite\n  surfaces: We present a x-ray dichroism study of graphite surfaces that addresses the\norigin and magnitude of ferromagnetism in metal-free carbon. We find that, in\naddition to carbon $\\pi$ states, also hydrogen-mediated electronic states\nexhibit a net spin polarization with significant magnetic remanence at room\ntemperature. The observed magnetism is restricted to the top $\\approx$10 nm of\nthe irradiated sample where the actual magnetization reaches $ \\simeq 15$ emu/g\nat room temperature. We prove that the ferromagnetism found in metal-free\nuntreated graphite is intrinsic and has a similar origin as the one found in\nproton bombarded graphite."
    },
    {
        "anchor": "Signature of electromagnetic quantum fluctuations in exciton physics: Quantum fluctuations of the electromagnetic field are known to produce the\natomic Lamb shift. We here reveal their iconic signature in semiconductor\nphysics, through the blue-shift they produce to optically bright excitons, thus\nlifting the energy of these excitons above their dark counterparts. The\nelectromagnetic field here acts in its full complexity: in addition to the\nlongitudinal part via interband \\textit{virtual Coulomb} processes, the\ntransverse part -- which has been missed up to now -- also acts via resonant\nand nonresonant \\textit{virtual photons}. These two parts beautifully combine\nto produce a bright exciton blue-shift independent of the exciton wave-vector\ndirection. Our work readily leads to a striking prediction: long-lived excitons\nmust have a small bright-dark splitting. Although the analogy between exciton\nand hydrogen atom could lead us to see the bright exciton shift as a Lamb\nshift, this is not fully so: the atom shift entirely comes from virtual\nphotons, whereas the Coulomb interaction also contributes to the exciton shift\nthrough the so-called \"electron-hole exchange\".",
        "positive": "Can experiment determine the stacking fault energy of metastable alloys?: Stacking fault energy (SFE) plays an important role in deformation mechanisms\nand mechanical properties of face-centered cubic (fcc) metals and alloys. In\nmetastable fcc alloys, the SFEs determined from density functional theory (DFT)\ncalculations and experimental methods often have opposite signs. Here, we show\nthat the negative SFE by DFT reflects the thermodynamic instability of the fcc\nphase relative to the hexagonal close-packed one; while the experimentally\ndetermined SFEs are restricted to be positive by the models behind the indirect\nmeasurements. We argue that the common models underlying the experimental\nmeasurements of SFE fail in metastable alloys. In various concentrated solid\nsolutions, we demonstrate that the SFEs obtained by DFT calculations correlate\nwell with the primary deformation mechanisms observed experimentally, showing a\nbetter resolution than the experimentally measured SFEs. Furthermore, we\nbelieve that the negative SFE is important for understanding the abnormal\nbehaviors of partial dislocations in metastable alloys under deformation. The\npresent work advances the fundamental understanding of SFE and its relation to\nplastic deformations, and sheds light on future alloy design by physical\nmetallurgy."
    },
    {
        "anchor": "Investigation of Magnetic Anisotropy and Heat Dissipation in Thin Films\n  of Compensated Antiferromagnet CuMnAs by Pump-probe Experiment: We recently reported on a method to determine the easy axis position in a 10\nnm thick film of the fully compensated antiferromagnet CuMnAs. The film had a\nuniaxial magnetic anisotropy and the technique utilized a magneto-optical pump\nand probe experiment [Nature Photonics 11, 91 (2017)]. In this contribution we\ndiscuss the applicability of this method for the investigation of a broader set\nof epitaxial CuMnAs films having different thicknesses. This work reveals that\nthe equilibrium magnetic anisotropy can be studied only in samples where this\nanisotropy is rather strong. However, in the majority of CuMnAs films, the\nimpact of a strong pump pulse induces nano-fragmentation of the magnetic\ndomains and, therefore, the magnetic anisotropy measured by the pump-probe\ntechnique differs substantially from that in the equilibrium conditions. We\nalso demonstrate that optical pump-probe experiment can be used very\nefficiently to study the local heating and heat dissipation in CuMnAs epitaxial\nlayers. In particular, we determined the electron-phonon relaxation time in\nCuMnAs. We also observed that for a local film heating by a focused laser the\nthinner films are heated more, but the heat is dissipated considerably faster\nthan in the case of thicker films. This illustrates that the optical pump-probe\nexperiment is a valuable characterization tool for the heat management\noptimization in the CuMnAs memory devices and can be applied in a similar way\nto those used during heat-assisted magnetic recording (HAMR) technology\ndevelopment for the latest generation of hard drive disks.",
        "positive": "Exceptionally high phonon-limited carrier mobility in BX (X = P, As, Sb)\n  monolayers: Ideal two-dimensional (2D) semiconductors with high mobility comparable to\nthree-dimensional (3D) Si or GaAs are still lacking, hindering the development\nof high-performance 2D devices. Here in this work, using first-principles\ncalculations and considering all the electron-phonon couplings, we show that\nmonolayer BX (X = P, As, Sb) with honeycomb lattices have intrinsic\nphonon-limited carrier mobility reaching record-high values of 1200-14000\n$cm^2V^{-1}s^{-1}$ at room temperature. Despite being polar and the band edges\nlocated at the K point with multiple valleys, these three systems unusually\nhave small carrier scattering rates. Detailed analysis shows that, both the\nintravalley scattering and the intervalley scattering between two equivalent K\npoints are weak, which can be understood from the large mismatch between the\nelectron bands and phonon spectrum and suppressed electron-phonon coupling\nstrength. Furthermore, we reveal the general trend of mobility increase from BP\nto BAs and to BSb and conclude that: smaller effective masses, larger sound\nvelocities, higher optical phonon energies, heavy atomic masses, and\nout-of-plane orbitals tend to result in small match between the electron and\nphonon bands, small electron-phonon coupling strengths, and thus high mobility.\nOur work demonstrates that 2D semiconductors can achieve comparable carrier\nmobility to 3D GaAs, thus opening doors to 2D high-performance electronic\ndevices."
    },
    {
        "anchor": "Simulating complex crystal structures using the phase-field crystal\n  model: We introduce a phase-field crystal model that creates an array of complex\nthree- and two-dimensional crystal structures via a numerically tractable\nthree-point correlation function. The three-point correlation function is\ndesigned in order to energetically favor the principal interplanar angles of a\ntarget crystal structure. This is achieved via an analysis performed by\nexamining the crystal's structure factor. This approach successfully yields\nenergetically stable simple cubic, diamond cubic, simple hexagonal, graphene\nlayers, and CaF$_2$ crystals. To illustrate the ability of the method to yield\na particularly complex and technologically important crystal structure, we show\nhow this three-point correlation function method can be used to generate\nperovskite crystals.",
        "positive": "Quantum-continuum simulation of the electrochemical response of\n  pseudocapacitor electrodes from realistic conditions: Pseudocapacitors are energy-storage devices characterized by fast and\nreversible redox reactions that enable them to store large amounts of\nelectrical energy at high rates. We simulate the response of pseudocapacitive\nelectrodes under realistic conditions to identify the microscopic factors that\ndetermine their performance, focusing on ruthenia (RuO2) as a prototypical\nelectrode material. Electronic-structure methods are used together with a\nself-consistent continuum solvation (SCCS) model to build a complete dataset of\nfree energies as the surface of the charged electrode is gradually covered with\nprotons under applied voltage. The resulting dataset is exploited to compute\nhydrogen-adsorption isotherms and charge-voltage responses by means of\ngrand-canonical sampling, finding close agreement with experimental\nvoltammetry. These simulations reveal that small changes on the order of 5\n{\\mu}F/cm2 in the intrinsic double-layer capacitance of the\nelectrode-electrolyte interface can induce variations of up to 40 {\\mu}F/cm2 in\nthe overall pseudocapacitance."
    },
    {
        "anchor": "On gradient enriched elasticity theories: A reply to \"Comment on 'On\n  non-singular crack fields in Helmholtz type enriched elasticity theories' \"\n  and important theoretical aspects: The Comment by Aifantis that criticizes the article 'On non-singular crack\nfields in Helmholtz type enriched elasticity theories' [Lazar, M., Polyzos, D.,\n2014. Int. J. Solids Struct. doi: 10.1016/j.ijsolstr.2014.01.002] is refuted by\nmeans of clear and straightforward arguments. Important theoretical aspects of\ngradient enriched elasticity theories which emerge in this work are also\ndiscussed.",
        "positive": "Giant magnetoresistance in antiferromagnetic Mn$_2$Au-based tunnel\n  junction: Recent studies on the electrical switching of tetragonal antiferromagnet\n(AFM) via N{\\'e}el spin-orbit torque have paved the way for the economic use of\nantiferromagnetic materials. The most difficult obstacle that presently limits\nthe application of antiferromagnetic materials in spintronics, especially in\nmemory storage applications, could be the small and fragile magnetoresistance\n(MR) in the AFM-based nanostructure. In this study, we investigated the spin\ntransports in Mn$_2$Au-based tunnel junctions based onthe first-principle\nscattering theory. Giant MRs more than $1000\\%$ are predicted in some\nFe/MgO/Ag/Mn$_2$Au/Ta junctions that are about the same order as that in an\nMgO-based ferromagnetic tunnel junction with same barrier thickness. The\ninterplay of the spin filtering effect, the quantum well resonant states, and\nthe interfacial resonant states could be responsible for the unusual giant and\nrobust MRs observed in these Mn$_2$Au-based junctions."
    },
    {
        "anchor": "First-principles study of ternary fcc solution phases from special\n  quasirandom structures: In the present work, ternary Special Quasirandom Structures (SQSs) for a fcc\nsolid solution phase are generated at different compositions,\n$x_A=x_B=x_C=\\tfrac{1}{3}$ and $x_A=\\tfrac{1}{2}$, $x_B=x_C=\\tfrac{1}{4}$,\nwhose correlation functions are satisfactorily close to those of a random fcc\nsolution. The generated SQSs are used to calculate the mixing enthalpy of the\nfcc phase in the Ca-Sr-Yb system. It is observed that first-principles\ncalculations of all the binary and ternary SQSs in the Ca-Sr-Yb system exhibit\nvery small local relaxation. It is concluded that the fcc ternary SQSs can\nprovide valuable information about the mixing behavior of the fcc ternary solid\nsolution phase. The SQSs presented in this work can be widely used to study the\nbehavior of ternary fcc solid solutions.",
        "positive": "Tight-binding : the correction of the simple d-band inconsistencies: The physical properties of the transitional metals from the bulk to the\nnanoparticles cannot be calculated accurately using a tight-binding\napproximation restricted to a simple d-band. The investigations on this\napproximation show the limitations, leading to a wrong cohesive energy compared\nto an all-electron tight-binding basis calculation. These investigations\nthrough the second moment approximation, the charge neutrality and the Stoner\nmodel allow us to derive the appropriate corrections to these inconsistencies."
    },
    {
        "anchor": "High pressure structural study of fluoro perovskite CsCdF3 upto 60 GPa:\n  A combined experimental and theoretical study: The structural behaviour of CsCdF3 under pressure is investigated by means of\ntheory and experiment. High-pressure powder x-ray diffraction experiments were\nperformed up to a maximum pressure of 60 GPa using synchrotron radiation. The\ncubic $Pm\\bar{3}m$ crystal symmetry persists throughout this pressure range.\nTheoretical calculations were carried out using the full-potential linear\nmuffin-tin orbital method within the local density approximation and the\ngeneralized gradient approximation for exchange and correlation effects. The\ncalculated ground state properties -- the equilibrium lattice constant, bulk\nmodulus and elastic constants -- are in good agreement with experimental\nresults. Under ambient conditions, CsCdF3 is an indirect gap insulator with the\ngap increasing under pressure.",
        "positive": "Hexagonal spiral growth in the absence of a substrate: Experiments on the formation of spiraling hexagons (350 - 1000 nm in width)\nfrom a solution of nanoparticles are presented. Transmission electron\nmicroscopy images of the reaction products of chemically synthesized cadmium\nnanocrystals indicate that the birth of the hexagons proceeds without\nassistance from static screw or edge dislocatons, that is, they spiral without\nconstraints provided by an underlying substrate. Instead, the apparent growth\nmechanism relies on what we believe is a dynamical dislocation identified as a\ndense aggregate of small nanocrystals that straddles the spiraling hexagon at\nthe crystal surface. This nanocrystal bundle, which we term the \"feeder\", also\nappears to release nanocrystals into the spiral during the growth process."
    },
    {
        "anchor": "Homogenization of Halide Distribution and Carrier Dynamics in Alloyed\n  Organic-Inorganic Perovskites: Perovskite solar cells have shown remarkable efficiencies beyond 22%, through\norganic and inorganic cation alloying. However, the role of alkali-metal\ncations is not well-understood. By using synchrotron-based nano-X-ray\nfluorescence and complementary measurements, we show that when adding RbI\nand/or CsI the halide distribution becomes homogenous. This homogenization\ntranslates into long-lived charge carrier decays, spatially homogenous carrier\ndynamics visualized by ultrafast microscopy, as well as improved photovoltaic\ndevice performance. We find that Rb and K phase-segregate in highly\nconcentrated aggregates. Synchrotron-based X-ray-beam-induced current and\nelectron-beam-induced current of solar cells show that Rb clusters do not\ncontribute to the current and are recombination active. Our findings bring\nlight to the beneficial effects of alkali metal halides in perovskites, and\npoint at areas of weakness in the elemental composition of these complex\nperovskites, paving the way to improved performance in this rapidly growing\nfamily of materials for solar cell applications.",
        "positive": "Electronic polarization in the ultrasoft pseudopotential formalism: An expression is given for the electronic polarization of an insulating\ncrystal within the ultrasoft pseudopotential scheme. The pseudopotential\ncharge-augmentation terms modify the usual Berry-phase expression, and also\ngive rise to a second term that takes the form of a conventional expectation\nvalue."
    },
    {
        "anchor": "The role of frequency and impedance contrasts in bandgap closing and\n  formation patterns of axially-vibrating phononic crystals: Bandgaps, or frequency ranges of forbidden wave propagation, are a hallmark\nof Phononic Crystals (PnCs). Unlike their lattice counterparts, PnCs taking the\nform of continuous structures exhibit an infinite number of bandgaps of varying\nlocation, bandwidth, and distribution along the frequency spectrum. While these\nbandgaps are commonly predicted from benchmark tools such as the Bloch-wave\ntheory, the conditions that dictate the patterns associated with bandgap\nsymmetry, attenuation, or even closing in multi-bandgap PnCs remain an enigma.\nIn this work, we establish these patterns in one-dimensional rods undergoing\nlongitudinal motion via a canonical transfer-matrix-based approach. In doing\nso, we connect the conditions governing bandgap formation and closing to their\nphysical origins in the context of the Bragg condition (for infinite media) and\nnatural resonances (for finite counterparts). The developed framework uniquely\ncharacterizes individual bandgaps within a larger dispersion spectrum\nregardless of their parity (i.e., odd vs even bandgaps) or location (low vs\nhigh-frequency), by exploiting dimensionless constants of the PnC unit cell\nwhich quantify the different contrasts between its constitutive layers. These\ndevelopments are detailed for a bi-layered PnC and then generalized for a PnC\nof any number of layers by increasing the model complexity. We envision this\nmathematical development to be a future standard for the realization of\nhierarchically-structured PnCs with prescribed and finely tailored bandgap\nprofiles.",
        "positive": "Thermal conductivity of graphene mediated by strain and size: Based on first-principles calculations and full iterative solution of the\nlinearized Boltzmann-Peierls transport equation for phonons within three-phonon\nscattering framework, we characterize the lattice thermal conductivities\n$\\kappa$ of strained and unstrained graphene. We find $\\kappa$ converges to\n5450 W/m-K for infinite unstrained graphene, while $\\kappa$ diverges for\nstrained graphene with increasing system size at room temperature. The\ndifferent $\\kappa$ behaviors for these systems are further validated\nmathematically through phonon lifetime analysis. Flexural acoustic phonons are\nthe dominant heat carriers in both unstrained and strained graphene within the\ntemperature considered. Ultralong mean free paths of flexural phonons\ncontribute to finite size effects on $\\kappa$ for samples as large as 8 cm at\nroom temperature. The calculated size-dependent and temperature-dependent\n$\\kappa$ for finite samples agree well with experimental data, demonstrating\nthe ability of the present approach to predict $\\kappa$ of larger graphene\nsample. Tensile strain hardens the flexural modes and increases their\nlifetimes, causing interesting dependence of $\\kappa$ on sample size and strain\ndue to the competition between boundary scattering and intrinsic phonon-phonon\nscattering. These findings shed light on the nature of thermal transport in\ntwo-dimensional materials and may guide predicting and engineering $\\kappa$ of\ngraphene by varying strain and size."
    },
    {
        "anchor": "Berry Curvature and Phonon Hall Effect: We establish the general phonon dynamics of magnetic solids by incorporating\nthe Mead-Truhlar correction in the Born-Oppenheimer approximation. The\neffective magnetic-field acting on the phonons naturally emerges, giving rise\nto the phonon Hall effect. A general formula of the intrinsic phonon Hall\nconductivity is obtained by using the corrected Kubo formula with the energy\nmagnetization contribution incorporated properly. The resulting phonon Hall\nconductivity is fully determined by the phonon Berry curvature and the\ndispersions. Based on the formula, the topological phonon system could be\nrigorously defined. In the low temperature regime, we predict that the phonon\nHall conductivity is proportional to $T^{3}$ for the ordinary phonon systems,\nwhile that for the topological phonon systems has the linear $T$ dependence\nwith the quantized temperature coefficient.",
        "positive": "Dielectric response of soft mode in ferroelectric SrTiO3: We report far-infrared dielectric properties of powder form ferroelectric\nSrTiO3. Terahertz time-domain spectroscopy (THz-TDS) measurement reveals that\nthe low-frequency dielectric response of SrTiO3 is a consequence of the lowest\ntransverse optical (TO) soft mode TO1 at 2.70 THz (90.0 1/cm), which is\ndirectly verified by Raman spectroscopy. This result provides a better\nunderstanding of the relation of low-frequency dielectric function with the\noptical phonon soft mode for ferroelectric materials. Combining THz-TDS with\nRaman spectra, the overall low-frequency optical phonon response of SrTiO3 is\npresented in an extended spectral range from 6.7 1/cm to 1000.0 1/cm."
    },
    {
        "anchor": "Rate-Dependent Avalanche Size in Athermally Sheared Amorphous Solids: We perform an extensive numerical study of avalanche behavior in a 2D LJ\nglass at T=0, sheared at finite strain rates $\\dot\\gamma$. From the finite size\nanalysis of stress fluctuations and of transverse diffusion we show that\nflip-flip correlations remain relevant at all realistic strain rates. We\npredict that the avalanche size scales as $\\dot\\gamma^{-1/d}$, with $d$ the\nspace dimension.",
        "positive": "Valorizing the carbon byproduct of methane pyrolysis in batteries: While low-cost natural gas remains abundant, the energy content of this fuel\ncan be utilized without greenhouse gas emissions through the production of\nmolecular hydrogen and solid carbon via methane pyrolysis. In the absence of a\ncarbon tax, methane pyrolysis is not economically competitive with current\nhydrogen production methods unless the carbon byproducts can be valorized. In\nthis work, we assess the viability of the carbon byproduct produced from\nmethane pyrolysis in molten salts as high-value-added anode or conductive\nadditive for secondary Li-ion and Na-ion batteries. Raman characterization and\nelectrochemical differential capacity analysis demonstrate that the use of\nmolten salt mixtures with catalytically-active FeCl3- or MnCl2 result in more\ngraphitic carbon co-products. These graphitic carbons exhibit the best\nelectrochemical performance (up to 272 mAh/g of reversible capacity) when used\nas Li-ion anodes. For all carbon samples studied here, disordered carbon\ndomains and retained salt species trapped and/or intercalated into the carbon\nstructure were identified by X-ray photoelectron and multinuclear solid-state\nnuclear magnetic resonance spectroscopy. The latter lead to reduced\nelectrochemical activity and reversibility, and poorer rate performance\ncompared to commercial carbon anodes. The electronic conductivity of the\npyrolyzed carbons is found to be highly dependent on their purity, with the\npurest carbon exhibiting an electronic conductivity nearly on par with that of\ncommercial carbon additives. These findings suggest that more effective removal\nof the salt catalyst could enable applications of these carbons in secondary\nbatteries, providing a financial incentive for the large-scale implementation\nof methane pyrolysis for low-carbon hydrogen production."
    },
    {
        "anchor": "Optimizing Transistor Performance of Percolating Carbon Nanotube\n  Networks: In percolating networks of mixed metallic and semiconducting CNTs, there is a\ntradeoff between high on-current (dense networks) and high on/off ratio (sparse\nnetworks in which the metallic CNT fraction is not percolating). Experiments on\ndevices in a transistor configuration and Monte Carlo simulations were\nperformed to determine the scaling behavior of device resistivity as a function\nof channel length (L) for CNT density p in the range 0.04 - 1.29 CNT/{\\mu}m^2\nin the on- and off-states. Optimized devices with field-effect mobility up to\n50 cm^2/Vs at on/off ratio > 10^3 were obtained at W = 50 {\\mu}m, L > 70 {\\mu}m\nfor p = 0.54 - 0.81 CNTs/{\\mu}m^2.",
        "positive": "Thermodynamic dislocation theory for non-uniform plastic deformations: The present paper extends the thermodynamic dislocation theory developed by\nLanger, Bouchbinder, and Lookmann to non-uniform plastic deformations. The free\nenergy density as well as the positive definite dissipation function are\nproposed. The governing equations are derived from the variational equation. As\nillustration, the problem of plane strain constrained shear of single crystal\ndeforming in single slip is solved within the proposed theory."
    },
    {
        "anchor": "Zr-Co-Al bulk metallic glass composites containing B2 ZrCo via rapid\n  quenching and annealing: As a promising remedy for overcoming the limited ductility and work softening\nof bulk metallic glasses (BMGs), BMG composites incorporating a B2 crystalline\nphase have attracted considerable attention. Here, we explore the formation of\nZr-Co-Al BMG composites by quenching alloys Zr$_{55}$Co$_{31}$Al$_{14}$,\nZr$_{54.5}$Co$_{33.5}$Al$_{12}$, Zr$_{53.5}$Co$_{36.5}$Al$_{10}$,\nZr$_{52.5}$Co$_{37.5}$Al$_{10}$, and Zr$_{43}$Co$_{43}$Al$_{14}$. We found the\nfirst alloy fully amorphous whereas the fifth was fully crystallized upon\nquenching. The other three were quenched to generate composite structures, with\na higher fraction of B2 ZrCo phase with increasing Co/Zr ratio and decreasing\nAl content. For comparison, the formation of B2 ZrCo in annealed\nZr$_{55}$Co$_{31}$Al$_{14}$ was also studied. For both approaches the influence\nof crystalline phases on hardness was examined.",
        "positive": "The Dzyaloshinskii-Moriya interaction is under control: an orchestrated\n  flip of the chiral link between structure and magnetism for\n  Fe$_{1-x}$Co$_x$Si: Monosilicides of 3d-metals frequently show a chiral magnetic ordering with\nthe absolute configuration defined by the chirality of the crystal structure\nand the sign of the Dzyaloshinskii-Moriya interaction (DMI). Structural and\nmagnetic chiralities are probed here for Fe$_{1-x}$Co$_x$Si series and their\nmutual relationship is found to be dependent on the chemical composition. The\nchirality of crystal structure was previously shown to be governed by crystal\ngrowth, and the value of the DMI is nearly the same for all monosilicides of\nFe, Co and Mn. Our findings indicate that the sign of the DMI in\nFe$_{1-x}$Co$_x$Si is controlled by the Co composition $x$, thus, opening a\nroute towards controlled design of chiral spintronics devices."
    },
    {
        "anchor": "Resonance-enhanced optical nonlinearity in the Weyl semimetal TaAs: While all media can exhibit first-order conductivity describing current\nlinearly proportional to electric field, $E$, the second-order conductivity,\n$\\sigma^{(2)}$ , relating current to $E^2$, is nonzero only when inversion\nsymmetry is broken. Second order nonlinear optical responses are powerful tools\nin basic research, as probes of symmetry breaking, and in optical technology as\nthe basis for generating currents from far-infrared to X-ray wavelengths. The\nrecent surge of interest in Weyl semimetals with acentric crystal structures\nhas led to the discovery of a host of $\\sigma^{(2)}$ -related phenomena in this\nclass of materials, such as polarization-selective conversion of light to dc\ncurrent (photogalvanic effects) and the observation of giant second-harmonic\ngeneration (SHG) efficiency in TaAs at photon energy 1.5 eV. Here, we present\nmeasurements of the SHG spectrum of TaAs revealing that the response at 1.5 eV\ncorresponds to the high-energy tail of a resonance at 0.7 eV, at which point\nthe second harmonic conductivity is approximately 200 times larger than seen in\nthe standard candle nonlinear crystal, GaAs. This remarkably large SHG response\nprovokes the question of ultimate limits on $\\sigma^{(2)}$ , which we address\nby a new theorem relating frequency-integrated nonlinear response functions to\nthe third cumulant (or \"skewness\") of the polarization distribution function in\nthe ground state. This theorem provides considerable insight into the factors\nthat lead to the largest possible second-order nonlinear response, specifically\nshowing that the spectral weight is unbounded and potentially divergent when\nthe possibility of next-neighbor hopping is included.",
        "positive": "Anomalous Raman Response in 2D Magnetic FeTe under Uniaxial Strain:\n  Tetragonal and Hexagonal Polymorphs: Two-dimensional (2D) Fe-chalcogenides have emerged with rich structures,\nmagnetisms and superconductivities, which sparked the growing research\ninterests in the torturous transition mechanism and tunable properties for\ntheir potential applications in nanoelectronics. Uniaxial strain can produce a\nlattice distortion to study symmetry breaking induced exotic properties in 2D\nmagnets. Herein, the anomalous Raman spectrum of 2D tetragonal (t-) and\nhexagonal (h-) FeTe were systematically investigated via uniaxial strain\nengineering strategy. We found that both t- and h-FeTe keep the structural\nstability under different uniaxial tensile or compressive strain up to +/-\n0.4%. Intriguingly, the lattice vibrations along both in-plane and out-of-plane\ndirections exceptionally hardened (softened) under tensile (compressive)\nstrain, distinguished from the behaviors of many conventional 2D systems.\nFurthermore, the difference in thickness-dependent strain effect can be well\nexplained by their structural discrepancy between two polymorphs of FeTe. Our\nresults could provide a unique platform to elaborate the vibrational properties\nof many novel 2D materials."
    },
    {
        "anchor": "Efficient Learning Strategy for Predicting Glass Forming Ability in\n  Imbalanced Datasets of Bulk Metallic Glasses: The prediction of glass forming ability (GFA) and various properties in bulk\nmetallic glasses (BMGs) pose a challenge due to the unique disordered atomic\nstructure in this type of materials. Machine learning shows the potential\nability to find a way out. However, the training set from the experimental data\nof BMGs faces the issue of data imbalance, including the distribution of data\nrelated to elements, the range of performance data, and the distribution of\nsparse and dense data area in each specific system. In this work, the origin of\nthe data imbalance and its impact on the GFA prediction ability of machine\nlearning models are analyzed. We propose the solutions by training the model\nusing the pruned dataset to mitigate the imbalance and by performing an active\nexperimental iterative learning to compensate for the information loss\nresulting from data reduction. The strategy is proved in Zr-Al-Cu system, and\nthe automated workflow has been established. It effectively avoids the\nprediction results from trapping into the intensive training data area or from\ninducing by the data distribution of similar element systems. This approach\nwill expedite the development of new BMGs compositions especially for\nunexplored systems.",
        "positive": "Thermodynamic Stability of Mg-based Ternary Long-Period Stacking Ordered\n  Structures: Mg alloys containing long-period stacking ordered (LPSO) structures exhibit\nremarkably high tensile yield strength and ductility. They have been found in a\nvariety of ternary Mg systems of the general form Mg-XL-XS, where XL and XS are\nelements larger and smaller than Mg, respectively. In this work, we examine the\nthermodynamic stability of these LPSO precipitates with density functional\ntheory, using a newly proposed structure model based on the inclusion of a Mg\ninterstitial atom. We predict the stabilities for 14H and 18R LPSO structures\nfor many Mg-XL-XS ternary systems: 85 systems consisting of XL=rare earths (RE)\nSc,Y,La-Lu and XS=Zn,Al,Cu,Co,Ni. We predict thermodynamically stable LPSO\nphases in all systems where LPSO structures are observed. In addition, we\npredict several stable LPSO structures in new, as-yet-unobserved Mg-RE-XS\nsystems. Many non-RE XL elements are also explored on the basis of size\nmismatch between Mg and XL, including Tl,Sb,Pb,Na,Te,Bi,Pa,Ca,Th,K,Sr --- an\nadditional 55 ternary systems. XL=Ca, Sr, and Th are predicted to be most\npromising to form stable LPSO phases, particularly with XS=Zn. Lastly, several\npreviously observed trends amongst known XL elements are examined. We find that\nfavorable mixing energy between Mg and XL on the FCC lattice and the size\nmismatch together serve as excellent criteria determining XL LPSO formation."
    },
    {
        "anchor": "Lattice constant variation and complex formation in zincblende Gallium\n  Manganese Arsenide: We perform high resolution X-ray diffraction on GaMnAs mixed crystals as well\nas on GaMnAs/GaAs and GaAs/MnAs superlattices for samples grown by low\ntemperature molecular beam epitaxy under different growth conditions. Although\nall samples are of high crystalline quality and show narrow rocking curve\nwidths and pronounced finite thickness fringes, the lattice constant variation\nwith increasing manganese concentration depends strongly on the growth\nconditions: For samples grown at substrate temperatures of 220 and 270 degrees\nC the extrapolated relaxed lattice constant of Zincblende MnAs is 0.590 nm and\n0.598 nm respectively. This is in contrast to low temperature GaAs, for which\nthe lattice constant decreases with increasing substrate temperature.",
        "positive": "Ceramics with metallic lustre decoration. A detailed knowledge of\n  Islamic productions from 9th century until Renaissance: This paper describes research on the technological evolution of glazed\nceramics with a metallic lustre decoration starting from their emergence in the\nNear East until the Hispano-Moresque productions. That research covers the main\nknown Islamic production sites and periods: Abbasid (Mesopotamia); Fatimid\n(Egypt); Timurid, Mongol, and Safavid (Iran); Ayyubid and Mamluk (Syria);\nNasrid and Hispano-Moresque (Spain). It was allowed by the access to more than\nhundred full preserved objects or fragments supplied by French national museums\n(Mus\\'ee du Louvre DAI, Mus\\'ee national du Moyen Age, Mus\\'ee national de\nC\\'eramique). The characterisation of the composition and structure of the\nceramics and of their decoration is mostly done through non-destructive\nanalyses methods. The thickness and metal content of the surface lustre layers\nare quantified thanks to ion beam analyses performed on a particle accelerator:\nPIXE (particle-induced X-ray emission) for the terracotta and glazes\ncomposition and RBS (Rutherford backscattering spectrometry) for the thickness\nand metal content of the lustre surface layers. The preliminary results show\nthat the features of the decorated ceramics have undergone dramatic variations\nwhen transmitted from a production to another, not only, as expected, in the\ncomposition of terracotta and glazes, but also in the thickness, the structure\nand the composition distribution of the lustre layers."
    },
    {
        "anchor": "Accelerating GW calculations of point defects with the defect-patched\n  screening approximation: The GW approximation has been widely accepted as an ab initio tool for\ncalculating defect levels with many-electron effect included. However, the GW\nsimulation cost increases dramatically with the system size, and,\nunfortunately, large supercells are often required to model low-density defects\nthat are experimentally relevant. In this work, we propose to accelerate GW\ncalculations of point defects by reducing the simulation cost of the\nmany-electron screening, which is the primary computational bottleneck. The\nrandom-phase approximation of many-electron screening is divided into two\nparts: one is the intrinsic screening, calculated using a unit cell of pristine\nstructures, and the other is the defect-induced screening, calculated using the\nsupercell within a small energy window. Depending on specific defects, one may\nonly need to consider the intrinsic screening or include the defect\ncontribution. This approach avoids the summation of many conductions states of\nsupercells and significantly reduces the simulation time. We have applied it to\ncalculating various point defects, including neutral and charged defects in\ntwo-dimensional and bulk systems with small or large bandgaps. The results\nconsist with those from the direct GW simulations, and the agreements are\nfurther improved at the dilute-defect limit, which is experimentally relevant\nbut extremely challenging for direct GW simulations. This defect-patched\nscreening approach not only clarifies the roles of defects in many-electron\nscreening but also paves the way to fast screen defect structures/materials for\nnovel applications, including single-photon sources, quantum qubits, and\nquantum sensors.",
        "positive": "Structural, electronic, and optical properties of the C-C complex in\n  bulk silicon from first principles: The structure of the CiCs complex in silicon has long been the subject of\ndebate. Numerous theoretical and experimental studies have attempted to shed\nlight on the properties of these defects that are at the origin of the light\nemitting G-center. These defects are relevant for applications in lasing, and\nit would be advantageous to control their formation and concentration in bulk\nsilicon. It is therefore essential to understand their structural and\nelectronic properties. In this paper, we present the structural, electronic,\nand optical properties of four possible configurations of the CiCs complex in\nbulk silicon, namely the A-, B-, C-, and D-forms. The configurations were\nstudied by density functional theory (DFT) and many-body perturbation theory\n(MBPT). Our results suggest that the C-form was misinterpreted as a B-form in\nsome experiments. Our optical investigation also tends to exclude any\ncontribution of A- and B-forms to light emission. Taken together, our results\nsuggest that the C-form could play an important role in heavily carbon-doped\nsilicon."
    },
    {
        "anchor": "In situ photoacoustic characterization for porous silicon growing:\n  detection principles: There are a few methodologies to monitoring the Porous Silicon (PS) formation\nin-situ. One of these methodologies is photoacoustic. Previous works that\nreported the use of photoacoustic to study the PS formation do not provide the\nphysical explanation of the origin of the signal. In this paper, a physical\nexplanation is provided of the origin of the photoacoustic signal during the PS\netching. The incident modulated radiation and changes in the reflectance are\ntaken as thermal sources. In this paper, a useful methodology is proposed to\ndetermine the etching rate, porosity, and refractive index of a PS film by the\ndetermination of the sample thickness, using SEM images. This method was\ndeveloped by carrying out two different experiments using the same anodization\nconditions. The first experiment consisted of the growth of samples with\ndifferent etching times to prove the periodicity of the photoacoustic signal\nand the second considered the growth samples using three different wavelengths\nthat are correlated with the period of the photoacoustic signal. The last\nexperiment showed that the period of the photoacoustic signal is proportional\nto the laser wavelength.",
        "positive": "Simple machine-learned interatomic potentials for complex alloys: Developing data-driven machine-learning interatomic potentials for materials\ncontaining many elements becomes increasingly challenging due to the vast\nconfiguration space that must be sampled by the training data. We study the\nlearning rates and achievable accuracy of machine-learning interatomic\npotentials for many-element alloys with different combinations of descriptors\nfor the local atomic environments. We show that for a five-element alloy\nsystem, potentials using simple low-dimensional descriptors can reach\nmeV/atom-accuracy with modestly sized training datasets, significantly\noutperforming the high-dimensional SOAP descriptor in data efficiency,\naccuracy, and speed. In particular, we develop a computationally fast\nmachine-learned and tabulated Gaussian approximation potential (tabGAP) for\nMo-Nb-Ta-V-W alloys with a combination of two-body, three-body, and a new\nsimple scalar many-body density descriptor based on the embedded atom method."
    },
    {
        "anchor": "Observation of the Type-II Weyl Semimetal Phase in MoTe2: Topological Weyl semimetal (TWS), a new state of quantum matter, has sparked\nenormous research interest recently. Possessing unique Weyl fermions in the\nbulk and Fermi arcs on the surface, TWSs offer a rare platform for realizing\nmany exotic physical phenomena. TWSs can be classified into type-I that respect\nLorentz symmetry and type-II that do not. Here, we directly visualize the\nelectronic structure of MoTe2, a recently proposed type-II TWS. Using\nangle-resolved photoemission spectroscopy (ARPES), we unravel the unique\nsurface Fermi arcs, in good agreement with our ab-initio calculations. From\nspin-resolved ARPES measurements, we demonstrate the non-degenerate\nspin-texture of surface Fermi-arcs, thereby proving their non-trivial\ntopological nature. Our work not only lead to new understandings of the unusual\nproperties discovered in this family of compounds, but also allow for the\nfurther exploration of exotic properties and practical applications of type-II\nTWSs, as well as the interplay between superconductivity (MoTe2 was discovered\nto be superconducting recently) and their topological order.",
        "positive": "Microscopic modelling of exciton-polariton diffusion coefficients in\n  atomically thin semiconductors: In the strong light-matter coupling regime realized e.g. by integrating\nsemiconductors into optical microcavities, polaritons as new hybrid\nlight-matter quasi-particles are formed. The corresponding change in the\ndispersion relation has a large impact on optics, dynamics and transport\nbehaviour of semiconductors. In this work, we investigate the strong-coupling\nregime in hBN-encapsulated MoSe$_2$ monolayers focusing on exciton-polariton\ndiffusion. Applying a microscopic approach based on the exciton density matrix\nformalism combined with the Hopfield approach, we predict a drastic increase of\nthe diffusion coefficients by two to three orders of magnitude in the strong\ncoupling regime. We explain this behaviour by the much larger polariton group\nvelocity and suppressed polariton-phonon scattering channels with respect to\nthe case of bare excitons. Our study contributes to a better microscopic\nunderstanding of polariton diffusion in atomically thin semiconductors."
    },
    {
        "anchor": "The Structural Diversity of ABS3 Compounds with d0 Electronic\n  Configuration for the B-cation: We use first-principles density functional theory (DFT) within the local\ndensity approx- imation (LDA) to ascertain the ground state structure of real\nand theoretical compounds with the formula ABS3 (A = K, Rb, Cs, Ca, Sr, Ba, Tl,\nSn, Pb, and Bi; and B = Sc, Y, Ti, Zr, V, and Nb) under the constraint that B\nmust have a d0 electronic configuration. Our findings indicate that none of\nthese AB combinations prefer a perovskite ground state with corner-sharing BS6\noctahedra, but that they prefer phases with either edge- or face-sharing\nmotifs. Further, a simple two-dimensional structure field map created from A\nand B ionic radii provides a neat demarcation between combinations preferring\nface-sharing versus edge- sharing phases for most of these combinations. We\nthen show that by modifying the common Goldschmidt tolerance factor with a\nmultiplicative term based on the electronegativity dif- ference between A and\nS, the demarcation between predicted edge-sharing and face-sharing ground state\nphases is enhanced. We also demonstrate that, by calculating the free energy\ncontribution of phonons, some of these compounds may assume multiple phases as\nsynthesis temperatures are altered, or as ambient temperatures rise or fall.",
        "positive": "Synthesis of single-crystalline LuN films: In the nitrogen-doped lutetium hydride (Lu-H-N) system, the presence of Lu-N\nchemical bonds plays a key role in the emergence of possible room-temperature\nsuperconductivity at near ambient pressure. However, due to the synthesis of\nsingle-crystalline LuN being a big challenge, the understanding of LuN is\ninsufficient thus far. Here, we report on the epitaxial growth of\nsingle-crystalline LuN films. The crystal structures of LuN films were\ncharacterized by high-resolution X-ray diffraction. The measurement of\nlow-temperature electrical transport indicates the LuN film is semiconducting\nfrom 300 to 2 K, yielding an activation gap of $\\sim$ 0.02 eV. Interestingly,\nnegative magnetoresistances can be observed below 12 K, which can result from\nthe defects and magnetic impurities in LuN films. Our results uncover the\nelectronic and magnetic properties of single-crystalline LuN films."
    },
    {
        "anchor": "Superior visible photoelectric response with Au/Cu2NiSnS4 core-shell\n  nanocrystals: The incorporation of plasmonic metal nanostructures into semiconducting\nchalcogenides, in the form of core-shell structures, represents a promising\napproach to boosting the performance of photodetectors. In this study, we\ncombined Au nanoparticles with newly developed copper-based chalcogenides\nCu2NiSnS4 (Au/CNTS), to achieve an ultrahigh optoelectronic response in the\nvisible regime. The high-quality Au/CNTS core-shell structure was synthesized\nby developing a unique colloidal hot-injection method, which allowed excellent\ncontrol over sizes, shapes, and elemental compositions. The fabricated Au/CNTS\nhybrid core-shell structure exhibited enhanced optical absorption, carrier\nextraction efficiency, and improved photo-sensing performance, owing to the\nplasmonic-induced resonance energy transfer effect of the Au core. This effect\nled to a significant increase in carrier density between the Au core and CNTS\nshell. These values outperformed a CNTS-based gate-free visible photodetector.",
        "positive": "Soft Mode Anomalies in the Perovskite Relaxor Pb(Mg1/3Nb2/3)O3: Neutron inelastic scattering measurements of the polar TO phonon mode in the\ncubic relaxor Pb(Mg1/3Nb2/3)O3, at room temperature, reveal anomalous behavior\nsimilar to that recently observed in the Pb(Zn1/3Nb2/3)_{0.92}Ti_{0.08}O3\nsystem in which the optic branch appears to drop precipitously into the\nacoustic branch at a finite value of the momentum transfer q = 0.20\n1/Angstroms, measured from the zone center. By contrast, a recent neutron study\nshowed that PMN exhibits a normal TO phonon dispersion at 800 K. We speculate\nthis behavior is common to all relaxor materials and is the result of the\npresence of nanometer-scale polarized domains in the crystal that form below a\ntemperature Td, which effectively prevent the propagation of long wavelength (q\n= 0) phonons."
    },
    {
        "anchor": "Growth and Electrical Characterization of 2D Layered MoS2/SiC\n  Heterojunctions: The growth and electrical characterization of a heterojunction formed between\n2D layered p-MoS2 and nitrogen-doped 4H-SiC is reported. Direct growth of\np-type MoS2 films on SiC was demonstrated using chemical vapor deposition, and\nthe MoS2 films were found to be crystalline based on x-ray diffraction\nmeasurements. The resulting heterojunction was found to display rectification\nand current-voltage characteristics consistent with a p-n junction diode.\nCapacitance voltage measurements were used to determine the built-in voltage\nfor the p-MoS2/n-SiC heterojunction p-n diode. The demonstration of\nheterogeneous material integration between 2D layered semiconductors and 3D SiC\nenables a new class of heterostructures.",
        "positive": "Altering the magnetic ordering of Fe$_{3}$Ga$_{4}$ via thermal annealing\n  and hydrostatic pressure: The effects of post-synthesis annealing temperature on arc-melted samples of\nFe$_{3}$Ga$_{4}$ has been studied to investigate changes in crystallographic\nand magnetic properties induced by annealing. Results show a significant trend\nin the evolution of the (incommensurate spin density wave) ISDW-FM\n(ferromagnetic) transition temperature as a function of the refined unit cell\nvolume in annealed samples. Strikingly, this trend allowed for the tuning of\nthe transition temperature down to room-temperature (300 K) whilst maintaining\na sharp transition in temperature, opening the door to the use of\nFe$_{3}$Ga$_{4}$ in functional devices. Crystallographic analysis through\nRietveld refinement of high-resolution x-ray diffraction data has showed that\narc-melted stoichiometric Fe$_{3}$Ga$_{4}$ is multi-phase regardless of\nannealing temperature with a minor phase of FeGa$_{3}$ decreasing in phase\nfraction at higher annealing temperature. In order to validate the trend in\nISDW-FM transition temperature with regard to unit cell volume, high pressure\nmagnetometry was performed. This showed that the FM-ISDW ($\\sim$ 68 K) and\nISDW-FM ($\\sim$ 360 K) transition temperatures could be tuned, increased and\ndecreased respectively, linearly with external pressure. Thus, external\npressure and the ensuing crystallographic changes minimize the temperature\nrange of the stability of the ISDW pointing toward the importance of structural\nproperties on the mechanism for the formation of the intermediate ISDW phase.\nThese results show how this model system can be tuned as well as highlighting\nthe need for future high-pressure crystallography and related single crystal\nmeasurements to understand the mechanism and nature of the intermediate ISDW\nphase to be exploited in future devices."
    },
    {
        "anchor": "Atomically Resolved Spin-Dependent Tunnelling on the Oxygen-Terminated\n  Fe3O4 (111): We employ spin-polarized (SP) STM to study the spin-dependent tunneling\nbetween a magnetite (111) sample and an antiferromagnetic tip through a vacuum\nbarrier at room temperature. Atomic scale STM images show significant magnetic\ncontrast corresponding to variations in the local surface states induced by\noxygen vacancies. The estimated variations in tunneling magnetoresistance (TMR)\nof 250% suggest that the spin-transport properties are significantly altered\nlocally by the presence of surface defects.",
        "positive": "Antiferromagnetic spintronics: Antiferromagnetic materials could represent the future of spintronic\napplications thanks to the numerous interesting features they combine: they are\nrobust against perturbation due to magnetic fields, produce no stray fields,\ndisplay ultrafast dynamics and are capable of generating large\nmagneto-transport effects. Intense research efforts over the past decade have\nbeen invested in unraveling spin transport properties in antiferromagnetic\nmaterials. Whether spin transport can be used to drive the antiferromagnetic\norder and how subsequent variations can be detected are some of the thrilling\nchallenges currently being addressed. Antiferromagnetic spintronics started out\nwith studies on spin transfer, and has undergone a definite revival in the last\nfew years with the publication of pioneering articles on the use of spin-orbit\ninteractions in antiferromagnets. This paradigm shift offers possibilities for\nradically new concepts for spin manipulation in electronics. Central to these\nendeavors are the need for predictive models, relevant disruptive materials and\nnew experimental designs. This paper reviews the most prominent spintronic\neffects described based on theoretical and experimental analysis of\nantiferromagnetic materials. It also details some of the remaining bottlenecks\nand suggests possible avenues for future research."
    },
    {
        "anchor": "Optical absorption in small BN and C nanotubes: We present a theoretical study of the optical absorption spectrum of small\nboron-nitride and carbon nanotubes using time-dependent density-functional\ntheory and the random phase approximation. Both for C and BN tubes, the\nabsorption of light polarized perpendicular to the tube-axis is strongly\nsuppressed due to local field effects. Since BN-tubes are wide band-gap\ninsulators, they only absorb in the ultra-violet energy regime, independently\nof chirality and diameter. In comparison with the spectra of the single C and\nBN-sheets, the tubes display additional fine-structure which stems from the\n(quasi-) one-dimensionality of the tubes and sensitively depends on the\nchirality and tube diameter. This fine structure can provide additional\ninformation for the assignment of tube indices in high resolution optical\nabsorption spectroscopy.",
        "positive": "Voltage equilibration for reactive atomistic simulations of\n  electrochemical processes: We introduce EChemDID, a model to describe electrochemical driving force in\nreactive molecular dynamics simulations. The method describes the equilibration\nof external electrochemical potentials (voltage) within metallic structures and\ntheir effect on the self consistent partial atomic charges used in reactive\nmolecular dynamics. An additional variable assigned to each atom denotes the\nlocal potential in its vicinity and we use fictitious, but computationally\nconvenient, dynamics to describe its equilibration within not-simply connected\nmetallic structures on-the-fly during the molecular dynamics simulation. This\nlocal electrostatic potential is used to dynamically modify the atomic\nelectronegativities used to compute partial atomic changes via charge\nequilibration. Validation tests show that the method provides an accurate\ndescription of the electric fields generated by the applied voltage and the\ndriving force for electrochemical reactions. We demonstrate EChemDID via\nsimulations of the operation of electrochemical metallization cells. The\nsimulations predict the switching of the device between a high-resistance to a\nlow-resistance state as a conductive metallic bridge is formed and resistive\ncurrents that can be compared with experimental measurements. In addition to\napplications in nanoelectronics, EChemDID could be useful to model\nelectrochemical energy conversion devices."
    },
    {
        "anchor": "Simulations of Magnetization Reversal in FM/AFM Bilayers With THz\n  Frequency Pulses: It is widely known that antiferromagnets (AFMs) display a high frequency\nresponse in the terahertz (THz) range, which opens up the possibility for\nultrafast control of their magnetization for next generation data storage and\nprocessing applications. However, because the magnetization of the different\nsublattices cancel, their state is notoriously difficult to read. One way to\novercome this is to couple AFMs to ferromagnets - whose state is trivially read\nvia magneto-resistance sensors. Here we present conditions, using theoretical\nmodelling, that it is possible to switch the magnetization of an AFM/FM bilayer\nusing THz frequency pulses with moderate field amplitude and short durations,\nachievable in experiments. Consistent switching is observed in the phase\ndiagrams for an order of magnitude increase in the interface coupling and a\ntripling in the thickness of the FM layer. We demonstrate a range of reversal\npaths that arise due to the combination of precession in the materials and the\nTHz-induced fields. Our analysis demonstrates that the AFM drives the switching\nand results in a much higher frequency dynamics in the FM due to the exchange\ncoupling at the interface. The switching is shown to be robust over a broad\nrange of temperatures relevant for device applications.",
        "positive": "Evidence for a very low-lying S = 9 excited state of the S = 10 single\n  molecule magnet Mn12-acetate: We present a detailed investigation of the temperature and frequency\ndependence of the anomalous EPR transitions first observed in Mn12-acetate by\nHill et al. [Phys. Rev. Lett. 80, 2453 (1998)]. The most dominant of these\ntransitions manifest themselves as an extra series of EPR absorption peaks for\nspectra obtained with the DC field applied within the hard magnetic plane of a\nsingle crystal sample. Recent studies by Amigo et al. [Phys. Rev. B 65, 172403\n(2002)] have attributed these extra peaks to a strain induced transverse\nquadratic anisotropy which gives rise to distinct Mn12-acetate species, each\nhaving a distinct EPR spectrum; on the basis of these measurements, it has been\nsuggested that this transverse anisotropy is responsible for the tunneling in\nMn12-acetate. Our temperature and frequency dependent measurements demonstrate\nunambiguously that these anomalous EPR absorptions vanish as the temperature\ntends to zero, thereby indicating that they correspond to transitions from an\nexcited state of the molecule. We argue that this low lying excited state\ncorresponds to an S = 9 multiplet having very similar zero-field crystal\nparameters to the S = 10 state, and lying only about 10-15 k_B above the S = 10\n(M_S = +/-9) ground state. These findings also compare favorably with available\nneutron scattering data."
    },
    {
        "anchor": "Silicon spin communication: Recent experimental breakthroughs have demonstrated that the electron spin in\nsilicon can be reliably injected and detected as well as transferred over\ndistances exceeding 1 mm. We propose an on-chip communication paradigm which is\nbased on modulating spin polarization of a constant current in silicon wires.\nWe provide figures of merit for this scheme by studying spin relaxation and\ndrift-diffusion models in silicon.",
        "positive": "A novel crystal polymorph of volborthite, Cu3V2O7(OH)2 2H2O: A new polymorph of volborthite [tricopper(II) divanadium(V) heptaoxide\ndihydroxide dihydrate], Cu3V2O7(OH)2 2H2O, has been discovered in a single\ncrystal prepared by hydrothermal synthesis. X-ray analysis reveals that the\nmonoclinic structure has the space group C2/c at room temperature, which is\ndifferent from that of the previously reported C2/m structure. Both structures\nhave Cu3O6(OH)2 layers composed of edge-sharing CuO4(OH)2 octahedra, with V2O7\npillars and water molecules between the layers. The Cu atoms occupy two and\nthree independent crystallographic sites in the C2/m and C2/c structures,\nrespectively, likely giving rise to different magnetic interactions between\nCuII spins in the kagome lattices embedded in the Cu3O6(OH)2 layers."
    },
    {
        "anchor": "Interface Bonding of Zr1-xAlxN Nanocomposites Investigated by X-ray\n  Spectroscopies and First Principles Calculations: The electronic structure, chemical bonding and interface component in ZrN-AlN\nnanocomposites formed by phase separation during thin film deposition of\nmetastable Zr1-xAlxN (x=0.0, 0.12, 0.26, 0.40) is investigated by resonant\ninelastic X-ray scattering/X-ray emission and X-ray absorption spectroscopy and\ncompared to first-principles calculations including transitions between orbital\nangular momentum final states. The experimental spectra are compared with\ndifferent interface-slab model systems using first-principle all electron\nfull-potential calculations where the core states are treated fully\nrelativistic. As shown in this work, the bulk sensitivity and element\nselectivity of X-ray spectroscopy enables to probe the symmetry and orbital\ndirections at interfaces between cubic and hexagonal crystals. We show how the\nelectronic structure develop from local octahedral bond symmetry of cubic ZrN\nthat distorts for increasing Al content into more complex bonding. This results\nin three different kinds of bonding originating from semi-coherent interfaces\nwith segregated ZrN and lamellar AlN nanocrystalline precipitates. An\nincreasing chemical shift and charge transfer between the elements takes place\nwith increasing Al content and affects the bond strength and increases\nresistivity.",
        "positive": "Electron--phonon interaction without overscreening: a strategy for\n  first--principles modelling: State-of-the-art approaches to calculate the electron-phonon and the\nphonon-electron self-energy are based on a mean-field approximation for the\ninteracting electronic system. This approach introduces an overscreening error\nwhich results in an underestimation of the electron-phonon coupling strength.\nWe introduce a theoretical and numerical approach for the calculation of the\nphonon-electron self-energy without the overscreening error. Starting from the\nout-of-equilibrium Kadanoff-Baym equations for the phonon propagator, we\ndiscuss and compare the overscreened (i.e., symmetrically screened) and\noverscreening--free (i.e., asymmetrically screened) cases. We point out that\nthe difficulty in treating the latter stems from the static approximation to\nthe dielectric function and from the need to obtain a self-energy that\npreserves the elementary scattering processes. We solve both problems in the\nequilibrium case by considering a manifestly symmetric form of the correct\nself-energy which can be easily calculated numerically and yields an\noverscreening--free coupling strength. Finally, we describe the numerical\nimplementation of this treatment into the first--principles Yambo code for the\ncalculations of phonon linewidths."
    },
    {
        "anchor": "Hindered rolling and friction anisotropy in supported carbon nanotubes: Carbon nanotubes (CNTs) are well known for their exceptional thermal,\nmechanical and electrical properties. For many CNT applications it is of the\nforemost importance to know their frictional properties. However, very little\nis known about the frictional forces between an individual nanotube and a\nsubstrate or tip. Here, we present a combined theoretical and experimental\nstudy of the frictional forces encountered by a nanosize tip sliding on top of\na supported multiwall CNT along a direction parallel or transverse to the CNT\naxis. Surprisingly, we find a higher friction coefficient in the transverse\ndirection compared with the parallel direction. This behaviour is explained by\na simulation showing that transverse friction elicits a soft 'hindered rolling'\nof the tube and a frictional dissipation that is absent, or partially absent\nfor chiral CNTs, when the tip slides parallel to the CNT axis. Our findings can\nhelp in developing better strategies for large-scale CNT assembling and sorting\non a surface.",
        "positive": "Effects of aluminum on hydrogen solubility and diffusion in deformed\n  Fe-Mn alloys: We discuss hydrogen diffusion and solubility in aluminum alloyed Fe-Mn\nalloys. The systems of interest are subjected to tetragonal and isotropic\ndeformations. Based on ab initio modelling, we calculate solution energies,\nthen employ Oriani's theory which reflects the influence of Al alloying via\ntrap site diffusion. This local equilibrium model is complemented by\nqualitative considerations of Einstein diffusion. Therefore, we apply the\nclimbing image nudged elastic band method to compute the minimum energy paths\nand energy barriers for hydrogen diffusion. Both for diffusivity and solubility\nof hydrogen, we find that the influence of the substitutional Al atom has both\nlocal chemical and nonlocal volumetric contributions."
    },
    {
        "anchor": "Towards Air Stability of Ultra-Thin GaSe Devices: Avoiding Environmental\n  and Laser-Induced Degradation by Encapsulation: Gallium selenide (GaSe) is a novel two-dimensional material, which belongs to\nthe layered III-VIA semiconductors family and attracted interest recently as it\ndisplays single-photon emitters at room temperature and strong optical\nnon-linearity. Nonetheless, few-layer GaSe is not stable under ambient\nconditions and it tends to degrade over time. Here we combine atomic force\nmicroscopy, Raman spectroscopy and optoelectronic measurements in\nphotodetectors based on thin GaSe to study its long-term stability. We found\nthat the GaSe flakes exposed to air tend to decompose forming firstly amorphous\nselenium and Ga2Se3 and subsequently Ga2O3. While the first stage is\naccompanied by an increase in photocurrent, in the second stage we observe a\ndecrease in photocurrent which leads to the final failure of GaSe\nphotodetectors. Additionally, we found that the encapsulation of the GaSe\nphotodetectors with hexagonal boron nitride (h-BN) can protect the GaSe from\ndegradation and can help to achieve long-term stability of the devices.",
        "positive": "Composition and temperature dependence of the thermoelectric power of\n  Ni$_{2+x}$Mn$_{1-x}$Ga alloys: The thermoelectric power (TEP) measurements have been carried out to\ninvestigate the changes in the electronic structure associated with the\nintermartensitic and martensitic transitions in Ni$_{2+x}$Mn$_{1-x}$Ga (0 $\\le$\nx $\\le$ 0.19). The samples have been characterized by a.c. magnetic\nsusceptibility measurements. The correlation between the TEP and the\nmicrostructural changes sensitive to the increasing Ni content in\nNi$_{2+x}$Mn$_{1-x}$Ga has been investigated. The changes in the density of\nstates as reflected in the temperature variation of the TEP are consistent with\nthe conclusions drawn from the Jahn-Teller mechanism of lattice distortion."
    },
    {
        "anchor": "Decoupling bulk and surface recombination properties in silicon by\n  depth-dependent carrier lifetime measurements: Muons, as a bulk probe of materials, have been used to study the depth\nprofile of charge carrier kinetics in Si wafers by scanning the muon\nimplantation depth. The photoexcited muon spin spectroscopy technique can\noptically generate excess carriers in semiconductor wafers, while muons can\nmeasure the excess carrier density. As a result, carrier recombination lifetime\nspectra can be obtained. The depth-dependent lifetime spectra enable us to\naccurately measure the bulk carrier lifetime and surface recombination velocity\nby fitting the spectra to a simple 1-dimensional diffusion model. Unlike other\ntraditional lifetime spectroscopy techniques, the bulk and surface\nrecombination properties can be readily de-convoluted in this method. Here, we\nhave applied the technique to study silicon wafers both with and without\npassivation treatment, and have demonstrated that the model can correctly\ndescribe the carrier kinetics in these two cases.",
        "positive": "Periodic ripples on thermally annealed Graphene on Cu (110) - Surface\n  reconstruction or Moire pattern?: We have used Ultrahigh Vacuum (UHV) Scanning tunneling microscopy (STM) to\ninvestigate the effect of thermal annealing of graphene grown by chemical\nvapour deposition (CVD) on a Cu(110) foil. We show that the annealing appears\nto induce a reconstruction of the Cu surface along the [210] direction, with a\nperiod of 1.43 nm. Such reconstructions have been ascribed to the tensile\nstrain induced in the Cu surface by differential thermal expansion of it\nrelative to the graphene overlayer, but we show that it is in fact a Moir\\'e\npattern due to interference between the graphene and the underlying atomic\nlattice as evidenced by the appearance of an odd-even transition only observed\ndue to mis-orientation of the top layer of a crystal. This highlights that the\nanalysis of STM measurements of graphene on metal surfaces should take such\ninterference into account and that the graphene-Cu interface is more complex\nthan previously thought."
    },
    {
        "anchor": "Li-decorated BC3 nanopores: Promising materials for hydrogen storage: In the quest of new absorbent for hydrogen storage, we investigate the\ncapacities of slit pores formed by two BC3 sheets decorated with Li atoms.\nTheir hydrogen storage capacities are determined using density-functional\ntheory in conjunction with a quantum-thermodynamic model that allows to\nsimulate real operating conditions, i.e., finite temperatures and different\nloading and depletion pressures applied to the adsorbent in the charge-delivery\ncycles. We show that the capacities of the adsorbed hydrogen phase of\nLi-decorated BC3 slit pores are larger than those reported recently for\ngraphene and Li-decorated borophene slit pores. On the other hand, the usable\nvolumetric and gravimetric capacities of Li-decorated BC3 slit pores can meet\nthe targets stipulated by the U.S. Department of Energy (DOE) for onboard\nhydrogen storage at moderate temperatures and loading pressures well below\nthose used in the tanks employed in current technology. In particular, the\nusable volumetric capacity for pore widths of about 10 {\\AA} meets the DOE\ntarget at a loading pressure of 6.6 MPa when depleting at ambient pressure. Our\nresults highlight the important role played by the rotational degree of freedom\nof the H2 molecule in determining the confining potential within the slip pores\nand their hydrogen storage capacities.",
        "positive": "The nano-structural inhomogeneity of dynamic hydrogen bond network of\n  water: In the present study, water is considered as a dynamic network between\nmolecules at distances not exceeding 3.2 angstroms. The instantaneous\nconfigurations obtained by using the molecular dynamics method have been\nsequentially analyzed, the mutual orientation of each molecule with its\nneighboring molecules has been studied and the interaction energy of each pair\nof neighbor molecules has been calculated. The majority of mutual orientation\nangles between molecules lie in the interval [10, 30] degrees. It has been\nshown that more than 85% of the molecular pairs in each instantaneous\nconfiguration form H-bonds and the H-bond network includes all water molecules\nin the temperature range 233-293 K. The number of H-bonds fluctuates near the\nmean value and increases with decreasing temperature, and the energy of the\nvast majority of such bonds is much higher than the thermal energy. The\ninteraction energy of 80% of the H-bonding molecular pairs lies in the interval\n[-7; -4] kcal/mol. The interaction energy of pairs that do not satisfy the\nH-bond angle criterion lies in the interval [-5; 4] kcal/mol, and the number of\nsuch bonds does not exceed 15% and decreases with decreasing temperature. For\nthe first time it was found that in each instantaneous configuration the H-bond\nnetwork contains built-in nanometric structural heterogeneities formed by\nshorter H-bonds. The fraction of molecules involved in the structural\nheterogeneities increases from 40% to 60% with a temperature decrease from 293\nK to 233 K. These heterogeneities have a finite lifetime, but are constantly\npresent in the water. The number of large heterogeneities (containing more than\n20 molecules) increases with decreasing temperature, and the number of small\nstructural heterogeneities (less than 20) decreases."
    },
    {
        "anchor": "Influences of Granular Constraints and Surface Effects on the\n  Heterogeneity of Elastic, Superelastic, and Plastic Responses of\n  Polycrystalline Shape Memory Alloys: Deformation heterogeneities within microstructures of polycrystalline shape\nmemory alloys (SMAs) during superelastic stressing are studied using both\nexperiments and simulations. In situ X-ray diffraction, specifically the\nfar-field high energy diffraction microscopy (ff-HEDM) technique was used to\nnon-destructively measure the grain-averaged statistics of position, crystal\norientation, elastic strain tensor and volume for hundreds of austenite grains\nin a superelastically loaded nickel-titanium (NiTi) SMA. This experimental data\nwere also used to create a synthetic microstructure within a finite element\nmodel. The development of intragranular stresses were then simulated during\ntensile loading of the model using anisotropic elasticity. Driving forces for\nphase transformation and slip were calculated from these stresses. The\ngrain-average responses of individual austenite crystals examined before and\nafter multiple stress-induced transformation events showed that grains at the\nspecimen interior carry more stress and plastically deform less than the\nsurface grains as the superelastic response shakes down. Examination of the\nheterogeneity within individual grains showed that regions near grain\nboundaries exhibit larger stress variation compared to the grain interiors.\nThis intragranular heterogeneity is more strongly driven by the constraints of\nneighboring grains than the initial stress state and orientation of the\nindividual grains.",
        "positive": "Pbca-type In2O3: the lost pressure-induced post-corundum phase: Contradictory results of high-pressure studies in cubic bixbyite-type indium\noxide (c-In2O3) at room temperature (RT) have motivated us to perform\nhigh-pressure powder x-ray diffraction and Raman scattering measurements in\nthis material. On increasing pressure c-In2O3 undergoes a transition to the\nRh2O3-II structure. On decreasing pressure Rh2O3-II-type In2O3 undergoes a\ntransition to a previously unknown phase which is isostructural to Rh2O3-III.\nOn further decrease of pressure, another phase transition to corundum-type\nIn2O3, which is metastable at room conditions, is observed. Recompression of\nmetastable corundum-type In2O3 shows that the Rh2O3-III phase is the\npost-corundum phase. Our results are supported by theoretical ab initio\ncalculations which show that the Rh2O3-III phase could be present in other\nsesquioxides, thus leading to a revision of the pressure-temperature phase\ndiagrams of sesquioxides."
    },
    {
        "anchor": "Towards a frequency independent incremental ab initio scheme for the\n  self energy: The frequency dependence of the self energy of a general many--body problem\nis identified as a main obstacle in correlation calculations based on local\napproaches. A frequency independent formulation is proposed instead and proven\nto yield exactly the same numerical results as the original common scheme. Our\napproach is embedded in a general local-orbital based ab initio frame to obtain\nthe Green's function for large heterogenous systems. First a Green's function\nformalism is introduced. Then the self energy is constructed from an\nincremental scheme. Subsequently we apply the proposed frequency independent\nformulation. The theory is applied to para-ditholbenzene as a realistic system\nand the numerical accuracy of the correlation contributions obtained from our\nfrequency independent access are carefully tested against the exact frequency\ndependent results. Perfect agreement is reached and a speed--up of a factor 50\nis established for the incremental scheme.",
        "positive": "Calculation of Release Adiabats and Shock Impedance Matching: In the analysis of impedance-match experiments, the release adiabat of the\nstandard material is often approximated by reflecting the Hugoniot in the\npressure-particle velocity (P-UP) plane. In cases where it has been tested\nexperimentally, this reflected shock approximation (RSA) has been found to be\nfairly accurate at pressures as high as 100 GPa. The success of the RSA is\nusually attributed to the lack of thermal effects, i.e., that the Hugoniot and\nrelease adiabat are nearly identical in the pressure-density (P-rho) plane.\nThis report demonstrates that this explanation is not correct. The success of\nthe RSA does not arise from the absence of thermal effects--it arises because\nof thermal effects. When the Hugoniot and adiabat are identical in the P-rho\nplane, the adiabat lies below the reflected Hugoniot when mapped into the P-UP\nplane. Material strength effects also cause the exact adiabat to lie below the\nRSA. A thermal offset between the Hugoniot and the adiabat compensates for\nthese two effects, so that the RSA turns out to give good results for many\nmaterials, even at high pressures. However, this fortuitous cancellation of\nerrors does not occur in all cases. This report shows that the RSA is not\naccurate for two \"soft\" materials, Teflon and PMMA, and for a high-strength\nmaterial, tungsten. The issues discussed here apply to use of the RSA at low\npressures, not to very high pressures, where it is already well-known to be\ninaccurate."
    },
    {
        "anchor": "Dissipation-induced symmetry breaking: Emphanitic transitions in lead-\n  and tin-containing chalcogenides and halide perovskites: Lead and tin-based chalcogenide semiconductors like PbTe or SnSe have long\nbeen known to exhibit an unusually low thermal conductivity that makes them\nvery attractive thermoelectric materials. An apparently unrelated fact is that\nthe excitonic bandgap in these materials increases with temperature, whereas\nfor most semiconductors one observes the opposite trend. These two anomalous\nfeatures are also seen in a very different class of photovoltaic materials,\nnamely the halide-perovskites such as CsPbBr3. It has been previously proposed\nthat emphanisis, a local symmetry-breaking phenomenon, is the one common origin\nof these unusual features. Discovered a decade ago, emphanisis is the name\ngiven to the observed displacement of the lead or the tin ions from their cubic\nsymmetry ground state to a locally distorted phase at high temperature. This\nphenomenon has been puzzling because it is unusual for the high-temperature\nstate to be of a lower symmetry than the degenerate ground state. Motivated by\nthe celebrated vibration-inversion resonance of the ammonia molecule, we\npropose a quantum tunneling-based model for emphanisis where decoherence is\nresponsible for the local symmetry breaking with increasing temperature. From\nthe analytic expression of the temperature dependence of the tunnel splitting\n(which serves as an order parameter), we provide three-parameter fitting\nformulae which capture the observed temperature dependence of the ionic\ndisplacements as well as the anomalous increase of the excitonic bandgap in all\nthe relevant materials.",
        "positive": "Application of Thomas-Fermi model to fullerene molecule and nanotube: Semiclassical description, based on electrostatics and Thomas-Fermi model is\napplied here to calculate dimensions of the electronic shell of a fullerene\nmolecule and a nanotube. The internal radius of the electronic shell of a\nfullerene molecule, calculated within the framework of the model is 0.2808 nm.\nThe external radius is 0.4182 nm. The experimental values are 0.279 nm and\n0.429 nm correspondingly. This shows that semiclassical approach provides\nrather good description of the dimensions of the electronic shell in a\nfullerene molecule. Two types of dipole oscillations in a fullerene molecule\nare considered and their frequencies are calculated. Similar calculations are\nperformed for a nanotube also. For a nanotube with a radius of the cylinder of\nthe ions, Rn = 0.7 nm, the internal radius of the electronic shell, calculated\nwithin the framework of the model is 0.577 nm. The external radius is 0.816 nm.\nThree types of dipole oscillations in nanotube are considered and their\nfrequencies are calculated."
    },
    {
        "anchor": "The Effect of Chemical Disorder on Defect Formation and Migration in\n  Disordered MAX Phases: MAX phases have attracted increased attention due to their unique combination\nof ceramic and metallic properties. Point-defects are known to play a vital\nrole in the structural, electronic and transport properties of alloys in\ngeneral and this system in particular. As some MAX phases have been shown to be\nstable in non-stoichiometric compositions, it is likely that such alloying\neffects will affect the behavior of lattice point defects. This problem,\nhowever, remains relatively unexplored. In this work, we investigate the\nalloying effect on the structural-stability, energy-stability,\nelectronic-structure, and diffusion barrier of point defects in MAX phase\nalloys within a first-principles density functional theory framework. The\nvacancy (V$_{M}$, V$_{A}$, V$_{X}$) and antisite (M-A; M-X) defects are\nconsidered with M and A site disorder in (Zr-M)$_{2}$(AA${'}$)C, where\nM=Cr,Nb,Ti and AA${'}$=Al, Al-Sn, Pb-Bi. Our calculations suggest that the\nchemical disorder helps lower the V$_{A}$ formation energies compared to\nV$_{M}$ and V$_{X}$. The V$_{A}$ diffusion barrier is also significantly\nreduced for M-site disorder compared to their ordered counterpart. This is very\nimportant finding because reduced barrier height will ease the Al diffusion at\nhigh-operating temperatures, which will help the formation of passivating oxide\nlayer (i.e., Al$_{2}$O$_{3}$ in aluminum-based MAX phases) and will slow down\nor stop the material degradation. We believe that our study will provide a\nfundamental understanding and an approach to tailor the key properties that can\nlead to the discovery of new MAX phases.",
        "positive": "Silicane and germanane: tight-binding and first-principles studies: We present a first-principles and tight-binding model study of silicane and\ngermanane, the hydrogenated derivatives of two-dimensional silicene and\ngermanene. We find that the materials are stable in freestanding form, analyse\nthe orbital composition, and derive a tight-binding model using\nfirst-principles calculations to fit the parameters."
    },
    {
        "anchor": "Doping and Field-Induced Insulator-Metal Transitions in Half-Doped\n  Manganites: We argue that many properties of the half-doped manganites may be understood\nin terms of a new two-(eg electron)-fluid description, which is energetically\nfavorable at intermediate Jahn-Teller (JT) coupling. This emerges from a\ncompetition between canting of the core spins of Mn promoting mobile carriers\nand polaronic trapping of carriers by JT defects, in the presence of CE,\norbital and charge order. We show that this explains several features of the\ndoping and magnetic field induced insulator-metal transitions, as the\nparticle-hole asymmetry and the smallness of the transition fields.",
        "positive": "Acceptor and compensating donor doping of single crystalline SnO (001)\n  films grown by molecular beam epitaxy and its perspectives for\n  optoelectronics and gas-sensing: (La and Ga)-doped tin monoxide (stannous oxide, tin (II) oxide, SnO) thin\nfilms were grown by plasma-assisted and suboxide molecular beam epitaxy with\ndopant concentrations ranging from $\\approx5\\times10^{18}$cm$^{-3}$ to\n$2\\times10^{21}$cm$^{-3}$. In this concentration range, the incorporation of Ga\ninto SnO was limited by the formation of secondary phases observed at\n$1.2\\times10^{21}$cm$^{-3}$ Ga, while the incorporation of La showed a lower\nsolubility limit. Transport measurements on the doped samples reveal that Ga\nacts as an acceptor and La as a compensating donor. While Ga doping led to an\nincrease of the hole concentration from\n$1\\times10^{18}$cm$^{-3}-1\\times10^{19}$cm$^{-3}$ for unintentionally (UID) SnO\nup to $5\\times10^{19}$cm$^{-3}$, La-concentrations well in excess of the UID\nacceptor concentration resulted in semi-insulating films without detectable\n$n$-type conductivity. Ab-initio calculations qualitatively agree with our\ndopant assignment of Ga and La, and further predict In$_\\text{Sn}$ to act as an\nacceptor as well as Al$_\\text{Sn}$ and B$_\\text{Sn}$ as donor. These results\nshow the possibilities of controlling the hole concentration in $p$-type SnO,\nwhich can be useful for a range of optoelectronic and gas-sensing applications."
    },
    {
        "anchor": "Polarization Symmetry Breaking in Nitrogen under High Pressure: An order parameter with broken polarization symmetry is proposed for the\npressure-induced molecular dissociation transitions in nitrogen. The\nexperimental dissociative transition pressure dependence of the calculated\norder parameter is well described by a power law of the form P=kq2. Our results\nunveil the important role of symmetry breaking in nitrogen under high pressure\nand further demonstrate a path from dense molecular fluid to fully polymeric\nphases by breaking local polarization reversal symmetry.",
        "positive": "A mesoscale granular model for the mechanical behavior of alloys during\n  solidification: We present a two-dimensional granular model for the mechanical behavior of an\nensemble of globular grains, during solidification. The grain structure is\nproduced by a Voronoi tessellation based on an array of predefined nuclei. We\nconsider the fluid flow caused by grain movement and solidification shrinkage\nin the network of channels that is formed by the faces of the grains in the\ntessellation. We develop the governing equations for the flow rate and pressure\ndrop across each channel when the grains are allowed to move, and we then\nassemble the equations into a global expression that conserves mass and force\nin the system. We show that the formulation is consistent with dissipative\nformulations of non-equilibrium thermodynamics. Several example problems are\npresented to illustrate the effect of tensile strains and the availability of\nliquid to feed the deforming microstructure. For solid fractions below gs=0.97,\nwe find that the fluid is able to feed the deformation at low strain, even if\nexternal feeding is not permitted. For solid fractions above gs=0.97, clusters\nof grains with \"dry\" boundaries form, and fluid flow becomes highly localized."
    },
    {
        "anchor": "Effect of Composition on Microstructural Evolution during Homogenization\n  of 7XXX Alloys: The effect of composition on microstructure both at the length scale of the\nsecondary dendrite arm spacing and nano-sized dispersoids during homogenization\nof Al-Zn-Cu-Mg-Zr alloys has been studied. A comprehensive model that can\npredict the microstructure at both the length scales has been used for the\nstudy. The microstructure predicted has been compared to that for two\nhomogenized samples from a directionally solidified AA7050 sample and a\nreasonable match has been found. The initial as-cast microstructure for\ndifferent compositions is calculated using Scheil type solidification from\nThermo-Calc. The initial microstructure has a considerable influence on\nmicrostructural evolution during homogenization. To take advantage of the\ndecreased solid solubility of Zr in {\\alpha}-fcc, cooling rates during\nsolidification must be high enough to prevent precipitation of primary Al3Zr.\nUnder solidification with industrial cooling conditions solute rich alloys\nleads to fewer dispersoids. Based on the study, an improved composition range\nof 6-8%Zn, 1-2%Cu, 1-2%Mg and 0.1-0.15%Zr for 7XXX alloys has been proposed.",
        "positive": "Electromechanical dopant defect interaction in acceptor doped ceria: Oxygen defective cerium oxides exhibits a non classical giant\nelectromechanical response that is superior to lead based electrostrictors. In\nthis work, we report the key role of acceptor dopants, with different size and\nvalence Mg2+, Sc3+, Gd3+, and La3+, on polycrystalline bulk ceria. Different\ndopants tune the electrostrictive properties by changing the electrosteric\ndopant defect interactions. We find two distinct electromechanical behaviors\nwhen the interaction is weak dopant vacancy binding energy 0.3 eV,\nelectrostriction displays high coefficient, up to 10-17 m2V-2, with strongly\ntime dependent effects. In contrast, we observe no time dependent effects when\nthe interaction becomes strong 0.6 eV."
    },
    {
        "anchor": "Specific Heat Anomalies in Solids Described by a Multilevel Model: Specific heat measurements constitute one of the most powerful experimental\nmethods to probe fundamental excitations in solids. After the proposition of\nEinstein's model, more than one century ago (Annalen der Physik \\textbf{22},\n180 (1907)), several theoretical models have been proposed to describe\nexperimental results. Here we report on a detailed analysis of the two-peak\nspecific heat anomalies observed in several materials. Employing a simple\nmultilevel model, varying the spacing between the energy levels $\\Delta_i$ =\n$(E_i$ $-$ $E_{0})$ and the degeneracy of each energy level $g_i$, we derive\nthe required conditions for the appearance of such anomalies. Our findings\nindicate that a ratio of $\\Delta_2$/$\\Delta_1$ $\\thickapprox$ 10 between the\nenergy levels and a high degeneracy of one of the energy levels define the\ntwo-peaks regime in the specific heat. Our approach accurately matches recent\nexperimental results. Furthermore, using a mean-field approach we calculate the\nspecific heat of a degenerate Schottky-like system undergoing a ferromagnetic\n(FM) phase transition. Our results reveal that as the degeneracy is increased\nthe Schottky maximum in the specific heat becomes narrow while the peak\nassociated with the FM transition remains unaffected.",
        "positive": "Towards fully automatized GW band structure calculations: What we can\n  learn from 60.000 self-energy evaluations: We analyze a data set comprising 370 GW band structures composed of 61716\nquasiparticle (QP) energies of two-dimensional (2D) materials spanning 14\ncrystal structures and 52 elements. The data results from PAW plane wave based\none-shot G$_0$W$_0$@PBE calculations with full frequency integration. We\ninvestigate the distribution of key quantities like the QP self-energy\ncorrections and renormalization factor $Z$ and explore their dependence on\nchemical composition and magnetic state. The linear QP approximation is\nidentified as a significant error source and propose schemes for controlling\nand drastically reducing this error at low computational cost. We analyze the\nreliability of the $1/N_\\text{PW}$ basis set extrapolation and find that is\nwell-founded with narrow distributions of $r^2$ peaked very close to 1.\nFinally, we explore the validity of the scissors operator approximation\nconcluding that it is generally not valid for reasonable error tolerances. Our\nwork represents a step towards the development of automatized workflows for\nhigh-throughput G$_0$W$_0$ band structure calculations for solids."
    },
    {
        "anchor": "Formation and magnetic properties of spark plasma sintered\n  Mn$_{3-\u03b4}$ ($\u03b4$ = 0, 1) alloys: We present the synthesis of D0$_{22}$ Mn$_{3 - \\delta}$Ga ($\\delta$ = 0, 1)\nHeusler alloys by Spark Plasma Sintering method. The single phase Mn$_3$Ga\n(T$_\\mathrm{c}$ $\\simeq$ 780 K) is synthesized, while Mn$_2$Ga (T$_\\mathrm{c}$\n$\\simeq$ 710 K) is found to coexist with a near-stoichiometric room temperature\nparamagnetic Mn$_9$Ga$_5$~($\\approx$ 15 \\%) phase due to its lower formation\nenergy, as confirmed from our density functional theory (DFT) calculations. The\nalloys show hard magnetic behavior with large room temperature spontaneous\nmagnetization m$_s$(80 kOe) = 1.63 (0.83) $\\mu_\\mathrm{B}$/f.u. and coercivity\nH$_\\mathrm{c}$ = 4.28 (3.35) kOe for Mn$_3$Ga (Mn$_2$Ga). The magnetic\nproperties are further investigated till T$_\\mathrm{c}$ and the H$_\\mathrm{c}$\n(T) analysis by Stoner-Wohlfarth model shows the nucleation mechanism for the\nmagnetization reversal. The experimental results are well supported by DFT\ncalculations, which reveal that the ground state of D0$_{22}$ Mn$_2$Ga is\nachieved by the removal of Mn-atoms from full Heusler Mn$_3$Ga structure in\naccordance with half Heusler alloy picture.",
        "positive": "Critical assessment of machine-learned repulsive potentials for the\n  Density Functional based Tight-Binding method: a case study for pure silicon: We investigate the feasability of improving the semi-empirical density\nfunctional based tight-binding method (DFTB) through a general and transferable\nmany-body repulsive potential for pure silicon using a common machine-learning\nframework. Atomic environments using atom centered symmetry functions fed into\nflexible high-dimensional neural-networks allow to overcome the limited pair\npotentials used until now, with the ability to train simultaneously on a large\nvariety of systems. We achieve an improvement on bulk systems, with good\nperformance on energetic, vibrational and structural properties. Contrarily,\nthere are difficulties for clusters due to surface effects. To deepen the\ndiscussion, we also put these results into perspective with two fully\nmachine-learned numerical potentials for silicon from the literature. This\nallows us to identify both the transferability of such approaches together with\nthe impact of narrowing the role of machine-learning models to reproduce only a\npart of the total energy."
    },
    {
        "anchor": "Evolutionary Search and Theoretical Study of Silicene Grain Boundaries'\n  Mechanical Properties: Defects such as grain boundaries (GBs) are almost inevitable during the\nsynthesis process of 2D materials. To take advantage of the fascinating\nproperties of 2D materials, understanding the nature and impact of various GB\nstructures on the pristine 2D sheet is crucial. In this work, using an\nevolutionary algorithm search, we predict a wide variety of silicene GB\nstructures with very different atomic structures compared to those found in\ngraphene or hexagonal boron-nitride. Twenty-one GBs with the lowest energy were\nvalidated by density functional theory (DFT) - a majority of which were\npreviously unreported to our best knowledge. Based on the diversity of the GB\npredictions, we found that the formation energy and mechanical properties can\nbe dramatically altered by adatoms positions within a GB and certain types of\natomic structures, such as four-atom rings. To study the mechanical behavior of\nthese GBs, we apply strain to the GB structures stepwise and use DFT\ncalculations to investigate the mechanical properties of 9 representative\nstructures. It is observed that GB structures based on pentagon-heptagon pairs\nare likely to have similar or higher in-plane stiffness and strength compared\nwith the zigzag orientation of pristine silicene. However, an adatom located at\nthe hollow site of a heptagon ring can significantly deteriorate the mechanical\nstrength. For all the structures, the in-plane stiffness and strength were\nfound to decrease with increasing formation energy. For the failure behavior of\nGB structures, it was found that GB structures based on pentagon-heptagon pairs\nhave failure behavior similar to graphene. We also found that the GB structures\nwith atoms positioned outside of the 2D plane tend to experience phase\ntransitions before failure. Utilizing the evolutionary algorithm, we locate\ndiverse silicene GBs and obtain useful information for their mechanical\nproperties.",
        "positive": "A route towards finding large magnetic anisotropy in nano-composites:\n  application to a W$_{1-x}$Re$_x$/Fe multilayer: We suggest here a novel nano-laminate, 5[Fe]/2[W$_x$Re$_{1-x}$] (x=0.6-0.8),\nwith enhanced magnetic hardness in combination with a large saturation moment.\nThe calculated magnetic anisotropy of this material reaches values of 5.3-7.0\nMJ/m$^3$, depending on alloying conditions. We also propose a recipe in how to\nidentify other novel magnetic materials, such as nano-laminates and\nmultilayers, with large magnetic anisotropy in combination with a high\nsaturation moment."
    },
    {
        "anchor": "Formation of double ring patterns on Co2MnSi Heusler alloy thin film by\n  anodic oxidation under scanning probe microscope: Double ring formation on Co2MnSi (CMS) films is observed at electrical\nbreakdown voltage during local anodic oxidation (LAO) using atomic force\nmicroscope (AFM). Corona effect and segregation of cobalt in the vicinity of\nthe rings is studied using magnetic force microscopy and energy dispersive\nspectroscopy. Double ring forma-tion is attributed to the interaction of\nablated material with the induced magnetic field during LAO. Steepness of\nforward bias transport characteristics from the unperturbed region of the CMS\nfilm suggest a non equilibrium spin contribution. Such mesoscopic textures in\nmagnetic films by AFM tip can be potentially used for memory storage\napplications.",
        "positive": "Physics-Informed Machine Learning and Uncertainty Quantification for\n  Mechanics of Heterogeneous Materials: In this work, a model based on the Physics - Informed Neural Networks (PINNs)\nfor solving elastic deformation of heterogeneous solids and associated\nUncertainty Quantification (UQ) is presented. For the present study, the PINNs\nframework - Modulus developed by Nvidia is utilized, wherein we implement a\nmodule for mechanics of heterogeneous solids. We use PINNs to approximate\nmomentum balance by assuming isotropic linear elastic constitutive behavior\nagainst a loss function. Along with governing equations, the associated initial\n/ boundary conditions also softly participate in the loss function. Solids\nwhere the heterogeneity manifests as voids (low elastic modulus regions) and\nfibers (high elastic modulus regions) in a matrix are analyzed, and the results\nare validated against solutions obtained from a commercial Finite Element (FE)\nanalysis package. The present study also reveals that PINNs can capture the\nstress jumps precisely at the material interfaces. Additionally, the present\nstudy explores the advantages associated with the surrogate features in PINNs\nvia the variation in geometry and material properties. The presented UQ studies\nsuggest that the mean and standard deviation of the PINNs solution are in good\nagreement with Monte Carlo FE results. The effective Young's modulus predicted\nby PINNs for single representative void and single fiber composites compare\nvery well against the ones predicted by FE, which establishes the PINNs\nformulation as an efficient homogenization tool."
    },
    {
        "anchor": "Unusual magnetism of layered chromium sulfides MCrS2 (M=Li, Na, K, Ag,\n  and Au): MCrS2 compounds (M=Li, Na, K, Cu, Ag, and Au) with triangular Cr layers show\nlarge variety of magnetic ground states ranging from 120-degree\nantiferromagnetic order of Cr spins in LiCrS2 to double stripes in AgCrS2,\nhelimagnetic order in NaCrS2, and, finally, ferromagnetic Cr layers in KCrS2.\nOn the base of ab-initio band structure calculations and an analysis of various\ncontributions to exchange interactions between Cr spins we explain this\ntendency as originating from a competition between antiferromagnetic direct\nnearest-neighbor d-d exchange and ferromagnetic superexchange via S p states\nwhich leads to the change of the sign of the nearest neighbor interaction\ndepending on the radius of a M ion. It is shown that other important\ninteractions are the third-neighbor interaction in a layer and interlayer\nexchange. We suggest that strong magneto-elastic coupling is most probably\nresponsible for multiferroic properties of at least one material of this\nfamily, namely, AgCrS2.",
        "positive": "Electron-lattice interaction and structural stability of the oxy-borate\n  Co3O2BO3: A theoretical study is carried out in the homometallic mixed valent ludwigite\nCo3O2BO3 using a modified tight binding methodology. The study focuses on the\nelectronic properties of bulk, 1D and molecular units to describe differences\nbetween Co3O2BO3 and another homometallic ludwigite, Fe3O2BO3. The latter is\nknown to present a structural instability which has not been found in Co3O2BO3.\nOur results show that bulk band structures present no significant differences.\nDifferences are found in the calculation of 1D stripes formed by 3+ 2+ 3+\ntriads, owed to different 3d occupancy of Fe and Co cations. Conditions for 1D\nsemiconducting transport observed in Fe3O2BO3 are not present in Co3O2BO3. More\nimportant differences were found to be related to local octahedral geometry.\nLarger distortions in Co3O2BO3 lead to higher 2+ 3+ hopping barriers in the\ntriads and consequent localization of charge. In Fe3O2BO3, site equivalence\nprovides easy paths for inter-cation hopping. The present results indicate that\nlocal geometry of the cation sites is the main cause of differences in these\ntwo compounds; dimerization in the triads, which characterizes the structural\nchange in Fe3O2BO3, could be structurally hindered in Co3O2BO3. An analogy is\nmade with two mixed-valent warwickites, Fe2OBO3 and Mn2OBO3, which show the\nsame structural stability/site equivalence relationship."
    },
    {
        "anchor": "Ion transport study of mechanically-milled amorphous AgI-Ag2O-V2O5 fast\n  ionic conductors: The structural and electrical characterizations of mechanically-milled (MM)\namorphous fast ionic conductors (a-FICs), viz. xAgI (100-x)[0.67 Ag\\_2\nO-0.33V\\_2O\\_5] (x = 40, 50, 55 and 70) have been reported. The amorphisation\nis restricted only to the compositions which are well within the glass forming\nregion and all samples are found to be highly agglomerated and X-ray amorphous\nin nature. The frequency dependent ac conductivity, \\sigma'(\\omega), of the\namorphous samples investigated in the frequency range 5Hz -13 MHz and\ntemperature range 100- 350 K shows a dc conductivity regime at low frequencies\nand a dispersive regime at higher frequencies. The spectra can be described by\nthe Jonscher power law (JPL), \\simga'(\\omega) = \\sigma\\_dc +A(T) \\omega\\_n.\nHowever, the values \\sigma\\_dc (T) and A(T) both show two distinct Arrhenius\nregions and n (< 1) is found to be temperature dependent, i.e., decreasing with\nincreasing temperature.",
        "positive": "Optical spectroscopy of excited exciton states in MoS2 monolayers in van\n  der Waals heterostructures: The optical properties of MoS2 monolayers are dominated by excitons, but for\nspectrally broad optical transitions in monolayers exfoliated directly onto\nSiO2 substrates detailed information on excited exciton states is inaccessible.\nEncapsulation in hexagonal boron nitride (hBN) allows approaching the\nhomogenous exciton linewidth, but interferences in the van der Waals\nheterostructures make direct comparison between transitions in optical spectra\nwith different oscillator strength more challenging. Here we reveal in\nreflectivity and in photoluminescence excitation spectroscopy the presence of\nexcited states of the A-exciton in MoS2 monolayers encapsulated in hBN layers\nof calibrated thickness, allowing to extrapolate an exciton binding energy of\nabout 220 meV. We theoretically reproduce the energy separations and oscillator\nstrengths measured in reflectivity by combining the exciton resonances\ncalculated for a screened two-dimensional Coulomb potential with transfer\nmatrix calculations of the reflectivity for the van der Waals structure. Our\nanalysis shows a very different evolution of the exciton oscillator strength\nwith principal quantum number for the screened Coulomb potential as compared to\nthe ideal two-dimensional hydrogen model."
    },
    {
        "anchor": "Narrow-band anisotropic electronic structure of ReS$_2$: We have used angle resolved photoemission spectroscopy to investigate the\nband structure of ReS$_2$, a transition-metal dichalcogenide semiconductor with\na distorted 1T crystal structure. We find a large number of narrow valence\nbands, which we attribute to the combined influence of the structural\ndistortion and spin-orbit coupling. We further image how this leads to a strong\nin-plane anisotropy of the electronic structure, with quasi-one-dimensional\nbands reflecting predominant hopping along zig-zag Re chains. We find that this\ndoes not persist up to the top of the valence band, where a more\nthree-dimensional character is recovered with the fundamental band gap located\naway from the Brillouin zone centre along $k_z$. These experiments are in good\nagreement with our density-functional theory calculations, shedding new light\non the bulk electronic structure of ReS$_2$, and how it can be expected to\nevolve when thinned to a single layer.",
        "positive": "Carrier emission of n-type Gallium Nitride illuminated by femtosecond\n  laser pulses: The carrier emission efficiency of light emitting diodes is of fundamental\nimportance for many technological applications, including the performance of\nGaN and other semiconductor photocathodes. We have measured the evolution of\nthe emitted carriers and the associated transient electric field after\nfemtosecond laser excitation of n-type GaN single crystals. These processes\nwere studied using subpicosecond, ultrashort, electron pulses and explained by\nmeans of a three-layer analytical model. We find that for pump laser\nintensities on the order of 10^11 W/cm^2, the electrons that escaped from the\ncrystal surface have a charge of about 2.7 pc and a velocity of about 1.8\num/ps. The associated transient electrical field evolves at intervals ranging\nfrom picoseconds to nanoseconds. These results provide a dynamic perspective on\nthe photoemission properties of semiconductor photocathodes."
    },
    {
        "anchor": "Electron-phonon coupling in single-layer MoS2: The electron-phonon coupling strength in the spin-split valence band maximum\nof single-layer MoS$_2$ is studied using angle-resolved photoemission\nspectroscopy and density functional theory-based calculations. Values of the\nelectron-phonon coupling parameter $\\lambda$ are obtained by measuring the\nlinewidth of the spin-split bands as a function of temperature and fitting the\ndata points using a Debye model. The experimental values of $\\lambda$ for the\nupper and lower spin-split bands at K are found to be 0.05 and 0.32,\nrespectively, in excellent agreement with the calculated values for a\nfree-standing single-layer MoS$_2$. The results are discussed in the context of\nspin and phase-space restricted scattering channels, as reported earlier for\nsingle-layer WS$_2$ on Au(111). The fact that the absolute valence band maximum\nin single-layer MoS$_2$ at K is almost degenerate with the local valence band\nmaximum at $\\Gamma$ can potentially be used to tune the strength of the\nelectron-phonon interaction in this material.",
        "positive": "Glasslike phonon excitation caused by ferroelectric structural\n  instability: Quest for new states of matter near an ordered phase is a promising route for\nmaking modern physics forward. By probing thermal properties of a ferroelectric\n(FE) crystal Ba1-xSrxAl2O4, we have clarified that low-energy excitation of\nacoustic phonons is remarkably enhanced with critical behavior at the border of\nthe FE phase. The phonon spectrum is significantly damped toward the FE phase\nboundary and transforms into glasslike phonon excitation which is reminiscent\nof a boson peak. This system thus links long-standing issues of amorphous\nsolids and structural instability in crystals to pave the way to controlling\nlattice fluctuation as a new tuning parameter."
    },
    {
        "anchor": "Cross-Sectional Scanning Tunneling Microscopy and Spectroscopy of\n  Semimetallic ErAs Nanostructures Embedded in GaAs: The growth and atomic/electronic structure of molecular beam epitaxy\n(MBE)-grown ErAs nanoparticles and nanorods embedded within a GaAs matrix are\nexamined for the first time via cross-sectional scanning tunneling microscopy\n(XSTM) and spectroscopy (XSTS). Cross sections enable the interrogation of the\ninternal structure and are well suited for studying embedded nanostructures.\nThe early stages of embedded ErAs nanostructure growth are examined via these\ntechniques and compared with previous cross sectional TEM work. Tunneling\nspectroscopy I(V) for both ErAs nanoparticles and nanorods was also performed,\ndemonstrating that both nanostructures are semimetallic.",
        "positive": "Nanoscale ferroelectricity in pseudo-cubic sol-gel derived barium\n  titanate -- bismuth ferrite (BaTiO$_3$-BiFeO$_3$) solid solutions: Single phase barium titanate-bismuth ferrite ((1-x)BaTi$_3$-(x)BiFe$_3$,\nBTO-BFO) solid solutions were prepared using citric acid and ethylene glycol\nassisted sol-gel synthesis method. Depending on the dopant content the samples\nare characterized by tetragonal, tetragonal-pseudocubic, pseudocubic and\nrhombohedral structure as confirmed by Raman spectroscopy and XRD measurements.\nAn increase of the BFO content leads to a reduction in the cell parameters\naccompanied by a decrease in polar distortion of the unit cell wherein an\naverage particle size increases from 60 up to 350 nm. Non zero piezoresponse\nwas observed in the compounds with pseudocubic structure while no polar\ndistortion was detected in their crystal structure using X-ray diffraction\nmethod. The origin of the observed non-negligible piezoresponse was discussed\nassuming a coexistence of nanoscale polar and non-polar phases attributed to\nthe solid solutions with high BFO content. A coexistence of the nanoscale\nregions having polar and non-polar character is considered as a key factor to\nincrease macroscopic piezoresponse in the related compounds due to increased\nmobility of the domain walls and phase boundaries."
    },
    {
        "anchor": "Impact of 3D curvature on the polarization orientation in non-Ising\n  domain walls: Ferroelectric domain boundaries are quasi-two-dimensional functional\ninterfaces with high prospects for nanoelectronic applications. Despite their\nreduced dimensionality, they can exhibit complex non-Ising polarization\nconfigurations and unexpected physical properties. Here, the impact of the\nthree-dimensional (3D) curvature on the polarization profile of nominally\nuncharged 180{\\deg} domain walls in LiNbO3 is studied using second-harmonic\ngeneration microscopy and 3D polarimetry analysis. Correlations between the\ndomain wall curvature and the variation of its internal polarization unfold in\nthe form of modulations of the N\\'eel-like character, which we attribute to the\nflexoelectric effect. While the N\\'eel-like character originates mainly from\nthe tilting of the domain wall, the internal polarization adjusts its\norientation due to the synergetic upshot of dipolar and monopolar bound charges\nand their variation with the 3D curvature. Our results show that curved\ninterfaces in solid crystals may offer a rich playground for tailoring\nnanoscale polar states.",
        "positive": "SOS: Symmetry Operational Similarity: Symmetry often governs condensed matter physics. The act of breaking symmetry\nspontaneously leads to phase transitions, and various observables or observable\nphysical phenomena can be directly associated with broken symmetries. Examples\ninclude ferroelectric polarization, ferromagnetic magnetization, optical\nactivities (including Faraday and magneto-optic Kerr rotations), second\nharmonic generation, photogalvanic effects, nonreciprocity, various\nHall-effect-type transport properties, and multiferroicity. Herein, we propose\nthat observable physical phenomena can occur when specimen constituents (i.e.,\nlattice distortions or spin arrangements, in external fields or other\nenvironments, etc.) and measuring probes/quantities (i.e., propagating light,\nelectrons or other particles in various polarization states, including vortex\nbeams of light and electrons, bulk polarization or magnetization, etc.) share\nsymmetry operational similarity (SOS) in relation to broken symmetries. In\naddition, quasi-equilibrium electronic transport processes such as diode-type\ntransport effects, linear or circular photogalvanic effects, Hall-effect-type\ntransport properties ((planar) Hall, Ettingshausen, Nernst, thermal Hall, spin\nHall, and spin Nernst effects) can be understood in terms of symmetry\noperational systematics. The power of the SOS approach lies in providing simple\nand physically transparent views of otherwise unintuitive phenomena in complex\nmaterials. In turn, this approach can be leveraged to identify new materials\nthat exhibit potentially desired properties as well as new phenomena in known\nmaterials."
    },
    {
        "anchor": "The Structural Complexity of (Bi0.5Na0.5)TiO3-BaTiO3 as Revealed by\n  Raman Spectroscopy: The structural phase diagram of the Pb-free ferroelectric\n(Na1/2Bi1/2)1-xBaxTiO3 (NBT-BT), x<0.1, has been explored by Raman spectroscopy\nat temperatures from 10 to 470 K. The data provide clear evidence for a\nproposed temperature-independent morphotropic phase boundary at x \\approx\n0.055. However, there is no evidence for a structural phase transition across T\n\\approx 370 K for x > 0.055, where bulk-property anomalies appear to signal a\ntransition to a nonpolar or antiferroelectric phase. The results identify that\nthe phase above 370 K shows short-range ionic displacements that are identical\nto those in the long-range-ordered phase below 370 K. These conclusions provide\na natural interpretation of the weak piezoelectric response in this system and\nhave important implications for the search for Pb-free piezoelectrics.",
        "positive": "Beyond the Maxwell Limit: Thermal Conduction in Nanofluids with\n  Percolating Fluid Structures: In a well-dispersed nanofluid with strong cluster-fluid attraction, thermal\nconduction paths can arise through percolating amorphous-like interfacial\nstructures. This results in a thermal conductivity enhancement beyond the\nMaxwell limit of 3*phi, with phi being the nanoparticle volume fraction. Our\nfindings from non-equilibrium molecular dynamics simulations, which are\namenable to experimental verification, can provide a theoretical basis for the\ndevelopment of future nanofluids."
    },
    {
        "anchor": "Optimum heat treatment to enhance the weak-linkresponse of Y123\n  nanowires prepared by SolutionBlow Spinning: Although the production of YBa$_{2}$Cu$_{3}$O$_{7-\\delta}$ (Y123) has been\nextensively reported, there is still a lack of information on the ideal heat\ntreatment to produce this material in the form of one dimension nanostructures.\nThus, by means of the Solution Blow Spinning technique, metals embedded in\npolymer fibers were prepared. These polymer composite fibers were fired and\nthen investigated by thermogravimetric analysis. The maximum sintering\ntemperatures of heat treatment were chosen in the interval\n\\SI{850}{\\celsius}-\\SI{925}{\\celsius} for one hour under oxygen flux. SEM\nimages allowed us to determine the wire diameter as approximately 350~nm for\nall samples, as well as to map the evolution of the entangled wire morphology\nwith the sintering temperature. XRD analysis indicated the presence of Y123 and\nsecondary phases in all samples. Ac magnetic susceptibility and dc\nmagnetization measurements demonstrated that the sample sintered at\n\\SI{925}{\\celsius}/1h is the one with the highest weak-link critical\ntemperature and the largest diamagnetic response.",
        "positive": "Spin-pumping-induced spin transport in p-type Si at room temperature: A spin battery concept is applied for the dynamical generation of pure spin\ncurrent and spin transport in p-type silicon (p-Si). Ferromagnetic resonance\nand effective s-d coupling in Ni80Fe20 results in spin accumulation at the\nNi80Fe20/p-Si interface, inducing spin injection and the generation of spin\ncurrent in the p-Si. The pure spin current is converted to a charge current by\nthe inverse spin Hall effect of Pd evaporated onto the p-Si. This approach\ndemonstrates the generation and transport of pure spin current in p-Si at room\ntemperature."
    },
    {
        "anchor": "Coherent control of magnetization precession by double-pulse activation\n  of effective fields from magnetoacoustics and demagnetization: We demonstrate the coherent optical control of magnetization precession in a\nthin Ni film by a second excitation pulse which amplifies or attenuates the\nprecession induced by a first pulse depending on the fluences of the\npump-pulses and the pump-pump delay. This control goes beyond the conventional\nstrategy, where the same mechanism drives the precession in or out-of phase. We\nbalance the magneto-acoustic mechanism driven by quasi-static strain and the\nshape-anisotropy change triggered by laser-induced demagnetization. These\nmechanisms tilt the transient effective magnetic field in opposite directions\nin case of negative magneto-elastic coupling ($b_1<0$). While the strain\nresponse is linear in the fluence, demagnetization is nonlinear near the Curie\ntemperature, enabling fluence-based control scenarios.",
        "positive": "First Principle Study of Electron Transport in Single-Walled Carbon\n  Nanotubes of 2 to 22 nm in Length: An elongation method based on ab initio quantum chemistry approaches is\npresented. It allows to study electronic structures and coherent electron\ntransportation properties of single-walled carbon nanotubes (SWCNTs) up to 22nm\nin length using the hybrid density functional theory. The 22nm long SWCNT,\nconsisting of more than ten thousands electrons, is the largest carbon nanotube\nthat has ever been studied at such a sophisticated all-electron level.\nInteresting oscillating behaviour of the energy gap with respect to the length\nof the nanotube is revealed. The calculated current-voltage characteristics of\nSWCNTs are in excellent agreement with recent experimental results. It confirms\nthe experimental observation that a 15nm long SWCNT is still largely a\nballistic transport device. The proposed elongation method opens up a new door\nfor the first principle study of nano- and bio-electronics."
    },
    {
        "anchor": "A Study of Electronic and Magnetic Properties of Transition Metal\n  Trihalides: We present the electronic and magnetic structure calculations of VCl3, VBr3,\nCrCl3 and CrBr3. The results are obtained by density functional theory with\nplane wave basis sets. The trihalides generally optimize either in trigonal or\nmonoclinic structures. We have focused on the effect of symmetry on the\nelectronic and magnetic properties of the systems. We have found that magnetic\nmoments change considerably depending on the symmetry. Both CrX3 have shown a\nbandgap around 2eV while the V-based systems have shown half-metallic\nproperties.",
        "positive": "Electron Localization at Metal Surfaces: We investigate some surfaces of a paradigmatic sp bonded metal--namely,\nAl(110), Al(100), and Al(111)--by means of the \"electron localization function\"\n(ELF), implemented in a first-principle pseudopotential framework. ELF is a\nground-state property which discriminates in a very sharp, quantitative, way\nbetween different kinds of bonding. ELF shows that in the bulk of Al the\nelectron distribution is essentially jelliumlike, while what happens at the\nsurface strongly depends on packing. At the least packed surface, Al(110), ELF\nindicates a free-atom nature of the electron distribution in the outer region.\nThe most packed surface, Al(111), is instead at the opposite end, and can be\nregarded as a jellium surface weakly perturbed by the presence of the ionic\ncores."
    },
    {
        "anchor": "Correlation-driven topological and valley states in monolayer\n  VSi$_{2}$P$_{4}$: Electronic correlations could have significant impact on the material\nproperties. They are typically pronounced for localized orbitals and enhanced\nin low-dimensional systems, so two-dimensional (2D) transition metal compounds\ncould be a good platform to study their effects. Recently, a new class of 2D\ntransition metal compounds, the MoSi$_2$N$_4$-family materials, have been\ndiscovered, and some of them exhibit intrinsic magnetism. Here, taking\nmonolayer VSi$_{2}$P$_{4}$ as an example from the family, we investigate the\nimpact of correlation effects on its physical properties, based on the\nfirst-principles calculations. We find that different correlation strength can\ndrive the system into a variety of interesting ground states, with rich\nmagnetic, topological and valley features. With increasing correlation\nstrength, while the system favors a ferromagnetic semiconductor state for most\ncases, the magnetic anisotropy and the band gap type undergo multiple\ntransitions, and in the process, the band edges can form single, two or three\nvalleys for electrons or holes. Remarkably, there is a quantum anomalous Hall\n(QAH) insulator phase, which has a unit Chern number. The boundary of the QAH\nphase correspond to the half-valley semimetal state with fully valley polarized\nbulk carriers. We further show that for phases with the out-of-plane magnetic\nanisotropy, the interplay between spin-orbit coupling and orbital character of\nvalleys enable an intrinsic valley polarization for electrons but not for\nholes. This electron valley polarization can be switched by reversing the\nmagnetization direction, providing a new route of magnetic control of\nvalleytronics. Our result sheds light on the possible role of correlation\neffects in the 2D transition metal compounds, and it will open new perspectives\nfor spintronic, valleytronic and topological nanoelectronic applications based\non these materials.",
        "positive": "Study of In-plane and Interlayer Interactions During Aluminum Fluoride\n  Intercalation in Graphite: Implications for the Development of Rechargeable\n  Batteries: The electrolyte intercalation mechanism facilitates the insertion/extraction\nof charge into the electrode material in rechargeable batteries. Aluminum\nfluoride (AlF$_{3}$) has been used as an electrolyte in rechargeable aluminum\nbatteries with graphite electrodes, demonstrating improved reversibility of\nbattery charging and discharging processes; however, the intercalation\nmechanism of this neutral molecule in graphite is so far unknown. In this work,\nwe combine scanning tunneling microscopy (STM) in ultra-high vacuum conditions,\ncalculations based on density functional theory, and large-scale molecular\ndynamics simulations to reveal the mechanism of AlF$_{3}$ intercalation in\nhighly oriented pyrolytic graphite (HOPG). We report the formation of AlF$_{3}$\nmolecules clusters between graphite layers, their self-assembly by graphene\nbuckling-mediated interactions, and explain the origin and distribution of\nsuperficial {\\it blisters} in the material. Our findings have implications for\nunderstanding the relationship between the mobility and clustering of molecules\nand the expansion of the anode material. This, in turn, paves the way for\nfuture enhancements in the performance of energy storage systems."
    },
    {
        "anchor": "Langevin spin dynamics based on ab initio calculations: numerical\n  schemes and applications: A method is proposed to study the finite-temperature behaviour of small\nmagnetic clusters based on solving the stochastic Landau-Lifshitz-Gilbert\nequations, where the effective magnetic field is calculated directly during the\nsolution of the dynamical equations from first principles instead of relying on\nan effective spin Hamiltonian. Different numerical solvers are discussed in the\ncase of a one-dimensional Heisenberg chain with nearest-neighbour interactions.\nWe performed detailed investigations for a monatomic chain of ten Co atoms on\ntop of Au(001) surface. We found a spiral-like ground state of the spins due to\nDzyaloshinsky-Moriya interactions, while the finite-temperature magnetic\nbehaviour of the system was well described by a nearest-neighbour Heisenberg\nmodel including easy-axis anisotropy.",
        "positive": "Tunable Localization and Oscillation of Coupled Plasmon Waves in Graded\n  Plasmonic Chains: The localization (confinement) of coupled plasmon modes, named as gradons,\nhas been studied in metal nanoparticle chains immersed in a graded dielectric\nhost. We exploited the time evolution of various initial wavepackets formed by\nthe linear combination of the coupled modes. We found an important interplay\nbetween the localization of plasmonic gradons and the oscillation in such\ngraded plasmonic chains. Unlike in optical superlattices, gradient cannot\nalways lead to Bloch oscillations, which can only occur for wavepackets\nconsisting of particular types of gradons. Moreover, the wavepackets will\nundergo different forms of oscillations. The correspondence can be applied to\ndesign a variety of optical devices by steering among various oscillations."
    },
    {
        "anchor": "Electronic structure and physical properties of 13C carbon composite: This review is devoted to the application of graphite and graphite composites\nin science and technology. Structure and electrical properties, as so\ntechnological aspects of producing of high-strength artificial graphite and\ndynamics of its destruction are considered. These type of graphite are\ntraditionally used in the nuclear industry. Author was focused on the\nproperties of graphite composites based on carbon isotope 13C. Generally, the\nreview relies on the original results and concentrates on actual problems of\napplication and testing of graphite materials in modern nuclear physics and\nscience and its technology applications. Translated by author from chapters 5\nof the Russian monograph by Zhmurikov E.I., Bubnenkov I.A., Pokrovsky A.S. et\nal. Graphite in Science and Nuclear Technique eprint arXiv:1307.1869, 07/2013\n(BC 2013arXiv1307.1869Z",
        "positive": "Switching intrinsic magnetic skyrmions with controllable magnetic\n  anisotropy in van der Waals multiferroic heterostructures: Magnetic skyrmions, topologically nontrivial whirling spin textures at\nnanometer scales, have emerged as potential information carriers for spintronic\ndevices. The ability to efficiently create and erase magnetic skyrmions is\nvital yet challenging for such applications. Based on first-principles studies,\nwe find that switching between intrinsic magnetic skyrmion and high-temperature\nferromagnetic states can be achieved in two-dimensional van der Waals (vdW)\nmultiferroic heterostructure CrSeI/In2Te3 by reversing the ferroelectric\npolarization of In2Te3. The core mechanism of this switching is traced to the\ncontrollable magnetic anisotropy of CrSeI influenced by the ferroelectric\npolarization of In2Te3. We propose a useful descriptor linking the presence of\nmagnetic skyrmions to magnetic parameters, and validate this connection through\nstudies of a variety of similar vdW multiferroic heterostructures. Our work\ndemonstrates that manipulating magnetic skyrmions via tunable magnetic\nanisotropies in vdW multiferroic heterostructures represents a highly promising\nand energy-efficient strategy for future development of spintronics."
    },
    {
        "anchor": "On Curie temperature of B20-MnSi films: B20-type MnSi is the prototype magnetic skyrmion material. Thin films of MnSi\nshow a higher Curie temperature than their bulk counterpart. However, it is not\nyet clear what mechanism leads to the increase of the Curie temperature. In\nthis work, we grow MnSi films on Si(100) and Si(111) substrates with a broad\nvariation in their structures. By controlling the Mn thickness and annealing\nparameters, the pure MnSi phase of polycrystalline and textured nature as well\nas the mixed phase of MnSi and MnSi1.7 are obtained. Surprisingly, all these\nMnSi films show an increased Curie temperature of up to around 43 K. The Curie\ntemperature is likely independent of the structural parameters within our\naccessibility including the film thickness above a threshold, strain, cell\nvolume and the mixture with MnSi1.7. However, a pronounced phonon softening is\nobserved for all samples, which can tentatively be attributed to slight Mn\nexcess from stoichiometry, leading to the increased Curie temperature.",
        "positive": "Energy Dependent Contrast in Atomic-Scale Spin-Polarized Scanning\n  Tunneling Microscopy ofMn3N2(010): Experiment and First-Principles Theory: The technique of spin-polarized scanning tunneling microscopy is investigated\nfor its use in determining fine details of surface magnetic structure down to\nthe atomic scale. As a model sample, the row-wise anti-ferromagnetic Mn3N2(010)\nsurface is studied. It is shown that the magnetic contrast in atomic-scale\nimages is a strong function of the bias voltage around the Fermi level.\nInversion of the magnetic contrast is also demonstrated. The experimental\nSP-STM images and height profiles are compared with simulated SP-STM images and\nheight profiles based on spin-polarized density functional theory. The success\nof different tip models in reproducing the non-magnetic and magnetic STM data\nis explored."
    },
    {
        "anchor": "Tunable magnon-photon coupling in a compensating ferrimagnet - from weak\n  to strong coupling: We experimentally study the magnon-photon coupling in a system consitsing of\nthe compensating ferrimagnet gadolinium iron garnet (GdIG) and a\nthree-dimensional microwave cavity. The temperature is varied in order to tune\nthe GdIG magnetization and to observe the transition from the weak coupling\nregime to the strong coupling regime. By measuring and modelling the complex\nreflection parameter of the system the effective coupling rate g eff and the\nmagnetization M eff of the sample are extracted. Comparing g eff with the\nmagnon and the cavity decay rate we conclude that the strong coupling regime is\neasily accessible using GdIG. We show that the effective coupling strength\nfollows the predicted square root dependence on the magnetization.",
        "positive": "Efficient Interlayer Relaxation and Transition of Excitons in Epitaxial\n  and Non-epitaxial MoS2/WS2 Heterostructures: Semiconductor heterostructures provide a powerful platform for the\nengineering of excitons. Here we report the excitonic properties of\ntwo-dimensional (2D) heterostructures that consist of monolayer MoS2 and WS2\nstacked epitaxially or non-epitaxially in the vertical direction. We find\nsimilarly efficient interlayer relaxation and transition of excitons in both\nthe epitaxial and nonepitaxial heterostructures. This is manifested by a two\norders of magnitude decrease in the photoluminescence and the appearance of an\nextra absorption peak at low energy region. The MoS2/WS2 heterostructures show\nweak interlayer coupling and can essentially act as atomicscale heterojunctions\nwith the intrinsic bandstructures of the two monolayers largely preserved. They\nare particularly promising for the applications that request efficient\ndissociation of excitons and strong light absorption, including photovoltaics,\nsolar fuels, photodetectors, and optical modulators. Our results also indicate\nthat 2D heterostructures promise unprecedented capabilities to engineer\nexcitons from the atomic level without concerns of interfacial imperfection."
    },
    {
        "anchor": "Tetragonal and trigonal deformations in zinc-blende semiconductors : a\n  tight-binding point of view: The deformation potentials of cubic semiconductors are re-examined from the\npoint of view of the extended-basis $sp^3d^5s^*$ tight-binding model. Previous\nparametrizations had failed to account properly for trigonal deformations, even\nleading to incorrect sign of the acoustic component of the shear deformation\npotential {\\it d}. The strain-induced shifts and splittings of the on-site\nenergies of the p- and d-orbitals are shown to play a prominent role in\nobtaining satisfactory values of deformation potentials both at the zone center\nand zone extrema. The present approach results in excellent agreement with\navailable experimental data and ab-initio calculations.",
        "positive": "First principles evaluation of fcc ruthenium for use in advanced\n  interconnects: As the semiconductor industry turns to alternate conductors to replace Cu for\nfuture interconnect nodes, much attention as been focused on evaluating the\nelectrical performance of Ru. The typical hexagonal close-packed (hcp) phase\nhas been extensively studied, but relatively little attention has been paid to\nthe face-centered cubic (fcc) phase, which has been shown to nucleate in\nconfined structures and may be present in tight-pitch interconnects. Using\n\\emph{ab initio} techniques, we benchmark the performance of fcc Ru. We find\nthat the phonon-limited bulk resistivity of the fcc Ru is less than half of\nthat of hcp Ru, a feature we trace back to the stronger electron-phonon\ncoupling elements that are geometrically inherited from the modified Fermi\nsurface shape of the fcc crystal. Despite this benefit of the fcc phase, high\ngrain boundary scattering results in increased resistivity compared to Cu-based\ninterconnects with similar average grain size. We find, however, that the line\nresistance of fcc Ru is lower than that of Cu below 21 nm line width due to the\nconductor volume lost to adhesion and wetting liners. In addition to studying\nbulk transport properties, we evaluate the performance of adhesion liners for\nfcc Ru. We find that it is energetically more favorable for fcc Ru to bind\ndirectly to silicon dioxide than through conventional adhesion liners such as\nTaN and TiN. In the case that a thin liner is necessary for the Ru deposition\ntechnique, we find that the vertical resistance penalty of a liner for fcc Ru\ncan be up to eight times lower than that calculated for conventional liners\nused for Cu interconnects. Our calculations, therefore, suggest that the\nformation of the fcc phase of Ru may be a beneficial for advanced,\nlow-resistance interconnects."
    },
    {
        "anchor": "Cu-based metalorganic systems: an ab initio study of the electronic\n  structure: Within a first principles framework, we study the electronic structure of the\nrecently synthesized polymeric coordination compound\nCu(II)-2,5-bis(pyrazol-1-yl)-1,4-dihydroxybenzene (CuCCP), which has been\nsuggested to be a good realization of a Heisenberg spin-1/2 chain with\nantiferromagnetic coupling. By using a combination of classical with ab initio\nquantum mechanical methods, we design on the computer reliable modified\nstructures of CuCCP aimed at studying effects of Cu-Cu coupling strength\nvariations on this spin-1/2 system. For this purpose, we performed two types of\nmodifications on CuCCP. In one case, we replaced H in the linker by i) an\nelectron donating group (NH2) and ii) an electron withdrawing group (CN), while\nthe other modification consisted in adding H2O and NH3 molecules in the\nstructure which change the local coordination of the Cu(II) ions. With the\nNMTO-downfolding method we provide a quantitative analysis of the modified\nelectronic structure and the nature of the Cu-Cu interaction paths in these new\nstructures and discuss its implications for the underlying microscopic model.",
        "positive": "Ferromagnetic Enhancement in LaMnO3 Films with Release and Flexure: A variety of novel phenomena and functionalities emerge from lowering the\ndimensionality of materials and enriching the degrees of freedom in modulation.\nIn this work, it is found that the saturation magnetization of LaMnO3 (LMO)\nfilms is largely enhanced by 56% after releasing from a brand-new phase of\ntetragonal strontium aluminate buffer layer, and is significantly increased by\n92% with bending films to a curvature of 1 mm-1 using a water-assisted\ndirect-transferring method. Meanwhile, the Curie temperature of LMO films has\nbeen improved by 13 K. High-resolution spherical aberration-corrected scanning\ntransmission electron microscopy and first-principles calculations\nunambiguously demonstrate that the enhanced ferromagnetism is attributed to the\nstrengthened Mn-O-Mn super-exchange interactions from the augmented\ncharacteristics of the unconventional P21/n structure caused by the\nout-of-plane lattice shrinking after strain releasing and increased flexure\ndegree of freestanding LMO films. This work paves a way to achieve large-scale\nand crack-and-wrinkle-free freestanding films of oxides with largely improved\nfunctionalities."
    },
    {
        "anchor": "Anisotropic exchange Hamiltonian, magnetic phase diagram and domain\n  inversion of Nd$_2$Zr$_2$O$_7$: We present thermodynamic and neutron scattering measurements on the quantum\nspin ice candidate Nd$_2$Zr$_2$O$_7$. The parameterization of the anisotropic\nexchange Hamiltonian is refined based on high-energy-resolution inelastic\nneutron scattering data together with thermodynamic data using linear spin wave\ntheory and numerical linked cluster expansion. Magnetic phase diagrams are\ncalculated using classical Monte Carlo simulations with fields along\n\\mbox{[100]}, \\mbox{[110]} and \\mbox{[111]} crystallographic directions which\nagree qualitatively with the experiment. Large hysteresis and irreversibility\nfor \\mbox{[111]} is reproduced and the microscopic mechanism is revealed by\nmean field calculations to be the existence of metastable states and domain\ninversion. Our results shed light on the explanations of the recently observed\ndynamical kagome ice in Nd$_2$Zr$_2$O$_7$ in \\mbox{[111]} fields.",
        "positive": "Nonlinear Anisotropic Viscoelasticity: In this paper we revisit the mathematical foundations of nonlinear\nviscoelasticity. We study the underlying geometry of viscoelastic deformations,\nand in particular, the intermediate configuration. Starting from the\nmultiplicative decomposition of deformation gradient into elastic and viscous\nparts $\\mathbf{F}=\\Fe\\Fv\\,$, we point out that $\\Fv$ can be either a material\ntensor ($\\Fe$ is a two-point tensor) or a two-point tensor ($\\Fe$ is a spatial\ntensor). We show that based on physical grounds the second choice is\nunacceptable. It is assumed that the free energy density is the sum of an\nequilibrium and a non-equilibrium part. The symmetry transformations and their\naction on the total, elastic, and viscous deformation gradients are carefully\ndiscussed. Following a two-potential approach the governing equations of\nnonlinear viscoelasticity are derived using the Lagrange-d'Alembert principle.\nWe discuss the constitutive and kinetic equations for compressible and\nincompressible isotropic, transversely isotropic, orthotropic, and monoclinic\nviscoelastic solids. We finally semi-analytically study creep and relaxation in\nthree examples of universal deformations."
    },
    {
        "anchor": "Reversal modes in magnetic nanotubes: The magnetic switching of ferromagnetic nanotubes is investigated as a\nfunction of their geometry. Two independent methods are used: Numerical\nsimulations and analytical calculations. It is found that for long tubes the\nreversal of magnetization is achieved by two mechanism: The propagation of a\ntransverse or a vortex domain wall depending on the internal and external radii\nof the tube.",
        "positive": "Temperature-dependent optical properties of gold thin films: Understanding the temperature dependence of the optical properties of thin\nmetal films is critical for designing practical devices for high temperature\napplications in a variety of research areas, including plasmonics and\nnear-field radiative heat transfer. Even though the optical properties of bulk\nmetals at elevated temperatures have been studied, the temperature-dependent\ndata for thin metal films, with thicknesses ranging from few tens to few\nhundreds of nanometers, is largely missing. In this work we report on the\noptical constants of single- and polycrystalline gold thin films at elevated\ntemperatures in the wavelength range from 370 to 2000 nm. Our results show that\nwhile the real part of the dielectric function changes marginally with\nincreasing temperature, the imaginary part changes drastically. For\n200-nm-thick single- and polycrystalline gold films the imaginary part of the\ndielectric function at 500 0C becomes nearly twice larger than that at room\ntemperature. In contrast, in thinner films (50-nm and 30-nm) the imaginary part\ncan show either increasing or decreasing behavior within the same temperature\nrange and eventually at 500 0C it becomes nearly 3-4 times larger than that at\nroom temperature. The increase in the imaginary part at elevated temperatures\nsignificantly reduces the surface plasmon polariton propagation length and the\nquality factor of the localized surface plasmon resonance for a spherical\nparticle. We provide experiment-fitted models to describe the\ntemperature-dependent gold dielectric function as a sum of one Drude and two\nCritical Point oscillators. These causal analytical models could enable\naccurate multiphysics modelling of gold-based nanophotonic and plasmonic\nelements in both frequency and time domains."
    },
    {
        "anchor": "Pump-induced terahertz conductivity response and peculiar bound state in\n  Mn3Si2Te6: We report the significant enhancement on ultrafast terahertz optical\nconductivity and the unexpected formation of a polaronic-like state in\nsemiconductor Mn3Si2Te6 at room temperature. With the absorption of pump\nphotons, the low-frequency terahertz photoconductivity spectrum exhibits a\nsignificant rise, quickly forming a broad peak and subsequently shifting to\nhigher energy. The short-lived nature of the broad peak, as well as the\ndistribution of optical constants, strongly points towards a transient polaron\nmechanism. Our study not only provides profound insights into the remarkable\nphotoelectric response of Mn3Si2Te6 but also highlights its significant\npotential for future photoelectric applications.",
        "positive": "Temperature-dependent optical spectra of single-crystal\n  (CH$_3$NH$_3$)PbBr$_3$ cleaved in ultrahigh vacuum: We measure temperature-dependent one-photon and two-photon induced\nphotoluminescence from (CH3NH3)PbBr3 single crystals cleaved in ultrahigh\nvacuum. An approach is presented to extract absorption spectra from a\ncomparison of both measurements. Cleaved crystals exhibit broad\nphotoluminescence spectra. We identify the direct optical band gap of 2.31 eV.\nBelow 200 K the band gap increases with temperature, and it decreases at\nelevated temperature, as described by the Bose-Einstein model. An excitonic\ntransition is found 22 meV below the band gap at temperatures <200 K. Defect\nemission occurs at photon energies <2.16 eV. In addition, we observe a\ntransition at 2.25 eV (2.22 eV) in the orthorhombic (tetragonal and cubic)\nphase. Below 200 K, the associated exciton binding energy is also 22 meV, and\nthe transition redshifts at higher temperature. The binding energy of the\nexciton related to the direct band gap, in contrast, decreases in the cubic\nphase. High-energy emission from free carriers is observed with higher\nintensity than reported in earlier studies. It disappears after exposing the\ncrystals to air."
    },
    {
        "anchor": "Two dimensional electron gas in the $\u03b4$-doped iridates with strong\n  spin-orbit coupling: La$_\u03b4$Sr$_2$IrO$_4$: Iridates are of considerable current interest because of the strong\nspin-orbit coupling that leads to a variety of new phenomena. Using\ndensity-functional studies, we predict the formation of a spin-orbital\nentangled two-dimensional electron gas (2DEG) in the $\\delta$-doped iridate\nLa$_\\delta$Sr$_2$IrO$_4$, where a single SrO layer is replaced by a LaO layer.\nThe extra La electron resides close to the $\\delta$-doped layer, partially\noccupying the $J_{\\rm eff}= 1/2 $ upper Hubbard band and thereby making the\ninterface metallic. The magnetic structure of the bulk is destroyed near the\ninterface, with the Ir$_0$ layer closest to the interface becoming\nnon-magnetic, while the next layer (Ir$_1$) continues to maintain the AFM\nstructure of the bulk, but with a reduced magnetic moment. The Fermi surface\nconsists of a hole pocket and an electron pocket, located in two different Ir\nlayers (Ir$_0$ and Ir$_1$), with both carriers derived from the $J_{\\rm eff}=\n1/2 $ upper Hubbard band. The presence of both electrons and holes at the\n$\\delta$-doped interface suggests unusual transport properties, leading to\npossible device applications.",
        "positive": "Spin conductance of YIG thin films driven from thermal to subthermal\n  magnons regime by large spin-orbit torque: We report a study on spin conductance in ultra-thin films of Yttrium Iron\nGarnet (YIG), where spin transport is provided by propagating spin waves, that\nare generated and detected by direct and inverse spin Hall effects in two Pt\nwires deposited on top. While at low current the spin conductance is dominated\nby transport of thermal magnons, at high current, the spin conductance is\ndominated by low-damping non-equilibrium magnons thermalized near the spectral\nbottom by magnon-magnon interaction, with consequent a sensitivity to the\napplied magnetic field and a longer decay length. This picture is supported by\nmicrofocus Brillouin Light Scattering spectroscopy."
    },
    {
        "anchor": "Lattice dynamics in mono- and few-layer sheets of WS2 and WSe2: Thickness is one of the fundamental parameters that define the electronic,\noptical, and thermal properties of two-dimensional (2D) crystals. Phonons in\nmolybdenum disulfide (MoS2) were recently found to exhibit unique thickness\ndependence due to interplay between short and long range interactions. Here we\nreport Raman spectra of atomically thin sheets of WS2 and WSe2 in the mono- to\nfew-layer thickness regime. We show that, similar to the case of MoS2, the\ncharacteristic and modes exhibit stiffening and softening with increasing\nnumber of layers, respectively, with a small shift of less than 3 cm-1 due to\nlarge mass of the atoms. Thickness dependence is also observed in a series of\nmultiphonon bands arising from overtone, combination, and zone edge phonons,\nwhose intensity exhibit significant enhancement in excitonic resonance\nconditions. Some of these multiphonon peaks are found to be absent only in\nmonolayers. These features provide a unique fingerprint and rapid\nidentification for monolayer flakes.",
        "positive": "Friction in nanoelectromechanical systems: Clamping loss in the GHz\n  regime: The performance of a wide variety of ultra-sensitive devices employing\nnanoelectromechanical resonators is determined by their mechanical quality\nfactor, yet energy dissipation in these systems remains poorly understood. Here\nwe develop a comprehensive theory of friction in high frequency resonators\ncaused by the radiation of elastic energy into the support substrate, referred\nto as clamping loss. The elastic radiation rate is found to be a strong\nincreasing function of resonator frequency, and we argue that this mechanism\nwill play an important role in future microwave-frequency devices."
    },
    {
        "anchor": "Theoretical investigation on the ferromagnetic two-dimensional scandium\n  monochloride sheet that has a high Curie temperature and could be exfoliated\n  from a known material: A two-dimensional scandium monochloride sheet was investigated by using\ndensity functional theory. It could be exfoliated from a known bulk material\nwith a cleavage energy slightly lower than that of graphene. The sheet has a\nferromagnetic ground state with a Curie temperature of 100 K. Moreover, the\nsheet becomes a half-metal under hole doping. The Curie temperature increases\nto 250 K with the doping amount of 0.4 per primitive cell, which is close to\nthe ice point. The two-dimensional scandium monochloride sheet should be a good\ncandidate for two-dimensional spintronics.",
        "positive": "A Universal Description of Workfunction: At the surfaces of materials, the bulk symmetry of the charge density is\nbroken and electron spill-out into the vacuum region creates a surface dipole.\nSuch spill-out has been historically calculated by Lang and Kohn [Phys. Rev. B\n\\textbf{3}, 1215 (1971)] using average electron density to sucessfully explain\nthe workfunction in metals. However, despite its initial success, in the fifty\nyears since it has not been extended beyond simple metals. Here we show that\nthe degree of charge spill-out is largely controlled by the innate bulk\nworkfunction $\\phi_I$, which is the Fermi level position of $\\it bulk$ relative\nto the ideal vacuum. By incorporating the contribution of $\\phi_I$ to the\nsurface dipole we show that Lang-Kohn's $\\it jellium$ based approach can be\nbroadly expanded to understand the workfunction over a wide range of metals,\nsemiconductors, and insulators."
    },
    {
        "anchor": "High-frequency magnon excitation due to femtosecond spin-transfer\n  torques: Femtosecond laser pulses can induce ultrafast demagnetization as well as\ngenerate bursts of hot electron spin currents. In trilayer spin valves\nconsisting of two metallic ferromagnetic layers separated by a nonmagnetic one,\nhot electron spin currents excited by an ultrashort laser pulse propagate from\nthe first ferromagnetic layer through the spacer reaching the second magnetic\nlayer. When the magnetizations of the two magnetic layers are noncollinear,\nthis spin current exerts a torque on magnetic moments in the second\nferromagnet. Since this torque is acting only within the sub-ps timescale, it\nexcites coherent high-frequency magnons as recently demonstrated in\nexperiments. Here, we calculate the temporal shape of the hot electron spin\ncurrents using the superdiffusive transport model and simulate the response of\nthe magnetic system to the resulting ultrashort spin-transfer torque pulse by\nmeans of atomistic spin-dynamics simulations. Our results confirm that the\nacting spin-current pulse is short enough to excite magnons with frequencies\nbeyond 1 THz, a frequency range out of reach for current induced spin-transfer\ntorques. We demonstrate the formation of thickness dependent standing spin\nwaves during the first picoseconds after laser excitation. In addition, we vary\nthe penetration depth of the spin-transfer torque to reveal its influence on\nthe excited magnons. Our simulations clearly show a suppression effect of\nmagnons with short wavelengths already for penetration depths in the range of 1\nnm confirming experimental findings reporting penetration depths below $2\\,\n{\\rm nm}$.",
        "positive": "A preliminary study of acoustic propagation in thick foam tissue\n  scaffolds composed of poly(lactic-co-glycolic acid): The exclusive ability of acoustic waves to probe the structural, mechanical\nand fluidic properties of foams may offer novel approaches to characterise the\nporous scaffolds employed in tissue engineering. Motivated by this we conduct a\npreliminary investigation into the acoustic properties of a typical biopolymer\nand the feasibility of acoustic propagation within a foam scaffold thereof.\nFocussing on poly(lactic-co-glycolic acid), we use a pulse-echo method to\ndetermine the longitudinal speed of sound, whose temperature-dependence reveals\nthe glass transition of the polymer. Finally, we demonstrate the first\ntopographic and tomographic acoustic images of polymer foam tissue scaffolds."
    },
    {
        "anchor": "Boron and nitrogen isotope effects on hexagonal boron nitride properties: The unique physical, mechanical, chemical, optical, and electronic properties\nof hexagonal boron nitride (hBN) make it a promising two-dimensional material\nfor electronic, optoelectronic, nanophotonic, and quantum devices. Here we\nreport on the changes in hBN's properties induced by isotopic purification in\nboth boron and nitrogen. Previous studies on isotopically pure hBN have focused\non purifying the boron isotope concentration in hBN from its natural\nconcentration (approximately 20 at$\\%$ $^{10}$B, 80 at$\\%$ $^{11}$B) while\nusing naturally abundant nitrogen (99.6 at$\\%$ $^{14}$N, 0.4 at$\\%$ $^{15}$N),\ni.e. almost pure $^{14}$N. In this study, we extend the class of\nisotopically-purified hBN crystals to $^{15}$N. Crystals in the four\nconfigurations, namely h$^{10}$B$^{14}$N, h$^{11}$B$^{14}$N, h$^{10}$B$^{15}$N,\nand h$^{11}$B$^{15}$N, were grown by the metal flux method using boron and\nnitrogen single isotope ($>99\\%$) enriched sources, with nickel plus chromium\nas the solvent. In-depth Raman and photoluminescence spectroscopies demonstrate\nthe high quality of the monoisotopic hBN crystals with vibrational and optical\nproperties of the $^{15}$N-purified crystals at the state of the art of\ncurrently available $^{14}$N-purified hBN. The growth of high-quality\nh$^{10}$B$^{14}$N, h$^{11}$B$^{14}$N, h$^{10}$B$^{15}$N, and h$^{11}$B$^{15}$N\nopens exciting perspectives for thermal conductivity control in heat\nmanagement, as well as for advanced functionalities in quantum technologies.",
        "positive": "Direct visualization of molecular stacking in quasi-2D hexagonal ice: The structure and properties of water or ice are of great interest to\nresearchers due to their importance in the biological, cryopreservation and\nenvironmental fields. Hexagonal ice (Ih) is a common ice phase in nature and\nhas been extensively studied; however, microstructural investigations at the\natomic or molecular scale are still lacking. In this paper, the fine structure\nof quasi-2-dimensional ice Ih films was directly examined using cryogenic\ntransmission electron microscopy. Two types of thin Ih films were observed:\nperfect single crystals growing along the [0001] direction and crystals with\nstacking faults, including both basal (BSF) and prismatic (PSF) ones, along the\norientation of [11-20]; these results were further confirmed by theoretical\ncalculations. Importantly, for the first time, the stacking faults in ice Ih\nwere directly visualized and resolved. In light of the extension behavior of\nthe chair conformation composed of the water molecules, we elucidated the\nformation mechanism of BSF in Ih, namely, the Ic phase. This study not only\ndetermined the structural characteristics of ice structure at the molecular\nscale but also provided important concepts for researchers to more fully\nunderstand the growth kinetics of ice crystals at the atomic scale."
    },
    {
        "anchor": "Temperature Dependent Empirical Pseudopotential Theory For\n  Self-Assembled Quantum Dots: We develop a temperature dependent empirical pseudopotential theory to study\nthe electronic and optical properties of self-assembled quantum dots (QDs) at\nfinite temperature. The theory takes the effects of both lattice expansion and\nlattice vibration into account. We apply the theory to the InAs/GaAs QDs. For\nthe unstrained InAs/GaAs heterostructure, the conduction band offset increases\nwhereas the valence band offset decreases with increasing of the temperature,\nand there is a type-I to type-II transition at approximately 135 K. Yet, for\nInAs/GaAs QDs, the holes are still localized in the QDs even at room\ntemperature, because the large lattice mismatch between InAs and GaAs greatly\nenhances the valence band offset. The single particle energy levels in the QDs\nshow strong temperature dependence due to the change of confinement potentials.\nBecause of the changes of the band offsets, the electron wave functions\nconfined in QDs increase by about 1 - 5%, whereas the hole wave functions\ndecrease by about 30 - 40% when the temperature increases from 0 to 300 K. The\ncalculated recombination energies of exciton, biexciton and charged excitons\nshow red shifts with increasing of the temperature, which are in excellent\nagreement with available experimental data.",
        "positive": "Gate driven adiabatic quantum pumping in graphene: We propose a new type of quantum pump made out of graphene, adiabatically\ndriven by oscillating voltages applied to two back gates. From a practical\npoint of view, graphene-based quantum pumps present advantages as compared to\nnormal pumps, like enhanced robustness against thermal effects and a wider\nadiabatic range in driving frequency. From a fundamental point of view, apart\nfrom conventional pumping through propagating modes, graphene pumps can tap\ninto evanescent modes, which penetrate deeply into the device as a consequence\nof chirality. At the Dirac point the evanescent modes dominate pumping and give\nrise to a universal response under weak driving for short and wide pumps, even\nthough the charge per unit cycle in not quantized."
    },
    {
        "anchor": "Spin scattering and Hall effects in monolayer Fe3GeTe2: We theoretically show that the carrier transport in monolayer Fe3GeTe2\nexperiences a transition between anomalous Hall effect and spin Hall effect\nwhen the spin polarization of disorders switches between out-of-plane and\nin-plane. These Hall effects are allowed when the magnetization is polarized\nin-plane, breaking the C3 rotation symmetry. The transition originates from the\nselection rule of spin scattering, the strong spin-orbit coupling, and the van\nHove singularities near the Fermi surface. The scattering selection rule\ntolerates the sign change of the disorder spin, which provides a convenient\nmethod to detect the switching of antiferromagnetic insulators regardless of\nthe interfacial roughness in a heterostructure. This provides a convenient\nplatform for the study of 2D spintronics through various van-der-Waals\nheterostructures.",
        "positive": "Atomic correlation energies and the generalized gradient approximation: Careful extrapolation of atomic correlation energies suggests that $E_c$\ntends to $-AZ\\log{Z} + BZ$ as $Z$ tends to infinity, where $Z$ is the atomic\nnumber, $A$ is known, and $B$ is about 38 milliHartrees. The coefficients\nroughly agree with those of the high-density limit of the real-space\nconstruction of the generalized gradient approximation. An asymptotic\ncoefficient, missed by previous derivations, is included in a revised\napproximation. The exchange is also corrected, reducing atomic errors\nconsiderably."
    },
    {
        "anchor": "Iron porphyrin molecules on Cu(001): Influence of adlayers and ligands\n  on the magnetic properties: The structural and magnetic properties of Fe octaethylporphyrin (OEP)\nmolecules on Cu(001) have been investigated by means of density functional\ntheory (DFT) methods and X-ray absorption spectroscopy. The molecules have been\nadsorbed on the bare metal surface and on an oxygen-covered surface, which\nshows a $\\sqrt{2}\\times2\\sqrt{2}R45^{\\circ}$ reconstruction. In order to allow\nfor a direct comparison between magnetic moments obtained from sum-rule\nanalysis and DFT we calculate the dipolar term $7< T_z>$, which is also\nimportant in view of the magnetic anisotropy of the molecule. The measured\nX-ray magnetic circular dichroism shows a strong dependence on the photon\nincidence angle, which we could relate to a huge value of $7< T_z>$, e.g. on\nCu(001) $7< T_z>$ amounts to -2.07\\,\\mbo{} for normal incidence leading to a\nreduction of the effective spin moment $m_s + 7< T_z>$. Calculations have also\nbeen performed to study the influence of possible ligands such as Cl and O\natoms on the magnetic properties of the molecule and the interaction between\nmolecule and surface, because the experimental spectra display a clear\ndependence on the ligand, which is used to stabilize the molecule in the gas\nphase. Both types of ligands weaken the hybridization between surface and\nporphyrin molecule and change the magnetic spin state of the molecule, but the\nchanges in the X-ray absorption are clearly related to residual Cl ligands.",
        "positive": "RF-Sputtering Deposition of Nd1-xsrxcoo3 Oriented Thin Films: In this paper we reported, to the best of our knowledge, the first deposition\nof highly oriented thin films (with thickness of about 90 nm) of NdCoO3 and\nNd0.8Sr0.2CoO3 cobaltites on single-crystalline STO and LAO substrates. Our\ninvestigation has shown that highly oriented single phase thin films of NCO and\nNSCO can be successfully deposited by means of rf-sputtering if the substrates\nis heated at high temperatures (700C); lower substrate temperature has shown to\nlead to multi-phase materials with a low crystallinity degree . LAO substrate\nshowed to give origin to a prefect match of the out-of-plane lattice constant\nof the NSCO target material."
    },
    {
        "anchor": "Is \"L-valine ferric chloride\" a new nonlinear optical material?: We argue that \"L-valine ferric chloride\" crystal reported by Geetha et al\n[Curr. Appl. Phys. 15 (2015) 201-207] is not a new nonlinear optical material\nbut instead a dubious crystal.",
        "positive": "Constrained dynamics of localized excitations causes a non-equilibrium\n  phase transition in an atomistic model of glass formers: Dynamic facilitation theory assumes short-ranged dynamic constraints to be\nthe essential feature of supercooled liquids and draws much of its conclusions\nfrom the study of kinetically constrained models. While deceptively simple,\nthese models predict the existence of trajectories that maintain a high overlap\nwith their initial state over many structural relaxation times. We use\nmolecular dynamics simulations combined with importance sampling in trajectory\nspace to test this prediction through counting long-lived particle\ndisplacements. For observation times longer than the structural relaxation time\nexponential tails emerge in the probability distribution of this number.\nReweighting trajectories towards low mobility corresponds to a phase transition\ninto an inactive phase. While dynamics in these two phases is drastically\ndifferent structural measures show only slight differences. We discuss the\nchoice of dynamic order parameter and give a possible explanation for the\nmicroscopic origin of the effective dynamic constraints."
    },
    {
        "anchor": "Skyrmions with varying size and helicity in composition-spread\n  helimagnetic alloys: The chirality, i.e. left or right handedness, is an important notion in a\nbroad range of science. In condensed matter, this occurs not only in molecular\nor crystal forms but also in magnetic structures. A magnetic skyrmion, a\ntopologically-stable spin vortex structure, as observed in chiral-lattice\nhelimagnets is one such example; the spin swirling direction (skyrmion\nhelicity) should be closely related to the underlying lattice chirality via the\nrelativistic spin-orbit coupling (SOC). Here, we report on the correlation\nbetween skyrmion helicity and crystal chirality as observed by Lorentz\ntransmission electron microscopy (TEM) and convergent-beam electron diffraction\n(CBED) on the composition-spread alloys of helimagnets Mn1-xFexGe over a broad\nrange (x = 0.3 - 1.0) of the composition. The skyrmion lattice constant or the\nskyrmion size shows non-monotonous variation with the composition x,\naccompanying a divergent behavior around x = 0.8, where the correlation between\nmagnetic helicity and crystal chirality is reversed. The underlying mechanism\nis a continuous x-variation of the SOC strength accompanying sign reversal in\nthe metallic alloys. This may offer a promising way to tune the skyrmion size\nand helicity.",
        "positive": "First-order Raman spectra of double perovskites AB$'{1/2}B$''{1/2}O3: First principles computations of Raman intensities were performed for\nperovskite-family compound CaAl$_{1/2}$Nb$_{1/2}$O$_3$ (CAN). This compound\nfeatures 1:1 (NaCl-type) ordering of Al and Nb superimposed onto the $b^-b^-c+$\noctahedral tilting. Raman tensor for CAN was computed using the package for\nfirst-principles computations ABINIT (URL \\underline {http://www.abinit.org}).\nComputations performed for both untilted cubic ($Fm\\bar{3}m$) and tilted\nmonoclinic ($P2_1/n$) CAN structures showed that the strongest Raman lines are\nassociated with the ordering of Al and Nb. The computed spectrum agreed\nqualitatively with the experimental data measured on powder (CAN is available\nin polycrystalline form only). The effect of cation disorder on the Raman\nintensities was considered using phenomenological theory of light scattering in\nthe vicinity of a phase transition. We suggest that, for certain modes, the\ncorresponding Raman intensities depend primarily on the average long range\norder while, for other modes, the intensities are determined by fluctuations of\nthe order parameter."
    },
    {
        "anchor": "Absence of Metallization in Solid Molecular Hydrogen: Being the simplest element with just one electron and proton the electronic\nstructure of the Hydrogen atom is known exactly. However, this does not hold\nfor the complex interplay between them in a solid and in particular not at high\npressure that is known to alter the crystal as well as the electronic\nstructure. Back in 1935 Wigner and Huntington predicted that at very high\npressure solid molecular hydrogen would dissociate and form an atomic solid\nthat is metallic. In spite of intense research efforts the experimental\nrealization, as well as the theoretical determination of the crystal structure\nhas remained elusive. Here we present a computational study showing that the\ndistorted hexagonal P6$_3$/m structure is the most likely candidate for Phase\nIII of solid hydrogen. We find that the pairing structure is very persistent\nand insulating over the whole pressure range, which suggests that metallization\ndue to dissociation may precede eventual bandgap closure. Due to the fact that\nthis not only resolve one of major disagreement between theory and experiment,\nbut also excludes the conjectured existence of phonon-driven superconductivity\nin solid molecular hydrogen, our results involve a complete revision of the\nzero-temperature phase diagram of Phase III.",
        "positive": "A Madelung-Buckingham Model for the Variation of the Cubic Lattice\n  Constant of LixMn2O4 during the charge and discharge of the Lithium-ion\n  Battery: LixMn2O4 is an important cathode material for the Li ion battery. During\nbattery charging, the stoichiometry x varies continuously from 1 to zero and on\ndischarging it varies from zero to one. The cubic lattice constant a of\nLixMn2O4 depends on the value of x and the variation of a with x has important\nconsequences for the battery performance. In this paper, we use a\nMadelung-Buckingham model to study this variation and compare the results with\nexperimental data on LixMn2O4"
    },
    {
        "anchor": "Efficient Energy Transport in an Organic Semiconductor Mediated by\n  Transient Exciton Delocalization: Efficient energy transport is highly desirable for organic semiconductor\n(OSC) devices such as photovoltaics, photodetectors, and photocatalytic\nsystems. However, photo-generated excitons in OSC films mostly occupy highly\nlocalized states over their lifetime. Energy transport is hence thought to be\nmainly mediated by the site-to-site hopping of localized excitons, limiting\nexciton diffusion coefficients to below ~10^{-2} cm^2/s with corresponding\ndiffusion lengths below ~50 nm. Here, using ultrafast optical microscopy\ncombined with non-adiabatic molecular dynamics simulations, we present evidence\nfor a new highly-efficient energy transport regime: transient exciton\ndelocalization, where energy exchange with vibrational modes allows excitons to\ntemporarily re-access spatially extended states under equilibrium conditions.\nIn films of highly-ordered poly(3-hexylthiophene) nanofibers, prepared using\nliving crystallization-driven self-assembly, we show that this enables exciton\ndiffusion constants up to 1.1+-0.1 cm^2/s and diffusion lengths of 300+-50 nm.\nOur results reveal the dynamic interplay between localized and delocalized\nexciton configurations at equilibrium conditions, calling for a re-evaluation\nof the basic picture of exciton dynamics. This establishes new design rules to\nengineer efficient energy transport in OSC films, which will enable new devices\narchitectures not based on restrictive bulk heterojunctions.",
        "positive": "MCAMC: An Advanced Algorithm for Kinetic Monte Carlo Simulations: from\n  Magnetization Switching to Protein Folding: We present the Monte Carlo with Absorbing Markov Chains (MCAMC) method for\nextremely long kinetic Monte Carlo simulations. The MCAMC algorithm does not\nmodify the system dynamics. It is extremely useful for models with discrete\nstate spaces when low-temperature simulations are desired. To illustrate the\nstrengths and limitations of this algorithm we introduce a simple model\ninvolving random walkers on an energy landscape. This simple model has some of\nthe characteristics of protein folding and could also be experimentally\nrealizable in domain motion in nanoscale magnets. We find that even the\nsimplest MCAMC algorithm can speed up calculations by many orders of magnitude.\nMore complicated MCAMC simulations can gain further increases in speed by\norders of magnitude."
    },
    {
        "anchor": "Interstitial segregation has the potential to mitigate liquid metal\n  embrittlement in iron: The embrittlement of metallic alloys by liquid metals leads to catastrophic\nmaterial failure and severely impacts their structural integrity. The weakening\nof grain boundaries by the ingress of liquid metal and preceding segregation in\nthe solid are thought to promote early fracture. However, the potential of\nbalancing between the segregation of cohesion-enhancing interstitial solutes\nand embrittling elements inducing grain boundary decohesion is not understood.\nHere, we unveil the mechanisms of how boron segregation mitigates the\ndetrimental effects of the prime embrittler, zinc, in a $\\Sigma 5\\,[0\\,0\\,1]$\ntilt grain boundary in $\\alpha-$Fe ($4~at.\\%$ Al). Zinc forms nanoscale\nsegregation patterns inducing structurally and compositionally complex grain\nboundary states. Ab-initio simulations reveal that boron hinders zinc\nsegregation and compensates for the zinc induced loss in grain boundary\ncohesion. Our work sheds new light on how interstitial solutes intimately\nmodify grain boundaries, thereby opening pathways to use them as dopants for\npreventing disastrous material failure.",
        "positive": "Elastic Wave Near-Cloaking: Cloaking elastic waves has, in contrast to the cloaking of electromagnetic\nwaves, remained a fundamental challenge: the latter successfully uses the\ninvariance of Maxwell's equations, from which the field of transformational\noptics has emerged, whereas the elastic Navier equations are not invariant\nunder coordinate transformations. Our aim is to overcome this challenge, at\nleast in practical terms, and thereby unlock applications in mechanics,\nultrasound, vibration mitigation, non-destructive evaluation and elastic wave\ncontrol. We achieve near-cloaking by recognising that, despite the lack of\ninvariance, a decoupling into a system of form invariant potential equations\ntogether with a quantifiable approximation, can be used effectively in many\ncases to control the flow of elastodynamic waves. Here, in particular we\n\\rvc{focus} on the efficiency and practicability of the proposed near-cloaking\nwhich is illustrated using carpet cloaks to hide surface defects from incoming\ncompressional and shear in-plane waves and from surface elastic Rayleigh waves."
    },
    {
        "anchor": "Ultrafast modification of the electronic structure of a correlated\n  insulator: A non-trivial balance between Coulomb repulsion and kinematic effects\ndetermines the electronic structure of correlated electron materials. The use\nelectromagnetic fields strong enough to rival these native microscopic\ninteractions allows us to study the electronic response as well as the\ntimescales and energies involved in using quantum effects for possible\napplications. We use element-specific transient x-ray absorption spectroscopy\nand high-harmonic generation to measure the response to ultrashort off-resonant\noptical fields in the prototypical correlated electron insulator NiO.\nSurprisingly, fields of up to 0.22 V/{\\AA} leads to no detectable changes on\nthe correlated Ni 3d-orbitals contrary to previous predictions. A transient\ndirectional charge transfer is uncovered, a behavior that is captured by\nfirst-principles theory. Our results highlight the importance of retardation\neffects in electronic screening, and pinpoints a key challenge in\nfunctionalizing correlated materials for ultrafast device operation.",
        "positive": "Slow Exciton Spin Relaxation in Single Self-Assembled\n  In$_{1-x}$Ga$_x$As/GaAs Quantum Dots: We calculate the acoustic phonon-assisted exciton spin relaxation in single\nself-assembled In$_{1-x}$Ga$_x$As/GaAs quantum dots using an atomic empirical\npseudopotential method. We show that the transition from bright to dark exciton\nstates is induced by Coulomb correlation effects. The exciton spin relaxation\ntime obtained from sophisticated configuration interaction calculations is\napproximately 15--55 $\\mu$s in pure InAs/GaAs QDs and even longer in alloy\ndots. These results contradict previous theoretical and experimental results,\nwhich suggest very short exciton spin times (a few ns), but agree with more\nrecent experiments that suggest that excitons have long spin relaxation times\n($>$ 1 $\\mu$s)."
    },
    {
        "anchor": "Crystal structure, properties and pressure-induced insulator-metal\n  transition in layered kagome chalcogenides: Layered materials with kagome lattice have attracted a lot of attention due\nto the presence of nontrivial topological bands and correlated electronic\nstates with tunability. In this work, we investigate a unique van der Waals\n(vdW) material system, $A_{2}M_{3}X_{4}$ ($A$ = K, Rb, Cs; $M$ = Ni, Pd; $X$ =\nS, Se), where transition metal kagome lattices, chalcogen honeycomb lattices\nand alkali metal triangular lattices coexist simultaneously. A notable feature\nof this material is that each Ni/Pd atom is positioned in the center of four\nchalcogen atoms, forming a local square-planar environment. This crystal field\nenvironment results in a low spin state $S$ = 0 of Ni$^{2+}$/Pd$^{2+}$. A\nsystematic study of the crystal growth, crystal structure, magnetic and\ntransport properties of two representative compounds, Rb$_{2}$Ni$_{3}$S$_{4}$\nand Cs$_{2}$Ni$_{3}$Se$_{4}$, has been carried out on powder and single crystal\nsamples. Both compounds exhibit nonmagnetic $p$-type semiconducting behavior,\nclosely related to the particular chemical environment of Ni$^{2+}$ ions and\nthe alkali metal intercalated vdW structure. Additionally,\nCs$_{2}$Ni$_{3}$Se$_{4}$ undergoes an insulator-metal transition (IMT) in\ntransport measurements under pressure up to 87.10 GPa without any structural\nphase transition, while Rb$_{2}$Ni$_{3}$S$_{4}$ persists in its semiconducting\nbehavior.",
        "positive": "Carrier dependent ferromagnetism in chromium doped topological insulator\n  $Cr_{0.2}Bi_xSb_{1.8-x}Te_3$: Carrier-independent ferromagnetism of chromium doped topological insulator\n$Bi_xSb_{2-x}Te_3$ thin films,which cannot be explained by current theory of\ndilute magnetic semiconductor, has been reported recently. To study if it is\nrelated to the distinctive surface state of topological insulator, we studied\nthe structural, magnetic and transport characters of\n$Cr_{0.2}Bi_xSb_{1.8-x}Te_3$ single crystals. The Curie temperature $T_c$,\nwhich is determined from magnetization and anomalous Hall effect measurements\nby Arrott plots, is found to be proportional to $p^{1/3}$, where p is the hole\ndensity. This fact supports a scenario of RKKY interaction with mean-field\napproximation. This carrier density dependent nature enables tuning and\ncontrolling of the magnetic properties by applying a gate voltage in the future\nscience researches and spintronics applications."
    },
    {
        "anchor": "Local mechanical properties of electrospun fibers correlate to their\n  internal nanostructure: The properties of polymeric nanofibers can be tailored and enhanced by\nproperly managing the structure of the polymeric molecules at the nanoscale.\nAlthough electrospun polymer fibers are increasingly exploited in many\ntechnological applications, their internal nanostructure, determining their\nimproved physical properties, is still poorly investigated and understood.\nHere, we unravel the internal structure of electrospun functional nanofibers\nmade by prototype conjugated polymers. The unique features of near field\noptical measurements are exploited to investigate the nanoscale spatial\nvariation of the polymer density, evidencing the presence of a dense internal\ncore embedded in a less dense polymeric shell. Interestingly, nanoscale mapping\nthe fiber Young's modulus demonstrates that the dense core is stiffer than the\npolymeric, less dense shell. These findings are rationalized by developing a\ntheoretical modeling and simulations of the polymer molecular structural\nevolution during the electrospinning process. This model predicts that the\nstretching of the polymer network induces a contraction towards the jet center\nof the network with a local increase of the polymer density, as observed in the\nsolid structure. The found complex internal structure opens interesting\nperspective for improving and tailoring the molecular morphology and\nmultifunctional electronic and optical properties of polymer fibers.",
        "positive": "Fabrication and Characterization of Two-Dimensional Photonic Crystal\n  Microcavities in Nanocrystalline Diamond: Diamond-based photonic devices offer exceptional opportunity to study cavity\nQED at room temperature. Here we report fabrication and optical\ncharacterization of high quality photonic crystal (PC) microcavities based on\nnanocrystalline diamond. Fundamental modes near the emission wavelength of\nnegatively charged nitrogen-vacancy (N-V) centers (637 nm) with quality factors\n(Qs) as high as 585 were observed. Three-dimensional Finite-Difference\nTime-Domain (FDTD) simulations were carried out and had excellent agreement\nwith experimental results in the values of the mode frequencies. Polarization\nmeasurements of the modes were characterized; their anomalous behavior provides\nimportant insights to scattering loss in these structures."
    },
    {
        "anchor": "Anomalous temperature-dependent spin-valley polarization in monolayer\n  WS$_{2}$: Single layers of transition metal dichalcogenides (TMDs) are direct gap\nsemiconductors with nondegenerate valley indices. An intriguing possibility for\nthese materials is the use of their valley index as an alternate state\nvariable. Several limitations to such a utility include strong, phonon-enabled\nintervalley scattering, as well as multiparticle interactions leading to\nmultiple emission channels. We prepare single-layer WS$_{2}$ such that the\nphotoluminescence is from either the neutral or charged exciton (trion). After\nexcitation with circularly polarized light, the neutral exciton emission has\nzero polarization, however, the trion emission has a large polarization (28%)\nat room temperature. The trion emission also has a unique, non-monotonic\ntemperature dependence that we show is a consequence of the multiparticle\nnature of the trion. This temperature dependence enables us to determine that\ncoulomb assisted intervalley scattering, electron-hole radiative recombination,\nand a 3-particle Auger process are the dominant mechanisms at work in this\nsystem. Because this dependence involves trion systems, one can use gate\nvoltages to modulate the polarization (or intensity) emitted from TMD\nstructures.",
        "positive": "Femtosecond Photoexcited Carrier Dynamics in Reduced Graphene Oxide\n  Suspensions and Films: We report ultrafast response of femtosecond photoexcited carriers in single\nlayer reduced graphene oxide flakes suspended in water as well as few layer\nthick film deposited on indium tin oxide coated glass plate using pump-probe\ndifferential transmission spectroscopy at 790 nm. The carrier relaxation\ndynamics has three components: ~200 fs, 1 to 2 ps, and ~25 ps, all of them\nindependent of pump fluence. It is seen that the second component (1 to 2 ps)\nassigned to the lifetime of hot optical phonons is larger for graphene in\nsuspensions whereas other two time constants are the same for both the\nsuspension and the film. The value of third order nonlinear susceptibility\nestimated from the pump-probe experiments is compared with that obtained from\nthe open aperture Z-scan results for the suspension."
    },
    {
        "anchor": "Nonreciprocal directional dichroism at telecom wavelengths: Magnetoelectrics with ultra-low symmetry and spin-orbit coupling are well\nknown to display a number of remarkable properties including nonreciprocal\ndirectional dichroism. As a polar and chiral magnet, Ni$_3$TeO$_6$ is predicted\nto host this effect in three fundamentally different configurations, although\nonly two have been experimentally verified. Inspired by the opportunity to\nunravel the structure-property relations of such a unique light-matter\ninteraction, we combined magneto-optical spectroscopy and first-principles\ncalculations to reveal nonreciprocity in the toroidal geometry and compared our\nfindings with the chiral configurations. We find that formation of Ni toroidal\nmoments is responsible for the largest effects near 1.1 eV - a tendency that is\ncaptured by our microscopic model and computational implementation. At the same\ntime, we demonstrate deterministic control of nonreciprocal directional\ndichroism in Ni$_3$TeO$_6$ across the entire telecom wavelength range. This\ndiscovery will accelerate the development of photonics applications that take\nadvantage of unusual symmetry characteristics.",
        "positive": "Third-order effect in magnetic small-angle neutron scattering by a\n  spatially inhomogeneous medium: Magnetic small-angle neutron scattering (SANS) is a powerful tool for\ninvestigating nonuniform magnetization structures inside magnetic materials.\nHere, considering a ferromagnetic medium with weakly inhomogeneous uniaxial\nmagnetic anisotropy, saturation magnetization, and exchange stiffness, we\nderive the second-order (in the amplitude of the inhomogeneities) micromagnetic\nsolutions for the equilibrium magnetization textures and compute the\ncorresponding magnetic SANS cross sections up to the next, third order. We find\nthat in the case of perpendicular scattering (the incident neutron beam is\nperpendicular to the applied magnetic field) if twice the cross section along\nthe direction orthogonal to both the field and the neutron beam is subtracted\nfrom the cross section along the field direction, the result has only a\nthird-order contribution (the lower-order terms are canceled). This difference\ndoes not depend on the amplitude of the exchange inhomogeneities and provides a\nseparate gateway for a deeper analysis of the sample's magnetic structure. We\nderive and analyze analytical expressions for the dependence of this\ncombination on the scattering-vector magnitude for the case of spherical\nGaussian inhomogeneities."
    },
    {
        "anchor": "Inelastic Electron Tunneling Spectroscopy at High-Temperatures: Ion conducting materials are critical components of batteries, fuel cells,\nand devices such as memristive switches. Analytical tools are therefore sought\nthat allow the behavior of ions in solids to be monitored and analyzed with\nhigh spatial resolution and in real time. In principle, inelastic tunneling\nspectroscopy offers these capabilities. However, as its spectral resolution is\nlimited by thermal softening of the Fermi-Dirac distribution, tunneling\nspectroscopy is usually constrained to cryogenic temperatures. This constraint\nwould seem to render tunneling spectroscopy useless for studying ions in\nmotion. We report here the first inelastic tunneling spectroscopy studies above\nroom temperature. For these measurements, we have developed\nhigh-temperature-stable tunnel junctions that incorporate within the tunnel\nbarrier ultrathin layers for efficient proton conduction. By analyzing the\nvibrational modes of O-H bonds in BaZrO3-based heterostructures, we demonstrate\nthe detection of protons with a spectral resolution of 20 meV at 400 K (FWHM).\nOverturning the hitherto existing prediction for the spectral resolution limit\nof 186 meV (5.4 kBT at 400 K), this resolution enables high-temperature\ntunneling spectroscopy of ion conductors. With these advances, inelastic\ntunneling spectroscopy constitutes a novel, valuable analytical tool for\nsolid-state ionics.",
        "positive": "Controlled and Continuous Patterning of Organic and Inorganic Materials\n  by Induced Nucleation in an Optical Tweezers: We demonstrate for the first time controlled patterning by inducing\nnucleation of material from a dense aqueous dispersion or solution in an\noptical tweezers. A hot spot is formed on a glass surface by the trapping laser\ndue to which a water vapor bubble is formed causing Gibbs-Marangoni convection\nof material around the bubble. This results in accretion of material around the\nbubble, which eventually nucleates into a crystalline state of the material.\nThe nucleation site, when moved by translating the microscope stage of the\noptical tweezers apparatus, forms a pattern. We have demonstrated the technique\nusing exotic inorganic materials such as soft oxometalates, and organic\nmaterials such as glycine, paracetamol, and a fluorescent dye such as perylene.\nWe have written patterns over lengths of nearly 1 mm at the rate of 1 Hz, with\nbest resolution of about 1 micron. The technique has potential for a wide range\nof applications ranging from solution processed printable electronics to\ncontrolled catalysis."
    },
    {
        "anchor": "Fast recovery of ion-irradiation-induced defects in Ge2Sb2Te5 thin films\n  at room temperature: Phase-change materials serve a broad field of applications ranging from\nnon-volatile electronic memory to optical data storage by providing reversible,\nrepeatable, and rapid switching between amorphous and crystalline states\naccompanied by large changes in the electrical and optical properties. Here, we\ndemonstrate how ion irradiation can be used to tailor disorder in initially\ncrystalline Ge2Sb2Te5 (GST) thin films via the intentional creation of lattice\ndefects. We found that continuous Ar ion irradiation at room temperature of GST\nfilms causes complete amorphization of GST when exceeding 0.6 (for rock-salt\nGST) and 3 (for hexagonal GST) displacements per atom (n_dpa). While the\ntransition from rock-salt to amorphous GST is caused by progressive\namorphization via the accumulation of lattice defects, several transitions\noccur in hexagonal GST upon ion irradiation. In hexagonal GST, the creation of\npoint defects and small defect clusters leads to disordering of intrinsic\nvacancy layers (van der Waals gaps) that drives the electronic metal-insulator\ntransition. Increasing disorder then induces a structural transition from\nhexagonal to rock-salt and then leads to amorphization. Furthermore, we\nobserved different annealing behavior of defects for rock-salt and hexagonal\nGST. The higher amorphization threshold in hexagonal GST compared to rock-salt\nGST is caused by an increased defect-annealing rate, i.e., a higher resistance\nagainst ion-beam-induced disorder. Moreover, we observed that the recovery of\ndefects in GST is on the time scale of seconds or less at room temperature.",
        "positive": "Towards a first-principles chemical engineering: Transport limitations\n  and bistability in in situ CO oxidation at RuO2(110): We present a first-principles based multiscale modeling approach to\nheterogeneous catalysis that integrates first-principles kinetic Monte Carlo\nsimulations of the surface reaction chemistry into a fluid dynamical treatment\nof the macro-scale flow structures in the reactor. The approach is applied to a\nstagnation flow field in front of a single-crystal model catalyst, using the CO\noxidation at RuO2(110) as representative example. Our simulations show how heat\nand mass transfer effects can readily mask the intrinsic reactivity at\ngas-phase conditions typical for modern in situ experiments. For a range of\ngas-phase conditions we furthermore obtain multiple steady-states that arise\nsolely from the coupling of gas-phase transport and surface kinetics. This\nadditional complexity needs to be accounted for when aiming to use dedicated in\nsitu experiments to establish an atomic-scale understanding of the function of\nheterogeneous catalysts at technologically relevant gas-phase conditions."
    },
    {
        "anchor": "Macro deformation twins in single-crystal aluminum: Deformation twinning in pure aluminum has been considered to be a unique\nproperty of nanostructured aluminum. A lingering mystery is whether deformation\ntwinning occurs in coarse-grained or single-crystal aluminum, at scales beyond\nnanotwins. Here, we present the first experimental demonstration of macro\ndeformation twins in single-crystal aluminum formed under ultrahigh strain-rate\n($\\sim$10$^6$ s$^{-1}$), large shear strain (200$\\%$) via dynamic equal channel\nangular pressing. Deformation twinning is rooted in the rate dependences of\ndislocation motion and twinning, which are coupled, complementary processes\nduring severe plastic deformation under ultrahigh strain rates.",
        "positive": "Engineering of Atomic-Scale Flexoelectricity at Grain Boundaries: Flexoelectricity is a type of ubiquitous and prominent electromechanical\ncoupling, pertaining to the response of electrical polarization to mechanical\nstrain gradients while not restricted to the symmetry of materials. However,\nlarge elastic deformation in most solids is usually difficult to achieve and\nthe strain gradient at minuscule is challenging to control. Here we exploit the\nexotic structural inhomogeneity of grain boundary to achieve a huge strain\ngradient (~ 1.2 nm-1) within 3 ~ 4 unit-cells, and thus obtain atomic-scale\nflexoelectric polarization up to ~ 38 {\\mu}C/cm2 at a 24 LaAlO3 grain boundary.\nThe nanoscale flexoelectricity also modifies the electrical activity of grain\nboundaries. Moreover, we prove that it is a general and feasible way to form\nlarge strain gradients at atomic scale by altering the misorientation angles of\ngrain boundaries in different dielectric materials. Thus, engineering of grain\nboundaries provides an effective pathway to achieve tunable flexoelectricity\nand broadens the electromechanical functionalities of non-piezoelectric\nmaterials."
    },
    {
        "anchor": "Is phosphorene with intrinsic defect still an ideal anode material?: The diffusion of Li in electrode materials is key factor to\ncharging/discharging rate capacity of Li-ion battery (LIB). Recently,\ntwo-dimensional phosphorene has been proposed as a very promising electrode\nmaterial due to its ultrafast and directional lithium diffusion, as well as\nlarge energy capacity. Here, on the basis of density functional theory, we\nreport that the intrinsic point defects, including vacancy and stone-wales\ndefects, will block the directional ultrafast diffusion of lithium in\nphosphorene. On the defect-free phosphorene, diffusion of Li along the zigzag\nlattice direction is 1.6 billion times faster than along the armchair lattice\ndirection, and 260 times faster than that in graphite. By introducing intrinsic\nvacancy and stone-wales defect, the diffusion energy barrier of Li along zigzag\nlattice direction increases sharply to the range of 0.17 ~ 0.49 eV, which block\nthe ultrafast migration of lithium along the zigzag lattice direction.\nMeanwhile, the open circuit voltage increases with the emergence of defects,\nwhich is not suitable for anode materials. In addition, the formation energies\nof defects in phosphorene are much lower than those in graphene and silicene\nsheet, therefore, it is highly demanded to generate defect-free phosphorene for\nLIB applications.",
        "positive": "The mechanism of twin thickening and the elastic strain state of TWIP\n  steel nanotwins: A Twinning Induced Plasticity (TWIP) steel with a nominal composition of\nFe-16.4Mn-0.9C-0.5Si-0.05Nb-0.05V was deformed to an engineering strain of 6\\%.\nThe strain around the deformation twins were mapped using the 4D-STEM\ntechnique. Strain mapping showed a large average elastic strain of\napproximately 6\\% in the directions parallel and perpendicular to the twinning\ndirection. However, the large average strain comprised of several hot spots of\neven larger strains of up to 12\\%. These hot spots could be attributed to a\nhigh density of sessile Frank dislocations on the twin boundary and correspond\nto shear stresses of 1--1.5 GPa. The strain and therefore stress fields are\nsignificantly larger than other materials known to twin and are speculated to\nbe responsible for the early thickness saturation of TWIP steel nanotwins. The\nability to keep twins extremely thin helps improve grain fragmentation,\n\\textit{i.e.} the dynamic Hall-Petch effect, and underpins the large\nelongations and strain hardening rates in TWIP steels."
    },
    {
        "anchor": "Comparison of alpha- and beta- tin for lithium, sodium, and magnesium\n  storage: an ab initio study including phonon contributions: We present a comparative ab initio study of Li, Na, and Mg storage in tin,\nincluding phononic effects and phase competition between alpha and beta Sn. Mg\ndoping at low concentration is found to stabilize the beta phase. On the\ncontrary, Li and Na doping is shown to reverse the stability of the phases at\nroom temperature: Li/Na-doped alpha-Sn is more stable than Li/Na-doped beta-Sn\nup to a temperature of around 380/400 K. This may rationalize the formation of\nalpha-Sn upon lithiation and delithiation of beta-Sn anodes reported in\nexperimental studies. The changes in phase stability with Li/Na/Mg doping are\ndirectly related to the intercalation energies of Li/Na/Mg in one phase versus\nthe other: at 300 K, Li/Na is easier intercalated in alpha-Sn (-0.37/-0.08 eV)\nthan in beta-Sn (0.06/0.49 eV), while Mg intercalation energy is, although\npositive (i.e. unfavored intercalation), lower in beta-Sn (0.53 eV) than in\nalpha-Sn (0.66 eV). The temperature effect is found to affect significantly the\nintercalation energy, by up to 0.13 eV at 300 K. Analysis of diffusion barriers\nshows that Li, Na, and Mg diffusion in beta-Sn is anisotropic with migration\nbarriers along the (001) direction (respectively 0.01, 0.22, and 0.07 eV)\nsignificantly lower than those in alpha-Sn (respectively 0.20, 0.52, and 0.40\neV).",
        "positive": "Tetragonality mapping of martensite in a high-carbon steel by EBSD: The locally varying tetragonality in martensite grains of a high-carbon steel\n(1.2 mass percent C) was resolved by electron backscatter diffraction (EBSD)\nwith a spatial resolution in the order of 100nm. Compared to spatially\nintegrating X-ray diffraction, which yielded an average tetragonality of\nc/a=1.05, the EBSD measurements in the scanning electron microscope allowed to\nimage a local variation of the lattice parameter ratio c/a in the range of 1.02\n$\\leq$ c/a $\\leq$ 1.07. The local variation of tetragonality is confirmed by\ntwo different EBSD data analysis approaches based on the fitting of simulated\nto experimental EBSD patterns. The resulting EBSD-based tetragonality maps are\npointing to a complex interaction of carbon concentration and local lattice\ndistortions during the formation process of martensitic structures."
    },
    {
        "anchor": "Diffuse first-order phase transition in NaNbO$_3$:Gd (a report): Dielectric permittivity measurements show that (1-x)NaNbO3-(x)Gd1/3NbO3\ncrystals, at $x=0.09$, exhibit a first order phase transition near 150 C which\nis diffuse over a wide temperature interval. The area of the \\epsilon(T)\nthermal hysteresis loop was found to depend both on the annealing and cooling\ntemperatures. Optical studies in polarized light show the decrease of the\ndomains sizes at this phase transition. The results obtained are fitted\nassuming the space distribution of Curie temperatures.",
        "positive": "First-principles study of As interstitials in GaAs: Convergence,\n  relaxation, and formation energy: Convergence of density-functional supercell calculations for defect formation\nenergies, charge transition levels, localized defect state properties, and\ndefect atomic structure and relaxation is investigated using the arsenic split\ninterstitial in GaAs as an example. Supercells containing up to 217 atoms and a\nvariety of {\\bf k}-space sampling schemes are considered. It is shown that a\ngood description of the localized defect state dispersion and charge state\ntransition levels requires at least a 217-atom supercell, although the defect\nstructure and atomic relaxations can be well converged in a 65-atom cell.\nFormation energies are calculated for the As split interstitial, Ga vacancy,\nand As antisite defects in GaAs, taking into account the dependence upon\nchemical potential and Fermi energy. It is found that equilibrium\nconcentrations of As interstitials will be much lower than equilibrium\nconcentrations of As antisites in As-rich, $n$-type or semi-insulating GaAs."
    },
    {
        "anchor": "Spin relaxation signature of colossal magnetic anisotropy in platinum\n  atomic chains: Recent experimental data demonstrate emerging magnetic order in platinum\natomically thin nanowires. Furthermore, an unusual form of magnetic anisotropy\n-- colossal magnetic anisotropy (CMA) -- was earlier predicted to exist in\natomically thin platinum nanowires. Using spin dynamics simulations based on\nfirst-principles calculations, we here explore the spin dynamics of atomically\nthin platinum wires to reveal the spin relaxation signature of colossal\nmagnetic anisotropy, comparing it with other types of anisotropy such as\nuniaxial magnetic anisotropy (UMA). We find that the CMA alters the spin\nrelaxation process distinctly and, most importantly, causes a large speed-up of\nthe magnetic relaxation compared to uniaxial magnetic anisotropy. The magnetic\nbehavior of the nanowire exhibiting CMA should be possible to identify\nexperimentally at the nanosecond time scale for temperatures below 5 K. This\ntime-scale is accessible in e.g., soft x-ray free electron laser experiments.",
        "positive": "Ni-Au: A testing ground for theories of phase stability: The theory of phase stability in the Ni-Au alloy system is a popular topic\ndue to the large size mismatch between Ni and Au, which makes the effects of\natomic relaxation critical, and also the fact that Ni-Au exhibits a phase\nseparation tendency at low temperatures, but measurements at high-temperature\nshow an ordering-type short-range order. We have clarified the wide disparity\nwhich exists in the previously calculated values of mixing energies and\nthermodynamic properties by computing ``state-of-the-art'' energetics\n(full-potential, fully-relaxed LDA total energies) combined with\n``state-of-the-art'' statistics (k-space cluster expansion with Monte Carlo\nsimulations) for the Ni-Au system. We find: (i) LDA provides accurate mixing\nenergies of disordered Ni_{1-x}Au_x alloys (\\Delta H_{mix} < +100 meV/atom)\nprovided that both atomic relaxation (a ~100 meV/atom effect) and short-range\norder (~25 meV/atom) are taken into account properly. (ii) Previous studies\nusing empirical potentials or approximated LDA methods often underestimate the\nformation energy of ordered compounds, and hence also underestimate the mixing\nenergy of random alloys. (iii) Measured values of the total entropy of mixing\ncombined with calculated values of the configurational entropy demonstrate that\nthe non-configurational entropy in Ni-Au is large, and leads to a significant\nreduction in miscibillity gap temperature. (iv) The calculated short-range\norder agrees well with measurements, and both predict ordering in the\ndisordered phase. (v) Consequently, using inverse Monte Carlo to extract\ninteraction energies from the measured/calculated short-range order in Ni-Au\nwould result in interactions which would produce ordering-type mixing energies,\nin contradiction with both experimental measurements and precise LDA energies."
    },
    {
        "anchor": "Stabilization of helical magnetic structures in thin multilayers: Based on micromagnetic simulations, we report on a novel helical magnetic\nstructure in a soft magnetic film that is sandwiched between and\nexchange-coupled to two hard magnetic layers. Confined between antiparallel\nhard magnetic moments, a helix with a turn of 180$^{\\circ}$ is stable without\nthe presence of an external magnetic field. The magnetic stability is\ndetermined by the energy minimization and is a result of an internal field\ncreated by exchange interaction and anisotropy. Since the internal field stores\nmagnetic energy, the helix can serve as an energy-storing element in spin-based\nnanodevices. Due to the significantly different magnetic resonance frequencies,\nthe ferromagnetic and helical ground states are easy to distinguish in a\nbroadband ferromagnetic resonance experiment.",
        "positive": "Corrosion fatigue crack initiation in ultrafine-grained near-a titanium\n  alloy PT7M prepared by Rotary Swaging: The study focuses on corrosion fatigue processes taking place in an\nultrafine-grained (UFG) near-a-titanium alloy Ti-2.5Al-2.6Zr (Russian\nindustrial name PT7M) used in nuclear engineering. UFG structure formed with\nRotary Swaging is found to increase resistance to corrosion fatigue. Parameters\nof the Basquin's equation are defined and the slope of the fatigue curve\nSa-lg(N) is shown to depend (nonmonotonic dependence) on the UFG alloy\nannealing temperature. This effect can be explained with the patterns of\nmicrostructural evolution in a UFG alloy PT7M during annealing: (1) reduced\ndensity of lattice dislocations, (2) precipitation and dissolution of zirconium\nnanoparticles, (3) release of a''-phase particles causing internal stress\nfields along interphase (a-a'')-boundaries, and (4) intensive grain growth at\nelevated annealing temperatures. It is shown that the fatigue crack closure\neffect manifested as changing internal stress fields determined using XRD\nmethod may be observed in UFG titanium alloys."
    },
    {
        "anchor": "Interstitial diffusion of ion-implanted boron in crystalline silicon: Modeling of the long-range migration of boron interstitials during low\ntemperature annealing of ion-implanted silicon crystals has been carried out.",
        "positive": "Large-scale atomistic simulation of dislocation core structure in\n  face-centered cubic metal with Deep Potential method: The core structure of dislocations is critical to their mobility, cross slip,\nand other plastic behaviors. Atomistic simulation of the core structure is\nlimited by the size of first-principles density functional theory (DFT)\ncalculation and the accuracy of classical molecular dynamics with empirical\ninteratomic potentials. Here, we utilize a Deep Potential (DP) method learned\nfrom DFT calculations to investigate the dislocations of face-centered cubic\ncopper on a large scale and obtain their core structures and energies. The\nvalidity of the DP description of the core structure and elastic strain from\ndislocation is confirmed by a fully discrete Peierls model. Moreover, the DP\nmethod can be further extended easily to dislocations with defects such as\nsurface or vacancy, and our study will pave a way in the large-scale atomistic\nsimulation of dislocation on the DFT level."
    },
    {
        "anchor": "Asymmetric hysteresis of N\u00e9el caps in flux-closure magnetic dots: We investigated with XMCD-PEEM magnetic imaging the magnetization reversal\nprocesses of N\\'eel caps inside Bloch walls in self-assembled, micron-sized\nFe(110) dots with flux-closure magnetic state. In most cases the\nmagnetic-dependent processes are symmetric in field, as expected. However, some\ndots show pronounced asymmetric behaviors. Micromagnetic simulations suggest\nthat the geometrical features (and their asymmetry) of the dots strongly affect\nthe switching mechanism of the N\\'eel caps.",
        "positive": "Dissipative Visco-plastic Deformation in Dynamic Fracture: Tip Blunting\n  and Velocity Selection: Dynamic fracture in a wide class of materials reveals \"fracture energy\"\n$\\Gamma$ much larger than the expected nominal surface energy due to the\nformation of two fresh surfaces. Moreover, the fracture energy depends on the\ncrack velocity, $\\Gamma=\\Gamma(v)$. We show that a simple dynamical theory of\nvisco-plasticity coupled to asymptotic pure linear-elasticity provides a\npossible explanation to the above phenomena. The theory predicts tip blunting\ncharacterized by a dynamically determined crack tip radius of curvature. In\naddition, we demonstrate velocity selection for cracks in fixed-grip strip\ngeometry accompanied by the identification of $\\Gamma$ and its velocity\ndependence."
    },
    {
        "anchor": "Ferromagnetism and suppression of metallic clusters in Fe implanted ZnO\n  - a phenomenon related to defects?: We investigated ZnO(0001) single crystals annealed in high vacuum with\nrespect to their magnetic properties and cluster formation tendency after\nimplant-doping with Fe. While metallic Fe cluster formation is suppressed, no\nevidence for the relevance of the Fe magnetic moment for the observed\nferromagnetism was found. The latter along with the cluster suppression is\ndiscussed with respect to defects in the ZnO host matrix, since the crystalline\nquality of the substrates was lowered due to the preparation as observed by\nx-ray diffraction.",
        "positive": "Role of the rare-earth doping on the multiferroic properties of\n  BaTiO$_3$: First-principles calculation: Ab-initio spin-polarized Density Functional Theory plus U is used to study\nthe electronic and magnetic properties of tetragonal doped barium titanate\n(Ba$_{1-x}$Eu$_x$O$_3$) system for different europium (Eu$^{3+}$)\nconcentrations. For this study, the Projector Augmented Wave (PAW) method and a\nPerdew-Zunger (LSDA) approximation, which has been used for the exchange\ncorrelation energy, have been considered taking into account a supercell model.\nIn this model, the spin polarization as well as the Hubbard's potential have\nbeen used for the correction of the electron-electron Coulomb interactions in\nthe rare-earth ions partially filled f-orbitals. The electronic bands-structure\nreveals that the band-gap energy as well as the dielectric properties decreases\nwith the increase of the doping concentration. On the other hand, the modern\ntheory of polarization also shows that the spontaneous electric polarization\nincreases with the increase of the europium content, whereas the states-density\nreveals ferromagnetic characteristics (with non-zero total magnetization),\nwithout an applied magnetic field, for the Ba$_{1-x}$Eu$_x$O$_3$ system. The\nmagnetic properties also reveal to be strongly dependent on the exchange\ninteraction of the strong localized Eu 4f-states in the crystal lattice."
    },
    {
        "anchor": "Compound-tunable embedding potential method to model local electronic\n  excitations on $f$-element ions in solids: Pilot relativistic coupled cluster\n  study of Ce and Th impurities in yttrium orthophosphate, YPO$_4$: A method to simulate local properties and processes in crystals with\nimpurities via constructing cluster models within the frame of the\ncompound-tunable embedding potential (CTEP) and highly-accurate {\\it ab initio}\nrelativistic molecular-type electronic structure calculations is developed and\napplied to the Ce and Th-doped yttrium orthophosphate crystals, YPO$_4$, having\nxenotime structure. Two embedded cluster models are considered, the \"minimal\"\none, YO$_8$@CTEP$_{\\rm min}$, consisting of the central Y$^{3+}$ cation and its\nfirst coordination sphere of eight O$^{2-}$ anions (i.~e.\\ with broken P--O\nbonds), and its extended counterpart, Y(PO$_4$)$_6$@CTEP$_{\\rm ext}$, implying\nthe full treatment of all atoms of the PO$_4^{3-}$ anions nearest to the\ncentral Y$^{3+}$ cation. CTEP$_{\\rm min,ext}$ denote here the corresponding\ncluster environment described within the CTEP method. The relativistic\nFock-space coupled cluster (FS RCC) theory is applied to the minimal cluster\nmodel to study electronic excitations localized on Ce$^{3+}$ and Th$^{3+}$\nimpurity ions. Calculated transition energies for the cerium-doped xenotime are\nin a good agreement with the available experimental data (mean absolute\ndeviation of ca.0.3 eV for $4f{\\to}5d$ type transitions). For the thorium-doped\ncrystal the picture of electronic states is predicted to be quite complicated,\nthe ground state is expected to be of the $6d$ character. The uncertainty for\nthe excitation energies of thorium-doped xenotime is estimated to be within\n0.35 eV. Radiative lifetimes of excited states are calculated at the FS RCC\nlevel for both doped crystals. The calculated lifetime of the lowest $5d$ state\nof Ce$^{3+}$ differs from the experimentally measured one by no more than\ntwice.",
        "positive": "MPFit: A robust method for fitting atomic resolution images with\n  multiple Gaussian peaks: The standard technique for sub-pixel estimation of atom positions from atomic\nresolution scanning transmission electron microscopy images relies on fitting\nintensity maxima or minima with a two-dimensional Gaussian function. While this\nis a widespread method of measurement, it can be error prone in images with\nnon-zero aberrations, strong intensity differences between adjacent atoms or in\nsituations where the neighboring atom positions approach the resolution limit\nof the microscope. Here we demonstrate mpfit, an atom finding algorithm that\niteratively calculates a series of overlapping two-dimensional Gaussian\nfunctions to fit the experimental dataset and then subsequently uses a subset\nof the calculated Gaussian functions to perform sub-pixel refinement of atom\npositions. Based on both simulated and experimental datasets presented in this\nwork, this approach gives lower errors when compared to the commonly used\nsingle Gaussian peak fitting approach and demonstrates increased robustness\nover a wider range of experimental conditions."
    },
    {
        "anchor": "Mechanisms of spin-polarized current-driven magnetization switching: The mechanisms of the magnetization switching of magnetic multilayers driven\nby a current are studied by including exchange interaction between local\nmoments and spin accumulation of conduction electrons. It is found that this\nexchange interaction leads to two additional terms in the\nLandau-Lifshitz-Gilbert equation: an effective field and a spin torque. Both\nterms are proportional to the transverse spin accumulation and have comparable\nmagnitudes.",
        "positive": "A Computational Study of Yttria-Stabilized Zirconia: I. Using Crystal\n  Chemistry to Search for the Ground State on a Glassy Energy Landscape: Yttria-stabilized zirconia (YSZ), a ZrO2-Y2O3 solid solution that contains a\nlarge population of oxygen vacancies, is widely used in energy and industrial\napplications. Past computational studies correctly predicted the anion\ndiffusivity but not the cation diffusivity, which is important for material\nprocessing and stability. One of the challenges lies in identifying a plausible\nconfiguration akin to the ground state in a glassy landscape. This is unlikely\nto come from random sampling of even a very large sample space, but the odds\nare much improved by incorporating packing preferences revealed by a modest\nsized configurational library established from empirical potential\ncalculations. Ab initio calculations corroborated these preferences, which\nprove remarkably robust extending to the fifth cation-oxygen shell about 8\n{\\AA} away. Yet because of frustration there are still rampant violations of\npacking preferences and charge neutrality in the ground state, and the approach\ntoward it bears a close analogy to glass relaxations. Fast relaxations proceed\nby fast oxygen movement around cations, while slow relaxations require slow\ncation diffusion. The latter is necessarily cooperative because of strong\ncoupling imposed by the long-range packing preferences."
    },
    {
        "anchor": "Band Structure of Topological Insulator BiSbTe1.25Se1.75: We present our angle resolved photoelectron spectroscopy (ARPES) and density\nfunctional theory results on quaternary topological insulator (TI)\nBiSbTe1.25Se1.75 (BSTS) confirming the non-trivial topology of the surface\nstate bands (SSBs) in this compound. We find that the SSBs, which are are\nsensitive to the atomic composition of the terminating surface have a partial\n3D character. Our detailed study of the band bending (BB) effects shows that in\nBSTS the Dirac point (DP) shifts by more than two times compared to that in\nBi2Se3 to reach the saturation. The stronger BB in BSTS could be due to the\ndifference in screening of the surface charges. From momentum density curves\n(MDCs) of the ARPES data we obtained an energy dispersion relation showing the\nwarping strength of the Fermi surface in BSTS to be intermediate between those\nfound in Bi2Se3 and Bi2Te3 and also to be tunable by controlling the ratio of\nchalcogen/pnictogen atoms. Our experiments also reveal that the nature of the\nBB effects are highly sensitive to the exposure of the fresh surface to various\ngas species. These findings have important implications in the tuning of DP in\nTIs for technological applications.",
        "positive": "Recrystallization Characteristics of Catalytic Alloy and Graphite in\n  Diamond Synthesis: We first consider the recrystallization characteristics of catalysis alloy\nand graphite in the process of diamond synthesis under the condition of super\nhigh pressure and high temperature in catalysis method. In the process of\ndiamond synthesis catalysis metal is plastically deformed by increase of\npressure and then recrystallized as increasing the temperature. As catalysis\nmetal is recrystallized, the shape of graphite particle is in spherical shape\nin the region contacting with the catalyst but in any shape in the opposite\nregion. In addition, we calculate the electron charge density distribution and\ncohesive energies of cementite structure using the first principle method to\ninvestigate the reciprocal interaction between transient metal elements and\ncarbon atoms in high-temperature catalyst synthesis. After determination of\nlattice constant parameters, we obtain the cohesive energy by subtracting the\ntotal energy of the crystal from the summation of total energies of atoms\ncomposing the crystal and dividing it by the number of atoms. Therefore, the\neffect of the catalyst on the diamond synthesis is to be analyzed\ntheoretically."
    },
    {
        "anchor": "The First Precise Determination of Graphene Functionalisation by in situ\n  Raman Spectroscopy: We report, for the first time, a comprehensive study involving in situ Raman\nspectroscopy supported by quantum mechanical calculations to exactly monitor\nthe covalent binding to graphene with unprecedented precision. As a model\nreaction we have chosen the hydrogenation of reduced graphite ($KC_8$) with\n$H_2O$ and compared it with the corresponding exposure to $H_2$ and $O_2$. The\nearly stages of graphene hydrogenation are accompanied by the evolution of a\nseries of so far undiscovered D-bands ($D_1$-$D_5$). Using quantum mechanical\ncalculations, we were able to unambiguously assign these bands to distinct\nlattice vibrations in the neighborhood of the covalently bound addend.\nInterestingly, the exposure of $KC_8$ to $H_2$ and $O_2$ didn't cause covalent\nbinding, but intercalation of molecular $H_2$ or partial oxidation,\nrespectively. A combination of $H_2O$ and $O_2$ treatment led to the formation\nof additional hydroxyl (-OH) functionalities. The latter reaction represents a\nvery suitable model for the decomposition of graphenides under ambient\nconditions (hydrogenation and hydroxylation). We have applied this Raman\nanalysis to simulate and satisfactorily characterize a series of additional\ncovalently functionalised graphene derivatives prepared as bulk materials with\ndifferent composition (e.g. degree of functionalisation and the nature of\ncovalent addend) demonstrating the generality of the concept and the\nfundamental value for graphene chemistry.",
        "positive": "Enhanced skyrmion stability due to exchange frustration: Skyrmions are localized, topologically non-trivial spin structures which have\nraised high hopes for future spintronic applications. A key issue is skyrmion\nstability with respect to annihilation into the ferromagnetic state. Energy\nbarriers for this collapse have been calculated taking only nearest neighbor\nexchange interactions into account. Here, we demonstrate that exchange\ninteractions beyond nearest neighbors can be essential to describe stability of\nskyrmionic spin structures. We focus on the prototypical film system\nPd/Fe/Ir(111) and demonstrate that an effective nearest-neighbor exchange or\nmicromagnetic model can only account for equilibrium properties such as the\nskyrmion profile or the zero temperature phase diagram. However, energy\nbarriers and critical fields of skyrmion collapse as well as skyrmion lifetimes\nare drastically underestimated since the energy of the transition state cannot\nbe accurately described. Antiskyrmions are not even metastable. Our work shows\nthat frustration of exchange interactions is a route towards enhanced skyrmion\nstability even in systems with a ferromagnetic ground state."
    },
    {
        "anchor": "Enhancing the Electron Mobility in Si-doped (010) $\u03b2$-Ga$_2$O$_3$\n  films with Low-Temperature Buffer Layers: We demonstrate a new substrate cleaning and buffer growth scheme in\n$\\beta$-Ga$_2$O$_3$ epitaxial thin films using metalorganic vapor phase epitaxy\n(MOVPE). For the channel structure, a low-temperature (LT, 600 $^\\circ$C)\nundoped Ga$_2$O$_3$ buffer is grown followed by transition layers to a\nhigh-temperature (HT, 810 $^\\circ$C) Si-doped Ga$_2$O$_3$ channel layers\nwithout growth interruption. The (010) Ga$_2$O$_3$ Fe-doped substrate cleaning\nuses solvent cleaning followed by an additional HF (49% in water) treatment for\n30 mins before the epilayer growth. This step is shown to compensate the\nparasitic Si channel at the epilayer-substrate interface that originates from\nthe substrate polishing process or contamination from the ambient. SIMS\nanalysis shows the Si peak atomic density at the substrate interface is several\ntimes lower than the Fe atomic density in the substrate - indicating full\ncompensation. The elimination of the parasitic electron channel at the\nepi-substrate interface was also verified by electrical (capacitance-voltage\nprofiling) measurements. In the LT-grown buffer layers, it is seen that the Fe\nforward decay tail from the substrate is very sharp with a decay rate of $\\sim$\n9 nm$/$dec. These channels show record high electron mobility in the range of\n196 - 85 cm$^2$/Vs in unintentionally doped and Si-doped films in the doping\nrange of 2$\\times$10$^{16}$ to 1$\\times$10$^{20}$ cm$^{-3}$. Si delta-doped\nchannels were also grown utilizing this substrate cleaning and the hybrid\nLT-buffers. Record high electron Hall mobility of 110 cm$^2$/Vs was measured\nfor sheet charge density of 9.2$\\times$10$^{12}$ cm$^{-2}$. This substrate\ncleaning combined with the LT-buffer scheme shows the potential of designing\nSi-doped $\\beta$-Ga$_2$O$_3$ channels with exceptional transport properties for\nhigh performance gallium oxide-based electron devices.",
        "positive": "Gigantic Maximum of Nanoscale Noncontact Friction: We report measurements of noncontact friction between surfaces of NbSe$_{2}$\nand SrTiO$_{3}$, and a sharp Pt-Ir tip that is oscillated laterally by a quartz\ntuning fork cantilever. At 4.2 K, the friction coefficients on both the\nmetallic and insulating materials show a giant maximum at the tip-surface\ndistance of several nanometers. The maximum is strongly correlated with an\nincrease in the spring constant of the cantilever. These features can be\nunderstood phenomenologically by a distance-dependent relaxation mechanism with\ndistributed time scales."
    },
    {
        "anchor": "Ten-million-atom electronic structure calculations on the K computer\n  with a massively parallel order-N theory: A massively parallel order-N electronic structure theory was constructed by\nan interdisciplinary research between physics, applied mathematics and computer\nscience. (1) A high parallel efficiency with ten-million-atom nanomaterials was\nrealized on the K computer with upto 98,304 processor cores. The mathematical\nfoundation is a novel linear algebraic algorithm for the generalized shifted\nlinear equation. The calculation was carried out by our code ' ELSES '\n(www.elses.jp) with modelled (tight-binding-form) systems based on ab initio\ncalculations. (2) A post-calculation analysis method, called pi-orbital\ncrystalline orbital Hamiltonian population (pi-COHP) method, is presented,\nsince the method is ideal for huge electronic structure data distributed among\nmassive nodes. The analysis method is demonstrated in an sp2-sp3 nano-composite\ncarbon solid, with an original visualization software 'VisBAR'. The present\nresearch indicates general aspects of computational physics with current or\nnext-generation supercomputers.",
        "positive": "Melting behavior of ultrathin titanium nanowires: The thermal stability and melting behavior of ultrathin titanium nanowires\nwith multi-shell cylindrical structures are studied using molecular dynamic\nsimulation. The melting temperatures of titanium nanowires show remarkable\ndependence on wire sizes and structures. For the nanowire thinner than 1.2 nm,\nthere is no clear characteristic of first-order phase transition during the\nmelting, implying a coexistence of solid and liquid phases due to finite size\neffect. An interesting structural transformation from helical multi-shell\ncylindrical to bulk-like rectangular is observed in the melting process of a\nthicker hexagonal nanowire with 1.7 nm diameter."
    },
    {
        "anchor": "Insights from the quantitative calibration of an elasto-plastic model\n  from a Lennard-Jones atomic glass: We compare the macroscopic and the local plastic behavior of a model\namorphous solid based on two radically different numerical descriptions. On the\none hand, we simulate glass samples by atomistic simulations. On the other, we\nimplement a mesoscale elasto-plastic model based on a solid-mechanics\ndescription. The latter is extended to consider the anisotropy of the yield\nsurface via statistically distributed local and discrete weak planes on which\nshear transformations can be activated. To make the comparison as quantitative\nas possible, we consider the simple case of a quasistatically driven\ntwo-dimensional system in the stationary flow state and compare mechanical\nobservables measured on both models over the same length scales. We show that\nthe macroscale response, including its fluctuations, can be quantitatively\nrecovered for a range of elasto-plastic mesoscale parameters. Using a newly\ndeveloped method that makes it possible to probe the local yield stresses in\natomistic simulations, we calibrate the local mechanical response of the\nelasto-plastic model at different coarse-graining scales. In this case, the\ncalibration shows a qualitative agreement only for an optimized subset of\nmesoscale parameters and for sufficiently coarse probing length scales. This\ncalibration allows us to establish a length scale for the mesoscopic elements\nthat corresponds to an upper bound of the shear transformation size, a key\nphysical parameter in elasto-plastic models. We find that certain properties\nnaturally emerge from the elasto-plastic model. In particular, we show that the\nelasto-plastic model reproduces the Bauschinger effect, namely the\nplasticity-induced anisotropy in the stress-strain response. We discuss the\nsuccesses and failures of our approach, the impact of different model\ningredients and propose future research directions for quantitative multi-scale\nmodels of amorphous plasticity.",
        "positive": "Time-dependent energy absorption changes during ultrafast lattice\n  deformation: The ultrafast time-dependence of the energy absorption of covalent solids\nupon excitation with femtosecond laser pulses is theoretically analyzed. We use\na microscopic theory to describe laser induced structural changes and their\ninfluence on the electronic properties. We show that from the time evolution of\nthe energy absorbed by the system important information on the electronic and\natomic structure during ultrafast phase transitions can be gained. Our results\nreflect how structural changes affect the capability of the system to absorb\nexternal energy."
    },
    {
        "anchor": "Melting of superheated crystals initiates on vacancies: In a large variety of ideal crystals we found that when rapidly migrating\natoms squash or annihilate a neighbouring vacancy and produce a disordered\ncluster, the heat of migration stored in the system exceeds the enthalpy\nincrease required for the coordinating atoms of the vacancy to form a liquid\nphase, i.e. the liquid phase nucleates from vacancies. Furthermore volumetric\nanalysis supports this well. This vacancy-decomposition model provides\nquantitative information on the melting point, the latent heat and the volume\nchange upon melting and hence clarifies the mechanism of melting.",
        "positive": "Designing ABO3 crystal structure with Lennard-Jones interatomic\n  potentials: In this paper, our goal is to design ABO3 crystal structure with simple\ninteratomic Lennard-Jones (LJ) potentials and without setting any initial\nBravais lattice and it is carried out by molecular dynamics (MD) simulation. In\nthe simulation, the equilibrium distances between atoms are determined by LJ\npotentials. For the identification of the microstructure of simulated system,\nwe have calculated the distribution functions of both the angles between one\natom and its nearest neighbors and the distances between atoms and compared the\nresults with those of ideal lattices. The results have clearly shown that we\nhave successfully produced ABO3 crystal structure by MD simulation."
    },
    {
        "anchor": "Quantitative analysis of electronic transport through weakly-coupled\n  metal/organic interfaces: Using single-crystal transistors, we have performed a systematic experimental\nstudy of electronic transport through oxidized copper/rubrene interfaces as a\nfunction of temperature and bias. We find that the measurements can be\nreproduced quantitatively in terms of the thermionic emission theory for\nSchottky diodes, if the effect of the bias-induced barrier lowering is\nincluded. Our analysis emphasizes the role of the coupling between metal and\nmolecules, which in our devices is weak due to the presence of an oxide layer\nat the surface of the copper electrodes.",
        "positive": "Coulomb contribution to Shockley-Read-Hall (SRH) recombination: Defect-mediated nonradiative recombination, known as Shockley-Read-Hall (SRH)\nrecombination is reformulated. The introduced model considers Coulomb\nattraction between charged deep defect and the approaching free carrier,\nshowing that this effect may cause considerable increase of the carrier\nvelocity approaching the recombination center. The effect considerably\nincreases the carrier capture rates. It is demonstrated that in the typical\nsemiconductor device or semiconductor medium, the SRH recombination cannot be\nneglected at low temperatures. The SRH is more effective in the case of low\ndoped semiconductors. Effective screening by mobile carrier density could\nreduce the effect, leading to SRH rate increase."
    },
    {
        "anchor": "Phonon Dispersion Calculation for Binary Alloys Using WDM Approach: The lattice dynamics of AgPd, Ni55Pd45, Ni95Pt05, and Cu0.715Pd0.285\nintermetallic have been investigated using the DFT calculation. The phonon\ndispersions and phonon densities of states along for two symmetry directions\nare calculated by Weighted Dynamical Matrix (WDM) and compared with virtual\ncrystal approximation (VCA), supercell approach, and inelastic neutron\nscattering experimental results. The impact of mass, force-constant\nfluctuation, and Ag concentration on lattice dynamics of AgPd are discussed,\nand a comparison between WDM and Supercell approach is performed. The averaged\nfirst Nearest Neighbor (1NN) force constants between various pairs of atoms in\nthese intermetallic are obtained from the WDM approach. Based on our results,\nthe WDM approach agrees well with the supercell approach, and neutron\nscattering experimental data. VCA overestimates in some cases and\nunderestimates, in other cases, the first-principles frequencies.",
        "positive": "Manifestation of geometric frustration on magnetic and thermodynamic\n  properties of pyrochlores $Sm_2X_2O_7$ (X=Ti, Zr): We present here magnetization, specific heat and Raman studies on\nsingle-crystalline specimens of the first pyrochlore member $Sm_2Ti_2O_7$ of\nthe rare-earth titanate series. Its analogous compound $Sm_2Zr_2O_7$ in the\nrare-earth zirconate series is also investigated in the polycrystalline form.\nThe Sm spins in $Sm_2Ti_2O_7$ remain unordered down to at least T = 0.5 K. The\nabsence of magnetic ordering is attributed to very small values of exchange\n($\\theta_{cw} ~ -0.26 K$) and dipolar interaction ($\\mu_{eff} ~ 0.15 \\mu_B$)\nbetween the $Sm^{3+}$ spins in this pyrochlore. In contrast, the pyrochlore\n$Sm_2Zr_2O_7$ is characterized by a relatively large value of Sm-Sm spin\nexchange ($\\theta_{cw} ~ - 10 K$); however, long-range ordering of the\n$Sm^{3+}$ spins is not established at least down to T = 0.67 K, due to\nfrustration of the $Sm^{3+}$ spins on the pyrochlore lattice. The ground state\nof $Sm^{3+}$ ions in both pyrochlores is a well-isolated Kramer's doublet. The\nhigher-lying crystal field excitations are observed in the low-frequency region\nof the Raman spectra of the two compounds recorded at T = 10 K. At higher\ntemperatures, the magnetic susceptibility of $Sm_2Ti_2O_7$ shows a broad\nmaximum at T = 140 K while that of $Sm_2Zr_2O_7$ changes monotonically. Whereas\n$Sm_2Ti_2O_7$ is a promising candidate for investigating spin-fluctuations on a\nfrustrated lattice as indicated by our data, the properties of $Sm_2Zr_2O_7$\nseem to conform to a conventional scenario where geometrical frustration of the\nspin exclude their long-range ordering."
    },
    {
        "anchor": "A scaling theory of quantum breakdown in solids: We propose a new scaling theory for general quantum breakdown phenomena. We\nshow, taking Landau-Zener type breakdown as a particular example, that the\nbreakdown phenomena can be viewed as a quantum phase transition for which the\nscaling theory is developed. The application of this new scaling theory to\nZener type breakdown in Anderson insulators, and quantum quenching has been\ndiscussed.",
        "positive": "Metastable Kitaev Magnets: Nearly two decades ago, Alexei Kitaev proposed a model for spin-$1/2$\nparticles with bond-directional interactions on a two-dimensional honeycomb\nlattice which had the potential to host a quantum spin-liquid ground state.\nThis work initiated numerous investigations to design and synthesize materials\nthat would physically realize the Kitaev Hamiltonian. The first-generation of\nsuch materials, such as Na$_{2}$IrO$_{3}$, $\\alpha$-Li$_{2}$IrO$_{3}$, and\n$\\alpha$-RuCl$_{3}$, revealed the presence of non-Kitaev interactions such as\nthe Heisenberg and off-diagonal exchange. Both physical pressure and chemical\ndoping were used to tune the relative strength of the Kitaev and competing\ninteractions; however, little progress was made towards achieving a purely\nKitaev system. Here, we review the recent breakthrough in modifying Kitaev\nmagnets via topochemical methods that has led to the second-generation of\nKitaev materials. We show how structural modifications due to the topotactic\nexchange reactions can alter the magnetic interactions in favor of a quantum\nspin-liquid phase."
    },
    {
        "anchor": "Two Dimensional Spin-Polarized Electron Gas at the Oxide Interfaces: The formation of a novel spin-polarized 2D electron gas at the LaMnO$_3$\nmonolayer embedded in SrMnO$_3$ is predicted from the first-principles\ndensity-functional calculations. The La (d) electrons become confined in the\ndirection normal to the interface in the potential well of the La layer,\nserving as a positively-charged layer of electron donors. These electrons\nmediate a ferromagnetic alignment of the Mn t$_{2g}$ spins near the interface\nvia the Anderson-Hasegawa double exchange and become, in turn, spin-polarized\ndue to the internal magnetic fields of the Mn moments.",
        "positive": "Self-assembly of laterally aligned GaAs quantum dot pairs: We report the fabrication of self-assembled, strain-free\nGaAs/Al$_{0.27}$Ga$_{0.73}$As quantum dot pairs which are laterally aligned in\nthe growth plane, utilizing the droplet epitaxy technique and the anisotropic\nsurface potentials of the GaAs (100) surface for the migration of Ga adatoms.\nPhotoluminescence spectra from a single quantum dot pair, consisting of a\ndoublet, have been observed. Finite element energy level calculations of a\nmodel quantum dot pair are also presented."
    },
    {
        "anchor": "Breakdown of Herring's processes in cubic semiconductors for\n  sub-terahertz longitudinal acoustic phonons: In the present work we explain the anomalous behavior of the attenuation of\nthe longitudinal acoustic phonon in GaAs as a function of the phonon energy\n$\\omega$ in the sub-THz domain. These attenuations along the [100] direction\nshow a plateau between 0.6 and 1 GHz at low temperatures. We found an excellent\nagreement between measurements performed by some of us, and new \\textit{ab\ninitio} calculations of third-order anharmonic processes. The formation of the\nplateau is explained by the competition between different phonon-phonon\nscattering processes as Herring's mechanism, which dominates at low\nfrequencies, saturates and disappears. The plateau is shown to be determined by\nthe phononic final-state phase-space available at a given temperature. We\npredict that a change of scattering mechanism should also show up in the\nattenuation of silicon around 1.2-1.7 THz, and argue that the attenuation\nplateau is a general feature of cubic semiconductors.",
        "positive": "A quantitative evaluation of metallic conduction in conjugated polymers: As the periodicity in crystalline materials creates the optimal condition for\nelectronic delocalization, one might expect that in partially crystalline\nconjugated polymers delocalization is impeded by intergrain transport. However,\nfor the best conducting polymers this presumption fails. Delocalization is\nobstructed by interchain rather than intergrain charge transfer and we propose\na model of weakly coupled disordered chains to describe the physics near the\nmetal-insulator transition. Our quantitative calculations match the outcome of\nrecent broad-band optical experiments and provide a consistent explanation of\nmetallic conduction in polymers."
    },
    {
        "anchor": "Martensitic transition and magnetoresistance in a Cu-Al-Mn shape memory\n  alloy. Influence of aging: We have studied the effect of ageing within the miscibility gap on the\nelectric, magnetic and thermodynamic properties of a non-stoichiometric Heusler\nCu-Al-Mn shape-memory alloy, which undergoes a martensitic transition from a\n$bcc$-based ($\\beta$-phase) towards a close-packed structure ($M$-phase).\nNegative magnetoresistance which shows an almost linear dependence on the\nsquare of magnetization with different slopes in the $M$- and $\\beta$-phases,\nwas observed. This magnetoresistive effect has been associated with the\nexistence of Mn-rich clusters with the Cu$_2$AlMn-structure. The effect of an\napplied magnetic field on the martensitic transition has also been studied. The\nentropy change between the $\\beta$- and $M$-phases shows negligible dependence\non the magnetic field but it decreases significantly with annealing time within\nthe miscibility gap. Such a decrease is due to the increasing amount of\nCu$_2$MnAl-rich domains that do not transform martensitically.",
        "positive": "All 2D Heterostructure Tunnel Field Effect Transistors: Impact of Band\n  Alignment and Heterointerface Quality: Van der Waals heterostructures are the ideal material platform for tunnel\nfield effect transistors (TFETs) because a band-to-band tunneling (BTBT)\ndominant current is feasible at room temperature (RT) due to ideal, dangling\nbond free heterointerfaces. However, achieving subthreshold swing (SS) values\nlower than 60 mVdec-1 of the Boltzmann limit is still challenging. In this\nwork, we systematically studied the band alignment and heterointerface quality\nin n-MoS2 channel heterostructure TFETs. By selecting a p+-MoS2 source with a\nsufficiently high doping level, stable gate modulation to a type III band\nalignment was achieved regardless of the number of MoS2 channel layers. For the\ngate stack formation, it was found that the deposition of Al2O3 as the top gate\nintroduces defect states for the generation current under reverse bias, while\nthe integration of an h-BN top gate provides a defect-free, clean interface,\nresulting in the BTBT dominant current even at RT. All 2D heterostructure TFETs\nproduced by combining the type III n-MoS2/p+-MoS2 heterostructure with the h-BN\ntop gate insulator resulted in low SS values at RT."
    },
    {
        "anchor": "On the importance of constrained atomic relaxations in the Nudged\n  Elastic Band calculations of the Peierls barriers of dislocations: We demonstrate that the straightforward application of the Nudged Elastic\nBand (NEB) method does not determine the correct Peierls barrier of 1/2<111>\nscrew dislocations in BCC metals. Although this method guarantees that the\nstates (images) of the system are distributed uniformly along the minimum\nenergy path, it does not imply that the dislocation positions are distributed\nuniformly along this path. In fact, clustering of dislocation positions near\npotential minima occurs which leads to an overestimate of both the slope of the\nPeierls barrier and the Peierls stress. We propose a modification in which the\nNEB method is applied only to a small number of degrees of freedom that\ndetermine the position of the dislocation, while all other coordinates of atoms\nare relaxed by molecular statics as in any atomistic study. This modified NEB\nmethod with relaxations gives the Peierls barrier that increases smoothly with\nthe dislocation position and the corresponding Peierls stress agrees well with\nthat evaluated by the direct application of stress in the atomistic modeling of\nthe dislocation glide.",
        "positive": "$^{13}$C NMR Study on the Charge-Disproportionated Conducting State in\n  the Quasi-Two-Dimensional Organic Conductor $\u03b1$-(BEDT-TTF)$_2$I$_3$: The conducting state of the quasi-two-dimensional organic conductor,\n$\\alpha$-(BEDT-TTF)$_2$I$_3$, at ambient pressure is investigated with $^{13}$C\nNMR measurements, which separate the local electronic states at three\nnonequivalent molecular sites (A, B, and C). The spin susceptibility and\nelectron correlation effect are revealed in a locally resolved manner. While\nthere is no remarkable site-dependence around room temperature, the local spin\nsusceptibility gradually disproportionates among the nonequivalent sites with\ndecreasing temperature. The disproportionation-ratio yields 5:4:6 for A:B:C\nmolecules at 140 K. Distinct site- and temperature-dependences are also\nobserved in the Korringa ratio, $\\mathcal{K}_i \\propto (1/T_{1}T)_iK^{-2}_i$\n($i$ = A, B, and C), which is a measure of the strength and the type of\nelectron correlations. The values of $\\mathcal{K}_i$ point to sizable\nantiferromagnetic spin correlation. We argue the present results in terms of\nthe theoretical prediction of the peculiar site-specific reciprocal-space\n($\\bm{k}$-space) anisotropy on the tilted Dirac cone, and discuss the\n$\\bm{k}$-dependent profiles of the spin susceptibility and electron correlation\non the cone."
    },
    {
        "anchor": "Magnetic interactions in a proposed diluted magnetic semiconductor\n  (Ba$_\\text{1-x}$K$_\\text{x}$)(Zn$_\\text{1-y}$Mn$_\\text{y}$)$_\\text{2}$P$_\\text{2}$: By using first-principles electronic structure calculations, we have studied\nthe magnetic interactions in a proposed BaZn$_2$P$_2$-based diluted magnetic\nsemiconductor (DMS). For a typical compound\nBa(Zn$_{0.944}$Mn$_{0.056}$)$_2$P$_2$ with only spin doping, due to the\nsuperexchange interaction between Mn atoms and the lack of itinerant carriers,\nthe short-range antiferromagnetic coupling dominates. Partially substituting K\natoms for Ba atoms, which introduces itinerant hole carriers into the $p$\norbitals of P atoms so as to link distant Mn moments with the spin-polarized\nhole carriers via the $p$-$d$ hybridization between P and Mn atoms, is very\ncrucial for the appearance of ferromagnetism in the compound. Furthermore,\napplying hydrostatic pressure first enhances and then decreases the\nferromagnetic coupling in\n(Ba$_{0.75}$K$_{0.25}$)(Zn$_{0.944}$Mn$_{0.056}$)$_2$P$_2$ at a turning point\naround 15 GPa, which results from the combined effects of the pressure-induced\nvariations of electron delocalization and $p$-$d$ hybridization. Compared with\nthe BaZn$_2$As$_2$-based DMS, the substitution of P for As can modulate the\nmagnetic coupling effectively. Both the results for BaZn$_2$P$_2$-based and\nBaZn$_2$As$_2$-based DMSs demonstrate that the robust antiferromagnetic (AFM)\ncoupling between the nearest Mn-Mn pairs bridged by anions is harmful to\nimproving the performance of this II-II-V based DMS materials.",
        "positive": "A general forcefield for accurate phonon properties of metal-organic\n  frameworks: We report the development of a forcefield capable of reproducing accurate\nlattice dynamics of metal-organic frameworks. Phonon spectra, thermodynamic and\nmechanical properties, such as free energies, heat capacities and bulk moduli,\nare calculated using the quasi-harmonic approximation to account for anharmonic\nbehaviour due to thermal expansion. Comparison to density functional theory\ncalculations of properties such as Gr$\\mathrm{\\ddot{u}}$neisen parameters, bulk\nmoduli and thermal expansion supports the accuracy of the derived forcefield\nmodel. Material properties are also reported in a full analysis of the lattice\ndynamics of an initial subset of structures including: MOF-5, IRMOF-10, UiO-66,\nUiO-67, NOTT-300, MIL-125, MOF-74 and MOF-650."
    },
    {
        "anchor": "Robust determination of maximally-localized Wannier functions: We propose an algorithm to determine Maximally Localized Wannier Functions\n(MLWFs). This algorithm, based on recent theoretical developments, does not\nrequire any physical input such as initial guesses for the Wannier functions,\nunlike popular schemes based on the projection method. We discuss how the\nprojection method can fail on fine grids when the initial guesses are too far\nfrom MLWFs. We demonstrate that our algorithm is able to find localized Wannier\nfunctions through tests on two-dimensional systems, simplified models of\nsemiconductors, and realistic DFT systems by interfacing with the Wannier90\ncode. We also test our algorithm on the Haldane and Kane-Mele models to examine\nhow it fails in the presence of topological obstructions.",
        "positive": "Electron scattering due to dislocation wall strain field in GaN layers: The effect of edge-type dislocation wall strain field on the Hall mobility in\nn-type epitaxial GaN was theoretically investigated through deformation\npotential within the relaxation time approach. It was found that this channel\nof scattering can play a considerable role in the low-temperature transport at\nthe certain set of the model parameters. The low temperature experimental data\nwere fitted by including this mechanism of scattering along with ionized\nimpurities and charge dislocation ones."
    },
    {
        "anchor": "Treatment and Aging Studies of GaAs(111)B Substrates for van der Waals\n  Chalcogenide Film Growth: GaAs(111)B is a semiconductor substrate widely used in research and\ncommercial fields due to its low cost, mature synthesis technology, and\nexcellent properties for manufacturing electronic devices. It is not only used\nto grow three-dimensional (3D) strongly-bonded materials, but has also been\nused as a substrate for layered, van der Waals (vdW)-bonded chalcogenide film\ngrowth. However, GaAs(111)B wafers cannot be directly used for growing\nepitaxial vdW chalcogenide films for two reasons: (1) the GaAs surface has a\nsubstantial number of dangling bonds that need to be passivated for vdW layers\ngrowth; (2) the substrate surface is covered with a thin epi-ready oxide layer\nwhich must be removed before film growth. In this paper, we optimize the method\nfor deoxidizing GaAs(111)B substrates under a Se overpressure and successfully\ncreate a smooth, deoxidized, and passivated substrate for subsequent growth of\nvdW chalcogenide materials. We demonstrate the benefits of this method for the\ngrowth of vdW chalcogenide thin films using GaSe as a representative of vdW\nchalcogenides. In addition, we find that severely aged substrates have\ndifficulty maintaining a smooth surface during the deoxidation and passivation\nprocess and cause GaSe crystals to nucleate in random shapes and orientations.\nWe describe a method using water droplet testing to determine the age of the\nsubstrate. Finally, X-ray photoelectron spectroscopy (XPS) characterization\nreveals that the natural aging of GaAs(111)B in the air results in an increase\nin surface oxides, Ga2O3 and As2O3, while exposure to ultraviolet (UV)-ozone\nnot only enhances the contents of these two oxides but also generates a new\noxide, As2O5. Our research contributes to expanding the compatibility of\nGaAs(111)B with diverse growth materials and the production of high-quality\nheterostructure devices.",
        "positive": "First-principles calculations of phonon frequencies, lifetimes and\n  spectral functions from weak to strong anharmonicity: the example of\n  palladium hydrides: The variational stochastic self-consistent harmonic approximation is combined\nwith the calculation of third-order anharmonic coefficients within\ndensity-functional perturbation theory and the \"$2n+1$\" theorem to calculate\nanharmonic properties of crystals. It is demonstrated that in the perturbative\nlimit the combination of these two methods yields the perturbative phonon\nlinewidth and frequency shift in a very efficient way, avoiding the explicit\ncalculation of fourth-order anharmonic coefficients. Moreover, it also allows\ncalculating phonon lifetimes and inelastic neutron scattering spectra in solids\nwhere the harmonic approximation breaks down and a non-perturbative approach is\nrequired to deal with anharmonicity. To validate our approach, we calculate the\nanharmonic phonon linewidth in the strongly anharmonic palladium hydrides. We\nshow that due to the large anharmonicity of hydrogen optical modes the\ninelastic neutron scattering spectra are not characterized by a Lorentzian\nline-shape, but by a complex structure including satellite peaks."
    },
    {
        "anchor": "A new view of the spin echo diffusive diffraction on porous structures: Analysis with the characteristic functional of stochastic motion is used for\nthe gradient spin echo measurement of restricted motion to clarify details of\nthe diffraction-like effect in a porous structure. It gives the diffusive\ndiffraction as an interference of spin phase shifts due to the back-flow of\nspins bouncing at the boundaries, when mean displacement of scattered spins is\nequal to the spin phase grating prepared by applied magnetic field gradients.\nThe diffraction patterns convey information about morphology of the surrounding\nmedia at times long enough that opposite boundaries are restricting\ndisplacements. The method explains the dependence of diffraction on the time\nand width of gradient pulses, as observed at the experiments and the\nsimulations. It also enlightens the analysis of transport properties by the\nspin echo, particularly in systems, where the motion is restricted by structure\nor configuration.",
        "positive": "Orbital order induced metal-insulator transition in (La,Ca)MnO3: We present evidence that the insulator to metal transition in (La,Ca)MnO3\nnear x~0.2 is driven by the suppression of coherent Jahn-Teller distortions,\noriginating from d type orbital ordering. The orbital ordered state is\ncharacterised by large long-range Q2 distortions below To*-o'. Above To*-o' we\nfind evidence for coexistence between an orbital-ordered and -disordered state.\nThis behaviour is discussed in terms of electronic phases of an orbital ordered\ninsulating and orbital-disordered metallic states."
    },
    {
        "anchor": "Defect Energy Levels in Density Functional Calculations: Alignment and\n  Band Gap Problem: For materials of varying band gap, we compare energy levels of atomically\nlocalized defects calculated within a semilocal and a hybrid density-functional\nscheme. Since the latter scheme partially relieves the band gap problem, our\nstudy describes how calculated defect levels shift when the band gap approaches\nthe experimental value. When suitably aligned, defect levels obtained from\ntotal-energy differences correspond closely, showing average shifts of at most\n0.2 eV irrespective of band gap. Systematic deviations from ideal alignment\nincrease with the extent of the defect wave function. A guideline for comparing\ncalculated and experimental defect levels is provided.",
        "positive": "Multiple Time Scales in Diffraction Measurements of Diffusive Surface\n  Relaxation: We grew SrTiO3 on SrTiO3 (001) by pulsed laser deposition, using x-ray\nscattering to monitor the growth in real time. The time-resolved small angle\nscattering exhibits a well-defined length scale associated with the spacing\nbetween unit cell high surface features. This length scale imposes a discrete\nspectrum of Fourier components and rate constants upon the diffusion equation\nsolution, evident in multiple exponential relaxation of the \"anti-Bragg\"\ndiffracted intensity. An Arrhenius analysis of measured rate constants confirms\nthat they originate from a single activation energy."
    },
    {
        "anchor": "Determining pressure-temperature phase diagrams of materials: We extend the nested sampling algorithm to simulate materials under periodic\nboundary and constant pressure conditions, and show how it can be used to\ndetermine the complete equilibrium phase diagram, for a given potential energy\nfunction, efficiently and in a highly automated fashion. The only inputs\nrequired are the composition and the desired pressure and temperature ranges,\nin particular, solid-solid phase transitions are recovered without any a priori\nknowledge about the structure of solid phases. We benchmark and showcase the\nalgorithm on the periodic Lennard-Jones system, aluminium and NiTi.",
        "positive": "Coexistence of spin frustration and spin unfrustration induced\n  spontaneous exchange bias in Heusler alloys: The mechanism of spontaneous exchange bias (SEB) and the dominant factor of\nits blocking temperature are still unclear in Heusler alloys. Here, the related\ninvestigations are performed in Mn2Ni1.5Al0.5 Heusler alloys with SEB. The\nresults of both magnetic measurements and first-principles calculations\nconfirmed that spin frustrated and unfrustrated antiferromagnetic (AFM) states\ncoexist there and they have different magnetic anisotropies, which are\nessential for SEB. Based on a series of measurement strategies, we demonstrate\nthat the frustrated AFM state undergoes a first-order magnetic transition to\nthe superferromagnet (SFM) state with the help of an external magnetic field,\nand SFM is retained due to the first-order property of the magnetic transition.\nSEB originates from the interface coupling of multiple sublattices between the\nunfrustrated AFM state and SFM state. By analyzing the Arrott plot using the\nLandau model, we found that the internal field of the system dominates the\nblocking temperature of SEB, which paves the way for improving the blocking\ntemperature."
    },
    {
        "anchor": "Temperature and Pressure Effects on Lattice Properties of Pure C60 Solid: A simple model based on atom-atom potential has been used to calculate\nvarious bulk, structural and thermodynamic properties of pure C_{60} solid by\nincluding implicit anharmonicity. The pressure and temperature dependent\nproperties such as bulk modulus, lattice and orientational structure, thermal\nexpansion, phonon frequency shift, Gruneisen parameters, heat capacity and\nentropy have been calculated and compared with available data. Though results\nfor some of these properties have been calculated earlier, using improved\npotential models to suit C60 solid, this paper ascertains the extent of\nvalidity of a potential used successfully in the past explaining the observed\nproperties of aromatic hydrocarbons. The same potential used without\nmodification does reproduce, barring orientational absolute minimum\nconfiguration, broadly, all the other calculated properties to similar degree\nof accuracy. It thus provides a platform to include additional terms for\ninterpreting properties of doped C60 solids and polymerized C60 systems.",
        "positive": "Spin relaxation in $n$-type GaAs quantum wells with transient spin\n  grating: By solving the kinetic spin Bloch equations, we study the time evolution of\nthe transient spin grating, whose spin polarization varies periodically in real\nspace, confined in (001) GaAs quantum wells. With this study we can investigate\nthe properties of both the spin transport and the spin relaxation at the same\ntime. The Fourier component of the spin signal decays double exponentially with\ntwo decay rates $1/\\tau_+$ and $1/\\tau_-$. In high temperature regime, the\naverage of these two rates varies with the grating wave-vector $q$\nquadratically, i.e., $(1/\\tau_++1/\\tau_-)/2=D_sq^2+1/\\tilde{\\tau}_s$, with\n$D_s$ and $\\tilde{\\tau}_s$ representing the spin diffusion coefficient and the\naverage of the out-of-plane and the in-plane spin relaxation times\nrespectively. $\\tau_{\\pm}$ calculated from our theory are in good agreement\nwith the experimental data by Weber {\\em et al.} [Phys. Rev. Lett. {\\bf 98},\n076604 (2007)]. By comparing $D_s$ with and without the electron-electron\nCoulomb scattering, we calculate the contribution of Coulomb drag to the spin\ndiffusion coefficient. With the transient spin grating result, we further\nreveal the relations among different characteristic parameters such as spin\ndiffusion coefficient $D_s$, spin relaxation time $\\tau_s$, and spin injection\nlength $L_s$. We show that in the presence of the Dresselhaus and/or Rashba\nspin-orbit coupling, the widely used relation $L_s=\\sqrt{D_s\\tau_s}$ is\ngenerally inaccurate and can even be very wrong in some special cases. We\npresent an accurate way to extract the steady-state transport characteristic\nparameters from the transient spin grating signals."
    },
    {
        "anchor": "Spin-orbit coupling effects on spin-dependent inelastic electronic\n  lifetimes in ferromagnets: For the 3d ferromagnets iron, cobalt and nickel we compute the spin-dependent\ninelastic electronic lifetimes due to carrier-carrier Coulomb interaction\nincluding spin-orbit coupling. We find that the spin-dependent\ndensity-of-states at the Fermi energy does not, in general, determine the spin\ndependence of the lifetimes because of the effective spin-flip transitions\nallowed by the spin mixing. The majority and minority electron lifetimes\ncomputed including spin-orbit coupling for these three 3-d ferromagnets do not\ndiffer by more than a factor of 2, and agree with experimental results.",
        "positive": "Atomic-scale mapping and quantification of local Ruddlesden-Popper phase\n  variations: The Ruddlesden-Popper ($A_{n+1}B_{n}\\text{O}_{3n+1}$) compounds are a highly\ntunable class of materials whose functional properties can be dramatically\nimpacted by their structural phase $n$. The negligible energetic differences\nassociated with forming a sample with a single value of $n$ versus a mixture of\n$n$ makes the growth of these materials difficult to control and can lead to\nlocal atomic-scale structural variation arising from small stoichiometric\ndeviations. In this work, we present a Python analysis platform to detect,\nmeasure, and quantify the presence of different $n$-phases based on\natomic-resolution scanning transmission electron microscopy (STEM) images in a\nstatistically rigorous manner. We employ phase analysis on the 002 Bragg peak\nto identify horizontal Ruddlesden-Popper faults which appear as regions of high\npositive compressive strain within the lattice image, allowing us to quantify\nthe local structure. Our semi-automated technique offers statistical advantages\nby considering effects of finite projection thickness, limited fields of view,\nand precise sampling rates. This method retains the real-space distribution of\nlayer variations allowing for a spatial mapping of local $n$-phases, enabling\nboth quantification of intergrowth occurrence as well as qualitative\ndescription of their distribution, opening the door to new insights and levels\nof control over a range of layered materials."
    },
    {
        "anchor": "High Speed Friction Microscopy and Nanoscale Friction Coefficient\n  Mapping: As mechanical devices in the nano/micro length scale are increasingly\nemployed, it is crucial to understand nanoscale friction and wear especially at\ntechnically relevant sliding velocities. Accordingly, a novel technique has\nbeen developed for Friction Coefficient Mapping (FCM), leveraging recent\nadvances in high speed AFM. The technique efficiently acquires friction versus\nforce curves based on a sequence of images at a single location, each with\nincrementally lower loads. As a result, true maps of the coefficient of\nfriction can be uniquely calculated for heterogeneous surfaces. These\nparameters are determined at a scan velocity as fast as 2 mm/s for\nmicrofabricated SiO2 mesas and Au coated pits, yielding results that are\nidentical to traditional speed measurements despite being ~1000 times faster.\nTo demonstrate the upper limit of sliding velocity for the custom setup, the\nfriction properties of mica are reported from 200 {\\mu}m/sec up to 2 cm/sec.\nWhile FCM is applicable to any AFM and scanning speed, quantitative\nnanotribology investigations of heterogeneous sliding or rolling components are\ntherefore uniquely possible, even at realistic velocities for devices such as\nMEMS, biological implants, or data storage systems.",
        "positive": "Switching of Perpendicularly Polarized Nanomagnets with Spin Orbit\n  Torque without an External Magnetic Field by Engineering a Tilted Anisotropy: Spin orbit torque (SOT) provides an efficient way of generating spin current\nthat promises to significantly reduce the current required for switching\nnanomagnets. However, an in-plane current generated SOT cannot\ndeterministically switch a perpendicularly polarized magnet due to symmetry\nreasons. On the other hand, perpendicularly polarized magnets are preferred\nover in-plane magnets for high-density data storage applications due to their\nsignificantly larger thermal stability in ultra-scaled dimensions. Here we show\nthat it is possible switch a perpendicularly polarized magnet by SOT without\nneeding an external magnetic field. This is accomplished by engineering an\nanisotropy in the magnets such that the magnetic easy axis slightly tilts away\nfrom the film-normal. Such a tilted anisotropy breaks the symmetry of the\nproblem and makes it possible to switch the magnet deterministically. Using a\nsimple Ta/CoFeB/MgO/Ta heterostructure, we demonstrate reversible switching of\nthe magnetization by reversing the polarity of the applied current. This\ndemonstration presents a new approach for controlling nanomagnets with spin\norbit torque."
    },
    {
        "anchor": "Creating Continuously Graded Microstructures with Electric Fields via\n  Locally Altering Grain Boundary Complexions: Tailoring microstructures represents a daunting goal in materials science.\nHere, an innovative proposition is to utilize grain boundary (GB) complexions\n(a.k.a. interfacial phases) to manipulate microstructural evolution, which is\nchallenging to control via only temperature and doping. Herein, we use ZnO as a\nmodel system to tailor microstructures using applied electric fields as a new\nknob to control GB structures locally via field-driven stoichiometry (defects)\npolarization. Specifically, continuously graded microstructures are created\nunder applied electric fields. By employing aberration-corrected scanning\ntransmission electron microscopy (AC STEM) in conjunction with density\nfunctional theory (DFT) and ab initio molecular dynamics (AIMD), we discover\ncation-deficient, oxygen-rich GBs near the anode with enhanced GB\ndiffusivities. In addition, the field-driven redistribution of cation vacancies\nis deduced from a defect chemistry model, and subsequently verified by\nspatially resolved photoluminescence spectroscopy. This bulk stoichiometry\npolarization leads to preferential formation of cation-deficient (oxidized) GBs\nnear the anode to gradually promote grain growth towards the anode. This\nmechanism can be utilized to create continuously graded microstructures without\nabnormal grain growth typically observed in prior studies. This study\nexemplifies a case of tailoring microstructural evolution via altering GB\ncomplexions locally with applied electric fields, and it enriches fundamental\nGB science.",
        "positive": "Observation of unconventional van der Waals multiferroics near room\n  temperature: The search for two-dimensional (2D) van der Waals (vdW) multiferroics is an\nexciting yet challenging endeavor. Room-temperature 2D vdW few-layer\nmultiferroic is a much bigger insurmountable obstacle. Here we report the\ndiscovery of an unconventional 2D vdW multiferroic with out-of-plane\nferroelectric polarization and long-range magnetic orders in trilayer NiI2\ndevice from 10 K to 295 K. The evolutions of magnetic domains with magnetic\nfield, and the evolutions between ferroelectric and antiferroelectric phase\nhave been unambiguously observed. More significantly, we realize a robust\nmutual control of magnetism and ferroelectricity at room temperature. The\nmagnetic domains are manipulated by a small voltage ranging from 1 V to 6 V at\n0 T and 295 K. This work opens opportunities for exploring multiferroic physics\nat the limit of few atomic layers."
    },
    {
        "anchor": "Spatially resolved dielectric loss at the Si/SiO$_2$ interface: The Si/SiO$_2$ interface is populated by isolated trap states which modify\nits electronic properties. These traps are of critical interest for the\ndevelopment of semiconductor-based quantum sensors and computers, as well as\nnanoelectronic devices. Here, we study the electric susceptibility of the\nSi/SiO$_2$ interface with nm spatial resolution using frequency-modulated\natomic force microscopy to measure a patterned dopant delta-layer buried 2 nm\nbeneath the silicon native oxide interface. We show that surface charge\norganization timescales, which range from 1-150 ns, increase significantly\naround interfacial states. We conclude that dielectric loss under time-varying\ngate biases at MHz and sub-MHz frequencies in metal-insulator-semiconductor\ncapacitor device architectures is highly spatially heterogeneous over nm length\nscales.",
        "positive": "Evolution of topological order in Xe films on a quasicrystal surface: We report results of the first computer simulation studies of a physically\nadsorbed gas on a quasicrystalline surface, Xe on decagonal Al-Ni-Co. The grand\ncanonical Monte Carlo method is employed, using a semi-empirical gas-surface\ninteraction, based on conventional combining rules, and the usual Lennard-Jones\nXe-Xe interaction. The resulting adsorption isotherms and calculated structures\nare consistent with the results of LEED experimental data. The evolution of the\nbulk film begins in the second layer, while the low coverage behavior is\nepitaxial. This transition from 5-fold to 6-fold ordering is temperature\ndependent, occurring earlier (at lower coverage) for the higher temperatures."
    },
    {
        "anchor": "Fused borophenes: a new family of superhard materials: The search of new superhard materials has received a strong impulse by\nindustrial demands for low-cost alternatives to diamond and $c$-BN, such as\nmetal borides. In this Letter we introduce a new family of superhard materials,\n\"fused borophenes\", containing 2D boron layers which are interlinked to form a\n3D network. These materials, identified through a high-throughput scan of\nBxC1-x structures, exhibit Vicker's hardnesses comparable to those of the best\ncommercial metal borides. Due to their low formation enthalpies, fused\nborophenes could be synthesized by high-temperature methods, starting from\nappropriate precursors, or through quenching of high-pressure phases.",
        "positive": "Inelastic electron tunneling spectroscopy of nanoporous gold films: We investigated the localized electronic properties of nanoporous gold films\nby using an ultra-high vacuum scanning tunneling microscope at low temperature\n(4.2 K). Second derivative scanning tunneling spectroscopy shows the plasmon\npeaks of the nanoporous gold films, which are excited by inelastic tunneling\nelectrons. We propose that the nanorod model is appropriate for nanoporous gold\nstudies at the nanometer-scale. These results are supported by a 3D electron\ntomography analysis and theoretical calculations of nanoporous gold with\nellipsoid shape."
    },
    {
        "anchor": "Effect of dispersion interactions on the properties of LiF in condensed\n  phases: Classical molecular dynamics simulations are performed on LiF in the\nframework of the polarizable ion model. The overlap-repulsion and polarization\nterms of the interaction potential are derived on a purely non empirical,\nfirst-principles basis. For the dispersion, three cases are considered: a first\none in which the dispersion parameters are set to zero and two others in which\nthey are included, with different parameterizations. Various thermodynamic,\nstructural and dynamic properties are calculated for the solid and liquid\nphases. The melting temperature is also obtained by direct coexistence\nsimulations of the liquid and solid phases. Dispersion interactions appear to\nhave an important effect on the density of both phases and on the melting\npoint, although the liquid properties are not affected when simulations are\nperformed in the NVT ensemble at the experimental density.",
        "positive": "Synthesis methods of graphitic carbon nitride: a superior photocatalyst: In recent years, conjugated polymers such as graphitic Carbon Nitride\n(g-C3N4) attracts major attention to the researchers for the harnessing of\nrenewable energy and environmental remediation through photocatalytic water\nsplitting. Its moderate electronic band gap structure helps to absorb large\nspectrum of abundant solar radiation for the generation of hydrogen, a high\ndensity chemical energy source, by water splitting method. Its outstanding\nphysicochemical stability makes it a reliable energy conversion material.\nAnother key attribute to the researchers is the simple way of synthesizing\npristine g-C3N4 and its nanocomposite structures modified with metallic and\nnon-metallic materials. g-C3N4 can be synthesized in both chemical and physical\nprocess. In this work, the superiority in structural, optical and\nphotocatalytic property observed in physically developed g-C3N4 over chemically\nsynthesized g-C3N4 has been discussed and based on such studies, a suitable\nsynthesis method has been proposed."
    },
    {
        "anchor": "The (11-22) and (-12-16) twinning modes modelled by obliquity correction\n  of a (58deg, a+2b) prototype stretch twin: The {11-22} and {11-26} twinning modes were recently put in evidence by\nOstapovets et al. (Phil. Mag, 2017)and interpreted as {101-2}-{101-2}\ndouble-twins formed by a simultaneous action of two twinning shears. We propose\nanother interpretation in which the twinning modes result from a one-step\nmechanism based on the same (58deg, a+2b) prototype stretch twin. . The two\ntwins differ from the prototype twin by their obliquity correction. The results\nare compared with the classical theory of twinning and with Westlake-Rosenbaum\nmodel of {11-22} twinning. An unconventional twinning mode recently discovered\nin a magnesium single crystal based on the same prototype twin will be the\nsubject of a separate publication.",
        "positive": "Effects of morphology on phonons of nanoscopic silver grains: The morphology of nanoscopic Ag grains significantly affects the phonons.\nAtomistic simulations show that realistic nanograin models display complex\nvibrational properties. (1) Single-crystalline grains. Nearly-pure torsional\nand radial phonons appear at low frequencies. For low-energy, faceted models,\nthe breathing mode and acoustic gap (lowest frequency) are about 10% lower than\npredicted by elasticity theory (ET) for a continuum sphere of the same volume.\nThe sharp edges and the atomic lattice split the ET-acoustic-gap quintet into a\ndoublet and triplet. The surface protrusions associated with nearly spherical,\nhigh-energy models produce a smaller acoustic gap and a higher vibrational\ndensity of states (DOS) at frequencies \\nu<2 THz. (2) Twined icosahedra. In\ncontrast to the single-crystal case, the inherent strain produce a larger\nacoustic gap, while the core atoms yield a DOS tail extending beyond the\nhighest frequency of single-crystalline grains. (3) Mark's decahedra, in\ncontrast to (1) and (2), do not have a breathing mode; although twined and\nstrained, do not exhibit a high-frequency tail in the DOS. (4) Irregular\nnanograins. Grain boundaries and surface disorder yield non-degenerate phonon\nfrequencies, and significantly smaller acoustic gap. Only these nanograins\nexhibit a low-frequency \\nu^2 DOS in the interval 1-2 THz."
    },
    {
        "anchor": "Correlation in transport coefficients of hole-doped CuRhO$_2$ single\n  crystals: To clarify the origin of the nontrivial thermoelectric properties observed in\nthe delafossite oxide CuRhO$_2$ polycrystals, we have performed the systematic\ntransport measurements on the single-crystalline CuRhO$_2$ samples. In the\nparent compound, we find a pronounced peak structure due to a phonon-drag\neffect in the temperature dependence of the Seebeck coefficient, which is also\nconfirmed by the size effect experiments. In the Mg-substituted crystals, in\ncontrast to the results of the polycrystals, both the resistivity and the\nSeebeck coefficient decrease with increasing Mg content $y$. In particular, the\ncoefficient $A$ for the $T^2$ term of the resistivity and the $T$-linear\ncoefficient for the Seebeck coefficient at low temperatures are well described\nwithin a simple relationship expected for metals, which is also applicable to\nthe correlated materials with low carrier densities.",
        "positive": "Spin-wave dynamics controlled by tunable ac magnonic crystal: The magnonic crystal, which has a spatial modulation wave vector $q$, couples\nthe spin wave with wave vector $k$ to the one with wave vector $k-q$. For a\nconventional magnonic crystal with direct current (dc) supply, the spin waves\naround $q/2$ are resonantly coupled to the waves near $-q/2$, and a band gap is\nopened at $k=\\pm q/2$. If instead of the dc current the magnonic crystal is\nsupplied with an alternating current (ac), then the band gap is \\emph{shifted}\nto $k$ satisfying $|\\omega_{s}(k)-\\omega_{s}(k-q)|=\\omega_{ac}$; here\n$\\omega_{s}(k)$ is the dispersion of the spin wave, while $\\omega_{ac}$ is the\nfrequency of the ac modulation. The resulting gap in the case of the ac\nmagnonic crystal is the half of the one caused by the dc with the same\namplitude of modulation. The time evolution of the resonantly coupled spin\nwaves controlled by properly suited ac pulses can be well interpreted as the\nmotion on a Bloch sphere. The tunability of the ac magnonic crystal broadens\nthe perspective of spin-wave computing."
    },
    {
        "anchor": "Nanoscale ferroelastic twins formed in strained LaCoO3 films: The coexistence and coupling of ferroelasticity and magnetic ordering in a\nsingle material offers a great opportunity to realize novel devices with\nmultiple tuning knobs. Complex oxides are a particularly promising class of\nmaterials to find multiferroic interactions as they often possess rich phase\ndiagrams and the interactions are very sensitive to external perturbations.\nStill, there are very few examples of these systems. Here we report the\nobservation of twinning domains in ferroelastic LaCoO3 epitaxial thin films and\ntheir geometric control of structural symmetry that are intimately linked to\nthe material electronic and magnetic states. A unidirectional structural\nmodulation is achieved by selective choice of substrates possessing two-fold\nrotational symmetry. This modulation perturbs the crystal field splitting\nenergy, leading to unexpected in plane anisotropy of orbital configuration and\nmagnetization. These findings demonstrate the utilization of structural\nmodulation to control multiferroic interactions and may enable a great\npotential for stimulation of exotic phenomena through artificial domain\nengineering.",
        "positive": "Rashba-Dresselhaus spin-splitting in the bulk ferroelectric oxide\n  BiAlO$_3$: It has been recently suggested that the coexistence of ferroelectricity and\nRashba-like spin-splitting effects due to spin-orbit coupling in a single\nmaterial may allow for a non-volatile electric control of spin degrees of\nfreedom. In the present work, we compared the structural and ferroelectric\nproperties of tetragonal and rhombohedral phases of ferroelectric BiAlO$_3$ by\nmeans of density-functional calculations. In both phases, we carefully\ninvestigated Rashba and Dresselhaus effects, giving rise to spin-splitting in\ntheir bulk electronic structure, particularly near the conduction band minimum,\nsupplementing our first-principles results with an effective $ k\\cdot p$ model\nanalysis. The full reversal of the spin texture with ferroelectric polarization\nswitching was also predicted. BiAlO$_3$ can therefore be considered as the\nfirst known oxide to exhibit a coexistence of ferroelectricity and\nRashba-Dresselhaus effects."
    },
    {
        "anchor": "The Structural and Electronic Properties of Pristine and Doped\n  Polythiophene: Periodic Versus Molecular Calculations: Based on density functional theory calculations, the structural and\nelectronic properties of polythiophene in periodic and oligomer forms have been\ninvestigated. In particular, the effects of Li or Cl adsorption onto a\nmonolayer and Li or Cl-intercalation into bulk or bilayer polythiophene are\naddressed using periodic calculations. The binding energy of Li or Cl adsorbed\nbulk or bilayer polythiophene is significantly larger than for the monolayer.\nThe trends in the binding energy as a function of adsorbent remain the same for\nboth the periodic and molecular cases. The band gap or HOMO-LUMO gap and charge\ntransfer are analysed. In addition, for the bulk or bilayer, different kinds of\nstacking have been considered. It is found that the parallel bulk or bilayer\nstructure is energetically favorable compared to flipping the second layer by\n180$^\\circ$. This has been considered for both the periodic and oligomer forms.\nMoreover, for Li adsorption, polarons are found to be more stable than\nbipolarons, while the situation is opposite for Cl adsorption. The detailed\nanalysis of the present study will be useful for understanding the structural\nproperties and the tuneability of the electronic states, which is an important\nstep to construct polythiophene based electronic devices.",
        "positive": "Hidden quantum mirage by negative refraction in semiconductor P-N\n  junctions: We predict a novel quantum interference based on the negative refraction\nacross a semiconductor P-N junction: with a local pump on one side of the\njunction, the response of a local probe on the other side behaves as if the\ndisturbance emanates not from the pump but instead from its mirror image about\nthe junction. This phenomenon is guaranteed by translational invariance of the\nsystem and matching of Fermi surfaces of the constituent materials, thus it is\nrobust against other details of the junction (e.g., junction width, potential\nprofile, and even disorder). The recently fabricated P-N junctions in 2D\nsemiconductors provide ideal platforms to explore this phenomenon and its\napplications to dramatically enhance charge and spin transport as well as\ncarrier-mediated long-range correlation."
    },
    {
        "anchor": "Physical properties of KMgBi single crystals: KMgBi single crystals are grown by using the Bi flux successfully. KMgBi\nshows semiconducting behavior with a metal-semiconductor transition at high\ntemperature region and a resistivity plateau at low temperature region,\nsuggesting KMgBi could be a topological insulator with a very small band gap.\nMoreover, KMgBi exhibits multiband feature with strong temperature dependence\nof carrier concentrations and mobilities.",
        "positive": "Adsorption on a Surface with Varying Properties: We propose a self-consistent model taking into account variations in\nadsorption properties of the adsorbent surface in the process of\nadsorption--desorption of molecules of gas on it. We introduce a dimensionless\ncoupling parameter that characterizes the interaction of an adsorbed molecule\nwith polarized medium. It is established that the system can be bistable if the\ncoupling parameter is greater than a critical value and the concentration of\ngas belongs to a certain interval. We show that the adsorption isotherms\nobtained within the framework of the proposed model essentially differ from the\nLangmuir isotherms and establish that the Zeldovich hysteresis is possible. The\nkinetics of the surface coverage is analyzed in detail. We show that taking\naccount of variations in adsorption properties of the surface in the process of\nadsorption--desorption leads to new phenomena: a \"quasistationary\" state in the\ncase of the overdamped approximation and self-oscillations of the system in the\ngeneral case."
    },
    {
        "anchor": "Skyrmion ground state and gyration of skyrmions in magnetic nanodisks\n  without the Dzyaloshinsky-Moriya interaction: We show by micromagnetic simulations that spontaneous skyrmion ground state\ncan exist in Co/Ru/Co nanodisks without the Dzyaloshinsky-Moriya interaction\n(DMI), which can remain stable in the applied magnetic field along +z direction\neven up to 0.44 T. The guiding center ($R_x$,$R_y$) of skyrmion defined by the\nmoments of the topological density presents a novel gyration with a star-like\ntrajectory in a pulsed magnetic field and a hexagonal trajectory after the\nfield is switched off, which is different from that of vortex or bubble. One of\nthe coupled skyrmions could move without an external magnetic field, but only\ninduced by the motion of the other one due to strong inter-layer magnetostatic\ninteractions. This work sheds light on how novel skyrmions can be discovered in\nvarious (not limited to magnetic) systems with competing energies and\ncontributes to the understanding of the dynamical properties of skyrmion.",
        "positive": "A Structural Phase Transition in Ca3Co4O9 Associated with Enhanced High\n  Temperature Thermoelectric Properties: Temperature dependent electrical resistivity, crystal structure and heat\ncapacity measurements reveal a resistivity drop and metal to semiconductor\ntransition corresponding to first order structural phase transition near 400 K\nin Ca3Co4O9. The lattice parameter c varies smoothly with increasing\ntemperature, while anomalies in the a, b1 and b2 lattice parameters occur at ~\n400 K. Both Ca2CoO3 and CoO2 layers become distorted above ~ 400 K associated\nwith the metal to semiconductor transport behavior change. Resistivity and heat\ncapacity measurements as a function of temperature under magnetic field\nindicates low spin contribution to this transition. Reduced resistivity\nassociated with this first order phase transition from metallic to\nsemiconducting behavior enhances the thermoelectric properties at high\ntemperatures and points to the metal to semiconductor transition as a mechanism\nfor improved ZT in high temperature thermoelectric oxides."
    },
    {
        "anchor": "Origin of the spectral linewidth in non linear oscillators based on MgO\n  tunnel junctions: We demonstrate the strong impact of the oscillator agility on the line\nbroadening by studying spin transfer induced microwave emission in MgO-based\ntunnel junctions with current. The linewidth is almost not affected by\ndecreasing the temperature. At very low currents, a strong enhancement of the\nlinewidth at low temperature is attributed to an increase of the non linearity,\nprobably due to the field-like torque. Finally we evidence that the noise is\nnot dominated by thermal fluctuations but rather by the chaotization of the\nmagnetization system induced by the spin transfer torque.",
        "positive": "YIG thickness and frequency dependence of the spin-charge current\n  conversion in YIG/Pt systems: We report the frequency dependence of the spin current emission in a hybrid\nferrimagnetic insulator/normal metal system as function of the insulating layer\nthickness. The system is based on a yttrium iron garnet (YIG) film [0.2, 1, and\n3 \\mu m] grown by liquid-phase-epitaxy coupled with a spin current detector of\nplatinum [6 nm]. A strong YIG thickness dependence of the efficiency of the\nspin pumping has been observed. The highest conversion factor \\Delta V/P_{abs}\nhas been demonstrated for the thinner YIG (1.79 and 0.55 mV/mW^{-1} at 2.5 and\n10 GHz, respectively) which presents an interest for the realisation of\nYIG-based devices. A strong YIG thickness dependence of the efficiency of the\nspin pumping has been also observed and we demonstrate the threshold frequency\ndependence of the three-magnon splitting process."
    },
    {
        "anchor": "Multi-objective Generative Design of Three-Dimensional Composite\n  Materials: Composite materials with 3D architectures are desirable in a variety of\napplications for the capability of tailoring their properties to meet multiple\nfunctional requirements. By the arrangement of materials' internal components,\nstructure design is of great significance in tuning the properties of the\ncomposites. However, most of the composite structures are proposed by empirical\ndesigns following existing patterns. Hindered by the complexity of 3D\nstructures, it is hard to extract customized structures with multiple desired\nproperties from large design space. Here we report a multi-objective driven\nWasserstein generative adversarial network (MDWGAN) to implement inverse\ndesigns of 3D composite structures according to given geometrical, structural\nand mechanical requirements. Our framework consists a GAN based network which\ngenerates 3D composite structures possessing with similar geometrical and\nstructural features to the target dataset. Besides, multiple objectives are\nintroduced to our framework for the control of mechanical property and isotropy\nof the composites. Real time calculation of the properties in training\niterations is achieved by an accurate surrogate model. We constructed a small\nand concise dataset to illustrate our framework. With multiple objectives\ncombined by their weight, and the 3D-GAN act as a soft constraint, our\nframework is proved to be capable of tuning the properties of the generated\ncomposites in multiple aspects, while keeping the selected features of\ndifferent kinds of structures. The feasibility on small dataset and potential\nscalability on objectives of other properties make our work a novel, effective\napproach to provide fast, experience free composite structure designs for\nvarious functional materials.",
        "positive": "Comment on ``Elastic Stabilization of a Single-Domain Ferroelectric\n  State in Nanoscale Capacitors and Tunnel Junctions\" [N.A. Pertsev and H.\n  Kohlstedt, Phys. Rev. Lett. 98, 257603 (2007).]: In a recent Letter [N.A. Pertsev and H. Kohlstedt, Phys. Rev. Lett. 98,\n257603 (2007)] the authors claim that \"even nanoscale capacitors and tunnel\njunctions may have out of plane polarization sufficient for memory\napplications.\" Here we show in an elementary way that this conclusion is not\nsubstantiated by their calculations and that they should have come to the\nopposite conclusion within their approximations."
    },
    {
        "anchor": "Angle-Dependent van Hove Singularities and Their Breakdown in Twisted\n  Graphene Bilayers: The creation of van der Waals heterostructures based on a graphene monolayer\nand other two-dimensional crystals has attracted great interest because atomic\nregistry of the two-dimensional crystals can modify the electronic spectra and\nproperties of graphene. Twisted graphene bilayer can be viewed as a special van\nder Waals structure composed of two mutual misoriented graphene layers, where\nthe sublayer graphene not only plays the role of a substrate, but also acts as\nan equivalent role as the top graphene layer in the structure. Here we report\nthe electronic spectra of slightly twisted graphene bilayers studied by\nscanning tunneling microscopy and spectroscopy. Our experiment demonstrates\nthat twist-induced van Hove singularities are ubiquitously present for rotation\nangles theta less than about 3.5o, corresponding to moir\\'e-pattern periods D\nlonger than 4 nm. However, they totally vanish for theta > 5.5o (D < 2.5 nm).\nSuch a behavior indicates that the continuum models, which capture\nmoir\\'e-pattern periodicity more accurately at small rotation angles, are no\nlonger applicable at large rotation angles.",
        "positive": "Atomic mechanism of phase transition between metallic and semiconducting\n  MoS2 single-layers: Structural transformation between metallic (1T) and semiconducting (2H)\nphases of single-layered MoS2 was systematically investigated by an in situ\nSTEM with atomic precision. The 1T/2H phase transition is comprised of S and/or\nMo atomic-plane glides, and requires an intermediate phase ({\\alpha}-phase) as\nan indispensable precursor. Migration of two kinds of boundaries ({\\beta} and\n{\\gamma}-boundaries) is also found to be responsible for the growth of the\nsecond phase. The 1T phase can be intentionally introduced in the 2H matrix by\nusing a high dose of incident electron beam during heating the MoS2\nsingle-layers up to 400~700{\\deg}C in high vacuum and indeed controllable in\nsize. This work may lead to the possible fabrication of composite nano-devices\nmade of local domains with distinct electronic properties."
    },
    {
        "anchor": "Development of simulation package for atomic processes of\n  ultra-large-scale system based on electronic structure theory: An early-stage version of simulation package is developed for electronic\nstructure calculation and dynamics of atom process in large-scale systems,\nparticularly, nm-scale or 10nm-scale systems. We adopted the Extensible Markup\nLanguage (XML)-style in the input and the output of our simulation code, and\ndeveloped some modeling and analysis tools for dynamical simulations of atomic\nprocesses. GaAs bulk system was calculated to demonstrate that the present code\ncan handle systems with more than one atom specie.",
        "positive": "Antiferroelectric Oxide Thin-Films: Fundamentals, Properties, and\n  Applications: Antiferroelectrics have received blooming interests because of a wide range\nof potential applications in energy storage, solid-state cooling, thermal\nswitch, transducer, actuation, and memory devices. Many of those applications\nare the most prospective in thin film form. The antiferroelectric ordering in\nthin films is highly sensitive to a rich set of factors, such as lattice\nstrain, film thickness, surface and interface effects as well as film\nstoichiometry. To unlock the full potential of these materials and design\nhigh-quality thin films for functional devices, a comprehensive and systematic\nunderstanding of their behavior is essential. In conjunction with the necessary\nfundamental background of antiferroelectrics, we review recent progress on\nvarious antiferroelectric oxide thin films, the key parameters that trigger\ntheir phase transition and the device applications that rely on the robust\nresponses to electric, thermal, and optical stimuli. Current challenges and\nfuture perspectives highlight new and emerging research directions in this\nfield. It is hoped that this review can boost the development of\nantiferroelectric thin-film materials and device design, stimulating more\nresearchers to explore the unknowns together."
    },
    {
        "anchor": "Topological band structure transitions in honeycomb antimonene as\n  function of buckling: The electronic band topology of monolayer $\\beta$-Sb (antimonene) is studied\nfrom the flat honeycomb to the equilibrium buckled structure using\nfirst-principles calculations and analyzed using a tight-binding model and low\nenergy Hamiltonians. In flat monolayer Sb, the Fermi level occurs near the\nintersection of two warped Dirac cones, one associated with the $p_z$-orbitals,\nand one with the $\\{p_x,p_y\\}$-orbitals. The differently oriented threefold\nwarping of these two cones leads to an unusually shaped nodal line, which leads\nto anisotropic in-plane transport properties and goniopolarity. A slight\nbuckling opens a gap along the nodal line except at six remaining Dirac points,\nprotected by symmetry. Under increasing buckling, pairs of Dirac points of\nopposite winding number annihilate at a critical buckling angle. At a second\ncritical angle, the remaining Dirac points disappear when the band structure\nbecomes a trivial semiconductor. Spin-orbit coupling and edge states are\ndiscussed.",
        "positive": "Magnetism and Verwey transition in magnetite nanoparticles in thin\n  polymer film: Magnetic and structural properties of magnetite nanoparticles stabilized in\npolyvinyl-alcohol thin films are investigated by using X-ray diffraction (XRD),\ntransmission electron microscopy (TEM), electron paramagnetic resonance (EPR)\nand static magnetometry techniques. The nanoparticles have well-defined\ncrystallinity, and are superparamagnetic at room temperature. Their size\ndistribution is characterized by the distinct log-normal law (with average\ndiameters near 5-7 nm) and slight maximum near 70-80 nm. The EPR spectra and\nstatic magnetization data demonstrated pronounced anomalies in the interval\nbetween 130 K (corresponding to Verwey transition) and 200 K. The experimental\ndata obtained can be understood on the basis of the half-metallic electronic\nstructure, complex temperature behavior of the magnetic anisotropy, along with\neffects of \"weak magnetic-electron\" sublattice of magnetite."
    },
    {
        "anchor": "Large Room Temperature Bulk DNP of $^{13}$C via P1 Centers in Diamond: We use microwave-induced dynamic nuclear polarization (DNP) of the\nsubstitutional nitrogen defects (P1 centers) in diamond to hyperpolarize bulk\n$^{13}$C nuclei in both single crystal and powder samples at room temperature\nat 3.34 T. The large ($>100$-fold) enhancements demonstrated correspond to a\ngreater than 10,000 fold improvement in terms of signal averaging of the 1\\%\nabundant $^{13}$C spins. The DNP was performed using low-power solid state\nsources under static (non-spinning) conditions. The DNP spectrum (DNP\nenhancement as a function of microwave frequency) of diamond powder shows\nfeatures that broadly correlate with the EPR spectrum. A well-defined negative\nOverhauser peak and two solid effect peaks are observed for the central\n($m_I=0$) manifold of the $^{14}$N spins. Previous low temperature measurements\nin diamond had measured a positive Overhauser enhancement in this manifold.\nFrequency-chirped millimeter-wave excitation of the electron spins is seen to\nsignificantly improve the enhancements for the two outer nuclear spin manifolds\n($m_I = \\pm 1$) and to blur some of the sharper features associated with the\ncentral manifolds. The outer lines are best fit using a combination of the\ncross effect and a truncated cross effect -- which is known to mimic features\nof an Overhauser effect. Similar features are also observed in experiments on\nsingle crystal samples. The observation of all of these mechanisms in a single\nmaterial system under the same experimental conditions is likely due to the\nsignificant heterogeneity of the high pressure, high temperature (HPHT) type Ib\ndiamond samples used. Large room temperature DNP enhancements at fields above a\nfew Tesla enable spectroscopic studies with better chemical shift resolution\nunder ambient conditions.",
        "positive": "Coexistence of open and closed gallery spaces in intercalation compounds: A series of molybdenum disulfide intercalation compounds was prepared to\nstudy the effect of varying loadings of the samples with intercalated\nmolecules. The molecules, (5,7,7,12,14,14-hexamethyl-1,4,8,11-\ntetraazacyclotetradeca-4,11-diene) macrocycles, occupy the gallery spaces\nbetween the MoS2 layers in a single layer. The samples were characterized by\nthermogravimetry, wide angle X-ray scattering, scanning electron microscopy and\ntransmission electron microscopy (TEM). TEM images reveal the layer stacking as\nthe filling of the gallery spaces with macrocycles increases gradually up to\none monolayer per gallery space. Fourier transforms of these images are in\nexcellent agreement with the X-ray scattering of the bulk compound. X-ray\nscattering by these compounds was simulated by evaluating the Debye sum for\nweighted averages of model particles that have sequences of open and closed\ngallery spaces. Open and closed gallery spaces coexist in the samples with less\nthan one monolayer of intercalated molecules per gallery space. The fraction of\nopen gallery spaces increases with macrocycle loading, from zero for restacked\nMoS2 without macrocycles to one for a fully intercalated compound. The sequence\nof open and closed spaces is approximately random, and the MoS2 layers stack\nwith the same orientation but with random lateral shifts. The binding enthalpy\nof the macrocycles in the gallery spaces is about 14 meV."
    },
    {
        "anchor": "Negative permeability in magnetostatics and its experimental\n  demonstration: The control of magnetic fields, essential for our science and technology, is\ncurrently achieved by magnetic materials with positive permeability, including\nferromagnetic, paramagnetic, and diamagnetic types. Here we introduce materials\nwith negative static permeability as a new paradigm for manipulating magnetic\nfields. As a first step, we extend the solutions of Maxwell magnetostatic\nequations to include negative-permeability values. The understanding of these\nnew solutions allow us to devise a negative-permeability material as a suitably\ntailored set of currents arranged in space, overcoming the fact that passive\nmaterials with negative permeability do no exist in magnetostatics. We confirm\nthe theory by experimentally creating a spherical shell that emulates a\nnegative-permeability material in a uniform magnetic field. Our results open\nnew possibilities for creating and manipulating magnetic fields, which can be\nuseful for practical applications.",
        "positive": "Magnetic properties of FeCo nanoclusters on Cu(100): We present ab-initio calculations of the magnetic moments and magnetic\nanisotropy energies of small FeCo clusters of varying composition on top of a\nCu(100) substrate. Three different cluster layouts have been considered, namely\n2x2, 3x3 and cross-like pentamer clusters. The ratio of Co atoms with respect\nto the total number in a chosen cluster (``concentration'') was varied and all\npossible arrangements of the atomic species were taken into account.\nCalculations have been performed fully relativistically using the embedded\ncluster technique in conjunction with the screened Korringa-Kohn-Rostoker\nmethod and the magnetocrysergy depend on the position they occupy in a\nparticular cluster and on the type and the number of nearest-neighbors. The MAE\nfor the 2x2 and 3x3 clusters varies with respect to the ``concentration'' of Co\natoms in the same manner as the corresponding monolayer case, whereas the\npentamer clusters show a slightly different behavior. Furthermore, for the\nclusters with an easy axis along a direction in the surface plane, the MAE\nshows a significant angular dependence."
    },
    {
        "anchor": "Infrared emissivity spectroscopy of a soda-lime silicate glass up to the\n  melt: The short-range structure of an iron doped soda-lime glass was investigated\nby infrared emissivity spectroscopy from room temperature up to the melt.\nQuantitative information on the distribution of the Q^n tetrahedral units was\nobtained by fitting the emissivity spectra using a dielectric function model\n(DFM). The DFM is based on causal Gaussian bands, associated with the\nstretching motions of the silicate tetrahedra. The changes in the absorption\nmodes are related to the activation of a dynamical disorder that continuously\nincreases with temperature. The obtained Q^n speciation at room temperature is\nin good agreement with the magic-angle spinning nuclear magnetic resonance (MAS\nNMR) study. The distribution of the tetrahedral species undergoes slight\nchanges with temperature, except during glass crystallization where Q^4 units\nincreases, with a slight augmentation of Q^2 and Q^4 units in the melt. These\nresults demonstrate the potentiality of infrared spectroscopy in the\nquantitative analysis of the polymerization degree of glasses and melts.",
        "positive": "Polycaprolactone/graphite nanoplates composite nanopapers: Nanopapers based on graphene and related materials were recently proposed for\napplication in heat spreader applications. To overcome typical limitations in\nbrittleness of such materials, this work addressed the combination of graphite\nnanoplatelets (GNP) with a soft, tough and crystalline polymer, acting as an\nefficient binder between nanoplates. With this aim, polycaprolactone (PCL) was\nselected and exploited in this paper. The crystalline organization of PCL\nwithin the nanopaper was studied to investigate the effect of polymer\nconfinement between GNP. Thermomechanical properties were studied by dynamic\nmechanical analyses at variable temperature and creep measurements at high\ntemperature, demonstrating superior resistance at temperatures well above PCL\nmelting. Finally, the heat conduction properties on the nanopapers were\nevaluated, resulting in outstanding values above 150 Wm-1K-1."
    },
    {
        "anchor": "Field-Effect Transistor Based on MoSi$_2$N$_4$ and WSi$_2$N$_4$\n  Monolayers Under Biaxial Strain: A Computational Study of the Electronic\n  Properties: The electronic properties of a field-effect transistor with two different\nstructures of MoSi$_2$N$_4$ and WSi$_2$N$_4$ monolayers as the channel material\nin the presence of biaxial strain are investigated. The band structures show\nthat these compounds are semiconductors with an indirect bandgap. Their band\ngaps can be adjusted by applying in-plane biaxial strain. In the following, the\nvariation of the energies of the valleys and corresponding effective masses\nwith respect to the strain are explored. Finally, the strained MoSi$_2$N$_4$ or\nWSi$_2$N$_4$ are used as the channel of a p-type FET and the corresponding\ncurrent-voltage characteristic is explored. The results show this FET has an\nI$\\mathrm{_{ON}}$/I$\\mathrm{_{OFF}}$ ratio larger than $\\mathrm{10^6}$ and\nsubthreshold swing in the range of 96-98 mV/dec. The\nI$\\mathrm{_{ON}}$/I$\\mathrm{_{OFF}}$ ratio of these compounds with respect to\nstrain are compared.",
        "positive": "Magnetic coupling at ferromagnetic rare earth / transition-metal\n  interfaces: A comprehensive study: Thin film magnetic heterostructures with competing interfacial coupling and\nZeeman energy pro- vide a fertile ground to study phase transition between\ndifferent equilibrium states as a function of external magnetic field and\ntemperature. A rare-earth (RE) / transition metal (TM) ferro- magnetic\nmultilayer is a classic example where the magnetic state is determined by a\ncompetition between the Zeeman energy and antiferromagnetic interfacial\nexchange coupling energy. Techno- logically, such structures offer the\npossibility to engineer the macroscopic magnetic response by tuning the\nmicroscopic interactions between the layers. We have performed an exhaustive\nstudy of a nickel/gadolinium system by using the element-specific measurement\ntechnique x-ray magnetic circular dichroism, and determined the full magnetic\nstate diagrams as a function of temperature and magnetic layer thickness. We\nexplain our result based on a modified Stoner-Wohlfarth formal- ism and provide\nevidence of a thickness-dependent phase transition to a magnetic fan state\nwhich is critical in understanding magnetoresistance effects in RE/TM systems.\nThe results provide im- portant insight for spintronics and superconducting\nspintronics where engineering tunable magnetic inhomogeneity is key for certain\napplications."
    },
    {
        "anchor": "Strong Spreading in a Droplet Flow for Low-Dimensional Nanostructures\n  Growth: We report an in situ transmission electron microscopy observation of an\nindium droplet flowing on a silicon nitride membrane with a coating layer of\nhydrogenated amorphous silicon (a-Si:H), with the production of in-plane c-Si\nnanowire in its trail. We observe that the droplet strongly spreads on the\na-Si:H coated surface while it dewets from the c-Si NW. This in situ\nobservation, combined with the geometric analysis of such liquid-solid systems,\npresents nice consistency with de Gennes theoretic prediction of the droplet\nhydrodynamics steered by reactive spreading, where the wettability gradient for\nthe droplet flowing is maintained by a progressively autophobic process due to\nthe droplet mediated crystallization of a-Si:H. Interestingly, we record\ntemperature dependent evolution of the droplet-nanowire interface, which leads\nthe droplet break-up, self-turning and the nanoflake-to-nanowire transition. We\nelucidate these rich nanofluidic phenomena by a model based on the\nheterogeneous nucleation governed reactive spreading.",
        "positive": "Finite element analysis of ion-implanted diamond surface swelling: We present experimental results and numerical Finite Element analysis to\ndescribe surface swelling due to the creation of buried graphite-like\ninclusions in diamond substrates subjected to MeV ion implantation. Numerical\npredictions are compared to experimental data for MeV proton and helium\nimplantations, performed with scanning ion microbeams. Swelling values are\nmeasured with white light interferometric profilometry in both cases.\nSimulations are based on a model which accounts for the through-the-thickness\nvariation of mechanical parameters in the material, as a function of ion type,\nfluence and energy. Surface deformation profiles and internal stress\ndistributions are analyzed and numerical results are seen to adequately fit\nexperimental data. Results allow us to draw conclusions on structural damage\nmechanisms in diamond for different MeV ion implantations."
    },
    {
        "anchor": "Electrical transport properties of atomically thin WSe2 using\n  perpendicular magnetic anisotropy metal contacts: Tungsten diselenide, WSe2 shows excellent properties and become very\npromising material among two dimensional semiconductors. Wide band gap and\nlarge spin-orbit coupling along with naturally lacking inversion symmetry in\nthe monolayer WSe2 make it efficient material for spintronics, optoelectronics\nand valleytronics applications. In this work, we report electrical transport\nproperties of monolayer WSe2 based field effect transistor with most needed\nmultilayer Co/Pt ferromagnetic electrodes exhibiting perpendicular magnetic\nanisotropy. We studied contacts behaviour by performing I-V curve measurements\nand estimating Schottky barrier heights (SBHs). SBHs estimated from\nexperimental data are found to be comparatively small, without using any tunnel\nbarrier. This work expands the current understanding of WSe2 based devices and\ngives insight into the electrical behaviour of Co/Pt metal contacts, which can\nopen great possibilities for spintronic/valleytronic applications.",
        "positive": "Compensated ferrimagnetic tetragonal Heusler thin films for\n  antiferromagnetic spintronics: In recent years, antiferromagnetic spintronics has received much attention\nsince ideal antiferromagnets do not produce stray fields and are much more\nstable to external magnetic fields compared to materials with net\nmagnetization. Akin to antiferromagnets, compensated ferrimagnets have zero net\nmagnetization but have the potential for large spin-polarization and strong out\nof plane magnetic anisotropy, and, hence, are ideal candidates for high density\nmemory applications. Here, we demonstrate that a fully compensated magnetic\nstate with a tunable magnetic anisotropy is realized in Mn-Pt-Ga based\ntetragonal Heusler thin films. Furthermore, we show that a bilayer formed from\na fully compensated and a partially compensated Mn-Pt-Ga layer, exhibits a\nlarge interfacial exchange bias up to room temperature. The present work\nestablishes a novel design principle for spintronic devices that are formed\nfrom materials with similar elemental compositions and nearly identical crystal\nand electronic structures. Such devices are of significant practical value due\nto their improved properties such as thermal stability. The flexible nature of\nHeusler materials to achieve tunable magnetizations, and anisotropies within\nclosely matched materials provides a new direction to the growing field of\nantiferromagnetic spintronics."
    },
    {
        "anchor": "Observation of optical absorption correlated with surface state of\n  topological insulator: We performed broadband optical transmission measurements of Bi2Se3 and\nIn-doped Bi(1-x)In(x)2Se3 thin films, where in the latter the spin-orbit\ncoupling (SOC) strength can be tuned by introducing In. Drude and interband\ntransitions exhibit In-dependent changes that are consistent with evolution\nfrom metallic (x=0) to insulating (x=1) nature of the end compounds. Most\nnotably, an optical absorption peak located at hw=1eV in Bi2Se3 is completely\nquenched at x=0.06, the critical concentration where the phase transition from\nTI into non-TI takes place. For this x, the surface state (SS) is vanished from\nthe band structure as well. The correlation between the 1eV optical peak and\nthe SS in the x-dependences suggests that the peak is associated with the SS.\nWe further show that when Bi2Se3 is electrically gated, the 1eV-peak becomes\nstronger(weaker) when electron is depleted from (accumulated into) the SS.\nThese observations combined together demonstrate that under the hw=1eV\nillumination electron is excited from a bulk band into the topological surface\nband of Bi2Se3. The optical population of surface band is of significant\nimportance not only for fundamental study but also for TI-based optoelectronic\ndevice application.",
        "positive": "Signature effects of spin clustering and distribution of spin couplings\n  on magnetization behaviour in Ni-Fe-Mo and Ni-Fe-W alloys: The spontaneous magnetization as a function of temperature is investigated\nfor a number of disordered Ni-Fe-Mo and Ni-Fe-W alloys using superconducting\nquantum interference device magnetometry, with a focus on the low-T behavior as\nwell as the critical exponents associated with the magnetic phase transition.\nWhile the low-T magnetization is found to be well described by Bloch's T^{3/2}\nlaw, an extraordinary enhancement of the spin-wave parameter B and the reduced\ncoefficient B_{3/2}=BT_C ^{3/2} are observed with increasing Fe dilution as\ncompared to conventional 3d ferromagnets, whereas the critical amplitudes are\nfound to decrease systematically. Recent locally self-consistent calculations\nof finite-temperature spin dynamics in a generic diluted magnet provide an\nunderstanding in terms of two distinct energy scales associated with weakly\ncoupled bulk spins in the FM matrix and strongly coupled cluster spins. In view\nof similar behaviour observed in diluted magnetic semiconductors and other\nferromagnetic alloys, it is proposed that these distinctive features\ncorresponding to the three important temperature regimes provide macroscopic\nindicators of signature effects of spin clustering on magnetization behaviour\nin disordered ferromagnets."
    },
    {
        "anchor": "Thermoelectric properties of half-Heusler $\\mathrm{ZrNiPb}$ by using\n  first principles calculations: We investigate electronic structures and thermoelectric properties of recent\nsynthetic half-Heusler $\\mathrm{ZrNiPb}$ by using generalized gradient\napproximation (GGA) and GGA plus spin-orbit coupling (GGA+SOC). Calculated\nresults show that $\\mathrm{ZrNiPb}$ is a indirect-gap semiconductor. Within the\nconstant scattering time approximation, semi-classic transport coefficients are\nperformed through solving Boltzmann transport equations. It is found that the\nSOC has more obvious influence on power factor in p-type doping than in n-type\ndoping, leading to a detrimental effect in p-type doping. These can be\nexplained by considering the SOC influences on the valence bands and conduction\nbands near the Fermi level. The lattice thermal conductivity as a function of\ntemperature is calculated, and the corresponding lattice thermal conductivity\nis 14.5 $\\mathrm{W m^{-1} K^{-1}}$ at room temperature. By comparing the\nexperimental transport coefficients with calculated ones, the scattering time\nis attained for 0.333 $\\times$ $10^{-14}$ s. Finally, the thermoelectric figure\nof merit $ZT$ can be attained, and the $ZT$ value can be as high as 0.30 at\nhigh temperature by choosing appropriate doping level. It is possible to reduce\nlattice thermal conductivity by point defects and boundaries, and make\nhalf-Heusler $\\mathrm{ZrNiPb}$ become potential candidate for efficient\nthermoelectricity.",
        "positive": "Examining the Effects of Irradiation Temperature on Defect Generation\n  and the Nature of Dislocation Loops: Unlike the vast amount of irradiated material data that exists for stainless\nsteel internals from LWRs, with high fast neutron flux and an irradiation\ntemperature of~330oC, the CANDU reactor is unique with a high thermal spectrum\nstainless steel components peripheral to the core. In particular, the CANDU\ndesign contains an austenitic stainless steel calandria vessel, which contains\nthe heavy water moderator at a temperature of 60-80oC. This article explores\nthe effects of low (60-80oC) and moderate (300-360oC) irradiation temperature\non irradiation induced defects and defect sinks, both in terms of\nmicrostructure and mechanical properties of Grade 304L stainless steel,\nirradiated with 3 MeV protons. State-of-the-art microscopy has been applied to\ncharacterize the irradiation defects, and nano-indentation performed to provide\na link with the mechanical properties. It is hypothesized that the interstitial\ntype of loops that develop is highly temperature dependent, and the formation\nof the defect loops is strongly linked with the amount of radiation induced\nsegregation."
    },
    {
        "anchor": "A review of uranium-based thin films: Thin films based on silicon and transition-metal elements dominate the\nsemiconducting industry and are ubiquitous in all modern devices. Films have\nalso been produced in the rare-earth series of elements for both research and\nspecialized applications. Thin films of uranium and uranium dioxide were\nfabricated in the 1960s and 1970s, but there was little sustained effort until\nthe early 2000s. Significant programmes started at Oxford University\n(transferring to Bristol University in 2011), and Los Alamos National\nLaboratory (LANL) in New Mexico, USA. In this review we cover the work that has\nbeen published over the last ~20 years with these materials. Important\nbreakthroughs occurred with the fabrication of epitaxial thin films of\ninitially uranium metal and UO2, but more recently of many other uranium\ncompounds and alloys. These have led to a number of different experiments that\nare reviewed, as well as some important trends. The interaction with the\nsubstrate leads to differing strain and hence changes in properties. An\nimportant advantage is that epitaxial films can often be made of materials that\nare impossible to produce as bulk single crystals. Examples are U3O8, U2N3 and\nalloys of U-Mo, which form in a modified bcc structure. Epitaxial films may\nalso be used in applied research. They represent excellent surfaces, and it is\nat the surfaces that most of the important reactions occur in the nuclear fuel\ncycle. For example, the fuel-cladding interactions, and the dissolution of fuel\nby water in the long-term storage of spent fuel. To conclude, we discuss\npossible future prospects, examples include bilayers containing uranium for\nspintronics, and superlattices that could be used in heterostructures. Such\napplications will require a more detailed knowledge of the interface\ninteractions in these systems, and this is an important direction for future\nresearch.",
        "positive": "Eliminating the Perovskite Solar Cell Manufacturing Bottleneck via\n  High-Speed Flexography: Perovskite solar cells have potential to deliver terawatt-scale power via\nlow-cost manufacturing. However, scaling is limited by slow, high-temperature\nannealing of the inorganic transport layers and the lack of reliable,\nlarge-area methods for depositing thin (< 30 nm) charge transport layers\n(CTLs). We present a method for scaling ultrathin NiOx hole transport layers\n(HTLs) by pairing high-speed (60 m/min) flexographic printing with rapidly\nannealed sol-gel inks to achieve the fastest reported process for fabrication\nof inorganic CTLs for perovskites. By engineering precursor rheology for rapid\nfilm-leveling, NiOx HTLs were printed with high uniformity and ultralow pinhole\ndensities resulting in photovoltaic performance exceeding that of spin-coated\ndevices. Integrating these printed transport layers in planar inverted PSCs\nallows rapid fabrication of high efficiency (PCE > 15%) Cs(x)FA(1-x)PbI solar\ncells with improved short circuit currents (Jsc) of 22.4 mA/cm2. Rapid\nannealing of the HTL accelerates total processing time by 60X, while\nmaintaining the required balance of optoelectronic properties and the chemical\ncomposition for effective hole collection. These results build an improved\nunderstanding of ultrathin NiOx and reveal opportunities to enhance device\nperformance via scalable manufacturing of inorganic CTLs."
    },
    {
        "anchor": "Sublimable complexes with spin switching: Chemical design, processing as\n  thin films and integration in graphene-based devices: Among the different types of switchable molecular compounds, sublimable\nFe(II) SCO molecules provide a suitable platform to develop smart devices that\nrespond to external stimuli. Here we report the synthesis, crystallographic\nstructure and magnetic properties of three new neutral Fe(II) SCO molecules\nbelonging to the {Fe[H2B(pz)2]2(L)} family with bidentate-alpha-diimine ligands\nL = 3-(pyridin-2-yl)-[1,2,3]triazolo[1,5-a]pyridine (tzpy),\n5,5,6,6-tetrahydro-4H,4H-2,2-bi(1,3-thiazine) (btz) and\n4,4,5,5-tetrahydro-2,2-bithiazole (bt) (1, 2 and 3, respectively), as well as\ntwo solvated forms of 1 and 3. All three desolvated compounds present thermal-\nand light-induced SCO transitions with different degrees of cooperativity and\neffectiveness. Furthermore, 1 and 2 are demonstrated to be sublimable under HV\nconditions affording homogeneous thin films 200 nm thick (TF1 and TF2) that\nretain the chemical integrity of the original molecules regardless the\ndeposition surface. The SCO behaviour of the films is characterized by XAS\ntechnique revealing the partial retainment of both thermal- and light-induced\nspin transitions, yet losing the cooperativity. Finally, SCO/2D horizontal\nhybrid devices based on CVD-graphene are produced using these films. Being the\nfirst ones of this type utilizing molecules of {Fe[H2B(pz)2]2(L)} family, with\nL = tzpy and btz, the devices have allowed the successful detection of the\nthermal SCO transition through the electric properties of the CVD-graphene.",
        "positive": "Bottom-up fabrication of atomically precise graphene nanoribbons: Graphene nanoribbons (GNRs) make up an extremely interesting class of\nmaterials. On the one hand GNRs share many of the superlative properties of\ngraphene, while on the other hand they display an exceptional degree of\ntunability of their optoelectronic properties. The presence or absence of\ncorrelated low-dimensional magnetism, or of a widely tunable band gap, is\ndetermined by the boundary conditions imposed by the width, crystallographic\nsymmetry and edge structure of the nanoribbons. In combination with additional\ncontrollable parame-ters like the presence of heteroatoms, tailored strain, or\nthe formation of hetero-structures, the possibilities to shape the electronic\nproperties of GNRs according to our needs are fantastic. However, to really\nbenefit from that tunability and harness the opportunities offered by GNRs,\natomic precision is strictly required in their synthesis. This can be achieved\nthrough an on-surface synthesis approach, in which one lets appropriately\ndesigned precursor molecules to react in a selective way that ends up forming\nGNRs. In this chapter we review the structure-property relations inherent to\nGNRs, the synthesis approach and the ways in which the var-ied properties of\nthe resulting ribbons have been probed, finalizing with selected examples of\ndemonstrated GNR applications."
    },
    {
        "anchor": "Improved uncertainty quantification for Gaussian process regression\n  based interatomic potentials: The error estimation capability of machine learning interatomic potentials\n(MLIPs) based on probabilistic learning methods such as Gaussian process\nregression (GPR) is currently under-exploited, because of the tendancy of the\npredicted errors to overestimate the true error. We present approaches based on\nmaximising either the marginal likelihood or an alternative likelihood\nconstructed using leave-one-out cross validation to provide improved error\nestimates for interatomic potentials based on GPR. We benchmarked these\napproaches on models representing the Ar trimer, showing significant\nimprovements in the robustness of the predicted error estimates.",
        "positive": "Polarization multistates in antiferroelectric van der Waals materials: The bistability of charge polarization in ferroelectric materials has long\nbeen the basis of ferroelectric devices. However, the ferroelectricity tends to\nbe vanishing as the thickness of materials is reduced to a few nanometers or\nthinner due to the depolarization field. Instead, they show a paraelectric or\nan antiferroelectric ordering in the ultra-thin limit, which is unfavorable for\ntheir applications in devices. Here we uncover polarization multistates in thin\nfilms of van der Waals materials, in which the individual monolayers have an\nantiferroelectric ordering with out-of-plane polarizations. This property\nresults from a unique combination of the polarization and layer degrees of\nfreedom. Using first-principles calculations, we demonstrate that bilayers and\ntrilayers of the CuInP$_2$S$_6$ family possess quintuple and septuple\npolarization states., respectively. Our climbing image nudged elastic band\ncalculations for the bilayers and trilayers of CuInP$_2$S$_6$ and\nCuCrP$_2$S$_6$ further show that the states can be transformed into each other\nunder appropriate external electric fields, for which a unique layer-selective\nhalf-layer-by-half-layer flipping mechanism governs the transformings. Our\nstudy opens up a door to design unusual polarization states using intrinsic\ndegrees of freedom of layered antiferroelectrics for the next-generation\nferroelectric devices that go beyond the bistability paradigm."
    },
    {
        "anchor": "Polyurea-Graphene Nanocomposites -- the Influence of Hard-Segment\n  Content and Nanoparticle Loading on Mechanical Properties: Polyurethane and polyurea-based adhesives are widely used in various\napplications, from automotive to electronics to medical. The adhesive\nperformance depends strongly on its composition, and developing the\nformulation-structure-property relationship is crucial to making better\nproducts. Here, we investigate the dependence of the linear viscoelastic\nproperties of polyurea nanocomposites, with IPDI-based polyurea (PUa) matrix\nand exfoliated graphene nanoplatelet (xGnP) fillers, on the hard segment weight\nfraction (HSWF) and the xGnP loading. We characterize the material using\nscanning electron microscopy (SEM) and dynamical mechanical analysis (DMA). It\nis found that changing HSWF leads to a significant variation in the stiffness\nof the material, from about 10 MPa for the 20% HSWF to about 100 MPa for the\n30% HSWF to about 250 MPa for the 40% HSWF polymer (as measured by the tensile\nstorage modulus at room temperature). The effect of the xGNP loading is\nsignificantly more limited and is generally within experimental error, except\nfor the 20% HSWF material where the xGNP addition leads to about 80% increase\nin stiffness. To correctly interpret the DMA results, we developed a new\nphysics-based rheological model for the description of the storage and loss\nmoduli. The model is based on the fractional calculus approach and successfully\ndescribes the material rheology in a broad range of temperatures (-70{\\deg}C to\n+70{\\deg}C) and frequencies (0.1 to 100 s-1), using only six physically\nmeaningful fitting parameters for each material. The results provide guidance\nfor the development of nanocomposite PUa-based materials.",
        "positive": "Imaging the topological current carrying state and the surface to bulk\n  transformation, in Bi2Se3 single crystal and thin film: Magneto-optics based current imaging technique compares the nature of\ntopological current distribution in a single crystal and thin film of\ntopological insulator material, Bi2Se3. The single crystal, at low\ntemperatures, has uniform topological surface current sheets which are about\n3.6 nm thick. With increasing temperature, the current partially diverts into\nthe crystal bulk and concomitantly, the sheet break up into a patchy network of\nhigh and low current density regions. The temperature dependence of the high\ncurrent density areas shows that the surface to bulk transformation in the\ncrystal has features of classical phase transition phenomena. The surface area\nfraction with topological high current density behaves like an order parameter.\nThis phase transition is driven by disorder. In Bi2Se3 thin film we show the\npresence of quasi one-dimensional topological edge currents which are\nsuppressed with a weak applied magnetic field. The edge current transforms into\na uniform bulk current in the film."
    },
    {
        "anchor": "Atomic-scale effect of 2D \u03c0-conjugated metal-organic frameworks as\n  electrocatalysts for CO2 reduction reaction towards highly selective products: Electrocatalytic CO2 reduction technology is key to mitigating greenhouse gas\nemissions and the energy crisis. However, controlling the selectivity of CO2RR\nproducts at low overpotential remains a challenge. In this paper, we predicted\nfive high-performance CO2RR electrocatalysts with different product-specific\nselectivities at the theoretical level based on the advantages of the\ncompositional structure and the tunable pore size of 2D {\\pi}-conjugated MOFs.\nIn addition, through the reaction mechanism and electronic structure analysis,\nwe found that the synergistic interaction between metal atoms and organic\nlinkers of 2D MOFs can effectively regulate the electronic structure of the\nactive center. Their pore size as well as the diversity of carbon materials can\nregulate the spin magnetic moments of the metal atoms, thus affecting the\nimprovement of their catalytic performance. Meanwhile, the oxygen or carbon\naffinity of the catalyst surface determines the differences in the formation of\nkey intermediates, which ultimately determines the reaction path and product\nselectivity. These insights we present will be useful for the development and\ndesign of highly active CO2RR electrocatalysts.",
        "positive": "Band gap reduction in highly-strained silicon beams predicted by\n  first-principles theory and validated using photoluminescence spectroscopy: A theoretical study of the band gap reduction under tensile stress is\nperformed and validated through experimental measurements. First-principles\ncalculations based on density functional theory (DFT) are performed for\nuniaxial stress applied in the [001], [110] and [111] directions. The\ncalculated band gap reductions are equal to 126, 240 and 100 meV at 2$\\%$\nstrain, respectively. Photoluminescence spectroscopy experiments are performed\nby deformation applied in the [110] direction. Microfabricated specimens have\nbeen deformed using an on-chip tensile technique up to ~1$\\%$ as confirmed by\nback-scattering Raman spectroscopy. A fitting correction based on the band gap\nfluctuation model has been used to eliminate the specimen interference signal\nand retrieve reliable values. Very good agreement is observed between\nfirst-principles theory and experimental results with a band gap reduction of,\nrespectively, 93 and 91 meV when the silicon beam is deformed by 0.95$\\%$ along\nthe [110] direction."
    },
    {
        "anchor": "Phase Transitions in Germanium Telluride Nanoparticle Phase-Change\n  Materials Studied by Time-Resolved X-Ray Diffraction: Germanium telluride (GeTe), a phase-change material, is known to exhibit four\ndifferent structural phases: three at room temperature (one amorphous and two\ncrystalline, $\\alpha$ and $\\gamma$) and one at high temperature (crystalline\n$\\beta$). Because transitions between the amorphous and crystalline phases lead\nto significant changes in material properties (e.g., refractive index and\nresistivity), GeTe has been investigated as a phase-change material for\nphotonics, thermoelectrics, ferroelectrics, and spintronics. Consequently, the\ntemperature-dependent phase transitions in GeTe have been studied for bulk and\nthin-film GeTe, both fabricated by sputtering. Colloidal synthesis of\nnanoparticles offers a more flexible fabrication approach for amorphous and\ncrystalline GeTe. These nanoparticles are known to exhibit size-dependent\nproperties, such as an increased crystallization temperature for the\namorphous-to-$\\alpha$ transition in sub-10\\,nm GeTe particles. The\n$\\alpha$-to-$\\beta$ phase transition is also expected to vary with size, but\nthis effect has not yet been investigated for GeTe. Here, we report\ntime-resolved X-ray diffraction of GeTe nanoparticles with different diameters\nand from different synthetic protocols. We observe a non-volatile\namorphous-to-$\\alpha$ transition between 210$^{\\circ}$C and 240$^{\\circ}$C and\na volatile $\\alpha$-to-$\\beta$ transition between 370$^{\\circ}$C and\n420$^{\\circ}$C. The latter transition was reversible and repeatable. While the\ntransition temperatures are shifted relative to the values known for bulk GeTe,\nthe nanoparticle-based samples still exhibit the same structural phases\nreported for sputtered GeTe. Thus, colloidal GeTe maintains the same general\nphase behavior as bulk GeTe while allowing for more flexible and accessible\nfabrication. Therefore, nanoparticle-based GeTe films show great potential for\napplications, such as in active photonics.",
        "positive": "Giant Enhancement of the Electromechanical Coupling in Soft\n  Heterogeneous Dielectrics: Electroactive soft elastomers require huge electric field for a meaningful\nactuation. We demonstrate that this can be dramatically reduced and giant\ndeformations can be produced by application of suitably chosen heterogeneous\nactuators. The mechanism by which the enhancement is achieved is described and\nillustrated with the aid of both idealized and periodic models."
    },
    {
        "anchor": "Nature of ferroelectric transitions in spin ice Ho2Ti2O7 and Dy2Ti2O7: To investigate the possible origin and mechanism of ferroelectricity in\npolycrystalline spin ices Ho2Ti2O7 and Dy2Ti2O7 a detailed dielectric study has\nbeen performed. Experimental finding suggests that both materials have two\nprominent diffuse ferroelectric phase transitions around 90K and 36K. These\ntransitions are distinctly generated by the lattice distortions at the oxygen\nsites as confirmed by triggered distortions and order of activation energy. Due\nto the incompatibility of the gyrotropic order with any phonon mode at the\nBrillouin zone center, observed diffuse ferroelectric phase transitions can\nhave only an electronic origin. Through magnetic susceptibility and previously\nreported spin relaxation behavior it has been concluded that single ion\nanisotropy has thermal variation, due to which orientation of rare earth\nmagnetic moment from isotropic non-Ising to Ising spin along local <111>axis\ntakes place. This spin orientation distinctly distorting the both oxygen sites\nof the structure reflects in the form of diffuse ferroelectric phase\ntransitions.",
        "positive": "Pb(Mg1/3Nb2/3)O3 (PMN) Relaxor: Dipole Glass or Nano-Domain\n  Ferroelectric ?: Combining our comprehensive investigations of polarization evolution,\nsoft-mode by Raman scattering and microstructure by TEM, and the results\nreported in the literatures, we show that prototypical relaxor Pb(Mg1/3Nb2/3)O3\n(PMN) is essentially ferroelectric for T<Tc~225 K. Its anomalous dielectric\nbehavior over a broad temperature range results from the reorientation of\ndomains in the crystal. A physic picture of the structure evolution in relaxor\nis also revealed. It is found that nanometric ferroelectric domains (gennerally\ncalled as polar nano-region (PNR)) interact cooperatively to form micrometric\ndomain. Such multiscale inhomogeneities of domain structure in addition to the\nwell-known inhomogeneities of chemical composition and local symmetry are\nconsidered to play a crucial role in producing the enigmatic phenomena in\nrelaxor system."
    },
    {
        "anchor": "Fermi Level Dependent Spin Pumping from a Magnetic Insulator into a\n  Topological Insulator: Topological spintronics aims to exploit the spin-momentum locking in the\nhelical surface states of topological insulators for spin-orbit torque devices.\nWe address a fundamental question that still remains unresolved in this\ncontext: does the topological surface state alone produce the largest values of\nspin-charge conversion efficiency or can the strongly spin-orbit coupled bulk\nstates also contribute significantly? By studying the Fermi level dependence of\nspin pumping in topological insulator/ferrimagnetic insulator bilayers, we show\nthat the spin Hall conductivity is constant when the Fermi level is tuned\nacross the bulk band gap, consistent with a full bulk band calculation. The\nresults suggest a new perspective, wherein \"bulk-surface correspondence\" allows\nspin-charge conversion to be simultaneously viewed either as coming from the\nfull bulk band, or from spin-momentum locking of the surface state.",
        "positive": "Spectacular decrease of the melting magnetic field in the charge-ordered\n  state of tensile Pr0.5Ca0.5MnO3 films: An insulator to metal transition below 240K is induced by applying a 7T\nmagnetic field in Pr0.5Ca0.5MnO3 thin films grown by the Pulsed Laser\nDeposition technique on (100) SrTiO3 substrates. This value of the melting\nmagnetic field, much lower that the one required in bulk (20T), is assumed to\nbe an effect of the tensile stress. These results confirm the importance of the\nbandwidth in the control of the physical properties of this compound and open\nthe route to get colossal magnetoresistive properties by using strain effects."
    },
    {
        "anchor": "Complex Magnetic Order in a Decorated Spin Chain System\n  Rb$_2$Mn$_3$(MoO$_4$)$_3$(OH)$_2$: Macroscopic magnetic properties and microscopic magnetic structure of\nRb$_2$Mn$_3$(MoO$_4$)$_3$(OH)$_2$ (space group $Pnma$) are investigated by\nmagnetization, heat capacity and single-crystal neutron diffraction\nmeasurements. The compound's crystal structure contains bond-alternating\n[Mn$_3$O$_{11}$]$^{\\infty}$ chains along the $b$-axis, formed by isosceles\ntriangles of Mn ions occupying two crystallographically nonequivalent sites\n(Mn1 site on the base and Mn2 site on the vertex). These chains are only weakly\nlinked to each other by nonmagnetic oxyanions. Both SQUID magnetometry and\nneutron diffraction experiments show two successive magnetic transitions as a\nfunction of temperature. On cooling, it transitions from a paramagnetic phase\ninto an incommensurate phase below 4.5~K with a magnetic wavevector near ${\\bf\nk}_{1} = (0,~0.46,~0)$. An additional commensurate antiferromagnetically\nordered component arises with ${\\bf k}_{2} = (0,~0,~0)$, forming a complex\nmagnetic structure below 3.5~K with two different propagation vectors of\ndifferent stars. On further cooling, the incommensurate wavevector undergoes a\nlock-in transition below 2.3~K. The experimental results suggest that the\nmagnetic superspace group is $Pnma.1'(0b0)s0ss$ for the single-${\\bf k}$\nincommensurate phase and is $Pn'ma(0b0)00s$ for the 2-${\\bf k}$ magnetic phase.\nWe propose a simplified magnetic structure model taking into account the major\nordered contributions, where the commensurate ${\\bf k}_{2}$ defines the\nordering of the $c$-axis component of Mn1 magnetic moment, while the\nincommensurate ${\\bf k}_{1}$ describes the ordering of the $ab$-plane\ncomponents of both Mn1 and Mn2 moments into elliptical cycloids",
        "positive": "Spatially resolved fluorescence of caesium lead halide perovskite\n  supercrystals reveals quasi-atomic behavior of nanocrystals: We correlate spatially resolved fluorescence (-lifetime) measurements with\nX-ray nanodiffraction to reveal surface defects in supercrystals of\nself-assembled caesium lead halide perovskite nanocrystals and study their\neffect on the fluorescence properties. Upon comparison with density functional\nmodelling, we show that a loss in structural coherence, an increasing atomic\nmisalignment between adjacent nanocrystals, and growing compressive strain near\nthe surface of the supercrystal are responsible for the observed fluorescence\nblueshift and decreased fluorescence lifetimes. Such surface defect-related\noptical properties extend the frequently assumed analogy between atoms and\nnanocrystals as so-called quasi-atoms. Our results emphasize the importance of\nminimizing strain during the self-assembly of perovskite nanocrystals into\nsupercrystals for lighting application such as superfluorescent emitters."
    },
    {
        "anchor": "Multi-plane denoising diffusion-based dimensionality expansion for\n  2D-to-3D reconstruction of microstructures with harmonized sampling: Acquiring reliable microstructure datasets is a pivotal step toward the\nsystematic design of materials with the aid of integrated computational\nmaterials engineering (ICME) approaches. However, obtaining three-dimensional\n(3D) microstructure datasets is often challenging due to high experimental\ncosts or technical limitations, while acquiring two-dimensional (2D)\nmicrographs is comparatively easier. To deal with this issue, this study\nproposes a novel framework for 2D-to-3D reconstruction of microstructures\ncalled Micro3Diff using diffusion-based generative models (DGMs). Specifically,\nthis approach solely requires pre-trained DGMs for the generation of 2D\nsamples, and dimensionality expansion (2D-to-3D) takes place only during the\ngeneration process (i.e., reverse diffusion process). The proposed framework\nincorporates a new concept referred to as multi-plane denoising diffusion,\nwhich transforms noisy samples (i.e., latent variables) from different planes\ninto the data structure while maintaining spatial connectivity in 3D space.\nFurthermore, a harmonized sampling process is developed to address possible\ndeviations from the reverse Markov chain of DGMs during the dimensionality\nexpansion. Combined, we demonstrate the feasibility of Micro3Diff in\nreconstructing 3D samples with connected slices that maintain morphologically\nequivalence to the original 2D images. To validate the performance of\nMicro3Diff, various types of microstructures (synthetic and experimentally\nobserved) are reconstructed, and the quality of the generated samples is\nassessed both qualitatively and quantitatively. The successful reconstruction\noutcomes inspire the potential utilization of Micro3Diff in upcoming ICME\napplications while achieving a breakthrough in comprehending and manipulating\nthe latent space of DGMs.",
        "positive": "Extended Dynamical Equations of the Period Vectors of Crystals under\n  Constant External Stress to Many-body Interactions: Since crystals are made of periodic structures in space, predicting their\nthree period vectors starting from any values based on the inside interactions\nis a basic theoretical physics problem. For the general situation where\ncrystals are under constant external stress, we derived dynamical equations of\nthe period vectors in the framework of Newtonian dynamics, for pair potentials\nrecently (doi:/10.1139/cjp-2014-0518). The derived dynamical equations show\nthat the period vectors are driven by the imbalance between the internal and\nexternal stresses. This presents a physical process where when the external\nstress changes, the crystal structure changes accordingly, since the original\ninternal stress can not balance the external stress. The internal stress has\nboth a full kinetic energy term and a full interaction term. It is extended to\nmany-body interactions in this paper. As a result, all conclusions in the\npair-potential case also apply for many-body potentials."
    },
    {
        "anchor": "Comment on \"Ferroelectrically Induced Weak Ferromagnetism by Design\", C.\n  Fennie, PRL 100, 167203 (2008): The question of how ferroelectric polarization is coupled to magnetism in\nmagnetoelectric multiferroics, in which both types of order are simultaneously\npresent, is of considerable scientific and practical interest. A recent Letter\n\\cite{fennie} presents an analysis of the important ``ABO$_3$'' class of\nperovskite multiferroics. This Letter argues that antiferromagnetic\nmultiferroics with magnetic ions on the B site, such as the well-studied\nroom-temperature multiferroic bismuth ferrite (A=Bi, B=Fe), cannot show linear\nmagnetoelectric coupling of the form ${\\bf P} \\cdot ({\\bf L} \\times {\\bf M})$.\nHere ${\\bf P}$ is polarization and ${\\bf L}$ and ${\\bf M}$ are\nantiferromagnetic and ferromagnetic moments. The conclusion of Ref.\n\\onlinecite{fennie} is that only materials with magnetic A-site have this\ncoupling. This Comment presents a compact analysis of magnetoelectric coupling\nin the ABO$_3$ multiferroics. We show that the argument of Ref.\n\\onlinecite{fennie} does forbid $E_{PLM}$ if the final low-symmetry phase\ncontains only one distortion that, like ${\\bf P}$, breaks all inversion\nsymmetries. In reality, there are multiple distortions in this symmetry class,\nand cross-terms generate $E_{PLM}$. Our analysis gives simple conclusions about\nexistence and optimization of magnetoelectric coupling in ABO$_3$ materials.",
        "positive": "Sub-millimeter propagation of antiferromagnetic magnons via\n  magnon-photon coupling: For the realization of magnon-based current-free technologies, referred to as\nmagnonics, all-optical control of magnons is an important technique for\nfundamental research and application. Magnon-polariton is a coupled state of\nmagnon and photon in a magnetic medium, which is expected to exhibit a\nmagnon-like controllability and a photon-like high-speed propagation. Recent\nstudies have observed magnon-polaritons as modulation of the incident terahertz\nwave; however, the influence of magnon-photon coupling on the magnon\npropagation property has not been explored. This study aimed to observe the\nspatiotemporal dynamics of coherent magnon-polariton through time-resolved\nimaging measurements. $\\mathrm{BiFeO_3}$ was chosen as the sample, because it\nis expected to exhibit strong coupling between the magnon and photon. The\nobserved dynamics suggested that antiferromagnetic magnons can propagate over\nlong distances up to hundreds of micrometers through strong coupling with the\nphotons. The results shed light on the understanding of the optical control of\nthe magnonic systems thereby paving the way for terahertz opto-magnonics."
    },
    {
        "anchor": "Formation and morphology of closed and porous films grown from grains\n  seeded on substrates: Two-dimensional simulations: Two-dimensional simulations are used to explore topological transitions that\noccur during the formation of films grown from grains that are seeded on\nsubstrates. This is done for a relatively large range of the initial value\n$\\Phi_s$ of the grain surface fraction $\\Phi$. The morphology of porous films\nis captured at the transition when grains connect to form a one-component\nnetwork using newly developed raster-free algorithms that combine computational\ngeometry and network theory. Further insight on the morphology of porous films\nand their suspended counterparts is obtained by studying the pore surface\nfraction $\\Phi_p$, the pore over grain ratio, the pore area distribution, and\nthe contribution of pores of certain chosen areas to $\\Phi_p$. Pinhole survival\nis evaluated at the transition when film closure occurs using survival function\nestimates. The morphology of closed films ($\\Phi = 1$) is also characterized\nand is quantified by measuring grain areas and perimeters. The majority of\ninvestigated quantities are found to depend sensitively on $\\Phi_s$ and the\nlong-time persistence of pinholes exhibits critical behavior as a function of\n$\\Phi_s$. In addition to providing guidelines for designing effective processes\nfor manufacturing thin films and suspended porous films with tailored\nproperties, this work may advance the understanding of continuum percolation\ntheory.",
        "positive": "Driving force for martensitic transformation in\n  Ni$_{2}$Mn$_{1+x}$Sn$_{1-x}$: The martensitic transformation in Ni$_{2}$Mn$_{1+x}$Sn$_{1-x}$ alloys has\nbeen investigated within ab-initio density functional theory. The experimental\ntrend of a martensitic transition happening beyond $x$ = 0.36 is captured\nwithin these calculations. The microscopic considerations leading to this are\ntraced to increased Ni-Mn hybridization which results from the Ni atom\nexperiencing a resultant force along a lattice parameter and moving towards the\nMn atoms above a critical concentration. The presence of the lone pair\nelectrons on Sn forces the movement of Ni atoms away from Sn. While band Jahn\nTeller effects have been associated with this transition, we show\nquantitatively that atleast in this class of compounds they have a minor role."
    },
    {
        "anchor": "Ferroelectric control of N\u00e9el vector in L10 type of antiferromagnetic\n  films: How to efficiently manipulate the N\\'eel vector of antiferromagnets (AFM) by\nelectric methods is one of the major focuses in current antiferromagnetic\nspintronics. In this work, we investigated the ferroelectric control of\nmagnetism in AFM L10-MnPt/BaTiO3 bilayers structures by using first-principles\ncalculation. We studied the effect of ferroelectric polarization reversal on\nmagnetic crystalline anisotropy (MCA) of L10-MnPt films with different\ninterface structures. Our results predict a large perpendicular MCA in L10-MnPt\nfilms with Pt-O interface, while an in-plane MCA with Mn-O interface when they\nare interfaced with ferroelectric BaTiO3. In addition, the magnitude of MCA for\nboth interfaces can be modulated efficiently by the polarization reversal of\nBaTiO3. The ferroelectric control of MCA has been analyzed based on second\norder perturbation theory, and it can be mainly attributed to the ferroelectric\npolarization driven redistribution of Pt-5d orbital occupation around Fermi\nenergy. Especially, for Mn-O interface, the N\\'eel vector can be switched\nbetween in-plane [100] and [110] directions, or even from in-plane to\nout-of-plane at certain film thickness by reversing ferroelectric polarization.\nOur results may provide a non-volatile concept for ferroelectric control of\nN\\'eel vector in L10-antiferromagnets, which could stimulate experimental\ninvestigations on magnetoelectric effect of antiferromagnets and promote its\napplications in low-power consumption spintronic memory devices.",
        "positive": "On the Role of Elastic Strain on Electrocatalysis of Oxygen Reduction\n  Reaction on Pt: The effect of elastic strain on catalytic activity of platinum (Pt) towards\noxygen reduction reaction (ORR) is investigated through de-alloyed Pt-Cu thin\nfilms; stress evolution in the de-alloyed layer and the mass of the Cu removed\nare measured in real-time during electrochemical de-alloying of (111)-textured\nthin-film PtCu (1:1, atom %) electrodes. In situ stress measurements are made\nusing the cantilever-deflection method and nano-gravimetric measurements are\nmade using an electrochemical quartz crystal nanobalance. Upon de-alloying via\nsuccessive voltammetric sweeps between -0.05 and 1.15 V vs. standard hydrogen\nelectrode, compressive stress develops in the de-alloyed Pt layer at the\nsurface of thin-film PtCu electrodes. The de-alloyed films also exhibit\nenhanced catalytic activity towards ORR compared to polycrystalline Pt. In situ\nnanogravimetric measurements reveal that the mass of de-alloyed Cu is\napproximately 210 +/- 46 ng/cm2, which corresponds to a de-alloyed layer\nthickness of 1.2 +/- 0.3 monolayers or 0.16 +/- 0.04 nm. The average biaxial\nstress in the de-alloyed layer is estimated to be 4.95 +/- 1.3 GPa, which\ncorresponds to an elastic strain of 1.47 +/- 0.4%. In addition, density\nfunctional theory calculations have been carried out on biaxially strained Pt\n(111) surface to characterize the effect of strain on its ORR activity; the\npredicted shift in the limiting potentials due to elastic strain is found to be\nin good agreement with the experimental shift in the cyclic voltammograms for\nthe dealloyed PtCu thin film electrodes."
    },
    {
        "anchor": "Strain-Driven Zero-Field Near-10 nm Skyrmions in Two-Dimensional van der\n  Waals Heterostructures: Magnetic skyrmions $-$ localized chiral spin structures $-$ show great\npromise for spintronic applications. The recent discovery of two-dimensional\n(2D) magnetic materials opened new opportunities for exploring such topological\nspin structures in atomically thin van der Waals (vdW) materials. Despite\nrecent progress in stabilizing metastable skyrmions in 2D magnets, their\ndiameters are still beyond 100~nm and their lifetime, which is essential for\napplications, has not been explored yet. Here, using first-principles\ncalculations and atomistic spin simulations, we predict that compressive\nmechanical strain leads to stabilizing zero-field skyrmions with diameters\nclose to 10 nm in a Fe$_3$GeTe$_2$/germanene vdW heterostructure. The origin of\nthese unique skyrmions is attributed to the high tunability of\nDzyaloshinskii-Moriya interaction and magnetocrystalline anisotropy energy by\nstrain, an effect which is shown to be general for Fe$_3$GeTe$_2$\nheterostructures with buckled substrates. Based on our first-principles\nparameters for the magnetic interactions, we calculate the energy barriers\nprotecting skyrmions against annihilation and their lifetimes using\ntransition-state theory. We show that nanoscale skyrmions in strained\nFe$_3$GeTe$_2$/germanene can be stable for hours at temperatures up to 20 K.",
        "positive": "Atomistic Coupling between Magnetization and Lattice Dynamics from First\n  Principles: We formulate a new scheme to study the combined magnetization and lattice\ndynamics in magnets, so-called magnetoelastics. The coupling between\nmagnetization and lattice are considered through an expansion of\nelectron-phonon coupling, while the magnetization is coupled to electrons\nthrough sd-like interaction. We show the that the time-scale of the\nmagnetization dynamics due to coupling between magnetic degrees of freedom and\nelectronic degrees of freedom can be transferred to lattice degrees of freedom\nand therefore can give rise to lattice dynamics on the same time-scale. This\nopens a new route to understand and treat ultrafast lattice dynamics induced by\nmagnetization dynamics. We also show that all the parameters necessary to\nsimulate this coupled lattice and magnetization dynamics can be obtained from\nfirst-principles."
    },
    {
        "anchor": "Topological Bonding and Electronic properties of Cd$_{43}$Te$_{28}$\n  semiconductor material with microporous structure: CdTe is II-VI semiconductor material with excellent characteristics and has\ndemonstrated promising potential for application in the photovoltaic field. The\nelectronic properties of Cd43Te28 with microporous structures have been\ninvestigated based on density functional theory. The newly established\nbinding-energy and bond-charge model have been used to convert the value of\nHamiltonian into bonding values. We provide a method for describing topological\nchemical bonds by atomic coordinates and wave phases. We also discuss the\ndynamic process of the wave function with time and the magic cube matrix. This\nstudy provides an innovative method and technology for the accurate analysis of\nthe topological bonding and electronic properties of microporous semiconductor\nmaterials.",
        "positive": "Shortcomings of using the SCAN functional for deep defects and small\n  polarons in semiconductors: We find the recently developed strongly constrained and appropriately\nnormalized (SCAN) functional, now widely used in calculations of many\nmaterials, is not able to reliably describe the properties of deep defects and\nsmall polarons in several semiconductors and insulators. These shortcomings are\ndue to a failure to identify the large structural distortions and charge\nlocalization that accompanies the presence of defects and the formation of\nsmall polarons."
    },
    {
        "anchor": "Interaction effect detected by compared of the irreversible and remanent\n  initial magnetization curves in Ni-Cu-Zn ferrites: A new technique for estimation of magnetic interaction effects of initial\nmagnetization curves has been proposed. It deals with remanence, and initial\nirreversible magnetization, curves. The method is applied for single-phase\npolycrystalline Ni0.85-xCu0.15ZnxFe2O4, (x = 0, 0.2, 0.4 and 0.6), which were\nsynthesized by a standard ceramic technology. A study of the initial reversible\nand irreversible magnetization processes in ferrite materials was carried out.\nThe field dependence of the irreversible, and reversible, magnetizations was\ndetermined by magnetic losses of minor hysteresis loops obtained from different\npoints of an initial magnetization curve. The influence of Zn-substitutions in\nNi-Cu ferrites over irreversible magnetization processes and interactions in\nmagnetic systems has been analyzed.",
        "positive": "ZnO:Co Diluted Magnetic Semiconductor or Hybrid Nanostructure for\n  Spintronics?: We have studied the influence of intrinsic and extrinsic defects in the\nmagnetic and electrical transport properties of Co-doped ZnO thin films. X ray\nabsorption measurements show that Co substitute Zn in the ZnO structure and it\nis in the 2+ oxidation state. Magnetization (M) measurements show that doped\nsamples are mainly paramagnetic. From M vs. H loops measured at 5 K we found\nthat the values of the orbital L and spin S numbers are between 1 and 1.3 for L\nand S = 3/2, in agreement with the representative values for isolated Co 2+.\nThe obtained negative values of the Curie-Weiss temperatures indicate the\nexistence of antiferromagnetic interactions between transition metal atoms."
    },
    {
        "anchor": "Optical beam-induced scattering mode of mid-IR laser microscopy: a\n  method for defect investigation in near-surface and near-interface regions of\n  bulk semiconductors: This paper presents a new technique of optical beam-induced scattering of\nmid-IR-laser radiation, which is a special mode of the recently developed\nscanning mid-IR-laser microscopy. The technique in its present form is designed\nfor investigation of large-scale recombination-active defects in near-surface\nand near-interface regions of semiconductor wafers. However, it can be easily\nmodified for the defect investigations in the crystal bulk. Being in many\nrespects analogous to EBIC, the present technique has some indisputable\nadvantages, which enable its application for both non-destructive laboratory\ninvestigations and quality monitoring in the industry.",
        "positive": "The organic functional group effect on the electronic structure of\n  graphene nano-ribbon: A first-principles study: We report a first-principles study of the electronic structure of\nfunctionalized graphene nano-ribbon (aGNRs-f) by organic functional group\n(CH2C6H5) and find that CH2C6H5 functionalized group does not produce any\nelectronic states in the gap and the band gap is direct. By changing both the\ndensity of the organic functional group and the width of the aGNRs-f, a band\ngap tuning exhibits a fine three family behavior through the side effect.\nMeanwhile, the carriers at conduction band minimum and valence band maximum are\nlocated in both CH2C6H5 and aGNR regions when the density of the CH2C6H5 is\nbig; while they distribute dominantly in aGNR conversely. The band gap\nmodulation effects make the aGNRs-f good candidates with high quantum\nefficiency and much more wavelength choices range from 750 to 93924 nm both for\nlasers, light emitting diodes and photo detectors due to the direct band gap\nand small carrier effective masses."
    },
    {
        "anchor": "Ferroelectricity in AlScN: Switching, Imprint and sub-150 nm Films: The discovery of ferroelectricity in AlScN allowed the first clear\nobservation of the effect in the wurtzite crystal structure, resulting in a\nmaterial with a previously unprecedented combination of very large coercive\nfields (2-5 MV/cm) and remnant polarizations (70-110 ${\\mu}$C/cm$^2$). We\nobtained initial insight into the switching dynamics of AlScN, which suggests a\ndomain wall motion limited process progressing from the electrode interfaces.\nFurther, imprint was generally observed in AlScN films and can tentatively be\ntraced to the alignment of charged defects with the internal and external\npolarization and field, respectively. Potentially crucial from the application\npoint of view, ferroelectricity could be observed in films with thicknesses\nbelow 30 nm - as the coercive fields of AlScN were found to be largely\nindependent of thickness between 600 nm and 27 nm.",
        "positive": "Synthesis and Characterization of Photoreactive TiO2/Carbon Nanosheet\n  Composites: We report the atomic layer deposition of titanium dioxide on carbon nanosheet\ntemplates and investigate the effects of post-deposition annealing in a helium\nenvironment using different characterization techniques. The crystallization of\nthe titanium dioxide coating upon annealing is observed using in-situ X-ray\ndiffraction. The (micro)-structural characterization of the films is carried\nout by scanning electron microscopy and advanced transmission electron\nmicroscopy techniques. Our study shows that the annealing of the atomic layer\ndeposition processed and carbon nanosheets templated titanium dioxide layers in\nhelium environment results in the formation of a porous, nanocrystalline and\nphotocatalytically active titanium dioxide-carbon nanosheet composite film.\nSuch composites are suitable for photocatalysis and dye-sensitized solar cells\napplications."
    },
    {
        "anchor": "A comparison of in- and ex situ generated shear bands in metallic glass\n  by transmission electron microscopy: Shear bands originating from in situ tensile tests of\nAl$_{88}$Y$_{7}$Fe$_{5}$ melt-spun ribbons conducted in a transmission electron\nmicroscope are compared with ones which had formed ex situ during cold rolling.\nDuring in situ straining, the observations of a spearhead-like shear front, a\nmeniscus-like foil thickness reduction and no apparent shear steps to\naccommodate strain suggest shear band initiation by a rejuvenating shear front\nfollowed by shearing along the already softened paths. This leads to necking\nand subsequent failure under the reduced constraint of a 2D geometry in the\nthin foil and thus explains the observed lack of ductility under tension. In\ncontrast, shear bands formed during cold rolling display distinct alternating\ndensity changes and shear off-sets. An explanation for this difference may be\nthat in situ shear bands rip before such features could develop. Moreover, both\nin and ex situ experiments suggest that initiation, propagation and arrest of\nshear bands occur during different stages.",
        "positive": "Surface organization of homoepitaxial InP films grown by metalorganic\n  vapor-phase epitaxy: We present a systematic study of the morphology of homoepitaxial InP films\ngrown by metalorganic vapor-phase epitaxy which are imaged with ex situ atomic\nforce microscopy. These films show a dramatic range of different surface\nmorphologies as a function of the growth conditions and substrate (growth\ntemperature, V/III ratio, and miscut angle < 0.6deg and orientation toward A or\nB sites), ranging from stable step flow to previously unreported strong step\nbunching, over 10 nm in height. These observations suggest a window of growth\nparameters for optimal quality epitaxial layers. We also present a theoretical\nmodel for these growth modes that takes account of deposition, diffusion, and\ndissociation of molecular precursors, and the diffusion and step incorporation\nof atoms released by the precursors. The experimental conditions for step flow\nand step bunching are reproduced by this model, with the step bunching\ninstability caused by the difference in molecular dissociation from above and\nbelow step edges, as was discussed previously for GaAs (001)."
    },
    {
        "anchor": "Intrinsic Instability of the Hybrid Halide Perovskite Semiconductor\n  CH3NH3PbI3: The organic-inorganic hybrid perovskite CH3NH3PbI3 has attracted significant\ninterest for its high performance in converting solar light into electrical\npower with an efficiency exceeding 20%. Unfortunately, chemical stability is\none major challenge in the development of the CH3NH3PbI3 solar cells. It was\ncommonly assumed that moisture or oxygen in the environment causes the poor\nstability of hybrid halide perovskites, however, here we show from the\nfirst-principles calculations that the room-temperature tetragonal phase of\nCH3NH3PbI3 is thermodynamically unstable with respect to the phase separation\ninto CH3NH3I + PbI2, i.e., the disproportionation is exothermic, independent of\nthe humidity or oxygen in the atmosphere. When the structure is distorted to\nthe low-temperature orthorhombic phase, the energetic cost of separation\nincreases, but remains small. Contributions from vibrational and\nconfigurational entropy at room temperature have been considered, but the\ninstability of CH3NH3PbI3 is unchanged. When I is replaced by Br or Cl, Pb by\nSn, or the organic cation CH3NH3 by inorganic Cs, the perovskites become more\nstable and do not phase-separate spontaneously. Our study highlights that the\npoor chemical stability is intrinsic to CH3NH3PbI3 and suggests that\nelement-substitution may solve the chemical stability problem in hybrid halide\nperovskite solar cells.",
        "positive": "An iterative method for reference pattern selection in high resolution\n  electron backscatter diffraction (HR-EBSD): For high (angular) resolution electron backscatter diffraction (HR-EBSD), the\nselection of a reference diffraction pattern (EBSP0) significantly affects the\nprecision of the calculated strain and rotation maps. This effect was\ndemonstrated in plastically deformed body-centred cubic and face-centred cubic\nductile metals (ferrite and austenite grains in duplex stainless steel) and\nbrittle single-crystal silicon, which showed that the effect is not only\nlimited to measurement magnitude but also spatial distribution. An empirical\nrelationship was then identified between the cross-correlation parameter and\nangular error, which was used in an iterative algorithm to identify the optimal\nreference pattern that maximises the precision of HR-EBSD."
    },
    {
        "anchor": "Thermal Boundary Characteristics of Homo-/Heterogeneous Interfaces: The interface of two solids in contact introduces a thermal boundary\nresistance (TBR), which is challenging to measure from experiments. Besides, if\nthe interface is reactive, it can form an intermediate recrystallized or\namorphous region, and extra influencing phenomena are introduced. Reactive\nforce field Molecular Dynamics (ReaxFF MD) is used to study these interfacial\nphenomena at the (non-)reactive interface. The non-reactive interfaces are\ncompared using a phenomenological theory (PT), predicting the temperature\ndiscontinuity at the interface. By connecting ReaxFF MD and PT we confirm a\ncontinuous temperature profile for the homogeneous non-reactive interface and a\ntemperature jump in case of the heterogeneous non-reactive interface. ReaxFF MD\nis further used to understand the effect of chemical activity of two solids in\ncontact. The selected Si/SiO$_2$ materials showed that the TBR of the reacted\ninterface is two times larger than the non-reactive, going from $1.65\\times\n10^{-9}$ to $3.38\\times 10^{-9}$ m$^2$K/W. This is linked to the formation of\nan intermediate amorphous layer induced by heating, which remains stable when\nthe system is cooled again. This provides the possibility to design\nmulti-layered structures with a desired TBR.",
        "positive": "Landau level spectroscopy of massive Dirac fermions in\n  single-crystalline ZrTe5 thin flakes: We report infrared magneto-spectroscopy studies on thin crystals of an\nemerging Dirac material ZrTe5 near the intrinsic limit. The observed structure\nof the Landau level transitions and zero-field infrared absorption indicate a\ntwo-dimensional Dirac-like electronic structure, similar to that in graphene\nbut with a small relativistic mass corresponding to a 9.4 meV energy gap.\nMeasurements with circularly polarized light reveal a significant electron-hole\nasymmetry, which leads to splitting of the Landau level transitions at high\nmagnetic fields. Our model, based on the Bernevig-Hughes-Zhang effective\nHamiltonian, quantitatively explains all observed transitions, determining the\nvalues of the Fermi velocity, Dirac mass (or gap), electron-hole asymmetry, and\nelectron and hole g-factors."
    },
    {
        "anchor": "Hydro-dynamics of surface patterning by ion beam irradiation: an\n  interface phenomenon: We show that the ion beam induced incompressible amorphous solid flow in\nterms of advection transport mechanism leads to the erosion and deposition of\natoms at the amorphous/crystalline (a/c) interface resulting in the formation\nof pattern at the a/c interface as well as at the free surface. The ion beam\nimpact generated erosion and mass redistribution at the free surface are found\nto have insignificant effect in patterning of surface. By varying the\nthicknesses of amorphous layer, it has been established that a/c interface\nplays the dominant role in surface patterning. The morphological variation of\nSi surface after 50 keV Ar+ ion bombardment has been investigated by atomic\nforce microscopy (AFM) and cross-sectional transmission electron microscopy\n(X-TEM) as a function of ion fluence. Navier-Stokes flow inside the amorphous\nlayer coupled with the Exner equation successfully explains the growth\nmechanism of surface patterning.",
        "positive": "Interfacial phenomena in nanocapacitors with multifunctional oxides: The analysis of the structure, chemical stability, electronic and\nferroelectric properties of the interfaces between Pt(001) and PbZrTiO$_3$(001)\n(PZT) have been performed with $ab$ $initio$ methods. We show that the chemical\nenvironment plays a critical role in determining the interfacial reconstruction\nand charge redistribution at the metal/oxide interfaces. We demonstrate that\nthe difference in interfacial bonds formed at the Pt/PZT interfaces with\n(TiZr)O$_2$ - and PbO- termination of PZT essentially defines the effectiveness\nof the screening, and ease of polarisation switching in PZT-based capacitors.\nThe imperfect screening in Pt/PZT/Pt capacitors is caused by strong interfacial\nbonds formed at the interface with (TiZr)O$_2$-terminated film, which is\naccompanied by the suppressed polarisation of PZT film. In contrast, the\ncapacitors with PbO-terminated PZT show a negligible depolarising field and\nhigh polarisation, which is the consequence of weak bonds formed at this type\nof interfaces. The latter also causes a higher switching barrier than that in\nthe former system."
    },
    {
        "anchor": "Collective topological spin dynamics in a correlated spin glass: The interplay between spin-orbit interaction (SOI) and magnetic order is\ncurrently one of the most active research fields in condensed matter physics\nand leading the search for materials with novel and tunable magnetic and spin\nproperties. Here we report on a variety of unexpected and unique observations\nin thin multiferroic \\Ge$_{1-x}$Mn$_x$Te films. The ferrimagnetic order in this\nferroelectric semiconductor is found to reverse with current pulses six orders\nof magnitude lower as for typical spin-orbit torque systems. Upon a switching\nevent, the magnetic order spreads coherently and collectively over macroscopic\ndistances through a correlated spin-glass state. Lastly, we present a novel\nmethodology to controllably harness this stochastic magnetization dynamics,\nallowing us to detect spatiotemporal nucleation of topological spin textures we\nterm ``skyrmiverres''.",
        "positive": "Gold Nanoparticles supported on MoS2 Nanoribbons matrix as a\n  biocompatible and water dispersible platform for enhanced photothermal\n  ablation of cancerous cells using harmless near infrared irradiation: With photothermal efficiency higher than traditionally used reduced graphene\noxide, while simultaneously being water dispersible, we propose biocompatible\nMolybdenum Nanoribbons - gold Nanoparticles (MoS2 NR-Au NPs) system for\nsynergistically enhanced photo-thermal ablation of cancerous cells (100%\nfatality) using NIR radiation (808nm), owing to commendable temperature rise\nabove 70oC at a much faster rate."
    },
    {
        "anchor": "Nanoscale imaging of He-ion irradiation effects on amorphous TaO$_x$\n  toward electroforming-free neuromorphic functions: Resistive switching in thin films has been widely studied in a broad range of\nmaterials. Yet the mechanisms behind electroresistive switching have been\npersistently difficult to decipher and control, in part due to their\nnon-equilibrium nature. Here, we demonstrate new experimental approaches that\ncan probe resistive switching phenomena, utilizing amorphous TaO$_x$ as a model\nmaterial system. Specifically, we apply Scanning Microwave Impedance Microscopy\n(sMIM) and cathodoluminescence (CL) microscopy as direct probes of conductance\nand electronic structure, respectively. These methods provide direct evidence\nof the electronic state of TaO$_x$ despite its amorphous nature. For example CL\nidentifies characteristic impurity levels in TaO$_x$, in agreement with first\nprinciples calculations. We applied these methods to investigate He-ion-beam\nirradiation as a path to activate conductivity of materials and enable\nelectroforming-free control over resistive switching. However, we find that\neven though He-ions begin to modify the nature of bonds even at the lowest\ndoses, the films conductive properties exhibit remarkable stability with large\ndisplacement damage and they are driven to metallic states only at the limit of\nstructural decomposition. Finally, we show that electroforming in a nanoscale\njunction can be carried out with a dissipated power of < 20 nW, a much smaller\nvalue compared to earlier studies and one that minimizes irreversible\nstructural modifications of the films. The multimodal approach described here\nprovides a new framework toward the theory/experiment guided design and\noptimization of electroresistive materials.",
        "positive": "Ethanol chemisorption on core-shell Pt-nanoparticles: an ab-initio study: By means of ab-initio calculations, we have investigated the chemisorption\nparoperties of ethanol onto segregating binary nanoalloys. We select\nnanostructures with icosahedral shape of 55 atoms with a Pt outermost layer\nover a M core with M=Ag,Pd,Ni. With respect to nanofilms with equivalent\ncomposition, there is an increse of the ethanol binding energy. This is not\nmerely due to observed shortening of the Pt-O distance but depends on the\nnanoparticle distortion after ethanol adsorption. This geometrical distortion\nwithin the nanoparticle can be interpreted as a radial breathing, which is\nsensitive to the adsortion site, identified by the O-anchor point and the\nrelative positions of the ethyl group. More interestingly, being core-dependent\n-larger in Pd@Pt and smaller in Ni@Pt-, it relates to an effective electron\ntransfer from ethanol and the M-core towards the Pt-shell. On the view of this\nnew analysis, Pd@Pt nanoalloys show the most promissing features for ethanol\noxidation."
    },
    {
        "anchor": "Spin-fluctuation mechanism of anomalous temperature dependence of\n  magnetocrystalline anisotropy in itinerant magnets: The origins of the anomalous temperature dependence of magnetocrystalline\nanisotropy in (Fe$_{1-x}$Co$_{x}$)$_{2}$B alloys are elucidated using\nfirst-principles calculations within the disordered local moment model.\nExcellent agreement with experimental data is obtained. The anomalies are\nassociated with the changes in band occupations due to Stoner-like band shifts\nand with the selective suppression of spin-orbit \"hot spots\" by thermal spin\nfluctuations. Under certain conditions, the anisotropy can increase, rather\nthan decrease, with decreasing magnetization due to these peculiar electronic\nmechanisms, which contrast starkly with those assumed in existing models.",
        "positive": "Non-Markovian coherence dynamics of driven spin boson model: damped\n  quantum beat or large amplitude coherence oscillation: The dynamics of driven spin boson model is studied analytically by means of\nthe perturbation approach based on a unitary transformation. We gave the\nanalytical expression for the population difference and coherence of the two\nlevel system. The results show that in the weak driven case, the population\ndifference present damped coherent oscillation (single or double frequency) and\nthe frequencies depend on the initial state. The coherence exhibit damped\noscillation with Rabi frequency. When driven field is strong enough, the\npopulation difference exhibit undamped large-amplitude coherent oscillation.\nThe results easily return to the two extreme cases without dissipation or\nwithout periodic driven."
    },
    {
        "anchor": "Smooth relativistic Hartree-Fock pseudopotentials for H to Ba and Lu to\n  Hg: We report smooth relativistic Hartree-Fock pseudopotentials (also known as\naveraged relativistic effective potentials or AREPs) and spin-orbit operators\nfor the atoms H to Ba and Lu to Hg. We remove the unphysical extremely\nnon-local behaviour resulting from the exchange interaction in a controlled\nmanner, and represent the resulting pseudopotentials in an analytic form\nsuitable for use within standard quantum chemistry codes. These\npseudopotentials are suitable for use within Hartree-Fock and correlated wave\nfunction methods, including diffusion quantum Monte Carlo calculations.",
        "positive": "Orbital magneto-optical response of periodic insulators from first\n  principles: Magneto-optical response, i.e. optical response in the presence of a magnetic\nfield, is commonly used for characterization of materials and in optical\ncommunications. However, quantum mechanical description of electric and\nmagnetic fields in crystals is not straightforward as the position operator is\nill defined. We present a reformulation of the density matrix perturbation\ntheory for time-dependent electromagnetic fields under periodic boundary\nconditions, which allows us to treat the orbital magneto-optical response of\nsolids at the \\textit{ab initio} level. The efficiency of the computational\nscheme proposed is comparable to standard linear-response calculations of\nabsorption spectra and the results of tests for molecules and solids agree with\nthe available experimental data. A clear signature of the valley Zeeman effect\nis revealed in the continuum magneto-optical spectrum of a single layer of\nhexagonal boron nitride. The present formalism opens the path towards the study\nof magneto-optical effects in strongly driven low-dimensional systems."
    },
    {
        "anchor": "Two-Dimensional Electron Gas with High Mobility Forming at BaO/SrTiO3\n  Interface: Two-dimensional electron gas (2DEG) formed at the interface between two\ninsulating oxides offers an opportunity for fundamental research and device\napplications. Binary alkaline earth metal oxides possess compatible lattice\nconstants with both silicon and perovskite oxides, exhibiting an enormous\npotential to bridging those two materials classes for multifunctionalities.\nHere we report the formation of 2DEG at the interface between the rock-salt BaO\nand SrTiO3. The highest electron mobility reaches 69000 cm^2 V.S^-1 at 2 K,\nleading to the typical Shubniko de Haas (SdH) oscillations under the high\nmagnetic fields. The presence of SdH oscillations at different field-angles\nreveals a quasi-two-dimensional character of the Fermi surface. The\nfirst-principles calculations suggest that the effective charge transfer from\nthe BaO to Ti 3dxy orbital at the interfaces is responsible to the observed\nhigh carrier mobility. Our results demonstrate that the BaO/STO heterointerface\nis a platform for exploring the correlated quantum phases, opening a door to\nthe low-power and mesoscopic electronic devices.",
        "positive": "Magnetic properties of Ruddlesden-Popper phases\n  Sr$_{3-x}$Y$_{x}$(Fe$_{1.25}$Ni$_{0.75}$)O$_{7-\u03b4}$: A combined\n  experimental and theoretical investigation: We present a comprehensive study of the magnetic properties of\nSr$_{3-x}$Y$_{x}$(Fe$_{1.25}$Ni$_{0.75}$)O$_{7-\\delta}$ ($0 \\leq x \\leq 0.75$).\nExperimentally, the magnetic properties are investigated using superconducting\nquantum interference device (SQUID) magnetometry and neutron powder diffraction\n(NPD). This is complemented by the theoretical study based on density\nfunctional theory as well as the Heisenberg exchange parameters. Experimental\nresults show an increase in the N\\'eel temperature ($T_N$) with the increase of\nY concentrations and O occupancy. The NPD data reveals all samples are\nantiferromagnetically ordered at low temperatures, which has been confirmed by\nour theoretical simulations for the selected samples. Our first-principles\ncalculations suggest that the 3D magnetic order is stabilized due to finite\ninter-layer exchange couplings. The latter give rise to a finite inter-layer\nspin correlations which disappear above the $T_N$."
    },
    {
        "anchor": "Antiferromagnetic skyrmion crystal in Janus monolayer CrSi2N2As2: Antiferromagnetic skyrmion crystal (AF-SkX), a regular array of\nantiferromagnetic skyrmions, is a fundamental phenomenon in the field of\ncondensed-matter physics. So far, only very few proposals have been made to\nrealize the AF-SkX, and most based on three-dimensional (3D) materials. Herein,\nusing first-principles calculations and Monte-Carlo simulations, we report the\nidentification of AF-SkX in two-dimensional lattice of Janus monolayer\nCrSi2N2As2. Arising from the broken inversion symmetry and strong spin-orbit\ncoupling, large Dzyaloshinskii-Moriya interaction is obtained in Janus\nmonolayer CrSi2N2As2. This, combined with the geometric frustration of its\ntriangular lattice, gives rise to the skyrmion physics and long-sought AF-SkX\nin the presence of external magnetic field. More intriguingly, this system\npresents two different antiferromagnetic skyrmion phases, and such phenomenon\nis distinct from those reported in 3D systems. Furthermore, by contacting with\nSc2CO2, the creation and annihilation of AF-SkX in Janus monolayer CrSi2N2As2\ncan be achieved through ferroelectricity. These findings greatly enrich the\nresearch on antiferromagnetic skyrmions.",
        "positive": "Improved quasiparticle self-consistent electronic band structure and\n  excitons in $\u03b2$-LiGaO$_2$: The band structure of $\\beta$-LiGaO$_2$ is calculated using the quasiparticle\nself-consistent QS$G\\hat W$ method where the screened Coulomb interaction $\\hat\nW$ is evaluated including electron-hole interaction ladder diagrams and $G$ is\nthe one-electron Green's function. Improved convergence compared to previous\ncalculations leads to a significantly larger band gap of about 7.0 eV. However,\nexciton binding energies are found to be large and lead to an exciton gap of\nabout 6.0 eV if also a zero-point-motion correction of about $-0.4$ eV is\nincluded. These results are in excellent agreement with recent experimental\nresults on the onset of absorption. Besides the excitons observed thus far, the\ncalculations indicate the existence of a Rydberg-like series of exciton excited\nstates, which is however modified from the classical Wannier exciton model by\nthe anisotropies of the material and the more complex mixing of Bloch states in\nthe excitons resulting from the Bethe-Salpeter equation. The exciton fine\nstructure and the exciton wave functions are visualized and analyzed in various\nways."
    },
    {
        "anchor": "Self-current induced spin-orbit torque in FeMn/Pt multilayers: Extensive efforts have been devoted to the study of spin-orbit torque in\nferromagnetic metal/heavy metal bilayers and exploitation of it for\nmagnetization switching using an in-plane current. As the spin-orbit torque is\ninversely proportional to the thickness of the ferromagnetic layer, sizable\neffect has only been realized in bilayers with an ultrathin ferromagnetic\nlayer. Here we demonstrate that, by stacking ultrathin Pt and FeMn alternately,\nboth ferromagnetic properties and current induced spin-orbit torque can be\nachieved in FeMn/Pt multilayers without any constraint on its total thickness.\nThe critical behavior of these multilayers follows closely three-dimensional\nHeisenberg model with a finite Curie temperature distribution. The spin torque\neffective field is about 4 times larger than that of NiFe/Pt bilayer with a\nsame equivalent NiFe thickness. The self-current generated spin torque is able\nto switch the magnetization reversibly without the need for an external field\nor a thick heavy metal layer. The removal of both thickness constraint and\nnecessity of using an adjacent heavy metal layer opens new possibilities for\nexploiting spin-orbit torque for practical applications.",
        "positive": "Reversible modulation and ultrafast dynamics of THz resonances in\n  strongly photoexcited metamaterials: We demonstrate an ultrafast reversible modulation of resonant terahertz (THz)\nresponse in strongly photoexcited metamaterials. The transient\nspectral-temporal response of the dipole transition ~1.6 THz exhibits a\ndistinct non-monotonic variation as a function of pump fluence. The transition\nenergy shift, strength, spectral width and density-dependent ultrafast\nrelaxation manifest a remarkable re-emergence of the resonances after initial\nquenching. Our simulation, incorporating the first-order diffraction from the\nphotoinduced transient grating, reproduces the salient features, providing a\nnew avenue for designing nonlinear and frequency-agile THz modulators."
    },
    {
        "anchor": "Morse potential derived from first principles: We show that a direct connection can be drawn, based on fundamental quantum\nprinciples, between the Morse potential, extensively used as an empirical\ndescription for the atomic interaction in diatomic molecules, and the harmonic\npotential. This is conceptually achieved here through a non-additive\ntranslation operator, whose action leads to a perfect equivalence between the\nquantum harmonic oscillator in deformed space and the quantum Morse oscillator\nin regular space. In this way, our theoretical approach provides a distinctive\nfirst principle rationale for anharmonicity, therefore revealing a possible\nquantum origin for several related properties as, for example, the dissociation\nenergy of diatomic molecules and the deformation of cubic metals.",
        "positive": "Powder diffraction in Bragg-Brentano geometry with straight linear\n  detectors: A common way of speeding up powder diffraction measurements is the use of one\nor two dimensional detectors. This usually goes along with worse resolution and\nasymmetric peak profiles. In this work the influence of a straight linear\ndetector on the resolution function in the Bragg-Brentano focusing geometry is\ndiscussed. Due to the straight nature of most modern detectors geometrical\ndefocusing occurs which heavily influences the line shape of diffraction lines\nat low angles. An easy approach to limit the resolution degrading effects is\npresented. The presented algorithm selects an adaptive range of channels of the\nlinear detector at low angles, resulting in increased resolution. At higher\nangles still the whole linear detector is used and the data collection remains\nfast. Using this algorithm a well-behaved resolution function is obtained in\nthe full angular range, whereas using the full linear detector the resolution\nfunction varies within one pattern which hinders line shape and Rietveld\nanalysis."
    },
    {
        "anchor": "Twisted domain walls and skyrmions in perpendicularly magnetized\n  multilayers: We present an analytical theory to describe three-dimensional magnetic\ntextures in perpendicularly magnetized magnetic multilayers that arise in the\npresence of magnetostatic interactions and the Dzyaloshinskii-Moriya\ninteraction (DMI). We demonstrate that domain walls in multilayers develop a\ncomplex twisted structure, which persists even for films with strong DMI. The\norigin of this twist is surface-volume stray field interactions that manifest\nas a depth-dependent effective field whose form mimics the DMI effective field.\nWe find that the wall twist has a minor impact on the equilibrium skyrmion or\ndomain size, but can significantly affect current-driven dynamics. Our\nconclusions are based on the derived analytical expressions for the\nmagnetostatic energy and confirmed by micromagnetic simulations.",
        "positive": "Three-axis torque investigation of interfacial exchange coupling in a\n  NiFe/CoO bilayer micromagnetic disk: Micrometer diameter bilayers of NiFe (permalloy, Py) and cobalt oxide (CoO)\ndeposited on nanomechanical resonators were used to investigate exchange bias\neffects. The mechanical compliances of two resonator axes were enhanced by\nsevering one torsion arm, resulting in a unique three-axis resonator that\nresponds resonantly to torques generated by a three-axis RF field. Our\ntechnique permits simultaneous measurement of three orthogonal torque\ncomponents. Measurements of the anisotropies associated with interfacial\nexchange coupling effects have been made. At cryogenic temperatures,\nobservations of shifted linear hysteresis loops confirmed the presence of\nexchange bias from the Py/CoO interface. An in-plane rotating DC bias field was\nused to probe in-plane anisotropies through the out-of-plane torque. Training\neffects in the rotational hysteresis data were observed and showed that\nfeatures due to interfacial coupling did not diminish irrespective of\nsubstantial training of the unidirectional anisotropy. The data from the\nrotational hysteresis loops were fit with parameters from a macrospin solution\nto the Landau-Lifshitz-Gilbert equation. Each parameter of the exchange bias\nmodel accounts for specific features of the rotational loop."
    },
    {
        "anchor": "Polaronic hole-trapping in doped $\\rm BaBiO_3$: The present {\\em ab initio} study shows that in BaBiO$_3$, Bi$^{3+}$ sites\ncan trap two holes from the valence band to form Bi$^{5+}$ cations. The\ntrapping is accompanied by large local lattice distortions, therefore the\ncomposite particle consisting of the electronic-hole and the local lattice\nphonon field forms a polaron. Our study clearly shows that even $sp$ elements\ncan trap carriers at lattice sites, if local lattice relaxations are\nsufficiently large to screen the localised hole. The derived model describes\nall relevant experimental results, and settles the issue of why hole doped\nBaBiO$_3$ remains semiconducting upon moderate hole doping.",
        "positive": "Theoretical-Experimental failure analysis of the c-Al0.66Ti0.33N-M2\n  steel system using nanoindentation instrumented and finite element analysis: A theoretical-experimental methodology for failure analysis of the\nc-Al0.66Ti0.33N / Interface / M2 steel coating system is proposed here. This\nc-Al0.66Ti0.33N coating was deposited by the arc-PVD technique. For coating\nmodeling the traction-separation law and the extended finite element\nmethod-XFEM were applied, the cohesive zones model was used for interface\nmodeling and the Ramberg-Osgood law for substrate modeling. Experimental values\nusing the instrumented nanoindentation technique, the scratch test and tensile\nstress test were obtained and introduced into the model. By means of\nnanoindentation the elastic modulus of coating, the fracture energy release\nrate and the nano-hardness. Normal and shear stress values of the interface\nwere obtained with the scratch test, at the adhesive and cohesive critical\nloads. Vickers indentation was used to generate cracking patterns in the\nc-Al0.66Ti0.33N / Interface / M2 steel coating system. Radial and lateral\ncracks were generated and analyzed after transversal FIB cuts of the fracture\nzones. A finite element analysis was carried out to understand the relationship\nbetween the load-displacement curve and mechanical failure of in the system,\nassociating the pop-in with nucleation, crack growth and cracking pattern. This\nworks present a theoretical-experimental methodology for failure analysis of\nhard coatings (monolithic body) allowing to calculate fracture toughness of the\ncoating material and model cracking patterns caused by contact mechanics."
    },
    {
        "anchor": "Color Change Effect in an Organic-Inorganic Hybrid Material Based on a\n  Porphyrin Diacid: Porphyrinic materials show a range of interesting and useful optical and\nelectrical properties. The less well-known sub-class of porphyrin diacids has\nbeen used in this work to construct an ionic hybrid organic-inorganic material\nin combination with a halogenidometalate anion. The resulting compound,\n$[H_6TPyP][BiCl_6]_2$ (1) (TPyP = tetra(4-pyridyl)porphyrin) has been obtained\nvia a facile solution based synthesis in single crystalline form. The material\nexhibits a broad photoluminescence emission band between 650 and 850 nm at room\ntemperature. Single crystals of $[H_6TPyP][BiCl_6]_2$ show a photocurrent in\nthe fA and a much higher dark current in the nA range. They also display an\nunexpected reversible color change upon wetting with different liquids. This\nphenomenon has been investigated with optical spectroscopy, SEM, XPS and NEXAFS\ntechniques, showing that a surface-based structural coloration effect is the\nsource of the color change. This stands in contrast to other materials where\nstructural coloration typically has to be introduced through elaborate,\nmulti-step processes or the use of natural templates. Additionally, it\nunderscores the potential of self-assembly of porphyrinic hybrid compounds in\nthe fabrication of materials with unusual optical properties.",
        "positive": "Hidden Symmetry of Flexoelectric Coupling: Considering the importance of the flexoelectric coupling for the physical\nunderstanding of the gradient-driven couplings in mesoscale and nanoscale\nsolids, one has to determine its full symmetry and numerical values. The\ntotality of available experimental and theoretical information about the\nflexocoupling tensor symmetry (specifically the amount of measurable\nindependent components) and numerical values is contradictory indicating on a\nlimited understanding of the coupling properties. However the discrepancy\nbetween the theory and experiment can be eliminated by consideration all\npossible inner symmetries of the flexocoupling tensor and physical limits on it\ncomponents values. Specifically this study reveals the inner \"hidden\" symmetry\nof the static flexoelectric tensor that allows minimizing the number of its\nindependent components to the numbers observed experimentally. Revealed hidden\nsymmetry leads to nontrivial physical sequences, namely it affects on the upper\nlimits of the static flexocoupling constants. Also we analyze the dynamic\nflexoelectric coupling symmetry and established the upper limits for the\nnumerical values of its components. These results can help to understand and\nquantify the fundamentals of the gradient-type couplings in different solids."
    },
    {
        "anchor": "Plastic strain accommodation and acoustic emission during melting of\n  embedded particles: Melting point phenomena of micron-sized indium particles embedded in an\naluminum matrix were studied by means of acoustic emission. The acoustic energy\nmeasured during melting increased with indium content. Acoustic emission during\nthe melting transformation suggests a dislocation generation mechanism to\naccommodate the 2.5% volume strain required for melting of the embedded\nparticles. A geometrically necessary increase in dislocation density of 4.1 x\n10^13 m^-2 was calculated for the 17 wt% indium composition.",
        "positive": "Negative ionic states of tin in the oxide superconductor Sr$_{3-x}$SnO\n  revealed by M\u00f6ssbauer spectroscopy: We report the temperature variation of the $^{119}$Sn-M\\\"{o}ssbauer spectra\nof the antiperovskite (inverse perovskite) oxide superconductor Sr$_{3-x}$SnO.\nBoth superconductive (Sr-deficient) and non-superconductive (nearly\nstoichiometric) samples exhibit major $\\gamma$-ray absorption with isomer shift\nsimilar to that of Mg$_2$Sn. This fact shows that Sr$_{3-x}$SnO contains the\nmetallic anion Sn$^{4-}$, which is rare especially among oxides. In both\nsamples, we observed another $\\gamma$-ray absorption with a larger isomer\nshift, indicating that there is another ionic state of Sn with a higher\noxidation number. The temperature dependence of the absorption intensities\nreveals that the Sn ions exhibiting larger isomer shifts have a lower energy of\nthe local vibration. The larger isomer shift and lower vibration energy are\nconsistent with the values estimated from the first-principles calculations for\nhypothetical structures with various Sr-deficiency arrangements. Therefore, we\nconclude that the additional $\\gamma$-ray absorptions originate from the Sn\natoms neighboring the Sr deficiency."
    },
    {
        "anchor": "An Experimental Estimation Method of Diffusion Coefficients in Ternary\n  and Multicomponent Systems from a Single Diffusion Couple Profile: Until recently, it was textbook knowledge that the diffusion coefficients\ncould not be estimated in a multi-component system following the widely\npractised diffusion couple method. The recently proposed constrained diffusion\ncouple methods need two intersecting diffusion paths in a multi-component space\nwith very well-controlled compositions of the diffusion couple end members,\nwhich may be tricky depending on the complications of diffusion paths in\ncertain systems. In this study, we have proposed a method for estimating all\ntypes of diffusion coefficients directly at the Kirkendall marker plane from a\nsingle diffusion couple. The estimation method and design strategy for\nproducing diffusion couples are discussed in concentrated ternary Ni-Co-Fe,\nFe-rich quaternary Fe-Ni-Co-Cr and Ni-rich Ni-Co-Fe-Cr-Al quinary alloys. As\ndemonstrated further, one can even estimate the impurity diffusion coefficients\nutilizing the composition profiles at the ends of the diffusion couples, which\nhas been rarely practised in multicomponent systems until now. We have further\ndemonstrated the importance of estimating the tracer and intrinsic diffusion\ncoefficients in a concentrated or multi-principal element alloy in which\ninterdiffusion coefficients can be vague and misleading for understanding the\nelements' diffusional interactions and relative mobilities. We have also shown\nthe importance of considering the vacancy wind effect in concentrated alloys.\nThe method and design strategy of producing diffusion couples demonstrated in\nthis study can be suitable for generating a mobility database in Ni-, Co-based\n(superalloys) and Fe-based (steel) multicomponent systems with relative ease,\nwhich was considered impossible until recently.",
        "positive": "Interfacial stress transfer in monolayer and few-layer MoS2 nanosheets\n  in model nanocomposites: Understanding the stress transfer mechanisms from a polymer matrix to\ntwo-dimensional reinforcements is essential for the preparation of high\nperformance nanocomposites. In this study, the interfacial stress transfer from\na flexible polymer substrate to monolayer and few-layer molybdenum disulfide\nMoS2 under tension has been investigated. Layer-dependent and strain-dependent\nphotoluminescence (PL) spectroscopy were used to examine the stress transfer\nefficiency."
    },
    {
        "anchor": "Infrared-active phonons in one-dimensional materials and their\n  spectroscopic signatures: Dimensionality provides a clear fingerprint on the dispersion of\ninfrared-active, polar-optical phonons. For these phonons, the local dipoles\nparametrized by the Born effective charges drive the LO-TO splitting of bulk\nmaterials; this splitting actually breaks down in two-dimensional materials.\nHere, we extend the existing theory to the one-dimensional (1D) case. Combining\nan analytical model with the implementation of density-functional perturbation\ntheory in 1D boundary conditions, we show that the dielectric splitting in the\ndispersion relations collapses logarithmically at the zone center. The\ndielectric properties and the radius of the 1D materials are linked by the\npresent work to these red shifts, opening novel IR and Raman characterization\navenues.",
        "positive": "Tailoring Magnetic Frustration in Strained Epitaxial FeRh Films: We report on a strain-induced martensitic transformation, accompanied by a\nsuppression of magnetic order in epitaxial films of chemically disordered FeRh.\nX-ray diffraction, transmission electron microscopy and electronic structure\ncalculations reveal that the lowering of symmetry (from cubic to tetragonal)\nimposed by the epitaxial relation leads to a further, unexpected,\ntetragonal-to-orthorhombic transition, triggered by a band-Jahn-Teller-type\nlattice instability. The collapse of magnetic order is a direct consequence of\nthis structural change, which upsets the subtle balance between ferromagnetic\nnearest-neighbor interactions arising from Fe-Rh hybridization and frustrated\nantiferromagnetic coupling among localized Fe moments at larger distances."
    },
    {
        "anchor": "Effects of spin fluctuation on the magnetic anisotropy constant of\n  itinerant electron magnets: In the disordered local moment picture, we calculated the magnetization (M)\nand magnetic anisotropy energy (MAE) of FePt, CoPt, and MnAl ordered alloys and\nbody-centered tegragonal FeCo (bct-FeCo) disordered alloy, assuming spatially\nfluctuated spin configurations at finite temperatures. All alloys exhibit the\nrelation K1(T)/K1(0)=(M(T)/M(0))^n with the exponent (n) around 2. This is\nconsistent with the two-ion anisotropy model, in contrast to the usual\nsingle-ion anisotropy model exhibiting n=3. Because these systems have\ndifferent mechanisms of MAE, we suggest that this relation is a general rule\nfor itinerant electron systems.",
        "positive": "Electron emission from plasmonically induced Floquet bands at metal\n  surfaces: We explore the possibility of existence of plasmonically generated electronic\nFloquet bands at metal surfaces by studying the gauge transformed\nelectron-surface plasmon interaction in the prepumped plasmonic coherent state\nenvironment. These bands may promote non-Einsteinian electron emission from\nmetal surfaces exposed to primary interactions with strong electromagnetic\nfields. Resonant behaviour and scaling of emission yield with the parent\nelectronic structure and plasmonic state parameters are estimated for Ag(111)\nsurface. Relative yield intensities from non-Einsteinian emission channels in\nphotoelectron spectra offer the means to calibrate the mediating plasmonic\nfields and therefrom ensuing surface Floquet bands."
    },
    {
        "anchor": "Towards a Microscopic Model of Magnetoelectric Interactions in Ni3V2O8: We develop a microscopic magnetoelectric coupling in Ni$_3$V$_2$O$_8$ (NVO)\nwhich gives rise to the trilinear phenomenological coupling used previously to\nexplain the phase transition in which magnetic and ferroelectric order\nparameters appear simultaneously. Using combined neutron scattering\nmeasurements and first-principles calculations of the phonons in NVO, we\ndetermine eleven phonons which can induce the observed spontaneous\npolarization. Among these eleven phonons, we find that a few of them can\nactually induce a significant dipole moment. Using the calculated atomic\ncharges, we find that the required distortion to induce the observed dipole\nmoment is very small (~0.001 \\AA) and therefore it would be very difficult to\nobserve the distortion by neutron-powder diffraction. Finally, we identify the\nderivatives of the exchange tensor with respect to atomic displacements which\nare needed for a microscopic model of a spin-phonon coupling in NVO and which\nwe hope will be obtained from a fundamental quantum calculation such as LDA+U.\nWe also analyze two toy models to illustrate that the Dzyaloskinskii-Moriya\ninteraction is very important for coexisting of magnetic and ferroelectric\norder but it is not the only mechanism when the local site symmetry of the\nsystem is low enough.",
        "positive": "Conical intersections induced by the Renner effect in polyatomic\n  molecules: Characterizing and localizing electronic energy degeneracies is important for\ndescrib-ing and controlling electronic energy flow in molecules. We show, using\ntopological phase considerations that the Renner effect in polyatomic molecules\nwith more than 3 nuclei is necessarily accompanied by 'satellite' conical\nintersections. In these intersections the non-adiabatic coupling term is on the\naverage half an integer. We present ab-inito results on the tetra-atomic\nradical cation C2H2+ to demonstrate the theory"
    },
    {
        "anchor": "Magnetism, symmetry and spin transport in van der Waals layered systems: The discovery of an ever increasing family of atomic layered magnetic\nmaterials, together with the already established vast catalogue of strong\nspin-orbit coupling (SOC) and topological systems, calls for some guiding\nprinciples to tailor and optimize novel spin transport and optical properties\nat their interfaces. Here we focus on the latest developments in both fields\nthat have brought them closer together and make them ripe for future fruitful\nsynergy. After outlining fundamentals on van der Waals (vdW) magnetism and SOC\neffects, we discuss how their coexistence, manipulation and competition could\nultimately establish new ways to engineer robust spin textures and drive the\ngeneration and dynamics of spin current and magnetization switching in 2D\nmaterials-based vdW heterostructures. Grounding our analysis on existing\nexperimental results and theoretical considerations, we draw a prospective\nanalysis about how intertwined magnetism and spin-orbit torque (SOT) phenomena\ncombine at interfaces with well-defined symmetries, and how this dictates the\nnature and figures-of-merit of SOT and angular momentum transfer. This will\nserve as a guiding role in designing future non-volatile memory devices that\nutilize the unique properties of 2D materials with the spin degree of freedom.",
        "positive": "Magnetic resonance studies of the fundamental spin-wave modes in\n  individual submicron Cu/NiFe/Cu perpendicularly magnetized disks: Spin wave spectra of perpendicularly magnetized disks with trilayers\nconsisting of a 100 nm permalloy (Py) layer sandwiched by two Cu layers of 30\nnm, are measured individually with a Magnetic Resonance Force Microscope\n(MRFM). It is demonstrated by 3D micromagnetic simulations that in disks having\nsub-micron size diameters, the lowest energy spin wave mode of the saturated\nstate is not spatially uniform but rather is localized at the center of the\nPy/Cu interface in the region of a minimum demagnetizing field."
    },
    {
        "anchor": "Advancing CMOS with Carbon Electronics: A fresh look on carbon-based transistor channel materials like single-walled\ncarbon nanotubes (CNT) and graphene nanoribbons (GNR) in future electronic\napplications is given. Although theoretical predictions initially promised that\nGNR (which do have a bandgap) would perform equally well as transistors based\non CNTs, experimental evidence for the well-behaved transistor action is\nmissing up to now. Possible reasons for the shortcomings as well as possible\nsolutions to overcome the performance gap will be addressed. In contrast to\nGNR, short channel CNT field effect transistors (FET) demonstrate in the\nexperimental realization almost ideal transistor characteristics down to very\nlow bias voltages. Therefore, CNT-FETs are clear frontrunners in the search of\na future CMOS switch, that will enable further voltage and gate length scaling.\nEssential features which distinguish CNT-FETs from alternative solution will be\ndiscussed and benchmarked. Finally, the gap to industrial wafer-level scale\nSWCNT integration will be addressed and strategies for achieving highly aligned\ncarbon nanotube fabrics will be discussed. Without such a high yield\nwafer-scale integration, SWCNT circuits will be an illusionary dream.",
        "positive": "Lattice Vibrational Modes and Raman Scattering Spectra of Strained\n  Phosphorene: Strain is prominent in fabricated samples of two-dimensional semiconductors\nand it also serves as an exploitable tool for engineering their properties.\nHowever, quantifying strain and characterizing its spatially inhomogeneous\ndistribution across a material are challenging tasks. Here, we report the\nlattice vibrational modes and corresponding Raman spectra of strained monolayer\nblack phosphorus (phosphorene) by first-principles simulations. We show that\nfrequencies of vibrational modes of phosphorene and their Raman scattering\npeaks exhibit substantial and distinct shifts according to the types and size\nof strain. Therefore, combined with high spatial-resolution Raman scattering\nmeasurements, our calculated results can quantify strain distributions in\nphosphorene. This information is essential for understanding structures of\nfuture large-scale fabrication and strain engineering of phosphorene."
    },
    {
        "anchor": "Effect of annealing on spinodally decomposed Co2CrAl grown via floating\n  zone technique: Among the large class of Heusler compounds, Co2CrAl is predicted to be 100 %\nspin polarized and is hence, a potential candidate for application in\nspintronics. So far, the predicted properties have not been experimentally\nrealized which may be attributed to the phase segregated nature of samples.\nThis phase segregation is avoided using floating zone growth. However, the\ngrown sample was found to have undergone phase transformation via spinodal\ndecomposition at low temperatures. In the present work, thermal annealing has\nbeen done on the spinodally decomposed samples and its effect on\nmicrostructure, crystallographic structure and magnetic properties has been\nstudied. Annealing experiments were done and analyzed in order to understand\nthe extent of the solid state miscibility gap. With regards to the phase\ndiagram, the two-phase regime was found to extend till 1000 {\\deg}C. Even at\n1250 {\\deg}C, we are still inside the immiscibility region. The thermodynamic\nmiscibility gap was thus found to exist until high temperatures and alternate\nroutes might be required to obtain a single phase sample with the desired high\nspin polarization and Curie temperature in the Co-Cr-Al system.",
        "positive": "Two-Dimensional Semiconducting Metal Organic Frameworks with Auxetic\n  Effect, Room Temperature Ferrimagnetism, Chiral Ferroelectricity, Bipolar\n  Spin Polarization and Topological Nodal Lines/Points: Two-dimensional (2D) semiconductors integrated with two or more functions are\nthe cornerstone for constructing multifunctional nanodevices, but remain\nlargely limited. Here, by tuning the spin state of organic linkers and the\nsymmetry/topology of crystal lattice, we predict a class of unprecedented\nmultifunctional semiconductors in 2D Cr(II) five-membered heterocyclic metal\norganic frameworks that simultaneously possess auxetic effect, room temperature\nferrimagnetism, chiral ferroe-lectricity, electrically reversible spin\npolarization and topological nodal lines/points. Taking 2D Cr(TDZ)$_2$\n(TDZ=1.2.5-thiadiazole) as an exemplification, the auxetic effect is produced\nby the anti-tetra-chiral lattice structure. The high temperature ferrimagnetism\noriginates from the strong d-p direct magnetic exchange interaction between Cr\ncations and TDZ doublet radical anions. Meanwhile, the\nclockwise-counterclockwise alignment of TDZ' dipoles results in unique 2D\nchiral ferroelectricity with atomic-scale vortex-antivortex states. 2D\nCr(TDZ)$_2$ is an intrinsic bipolar magnetic semiconductor where half-metallic\nconduction with switchable spin-polarization direction can be induced by\napplying a gate voltage. Besides, the symmetry of the little group C$_4$ of\nlattice structure endows 2D Cr(TDZ)$_2$ with topological nodal lines and a\nquadratic nodal point in the Brillouin zone near the Fermi level."
    },
    {
        "anchor": "Thermoelectric performance in electron and hole doped PtSb$_2$: We employ density functional theory to investigate the thermoelectric\nproperties of electron and hole doped PtSb$_2$. Our results show that for\ndoping of 0.04 holes per unit cell (1.5$\\times10^{20}$ cm$^{-3}$) PtSb$_2$\nshows a high Seebeck coefficient at room temperature, which can also be\nachieved at other temperatures by controlling the carrier concentration (both\nelectron and hole). The electrical conductivity becomes temperature independent\nwhen the doping exceeds about 0.20 electrons/holes per unit cell. The figure of\nmerit at 800 K in electron and hole doped PtSb$_2$ is 0.13 and 0.21,\nrespectively. The thermoelectric efficiency with same host material are\npredicted for certain doping levels.",
        "positive": "Interdot Coulomb repulsion effect on the charge transport of parallel\n  double single electron transistors: The charge transport behaviors of parallel double single electron transistors\n(SETs) are investigated by the Anderson model with two impurity levels. The\nnonequilibrium Keldysh Green's technique is used to calculate the\ncurrent-voltage characteristics of system. For SETs implemented by quantum dots\n(QDs) embedded into a thin $SiO_2$ layer, the interdot Coulomb repulsion is\nmore important than the interdot electron hopping as a result of high potential\nbarrier height between QDs and $SiO_2$. We found that the interdot Coulomb\nrepulsion not onlyleads to new resonant levels, but also creates negative\ndifferential conductances."
    },
    {
        "anchor": "Increase of the mean inner Coulomb potential in Au clusters induced by\n  surface tension and its implication for electron scattering: Electron holography in a transmission electron microscope was applied to\nmeasure the phase shift induced by Au clusters as a function of the cluster\nsize. Large phase shifts Df observed for small Au clusters cannot be described\nby the well-known equation Df=C_E V_0 t (C_E: interaction constant, V_0: mean\ninner Coulomb potential (MIP) of bulk gold, t: cluster thickness). The rapid\nincrease of the Au MIP with decreasing cluster size derived from Df, can be\nexplained by the compressive strain of surface atoms in the cluster.",
        "positive": "Topological Edge and Corner States in Biphenylene Network: The electronic states and topological properties of the biphenylene network\n(BPN) are analyzed using a tight-binding model based on the $\\pi$-electron\nnetwork. It is shown that tuning the hopping parameters induces topological\nphase transitions, leading to the emergence of edge states owing to the\nnontrivial topological Zak phase of the bulk BPN. Elementary band analysis\nclearly gives the number of edge states, which are associated with the location\nof Wannier centers. In addition, we have presented the conditions for the\nemergence of corner states owing to the higher-order topological nature of BPN."
    },
    {
        "anchor": "Band engineering in graphene with superlattices of substitutional\n  defects: We investigate graphene superlattices of nitrogen and boron substitutional\ndefects and by using symmetry arguments and electronic structure calculations\nwe show how such superlattices can be used to modify graphene band structure.\nSpecifically, depending on the superlattice symmetry, the structures considered\nhere can either preserve the Dirac cones (D_{6h} superlattices) or open a band\ngap (D_{3h}). Relevant band parameters (carriers effective masses, group\nvelocities and gaps, when present) are found to depend on the superlattice\nconstant n as 1/n^{p} where p is in the range 1-2, depending on the case\nconsidered. Overall, the results presented here show how one can tune the\ngraphene band structure to a great extent by modifying few superlattice\nparameters.",
        "positive": "Synchrotron x-ray diffraction studies of the $\u03b1\\rightleftharpoons\n  \u03b2$ structural phase transition in Sn and Sn-Cu: The transformation between the metallic ($\\beta$) and semi-conducting\n($\\alpha$) allotropes of tin is still not well understood. The phase transition\ntemperature stated in the literature, 286.2 K, seems to be inconsistent with\nrecent calorimetric measurements. In this paper, this intriguing aspect has\nbeen explored in Sn and Sn-Cu (alloyed 0.5% Cu by weight) using temperature\nresolved synchrotron x-ray diffraction measurements performed at the Indus-2\nfacility. Additionally, the $\\alpha \\rightleftharpoons \\beta$ Sn transition has\nbeen recorded using in-situ heating/cooling experiments in a scanning electron\nmicroscope. Based on these measurements, a protocol has been suggested to\nreduce the formation of $\\alpha$-Sn in potentially susceptible systems. This\nwill be useful in experiments like TIN.TIN (The INdia-based TIN detector),\nwhich proposes to employ ~100 - 1000 kg of superconducting tin-based detectors\nto search for neutrinoless double beta decay in the isotope $^{124}$Sn."
    },
    {
        "anchor": "Unidirectional Synapse-Like Behavior of Zr/ZrO2-NT/Au Layered Structure: Zirconia nanotubular layer with an outer tube diameter 25 nm was synthesized\nby potentiostatic anodization. The Zr/ZrO2-NT/Au memristive structure is\nfabricated using stencil mask and magnetron sputtering techniques.\nCurrent-voltage characteristics are measured in full cycles of resistive\nswitching with varying parameters of the applied harmonic voltage. An\nequivalent circuit with unidirectional electrical conductivity for the studied\nstructure is proposed. Estimates of the electrical resistance of memristors in\nhigh-and intermediate resistivity states are performed. The high synaptic\nplasticity of memristors based on the Zr/ZrO2-NT/Au structure is shown.",
        "positive": "Perovskite Twin Solar Device with Estimated 50% Bifacial PCE Potential\n  and New Solar Material Options: There are recent investigations regarding tandem solar cells with a top\nperovskite cell and a bottom silicon one with a potential of > 25% power\nconversion efficiency. Because of still high production costs of silicon cells\nit is believed that this tandem cell does not satisfy future requirements. Here\nthe construction of a low-cost FAPbI3 twin solar cell is proposed with assumed\nPCE of 30%. With an ingenious rear illumination even 50% bifacial power\nconversion efficiency should be feasible. Importantly, a single twin cell can\ndeliver the minimum potential difference of 1.7 V to conduct water splitting in\npractice. Avoiding additional electrodes, the twin cell device may be expanded\nby a large band gap sensitizer film at the mirror plan, derived from known\nelectrically isolating phosphor storage materials that can capture otherwise\nwasted high-energetic radiation. Further, the substitution ot TiO2 (rutile) by\nferroelectric and photo-catalytically active Bi2SiO5 with its comparable energy\ngap is sugested. CuO1-x could serve as new back electrode material due to its\nhigh electric conductivity. In addition, an environmentally benign\n(Cs,FA)2(Na,Cu,Ag)Bi(I,Br)6 elpasolite solar absorber material is discussed.\nAlternatively, pyroelectric hexagonal bismuth sulfide iodide with its complex\nsuperstructure may deliver a promising multiple band gap feature with suggested\nsinglet fission capability as intrinsic property to overcome its lower\nefficiency."
    },
    {
        "anchor": "Pair distribution function analysis driven by atomistic simulations:\n  Application to microwave radiation synthesized TiO$_2$ and ZrO$_2$: A workflow is presented for performing pair distribution function (PDF)\nanalysis of defected materials using structures generated from atomistic\nsimulations. A large collection of structures, which differ in the types and\nconcentrations of defects present, are obtained through energy minimization\nwith an empirical interatomic potential. Each of the structures is refined\nagainst an experimental PDF. The structures with the lowest goodness of fit\n$R_w$ values are taken as being representative of the experimental structure.\nThe workflow is applied to anatase titanium dioxide ($a$-TiO$_2$) and\ntetragonal zirconium dioxide ($t$-ZrO$_2$) synthesized in the presence of\nmicrowave radiation, a low temperature process that generates disorder. The\nresults suggest that titanium vacancies and interstitials are the dominant\ndefects in $a$-TiO$_2$, while oxygen vacancies dominate in $t$-ZrO$_2$.\nAnalysis of the atomic displacement parameters extracted from the PDF\nrefinement and mean squared displacements calculated from molecular dynamics\nsimulations indicate that while these two quantities are closely related, it is\nchallenging to make quantitative comparisons between them. The workflow can be\napplied to other materials systems, including nanoparticles.",
        "positive": "Finite-size effects of electron transport in PdCoO$_2$: A wide range of unconventional transport phenomena have recently been\nobserved in single-crystal delafossite metals. Here, we present a theoretical\nframework to elucidate electron transport using a combination of\nfirst-principles calculations and numerical modeling of the anisotropic\nBoltzmann transport equation. Using PdCoO$_2$ as a model system, we study\ndifferent microscopic electron and phonon scattering mechanisms and establish\nthe mean free path hierarchy of quasiparticles at different temperatures. We\ntreat the anisotropic Fermi surface explicitly to numerically obtain\nexperimentally-accessible transport observables, which bridge between the\n\"diffusive\", \"ballistic\", and \"hydrodynamic\" transport regime limits. We\nillustrate that distinction between the \"quasi-ballistic\", and\n\"quasi-hydrodynamic\" regimes is challenging and often needs to be quantitative\nin nature. From first-principles calculations, we populate the resulting\ntransport regime plots, and demonstrate how the Fermi surface orientation adds\ncomplexity to the observed transport signatures in micro-scale devices. Our\nwork provides key insights into microscopic interaction mechanisms on open\nhexagonal Fermi surfaces and establishes their connection to the macroscopic\nelectron transport in finite-size channels."
    },
    {
        "anchor": "A direct comparison of CVD-grown and exfoliated MoS2 using optical\n  spectroscopy: MoS2 is a highly interesting material system, which exhibits a crossover from\nan indirect band gap in the bulk crystal to a direct gap for single layers.\nHere, we perform a direct comparison between large-area MoS$_2$ films grown by\nchemical vapor deposition (CVD) and MoS$_2$ flakes prepared by mechanical\nexfoliation from natural bulk crystal. Raman spectroscopy measurements show\ndifferences between the in-plane and out-of-plane phonon mode positions in\nCVD-grown and exfoliated MoS$_2$. Photoluminescence (PL) mapping reveals large\nregions in the CVD-grown films that emit strong PL at room temperature, and\nlow-temperature PL scans demonstrate a large spectral shift of the A exciton\nemission as a function of position. Polarization-resolved PL measurements under\nnear-resonant excitation conditions show a strong circular polarization of the\nPL, corresponding to a valley polarization.",
        "positive": "Electron transport in real time from first-principles: While the vast majority of calculations reported on molecular conductance\nhave been based on the static non-equilibrium Green's function formalism\ncombined with density functional theory, in recent years a few time-depedent\napproaches to transport have started to emerge. Among these, the driven\nLiouville-von Neumann equation (J. Chem. Phys. 124, 214708 (2006)) is a simple\nand appealing route relying on a tunable rate parameter, which has been\nexplored in the context of semi-empirical methods. In the present study, we\nadapt this formulation to a density functional theory framework and analyze its\nperformance. In particular, it is implemented in an efficient all-electron DFT\ncode with Gaussian basis functions, suitable for quantum-dynamics simulations\nof large molecular systems. At variance with the case of the tight-binding\ncalculations reported in the literature, we find that now the initial\nperturbation to drive the system out of equilibrium plays a fundamental role in\nthe stability of the electron dynamics, and that the equation of motion used in\nprevious tight-binding implementations has to be modified to conserve the total\nnumber of particles during time propagation. Moreover, we propose a procedure\nto get rid of the dependence of the current-voltage curves on the rate\nparameter. This method is employed to obtain the current-voltage characteristic\nof saturated and unsaturated hydrocarbons of different lenghts, with very\npromising prospects."
    },
    {
        "anchor": "Genetic programming-based learning of carbon interatomic potential for\n  materials discovery: Efficient and accurate interatomic potential functions are critical to\ncomputational study of materials while searching for structures with desired\nproperties. Traditionally, potential functions or energy landscapes are\ndesigned by experts based on theoretical or heuristic knowledge. Here, we\npropose a new approach to leverage strongly typed parallel genetic programming\n(GP) for potential function discovery. We use a multi-objective evolutionary\nalgorithm with NSGA-III selection to optimize individual age, fitness, and\ncomplexity through symbolic regression. With a DFT dataset of 863 unique carbon\nallotrope configurations drawn from 858 carbon structures, the generated\npotentials are able to predict total energies within $\\pm 7.70$ eV at low\ncomputational cost while generalizing well across multiple carbon structures.\nOur code is open source and available at\n\\url{http://www.github.com/usccolumbia/mlpotential",
        "positive": "Ab initio variational approach for evaluating lattice thermal\n  conductivity: We present a first-principles theoretical approach for evaluating the lattice\nthermal conductivity based on the exact solution of the Boltzmann transport\nequation. We use the variational principle and the conjugate gradient scheme,\nwhich provide us with an algorithm faster than the one previously used in\nliterature and able to always converge to the exact solution. Three-phonon\nnormal and umklapp collision, isotope scattering and border effects are\nrigorously treated in the calculation. Good agreement with experimental data\nfor diamond is found. Moreover we show that by growing more enriched diamond\nsamples it is possible to achieve values of thermal conductivity up to three\ntimes larger than the commonly observed in isotopically enriched diamond\nsamples with 99.93% C12 and 0.07 C13."
    },
    {
        "anchor": "Anomalous Hall effect in Weyl semimetal half Heusler compounds RPtBi (R\n  = Gd and Nd): Topological materials ranging from topological insulators to Weyl and Dirac\nsemimetals form one of the most exciting current fields in condensed-matter\nresearch. Many half-Heusler compounds, RPtBi (R= rare earth) have been\ntheoretically predicted to be topological semimetals. Among various topological\nattributes envisaged in RPtBi, topological surface states, chiral anomaly and\nplanar Hall effect have been observed experimentally. Here, we report on an\nunusual intrinsic anomalous Hall effect (AHE) in the antiferromagnetic Heusler\nWeyl semimetal compounds GdPtBi and NdPtBi that is observed over a wide\ntemperature range. In particular, GdPtBi exhibits an anomalous Hall\nconductivity of up to 60 ohm-1cm-1 and an anomalous Hall angle as large as 23%.\nMuon spin resonance (mu-SR) studies of GdPtBi indicate a sharp\nantiferromagnetic transition (T_N) at 9 K without any noticeable magnetic\ncorrelations above T_N. Our studies indicate that Weyl points in these\nhalf-Heuslers are induced by a magnetic field via exchange-splitting of the\nelectronic bands at or near to the Fermi energy which is the source of the\nchiral anomaly and the AHE.",
        "positive": "Sulfur Vacancy Related Optical Transitions in Graded Alloys of MoxW1-xS2\n  Monolayers: Engineering the electronic bandgap is of utmost importance in diverse domains\nranging from information processing and communication technology to sensing and\nrenewable energy applications. Transition metal dichalcogenides (TMDCs) provide\nan ideal platform for achieving this goal through techniques including\nalloying, doping, and creating in-plane or out-of-plane heterostructures. Here,\nwe report on the synthesis and characterization of atomically controlled\ntwo-dimensional graded alloy of MoxW1-xS2, wherein the center region is Mo rich\nand gradually transitions towards a higher concentration of W atoms at the\nedges. This unique alloy structure leads to a continuously tunable bandgap,\nranging from 1.85 eV in the center to 1.95 eV at the edges consistent with the\nlarger band gap of WS2 relative to MoS2. Aberration-corrected high-angle\nannular dark-field scanning transmission electron microscopy showed the\npresence of sulfur monovacancy, VS, whose concentration varied across the\ngraded MoxW1-xS2 layer as a function of Mo content with the highest value in\nthe Mo rich center region. Optical spectroscopy measurements supported by ab\ninitio calculations reveal a doublet electronic state of VS, which was split\ndue to the spin-orbit interaction, with energy levels close to the conduction\nband or deep in the band gap depending on whether the vacancy is surrounded by\nW atoms or Mo atoms. This unique electronic configuration of VS in the alloy\ngave rise to four spin-allowed optical transitions between the VS levels and\nthe valence bands. Our work highlights the potential of simultaneous defect and\noptical engineering of novel devices based on these 2D monolayers."
    },
    {
        "anchor": "Optical representation of thermal nuclear fluctuation effect on band-gap\n  renormalization: The bandgap of insulating materials is renormalized in various ways by the\nelectron-phonon interaction owing to the dynamical and quantum fluctuations of\nnuclei. These fluctuation effects are considered in the perturbative\nAllen-Heine-Cardona theory using the formulae for the Fan-Migdal and\nDebye-Waller terms. However, the material dependence is not clear in the\nformulae. Thus, in this study, we focus on the analytical form of the\nDebye-Waller term and find that the term can be reformulated using the momentum\nmatrix. In addition, the optical selection rule is found to play a role. For\ndiamond-type materials, the Debye-Waller term can be approximately decomposed\ninto a product of the optical transition energy, the mean square displacement\nof nuclei, and the dipole transition probability. The decomposition can also be\napplied with an additional approximation to zinc-blende-type materials, as\nrevealed by our first-principles calculation. The magnitudes of the\nDebye-Waller term of several materials can thus be estimated using basic\nphysical quantities prior to performing the calculation of the electron-phonon\ninteraction.",
        "positive": "Large-Area High-Throughput Identification and Quality Control of\n  Graphene and Few-Layer Graphene: Prospects of Industry-Scale Applications: Practical applications of graphene require a reliable high-throughput method\nof graphene identification and quality control, which can be used for\nlarge-scale substrates and wafers. We have proposed and experimentally tested a\nfast and fully automated approach for determining the number of atomic planes\nin graphene samples. The procedure allows for in situ identification of the\nborders of the regions with the same number of atomic planes. It is based on an\noriginal image processing algorithm, which utilizes micro-Raman calibration,\nlight background subtraction, lighting non-uniformity correction, and the color\nand grayscale image processing for each pixel. The outcome of the developed\nprocedure is a pseudo-color map, which marks the single-layer and few-layer\ngraphene regions on the substrate of any size that can be captured by an\noptical microscope. Our approach works for various substrates, and can be\napplied to the mechanically exfoliated, chemically derived, deposited or\nepitaxial graphene on an industrial scale."
    },
    {
        "anchor": "Novel low-energy collective excitation at metal surfaces: A novel collective excitation is predicted to exist at metal surfaces where a\ntwo-dimensional surface-state band coexists with the underlying\nthree-dimensional continuum. This is a low-energy acoustic plasmon with linear\ndispersion at small wave vectors. Since new modern spectroscopies are\nespecially sensitive to surface dynamics near the Fermi level, the existence of\nsurface-state induced acoustic plasmons is expected to play a key role in a\nlarge variety of new phenomena and to create situations with potentially new\nphysics.",
        "positive": "Inverse magnetocaloric effect in ferromagnetic Sm0.6-xLaxSr0.4MnO3 due\n  to 4f-3d exchange interaction: We report magnetic and magnetocaloric properties of Sm0.6-xLaxSr0.4MnO3 (x =\n0-0.6). A rapid increase around TC and an anomalous peak at a temperature\nT*<<TC occur in magnetization which lead to normal and inverse magnetocaloric\neffects (MCE), respectively. While TC increases with increasing x (TC=118 K for\nx=0 and TC=363 K for x=0.6), T* increases from 30 K (x=0) to 120 K (x=0.4) and\nthen decreases to 105 K (x=0.5). The \\DeltaSm reaches +1.07 Jkg-1K-1 at 10 K\nand -4 Jkg-1K-1 around TC in x=0.4 for \\Delta H=5T. The inverse MCE is\nattributed to antiferromagnetic coupling between Sm-4f and Mn-3d magnetic\nmoments."
    },
    {
        "anchor": "Lattice distortion and atomic displacements during the fcc/bcc\n  martensitic transformation: From our previous models of martensitic transformation, the continuous\nmatrices of atomic displacements and lattice deformations from\nface-centred-cubic (fcc) to body centred-cubic (bcc) phases are calculated in\nagreement with different possible final orientation relationships, such as\nBain, Pitsch and Kurdjumov-Sachs (KS). The angular distortion introduced in the\ncalculations appears a natural order parameter of transition. The distortion\ncorresponding to KS is the only one that respects the parallelism of a dense\ndirection and of a dense plane of both the fcc and bcc phases. This paper gives\nan alternative to the classical crystallographic theories and shear concepts\nassociated to martensitic transformations.",
        "positive": "Understanding the Origin of the Low Cure-Shrinkage of Polybenzoxazine\n  Resin by Computational Simulation: Thermoset resin-based composite materials are widely used in the aerospace\nindustry, mainly due to their high stiffness-to-weight and strength-to-weight\nratios. A major issue with the use of thermoset resins in fiber composites is\nthe process-induced residual stresses that are formed from resin chemical\nshrinkage during the curing process. These residual stresses within the\ncomposite material ultimately result in reduced durability and residual\ndeformations of the final product. Polybenzoxazine (PBZ) polymer resins have\ndemonstrated near-zero volumetric shrinkage during the curing process. Although\nthe low shrinkage of PBZ is promising in terms of reduced process-induced\nresidual stresses, little is known about the physical causes. In this work,\nMolecular Dynamics (MD) simulations are performed with a reactive force field\nto predict physical properties (gelation point, evolution of network, mass\ndensity, volumetric shrinkage) and mechanical properties (Bulk modulus, Shear\nmodulus, Young's modulus, Poisson's ratio, Yield strength) as a function of\ncrosslinking density. The MD modeling procedure is validated herein using\nexperimental measurements of the modeled PBZ resin. The results of this study\nare used to provide a physical understanding of the zero-shrinkage phenomenon\nof PBZ. This information is also a critical input to future process modeling\nefforts for PBZ composites."
    },
    {
        "anchor": "Strain-dependent modulation of conductivity in single layer\n  transition-metal dichalcogenides: Quantum conductance calculations on the mechanically deformed monolayers of\nMoS$_2$ and WS$_2$ were performed using the non-equlibrium Green's functions\nmethod combined with the Landauer-B\\\"{u}ttiker approach for ballistic transport\ntogether with the density-functional based tight binding (DFTB) method. Tensile\nstrain and compression causes significant changes in the electronic structure\nof TMD single layers and eventually the transition semiconductor-metal occurs\nfor elongations as large as ~11% for the 2D-isotropic deformations in the\nhexagonal structure. This transition enhances the electron transport in\notherwise semiconducting materials.",
        "positive": "Noncollinear topological textures in two-dimensional van der Waals\n  materials: From magnetic to polar systems: In recent years, noncollinear topological textures have long gained\nincreasing research attentions for their high values of both fundamental\nresearches and potential applications. The recent discovery of intrinsic orders\nin magnetic and polar two-dimensional van der Waals materials provides a new\nideal platform for the investigation of noncollinear topological textures.\nHere, we review the theoretical and experimental progresses on noncollinear\ntopological textures in two-dimensional van der Waals materials in very recent\nyears. During these years, magnetic skyrmions of both Bloch and N\\'eel types\nhave been observed experimentally in a few two-dimensional van der Waals\nmaterials and related heterostructures. Concurrently, more theoretic\npredictions basing on various mechanisms have been reported about different\nnoncollinear topological textures in two-dimensional van der Waals materials,\nsuch as skyrmions, bimerons, anti-biskyrmions and skyrmionium, which are still\nwaiting to be confirmed in experiments. Besides, noncollinear topological\nelectric dipole orders have also been predicted in two-dimensional van der\nWaals materials. Taking advantage of the intrinsic two-dimensional nature and\nhigh integratability, the two-dimensional van der Waals materials will play an\nimportant role in the investigation on noncollinear topological textures in\nboth magnetic and polar systems."
    },
    {
        "anchor": "Tuning of the Dzyaloshinskii-Moriya Interaction by He$^+$ ion\n  irradiation: We studied the impact of He$^+$ irradiation on the Dzyaloshinskii-Moriya\ninteraction (DMI) in Ta/Co20Fe60B20/Pt/MgO samples. We found that irradiation\nwith of 40 keV He$^+$ ions increases DMI by approximately 20% for fluences up\nto 2$\\cdot$10$\\rm{^{16}}$ $\\rm{ions/cm}^2$ before it decreases for higher\nfluence values. In contrast, the interfacial anisotropy shows a distinctly\ndifferent fluence dependence. To better understand the impact of the ion\nirradiation on the Ta and Pt interfaces with the Co20Fe60B20 layer, we carried\nout Monte-Carlo simulations, which showed an expected increase of disorder at\nthe interfaces. A moderate increase in disorder can increase the total number\nof triplets for the three-site exchange mechanism and can consequently increase\nthe DMI. Our results demonstrate that the DMI can be locally engineered at the\nnanometer scale, providing a highly promising approach to advance\nskyrmion-based memories.",
        "positive": "Bloch line dynamics within moving domain walls in 3D ferromagnets: We study field-driven magnetic domain wall dynamics in garnet strips by\nlarge-scale three-dimensional micromagnetic simulations. The domain wall\npropagation velocity as a function of the applied field exhibits a low-field\nlinear part terminated by a sudden velocity drop at a threshold field\nmagnitude, related to the onset of excitations of internal degrees of freedom\nof the domain wall magnetization. By considering a wide range of strip\nthicknesses from 30 nm to 1.89 $\\mu$m, we find a non-monotonic thickness\ndependence of the threshold field for the onset of this instability, proceeding\nvia nucleation and propagation of Bloch lines within the domain wall. We\nidentify a critical strip thickness above which the velocity drop is due to\nnucleation of horizontal Bloch lines, while for thinner strips and depending on\nthe boundary conditions employed, either generation of vertical Bloch lines, or\nclose-to-uniform precession of the domain wall internal magnetization takes\nplace. For strips of intermediate thicknesses, the vertical Bloch lines assume\na deformed structure due to demagnetizing fields at the strip surfaces,\nbreaking the symmetry between the top and bottom faces of the strip, and\nresulting in circulating Bloch line dynamics along the perimeter of the domain\nwall."
    },
    {
        "anchor": "Double Au rows on Si(553) surface: A new structural model of Au induced Si(553) surface is proposed. The model\naccounts for recently experimentally found value of the Au coverage, i.e. 0.48\nmonolayer, which suggests formation of two gold chains on each Si(553) terrace.\nThe resulting structural model, like the models of other vicinal Si surfaces,\nfeatures the honey-comb chain, but there is no buckling at step edge, which is\nobserved on Si(335)-Au and Si(557)-Au surfaces. The present model is more\nstable than the models with single Au chain only, and agrees very well with\nexisting experimental data. In particular, calculated band structure, featuring\ntwo metallic bands coming from hybridization of the gold in both chains with\nneighboring Si atoms, perfectly matches the photoemission data. Moreover,\ntheoretical scanning tunneling microscopy topography remains in excellent\nagreement with the experiment.",
        "positive": "Optical Emission from Light-like and Particle-like Excitons in Monolayer\n  Transition Metal Dichalcogenides: Several monolayer transition metal dichalcogenides (TMDs) are direct band gap\nsemiconductors and potentially efficient emitters in light emitting devices.\nPhotons are emitted when strongly bound excitons decay radiatively, and\naccurate models of such excitons are important for a full understanding of the\nemission. Importantly, photons are emitted in directions uniquely determined by\nthe exciton center of mass momentum and with lifetimes determined by the\nexciton transition matrix element. The exciton band structures of\ntwo-dimensional hexagonal materials, including TMDs, are highly unusual with\ncoexisting particle- and light-like bands. The latter is non-analytic with\nemission selection rules essentially opposite to the particle-like states, but\nhas been ignored in analyses of TMD light emission so far. In the present work,\nwe analyse the temperature and angular dependence of light emission from both\nexciton species and point out several important consequences of the unique\nexciton band structure. Within a first-principles\nDensity-Functional-Theory+Bethe-Salpeter-Equation framework, we compute exciton\nband structures and optical matrix elements for the important TMDs MoS2, MoSe2,\nWS2, and WSe2. At low temperature, only the particle-like band is populated and\nour results agree with previous work. However, at slightly elevated\ntemperatures, a significant population of the light-like band leads to modified\nangular emission patterns and lifetimes. Clear experimental fingerprints are\npredicted and explained by a simple four-state model incorporating spin-orbit\nas well as intervalley exchange coupling."
    },
    {
        "anchor": "Two-Dimensional Multiferroic Semiconductors with Coexisting\n  Ferroelectricity and Ferromagnetism: Low-dimensional multiferroicity, though highly scarce in nature, has\nattracted great attention due to both fundamental and technological interests.\nUsing first-principles density functional theory, we show that ferromagnetism\nand ferroelectricity can coexist in monolayer transition metal phosphorus\nchalcogenides (TMPCs) - CuMP$_2$X$_6$ (M=Cr, V; X=S, Se). These van der Waals\nlayered materials represent a class of 2D multiferroic semiconductors that\nsimultaneously possess ferroelectric and ferromagnetic orders. In these\nmonolayer materials, Cu atoms spontaneously move away from the center atomic\nplane, giving rise to nontrivial electric dipole moment along the plane normal.\nIn addition, their ferromagnetism originates from indirect exchange interaction\nbetween Cr/V atoms, while their out-of-plane ferroelectricity suggests the\npossibility of controlling electric polarization by external vertical electric\nfield. Monolayer semiconducting TMPCs thus provide a solid-state 2D materials\nplatform for realizing 2D nanoscale switches and memory devices patterned with\ntop and bottom electrodes.",
        "positive": "Resistive Switching Phenomena of HfO2 Films Grown by MOCVD for Resistive\n  Switching Memory Devices: The resistive switching phenomena of HfO2 films grown by metalorganic\nchemical vapor deposition was studied for the application of ReRAM devices. In\nthe fabricated Pt/HfO2/TiN memory cells, the bipolar resistive switching\ncharacteristics were observed, and the set and reset states were measured to be\nas low as 7 uA and 4 uA, respectively, at VREAD = 1 V. Regarding the resistive\nswitching performance, the stable RS performance was observed under 40\nrepetitive dc cycling test with the small variations of set/reset voltages and\ncurrents, and good retention characteristics over 105 s in both LRS and HRS.\nThese results show the possibility of MOCVD grown HfO2 films as a promising\nresistive switching materials for ReRAM applications."
    },
    {
        "anchor": "The effect of mechanical stress on lithium distribution and geometry\n  optimisation for multi-material lithium-ion anodes: A model is presented for predicting the open-circuit voltage (OCV) and\nlithium distribution within lithium-ion anodes containing multiple materials,\ncoupling linear elasticity with a stress-dependent chemical potential. The\nmodel is applied to a spherical radially-symmetric nano-particle with a silicon\ncore and a graphite shell, highlighting the large effect on lithium\ndistribution and OCV caused by the stress-coupling. Various performance\nmeasures based on the expanded volume, the amount of lithium intercalated and\nthe maximum stress induced, are calculated for a silicon core with a graphite\nshell to enable optimisation of the volume of the silicon core.",
        "positive": "First-principles based Landau-Devonshire potential for BiFeO$_3$: The work describes a first-principles-based computational strategy for\nstudying structural phase transitions, and in particular, for determination of\nthe so-called Landau-Devonshire potential - the classical zero-temperature\nlimit of the Gibbs energy, expanded in terms of order parameters. It exploits\nthe configuration space attached to the eigenvectors of the modes frozen in the\nground state, rather than the space spanned by the unstable modes of the\nhigh-symmetry phase, as done usually. This allows us to carefully probe the\npart of the energy surface in the vicinity of the ground state, which is most\nrelevant for the properties of the ordered phase. We apply this procedure to\nBiFeO$_3$ and perform ab-initio calculations in order to determine potential\nenergy contributions associated with strain, polarization and oxygen octahedra\ntilt degrees of freedom, compatible with its two-formula unit cell periodic\nboundary conditions."
    },
    {
        "anchor": "Driving non-trivial quantum phases in conventional semiconductors with\n  intense excitonic fields: Inducing novel quantum phases and topologies in materials using intense light\nfields is a key objective of modern condensed matter physics, but nonetheless\nfaces significant experimental challenges. Alternately, theory predicts that in\nthe dense limit, excitons - collective excitations composed of Coulomb-bound\nelectron-hole pairs - could also drive exotic quantum phenomena. However, the\ndirect observation of these phenomena requires the resolution of electronic\nstructure in momentum space in the presence of excitons, which became possible\nonly recently. Here, using time- and angle-resolved photoemission spectroscopy\nof an atomically thin semiconductor in the presence of a high-density of\nresonantly and coherently photoexcited excitons, we observe the\nBardeen-Cooper-Schrieffer (BCS) excitonic state - analogous to the Cooper pairs\nof superconductivity. We see the valence band transform from a conventional\nparaboloid into a Mexican-hat like Bogoliubov dispersion - a hallmark of the\nexcitonic insulator phase; and we observe the recently predicted giant\nexciton-driven Floquet effects. Our work realizes the promise that intense\nbosonic fields, other than photons, can also drive novel quantum phenomena and\nphases in materials.",
        "positive": "Magnetic properties of dense nanoparticle arrays with core/shell\n  morphology: We calculate the magnetization hysteresis for an ordered array of composite\nmagnetic nanoparticles with a ferromagnetic (FM) core and an antiferromagnetic\n(AFM) shell, located on a triangular lattice and coupled via magnetostatic\nforces. Each nanoparticle is described by a pair of exchange-coupled (J),\nanisotropic spins (Meiklejohn-Bean model). The magnetization hysteresis loop is\nobtained using the Metropolis Monte Carlo algorithm. For magnetically hard\nnanoparticles we find that the coercivity is reduced with increasing the\ndipolar coupling strength, while the exchange bias field shows an\nnon-monotonous behavior resulting from the competition between the random\nanisotropy and interparticle dipolar interactions. The possibility of enhancing\nthe exchange bias field by increasing the packing density is discussed."
    },
    {
        "anchor": "Localized Energy States Induced by Atomic-Level Interfacial Broadening\n  in Heterostructures: A theoretical framework incorporating atomic-level interfacial details is\nderived to include the electronic structure of buried interfaces and describe\nthe behavior of charge carriers in heterostructures in the presence of finite\ninterfacial broadening. Applying this model to ultrathin heteroepitaxial\n(SiGe)m/(Si)m superlattices predicts the existence of localized energy levels\nin the band structure induced by sub-nanometer broadening, which provides\nadditional paths for hole-electron recombination. These predicted interfacial\nelectronic transitions and the associated absorptive effects are confirmed\nexperimentally at variable superlattice thickness and periodicity. By mapping\nthe energy of the critical points, the optical transitions are identified\nbetween 2 and 2.5 eV thus extending the optical absorption to lower energies.\nThis phenomenon enables a straightforward and non-destructive probe of the\natomic-level broadening in heterostructures.",
        "positive": "Band Engineering of Dirac Semimetals using Charge Density Waves: New developments in the field of topological matter are often driven by\nmaterials discovery, including novel topological insulators, Dirac semimetals\nand Weyl semimetals. In the last few years, large efforts have been performed\nto classify all known inorganic materials with respect to their topology.\nUnfortunately, a large number of topological materials suffer from non-ideal\nband structures. For example, topological bands are frequently convoluted with\ntrivial ones, and band structure features of interest can appear far below the\nFermi level. This leaves just a handful of materials that are intensively\nstudied. Finding strategies to design new topological materials is a solution.\nHere we introduce a new mechanism that is based on charge density waves and\nnon-symmorphic symmetry to design an idealized Dirac semimetal. We then show\nexperimentally that the antiferromagnetic compound GdSb$_{0.46}$Te$_{1.48}$ is\na nearly ideal Dirac semimetal based on the proposed mechanism, meaning that\nmost interfering bands at the Fermi level are suppressed. Its highly unusual\ntransport behavior points to a thus far unknown regime, in which Dirac carriers\nwith Fermi energy very close to the node seem to gradually localize in the\npresence of lattice and magnetic disorder."
    },
    {
        "anchor": "Formation of ordered arrays of Ag nanowires and nanodots on Si(5 5 7)\n  surface: The ordered arrays of Ag nanowires and nanodots have been grown in ultra-high\nvacuum on the Si(5 5 7) surface containing regular steps of three bilayer\nheight. Formation of Ag nanostructures have been studied by scanning tunneling\nmicroscopy, low energy electron diffraction and Auger electron spectroscopy at\nroom temperature. It was shown that a sample exposure in the vacuum before Ag\ngrowth affects the shape of the forming Ag islands. This effect is caused by\noxygen adsorption on the silicon surface from the residual atmosphere in the\nvacuum chamber. When Ag is deposited on the clean silicon surface the islands,\noverlapping several (1 1 1) neighboring terraces, form. The arrays of silver\nnanowires elongated along steps and silver nanodots, arranged in lines parallel\nto the steps, can be formed on the Si(5 5 7) surface depending on the amount of\nadsorbed oxygen.",
        "positive": "Finite-size correction in many-body electronic structure calculations: Finite-size (FS) effects are a major source of error in many-body (MB)\nelectronic structure calculations of extended systems. A method is presented to\ncorrect for such errors. We show that MB FS effects can be effectively included\nin a modified local density approximation calculation. A parametrization for\nthe FS exchange-correlation functional is obtained. The method is simple and\ngives post-processing corrections that can be applied to any MB results.\nApplications to a model insulator (P$_2$ in a supercell), to semiconducting Si,\nand to metallic Na show that the method delivers greatly improved FS\ncorrections."
    },
    {
        "anchor": "Formation of Highly Tunable Periodic Plasmonic Structures on Gold Films\n  Using Direct Laser Writing: Direct laser writing method is a promising technique for the large-scale and\ncost-effective fabrication of periodic nanostructure arrays exciting hybrid\nlattice plasmons. This type of electromagnetic mode manifests a narrow and deep\nresonance peak with a high dispersion whose precise controllability is crucial\nfor practical applications in photonic devices. Here, the formation of\ndifferently shaped gold nanostructures using the direct laser writing method on\nAu layers of different thicknesses is presented. The resonance peak is\ndemonstrated to be highly dependent on the shape of the structures in the\narray, thus its position in the spectra, as well as the quality, can be\nadditionally modulated by changing the morphology. The shape of the structure\nand the resonance itself pertain not only on the laser pulse energy but also on\nthe grating period. This overlapping effect occurring at distances smaller than\nthe diameter of the focused laser beam is studied in detail. By taking\nadvantage of the highly controllable plasmonic resonance, the fabricated\ngratings open up new opportunities for applications in sensing.",
        "positive": "Saturated Low-Temperature Conductivity in Ultrafast Semiconductor\n  Nanocomposites: This article presents studies on low-field electrical conduction in the range\n4-to-300 K for a ultrafast material: InGaAs:ErAs grown by molecular beam\nepitaxy. The unique properties include nano-scale ErAs crystallines in host\nsemiconductor, a deep Fermi level, and picosecond ultrafast photocarrier\nrecombination. As the temperature drops, the conduction mechanisms are in the\nsequence of thermal activation, nearest-neighbor hopping, variable-range\nhopping, and Anderson localization. In the low-temperature limit,\nfinite-conductivity metallic behavior, not insulating, was observed. This\nunusual conduction behavior is explained with the Abrahams scaling theory."
    },
    {
        "anchor": "Colossal resistivity change besides magnetoresistance: an extended\n  theoretical framework for electronic transport of manganites: Current theoretical approaches to manganites mainly stem from magnetic\nframework, in which the electronic transport is thought to be spin-dependent\nand the double exchange mechanism plays a core role. However, quite a number of\nexperimental observations can yet not be reasonably explained. For example,\nmultiplicate insulator-metal transitions and resistivity reduction induced by\nperturbations other than magnetic field, such as electric current, are not well\nunderstood. A comprehensive analysis on earlier extensive studies is performed\nand two types of origins for resistivity change are highlighted. Besides the\ninsulated-to-metallic transition induced by external field such as magnetic\nfield, the insulated-to-insulated transition induced extrinsically is even a\nmore important source for the colossal resistivity change. We propose an\nextended framework for the electronic transport of manganites, in which the\ncontribution of charge degree of freedom is given a special priority.",
        "positive": "Morphological analysis of 3d atom probe data using Minkowski functionals: We present a morphological analysis of atom probe data of nanoscale\nmicrostructural features, using methods developed by the astrophysics community\nto describe the shape of superclusters of galaxies. We describe second-phase\nregions using Minkowski functionals, representing the regions' volume, surface\narea, mean curvature and Euler characteristic. The alloy data in this work show\nmicrostructures that can be described as sponge-like, filament-like,\nplate-like, and sphere-like at different concentration levels, and we find\nquantitative measurements of these features. To reduce user decision-making in\nconstructing isosurfaces and to enhance the accuracy of the analysis a maximum\nlikelihood based denoising filter was developed. We show that this filter\nperforms significantly better than a simple Gaussian smoothing filter. We also\ninterpolate the data using natural cubic splines, to refine voxel sizes and to\nrefine the surface. We demonstrate that it is possible to find a mathematically\nwell-defined, quantitative description of microstructure from atomistic\ndatasets, to sub-voxel resolution, without user-tuneable parameters."
    },
    {
        "anchor": "Ultrafast measurements of mode-specific deformation potentials of\n  Bi$_2$Te$_3$ and Bi$_2$Se$_3$: Quantifying electron-phonon interactions for the surface states of\ntopological materials can provide key insights into surface-state transport,\ntopological superconductivity, and potentially how to manipulate the surface\nstate using a structural degree of freedom. We perform time-resolved x-ray\ndiffraction (XRD) and angle-resolved photoemission (ARPES) measurements on\nBi$_2$Te$_3$ and Bi$_2$Se$_3$, following the excitation of coherent A$_{1g}$\noptical phonons. We extract and compare the deformation potentials coupling the\nsurface electronic states to local A$_{1g}$-like displacements in these two\nmaterials using the experimentally determined atomic displacements from XRD and\nelectron band shifts from ARPES.We find the coupling in Bi$_2$Te$_3$ and\nBi$_2$Se$_3$ to be similar and in general in agreement with expectations from\ndensity functional theory. We establish a methodology that quantifies the\nmode-specific electron-phonon coupling experimentally, allowing detailed\ncomparison to theory. Our results shed light on fundamental processes in\ntopological insulators involving electron-phonon coupling.",
        "positive": "Optical microcavity with semiconducting single-wall carbon nanotubes: We report studies of optical Fabry-Perot microcavities based on\nsemiconducting single-wall carbon nanotubes with a quality factor of 160. We\nexperimentally demonstrate a huge photoluminescence signal enhancement by a\nfactor of 30 in comparison with the identical film and by a factor of 180 if\ncompared with a thin film containing non-purified (8,7) nanotubes. Futhermore,\nthe spectral full-width at half-maximum of the photo-induced emission is\nreduced down to 8 nm with very good directivity at a wavelength of about 1.3\n$\\mu$m. Such results prove the great potential of carbon nanotubes for photonic\napplications."
    },
    {
        "anchor": "E-beam manipulation of Si atoms on graphene edges with\n  aberration-corrected STEM: The burgeoning field of atomic level material control holds great promise for\nfuture breakthroughs in quantum and memristive device manufacture and\nfundamental studies of atomic-scale chemistry. Realization of atom-by atom\ncontrol of matter represents a complex and ongoing challenge. Here, we explore\nthe feasibility of controllable motion of dopant Si atoms at the edges of\ngraphene via the sub-atomically focused electron beam in a scanning\ntransmission electron microscope (STEM). We demonstrate that the graphene edges\ncan be cleaned of Si atoms and then subsequently replenished from nearby source\nmaterial. It is also shown how Si edge atoms may be pushed from the edge of a\nsmall hole into the bulk of the graphene lattice and from the bulk of the\nlattice back to the edge. This is accomplished through sputtering of the edge\nof the graphene lattice to bury or uncover Si dopant atoms. These experiments\nform an initial step toward general atomic scale material control.",
        "positive": "Categorization of Next Generation Nanomaterials: International\n  Cooperation on the Categorization of Nanomaterials in the Regulatory Chemical\n  Context: Categorization approaches have been effectively applied to chemicals, and\nmany have tried to apply variations of these approaches to nanomaterials. Given\nthe added complexities of nanomaterials, this has been challenging.\nInternational cooperation on categorization approaches has been made, primarily\nthrough the Organization for Economic Cooperation and Development. Progress has\nbeen limited given the complexities of nanomaterials, especially given the need\nto consider not only the intrinsic properties of the materials but also\nproperties dependent on the system into which it is introduced. Consideration\nmust also be given to the different purposes and contexts, in particular\nregulatory contexts, to which the categorization schemes would be applied. More\nprogress can be anticipated by focusing on areas of overlap among countries\nsuch as physicochemical properties."
    },
    {
        "anchor": "Studies on the Structures and Physical Properties of Crystal Polymorphs\n  for Poly(Vinylidene Fluoride) Based on the Density Functional Theory: The structures and electronic states in all polymorphs of poly(vinylidene\nfluoride) (PVDF) were calculated in various levels using the CRYSTAL software.\nThe calculated lattice constants with PBE0/cc-pVTZ agreed well with\nexperimental values. The molecular structure of PVDF was clarified. Derived\nelectronic and phonon dispersions correspond closely with the experimental\nvalence X-ray photoelectron and infrared (IR)/Raman spectra, respectively. The\namount of spontaneous polarization in polar crystal forms was determined and\nthe effect of long-range Coulomb interactions were discussed. The calculation\nmethod used in this report was confirmed to be precise and shows promise for\nexamining ferroelectric polymers.",
        "positive": "Fundamental Fracture Mechanics Equation of Material: On the basis of energy conservation law an without utilizing Linear Fracture\nMechanics (LFM) postulates the equation of a real-structure material\nelastic-plastic fracture has been derived. With the help of this equation the\nforce and energy criteria of Non-linear Fracture Mechanics (NLFM) have been\nfound. These criteria constitute the basis of modern strength analysis of\nmachineparts and structures made of real-structure materials. $K_{lc}$\ndependence on ultimate strength limit, yield limit and impact toughness has\nbeen established and experimentally confirmed for a number of steels"
    },
    {
        "anchor": "Semimetal-antiferromagnetic insulator transition in graphene induced by\n  biaxial strain: We report first-principles calculations on antiferromagnetic spin ordering in\ngraphene under biaxial strain. Using hybrid functional calculations, we found\nthat semimetallic graphene sheets undergo a transition to antiferromagnetic\ninsulators at a biaxial strain of 7.7% and that the band gap rapidly increases\nafter the onset of this transition before reaching 0.9 eV at a biaxial strain\nof 12%. We examined the competition of the antiferromagnetic spin ordering with\ntwo-dimensional Peierls distortions upon biaxial strain, and found that the\npreceding antiferromagnetic insulator phase impedes the Peierls insulator\nphase. The antiferromagnetic insulator phase is destabilized upon carrier\nfilling but robust up to moderate carrier densities. This work indicates that\nbiaxially strained graphene represents a noble system where the\nelectron-electron and electron-lattice interactions compete with each other in\na simple but nontrivial way.",
        "positive": "Evidence of Spin Frustration in Vanadium Diselenide Monolayer Magnet: Monolayer VSe2, featuring both charge density wave and magnetism phenomena,\nrepresents a unique van der Waals magnet in the family of metallic\ntwo-dimensional transition-metal dichalcogenides (2D-TMDs). Herein, by means of\nin-situ microscopic and spectroscopic techniques, including scanning tunneling\nmicroscopy/spectroscopy, synchrotron X-ray and angle-resolved photoemission,\nand X-ray absorption, direct spectroscopic signatures are established, that\nidentify the metallic 1T-phase and vanadium 3d1 electronic configuration in\nmonolayer VSe2 grown on graphite by molecular-beam epitaxy. Element-specific\nX-ray magnetic circular dichroism, complemented with magnetic susceptibility\nmeasurements, further reveals monolayer VSe2 as a frustrated magnet, with its\nspins exhibiting subtle correlations, albeit in the absence of a long-range\nmagnetic order down to 2 K and up to a 7 T magnetic field. This observation is\nattributed to the relative stability of the ferromagnetic and antiferromagnetic\nground states, arising from its atomic-scale structural features, such as\nrotational disorders and edges. The results of this study extend the current\nunderstanding of metallic 2D-TMDs in the search for exotic low-dimensional\nquantum phenomena, and stimulate further theoretical and experimental studies\non van der Waals monolayer magnets."
    },
    {
        "anchor": "Nitrogen flow rate dependent atomic coordination, phonon vibration and\n  surface analysis of DC Magnetron sputtered Nitrogen rich-AlN thin films: In this work, the effect on crystallite orientation, surface morphology,\nfractal geometry, structural coordination and electronic environment of DC\nmagnetron sputtered AlN films were investigated. X-ray diffraction results\ndisclosed that the c-axis orientation of AlN films increased with the preferred\nwurtzite hexagonal structure above 17% N2 flow. X-ray reflectivity data\nconfirmed AlN film density increased with increasing N2 flow and was found to\nbe 3.18g/cm3 for 40% N2. The transition of electrons from N 1s to 2p states\nhybridized with Al 3p states because of {\\pi}* resonance was obtained from\nX-ray absorption spectroscopy of the N K-edge. The semi-empirical coordination\ngeometry of nitrogen atoms has been studied by deconvolution of N K-edge. The\nsurface composition of AlN films at 40% N2 consists of 32.08, 51.94 and\n15.97at.% Al, N and O respectively. Blue-shifting of A1(LO) and E1(LO) modes in\nthe Raman spectra at phonon energies 800 and 1051cm-1 respectively was most\nlikely due to the presence of oxygen bonds in the AlN films.",
        "positive": "Electronic structure and local distortions in epitaxial ScGaN films: High energy-resolution fluorescence-detected X-ray absorption spectroscopy\nand density functional theory calculations were used to investigate the local\nbonding and electronic structure of Sc in epitaxial wurtzite-structure\nSc$_{x}$Ga$_{1-x}$N films with x $\\le$ 0.059. Sc atoms are found to substitute\nfor Ga atoms, accompanied by a local distortion involving an increase in the\ninternal lattice parameter u around the Sc atoms. The local bonding and\nelectronic structure at Sc are not affected strongly by the strain state or the\ndefect microstructure of the films. These data are consistent with theoretical\npredictions regarding the electronic structure of dilute Sc$_{x}$Ga$_{1-x}$N\nalloys."
    },
    {
        "anchor": "Epitaxial Synthesis of Blue Phosphorene: Phosphorene is a new two-dimensional material composed of a single or few\natomic layers of black phosphorus. Phosphorene has both an intrinsic tunable\ndirect band gap and high carrier mobility values, which make it suitable for a\nlarge variety of optical and electronic devices. However, the synthesis of\nsingle-layer phosphorene is a major challenge. The standard procedure to obtain\nphosphorene is by exfoliation. More recently, the epitaxial growth of\nsingle-layer phosphorene on Au(111) has been investigated by molecular beam\nepitaxy and the obtained structure has been described as a blue-phosphorene\nsheet. In the present study, large areas of high-quality monolayer phosphorene,\nwith a band gap value at least equal to 0.8 eV, have been synthesized on\nAu(111). Our experimental investigations, coupled with DFT calculations, give\nevidence of two distinct phases of blue phosphorene on Au(111), instead of one\nas previously reported, and their atomic structures have been determined.",
        "positive": "Disconnection-mediated twin embryo growth in Mg: While deformation twinning in hexagonal close-packed metals has been widely\nstudied due to its substantial impact on mechanical properties, an\nunderstanding of the detailed atomic processes associated with twin embryo\ngrowth is still lacking. Conducting molecular dynamics simulations on Mg, we\nshow that the propagation of twinning disconnections emitted by basal-prismatic\ninterfaces controls the twin boundary motion and is the rate-limiting mechanism\nduring the initial growth of the twin embryo. The time needed for disconnection\npropagation is related to the distance between the twin tips, with widely\nspaced twin tips requiring more time for a unit twin boundary migration event\nto be completed. Thus, a phenomenological model, which unifies the two\nprocesses of disconnection and twin tip propagation, is proposed here to\nprovide a quantitative analysis of twin embryo growth. The model fits the\nsimulation data well, with two key parameters (twin tip velocity and twinning\ndisconnection velocity) being extracted. In addition, a linear relationship\nbetween the ratio of twinning disconnection velocity to twin tip velocity and\nthe applied shear stress is observed. Using an example of twin growth in a\nnanoscale single crystal from the recent literature, we find that our molecular\ndynamics simulations and analytical model are in good agreement with\nexperimental data."
    },
    {
        "anchor": "Calcium Carbonate Polyamorphism and Its Role in Biomineralization: How\n  Many Amorphous Calcium Carbonates Are There?: Although the polymorphism of calcium carbonate is well known, and its\npolymorphs-calcite, aragonite, and vaterite-have been highly studied in the\ncontext of biomineralization, polyamorphism is a much more recently discovered\nphenomenon, and the existence of more than one amorphous phase of calcium\ncarbonate in biominerals has only very recently been understood. Here we\nsummarize what is known about polyamorphism in calcium carbonate as well as\nwhat is under- stood about the role of amorphous calcium carbonate in\nbiominerals. We show that consideration of the amorphous forms of calcium\ncarbonate within the physical notion of polyamorphism leads to new insights\nwhen it comes to the mechanisms by which polymorphic structures can evolve in\nthe first place. This not only has implications for our understanding of\nbiomineralization, but also of the means by which crystallization may be\ncontrolled in medical, pharmaceutical, and industrial contexts.",
        "positive": "Metal-Organic Chemical Vapor Deposition of PtSe2: Platinum diselenide (PtSe2), a novel two-dimensional material from the class\nof noble-metal dichalcogenide (NMD), has recently received significant\nattention due to its outstanding properties. PtSe2, which undergoes a semi\nmetallic to semiconductor transition when thinned, offers a band-gap in the\ninfrared range and good air stability. These properties make it a prime active\nmaterial in optoelectronic and chemical sensing devices. However, a synthesis\nmethod that can produce large-scale and reliable high quality PtSe2 is highly\nsought after. Here, we present PtSe2 growth by metal organic chemical vapor\ndeposition. Films were grown on a variety of centimeter scale substrates and\nwere characterized by Raman, X-ray photoelectron and X-ray diffraction\nspectroscopy, as well as scanning tunneling microscopy and spectroscopy.\nDomains within the films are found to be up to several hundred nanometers in\nsize, and atomic scale measurements show their highly ordered crystalline\nstructure. The thickness of homogenous films can be controlled via the growth\ntime. This work provides fundamental guidance for the synthesis and\nimplementation of high quality, large-scale PtSe2 layers, hence offering the\nkey requirement for the implementation of PtSe2 in future electronic devices."
    },
    {
        "anchor": "Layering at liquid metal surfaces and interfaces: Friedel oscillations\n  and confinement effects: The structures of the liquid surface and the liquid-solid interface of sodium\nhave been characterized with extensive first-principles molecular dynamics\nsimulations. Friedel oscillations in the electronic charge density at the free\nsurface were found to persist across the solid-to-liquid melting transition,\nwith a small but distinctive electronic layering that remains decoupled from\nthe atomic positions. Strong ionic layering was observed both at the liquid\nsurface and at the liquid-solid interface, notwithstanding the absence of\nFriedel oscillations or under-coordinated atoms in the latter case. Confinement\neffects at these soft or hard boundaries drive the atoms into\nquasi-close-packed layers; even for this prototypical free-electron metal\nFriedel oscillations are not relevant to ordering.",
        "positive": "Interfacial two-dimensional oxide enhances photocatalytic activity of\n  graphene/titania via electronic structure modification: A two-dimensional layer of oxide reveals itself as a essential element to\ndrive the photocatalytic activity in a nanostructured hybrid material, which\ncombines high-quality epitaxial graphene and titanium dioxide nanoparticles. In\nparticular, it has been revealed that the addition of a 2D Ti oxide layer\nsandwiched between graphene and metal induces a p-doping of graphene and a\nconsistent shift in the Ti d states. These modifications induced by the\ninterfacial oxide layer induce a reduction of the probability of charge carrier\nrecombination and enhance the photocatalytic activity of the heterostructure.\nThis is indicative of a capital role played by thin oxide films in fine-tuning\nthe properties of heterostructures based on graphene and pave the way to new\ncombinations of graphene/oxides for photocatalysis-oriented applications."
    },
    {
        "anchor": "Magnetic Phase Control in Monolayer Films by Substrate Tuning: We propose to tailor exchange interactions in magnetic monolayer films by\ntuning the adjacent non-magnetic substrate. As an example, we demonstrate a\nferromagnetic-antiferromagnetic phase transition for one monolayer Fe on a\nTa(x)W(1-x)(001) surface as a function of the Ta concentration. At the critical\nTa concentration, the nearest-neighbor exchange interaction is small and the\nmagnetic phase space is dramatically broadened. Complex magnetic order such as\nspin-spirals, multiple-Q, or even disordered local moment states can occur,\noffering the possibility to store information in terms of ferromagnetic dots in\nan otherwise zero-magnetization state matrix.",
        "positive": "Structural simplicity and complexity of compressed calcium: electronic\n  origin: Simple cubic structure with one atom in the unit cell found in compressed\ncalcium is contrintuitive with regards to traditional view on tendency of\ntransition to densely packed structures on the increase of pressure. To\nunderstand this unusual transformation it is necessary to assume electron\ntransfer from outer core to the valence band and increase of valence electron\nnumber for calcium from 2 to ~3,5. This assumption is supported by the model of\nthe Fermi sphere - Brillouin zone interaction that increases under compression.\nRecently found structure of Ca-VII with tetragonal cell containing 32 atoms\n(tI32) is similar to the intermetallic compound In5Bi3 with 3,75 valence\nelectrons per atom. Structural relations are analyzed in regard to a\nresemblance of the electronic structure. Correlations of structure and physical\nproperties of Ca are discussed."
    },
    {
        "anchor": "Growth, microstructure, and failure of crazes in glassy polymers: We report on an extensive study of craze formation in glassy polymers.\nMolecular dynamics simulations of a coarse-grained bead-spring model were\nemployed to investigate the molecular level processes during craze nucleation,\nwidening, and breakdown for a wide range of temperature, polymer chain length\n$N$, entanglement length $N_e$ and strength of adhesive interactions between\npolymer chains. Craze widening proceeds via a fibril-drawing process at\nconstant drawing stress. The extension ratio is determined by the entanglement\nlength, and the characteristic length of stretched chain segments in the\npolymer craze is $N_e/3$. In the craze, tension is mostly carried by the\ncovalent backbone bonds, and the force distribution develops an exponential\ntail at large tensile forces. The failure mode of crazes changes from\ndisentanglement to scission for $N/N_e\\sim 10$, and breakdown through scission\nis governed by large stress fluctuations. The simulations also reveal\ninconsistencies with previous theoretical models of craze widening that were\nbased on continuum level hydrodynamics.",
        "positive": "Defect State Density and Orbital Localization in a-Si:H/c-Si\n  Heterojunction and the Role of H: In this paper, we explore the effect of H and its bonding configurations on\nthe defect state density and orbital localization of hydrogenated amorphous Si\n(a-Si:H)/crystalline Si (c-Si) heterostructures using density functional theory\n(DFT) studies of model interfaces between amorphous silicon (a- Si)/a-Si:H and\nc-Si. To model the atomic configuration of a-Si on c-Si, melting and quenching\nsimulations were performed using classical molecular dynamics (MD). Different\nhydrogen contents were inserted into the a-Si in different bonding\nconfigurations followed by DFT relaxation to create the stable structures of\na-Si:H representative of hydrogenated a-Si on crystalline Si surfaces. In\ncontrast to crystalline heterojunctions (where the interface density is a\nmaximum at the interface), we find that, in the most energetically stable\nconfigurations of H atoms, the defect state density is relatively low at the\ninterface and maximum at the middle of a-Si layer. Our structural analysis\nshows that in these configurations, H atoms do not necessarily bond to dangling\nbonds or to interface atoms. However, they are able to significantly change the\natomic structure of the heterostructure and consequently decrease the density\nof defect states and orbital localization at the a-Si layer and more\nsignificantly at the interface of a-Si/c-Si. The general form of the modeled\ndefect state distribution demonstrates the passivating role of a-Si:H on c-Si\nsubstrates."
    },
    {
        "anchor": "Temperature dependence of the electron spin g factor in GaAs: The temperature dependence of the electron spin $g$ factor in GaAs is\ninvestigated experimentally and theoretically. Experimentally, the $g$ factor\nwas measured using time-resolved Faraday rotation due to Larmor precession of\nelectron spins in the temperature range between 4.5 K and 190 K. The experiment\nshows an almost linear increase of the $g$ value with the temperature. This\nresult is in good agreement with other measurements based on photoluminescence\nquantum beats and time-resolved Kerr rotation up to room temperature. The\nexperimental data are described theoretically taking into account a diminishing\nfundamental energy gap in GaAs due to lattice thermal dilatation and\nnonparabolicity of the conduction band calculated using a five-level kp model.\nAt higher temperatures electrons populate higher Landau levels and the average\n$g$ factor is obtained from a summation over many levels. A very good\ndescription of the experimental data is obtained indicating that the observed\nincrease of the spin $g$ factor with the temperature is predominantly due to\nband's nonparabolicity.",
        "positive": "Fermi energy determination for advanced smearing techniques: Smearing techniques are widely used in first-principles calculations of\nmetallic and magnetic materials, where they improve the accuracy of Brillouin\nzone sampling and lessen the impact of level-crossing instabilities. Smearing\nintroduces a fictitious electronic temperature that smooths the discontinuities\nof the integrands; consequently, a corresponding fictitious entropic term\narises, and needs to be considered in the total free energy functional.\nAdvanced smearing techniques -- such as Methfessel-Paxton and cold smearing --\nhave been introduced to guarantee that the system's total free energy remains\nindependent of the smearing temperature at least up to the second order. In\ndoing so, they give rise to non-monotonic occupation functions (and, for\nMethfessel-Paxton, non-positive definite), which can result in the chemical\npotential not being uniquely defined. We explore this shortcoming in detail and\nintroduce a numerical protocol utilizing Newton's minimization method that is\nable to identify the desired Fermi energy. We validate the method by\ncalculating the Fermi energy of $\\sim$20,000 materials and comparing it with\nthe results of standard bisection approaches. In passing, we also highlight how\ntraditional approaches, based on Fermi-Dirac or Gaussian smearing, are actually\nequivalent for all practical purposes, provided the smearing width is\nappropriately renormalized by a factor $\\sim$2.565."
    },
    {
        "anchor": "Temperature Dependence of Angular Momentum Transport Across Interfaces: Angular momentum transport in magnetic multilayered structures plays a\ncentral role in spintronic physics and devices. The angular momentum currents\nor spin currents are carried by either quasi-particles such as electrons and\nmagnons, or by macroscopic order parameters such as local magnetization of\nferromagnets. Based on the generic interface exchange interaction, we develop a\nmicroscopic theory that describes interfacial spin conductance for various\ninterfaces among non-magnetic metals, ferromagnetic and antiferromagnetic\ninsulators. Spin conductance and its temperature dependence are obtained for\ndifferent spin batteries including spin pumping, temperature gradient and spin\nHall effect. As an application of our theory, we calculate the spin current in\na trilayer made of a ferromagnetic insulator, an antiferromagnetic insulator\nand a non-magnetic heavy metal. The calculated results on the temperature\ndependence of spin conductance quantitatively agree with the existing\nexperiments.",
        "positive": "Tuning electronic and optical properties of bismuth monolayers by\n  molecular adsorption: We perform first-principles calculations of electronic and dielectric\nproperties of bismuthene functionalized with small ligands using\nfirst-principle calculations. We show that all functionalized structures have\ntopological insulating (TI) behavior with a sizeable gap by calculating the\nZ$_2$ topological invariant. Furthermore the adsorption of all groups induce a\nquasi-planar structure to the initially pristine bismuthene structure. Finally\nwe show that the dielectric properties show a large anisotropy with two main in\nplane absorption peaks."
    },
    {
        "anchor": "Source Shot Noise Mitigation in Focused Ion Beam Microscopy by\n  Time-Resolved Measurement: Focused ion beam (FIB) microscopy suffers from source shot noise - random\nvariation in the number of incident ions in any fixed dwell time - along with\nrandom variation in the number of detected secondary electrons per incident\nion. This multiplicity of sources of randomness increases the variance of the\nmeasurements and thus worsens the trade-off between incident ion dose and image\naccuracy. Time-resolved sensing combined with maximum likelihood estimation\nfrom the resulting sets of measurements greatly reduces the effect of source\nshot noise. Through Fisher information analysis and Monte Carlo simulations,\nthe reduction in mean-squared error or reduction in required dose is shown to\nbe by a factor approximately equal to the secondary electron yield. Experiments\nwith a helium ion microscope (HIM) are consistent with the analyses and suggest\naccuracy improvement for a fixed source dose, or reduced source dose for a\ndesired imaging accuracy, by a factor of about 3.",
        "positive": "Graphenes flakes under controlled biaxial deformation: Thin membranes, such as monolayer graphene of monoatomic thickness, are bound\nto exhibit lateral buckling under uniaxial tensile loading that impairs its\nmechanical behaviour. In this work, we have developed an experimental device to\nsubject 2D materials to controlled equibiaxial strain on supported beams that\ncan be flexed up or down to subject the material to either compression or\ntension, respectively. Using strain gauges in tandem with Raman spectroscopy\nmeasurements, we monitor the G and 2D phonon properties of graphene under\nbiaxial strain and thus extract important information about the uptake of\nstress under these conditions. The experimental shift over strain for the G and\n2D Raman peaks were found to be in the range of 62.3 \\pm 5 cm^-1/%, and 148.2\n\\pm 6 cm^-1/%, respectively, for monolayer but also bilayer graphenes. The\ncorresponding Gruneisen parameters for the G and 2D peaks were found to be\nbetween 1.97 \\pm 0.15 and 2.86 \\pm 0.12, respectively. These values agree\nreasonable well with those obtained from small-strain bubble-type experiments.\nThe results presented are also backed up by classical and ab initio molecular\ndynamics simulations and excellent agreement of \\Gamma-E2g shifts with strains\nand the Gruneisen parameter was observed."
    },
    {
        "anchor": "Time-dependent fields and anisotropy dominated magnetic media: We use a single dipole approximation to analyze the behavior of\nanisotropy-dominated magnetic nanoparticles subjected to an external r.f.\nfield. We identify the steady state oscillations and analyze their stability.\nWe also analyze the case when the external r.f. field has a time-dependent\nfrequency which insures the most effective switching of the magnetization.",
        "positive": "NaCl-assisted CVD growth of wafer scale high quality trilayer MoS$_2$\n  and the role of concentration boundary layer: Direct growth of wafer scale high quality 2D layered materials (2DLMs) on\nSiO$_2$/Si substrate is still a challenge. The chemical vapor deposition (CVD)\ntechnique has played a significant role in achieving a large area continuous\nfilm of 2DLMs. CVD growth requires the optimization of many growth parameters\nsuch as temperature, amount of precursors, pressure, carrier gas flow and\ndistance between the reactants. However, the role of boundary layer of\nreactants concentration has not been explored yet. The amount of precursors\nwhich leads to the formation of reactants concentration boundary layer has a\nsignificant role in controlling the thickness of growing material. Here, we\nreport the role of concentration boundary layer to achieve wafer-scale MoS$_2$\nin NaCl-assisted CVD growth at low temperature. Control of boundary layer\nthickness has led to the synthesis monolayer, bilayer, trilayer, and bulk\nMoS$_2$ film and flakes in our single-zone CVD at atmospheric pressure. Most\nimportantly, we have synthesized 7 $\\times$ 2.5 cm$^2$ area continuous, high\nquality trilayer MoS$_2$ film with good repeatability. We believe that our\napproach may lead to synthesize other wafer-scale 2DLMs that will pave the way\nfor nano- and optoelectronics."
    },
    {
        "anchor": "Dependence of simulated radiation damage on crystal structure and atomic\n  misfit in metals: This study investigates radiation damage in three metals in the low\ntemperature and high radiant flux regime using molecular dynamics and a Frenkel\npair accumulation method to simulate up to $2.0$ displacements per atom. The\nmetals considered include Fe, equiatomic CrCoNi, and a fictitious metal with\nidentical bulk properties to the CrCoNi composed of a single atom type referred\nto as an A-atom. CrCoNi is found to sustain higher concentrations of\ndislocations than either the Fe or A-atom systems and more stacking faults than\nthe A-atom system. The results suggest that the concentration of vacancies and\ninterstitials are substantially higher for the CrCoNi than the A-atom system,\nperhaps reflecting that the recombination radius is smaller in CrCoNi due to\nthe roughened potential energy landscape. A model that partitions the major\ncontributions from defects to the stored energy is described, and serves to\nhighlight a general need for higher fidelity approaches to point defect\nidentification.",
        "positive": "Evidence for a Dirac nodal-line semimetal in SrAs$_{3}$: Dirac nodal-line semimetals with the linear bands crossing along a line or\nloop, represent a new topological state of matter. Here, by carrying out\nmagnetotransport measurements and performing first-principle calculations, we\ndemonstrate that such a state has been realized in high-quality single crystals\nof SrAs3. We obtain the nontrivial pi Berry phase by analysing the Shubnikov-de\nHaas quantum oscillations. We also observe a robust negative longitudinal\nmagnetoresistance induced by the chiral anomaly. Accompanying first-principles\ncalculations identify that a single hole pocket enclosing the loop nodes is\nresponsible for these observations."
    },
    {
        "anchor": "Nano-crystalline inclusions as a low-pass filter for thermal transport\n  in a-Si: We use atomistic simulations to study the resonant acoustic modes and compare\ndifferent calculations of the acoustic mean-free path in amorphous systems with\nnanometric crystalline spherical inclusions. We show that the resonant acoustic\nproperties are not a simple combination of the vibrations in the inclusions and\nin the amorphous matrix. The presence of the inclusion affects the transport\nproperties mainly in the frequency range separating simple scattering from\nmultiple scattering processes. However, propagation of acoustic wavepackets is\nspatially heterogeneous and shows that the amorphous/crystalline interface acts\nas a low energy pass filter slowing down the high kinetic energy motion\nwhatever the vibration frequency. These heterogeneities cannot be catched by\nthe mean free path, but still they must play an important role in thermal\ntransport, thus raising the question of the correct modeling of thermal\ntransport in composite systems.",
        "positive": "Extended transfer matrix method for electron transmission in anisotropic\n  2D materials: Interplay of strain and (a)periodicity of potentials: We extend the conventional transfer matrix method to include anisotropic\nfeatures for electron transmission in two-dimensional materials, such as\nbreaking reflection law in pseudo-spin phases and wave vectors. This method\nallows to study transmission properties of anisotropic and stratified\nelectrostatic potential media from a wide range of tunable parameters, which\ninclude strain tensor and gating. We apply the extended matrix method to obtain\nthe electron transmission, conductance, and Fano factor for the interplay of an\nuniaxially strained graphene sheet with external one-dimensional aperiodic\npotentials. Our results suggest the possibility of visualizing this interplay\nfrom conductance measurements."
    },
    {
        "anchor": "Frustration of square cupola in Sr(TiO)Cu$_{4}$(PO$_{4}$)$_{4}$: The structural and magnetic properties of the square-cupola antiferromagnet\nSr(TiO)Cu$_{4}$(PO$_{4}$)$_{4}$ are investigated via x-ray diffraction,\nmagnetization, heat capacity, and $^{31}$P nuclear magnetic resonance\nexperiments on polycrystalline samples, as well as density-functional\nband-structure calculations. The temperature-dependent unit cell volume could\nbe described well using the Debye approximation with the Debye temperature of\n$\\theta_{\\rm D} \\simeq $ 550~K. Magnetic response reveals a pronounced\ntwo-dimensionality with a magnetic long-range-order below $T_{\\rm N} \\simeq\n6.2$~K. High-field magnetization exhibits a kink at $1/3$ of the saturation\nmagnetization. Asymmetric $^{31}$P NMR spectra clearly suggest strong in-plane\nanisotropy in the magnetic susceptibility, as anticipated from the crystal\nstructure. From the $^{31}$P NMR shift vs bulk susceptibility plot, the\nisotropic and axial parts of the hyperfine coupling between $^{31}$P nuclei and\nthe Cu$^{2+}$ spins are calculated to be $A_{\\rm hf}^{\\rm iso} \\simeq 6539$ and\n$A_{\\rm hf}^{\\rm ax} \\simeq 952$~Oe/$\\mu_{\\rm B}$, respectively. The\nlow-temperature and low-field $^{31}$P NMR spectra indicate a commensurate\nantiferromagnetic ordering. Frustrated nature of the compound is inferred from\nthe temperature-dependent $^{31}$P NMR spin-lattice relaxation rate and\nconfirmed by our microscopic analysis that reveals strong frustration of the\nsquare cupola by next-nearest-neighbor exchange couplings.",
        "positive": "Resolving the wave-vector in negative refractive media: The sign of\n  $\\sqrt{Z}$: We address the general issue of resolving the wave-vector in complex\nelectromagnetic media including negative refractive media. This requires us to\nmake a physical choice for the sign of a square-root imposed merely by\nconditions of causality. By considering the analytic behaviour of the\nwave-vector in the complex plane, it is shown that there are a total of eight\nphysically distinct cases in the four quadrants of two Riemann sheets."
    },
    {
        "anchor": "Crystal and local atomic structure of Co-doped MgFeBO_4 warwickites: Single crystalline MgFeBO_4, Mg_0.5Co_0.5FeBO_4 and CoFeBO_4 have been grown\nby the flux method. The samples have been characterized by X-ray spectral\nanalysis, X-ray diffraction and X-ray absorption spectroscopy. The X-ray\nabsorption near-edge structure (XANES) and extended X-ray absorption fine\nstructure (EXAFS) spectra have been measured at the Fe andCoK-edges over a wide\ntemperature range (6.5 - 300 K). The composition, the charge state and local\nenvironment of both Fe and Co atoms have been determined. The effects of Mg\nsubstitution by Co on the local structural distortions have been revealed\nexperimentally and the M-O bond anisotropy has been found.",
        "positive": "Theory, preparation, properties and catalysis application in 2D\n  Graphynes-Based Materials: Carbon has three hybridization forms of sp-, sp2- and sp3-, and the\ncombination of different forms can obtain different kinds of carbon allotropes,\nsuch as diamond, carbon nanotubes, fullerene, graphynes (GYs) and graphdiyne\n(GDY). Among them, the GDY molecule is a single-layer two-dimensional (2D)\nplanar structure material with highly -conjugation formed by sp- and sp2-\nhybridization. GDY has a carbon atom ring composed of benzene ring and\nacetylene, which makes GDY have a uniformly distributed pore structure. In\naddition, GDY planar material have some slight wrinkles, which makes GDY have\nbetter self-stability than other 2D planar materials. The excellent properties\nof GDY make it attract the attention of researcher. Therefore, GDY is widely\nused in chemical catalysis, electronics, communications, clean energy and\ncomposite materials. This paper summarizes the recent progress of GDY research,\nincluding structure, preparation, properties and application of GDY in the\nfield of catalysts."
    },
    {
        "anchor": "Model Hessian for accelerating first-principles structure optimizations: We present two methods to accelerate first-principles structural relaxations,\nboth based on the dynamical matrix obtained from a universal model of springs\nfor bond stretching and bending. Despite its simplicity, the normal modes of\nthis model Hessian represent excellent internal coordinates for molecules and\nsolids irrespective of coordination, capturing not only the long-wavelength\nacoustic modes of large systems, but also the short-wavelength low-frequency\nmodes that appear in complex systems. In the first method, the model Hessian is\nused to precondition a conjugate gradients minimization, thereby drastically\nreducing the effective spectral width and thus obtaining a substantial\nimprovement of convergence. The same Hessian is used in the second method as a\nstarting point of a quasi-Newton algorithm (Broyden's method and modifications\nthereof), reducing the number of steps needed to find the correct Hessian.\nResults for both methods are presented for geometry optimizations of clusters,\nslabs, and biomolecules, with speed-up factors between 2 and 8.",
        "positive": "Nonlinear evolution of surface morphology in InAs/AlAs superlattices via\n  surface diffusion: Continuum simulations of self-organized lateral compositional modulation\ngrowth in InAs/AlAs short-period superlattices on InP substrate are presented.\nResults of the simulations correspond quantitatively to the results of\nsynchrotron x-ray diffraction experiments. The time evolution of the\ncompositional modulation during epitaxial growth can be explained only\nincluding a nonlinear dependence of the elastic energy of the growing epitaxial\nlayer on its thickness. From the fit of the experimental data to the growth\nsimulations we have determined the parameters of this nonlinear dependence. It\nwas found that the modulation amplitude don't depend on the values of the\nsurface diffusion constants of particular elements."
    },
    {
        "anchor": "Enhancing the Figure of Merit in Te-doped FeSb2 through nanostructuring: We study the thermoelectric properties of Te-doped FeSb2 nanostructured\nsamples. Four samples of stoichiometry FeSb1.84Te0.16 were prepared by a hot\npress method at temperatures of 200, 400, 500, and 600 oC. Te-doping enhances\nthe dimensionless figure of merit (ZT) on FeSb2 via two mechanisms. First, a\nsemiconductor to metal transition is induced, which enhances the value of the\npower factor at low-temperatures. Second, the thermal conductivity, which was\nalready reduced in nanostructured FeSb2 samples, is further reduced by\nincreased point defect scattering through the n type substitution of Sb site by\nTe atom. The combined effect results in a ZT = 0.022 at 100 K, an increase of\n62% over the ZT value for the optimized Te-doped single crystal sample. Hall\ncoefficient and electrical resistivity measurements reveal a decreased mobility\nand increased concentration of the carriers in the doped sample.",
        "positive": "A High Throughput Study of both Compositionally Graded and Homogeneous\n  Fe-Pt Thin Films: Compositionally graded Fe-Pt thin films were prepared on stationary 100 mm Si\nsubstrates by magnetron sputtering a base target of Fe on which a piece of Pt\nis asymmetrically positioned. Energy Dispersive X-Ray analysis was used to map\nthe variation in film composition across the substrate, as a function of the\nsize of the Pt piece. A scanning polar Magneto-Optical-Kerr-Effect system was\nused to probe the influence of composition and post-deposition annealing\nconditions (temperature and time) on coercivity. In this way the maximum\ncoercivity achievable for the sputtering system used could be established in a\nhigh throughput fashion. The evolution in coercivity with composition was\ncorrelated with the formation of L10 FePt and changes in its lattice\nparameters, as determined by scanning X-ray diffraction. High throughput\ncoercivity mapping was then carried out on homogeneous Fe-Pt thin films of\ndifferent composition treated to different annealing conditions. This study\nserves as a step towards the integration of coercive FePt films into\ncollectively fabricated devices."
    },
    {
        "anchor": "Low-Temperature Thermoelectric Performance and Optoelectronic Properties\n  of Monolayer of WX2N4(X = Si, Ge): We investigated the thermoelectric properties of the 2D monolayer of WX2N4\nusing Density Functional Theory combined with Boltzmann Transport Equation. We\nobtained an outstanding thermoelectric figure of merit of 0.91 at 400K for\np-type WGe2N4, whether it showed a ZT value of 0.56 for n-type at the same\ntemperature. On the other hand, the WSi2N4 showed significantly low ZT at room\ntemperature.",
        "positive": "Processing of dense bio-inspired ceramics with deliberate microtexture: The architectures of biological hard materials reveal finely tailored complex\nassemblies of mineral crystals. Numerous recent studies associate the design of\nthese local assemblies with impressive macroscopic response. Reproducing such\nexquisite control in technical ceramics conflicts with commonly used processing\nmethods. Here, we circumvent this issue by combining the recently developed\nMagnetically-Assisted Slip Casting (MASC) technique with the well-established\nprocess of Templated Grain Growth (TGG). MASC enables the local control over\nthe orientation of platelets dispersed among smaller isotropic particles. After\na high temperature pressure-less treatment, the grains of the final ceramic\nfollow the same orientation of the initial platelets. This combination allows\nus to produce 95 % dense alumina part with a grain orientation following any\ndeliberate orientation. We successfully fabricated microstructures inspired\nfrom biological materials with ceramics that present periodically varying\npatterns with a programmable pitch of a few tens of microns. We confirmed the\ncapacity of the process to tailor local mechanical properties through local\ngrains orientation using micro-indentation. This micrometer scale control over\nthe local mechanical properties could be applied to adapt ceramic structures to\ncomplex loads using this inexpensive and scalable process. In systems where\nfunctional properties also depend on anisotropic grain orientation, the\nprinciple presented here could enable the creation of new multifunctional\nceramics."
    },
    {
        "anchor": "Emergent zero-field anomalous Hall effect in a\n  reconstructedrutileantiferromagnetic metal: Anomalous Hall effect (AHE) emerged in antiferromagnetic metals shows\nintriguing physics and application potential. In contrast to certain\nnoncollinear antiferromagnets, rutile RuO$_2$ has been proposed recently to\nexhibit a crystal-assisted AHE with collinear antiferromagnetism. However, in\nRuO$_2$, the on-site magnetic moment accompanying itinerant 4d electrons is\nquite small, and more importantly, the AHE at zero external field is prohibited\nby symmetry because of the high-symmetry [001] direction of the N\\'eel vector.\nHere, we show the AHE at zero field in the collinear antiferromagnet, Cr-doped\nRuO$_2$. The appropriate doping of Cr at Ru sites results in a rotation of the\nN\\'eel vector from [001] to [110] and enhancement of the on-site magnetic\nmoment by one order of magnitude while maintaining a metallic state with the\ncollinear antiferromagnetism. The AHE with vanishing net moment in the\nRu$_{0.8}$Cr$_{0.2}$O$_2$ exhibits an orientation dependence consistent with\nthe [110]-oriented N\\'eel vector. These results open a new avenue to manipulate\nAHE in antiferromagnetic metals.",
        "positive": "Highly efficient nonvolatile magnetization switching and multi-level\n  states by current in single van der Waals topological ferromagnet Fe3GeTe2: Robust multi-level spin memory with the ability to write information\nelectrically is a long-sought capability in spintronics, with great promise for\napplications. Here we achieve nonvolatile and highly energy-efficient\nmagnetization switching in a single-material device formed of van-der-Waals\ntopological ferromagnet Fe3GeTe2, whose magnetic information can be readily\ncontrolled by a tiny current. Furthermore, the switching current density and\npower dissipation are about 400 and 4000 times smaller than those of the\nexisting spin-orbit-torque magnetic random access memory based on conventional\nmagnet/heavy-metal systems. Most importantly, we also demonstrate multi-level\nstates, switched by electrical current, which can dramatically enhance the\ninformation capacity density and reduce computing costs. Thus, our observations\ncombine both high energy efficiency and large information capacity density in\none device, showcasing the potential applications of the emerging field of\nvan-der-Waals magnets in the field of spin memory and spintronics."
    },
    {
        "anchor": "Electron-induced non-monotonic pressure dependence of the lattice\n  thermal conductivity of \u03b8-TaN: Recent theoretical and experimental research suggests that $\\theta$-TaN is a\nsemimetal with high thermal conductivity ($\\kappa$), primarily due to the\ncontribution of phonons ($\\kappa_\\texttt{ph}$). By using first-principles\ncalculations, we show a non-monotonic pressure dependence of the $\\kappa$ of\n$\\theta$-TaN. $\\kappa_\\texttt{ph}$ first increases until it reaches a maximum\nat around 60~GPa, and then decreases. This anomalous behaviour is a consequence\nof the competing pressure responses of phonon-phonon and phonon-electron\ninteractions, in contrast to the known materials BAs and BP, where the\nnon-monotonic pressure dependence is caused by the interplay between different\nphonon-phonon scattering channels. Although TaN has phonon dispersion features\nsimilar to BAs at ambient pressure, its response to pressure is different and\nan overall stiffening of the phonon branches takes place. Consequently, the\nrelevant phonon-phonon scattering weakens as pressure increases. However, the\nincreased electronic density of states near the Fermi level, and specifically\nthe emergence of additional pockets of the Fermi surface at the high-symmetry L\npoint in the Brillouin zone, leads to a substantial increase in phonon-electron\nscattering at high pressures, driving a decrease in $\\kappa_{\\mathrm{ph}}$. At\nintermediate pressures ($\\sim$~20$-$70~GPa), the $\\kappa$ of TaN surpasses that\nof BAs. Our work provides deeper insight into phonon transport in semimetals\nand metals where phonon-electron scattering is relevant.",
        "positive": "Direct visualization of the charge transfer in\n  Graphene/$\u03b1$-RuCl$_3$ heterostructure: We investigate the electronic properties of a graphene and $\\alpha$-ruthenium\ntrichloride (hereafter RuCl$_3$) heterostructure, using a combination of\nexperimental and theoretical techniques. RuCl$_3$ is a Mott insulator and a\nKitaev material, and its combination with graphene has gained increasing\nattention due to its potential applicability in novel electronic and\noptoelectronic devices. By using a combination of spatially resolved\nphotoemission spectroscopy, low energy electron microscopy, and density\nfunctional theory (DFT) calculations we are able to provide a first direct\nvisualization of the massive charge transfer from graphene to RuCl$_3$, which\ncan modify the electronic properties of both materials, leading to novel\nelectronic phenomena at their interface. The electronic band structure is\ncompared to DFT calculations that confirm the occurrence of a Mott transition\nfor RuCl$_3$. Finally, a measurement of spatially resolved work function allows\nfor a direct estimate of the interface dipole between graphene and RuCl$_3$.\nThe strong coupling between graphene and RuCl$_3$ could lead to new ways of\nmanipulating electronic properties of two-dimensional lateral heterojunction.\nUnderstanding the electronic properties of this structure is pivotal for\ndesigning next generation low-power opto-electronics devices."
    },
    {
        "anchor": "Enhanced Born Charge and Proximity to Ferroelectricity in Thallium\n  Halides: Electronic structure and lattice dynamics calculations on thallium halides\nshow that the Born effective charges in these compounds are more than twice\nlarger than the nominal ionic charges. This is a result of cross-band-gap\nhybridization between Tl-p and halogen-p states. The large Born charges cause\ngiant splitting between longitudinal and transverse optic phonon modes,\nbringing the lattice close to ferroelectric instability. Our calculations\nindeed show spontaneous lattice polarization upon lattice expansion starting at\n2%. It is remarkable that the apparently ionic thallium halides with a simple\ncubic CsCl structure and large differences in electronegativity between cations\nand anions can be very close to ferroelectricity. This can lead to effective\nscreening of defects and impurities that would otherwise be strong carrier\ntraps and may therefore contribute to the relatively good carrier transport\nproperties in TlBr radiation detectors.",
        "positive": "Synaptic Learning and Memory Functions Achieved in Self-rectifying BFO\n  Memristor under Extreme Environmental Temperature: Memristors have been intensively studied in recent years as promising\nbuilding blocks for next-generation non-volatile memory, artificial neural\nnetworks and brain-inspired computing systems. Even though the environment\nadaptability of memristor has been required in many application fields, it has\nbeen rarely reported due to the underlying mechanism could become invalid\nespecially at an elevated temperature. Here, we focus on achieving synaptic\nlearning and memory functions in BiFeO3 memristor in a wide range of\ntemperature. We have proved the ferroelectricity of BFO films at a record-high\ntemperature of 500 {\\deg}C by piezoresponse force microscopy (PFM) measurement.\nDue to the robust ferroelectricity of BFO thin film, an analog-like resistance\nswitching behavior has been clearly found in a wide range of temperature, which\nis attributed to the reversal of ferroelectric polarization. Various synaptic\nfunctions including long-term potentiation (LTP), depression (LTD), consecutive\npotentiation/depression (P/D) and spike-timing dependent plasticity (STDP) have\nbeen realized from -170 to 300 {\\deg}C, illustrating their potential for\nelectronic applications even under extreme environmental temperature."
    },
    {
        "anchor": "Self-organization and magnetic domain microstructure of Fe nanowire\n  arrays: Starting from essentially flat nanometer-thick Fe films, epitaxially grown at\nroom temperature on W(110) surfaces, we used carefully tuned annealing\nschedules to produce periodic arrays of nanoscale ferromagnetic wires. The\nstructural transition from continuous films to nanowire arrays is accompanied\nwith an in-plane 90 degree rotation of the spontaneous magnetization. Using\nspin-polarized low-energy electron microscopy to map the local magnetization\ndirections while annealing, we studied the role of the dewetting mechanism on\nthe self-organization and magnetization reorientation processes.",
        "positive": "Degree of order dependence on magnetocrystalline anisotropy in bct FeCo\n  alloys: We investigate the magnetocrystalline anisotropy (MCA) energy of tetragonal\ndistorted FeCo alloys depending on the degree of order by first-principles\nelectronic structure calculation combined with the coherent potential\napproximation. The obtained results indicate that the MCA energy of FeCo alloys\nstrongly depends on the degree of order under optimal conditions, where the\naxial ratio of the bct structure is 1.25 and the composition is Fe0.5Co0.5. We\nfind that the modification of the electronic structure resulting from electron\nscattering by chemical disorder has a considerable influence on the MCA under\nthese conditions."
    },
    {
        "anchor": "Dynamics of stick-slip in peeling of an adhesive tape: We investigate the dynamics of peeling of an adhesive tape subjected to a\nconstant pull speed. We derive the equations of motion for the angular speed of\nthe roller tape, the peel angle and the pull force used in earlier\ninvestigations using a Lagrangian. Due to the constraint between the pull\nforce, peel angle and the peel force, it falls into the category of\ndifferential-algebraic equations requiring an appropriate algorithm for its\nnumerical solution. Using such a scheme, we show that stick-slip jumps emerge\nin a purely dynamical manner. Our detailed numerical study shows that these set\nof equations exhibit rich dynamics hitherto not reported. In particular, our\nanalysis shows that inertia has considerable influence on the nature of the\ndynamics. Following studies in the Portevin-Le Chatelier effect, we suggest a\nphenomenological peel force function which includes the influence of the pull\nspeed. This reproduces the decreasing nature of the rupture force with the pull\nspeed observed in experiments. This rich dynamics is made transparent by using\na set of approximations valid in different regimes of the parameter space. The\napproximate solutions capture major features of the exact numerical solutions\nand also produce reasonably accurate values for the various quantities of\ninterest.",
        "positive": "Modeling of microwave-assisted switching in micron-sized magnetic\n  ellipsoids: The microwave assisted magnetisation reversal is modelled in a permalloy\nmicron-sized magnetic ellipsoid. Our simulations confirm that this process\nrequires less field than magnetisation reversal under a static field. This is\ndue to a different reversal mode which in case of the microwave-assisted\nprocess is always a ripple structure. During the magnetisation reversal two\nstages: nucleation and relaxation are distinguished. The nucleation process is\ngoverned by spinwave instabilities. The relaxation process is related to the\ndomain expansion through domain wall propagation determined by the precessional\nmotion of magnetic moments in the center of the domain walls. As a consequence,\nthe switching time is a complex oscillating function of the microwave\nfrequency."
    },
    {
        "anchor": "Experimental Evidence of Stable 2$H$ Phase on the Surface of Layered\n  1$T'$-TaTe$_2$: We report on the low-energy electronic structure of Tantalum ditelluride\n(1$T'$-TaTe$_2$), one of the charge density wave (CDW) materials from the group\nV transition metal dichalcogenides using angle-resolved photoemission\nspectroscopy (ARPES) and density functional theory (DFT). We find that the\nFermi surface topology of TaTe$_2$ is quite complicated compared to its\nisovalent compounds such as TaS$_2$, TaSe$_2$, and isostructural compound\nNbTe$_2$. More importantly, we discover that the surface electronic structure\nof 1$T'$-TaTe$_2$ has more resemblance to the 2$H$-TaTe$_2$, while the bulk\nelectronic structure has more resemblance to the hypothetical 1$T$-TaTe$_2$.\nThese experimental observations are thoroughly compared with our DFT\ncalculations performed on 1$T$-, 2$H$- and 2$H$ (monolayer)/1$T$- TaTe$_2$. We\nfurther notice that the Fermi surface topology is temperature independent up to\n180 K, confirming that the 2$H$ phase on the surface is stable up to 180 K and\nthe CDW order is not due to the Fermi surface nesting.",
        "positive": "Single Photon Emission from Plasma Treated 2D Hexagonal Boron Nitride: Artificial atomic systems in solids are becoming increasingly important\nbuilding blocks in quantum information processing and scalable quantum\nnanophotonic networks. Yet, synthesis of color centers that act as single\nphoton emitters which are suitable for on-chip applications is still beyond\nreach. Here, we report a number of plasma and thermal annealing methods for the\nfabrication of emitters in tape-exfoliated hexagonal boron nitride (hBN)\ncrystals. A two-step process comprised of Ar plasma etching and subsequent\nannealing in Ar is highly robust, and yields a seven-fold increase in the\nconcentration of emitters in hBN. The initial plasma etching step generates\nemitters that suffer from blinking and bleaching, whereas the two-step process\nyields emitters that are photostable at room temperature and have an emission\nenergy distribution that is red-shifted relative to that of pristine hBN. An\nanalysis of emitters fabricated by a range of plasma and annealing treatments,\ncombined with a theoretical investigation of point defects in hBN indicates\nthat single photon emitters characterized by a high degree of photostability\nand emission wavelengths greater than ~700 nm are associated with defect\ncomplexes that contain oxygen. This is further confirmed by generating the\nemitters by annealing hBN in an oxidative atmosphere. Our findings advance\npresent understanding of the structure of quantum emitter in hBN and enhance\nthe nanofabrication toolkit that is needed to realize integrated quantum\nnanophotonics based on 2D materials."
    },
    {
        "anchor": "Crystallization of Lennard-Jones nanodroplets: from near melting to\n  deeply supercooled: We carry out molecular dynamics (MD) and Monte Carlo (MC) simulations to\ncharacterize nucleation in liquid clusters of 600 Lennard-Jones particles over\na broad range of temperatures. We use the formalism of mean first-passage times\nto determine the rate and find that Classical Nucleation Theory (CNT) predicts\nthe rate quite well, even when employing simple modelling of crystallite shape,\nchemical potential, surface tension and particle attachment rate, down to the\ntemperature where the droplet loses metastability and crystallization proceeds\nthrough growth-limited nucleation in an unequilibrated liquid. Below this\ncrossover temperature, the nucleation rate is still predicted when MC\nsimulations are used to directly calculate quantities required by CNT.\nDiscrepancy in critical embryo sizes obtained from MD and MC arises when\ntwinned structures with five-fold symmetry provide a competing free energy\npathway out of the critical region. We find that crystallization begins with\nhcp-fcc stacked precritical nuclei and differentiation to various end\nstructures occurs when these embryos become critical. We confirm that using the\nlargest embryo in the system as a reaction coordinate is useful in determining\nthe onset of growth-limited nucleation and show that it gives the same free\nenergy barriers as the full cluster size distribution once the proper reference\nstate is identified. We find that the bulk melting temperature controls the\nrate, even though the solid-liquid coexistence temperature for the droplet is\nsignificantly lower. The value of surface tension that renders close agreement\nbetween CNT and direct rate determination is significantly lower than what is\nexpected for the bulk system.",
        "positive": "Mexican Hat and Rashba Bands in Few-Layer van der Waals Materials: The valence band of a variety of few-layer, two-dimensional materials\nconsists of a ring of states in the Brillouin zone. The energy-momentum\nrelation has the form of a `Mexican hat' or a Rashba dispersion. The\ntwo-dimensional density of states is singular at or near the band edge, and the\nband-edge density of modes turns on nearly abruptly as a step function. The\nlarge band-edge density of modes enhances the Seebeck coefficient, the power\nfactor, and the thermoelectric figure of merit ZT. Electronic and\nthermoelectric properties are determined from ab initio calculations for\nfew-layer III-VI materials GaS, GaSe, InS, InSe, for Bi$_{2}$Se$_{3}$, for\nmonolayer Bi, and for bilayer graphene as a function of vertical field. The\neffect of interlayer coupling on these properties in few-layer III-VI materials\nand Bi$_{2}$Se$_{3}$ is described. Analytical models provide insight into the\nlayer dependent trends that are relatively consistent for all of these\nfew-layer materials. Vertically biased bilayer graphene could serve as an\nexperimental test-bed for measuring these effects."
    },
    {
        "anchor": "Pursuit of thermoelectric properties in a novel Half Heusler compound:\n  HfPtPb: We explore the structural, electronic, mechanical and thermoelectric\nproperties of a new half Heusler compound, HfPtPb which is all metallic heavy\nelement and has been recently been proposed to be stable [Nature Chem 7 (2015)\n308]. In the present work, we employ density functional theory and\nsemiclassical Boltzmann transport equations with constant relaxation time\napproximation. The mechanical properties such as Shear modulus, Young modulus,\nelastic constants, Poisson ratio, and shear anisotropy factor are investigated.\nThe elastic and phonon properties reveal that this compound is mechanically and\ndynamically stable. Pugh and Frantsevich ratio demonstrates the ductile\nbehavior and Shear anisotropic factor reflects the anisotropic nature of\nHfPtPb. The calculation of band structure predicts that this compound is\nsemiconductor in nature with band gap 0.86 eV. The thermoelectric transport\nparameters such as Seebeck coefficient, electrical conductivity, and electronic\nthermal conductivity and lattice thermal conductivity have been calculated as a\nfunction of temperature. The highest value of Seebeck coefficient is obtained\nfor n-type doping at optimal carrier concentration. We predict the maximum\nvalue of the figure of merit 0.25 at 1000 K. Our investigation suggests that\nthis material is n-type semiconductor.",
        "positive": "An Index Theorem for Graphene: We consider a graphene sheet folded in an arbitrary geometry, compact or with\nnanotube-like open boundaries. In the continuous limit, the Hamiltonian takes\nthe form of the Dirac operator, which provides a good description of the low\nenergy spectrum of the lattice system. We derive an index theorem that relates\nthe zero energy modes of the graphene sheet with the topology of the lattice.\nThe result coincides with analytical and numerical studies for the known cases\nof fullerene molecules and carbon nanotubes and it extend to more complicated\nmolecules. Potential applications to topological quantum computation are\ndiscussed."
    },
    {
        "anchor": "Precise microwave characterization of MgO substrates for HTS circuits\n  with superconducting post dielectric resonator: Accurate data of complex permittivity of dielectric substrates are needed for\nefficient design of HTS microwave planar circuits. We have tested MgO\nsubstrates from three different manufacturing batches using a dielectric\nresonator with superconducting parts recently developed for precise microwave\ncharacterization of laminar dielectrics at cryogenic temperatures. The\nmeasurement fixture has been fabricated using a SrLaAlO3 post dielectric\nresonator with DyBa2Cu3O7 end plates and silver-plated copper sidewalls to\nachieve the resolution of loss tangent measurements of 2 {\\times} 10-6. The\ntested MgO substrates exhibited the average relative permittivity of 9.63 and\ntan {\\delta} from 3.7 {\\times} 10-7 to 2 {\\times} 10-5 at frequency of 10.5 GHz\nin the temperature range from 14 to 80 K.",
        "positive": "Implications of Shock Wave Experiments with Precompressed Materials for\n  Giant Planet Interiors: This work uses density functional molecular dynamics simulations of fluid\nhelium at high pressure to examine how shock wave experiments with\nprecompressed samples can help characterizing the interior of giant planets. In\nparticular, we analyze how large of a precompression is needed to probe a\ncertain depth in a planet's gas envelope. We find that precompressions of up to\n0.1, 1.0, 10, or 100 GPa are needed to characterized 2.5, 5.9, 18, to 63% of\nJupiter's envelope by mass."
    },
    {
        "anchor": "Identification of the Chromophores in Prussian blue: Prussian blue was the world's first synthetic dye. Its structural, optical\nand magnetic properties have led to many applications in technology and\nmedicine, and provide paradigms for understanding coordination polymers,\nframework materials and mixed-valence compounds. The intense red absorption of\nPrussian blue that characterises chemical and physical properties critical to\nmany of these applications is now shown to arise from localised intervalence\ncharge transfer transitions within two chromophoric variants (ligand isomers)\nof an idealised \"dimer\" fragment {(NC)5FeII}(mu-CN){FeIII(NC)3(H2O)2}. This\nfragment is only available in modern interpretations of the material's crystal\nstructure, with the traditional motif {(NC)5FeII}(mu-CN){FeIII(NC)5} shown not\nto facilitate visible absorption. Essential to the analysis is the\ndemonstration, obtained independently using absorption and magnetic circular\ndichroism spectroscopies, that spectra of Prussian blues are strongly\ninfluenced by particle size and (subsequent) light scattering. These\ninterpretations are guided and supported by density functional theory\ncalculations (CAM-B3LYP), supplemented by coupled cluster and Bethe-Salpeter\nspectral simulations, as well as electron paramagnetic resonance spectroscopy\nof Prussian blue and a model molecular dimeric ion [Fe2(CN)11]6-.",
        "positive": "Interlayer ferroelectric polarization modulated anomalous Hall effects\n  in four-layer MnBi2Te4 antiferromagnets: Van der Waals (vdW) assembly could efficiently modulate the symmetry of\ntwo-dimensional (2D) materials that ultimately governs their physical\nproperties. Of particular interest is the ferroelectric polarization being\nintroduced by proper vdW assembly that enables the realization of novel\nelectronic, magnetic and transport properties of 2D materials. Four-layer\nantiferromagnetic MnBi2Te4 (F-MBT) offers an excellent platform to explore\nferroelectric polarization effects on magnetic order and topological transport\nproperties of nanomaterials. Here, by applying symmetry analyses and\ndensity-functional-theory calculations, the ferroelectric interface effects on\nmagnetic order, anomalous Hall effect (AHE) or even quantum AHE (QAHE) on the\nF-MBT are analyzed. Interlayer ferroelectric polarization in F-MBT efficiently\nviolates the PT symmetry (the combination symmetry of central inversion (P) and\ntime reverse (T) of the F-MBT by conferring magnetoelectric couplings, and\nstabilizes a specific antiferromagnetic order encompassing a ferromagnetic\ninterface in the F-MBT. We predict that engineering an interlayer polarization\nin the top or bottom interface of F-MBT allows converting F-MBT from a trivial\ninsulator to a Chern insulator. The switching of ferroelectric polarization at\nthe middle interfaces results in a direction reversal of the quantum anomalous\nHall current. Additionally, the interlayer polarization of the top and bottom\ninterfaces can be aligned in the same direction, and the switching of\npolarization direction also reverses the direction of anomalous Hall currents.\nOverall, our work highlights the occurrence of quantum-transport phenomena in\n2D vdW four-layer antiferromagnets through vdW assembly. These phenomena are\nabsent in the bulk or thin-film in bulk-like stacking forms of MnBi2Te4."
    },
    {
        "anchor": "Phase transitions and ferroelectricity in very thin films: single-\n  versus multidomain state: We discuss ferroelectric phase transitions into single- and multidomain\nstates in very thin films using continuous theory. It is shown that in nearly\ncubic ferroelectrics the domain state may survive down to atomic film\nthicknesses, unlike the single domain state, which is almost always unstable or\nmetastable. This conclusion is valid almost irrespective of the nature of\nelectrodes (metallic or semiconducting) and whether or not the screening\ncarriers may be present in the ferroelectric itself.",
        "positive": "Magnetic resonance in nanoparticles: between ferro- and paramagnetism: Magnetic nanoparticles of gamma-Fe2O3 coated by organic molecules and\nsuspended in liquid and solid matrices, as well as a non-diluted magnetic fluid\nhave been studied by electron magnetic resonance (EMR) at 77-380 K. Slightly\nasymmetric spectra observed at room temperature become much broader, symmetric,\nand shift to lower fields upon cooling. An additional narrow spectral component\n(with the line-width of 30 G) is found in the diluted samples, its magnitude\nobeying the Arrhenius law with the activation temperature of about 850 K. The\nlongitudinal spin-relaxation time, T1 >> 10 ns, was determined by the specially\ndeveloped modulation method. Angular dependence of the EMR signal position in\nfield-freezing samples unambiguously points to the domination of the uniaxial\nmagnetic anisotropy. Substantial alignment is achieved in moderate freezing\nfields of 4-5 kG, suggesting formation of dipolar-coupled chains consisting\nfrom several particles separated by organic nanolayers. The shift and\nbroadening of the spectrum upon cooling are ascribed to the role of the surface\nlayer, which is considered with taking into acount the strong surface-related\nanisotropy. To describe the overall spectrum shape, a quantization model is\nused which includes summation of the resonances corresponding to varios\norientations of the particle magnetic moment. This approach, supplemented with\nsome phenomenological assumptions, provides satisfactory agreement with the\nexperimental data."
    },
    {
        "anchor": "Pushing the Study of Point Defects in Thin Film Ferrites to Low\n  Temperatures Using In Situ Ellipsometry: Unveiling point defects concentration in transition metal oxide thin films is\nessential to understand and eventually control their functional properties,\nemployed in an increasing number of applications and devices. Despite this\nunquestionable interest, there is a lack of available experimental techniques\nable to estimate the defect chemistry and equilibrium constants in such oxides\nat intermediate-to-low temperatures. In this study, the defect chemistry of a\nrelevant material such as La1-xSrxFeO3-d (LSF) with (x = 0.2, 0.4 and 0.5\n(LSF20, LSF40 and LSF50 respectively) is obtained by using a novel in situ\nspectroscopic ellipsometry approach applied to thin films. Through this\ntechnique, the concentration of holes in LSF is correlated to measured optical\nproperties and its evolution with temperature and oxygen partial pressure is\ndetermined. In this way, a systematic description of defect chemistry in LSF\nthin films in the temperature range from 350dC to 500dC is obtained for the\nfirst time, which represents a step forward in the understanding of LSF20,\nLSF40 and LSF50 for emerging low temperature applications.",
        "positive": "Thermoelectric PbTe-CdTe bulk nanocomposite: The preparation method of thermoelectric PbTe-CdTe semiconductor\nnanocomposite in the form of a bulk material doped with Bi, I or Na, intended\nfor production the mid-temperature thermoelectric energy generators is\npresented. The method takes advantage of the extremely low mutual solubility of\nboth semiconductors, resulting from their different crystal structure, and is\nbased on a specifically designed Bridgman growth procedure. It is shown that\nthe formation of zinc-blende crystalline CdTe grains in the rock-salt matrix of\nthermoelectric PbTe can be forced during the synthesis of a composite by\nintroducing Cd in the form of CdTe compound and choosing the growth temperature\nabove the melting point of PbTe but below the melting point of CdTe. X-ray\ndiffraction and SEM-EDX spectroscopy analyzes as well as basic electric and\nthermoelectric characterization of the nanocomposite samples containing 2, 5\nand 10 at. \\% of Cd showed that using proposed growth procedure, it is possible\nto obtain both n-type (Bi- or I-doped) and p-type (Na-doped) material with\ncarrier concentration of 1{\\div}5 x 10\\^{19} cm\\^{-3} and uniformly distributed\nCdTe grains with a diameter of the order of 100 nm."
    },
    {
        "anchor": "Optical Response of DyN: We report measurements of the optical response of polycrystalline DyN thin\nfilms. The frequency-dependent complex refractive index in the near\nIR-visible-near UV was determined by fitting reflection/transmission spectra.\nIn conjunction with resistivity measurements these identify DyN as a\nsemiconductor with 1.2 eV optical gap. When doped by nitrogen vacancies it\nshows free carrier absorption and a blue-shifted gap associated with the\nMoss-Burstein effect. The refractive index of 2.0+/-0.1 depends only weakly on\nenergy. Far infrared reflectivity data show a polar phonon of frequency 280\ncm-1 and dielectric strength delta epsilon= 20.",
        "positive": "Hall mobilities and sheet carrier densities in a single LiNbO$_3$\n  conductive ferroelectric domain wall: For the last decade, conductive domain walls (CDWs) in single crystals of the\nuniaxial model ferroelectric lithium niobate (LiNbO$_3$, LNO) have shown to\nreach resistances more than 10 orders of magnitude lower as compared to the\nsurrounding bulk, with charge carriers being firmly confined to sheets of a few\nnanometers in width. LNO thus currently witnesses an increased attention since\nbearing the potential for variably designing room-temperature nanoelectronic\ncircuits and devices based on such CDWs. In this context, the reliable\ndetermination of the fundamental transport parameters of LNO CDWs, in\nparticular the 2D charge carrier density $n_{2D}$ and the Hall mobility\n$\\mu_{H}$ of the majority carriers, are of highest interest. In this\ncontribution, we present and apply a robust and easy-to-prepare Hall-effect\nmeasurement setup by adapting the standard 4-probe van-der-Pauw method to\ncontact a single, hexagonally-shaped domain wall that fully penetrates the\n200-$\\mu$m-thick LNO bulk single crystal. We then determine $n_{2D}$ and\n$\\mu_{H}$ for a set of external magnetic fields $B$ and prove the expected\ncosine-like angular dependence of the Hall voltage. Lastly, we present\nphoto-Hall measurements of one and the same DW, by determining the impact of\nsuper-bandgap illumination on the 2D charge carrier density $n_{2D}$."
    },
    {
        "anchor": "QED theory of electron beam-induced electronic excitation and its effect\n  on sputtering cross sections in 2D crystals: Many computational models have been developed to predict the rates of atomic\ndisplacements in two-dimensional (2D) materials under electron beam\nirradiation. However, these models often drastically underestimate the\ndisplacement rates in 2D insulators, in which beam-induced electronic\nexcitations can reduce the binding energies of the irradiated atoms. This bond\nsoftening leads to a qualitative disagreement between theory and experiment, in\nthat substantial sputtering is experimentally observed at beam energies deemed\nfar to small to drive atomic dislocation by many current models. To address\nthese theoretical shortcomings, this paper develops a first-principles method\nto calculate the probability of beam-induced electronic excitations by coupling\nquantum electrodynamics (QED) scattering amplitudes to density functional\ntheory (DFT) single-particle orbitals. The presented theory then explicitly\nconsiders the effect of these electronic excitations on the sputtering cross\nsection. Applying this method to 2D hexagonal BN and MoS$_2$ significantly\nincreases their calculated sputtering cross sections and correctly yields\nappreciable sputtering rates at beam energies previously predicted to leave the\ncrystals intact. The proposed QED-DFT approach can be easily extended to\ndescribe a rich variety of beam-driven phenomena in any crystalline material.",
        "positive": "The thermal stability and separation characteristic of anti-sticking\n  layers of Pt/Cr films for hot slumping technology: The thermal stability and separation characteristic of anti-sticking layers\nof Pt/Cr films were studied in this paper. Several types of adhesion layers\nwere investigated: 10.0 nm Pt, 1.5 nm Cr+50.0 nm Pt, 2.5 nm Cr+50.0 nm Pt and\n3.5 nm Cr+50.0 nm Pt fabricated using direct current magnetron sputtering. The\nvariation of layer thicknesses, roughness, crystallization and surface\ntopography of Pt/Cr films have been analyzed by grazing incidence X-ray\nreflectometry, large angle X-ray diffraction and the optical profiler before\nand after heating. 2.5 nm Cr+50.0 nm Pt films exhibit the best thermal\nstability and separation characteristic according to the heating and hot\nslumping experiments. The films were also applied as anti-sticking layers to\noptimize the maximum temperature of hot slumping technology."
    },
    {
        "anchor": "Examining the thermal conductivity of half-Heusler alloy TiNiSn by\n  first-principles calculations: The thermoelectric properties of half-Heusler alloy TiNiSn have been studied\nfor decade, however, theoretical report on its thermal conductivity is still\nlittle known, because it is difficult to estimate effectively the lattice\nthermal conductivity. In this work, we use the ShengBTE code developed recently\nto examine the lattice thermal conductivity of TiNiSn. The calculated lattice\nthermal conductivity at room temperature is 7.6 W/mK, which is close to the\nexperimental value of 8 W/mK. We also find that the total and lattice thermal\nconductivities dependent temperature are in good agreement with available\nexperiments, and the total thermal conductivity is dominated by the lattice\ncontribution. The present work is useful for the theoretical prediction of\nlattice thermal conductivity and the optimization of thermoelectric\nperformance.",
        "positive": "Electro-optic measurement of carrier mobility in an organic thin-film\n  transistor: We have used an electro-optic technique to measure the position-dependent\ninfrared absorption of holes injected into a thin crystal of the organic\nsemiconductor, 6,13-bis(triisopropylsilylethynyl)-pentacene incorporated in a\nfield-effect transistor. By applying square-wave voltages of variable frequency\nto the gate or drain, one can measure the time it takes for charges to\naccumulate on the surface, and therefore determine their mobility."
    },
    {
        "anchor": "Graphene oxyhydride catalysts in view of spin radical chemistry: The article discusses carbocatalysis provided with amorphous carbons. The\ndiscussion is conducted from the standpoint of the spin chemistry of graphene\nmolecules, in the framework of which the amorphous carbocatalysts are a\nconglomerate of graphene-oxynitrothiohydride stable radicals presenting the\nbasic structural units (BSUs) of the species. The chemical activity of the BSUs\natoms is reliably determined computationally, which allows mapping the\ndistribution of active sites in these molecular catalysts. The presented maps\nreliably evidence the BSUs radicalization provided with carbon atoms only, the\nnon-terminated edge part of which presents a set of active cites. Spin mapping\nof carbocatalysts active cites is suggested as the first step towards the spin\ncarbocatalysis of the species.",
        "positive": "Anisotropic carrier dynamics in a laser-excited\n  Fe$_{1}$/(MgO)$_{3}$(001) heterostructure from real-time time-dependent DFT: The interaction of a femtosecond optical pulse with a\nFe$_{1}$/(MgO)$_{3}$(001) metal/oxide heterostructure is investigated using\ntime-dependent density functional theory (TDDFT) calculations in the real-time\ndomain. We systematically study electronic excitations as a function of laser\nfrequency, peak power density and polarization direction. While spin-orbit\ncoupling is found to result in only a small time-dependent reduction of\nmagnetization (less than 10%), we find a marked anisotropy in the response to\nin-plane and out-of-plane polarized light, which changes its character\nqualitatively depending on the excitation energy: the Fe-layer is efficiently\naddressed at low frequencies by in-plane polarized light, whereas for\nfrequencies higher than the MgO band gap, we find a particularly strong\nresponse of the central MgO-layer for cross-plane polarized light. For laser\nexcitations between the charge transfer gap and the MgO band gap, the interface\nplays the most important role, as it mediates concerted transitions from the\nvalence band of MgO into the $3d$ states of Fe closely above the Fermi level\nand from the Fe-states below the Fermi level into the conduction band of MgO.\nAs these transitions can occur simultaneously altering charge balance of the\nlayers, they could potentially lead to an efficient transfer of excited\ncarriers into the MgO bulk, where the corresponding electron and hole states\ncan be separated by an energy which is significantly larger than the photon\nenergy."
    },
    {
        "anchor": "Dislocation drag from phonon wind in an isotropic crystal at large\n  velocities: The anharmonic interaction and scattering of phonons by a moving dislocation,\nthe photon wind, imparts a drag force $v B(v, T, \\rho)$ on the dislocation. In\nearly studies the drag coefficient $B$ was computed and experimentally\ndetermined only for dislocation velocities $v$ much less than transverse sound\nspeed, $c_t$. In this paper we derive analytic expressions for the velocity\ndependence of $B$ up to $c_t$ in terms of the third-order continuum elastic\nconstants of an isotropic crystal, in the continuum Debye approximation, valid\nfor dislocation velocities approaching the sound speed. In so doing we point\nout that the most general form of the third order elastic potential for such a\ncrystal and the dislocation-phonon interaction requires two additional elastic\nconstants involving asymmetric local rotational strains, which have been\nneglected previously. We compute the velocity dependence of the transverse\nphonon wind contribution to $B$ in the range 1%-90% $c_t$ for Al, Cu, Fe, and\nNb in the isotropic Debye approximation. The drag coefficient for transverse\nphonons scattering from screw dislocations is finite as $v \\rightarrow c_t$,\nwhereas $B$ is divergent for transverse phonons scattering from edge\ndislocations in the same limit. This divergence indicates the breakdown of the\nDebye approximation and sensitivity of the drag coefficient at very high\nvelocities to the microscopic crystalline lattice cutoff. We compare our\nresults to experimental results wherever possible and identify ways to validate\nand further improve the theory of dislocation drag at high velocities with\nrealistic phonon dispersion relations, inclusion of lattice cutoff effects, MD\nsimulation data, and more accurate experimental measurements.",
        "positive": "A resistive electron irradiation microsensor made from conductive\n  electrospun polycaprolactone fibers loaded with carbon nanotubes and\n  fullerene C60: In this work an electron radiation detector microdevices were fabricated and\ncharacterized. The devices consisted of a conductive electrospun mat made of\npolycaprolactone loaded with multiwalled carbon nanotubes and fullerene C60\ndeposited onto gold interdigitated microelectrodes. They were capable of\npermanently increase their conductivity upon exposure to electron beam\nirradiation from 0.02 pC/{\\mu}m2 accelerated at 10 and 20 keV. This phenomenon\ncould be explained due to the ability of C60 to trap and stabilize negative\ncharges and thus contribute to the conductivity of the polymer composite. The\ndevices achieved their maximum conductivity at an irradiation between 0.22 and\n0.27 pC/{\\mu}m2 and this maximum was dependent of the electron acceleration.\nMontecarlo simulations were performed to explain dependence as function of\nelectron penetration in the polymer composite. Moreover, the devices irradiated\nat 20keV maintained their final conductivity and the devices irradiated at\n10keV increased their final conductivity after 6 days from irradiation.\nFullerenes proved to act as highly efficient electron scavengers within the\npolymer composite and contribute to its conductivity, and the microdevice has\npotential application as beta radiation sensors."
    },
    {
        "anchor": "A minimal Tersoff potential for diamond silicon with improved\n  descriptions of elastic and phonon transport properties: Silicon is an important material and many empirical interatomic potentials\nhave been developed for atomistic simulations of it. Among them, the Tersoff\npotential and its variants are the most popular ones. However, all the existing\nTersoff-like potentials fail to reproduce the experimentally measured thermal\nconductivity of diamond silicon. Here we propose a modified Tersoff potential\nand develop an efficient open source code called GPUGA (graphics processing\nunits genetic algorithm) based on the genetic algorithm and use it to fit the\npotential parameters against energy, virial and force data from quantum density\nfunctional theory calculations. This potential, which is implemented in the\nefficient open source GPUMD (graphics processing units molecular dynamics)\ncode, gives significantly improved descriptions of the thermal conductivity and\nphonon dispersion of diamond silicon as compared to previous Tersoff potentials\nand at the same time well reproduces the elastic constants. Furthermore, we\nfind that quantum effects on the thermal conductivity of diamond silicon at\nroom temperature are non-negligible but small: using classical statistics\nunderestimates the thermal conductivity by about 10\\% as compared to using\nquantum statistics.",
        "positive": "Tailoring between network rigidity and nanosecond transient absorption\n  in a-GexAs35-xSe65 thin films: In this letter, we report the first observation of dramatic decrease in\nnanosecond (ns) pulsed laser induced transient absorption (TA) in\na-GexAs35-xSe65 thin films by tuning the amorphous network from floppy to\nrigid. Our results provide the direct experimental evidence of a self trapped\nexciton mechanism, where trapping of the excitons occurs through bond\nrearrangements. Taken together, a rigid amorphous network with more constraints\nthan degrees of freedom, are unable to undergo any such bond rearrangements and\nresults in weaker TA. However, we also demonstrate that excitation fluence can\nbe effectively utilized as a simple tool to lift up enough constraints to\nintroduce large TA even in rigid networks. Apart from this, we also show that\nTA is tunable with network rigidity as it blueshift when the mean coordination\nis increased from 2.35 to 2.6."
    },
    {
        "anchor": "Harnessing van der Waals CrPS4 and Surface Oxides for non-monotonic\n  pre-set field induced Exchange Bias in Fe3GeTe2: Two-dimensional van der Waals (vdW) heterostructures are an attractive\nplatform for studying exchange bias due to their defect free and atomically\nflat interfaces. Chromium thiophosphate (CrPS4), an antiferromagnetic material,\npossesses uncompensated magnetic spins in a single layer, rendering it a\npromising candidate for exploring exchange bias phenomena. Recent findings have\nhighlighted that naturally oxidized vdW ferromagnetic Fe3GeTe2 exhibits\nexchange bias, attributed to the antiferromagnetic coupling of its ultrathin\nsurface oxide layer (O-FGT) with the underlying unoxidized Fe3GeTe2. Anomalous\nHall measurements are employed to scrutinize the exchange bias within the\nCrPS4/(O-FGT)/Fe3GeTe2 heterostructure. This analysis takes into account the\ncontributions from both the perfectly uncompensated interfacial CrPS4 layer and\nthe interfacial oxide layer. Intriguingly, a distinct and non-monotonic\nexchange bias trend is observed as a function of temperature below 140 K. The\noccurrence of exchange bias induced by a 'pre-set field' implies that the\nprevailing phase in the polycrystalline surface oxide is ferrimagnetic Fe3O4.\nMoreover, the exchange bias induced by the ferrimagnetic Fe3O4 is significantly\nmodulated by the presence of the van der Waals antiferromagnetic CrPS4 layer,\nforming a heterostructure, along with additional iron oxide phases within the\noxide layer. These findings underscore the intricate and complex nature of\nexchange bias in van der Waals heterostructures, highlighting their potential\nfor tailored manipulation and control.",
        "positive": "Stacking-Dependent Spatial Charge Separation in Graphitic Carbonic\n  Nitride layers: We reveal the existence of stacking-dependent spatial(SDS) charge separation\nin graphitic carbonic nitride (g-C3N4) layers, with the density functional\ntheory (DFT) calculations. In g-C3N4 bilayers, such SDS charge separation is\nfound in particular effective for top valence bands that can drive electrons\n100% away from one layer to the other. However, for bottom conduction ones, it\nresults in little charge redistribution between layers. As spatial charge\nseparation naturally suppresses the electron-hole recombination, that makes\ng-C3N4 layers with proper stacking much more efficient for harvesting solar\nenergy in photovoltaic or photocatalytic applications. The SDS charge\nseparation has been understood as a result of the inter-layer quantum\nentanglement from those g-C3N4 band electrons, whose unique chirality and\nphases in corner-atom-shared C6N10 units are relatively isolated and in tune\nonly through the corner N atoms. The SDS charge separation in g-C3N4 may lead\nto an intrinsic way, i.e. without alien dopings, interfaces or electrical\nfields, to manipulate charge carriers in semiconducting materials. That may\nlead to new physics in the future optoelectronics or electronics of\ntwo-dimensional (2D) materials, such as realizing the layer-selected charge\ntransport through the bilayer or multi-layer 2D materials."
    },
    {
        "anchor": "Photo-Hall effect spectroscopy with enhanced illumination in\n  p-Cd1-xMnxTe showing negative differential photoconductivity: We studied deep levels (DLs) in p-type CdMnTe by photo-Hall effect\nspectroscopy with enhanced illumination. We showed that the mobility of\nminority and majority carriers can be deduced directly from the spectra by\nusing proper wavelength and excitation intensity. Four deep levels with\nionization energies 0.63 eV, 0.9 eV, 1.0 eV and 1.3 eV were detected and their\npositions in the bandgap were verified by comparison of photogenerated electron\nand hole concentrations. Deduced DL model was analyzed by numerical simulations\nwith Shockley-Reed-Hall charge generation-recombination theory and compared\nwith alternative DL models differing in the position of selected DLs relative\nto Ec and Ev. We showed that the consistent explanation of collected\nexperimental data principally limits the applicability of alternative DLs\nmodels. We also demonstrated the importance of the extended operation photon\nfluxes used in the spectra acquisition for correct determination of DLs\ncharacter. Negative differential photoconductivity was observed and studied by\ncharge dynamic theoretical simulations.",
        "positive": "Manifestation of finite temperature size effects in nanogranular\n  magnetic graphite: In addition to the double phase transition (with the Curie temperatures\nT_C=300K and T_{Ct}=144K), a low-temperature anomaly in the dependence of the\nmagnetization is observed in the bulk magnetic graphite (with an average\ngranular size of L=10nm), which is attributed to manifestation of the size\neffects below the quantum temperature. The best fits of the high-temperature\ndata (using the mean-field Curie-Weiss and Bloch expressions) produced\nreasonable estimates for the model parameters, such as defects mediated\neffective spin exchange energy J=12meV (which defines the intragranular Curie\ntemperature T_C) and proximity mediated interactions between neighboring grains\n(through potential barriers created by thin layers of non-magnetic graphite)\nwith energy J_t=exp(-d/s)J=5.8meV (which defines the intergranular Curie\ntemperature T_{Ct}) with d=1.5nm and s=2nm being the intergranular distance and\ncharacteristic length, respectively."
    },
    {
        "anchor": "Normal and anti Meyer-Neldel rule in conductivity of highly crystallized\n  undoped microcrystalline silicon films: We have studied the electrical conductivity behavior of highly crystallized\nundoped hydrogenated microcrystalline silicon films having different\nmicrostructures. The dark conductivity is seen to follow Meyer Neldel rule\n(MNR) in some films and anti MNR in others, which has been explained on the\nbasis of variation in the film microstructure and the corresponding changes in\nthe effective density of states distributions. A band tail transport and\nstatistical shift of Fermi level are used to explain the origin of MNR as well\nas anti-MNR in our samples. The observation of MNR and anti MNR in electrical\ntransport behavior of microcrystalline silicon is discussed in terms of the\nbasic underlying physics of their origin and the significance of these\nrelationships.",
        "positive": "Deviations from Matthiessen rule and resistivity saturation effects in\n  Gd and Fe: According to earlier first-principles calculations, the spin-disorder\ncontribution to the resistivity of rare-earth metals in the paramagnetic state\nis strongly underestimated if Matthiessen's rule is assumed to hold. To\nunderstand this discrepancy, the resistivity of paramagnetic Fe and Gd is\nevaluated by taking into account both spin and phonon disorder. Calculations\nare performed using the supercell approach within the linear muffin-tin orbital\nmethod. Phonon disorder is modeled by introducing random displacements of the\natomic nuclei, and the results are compared with the case of fictitious\nAnderson disorder. In both cases the resistivity shows a nonlinear dependence\non the square of the disorder potential, which is interpreted as a resistivity\nsaturation effect. This effect is much stronger in Gd than in Fe. The\nnon-linearity makes the phonon and spin-disorder contributions to the\nresistivity non-additive, and the standard procedure of extracting the\nspin-disorder resistivity by extrapolation from high temperatures becomes\nambiguous. An \"apparent\" spin-disorder resistivity obtained through such\nextrapolation is in much better agreement with experiment compared to the\nresults obtained by considering only spin disorder. By analyzing the spectral\nfunction of the paramagnetic Gd in the presence of Anderson disorder, the\nresistivity saturation is explained by the collapse of a large area of the\nFermi surface due to the disorder-induced mixing between the electronic and\nhole sheets."
    },
    {
        "anchor": "Accelerating off-lattice kinetic Monte Carlo simulations to predict\n  hydrogen vacancy-cluster interactions in $\u03b1$-Fe: We present an enhanced off-lattice kinetic Monte Carlo (OLKMC) model, based\non a new method for tolerant classification of atomistic local-environments\nthat is invariant under Euclidean-transformations and permutations of atoms.\nOur method ensures that environments within a norm-based tolerance are\nclassified as equivalent. During OLKMC simulations, our method guarantees to\nelide the maximum number of redundant saddle-point searches in symmetrically\nequivalent local-environments. Hence, we are able to study the\ntrapping/detrapping of hydrogen from up to five-vacancy clusters and\nsimultaneously the effect hydrogen has on the diffusivity of these clusters.\nThese processes occur at vastly different timescales at room temperature in\nbody-centred cubic iron. We are able to predict the diffusion pathways of\nclusters/complexes without a priori assumptions of their mechanisms, not only\nreproducing previously reported mechanisms but also discovering new ones for\nlarger complexes. We detail the hydrogen-induced changes in the clusters'\ndiffusion mechanisms and find evidence that, in contrast to mono-vacancies, the\nintroduction of hydrogen to larger clusters can increase their diffusivity. We\ncompare the effective hydrogen diffusivity to Oriani's classical theory of\ntrapping, finding general agreement and some evidence that hydrogen may not\nalways be in equilibrium with traps, when the traps are mobile. Finally, we are\nable to compute the trapping atmosphere of meta-stable states surrounding\nnon-point traps, opening new avenues to better understand and predict hydrogen\nembrittlement in complex alloys.",
        "positive": "Screening and Many-Body Effects in Two-Dimensional Crystals: Monolayer\n  MoS$_{2}$: We present a systematic study of the variables affecting the electronic and\noptical properties of two-dimensional(2D) crystals within \\textit{ab initio} GW\nand GW plus Bethe Salpeter Equation (GW-BSE) calculations. As a prototypical 2D\ntransition metal dichalcogenide material, we focus our study on monolayer\nMoS${}_2$. We find that the reported variations in GW-BSE results in the\nliterature for monolayer MoS${}_2$ and related systems arise from different\ntreatments of the long-range Coulomb interaction in supercell calculations and\nconvergence of k-grid sampling and cutoffs for various quantities such as the\ndielectric screening. In particular, the quasi-2D nature of the system gives\nrise to fast spatial variations in the screening environment, which are\ncomputationally challenging to resolve. We also show that common numerical\ntreatments to remove the divergence in the Coulomb interaction can shift the\nexciton continuum leading to false convergence with respect to k-point\nsampling. Our findings apply to GW-BSE calculations on any low-dimensional\nsemiconductors."
    },
    {
        "anchor": "Microwave Conductivity of Ferroelectric Domains and Domain Walls in\n  Hexagonal Rare-earth Ferrite: We report the nanoscale electrical imaging results in hexagonal\n$Lu_{0.6}Sc_{0.4}FeO_3$ single crystals using conductive atomic force\nmicroscopy (C-AFM) and scanning microwave impedance microscopy (MIM). While the\ndc and ac response of the ferroelectric domains can be explained by the surface\nband bending, the drastic enhancement of domain wall (DW) ac conductivity is\nclearly dominated by the dielectric loss due to DW vibration rather than\nmobile-carrier conduction. Our work provides a unified physical picture to\ndescribe the local conductivity of ferroelectric domains and domain walls,\nwhich will be important for future incorporation of electrical conduction,\nstructural dynamics, and multiferroicity into high-frequency nano-devices.",
        "positive": "First principle investigation of hydrogen behavior in M doped Cu$_2$O (M\n  $=$ Na, Li and Ti): We study the hydrogen effect on the electronic, magnetic and optical\nproperties of Cu$_2$O in presence of different dopants (Na, Li and Ti). The\nelectronic properties calculations show that hydrogen changes the conductivity\nof Cu$_2$O from p to n-type. The results show that interstitial hydrogen atom\nprefers to locate in the tetrahedral site in Cu$_2$O system and it decreases\nthe band gap value of the later. The Na or Li doping Cu$_2$O preserves the\np-type conductivity of Cu$_2$O, while hydrogen is the source of n-type\nconductivity in Na or Li doped Cu$_2$O systems. Ti doping increases the band\ngap value of Cu$_2$O and makes it an n-type semiconductor. Hydrogen increases\nthe optical transmittance of M doped Cu$_2$O."
    },
    {
        "anchor": "Strain-induced perpendicular magnetic anisotropy in\n  La$_2$CoMnO$_{6-\u03b5}$ thin films and its dependence with film thickness: Ferromagnetic insulating La$_2$CoMnO$_{6-\\epsilon}$ (LCMO) epitaxial thin\nfilms grown on top of SrTiO$_3$ (001) substrates presents a strong magnetic\nanisotropy favoring the out of plane orientation of the magnetization with a\nstrong anisotropy field ($\\sim 70$ kOe for film thickness of about 15 nm) and\nwith a coercive field of about 10 kOe. The anisotropy can be tuned by modifying\nthe oxygen content of the film which indirectly has two effects on the unit\ncell: i) change of the orientation of the LCMO crystallographic axis over the\nsubstrate (from c in-plane to c out-of-plane) and ii) shrinkage of the out of\nplane cell parameter, which implies increasing tensile strain of the films. In\ncontrast, LCMO films grown on (LaAlO$_3$)$_{0.3}$(Sr$_2$AlTaO$_6$)$_{0.7}$ and\nLaAlO$_3$ substrates (with a larger out-of-plane lattice parameter and\ncompressive stress) display in-plane magnetic anisotropy. Thus, we link the\nstrong magnetic anisotropy observed in La$_2$CoMnO$_{6-\\epsilon}$ to the\nrelation between in-plane and out-of-plane parameters and so to the film\nstress.",
        "positive": "Application of canonical augmentation to the atomic substitution problem: A common approach for studying a solid solution or disordered system within a\nperiodic ab-initio framework is to create a supercell in which a certain amount\nof target elements is substituted with other ones. The key to generating\nsupercells is determining how to eliminate symmetry-equivalent structures from\nthe large number of substitution patterns. Although the total number of\nsubstitutions is on the order of trillions, only symmetry-inequivalent atomic\nsubstitution patterns need to be identified, and their number is far smaller\nthan the total. A straightforward solution would be to classify them after\ndetermining all possible patterns, but it is redundant and practically\nunfeasible. Therefore, to alleviate this drawback, we developed a new formalism\nbased on the {\\it canonical augmentation}, and successfully applied it to the\natomic substitution problem. Our developed \\verb|python| software package,\nwhich is called \\textsc{SHRY} (\\underline{S}uite for\n\\underline{H}igh-th\\underline{r}oughput generation of models with atomic\nsubstitutions implemented by p\\underline{y}thon), enables us to pick up only\nsymmetry-inequivalent structures from the vast number of candidates very\nefficiently. We demonstrate that the computational time required by our\nalgorithm to find $N$ symmetry-inequivalent structures scales {\\it linearly}\nwith $N$ up to $\\sim 10^9$. This is the best scaling for such problems."
    },
    {
        "anchor": "Electronic and optical properties of SnX2(X=S, Se)-InSe van der Waals\n  heterostructures from first- principle calculations: In this work from first-principles simulations we investigate bilayer van der\nWaals heterostructures (vdWh) of emerging 2-dimensional (2D) optical materials\nSnS 2 and SnSe 2 with monolayer InSe. With density functional theory (DFT)\ncalculations, we study the structural, electronic, optical and carrier\ntransport properties of the SnX 2 (X=S,Se)-InSe vdWh. Calculations show SnX 2\n-InSe in its most stable stacking form (named AB-1) to be a material with a\nsmall (0.6- 0.7eV) indirect band-gap. The bilayer vdWh shows broad spectrum\noptical response, with number of peaks in the infra-red to visible region. In\nterms of carrier transport properties, asymmetry in conductance was observed\nwith respect to the transport direction and electron and hole transmission. The\nfindings are promising from the viewpoint of nanoelectronics and photonics.",
        "positive": "Synthesis, floating zone crystal growth and characterization of the\n  Quantum Spin Ice $\\rm Pr_2Zr_2O_7$ pyrochlore: Pyrochlore $\\rm Pr^{3+}_{2+x}Zr^{4+}_{2-x}O_{7-x/2}$ samples in the form of\nboth powders $(-0.02 \\le x \\le 0.02)$ and bulk single crystals have been\nstudied to elucidate the dependence of their magnetic, compositional and\nstructural properties on synthesis and growth conditions. All samples were\ncharacterized using X-ray diffraction, specific heat, and DC magnetization\nmeasurements. The crystals were also studied using the X-ray Laue technique and\nscanning electron microscopy. Increasing the Pr content for the $\\rm\nPr_{2+x}Zr_{2-x}O_{7-x/2}$ powders enlarged the lattice parameter, and resulted\nin systematic changes in magnetic susceptibility and specific heat.\nStoichiometric and high quality single crystals of $\\rm Pr_2Zr_2O_7$ were grown\nusing the optical floating zone technique under a high purity static argon\natmosphere, to avoid inclusions of Pr$^{4+}$ and limit Pr vaporization.\nIncreasing the growth speed was found to significantly reduce Pr vaporization\nfor better control of stoichiometry. Scanning electron microscopy provided\ndirect evidence of spinodal decomposition during growth that is controllable\nvia rotation rate. An intermediate rotation rate of 3-6 rpm was found to\nproduce the best microstructure. The magnetic susceptibility of crystals grown\nat rates from 1-20 mm/hr revealed changes that were consistent with Pr\nvaporization. Further, we report indications of local off-centering of\nPr$^{3+}$ ions from the ideal pyrochlore sites, similar to what is known for\nthe trivalent cation in $\\rm Bi_2Ti_2O_7$ and $\\rm La_2Zr_2O_7$. The effect\nvaries with Pr content and radically modulates the low temperature specific\nheat. Overall, the results clearly demonstrate important correlations between\nthe growth conditions and physical properties of $\\rm Pr_2Zr_2O_7$ crystals."
    },
    {
        "anchor": "The structure, energy, and electronic states of vacancies in Ge\n  nanocrystals: The atomic structure, energy of formation, and electronic states of vacancies\nin H-passivated Ge nanocrystals are studied by density functional theory (DFT)\nmethods. The competition between quantum self-purification and the free surface\nrelaxations is investigated. The free surfaces of crystals smaller than 2 nm\ndistort the Jahn-Teller relaxation and enhance the reconstruction bonds. This\nincreases the energy splitting of the quantum states and reduces the energy of\nformation to as low as 1 eV per defect in the smallest nanocrystals. In\ncrystals larger than 2 nm the observed symmetry of the Jahn-Teller distortion\nmatches the symmetry expected for bulk Ge crystals. Near the nanocrystal's\nsurface the vacancy is found to have an energy of formation no larger than 0.5\nto 1.4 eV per defect, but a vacancy more than 0.7 nm inside the surface has an\nenergy of formation that is the same as in bulk Ge. No evidence of the\nself-purification effect is observed; the dominant effect is the free surface\nrelaxations, which allow for the enhanced reconstruction. From the evidence in\nthis paper, it is predicted that for moderate sized Ge nanocrystals a vacancy\ninside the crystal will behave bulk-like and not interact strongly with the\nsurface, except when it is within 0.7 nm of the surface.",
        "positive": "Symmetry-Driven Valleytronics in Single-Layer Tin Chalcogenides: The concept of valleytronics has recently gained considerable research\nattention due to its intriguing physical phenomena and practical applications\nin optoelectronics and quantum information. In this study, by employing GW-BSE\ncalculations and symmetry analysis, we demonstrate that single-layer\northorhombic SnS and SnSe possess high carrier mobility and exceptional\nexcitonic effects. Especially, these materials display spontaneous linearly\npolarized optical selectivity, a behavior that differs from the\nvalley-selective circular dichroism observed in the hexagonal lattices.\nSpecifically, when subjected to a zigzag polarization of light, only the A\nexciton (stemming from the X valley) becomes optically active, while the B\nexciton (arising from the Y valley) remains dark. The armchair-polarized light\ntriggers the opposite behavior. This selective optical excitation arises from\nthe symmetry of the bands under mirror symmetry. Additionally, the study\nreveals a strong coupling between valley physics and ferroelectricity in\nlayered tin chalcogenides, enabling the manipulation of electronic transport\nand exciton polarization. Layered tin chalcogenides thus emerge as promising\ncandidates for both valleytronic and ferroelectric materials."
    },
    {
        "anchor": "Plasma induced surface modification of sapphire and its influence on\n  graphene grown by PECVD: The catalyst-free synthesis of graphene on dielectrics prevents the damage\ninduced by the transfer process. Although challenging, to master this synthesis\nwould boost the integration of graphene on consumer electronics since defects\nhinder its optoelectronic properties. In this work, the influence of the\ndifferent surface terminations of c-plane sapphire substrates on the synthesis\nof graphene via plasma-enhanced chemical vapour deposition (PECVD) is studied.\nThe different terminations of the sapphire surface are controlled by a plasma\netching process. A design of experiments (DoE) procedure was carried out to\nevaluate the major effects governing the etching process of four different\nparameters: i.e. discharge power, time, pressure and gas employed. In the\ncharacterization of the substrate, two sapphire surface terminations were\nidentified and characterized by means of contact angle measurements, being a\nhydrophilic (hydrophobic) surface the fingerprint of an Al- (OH-) terminated\nsurface, respectively. The defects within the synthesized graphene were\nanalysed by Raman spectroscopy. Notably, we found that the ID/IG ratio\ndecreases for graphene grown on OH-terminated surfaces. Furthermore, two\ndifferent regimes related to the nature of graphene defects were identified and\ndepending on the sapphire terminated surface are bound either to vacancy or\nboundary like defects. Finally, studying the density of defects and the\ncrystallite area, as well as their relationship with the sapphire surface\ntermination paves the way for increasing the crystallinity of the synthesized\ngraphene.",
        "positive": "Mechanical consequences of dynamically loaded NiTi wires under typical\n  actuator conditions in rehabilitation and neuroscience: In the field of rehabilitation and neuroscience shape memory alloys play a\ncrucial role as lightweight actuators. Devices are exploiting the shape memory\neffect by transforming heat into mechanical work. In rehabilitation\napplications, dynamic loading of the respective device occurs, which in turn\ninfluences the mechanical consequences of the phase transforming alloy. Hence\nin this work, dynamic thermomechanical material behavior of temperature\ntriggered phase transforming NiTi shape memory alloy wires with different\nchemical compositions and geometries is experimentally investigated. Storage\nmodulus and mechanical loss factor of NiTi alloys at different temperatures and\nloading frequencies are analyzed under force controlled conditions.\nCounterintuitive storage modulus and loss factor dependent trends regarding the\nloading frequency dependency of the mechanical properties on the materials\ncomposition and geometry are hence obtained. It could be revealed that loss\nfactors show a pronounced loading frequency dependency, whereas the storage\nmodulus was not affected. It is shown that force controlled conditions lead to\na lower storage modulus than expected. Further it turned out that a simple\nempirical relation can capture the characteristic temperature dependency of the\nstorage modulus, which is an important input relation for modeling the\nrehabilitation device behavior under different dynamic and temperature loading\nconditions, taking directly into account the material behavior of the shape\nmemory alloy."
    },
    {
        "anchor": "Direct experimental evidence for substrate adatom incorporation into a\n  molecular overlayer: While the phenomenon of metal substrate adatom incorporation into molecular\noverlayers is generally believed to occur in several systems, the experimental\nevidence for this relies on the interpretation of scanning tunnelling\nmicroscopy (STM) images, which can be ambiguous and provides no quantitative\nstructural information. We show that surface X-ray diffraction (SXRD) uniquely\nprovides unambiguous identification of these metal adatoms. We present the\nresults of a detailed structural study of the Au(111)-F4TCNQ system, combining\nsurface characterisation by STM, low energy electron diffraction and soft X-ray\nphotoelectron spectroscopy with quantitative experimental structural\ninformation from normal incidence X-ray standing waves (NIXSW) and SXRD,\ntogether with dispersion corrected density functional theory (DFT)\ncalculations. Excellent agreement is found between the NIXSW data and the DFT\ncalculations regarding the height and conformation of the adsorbed molecule,\nwhich has a twisted geometry rather than the previously supposed inverted bowl\nshape. SXRD measurements provide unequivocal evidence for the presence and\nlocation of Au adatoms, while the DFT calculations show this reconstruction to\nbe strongly energetically favoured.",
        "positive": "Effect of various electron and hole transport layers on the performance\n  of CsPbI3-based perovskite solar cells: A numerical investigation in DFT,\n  SCAPS-1D, and wxAMPS frameworks: CsPbI3 has recently received tremendous attention as a possible absorber of\nperovskite solar cells (PSCs). However, CsPbI3-based PSCs have yet to achieve\nthe high performance of the hybrid PSCs. In this work, we performed a density\nfunctional theory (DFT) study using the Cambridge Serial Total Energy Package\n(CASTEP) code for the cubic CsPbI3 absorber to compare and evaluate its\nstructural, electronic, and optical properties. The calculated electronic band\ngap (Eg) using the GGA-PBE approach of CASTEP was 1.483 eV for this CsPbI3\nabsorber. Moreover, the computed density of states (DOS) exhibited the dominant\ncontribution from the Pb-5d orbital, and most charge also accumulated for the\nPb atom as seen from the electronic charge density map. Fermi surface\ncalculation showed multiband character, and optical properties were computed to\ninvestigate the optical response of CsPbI3. Furthermore, we used IGZO, SnO2,\nWS2, CeO2, PCBM, TiO2, ZnO, and C60 as the electron transport layers (ETLs),\nand Cu2O, CuSCN, CuSbS2, Spiro-MeOTAD, V2O5, CBTS, CFTS, P3HT, PEDOT: PSS, NiO,\nCuO, and CuI as the hole transport layers (HTLs) to identify the best\nHTL/CsPbI3/ETL combinations using the SCAPS-1D solar cell simulation software.\nAmong 96 device structures, the best-optimized device structure,\nITO/TiO2/CsPbI3/CBTS/Au was identified, which exhibited an efficiency of 17.9%.\nThe effect of absorber and ETL thickness, series resistance, shunt resistance,\nand operating temperature was also evaluated for the six best devices along\nwith their corresponding generation rate, recombination rate,\ncapacitance-voltage, current density-voltage, and quantum efficiency\ncharacteristics. The obtained results from SCAPS-1D were also compared with\nwxAMPS simulation software."
    },
    {
        "anchor": "Thermal conductivity of Bi$_2$Se$_3$ from bulk to thin films: theory and\n  experiment: We calculate the lattice-driven in-plane $(\\kappa_{\\parallel})$ and\nout-of-plane $(\\kappa_{\\perp})$ thermal conductivities of Bi$_2$Se$_3$ bulk,\nand of films of different thicknesses, using the Boltzmann equation with phonon\nscattering times obtained from anharmonic third order density functional\nperturbation theory.\n  We compare our results for the lattice component of the thermal conductivity\nwith published data for $\\kappa_{\\parallel}$ on bulk samples and with our\nroom-temperature thermoreflectance measurements of $\\kappa_{\\perp}$ on films of\nthickness (L) ranging from 18~nm to 191~nm, where the lattice component has\nbeen extracted via the Wiedemann-Franz law. Ab-initio theoretical calculations\non bulk samples, including an effective model to account for finite sample\nthickness and defect scattering, compare favorably both for the bulk case (from\nliterature) and thin films (new measurements). In the low-T limit the\ntheoretical in-plane lattice thermal conductivity of bulk Bi$_2$Se$_3$ agrees\nwith previous measurements by assuming the occurrence of intercalated Bi$_2$\nlayer defects. The measured thermal conductivity monotonically decreases by\nreducing $L$, its value is $\\kappa_{\\perp}\\approx 0.39\\pm 0.08$~W/m$\\cdot$K for\n$L=18$ nm and $\\kappa_{\\perp}=0.68\\pm0.14$~W/m$\\cdot$K for $L=191$ nm. We show\nthat the decrease of room-temperature $\\kappa_{\\perp}$ in Bi$_2$Se$_3$ thin\nfilms as a function of sample thickness can be explained by the incoherent\nscattering of out-of-plane momentum phonons with the film surface. Our work\noutlines the crucial role of sample thinning in reducing the out-of-plane\nthermal conductivity.",
        "positive": "Multiple relaxation times in single-molecule magnets: Multiple relaxation times detected in the ac magnetic susceptibility of\nseveral single-molecule magnets have been always assigned to extrinsic factors,\nsuch as nonequivalent magnetic centers or effects of intermolecular\ninteractions in the crystal. By solving quantum relaxation equations, we prove\nthat the observed multiple relaxation times can be of intramolecular origin and\ncan show up even in single-ion metal complexes. For the latter a remarkably\ngood description of the coexistent two relaxation times is demonstrated on\nseveral experimental examples. This proves the relevance of the intramolecular\nmechanism of multiple relaxation times in such systems, which is even easier\njustified in polynuclear magnetic complexes."
    },
    {
        "anchor": "Reinvestigation of the intrinsic magnetic properties of\n  (Fe$_{1-x}$Co$_x$)$_2$B alloys and crystallization behavior of ribbons: New determination of the magnetic anisotropy from single crystals of\n(Fe$_{1-x}$Co$_x$)$_2$B alloys are presented. The anomalous temperature\ndependence of the anisotropy constant is discussed using the standard\nCallen-Callen theory, which is shown to be insufficient to explain the\nexperimental results. A more material specific study using first-principles\ncalculations with disordered moments approach gives a much more consistent\ninterpretation of the experimental data. Since the intrinsic properties of the\nalloys with $x=0.3-0.35$ are promising for permanent magnets applications,\ninitial investigation of the extrinsic properties are described, in particular\nthe crystallization of melt spun ribbons with Cu, Al, and Ti additions.\nPrevious attempts at developing a significant hysteresis have been unsuccessful\nin this system. Our melt-spinning experiment indicates that this system shows\nrapid crystallization.",
        "positive": "The influence of antiphase boundary of the MnAl $\u03c4$-phase on the\n  energy product: In this work we use a multiscale approach toward a realistic design of a\npermanent magnet based on MnAl $\\tau$-phase and elucidate how the antiphase\nboundary defects present in this material affect the energy product. We show\nhow the extrinsic properties of a microstructure depend on the intrinsic\nproperties of a structure with defects by performing micromagnetic simulations.\nFor an accurate estimation of the energy product of a realistic permanent\nmagnet based on the MnAl $\\tau$-phase with antiphase boundaries, we quantify\nfor the first time the exchange interaction strength across the antiphase\nboundary defect with a simple approach derived from the first-principles\ncalculations. These two types of calculations performed at different scales are\nlinked via atomistic spin dynamic simulations performed at an intermediate\nscale."
    },
    {
        "anchor": "Atomically Resolved Imaging of Highly Ordered Alternating Fluorinated\n  Graphene: One of the most desirable goals of graphene research is to produce ordered 2D\nchemical derivatives of suitable quality for monolayer device fabrication. Here\nwe reveal, by focal series exit wave reconstruction, that C2F chair is a stable\ngraphene derivative and demonstrates pristine long-range order limited only by\nthe size of a functionalized domain. Focal series of images of graphene and C2F\nchair formed by reaction with XeF2 were obtained at 80 kV in an\naberration-corrected transmission electron microscope. EWR images reveal that\nsingle carbon atoms and carbon-fluorine pairs in C2F chair alternate strictly\nover domain sizes of at least 150 nm^2 with electron diffraction indicating\nordered domains >/= 0.16 square micrometer. Our results also indicate that,\nwithin an ordered domain, functionalization occurs on one side only as theory\npredicts. Additionally we show that electron diffraction provides a quick and\neasy method for distinguishing between graphene, C2F chair and fully\nfluorinated stoichiometric CF 2D phases.",
        "positive": "A high-throughput and data-mining approach to predict new rare-earth\n  free permanent magnets: We present an application of a high-throughput search of new rare-earth free\npermanent magnets focusing on 3d-5d transition metal compounds. The search\ninvolved a part of the ICSD database (international crystallographic structural\ndatabase), together with tailored search criteria and electronic structure\ncalculations of magnetic properties. Our results suggest that it possible to\nfind candidates for rare-earth free permanent magnets using a\ndata-mining/data-filtering approach. The most promising candidates identified\nhere are Pt$_2$FeNi, Pt$_2$FeCu, and W$_2$FeB$_2$. We suggest these materials\nto be a good platform for further investigations in the search of novel\nrare-earth free permanent magnets."
    },
    {
        "anchor": "Physics of Silicene Stripes: Silicene, a monolayer of silicon atoms tightly packed into a two-dimensional\nhoneycomb lattice, is the challenging hypothetical reflection in the silicon\nrealm of graphene, a one-atom thick graphite sheet, presently the hottest\nmaterial in condensed matter physics. If existing, it would also reveal a\ncornucopia of new physics and potential applications. Here, we reveal the\nepitaxial growth of silicene stripes self-aligned in a massively parallel array\non the anisotropic silver (110) surface. This crucial step in the silicene gold\nrush could give a new kick to silicon on the electronics road-map and opens the\nmost promising route towards wide-ranging applications. A hint of\nsuperconductivity in these silicene stripes poses intriguing questions related\nto the delicate interplay between paired correlated fermions, massless Dirac\nfermions and bosonic quasi-particules in low dimensions.",
        "positive": "Combination effect of growth enhancers and carbon sources on synthesis\n  of single-walled carbon nanotubes from solid carbon growth seeds: In the synthesis of highly crystalline single-walled carbon nanotubes\n(SWCNTs), high growth temperatures are preferred, while the formation of\nimpurity amorphous carbon (a-C) causes the termination of SWCNT growth and\ndegrades its properties. To remove this by-product, H2O and CO2 have been\nemployed in metal-catalyzed SWCNT growth systems because of their oxidizing\nability. Recently, nonmetallic nanoparticles have become one of the growth seed\ncandidates because of their high melting points and fewer metal impurities. In\nthis study, by using nanodiamond-derived carbon nanoparticles as the solid\ngrowth seeds, we investigated the effect of CO2 and H2O on high-temperature\nSWCNT growth with two types of carbon-source supplies: C2H2 and C2H4. In this\ngrowth system, H2O showed oxidizing ability to etch a-C with either carbon\nsources. CO2 exhibited a similar a-C formation-preventing role in C2H4-supplied\ngrowth and achieved higher-purity SWCNTs with higher concentration of C2H4 than\nthe case of H2O. However, in contrast to the other combinations, CO2 injection\nin the C2H2-supplied growth significantly enhanced the formation of a-C rather\nthan the removal of it while the yield of SWCNTs was also increased, indicating\nthe occurrence of the dehydration reaction between CO2 and C2H2. The present\nfindings will lead to efficient growth of high-quality SWCNTs from nonmetallic\ngrowth seeds with the use of growth enhancers."
    },
    {
        "anchor": "Small atoms fall into bulk from non-close-packed surfaces?: Surface rippling has been observed when atoms of $X$ and $A$ are mixed on the\n$A$ substrate surface. The rippling amplitude has been estimated using hard\nsphere models. We present a gedanken experiment predicting a penetration of\nsmall atoms into bulk through the (100) surface. To understand how the\nelectronic effects alter this picture, we investigate the surface rippling of\n$X/A(100)$ from first-principles, assuming $X=$ H to Bi except for noble gases\nand $A=$ Cu, Ag, and Au. We show that the small atoms (such as H, C, N, O and\nF) attract electrons from the substrate due to the large electronegativity,\nwhich prevent them from passing through the void in the (100) surface. The\nbehaviors of small atoms are further explored by studying lateral displacements\nof the top layer in the $A$ substrate and a formation of the $X$ dimer above,\nbelow, and across the top layer. The present work provides an example to\nunderstand when atoms are not hard spheres.",
        "positive": "Optical conductivity enhancement and thermal reduction of BN-codoped MgO\n  nanosheet: Significant effects of B-N atomic interaction: We investigate the electronic, the thermal, and the optical properties of\nBN-codoped MgO monolayers taking into account the interaction effects between\nthe B and the N dopant atoms. The relatively wide indirect band gap of a pure\nMgO nanosheet can be changed to a narrow direct band gap by tuning the B-N\nattractive interaction. The band gap reduction does not only enhance the\noptical properties, including the absorption spectra and the optical\nconductivity, but also the most intense peak is shifted from the Deep-UV to the\nvisible light region. The red shifting of the absorption spectra and the\noptical conductivity are caused by the attractive interaction. In addition,\nboth isotropic and anisotropic characteristics are seen in the optical\nproperties depending on the strength of the B-N attractive interaction. The\nheat capacity is reduced for the BN-doped MgO monolayer, which can be referred\nto changes in the bond dissociation energy. The bond dissociation energy\ndecreases as the difference in the electronegativities of the bonded atoms\ndecreases. The lower difference in the electronegativities leads to a weaker\nendothermic process resulting in reduction of the heat capacity. An ab initio\nmolecular dynamics, AIMD, calculation is utilized to check the thermodynamic\nstability of the pure and the BN-codoped MgO monolayers. We thus confirm that\nthe BN-codopant atoms can be used to gain control of the properties of MgO\nmonolayers for thermo- and opto-electronic devices."
    },
    {
        "anchor": "Impurity-induced states on the surface of 3D topological insulators: We calculate the modification of the local electronic structure caused by a\nlocal impurity on the surface of a 3D Topological Insulator. We find that the\nLDOS around the Dirac point of the electronic spectrum at the surface is\nsignificantly disrupted near the impurity by the creation of low-energy\nresonance state(s) -- however, this is not sufficient to (locally) destroy the\nDirac point. We also calculate the non-trivial spin textures created near the\nmagnetic impurities and discover anisotropic RKKY coupling between them.",
        "positive": "Thermodynamics of interacting single-domain superparamagnetic\n  nanoparticles frozen in the nodes of a regular cubic lattice: In this work, we study the effect of dipole-dipole interparticle interactions\non the static thermodynamic and magnetic properties of an ensemble of\nimmobilized monodisperse superparamagnetic nanoparticles. We assume that\nmagnetic nanoparticles are embedded in the nodes of a regular cubic lattice, so\nthat the particle translational degrees of freedom are turned off. The\nrelaxation of the magnetic moments of the nanoparticles occurs by the Neel\nmechanism. The easy axes are aligned (i) parallel or (ii) perpendicular to the\ndirection of an external field. These models are investigated using theory and\ncomputer simulation, taking microscopic discrete structure explicitly into\naccount. The analytical expressions of the Helmholtz free energy, the static\nmagnetization, and the initial magnetic susceptibility are derived for both\nconfigurations (i) and (ii) as functions of the height of the magnetic\ncrystallographic anisotropy energy barrier, measured by parameter $\\sigma$, and\nthe intensity of the dipole-dipole interparticle interactions measured by\n$\\lambda_e$. A good agreement between the theory and the results of MC\nsimulations in the region of low and moderate values of $\\lambda_e$ and\n$\\sigma$ is obtained. For high values of $\\lambda_e$ and $\\sigma$, the\nstructuring of magnetic moments in regularly orientated structures was found\nfrom MC simulations for configuration (i)."
    },
    {
        "anchor": "Nanoparticle networks as chemoselective sensing devices: We theoretically analyzed transport properties of a molecular network\nconstructed of gold nanoparticles linked with oligophenylenevinulene (OPV)\nmolecules. We showed that the conductance of such system was strongly reduced\nwhen trinitrotoluene (TNT) became attached to the OPV linkers in the network.\nThe reported results are based on the ab inicio electronic structure\ncalculations. These results corroborate and elucidate experiments which\nrevealed significant drops in the conductance the network while the latter was\nexposed to TNT vapors. The results suggest that the detected sensitivity of\ntransport characteristics of the considered nanoparticle network to TNT may be\nused to design a sensing nanodevice.",
        "positive": "Ultrathin BaTiO3 templates for multiferroic nanostructures: Structural, electronic and dielectric properties of high-quality ultrathin\nBaTiO3 films are investigated. The films, which are grown by ozone-assisted\nmolecular beam epitaxy on Nb-doped SrTiO3 (001) substrates and having\nthicknesses as thin 8 unit cells (3.2 nm), are unreconstructed and atomically\nsmooth with large crystalline terraces. A strain-driven transition to 3D island\nformation is observed for films of of 13 unit cells thickness (5.2 nm). The\nhigh structural quality of the surfaces, together with the dielectric\nproperties similar to bulk BaTiO3 and dominantly TiO2 surface termination, make\nthese films suitable templates for the synthesis of high-quality metal-oxide\nmultiferroic heterostructures for the fundamental study and exploitation of\nmagneto-electric effects, such as a recently proposed interface effect in\nFe/BaTiO3 heterostructures based on Fe-Ti interface bonds."
    },
    {
        "anchor": "Hard Magnetic Topological Semimetals in XPt3: Harmony of Berry Curvature: Topological magnetic semimetals, like Co3Sn2S2 and Co2MnGa, are known to\ndisplay exotic transport properties, such as large intrinsic anomalous (AHE)\ndue to uncompensated Berry curvature. The highly symmetric XPt3 compounds\ndisplay anti-crossing gapped nodal lines, which are a driving mechanism in the\nintrinsic Berry curvature Hall effects. Uniquely, these compounds contain two\nsets of gapped nodal lines that harmoniously dominate the Berry curvature in\nthis complex multiband system. We calculate a maximum AHE of 1965 S/cm in the\nCrPt3 by a state-of-the-art first principle electronic structure. We have grown\nhigh-quality thin films by magnetron sputtering and measured a robust AHE of\n1750 S/cm for different sputtering growth conditions. Additionally, the cubic\nfilms display a hard magnetic axis along [111] direction. The facile and\nscalable fabrication of these materials is prime candidates for integration\ninto topological devices.",
        "positive": "Quantum Monte Carlo for minerals at high pressure: Phase stability,\n  equations of state, and elasticity of silica: Silica is an abundant component of the Earth whose crystalline polymorphs\nplay key roles in its structure and dynamics. As the simplest silicates,\nunderstanding pure silica is a prerequisite to understanding the rocky part of\nthe Earth, its majority. First principle density functional theory (DFT)\nmethods have often been used to accurately predict properties of silicates.\nHere, we study silica with quantum Monte Carlo (QMC), which until now was not\ncomputationally possible for such complex materials, and find that QMC\novercomes the failures of DFT. QMC is a benchmark method that does not rely on\ndensity functionals, but rather explicitly treats the electrons and their\ninteractions via a stochastic solution of Schrodinger's equation. Using ground\nstate QMC plus phonons within the quasiharmonic approximation from density\nfunctional perturbation theory, we obtain the thermal pressure and equations of\nstate of silica phases up to Earth's core-mantle boundary. Our results provide\nthe most well-constrained equations of state and phase boundaries available for\nsilica. QMC indicates a transition to the most dense alpha-PbO2 structure above\nthe core-insulating D\" layer, suggesting the absence of significant free silica\nin the bulk lower mantle, which has been assumed but never proven. We also find\nan accurate shear elastic constant and its geophysically important softening\nwith pressure."
    },
    {
        "anchor": "Diffuse scattering in metallic tin polymorphs: The lattice dynamics of the metallic tin {\\beta} and {\\gamma} polymorphs has\nbeen studied by a combination of diffuse scattering, inelastic x-ray scattering\nand density functional perturbation theory. The non-symmorphic space group of\nthe {\\beta}-tin structure results in unusual asymmetry of thermal diffuse\nscattering. Strong resemblance of the diffuse scattering intensity distribution\nin {\\beta} and {\\gamma}-tin were observed, reflecting the structural\nrelationship between the two phases and revealing the qualitative similarity of\nthe underlying electronic potential. The strong influence of the electron\nsubsystem on inter-ionic interactions creates anomalies in the phonon\ndispersion relations. All observed features are described in great detail by\ndensity functional perturbation theory for both {\\beta}- and {\\gamma}-tin at\narbitrary momentum transfers. The combined approach delivers thus a complete\npicture of the lattice dynamics in harmonic description.",
        "positive": "Evidence of itinerant holes for long-range magnetic order in tungsten\n  diselenide semiconductor with vanadium dopants: One primary concern in diluted magnetic semiconductors (DMSs) is how to\nestablish a long-range magnetic order with a low magnetic doping concentration\nto maintain the gate tunability of the host semiconductor, as well as to\nincrease Curie temperature. Two-dimensional van der Waals semiconductors have\nbeen recently investigated to demonstrate the magnetic order in DMSs; however,\na comprehensive understanding of the mechanism responsible for the gate-tunable\nlong-range magnetic order in DMSs has not been achieved yet. Here, we introduce\na monolayer tungsten diselenide (WSe2) semiconductor with V dopants to\ndemonstrate the long-range magnetic order through itinerant spin-polarized\nholes. The V atoms are sparsely located in the host lattice by substituting W\natoms, which is confirmed by scanning tunneling microscopy and high-resolution\ntransmission electron microscopy. The V impurity states and the valence band\nedge states are overlapped, which is congruent with density functional theory\ncalculations. The field-effect transistor characteristics reveal the itinerant\nholes within the hybridized band; this clearly resembles the Zener model. Our\nstudy gives an insight into the mechanism of the long-range magnetic order in\nV-doped WSe2, which can also be used for other magnetically doped\nsemiconducting transition metal dichalcogenides."
    },
    {
        "anchor": "Conformal Three-Dimensional Interphase of Li Metal Anode Revealed by Low\n  Dose Cryo-Electron Microscopy: Using cryogenic transmission electron microscopy, we revealed three\ndimensional (3D) structural details of the electrochemically plated lithium\n(Li) flakes and their solid electrolyte interphase (SEI), including the\ncomposite SEI skin-layer and SEI fossil pieces buried inside the Li matrix. As\nthe SEI skin-layer is largely comprised of nanocrystalline LiF and Li2O in\namorphous polymeric matrix, when complete Li stripping occurs, the compromised\nSEI three-dimensional framework buckles, forming nanoscale bends and wrinkles.\nWe showed that the flexibility and resilience of the SEI skin-layer plays a\nvital role in preserving an intact SEI 3D framework after Li stripping. The\nintact SEI network enables the nucleation and growth of the newly plated Li\ninside the previously formed SEI network in the subsequent cycles, preventing\nadditional large amount of SEI formation between newly plated Li metal and the\nelectrolyte. In addition, cells cycled under the accurately controlled uniaxial\npressure can further enhance the repeated utilization of the SEI framework and\nimprove the coulombic efficiency (CE) by up to 97%, demonstrating an effective\nstrategy of reducing the formation of additional SEI and inactive dead Li. The\nidentification of such flexible and porous 3D SEI framework clarifies the\nworking mechanism of SEI in lithium metal anode for batteries. The insights\nprovided in this work will inspire researchers to design more functional\nartificial 3D SEI on other metal anodes to improve rechargeable metal battery\nwith long cycle life.",
        "positive": "Nanopore-patterned CuSe drives the realization of PbSe-CuSe lateral\n  heterostructure: Monolayer PbSe has been predicted to be a two-dimensional (2D) topological\ncrystalline insulator (TCI) with crystalline symmetry-protected Dirac-cone-like\nedge states. Recently, few-layered epitaxial PbSe has been grown on the SrTiO3\nsubstrate successfully, but the corresponding signature of the TCI was only\nobserved for films not thinner than seven monolayers, largely due to\ninterfacial strain. Here, we demonstrate a two-step method based on molecular\nbeam epitaxy for the growth of the PbSe-CuSe lateral heterostructure on the\nCu(111) substrate, in which we observe a nanopore patterned CuSe layer that\nacts as the template for lateral epitaxial growth of PbSe. This further results\nin a monolayer PbSe-CuSe lateral heterostructure with an atomically sharp\ninterface. Scanning tunneling microscopy and spectroscopy measurements reveal a\nfour-fold symmetric square lattice of such monolayer PbSe with a quasi-particle\nband gap of 1.8 eV, a value highly comparable with the theoretical value of\nfreestanding PbSe. The weak monolayer-substrate interaction is further\nsupported by both density functional theory (DFT) and projected crystal orbital\nHamilton population, with the former predicting the monolayer's anti-bond state\nto reside below the Fermi level. Our work demonstrates a practical strategy to\nfabricate a high-quality in-plane heterostructure, involving a monolayer TCI,\nwhich is viable for further exploration of the topology-derived quantum physics\nand phenomena in the monolayer limit."
    },
    {
        "anchor": "Identifying structural order in Selenium with Near-Edge Spectroscopy: We investigate the crystallization of amorphous arsenic-selenium alloys with\n0%, 0.5%, 2%, 6%, 10%, and 19% arsenic by atomic concentration using\nsynchrotron X-ray absorption spectroscopy. We identify crystalline order using\nthe extended X-ray absorption fine structure (EXAFS) spectra and correlate this\norder to changes in features of the X-ray absorption near edge structure\n(XANES) spectra. We find supporting evidence that the structure of amorphous\nselenium is composed of disordered helical chains, and is therefore closer to\nthe trigonal crystalline phase than the monoclinic crystalline phase.",
        "positive": "Solute hydrogen and deuterium observed at the near atomic scale in\n  high-strength steel: Observing solute hydrogen (H) in matter is a formidable challenge, yet,\nenabling quantitative imaging of H at the atomic-scale is critical to\nunderstand its deleterious influence on the mechanical strength of many\nmetallic alloys that has resulted in many catastrophic failures of engineering\nparts and structures. Here, we report on the APT analysis of hydrogen (H) and\ndeuterium (D) within the nanostructure of an ultra-high strength steel with\nhigh resistance to hydrogen embrittlement. Cold drawn, severely deformed\npearlitic steel wires (Fe-0.98C-0.31Mn-0.20Si-0.20Cr-0.01Cu-0.006P-0.007S wt.%,\n{\\epsilon}=3.1) contains cementite decomposed during the pre-deformation of the\nalloy and ferrite. We find H and D within the decomposed cementite, and at some\ninterfaces with the surrounding ferrite. To ascertain the origin of the H/D\nsignal obtained in APT, we explored a series of experimental workflows\nincluding cryogenic specimen preparation and cryogenic-vacuum transfer from the\npreparation into a state-of-the-art atom probe. Our study points to the\ncritical role of the preparation, i.e. the possible saturation of H-trapping\nsites during electrochemical polishing, how these can be alleviated by the use\nof an outgassing treatment, cryogenic preparation and transfer prior to\ncharging. Accommodation of large amounts of H in the under-stoichiometric\ncarbide likely explains the resistance of pearlite against hydrogen\nembrittlement."
    },
    {
        "anchor": "On the interface polaron formation in organic field-effect transistors: A model describing the low density carrier state in an organic single crystal\nFET with high-$\\kappa$ gate dielectrics is studied. The interplay between\ncharge carrier coupling with inter-molecular vibrations in the bulk of the\norganic material and the long-range interaction induced at the interface with a\npolar dielectric is investigated. This interplay is responsible for the\nstabilization of a polaronic state with an internal structure extending on few\nlattice sites, at much lower coupling strengths than expected from the polar\ninteraction alone. This effect could give rise to polaron self-trapping in\nhigh-$\\kappa$ organic FET's without invoking unphysically large values of the\ncarrier interface interaction.",
        "positive": "Surface morphology and magnetic anisotropy in (Ga,Mn)As: Atomic Force Microscopy and Grazing incidence X-ray diffraction measurements\nhave revealed the presence of ripples aligned along the $[1\\bar{1}0]$ direction\non the surface of (Ga,Mn)As layers grown on GaAs(001) substrates and buffer\nlayers, with periodicity of about 50 nm in all samples that have been studied.\nThese samples show the strong symmetry breaking uniaxial magnetic anisotropy\nnormally observed in such materials. We observe a clear correlation between the\namplitude of the surface ripples and the strength of the uniaxial magnetic\nanisotropy component suggesting that these ripples might be the source of such\nanisotropy."
    },
    {
        "anchor": "Fermi-liquid and Fermi surface geometry effects in propagation of low\n  frequency electromagnetic waves through thin metal films: In the present work we theoretically analyze the contribution from a\ntransverse Fermi-liquid collective mode to the transmission of electromagnetic\nwaves through a thin film of a clean metal in the presence of a strong external\nmagnetic field. We show that at the appropriate Fermi surface geometry the\ntransverse Fermi-liquid wave may appear in conduction electrons liquid at\nfrequencies $\\omega$ significantly smaller than the cyclotron frequency of\ncharge carriers $\\Omega$ provided that the mean collision frequency $\\tau^{-1}$\nis smaller than $\\omega.$ Also, we show that in realistic metals size\noscillations in the transmission coefficient associated with the Firmi-liquid\nmode may be observable in experiments. Under certain conditions these\noscillations may predominate over the remaining size effects in the\ntransmission coefficient.",
        "positive": "Charge Transport in Mixed Metal Halide Perovskite Semiconductors: Investigation of the inherent field-driven charge transport behaviour of 3D\nlead halide perovskites has largely remained a challenging task, owing\nprimarily to undesirable ionic migration effects near room temperature. In\naddition, the presence of methylammonium in many high performing 3D perovskite\ncompositions introduces additional instabilities, which limit reliable room\ntemperature optoelectronic device operation. Here, we address both these\nchallenges and demonstrate that field-effect transistors (FETs) based on\nmethylammonium-free, mixed-metal (Pb/Sn) perovskite compositions, that are\nwidely studied for solar cell and light-emitting diode applications, do not\nsuffer from ion migration effects as their pure Pb counterparts and reliably\nexhibit hysteresis free p-type transport with high mobility reaching 5.4\n$cm^2/Vs$, ON/OFF ratio approaching $10^6$, and normalized channel conductance\nof 3 S/m. The reduced ion migration is also manifested in an activated\ntemperature dependence of the field-effect mobility with low activation energy,\nwhich reflects a significant density of shallow electronic defects. We\nvisualize the suppressed in-plane ionic migration in Sn-containing perovskites\ncompared to their pure-Pb counterparts using photoluminescence microscopy under\nbias and demonstrate promising voltage and current-stress device operational\nstabilities. Our work establishes FETs as an excellent platform for providing\nfundamental insights into the doping, defect and charge transport physics of\nmixed-metal halide perovskite semiconductors to advance their applications in\noptoelectronic devices."
    },
    {
        "anchor": "Huge out-of-plane piezoelectric response in ferromagnetic monolayer\n  NiClI: The combination of piezoelectricity and ferromagnetic (FM) order in a\ntwo-dimensional (2D) material, namely 2D piezoelectric ferromagnetism (PFM),\nmay open up unprecedented opportunities for novel device applications. Here, we\npredict an in-plane FM semiconductor Janus monolayer NiClI with considerably\nlarge magnetic anisotropy energy (MAE) of 1.439 meV, exhibiting dynamic,\nmechanical and thermal stabilities. The NiClI monolayer possesses larger\nin-plane piezoelectricity ($d_{11}$$=$5.21 pm/V) comparable to that of\n$\\mathrm{MoS_2}$. Furthermore, NiClI has huge out-of-plane piezoelectricity\n($d_{31}$$=$1.89 pm/V), which is highly desirable for ultrathin piezoelectric\ndevice application. It is proved that huge out-of-plane piezoelectricity is\nrobust against electronic correlation, which confirms reliability of huge\n$d_{31}$. Finally, being analogous to NiClI, PFM with large out-of-plane\npiezoelectricity can also be achieved in the Janus monolayers of NiClBr and\nNiBrI, with the predicted $d_{31}$ of 0.73 pm/V and 1.15 pm/V, respectively.\nThe predicted huge out-of-plane piezoelectric response makes Janus monolayer\nNiClI a good platform for multifunctional semiconductor spintronic\napplications, which is also compatible with the bottom/top gate technologies of\nconventional semiconductor nanoelectronic devices.",
        "positive": "Electrical and Thermal transport studies of Sr and Mn co-substituted\n  NdCoO3: Oxide thermoelectrics are exciting due to their chemical and thermal\nstability at high temperatures. However, the efficacy of these materials are\nlimited by poor figure of merit (zT). In this study, the role of Sr and Mn\nco-substitution on the thermoelectric properties of NdCoO3\n(Nd_{1-x}Sr_xCo_{1-y}Mn_yO_3; 0.00 \\leq x \\leq 0.10; 0.00 \\leq y \\leq 0.10) is\ninvestigated. The Seebeck coefficient decreases with single Sr substitution at\nNd site; however, the Sr and Mn co-substitution enhances the Seebeck\ncoefficient compared to single Sr substitution and is attributed to the\nlocalization effect. Sr substitution at La site creates hole in the system and\nresults in enhanced electrical conductivity ({\\sigma}); however, {\\sigma}\nreduces with Mn substitution at Co site in NdCoO_3. A reduced thermal\nconductivity for the co-substituted samples is observed and attributed to\ndecrease in phonon thermal conductivity. Simultaneous optimization of TE\nparameters results in improved zT \\sim 0.038 for\nNd_{0.95}Sr_{0.05}Co_{0.95}Mn_{0.05}O_3 at 540 K."
    },
    {
        "anchor": "Large spin gaps in half metals MN4 (M=Mn, Fe, Co) with N2 dimers: We predict that cubic MN4 (M=Mn, Fe, Co) are all half metals with the largest\nspin gap up to ~ 5 eV. They possess robust ferromagnetic ground states with the\nhighest Curie temperature up to ~ 103 K. Our calculations indicate these\ncompounds are energetically favored, dynamically and mechanically stable. It is\nproposed that self-doping of these 3d transition metals occurs in MN4 due to\nthe reduction in electronegativity of N2 dimers. This model can well explain\nthe calculated integer magnetic moments, large spin gaps of MN4 and\nsemiconducting behavior for NiN4 as well. Our results highlight the difference\nin electronegativity between transition metal ions and non-metal entities in\nforming half metals and the role of N2 dimer in enlarging the spin gaps for\nnitride half metals.",
        "positive": "Single-Crystal N-polar GaN p-n Diodes by Plasma-Assisted Molecular Beam\n  Epitaxy: N-polar GaN p-n diodes are realized on single-crystal N-polar GaN bulk wafers\nby plasma-assisted molecular beam epitaxy growth. The current-voltage\ncharacteristics show high-quality rectification and electroluminescence\ncharacteristics with a high on/off current ratio and interband photon emission.\nThe measured electroluminescence spectrum is dominated by strong near-band edge\nemission, while deep level luminescence is greatly suppressed. A very low\ndislocation density leads to a high reverse breakdown electric field. The low\nleakage current N-polar diodes open up several potential applications in\npolarization-engineered photonic and electronic devices."
    },
    {
        "anchor": "First-principles analysis of the efficiency of photovoltaic layers for\n  CuAu-like chalcogenides and silicon: Chalcopyrite semiconductors are of considerable interest for application as\nabsorber layers in thin-film photovoltaic cells. When growing films of these\ncompounds, however, they are often found to contain CuAu- like domains, a\nmetastable phase of chalcopyrite. It has been reported that for CuInS2, the\npresence of the CuAu-like phase improves the short circuit current of the\nchalcopyrite-based photovoltaic cell. We investigate the thermodynamic\nstability of both phases for a selected list of I-III-VI2 materials using a\nfirst-principles density functional theory approach. For the CuIn-VI2\ncompounds, the difference in formation energy between the chalcopyrite and\nCuAu-like phase is found to be close to 2 meV/atom, indicating a high\nlikelihood of the presence of CuAu-like domains. Next, we calculate the\nSpectroscopic Limited Maximum Efficiency (SLME) of the CuAu- like phase and\ncompare the results with those of the corresponding chalcopyrite phase. We\nidentify several candidates with a high efficiency, such as CuAu-like CuInS2,\nfor which we obtain an SLME of 29% at a thickness of 500 nm. We observe that\nthe SLME can have values above the Shockley-Queisser (SQ) limit, and show that\nthis can occur because the SQ limit assumes the absorptivity to be a step\nfunction, thus overestimating the radiative recombination in the detailed\nbalance approach. This means that it is possible to find higher theoretical\nefficiencies within this framework simply by calculating the J-V characteristic\nwith an absorption spectrum. Finally, we expand our SLME analysis to indirect\nband gap absorbers by studying silicon, and find that the SLME quickly\noverestimates the reverse saturation current of indirect band gap materials,\ndrastically lowering their calculated efficiency.",
        "positive": "Electrosynthetic control of CNT conductivity & morphology: Scale-up of\n  the transformation of the greenhouse gas CO2 into carbon nanotubes by molten\n  carbonate electrolysis: Transformation of carbon dioxide into carbon nanotubes, CNTs, by electrolysis\nin molten carbonates provides a low cost route to extract and store this\ngreenhouse gas. CNTs are more stable, compact and valuable than fuels or other\nCO2 conversion products, providing an incentive to remove CO2 for climate\nmitigation. Previously, solid core carbon nanofibers, CNFs were formed with\nC-13 isotope CO2, whereas hollow core fibers - carbon nanotubes, CNTs, were\nformed with natural isotope CO2 splitting in molten lithium carbonate. Here we\ndemonstrate the extraordinary range of specific morphologies and conductivities\nof CNTs that can be achieved through control of the electrolysis conditions in\na one pot-synthesis, and scale-up of this process by which the greenhouse gas\nCO2 is transformed into carbon nanotubes by molten carbonate electrolysis.\nAddition of Li2BO3, boron dopes and greatly enhances CNT conductivity formed at\nthe galvanized steel cathode. Addition of CaCO3 to the Li2CO3 electrolyte,\ndecreases oxide solubility in the region of CNT growth, producing straight\nthin-walled CNTs."
    },
    {
        "anchor": "Theory of resonant Raman scattering due to spin-flips of resident charge\n  carries and excitons in perovskite semiconductors: We have developed a theory of Raman scattering with single and double spin\nflips of localized resident electrons and holes as well as nonequilibrium\nlocalized excitons in semiconductor perovskite crystals under optical\nexcitation in the resonant exciton region. Scattering mechanisms involving\nlocalized excitons, biexcitons and exciton polaritons as intermediate states\nhas been examined, the spin-flip Raman scattering by polaritons being a novel\nmechanism. The derived equations are presented in the invariant form allowing\none for the analysis of the dependence of scattering efficiency on the\npolarization of the initial and scattered light and on the orientation of the\nexternal magnetic field.",
        "positive": "Power-law decay in first-order relaxation processes: Starting from a simple definition of stationary regime in first-order\nrelaxation processes, we obtain that experimental results are to be fitted to a\npower-law when approaching the stationary limit. On the basis of this result we\npropose a graphical representation that allows the discrimination between\npower-law and stretched exponential time decays. Examples of fittings of\nmagnetic, dielectric and simulated relaxation data support the results."
    },
    {
        "anchor": "Spin diffusion and injection in semiconductor structures: Electric field\n  effects: In semiconductor spintronic devices, the semiconductor is usually lightly\ndoped and nondegenerate, and moderate electric fields can dominate the carrier\nmotion. We recently derived a drift-diffusion equation for spin polarization in\nthe semiconductors by consistently taking into account electric-field effects\nand nondegenerate electron statistics and identified a high-field diffusive\nregime which has no analogue in metals. Here spin injection from a ferromagnet\n(FM) into a nonmagnetic semiconductor (NS) is extensively studied by applying\nthis spin drift-diffusion equation to several typical injection structures such\nas FM/NS, FM/NS/FM, and FM/NS/NS structures. We find that in the high-field\nregime spin injection from a ferromagnet into a semiconductor is enhanced by\nseveral orders of magnitude. For injection structures with interfacial\nbarriers, the electric field further enhances spin injection considerably. In\nFM/NS/FM structures high electric fields destroy the symmetry between the two\nmagnets at low fields, where both magnets are equally important for spin\ninjection, and spin injection becomes locally determined by the magnet from\nwhich carriers flow into the semiconductor. The field-induced spin injection\nenhancement should also be insensitive to the presence of a highly doped\nnonmagnetic semiconductor (NS$^+$) at the FM interface, thus FM/NS$^+$/NS\nstructures should also manifest efficient spin injection at high fields.\nFurthermore, high fields substantially reduce the magnetoresistance observable\nin a recent experiment on spin injection from magnetic semiconductors.",
        "positive": "Computer simulations of ionic liquids at electrochemical interfaces: Ionic liquids are widely used as electrolytes in electrochemical devices. In\nthis context, many experimental and theoretical approaches have been recently\ndeveloped for characterizing their interface with electrodes. In this\nperspective article, we review the most recent advances in the field of\ncomputer simulations (mainly molecular dynamics). A methodology for simulating\nelectrodes at constant electrical potential is presented. Several types of\nelectrode geometries have been investigated by many groups in order to model\nplanar, corrugated and porous materials and we summarize the results obtained\nin terms of the structure of the liquids. This structure governs the quantity\nof charge which can be stored at the surface of the electrode for a given\napplied potential, which is the relevant quantity for the highly topical use of\nionic liquids in supercapacitors (also known as electrochemical double-layer\ncapacitors). A key feature, which was also shown by atomic force microscopy and\nsurface force apparatus experiments, is the formation of a layered structure\nfor all ionic liquids at the surface of planar electrodes. This organization\ncannot take place inside nanoporous electrodes, which results in a much better\nperformance for the latter in supercapacitors. The agreement between\nsimulations and electrochemical experiments remains qualitative only though,\nand we outline future directions which should enhance the predictive power of\ncomputer simulations. In the longer term, atomistic simulations will also be\napplied to the case of electron transfer reactions at the interface, enabling\nthe application to a broader area of problems in electrochemistry, and the few\nrecent works in this field are also commented upon."
    },
    {
        "anchor": "Optical properties of CsCu$_2$X$_3$ (X=Cl, Br and I): A comparative\n  study between hybrid time-dependent density-functional theory and the\n  Bethe-Salpeter equation: The cesium copper halides CsCu$_2$X$_3$ (X=Cl, Br and I) are a class of\nall-inorganic perovskites with interesting and potentially useful optical\nproperties, characterized by distinct excitonic features. We present a\ncomputational study of the optical absorption spectra of CsCu$_2$X$_3$,\ncomparing time-dependent density-functional theory (TDDFT) and the\nBethe-Salpeter equation (BSE), using $GW$ quasiparticle band structures as\ninput. The TDDFT calculations are carried out using several types of global\nhybrid exchange-correlation functionals. It is found that an admixture of\nnonlocal exchange determined by the dielectric constant produces optical\nspectra in excellent agreement with the BSE. Thus, hybrid TDDFT emerges as a\npromising first-principles approach for excitonic effects in solids.",
        "positive": "Magnetic Compton profiles of disordered Fe$_{0.5}$Ni$_{0.5}$ and ordered\n  FeNi alloys: We study the magnetic Compton profile (MCP) of the disordered\nFe$_{0.5}$Ni$_{0.5}$ and of the ordered FeNi alloys and discuss the interplay\nbetween structural disorder and electronic correlations. The Coherent Potential\nApproximation is employed to model the substitutional disorder within the\nsingle-site approximation, while local electronic correlations are captured\nwith the Dynamical Mean Field Theory. Comparison with the experimental data\nreveals the limitation of local spin-density approximation in low momentum\nregion, where we show that including local but dynamic correlations the\nexperimental spectra is excellently described. We further show that using local\nspin-density approximation no significant difference is seen between the MCP\nspectra of the disordered Fe$_{0.5}$Ni$_{0.5}$ and a hypothetical, ordered FeNi\nalloy with a simple cubic unit cell. Only by including the electronic\ncorrelations, the spectra significantly separate, from the second Brillouin\nzone boundary down to zero momenta. The difference between the MCP spectra of\nordered and disordered alloys is discussed also in terms of the atomic-type\ndecompositions. Finally based on the presented calculations we predict the\nshape of the MCP profile for the ordered FeNi alloy along the [111] direction."
    },
    {
        "anchor": "Surface nucleation of the paraelectric phase in ferroelectric BaTiO3:\n  Atomic scale mapping: In ferroelectricity, atomic-scale dipole moments interact collectively to\nproduce strong electro-mechanical coupling and switchable macroscopic\npolarization. Hence, the functionality of ferroelectrics emerges at a\nsolid-solid phase transformation that is accompanied by a sudden disappearance\nof an inversion symmetry. Much effort has been put to understand the\nferroelectric transition at the polarization length scale. Nevertheless, the\ndipole-moment origin of ferroelectricity has remained elusive. Here, we used\nvariable-temperature high-resolution transmission electron microscopy to reveal\nthe dipole-moment dynamics during the ferroelectric-to-paraelectric transition.\nWe show that the transition occurs when paraelectric nuclei of the size of a\ncouple of unit cells emerge near the surface. Upon heating, the cubic phase\nsidewalk grows towards the bulk. We quantified the nucleation barrier and show\ndominancy of mechanical interactions, helping us demonstrate similarities to\npredictions of domain nucleation during electric field switching. Our work\nmotivates dynamic atomic-scale characterizations of solid-solid transitions in\nother materials.",
        "positive": "Magnetic Response of NiFe2O4 nanoparticles in polymer matrix: We report the magnetic properties of magnetic nano-composite, consisting of\ndifferent quantity of NiFe2O4 nanoparticles in polymer matrix. The\nnanoparticles exhibited a typical magnetization blocking, which is sensitive on\nthe variation of magnetic field, mode of zero field cooled/field cooled\nexperiments and particle quantity in the matrix. The samples with lower\nparticle quantity showed an upturn of magnetization down to 5 K, whereas the\nblocking of magnetization dominates at lower temperatures as the particle\nquantity increases in the polymer. We examine such magnetic behaviour in terms\nof the competitive magnetic ordering between core and surface spins of\nnanoparticles, taking into account the effect of inter-particle (dipole-dipole)\ninteractions on nanoparticle magnetic dynamics."
    },
    {
        "anchor": "Modelling of Pyroelectric Response in Inhomogeneous\n  Ferroelectric-Semiconductor Films: We have modified Landau-Khalatnikov approach and shown that the pyroelectric\nresponse of inhomogeneous ferroelectric-semiconductor films can be described by\nusing six coupled equations for six order parameters: average displacement, its\nmean-square fluctuation and correlation with charge defects density\nfluctuations, average pyroelectric coefficient, its fluctuation and correlation\nwith charge defects density fluctuations. Coupled equations demonstrate the\ninhomogeneous reversal of pyroelectric response in contrast to the equations of\nLandau-Khalatnikov type, which describe the homogeneous reversal with the sharp\npyroelectric coefficient peak near the thermodynamic coercive field value.\nWithin the framework of our model pyroelectric hysteresis loop becomes much\nsmoother, thinner and lower as well as pyroelectric coefficient peaks near the\ncoercive field completely disappear under the increase of disordering caused by\ndefects. This effect is similar to the well-known \"square to slim transition\"\nof the ferroelectric hysteresis loops in relaxor ferroelectrics. Also the\nincrease of defect concentration leads to the drastic decrease of the coercive\nfield typical for disordered ferroelectrics. Usually pyroelectric hysteresis\nloops of doped and inhomogeneous ferroelectrics have typical smooth shape\nwithout any pyroelectric coefficient peaks and coercive field values much lower\nthan the thermodynamic one. Therefore our approach qualitatively explains\navailable experimental results. Rather well quantitative agreement between our\nmodelling and typical Pb(Zr,Ti)O3-film pyroelectric and ferroelectric loops has\nbeen obtained.",
        "positive": "Composition-dependent polarization switching behaviors of\n  (111)-preferred polycrystalline Pb(Zr_{x}Ti_{1-x})O_{3} thin films: We investigated the time-dependent polarization switching behaviors of\n(111)-preferred polycrystalline Pb(ZrxTi1-x)O3 thin films with various Zr\nconcentrations. We could explain all the polarization switching behaviors well\nby assuming Lorentzian distributions in the logarithmic polarization switching\ntime [Refer to J. Y. Jo et al., Phys. Rev. Lett. (in press)]. Based on this\nanalysis, we found that the Zr ion-substitution for Ti ions would induce broad\ndistributions in the local field due to defect dipoles, which makes the\nferroelectric domain switching occur more easily."
    },
    {
        "anchor": "Microscopic mechanisms of thermal and driven diffusion of non rigid\n  molecules on surfaces: The motion of molecules on solid surfaces is of interest for technological\napplications such as catalysis and lubrication, but it is also a theoretical\nchallenge at a more fundamental level. The concept of activation barriers is\nvery convenient for the interpretation of experiments and as input for Monte\nCarlo simulations but may become inadequate when mismatch with the substrate\nand molecular vibrations are considered. We study the simplest objects\ndiffusing on a substrate at finite temperature $T$, namely an adatom and a\ndiatomic molecule (dimer), using the Langevin approach. In the driven case, we\nanalyse the characteristic curves, comparing the motion for different values of\nthe intramolecular spacing, both for T=0 and $T\\ne 0$. The mobility of the\ndimer is higher than that of the monomer when the drift velocity is less than\nthe natural stretching frequency. The role of intramolecular excitations is\ncrucial in this respect. In the undriven case, the diffusive dynamics is\nconsidered as a function of temperature. Contrary to atomic diffusion, for the\ndimer it is not possible to define a single, temperature independent,\nactivation barrier. Our results suggest that vibrations can account for drastic\nvariations of the activation barrier. This reveals a complex behaviour\ndetermined by the interplay between vibrations and a temperature dependent\nintramolecular equilibrium length.",
        "positive": "Synthesis of ferroelectric LaWN3 -- the first nitride perovskite: Next generation telecommunication technologies would benefit from strong\npiezoelectric and ferroelectric response in materials that are compatible with\nnitride radio-frequency electronic devices. Ferroelectric oxides with\nperovskite structure have been used in sensors and actuators for half a\ncentury, and halide perovskites transformed photovoltaics research in the past\ndecade, but neither of them is compatible with nitride semiconductors. Nitride\nperovskites, despite numerous computational predictions, have not been\nexperimentally demonstrated and their properties remain unknown. Here we report\nthe experimental realization of the first nitride perovskite: lanthanum\ntungsten nitride (LaWN3). Oxygen-free LaWN3 thin films in a polar perovskite\nstructure are confirmed by spectroscopy, scattering, and microscopy techniques.\nScanning probe measurements confirm a large piezoelectric response and strongly\nsuggest ferroelectric behavior, making it the first stable nitride\nferroelectric compound. These results should lead to integration of LaWN3 with\nnitride semiconductors for wireless telecommunication applications, while\nenabling synthesis of many other predicted nitride perovskites."
    },
    {
        "anchor": "Biphonons in the Klein-Gordon lattice: A numerical approach is proposed for studying the quantum optical modes in\nthe Klein-Gordon lattices where the energy contribution of the atomic\ndisplacements is non-quadratic. The features of the biphonon excitations are\ninvestigated in detail for different non-quadratic contributions to the\nHamiltonian. The results are extended to multi-phonon bound states.",
        "positive": "Ultrafast light-induced Coherent Optical and Acoustic Phonons in few\n  Quintuple Layers of Topological Insulators Bi2Te3: Ultrafast lattice dynamics of few quintuple layers of topological insulator\n(TI) Bi$_2$Te$_3$ is studied with time-resolved optical pump-probe\nspectroscopy. Both optical and acoustic phonons are photogenerated and\ndetected. Here, in order to get new insights on the out-of-equilibrium\nelectron-phonon coupling and phonons dynamics in confined TI, different\nnanostructures have been investigated (single or polycrystalline QLs assemblies\nand nano-crystallized islands). Contrary to previous literature claims, we show\nthat even for nanostructures containing only 10 quintuple layers (QLs), the\nsymmetric A1g(I) coherent optical phonon is efficiently photogenerated and no\nrestriction due to the structural confinement appears. We also observe that\nwhatever the arrangement of the nanostructures, the A1g(I) optical phonon\nfeatures are similar (lifetime). We also report the observation of confined\ncoherent acoustic phonons propagating from QLs to QLs whose spectrum is, this\ntime, very sensitive to the atomic arrangement. In the case of the single\ncrystalline ultrathin film, the time of flight analysis of these acoustic\nphonons provides direct estimate of the elastic properties of these\nnanostructures as well as some estimates of Van der Waals interactions between\nQLs."
    },
    {
        "anchor": "Structural, Elastic and Electronic Properties of $SmFeO_3$ using Density\n  Functional Theory: We perform first principles simulations for the structural, elastic and\nelectronic properties of orthorhombic samarium orthoferrite $SmFeO_3$ within\nthe framework of density functional theory. A number of different density\nfunctionals, such as local density approximation, generalized gradient\napproximation, Hubbard interaction modified functional, modified\nBecke$-$Johnson approximation and Heyd$-$Scuseria$-$Ernzerhof hybrid functional\nhave been used to model the exact electron exchange-correlation. We estimate\nthe energy of the ground state for different magnetic configurations of\n$SmFeO_3$. The crystal structure of $SmFeO_3$ is characterized in terms of the\nlattice parameters, atomic positions, relevant ionic radii, bond lengths and\nbond angles. The stability of the $SmFeO_3$ orthorhombic structure is simulated\nin terms of its elastic properties. For the electronic structure simulations,\nwe provide estimates based on density functionals with varying degrees of\ncomputational complexities in the Jacob's ladder.",
        "positive": "Effect of magnetic field and temperature on the ferroelectric loop in\n  MnWO4: The ferroelectric properties of MnWO4 single crystal have been investigated.\nDespite a relatively low remanent polarization, we show that the sample is\nferroelectric. The shape of the ferroelectric loop of MnWO4 strongly depends on\nmagnetic field and temperature. While its dependence does not directly\ncorrelate with the magnetocapacitance effect before the paraelectric\ntransition, the effect of magnetic field on the ferroelectric polarization loop\nsupports magnetoelectric coupling."
    },
    {
        "anchor": "Improved magnetization in sputtered dysprosium thin films: 50nm thick nanogranular polycrystalline dysprosium thin films have been\nprepared via ultra-high vacuum DC sputtering on SiO2 and Si wafers. The maximum\nin-plane spontaneous magnetization at T = 4K was found to be MS4K = 3.28T for\nsamples deposited on wafers heated to 350C with a Neel point of TN = 173K and a\nferromagnetic transition at TC = 80K, measured via zero field cooled field\ncooled magnetization measurements, close to single crystal values. The slightly\nreduced magnetization is explained in the light of a metastable face centered\ncubic crystal phase which occurred at the seed interface and granularity\nrelated effects, that are still noticeably influential despite an in-plane\nmagnetic easy axis. As deposited samples showed reduced magnetization of MS4K =\n2.26T, however their ferromagnetic transition shifted to a much higher\ntemperature of TC = 172K and the antiferromagnetic phase was completely\nsuppressed probably as a result of strain.",
        "positive": "Ligand-Surface Interactions and Surface Oxidation of Colloidal PbSe\n  Quantum Dots Revealed by Thin-film Positron Annihilation Methods: Positron Two Dimensional Angular Correlation of Annihilation Radiation\n(2D-ACAR) measurements reveal modifications of the electronic structure and\ncomposition at the surfaces of PbSe quantum dots (QDs), deposited as thin\nfilms, produced by various ligands containing either oxygen or nitrogen atoms.\nIn particular, the 2D-ACAR measurements on thin films of colloidal PbSe QDs\ncapped with oleic acid ligands yield an increased intensity in the electron\nmomentum density (EMD) at high momenta compared to PbSe quantum dots capped\nwith oleylamine. Moreover, the EMD of PbSe QDs is strongly affected by the\nsmall ethylediamine ligands, since these molecules lead to small distances\nbetween QDs and favor neck formation between near neighbor QDs, inducing\nelectronic coupling between neighboring QDs. The high sensitivity to the\npresence of oxygen atoms at the surface can be also exploited to monitor the\nsurface oxidation of PbSe QDs upon exposure to air. Our study clearly\ndemonstrates that positron annihilation spectroscopy applied to thin films can\nprobe surface transformations of colloidal semiconductor QDs embedded in\nfunctional layers."
    },
    {
        "anchor": "Steady-state cracking in brittle substrates beneath adherent films:\n  revisited: This is a technical note aiming at the re-examination of the phenomenon of\nthe steady-state cracking in the two-layer system. The method of Suo and\nHutchinson, as introduced in their 1989 paper, is followed. Our solution is\ncompared with the one appearing in that paper for the substrate-to-film\nthickness ratio $\\lambda_0=10$. We obtain results at three $\\lambda_0<10$\nvalues. Combined with the results for $\\lambda_0=10$, the new sets of values\ncover thickness ratios between 1 and 10, sufficient for determining crack\ninitiation and propagation in almost every relevant problem. We present our\nresults in tables (and figures), thus facilitating their implementation and\nuse.",
        "positive": "Photocorrosion-limited maximum efficiency of solar photoelectrochemical\n  water splitting: Photoelectrochemical (PEC) water splitting to generate hydrogen is one of the\nmost studied methods for converting solar energy into clean fuel because of its\nsimplicity and potentially low cost. Despite over 40 years of intensive\nresearch, PEC water splitting remains in its early stages with stable\nefficiencies far less than 10%, a benchmark for commercial applications. Here,\nwe revealed that the desired photocorrosion stability sets a limit of 2.48 eV\n(relative to the normal hydrogen electrode (NHE)) for the highest possible\npotential of the valence band (VB) edge of a photocorrosion-resistant\nsemiconducting photocatalyst. We further demonstrated that such limitation has\na deep root in underlying physics after deducing the relation between energy\nposition of the valence band edge and free-energy for a semiconductor. The\ndisparity between the stability-limited VB potential at 2.48 V and the oxygen\nevolution reaction (OER) potential at 1.23 V vs NHE reduces the maximum STH\nconversion efficiency to approximately 8% for long-term stable single-bandgap\nPEC water splitting cells. Based on this understanding, we suggest that the\nmost promising strategy to overcome this 8% efficiency limit is to decouple the\nrequirements of efficient light harvesting and chemical stability by protecting\nthe active semiconductor photocatalyst surface with a photocorrosion-resistant\noxide coating layer."
    },
    {
        "anchor": "Emergence of pressure-induced metamagnetic-like state in Mn-doped\n  CdGeAs2 chalcopyrite: The effect of hydrostatic pressure on resistivity and magnetic ac\nsusceptibility has been studied in Mn-doped CdGeAs2 room-temperature (RT)\nferromagnetic chalcopyrite with two types of MnAs micro-clusters. The slight\nincrease of temperature by about 30 K in the region between RT and Curie\ntemperature TC causes a significant change in the positions of pressure-induced\nsemiconductor-metal transition and magnetic phase transitions in low pressure\narea. By conducting measurements of the anomalous Hall resistance in the field\nH \\leq 5 kOe, we present experimental evidence for pressure-induced\nmetamagnetic-like state during the paramagnetic phase at pressure P = 5 GPa.",
        "positive": "On the thermodynamics of pseudo-elastic material models to reproduce the\n  Mullins effect: This work focuses on the thermodynamics of pseudo-elastic models which\nrepresent the Mullins effect. Two established models are analyzed\ntheoretically, their thermomechanical properties are derived, and certain\ncritical points are identified. These findings are used to deduce an\nalternative approach to deviate pseudo-elasticity. This is achieved by defining\na suitable free energy which imposes conditions on the stress tensor and the\ndissipation using the Clausius-Duhem inequality. The concept of\npseudo-elasticity is then generalized to extend arbitrary thermomechanical,\neven inelastic, material models to allow for softening effects. Under weak\nassumptions on the softening function the thermomechanical consistency is\nshown."
    },
    {
        "anchor": "A critical study of the elastic properties and stability of Heusler\n  compounds: Cubic Co$_{2}YZ$ compounds with $L2_{1}$ structure: Elastic constants and their derived properties of various cubic Heusler\ncompounds were calculated using first-principles density functional theory. To\nbegin with, Cu$_2$MnAl is used as a case study to explain the interpretation of\nthe basic quantities and compare them with experiments. The main part of the\nwork focuses on Co$_2$-based compounds that are Co$_2$Mn$M$ with the main group\nelements $M=$~Al, Ga, In, Si, Ge, Sn, Pb, Sb, Bi, and Co$_2TM$ with the main\ngroup elements Si or Ge, and the $3d$ transition metals $T=$~Sc, Ti, V, Cr, Mn,\nand Fe. It is found that many properties of Heusler compounds correlate to the\nmass or nuclear charge $Z$ of the main group element.\n  Blackman's and Every's diagrams are used to compare the elastic properties of\nthe materials, whereas Pugh's and Poisson's ratios are used to analyze the\nrelationship between interatomic bonding and physical properties. It is found\nthat the {\\it Pugh's criterion} on brittleness needs to be revised whereas {\\it\nChristensen's criterion} describes the ductile--brittle transition of Heusler\ncompounds very well. The calculated elastic properties give hint on a metallic\nbonding with an intermediate brittleness for the studied Heusler compounds.\n  The universal anisotropy of the stable compounds has values in the range of\n$0.57 <A_U <2.73$. The compounds with higher $A_U$ values are found close to\nthe middle of the transition metal series. In particular, Co$_2$ScAl with\n$A_U=0.01$ is predicted to be an isotropic material that comes closest to an\nideal Cauchy solid as compared to the remaining Co$_2$-based compounds. Apart\nfrom the elastic constants and moduli, the sound velocities, Debye\ntemperatures, and hardness are predicted and discussed for the studied systems.\nThe calculated slowness surfaces for sound waves reflect the degree of\nanisotropy of the compounds.",
        "positive": "Multiple magnetic transitions and magnetocaloric effect in\n  Gd1-xSmxMn2Ge2 compounds: Magnetic and magnetocaloric properties of polycrystalline samples of\nGd1-xSmxMn2Ge2 have been studied. All the compounds except GdMn2Ge2 show\nre-entrant ferromagnetic behavior. Multiple magnetic transitions observed in\nthese compounds are explained on the basis of the temperature dependences of\nthe exchange strengths of the rare earth and Mn sublattices. Magnetocaloric\neffect is found to be positive at the re-entrant ferromagnetic transition,\nwhereas it is negative at the antiferro-ferromagnetic transition. In SmMn2Ge2,\nthe magnetic entropy change associated with the re-entrant transition is found\nto decrease with field, which is attributed to the admixture effect of the\ncrystal field levels. The isothermal magnetic entropy change is found to\ndecrease with increase in Sm concentration."
    },
    {
        "anchor": "Prediction of a Stable Post-Post-Perovskite Structure from First\n  Principles: A novel stable crystallographic structure is discovered in a variety of ABO3,\nABF3 and A2O3 compounds (including materials of geological relevance,\nprototypes of multiferroics, exhibiting strong spin-orbit effects, etc...), via\nthe use of first principles. This novel structure appears under hydrostatic\npressure, and is the first \"post-post-perovskite\" phase to be found. It\nprovides a successful solution to experimental puzzles in important systems,\nand is characterized by one-dimensional chains linked by group of two via\nedge-sharing oxygen/fluorine octahedra. Such unprecedented organization\nautomatically results in anisotropic elastic properties and new magnetic\narrangements. Depending on the system of choice, this post-post-perovskite\nstructure also possesses electronic band gaps ranging from zero to ~ 10 eV\nbeing direct or indirect in nature, which emphasizes its \"universality\" and its\npotential to have striking, e.g., electrical or transport phenomena.",
        "positive": "Low field magnetoelectric effect in Fe substituted Co4Nb2O9: Co4Nb2O9 (CNO) having {\\alpha}-Al2O3 crystal structure with Co chains along\nc-direction shows gigantic magnetoelelctric coupling below antiferromagnetic\nordering temperature of 27 K but above a spin flop field of 1.6 T. We have\ninvestigated structural, magnetic and magnetoelectric properties of Fe\nsubstituted (10% and 20%) samples and compared with the parent one. In fact\nmagnetic and specific heat measurements have revealed an additional magnetic\ntransition below 10 K and presence of short range magnetic ordering above ~ 50\nK in parent as well as in Fe substituted samples. Linear magnetoelelctric and\nferroelectric behaviours are evidenced in the Fe substituted samples where an\nelectric field of 5 kV/m is sufficient to align the dipoles and the\nmagnetoelelctric coupling is ensured for magnetic fields as low as 0.25 T, far\nbelow the spin flop field."
    },
    {
        "anchor": "Atomic Layer Deposition of Cerium Dioxide Film on TiN and Si Substrates:\n  Structural and Chemical Properties: Cerium dioxide (CeO2) thin films were deposited by atomic layer deposition\n(ALD) on both Si and TiN substrates. The ALD growth produces CeO2 cubic\npolycrystalline films on both substrates. However, the films show a\npreferential orientation along <200> crystallographic direction for CeO2/Si or\n<111> for CeO2/TiN. In correspondence, we measure a relative concentration of\nCe3+ equals to 22.0% in CeO2/Si and around 18% in CeO2/TiN, by X-ray\nphotoelectron spectroscopy. Such values indicate the presence of oxygen\nvacancies in the films. Our results extend the knowledge on the structural and\nchemical properties of ALD-deposited CeO2 either on Si or TiN substrates,\nunderlying films differences and similarities, thus contributing to boost the\nuse of CeO2 through ALD deposition as foreseen in a wide number of\napplications.",
        "positive": "Rhombohedral and Turbostratic Boron Nitride Polytypes Investigated by\n  X-ray Absorption Spectroscopy: The electronic structure of rhombohedral sp2 hybridized boron nitride (r-BN)\nis characterized by X-ray absorption near-edge structure spectroscopy.\nMeasurements are performed at the boron and nitrogen K-edges (1s) and\ninterpreted with first-principles density functional theory calculations,\nincluding final state effects by applying a core-hole. We show that it is\npossible to distinguish between different 2D planar polytypes such as\nrhombohedral, twinned rhombohedral, hexagonal and turbostratic BN by the\ndifference in chemical shifts. In particular, the chemical shift at the B\n1s-edge is shown to be significant for the turbostratic polytype. This implies\nthat the band gap can be tuned by a superposition of different polytypes and\nstacking of lattice planes."
    },
    {
        "anchor": "Adsorption structure determination of a large polyaromatic trithiolate\n  on Cu(111): combination of LEED-I(V) and DFT-vdW: The adsorption geometry of 1,3,5-tris(4-mercaptophenyl)benzene (TMB) on\nCu(111) is determined with high precision using two independent methods,\nexperimentally by quantitative low energy electron diffraction (LEED-I(V)) and\ntheoretically by dispersion corrected density functional theory (DFT-vdW).\nStructural refinement using both methods consistently results in similar\nadsorption sites and geometries. Thereby a level of confidence is reached that\nallows deduction of subtle structural details such as molecular deformations or\nrelaxations of copper substrate atoms.",
        "positive": "Electronic Structure Modeling of Electrochemical Reactions at\n  Electrode/Electrolyte Interfaces in Lithium Ion Batteries: We review recent ab initio molecular dynamics studies of\nelectrode/electrolyte interfaces in lithium ion batteries. Our goals are to\nintroduce experimentalists to simulation techniques applicable to models which\nare arguably most faithful to experimental conditions so far, and to emphasize\nto theorists that the inherently interdisciplinary nature of this subject\nrequires bridging the gap between solid and liquid state perspectives. We\nconsider liquid ethylene carbonate (EC) decomposition on lithium intercalated\ngraphite, lithium metal, oxide-coated graphite, and spinel manganese oxide\nsurfaces. These calculations are put in the context of more widely studied\nwater-solid interfaces. Our main themes include kinetically controlled\ntwo-electron-induced reactions, the breaking of a previously much neglected\nchemical bond in EC, and electron tunneling. Future work on modeling batteries\nat atomic lengthscales requires capabilities beyond state-of-the-art, which\nemphasizes that applied battery research can and should drive fundamental\nscience development."
    },
    {
        "anchor": "Spectral Operator Representations: Machine learning in atomistic materials science has grown to become a\npowerful tool, with most approaches focusing on atomic arrangements, typically\ndecomposed into local atomic environments. This approach, while well-suited for\nmachine-learned interatomic potentials, is conceptually at odds with learning\ncomplex intrinsic properties of materials, often driven by spectral properties\ncommonly represented in reciprocal space (e.g., band gaps or mobilities) which\ncannot be readily atomically partitioned. For such applications, methods which\nrepresent the electronic rather than the atomic structure could be more\npromising. In this work, we present a general framework focused on\nelectronic-structure descriptors which take advantage of the natural symmetries\nand inherent interpretability of physical models. Using this framework, we\nformulate two such representations and apply them respectively to measuring the\nsimilarity of carbon nanotubes and barium titanate polymorphs, and to the\ndiscovery of novel transparent conducting materials (TCMs) in the Materials\nCloud 3D database (MC3D). A random forest classifier trained on 1% of the\nmaterials in the MC3D is able to correctly label 76% of entries in database\nwhich meet common screening criteria for promising TCMs.",
        "positive": "Two-speed phase dynamics in Si(111) (7x7)-(1x1) phase transition: We propose a natural two-speed model for the phase dynamics of Si(111)\n7$\\times$7 phase transition to high temperature unreconstructed phase. We\nformulate the phase dynamics by using phase-field method and adaptive mesh\nrefinement. Our simulated results show that a 7$\\times$7 island decays with its\nshape kept unchanged, and its area decay rate is shown to be a constant\nincreasing with its initial area. LEEM experiments concerned are explained,\nwhich confirms that the dimer chains and corner holes are broken first in the\ntransition, and then the stacking fault is remedied slowly. This phase-field\nmethod is a reliable approach to phase dynamics of surface phase transitions."
    },
    {
        "anchor": "Structural, elastic and electronic properties of Ir-based\n  carbides-antiperovskites Ir3MC (M = Ti, Zr, Nb and Ta) as predicted from\n  first-principles calculations: Structural, elastic, electronic properties and the features of inter-atomic\nbonding in hypothetical Ir-based carbides-antiperovskites Ir3MC (M=Ti, Zr, Nb\nand Ta), as predicted from first-principles calculations, have been\ninvestigated for a first time. Their elastic constants, bulk, shear and Young`s\nmoduli, compressibility, Poisson`s ratio, Debye temperature have been\nevaluated, and their stability, character of elastic anisotropy, brittle /\nductile behavior, as well as electronic structure have been explored in\ncomparison with binary carbides MC having NaCl-type structure. Authors hope\nthat the presented results will be useful for future synthesis of these phases,\nas well as for extending the knowledge about the group of antiperovskite-type\npromising materials.",
        "positive": "Electronic structure and magnetism in Ru based perovskites: The magnetic properties of (Ca,Sr)RuO_3 and Sr_2YRuO_6 are studied within the\ncontext of band structure based Stoner theory. LSDA calculations without\nrecourse to strong correlation effects yield the correct magnetic behavior and\norder in all cases. Insulating character of Sr_2YRuO_6 is reproduced. The\ndifferent magnetic states of SrRuO_3 and CaRuO_3 are shown to be due to the\ndifferent structural distortions. CaRuO_3 is found to be on the verge of a\nferromagnetic instability. O p states hybridize strongly with Ru d states in\nall three compounds, and O, through this hybridization plays an unusually large\nrole in the magnetic properties. Transport properties of CaRuO_3 and SrRuO_3\nare analyzed using the calculated Fermiology. Unusually large magnon and\nparamagnon couplings are found, which are consistent with reported measurements\nof the low temperature specific heat and the resistivity coefficient. We also\ndemonstrate how the calculated band structures can be understood in terms of a\nnearest neighbor tight binding model."
    },
    {
        "anchor": "Theory for a dissipative droplet soliton excited by a spin torque\n  nanocontact: A novel type of solitary wave is predicted to form in spin torque oscillators\nwhen the free layer has a sufficiently large perpendicular anisotropy. In this\nstructure, which is a dissipative version of the conservative droplet soliton\noriginally studied in 1977 by Ivanov and Kosevich, spin torque counteracts the\ndamping that would otherwise destroy the mode. Asymptotic methods are used to\nderive conditions on perpendicular anisotropy strength and applied current\nunder which a dissipative droplet can be nucleated and sustained. Numerical\nmethods are used to confirm the stability of the droplet against various\nperturbations that are likely in experiments, including tilting of the applied\nfield, non-zero spin torque asymmetry, and non-trivial Oersted fields. Under\ncertain conditions, the droplet experiences a drift instability in which it\npropagates away from the nanocontact and is then destroyed by damping.",
        "positive": "Using ultrashort optical pulses to couple ferroelectric and\n  ferromagnetic order in an oxide heterostructure: A new approach to all-optical detection and control of the coupling between\nelectric and magnetic order on ultrafast timescales is achieved using\ntime-resolved second harmonic generation (SHG) to study a ferroelectric\n(FE)/ferromagnet (FM) oxide heterostructure. We use femtosecond optical pulses\nto modify the spin alignment in a\nBa$_{0.1}$Sr$_{0.9}$TiO$_{3}$(BSTO)/La$_{0.7}$Ca$_{0.3}$MnO$_{3}$ (LCMO)\nheterostructure and selectively probe the ferroelectric response using SHG. In\nthis heterostructure, the pump pulses photoexcite non-equilibrium\nquasiparticles in LCMO, which rapidly interact with phonons before undergoing\nspin-lattice relaxation on a timescale of tens of picoseconds. This reduces the\nspin-spin interactions in LCMO, applying stress on BSTO through\nmagnetostriction. This then modifies the FE polarization through the\npiezoelectric effect, on a timescale much faster than laser-induced heat\ndiffusion from LCMO to BSTO. We have thus demonstrated an ultrafast indirect\nmagnetoelectric effect in a FE/FM heterostructure mediated through elastic\ncoupling, with a timescale primarily governed by spin-lattice relaxation in the\nFM layer."
    },
    {
        "anchor": "Nanowire Gold Chains: Formation Mechanisms and Conductance: Structural transformations, electronic spectra and ballistic transport in\npulled gold nanowires are investigated with ab initio simulations, and\ncorrelated with recent measurements. Strain-induced yield of an initial\ndouble-strand wire results first in formation of a bent-chain which transforms\nupon further elongation to a linear atomic chain exhibiting dimerized atomic\nconfigurations. These structures are stabilized by directional local bonding\nwith spd-hybridization. The conductance of the initial double-stranded contact\nis close to 2g_0 and it drops sharply to 1g_0 during the transformation to a\nsingle chain, exhibiting subsequently a 1g_0 plateau extending over an\nelongation well above typical Au-Au distances.",
        "positive": "$\\text{Co}_{25}\\text{Fe}_{75}$ Thin Films with Ultralow Total Damping: We measure the dynamic properties of $\\text{Co}_{25}\\text{Fe}_{75}$ thin\nfilms grown by dc magnetron sputtering. Using ferromagnetic resonance\nspectroscopy, we demonstrate an ultralow total damping parameter in the\nout-of-plane configuration of < 0.0013, whereas for the in-plane configuration\nwe find a minimum total damping of < 0.0020. In both cases, we observe low\ninhomogeneous linewidth broadening in macroscopic films. We observe a minimum\nfull-width half-maximum linewidth of 1 mT at 10 GHz resonance frequency for a\n12 nm thick film. We characterize the morphology and structure of these films\nas a function of seed layer combinations and find large variation of the\nqualitative behavior of the in-plane linewidth vs. resonance frequency.\nFinally, we use wavevector-dependent Brillouin light scattering spectroscopy to\ncharacterize the spin-wave dispersion at wave vectors up to 23 $\\mu\n\\text{m}^{-1}$."
    },
    {
        "anchor": "Fluorescence via Reverse Intersystem Crossing from Higher Triplet States\n  in a Bisanthracene Derivative: To elucidate the high external quantum efficiency observed for organic\nlight-emitting diodes using a bisanthracene derivative, BD1, as the emitting\nmolecule, off-diagonal vibronic coupling constants (VCCs) between the excited\nstates of BD1, which govern non-radiative transition rates, were calculated\nemploying time-dependent density functional theory. The VCCs were analysed\nbased on the concept of vibronic coupling density. The VCC calculations suggest\na fluorescence via higher triplets (FvHT) mechanism, which entails the\nconversion of a T$_4$ exciton generated during electrical excitation into an\nS$_2$ exciton via reverse intersystem crossing (RISC); moreover, the S$_2$\nexciton relaxes to a fluorescent S$_1$ exciton because of large vibronic\ncoupling between S$_2$ and S$_1$. This mechanism is valid as long as the\nrelaxation of triplet states higher than T$_1$ to lower states is suppressed.\nThe symmetry-controlled thermally activated delayed fluorescence (SC-TADF) and\ninverted singlet and triplet (iST) structure, which have been proposed in our\nprevious studies, are the special examples of the FvHT mechanism that need high\nmolecular symmetry. However, BD1 achieves the FvHT mechanism in spite of its\nasymmetrical structure. A general condition for the suppression of radiative\nand non-radiative transitions in molecules with pseudo-degenerate electronic\nstructures such as BD1 is discussed. A superordinate concept, fluorescence via\nRISC, which includes TADF, SC-TADF, iST structure, and FvHT is also proposed.",
        "positive": "Electrically tunable polarizer based on two-dimensional orthorhombic\n  ferrovalley materials: The concept of ferrovalley materials has been proposed very recently. The\nexistence of spontaneous valley polarization, resulting from ferromagnetism, in\nsuch hexagonal two-dimensional materials makes nonvolatile valleytronic\napplications realizable. Here, we introduce a new member of ferrovalley family\nwith orthorhombic lattice, i.e. monolayer group-IV monochalcogenides (GIVMs),\nin which the intrinsic valley polarization originates from ferroelectricity,\ninstead of ferromagnetism. Combining the group theory analysis and\nfirst-principles calculations, we demonstrate that, different from the\nvalley-selective circular dichroism in hexagonal lattice, linearly polarized\noptical selectivity for valleys exists in the new type of ferrovalley\nmaterials. On account of the distinctive property, a prototype of electrically\ntunable polarizer is realized. In the ferrovalley-based polarizer, a laser beam\ncan be optionally polarized in x- or y-direction, depending on the ferrovalley\nstate controlled by external electric fields. Such a device can be further\noptimized to emit circularly polarized radiation with specific chirality and to\nrealize the tunability for operating wavelength. Therefore, we show that\ntwo-dimensional orthorhombic ferrovalley materials are the promising candidates\nto provide an advantageous platform to realize the polarizer driven by electric\nmeans, which is of great importance in extending the practical applications of\nvalleytronics."
    },
    {
        "anchor": "Ultrathin Magnesium-based Coating as an Efficient Oxygen Barrier for\n  Superconducting Circuit Materials: Scaling up superconducting quantum circuits based on transmon qubits\nnecessitates substantial enhancements in qubit coherence time. Among the\nmaterials considered for transmon qubits, tantalum (Ta) has emerged as a\npromising candidate, surpassing conventional counterparts in terms of coherence\ntime. However, the presence of an amorphous surface Ta oxide layer introduces\ndielectric loss, ultimately placing a limit on the coherence time. In this\nstudy, we present a novel approach for suppressing the formation of tantalum\noxide using an ultrathin magnesium (Mg) capping layer deposited on top of\ntantalum. Synchrotron-based X-ray photoelectron spectroscopy (XPS) studies\ndemonstrate that oxide is confined to an extremely thin region directly beneath\nthe Mg/Ta interface. Additionally, we demonstrate that the superconducting\nproperties of thin Ta films are improved following the Mg capping, exhibiting\nsharper and higher-temperature transitions to superconductive and magnetically\nordered states. Based on the experimental data and computational modeling, we\nestablish an atomic-scale mechanistic understanding of the role of the capping\nlayer in protecting Ta from oxidation. This work provides valuable insights\ninto the formation mechanism and functionality of surface tantalum oxide, as\nwell as a new materials design principle with the potential to reduce\ndielectric loss in superconducting quantum materials. Ultimately, our findings\npave the way for the realization of large-scale, high-performance quantum\ncomputing systems.",
        "positive": "Impact of capping agent on structural and optical properties of ZnS\n  nanoparticles: Nanocrystalline samples of pristine capped and uncapped zinc sulphide were\nsynthesized via the sol-gel technique. The nanocrystallinity of the samples\nwere confirmed by the X-ray diffraction technique, where size of the particle\nsize decreases with the increasing of mol. concentration (x = 0.00, 0.02, 0.03,\n0.04 Mol). of capping agent sodium dodecyle sulphate. The obtained crystallite\nsizes were found to be in the range 4.6 nm to 2.7 nm respectively. The optical\nband gaps of the samples were estimated by using ultra-violet visible\nspectroscopic techniques and the band gap values were in the range 3.8 eV to\n4.4 eV. All the samples showed quantum confinement behavior compared to bulk\nsample. Fluorescence (FL) spectra showed three emission peaks at the emission\nwavelengths around 434 nm, 520 nm, 545 nm, 628 nm, and 694 nm. The FL\nintensities were proportional to the concentration of capping agent."
    },
    {
        "anchor": "Interatomic Correlations Moments of Atoms in the Two-Dimensional\n  Hexagonal Lattice by Using Morse and Lenard-Jones Potentials: In this work we investigate the interatomic correlation moments in\ntwo-dimensional model of a weakly anharmonic crystal (i.e., not very high\ntemperatures) with hexagonal lattice, using the Correlative Method of\nUnsymmetrized Self-Consistent Field (CUSF). The numerical results are obtained\n(and compared) by using the Morse and Lenard-Jones potentials.",
        "positive": "Multiple-Modes Scanning Probe Microscopy Characterization of Copper\n  doped Zinc Oxide (ZnO:Cu) Thin Films: This paper presents multiple-modes Scanning Probe Microscopy (SPM) studies on\ncharacterize resistance switching (RS), polarization rotation (PO) and surface\npotential changes in copper doped ZnO (ZnO:Cu) thin films. The bipolar RS\nbehavior is confirmed by conductive Atomic Force Microscopy (c-AFM). The PO\nwith almost 180{\\deg} phase angle is confirmed by using the vertical and\nlateral Piezoresponse Force Microscopy (PFM). In addition, it elucidates that\nobvious polarization rotation behavior can be observed in the sample with\nincreasing Cu concentration. Furthermore, correlation of the RS behavior with\nPO behavior has been studied by performing various mode SPM measurements on the\nsame location. The electric field resulted from the opposite polarization\norientation are corresponded to the different resistance states. It is found\nthat the region with the polarization in downward direction has low resistance\nstate (LRS), whereas the region with upward polarization has high resistance\nstate (HRS). In addition, the Piezoresponse Force Spectroscopy (PFS) and\nSwitching Spectroscopy PFM (SS-PFM) measurements further confirm that the\nexistence of the built-in field due to the uncomplemented polarization may\naffect the depletion region and hence contribute to the RS behavior. In\naddition, Kelvin Probe Force Microscopy (KPFM) results show that, when\nZnO-based thin films is subjected to negative and then followed by positive\nsample bias, injection charge limit current is dominated."
    },
    {
        "anchor": "Kohn-Sham potential with discontinuity for band gap materials: We model a Kohn-Sham potential with a discontinuity at integer particle\nnumbers derived from the GLLB approximation of Gritsenko et al. We evaluate the\nKohn-Sham gap and the discontinuity to obtain the quasiparticle gap. This\nallows us to compare the Kohn-Sham gaps to those obtained by accurate many-body\nperturbation theory based optimized potential methods. In addition, the\nresulting quasiparticle band gap is compared to experimental gaps. In the GLLB\nmodel potential, the exchange-correlation hole is modeled using a GGA energy\ndensity and the response of the hole to density variations is evaluated by\nusing the common-denominator approximation and homogeneous electron gas based\nassumptions. In our modification, we have chosen the PBEsol potential as the\nGGA to model the exchange hole, and add a consistent correlation potential. The\nmethod is implemented in the GPAW code, which allows efficient parallelization\nto study large systems. A fair agreement for Kohn-Sham and the quasiparticle\nband gaps with semiconductors and other band gap materials is obtained with a\npotential which is as fast as GGA to calculate.",
        "positive": "First-principles studies of the electronic and magnetic structures and\n  bonding properties of boron subnitride B$_{13}$N$_2$: Rhombohedral B$_{12}$ unit is viewed as a host matrix embedding linear\ntri-atomic arrangements of elements (E) resulting in a relatively large family\nof boron-rich compounds with B$_{12}${E-E-E} generic formulation. The present\nwork focuses on boron subnitride, B$_{13}$N$_2$ that we express in present\ncontext as B$_{12}${N-B-N}. Within well established quantum density functional\ntheory (DFT) a full study of its electronic properties is provided. Also linear\ntriatomic arrangements in view of the existence in simple compounds such as\nsodium azide NaN$_3$, i.e., Na$^I${N-N-N} and calcium cyanamide,\nCa$^{II}${N-C-N}, we devised Sc$^{III}${N-B-N} to establish comparison with\nB$_{12}${N-B-N}. ScBN$_2$ is calculated to be cohesive and possessing N-B-N\nisolated from ScIII with dB-N = 1.33 {\\AA}. In B$_{12}${N-B-N} an elongated\ndB-N=1.43 {\\AA} is identified due to the bonding of N with one of the two B12\nboron substructures, B1 with the formation of \"3B...N-B-N...3B\"-like complex\naccompanied by a magnetic instability. Spin polarized (SP) calculations led to\nthe onset of magnetization on central boron with M=1 $\\mu_B$ in a stable\nhalf-ferromagnetic ground state observed from the electronic density of states\n(DOS). The results are backed with total energy and calculations in both\nnon-spin-polarized (NSP) and spin-polarized stabilizing the latter\nconfiguration over a broad range of volumes from M(V) plots. Further\nillustrative results are given with the charge densities (total and magnetic)\nand electron localization function (ELF)."
    },
    {
        "anchor": "Hidden symmetry and protection of Dirac points on the honeycomb lattice: The honeycomb lattice possesses a novel energy band structure, which is\ncharacterized by two distinct Dirac points in the Brillouin zone, dominating\nmost of the physical properties of the honeycomb structure materials. However,\nup till now, the origin of the Dirac points is unclear yet. Here, we discover a\nhidden symmetry on the honeycomb lattice and prove that the existence of Dirac\npoints is exactly protected by such hidden symmetry. Furthermore, the moving\nand merging of the Dirac points and a quantum phase transition, which have been\ntheoretically predicted and experimentally observed on the honeycomb lattice,\ncan also be perfectly explained by the parameter dependent evolution of the\nhidden symmetry.",
        "positive": "Paraelectric KH$_2$PO$_4$ Nanocrystals in Monolithic Mesoporous Silica:\n  Structure and Lattice Dynamics: Combining dielectric crystals with mesoporous solids allows a versatile\ndesign of functional nanomaterials, where the porous host provides a mechanical\nrigid scaffold structure and the molecular filling adds the functionalization.\nHere, we report a study of the complex lattice dynamics of a\nSiO$_2$:KH$_2$PO$_4$ nanocomposite consisting of a monolithic, mesoporous\nsilica glass host with KH$_2$PO$_4$ nanocrystals embedded in its tubular\nchannels $\\sim$12 nm across. A micro-Raman investigation performed in the\nspectral range of 70-1600 cm$^{-1}$ reveals the complex lattice dynamics of the\nconfined crystals. Their Raman spectrum resembles the one taken from bulk\nKH$_2$PO$_4$ crystals and thus, along with X-ray diffraction experiments,\ncorroborates the successful solution-based synthesis of KH$_2$PO$_4$\nnanocrystals with a structure analogous to the bulk material. We succeeded in\nobserving not only the high-frequency internal modes ($\\sim$900-1200\ncm$^{-1}$), typical of internal vibrations of the PO$_4$ tetrahedra, but, more\nimportantly, also the lowest frequency modes typical of bulk KH$_2$PO$_4$\ncrystals. The experimental Raman spectrum was interpreted with a group theory\nanalysis and first-principle lattice dynamics calculations. The analysis of\ncalculated eigen-vectors indicates the involvement of hydrogen atoms in most\nphonon modes corroborating the substantial significance of the hydrogen\nsubsystem in the lattice dynamics of paraelectric bulk and of KH$_2$PO$_4$\ncrystals in extreme spatial confinement. A marginal redistribution of relative\nRaman intensities of the confined compared to unconfined crystals presumably\noriginates in slightly changed crystal fields and interatomic interactions, in\nparticular for the parts of the nanocrystals in close proximity to the silica\npore surfaces."
    },
    {
        "anchor": "Scalable and efficient separation of hydrogen isotopes using\n  graphene-based electrochemical pumping: Thousands of tons of isotopic mixtures are processed annually for heavy-water\nproduction and tritium decontamination. The existing technologies remain\nextremely energy intensive and require large capital investments. New\napproaches are needed to reduce the industry's footprint. Recently, micron-size\ncrystals of graphene were shown to act as efficient sieves for hydrogen\nisotopes pumped through graphene electrochemically. Here we report a\nfully-scalable approach, using graphene obtained by chemical vapor deposition,\nwhich allows a proton-deuteron separation factor of ca. 8, despite cracks and\nimperfections. The energy consumption is projected to be orders of magnitude\nsmaller with respect to existing technologies. A membrane based on 30 m2 of\ngraphene, a readily accessible amount, could provide a heavy-water output\ncomparable to that of modern plants. Even higher efficiency is expected for\ntritium separation. With no fundamental obstacles for scaling up, the\ntechnology's simplicity, efficiency and green credentials call for\nconsideration by the nuclear and related industries.",
        "positive": "On the characterisation of a hitherto unreported icosahedral\n  quasicrystal phase in additively manufactured aluminium alloy AA7075: Aluminium alloy AA7075 (Al-Zn-Mg-Cu) specimens were prepared using selective\nlaser melting, also known as powder bed fusion additive manufacturing. In the\nas-manufactured state, which represents a locally rapidly solidified condition,\nthe prevalence of a previously unreported icosahedral quasicrystal with 5-fold\nsymmetry was observed. The icosahedral quasicrystal, which has been termed\nnu-phase, was comprised of Zn, Cu and Mg."
    },
    {
        "anchor": "Magnetic Phases and Specific Heat of Ultra-Thin Holmium Films: We report model calculations of the magnetic phases of very thin Ho films in\nthe temperature interval between 20K and 132K, and show that slab size, surface\neffects and magnetic field due to spin ordering may impact significantly the\nmagnetic phase diagram. There is a relevant reduction of the external field\nstrength required to saturate the magnetization and for ultra-thin films the\nhelical state does not form. We explore the heat capacity and the\nsusceptibility as auxiliary tools to discuss the nature of the phase\ntransitions.",
        "positive": "Effects of Lagrangian Multipliers on SWCNT in Real Space: Electronic properties, band width, band gap and van Hove singularities, of\n(3,0), (4,0) and (9,0) zigzag nanotubes are comparatively investigated in the\nHarigaya's model and a toy model including the contributions of bonds of\ndifferent types to the SSH Hamiltonian differently. Optical transition\nfrequencies are calculated. In this way an experimental correlation between the\ntwo models is achieved."
    },
    {
        "anchor": "New challenges for the pressure evolution of the glass temperature: The ways of portrayal of the pressure evolution of the glass temperature (Tg)\nbeyond the dominated Simon-Glatzel-like pattern are discussed. This includes\nthe possible common description of Tg(P) dependences in systems described by\ndtg/dP>0 and dTg/dP<0. The latter is associated with the maximum of Tg(P) curve\nhidden in the negative pressures domain. The issue of volume and density\nchanges along the vitrification curve is also noted. Finally, the universal\npattern of vitrification associated with the crossover from the low density\n(isotropic stretching) to the high density (isotropic compression) systems is\nproposed. Hypothetically, it may obey any glass former, from molecular liquids\nto colloids.",
        "positive": "A first principles study of the stability and mobility of defects in\n  titanium carbide: We have performed density functional calculations of the formation energies\nof substitutional transition metal (TM) defects, C vacancies, and C\ninterstitial defects in TiC. In addition we have evaluated the migration energy\nbarriers for C atoms in the presence of TM impurities. We find that the\nsolubility of TM impurities taken from the 3d TM series is low and only Sc and\nV impurities can be dissolved into TiC at equilibrium. In addition, we find\nthat the migration energy barriers of C in TiC are greatly affected by the\npresence of TM impurities: The migration barriers are generally lower in the\npresence of impurities compared to pure TiC and show a clear dependence on the\natomic size of the TM impurities. We propose that the mobility of C in TiC will\nbe the highest in the presence of TM impurities from the middle of the 3d TM\nseries."
    },
    {
        "anchor": "Leveraging Uncertainty from Deep Learning for Trustworthy Materials\n  Discovery Workflows: In this paper, we leverage predictive uncertainty of deep neural networks to\nanswer challenging questions material scientists usually encounter in machine\nlearning based materials applications workflows. First, we show that by\nleveraging predictive uncertainty, a user can determine the required training\ndata set size necessary to achieve a certain classification accuracy. Next, we\npropose uncertainty guided decision referral to detect and refrain from making\ndecisions on confusing samples. Finally, we show that predictive uncertainty\ncan also be used to detect out-of-distribution test samples. We find that this\nscheme is accurate enough to detect a wide range of real-world shifts in data,\ne.g., changes in the image acquisition conditions or changes in the synthesis\nconditions. Using microstructure information from scanning electron microscope\n(SEM) images as an example use case, we show that leveraging uncertainty-aware\ndeep learning can significantly improve the performance and dependability of\nclassification models.",
        "positive": "Importance of Magnetism in Phase Stability, Equations of State, and\n  Elasticity: The effects of magnetism on high pressure properties of transition metals and\ntransition metal compounds can be quite important. In the case of Fe, magnetism\nis responsible for stability of the body-centered cubic (bcc) phase at ambient\nconditions, and the large thermal expansivity in face-centered cubic (fcc)\niron, and also has large effects on the equation of state and elasticity of\nhexagonal close-packed (hcp) iron. In transition metal oxides, local magnetic\nmoments are responsible for their insulating behavior. LDA+U results are\npresented for CoO and FeO, and predictions are made for high pressure\nmetallization. The inclusion of a local Coulomb repulsion, U, greatly inhibits\nthe high-spin low-spin transitions found with conventional exchange-correlation\nfunctionals (i.e. generalized gradient corrections, GGA). We discuss theory and\ncomputations for the effects of magnetism on high pressure cohesive properties."
    },
    {
        "anchor": "First principles theory of inelastic currents in a scanning tunneling\n  microscope: A first principles theory of inelastic tunneling between a model probe tip\nand an atom adsorbed on a surface is presented, extending the elastic tunneling\ntheory of Tersoff and Hamann. The inelastic current is proportional to the\nchange in the local density of states at the center of the tip due to the\naddition of the adsorbate. We use the theory to investigate the vibrational\nheating of an adsorbate below an STM tip. We calculate the desorption rate of H\nfrom Si(100)-H(2$\\times$1) as function of the sample bias and tunnel current,\nand find excellent agreement with recent experimental data.",
        "positive": "Dispersion Corrected DFT Study of Pentacene Thin Films on Flat and\n  Vicinal Au Surfaces: Here we a present a density functional theory study of pentacene ultra-thin\nfilms on flat [(111)] and vicinal [(455)] Au surfaces. We have performed\ncrystal and electronic structure calculations by using PBE and optB86b-vdW\nfunctionals and investigated the effects of long range Van der Waals\ninteractions for different coverages starting from a single isolated molecule\nup to 4 monolayers of coverage. For an isolated molecule both functionals yield\nthe hollow site as the most stable one with bridge-60 site being very close in\nenergy in case of optB86b-vdW. Binding strength of an isolated pentacene on the\nstep edge was found to be much larger than that on the terrace sites. Different\nexperimentally reported monolayer structures were compared and the (6 x 3) unit\ncell was found to be energetically more stable than the (2 x 2 $\\sqrt{7}$) and\n(2 x $\\sqrt{31}$) ones. For one monolayer films while dispersion corrected\ncalculations favored flat pentacene molecules on terraces, standard (PBE)\ncalculations either found tilted and flat configurations to be energetically\nsimilar (on (111) surface) or favored the tilted configuration (on (455)\nsurface). PDOS calculations performed with optB86b-vdW functional showed larger\ndispersion of molecular orbitals over the Au states for the (455) surface when\ncompared with the (111) surface, indicating an enhanced charge carrier\ntransport at the pentacene-gold interface in favor of the vicinal surface.\nStarting with the second monolayer, both functionals favored tilted\nconfigurations for both surfaces. Our results underline the importance of the\ndispersion corrections for the loosely bound systems like pentacene on gold and\nthe role played by step edges in determining the multilayer film structure and\ncharge transfer at the organic molecule-metal interface."
    },
    {
        "anchor": "Role of fluctuation, disorder and catalyst in graphite-diamond\n  transition: The pressure-induced structural transition from graphite to diamond is\ninvestigated by semi-empirical molecular dynamics simulation. The result shows\nthat the graphite-diamond transition is a cooperative process with large\nfluctuation. We studied catalyst-aided effect by introducing a simple model\ninto a conventional tight binding Hamiltonian of carbon bonding structure. The\nobtained result suggest that weak disorder in graphite not only accelerate the\ntransition to cubic diamond but also will be an origin of high-pressure\npolymorph of carbon, such as hexagonal diamond.",
        "positive": "Carrier-Specific Femtosecond XUV Transient Absorption of PbI2 Reveals\n  Ultrafast Nonradiative Recombination: Femtosecond carrier recombination in PbI2 is measured using tabletop\nhigh-harmonic extreme ultraviolet (XUV) transient absorption spectroscopy and\nultrafast electron diffraction. XUV absorption from 45 eV to 62 eV measures\ntransitions from the iodine 4d core level to the conduction band density of\nstates. Photoexcitation at 400 nm creates separate and distinct transient\nabsorption signals for holes and electrons, separated in energy by the 2.4 eV\nband gap of the semiconductor. The shape of the conduction band and therefore\nthe XUV absorption spectrum is temperature dependent, and nonradiative\nrecombination converts the initial electronic excitation to thermal excitation\nwithin picoseconds. Ultrafast electron diffraction (UED) is used to measure the\nlattice temperature and confirm the recombination mechanism. The XUV and UED\nresults support a 2nd-order recombination model with a rate constant of\n2.5x10-9 cm3/s."
    },
    {
        "anchor": "Picosecond transfer from short-term to long-term memory in analog\n  antiferromagnetic memory device: Experiments in materials with a compensated ordering of magnetic moments have\ndemonstrated a potential for approaching the thermodynamic limit of the fastest\nand least-dissipative operation of a digital memory bit. In addition, these\nmaterials are very promising for a construction of energy-efficient analog\ndevices with neuromorphic functionalities, which are inspired by\ncomputing-in-memory capabilities of the human brain. In this paper, we report\non experimental separation of switching-related and heat-related resistance\nsignal dynamics in memory devices microfabricated from CuMnAs antiferromagnetic\nmetal. We show that the memory variable multilevel resistance can be used as a\nlong-term memory (LTM), lasting up to minutes at room temperature. In addition,\nultrafast reflectivity change and heat dissipation from nanoscale-thickness\nCuMnAs films, taking place on picosecond to hundreds of nanoseconds time\nscales, can be used as a short-term memory (STM). Information about input\nstimuli, represented by femtosecond laser pulses, can be transferred from STM\nto LTM after rehearsals at picosecond to nanosecond times in these memory\ndevices, where information can be retrieved at times up to 10^15 longer than\nthe input pulse duration. Our results open a route towards ultra-fast low-power\nimplementations of spiking neuron and synapse functionalities using a resistive\nanalog antiferromagnetic memory.",
        "positive": "A data driven approach for cross-slip modelling in continuum dislocation\n  dynamics: Cross-slip is a thermally activated process by which screw dislocation\nchanges its glide plane to another slip plane sharing the same Burgers vector.\nThe rate at which this process happens is determined by a Boltzmann type\nexpression that is a function of the screw segment length and the stress acting\non the dislocation. In continuum dislocation dynamics (CDD), the information\nregarding the length of the screw dislocation segment and local stress state on\ndislocations are lost due to the coarse-grained representation of the density.\nIn this work, a data driven approach to characterize the lost information by\nanalyzing the discrete dislocation configurations is proposed to enable\ncross-slip modeling in the CDD framework in terms of the coarse-grained\ndislocation density and stress fields. The analysis showed that the screw\nsegment length follows an exponential distribution, and the stress\nfluctuations, defined as the difference between the stress on the dislocations\nand the mean field stress in CDD, follows a Lorentzian distribution. A novel\napproach for cross slip implementation in CDD employing the screw segment\nlength and stress fluctuation statistics was proposed and rigorously tested by\ncomparing the CDD cross-slip rates with discrete dislocation dynamics (DDD)\nrates. This approach has been applied in conjunction with three cross-slip\nmodels used in DDD simulations differing mainly in the functional form of cross\nslip activation energy. It was found that different cross-slip activation\nenergy formulations yielded different cross-slip rates, yet the effect on\nmechanical stress-strain response and dislocation density evolution was minimal\nfor the [001] type loading."
    },
    {
        "anchor": "An Improved CVM Entropy Functional for BCC Alloys: We explore the possibility of modifying the multiplicity of the basic cluster\nin the entropy functional used in the cluster variation method so that\ntruncation errors owing to finite size of the basic cluster may be corrected.\nThe numerical value of this multiplicity is found by requiring the modified CVM\nentropy functional (M-CVM) in the tetrahedron approximation for the\nbody-centered cubic structure to yield the exact critical temperatures for\nordering and phase separation. We demonstrate that very accurate values of the\norder parameter, correlation functions and the Gibbs function can be obtained\nfor ordered and disordered phases at arbitrary composition and temperature with\nM-CVM approach by comparing the results with those for Monte Carlo simulations.",
        "positive": "Gapped Ferromagnetic Graphene Nanoribbons: We theoretically design a graphene-based all-organic ferromagnetic\nsemiconductor by terminating zigzag graphene nanoribbons (ZGNRs) with organic\nmagnets. A large spin-split gap with 100% spin polarized density of states near\nthe Fermi energy is obtained, which is of potential application in spin\ntransistors. The interplays among electron, spin and lattice degrees of freedom\nare studied using the first-principles calculations combined with fundamental\nmodel analysis. All of the calculations consistently demonstrate that although\nno d electrons existing, the antiferromagnetic \\pi-\\pi exchange together with\nthe strong spin-lattice interactions between organic magnets and ZGNRs make the\nground state ferromagnetic. The fundamental physics makes it possible to\noptimally select the organic magnets towards practical applications."
    },
    {
        "anchor": "Extremely large magnetoresistance from electron-hole compensation in the\n  nodal loop semimetal ZrP$_2$: Several early transition metal dipnictides have been found to host\ntopological semimetal states and exhibit large magnetoresistance. In this\nstudy, we use angle-resolved photoemission spectroscopy (ARPES) and\nmagneto-transport to study the electronic properties of a new transition metal\ndipnictide ZrP$_2$. We find that ZrP$_2$ exhibits an extremely large and\nunsaturated magnetoresistance of up to 40,000 % at 2 K, which originates from\nan almost perfect electron-hole compensation. Our band structure calculations\nfurther show that ZrP$_2$ hosts a topological nodal loop in proximity to the\nFermi level. Based on the ARPES measurements, we confirm the results of our\ncalculations and determine the surface band structure. Our study establishes\nZrP$_2$ as a new platform to investigate near-perfect electron-hole\ncompensation and its interplay with topological band structures.",
        "positive": "Quartic Anharmonicity of Rattlers and Its Effect on Lattice Thermal\n  Conductivity of Clathrates from First Principles: We investigate the role of the quartic anharmonicity in lattice dynamics and\nthermal transport of type-I clathrate Ba$_{8}$Ga$_{16}$Ge$_{30}$ based on\n\\textit{ab initio} self-consistent phonon calculations. We show that the strong\nquartic anharmonicity of rattling guest atoms causes the hardening of\nvibrational frequencies of low-lying optical modes and thereby affects\ncalculated lattice thermal conductivities $\\kappa_{L}$ significantly, resulting\nin an improved agreement with experimental results including the deviation from\n$\\kappa_{L}\\propto T^{-1}$ at high temperature. Moreover, our static\nsimulations with various different cell volumes show a transition from\ncrystal-like to \\textit{glasslike} $\\kappa_{L}$ around 20 K. Our analyses\nsuggest that the resonance dip of $\\kappa_{L}$ observed in clathrates with\nlarge guest-free-spaces is attributed mainly to the strong Umklapp scattering\nof acoustic modes along with the presence of higher-frequency dispersive\noptical modes."
    },
    {
        "anchor": "Weak ferrimagnetism and multiple magnetization reversal in\n  \u03b1-Cr3(PO4)2: The chromium(II) orthophosphate {\\alpha}-Cr3(PO4)2 is a weak ferrimagnet with\nthe Curie temperature TC = 29 K confirmed by a \\lambda-type peak in specific\nheat. Dominant antiferromagnetic interactions in this system are characterized\nby the Weiss temperature {\\Theta} = - 96 K, indicating an intermediate\nfrustration ratio |{\\Theta}|/TC ~ 3. In its magnetically ordered states\n{\\alpha}-Cr3(PO4)2 exhibits a remarkable sequence of temperature-induced\nmagnetization reversals sensitive to the protocol of measurements, i.e. either\nfield-cooled or zero-field-cooled regimes. The reduction of the effective\nmagnetic moment 4.5 {\\mu}B/Cr2+, as compared to the spin-only moment 4.9\n{\\mu}B/Cr2+, cannot be ascribed to the occurence of the low-spin state in any\ncrystallographic site of the Jahn-Teller active 3d4 Cr2+ ions. X-ray absorption\nspectra at the K-edge indicate divalent chromium and unravel the high-spin\nstate of these ions at the L2,3-edges. Weak ferrimagnetism and multiple\nmagnetization reversal phenomena seen in this compound could be ascribed to\nincomplete cancellation and distortion of partial spontaneous magnetization\nfunctions of Cr2+ in its six crystallographically inequivalent positions.",
        "positive": "Oxidation effects on graded porous silicon anti-reflection coatings: Efficient anti-reflection coatings (ARC) improve the light collection and\nthereby increase the current output of solar cells. By simple electrochemical\netching of the Si wafer, porous silicon (PS) layers with excellent broadband\nanti-reflection properties can be fabricated. In this work, ageing of graded PS\nhas been studied using Spectroscopic Ellipsometry, Transmission Electron\nMicroscopy and X-ray Photoelectron Spectroscopy. During oxidation of PS\nelements such as pure Si (Si$^0$), Si$_2$O (Si$^+$), SiO (Si$^{2+}$),\nSi$_2$O$_3$ (Si$^{3+}$), and SiO$_2$ (Si$^{4+}$) are present. In addition both\nhydrogen and carbon is introduced to the PS in the form of Si$_3$SiH and CO.\nThe oxide grows almost linearly with time when exposed to oxygen, from an\naverage thickness of 0 - 3.8 nm for the surface PS. The oxidation is then\ncorrelated to the optical stability of multi-layered PS ARCs. It is found that\neven after extensive oxidation, the changes in the optical properties of the PS\nstructures are small."
    },
    {
        "anchor": "Prediction of activation energy barrier of island diffusion processes\n  using data-driven approaches: We present models for prediction of activation energy barrier of diffusion\nprocess of adatom (1-4) islands obtained by using data-driven techniques. A set\nof easily accessible features, geometric and energetic, that are extracted by\nanalyzing the variation of the energy barriers of a large number of processes\non homo-epitaxial metallic systems of Cu, Ni, Pd, and Ag are used along with\nthe activation energy barriers to train and test linear and non-linear\nstatistical models. A multivariate linear regression model trained with energy\nbarriers for Cu, Pd, and Ag systems explains 92% of the variation of energy\nbarriers of the Ni system, whereas the non-linear model using artificial neural\nnetwork slightly enhances the success to 93%. Next mode of calculation that\nuses barriers of all four systems in training, predicts barriers of randomly\npicked processes of those systems with significantly high correlation\ncoefficient: 94.4% in linear regression model and 97.7% in artificial neural\nnetwork model. Calculated kinetics parameters such as the type of frequently\nexecuted processes and effective energy barrier for Ni dimer and trimer\ndiffusion on the Ni(111) surface obtained from KMC simulation using the\npredicted (data-enabled) energy barriers are in close agreement with those\nobtained by using energy barriers calculated from interatomic interaction\npotential.",
        "positive": "Time-resolved photoemission apparatus achieving sub-20-meV energy\n  resolution and high stability: The paper describes a time- and angle-resolved photoemission apparatus\nconsisting of a hemispherical analyzer and a pulsed laser source. We\ndemonstrate 1.48-eV pump and 5.90-eV probe measurements at the >10.5-meV and\n>240-fs resolutions by use of fairly monochromatic 170-fs pulses delivered from\na regeneratively amplified Ti:sapphire laser system operating typically at 250\nkHz. The apparatus is capable to resolve the optically filled superconducting\npeak in the unoccupied states of a cuprate superconductor, Bi2Sr2CaCu2O8+d. A\ndataset recorded on Bi(111) surface is also presented. Technical descriptions\ninclude the followings: A simple procedure to fine-tune the spatio-temporal\noverlap of the pump-and-probe beams and their diameters; achieving a long-term\nstability of the system that enables a normalization-free dataset acquisition;\nchanging the repetition rate by utilizing acoustic optical modulator and\nfrequency-division circuit."
    },
    {
        "anchor": "Effects of alloying and strain on the magnetic properties of\n  Fe$_{16}$N$_2$: The electronic structure and magnetic properties of pure and doped\n{Fe$_{16}$N$_2$} systems have been studied in the local-density (LDA) and\nquasiparticle self-consistent {\\emph{GW}} approximations. The {\\emph{GW}}\nmagnetic moment of pure {Fe$_{16}$N$_2$} is somewhat larger compared to LDA but\nnot anomalously large. The effects of doping on magnetic moment and exchange\ncoupling were analyzed using the coherent potential approximation. The\ntheoretical Curie temperature in pure {Fe$_{16}$N$_2$} is significantly higher\nthan the measured value, which is attributed to the quality of available\nsamples and the interpretation of experimental results. We found that different\nFe sites contribute very differently to the magnetocrystalline anisotropy\nenergy (MAE), which offers a way to increase MAE by small additions of Co or\nTi. MAE also increases under tetragonal strain.",
        "positive": "Mechanical strength of atomic chains, surface skins, and nanograins: This report deals with the correlation between the mechanical strength and\nthermal stability of systems extending from monatomic chains to surface skins\nand solids over the whole range of sizes with emphasis on the significance of\natomic coordination imperfection. Derived solutions show that a competition\nbetween the bond order loss and the associated bond strength gain of the lower\ncoordinated atoms dictate the thermo-mechanics of the low dimensional systems.\nBond order loss lowers the atomic cohesive energy that determines the\ntemperature of melting (Tm), or the activation energy for atomic dislocation,\nwhereas bond strength gain enhances the energy density, or mechanical strength,\nin the surface skin. Therefore, the surface is harder at T << Tm whereas the\nsurface becomes softer when the T approaches the surface Tm that is lower than\nthe bulk due to bond order loss. Hence, the strained nanostructures are usually\nstiffer at low T whereas the harder skins melt easier. Quantitative information\nhas been obtained about the bonding identities in metallic monatomic chains and\ncarbon nanotubes. Solutions also enable us to reproduce the inverse Hall-Petch\nrelationship with clarification of factors dominating the transition from\nhardening to softening in the nanometer regime."
    },
    {
        "anchor": "Ultrafast photoconductivity and terahertz vibrational dynamics in\n  double-helix SnIP nanowires: Tin iodide phosphide (SnIP), an inorganic double-helix material, is a\nquasi-1D van der Waals semiconductor that shows promise in photocatalysis and\nflexible electronics. However, our understanding of the fundamental\nphotophysics and charge transport dynamics of this new material is limited.\nHere, we use time-resolved terahertz (THz) spectroscopy to probe the transient\nphotoconductivity of SnIP nanowire films and, with insight into the highly\nanisotropic electronic structure from quantum chemical calculations, measure an\nelectron mobility as high as 280 $cm^2V^{-1}s^{-1}$. Additionally, the THz\nvibrational spectrum reveals a photoexcitation-induced charge redistribution\nthat reduces the amplitude of a twisting mode of the outer SnI helix on\npicosecond timescales. Finally, we show that the carrier lifetime and mobility\nare limited by a trap density greater than $10^{18}\\,cm^{-3}$. Our results\nprovide insight into the optical excitation and relaxation pathways of SnIP and\ndemonstrate a remarkably high carrier mobility for such a soft and flexible\nmaterial.",
        "positive": "Current-induced nucleation and dynamics of skyrmions in a Co-based\n  Heusler alloy: We demonstrate room-temperature stabilization of dipolar magnetic skyrmions\nwith diameters in the range of $100$ nm in a single ultrathin layer of the\nHeusler alloy Co$_2$FeAl (CFA) under moderate magnetic fields. Current-induced\nskyrmion dynamics in microwires is studied with a scanning Nitrogen-Vacancy\nmagnetometer operating in the photoluminescence quenching mode. We first\ndemonstrate skyrmion nucleation by spin-orbit torque and show that its\nefficiency can be significantly improved using tilted magnetic fields, an\neffect which is not specific to Heusler alloys and could be advantageous for\nfuture skyrmion-based devices. We then show that current-induced skyrmion\nmotion remains limited by strong pinning effects, even though CFA is a magnetic\nmaterial with a low magnetic damping parameter."
    },
    {
        "anchor": "Can we prevent the \"dead layer\" formation at manganite interfaces?: The present work theoretically studies the possibility to hinder the\nformation of a \"dead\" layer at the interfaces in manganite superlattices. We\nshowed that this goal can be reached by using alkaline-earth simple oxides as\nalternating layers in very thin superlattices. Indeed, such alternating layer\npromotes the contraction of manganite layers at the interfaces and\n$d_{x^2-y^2}$ preferred $e_g$ orbital occupancy, while Boltzman's transport\ncalculations show an increase in conductivity. This result hold for different\nmanganites, different alkaline-earth simple oxides as well as different\nthicknesses of the two layers.",
        "positive": "Fast computation of magnetostatic fields by Non-uniform Fast Fourier\n  Transforms: The bottleneck of micromagnetic simulations is the computation of the\nlong-ranged magnetostatic fields. This can be tackled on regular N-node grids\nwith Fast Fourier Transforms in time N logN, whereas the geometrically more\nversatile finite element methods (FEM) are bounded to N^4/3 in the best case.\nWe report the implementation of a Non-uniform Fast Fourier Transform algorithm\nwhich brings a N logN convergence to FEM, with no loss of accuracy in the\nresults."
    },
    {
        "anchor": "Effects of intrinsic defects and alloying with Fe on the\n  half-metallicity of Co$_2$MnSi: The electronic structure and half-metallic gap of Co$_{2}$MnSi in the\npresence of crystallographic defects, partial Fe substitution for Mn, and\nthermal spin fluctuations are studied using the coherent potential\napproximation and the disordered local moment method. In the presence of 5\\% Co\nor Mn vacancies the Fermi level shifts down to the minority-spin valence-band\nmaximum. In contrast to NiMnSb, both types of Mn antisite defects in\nCo$_{2}$MnSi are strongly exchange-coupled to the host magnetization, and\nthermal spin fluctuations do not strongly affect the half-metallic gap. Partial\nsubstitution of Mn by Fe results in considerable changes in the Bloch spectral\nfunction near the Fermi level, which strongly deviate from the rigid-band\npicture. In particular, a light band with the Fe character crosses the Fermi\nlevel at about 50\\% concentration. At room temperature, Fe substitution of up\nto 30\\% slightly increases the spin polarization at the Fermi level.",
        "positive": "The high temperature Jahn-Teller transition in LaMn7O12: A first order structural Jahn-Teller transition at T_{JT} = 650 K has been\nrecently reported for the quadruple perovskite LaMn7O12 . We have carried out\nmagnetization and transport measurements below and above T_{JT} in order to\ninvestigate the effect of the transition. Electrical conduction turns out to be\npolaronic, changing from non-adiabatic to adiabatic through the transition.\nMagnetic behavior can be described by non-interacting Mn3+ ions below T_{JT},\nwhile above T_{JT} it is of questionable interpretation. The effect of thermal\ncycling on as grown samples of different purity degree also allowed us to\nclarify the intrinsic magnetic response of LaMn7O12 at lower temperatures."
    },
    {
        "anchor": "Brownian electric bubble quasiparticles: Recent works on electric bubbles (including the experimental demonstration of\nelectric skyrmions) constitute a breakthrough akin to the discovery of magnetic\nskyrmions some 15 years ago. So far research has focused on obtaining and\nvisualizing these objects, which often appear to be immobile (pinned) in\nexperiments. Thus, critical aspects of magnetic skyrmions - e.g., their\nquasiparticle nature, Brownian motion - remain unexplored (unproven) for\nelectric bubbles. Here we use predictive atomistic simulations to investigate\nthe basic dynamical properties of these objects in pinning-free model systems.\nWe show that it is possible to find regimes where the electric bubbles can\npresent long lifetimes ($\\sim$ ns) despite being relatively small ($\\varnothing\n<$ 2 nm). Additionally, we find that they can display stochastic dynamics with\nlarge and highly tunable diffusion constants. We thus establish the\nquasiparticle nature of electric bubbles and put them forward for the physical\neffects and applications (e.g., in token-based Probabilistic Computing)\nconsidered for magnetic skyrmions.",
        "positive": "Domain Size Dependence of Piezoelectric Properties of Ferroelectrics: The domain size dependence of piezoelectric properties of ferroelectrics is\ninvestigated using a continuum Ginzburg-Landau model that incorporates the\nlong-range elastic and electrostatic interactions. Microstructures with desired\ndomain sizes are created by quenching from the paraelectric phase by biasing\nthe initial conditions. Three different two-dimensional microstructures with\ndifferent sizes of the $90^{o}$ domains are simulated. An electric field is\napplied along the polar as well as non-polar directions and the piezoelectric\nresponse is simulated as a function of domain size for both cases. The\nsimulations show that the piezoelectric coefficients are enhanced by reducing\nthe domain size, consistent with recent experimental results of Wada and\nTsurumi (Brit. Ceram. Trans. {\\bf 103}, 93, 2004) on domain engineered\n$BaTiO_{3} $"
    },
    {
        "anchor": "High-Resolution Faraday Rotation and Electron-Phonon Coupling in Surface\n  States of the Bulk-Insulating Topological Insulator Cu$_{0.02}$Bi$_2$Se$_3$: We have utilized time-domain magneto-terahertz spectroscopy to investigate\nthe low frequency optical response of topological insulator\nCu$_{0.02}$Bi$_2$Se$_3$ and Bi$_2$Se$_3$ films. With both field and frequency\ndependence, such experiments give sufficient information to measure the\nmobility and carrier density of multiple conduction channels simultaneously. We\nobserve sharp cyclotron resonances (CRs) in both materials. The small amount of\nCu incorporated into the Cu$_{0.02}$Bi$_2$Se$_3$ induces a true bulk insulator\nwith only a \\textit{single} type of conduction with total sheet carrier density\n$\\sim4.9\\times10^{12}/$cm$^{2}$ and mobility as high as 4000\ncm$^{2}/$V$\\cdot$s. This is consistent with conduction from two virtually\nidentical topological surface states (TSSs) on top and bottom of the film with\na chemical potential $\\sim$145 meV above the Dirac point and in the bulk gap.\nThe CR broadens at high fields, an effect that we attribute to an\nelectron-phonon interaction. This assignment is supported by an extended Drude\nmodel analysis of the zero field Drude conductance. In contrast, in normal\nBi$_2$Se$_3$ films two conduction channels were observed and we developed a\nself-consistent analysis method to distinguish the dominant TSSs and coexisting\ntrivial bulk/2DEG states. Our high-resolution Faraday rotation spectroscopy on\nCu$_{0.02}$Bi$_2$Se$_3$ paves the way for the observation of quantized Faraday\nrotation under experimentally achievable conditions to push chemical potential\nin the lowest Landau Level.",
        "positive": "Optical Characterization of PtSi/Si by Spectroscopic Ellipsometry: We report optical characterization of PtSi films for thermoelectric device\napplications by nondestructive spectroscopic ellipsometry (SE). Pt monolayer\nand Pt-Si multilayer which consists of 3 pairs of Pt and Si layers were\ndeposited on p-doped-silicon substrates by sputtering method and then rapid\nannealing process was done to form PtSi films through intermixing of Pt and Si\natoms at the interface. Pseudodielectric function data <{\\epsilon}> =\n<{\\epsilon}1> + i<{\\epsilon}2> of the PtSi/Si samples were obtained from 1.12\nto 6.52 eV by using spectroscopic ellipsometry. Employing Tauc-Lorentz and\nDrude models, the dielectric function ({\\epsilon}) of PtSi films were\ndetermined. We found that the composition ratio of Pt:Si is nearly 1:1 for PtSi\nmonolayer and we observed transitions between occupied and unoccupied states in\nPt 5d states. We also observed formation of PtSi layers in Pt-Si multilayer\nsample. The SE results were confirmed by the transmission electron microscopy\nand energy dispersive X-ray spectroscopy."
    },
    {
        "anchor": "Spin Modulation in Semiconductor Lasers: We provide an analytic study of the dynamics of semiconductor lasers with\ninjection (pump) of spin-polarized electrons, previously considered in the\nsteady-state regime. Using complementary approaches of quasi-static and small\nsignal analyses, we elucidate how the spin modulation in semiconductor lasers\ncan improve performance, as compared to the conventional (spin-unpolarized)\ncounterparts. We reveal that the spin-polarized injection can lead to an\nenhanced bandwidth and desirable switching properties of spin-lasers.",
        "positive": "Spin-torque-induced magnetization dynamics in ferrimagnets based on\n  Landau-Lifshitz-Bloch Equation: A theoretical model based on the Landau-Lifshitz-Bloch equation is developed\nto study the spin-torque effect in ferrimagnets. Experimental findings, such as\nthe temperature dependence, the peak in spin torque, and the angular-momentum\ncompensation, can be well captured. In contrast to the ferromagnet system, the\nswitching trajectory in ferrimagnets is found to be precession free. The two\nsublattices are not always collinear, which produces large exchange field\naffecting the magnetization dynamics. The study of material composition shows\nthe existence of an oscillation region at intermediate current density, induced\nby the nondeterministic switching. Compared to the Landau-Lifshitz-Gilbert\nmodel, our developed model based on the Landau-Lifshitz-Bloch equation enables\nthe systematic study of spin-torque effect and the evaluation of\nferrimagnet-based devices."
    },
    {
        "anchor": "Coupling lattice instabilities across the interface in ultrathin oxide\n  heterostructures: Oxide heterointerfaces constitute a rich platform for realizing novel\nfunctionalities in condensed matter. A key aspect is the strong link between\nstructural and electronic properties, which can be modified by interfacing\nmaterials with distinct lattice symmetries. Here we determine the effect of the\ncubic-tetragonal distortion of $\\text{SrTiO}_3$ on the electronic properties of\nthin films of $\\text{SrIrO}_3$, a topological crystalline metal hosting a\ndelicate interplay between spin-orbit coupling and electronic correlations. We\ndemonstrate that below the transition temperature at 105 K, $\\text{SrIrO}_3$\northorhombic domains couple directly to tetragonal domains in $\\text{SrTiO}_3$.\nThis forces the in-phase rotational axis to lie in-plane and creates a binary\ndomain structure in the $\\text{SrIrO}_3$ film. The close proximity to the\nmetal-insulator transition in ultrathin $\\text{SrIrO}_3$ causes the individual\ndomains to have strongly anisotropic transport properties, driven by a\nreduction of bandwidth along the in-phase axis. The strong structure-property\nrelationships in perovskites make these compounds particularly suitable for\nstatic and dynamic coupling at interfaces, providing a promising route towards\nrealizing novel functionalities in oxide heterostructures.",
        "positive": "Driving skyrmions in flow regime in synthetic ferrimagnets: Despite significant advances in the last decade regarding the room\ntemperature stabilization of skyrmions or their current induced dynamics, the\nimpact of local material inhomogeneities still remains an important issue that\nimpedes to reach the regime of steady state motion of these spin textures.\nHere, we study the spin-torque driven motion of skyrmions in synthetic\nferrimagnetic multilayers with the aim of achieving high mobility and reduced\nskyrmion Hall effect. We consider Pt|Co|Tb multilayers of various thicknesses\nwith antiferromagnetic coupling between the Co and Tb magnetization. The\nincrease of Tb thickness in the multilayers allows to reduce the total magnetic\nmoment and increases the spin-orbit torques allowing to reach velocities up to\n400 m.s-1 for skyrmions with diameters of about 160 nm. We demonstrate that due\nto reduced skyrmion Hall effect, combined with the edge repulsion of the\nmagnetic track making the skyrmions moving along the track without any\ntransverse deflection. Further, by comparing the field-induced domain wall\nmotion and current-induced skyrmion motion, we demonstrate that the skyrmions\nat the largest current densities present all the characteristics of a dynamical\nflow regime."
    },
    {
        "anchor": "Can we rely on hybrid-DFT energies of solid-state problems with\n  local-DFT geometries?: Hybrid functionals often improve considerably the accuracy of\ndensity-functional calculations, in particular of quantities resulting from the\nband structure. In plane-wave (PW) calculations this benefit comes at the cost\nof an increase in computation time by several orders of magnitude. For this\nreason, large-scale problems addressed within the PW formalism have to rely on\npre-relaxed atomistic geometries, obtained with cheaper local or semi-local\nexchange-correlation functionals. We investigate how suitable these geometries\nare when plugged into single-point hybrid-DFT calculations. Based on several\ncase studies, we find two important sources of error originating from (i) bond\nstrain and (ii) over-mixing between defect and crystalline states. The first\narises from the mismatch between the pre-relaxed geometry and that obtained\nafter a subsequent hybrid-DFT-level relaxation. The second occurs when defect\nstates edging an underestimated band gap artificially mix with crystalline\nstates, affecting the local bonding character of the defect, and therefore\nleading the spurious hybrid-DFT energies. Due to cancelation effects, the\nlingering strain contributes little ($\\lesssim10$ meV) to the error bar of\nquantities based on energy differences of pre-relaxed structures. The error\nfrom state over-mixing does not benefit from cancelation effects and has to be\nmonitored with caution.",
        "positive": "Anisotropic Proton and Oxygen Ion Conductivity in Epitaxial Ba2In2O5\n  Thin Films: Solid oxide oxygen ion and proton conductors are a highly important class of\nmaterials for renewable energy conversion devices like solid oxide fuel cells.\nBa2In2O5 (BIO) exhibits both oxygen ion and proton conduction, in dry and humid\nenvironment, respectively. In dry environment, the brownmillerite crystal\nstructure of BIO exhibits an ordered oxygen ion sublattice, which has been\nspeculated to result in anisotropic oxygen ion conduction. The hydrated\nstructure of BIO, however, resembles a perovskite and the protons in it were\npredicted to be ordered in layers. To complement the significant theoretical\nand experimental efforts recently reported on the potentially anisotropic\nconductive properties in BIO, we measure here the proton and oxygen ion\nconductivity along different crystallographic directions. Using epitaxial thin\nfilms with different crystallographic orientations the charge transport for\nboth charge carriers is shown to be anisotropic. The anisotropy of the oxygen\nion conduction can indeed be explained through the layered structure of the\noxygen sublattice in brownmillerite BIO. The anisotropic proton conduction\nhowever, further supports the suggested ordering of the protonic defects in the\nmaterial. The differences in proton conduction along different crystallographic\ndirections attributed to proton ordering in BIO are of a similar extent as\nthose observed along different crystallographic directions in materials where\nproton ordering is not present but where protons find preferential conduction\npathways through chain-like or layered structures."
    },
    {
        "anchor": "Zinc Oxide Modified with Benzylphosphonic Acids as Transparent\n  Electrodes in Regular and Inverted Organic Solar Cell Structures: An approach is presented to modify the WF of solution-processed sol-gel\nderived ZnOover an exceptionally wide range of more than 2.3 eV. This approach\nrelies on the formation of dense and homogeneous self-assembled monolayers\nbased on phosphonic acids with different dipole moments. This allows us to\napply ZnO as charge selective bottom electrodes in either regular or inverted\nsolar cell structures, using P3HT:PCBM as the active layer. These devices\ncompete with or even exceed the performance of the reference cell on\nITO/PEDOT:PSS. Our finding challenges the current view that bottom electrodes\nin inverted solar cells need to be electron-blocking for good device\nperformance.",
        "positive": "Engineering ultra-strong Mg-Li-Al-based light-weight alloys from first\n  principles: Light-weight alloys are essential pillars of transportation technologies.\nThey also play a crucial role to achieve a more green and cost-effective\naerospace technologies. Magnesium-lithium-aluminum (Mg-Li-Al) alloys are\nauspicious candidates due to their promising mechanical strengths at low\ndensities. We herein present a systematic first-principles investigation of the\nMg-Li-Al-based alloys to provide insights for designing ultra-strong\nlight-weight alloys. Initial analysis indicates that the Mg-Li-Al mixtures are\nnot thermally stabilized into random-solid solutions. Following this hint, the\nbase-centered cubic (BCC)-based intermetallics of Mg, Li and Al are\ninvestigated for their thermal and elastic stabilities.Three simple figures of\nmerits are used to further assess their mechanical strengths. The\nmost-frequently observed intermetallics are used to predict the yield strength\nof the hetero-structures from the recent experimental works. The rule of mixing\nworks reasonable well to predict the mechanical properties of complex\nstructures starting from isolated intermetallics."
    },
    {
        "anchor": "Lattice coupled first order magnetoresistance transition in an A-type\n  antiferromagnet: Pr$_{0.46}$Sr$_{0.54}$MnO$_3$: We investigated magnetic, magnetotransport and magnetostriction properties of\nthe A-type antiferromagnet Pr$_{0.46}$Sr$_{0.54}$MnO$_3$ which undergoes a\nfirst order paramagnetic-antiferromagnetic transition below T$_N$ = 210 K while\ncooling and T$_N$ = 215 K while warming. The zero field ($\\mu_0$H = 0 T)\nresistivity shows a sudden jump at T$_N$ and a small bump around T$_{max}$ =\n220 K (\\TEXTsymbol{>} T$_N$). T$_N$ shifts down and T$_{max}$ shifts up with\nincreasing $\\mu_0$H. Magnetoresistance as high as -45-57 % at 7 T is found in\nthe temperature range 180 K-230 K. Isothermal measurements indicate that the\nfield induced antiferromagnetic to ferromagnetic transition below T$_N$ is\naccompanied by a rapid decrease of the resistivity but increase of volume\n($\\Delta $V/V = +0.25 % at 180 K and 13.7 T). This lattice coupled\nmagnetoresistance transition is suggested due to the field induced structural\ntransition from the low volume orthorhombic to the high volume tetragonal\nstructure.",
        "positive": "Universal Effective Medium Theory to Predict the Thermal Conductivity in\n  Nanostructured Materials: Nanostructured materials enable high thermal transport tunability, holding\npromises for thermal management and heat harvesting applications. Predicting\nthe effect that nanostructuring has on thermal conductivity requires models,\nsuch as the Boltzmann transport equation (BTE), that capture the non-diffusive\ntransport of phonons. Although the BTE has been well validated against several\nkey experiments, notably those on nanoporous materials, its applicability is\ncomputationally expensive. Several effective model theories have been put\nforward to estimate the effective thermal conductivity; however, most of them\nare either based on simple geometries, e.g., thin films, or simplified material\ndescriptions such as the gray-model approximation. To fill this gap, we propose\na model that takes into account the whole mean-free-path (MFP) distribution as\nwell as the complexity of the material's boundaries in infinitely thick films\nwith extruded porosity using uniparameter logistic regression. We validate our\napproach, which is called the \"Ballistic Correction Model\" (BCM), against full\nBTE simulations of a selection of three base materials (GaAs, InAs, and Si)\nwith nanoscale porosity, obtaining excellent agreement. While the key\nparameters of our method, associated with the geometry of the bulk material,\nare obtained from the BTE, they can be decoupled and used in arbitrary\ncombinations and scales. We tabulated these parameters for a few cases,\nenabling the exploration of systems that are beyond those considered in this\nwork. Providing a simple yet accurate estimation of thermal transport in\nnanostructures, our work sets out to accelerate the discovery of materials for\nthermal-related applications."
    },
    {
        "anchor": "Anharmonicity Measure for Materials: Theoretical frameworks used to qualitatively and quantitatively describe\nnuclear dynamics in solids are often based on the harmonic approximation.\nHowever, this approximation is known to become inaccurate or to break down\ncompletely in many modern functional materials. Interestingly, there is no\nreliable measure to quantify anharmonicity so far. Thus, a systematic\nclassification of materials in terms of anharmonicity and a benchmark of\nmethodologies that may be appropriate for different strengths of anharmonicity\nis currently impossible. In this work, we derive and discuss a statistical\nmeasure that reliably classifies compounds across temperature regimes and\nmaterial classes by their \"degree of anharmonicity\". This enables us to\ndistinguish \"harmonic\" materials, for which anharmonic effects constitute a\nsmall perturbation on top of the harmonic approximation, from strongly\n\"anharmonic\" materials, for which anharmonic effects become significant or even\ndominant and the treatment of anharmonicity in terms of perturbation theory is\nmore than questionable. We show that the analysis of this measure in real and\nreciprocal space is able to shed light on the underlying microscopic\nmechanisms, even at conditions close to, e.g., phase transitions or defect\nformation. Eventually, we demonstrate that the developed approach is\ncomputationally efficient and enables rapid high-throughput searches by\nscanning over a set of several hundred binary solids. The results show that\nstrong anharmonic effects beyond the perturbative limit are not only active in\ncomplex materials or close to phase transitions, but already at moderate\ntemperatures in simple binary compounds.",
        "positive": "$C_2C_N$ as a 2 eV Single-Photon Emitter Candidate in Hexagonal Boron\n  Nitride: The generation of single-photon emitters in hexagonal boron nitride around 2\neV emission is experimentally well-recognized; however the atomic nature of\nthese emitters is unknown. In this paper, we use first-principles calculations\nto demonstrate that $C_2C_N$ is a possible source of 2 eV single-photon\nemitter. We showcase the calculations of a complete set of static and dynamical\nproperties related to defects, including exciton-defect couplings and\nelectron-phonon interactions. In particular, we show it is critical to consider\nnonradiative processes when comparing with experimental lifetime for known 2 eV\nemitters. We find that $C_2C_N$ has several key physical properties matching\nthe ones of experimentally observed single-photon emitters. These include the\nzero-phonon line (2.13eV), Huang-Rhys factor (1.35), photoluminescence lifetime\n(2.19 ns), phonon-sideband energy (180meV), and photoluminescence spectrum. The\nidentification of defect candidates for 2 eV emission paves the way for\ncontrollable single-photon emission generation."
    },
    {
        "anchor": "Giant magnetodielectric metamaterial: Dielectric materials with tunable permittivity are highly desirable for\nwireless communication, radar technology. However, the tunability of dielectric\nproperties in the microwave frequency range and higher is an immense challenge\nfor conventional materials. Here, we demonstrate a giant magnetodielectric\neffect in the GHz region in a metamaterial based on ferrite unit cells. The\neffect is derived from the coupling of the ferromagnetic resonance and the Mie\nresonance in the ferrite unit cells. Both the simulated and experimental\nresults indicate that the effective permittivity of the metamaterial can be\ntuned by modifying the applied magnetic field, and a giant magnetodielectric\neffect, [{\\epsilon}'(H) - {\\epsilon}'(0)]/{\\epsilon}'(0) = 15000 % at 11.284\nGHz, is obtained. This mechanism offers a promising means of constructing\nmicrowave dielectrics with large tunable ranges and considerable potential for\ntailoring via a metamaterial route.",
        "positive": "Rigid unit modes in tetrahedral crystals: The 'rigid unit mode' (RUM) model requires unit blocks, in our case\ntetrahedra of SiO_4 groups, to be rigid within first order of the displacements\nof the O-ions. The wave-vectors of the lattice vibrations, which obey this\nrigidity, are determined analytically. Lattices with inversion symmetry yield\ngenerically surfaces of RUMs in reciprocal space, whereas lattices without this\nsymmetry yield generically lines of RUMs. Only in exceptional cases as in\nbeta-quartz a surface of RUMs appears, if inversion symmetry is lacking. The\noccurence of planes and bending surfaces, straight and bent lines is discussed.\nExplicit calculations are performed for five modifications of SiO_2 crystals."
    },
    {
        "anchor": "Electron energy loss and induced photon emission in photonic crystals: The interaction of a fast electron with a photonic crystal is investigated by\nsolving the Maxwell equations exactly for the external field provided by the\nelectron in the presence of the crystal. The energy loss is obtained from the\nretarding force exerted on the electron by the induced electric field. The\nfeatures of the energy loss spectra are shown to be related to the photonic\nband structure of the crystal. Two different regimes are discussed: for small\nlattice constants $a$ relative to the wavelength of the associated electron\nexcitations $\\lambda$, an effective medium theory can be used to describe the\nmaterial; however, for $a\\sim\\lambda$ the photonic band structure plays an\nimportant role. Special attention is paid to the frequency gap regions in the\nlatter case.",
        "positive": "Design of a spin-wave majority gate employing mode selection: The design of a microstructured, fully functional spin-wave majority gate is\npresented and studied using micromagnetic simulations. This all-magnon logic\ngate consists of three-input waveguides, a spin-wave combiner and an output\nwaveguide. In order to ensure the functionality of the device, the output\nwaveguide is designed to perform spin-wave mode selection. We demonstrate that\nthe gate evaluates the majority of the input signals coded into the spin-wave\nphase. Moreover, the all-magnon data processing device is used to perform logic\nAND-, OR-, NAND- and NOR- operations."
    },
    {
        "anchor": "EuCd$_2$As$_2$: a magnetic semiconductor: EuCd$_2$As$_2$ is now widely accepted as a topological semimetal in which a\nWeyl phase is induced by an external magnetic field. We challenge this view\nthrough firm experimental evidence using a combination of electronic transport,\noptical spectroscopy and excited-state photoemission spectroscopy. We show that\nthe EuCd$_2$As$_2$ is in fact a semiconductor with a gap of 0.77 eV. We show\nthat the externally applied magnetic field has a profound impact on the\nelectronic band structure of this system. This is manifested by a huge decrease\nof the observed band gap, as large as 125~meV at 2~T, and consequently, by a\ngiant redshift of the interband absorption edge. However, the semiconductor\nnature of the material remains preserved. EuCd$_2$As$_2$ is therefore a\nmagnetic semiconductor rather than a Dirac or Weyl semimetal, as suggested by\n{\\em ab initio} computations carried out within the local spin-density\napproximation.",
        "positive": "Internal dipolar field and soft magnons in periodic nanocomposite\n  magnets: We study spin wave excitations in a three-dimensional nanocomposite magnet of\nexchange coupled hard (SmCo$_5$) and soft (FeCo) phases. The dipolar\ninteraction splits the spin wave energies into the upper and lower branches of\nthe spin wave manifold. When the amount of the soft phase is increased the\nenergy of low-lying spin excitations is considerably softened due to two\nreasons: (i) the low- lying mode locked into the soft phase region with a spin\nwave gap at ${\\bf k}= 0$ which scales approximately proportional to the\nanisotropy constant of the soft phase and (ii) the internal dipolar field which\ncomes from magnetic charges forming at hard-soft boundaries with normals\nparallel to the magnetization displaces the spin wave manifold toward the lower\nenergies. With adding more soft phase the spin wave gap closes and the system\nmoves to another ground state characterized by the magnetization mismatch\nbetween spins of the hard and soft phases."
    },
    {
        "anchor": "Bias sputtering of granular $\\text{L1}_0$-FePt films with hexagonal\n  boron nitride grain boundaries: In this paper, we present an experimental study of $\\text{L1}_0$-FePt\ngranular films with crystalline/amorphous boron nitride (BN) grain boundary\nmaterials for heat assisted magnetic recording (HAMR). It is found that an\nadequate RF substrate bias yields the formation of hexagonal boron nitride\n(h-BN) nanosheets in grain boundaries, facilitating the columnar growth of FePt\ngrains during sputtering at high temperatures. The h-BN monolayers conform to\nthe side surfaces of columnar FePt grains, completely encircling individual\nFePt grains. The resulting core-shell FePt/h-BN nanostructures appear to be\nhighly promising for HAMR application. The high thermal stability of h-BN grain\nboundaries allows the deposition temperature to be as high as 800oC such that\nhigh order parameters of FePt $\\text{L1}_0$ phase have been obtained. For the\nfabricated FePt/h-BN thin film, excellent granular microstructure with FePt\ngrains of 6.5nm in diameter and 11.5nm in height has been achieved along with\ngood magnetic hysteresis properties.",
        "positive": "Computer Simulations of Thermal Switching in Small-grain Ferromagnets: We present Monte Carlo and Langevin micromagnetic calculations to investigate\nthermal switching of single-domain ferromagnetic particles. For the Monte Carlo\nstudy we place particular emphasis on the probability that the magnetization\ndoes not switch by time t. We find that this quantity has different behaviors\nin different regimes of applied field, temperature, and system size, and we\nexplain this in terms of different reversal mechanisms that dominate in the\ndifferent regimes. In the micromagnetic study of an array of Ni pillars, we\nshow that the reversal mode is an outside-in mode starting at the perimeter of\nthe array of pillars."
    },
    {
        "anchor": "Surface Second Harmonic Generation from Topological Dirac Semimetal\n  PdTe$_2$: Recent experiments and calculations in topological semimetals have observed\nanomalously strong second-order optical nonlinearity, but yet whether the\nenhancement also occurs at surfaces of topological semimetals in general\nremains an open question. In this work, we tackle this problem by measuring\npolarization-dependent and rotational-anisotropy optical second harmonic\ngeneration (SHG) from centrosymmetric type-II Dirac semimetal PdTe$_2$. We\nfound the SHG to follow C$_{3v}$ surface symmetry with a time-varying intensity\ndictated by the oxidation kinetics of the material after its surface cleavage,\nindicating the surface origin of SHG. Quantitative characterization of the\nsurface nonlinear susceptibility indicates a large out-of-plane response of\nPdTe$_2$ with $|\\chi_{ccc}^{(2)}|$ up to 25 $\\times$ 10$^{-18}$ m$^2$/V. Our\nresults support the topological surfaces/interfaces as a new route toward\napplications of nonlinear optical effects with released symmetry constraints,\nand demonstrate SHG as a viable means to in situ study of kinetics of\ntopological surfaces.",
        "positive": "Spectral narrowing of a phonon resonance in time-domain sum-frequency\n  spectroscopy: Sum-frequency generation (SFG) spectroscopy provides a versatile method for\nthe investigation of non-centrosymmetric media and interfaces. Here, using\ntunable picosecond infrared (IR) pulses from a free-electron laser, the\nnonlinear optical response of 4H-SiC, a common polytype of silicon carbide, has\nbeen probed in the frequency- and time-domain by infrared-visible vibrational\nSFG spectroscopy. In the SFG spectra we observe a sharp resonance near the\nlongitudinal optical phonon frequency, arising from linear optical effects due\nthe epsilon-near-zero regime of the IR permittivity. In the time domain, the\nbuild-up of the SFG intensity is linked to the free-induction decay of the\ninduced coherent IR polarization. When approaching the frequency of the phonon\nresonance, a slower polarization dephasing is observed as compared to\noff-resonant IR excitation. Thus, by introducing a temporal delay between the\nIR and the visible up-conversion pulse we are able to demonstrate spectral\nnarrowing of the phonon SFG resonance, as corroborated by model calculations."
    },
    {
        "anchor": "Jacutingaite-family: a class of topological materials: Jacutingate, a recently discovered Brazilian naturally occurring mineral, has\nshown to be the first experimental realization of the Kane-Mele topological\nmodel. In this letter we have unveiled a class of materials $M_2NX_3$ ($M$=Ni,\nPt, Pd; $N$=Zn, Cd, Hg; and $X$=S, Se, Te), sharing jacutingaite's key\nfeatures, i.e., high stability, and topological phase. By employing\nfirst-principles calculations we extensively characterize the energetic\nstability of this class while showing a common occurrence of the Kane-Mele\ntopological phase. Here we found Pt-based materials surpassing jacutingaite's\nimpressive topological gap and lower exfoliation barrier while retaining its\nstability.",
        "positive": "(CaO)(FeSe): A Layered Wide Gap Oxychalcogenide Semiconductor: A new iron-oxychalcogenide (CaO)(FeSe) was obtained which crystallizes in the\northorhombic space group Pnma (No. 62) with a = 5.9180(12) {\\AA}, b = 3.8802(8)\n{\\AA}, c = 13.193(3) {\\AA}. The unique structure of (CaO)(FeSe) is built up of\na quasi-two-dimensional network of corrugated infinite layers of corner-shared\nFeSe2O2 tetrahedra that extend in the ab-plane. The corrugated layers composed\nof corner-shared FeSe2O2 tetrahedra stack along the c-axis with Ca2+ cations\nsandwiched between the layers. Optical spectroscopy and resistivity\nmeasurements reveal semiconducting behavior with an indirect optical band gap\nof around 1.8 eV and an activation energy of 0.19(1) eV. Electronic band\nstructure calculations at the density function level predict a magnetic\nconfiguration as ground state and confirm the presence of an indirect wide gap\nin (CaO)(FeSe)."
    },
    {
        "anchor": "Effect of the surface polarization in polar perovskites studied from\n  first principles: The (001) surfaces of polar perovskites BaTiO$_3$ and PbTiO$_3$ have been\nstudied from first principles at T=0 K. For both cases of polarization, the\nmost stable TiO-terminated interfaces show intrinsic ferroelectricity. In the\ntopmost layer, where the O atoms are $>$0.1 \\AA above Ti, this leads to\nmetallic instead of the insulating behavior of the electronic states that may\nhave important implications for multiferroic tunneling junctions.",
        "positive": "Electronic, vibrational and thermodynamic properties of beta-HgS\n  (metacinnabar), HgSe and HgTe: We report ab initio calculations of the electronic band structure and the\nphonon dispersion relations of the zincblende-type mercury chalcogenides\n(beta-HgS, HgSe, and HgTe). The latter have been used to evaluate the\ntemperature dependence of the specific heat which has been compared with\nexperimental data. The electronic band structure of these materials has been\nconfirmed to have an inverted direct gap of the alpha-tin type, which makes\nHgSe and HgTe semimetallic. For beta-HgS, however, our calculations predict a\nnegative spin-orbit splitting which restores semiconducting properties to the\nmaterial in spite of the inverted gap. We have calculated the spin-orbit\ninduced linear terms in k which appear at the Gamma_8 valence bands. We have\nalso investigated the pressure dependence of the crystal structure and the\nphonons."
    },
    {
        "anchor": "Stress Transfer Mechanisms at the Submicron Level for Graphene/Polymer\n  Systems: The stress transfer mechanism from a polymer substrate to a nano-inclusion,\nsuch as a graphene flake, is of extreme interest for the production of\neffective nanocomposites. Previous work conducted mainly at the micron scale\nhas shown that the intrinsic mechanism of stress transfer is shear at the\ninterface. However, since the interfacial shear takes its maximum value at the\nvery edge of the nano-inclusion it is of extreme interest to assess the effect\nof edge integrity upon axial stress transfer at the submicron scale. Here, we\nconduct a detailed Raman line mapping near the edges of a monolayer graphene\nflake which is simply supported onto an epoxy based photoresist\n(SU8)/poly(methyl methacrylate) (PMMA) matrix at steps as small as 100 nm. We\nshow for the first time that, the distribution of axial strain (stress) along\nthe flake deviates somewhat from the classical shear-lag prediction for a\nregion of about 2 um from the edge. This behavior is mainly attributed to the\npresence of residual stresses, unintentional doping and/or edge effects\n(deviation from the equilibrium values of bond lengths and angles, as well as\ndifferent edge chiralities). By considering a simple balance of shear-to-normal\nstresses at the interface we are able to directly convert the strain (stress)\ngradient to values of interfacial shear stress for all the applied tensile\nlevels without assuming classical shear-lag behavior. For large flakes a\nmaximum value of interfacial shear stress (ISS) of 0.4 MPa is obtained prior to\nflake slipping.",
        "positive": "The Effect of Nanoparticle Shape on Polymer-Nanocomposite Rheology and\n  Tensile Strength: Nanoparticles can influence the properties of polymer materials by a variety\nof mechanisms. With fullerene, carbon nanotube, and clay or graphene sheet\nnanocomposites in mind, we investigate how particle shape influences the melt\nshear viscosity $\\eta$ and the tensile strength $\\tau$, which we determine via\nmolecular dynamics simulations. Our simulations of compact (icosahedral), tube\nor rod-like, and sheet-like model nanoparticles indicate an order of magnitude\nincrease in the viscosity $\\eta$ relative to the pure melt. This finding\nevidently can not be explained by continuum hydrodynamics and we provide\nevidence that the $\\eta$ increase in our model nanocomposites has its origin in\nchain bridging between the nanoparticles. We find that this increase is the\nlargest for the rod-like nanoparticles and least for the sheet-like\nnanoparticles. Curiously, the enhancements of $\\eta$ and $\\tau$ exhibit {\\it\nopposite trends} with increasing chain length $N$ and with particle shape\nanisotropy. Evidently, the concept of bridging chains alone cannot account for\nthe increase in $\\tau$ and we suggest that the deformability or flexibility of\nthe sheet nanoparticles contributes to nanocomposite strength and toughness by\nreducing the relative value of the Poisson ratio of the composite. Our\nsimulations point to a substantial contribution of nanoparticle shape to both\nmechanical and processing properties of polymer nanocomposites."
    },
    {
        "anchor": "Quantum Spin Hall Effect in Ta$_2$M$_3$Te$_5$ (M = Pd, Ni): Quantum spin Hall (QSH) effect with great promise for the potential\napplication in spintronics and quantum computing has attracted extensive\nresearch interest from both theoretical and experimental researchers. Here, we\npredict monolayer Ta$_2$Pd$_3$Te$_5$ can be a QSH insulator based on\nfirst-principles calculations. The interlayer binding energy in the layered van\nder Waals compound Ta$_2$Pd$_3$Te$_5$ is 19.6 meV/A$^2$; thus, its\nmonolayer/thin-film structures could be readily obtained by exfoliation. The\nband inversion near the Fermi level ($E_F$) is an intrinsic characteristic,\nwhich happens between Ta-$5d$ and Pd-$4d$ orbitals without spin-orbit coupling\n(SOC). The SOC effect opens a global gap and makes the system a QSH insulator.\nWith the $d$-$d$ band-inverted feature, the nontrivial topology in monolayer\nTa$_2$Pd$_3$Te$_5$ is characterized by the time-reversal topological invariant\n$\\mathbb Z_2=1$, which is computed by the one-dimensional (1D) Wilson loop\nmethod as implemented in our first-principles calculations. The helical edge\nmodes are also obtained using surface Green's function method. Our calculations\nshow that the QSH state in Ta$_2M_3$Te$_5$ ($M=$ Pd, Ni) can be tuned by\nexternal strain. These monolayers and thin films provide feasible platforms for\nrealizing QSH effect as well as related devices.",
        "positive": "Switching dynamics of morphology-structure in chemically deposited\n  carbon films -a new insight: Carbon is one of the most investigated materials and shows chaotic behavior\nin terms of evolving structure. Synthesizing carbon materials largely depend on\nthe deposition technique, process parameters, condition of substrate surface\nand ratios of the gaseous chemistry. A variety of techniques have been employed\nto depositing carbon films from various gaseous mixtures to different substrate\nmaterials. In this study, carbon thin and thick films are discussed for\ndifferent techniques known as hot filament chemical vapor deposition and\nmicrowave plasma chemical vapor deposition where their synthesis process has\nbeen explained in a new context. Here, we discuss attained dynamics of atoms or\ntiny grains amalgamating into a particular phase of grain or crystallite and\nelectron-dynamics responsible for binding atoms in the formation of all sorts\nof tiny grains, grains and crystallites controlling overall\nmorphology-structure of films thickness at few nanometers to several microns.\nCarbon atoms when in solid state, on amalgamation at flat surface result into\nbind under uniform electron-dynamics and when the amalgamation is at uneven\nsurface, they result into bind under non-uniform electron-dynamics. Substrates\nunder appropriate surface defects or abrasion result into an improved rate of\nnucleation of tiny grains, hence, their increased rate of growth. This study\nembarks on unexplored science of carbon films where in addition to localized\nprocess parameters nature of substrate also influence dynamics of formation of\ntiny clusters, grains and crystallites at their initial stage of formation. Our\nresults and discussions enlighten us to revisit the nucleation and growth\nmechanisms of different sorts of films deposit at any scale and at any\nsubstrate surface constituting different composition."
    },
    {
        "anchor": "Observation of Log-Periodic Oscillations in the Quantum Dynamics of\n  Electrons on the One-Dimensional Fibonacci Quasicrystal: We revisit the question of quantum dynamics of electrons on the off-diagonal\nFibonacci tight-binding model. We find that typical dynamical quantities, such\nas the probability of an electron to remain in its original position as a\nfunction of time, display log-periodic oscillations on top of the leading-order\npower-law decay. These periodic oscillations with the logarithm of time are\nsimilar to the oscillations that are known to exist with the logarithm of\ntemperature in the specific heat of Fibonacci electrons, yet they offer new\npossibilities for the experimental observation of this unique phenomenon.",
        "positive": "Electronic Properties of Various Graphene Quantum Dot Structures: an Ab\n  Initio Study: Density functional theory (DFT) and thermal DFT (thDFT) calculations were\nused to evaluate the energy band structure, bandgap, and the total energy of\nvarious graphene quantum dots (GQDs). The DFT calculations were performed using\nlocal density approximation for the exchange-correlation functional and\nnorm-conserving pseudopotentials. We consider the triangular and hexagonal GQDs\nwith zigzag and armchair edges and 1-3 nm dimensions with many hundred atoms.\nThe simulation results show that all of these GQDs are direct bandgap\nsemiconductors with a flat band structure, and they are suitable for\nelectronics and optoelectronics applications. Analysis of GQDs in which the A\nand B sublattice symmetries were broken showed degenerate zero-energy shells.\nUsing the thDFT calculations carried out at temperatures up to 1400 K, we\nevaluated the temperature dependence of the GQDs bandgaps and total energies\nvia entropy-term and electron kinetic energy. The obtained results indicate\nthat the ground-state DFT calculations are valid for determining the electronic\nproperties of GQDs up to room temperature. Moreover, we tune semi-empirical\nparameters of the tight-binding model by the DFT results in small GQDs to\nreduce the computational cost of electronic structure calculations for large\nGQDs, which contained up to thousands of atoms."
    },
    {
        "anchor": "Spin valve effect in two-dimensional VSe$_2$ system: Vanadium based dichalcogenides, VSe$_2$, are two-dimensional materials in\nwhich magnetic Vanadium atoms are arranged in a hexagonal lattice and are\ncoupled ferromagnetically within the plane. However, adjacent atomic planes are\ncoupled antiferromagnetically. This provides new and interesting opportunities\nfor application in spintronics and data storage and processing technologies. A\nspin valve magnetoresistance may be achieved when magnetic moments of both\natomic planes are driven to parallel alignment by an external magnetic field.\nThe resistance change associated with the transition from antiparallel to the\nparallel configuration is qualitatively similar to that observed in\nartificially layered metallic magnetic structures. Detailed electronic\nstructure of VSe$_2$ was obtained from DFT calculations. Then, the ballistic\nspin-valve magnetoresistance was determined within the Landauer formalism. In\naddition, we also analyze thermal and thermoelectric properties. Both phases of\nVSe$_2$, denoted as H and T, are considered.",
        "positive": "Phase-field study on the segregation mechanism of Cr to lamellar\n  interface in C40-NbSi2/C11b-MoSi2 duplex silicide: Cr-segregation to a lamellar interface in NbSi2/MoSi2 duplex silicide has\nbeen examined by a newly developed phase-field model. The model can take into\naccount the segregation energy evaluated by a first principles calculation to\nreflect the chemical interaction between solute atoms and the interface in\naddition to the elastic interaction. Cr segregation occurs at the interface in\nthe case with segregation energy whereas no segregation occurs in the case with\nonly elastic interaction. However, the segregation is much smaller than that\nobserved in the experiment when the segregation energy was evaluated by the\nfirst principles calculation without lattice vibration (i.e. for 0 K). Another\nsimulations with the segregation energy with lattice vibration results in\nsegregation comparable to that in the experiment. Thus, it has been revealed\nthat the solute-interface chemical interaction and its temperature dependence\nis responsible for the interfacial segregation of Cr."
    },
    {
        "anchor": "A non-perturbative theory of effective Hamiltonians: example of moir\u00e9\n  materials: We demonstrate that there exists a continuum Hamiltonian $H(\\bf{r},\\bf{p})$\nthat is formally the operator equivalent of the general tight-binding method,\ninheriting the associativity and Hermiticity of the latter operator. This\nprovides a powerful and controlled method of obtaining effective Hamiltonians\nvia Taylor expansion with respect to momentum and, optionally, deformation\nfields. In particular, for fundamentally non-perturbative defects, such as\ntwist faults and partial dislocations, the method allows the deformation field\nto be retained to all orders, providing an efficient scheme for the generation\nof transparent and compact Hamiltonians for such defects. We apply the method\nto a survey of incommensurate physics in twist bilayers of graphene,\ngraphdiyne, MoS$_2$, and phosphorene. For graphene we are able to reproduce the\n`reflected Dirac cones' of the $30^\\circ$ quasi-crystalline bilayer found in a\nrecent ARPES experiment, and show it is an example of a more general phenomena\nof coupling by the moir\\'e momentum. We show that incommensurate physics is\ngoverned by the decay of the interlayer interaction on the scale of the single\nlayer reciprocal lattices, and demonstrate that if this is slow incommensurate\nscattering effects lead to very rapid broadening of band manifolds as the twist\nangle is tuned through commensurate values.",
        "positive": "Oxide layer dependent orbital torque efficiency in ferromagnet/Cu/Oxide\n  heterostructures: The utilization of orbital transport provides a versatile and efficient spin\nmanipulation mechanism. As interest in orbital-mediated spin manipulation\ngrows, we face a new issue to identify the underlying physics that determines\nthe efficiency of orbital torque (OT). In this study, we systematically\ninvestigate the variation of OT governed by orbital Rashba-Edelstein effect at\nthe Cu/Oxide interface, as we change the Oxide material. We find that OT varies\nby a factor of ~2, depending on the Oxide. Our results suggest that the active\nelectronic interatomic interaction (hopping) between Cu and oxygen atom is\ncritical in determining OT. This also gives us an idea of what type of material\nfactors is critical in forming a chiral orbital Rashba texture at the Cu/Oxide\ninterface."
    },
    {
        "anchor": "A Novel Isomer of Volleyballene Sc$_{20}$C$_{60}$: The Stone-Wales defect is a well-known and significant defective structure in\ncarbon materials, impacting their mechanical, chemical, and electronic\nproperties. Recently, a novel metal-carbon nanomaterial named Volleyballene has\nbeen discovered, characterized by a C-C bond bridging two carbon pentagons.\nUsing first-principles calculations, a stable Stone-Wales-defective counterpart\nof Volleyballene, exhibiting $T_h$ symmetry, has been proposed by rotating the\nC-C bond by 90${\\deg}$. Although its binding energy per atom is slightly higher\nthan Volleyballene (${\\Delta}E_b$ = 0.009 eV/atom), implying marginally lower\nstructural stability, it can maintain its bond structure until the effective\ntemperature reaches about 1538.56 K, indicating greater thermodynamic\nstability. Additionally, its highest vibration frequency is 1346.2 cm$^{-1}$,\nindicating strong chemical bond strength. A theoretical analysis of the\nSc$_{20}$C$_{60}$+Sc$_{20}$C$_{60}$ binary systems highlights that the stable\nbuilding block may be applied in potential nano-assembly.",
        "positive": "Ultrafast Magnetic Switching of GdFeCo with Electronic Heat Currents: We report the magnetic response of Au/GdFeCo bilayers to optical irradiation\nof the Au surface. For bilayers with Au thickness greater than 50 nm, the great\nmajority of energy is absorbed by the Au electrons, creating an initial\ntemperature differential of thousands of Kelvin between the Au and GdFeCo\nlayers. The resulting electronic heat currents between the Au and GdFeCo layers\nlast for several picoseconds with energy flux in excess of 2 TW m-2, and\nprovide sufficient heating to the GdFeCo electrons to induce deterministic\nreversal of the magnetic moment."
    },
    {
        "anchor": "The definition of quasicrystals: It is argued that the definition of quasicrystals should not include the\nrequirement that they possess an axis of symmetry that is forbidden in periodic\ncrystals. The term \"quasicrystal\" should simply be regarded as an abbreviation\nfor \"quasiperiodic crystal,\" possibly with two provisos, as discussed below.\nThe argument is supported by theoretical as well as experimental examples of\nquasicrystals without any forbidden symmetry.",
        "positive": "Study of single crystalline SrAgSb and SrAuSb semimetals: Given renewed interest in the electronic properties of semimetallic compounds\nwith varying degrees of spin orbit coupling we have grown single crystals of\nSrAgSb and SrAuSb, measured their temperature and field dependent electrical\nresistivity and magnetization and performed density functional theory (DFT)\nband structure calculations. Magnetization measurements are consistent with a\ndiamagnetic host with a small amount of local moment bearing impurities.\nAlthough the residual resistivity ratio (RRR) for all samples studied was\nrelatively low, ranging between 2.4 and 3.4, the compounds had non-saturating\nmagnetoresistance (MR), reaching values of $\\sim$ 17% and $\\sim$ 70% at 4 K and\n9 T for SrAgSb and SrAuSb respectively. Band structure calculations, using the\nexperimentally determined Wyckoff positions for the Sr, Ag/Au, and Sb atoms,\nshow that whereas SrAgSb is a topologically trivial, but compensated,\nsemimetal; SrAuSb is a topologically non-trivial, Dirac semimetal."
    },
    {
        "anchor": "Distorted wurtzite unit cells: Determination of lattice parameters of\n  non-polar a-plane AlGaN and estimation of solid phase Al content: Unlike c-plane nitrides, ``non-polar\" nitrides grown in e.g. the a-plane or\nm-plane orientation encounter anisotropic in-plane strain due to the anisotropy\nin the lattice and thermal mismatch with the substrate or buffer layer. Such\nanisotropic strain results in a distortion of the wurtzite unit cell and\ncreates difficulty in accurate determination of lattice parameters and solid\nphase group-III content (x_solid) in ternary alloys. In this paper we show that\nthe lattice distortion is orthorhombic, and outline a relatively simple\nprocedure for measurement of lattice parameters of non-polar group III-nitrides\nepilayers from high resolution x-ray diffraction measurements. We derive an\napproximate expression for x_solid taking into account the anisotropic strain.\nWe illustrate this using data for a-plane AlGaN, where we measure the lattice\nparameters and estimate the solid phase Al content, and also show that this\nmethod is applicable for m-plane structures as well.",
        "positive": "Oxygen vacancy enhanced room temperature ferromagnetism in Al-doped MgO\n  nanoparticles: We have investigated the room temperature ferromagnetic order that develops\nin Al-substituted magnesium oxide, Mg(Al)O, nanoparticles with Al fractions of\nup to 5 at.%. All samples, including undoped MgO nanoparticles, exhibit room\ntemperature ferromagnetism, with the saturation magnetization reaching a\nmaximum of 0.023 emu/g at 2 at.% of Al. X-ray photoelectron spectroscopy\nidentifies the presence of oxygen vacancies in both doped and undoped MgO\nnanoparticles, with the vacancy concentration increasing upon vacuum annealing\nof Mg(Al)O, resulting in two-fold enhancement of the saturation magnetization\nfor 2 at.% Al-doped MgO. Our results suggest that the oxygen vacancies are\nlargely responsible for room temperature ferromagnetism in MgO."
    },
    {
        "anchor": "Application of hydrogenation to low-temperature cleaning of the Si(001)\n  surface in the processes of molecular-beam epitaxy: Investigation by STM,\n  RHEED and HRTEM: Structural properties of the clean Si(001) surface obtained as a result of\nlow-temperature (470--650C) pre-growth annealings of silicon wafers in a\nmolecular-beam epitaxy chamber have been investigated. To decrease the cleaning\ntemperature, a silicon surface was hydrogenated in the process of a preliminary\nchemical treatment in HF and NH_4F aqueous solutions. It has been shown that\nsmooth surfaces composed by wide terraces separated by monoatomic steps can be\nobtained by dehydrogenation at the temperatures > 600C, whereas clean surfaces\nobtained at the temperatures < 600C are rough. It has been found that there\nexists a dependence of structural properties of clean surfaces on the\ntemperature of hydrogen thermal desorption and the process of the preliminary\nchemical treatment. The frequency of detachment/attachment of Si dimers from/to\nthe steps and effect of the Ehrlich-Schwoebel barrier on ad-dimer migration\nacross steps have been found to be the most probable factors determining a\ndegree of the resultant surface roughness.",
        "positive": "Spontaneous Ferroelectricity in Strained Low-Temperature Monoclinic\n  Fe3O4: A First-Principle Study: The spontaneous ferroelectric polarization of low-temperature monoclinic\nFe3O4 was investigated by first-principles calculations."
    },
    {
        "anchor": "Orbital selective switching of ferromagnetism in an oxide quasi\n  two-dimensional electron gas: Multi-orbital physics in quasi-two-dimensional electron gases (q2DEGs)\ntriggers unique phenomena not observed in bulk materials, such as\nunconventional superconductivity and magnetism. Here, we investigate the\nmechanism of orbital selective switching of the spin-polarization in the oxide\nq2DEG formed at the (001) interface between the LaAlO$_{3}$, EuTiO$_{3}$ and\nSrTiO$_{3}$ band insulators. By using density functional theory calculations,\ntransport, magnetic and x-ray spectroscopy measurements, we find that the\nfilling of titanium-bands with 3d$_{xz,yz}$ orbital character in the EuTiO3\nlayer and at the interface with SrTiO$_{3}$ induces an antiferromagnetic to\nferromagnetic switching of the exchange interaction between Eu-4f$^{7}$\nmagnetic moments. The results explain the observation of the carrier density\ndependent ferromagnetic correlations and anomalous Hall effect in this q2DEG,\nand demonstrate how combined theoretical and experimental approaches can lead\nto a deeper understanding of novel electronic phases and serve as a guide for\nthe materials design for advanced electronic applications.",
        "positive": "A first-principles linear response description of the spin Nernst effect: A first-principles description of the spin Nernst effect, denoting the\noccurrence of a transverse spin current due to a temperature gradient, is\npresented. The approach, based on an extension to the Kubo-Streda equation for\nspin transport, supplies in particular the formal basis for investigations of\ndiluted as well as concentrated alloys. Results for corresponding applications\nto the alloy system Au-Cu give the intrinsic and extrinsic contributions to the\nrelevant transport coefficients. Using scaling laws allows in addition to split\nthe extrinsic contribution into its skew scattering and side-jump parts."
    },
    {
        "anchor": "Probing Spin Polarization with Andreev Reflection: A Theoretical Basis: Andreev reflection at the interface between a ferromagnet and a\nsuperconductor has become a foundation of a versatile new technique of\nmeasuring the spin polarization of magnetic materials. In this paper we will\nbriefly outline a general theory of Andreev reflection for spin-polarized\nsystems and arbitrary Fermi surface in two limiting cases of ballistic and\ndiffusive transport",
        "positive": "Detection of High Energy Ionizing Radiation using Deeply Depleted\n  Graphene-Oxide-Semiconductor Junctions: Graphene's linear bandstructure and two-dimensional density of states provide\nan implicit advantage for sensing charge. Here, these advantages are leveraged\nin a deeply depleted graphene-oxide-semiconductor (D2GOS) junction detector\narchitecture to sense carriers created by ionizing radiation. Specifically, the\nroom temperature response of the silicon-based D2GOS junction is analyzed\nduring irradiation with 20 MeV Si4+ ions. Detection was demonstrated for doses\nranging from 12-1200 ions with device functionality maintained with no\nsubstantive degradation. To understand the device response, D2GOS pixels were\ncharacterized post-irradiation via a combination of electrical\ncharacterization, Raman spectroscopy, and photocurrent mapping. This combined\ncharacterization methodology underscores the lack of discernible damage caused\nby irradiation to the graphene while highlighting the nature of interactions\nbetween the incident ions and the silicon absorber."
    },
    {
        "anchor": "Neutron reflectometry on highly absorbing films and its application to\n  10B4C-based neutron detectors: Neutron reflectometry is a powerful tool used for studies of surfaces and\ninterfaces. In general the absorption in the typical studied materials can be\nneglected and this technique is limited to the measurement of the reflectivity\nonly. In the case of strongly absorbing nuclei the number of neutrons is not\nconserved and the absorption can be directly measured by using the\nneutron-induced fluorescence technique which exploits the prompt particle\nemission of absorbing isotopes. This technique is emerging from soft matter and\nbiology where highly absorbing nuclei, generally in very small quantities, are\nused as a label for buried layers. Nowadays the importance of highly absorbing\nlayers is rapidly increasing, partially because of their application in neutron\ndetection; a field that has become more and more active also due to the\n3He-shortage. In this manuscript we extend the neutron-induced fluorescence\ntechnique to the study of thick layers of highly absorbing materials; in\nparticular 10B4C. The theory of neutron reflectometry is a commonly studied\ntopic, however the subtle relationship between the reflection and the\nabsorption of neutrons is not widely known, in particular when a strong\nabsorption is present. The theory for a general stack of absorbing layers has\nbeen developed and compared to measurements. This new technique has potential\nas a tool for characterization of highly absorbing layers. We also report on\nthe requirements that a 10B4C layer must fulfill in order to be employed as a\nconverter in neutron detection.",
        "positive": "Magnetocrystalline anisotropy in YCo5 and LaCo5: A choice of correlation\n  parameters and the relativistic effects: The dependence of the magnetocrystalline anisotropy energy (MAE) of MCo5 (M =\nY, La) on the Coulomb correlations and strength of spin orbit (SO) interaction\nwithin the GGA + U scheme is investigated. A range of parameters suitable for\nthe satisfactory description of key magnetic properties is determined. The\norigin of MAE in these materials is mostly related to the large orbital moment\nanisotropy of Co atoms on the 2c crystallographic site. Dependence of\nrelativistic effects on Coulomb correlations, applicability of the second order\nperturbation theory for the description of MAE and effective screening of the\nSO interaction in these systems are discussed using a generalized virial\ntheorem."
    },
    {
        "anchor": "Microstructured tunable two dimensional potential modulation in organic\n  heterostructure field effect transistors: In this paper, two dimensional modulation of the potential in sexithiophene\n(T6) / N,N-bis(n-octyl)-dicyanoperylenediimide (PDI-8CN2) heterojunction field\neffect transistors due to the specific microstructure at the interface is used\nto explain the negative transconductance effect (NTC) experienced in\nsexithiophene (T6) / N,N-bis(n-octyl)-dicyanoperylenediimide (PDI-8CN2)\nheterojunction field effect transistors. The NTC effect has been experienced in\ntunnel devices, such as the tunnel diode, the resonant tunneling field effect\ntransistors (RT-FETs), resonant tunneling double barrier devices. In grid-gate\nmodulation-doped field effect transistors, instead, a periodic potential\nbarriers in the direction of the transport of charges was used to explain the\nnegative transconductance (NDR). Since in T6 / PDI-8CN2 heterojunction field\neffect transistors the NTC effect is irrespective of the order of the\nsemiconductor layer and since the modulation of the transport properties is\ndeeply influenced by the island dimension of the semiconductor layer, we argue\nthat the origin of the NTC effect resides in the achievement of a specific\nmicrostructure of the heterostructure in the charge transport plane.",
        "positive": "Measuring the Tensor Polarization of Positronium: A method for measuring the tensor polarization in a positronium (Ps) beam is\nproposed, which is based on the determination of the Ps lifetime as a function\nof the orientation of a homogeneous magnetic field. The dependence of the\northopositronum (o-Ps) lifetime on the angle between the directions of the\nmagnetic field and the tensor polarization of the Ps beam can be determined\nfrom the results of measurements from two or more field orientations."
    },
    {
        "anchor": "Chemical functionalization, electronic and dielectric properties of\n  hybrid organic-tin layers: Band gap tuning and dielectric properties of small organic ligands adsorbed\non tin monolayers (stanene) have been investigated using first-principles\ncalculations. Charge density analysis using density-functional theory shows\nthat the ligands are chemisorbed on stanene and some of the groups can open a\nband gap in the originally metallic statene. Furthermore many-body GW\ncalculations demonstrate that the dielectric properties of bare and ligand\nadsorbed stanene have a large anisotropy. Our findings of a finite gap opens a\npath for rational theoretical design of functionalized two-dimensional stanene.",
        "positive": "Non-equilibrium self-assembly of spin-wave solitons in FePt\n  nanoparticles: Magnetic nanoparticles such as FePt in the L10-phase are the bedrock of our\ncurrent data storage technology. As the grains become smaller to keep up with\ntechnological demands, the superparamagnetic limit calls for materials with\nhigher magneto-crystalline anisotropy. This in turn reduces the magnetic\nexchange length to just a few nanometers enabling magnetic structures to be\ninduced within the nanoparticles. Here we describe the existence of spin-wave\nsolitons, dynamic localized bound states of spin-wave excitations, in FePt\nnanoparticles. We show with time-resolved X-ray diffraction and micromagnetic\nmodeling that spin-wave solitons of sub-10 nm sizes form out of the\ndemagnetized state following femtosecond laser excitation. The measured soliton\nspin-precession frequency of 0.1 THz positions this system as a platform to\ndevelop miniature devices capable of filling the THz gap."
    },
    {
        "anchor": "Comment on \"Atomic Scale Structure and Chemical Composition across\n  Order-Disorder Interfaces\": Interfaces have long been known to be the key to many mechanical and electric\nproperties. To nickel base superalloys which have perfect creep and fatigue\nproperties and have been widely used as materials of turbine blades, interfaces\ndetermine the strengthening capacities in high temperature. By means of high\nresolution scanning transmission electron microscopy (HRSTEM) and 3D atom probe\n(3DAP) tomography, Srinivasan et al. proposed a new point that in nickel base\nsuperalloys there exist two different interfacial widths across the\n{\\gamma}/{\\gamma}' interface, one corresponding to an order-disorder\ntransition, and the other to the composition transition. We argue about this\nconclusion in this comment.",
        "positive": "Chemical order in Ge-Ga-Sb-Se glasses: The short range order in Ge$_{30}$Ga$_{5}$Sb$_{10}$Se$_{55}$ and\nGe$_{21}$Ga$_{5}$Sb$_{10}$Se$_{64}$ glasses was investigated by X-ray (XRD) and\nneutron diffraction (ND) as well as extended X-ray absorption fine structure\n(EXAFS) measurements at the Ge, Ga, Sb and Se K-edges. Large scale structural\nmodels were obtained by fitting simultaneously the experimental data sets by\nreverse Monte Carlo (RMC) simulation technique. It was found that Ge, Sb and Se\natoms follow the Mott-rule and have 4, 3 and 2 nearest neighbors, respectively.\nThe average coordination number of the Ga atoms was around 4. The structure of\nthese glasses can be described by the chemically ordered network model: the\nGe-Se, Ga-Se and Sb-Se bonds are the most prominent while Ge-Ge and Ge-Sb bonds\nare formed only in Se-poor compositions. Models generated by RMC contained some\nlong distances (0.3-0.4 {\\AA} higher than the usual covalent bond lengths)\nbetween Ge-Se and/or Ge-Ge pairs. Dedicated simulation runs confirm the\nexistence of these bonds."
    },
    {
        "anchor": "Nonlinear sub-switching regime of magnetization dynamics in\n  photo-magnetic garnets: We analyze, both experimentally and numerically, the nonlinear regime of the\nphoto-induced coherent magnetization dynamics in cobalt-doped yttrium iron\ngarnet films. Photo-magnetic excitation with femtosecond laser pulses reveals a\nstrongly nonlinear response of the spin subsystem with a significant increase\nof the effective Gilbert damping. By varying both laser fluence and the\nexternal magnetic field, we show that this nonlinearity originates in the\nanharmonicity of the magnetic energy landscape. We numerically map the\nparameter workspace for the nonlinear photo-induced spin dynamics below the\nphoto-magnetic switching threshold. Corroborated by numerical simulations of\nthe Landau-Lifshitz-Gilbert equation, our results highlight the key role of the\ncubic symmetry of the magnetic subsystem in reaching the nonlinear spin\nprecession regime. These findings expand the fundamental understanding of\nlaser-induced nonlinear spin dynamics as well as facilitate the development of\napplied photo-magnetism.",
        "positive": "Effect of Dy substitution in the giant magnetocaloric properties of\n  HoB$_{2}$: Recently, a massive magnetocaloric effect near the liquefaction temperature\nof hydrogen has been reported in the ferromagnetic material HoB$_{2}$. Here we\ninvestigate the effects of Dy substitution in the magnetocaloric properties of\nHo$_{1-x}$Dy$_{x}$B$_{2}$ alloys ($\\textit{x}$ = 0, 0.3, 0.5, 0.7, 1.0). We\nfind that the Curie temperature ($\\textit{T}$$_{C}$) gradually increases upon\nDy substitution, while the magnitude of the magnetic entropy change |$\\Delta\n\\textit{S}_{M}$| at $\\textit{T}$ = $\\textit{T}_{C}$ decreases from 0.35 to 0.15\nJ cm$^{-3}$ K$^{-1}$ for a field change of 5 T. Due to the presence of two\nmagnetic transitions in these alloys, despite the change in the peak magnitude\nof |$\\Delta \\textit{S}_{M}$|, the refrigerant capacity ($\\textit{RC}$) and\nrefrigerant cooling power ($\\textit{RCP}$) remains almost constant in all\ndoping range, which as large as 5.5 J cm$^{-3}$ and 7.0 J cm$^{-3}$ for a field\nchange of 5 T. These results imply that this series of alloys could be an\nexciting candidate for magnetic refrigeration in the temperature range between\n10-50 K."
    },
    {
        "anchor": "Surface and Bulk Relaxation of Vapour-Deposited Polystyrene Glasses: We have studied the liquid-like response of the surface of vapour-deposited\nglassy films of polystyrene to the introduction of gold nanoparticles on the\nsurface. The build-up of polymer material was measured as a function of time\nand temperature for both as-deposited films, as well as films that have been\nrejuvenated to become normal glasses cooled from the equilibrium liquid. The\ntemporal evolution of the surface profile is well described by the\ncharacteristic power law of capillary-driven surface flows. In all cases, the\nsurface evolution of the as-deposited films and the rejuvenated films are\nenhanced compared to bulk and are not easily distinguishable from each other.\nThe temperature dependence of the measured relaxation times determined from the\nsurface evolution is found to be quantitatively comparable to similar studies\nfor high molecular weight spincast polystyrene. Comparisons to numerical\nsolutions of the glassy thin film equation provide quantitative estimates of\nthe surface mobility. For temperatures sufficiently close to the\nglass-transition temperature, particle embedding is also measured and used as a\nprobe of bulk dynamics, and in particular bulk viscosity.",
        "positive": "Violation of the `Zero-Force Theorem' in the time-dependent\n  Krieger-Li-Iafrate approximation: We demonstrate that the time-dependent Krieger-Li-Iafrate approximation in\ncombination with the exchange-only functional violates the `Zero-Force\nTheorem'. By analyzing the time-dependent dipole moment of Na5 and Na9+, we\nfurthermore show that this can lead to an unphysical self-excitation of the\nsystem depending on the system properties and the excitation strength.\nAnalytical aspects, especially the connection between the `Zero-Force Theorem'\nand the `Generalized-Translation Invariance' of the potential, are discussed."
    },
    {
        "anchor": "Density Functional Theory versus the Hartree Fock Method: Comparative\n  Assessment: We compare two different approaches to investigations of many-electron\nsystems. The first is the Hartree-Fock (HF) method and the second is the\nDensity Functional Theory (DFT). Overview of the main features and peculiar\nproperties of the HF method are presented. A way to realize the HF method\nwithin the Kohn-Sham (KS) approach of the DFT is discussed. We show that this\nis impossible without including a specific correlation energy, which is defined\nby the difference between the sum of the kinetic and exchange energies of a\nsystem considered within KS and HF, respectively. It is the nonlocal exchange\npotential entering the HF equations that generates this correlation energy. We\nshow that the total correlation energy of a finite electron system, which has\nto include this correlation energy, cannot be obtained from considerations of\nuniform electron systems. The single-particle excitation spectrum of\nmany-electron systems is related to the eigenvalues of the corresponding KS\nequations. We demonstrate that this spectrum does not coincide in general with\nthe eigenvalues of KS or HF equations.",
        "positive": "Carbon release by selective alloying of transition metal carbides: We have performed first principles density functional theory calculations on\nTiC alloyed on the Ti sublattice with 3d transition metals ranging from Sc to\nZn. The theory is accompanied with experimental investigations, both as regards\nmaterials synthesis as well as characterization. Our results show that by\ndissolving a metal with a weak ability to form carbides, the stability of the\nalloy is lowered and a driving force for the release of carbon from the carbide\nis created. During thin film growth of a metal carbide this effect will favor\nthe formation of a nanocomposite with carbide grains in a carbon matrix. The\nchoice of alloying elements as well as their concentrations will affect the\nrelative amount of carbon in the carbide and in the carbon matrix. This can be\nused to design the structure of nanocomposites and their physical and chemical\nproperties. One example of applications is as low-friction coatings. Of the\nmaterials studied, we suggest the late 3d transition metals as the most\npromising elements for this phenomenon, at least when alloying with TiC."
    },
    {
        "anchor": "Translational and rotational mode coupling in disordered ferroelectric\n  KTa(1-x)Nb(x)O(3) studied by Raman spectroscopy: The coupling of translational modes to the reorientational motion is an\nessential property of systems with internal orientational degrees of freedom.\nDue to their high complexity most of those systems (molecular crystals,\nglasses...) present a major puzzle for scientists. In this paper we analyze the\nRaman scattering of a relatively simple ferroelectric system,\nKTa(1-x)Nb(x)O(3), which may serve as a model for more complicated cases. We\nare showing that there is a strong coupling between translational and\nreorientational motion in the crystal. Our data suggest that this coupling is\nthe main reason for the depolarized component of the second order Raman spectra\nand that it is also responsible for lowering of the frequency (softening) of\nthe transverse acoustic mode down to the third of three transitions, below\nwhich reorientational motion is no longer allowed.",
        "positive": "Strain induced metal-insulator transition in ultrathin films of\n  SrRuO$_3$: The ultrathin film limit has been shown to be a rich playground for unusual\nlow dimensional physics. Taking the example of SrRuO$_3$ which is ferromagnetic\nand metallic at the bulk limit, one finds that it becomes antiferromagnetic and\ninsulating at the three monolayers limit when grown on SrTiO$_3$. The origin of\nthe insulating state is traced to strongly orbital dependent exchange\nsplittings. A modest compressive strain of 1% of the SrTiO$_3$ substrate is\nthen found to drive the system into a highly confined two-dimensional 100% spin\npolarized metallic state. This metal-insulator transition driven by a modest\nstrain could be useful in two state device applications."
    },
    {
        "anchor": "Lattice dynamics study of electron-correlation-induced charge density\n  wave in antiferromagnetic kagome metal FeGe: Electron-correlation-driven phonon soft modes have been recently reported in\nthe antiferromagnetic kagome FeGe compound and associated with the observed\ncharge density wave (CDW). In this paper, we present a systematic investigation\nof the CDW origin in the context of the ab initio lattice dynamics study.\nPerforming the group theory analysis of the mentioned soft mode, we found that\nthe stable structure has the Immm symmetry and can be achieved by the small\nshift of Ge atoms. Additionally, we show that the final structure realizes a\ndistorted honeycomb Ge lattice as well as a non-flat kagome-like Fe net. For\ncompleteness, we present the electronic properties calculations. From the\ntheoretical STM topography simulation, we indicate that the observed CDW occurs\nin the deformed honeycomb Ge sublattice.",
        "positive": "Formation of solid-state dendrites under the influence of coherency\n  stresses: A diffuse interface approach: In this paper, we have formulated a phase-field model based on the\ngrand-potential functional for the simulation of precipitate growth in the\npresence of coherency stresses. In particular, we study the development of\ndendrite-like patterns arising out of diffusive instabilities during the growth\nof a precipitate in a supersaturated matrix. Here, we characterize the role of\nelastic energy anisotropy and its strength on the selection of a dendrite tip\nradius and velocity. We find that there is no selection of a unique tip shape\nas observed in the case of solidification, and the selection constant\n$\\sigma^{*}=2d_0D/R_{tip}^{2}V_{tip}$ increases linearly with simulation time\nfor all the simulation conditions (where $R_{tip}$ and $V_{tip}$ are the tip\nradius and velocity). Therefore, structures derived in solid-state in the\npresence of elastic anisotropy may only be referred to as dendrite-like."
    },
    {
        "anchor": "Observation and enhancement of room temperature bilinear magnetoelectric\n  resistance in sputtered topological semimetal Pt3Sn: Topological semimetal materials have become a research hotspot due to their\nintrinsic strong spin-orbit coupling which leads to large charge-to-spin\nconversion efficiency and novel transport behaviors. In this work, we have\nobserved a bilinear magnetoelectric resistance (BMER) of up to 0.1 nm2A-1Oe-1\nin a singlelayer of sputtered semimetal Pt3Sn at room temperature. Different\nfrom previous observations, the value of BMER in sputtered Pt3Sn does not\nchange out-of-plane due to the polycrystalline nature of Pt3Sn. The observation\nof BMER provides strong evidence of the existence of spin-momentum locking in\nthe sputtered polycrystalline Pt3Sn. By adding an adjacent CoFeB magnetic\nlayer, the BMER value of this bilayer system is doubled compared to the single\nPt3Sn layer. This work broadens the material system in BMER study, which paves\nthe way for the characterization of topological states and applications for\nspin memory and logic devices.",
        "positive": "Oxygen stoichiometry, crystal structure, and magnetism in\n  La$_{0.5}$Sr$_{0.5}$CoO$_{3-\u03b4}$: We have prepared a series of polycrystalline samples\nLa$_{0.5}$Sr$_{0.5}$CoO$_{3-\\delta}$} with $0 < \\delta \\le 0.21$ and\ncharacterized their oxygen content, crystal structure, and magnetic properties.\nWhile the fully oxygenated samples are good ferromagnets, samples with larger\n$\\delta$ values display increasingly broad magnetic transitions. The saturation\nmagnetization at 5 K falls rapidly as $\\delta$ increases. First principles\nelectronic structure calculations provide insights into the magnetic behavior\nof the fully oxygenated compound, and the manner in which ferromagnetic\nordering is affected by increasing oxygen non-stoichiometry."
    },
    {
        "anchor": "Induced Work Function Changes at Mg-doped MgO/Ag(001) Interfaces: a\n  Combined Auger Electron Diffraction and Density Functional Study: The properties of MgO/Ag(001) ultrathin films with substitutional Mg atoms in\nthe interface metal layer have been investigated by means of Auger electron\ndiffraction experiments, ultraviolet photoemission spectroscopy, and density\nfunctional theory (DFT) calculations. Exploiting the layer-by-layer resolution\nof the Mg KL_23 L_23 Auger spectra and using multiple scattering calculations,\nwe first determine the interlayer distances as well as the morphological\nparameters of the MgO/Ag(001) system with and without Mg atoms incorporated at\nthe interface. We find that the Mg atoms incorporation drives a strong\ndistortion of the interface layers and that its impact on the metal/oxide\nelectronic structure is an important reduction of the work function (0.5 eV)\nrelated to band-offset variations at the interface. These experimental\nobservations are in very good agreement with our DFT calculations which\nreproduce the induced lattice distortion and which reveal (through a Bader\nanalysis) that the increase of the interface Mg concentration results in an\nelectron transfer from Mg to Ag atoms of the metallic interface layer. Although\nthe local lattice distortion appears as a consequence of the attractive\n(repulsive) Coulomb interaction between O2- ions of the MgO interface layer and\nthe nearest positively (negatively) charged Mg (Ag) neighbors of the metallic\ninterface layer, its effect on the work function reduction is only limited.\nFinally, an analysis of the induced work function changes in terms of charge\ntransfer, rumpling, and electrostatic compression contributions is attempted\nand reveals that the metal/oxide work function changes induced by interface Mg\natoms incorporation are essentially driven by the increase of the electrostatic\ncompression effect.",
        "positive": "Tunable spin Hall and spin Nernst effects in Dirac line-node semimetals\n  XCuYAs (X=Zr, Hf; Y=Si, Ge): The quaternary arsenide compounds XCuYAs (X=Zr, Hf; Y= Si, Ge) belong to the\nvast family of the 1111-type quaternary compounds, which possess outstanding\nphysical properties ranging from $p$-type transparent semiconductors to\nhigh-temperature Fe-based superconductors. In this paper, we study the\nelectronic structure topology, spin Hall effect (SHE) and spin Nernst effect\n(SNE) in these compounds based on density functional theory calculations. First\nwe find that the four considered compounds are Dirac semimetals with the\nnonsymmorphic symmetry-protected Dirac line nodes along the Brillouin zone\nboundary $A$-$M$ and $X$-$R$ and low density of states (DOS) near the Fermi\nlevel ($E_F$). Second, the intrinsic SHE and SNE in some of these considered\ncompounds are found to be large. In particular, the calculated spin Hall\nconductivity (SHC) of HfCuGeAs is as large as -514 ($\\hbar$/e)(S/cm). The spin\nNernst conductivity (SNC) of HfCuGeAs at room temperature is also large, being\n-0.73 ($\\hbar$/e)(A/m-K). Moreover, both the magnitude and sign of the SHC and\nSNC in these compounds can be manipulated by varying either the applied\nelectric field direction or spin current direction. The SHE and SNE in these\ncompounds can also be enhanced by tuning the Fermi level via chemical doping or\nelectric gating. Finally, a detailed analysis of the band-decomposed and\n$k$-resolved spin Berry curvatures reveals that these large SHC and SNC as well\nas their notable tunabilities originate largely from the presence of a large\nnumber of spin-orbit coupling-gapped Dirac points near the Fermi level as well\nas the gapless Dirac line-nodes, which give rise to large spin Berry\ncurvatures. Our findings thus suggest that the four XCuYAs compounds not only\nprovide a valuable platform for exploring the interplay between SHE, SNE and\nband topology but also have promising applications in spintronics and spin\ncaloritronics."
    },
    {
        "anchor": "The Quadruplon in a Monolayer Semiconductor: So far, composite particles involving two or three constituent particles have\nbeen experimentally identified, such as the Cooper pairs, excitons, and trions\nin condensed matter physics, or diquarks and mesons in quantum chromodynamics.\nAlthough the four-body irreducible entities have long been predicted\ntheoretically in a variety of physical systems alternatively as quadruplons,\nquadrons, or quartets, the closely related experimental observation so far\nseems to be restricted to the field of elementary particles (e.g. the recent\ntetraquark at CERN). In this article, we present the first experimental\nevidence for the existence of a four-body irreducible entity, the quadruplon,\ninvolving two electrons and two holes in a monolayer of Molybdenum Ditelluride.\nUsing the optical pump-probe technique, we discovered a series of new spectral\nfeatures that are distinct from those of trions and bi-excitons. By solving the\nfour-body Bethe-Salpeter equation in conjunction with the cluster expansion\napproach, we are able to explain these spectral features in terms of the\nfour-body irreducible cluster or the quadruplons. In contrast to a bi-exciton\nwhich consists of two weakly bound excitons, a quadruplon consists of two\nelectrons and two holes without the presence of an exciton. Our results provide\nexperimental evidences of the hitherto theorized four-body entities and thus\ncould impact the understanding of the structure of matter in a wide range of\nphysical systems or new semiconductor technologies.",
        "positive": "Purely rotational symmetry-protected topological crystalline insulator\n  $\u03b1$-Bi4Br4: Recent theoretical advances have proposed a new class of topological\ncrystalline insulator (TCI) phases protected by rotational symmetries. Distinct\nfrom topological insulators (TIs), rotational symmetry-protected TCIs are\nexpected to show unique topologically protected boundary modes: First, the\nsurface normal to the rotational axis features unpinned Dirac surface states\nwhose Dirac points are located at generic k points. Second, due to the\nhigher-order bulk boundary correspondence, a 3D TCI also supports 1D helical\nedge states. Despite the unique topological electronic properties, to date,\npurely rotational symmetry-protected TCIs remain elusive in real materials.\nUsing first-principles band calculations and theoretical modeling, we identify\nthe van der Waals material $\\alpha$-Bi4Br4 as a TCI purely protected by\nrotation symmetry. We show that the Bi4Br4's (010) surface exhibits a pair of\nunpinned topological Dirac fermions protected by the two-fold rotational axis.\nThese unpinned Dirac fermions show an exotic spin texture highly favorable for\nspin transport and a band structure consisting of van Hove singularities due to\nLifshitz transition. We also identify 1D topological hinge states along the\nedges of an $\\alpha$-Bi4Br4 rod. We further discuss how the proposed\ntopological electronic properties in $\\alpha$-Bi4Br4 can be observed by various\nexperimental techniques."
    },
    {
        "anchor": "Lattice dynamics study in PbWO4 under high pressure: Room-temperature Raman scattering has been measured in lead tungstate up to\n17 GPa. We report the pressure dependence of all the Raman modes of the\ntetragonal scheelite phase (PbWO4-I, space group I41/a), which is stable at\nambient conditions. Upon compression the Raman spectrum undergoes significant\nchanges around 6.2 GPa due to the onset of a partial structural phase\ntransition to the monoclinic PbWO4-III phase (space group P21/n). Further\nchanges in the spectrum occur at 7.9 GPa, related to a scheelite-to-fergusonite\ntransition. This transition is observed due to the sluggishness and kinetic\nhindrance of the I-to-III transition. Consequently, we found the coexistence of\nthe scheelite, PbWO4-III, and fergusonite phases from 7.9 to 9 GPa, and of the\nlast two phases up to 14.6 GPa. Further to the experiments, we have performed\nab initio lattice dynamics calculations which have greatly helped us in\nassigning the Raman modes of the three phases and discussing their pressure\ndependence.",
        "positive": "Growth and characterization of heteroepitaxial La-substituted BaSnO$_3$\n  films on SrTiO$_3$ (001) and SmScO$_3$ (110) substrates: Heteroepitaxial growth of BaSnO$_3$ (BSO) and Ba$_{1-x}$La$_x$SnO$_3$ (x = 7\n%) (LBSO) thin films on different perovskite single crystal (SrTiO$_3$ (001)\nand SmScO$_3$ (110)) substrates has been achieved by Pulsed Laser Deposition\n(PLD) under optimized deposition conditions. X-ray diffraction measurements\nindicate that the films on either of these substrates are relaxed due to the\nlarge mismatch and present a high degree of crystallinity with narrow rocking\ncurves and smooth surface morphology while analytical quantification by proton\ninduced x-ray emission (PIXE) confirms the stoichiometric La transfer from a\npolyphasic target, producing films with La contents above the bulk solubility\nlimit. The films show degenerate semiconducting behavior on both substrates,\nwith the observed room temperature resistivities, Hall mobilities and carrier\nconcentrations of 4.4 $m \\Omega cm$, 10.11 $cm^2 V^{-1} s^{-1}$, and 1.38\n$\\cdot 10^{20} cm^{-3}$ on SmScO$_3$ and 7.8 $m \\Omega cm$, 5.8 $cm^2 V^{-1}\ns^{-1}$, and 1.36 $\\cdot 10^{20} cm^{-3}$ on SrTiO$_3$ ruling out any extrinsic\ncontribution from the substrate. The superior electrical properties observed on\nthe SmScO3 substrate are attributed to reduction in dislocation density from\nthe lower lattice mismatch."
    },
    {
        "anchor": "Investigation of lattice dynamics, magnetism and electronic transport in\n  $\u03b2$-Na$_{0.33}$V$_2$O$_{5}$: We investigate the electronic and magnetic properties as well as lattice\ndynamics and spin-phonon coupling of $\\beta$-Na$_{0.33}$V$_2$O$_5$ using\ntemperature-dependent Raman scattering, dc-magnetization and dc-resistivity,\nx-ray photoemission, and absorption spectroscopy. The Rietveld refinement of\nXRD pattern with space group C2/m confirms the monoclinic structure. The\nanalysis of temperature-dependent Raman spectra in a temperature range of\n13--673~K reveals an anharmonic dependence of the phonon frequency and full\nwidth at half maximum, which is accredited to the symmetric phonon decay.\nHowever, below about 40 K, the hardening of the phonon frequency beyond\nanharmonicity is attributed to the spin-phonon coupling. Interestingly, the\nestimated effective magnetic moment $\\mu_{\\rm eff}=$ 0.63~$\\mu_B$ from the\nmagnetization data manifests a mixed-valence state of V ions in 4+ (18$\\pm$1\\%)\nand 5+ (82$\\pm$1\\%). A similar ratio of V$^{4+}$ to V$^{5+}$ is also observed\nin the x-ray photoemission and x-ray absorption near-edge spectra and that is\nfound to be consistent with the sample stoichiometry. In addition, the V$^{4+}$\nions are distributed between different vanadium (V1 and V3) sites. The analysis\nof extended x-ray absorption fine structure at different V-sites gives the\ncorresponding V--O bond lengths, which are utilized in the assignment of Raman\nmodes. Moreover, the temperature-dependent resistivity resembles a\nsemiconducting behavior where the charge carrier transport is facilitated by\nthe band conduction at higher temperatures and via hopping $\\le$260~K.",
        "positive": "Parameter-free quantitative simulation of high dose microstructure and\n  hydrogen retention in ion-irradiated tungsten: Hydrogen isotopes are retained in materials for fusion power applications,\nchanging both hydrogen embrittlement and tritium inventory as the\nmicrostructure undergoes irradiation damage. But modelling of highly damaged\nmaterials - exposed to over 0.1 displacements per atom (dpa) - where asymptotic\nsaturation is observed, for example tungsten facing the plasma in a fusion\ntokamak reactor, is difficult because a highly damaged microstructure cannot be\ntreated as weakly interacting isolated defect traps. In this paper we develop\ncomputational techniques to find the defect content in highly irradiated\nmaterials without adjustable parameters. First we show how to generate\nconverged high dose (>1 dpa) microstructures using a combination of the\ncreation-relaxation algorithm and molecular dynamics simulations of collision\ncascades. Then we make robust estimates of point defects and void regions with\nsimple developments of the Wigner-Seitz decomposition of lattice sites. We use\nour estimates of the void surface area to predict the deuterium retention\ncapacity of tungsten as a function of dose. This is then compared to 3He\nnuclear reaction analysis (NRA) measurements of tungsten samples\nself-irradiated at 290 K to different damage doses and exposed to deuterium\nplasma at low energy at 370 K. We show that our simulated microstructures give\nan excellent match to the experimental data, with both model and experiment\nshowing 1.5-2.0 at.% deuterium retained in tungsten in the limit of high dose."
    },
    {
        "anchor": "3-D off-center Li+ rotors in alkali halides: solving for the eigenvalue\n  problem: We are dealing with the long-standing problem of the eigenstates and\neigenvalues of 3-D rotators by off-center impurity ions in alkali halides. The\nion runs along the brim of a sombrero-like vibronic potential. The\nquantum-mechanical motion depending on two angular coordinates, we consider the\nmotion along theta at averaged phi, and vice versa. We find the off-center ion\nperforming two rotations: one in (x,y) plane along the azimuth phi and another\none along the position angle theta, respectively, which are both described as\nMathieu's non-linear oscillators. The motion along z is complemented by an\nanharmonic vibrational mode.",
        "positive": "Influence of temperature on the displacement threshold energy in\n  graphene: The atomic structure of nanomaterials is often studied using transmission\nelectron microscopy. In addition to image formation, the energetic electrons\nmay also cause damage while impinging on the sample. In a good conductor such\nas graphene the damage is limited to the knock-on process caused by elastic\nelectron-nucleus collisions. This process is determined by the kinetic energy\nan atom needs to be sputtered, ie, its displacement threshold energy. This is\ntypically assumed to have a fixed value for all electron impacts on equivalent\natoms within a crystal. Here we show using density functional tight-binding\nsimulations that the displacement threshold energy is affected by the thermal\nperturbation of the atoms from their equilibrium positions. We show that this\ncan be accounted for in the estimation of the displacement cross section by\nreplacing the constant threshold value with a distribution. The improved model\nbetter describes previous precision measurements of graphene knock-on damage,\nand should be considered also for other low-dimensional materials."
    },
    {
        "anchor": "Reversal modes in arrays of interacting magnetic Ni nanowires: Monte\n  Carlo simulations and scaling technique: The effect of dipolar interactions in hexagonal arrays of Ni nanowires has\nbeen investigated by means of Monte Carlo simulations combined with a scaling\ntechnique, which allows the investigation of the internal structure of the\nwires. A strong dependence of the coercivity and remanence on the distance\nbetween wires has been observed. At intermediate packing densities the\ncoercivity exhibits a maximum, higher than the non-interacting value. This\nbehavior, experimentally observed, has been explained on grounds of the\ninterwire dipolar interactions. Also, different reversal modes of the\nmagnetization have been identified.",
        "positive": "Fluctuating surface-current formulation of radiative heat transfer:\n  theory and applications: We describe a novel fluctuating-surface current formulation of radiative heat\ntransfer between bodies of arbitrary shape that exploits efficient and\nsophisticated techniques from the surface-integral-equation formulation of\nclassical electromagnetic scattering. Unlike previous approaches to\nnon-equilibrium fluctuations that involve scattering matrices---relating\n\"incoming\" and \"outgoing\" waves from each body---our approach is formulated in\nterms of \"unknown\" surface currents, laying at the surfaces of the bodies, that\nneed not satisfy any wave equation. We show that our formulation can be applied\nas a spectral method to obtain fast-converging semi-analytical formulas in\nhigh-symmetry geometries using specialized spectral bases that conform to the\nsurfaces of the bodies (e.g. Fourier series for planar bodies or spherical\nharmonics for spherical bodies), and can also be employed as a numerical method\nby exploiting the generality of surface meshes/grids to obtain results in more\ncomplicated geometries (e.g. interleaved bodies as well as bodies with sharp\ncorners). In particular, our formalism allows direct application of the\nboundary-element method, a robust and powerful numerical implementation of the\nsurface-integral formulation of classical electromagnetism, which we use to\nobtain results in new geometries, including the heat transfer between finite\nslabs, cylinders, and cones."
    },
    {
        "anchor": "Sensitivity of Ag/Al Interface Specific Resistances to Interfacial\n  Intermixing: We have measured an Ag/Al interface specific resistance, 2AR(Ag/Al)(111) =\n1.4 fOhm-m^2, that is twice that predicted for a perfect interface, 50% larger\nthan for a 2 ML 50%-50% alloy, and even larger than our newly predicted 1.3\nfOhmm^2 for a 4 ML 50%-50% alloy. Such a large value of 2ARAg/Al(111) confirms\na predicted sensitivity to interfacial disorder and suggests an interface\ngreater than or equal to 4 ML thick. From our calculations, a predicted\nanisotropy ratio, 2AR(Ag/Al)(001)/2AR(Ag/Al)(111), of more then 4 for a perfect\ninterface, should be reduced to less than 2 for a 4 ML interface, making it\nharder to detect any such anisotropy.",
        "positive": "Spontaneous photo-generated carrier separation of SnO/BiOX (X=Cl, Br, I)\n  bilayer under visible light irradiation for water splitting: Alloying in 2D materials plays a more and more important role due to wide\nrange bandgap tunability and integrating the advantages of HER and OER. Here,\nthe novel bilayers of SnO/BiOX (X= Cl, Br and I) bilayer are constructed to\nintegrate the advantages of narrow bandgap and separating photo-generated\ncarriers. The bandgap of the bilayers can be tuned from 1.09 to 1.84 eV,\nremarkably improving the utilization of solar energy. The large difference in\neffective masses and built-in electric field effectively hamper the fast\nrecombination of photo-generated carries, which highly enhances the\nphotocatalytic efficiency. Besides that, the type-II band alignment guarantee\nthe two half reactions could occur at different surfaces. Moreover, the optical\nabsorption (the strong transition between band edges and high joint density of\nstates) and band-edge level further confirm the SnO/BiOX (X= Cl and Br) bilayer\nis a promising candidate for overall water-splitting."
    },
    {
        "anchor": "Anisometric mesoscale nuclear and magnetic texture in sintered Nd-Fe-B\n  magnets: By means of temperature and wavelength-dependent small-angle neutron\nscattering (SANS) experiments on sintered isotropic and textured Nd-Fe-B\nmagnets we provide evidence for the existence of an anisometric structure in\nthe microstructure of the textured magnets. This conclusion is reached by\nobserving a characteristic cross-shaped angular anisotropy in the total\nunpolarized SANS cross section at temperatures well above the Curie\ntemperature. Comparison of the experimental SANS data to a microstructural\nmodel based on the superquadrics form factor allows us to estimate the shape\nand lower bounds for the size of the structure. Subtraction of the scattering\ncross section in the paramagnetic regime from data taken at room temperature\nprovides the magnetic SANS cross section. Surprisingly, the anisotropy of the\nmagnetic scattering is very similar to the nuclear SANS signal, suggesting that\nthe nuclear structure is decorated by the magnetic moments via spin-orbit\ncoupling. Based on the computation of the two-dimensional correlation function\nwe estimate lower bounds for the longitudinal and transversal magnetic\ncorrelation lengths.",
        "positive": "A crystallographic model of the {557} habit planes in low-carbon\n  martensitic steels: Low-alloy steels are constituted of twenty-four variants of lath martensite\nthat exhibit gradients of orientations from Kurdjumov-Sachs (KS) to\nNishiyama-Wassermann (NW). They are structured into four packets on each of the\ncommon close-packed plane {111}fcc// {110}bcc; and each packet is composed of\nthree blocks constituted by pairs of low-misoriented variants. The habit planes\nreported in literature for this type of martensite are {557}fcc, but it is not\nclear whether they correspond to the laths or to the blocks. In this paper, we\npresent crystallographic calculations proving that the average of the two KS\ndistortions associated with the variants in a block is exactly a NW distortion.\nA new method of averaging distortion matrices was introduced for this purpose.\nIt is also shown that the {575}fcc planes are let untilted by this NW\ndistortion, and are thus good theoretical candidates for the observed habit\nplanes. The predicted {575}fcc planes, however, do not contain any of the\ncommon close-packed directions of the two variants in the block, which is in\napparent contradiction with the current view. In order to clarify this point,\nsome Electron BackScatter Diffraction (EBSD) maps were acquired on different\nlow-carbon steels; the prior austenitic grains were automatically reconstructed\nand the traces of the habit planes predicted by the different models were\nanalyzed and compared to the morphologies. This experimental work shows that\n{575}fcc planes are the habit plane of the blocks, and that the habit plane of\none block often dominates the others, which impedes to discriminate the\ndifferent models. The advantages of our model are its simplicity, the absence\nof fitting parameters, and the symmetric role played by the variants the\nblocks."
    },
    {
        "anchor": "Phase Separating Electrode Materials Chemical Inductors: We discover presence of chemical inductive effects in phase separating ion\nintercalation energy storage materials, specifically in lithium iron phosphate\n(LFP) and also lithium titanate oxide (LTO). These materials features fast\n(de)intercalation and slow diffusion relaxation phenomena which are\nprerequisites for observing such inductive effects. Presented finding is\nsupported by the mechanistic model and analytical reasoning indicating that all\nequilibrium states that lay inside the miscibility gap of the phase separating\nmaterial exhibit strong inductive response in the low frequency part of\nspectrum. We also explain why such inductive effects are not observed outside\nthe miscibility gap. This letter presents the first mechanistic reasoning of\npreviously reported electrode level experimental observation of inductance\nduring impedance measurements at low currents.",
        "positive": "Anomalous phonon behavior in the high temperature shape memory alloy:\n  TiPd:Cr: Ti50 Pd50-xCrx is a high temperature shape memory alloy with a martensitic\ntransformation temperature strongly dependent on the Cr composition. Prior to\nthe transformation a premartensitic phase is present with an incommensurate\nmodulated cubic lattice with wave vector of q0=(0.22, 0.22, 0). The temperature\ndependence of the diffuse scattering in the cubic phase is measured as a\nfunction temperature for x=6.5, 8.5, and 10 at. %. The lattice dynamics has\nbeen studied and reveals anomalous temperature and q-dependence of the\n[110]-TA2 transverse phonon branch. The phonon linewidth is broad over the\nentire Brillouin zone and increases with decreasing temperature, contrary to\nthe behavior expected for anharmonicity. No anomaly is observed at q0. The\nresults are compared with first principles calculation of the phonon structure."
    },
    {
        "anchor": "Effect of strain on the electrical transport and magnetization of the\n  epitaxial Pr0.5Ca0.5MnO3/La0.5Ca0.5MnO3/ Pr0.5Ca0.5MnO3 trilayer structures: Epitaxial trilayer structures consisting of two antifferomagnetic\ncharge/orbital order insulators Pr0.5Ca0.5MnO3 (PCMO) and La0.5Ca0.5MnO3 (LCMO)\nare grown on (001)-oriented SrTiO3 and LaAlO3 substrates. In this trilayer\nseries, a thin film of LCMO with various thicknesses is sandwiched between the\ntwo fixed thicknesses of PCMO. These samples show a Curie temperature with a\nhysteretic field dependent magnetization at 10 K, although the individual\ncompounds are antiferromagnetic. The zero field electronic transport of all\nsamples on LAO shows thermally activated behavior, while the thermally\nactivated behavior is suppressed and a metal-like transport is appearing for\nthe samples on STO as the LCMO layer thickness increases above 10 unit cell. We\nhave discussed these magnetic and transport properties of the trilayer\nstructures on STO and LAO by the interfacial effect due to the stabilized CO\nstate and the vibration mode of Jahn-Teller distortion.",
        "positive": "Abnormal behavior of crystalline methane in temperature interval\n  $60-70~K$. From experiment to theory: The paper presents an analysis of mechanical, structural, thermophysical and\nspectral properties of solid methane in temperature interval $0.5T_{tr}\n-T_{tr}$ ($T_{tr}$ is the triple point temperature) under equilibrium vapor\npressure. It is shown that the anomalies of the studied properties at\ntemperatures 60--70~K have been observed in the body of the reviewed papers. A\nconcept of \"topons\" (collective excitations of rotational degrees of freedom in\nsolid methane) is proposed. A whole of the observed anomalies can be explained\nin the frames of this concept.\n  Key words: solid methane, quantum crystals, rotational degrees of freedom,\nthermophysical and mechanical properties of the crystals"
    },
    {
        "anchor": "Giant texturing effect in multiferroic MnWO$_4$ polycrystals: Different methods of texturing polycrystalline materials are developed over\nyears to use/probe anisotropic material properties with relative ease, where\ncomplicated and expensive single crystal growth processes could be avoided. In\nthis paper, particle morphology assisted texturing in multiferroic MnWO$_4$ has\nbeen discussed. Detailed powder x-ray diffraction vis-a-vis scanning electron\nmicroscopic studies on differently annealed and processed samples have been\nemployed to probe the giant texturing effect in powdered MnWO$_4$. A\nquantitative measure of the texturing has been carried out by means of Rietveld\nanalysis technique. Qualitative presentation of magnetic and dielectric data on\ntextured pellet demonstrated the development of clear anisotropic physical\nproperties in polycrystalline pellets. Finally, we established that the highly\nanisotropic plate like particles are formed due to easy cleavage of the\nsignificantly large crystalline grains.",
        "positive": "Phase change memory technology: We survey the current state of phase change memory (PCM), a non-volatile\nsolid-state memory technology built around the large electrical contrast\nbetween the highly-resistive amorphous and highly-conductive crystalline states\nin so-called phase change materials. PCM technology has made rapid progress in\na short time, having passed older technologies in terms of both sophisticated\ndemonstrations of scaling to small device dimensions, as well as integrated\nlarge-array demonstrators with impressive retention, endurance, performance and\nyield characteristics.\n  We introduce the physics behind PCM technology, assess how its\ncharacteristics match up with various potential applications across the\nmemory-storage hierarchy, and discuss its strengths including scalability and\nrapid switching speed. We then address challenges for the technology, including\nthe design of PCM cells for low RESET current, the need to control\ndevice-to-device variability, and undesirable changes in the phase change\nmaterial that can be induced by the fabrication procedure. We then turn to\nissues related to operation of PCM devices, including retention,\ndevice-to-device thermal crosstalk, endurance, and bias-polarity effects.\nSeveral factors that can be expected to enhance PCM in the future are\naddressed, including Multi-Level Cell technology for PCM (which offers higher\ndensity through the use of intermediate resistance states), the role of coding,\nand possible routes to an ultra-high density PCM technology."
    },
    {
        "anchor": "Ideal Weak Topological Insulator and Protected Helical Saddle Points: The paradigm of classifying three-dimensional (3D) topological insulators\ninto strong and weak ones (STI and WTI) opens the door for the discovery of\nvarious topological phases of matter protected by different symmetries and\ndefined in different dimensions. However, in contrast to the vast realization\nof STIs, very few materials have been experimentally identified as being close\nto WTI. Even amongst those identified, none exists with topological surface\nstates (TSS) exposed in a global bulk band gap that is stable at all\ntemperatures. Here we report the design and observation of an ideal WTI in a\nquasi-one-dimensional (quasi-1D) bismuth halide, Bi$_{4}$I$_{1.2}$Br$_{2.8}$\n(BIB). Via angle-resolved photoemission spectroscopy (ARPES), we identify that\nBIB hosts TSS on the (100)$\\prime$ side surface in the form of two anisotropic\n$\\pi$-offset Dirac cones (DCs) separated in momentum while topologically dark\non the (001) top surface. The ARPES data fully determine a unique side-surface\nHamiltonian and thereby identify two pairs of non-degenerate helical saddle\npoints and a series of four Lifshitz transitions. The fact that both the\nsurface Dirac and saddle points are in the global bulk band gap of 195 meV,\ncombined with the small Dirac velocities, nontrivial spin texture, and the\nnear-gap chemical potential, qualifies BIB to be not only an ideal WTI but also\na fertile ground for topological many-body physics.",
        "positive": "Microstructural Characteristics of Reaction-Bonded B4C/SiC Composite: A detailed microstructural investigation was performed to understand\nstructural characteristics of a reaction-bonded B$_4$C/SiC ceramic composite.\nThe state-of-the-art focused ion beam & scanning electron microscopy (FIB/SEM)\nand transmission electron microscopy (TEM) revealed that the as-fabricated\nproduct consisted of core-rim structures with {\\alpha}-SiC and $B_4$C cores\nsurrounded by \\beta-SiC and $B_4$C, respectively. In addition, plate-like\n\\beta-SiC was detected within the $B_4$C rim. A phase formation mechanism was\nproposed and the analytical elucidation is anticipated to shed light on\npotential fabrication optimization and the property improvement of ceramic\ncomposites."
    },
    {
        "anchor": "Quasi-nodal lines in rhombohedral magnetic materials: A well-established result in condensed matter physics states that materials\ncrystallizing in symmetry groups containing glide reflection symmetries possess\nnodal lines on the energy bands. These nodal lines are topologically protected\nand appear on the fixed planes of the reflection in reciprocal space. In the\npresence of inversion symmetry, the energy bands are degenerate and the nodal\nlines on the fixed plane may hybridize or may cross. In the former case, the\ncrossing is avoided, thus producing lines on reciprocal space where the energy\ngap is small, and in the latter, the nodal lines will endure, thus producing\nDirac or double nodal lines. In addition, if the material crystallizes in a\nferromagnetic phase where the glide reflection symmetry is broken, the nodal\nlines hybridize, thus defining lines in reciprocal space where the energy gap\nis small. In this work we concentrate our efforts on the study of nodal lines\nthat hybridize due to magnetization; we have coined the term of quasi-nodal\nlines for those lines in reciprocal space where the energy gap is small (less\nthan what can be detected experimentally). We study magnetic trifluorides and\ntrioxides which crystallize in magnetic space groups 167.107 and 161.71 and we\nshow the existence of quasi-nodal lines on these materials. We furthermore show\nthat whenever the quasi-nodal lines are located around the Fermi level then\ninteresting charge and spin transport effects are induced and can be used to\ndetect experimentally these lines. Of particular interest are the half-metallic\nferromagnetic phases of PdF3 and LiCuF3 where the large signal of the anomalous\nHall conductance is due to the presence of the quasi-nodal lines on the Fermi\nlevel.",
        "positive": "Superconducting and Antiferromagnetic Properties of Dual-Phase V$_3$Ga: The binary compound V$_3$Ga can exhibit two near-equilibrium phases,\nconsisting of the A15 structure that is superconducting, and the Heusler D0$_3$\nstructure that is semiconducting and antiferromagnetic. Density functional\ntheory calculations show that the two phases are closely degenerate, being\nseparated by only ~10 meV/atom. Magnetization measurements on bulk-grown\nsamples show superconducting behavior below 14 K. These results indicate the\npossibility of using V$_3$Ga for quantum technology devices utilizing both\nsuperconductivity and antiferromagnetism at the same temperature."
    },
    {
        "anchor": "High tunnel magnetoresistance and magnetism in metastable bcc\n  Co$_{1-x}$Mn$_x$-based magnetic tunnel junctions: Co-rich Co$_{1-x}$Mn$_x$ alloys have hcp or fcc disordered phases and those\nferromagnetic orderings are significantly deteriorated with increasing Mn\nconcentration $x$ in bulk. On the other hand, those metastable bcc phases show\nproperties attractive to spintronics, e.g., high tunnel magnetoresistance (TMR)\nratio of more than 200% (600%) at 300 K (10 K) in magnetic tunnel junctions\n(MTJs) with the $x$ = 0.25 bcc alloy electrodes [Kunimatsu et al., Appl. Phys.\nExpress 13, 083007 (2020)]. Here, we report systematic study of structure and\nmagnetism for epitaxial thin films as well as the TMR effect in\nMgO(001)-barrier MTJs with electrodes comprising those bcc films. The single\nphase bcc Co$_{1-x}$Mn$_x$(001) films were pseudomorphically grown on Cr(001)\nfor 0.14 < $x$ < 0.50 with a sputtering technique. The magnetization was larger\nthan that of pure Co for $x$ = 0.14-0.25 and deceased with further increasing\n$x$. This behavior mainly stemmed from the composition dependence of magnetic\nmoment of Mn that exceeded 2 $\\mu _B$ at the maximum, unveiled by X-ray\nmagnetic circular dichroism. Correspondingly, within the range of 0.25 < $x$ <\n0.37, the TMR ratio decreased from 620% (229%) to 450% (194%) at 10 K (300 K)\nas $x$ increased. We discussed the relationship between the magnetism and high\nTMR ratio with different $x$ with the aid of the ab-initio band structure\ncalculations.",
        "positive": "Stern and Diffuse Layer Interactions During Ionic Strength Cycling: Second harmonic generation amplitude and phase measurements are acquired in\nreal time from fused silica:water interfaces that are subjected to ionic\nstrength transitions conducted at pH 5.8. In conjunction with atomistic\nmodeling, we identify correlations between structure in the Stern layer,\nencoded in the total second-order nonlinear susceptibility, chi(2)tot, and in\nthe diffuse layer, encoded in the product of chi(2)tot and the total\ninterfacial potential, phi(0)tot. chi(2)tot:phi(0)tot correlation plots\nindicate that the dynamics in the Stern and diffuse layers are decoupled from\none another under some conditions (large change in ionic strength), while they\nchange in lockstep under others (smaller change in ionic strength) as the ionic\nstrength in the aqueous bulk solution varies. The quantitative structural and\nelectrostatic information obtained also informs on the molecular origin of\nhysteresis in ionic strength cycling over fused silica. Atomistic simulations\nsuggest a prominent role of contact ion pairs (as opposed to solvent-separated\nion pairs) in the Stern layer. Those simulations also indicate that net water\nalignment is limited to the first 2 nm from the interface, even at 0 M ionic\nstrength, highlighting water's polarization as an important contributor to\nnonlinear optical signal generation."
    },
    {
        "anchor": "Anisotropic and incommensurate spin fluctuations in hcp iron and some\n  other nearly magnetic metals: We present an ab initio theoretical formalism for the static paramagnetic\nspin susceptibility of metals at finite temperatures. Since relativistic\neffects, e.g. spin-orbit coupling, are included, we can identify the anisotropy\nor easy axes of the spin fluctuations. Our calculations find hcp-iron to be\nunstable to in ab-plane, incommensurate anti-ferromagnetic (AFM) modes (linked\nto nested Fermi surface) below T_N =69K for the lowest pressures under which it\nis stable. T_N swiftly drops to zero as the pressure is increased. The\ncalculated susceptibility of yttrium is consistent with the helical,\nincommensurate AFM order found in many rare-earth-dilute yttrium alloys.\nLastly, in line with experimental data, we find the easy axes of the\nincommensurate AFM and ferromagnetic spin fluctuations of the normal state of\nthe triplet superconductor Sr2RuO4 to be perpendicular and parallel with the\ncrystal c-axis resepctively.",
        "positive": "Structurally Triggered Metal-Insulator Transition in Rare-Earth\n  Nickelates: Rare-earth nickelates form an intriguing series of correlated perovskite\noxides. Apart from LaNiO3, they exhibit on cooling a sharp metal-insulator\nelectronic phase transition, a concurrent structural phase transition and a\nmagnetic phase transition toward an unusual antiferromagnetic spin order.\nAppealing for various applications, full exploitation of these compounds is\nstill hampered by the lack of global understanding of the interplay between\ntheir electronic, structural and magnetic properties. Here, we show from\nfirst-principles calculations that the metal-insulator transition of nickelates\narises from the softening of an oxygen breathing distortion, structurally\ntriggered by oxygen-octahedra rotation motions. The origin of such a rare\ntriggered mechanism is traced back in their electronic and magnetic properties,\nproviding a united picture. We further develop a Landau model accounting for\nthe evolution of the metal-insulator transition in terms of the $R cations and\nrationalising how to tune this transition by acting on oxygen rotation motions."
    },
    {
        "anchor": "Electric coupling to the magnetic resonance of split ring resonators: We study both theoretically and experimentally the transmission properties of\na lattice of split ring resonators (SRRs) for different electromagnetic (EM)\nfield polarizations and propagation directions. We find unexpectedly that the\nincident electric field E couples to the magnetic resonance of the SRR when the\nEM waves propagate perpendicular to the SRR plane and the incident E is\nparallel to the gap-bearing sides of the SRR. This is manifested by a dip in\nthe transmission spectrum. A simple analytic model is introduced to explain\nthis interesting behavior.",
        "positive": "Laser-Shock Compression and Hugoniot Measurements of Liquid Hydrogen to\n  55 GPa: The principal Hugoniot for liquid hydrogen was obtained up to 55 GPa under\nlaser-driven shock loading. Pressure and density of compressed hydrogen were\ndetermined by impedance-matching to a quartz standard. The shock temperature\nwas independently measured from the brightness of the shock front. Hugoniot\ndata of hydrogen provide a good benchmark to modern theories of condensed\nmatter. The initial number density of liquid hydrogen is lower than that for\nliquid deuterium, and this results in shock compressed hydrogen having a higher\ncompression and higher temperature than deuterium at the same shock pressure."
    },
    {
        "anchor": "First principles modeling of tunnel magnetoresistance of Fe/MgO/Fe\n  trilayers: By carrying out density functional theory analysis within the Keldysh\nnon-equilibrium Green's functional formalism, we have calculated the nonlinear\nand non-equilibrium quantum transport properties of Fe/MgO/Fe trilayer\nstructures as a function of external bias voltage. For well relaxed atomic\nstructures of the trilayer, the equilibrium tunnel magnetoresistance ratio\n(TMR) is found to be very large and also fairly stable against small variations\nin the atomic structure. As a function of external bias voltage, the TMR\nreduces monotonically to zero with a voltage scale of about 1V, in agreement\nwith experimental observations. We present understanding of the nonequilibrium\ntransport properties by investigating microscopic details of the scattering\nstates and the Bloch bands of the Fe leads.",
        "positive": "Multicomponent multisublattice alloys, nonconfigurational entropy and\n  other additions to the Alloy Theoretic Automated Toolkit: A number of new functionalities have been added to the Alloy Theoretic\nAutomated Toolkit (ATAT) since it was last reviewed in this journal in 2002.\nATAT can now handle multicomponent multisublattice alloy systems,\nnonconfigurational sources of entropy (e.g. vibrational and electronic\nentropy), Special Quasirandom Structures (SQS) generation, tensorial cluster\nexpansion construction and includes interfaces for multiple atomistic or ab\ninitio codes. This paper presents an overview of these features geared towards\nthe practical use of the code. The extensions to the cluster expansion\nformalism needed to cover multicomponent multisublattice alloys are also\nformally demonstrated."
    },
    {
        "anchor": "Iron-based layered superconductor LaO$_{1-x}$F$_x$FeAs: an\n  antiferromagnetic semimetal: We have studied the newly found superconductor compound LaO$_{1-x}$F$_x$FeAs\nthrough the first-principles density functional theory calculations. We find\nthat the parent compound LaOFeAs is a quasi-2-dimensional antiferromgnetic\nsemimetal with most carriers being electrons and with a magnetic moment of\n$2.3\\mu_B$ located around each Fe atom on the Fe-Fe square lattice. Furthermore\nthis is a commensurate antiferromagnetic spin density wave due to the Fermi\nsurface nesting, which is robust against the F-doping. The observed\nsuperconduction happens on the Fe-Fe antiferromagnetic layer, suggesting a new\nsuperconductivity mechanism, mediated by the spin fluctuations. An abrupt\nchange on the Hall measurement is further predicted for the parent compound\nLaOFeAs.",
        "positive": "Thermoelectric determination of electronic entropy change in Ni-doped\n  FeRh: The net entropy change corresponding to the charge carriers in a Ni-doped\nFeRh bulk polycrystal was experimentally evaluated in a single sample using low\ntemperature heat capacity experiments with applied magnetic field, and using\nSeebeck effect and Hall coefficient measurements at high temperatures across\nthe first order transition. From the heat capacity data a value for the\nelectronic entropy change \\(\\Delta S_{el}\\approx8.9\\) J\\ kg\\(^{-1}\\)K\\(^{-1}\\)\nwas extracted, whereas a value of up to 4 J\\ kg\\(^{-1}\\)K\\(^{-1}\\) was obtained\nform the Seebeck coefficient. Additionally, the analysis of the Seebeck\ncoefficient allows tracing the evolution of the electronic entropy change with\napplied magnetic field. An increase of the electronic entropy with increasing\napplied magnetic field is evidenced, as high as 10 percent at 6 T."
    },
    {
        "anchor": "Beyond the one-dimensional configuration coordinate model of\n  photoluminescence: The one-dimensional configuration coordinate model (1D-CCM) is widely used\nfor the analysis of photoluminescence in molecules and doped solids, and relies\non a linear combination of the equilibrium nuclear configurations of ground and\nexcited states. It delivers an estimation of the energy barrier at which ground\nand excited state curves cross, semi-classically linked to non-radiative\ntransition rate and thermal quenching. To assess its predictive power for the\nlatter properties, we propose a new \\textit{optimized configuration path (OCP)\nmethod in which} the ground-state and excited-state forces are mixed instead of\ntheir configurations. We also define another one-parameter model thanks a\ndouble energy parabola hypothesis (DEPH). We compare the OCP method and the\nDEPH reference with the 1D-CCM for three paradigmatic 4f-5d phosphors\nY$_3$Al$_5$O$_{12}$:Ce, Lu$_2$SiO$_5$:Ce, and YAlO$_3$:Ce. We find that the OCP\nand DEPH methods yield similar results with geometries that have significantly\nlower ground-state energies than the 1D-CCM for the same 4f-5d energy\ndifference. However, the OCP method suffers from the appearance of multiple\nlocal minima, rendering the clear determination of the optimal geometry very\ndifficult in practice. Still the OCP method allows one to quantify the\ndeviations from the 1D-CCM, therefore increasing confidence in the lower bound\nobtained from the DEPH for the 4f-5d crossing barrier, and its comparison with\nthe energy of the auto-ionization thermal quenching mechanism. We expect the\nOCP approach to be applicable to other luminescent materials or molecules.",
        "positive": "Negative spin polarization of Mn2VGa probed by tunnel magnetoresistance: The ferrimagnetic Heusler compound Mn2VGa is predicted to have a pseudogap in\nthe majority spin channel, which should lead to a negative tunnel\nmagnetoresistance. We synthesized epitaxial Mn2VGa thin films on MgO(001)\nsubstrates by dc and rf magnetron co-sputtering, resulting in nearly\nstoichiometric films. XRD analysis revealed a mostly B2-ordered structure for\nthe films deposited at substrate temperatures of 350{\\deg}C, 450{\\deg}C, and\n550{\\deg}C. Magnetic tunnel junctions with MgO barrier and CoFe\ncounter-electrodes were fabricated. After post-annealing at up to\nT_a=425{\\deg}C negative TMR was obtained around zero bias, providing evidence\nfor the inverted spin-polarization. Band structures of both electrodes were\ncomputed within the coherent potential approximation and used to calculate the\nTMR(V) characteristics, which are in good agreement with our experimental\nfindings."
    },
    {
        "anchor": "Slow sound propagation in lossy locally resonant periodic structures: We investigate the sound propagation in an air-filled tube periodically\nloaded with Helmholtz resonators. By tuning the Helmholtz with the Bragg\nresonance, we study the efficiency of slow sound propagation in the presence of\nthe intrinsic viscothermal losses of the system. While in the lossless case the\noverlapping of the resonances results in slow sound induced transparency of a\nnarrow frequency band surrounded by a strong and broadband gap, the inclusion\nof the unavoidable losses imposes limits to the slowdown factor and the maximum\ntransmission. Experiments, theory and finite element simulations have been used\nfor the characterization of acoustic wave propagation. Experiments, in good\nagreement with the lossy theory, reveal the possibility of slowing sound at low\nfrequencies by 20 times. A trade-off among the relevant parameters (delay time,\nmaximum transmission, bandwidth) as a function of the tuning between Bragg and\nHelmholtz resonance frequency is also presented.",
        "positive": "Synthesis of Different Zinc and Zinc Included Nanostructures by High\n  Power Copper Vapor Laser Ablation in Water- Surfactants Solutions: The data of experimental studies of optical characteristics of colloidal\nsolutions, composition and morphology of its dispersed phase, resulting from\nlaser ablation of zinc in aqueous solutions of anionic surfactants --- sodium\ndodecyl sulfate (SDS), dioctyl sodium sulfosuccinate (AOT) are presented. It is\nshown that by studying the optical absorption spectra of the colloid, X-ray\nspectra and AFM-images of extracted from colloid solid phase, it is possible to\ntrace the dynamics of ZnO nanostructures formation from zinc nanoclasters size\nof several nanometers to ZnO fractal aggregates (FA) size up to hundreds of\nnanometers. Determinants of this process are the average power and an ablation\nexposure, the frequency of the laser pulses, the colloid aging time, the type\nand concentration of surfactant in solution. In the selection of appropriate\nregimes, along with zinc oxide obtained other nanoproducts --- hydrozincit and\norgano-inorganic layered composite \\ce{[(\\beta) - Zn(OH)2 + SDS]}."
    },
    {
        "anchor": "Elastic aging from coexistence and transformations of ferroelectric and\n  antiferroelectric states in PZT: Materials undergoing antiferroelectric/ferroelectric (AFE/FE) transitions are\nstudied for possible applications that exploit the large volume, charge and\nentropy differences between the two states, such as electrocaloric cooling,\nenergy storage, electromechanical actuators. Though certain compositions of PZT\ncodoped with La and Sn may withstand millions of electrically induced AFE/FE\ncycles, in other cases few thermally induced cycles and room temperature aging\nmay cause noticeable changes in the material properties. This is particularly\nevident in the elastic moduli, which at room temperature can become as much as\nfour times softer. In order to get more insight into the mechanisms involved in\nsuch elastic aging and full recovering with mild annealing at 600-800 K, the\neffect of La doping on PZT with 4.6% Ti is studied with anelastic measurements.\nComplete suppression of the time dependent phenomena is found after the\ntransformation of the intermediate FE phase into incommensurate AFE by 2% La\ndoping. This is discussed in terms of disappearance of the stress and electric\nfields at the FE/AFE interfaces, in the light of the thermally activated\nanelastic relaxation processes that are observed at high temperature, and are\ndue to mobile defects, presumably O vacancies.",
        "positive": "Finite Size Effects in Highly Scaled Ruthenium Interconnects: Ru has been considered a candidate to replace Cu-based interconnects in VLSI\ncircuits. Here, a methodology is proposed to predict the resistivity of (Ru)\ninterconnects. First, the dependence of the Ru thin film resistivity on the\nfilm thickness is modeled by the semiclassical Mayadas-Shatzkes (MS) approach.\nThe fitting parameters thus obtained are then used as input in a modified MS\nmodel for nanowires to calculate wire resistivities. Predicted experimental\nresistivities agreed within about 10%. The results further indicate that grain\nboundary scattering was the dominant scattering mechanism in scaled Ru\ninterconnects."
    },
    {
        "anchor": "Surpassing the Ambient Packing Limit of Energetic Crystals: Squeezing\n  Effect of Molecular Level \"Net-fishing\": High energy density is always a key goal for developments of energy storage\nor energetic materials (EMs). Except exploring novel EMs with high chemical\nenergy, it is also desirable if the traditional EMs could be assembled at a\nhigher density. However, it is very difficult to surpass their theoretical\nmaximum molecular packing density under ambient conditions, even though a\nhigher density could be achieved under ultra-high pressure (Gigapascals). Such\nsolid-state phase changes are reversible, and hence this high density packing\nis not able to maintain under ambient conditions. Alternatively, in this\nresearch, we demonstrated a molecular level compression effect by stacking of\n2-D TAGP, resulting in a higher density packing of the HMX molecules with\nchanged conformation. The HMX crystal formed under compression in the solvent\nhas a unit cell parameter very close to the reported one observed under\npressure of 0.2 GPa. It shows that the compressed HMX molecules are trapped in\nthe TAGP layers, resulting in a higher density (e.g. 2.13 g cm-3) and also\nhigher heat of formation. The resulted HMX crystals are free of defects, and\nunlike the pristine HMX, no polymorphic transition and melting point were\nobserved upon heating. Experiments and relevant calculations show that the best\nresulted hybrid HMX crystal has a detonation velocity of 10.40 km s-1 and\npressure of 53.9 GPa, respectively. Its ground specific impulse reaches about\n292 s, even much better than CL-20, making it a promising propellant component\nfor future space explorations.",
        "positive": "Current-driven microwave oscillations in current perpendicular-to-plane\n  spin-valve nanopillars: We study the current and temperature dependences of the microwave voltage\nemission of spin-valve nanopillars subjected to an in-plane magnetic field and\na perpendicular-to-plane current. Despite the complex multilayer geometry,\nclear microwave emission is shown to be possible and spectral lines as narrow\nas 3.8 MHz (at 150 K) are observed."
    },
    {
        "anchor": "Hysteresis in Two Dimensional Arrays of Magnetic Nanoparticles: We perform computer simulations to probe the magnetic hysteresis in a\ntwo-dimensional ($L^{}_x\\times L^{}_y$) assembly of magnetic nanoparticles as a\nfunction of dipolar interaction strength $h^{}_d$, temperature $T$, aspect\nratio $A^{}_r=L^{}_y/L^{}_x$, and the applied alternating magnetic field's\ndirection. In the absence of magnetic interaction ($h^{}_d\\approx0$) and\nthermal fluctuations ($T=0$ K), the hysteresis follows the Stoner and Wohlfarth\nmodel, as expected. For weak dipolar interaction and substantial temperature,\nthe hysteresis has the dominance of superparamagnetic behaviour, irrespective\nof the applied magnetic field's direction and $A^{}_r$. Interestingly, the\nhysteresis curve has all the characteristics of antiferromagnetic interaction\ndominance for $A^{}_r\\leq6$ and considerable dipolar interaction strength\n($h^{}_d>0.2)$, which is independent of applied magnetic direction. When the\nmagnetic field is applied along the system's shorter axis ($x$-direction), a\nnon-hysteresis straight line is observed with large $h^{}_d$. In the case of\nthe magnetic field applied along the long axis of the sample ($y$-direction),\nferromagnetic interaction dominates the hysteresis for large $h^{}_d$ and\n$A^{}_r>6$. Irrespective of $h^{}_d$ and applied magnetic field's direction,\nthe coercive field $\\mu^{}_oH^{}_c$ and remanence $M^{}_r$ are minimal for\n$A^{}_r\\leq6$ and significant temperature. They are found to increase with\n$h^{}_d$ when $A^{}_r$ is enormous. Remarkably, the variation of hysteresis\nloop area $E^{}_H$ as a function of these parameters is the same as that of the\ncoercive field variation. We believe that the concepts presented in this work\nare relevant in various technological applications such as spintronics and\nmagnetic hyperthermia, in which such self-assembled nanoparticle arrays are\nubiquitous.",
        "positive": "Modeling huge photoinduced spin polarons in intrinsic magnetic\n  semiconductors: In intrinsic magnetic semiconductors, the absorption of a single photon can\ngenerate a spin polaron, whose magnetic moment reaches many thousands of Bohr\nmagnetons [1.2]. Here we investigate photoinduced spin polarons, using Monte\nCarlo simulations. In antiferromagnetic semiconductors, photoinduced spin\npolarons are most efficiently generated in the whole temperature interval up to\nthe phase transition, whereas in ferromagnetic semiconductors much larger spin\npolarons can be photoinduced, but only around the phase transition temperature.\nBecause Monte Carlo simulations are computationally expensive, we developed an\nanalytical model, based on the Weiss field theory. Although the Weiss model\ndoes not provide as much information as a Monte Carlo simulation, such as spin\ntexture and fluctuations, it yields formulas that can be used to estimate\ninstantly the expected photoinduced spin polaron size in many intrinsic\nmagnetic semiconductors."
    },
    {
        "anchor": "Bethe-Salpeter equation for absorption and scattering spectroscopy:\n  Implementation in the $\\texttt{exciting}$ code: The Bethe-Salpeter equation for the electron-hole correlation function is the\nstate-of-the-art formalism for optical and core spectroscopy in condensed\nmatter. Solutions of this equation yield the full dielectric response,\nincluding both the absorption and the inelastic scattering spectra. Here, we\npresent an efficient implementation within the all-electron full-potential code\n$\\texttt{exciting}$, which employs the linearized augmented plane-wave\n(L)APW+LO basis set. Being an all-electron code, $\\texttt{exciting}$ allows the\ncalculation of optical and core excitations on the same footing. The\nimplementation fully includes the effects of finite momentum transfer which may\noccur in inelastic x-ray spectroscopy and electron energy-loss spectroscopy.\nOur implementation does not require the application of the Tamm-Dancoff\napproximation that is commonly employed in the determination of absorption\nspectra in condensed matter. The interface with parallel linear-algebra\nlibraries enables the calculation for complex systems. The capability of our\nimplementation to compute, analyze, and interpret the results of different\nspectroscopic techniques is demonstrated by selected examples of prototypical\ninorganic and organic semiconductors and insulators.",
        "positive": "Electrophoretic deposition of WS2 flakes on nanoholes arrays. Role of\n  the used suspension medium: Here we optimized the electrophoretic deposition process for the fabrication\nof WS2 plasmonic nanohole integrated structures. We showed how the conditions\nused for the site selective deposition influenced the properties of the\ndeposited flakes. In particular, we investigated the effect of different\nsuspension medium used during the deposition both in the efficiency of the\nprocess and in the stability of WS2 flakes, which were deposited on a ordered\narrays of plasmonic nanostructures."
    },
    {
        "anchor": "Evolving properties of two dimensional materials, from graphene to\n  graphite: We have studied theoretically, using density functional theory, several\nmaterials properties when going from one C layer in graphene to two and three g\nraphene layers and on to graphite. The properties we have focused on are the\nelastic constants, electronic structure (energy bands and density of state s),\nand the dielectric properties. For any of the properties we have investigated\nthe modification due to an increase in the number of graphene layers is within\na few percent. Our results are in agreement with the analysis presented\nrecently by Kopelevich and Esquinazi (unpublished).",
        "positive": "Effects of a non-causal electromagnetic response on the linear momentum\n  transfer from a swift electron to a metallic nanoparticle: Electron beams in Scanning Transmission Electron Microscopes (STEMs) can be\nused as a tool to induce movement on nanoparticles. Employing a\nclassical-electrodynamics approach, it has been reported that the linear\nmomentum transfer from a STEM-beam electron to a metallic spherical\nnanoparticle can be either repulsive or attractive towards the swift electron\ntrajectory. This is in qualitative agreement with experimental observations.\nThe interaction time between a swift electron and a nanoparticle is typically\non the order of attoseconds. Hence, the electromagnetic response of the\nnanoparticle at short times is of utmost importance. However, it has been\nreported that the dielectric function employed in previous studies presented a\nnon-causal pre-echo at the attosecond timescale, which might have lead to\nincorrect unphysical results. Therefore, the validity of these linear momentum\ntransfer results should be revisited. In this theoretical work, we study the\nnon-causality effects on the linear momentum transferred from a swift electron\nto a metallic nanoparticle, made of either aluminum or gold. Using an efficient\nnumerical methodology, we found that non-causality, as well as deficient\nnumerical convergence, may lead to incorrect repulsive linear momentum transfer\nresults. Contrary to what previous theoretical studies have reported, our\nresults show that the linear momentum transfer from a swift electron to\nspherical aluminum and gold nanoparticles, with radius 1 nm, is always\nattractive."
    },
    {
        "anchor": "Intrinsic limits governing MBE growth of Ga-assisted GaAs nanowires on\n  Si(111): Diffusion-enhanced and desorption-limited growth regimes of Ga-assisted GaAs\nnanowires were identified. In the latter regime, the number of vertical NWs\nwith a narrow length distribution was increased by raising the growth\ntemperature. The maximum axial growth rate; which can be quantified by the\nsupplied rate of As atoms, is achieved when a dynamical equilibrium state is\nmaintained in Ga droplets i.e. the number of impinging As atoms on the droplet\nsurface is equivalent to that of direct deposited Ga atoms combining with the\ndiffusing ones. The contribution of Ga diffusion to the wire growth was\nevidenced by the diameter-dependent NW axial growth rate.",
        "positive": "Magnetism in Re-based ferrimagnetic double perovskites: We have investigated spin and orbital magnetic moments of the Re 5d ion in\nthe double perovskites A2FeReO6 (A = Ba, Sr, Ca) by X-ray magnetic circular\ndichroism (XMCD) at the Re L(2,3) edges. In these ferrimagnetic compounds an\nunusually large negative spin and positive orbital magnetic moment at the Re\natoms was detected. The presence of a finite spin magnetic moment in a\n'non-magnetic' double perovskite as observed in the double perovskite Sr2ScReO6\nproves that Re has also a small, but finite intrinsic magnetic moment. We\nfurther show for the examples of Ba and Ca that the usually neglected alkaline\nearth ions undoubtedly also contribute to the magnetism in the ferrimagnetic\ndouble perovskites."
    },
    {
        "anchor": "First-principles calculations of phonon and thermodynamic properties of\n  AlRE (RE= Y, Gd, Pr, Yb) intermetallic compounds: The phonon and thermodynamic properties of rare-earth-aluminum intermetallics\nAlRE (RE=Y, Gd, Pr, Yb) with B2-type structure are investigated by performing\ndensity functional theory and density functional perturbation theory within the\nquasiharmonic approximation. The phonon spectra and phonon density of states,\nincluding the phonon partial density of states and total density of states,\nhave been discussed. Our results demonstrate that the density of states is\nmostly composed of Al states at the high frequency. The temperature dependence\nof various quantities such as the thermal expansions, the heat capacities at\nconstant volume and constant pressure, the isothermal bulk modulus, and the\nentropy are obtained. The electronic contribution to the specific heat is\ndiscussed, and the presented results show that the thermal electronic\nexcitation affecting the thermal properties is inessential.",
        "positive": "Characterization of Traps at Nitrided SiO$_2$/SiC Interfaces near the\n  Conduction Band Edge by using Hall Effect Measurements: The effects of nitridation on the density of traps at SiO$_2$/SiC interfaces\nnear the conduction band edge were qualitatively examined by a simple, newly\ndeveloped characterization method that utilizes Hall effect measurements and\nsplit capacitance-voltage measurements. The results showed a significant\nreduction in the density of interface traps near the conduction band edge by\nnitridation, as well as the high density of interface traps that was not\neliminated by nitridation."
    },
    {
        "anchor": "Nanostructuring of Ba8Ga16Ge30 clathrates: First thermoelectric properties measurements on bulk nanostructured\nBa8Ga16Ge30 clathrate-I are presented. A sol-gel-calcination route was\ndeveloped for preparing amorphous nanosized precursor oxides. The further\nreduction of the oxides led to quantitative yield of crystalline nanosized\nBa8Ga16Ge30 clathrate-I. TEM investigations show the clathrate nanoparticles\nretain the size and morphology of the precursor oxides. The clathrate\nnanoparticles contain mainly thin plates (approx. 300 nm x 300 nm x 50 nm) and\na small amount of nanospheres (diameter ~ 10 nm). SAED patterns confirm the\nclathrate-I structure type for both morphologies. The powders were compacted\nvia Spark Plasma Sintering (SPS) to obtain a bulk nano-structured material. The\nSeebeck coefficient S, measured on low-density samples (53% of {\\delta}x-ray),\nreaches -145 {\\mu}V/k at 375 {\\deg}C. The ZT values are quite low (0.02) due to\nthe high resistivity of the sample (two orders of magnitude larger than bulk\nmaterials) and the low sample density. The trend of the temperature dependence\nof S is in agreement with the values obtained from electronic structure\ncalculations and semi-classical Boltzmann transport theory within the constant\nscattering approximation. The total thermal conductivity (1.61 W/mK), measured\non high density samples (93% of {\\delta}x-ray), shows a reduction of 20-25% in\nrelation to the bulk materials (2.1 W/mK). A further shaping of the sample for\nthe Seebeck coefficient and electrical conductivity measurements was not\npossible due to the presence of cracks. An improvement on the design of the\npressing tools, loading of the sample and profile of the applied pressure will\nenhance the mechanical stability of the samples. These investigations are now\nin progress.",
        "positive": "A Novel Magnetic Material by Design: Observation of Yb3+ with Spin-1/2\n  and Possible Superconducting Trace in YbxPt5P: The localized f-electrons enrich the magnetic properties in rare-earth-based\nintermetallics. Among those, compounds with heavier 4d and 5d transition metals\nare even more fascinating because anomalous electronic properties may be\ninduced by the hybridization of 4f and itinerant conduction electrons primarily\nfrom the d orbitals. Here, we describe the observation of trivalent Yb3+ with S\n= 1/2 at low temperatures in YbxPt5P, the first of a new family of materials.\nYbxPt5P (0.20< x <1) phases were synthesized and structurally characterized.\nThey exhibit a large homogeneity width with the Yb ratio exclusively occupying\nthe 1a site in the anti-CeCoIn5 structure. Moreover, the resistivity\nmeasurement of a sample analyzed as Yb0.25Pt5P shows it to exist a complete\nzero-resistance transition with a critical transition temperature of ~0.6 K,\npossible superconductivity. However, the zero-resistivity transition was not\nobserved in YbPt5P with antiferromagnetic ordering existing solely.\nFirst-principles electronic structure calculations substantiate the\nantiferromagnetic ground state and indicate that 2D nesting around the Fermi\nlevel may give rise to exotic physical properties, such as superconductivity.\nYbxPt5P appears to be a unique case among materials."
    },
    {
        "anchor": "Flexomagnetoelectric Interaction in Cubic, Tetragonal and Orthorhombic\n  Crystals: The phenomenological theory of the flexomagnetoelectric coupling in crystals\nof the cubic, tetragonal and orthorhombic crystal systems has been suggested.\nSecondary role of the crystal structure chirality was shown. Oppositely,\nsignificant role of the crystallographic point group type (symmetric,\nalternating, dihedral or cyclic) in the flexomagnetoelectric coupling has been\nderived. It was shown, that conceptually new features of the\nflexomagnetoelectric effects are expected in the crystals of the cyclic groups\n(crystal classes 4/m, 4^- and 4). Proposed verification of the theory is\ninvestigation of the domain wall bend details (changes of the effect symmetry).\nSpecial case of such verification near the compensation point is suggested.\nFirst-principles mechanisms of the flexomagnetoelectric interaction were\ndiscussed.",
        "positive": "Floquet Topological Insulator in Semiconductor Quantum Wells: Topological phase transitions between a conventional insulator and a state of\nmatter with topological properties have been proposed and observed in mercury\ntelluride - cadmium telluride quantum wells. We show that a topological state\ncan be induced in such a device, initially in the trivial phase, by irradiation\nwith microwave frequencies, without closing the gap and crossing the phase\ntransition. We show that the quasi-energy spectrum exhibits a single pair of\nhelical edge states. The velocity of the edge states can be tuned by adjusting\nthe intensity of the microwave radiation. We discuss the necessary experimental\nparameters for our proposal. This proposal provides an example and a proof of\nprinciple of a new non-equilibrium topological state, Floquet topological\ninsulator, introduced in this paper."
    },
    {
        "anchor": "Structural Phase Transformations in Iron-Chalcogen under High Pressures: We report high pressure structural phase transformation sequence in a layered\nIron-based superconducting compound FeSe0.3Te0.7 to 31 GPa at room temperature.\nThe ambient pressure PbO type tetragonal phase (Space Group - P4/nmm)\ntransforms to a monoclinic phase (Space group - P21/m) at a pressure of 7.3 \\pm\n0.9 GPa. This monoclinic phase is similar to the one observed below 100 K at\nambient pressure. On further increase of pressure above 12 GPa, a\ntransformation to an amorphous phase is observed that is completed by 20 GPa.\nThe amorphous phase is found to be stable to the highest pressure of 31 GPa.\nThis structural sequence of tetragonal \\to monoclinic \\to amorphous phase\ntransformation appears to be a common feature of iron-based layered\nsuperconductors under compression. The pressure induced structural phase\ntransformations are likely to play a key role in the superconductivity in these\nmaterials at high pressures.",
        "positive": "Czochralski growth of tin crystals as a multi-physical model experiment: A new setup for Czochralski growth of model materials in air atmosphere has\nbeen developed. It includes various in-situ measurements to access the basic\nphysical phenomena on a macroscopic level: heat transfer, electromagnetism,\nmelt and gas flows, crystal stresses. A reference experiment with tin is\nperformed and analyzed using simple analytical estimates as well as 2D\nnumerical simulations with open source models. This study aims to improve the\nbasic physical understanding of the Czochralski growth process and to provide a\nuseful tool for education and research, both for non-specialists and\nscientists."
    },
    {
        "anchor": "Terahertz Kerr effect in a methylammonium lead bromide perovskite\n  crystal: We have observed short-lived optical birefringence in a CH$_3$NH$_3$PbBr$_3$\nsingle crystal induced by a powerful nearly single-cycle terahertz pulse. Apart\nfrom the instantaneous contribution that follows the profile of the squared\npump electric field, the recorded anisotropy signal contains an exponential\ncomponent decaying in $\\sim$ 350 fs, underdamped oscillations at the frequency\nof $\\sim$ 0.16 THz and an intermediate picosecond relaxation process with a\nGaussian tail. We associate these three non-trivial features with,\nrespectively, Kerr effect in the inorganic lattice, terahertz-induced transient\nalignment of CH$_3$NH$_3^+$ cations, and their coherent rotation excited by the\nterahertz pulse in a Raman process.",
        "positive": "One-magnon (electromagnon) light scattering in BiFeO3 single crystals: We observed Raman scattering from magnon in frequency range from 10 to 65\ncm-1 in BiFeO3 single crystals at cryogenic temperatures; the temperature\ndependence of the magnon frequency at 18.2 cm-1 approximates an S=5/2 Brillouin\nfunction up to the temperature (280 K) at which the magnon becomes overdamped.\nThe diverging cross-section and the frequency-shift at 140K and 200 K implies a\nmagnon-reorientation transition as in orthoferrites. Magnons in polar materials\nsuch as BiFeO3 are often termed electromagnons meaning that they possess an\nelectric dipole moment due to magnetoelectric coupling."
    },
    {
        "anchor": "Optical properties of bulk semiconductors and graphene/boron-nitride:\n  The Bethe-Salpeter equation with derivative discontinuity-corrected DFT\n  energies: We present an efficient implementation of the Bethe-Salpeter equation (BSE)\nfor optical properties of materials in the projector augmented wave method\nGPAW. Single-particle energies and wave functions are obtained from the GLLBSC\nfunctional which explicitly includes the derivative discontinuity, is\ncomputationally inexpensive, and yields excellent fundamental gaps.\nElectron-hole interactions are included through the BSE using the statically\nscreened interaction evaluated in the random phase approximation. For a\nrepresentative set of semiconductors and insulators we find excellent agreement\nwith experiments for the dielectric functions, onset of absorption, and lowest\nexcitonic features. For the two-dimensional systems of graphene and hexagonal\nboron-nitride (h-BN) we find good agreement with previous many-body\ncalculations. For the graphene/h-BN interface, we find that the fundamental and\noptical gaps of the h-BN layer are reduced by 2.0 eV and 0.7 eV, respectively,\ncompared to freestanding h-BN. This reduction is due to image charge screening\nwhich shows up in the GLLBSC calculation as a reduction (vanishing) of the\nderivative discontinuity.",
        "positive": "Oxygen reduction mechanisms in nanostructured La0.8Sr0.2MnO3 cathodes\n  for Solid Oxide Fuel Cells: In this work we outline the mechanisms contributing to the oxygen reduction\nreaction in nanostructured cathodes of La0.8Sr0.2MnO3 (LSM) for Solid Oxide\nFuel Cells (SOFC). These cathodes, developed from LSM nanostructured tubes, can\nbe used at lower temperatures compared to microstructured ones, and this is a\ncrucial fact to avoid the degradation of the fuel cell components. This\nreduction of the operating temperatures stems mainly from two factors: i) the\nappearance of significant oxide ion diffusion through the cathode material in\nwhich the nanostructure plays a key role and ii) an optimized gas phase\ndiffusion of oxygen through the porous structure of the cathode, which becomes\nnegligible. A detailed analysis of our Electrochemical Impedance Spectroscopy\nsupported by first principles calculations point towards an improved overall\ncathodic performance driven by a fast transport of oxide ions through the\ncathode surface."
    },
    {
        "anchor": "Two-Dimensional Si-Ge Monolayers: Stabilities, Structures and Electronic\n  Properties: Si-Ge monolayers (SiGeM) with different elementary proportion x (0<x<1) were\nsystematically studied for the first-time using ab initio calculations in this\nwork. The structural stabilities of the Si1-xGexM with different symmetries\nwere investigated using phonon spectra, and an infinite miscibility between Si\nand Ge elements were revealed in the 2D honeycomb structures. The simulated\nscanning tunneling microscope images and Raman and infrared active modes of the\nSi1-xGexM were then obtained for structural characterizations. Interestingly,\nthe study of electronic properties revealed not previously reported oscillatory\nnonlinear dependence of band gap values on the elementary proportion x in the\nSi1-xGexM, which suggests an alternative way for tuning the band gaps of 2D\nmaterials. Additionally, low effective masses (0.008m0 ~ 0.021m0) of the\ncarriers in the semiconducting Si1-xGexM were found, which has potentials for\nhigh-speed applications. Considering the advantage of their compatibility with\ncurrent Si-based technology and the trend of miniature of electronic devices,\nthe Si1-xGexM with stable structures and excellent properties would be\nimportant for 2D applications based on group IV materials.",
        "positive": "Chaotic spin precession in antiferromagnetic domain walls: In contrast with rich investigations about the translation of an\nantiferromagnetic (AFM) texture, spin precession in an AFM texture is seldom\nconcerned for lacking an effective driving method. In this work, however, we\nshow that under an alternating spin-polarized current with spin along the AFM\nanisotropy axis, spin precession can be excited in an AFM DW. Especially,\nchaotic spin precession occurs at moderate interfacial Dzyaloshinskii-Moriya\ninteraction (DMI), which contributes to a nonlinear term in the dynamic\nequation of DW precession. Also, crisis-induced intermittent chaos appears when\nthe current density is higher than a critical value. This work not only paves a\nway to unravel rich spin precession behaviors in an AFM texture but also\nprovides guidelines for developing ultrafast spintronic devices based on new\nphysical principles."
    },
    {
        "anchor": "Topological mechanochemistry of graphene: In view of a formal topology, two common terms, namely, connectivity and\nadjacency, determine the quality of C-C bonds of sp2 nanocarbons. The feature\nis the most sensitive point of the inherent topology of the species so that\nsuch external action as mechanical deformation should obviously change it and\nresult in particular topological effects. The current paper describes the\neffects caused by uniaxial tension of a graphene molecule in due course of a\nmechanochemical reaction. Basing on the molecular theory of graphene, the\neffects are attributed to both mechanical loading and chemical modification of\nedge atoms of the molecule. The mechanical behavior is shown to be not only\nhighly anisotropic with respect to the direction of the load application, but\ngreatly dependent on the chemical modification of the molecule edge atoms thus\nrevealing topological character of the graphene deformation.",
        "positive": "Aging-induced complex transformation behavior of martensite in\n  Ni57.5Mn17.5Ga25 shape memory alloy: Ni57.5Mn17.5Ga25 shape memory alloy exhibits a complex transformation\nbehavior, appearing after aging. Aging in the austenitic state resulted in an\nordinary decrease of the martensitic transformation temperature. Contrary to\nthis, aging in the martensitic state brought about unusual features of the\nmartensitic transformation observed so far only in Ni-Ti alloys."
    },
    {
        "anchor": "Performant implementation of the atomic cluster expansion (PACE):\n  Application to copper and silicon: The atomic cluster expansion is a general polynomial expansion of the atomic\nenergy in multi-atom basis functions. Here we implement the atomic cluster\nexpansion in the performant C++ code \\verb+PACE+ that is suitable for use in\nlarge scale atomistic simulations. We briefly review the atomic cluster\nexpansion and give detailed expressions for energies and forces as well as\nefficient algorithms for their evaluation. We demonstrate that the atomic\ncluster expansion as implemented in \\verb+PACE+ shifts a previously established\nPareto front for machine learning interatomic potentials towards faster and\nmore accurate calculations. Moreover, general purpose parameterizations are\npresented for copper and silicon and evaluated in detail. We show that the new\nCu and Si potentials significantly improve on the best available potentials for\nhighly accurate large-scale atomistic simulations.",
        "positive": "A First-Principles Study on the Adsorption of Small Molecules on\n  Arsenene: Comparison of Oxidation Kinetics in Arsenene, Antimonene,\n  Phosphorene and InSe: Arsenene, a new group V two-dimensional (2D) semiconducting material beyond\nphosphorene and antimonene, has recently gained an increasing attention owning\nto its various interesting properties which can be altered or intentionally\nfunctionalized by chemical reactions with various molecules. This work provides\na systematic study on the interactions of arsenene with the small molecules,\nincluding H2, NH3, O2, H2O, NO, and NO2. It is predicted that O2, H2O, NO, and\nNO2 are strong acceptors, while NH3 serves as a donor. Importantly, it is shown\na negligible charge transfer between H2 and arsenene which is ten times lower\nthan that between H2 and phosphorene and about thousand times lower than that\nbetween H2 and InSe and antimonene. The calculated energy barrier for O2\nsplitting on arsenene is found to be as low as 0.67 eV. Thus, pristine arsenene\nmay easily oxidize in ambient conditions as other group V 2D materials. On the\nother hand, the acceptor role of H2O on arsenene, similarly to the cases of\nantimonene and InSe, may help to prevent the proton transfer between H2O and O\nspecies by forming acids, which suppresses further structural degradation of\narsenene. The structural decomposition of the 2D layers upon interaction with\nthe environment may be avoided due to the acceptor role of H2O molecules as the\nstudy predicts from the comparison of common group V 2D materials. However, the\nprotection for arsenene is still required due to its strong interaction with\nother small environmental molecules. The present work renders the possible ways\nto protect arsenene from structure degradation and to modulate its electronic\nproperties, which is useful for the material synthesis, storage and\napplications."
    },
    {
        "anchor": "Probing the Nanoskyrmion Lattice on Fe/Ir(111) with Magnetic Exchange\n  Force Microscopy: We demonstrate that the magnetic nanoskyrmion lattice on the Fe monolayer on\nIr(111) and the positions of the Fe atoms can be resolved simultaneously using\nmagnetic exchange force microscopy. Thus, the relation between magnetic and\natomic structure can be determined straightforwardly by evaluating the Fourier\ntransformation of the real space image data. We further show that the magnetic\ncontrast can be mapped on a Heisenberg-like magnetic interaction between tip\nand sample spins. Since our imaging technique is based on measuring forces, our\nobservation paves the way to study skyrmions or other complex spin textures on\ninsulating sample systems with atomic resolution.",
        "positive": "The Development of Epitaxial Graphene For 21st Century Electronics: Graphene has been known for a long time but only recently has its potential\nfor electronics been recognized. Its history is recalled starting from early\ngraphene studies. A critical insight in June, 2001 brought to light that\ngraphene could be used for electronics. This was followed by a series of\nproposals and measurements. The Georgia Institute of Technology (GIT) graphene\nelectronics research project was first funded, by Intel in 2003, and later by\nthe NSF in 2004 and the Keck foundation in 2008. The GIT group selected\nepitaxial graphene as the most viable route for graphene based electronics and\ntheir seminal paper on transport and structural measurements of epitaxial\ngraphene was published in 2004. Subsequently, the field rapidly developed and\nmultilayer graphene was discovered at GIT. This material consists of many\ngraphene layers but it is not graphite: each layer has the electronic structure\nof graphene. Currently the field has developed to the point where epitaxial\ngraphene based electronics may be realized in the not too distant future."
    },
    {
        "anchor": "Enhancement of the lifetime of metastable states in Er-doped Si\n  nanocrystals by external coloured noise: The changes in the lifetime of a metastable energy level in Er-doped Si\nnanocrystals in the presence of an external source of colored noise are\nanalyzed for different values of noise intensity and correlation time. Exciton\ndynamics is simulated by a set of phenomenological rate equations which take\ninto account all the possible phenomena inherent to the energy states of Si\nnanocrystals and Er$^{3+}$ ions in the host material of Si oxide. The\nelectronic deexcitation is studied by examining the decay of the initial\npopulation of the Er atoms in the first excitation level $^4$I$_{13/2}$ through\nthe fluorescence and the cooperative upconversion by energy transfer. Our\nresults show that the deexcitation process of the level $^4$I$_{13/2}$ is\nslowed down within wide ranges of noise intensity and correlation time.\nMoreover, a nonmonotonic behavior of the lifetime with the amplitude of the\nfluctuations is found, characterized by a maximum variation for values of the\nnoise correlation time comparable to the deexcitation time. The indirect\ninfluence of the colored noise on the efficiency of the energy transfer\nupconversion activated from the level $^4$I$_{13/2}$ is also discussed.",
        "positive": "Ab initio study of the double row model of the Si(553)-Au reconstruction: Using x-ray diffraction Ghose et al. [Surf. Sci. {\\bf 581} (2005) 199] have\nrecently produced a structural model for the quantum-wire surface Si(553)-Au.\nThis model presents two parallel gold wires located at the step edge. Thus, the\nstructure and the gold coverage are quite different from previous proposals. We\npresent here an ab initio study using density functional theory of the\nstability, electronic band structure and scanning tunneling microscopy images\nof this model."
    },
    {
        "anchor": "Anomalous Second Harmonic Generation from Atomically Thin MnBi2Te4: MnBi2Te4 is a van der Waals topological insulator with intrinsic intralayer\nferromagnetic exchange and A-type antiferromagnetic interlayer coupling.\nTheoretically, it belongs to a class of structurally centrosymmetric crystals\nwhose layered antiferromagnetic order breaks inversion symmetry for even layer\nnumbers, making optical second harmonic generation (SHG) an ideal probe of the\ncoupling between the crystal and magnetic structures. Here, we perform magnetic\nfield and temperature-dependent SHG measurements on MnBi2Te4 flakes ranging\nfrom bulk to monolayer thickness. We find that the dominant SHG signal from\nMnBi2Te4 is unexpectedly unrelated to both magnetic state and layer number. We\nsuggest that surface SHG is the likely source of the observed strong SHG, whose\nsymmetry matches that of the MnBi2Te4-vacuum interface. Our results highlight\nthe importance of considering the surface contribution to inversion\nsymmetry-breaking in van der Waals centrosymmetric magnets.",
        "positive": "Deformation Mechanisms in High Entropy Alloys: A Minireview of\n  Short-Range Order Effects: The complex atomic scale structure of high entropy alloys presents new\nopportunities to expand the deformation theories of mechanical metallurgy. In\nthis regard, solute-defect interactions have emerged as critical piece in\nelucidating the operation of deformation mechanisms. While notable progress has\nbeen made in understanding solute-defect interactions for random solute\narrangements, recent interest in high entropy alloys with short-range order\nadds a new layer of structural complexity for which a cohesive picture has yet\nto emerge. To this end, this minireview synthesizes the current understanding\nof short-range order effects on defect behavior through an examination of the\nkey recent literature. This analysis centers on the nanoscale metallurgy of\ndeformation mechanisms, with the order-induced changes to the relevant defect\nenergy landscapes serving as a touchstone for discussion. The topics reviewed\ninclude dislocation-mediated strengthening, twinning and phase\ntransformation-based mechanisms, and vacancy-mediated processes. This\nminireview concludes with remarks on current challenges and opportunities for\nfuture efforts."
    },
    {
        "anchor": "Microstructural and dielectric properties of Ba0.6Sr0.4Ti1-xZrxO3 based\n  combinatorial thin film capacitors library: Epitaxial growth of Ba0.6Sr0.4Ti1-xZrxO3 (0/leqx\\leq0.3) composition spread\nthin film library on SrRuO3/SrTiO3 layer by combinatorial pulsed laser\ndeposition (PLD) is reported. X-ray diffraction and energy dispersive x-ray\nspectroscopy studies showed an accurate control of the film phase and\ncomposition by combinatorial PLD. A complex evolution of the microstructure and\nmorphology with composition of the library is described, resulting from the\ninterplay between epitaxial stress, increased chemical pressure and reduced\nelastic energy upon Zr doping. Statistical and temperature-related capacitive\nmeasurements across the library showed unexpected variations of the dielectric\nproperties. Doping windows with enhanced permittivity and tunability are\nidentified, and correlated to microstructural properties.",
        "positive": "Two-dimensional tetramer-cuprate Na5RbCu4(AsO4)4Cl2: phase transitions\n  and AFMorder as seen by 87Rb NMR: We report the Rb nuclear magnetic resonance (NMR) results in a recently\nsynthesized Na5RbCu4(AsO4)Cl2. This complex novel two-dimensional (2D) cuprate\nis an unique magnetic material, which contains layers of coupled Cu4O4\ntetramers. In zero applied magnetic field, it orders antiferromagnetically via\na second-order low-entropy phase transition at TN = 15(1) K. We characterise\nthe ordered state by 87Rb NMR, and suggest for it a noncollinear rather than\ncollinear arrangement of spins. We discuss the properties of Rb nuclear site\nand point out the new structural phase transition(s) around 74 K and 110 K."
    },
    {
        "anchor": "Determining electronic properties from L-edge X-ray absorption spectra\n  of transition metal compounds with artificial neural networks: X-ray absorption spectroscopy at the L-edge probes transitions of\n2p-electrons into unoccupied d-states. Applied to transition metal atoms, this\nexperimental technique can provide valuable information about the electronic\nstructure of d-states. However, multiplet effects, spin-orbit coupling, a large\nnumber of possible transitions can cause a rather involved nature of 2p XAS\nspectra, which can often complicate extracting of information directly from\nthem. Here, artificial neural networks trained on simulated spectra of a 2p XAS\nmodel Hamiltonian are presented that can directly determine information about\natomic properties and the electronic configuration of d-states from L-edge\nX-ray absorption spectra. Moreover, the adaptable nature of artificial neural\nnetworks (ANNs) allows extending their capability to obtain information about\nthe electronic ground state and core hole lifetimes from 2p XAS spectra as well\nas to incorporate external factors, such as temperature and experimental\nconvolution that can affect details in spectral features. The effects of noise\nand background contributions in spectra on the accuracy of ANNs are discussed\nand the method is validated on experimental spectra of transition metal\ncompounds, including metal-organic molecules and metal oxides.",
        "positive": "Shear-induced particle diffusivities from numerical simulations: Using Stokesian dynamics simulations, we examine the flow of a monodisperse,\nneutrally buoyant, homogeneous suspension of non-Brownian solid spheres in\nsimple shear, starting from a large number of independent hard-sphere\ndistributions and ensemble averaging the results. We construct a novel method\nfor computing the gradient diffusivity via simulations on a {\\em homogeneous}\nsuspension and, although our results are only approximate due to the small\nnumber of particles used in the simulations, we present here the first values\nof this important parameter, both along and normal to the plane of shear, which\nhave ever been obtained directly either experimentally or numerically. We show\nfurthermore that, although the system of equations describing the particle\nmotions is deterministic, the particle displacements in the two directions\nnormal to the bulk flow have Gaussian distributions with zero mean and, a\nvariance which eventually grows linearly in time thereby establishing that the\nsystem of particles is diffusive. In addition we show that although the\nparticle evolution equations are, in principle, reversible, the suspension has\nin fact a finite correlation time $T_c$ of the order of the inverse shear rate.\nFor particle concentrations up to 45%, we compute the corresponding tracer\ndiffusivities both from the slope of the mean square particle displacement as\nwell as by integrating the corresponding velocity autocorrelations and find\ngood agreement between the two sets of results."
    },
    {
        "anchor": "Machine-learning guided discovery of a high-performance spin-driven\n  thermoelectric material: Thermoelectric conversion using Seebeck effect for generation of electricity\nis becoming an indispensable technology for energy harvesting and smart thermal\nmanagement. Recently, the spin-driven thermoelectric effects (STEs), which\nemploy emerging phenomena such as the spin-Seebeck effect (SSE) and the\nanomalous Nernst effect (ANE), have garnered much attention as a promising path\ntowards low cost and versatile thermoelectric technology with easily scalable\nmanufacturing. However, progress in development of STE devices is hindered by\nthe lack of understanding of the mechanism and materials parameters that govern\nthe STEs. To address this problem, we enlist machine learning modeling to\nestablish the key physical parameters controlling SSE. Guided by these models,\nwe have carried out a high-throughput experiment which led to the\nidentification of a novel STE material with a thermopower an order of magnitude\nlarger than that of the current generation STE devices.",
        "positive": "Strain engineering of epitaxial oxide heterostructures beyond substrate\n  limitations: The limitation of commercially available single-crystal substrates and the\nlack of continuous strain tunability preclude the ability to take full\nadvantage of strain engineering for further exploring novel properties and\nexhaustively studying fundamental physics in complex oxides. Here we report an\napproach for imposing continuously tunable, large epitaxial strain in oxide\nheterostructures beyond substrate limitations by inserting an interface layer\nthrough tailoring its gradual strain relaxation. Taking BiFeO3 as a model\nsystem, we demonstrate that the introduction of an ultrathin interface layer\nallows the creation of a desired strain that can induce phase transition and\nstabilize a new metastable super-tetragonal phase as well as morphotropic phase\nboundaries overcoming substrate limitations. Furthermore, continuously tunable\nstrain from tension to compression can be generated by precisely adjusting the\nthickness of the interface layer, leading to the first achievement of\ncontinuous O-R-T phase transition in BiFeO3 on a single substrate. This\nproposed route could be extended to other oxide heterostructures, providing a\nplatform for creating exotic phases and emergent phenomena."
    },
    {
        "anchor": "Freezing-out of heavy isotopes of Kr: The separation of isotopes of natural Krypton at the gas-liquid and\nliquid-solid phase interfaces was studied under nonequilibrium conditions using\na cryogenic cell and mass spectrometry. The formation of condensate upon\ncooling Kr from the ambient temperature begins at an equilibrium temperature,\nwhich corresponds to the partial pressure of the dominant isotope 84Kr, and is\naccompanied by depletion of the gas phase 84Kr with a separation coefficient of\n~0.92; but the isotopic composition returns to the original under conditions\nclose to equilibrium. The formation of a solid phase near the freezing point is\naccompanied by depletion of the gas phase by heavy isotopes. The separation\ncoefficients 86Kr and 84Kr are ~2 and ~12, respectively, when ~3.2% of the\natoms pass into the solid phase. The solid phase with its fraction below 8.8%,\n5.8% and 5.7% does not contain 80Kr, 82Kr and 83Kr with separation coefficients\nabove ~90, ~110 and ~70, respectively, to compensate for the enrichment of the\ngas and liquid phases. Pressure-selective condensation can be used to separate\ncomponents with close boiling points when distillation and\ntemperature-selective condensation methods are ineffective, and freezing-out of\nheavy isotopes can be used to enrich elements with practically important\nisotopes.",
        "positive": "Eliminating edge electronic and phonon states of phosphorene nanoribbon\n  by unique edge reconstruction: Edge termination plays a vital role in determining the properties of 2D\nmaterials. By performing compelling ab initio simulations, a lowest-energy\nU-edge [ZZ(U)] reconstruction is revealed in the bilayer phosphorene. Such\nreconstruction reduces 60% edge energy compared with the pristine one and\noccurs almost without energy barrier, implying it should be the dominating edge\nin reality. The electronic band structure of phosphorene nanoribbon with such\nreconstruction resembles that of intrinsic 2D layer, exhibiting nearly edgeless\nband characteristics. Although ZZ(U) changes the topology of phosphorene\nnanoribbon (PNR), simulated TEM, STEM and STM images indicates it is very hard\nto be identified. One possible identify method is IR/Raman analyses because\nZZ(U) edge alters vibrational modes dramatically. Beyond, it also increases the\nthermal conductivity of PNR 1.4 and 2.3 times than the pristine and Klein\nedges."
    },
    {
        "anchor": "Effect of W alloying on the electronic structure, phase stability and\n  thermoelectric properties of epitaxial CrN films: The effects of W alloying on the electronic structure, phase stability, and\nthermoelectric properties of Cr1-xWxN films with 0 \\leq x \\leq 0.48 are\nreported. Ab initio calculations indicate that dilute W alloying (x = 0.03)\nresults in flat bands from W 5d states and pushes the Fermi level EF into the\nconduction band, while retaining dispersive Cr 3d bands. These features are\ncollectively conducive for both high electrical conductivity \\sigma and high\nSeebeck coefficient \\alpha. Epitaxial Cr1-xWxN films grown on c-plane sapphire\nby dc-magnetron sputtering show that \\sigma increases with W additions of x\n\\leq 0.2. Higher W levels results in the formation of metallic Cr2N and W\nprecipitation, yielding high \\sigma but low \\alpha. These findings suggest that\nrestricting the W level to below its solubility limit in CrN is key to\nrealizing high thermoelectric properties in Cr1-xWxN alloys.",
        "positive": "Modeling the Ga/As binary system across temperaturesand compositions\n  from first principles: Materials composed of elements from the third and fifth columns of the\nperiodic table display a very rich behavior, with the phase diagram usually\ncontaining a metallic liquid phase and a polar semiconducting solid. As a\nconsequence, it is very hard to achieve transferable empirical models of\ninteractions between the atoms that can reliably predict their behavior across\nthe temperature and composition range that is relevant to the study of the\nsynthesis and properties of III/V nanostructures and devices. We present a\nmachine-learning potential trained on density functional theory reference data\nthat provides a general-purpose model for the Ga$_x$As$_{1-x}$ system. We\nprovide a series of stringent tests that showcase the accuracy of the\npotential, and its applicability across the whole binary phase space, computing\nwith ab initio accuracy a large number of finite-temperature properties as well\nas the location of phase boundaries. We also show how a committe model can be\nused to reliably determine the uncertainty induced by the limitations of the ML\nmodel on its predictions, to identify regions of phase space that are predicted\nwith insufficient accuracy, and to iteratively refine the training set to\nachieve consistent, reliable modeling."
    },
    {
        "anchor": "Phonon Coupled Scattering Caused Ultralow Lattice Thermal Conductivity\n  and Its Role in The Remarkable Thermoelectric Performance of Newly Predicted\n  SiS2 and SiSe2 monolayers: For high efficiency thermoelectric power conversion not only improvement of\nmaterials properties but also prediction and synthesis of new thermoelectric\nmaterials is needed. Here we have carried out a systematic investigation on\nthermoelectric performance of newly predicted two dimensional (2D)\nsemiconducting SiS2 and SiSe2 monolayers of group IVA-VIA family using density\nfunctional theory (DFT) and Boltzmann transport equation (BTE). Our computed\nvalues of lattice thermal conductivity (kph) are ultralow which result very\nhigh thermoelectric figure of merit (ZT) value of 0.78 (0.80) at 500K in SiS2\n(SiSe2) monolayer. The ultralow values of kph are attributed to phonon-phonon\ncoupling of acoustic and low frequency optical branches which leads to larger\nscattering, low group velocity, smaller mean free path and shorter lifetime of\nphonons. It is also found from our investigation that p-type doping is more\neffective than n-type doping to get optimal power factor (PF) and ZT. Our\ntheoretical investigation suggests that newly predicted semiconducting SiS2 and\nSiSe2 monolayers can be very promising thermoelectric materials for fabrication\nof high efficiency thermoelectric power generator to convert wastage heat into\nelectricity.",
        "positive": "Ferromagnet proximity effects and magnetoresistance of bilayer graphene: A drastic modification of electronic band structure is predicted in bilayer\ngraphene when it is placed between two ferromagnetic insulators. Due to the\nexchange interaction with the proximate ferromagnet, the electronic energy\ndispersion in the graphene channel strongly depends on the magnetization\norientation of two ferromagnetic layers, $\\mathbf{M_{1}}$ and $\\mathbf{M_{2}}\n$. While the parallel configuration $\\mathbf{M_{1}}= \\mathbf{M_{2}}$ leads to\nsimple spin splitting of both conduction and valence bands, an energy gap is\ninduced as soon as the angle $\\theta$ between $\\mathbf{M_{1}}$ and $%\n\\mathbf{M_{2}}$ becomes non-zero with the maximum achieved at $\\theta=\\pi$\n(i.e., antiparallel alignment). Consequently, bilayer graphene may exhibit a\nsizable magnetoresistive effect in the current-in-plane configuration. A rough\nestimate suggests the resistance changes on the order of tens of percent at\nroom temperature. This effect is expected to become more pronounced as the\ntemperatures decreases."
    },
    {
        "anchor": "Near Unity Molecular Doping Efficiency in Monolayer MoS2: Surface functionalization with organic electron donors (OEDs) is an effective\ndoping strategy for two-dimensional (2D) materials, which can achieve doping\nlevels beyond those possible with conventional electric field gating. While the\neffectiveness of surface functionalization has been demonstrated in many 2D\nsystems, the doping efficiencies of OEDs have largely been unmeasured, which is\nin stark contrast to their precision syntheses and tailored redox potentials.\nHere, using monolayer MoS2 as a model system and an organic reductant based on\n4,4-bipyridine (DMAP-OED) as a strong organic dopant, we establish that the\ndoping efficiency of DMAP-OED to MoS2 is in the range of 0.63 to 1.26 electrons\nper molecule. We also achieve the highest doping level to date in monolayer\nMoS2 by surface functionalization and demonstrate that DMAP-OED is a stronger\ndopant than benzyl viologen, which was the previous best OED dopant. The\nmeasured range of the doping efficiency is in good agreement with the values\npredicted from first-principles calculations. Our work provides a basis for the\nrational design of OEDs for high-level doping of 2D materials.",
        "positive": "Optical pulse induced ultrafast antiferrodistortive transition in SrTiO3: The ultrafast dynamics of the antiferrodistortive (AFD) phase transition in\nperovskite SrTiO3 is monitored via time-domain Brillouin scattering. Using\nfemtosecond optical pulses, we induce a thermally driven tetragonal-to-cubic\nstructural transformation and detect notable changes in the frequency of\nBrillouin oscillations (BO) induced by propagating acoustic phonons. First, we\nestablish a fingerprint frequency of different regions across the temperature\nphase diagram of the AFD transition characterized by tetragonal and cubic\nphases in the low and high temperature sides, respectively. Then, we\ndemonstrate that in a sample nominally kept in tetragonal phase, deposition of\nsufficient thermal energy induces an instantaneous transformation of the\nheat-affected region to the cubic phase. Coupling the measured depth-resolved\nBO frequency with a time and depth-resolved heat diffusion model, we detect a\nreverse cubic-to-tetragonal phase transformation occurring on a time scale of\nhundreds of picoseconds. We attribute this ultrafast phase transformation in\nthe perovskite to a structural resemblance between atomic displacements of the\nR-point soft optic mode of the cubic phase and the tetragonal phase, both\ncharacterized by anti-phase rotation of oxygen octahedra. Evidence of such a\nfast structural transition in perovskites can open up new avenues in the field\nof information processing and energy storage."
    },
    {
        "anchor": "Nucleation of Al3Zr and Al3Sc in aluminum alloys: from kinetic Monte\n  Carlo simulations to classical theory: Zr and Sc precipitate in aluminum alloys to form the compounds Al3Zr and\nAl3Sc which for low supersaturations of the solid solution have the L12\nstructure. The aim of the present study is to model at an atomic scale this\nkinetics of precipitation and to build a mesoscopic model based on classical\nnucleation theory so as to extend the field of supersaturations and annealing\ntimes that can be simulated. We use some ab-initio calculations and\nexperimental data to fit an Ising model describing thermodynamics of the Al-Zr\nand Al-Sc systems. Kinetic behavior is described by means of an atom-vacancy\nexchange mechanism. This allows us to simulate with a kinetic Monte Carlo\nalgorithm kinetics of precipitation of Al3Zr and Al3Sc. These kinetics are then\nused to test the classical nucleation theory. In this purpose, we deduce from\nour atomic model an isotropic interface free energy which is consistent with\nthe one deduced from experimental kinetics and a nucleation free energy. We\ntest di erent mean-field approximations (Bragg-Williams approximation as well\nas Cluster Variation Method) for these parameters. The classical nucleation\ntheory is coherent with the kinetic Monte Carlo simulations only when CVM is\nused: it manages to reproduce the cluster size distribution in the metastable\nsolid solution and its evolution as well as the steady-state nucleation rate.\nWe also find that the capillary approximation used in the classical nucleation\ntheory works surprisingly well when compared to a direct calculation of the\nfree energy of formation for small L12 clusters.",
        "positive": "Effect of Sb substitution on the Topological Surface States in\n  Bi_{2}Se_{3} single crystals: a magneto-transport study: Magneto-transport measurements have been carried out on Bi2-xSbxSe3 (x = 0,\n0.05, 0.1, 0.3, 0.5) single crystals at 4.2 K temperature in the magnetic field\nrange of -15 T to 15 T. Shubnikov-de Haas (SdH) oscillations of 2D nature were\nobserved in samples with Sb concentration upto x = 0.3. The analyses of SdH\noscillations observed in magneto-resistance data using Lifshitz-Kosevich\nequation reveal a systematic decrease in the Fermi surface area with Sb\nsubstitution. The Berry phase obtained from the Landau Level fan diagram\nsuggests the occurrence of 2D oscillations arising from a Topological Surface\nState (TSS) for Sb concentrations of x = 0, 0.05 and 0.1; while 2D oscillation\nseen at higher Sb concentration is attributed to surface 2D electron gas\nconsequent to downward band bending."
    },
    {
        "anchor": "Sensing of DNA conformation based on change in FRET efficiency between\n  laser dyes: This communication reports the effect of DNA conformation on fluorescence\nresonance energy transfer (FRET) efficiency between two laser dyes in layer by\nlayer (LbL) self assembled film. The dyes Acraflavine and Rhodamine B were\nattached onto the negative phosphate backbones of DNA in LbL film through\nelectrostatic attraction. Then FRET between these dyes was investigated.\nIncrease in pH or temperature causes the denaturation of DNA followed by coil\nformation of single stranded DNA. As a result the FRET efficiency also changed\nalong with it. These observations demonstrated that by observing the change in\nFRET efficiency between two laser dyes in presence of DNA it is possible to\ndetect the altered DNA conformation in the changed environment.",
        "positive": "Comparison of GW band structure to semi-empirical approach for an FeSe\n  monolayer: We present the G$_0$W$_0$ band structure, core levels, and deformation\npotential of monolayer FeSe in the paramagnetic phase based on a starting mean\nfield of the Kohn Sham density functional theory (DFT) with the PBE functional.\nWe find the GW correction increases the bandwidth of the states forming the $M$\npocket near the Fermi energy, while leaving the $\\Gamma$ pocket roughly\nunchanged. We then compare the G$_0$W$_0$ quasiparticle band energies with the\nband structure from a simple empirical +A approach, which was recently proposed\nto capture the renormalization of the electron-phonon interaction going beyond\nDFT in FeSe, when used as a starting point in density functional perturbation\ntheory (DFPT). We show that this empirical correction succeeds in approximating\nthe GW non-local and dynamical self energy in monolayer FeSe and reproduces the\nGW band structure near the Fermi surface, the core energy levels, and the\ndeformation potential (electron-phonon coupling)."
    },
    {
        "anchor": "CrSbSe3: a pseudo one-dimensional ferromagnetic semiconductor: Low-dimensional magnetic materials have attracted much attention due to their\nnovel properties and high potential for spintronic applications. In this work,\nwe study the electronic structure and magnetic properties of the pseudo\none-dimensional compound CrSbSe$_3$, using density functional calculations,\nsuperexchange model analyses, and Monte Carlo simulations. We find that\nCrSbSe$_3$ is a ferromagnetic (FM) semiconductor with a band gap of about 0.65\neV. The FM couplings within each zig-zag spin chain are due to the Cr-Se-Cr\nsuperexchange with the near-90$^\\circ$ bonds, and the inter-chain FM couplings\nare one order of magnitude weaker. By inclusion of the spin-orbit coupling\n(SOC) effects, our calculations reproduce the experimental observation of the\neasy magnetization $a$ axis and the hard $b$ axis (the spin-chain direction),\nwith the calculated moderate magnetic anisotropy of 0.19 meV/Cr. Moreover, we\nidentify the nearly equal contributions from the single ion anisotropy of Cr,\nand from the exchange anisotropy due to the strong SOC of the heavy elements Sb\nand Se and their couplings with Cr. Using the parameters of the magnetic\ncoupling and anisotropy from the above calculations, our Monte Carlo\nsimulations yield the Curie temperature $T_{\\rm{C}}$ of 108 K.",
        "positive": "Stabilized Interfacial Ferromagnetism and Enhanced Magnetoelectric\n  Properties of Ultrathin FeRh Films Capped with Heavy Transition Metal Ta: Thin FeRh film was extensively studied recently, and an emergent substrate-\nand capping-dependent interfacial ferromagnetism (FM) was widely observed in\nexperiments. However, the voltage modulation of this interfacial ferromagnetism\nis barely studied, which would have profound applications in antiferromagnetic\n(AFM) FeRh-based magnetoelectric-random access memory (MeRAM). Using ab initio\ntechniques, we comparatively study the interfacial ferromagnetic properties and\nmagnetoelectric responses of ultrathin FeRh films capped by heavy transition\nmetal Ta. We find that Ta capping reverses the phase stability of ultrathin\nFeRh film below 1.5 nm and gigantically stabilizes the ferromagnetic phase and\ninterfacial ferromagnetism. Besides, small magnetic moment of 2.2 $\\mu_B$ for\nneighboring Fe atoms, regardless of magnetic configurations and film thickness,\nis induced by Ta capping. Compared with FeRh/MgO bilayers, magnetic\nanisotropies (in-plane for AFM, perpendicular for FM and interfacial-FM\nreconstructed trilayers) and magnetoelectric responses of these trilayers are\nenhanced. Furthermore, the VCMA behavior in FM phase is changed from\n$\\vee$-shaped to linear. These findings demonstrate the manipulation of\nmagnetic ordering of FeRh films with heavy metal capping and electric field and\ncan promote the application of FeRh alloy in magnetic memory and\nantiferromagnetic spintronics."
    },
    {
        "anchor": "Graphite Nanoeraser: We present here a method for cleaning intermediate-size (5~50nm)\ncontamination from highly oriented pyrolytic graphite. Electron beam deposition\ncauses a continuous increase of carbonaceous material on graphene and graphite\nsurfaces, which is difficult to remove by conventional techniques. Direct\nmechanical wiping using a graphite nanoeraser is observed to drastically reduce\nthe amount of contamination. After the mechanical removal of contamination, the\ngraphite surfaces were able to self-retract after shearing, indicating that van\nder Waals contact bonding is restored. Since contact bonding provides an\nindication of a level of cleanliness normally only attainable in a high-quality\nclean-room, we discuss potential applications in preparation of ultraclean\nsurfaces.",
        "positive": "Determinants of local chemical environments and magnetic moments of\n  high-entropy alloys: High-entropy alloys (HEAs) such as CrMnFeCoNi exhibit unconventional\nmechanical properties due to their compositional disorder. However, it remains\na formidable challenge to estimate the local chemical-environment and magnetic\neffects of HEAs. Herein we identify the state-associated cohesive energy and\nband filling originated from the tight-binding and Friedel models as\ndescriptors to quantify the site-to-site chemical bonding and magnetic moments\nof HEAs. We find that the s-state cohesive energy is indispensable in\ndetermining the bonding-strength trend of CrMnFeCoNi that differs from the\nbonding characteristics of precious and refractory HEAs, while the s-band\nfilling is effective in determining the magnetic moments. This unusual behavior\nstems from the unique chemical and magnetic nature of Cr atoms and is\nessentially due to the localized and transferred itinerant electrons. Our study\nestablishes a fundamental physical picture of chemical bonding and magnetic\ninteractions of HEAs and provides a rational guidance for designing advanced\nstructural alloys."
    },
    {
        "anchor": "Electric-field-induced magnetization changes in Co/Al2O3 granular\n  multilayers: We study experimentally the effect of electric field on the magnetization of\nCo/Al2O3 granular multilayers. We observe two distinct regimes: (a) low-field\nregime when the net magnetization of the system changes in a reversible way\nwith the applied electric field and (b) high-field regime when the\nmagnetization decreases irreversibly. The former is attributed to the changes\nin the relative 3d-orbital occupation of the minority and majority bands in the\nCo granules. A theoretical model has been developed to explain the electric\nfield induced changes in the band structure of the granular system and hence\nthe magnetic moment. The latter result may be understood assuming the electric\nfield induces oxygen migration from Al2O3 to the Co granules, since an increase\nin oxidation state of the Co granules is shown, through ab-initio calculations,\nto give rise to a reduced magnetization of the system.",
        "positive": "Probing the Free-carrier Absorption in Multi-Layer Black Phosphorus: We study the carrier relaxation dynamics in thin black phosphorus (bP) using\ntime-resolved differential transmission measurements. The inter-band and\nintra-band transitions, relaxation, and carrier recombination lifetimes are\nrevealed by tuning the mid-infrared probe wavelength above and below the\nbandgap of black phosphorus. When the probe energy exceeds the bandgap, Pauli\nblocked inter-band transitions are observed. The differential transmission\nsignal changes sign from positive to negative when the probe energy is below\nthe bandgap, due to the absence of inter-band transitions and enhancement in\nthe free-carrier absorption (FCA). The minority carrier lifetime and radiative\nrecombination coefficient are estimated 1.3 ns, and 5.9$\\rm \\times 10^{-10}$\n$\\rm cm^{3}/s$, respectively. The overall recombination lifetime of bP is\nlimited by radiative recombination for excess carrier densities larger than\n5$\\rm \\times 10^{19}$ $\\rm cm^{-3}$."
    },
    {
        "anchor": "On the importance of prismatic/basal interfaces in the growth of (-1012)\n  twins in hexagonal close-packed crystals: The growth process of of (-1012) twins is studied in Magnesium using\natomistic simulations. Two twin seeds are considered and both cases, a specific\ninterface, which places face-to-face prismatic and basal planes, plays an\nimportant role. This interface has a low energy corresponding to a cusp in the\norientation-dependent interface energy of a twinned bicrystal. This interface\nappears in several published twin structures and for instance accommodates the\nlarge deviations of twin interfaces from (-1012) planes reported recently\n[Zhang et al., Scr. Mater. 67 (2012) 862].",
        "positive": "A robust and efficient line search for self-consistent field iterations: We propose a novel adaptive damping algorithm for the self-consistent field\n(SCF) iterations of Kohn-Sham density-functional theory, using a backtracking\nline search to automatically adjust the damping in each SCF step. This line\nsearch is based on a theoretically sound, accurate and inexpensive model for\nthe energy as a function of the damping parameter. In contrast to usual damped\nSCF schemes, the resulting algorithm is fully automatic and does not require\nthe user to select a damping. We successfully apply it to a wide range of\nchallenging systems, including elongated supercells, surfaces and\ntransition-metal alloys."
    },
    {
        "anchor": "Impact of the La2NiO4+\u03b4 oxygen content on the synaptic properties\n  of the TiN/La2NiO4+\u03b4/Pt memristive devices: The rapid development of brain-inspired computing requires new artificial\ncomponents and architectures for its hardware implementation. In this regard,\nmemristive devices emerged as potential candidates for artificial synapses\nbecause of their ability to emulate the plasticity of the biological synapses.\nIn this work, the synaptic behavior of the TiN/La2NiO4+{\\delta}/Pt memristive\ndevices based on thermally annealed La2NiO4+{\\delta} films is thoroughly\ninvestigated. Using electron energy loss spectroscopy, we show that annealing\nusing reducing (Ar) or oxidizing (O2) atmospheres affects the interstitial\noxygen content ({\\delta}) in the La2NiO4+{\\delta} films. Electrical\ncharacterization shows that both devices exhibit long-term\npotentiation/depression and spike-timing-dependent plasticity, which makes them\nsuitable for neuromorphic applications. At the same time, the Ar annealed\nTiN/La2NiO4+{\\delta}/Pt device demonstrates non-volatile properties with low\nenergy consumption during the learning process. On the other hand, in the O2\nannealed TiN/La2NiO4+{\\delta}/Pt device the resistive switching behavior is\nmore volatile and requires more energy for synaptic learning. Finally, the\nsimulation tools show that spiking neural network architectures with\nunsupervised learning rules based on the experimental data achieve high\ninference accuracy in the digit recognition task, which proves the potential of\nTiN/La2NiO4+{\\delta}/Pt devices for artificial synapse applications.",
        "positive": "Ferromagnetism in semiconductors and oxides: prospects from a ten years'\n  perspective: Over the last decade the search for compounds combining the resources of\nsemiconductors and ferromagnets has evolved into an important field of\nmaterials science. This endeavour has been fuelled by continual demonstrations\nof remarkable low-temperature functionalities found for ferromagnetic\nstructures of (Ga,Mn)As, p-(Cd,Mn)Te, and related compounds as well as by ample\nobservations of ferromagnetic signatures at high temperatures in a number of\nnon-metallic systems. In this paper, recent experimental and theoretical\ndevelopments are reviewed emphasising that, from the one hand, they disentangle\nmany controversies and puzzles accumulated over the last decade and, on the\nother, offer new research prospects."
    },
    {
        "anchor": "Impressive optoelectronic and thermoelectric properties of\n  two-dimensional XI$_2$ (X=Sn, Si): a first principle study: Two-dimensional (2D) metal halides have received more attention because of\ntheir electronic and optoelectronic properties. Recently, researchers are\ninterested to investigate the thermoelectric properties of metal halide\nmonolayers because of their ultralow lattice conductivity, high Seebeck\ncoefficient and figure of merit. Here, we have investigated thermoelectric and\noptoelectronic properties of XI$_2$ (X=Sn and Si) monolayers with the help of\ndensity functional theory and Boltzmann transport equation. The structural\nparameters have been optimized with relaxation of atomic positions. Excellent\nthermoelectric and optical properties have been obtained for both SnI$_2$ and\nSiI$_2$ monolayers. For SnI$_2$ an indirect bandgap of 2.06 eV was observed and\nthe absorption peak was found at 4.68 eV. For this the highest ZT value of 0.84\nfor p-type doping at 600K has been calculated. Similarly, for SiI$_2$ a\ncomparatively low indirect bandgap of 1.63 eV was observed, and the absorption\npeak was obtained at 4.86 eV. The calculated ZT product for SiI$_2$ was 0.87 at\n600K. Both the crystals having high absorbance and ZT value suggest that they\ncan be promising candidates for optoelectronic and thermoelectric devices.",
        "positive": "Superior mechanical flexibility of phosphorene and few-layer black\n  phosphorus: Recently fabricated two dimensional (2D) phosphorene crystal structures have\ndemonstrated great potential in applications of electronics. Mechanical strain\nwas demonstrated to be able to significantly modify the electronic properties\nof phosphorene and few-layer black phosphorus. In this work, we employed first\nprinciples density functional theory calculations to explore the mechanical\nproperties of phosphorene, including ideal tensile strength and critical\nstrain. It was found that a monolayer phosphorene can sustain tensile strain up\nto 27% and 30% in the zigzag and armchair directions, respectively. This\nenormous strain limit of phosphorene results from its unique puckered crystal\nstructure. We found that the tensile strain applied in the armchair direction\nstretches the pucker of phosphorene, rather than significantly extending the\nP-P bond lengths. The compromised dihedral angles dramatically reduce the\nrequired strain energy. Compared to other 2D materials such as graphene,\nphosphorene demonstrates superior flexibility with an order of magnitude\nsmaller Young modulus. This is especially useful in practical\nlarge-magnitude-strain engineering. Furthermore, the anisotropic nature of\nphosphorene was also explored. We derived a general model to calculate the\nYoung modulus along different directions for a 2D system."
    },
    {
        "anchor": "Phase stability and lattice dynamics of ammonium azide under hydrostatic\n  compression: We have investigated the effect of hydrostatic pressure and temperature on\nphase stability of hydro-nitrogen solids using dispersion corrected Density\nFunctional Theory calculations. From our total energy calculations, Ammonium\nAzide (AA) is found to be the thermodynamic ground state of N$_4$H$_4$\ncompounds in preference to Trans-Tetrazene (TTZ), Hydro-Nitrogen Solid-1\n(HNS-1) and HNS-2 phases. We have carried out a detailed study on structure and\nlattice dynamics of the equilibrium phase (AA). AA undergoes a phase transition\nto TTZ at around $\\sim$ 39-43 GPa followed by TTZ to HNS-1 at around 80-90 GPa\nunder the studied temperature range of 0-650 K. The accelerated and decelerated\ncompression of $a$ and $c$ lattice constants suggest that the ambient phase of\nAA transforms to a tetragonal phase and then to a low symmetry structure with\nless anisotropy up on further compression. We have noticed that the angle made\nby Type-II azides with $c$-axis shows a rapid decrease and reaches a minimum\nvalue at 12 GPa, and thereafter increases up to 50 GPa. Softening of the shear\nelastic moduli is suggestive of a mechanical instability of AA under high\npressure. In addition, we have also performed density functional perturbation\ntheory calculations to obtain the vibrational spectrum of AA at ambient as well\nas at high pressures. Further, we have made a complete assignment of all the\nvibrational modes which is in good agreement with the experimental observations\nat ambient pressure. Also the calculated pressure dependent IR spectra show\nthat the N-H stretching frequencies undergo a red and blue-shift corresponding\nto strengthening and weakening of hydrogen bonding, respectively below and\nabove 4 GPa.",
        "positive": "Electrostatic co-assembly of magnetic nanoparticles and fluorescent\n  nanospheres: a versatile approach toward bimodal nanorods: The elaboration of multimodal nanoparticles stimulates tremendous interest\nowing to their numerous potentialities in many applicative fields like\noptoelectronics, photonics and especially bioimaging. The concomitant\nassociation of various properties (optical, electrochemical, magnetic) allows\nfor the use of complementary stimuli in order to probe the interactions between\nthe nanoparticles and their surroundings.Nanoparticles (NPs) have thus become\nhighly praised tools to image cells and tissues with a large contrast\ncompatible with the dimensions of biological materials and the existence of\nquantum confinement effects induced by the reduced dimensions. In this context,\nthe combination of magnetism and emissive properties such as fluorescence\nappears particularly attractive for non-invasive investigations, cell sorting\nor drug vectorization. Therefore, combining both fluorescence and magnetism\nrequires the delicate construction of hybrid assemblies. Most of the magnetic\nnanoparticles are made of metallic oxides or alloys, e.g. gamma-Fe2O3, Fe3O4,\nFePt, while the target fluorescent entities are often organic dyes or quantum\ndots (QDs)."
    },
    {
        "anchor": "Self-selecting vapor growth of transition metal halide single crystals: Transition metal halides can host a large variety of novel phenomena, such as\nmagnetism in the monolayer limit, quantum spin liquid and spiral spin liquid\nstates, and topological magnons and phonons. Sizeable high quality single\ncrystals are necessary for investigations of magnetic and lattice excitations\nby, for example, inelastic neutron scattering. In this paper, we review a less\nwell-known vapor transport technique, self-selecting vapor growth, and report\nour growths of transition metal halides using this technique. We report the\ngrowth and characterizations of sizable single crystals of RuCl$_3$, CrCl$_3$,\nRu$_{1-x}$Cr$_x$Cl$_3$, and CrBr$_3$. In order to expedite the conversion of\nstarting powder to single crystals, we modified the technique by cooling the\ngrowth ampoule through an appropriate temperature range. Our work shows that\nthe self-selecting vapor transport technique can provide large single crystals\nof transition metal halides, demonstrating its potential for providing high\nquality single crystals of quantum materials.",
        "positive": "Brittle fracture studied by ultra-high speed synchrotron X-ray\n  diffraction imaging: Ever since the very first human-made knapped tools, the control of fracture\npropagation in brittle materials has been a vector of technological\ndevelopment. Nowadays, a broad range of applications relies on crack\npropagation control, from the mitigation of damages, e.g., from impacts in\nglass screens or windshields, to industrial processes harnessing fracture to\nachieve clean cuts over large distances. Yet, studying the fracture in real\ntime is a challenging task, since cracks can propagate up to a few km/s in\nmaterials that are often opaque. Here, we report on the in situ investigation\nof cracks propagating at up to 2.5 km/s along a (001) plane of a silicon single\ncrystal, using X-ray diffraction megahertz imaging with intense and\ntime-structured synchrotron radiation. The studied system is based on the Smart\nCut process, where a buried layer in a material (typically Si) is weakened by\nmicro-cracks and then used to drive a macroscopic crack (0.1 m) in a plane\nparallel to the surface with minimal deviation (1 nm). The results we report\nhere provide the first direct confirmation that the shape of the crack front is\nnot affected by the distribution of the micro-cracks, which had been a\npostulate for previous studies based on post-fracture results. We further\nmeasured instantaneous crack velocities over the centimeter-wide field-of-view,\nwhich had only been previously inferred from sparse point measurements, and\nevidence the effect of local heating by the X-ray beam. Finally, we also\nobserved the post-crack movements of the separated wafer parts, which can be\nexplained using pneumatics and elasticity. Thus, this study provides a\ncomprehensive view of controlled fracture propagation in a crystalline\nmaterial, paving the way for the in situ measurement of ultra-fast strain field\npropagation."
    },
    {
        "anchor": "Nuclear excitation of the $^{229}$Th isomer via defect states in doped\n  crystals: When Th nuclei are doped in CaF$_2$ crystals, a set of electronic defect\nstates appears in the crystal bandgap which would otherwise provide complete\ntransparency to vacuum-ultraviolet radiation. The coupling of these defect\nstates to the 8 eV $^{229m}$Th nuclear isomer in the CaF$_2$ crystal is\ninvestigated theoretically. We show that although previously viewed as a\nnuisance, the defect states provide a starting point for nuclear excitation via\nelectronic bridge mechanisms involving stimulated emission or absorption using\nan optical laser. The rates of these processes are at least two orders of\nmagnitude larger than direct photoexcitation of the isomeric state using\navailable light sources. The nuclear isomer population can also undergo\nquenching when triggered by the reverse mechanism, leading to a fast and\ncontrolled decay via the electronic shell. These findings are relevant for a\npossible solid-state nuclear clock based on the $^{229m}$Th isomeric\ntransition.",
        "positive": "Effect of pre-oxidation treatments on the structural, microstructural,\n  and chemical properties of (Ni,Pt)Al systems: The effect of isothermal pre-oxidation treatments on the \\b{eta}-(Ni,Pt)Al +\nRen\\'e N5 system degradation is here reported. The oxidation treatments were\ncarried out from 900 (mostly {\\theta}-Al2O3 growing conditions) to 1200{\\deg}C\n(mainly {\\alpha}-Al2O3 growing conditions) for 5 h, under a purified Ar-stream\nwith a fixed pO2= 1 x 10-5 atm. Results are discussed based on the correlation\nbetween the structural, microstructural and chemical properties of the\n\\b{eta}-(Ni,Pt)Al BC showing that pre-oxidation parameters have an important\neffect on the multi-elemental counter diffusion phenomena along BC. For\ninstance, a significant BC+IDZ thickness increase of 55% at 1200 {\\deg}C was\nobserved with respect to as-received sample just after 5 h of oxidation\nresulting in a severe BC degradation."
    },
    {
        "anchor": "High Pressure Study of Lithium Azide from Density-Functional\n  Calculations: The structural, electronic, optical and vibrational properties of LiN$_3$\nunder high pressure have been studied using plane wave pseudopotentials within\nthe generalized gradient approximation for the exchange and correlation\nfunctional. The calculated lattice parameters agree quite well with\nexperiments. The calculated bulk modulus value is found to be 23.23 GPa which\nis in good agreement with the experimental value of 20.5 GPa. Our calculations\nreproduce well the trends in high pressure behavior of the structural\nparameters. The present results show that the compressibility of LiN$_3$\ncrystal is anisotropic and the crystallographic b-axis is more compressible\nwhen compared to a- and c-axis which is also consistent with the experiment.\nThe computed elastic constants clearly shows that LiN$_3$ is a mechanically\nstable system and the calculated elastic constants follows the order C$_{33}$\n$>$ C$_{11}$ $>$ C$_{22}$ implies that the LiN$_3$ lattice is stiffer along\nc-axis and relatively weaker along b-axis. Under the application of pressure\nthe magnitude of the electronic band gap value decreases, indicating that the\nsystem has the tendency to become semi conductor at high pressures. The optical\nproperties such as refractive index, absorption spectra and photo conductivity\nalong the three crystallographic directions have been calculated at ambient as\nwell as at high pressures. The calculated refractive index shows that the\nsystem is optically anisotropic and the anisotropy increases with increase in\npressure. The observed peaks in the absorption and photo conductivity spectra\nare found to shift towards the higher energy region as pressure increases which\nimply that in LiN$_3$ decomposition is favored under pressure with the action\nof light.",
        "positive": "Observation of 2D Weyl Fermion States in Epitaxial Bismuthene: A two-dimensional (2D) Weyl semimetal featuring a spin-polarized linear band\ndispersion and a nodal Fermi surface is a new topological phase of matter. It\nis a solid-state realization of Weyl fermions in an intrinsic 2D system. The\nnontrivial topology of 2D Weyl cones guarantees the existence of a new form of\ntopologically protected boundary states, Fermi string edge states. In this\nwork, we report the realization of a 2D Weyl semimetal in monolayer-thick\nepitaxial bismuthene grown on SnS(Se) substrate. The intrinsic band gap of\nbismuthene is eliminated by the space-inversion-symmetry-breaking substrate\nperturbations, resulting in a gapless spin-polarized Weyl band dispersion. The\nlinear dispersion and spin polarization of the Weyl fermion states are observed\nin our spin and angle-resolved photoemission measurements. In addition, the\nscanning tunneling microscopy/spectroscopy reveals a pronounced local density\nof states at the edge, suggesting the existence of Fermi string edge states.\nThese results open the door for the experimental exploration of the exotic\nproperties of Weyl fermion states in reduced dimensions."
    },
    {
        "anchor": "Origin of efficient thermoelectric performance in half-Heusler\n  FeNb$_{0.8}$Ti$_{0.2}$Sb: A half-Heusler material FeNb$_{0.8}$Ti$_{0.2}$Sb has been identified as a\npromising thermoelectric material due to its excellent thermoelectric\nperformance at high temperatures. The origins of the efficient thermoelectric\nperformance are investigated through a series of low-temperature (2 - 400 K)\nmeasurements. The high data coherence of the low and high temperatures is\nobserved. An optimal and nearly temperature-independent carrier concentration\nis identified, which is ideal for the power factor. The obtained single type of\nhole carrier is also beneficial to the large Seebeck coefficient. The\nelectronic thermal conductivity is found to be comparable to the lattice\nthermal conductivity and becomes the dominant component above 200 K. These\nfindings again indicate that electron scattering plays a key role in the\nelectrical and thermal transport properties. The dimensionless figure of merit\nis thus mainly governed by the electronic properties. These effects obtained at\nlow temperatures with the avoidance of possible thermal fluctuations together\noffer the physical origin for the excellent thermoelectric performance in this\nmaterial.",
        "positive": "Adding anisotropy to the standard quasi-harmonic approximation still\n  fails in several ways to capture organic crystal thermodynamics: We evaluate the accuracy of varying thermal expansion models for the\nquasi-harmonic approximation (QHA) relative to molecular dynamics (MD) for 10\nsets of enantiotropic organic polymorphs. Relative to experiment we find that\nMD, using an off-the-shelf point charge potential gets the sign of the\nenthalpic contributions correct for 6 of the 10 pairs of polymorphs and the\nsign of the entropic contributions correct for all pairs. We find that\nanisotropic QHA provides little improvement to the error in free energy\ndifferences from MD relative to isotropic QHA, but does a better job capturing\nthe thermal expansion of the crystals. A form of entropy-enthalpy compensation\nallows the free energy differences of QHA to deviate less than 0.1 kcal/mol\nfrom MD for most polymorphic pairs, despite errors up to 0.4 kcal/mol in the\nentropy and enthalpy. Much of the error previously found between QHA and MD for\nthese flexible molecules is reduced when QHA is run from a lattice minimum\nconsistent with the same basin as MD, rather than the energy-minimized\nexperimental crystal structure. Specifically, performing anisotropic QHA on\nlattice minimum quenched from low-temperature replica exchange simulations\nreduced the error previously found by 0.2 kcal/mol on average. However, these\nconformationally flexible molecules can have many low-temperature\nconformational minima, and the choice of an inconsistent minima causes free\nenergies estimated from QHA to deviate from MD at temperatures as low as 10 K.\nThe errors between MD and experiment are 1-2 orders of magnitude larger than\nthose seen between QHA and MD, so the quality of the force field used is still\nof primary concern, but this study illustrates a number of other important\nfactors that must be considered to obtain quantitative organic crystal\nthermodynamics."
    },
    {
        "anchor": "Determining the energetics of vicinal perovskite oxide surfaces: The energetics of vicinal SrTiO$_3$(001) and DyScO$_3$(110), prototypical\nperovskite vicinal surfaces, has been studied using topographic atomic force\nmicroscopy imaging. The kink formation and strain relaxation energies are\nextracted from a statistical analysis of the step meandering. Both perovskite\nsurfaces have very similar kink formation energies and exhibit a similar\ntriangular step undulation. Our experiments suggest that the energetics of\nperovskite oxide surfaces is mainly governed by the local oxygen coordination.",
        "positive": "The Dynamics of Rapid Fracture: Instabilities, Nonlinearities and Length\n  Scales: The failure of materials and interfaces is mediated by cracks, nearly\nsingular dissipative structures that propagate at velocities approaching the\nspeed of sound. Crack initiation and subsequent propagation -- the dynamic\nprocess of fracture -- couples a wide range of time and length scales. Crack\ndynamics challenge our understanding of the fundamental physics processes that\ntake place in the extreme conditions within the nearly singular region where\nmaterial failure occurs. Here, we first briefly review the classic approach to\ndynamic fracture, \"Linear Elastic Fracture Mechanics\" (LEFM), and discuss its\nsuccesses and limitations. We show how, on the one hand, recent experiments\nperformed on straight cracks propagating in soft brittle materials have\nquantitatively confirmed the predictions of this theory to an unprecedented\ndegree. On the other hand, these experiments show how LEFM breaks down as the\nsingular region at the tip of a crack is approached. This breakdown naturally\nleads to a new theoretical framework coined \"Weakly Nonlinear Fracture\nMechanics\", where weak elastic nonlinearities are incorporated. The stronger\nsingularity predicted by this theory gives rise to a new and intrinsic length\nscale, $\\ell_{nl}$. These predictions are verified in detail through direct\nmeasurements. We then theoretically and experimentally review how the emergence\nof $\\ell_{nl}$ is linked to a new equation for crack motion, which predicts the\nexistence of a high-speed oscillatory crack instability whose wave-length is\ndetermined by $\\ell_{nl}$. We conclude by delineating outstanding challenges in\nthe field."
    },
    {
        "anchor": "Strong Phonon Anharmonicity of Clathrate Compound at High Temperature: Effects of strong phonon anharmonicity of a type-I clathrate Ba$_{\\rm\n8}$Ga$_{\\rm 16}$Sn$_{\\rm 30}$ induced by quadruple-well potential of guest\natoms were investigated. Phonon transport including coherent interbranch\ncomponent was analyzed using a first-principles-based self-consistent phonon\n(SCP) theory that gives temperature-dependent harmonic interatomic force\nconstants and by solving off-diagonal components of group velocity operator.\nExperimentally observed thermal conductivities have been reasonably reproduced\nby considering both lattice and electron contributions. Through the analysis\nwith the SCP theory, we found that hardening of guest modes leads to an\nincrease in lattice thermal conductivity at frequencies below those of\nframework-dominant flat modes (< 40 cm$^{\\rm -1}$), which finally results in\nthe slow decay and slight increase in the total lattice thermal conductivity\nwith increasing temperature. Detailed analyses revealed that the increase in\nlattice thermal conductivity at low frequency is attributed to (a) the increase\nin group velocities of phonon modes located at frequencies below that of the\nflat guest modes and (b) abnormal increase in lifetimes of phonon modes located\nbetween frequencies of the flat guest and framework modes with increasing\ntemperature. From an engineering point of view, this effect may lead to an\nintriguing phenomenon, a larger decrease in thermal conductivity due to\nnanostructuring at higher temperatures.",
        "positive": "Tunneling magneto thermo power in magnetic tunnel junction nanopillars: We study the tunneling magneto thermo power (TMTP) in CoFeB/MgO/CoFeB\nmagnetic tunnel junction nanopillars. Thermal gradients across the junctions\nare generated by a micropatterned electric heater line. Thermo power voltages\nup to a few tens of \\muV between the top and bottom contact of the nanopillars\nare measured which scale linearly with the applied heating power and hence with\nthe applied temperature gradient. The thermo power signal varies by up to 10\n\\muV upon reversal of the relative magnetic configuration of the two CoFeB\nlayers from parallel to antiparallel. This signal change corresponds to a large\nspin-dependent Seebeck coefficient of the order of 100 \\muV/K and a large TMTP\nchange of the tunnel junction of up to 90%."
    },
    {
        "anchor": "Correlation between stick-slip frictional sliding and charge transfer: A decade ago, Budakian and Putterman (Phys. Rev. Lett., {\\bf 85}, 1000\n(2000)) ascribed friction to the formation of bonds arising from contact\ncharging when a gold tip of a surface force apparatus was dragged on\npolymethylmethacrylate surface. We propose a stick-slip model that captures the\nobserved correlation between stick-slip events and charge transfer, and the\nlack of dependence of the scale factor connecting the force jumps and charge\ntransfer on normal load. Here, stick-slip dynamics arises as a competition\nbetween the visco-elastic and plastic deformation time scales and that due to\nthe pull speed with contact charging playing a minor role. Our model provides\nan alternate basis for explaining most experimental results without ascribing\nfriction to contact charging.",
        "positive": "Magnetic memory effect in ensembles of interacting anisotropic magnetic\n  nanoparticles: We explore the influence of demagnetization interaction on magnetic memory\neffect by varying organization geometry of anisotropic ZnFe$_2$O$_4$\nnanoparticles in an ensemble. The static and dynamic behaviour of two\ndifferently organized ensembles, compact ensemble (CE) and hollow core ensemble\n(HCE), are extensively studied by both dc and ac susceptibility, magnetic\nmemory effect and spin relaxation. The frequency-dependence peak shifting of\nfreezing temperature in both the systems is analyzed properly with the help of\ntwo dynamic scaling models: Vogel-Fulcher law and power law. Presence of\ncluster spin-glass phase is reflected from Vogel-Fulcher temperature $T_0$\n$\\simeq$ 142.58 K for CE, $\\simeq$ 97 K for HCE and characteristic time\nconstant $\\tau_0$ $\\simeq$ $8.85\\times10^{-9}$ s for CE, $\\simeq$\n$3.8\\times10^{-10}$ s for HCE; along with $\\delta$T$_{Th}$ $\\sim$ 0.1 for CE\nand 0.2 for HCE. The power law fitting with dynamic exponent $zv'$ = 6.2 $\\pm$\n1.1 for CE, 6.3 $\\pm$ 0.5 for HCE and single spin flip $\\tau^*$ $\\simeq$\n$7.7\\times10^{-11}$ s for CE, $\\simeq$ $1.3\\times10^{-10}$ s for HCE provide\nfirm confirmation of cluster spin-glass phase. The progressive spin freezing\nacross multiple metastable states with prominent memory effects is reflected in\nboth the systems via nonequilibrium dynamics study. The hollow core geometry\nwith anisotropic nanoparticles on surface with closer proximity leads to\ncomplex anisotropy energy landscape with enhanced demagnetizing field resulting\nhighly frustrated surface spins. As a consequence, more prominent magnetic\nmemory effect is observed in HCE with higher activation energy, reduced\nblocking temperature and enhanced coercivity than that of CE."
    },
    {
        "anchor": "Doping-induced dielectric catastrophe prompts free-carrier release in\n  organic semiconductors: The control over material properties attainable through molecular doping is\nessential to many technological applications of organic semiconductors, such as\nOLED or thermoelectrics. These excitonic semiconductors typically reach the\ndegenerate limit only at impurity concentrations of 5-10\\%, a phenomenon that\nhas been put in relation to the strong Coulomb binding between charge carriers\nand ionized dopants, and whose comprehension remained elusive so far. This\nstudy proposes a general mechanism for the release of carriers at finite doping\nin terms of collective screening phenomena. A multiscale model for the\ndielectric properties of doped organic semiconductor is set up by combining\nfirst principles and microelectrostatic calculations. Our results predict a\nlarge nonlinear enhancement of the dielectric constant (ten-fold at 8\\% load)\nas the system approaches a dielectric instability (catastrophe) upon increasing\ndoping. This can be attributed to the presence of highly polarizable\nhost-dopant complexes, plus a nontrivial leading contribution from dipolar\ninteractions in the disordered and heterogeneous system. The enhanced screening\nin the material drastically reduces the (free) energy barriers for\nelectron-hole separation, rationalizing the possibility for thermal charge\nrelease. The proposed mechanism is consistent with conductivity data and sets\nthe basis for achieving higher conductivities at lower doping loads.",
        "positive": "Anharmonicity-driven Rashba co-helical excitons break quantum efficiency\n  limitation: Closed-shell light-emitting diodes (LEDs) suffer from the internal quantum\nefficiency (IQE) limitation imposed by optically inactive triplet excitons.\nHere we show an undiscovered emission mechanism of lead-halide-perovskites\n(LHPs) APbX$_3$ (A=Cs/CN$_2$H$_5$; X=Cl/Br/I) that circumvents the efficiency\nlimit of closed-shell LEDs. Though efficient emission is prohibited by\noptically inactive $J=0$ in inversion symmetric LHPs, the anharmonicity arising\nfrom stereochemistry of Pb and resonant orbital-bonding network along the\nimaginary A$^+\\cdots$X$^-$ (T$_{1u}$) transverse optical (TO) modes, breaks the\ninversion symmetry and introduces disorder and Rashba-Dresselhaus spin-orbit\ncoupling (RD-SOC). This leads to bright co-helical and dark anti-helical\nexcitons. Many-body theory and first-principles calculations affirm that the\noptically active co-helical exciton is the lowest excited state in\norganic/inorganic LHPs. Thus, RD-SOC can drive to achieve the ideal 50 $\\%$ IQE\nby utilizing anharmonicity, much over the 25 $\\%$ IQE limitation for\nclosed-shell LEDs."
    },
    {
        "anchor": "Ab initio study of the structure and properties of amorphous silicon\n  hydride from accelerated molecular dynamics simulations: This paper presents a large-scale $ab$ $initio$ simulation study of amorphous\nsilicon hydride ($a$-Si$_{\\text{1-x}}$H$_{\\text{x}}$) with an emphasis on the\nstructure and properties of the material across a range of hydrogen\nconcentration by combining accelerated molecular dynamics (MD) simulations with\nfirst-principles density-functional calculations. The accelerated MD scheme\nrelied on classical metadynamics, which enabled the development of 2600+\nhigh-quality structural models of $a$-Si$_{\\text{1-x}}$H$_{\\text{x}}$, with\nsystem sizes ranging from 150 to 6,000 atoms and hydrogen concentrations vary\nfrom 6 to 20 at. %H. The resulting amorphous networks were found to be\ncompletely free from any coordination defects and that they all exhibited a\npristine band-gap in their electronic spectrum. The microstructural properties\nof hydrogen distributions were examined with great emphasis on the presence of\nisolated and clustered environments of hydrogen atoms. The results were\ncompared with a suite of experimental data obtained from x-ray diffraction,\ninfrared spectroscopy, spectroscopic ellipsometry and nuclear magnetic\nresonance studies.",
        "positive": "From Node-Line Semimetals to Large Gap QSH States in New Family of\n  Pentagonal Group-IVA Chalcogenide: Two-dimensional (2D) topological insulators (TIs) have attracted tremendous\nresearch interest from both theoretical and experimental fields in recent\nyears. However, it is much less investigated in realizing node line (NL)\nsemimetals in 2D materials.Combining first-principles calculations and $k \\cdot\np$ model, we find that NL phases emerge in p-CS$_2$ and p-SiS$_2$, as well as\nother pentagonal IVX$_2$ films, i.e. p-IVX$_2$ (IV= C, Si, Ge, Sn, Pb; X=S, Se,\nTe) in the absence of spin-orbital coupling (SOC). The NLs in p-IVX$_2$ form\nsymbolic Fermi loops centered around the $\\Gamma$ point and are protected by\nmirror reflection symmetry. As the atomic number is downward shifted, the NL\nsemimetals are driven into 2D TIs with the large bulk gap up to 0.715 eV\ninduced by the remarkable SOC effect.The nontrivial bulk gap can be tunable\nunder external biaxial and uniaxial strain. Moreover, we also propose a quantum\nwell by sandwiching p-PbTe$_2$ crystal between two NaI sheets, in which\np-PbTe$_2$ still keeps its nontrivial topology with a sizable band gap ($\\sim$\n0.5 eV). These findings provide a new 2D materials family for future design and\nfabrication of NL semimetals and TIs."
    },
    {
        "anchor": "Hybrid-functional and quasi-particle calculations of band structures of\n  Mg2Si, Mg2Ge, and Mg2Sn: We perform hybrid functional and quasi-particle band structure calculations\nwith spin-orbit interaction to investigate the band structures of Mg2Si, Mg2Ge,\nand Mg2Sn. For all Mg2X materials, where X = Si, Ge, and Sn, the\ncharacteristics of band edge states, i.e., band and valley degeneracies, and\norbital characters, are found to be conserved, independent of the computational\nschemes such as density functional generalized gradient approximation, hybrid\nfunctionals, or quasi-particle calculations. However, the magnitude of the\ncalculated band gap varies significantly with the computational schemes. Within\ndensity-functional calculations, the one-particle band gaps of Mg2Si, Mg2Ge,\nand Mg2Sn are 0.191, 0.090, and -0.346 eV, respectively, and thus severely\nunderestimated compared to the experimental gaps, due to the band gap error in\nthe density functional theory and the significant relativistic effect on the\nlow-energy band structures. By employing hybrid-functional calculations with a\n35% fraction of the exact Hartree-Fock exchange energy (HSE-35%), we overcame\nthe negative band gap issue in Mg2Sn. Finally, in quasi-particle calculations\non top of the HSE-35% Hamiltonians, we obtained band gaps of 0.835, 0.759, and\n0.244 eV for Mg2Si, Mg2Ge, and Mg2Sn, respectively, consistent with the\nexperimental band gaps of 0.77, 0.74, and 0.36 eV, respectively.",
        "positive": "Defect processes in Be$_{12}$X Beryllides: The stability of intrinsic point defects in Be$_{12}$X intermetallics (where\nX = Ti, V, Mo or W) are predicted using density functional theory simulations\nand discussed with respect to fusion energy applications. Schottky disorder is\nfound to be the lowest energy complete disorder process, closely matched by Be\nFrenkel disorder in the cases of Be$_{12}$V and Be$_{12}$Ti. Antitisite and X\nFrenkel disorder are of significantly higher energy. Small clusters of point\ndefects including Be divacancies, Be di-interstitials and accommodation of the\nX species on two Be sites were considered. Some di-interstitial, divacancy and\nX$_{2Be}$ combinations exhibit negative binding enthalpy (i.e. clustering is\nfavourable), although this is orientationally dependent. None of the Be$_{12}$X\nintermetallics are predicted to exhibit significant non-stoichiometry, ruling\nout non-stoichiometry as a mechanism for accommodating Be depletion due to\nneutron transmutation."
    },
    {
        "anchor": "Magnetic resonance study of bulk and thin film EuTiO3: Magnetic resonance spectra of EuTiO3 in both bulk and thin film form were\ntaken at temperatures from 3-350 K and microwave frequencies from 9.2-9.8 and\n34 GHz. In the paramagnetic phase, magnetic resonance spectra are determined by\nmagnetic dipole and exchange interactions between Eu2+ spins. In the film, a\nlarge contribution arises from the demagnetization field. From detailed\nanalysis of the linewidth and its temperature dependence, the parameters of\nspin-spin interactions were determined: the exchange frequency is 15-15.5 GHz\nand the estimated critical exponent of the spin correlation length is ~ 0.5. In\nthe bulk samples, the spectra exhibited a distinct minimum in the linewidth at\nthe N\\'eel temperature, T_N = 5.5 K, while the resonance field practically does\nnot change even on cooling below T_N. This is indicative of a small magnetic\nanisotropy ~ 320 G in the antiferromagnetic phase. In the film, the magnetic\nresonance spectrum is split below T_N into several components due to excitation\nof the magnetostatic modes, corresponding to a non-uniform precession of\nmagnetization. Moreover, the film was observed to degrade over two years. This\nwas manifested by an increase of defects and a change in the domain structure.\nThe saturated magnetization in the film, estimated from the magnetic resonance\nspectrum, was about 900 emu/cm3 or 5.5 mu_B/unit cell at T = 3.5 K.",
        "positive": "Internal stresses analysis on welded joint in Grade 91 steel under creep\n  test: synchrotron DRX tests and modelling: The analysis and understanding of creep damage of Grade 91 steel welded\njoints is an important topic in the energy industry. Creep tests on welded\njoints were carried out at 600$^{\\circ}$C, 100MPa and then interrupted at 0%,\n10%, 30%, 50%, 80% of the expected life and after failure. Creep damage is\ncharacterised by cavity bands located exclusively in the core of the sample in\nthe InterCritical Heat Affected Zone (ICHAZ). These samples were tested using\n\\textit{in situ} synchrotron XRD along the welded joint under creep conditions\nfor the different creep life time. The experimental results show a significant\nstrain evolution and creep damage characteristic on the welded joint, with a\nlocal maximum at the Heat Affected Zone (HAZ). Following this, a finite element\ncreep strain analysis was performed for comparison with the experimental\nresults."
    },
    {
        "anchor": "Radical Anion Functionalization of Two-Dimensional Materials as a Means\n  of Engineering Simultaneously High Electronic and Ionic Conductivity Solids: A radical anion based functionalization of the basal plane of two-dimensional\n(2D) materials is proposed in the present study. Simple charge neutral radical\nfunctionalizations typically detach from the basal planes upon reduction. For\nexample, epoxy oxygens irreversibly detach from graphene when reduced by an\nalkali metal. The radical anion functionalization of 2D materials results in a\nstable reduced state that can reversibly be oxidized and has high ionic\nconductivity due to the great mobility of the cations between the negatively\ncharged functional groups on the surface. Depending on the oxidation state of\nthese systems, a high concentration of hole states can also be realized\nallowing for good electronic conductivity. These properties can further allow\nfor improved energy storage devices via transition metal free cathode active\nspecies, solid electrolytes, electroconductive additives, separators, coatings\nfor metal anodes and heat conductors through a single material. One possible\nrealization of the above principles is the 2D salt An(BN)2OBX3, where A is an\nalkali atom (Li, Na, etc; 0=<n=<2) or alkaline earth (Mg, etc; 0=<n=<1) and X\nis a halide (typically F or Cl). This material can be derived from the basal\nplane functionalization of hexagonal boron nitride, h-BN, with .OBX3^- radical\nanions in the presence of the A cations. One potential source of .OBX3^-\nradical anions is their recombined form, the [X3B-O-O-BX3]2- anion, which can\nbe found in the Lewis adduct of an AnO2 ionic peroxide with BX3:\nAn[X3B-O-O-BX3]. The individual radical anions can be obtained by thermally\nsplitting the O-O bond in the recombined anion. Transition metal free\nall-solid-state batteries with Li, Na and Mg anodes, thermal stability and high\nenergy and power densities may be realizable using An(BN)2OBX3.",
        "positive": "Topological Semimetal features in the Multiferroic Hexagonal Manganites: Using first-principles calculations we examine the band structures of\nferromagnetic hexagonal manganites $\\mathrm{YXO_3}$ (X=V, Cr, Mn, Fe and Co) in\nthe nonpolar nonsymmorphic $P6_3/mmc$ space group. For $\\mathrm{YVO_3}$ and\n$\\mathrm{YCrO_3}$ we find a band inversion near the Fermi energy that generates\na nodal ring in the $k_z=0$ mirror plane. We perform a more detailed analysis\nfor these compounds and predict the existence of the topological \"drumhead\"\nsurface states. Finally, we briefly discuss the low-symmetry polar phases\n(space group $P6_3cm$) of these systems, and show they can undergo a $P6_3/mmc\n\\rightarrow P6_3cm$ transition by condensation of soft $K_3$ and $\\Gamma_2^-$\nphonons. Based on our findings, stabilizing these compounds in the hexagonal\nphase could offer a promising platform for studying the interplay of topology\nand multiferroicity, and the coexistence of real-space and reciprocal-space\ntopological protection in the same phase."
    },
    {
        "anchor": "Loss of control in pattern-directed nucleation: a theoretical study: The properties of template-directed nucleation are studied close to the\ntransition where full nucleation control is lost and additional nucleation\noccurs beyond the pre-patterned regions. First, kinetic Monte Carlo simulations\nare performed to obtain information on a microscopic level. Here the\nexperimentally relevant cases of 1D stripe patterns and 2D square lattice\nsymmetry are considered. The nucleation properties in the transition region\ndepend in a complex way on the parameters of the system, i.e. the flux, the\nsurface diffusion constant, the geometric properties of the pattern and the\ndesorption rate. Second, the properties of the stationary concentration field\nin the fully controlled case are studied to derive the remaining nucleation\nprobability and thus to characterize the loss of nucleation control. Using the\nanalytically accessible solution of a model system with purely radial symmetry,\nsome of the observed properties can be rationalized. A detailed comparison to\nthe Monte Carlo data is included.",
        "positive": "Structural, electronic and bonding properties of zeolite Sn-Beta: A\n  periodic density functional theory study: The structural, electronic and the bonding properties of the Sn-BEA are\ninvestigated by using the periodic density functional theory. Each of the 9\ndifferent T-sites in the BEA were substituted by the Sn atom and all the 9\ngeometries were completely optimized using the plane wave basis set in\nconjunction with the ultra-soft pseudopotential. On the basis of the structural\nand the electronic properties, it has been demonstrated that the substitution\nof the Sn atom in the BEA framework is an endothermic process and hence the\nincorporation of the Sn in the BEA is limited. The lowest unoccupied molecular\norbitals (LUMO) energies have been used to characterize the Lewis acidity of\neach T-site. On the basis of the relative cohesive energy and the LUMO energy,\nT2 site is shown to be the most favorable site for the substitution of Sn atom\nin the BEA framework."
    },
    {
        "anchor": "Reentrant phase in nanoferroics induced by the flexoelectric and Vegard\n  effects: We explore the impact of the flexoelectric effect and Vegard effect (chemical\npressure) on the phase diagrams, long-range polar order and related physical\nproperties of the spherical ferroelectric nanoparticles using\nLandau-Ginzburg-Devonshire phenomenological approach. The synergy of these\neffects can lead to the remarkable changes of the nanoparticles' phase\ndiagrams. In particular, a commonly expected transition from ferroelectric to\nparaelectric phase at some small critical size is absent; so that the critical\nsize loses its sense. Contrary, the stabilization of the ferroelectric phase\nmanifests itself by the enhancement of the transition temperature and\npolarization with the particle size decrease. Ferroelectric phase reentrant\nphenomenon was observed earlier in the tetragonal BaTiO3 nanospheres of radii\n5-50 nm [Zhu et al., JAP 112, 064110 (2012)] and stayed unexplained up to now.\nOur calculations have shown the physical mechanism of the exciting phenomenon\nis the flexo-chemo-effect. Since the spontaneous flexoelectric coupling, as\nwell as ion vacancies, should exist in any nanostructured ferroelectrics,\nobtained analytical results can be valid for many nanoferroelectrics, where\nreentrant phases appearance can be forecasted.",
        "positive": "A robust weak topological insulator in a bismuth halide Bi4Br2I2: We apply a topological material design concept for selecting a bulk topology\nof 3D crystals by different van-der-Waals stacking of 2D topological insulator\nlayers, and find a bismuth halide Bi4Br2I2 to be an ideal weak topological\ninsulator (WTI) with the largest band gap (~230 meV) among all the WTI\ncandidates, by means of angle-resolved photoemission spectroscopy (ARPES),\ndensity functional theory (DFT) calculations, and resistivity measurements. Our\nresults vastly expand future opportunities for fundamental research and device\napplications with a robust WTI."
    },
    {
        "anchor": "Anisotropic electron mobility studies on Cl2-NDI single crystals and the\n  role of static and dynamic lattice deformations upon temperature variation: The anisotropic electron transport in the (001) plane of sublimation-grown\nCl$_{2}$-NDI (naphthalene diimide) single crystals is analysed over a\ntemperature range between 175 K and 300 K. Upon cooling from room temperature\nto 175 K the electron mobility along the direction of preferred transport\nmonotonously increases from 1.5 cm$^{2}$/Vs to 2.8 cm$^{2}$/Vs according to a\ndistinct temperature relation of $~T^{-1.3}$. At first glance, these\ncharacteristics allude to a coherent, i.e. band-like charge carrier transport\npredominantly governed by inelastic scattering with accoustic phonons. However,\nas we will demonstrate, the experimental mobility data can be consistently\ndescribed within the framework of incoherent, hopping-type transport modeled by\nLevich-Jortner rates, explicitly accounting for the inner and outer relaxation\nenergies related to thermally induced lattice effects and enhanced\nelectron-phonon interaction at elevated temperatures. Complementary\nband-structure calculations yielding temperature dependent effective mass\ntensors deviate stronger from experimentally observed spatially anisotropic\ntransport behavior. Thus, these results hint at the fact that by the particular\ninterplay of the transport energies the mobility of a given organic\nsemiconducting material might appear to be band-like in a certain temperature\nregime even though the underlying charge carrier transport can be of\nincoherent, hopping-type nature. Building on this description, we further\nexplore the role of the intermolecular electronic coupling and develop a\nprocedure to distinguish between its dependence on static and dynamic lattice\ndeformation upon temperature variation.",
        "positive": "Stereochemically Active Lone-pair Leads to Strong Birefringence in the\n  Vacancy Ordered Cs3Sb2Cl9 Perovskite Single Crystals: Stereochemically active lone-pair (SCALP) cations are attractive units for\nrealizing optical anisotropy. Antimony (III) chloride perovskites with SCALP\nhave remained largely unknown till date. We synthesized vacancy ordered\nCs3Sb2Cl9 perovskite single crystals with SbCl6 octahedral linkage containing\nSCALP. Remarkably, Cs3Sb2Cl9 single crystals exhibit an exceptional\nbirefringence of 0.12 +(-) 0.01 at 550 nm, which is the largest among pristine\nall-inorganic halide perovskites. The SCALP brings a large local structural\ndistortion of the SbCl6 octahedra promoting birefringence optical responses in\nCs3Sb2Cl9 single crystals. Theoretical calculations reveal that the\nconsiderable hybridization of Sb 5s with Sb 5p and Cl 3p states largely\ncontribute to the SCALP. Furthermore, the change in the Sb-Cl-Sb bond angle\ncreates distortion in the SbCl6 octahedral arrangement in the apical and\nequatorial directions within the crystal structure incorporating the required\nanisotropy for the birefringence. This work explores pristine inorganic halide\nperovskite single crystals as a potential birefringent material with prospects\nin integrated optical devices."
    },
    {
        "anchor": "Native point defects and low $p$-doping efficiency in $Mg_2 (Si,Sn)$\n  solid solutions: A hybrid-density functional study: We perform hybrid-density functional calculations to investigate the charged\ndefect formation energy of native point defects in $Mg_2 Si$, $Mg_2 Sn$, and\ntheir solid solutions. The band gap correction by hybrid-density functional is\nfound to be critical to determine the charged defect density in these\nmaterials. For $Mg_2 Si$, $Mg$ interstitials are dominant and provide\nunintentional $n$-type conductivity. Additionally, as the $Mg$ vacancies can\ndominate in $Mg$-poor $Mg_2 Sn$, $p$-type conductivity is possible for $Mg_2\nSn$. However, the existence of low formation energy defects such as\n$Mg_{Sn}^{1+}$ and $I_{Mg}^{2+}$ in $Mg_2 Sn$ and their diffusion can cause\nsevere charge compensation of hole carriers resulting in low $p$-type doping\nefficiency and thermal degradation. Our results indicate that, in addition to\nthe extrinsic doping strategy, alloying of $Mg_2 Si$ with $Mg_2 Sn$ under\n$Mg$-poor conditions would be necessary to enhance the $p$-type conductivity\nwith less charge compensation.",
        "positive": "Crystallographic evaluation of low cycle fatigue crack growth in a\n  polycrystalline Ni based superalloy: The present work discusses the micro-mechanism of low cycle fatigue (LCF)\ncrack growth in smooth bar specimens of Haynes 282. Two parametric approaches,\ni.e. crack tip opening angle (CTOA) and maximum tangential stress ({\\theta}MTS)\nhave been opted to characterize the cracks. CTOA variations along with a\npropagating crack, exhibit a non-linear decay followed by a stabilized regime.\nMixicity of local KI and KII fields is directly proportional to {\\theta}MTS and\nthat can be assessed by measuring local deflections. Around the crack, the role\nof grain incompatibility has been addressed through EBSD and slip transfer\nanalysis. There is a critical bound for Elastic Modulus (EM) and Schmid factor\n(SF) for the grains favouring subsurface crack propagation, and these values\nexist beyond a limiting threshold. The SF-EM maps mark the regions of cracked\nand uncracked grains in the material. The favourable twin-matrix\nincompatibility of the microstructure has also been identified about the\nfatigue crack growth and twins in (211) plane is abundant in the cracked\nregion. A detailed slip transfer analysis based on the Luster-Morris parameter\n(LMP) has been carried out for investigating the interrelation between slip\nactivity, elasto-plastic incompatibility, and grain boundary geometry."
    },
    {
        "anchor": "Large crystal local-field effects in the dynamical structure factor of\n  rutile TiO2: We present ab initio time-dependent-density-functional calculations and\nnon-resonant inelastic x-ray scattering measurements of the dynamical structure\nfactor of rutile TiO2. Our calculations are in good agreement with experiment\nand prove the presence of large crystal local-field effects below the Ti\nM-edge, which yield a sharp loss peak at 14 eV whose intensity features a\nremarkable non-monotonic dependence on the wave vector. These effects, which\nimpact the excitation spectra in the oxide more dramatically than in transition\nmetals, provide a signature of the underlying electronic structure.",
        "positive": "Magnetic monolayer Li$_{2}$N: Density Functional Theory Calculations: Density functional theory (DFT) calculations are used to investigate the\nelectronic and magnetic structures of a two-dimensional (2D) monolayer\nLi$_{2}$N. It is shown that bulk Li$_{3}$N is a non-magnetic semiconductor. The\nnon-spinpolarized DFT calculations show that $p$ electrons of N in 2D Li$_{2}$N\nform a narrow band at the Fermi energy $E_{\\rm{F}}$ due to a low coordination\nnumber, and the density of states at the Fermi energy ($g(E_{\\rm{F}}$)) is\nincreased as compared with bulk Li$_{3}$N. The large $g(E_{\\rm{F}}$) shows\ninstability towards magnetism in Stoner's mean field model. The spin-polarized\ncalculations reveal that 2D Li$_{2}$N is magnetic without intrinsic or impurity\ndefects. The magnetic moment of 1.0\\,$\\mu_{\\rm{B}}$ in 2D Li$_{2}$N is mainly\ncontributed by the $p_{z}$ electrons of N, and the band structure shows\nhalf-metallic behavior. {Dynamic instability in planar Li$_{2}$N monolayer is\nobserved, but a buckled Li$_{2}$N monolayer is found to be dynamically stable.}\nThe ferromagnetic (FM) and antiferromagnetic (AFM) coupling between the N atoms\nis also investigated to access the exchange field strength. {We found that\nplanar (buckled) 2D Li$_{2}$N is a ferromagnetic material with Curie\ntemperature $T_{c}$ of 161 (572) K.}"
    },
    {
        "anchor": "Origin of charge density at LaAlO3-on-SrTiO3 hetero-interfaces;\n  possibility of intrinsic doping: As discovered by Ohtomo et al., a large sheet charge density with high\nmobility exists at the interface between SrTiO3 and LaAlO3. Based on transport,\nspectroscopic and oxygen-annealing experiments, we conclude that extrinsic\ndefects in the form of oxygen vacancies introduced by the pulsed laser\ndeposition process used by all researchers to date to make these samples is the\nsource of the large carrier densities. Annealing experiments show a limiting\ncarrier density. We also present a model that explains the high mobility based\non carrier redistribution due to an increased dielectric constant.",
        "positive": "Development of an Ion-Sensor using Fluorescence Resonance Energy\n  Transfer: A method is presented for the sensing of ions by determining the\nconcentration of corresponding salts (KCl, NaCl, MgCl2, CaCl2, FeCl3, FeSO4,\nAlCl3) in water, based on Fluorescence resonance energy transfer (FRET)\nprocess. The principle of the proposed sensor is based on the change of FRET\nefficiency between two laser dyes Acriflavine and Rhodamine B in presence of\ndifferent ions (K+, Na+, Mg2+, Ca2+, Fe2+, Fe3+, Al3+). Nanodimensional clay\nplatelet laponite was used to enhance the efficiency of the sensor."
    },
    {
        "anchor": "Enhanced and continuous electrostatic carrier doping on the SrTiO$_{3}$\n  surface: Paraelectrical tuning of a charge carrier density as high as\n10$^{13}$\\,cm$^{-2}$ in the presence of a high electronic carrier mobility on\nthe delicate surfaces of correlated oxides, is a key to the technological\nbreakthrough of a field effect transistor (FET) utilising the metal-nonmetal\ntransition. Here we introduce the Parylene-C/Ta$_{2}$O$_{5}$ hybrid gate\ninsulator and fabricate FET devices on single-crystalline SrTiO$_{3}$, which\nhas been regarded as a bedrock material for oxide electronics. The gate\ninsulator accumulates up to $\\sim10^{13}$cm$^{-2}$ carriers, while the\nfield-effect mobility is kept at 10\\,cm$^2$/Vs even at room temperature.\nFurther to the exceptional performance of our devices, the enhanced\ncompatibility of high carrier density and high mobility revealed the mechanism\nfor the long standing puzzle of the distribution of electrostatically doped\ncarriers on the surface of SrTiO$_{3}$. Namely, the formation and continuous\nevolution of field domains and current filaments.",
        "positive": "Intergranular normal stress distributions in untextured polycrystalline\n  aggregates: From a general point of view, InterGranular Stress-Corrosion Cracking (IGSCC)\nresults from the interplay between mechanical loading and grain boundaries\nopening. The former leads to intergranular stresses in polycrystalline\naggregates, the latter being either stress-accelerated or stress-induced. This\nwork aims at obtaining intergranular normal stress distributions in uncracked\npolycrystalline aggregates, which is considered as a key milestone towards\nIGSCC initiation predictive modelling. Based on the finite element method,\nnumerical simulations have been performed on Voronoi polycrystalline aggregates\nconsidering a wide variety of material constitutive equations: crystal\nelasticity (cubic and hexagonal symmetries) with different anisotropy ratios\nand crystal plasticity for different sets of slip systems under the assumption\nof uniform critical resolved shear stress: Face-Centered Cubic (FCC),\nBody-Centered Cubic (BCC) and Hexagonal Close Packed (HCP) with or without\nhardening, and for both uniaxial and equibiaxial macroscopic loading\nconditions. In the elastic regime, a correlation between standard deviations of\nintergranular normal stress distributions and a universal elastic anisotropy\nindex proposed recently is found and explained through a simple model. For\nmacroscopic strain larger than the yield strain, the evolution of standard\ndeviations with strain is rationalized by accounting only for the macroscopic\nelastic strain and the standard deviation of Taylor factor. These numerical\nresults associated with physically-based simple models allow to estimate easily\nintergranular normal stress concentrations, constituting a tool for classifying\npolycrystalline aggregates according to their potential susceptibility to\nIGSCC."
    },
    {
        "anchor": "A novel dielectric elastomer actuator based on polyvinyl alcohol\n  hydrogel electrodes: We firstly demonstrate physically-prepared compliant PVA hydrogel electrodes\nas a promising supplement in dielectric elastomer actuators. They are capable\nof conducting high voltages over 5 kV without electrolysis by an electrical\ndouble layer effect. The hydrogel electrodes adhere tightly to the dielectric\nlayer, which ensures its structural stability during actuation. All-polymeric\nactuators fabricated by these electrodes exhibited excellent consecutive\nworking performance over 2960 cycles. The actuation was influenced by applied\nvoltage, ramp rate, electrode elastic modulus and moisture content. A maximum\nareal strain over 78% was achieved. Tunable transparency, good\nbiocompatibility, long lifetime, low cost and facile fabrication make PVA\nhydrogel electrode another promising candidate in the fields of sensors,\nartificial muscles and optical applications.",
        "positive": "Two-dimensional Weyl points and nodal lines in pentagonal materials and\n  their optical response: Two-dimensional pentagonal structures based on the Cairo tiling are the basis\nof a family of layered materials with appealing physical properties. In this\nwork we present a theoretical study of the symmetry-based electronic and\noptical properties of these pentagonal materials. We provide a complete\nclassification of the space groups that support pentagonal structures for\nbinary and ternary systems. By means of first-principles calculations, their\nelectronic band structures and the local spin textures in momentum space are\nanalyzed. Our results show that pentagonal structures can be realized in chiral\nand achiral lattices with Weyl nodes pinned at high-symmetry points and nodal\nlines along the Brillouin zone boundary; these degeneracies are protected by\nthe combined action of crystalline and time-reversal symmetries. Additionally,\nwe discuss the linear and nonlinear optical features of some penta-materials,\nsuch as the shift current, which shows an enhancement due to the presence of\nnodal lines and points, and their possible applications."
    },
    {
        "anchor": "Mechanisms for collective inversion-symmetry breaking in dabconium\n  perovskite ferroelectrics: Dabconium hybrid perovskites include a number of recently-discovered\nferroelectric phases with large spontaneous polarisations. The origin of\nferroelectric response has been rationalised in general terms in the context of\nhydrogen bonding, covalency, and strain coupling. Here we use a combination of\nsimple theory, Monte Carlo simulations, and density functional theory\ncalculations to assess the ability of these microscopic ingredients---together\nwith the always-present through-space dipolar coupling---to account for the\nemergence of polarisation in these particular systems whilst not in other\nhybrid perovskites. Our key result is that the combination of A-site polarity,\npreferred orientation along $\\langle111\\rangle$ directions, and ferroelastic\nstrain coupling drives precisely the ferroelectric transition observed\nexperimentally. We rationalise the absence of polarisation in many hybrid\nperovskites, and arrive at a set of design rules for generating FE examples\nbeyond the dabconium family alone.",
        "positive": "Charging of Cu atom on Mo supported thin films of ScN, MgO and NaF: Molybdenum supported thin films of ScN, MgO and NaF with a Cu adatom have\nbeen studied in the framework of density functional theory. We have observed a\ncharge transfer from the metal/film interface to the Cu atom and investigated\nits relation to surface and interface deformations. We find that a weak\ninteraction between the metal and the film is a promising prerequisite for\nadatom charging. The detailed study of Cu/NaF/Mo and NaF/Mo indicates that the\ndistortion of the NaF film caused by the Cu adsorption has essentially\nanharmonic character, as it is coupled to a strong charge redistribution in the\nsystem."
    },
    {
        "anchor": "High-temperature ferromagnetism and strong $\u03c0$-conjugation feature in\n  two-dimensional manganese tetranitride: Two-dimensional (2D) magnetic materials have attracted tremendous research\ninterest because of the promising application in the next-generation\nmicroelectronic devices. Here, by the first-principles calculations, we propose\na two-dimensional ferromagnetic material with high Curie temperature, manganese\ntetranitride MnN$_4$ monolayer, which is a square-planar lattice made up of\nonly one layer of atoms. The structure is demonstrated to be stable by the\nphonon spectra and the molecular dynamic simulations, and the stability is\nascribed to the $\\pi$-d conjugation between $\\pi$ orbital of N=N bond and Mn\n$d$ orbital. More interestingly, the MnN$_4$ monolayer displays robust 2D\nferromagnetism, which originates from the strong exchange couplings between Mn\natoms due to the $\\pi$-d conjugation. The high critical temperature of 247 K is\ndetermined by solving the Heisenberg model with the Monte Carlo method.",
        "positive": "Universal scaling of the electronic and the elastic energies of small\n  polarons revealed by high-throughput first-principles calculations: Formation of self-trapped holes (STH) in a comprehensive list of scintillator\nmaterials, including halides and chalcogenides, are studied using an accurate\nand computationally efficient first-principles method, the polaron\nself-interaction correction (pSIC). The key characteristics of small hole\npolarons, including their geometries, energies and degree of localization, are\nfound vastly different from halides to oxides to systems with open-shell\ncations. Nevertheless, we find a universal linear relation between the energy\ngap separating the bound hole level from the valence band maximum and the\nelastic energy associated with the lattice displacement field that accompanies\nthe polaron."
    },
    {
        "anchor": "Metallic nanolines ruled by grain boundaries in graphene: an ab initio\n  study: We have performed an ab initio investigation of the energetic stability, and\nthe electronic properties of transition metals (TMs = Mn, Fe, Co, and Ru)\nadsorbed on graphene upon the presence of grain boundaries (GBs). Our results\nreveal an energetic preference for the TMs lying along the GB sites (TM/GB).\nSuch an energetic preference has been strengthened by increasing the\nconcentration of the TM adatoms; giving rise to TM nanolines on graphene ruled\nby GBs. Further diffusion barrier calculations for Fe adatoms support the\nformation of those TM nanolines. We find that the energy barriers parallel to\nthe GBs are sligthly lower in comparision with those obtained for the defect\nfree graphene; whereas, perpendicularly to the GBs the Fe adatoms face higher\nenergy barriers. Fe and Co (Mn) nanolines are ferromagnetic (ferrimagnetic), in\ncontrast the magnetic state of Ru nanolines is sensitive to the Ru/GB\nadsorption geometry. The electronic properties of those TM nanolines were\ncharacterized through extensive electronic band structure calculations. The\nformation of metallic nanolines is mediated by a strong hybridization between\nthe TM and the graphene ($\\pi$) orbitals along the GB sites. Due to the net\nmagnetization of the TM nanolines, our band structure results indicate an\nanisotropic (spin-polarized) electronic current for some TM/GB systems.",
        "positive": "Stacking-dependent electronic property of trilayer graphene epitaxially\n  grown on Ru(0001): The growth, atomic structure, and electronic property of trilayer graphene\n(TLG) on Ru(0001) were studied by low temperature scanning tunneling microscopy\nand spectroscopy in combined with tight-binding approximation (TBA)\ncalculations. TLG on Ru(0001) shows a flat surface with a hexagonal lattice due\nto the screening effect of the bottom two layers and the AB-stacking in the top\ntwo layers. The coexistence of AA- and AB-stacking in the bottom two layers\nleads to three different stacking orders of TLG, namely, ABA-, ABC-, and\nABB-stacking. STS measurements combined with TBA calculations reveal that the\ndensity of states of TLG with ABC- and ABB-stacking is characterized by one and\ntwo sharp peaks near to the Fermi level, respectively, in contrast to the\nV-shaped feature of TLG with ABA-stacking. Our work demonstrates that TLG on\nRu(0001) might be an ideal platform for exploring stacking-dependent electronic\nproperties of graphene."
    },
    {
        "anchor": "Interface and electronic characterization of thin epitaxial Co3O4 films: The interface and electronic structure of thin (~20-74 nm) Co3O4(110)\nepitaxial films grown by oxygen-assisted molecular beam epitaxy on MgAl2O4(110)\nsingle crystal substrates have been investigated by means of real and\nreciprocal space techniques. As-grown film surfaces are found to be relatively\ndisordered and exhibit an oblique low energy electron diffraction (LEED)\npattern associated with the O-rich CoO2 bulk termination of the (110) surface.\nInterface and bulk film structure are found to improve significantly with\npost-growth annealing at 820 K in air and display sharp rectangular LEED\npatterns, suggesting a surface stoichiometry of the alternative Co2O2 bulk\ntermination of the (110) surface. Non-contact atomic force microscopy\ndemonstrates the presence of wide terraces separated by atomic steps in the\nannealed films that are not present in the as-grown structures; the step height\nof ~ 2.7 A corresponds to two atomic layers and confirms a single termination\nfor the annealed films, consistent with the LEED results. A model of the (1 *\n1) surfaces that allows for compensation of the polar surfaces is presented.",
        "positive": "Electrically tunable plasma excitations in AA-stacking multilayer\n  graphene: We use a tight-binding model and the random-phase approximation to study the\nCoulomb excitations in simple-hexagonal-stacking multilayer graphene and\ndiscuss the field effects. The calculation results include the energy bands,\nthe response functions, and the plasmon dispersions. A perpendicular electric\nfield is predicted to induce significant charge transfer and thus capable of\nmanipulating the energy, intensity, and the number of plasmon modes. This could\nbe further validated by inelastic light scattering or electron-energy-loss\nspectroscopy."
    },
    {
        "anchor": "Negative longitudinal magnetoresistance as a sign of a possible chiral\n  magnetic anomaly in the half-Heusler antiferromagnet DyPdBi: Magnetotransport investigation of a half-Heusler antiferromagnet DyPdBi\nrevealed hallmark features of Weyl semimetal: huge negative longitudinal\nmagnetoresistance and planar Hall effect. Both effects have recently been\nlinked to chiral magnetic anomaly - axial charge pumping between Weyl nodes.\nMagnetoresistance (MR) of single crystals of DyPdBi is very pronounced. In\nmagnetic field longitudinal to electrical current direction it reaches -80% and\nits relative difference with respect to that measured in transverse field\n(expressed as anisotropic magnetoresistance) is extremely strong: -60% at 10K\nand 14 T. The planar Hall effect in DyPdBi depends on temperature and magnetic\nfield in non-monotonous way, which has not been previously reported. We compare\nmagnetoresistance measured with voltage contacts on mid-line of the sample with\nthat measured with contacts on its edge, and show that the role of\ncurrent-jetting, an extrinsic source of anisotropic negative magnetoresistance,\nis marginal. We discuss that nature of the compound and sample quality exclude\nintrinsic sources of negative and anisotropic magnetoresistance other than weak\nlocalization and the chiral magnetic anomaly.",
        "positive": "Optical Anisotropy and Pinning of the Linear Polarization of Light in\n  Semiconductor Microcavities: We report a strong experimental evidence of the optical anisotropy in a\nCdTe-based microcavity: the polarization of light is pinned to one of the\ncrystallographic axes independently on the polarization of the excitation. The\npolarization degree depends strongly on the excitation power, reaching almost\n100 % in the stimulated regime. The relaxation time of the polarization is\nabout 1 ns. We argue that all this is an effect of a splitting of the polariton\ndoublet at k=0. We consider different sources for the splitting and conclude\nthat the most likely one is optical birefringence in the mirrors and/or the\ncavity."
    },
    {
        "anchor": "Relaxation Dynamics of Photoexcited Charge Carriers at the Bi(111)\n  Surface: Bi possesses intriguing properties due to its large spin-orbit coupling, e.g.\nas a constituent of topological insulators. While its electronic structure and\nthe dynamics of electron-phonon coupling have been studied in the past,\nphoto-induced charge carriers have not been observed in the early phases of\ntheir respective relaxation pathways. Using two-photon photoemission (2PPE) we\nfollow the de-excitation pathway of electrons along the unoccupied band\nstructure and into a bulk hole pocket. Two decay channels are found, one of\nwhich involves an Auger process. In the hole pocket, the electrons undergo an\nenergetic stabilization and recombine with the corresponding holes with an\ninverse rate of 2.5~ps. Our results contribute to the understanding of the\ncharge carrier relaxation processes immediately upon photo-excitation,\nparticularly along the $\\Gamma T$-line where the electron dynamics have not\nbeen probed with time-resolved 2PPE so far.",
        "positive": "Long-range-corrected hybrids including RPA correlation: We recently demonstrated a connection between the random phase approximation\n(RPA) and coupled cluster theory [J. Chem. Phys. 129, 231101 (2008)]. Based on\nthis result, we here propose and test a simple scheme for introducing\nlong-range RPA correlation into density functional theory. Our method provides\ngood thermochemical results and models van derWaals interactions accurately."
    },
    {
        "anchor": "The response of mechanical and electronic properties of graphane to the\n  elastic strain: Based on first-principles calculations, we resent a method to reveal the\nelastic properties of recently synthesized monolayer hydrocarbon, graphane. The\nin-plane stiffness and Poisson's ratio values are found to be smaller than\nthose of graphene, and its yielding strain decreases in the presence of various\nvacancy defects and also at high ambient temperature. We also found that the\nband gap can be strongly modified by applied strain in the elastic range.",
        "positive": "Band alignment and charge transfer in complex oxide interfaces: The synthesis of transition metal heterostructures is currently one of the\nmost vivid fields in the design of novel functional materials. In this paper we\npropose a simple scheme to predict \\emph{band alignment }and \\emph{charge\ntransfer} in complex oxide interfaces. For semiconductor heterostructures band\nalignment rules like the well known Anderson or Schottky-Mott rule are based on\ncomparison of the work function or electron affinity of the bulk components.\nThis scheme breaks down for oxides due to the invalidity of a single\nworkfunction approximation as recently shown (Phys. Rev. B 93, 235116; Adv.\nFunct. Mater. 26, 5471). Here we propose a new scheme which is built on a\ncontinuity condition of valence states originating in the compounds' shared\nnetwork of oxygen. It allows for the prediction of sign and relative amplitude\nof the intrinsic charge transfer, taking as input only information about the\nbulk properties of the components. We support our claims by numerical density\nfunctional theory simulations as well as (where available) experimental\nevidence. Specific applications include i) controlled doping of SrTiO$_3$\nlayers with the use of 4$d$ and 5$d$ transition metal oxides and ii) the\ncontrol of magnetic ordering in manganites through tuned charge transfer."
    },
    {
        "anchor": "A switchable two-dimensional electron gas based on ferroelectric\n  Ca:SrTiO$_3$: Two-dimensional electron gases (2DEGs) can form at the surface of oxides and\nsemiconductors or in carefully designed quantum wells and interfaces. Depending\non the shape of the confining potential, 2DEGs may experience a finite electric\nfield, which gives rise to relativistic effects such as the Rashba spin-orbit\ncoupling. Although the amplitude of this electric field can be modulated by an\nexternal gate voltage, which in turn tunes the 2DEG carrier density, sheet\nresistance and other related properties, this modulation is volatile. Here, we\nreport the design of a ''ferroelectric'' 2DEG whose transport properties can be\nelectrostatically switched in a non-volatile way. We generate a 2DEG by\ndepositing a thin Al layer onto a SrTiO$_3$ single crystal in which 1 percent\nof Sr is substituted by Ca to make it ferroelectric. Signatures of the\nferroelectric phase transition at 25 K are visible in the Raman response and in\nthe temperature dependences of the carrier density and sheet resistance that\nshows a hysteretic dependence on electric field as a consequence of\nferroelectricity. We suggest that this behavior may be extended to other oxide\n2DEGs, leading to novel types of ferromagnet-free spintronic architectures.",
        "positive": "Graphite and Hexagonal Boron-Nitride Possess the Same Interlayer\n  Distance. Why?: Graphite and hexagonal boron nitride (h-BN) are two prominent members of the\nfamily of layered materials possessing a hexagonal lattice. While graphite has\nnon-polar homo-nuclear C-C intra-layer bonds, h-BN presents highly polar B-N\nbonds resulting in different optimal stacking modes of the two materials in\nbulk form. Furthermore, the static polarizabilities of the constituent atoms\nconsiderably differ from each other suggesting large differences in the\ndispersive component of the interlayer bonding. Despite these major differences\nboth materials present practically identical interlayer distances. To\nunderstand this finding, a comparative study of the nature of the interlayer\nbonding in both materials is presented. A full lattice sum of the interactions\nbetween the partially charged atomic centers in h-BN results in vanishingly\nsmall monopolar electrostatic contributions to the interlayer binding energy.\nHigher order electrostatic multipoles, exchange, and short-range correlation\ncontributions are found to be very similar in both materials and to almost\ncompletely cancel out by the Pauli repulsions at physically relevant interlayer\ndistances resulting in a marginal effective contribution to the interlayer\nbinding. Further analysis of the dispersive energy term reveals that despite\nthe large differences in the individual atomic polarizabilities the\nhetero-atomic B-N C6 coefficient is very similar to the homo-atomic C-C\ncoefficient in the hexagonal bulk form resulting in very similar dispersive\ncontribution to the interlayer binding. The overall binding energy curves of\nboth materials are thus very similar predicting practically the same interlayer\ndistance and very similar binding energies."
    },
    {
        "anchor": "Effective Interaction Hamiltonian of Polaron Pairs in Diluted Magnetic\n  Semiconductors: The magnetic interaction of a pair of bound magnetic polarons (BMP) in\ndiluted magnetic semiconductors (DMS) is analyzed via a generalized\nHubbard-type Hamiltonian for two carriers in the presence of effective magnetic\nfields arising from the magnetic polarization of their respective polarons. For\nthe case where the magnetic fields at the two sites have equal magnitude but\nare allowed to have arbitrary directions, it is shown that the energy of the\ntwo polarons is minimized for a ferromagnetic configuration of the carrier\nspins (in contrast to the case of hydrogenic centers in nonmagnetic\nsemiconductors) if polaron fields are strong enough. A modified Heisenberg-type\nHamiltonian is constructed to describe the low energy states of the resulting\nsystem.",
        "positive": "Lattice thermal transport in group II-alloyed PbTe: PbTe, one of the most promising thermoelectric materials, has recently\ndemonstrated thermoelectric figure of merit ($ZT$) of above 2.0 when alloyed\nwith group II elements. The improvements are due mainly to significant\nreduction of lattice thermal conductivity ($\\kappa_{l}$), which was in turn\nattributed to nanoparticle precipitates. However, a fundamental understanding\nof various phonon scattering mechanisms within the bulk alloy is still lacking.\nIn this work, we apply the newly-developed density-functional-theory\n(DFT)-based compressive sensing lattice dynamics (CSLD) approach to model\nlattice heat transport in PbTe, MTe, and Pb$_{0.94}$M$_{0.06}$Te (M=Mg, Ca, Sr\nand Ba), compare our results with experimental measurements, with focus on\nstrain effect and mass disorder scattering. We find that (1) CaTe, SrTe and\nBaTe in the rock-salt structure exhibit much higher $\\kappa_{l}$ than PbTe,\nwhile MgTe in the same structure shows anomalously low $\\kappa_{l}$; (2)\nlattice heat transport of PbTe is extremely sensitive to static strain induced\nby alloying atoms in solid solution form; (3) mass disorder scattering plays a\nmajor role in reducing $\\kappa_{l}$ for Mg/Ca/Sr-alloyed PbTe through strongly\nsuppressing the lifetimes of intermediate- and high-frequency phonons, while\nfor Ba-alloyed PbTe, precipitated nanoparticles are also important."
    },
    {
        "anchor": "The strongest size in the inverse Hall-Petch relationship: Incorporating the bond-order-length-strength correlation mechanism [Sun CQ,\nProg Solid State Chem 35, 1 -159 (2007)] and Borns criterion for melting [J.\nChem. Phys. 7, 591(1939)] into the conventional Hall-Petch relationship has\nturned out an analytical expression for the size and temperature dependence of\nthe mechanical strength of nanograins, known as the inverse Hall-Petch\nrelationship (IHPR), that has long been a topic under debate regarding the\npossible mechanisms. Reproduction of the measured IHPR of Ni, NiP and TiO2\nnanocrystals revealed that: (i) the size induced energy densification and\ncohesive energy loss of nanograins originates the IHPR that could be activated\nin the contact mode of plastic deformation detection; (ii) the competition\nbetween the inhibition of atomic dislocations, via the surface energy density\ngain and the strain work hardening, and the activation for dislocations through\ncohesive energy loss determine the entire IHPR profile of a specimen; (iii) the\npresence of a soft quasisolid phase is responsible for the size-induced\nsoftening and the superplasticity as well of nanostructures; (iv) the bond\nnature involved and the T/Tm ratio between the temperature of operating and the\ntemperature of melting dictate the measured strongest sizes of a given\nspecimen.",
        "positive": "Field-induced canting of magnetic moments in GdCo5 at finite\n  temperature: first-principles calculations and high-field measurements: We present calculations and experimental measurements of the\ntemperature-dependent magnetization of a single crystal of GdCo$_5$ in magnetic\nfields of order 60 T. At zero temperature the calculations, based on\ndensity-functional theory in the disordered-local-moment picture, predict a\nfield-induced transition from an antiferromagnetic to a canted alignment of Gd\nand Co moments at 46.1 T. At higher temperatures the calculations find this\ncritical field to increase along with the zero-field magnetization. The\nexperimental measurements observe this transition to occur between 44-48 T at\n1.4 K. Up to temperatures of at least 100 K, the experiments continue to\nobserve the transition; however, at variance with the calculations, no strong\ntemperature dependence of the critical field is apparent. We assign this\ndifference to the inaccurate description of the zero-field magnetization of the\ncalculations at low temperatures, due to the use of classical statistical\nmechanics. Correcting for this effect, we recover a consistent description of\nthe high-field magnetization of GdCo$_5$ from theory and experiment."
    },
    {
        "anchor": "Carbon doping of GaN: Proof of the formation of electrically active\n  tri-carbon defects: Carbon doping is used to obtain semi-insulating GaN crystals. If the carbon\ndoping concentration exceeds $5*10^{17}$ $cm^{-3}$, the carbon atoms\nincreasingly form triatomic clusters. The tri-carbon defect structure is\nunambiguously proven by the isotope effect on the defects' local vibrational\nmodes (LVMs) originally found in samples containing carbon of natural isotopic\ncomposition $(~99 $%$ ^{12}C, ~1$%$ ^{13}C)$ at $1679$ $cm^{-1}$ and $1718$\n$cm^{-1}$. Number, spectral positions, and intensities of the LVMs for samples\nenriched with the $^{13}C$ isotope (~99 % and ~50 %) are consistently\ninterpreted on the basis of the harmonic oscillator model taking into account\nthe probability of possible isotope combinations. Including the polarization\ndependence of the LVM absorption, we show that the tri-carbon defects form a\ntriatomic molecule-like structure in two crystallographically different\nconfigurations: a basal configuration with the carbon bonds near the basal\nplane and an axial configuration with one of the carbon bonds along the c-axis.\nFinally, the disappearance of the LVMs under additional below-bandgap\nillumination is interpreted as defect recharging, i.e. the tri-carbon defects\npossess at least one charge state transition level within the bandgap and\ncontribute to optical absorption as well as to the electrical charge balance.",
        "positive": "Steering effects on growth instability during step-flow growth of Cu on\n  Cu(1,1,17): Kinetic Monte Carlo simulation in conjunction with molecular dynamics\nsimulation is utilized to study the effect of the steered deposition on the\ngrowth of Cu on Cu(1,1,17). It is found that the deposition flux becomes\ninhomogeneous in step train direction and the inhomogeneity depends on the\ndeposition angle, when the deposition is made along that direction. Steering\neffect is found to always increase the growth instability, with respect to the\ncase of homogeneous deposition. Further, the growth instability depends on the\ndeposition angle and direction, showing minimum at a certain deposition angle\noff-normal to (001) terrace, and shows a strong correlation with the\ninhomogeneous deposition flux. The increase of the growth instability is\nascribed to the strengthened step Erlich Schwoebel barrier effects that is\ncaused by the enhanced deposition flux near descending step edge due to the\nsteering effect."
    },
    {
        "anchor": "Mathematical modeling of magnetostrictive nanowires for sensor\n  application: Magnetostrictive wires of diameter in the nanometer scale have been proposed\nfor application as acoustic sensors [Downey et al., 2008], [Yang et al., 2006].\nThe sensing mechanism is expected to operate in the bending regime. In this\nwork we derive a variational theory for the bending of magnetostrictive\nnanowires starting from a full 3-dimensional continuum theory of\nmagnetostriction. We recover a theory which looks like a typical\nEuler-Bernoulli bending model but includes an extra term contributed by the\nmagnetic part of the energy. The solution of this variational theory for an\nimportant, newly developed magnetostricitve alloy called Galfenol (cf. [Clark\net al., 2000]) is compared with the result of experiments on actual nanowires\n(cf. [Downey, 2008]) which shows agreement.",
        "positive": "Millimeter wave analysis of the dielectric properties of oil shales: Natural sedimentation processes give rise to fine layers in shales. If these\nlayers alternate between organic-rich and organic-poor sediments, then the\ncontrast in dielectric properties gives rise to an effective birefringence as\nthe presence of hydrocarbons suppresses the dielectric constant of the host\nrock. We have measured these effects with a quasioptical millimeter wave setup\nthat is rapid and noncontacting. We find that the strength of this\nbirefringence and the overall dielectric permittivity provide two useful\ndiagnostic of the organic content of oil shales."
    },
    {
        "anchor": "First-principles based study of magnetic states and high-pressure\n  enthalpy landscape of manganese sulfide polymorphs: Using first-principles calculations in combination with special quasirandom\nstructure and occupation control matrix methods, we study the magnetic ordering\nand the effect of pressure on manganese sulfide polymorphs. At ambient\nconditions, MnS is commonly observed in paramagnetic rock-salt structure, but\nas temperature decreases at constant pressure it becomes antiferromagnetic. On\nthe other hand, at room temperature MnS has shown to undergo structural\ntransformations as pressure increases. Here, we show that our approach\ninvolving the ordering/disordering of the local magnetic moments in addition to\nthe explicit dealing with the localization of the Mn $d$-electrons produces\nenergy band gaps and local magnetic moments in excellent agreement with those\nobserved experimentally, particularly for paramagnetic MnS. Finally, we focus\non how MnS evolves under pressure and from its enthalpy landscape we identify\nat about 21~GPa, the structural transformation from rock-salt to orthorhombic\nMnP-type. This structural transformation resembles closely experimental results\nin which a new stable but unidentified MnS phase was previously reported.",
        "positive": "Environmental Effect on the UV Optical Absorption of Single-Walled\n  Carbon Nanotubes: We studied optical absorption of single-walled carbon nanotubes by varying\nthe dielectric environment. For the two different components of the broad UV\nabsorption feature conventionally referred to as the pi-plasmon, we find that\nthe component at 5.0 - 5.3 eV exhibits remarkable spectral changes, based on\nwhich we attribute this to a dipolar radial surface plasmon. However, the\ncomponent at ~4.5 eV remains unchanged, raising a fundamental question as to\nits conventional attribution. We discuss its relation with the absorption\nfeature at ~4.5 eV in graphite arising from an interband transition."
    },
    {
        "anchor": "Optically induced nonreciprocity by a plasmonic pump in semiconductor\n  wires: In most studies on all-optical diodes spatial asymmetry has been by necessity\napplied to break Lorentz reciprocity. Here we suggest a paradigm for optically\ninduced nonreciprocity in semiconductor wires which are spatially\nasymmetry-free and provide a very simple and efficient platform for plasmonic\ndevices. An azimuthal magnetic field induced by a plasmonic pump in the\nsemiconductor wire alters the material parameters and thus results in a\ncross-nonlinear modulation of the plasmonic signal. Peculiarly the nonlinear\nwavenumber shift has opposite signs for forward and backward signals whereas\nKerr or Kerr-like nonlinearity does not break Lorentz reciprocity in spatially\nsymmetric structures. This principle may open an avenue towards highly\nintegrated all-optical nonreciprocal devices.",
        "positive": "Laser doping for ohmic contacts in n-type Ge: We achieved ohmic contacts down to 5 K on standard n-doped Ge samples by\ncreating a strongly doped thin Ge layer between the metallic contacts and the\nGe substrate. Thanks to the laser doping technique used, Gas Immersion Laser\nDoping, we could attain extremely large doping levels above the solubility\nlimit, and thus reduce the metal/doped Ge contact resistance. We tested\nindependently the influence of the doping concentration and doped layer\nthickness, and showed that the ohmic contact improves when increasing the\ndoping level and is not affected when changing the doped thickness.\nFurthermore, we characterised the doped Ge/Ge contact, showing that at high\ndoping its contact resistance is the dominant contribution to the total contact\nresistance."
    },
    {
        "anchor": "Thermodynamic Stable Site for Interstitial alloy (N or O) in\n  bcc-Refractory Metals using Density Functional Theory: Plasticity in body centered cubic (bcc) refractory metals are largely due to\nthe stress tensor induced either by solute or thermal activation. The mechanism\nof the solute atom(s) residence causes instability in such metals. Earlier\nresearch have considered the mechanism of oxygen (O) or carbon (C) in tungsten\n(W), even though the major component of the environment is nitrogen (N). In\nthis article, the density functional theory (DFT) was employed to investigate\nthe thermodynamic stable site for an interstitial solute (N or O) in the bcc\nrefractory metals (Mo and Nb) by calculating the equilibrium and structural\nparameters, dissolution energetics and volumetric strain. The dissolution\nmechanism of all the relaxed solid solution structures were predicted to be an\nexothermic reaction from the supersaturated cell to the low concentration (1.82\nat.%) except for Mo-N solid solution. Convergence of volumetric strain was\nobserved at the low concentration of the solute. At this point, the solid\nsolution of Mo-N and Mo-O had a less measure of global stress (less distortion)\nat the octahedral (o) site while that of Nb-N and Nb-O were at the tetrahedral\n(t) site. This certainly shows why this two bcc-refractory metals in groups VB\n(Nb) and VIB (Mo) of the periodic table exhibit different deformation\nbehaviours giving their difference in site preference stability.",
        "positive": "Synthesis of ReN3 thin films by magnetron sputtering: Recently was reported a novel compound between rhenium and nitrogen,\nannounced with ReN2 composition. This compound was synthesized by the high\ntemperature and high pressure method. We found that the diffraction peaks of\nthis compound are in agreement with the x-ray pattern of a rhenium-nitrogen\nfilm, under the assumption that the film is oriented on the substrate. The film\nwas prepared by reactive magnetron sputtering, at room temperature, and\ndeposited on a silicon wafer. From the analysis of the diffractograms it could\nbe concluded that both materials share the same structure. By density\nfunctional calculation was found that the composition could be ReN3, instead of\nReN2, as stated before. The ReN3 fits in the Ama2 (40) orthorhombic space\ngroup, and by the existence of N3 anions it should be categorized as an azide;\nthat is, a nitrogen-rich compound. To reach high nitrogen concentrations by\nsputtering a crucial step is the target-poisoning. Under this regime of\ndeposition is ensured that the compound is formed simultaneously on the\nsubstrate and the target. The poisoned target is rarely used because of a\nreduced sputtering yield, but as shall see, it can be used as a novel synthetic\ntechnique."
    },
    {
        "anchor": "Coherent control of a V-type three-level system in a single quantum dot: In a semiconductor quantum dot, the Px and Py transitions to the polarization\neigenstates, |x> and |y>, naturally form a three-level V-type system. Using\nlow-temperature polarized photoluminescence spectroscopy, we have investigated\nthe exciton dynamics arising under strong laser excitation. We also explicitly\nsolved the density matrix equations for comparison with the experimental data.\nThe polarization of the exciting field controls the coupling between the\notherwise orthogonal states. In particular, when the system is initialized into\n|y>, a polarization-tailored pulse can swap the population into |x>, and\nvice-versa, effectively operating on the exciton spin.",
        "positive": "In situ resonant photoemission and X-ray absorption study of the BiFeO3\n  thin film: Multiferroic bismuth ferrite (BiFeO3) thin films were prepared by pulsed\nlaser deposition (PLD) technique. Electronic structures of the film have been\nstudied by in situ photoemission spectroscopy (PES) and x-ray absorption\nspectroscopy (XAS). Both the Fe 2p PES and XAS spectra show that Fe ion is\nformally in +3 valence state. The Fe 2p and O K edge XAS spectra indicate that\nthe oxygen octahedral crystal ligand field splits the unoccupied Fe 3d state to\nt2g and eg states. Valence band Fe 2p-3d resonant photoemission results\nindicate that hybridization between Fe 3d and O 2p plays important role in the\nmultiferroic BiFeO3 thin films."
    },
    {
        "anchor": "Magnetothermoelectric effects in graphene and their dependence on\n  scatterer concentration, magnetic field and band gap: Using a semiclassical Boltzmann transport equation (BTE) approach, we derive\nanalytical expressions for electric and thermoelectric transport coefficients\nof graphene in the presence and absence of a magnetic field. Scattering due to\nacoustic phonons, charged impurities and vacancies are considered in the model.\nSeebeck ($S_{xx}$) and Nernst ($N$) coefficients have been evaluated as\nfunctions of carrier density, temperature, scatterer concentration, magnetic\nfield and induced band gap, and the results are compared with experimental\ndata. $S_{xx}$ is an odd function of Fermi energy while $N$ is an even\nfunction, as observed in experiments. The peaks of both coefficients are found\nto increase with decreasing scatterer concentration and increasing temperature.\nFurthermore, opening a band gap decreases $N$ but increases $S_{xx}$. Applying\na magnetic field introduces an asymmetry in the variation of $S_{xx}$ with\nFermi energy across the Dirac point. The formalism is more accurate and\ncomputationally efficient than the conventional Green's function approach used\nto model transport coefficients and can be used to explore transport properties\nof other exotic materials.",
        "positive": "Stretched-exponential decay functions from a self-consistent model of\n  dielectric relaxation: There are many materials whose dielectric properties are described by a\nstretched exponential, the so-called Kohlrausch-Williams-Watts (KWW) relaxation\nfunction. Its physical origin and statistical-mechanical foundation have been a\nmatter of debate in the literature. In this paper we suggest a model of\ndielectric relaxation, which naturally leads to a stretched exponential decay\nfunction. Some essential characteristics of the underlying charge conduction\nmechanisms are considered. A kinetic description of the relaxation and charge\ntransport processes is proposed in terms of equations with time-fractional\nderivatives."
    },
    {
        "anchor": "Massive Dirac fermions in layered BaZnBi$_2$: Using angle-resolved photoemission spectroscopy (ARPES) and density\nfunctional theory (DFT) we study the electronic structure of layered\nBaZnBi$_2$. Our experimental results show no evidence of Dirac states in\nBaZnBi$_2$ originated either from the bulk or the surface. The calculated band\nstructure without spin-orbit interaction shows several linear dispersive band\ncrossing points throughout the Brillouin zone. However, as soon as the\nspin-orbit interaction is turned on, the band crossing points are significantly\ngapped out. The experimental observations are in good agreement with our DFT\ncalculations. These observations suggest that the Dirac fermions in BaZnBi$_2$\nare trivial and massive. We also observe experimentally that the electronic\nstructure of BaZnBi$_2$ comprises of several linear dispersive bands in the\nvicinity of Fermi level dispersing to a wider range of binding energy.",
        "positive": "Composition-tuned magneto-optical Kerr effect in L10-MnxGa films with\n  giant perpendicular anisotropy: We report the large polar magnetooptical Kerr effect in L10-MnxGa epitaxial\nfilms with giant perpendicular magnetic anisotropy in a wide composition range.\nThe Kerr rotation was enhanced by a factor of up to 10 by decreasing Mn atomic\nconcentration, which most likely arises from the variation of the effective\nspin-orbit coupling strength, compensation effect of magnetic moments at\ndifferent Mn atom sites, and overall strain. The Kerr ellipticity and the\nmagnitude of the complex Kerr angle is found to have more complex\ncomposition-dependence that varies with the photon energy. These L10-MnxGa\nfilms show large Kerr rotation of up to 0.10o, high reflectivity of 35%-55% in\na wide wavelength range of 400~850 nm, and giant magnetic anisotropic field of\nup to 210 kOe, making them an interesting material system for emerging\nspintronics and terahertz modulator applications."
    },
    {
        "anchor": "Lateral Confinement of Electrons in Vicinal N-polar AlGaN/GaN\n  Heterostructure: We studied orientation dependent transport in vicinal N-polar AlGaN/GaN\nheterostructures. We observed significant anisotropy in the current carrying\ncharge parallel and perpendicular to the miscut direction. A quantitative\nestimate of the charge anisotropy was made based on gated TLM and Hall\nmeasurements. The formation of electro-statically confined one-dimensional\nchannels is hypothesized to explain charge anisotropy. A mathematical model was\nused to verify that polarization charges distributed on miscut structure can\ncreate lateral one-dimensional confinement in vicinal substrates. This\npolarization-engineered electrostatic confinement observed is promising for new\nresearch on low-dimensional physics and devices besides providing a template\nfor manufacturable one-dimensional devices.",
        "positive": "Simulation of the Einstein-de Haas effect combining molecular and spin\n  dynamics: The spin and lattice dynamics of a ferromagnetic nanoparticle are studied via\nmolecular dynamics and with semi-classical spin dynamics simulations where spin\nand lattice degrees of freedom are coupled via a dynamic uniaxial anisotropy\nterm. We show that this model conserves total angular momentum, whereas spin\nand lattice angular momentum are not conserved. We carry out simulations of the\nthe Einstein-de Haas effect for a Fe nanocluster with more than 500 atoms that\nis free to rotate, using a modified version of the open-source spinlattice\ndynamics code (SPILADY). We show that the rate of angular momentum transfer\nbetween spin and lattice is proportional to the strength of the magnetic\nanisotropy interaction. The addition of the anisotropy allows full spin-lattice\nrelaxation to be achieved on previously reported timescales of \\sim 100 ps and\nfor tight-binding magnetic anisotropy energies comparable to those of small Fe\nnanoclusters."
    },
    {
        "anchor": "Addressing Raman features of individual layers in isotopically labeled\n  Bernal stacked bilayer graphene: The most important bands for the evaluation of strain in graphene (the 2D and\n2D prime modes) are investigated. It is shown that for Bernal-stacked bilayers,\nthe two-phonon Raman features have three different components that can be\nassigned to processes originating solely from the top graphene layer, bottom\ngraphene layer, and from a combination of processes originating both from the\ntop and bottom layers. The individual components of the 2D and 2D prime modes\nare disentangled. The reported results enable addressing the properties of\nindividual graphene layers in isotopically labelled turbostratic and\nBernalstacked graphene systems.",
        "positive": "Tuning alloy disorder in diluted magnetic semiconductors in high fields\n  to 89 T: Alloy disorder in II-VI diluted magnetic semiconductors (DMS) is typically\nreduced when the local magnetic spins align in an applied magnetic field. An\nimportant and untested expectation of current models of alloy disorder,\nhowever, is that alloy fluctuations in many DMS compounds should increase again\nin very large magnetic fields of order 100 tesla. Here we measure the disorder\npotential in a Zn$_{.70}$Cd$_{.22}$Mn$_{.08}$Se quantum well via the low\ntemperature photoluminescence linewidth, using a new magnet system to 89 T.\nAbove 70 T, the linewidth is observed to increase again, in accord with a\nsimple model of alloy disorder."
    },
    {
        "anchor": "Ferroelectricity of Li-doped silver niobate (Ag,Li)NbO3: Phase evolution in (Ag1-xLix)NbO3 (ALN) solid solution was investigated by\nX-ray diffraction technique, dielectric and polarization measurements. It is\nshown that small substitution of Ag with Li gives rise to an\northorhombic-rhombohedral structural transformation in ABO3-perovskite silver\nniobate at room temperature. Structural refinements indicate that both A- and\nB-site displacements contribute to the spontaneous polarization of the\nferroelectric phase with symmetry R3c. Increasing Li-concentration enhances the\nferroelectric rhombohedral distortion, resulting in the increase of the\npara-ferroelectric phase transition temperature and the polarization of the\nsolid solutions.",
        "positive": "Adjusting the melting point of a model system via Gibbs-Duhem\n  integration: application to a model of Aluminum: Model interaction potentials for real materials are generally optimized with\nrespect to only those experimental properties that are easily evaluated as\nmechanical averages (e.g., elastic constants (at T=0 K), static lattice\nenergies and liquid structure). For such potentials, agreement with experiment\nfor the non-mechanical properties, such as the melting point, is not guaranteed\nand such values can deviate significantly from experiment. We present a method\nfor re-parameterizing any model interaction potential of a real material to\nadjust its melting temperature to a value that is closer to its experimental\nmelting temperature. This is done without significantly affecting the\nmechanical properties for which the potential was modeled. This method is an\napplication of Gibbs-Duhem integration [D. Kofke, Mol. Phys.78, 1331 (1993)].\nAs a test we apply the method to an embedded atom model of aluminum [J. Mei and\nJ.W. Davenport, Phys. Rev. B 46, 21 (1992)] for which the melting temperature\nfor the thermodynamic limit is 826.4 +/- 1.3K - somewhat below the experimental\nvalue of 933K. After re-parameterization, the melting temperature of the\nmodified potential is found to be 931.5K +/- 1.5K."
    },
    {
        "anchor": "Non-trivial spin-texture of the coaxial Dirac cones on the surface of\n  topological crystalline insulator SnTe: We present first principles calculations of the nontrivial surface states and\ntheir spin-textures in the topological crystalline insulator SnTe. The surface\nstate dispersion on the [001] surface exhibits four Dirac-cones centered along\nthe intersection of the mirror plane and the surface plane. We propose a simple\nmodel of two interacting coaxial Dirac cones to describe both the surface state\ndispersion and the associated spin-texture. While the out-of-the-plane spin\npolarization is zero due to the crystalline and time-reversal symmetries, the\nin-plane spin texture shows helicity with some distortion due to the\ninteraction of the two coaxial Dirac cones, indicating a nontrivial mirror\nChern number of -2, distinct from the value of -1 in $Z_{2}$ topological\ninsulator such as Bi/Sb alloys or Bi$_2$Se$_3$. The surface state dispersion\nand its spin-texture would provide an experimentally accessible way to\ndetermine the nontrivial mirror Chern number.",
        "positive": "Intrinsic room temperature ferromagnetism in Co-implanted ZnO: We report on the structural and magnetic properties of a cobalt-implanted ZnO\nfilm grown on a sapphire substrate. X-ray diffraction and transmission electron\nmicroscopy reveal the presence of a (10-10)-oriented hexagonal Co phase in the\nAl2O3 sapphire substrate, but not in the ZnO film. Co clusters, with a diameter\nof is about 5-6 nm, form a Co rich layer in the substrate close to the\nZnO/Al2O3 interface. Magnetization measurements indicate that there exist two\ndifferent magnetic phases in the implanted region. One originates from the Co\nclusters in Al2O3, the other one belongs to a homogeneous ferromagnetic phase\nwith a ferromagnetic Curie temperature far above room temperature and can be\nattributed to Co substitution on Zn sites in the ZnO layer. We have observed\nmagnetic dichroism at the Co L2,3 and O K edges at room temperature as well as\nthe multiplet structure in x-ray absorption spectra around the Co L3 edge,\nsupporting the intrinsic nature of the observed ferromagnetism in Co-implanted\nZnO film. The magnetic moment per substituted cobalt is found about 2.81 Bohr\nmagneton which is very close to the theoretical expected value of 3 Bohr\nmagneton per Co atom for Co 2+ in its high spin state."
    },
    {
        "anchor": "Microscopic Theory of Ultrafast Out-of-Equilibrium Dynamics in Magnetic\n  Insulators. Unraveling the Magnon-Phonon Coupling: The interaction between lattice and spins is at the heart of an extremely\nintriguing ultrafast dynamics in magnetic materials. In this work we formulate\na general non-equilibrium theory that disentangles the complex interplay\nbetween them in a THz laser-excited antiferromagnetic insulator. The theory\nprovides a quantitative description of the transient energy flow between the\nspin and lattice sub-systems, subject to magnon-phonon and phonon-phonon\nscatterings, giving rise to finite life-times of the quasiparticles and to the\nequilibration time of the system. We predict a novel kind of scattering process\nwhere two magnons of opposite polarizations decay into a phonon, previously\nomitted in the literature. The theory is combined with first-principle\ncalculations and then applied to simulate a realistic dynamics of NiO. The main\nrelaxation channels and hot spots in the reciprocal space, giving the strongest\ncontribution to the energy transfer between phonons and magnons are identified.\nThe diverse interaction strengths lead to distinct coupled dynamics of the\nlattice and spin systems and subsequently to different equilibration\ntimescales.",
        "positive": "Interface-driven giant tunnel magnetoresistance in (111)-oriented\n  junctions: We theoretically study the tunnel magnetoresistance (TMR) effect in\n(111)-oriented junctions Co/MgO/Co(111) and Ni/MgO/Ni(111). The Co-based\njunction is shown to have a TMR ratio over 2000$\\%$, which is one order higher\nthan that of the Ni-based one. The high TMR ratio is attributed to the\ninterfacial resonance effect: The interfacial $d$-$p$ antibonding states are\nformed close to the Fermi level in the majority-spin channel and these states\nin both interfaces resonate with each other. This differs essentially from the\nconventional coherent tunneling mechanism of high TMR ratios in\nFe(Co)/MgO/Fe(Co)(001)."
    },
    {
        "anchor": "Early stages of dissolution corrosion in 316L and DIN 1.4970 austenitic\n  stainless steels with and without anticorrosion coatings in static liquid\n  lead-bismuth eutectic (LBE) at 500$^\\circ$C: This work addresses the early stages ($\\le$1000 h) of the dissolution\ncorrosion behavior of 316L and DIN 1.4970 austenitic stainless steels in\ncontact with oxygen-poor (C$_O$ < 10$^-$$^8$ mass%), static liquid lead-bismuth\neutectic (LBE) at 500{\\deg}C for 600-1000 h. The objective of this study was to\ndetermine the relative early-stage resistance of the uncoated steels to\ndissolution corrosion and to assess the protectiveness of select candidate\ncoatings (Cr$_2$AlC, Al$_2$O$_3$, V$_2$Al$_x$C$_y$). The simultaneous exposure\nof steels with intended differences in microstructure and thermomechanical\nstate showed the effects of steel grain size, density of annealing/deformation\ntwins, and secondary precipitates on the steel dissolution corrosion behavior.\nThe findings of this study provide recommendations on steel manufacturing with\nthe aim of using the steels to construct Gen-IV lead-cooled fast reactors.",
        "positive": "Evolutionary construction of formation energy convex hull: Practical\n  scheme and application to carbon-hydrogen binary system: We present an evolutionary construction technique of formation energy convex\nhull to search for thermodynamically stable compounds. In this technique,\ncandidates with a wide variety of chemical compositions and crystal structures\nare created by systematically applying evolutionary operators, \"mating\",\n\"mutation\", and \"adaptive mutation\", to two target compounds, and the convex\nhull is directly updated through the evolution. We applied the technique to\ncarbon-hydrogen binary system at 10 GPa and obtained 15 hydrocarbons within the\nconvex hull distance less than 0.5 mRy/atom: graphane, polybutadiene,\npolyethylene, butane, ethane, methane, three molecular compounds of ethane and\nmethane, and six molecular compounds of methane and hydrogen. These results\nsuggest that our evolutionary construction technique is useful for the\nexploration of stable phases under extreme conditions and the synthesis of new\ncompounds."
    },
    {
        "anchor": "Topological Origin of Fracture Toughening in Complex Solids: the\n  Viewpoint of Rigidity Theory: In order to design tougher materials, it is crucial to understand the\nrelationship between their composition and their resistance to fracture. To\nthis end, we investigate the fracture toughness of usual sodium silicate\nglasses (NS) and complex calcium--silicate--hydrates (CSH), the binding phase\nof cement. Their atomistic structure is described in the framework of the\ntopological constraints theory, or rigidity theory. We report an analogous\nrigidity transition, driven by pressure in NS and by composition in CSH.\nRelying both on simulated and available experimental results, we show that\noptimally constrained isostatic systems show improved fracture toughness. The\nflexible to stressed--rigid transition is shown to be correlated to a\nductile-to-brittle transition, with a local minimum of the brittleness for\nisostatic system. This fracture toughening arises from a reversible molecular\nnetwork, allowing optimal stress relaxation and crack blunting behaviors. This\nopens the way to the discovery of high-performance materials, designed at the\nmolecular scale.",
        "positive": "Sr flux stability against oxidation in oxide-MBE environment: flux,\n  geometry, and pressure dependence: Maintaining stable fluxes for multiple source elements is a challenging task\nwhen the source materials have significantly different oxygen affinities in a\ncomplex-oxide molecular-beam-epitaxy (MBE) environment. Considering that Sr is\none of the most easily oxidized and widely used element in various complex\noxides, we took Sr as a probe to investigate the flux stability problem in a\nnumber of different conditions. Source oxidation was less for higher flux,\nextended port geometry, and un-melted source shape. The extended port geometry\nalso eliminated the flux transient after opening a source shutter as observed\nin the standard port. We also found that the source oxidation occurred more\neasily on the crucible wall than on the surface of the source material. Atomic\noxygen, in spite of its stronger oxidation effectiveness, did not make any\ndifference in source oxidation as compared to molecular oxygen in this\ngeometry. Our results may provide a guide for solutions to the source oxidation\nproblem in oxide-MBE system."
    },
    {
        "anchor": "Room Temperature Electrocaloric Effect in Layered Ferroelectric CuInP2S6\n  for Solid State Refrigeration: A material with reversible temperature change capability under an external\nelectric field, known as the electrocaloric effect (ECE), has long been\nconsidered as a promising solid-state cooling solution. However, electrocaloric\n(EC) performance of EC materials generally is not sufficiently high for real\ncooling applications. As a result, exploring EC materials with high performance\nis of great interest and importance. Here, we report on the ECE of\nferroelectric materials with van der Waals layered structure (CuInP2S6 or CIPS\nin this work in particular). Over 60% polarization charge change is observed\nwithin a temperature change of only 10 K at Curie temperature. Large adiabatic\ntemperature change (|{\\Delta}T|) of 3.3 K, isothermal entropy change\n(|{\\Delta}S|) of 5.8 J kg-1 K-1 at |{\\Delta}E|=142.0 kV cm-1 at 315 K (above\nand near room temperature) are achieved, with a large EC strength\n(|{\\Delta}T|/|{\\Delta}E|) of 29.5 mK cm kV-1. The ECE of CIPS is also\ninvestigated theoretically by numerical simulation and a further EC performance\nprojection is provided.",
        "positive": "Ferroelectricity in Hafnia Controlled via Surface Electrochemical State: Ferroelectricity in binary oxides including hafnia and zirconia have riveted\nthe attention of the scientific community due to highly unconventional physical\nmechanisms and the potential for integration of these materials into\nsemiconductor workflows. Over the last decade, it has been argued that\nbehaviors such as wake-up phenomena and an extreme sensitivity to electrode and\nprocessing conditions suggests that ferroelectricity in these materials is\nstrongly coupled with additional mechanisms, with possible candidates including\nthe ionic subsystem or strain. Here we argue that the properties of these\nmaterials emerge due to the interplay between the bulk competition between\nferroelectric and structural instabilities, similar to that in classical\nantiferroelectrics, coupled with non-local screening mediated by the finite\ndensity of states at surfaces and internal interfaces. Via decoupling of\nelectrochemical and electrostatic controls realized via environmental and\nultra-high vacuum PFM, we show that these materials demonstrate a rich spectrum\nof ferroic behaviors including partial pressure- and temperature-induced\ntransitions between FE and AFE behaviors. These behaviors are consistent with\nan antiferroionic model and suggest novel strategies for hafnia-based device\noptimization."
    },
    {
        "anchor": "Morphology of Critically-Sized Crystalline Nuclei at Shear-Induced\n  Crystal Nucleation in Amorphous Solid: In this work we study morphological characteristics of the critically-sized\ncrystalline nuclei at initial stage of the shear-induced crystallization of a\nmodel single-component amorphous (glassy) system. These characteristics are\nestimated quantitatively through statistical treatment of the non-equilibrium\nmolecular dynamics simulation results for the system under steady shear at\nvarious (fixed) values of the shear rate $\\dot\\gamma$ and at different\ntemperatures. It is found that the sheared glassy system is crystallized\nthrough nucleation mechanism. From analysis of a time-dependent trajectories of\nthe largest crystalline nuclei, the critical size $n_{c}$ and the nucleation\ntime $\\tau_{c}$ were defined. It is shown that the critically-sized nuclei in\nthe system are oriented within the shear-gradient $xy$-plane at moderate and\nhigh shear rates; and a tilt angle of the oriented nuclei depends on the shear\nrate. At extremely high shear rates and at shear deformation of the system more\nthan $60$\\%, the tilt angle of the nuclei tends to take the value\n$\\simeq45^\\circ$ respective to the shear direction. We found that this feature\ndepends weakly on the temperature. Asphericity of the nucleus shape increases\nwith increasing shear rate, that is verified by increasing value of the\nasphericity parameter and by the contour of the pair distribution function\ncalculated for the particles of the critically-sized nuclei. The critical size\nincreases with increasing shear rate according to the power-law,\n$n_{c}\\propto(\\dot\\gamma\\tau_{c})^{1/3}$, whereas the shape of the\ncritically-sized nucleus changes from spherical to the elongated ellipsoidal.\nWe found that the $n_{c}$-dependencies of the nuclei deformation parameter\nevaluated for the system at different temperatures and shear rates are\ncollapsed into unified master-curve.",
        "positive": "On the mechanism of gas adsorption for pristine, defective and\n  functionalized graphene: Defect is no longer deemed an adverse aspect of graphene. Contrarily, it can\npave ways of extending applicability of graphene. Here, we discuss the effects\nof three types of defects on graphene: carbon deficiency, adatom (single Fe)\ndopant and introduction of functional groups (carboxyl, pyran group) on NO2 gas\nadsorption via density functional theory method. We have observed that the\nunsaturated carbon in defected graphene is highly active to attract NO2\nmolecules. Our study suggests that introducing Fe on graphene can enhance the\nNO2 adsorption process. Adsorption energy calculations suggest the enhancement\nin NO2 adsorption is more profound for Fe-doped mono and tetra vacant graphene\nthan Fe doped bi- and tri-vacant graphene. This study could potentially be\nuseful in developing adsorption-based applications of graphene."
    },
    {
        "anchor": "Geometric treatment of conduction electron scattering by crystal lattice\n  strains and dislocations: A theory for conduction electron scattering by inhomogeneous crystal lattice\nstrains is developed, based on the differential geometric treatment of\ndeformations in solids. The resulting fully covariant Schr\\\"odinger equation\nshows that the electrons can be described as moving in a non-Euclidean\nbackground space in the continuum limit of the deformed lattice. Unlike\nprevious work, the formalism is applicable to cases involving purely elastic\nstrains as well as discrete and continuous distributions of dislocations --- in\nthe latter two cases it clearly demarcates the effects of the dislocation\nstrain field and core and differentiates between elastic and plastic strain\ncontributions respectively. The electrical resistivity due to the strain field\nof edge dislocations is then evaluated using perturbation theory and the\nBoltzmann transport equation. The resulting numerical estimate for Cu shows\ngood agreement with experimental values, indicating that the electrical\nresistivity of edge dislocations is not entirely due to the core, contrary to\ncurrent models. Possible application to the study of strain effects in\nconstrained quantum systems is also discussed.",
        "positive": "Attosecond time-domain measurement of core-excitonic decay in magnesium\n  oxide: Excitation of ionic solids with extreme ultraviolet pulses creates localized\ncore-excitons, which in some cases couple strongly to the lattice. Here,\ncore-excitonic states of magnesium oxide are studied in the time domain at the\nMg $\\text{L}_{2,3}$ edge with attosecond transient reflectivity spectroscopy.\nAttosecond pulses trigger the excitation of these short-lived quasiparticles,\nwhose decay is perturbed by time-delayed near infrared optical pulses. Combined\nwith a few-state theoretical model, this reveals that the optical pulse shifts\nthe energy of bright core-exciton states as well as induces features arising\nfrom dark core-excitons. We report coherence lifetimes for the first two\ncore-excitons of $2.3 \\pm 0.2$ and $1.6 \\pm 0.5$ femtoseconds and show that\nthese short lifetimes are primarily a consequence of strong exciton-phonon\ncoupling, disclosing the drastic influence of structural effects in this\nultrafast relaxation process."
    },
    {
        "anchor": "Analyzing the Carrier Mobility in Transition-metal Dichalcogenide MoS2\n  Field-effect Transistors: Transition-metal dichalcogenides (TMDCs) are important class of\ntwo-dimensional (2D) layered materials for electronic and optoelectronic\napplications, due to their ultimate body thickness, sizable and tunable\nbandgap, and decent theoretical room-temperature mobility of hundreds to\nthousands cm2/Vs. So far, however, all TMDCs show much lower mobility\nexperimentally because of the collective effects by foreign impurities, which\nhas become one of the most important limitations for their device applications.\nHere, taking MoS2 as an example, we review the key factors that bring down the\nmobility in TMDC transistors, including phonons, charged impurities, defects,\nand charge traps. We introduce a theoretical model that quantitatively captures\nthe scaling of mobility with temperature, carrier density and thickness. By\nfitting the available mobility data from literature over the past few years, we\nare able to obtain the density of impurities and traps for a wide range of\ntransistor structures. We show that interface engineering such as oxide surface\npassivation, high-k dielectrics and BN encapsulation could effectively reduce\nthe impurities, leading to improved device performances. For few-layer TMDCs,\nwe analytically model the lopsided carrier distribution to elucidate the\nexperimental increase of mobility with the number of layers. From our analysis,\nit is clear that the charge transport in TMDC samples is a very complex problem\nthat must be handled carefully. We hope that this Review can provide new\ninsights and serve as a starting point for further improving the performance of\nTMDC transistors.",
        "positive": "Surface passivation by graphene in the lubrication of iron: A comparison\n  with bronze: It has been recently reported that graphene is able to significantly reduce\nthe friction coefficient of steel-on-steel sliding contacts. The microscopic\norigin of this behavior has been attributed to the mechanical action of load\ncarrying capacity. However, a recent work highlighted the importance of the\nchemical action of graphene. According to this work graphene reduces the\nadhesion of iron interfaces by reducing the surface energy thanks to a\npassivation effect. The aim of the present work is to clarify the still debated\nlubricating behavior of graphene flakes. We perform pin-on-disc experiments\nusing liquid dispersed graphene solution as a lubricant. Two different\nmaterials, pure iron and bronze are tested against 100Cr6 steel. Raman\nspectroscopy is used to analyze the surfaces after the friction tests. The\nresults of these tests prove that graphene flakes have a beneficial effect on\nthe friction coefficient. At the same time they show a tendency of graphene to\npassivate the native iron surfaces that are exposed during sliding as a\nconsequence of wear."
    },
    {
        "anchor": "Coherent Coupling of WS_2 Monolayers with Metallic Photonic\n  Nanostructures at Room Temperature: Room temperature strong coupling of WS_2 monolayer exciton transitions to\nmetallic Fabry-Perot and plasmonic optical cavities is demonstrated. A Rabi\nsplitting of 101 meV is observed for the Fabry-Perot cavity, more than double\nthose reported to date in other 2D materials. The enhanced magnitude and\nvisibility of WS_2 monolayer strong coupling is attributed to the larger\nabsorption coefficient, the narrower linewidth of the A exciton transition, and\ngreater spin-orbit coupling. For WS_2 coupled to plasmonic arrays, the Rabi\nsplitting still reaches 60 meV despite the less favorable coupling conditions,\nand displays interesting photoluminescence features. The unambiguous signature\nof WS_2 monolayer strong coupling in easily fabricated metallic resonators at\nroom temperature suggests many possibilities for combining light-matter\nhybridization with spin and valleytronics.",
        "positive": "First-principles prediction of sub-10 nm skyrmions in Pd/Fe bilayers on\n  Rh(111): We show that stable skyrmions with diameters of a few nanometers can emerge\nin atomic Pd/Fe bilayers on the Rh(111) surface. Based on density functional\ntheory we calculate the exchange and the Dzyaloshinskii-Moriya interaction as\nwell as the magnetocrystalline anisotropy energy. The later two terms are\ndriven by spin-orbit coupling and significantly reduced compared to Pd/Fe\nbilayers on Ir(111) as expected since Rh and Ir are isoelectronic $4d$ and $5d$\ntransition-metals. However, there is still a spin spiral ground state at zero\nmagnetic field. Atomistic spin dynamics simulations show that a skyrmion phase\noccurs at small magnetic fields of $\\sim$ 1 T. Skyrmion diameters amount to 2\nto 8 nm and skyrmion lifetimes are up to 1 hour at temperatures of 25 to 45 K."
    },
    {
        "anchor": "Deorbitalized meta-GGA Exchange-Correlation Functionals in Solids: A procedure for removing explicit orbital dependence from\nmeta-generalized-gradient approximation (mGGA) exchange-correlation functionals\nby converting them into Laplacian-dependent functionals recently was developed\nby us and shown to be successful in molecules. It uses an approximate kinetic\nenergy density functional (KEDF) parametrized to Kohn-Sham results (not\nexperimental data) on a small training set. Here we present extensive\nvalidation calculations on periodic solids that demonstrate that the same\ndeorbitalization with the same parametrization also is successful for those\nextended systems. Because of the number of stringent constraints used in its\nconstruction and its recent prominence, our focus is on the SCAN meta-GGA.\nCoded in \\textsc{vasp}, the deorbitalized version, SCAN-L, can be as much as a\nfactor of three faster than original SCAN, a potentially significant gain for\nlarge-scale ab initio molecular dynamics.",
        "positive": "Phase Transformation in Self-Organized Carbon Tribolayers: The simplest way to obtain thin carbon layers is to draw or rub with a\ngraphite rod. During rubbing, forces of friction acting in graphite/substrate\ntribological system cause drastic changes in the structure of the interface\nstratum developing thereby stable self-organized and ordered thin structure. We\npresent a pioneering experimental investigation of structural and morphological\ntransformations in carbon tribolayers (CTL). By optical microscopy observation\nit is found that CTL is a multilayer structure, the essential building block of\nwhich is a transparent phase shaped as a lamina in-between the surface and\nbottom disordered layers of CTL. The surface of the lamina exhibits non-linear\nelectrical conductivity near zero bias on I-V characteristics. The optical\nproperties of the whole CTL are mostly controlled by physical processes\noccurring in the transparent lamina. The Raman spectrum of CTL contains narrow\nbands at 1,589 cm-1 and 1,346 cm-1 corresponding to G and D bands of carbon\ncrystal lattice. The observed features are interpreted using the relationship\nbetween the bond length and corresponding band frequency, r2{\\omega}= const.\nOptical absorption of CTL has a feature at 4.6 eV originating from strong\nelectron-hole interaction. From comparative analysis of experimental data,\nstructural-spectral correspondence is found. It is concluded that because of\nphase transformation during rubbing, a carbon structure consisting of sp3\nlamina with a nano-scaled thick sp2 layer on the top is shaped."
    },
    {
        "anchor": "Phase diagram studies for the growth of (Mg,Zr):SrGa$_{12}$O$_{19}$\n  crystals: By differential thermal analysis a concentration field suitable for the\ngrowth of Zr, Mg codoped strontium hexagallate crystals was observed that\ncorresponds well with experimental results from Mateika and Laurien, J. Crystal\nGrowth 52 (1981) 566-572. It was shown that the melting point of doped crystal\nis ca. 60 K higher than that of undoped crystals. This higher melting points\nindicates hexagallate phase stabilization by Zr, Mg codoping, and increases the\ngrowth window, compared to undoped SrO-Ga$_2$O$_3$ melts.",
        "positive": "Structural, dielectric and ferroelectric studies of thermally stable and\n  efficient energy storage ceramic material: (Na0.5-xKxBi0.5-xLax)TiO3: The structural, dielectric and ferroelectric properties of lead-free\n(Na0.5-xKxBi0.5-xLax)TiO3 powders synthesized by sol-gel self-combustion method\nwere investigated. Rietveld refinement of Synchrotron x-ray diffraction data\nconfirms pure single phase rhombohedral crystal structure with R3c space group\nfor all the compositions and anti-phase octahedral tilting angle decreased with\nincrease in composition x. Homogeneity and elemental proportions were confirmed\nby Energy dispersive x-ray spectrometry. The temperature-dependent dielectric\nstudy has shown two diffuse type of dielectric anomaly for all the samples, due\nto A-site disorder in the lattice, which has been assigned to two-has\ntransitions: ferroelectric to anti-ferroelectric and anti-ferroelectric to the\nparaelectric phase transition. The transition temperature of these phase\ntransitions is found to decrease as a function of composition. Thermal\nstability range of dielectric constant increases from ~100C to 220C as a\nfunction of composition. Stable dielectric constant first increases, from 1557\n10 % for parent compound, with the composition, highest for 6 % composition\nwith emid ~ 2508 10 % for the temperature range ~180 C to 340C and after that\ndecreases to 1608 10 % for 12 % but remain higher than the parent compound\nNa0.5Bi0.5TiO3. Ferroelectric measurements have shown monotonously decreasing\ncoercive field as a function of the composition due to a decrease in grain\nsize, confirmed by microstructural studies using Field Emission Scanning\nElectron Microscope. Exponential increases in the energy storage efficiency\nfrom ~ 17 % to 87 % as a function of composition have also observed. These\ntypes of materials, with stable high dielectric constant and low tan delta,\nhave a vast scope in the field of the thermally stable dielectric constant\nmaterials and energy storage applications."
    },
    {
        "anchor": "High-pressure lattice dynamics in bulk single-crystal BaWO4: Room-temperature Raman scattering has been measured in barium tungstate\n(BaWO4) up to 16 GPa. We report the pressure dependence of all the Raman-active\nfirst-order phonons of the tetragonal scheelite phase (BaWO4-I, space group\nI41/a), which is stable at normal conditions. As pressure increases the Raman\nspectrum undergoes significant changes around 6.9 GPa due to the onset of the\nstructural phase transition to the monoclinic BaWO4-II phase (space group\nP21/n). This transition is only completed above 9.5 GPa. A further change in\nthe spectrum is observed at 7.5 GPa related to a scheelite-to-fergusonite\ntransition. The scheelite, BaWO4-II, and fergusonite phases coexist up to 9.0\nGPa due to the sluggishness of the I?II phase transition. Further to the\nexperimental study, we have performed ab initio lattice dynamics calculations\nthat have greatly helped us in assigning and discussing the pressure behaviour\nof the observed Raman modes of the three phases.",
        "positive": "Materials Design by Quantum-Chemical and other Theoretical/Computational\n  Means: Applications to Energy Storage and Photoemissive Materials: The present paper discusses some recent developments in the field of rational\ndesign for energy storage and photoemissive materials. Recent and new examples\nof designer materials for Li-ion and Li-air type batteries with high capacity\nand energy/power density as well as photoemissive materials with low\nworkfunctions and improved brightness are discussed as illustrative examples of\nhow quantum-chemical and other theoretical computational means can be used for\nrational materials design."
    },
    {
        "anchor": "The formation of well-defined crystalline structures by UV laser\n  irradiation of amorphous silicon films: This study provides a new insight into the processes which occur when thin\nfilm hydrogenated amorphous silicon is subjected to UV laser irradiation in the\npresence of oxygen. It achieves this by observing the effects of subjecting the\nfilms to progressively increasing laser radiation doses. This reveals that an\narray of nuclei is first created, leading to the formation of a well-defined\ncrystalline network, consistent with the structure of silicon oxide. Further\nirradiation results in the formation of cone-like structures on the crystalline\nnetwork, due to silicon-oxygen bond breakage and migration of the resultant\nsilicon-rich material. Eventually the cone-like structures become the dominant\nfeatures, but remain interconnected by nanowire remnants of the original\ncrystalline structure.",
        "positive": "Influence of Local Defects on the Dynamics of O-H Bond Breaking and\n  Formation on a Magnetite Surface: The transport of H adatoms across oxide supports plays an important role in\nmany catalytic reactions. We investigate the dynamics of H/Fe3O4(001) between\n295 and 382 K. By scanning tunneling microscopy at frame rates of up to 19.6\nfps, we observe the thermally activated switching of H between two O atoms on\nneighboring Fe rows. This switching rate changes in proximity to a defect,\nexplained by density functional theory as a distortion in the Fe-O lattice\nshortening the diffusion path. Quantitative analysis yields an apparent\nactivation barrier of 0.94 +/- 0.07 eV on a pristine surface. The present work\nhighlights the importance of local techniques in the study of atomic-scale\ndynamics at defective surfaces such as oxide supports."
    },
    {
        "anchor": "Quantifying Confidence in Density Functional Theory Predicted Magnetic\n  Ground States: The success of descriptor-based material design relies on eliminating bad\ncandidates and keeping good candidates for further investigation. While DFT has\nbeen widely successfully for the former, often times good candidates are lost\ndue to the uncertainty associated with the DFT-predicted material properties.\nUncertainty associated with DFT predictions has gained prominence and has led\nto the development of exchange correlation functionals that have built-in error\nestimation capability. In this work, we demonstrate the use of built-in error\nestimation capabilities within the BEEF-vdW exchange correlation functional for\nquantifying the uncertainty associated with the magnetic ground state of\nsolids. We demonstrate this approach by calculating the uncertainty estimate\nfor the energy difference between the different magnetic states of solids and\ncompare them against a range of GGA exchange correlation functionals as is done\nin many first principles calculations of materials. We show that this estimate\nreasonably bounds the range of values obtained with the different GGA\nfunctionals. The estimate is determined as a post-processing step and thus\nprovides a computationally robust and systematic approach to estimating\nuncertainty associated with predictions of magnetic ground states. We define a\nconfidence value (c-value) that incorporates all calculated magnetic states in\norder to quantify the concurrence of the prediction at the GGA level and argue\nthat predictions of magnetic ground states from GGA level DFT is incomplete\nwithout an accompanying c-value. We demonstrate the utility of this method\nusing a case study of Li and Na-ion cathode materials and the c-value metric\ncorrectly identifies that GGA level DFT will have low predictability for\nNaFePO$_4$F.",
        "positive": "An ab initio non-equilibrium Green's function approach to charge\n  transport: dithiolethine: We present a novel ab initio non-equilibrium approach to calculate the\ncurrent across a molecular junction. The method rests on a wave function based\nfull ab initio description of the central region of the junction combined with\na tight binding approximation for the electrodes in the frame of the Keldysh\nGreen's function formalism. Our procedure is demonstrated for a dithiolethine\nmolecule between silver electrodes. The main conducting channel is identified\nand the full current-voltage characteristic is calculated."
    },
    {
        "anchor": "Speeding up the solution of the Bethe-Salpeter equation by a double-grid\n  method and Wannier interpolation: The Bethe-Salpeter equation is a widely used approach to describe optical\nexcitations in bulk semiconductors. It leads to spectra that are in very good\nagreement with experiment, but the price to pay for such accuracy is a very\nhigh computational burden. One of the main bottlenecks is the large number of\nk-points required to obtain converged spectra. In order to circumvent this\nproblem we propose a strategy to solve the Bethe-Salpeter equation based on a\ndouble-grid technique coupled to a Wannier interpolation of the Kohn-Sham band\nstructure. This strategy is then benchmarked for a particularly difficult case,\nthe calculation of the absorption spectrum of GaAs, and for the well studied\ncase of Si. The considerable gains observed in these cases fully validate our\napproach, and open the way for the application of the Bethe-Salpeter equation\nto large and complex systems.",
        "positive": "Enhanced Gas-Flow-Induced Voltage in Graphene: We show by systemically experimental investigation that gas-flow-induced\nvoltage in monolayer graphene is more than twenty times of that in bulk\ngraphite. Examination over samples with sheet resistances ranging from 307 to\n1600 {\\Omega}/sq shows that the induced voltage increase with the resistance\nand can be further improved by controlling the quality and doping level of\ngraphene. The induced voltage is nearly independent of the substrate materials\nand can be well explained by the interplay of Bernoulli's principle and the\ncarrier density dependent Seebeck coefficient. The results demonstrate that\ngraphene has great potential for flow sensors and energy conversion devices."
    },
    {
        "anchor": "Crossover behavior in the magnetoresistance of thin flakes of the\n  topological material ZrTe5: ZrTe5 is a layered material that exhibits intricate topological effects.\nIntensive theoretically and experimental efforts have been devoted to try to\nunderstand the physics in this materials. In this paper the temperature\ndependent magneto-transport properties of ZrTe5 thin flakes are investigated. A\ncharacteristic temperature T* is observed in the temperature dependence of\nthree different types of magnetoresistance simultaneously, which are the\nsaturated Hall anomaly, the chiral anomaly and the longitudinal\nmagnetoresistance. Furthermore, the value of T* decreases monotonically from\n200K to 160K with increasing thickness of the ZrTe5 thin flakes from 42nm to\n89nm. Temperature induced topological phase transitions are attributed to the\ncause of such anomaly in the three types of magnetoresistance at T*. Our\nfindings provide a multi-parameter indicator for the emergence of topological\nphase transition in ZrTe5 and could be extended to the study of other\ntopological materials. The temperature dependence of the three types of\nmagnetoresistance also shed light on the role of anomalous Hall Effect in the\ntransport properties of ZrTe5.",
        "positive": "How metal films de-wet substrates - identifying the kinetic pathways and\n  energetic driving forces: We study how single-crystal chromium films of uniform thickness on W(110)\nsubstrates are converted to arrays of three-dimensional (3D) Cr islands during\nannealing. We use low-energy electron microscopy (LEEM) to directly observe a\nkinetic pathway that produces trenches that expose the wetting layer. Adjacent\nfilm steps move simultaneously uphill and downhill relative to the staircase of\natomic steps on the substrate. This step motion thickens the film regions where\nsteps advance. Where film steps retract, the film thins, eventually exposing\nthe stable wetting layer. Since our analysis shows that thick Cr films have a\nlattice constant close to bulk Cr, we propose that surface and interface stress\nprovide a possible driving force for the observed morphological instability.\nAtomistic simulations and analytic elastic models show that surface and\ninterface stress can cause a dependence of film energy on thickness that leads\nto an instability to simultaneous thinning and thickening. We observe that\nde-wetting is also initiated at bunches of substrate steps in two other\nsystems, Ag/W(110) and Ag/Ru(0001). We additionally describe how Cr films are\nconverted into patterns of unidirectional stripes as the trenches that expose\nthe wetting layer lengthen along the W[001] direction. Finally, we observe how\n3D Cr islands form directly during film growth at elevated temperature. The Cr\nmesas (wedges) form as Cr film steps advance down the staircase of substrate\nsteps, another example of the critical role that substrate steps play in 3D\nisland formation."
    },
    {
        "anchor": "The investigation of YAlO3-NdAlO3 system, synthesis and characterization: The binary phase diagram of the YAlO3 (YAP) - NdAlO3 (NAP) system was\ndetermined by differential thermal analysis (DTA) and X-ray powder diffraction\n(XRD) measurements. High purity nanocrystalline powders and small single\ncrystals of Y_{1-x}Nd_{x}AlO_3 (0 \\leq x \\leq 1) have been produced\nsuccessfully by modified sol-gel (Pechini) and micro-pulling-down methods,\nrespectively. Both end members show high mutual solubility >25% in the solid\nphase, with a miscibility gap for intermediate compositions. A solid solution\nwith x \\approx 0.2 melts azeotropic ca. 20 degrees below pure YAP. Such\ncrystals can be grown from the melt without segregation. The narrow\nsolid/liquid region near the azeotrope point could be measured with a \"cycling\"\nDTA measurement technique.",
        "positive": "Saturation Magnetization of Inorganic/polymer Nanocomposites Higher than\n  That of Their Inorganic Magnetic Component: Herein, some magnetic nanoparticles (MNP)/clay/polymer nanocomposites have\nbeen prepared, whose saturation magnetization is higher than that of pure oleic\nacid coated MNP component. The existence of unique 'nano-network' structure and\ntight three-phase nano-interface in the nanocomposites contribute to the\nsurprising saturation magnetization."
    },
    {
        "anchor": "Tailoring Magnetism of Perpendicularly Magnetized MnxGa Epitaxial Films\n  on GaAs for Practical Applications: MnxGa films with high perpendicular anisotropy, coercivity and energy product\nhave great application potential in ultrahigh-density perpendicular recording,\npermanent magnets, spin-transfer-torque memory and oscillators,\nmagneto-resistance sensors and ferromagnetic metal/semiconductor\nheterostructure devices. Here we present a comprehensive diagram of effective\nmagnetism-tailoring of perpendicularly magnetized MnxGa films grown on III-V\nsemiconductor GaAs by using molecular-beam epitaxy for the first time, by\nsystematically investigating the wide-range composition and detailed\npost-growth annealing effects. We show that the (001)-orientated MnxGa films\nwith L10 or D022 ordering could be crystallized on GaAs in a very wide\ncomposition range from x=0.76 to 2.6. L10-ordered MnxGa films show robust\nmagnetization, high remanent ratio, giant perpendicular anisotropy, high\nintrinsic and extrinsic coercivity, and large energy product, which make this\nkind of material favorable for perpendicular magnetic recording,\nhigh-performance spintronic devices and permanent magnet applications. In\ncontrast, D022-ordered films exhibit lower perpendicular anisotropy and weaker\nmagnetism. Post-growth annealing MnxGa films studies reveal high\nthermal-stability up to 450 oC, and effective tailoring of magnetic properties\ncan be realized by prolonging annealing at 450 oC. These results would be\nhelpful for understanding this kind of material and designing new spintronic\ndevices for specific practical applications.",
        "positive": "Calculating magnetic interactions in organic electrides: We present our calculation results for organic magnetic electrides. In order\nto identify the `cavity' electrons, we use maximally-localized Wannier\nfunctions and `empty atom' technique. The estimation of magnetic coupling is\nthen performed based on magnetic force linear response theory. Both short- and\nlong-range magnetic interactions are calculated with a single self-consistent\ncalculation of a primitive cell. With this scheme we investigate four different\norganic electrides whose magnetic properties have been partly unknown or under\ndebate. Our calculation results unveil the nature of magnetic moment and their\ninteractions, and justify or defy the validity of preassumed spin models. Our\nwork not only provides useful insight to understand magnetic electrides but\nalso suggests a new paradigm to study the related materials."
    },
    {
        "anchor": "Dynamics of growing carbon nanotube interfaces probed by machine\n  learning-enabled molecular simulations: Carbon nanotubes (CNTs) are currently considered a successor to silicon in\nfuture nanoelectronic devices. To realize this, controlled growth of\ndefect-free nanotubes is required. Until now, the understanding of atomic-scale\nCNT growth mechanisms provided by molecular dynamics simulations has been\nhampered by their short timescales. Here, we develop an efficient and accurate\nmachine learning force field, DeepCNT-22, to simulate the complete growth of\ndefect-free single-walled CNTs (SWCNTs) on iron catalysts at near-microsecond\ntimescales. We provide atomic-level insight into the nucleation and growth\nprocesses of SWCNTs, including the evolution of the tube-catalyst interface and\nthe mechanisms underlying defect formation and healing. Our simulations\nhighlight the maximization of SWCNT-edge configurational entropy during growth\nand how defect-free CNTs can grow ultralong if carbon supply and temperature\nare carefully controlled.",
        "positive": "Photoluminescence switching in a two-dimensional atomic crystal: Two-dimensional materials are an emerging class of new materials with a wide\nrange of electrical and optical properties and potential applications.\nSingle-layer structures of semiconducting transition metal dichalcogenides are\ngaining increasing attention for use in field-effect transistors. Here, we\nreport a photoluminescence switching effect based on single-layer WSe2\ntransistors. Dual gates are used to tune the photoluminescence intensity. In\nparticular, a side-gate is utilized to control the location of ions within a\nsolid polymer electrolyte to form an electric double layer at the interface of\nelectrolyte and WSe2 and induce a vertical electric field. Additionally, a\nback-gate is used to apply a 2nd vertical electric field. An on-off ratio of\nthe light emission up to 90 was observed under constant pump light intensity.\nIn addition, a blue shift of the photoluminescence line up to 36 meV was\nobserved. We attribute this blue shift to the decrease of exciton binding\nenergy due to the change of nonlinear in-plane dielectric constant and use it\nto determine the 3rd order off-diagonal susceptibility \\c{hi}^((3)\n)=3.50*10^(-19)m2/V2."
    },
    {
        "anchor": "Cu Modified SrTiO3 Perovskites Toward Enhanced Water Gas Shift\n  Catalysis: A Combined Experimental and Computational Study: The water gas shift reaction (WGS) is important and widely applied in the\nproduction of H2. Cu modified perovskites are promising catalysts for WGS\nreactions in hydrogen generation. However, the structure-dependent stability\nand reaction pathways of such materials remain unclear. Herein, we report\ncatalytically active Cu modified SrTiO3 (nominally SrTi1-xCuxO3) prepared by a\nmodified polymeric precursor method. Microstructural analysis revealed a\npartially segregated CuO phase in the as-prepared materials. Operando X-ray\ndiffraction and absorption spectroscopy showed the reduction of CuO into a\nstable metallic phase under conditions of WGS reactions for all compositions.\nAmong the characterized materials, the x = 0.20 composition showed the highest\nturnover frequency, lowest activation energy, and the highest WGS rate at 300C.\nAccording to density functional calculations, the formation of CuO is\nenergetically less favorable compared with SrTiO3, explaining why the\nsegregated CuO phase on the SrTiO3 surface is reduced to Cu during the\ncatalytic reaction, while SrTiO3 remains. For x = 0.20, the size of the\nsegregated CuO phase is optimum for facilitating the catalytic reaction. In\ncontrast, a higher Cu content (x = 0.3) results in an aggregation of smaller\nCuO particles, resulting in fewer surface active sites and a net decrease in\ncatalytic performance.",
        "positive": "Directed self-organization of graphene nanoribbons on SiC: Realization of post-CMOS graphene electronics requires production of\nsemiconducting graphene, which has been a labor-intensive process. We present\ntailoring of silicon carbide crystals via conventional photolithography and\nmicroelectronics processing to enable templated graphene growth on\n4H-SiC{1-10n} (n = 8) crystal facets rather than the customary {0001} planes.\nThis allows self-organized growth of graphene nanoribbons with dimensions\ndefined by those of the facet. Preferential growth is confirmed by Raman\nspectroscopy and high-resolution transmission electron microscopy (HRTEM)\nmeasurements, and electrical characterization of prototypic graphene devices is\npresented. Fabrication of > 10,000 top-gated graphene transistors on a 0.24 cm2\nSiC chip demonstrates scalability of this process and represents the highest\ndensity of graphene devices reported to date."
    },
    {
        "anchor": "Strain accommodation through facet matching in\n  La$_\\text{1.85}$Sr$_\\text{0.15}$CuO$_\\text{4}$/Nd$_\\text{1.85}$Ce$_\\text{0.15}$CuO$_\\text{4}$\n  ramp-edge junctions: Scanning nano-focused X-ray diffraction (nXRD) and high-angle annular\ndark-field scanning transmission electron microscopy (HAADF-STEM) are used to\ninvestigate the crystal structure of ramp-edge junctions between\nsuperconducting electron-doped Nd$_\\text{1.85}$Ce$_\\text{0.15}$CuO$_\\text{4}$\nand superconducting hole-doped La$_\\text{1.85}$Sr$_\\text{0.15}$CuO$_\\text{4}$\nthin films, the latter being the top layer. On the ramp, a new growth mode of\nLa$_\\text{1.85}$Sr$_\\text{0.15}$CuO$_\\text{4}$ with a 3.3 degree tilt of the\nc-axis is found. We explain the tilt by developing a strain accommodation model\nthat relies on facet matching, dictated by the ramp angle, indicating that a\ncoherent domain boundary is formed at the interface. The possible implications\nof this growth mode for the creation of artificial domains in morphotropic\nmaterials are discussed.",
        "positive": "Electrical charging effects on the sliding friction of a model\n  nano-confined ionic liquid: Recent measurements suggest the possibility to exploit ionic liquids (ILs) as\nsmart lubricants for nano-contacts, tuning their tribological and rheological\nproperties by charging the sliding interfaces. Following our earlier\ntheoretical study of charging effects on nanoscale confinement and squeezout of\na model IL, we present here molecular dynamics simulations of the frictional\nand lubrication properties of that model under charging conditions.First we\ndescribe the case when two equally charged plates slide while being held\ntogether to a confinement distance of a few molecular layers.The shear sliding\nstress is found to rise as the number of IL layers decreases stepwise. However\nthe shear stress shows, within each given number of layers, only a weak\ndependence upon the precise value of the normal load, a result in agreement\nwith data extracted from recent experiments.We subsequently describe the case\nof opposite charging of the sliding plates, and follow the shear stress when\nthe charging is slowly and adiabatically reversed in the course of time, under\nfixed load. Despite the fixed load, the number and structure of the confined IL\nlayers changes with changing charge, and that in turn drives strong friction\nvariations. The latter involve first of all charging-induced freezing of the IL\nfilm, followed by a discharging-induced melting, both made possible by the\nnanoscale confinement. Another mechanism for charging-induced frictional\nchanges is a shift of the plane of maximum shear from mid-film to the\nplate-film interface, and viceversa. While these occurrences and results\ninvariably depend upon the parameters of the model IL and upon its specific\ninteraction with the plates, the present study helps identifying a variety of\npossible behavior, obtained under very simple assumptions, while connecting it\nto an underlying equilibrium thermodynamics picture."
    },
    {
        "anchor": "Machine Learning for Atomic Forces in a Crystalline Solid:\n  Transferability to Various Temperatures: Recently, machine learning has emerged as an alternative, powerful approach\nfor predicting quantum-mechanical properties of molecules and solids. Here,\nusing kernel ridge regression and atomic fingerprints representing local\nenvironments of atoms, we trained a machine-learning model on a crystalline\nsilicon system in order to directly predict the atomic forces at a wide range\nof temperatures. Our idea is to construct a machine-learning model using a\nquantum-mechanical data set taken from canonical-ensemble simulations at a\nhigher temperature, or an upper bound of the temperature range. With our model,\nthe force prediction errors were about 2% or smaller with respect to the\ncorresponding force ranges, in the temperature region between 300 and 1650 K.\nWe also verified the applicability to a larger system, ensuring the\ntransferability with respect to system size.",
        "positive": "Polarization sensitive solar-blind detector based on a-plane AlGaN: We report polarization-sensitive solar-blind metal-semiconductor-metal UV\nphotodetectors based on (11-20) a-plane AlGaN. The epilayer shows anisotropic\noptical properties confirmed by polarization-resolved transmission and\nphotocurrent measurements, in good agreement with band structure calculations."
    },
    {
        "anchor": "Controlling Curie temperature in (Ga,Ms)As through location of the Fermi\n  level within the impurity band: The ferromagnetic semiconductor (Ga,Mn)As has emerged as the most studied\nmaterial for prototype applications in semiconductor spintronics. Because\nferromagnetism in (Ga,Mn)As is hole-mediated, the nature of the hole states has\ndirect and crucial bearing on its Curie temperature TC. It is vigorously\ndebated, however, whether holes in (Ga,Mn)As reside in the valence band or in\nan impurity band. In this paper we combine results of channeling experiments,\nwhich measure the concentrations both of Mn ions and of holes relevant to the\nferromagnetic order, with magnetization, transport, and magneto-optical data to\naddress this issue. Taken together, these measurements provide strong evidence\nthat it is the location of the Fermi level within the impurity band that\ndetermines TC through determining the degree of hole localization. This finding\ndiffers drastically from the often accepted view that TC is controlled by\nvalence band holes, thus opening new avenues for achieving higher values of TC.",
        "positive": "Spin-spiral state of a Mn monolayer on W(110) studied by soft x-ray\n  absorption spectroscopy at variable temperatures: The noncollinear magnetic state of epitaxial Mn monolayers on tungsten (110)\ncrystal surfaces is investigated by means of soft x-ray absorption\nspectroscopy, to complement earlier spin-polarized STM experiments. X-ray\nabsorption spectra (XAS), x-ray linear dichroism (XLD) and x-ray magnetic\ncircular dichroism (XMCD) Mn L23-edge spectra were measured in the temperature\nrange from 8 to 300 K and compared to results of fully-relativistic ab initio\ncalculations. We show that antiferromagnetic (AFM) helical and cycloidal\nspirals give rise to significantly different Mn L23-edge XLD signals, enabling\nthus to distinguish between them. It follows from our results that the magnetic\nground state of a Mn monolayer on W(110) is an AFM cycloidal spin spiral. Based\non temperature-dependent XAS, XLD and field-induced XMCD spectra we deduce that\nmagnetic properties of the Mn monolayer on W(110) vary with temperature, but\nthis variation lacks a clear indication of a phase transition in the\ninvestigated temperature range up to 300 K - even though a crossover exists\naround 170 K in the temperature dependence of XAS branching ratios and in XLD\nprofiles."
    },
    {
        "anchor": "Heterometallic Metal-Organic Frameworks of MOF-5 and UiO-66 Families:\n  Insight from Computational Chemistry: We study the energetic stability and structural features of bimetallic\nmetal-organic frameworks. Such heterometallic MOFs, which can result from\npartial substitutions between two types of cations, can have specific physical\nor chemical properties used for example in catalysis or gas adsorption. We work\nhere to provide through computational chemistry a microscopic understanding of\nbimetallic MOFs and the distribution of cations within their structure. We\ndevelop a methodology based on a systematic study of possible cation\ndistributions at all cation ratios by means of quantum chemistry calculations\nat the density functional theory level. We analyze the energies of the\nresulting bimetallic frameworks and correlate them with various disorder\ndescriptors (functions of the bimetallic framework topology, regardless of\nexact atomic positions). We apply our methodology to two families of MOFs known\nfor heterometallicity: MOF-5 (with divalent metal ions) and UiO-66 (with\ntetravalent metal ions). We observe that bimetallicity is overall more\nfavorable for pairs of cations with sizes very close to each other, owing to a\ncharge transfer mechanism inside secondary building units. For cation pairs\nwith significant mutual size difference, metal mixing is globally less\nfavorable, and the energy signifantly correlates with the coordination\nenvironment of linkers, determining their ability to adapt the mixing-induced\nstrains. This effect is particularly strong in the UiO-66 family because of\nhigh cluster coordination number.",
        "positive": "Ballistic conductivity of graphene channel with p-n junction on\n  ferroelectric domain wall: We study the impact of the ferroelectric domain wall on the ballistic\nconductance of the single-layer graphene channel in the heterostructure\ngraphene / physical gap / ferroelectric film using Wentzel-Kramers-Brillouin\napproximation. Both self-consistent numerical modeling of the electric field\nand space charge dynamics in the heterostructure and approximate analytical\ntheory show that the domain wall contact with the surface creates p-n junction\nin graphene channel. We calculated that the carriers' concentration induced in\ngraphene by uncompensated ferroelectric dipoles originated from the spontaneous\npolarization abrupt near the surface can reach the values of 1019 m-2 order,\nwhich is in two orders higher than it can be obtained for the gate doped\ngraphene on non-ferroelectric substrates. Therefore we predict that graphene\nchannel with the p-n junction caused by ferroelectric domain wall would be\ncharacterized by rather high ballistic conductivity."
    },
    {
        "anchor": "Enhanced thermopower and low thermal conductivity in p-type\n  polycrystalline ZrTe5: Thermoelectric properties of polycrystalline p-type ZrTe5 are reported in\ntemperature (T) range 2 - 340 K. Thermoelectric power (S) is positive and\nreaches up to 458 uV/K at 340 K on increasing T. The value of Fermi energy 16\nmeV, suggests low carrier density of ~ 9.5 X 10^18 cm-3. A sharp anomaly in S\ndata is observed at 38 K, which seems intrinsic to p-type ZrTe5. The thermal\nconductivity value is low (2 W/m-K at T = 300 K) with major contribution from\nlattice part. Electrical resistivity data shows metal to semiconductor\ntransition at T ~ 150 K and non-Arrhenius behavior in the semiconducting\nregion. The figure of merit zT (0.026 at T = 300 K) is ~ 63% higher than HfTe5\n(0.016), and better than the conventional SnTe, p-type PbTe and bipolar\npristine ZrTe5 compounds.",
        "positive": "Super-harmonic injection locking of nano-contact spin-torque vortex\n  oscillators: Super-harmonic injection locking of single nano-contact (NC) spin-torque\nvortex oscillators (STVOs) subject to a small microwave current has been\nexplored. Frequency locking was observed up to the fourth harmonic of the STVO\nfundamental frequency $f_{0}$ in microwave magneto-electronic measurements. The\nlarge frequency tunability of the STVO with respect to $f_{0}$ allowed the\ndevice to be locked to multiple sub-harmonics of the microwave frequency\n$f_{RF}$, or to the same sub-harmonic over a wide range of $f_{RF}$ by tuning\nthe DC current. In general, analysis of the locking range, linewidth, and\namplitude showed that the locking efficiency decreased as the harmonic number\nincreased, as expected for harmonic synchronization of a non-linear oscillator.\nTime-resolved scanning Kerr microscopy (TRSKM) revealed significant differences\nin the spatial character of the magnetization dynamics of states locked to the\nfundamental and harmonic frequencies, suggesting significant differences in the\ncore trajectories within the same device. Super-harmonic injection locking of a\nNC-STVO may open up possibilities for devices such as nanoscale frequency\ndividers, while differences in the core trajectory may allow mutual\nsynchronisation to be achieved in multi-oscillator networks by tuning the\nspatial character of the dynamics within shared magnetic layers."
    },
    {
        "anchor": "Vibrational relaxation dynamics in layered perovskite quantum wells: Organic-inorganic layered perovskites are two-dimensional quantum wells with\nlayers of lead-halide octahedra stacked between organic ligand barriers. The\ncombination of their dielectric confinement and ionic sublattice results in\nexcitonic excitations with substantial binding energies that are strongly\ncoupled to the surrounding soft, polar lattice. However, the ligand environment\nin layered perovskites can significantly alter their optical properties due to\nthe complex dynamic disorder of soft perovskite lattice. Here, we observe the\ndynamic disorder through phonon dephasing lifetimes initiated by ultrafast\nphotoexcitation employing high-resolution resonant impulsive stimulated Raman\nspectroscopy of a variety of ligand substitutions. We demonstrate that\nvibrational relaxation in layered perovskite formed from flexible alkyl-amines\nas organic barriers is fast and relatively independent of the lattice\ntemperature. Relaxation in aromatic amine based layered perovskite is slower,\nthough still fast relative to pure inorganic lead bromide lattices, with a rate\nthat is temperature dependent. Using molecular dynamics simulations, we explain\nthe fast rates of relaxation by quantifying the large anharmonic coupling of\nthe optical modes with the ligand layers and rationalize the temperature\nindependence due to their amorphous packing. This work provides a molecular and\ntime-domain depiction of the relaxation of nascent optical excitations and\nopens opportunities to understand how they couple to the complex layered\nperovskite lattice, elucidating design principles for optoelectronic devices.",
        "positive": "Two-dimensional Weyl Half Semimetal and Tunable Quantum Anomalous Hall\n  Effect in Monolayer PtCl$_{3}$: We propose a new topological quantum state of matter---the two-dimensional\n(2D) Weyl half semimetal (WHS), which features 2D Weyl points at Fermi level\nbelonging to a single spin channel, such that the low-energy electrons are\ndescribed by fully spin-polarized 2D Weyl fermions. We predict its realization\nin the ground state of monolayer PtCl$_3$. We show that the material is a half\nmetal with an in-plane magnetization, and its Fermi surface consists of a pair\nof fully spin-polarized Weyl points protected by a mirror symmetry, which are\nrobust against spin-orbit coupling. Remarkably, we show that the WHS state is a\ncritical state at the topological phase transition between two quantum\nanomalous Hall insulator phases with opposite Chern numbers, such that a\nswitching between quantum anomalous Hall states can be readily achieved by\nrotating the magnetization direction. Our findings demonstrate that WHS offers\nnew opportunity to control the chiral edge channels, which will be useful for\ndesigning new topological electronic devices."
    },
    {
        "anchor": "On a relationship between the collective migration of surface atoms in\n  microclusters and the saddle points on the potential energy surface: Plenty of saddles on a multidimensional potential energy surface(PES) of\ntwo-dimensional microclusters, where atoms are interacting via Morse potential,\nare numerically located. The reaction paths emanating from the two types of the\nlocal minima, which represent the compact and the non-compact shape of Morse\nclusters, to their neighboring saddles on PES are elucidated. By associating\nthe reaction path crossing these saddles with the atomic rearrangements,we\nevaluate the barrier height corresponding to various characteristic atomic\nmotion accompanied by the {\\it floaters} (i.e. surface atoms popped out of the\ncluster surface). Our findings are summarized as: (i)The saddle points implying\nthe {\\it gliding motion} of a single {\\it floater} over the cluster surface\nyields extremely small values of the energy barriers regardless of the shapes\nof clusters. In particular, the {\\it gliding motion} of a train composed of a\nfew surface atoms also appears as the low-lying saddles. As a result, the\nbarrier height corresponding to the {\\it simultaneous gliding motion}, which is\na manifestation of the reaction path crossing the higher-index saddles on PES,\nis significantly low. (ii)A surface rearrangement, where {\\it floaters} are\ncreated or annihilated, implies relatively high barrier energy which is still\naccessible below melting point. (iii)On the other hand, the atomic motion,\nwhere atoms located deep inside of the clusters are rearranged as well as\nsurface atoms, yields extremely high barrier energies. Some relations between\nthese results and the recent experimental study of the surface cluster\ndiffusion are also pointed out.",
        "positive": "Consistent set of band parameters for the group-III nitrides AlN, GaN,\n  and InN: We have derived consistent sets of band parameters (band gaps, crystal\nfield-splittings, band gap deformation potentials, effective masses, Luttinger\nand EP parameters) for AlN, GaN, and InN in the zinc-blende and wurtzite phases\nemploying many-body perturbation theory in the G0W0 approximation. The G0W0\nmethod has been combined with density-functional theory (DFT) calculations in\nthe exact-exchange optimized effective potential approach (OEPx) to overcome\nthe limitations of local-density or gradient-corrected DFT functionals (LDA and\nGGA). The band structures in the vicinity of the Gamma-point have been used to\ndirectly parameterize a 4x4 k.p Hamiltonian to capture non-parabolicities in\nthe conduction bands and the more complex valence-band structure of the\nwurtzite phases. We demonstrate that the band parameters derived in this\nfashion are in very good agreement with the available experimental data and\nprovide reliable predictions for all parameters which have not been determined\nexperimentally so far."
    },
    {
        "anchor": "Frequency dependent negative capacitance of (Ba0.6Sr0.4)(ZrxTi1-x)O3\n  thin films grown on La0.9Sr1.1NiO4 buffered SrTiO3 substrate: Ba0.6Sr0.4TiO3 and (Ba0.6Sr0.4)(Zr0.3Ti0.7)O3 thin films were deposited on\nLa0.9Sr1.1NiO4 buffered SrTiO3 substrates. (Ba0.6Sr0.4)(Zr0.3Ti0.7)O3 film\n(2.77 nF) showed one order large capacitance compared to that of Ba0.6Sr0.4TiO3\nfilm (270 pF) at 100 kHz. (Ba0.6Sr0.4)(Zr0.3Ti0.7)O3 film showed negative\ncapacitance at f >3 MHz except for f=5.05 to 7.36 MHz, and 10.4 to 13.4 MHz,\nwhere it showed positive capacitance. Tunability of the Ba0.6Sr0.4TiO3 film\n(~15%) is much lower than that of the (Ba0.6Sr0.4)(Zr0.3Ti0.7)O3 film (30 to\n65%, both normal and inverse). A significant change of the tunability was\nobserved at frequencies f>500 kHz for the (Ba0.6Sr0.4)(Zr0.3Ti0.7)O3 film\nshowing inverse tunability, this can be attributed to the negative capacitance\neffect, where current lags behind the voltage. (Ba0.6Sr0.4)(Zr0.3Ti0.7)O3 film\n(6.87x10-6 A/cm2) showing one order high leakage current density than BST film\n(1.32x10-7 A/cm2). Ba0.6Sr0.4TiO3 film showed large grain size (140 nm) and\nsurface roughness (11.5 nm) and (Ba0.6Sr0.4)(Zr0.3Ti0.7)O3 film showed small\ngrain size (80 nm) and roughness (2.3 nm).",
        "positive": "Room temperature deformation in the Fe$_7$Mo$_6$ $\u03bc$-Phase: The role of TCP phases in deformation of superalloys and steels is still not\nfully resolved. In particular, the intrinsic deformation mechanisms of these\nphases are largely unknown including the active slip systems in most of these\ncomplex crystal structures. Here, we present a first detailed investigation of\nthe mechanical properties of the Fe7Mo6 {\\mu}-phase at room temperature using\nmicrocompression and nanoindentation with statistical EBSD-assisted slip trace\nanalysis and TEM imaging. Slip occurs predominantly on the basal and prismatic\nplanes, resulting also in decohesion on prismatic planes with high defect\ndensity. The correlation of the deformation structures and measured hardness\nreveals pronounced hardening where interaction of slip planes occurs and\nprevalent deformation at pre-existing defects."
    },
    {
        "anchor": "Pt/Ti/Al2O3/Al tunnel junctions showing electroforming-free bipolar\n  resistive switching behavior: We investigated electroforming-free bipolar resistive switching behavior in\nPt/Ti/Al2O3/Al tunnel junctions where the Al2O3 tunnel barrier was naturally\nformed on Al in air. Various compliance current values for the junction's set\nswitching successfully lead to various resistance values in its low resistance\nstate, suggesting the possibility for multi-level-operation. A mechanism for\nthe bipolar switching is qualitatively discussed in terms of the modulation of\nthe tunnel barrier by the reactive Ti layer on top of the barrier.",
        "positive": "Atomistic-Level Analysis of Nanoindentation-Induced Plasticity in\n  Arc--Melted NiFeCrCo Alloys: The role of stacking faults: Concentrated solid solution alloys (CSAs) have attracted attention for their\npromising properties; however, current manufacturing methods face challenges in\ncomplexity, high costs, and limited scalability, raising concerns about\nindustrial viability. The prevalent technique, arc melting, yields high-purity\nsamples with complex shapes. In this study, we explore nanoindentation tests at\nroom temperature where arc-melted samples exhibit larger grain sizes,\ndiminishing the effects of grain boundaries on the results. Motivated by these\nfindings, our investigation focuses on the atomistic-level exploration of\nplasticity mechanisms, specifically dislocation nucleation and propagation\nduring nanoindentation tests. The intricate chemistry of NiFeCrCo CSA\ninfluences pile-ups and slip traces, aiming to elucidate plastic deformation by\nconsidering both pristine and pre-existing stacking fault tetrahedra. Our\nanalysis scrutinizes dynamic deformation processes, defect nucleation, and\nevolution, complemented by stress-strain and dislocation densities-strain\ncurves illustrating the hardening mechanism of defective materials.\nAdditionally, we examine surface morphology and plastic deformation through\natomic shear strain and displacement mappings. This integrated approach\nprovides insights into the complex interplay between material structure and\nmechanical behavior, paving the way for an enhanced understanding and potential\nadvancements in CSA applications."
    },
    {
        "anchor": "Rapid multiphase-field model development using a modular free energy\n  based approach with automatic differentiation in MOOSE/MARMOT: We present a novel phase-field model development capability in the open\nsource MOOSE finite element framework. This facility is based on the 'modular\nfree energy' approach in which the phase-field equations are implemented in a\ngeneral form that is logically separated from model-specific data such as the\nthermodynamic free energy density and mobility functions. Free energy terms\ncontributing to a phase-field model are abstracted into self-contained objects\nthat can be dynamically combined at simulation run time. Combining multiple\nchemical and mechanical free energy contributions expedites the construction of\ncoupled phase-field, mechanics, and multiphase models. This approach allows\ncomputational material scientists to focus on implementing new material models,\nand to reuse existing solution algorithms and data processing routines. A key\nnew aspect of the rapid phase-field development approach that we discuss in\ndetail is the automatic symbolic differentiation capability. Automatic symbolic\ndifferentiation is used to compute derivatives of the free energy density\nfunctionals, and removes potential sources of human error while guaranteeing\nthat the nonlinear system Jacobians are accurately approximated. Through\njust-in-time compilation, we greatly reduce the computational expense of\nevaluating the differentiated expressions. The new capability is demonstrated\nfor a variety of representative applications.",
        "positive": "Defect propagation in one-, two-, and three-dimensional compounds doped\n  by magnetic atoms: Inelastic neutron scattering experiments were performed to study\nmanganese(II) dimer excitations in the diluted one-, two-, and\nthree-dimensional compounds CsMn(x)Mg(1-x)Br(3), K(2)Mn(x)Zn(1-x)F(4), and\nKMn(x)Zn(1-x)F(3) (x<0.10), respectively. The transitions from the ground-state\nsinglet to the excited triplet, split into a doublet and a singlet due to the\nsingle-ion anisotropy, exhibit remarkable fine structures. These unusual\nfeatures are attributed to local structural inhomogeneities induced by the\ndopant Mn atoms which act like lattice defects. Statistical models support the\ntheoretically predicted decay of atomic displacements according to 1/r**2, 1/r,\nand constant (for three-, two-, and one-dimensional compounds, respectively)\nwhere r denotes the distance of the displaced atoms from the defect. The\nobserved fine structures allow a direct determination of the local exchange\ninteractions J, and the local intradimer distances R can be derived through the\nlinear law dJ/dR."
    },
    {
        "anchor": "Grain boundary diffusion and grain boundary structures of a\n  Ni-Cr-Fe-alloy: Evidences for grain boundary phase transformations: Grain boundary tracer diffusion of Ni, Fe and Cr was studied in a Ni-base\n602CA coarse-grained alloy. A co-existence of several short-circuit\ncontributions was distinguished at higher temperatures in Harrison's B-type\nregime (773-873 K), which were related to different families of high-angle\ngrain boundaries with distinct coverages by precipitates and segregation levels\nas revealed by HAADF-STEM combined with EDX measurements. Annealing at 873 K\nfor 18 hours resulted in Cr23C6-type carbides coexisting with an\n\\alpha-Cr-Mn-enriched phase in addition to sequential segregation layers of Al,\nFe and Ni around them. Curved and hackly grain boundaries showed a high density\nof plate-like carbides, whereas straight grain boundaries were composed of\nglobular carbides with similar chemical composition variations and additionally\nwith alternating layers of Cr and Ni in between the carbides, similar to\nmicrostructures after a spinodal decomposition. At lower temperatures,\ndiscontinuous interfaces with Cr and Cr-carbide enrichment dominated and the\nalloy annealed at 403 K for 72 hours contained plate-like Cr23C6-type carbides\nsurrounded by a Ni-rich layer around them. The Ni grain boundary diffusion\nrates at these relatively low temperatures (formally belonging to C-type\nkinetics) showed an anomalous character being almost temperature independent.\nThis specific diffusion behaviour was explained by a concomitant relaxation of\ntransformation-induced elastic strains occurring on a longer time scale with\nrespect to grain boundary diffusion. Thermodynamic insights into the probable\nmechanism of decomposition at grain boundaries are provided.",
        "positive": "Islands in the Stream: Electromigration-Driven Shape Evolution with\n  Crystal Anisotropy: We consider the shape evolution of two-dimensional islands on a crystal\nsurface in the regime where mass transport is exclusively along the island\nedge. A directed mass current due to surface electromigration causes the island\nto migrate in the direction of the force. Stationary shapes in the presence of\nan anisotropic edge mobility can be computed analytically when the capillary\neffects of the line tension of the island edge are neglected, and conditions\nfor the existence of non-singular stationary shapes can be formulated. In\nparticular, we analyse the dependence of the direction of island migration on\nthe relative orientation of the electric field to the crystal anisotropy, and\nwe show that no stationary shapes exist when the number of symmetry axes is\nodd. The full problem including line tension is solved by time-dependent\nnumerical integration of the sharp-interface model. In addition to stationary\nshapes and shape instability leading to island breakup, we also find a regime\nwhere the shape displays periodic oscillations."
    },
    {
        "anchor": "A simple model for vacancy order and disorder in defective half-Heusler\n  systems: Defective half-Heusler systems X(1-x)YZ with large amounts of intrinsic\nvacancies, such as Nb(1-x)CoSb, Ti(1-x)NiSb and V(1-x)CoSb, are a group of\npromising thermoelectric materials. Even with high vacancy concentrations they\nmaintain the average half-Heusler crystal structure. These systems show high\nelectrical conductivity but low thermal conductivity arising from an ordered YZ\nlattice, which conducts electrons, while the large amounts of vacancies on the\nX sublattice effectively scatters phonons. Using electron scattering it was\nrecently observed that in addition to Bragg diffraction from the average cubic\nhalf-Heusler structure, some of these samples show broad diffuse scattering\nindicating short-range vacancy order while other samples show sharp additional\npeaks, indicating long-range vacancy ordering. Here we show that both the short\nand long-range ordering can be explained using the same simple model, which\nassumes that vacancies on the X-sublattice avoid each other. The samples\nshowing long-range vacancy order are in agreement with the predicted\nground-state of the model, while short-range order samples are quenched\nhigh-temperature states of the system. A previous study showed that changes in\nsample stoichiometry affect whether the short or long-range vacancy structure\nis obtained, but the present model suggests that thermal treatment of samples\nshould allow controlling the degree of vacancy order, and thereby the thermal\nconductivity, without changes in composition. This is important as the\ncomposition also dictates the amount of electrical carriers. Independent\ncontrol of electrical carrier concentration and degree of vacancy order should\nallow further improvements in the thermoelectric properties of these systems.",
        "positive": "Awaking of ferromagnetism in GaMnN through control of Mn valence: Room temperature ferromagnetism of GaMnN thin films is awaked by a mild\nhydrogenation treatment of samples synthesized by molecular beam epitaxy. Local\nenvironment of Mn atoms is monitored by Mn-L2,3 near edge x-ray absorption fine\nstructure (NEXAFS) technique. Doped Mn ions are present at substitutional sites\nof Ga both before and after the hydrogenation. No secondary phase can be\ndetected. Major valency of Mn changes from +3 to +2 by the hydrogenation. The\npresent result supports the model that the ferromagnetism occurs when Mn2+ and\nMn3+ are coexistent and holes in the mid- gap Mn band mediate the magnetic\ncoupling."
    },
    {
        "anchor": "Grain boundary relaxation and reconstruction: effect on local magnetic\n  moment: We present a detailed numerical study on structure and local magnetic\nproperties of $\\langle 100 \\rangle$ symmetric tilt grain boundaries in\nbcc-iron. Particular attention is paid to connection between type of grain\nboundary relaxation and local magnetic properties. Results from first\nprinciples calculation showed that grain boundary reconstruction leads to\nnon-uniform distribution of local magnetic moments in grain boundary plane.\nThis is in contrast with the result obtained in grain boundary plane, where\nsimple relaxation is observed. Well optimized atomic configurations in the\nvicinity of the interface were achieved by simulated annealing optimization\ntechnique improved by combination with genetic algorithm.",
        "positive": "Two-dimensional Penta-NiPS Sheets: Two Stable Polymorphs: The discovery of new and stable two-dimensional (2D) materials with exotic\nproperties is essential for technological advancement. Inspired by the recently\nreported penta-PdPSe, we proposed penta-NiPS as a new member of the penta-2D\nmaterials based on first-principles calculations. The penta-NiPS monolayer is\nstable in two polymorphs including the alpha phase with identical structure as\npenta-PdPSe, and the newly proposed beta phase with rotated sublayers.\nComprehensive analysis indicated that both phases are thermodynamically,\ndynamically, mechanically, and thermally stable. The penta-NiPS is a soft\nmaterial with 2D Young's modulus of Ea=208 Nm^-1 and Eb=187 Nm^-1 for the alpha\nphase and Ea=184 Nm^-1 and Eb=140 Nm^-1 for the beta phase. Interestingly, the\nalpha-penta-NiPS showed nearly zero Poisson's ratios along the in-plane\ndirection, where its dimensions would be maintained when being extended. For\nelectronic applications, we demonstrated that penta-NiPS is the wide band gap\nsemiconductor with an indirect band gap of 2.35 eV for alpha phase, and 2.20 eV\nfor beta phase."
    },
    {
        "anchor": "Dynamical Formation of Graphene and Graphane Nanoscrolls: Carbon nanoscrolls (CNSs) are nanomaterials with geometry resembling graphene\nlayers rolled up into a spiral (papyrus-like) form. Effects of hydrogenation\nand temperature on the self-scrolling process of two nanoribbons interacting\nwith a carbon nanotube (CNT) have been studied by molecular dynamics\nsimulations for three configurations: (1) graphene/graphene/CNT; (2)\ngraphene/graphane/CNT, and (3) graphane/graphane/CNT. Graphane refers to a\nfully hydrogenated graphene nanoribbon. Nanoscroll formation is observed for\nconfigurations (1) and (2) for temperatures 300-1000 K, while nanoribbons wrap\nCNT without nanoscroll formation for configuration (3).",
        "positive": "Theoretical Model Upper Limit on The Lattice Parameter of Doped C60\n  Solid: The results on the lattice instability, invoked by applying a negative\npressure on pure C60 solid, are described. The results of such a calculation\nare used to correlate the experimentally achieved results on the\nsuperconducting transition temperature Tc by doping C60 with alkali metals. A\nsimple model had been used already to interpret the bulk, structure and\nthermodynamic properties Of C60 solids. As a result of this calculation an\nupper limit on the lattice parameter results which is around 14.5A and is a\nsuggestion of an upper limit of Tc as well in doped C60."
    },
    {
        "anchor": "Thermodynamic theory of epitaxial ferroelectric thin films with dense\n  domain structures: A Landau-Ginsburg-Devonshire-type nonlinear phenomenological theory is\npresented, which enables the thermodynamic description of dense laminar\npolydomain states in epitaxial ferroelectric thin films. The theory explicitly\ntakes into account the mechanical substrate effect on the polarizations and\nlattice strains in dissimilar elastic domains (twins). Numerical calculations\nare performed for PbTiO3 and BaTiO3 films grown on (001)-oriented cubic\nsubstrates. The \"misfit strain-temperature\" phase diagrams are developed for\nthese films, showing stability ranges of various possible polydomain and\nsingle-domain states. Three types of polarization instabilities are revealed\nfor polydomain epitaxial ferroelectric films, which may lead to the formation\nof new polydomain states forbidden in bulk crystals. The total dielectric and\npiezoelectric small-signal responses of polydomain films are calculated,\nresulting from both the volume and domain-wall contributions. For BaTiO3 films,\nstrong dielectric anomalies are predicted at room temperature near special\nvalues of the misfit strain.",
        "positive": "Near-field light emission from nano- and micrometric complex structures: We propose a general theoretical scheme for the investigation of light\nemitted from nano- and micrometric structures of arbitrary shape and\ncomposition. More specifically, the proposed fully three-dimensional approach\nallows to derive the light-intensity distributions around the emitting\nstructures and their modifications in the presence of nearby scattering\nobjects. Our analysis allows to better identify the non-trivial relationship\nbetween near-field images and fluorescent objects."
    },
    {
        "anchor": "Non-perturbative theory of the electron-phonon coupling and its\n  first-principles implementation: The harmonic approximation of ionic fluctuations and the linear coupling\nbetween phonons and electrons provide the basic approach to compute, from first\nprinciples, the contribution that the nuclei dynamics and its interaction with\nelectrons have on materials' properties. These approaches are questionable, at\nleast, whenever quantum and anharmonic effects on the nuclei vibrational\nproperties are large, such as in hydrogenous systems, high-$T_c$\nsuperconductors, and when systems are close to displacive phase transitions.\nHere we propose a novel non-perturbative approach to compute the\nelectron-phonon interaction from first principles that includes non-linear\neffects and takes into account the quantum nature of nuclei. The method is\nbased on the $GW^{(en)}$ approximation for the electron self-energy, given by\nthe effective nuclei-mediated electron-electron interaction $W^{(en)}$ and the\nelectron Green's function $G$. The electrons are treated at a mean-field level\nand the nuclei dynamics is described with a Gaussian distribution function,\nwhich can effectively take into account anharmonic effects at a mean-field\nlevel, e.g. within the self-consistent harmonic approximation. Pivotal\nquantities of the Gaussian $GW^{(en)}$ self-energy are the renormalized average\nvertices, which are computed in supercells with a stochastic approach, using\nthe the self-consistent electronic potential computed for different atomic\nconfigurations. In order to validate the method, $GW^{(en)}$ calculations are\nperformed on aluminum, a highly harmonic system with weak electron-phonon\ncoupling. The obtained results coincide with the ones obtained with standard\nlinear electron-phonon calculations. However, calculations performed on\npalladium hydride, a very anharmonic system, show a highly non-linear\nelectron-phonon interaction, with $GW^{(en)}$ bringing corrections as high as\nthe linear-order result.",
        "positive": "Topological Crystalline Insulator Nanostructures: Topological crystalline insulators are topological insulators whose surface\nstates are protected by the crystalline symmetry, instead of the time reversal\nsymmetry. Similar to the first generation of three-dimensional topological\ninsulators such as Bi2Se3 and Bi2Te3, topological crystalline insulators also\npossess surface states with exotic electronic properties such as spin-momentum\nlocking and Dirac dispersion. Experimentally verified topological crystalline\ninsulators to date are SnTe, Pb1-xSnxSe, and Pb1-xSnxTe. Because topological\nprotection comes from the crystal symmetry, magnetic impurities or in-plane\nmagnetic fields are not expected to open a gap in the surface states in\ntopological crystalline insulators. Additionally, because they are cubic\nstructure instead of layered structure, branched structures or strong coupling\nwith other materials for large proximity effects are possible, which are\ndifficult with layered Bi2Se3 and Bi2Te3. Thus, additional fundamental\nphenomena inaccessible in three-dimensional topological insulators can be\npursued. In this review, topological crystalline insulator SnTe nanostructures\nwill be discussed. For comparison, experimental results based on SnTe thin\nfilms will be covered. Surface state properties of topological crystalline\ninsulators will be discussed briefly."
    },
    {
        "anchor": "Re-understanding of the deformation potential constant in the single\n  crystal silicon: The mobility formula based on deformation potential (DP) theory is of great\nimportance in semiconductor physics. However, the related calculations for the\nDP constant are controversial. It is necessary to redo in-depth and\ncomprehensive research on the mobility of single crystal silicon and the\nrelated parameters such as the effective mass and the DP constant. In this work\nthe conductivity effective mass is redefined and a method based on the first\nprinciples is presented to evaluate the correction of the DP constant. It is\nfound that the effective mass is closer to experimental data and the correction\nof the DP is a negligible value of about 0.3 eV. Using these parameters, we\nobtain the mobilities of the single crystal silicon in reasonable agreement\nwith the experimental values. Our method can be effectively applied to the\nprediction for the mobility in bulk materials.",
        "positive": "Temperature Dependence of the Spin Resistivity in Ferromagnetic Thin\n  Films: The magnetic phase transition is experimentally known to give rise to an\nanomalous temperature-dependence of the electron resistivity in ferromagnetic\ncrystals. Phenomenological theories based on the interaction between itinerant\nelectron spins and lattice spins have been suggested to explain these\nobservations. In this paper, we show by extensive Monte Carlo (MC) simulation\nthe behavior of the resistivity of the spin current calculated as a function of\ntemperature ($T$) from low-$T$ ordered phase to high-$T$ paramagnetic phase in\na ferromagnetic film. We analyze in particular effects of film thickness,\nsurface interactions and different kinds of impurities on the spin resistivity\nacross the critical region. The origin of the resistivity peak near the phase\ntransition is shown to stem from the existence of magnetic domains in the\ncritical region. We also formulate in this paper a theory based on the\nBoltzmann's equation in the relaxation-time approximation. This equation can be\nsolved using numerical data obtained by our simulations. We show that our\ntheory is in a good agreement with our MC results. Comparison with experiments\nis discussed."
    },
    {
        "anchor": "Physics-based Modeling of Pulse and Relaxation of High-rate\n  Li/CF$_{x}$-SVO batteries in Implantable Medical Devices: We present a physics-based model that accurately predicts the performance of\nMedtronic's implantable medical device battery lithium/carbon monofluoride\n(CF$_x$) - silver vanadium oxide (SVO) under both low-rate background\nmonitoring and high-rate pulsing currents. The distinct properties of multiple\nactive materials are reflected by parameterizing their thermodynamics,\nkinetics, and mass transport properties separately. Diffusion limitations of\nLi$^+$ in SVO are used to explain cell voltage transient behavior during pulse\nand post-pulse relaxation. We also introduce change in cathode electronic\nconductivity, Li metal anode surface morphology, and film resistance buildup to\ncapture evolution of cell internal resistance throughout multi-year electrical\ntests. We share our insights on how the Li$^+$ redistribution process between\nactive materials can restore pulse capability of the hybrid electrode, allow\nCF$_x$ to indirectly contribute to capacity release during pulsing, and affect\nthe operation protocols and design principles of batteries with other hybrid\nelectrodes. We also discuss additional complexities in porous electrode model\nparameterization and electrochemical characterization techniques due to\nparallel reactions and solid diffusion pathways across active materials. We\nhope our models implemented in the Hybrid Multiphase Porous Electrode Theory\n(Hybrid-MPET) framework can complement future experimental research and\naccelerate development of multi-active material electrodes with targeted\nperformance.",
        "positive": "Mechanical and Electronic Properties of MoS$_2$ Nanoribbons and Their\n  Defects: We present our study on atomic, electronic, magnetic and phonon properties of\none dimensional honeycomb structure of molybdenum disulfide (MoS$_2$) using\nfirst-principles plane wave method. Calculated phonon frequencies of bare\narmchair nanoribbon reveal the fourth acoustic branch and indicate the\nstability. Force constant and in-plane stiffness calculated in the harmonic\nelastic deformation range signify that the MoS$_2$ nanoribbons are stiff quasi\none dimensional structures, but not as strong as graphene and BN nanoribbons.\nBare MoS$_2$ armchair nanoribbons are nonmagnetic, direct band gap\nsemiconductors. Bare zigzag MoS$_2$ nanoribbons become half-metallic as a\nresult of the (2x1) reconstruction of edge atoms and are semiconductor for\nminority spins, but metallic for the majority spins. Their magnetic moments and\nspin-polarizations at the Fermi level are reduced as a result of the\npassivation of edge atoms by hydrogen. The functionalization of MoS$_2$\nnanoribbons by adatom adsorption and vacancy defect creation are also studied.\nThe nonmagnetic armchair nanoribbons attain net magnetic moment depending on\nwhere the foreign atoms are adsorbed and what kind of vacancy defect is\ncreated. The magnetization of zigzag nanoribbons due to the edge states is\nsuppressed in the presence of vacancy defects."
    },
    {
        "anchor": "Molecular-level understanding of the WGS and reverse WGS reactions on Rh\n  through hierarchical multiscale approach: Hierarchically combining semi-empirical methods and first-principles\ncalculations we gain a novel and noteworthy picture of the molecular-level\nmechanisms that govern the water-gas-shift (WGS) and reverse water-gas-shift\n(r-WGS) reactions on Rh catalysts. Central to this picture is that the WGS and\nr-WGS follow two different dominant reaction mechanisms: WGS proceeds according\nto a carboxyl (COOH) mechanism, whereas r-WGS proceeds according to a redox\n(CO2 {\\to} CO + O) mechanism. The obtained results furthermore underscore the\ndanger of common first-principles analyses that focus on a priori selected\ndominant paths. Not restricted to such bias, our herein proposed hierarchical\napproach thus constitutes a promising avenue to properly transport and\nincorporate the ab initio predictive-quality to a new level of system\ncomplexity.",
        "positive": "Unified continuum approach to crystal surface morphological relaxation: A continuum theory is used to predict scaling laws for the morphological\nrelaxation of crystal surfaces in two independent space dimensions. The goal is\nto unify previously disconnected experimental observations of decaying surface\nprofiles. The continuum description is derived from the motion of interacting\natomic steps. For isotropic diffusion of adatoms across each terrace, induced\nadatom fluxes transverse and parallel to step edges obey different laws,\nyielding a tensor mobility for the continuum surface flux. The partial\ndifferential equation (PDE) for the height profile expresses an interplay of\nstep energetics and kinetics, and aspect ratio of surface topography that\nplausibly unifies observations of decaying bidirectional surface corrugations.\nThe PDE reduces to known evolution equations for axisymmetric mounds and\none-dimensional periodic corrugations."
    },
    {
        "anchor": "Charge-sensitive vibrational modes in the (EDT-TTF-OX)_2AsF_6 chiral\n  molecular conductors: Infrared and Raman spectra of the three chiral molecular conductors\n(EDT-TTF-OX)_2AsF_6, comprising two salts based on enantiopure EDT-TTF-OX donor\nmolecules and one based on their racemic mixture, have been measured as a\nfunction of temperature. In the frequency range of the C=C stretching\nvibrations of EDT-TTF-OX, charge-sensitive modes are identified based on\ntheoretical calculations for neutral and oxidized EDT-TTF-OX using density\nfunctional theory (DFT) methods. The positions of the C=C stretching modes in\nboth Raman and infrared spectra of the (EDT-TTF-OX)_2AsF_6 materials are\nanalyzed assuming linear relationship between the frequency and charge on the\nmolecule. The charge density on the EDT-TTF-OX donor molecule is estimated to\nbe +0.5 in all the investigated materials and does not change with temperature.\nTherefore it is suggested, that M-I transition observed in (EDT-TTF-X)_2AsF_6\nchiral molecular conductors at low temperature is not related to the charge\nordering mechanism.",
        "positive": "Enhancement in Li-ion Conductivity through Co-doping of Ge and Ta in\n  Garnet Li$_7$La$_3$Zr$_2$O$_{12}$ Solid Electrolyte: For being used as an electrolyte in All Solid State Batteries (ASSB), a solid\nelectrolyte must possess ionic conductivity comparable to that of conventional\nliquid electrolytes. To achieve this conductivity range, the series\nLi$_{6.8-y}$Ge$_{0.05}$La$_3$Zr$_{2-y}$Ta$_y$O$_{12}$ ($y = 0, 0.15, 0.25,\n0.35, 0.45$) has been synthesized using solid-state reaction method and studied\nusing various characterization techniques. The highly conducting cubic phase is\nconfirmed from XRD analysis. Structural information was collected using SEM and\ndensity measurements. The prepared ceramic sample containing 0.25 Ta, sintered\nat 1050$^\\circ$C for 7.30 hrs shows the maximum ionic conductivity of 6.61 x\n10$^{-4}$ S/cm at 25$^\\circ$C. The air stability of the same ceramic has also\nbeen evaluated after exposure for 5 months. The minimum activation energy\nassociated with the maximum conductivity of 0.25 Ta is 0.25 eV. The DC\nconductivity measurements were done to confirm the ionic nature of conductivity\nfor all ceramic samples. The stable result of ionic conductivity makes the 0.25\nTa containing ceramic sample a promising candidate for solid electrolytes for\nASSB applications."
    },
    {
        "anchor": "Elastic Properties and Glass Forming Ability of the\n  Zr$_{50}$Cu$_{40}$Ag$_{10}$ Metallic Alloy: The elastic properties of the Zr$_{50}$Cu$_{40}$Ag$_{10}$ metallic alloy,\nsuch as the bulk modulus $B$, the shear modulus $G$, the Young's modulus $E$\nand the Poisson's ratio $\\sigma$, are investigated by molecular dynamics\nsimulation in the temperature range $T=250-2000$ K and at an external pressure\nof $p = 1.0$ bar. It is shown that the liquid-glass transition is accompanied\nby a considerable increase in the shear modulus $G$ and the Young's modulus $E$\n(by more than $50\\%$). The temperature dependence of the Poisson's ratio\nexhibits a sharp fall from typical values for metals of approximately\n$0.32-0.33$ to low values (close to zero), which are characteristic for brittle\nbulk metallic glasses. Non-monotonic temperature dependence of the longitudinal\nand transverse sound velocity near the liquid-glass transition is also\nobserved. The glass forming ability of the alloy is evaluated in terms of the\nfragility index $m$. As found, its value is $m\\approx64$ for the\nZr$_{50}$Cu$_{40}$Ag$_{10}$ metallic glass, that is in a good agreement with\nthe experimental data for the Zr-Cu-based metallic glasses.",
        "positive": "Localization Analysis of an Energy-Based Fourth-Order Gradient\n  Plasticity Model: The purpose of this paper is to provide analytical and numerical solutions of\nthe formation and evolution of the localized plastic zone in a uniaxially\nloaded bar with variable cross-sectional area. An energy-based variational\napproach is employed and the governing equations with appropriate physical\nboundary conditions, jump conditions, and regularity conditions at evolving\nelasto-plastic interface are derived for a fourth-order explicit gradient\nplasticity model with linear isotropic softening. Four examples that differ by\nregularity of the yield stress and stress distributions are presented. Results\nfor the load level, size of the plastic zone, distribution of plastic strain\nand its spatial derivatives, plastic elongation, and energy balance are\nconstructed and compared to another, previously discussed non-variational\ngradient formulation."
    },
    {
        "anchor": "Na-catalyzed rapid synthesis and characterization of intercalated\n  graphite CaC6: In this study, we conducted experiments on CaC6 for elucidating the\nNa-catalyzed formation mechanism and achieving rapid mass synthesis of graphite\nintercalation compounds (GICs). Rapidly synthesized CaC6 was characterized by\nanalysis of its crystal structure and physical properties. We found that the\nformation of the reaction intermediate Na-GIC (NaCx, x = 64) requires a larger\namount of Na than is intercalated between the graphite interlayers. The\nrequirement for excess Na may provide insights into the mechanism of\nNa-catalyzed GIC formation. A Na-to-C molar mixing ratio of 1.5-2.0:6 was\nsuitable for the efficient formation of CaC6 under heat treatment at 250{\\deg}C\nfor 2 h, and the catalytic Na remaining in the sample was demonstrably reduced\nto a Na:Ca ratio of approximately 3:97. The upper critical field Hc2 was\nenhanced approximately three times compared to those of previous reports. Based\non X-ray diffraction and experimental parameter analysis, we concluded that the\nenhancement of Hc2 was attributed to the disordered stacking sequence in CaC6,\npossibly because of the rapid and low-temperature formation. Physical\nproperties derived from specific heat measurements were comparable to those of\nhigh-quality CaC6, which is slowly synthesized using the molten Li-Ca alloy\nmethod. This study provides new avenues for future research and exploration in\nthe rapid mass synthesis of GICs as practical materials, for applications such\nas battery electrodes and superconducting wires.",
        "positive": "A low temperature disordered phase of alpha-Pb/Ge(111): A new structural phase transition has been observed at low temperatures for\nthe one third of a monolayer (alpha phase) of Pb on Ge(111) using a\nvariable-temperature scanning tunneling microscope. The well-known (r3xr3)R30\nto (3x3) transition is accompanied by a new structural phase transition from\n(3x3) to a disordered phase at ~76 K. The formation of the new disordered phase\nis incompatible with the belief that the (3x3) phase is the ground state. The\nmechanism of the phase transition in this triangular lattice can be mapped onto\nantiferromagnetic spin Ising model, with the geometric frustration."
    },
    {
        "anchor": "Reply to \"Comment on 'Theory for tailoring sonic devices: Diffraction\n  dominates over refraction' \": In their comment, A. Hakansson, J. Sanchez-Dehesa, F. Cervera, F. Meseguer,\nL. Sanchis, and J. Llinares say that our conclusion stating that diffraction\nprevails over refraction in acoustic lenses whose aperture is of several\nwavelengths, such as those addressed in our calculations [N. Garcia, M.\nNieto-Vesperinas, E. V. Ponizovskaya, and M.Torres, Phys. Rev. E 67, 046606\n(2003)] and in their experiments [F.Cervera, L. Sanchis, J. V. Sanchez-Perez,\nR. Martinez-Sala, C. Rubio, F.Meseguer, C. Lopez, D. Caballero, and J.\nSanchez-Dehesa, Phys. Rev. Lett.88, 023902 (2003)], is misleading because the\nsize of their lenses is larger than ours. They state that diffraction effects\nare negligible at the scale of their experiments. In this reply we calculate\nthe propagation of a plane wave through both a lens and a slab of aluminum\ncylinders, identical to those presented by such authors in previous\nexperiments, by using a finite difference time domain (FDTD) method. We then\ncompare our results to the experiments previously reported by the authors of\nthe comment and significant differences are found. Our present calculations\nshow that refraction and diffraction are intrinsically interwoven also at the\nscale of their experiments.",
        "positive": "Irreversible Temperature Quenching and Antiquenching of\n  Photoluminescence of ZnS/CdS:Mn/ZnS Quantum Well Quantum Dots: An experimental observation on irreversible thermal quenching and\nantiquenching behavior is reported for photoluminescence (PL) of ZnS/CdS:Mn/ZnS\nquantum well quantum dots (QWQDs) prepared with a reverse micelle method. The\ndual-color emissions, a blue emission band centered at 430 nm and a Mn2+ 4T1 ->\n6A1 orange emission peak at 600 nm, were found to have different dependences of\nemission intensity on temperature in the range of 8-290 K. Depending on Mn2+\ndoping concentration, they can both show strong antiquenching behavior in a\ncertain temperature range in addition to the usual thermal quenching when\nlowering down temperature while it is very prominent for orange emission but\nweaker for blue emission. Moreover, the antiquenching behavior is weakened with\nrise of temperature, giving rise to a hysteretic PL temperature dependence for\nthe QWQDs."
    },
    {
        "anchor": "Lateral Signals in Piezoresponse Force Microscopy at Domain Boundaries\n  of Ferroelectric Crystals: In piezoresponse force microscopy a lateral signal at the domain boundaries\nis occasionally observed. In recent years, a couple of experiments have been\nreported and varying explanations for the origin of this lateral signal have\nbeen proposed. Additionally, elaborated theoretical modeling for this\nparticular issue has been carried out. Here we present experimental data\nobtained on different crystallographic cuts of $\\rm LiNbO_3$, $\\rm BaTiO_3$,\nand $\\rm KTiOPO_4$ single crystals. We could thereby rule out some of the\nexplanations proposed so far, introduce another possible mechanism, and\nquantitatively compare our results to the existing modeling.",
        "positive": "Paramagnetic resonance in La2NiMnO6 probed by impedance and lock-in\n  detection techniques: We report the detection of paramagnetic resonance in the double perovskite\nLa2NiMnO6 at room temperature for microwave magnetic fields with frequencies, f\n= 1 GHz to 5 GHz, using two cavity-less methods. We use an indirect impedance\nmethod which makes use of a radio frequency impedance analyzer and a folded\ncopper strip coil for the frequency range f = 1 to 2.2 GHz. In this method,\nwhen an applied dc magnetic field is swept, high-frequency resistance of the\nstrip coil exhibits a sharp peak and the reactance curve crosses zero\nexhibiting resonance. A lock-in based broadband setup using a coplanar\nwaveguide for microwave excitation was used for f = 2 to 5 GHz The resonance\nfields (Hr) obtained from both the techniques increase linearly with frequency\nand a large spectroscopic g-factor, equal to 2.1284, which supports the\npresence of Ni2+ cation with strong spin-orbit coupling. Line shape analysis\nand analytical fitting were performed to characterize the material in terms of\nits initial susceptibility and damping parameters."
    },
    {
        "anchor": "Tunable Conductivity and Conduction Mechanism in a UV light activated\n  electronic conductor: A tunable conductivity has been achieved by controllable substitution of a\nnovel UV light activated electronic conductor. The transparent conducting oxide\nsystem H-doped Ca12-xMgxAl14O33 (x = 0; 0.1; 0.3; 0.5; 0.8; 1.0) presents a\nconductivity that is strongly dependent on the substitution level and\ntemperature. Four-point dc-conductivity decreases with x from 0.26 S/cm (x = 0)\nto 0.106 S/cm (x = 1) at room temperature. At each composition the conductivity\nincreases (reversibly with temperature) until a decomposition temperature is\nreached; above this value, the conductivity drops dramatically due to hydrogen\nrecombination and loss. The observed conductivity behavior is consistent with\nthe predictions of our first principles density functional calculations for the\nMg-substituted system with x=0, 1 and 2. The Seebeck coefficient is essentially\ncomposition- and temperature-independent, the later suggesting the existence of\nan activated mobility associated with small polaron conduction. The optical gap\nmeasured remains constant near 2.6 eV while transparency increases with the\nsubstitution level, concomitant with a decrease in carrier content.",
        "positive": "Impact of surface phenomena on direct bulk flexoelectric effect in\n  finite samples: In the framework of a continuum theory, it is shown that the direct\nflexoelectric response of a finite sample essentially depends on the surface\npolarization energy, even in the thermodynamic limit where the body size tends\nto infinity. It is found that a modification of the surface energy can lead to\na change of the polarization response by a factor of two. The origin of the\neffect is an electric field produced by surface dipoles induced by the strain\ngradient. The unexpected sensitivity of the polarization response to the\nsurface energy in the thermodynamic limit is conditioned by the fact that the\nmoments of the surface dipoles may scale as the body size."
    },
    {
        "anchor": "Nonlinear spectroscopy with entangled photons; manipulating quantum\n  pathways of matter: Optical signals obtained by the material response to classical laser fields\nare given by nonlinear response functions which can be expressed by sums over\nvarious quantum pathways of matter. We show that some pathways can be selected\nby using nonclassical fields, through the entanglement of photon and material\npathways, which results in a different-power law dependence on the incoming\nfield intensity. Spectrally overlapping stimulated Raman scattering (SRS) and\ntwo-photon-absorption (TPA) pathways in a pump probe experiment are separated\nby controlling the degree of entanglement of pairs of incoming photons.\nPathway-selectivity opens up new avenues for mapping photon into material\nentanglement. New material information, otherwise erased by interferences among\npathways, is revealed.",
        "positive": "Structural and magneto-transport characterization of Co_2Cr_xFe_(1-x)Al\n  Heusler alloy films: We investigate the structure and magneto-transport properties of thin films\nof the Co_2Cr_xFe_(1-x)Al full-Heusler compound, which is predicted to be a\nhalf-metal by first-principles theoretical calculations. Thin films are\ndeposited by magnetron sputtering at room temperature on various substrates in\norder to tune the growth from polycrystalline on thermally oxidized Si\nsubstrates to highly textured and even epitaxial on MgO(001) substrates,\nrespectively. Our Heusler films are magnetically very soft and ferromagnetic\nwith Curie temperatures up to 630 K. The total magnetic moment is reduced\ncompared to the theoretical bulk value, but still comparable to values reported\nfor films grown at elevated temperature. Polycrystalline Heusler films combined\nwith MgO barriers are incorporated into magnetic tunnel junctions and yield 37%\nmagnetoresistance at room temperature."
    },
    {
        "anchor": "Mechanisms and origin of multiferroicity: Motivated by the potential applications of their intrinsic cross-coupling\nproperties, the interest in multiferroic materials has constantly increased\nrecently, leading to significant experimental and theoretical advancements.\nFrom the theoretical point of view, recent progresses have allowed to identify\ndifferent mechanisms responsible for the appearence of ferroelectric\npolarization coexisting with -- and coupled to -- magnetic properties. This\nchapter aims at reviewing the fundamental mechanisms devised so far, mainly in\ntransition-metal oxides, which lie at the origin of multiferroicity.",
        "positive": "1D van der Waals Material Tellurium: Raman Spectroscopy under Strain and\n  Magneto-transport: Experimental demonstrations of 1D van der Waals material tellurium have been\npresented by Raman spectroscopy under strain and magneto-transport. Raman\nspectroscopy measurements have been performed under strains along different\nprinciple axes. Pronounced strain response along c-axis is observed due to the\nstrong intra-chain covalent bonds, while no strain response is obtained along\na-axis due to the weak inter-chain van der Waals interaction. Magneto-transport\nresults further verify its anisotropic property, resulting in dramatically\ndistinct magneto-resistance behaviors in terms of three different magnetic\nfield directions. Specifically, phase coherence length extracted from weak\nantilocalization effect, L$_{\\Phi}$ ~ T$^{-0.5}$, claims its 2D transport\ncharacteristics when an applied magnetic field is perpendicular to the thin\nfilm. In contrast, L$_{\\Phi}$ ~ T$^{-0.33}$ is obtained from universal\nconductance fluctuations once the magnetic field is along c-axis of Te,\nindicating its nature of 1D transport along the helical atomic chains. Our\nstudies, which are obtained on high quality single crystal tellurium thin film,\nappear to serve as strong evidences of its 1D van der Waals structure from\nexperimental perspectives. It is the aim of this paper to address this special\nconcept that differs from the previous well-studied 1D nanowires or 2D van der\nWaals materials."
    },
    {
        "anchor": "A Novel Mechanism for the Formation of Dislocation Cell Patterns in BCC\n  Metal: In this study, we present the first simulation results of the formation of\ndislocation cell wall microstructures in tantalum subjected to shock loading.\nDislocation patterns and cell wall formation are important to understanding the\nmechanical properties of the materials in which they spontaneously arise, and\nyet the processing and self-assembly mechanisms leading to their formation are\npoorly understood. By employing transmission electron microscopy and discrete\ndislocation dynamics, we propose a new mechanism involving coplanar\ndislocations and pseudo-dipole mixed dislocation arrays that is essential to\nthe pattern formation process. Our large-scale 3D DDD simulations demonstrate\nthe self-organization of dislocation networks into cell walls in deformed BCC\nmetal (tantalum) persisting at the strain 20%. The simulation analysis captures\nseveral crucial aspects of how the dislocation cell pattern affects metal\nplasticity, as observed in experiments. Although experimental evidence is\ninconclusive regarding whether cell wall formation takes place at the shock\nfront, after the shock, during release, or when the sample has had enough time\nto relax post-recovery, our simulations indicate cell wall formation occurs\nafter the shock and before release. The extended Taylor hardening composite\nmodel effectively considers the non-uniform dislocation density when cell walls\nform and accurately describes the corresponding flow stress.",
        "positive": "Quantum dot size dependent influence of the substrate orientation on the\n  electronic and optical properties of InAs/GaAs quantum dots: Using 3D k.p calculation including strain and piezoelectricity we predict\nvariation of electronic and optical properties of InAs/GaAs quantum dots (QDs)\nwith the substrate orientation. The QD transition energies are obtained for\nhigh index substrates [11k], where k = 1,2,3 and are compared with [001]. We\nfind that the QD size in the growth direction determines the degree of\ninfluence of the substrate orientation: the flatter the dots, the larger the\ndifference from the reference [001] case."
    },
    {
        "anchor": "Nonlinear magnetoinductive waves and domain walls in composite\n  metamaterials: We describe novel physics of nonlinear magnetoinductive waves in left-handed\ncomposite metamaterials. We derive the coupled equations for describing the\npropagation of magnetoinductive waves, and show that in the nonlinear regime\nthe magnetic response of a metamaterial may become bistable. We analyze\nmodulational instability of different nonlinear states, and also demonstrate\nthat nonlinear metamaterials may support the propagation of domain walls\n(kinks) connecting the regions with the positive and negative magnetization.",
        "positive": "Magnetic interaction at an interface between manganite and other\n  transition metal oxides: A general consideration is presented for the magnetic interaction at an\ninterface between a perovskite manganite and other transition metal oxides. The\nlatter is specified by the electron number $n$ in the $d_{3z^2-r^2}$ level as\n$(d_{3z^2-r^2})^n$. Based on the molecular orbitals formed at the interface and\nthe generalized Hund's rule, the sign of the magnetic interaction is rather\nuniquely determined. The exception is when the $d_{3z^2-r^2}$ orbital is\nstabilized in the interfacial manganite layer neighboring to a\n$(d_{3z^2-r^2})^1$ or $(d_{3z^2-r^2})^2$ system. In this case, the magnetic\ninteraction is sensitive to the occupancy of the Mn $d_{3z^2-r2}$ orbital. It\nis also shown that the magnetic interaction between the interfacial Mn layer\nand the bulk region can be changed. Manganite-based heterostructures thus show\na rich magnetic behavior. We also present how to generalize the argument\nincluding $t_{2g}$ orbitals."
    },
    {
        "anchor": "Wave propagation in single column woodpile phononic crystals: Formation\n  of tunable band gaps: We study the formation of frequency band gaps in single column woodpile\nphononic crystals composed of orthogonally stacked slender cylinders. We focus\non investigating the effect of the cylinders local vibrations on the dispersion\nof elastic waves along the stacking direction of the woodpile phononic\ncrystals. We experimentally verify that their frequency band structures depend\nsignificantly on the bending resonant behavior of unit cells. We propose a\nsimple theoretical model based on a discrete element method to associate the\nbehavior of locally resonant cylindrical rods with the band gap formation\nmechanism in woodpile phononic crystals. The findings in this work imply that\nwe can achieve versatile control of frequency band structures in phononic\ncrystals by using woodpile architectures. The woodpile phononic crystals can\nform a new type of vibration filtering devices that offer an enhanced degree of\nfreedom in manipulating stress wave propagation.",
        "positive": "Detection mechanism in highly sensitive ZnO nanowires network gas\n  sensors: Metal-oxide nanowires are showing a great interest in the domain of gas\nsensing due to their large response even at a low temperature, enabling\nlow-power gas sensors. However their response is still not fully understood,\nand mainly restricted to the linear response regime, which limits the design of\nappropriate sensors for specific applications. Here we analyse the non-linear\nresponse of a sensor based on ZnO nanowires network, both as a function of the\ndevice geometry and as a response to oxygen exposure. Using an appropriate\nmodel, we disentangle the contribution of the nanowire resistance and of the\njunctions between nanowires in the network. The applied model shows a very good\nconsistency with the experimental data, allowing us to demonstrate that the\nresponse to oxygen at room temperature is dominated by the barrier potential at\nlow bias voltage, and that the nanowire resistance starts to play a role at\nhigher bias voltage. This analysis allows us to find the appropriate device\ngeometry and working point in order to optimize the sensitivity. Such analysis\nis important for providing design rules, not only for sensing devices, but also\nfor applications in electronics and opto-electronics using nanostructures\nnetworks with different materials and geometries."
    },
    {
        "anchor": "Inelastic electron tunneling spectroscopy of local \"spin accumulation\"\n  devices: We investigate the origin of purported \"spin accumulation\" signals observed\nin local \"three-terminal\" (3T) measurements of ferromagnet/insulator/n-Si\ntunnel junctions using inelastic electron tunneling spectroscopy (IETS).\nVoltage bias and magnetic field dependences of the IET spectra were found to\naccount for the dominant contribution to 3T magnetoresistance signals, thus\nindicating that it arises from inelastic tunneling through impurities and\ndefects at junction interfaces and within the barrier, rather than from spin\naccumulation due to pure elastic tunneling into bulk Si as has been previously\nassumed.",
        "positive": "Nucleation of a stable solid from melt in the presence of multiple\n  metastable intermediate phases: Wetting, Ostwald step rule and vanishing\n  polymorphs: In many systems, nucleation of a stable solid may occur in the presence of\nother (often more than one) metastable phases. These may be polymorphic solids\nor even liquid phases. In such cases, nucleation of the solid phase from the\nmelt may be facilitated by the metastable phase because the latter can \"wet\"\nthe interface between the parent and the daughter phases, even though there may\nbe no signature of the existence of metastable phase in the thermodynamic\nproperties of the parent liquid and the stable solid phase. Straightforward\napplication of classical nucleation theory (CNT) is flawed here as it\noverestimates the nucleation barrier since surface tension is overestimated (by\nneglecting the metastable phases of intermediate order) while the thermodynamic\nfree energy gap between daughter and parent phases remains unchanged. In this\nwork we discuss a density functional theory (DFT) based statistical mechanical\napproach to explore and quantify such facilitation. We construct a simple order\nparameter dependent free energy surface that we then use in DFT to calculate\n(i) the order parameter profile, (ii) the overall nucleation free energy\nbarrier and (iii) the surface tension between the parent liquid and the\nmetastable solid and also parent liquid and stable solid phases. The theory\nindeed finds that the nucleation free energy barrier can decrease significantly\nin the presence of wetting. This approach can provide a microscopic explanation\nof Ostwald step rule and the well-known phenomenon of \"disappearing polymorphs\"\nthat depends on temperature and other thermodynamic conditions. Theory reveals\na diverse scenario for phase transformation kinetics some of which may be\nexplored via modern nanoscopic synthetic methods."
    },
    {
        "anchor": "Orbital Selectivity in Hund's metals: The Iron Chalcogenides: We show that electron correlations lead to a bad metallic state in\nchalcogenides FeSe and FeTe despite the intermediate value of the Hubbard\nrepulsion $U$ and Hund's rule coupling $J$. The evolution of the quasi particle\nweight $Z$ as a function of the interaction terms reveals a clear crossover at\n$U \\simeq$ 2.5 eV. In the weak coupling limit $Z$ decreases for all correlated\n$d$ orbitals as a function of $U$ and beyond the crossover coupling they become\nweakly dependent on $U$ while strongly depend on $J$. A marked orbital\ndependence of the $Z$'s emerges even if in general the orbital-selective Mott\ntransition only occurs for relatively large values of $U$. This two-stage\nreduction of the quasi particle coherence due to the combined effect of Hubbard\n$U$ and the Hund's $J$, suggests that the iron-based superconductors can be\nreferred to as Hund's correlated metals.",
        "positive": "Technological guidelines for the design of tandem III-V nanowire on Si\n  solar cells from opto-electrical simulations: Effect of geometrical and structural parameters on the efficiency of the\ntandem solar cell based on the III-V nanowire array on silicon is studied by\nthe means of coupled opto-electrical simulations. A close to realistic\nstructure, consisting of AlGaAs core-shell nanowire array, connected through a\ntunnel diode to a Si subcell is modelled, revealing the impact of top contact\nlayer, growth mask and tunnel junction. Optical simulation of the tandem\nstructure under current matching condition determine optimal geometrical\nparameters of the nanowire array. They are then used in the extensive\nelectrical optimization of the radial junction in the nanowire subcell. Device\nsimulations show the necessity of high doping of the junction in order to avoid\nfull shell depletion. The influence of bulk and surface recombination on the\nperformance of the top subcell is studied, exposing the importance of the good\nsurface passivation near the depleted region of the radial p - n junction.\nFinally, simulations of the fully optimized tandem structure show that a\npromising efficiency of 27.6% with the short-circuit current density of 17.1\nmA/cm^2 can be achieved with reasonable bulk and surface carrier lifetime."
    },
    {
        "anchor": "Hydrocarbons under pressure: phase diagrams and surprising new compounds\n  in the C-H system: Understanding the high-pressure behavior of C-H system is of great importance\ndue to its key role in organic, bio-, petroleum and planetary chemistry. We\nhave performed a systematic investigation of the pressure-composition phase\ndiagram of the C-H system at pressures up to 400 GPa using evolutionary\nstructure prediction coupled with ab initio calculations and discovered that\nonly saturated hydrocarbons are thermodynamically stable. Several stable\nmethane-hydrogen co crystals are predicted: 2CH4 * H2, earlier obtained\nexperimentally, is predicted to have I4/m space group and 2-90 GPa stability\nrange at 0 K, and two new thermodynamically stable compounds 2CH4 * 7H2 (P-3m1\nspace group) and CH4 * 9H2 (Cm space group), as potential energy storage\nmaterials. P21/c phase of methane is predicted to be stable at pressures < 8\nGPa; bulk graphane (CH) was shown to be thermodynamically stable at 7-18 and\n18-50 GPa and 0 K in the P-3m and Cmca phases, respectively; polyethylene is\nshown to have a narrow field of stability. We report the p-T-x phase diagram of\nthe C-H system and p-T phase diagram of CH4.",
        "positive": "SDPD Round Robin 2002 Results: Four years after the first structure determination by powder diffractometry\n(SDPD) round robin, a second one shows that SDPD is still not routine."
    },
    {
        "anchor": "Plutonium and Quantum Criticlity: The unusual properties of elemental plutonium have long been a puzzle. It has\nbeen suggested that these properties may be related to quantum criticality [G.\nChapline, J. L. Smith LA Sci 26 (2000) 1]. In this talk we will describe some\nexperimental observations on rare earth and actinide materials which suggest\nthat there are pairing correlations in all f-electron metals, and that the\nanomalous properties of the elemental actinides in the vicinity of\nNp/Pu/Am,even at elevated temperatures, is associated with a critical point in\nthe variation of the density of paired electrons with atomic number.",
        "positive": "Comment on ``Spin and cyclotron energies of electrons in GaAs/GaAlAs\n  quantum wells'': In a recent publication, Pfeffer and Zawadzki [cond-mat/0607150; Phys. Rev. B\n74, 115309 (2006)] attempted a calculation of electron g factor in III-V\nheterostructures. The authors emphasize that their outcome is in strong\ndiscrepancy with our original result [Ivchenko and Kiselev, Sov. Phys.\nSemicond. 26, 827 (1992)] and readily conclude that ``the previous theory of\nthe g factor in heterostructures is inadequate''. We show here that the entire\ndiscrepancy can be tracked down to an additional contribution missing in the\nincomplete elimination procedure of Pfeffer and Zawadzki. This mistake equally\naffects their ``exact'' and approximate results. When the overlooked terms\nstemming from the nondiagonal Zeeman interaction between light hole and\nspin-orbit-split valence states are taken into account in the effective\nelectron dispersion, the results of the both approaches applied to the\nthree-level kp model become identical."
    },
    {
        "anchor": "Vacuum ultraviolet 5d$^1$4f$^9$-4f$^{10}$ emission of Ho$^{3+}$ ions in\n  alkaline-earth fluorides: Time-resolved emission, excitation as well as emission decay curves of\nCaF$_2$, SrF$_2$, BaF$_2$ doped with HoF$_3$ were investigated. Most intensive\nemission bands near 168 nm, having long decay time, belong to spin-forbidden\ntransitions from 5d$^1$4f$^9$ high spin (HS) states to ground $^5$I$_8$ states\nof Ho$^{3+}$ ions. Weak spin allowed 5d$^1$4f$^9$(LS)-4f$^{10}$ emission band\nat 158 nm was observed only in CaF$_2$-Ho crystals. Spin allowed and\nspin-forbidden excitation bands were observed in all crystals near 166 and 155\nnm respectively. Fast component of spin-forbidden emissions due to multiphonon\nrelaxation to low-lying 4f$^{10}$ Ho$^{3+}$ level was observed for all\ncrystals.",
        "positive": "The difference between Si and Ge(001) surfaces in the initial stages of\n  growth: The initial stages of growth of Ge and Si on the Ge(001) surface are studied\nand compared to growth on the Si(001) surface. Metastable rows of diluted\nad-dimers exist on both surfaces as intermediate stages of epitaxial growth.\nUnexpectedly, for Ge(001) these rows are found exclusively in the <310>\ndirections, whereas on Si(001) the preferred direction is <110>. This\nqualitative difference between Si and Ge surfaces reflects the subtle\ndifference in the chemistry of these two elements, which has direct\nconsequences for epitaxial growth on these surfaces."
    },
    {
        "anchor": "Halbach arrays at the nanoscale from chiral spin textures: Mallinson's idea that some spin textures in planar magnetic structures could\nproduce an enhancement of the magnetic flux on one side of the plane at the\nexpense of the other gave rise to permanent magnet configurations known as\nHalbach magnet arrays. Applications range from wiggler magnets in particle\naccelerators and free electron lasers, to motors, to magnetic levitation\ntrains, but exploiting Halbach arrays in micro- or nanoscale spintronics\ndevices requires solving the problem of fabrication and field metrology below\n100 {\\mu}m size. In this work we show that a Halbach configuration of moments\ncan be obtained over areas as small as 1 x 1 {\\mu}m^2 in sputtered thin films\nwith N\\'eel-type domain walls of unique domain wall chirality, and we measure\ntheir stray field at a controlled probe-sample distance of 12.0 x 0.5 nm.\nBecause here chirality is determined by the interfacial Dyzaloshinkii-Moriya\ninteraction the field attenuation and amplification is an intrinsic property of\nthis film, allowing for flexibility of design based on an appropriate\ndefinition of magnetic domains. 100 nm-wide skyrmions illustrate the smallest\nkind of such structures, for which our measurement of stray magnetic fields and\nmapping of the spin structure shows they funnel the field toward one specific\nside of the film given by the sign of the Dyzaloshinkii-Moriya interaction\nparameter D.",
        "positive": "Neutron Diffraction Reveals the Existence of Confined Water in\n  Triangular and Hexagonal Channels of Modified YPO4 at Elevated Temperatures: We provide experimental evidence for confinement of water molecules in the\npores of hexagonal structure of YPO4 at elevated temperatures upto 600 K using\npowder neutron diffraction. In order to avoid the large incoherent scattering\nfrom the hydrogen, deuterated samples of doped YPO4:Ce-Eu were used for\ndiffraction measurements. The presence of water molecules in the triangular and\nhexagonal pores in the hexagonal structure was established by detailed\nsimulation of the diffraction pattern and Rietveld refinement of the\nexperimental data. It was observed that the presence of water leads\nspecifically to suppression of the intensity of a peak around Q = 1.04\n{\\AA}-1while the intensity of peaks around Q=1.83{\\AA}-1 is enhanced in the\nneutron diffraction pattern. We estimate the number of water molecules as 2.36\n(6) per formula units at 300 K and the sizes of the hexagonal and triangular\npores as7.2 (1) {\\AA} and 4.5 (1) {\\AA}, respectively. With increase in\ntemperature, the water content in both the pores decreases above 450 K and\nvanishes around 600 K. Analysis of the powder diffraction data reveals that the\nhexagonal structure with the pores persist up to 1273 K, and transforms to\nanother structure at 1323 K. The high temperature phase is not found to have\nthe zircon or the monazite type structure, but a monoclinic structure (space\ngroup P2/m) with lattice parameters am= 6.826 (4) {\\AA}, bm= 6.645 (4) {\\AA},\ncm= 10.435 (9){\\AA}, and \\b{eta}= 107.21 (6){\\deg}. The monoclinic structure\nhas about 14 % smaller volume than the hexagonal structure which essentially\nreflects the collapse of the pores. The phase transition and the change in the\nvolume are also confirmed by x-ray diffraction measurements. The hexagonal to\nthe monoclinic phase transition is found to be irreversible on cooling to room\ntemperature."
    },
    {
        "anchor": "Guest-induced structural deformation in Cu-based Metal-Organic Framework\n  upon hydrocarbon adsorption: In a world where capture and separation processes represent above 10% of\nglobal energy consumption, novel porous materials, such as Metal-Organic\nFrameworks (MOFs) used in adsorption-based processes are a promising\nalternative to dethrone the high-energy-demanding distillation. Shape and size\ntailor-made pores in combination with Lewis acidic sites can enhance the\nadsorbate-adsorbent interactions. Understanding the underlying mechanisms of\nadsorption is essential to designing and optimizing capture and separation\nprocesses. Herein, we analyze the adsorption behaviour of light hydrocarbons\n(methane, ethane, ethylene, propane, and propylene) in two synthesized\ncopper-based MOFs, Cu-MOF-74 and URJC-1. The experimental and computational\nadsorption curves reveal a limited effect of the exposed metal centers on the\nolefins. The lower interaction Cu-olefin is also reflected in the calculated\nenthalpy of adsorption and binding geometries. Moreover, the diamond-shaped\npores' deformation upon external stimuli is first reported in URJC-1. This\nphenomenon is highlighted as the key to understanding the adsorbent's\nresponsive mechanisms and potential in future industrial applications.",
        "positive": "Calculating optical absorption spectra of thin polycrystalline films:\n  Structural disorder and site-dependent van der Waals interaction: We propose a new approach for calculating the change of the absorption\nspectrum of a molecule when moved from the gas phase to a crystalline\nmorphology. The so-called gas-to-crystal shift $\\Delta{\\cal E}_m$ is mainly\ncaused by dispersion effects and depends sensitively on the molecule's specific\nposition in the nanoscopic setting. Using an extended dipole approximation, we\nare able to divide $\\Delta{\\cal E}_m= -Q W_{m}$ in two factors where $Q$\ndepends only on the molecular species and accounts for all non-resonant\nelectronic transitions contributing to the dispersion, while $W_m$ is a sum\nrunning over the position of all molecules expressing the site-dependence of\nthe shift in a given molecular structure. The ability of our approach to\npredict absorption spectra is demonstrated using the example of polycrystalline\nfilms of 3,4,9,10-perylene-tetracarboxylic-diimide (PTCDI)."
    },
    {
        "anchor": "Amorphous nucleation precursor in highly nonequilibrium fluids: Dynamical density functional simulations reveal structural aspects of crystal\nnucleation in undercooled liquids: the first appearing solid is amorphous,\nwhich promotes the nucleation of bcc crystals, but suppresses the appearance of\nthe fcc and hcp phases. These findings are associated with features of the\neffective interaction potential deduced from the amorphous structure.",
        "positive": "Organic-mineral interactions under natural conditions -- a computational\n  study of flavone adsorption on smectite clay: Interactions between organic species and natural minerals are fundamental to\nthe processes around us. With the aid of molecular dynamics simulations, we\nidentify key adsorption mechanisms of apigenin on smectite clay minerals. The\nmechanism is highly sensitive to the pH -- changing from co-crystallisation in\nacidic-to-neutral solutions to the ion-bridging in mild-alkaline. The ionic\nspecies play a significant role in alkaline environments: the deprotonated\napigenin species chelate metals, which, in turn, leads to the formation of a\nstable organic-metal-mineral complex and stronger adsorption in the presence of\ndivalent cations.Smectite clays buffer the solution to mildly alkaline; hence,\nthe type of exchangeable cations in the clay will be critical in determining\nthe adsorption mechanism and organic retention capacity. Overall, our study\nshowcases a computational strategy that can be transferred to a wide variety of\norganic-mineral systems in the natural environment."
    },
    {
        "anchor": "Effect of Piezoelectric Polarization on Phonon Relaxation Rates in\n  Binary Wurtzite Nitrides: The piezoelectric (PZ) polarization effect enhances the phonon group velocity\nin wurtzite nitrides. This enhancement influences the phonon relaxation rates.\nWe calculate the modified phonon relaxation rates in binary wurtzite nitrides\n(GaN, AlN and InN) by considering process like umklapp process, point defect,\ndislocation, boundary and phonon-electron scattering. The result will be useful\nto study the effect of PZ polarization on thermal conductivity of binary\nwurtzite nitrides (GaN, AlN and InN).",
        "positive": "Heterointerface effects in the electro-intercalation of van der Waals\n  heterostructures: Molecular-scale manipulation of electronic/ionic charge accumulation in\nmaterials is a preeminent challenge, particularly in electrochemical energy\nstorage. Layered van der Waals (vdW) crystals exemplify a diverse family of\nmaterials that permit ions to reversibly associate with a host atomic lattice\nby intercalation into interlamellar gaps. Motivated principally by the search\nfor high-capacity battery anodes, ion intercalation in composite materials is a\nsubject of intense study. Yet the precise role and ability of heterolayers to\nmodify intercalation reactions remains elusive. Previous studies of vdW hybrids\nrepresented ensemble measurements at macroscopic films/powders, which do not\npermit the isolation and investigation of the chemistry at individual\n2-dimensional (2D) interfaces. Here, we demonstrate the intercalation of\nlithium at the level of individual atomic interfaces of dissimilar vdW layers.\nElectrochemical devices based on vdW heterostructures comprised of\ndeterministically stacked hexagonal boron nitride, graphene (G) and molybdenum\ndichalcogenide (MoX2; X = S, Se) layers are fabricated, enabling the direct\nresolution of intermediate stages in the intercalation of discrete\nheterointerfaces and the extent of charge transfer to individual layers.\nOperando magnetoresistance and optical spectroscopy coupled with\nlow-temperature quantum magneto-oscillation measurements show that the creation\nof intimate vdW heterointerfaces between G and MoX2 engenders over 10-fold\naccumulation of charge in MoX2 compared to MoX2/MoX2 homointerfaces, while\nenforcing a more negative intercalation potential than that of bulk MoX2 by at\nleast 0.5 V. Beyond energy storage, our new combined experimental and\ncomputational methodology to manipulate and characterize the electrochemical\nbehavior of layered systems opens up new pathways to control the charge density\nin 2D (opto)electronic devices."
    },
    {
        "anchor": "First principles characterization of the P2_1ab ferroelectric phase of\n  Bi2WO6: The structural, dielectric, dynamical, elastic, piezoelectric and nonlinear\noptical (second-order susceptibility and Pockels tensors) properties of Bi2$WO6\nin its P2_1ab ferroelectric ground state are determined using density\nfunctional theory. The calculation of infrared and Raman spectra on single\ncrystal allowed us to clarify the assignment of experimental phonon modes,\nconsidering the good agreement between the calculated and the experimental\nRaman spectra obtained on polycrystal. The calculation of the elastic constants\nconfirms the elastic stability of the crystal and allow us to estimate the\nYoung and shear moduli of polycrystalline samples. The piezoelectric constants\nhave significant intrinsic values comparable to those of prototypical ABO3\nferroelectrics. The electro-optic response is strongly dominated by the ionic\ncontribution of transverse optic modes, yielding sizable Pockels coefficients\naround 9 pm/V along the polar direction.",
        "positive": "Magnetic Neutron Scattering of Thermally Quenched K-Co-Fe Prussian Blue\n  Analogue Photomagnet: Magnetic order in the thermally quenched photomagnetic Prussian blue analogue\ncoordination polymer K0.27Co[Fe(CN)6]0.73[D2O6]0.27 1.42D2O has been studied\ndown to 4 K with unpolarized and polarized neutron powder diffraction as a\nfunction of applied magnetic field. Analysis of the data allows the onsite\ncoherent magnetization of the Co and Fe spins to be established. Specifically,\nmagnetic fields of 1 T and 4 T induce moments parallel to the applied field,\nand the sample behaves as a ferromagnet with a wandering axis."
    },
    {
        "anchor": "Formation of calcium sulfate through the aggregation of sub-3 nm\n  anhydrous primary species: The formation of crystalline calcium sulfate (CaSO4*xH2O) polymorphs from\naqueous solutions is assumed to occur via a single-step process following the\nclassical nucleation paradigm. However, although recent research contradicts\nthis classical picture and indicates that CaSO4*2H2O forms at room temperature\nthrough multiple steps at different length and time-scales, these steps have so\nfar not been quantified. By using in situ and fast time-resolved small angle\nX-ray scattering (SAXS), we demonstrate that the nucleation and growth of\nCaSO4*2H2O involves at the very initial stages the formation of well-defined,\nprimary species of < 3 nm in length (stage I). Stage II of the reaction is\ncharacterized by the arrangement of these primary species into domains, while\nin stage III these domains condense into larger aggregates. Based on volume\nfractions and electron density considerations we propose that the fast forming\nprimary species from supersaturated aqueous CaSO4 solutions are composed of\nanhydrous Ca-SO4-cores. The first three stages of nucleation and aggregation of\nthe primary species are followed by a final stage (stage IV), where the primary\nspecies grow within the aggregates, and eventually transform into gypsum\n(CaSO4*2H2O). This final stage was also confirmed through simultaneously\ncollected wide-angle scattering (diffraction, WAXS) data, which clearly show\nthe growth of gypsum during stage IV only. Our results demonstrate that CaSO4\nformation is driven by the nucleation and aggregation of well-defined anhydrous\nCa-SO4-cores that transform through hydration into gypsum through a complex\nnucleation and growth pathway.",
        "positive": "Enhanced Valley Zeeman Splitting in Fe-Doped Monolayer MoS2: The Zeeman effect offers unique opportunities for magnetic manipulation of\nthe spin degree of freedom (DOF). Recently, valley Zeeman splitting, referring\nto the lifting of valley degeneracy, has been demonstrated in two-dimensional\ntransition metal dichalcogenides (TMDs) at liquid helium temperature. However,\nto realize the practical applications of valley pseudospins, the valley DOF\nmust be controllable by a magnetic field at room temperature, which remains a\nsignificant challenge. Magnetic doping in TMDs can enhance the Zeeman\nsplitting, however, to achieve this experimentally is not easy. Here, we report\nunambiguous magnetic manipulation of valley Zeeman splitting at 300 K (g =\n-6.4) and 10 K (g = -11) in a CVD-grown Fe-doped MoS2 monolayer; the effective\ng factor can be tuned to -20.7 by increasing the Fe dopant concentration, which\nrepresents an approximately fivefold enhancement as compared to undoped MoS2.\nOur measurements and calculations reveal that the enhanced splitting and geff\nfactors are due to the Heisenberg exchange interaction of the localized\nmagnetic moments (Fe 3d electrons) with MoS2 through the d-orbital\nhybridization."
    },
    {
        "anchor": "Graphyne as the anode material of magnesium-ion batteries: ab initio\n  study: Graphyne, a single atomic layer structure of the carbon six-member rings\nconnected by one acetilenic linkage, is a promising anode of rechargeable\nbatteries. In this paper, a first-principle study has been carried out on\ngraphyne as a new candidate for the anode material of magnesium-ion batteries,\nusing density functional theory calculations. The main focus is on the\nmagnesium adsorption on graphyne surface. The structural properties such as\nadsorption height and energy, the most stable adsorption sites, the Band\nstructure and DOS of the pristine graphyne the diverse Mg-decorated graphyne\nstructures, and energy barrier against Mg diffusion are also calculated. As a\nconsequence of the band structure and DOS of graphyne structures, it is found\nthat the pristine graphyne and the Mg-decorated graphyne structures show a\nsemiconducting nature and metallic behavior, respectively. Moreover, the\nmigration behavior of Mg on graphyne for the main diffusion paths is determined\nby the Nudged Elastic Band (NEB) method.",
        "positive": "Phonon study of rhombohedral BS under high pressure: Raman spectra of rhombohedral boron monosulfide (r-BS) were measured under\npressures up to 34 GPa at room temperature. No pressure-induced structural\nphase transition was observed, while strong pressure shift of Raman bands\ntowards higher wavenumbers has been revealed. IR spectroscopy as a\ncomplementary technique has been used in order to completely describe the\nphonon modes of r-BS. All experimentally observed bands have been compared with\ntheoretically calculated ones and modes assignment has been performed. r-BS\nenriched by 10B isotope was synthesized, and the effect of boron isotopic\nsubstitution on Raman spectra was observed and analyzed."
    },
    {
        "anchor": "Oxygen holes and hybridization in the bismuthates: Motivated by the recently renewed interest in the superconducting bismuth\nperovskites, we investigate the electronic structure of the parent compounds\nABiO$_{3}$ (A= Sr, Ba) using $ab$ $initio$ methods and tight-binding (TB)\nmodeling. We use the density functional theory (DFT) in the local density\napproximation (LDA) to understand the role of various interactions in shaping\nthe ABiO$_{3}$ bandstructure near the Fermi level. It is established that\ninteratomic hybridization involving Bi-$6s$ and O-$2p$ orbitals plays the most\nimportant role. Based on our DFT calculations, we derive a minimal TB model and\ndemonstrate that it can describe the properties of the bandstructure as a\nfunction of lattice distortions, such as the opening of a charge gap with the\nonset of the breathing distortion and the associated condensation of holes onto\n$a_{1g}$-symmetric molecular orbitals formed by the O-$2p_{\\sigma}$ orbitals on\ncollapsed octahedra. We also derive a single band model involving the hopping\nof an extended molecular orbital involving both Bi-$6s$ and a linear\ncombination of six O-$2p$ orbitals which provides a very good description of\nthe dispersion and band gaps of the low energy scale bands straddling the\nchemical potential.",
        "positive": "Elastic properties of solid material with various arrangements of\n  spherical voids: In this work the linear elastic properties of materials containing spherical\nvoids are calculated and compared using finite element simulations. The focus\nis on homogeneous solid materials with spherical, empty voids of equal size.\nThe voids are arranged on crystalline lattices (SC, BCC, FCC and HCP structure)\nor randomly, and may overlap in order to produce connected voids. In that way,\nthe entire range of void fraction between 0.00 and 0.95 is covered, including\nclosed-cell and open-cell structures. For each arrangement of voids and for\ndifferent void fractions the full stiffness tensor is computed. From this, the\nYoung's modulus and Poisson ratios are derived for different orientations.\nSpecial care is taken of assessing and reducing the numerical uncertainty of\nthe method. In that way, a reliable quantitative comparison of different void\nstructures is carried out. Among other things, this work shows that the Young's\nmodulus of FCC in the (1 1 1) plane differs from HCP in the (0 0 0 1) plane,\neven though these structures are very similar. For a given void fraction SC\noffers the highest and the lowest Young's modulus depending on the direction.\nFor BCC at a critical void fraction a switch of the elastic behaviour is found,\nas regards the direction in which the Young's modulus is maximised. For certain\ncrystalline void arrangements and certain directions Poisson ratios between 0\nand 1 were found, including values that exceed the bounds for isotropic\nmaterials. For subsequent investigations the full stiffness tensor for a range\nof void arrangements and void fractions are provided in the supplemental\nmaterial."
    },
    {
        "anchor": "Adsorbate induced enhancement of electrostatic non-contact friction: We study the non-contact friction between an atomic force microscope tip and\na metal substrate in the presence of bias voltage. The friction is due to\nenergy losses in the sample created by the electromagnetic field from the\noscillating charges induced on the tip surface by the bias voltage. We show\nthat the friction can be enhanced by many orders of magnitude if the ads orbate\nlayer can support acoustic vibrations. The theory predicts the magnitude and\nthe distance dependence of friction in a good agreement with recent puzzling\nnon-contact friction experiment \\cite{Stipe}. We demonstrate that even an\nisolated adsorbate can produce high enough friction to be measured\nexperimentally.",
        "positive": "Orbital-flop Induced Magnetoresistance Anisotropy in Rare Earth\n  Monopnictide CeSb: The charge and spin of the electrons in solids have been extensively\nexploited in electronic devices and in the development of spintronics. Another\nattribute of electrons - their orbital nature - is attracting growing interest\nfor understanding exotic phenomena and in creating the next-generation of\nquantum devices such as orbital qubits. Here, we report on orbital-flop induced\nmagnetoresistance anisotropy in CeSb. In the low temperature high\nmagnetic-field driven ferromagnetic state, a series of additional minima appear\nin the angle-dependent magnetoresistance. These minima arise from the\nanisotropic magnetization originating from orbital-flops and from the enhanced\nelectron scattering from magnetic multidomains formed around the first-order\norbital-flop transition. The measured magnetization anisotropy can be accounted\nfor with a phenomenological model involving orbital-flops and a spin-valve-like\nstructure is used to demonstrate the viable utilization of orbital-flop\nphenomenon. Our results showcase a contribution of orbital behavior in the\nemergence of intriguing phenomena."
    },
    {
        "anchor": "First-order Reversal Curve Analysis of Phase Transitions in\n  Electrochemical Adsorption: A New Experimental Technique Suggested by\n  Computer Simulations: The first-order reversal curve (FORC) method for analysis of systems\nundergoing hysteresis is applied to dynamical models of electrochemical\nadsorption. In this setting, the method can not only differentiate between\ndiscontinuous and continuous phase transitions, but can also quite accurately\nrecover equilibrium behavior from dynamic analysis for systems with a\ncontinuous phase transition. Discontinuous and continuous phase transitions in\na two-dimensional lattice-gas model are compared using the FORC method. The\nFORC diagram for a discontinuous phase transition is characterized by a\nnegative (unstable) region separating two positive (stable) regions, while such\na negative region does not exist for continuous phase transitions. Experimental\ndata for FORC analysis could easily be obtained by simple reprogramming of a\npotentiostat designed for cyclic-voltammetry experiments.",
        "positive": "MgGa2O4 spinel barrier for magnetic tunnel junctions: coherent tunneling\n  and low barrier height: Epitaxial Fe/magnesium gallium spinel oxide (MgGa2O4)/Fe(001) magnetic tunnel\njunctions (MTJs) were fabricated by magnetron sputtering. Tunnel\nmagnetoresistance (TMR) ratio up to 121% at room temperature (196% at 4 K) was\nobserved, suggesting a TMR enhancement by the coherent tunneling effect in the\nMgGa2O4 barrier. The MgGa2O4 layer had a spinel structure and it showed good\nlattice matching with the Fe layers owing to slight tetragonal lattice\ndistortion of MgGa2O4. Barrier thickness dependence of the tunneling resistance\nand current-voltage characteristics revealed that the barrier height of the\nMgGa2O4 barrier is much lower than that in an MgAl2O4 barrier. This study\ndemonstrates the potential of Ga-based spinel oxides for MTJ barriers having a\nlarge TMR ratio at a low resistance area product."
    },
    {
        "anchor": "Surface Relaxations, Current Enhancements, and Absolute Distances in\n  High Resolution Scanning Tunneling Microscopy: We have performed the most realistic simulation to date of the operation of a\nscanning tunneling microscope. Probe-sample distances from beyond tunneling to\nactual surface contact are covered. We simultaneously calculate forces, atomic\ndisplacements, and tunneling currents, allowing quantitative comparison with\nexperimental values. A distance regime below which the probe becomes unstable\nis identified. It is shown that the real distance differs substantially from\nprevious estimates because of large atomic displacements on the surface and at\nthe probe-tip.",
        "positive": "Understanding Magnetism in Double Double Perovskites: A Complex Multiple\n  Magnetic Sublattice System: Understanding magnetism in multiple magnetic sublattice system, driven by the\ninterplay of varied nature of magnetic exchanges, is on one hand challenging\nand on other hand intriguing. Motivated by the recent synthesis of AA'BB'O_6\ndouble double perovskites with multiple magnetic ions both at A- and B-sites,\nwe investigate the mechanism of magnetic behavior in these interesting class of\ncompounds. We find that the magnetism in such multiple sublattice compounds is\ngoverned by the interplay and delicate balance between two distinct mechanisms,\na) kinetic energy-driven multiple sublattice double exchange mechanism and b)\nthe conventional super-exchange mechanism. The derived spin Hamiltonian based\non first-principles calculations is solved by the classical Monte Carlo\ntechnique which reproduces the observed magnetic properties. Finally, the\ninfluence of off-stoichiometry, as in experimental samples, is discussed. Some\nof these double double perovskite compounds are found to possess large total\nmagnetic moment and also are found to be half-metallic, which raises the hope\nof future applications of these large magnetic moment half-metallic oxides in\nspintronics and memory devices."
    },
    {
        "anchor": "Fully spin-polarized nodal loop semimetals in alkaline-metal\n  monochalcogenide monolayers: Topological semimetals in ferromagnetic materials have attracted enormous\nattention due to the potential applications in spintronics. Using the\nfirst-principles density functional theory together with an effective lattice\nmodel, here we present a new family of topological semimetals with a fully\nspin-polarized nodal loop in alkaline-metal monochalcogenide $MX$ ($M$ = Li,\nNa, K, Rb, Cs; $X$ = S, Se, Te) monolayers. The half-metallic ferromagnetism\ncan be established in $MX$ monolayers, in which one nodal loop formed by two\ncrossing bands with the same spin components is found at the Fermi energy. This\nnodal loop half-metal survives even when considering the spin-orbit coupling\nowing to the symmetry protection provided by the $\\mathcal{M}_{z}$ mirror\nplane. The quantum anomalous Hall state and Weyl-like semimetal in this system\ncan be also achieved by rotating the spin from the out-of-plane to the in-plane\ndirection. The $MX$ monolayers hosting rich topological phases thus offer an\nexcellent materials platform for realizing the advanced spintronics concepts.",
        "positive": "Sulfur doping effects on the electronic and geometric structures of\n  graphitic carbon nitride photocatalyst: insights from first principles: We present here results of our first principles studies of the sulfur doping\neffects on the electronic and geometric structures of graphitic carbon nitride\n(g-C3N4). Using the Ab initio thermodynamics approach combined with some\nkinetic analysis, we reveal the favorable S-doping configurations By analyzing\nthe valence charge densities of the doped and un-doped systems, we find that\nsulfur partially donates its px- and py- electrons to the system with some back\ndonation to the S pz-states. To obtain accurate description of the excited\nelectronic states, we calculate the electronic structure of the systems using\nthe GW method. The band gap width calculated for g-C3N4 is found to be equal to\n2.7 eV that is in agreement with experiment. We find the S doping to cause a\nsignificant narrowing the gap. Furthermore, the electronic states just above\nthe gap become occupied upon doping that makes the material a conductor.\nAnalysis of the projected local densities of states provides insight into the\nmechanism underlying such dramatic changes in the electronic structure of\ng-C3N4 upon the S doping. Based on our results, we propose a possible\nexplanation for the S doping effect on the photo-catalytic properties of g-C3N4\nobserved in the experiments."
    },
    {
        "anchor": "Hybrid functional calculations of the Al impurity in silica: Hole\n  localization and electron paramagnetic resonance parameters: We performed first-principle calculations based on the supercell and cluster\napproaches to investigate the neutral Al impurity in smoky quartz. Electron\nparamagnetic resonance measurements suggest that the oxygens around the Al\ncenter undergo a polaronic distortion which localizes the hole being on one of\nthe four oxygen atoms. We find that the screened exchange hybrid functional\nsuccessfully describes this localization and improves on standard local density\napproaches or on hybrid functionals that do not include enough exact exchange\nsuch as B3LYP. We find a defect level at about 2.5 eV above the valence band\nmaximum, corresponding to a localized hole in a O 2p orbital. The calculated\nvalues of the g tensor and the hyperfine splittings are in excellent agreement\nwith experiment.",
        "positive": "Machine learning enabled surrogate crystal plasticity model for\n  spatially resolved 3D orientation evolution under uniaxial tension: We present a novel machine learning based surrogate modeling method for\npredicting spatially resolved 3D microstructure evolution of polycrystalline\nmaterials under uniaxial tensile loading. Our approach is orders of magnitude\nfaster than the existing crystal plasticity methods enabling the simulation of\nlarge volumes that would be otherwise computationally prohibitive. This work is\na major step beyond existing ML-based modeling results, which have been limited\nto either 2D structures or only providing average, rather than local,\npredictions. We demonstrate the speed and accuracy of our surrogate model\napproach on experimentally measured microstructure from high-energy X-ray\ndiffraction microscopy of a face-centered cubic copper sample, undergoing\ntensile deformation."
    },
    {
        "anchor": "Metastable precursors during the oxidation of the Ru(0001) surface: Using density-functional theory, we predict that the oxidation of the\nRu(0001) surface proceeds via the accumulation of sub-surface oxygen in\ntwo-dimensional islands between the first and second substrate layer. This\nleads locally to a decoupling of an O-Ru-O trilayer from the underlying metal.\nContinued oxidation results in the formation and stacking of more of these\ntrilayers, which unfold into the RuO_2(110) rutile structure once a critical\nfilm thickness is exceeded. Along this oxidation pathway, we identify various\nmetastable configurations. These are found to be rather close in energy,\nindicating a likely lively dynamics between them at elevated temperatures,\nwhich will affect the surface chemical and mechanical properties of the\nmaterial.",
        "positive": "Structurally driven metamagnetism in MnP and related Pnma compounds: We investigate the structural conditions for metamagnetism in MnP and related\nmaterials using Density Functional Theory. A magnetic stability plot is\nconstructed taking into account the two shortest Mn-Mn distances. We find that\na particular Mn-Mn separation plays the dominant role in determining the change\nfrom antiferromagnetic to ferromagnetic order in such systems. We establish a\ngood correlation between our calculations and structural and magnetic data from\nthe literature. Based on our approach it should be possible to find new\nMn-containing alloys that possess field-induced metamagnetism and associated\nmagnetocaloric effects."
    },
    {
        "anchor": "Soft X-ray Resonant Magnetic Scattering Studies on Fe/CoO Exchange Bias\n  System: We have used soft X-ray Resonant Magnetic Scattering (XRMS) to search for the\npresence of an effective ferromagnetic moment belonging to the\nantiferromagnetic (AF) layer which is in close contact with a ferromagnetic (F)\nlayer. Taking advantage of the element specificity of the XRMS technique, we\nhave measured hysteresis loops of both Fe and CoO layers of a CoO(40\n\\AA)/Fe(150 \\AA) exchange bias bilayer. From these measurements we have\nconcluded that the proximity of the F layer induces a magnetic moment in the AF\nlayer. The F moment of the AF layer has two components: one is frozen and does\nnot follow the applied magnetic field and the other one follows in phase the\nferromagnetic magnetization of the F layer. The temperature dependence of the F\ncomponents belonging to the AF layer is shown and discussed.",
        "positive": "Low-temperature nuclear and magnetic structures of La2O2Se2.Fe2O from\n  X-ray and neutron diffraction measurements: This paper describes the low temperature nuclear and magnetic structures of\nLa2O2Se2.Fe2O by analysis of X-ray and neutron diffraction data. The material\nhas been demonstrated to order antiferromagnetically at low temperatures, with\nTN \\approx 90 K a propagation vector of k = (1/2 0 1/2), resulting in a spin\narrangement similar to that in FeTe, despite there being no apparent lowering\nin symmetry of the nuclear structure."
    },
    {
        "anchor": "Hydrogen diffusion in the proton conductor Gd-doped barium cerate: The energy landscape and diffusion barriers of protonic defects in Gd-doped\nBaCeO3, a compound candidate as electrolyte for protonic ceramic fuel cells,\nhave been investigated by density functional theory calculations, starting from\na previously computed energy landscape consisting of 16 kinds of stable sites\n(8 close to dopants and 8 far from them). The simplified string method has been\nused to determine accurately the Minimum Energy Paths between those sites, that\nmight imply either proton reorientations, intra-octahedral or inter-octahedral\nhopping mechanisms. At contrast with simple cubic perovskites such as barium\nstannate or barium zirconate, very different values for energy barriers (from\n0.02 eV to 0.58 eV) are found in this highly distorted orthorhombic perovskite,\nand no specific process appears to be clearly rate-limiting. Some\ninter-octahedral hoppings (when possible) are found to be more favourable than\nthe intra-octahedral ones, while reorientations exhibit a wide range of energy\nbarriers.",
        "positive": "Theoretical Efficiency Comparison between Carrier Multiplication and\n  Down-Conversion 3rd Generation Solar Cell Designs: Methods of exceeding the detailed balance limit for a single junction solar\ncell have included down-converting high energy photons to produce two photons;\nand carrier multiplication, whereby high energy photons produce more than one\nelectron-hole pair. Both of the methods obey the conservation of energy in\nsimilar ways, and effectively produce a higher current in the solar cell. Due\nto this similarity, it has been assumed that there is no thermodynamic\ndifference between the two methods. Here, we compare the two methods using a\ngeneralized approach based on Kirchhoff's law of radiation and develop a new\nmodel for carrier multiplication. We demonstrate that there is an entropic\npenalty to be paid for attempting to accomplish all-in-one splitting in carrier\nmultiplication systems, giving a small thermodynamic - and therefore efficiency\n- advantage to spectral splitting prior to reaching the solar cell. We show\nthis analytically using a derivation of basic thermodynamic identities;\nnumerically by solving for the maximal efficiency; and generally using\nheat-generation arguments. Our result modifies the existing literature on\nentropy generation limits in solar cells, and creates a new distinction among\n3rd generation photovoltaic technologies."
    },
    {
        "anchor": "Phase field modeling of electrochemistry II: Kinetics: The kinetic behavior of a phase field model of electrochemistry is explored\nfor advancing (electrodeposition) and receding (electrodissolution) conditions\nin one dimension. We described the equilibrium behavior of this model in [J. E.\nGuyer, W. J. Boettinger, J.A. Warren, and G. B. McFadden, ``Phase field\nmodeling of electrochemistry I: Equilibrium'', cond-mat/0308173]. We examine\nthe relationship between the parameters of the phase field method and the more\ntypical parameters of electrochemistry. We demonstrate ohmic conduction in the\nelectrode and ionic conduction in the electrolyte. We find that, despite making\nsimple, linear dynamic postulates, we obtain the nonlinear relationship between\ncurrent and overpotential predicted by the classical ``Butler-Volmer'' equation\nand observed in electrochemical experiments. The charge distribution in the\ninterfacial double layer changes with the passage of current and, at\nsufficiently high currents, we find that the diffusion limited deposition of a\nmore noble cation leads to alloy deposition with less noble species.",
        "positive": "Ring-originated anisotropy of local structural ordering in amorphous and\n  crystalline silicon dioxide: Rings comprising chemically bonded atoms are essential topological motifs for\nthe structural ordering of network-forming materials. Quantification of such\nlarger motifs beyond short-range pair correlation is essential for\nunderstanding the linkages between the orderings and macroscopic behaviors.\nHere, we propose two quantitative analysis methods based on rings. The first\nmethod quantifies rings by two geometric indicators: roundness and roughness.\nThese indicators reveal the linkages between highly symmetric rings and crystal\nsymmetry in silica and that the structure of amorphous silica mainly consists\nof distorted rings. The second method quantifies a spatial correlation function\nthat describes three-dimensional atomic densities around rings. A comparative\nanalysis among the functions for different degrees of ring symmetries reveals\nthat symmetric rings contribute to the local structural order in amorphous\nsilica. Another analysis of amorphous models with different orderings reveals\nanisotropy of the local structural ordering around rings; this contributes to\nbuilding the intermediate-range ordering."
    },
    {
        "anchor": "Stress and strain in symmetric and asymmetric elasticity: Usual introductions of the concept of motion are not well adapted to a\nsubsequent, strictly tensorial, theory of elasticity. The consideration of\narbitrary coordinate systems for the representation of both, the points in the\nlaboratory, and the material points (comoving coordinates), allows to develop a\nsimple, old fashioned theory, where only measurable quantities -like the Cauchy\nstress- need be introduced. The theory accounts for the possibility of\nasymmetric stress (Cosserat elastic media), but, contrary to usual developments\nof the theory, the basic variable is not a micro-rotation, but the more\nfundamental micro-rotation velocity. The deformation tensor here introduced is\nthe proper tensorial equivalent of the poorly defined deformation \"tensors\" of\nthe usual theory. It is related to the deformation velocity tensor via the\nmatricant. The strain is the logarithm of the deformation tensor. As the theory\naccounts for general Cosserat media, the strain is not necessarily symmetric.\nHooke's law can be properly introduced in the material coordinates (as the\nstiffness is a function of the material point). A particularity of the theory\nis that the components of the stiffness tensor in the material (comoving)\ncoordinates are not time-dependent. The configuration space is identified to\nthe part of the Lie group GL(3)+, that is geodesically connected to the origin\nof the group.",
        "positive": "Photoinduced suppression of the ferroelectric instability in PbTe: The interactions between electrons and phonons drive a large array of\ntechnologically relevant material properties including ferroelectricity,\nthermoelectricity, and phase-change behaviour. In the case of many group IV-VI,\nV, and related materials, these interactions are strong and the materials exist\nnear electronic and structural phase transitions. Their close proximity to\nphase instability produces a fragile balance among the various properties. The\nprototypical example is PbTe whose incipient ferroelectric behaviour has been\nassociated with large phonon anharmonicity and thermoelectricity. Experimental\nmeasurements on PbTe reveal anomalous lattice dynamics, especially in the soft\ntransverse optical phonon branch. This has been interpreted in terms of both\ngiant anharmonicity and local symmetry breaking due to off-centering of the Pb\nions. The observed anomalies have prompted renewed theoretical and\ncomputational interest, which has in turn revived focus on the extent that\nelectron-phonon interactions drive lattice instabilities in PbTe and related\nmaterials. Here, we use Fourier-transform inelastic x-ray scattering (FT-IXS)\nto show that photo-injection of free carriers stabilizes the paraelectric\nstate. With support from constrained density functional theory (CDFT)\ncalculations, we find that photoexcitation weakens the long-range forces along\nthe cubic direction tied to resonant bonding and incipient ferroelectricity.\nThis demonstrates the importance of electronic states near the band edges in\ndetermining the equilibrium structure."
    },
    {
        "anchor": "Hysteresis from dynamically pinned sliding states: We report a surprising hysteretic behavior in the dynamics of a simple\none-dimensional nonlinear model inspired by the tribological problem of two\nsliding surfaces with a thin solid lubricant layer in between. In particular,\nwe consider the frictional dynamics of a harmonic chain confined between two\nrigid incommensurate substrates which slide with a fixed relative velocity.\nThis system was previously found, by explicit solution of the equations of\nmotion, to possess plateaus in parameter space exhibiting a remarkable\nquantization of the chain center-of-mass velocity (dynamic pinning) solely\ndetermined by the interface incommensurability. Starting now from this\nquantized sliding state, in the underdamped regime of motion and in analogy to\nwhat ordinarily happens for static friction, the dynamics exhibits a large\nhysteresis under the action of an additional external driving force F_ext. A\ncritical threshold value F_c of the adiabatically applied force F_ext is\nrequired in order to alter the robust dynamics of the plateau attractor. When\nthe applied force is decreased and removed, the system can jump to intermediate\nsliding regimes (a sort of ``dynamic'' stick-slip motion) and eventually\nreturns to the quantized sliding state at a much lower value of F_ext. On the\ncontrary no hysteretic behavior is observed as a function of the external\ndriving velocity.",
        "positive": "Instrument for in-situ orientation of superconducting thin-film\n  resonators used for electron-spin resonance experiments: When used in Electron-Spin Resonance (ESR) measurements, superconducting\nthin-film resonators must be precisely oriented relative to the external\nmagnetic field in order to prevent the trapping of magnetic flux and the\nassociated degradation of resonator performance. We present a compact design\nsolution for this problem that allows in-situ control of the orientation of the\nresonator at cryogenic temperatures. Tests of the apparatus show that when\nproper alignment is achieved, there is almost no hysteresis in the field\ndependence of the resonant frequency."
    },
    {
        "anchor": "Ferromagnetism and spin polarized charge carriers in In$_{2}$O$_{3}$\n  thin films: We present evidence for spin polarized charge carriers in In$_2$O$_3$ films.\nBoth In$_2$O$_3$ and Cr doped In$_2$O$_3$ films exhibit room temperature\nferromagnetism after vacuum annealing, with a saturation moment of\napproximately 0.5 emu/cm$^3$. We used Point Contact Andreev Reflection\nmeasurements to directly determine the spin polarization, which was found to be\napproximately 50$\\pm$5% for both compositions. These results are consistent\nwith suggestions that the ferromagnetism observed in certain oxide\nsemiconductors may be carrier mediated.",
        "positive": "Enhancing plasticity in high-entropy refractory ceramics via tailoring\n  valence electron concentration: Bottom-up design of high-entropy ceramics is a promising approach for\nrealizing materials with unique combination of high hardness and\nfracture-resistance at elevated temperature. This work offers a simple yet\nfundamental design criterion - valence electron concentration (VEC) > ~9.5\ne-/f.u. to populate bonding metallic states at the Fermi level - for selecting\nelemental compositions that may form rocksalt-structure (B1) high-entropy\nceramics with enhanced plasticity (reduced brittleness). Single-phase B1\n(HfTaTiWZr)C and (MoNbTaVW)C, chosen as representative systems due to their\nspecific VEC values, are here synthesized and tested. Nanoindentation arrays at\nvarious loads and depths statistically show that (HfTaTiWZr)C (VEC=8.6 e-/f.u.)\nis hard but brittle, whilst (MoNbTaVW)C (VEC=9.4 e-/f.u.) is hard and\nconsiderably more resistant to fracture than (HfTaTiWZr)C. Ab initio molecular\ndynamics simulations and electronic-structure analysis reveal that the improved\nfracture-resistance of (MoNbTaVW)C subject to tensile and shear deformation may\noriginate from the intrinsic material's ability to undergo local lattice\ntransformations beyond tensile yield points, as well as from relatively facile\nactivation of lattice slip. Additional simulations, carried out to follow the\nevolution in mechanical properties as a function of temperature, suggest that\n(MoNbTaVW)C may retain good resistance to fracture up to ~900-1200K, whereas\n(HfTaTiWZr)C is predicted to remain brittle at all investigated temperatures."
    },
    {
        "anchor": "Coulomb Blockade in a Silicon/Silicon-Germanium Two-Dimensional Electron\n  Gas Quantum Dot: We report the fabrication and electrical characterization of a single\nelectron transistor in a modulation doped silicon/silicon-germanium\nheterostructure. The quantum dot is fabricated by electron beam lithography and\nsubsequent reactive ion etching. The dot potential and electron density are\nmodified by laterally defined side gates in the plane of the dot. Low\ntemperature measurements show Coulomb blockade with a single electron charging\nenergy of 3.2 meV.",
        "positive": "Tailoring interface mixing and magnetic properties in (111) Permalloy/Pt\n  multilayers: We present deposition and characterization of multilayers consisting of 20\nrepetitions of 15 $\\r{A}$ thick permalloy Ni$_{80}$Fe$_{20}$ at. \\% (Py) and 5\n$\\r{A}$ Pt. The samples were prepared by two different sputter deposition\nmethods, namely dc magnetron sputtering (dcMS) and high power impulse magnetron\nsputtering (HiPIMS), that represent low and moderate ionized flux fraction of\nthe film forming material, respectively, for deposition of the Py layers. The\neffect of substrate roughness, working gas pressure and sputter power on the\nin-plane uniaxial magnetic anisotropy of the films are studied. The multilayers\nwere characterized by X-ray reflectivity and diffraction, and by\nmagneto-optical Kerr effect (MOKE). It is shown that HiPIMS deposition produces\nmultilayers with unique surface roughness regardless of the substrate surface\nroughness. Multilayers prepared by both dcMS and HiPIMS deposition present a\nstrong (111) texture normal to the film plane. The results show that utilizing\nHiPIMS for deposition of the Py layer leads to a minimum interface mixing\nbetween individual layers compared to dcMS deposition performed at sputter\npower. This is associated with the smooth surface of Py deposited by HiPIMS.\nHowever, this sharp interface results in higher coercivity and an opening in\nthe hard axis hysteresis loops while multilayers with intermixing present well\ndefined in-plane uniaxial anisotropy i.e. a linear hard axis. Comparison with\nPy/Cu and Py/CuPt multilayers, prepared under identical conditions using\nHiPIMS, suggests that poor in-plane uniaxial anisotropy is obtained in the\nPy/Pt case, caused by the inverse magnetostriction arising from the large\nlattice mismatch between Py and Pt. The Py/Pt multilayers that exhibit\ninterface mixing have a more relaxed interface and thus presents negligible\ninverse magnetostriction and have better defined anisotropy."
    },
    {
        "anchor": "Electrical control of spin coherence in ZnO: Electric field enhanced electron spin coherence is characterized using\ntime-resolved Faraday rotation spectroscopy in n-type ZnO epilayers grown by\nmolecular beam epitaxy. An in-plane dc electric field E almost doubles the\ntransverse spin lifetime at 20 K, without affecting the effective g-factor.\nThis effect persists till high temperatures, but decreases with increasing\ncarrier concentration. Comparisons of the variations in the spin lifetime, the\ncarrier recombination lifetime and photoluminescence lifetimes indicate that\nthe applied E enhances the radiative recombination rate. All observed effects\nare independent of crystal directionality and are performed at low magnetic\nfields (B < 0.2 T).",
        "positive": "Modeling and characterizing single-walled carbon nanotubes by pressure\n  probe: We compare the behavior of bond lengths, cross sectional shape and bulk\nmodulus in equilibrium structure at ambient conditions and under hydrostatic\npressure of all the three kinds of uncapped single walled carbon nanotubes.\nResults of our numerical calculations show that two bond lengths completely\ndescribe the structure of achiral SWNT whereas only one bond length is required\nto determine structure of chiral SWNT. In armchair tubes, one bond length is\nfound to be larger than that of graphitic value while in zigzag tubes one bond\nlength has a constant value. These bond lengths are very sensitive to tube\nradius. In chiral tubes, the value of bond length is found to depend on the\nchirality and slightly on the tube radius. Different responses of these bond\nlengths are found on application of pressure. At some critical pressure, both\nbond lengths become equal to each other in achiral tubes. An analysis regarding\nthe cross sectional shape of the nanotubes and its pressure dependence has also\nbeen done. The shape transition, from circular to oval shape takes place. At\nthis transition, the behavior of bond lengths is found different and dependent\non the chirality of the tubes. Chiral tubes with chiral angle which is mid way\nbetween zigzag and armchair tubes are found to have most prominent effects of\nchirality. Thus we demonstrate that pressure is a useful probe to characterize\nvarious kinds of carbon nanotubes."
    },
    {
        "anchor": "Magnetic relaxation and correlating effective magnetic moment with\n  particle size distribution in maghemite nanoparticles: The role of particle size distribution inherently present in magnetic\nnanoparticles (NPs) is examined in considerable detail in relation to the\nmeasured magnetic properties of oleic acid-coated maghemite\n({\\gamma}-Fe$_2$O$_3$) NPs. Transmission electron microscopy (TEM) of the\nsol-gel synthesized $\\gamma$-$Fe$$_2$$O$$_3$ NPs showed a log-normal\ndistribution of sizes with average diameter $<D>$= 7.04 nm and standard\ndeviation $\\sigma$= 0.78 nm. Magnetization, $M$, vs. temperature (2 K to 350 K)\nof the NPs was measured in an applied magnetic field $H$ up to 90 kOe along\nwith the temperature dependence of the ac susceptibilities, $\\chi$$'$ and\n$\\chi$$\"$, at various frequencies, $f$$_m$, from 10 Hz to 10 kHz. From the\nshift of the blocking temperature from $T$$_B$ =35 K at 10 Hz to $T$$_B$ = 48 K\nat 10 kHz, the absence of any significant interparticle interaction is inferred\nand the relaxation frequency $f$$_o$= 2.6 x 10$^{10}$ Hz and anisotropy\nconstant $K$$_a$= 5.48 x 10$^5$ ergs/cm$^3$ are determined. For $T$ < $T$$_B$,\nthe coercivity $H$$_C$ is practically negligible. For $T$ > $T$$_B$, the data\nof $M$ vs. $H$ up to 90 kOe at several temperatures are analyzed two different\nways: (i) in terms of the modified Langevin function yielding an average\nmagnetic moment per particle $\\mu$$_p$=7300 (500) $\\mu$$_B$; and (ii) in terms\nof log-normal distribution of moments yielding $<$$\\mu$$>$= 6670 $\\mu$$_B$ at\n150 K decreasing to $<$$\\mu$$>$= 6100 $\\mu$$_B$ at 300 K with standard\ndeviations $\\sigma$ $\\approx$ $<$$\\mu$$>$$/2$. The above two approaches yield\nconsistent and physically meaningful results as long as the width parameter,\n$s$, of the log-normal distribution is less than 0.83.",
        "positive": "Generic role of the anisotropic surface free energy on the morphological\n  evolution in a strained-heteroepitaxial solid droplet on a rigid substrate: A systematic study based on the self-consistent dynamical simulations is\npresented for the spontaneous evolution of an isolated thin solid droplet on a\nrigid substrate, which is driven by the surface drift diffusion induced by the\nanisotropic capillary forces (surface stiffness) and mismatch stresses. In this\nwork, we studied the affect of surface free energy anisotropies on the\ndevelopment kinetics of the 'Stranski-Krastanow' island type morphology. The\nanisotropic surface free energy and the surface stiffness were treated with\nwell accepted trigonometric functions. Although, various tilt angles and\nanisotropy constants were considered during simulations, the main emphasis was\ngiven on the effect of rotational symmetries associated with the surface\nHelmholtz free energy topography in 2D space. Our computer simulations revealed\nthe formation of an extremely thin wetting layer during the development of the\nbell-shaped Stranski-Krastanow island through the mass accumulation at the\ncentral region of the droplet via surface drift-diffusion. In the strong\n(anomalous) anisotropy constant domain, we demonstrated the existence of two\ndistinct morphological modes: i) the complete stability of the initial\nCosine-shaped droplet just above a certain anisotropy constant threshold level\nby spontaneous slight readjustments of the base and the height of the cluster;\nii) the Frank-van der Merwe mode of thin film formation for very large values\nof the anisotropy constant by the spreading and coalescence of the droplets\nover the substrate surface. During the course of the simulations, we have\ncontinuously tracked both the morphology (i.e., the peak height, the extension\nof the wetting layer beyond the domain boundaries, and the triple junction\ncontact angle) and energetic (the global Helmholtz free energy changes\nassociated with the total strain and surface energy variations) of the system."
    },
    {
        "anchor": "Hard x-ray standing-wave photoemission study of the interfaces in a\n  BiFeO$_3$/La$_{0.7}$Sr$_{0.3}$MnO$_3$ superlattice: Hybrid multiferroics such as BiFeO$_3$ (BFO) and La$_{0.7}$Sr$_{0.3}$MnO$_3$\n(LSMO) heterostructures are highly interesting functional systems due to their\ncomplex electronic and magnetic properties. One of the key parameters\ninfluencing the emergent properties is the quality of interfaces, where varying\ninterdiffusion lengths can give rise to different chemistry and distinctive\nelectronic states. Here we report high-resolution depth resolved chemical and\nelectronic investigation of BFO/LSMO superlattice using standing-wave hard\nX-ray photoemission spectroscopy in the first-order Bragg as well as\nnear-total-reflection geometry. Our results show that the interfaces of BFO on\ntop of LSMO are atomically abrupt, while the LSMO on top of BFO interfaces show\nan interdiffusion length of around 1.2 unit cells. The two interfaces also\nexhibit different chemical gradients, with the BFO/LSMO interface being\nSr-terminated by a spectroscopically distinctive high binding energy component\nin Sr 2p core-level spectra, which is spatially contained within 1 unit cell\nfrom the interface. From the electronic point of view, unique valence band\nfeatures were observed for bulk-BFO, bulk-LSMO and their interfaces. Our X-ray\noptical analysis revealed a unique electronic signature at the BFO/LSMO\ninterface, which we attribute to the coupling between those respective layers.\nValence band decomposition based on the Bragg-reflection standing-wave\nmeasurement also revealed the band alignment between BFO and LSMO layers. Our\nwork demonstrates that standing-wave hard x-ray photoemission is a reliable\nnon-destructive technique for probing depth-resolved electronic structure of\nburied layers and interfaces with sub-unit-cell resolution. Equivalent\ninvestigations can be successfully applied to a broad class of material such as\nperovskite complex oxides with emergent interfacial phenomena.",
        "positive": "Photoluminescence of focused ion beam implanted\n  Er$^{3+}$:Y$_{2}$SiO$_{5}$ crystals: Erbium doped low symmetry Y$_2$SiO$_5$ crystals attract a lot of attention in\nperspective of quantum information applications. However, only doping of the\nsamples during growth is available up to now, which yields a quite homogeneous\ndoping density. In the present work, we deposit Er$^{3+}$-ions by the focused\nion beam technique at Yttrium sites with several fluences in one sample. With a\nphotoluminescence study of these locally doped Er$^{3+}$:Y$_2$SiO$_5$ crystals,\nwe are able to evaluate the efficiency of the implantation process and develop\nit for the highest efficiency possible. We observe the dependence of the ion\nactivation after the post-implantation annealing on the fluence value."
    },
    {
        "anchor": "Cluster expansion methods from physical concepts: The cluster expansion formalism used in materials science is reconstructed on\nan axiomatic basis with the aims of clarifying underlying concepts and\nimproving computational procedures, and without using conventional cluster\nfunctions. Instead, cluster components of configuration functions are defined\nin an intrinsic manner, which can be viewed as Moebius inversion of conditional\nexpectation. The associated method for fitting a model to a configurational\nsample is grounded entirely in Hilbert space geometry. By constructing models\ndirectly from the given data, we avoid an underdetermination problem to which\nthe conventional approach is subject. Tensor observables are treated on an\nequal footing with scalar observables.",
        "positive": "Methodology for determining the electronic thermal conductivity of\n  metals via direct non-equilibrium ab initio molecular dynamics: Many physical properties of metals can be understood in terms of the free\nelectron model, as proven by the Wiedemann-Franz law. According to this model,\nelectronic thermal conductivity ($\\kappa_{el}$) can be inferred from the\nBoltzmann transport equation (BTE). However, the BTE does not perform well for\nsome complex metals, such as Cu. Moreover, the BTE cannot clearly describe the\norigin of the thermal energy carried by electrons or how this energy is\ntransported in metals. The charge distribution of conduction electrons in\nmetals is known to reflect the electrostatic potential (EP) of the ion cores.\nBased on this premise, we develop a new methodology for evaluating\n$\\kappa_{el}$ by combining the free electron model and non-equilibrium ab\ninitio molecular dynamics (NEAIMD) simulations. We demonstrate that the kinetic\nenergy of thermally excited electrons originates from the energy of the spatial\nelectrostatic potential oscillation (EPO), which is induced by the thermal\nmotion of ion cores. This method directly predicts the $\\kappa_{el}$ of pure\nmetals with a high degree of accuracy."
    },
    {
        "anchor": "Remanence and switching sensitivity in nanodot magnetic arrays: New results are reported of the computer simulations on the magnetic\nbehaviour of magnetic arrays of nanoscopic dots, placed in cells of the square\nlattice. We show that the remanence magnetization $M_r$ decreases with the\narray size. For arrays 50x50, we investigate also the stability of the magnetic\nstructure of an array in an oscillating magnetic field. The damage spreading\ntechnique reveals that this stability increases with the standard deviation\n$\\sigma$ of the switching field of individual elements of the array. On the\nother hand, $M_r$ decreases with $\\sigma$. An optimalization of the system\n(large $M_r$ and large stability) can then be reached at some intermediate\nvalue of $\\sigma$.",
        "positive": "Epitaxial ferroelectric hafnia stabilized by symmetry constraints: Ferroelectric memories experienced a revival in the last decade due to the\ndiscovery of ferroelectricity in HfO$_2$-based nanometer-thick thin films.\nThese films exhibit exceptional silicon compatibility, overcoming the scaling\nand integration obstacles that impeded perovskite ferroelectrics' use in\nhigh-density integrated circuits. The exact phase responsible for\nferroelectricity in hafnia films remains debated with no single factor\nidentified that could stabilize the ferroelectric phase thermodynamically.\nHere, supported by density functional theory (DFT) high-throughput (HT)\ncalculations that screen a broad range of epitaxial conditions, we demonstrate\nconclusively that specific epitaxial conditions achievable with common\nsubstrates such as yttria-stabilized zirconia (YSZ) and SrTiO$_3$ can favor the\npolar Pca2$_1$ phase thermodynamically over other polar phases such as R3m and\nPmn2$_1$ and nonpolar P2$_1$/c phase. The substrate's symmetry\nconstraint-induced shear strain is crucial for the preference of Pca2$_1$. The\nstrain-stability phase diagrams resolve experiment-theory discrepancies and can\nguide the improvement of ferroelectric properties of epitaxial hafnia thin\nfilms."
    },
    {
        "anchor": "Laser Induced Forward Transfer of conducting polymers: We report on laser printing of conducting polymers directly from the solid\nphase. Laser Induced Forward Transfer is employed to deposit P3HT:PCBM films on\nglass/ITO/PEDOT:PSS substrates. P3HT:PCBM is widely used as the active material\nin organic solar cells. Polyaniline films, which are also printed by Laser\nInduced Forward Transfer, find many applications in the field of biotechnology.\nLaser printing parameters are optimized and results are presented. To apply\nsolid-phase laser printing, P3HT:PCBM films are spun cast on quartz substrates,\nwhile aniline is in-situ polymerized on quartz substrates.",
        "positive": "Fast drying of high-alumina MgO-bonded refractory castables: Refractory producers face many challenges in terms of producing\nMgO-containing castables due to the high likelihood of magnesia to hydrate in\ncontact with water, resulting in Mg(OH)2 generation. The expansive feature of\nthis transformation affects the performance of such refractories, as (i) if\nthis hydrated phase is not accommodated in the formed microstructure, ceramic\nlinings with cracks and low green mechanical strength will be obtained; and\n(ii) if crack-free pieces are prepared, they should present low porosity and\nreduced permeability, which require special attention when heating these\nmaterials. This work investigated the ability of various additives in the\noptimization of the drying behavior of Al2O3-MgO castables. Vibratable\ncompositions were tested after incorporating polymeric fibers (PF), an organic\nsalt (OAS), SiO2-based additive (SM) or permeability enhancing active compound\n(MP) into the dry-mixtures. Various experimental measurements were performed to\ninfer the role of the drying agents to prevent the samples explosion and\nwhether they would also influence other properties of the castables. As\nobserved, OAS and MP helped to inhibit the MgO-bonded samples explosion even\nunder severe heating conditions (2-20C/min) and increased their green\nmechanical strength and slag infiltration resistance when compared to the\nadditive-free composition. On the other hand, the addition of polymeric fibers\n(PF) or silica-based compound (SM) to the formulations was not able to prevent\nthe castables explosion when using a high heating rate and other side effects\ncould also be observed when testing these materials. Thus, the selection of\nsuitable drying agents is a key issue, as they may allow the development of\nMgO-bonded castables with enhanced properties and lower spalling risk during\ntheir first thermal treatment."
    },
    {
        "anchor": "Antimony arsenide: Chemical ordering in the compound SbAs: The semimetallic Group V elements display a wealth of correlated electron\nphenomena due to a small indirect band overlap that leads to relatively small,\nbut equal, numbers of holes and electrons at the Fermi energy with high\nmobility. Their electronic bonding characteristics produce a unique crystal\nstructure, the rhombohedral A7 structure, which accommodates lone pairs on each\nsite. Here we show that the A7 structure can display chemical ordering of Sb\nand As, which were previously thought to mix randomly. Our structural\ncharacterization of the compound SbAs is performed by single-crystal and\nhigh-resolution synchrotron x-ray diffraction, and neutron and x-ray pair\ndistribution function analysis. All least-squares refinements indicate ordering\nof Sb and As, resulting in a GeTe-type structure without inversion symmetry.\nHigh-temperature diffraction studies reveal an ordering transition around 550\nK. Transport and infrared reflectivity measurements, along with\nfirst-principles calculations, confirm that SbAs is a semimetal, albeit with a\ndirect band separation larger than that of Sb or As. Because even subtle\nsubstitutions in the semimetals, notably Bi_{1-x}Sb_x, can open semiconducting\nenergy gaps, a further investigation of the interplay between chemical ordering\nand electronic structure on the A7 lattice is warranted.",
        "positive": "Surface spin-transfer torque and spin-injection effective field in\n  ferromagnetic junctions: Unified theory: We consider theoretically a current flowing perpendicular to interfaces of a\nspin-valve type ferromagnetic metallic junction. For the first time an\neffective approach is investigated to calculate a simultaneous action of the\ntwo current effects, namely, the nonequilibrium longitudinal spin injection and\nthe transversal spin-transfer surface torque. Dispersion relation for\nfluctuations is derived and solved. Nonlinear problem is solved about steady\nstate arising due to instability for a thick enough free layer."
    },
    {
        "anchor": "Novel electrically resonant terahertz metamaterials: We present a new class of artificial materials which exhibit a tailored\nresponse to the electrical component of electromagnetic radiation. These\nelectric metamaterials (EM-MMs) are investigated theoretically,\ncomputationally, and experimentally using terahertz time-domain spectroscopy.\nThese structures display a resonant response including regions of negative\npermittivity (epsilon < 0) ranging from ~500 GHz to 1 THz. Conventional\nelectric media such as distributed wires are difficult to incorporate into\nmetamaterials. In contrast, these new localized structures will simplify the\nconstruction of future metamaterials - including those with negative index of\nrefraction - and will enhance the design and fabrication of functional THz\ndevices.",
        "positive": "Kinetic Monte Carlo simulations of oscillatory shape evolution for\n  electromigration-driven islands: The shape evolution of two-dimensional islands under electromigration-driven\nperiphery diffusion is studied by kinetic Monte Carlo (KMC) simulations and\ncontinuum theory. The energetics of the KMC model is adapted to the Cu(100)\nsurface, and the continuum model is matched to the KMC model by a suitably\nparametrized choice of the orientation-dependent step stiffness and step atom\nmobility. At 700 K shape oscillations predicted by continuum theory are\nquantitatively verified by the KMC simulations, while at 500 K qualitative\ndifferences between the two modeling approaches are found."
    },
    {
        "anchor": "Morphology of supported polymer electrolyte ultra-thin films: a\n  numerical study: Morphology of polymer electrolytes membranes (PEM), e.g., Nafion, inside PEM\nfuel cell catalyst layers has significant impact on the electrochemical\nactivity and transport phenomena that determine cell performance. In those\nregions, Nafion can be found as an ultra-thin film, coating the catalyst and\nthe catalyst support surfaces. The impact of the hydrophilic/hydrophobic\ncharacter of these surfaces on the structural formation of the films has not\nbeen sufficiently explored yet. Here, we report about Molecular Dynamics\nsimulation investigation of the substrate effects on the ionomer ultra-thin\nfilm morphology at different hydration levels. We use a mean-field-like model\nwe introduced in previous publications for the interaction of the hydrated\nNafion ionomer with a substrate, characterized by a tunable degree of\nhydrophilicity. We show that the affinity of the substrate with water plays a\ncrucial role in the molecular rearrangement of the ionomer film, resulting in\ncompletely different morphologies. Detailed structural description in different\nregions of the film shows evidences of strongly heterogeneous behavior. A\nqualitative discussion of the implications of our observations on the PEMFC\ncatalyst layer performance is finally proposed.",
        "positive": "Embedding theory in ML toward real-time tracking of structural dynamics\n  through hyperspectral datasets: In-situ Electron Energy Loss Spectroscopy (EELS) is an instrumental technique\nthat has traditionally been used to understand how the choice of materials\nprocessing has the ability to change local structure and composition. However,\nmore recent advances to observe and react to transient changes occurring at the\nultrafast timescales that are now possible with EELS and Transmission Electron\nMicroscopy (TEM) will require new frameworks for characterization and analysis.\nWe describe a machine learning (ML) framework for the rapid assessment and\ncharacterization of in operando EELS Spectrum Images (EELS-SI) without the need\nfor many labeled training datapoints as typically required for deep learning\nclassification methods. By embedding computationally generated structures and\nexperimental datasets into an equivalent latent space through Variational\nAutoencoders (VAE), we effectively predict the structural changes at latency\nscales relevant to closed-loop processing within the TEM. The framework\ndescribed in this study is a critical step in enabling automated, on-the-fly\nsynthesis and characterization which will greatly advance capabilities for\nmaterials discovery and precision engineering of functional materials at the\natomic scale."
    },
    {
        "anchor": "Gate-controlled ultraviolet photo-etching of graphene edges: The chemical reactivity of graphene under ultraviolet (UV) light irradiation\nis investigated under positive and negative gate electric fields. Graphene\nedges are selectively etched when negative gate voltages are applied, while the\nreactivity is significantly suppressed for positive gate voltages. Oxygen\nadsorption onto graphene is significantly affected by the Fermi level of the\nfinal state achieved during previous electrical measurements. UV irradiation\nafter negative-to-positive gate sweeps causes predominant oxygen desorption,\nwhile UV irradiation after gate sweeps in the opposite direction causes etching\nof graphene edges.",
        "positive": "Carrier Transport at the Metal-MoS2 Interface: This study illustrates the nature of electronic transport and its transition\nfrom one mechanism to another between a metal electrode and MoS2 channel\ninterface in a field effect transistor (FET) device. Interestingly,\nmeasurements of the contact resistance (Rc) as a function of temperature\nindicate a transition in the carrier transport across the energy barrier from a\nthermionic emission at a high temperature to tunneling at a low temperature.\nFurthermore, at a low temperature, the nature of the tunneling behavior is\nascertained by the current-voltage dependency that helps us feature direct\ntunneling at a low bias and Fowler-Nordheim tunneling at a high bias for a\nPd-MoS2 contact due to the effective barrier shape modulation by biasing. In\ncontrast, only direct tunneling is observed for a Cr-MoS2 contact over the\nentire applied bias range. In addition, simple analytical calculations were\ncarried out to extract Rc at the gating range, and the results are consistent\nwith the experimental data. Our results describe the transition in carrier\ntransport mechanisms across a metal-MoS2 interface, and this information\nprovides guidance for the design of future flexible, transparent electronic\ndevices based on 2-dimensional materials."
    },
    {
        "anchor": "Investigating the CVD synthesis of graphene on Ge(100): towards layer by\n  layer growth: Germanium is emerging as the substrate of choice for the growth of graphene\nin CMOS-compatible processes. For future application in next generation devices\nthe accurate control over the properties of high-quality graphene synthesized\non Ge surfaces, such as number of layers and domain size, is of paramount\nimportance. Here we investigate the role of the process gas flows on the CVD\ngrowth of graphene on Ge(100). The quality and morphology of the deposited\nmaterial is assessed by using microRaman spectroscopy, x-ray photoemission\nspectroscopy, scanning electron and atomic force microscopies. We find that by\nsimply varying the carbon precursor flow different growth regimes - yielding to\ngraphene nanoribbons, graphene monolayer and graphene multilayer - are\nestablished. We identify the growth conditions yielding to a layer-by-layer\ngrowth regime and report on the achievement of homogeneous monolayer graphene\nwith an average intensity ratio of 2D and G bands in the Raman map larger than\n3.",
        "positive": "Oxides in an oxygen potential gradient: coupled morphological stability\n  of the multiple phase boundaries: In materials that are exposed to thermodynamic potential gradients, i.e.,\ngradients of chemical potentials, electrical potential, temperature, or\npressure, transport processes of the mobile components occur. These transport\nprocesses and the coupling between different processes are not only of\nfundamental interest, but are also the origin of several degradation processes,\nsuch as kinetic unmixing and decomposition. In addition, changes in the\nmorphology of the material surfaces and interfaces may appear. In this paper, a\ncomprehensive formal treatment of the coupled morphological stability of\nmultiple phase boundaries will be given for oxides that are exposed to an\noxygen potential gradient."
    },
    {
        "anchor": "Strain dependent elastic modulus of graphene: Indentation experiments on graphene membranes pre-stressed by hydrostatic\npressure show an increase in effective elastic modulus from 300 N/m in non\npressurized membranes to 700 N/m for pre-strains above 0.5 %. This pronounced\ndependence of the stiffness of graphene with strain is attributed to its high\nanharmonicity and the great influence of out of plane corrugations of this\natomic thick membrane in its mechanical properties. Our experimental findings\nimply that graphene measured stiffness is highly influenced by the presence of\ncorrugations and that the in plane elastic modulus corresponding to atomic bond\nstretching is more akin to 700 N/m, instead of the commonly accepted 340 N/m.",
        "positive": "Magnetic transition in Ni-Pt alloy Systems : Experiment and Theory: We report here the preparation and measurements on the susceptibility, sound\nvelocity and internal friction for Ni-Pt systems. We then compare these\nexperimental results with the first principle theoretical predictions and show\nthat there is reasonable agreement with experiment and theory."
    },
    {
        "anchor": "Substrate engineering in the growth of perovskite crystals: Metal halide perovskites have recently emerged as promising materials for the\nnext generation of optoelectronic devices owing to their remarkable intrinsic\nproperties. In the growth of perovskite crystals, the substrates are essential\nand play a vital role. Herein, substrate engineering in the growth of\nperovskite crystals have been reviewed. Particularly, various modified\nstrategies and corresponding mechanism based on the substrate engineering\napplied to the optimization of thickness, nucleation and growth rate are\nhighlighted. Then the alterable adhesion to substrates will also be discussed.\nFurthermore, applying the structural coherence of epitaxial crystals with\nsubstrate, scalable perovskite single-crystalline thin films have been obtained\nand can be transferred onto arbitrary substrates. Substrate engineering also\ncan stabilize the desired perovskite phases by modulating the strain between\ncrystals and substrates. Finally, several key challenges and related solutions\nin the growth of perovskite crystals based on substrate engineering are\nproposed. This review aims to guide the future of substrate engineering in\nperovskite crystals for various optoelectronic applications.",
        "positive": "Operando pair distribution function analysis of nanocrystalline\n  functional materials: the case of $\\mathrm{TiO_{2}}$-bronze nanocrystals in\n  Li-ion battery electrodes: Structural modelling of $operando$ pair distribution function (PDF) data of\nfunctional materials can be highly complex. To aid the understanding of complex\noperando PDF data, we here demonstrate a toolbox for PDF analysis. The tools\ninclude the structureMining, similarityMapping, nmfMapping apps available\nthrough the online service 'PDF in the cloud' (PDFitc, www.pdfitc.org), as well\nas noise-filtering using principal component analysis (PCA). The tools are\napplied to both ex situ and operando PDF data for 3 nm\n$\\mathrm{TiO_{2}}$-bronze nanocrystals, which function as the active electrode\nmaterial in a Li-ion battery. The tools enable structural modelling of the ex\nsitu and operando PDF data, revealing two pristine $\\mathrm{TiO_{2}}$ phases\n(bronze and anatase) and two lithiated $\\mathrm{Li_{x}TiO_{2}}$ phases\n(lithiated versions of bronze and anatase), and the phase evolution during\nGalvanostatic cycling is characterized."
    },
    {
        "anchor": "Magnetocaloric functional properties of $Sm_{0.6}Sr_{0.4}MnO_3$\n  manganite due to advanced nanostructured morphology: The magnetocaloric effect (MCE) is the key concept to produce new, advanced,\nfreon-like free, low cost and environmental friendly magnetic refrigerators.\nAmong several potential materials, $Sm_{0.6}Sr_{0.4}MnO_3$ manganite presents\none of the highest MCE value in comparison to all other known manganites;\nhowever, its studied was only concentrated on the bulk material. To overcame\nthis lack of the information we successfully produced advanced nanostructures,\nnamely nanoparticles and nanotubes of that highlighted manganite by using a\nsol-gel modified method. High resolution transmission electron microscopy\nrevealed nanoparticle and nanotube diameters of 29 nm and 200 nm, respectively;\nand, in addition, this technique also showed that the wall of the nanotube is\nformed by the nanoparticles with 25 nm of diameter. The magnetocaloric\npotentials, ${\\Delta}S_M$ versus T curves, of the nanostructures were obtained\nand they are broader than the their bulk counterpart. This increases the useful\ntemperature range of a magnetic refrigerator. But also an undesired M-shape\nprofile for the nanotube sample was observed, due to the rising of a\nsuperparamagnetic behavior. These results also evidenced the existence of a\nnanoparticle size threshold below which the advantage to make the transition\nwider is no longer valid.",
        "positive": "Enhanced carrier mobility in anisotropic 2D tetrahex-carbon through\n  strain engineering: A recently predicted two dimensional (2D) carbon allotrope, tetrahex-carbon\nconsisting of tetragonal and hexagonal rings, draws research interests due to\nits unique mechanical and electronic properties. Tetrahex-C shows ultrahigh\nstrength, negative Poisson ratio, a direct band gap and high carrier mobility.\nIn this work, we employ first-principles density-functional theory calculations\nto explore the directional dependence of electronic properties such as carrier\neffective mass and mobility in tetrahex-C. Tetrahex-C demonstrates strong\nanisotropicity in effective mass of charge carrier and therefore its mobility\n(electric conductance) exhibits a strong orientation preference. More\ninteresting, we find that such unique anisotropic carrier effective mass and\nmobility can be controlled by simple uniaxial strain. The orientation\ndependence of effective mass can be dramatically rotated by 90 degrees through\napplying uniaxial tensile strain beyond ~ 7% (11%) in the armchair direction\nfor the hole (electron). As a result, the intrinsic carrier mobility in\ntetrahex-C is significantly enhanced. The results are useful for potential\nelectronic and mechanical applications in tetrahex-C."
    },
    {
        "anchor": "A detailed analysis of dipolar interactions and analytical\n  approximations in arrays of magnetic nanowires: The investigation of the role of interactions in magnetic wire arrays is\ncomplex and often subject to strong simplifications. In this paper we obtained\nanalytical expressions for the magnetostatic interactions between wires and\ninvestigate the range of validity of dipole-dipole, first order and second\norder approximations. We also analyze the extension of the interwire\nmagnetostatic interactions in a sample and found that the number of wires\nrequired to reach energy convergence in the array strongly depends on the\nrelative magnetic orientation between the wires.",
        "positive": "Investigating the effects of smoothness of interfaces on stability of\n  probing nano-scale thin films by neutron reflectometry: Most of the reflectometry methods which are used for determining the phase of\ncomplex reflection coefficient such as reference method and Variation of\nSurroundings medium are based on solving the Schr\\\"odinger equation using a\ndiscontinuous and step-like scattering optical potential. However, during the\ndeposition process for making a real sample the two adjacent layers are mixed\ntogether and the interface would not be discontinuous and sharp. The smearing\nof adjacent layers at the interface (smoothness of interface), would affect the\nreflectivity, phase of reflection coefficient and reconstruction of the\nscattering length density (SLD) of the sample. In this paper, we have\ninvestigated the stability of reference method in the presence of smooth\ninterfaces. The smoothness of interfaces is considered by using a continuous\nfunction scattering potential. We have also proposed a method to achieve the\nmost reliable output result while retrieving the SLD of the sample."
    },
    {
        "anchor": "The phase stability of large-size nanoparticle alloy catalysts at ab\n  initio quality using a nearsighted force-training approach: CoPt nanoparticle catalysts are integral to commercial fuel cells. Such\nsystems are prohibitive to fully characterize with electronic structure\ncalculations. Machine-learned potentials offer a scalable solution; however,\nsuch potentials are only reliable if representative training data can be\nemployed, which typically requires large electronic structure calculations.\nHere, we use the nearsighted-force training approach to make high-fidelity\nmachine-learned predictions on large nanoparticles with $>$5,000 atoms using\nonly systematically generated small structures ranging from 38-168 atoms. The\nresulting ensemble model shows good accuracy and transferability in describing\nrelative energetics for CoPt nanoparticles with various shapes, sizes and Co\ncompositions. It is found that the fcc(100) surface is more likely to form a\nL1$_0$ ordered structure than the fcc(111) surface. The energy convex hull of\nthe icosahedron shows the most stable particles have Pt-rich skins and Co-rich\nunderlayers. Although the truncated octahedron is the most stable shape across\nall sizes of Pt nanoparticles, a crossover to icosahedron exists due to a large\ndownshift of surface energy for CoPt nanoparticle alloys. The downshift can be\nattributed to strain release on the icosahedron surface due to Co alloying. We\nintroduced a simple empirical model to describe the role of Co alloying in the\ncrossover for CoPt nanoparticles. With Monte-Carlo simulations we additionally\nsearched for the most stable atomic arrangement for a truncated octahedron with\nequal Pt and Co compositions, and also we studied its order-disorder phase\ntransition. We validated the most stable configurations with a new highly\nscalable density functional theory code called SPARC. Lastly, the\norder-disorder phase transition for a CoPt nanoparticle exhibits a lower\ntransition temperature and a smoother transition, compared to the bulk CoPt\nalloy.",
        "positive": "The role of thermalisation in hot carrier cooling dynamics: The hot carrier solar cell (HCSC) concept has been proposed to overcome the\nShockley Queisser limit of a single p-n junction solar cell by harvesting\ncarriers before they have lost their surplus energy. A promising family of\nmaterials for these purposes is metal halide perovskites (MHP). MHPs have\nexperimentally shown very long cooling times, the key requirement of a HCSC. By\nusing Ensemble Monte Carlo (EMC) simulations we shed light on why cooling times\nare found to be extended for these materials. In this manuscript, we\nconcentrate on the role of thermalisation in the cooling process. We specify\nthe role of electron-phonon and electron-electron interactions in\nthermalisation and cooling, while furthermore showing how these processes\ndepends on several relevant material parameters, such as the dielectric\nconstant and the effective mass. Finally, we quantify how thermalisation can\nalso act as a cooling mechanism via the cold background effect. Here, we stress\nthe importance of a low degree of background doping in order to achieve the\nobserved extended cooling times. This work provides insights into the ongoing\ndiscussion on cooling times in MHPs. In addition our results are an important\naddition to the debate on whether or not tin perovskites are suitable\ncandidates for HCSCs."
    },
    {
        "anchor": "Self-sealing complex oxide resonators: Although 2D materials hold great potential for next-generation pressure\nsensors, recent studies revealed that gases permeate along the membrane-surface\ninterface that is only weakly bound by van der Waals interactions,\nnecessitating additional sealing procedures. In this work, we demonstrate the\nuse of free-standing complex oxides as self-sealing membranes that allow the\nreference cavity of pressure sensors to be sealed by a simple anneal. To test\nthe hermeticity, we study the gas permeation time constants in nano-mechanical\nresonators made from SrRuO3 and SrTiO3 membranes suspended over SiO2/Si\ncavities which show an improvement up to 4 orders of magnitude in the\npermeation time constant after annealing the devices for 15 minutes. Similar\ndevices fabricated on Si3N4/Si do not show such improvements, suggesting that\nthe adhesion increase over SiO2 is mediated by oxygen bonds that are formed at\nthe SiO2/complex oxide interface during the self-sealing anneal. We confirm the\nenhancement of adhesion by picosecond ultrasonics measurements which show an\nincrease in the interfacial stiffness by 70% after annealing. Since it is\nstraigthforward to apply, the presented self-sealing method is thus a promising\nroute toward realizing ultrathin hermetic pressure sensors.",
        "positive": "Electronic Transport Properties of Quasicrystalline Thin Films: Quasicrystals are assumed to be electronically stabilized by a Hume-Rothery\ntype mechanism. This explains most of the peculiar properties of quasicrystals.\nThe stabilization is investigated by electronic transport properties, as they\ndepend sensitively on the stabilizing interaction between the static structure\nand the conduction electrons. Thin-film techniques provide samples which are\nwell suited for systematic investigations as a function of composition and\nstructural quality for Al-Cu-Fe and Al-Pd-Re i-phases. For a narrow range of\ncomposition, large transport anomalies occur, reaching a\nmetal-insulator-transition in thin films of i-Al-Pd-Re. We discuss this in the\nframework of a resonant scattering of the conduction electrons with the\nquasicrystalline structure, leading to a reduced electronic mobility and\ndensity of states (DOS) at the Fermi energy $E_F$."
    },
    {
        "anchor": "Giant spin Hall effect in half-Heusler alloy topological semimetal YPtBi\n  grown at low temperature: Half-Heusler alloy topological semimetal YPtBi is a promising candidate for\nan efficient spin source material having both large spin Hall angle\n${\\theta}$$_{SH}$ and high thermal stability. However, high-quality YPtBi thin\nfilms with low bulk carrier density are usually grown at 600${\\deg}$C, which\nexceeds the limitation of 400${\\deg}$C for back end of line (BEOL) process.\nHere, we investigate the crystallinity and spin Hall effect of YPtBi thin films\ngrown at lower growth temperature down to 300${\\deg}$C. Although\n${\\theta}$$_{SH}$ degraded with lowering the growth temperature to 300${\\deg}$C\ndue to degradation of the crystallinity, it was recovered by reducing the\nsputtering Ar gas pressure. We achieved a giant ${\\theta}$$_{SH}$ up to 8.2 and\ndemonstrated efficient spin-orbit torque magnetization switching by ultralow\ncurrent density of ~10$^5$ A/cm$^2$ in YPtBi grown at 300${\\deg}$C with the Ar\ngas pressure of 1 Pa. Our results provide the recipe to achieve giant\n${\\theta}$$_{SH}$ in YPtBi grown at lower growth temperature suitable for BEOL\nprocess.",
        "positive": "Surface Restructuring of Nickel Sulfide Generates Optimally-Coordinated\n  Active Sites for ORR Catalysis: First-row transition metal oxides and chalcogenides have been found to rival\nthe performance of precious metal-based catalysts for the interconversion of\nwater and O$_2$. The high lability of the first-row transition metal ions leads\nto surface dynamics under the conditions of catalysis and results in active\nsite structures distinct from those expected by surface termination of the bulk\nlattice. While these surface transformations have been well-characterized on\nmany metal oxides, the surface dynamics of heavier chalcogenides under\nelectrocatalytic conditions are largely unknown. We recently reported that the\nheazlewoodite Ni$_3$S$_2$ bulk phase supports efficient ORR catalysis under\nbenign aqueous conditions and exhibits excellent tolerance to electrolyte\nanions such as phosphate which poison Pt. Herein, we combine electrochemistry,\nsurface spectroscopy and high resolution microscopy to characterize the surface\ndynamics of Ni$_3$S$_2$ under ORR catalytic conditions. We show that\nNi$_3$S$_2$ undergoes self-limiting oxidative surface restructuring to form an\napproximately 2 nm amorphous surface film conformally coating the Ni$_3$S$_2$\ncrystallites. The surface film has a nominal NiS stoichiometry and is highly\nactive for ORR catalysis. Using DFT calculations we show that, to a first\napproximation, the catalytic activity of nickel sulfides is determined by the\nNi-S coordination numbers at surface exposed sites through a simple geometric\ndescriptor. In particular, we find that the surface sites formed dynamically on\nthe surface of amorphous NiS during surface restructuring provide an optimal\nenergetic landscape for ORR catalysis. This work provides a systematic\nframework for characterizing the rich surface chemistry of metal-chalcogenides\nand provides principles for developing a broader understanding of\nelectrocatalysis mediated by amorphous materials."
    },
    {
        "anchor": "Structural reorientation and compaction of porous MoS2 coatings during\n  wear testing: Industrial upscaling frequently results in a different coating microstructure\nthan the laboratory prototypes presented in the literature. Here, we\ninvestigate the wear behavior of physical vapor deposited (PVD) MoS2 coatings:\nA dense, nanocrystalline MoS2 coating, and a porous, prismatic-textured MoS2\ncoating. Transmission electron microscopy (TEM) investigations before and after\nwear testing evidence a crystallographic reorientation towards a basal texture\nin both samples. A basal texture is usually desirable due to its low-friction\nproperties. This favorable reorientation is associated to a tribological\ncompaction of the porous specimens. Following running-in, sliding under high\ncontact pressure ultimately leads to a wear rate as small as for an ideal grown\nbulk MoS2 single crystal grown by chemical vapor deposition (CVD). This\nsuggests that the imperfections of industrial grade MoS2 coatings can be\nremediated by a suitable pretreatment.",
        "positive": "Molecular-dynamics simulations of stacking-fault-induced dislocation\n  annihilation in pre-strained ultrathin single-crystalline copper films: We report results of large-scale molecular-dynamics (MD) simulations of\ndynamic deformation under biaxial tensile strain of pre-strained\nsingle-crystalline nanometer-scale-thick face-centered cubic (fcc) copper\nfilms. Our results show that stacking faults, which are abundantly present in\nfcc metals, may play a significant role in the dissociation, cross-slip, and\neventual annihilation of dislocations in small-volume structures of fcc metals.\nThe underlying mechanisms are mediated by interactions within and between\nextended dislocations that lead to annihilation of Shockley partial\ndislocations or formation of perfect dislocations. Our findings demonstrate\ndislocation starvation in small-volume structures with ultra-thin film\ngeometry, governed by a mechanism other than dislocation escape to free\nsurfaces, and underline the significant role of geometry in determining the\nmechanical response of metallic small-volume structures."
    },
    {
        "anchor": "Effect of 2 MeV Fe3+ irradiation on Fe atom site population in a\n  sigma-phase Fe-Cr compound: A sigma-Fe54.5Cr45.5 samples irradiated in vacuum with 2 MeV Fe3+ ions at\n300, 400, 475 and 700 deg C to the maximum dose of 12.5 dpa were studied with\nthe conversion electron M\\\"ossbauer spectroscopy (CEMS). The analysis of the\nroom temperature CEMS spectra revealed an irradiation-induced redistribution of\nFe atoms viz. their number on B and D sites decreased while on A, C and E sites\nincreased. The degree of the redistribution was found to be proportional to the\nnumber of Fe atoms present on the lattice sites in the non-irradiated samples.\nThe highest degree of the redistribution was revealed in the sample irradiated\nat 300 deg C. No change in the site occupancy was found in the sample\nirradiated at 700 deg C.",
        "positive": "Linear temperature behavior of thermopower and strong electron-electron\n  scattering in thick F-doped SnO$_{2}$ films: Both the semi-classical and quantum transport properties of F-doped SnO$_2$\nthick films ($\\sim$1\\,$\\mu$m) were investigated experimentally. It is found\nthat the resistivity caused by the thermal phonons obeys Bloch-Gr\\\"{u}neisen\nlaw from $\\sim$90 to 300\\,K, while only the diffusive thermopower, which varies\nlinearly with temperature from 300 down to 10\\,K, can be observed.The\nphonon-drag thermopower is completely suppressed due to the long\nelectron-phonon relaxation time in the compound. These observations, together\nwith the temperature independent characteristic of carrier concentration,\nindicate that the conduction electron in F-doped SnO$_2$ films behaves\nessentially like a free electron. At low temperatures, the electron-electron\nscattering dominates over the electron-phonon scattering and governs the\ninelastic scattering process. The theoretical predicated scattering rates for\nboth large- and small-energy-transfer electron-electron scattering processes,\nwhich are negligibly weak in three-dimensional disordered conventional\nconductors, are quantitatively tested in this lower carrier concentration and\nfree-electron-like highly degenerate semiconductor."
    },
    {
        "anchor": "Bloch-to-N\u00e9el domain wall transition evinced through morphology of\n  magnetic bubble expansion in Ta/CoFeB/MgO layers: Ta/CoFeB/MgO trilayers with perpendicular magnetic anisotropy are often\ncharacterised by vanishing or modest values of interfacial\nDzyaloshinskii-Moriya interaction (DMI), which results in purely Bloch or mixed\nBloch-N\\'eel domain walls (DWs). Here we investigate the creep evolution of the\noverall magnetic bubble morphology in these systems under the combined presence\nof in-plane and out-of-plane magnetic fields and we show that He$^+$ ion\nirradiation induces a transition of the internal DW structure towards a fully\nN\\'eel spin texture. This transition can be correlated to a simultaneous\nincrease in DMI strength and reduction in saturation magnetisation -- which are\na direct consequence of the effects of ion irradiation on the bottom and top\nCoFeB interfaces, respectively. The threshold irradiation dose above which DWs\nacquire a pure N\\'eel character is experimentally found to be between 12\n$\\times$ 10$^{18}$ He$^+$/m$^2$ and 16 $\\times$ 10$^{18}$ He$^+$/m$^2$,\nmatching estimations from the one dimensional DW model based on material\nparameters. Our results indicate that evaluating the global bubble shape during\nits expansion can be an effective tool to sense the internal bubble DW\nstructure. Furthermore, we show that ion irradiation can be used to achieve\npost-growth engineering of a desired DW spin texture.",
        "positive": "Anisotropic transport and Negative Resistance in a polycrystalline\n  metal-semiconductor (Ni-TiO2) hybrid: We investigate anomalous electrical transport properties of a Ni-TiO2 hybrid\nsystem displaying a unique nanostructured morphology. The system undergoes an\ninsulator to metal transition below 150 K with a low temperature metallic phase\nthat shows negative resistance in a four-probe configuration. Temperature\ndependent transport measurements and numerical modelling show that the\nanomalies originate from the dendritic architecture of the TiO2 backbone\ninterspersed with Ni nanoparticles that paradoxically renders this\npolycrystalline, heterogeneous system highly anisotropic. The study critiques\ninferences that may be drawn from four-probe transport measurements and offers\nvaluable insights into modelling conductivity of anisotropic hybrid materials."
    },
    {
        "anchor": "Peierls distortion, magnetism, and high hardness of manganese\n  tetraboride: We report crystal structure, electronic structure, and magnetism of manganese\ntetraboride, MnB4, synthesized under high-pressure high-temperature conditions.\nIn contrast to superconducting FeB4 and metallic CrB4, which are both\northorhombic, MnB4 features a monoclinic crystal structure. Its lower symmetry\noriginates from a Peierls distortion of the Mn chains. This distortion nearly\nopens the gap at the Fermi level, but despite the strong dimerization and the\nproximity of MnB4 to the insulating state, we find indications for a sizable\nparamagnetic effective moment of about 1.7 muB/f.u., ferromagnetic spin\ncorrelations and, even more surprisingly, a prominent electronic contribution\nto the specific heat. However, no magnetic order has been observed in standard\nthermodynamic measurements down to 2 K. Altogether, this renders MnB4 a\nstructurally simple but microscopically enigmatic material; we argue that its\nproperties may be influenced by electronic correlations.",
        "positive": "Optical Absorption Spectra and Excitons of Dye-Substrate Interfaces:\n  Catechol on TiO$_2$(110): Optimizing the photovoltaic efficiency of dye-sensitized solar cells (DSSC)\nbased on staggered gap heterojunctions requires a detailed understanding of\nsub-band gap transitions in the visible from the dye directly to the\nsubstrate's conduction band (CB) (type-II DSSCs). Here, we calculate the\noptical absorption spectra and spatial distribution of bright excitons in the\nvisible region for a prototypical DSSC, catechol on rutile TiO$_2$(110), as a\nfunction of coverage and deprotonation of the OH anchoring groups. This is\naccomplished by solving the Bethe-Salpeter equation (BSE) based on hybrid\nrange-separated exchange and correlation functional (HSE06) density functional\ntheory (DFT) calculations. Such a treatment is necessary to accurately describe\nthe interfacial level alignment and the weakly bound charge transfer\ntransitions that are the dominant absorption mechanism in type-II DSSCs. Our\nHSE06 BSE spectra agree semi-quantitatively with spectra measured for catechol\non anatase TiO$_2$ nanoparticles. Our results suggest deprotonation of\ncatechol's OH anchoring groups, while being nearly isoenergetic at high\ncoverages, shifts the onset of the absorption spectra to lower energies, with a\nconcomitant increase in photovoltaic efficiency. Further, the most relevant\nbright excitons in the visible region are rather intense charge transfer\ntransitions with the electron and hole spatially separated in both the [110]\nand [001] directions. Such detailed information on the absorption spectra and\nexcitons is only accessible via periodic models of the combined dye-substrate\ninterface."
    },
    {
        "anchor": "Monoclinic and triclinic phases in higher-order Devonshire theory: Devonshire theory provides a successful phenomenological description of many\ncubic perovskite ferroelectrics such as BaTiO3 via a sixth-order expansion of\nthe free energy in the polar order parameter. However, the recent discovery of\na novel monoclinic ferroelectric phase in the PZT system by Noheda et al.\n(Appl. Phys. Lett. 74, 2059 (1999)) poses a challenge to this theory. Here, we\nconfirm that the sixth-order Devonshire theory cannot support a monoclinic\nphase, and consider extensions of the theory to higher orders. We show that an\neighth-order theory allows for three kinds of equilibrium phases in which the\npolarization is confined not to a symmetry axis but to a symmetry plane. One of\nthese phases provides a natural description of the newly observed monoclinic\nphase. Moreover, the theory makes testable predictions about the nature of the\nphase boundaries between monoclinic, tetragonal, and rhombohedral phases. A\nferroelectric phase of the lowest (triclinic) symmetry type, in which the\npolarization is not constrained by symmetry, does not emerge until the\nDevonshire theory is carried to twelfth order. A topological analysis of the\ncritical points of the free-energy surface facilitates the discussion of the\nphase transition sequences.",
        "positive": "Simulated ion-sputtering and Auger electron spectroscopy depth profiling\n  study of intermixing in Cu/Co: The ion-bombardment induced evolution of intermixing is studied by molecular\ndynamics simulations and by Auger electron spectroscopy depth profiling\nanalysis (AESD) in Cu/Co multilayer. It has been shown that from AESD we can\nderive the low-energy mixing rate and which can be compared with the simulated\nvalues obtained by molecular dynamics (MD) simulations.The overall agreement is\nreasonably good hence MD can hopefully be used to estimate the rate of\nintermixing in various interface systems."
    },
    {
        "anchor": "Why twisting angles are diverse in graphene Moire patterns?: The interlayer energy of the twisting bilayer graphene is investigated by the\nmolecular mechanics method using both the registry-dependent potential and the\nLennard-Jones potential. Both potentials show that the interlayer energy is\nindependent of the twisting angle $\\theta$, except in the two boundary regions\n$\\theta\\approx 0$ or $60^{\\circ}$, where the interlayer energy is proportional\nto the square of the twisting arc length. The calculation results are\nsuccessfully interpreted by a single atom model. An important information from\nour findings is that, from the energy point of view, there is no preference for\nthe twisting angle in the experimental bilayer graphene samples, which actually\nexplains the diverse twisting angles in the experiment.",
        "positive": "Use of Self-assembled Plasmonic Hole Arrays on AlGaAs/GaAs 2DEG for\n  Large Area Terahertz Applicaton: Plasmonic detectors have the potential to provide a method of rapid\nspectroscopy without the need of moving mirrors or gratings. Previous\nmeasurements have demonstrated frequency tunable detection based on plasmonic\nexcitations, however these devices were either small area, polarization\ndependent and/or required e-beam lithography. We demonstrate that large area\nhigh sensitivity THz plasmonic detection can be achieved using self-assembly\nnanosphere lithography. We achieve a submicron feature size grid covering a\ndetector area of 4 mm^2. Measurements at 80 K show a large transmission change\nof 25% and a blue shift with decreasing aperture size due to coupling of disk\nlattice. The resonant frequencies of our device are function of radius, not\nperiodicity. We also confirmed a magneto plasmon dispersion of the device. In\nconclusion we find that fabrication of self-assembled grids is a rapid and\nreliable method for plasmonic devices in the terahertz range."
    },
    {
        "anchor": "Strain-induced Isostructural and Magnetic Phase Transitions in Monolayer\n  MoN$_2$: The change of bonding status, typically occurring only in chemical processes,\ncould dramatically alter the material properties. Here, we show that a tunable\nbreaking and forming of a diatomic bond can be achieved through physical means,\ni.e., by a moderate biaxial strain, in the newly discovered MoN$_2$\ntwo-dimensional (2D) material. Based on first-principles calculations, we\npredict that as the lattice parameter is increased under strain, there exists\nan isostructural phase transition at which the N-N distance has a sudden drop,\ncorresponding to the transition from a N-N nonbonding state to a N-N single\nbond state. Remarkably, the bonding change also induces a magnetic phase\ntransition, during which the magnetic moments transfer from the N(2p)\nsublattice to the Mo(4d) sublattice, meanwhile the type of magnetic coupling is\nchanged from ferromagnetic to anti-ferromagnetic. We provide a physical picture\nfor understanding these striking effects. The discovery is not only of great\nscientific interest in exploring unusual phase transitions in low-dimensional\nsystems, but it also reveals the great potential of the 2D MoN$_2$ material in\nthe nanoscale mechanical, electronic, and spintronic applications.",
        "positive": "Linear aspects of the KKR formalism: We present one-dimensional KKR method with the aim to elucidate its linear\nfeatures, particularly important in optimizing the numerical algorithms in\nenergy bands computations. The conventional KKR equations based on the multiple\nscattering theory as well as novel forms of the secular matrix with nearly\nlinear energy dependency of the eigenvalues are presented. The quasi-linear\nbehaviour of these eigenvalue functions appears after (i) re-normalizing the\nwave functions in such a way that 'irregular' solutions vanish on the boundary\nof the 'muffin-tin' segments and (ii) integrating the full Green function over\nthe whole Wigner-Seitz cell. In addition, using the aforementioned approach we\nderive one-dimensional analog of the generalized Lloyd formula.\n  The novel KKR approach illustrated in one-dimension can be almost directly\napplied to the higher dimensional cases. This should open prospects for the\naccurate KKR band structure computations of very complex materials."
    },
    {
        "anchor": "Light-induced weak ferromagnetism through nonlinear magnonic\n  rectification: Rectification describes the generation of a quasistatic component from an\noscillating field, such as an electric polarization in optical rectification,\nor a structural distortion in nonlinear phononic rectification. Here, we\npresent a third fundamental process for magnetization, in which spin precession\nis rectified along the coordinates of a nonlinearly driven magnon mode in an\nantiferromagnet. We demonstrate theoretically that a quasistatic magnetization\ncan be induced by transient spin canting in response to the coherent excitation\nof a chiral phonon mode that produces an effective magnetic field for the\nspins. This mechanism, which we call nonlinear magnonic rectification, is\ngenerally applicable to magnetic systems that exhibit infrared-active chiral\nphonon modes. Our results serve as an example of light-induced weak\nferromagnetism and open a promising avenue towards creating dynamical spin\nconfigurations that are not accessible in equilibrium.",
        "positive": "Fully Self-Consistent Finite-Temperature $GW$ in Gaussian Bloch Orbitals\n  for Solids: We present algorithmic and implementation details for the fully\nself-consistent finite-temperature $GW$ method in Gaussian Bloch orbitals for\nsolids. Our implementation is based on the finite-temperature Green's function\nformalism in which all equations are solved on the imaginary axis, without\nresorting to analytical continuation during the self-consistency. No\nquasiparticle approximation is employed and all matrix elements of the\nself-energy are explicitly evaluated. The method is tested by evaluating the\nband gaps of selected semiconductors and insulators. We show agreement with\nother, differently formulated finite-temperature sc$GW$ implementations when\nfinite-size corrections and basis set errors are taken into account. By\nmigrating computationally intensive calculations to GPUs, we obtain scalable\nresults on large supercomputers with nearly optimal performance. Our work\ndemonstrates the applicability of Gaussian orbital based sc$GW$ for $\\emph{ab\ninitio}$ correlated materials simulations and provides a sound starting point\nfor embedding methods built on top of $GW$."
    },
    {
        "anchor": "Kohn-Sham decomposition in real-time time-dependent density-functional\n  theory: An efficient tool for analyzing plasmonic excitations: The real-time-propagation formulation of time-dependent density-functional\ntheory (RT-TDDFT) is an efficient method for modeling the optical response of\nmolecules and nanoparticles. Compared to the widely adopted linear-response\nTDDFT approaches based on, e.g., the Casida equations, RT-TDDFT appears,\nhowever, lacking efficient analysis methods. This applies in particular to a\ndecomposition of the response in the basis of the underlying single-electron\nstates. In this work, we overcome this limitation by developing an analysis\nmethod for obtaining the Kohn-Sham electron-hole decomposition in RT-TDDFT. We\ndemonstrate the equivalence between the developed method and the Casida\napproach by a benchmark on small benzene derivatives. Then, we use the method\nfor analyzing the plasmonic response of icosahedral silver nanoparticles up to\nAg$_{561}$. Based on the analysis, we conclude that in small nanoparticles\nindividual single-electron transitions can split the plasmon into multiple\nresonances due to strong single-electron-plasmon coupling whereas in larger\nnanoparticles a distinct plasmon resonance is formed.",
        "positive": "A Hybrid Machine Learning Framework for Predicting Hydrogen Storage\n  Capacities: Unsupervised Feature Learning with Deep Neural Networks: In this study, we present a sophisticated hybrid machine-learning framework\nthat significantly improves the accuracy of predicting hydrogen storage\ncapacities in metal hydrides. This is a critical challenge due to the scarcity\nof experimental data and the complexity of high-dimensional feature spaces. Our\napproach employs the power of unsupervised learning through the use of a\nstate-of-the-art autoencoder. This autoencoder is trained on elemental\ndescriptors obtained from Mendeleev software, enabling the extraction of a\nmeaningful and lower dimensional latent space from the input data. This latent\nrepresentation serves as the basis for our deep multi-layer perceptron (MLP)\nmodel, which consists of five layers and shows good precision in predicting\nhydrogen storage capacities. Furthermore, our results show very good agreement\nwith the results of density functional theory (DFT). In addition to addressing\nthe limitations caused by limited and unevenly distributed data in the field of\nhydrogen storage materials, we also focus on discovering new materials that\nshow promising opportunities for hydrogen storage. These materials were\nidentified using both feature-based approaches and predictions generated by a\nlarge language model. Finally, our investigation into the effectiveness of\ntransferring weights from the autoencoder to the MLP, in addition to the latent\nfeatures, suggests that while this strategy slightly improves model performance\nindicated by a slightly higher R$^2$ value and lower RMSE, it emphasizes the\nintricate challenge of adapting pre-trained weights for specific supervised\ntasks."
    },
    {
        "anchor": "Trapped charge driven degradation of perovskite solar cells: Perovskite solar cells have shown fast deterioration during actual operation\neven with encapsulation, but its mechanism has been elusive. We found the\nfundamental mechanism for irreversible degradation of perovskite materials in\nwhich trapped charges regardless of the polarity play a decisive role. A novel\nexperimental setup utilizing different polarity ions revealed that the moisture\ninduced irreversible dissociation of perovskite materials is triggered by\ncharges trapped along grain boundaries. Our finding clearly explained the\nintriguing observations why light soaking induces irreversible degradation\nwhile in the dark, moisture only causes reversible hydration, and why\ndegradation begins from different side of interface for different charge\nextraction layers. The deprotonation of organic cations by trapped charge\ninduced local electric field is attributed to the initiation of irreversible\ndecomposition.",
        "positive": "Investigation of the nonlocal coherent-potential approximation: Recently the nonlocal coherent-potential approximation (NLCPA) has been\nintroduced by Jarrell and Krishnamurthy for describing the electronic structure\nof substitutionally disordered systems. The NLCPA provides systematic\ncorrections to the widely used coherent-potential approximation (CPA) whilst\npreserving the full symmetry of the underlying lattice. Here an analytical and\nsystematic numerical study of the NLCPA is presented for a one-dimensional\ntight-binding model Hamiltonian, and comparisons with the embedded cluster\nmethod (ECM) and molecular coherent potential approximation (MCPA) are made."
    },
    {
        "anchor": "Extension of the Kramers-Kronig method for polarized infrared\n  reflectance spectra from the face of low-symmetry crystals: An extension of the Kramers-Kronig method for treatment of polarized infrared\nreflectance spectra from the face of low-symmetry crystals, where directions of\nprincipal dielectric axes depend on frequency, is proposed. It is shown, how to\nobtain the frequency dependencies of the complex reflectivity tensor\ncomponents, using three reflectance spectra measured for different directions\nof linear polarization of the incident wave, when reflected wave is immediately\nsent to the detector. The problem is formulated in a form of the system of\nintegral equations, and effective numerical technique is found for solving it.\nThe question of the further recovery of the complex dielectric tensor on the\nbase of the reflectivity tensor, is discussed. The case of the monoclinic\ncrystals is considered in details. An example of the application of the\nextended Kramers-Kronig method to the reflectance spectra from the (ac)-face of\nthe single-crystal bismuth oxide with the monoclinic lattice is given.",
        "positive": "Microscopic Observation of Entangled Multi-Magnetoelectric Coupling\n  Phenomenon: Searching for new functionality in next generation electronic devices is a\nprincipal driver of material physics research. Multiferroics simultaneously\nexhibit electric and magnetic order parameters that may be coupled through\nmagnetoelectric (ME) effects. In single-phase materials the ME effect arises\nfrom one of three known mechanisms: inverse Dzyaloshinskii-Moriya (IDM)\ninteraction, spin dependent ligand-metal (p-d) orbital hybridization, and\nexchange striction. However, the coupling among these mechanisms remains\nlargely unexplored despite envisioned potential capabilities. Here, we present\ncooperative tuning between both IDM interaction and p-d hybridization that\nleads to discrete ME states in Ba0.5Sr2.5Co2Fe24O41. In-situ x-ray diffraction\nexposes the microscopic interplay between these two mechanisms, marked by a\nunique ME susceptibility upon electric and magnetic fields. The entangled\nmulti-ME coupling phenomenon observed in this room-temperature ME hexaferrite\noffers a pathway to novel functional control for ME device applications."
    },
    {
        "anchor": "Emergent Atomic Environments in Twisted Bilayer Graphene and Their Use\n  in the Prediction of the Vibrational Properties: While Bernal stacked bilayer graphene bears two distinct atom types in its\nlattice, there exists no analytical framework addressing the number of atomic\nenvironments that emerge in twisted bilayer graphene superlattices. In this\nwork, we have computationally analyzed 120 different twisted bilayer\nsuperlattices using descriptor functions to study the emergent local\nenvironments. Our study reveals that the number of atoms with unique local\nenvironments depend on the superlattice size linearly. Moreover, this linear\ndependence manifests itself on two distinct lines and this automatically\nsuggests a new classification scheme based on the local environments. As a\npossible application, the use of local environments in the investigation of\nvibrational properties is discussed with respect to the existing literature.\nMolecular dynamics simulations are performed to calculate the phonon density of\nstates of the 120 structures as well as the local phonon density of states of\ntheir individual atoms. The similarity of the contributions of local density of\nstates coming from atoms with the same local environment is demonstrated. Local\ndensity of states of the atoms with unique local environments of an arbitrary\nselection of the structures is then used to train a machine learning model.\nThis model is used to predict the phonon spectra of twisted bilayer structures.\nPerformance of the trained model is discussed thoroughly via different\nselection of training and test sets, and it is shown that the model proves\neffective in predicting the vibrational properties of any given twisted bilayer\nstructure. The possible applications of the generic method presented which\nreaches far beyond twisted bilayer graphene is also discussed.",
        "positive": "Colossal pressure-induced softening in scandium fluoride: The counter-intuitive phenomenon of pressure-induced softening in materials\nis likely to be caused by the same dynamical behaviour that produces negative\nthermal expansion. Through a combination of molecular dynamics simulation on an\nidealised model and neutron diffraction at variable temperature and pressure,\nwe show the existence of extraordinary and unprecedented pressure-induced\nsoftening in the negative thermal expansion material scandium fluoride,\nScF$_3$, with values of the pressure-derivative of the bulk modulus $B$,\n$B^\\prime = \\partial B / \\partial P$, reaching as low as $-40 \\pm 1$."
    },
    {
        "anchor": "Efficiency of thin film photocells: We propose a new concept for the design of high-efficiency photocells based\non ultra-thin (submicron) semiconductor films of controlled thickness. Using a\nmicroscopic model of a thin dielectric layer interacting with incident\nelectromagnetic radiation we evaluate the efficiency of conversion of solar\nradiation into the electric power. We determine the optimal range of parameters\nwhich maximize the efficiency of such photovoltaic element.",
        "positive": "Large microwave generation from d.c. driven magnetic vortex oscillators\n  in magnetic tunnel junctions: Spin polarized current can excite the magnetization of a ferromagnet through\nthe transfer of spin angular momentum to the local spin system. This pure\nspin-related transport phenomena leads to alluring possibilities for the\nachievement of a nanometer scale, CMOS compatible and tunable microwave\ngenerator operating at low bias for future wireless communications. Microwave\nemission generated by the persitent motion of magnetic vortices induced by spin\ntransfer effect seems to be a unique manner to reach appropriate spectral\nlinewidth. However, in metallic systems, where such vortex oscillations have\nbeen observed, the resulting microwave power is much too small. Here we present\nexperimental evidences of spin-transfer induced core vortex precessions in\nMgO-based magnetic tunnel junctions with similar good spectral quality but an\nemitted power at least one order of magnitude stronger. More importantly,\nunlike to others spin transfer excitations, the thorough comparison between\nexperimental results and models provide a clear textbook illustration of the\nmechanisms of vortex precessions induced by spin transfer."
    },
    {
        "anchor": "Far infrared properties of the rare-earth scandate DyScO3: We present reflectance measurements in the infrared region on a single\ncrystal the rare earth scandate DyScO3. Measurements performed between room\ntemperature and 10 K allow to determine the frequency of the infrared-active\nphonons, never investigated experimentally, and to get information on their\ntemperature dependence. A comparison with the phonon peak frequency resulting\nfrom ab-initio computations is also provided. We finally report detailed data\non the frequency dependence of the complex refractive index of DyScO3 in the\nterahertz region, which is important in the analysis of terahertz measurements\non thin films deposited on DyScO3.",
        "positive": "Low energy spin wave excitations in bilayered magnetic manganite\n  La$_{2-2x}$Sr$_{1+2x}$Mn$_{2}$O$_{7}$ ($0.30\\leq{x}\\leq{0.50}$): We have studied the low-temperature behavior of the magnetization and the\nspecific heat of the bilayered perovskite system $%\nLa_{2-2x}Sr_{1+2x}Mn_{2}O_{7}$, for $0.30\\leq x\\leq 0.50$. Our analysis reveals\nthat below 30 K the temperature dependence of the magnetization of the\nferromagnetic samples, $x=0.30$, 0.32, and 0.36, in a field of 1T can be\ninterpreted in terms of the thermal excitations of a two-dimensional gas of\nferromagnetic magnons. The specific heat in zero field for these samples as for\nthe $x=0.50$ antiferromagnetic one, is linear with temperature between the\nrange of 1.8K $\\leq $ T $\\leq $ 10K. This behavior can be also explained by the\nmagnon gas model. By comparing specific heat measurements in zero field with\nthose taken in a field of 9T we are able to extract the lattice and electronic\ncontributions and determine the in-plane exchange interactions. That are found\nto be in reasonable agreement with the values inferred from the analysis of the\nmagnetization data and also with the values reported by inelastic neutron\nscattering studies. In addition, we found that the electronic density of states\nobtained for the $x=0.50$ sample is in agreement with previous band structure\ncalculations."
    },
    {
        "anchor": "First-principles study of multi-control graphene doping using\n  light-switching molecules: The high carrier mobility in graphene promises its utility in electronics\napplications. Azobenzene is a widely studied organic molecule for switchable\noptoelectronic devices that can be synthesized with a wide variety of ligands\nand deposited on graphene. Using first-principles calculations, we investigate\ngraphene doping by physisorbed azobenzene molecules with various\nelectron-donating and -accepting ligands. We confirm previous experimental\nresults that demonstrate greater p-doping of graphene for the trans compared to\ncis configuration when using a SO$_3$ electron-accepting ligand, however we\nfind that NO$_2$ ligands maximize the p-doping difference between isomers. We\nalso examine how these doping effects change when the graphene monolayer is\nsupported on a silica substrate. We then extend these findings by examining the\ndoping effects of an applied electrical bias and mechanical strain to the\ngraphene, which lead to changes in doping for both the trans and cis isomers.\nThese results demonstrate a new type of multi-control device combining light,\nelectric field, and strain to change carrier concentration in graphene.",
        "positive": "Disorder-Induced Weyl Semimetal Phase and Sequential Band Inversions in\n  PbSe-SnSe Alloys: The search for topological systems has recently broadened to include random\nsubstitutional alloys, which lack the specific crystalline symmetries that\nprotect topological phases, raising the question whether topological properties\ncan be preserved, or are modified by disorder. To address this question, we\navoid methods that assumed at the outset high (averaged) symmetry, using\ninstead a fully-atomistic, topological description of alloy. Application to\nPbSe-SnSe alloy reveals that topology survives in an interesting fashion: (a)\nspatial randomness removes the valley degeneracy (splitting larger than 150\nmeV), leading to a sequential inversion of the split valley components over a\nrange of compositions; (b) absence of inversion lifts spin degenerates, leading\nto a Weyl semimetal phase without the need of external magnetic field, an\nunexpected result, given that the alloy constituent compounds are\ninversion-symmetric. (a) and (b) underpin the topological physics at low\nsymmetry and complete the missing understanding of possible topological phases\nwithin the normal-topological insulator transition."
    },
    {
        "anchor": "Micro-alloying and the Toughness of Glasses: Modeling with Pinned\n  Particles: The usefulness of glasses, and particularly of metallic glasses, in\ntechnological applications is often limited by their toughness, which is\ndefined as the area under the stress vs. strain curve before plastic yielding.\nRecently toughness was found to increase significantly by the addition of small\nconcentrations of foreign atoms that act as pinning centers. We model this\nphenomenon at zero temperature and quasi-static straining with randomly\npositioned particles that participate in the elastic deformation but are pinned\nin the non-affine return to mechanical equilibrium. We find a very strong\neffect on toughness via the increase of both the shear modulus and the yield\nstress as a function of the density of pinned particles. Understanding the\nresults calls for analyzing separately the elastic, or \"Born term\" and the\ncontributions of the \"excess modes\" that result from glassy disorder. Finally\nwe present a scaling theory that collapses the data on one universal curve as a\nfunction of rescaled variables.",
        "positive": "Defect chemistry in layered transition-metal oxides from screened hybrid\n  density functional calculations: We report a comprehensive first-principles study of the thermodynamics and\ntransport of intrinsic point defects in layered oxide cathode materials\nLiMO$_2$ (M=Co, Ni), using density-functional theory and the\nHeyd-Scuseria-Ernzerhof screened hybrid functional. We find that LiCoO$_2$ has\na complex defect chemistry; different electronic and ionic defects can exist\nunder different synthesis conditions, and LiCoO$_2$ samples free of cobalt\nantisite defects can be made under Li-excess (Co-deficient) environments. A\ndefect model for lithium over-stoichiometric LiCoO$_2$ is also proposed, which\ninvolves negatively charged lithium antisites and positively charged small\n(hole) polarons. In LiNiO$_2$, a certain amount of Ni$^{3+}$ ions undergo\ncharge disproportionation and the concentration of nickel ions in the lithium\nlayers is high. Tuning the synthesis conditions may reduce the nickel antisites\nbut would not remove the charge disproportionation. In addition, we find that\nLiMO$_2$ cannot be doped $n$- or $p$-type; the electronic conduction occurs via\nhopping of small polarons and the ionic conduction occurs via migration of\nlithium vacancies, either through a monovacancy or divacancy mechanism,\ndepending on the vacancy concentration."
    },
    {
        "anchor": "The free path and the generation rate of a fast-moving electron\n  interacting with a dielectric media: In the framework of macroscopic continuous medium approach, we studied the\ninteraction between a fast-moving charged particle and dielectric or\nsemiconducting media with low energy electrically active excitations. The\nexcitations contribute to frequency dispersion of the media dielectric\npermittivity. Two types of processes induced by a moving charged particle are\nconsidered: electron-hole generation under interband transitions and excitation\nof polar optical phonons. For both processes we calculated and analyzed the\ntime- and space-dependent electric potential generated by the charged particle,\npolarization of the media, energy losses of the particle and other important\nconstituents of the interaction patterns. Obtained results can contribute to\ndeeper understanding of the charged particle beams interaction with a\nsemiconducting medium, as well as may be useful for versatile applications of\ncharged beams.",
        "positive": "Small dimensional microstrips embedded with ferromagnetic layers:\n  Numerical simulations and experimental results: We use a numerical electromagnetic simulation software to investigate a\nfiltering device consisting of a small dimensional microstrips embedded with a\nthin layer of ferromagnetic material and we compare our results to experimental\nresults. We are able to show good correlation of simulation versus experiment\nfor the magnitude of insertion loss and phase shift. The microstrips considered\nhave dimensions on the order of the skin depth of the conductor and hence the\nfield distribution is not easily calculated by analytic methods. We show that\nnumerical simulation methods provide an accurate means of characterizing these\nstructures."
    },
    {
        "anchor": "Detecting onset of chain scission and crosslinking of gamma-ray\n  irradiated elastomer surfaces using frictional force microscopy: We report here that atomic force microscope (AFM) in frictional force mode\ncan be used to detect onset of chain scission and crosslinking in polymeric and\nmacromolecular samples upon irradiation. A systematic investigation to detect\nchain scission and crosslinking of two elastomers: (1) Ethylene-propylene-diene\nmonomer rubber (EPDM) and (2) Fluorocarbon rubber (FKM) upon gamma-ray\nirradiation has been carried out using frictional force microscopy (FFM). From\nthe AFM results we observed that both the elastomers show a systematic\nsmoothening of its surfaces, as the gamma-ray dose rate increases. However, the\nfrictional property studied using FFM of the sample surfaces show an initial\nincrease and then a decrease as a function of dose rate. This behavior of\nincrease in its frictional property has been attributed to the onset of chain\nscission and the subsequent decrease in friction has been attributed to the\nonset of crosslinking of the polymer chains. The evaluated qualitative and\nsemi-quantitative changes observed in the overall frictional property as a\nfunction of gamma-ray dose rate for the two elastomers are presented in this\npaper.",
        "positive": "Bulk synthesis of Zn$_3$WN$_4$ via solid-state metathesis: Ternary nitrides are of growing technological importance, with applications\nas semiconductors, catalysts, and magnetic materials; however, new synthetic\ntools are needed to advance materials discovery efforts. Here, we show that\nZn$_3$WN$_4$ can be synthesized via metathesis reactions between Li$_6$WN$_4$\nand Zn$X_2$ ($X$ = Br, Cl, F). In situ synchrotron powder X-ray diffraction and\ndifferential scanning calorimetry show that the reaction onset is correlated\nwith the Zn$X_2$ melting point and that product purity is inversely correlated\nwith the reaction's exothermicity. High resolution synchrotron powder X-ray\ndiffraction measurements show that this bulk synthesis produces a structure\nwith substantial cation ordering, as opposed to the disordered structure\ninitially discovered via thin film sputtering. Diffuse reflectance spectroscopy\nreveals that Zn$_3$WN$_4$ powders exhibit two optical absorption onsets at 2.5\neV and 4.0 eV, indicating wide-bandgap semiconducting behavior and suggesting a\nsmall amount of structural disorder. We hypothesize that this synthesis\nstrategy is generalizable because many potential Li-$M$-N precursors (where $M$\nis a metal) are available for synthesizing new ternary nitride materials. This\nwork introduces a promising synthesis strategy that will accelerate the\ndiscovery of novel functional ternary nitrides and other currently inaccessible\nmaterials."
    },
    {
        "anchor": "Enhancement of anomalous Nernst effect in Ni/Pt superlattice: We report an enhancement of the anomalous Nernst effect (ANE) in Ni/Pt (001)\nepitaxial superlattices. The transport and magneto-thermoelectric properties\nwere investigated for the Ni/Pt superlattices with various Ni layer thicknesses\n(${\\it t}$). The anomalous Nernst coefficient was increased up to more than 1\n${\\mu}$V K$^{-1}$ for 2.0 nm ${\\leq}$ ${\\it t}$ ${\\leq}$ 4.0 nm, which was the\nremarkable enhancement compared to the bulk Ni. It has been found that the\nlarge transverse Peltier coefficient (${\\alpha}$$_{xy}$), reaching\n${\\alpha}$$_{xy}$ = 4.8 A K$^{-1}$ m$^{-1}$ for ${\\it t}$ = 4.0 nm, plays a\nprime role for the enhanced ANE of the Ni/Pt (001) superlattices.",
        "positive": "Grain Boundary Motion on Curved Substrate: Grain boundary (GB) kinetics is important for many applications in 2d\nmaterials and metal thin films. To study how the substrate shape affects GB\nmobility and kinetics, we develop a kinetic Monte Carlo (kMC) simulation method\nand an analytical model for GBs on the curved substrate by combining\ndisconnection theory and by Foppl von Karman equations. Using sinusoidal MoS2\nas an example, we can increase its GB mobility more than 50 times by changing\nsubstrate shape amplitudes and periods. We find that amplitude change GB\nmobility exponentially while wave vector change GB mobility linearly. The\nsinusoidal GB kinetic shape has wave vector twice as substrate and amplitude\nproportional to substrate squared amplitude."
    },
    {
        "anchor": "Onsager approach to 1D solidification problem and its relation to phase\n  field description: We give a general phenomenological description of the steady state 1D front\npropagation problem in two cases: the solidification of a pure material and the\nisothermal solidification of two component dilute alloys.\n  The solidification of a pure material is controlled by the heat transport in\nthe bulk and the interface kinetics.\n  The isothermal solidification of two component alloys is controlled by the\ndiffusion in the bulk and the interface kinetics.\n  We find that the condition of positive-definiteness of the symmetric Onsager\nmatrix of interface kinetic coefficients still allows an arbitrary sign of the\nslope of the velocity-concentration line near the solidus in the alloy problem\nor of the velocity-temperature line in the case of solidification of a pure\nmaterial. This result offers a very simple and elegant way to describe the\ninteresting phenomenon of a possible non-single-value behavior of velocity\nversus concentration which has previously been discussed by different\napproaches. We also discuss the relation of this Onsager approach to the thin\ninterface limit of the phase field description.",
        "positive": "A Comparative Study on Spin-Orbit Torque Efficiencies from\n  W/ferromagnetic and W/ferrimagnetic Heterostructures: It has been shown that W in its resistive form possesses the largest\nspin-Hall ratio among all heavy transition metals, which makes it a good\ncandidate for generating efficient dampinglike spin-orbit torque (DL-SOT)\nacting upon adjacent ferromagnetic or ferrimagnetic (FM) layer. Here we provide\na systematic study on the spin transport properties of W/FM magnetic\nheterostructures with the FM layer being ferromagnetic\nCo$_{20}$Fe$_{60}$B$_{20}$ or ferrimagnetic Co$_{63}$Tb$_{37}$ with\nperpendicular magnetic anisotropy. The DL-SOT efficiency $|\\xi_{DL}|$, which is\ncharacterized by a current-induced hysteresis loop shift method, is found to be\ncorrelated to the microstructure of W buffer layer in both\nW/Co$_{20}$Fe$_{60}$B$_{20}$ and W/Co$_{63}$Tb$_{37}$ systems. Maximum values\nof $|\\xi_{DL}|\\approx 0.144$ and $|\\xi_{DL}|\\approx 0.116$ are achieved when\nthe W layer is partially amorphous in the W/Co$_{20}$Fe$_{60}$B$_{20}$ and\nW/Co$_{63}$Tb$_{37}$ heterostructures, respectively. Our results suggest that\nthe spin Hall effect from resistive phase of W can be utilized to effectively\ncontrol both ferromagnetic and ferrimagnetic layers through a DL-SOT mechanism."
    },
    {
        "anchor": "Phenomenological description of bright domain walls in\n  ferroelectric-antiferroelectric layered chalcogenides: Recently, a layered ferroelectric CuInP2Se6 was shown to exhibit domain walls\nwith locally enhanced piezoresponse - a striking departure from the\nobservations of nominally zero piezoresponse in most ferroelectrics. Although\nit was proposed that such \"bright\" domain walls are phase-boundaries between\nferri- and antiferroelectrically ordered regions of the materials, the physical\nmechanisms behind the existence and response of these boundaries remain to be\nunderstood. Here, using Landau-Ginzburg-Devonshire phenomenology combined with\nfour sub-lattices model, we describe quantitatively the bright-contrast and\ndark-contrast domain boundaries between the antiferroelectric, ferroelectric or\nferrielectric long-range ordered phases in a layered\nferroelectric-antiferroelectric ferroics, such as CuInP2(S1-ySey)6",
        "positive": "Universality of Dzyaloshinskii-Moriya interaction effect over\n  domain-wall creep and flow regimes: Chirality causes diverse phenomena in nature such as the formation of\nbiological molecules, antimatters, non-collinear spin structures, and magnetic\nskyrmions. The chirality in magnetic materials is often caused by the\nnoncollinear exchange interaction, called the Dzyaloshinskii-Moriya interaction\n(DMI). The DMI produces topological spin alignments such as the magnetic\nskyrmions and chiral domain walls (DWs). In the chiral DWs, the DMI generates\nan effective magnetic field $H_{DMI}$, resulting in a peculiar DW speed\nvariation in the DW creep regime. However, the role of $H_{DMI}$ over the\ndifferent DW-dynamics regimes remains elusive, particularly due to recent\nobservation of distinct behaviors between the creep and flow regimes. We hereby\ndemonstrate experimentally that the role of $H_{DMI}$ is invariant over the\ncreep and flow regimes. In the experiments, the pure DMI effect is quantified\nby decomposing the symmetric and antisymmetric contributions of the DW motion.\nThe results manifest that the antisymmetric contribution vanishes gradually\nacross the creep and flow regimes, revealing that the symmetric contribution\nfrom $H_{DMI}$ is unchanged. Though the DW dynamics is governed by distinct\nmechanisms, the present observation demonstrates the uniqueness of the DMI\neffect on the DWs over the creep and flow regimes."
    },
    {
        "anchor": "Enhanced Kerr effect in vertically aligned deformed helix ferroelectric\n  liquid crystals: We disclose the vertically aligned deformed helix ferroelectric liquid\ncrystal (VADHFLC) whose Kerr constant ($K_{\\mathrm{kerr}}\\approx 130$~nm/V$^2$\nat $\\lambda=543$~nm) is one order of magnitude higher than any other value\npreviously reported for liquid crystalline structures. Under certain\nconditions, the phase modulation with ellipticity less than 0.05 over the range\nof continuous and hysteresis free electric adjustment of the phase shift from\nzero to 2$\\pi$ have been obtained at sub-kilohertz frequency.",
        "positive": "Magnetically collected platinum/nickel alloy nanoparticles -- insight\n  into low noble metal content catalysts for hydrogen evolution reaction: The hydrogen evolution reaction (HER) is a key process in electrochemical\nwater splitting. To lower the cost and environmental impact of this process, it\nis highly motivated to develop electrocatalysts with low or no content of noble\nmetals. Here we report on a novel and ingenious synthesis of hybrid PtxNi1-x\nelectrocatalysts in the form of a nanoparticle-necklace structure named\nnanotrusses, with very low noble metal content. The nanotruss structure\npossesses important features, such as good conductivity, high surface area,\nstrong interlinking and substrate adhesion, which renders for an excellent HER\nactivity. Specifically, the best performing Pt0.05Ni0.95 sample, demonstrates a\nTafel slope of 30 mV dec-1 in 0.5 M H2SO4, and an overpotential of 20 mV at a\ncurrent density of 10 mA cm-2 with high stability. The impressive catalytic\nperformance is further rationalized in a theoretical study, which provides\ninsight into the mechanism for how such small platinum content can allow for\nclose-to-optimal adsorption energies for hydrogen."
    },
    {
        "anchor": "Composite excitonic states in doped semiconductors: We present a theoretical model of composite excitonic states in doped\nsemiconductors. Many-body interactions between a photoexcited electron-hole\npair and the electron gas are integrated into a computationally tractable\nfew-body problem, solved by the variational method. We focus on electron-doped\nML-MoSe$_2$ and ML-WSe$_2$ due to the contrasting character of their conduction\nbands. In both cases, the core of the composite is a tightly-bound trion (two\nelectrons and valence-band hole), surrounded by a region depleted of electrons.\nThe composite in ML-WSe$_2$ further includes a satellite electron with\ndifferent quantum numbers. The theory is general and can be applied to\nsemiconductors with various energy-band properties, allowing one to calculate\ntheir excitonic states and to quantify the interaction with the Fermi sea.",
        "positive": "Enhanced magnetocaloric effect from Cr substitution in Ising lanthanide\n  gallium garnets $Ln_3\\text{CrGa}_4\\text{O}_{12}$ ($Ln$ = Tb, Dy, Ho): A detailed study on the crystal structure and bulk magnetic properties of Cr\nsubstituted Ising type lanthanide gallium garnets\n$Ln_3\\text{CrGa}_4\\text{O}_{12}$ ($Ln$ = Tb, Dy, Ho) has been carried out using\nroom temperature powder X-Ray and neutron diffraction, magnetic susceptibility,\nisothermal magnetisation and heat capacity measurements. The magnetocaloric\neffect (MCE) in $Ln_3\\text{CrGa}_4\\text{O}_{12}$ is compared to that of\n$Ln_3\\text{Ga}_5\\text{O}_{12}$. In lower magnetic fields attainable by a\npermanent magnet ($\\leq$ 2 T), Cr substitution greatly enhances the MCE by 20%\nfor $Ln$ = Dy and 120% for $Ln$ = Ho compared to the unsubstituted\n$Ln_3\\text{Ga}_5\\text{O}_{12}$. This is likely due to changes in the magnetic\nground state as Cr substitution also significantly reduces the frustration in\nthe magnetic lattice for the Ising type $Ln_3\\text{Ga}_5\\text{O}_{12}$."
    },
    {
        "anchor": "Electronic and Geometrical Structure of Potassium doped Phenanthrene: The geometrical and electronic structure of potassium doped phenanthrene,\n\\ce{K3C14H10}, have been studied by first-principles density functional theory.\nThe main effect of potassium doping is to inject charge in the narrow\nphenanthrene conduction band, rendering the system metallic. The Fermi surface\nfor the experimental X-rays structure is composed of two sheets with marked one\nand two dimensional character respectively.",
        "positive": "The mechanism of ion induced amorphization in Si: Some results on damage build up in, and amorphization of, Si, induced by\n25-30 keV Al$_5^-$, Si$_5^-$ and Cs$^-$ ions, at room temperature, are\nreported. We show that at low energy, amorphization is a nucleation and growth\nprocess, based on the direct impact mechanism. With an Avrami exponent $\\sim\n1.6$, the growth towards amorphization seems to be diffusion limited. A\ntransition to a completely amorphized state is indicated at a dose exceeding 17\neV/atom, which is higher than 6-12 eV/atom as predicted by simulations. The\nobserved higher threshold could be due to temperature effects although an\nunderestimation of keV-energy recoils, in simulation, may not be ruled out."
    },
    {
        "anchor": "Kinetically determined shapes of grain boundaries in CVD graphene: Predicting the shape of grain boundaries is essential to control results of\nthe growth of large graphene crystals. A global energy minimum search\npredicting the most stable final structure contradicts experimental\nobservations. Here we present Monte Carlo simulation of kinetic formation of\ngrain boundaries (GB) in graphene during collision of two growing graphene\nflakes. Analysis of the resulting GBs for the full range of misorientation\nangles $\\alpha$ allowed us to identify a hidden (from post facto analysis such\nas microscopy) degree of freedom - the edge misorientation angle $\\beta$. Edge\nmisorientation characterizes initial structure rather than final structure and\ntherefore provides more information about growth conditions. Use of $\\beta$\nenabled us to explain disagreements between the experimental observations and\ntheoretical work. Finally, we report an analysis of an interesting special case\nof zero-tilt GBs for which structure is determined by two variables describing\nthe relative shift of initial islands. We thereby present analysis of the full\nrange of tilt GB ( $\\beta\\neq$ 0) and translational GB ( $\\beta$ = 0). Based on\nour findings we propose strategies of controlling the GB morphology in\nexperiments, which paves the way to a better control over graphene structure\nand properties for advanced applications.",
        "positive": "Complete miscibility amongst AV$_3$Sb$_5$ kagome superconductors: design\n  of mixed A-site AV$_3$Sb$_5$ (A: K, Rb, Cs) alloys: In this work we explore the chemical-property phase diagram of the\nAV$_3$Sb$_5$ family through A-site alloying. We demonstrate full miscibility of\nthe alkali-site, highlighting that the three parent compounds are the terminal\nends of a single solid-solution. Using both polycrystalline and single crystal\nmethods, we map the dependence of the two primary electronic instabilities: (1)\nthe onset of charge density wave (CDW) order ($T_\\text{CDW}$) and (2) the onset\nof superconductivity ($T_\\text{c}$) with alkali-site composition. We show\ncontinuous trends in both $T_\\text{CDW}$ and $T_\\text{c}$, including a region\nof enhanced CDW stability in K$_{1-x}$Cs$_{x}$V$_3$Sb$_5$ alloys. Together, our\nresults open new routes for chemical perturbation and exploration of the\nchemical-property relationships in the class of AV$_3$Sb$_5$ kagome\nsuperconductors."
    },
    {
        "anchor": "Recursion and Path-Integral Approaches to the Analytic Study of the\n  Electronic Properties of $C_{60}$: The recursion and path-integral methods are applied to analytically study the\nelectronic structure of a neutral $C_{60}$ molecule. We employ a tight-binding\nHamiltonian which considers both the $s$ and $p$ valence electrons of carbon.\nFrom the recursion method, we obtain closed-form {\\it analytic} expressions for\nthe $\\pi$ and $\\sigma$ eigenvalues and eigenfunctions, including the highest\noccupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital\n(LUMO) states, and the Green's functions. We also present the local densities\nof states around several ring clusters, which can be probed experimentally by\nusing, for instance, a scanning tunneling microscope. {}From a path-integral\nmethod, identical results for the energy spectrum are also derived. In\naddition, the local density of states on one carbon atom is obtained; from this\nwe can derive the degree of degeneracy of the energy levels.",
        "positive": "Atomic cluster expansion force field based thermal property material\n  design with density functional theory level accuracy in non-equilibrium\n  molecular dynamics calculations over sub-million atoms: Non-equilibrium molecular dynamics (NEMD) techniques are widely used for\ninvestigating lattice thermal conductivity. Recently, machine learning force\nfields (MLFFs) have emerged as a promising approach to enhance the precision in\nNEMD simulations. This study is aimed at demonstrating the potential of MLFFs\nin realizing NEMD calculations for large-scale systems containing over 100,000\natoms with density functional theory (DFT)-level accuracy. Specifically, the\natomic cluster expansion (ACE) force field is employed, using Si as an example.\nThe ACE potential incorporates 4-body interactions and features a training\ndataset consisting of 1000 order structures from first-principles molecular\ndynamics calculations, resulting in a highly accurate vibrational spectrum.\nMoreover, the ACE potential can reproduce thermal conductivity values\ncomparable with those derived from DFT calculations via the Boltzmann equation.\nTo demonstrate the application of MLFFs to systems containing over 100,000\natoms, NEMD simulations are conducted on thin films ranging from 100 nm to 500\nnm, with the 100 nm films exhibiting defect rates of up to 1.5%. The results\nshow that the thermal conductivity deviates by less than 5% from DFT or\ntheoretical results in both scenarios, which highlights the ability of the ACE\npotential in calculating the thermal conductivity on a large scale with\nDFT-level accuracy. The proposed approach is expected to promote the\napplication of MLFFs in various fields and serve as a feasible alternative to\nvirtual experiments. Furthermore, this work demonstrates the potential of MLFFs\nin enhancing the accuracy of NEMD simulations for investigating lattice thermal\nconductivity for systems with over 100,000 atoms."
    },
    {
        "anchor": "Room-temperature ferromagnetism in the mixtures of the TiO2 and Co3O4\n  powders: We report here the observation of ferromagnetism (FM) at 300 K in mixtures of\nTiO2 and Co3O4 powders despite the antiferromagnetic and diamagnetic character\nof both oxides respectively. The ferromagnetic behavior is found in the early\nstages of reaction and only for TiO2 in anatase structure; no FM is found for\nidentical samples prepared with rutile-TiO2. Optical spectroscopy and X-ray\nabsorption spectra confirm a surface reduction of octahedral Co+3->Co+2 in the\nmixtures which is in the origin of the observed magnetism",
        "positive": "Graph Neural Network for Predicting the Effective Properties of\n  Polycrystalline Materials: A Comprehensive Analysis: We develop a polycrystal graph neural network (PGNN) model for predicting the\neffective properties of polycrystalline materials, using the Li7La3Zr2O12\nceramic as an example. A large-scale dataset with >5000 different\nthree-dimensional polycrystalline microstructures of finite-width grain\nboundary is generated by Voronoi tessellation and processing of the electron\nbackscatter diffraction images. The effective ion conductivities and elastic\nstiffness coefficients of these microstructures are calculated by\nhigh-throughput physics-based simulations. The optimized PGNN model achieves a\nlow error of <1.4% in predicting all three diagonal components of the effective\nLi-ion conductivity matrix, outperforming a linear regression model and two\nbaseline convolutional neural network models. Sequential forward selection\nmethod is used to quantify the relative importance of selecting individual\ngrain (boundary) features to improving the property prediction accuracy,\nthrough which both the critical and unwanted node (edge) feature can be\ndetermined. The extrapolation performance of the trained PGNN model is also\ninvestigated. The transfer learning performance is evaluated by using the PGNN\nmodel pretrained for predicting conductivities to predict the elastic\nproperties of the same set of microstructures."
    },
    {
        "anchor": "Layered 2D crystals by design: optimisation of Sb$_2$Te$_3$-GeTe van der\n  Waals superlattices: Herein a genetic algorithm for optimising the design of layered 2D\nheterostructure is proposed. As a proof-of-concept it is applied to\nSb$_2$Te$_3$-GeTe phase-change material superlattices, and the resulting lowest\nenergy structure is grown experimentally. The similarity of the computational\nand experimental structures is verified with the comparison of XRD spectra. The\nstructure is found to be within 0.92 meV/at. from the energetically most\nfavorable known structure for Ge$_2$Sb$_2$Te$_5$.",
        "positive": "Polar charge induced self-assembly: An electric effect that causes\n  non-isotropic nanorod growth in wurtzite semiconductors: Crystals grow by gathering and bonding of atoms to form an ordered structure.\nTypically, the growth is equally probable in all crystalline directions, but\nsometimes, it is not, as is the case of nanowire growth. Nanowire growth is\nexplained, in most cases, by the presence of liquid metal droplets that mediate\nbetween an incoming flux of atoms and a substrate or an existing crystal\nnucleus, while defining the lateral dimension. Here, we report and explain a\npreviously unknown mode of non-isotropic crystal growth observed in two\nwurtzite semiconductors, InN and ZnO. Being of polar structure, wurtzite\ncrystals possess a built-in internal electric field. Thermally-excitied charges\nscreen the built-in electric field during growth in a non-uniform, yet\nsymmetric, manner, causing the formation of symmetric domains of inverted\npolarity. These domains limit the lateral expansion of the crystal, inducing a\nfiber growth mode. The mechanism described here elucidates previously\nunexplained phenomena in the growth of group III-nitrides on sapphire,\nemphasizing the need to consider the effects of built-in electric fields in the\ngrowth of polar semiconductors."
    },
    {
        "anchor": "Structural and Magnetic Characterization of CuxMn1-xFe2O4 (x= 0.0, 0.25)\n  Ferrites Using Neutron Diffraction and Other Techniques: Manganese ferrite (MnFe2O4) and copper doped manganese ferrite\n(Mn0.75Cu0.25Fe2O4) soft materials were synthesized through solid-state\nsintering method. The phase purity and quality were confirmed from x-ray\ndiffraction patterns. Then the samples were subjected to neutron diffraction\nexperiment and the diffraction data were analyzed using FullProf software\npackage. The surface morphology of the soft material samples was studied using\na scanning electron microscope (SEM). Crystal parameters, crystallite\nparameters, occupancy at A and B sites of the spinel structure, magnetic\nmoments of the atoms at various locations, symmetries, oxygen position\nparameters, bond lengths etc. were measured and compared with the reference\ndata. In MnFe2O4, both octahedral (A) and tetrahedral (B) positions are shared\nby Mn2+ and Fe2+/3+ cations, here A site is predominantly occupied by Fe2+ and\nB site is occupied by Mn at 0.825 occupancy. The Cu2+ ions in Cu0.25Mn0.75Fe2O4\nmostly occupy the B site. Copper mostly occupy the Octahedral (16d) sites. The\nlength of the cubic lattice decreases with the increasing Copper content. The\nmagnetic properties, i.e. A or B site magnetic moments, net magnetic moment\netc. were measured using neutron diffraction analysis and compared with the\nbulk magnetic properties measured with VSM studies.",
        "positive": "Materials Cartography: Representing and Mining Material Space Using\n  Structural and Electronic Fingerprints: As the proliferation of high-throughput approaches in materials science is\nincreasing the wealth of data in the field, the gap between\naccumulated-information and derived-knowledge widens. We address the issue of\nscientific discovery in materials databases by introducing novel analytical\napproaches based on structural and electronic materials fingerprints. The\nframework is employed to (i) query large databases of materials using\nsimilarity concepts, (ii) map the connectivity of the materials space (i.e., as\na materials cartogram) for rapidly identifying regions with unique\norganizations/properties, and (iii) develop predictive Quantitative Materials\nStructure-Property Relation- ships (QMSPR) models for guiding materials design.\nIn this study, we test these fingerprints by seeking target material\nproperties. As a quantitative example, we model the critical temperatures of\nknown superconductors. Our novel materials fingerprinting and materials\ncartography approaches contribute to the emerging field of materials\ninformatics by enabling effective computational tools to analyze, visualize,\nmodel, and design new materials."
    },
    {
        "anchor": "Van der Waals solid phase epitaxy to grow large-area manganese-doped\n  MoSe$_2$ few-layers on SiO$_2$/Si: Large-area growth of continuous transition metal dichalcogenides (TMDCs)\nlayers is a prerequisite to transfer their exceptional electronic and optical\nproperties into practical devices. It still represents an open issue nowadays.\nElectric and magnetic doping of TMDC layers to develop basic devices such as\np-n junctions or diluted magnetic semiconductors for spintronic applications\nare also an important field of investigation. Here, we have developed two\ndifferent techniques to grow MoSe$_2$ mono- and multi-layers on SiO$_2$/Si\nsubstrates over large areas. First, we co-deposited Mo and Se atoms on\nSiO$_2$/Si by molecular beam epitaxy in the van der Waals regime to obtain\ncontinuous MoSe$_2$ monolayers over 1 cm$^2$. To grow MoSe$_2$ multilayers, we\nthen used the van der Waals solid phase epitaxy which consists in depositing an\namorphous Se/Mo bilayer on top of a co-deposited MoSe$_2$ monolayer which\nserves as a van der Waals growth template. By annealing, we obtained continuous\nMoSe$_2$ multilayers over 1 cm$^2$. Moreover, by inserting a thin layer of Mn\nin the stack, we could demonstrate the incorporation of up to 10 \\% of Mn in\nMoSe$_2$ bilayers.",
        "positive": "Topological effects of phonons in GaN and AlxGa1-xN: A potential\n  perspective for tuning phonon transport: Tuning thermal transport in semiconductor nanostructures is of great\nsignificance for thermal management in information and power electronics. With\nexcellent transport properties, such as ballistic transport, immunity to point\ndefects and disorders, and forbidden backscattering, topological phonon surface\nstates show remarkable potential in addressing this issue. Herein, topological\nphonon analyses are performed on hexagonal wurtzite GaN to check the\ntopological characteristics of phonons. And other nitrides of the same family,\ni.e., AlN and AlGaN alloy, are also calculated from a topological phonon phase\ntransition perspective. With the aid of first-principle calculations and\ntopological phonon theory, Weyl phonon states, which host surfaces states\nwithout backscattering, are investigated for all these materials. The results\nshow that there is no nontrivial topological phonon state in GaN. However, by\nintroducing Al atoms, i.e., in wurtzite type AlN and AlGaN, more than one Weyl\nphonon point is found, confirmed by obvious topological characteristics,\nincluding non-zero integer topological charges, source/sink in Berry curvature\ndistributions, surface local density of states and surface arcs. As AlN and\nAlGaN are typical materials in AlGaN/GaN heterostructure based electronics, the\nexistence of topological phonon states in them will benefit thermal management\nby facilitating the design of one-way interfacial phonon transport without\nbackscattering."
    },
    {
        "anchor": "Efficient determination of the Hamiltonian and electronic properties\n  using graph neural network with complete local coordinates: Despite the successes of machine learning methods in physical sciences,\nprediction of the Hamiltonian, and thus electronic properties, is still\nunsatisfactory. Here, based on graph neural network architecture, we present an\nextendable neural network model to determine the Hamiltonian from ab initio\ndata, with only local atomic structures as inputs. Rotational equivariance of\nthe Hamiltonian is achieved by our complete local coordinates. The local\ncoordinates information, encoded using the convolutional neural network and\ndesigned to preserve Hermitian symmetry, is used to map hopping parameters onto\nlocal structures. We demonstrate the performance of our model using graphene\nand SiGe random alloys as examples. We show that our neural network model,\nalthough trained using small-size systems, can predict the Hamiltonian, as well\nas electronic properties such as band structures and densities of states (DOS)\nfor large-size systems within the ab initio accuracy, justifying its\nextensibility. In combination with the high efficiency of our model, which\ntakes only seconds to get the Hamiltonian of a 1728-atom system, present work\nprovides a general framework to predict electronic properties efficiently and\naccurately, which provides new insights into computational physics and will\naccelerate the research for large-scale materials.",
        "positive": "Graphite and graphene as perfect spin filters: Based upon the observations (i) that their in-plane lattice constants match\nalmost perfectly and (ii) that their electronic structures overlap in\nreciprocal space for one spin direction only, we predict perfect spin filtering\nfor interfaces between graphite and (111) fcc or (0001) hcp Ni or Co. The spin\nfiltering is quite insensitive to roughness and disorder. The formation of a\nchemical bond between graphite and the open $d$-shell transition metals that\nmight complicate or even prevent spin injection into a single graphene sheet\ncan be simply prevented by dusting Ni or Co with one or a few monolayers of Cu\nwhile still preserving the ideal spin injection property."
    },
    {
        "anchor": "A unified theory of grain growth in polycrystalline materials: Grain growth is a ubiquitous and fundamental phenomenon observed in the\ncellular structures with the grain assembly separated by a network of grain\nboundaries, including metals and ceramics. However, the underlying mechanism of\ngrain growth has remained ambiguous for more than 60 years. The models for\ngrain growth, based on the classically linear relationship between the grain\nboundary migration and capillary driving force, generally predict normal grain\ngrowth. Quantitative model for abnormal grain growth is lacking despite decades\nof efforts. Here, we present a unified model to reveal quantitatively how grain\ngrowth evolves, which predicts the normal, abnormal and stagnant behaviors of\ngrain growth in polycrystalline materials. Our model indicates that the\nrelationship between grain boundary migration and capillary driving force is\ngenerally nonlinear, but will switch to be the classically linear relationship\nin a specific case. Furthermore, the grain growth experiments observed in\npolycrystalline SrTiO3 demonstrates the validity of the unified model. Our\nstudy provides a unified, quantitative model to understand and predict grain\ngrowth in polycrystalline materials, and thus offers helpful guides for the\nmicrostructural design to optimize the properties of polycrystalline materials.",
        "positive": "Double band inversion in the topological phase transition of Ge1-xSnx\n  alloys: We use first-principles simulation and virtual crystal approximation to\nreveal the unique double band inversion and topological phase transition in\nGe1-xSnx alloys. Wavefunction parity, spatial charge distribution and surface\nstate spectrum analyses suggest that the band inversion in Ge1-xSnx is relayed\nby its first valence band. As the system evolves from Ge to {\\alpha}-Sn, its\nconduction band moves down, and inverts with the first and the second valence\nbands consecutively. The first band inversion makes the system nontrivial,\nwhile the second one does not change the topological invariant of the system.\nBoth the band inversions yield surface modes spanning the individual inverted\ngaps, but only the surface mode in the upper gap associates with the nontrivial\nnature of tensile-strained {\\alpha}-Sn."
    },
    {
        "anchor": "Simulation of metal-oxide melt interaction in view of kinetics of\n  chemical reactions in the interphase boundary: Thermodynamics analysis of oxidation-reduction reactions between metal melt\nand slag (1) provides answers to certain practical issues such as the path of\nspecific chemical reactions, final (equilibrium) phase composition, and the\nelements that are reduced and oxidized at given physical parameters. Although\nconsiderable, this is obviously not enough to analyze real technological\nsystems, because the required equilibrium cannot be normally achieved despite\nhigh temperatures of welding and metallurgical processes. Hence, a dynamic\nproblem has to be resolved here, which is calculating phase composition as a\nfunction of time. This cannot be achieved without knowing the rates of element\nconcentration changes in each and every phase, and also technological\nparameters of the process. Relevant studies are detailed in(2-19). This paper\nanalyzes special kinetic features of physical and chemical processes in the\nmetal and oxide melt interface.",
        "positive": "Surface spin dynamics of antiferromagnetically coupled frustrated\n  triangular films: Results are presented for spin-wave dispersions in geometrically frustrated\nstacked triangular antiferromagnets with a thin film or semi-infinite geometry\nhaving either zero, easy-plane, or easy-axis anisotropy. Surface effects on the\nequilibrium spin configurations and excitation spectrum are investigated for\nthe case of antiferromagnetically coupled films, serving to extend previous\nresults on ferromagnetically coupled layers [E. Meloche et al., Phys. Rev. B\n74, 094424 (2006)]. An operator equation of motion formalism is applied to\nsystems which are quasi-one and quasi-two dimensional in character. In contrast\nto the case of ferromagnetically coupled films the new results show surface\nmodes that are well separated in frequency from bulk excitations. Magnetic\nexcitations in thin films with an even or an odd number of layers show\nqualitatively different behavior. These results are relevant for a wide variety\nof stacked triangular antiferromagnetics materials."
    },
    {
        "anchor": "Dynamics of Successive Minor Hysteresis Loops: Cumulative growth of successive minor hysteresis loops in Co/Pd multilayers\nwith perpendicular anisotropy was studied in the context of time dependent\nmagnetization reversal dynamics. We show that in disordered ferromagnets, where\nmagnetization reversal involves nucleation, domains' expansion and\nannihilation, differences between the time dependencies of these processes are\nresponsible for accumulation of nuclei for rapid domain expansion, for the\nasymmetry of forward and backward magnetization reversals and for the\nrespective cumulative growth of hysteresis loops. Loops stop changing and\nbecome macroscopically reproducible when populations of upward and downward\nnucleation domains balance each other and the respective upward and downward\nreversal times stabilize.",
        "positive": "Effect of alloying on the microstructure, phase stability, hardness and\n  partitioning behavior of a new dual-superlattice nickel-based superalloy: A novel y-y'-y\" dual-superlattice superalloy, with promising mechanical\nproperties up to elevated temperatures was recently reported. The present work\nemploys state of the art chemical and spatial characterization techniques to\nstudy the effect systematic additions of Mo, W and Fe and variations in Nb and\nAl contents have on the phase fraction, thermal stability, elemental\npartitioning and mechanical properties. Alloys were produced through arc\nmelting followed by heat treatment. Multi-scale characterization techniques and\nhardness testing were employed to characterize their microstructure, thermal\nstability and mechanical properties. Alterations in such properties or in\nelemental partitioning behaviour were then explained through thermodynamic\nmodelling.\n  A modest addition of 1.8 at.% Mo had a strong effect on the microstructure\nand thermal stability: it minimized microstructural coarsening during heat\ntreatments while not significantly decreasing the y' solvus temperature. A\nreduction of Nb by 0.6 at.%, strongly reduced the y\" volume fraction, without\naffecting the y' volume fraction. The reduced precipitate fraction led to a\nsignificant reduction in alloy hardness. Fe, added to achieve better\nprocessability and reduced material cost, decreased the y' solvus temperature\nand caused rapid microstructural coarsening during heat treatments, without\naffecting alloy hardness. A reduction of Al by 0.4 at.%, reduced the y' volume\nfraction and the y' solvus temperature, also without affecting alloy hardness.\nThe addition of 0.9 at.% W decreased the y' solvus temperature but increased\nboth precipitate volume fractions. These data will be invaluable to optimize\ncurrent alloy design and to inform future alloy design efforts."
    },
    {
        "anchor": "Magnon straintronics in the 2D van der Waals ferromagnet CrSBr from\n  first-principles: The recent isolation of two-dimensional (2D) magnets offers tantalizing\nopportunities for spintronics and magnonics at the limit of miniaturization.\nOne of the key advantages of atomically-thin materials is their outstanding\ndeformation capacity, which provides an exciting avenue to control their\nproperties by strain engineering. Herein, we investigate the magnetic\nproperties, magnon dispersion and spin dynamics of the air-stable 2D magnetic\nsemiconductor CrSBr ($T_C$ = 146 K) under mechanical strain using\nfirst-principles calculations. Our results provide a deep microscopic analysis\nof the competing interactions that stabilize the long-range ferromagnetic order\nin the monolayer. We showcase that the magnon dynamics of CrSBr can be modified\nselectively along the two main crystallographic directions as a function of\napplied strain, probing the potential of this quasi-1D electronic system for\nmagnon straintronics applications. Moreover, we predict a strain-driven\nenhancement of $T_C$ considering environmental screening by ~30%, allowing the\npropagation of spin waves at higher temperatures.",
        "positive": "Engineered spin-valve type magnetoresistance in\n  Fe$_3$O$_4$-CoFe$_2$O$_4$ core-shell nanoparticles: Naturally occurring spin-valve-type magnetoresistance (SVMR), recently\nobserved in Sr2FeMoO6 samples, suggests the possibility of decoupling the\nmaximal resistance from the coercivity of the sample. Here we present the\nevidence that SVMR can be engineered in specifically designed and fabricated\ncore-shell nanoparticle systems, realized here in terms of soft magnetic Fe3O4\nas the core and hard magnetic insulator CoFe2O4 as the shell materials. We show\nthat this provides a magnetically switchable tunnel barrier that controls the\nmagnetoresistance of the system, instead of the magnetic properties of the\nmagnetic grain material, Fe3O4, and thus establishing the feasibility of\nengineered SVMR structures."
    },
    {
        "anchor": "Unconventional iron-magnesium compounds at terapascal pressures: Being a lithophile element at ambient pressure, magnesium is long believed to\nbe immiscible with iron. A recent study by Gao et al. [1] showed that pressure\nturns magnesium into a siderophile element and can produce unconventional Fe-Mg\ncompounds. Here, we extend the investigation to exoplanetary pressure\nconditions using an adaptive genetic algorithm-based variable-composition\nstructural prediction approach. We identify several Fe-Mg phases up to 3 TPa.\nOur cluster alignment analysis reveals that most of the predicted Fe-Mg\ncompounds prefer a BCC packing motif at terapascal pressures. This study\nprovides a more comprehensive structure database to support future\ninvestigations of the high-pressure structural behavior of Fe-Mg and ternary,\nquaternary, etc. compounds involving these elements.",
        "positive": "Referenes for tensile strength of vitreous silica at room temperature: Some references for the breaking strength of fused silica fibers compiled in\n1999."
    },
    {
        "anchor": "Dislocation Based Mechanics: the various contributions of Dislocation\n  Dynamics simulations: Plastic deformation In crystalline materials is controlled by the motion and\ninteractions of dislocations [AND 17]. Discrete Dislocation Dynamics (DDD)\nsimulations have now existed for about 25 years to investigate plastic flow at\nthe mesoscale, which lies at a critical position between two very different\nscales. At small scale, atomistic simulations are particularly adapted to\ninvestigate the core structure or mobility of individual dislocations, while\ncontinuous approaches can simulate the complete and continuous mechanical\nbehaviour at the scale of the components. the purpose of DDD is to simulate the\nevolution of large dislocation ensembles in reaction to an external load and to\nassess the collective behaviour of dislocations.",
        "positive": "Electron Paramagnetic Resonance of $V_{N}-V_{Ga}$ complex in $BGaN$: Metastable photoinduced Electron Paramagnetic Resonance (EPR) signal at low\ntemperatures is reported in GaN alloyed with boron ($B_{x}Ga_{1-x}N$) epitaxial\nlayers grown at temperatures ranging from 840 {\\deg}C to 1090 {\\deg}C. An\nisotropic EPR line with g = 2.004 is observed with intensity depending on the\ngrowth temperature for all samples with boron content between 0.73% and 2.51%.\nTemperature dependence of EPR intensities is compared with the results of\nHigh-Resolution Photoinduced Transient Spectroscopy (HRPITS). This allows to\nlink particular traps with EPR signal. The activation energies of these traps\nare consistent with the theoretical position of the $V_{N}-V_{Ga}$ complex.\nThermal annihilation of the EPR signal with 30 meV activation energy\ncorresponds to shallow donor ionization. The model explaining light-induced EPR\nsignal involving redistribution of electrons between deep and shallow donors\nmediated by photoionization to the conduction band is proposed."
    },
    {
        "anchor": "Imaging the buried MgO/Ag interface: formation mechanism of the STM\n  contrast: Scanning tunneling microscopy (STM) provides real-space electronic state\ninformation at the atomic scale that is most commonly used to study materials\nsurfaces. An intriguing extension of the method is attempt to study the\nelectronic structure at an insulator/conductor interface by performing low-bias\nimaging above the surface of an ultrathin insulating layer on the conducting\nsubstrate. We use first-principles theory to examine the physical mechanisms\ngiving rise to the formation of low-bias STM images in the MgO/Ag system. We\nshow that the main features of the low-bias STM contrast are completely\ndetermined by the atoms on the surface of MgO. Hence, the low-bias contrast is\nformed by states at the Fermi level in the Ag that propagate evanescently\nthrough the lattice and atomic orbitals of the MgO on their way to the surface.\nWe develop a number of analysis techniques based on an ab initio tight-binding\nrepresentation that allow identification of the origin of the STM contrast in\ncases where previous approaches have proven ambiguous.",
        "positive": "Structural, Electronic and Magnetic Properties of Bulk and Epitaxial\n  LaCoO$_3$ through Diffusion Monte Carlo: Magnetism in lanthanum cobaltite (LCO, LaCoO$_3$) appears to be strongly\ndependent on strain, defects, and nanostructuring. LCO on strontium titanate\n(STO, SrTiO$_3$) is a ferromagnet with an interesting strain relaxation\nmechanism that yields a lattice modulation. However, the driving force of the\nferromagnetism is still controversial. Experiments debate between a\nvacancy-driven or strain-driven mechanism for the ferromagnetism of epitaxial\nLCO. We found that a weak lateral modulation of the superstructure is\nsufficient to promote ferromagnetism. We find that ferromagnetism appears under\nuniaxial compression and expansion. Although earlier experiments suggest that\nbulk LCO is nonmagnetic, we find an antiferromagnetic ground state for bulk\nLCO. We discuss the recent experiments which indicate a more complicated\npicture for bulk magnetism and a closer agreement with our calculations. Role\nof defects are also discussed through excited state calculations."
    },
    {
        "anchor": "Probing the Electron States and Metal-Insulator Transition Mechanisms in\n  Atomically Thin MoS2 Based on Vertical Heterostructures: The metal-insulator transition (MIT) is one of the remarkable electrical\ntransport properties of atomically thin molybdenum disulphide (MoS2). Although\nthe theory of electron-electron interactions has been used in modeling the MIT\nphenomena in MoS2, the underlying mechanism and detailed MIT process still\nremain largely unexplored. Here, we demonstrate that the vertical\nmetal-insulator-semiconductor (MIS) heterostructures built from atomically thin\nMoS2 (monolayers and multilayers) are ideal capacitor structures for probing\nthe electron states in MoS2. The vertical configuration of MIS heterostructures\noffers the added advantage of eliminating the influence of large impedance at\nthe band tails and allows the observation of fully excited electron states near\nthe surface of MoS2 over a wide excitation frequency (100 Hz-1 MHz) and\ntemperature range (2 K- 300 K). By combining capacitance and transport\nmeasurements, we have observed a percolation-type MIT, driven by density\ninhomogeneities of electron states, in the vertical heterostructures built from\nmonolayer and multilayer MoS2. In addition, the valence band of thin MoS2\nlayers and their intrinsic properties such as thickness-dependence screening\nabilities and band gap widths can be easily accessed and precisely determined\nthrough the vertical heterostructures.",
        "positive": "Bridging atomistic spin dynamics methods and phenomenological models of\n  single pulse ultrafast switching in ferrimagnets: We bridge an essential knowledge gap on the understanding of all-optical\nultrafast switching in ferrimagnets; namely, the connection between atomistic\nspin dynamics methods and macroscopic phenomenological models. All-optical\nswitching of the magnetization occurs after the application of a single\nfemtosecond laser pulse to specific ferrimagnetic compounds. This strong\nexcitation puts the involved degrees of freedom, electrons, lattice and spins\nout-of-equilibrium between each other. Atomistic spin models have\nquantitatively described all-optical switching in a wide range of experimental\nconditions, while having failed to provide a simple picture of the switching\nprocess. Phenomenological models are able to qualitatively describe the\ndynamics of the switching process. However, a unified theoretical framework is\nmissing that describes the element-specific spin dynamics as atomistic spin\nmodels with the simplicity of phenomenology. Here, we bridge this gap and\npresent an element-specific macrospin dynamical model which fully agrees with\natomistic spin dynamics simulations and symmetry considerations of the\nphenomenological models."
    },
    {
        "anchor": "Hydraulically Amplified Self-Healing ELectrostatic (HASEL) Inspired\n  Actuators: This report presents research conducted on amplified self-healing\nelectrostatic (HASEL) actuators. HASEL actuators are comprised of a dielectric\nfluid sealed between two inextensible layers with bonded, flexible electrodes\non its outer surface. When charge is applied to the electrodes, Coulomb force\ncompresses the fluid and causes the actuator to contract. In this work a\nfaster, more customizable and convenient way of creating a HASEL actuator is\npresented, using a laser engraver to heat-seal and cut polypropylene sheets.\nUsing this technique, a hydraulically actuated soft lens is fabricated and\ndemonstrated.",
        "positive": "Recent Advances in Two-Dimensional Metal Monochalcogenides: The family of emerging low-symmetry and structural in-plane anisotropic 2D\nmaterials have been expanding rapidly in recent years. As an important emerging\nanisotropic 2D material, the black phosphorene (BP) analog group IVA-VI metal\nmonochalcogenides (MMCs) have been surged recently due to their distinctive\ncrystalline symmetries, exotic in-plane anisotropic electronic and optical\nresponse, earth abundant and environmentally friendly characteristics. In this\narticle, we review the recent research advancements in the field of anisotropic\n2D MMCs. At first, the unique wavy crystal structures together with the optical\nand electronic properties of such materials are discussed. The review continues\nwith the various methods adopted for the synthesis of layered MMCs including\nmicromechanical and liquid phase exfoliation as well as physical vapor\ndeposition. The last part of the article focuses on the application of the\nstructural anisotropic response of 2D MMCs in field effect transistors,\nphotovoltaic cells nonlinear optics and valleytronic devices. Besides\npresenting the significant research in the field of this emerging class of 2D\nmaterials, this review also delineates the existing limitations and discusses\nemerging possibilities and future prospects."
    },
    {
        "anchor": "2D MXenes: Visible Black but Infrared White Materials: Black materials with low infrared absorption/emission (or IR white) are rare\nin nature but highly desired in numerous areas, such as solar-thermal energy\nharvesting, multispectral camouflage, thermal insulation, and\nanti-counterfeiting. Due to the lack of spectral selectivity in intrinsic\nmaterials, such counter-intuitive properties are generally realized by\nconstructing complicated subwavelength metamaterials with costly\nnanofabrication techniques. Here we report the low mid-IR emissivity (down to\n10%) of 2D Ti3C2Tx MXenes. Associated with a high solar absorptance (up to\n90%), they embrace the best spectral selectivity among the reported intrinsic\nblack solar absorbing materials. Their appealing potentials in several\naforementioned areas are experimentally demonstrated. First-principles\ncalculations reveal that the IR emissivity of MXenes relies on both the\nnanoflake orientations and terminal groups, indicating great tunability. The\ncalculations also suggest that more MXenes including Ti2CTx, Nb2CTx, and V2CTx\nare also potential low-emissivity materials. This work opens the avenue to\nfurther exploration of a family of intrinsically low-emissivity materials with\nover 70 members.",
        "positive": "Intermittent stick-slip dynamics during the peeling of an adhesive tape\n  from a roller: We study experimentally the fracture dynamics during the peeling at a\nconstant velocity of a roller adhesive tape mounted on a freely rotating\npulley. Thanks to a high speed camera, we measure, in an intermediate range of\npeeling velocities, high frequency oscillations between phases of slow and\nrapid propagation of the peeling fracture. This so-called stick-slip regime is\nwell known as the consequence of a decreasing fracture energy of the adhesive\nin a certain range of peeling velocity coupled to the elasticity of the peeled\ntape. Simultaneously with stick-slip, we observe low frequency oscillations of\nthe adhesive roller angular velocity which are the consequence of a pendular\ninstability of the roller submitted to the peeling force. The stick-slip\ndynamics is shown to become intermittent due to these slow pendular\noscillations which produce a quasi-static oscillation of the peeling angle\nwhile keeping constant the peeling fracture velocity (averaged over each\nstick-slip cycle). The observed correlation between the mean peeling angle and\nthe stick-slip amplitude questions the validity of the usually admitted\nindependence with the peeling angle of the fracture energy of adhesives."
    },
    {
        "anchor": "The design and the performance of an ultrahigh vacuum 3He fridge-based\n  scanning tunneling microscope with a double deck sample stage for in-situ tip\n  treatment: Scanning tunneling microscope (STM) is a powerful tool for studying the\nstructural and electronic properties of materials at the atomic scale. The\ncombination of low temperature and high magnetic field for STM and related\nspectroscopy techniques allows us to investigate the novel physical properties\nof materials at these extreme conditions with high energy resolution. Here, we\npresent the construction and the performance of an ultrahigh vacuum 3He\nfridge-based STM system with a 7 Tesla superconducting magnet. It features a\ndouble deck sample stage on the STM head so we can clean the tip by field\nemission or prepare a spin-polarized tip in situ without removing the sample\nfrom the STM. It is also capable of in situ sample and tip exchange and\npreparation. The energy resolution of scanning tunneling spectroscopy at T =\n310 mK is determined to be 400 mK by measuring the superconducting gap with a\nniobium tip on a gold surface. We demonstrate the performance of this STM\nsystem by imaging the bicollinear magnetic order of $Fe_{1+x}Te$ at T=5K.",
        "positive": "Revealing Hidden Orbital Pseudospin Texture with Time-Reversal Dichroism\n  in Photoelectron Angular Distributions: We performed angle-resolved photoemission spectroscopy (ARPES) of bulk\n2H-WSe$_2$ for different crystal orientations linked to each other by\ntime-reversal symmetry. We introduce a new observable called time-reversal\ndichroism in photoelectron angular distributions (TRDAD), which quantifies the\nmodulation of the photoemission intensity upon effective time-reversal\noperation. We demonstrate that the hidden orbital pseudospin texture leaves its\nimprint onto TRDAD, due to multiple orbitals interference effects in\nphotoemission. Our experimental results are in quantitative agreement with both\ntight-binding model and state-of-the-art fully relativistic calculations\nperformed using the one-step model of photoemission. While spin-resolved ARPES\nprobes the spin component of entangled spin-orbital texture in multiorbital\nsystems, we unambiguously demonstrate that TRDAD reveals its orbital pseudospin\ntexture counterpart."
    },
    {
        "anchor": "Electronic structure and photo absorption property of pseudo-cubic\n  perovskites CH$_3$NH$_3$PbX$_3$ (X=I, Br) including van der Waals interaction: Using density functional theory with the inclusion of van der Waals (vdW)\ninteraction, we have investigated electronic energy bands, density of states,\neffective masses of charge carriers, and photo absorption coefficients of\npseudo-cubic CH$_3$NH$_3$PbX$_3$ (X=I, Br). Our results confirm the direct\nbandgap of 1.49 (1.92) eV for X=I (Br) in the pseudo-cubic $Pm$ phase with\nlattice constant of 6.324 (5.966) \\AA, being agreed well with experiment and\nindicating the necessity of vdW correction. The calculated photo absorption\ncoefficients for X=I (Br) have the onset at red (orange) color and the first\npeak around violet (ultraviolet) color in overall agreement with the\nexperiment.",
        "positive": "Electronic thermal conductivity as derived by density functional theory: Reliable evaluation of the lattice thermal conductivity is of importance for\noptimizing the figure-of-merit of thermoelectric materials. Traditionally, when\nderiving the phonon mediated thermal conductivity $\\kappa_{ph} = \\kappa -\n\\kappa_{el}$ from the measured total thermal conductivity $\\kappa$ the constant\nLorenz number $L_0$ of the Wiedemann-Franz law \\mbox{$\\mathbf{\\kappa_{el}}=T\nL_0 \\sigma$} is chosen. The present study demonstrates that this procedure is\nnot reliable when the Seebeck coefficient $|S|$ becomes large which is exactly\nthe case for a thermoelectric material of interest. Another approximation using\n$L_0-S^2$, which seem to work better for medium values of $S^2$ also fails when\n$S^2$ becomes large, as is the case when the system becomes\nsemiconducting/insulating. For a reliable estimation of $\\kappa_{el}$ it is\nproposed, that a full first-principles calculations by combining density\nfunctional theory with Boltzmann's transport theory has to be made. For the\npresent study such an approach was chosen for investigating the clathrate\ntype-I compound Ba$_8$Au$_{6-x}$Ge$_{40+x}$ for a series of dopings or\ncompositions $x$. For a doping of $0.8$ electrons corresponding to $x=0.27$ the\ncalculated temperature dependent Seebeck coefficient agrees well with recent\nexperiments corroborating the validity of the density functional theory\napproach."
    },
    {
        "anchor": "Operando X-ray characterization of interfacial charge transfer and\n  structural rearrangements: Key technologies in energy conversion and storage, sensing and chemical\nsynthesis rely on a detailed knowledge about charge transfer processes at\nelectrified solid-liquid interfaces. However, these interfaces continuously\nevolve as a function of applied potentials, ionic concentrations and time. We\ntherefore need to characterize chemical composition, atomic arrangement and\nelectronic structure of both the liquid and the solid side of the interface\nunder operating conditions. In this chapter, we discuss the state-of-the-art\nX-ray based spectroscopy and diffraction approaches for such 'operando'\ncharacterization. We highlight recent examples from literature and demonstrate\nhow X-ray absorption spectroscopy, X-ray photoelectron spectroscopy and surface\nX-ray diffraction can reveal the required interface-sensitive information.",
        "positive": "Structural and transport properties of 4f electron doped Y1-x(Dy)xPdBi\n  topological semi-metallic thin films: We report the effect of 4f electron doping on structural, electrical and\nmagneto-transport properties of Dy doped half Heusler Y1-x(Dy)xPdBi (x =0, 0.2,\n0.5, 1) thin films grown by pulsed laser deposition. The Dy doping leads to\nlattice contraction which increases from 0% for the parent x =0 sample to\napprox 1.3% for x=1 sample with increase in Dy doping. The electrical transport\nmeasurements show a typical semi-metallic behaviour in the temperature range 3K\nto 300K and a sharp drop in resistivity at low temperatures (less than 3K) for\nall the samples. Magnetotransport measurements and Shubnikov de-Hass\noscillations at high magnetic fields demonstrate that for these topologically\nnon-trivial samples, Dy doping induced lattice contraction plays an active role\nin modifying the Fermi surface, carrier concentration and the effective\nelectron mass. There is an uniform suppression of the onset of\nsuperconductivity with increased Dy doping which is possibly related to the\nincreasing local exchange field arising from the 4f electrons in Dy. Our\nresults indicate that we can tune various band structure parameters of YPdBi by\nf electron doping and strained thin films of Y1-x(Dy)xPdBi show surface\ndominated relativistic carrier transport at low temperatures."
    },
    {
        "anchor": "Resonant Raman of OH/OD vibrations and photoluminescence studies in\n  LiTaO3 thin film: Resonant Raman spectra (RRS) of O-H and O-D vibration and libration modes,\ntheir combinations and higher harmonics have been observed in LiTaO3\npolycrystalline thin films. RRS peaks are superimposed on photoluminescence\n(PL) spectrum. Monochromatic light from a xenon lamp is used as excitation\nsource. PL spectrum shows two broad peaks, first near the band gap in UV\n(4.4-4.8eV) and another in the sub band gap region (< 4.0 eV). Band gap PL\nalong with RRS peaks are reported for the first time. Photoluminescence\nexcitation spectrum (PLE) shows a peak at 4.8 eV. Peak positions and full width\nat half maximum (FWHM) of RRS peaks depend upon the excitation energy.\nDispersions of the fundamental and the third harmonic of the stretching mode of\nO-H with excitation energy are about 800 cm-1/eV and 2000 cm-1/eV respectively.\nThis dispersion is much higher than reported in any other material.",
        "positive": "Asymmetric pulsing for reliable operation of titanium/manganite\n  memristors: We present a pulsing protocol that significantly increases the endurance of a\ntitanium-manganite interface used as a binary memory cell. The core of this\nprotocol is an algorithm that searches for the proper values for the set and\nreset pulses, canceling the drift in the resistance values. A set of\nexperiments show the drift-free operation for more than $10^{5}$ switching\ncycles, as well as the detrimental effect by changing the amplitude of pulses\nindicated by the protocol. We reproduced the results with a numerical model,\nwhich provides information on the dynamics of the oxygen vacancies during the\nswitching cycles."
    },
    {
        "anchor": "Two-Dimensional Arsenene Oxide: A Realistic Large-gap Quantum Spin Hall\n  Insulator: Searching for two-dimensional (2D) realistic materials able to realize\nroom-temperature quantum spin Hall (QSH) effects is currently a growing field.\nHere, we through ab initio calculations to identify arsenene oxide, AsO, as an\nexcellent candidate, which demonstrates high stability, flexibility, and\ntunable spin-orbit coupling (SOC) gaps. In contrast to known pristine or\nfunctionalized arsenene, the maximum nontrivial band gap of AsO reaches 89 meV,\nand can be further enhanced to 130 meV under biaxial strain. By sandwiching 2D\nAsO between BN sheets, we propose a quantum well in which the band topology of\nAsO is preserved with a sizeable band gap. Considering that AsO having fully\noxidized surfaces are naturally stable against surface oxidization and\ndegradation, this functionality provides a viable strategy for designing\ntopological quantum devices operating at room temperature.",
        "positive": "Surface structure and solidification morphology of aluminum nanoclusters: Classical molecular dynamics simulation with embedded atom method potential\nhad been performed to investigate the surface structure and solidification\nmorphology of aluminum nanoclusters Aln (n = 256, 604, 1220 and 2048). It is\nfound that Al cluster surfaces are comprised of (111) and (001) crystal planes.\n(110) crystal plane is not found on Al cluster surfaces in our simulation. On\nthe surfaces of smaller Al clusters (n = 256 and 604), (111) crystal planes are\ndominant. On larger Al clusters (n = 1220 and 2048), (111) planes are still\ndominant but (001) planes can not be neglected. Atomic density on cluster\n(111)/(001) surface is smaller/larger than the corresponding value on bulk\nsurface. Computational analysis on total surface area and surface energies\nindicates that the total surface energy of an ideal Al nanocluster has the\nminimum value when (001) planes occupy 25% of the total surface area. We\npredict that a melted Al cluster will be a truncated octahedron after\nequilibrium solidification."
    },
    {
        "anchor": "Dependence of electronic polarization on octahedral rotations in TbMnO3\n  from first principles: The electronic contribution to the magnetically induced polarization in\northorhombic TbMnO3 is studied from first principles. We compare the cases in\nwhich the spin cycloid, which induces the electric polarization via the\nspin-orbit interaction, is in either the b-c or a-b plane. We find that the\nelectronic contribution is negligible in the first case, but much larger, and\ncomparable to the lattice-mediated contribution, in the second case. However,\nwe how that this behavior is an artifact of the particular pattern of\noctahedral rotations characterizing the structurally relaxed Pbnm crystal\nstructure. To do so, we explore how the electronic contribution varies for a\nstructural model of rigidly rotated MnO6 octahedra, and demonstrate that it can\nvary over a wide range, comparable with the lattice-mediated contribution, for\nboth b-c and a-b spirals. We introduce a phenomenological model that is capable\nof describing this behavior in terms of sums of symmetry-constrained\ncontributions arising from the displacements of oxygen atoms from the centers\nof the Mn-Mn bonds.",
        "positive": "Quantitative strain-field measurement of 1:1 B-site cation ordered\n  domains and antiphase boundaries in Pb(Sc1/2Ta1/2)O3 ceramics by\n  high-resolution transmission electron microscopy: Quantitative strain measurements of the 1:1 B-site cation ordered domains,\nantiphase boundaries and dislocations in a highly ordered Pb(Sc1/2Ta1/2)O3\nceramic have been carried out by high-resolution transmission electron\nmicroscopy and geometric phase analysis. A phase shift of PI between two\nadjacent ordered domains across an antiphase boundary are determined\nunambiguously. The maximum in-plane strain and lattice rotation induced by a\ndislocation are 9.5% and 5.4deg, respectively. In a defect-free antiphase\nboundary, the maximum in-plane strain and lattice rotation are 1.8% and 0.9deg,\nrespectively. The strain mainly concentrates inside the antiphase boundary."
    },
    {
        "anchor": "A First-Principles Study on the Adsorption of Small Molecules on\n  Antimonene: Oxidation Tendency and Stability: Antimonene, a new group-VA 2D semiconducting material beyond phosphorene, was\nrecently synthesized through various approaches and was shown to exhibit a good\nstructural integrity in ambient conditions and various interesting properties.\nIn this work, we perform systematical first-principles investigations on the\ninteractions of antimonene with the small molecules CO, NO, NO2, H2O, O2, NH3\nand H2. It is found that NO, NO2, H2O, O2, and NH3 serve as charge acceptors,\nwhile CO shows a negligible charge transfer. H2 acts as a charge donor to\nantimonene with the amount of charge transfer being ten times that of H2 on\nphosphorene. The interaction of the O2 molecule with antimonene is much\nstronger than that with phosphorene. Surprisingly, the kinetic barrier for the\nsplitting of the O2 molecule on antimonene is low (~0.40 eV), suggesting that\npristine antimonene may undergo oxidation in ambient conditions, especially at\nelevated temperatures. Fortunately, the acceptor role of H2O on antimonene,\nopposite to a donor role in phosphorene, helps to suppress further structural\ndegradation of the oxidized antimonene by preventing the proton transfer\nbetween water molecules and oxygen species to form acids.",
        "positive": "Ab initio and Molecular Dynamics Study of the Nanomechanical Properties\n  of DNA Oligomers: Although a vast amount of experimental information is available on the\nelongation, compression, and folding of proteins in biochemical processes, very\nlittle is known about the real structure and molecular dynamics of DNA at an\natomic level. Since this area of work is relatively new, this paper reports the\nresults of computer simulation of elongation and compression of B-DNA\nstructures providing new insights into high- energy forms of DNA implicated in\nthese processes."
    },
    {
        "anchor": "Model of surface instabilities induced by stress: We propose a model based on a Ginzburg-Landau approach to study a strain\nrelief mechanism at a free interface of a non-hydrostatically stressed solid,\ncommonly observed in thin-film growth. The evolving instability, known as the\nGrinfeld instability, is studied numerically in two and three dimensions.\nInherent in the description is the proper treatment of nonlinearities. We find\nthese nonlinearities can lead to competitive coarsening of interfacial\nstructures, corresponding to different wavenumbers, as strain is relieved. We\nsuggest ways to experimentally measure this coarsening.",
        "positive": "Structural properties of amorphous metal carbides; theory and experiment: By means of theoretical modeling and experimental synthesis and\ncharacterization, we investigate the structural properties of amorphous\nZr-Si-C. Two chemical compositions are selected, Zr0.31Si0.29C0.40 and\nZr0.60Si0.33C0.07. The amorphous structures are generated in the theoretical\npart of our work, by the stochastic quenching (SQ) method, and detailed\ncomparison is made as regards structure and density of the experimentally\nsynthesized films. These films are analyzed experimentally using X-ray\nabsorption spectroscopy, transmission electron microscopy and X-ray\ndiffraction. Our results demonstrate for the first time a remarkable agreement\nbetween theory and experiment concerning bond distances and atomic coordination\nof this complex amorphous metal carbide. The demonstrated power of the SQ\nmethod opens up avenues for theoretical predictions of amorphous materials in\ngeneral."
    },
    {
        "anchor": "Power law load dependence of atomic friction: We present a theoretical study of the dynamics of a tip scanning a graphite\nsurface as a function of the applied load. From the analysis of the lateral\nforces, we extract the friction force and the corrugation of the effective\ntip-surface interaction potential. We find both the friction force and\npotential amplitude to have a power law dependence on applied load with\nexponent $\\sim 1.6$. We interpret these results as characteristic of sharp\nundeformable tips in contrast to the case of macroscopic and elastic\nmicroscopic contacts.",
        "positive": "Unraveling the role of V-V dimer on the vibrational properties of VO$_2$\n  by first-principles simulations and Raman spectroscopic analysis: We investigate the vibrational properties of VO2, particularly the low\ntemperature M1 phase by first-principles calculations using the density\nfunctional theory as well as Raman spectroscopy. We perform the structural\noptimization using SCAN meta-GGA functional and obtain the optimized crystal\nstructures for metallic rutile and insulating M1 phases satisfying all expected\nfeatures of the experimentally derived structures. Based on the harmonic\napproximation around the optimized structures at zero temperature, we calculate\nthe phonon properties and compare our results with experiments. We show that\nour calculated phonon density of states is in excellent agreement with the\nprevious neutron scattering experiment. Moreover, we reproduce the phonon\nsoftening in the rutile phase as well as the phonon stiffening in the M1 phase.\nBy comparing with the Raman experiments, we find that the Raman-active\nvibration modes of the M1 phase is strongly correlated with the V-V dimer\ndistance of the crystal structure. Our combined theoretical and experimental\nframework demonstrates that Raman spectroscopy could serve as a reliable way to\ndetect the subtle change of V-V dimer in the strained VO$_2$."
    },
    {
        "anchor": "Ionic partition and transport in multi-ionic channels: A Molecular\n  Dynamics Simulation study of the OmpF bacterial porin: We performed all-atom molecular dynamics simulations studying the partition\nof ions and the ionic current through the bacterial porin OmpF and two selected\nmutants. The study is motivated by new interesting experimental findings\nconcerning their selectivity and conductance behaviour at neutral pH. The\nmutations considered here are designed to study the effect of removal of\nnegative charges present in the constriction zone of the wild type OmpF channel\n(which contains on one side a cluster with three positive residues and on the\nother side two negatively charged residues). Our results show that these\nmutations induce an exclusion of cations from the constriction zone of the\nchannel, substantially reducing the flow of cations. In fact, the partition of\nions inside the mutant channels is strongly inhomogeneous, with regions\ncontaining excess of cations and regions containing excess of anions.\nInterestingly, the overall number of cations inside the channel is larger than\nthe number of anions in the two mutants, as in the OmpF wild type channel. We\nfound that the differences in ionic charge inside these channels are justified\nby the differences in electric charge between the wild type OmpF and the\nmutants, following an electroneutral balance.",
        "positive": "Thermoelectric imaging of structural disorder in epitaxial graphene: Heat is a familiar form of energy transported from a hot side to a colder\nside of an object, but not a notion associated with microscopic measurements of\nelectronic properties. A temperature difference within a material causes charge\ncarriers, electrons or holes, to diffuse along the temperature gradient\ninducing a thermoelectric voltage. Here we show that local thermoelectric\nmeasurements can yield high sensitivity imaging of structural disorder on the\natomic and nanometre scales. The thermopower measurement acts to amplify the\nvariations in the local density of states at the Fermi-level, giving high\ndifferential contrast in thermoelectric signals. Using this imaging technique,\nwe uncovered point defects in the first layer of epitaxial graphene, which\ngenerate soliton-like domain wall line patterns separating regions of the\ndifferent interlayer stacking of the second graphene layer."
    },
    {
        "anchor": "A multi-scale approach to the electronic structure of doped\n  semiconductor surfaces: The inclusion of the global effects of semiconductor doping poses a unique\nchallenge for first-principles simulations, because the typically low\nconcentration of dopants renders an explicit treatment intractable. In systems\nwhich do not display long-range band bending, a satisfactory remedy is offered\nby the use of \"pseudoatoms\", with a fractional nuclear charge matching the bulk\ndoping concentration. However, this alone is not always sufficient for charged\nsurfaces, where the width of the space-charge region (SCR) often exceeds\nrealistic supercell dimensions. One generalization of the pseudoatom approach\nwhich overcomes this difficulty relies on the introduction of an artificially\nhigh doping level within a slab calculation, in conjunction with a multi-scale\nelectrostatic energy correction. Here, we present an alternative technique that\nnaturally extends the pseudoatom approach while bypassing the need for\ncalculations with an unrealistically high doping level. It is based on the\nintroduction of excess charge, mimicking free charge carriers from the SCR,\nalong with a fixed sheet of counter-charge mimicking the SCR-related field.\nSelf-consistency is obtained by imposing charge conservation and Fermi level\nequilibration between the bulk, treated semi-classically, and the electronic\nstates of the slab/surface, which are treated quantum-mechanically. The method,\nwhich we call CREST - the Charge-Reservoir Electrostatic Sheet Technique - can\nbe used with standard electronic structure codes. We validate the approach\nusing a simple tight-binding model, which allows for comparison of its results\nwith calculations encompassing the full SCR explicitly. We then employ it with\ndensity functional theory, where it is used to obtain insights into the\nelectronic structures of the \"clean-cleaved\" Si(111) surface and its buckled\n(2x1) reconstruction, at various doping densities.",
        "positive": "Effect of strain on the stability and electronic properties of\n  ferrimagnetic Fe$_{2-x}$Ti$_x$O$_3$ heterostructures from correlated band\n  theory: Based on density functional theory (DFT) calculations including an on-site\nHubbard $U$ term we investigate the effect of substrate-induced strain on the\nproperties of ferrimagnetic Fe$_2$O$_3$-FeTiO$_3$ solid solutions and\nheterostructures. While the charge compensation mechanism through formation of\na mixed \\fetw, \\feth-contact layer is unaffected, strain can be used to tune\nthe electronic properties of the system, e.g. by changing the position of\nimpurity levels in the band gap. Straining hematite/ilmenite films at the\nlateral parameters of Al$_{2}$O$_{3}$(0001), commonly used as a substrate, is\nfound to be energetically unfavorable as compared to films on\nFe$_{2}$O$_{3}$(0001) or FeTiO$_{3}$(0001)-substrates."
    },
    {
        "anchor": "Microstructural Characterization and Mechanical Property Evaluation of\n  High Nitrogen Martensitic Stainless Steel Subjected to Heat Treatment: The High Nitrogen Martensitic Stainless Steel (HNMS) was subjected to three\ndifferent austenitizing cycles of 1050$^\\circ$C, 1075$^\\circ$C and\n1100$^\\circ$C followed by subzero treatment at -70$^\\circ$C. The fraction of\nretained austenite has been reduced after sub-zero treatment as revealed by\nmicrostructural evolution. The material was subsequently tempered at different\ntemperatures ranging from 180$^\\circ$C to 650$^\\circ$C and the change in\nmicro-structure, hardness, tensile strength and toughness were investigated\nafter each heat treatment cycle. Optical microscopy, electron microscopy with\nEDS and X-Ray diffraction techniques were used to characterize the material.\nThis has showed the constituents of microstructure were lath martensite,\nprecipitated metal carbides of type $M_{23}C_6$, $M_7C_6$ and carbo-nitrides.\nHardness, tensile testing and Charpy impact testing were carried to evaluate\nmechanical properties after the heat treatment which has showed the better\nmechanical properties for the samples solutionised at 1075$^\\circ$C. Secondary\nhardening has been observed on tempering above 450$^\\circ$C which can be\nattributed to the precipitation of secondary phase inter-metallic compounds.\nHardness attains a peak value at peculiar temperature range after which it\ndecreases on further tempering which is most likely because of the loss of\ncoherency of the precipitates with the metal matrix. This has been further\nconfirmed by the XRD of the specimens before and after tempering. The study\nstablishes the structure-property correlation of HNMS for different heat\ntreatment cycles. The results indicate that a good combination of hardness and\nstrength can be achieved after solutionizing at 1075$^\\circ$C followed by\ndouble tempering at 525$^\\circ$C.",
        "positive": "Speed limits of the laser-induced phase transition in FeRh: We use ultrafast x-ray diffraction (UXRD) and the polar time-resolved\nmagneto-optical Kerr effect (tr-MOKE) to study the laser-induced metamagnetic\nphase transition in two FeRh films with thicknesses below and above the optical\npenetration depth. In the thin film, we identify an intrinsic timescale for the\nlight-induced nucleation of ferromagnetic (FM) domains in the antiferromagnetic\nmaterial of $8\\,\\text{ps}$ that is substantially slower than the speed of\nsound. For the inhomogeneously excited thicker film, only the optically excited\nnear-surface part transforms within $8\\,\\text{ps}$. For strong excitations we\nobserve an additional slow rise of the FM phase, which we experimentally relate\nto a growth of the FM phase into the depth of the layer by comparing the\ntransient magnetization in front- and backside excitation geometry. In the\nlower lying parts of the film, which are only excited via near-equilibrium heat\ntransport, the FM phase emerges significantly slower than $8\\,\\text{ps}$ after\nheating above the transition temperature."
    },
    {
        "anchor": "Complex Quasi-Two-Dimensional Crystalline Order Embedded in VO$_2$ and\n  Other Crystals: Metal oxides such as VO$_2$ undergo structural transitions to low-symmetry\nphases characterized by intricate crystalline order, accompanied by rich\nelectronic behavior. We derive a minimal ionic Hamiltonian based on symmetry\nand local energetics which describes structural transitions involving all four\nobserved phases, in the correct order. An exact analysis shows that complexity\nresults from the symmetry-induced constraints of the parent phase which forces\nionic displacements to form multiple interpenetrating groups using\nlow-dimensional pathways and distant neighbors. Displacements within each group\nexhibit independent, quasi two-dimensional order, which is frustrated and\nfragile. This selective ordering mechanism is not restricted to VO$_2$: it\napplies to other oxides which show similar complex order.",
        "positive": "Adsorption of NO2 on WSe2: DFT and photoelectron spectroscopy studies: The electronic structure modifications of WSe2 upon NO2-adsorption at room\nand low temperatures were studied by means of photoelectron spectroscopy. We\nfound only moderate changes in the electronic structure, which are manifested\nas an upward shift of the WSe2-related bands to the smaller binding energies.\nThe observed effects are modelled within the density functional theory\napproach, where a weak adsorption energy of gas molecules on the surface of\nWSe2 was deduced. The obtained experimental data are explained as a valence\nbands polarisation effect, which causes their energy shift depending on the\nadsorption geometry and the formed dipole moment."
    },
    {
        "anchor": "Ferroelectric and dielectric properties of Hf0.5Zr0.5O2 thin film near\n  morphotropic phase boundary: Recently, based on the phase-field modeling, it was predicted that Hf1-xZrxO2\n(HZO) exhibits the morphotropic phase boundary (MPB) in its compositional phase\ndiagram. Here, we investigate the effect of structural changes between\ntetragonal (t) and orthorhombic (o) phases on the ferroelectric and dielectric\nproperties of HZO films to probe the existence of MPB region. The structural\nanalysis show that by adjusting the ozone dosage during the atomic layer\ndeposition process and annealing conditions, different ratios of t- to o-phases\n(f_(t/o) ) were achieved which consequently affect the ferroelectric and\ndielectric properties of the samples. Polarization versus electric field\nmeasurements show a remarkable increase in ferroelectric characteristics (Pr\nand Ec) of the sample that contains the minimum t-phase fraction (f_(t/o)~\n0.04). This sample shows the lowest dielectric constant compared to the other\nsamples which is due to the formation of ferroelectric o-phase. The sample that\ncontains the maximum f_(t/o)~ 0.41 demonstrates the highest dielectric\nresponse. By adjusting the f_(t/o), a large dielectric constant of ~ 55 is\nachieved. Our study reveals a direct relation between f_(t/o) and dielectric\nconstant of HZO thin films which can be understood by considering the density\nof MPB region.",
        "positive": "Search for correlations between morphological characteristics and the\n  crystallite sizes in thin zinc oxide films: Size-property relations in plasma-modified ZnO thin films have been\ninvestigated as a function of plasma treatment duration. The correlations\nbetween crystallite sizes and the morphological characteristics of films have\nbeen extracted on the basis of the frontier computational analysis of the\nscanning probe microscope (SPM) data matrices. The nanocluster structure of\noxide films have been studied in detail with high accuracy. The strong\nplasma-induced changes in crystallite sizes have been interpreted as a\nsize-structure phase transition. Direct measurements of X-ray diffraction and\noptical transmittance spectra have confirmed the results obtained with\ncomputational approaches. The discovery size-morphology correlations in thin\noxide films might open new avenues ultimately leading towards deeper insight\ninto unsolved problems of evaluation of optimal technological conditions for\nthin oxide film designing."
    },
    {
        "anchor": "Lattice specific heat for the RMIn$_5$ (R = Gd, La, Y, M = Co, Rh)\n  compounds: non-magnetic contribution subtraction: We analyze theoretically a common experimental process used to obtain the\nmagnetic contribution to the specific heat of a given magnetic material. In the\nprocedure, the specific heat of a non-magnetic analog is measured and used to\nsubtract the non-magnetic contributions, which are generally dominated by the\nlattice degrees of freedom in a wide range of temperatures. We calculate the\nlattice contribution to the specific heat for the magnetic compounds GdMIn$_5$\n(M = Co, Rh) and for the non-magnetic YMIn$_5$ and LaMIn$_5$ (M = Co, Rh),\nusing density functional theory based methods. We find that the best\nnon-magnetic analog for the subtraction depends on the magnetic material and on\nthe range of temperatures. While the phonon specific heat contribution of\nYRhIn$_5$ is an excellent approximation to the one of GdCoIn$_5$ in the full\ntemperature range, for GdRhIn$_5$ we find a better agreement with LaCoIn$_5$,\nin both cases, as a result of an optimum compensation effect between masses and\nvolumes. We present measurements of the specific heat of the compounds\nGdMIn$_5$ (M = Co, Rh) up to room temperature where it surpasses the value\nexpected from the Dulong-Petit law. We obtain a good agreement between theory\nand experiment when we include anharmonic effects in the calculations.",
        "positive": "Magnetic domain wall propagation in a submicron spin-valve stripe:\n  influence of the pinned layer: The propagation of a domain wall in a submicron ferromagnetic spin-valve\nstripe is investigated using giant magnetoresistance. A notch in the stripe\nefficiently traps an injected wall stopping the domain propagation. The authors\nshow that the magnetic field at which the wall is depinned displays a\nstochastic nature. Moreover, the depinning statistics are significantly\ndifferent for head to head and tail-to-tail domain walls. This is attributed to\nthe dipolar field generated in the vicinity of the notch by the pinned layer of\nthe spin-valve."
    },
    {
        "anchor": "Potential 2D thermoelectric materials ATeI (A=Sb and Bi) monolayers from\n  a first-principles study: Lots of two-dimensional (2D) materials have been predicted theoretically, and\nfurther confirmed in experiment, which have wide applications in nanoscale\nelectronic, optoelectronic and thermoelectric devices. Here, the thermoelectric\nproperties of ATeI (A=Sb and Bi) monolayers are systematically investigated,\nbased on semiclassical Boltzmann transport theory. It is found that spin-orbit\ncoupling (SOC) has important effects on electronic transport coefficients in\np-type doping, but neglectful influences on n-type ones. The room-temperature\nsheet thermal conductance is 14.2 $\\mathrm{W K^{-1}}$ for SbTeI and 12.6\n$\\mathrm{W K^{-1}}$ for BiTeI, which are lower than one of most well-known 2D\nmaterials, such as transition-metal dichalcogenide, group IV-VI, group-VA and\ngroup-IV monolayers. By analyzing group velocities and phonon lifetimes, the\nvery low sheet thermal conductance of ATeI (A=Sb and Bi) monolayers is mainly\ndue to small group velocities. It is found that the high-frequency optical\nbranches contribute significantly to the total thermal conductivity, being\nobviously different from usual picture with little contribution from optical\nbranches. According to cumulative lattice thermal conductivity with respect to\nphonon mean free path (MFP), it is difficulty to further reduce lattice thermal\nconductivity by nanostructures. Finally, possible thermoelectric figure of\nmerit $ZT$ of ATeI (A=Sb and Bi) monolayers are calculated. It is found that\nthe p-type doping has more excellent thermoelectric properties than n-type\ndoping, and at room temperature, the peak $ZT$ can reach 1.11 for SbTeI and\n0.87 for BiTeI, respectively. These results make us believe that ATeI (A=Sb and\nBi) monolayers may be potential 2D thermoelectric materials, and can stimulate\nfurther experimental works to synthesize these monolayers.",
        "positive": "Large anomalous Hall, Nernst effect and topological phases in the\n  3d-4d/5d based oxide double perovskites: Magnetic topological quantum materials are attracting considerable attention\nowing to their potential technological applications. However, only a small\nnumber of these materials have been experimentally realized, thereby giving\nrise to the need for new stable magnetic topological quantum materials.\nMagnetism and spin-orbit coupling, two essential ingredients of the oxide\nmaterials, lead to various topological transport phenomena such as the\nanomalous Hall and anomalous Nernst effects, which can be significantly\nenhanced by designing an electronic structure with a large Berry curvature. In\nthat respect, double perovskites with the general formula A$_2$BB'O$_6$ with an\nalternating ordered arrangement of two transition metal sites, B(3d) and\nB'(4d/5d), present attractive possibilities as they are robustly stable against\noxidation under ambient conditions and versatile. These double perovskites also\noffer a high energy scale for magnetism as well as strong spin-orbit coupling\nwith a high magnetic ordering temperature. Here, using first-principles density\nfunctional theory calculations, we present a comprehensive study of the\nintrinsic anomalous transport for 3d-4d/5d based cubic and tetragonal stable\ndouble perovskite (DP) compounds. A few of the DPs exhibit a very large\nanomalous Hall effect with a distinct topological band crossing in the vicinity\nof the Fermi energy. Our results show the importance of symmetries,\nparticularly the mirror planes, as well as the clean topological band crossing\nnear the Fermi energy, which is primarily contributed by the 5d-t$_{2g}$ for\nlarge anomalous Hall and Nernst effects."
    },
    {
        "anchor": "Optical spectroscopy of trivalent chromium in sol-gel lithium niobate: We report on the characterization of sol-gel derived lithium niobate via\ntrivalent chromium probe ions, a study that is motivated by recent reports on\nthe synthesis of high quality sol-gel lithium niobate (LiNbO$_3$). In order to\nassess the quality of sol-gel derived LiNbO$_3$, we incorporate Cr$^{3+}$\nduring the hydrolysis stage of the sol-gel process. A comparison of the\nCr$^{3+}$ emission and photo-excitation data on both sol-gel and melt-grown\nLiNbO$_3$ shows that the sol-gel derived material is highly stoichiometric.",
        "positive": "A nonplanar Peierls-Nabarro model and its applications to dislocation\n  cross-slip: A novel semidiscrete Peierls-Nabarro model is introduced which can be used to\nstudy dislocation spreading at more than one slip planes, such as dislocation\ncross-slip and junctions. The strength of the model, when combined with ab\ninitio calculations for the energetics, is that it produces essentiallyan\natomistic simulation for dislocation core properties without suffering from the\nuncertainties associated with empirical potentials. Therefore, this method is\nparticularly useful in providing insight into alloy design when empirical\npotentials are not available or not reliable for such multi-element systems. As\nan example, we study dislocation cross-slip and constriction process in two\ncontrasting fcc metals, Al and Ag. We find that the screw dislocation in Al can\ncross-slip spontaneously in contrast with that in Ag, where the screw\ndislocation splits into two partials, which cannot cross-slip without first\nbeing constricted. The response of the dislocation to an external stress is\nexamined in detail. The dislocation constriction energy and the critical stress\nfor cross-slip are determined, and from the latter, we estimate the cross-slip\nenergy barrier for straight screw dislocations."
    },
    {
        "anchor": "Effect of spin-orbit coupling on the zero-point renormalization of the\n  electronic band gap in cubic materials: First-principles calculations and\n  generalized Fr\u00f6hlich model: The electronic structure of semiconductors and insulators is affected by\nionic motion through electron-phonon interaction, yielding\ntemperature-dependent band gap energies and zero-point renormalization (ZPR) at\nabsolute zero temperature. For polar materials, the most significant\ncontribution to the band gap ZPR can be understood in terms of the Fr\\\"ohlich\nmodel, which focuses on the nonadiabatic interaction between an electron and\nthe macroscopic electrical polarization created by a long-wavelength optical\nlongitudinal phonon mode. On the other hand, spin-orbit interaction (SOC)\nmodifies the bare electronic structure, which will, in turn, affect the\nelectron-phonon interaction and the ZPR. We present a comparative investigation\nof the effect of SOC on the band gap ZPR of twenty semiconductors and\ninsulators with cubic symmetry using first-principles calculations. We observe\na SOC-induced decrease of the ZPR, up to 30%, driven by the valence band edge,\nwhich almost entirely originates from the modification of the bare electronic\neigenenergies and the decrease of the hole effective masses near the $\\Gamma$\npoint. We also incorporate SOC into a generalized Fr\\\"ohlich model, addressing\nthe Dresselhaus splitting which occurs in noncentrosymmetric materials, and\nconfirm that the predominance of nonadiabatic effects on the band gap ZPR of\npolar materials is unchanged when including SOC. Our generalized Fr\\\"ohlich\nmodel with SOC provides a reliable estimate of the SOC-induced decrease of the\npolaron formation energy obtained from first principles and brings to light\nsome fundamental subtleties in the numerical evaluation of the effective masses\nwith SOC for noncentrosymmetric materials. We finally warn about a possible\nbreakdown of the parabolic approximation within the physically relevant energy\nrange of the Fr\\\"ohlich interaction for materials with high phonon frequencies\ntreated with SOC.",
        "positive": "Formation of fluorescent H aggregates of a cyanine dye in LB films and\n  its effect on energy transfer: Here we report the formation of fluorescent H aggregates of a cyanine dye\nOxa18 in ultrathin film and its effect on energy transfer between Oxa18 and\nsRhb. Ideally H aggregate do not fluoresce. However, due to imperfect stacking\nof Oxa18 molecules in the aggregates, fluorescence occurred from Oxa18 H\naggregates. This H aggregated band has substantial effect on the enhancement of\nenergy transfer from Oxa18 to sRhb both in solution and in ultrathin film."
    },
    {
        "anchor": "Quantum longitudinal and Hall transport at the LaAlO3/SrTiO3 interface\n  at low electron densities: We examined the magneto-transport behavior of electrons confined at the\nconducting LaAlO3/SrTiO3 interface in the low sheet carrier density regime. We\nobserved well resolved Shubnikov-de Haas quantum oscillations in the\nlongitudinal resistance, and a plateau-like structure in the Hall conductivity.\nThe Landau indices of the plateaus in the Hall conductivity data show spacing\nclose to 4, in units of the quantum of conductance. These experimental features\ncan be explained by a magnetic breakdown transition, which quantitatively\nexplains the area, structure, and degeneracy of the measured Fermi surface.",
        "positive": "Evidence for a pressure-induced phase transition of few-layer graphene\n  to 2D diamond: We unveil the diamondization mechanism of few-layer graphene compressed in\nthe presence of water, providing robust evidence for the pressure-induced\nformation of 2D diamond. High-pressure Raman spectroscopy provides evidence of\na phase transition occurring in the range of 4-7 GPa for 5-layer graphene and\ngraphite. The pressure-induced phase is partially transparent and indents the\nsilicon substrate. Our combined theoretical and experimental results indicate a\ngradual top-bottom diamondization mechanism, consistent with the formation of\ndiamondene, a 2D ferromagnetic semiconductor. High-pressure x-ray diffraction\non graphene indicates the formation of hexagonal diamond, consistent with the\nbulk limit of eclipsed-conformed diamondene."
    },
    {
        "anchor": "Giant enhanced optical nonlinearity of colloidal nanocrystals with a\n  graded-index host: The effective linear and third-order nonlinear optical properties of metallic\ncolloidal crystal immersed in a graded-index host fluid are investigated\ntheoretically. The local electric fields are extracted self-consistently based\non the layer-to-layer interactions, which are readily given by the Lekner\nsummation method. The resultant optical absorption and nonlinearity enhancement\nshow a series of sharp peaks, which merge in a broadened resonant band. The\nsharp peaks become a continuous band for increasing packing density and number\nof layers. We believe that the sharp peaks arise from the in-plane dipolar\ninteractions and the surface plasmon resonance, whereas the continuous band is\ndue to the presence of the gradient in the host refractive index. These results\nhave not been observed in homogeneous and randomly-dispersed colloids, and thus\nwould be of great interest in optical nanomaterial engineering.",
        "positive": "Revealing sub-\u03bcm inhomogeneities and \u03bcm-scale texture in H2O ice\n  at Megabar pressures via sound velocity measurements by time-domain Brillouin\n  scattering: Time-domain Brillouin scattering technique, also known as picosecond\nultrasonic interferometry, which provides opportunity to monitor propagation of\nnanometers to sub-micrometers length coherent acoustic pulses in the samples of\nsub-micrometers to tens of micrometers dimensions, was applied to\ndepth-profiling of polycrystalline aggregate of ice compressed in a diamond\nanvil cell to Megabar pressures. The technique allowed examination of\ncharacteristic dimensions of elastic inhomogeneities and texturing of\npolycrystalline ice in the direction normal to the diamond anvil surfaces with\nsub-micrometer spatial resolution via time-resolved measurements of variations\nin the propagation velocity of the acoustic pulse traveling in the compressed\nsample. The achieved two-dimensional imaging of the polycrystalline ice\naggregate in-depth and in one of the lateral directions indicates the\nfeasibility of three-dimensional imaging and quantitative characterization of\nacoustical, optical and acousto-optical properties of transparent\npolycrystalline aggregates in diamond anvil cell with tens of nanometers\nin-depth resolution and lateral spatial resolution controlled by pump laser\npulses focusing."
    },
    {
        "anchor": "Strain Solitons in an Epitaxially Strained van der Waals-like Material: Strain solitons are quasi-dislocations that form in van der Waals materials\nto relieve the energy associated with lattice or rotational mismatch in the\ncrystal. Novel and unusual electronic properties of strain solitons have been\nboth predicted and observed. To date, strain solitons have only been observed\nin exfoliated crystals or mechanically strained bulk crystals. The lack of a\nscalable approach towards the generation of strain solitons poses a significant\nchallenge in the study of and use of the properties of strain solitons. Here we\nreport the formation of strain solitons with epitaxial growth of bismuth on an\nInSb (111)B substrate by molecular beam epitaxy. The morphology of the strain\nsolitons for films of varying thickness is characterized with scanning\ntunneling microscopy and the local strain state is determined from the analysis\nof atomic resolution images. Bending in the solitons is attributed due to\ninteractions with the interface, and large angle bending is associated with\nedge dislocations. Our results enable the scalable generation of strain\nsolitons.",
        "positive": "On the Higgs mechanism and stress functions in the translational gauge\n  theory of dislocations: In this letter we discuss the Higgs mechanism in the linear and static\ntranslational gauge theory of dislocations. We investigate the role of the\nNambu-Goldstone field and the Proca field in the dislocation gauge theory. In\naddition, we give the constitutive relations for (homogeneous) anisotropic,\nhemitropic and isotropic materials and also stress function tensors for the\ngauge theory of dislocations."
    },
    {
        "anchor": "Conductivity-Like Gilbert Damping due to Intraband Scattering in\n  Epitaxial Iron: Confirming the origin of Gilbert damping by experiment has remained a\nchallenge for many decades, even for simple ferromagnetic metals. In this\nLetter, we experimentally identify Gilbert damping that increases with\ndecreasing electronic scattering in epitaxial thin films of pure Fe. This\nobservation of conductivity-like damping, which cannot be accounted for by\nclassical eddy current loss, is in excellent quantitative agreement with\ntheoretical predictions of Gilbert damping due to intraband scattering. Our\nresults resolve the longstanding question about a fundamental damping mechanism\nand offer hints for engineering low-loss magnetic metals for cryogenic\nspintronics and quantum devices.",
        "positive": "Steady one-dimensional domain wall motion in biaxial ferromagnets:\n  mapping of the Landau-Lifshitz equation to the sine-Gordon equation: Motivated by the difference between the dynamics of magnetization textures in\nferromagnets and antiferromagnets, the Landau-Lifshitz equation of motion is\nexplored. A typical one-dimensional domain wall in a bulk ferromagnet with\nbiaxial magnetic anisotropy is considered. In the framework of Walker-type of\nsolutions of steady-state ferromagnetic domain wall motion, the reduction of\nthe non-linear Landau-Lifshitz equation to a Lorentz-invariant sine-Gordon\nequation typical for antiferromagnets is formally possible for velocities lower\nthan a critical velocity of the topological soliton. The velocity dependence of\nthe domain wall energy and the domain wall width are expressed in the\nrelativistic-like form in the limit of large ratio of the easy-plane/easy-axis\nanisotropy constants. It is shown that the mapping of the Landau-Lifshitz\nequation of motion to the sine-Gordon equation can be performed only by going\nbeyond the steady-motion Walker-type of solutions."
    },
    {
        "anchor": "Magnetic order and magneto-transport in half-metallic ferrimagnetic\n  Mn$_y$Ru$_x$Ga thin films: The ruthenium content of half-metallic Mn$_2$Ru$_x$Ga thin films, with a\nbiaxially-strained inverse Heusler structure, controls the ferrimagnetism that\ndetermines their magnetic and electronic properties. An extensive study of\nMn$_y$Ru$_x$Ga films on MgO (100) substrates with $1.8 \\leq y \\leq 2.6$ and $x\n= 0.5$, 0.7 or 0.9, including crystallographic, magnetic order,\nmagneto-transport and spin polarisation is undertaken to map specific\ncomposition-dependent properties in this versatile ternary system. A comparison\nof experimental densities obtained from X-ray reflectivity with calculated\ndensities indicates full site occupancy for all compositions, which implies\nchemical disorder. All moments lie on the Slater-Pauling plot with slope 1 and\nall except $x = 0.5$, $y = 2.2$ exhibit magnetic compensation at \\tcmp~below\n500~K. The coercivity near \\tcmp~exceeds 10~T. Increasing the Mn or Ru content\nraises \\tcmp, but increasing Ru also decreases the spin polarisation determined\nby point contact Andreev reflection. Molecular field theory is used to model\nthe temperature dependence of the net ferrimagnetic moment and three principal\nexchange coefficients are deduced. Marked differences in the shape of anomalous\nHall and net magnetisation hysteresis loops are explained by substantial\ncanting of the small net moment by up to \\SI{40}{\\degree} relative to the\n$c$-axis in zero field, which is a result of slight non-collinearity of the\nMn$^{4c}$ sublattice moments due to competing intra-sublattice exchange\ninteractions arising from antisite disorder and excess Mn in the unit cell.\nConsequences are reduced spin polarisation and an enhanced intrinsic\ncontribution to the anomalous Hall effect. The systematic investigation of the\nphysical properties as a function of $x$ and $y$ will guide the selection of\ncompositions to meet the requirements for magnonic and spintronic MRG-based\ndevices.",
        "positive": "Inverse spin Hall effect in a complex ferromagnetic oxide\n  heterostructure: Complex oxide heterostructures are hot candidates for post CMOS\nmulti-functional devices. Especially in spintronics applications ferromagnetic\noxides may play a key role because they can exhibit extraordinary high spin\npolarization. Indeed, there are already plenty of examples in spintronics,\nnotably in the area of spin pumping and inverse spin Hall effect (ISHE)\n\\cite{Azevedo2011, Czeschka2011, Hahn2013, Obstbaum2014}. Although complex\noxides have been used in these experiments as a source of spin currents, they\nhave never been demonstrated to act as a spin sink that exhibits ISHE. Here we\nshow that in a heterostructure consisting of La$_{0.7}$Sr$_{0.3}$MnO$_{3}$\n(LSMO) and SrRuO$_{3}$ (SRO) the low temperature ferromagnet SRO can act as a\nspin sink and exhibit a sizeable ISHE which persists even below its Curie\ntemperature. This result opens up new possibilities for application of all\noxide heterostructures in spintronics and may significantly extend the research\non spin Hall effect and related phenomena."
    },
    {
        "anchor": "Chemical Bonding Analysis on Amphoteric Hydrogen - Alkaline Earth Ammine\n  Borohydrides: Usually the ions in solid are in the positive oxidation states or in the\nnegative oxidation state depending upon the chemical environment. It is highly\nunusual for an ion having both positive as well as negative oxidation state in\na particular compound. Structural analysis suggest that the alkaline earth\nammine borohydrides (AABH) with the chemical formula M (BH4)2(NH3)2 (M = Mg,\nCa, or Sr) where hydrogen is present in +1 and -1 oxidation states. In order to\nunderstand the oxidation states of hydrogen and also the character of chemical\nbond present in AABH we have made charge density, electron localization\nfunction, Born effective charge, Bader effective charge, and density of states\nanalyses using result from the density functional calculations. Our detailed\nanalyses show that hydrogen is in amphoteric behavior with hydrogen closer to\nboron is in negative oxidation state and that closer to nitrogen is in the\npositive oxidation state. Due to the presence of finite covalent bonding\nbetween the consitutents in AABH the oxidation state of hydrogen is\nnon-interger value. The confirmation of the presence of amphtoric behavior of\nhydrogen in AABH has implication in hydrogen storage applications.",
        "positive": "Finding pathways for stoichiometric Co4N thin films: In this work, we studied the pathways for formation of stoichiometric\n\\tcn~thin films. Polycrystalline and epitaxial \\tcn~films were prepared using\nreactive direct current magnetron (dcMS) sputtering technique. A systematic\nvariation in the substrate temperature (\\Ts) during the dcMS process reveals\nthat the lattice parameter (LP) decreases as \\Ts~increases. We found that\nnearly stoichiometric \\tcn~films can be obtained when \\Ts~= 300\\,K. However,\nthey emerge from the transient state of Co target ($\\phi$3\\,inch). By reducing\nthe target size to $\\phi$1\\,inch, now the \\tcn~phase formation takes place from\nthe metallic state of Co target. In this case, LP of \\tcn~film comes out to be\n$\\sim$99\\p~of the value expected for \\tcn. This is the largest value of LP\nfound so far for \\tcn. The pathways achieved for formation of polycrystalline\n\\tcn~were adopted to grow an epitaxial \\tcn~film, which shows four fold\nmagnetic anisotropy in magneto-optic Kerr effect measurements. Detailed\ncharacterization using secondary ion mass spectroscopy indicates that N\ndiffuses out when \\Ts~is raised even to 400\\,K. Measurement of electronic\nstructure using x-ray photoelectron spectroscopy and x-ray absorption\nspectroscopy further confirms it. Magnetization measurements using bulk\nmagnetization and polarized neutron reflectivity show that the saturation\nmagnetization of stoichiometric \\tcn~film is even larger than pure Co. Since\nall our measurements indicated that N could be diffusing out, when \\tcn~films\nare grown at high \\Ts, we did actual N self-diffusion measurements in a CoN\nsample and found that N self-diffusion was indeed substantially higher. The\noutcome of this work clearly shows that the \\tcn~films grown prior to this work\nwere always N deficient and the pathways for formation of a stoichiometric\n\\tcn~have been achieved."
    },
    {
        "anchor": "\u00c5ngstr\u00f6m-resolved Interfacial Structure in Organic-Inorganic\n  Junctions: Charge transport processes at interfaces which are governed by complex\ninterfacial electronic structure play a crucial role in catalytic reactions,\nenergy storage, photovoltaics, and many biological processes. Here, the first\nsoft X-ray second harmonic generation (SXR-SHG) interfacial spectrum of a\nburied interface (boron/Parylene-N) is reported. SXR-SHG shows distinct\nspectral features that are not observed in X-ray absorption spectra,\ndemonstrating its extraordinary interfacial sensitivity. Comparison to\nelectronic structure calculations indicates a boron-organic separation distance\nof 1.9 {\\AA}, wherein changes as small as 0.1 {\\AA} result in easily detectable\nSXR-SHG spectral shifts (ca. 100s of meV). As SXR-SHG is inherently ultrafast\nand sensitive to individual atomic layers, it creates the possibility to study\na variety of interfacial processes, e.g. catalysis, with ultrafast time\nresolution and bond specificity.",
        "positive": "Machine learning, phase stability, and disorder with the Automatic Flow\n  Framework for Materials Discovery: Traditional materials discovery approaches - relying primarily on laborious\nexperiments - have controlled the pace of technology. Instead, computational\napproaches offer an accelerated path: high-throughput exploration and\ncharacterization of virtual structures. These ventures, performed by automated\nab-initio frameworks, have rapidly expanded the volume of\nprogrammatically-accessible data, cultivating opportunities for data-driven\napproaches. Herein, a collection of robust characterization methods are\npresented, implemented within the Automatic Flow Framework for Materials\nDiscovery (AFLOW), that leverages materials data for the prediction of phase\ndiagrams and properties of disordered materials. These methods directly address\nthe issue of materials synthesizability, bridging the gap between simulation\nand experiment. Powering these predictions is the AFLOW.org repository for\ninorganic crystals, the largest and most comprehensive database of its kind,\ncontaining more than 2 million compounds with about 100 different properties\ncomputed for each. As calculated with standardized parameter sets, the wealth\nof data also presents a favorable learning environment. Machine learning\nalgorithms are employed for property prediction, descriptor development, design\nrule discovery, and the identification of candidate functional materials. When\ncombined with physical models and intelligently formulated descriptors, the\ndata becomes a powerful tool, facilitating the discovery of new materials for\napplications ranging from high-temperature superconductors to thermoelectrics.\nThese methods have been validated by the synthesis of two new permanent magnets\nintroduced herein - the first discovered by computational approaches."
    },
    {
        "anchor": "Universal rules for visible-light absorption in hybrid perovskite\n  materials: A variety of organic-inorganic hybrid perovskites (APbX3) consisting of mixed\ncenter cations [A = CH3NH3+, HC(NH2)2+, Cs+] with different PbX3- cages (X = I,\nBr, Cl) have been developed to realize high-efficiency solar cells.\nNevertheless, clear understanding for the effects of A and X on the optical\ntransition has been lacking. Here, we present universal rules that allow the\nunified interpretation of the optical absorption in various hybrid perovskites.\nIn particular, we find that the influence of the A-site cation on the light\nabsorption is rather significant and the absorption coefficient (alpha) reduces\nto half when CH3NH3+ is replaced with HC(NH2)2+ in the APbI3 system. Our\ndensity functional theory (DFT) calculations reproduce all of the fine\nabsorption features observed in HC(NH2)2PbI3 and CH3NH3PbBr3, allowing the\nunique assignment of the interband transitions in the Brillouin zone. In\ncontrast to general understanding that the A-site cation involves weakly in the\noptical process, our theoretical calculations reveal that the center cation\nplays a critical role in the interband transition and the absorption strength\nin the visible region is modified by the strong A-X interaction. Furthermore,\nour systematic analyses show that the variation of the absorption spectrum with\nX can be described simply by the well-known sum rule. The universal rules\nestablished in this study explain the large reduction of alpha in HC(NH2)2PbI3\nand predict CsPbI3 as the highest alpha material.",
        "positive": "Defect-mediated relaxation and non-linear susceptibilities of Rochelle\n  salt: The deformable pseudospin Mitsui model is modified in order to take into\naccount interactions of the ordering dipoles of Rochelle salt with dipoles,\nassociated with switchable crystal defects. Using the Glauber-type kinetics of\nthe ordering and defect pseudospins, we calculate the linear, second, and third\norder dynamic susceptibilities and piezoelectric coefficients of the system.\nThe defect-assisted dispersion of the dynamic characteristics below 1 kHz is\ndescribed. Behavior of the linear and non-linear susceptibilities close to\nT_C1,2 is also satisfactorily described by the presented model."
    },
    {
        "anchor": "How square ice helps lubrication: In the context of friction we use atomistic molecular-dynamics simulations to\ninvestigate water confined between graphene sheets over a wide range of\npressures. We find that thermal equilibration of the confined water is hindered\nat high pressures. We demonstrate that, under the right conditions, square ice\ncan form in an asperity, and that it is similar to cubic ice VII and ice X. We\nsimulate sliding of atomically flat graphite on the square ice and find\nextremely low friction due to structural superlubricity. The conditions needed\nfor square ice to form correspond to low sliding speeds, and we suggest that\nthe ice observed in experiments of friction on wet graphite is of this type.",
        "positive": "Extended Kohler$^,$s Rule of Magnetoresistance: A notable phenomenon in topological semimetals is the violation of\nKohler$^,$s rule, which dictates that the magnetoresistance $MR$ obeys a\nscaling behavior of $MR = f(H/\\rho_0$), where $MR = [\\rho_H-\\rho_0]/\\rho_0$ and\n$H$ is the magnetic field, with $\\rho_H$ and $\\rho_0$ being the resistivity at\n$H$ and zero field, respectively. Here we report a violation originating from\nthermally-induced change in the carrier density. We find that the\nmagnetoresistance of the Weyl semimetal, TaP, follows an extended Kohler$^,$s\nrule $MR = f[H/(n_T\\rho_0)]$, with $n_T$ describing the temperature dependence\nof the carrier density. We show that $n_T$ is associated with the Fermi level\nand the dispersion relation of the semimetal, providing a new way to reveal\ninformation on the electronic bandstructure. We offer a fundamental\nunderstanding of the violation and validity of Kohler$^,$s rule in terms of\ndifferent temperature-responses of $n_T$. We apply our extended Kohler$^,$s\nrule to BaFe$_2$(As$_{1-x}$P$_x$)$_2$ to settle a long-standing debate on the\nscaling behavior of the normal-state magnetoresistance of a superconductor,\nnamely, $MR$ ~ $tan^2\\theta_H$, where $\\theta_H$ is the Hall angle. We further\nvalidate the extended Kohler$^,$s rule and demonstrate its generality in a\nsemiconductor, InSb, where the temperature-dependent carrier density can be\nreliably determined both theoretically and experimentally."
    },
    {
        "anchor": "Ferromagnetic Resonance in Permalloy Metasurfaces: Permalloy films with one-dimensional (1D) profile modulation of submicron\nperiodicity are fabricated based on commercially available DVD-R discs and\nstudied using ferromagnetic resonance (FMR) method and micromagnetic numerical\nsimulations. The main resonance position shows in-plane angular dependence\nwhich is strongly reminiscent of that in ferromagnetic films with uniaxial\nmagnetic anisotropy. The main signal and additional low field lines are\nattributed to multiple standing spin wave resonances defined by the grating\nperiod. The results may present interest in magnetic metamaterials and\nmagnonics applications.",
        "positive": "Crystal Chemistry and Magnetic Properties of Manganese Zinc Alloy\n  \"YMn2Zn20\" Comprising a Mn Pyrochlore Lattice: The chemical composition, crystal structure, and magnetic properties of a\nmanganese zinc alloy with an ideal composition of YMn2Zn20, which comprises a\npyrochlore lattice made of Mn atoms, are reported. The compound is stable only\nwhen In or Al is partially substituted for Zn. We have determined the actual\nchemical formula as YMn2+dZn20-x-dMx, with M = In or Al, and have identified\nthe characteristic preferences with which the incorporated M and excess Mn\natoms occupy the three crystallographic sites for Zn atoms. The Mn atoms in the\npyrochlore lattice possess small magnetic moments that interact with each other\nantiferromagnetically but exhibit no long-range order above 0.4 K, probably\nowing to the geometrical frustration of the pyrochlore lattice. As a result,\nthe effective mass of the conduction electrons is considerably enhanced, as\nobserved in the related pyrochlore-lattice compounds (Y,Sc)Mn2 and LiV2O4.\nHowever, the presence of excess Mn atoms with large localized magnetic moments\ncomparable to spin 5/2 tends to mask the inherent magnetism of the pyrochlore\nMn atoms. It is suggested that \"YMn2Zn18In2\" with neither excess Mn atoms nor\nsite disorder would be an ideal compound for further study."
    },
    {
        "anchor": "Monitoring surface resonances on Co2MnSi(100) by spin-resolved\n  photoelectron spectroscopy: The magnitude of the spin polarization at the Fermi level of ferromagnetic\nmaterials at room temperature is a key property for spintronics. Investigating\nthe Heusler compound Co$_2$MnSi a value of 93$\\%$ for the spin polarization has\nbeen observed at room temperature, where the high spin polarization is related\nto a stable surface resonance in the majority band extending deep into the\nbulk. In particular, we identified in our spectroscopical analysis that this\nsurface resonance is embedded in the bulk continuum with a strong coupling to\nthe majority bulk states. The resonance behaves very bulk-like, as it extends\nover the first six atomic layers of the corresponding (001)-surface. Our study\nincludes experimental investigations, where the bulk electronic structure as\nwell as surface-related features have been investigated using spin-resolved\nphotoelectron spectroscopy (SR-UPS) and for a larger probing depth\nspin-integrated high energy x-ray photoemission spectroscopy (HAXPES). The\nresults are interpreted in comparison with first-principles band structure and\nphotoemission calculations which consider all relativistic, surface and\nhigh-energy effects properly.",
        "positive": "Bridging Theory with Experiment: Digital Twins and Deep Learning\n  Segmentation of Defects in Monolayer MX2 Phases: Developing methods to understand and control defect formation in\nnanomaterials offers a promising route for materials discovery. Monolayer MX2\nphases represent a particularly compelling case for defect engineering of\nnanomaterials due to the large variability in their physical properties as\ndifferent defects are introduced into their structure. However, effective\nidentification and quantification of defects remains a challenge even as\nhigh-throughput scanning tunneling electron microscopy (STEM) methods improve.\nThis study highlights the benefits of employing first principles calculations\nto produce digital twins for training deep learning segmentation models for\ndefect identification in monolayer MX2 phases. Around 600 defect structures\nwere obtained using density functional theory calculations, with each monolayer\nMX2 structure being subjected to multislice simulations for the purpose of\ngenerating the digital twins. Several deep learning segmentation architectures\nwere trained on this dataset, and their performances evaluated under a variety\nof conditions such as recognizing defects in the presence of unidentified\nimpurities, beam damage, grain boundaries, and with reduced image quality from\nlow electron doses. This digital twin approach allows benchmarking different\ndeep learning architectures on a theory dataset, which enables the study of\ndefect classification under a broad array of finely controlled conditions. It\nthus opens the door to resolving the underpinning physical reasons for model\nshortcomings, and potentially chart paths forward for automated discovery of\nmaterials defect phases in experiments."
    },
    {
        "anchor": "A facile process for soak-and-peel delamination of CVD graphene from\n  substrates using water: We demonstrate a simple technique to transfer CVD-grown graphene from copper\nand platinum substrates using a soak-and-peel delamination technique utilizing\nonly hot deionized water. The lack of chemical etchants results in cleaner CVD\ngraphene films minimizing unintentional doping, as confirmed by Raman and\nelectrical measurements. The process allows the reuse of substrates and hence\ncan enable the use of oriented substrates for growth of higher quality\ngraphene, and is an inherently inexpensive and scalable process for large-area\nproduction.",
        "positive": "Deep sub-\u00c5ngstrom imaging of 2D materials with a high dynamic range\n  detector: Aberration-corrected optics have made electron microscopy at\natomic-resolution a widespread and often essential tool for\nnanocharacterization. Image resolution is dominated by beam energy and the\nnumerical aperture of the lens ({\\alpha}), with state-of-the-art reaching ~0.47\n{\\AA} at 300 keV. Two-dimensional materials are imaged at lower beam energies\nto avoid knock-on damage, limiting spatial resolution to ~1 {\\AA}. Here, by\ncombining a new electron microscope pixel array detector with the dynamic range\nto record the complete distribution of transmitted electrons and full-field\nptychography to recover phase information from the full phase space, we\nincreased the spatial resolution well beyond the traditional lens limitations.\nAt 80 keV beam energy, our ptychographic reconstructions significantly improved\nimage contrast of single-atom defects in MoS2, reaching an information limit\nclose to 5{\\alpha}, corresponding to a 0.39 {\\AA} Abbe resolution, at the same\ndose and imaging conditions where conventional imaging modes reach only 0.98\n{\\AA}."
    },
    {
        "anchor": "Influence of the growth conditions on the magnetism of\n  SrFe$_{12}$O$_{19}$ thin films and the behavior of Co / SrFe$_{12}$O$_{19}$\n  bilayers: SrFe$_{12}$O$_{19}$ (SFO) films grown on Si (100) substrates by\nradio-frequency magnetron sputtering have been characterized in terms of\ncomposition, structural and magnetic properties by a combination of microscopy,\ndiffraction and spectroscopy techniques. M\\\"ossbauer spectroscopy was used to\ndetermine the orientation of the films magnetization, which was found to be\ncontrolled by both the sputtering power and the thickness of the films.\nAdditionally, the coupling between the SFO films and a deposited cobalt\noverlayer was studied by means of synchrotron-based spectromicroscopy\ntechniques. A structural coupling at the SFO/Co interface is suggested to\naccount for the expetimental observations. Micromagnetic simulations were\nperformed in order to reproduce the experimental behaviour of the system.",
        "positive": "Novel Observation of Piezoelectricity in VO2: VO2 is well known for its dual phase transitions; electrical as well as\nstructural, at a single temperature of 340K. The low temperature structural\nphases of VO2 are different from its high temperature counterpart by means of\nstructural symmetry. The strain induced modification of the structural\ndistortion in VO2 is studied in details. A ferroelectric type distortion is\nobserved, and therefore, the piezoelectric effect in the low temperature phases\nof VO2 is investigated, for the first time, using piezo-response force\nmicroscopy. The electronic behavior of piezoelectric materials can be tuned\nwith the application of mechanical strain and strain is the only factor to\nseparate the two low-temperature phases, namely, M1 and M2 in the phase diagram\nof VO2. The piezo-electric coefficient in the strained phase of VO2 was found\nas 11-12 pm/V making it eligible for piezotronic applications."
    },
    {
        "anchor": "Irida-Graphene: A New 2D Carbon Allotrope: Several 2D carbon-based materials have been computationally designed in the\nlast years due to the success achieved by graphene. Here, we propose a new 2D\nall-sp$^2$ carbon allotrope, named Irida-Graphene (IG), using a bottom-up\napproach. IG is composed of fused rings containing 3-6-8 carbon atoms. We\nemployed density functional theory calculations and reactive (ReaxFF) molecular\ndynamics simulations to examine its mechanical, structural, electronic, and\noptical properties. Results showed that IG exhibits good dynamical and thermal\nstabilities. Its estimated elastic modulus varies between 80-113 GPa. IG is a\nmetallic material and presents a Dirac cone above the Fermi level in the center\nof the band. The intense optical activity of IG is restricted to the infrared\nand violet regions. IG can act as a violet collector for photon energies of\nabout 3.0 eV since it presents very low reflectivity and refractive index\ngreater than one.",
        "positive": "The Dynamics of Magnetism in Fe-Cr Alloys with Cr Clustering: The dynamics of magnetic moments in iron-chromium alloys with different\nlevels of Cr clustering show unusual features resulting from the fact that even\nin a perfect body-centred cubic structure, magnetic moments experience\ngeometric magnetic frustration resembling that of a spin glass. Due to the long\nrange exchange coupling and configuration randomness, magnetic moments of Cr\nsolutes remain non-collinear at all temperatures. To characterise magnetic\nproperties of Fe-Cr alloys, we explore the temperature dependence of\nmagnetisation, susceptibility, Curie temperature and spin-spin correlations\nwith spatial resolution. The static and dynamic magnetic properties are\ncorrelated with the microstructure of Fe-Cr, where magnetisation and\nsusceptibility are determined by the size of Cr precipitates at nominal Cr\nconcentrations. The Curie temperature is always maximised when the solute\nconcentration of Cr in the $\\alpha$ phase is close to 5 to 6 at.\\%, and the\nsusceptibility of Fe atoms is always enhanced at the boundary between a\nprecipitate and solid solution. Interaction between Cr and Fe stimulates\nmagnetic disorder, lowering the effective Curie temperature. Dynamic simulation\nof evolution of magnetic correlations shows that the spin-spin relaxation time\nin Fe-Cr alloys is in the 20 to 40 ps range."
    },
    {
        "anchor": "Spin-dependent tunneling and Coulomb blockade in ferromagnetic\n  nanoparticles: We review studies on spin-dependent tunneling phenomena in systems containing\nferromagnetic nanoparticles. We discuss preparation methods of assembling\nnanoparticles as well as the mechanisms and results of spin-dependent transport\nproperties. The emphasis of this review is on characteristic spin-dependent\ntunneling phenomena such as enhanced tunnel magnetoresistance (TMR) due to\nco-tunneling in the Coulomb blockade regime and sign changes of the TMR due to\nspin accumulation in nanoparticles.",
        "positive": "Ab initio optimization of phonon drag effect for lower-temperature\n  thermoelectric energy conversion: While the thermoelectric figure of merit zT above 300K has seen significant\nimprovement recently, the progress at lower temperatures has been slow, mainly\nlimited by the relatively low Seebeck coefficient and high thermal\nconductivity. Here we report, for the first time, success in first-principles\ncomputation of the phonon drag effect - a coupling phenomenon between electrons\nand non-equilibrium phonons - in heavily doped region and its optimization to\nenhance the Seebeck coefficient while reducing the phonon thermal conductivity\nby nanostructuring. Our simulation quantitatively identifies the major phonons\ncontributing to the phonon drag, which are spectrally distinct from those\ncarrying heat, and further reveals that while the phonon drag is reduced in\nheavily-doped samples, a significant contribution to Seebeck coefficient still\nexists. An ideal phonon filter is proposed to enhance zT of silicon at room\ntemperature by a factor of 20 to around 0.25, and the enhancement can reach 70\ntimes at 100K. This work opens up a new venue towards better thermoelectrics by\nharnessing non-equilibrium phonons."
    },
    {
        "anchor": "Properties of the water to boron nitride interaction: from zero to two\n  dimensions with benchmark accuracy: Molecular adsorption on surfaces plays an important part in catalysis,\ncorrosion, desalination, and various other processes that are relevant to\nindustry and in nature. As a complement to experiments, accurate adsorption\nenergies can be obtained using various sophisticated electronic structure\nmethods that can now be applied to periodic systems. The adsorption energy of\nwater on boron nitride substrates, going from zero to 2-dimensional\nperiodicity, is particularly interesting as it calls for an accurate treatment\nof polarizable electrostatics and dispersion interactions, as well as posing a\npractical challenge to experiments and electronic structure methods. Here, we\npresent reference adsorption energies, static polarizabilities, and dynamic\npolarizabilities, for water on BN substrates of varying size and dimension.\nAdsorption energies are computed with coupled cluster theory, fixed-node\nquantum Monte Carlo (FNQMC), the random phase approximation (RPA), and second\norder M{\\o}ller-Plesset (MP2) theory. These explicitly correlated methods are\nfound to agree in molecular as well as periodic systems. The best estimate of\nthe water/h-BN adsorption energy is $-107\\pm7$ meV from FNQMC. In addition, the\nwater adsorption energy on the BN substrates could be expected to grow\nmonotonically with the size of the substrate due to increased dispersion\ninteractions but interestingly, this is not the case here. This peculiar\nfinding is explained using the static polarizabilities and molecular dispersion\ncoefficients of the systems, as computed from time-dependent density functional\ntheory (DFT). Dynamic as well as static polarizabilities are found to be highly\nanisotropic in these systems. In addition, the many-body dispersion method in\nDFT emerges as a particularly useful estimation of finite size effects for\nother expensive, many-body wavefunction based methods.",
        "positive": "The synergistic modulation of electronic and geometry structures leads\n  to ultra-low thermal conductivity of graphene-like borides (g-B3X5, X=N, P,\n  As): The design of novel devices with specific technical interests through\nmodulating structural properties and bonding characteristics promotes the\nvigorous development of materials informatics. Herein, we propose a synergy\nstrategy of component reconstruction by combining geometric configuration and\nbonding characteristics. With the synergy strategy, we designed a novel\ntwo-dimensional (2D) graphene-like borides, e.g. g-B3N5, which possesses\ncounter-intuitive ultra-low thermal conductivity of 21.08 W/mK despite the\nsmall atomic mass. The ultra-low thermal conductivity is attributed to the\nsynergy effect of electronics and geometry on thermal transport due to the\ncombining reconstruction of g-BN and nitrogene. With the synergy effect, the\ndominant acoustic branches are strongly softened, and the scattering absorption\nand Umklapp process are simultaneously suppressed. Thus, the thermal\nconductivity is significantly lowered. To verify the component reconstruction\nstrategy, we further constructed g-B3P5 and g-B3As5, and uncovered the\nultra-low thermal conductivity of 2.50 and 1.85 W/mK, respectively. The synergy\neffect and the designed ultra-low thermal conductivity materials with\nlightweight atomic mass cater to the demand for light development of momentum\nmachinery and heat protection, such as aerospace vehicles, high-speed rail,\nautomobiles."
    },
    {
        "anchor": "Estimating melting curves for Cu and Al from simulations at a single\n  state point: Determining the melting curves of materials up to high pressures has long\nbeen a challenge experimentally and theoretically. A large class of materials,\nincluding most metals, has been shown to exhibit hidden scale invariance, an\napproximate scale invariance of the potential-energy landscape that is not\nobvious from the Hamiltonian. For these materials the isomorph theory allows\nthe identification of curves in the phase diagram along which structural and\ndynamical properties are invariant to a good approximation when expressed in\nappropriately scaled form. These curves, the isomorphs, can also be used as the\nbasis for constructing accurate melting curves from simulations at a single\nstate point [U. R. Pedersen et al., Nat. Comm. 7, 12386 (2016)]. In this work\nwe apply this method to the metals Cu simulated using the effective medium\ntheory and Al simulated using density functional theory (DFT). For Cu the\nmethod works very well and is validated using two-phase melting point\nsimulations. For Al there are likewise good isomorphs, and the method generates\nthe melting curve accurately as compared to previous experimental and DFT\nresults. In support of a recent suggestion of Hong and van de Walle [Phys. Rev.\nB 100, 140102 (2019)], we finally suggest that the tendency for the\ndensity-scaling exponent $\\gamma$ to decrease with increasing density in metals\nimplies that metals in general will undergo re-entrant melting, i.e., have a\nmaximum of melting temperature as a function of pressure.",
        "positive": "Computational and experimental imaging of Mn defects on GaAs (110)\n  cross-sectional surface: We present a combined experimental and computational study of the (110)\ncross-sectional surface of Mn $\\delta$-doped GaAs samples. We focus our study\non three different selected Mn defect configurations not previously studied in\ndetails, namely surface interstitial Mn, isolated and in pairs, and\nsubstitutional Mn atoms on cationic sites (Mn$_{\\rm Ga}$) in the first\nsubsurface layer. The sensitivity of the STM images to the specific local\nenvironment allows to distinguish between Mn interstitials with nearest\nneighbor As atoms (Int$_{\\rm As}$) rather than Ga atoms (Int$_{\\rm Ga}$), and\nto identify the fingerprint of peculiar satellite features around subsurface\nsubstitutional Mn. The simulated STM maps for Int$_{\\rm As}$, both isolated and\nin pairs, and Mn$_{\\rm Ga}$ in the first subsurface layer are consistent with\nsome experimental images hitherto not fully characterized."
    },
    {
        "anchor": "Raman tensor elements of $\u03b2\\text{-Ga}_2\\text{O}_3$: The Raman spectrum and particularly the Raman scattering intensities of\nmonoclinic $\\beta\\text{-Ga}_2\\text{O}_3$ are investigated by experiment and\ntheory. The low symmetry of $\\beta\\text{-Ga}_2\\text{O}_3$ results in a complex\ndependence of the Raman intensity for the individual phonon modes on the\nscattering geometry which is additionally affected by birefringence. We\nmeasured the Raman spectra in dependence on the polarization direction for\nbackscattering on three crystallographic planes of\n$\\beta\\text{-Ga}_2\\text{O}_3$ and modeled these dependencies using a modified\nRaman tensor formalism which takes birefringence into account. The spectral\nposition of all 15 Raman-active phonon modes and the Raman tensor elements of\n13 modes were determined and are compared to results from ab-initio\ncalculations.",
        "positive": "Pseudo-Fermi surface and phonon softening in sodium with a stepwise\n  electron distribution: The absorption of light by a metal disturbs the electron distribution around\nthe Fermi surface. Here, we calculate the phonon dispersion relations of\nfree-electron-like metal, bcc sodium, with a stepwise electron distribution\nfunction by using a model pseudo-potential method. The step can behave as a\npseudo-Fermi surface, which produces the singularities at specific wavenumbers\nin the response function. The singularity gives rise to long-range oscillations\nin the interatomic potential and results in imaginary phonon frequencies around\nthe N point."
    },
    {
        "anchor": "Estimation of gloss from rough surface parameters: Gloss is a quantity used in the optical industry to quantify and categorize\nmaterials according to how well they scatter light specularly. With the aid of\nphase perturbation theory, we derive an approximate expression for this\nquantity for a one-dimensional randomly rough surface. It is demonstrated that\ngloss depends in an exponential way on two dimensionless quantities that are\nassociated with the surface randomness: the root-mean-square roughness times\nthe perpendicular momentum transfer for the specular direction, and a\ncorrelation function dependent factor times a lateral momentum variable\nassociated with the collection angle. Rigorous Monte Carlo simulations are used\nto access the quality of this approximation, and good agreement is observed\nover large regions of parameter space.",
        "positive": "First-principles calculation of spin-orbit torque in a Co/Pt bilayer: The angular dependence of spin-orbit torque in a disordered Co/Pt bilayer is\ncalculated using a first-principles non-equilibrium Green's function formalism\nwith an explicit supercell averaging over Anderson disorder. In addition to the\nusual dampinglike and fieldlike terms, the odd torque contains a sizeable\nplanar Hall-like term $(\\mathbf{m\\cdot\nE})\\mathbf{m}\\times(\\mathbf{z}\\times\\mathbf{m})$ whose contribution to\ncurrent-induced damping is consistent with experimental observations. The\ndampinglike and planar Hall-like torquances depend weakly on disorder strength,\nwhile the fieldlike torquance declines with increasing disorder. The torques\nthat contribute to damping are almost entirely due to spin-orbit coupling on\nthe Pt atoms, but the fieldlike torque does not require it."
    },
    {
        "anchor": "Interface-dominated plasticity and kink bands in metallic nanolaminates: The theoretical and computational framework of finite deformation mesoscale\nfield dislocation mechanics (MFDM) is used to understand the salient aspects of\nkink-band formation in Cu-Nb nano-metallic laminates (NMLs). A conceptually\nminimal, plane-strain idealization of the three-dimensional geometry, including\ncrystalline orientation, of additively manufactured NML is used to model NMLs.\nImportantly, the natural jump/interface condition of MFDM imposing continuity\nof (certain components) of plastic strain rates across interfaces allows\ntheory-driven `communication' of plastic flow across the laminate boundaries in\nour finite element implementation. Kink bands under layer parallel compression\nof NMLs in accord with experimental observations arise in our numerical\nsimulations. The possible mechanisms for the formation and orientation of kink\nbands are discussed, within the scope of our idealized framework. We also\nreport results corresponding to various parametric studies that provide\npreliminary insights and clear questions for future work on understanding the\nintricate underlying mechanisms for the formation of kink bands.",
        "positive": "On the study of local stress rearrangements during quasistatic plastic\n  shear of a model glass: do local stress components contain enough\n  information?: We present a numerical study of the mechanical response of a 2D Lennard-Jones\namorphous solid under steady quasistatic and athermal shear. We focus here on\nthe evolution of local stress components. While the local stress is usually\ntaken as an order parameter in the description of the rheological behaviour of\ncomplex fluids, and for plasticity in glasses, we show here that the knowledge\nof local stresses is not sufficient for a complete description of the plastic\nbehaviour of our system. The distribution of local stresses can be\napproximately described as resulting from the sum of localized quadrupolar\nevents with an exponential distribution of amplitudes. However, we show that\nthe position of the center of the quadrupoles is not related to any special\nevolution of the local stress, but must be described by another variable."
    },
    {
        "anchor": "A microscopic continuum model for defect dynamics in metallic glasses: Motivated by results of the topological theory of glasses accounting for\ngeometric frustration, we develop the simplest possible continuum mechanical\nmodel of defect dynamics in metallic glasses that accounts for topological,\nenergetic, and kinetic ideas. The model is aimed towards the development of a\nmicroscopic understanding of the plasticity of such materials. We discuss the\nexpected predictive capabilities of the model vis-a-vis some observed physical\nbehaviors of metallic glasses.",
        "positive": "Surface structure of Bi2Se3(111) determined by low-energy electron\n  diffraction and surface X-ray diffraction: The surface structure of the prototypical topological insulator Bi2Se3 is\ndetermined by low-energy electron diffraction and surface X-ray diffraction at\nroom temperature. Both approaches show that the crystal is terminated by an\nintact quintuple layer. Specifically, an alternative termination by a bismuth\nbilayer is ruled out. Surface relaxations obtained by both techniques are in\ngood agreement with each other and found to be small. This includes the\nrelaxation of the van der Waals gap between the first two quintuple layers."
    },
    {
        "anchor": "Rational Doping Strategy of Porous Materials for Hydrogen Storage: CNTs\n  study case: Identifying a nanostructure suitable for hydrogen storage presents a\npromising avenue for the secure and cost-effective utilization of hydrogen as a\ngreen energy source. This study introduces a systematic approach for selecting\noptimal doping on porous materials, emphasizing the intricate interplay between\ndoping with the material's structure and the interaction between doping and\nhydrogen. Our proposed approach serves as a framework for evaluating and\npredicting the performance of doped materials. To validate the efficacy of our\nstrategy, we conduct a comprehensive investigation in carbon nanotubes (CNTs).\nApplying our criteria, we systematically screen several dopants in CNTs. The\nresults highlight Cu-doped CNTs as promising candidates for hydrogen storage\napplications. Focusing on Cu-doped CNTs, we analyze binding energy, charge\ntransfer, partial density of states (PDOS), and desorption temperature to\nassess the performance of modified CNTs. Additionally, we explore the\nfeasibility of doped CNTs featuring various sizes of copper clusters and the\neffect on the release temperature, i.e., complete regeneration. The findings\nindicate that incorporating 5 to 6% copper impurity onto CNT surfaces renders\nthese nanostructures highly applicable for reversible hydrogen storage near\nambient conditions.",
        "positive": "Building clusters atom by atom: from local order to global order: We have carried out extensive density functional calculations for series of\nsodium clusters $Na$$_{N}$ ranging from $N$=10 to 147 and have obtained\n$\\approx$ 13000 distinct isomers. We unravel a number of striking features of\nthe growth characteristics. The growth shows order-disorder-order pattern of\ncyclic nature. Between two ordered clusters the growth proceeds via disordered\nclusters having multi-centered icosahedral local order. The Global order\nemerges suddenly with the addition of one or two atoms only. The clusters\naround $N$=92, the electronically closed shell system, behave completely\ndifferently and do not show the favored icosahedral local order. It is the\nabsence of icosahedral local order which is responsible for rather low melting\ntemperatures observed in the experiments."
    },
    {
        "anchor": "On the nature of the (de)coupling of the magnetostructural transition in\n  Er$_5$Si$_4$: In this report, a successful thermodynamical model was employed to understand\nthe structural transition in Er$_5$Si$_4$, able to explain the decoupling of\nthe magnetic and structural transition. This was achieved by the DFT\ncalculations which were used to determine the energy differences at 0 K, using\na LSDA+U approximation. It was found that the M structure as the stable phase\nat low temperatures as verified experimentally with a $\\Delta F_0 = -$0.262 eV.\nFinally, it was achieved a variation of Seebeck coefficient ($\\sim$ 6 $\\mu$V)\nat the structural transition which allow to conclude that the electronic\nentropy variation is negligible in the transition.",
        "positive": "Finite-size corrections for defect-involving vertical transitions in\n  supercell calculations: A correction method for vertical transition levels (VTLs) involving defect\nstates calculated with a supercell technique is formulated and its\neffectiveness is systematically verified with ten defects in prototypical\nmaterials: cubic-BN, GaN, MgO, and 3C-SiC. Without any corrections, the\nabsolute errors are around 1 eV with moderate size supercells in most cases. In\ncontrast, when our correction method is adopted, the absolute errors are\nreduced and become less than 0.12 eV in all the cases. Our correction scheme is\ngeneral and will have the potential for wide application as it is adaptive for\nevaluating various quantities at fixed geometry, as represented by those\nrelevant to the generalized Koopmans' theorem."
    },
    {
        "anchor": "Electronic structure, optical and magnetic properties of Co$_{2}$FeGe\n  Heusler alloy films: Optical properties of ferromagnetic half-metallic full-Heusler Co$_{2}$FeGe\nalloy are investigated experimentally and theoretically. Co$_{2}$FeGe thin\nfilms were obtained by DC magnetron sputtering and show the saturation\nmagnetization at $T$=10 K of $m\\approx$5.6 $\\mu_{B}$/f.u., close to the value\npredicted by the Slater-Pauling rule. First-principles calculations of the\nelectronic structure and the dielectric tensor are performed using the\nfull-potential linearized-augmented-plane-wave method in the generalized\ngradient (GGA) and GGA+U approximations. The measured interband optical\nconductivity spectrum for the alloy exhibits a strong absorption band in the 1\n- 4 eV energy range with pronounced fine structure, which agrees well with the\ncalculated half-metallic spectrum of the system, suggesting a near perfect\nspin-polarization in the material.",
        "positive": "Magnetic State Control of Non-van der Waals 2D Materials by\n  Hydrogenation: Controlling the magnetic state of two-dimensional (2D) materials is crucial\nfor spintronic applications. By employing data-mining and autonomous density\nfunctional theory calculations, we demonstrate the switching of magnetic\nproperties of 2D non-van der Waals materials upon hydrogen passivation. The\nmagnetic configurations are tuned to states with flipped and enhanced moments.\nFor 2D CdTiO$_3$ - a nonmagnetic compound in the pristine case - we observe an\nonset of ferromagnetism upon hydrogenation. Further investigation of the\nmagnetization density of the pristine and passivated systems provides a\ndetailed analysis of modified local spin symmetries and the emergence of\nferromagnetism. Our results indicate that selective surface passivation is a\npowerful tool for tailoring magnetic properties of nanomaterials such as\nnon-vdW 2D compounds."
    },
    {
        "anchor": "Colossal linear magnetoelectricity in polar magnet Fe2Mo3O8: Linear magnetoelectric effect is an attractive phenomenon in condensed\nmatters and provides indispensable technological functionalities. Here a\ncolossal linear magnetoelectric effect with diagonal component alfa_33 reaching\nup to ~480 ps/m is reported in a polar magnet Fe2Mo3O8, and this effect can\npersist in a broad range of magnetic field (~20 T) and is orders of magnitude\nlarger than reported values in literature. Such an exceptional experimental\nobservation can be well reproduced by a theoretical model affirmatively\nunveiling the vital contributions from the exchange striction, while the sign\ndifference of magnetocrystalline anisotropy can also be reasonably figured out.",
        "positive": "Density-functional embedding using a plane-wave basis: The constrained electron density method of embedding a Kohn-Sham system in a\nsubstrate system (first described by P. Cortona, Phys. Rev. B {\\bf 44}, 8454\n(1991) and T.A. Wesolowski and A. Warshel, J. Phys. Chem {\\bf 97}, 8050 (1993))\nis applied with a plane-wave basis and both local and non-local\npseudopotentials. This method divides the electron density of the system into\nsubstrate and embedded electron densities, the sum of which is the electron\ndensity of the system of interest. Coupling between the substrate and embedded\nsystems is achieved via approximate kinetic energy functionals. Bulk aluminium\nis examined as a test case for which there is a strong interaction between the\nsubstrate and embedded systems. A number of approximations to the\nkinetic-energy functional, both semi-local and non-local, are investigated. It\nis found that Kohn-Sham results can be well reproduced using a non-local\nkinetic energy functional, with the total energy accurate to better than 0.1 eV\nper atom and good agreement between the electron densities."
    },
    {
        "anchor": "Grain boundaries in ultrafine grained materials processed by severe\n  plastic deformation and related phenomena: Grain boundaries in ultrafine grained (UFG) materials processed by severe\nplastic deformation (SPD) are often called \"non-equilibrium\" grain boundaries.\nSuch boundaries are characterized by excess grain boundary energy, presence of\nlong range elastic stresses and enhanced free volumes. These features and\nrelated phenomena (diffusion, segregation, etc.) have been the object of\nintense studies and the obtained results provide convincing evidence of the\nimportance of a non-equilibrium state of high angle grain boundaries for UFG\nmaterials with unusual properties. The aims of the present paper are first to\ngive a short overview of this research field and then to consider tangled, yet\nunclear issues and outline the ways of oncoming studies. A special emphasis is\ngiven on the specific structure of grain boundaries in ultrafine grained\nmaterials processed by SPD, on grain boundary segregation, on interfacial\nmixing linked to heterophase boundaries and on grain boundary diffusion. The\nconnection between these unique features and the mechanical properties or the\nthermal stability of the ultrafine grained alloys is also discussed.",
        "positive": "Understanding and Designing the Spin-Driven Thermoelectrics: While the thermoelectric materials progress based on the engineering of\nelectronic and phononic characteristics is reaching a plateau, adding the spin\ndegree of freedom has the potential to open a new landscape for alternative\nthermoelectric materials. Here we present the concepts, current understanding,\nand guidelines for designing spin-driven thermoelectrics. We show that the\ninterplay between the spin and heat currents in entropy transport via charge\ncarriers can offer a strategic path to enhance the electronic thermopower. The\nclassical antiferromagnetic semiconductor manganese telluride (MnTe) is chosen\nas the case study due to its significant spin-mediated thermoelectric\nproperties. We show that although the spin-disorder scattering reduces the\ncarrier mobility in magnetic materials, spin entropy, magnon, and paramagnon\ncarrier drags can dominate over and significantly enhance the thermoelectric\npower factor and hence zT. Finally, several guidelines are drawn based on the\ncurrent understandings for designing high-performance spin-driven\nthermoelectric materials."
    },
    {
        "anchor": "Pressure induced switching in ferroelectrics: on the junction between\n  physics and electrochemistry: Pressure-induced polarization switching in ferroelectric thin films has\nemerged as a powerful method for domain patterning, allowing to create\npredefined domain patterns on free surfaces and under thin conductive top\nelectrodes. However, the mechanisms for pressure induced polarization switching\nin ferroelectrics remain highly controversial, with flexoelectricity,\npolarization rotation and suppression, and bulk and surface electrochemical\nprocesses all being potentially relevant. Here we classify possible pressure\ninduced switching mechanisms, perform elementary estimates, and study in depth\nusing phase-field modelling. We show that magnitudes of these effects are\nremarkably close, and give rise to complex switching diagrams as a function of\npressure and film thickness with non-trivial topology or switchable and\nnon-switchable regions.",
        "positive": "Density-functional tight-binding for beginners: This article is a pedagogical introduction to density-functional\ntight-binding (DFTB) method. We derive it from the density-functional theory,\ngive the details behind the tight-binding formalism, and give practical recipes\nfor parametrization: how to calculate pseudo-atomic orbitals and matrix\nelements, and especially how to systematically fit the short-range repulsions.\nOur scope is neither to provide a historical review nor to make performance\ncomparisons, but to give beginner's guide for this approximate, but in many\nways invaluable, electronic structure simulation method--now freely available\nas an open-source software package, hotbit."
    },
    {
        "anchor": "Topologically Linked Crystals: We discovered a new class of topological crystals, namely linked rings of\ncrystals. Two rings of tantalum triselenide (TaSe3) single crystals were linked\nto each other while crystal growing. The topology of the crystal form is called\na \"Hopf link\", which is the simplest link involving just two component unknots\nlinked together exactly once. The feature of the crystals is not covered by the\nconventional crystallography.",
        "positive": "Stabilizing isolated skyrmions at low magnetic fields exploiting\n  vanishing magnetic anisotropy: Skyrmions are topologically protected non-collinear magnetic structures.\nTheir stability and dynamics, arising from their topological character, have\nmade them ideal information carriers e.g. in racetrack memories. The success of\nsuch a memory critically depends on the ability to stabilize and manipulate\nskyrmions at low magnetic fields. The driving force for skyrmion formation is\nthe non-collinear Dzyaloshinskii-Moriya exchange interaction (DMI) originating\nfrom spin-orbit coupling (SOC). It competes with both the nearest neighbour\nHeisenberg exchange interaction and the magnetic anisotropy, which favour\ncollinear states. While skyrmion lattices might evolve at vanishing magnetic\nfields, the formation of isolated skyrmions in ultra-thin films so far required\nthe application of an external field which can be as high as several T. Here,\nwe show that isolated skyrmions in a monolayer (ML) of Co epitaxially grown on\na Ru(0001) substrate can be stabilized at magnetic fields as low as 100 mT.\nEven though SOC is weak in the 4d element Ru, a homochiral spin spiral ground\nstate and isolated skyrmions could be detected and laterally resolved using a\ncombination of tunneling and anisotropic tunneling magnetoresistance effect in\nspin-sensitive scanning tunneling microscopy (STM). Density functional theory\n(DFT) calculations confirm these chiral magnetic textures, even though the\nstabilizing DMI interaction is weak. We find that the key factor is the absence\nof magnetocristalline anisotropy in this system which enables non-collinear\nstates to evolve in spite of weak SOC, opening up a wide choice of materials\nbeyond 5d elements."
    },
    {
        "anchor": "Photoemission Spectroscopy and Orbital Imaging from Koopmans-Compliant\n  Functionals: The determination of spectral properties from first principles can provide\npowerful connections between microscopic theoretical predictions and\nexperimental data, but requires complex electronic-structure formulations that\nfall outside the domain of applicability of common approaches, such as\ndensity-functional theory. We show here that Koopmans-compliant functionals,\nconstructed to enforce piecewise linearity in energy functionals with respect\nto fractional occupations - i.e. with respect to charged excitations - provide\nmolecular photoemission spectra and momentum maps of Dyson orbitals that are in\nexcellent agreement with experimental ultraviolet photoemission spectroscopy\nand orbital tomography data. These results highlight the role of\nKoopmans-compliant functionals as accurate and inexpensive quasiparticle\napproximations to the spectral potential.",
        "positive": "Mechanism of cathodic protection of iron and steel in porous media: Cathodic protection (CP) was introduced two centuries ago and since has found\nwidespread application in protecting structures such as pipelines, offshore\ninstallations, and bridges from corrosion. Despite its extensive use, the\nfundamental working mechanism of CP remains debated, particularly for metals in\nporous media such as soil. Here, we offer resolution to the long-standing\ndebate by employing in-situ and ex-situ characterisation techniques coupled\nwith electrochemical measurements to characterise the spatio-temporal changes\noccurring at the steel-electrolyte interface. We show that upon CP, the\ninterfacial electrolyte undergoes alkalinisation and deoxygenation, and that\ndepending on polarisation conditions, an iron oxide film can simultaneously\nform on the steel surface. We further demonstrate that these changes in\ninterfacial electrolyte chemistry and steel surface state result in altered\nanodic and cathodic reactions and their kinetics. We propose a mechanism of CP\nthat integrates the long debated theories, based on both concentration and\nactivation polarisation, complimentarily. Implications of this coherent\nscientific understanding for enhancing corrosion protection technologies and\nthe safe, economic, and environmental-friendly operation of critical\nsteel-based infrastructures are discussed."
    },
    {
        "anchor": "Coupled opto-electronic simulation of organic bulk-heterojunction solar\n  cells: parameter extraction and sensitivity analysis: A general problem arising in computer simulations is the number of material\nand device parameters, which have to be determined by dedicated experiments and\nsimulation-based parameter extraction. In this study we analyze measurements of\nthe short-circuit current dependence on the active layer thickness and\ncurrent-voltage curves in poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid\nmethyl ester (P3HT:PCBM) based solar cells. We have identified a set of\nparameter values including dissociation parameters that describe the\nexperimental data. The overall agreement of our model with experiment is good,\nhowever a discrepancy in the thickness dependence of the current-voltage curve\nquestions the influence of the electric field in the dissociation process. In\naddition transient simulations are analyzed which show that a measurement of\nthe turn-off photocurrent can be useful for estimating charge carrier\nmobilities.",
        "positive": "Interlayer electronic hybridization leads to exceptional\n  thickness-dependent vibrational properties in few-layer black phosphorus: Stacking two-dimensional (2D) materials into multi-layers or\nheterostructures, known as van der Waals (vdW) epitaxy, is an essential degree\nof freedom for tuning their properties on demand. Few-layer black phosphorus\n(FLBP), a material with high potential for nano- and optoelectronics\napplications, appears to have interlayer couplings much stronger than graphene\nand other 2D systems. Indeed, these couplings call into question whether the\nstacking of FLBP can be governed only by vdW interactions, which is of crucial\nimportance for epitaxy and property refinement. Here, we perform a theoretical\ninvestigation of the vibrational properties of FLBP, which reflect directly its\ninterlayer coupling, by discussing six Raman-observable phonons, including\nthree optical, one breathing, and two shear modes. With increasing sample\nthickness, we find anomalous redshifts of the frequencies for each optical mode\nbut a blueshift for the armchair shear mode. Our calculations also show\nsplitting of the phonon branches, due to anomalous surface phenomena, and\nstrong phonon-phonon coupling. By computing uniaxial stress effects,\ninter-atomic force constants, and electron densities, we provide a compelling\ndemonstration that these properties are the consequence of strong and highly\ndirectional interlayer interactions arising from electronic hybridization of\nthe lone electron-pairs of FLBP, rather than from vdW interactions. This\nexceptional interlayer coupling mechanism controls the stacking stability of BP\nlayers and thus opens a new avenue beyond vdW epitaxy for understanding the\ndesign of 2D heterostructures."
    },
    {
        "anchor": "Process stabilization by peak current regulation in reactive high-power\n  impulse magnetron sputtering of hafnium nitride: A simple and cost effective approach to stabilize the sputtering process in\nthe transition zone during reactive high-power impulse magnetron sputtering\n(HiPIMS) is proposed. The method is based on real-time monitoring and control\nof the discharge current waveforms. To stabilize the process conditions at a\ngiven set point, a feedback control system was implemented that automatically\nregulates the pulse frequency, and thereby the average sputtering power, to\nmaintain a constant maximum discharge current. In the present study, the\nvariation of the pulse current waveforms over a wide range of reactive gas\nflows and pulse frequencies during a reactive HiPIMS process of Hf-N in an\nAr-N2 atmosphere illustrates that the discharge current waveform is a an\nexcellent indicator of the process conditions. Activating the reactive HiPIMS\npeak current regulation, stable process conditions were maintained when varying\nthe N2 flow from 2.1 to 3.5 sccm by an automatic adjustment of the pulse\nfrequency from 600 Hz to 1150 Hz and consequently an increase of the average\npower from 110 to 270 W. Hf-N films deposited using peak current regulation\nexhibited a stable stoichiometry, a nearly constant power-normalized deposition\nrate, and a polycrystalline cubic phase Hf-N with (111)- preferred orientation\nover the entire reactive gas flow range investigated. The physical reasons for\nthe change in the current pulse waveform for different process conditions are\ndiscussed in some detail.",
        "positive": "Revealing Controllable Anisotropic Magnetoresistance in Spin Orbit\n  Coupled Antiferromagnet Sr2IrO4: Antiferromagnetic spintronics actively introduces new principles of magnetic\nmemory, in which the most fundamental spin-dependent phenomena, i.e.\nanisotropic magnetoresistance effects, are governed by an antiferromagnet\ninstead of a ferromagnet. A general scenario of the antiferromagnetic\nanisotropic magnetoresistance effects mainly stems from the magnetocrystalline\nanisotropy related to spin-orbit coupling. Here we demonstrate magnetic field\ndriven contour rotation of the fourfold anisotropic magnetoresistance in bare\nantiferromagnetic Sr2IrO4/SrTiO3 (001) thin films hosting a strong spin-orbit\ncoupling induced Jeff=1/2 Mott state. Concurrently, an intriguing minimal in\nthe magnetoresistance emerges. Through first principles calculations, the\nband-gap engineering due to rotation of the Ir isospins is revealed to be\nresponsible for these emergent phenomena, different from the traditional\nscenario where relatively more conductive state was obtained usually when\nmagnetic field was applied along the magnetic easy axis. Our findings\ndemonstrate a new efficient route, i.e. via the novel Jeff=1/2 state, to\nrealize controllable anisotropic magnetoresistance in antiferromagnetic\nmaterials."
    },
    {
        "anchor": "Entropy engineering and tunable magnetic order in the spinel high\n  entropy oxide: Spinel oxides are an ideal setting to explore the interplay between\nconfigurational entropy, site selectivity, and magnetism in high entropy\noxides. In this work we characterize the magnetic properties of the spinel\n(Cr,Mn,Fe,Co,Ni)$_3$O$_4$ and study the evolution of its magnetism as a\nfunction of non-magnetic gallium substitution. Across the range of compositions\nstudied here, from 0% to 40% Ga, magnetic susceptibility and powder neutron\ndiffraction measurements show that ferrimagnetic order is robust in the spinel\nHEO. However, we also find that the ferrimagnetic order is highly tunable, with\nthe ordering temperature, saturated and sublattice moments, and magnetic\nhardness all varying significantly as a function of Ga concentration. Through\nx-ray absorption and magnetic circular dichroism, we are able to correlate this\nmagnetic tunability with strong site selectivity between the various cations\nand the tetrahedral and octahedral sites in the spinel structure. In\nparticular, we find that while Ni and Cr are largely unaffected by the\nsubstitution with Ga, the occupancies of Mn, Co, and Fe are each significantly\nredistributed. Ga substitution also requires an overall reduction in the\ntransition metal valence, and this is entirely accommodated by Mn. Finally, we\nshow that while site selectivity has an overall suppressing effect on the\nconfigurational entropy, over a certain range of compositions, Ga substitution\nyields a striking increase in the configurational entropy and may confer\nadditional stabilization. Spinel oxides can be tuned seamlessly from the\nlow-entropy to the high-entropy regime, making this an ideal platform for\nentropy engineering.",
        "positive": "Development of the temperature-dependent interatomic potential for\n  molecular dynamics simulation of metal irradiated with an ultrashort pulse\n  laser: Laser ablation is often explained by a two-temperature model (TTM) with\ndifferent electron and lattice temperatures. To realize a classical molecular\ndynamics simulation of the TTM, we propose an extension of the embedded atom\nmethod to construct an interatomic potential that is dependent on the electron\ntemperature. This method is applied to copper, and its validity is demonstrated\nby comparison of several physical properties, such as the energy-volume curve,\nphonon dispersion, electronic heat capacity, ablation threshold, and mean\nsquare displacement of atoms, with those of finite-temperature density\nfunctional theory."
    },
    {
        "anchor": "Gate tunable optical absorption and band structure of twisted bilayer\n  graphene: We report the infrared transmission measurement on electrically gated twisted\nbilayer graphene. The optical absorption spectrum clearly manifests the\ndramatic changes such as the splitting of inter-linear-band absorption step,\nthe shift of inter-van Hove singularity transition peak, and the emergence of\nvery strong intra-valence (intra-conduction) band transition. These anomalous\noptical behaviors demonstrate consistently the non-rigid band structure\nmodification created by the ion-gel gating through the layer-dependent Coulomb\nscreening. We propose that this screening-driven band modification is an\nuniversal phenomenon that persists to other bilayer crystals in general,\nestablishing the electrical gating as a versatile technique to engineer the\nband structures and to create new types of optical absorptions that can be\nexploited in electro-optical device application.",
        "positive": "On the use of SRIM for calculating arc-dpa exposure: We propose two methods for evaluating athermal recombination corrected (arc)\ndisplacement damage parameters in ion irradiations employing the computer code\nSRIM (Stopping and Range of Ions in Matter). The first method consists of\npost-processing the detailed SRIM output for all simulated damage events and\nre-calculating according to the arc damage model. In the second method, an\napproximate empirical formula is devised which gives the average displacements\nin the arc damage model as a function of the corresponding quantity according\nto the standard Norgett-Robinson-Torrens model, which is readily obtained from\nSRIM."
    },
    {
        "anchor": "Design of high-strength refractory complex solid-solution alloys: Nickel-based superalloys and near-equiatomic high-entropy alloys containing\nMolybdenum are known for higher temperature strength and corrosion resistance.\nYet, complex solid-solution alloys offer a huge design space to tune for\noptimal properties at slightly reduced entropy. For refractory Mo-W-Ta-Ti-Zr,\nwe showcase KKR electronic-structure methods via the coherent-potential\napproximation to identify alloys over 5-dimensional design space with improved\nmechanical properties and necessary global (formation enthalpy) and local\n(short-range order) stability. Deformation is modeled with classical molecular\ndynamic simulations, validated from our first-principles data. We predict\ncomplex solid-solution alloys of improved stability with greatly enhanced\nmodulus of elasticity ($3\\times$ at 300 K) over near-equiatomic cases, as\nvalidated experimentally, and with higher moduli above 500~K over commercial\nalloys ($2.3\\times$ at 2000 K). We also show that optimal complex\nsolid-solution alloys are not described well by classical potentials due to\ncritical electronic effects.",
        "positive": "Physics-informed neural networks for modeling rate- and\n  temperature-dependent plasticity: This work presents a physics-informed neural network (PINN) based framework\nto model the strain-rate and temperature dependence of the deformation fields\nin elastic-viscoplastic solids. To avoid unbalanced back-propagated gradients\nduring training, the proposed framework uses a simple strategy with no added\ncomputational complexity for selecting scalar weights that balance the\ninterplay between different terms in the physics-based loss function. In\naddition, we highlight a fundamental challenge involving the selection of\nappropriate model outputs so that the mechanical problem can be faithfully\nsolved using a PINN-based approach. We demonstrate the effectiveness of this\napproach by studying two test problems modeling the elastic-viscoplastic\ndeformation in solids at different strain rates and temperatures, respectively.\nOur results show that the proposed PINN-based approach can accurately predict\nthe spatio-temporal evolution of deformation in elastic-viscoplastic materials."
    },
    {
        "anchor": "Tuning metal-insulator transitions in epitaxial V$_2$O$_3$ thin films: We present a study of the synthesis of epitaxial V$_2$O$_3$ films on\n$c$-plane Al$_2$O$_3$ substrates by reactive dc-magnetron sputtering. The\nresults reveal a temperature window, at substantially lower values than\npreviously reported, wherein epitaxial films can be obtained when deposited on\n[0001] oriented surfaces. The films display a metal-insulator transition with a\nchange in resistance of up to four orders of magnitude, strongly dependent on\nthe O$_2$ partial pressure during deposition. While the electronic properties\nof the films show sensitivity to the amount of O$_2$ present during deposition\nof the films, their crystallographic structure and surface morphology of\natomically flat terraced structures with up to micrometer dimensions are\nmaintained. The transition temperature, as well as the scale of the\nmetal-insulator transition, is correlated to the stoichiometry and local strain\nin the films controllable by the deposition parameters.",
        "positive": "Spin canting in a Dy-based Single-Chain Magnet with dominant\n  next-nearest neighbor antiferromagnetic interactions: We investigate theoretically and experimentally the static magnetic\nproperties of single crystals of the molecular-based Single-Chain Magnet (SCM)\nof formula [Dy(hfac)$_{3}$NIT(C$_{6}$H$_{4}$OPh)]$_{\\infty}$ comprising\nalternating Dy$^{3+}$ and organic radicals. A peculiar inversion between maxima\nand minima in the angular dependence of the magnetic molar susceptibility\n$\\chi_{M}$ occurs on increasing temperature. Using information regarding the\nmonomeric building block as well as an {\\it ab initio} estimation of the\nmagnetic anisotropy of the Dy$^{3+}$ ion, this anisotropy-inversion phenomenon\ncan be assigned to weak one-dimensional ferromagnetism along the chain axis.\nThis indicates that antiferromagnetic next-nearest-neighbor interactions\nbetween Dy$^{3+}$ ions dominate, despite the large Dy-Dy separation, over the\nnearest-neighbor interactions between the radicals and the Dy$^{3+}$ ions.\nMeasurements of the field dependence of the magnetization, both along and\nperpendicularly to the chain, and of the angular dependence of $\\chi_{M}$ in a\nstrong magnetic field confirm such an interpretation. Transfer matrix\nsimulations of the experimental measurements are performed using a classical\none-dimensional spin model with antiferromagnetic Heisenberg exchange\ninteraction and non-collinear uniaxial single-ion anisotropies favoring a\ncanted antiferromagnetic spin arrangement, with a net magnetic moment along the\nchain axis. The fine agreement obtained with experimental data provides\nestimates of the Hamiltonian parameters, essential for further study of the\ndynamics of rare-earths based molecular chains."
    },
    {
        "anchor": "Evidence for dielectric aging due to progressive 180 domain wall pinning\n  in polydomain Pb(Zr0.45Ti0.55)O3 thin films: An evidence that the dielectric ageing in the polydomain Pb(Zr0.45Ti0.55)O3\nthin films is controlled by progressive pinning of 180 domain walls is\npresented. To provide such a conclusion, we use a general method, which is\nbased on the study of the time evolution of the nonlinear, but anhysteretic,\ndielectric response of the ferroelectric to a weak electric field. A\nthermodynamic model of the ferroelectric system where the dielectric response\nis controlled by bending movements of pinned 180 domain walls is developed.\nWithin this model, the nonlinear permittivity of the ferroelectric is expressed\nas a function of the microstructural parameters of the domain pattern. It is\nshown that using the analysis of the time evolution of the nonlinear\npermittivity, it is possible to estimate changes in the concentration of the\npinning centers that block the movements of the 180 domain walls during aging\nin polydomain perovskite ferroelectrics.",
        "positive": "Systematic control of carrier concentration and resisitivity in RF\n  sputtered Zinc oxide thin films: RF sputtered ZnO and Al:ZnO films are attractive transparent conductive\noxides for fabrication of opto-electronic devices. In this paper we present\nefforts to control carrier concentration and mobility of ZnO/Al:ZnO thin films\nby controlling deposition parameters (RF power, pressure and substrate\ntemperature. Al:ZnO thin film with resistivity as low as $\\rho$ = $3.8\\times\n10^{-4}$ $\\Omega$.cm at deposition temperature of 250{\\deg}C has been achieved.\nZinc oxide thin film with low resistivity of $\\rho$ = $3.7\\times 10^{-2}$\n$\\Omega$.cm and high electron mobility of $30$ $\\mathrm{cm^{-2}V^{-1}s^{-1}}$\nat deposition temperature of 250{\\deg}C with acceptable electronic parameters\nstability has been obtained.Light transmission of Al:ZnO and ZnO samples\ndeposited on glass at different substrate temperature has been studied.\nInvestigation were made to assess the effect of deposition temperature on the\nphotoluminescence spectra (PL) of ZnO/Al:ZnO sputtered on silicon and glass\nsubstrate. The evolution of near band edge (NBE) and deep level emission (DLE)\nphotoluminescence peaks with deposition temperature in ZnO/Al:ZnO sputtered on\nSilicon and glass substrate have been studied."
    },
    {
        "anchor": "Ballistic transport at room temperature in micrometer size multigraphene: The intrinsic values of the carriers mobility and density of the graphene\nlayers inside graphite, the well known structure built on these layers in the\nBernal stacking configuration, are not well known mainly because most of the\nresearch was done in rather bulk samples where lattice defects hide their\nintrinsic values. By measuring the electrical resistance through\nmicrofabricated constrictions in micrometer small graphite flakes of a few tens\nof nanometers thickness we studied the ballistic behavior of the carriers. We\nfound that the carriers' mean free path is micrometer large with a mobility\n$\\mu \\simeq 6 \\times 10^6 $cm$^2$/Vs and a carrier density $n \\simeq 7 \\times\n10^8 $cm$^{-2}$ per graphene layer at room temperature. These distinctive\ntransport and ballistic properties have important implications for\nunderstanding the values obtained in single graphene and in graphite as well as\nfor implementing this last in nanoelectronic devices.",
        "positive": "Phase diagram of the ferroelectric-relaxor\n  (1-x)PbMg(1/3)Nb(2/3)O3-xPbTiO3: Synchrotron x-ray powder diffraction measurements have been performed on\nunpoled ceramic samples of (1-x)PbMg(1/3)Nb(2/3)O3-xPbTiO3 (PMN-xPT) with 30%<=\nx<= 39% as a function of temperature around the morphotropic phase boundary\n(MPB), which is the line separating the rhombohedral and tetragonal phases in\nthe phase diagram. The experiments have revealed very interesting features\npreviously unknown in this or related systems. The sharp and well-defined\ndiffraction profiles observed at high and intermediate temperatures in the\ncubic and tetragonal phases, respectively, are in contrast to the broad\nfeatures encountered at low temperatures. These peculiar characteristics, which\nare associated with the monoclinic phase of MC-type previously reported by Kiat\net al and Singh et al., can only be interpreted as multiple coexisting\nstructures with MC as the major component. An analysis of the diffraction\nprofiles has allowed us to properly characterize the PMN-xPT phase diagram and\nto determine the stability region of the monoclinic phase, which extends from\nx= 31% to x= 37% at 20 K. The complex lansdcape of observed phases points to an\nenergy balance between the different PMN-xPT phases which is intrinsically much\nmore delicate than that of related systems such as PbZr(1-x)TixO3 or\n(1-x)PbZn(1/3)Nb(1/3)O3-xPbTiO3. These observations are in good accord with an\noptical study of x= 33% by Xu et al., who observed monoclinic domains with\nseveral different polar directions coexisting with rhombohedral domains, in the\nsame single crystal."
    },
    {
        "anchor": "Free energy and metastable states in the square-lattice J1-J2 Ising\n  model: We calculate the (restricted) free energy as a function of polarization for\nthe square-lattice J1-J2 Ising model using the Random local field approximation\n(RLFA) and Monte Carlo (MC) simulations. Here we consider mainly coupling\nconstants in the range 0 < J2 < 1/2 at J1 = - 1, for which the ground state is\nferromagnetic (or N{\\'e}el antiferromagnetic when J1 = 1). Within RLFA, a\nmetastable state with zero polarization is present in the ordered phase, which\nwas recently discussed by V.A. Abalmasov and B.E. Vugmeister, Phys. Rev. E 107,\n034124 (2023). In addition, the free energy calculated within RLFA indicates a\ngeometric slab-droplet phase transition at low temperature, which cannot be\ndetected in the mean field approximation. In turn, exact calculations of the\nfree energy for the sample size L = 6 and MC simulations for L = 10 reveal\nmetastable states with a wide range of polarization values in the ordered\nphase, the origin of which we discuss. The calculations also reveal additional\nslab-droplet transitions (at J2 > 0.25). These findings enrich our knowledge of\nthe J1-J2 Ising model and the RLFA as a useful theoretical tool to study phase\ntransitions in spin systems.",
        "positive": "Highly Conductive 3D Nano-Carbon: Stacked Multilayer Graphene System\n  with Interlayer Decoupling: We investigate electrical conduction and breakdown behavior of 3D\nnano-carbon-stacked multilayer graphene (s-MLG) system with complete interlayer\ndecoupling. The s-MLG is prepared by transferring and stacking large-area\nCVD-grown graphene monolayers, followed by wire patterning and plasma etching.\nRaman spectroscopy was used to confirm the layer number. The D-band peak\nindicates low defect level in the samples. Electrical current stressing induced\ndoping is performed to shift the charge-neutrality Dirac point and decrease the\ngraphene/metal contact resistance, improving the overall electrical conduction.\nBreakdown experiments show the current-carrying capacity of s-MLG is largely\nenhanced as compared with that of monolayer graphene."
    },
    {
        "anchor": "Spin-reorientation in YbFeO_3: Precise measurements of YbFeO_3 magnetization in the spin-reoirentation\ntemperature interval are performed. It is shown that ytterbium orthoferrite is\nwell described by a recently developed modified mean field theory developed for\nErFeO_3. This validates the conjecture about the essential influence of the\nrare earth ion's anisotropic paramagnetism on the magnetization behavior in the\nreorientation regions of all orthoferrites with Gamma{4} -> Gamma{24} ->\nGamma{2} phase transitions.",
        "positive": "Exchange bias phenomenology and models of core/shell nanoparticles: Some of the main experimental observations related to the occurrence of\nexchange bias in magnetic systems are reviewed, focusing the attention on the\npeculiar phenomenology associated to nanoparticles with core/shell structure as\ncompared to thin film bilayers. The main open questions posed by the\nexperimental observations are presented and contrasted to existing theories and\nmodels for exchange bias formulated up to date. We also present results of\nsimulations based on a simple model of a core/shell nanoparticle in which the\nvalues of microscopic parameters such as anisotropy and exchange constants can\nbe tuned in the core, shell and at the interfacial regions, offering new\ninsight on the microscopic origin of the experimental phenomenology. A detailed\nstudy of the of the magnetic order of the interfacial spins shows compelling\nevidence that most of the experimentally observed effects can be qualitatively\naccounted within the context of this model and allows also to quantify the\nmagnitude of the loop shifts with striking agreement with the macroscopic\nobserved values."
    },
    {
        "anchor": "Current-induced exchange switching magnetic junctions with cubic\n  anisotropy of the free layer: The stability is analyzed of the equilibrium configurations of a magnetic\njunction with a free layer that has cubic symmetry and two anisotropy axes in\nthe layer plane. Different variants of the switching between various\nconfigurations are considered. A possibility is shown of the substantial\nlowering of the threshold current density needed for the switching. Numerical\nsimulation is made of the switching dynamics for various configurations.",
        "positive": "A new polymorphic material? Structural degeneracy of ZrMn_2: Based on density functional calculations, we propose that ZrMn_2 is a\npolymorphic material. We predict that at low temperatures the cubic C15, and\nthe hexagonal C14 and C36 structures of the Laves phase compound ZrMn_2 are\nnearly equally stable within 0.3 kJmol^{-1} or 30 K. This degeneracy occurs\nwhen the Mn atoms magnetize spontaneously in a ferromagnetic arrangement\nforming the states of lowest energy. From the temperature dependent free\nenergies at T approx 160K we predict a transition from the most stable C15 to\nthe C14 structure, which is the experimentally observed structure at elevated\ntemperatures."
    },
    {
        "anchor": "Magnetic and chemical properties of Cr-based films grown on GaAs(001): We have investigated the magnetic and chemical properties of very thin Cr\nfilms, CrAs, and arsenized Cr grown by molecular beam epitaxy on Ga As (001),\nusing x-ray photoemission spectroscopy and SQUID magnetometry. Distintic\npreparation procedures have been used with the purpose to undestand the origin\nof the ferromagneti signal observed for this system. It results that Ga\nsegregation and chemical reactivity between Ga and Cr have negligible\ncontribution in the formation of different thi films. A clear ferromagnetic\nresponse even at room temperature suggests the existence of a very thin\ninterfacial layer formed that can eventually be burid during the growth\nprocess.",
        "positive": "Nonlinear electronic excitations in crystalline solids using\n  meta-generalized gradient approximation and hybrid functional in\n  time-dependent density functional theory: We develop numerical methods to calculate electron dynamics in crystalline\nsolids in real-time time-dependent density functional theory employing\nexchange-correlation potentials which reproduce band gap energies of\ndielectrics; a meta generalized gradient approximation (meta-GGA) proposed by\nTran and Blaha [Phys. Rev. Lett. 102, 226401 (2009)] (TBm-BJ) and a hybrid\nfunctional proposed by Heyd, Scuseria, and Ernzerhof [J. Chem. Phys. 118, 8207\n(2003)] (HSE). In time evolution calculations employing the TB-mBJ potential,\nwe have found it necessary to adopt a predictor-corrector step for stable\ntime-evolution. Since energy functional is not known for the TB-mBJ potential,\nwe propose a method to evaluate electronic excitation energy without referring\nto the energy functional. Calculations using the HSE hybrid functional is\ncomputationally expensive due to the nonlocal Fock-like term. We develop a\ncomputational method for the operation of the Fock-like term in Fourier space,\nfor which we employ massively parallel computers equipped with graphic\nprocessing units. To demonstrate significances of utilizing potentials\nproviding correct band gap energies, we compare electronic excitations induced\nby femtosecond laser pulses using the TB-mBJ, HSE, and a simple local density\napproximation (LDA). At low laser intensities, electronic excitations are found\nto be sensitive to the band gap energy: results using TB-mBJ and HSE are close\nto each other, while the excitation of the LDA calculation is more intensive\nthan the others. At high laser intensities close to a damage threshold, we have\nfound that electronic excitation energies are similar among the three cases."
    },
    {
        "anchor": "Ga+, In+ and Tl+ Impurities in Alkali Halide Crystals: Distortion Trends: A computational study of the doping of alkali halide crystals (AX: A = Na, K;\nX = Cl, Br) by ns2 cations (Ga+, In+ and Tl+) is presented. Active clusters of\nincreasing size (from 33 to 177 ions) are considered in order to deal with the\nlarge scale distortions induced by the substitutional impurities. Those\nclusters are embedded in accurate quantum environments representing the\nsurrounding crystalline lattice. The convergence of the distortion results with\nthe size of the active cluster is analyced for some selected impurity systems.\nThe most important conclusion from this study is that distortions along the\n(100) and (110) crystallographic directions are not independent. Once a\nreliable cluster model is found, distortion trends as a function of impurity,\nalkali cation and halide anion are identified and discussed. These trends may\nbe useful when analycing other cation impurities in similar host lattices.",
        "positive": "First-principles study of TMNan (TM= Cr, Mn, Fe, Co, Ni; n = 4-7)\n  clusters: Geometry, electronic structure, and magnetic properties of TMNan (TM=Cr-Ni; n\n= 4-7) clusters are studied within a gradient corrected density functional\ntheory (DFT) framework. Two complementary approaches, the first adapted to\nall-electron calculations on free clusters, and the second been on plane wave\nprojector augmented wave (PAW) method within a supercell approach are used.\nExcept for NiNan, the clusters in this series are found to retain the atomic\nmoments of the TM atoms, and the magnetic moment presented an odd-even\noscillation with respect to the number of Na atoms. The origin of these\nodd-even oscillations is explained from the nature of chemical bonding in these\nclusters. Differences and similarities between the chemical bonding and the\nmagnetic properties of these clusters and the TMNan (TM = Sc, V and Ti; n =\n4-6) clusters on one hand, and TM-doped Au and Ag clusters on the other hand,\nare discussed."
    },
    {
        "anchor": "High resolution electron backscatter diffraction study on the\n  heterogeneities of tetragonal distortion in Fe-C martensite at the\n  microstructural scale: The spatial variation in martensite tetragonality (c/a ratio) in Fe-0.77C\n(wt.%) alloy was investigated by means of pattern matching of electron\nbackscatter diffraction patterns combined with high angular resolution electron\nbackscatter diffraction analysis. It was found that the c/a ratio varies within\na martensite block and between blocks. The c/a variation within a block is\nparticularly evident in the vicinity of grain boundaries and shear strains are\nalso present in addition to tetragonal distortion. The c/a variation between\nblocks is more apparent than that within a block. The lattice parameter\nfrequency profile predicted by our approach well matches with the X-ray\ndiffraction profile from the same material by assuming reasonable residual\nstrain acting on a- and b-axes. The heterogeneities of the crystal distortion\nare brought by a decrease and scatter in solid solution carbon and in carbon\nordering as a result of the martensite transformation sequence as well as\nheterogeneous residual strain.",
        "positive": "Leveraging Language Representation for Material Recommendation, Ranking,\n  and Exploration: Data-driven approaches for material discovery and design have been\naccelerated by emerging efforts in machine learning. However, general\nrepresentations of crystals to explore the vast material search space remain\nlimited. We introduce a material discovery framework that uses natural language\nembeddings derived from language models as representations of compositional and\nstructural features. The discovery framework consists of a joint scheme that\nfirst recalls relevant candidates, and next ranks the candidates based on\nmultiple target properties. The contextual knowledge encoded in language\nrepresentations conveys information about material properties and structures,\nenabling both representational similarity analysis for recall, and multi-task\nlearning to share information across related properties. By applying the\nframework to thermoelectrics, we demonstrate diversified recommendations of\nprototype structures and identify under-studied high-performance material\nspaces. The recommended materials are corroborated by first-principles\ncalculations and experiments, revealing novel materials with potential high\nperformance. Our framework provides a task-agnostic means for effective\nmaterial recommendation and can be applied to various material systems."
    },
    {
        "anchor": "Spin-lattice coupling in an epitaxial NdFeO3 thin film: Rare-earth orthoferrite RFeO3 materials such as NdFeO3 are strongly studied\nbecause of their fascinating magnetic properties and their potential\napplications. Here, we show the successful epitaxial synthesis of\nparasitic-free NFO thin film by pulsed laser deposition on (001)-SrTiO3.\nHigh-resolution X-ray diffraction shows a coherent growth and a tetragonal-like\nstructure of a tensile strained 80 nm thick NFO film in contrast with the bulk\northorhombic state. Room temperature magnetometry indicates a bulk-like\nantiferromagnetic state for the NFO film. Temperature-dependent X-ray\ndiffraction and magnetometry highlight a significant spin-lattice coupling at\nthe Neel Temperature while a new magneto-structural instability is discovered\naround 250{\\deg}C that needs further investigation.",
        "positive": "Ab initio prediction of an order-disorder transition in Mg$_2$GeO$_4$:\n  implication for the nature of super-Earth's mantles: Here we present an ab initio prediction of an order-disorder transition (ODT)\nfrom $I\\bar{4}2d$-type to a Th$_3$P$_4$-type phase in the cation sublattices of\nMg$_2$GeO$_4$, a post-post-perovskite (post-PPv) phase. This uncommon type of\nprediction is achieved by carrying out a high-throughput sampling of atomic\nconfigurations in a 56-atom supercell followed by a Boltzmann ensemble\nstatistics calculation. Mg$_2$GeO$_4$ is a low-pressure analog of\n$I\\bar{4}2d$-type Mg$_2$SiO$_4$, a predicted major planet-forming phase of\nsuper-Earths' mantles. Therefore, a similar ODT is anticipated in\n$I\\bar{4}2d$-type Mg$_2$SiO$_4$ as well, which should impact the internal\nstructure and dynamics of these planets. The prediction of this\nTh$_3$P$_4$-type phase in Mg$_2$GeO$_4$ enhances further the relationship\nbetween the crystal structures of Earth/planet-forming silicates and oxides at\nextreme pressures and those of rare-earth sesquisulfides at low pressures."
    },
    {
        "anchor": "Theory of the ground state spin of the NV- center in diamond: II. Spin\n  solutions, time-evolution, relaxation and inhomogeneous dephasing: The ground state spin of the negatively charged nitrogen-vacancy center in\ndiamond has many exciting applications in quantum metrology and solid state\nquantum information processing, including magnetometry, electrometry, quantum\nmemory and quantum optical networks. Each of these applications involve the\ninteraction of the spin with some configuration of electric, magnetic and\nstrain fields, however, to date there does not exist a detailed model of the\nspin's interactions with such fields, nor an understanding of how the fields\ninfluence the time-evolution of the spin and its relaxation and inhomogeneous\ndephasing. In this work, a general solution is obtained for the spin in any\ngiven electric-magnetic-strain field configuration for the first time, and the\ninfluence of the fields on the evolution of the spin is examined. Thus, this\nwork provides the essential theoretical tools for the precise control and\nmodeling of this remarkable spin in its current and future applications.",
        "positive": "Spin Singlet Formation from S = 1/2 Tetrahedral Clusters: Muon spin relaxation ($\\mu$SR) and nuclear magnetic resonance (NMR)\nexperiments revealed that the spin singlet state with an excitation gap of\n$\\sim$200 K is realized from $S = 1/2$ Nb$_4$ tetrahedral clusters in a cluster\nMott insulator GaNb$_4$S$_8$. The intercluster cooperative phenomenon to the\nsinglet state at $T_\\mathrm{S} = 32$ K is triggered by intracluster Jahn-Teller\ntype structural instability developed from $\\sim$$3T_\\mathrm{S}$. Referring to\nthe lattice symmetry, the formation of Nb$_8$ octamer (Nb$_4$--Nb$_4$ bond) is\nsuggested."
    },
    {
        "anchor": "Density functional theory study of the structural, electronic, and\n  surface reaction properties of bismuth vanady1 oxyhalide BiVO3F: BiVO3F is a promising material used in solar energy conversion systems. Here,\nwe first report the calculated structural, electronic, and surface reaction\nproperties using PBE and hybrid density functionals. We found it is a direct\nband gap semiconductor, and the calculated band gap is consistent with\nexperimental value only using the hybrid density functional with a fraction of\nHartree Fock (HF) exchange {\\alpha}=0.1. The (001) surface is the most stable\nsurface among all the low index (001), (010), and (100) surfaces. There are V\nand Bi sites exposed on (001) surface which can serves as activity sites. That\nis quite different from BiVO4 where only Bi sties can be taken as surface\nreaction sites. The OER intermediates OH* and OOH* prefer to form a bridge\nstructure on both V and Bi sites. This makes the first proton removal step is\nvery easy, but the O-O bond is difficult to form which leads the overpotential\nof OER is very high. Our work plays a guide principle to design the high\nefficiency photocatalysis and photoanodes based on BiVO3F.",
        "positive": "Insulator to metal transition of WO3 epitaxial films induced by\n  electrochemical Li-ion intercalation: We investigated systematic evolutions of structural and electronic properties\nof LixWO3 films, induced by Li-ion electrochemical reactions.\nChronoamperometric Li-ion intercalation could control the amount of Li content\nup to x ~ 0.5. The resistivity abruptly decreased with increasing x and the\nfilms underwent an insulator to metal transition (IMT) within a range of 0.2 <\nx < 0.24, which was consistent with IMT of cubic NaxWO3. The X-ray diffraction\nanalyses revealed the coexistence of tetragonal and cubic phases across IMT,\nsuggesting that the alkaline-ion content was a primary factor for metallic\nconductivity in the ReO3-type WO3 system."
    },
    {
        "anchor": "Lithium Diffusion in Li2X(X=O, S and Se): Ab-initio Simulations and\n  Neutron Inelastic Scattering Measurements: We have performed ab-initio lattice dynamics and molecular dynamics studies\nof Li2X (X=O, S and Se) to understand the ionic conduction in these compounds.\nThe inelastic neutron scattering measurements on Li2O have been performed\nacross its superionic transition temperature of about 1200 K. The experimental\nspectra show significant changes around the superionic transition temperature,\nwhich is attributed to large diffusion of lithium as well as its large\nvibrational amplitude. We have identified a correlation between the chemical\npressure (ionic radius of X atom) and the superionic transition temperature.\nThe simulations are able to provide the ionic diffusion pathways in Li2X.",
        "positive": "Unique opportunity to harness polarization in GaN to override the\n  conventional power electronics figure-of-merits: Owing to the large breakdown electric field, wide bandgap semiconductors such\nas SiC, GaN, Ga2O3 and diamond based power devices are the focus for next\ngeneration power switching applications. The unipolar trade-off relationship\nbetween the area specific-on resistance and breakdown voltage is often employed\nto compare the performance limitation among various materials. The GaN material\nsystem has a unique advantage due to its prominent spontaneous and\npiezoelectric polarization effects in GaN, AlN, InN, AlxInyGaN alloys and\nflexibility in inserting appropriate heterojunctions thus dramatically broaden\nthe device design space."
    },
    {
        "anchor": "Mesoscopic twin boundaries in epitaxial Ni-Mn-Ga films: Twin boundaries play an essential role in the use of magnetic shape memory\nalloy Ni-Mn-Ga as active material. Only if twin boundaries can be moved by an\nexternal magnetic field, high strain values of up to 10 % can be obtained.\nTherefore, understanding the observed twin microstructure of thin films is\ncrucial for future application. We exemplarily present two different\nmicrostructural pattern, type X and type Y microstructure, using the example of\ntwo Ni-Mn-Ga films with similar film thickness and composition. The analysis of\nmicrostructure and structure of the thin films shows that both, type X and type\nY pattern, are formed by mesoscopic 14M twin boundaries. The mesoscopic 14M\ntwin boundaries are either tilted from the substrate surface in case of type X\npattern or they are perpendicular to the surface for type Y pattern. Based on a\nrecently proposed scenario for the nucleation of martensite in austenite, we\ncan trace back the difference in twin boundary orientation to differently\noriented martensitic nuclei.",
        "positive": "Self-assembled nano-columns in Bi2Se3 grown by molecular beam epitaxy: Layered van der Waals (vdW) materials grown by physical vapor deposition\ntechniques are generally assumed to have a weak interaction with the substrate\nduring growth. This leads to films with relatively small domains that are\nusually triangular and a terraced morphology. In this paper, we demonstrate\nthat Bi2Se3, a prototypical vdW material, will form a nano-column morphology\nwhen grown on GaAs(001) substrates. This morphology is explained by a\nrelatively strong film/substrate interaction, long adatom diffusion lengths,\nand a high reactive selenium flux. This discovery paves the way toward growth\nof self-assembled vdW structures even in the absence of strain."
    },
    {
        "anchor": "Cavity mediated coherent coupling of magnetic moments: We demonstrate the long range strong coupling of magnetostatic modes in\nspatially separated ferromagnets mediated by a microwave frequency cavity. Two\nspheres of yttrium iron garnet are embedded in the cavity and their\nmagnetostatic modes probed using a dispersive measurement technique. We find\nthey are strongly coupled to each other even when detuned from the cavity\nmodes. We investigate the dependence of the magnet-magnet coupling on the\ncavity detuning $\\Delta$, and find a $1/\\Delta$ dependence also characteristic\nof cavity-coupled superconducting qubits. Dark states of the coupled\nmagnetostatic modes of the system are observed, and ascribed to mismatches\nbetween the symmetries of the modes and the drive field.",
        "positive": "First principles studies of the Gilbert damping and exchange\n  interactions for half-metallic Heuslers alloys: Heusler alloys have been intensively studied due to the wide variety of\nproperties that they exhibit. One of these properties is of particular interest\nfor technological applications, i.e. the fact that some Heusler alloys are\nhalf-metallic. In the following, a systematic study of the magnetic properties\nof three different Heusler families $\\textrm{Co}_2\\textrm{Mn}\\textrm{Z}$,\n$\\text{Co}_2\\text{Fe}\\text{Z}$ and $\\textrm{Mn}_2\\textrm{V}\\textrm{Z}$ with\n$\\text{Z}=\\left(\\text{Al, Si, Ga, Ge}\\right)$ is performed. A key aspect is the\ndetermination of the Gilbert damping from first principles calculations, with\nspecial focus on the role played by different approximations, the effect that\nsubstitutional disorder and temperature effects. Heisenberg exchange\ninteractions and critical temperature for the alloys are also calculated as\nwell as magnon dispersion relations for representative systems, the\nferromagnetic $\\textrm{Co}_2\\textrm{Fe}\\textrm{Si}$ and the ferrimagnetic\n$\\textrm{Mn}_2\\textrm{V}\\textrm{Al}$. Correlations effects beyond standard\ndensity-functional theory are treated using both the local spin density\napproximation including the Hubbard $U$ and the local spin density\napproximation plus dynamical mean field theory approximation, which allows to\ndetermine if dynamical self-energy corrections can remedy some of the\ninconsistencies which were previously reported for these alloys."
    },
    {
        "anchor": "A Lumped Model for Rotational Modes in Phononic Crystals: We present a lumped model for the rotational modes induced by the rotational\nmotion of individual scatterers in two-dimensional phononic crystals comprised\nof square arrays of solid cylindrical scatterers in solid hosts. The model\nprovides a physical interpretation of the origin of the rotational modes,\nreveals the important role played by the rotational motion in the band\nstructure, and reproduces the dispersion relations. The model increases the\npossibilities of wave manipulation in phononic crystals. In particular,\nexpressions, derived from the model, for eigen-frequencies at high symmetry\npoints unambiguously predict the presence of a new type of Dirac-like cone at\nthe Brillouin center, which is found to be the result of accidental degeneracy\nof the rotational and dipolar modes.",
        "positive": "Image Difference Metrics for High-Resolution Electron Microscopy: Digital image comparison and matching brings many advantages over the\ntraditional subjective human comparison, including speed and reproducibility.\nDespite the existence of an abundance of image difference metrics, most of them\nare not suited for high-resolution transmission electron microscopy (HRTEM)\nimages. In this work we adopt two image difference metrics not widely used for\nTEM images. We compare them to subjective evaluation and to the mean squared\nerror in regards to their behaviour regarding image noise pollution. Finally,\nthe methods are applied to and tested by the task of determining precipitate\nsizes of a model material."
    },
    {
        "anchor": "Strong bulk photovoltaic effect in chiral crystal in the visible\n  spectrum: Structurally chiral materials hosting multifold fermions with large\ntopological number have attracted considerable attention because of their\nnaturally long surface Fermi arcs and bulk quantized circular photogalvanic\neffect (CPGE). Multifold fermions only appear in metallic states, and\ntherefore, most studies so far have only focused on the semimetals in compounds\nwith chiral crystal structures. In this work, we show that the structurally\nchiral topological trivial insulators are also exotic states, which is\ninteresting from the application point of view, owing to their natural\nadvantage to host a large bulk photovoltaic effect in the visible wavelength\nregion. In the last decades, the shift current in the visible wavelength region\nwas limited to be 10 uA/V2 . By scanning the insulators with chiral structure,\nwe found a class of compounds with photoconductivity ranging from 20 to 80\nuA/V2 , which is approximately one order of magnitude larger than that reported\nin other real materials. This work illustrates that the compounds with chiral\nstructure can host both quantum CPGE and a strong shift current in the second\norder optical response. Moreover, this work offers a good platform for the\nstudy of the shift current and its future application by putting the focus on\ninsulator with chiral lattices, so far overlooked in photovoltaic technologies.",
        "positive": "Sonochemical synthesis of large two-dimensional Bi2O2CO3 nanosheets for\n  hydrogen evolution in photocatalytic water splitting: Laterally large (~3 micrometers), atomically-thin two-dimensional (2D)\nBi2O2CO3 nanosheets (2D bismuth oxycarbonate, 2D bismutite) are fabricated via\nsonochemically-assisted template-free synthesis. Key to the synthesis of the\nfreestanding, laterally large 2D Bi2O2CO3 nanosheets from bulk Bi powder is\nchoice of suspension medium, controlled reaction temperatures and several hours\nprocessing time. Lateral sizes of 2D Bi2O2CO3 can be controlled between\nmicrometer-sized nanosheets and tens of nm sized nanoflakes solely based on the\nchoice of suspension medium. The here introduced 2D Bi2O2CO3 nanosheets/-flakes\nare then hybridized by a simple mix-and-match approach with TiO2 nanoparticles\nfor testing in suspension-type photocatalytic hydrogen production via water\nsplitting. This introduces the 2D Bi2O2CO3 with TiO2 as a promising\nnoble-metal-free co-catalyst for photocatalytic hydrogen evolution. Our results\nenrich the fabrication toolbox of emerging 2D pnictogen oxycarbonates towards\nlarge 2D nanosheets and demonstrate the promising potential of 2D Bi2O2CO3 as\nan advantageous (co-)catalyst for hydrogen evolution in photocatalytic water\nsplitting."
    },
    {
        "anchor": "Realization of the electric-field driven \"one-material\"-based magnetic\n  tunnel junction using van der Waals antiferromagnetic MnPX3 (X: S, Se): Presently a lot of efforts are devoted to the investigation of new\ntwo-dimensional magnetic materials, which are considered as promising for the\nrealization of the future electronics and spintronics devices. However, the\nutilization of these materials in different junctions requires complicated\nprocessing that in many cases leads to unwanted parasitic effects influencing\nthe performance of the junctions. Here, we propose the new elegant approach for\nthe realization of the \"one-material\"-based magnetic tunnel junction. The\nseveral layers of 2D van der Waals MnPX3 (X: S, Se), which is insulating\nantiferromagnet in its ground state, are used and the effect of the applied\nexternal electric filed leads to the half-metallic ferromagnetic states for the\noutermost layers of the MnPX3 stack. The rich states diagram of such magnetic\ntunnel junction permits to precisely control its tunneling conductivity. The\nrealized \"one-material\"-based magnetic tunnel junction allows to avoid all\neffects connected with the lattice mismatches and carriers scattering effects\nat the materials interfaces, giving high perspectives for the application of\nsuch systems in electronics and spintronics.",
        "positive": "Band Structure and Quantum Conductance of Nanostructures from\n  Maximally-Localized Wannier Functions: The Case of Functionalized Carbon\n  Nanotubes: We have combined large-scale, $\\Gamma$-point electronic-structure\ncalculations with the maximally-localized Wannier functions approach to\ncalculate efficiently the band structure and the quantum conductance of complex\nsystems containing thousands of atoms while maintaining full first-principles\naccuracy. We have applied this approach to study covalent functionalizations in\nmetallic single-walled carbon nanotubes. We find that the band structure around\nthe Fermi energy is much less dependent on the chemical nature of the ligands\nthan on the $sp^3$ functionalization pattern disrupting the conjugation\nnetwork. Common aryl functionalizations are more stable when paired with\nsaturating hydrogens; even when paired, they still act as strong scattering\ncenters that degrade the ballistic conductance of the nanotubes already at low\ndegrees of coverage."
    },
    {
        "anchor": "Giant spontaneous magnetostriction in MnTe driven by a novel\n  magnetostructural coupling mechanism: We present a comprehensive x-ray scattering study of spontaneous\nmagnetostriction in hexagonal MnTe, an antiferromagnetic semiconductor with a\nNeel temperature of $T_{\\mathrm{N}} = 307$ K. We observe the largest\nspontaneous magnetovolume effect known for an antiferromagnet, reaching a\nvolume contraction of $|\\Delta V/V| > 7 \\times 10^{-3}$. This can be justified\nsemiquantitatively by considering bulk material properties, the spatial\ndependence of the superexchange interaction, and the geometrical arrangement of\nmagnetic moments in MnTe. The highly unusual linear scaling of the\nmagnetovolume effect with the short-range magnetic correlations, beginning in\nthe paramagnetic state well above $T_{\\mathrm{N}}$, points to a novel physical\nmechanism, which we explain in terms of a trilinear coupling of the elastic\nstrain with superposed distinct domains of the antiferromagnetic order\nparameter. This novel mechanism for coupling lattice strain to robust\nshort-range magnetic order casts new light on magnetostrictive phenomena and\nalso provides a template by which the exceptional magnetostrictive properties\nof MnTe might be realized in a wide range of other functional materials.",
        "positive": "Robust intrinsic ferromagnetism in 2D half-metallic material MnAsS$_4$: Two-dimensional (2D) intrinsic half-metallic materials are of great interest\nto explore the exciting physics and applications of nanoscale spintronic\ndevices, but no such materials have been experimentally realized. Using\nfirst-principles calculations based on density-functional theory (DFT), we\npredicted that single-layer MnAsS$_4$ was a 2D intrinsic ferromagnetic (FM)\nhalf-metal. The half-metallic spin gap for single-layer MnAsS$_4$ is about 1.46\neV, and it has a large spin splitting of about 0.49 eV in the conduction band.\nMonte Carlo simulations predicted the Curie temperature (\\emph{T}$_c$) was\nabout 740 K. Moreover, Within the biaxial strain ranging from -5\\% to 5\\%, the\nFM half-metallic properties remain unchanged. Its ground-state with 100\\%\nspin-polarization ratio at Fermi level may be a promising candidate material\nfor 2D spintronic applications."
    },
    {
        "anchor": "Atomistic investigation of the temperature and size dependence of the\n  energy barrier of CoFeB/MgO nanodots: The balance between low power consumption and high efficiency in memory\ndevices is a major limiting factor in the development of new technologies.\nMagnetic random access memories (MRAM) based on CoFeB/MgO magnetic tunnel\njunctions (MTJs) have been proposed as candidates to replace the current\ntechnology due to their non-volatility, high thermal stability and efficient\noperational performance. Understanding the size and temperature dependence of\nthe energy barrier and the nature of the transition mechanism across the\nbarrier between stable configurations is a key issue in the development of\nMRAM. Here we use an atomistic spin model to study the energy barrier to\nreversal in CoFeB/MgO nanodots to determine the effects of size, temperature\nand external field. We find that for practical device sizes in the 10-50 nm\nrange the energy barrier has a complex behaviour characteristic of a transition\nfrom a coherent to domain wall driven reversal process. Such a transition\nregion is not accessible to simple analytical estimates of the energy barrier\npreventing a unique theoretical calculation of the thermal stability. The\natomistic simulations of the energy barrier give good agreement with\nexperimental measurements for similar systems which are at the state of the art\nand can provide guidance to experiments identifying suitable materials and MTJ\nstacks with the desired thermal stability.",
        "positive": "Molecular Gas Adsorption Induced Carrier Transport Studies of Epitaxial\n  Graphene using IR Reflection Spectroscopy: We investigate molecular adsorption doping by electron withdrawing NO2 and\nelectron donating NH3 on epitaxial graphene grown on C-face SiC substrates.\nAmperometric measurements show conductance changes upon introduction of\nmolecular adsorbents on epitaxial graphene. Conductance changes are a trade-off\nbetween carrier concentration and scattering, and manifest at direct current\nand optical frequencies. We therefore investigate changes in the infrared (IR)\nreflection spectra to correlate these two frequency domains, as reflectance\nchanges are due to a change of epitaxial graphene (EG) surface conductance. We\nmatch theory with experimental IR data and extract changes in carrier\nconcentration and scattering due to gas adsorption. Finally, we separate the\nintraband and interband scattering contributions to the electronic transport\nunder gas adsorption. The results indicate that, under gas adsorption, the\ninfluence of interband scattering cannot be neglected, even at DC."
    },
    {
        "anchor": "Metal-insulator transition in the In/Si(111) surface: The metal-insulator transition observed in the In/Si(111)-4x1 reconstruction\nis studied by means of ab initio calculations of a simplified model of the\nsurface. Different surface bands are identified and classified according to\ntheir origin and their response to several structural distortions. We support\nthe, recently proposed [New J. of Phys. 7 (2005) 100], combination of a shear\nand a Peierls distortions as the origin of the metal-insulator transition. Our\nresults also seem to favor an electronic driving force for the transition.",
        "positive": "Electrically Induced Dirac Fermions in Graphene Nanoribbons: Graphene nanoribbons are widely regarded as promising building blocks for\nnext-generation carbon-based devices. A critical issue to their prospective\napplications is whether and to what degree their electronic structure can be\nexternally controlled. Here, we combine simple model Hamiltonians with\nextensive first-principles calculations to investigate the response of armchair\ngraphene nanoribbons to transverse electric fields. Such fields can be achieved\neither upon laterally gating the nanoribbon or incorporating ambipolar chemical\nco-dopants along the edges. We reveal that the field induces a\nsemiconductor-to-semimetal transition, with the semimetallic phase featuring\nzero-energy Dirac fermions that propagate along the armchair edges. The\ntransition occurs at critical fields that scale inversely with the width of the\nnanoribbons. These findings are universal to group-IV honeycomb lattices,\nincluding silicene and germanene nanoribbons, irrespective of the type of edge\ntermination. Overall, our results create new opportunities to electrically\nengineer Dirac fermions in otherwise semiconducting graphene-like nanoribbons."
    },
    {
        "anchor": "Paramagnetism of the Co sublattice in ferromagnetic Zn$_{1-x}$Co$_{x}$O\n  films: Using the spectroscopies based upon x-ray absorption, we have studied the\nstructural and magnetic properties of Zn$_{1-x}$Co$_{x}$O films ($x$ = 0.1 and\n0.25) produced by reactive magnetron sputtering. These films show\nferromagnetism with a Curie temperature $T_{\\mathrm{C}}$ above room temperature\nin bulk magnetization measurements. Our results show that the Co atoms are in a\ndivalent state and in tetrahedral coordination, thus substituting Zn in the\nwurtzite-type structure of ZnO. However, x-ray magnetic circular dichroism at\nthe Co \\textit{L}$_{2,3}$ edges reveals that the Co 3\\textit{d} sublattice is\nparamagnetic at all temperatures down to 2 K, both at the surface and in the\nbulk of the films. The Co 3\\textit{d} magnetic moment at room temperature is\nconsiderably smaller than that inferred from bulk magnetisation measurements,\nsuggesting that the Co 3\\textit{d} electrons are not directly at the origin of\nthe observed ferromagnetism.",
        "positive": "Fingerprints of carbon defects in vibrational spectra of gallium nitride\n  (GaN) consider-ing the isotope effect: This work examines the carbon defects associated with recently reported and\nnovel peaks of infrared (IR) absorption and Raman scattering appearing in GaN\ncrystals at carbon ($^{12}C$) doping in the range of concentrations from\n$3.2*10^{17}$ to $3.5*10^{19} cm^{-3}$. 14 unique vibrational modes of defects\nare observed in GaN samples grown by hydride vapor phase epitaxy (HVPE) and\nthen compared with defect properties predicted from first-principles\ncalculations. The vibrational frequency shift in two $^{13}C$ enriched samples\nrelated to the effect of the isotope mass indicates six distinct configurations\nof the carbon-containing point defects. The effect of the isotope replacement\nis well reproduced by the density functional theory (DFT) calculations.\nSpecific attention is paid to the most pronounced defects, namely tri-carbon\ncomplexes($C_N=C=C_N$) and carbon substituting for nitrogen $C_N$. The position\nof the transition level (+/0) in the bandgap found for $C_N=C=C_N$ defects by\nDFT at 1.1 eV above the valence band maximum, suggest that $(C_N=C=C_N)^+$\nprovides compensation of ${C_N}^-$. $C_N=C=C_N$ defects are observed to be\nprominent, yet have high formation energies in DFT calculations. Regarding\n${C_N}$ defects, it is shown that the host Ga and N atoms are involved in the\ndefect's delocalized vibrations and significantly affect the isotopic frequency\nshift. Much more faint vibrational modes are found from di-atomic carbon-carbon\nand carbon-hydrogen (C-H) complexes. Also, we note changes of vibrational mode\nintensities of $C_N$, $C_N=C=C_N$, C-H, and $C_N-C_i$ defects in the IR\nabsorption spectra upon irradiation in the defect-related UV/visible absorption\nrange. Finally, it is demonstrated that the resonant enhancement of the Raman\nprocess in the range of defect absorption above 2.5 eV enables the detection of\ndefects at carbon doping concentrations as low as $3.2*10^{17} cm^{-3}$."
    },
    {
        "anchor": "Annealing of Au, Ag and Au-Ag alloy nanoparticle arrays on GaAs (100)\n  and (111)B: Part of developing new strategies for fabrications of nanowire structures\ninvolves in many cases the aid of metal nanoparticles (NPs). It is highly\nbeneficial if one can define both diameter and position of the initial NPs and\nmake well-defined nanowire arrays. This sets additional requirement on the NPs\nwith respect to being able to withstand a pre-growth annealing process (i.e.\nde- oxidation of the III-V semiconductor surface) in an epitaxy system.\nRecently, it has been demonstrated that Ag may be an alternative to using Au\nNPs as seeds for particle-seeded nanowire fabrication. This work brings light\nonto the effect of annealing of Au, Ag and Au-Ag alloy NP arrays in two\ncommonly used epitaxial systems, the Molecular Beam Epitaxy (MBE) and the\nMetalorganic Vapor Phase Epitaxy (MOVPE). The NP arrays are fabricated with the\naid of Electron Beam Lithography on GaAs 100 and 111B wafers and the evolution\nof the NPs with respect to shape, size and position on the surfaces are studied\nafter annealing using Scanning Electron Microscopy (SEM). We find that while\nthe Au NP arrays are found to be stable when annealed up to 600 $^{\\circ}$C in\na MOVPE system, a diameter and pitch dependent splitting of the particles are\nseen for annealing in a MBE system. The Ag NP arrays are less stable, with\nsmaller diameters ($\\leq$ 50 nm) dissolving during annealing in both epitaxial\nsystems. In general, the mobility of the NPs is observed to differ between the\ntwo the GaAs 100 and 111B surfaces. While the initial pattern is found be\nintact on the GaAs 111B surface for a particular annealing process and particle\ntype, the increased mobility of the NP on the 100 may influence the initial\npre-defined positions at higher annealing temperatures. The effect of annealing\non Au-Ag alloy NP arrays suggests that these NP can withstand necessary\nannealing conditions for a complete de-oxidation of GaAs surfaces.",
        "positive": "Quasi-Two-Dimensional Extraordinary Hall Effect: Quasi-two-dimensional transport is investigated in a system consisting of one\nferromagnetic layer placed between two insulating layers. Using the mechanism\nof skew-scattering to describe the Extraordinary Hall Effect (EHE) and\ncalculating the conductivity tensor, we compare the quasi- two-dimensional Hall\nresistance with the resistance of a massive sample. In this study a new\nmechanism of EHE (geometric mechanism of EHE) due to non-ideal interfaces and\nvolume defects is also proposed."
    },
    {
        "anchor": "Stacking fault energy of face-centered cubic metals: thermodynamic and\n  ab initio approaches: The formation energy of the interface between face-centered cubic (fcc) and\nhexagonal close packed (hcp) structures is a key parameter in determining the\nstacking fault energy (SFE) of fcc metals and alloys using thermodynamic\ncalculations. Often the contribution of the planar fault energy to the SFE has\nthe same order of magnitude as the bulk part, and thus the lack of a precise\ninformation about it can become the limiting factor in thermodynamic\npredictions. Here, we differentiate between the actual interfacial energy for\nthe coherent fcc(111)/hcp(0001) interface and the \"pseudo-interfacial energy\"\nthat enters the thermodynamic expression for the SFE. Using first-principles\ncalculations, we determine the coherent and pseudo- interfacial energies for\nsix elemental metals (Al, Ni, Cu, Ag, Pt, and Au) and for three paramagnetic\nFe-Cr-Ni alloys. Our results show that the two interfacial energies\nsignificantly differ from each other. We observe a strong chemistry dependence\nof both interfacial energies. The calculated pseudo-interfacial energies for\nthe Fe-Cr-Ni steels agree well with the available literature data.",
        "positive": "Effects of Proton Irradiation on Hole Carrier Transport in\n  Hydrogen-Terminated Diamond Surfaces: In this letter, we report the effects of irradiating hydrogen-terminated\ndiamond surfaces with protons. We study the electrical behavior of the\ntwo-dimensional hole gas that forms on the diamond surface as a result of\nhydrogen-termination. Four diamond samples, two of which were passivated with\nAl2O3 and the other two unpassivated, were irradiated with 2 MeV protons at two\nfluences, 0.5x10^14 and 1.0x10^14 /cm^2. The hole conductivity degraded at a\nhigher proton fluence, which is attributed to the reduction of the mobility\ncaused by enhanced hole scattering. Both passivated and unpassivated samples\nexhibited a reduction in the mobility, which can be explained by charging\neffects of the Al2O3 (for the passivated samples) and degradation of the\nhydrogen-terminated surface (for the unpassivated samples). To our knowledge,\nthis is the first reported data on 2 MeV proton tolerance of\nhydrogen-terminated diamond surfaces."
    },
    {
        "anchor": "Exploration of potential and free energy surfaces of the neutral\n  Be$_4$B$_{8}$ chiral clusters and their stabilities at finite temperatures: The lowest-energy structure, distribution of isomers, and their molecular\nproperties depend significantly on the geometry and temperature. The total\nenergy computations under DFT methodology are typically carried out at zero\ntemperature; thereby, entropic contributions to total energy are neglected,\neven though functional materials work at finite temperature. In the present\nstudy, the probability of occurrence of one particular Be$_4$B$_8$ isomer at\ntemperature T is estimated within the framework of quantum statistical\nmechanics and nanothermodynamics. To locate a list of all possible low-energy\nchiral and achiral structures, an exhaustive and efficient exploration of the\npotential/free energy surface is done by employing a multilevel multistep\nglobal genetic algorithm search coupled to DFT. Moreover, we discuss the\nenergetic ordering of structures computed at the DFT level against single-point\nenergy calculations at the CCSD(T) level of theory. The computed VCD/IR\nspectrum of each isomer is multiplied by their corresponding Boltzmann weight\nat temperature T; then, they are summed together to produce a final Boltzmann\nweighted spectrum. Additionally, we present chemical bonding analysis using the\nAdaptive Natural Density Partitioning method in the chiral putative global\nminimum. The transition state structures and the enantiomer-enantiomer and\nenantiomer-achiral activation energies as a function of temperature, evidence\nthat a change from an endergonic to an exergonic type of reaction occurs at a\ntemperature of 739 K.",
        "positive": "Facile synthesis and step by step enhancement of blue photoluminescence\n  from Ag-doped ZnS quantum dots: Our results pertaining to the step by step enhancement of photoluminescence\n(PL) intensity from ZnS:Ag,Al quantum dots (QDs) are presented. Initially,\nthese QDs were synthesized using a simple co-precipitation technique involving\na surfactant, polyvinylpyrrolidone (PVP), in de-ionised water. It was observed\nthat the blue PL originated from ZnS:Ag,Al QDs was considerably weak and not\nsuitable for any practical display application. Upon UV (365 nm) photolysis,\nthe PL intensity augmented to ~170% and attained a saturation value after ~100\nminutes of exposure. This is attributed to the photo-corrosion mechanism\nexerted by high-flux UV light on ZnS:Ag,Al QDs. Auxiliary enhancement of PL\nintensity to 250% has been evidenced by subjecting the QDs to high temperatures\n(200oC) and pressures (~120 bars) in a sulphur-rich atmosphere, which is due to\nthe improvement in crystallanity of ZnS QDs. The origin of the bright blue PL\nhas been discussed. The results were supported by x-ray phase analysis,\nhigh-resolution electron microscopy and compositional evaluation."
    },
    {
        "anchor": "Stable Ferromagnetism and High Curie Temperature in VGe$_2$N$_4$: The discovery of monolayer MA$_2$Z$_4$ (M = transition metals; A = IVA\nelements; Z = VA elements, Science 369, 2020, 670-674) family has led another\nadvance for facilitating and harnessing magnetism in low-dimensional materials.\nHowever, only Cr and V based MA$_2$N$_4$ compounds exhibit intrinsic magnetism\nyet with unsatisfied magnetic ordering temperature. Herein, we identify a\nstable ferromagnetic number of this family, i.e., VGe$_2$Z$_4$ monolayer, by\nmeans of first-principles calculations. It is found that the magnetic\nconfiguration sustains under both compression and tensile uniaxial in-plane\nstrain, and the former can act as a positive modulator to enhance magnetic\nordering temperature (Tc). Electronic structure calculations reveal a large\nband gap in the spin down channel while band-gapless in the spin up channel, an\nimpressive near-half-metallic character, which is a favorable candidate for\nspintronic device.",
        "positive": "Magnetization Jump in the Magnetization Process of the spin-1/2\n  Heisenberg Antiferromagnet on a Distorted Square-Kagome Lattice: We study the magnetization process of the spin-$1/2$ Heisenberg\nantiferromagnet on a distorted square-kagome lattice by the\nnumerical-diagonalization method. The magnetization jump at one-third of the\nheight of the saturation is examined in detail; we find that the jump becomes\nlarger when a small distortion is switched on and that it is accompanied by an\nabrupt change in lines along microscopic spin directions. Our finite-size\nresults successfully confirm that the magnetization jump in a spin-isotropic\nsystem is a macroscopic jump that survives in the thermodynamic limit and that\nthe changes in spin directions are common to a spin-flop phenomenon observed in\nspin-anisotropic systems."
    },
    {
        "anchor": "Electron-hole asymmetry, Dirac fermions, and quantum magnetoresistance\n  in BaMnBi2: We report two-dimensional quantum transport and Dirac fermions in BaMnBi2\nsingle crystals. BaMnBi2 is a layered bad metal with highly anisotropic\nconductivity and magnetic order below 290 K. Magnetotransport properties,\nnonzero Berry phase, small cyclotronmass, and the first-principles band\nstructure calculations indicate the presence of Dirac fermions in Bi square\nnets. Quantum oscillations in the Hall channel suggest the presence of both\nelectron and hole pockets, whereas Dirac and parabolic states coexist at the\nFermi level.",
        "positive": "A First-Passage Kinetic Monte Carlo Algorithm for Complex\n  Diffusion-Reaction Systems: We develop an asynchronous event-driven First-Passage Kinetic Monte Carlo\n(FPKMC) algorithm for continuous time and space systems involving multiple\ndiffusing and reacting species of spherical particles in two and three\ndimensions. The FPKMC algorithm presented here is based on the method\nintroduced in [Phys. Rev. Lett., 97:230602, 2006] and is implemented in a\nrobust and flexible framework. Unlike standard KMC algorithms such as the\nn-fold algorithm, FPKMC is most efficient at low densities where it replaces\nthe many small hops needed for reactants to find each other with large\nfirst-passage hops sampled from exact time-dependent Green's functions, without\nsacrificing accuracy. We describe in detail the key components of the\nalgorithm, including the event-loop and the sampling of first-passage\nprobability distributions, and demonstrate the accuracy of the new method. We\napply the FPKMC algorithm to the challenging problem of simulation of long-term\nirradiation of metals, relevant to the performance and aging of nuclear\nmaterials in current and future nuclear power plants. The problem of radiation\ndamage spans many decades of time-scales, from picosecond spikes caused by\nprimary cascades, to years of slow damage annealing and microstructure\nevolution. Our implementation of the FPKMC algorithm has been able to simulate\nthe irradiation of a metal sample for durations that are orders of magnitude\nlonger than any previous simulations using the standard Object KMC or more\nrecent asynchronous algorithms."
    },
    {
        "anchor": "Giant Polarization and Abnormal Flexural Deformation in Bent\n  Freestanding Perovskite Oxides: Recent realizations of ultrathin freestanding perovskite oxides offer a\nunique platform to probe novel properties in two-dimensional oxides. Here, we\nobserved a giant flexoelectric response in freestanding BiFeO3 and SrTiO3 in\ntheir bent state arising from strain gradients up to 4x10e7/m, suggesting a\npromising approach for realizing extremely large polarizations. Additionally, a\nsubstantial reversible change in thickness was discovered in bent freestanding\nBiFeO3, which implies an unusual bending-expansion/shrinkage and\nthickness-dependence Poisson's ratios in this ferroelectric membrane that has\nnever been seen before in crystalline materials. Our theoretical modeling\nreveals that this unprecedented flexural deformation within the membrane is\nattributable to a flexoelectricity-piezoelectricity interplay. The finding\nunveils intriguing nanoscale electromechanical properties and provides guidance\nfor their practical applications in flexible nanoelectromechanical systems.",
        "positive": "Review of Best Practice Methods for Determining an Electrode Material's\n  Performance for Ultracapacitors: Ultracapacitors are rapidly being adopted for use for a wide range of\nelectrical energy storage applications. While ultracapacitors are able to\ndeliver high rates of charge and discharge, they are limited in the amount of\nenergy stored. The capacity of ultracapacitors is largely determined by the\nelectrode material and as a result, research to improve the performance of\nelectrode materials has dramatically increased. While test methods for packaged\nultracapacitors are well developed, it is often not feasible for the materials\nscientist to assemble full sized, packaged cells to test electrode materials.\nMethodology to reliably measure a material's performance for ultracapacitor\nelectrode use is not well standardized with the different techniques currently\nbeing used yielding widely varying results. In this manuscript, we review the\nbest practice test methods that accurately predict a materials performance, yet\nare flexible and quick enough to accommodate a wide range of material sample\ntypes and amounts."
    },
    {
        "anchor": "Comprehensive first-principles insights into the physical properties of\n  intermetallic Zr$_3$Ir: a noncentrosymmetric superconductor: We have looked into the structural, mechanical, optoelectronic,\nsuperconducting state and thermophysical aspects of intermetallic compound\nZr$_3$Ir using the density functional theory (DFT). Many of the physical\nproperties, including direction dependent mechanical properties, Vickers\nhardness, optical properties, chemical bonding nature, and charge density\ndistributions, are being investigated for the first time. According to this\nstudy, Zr$_3$Ir exhibits ductile features, high machinability, significant\nmetallic bonding, a low Vickers hardness with low Debye temperature, and a\nmodest level of elastic anisotropy. The mechanical and dynamical stabilities of\nZr$_3$Ir have been confirmed. The metallic nature of Zr$_3$Ir is seen in the\nelectronic band structures with a high electronic energy density of states at\nthe Fermi level. The bonding nature has been explored by the charge density\nmapping and bond population analysis. The tetragonal Zr$_3$Ir shows a\nremarkable electronic stability, as confirmed by the presence of a pseudogap in\nthe electronic energy density of states at the Fermi level between the bonding\nand antibonding states. Optical parameters show very good agreement with the\nelectronic properties. The reflectivity spectra reveal that Zr$_3$Ir is a good\nreflector in the infrared and near-visible regions. Zr$_3$Ir is an excellent\nultra-violet (UV) radiation absorber. High refractive index at visible photon\nenergies indicates that Zr$_3$Ir could be used to improve the visual aspects of\nelectronic displays. All the optical constants exhibit a moderate degree of\nanisotropy. Zr$_3$Ir has a moderate melting point, high damage tolerance, and\nvery low minimum thermal conductivity. The thermomechanical characteristics of\nZr$_3$Ir reveal that it is a potential thermal barrier coating material. The\nsuperconducting state parameters of Zr$_3$Ir are also explored.",
        "positive": "Structural and Dynamical Changes in a Gd-Co Metallic Glass by Cryogenic\n  Rejuvenation: To experimentally clarify the changes in structural and dynamic\nheterogeneities in a metallic glass (MG), Gd65Co35, by rejuvenation with a\ntemperature cycling (cryogenic rejuvenation), high-energy x-ray diffraction\n(HEXRD), anomalous x-ray scattering (AXS), and inelastic x-ray scattering (IXS)\nexperiments were carried out. By a repeated temperature change between liquid\nN2 and room temperatures 40 times, tiny but clear structural changes are\nobserved by HEXRD even in the first neighboring range. Partial structural\ninformation obtained by AXS reveals that slight movements of the Gd and Co\natoms occur in the first- and second-neighboring shells around the central Gd\natom. The concentration inhomogeneity in the nm size drastically increases for\nthe Gd atoms by the temperature cycling, while the other heterogeneities are\nnegligible. A distinct change was detected in a microscopic elastic property by\nIXS: The width of longitudinal acoustic excitation broadens by about 20%,\nindicating an increase of the elastic heterogeneity of this MG by the thermal\ntreatments. These static and dynamic results explicitly clarify the features of\nthe cryogenic rejuvenation effect experimentally."
    },
    {
        "anchor": "Modeling of Circuits with Strongly Temperature Dependent Thermal\n  Conductivities for Cryogenic CMOS: When designing and studying circuits operating at cryogenic temperatures\nunderstanding local heating within the circuits is critical due to the\ntemperature dependence of transistor and noise behavior. We have investigated\nlocal heating effects of a CMOS ring oscillator and current comparator at\nT=4.2K. In two cases, the temperature near the circuit was measured with an\nintegrated thermometer. A lumped element equivalent electrical circuit SPICE\nmodel that accounts for the strongly temperature dependent thermal\nconductivities and special 4.2K heat sinking considerations was developed. The\ntemperature dependence on power is solved numerically with a SPICE package, and\nthe results are within 20% of the measured values for local heating ranging\nfrom <1K to over 100K.",
        "positive": "Atomically Controlled Epitaxial Growth of Single-Crystalline Germanium\n  Films on a Metallic Silicide: We demonstrate high-quality epitaxial germanium (Ge) films on a metallic\nsilicide, Fe3Si, grown directly on a Ge(111) substrate. Using molecular beam\nepitaxy techniques, we can obtain an artificially controlled arrangement of\nsilicon (Si) or iron (Fe) atoms at the surface on Fe3Si(111). The Si-terminated\nFe3Si(111) surface enables us to grow two-dimensional epitaxial Ge films,\nwhereas the Fe-terminated one causes the three-dimensional epitaxial growth of\nGe films. The high-quality Ge grown on the Si-terminated surface has almost no\nstrain, meaning that the Ge films are not grown on the low-temperature-grown Si\nbuffer layer but on the lattice matched metallic Fe3Si. This study will open a\nnew way for vertical-type Ge-channel transistors with metallic source/drain\ncontacts."
    },
    {
        "anchor": "Theory and phase-field simulations on electrical control of spin\n  cycloids in a multiferroic: Cycloidal spin orders are common in multiferroics. One of the prototypical\nexamples is BiFeO3 (BFO) which shows a large polarization and a cycloidal\nantiferromagnetic order at room temperature. Here we employ Landau theory and\nphase-field simulations to analyze the coupled switching dynamics of\npolarization and cycloidal antiferromagnetic orders in BFO. We are able to\nidentify 14 types of transitional spin structures between two cycloids and 9\nelectric-field-induced spin switching paths. We demonstrate the\nelectric-field-induced rotation of wave vectors of the cycloidal spins and\ndiscover 2 types of cycloidal spin switching dynamics: fast local spin flips\nand slow rotation of wave vectors. Also, we construct road maps to achieve the\nswitching between any two spin cycloids through multi-step applications of\nelectric fields. The work provides a theoretical framework for the\nphenomenological description of spin cycloids and a fundamental understanding\nof the switching mechanisms to achieve electrical control of magnetic orders.",
        "positive": "First Principles Study of Carbon Monoxide Adsorption on\n  Zirconia-Supported Copper: We have calculated the adsorption energy of carbon monoxide on a monolayer of\ncopper adsorbed on the (111) face of cubic zirconia. We investigate the\nstructural parameters of three phases of bulk zirconia (cubic, tetragonal, and\nmonoclinic) and find excellent agreement with experiment. We have also analyzed\nthe structural relaxation of both the stoichiometric and reduced (111) surfaces\nof cubic zirconia ($c$-ZrO$_2$). For adsorption of copper on $c$-ZrO$_2$, we\nfind that the preferred binding site is atop the terminal oxygen atom, favored\nby 0.3 eV over other high symmetry sites. We compare CO adsorption on\nzirconia-supported copper to the results of carbon monoxide on copper (100) (S.\nP. Lewis and A. M. Rappe, J. Chem. Phys. {\\bf 110}, 4619,(1999).) and show that\nadsorption on oxide-supported copper is over 0.2 eV more stable than adsorption\non the bare surface."
    },
    {
        "anchor": "Surface reconstruction of tetragonal methylammonium lead triiodide: We present a detailed first-principles analysis of the (001) surface of\nmethylammonium lead triiodide (MAPbI3). With density-functional theory we\ninvestigate the atomic and electronic structure of the tetragonal (I4cm) phase\nof MAPbI3. We analysed surfaces models with MAI- (MAI-T) and\nPbI2-terminations(PbI2-T). For both terminations, we studied the clean-surface\nand a series of surface reconstructions. We find that the clean MAI-T model is\nmore stable than its PbI2-T counterpart. For the MAI\ntermination,reconstructions with added or removed units of nonpolar MAI and\nPbI2 are most stable. The corresponding band structures reveal surface states\noriginating from the conduction band. Despite the presence of such additional\nsurface states, our stable reconstructed surface models do not introduce new\nstates within the band gap.",
        "positive": "Negative Refraction and Subwavelength Lensing in a Polaritonic Crystal: We show that a two-dimensional polaritonic crystal, made of metallic rods\nthat support well defined plasmon oscillations, can act in a narrow frequency\nrange as a medium in which a negative refraction and subwavelength lensing can\noccur. We show that surface modes are excited on the surface of the lens, and\nthat they facilitate restoration of the evanescent waves, which carry the\nsubwavelength image information. We demonstrate that this can occur in the\nvisible frequency range, for a wide range of materials, including silver and\naluminum rods, and carbon nanotubes. This flexibility should allow for an\nexperimental demonstration of this phenomenon in the visible frequency range."
    },
    {
        "anchor": "Unremovable linked nodal structures protected by crystalline symmetries\n  in stacked bilayer graphene with Kekul\u00e9 texture: Linking structure is a new concept characterizing topological semimetals,\nwhich indicates the interweaving of gap-closing nodes at the Fermi energy\n($E_F$) with other nodes below $E_F$. As the number of linked nodes can be\nchanged only via pair-creation or pair-annihilation, a linked node is more\nstable and robust than ordinary nodes without linking. Here we propose a new\ntype of a linked nodal structure between a nodal line (nodal surface) at $E_F$\nwith another nodal line (nodal surface) below $E_F$ in two-dimensional\n(three-dimensional) spinless fermion systems with $\\mathcal{IT}$ symmetry where\n$\\mathcal{I}$ and $\\mathcal{T}$ indicate inversion and time-reversal\nsymmetries, respectively. Because of additional chiral and rotational\nsymmetries, in our system, a double band inversion creates a pair of linked\nnodes carrying the same topological charges, thus the pair are unremovable via\na Lifshiftz transition, which is clearly distinct from the cases of the linked\nnodes reported previously. A realistic tight binding model and effective theory\nare developed for such a linking structure. Also, using density functional\ntheory calculations, we propose a class of materials, composed of stacked\nbilayer graphene with Kekul\\'{e} texture, as a candidate system hosting the new\ntype of the linked nodal structure.",
        "positive": "First-principles computed electronic and magnetic properties of\n  zincblende alkaline-earth pnictides: Employing first-principle electronic structure calculations, we study the\nmagnetic and electronic properties of the XY (X= Mg, Ca, Sr and Y= N, P, As,\nSb) compounds crystallizing in the zincblende structure. The Ca and Sr\nalkaline-earth metal monopnictides are found to be half-metallic with a total\nspin magnetic moment per formula unit of 1.0 $\\mu_B$. In the case of the Mg\nalloys the p-d hybridization effect is much weaker and only MgN is a\nhalf-metal. Electron counting of the bands explains the Slater-Pauling behavior\nexhibited by the total spin magnetic moment. We also study for these alloys the\neffect of deformation taking into account both the cases of hydrostatic\npressure and tetragonalization keeping constant either the in-plane lattice\nparameters or the unit cell volume. Even large degrees of deformation only\nmarginally affect the electronic and magnetic properties of these alloys.\nFinally, we show that this stands also for the rocksalt structure. Our results\nsuggest that alkaline-earth metal monopnictides are promising materials for\nmagnetoelectronic applications."
    },
    {
        "anchor": "Enhancement of low field magnetoresistance at room temperature in\n  La$_{0.67}$Sr$_{0.33}$MnO$_{3}$/Al$_{2}$O$_{3}$ nanocomposite: Magnetotransport properties in a nanocrystalline\nLa$_{0.67}$Sr$_{0.33}$MnO$_{3}$/micron sized Al$_{2}$O$_{3}$ granular composite\nwith different concentrations of Al$_{2}$O$_{3}$ have been studied. The\nresistivity curves in absence of magnetic field and the various transport\nmechanisms which might account for the upturn in resistivity at low\ntemperature, has been discussed. Enhancement of low field magnetoresistance at\nroom temperature with the introduction of Al$_{2}$O$_{3}$ has been observed.",
        "positive": "Pre-notched dog bone small punch specimens for the estimation of\n  fracture properties: In recent years, the pre-notched or pre-cracked small punch test (P-SPT) has\nbeen successfully used to estimate the fracture properties of metallic\nmaterials for cases in which there is not sufficient material to identify these\nproperties from standard tests, such as CT or SENB specimens. The P-SPT\nbasically consists of deforming a pre-notched miniature specimen, whose edges\nare firmly gripped by a die, using a high strength punch. The novelty of this\npaper lies in the estimation of fracture properties using dog-bone-shaped\nspecimens with different confinement levels. With these specimens, three\nconfinement variations have been studied. The results obtained enable the\nestablishment of a variation of fracture properties depending on the level of\nconfinement of each miniature specimen and selection of the most appropriate\nconfinement for this goal."
    },
    {
        "anchor": "Temperature dependent effective third order interatomic force constants\n  from first principles: The temperature dependent effective potential (TDEP) method is generalized\nbeyond pair interactions. The second and third order force constants are\ndetermined consistently from ab initio molecular dynamics simulations at finite\ntemperature. The reliability of the approach is demonstrated by calculations of\nthe Mode Gr\\\"uneisen parameters for Si. We show that the extension of TDEP to\nhigher order allows for an efficient calculation of the phonon life time, in Si\nas well as in $\\epsilon$-FeSi, a system that exhibits anomalous softening with\ntemperature.",
        "positive": "Complex band structure with ultrasoft pseudopotentials: fcc Ni and Ni\n  nanowire: We generalize to magnetic transition metals the approach proposed by Choi and\nIhm for calculating the complex band structure of periodic systems, a key\ningredient for future calculations of conductivity of an open quantum system\nwithin the Landauer-Buttiker theory. The method is implemented with ultrasoft\npseudopotentials and plane wave basis set in a DFT-LSDA ab-initio scheme. As a\nfirst example, we present the complex band structure of bulk fcc Ni (which\nconstitutes the tips of a Ni nanocontact) and monatomic Ni wire (the junction\nbetween two tips). Based on our results, we anticipate some features of the\nspin-dependent conductance in a Ni nanocontact."
    },
    {
        "anchor": "Modification of magnetic and transport properties of manganite layers in\n  Au/La_0.67Sr_0.33MnO_3/SrTiO_3 interfaces: The effect of gold capping on magnetic and transport properties of optimally\ndoped manganite thin films is studied. An extraordinary suppression of\nconductivity and magnetic properties occurs in epitaxial (001)\nLa_0.67Sr_0.33MnO_3 (LSMO) films grown on SrTiO_3 upon deposition of 2 nm of\nAu: in the case of ultrathin films of LSMO (4 nm thick) the resistivity\nincreases by four orders of magnitude while the Curie temperature decreases by\n180 K. Zero-field 55Mn nuclear magnetic resonance reveals a significant\nreduction of ferromagnetic double-exchange mechanism in manganite films upon\nthe gold capping. We find evidence for the formation of a 1.9-nm thick magnetic\n\"dead-layer\" at the Au/LSMO interface, associated with the creation of\ninterfacial non double-exchange insulating phases.",
        "positive": "Reducing the thermal conductivity of carbon nanotubes below the random\n  isotope limit: We find that introducing segmented isotopic disorder patterns may\nconsiderably reduce the thermal conductivity of pristine carbon nanotubes below\nthe uncorrelated disorder value. This is a result of the interplay between\ndifferent length scales in the phonon scattering process. We use ab-initio\natomistic Green's function calculations to quantify the effect of various types\nof segmentation similar to that experimentally produced by coalescence of\nisotope-engineered fullerenes."
    },
    {
        "anchor": "Investigation of the electrostatic potential of a grain boundary in\n  Y-substituted BaZrO3 using inline electron holography: We apply inline electron holography to investigate the electrostatic\npotential across an individual BaZr0.9Y0.1O3 grain boundary. With holography,\nwe measure a grain boundary potential of -1.3 V. Electron energy loss\nspectroscopy analyses indicate that barium vacancies at the grain boundary are\nthe main contributors to the potential well in this sample. Furthermore,\ngeometric phase analysis and density functional theory calculations suggest\nthat reduced atomic density at the grain boundary also contributes to the\nexperimentally measured potential well.",
        "positive": "Modification of electronic structure and thermoelectric properties of\n  hole-doped tungsten dichalcogenides: We present a study on the modification of the electronic structure and\nhole-doping effect for the layered dichalcogenide WSe_2 with a multi-valley\nband structure, where Ta is doped on the W site along with a partial\nsubstitution of Te for its lighter counterpart Se. By means of band-structure\ncalculations and specific-heat measurements, the introduction of Te is\ntheoretically and experimentally found to change the electronic states in\nWSe_2. While in WSe_2 the valence-band maximum is located at the Gamma point,\nthe introduction of Te raises the bands at the K point with respect to the\nGamma point. In addition, thermal-transport measurements reveal a smaller\nthermal conductivity at room temperature of W_1-xTa_xSe_1.6Te_0.4 than reported\nfor W_1-xTa_xSe_2. However, when approaching 900 K, the thermal conductivities\nof both systems converge while the resistivity in W_1-xTa_xSe_1.6Te_0.4 is\nlarger than in W_1-xTa_xSe_2, leading to comparable but slightly smaller values\nof the figure of merit in W_1-xTa_xSe_1.6Te_0.4."
    },
    {
        "anchor": "On the critical character of plasticity in metallic single crystals: Previous acoustic emission (AE) experiments on ice single crystals, as well\nas numerical simulations, called for the possible occurrence of self-organized\ncriticality (SOC) in collective dislocation dynamics during plastic\ndeformation. Here, we report AE experiments on hcp metallic single crystals.\nDislocation avalanches in relation with slip and twinning are identified with\nthe only sources of AE. Both types of processes exhibit a strong intermittent\ncharacter. The AE waveforms of slip and twinning events seem to be different,\nbut from the point of view of the AE event energy distributions, no distinction\nis possible. The distributions always follow a power law, even when multi-slip\nand forest hardening occur. The power law exponent is in perfect agreement with\nthose previously found in ice single crystals. Along with observed time\nclustering and interactions between avalanches, these results are new and\nstrong arguments in favour of a general, SOC-type, framework for crystalline\nplasticity.",
        "positive": "Theoretical study of electron states in Au chains on NiAl(110): We have carried out a density functional study of unoccupied, resonance\nstates in a single Au atom, dimers, a trimer and infinite Au chains on the\nNiAl(110) surface. Two inequivalent orientations of the ad-chains with\nsubstantially different interatomic distances were considered. From the study\nof the evolution of the electron states in an Au chain from being isolated to\nadsorbed, we find that the resonance states derive from the 6$s$ states of the\nAu atoms, which hybridize strongly with the substrate states and develop a\n$p$-like polarization. The calculated resonance states and LDOS images were\nanalyzed in a simple tight-binding, resonance model. This model clarifies (1)\nthe physics of direct and substrate-mediated adatom-adatom interactions and (2)\nthe physics behind the enhancements of the LDOS at the ends of the adatom\nchains, and (3) the physical meaning of the \"particle-in-box\" model used in the\nanalysis of observed resonance states. The calculated effective mass and band\nbottom energy are in good agreement with experimental data obtained from\nscanning tunnelling spectroscopy."
    },
    {
        "anchor": "Structural and Magnetic Study of Metallo-Organic YIG Powder Using\n  2-ethylhexanoate Carboxylate Based Precursors: The crystallization and magnetic behavior of yttrium iron garnet (YIG)\nprepared by metallo-organic decomposition (MOD) method are discussed. The\nchemistry and physics related to synthesis of iron and yttrium carboxylates\nbased on 2-ethylhexanoic acid (2EHA) are studied, since no literature was found\nwhich elucidates synthesis of metallo-organic precursor of YIG in spite of the\nliteratures of doped YIG samples such as Bi-YIG. Typically, the metal\ncarboxylates used in preparation of ceramic oxide materials are\n2-ethylhexanoate (2EH) solvents. Herein, the synthesis, thermal behavior and\nsolubility of yttrium and iron 2EH used in synthesis of YIG powder by MOD are\nreported. The crystallization and magnetic parameters, including saturation\nmagnetization and coercivity of these samples, smoothly change as a function of\nthe annealing temperature. It is observed that high sintering temperature of\n1300 to 1400 {\\deg}C promotes the diffraction peaks of YIG, therefore, we can\nconclude that the formation of YIG in MOD method increases the crystallization\ntemperature. The maximum value of saturation magnetization and minimum value of\ncoercivity and remanence are observed for the sample sintered at 1200{\\deg}C\nwhich are 13.7 emu/g, 10.38 Oe and 1.5 emu/g, respectively. This study cites\nthe drawbacks in chemical synthesis of metallo-organic based YIG production.",
        "positive": "Phonon driven Floquet matter: A resonantly excited coherent phonon leads to a periodic oscillation of the\natomic lattice in a crystal structure bringing the material into a\nnon-equilibrium electronic configuration. Periodically oscillating quantum\nsystems can be understood in terms of Floquet theory and we show these concepts\ncan be applied to coherent lattice vibrations reflecting the underlying\ncoupling mechanism between electrons and bosonic modes. This coupling leads to\ndressed quasi-particles imprinting specific signatures in the spectrum of the\nelectronic structure. Taking graphene as a paradigmatic material we show how\nthe phonon-dressed states display an intricate sideband structure revealing\nelectron-phonon coupling and topological ordering. This work establishes that\nthe recently demonstrated concept of light-induced non-equilibrium Floquet\nphases can also be applied when using coherent phonon modes for the dynamical\ncontrol of material properties. The present results are generic for bosonic\ntime-dependent perturbations and similar phenomena can be observed for plasmon,\nmagnon or exciton driven materials."
    },
    {
        "anchor": "Electronic and magnetic properties of bimetallic L1$_0$ cuboctahedral\n  clusters by means of a fully relativistic density functional based\n  calculations: By means of density functional theory (DFT) and the generalized gradient\napproximation (GGA) we present a structural, electronic and magnetic study of\nFePt, CoPt, FeAu and FePd based L1$_0$ ordered cuboctahedral nanoparticles,\nwith total numbers of atoms, N$_{tot}$ = 13, 55, 147. After a conjugate\ngradient relaxation, the nanoparticles retain their L1$_0$ symmetry, but the\nsmall displacements of the atomic positions tune the electronic and magnetic\nproperties. The value of the total magnetic moment stabilizes as the size\nincreases. We also show that the Magnetic Anisotropy Energy (MAE) depends on\nthe size as well as the position of the Fe-atomic planes in the clusters. We\naddress the influence on the MAE of the surface shape, finding a small in-plane\nMAE for (Fe,Co)$_{24}$Pt$_{31}$ nanoparticles.",
        "positive": "Mechanical Response of Pentadiamond: A DFT and Molecular Dynamics Study: Pentadiamond is a recently proposed new carbon allotrope consisting of a\nnetwork of pentagonal rings where both sp$^2$ and sp$^3$ hybridization are\npresent. In this work we investigated the mechanical and electronic properties,\nas well as, the thermal stability of pentadiamond using DFT and fully atomistic\nreactive molecular dynamics (MD) simulations. We also investigated its\nproperties beyond the elastic regime for three different deformation modes:\ncompression, tensile and shear. The behavior of pentadiamond under compressive\ndeformation showed strong fluctuations in the atomic positions which are\nresponsible for the strain softening at strains beyond the linear regime, which\ncharacterizes the plastic flow. As we increase temperature, as expected,\nYoung's modulus values decrease, but this variation (up to 300 K) is smaller\nthan 10\\% (from 347.5 to 313.6 GPa), but the fracture strain is very sensitive,\nvarying from $\\sim$44\\% at 1K to $\\sim$5\\% at 300K."
    },
    {
        "anchor": "The incorporation site of Er in nanosized CaF 2: The incorporation site of Er dopants inserted at high and low concentration\n(respectively 5 and 0.5 mol %) in nanoparticles of CaF 2 is studied by X-ray\nAbsorption Spectroscopy (XAS) at the Er L III edge. The experimental data are\ncompared with the results of structural modeling based on Density Functional\nTheory (DFT). DFT-based molecular dynamics is also used to simulate complete\ntheoretical EXAFS spectra of the model structures. The results is that Er\nsubstitutes for Ca in the structure and in the low concentration case the\ndopant ions are isolated. At high concentration the rare earth ions cluster\ntogether binding Ca vacancies.",
        "positive": "Dissecting functional degradation in NiTi shape-memory-alloys containing\n  amorphous regions via atomistic simulations: Molecular dynamics simulations are performed to provide a detailed\nunderstanding of the functional degradation of shape memory alloys at small\nscale. The origin of the experimentally reported accumulation of plastic\ndeformation and the anomalous sudden increase of the residual strain under\ncyclic mechanical loading are explained by detailed insights into the relevant\natomic scale processes. Our work reveals that the mechanical response of\nshape-memory-alloy pillars under cyclic compression is significantly influenced\nby the presence of an amorphous-like surface region as experimentally induced\nby focused ion beam milling. The main factor responsible for the observed\ndegradation of superelasticity under cyclic loading is the accumulated plastic\ndeformation and the resultant retained martensite originating from a synergetic\ncontribution of the amorphous and crystalline shape-memory-alloy regions. We\nshow that the reported sudden diminishment of the stress plateaus and\nhysteresis under cyclic loading is caused by the increased stability of the\nmartensite phase due to the presence of the amorphous phase. Based on the\nidentified mechanism responsible for the degradation, we validate reported\nmethods of recovering the superelasticity and propose a new method to prohibit\nthe synergetic contribution of the amorphous and crystalline regions, such as\nto achieve a sustainable operation of shape memory alloys at small scale."
    },
    {
        "anchor": "Origin of negative anomalous Nernst thermopower in Mn-Ga ordered alloys: The negative sign of the anomalous Nernst thermopower ($S_\\text{ANE}$)\nobserved in Mn-Ga ordered alloys is an attractive property for thermoelectric\napplications exploiting the anomalous Nernst effect (ANE); however, its origin\nhas not been clarified. In this study, to gain insight into the negative\n$S_\\text{ANE}$, we prepared epitaxial thin films of Mn$_{x}$Ga$_{100-x}$ with\n$x$ ranging from 56.2 to 71.7, and systematically investigated the structural,\nmagnetic, and transport properties including the anomalous Hall effect (AHE)\nand the ANE. The measured $S_\\text{ANE}$ is negative for all samples and shows\nclose to one order of magnitude difference among different compositions.\nTogether with the measured transport properties, we were able to separate the\ntwo different contributions of the ANE, i.e., one originating from the\ntransverse thermoelectric coefficient ($\\alpha_{xy}$), and the other one\noriginating from the AHE acting on the longitudinal carrier flow induced by the\nSeebeck effect. Both contributions are found to be negative for all samples,\nwhile the experimentally obtained negative $\\alpha_{xy}$ exhibits a monotonic\nincrease towards zero with increasing $x$, which is consistent with the\ntendency indicated by first-principles calculations. Our results show that the\nlarge difference in the negative $S_\\text{ANE}$ is mostly attributed to\n$\\alpha_{xy}$, and thus shed light on further enhancement of the ANE in\nMn-based ordered alloys.",
        "positive": "Formation of cBN nanocrystals by He+ implantations of hBN: The structural modifications of polycrystalline hexagonal boron nitride\nimplanted with He+ ion beams at energies between 200 keV and 1.2 MeV to\nfluences of 1.0 \\times 1017 ions \\cdot cm-2 were investigated using micro-Raman\nspectroscopy. The measured Raman spectra show evidence of implantation-induced\nstructural transformations from the hexagonal phase to nanocrystalline cubic\nboron nitride, rhombohedral boron nitride and amorphous boron nitride phases.\nThe first-order Longitudinal-Optical cBN phonon was observed to be downshifted\nand asymmetrically broadened and this was explained using the spatial\ncorrelation model coupled with the high ion implantation-induced defect\ndensity."
    },
    {
        "anchor": "Exciton-polaron spectral structures in two dimensional hybrid\n  lead-halide perovskites: Owing to both electronic and dielectric confinement effects, two-dimensional\norganic-inorganic hybrid perovskites sustain strongly bound excitons at room\ntemperature. Here, we demonstrate that there are non-negligible contributions\nto the excitonic correlations that are specific to the lattice structure and\nits polar fluctuations, both of which are controlled via the chemical nature of\nthe organic counter-cation. We present a phenomenological, yet quantitative\nframework to simulate excitonic absorption lineshapes in single-layer\norganic-inorganic hybrid perovskites, based on the two-dimensional Wannier\nformalism. We include four distinct excitonic states separated by\n$35\\pm5$\\,meV, and additional vibronic progressions. Intriguingly, the\nassociated Huang-Rhys factors and the relevant phonon energies show substantial\nvariation with temperature and the nature of the organic cation. This points to\nthe hybrid nature of the lineshape, with a form well described by a Wannier\nformalism, but with signatures of strong coupling to localized vibrations, and\npolaronic effects perceived through excitonic correlations. Our work highlights\nthe complexity of excitonic properties in this class of nanostructured\nmaterials.",
        "positive": "Mastering disorder in a first-order transition by ion irradiation: The effect of ion bombardment on MnAs single crystalline thin films is\nstudied. The role of elastic collisions between ions and atoms of the material\nis singled-out as the main process responsible for modifying the properties of\nthe material. Thermal hysteresis suppression, and the loss of sharpness of the\nmagneto-structural phase transition are studied as a function of different\nirradiation conditions. While the latter is shown to be associated with the ion\ninduced disorder at the scale of the transition correlation length, the former\nis related to the coupling between disorder and the large-scale elastic field\nassociated with the phase coexistence pattern."
    },
    {
        "anchor": "New Research Trends in Electrically Tunable 2D van der Waals Magnetic\n  Materials: The recent discovery of two-dimensional (2D) van der Waals (vdW) magnetic\nmaterials has provided new, unprecedented opportunities for both fundamental\nscience and technological applications. Unlike three-dimensional (3D) magnetic\nsystems, the electric manipulation of vdW magnetism (e.g., magnetization state,\nmagnetic anisotropy, magnetic ordering temperature) down to the monolayer limit\nat ambient conditions enables high efficiency operation and low energy\nconsumption, which has the potential to revolutionize the fields of\nspintronics, spin-caloritronics, and valleytronics. This article provides an\nin-depth analysis of the recent progress, emerging opportunities, and technical\nchallenges in the electric manipulation of magnetic functionalities of a wide\nvariety of 2D vdW magnetic systems ranging from metals to semiconductors and\nheterostructures. The state-of-the-art understanding of the mechanisms behind\nthe electric modulation of magnetism in these 2D vdW magnetic systems will\ndrive future research towards novel applications in spintronics,\nspin-caloritronics, valleytronics, and quantum computation.",
        "positive": "Hopping magneto-transport via nonzero orbital momentum states and\n  organic magnetoresistance: In hopping magnetoresistance of doped insulators, an applied magnetic field\nshrinks the electron (hole) s-wave function of a donor or an acceptor and this\nreduces the overlap between hopping sites resulting in the positive\nmagnetoresistance quadratic in a weak magnetic field, B. We extend the theory\nof hopping magnetoresistance to states with nonzero orbital momenta. Different\nfrom s-states, a weak magnetic field expands the electron (hole) wave functions\nwith positive magnetic quantum numbers, m > 0, and shrinks the states with\nnegative m in a wide region outside the point defect. This together with a\nmagnetic-field dependence of injection/ionization rates results in a negative\nweak-field magnetoresistance, which is linear in B when the orbital degeneracy\nis lifted. The theory provides a possible explanation of a large low-field\nmagnetoresistance in disordered pi-conjugated organic materials (OMAR)."
    },
    {
        "anchor": "Induced ferroelectric phases in TbMn_2O_5: The magnetostructural transitions and magnetoelectric effects reported in\nTbMn2O5 are described theoretically and shown to correspond to two essentially\ndifferent mechanisms for the induced ferroelectricity. The incommensurate and\ncommensurate phases observed between 38 and 24 K exhibit a hybrid pseudoproper\nferroelectric nature resulting from an effective bilinear coupling of the\npolarization with the antiferromagnetic order parameter. This explains the high\nsensitivity of the dielectric properties of the material under applied magnetic\nfield. Below 24 K the incommensurate phase shows a standard improper\nferroelectric character induced by the coupling of two distinct magnetic order\nparameters. The complex dielectric behavior observed in the material reflects\nthe crossover from one to the other transition regime. The temperature\ndependences of the pertinent physical quantities are worked out, and previous\ntheoretical models are discussed.",
        "positive": "Shear induced crystallization of an amorphous system: The influence of a stationary shear flow on the crystallization in a glassy\nsystem is studied by means of molecular dynamics simulations and subsequent\ncluster analysis. The results reveal two opposite effects of the shear flow on\nthe processes of topological ordering in the system. Shear promotes the\nformation of separated crystallites and suppresses the appearance of the large\nclusters. The shear-induced ordering proceeds in two stages, where the first\nstage is related mainly with the growth of crystallites, whereas the second\nstage is due to an adjustment of the created clusters and a progressive\nalignment of their lattice directions. The influence of strain and shear rate\non the crystallization is also investigated. In particular, we find two\nplausible phenomenological relations between the shear rate and the\ncharacteristic time scale needed for ordering of the amorphous system under\nshear."
    },
    {
        "anchor": "Ti-enhanced kinetics of hydrogen absorption and desorption on NaAlH4\n  surfaces: We report a first-principles study of the energetics of hydrogen absorption\nand desorption (i.e. H-vacancy formation) on pure and Ti-doped sodium alanate\n(NaAlH4) surfaces. We find that the Ti atom facilitates the dissociation of H2\nmolecules as well as the adsorption of H atoms. In addition, the dopant makes\nit energetically more favorable to creat H vacancies by saturating Al dangling\nbonds. Interestingly, our results show that the Ti dopant brings close in\nenergy all the steps presumably involved in the absorption and desorption of\nhydrogen, thus facilitating both and enhancing the reaction kinetics of the\nalanates. We also discuss the possibility of using other light transition\nmetals (Sc, V, and Cr) as dopants.",
        "positive": "New High-Pressure Phases of MoSe$_2$ and MoTe$_2$: Three Mo-based transition metal dichalcogenides MoS$_2$, MoSe$_2$ and\nMoTe$_2$ share at ambient conditions the same structure 2H$_c$, consisting of\nlayers where Mo atoms are surrounded by six chalcogen atoms in trigonal prism\ncoordination. The knowledge of their high-pressure behaviour is, however,\nlimited, particularly in case of MoSe$_2$ and MoTe$_2$. The latter materials do\nnot undergo a layer-sliding transition 2H$_c$ $\\rightarrow$ 2H$_a$ known in\nMoS$_2$ and currently no other stable phase besides 2H$_c$ is known in these\nsystems at room temperature. Employing evolutionary crystal structure\nprediction in combination with \\textit{ab initio} calculations we study the\nzero-temperature phase diagram of both materials up to Mbar pressures. We find\na tetragonal phase with space group \\textit{P4/mmm}, previously predicted in\nMoS$_2$, to become stable in MoSe$_2$ at 118 GPa. In MoTe$_2$ we predict at 50\nGPa a transition to a new layered tetragonal structure with space group\n\\textit{I4/mmm}, similar to CaC$_2$, where Mo atoms are surrounded by eight Te\natoms. The phase is metallic already at the transition pressure and becomes a\ngood metal beyond 1 Mbar. We discuss chemical trends in the family of Mo-based\ntransition metal dichalcogenides and suggest that MoTe$_2$ likely offers the\neasiest route towards the post-2H phases."
    },
    {
        "anchor": "The Structure and Local Variations of the Graphene Moir\u00e9 on Ir(111): We have studied the incommensurate moir\\'e structure of epitaxial graphene\ngrown on iridium(111) by dynamic low energy electron diffraction [LEED-I(V)]\nand non-contact atomic force microscopy (AFM) with a CO terminated tip. Our\nLEED-I(V) results yield the average positions of all the atoms in the surface\nunit cell and are in qualitative agreement with the structure obtained from\ndensity functional theory (DFT). The AFM experiments reveal local variations of\nthe moir\\'e structure: the corrugation varies smoothly over several moir\\'e\nunit cells between 42 and 56 pm. We attribute these variations to the varying\nregistry between the moir\\'e symmetry sites and the underlying substrate. We\nalso observe isolated outliers, where the moir\\'e top sites can be offset by an\nadditional 10 pm. This study demonstrates that AFM imaging can be used to\ndirectly yield the local surface topography with pm accuracy even on\nincommensurate 2D structures with varying chemical reactivity.",
        "positive": "Instability of two dimensional graphene: Breaking sp2 bonds with soft\n  X-rays: We study the stability of various kinds of graphene samples under soft X-ray\nirradiation. Our results show that in single layer exfoliated graphene (a\ncloser analogue to two dimensional material), the in-plane carbon-carbon bonds\nare unstable under X-ray irradiation, resulting in nanocrystalline structures.\nAs the interaction along the third dimension increases by increasing the number\nof graphene layers or through the interaction with the substrate (epitaxial\ngraphene), the effect of X-ray irradiation decreases and eventually becomes\nnegligible for graphite and epitaxial graphene. Our results demonstrate the\nimportance of the interaction along the third dimension in stabilizing the long\nrange in-plane carbon-carbon bonding, and suggest the possibility of using\nX-ray to pattern graphene nanostructures in exfoliated graphene."
    },
    {
        "anchor": "Exchange scaling of ultrafast angular momentum transfer in 4$\\it{f}$\n  antiferromagnets: Ultrafast manipulation of the magnetic state of matter bears great potential\nfor future information technologies. While demagnetisation in ferromagnets is\ngoverned by dissipation of angular momentum, materials with multiple spin\nsublattices, e.g. antiferromagnets, can allow direct angular momentum transfer\nbetween opposing spins, promising faster functionality. In lanthanides,\n4$\\it{f}$ magnetic exchange is mediated indirectly through the conduction\nelectrons (the Ruderman-Kittel-Kasuya-Yosida interaction, RKKY), and the effect\nof such conditions on direct spin transfer processes is largely unexplored.\nHere, we investigate ultrafast magnetization dynamics in 4f antiferromagnets,\nand systematically vary the 4$\\it{f}$ occupation, thereby altering the\nmagnitude of RKKY. By combining time-resolved soft x-ray diffraction with\nab-initio calculations, we find that the rate of direct transfer between\nopposing moments is directly determined by the magnitude of RKKY. Given the\nhigh sensitivity of RKKY to the conduction electrons, our results offer a novel\napproach for fine-tuning the speed of magnetic devices.",
        "positive": "Gapped Dirac cones and spin texture in thin film topological insulator: The protected surface states of topological insulators (TIs) form gapless\nDirac cones corresponding non-degenerate eigenstates with helical spin\npolarisation. The presence of a warping term deforms the isotropic cone of the\nmost simple model into snowflake Fermi surfaces as in Bi2Se3 and Bi2Te3. Their\nfeatures have been identified in STM quasiparticle interference (QPI)\nexperiments on isolated surfaces. Here we investigate the QPI spectrum for the\nTI thin-film geometry with finite tunnelling between the surface states. This\nleads to a dramatic change of spectrum due to gapping and a change in spin\ntexture that should leave distinct signatures in the QPI pattern. We consider\nboth normal and magnetic exchange scattering from the surface impurities and\nobtain the scattering t-matrix in Born approximation as well as the general\nclosed solution. We show the expected systematic variation of QPI snowflake\nintensity features by varying film thickness and study, in particular, the\ninfluence on backscattering processes. We predict the variation of the QPI\nspectrum for Bi2Se3 thin films using the observed gap dependence from ARPES\nresults."
    },
    {
        "anchor": "Defects controlled hole doping and multi-valley transport in SnSe single\n  crystals: SnSe is a promising thermoelectric material with record-breaking figure of\nmerit, \\textit{i.e., ZT}. As a semiconductor, optimal electrical dosage is the\nkey challenge to maximize \\textit{ZT} in SnSe. However, to date a comprehensive\nunderstanding of the electronic structure and most critically, the self-hole\ndoping mechanism in SnSe is still absent. Here, we report the highly\nanisotropic electronic structure of SnSe investigated by both angle-resolved\nphotoemission spectroscopy and quantum transport, in which a unique\n\"\\textit{pudding-mold}\" shaped valence band with quasi-linear energy dispersion\nis revealed. We prove that the electrical doping in SnSe is extrinsically\ncontrolled by the formation of SnSe$_{2}$ micro-domains induced by local phase\nsegregation. Using different growth methods and conditions, we have achieved\nwide tuning of hole doping in SnSe, ranging from intrinsic semiconducting\nbehaviour to typical metal with carrier density of $1.23\\times 10^{18}$\ncm$^{-3}$ at room temperature. The resulting multi-valley transport in $p$-SnSe\nis characterized by non-saturating weak localization along the armchair axis,\ndue to strong intervalley scattering enhanced by in-plane ferroelectric dipole\nfield of the puckering lattice. Strikingly, quantum oscillations of\nmagnetoresistance reveal three-dimensional electronic structure with unusual\ninterlayer coupling strength in $p$-SnSe, which is correlated to the\ninterweaving of SnSe individual layers by unique point dislocation defects. Our\nresults suggest that defect engineering may provide versatile routes in\nimproving the thermoelectric performance of the SnSe family.",
        "positive": "Avalanches and rate effects in strain-controlled discrete dislocation\n  plasticity of Al single crystals: Three-dimensional discrete dislocation dynamics simulations are used to study\nstrain-controlled plastic deformation of face-centered cubic aluminium single\ncrystals. After describing the rate and size dependence of the average\nstress-strain curves, we study the power-law distributed strain bursts and the\naverage avalanche shapes, and find a universal power-law exponent $\\tau \\approx\n1.0$ for all imposed strain rates and system sizes, characterizing both the\nevent sizes and their durations. We discuss the dependence of our results on\nloading rate and compare these with previous studies of strain-controlled\ntwo-dimensional systems of discrete dislocations as well as of quasistatic\nstress-controlled loading of aluminium single crystals."
    },
    {
        "anchor": "Crystal structures of dodecaborides: complexity in simplicity: Analysis of the intriguing physical properties of the dodecaborides,\n$R$B$_{12}$, requires accurate data on their crystal structure. We show that a\nsimple cubic model fits well with the atomic positions in the unit cell but\ncannot explain the observed anisotropy in the physical properties. The\ncooperative Jahn-Teller (JT) effect slightly violates the ideal metric of the\ncubic lattice and the symmetry of the electron density distribution in the\nlattice interstices. Theoretical models of the JT distortions of the boron\nframework are presented. Their correspondence to the electron-density\ndistribution on the maps of Fourier syntheses obtained using x-ray data and\nexplaining the previously observed anisotropy of conductive properties is\ndemonstrated. The effect of boron isotope composition on the character of the\nlattice distortions is shown. We also discuss the application of the Einstein\nmodel for cations and the Debye model for the boron atoms to describe the\ndynamics of the crystal lattice.",
        "positive": "Simultaneous Grain Boundary Motion, Grain Rotation, and Sliding in a\n  Tricrystal: Grain rotation and grain boundary (GB) sliding are two important mechanisms\nfor grain coarsening and plastic deformation in nanocrystalline materials. They\nare in general coupled with GB migration and the resulting dynamics, driven by\ncapillary and external stress, is significantly affected by the presence of\njunctions. Our aim is to develop and apply a novel continuum theory of\nincoherent interfaces with junctions to derive the kinetic relations for the\ncoupled motion in a tricrystalline arrangement. The considered tricrystal\nconsists of a columnar grain embedded at the center of a non-planar GB of a\nmuch larger bicrystal made of two rectangular grains. We examine the shape\nevolution of the embedded grain numerically using a finite difference scheme\nwhile emphasizing the role of coupled motion as well as junction mobility and\nexternal stress. The shape accommodation at the GB, necessary to maintain\ncoherency, is achieved by allowing for GB diffusion along the boundary."
    },
    {
        "anchor": "The Structural, Energetic and Electronic Properties of Doped Carbon\n  Nanotubes by Encapsulation of MCp2 (M=Fe, Co, Ni): a Theoretical\n  Investigation: Metallocenes can be encapsulated inside the carbon nanotubes. The structural,\nenergetic and electronic properties of organometallic MCp2@SWCNT are obtained\nfrom DFT method. We verify that such encapsulation is noncovalent\nfunctionalization, and examined binding energies and charge transfers of\nMCp2@(16,0)SWCNT systems. Consistent with recent experimental findings, the\noptimal distance between FeCp2 center and near tube-wall is 4.7 (5.1) {\\AA} for\nthe configuration where MCp2's five-fold axis is parallel (vertical) to\nnanotube axis, while the minimal diameter is 9.4 (10.2) {\\AA} to exothermically\nencapsulate FeCp2 molecules. Finally we clarify the doping effects near the\nbandgap by encapsulations of CoCp2 and NiCp2.",
        "positive": "n-Type diamond synthesized with tert-butylphosphine for long spin\n  coherence times of perfectly aligned NV centers: The longest spin coherence times for nitrogen-vacancy (NV) centers at room\ntemperature have been achieved in phosphorus-doped n-type diamond. However,\ndifficulty controlling impurity incorporation and the utilization of highly\ntoxic phosphine gas in the chemical vapor deposition (CVD) technique pose\nproblems for the growth of n-type diamond. In the present study, n-type diamond\nsamples were synthesized by CVD using tert-butylphosphine, which is much less\ntoxic than phosphine. The unintentional incorporation of nitrogen was found to\nbe suppressed by incrementally increasing the gas flow rates of H2 and CH$_4$.\nHall measurements confirmed n-type conduction in three measured samples\nprepared under different growth conditions. The highest measured Hall mobility\nat room temperature was 422 cm$^2$/(Vs). In the sample with the lowest nitrogen\nconcentration, the spin coherence time ($T_2$) increased to 1.62 $\\pm$ 0.10 ms.\nOptically detected magnetic resonance spectra indicated that all of the\nmeasured NV centers were aligned along the [111] direction. This study provides\nappropriate CVD conditions for growing phosphorus-doped n-type diamond with\nperfectly aligned NV centers exhibiting long spin coherence times, which is\nimportant for the production of quantum diamond devices."
    },
    {
        "anchor": "Simple iterative construction of the optimized effective potential for\n  orbital functionals, including exact exchange: For exchange-correlation functionals that depend explicitly on the Kohn-Sham\norbitals, the potential $V_{\\mathrm{xc}\\sigma}(\\re)$ must be obtained as the\nsolution of the optimized effective potential (OEP) integral equation. This is\nvery demanding and has limited the use of orbital functionals like exact\nexchange. We demonstrate that the OEP can be obtained iteratively by solving a\nsystem of partial differential equations instead of an integral equation. This\namounts to calculating the orbital shifts that exactify the Krieger-Li-Iafrate\n(KLI) approximation. Unoccupied orbitals do not need to be calculated. Accuracy\nand efficiency of the method are shown for atoms and clusters using the exact\nexchange energy. Counter-intuitive asymptotic limits of the exact OEP, not\naccessible from previous constructions, are presented.",
        "positive": "Electronic structure of (Ga,Mn)As revisited: an alternative view on the\n  \"Battle of the bands\": New detailed angle-resolved photoemission data are presented, revealing the\nexistence of an Mn-induced state that extends into the band gap of GaAs. In\nsharp contrast to recent reports we observe that the state is highly\ndispersive. Spin resolved photoemission shows that the band is spin polarized\neven at room temperature. The results are not consistent with any of the\ncurrently discussed band models for ferromagnetism."
    },
    {
        "anchor": "Skyrmion lattice in centrosymmetric magnets with local\n  Dzyaloshinsky-Moriya interaction: It is common that the local inversion symmetry in crystals is broken, even\nthough the whole crystal has global inversion symmetry. This local inversion\nsymmetry breaking allows for a local Dzyaloshinsky-Moriya interaction (DMI) in\nmagnetic crystals. Here we show that the local DMI can stabilize a skyrmion as\na metastable excitation or as a skyrmion crystal in equilibrium. We consider\ncrystal structure with layered structure as an example, where local inversion\nis violated in each layer but a global inversion center exists in the middle of\nthe two layers. These skyrmions come in pairs that are related by the inversion\nsymmetry. The two skyrmions with opposite helicity in a pair form a bound\nstate. We study the properties of a skyrmion pair in the ferromagnetic\nbackground and determine the equilibrium phase diagram, where a robust lattice\nof skyrmion pairs is stabilized. Our results point to a new direction to search\nfor the skyrmion lattice in centrosymmetric magnets.",
        "positive": "Polarization and Structure of Small Clusters: In this paper we report the structure of the Li4Ge4 cluster as a function of\ncharge transfer and polarizability. We find that for small charge transfer (Q <\n0.5) this cluster has the expected cubic structure: a Ge4 tetrahedron with a Li\nion attached at large distance to each face. With increasing charge transfer Q\n> 0.5 the structure of Li4Ge4 changes: for relative small polarizability of the\nGe ion the Ge4 breaks up into two Ge2 pairs separated by the four Li. For\nlarger polarizability there are three possibilities: 1) for full charge\ntransfer the Li ions break up the Ge subcluster into four separated ions; 2)\nfor smaller values of the charge transfer we still have the structure with two\nGe2 pairs and 3) for intermediate values of, charge transfer the Ge sublattice\nforms a structure with two opposite bonds of the Ge4 tetrahedron cluster\nbroken. These are the only stable geometries found. For large Ge polarizability\nwe find that all structures become unstable: the size of the induced dipole\nmoment becomes larger than the diameter of Ge. Based on this phase diagram of\nLi4Ge4 we discuss the structure of other A4M4 alkali(= A)--tetralide (= M) (=\ngroup 14) clusters, and related solid state structures"
    },
    {
        "anchor": "Effect of Non-stoichiometry on Magnetocaloric Properties of HoB2\n  Gas-Atomized Particles: We fabricate gas-atomized particles by inductively melting electrode rods of\nHoB2-x (x = -0.3, 0, 0.3, and 1.0) and investigate the effect of\nnon-stoichiometry on the phase fraction, microstructure, and physical\nproperties. Shifting the stoichiometric ratio of the electrode rod to the B\n(Ho)-rich side increases HoB4 (Ho) phase in the resulting atomized particles.\nEven if the atomized particles contain 15-20 weight percent (wt.%) of the\nimpurity phase, the influence of which on the physical properties is less\nsevere: the maximum value of the magnetic entropy change is only reduced by 10%\ncompared to HoB2.0 particles. We further find that the ductile Ho phase exists\nso as to fill the space between the brittle HoB2 phases in the atomized\nparticles, which may be beneficial to the mechanical properties of the\nparticles. Our findings suggest that it would be better to use the Ho-rich\nelectrode rods than the stoichiometric ones to produce HoB2-x particles with\nmore suitable properties as a magnetic refrigerant for magnetic refrigeration\nsystems.",
        "positive": "Tunable Wave Propagation Bandgap Via Stretching kirigami Sheets: This study examines the Braggs bandgap and its mechanical tuning in a\nstretch-buckled kirigami sheet with \"zig-zag\" distributed parallel cuts. When\nstretched beyond a critical threshold, the kirigami buckles out-of-plane and\ngenerates a 3D periodic architecture. Our theoretical calculation, numerical\nsimulation, and experiments confirm the transverse elastic wave propagation\nbandgaps and their correlation to stretching. This result opens an avenue of\nusing kirigami as a simple and effective approach for creating and adapting\nperiodicity for wave propagation control."
    },
    {
        "anchor": "Acoustic Lens Design: A survey of acoustic devices for focusing airborne sound is presented. We\nintroduce a new approach to design high quality acoustic lenses based on arrays\nof cylindrical rigid scatterers in air. A population based stochastic search\nalgorithm is used in conjunction with the multiple scattering theory to\noptimize a cluster of cylinders that focuses the sound in a prefixed focal\npoint. Various lenses of different sized clusters, for different frequencies\nand with different focal lengths are presented. In general three focusing\nphenomena are remarked, focusing due to refraction, diffraction and focusing\ndue to multiple scattering. The dependency on the frequency of the incident\nsound and the focal distance is analyzed indicating that higher frequencies and\nsmaller focal distances favour larger amplifications in thin lenses based on\nmultiple scattering. Furthermore, the robustness of a designed acoustic lens is\nstudied, examining the focusing effect against errors in the cylinders'\npositions and their radius.",
        "positive": "Magnetic phase diagram, magnetotransport and inverse magnetocaloric\n  effect in the noncollinear antiferromagnet Mn$_5$Si$_3$: The antiferromagnet Mn$_5$Si$_3$ has recently attracted attention because a\nnoncollinear spin arrangement has been shown to produce a topological anomalous\nHall effect and an inverse magnetocaloric effect. Here we synthesize single\ncrystals of Mn$_5$Si$_3$ using flux growth. We determine the phase diagram\nthrough magnetization and measure the magnetoresistance and the Hall effect. We\nfind the collinear and noncollinear antiferromagnetic phases at low\ntemperatures and, in addition, a third magnetic phase, in between the two\nantiferromagnetic phases which has ferromagnetic character. The latter magnetic\nphase might be caused by strain produced by Cu inclusions that lead to quenched\nfluctuations of the mixed character magnetic ordering in this compound."
    },
    {
        "anchor": "Role of transverse displacements for a quantized-velocity state of the\n  lubricant: Within the idealized scheme of a 1-dimensional Frenkel-Kontorova-like model,\na special \"quantized\" sliding state was found for a solid lubricant confined\nbetween two periodic layers [PRL 97, 056101 (2006)]. This state, characterized\nby a nontrivial geometrically fixed ratio of the mean lubricant drift velocity\n<v_cm> and the externally imposed translational velocity v_ext, was understood\nas due to the kinks (or solitons), formed by the lubricant due to\nincommensuracy with one of the substrates, pinning to the other sliding\nsubstrate. A quantized sliding state of the same nature is demonstrated here\nfor a substantially less idealized 2-dimensional model, where atoms are allowed\nto move perpendicularly to the sliding direction and interact via Lennard-Jones\npotentials. Clear evidence for quantized sliding at finite temperature is\nprovided, even with a confined solid lubricant composed of multiple (up to 6)\nlubricant layers. Characteristic backward lubricant motion produced by the\npresence of \"anti-kinks\" is also shown in this more realistic context.",
        "positive": "Massive fermions with low mobility in antiferromagnet orthorhombic\n  CuMnAs single crystals: We report the physical properties of orthorhombic o-CuMnAs single crystal,\nwhich is predicted to be a topological Dirac semimetal with magnetic ground\nstate and inversion symmetry broken. o-CuMnAs exhibits an antiferromagnetic\ntransition with TN ~ 312 K. Further characterizations of magnetic properties\nsuggest that the AFM order may be canted with the spin orientation in the bc\nplane. Small isotropic MR and linearly field-dependent Hall resistivity with\npositive slope indicate that single hole-type carries with high density and low\nmobility dominate the transport properties of o-CuMnAs. Furthermore, the result\nof low-temperature heat capacity shows that the effective mass of carriers is\nmuch larger than those in typical topological semimetals. These results imply\nthat the carriers in o-CuMnAs exhibit remarkably different features from those\nof Dirac fermions predicted in theory."
    },
    {
        "anchor": "Evaluation of homogenized thermal conductivities of imperfect\n  carbon-carbon textile composites using the Mori-Tanaka method: Three-scale homogenization procedure is proposed in this paper to provide\nestimates of the effective thermal conductivities of porous carbon-carbon\ntextile composites. On each scale - the level of fiber tow (micro-scale), the\nlevel of yarns (meso-scale) and the level of laminate (macro-scale) - a two\nstep homogenization procedure based on the Mori-Tanaka averaging scheme is\nadopted. This involves evaluation of the effective properties first in the\nabsence of pores. In the next step, an ellipsoidal pore is introduced into a\nnew, generally orthotropic, matrix to make provision for the presence of crimp\nvoids and transverse and delamination cracks resulting from the thermal\ntransformation of a polymeric precursor into the carbon matrix. Other sources\nof imperfections also attributed to the manufacturing processes, including\nnon-uniform texture of the reinforcements, are taken into consideration through\nthe histograms of inclination angles measured along the fiber tow path together\nwith a particular shape of the equivalent ellipsoidal inclusion. The analysis\nshows that a reasonable agreement of the numerical predictions with\nexperimental measurements can be achieved.",
        "positive": "Tuning the doping of epitaxial graphene on a conventional semiconductor\n  via substrate surface reconstruction: Combining scanning tunneling microscopy and angle-resolved photoemission\nspectroscopy, we demonstrate how to tune the doping of epitaxial graphene from\np to n by exploiting the structural changes that occur spontaneously on the Ge\nsurface upon thermal annealing. Furthermore, using first principle calculations\nwe build a model that successfully reproduces the experimental observations.\nSince the ability to modify graphene electronic properties is of fundamental\nimportance when it comes to applications, our results provide an important\ncontribution towards the integration of graphene with conventional\nsemiconductors."
    },
    {
        "anchor": "Functionalized Thallium Antimony Films as Excellent Candidates for\n  Large-Gap Quantum Spin Hall Insulator: Group III-V films are of great importance for their potential application in\nspintronics and quantum computing. Search for two-dimensional III-V films with\na nontrivial large-gap are quite crucial for the realization of dissipationless\ntransport edge channels using quantum spin Hall (QSH) effects. Here we use\nfirst-principles calculations to predict a class of large-gap QSH insulators in\nfunctionalized TlSb monolayers (TlSbX2; (X = H, F, Cl, Br, I)), with sizable\nbulk gaps as large as 0.22~0.40 eV. The QSH state is identified by Z2\ntopological invariant together with helical edge states induced by spin-orbit\ncoupling (SOC). Noticeably, the inverted band gap in the nontrivial states can\nbe effectively tuned by the electric field and strain. Additionally, these\nfilms on BN substrate also maintain a nontrivial QSH state, which harbors a\nDirac cone lying within the band gap. These findings may shed new light in\nfuture design and fabrication of QSH insulators based on two-dimensional\nhoneycomb lattices in spintronics.",
        "positive": "Splitting of Surface Plasmon Frequencies of Metal Particles in a Nematic\n  Liquid Crystal: We calculate the effective dielectric function for a suspension of small\nmetallic particles immersed in a nematic liquid crystal (NLC) host. For a\nrandom suspension of such particles in the dilute limit, we calculate the\neffective dielectric tensor exactly and show that the surface plasmon\n(SP)resonance of such particles splits into two resonances, polarized parallel\nand perpendicular to the NLC director. At higher concentrations, we calculate\nthis splitting using a generalized Maxwell-Garnett approximation, which can\nalso be applied to a small metal particle coated with NLC. To confirm the\naccuracy of the MGA for NLC-coated spheres, we also use the Discrete Dipole\nApproximation. The calculated splitting is comparable to that observed in\nrecent experiments on NLC-coated small metal particles"
    },
    {
        "anchor": "Micropillar compression of single crystal tungsten carbide, Part 1:\n  temperature and orientation dependence of deformation behaviour: Tungsten carbide cobalt hardmetals are commonly used as cutting tools subject\nto high operation temperature and pressures, where the mechanical performance\nof the tungsten carbide phase affects the wear and lifetime of the material. In\nthis study, the mechanical behaviour of the isolated tungsten carbide (WC)\nphase was investigated using single crystal micropillar compression.\nMicropillars in two crystal orientations, 1-5 ${\\mu}$m in diameter, were\nfabricated using focused ion beam (FIB) machining and subsequently compressed\nbetween room temperature and 600 {\\deg}C. The activated plastic deformation\nmechanisms were strongly anisotropic and weakly temperature dependent. The flow\nstresses of basal-oriented pillars were about three times higher than the\nprismatic pillars, and pillars of both orientations soften slightly with\nincreasing temperature. The basal pillars tended to deform by either unstable\ncracking or unstable yield, whereas the prismatic pillars deformed by\nslip-mediated cracking. However, the active deformation mechanisms were also\nsensitive to pillar size and shape. Slip trace analysis of the deformed pillars\nshowed that {10-10} prismatic planes were the dominant slip plane in WC. Basal\nslip was also activated as a secondary slip system at high temperatures.",
        "positive": "Large Scale Benchmark of Materials Design Methods: Lack of rigorous reproducibility and validation are major hurdles for\nscientific development across many fields. Materials science in particular\nencompasses a variety of experimental and theoretical approaches that require\ncareful benchmarking. Leaderboard efforts have been developed previously to\nmitigate these issues. However, a comprehensive comparison and benchmarking on\nan integrated platform with multiple data modalities with both perfect and\ndefect materials data is still lacking. This work introduces\nJARVIS-Leaderboard, an open-source and community-driven platform that\nfacilitates benchmarking and enhances reproducibility. The platform allows\nusers to set up benchmarks with custom tasks and enables contributions in the\nform of dataset, code, and meta-data submissions. We cover the following\nmaterials design categories: Artificial Intelligence (AI), Electronic Structure\n(ES), Force-fields (FF), Quantum Computation (QC) and Experiments (EXP). For\nAI, we cover several types of input data, including atomic structures,\natomistic images, spectra, and text. For ES, we consider multiple ES\napproaches, software packages, pseudopotentials, materials, and properties,\ncomparing results to experiment. For FF, we compare multiple approaches for\nmaterial property predictions. For QC, we benchmark Hamiltonian simulations\nusing various quantum algorithms and circuits. Finally, for experiments, we use\nthe inter-laboratory approach to establish benchmarks. There are 1281\ncontributions to 274 benchmarks using 152 methods with more than 8 million\ndata-points, and the leaderboard is continuously expanding. The\nJARVIS-Leaderboard is available at the website:\nhttps://pages.nist.gov/jarvis_leaderboard"
    },
    {
        "anchor": "Effect of Reducing Atmosphere on the Magnetism of Zn1-xCoxO\n  Nanoparticles: We report the crystal structure and magnetic properties of Zn1-xCoxO\nnanoparticles synthesized by heating metal acetates in organic solvent. The\nnanoparticles were crystallized in wurtzite ZnO structure after annealing in\nair and in a forming gas (Ar95%+H5%). The X-ray diffraction and X-ray\nphotoemission spectroscopy (XPS) data for different Co content show clear\nevidence for the Co+2 ions in tetrahedral symmetry, indicating the substitution\nof Co+2 in ZnO lattice. However samples with x=0.08 and higher cobalt content\nalso indicate the presence of Co metal clusters. Only those samples annealed in\nthe reducing atmosphere of the forming gas, and that showed the presence of\noxygen vacancies, exhibited ferromagnetism at room temperature. The air\nannealed samples remained non-magnetic down to 77K. The essential ingredient in\nachieving room temperature ferromagnetism in these Zn1-xCoxO nanoparticles was\nfound to be the presence of additional carriers generated by the presence of\nthe oxygen vacancies.",
        "positive": "Nanomechanics of Antimonene Allotropes: Monolayer antimonene has drawn the attention of research communities due to\nits promising physical properties. But mechanical properties of antimonene is\nstill largely unexplored. In this work, we investigate the mechanical\nproperties and fracture mechanisms of two stable phases of monolayer antimonene\n-- the ${\\alpha}$ antimonene (${\\alpha}$-Sb) and the ${\\beta}$ antimonene\n(${\\beta}$-Sb), through molecular dynamics (MD) simulations. Our simulations\nreveal that stronger chiral effect results in a greater anisotropic elastic\nbehavior in ${\\beta}$-antimonene than in ${\\alpha}$-antimonene. In this paper\nwe focus on crack-tip stress distribution using local volume averaged virial\nstress definition and derive the fracture toughness from the crack-line stress.\nOur calculated crack tip stress distribution ensures the applicability of\nlinear elastic fracture mechanics (LEFM) for cracked antimonene allotropes with\nconsiderable accuracy up to a pristine structure. We evaluate the effect of\ntemperature, strain rate, crack-length and point-defect concentration on the\nstrength and elastic properties. Tensile strength goes through significant\ndegradation with the increment of temperature, crack length and defect\npercentage. Elastic modulus is less susceptible to temperature variation but is\nlargely affected by the defect concentration. Strain rate induces a power law\nrelation between strength and fracture strain. Finally, we discuss the fracture\nmechanisms in the light of crack propagation and establish the links between\nthe fracture mechanism and the observed anisotropic properties."
    },
    {
        "anchor": "Quasiparticle Self-Consistent GW Theory: In past decades the scientific community has been looking for a reliable\nfirst-principles method to predict the electronic structure of solids with high\naccuracy. Here we present an approach which we call the quasiparticle\nself-consistent GW approximation (QpscGW). It is based on a kind of\nself-consistent perturbation theory, where the self-consistency is constructed\nto minimize the perturbation. We apply it to selections from different classes\nof materials, including alkali metals, semiconductors, wide band gap\ninsulators, transition metals, transition metal oxides, magnetic insulators,\nand rare earth compounds. Apart some mild exceptions, the properties are very\nwell described, particularly in weakly correlated cases. Self-consistency\ndramatically improves agreement with experiment, and is sometimes essential.\nDiscrepancies with experiment are systematic, and can be explained in terms of\napproximations made.",
        "positive": "Theory of plasmonic effects in nonlinear optics: the case of graphene: We develop a microscopic large-$N$ theory of electron-electron interaction\ncorrections to multi-legged Feynman diagrams describing second- and third-order\nnonlinear response functions. Our theory, which reduces to the well-known\nrandom phase approximation in the linear-response limit, is completely general\nand is useful to understand all second- and third-order nonlinear effects,\nincluding harmonic generation, wave mixing, and photon drag. We apply our\ntheoretical framework to the case of graphene, by carrying out microscopic\ncalculations of the second- and third-order nonlinear response functions of an\ninteracting two-dimensional (2D) gas of massless Dirac fermions. We compare our\nresults with recent measurements, where all-optical launching of graphene\nplasmons has been achieved by virtue of the finiteness of the quasi-homogeneous\nsecond-order nonlinear response of this inversion-symmetric 2D material."
    },
    {
        "anchor": "Response to \"Comment on 'Origin of the Curie--von Schweidler law and the\n  fractional capacitor from time-varying capacitance [J. Pow. Sources 532\n  (2022) 231309]' \": We welcome Allagui et al.'s discussions about our recent paper that has\nproposed revisions to the existing theory of capacitors. It gives us an\nopportunity to emphasize on the physical underpinnings of the mathematical\nexpressions that are relevant for modeling using fractional derivatives. The\nconcerns raised by Allagui et al. are found to be quite questionable when\nexamined in light of the established standard results of fractional calculus.\nConsequently, the inferences that they have drawn are not true. Finally, we\nwould like to thank Allagui et al. because this subsequent Response to their\nComment has actually led to a further consolidation of our results that are\nsupposed to be significant for materials science as well as for fractional\ncontrol systems and engineering.",
        "positive": "Solution processable and optically switchable 1D photonic structures: In this work, we report the first demonstration of a solution processable,\noptically switchable 1D photonic crystal by implementing phototunable doped\nmetal oxide nanocrystals. The resulting device structure shows bi-photonic\nresponse with the photonic bandgap covering the visible spectral range and the\nplasmon resonance of the doped metal oxide the near infrared. By means of a\nfacile photodoping process, we tuned the plasmonic response and switched\neffectively the optical properties of the photonic crystal, translating the\neffect from the near infrared to the visible. The ultrafast bandgap pumping\ninduces a signal change in the region of the photonic stopband, with recovery\ntimes of several picoseconds, providing a step toward the ultrafast optical\nswitching. Optical modeling uncovers the importance to understand largely the\nvariations of the dielectric function of the photodoped material, and\nvariations in the high frequency region of the Drude response are responsible\nfor the strong switching in the visible after photodoping. Our device\nconfiguration offers unprecedented tunablility due to flexibility in device\ndesign, cover wavelength ranges from the visible to the near infrared. Our\nfindings indicate a new protocol to modify the optical response of photonic\ndevices by optical triggers only."
    },
    {
        "anchor": "Density Functional Theory screening of gas-treatment strategies for\n  stabilization of high energy-density lithium metal anodes: To explore the potential of molecular gas treatment of freshly cut lithium\nfoils in non-electrolyte based passivation of high energy-density Li anodes,\ndensity functional theory (DFT) has been used to study the decomposition of\nmolecular gases on metallic lithium surfaces. By combining DFT geometry\noptimization and Molecular Dynamics, the effects of atmospheric (N2, O2, CO2)\nand hazardous (F2, SO2) gas decomposition on Li(bcc) (100), (110), and (111)\nsurfaces on relative surface energies, work functions, and emerging electronic\nand elastic properties are investigated. The simulations suggest that exposure\nto different molecular gases can be used to induce and control reconstructions\nof the metal Li surface and substantial changes (up to over 1 eV) in the work\nfunction of the passivated system. Contrary to the other considered gases,\nwhich form metallic adlayers, SO2 treatment emerges as the most effective in\ncreating an insulating passivation layer for dosages <= 1 mono-layer. The\nsubstantial Li->adsorbate charge transfer and adlayer relaxation produce marked\nelastic stiffening of the interface, with the smallest change shown by\nnitrogen-treated adlayers.",
        "positive": "Itinerant and local magnetic moments in ferrimagnetic Mn2CoGa thin films\n  probed by x-ray magnetic linear dichroism: experiment and ab initio theory: Epitaxial thin films of the half-metallic Xa-compound Mn2CoGa (Hg2CuTi\nprototype) were prepared by dc magnetron co-sputtering with different heat\ntreatments on MgO (001) substrates. High-quality films with a bulk\nmagnetization of 1.95(5)\\mu_B per unit cell were obtained. The L3,2 x-ray\nmagnetic circular dichroism spectra agree with calculations based on density\nfunctional theory (DFT) and reveal the antiparallel alignment of the two\ninequivalent Mn moments. X-ray magnetic linear dichroism, in good agreement\nwith theory as well, allows to distinguish between itinerant and local Mn\nmoments. Based on non-collinear spin DFT it is shown that one of the two Mn\nmoments has local character, whereas the other Mn moment and the Co moment are\nitinerant."
    },
    {
        "anchor": "Nonequilibrium Carrier Dynamics in Transition Metal Dichalcogenide\n  Semiconductors: When exploring new materials for their potential in (opto)electronic device\napplications, it is important to understand the role of various carrier\ninteraction and scattering processes. Research on transition metal\ndichalcogenide (TMD) semiconductors has recently progressed towards the\nrealisation of working devices, which involve light-emitting diodes, nanocavity\nlasers, and single-photon emitters. In these two-dimensional atomically thin\nsemiconductors, the Coulomb interaction is known to be much stronger than in\nquantum wells of conventional semiconductors like GaAs, as witnessed by the 50\ntimes larger exciton binding energy. The question arises, whether this directly\ntranslates into equivalently faster carrier-carrier Coulomb scattering of\nexcited carriers. Here we show that a combination of ab-initio band-structure\nand many-body theory predicts carrier relaxation on a 50-fs time scale, which\nis less than an order of magnitude faster than in quantum wells. These\nscattering times compete with the recently reported sub-ps exciton\nrecombination times, thus making it harder to achieve population inversion and\nlasing.",
        "positive": "A simple synthesis method for growing single crystals of a copper\n  coordination polymer [Cu(C2O4)(4-aminopyridine)2(H2O)]n, and its theoretical\n  and physical properties studies: This work reports on a novel and simple synthetic route for the growth of\nmetal-organic crystal [Cu(C2O4)(4-aminopyridine)2(H2O)]n of large size using\nthe technique of liquid-liquid diffusion or layer diffusion. Single crystal\nX-ray diffraction measurements revealed a very good quality of the grown single\ncrystals with a small value 1.101 of goodness of fit R. Rietveld refinement\ndone on powder X-ray diffractogram obtained on few single crystals crushed\ntogether revealed a very small value of R as 3.45, indicating very good crystal\nquality in a batch of crystals. Density functional theory with three different\nbasis sets generated the optimized geometry of a monomeric unit as well as its\nvibrational spectra. Comparison between experimentally obtained bond lengths,\nbond angles, IR frequencies etc. suggest (B3LYP/LanL2DZ, B3LYP/6-311++ G(d,p)\nbasis set to describe the properties the best. Magnetic susceptibility\nmeasurements confirm the metal-organic crystal\n[Cu(C2O4)(4-aminopyridine)2(H2O)]n to be a very good representation of a spin\n1/2 Heisenberg antiferromagnet."
    },
    {
        "anchor": "Elasticity and hydrodynamics of quasicrystals with 7-, 14-, 9- and\n  18-fold symmetries: This letter reports theory of elasticity and hydrodynamics of quasicrystals\nwith 7-, 14-, 9- and 18-fold symmetries in solid phase, in which the\n6-dimensional embedding space concept is used. Based on the concept and the\nLandau-Anderson symmetry breaking principle and the Lubensky hydrodynamics, the\ngoverning equations for the above quasicrystal systems have been set up, the\nsolving procedure for the initial-boundary value problems of the equations is\ndiscussed as well. Though the discussion is concerned only for the\nquasicrystals, in particular for one of 18-fold symmetry, in solid phase, it\nmay be a basis for those in soft matter phase observed recently.",
        "positive": "Large nonsaturating magnetoresistance and signature of non-degenerate\n  Dirac nodes in ZrSiS: While the discovery of Dirac and Weyl type excitations in electronic systems\nis a major breakthrough in recent condensed matter physics, finding appropriate\nmaterials for fundamental physics and technological applications, is an\nexperimental challenge. In all the reported materials, linear dispersion\nsurvives only up to a few hundred meV from the Dirac or Weyl nodes. On the\nother hand, real materials are subject to uncontrolled doping during\npreparation and thermal effect near room temperature can hinder the rich\nphysics. In ZrSiS, ARPES measurements have shown an unusually robust linear\ndispersion (up to $\\sim$2 eV) with multiple non-degenerate Dirac nodes. In this\ncontext, we present the magnetotransport study on ZrSiS crystal, which\nrepresents a large family of materials (\\textit{WHM} with \\textit{W} = Zr, Hf;\n\\textit{H} = Si, Ge, Sn; \\textit{M} = O, S, Se, Te) with identical band\ntopology. Along with extremely large and non-saturating magnetoresistance (MR),\n$\\sim$ 1.4 $\\times$ 10$^{5}$ \\% at 2 K and 9 T, it shows strong anisotropy\ndepending on the direction of the magnetic field. Quantum oscillation and Hall\neffect measurements have revealed large hole and small electron Fermi pockets.\nNon-trivial $\\pi$ Berry phase confirms the Dirac fermionic nature for both\ntypes of charge carriers. The long-sought relativistic phenomenon of massless\nDirac fermions, known as Adler-Bell-Jackiw chiral anomaly, has also been\nobserved."
    },
    {
        "anchor": "Accelerating materials discovery for polymer solar cells: Data-driven\n  insights enabled by natural language processing: We present a natural language processing pipeline that was used to extract\npolymer solar cell property data from the literature and simulate various\nactive learning strategies. While data-driven methods have been well\nestablished to discover novel materials faster than Edisonian trial-and-error\napproaches, their benefits have not been quantified. Our approach demonstrates\na potential reduction in discovery time by approximately 75 %, equivalent to a\n15 year acceleration in material innovation. Our pipeline enables us to extract\ndata from more than 3300 papers which is ~5 times larger than similar data sets\nreported by others. We also trained machine learning models to predict the\npower conversion efficiency and used our model to identify promising\ndonor-acceptor combinations that are as yet unreported. We thus demonstrate a\nworkflow that goes from published literature to extracted material property\ndata which in turn is used to obtain data-driven insights. Our insights include\nactive learning strategies that can simultaneously optimize the material system\nand train strong predictive models of material properties. This work provides a\nvaluable framework for research in material science.",
        "positive": "Electrical magnetochiral anisotropy in trigonal tellurium from first\n  principles: Structural chirality induces characteristic responses that change sign with\nthe handedness of the crystal structure. One example is electrical\nmagnetochiral anisotropy (eMChA), a change in resistivity that depends linearly\non the applied current and magnetic field. A strong eMChA was recently reported\nfor $p$-doped tellurium. With this motivation, we carry out an \\textit{ab\ninitio} study of its bulk eMChA response as a function of temperature and\ndoping concentration. We use the semiclassical Boltzmann transport formalism\nwithin the constant relaxation-time approximation to express the current\ndensity at order $E^2B$ in terms of the energy dispersion, intrinsic magnetic\nmoment, and Berry curvature of conduction electrons. We find that the orbital\nZeeman coupling dominates the response, with smaller contributions coming from\nthe spin-Zeeman coupling and from the Berry curvature. The agreement with the\navailable experimental data is satisfactory."
    },
    {
        "anchor": "Non-Linear Modes in Lithium Niobate Ferroelectrics with niobium antisite\n  defects: Ferroelectric belongs to an important class of materials showing very\ninteresting nonlinear optical properties that have a variety of application in\nphotonic devices In a discrete Hamiltonian, if we consider the space and time\ndependence of polarization vectors with an interaction term between two\npolarization domains, it gives rise to a nonlinear Klein-Gordon (K-G) equation\nthat has been shown in some systems [1]. This equation as a governing equation\nenables multiple time-scale analysis (MTSA) to be performed on a real\nferroelectric material that reveals new type of information on both linear\n(known as soft modes) and the nonlinear parts of frequencies and amplitudes of\noscillations. MTSA was described in a K-G system based on staggered\npolarization where more emphasis was given to reveal the presence of intrinsic\nlocalized modes (ILM). Here, detailed results for the first three linear modes\nand their frequencies as a 2 function of a wide range of niobium antisite\ndefects or, impurities in lithium niobate ferroelectric are presented. It is\nfound that when an external excitation (i.e. the input) is only harmonic in\nnature, it could not be ascertained whether the even modes of the solitonic\nwaves (i.e. the output) will have phase-locking with this type of harmonic\nexternal force.",
        "positive": "Isotope effect, Thermodynamic and Elastic properties of ZrCo and ZrCoH3:\n  An ab-initio study: The intermetallic compound ZrCo and its hydrides are important materials for\ntheir use in hydrogen isotope storage. The dynamical, thermodynamic and elastic\nproperties of ZrCo and its hydrides ZrCoX3 (X= H, D and T) are reported. While\nthe electronic structure calculations are performed using plane wave\npseudopotential approach, the effect of isotopes on the vibrational and\nthermodynamic properties has been demonstrated through frozen phonon approach.\nThe results reveal significant difference between the ZrCoH3 and its isotopic\nanalogs in terms of phonon frequencies and zero point energies. For example,\nthe energy gap between optical and acoustic modes reduces in the order of\nZrCoT3 > ZrCoD3 > ZrCoH3. The calculated formation energies of ZrCoX3,\nincluding the ZPE, are -146.7, -158.3 and -164.1 kJ/(mole of ZrCoX3) for X = H,\nD and T, respectively. In addition, the changes in elastic properties of ZrCo\nupon hydrogenation have also been investigated. The results show that both ZrCo\nand ZrCoH3 are mechanically stable at ambient pressure. The Debye temperatures\nof both ZrCo and ZrCoH3 are determined using the calculated elastic moduli."
    },
    {
        "anchor": "Representing molecule-surface interactions with symmetry-adapted neural\n  networks: The accurate description of molecule-surface interactions requires a detailed\nknowledge of the underlying potential-energy surface (PES). Recently, neural\nnetworks (NNs) have been shown to be an efficient technique to accurately\ninterpolate the PES information provided for a set of molecular configurations,\ne.g. by first-principles calculations. Here, we further develop this approach\nby building the NN on a new type of symmetry functions, which allows to take\nthe symmetry of the surface exactly into account. The accuracy and efficiency\nof such symmetry-adapted NNs is illustrated by the application to a\nsix-dimensional PES describing the interaction of oxygen molecules with the\nAl(111) surface.",
        "positive": "Narrowing of d bands of FeCo layers intercalated under graphene: We report on the electronic properties of an artificial system obtained by\nthe intercalation of equiatomic FeCo layers under graphene grown on Ir(111).\nUpon intercalation, the FeCo film grows epitaxially on Ir(111), resulting in a\nlattice-mismatched system. By performing Density Functional Theory\ncalculations, we show that the intercalated FeCo layer leads to a pronounced\ncorrugation of the graphene film. At the same time, the FeCo intercalated\nlayers induce a clear transition from a nearly undisturbed to a strongly\nhybridized graphene {\\pi}-band, as measured by angle-resolved photoemission\nspectroscopy. A comparison of experimental results with the computed band\nstructure and the projected density of states unveils a spin-selective\nhybridization between the {\\pi} band of graphene and FeCo-3d states. Our\nresults demonstrate that the reduced dimensionality, as well as the\nhybridization within the FeCo layers, induce a narrowing and a clear splitting\nof Fe 3d-up and Fe 3d-down spin bands of the confined FeCo layers with respect\nto bulk Fe and Co."
    },
    {
        "anchor": "Magnetically induced electronic ferroelectricity in half-doped\n  manganites: Using a joint approach of density functional theory and model calculations,\nwe demonstrate that a prototypical charge ordered half-doped manganite,\nLa$_{1/2}$Ca$_{1/2}$MnO$_3$ is multiferroic. The combination of a peculiar\ncharge-orbital ordering and a tendency to form spin dimers breaks inversion\nsymmetry, leads to a ferroelectric ground-state with a polarization up to\nseveral $\\mu C/cm^2$. The presence of improper ferroelectricity does not depend\non hotly debated structural details of this material: in the Zener-polaron\nstructure we find a similar dramatic ferroelectric response with a large\npolarization of purely magnetic origin.",
        "positive": "Structural and angular dependence of coercivity and magnetic remanence\n  of electrochemical ferromagnetic nanowires: A novel method for controlling nanowire magnetic properties and growth from\nfilling time profile is presented.\n  The wires are grown with an electrodeposition method (\"Template synthesis\")\nwith a wide selection of pore diameters. We show that stray-fields presence in\nferromagnetic nanowires are entirely dependent on the nanowire diameter.\nBesides a crossover effect in the reversal mechanism is observed with change in\ndiameter. In this work, theory and experiment agree and confirm that according\nto the variety of hysteresis loop measured, about four ranges of values of pore\ndiameter control the orientation of nanowire magnetization easy axis with\nrespect to the geometrical axis."
    },
    {
        "anchor": "Accidental degeneracy and topological phase transitions in\n  two-dimensional core-shell dielectric photonic crystals: A simple core-shell two-dimensional photonic crystal is studied where the\ntriangle lattice symmetry and $C_{6v}$ rotation symmetry leads to rich physics\nin the study of accidental degeneracy's in photonic bands. We systematically\nevaluate different types of accidental nodal points, depending on the\ndispersions around them and their topological properties, when the geometry and\npermittivity are continuously changed. These accidental nodal points can be the\ncritical states lying between a topological phase and a normal phase and are\nthus important for the study of topological photonic states. In time-reversal\nsystems, this leads to the photonic quantum spin Hall insulator where the spin\nis defined upon the orbital angular momentum for transverse-magnetic\npolarization. We study the topological phase transition as well as the\nproperties of the edge and bulk states and their application potentials in\noptics.",
        "positive": "Direct observation of double valence-band extrema and anisotropic\n  effective masses of the thermoelectric material SnSe: Synchrotron-based angle-resolved photoemission spectroscopy is used to\ndetermine the electronic structure of layered SnSe, which was recently turned\nout to be a potential thermoelectric material. We observe that the top of the\nvalence band consists of two nearly independent hole bands, whose tops differ\nby ~20 meV in energy, indicating the necessity of a multivalley model to\ndescribe the thermoelectric properties. The estimated effective masses are\nanisotropic, with in-plane values of 0.16-0.39 m$_0$ and an out-of-plane value\nof 0.71 m$_0$, where m$_0$ is the rest electron mass. Information of the\nelectronic structure is essential to further enhance the thermoelectric\nperformance of hole-doped SnSe."
    },
    {
        "anchor": "Multiphase density functional theory parameterization of the Gupta\n  potential for silver and gold: The ground state energies of Ag and Au in the face-centered cubic (FCC),\nbody-centered cubic (BCC), simple cubic (SC) and the hypothetical diamond-like\nphase, and dimer were calculated as a function of bond length using density\nfunctional theory (DFT). These energies were then used to parameterize the\nmany-body Gupta potential for Ag and Au. This parameterization over several\nphases of Ag and Au was performed to guarantee transferability of the\npotentials and to make them appropriate for studies of related nanostructures.\nDepending on the structure, the energetics of the surface atoms play a crucial\nrole in determining the details of the nanostructure. The accuracy of the\nparameters was tested by performing a 2 ns MD simulation of a cluster of 55 Ag\natoms -- a well studied cluster of Ag, the most stable structure being the\nicosahedral one. Within this time scale, the initial FCC lattice was found to\ntransform to the icosahedral structure at room temperature. The new set of\nparameters for Ag was then used in a temperature dependent atom-by-atom\ndeposition of Ag nanoclusters of up to 1000 atoms. We find a deposition\ntemperature of 500 $\\pm$50 K where low energy clusters are generated,\nsuggesting an optimal annealing temperature of 500 K for Ag cluster synthesis.",
        "positive": "Multi-exposure diffraction pattern fusion applied to enable wider-angle\n  transmission Kikuchi diffraction with direct electron detectors: Diffraction pattern analysis can be used to reveal the crystalline structure\nof materials, and this information is used to nano- and micro-structure of\nadvanced engineering materials that enable modern life. For nano-structured\nmaterials typically diffraction pattern analysis is performed in the\ntransmission electron microscope (TEM) and TEM diffraction patterns typically\nhave a limited angular range (less than a few degrees) due to the long camera\nlength, and this requires analysis of multiple patterns to probe a unit cell.\nAs a different approach, wide angle Kikuchi patterns can be captured using an\non-axis detector in the scanning electron microscope (SEM) with a shorter\ncamera length. These 'transmission Kikuchi diffraction' (TKD) patterns present\na direct projection of the unit cell and can be routinely analyzed using\nEBSD-based methods and dynamical diffraction theory. In the present work, we\nenhance this analysis significantly and present a multi-exposure diffraction\npattern fusion method that increases the dynamic range of the detected patterns\ncaptured with a Timepix3-based direct electron detector (DED). This method uses\nan easy-to-apply exposure fusion routine to collect data and extend the dynamic\nrange, as well as normalize the intensity distribution within these very wide\n(>95{\\deg}) angle patterns. The potential of this method is demonstrated with\nfull diffraction sphere reprojection and highlight potential of the approach to\nrapidly probe the structure of nano-structured materials in the scanning\nelectron microscope."
    },
    {
        "anchor": "Exploring the Correlation between Solvent Diffusion and Creep Resistance\n  of Mg-Ga HCP Alloys from High Throughput Liquid-Solid Diffusion Couple: The liquid-solid diffusion couple technique, supported by phenomenological\nanalysis and nano-indentation tests, is proposed on account of the relatively\nlow melting points of Mg to explore the diffusion mobility and creep\ndeformation. The potential of this strategy is demonstrated in Mg-Ga hcp alloys\nwhere Ga solute (i.e. impurity) and Mg solvent diffusions in hcp Mg-Ga alloys\nwere both unveiled. It was followed by mapping the compressive creep behavior\nvia nanoindentation along the composition arrays within the same Mg-Ga couple\nsample. The compressive creep resistance of Mg-Ga hcp alloys increased with the\nGa content, and this enhancement was similar to the one found in Mg-Zn alloys\nand superior to the one reported in Mg-Al alloys though Al is a slower impurity\ndiffuser in hcp-Mg than Zn and Ga. Thereby, the solvent diffusion and its\nvariation with the composition, rather than the solute diffusion, was suggested\nto govern the creep properties at high temperatures and low stresses.",
        "positive": "Physics in the Machine: Integrating Physical Knowledge in Autonomous\n  Phase-Mapping: Application of artificial intelligence (AI), and more specifically machine\nlearning, to the physical sciences has expanded significantly over the past\ndecades. In particular, science-informed AI, also known as scientific AI or\ninductive bias AI, has grown from a focus on data analysis to now controlling\nexperiment design, simulation, execution and analysis in closed-loop autonomous\nsystems. The CAMEO (closed-loop autonomous materials exploration and\noptimization) algorithm employs scientific AI to address two tasks: learning a\nmaterial system's composition-structure relationship and identifying materials\ncompositions with optimal functional properties. By integrating these,\naccelerated materials screening across compositional phase diagrams was\ndemonstrated, resulting in the discovery of a best-in-class phase change memory\nmaterial. Key to this success is the ability to guide subsequent measurements\nto maximize knowledge of the composition-structure relationship, or phase map.\nIn this work we investigate the benefits of incorporating varying levels of\nprior physical knowledge into CAMEO's autonomous phase-mapping. This includes\nthe use of ab-initio phase boundary data from the AFLOW repositories, which has\nbeen shown to optimize CAMEO's search when used as a prior."
    },
    {
        "anchor": "Dirty Spin Ice: The Effect of Dilution on Spin Freezing in Dy2Ti2O7: We have studied spin freezing in the diluted spin ice compound Dy2-xYxTi2O7\nwhere the non-magnetic Y ions replace the magnetic Dy ions on the frustrated\npyrochlore lattice. Magnetic a.c. and d.c. susceptibility data are presented\nwith an analysis of relaxation times for dilutions of x = 0, 0.1, 0.2, and 0.4.\nSite dilution apparently decreases the relative number of spins participating\nin the ice-like freezing near 16 K while leaving the freezing temperature\nunchanged. Correspondingly the distribution of relaxation times associated with\nthe freezing is broadened only slightly with increasing dilution, suggesting\nthat the freezing process observed near T = 16 K involves local correlations\namong the spins.",
        "positive": "Nanostructured Pt-Doped 2D MoSe$_2$: An Efficient Bifunctional\n  Electrocatalyst for both Hydrogen Evolution and Oxygen Reduction Reactions: TMDs are a new family of 2D materials with features that make them appealing\nfor potential applications in nanomaterials science and engineering. Although,\nthe edges of the 2D TMDs show excellent electrocatalytic performance, their\nbasal plane is inert which hinders the industrial applications for\nelectrocatalysis. Here, we have computationally designed the 2D monolayer\nMoSe$_2$ and studied its electronic properties with electrocatalytic\nactivities. Pt-atom has been doped in the pristine 2D MoSe$_2$ to activate the\ninert basal plane resulting zero bandgap. This study reveals that the\nPt-MoSe$_2$ is an excellent bifunctional electrocatalyst for both the hydrogen\nevolution reaction (HER) and oxygen reduction reaction (ORR) with the aid of\nthe DFT. Periodic hybrid DFT method has been applied to compute the electronic\nproperties of both the pristine MoSe$_2$ and Pt-MoSe$_2$. To determine both the\nHER and ORR mechanisms on the surface of the Pt-MoSe2 material, a non-periodic\nDFT calculation has been performed by considering a molecular\nPt1-Mo$_9$Se${21}$ cluster model. The present study shows that the 2D\nPt-MoSe$_2$ follows Volmer-Heyrovsky mechanism for HER with the energy barriers\nabout 9.29 kcal/mol and 10.55 kcal.mol-1 during the H-migration and Heyrovsky\nreactions. The ORR is achieved by four-electron transfer mechanism with the\nformation of two transition energy barriers about 14.94 kcal/mol and 11.10\nkcal/mol, respectively. The lower energy barriers and high turnover frequency\nduring the reactions expose that the Pt-MoSe$_2$ can be adopted as an efficient\nbifunctional electrocatalyst for both the HER and ORR. The present studies\ndemonstrate that the exceptional HER and ORR activity and stability performance\nshown by the MoSe$_2$ electrocatalyst can be enhanced by Pt-doping, opening a\npromising concept for the sensible design of high-performance catalyst for H2\nproduction and O2 reduction."
    },
    {
        "anchor": "Triggering the Continuous Growth of Graphene toward Millimeter Size\n  Grain: In this report, we demonstrated a simple but efficient strategy to synthesize\nmillimeter-sized graphene single crystal grains by regulating the supply of\nreactants in chemical vapor deposition process. Polystyrene was used as a\ncarbon source. Pulse heating on the carbon source was utilized to minimize the\nnucleation density of graphene on copper foil, while the gradual increase in\nthe temperature of carbon source and the flow rate of hydrogen is adapted to\ndrive the continuous growth of graphene grain. As a result, the nucleation\ndensity of graphene grain can be controlled as lower as ~100 nuclei/cm2, and\nthe dimension of single crystal grain could grow up to ~1.2 mm. Raman\nspectroscopy, transmission electron microscopy and electrical transport\nmeasurement show that the graphene grains obtained are in high quality. The\nstrategy presented here provides very good controllability and enables the\npossibility for large graphene single crystals, which is of vital importance\nfor practical applications.",
        "positive": "Application of Zeeman spatial beam-splitting in polarized neutron\n  reflectometry: Neutron Zeeman spatial beam-splitting is considered at reflection from\nmagnetically noncollinear films. Two applications of Zeeman beam-splitting\nphenomenon in polarized neutron reflectometry are discussed. One is the\nconstruction of polarizing devices with high polarizing efficiency. Another one\nis the investigations of magnetically noncollinear films with low spin-flip\nprobability. Experimental results are presented for illustration."
    },
    {
        "anchor": "First-principles calculations on temperature- dependent elastic\n  constants of rare-earth intermetallic compounds:YAg and YCu: we present the temperature-dependent elastic constants of two ductile\nrare-earth intermetallic compounds YAg and YCu with CsCl-type B2 structure by\nusing a first-principles approach. The elastic moduli as a function of\ntemperature are predicted from the combination of static volumedependent\nelastic constants obtained by the first-principles total-energy method with\ndensity functional theory and the thermal expansion obtained by the\nfirst-principles phonon calculations with density-functional perturbation\ntheory. The comparison between our calculated results and the available\nexperimental data for Ag and Cu provides good agreements. In the calculated\ntemperature $0-1000K$, the elastic constants of YAg and YCu follow a normal\nbehavior with temperature that those decrease with increasing temperature, and\nsatisfy the stability conditions for B2 structures. The Cauchy pressure for YAg\nand YCu as a function of temperature is also discussed, and our results mean\nthat YAg and YCu become more ductile while increasing temperature.",
        "positive": "Differential electron yield imaging with STXM: Total electron yield (TEY) imaging is an established scanning transmission\nX-ray microscopy (STXM) technique that gives varying contrast based on a\nsample's geometry, elemental composition, and electrical conductivity. However,\nthe TEY-STXM signal is determined solely by the electrons that the beam ejects\nfrom the sample. A related technique, X-ray beam-induced current (XBIC)\nimaging, is sensitive to electrons and holes independently, but requires\nelectric fields in the sample. Here we report that multi-electrode devices can\nbe wired to produce differential electron yield (DEY) contrast, which is also\nindependently sensitive to electrons and holes, but does not require an\nelectric field. Depending on whether the region illuminated by the focused STXM\nbeam is better connected to one electrode or another, the DEY-STXM contrast\nchanges sign. DEY-STXM images thus provide a vivid map of a device's\nconnectivity landscape, which can be key to understanding device function and\nfailure. To demonstrate an application in the area of failure analysis, we\nimage a 100~nm, lithographically-defined aluminum nanowire that has failed\nafter being stressed with a large current density."
    },
    {
        "anchor": "Tuning the spontaneous exchange bias effect in La1.5Sr0.5CoMnO6 with\n  sintering temperature: Here, we present a study of the influence of microstructure on the magnetic\nproperties of polycrystalline samples of the La1.5Sr0.5CoMnO6 double\nperovskite, with primary attention to the spontaneous exchange bias effect, a\nfascinating recently discovered phenomena for which some materials exhibit\nunidirectional magnetic anisotropy after being cooled in zero magnetic field.\nBy sintering La1.5Sr0.5CoMnO6 at different temperatures, we obtained samples\nwith distinct average grain sizes, ranging from 0.76(21) to 4.95(1.73) mu_m. A\ndetailed investigation of the material's structural, morphologic, electronic,\nand magnetic properties using X-ray powder diffraction, powder neutron\ndiffraction, X-ray absorption near edge structure spectroscopy, scanning\nelectron microscopy, and AC and DC magnetometry has revealed a systematic\nenhancement of the exchange bias effect with increasing the grain size and the\nintergrain coalescence. Our results regarding the strengthening of the exchange\ncoupling at the grain interfaces and its influence on the dynamics of the spin\nglass-like moments present in the samples are discussed.",
        "positive": "Quantum Monte Carlo method for metal catalysis: case study of hydrogen\n  production on Pt(111): Over 90 % of all chemical manufacture uses a solid catalyst. Related work\nthus responds to major societal demand. This study is of water-gas shift on\nplatinum for hydrogen production. The close-packed Pt(111) surface catalyses\nthis process.\n  Many chemical reactions involve bond-dissociation. This is also true for\nreactions at solid surfaces, in which the dissociation step is often limiting\nbut facilitated in comparison to gas phase reaction channels. Since\nbond-breaking is poorly described by Hartree-Fock and DFT methods, this work\nadopts Quantum Monte Carlo (QMC) methodology. QMC is a stochastic approach to\nsolving the Schr\\\"odinger equation recently came of age for heterogeneous\nsystems involving solids.\n  The present work considers co-adsorption of water and carbon monoxide on\nPt(111). The water is partially dissociated while its oxygen atom binds to CO\nlosing a hydrogen atom. This concerted step is rate-limiting. The resulting\nadsorbed formate species then decomposes to readily eliminated carbon dioxide\nand the clean-fuel product is H$_2$.\n  The Transition-State geometry can be optimized using molecular Quantum Monte\nCarlo force constants, on the basis of our earlier work using the CASINO\nsoftware.\n  Our embedded active site approach is used. This allows a high-level\nconfiguration interaction (CI) wave-function to be used, expanded in\nplane-waves and embedded in the metal lattice exposing its close-packed face.\nThe resulting periodic function is used to guide the Quantum Monte Carlo\ncalculation.\n  Results are given here on mechanism and QMC activation barrier for water\naddition to CO pre-adsorbed on Pt(111) of 17 +/- 0.2 c.f. apparent measured\nvalue of 17.05 kcal/mol. They are encouraging for investigating similar or\ncomplex catalytic systems."
    },
    {
        "anchor": "Intrinsic and tunable quantum anomalous Hall effect and magnetic\n  topological phases in XYBi2Te5: By first-principles calculations, we study the magnetic and topological\nproperties of XYBi2Te5-family (X, Y = Mn, Ni, V, Eu) compounds. The strongly\ncoupled double magnetic atom-layers can significantly enhance the magnetic\nordering temperature while keeping the topologically nontrivial properties.\nParticularly, NiVBi2Te5 is found to be a magnetic Weyl semimetal in bulk and a\nChern insulator in thin film with both the Curie temperature (~150 K) and full\ngap well above 77 K. Ni2Bi2Te5, MnNiBi2Te5, NiVBi2Te5 and NiEuBi2Te5 exhibits\nintrinsic dynamic axion state. Among them, MnNiBi2Te5 has a Neel temperature\nover 200 K and Ni2Bi2Te5 even demonstrates antiferromagnetic order above room\ntemperature. These results indicate an approach to realize high temperature\nquantum anomalous Hall effect and other topological quantum effects for\npractical applications.",
        "positive": "Spin polarized transport current in n-type co-doped ZnO thin films\n  measured by Andreev spectroscopy: We use point contact Andreev reflection measurements to determine the spin\npolarization of the transport current in pulse laser deposited thin films of\nZnO with 1% Al and with and without 2%Mn. Only films with Mn are ferromagnetic\nand show spin polarization of the transport current of up to 55 $\\pm$ 0.5% at\n4.2 K, in sharp contrast to measurements of the nonmagnetic films without Mn\nwhere the polarization is consistent with zero. Our results imply strongly that\nferromagnetism in these Al doped ZnO films requires the presence of Mn."
    },
    {
        "anchor": "Strain Engineering of Magnetic Anisotropy in Epitaxial Films of Cobalt\n  Ferrite: Perpendicular magnetic anisotropy (PMA) energy up to\n$K_{\\mathrm{u}}=6.1\\pm0.8$ MJ m$^{-3}$ is demonstrated in this study by\ninducing large lattice-distortion exceeding 3% at room temperature in\nepitaxially distorted cobalt ferrite Co$ _{x} $Fe$ _{3-x} $O$ _{4} $ (x = 0.72)\n(001) thin films. Although the thin film materials include no rare-earth\nelements or noble metals, the observed $ K_{u} $ is larger than that of the\nneodymium-iron-boron compounds for high-performance permanent magnets. The\nlarge PMA is attributed to the significantly enhanced magneto-elastic effects,\nwhich are pronounced in distorted films with epitaxial lattice structures upon\nintroducing a distortion control layer of composition Mg$ _{2-x} $Sn$_{1+x}$O$\n_{4} $. Surprisingly, the induced $ K_{u} $ can be quantitatively explained in\nterms of the agreement between the local crystal field of Co$ ^{2+} $ and the\nphenomenological magneto-elastic model, indicating that the linear response of\ninduced $K_u$ is sufficiently valid even under lattice distortions as large as\n3.2%. Controlling tetragonal lattice deformation using a non-magnetic spinel\nlayer for ferrites could be a promising protocol for developing materials with\nlarge magnetic anisotropies.",
        "positive": "Density-operator theory of orbital magnetic susceptibility in periodic\n  insulators: The theoretical treatment of homogeneous static magnetic fields in periodic\nsystems is challenging, as the corresponding vector potential breaks the\ntranslational invariance of the Hamiltonian. Based on density operators and\nperturbation theory, we propose, for insulators, a periodic framework for the\ntreatment of magnetic fields up to arbitrary order of perturbation, similar to\nwidely used schemes for electric fields. The second-order term delivers a new,\nremarkably simple, formulation of the macroscopic orbital magnetic\nsusceptibility for periodic insulators. We validate the latter expression using\na tight-binding model, analytically from the present theory and numerically\nfrom the large-size limit of a finite cluster, with excellent numerical\nagreement."
    },
    {
        "anchor": "Parallel, Series, and Intermediate Interconnections of Optical\n  Nanocircuit Elements Part 1: Analytical Solution: Following our recent development of the paradigm for extending the classic\nconcepts of circuit elements to the infrared and optical frequencies [N.\nEngheta, A. Salandrino, A. Alu, Phys. Rev. Lett. 95, 095504 (2005)], in this\npaper we investigate the possibility of connecting nanoparticles in series and\nin parallel configurations, acting as nanocircuit elements, In particular, we\nanalyze a pair of conjoined half-cylinders, whose relatively simple geometry\nmay be studied and analyzed analytically. In this first part of the work, we\nderive a closed-form quasi-static analytical solution of the boundary-value\nproblem associated with this geometry, which will be applied in Part II for a\nnanocircuit and physical interpretation of these results.",
        "positive": "Sensitivity of Crystal Stress Distributions to the Definition of Virtual\n  Two-Phase Microstructures: A systematic study of the sensitivities of simulation input on the computed\nstress distributions in two-phase microstructures is presented. The study\nsupports a related investigation of the initiation and propagation of yielding\nin duplex stainless steel. Considered in the study are the identification of\nconstitutive model parameters for the single-crystal elastic and plastic\nbehaviors and the importance of including dominant phase and grain morphologies\nin the instantiation of virtual samples. Behaviors computed using a finite\nelement formulation are evaluated against experimental data for the macroscopic\nstress-strain behavior and against lattice strain data measured by neutron\ndiffraction under in situ loading."
    },
    {
        "anchor": "Thickness-dependent magnetic properties in Pt[CoNi]n multilayers with\n  perpendicular magnetic anisotropy: We systematically investigated the Ni and Co thickness-dependent\nperpendicular magnetic anisotropy (PMA) coefficient, magnetic domain\nstructures, and magnetization dynamics of Pt(5 nm)/[Co(t_Co nm)/Ni(t_Ni\nnm)]5/Pt(1 nm) multilayers by combining the four standard magnetic\ncharacterization techniques. The magnetic-related hysteresis loops obtained\nfrom the field-dependent magnetization M and anomalous Hall resistivity (AHR)\n\\r{ho}_xy found that the two serial multilayers with t_Co = 0.2 and 0.3 nm have\nthe optimum PMA coefficient K_U well as the highest coercivity H_C at the Ni\nthickness t_Ni = 0.6 nm. Additionally, the magnetic domain structures obtained\nby Magneto-optic Kerr effect (MOKE) microscopy also significantly depend on the\nthickness and K_U of the films. Furthermore, the thickness-dependent linewidth\nof ferromagnetic resonance is inversely proportional to K_U and H_C, indicating\nthat inhomogeneous magnetic properties dominate the linewidth. However, the\nintrinsic Gilbert damping constant determined by a linear fitting of\nfrequency-dependent linewidth does not depend on Ni thickness and K_U. Our\nresults could help promote the PMA [Co/Ni] multilayer applications in various\nspintronic and spin-orbitronic devices.",
        "positive": "Quantifying Inactive Lithium in Lithium Metal Batteries: Inactive lithium (Li) formation is the immediate cause of capacity loss and\ncatastrophic failure of Li metal batteries. However, the chemical component and\nthe atomic level structure of inactive Li have rarely been studied due to the\nlack of effective diagnosis tools to accurately differentiate and quantify Li+\nin solid electrolyte interphase (SEI) components and the electrically isolated\nunreacted metallic Li0, which together comprise the inactive Li. Here, by\nintroducing a new analytical method, Titration Gas Chromatography (TGC), we can\naccurately quantify the contribution from metallic Li0 to the total amount of\ninactive Li. We uncover that the Li0, rather than the electrochemically formed\nSEI, dominates the inactive Li and capacity loss. Using cryogenic electron\nmicroscopies to further study the microstructure and nanostructure of inactive\nLi, we find that the Li0 is surrounded by insulating SEI, losing the electronic\nconductive pathway to the bulk electrode. Coupling the measurements of the Li0\nglobal content to observations of its local atomic structure, we reveal the\nformation mechanism of inactive Li in different types of electrolytes, and\nidentify the true underlying cause of low Coulombic efficiency in Li metal\ndeposition and stripping. We ultimately propose strategies to enable the highly\nefficient Li deposition and stripping to enable Li metal anode for next\ngeneration high energy batteries."
    },
    {
        "anchor": "Electrochemical supercapacitor performance of SnO2 quantum dots: Metal oxide nanostructures are widely used in energy applications like super\ncapacitors and Li-on battery. Smaller size nanocrystals show better stability,\nlow ion diffusion time, higher-ion flux and low pulverization than bigger size\nnanocrystals during electrochemical operation. Studying the distinct properties\nof smaller size nanocrystals such as quantum dots (QDs) can improve the\nunderstanding on reasons behind the better performance and it will also help in\nusing QDs or smaller size nanoparticles (NPs) more efficiently in different\napplications. Aqua stable pure SnO2 QDs with compositional stability and high\nsurface to volume ratio are studied as an electrochemical super capacitor\nmaterial and compared with bigger size NPs of size 25 nm. Electron energy-loss\nspectroscopic study of the QDs revealed dominant role of surface over the bulk.\nTemperature dependent study of low frequency Raman mode and defect Raman mode\nof QDs indicated no apparent volume change in the SnO2 QDs within the\ntemperature range of 80-300 K. The specific capacitance of these high surface\narea and stable SnO2 QDs has showed only 9% loss while increasing the scan rate\nfrom 20 mV/S to 500 mV/S. Capacitance loss for the QDs is less than 2% after\n1000 cycles of charging discharging, whereas for the 25 nm SnO2 NPs, the\ncapacitance loss is 8% after 1000 cycles. Availability of excess open volume in\nQDs leading to no change in volume during the electro-chemical operation and\ngood aqua stability is attributed to the better performance of QDs over bigger\nsized NPs.",
        "positive": "Atomistic-continuum modeling of short laser pulse melting of Si targets: We present an atomistic-continuum model to simulate ultrashort laser-induced\nmelting processes in semiconductor solids on the example of silicon. The\nkinetics of transient non-equilibrium phase transition mechanisms is addressed\nwith a Molecular Dynamics method at atomic level, whereas the laser light\nabsorption, strong generated electron-phonon non-equilibrium, fast diffusion\nand heat conduction due to photo-excited free carriers are accounted for in the\ncontinuum. We give a detailed description of the model, which is then applied\nto study the mechanism of short laser pulse melting of free standing Si films.\nThe effect of laser-induced pressure and temperature of the lattice on the\nmelting kinetics is investigated. Two competing melting mechanisms,\nheterogeneous and homogeneous, were identified. Apart of classical\nheterogeneous melting mechanism, the nucleation of the liquid phase\nhomogeneously inside the material significantly contributes to the melting\nprocess. The simulations showed, that due to the open diamond structure of the\ncrystal, the laser-generated internal compressive stresses reduce the crystal\nstability against the homogeneous melting. Consequently, the latter can take a\nmassive character within several picoseconds upon the laser heating. Due to\nnegative volume of melting of modeled Si material, -7.5%, the material\ncontracts upon the phase transition, relaxes the compressive stresses and the\nsubsequent melting proceeds heterogeneously until the excess of thermal energy\nis consumed. The threshold fluence value, at which homogeneous nucleation of\nliquid starts contributing to the classical heterogeneous propagation of the\nsolid-liquid interface, is found from the series of simulations at different\nlaser input fluences. On the example of Si, the laser melting kinetics of\nsemiconductors was found to be noticeably different from that of metals with\nfcc crystal structure."
    },
    {
        "anchor": "V$_2$C-based lithium batteries: The influence of magnetic phase and\n  Hubbard interaction: MXenes are a family of two-dimensional materials that could be attractive for\nuse as electrodes in lithium batteries due to their high specific capacity. For\nthis purpose, it is necessary to evaluate magnitudes such as the lithium\nadsorption energy and the magnitude of the open-circuit voltage for different\nlithium concentrations. In this paper, we show through first principles\ncalculations that in a V$_2$C monolayer we must consider the high correlation\nbetween the electrons belonging to vanadium to obtain correct results of these\nquantities. We include this correlation employing the Hubbard coupling\nparameter obtained by a linear response method. We found that the system is\nantiferromagnetic and that the quantities studied depend on the magnetic phase\nconsidered. Indirectly, experimental results could validate the theoretical\nvalue of the theoretical Hubbard parameter.",
        "positive": "Dipolar Interaction and Sample Shape Effects on the Hysteresis\n  Properties of 2d Array of Magnetic Nanoparticles: We study the ground state and magnetic hysteresis properties of 2$d$ arrays\n($L^{}_x\\times L^{}_y$) of dipolar interacting magnetic nanoparticles (MNPs) by\nperforming micromagnetic simulations. Our primary interest is to understand the\neffect of sample shape, $\\Theta$- the ratio of the dipolar strength to the\nanisotropy strength, and the direction of the applied field $\\vec{H} =\nH_{o}\\hat{e}^{}_H$ on the ground state and the magnetic hysteresis in an array\nof MNPs. To study the effect of shape of the sample, we have varied the aspect\nratio $A^{}_r=L^{}_y/L^{}_x$ which in turn, is found to induce shape anisotropy\nin the system. Our main observations are: (a) When the dipolar interaction is\nstrong $(\\Theta>1)$, the ground state morphology has in-plane ordering of\nmagnetic moments. (b) The ground state morphology has randomly oriented\nmagnetic moments which is robust with respect to system sizes and $A^{}_r$ for\nweakly interacting MNPs ($\\Theta<1$). (c) Micromagnetic simulations suggests\nthat the dipolar interaction decreases the coercive field $H^{}_c$. (d) The\nremanence magnetization $M^{}_r$ is found to be strongly dependent not only on\nthe strength of dipolar interaction but also on the shape of the sample. (e)\nDue to anisotropic nature of dipolar interaction, a strong effect of shape\nanisotropy is observed when the field is applied along longer axis of the\nsample. The dipolar interaction in such a case induces an effective\nferromagnetic coupling when the aspect ratio is very large. These results are\nof vital importance in high-density recording systems, magneto-impedance\nsensors, etc."
    },
    {
        "anchor": "Mesoscopic theory of defect ordering-disordering transitions in thin\n  oxide films: Ordering of mobile defects in functional materials can give rise to\nfundamentally new phases possessing ferroic and multiferroic functionalities.\nHere we develop the Landau theory for strain induced ordering of defects (e.g.\noxygen vacancies) in thin oxide films, considering both the ordering and\nwavelength of possible instabilities. Using derived analytical expressions for\nthe energies of various defect-ordered states, we calculated and analyzed phase\ndiagrams dependence on the film-substrate mismatch strain, concentration of\ndefects, and Vegard coefficients. Obtained results open possibilities to create\nand control superstructures of ordered defects in thin oxide films by selecting\nthe appropriate substrate and defect concentration.",
        "positive": "Metallic ferroelectricity induced by anisotropic unscreened coulomb\n  interaction in LiOsO3: As the first well-documented example of the ferroelectric metal, LiOsO3 has\nreceived extensive research attention recently. Using density-functional\ncalculations, we perform a systematic study for LiOsO3. We address the\ncontroversy about the depth of the double well in the potential surface, and\npropose that the ferroelectric transition is order-disorder like. Moreover, we\nunambiguously demonstrate that the electric screening in this compound is\nhighly anisotropic, and there is still unscreened dipole-dipole interaction in\none special direction which results in the long range ferroelectric order\ndespite the metallic nature of LiOsO3."
    },
    {
        "anchor": "Pressure-Dependent Layer-by-Layer Oxidation of ZrS2(001) Surface: Understanding oxidation mechanisms of layered semiconducting transition-metal\ndichalcogenide (TMDC) is important not only for controlling native oxide\nformation but also for synthesis of oxide and oxysulfide products. Here,\nreactive molecular dynamics simulations show that oxygen partial pressure\ncontrols not only the ZrS2 oxidation rate but also the oxide morphology and\nquality. We find a transition from layer-by-layer oxidation to\namorphous-oxide-mediated continuous oxidation as the oxidation progresses,\nwhere different pressures selectively expose different oxidation stages within\na given time window. While the kinetics of the fast continuous oxidation stage\nis well described by the conventional Deal-Grove model, the layer-by-layer\noxidation stage is dictated by reactive bond-switching mechanisms. This work\nprovides atomistic details and a potential foundation for rational\npressure-controlled oxidation of broad TMDC materials.",
        "positive": "Tuning the nontrivial topological properties of the Weyl semimetal\n  CeAlSi: In the ferromagnetic Weyl semimetal CeAlSi both space-inversion and\ntime-reversal symmetries are broken. We use external pressure as an effective\ntuning parameter and relate three observations to the presence of a nontrivial\ntopology in its ferromagnetic regime: an exceptional temperature response of\nthe quantum oscillations amplitude, the presence of an anomalous Hall effect\n(AHE), and the existence of an unusual loop Hall effect (LHE). We find a\nsuppression of the AHE and the LHE with increasing pressure, while the Curie\ntemperature is enhanced. The magnetic structure and the electronic bands\nexhibit only a negligible pressure effect suggesting the importance of the\ndomain wall landscape for the topological behavior in CeAlSi."
    },
    {
        "anchor": "Classification of materials with phonon angular momentum and microscopic\n  origin of angular momentum: We group materials into five symmetry classes and determine in which of these\nclasses phonons carry angular momentum in the Brillouin zone, away from a\nhigh-symmetry point, line, or plane. In some materials phonons acquire angular\nmomentum via the forces induced by relative displacements of atoms out of their\nequilibrium positions. However, for other materials, such as ferromagnetic\niron, phonon angular momentum arises from the forces induced by relative\nvelocities of atoms. These effects are driven by the spin-orbit interaction.",
        "positive": "Electric field effect on the thermal conductivity of wurtzite GaN: Gallium nitride (GaN), a wide band-gap semiconductor, has been broadly used\nin power electronic devices due to its high electron mobility and high\nbreakdown voltage. Its relatively high thermal conductivity makes GaN a\nfavorable material for such applications, where heat dissipation is a major\nconcern for device efficiency and long-term stability. However, in GaN-based\ntransistors, where the active region can withstand extremely strong electric\nfields, the field effect on the thermal transport properties has drawn little\nattention so far. In this work, we apply first-principles methods to\ninvestigate phonon properties of wurtzite GaN in the presence of a\nnear-breakdown electric field applied along different crystallographic\ndirections. We find that the electric field changes thermal conductivity\nconsiderably via impacting the bond stiffness and ionicity as well as the\ncrystal symmetry, although it has little effect on phonon dispersions. The\npresence of an out-of-plane electric field increases (decreases) the thermal\nconductivity parallel (perpendicular) to the electric field, which is\nattributed to different changes of the Ga-N bond stiffness and ionicity. When\nan in-plane electric field is applied, the sizable decrease of thermal\nconductivities along all directions is attributed to the crystal symmetry\nbreaking that enhances the phonon-phonon scattering. Our study provides\ninsights into the effect of extreme external electric fields on phonon\ntransport properties in wide-gap semiconductors."
    },
    {
        "anchor": "Mechanism for BCC to HCP Transformation: Generalization of the Burgers\n  Model: Many structural transformations involve a group-nonsubgroup relationship\nbetween the initial and transformed phases, and hence are beyond the purview of\nconventional Landau theory. We utilize a systematic and robust methodology to\ndescribe such reconstructive martensitic transformations by coupling\ngroup-theoretical arguments to first-principles calculations. In this context\nwe (i) use a symmetry-based algorithm to enumerate transformation paths, (ii)\nevaluate the energy barriers along these transformation paths using\nall-electron first principles calculations, (iii) deduce the full set of\nprimary and secondary order parameters for each path to establish the\nappropriate Ginzburg-Landau free-energy functionals, and (iv) for each path,\nidentify special points of the primary order parameter, as a function of local\ndistortions, corresponding to the end product phase. We apply this method to\nthe study of a pressure driven body-centered cubic (bcc) to hexagonal\nclose-packed (hcp) transformation in titanium. We find a generalization of the\nBurgers mechanism, and also find that there is no energy barrier to this\ntransformation. In fact, surprisingly, we also find a region of volumes in\nwhich the intermediate path becomes more stable than either of the end-points\n(bcc or hcp). We therefore predict a new orthorhombic phase for Ti between 51\nand 62 GPa.",
        "positive": "Raman spectra of electrochemically hydrogenated diamond like carbon\n  surface: Raman spectroscopy has been employed to distinguish between the Raman\nspectrum of pristine hydrogenated diamond like carbon (PHDLC) and that of\nelectrochemically hydrogenated diamond like carbon (ECHDLC). The enhancement of\nthe background photoluminescence (PL) in the Raman spectrum and broadening of\nPL spectrum of ECHDLC are identified to be due to increase of sp3 C-H density\nonto the PHDLC surface, during novel electrochemical process of hydrogenation\nof sp2 C=C into sp3 C-H."
    },
    {
        "anchor": "Spin-transfer torques in anti-ferromagnetic metals from first principles: In spite of the absence of a macroscopic magnetic moment, an anti-ferromagnet\nis spin-polarized on an atomic scale. The electric current passing through a\nconducting anti-ferromagnet is polarized as well, leading to spin-transfer\ntorques when the order parameter is textured, such as in anti-ferromagnetic\nnon-collinear spin valves and domain walls. We report a first principles study\non the electronic transport properties of anti-ferromagnetic systems. The\ncurrent-induced spin torques acting on the magnetic moments are comparable with\nthose in conventional ferromagnetic materials, leading to measurable angular\nresistances and current-induced magnetization dynamics. In contrast to\nferromagnets, spin torques in anti-ferromagnets are very nonlocal. The torques\nacting far away from the center of an anti-ferromagnetic domain wall should\nfacilitate current-induced domain wall motion.",
        "positive": "Real-time 3D analysis during electron tomography using tomviz: The demand for high-throughput electron tomography is rapidly increasing in\nbiological and material sciences. However, this 3D imaging technique is\ncomputationally bottlenecked by alignment and reconstruction which runs from\nhours to days. We demonstrate real-time tomography with dynamic 3D tomographic\nvisualization to enable rapid interpretation of specimen structure immediately\nas data is collected on an electron microscope. Using geometrically complex\nchiral nanoparticles, we show volumetric interpretation can begin in less than\n10 minutes and a high quality tomogram is available within 30 minutes. Real\ntime tomography is integrated into tomviz, an open source and cross platform 3D\nanalysis tool that contains intuitive graphical user interfaces (GUI) to enable\nany scientist to characterize biological and material structure in 3D."
    },
    {
        "anchor": "Pairwise Correlations in Layered Close-Packed Structures: Given a description of the stacking statistics of layered close-packed\nstructures in the form of a hidden Markov model, we develop analytical\nexpressions for the pairwise correlation functions between the layers. These\nmay be calculated analytically as explicit functions of model parameters or the\nexpressions may be used as a fast, accurate, and efficient way to obtain\nnumerical values. We present several examples, finding agreement with previous\nwork as well as deriving new relations.",
        "positive": "Novel Multifunctional Materials Based on Oxide Thin Films and Artificial\n  Heteroepitaxial Multilayers: Transition metal oxides show fascinating physical properties such as high\ntemperature superconductivity, ferro- and antiferromagnetism, ferroelectricity\nor even multiferroicity. The enormous progress in oxide thin film technology\nallows us to integrate these materials with semiconducting, normal conducting,\ndielectric or non-linear optical oxides in complex oxide heterostructures,\nproviding the basis for novel multi-functional materials and various device\napplications. Here, we report on the combination of ferromagnetic,\nsemiconducting, metallic, and dielectric materials properties in thin films and\nartificial heterostructures using laser molecular beam epitaxy. We discuss the\nfabrication and characterization of oxide-based ferromagnetic tunnel junctions,\ntransition metal-doped semiconductors, intrinsic multiferroics, and artificial\nferroelectric/ferromagetic heterostructures - the latter allow for the detailed\nstudy of strain effects, forming the basis of spin-mechanics. For\ncharacterization we use X-ray diffraction, SQUID magnetometry, magnetotransport\nmeasurements, and advanced methods of transmission electron microscopy with the\ngoal to correlate macroscopic physical properties with the microstructure of\nthe thin films and heterostructures."
    },
    {
        "anchor": "Specific features of g $\\approx$ 4.3 EPR line behavior in magnetic\n  nanogranular composites: Films of metal-insulator nanogranular composites M$_x$D$_{100-x}$ with\ndifferent composition and percentage of metal and dielectric phases (M = Fe,\nCo, CoFeB; D = Al$_2$O$_3$, SiO$_2$, LiNbO$_3$; x $\\approx$ 15-70 at.%) are\ninvestigated by magnetic resonance in a wide range of frequencies (f = 7-37\nGHz) and temperatures (T = 4.2-360 K). In addition to the usual ferromagnetic\nresonance signal from an array of nanogranules, the experimental spectra\ncontain an additional absorption peak, which we associate with the electron\nparamagnetic resonance (EPR) of Fe and Co ions dispersed in the insulating\nspace between the granules. In contrast to the traditional EPR of Fe and Co\nions in weakly doped non-magnetic matrices, the observed peak demonstrates a\nnumber of unusual properties, which we explain by the presence of magnetic\ninteractions between ions and granules.",
        "positive": "Kinetic Monte Carlo Simulations of dislocations in heteroepitaxial\n  growth: We determine the critical layer thickness for the appearance of misfit\ndislocations as a function of the misfit between the lattice constants of the\nsubstrate and the adsorbate from Kinetic Monte Carlo (KMC) simulations of\nheteroepitaxial growth.\n  To this end, an algorithm is introduced which allows the off-lattice\nsimulation of various phenomena observed in heteroepitaxial growth including\ncritical layer thickness for the appearance of misfit dislocations, or\nself-assembled island formation.\n  The only parameters of the model are deposition flux, temperature and a\npairwise interaction potential between the particles of the system.\n  Our results are compared with a theoretical treatment of the problem and show\ngood agreement with a simple power law."
    },
    {
        "anchor": "Excitonic Instability in Ta$_2$Pd$_3$Te$_5$: By systematic theoretical calculations, we have revealed an excitonic\ninsulator (EI) in a van der Waals layered compound Ta$_2$Pd$_3$Te$_5$.\nFirst-principles calculations show that the monolayer is a nearly zero-gap\nsemiconductor with the modified Becke-Johnson functional. Due to the like\nsymmetry of the band-edge states, the 2D polarization $\\alpha_{2D}$ would be\nfinite as the band gap goes to zero, allowing for the EI state in the compound.\nUsing the first-principles many-body perturbation theory, the $GW$-BSE\ncalculation shows that the exciton binding energy $E_b$ is larger than the\nsingle particle band gap $E_g$, indicating the excitonic instability.\nAdditionally, no structure instability is found in the phonon spectrum of this\nmaterial. Our findings suggest that the Ta$_2$Pd$_3$Te$_5$ monolayer is an\nexcitonic insulator without structure distortion.",
        "positive": "The Phase Diagram of Carbon Dioxide from Correlation Functions and a\n  Many-body Potential: The phase stability and equilibria of carbon dioxide is investigated from 125\n-- 325K and 1 -- 10,000 atm using extensive molecular dynamics (MD) simulations\nand the Two-Phase Thermodynamics (2PT) method. We devise a direct approach for\ncalculating phase diagrams in general, by considering the separate chemical\npotentials of the isolated phase at specific points on the P-T diagram. The\nunique ability of 2PT to accurately and efficiently approximate the entropy and\nGibbs energy of liquids thus allows for assignment of phase boundaries from\nrelatively short ($\\mathrm{\\sim}$ 100ps) MD simulations. We validate our\napproach by calculating the critical properties of the flexible Elementary\nPhysical Model 2 (FEPM2), showing good agreement with previous results. We\nshow, however, that the incorrect description of the short-range Pauli force\nand the lack of molecular charge polarization leads to deviations from\nexperiments at high pressures. We thus develop a many-body, fluctuating charge\nmodel for CO${}_{2}$, termed CO${}_{2}$-Fq, from high level quantum mechanics\n(QM) calculations, that accurately captures the condensed phase vibrational\nproperties of the solid (including the Fermi resonance at 1378 cm${}^{-1}$) as\nwell as the diffusional properties of the liquid, leading to overall excellent\nagreement with experiments over the entire phase diagram. This work provides an\nefficient computational approach for determining phase diagrams of arbitrary\nsystems and underscore the critical role of QM charge reorganization physics in\nmolecular phase stability."
    },
    {
        "anchor": "Twin Domain Structure in Magnetically Doped Topological Insulators: Twin domains are naturally present in the topological insulator \\BiSe{} and\naffect strongly its properties. While studies of its behavior for ideal \\BiSe{}\nstructure exist, little is known about their possible interaction with other\ndefects. Extra information are needed especially for the case of artificial\nperturbation of topological insulator states by magnetic doping, which has\nattracted a lot of attention recently. Employing ab initio calculations based\non layered Green's function formalism, we study the interaction between twin\nplanes in \\BiSe{}. We show the influence of various magnetic and non-magnetic\nchemical defects on the twin plane formation energy and discuss the related\nmodification of their distribution. Furthermore, we examine the change of\ndopants' magnetic properties at sites in the vicinity of a twin plane, and the\ndopants' preference to occupy such sites. Our results suggest that twin planes\nrepel each other at least over distance of $3-4$~nm. However, in the presence\nof magnetic Mn and Fe defects a close TP placement is preferred. Furthermore,\ncalculated twin plane formation energies indicate that in this situation their\nformation becomes suppressed. Finally, we discuss the influence of twin planes\non the surface band gap.",
        "positive": "Observation of Ferromagnetic Clusters in Bi0.125Ca0.875MnO3: The electron doped manganite system, Bi0.125Ca0.875MnO3, exhibits large bulk\nmagnetization of unknown origin. To select amongst possible magnetic ordering\nmodels, we have conducted temperature and magnetic field dependent small-angle\nneutron scattering measurements. Nontrivial spin structure has been revealed.\nFerromagnetic spin clusters form in the antiferromagnetic background when\ntemperature is decreased to Tc~108K. With a further reduction in temperature or\nthe application of external magnetic field, the clusters begin to form in\nlarger numbers, which gives an overall enhancement of magnetization below Tc."
    },
    {
        "anchor": "Ferroelectricity and ferromagnetism in VOI$_2$ monolayer: the role of\n  Dzyaloshinskii-Moriya interaction: Multiferroics with intrinsic ferromagnetism and ferroelectricity are highly\ndesired but rather rare, while most ferroelectric magnets are\nantiferromagnetic. A recent theoretical work [Phys. Rev. B {\\bf 99}, 195434\n(2019)] predicted that oxyhalides VO$X_2$ ($X$: halogen) monolayers are\ntwo-dimensional multiferroics by violating the empirical $d^0$ rule. Most\ninterestingly, the member VOI$_2$ are predicted to exhibit spontaneous\nferromagnetism and ferroelectricity. In this work, we extend the previous study\non the structure and magnetism of VOI$_2$ monolayer by using density functional\ntheory and Monte Carlo simulation. The presence of the heavy element iodine\nwith a strong spin-orbit coupling leads an effective Dzyaloshinskii-Moriya\ninteraction in the polar structure, which favors a short-period spiral a\nmagnetic structure.. Another interesting result is that the on-site Coulomb\ninteraction can strongly suppress the polar distortion thus leading to a\nferromagnetic metallic state. Therefore, the VOI2 monolayer is either a\nferroelectric insulator with spiral magnetism or a ferromagnetic metal, instead\nof a ferromagnetic ferroelectric system. Our study highlights the key physical\nrole of the Dzyaloshinskii-Moriya interaction.",
        "positive": "Prediction of Room Temperature High Thermoelectric Performance in n-type\n  La(Ru,Rh)4Sb12: First principles calculations are used to investigate the band structure and\nthe transport related properties of unfilled and filled 4d skutterudite\nantimonides. The calculations show that, while RhSb3 and p-type La(Rh,Ru)4Sb12\nare unfavorable for thermoelectric application, n-type La(Rh,Ru)4Sb12 is very\nlikely a high figure of merit thermoelectric material in the important\ntemperature range 150-300 K."
    },
    {
        "anchor": "Augmenting the spin properties of shallow implanted NV-centers by\n  CVD-overgrowth: The controlled scaling of diamond defect center based quantum registers\nrelies on the ability to position NVs with high spatial resolution. Using ion\nimplantation, shallow (< 10 nm) NVs can be placed with accuracy below 20nm, but\ngenerally show reduced spin properties compared to bulk NVs. We demonstrate the\naugmentation of spin properties for shallow implanted NV centers using an\novergrowth technique. An increase of the coherence times up to an order of\nmagnitude (T_2 = 250 \\mu s) was achieved. Dynamic decoupling of defects spins\nachieves ms decoherence times. The study marks a further step towards achieving\nstrong coupling among defects positioned with nm precision.",
        "positive": "Nonlinear spectroscopy of excitonic states in transition metal\n  dichalcogenides: Second-harmonic generation (SHG) is a well-known nonlinear spectroscopy\nmethod to probe electronic structure, specifically, in transition metal\ndichalcogenide (TMDC) monolayers. This work investigates the nonlinear dynamics\nof a strongly excited TMDC monolayer by solving the time evolution equations\nfor the density matrix. It is shown that the presence of excitons qualitatively\nchanges the nonlinear dynamics leading, in particular, to a huge enhancement of\nthe nonlinear signal as a function of the dielectric environment. It is also\nshown that the SHG polarization angular diagram and its dependence on the\ndriving strength are very sensitive to the type of exciton state. This\nsensitivity suggests that SHG spectroscopy is a convenient tool for analyzing\nthe fine structure of excitonic states."
    },
    {
        "anchor": "THz spin-wave excitations in the transverse conical phase of BiFeO$_3$: Although BiFeO$_3$ is one of the most studied multiferroic materials, recent\nmagnetization and neutron scattering studies have revealed a new magnetic phase\nin this compound - the transverse conical phase. To study the collective spin\nexcitations of this phase, we performed THz spectroscopy in magnetic fields up\nto 17 T at and above room temperature. We observed five spin-wave branches in\nthe magnetic phase with long wavelength conical modulation. Using a numerical\nspin dynamics model we found two kinds of excitations with magnetic moments\noscillating either along or perpendicular to the static fields. Remarkably, we\ndetected strong directional dichroism, an optical manifestation of the\nmagnetoelectric effect, for two spin-wave modes of the conical phase. According\nto our experiments, the stability of the conical state is sensitive to the\nmagnetic field history and it can become (meta)stable at or close to zero\nmagnetic field, which may allow exploiting its magnetoelectric properties at\nroom temperature.",
        "positive": "A review and outlook on anionic and cationic redox in Ni-, Li- and\n  Mn-rich layered oxides LiMeO2 (Me = Li, Ni, Co, Mn): The present work reviews the charge compensation in Ni based layered oxides\n(LiNi1-xMexO2 with x <= 0.2, Me = Co, Mn, space group R-3m) relating\nperformance parameters to changes in the electronic and crystallographic\nstructure of the cathode materials. Upon charge and discharge two fundamentally\ndifferent redox mechanisms are observed: At low and medium states of charge\n(SOCs) charge compensation takes mainly place at oxygen sites while electron\ndensity is shifted from the oxygen lattice to nickel (formation of sigma\nbonds). At high SOCs the shift of electron density from the transition metals\nto oxygen (formation of pi bonds) enables an additional redox process but also\noxygen release from the transition metal host structure and subsequent\ndetrimental reactions. Depending on the Ni:Co:Mn content, both processes lead\nto characteristic features in the voltage profile of the cathode materials and\nperformance parameters like the capacity, the cycling stability and the open\ncell voltage become a function of the composition."
    },
    {
        "anchor": "Prediction of Silicate Glasses' Stiffness by High-Throughput Molecular\n  Dynamics Simulations and Machine Learning: The development by machine learning of models predicting materials'\nproperties usually requires the use of a large number of consistent data for\ntraining. However, quality experimental datasets are not always available or\nself-consistent. Here, as an alternative route, we combine machine learning\nwith high-throughput molecular dynamics simulations to predict the Young's\nmodulus of silicate glasses. We demonstrate that this combined approach offers\nexcellent predictions over the entire compositional domain. By comparing the\nperformance of select machine learning algorithms, we discuss the nature of the\nbalance between accuracy, simplicity, and interpretability in machine learning.",
        "positive": "Spin pumping in strongly coupled magnon-photon systems: We experimentally investigate magnon-polaritons, arising in ferrimagnetic\nresonance experiments in a microwave cavity with a tuneable quality factor. To\nhis end, we simultaneously measure the electrically detected spin pumping\nsignal and microwave reflection (the ferrimagnetic resonance signal) of a\nyttrium iron garnet (YIG) / platinum (Pt) bilayer in the microwave cavity. The\ncoupling strength of the fundamental magnetic resonance mode and the cavity is\ndetermined from the microwave reflection data. All features of the magnetic\nresonance spectra predicted by first principle calculations and an input-output\nformalism agree with our experimental observations. By changing the decay rate\nof the cavity at constant magnon-photon coupling rate, we experimentally tune\nin and out of the strong coupling regime and successfully model the\ncorresponding change of the spin pumping signal. Furthermore, we observe the\ncoupling and spin pumping of several spin wave modes and provide a quantitative\nanalysis of their coupling rates to the cavity."
    },
    {
        "anchor": "Enhancing the Accuracy of Density Functional Tight Binding Models\n  Through ChIMES Many-body Interaction Potentials: Semi-empirical quantum models such as Density Functional Tight Binding (DFTB)\nare attractive methods for obtaining quantum simulation data at longer time and\nlength scales than possible with standard approaches. However, application of\nthese models can require lengthy effort due to the lack of a systematic\napproach for their development. In this work, we discuss use of the Chebyshev\nInteraction Model for Efficient Simulation (ChIMES) to create rapidly\nparameterized DFTB models which exhibit strong transferability due to the\ninclusion of many-body interactions that might otherwise be inaccurate. We\napply our modeling approach to silicon polymorphs and review previous work on\ntitanium hydride. We also review creation of a general purpose DFTB/ChIMES\nmodel for organic molecules and compounds that approaches hybrid functional and\ncoupled cluster accuracy with two orders of magnitude fewer parameters than\nsimilar neural network approaches. In all cases, DFTB/ChIMES yields similar\naccuracy to the underlying quantum method with orders of magnitude improvement\nin computational cost. Our developments provide a way to create computationally\nefficient and highly accurate simulations over varying extreme thermodynamic\nconditions, where physical and chemical properties can be difficult to\ninterrogate directly and there is historically a significant reliance on\ntheoretical approaches for interpretation and validation of experimental\nresults.",
        "positive": "Experimental determination and modelling of volume shrinkage in curing\n  thermosets: This work deals with the characterisation and modelling of the curing process\nand its associated volume changes of an epoxy based thermoset resin.\nMeasurements from differential scanning calorimetry (DSC) define the progress\nof the chemical reaction. The related thermochemical volume changes are\nrecorded by an especially constructed experimental setup based on Archimedes\nprinciple. Information on measuring procedure and data processing are provided.\nThis includes investigations on compensation of environmental influences,\nlong-term stability and resolution. With the aim of simulating the adhesives\ncuring process, constitutive models representing the reaction kinetics and\nthermochemical volume changes are presented and the model parameters are\nidentified."
    },
    {
        "anchor": "Charge distribution across capped and uncapped infinite-layer neodymium\n  nickelate thin films: Charge ordering (CO) phenomena have been widely debated in\nstrongly-correlated electron systems mainly regarding their role in\nhigh-temperature superconductivity. Here, we elucidate the structural and\ncharge distribution in NdNiO$_{2}$ thin films prepared with and without capping\nlayers, and characterized by the absence and presence of CO. Our\nmicrostructural and spectroscopic analysis was done by scanning transmission\nelectron microscopy-electron energy loss spectroscopy (STEM-EELS) and hard\nx-ray photoemission spectroscopy (HAXPES). Capped samples show Ni$^{1+}$, with\nan out-of-plane (o-o-p) lattice parameter of around 3.30 angstroms indicating\ngood stabilization of the infinite-layer structure. Bulk-sensitive HAXPES on\nNi-2p shows weak satellite feature indicating large charge-transfer energy. The\nuncapped samples evidence an increase of the o-o-p parameter up to 3.65\nangstroms on the thin-film top, and spectroscopies show signatures of higher\nvalence in this region (towards Ni$^{2+}$). Here, 4D-STEM demonstrates (3,0,3)\noriented stripes which emerge from partially occupied apical oxygen. Those\nstripes form quasi-2D coherent domains viewed as rods in the reciprocal space\nwith $\\Delta\\text{q}_{z} \\approx 0.24$ r.l.u. extension located at Q = ($\\pm\n\\frac{1}{3},0,\\pm \\frac{1}{3}$) r.l.u. and Q = ($\\pm \\frac{2}{3},0,\\pm\n\\frac{2}{3}$) r.l.u. The stripes associated with oxygen re-intercalation\nconcomitant with hole doping suggests a possible link to the previously\nreported CO in infinite-layer nickelate thin films.",
        "positive": "Generalized Elliott-Yafet spin-relaxation time for arbitrary spin mixing: We extend our recent result for the spin-relaxation time due to acoustic\nelectron-phonon scattering in degenerate bands with spin mixing [New J. Phys.\n18, 023012 (2015)] to include interactions with optical phonons, and present a\nnumerical evaluation of the spin-relaxation time for intraband hole-phonon\nscattering in the heavy-hole (HH) bands of bulk GaAs. Comparing our computed\nspin-relaxation times to the conventional Elliott-Yafet result quantitatively\ndemonstrates that the latter underestimates the spin-relaxation time because it\ndoes not correctly describe how electron-phonon interactions change the\n(vector) spin expectation value of the single-particle states. We show that the\nconventional Elliott-Yafet spin relaxation time is a special case of our result\nfor weak spin mixing."
    },
    {
        "anchor": "Structural Phase Transitions in SrTiO3 from Deep Potential Molecular\n  Dynamics: Strontium titanate (SrTiO3) is regarded as an essential material for oxide\nelectronics. One of its many remarkable features is subtle structural phase\ntransition, driven by antiferrodistortive lattice mode, from a high-temperature\ncubic phase to a low-temperature tetragonal phase. Classical molecular dynamics\n(MD) simulation is an efficient technique to reveal atomistic features of phase\ntransition, but its application is often limited by the accuracy of empirical\ninteratomic potentials. Here, we develop an accurate deep potential (DP) model\nof SrTiO3 based on a machine learning method using data from first-principles\ndensity functional theory (DFT) calculations. The DP model has DFT-level\naccuracy, capable of performing efficient MD simulations and accurate property\npredictions. Using the DP model, we investigate the temperature-driven\ncubic-to-tetragonal phase transition and construct the in-plane biaxial\nstrain-temperature phase diagram of SrTiO3. The simulations demonstrate that\nstrain-induced ferroelectric phase is characterized by two order parameters,\nferroelectric distortion and antiferrodistortion, and the ferroelectric phase\ntransition has both displacive and order-disorder characters. This works lays\nthe foundation for the development of accurate DP models of other complex\nperovskite materials.",
        "positive": "Resonant x-ray scattering reveals possible disappearance of magnetic\n  order under hydrostatic pressure in the Kitaev candidate\n  $\u03b3$-Li$_2$IrO$_3$: Honeycomb iridates such as $\\gamma$-Li$_2$IrO$_3$ are argued to realize\nKitaev spin-anisotropic magnetic exchange, along with Heisenberg and possibly\nother couplings. While systems with pure Kitaev interactions are candidates to\nrealize a quantum spin liquid ground state, in $\\gamma$-Li$_2$IrO$_3$ it has\nbeen shown that the balance of magnetic interactions leads to the\nincommensurate spiral spin order at ambient pressure below 38 K. We study the\nfragility of this state in single crystals of $\\gamma$-Li$_2$IrO$_3$ using\nresonant x-ray scattering (RXS) under applied hydrostatic pressures of up to\n3.0 GPa. RXS is a direct probe of the underlying electronic order, and we\nobserve the abrupt disappearance of the $q$=(0.57, 0, 0) spiral order at a\ncritical pressure $P_c = 1.5\\ $GPa with no accompanying change in the symmetry\nof the lattice. This dramatic disappearance is in stark contrast with recent\nstudies of $\\beta$-Li$_2$IrO$_3$ that show continuous suppression of the spiral\norder in magnetic field; under pressure, a new and possibly nonmagnetic ground\nstate emerges."
    },
    {
        "anchor": "An electron spin injection driven, paramagnetic solid-state MASER device: In response to an external, microwave-frequency magnetic field, a\nparamagnetic medium will absorb energy from the field that drives the\nmagnetization dynamics. Here we describe a new process by which an external\nspin injection source, when combined with the microwave field spin-pumping, can\ndrive the paramagnetic medium from one that absorbs microwave energy to one\nthat emits microwave energy. We derive a simple condition for the crossover\nfrom absorptive to emissive behavior. Based on this process, we propose a spin\ninjection-driven paramagnetic MASER device.",
        "positive": "Precessional dynamics of elemental moments in a ferromagnetic alloy: We demonstrate an element-specific measurement of magnetization precession in\na metallic ferromagnetic alloy, separating Ni and Fe moment motion in Ni81Fe19.\nPump-probe X-ray magnetic circular dichroism (XMCD), synchronized with short\nmagnetic field pulses, is used to measure free magnetization oscillations up to\n2.6 GHz with elemental specificity and a rotational resolution of < 2 deg.\nMagnetic moments residing on Ni sites and Fe sites in a Ni81Fe19(50nm) thin\nfilm are found to precess together at all frequencies, coupled in phase within\ninstrumental resolution of 90 ps."
    },
    {
        "anchor": "Magnetoelectric domains and their switching mechanism in a Y-type\n  hexaferrite: By employing resonant X-ray microdiffraction, we image the magnetisation and\nmagnetic polarity domains of the Y-type hexaferrite\nBa$_{0.5}$Sr$_{1.5}$Mg$_2$Fe$_{12}$O$_{22}$. We show that the magnetic polarity\ndomain structure can be controlled by both magnetic and electric fields, and\nthat full inversion of these domains can be achieved simply by reversal of an\napplied magnetic field in the absence of an electric field bias. Furthermore,\nwe demonstrate that the diffraction intensity measured in different X-ray\npolarisation channels cannot be reproduced by the accepted model for the polar\nmagnetic structure, known as the 2-fan transverse conical (TC) model. We\npropose a modification to this model, which achieves good quantitative\nagreement with all of our data. We show that the deviations from the TC model\nare large, and may be the result of an internal magnetic chirality, most likely\ninherited from the parent helical (non-polar) phase.",
        "positive": "Cylindrical void growth vs. grain fragmentation in FCC single crystals:\n  CPFEM study for two types of loading conditions: The crystal plasticity finite element method (CPFEM) is used to investigate\nthe coupling between the cylindrical void growth or collapse and grain\nrefinement in face-centered cubic (FCC) single crystals. A 2D plane strain\nmodel with one void is used. The effect of the initial lattice orientation,\nsimilarities, and differences between stress- and strain-driven loading\nscenarios are explored. To this end, boundary conditions are enforced in two\ndifferent ways. The first one is based on maintaining constant in-plane stress\nbiaxiality via a dedicated truss element, while the second one is imposing a\nconstant displacement biaxiality factor. Uniaxial and biaxial loading cases are\nstudied. For the uniaxial loading case a special configuration, which enforces\nan equivalent pattern of plastic deformation in the pristine crystal, is\nselected in order to investigate the mutual interactions between the evolving\nvoid and the developed lattice rotation heterogeneity. Next, biaxial loading\ncases are considered for three crystal orientations, one of which is not\nsymmetric with respect to loading directions. It is analysed how stress or\nstrain biaxility factors and initial lattice orientation influence the void\nevolution in terms of its size and shape. Moreover, the consequences of\nvariations in the resulting heterogeneity of lattice rotation are studied in\nthe context of the grain refinement phenomenon accompanying the void evolution.\nScenarios that may lead to more advanced grain fragmentation are identified."
    },
    {
        "anchor": "Steps towards a Dislocation Ontology for Crystalline Materials: The field of Materials Science is concerned with, e.g., properties and\nperformance of materials. An important class of materials are crystalline\nmaterials that usually contain ``dislocations'' -- a line-like defect type.\nDislocation decisively determine many important materials properties. Over the\npast decades, significant effort was put into understanding dislocation\nbehavior across different length scales both with experimental characterization\ntechniques as well as with simulations. However, for describing such\ndislocation structures there is still a lack of a common standard to represent\nand to connect dislocation domain knowledge across different but related\ncommunities. An ontology offers a common foundation to enable knowledge\nrepresentation and data interoperability, which are important components to\nestablish a ``digital twin''. This paper outlines the first steps towards the\ndesign of an ontology in the dislocation domain and shows a connection with the\nalready existing ontologies in the materials science and engineering domain.",
        "positive": "Effect of metal dopant on structural and magnetic properties of ZnO\n  nanoparticles: Zn1-xRxO (R = Li, Mg, Cr, Mn, Fe and Cd) were obtained by using\nco-precipitation synthesis technique with constant weight percent of 3% from R\nions. The phase composition, crystal structure, morphology, Density Functional\nTheory (DFT), and, magnetic properties were examined to comprehend the\ninfluence of Zn2+ partial substitution with R ions. X-ray diffraction shows\nthat the ZnO lattice parameters were slightly affected by R doping and the\ndoped sample crystallinity is enhanced. Our results show that introducing Cr,\nMn and Fe along with Mg into ZnO induces a clear magnetic moment without any\napparent distortion in the structural morphology. The spatial configuration of\ndopant atoms is determined from first-principles calculations, giving a better\nunderstanding of the position of the dopant atom responsible for the magnetism.\nThe magnetic moments obtained from our calculations are 3.67, 5.0, and 4.33\n{\\mu}B per dopant atom for Cr, Mn, and Fe, respectively, which agree with the\nexperimental values. While Cr and Fe tend to form clusters, Mn has more\npropensity to remain evenly distributed within the system, avoiding\ncluster-derived magnetism."
    },
    {
        "anchor": "Electronic structure of barium titanate : an abinitio DFT study: First principle calculations were performed to study the ground state\nelectronic properties of Barium titanate within the density functional theory\n(DFT). In our DFT computations, we used Vosko-Wilk-Nusair correlation energy\nfunctional and generalized gradient approximation (GGA) exchange and\ncorrelation energy functional as suggested by Perdew and Wang (PWGGA). The band\nstructure, total density of states (DOS) and partial DOS have been\nsystematically conducted to investigate the electronic configuration of this\nprototype ferroelectric perovskits compound. The band gap was 1.92 eV within\nour approach, and the quasi-flat band at -17 eV and -10 eV were attributed to\nthe O 2s and Ba 5p states respectively, which was in good agreement with the\ncorresponding total DOS and partial DOS. From the DOS investigation, it can be\nseen that the Ti eg state intended to interact with the oxygen octahedral\norbitals to form the p-d hybridization. Moreover the strong p-d overlap and\nbonding can be observed in the electronic density redistribution along the\ndifferent crystalline planes with respect to the corresponding space group, and\nthe electronic isodense have been shown along the (001), (100), (110) and (111)\ncrystal planes. From these electronic density maps, the strong bonding between\nTi and O atoms can even be observed in the (111) crystalline plane.",
        "positive": "Current-induced magnetization switching in a chemically disordered A1\n  CoPt single layer: We report the first demonstration of the current-induced magnetization\nswitching in a perpendicularly magnetized A1 CoPt single layer. We show that\ngood perpendicular magnetic anisotropy can be obtained in a wide composition\nrange of the A1 Co1-xPtx single layers, which allows to fabricate\nperpendicularly magnetized CoPt single layer with composition gradient to break\nthe inversion symmetry of the structure. By fabricating the gradient CoPt\nsingle layer, we have evaluated the SOT efficiency and successfully realized\nthe SOT-induced magnetization switching. Our study provides an approach to\nrealize the current-induced magnetization in the ferromagnetic single layers\nwithout attaching SOT source materials."
    },
    {
        "anchor": "Frequency and power dependence of spin-current emission by spin pumping\n  in a thin film YIG/Pt system: This paper presents the frequency dependence of the spin current emission in\na hybrid ferrimagnetic insulator/normal metal system. The system is based on a\nferrimagnetic insulating thin film of Yttrium Iron Garnet (YIG, 200 nm) grown\nby liquid-phase-epitaxy (LPE) coupled with a normal metal with a strong\nspin-orbit coupling (Pt, 15 nm). The YIG layer presents an isotropic behaviour\nof the magnetization in the plane, a small linewidth, and a roughness lower\nthan 0.4 nm. Here we discuss how the voltage signal from the spin current\ndetector depends on the frequency [0.6 - 7 GHz], the microwave power, Pin, [1 -\n70 mW], and the in-plane static magnetic field. A strong enhancement of the\nspin current emission is observed at low frequencies, showing the appearance of\nnon-linear phenomena.",
        "positive": "Interdiffusion between gadolinia doped ceria and yttria stabilized\n  zirconia in solid oxide fuel cells: experimental investigation and kinetic\n  modeling: Interdiffusion between the yttria stabilized zirconia (YSZ) electrolyte and\nthe gadolinia doped ceria (CGO) barrier layer is one of the major causes to the\ndegradation of solid oxide fuel cells (SOFCs). We present in this work\nexperimental investigations on CGO-YSZ bi-layer electrolyte sintered at 1250 C\nor 1315 C and element transport as a function of sintering temperature and\ndwelling time. In order to quantitatively simulate the experimental\nobservations, the CALPHAD-type thermodynamic assessment of the CGO-YSZ system\nis performed by simplifying the system to a CeO2-ZrO2 quasi-binary system, and\nthe kinetic descriptions (atomic mobilities) are constructed based on critical\nreview of literature data. The CGO-YSZ interdiffusion is then modeled with the\nDICTRA software and the simulation results are compared with the experimental\ndata under different sintering or long-term operating conditions. The\ncorresponding ohmic resistance of the bi-layer electrolyte is predicted based\non the simulated concentration profile. The results implies that the\ninterdiffusion across the CGO-YSZ interface happens mainly during sintering at\nhigh temperature, while during long-term operation at relatively lower\ntemperature the impact of interdiffusion on cell degradation is negligible."
    },
    {
        "anchor": "A primitive machine learning tool for the mechanical property prediction\n  of multiple principal element alloys: Multi-principal element alloys (MPEAs) are produced by combining metallic\nelements in what is a diverse range of proportions. MPEAs reported to date have\nrevealed promising performance due to their exceptional mechanical properties.\nTraining a machine learning (ML) model on known performance data is a\nreasonable method to rationalise the complexity of composition dependent\nmechanical properties of MPEAs. This study utilises data from a specifically\ncurated dataset, that contains information regarding six mechanical properties\nof MPEAs. A parser tool was introduced to convert chemical composition of\nalloys into the input format of the ML models, and a number of ML models were\napplied. Finally, Gradio was used to visualise the ML model predictions and to\ncreate a user-interactive interface. The ML model presented is an initial\nprimitive model (as it does not factor in aspects such as MPEA production and\nprocessing route), however serves as a an initial user tool, whilst also\nproviding a workflow for other researchers.",
        "positive": "Terahertz Emission From an Exchange-Coupled Synthetic Antiferromagnet: We report on terahertz emission from FeMnPt/Ru/FeMnPt and\nPt/CoFeB/Ru/CoFeB/Pt synthetic antiferromagnet (SAF) structures upon\nirradiation by a femtosecond laser; the former is via the anomalous Hall\neffect, whereas the latter is through the inverse spin Hall effect. The\nantiparallel alignment of the two ferromagnetic layers leads to a terahertz\nemission peak amplitude that is almost double that for a corresponding\nsingle-layer or bilayer emitter with the same equivalent thickness. In\naddition, we demonstrate by both simulation and experiment that terahertz\nemission provides a powerful tool to probe the magnetization reversal processes\nof individual ferromagnetic layers in a SAF structure, as the terahertz signal\nis proportional to the vector difference of the magnetizations of the two\nferromagnetic layers."
    },
    {
        "anchor": "First principles investigation of thermal conductivity in Magnesium\n  Selenide(MgSe) with different crystalline phase: Magnesium Selenide (MgSe) is a wide bandgap semiconductor with applications\nin optoelectronics and energy conversion technologies. Understanding thermal\nconductivity (k) of MgSe is critical for optimum design of thermal transport in\nthese applications. In this work, we report the temperature and length\ndependence lattice thermal conductivity of magnesium selenide (MgSe) with\ndifferent crystallographic phases; zincblende, rocksalt, wurtzite and nickel\narsenic, using first principles computations. Computations reveal significant\ndifferences in thermal conductivity (k) of MgSe for different phases. The\nobserved trend in thermal conductivities is : kNiAs < krocksalt < kwurtzite <\nkzincblende. Our first principles calculations show a room temperature low k of\n4.5 Wm-1K-1 for the NiAs phase and a high k of 20.4 W/mK for wurtzite phase.\nThese differences are explained in terms of a phonon band gap in the\nvibrational spectra of zincblende and wurtzite phases, which suppresses\nscattering of acoustic phonons, leading to high phonon lifetimes.",
        "positive": "Electrocaloric response in Lanthanum-modified lead zirconate titanate\n  ceramics: Recent findings of a large electrocaloric (EC) effect in polymeric and\ninorganic ferroelectric materials open a potential possibility of development\nof solid-state cooling or heating devices of new generation with better energy\nefficiency that may be less harmful for the environment. We investigate by\nusing direct measurements, the temperature and electric field dependence of the\nelectrocaloric response in Pb1-xLax(ZryTi1-y)1-x/4O3 bulk ceramics (PLZT) with\nx=0.06 and 0.12. Here, the properties of the EC response were probed in a part\nof the PLZT composition phase diagram with low y=0.40 composition, in which the\nEC effect was not previously studied. Measurement results show the existence of\nthe sizeable EC response in 12/40/60 PLZT sample with the EC temperature change\n({\\Delta}TEC) of 2.92 K at 430 K and 80 kV/cm. This value exceeds previously\nobtained {\\Delta}TEC values in relaxor ferroelectric x/65/35 PLZT compositions\nand rivaling the best EC response in lead magnesium niobate-lead titanate\nceramics. The electrocaloric responsivity ({\\Delta}T/{\\Delta}E) value of\n0.41x10-6 Km/V determined at a lower electric field of 20 kV/cm and 410 K is\ncomparable to those observed in other perovskite ferroelectrics."
    },
    {
        "anchor": "Initial stages of the graphite-SiC(0001) interface formation studied by\n  photoelectron spectroscopy: Graphitization of the 6H-SiC(0001) surface as a function of annealing\ntemperature has been studied by ARPES, high resolution XPS, and LEED. For the\ninitial stage of graphitization - the 6root3 reconstructed surface - we observe\nsigma-bands characteristic of graphitic sp2-bonded carbon. The pi-bands are\nmodified by the interaction with the substrate. C1s core level spectra indicate\nthat this layer consists of two inequivalent types of carbon atoms. The next\nlayer of graphite (graphene) formed on top of the 6root3 surface at\nTA=1250-1300 degree C has an unperturbed electronic structure. The annealing at\nhigher temperatures results in the formation of a multilayer graphite film. It\nis shown that the atomic arrangement of the interface between graphite and the\nSiC(0001) surface is practically identical to that of the 6root3 reconstructed\nlayer.",
        "positive": "Dynamic symmetry breaking in chiral magnetic systems: The Dzyaloshinskii-Moriya interaction (DMI) in magnetic systems stabilizes\nspin textures with preferred chirality, applicable to next-generation memory\nand computing architectures. In perpendicularly magnetized\nheavy-metal/ferromagnet films, the interfacial DMI originating from structural\ninversion asymmetry and strong spin-orbit coupling favors chiral N\\'eel-type\ndomain walls (DWs) whose energetics and mobility remain at issue. Here, we\ncharacterize a new effect in which domains expand unidirectionally in response\nto a combination of out-of-plane and in-plane magnetic fields, with the growth\ndirection controlled by the in-plane field strength. These growth\ndirectionalities and symmetries with applied fields cannot be understood from\nstatic treatments alone. We theoretically demonstrate that perpendicular field\ntorques stabilize steady-state magnetization profiles highly asymmetric in\nelastic energy, resulting in a dynamic symmetry breaking consistent with the\nexperimental findings. This phenomenon sheds light on the mechanisms governing\nthe dynamics of N\\'eel-type DWs and expands the utility of field-driven DW\nmotion to probe and control chiral DWs."
    },
    {
        "anchor": "Symmetric carbon tetramers forming chemically stable spin qubits in hBN: Point defect quantum bits in semiconductors have the potential to\nrevolutionize sensing at atomic scales. Currently, vacancy related defects,\nsuch as the NV center in diamond and the VB$^-$ in hexagonal boron nitride\n(hBN), are at the forefront of high spatial resolution and low dimensional\nsensing. On the other hand, vacancies' reactive nature and instability at the\nsurface limit further developments. Here, we study the symmetric carbon\ntetramers in hBN and propose them as a chemically stable spin qubit for sensing\nin low dimensions. We utilize periodic-DFT and quantum chemistry approaches to\nreliably and accurately predict the electronic, optical, and spin properties of\nthe studied defect. We show that the nitrogen centered symmetric carbon\ntetramer gives rise to spin state dependent optical signals with strain\nsensitive intersystem crossing rates. Furthermore, the weak hyperfine coupling\nof the defect to their spin environments results in a reduced electron spin\nresonance linewidth that may enhance sensitivity.",
        "positive": "Computational Insights into Electronic Excitations, Spin-Orbit Coupling\n  Effects, and Spin Decoherence in Cr(IV)-based Molecular Qubits: The great success of point defects and dopants in semiconductors for quantum\ninformation processing has invigorated a search for molecules with analogous\nproperties. Flexibility and tunability of desired properties in a large\nchemical space have great advantages over solid-state systems. The properties\nanalogous to point defects were demonstrated in Cr(IV)-based molecular family,\nCr(IV)(aryl)$_4$, where the electronic spin states were optically initialized,\nread out, and controlled. Despite this kick-start, there is still a large room\nfor enhancing properties crucial for molecular qubits. Here we provide\ncomputational insights into key properties of the Cr(IV)-based molecules aimed\nat assisting chemical design of efficient molecular qubits. Using the\nmultireference ab-initio methods, we investigate the electronic states of\nCr(IV)(aryl)$_4$ molecules with slightly different ligands, showing that the\nzero-phonon line energies agree with the experiment, and that the excited\nspin-triplet and spin-singlet states are highly sensitive to small chemical\nperturbations. By adding spin-orbit interaction, we find that the sign of the\nuniaxial zero-field splitting (ZFS) parameter is negative for all considered\nmolecules, and discuss optically-induced spin initialization via non-radiative\nintersystem crossing. We quantify (super)hyperfine coupling to the $^{53}$Cr\nnuclear spin and to the $^{13}$C and $^1$H nuclear spins, and we discuss\nelectron spin decoherence. We show that the splitting or broadening of the\nelectronic spin sub-levels due to superhyperfine interaction with $^1$H nuclear\nspins decreases by an order of magnitude when the molecules have a substantial\ntransverse ZFS parameter."
    },
    {
        "anchor": "Emergent quantum confinement at topological insulator surfaces: Bismuth-chalchogenides are model examples of three-dimensional topological\ninsulators. Their ideal bulk-truncated surface hosts a single spin-helical\nsurface state, which is the simplest possible surface electronic structure\nallowed by their non-trivial $\\mathbb{Z}_2$ topology. They are therefore widely\nregarded ideal templates to realize the predicted exotic phenomena and\napplications of this topological surface state. However, real surfaces of such\ncompounds, even if kept in ultra-high vacuum, rapidly develop a much more\ncomplex electronic structure whose origin and properties have proved\ncontroversial. Here, we demonstrate that a conceptually simple model,\nimplementing a semiconductor-like band bending in a parameter-free\ntight-binding supercell calculation, can quantitatively explain the entire\nmeasured hierarchy of electronic states. In combination with circular dichroism\nin angle-resolved photoemission (ARPES) experiments, we further uncover a rich\nthree-dimensional spin texture of this surface electronic system, resulting\nfrom the non-trivial topology of the bulk band structure. Moreover, our study\nreveals how the full surface-bulk connectivity in topological insulators is\nmodified by quantum confinement.",
        "positive": "2D materials coated plasmonic structures for SERS applications: Two-dimensional (2D) materials, such as graphene and hexagonal boron nitride,\nare new kind of materials that can serve as substrates for surface enhanced\nRaman spectroscopy (SERS). When combined with traditional metallic plasmonic\nstructures, the hybrid 2D materials/metal SERS platform brings extra benefits,\nincluding higher SERS enhancement factors, oxidation protection of metal\nsurface, and protection of molecules from photo-induced damage. This\nperspective gives an overview of recent progress in 2D materials coated\nplasmonic structure in SERS application. This paper focuses on the fabrication\nof the hybrid 2D materials/metal SERS platform and their applications for Raman\nenhancement."
    },
    {
        "anchor": "Dopant incorporation site in sodium cobaltate's host lattice: A critical\n  factor for thermoelectric performance: $Na_xCoO_2$ that comprises of alternating Na and $CoO_2$ layers has exotic\nmagnetic and thermoelectric properties that could favorably be manipulated by\nadding dopants or varying Na concentration. In this work, we investigated the\nstructural and electronic properties of Sr and Sb doped $Na_xCoO_2$ ($x$ =\n0.50; 0.625; 0.75 and 0.875) through comprehensive density functional\ncalculations. We found that Sr dopants always occupy a site in the Na layer\nwhile Sb dopants always substitute a Co ion in the host lattice regardless of\nNa concentration. This conclusion withstood when either generalized gradient\napproximation (GGA) or GGA+$U$ method was used. By residing on the Na layer, Sr\ndopants create charge and mass inertia against the liquid like Na layer,\ntherefore, improving the crystallinity and decreasing the electrical\nresistivity through better carrier mobility. On the other hand, by substituting\nCo ions, Sb dopants reduce the electrical conductivity and therefore decrease\nthe Seebeck coefficient.",
        "positive": "Probing carrier dynamics in photo-excited graphene with time-resolved\n  ARPES: The dynamics of photo-generated electron-hole pairs in solids are dictated by\nmany-body interactions such as electron-electron and electron-phonon\nscattering. Hence, understanding and controlling these scattering channels is\ncrucial for many optoelectronic applications, ranging from light harvesting to\noptical amplification. Here we measure the formation and relaxation of the\nphoto-generated non-thermal carrier distribution in monolayer graphene with\ntime- and angle-resolved photoemission spectroscopy. Using sub 10fs pulses we\nidentify impact ionization as the primary scattering channel, which dominates\nthe dynamics for the first 25fs after photo-excitation. Auger recombination is\nfound to set in once the carriers have accumulated at the Dirac point with time\nscales between 100 and 250fs, depending on the number of non-thermal carriers.\nOur observations help in gauging graphene's potential as a solar cell and\nTeraHertz lasing material."
    },
    {
        "anchor": "Ferrimagnetism and spontaneous ordering of transition-metals in\n  La2CrFeO6 double-perovskite films: We report on atomic ordering of B-site transition-metals and magnetic\nproperties of epitaxial La2CrFeO6 double-perovskite films grown by pulsed-laser\ndeposition under various conditions. The highest ordered sample exhibited a\nfraction of antisite-disorder of only 0.05 and a saturation magnetization of\n~2\\mu_{B} per formula unit at 5 K. The result is consistent with the\nantiferromagnetic ordering of local spin moment\n(3d^{3}_{\\downarrow}3d^{5}_{\\uparrow}; S = -3/2+5/2 = 1). Therefore, the\nmagnetic ground state of La2CrFeO6 double-perovskite that has been long debate\nis unambiguously revealed to be ferrimagnetic. Our results present a wide\nopportunity to explore novel magnetic properties of binary transition-metal\nperovskites upon epitaxial stabilization of the ordered phase.",
        "positive": "Evaluation of Phosphorene as Anode Material for Na-ion Batteries from\n  First Principles: We systematically evaluate the prospects of a novel 2D nanomaterial,\nphosphorene, as anode for Na-ion batteries. Using first-principles\ncalculations, we determine the Na adsorption energy, specific capacity and Na\ndiffusion barriers on monolayer phosphorene. We examine the main trends in\nelectronic structure and mechanical properties as a function of Na\nconcentration. We find favorable Na-phosphorene interaction with theoretical\ncapacity, exceeding those of alternative monolayer anodes for Na-ion batteries.\nWe find that Na-phosphorene undergoes semiconductor-metal transition at high Na\nconcentration. Our results show that Na diffusion on phosphorene is fast and\nanisotropic with the energy barrier of only 0.04 eV. Owing to the high\ncapacity, good stability, excellent electrical conductivity and high Na\nmobility, monolayer phosphorene is a very promising anode material for Na-ion\nbatteries. The calculated performance in terms of specific capacity and\ndiffusion barrier is compared to other layered 2D electrode materials, such as\ngraphene, MoS2, polysilane, etc."
    },
    {
        "anchor": "Fine tuning epitaxial strain in ferroelectrics: PbxSr(1-x)TiO3 on DyScO3: Epitaxial strain can be used to modify the properties of ferroelectric thin\nfilms. From the experimental viewpoint, the challenge is to fine-tune the\nmagnitude of the strain. We illustrate how, by using a suitable combination of\ncomposition and substrate, the magnitude of the epitaxial strain can be\ncontrolled in a continuous manner. The phase diagram of PbxSr1-xTiO3 films\ngrown epitaxially on (110)-DyScO3 is calculated using a Devonshire-Landau\napproach. A boundary between in-plane and out-of-plane oriented ferroelectric\nphases is predicted to take place at $x \\approx$ 0.8. A series of PbxSr1-xTiO3\nfilms grown by MBE show good agreement with the proposed phase diagram",
        "positive": "Role of Polar Phonons in the Photo Excited State of Metal Halide\n  Perovskites: The development of high efficiency perovskite solar cells has sparked a\nmultitude of measurements on the optical properties of these materials. For the\nmost studied methylammonium(MA)PbI$_3$ perovskite, a large range (6-55 meV) of\nexciton binding energies has been reported by various experiments. The\nexistence of excitons at room temperature is unclear. For the MAPb$X_3$\nperovskites we report on relativistic $GW$-BSE calculations. This method is\ncapable to directly calculate excitonic properties from first-principles. At\nlow temperatures it predicts exciton binding energies in agreement with the\nreported 'large' values. For MAPbI$_3$, phonon modes present in this frequency\nrange have a negligible contribution to the ionic screening. By calculating the\npolarisation in time from finite temperature molecular dynamics, we show that\nat room temperature this does not change. We therefore exclude ionic screening\nas an explanation for the experimentally observed reduction of the exciton\nbinding energy at room temperature."
    },
    {
        "anchor": "Indium Tin Oxide film characterization using the classical Hall effect: We have used the classical Hall effect to electrically characterize Indium\nTin Oxide (ITO) films grown by two different techniques on silica substrates.\nITO films have the unique property that they can be both electrically\nconducting (and to be used for a gate electrode for example) as well as\noptically transparent (at least in the visible part of the spectrum). In the\nnear infrared (NIR) the transmission typically reduces. However, the light\nabsorption can in principle be compensated by growing thinner films.",
        "positive": "Using atom probe tomography to understand Schottky barrier height\n  pinning at the ZnO:Al / SiO2 / Si interface: We use electronic transport and atom probe tomography to study ZnO:Al / SiO2\n/ Si Schottky junctions on lightly-doped n- and p-type Si. We vary the carrier\nconcentration in the the ZnO:Al films by two orders of magnitude but the\nSchottky barrier height remains constant, consistent with Fermi level pinning\nseen in metal / Si junctions. Atom probe tomography shows that Al segregates to\nthe interface, so that the ZnO:Al at the junction is likely to be metallic even\nwhen the bulk of the ZnO:Al film is semiconducting. We hypothesize that Fermi\nlevel pinning is connected to the insulator-metal transition in doped ZnO, and\nthat controlling this transition may be key to un-pinning the Fermi level in\noxide / Si Schottky junctions."
    },
    {
        "anchor": "Combining Machine Learning and Many-Body Calculations:\n  Coverage-Dependent Adsorption of CO on Rh(111): Adsorption of carbon monoxide (CO) on transition-metal surfaces is a\nprototypical process in surface sciences and catalysis. Despite its simplicity,\nit has posed great challenges to theoretical modeling. Pretty much all existing\ndensity functionals fail to accurately describe surface energies, CO adsorption\nsite preference, as well as adsorption energies simultaneously. Although the\nrandom phase approximation (RPA) cures these density functional theory\nfailures, its large computational cost makes it prohibitive to study the CO\nadsorption for any but the simplest ordered cases. Here, we address these\nchallenges by developing a machine-learned force field (MLFF) with near RPA\naccuracy for the prediction of coverage-dependent adsorption of CO on the\nRh(111) surface through an efficient on-the-fly active learning procedure and a\n$\\Delta$-machine learning approach. We show that the RPA-derived MLFF is\ncapable to accurately predict the Rh(111) surface energy, CO adsorption site\npreference as well as adsorption energies at different coverages that are all\nin good agreement with experiments. Moreover, the coverage-dependent\nground-state adsorption patterns and adsorption saturation coverage are\nidentified.",
        "positive": "Influence of tetragonal platelets on the dielectric permittivity of\n  0.964Na$_{1/2}$Bi$_{1/2}$TiO$_3$-0.036BaTiO$_3$: We study the temperature-dependent evolution of the octahedral tilt order in\na lead-free relaxor ferroelectric and its impact on the ferroelectric\nproperties. Using diffuse neutron scattering on a\n0.964Na$_{1/2}$Bi$_{1/2}$TiO$_3$-0.036BaTiO$_3$ single crystal, we suggest a\nmodel for the temperature-dependent nanostructure of this perovskite that\nfeatures chemically pinned tetragonal platelets embedded in the rhombohedral\nmatrix, often separated by a cubic intermediate phase. Our results show a clear\ncorrelation between the squared thickness of the tetragonal platelets and the\ndielectric permittivity. This is interpreted as a sign for increased\npolarizability of the strained and distorted lattice at the center of the\ntetragonal platelets."
    },
    {
        "anchor": "Defect stability in phase-field crystal models: Stacking faults and\n  partial dislocations: The primary factors controlling defect stability in phase-field crystal (PFC)\nmodels are examined, with illustrative examples involving several existing\nvariations of the model. Guidelines are presented for constructing models with\nstable defect structures that maintain high numerical efficiency. The general\nframework combines both long-range elastic fields and basic features of\natomic-level core structures, with defect dynamics operable over diffusive time\nscales. Fundamental elements of the resulting defect physics are characterized\nfor the case of fcc crystals. Stacking faults and split Shockley partial\ndislocations are stabilized for the first time within the PFC formalism, and\nvarious properties of associated defect structures are characterized. These\ninclude the dissociation width of perfect edge and screw dislocations, the\neffect of applied stresses on dissociation, Peierls strains for glide, and\ndynamic contraction of gliding pairs of partials. Our results in general are\nshown to compare favorably with continuum elastic theories and experimental\nfindings.",
        "positive": "Continous Temkin theory of interface: We present differential equation for evolution of interface based on\ncontinuous approximation of Temkin's model"
    },
    {
        "anchor": "Anomalous Nuclear Quantum Effects in Ice: One striking anomaly of water ice has been largely neglected and never\nexplained. Replacing hydrogen ($^1$H) by deuterium ($^2$H) causes ice to\nexpand, whereas the \"normal\" isotope effect is volume contraction with\nincreased mass. Furthermore, the anomaly increases with temperature $T$, even\nthough a normal isotope shift should decrease with $T$ and vanish when $T$ is\nhigh enough to use classical nuclear motions. In this study, we show that these\neffects are very well described by {\\it ab initio} density functional theory.\nOur theoretical modeling explains these anomalies, and allows us to predict and\nto experimentally confirm a counter effect, namely that replacement of $^{16}$O\nby $^{18}$O causes a normal lattice contraction.",
        "positive": "Analytical model for the intensity dependence of 1500 nm to 980 nm\n  upconversion in Er$^{3+}$: a new tool for material characterization: We propose a simplified rate-equation model for the 1500 nm to 980 nm\nupconversion in Er$^{3+}$. The simplifications, based on typical experimental\nconditions as well as on conclusions based on previously published more\nadvanced models, enable an analytical solution of the rate equations, which\nreproduces known properties of upconversion. We have compared the model\npredictions with intensity-dependent measurements on four samples with\ndifferent optical properties, such as upconversion-luminescence yield and the\ncharacteristic lifetime of the $^4I_{13/2}$ state. The saturation of the\nupconversion is in all cases well-described by the model over several orders of\nmagnitude in excitation intensities. Finally, the model provides a new measure\nfor the quality of upconverter systems based on Er$^{3+}$ -- the saturation\nintensity. This parameter provides valuable information on upconversion\nparameters such as the rates of energy-transfer upconversion and\ncross-relaxation. In the present investigation, we used the saturation\nintensity to conclude that the differences in upconversion performance of the\ninvestigated samples are mainly due to differences in the non-radiative\nrelaxation rates."
    },
    {
        "anchor": "Amorphous-like Density of Gap States in Single Crystal Pentacene: We show that optical and electrical measurements on pentacene single crystals\ncan be used to extract the density of states in the HOMO-LUMO bandgap. It is\nfound that these highly purified crystals possess band tails broader than those\ntypically observed in inorganic amorphous solids. Results on field effect\ntransistors (FETs) fabricated from similar crystals are also compared. The FET\ndata imply that the gap state density is much larger within 5-10 nm of the gate\ndielectric. These results are discussed in terms of both crystal phase domains\nand structural disorder mechanisms.",
        "positive": "Band Offsets at the Si/SiO$_2$ Interface from Many-Body Perturbation\n  Theory: We use many-body perturbation theory, the state-of-the-art method for band\ngap calculations, to compute the band offsets at the Si/SiO$_2$ interface. We\nexamine the adequacy of the usual approximations in this context. We show that\n(i) the separate treatment of band-structure and potential lineup\ncontributions, the latter being evaluated within density-functional theory, is\njustified, (ii) most plasmon-pole models lead to inaccuracies in the absolute\nquasiparticle corrections, (iii) vertex corrections can be neglected, (iv)\neigenenergy self-consistency is adequate. Our theoretical offsets agree with\nthe experimental ones within 0.3 eV."
    },
    {
        "anchor": "Short-range order in high entropy alloys:Theoretical formulation and\n  application to Mo-Nb-Ta-V-W system: In high-entropy alloys (HEAs), the local chemical fluctuations from\ndisordered solute solution state into segregation, precipitation and ordering\nconfigurations are complex due to the large number of elements. In this work,\nthe cluster expansion (CE) Hamiltonian for multi-component alloy systems is\ndeveloped in order to investigate the dependence of chemical ordering of HEAs\nas a function of temperature dependence due to derivation of configuration\nentropy from the ideal solute solution. Analytic expressions for Warren-Cowley\nshort-range order (SRO) parameters are derived for a five component alloy\nsystem. The theoretical formulation is used to investigate the evolution of the\nten different SRO parameters in the MoNbTaVW and the sub-quaternary systems\nobtained by MonteCarlo simulations within the combined CE and first-principles\nformalism.",
        "positive": "Quantum Monte Carlo calculations of structural properties of FeO under\n  pressure: We determine the equation of state of stoichiometric FeO employing the\ndiffusion Monte Carlo method. The fermionic nodes are fixed to those of a wave\nfunction having the form of a single Slater determinant. The calculated ambient\npressure properties (lattice constant, bulk modulus and cohesive energy) agree\nvery well with available experimental data. At approximately 65 GPa, the\nlattice structure is found to change from rocksalt type (B1) to NiAs based\n(inverse B8)."
    },
    {
        "anchor": "Correlated Electron Pseudopotentials for 3d-Transition Metals: A recently published correlated electron pseudopotentials (CEPPs) method has\nbeen adapted for application to the 3d-transition metals, and to include\nrelativistic effects. New CEPPs are reported for the atoms Sc$-$Fe, constructed\nfrom atomic quantum chemical calculations that include an accurate description\nof correlated electrons. Dissociation energies, molecular geometries, and\nzero-point vibrational energies of small molecules are compared with all\nelectron results, with all quantities evaluated using coupled cluster singles\ndoubles and triples (CCSD(T)) calculations. The CEPPs give better results in\nthe correlated-electron calculations than Hartree-Fock-based pseudopotentials\navailable in the literature.",
        "positive": "Band dispersion of graphene with structural defects: We study the band dispersion of graphene with randomly distributed structural\ndefects using two complementary methods, exact diagonalization of the\ntight-binding Hamiltonian and implementing a self-consistent T matrix\napproximation. We identify three distinct types of impurities resulting in\nqualitatively different spectra in the vicinity of the Dirac point. First,\nresonant impurities, such as vacancies or 585 defects, lead to stretching of\nthe spectrum at the Dirac point with a finite density of localized states. This\ntype of spectrum has been observed in epitaxial graphene by photoemission\nspectroscopy and discussed extensively in the literature. Second, nonresonant\n(weak) impurities, such as paired vacancies or Stone-Wales defects, do not\nstretch the spectrum but provide a line broadening that increases with energy.\nFinally, disorder that breaks sublattice symmetry, such as vacancies placed in\nonly one sublattice, open a gap around the Dirac point and create an impurity\nband in the middle of this gap. We find good agreement between the results of\nthe two methods and also with the experimentally measured spectra."
    },
    {
        "anchor": "The Microscopic Diamond Anvil Cell: Stabilization of Superhard,\n  Superconducting Carbon Allotropes at Ambient Pressure: A metallic covalently bonded carbon allotrope is predicted via first\nprinciples calculations. It is composed of an $sp^3$ carbon framework that acts\nas a diamond anvil cell by constraining the distance between parallel\ncis-polyacetylene chains. The distance between these $sp^2$ carbon atoms\nrenders the phase metallic, and yields two well-nested nearly parallel bands\nthat span the Fermi level. Calculations show that this phase is a conventional\nsuperconductor, with the motions of the $sp^2$ carbons being key contributors\nto the electron phonon coupling. The $sp^3$ carbon atoms impart superior\nmechanical properties, with a predicted Vickers hardness of 48~GPa. This phase,\nmetastable at ambient conditions, could be made via cold compression of\ngraphite to 40~GPa. A family of multifunctional materials with tunable\nsuperconducting and mechanical properties could be derived from this phase by\nvarying the $sp^2$ versus $sp^3$ carbon content and by doping.",
        "positive": "Magnetic Effects on Dielectric and Polarization Behavior of Multiferroic\n  Hetrostructures: PbZr0.52Ti0.48O3/La0.67Sr0.33MnO3(PZT/LSMO) bilayer with surface roughness ~\n1.8 nm thin films have been grown by pulsed laser deposition on LaAlO3(LAO)\nsubstrates. High remnant polarization (30-54 micro C/cm2), dielectric\nconstant(400-1700), and well saturated magnetization were observed depending\nupon the deposition temperature of the ferromagnetic layer and applied\nfrequencies. Giant frequency-dependent change in dielectric constant and loss\nwere observed above the ferromagnetic-paramagnetic temperature. The frequency\ndependent dielectric anomalies are attributed to the change in metallic and\nmagnetic nature of LSMO and also the interfacial effect across the bilayer; an\nenhanced magnetoelectric interaction may be due to the Parish-Littlewood\nmechanism of inhomogeneity near the metal-dielectric interface."
    },
    {
        "anchor": "Magnetic Amplification at Yb3+ \"Designer Defects\" in the van der Waals\n  Ferromagnet, CrI3: The two-dimensional (2D) van der Waals ferromagnet CrI3 has been doped with\nthe magnetic optical impurity Yb3+ to yield materials that display sharp\nmulti-line Yb3+ photoluminescence (PL) controlled by the magnetism of CrI3.\nMagneto-PL shows that Yb3+ magnetization is pinned to the magnetization of\nCrI3. An effective internal field of ~10 T at Yb3+ is estimated, attributed to\nstrong in-plane Yb3+-Cr3+ superexchange coupling. The anomalously low energy of\nYb3+ PL in CrI3 reflects relatively high Yb3+-I- covalency, contributing to\nYb3+-Cr3+ superexchange coupling. The Yb3+ PL energy and linewidth both reveal\nthe effects of spontaneous zero-field CrI3 magnetic ordering within 2D layers\nbelow TC, despite the absence of net magnetization in multilayer samples. These\nresults illustrate the use of optical impurities as \"designer defects\" to\nintroduce unique functionality to 2D magnets.",
        "positive": "Ab initio tight binding for large-scale electronic-structure\n  calculations of semiconductors at finite temperatures: Calculating the electronic structure of materials at finite temperatures is\nimportant for rationalizing their physical properties and assessing their\ntechnological capabilities. However, finite-temperature calculations typically\nrequire large system sizes or long simulation times. This is challenging for\nnon-empirical theoretical methods because the involved bottleneck of performing\nmany first-principles calculations can pose a steep computational barrier for\nlarger systems. While machine-learning molecular dynamics enables\nlarge-scale/long-time simulations of the structural properties, the difficulty\nof computing in particular the electronic structure of large and disordered\nmaterials still remains. In this work, we suggest an adaptation of the\ntight-binding formalism which allows for computationally efficient calculations\nof temperature-dependent properties of semiconductors from existing\nmolecular-dynamics trajectories without explicitly fitting\ntemperature-dependent data. Our ab initio tight-binding approach utilizes\nhybrid-orbital basis functions and a modeling of the distance dependence of\nmatrix elements via numerical integration of atomic orbitals. We show that\nthese design choices lead to a tight-binding model with a minimal amount of\nparameters which are straightforwardly optimized using density functional\ntheory or alternative electronic-structure methods. Combining tight binding\nwith machine-learning molecular dynamics and hybrid density functional theory,\nwe find that it accurately describes finite-temperature electronic properties\nin comparison to experiment for the prototypical semiconductor gallium\narsenide."
    },
    {
        "anchor": "High three dimensional thermoelectric performance from low dimensional\n  bands: Reduced dimensionality has long been regarded as an important strategy for\nincreasing thermoelectric performance, for example in superlattices and other\nengineered structures. Here we point out and illustrate by examples that three\ndimensional bulk materials can be made to behave as if they were two\ndimensional from the point of view of thermoelectric performance. Implications\nfor the discovery of new practical thermoelectrics are discussed.",
        "positive": "Molecular Self-Assembly of Jointed Molecules on a Metallic Substrate:\n  From Single Molecule to Monolayer: Because of its promising contribution to the bottom-up approach for\nnanofabrication of complex molecular architectures, self-organization is widely\nstudied nowadays. Numerous studies have tackled supramolecular chirality or\nlow-dimensional molecular nanostructures using in most cases small and rigid\nmolecules adsorbed on metallic substrates. In this situation, self-assembled\nstructures can be understood in relative simple terms considering\nmolecule-molecule versus molecule-substrate interactions. In contrast, the case\nof large and three-dimensional molecules which can adopt different adsorption\nconformations is more complex. Here, we investigate the self-assembly of\nV-Landers molecules (C108H104) on Cu(100) by STM at room temperature under\nultrahigh vacuum. This molecule is constituted of a central poly-aromatic board\nlinked by sigma bonds to four 3,5-di-tert-butylphenyl legs."
    },
    {
        "anchor": "Importance of surface oxygen vacancies for ultrafast hot carrier\n  relaxation and transport in Cu$_2$O: Cu$_2$O has appealing properties as an electrode for photo-electrochemical\nwater splitting, yet its practical performance is severely limited by\ninefficient charge extraction at the interface. Using hybrid DFT calculations,\nwe investigate carrier capture processes by oxygen vacancies (V$_\\mathrm{O}$)\nin the experimentally observed ($\\sqrt{3} \\times \\sqrt{3}$)R30$^{\\circ}$\nreconstruction of the dominant (111) surface. Our results show that these\nV$_\\mathrm{O}$ are doubly ionized and that associated defects states strongly\nsuppress electron transport. In particular, the excited electronic state of a\nsingly charged V$_\\mathrm{O}$ plays a crucial role in the non-radiative\nelectron capture process with a capture coefficient of about 10$^{-9}$~cm$^3$/s\nand a lifetime of 0.04~ps, explaining the experimentally observed ultrafast\ncarrier relaxation. These results highlight that engineering the surface\nV$_\\mathrm{O}$ chemistry will be a crucial step in optimizing Cu$_2$O for\nphotoelectrode applications.",
        "positive": "Strain Effects on Auger-Meitner Recombination in Silicon: We study the effects of compressive and tensile biaxial strain on direct and\nphonon-assisted Auger-Meitner recombination (AMR) in silicon using\nfirst-principles calculations. We find that the application of strain has a\nnon-trivial effect on the AMR rate. For most AMR processes, the application of\nstrain increases the AMR rate. However, the recombination rate for the AMR\nprocess involving two holes and one electron is suppressed by 38% under tensile\nstrain. We further analyze the specific phonon contributions that mediate the\nphonon-assisted AMR mechanism, demonstrating the increased anisotropy under\nstrain. Our results indicate that the application of tensile strain increases\nthe lifetime of minority electron carriers in p-type silicon, and can be\nleveraged to improve the efficiency of silicon devices."
    },
    {
        "anchor": "On-surface synthesis and evolution of self-assembled poly($p$-phenylene)\n  chains on Ag(111): a joint experimental and theoretical study: The growth of controlled 1D carbon-based nanostructures on metal surfaces is\na multistep process whose path, activation energies and intermediate metastable\nstates strongly depend on the employed substrate. Whereas this process has been\nextensively studied on gold, less work has been dedicated to silver surfaces,\nwhich have a rather different catalytic activity. In this work, we present an\nexperimental and theoretical investigation of the growth of poly-$p$-phenylene\n(PPP) chains and subsequent narrow graphene ribbons starting from\n4,4''-dibromo-$p$-terphenyl molecular precursors deposited at the silver\nsurface. By combing scanning tunneling microscopy (STM) imaging and density\nfunctional theory (DFT) simulations, we describe the molecular morphology and\norganization at different steps of the growth process and we discuss the\nstability and conversion of the encountered species on the basis of calculated\nthermodynamic quantities. Unlike the case of gold, at the debromination step we\nobserve the appearance of organometallic molecules and chains, which can be\nexplained by their negative formation energy in the presence of a silver adatom\nreservoir. At the dehydrogenation temperature the persistence of intercalated\nBr atoms hinders the formation of well-structured graphene ribbons, which are\ninstead observed on gold, leading only to a partial lateral coupling of the PPP\nchains. We numerically derive very different activation energies for Br\ndesorption from the Ag and Au surfaces, thereby confirming the importance of\nthis process in defining the kinetics of the formation of molecular chains and\ngraphene ribbons on different metal surfaces.",
        "positive": "Electron emission from conduction band of diamond with negative electron\n  affinity: Experimental evidence explaining the extremely low-threshold electron\nemission from diamond reported in 1996 has been obtained for the first time.\nDirect observation using combined ultraviolet photoelectron spectroscopy/field\nemission spectroscopy (UPS/FES) proved that the origin of field-induced\nelectron emission from heavily nitrogen (N)-doped chemical vapour deposited\n(CVD) diamond was at conduction band minimum (CBM) utilising negative electron\naffinity (NEA). The significance of the result is that not only does it prove\nthe utilisation of NEA as the dominant factor for the extremely low-threshold\nelectron emission from heavily N-doped CVD diamond, but also strongly implies\nthat such low-threshold emission is possible from other types of diamond, and\neven other materials having NEA surface. The low-threshold voltage, along with\nthe stable intensity and remarkably narrow energy width, suggests that this\ntype of electron emission can be applied to develop a next generation vacuum\nnano-electronic devices with long lifetime and high energy resolution."
    },
    {
        "anchor": "Ab initio molecular dynamics calculations of threshold displacement\n  energies in silicon carbide: Using first principles molecular dynamics simulations, we have determined the\nthreshold displacement energies and the associated created defects in cubic\nsilicon carbide. Contrary to previous studies using classical molecular\ndynamics, we found values close to the experimental consensus, and also created\ndefects in good agreement with recent works on interstitials stability in\nsilicon carbide. We carefully investigated the limits of this approach. Our\nwork shows that it is possible to calculate displacement energies with first\nprinciples accuracy in silicon carbide, and suggests that it may be also the\ncase for other covalent materials.",
        "positive": "Mixed Formamidinium-Methylammonium Lead Iodide perovskite from\n  first-principles: Hydrogen-bonding impact on the electronic properties: Hybrid perovskites with mixed organic cations such as methylammonium and\nformamidinium have attracted interest due to their improved stability and\ncapability to tune their properties varying the composition. In this work we\nreport on the local variation of the structural and electronic properties in\nmixed A-site cation MA/FA lead iodide perovskites FAXMA1-XPBI3 evaluated from\nstatic first-principles calculations in certain structures where the\norientations of organic cations result from examining the energy landscape of\nsome compositions. The cation replacement at the A-site to form the solid\nsolution causes an increase tilting of the inorganic PbI6 octahedra: in the\nFA-rich compounds the replacement of FA by a smaller cation like MA is to\ncompensate the reduced space filling offered by the smaller cation, whereas in\nthe MA-rich compounds is to expand the space needed for the larger cation. In\nfact, the effect of octahedron tiltings exceeds that of unit-cell size in\ndetermining the band gap for these organic cation mixtures. Our calculations\nindicate that the key role played by hydrogen bonds with iodine anions in pure\ncompounds is preserved in the cation mixed perovskites. It is found that MA-I\nbonds remain stronger than FA-I bonds throughout the composition range\nregardless of the unit-cell expansion as the FA content increases. Our\ncalculations reveal how the hydrogen bonds stabilize the no-bonding I-5p\norbitals, spatially perpendicular to the Pb-I-Pb bond axis, lowering their\nenergy when the H-I interaction occurs, which would explain the well-known role\nof hydrogen bonding in the structural stabilization of hybrid perovskites.\nThese results contribute to the understanding on the role played by cation\nmixing at A sites in the physics of lead halide perovskites."
    },
    {
        "anchor": "Tight-binding approach to understand photoelectron intensity from\n  graphene for circularly polarized light: We have investigated the effect of imperfect circular polarization on the\nangle-resolved photoemission spectroscopy signal, using graphene as a\nprototypical system that can be understood within tight-binding formalism. We\nfound that perfect left- and right-circularly polarized lights give the same\nphotoelectron intensity distribution around a constant energy contour of the\ngraphene $\\pi$ band. On the other hand, upon breaking the purity of the\npolarization, photoelectron intensity starts to show circular dichroism, which\nis enhanced with further increasing the imperfection. Our results predict the\nexistence of an additional factor for the circular dichroism observed in the\nphotoemission signal from graphene and hence suggest the importance of\nexperimental conditions to understand circular dichroism observed via\nphotoemission spectroscopy.",
        "positive": "Layered, Tunable Graphene Oxide-Nylon Heterostructures for Wearable\n  Electrocardiogram Sensors: Nanoscale engineered materials combined with wearable wireless technologies\ncan deliver a new level of health monitoring. A reduced graphene oxide-nylon\ncomposite material is developed and tested, demonstrating its usefulness as a\nmaterial for sensors in wearable, long-term electrocardiogram (ECG) monitoring\nvia a comparison to one of the widely used ECG sensors. The structural analysis\nby scanning electron (SEM) and atomic force microscopy (AFM) shows a limited\nnumber of defects on a macroscopic scale. Fourier Transform Infrared (FTIR) and\nRaman spectroscopy confirm the presence of rGOx, and the ratio of D- and\nG-features as a function of thickness correlates with the resistivity analysis.\nThe negligible effect of the defects and the tunability of electrical and\noptical properties, together with live ECG data, demonstrate its signal\ntransduction capability."
    },
    {
        "anchor": "Linear laws of volume elasticity in the properties and structural phase\n  transitions: physical process of the parameter effect (TPH) in\n  magnet-structures: The present paper deals with the analysis of experimental results taking into\naccount mechanisms brought by the bulk elastic energy transformed by the\nthermodynamic parameters, temperature, magnetic fields, high hydrostatic\npressure (T-H-P). An effect of the external parameters is considered through\nthe separation of critical lines and points of the cooling-heating effect in\nthe course of analysis of linear elastic evolution of properties in sign\nalternating and crossing effects of elastic stress energy as well as their\nvalue for structural reorganizations at reversible volume changes (structural\nphase transformations of types I and II). An explanation of the direct and\nreverse hysteresis effect in the range of the structural phase transitions I\nand II is suggested and the secondary signs of changes of phase state\nproperties in the wide range of structures are formulated. The regularities of\nformation of a structural phase transition at 0 K are stated with separating\nthe position of the triple point and the change of the properties and phase\nstates with the elements of superconducting and conducting properties.",
        "positive": "Adsorbed 3d transition metal atoms and clusters on Au(111):Signatures\n  derived from one electron calculations: The spectroscopic characteristics of systems with adsorbed d impurities on\nnoble metal surfaces should depend on the number and geometric arrangement of\nthe adsorbed atoms and also on their d band filling. Recent experiments using\nscanning tunneling microscopy have probed the electronic structure of all 3d\ntransition metal impurities and also of Co dimers adsorbed on Au(111),\nproviding a rich variety of results. In this contribution we correlate those\nexperimental results with ab-initio calculations and try to establish necessary\nconditions for observing a Kondo resonance when using the single impurity\nAnderson model. We find that the relevant orbitals at the STM tip position,\nwhen it is on top of an impurity, are the dThe spectroscopic characteristics of\nsystems with adsorbed d impurities on noble metal surfaces should depend on the\nnumber and geometric arrangement of the adsorbed atoms and also on their d band\nfilling. Recent experiments using scanning tunneling microscopy have probed the\nelectronic structure of all 3d transition metal impurities and also of Co\ndimers adsorbed on Au(111), providing a rich variety of results. In this\ncontribution we correlate those experimental results with ab-initio\ncalculations and try to establish necessary conditions for observing a Kondo\nresonance when using the single impurity Anderson model. We find that the\nrelevant orbitals at the STM tip position, when it is on top of an impurity,\nare the d orbitals with m=0 and that the energy of these levels with respect to\nthe Fermi energy determines the possibility of observing a spectroscopic\nfeature due to the impurity. orbitals with m=0 and that the energy of these\nlevels with respect to the Fermi energy determines the possibility of observing\na spectroscopic feature due to the impurity."
    },
    {
        "anchor": "Observation of non-trivial topological electronic structure of\n  orthorhombic SnSe: Topological electronic structures are key to the topological classification\nof quantum materials and play an important role in their physical properties\nand applications. Recently, SnSe has attracted great research interests due to\nits superior thermoelectric performance. However, it's topological nature has\nlong been ignored. In this work, by combining synchrotron-based angle-resolved\nphotoemission spectroscopy and ab-initio calculations, we systematically\ninvestigated the topological electronic structure of orthorhombic SnSe. By\nidentifying the continuous gap in the valence bands due to the band inversion\nand the topological surface states on its (001) surface, we establish SnSe as a\nstrong topological insulator. Furthermore, we studied the evolution of the\ntopological electronic structure and propose the topological phase diagram in\nSnSe1-xTex. Our work reveals the topological non-trivial nature of SnSe and\nprovides new understandings of its intriguing transport properties.",
        "positive": "Magnons and Magnetodielectric Effects in CoCr$_2$O$_4$: Raman Scattering\n  Studies: Magnetoelectric materials have generated wide technological and scientific\ninterest because of the rich phenomena these materials exhibit, including the\ncoexistence of magnetic and ferroelectric orders, magnetodielectric behavior,\nand exotic hybrid excitations such as electromagnons. The multiferroic spinel\nmaterial, CoCr$_2$O$_4$, is a particularly interesting example of a\nmultiferroic material, because evidence for magnetoelectric behavior in the\nferrimagnetic phase seems to conflict with traditional noncollinear-spin-driven\nmechanisms for inducing a macroscopic polarization. This paper reports an\ninelastic light scattering study of the magnon and phonon spectrum of\nCoCr$_2$O$_4$ as simultaneous functions of temperature, pressure, and magnetic\nfield. Below the Curie temperature ($T_C \\sim 94$ K) of CoCr$_2$O$_4$ we\nobserve a $\\omega \\sim 16 \\,\\text{cm}^{-1}$ $\\boldsymbol q=0$ magnon having\nT$_{1g}$-symmetry, which has the transformation properties of an axial vector.\nThe anomalously large Raman intensity of the T$_{1g}$-symmetry magnon is\ncharacteristic of materials with a large magneto-optical response and likely\narises from large magnetic fluctuations that strongly modulate the dielectric\nresponse in CoCr$_2$O$_4$. The Raman susceptibility of the T$_{1g}$-symmetry\nmagnon exhibits a strong magnetic-field dependence that is consistent with the\nmagnetodielectric response observed in CoCr$_2$O$_4$, suggesting that\nmagnetodielectric behavior in CoCr$_2$O$_4$ primarily arises from the\nfield-dependent suppression of magnetic fluctuations that are strongly coupled\nto long-wavelength phonons. Increasing the magnetic anisotropy in CoCr$_2$O$_4$\nwith applied pressure decreases the magnetic field-dependence of the\nT$_{1g}$-symmetry magnon Raman susceptibility in CoCr$_2$O$_4$, suggesting that\nstrain can be used to control the magnetodielectric response in CoCr$_2$O$_4$."
    },
    {
        "anchor": "Magnetic domain and magnetic resistance phase transition in strongly\n  correlated electronic material of perovskites junction: The junction magnetoresistivity and domain phase transition were studied\nbetween ZnO and La0.4Gd0.1Sr0.5CoO3 thin films grown on LaAlO3 (100) substrates\nepitaxially by pulse laser deposit. The ferromagnetic transformation into\nphase-separated (two phase) state was displayed below Tc~127 and has observed\nthat the lattice change discontinuously in the doped cobalt perovskites\nLa0.4Gd0.1Sr0.5CoO3. The Ginzburg-Landau phase field is introduced to deduce\nantiferroelectric domain structure in LGSCO thin film. On the basis of the\ndomain structures, the phase boundary of thin film is strongly dependent on the\ncombination of electric-mechanical coupling. The phase transformation into\nphase separated state occurs below Tc~127-128K, and have displayed that the\nlattice constants change discontinuously at the transformation. The positive MR\nof ZnO/LGSCO heterojunction exhibited the MIT behavior at 0.2 T is 4.86%, at\n0.5 T is 6.05% for approximately 140K.",
        "positive": "Determining key spin-orbitronic parameters by means of propagating spin\n  waves: We characterize spin wave propagation and its modification by an electrical\ncurrent in Permalloy(Py)/Pt bilayers with Py thickness between 4 and 20 nm.\nFirst, we analyze the frequency non-reciprocity of surface spin waves and\nextract from it the interfacial Dzyaloshinskii-Moriya interaction constant\n$D_s$ accounting for an additional contribution due to asymmetric surface\nanisotropies. Second, we measure the spin-wave relaxation rate and deduce from\nit the Py/Pt spin mixing conductance $g^{\\uparrow\\downarrow}_{eff}$. Last,\napplying a \\textit{dc} electrical current, we extract the spin Hall\nconductivity $\\sigma_{SH}$ from the change of spin wave relaxation rate due to\nthe spin-Hall spin transfer torque. We obtain a consistent picture of the spin\nwave propagation data for different film thicknesses using a single set of\nparameters $D_s=0.25$ pJ/m, $g^{\\uparrow\\downarrow}_{eff} = 3.2\\times 10^{19}$\nm$^{-2}$ and $\\sigma_{SH}=4\\times10^{5}$ S/m."
    },
    {
        "anchor": "Simulations of Time-Resolved X-Ray Diffraction in Laue Geometry: A method of computer simulation of Time-Resolved X-ray Diffraction (TRXD) in\nasymmetric Laue (transmission) geometry with an arbitrary propagating strain\nperpendicular to the crystal surface is presented. We present two case studies\nfor possible strain generation by short-pulse laser irradiation: (i) a\nthermoelastic-like analytic model; (ii) a numerical model including effects of\nelectron-hole diffusion, Auger recombination, deformation potential and thermal\ndiffusion. A comparison with recent experimental results is also presented.",
        "positive": "Electric Field-Tuned Topological Phase Transition in Ultra-Thin Na3Bi -\n  Towards a Topological Transistor: The electric field induced quantum phase transition from topological to\nconventional insulator has been proposed as the basis of a topological field\neffect transistor [1-4]. In this scheme an electric field can switch 'on' the\nballistic flow of charge and spin along dissipationless edges of the\ntwo-dimensional (2D) quantum spin Hall insulator [5-9], and when 'off' is a\nconventional insulator with no conductive channels. Such as topological\ntransistor is promising for low-energy logic circuits [4], which would\nnecessitate electric field-switched materials with conventional and topological\nbandgaps much greater than room temperature, significantly greater than\nproposed to date [6-8]. Topological Dirac semimetals(TDS) are promising systems\nin which to look for topological field-effect switching, as they lie at the\nboundary between conventional and topological phases [3,10-16]. Here we use\nscanning probe microscopy/spectroscopy (STM/STS) and angle-resolved\nphotoelectron spectroscopy (ARPES) to show that mono- and bilayer films of TDS\nNa3Bi [3,17] are 2D topological insulators with bulk bandgaps >400 meV in the\nabsence of electric field. Upon application of electric field by doping with\npotassium or by close approach of the STM tip, the bandgap can be completely\nclosed then re-opened with conventional gap greater than 100 meV. The large\nbandgaps in both the conventional and quantum spin Hall phases, much greater\nthan the thermal energy kT = 25 meV at room temperature, suggest that ultrathin\nNa3Bi is suitable for room temperature topological transistor operation."
    },
    {
        "anchor": "In Situ Epitaxy of Pure Phase Ultra-Thin InAs-Al Nanowires for Quantum\n  Devices: Hybrid semiconductor-superconductor InAs-Al nanowires with uniform and\ndefect-free crystal interfaces are one of the most promising candidates used in\nthe quest for Majorana zero modes (MZMs). However, InAs nanowires often exhibit\na high density of randomly distributed twin defects and stacking faults, which\nresult in an uncontrolled and non-uniform InAs-Al interface. Furthermore, this\ntype of disorder can create potential inhomogeneity in the wire, destroy the\ntopological gap, and form trivial sub-gap states mimicking MZM in transport\nexperiments. Further study shows that reducing the InAs nanowire diameter from\ngrowth can significantly suppress the formation of these defects and stacking\nfaults. Here, we demonstrate the in situ growth of ultra-thin InAs nanowires\nwith epitaxial Al film by molecular-beam epitaxy. Our InAs diameter (~ 30 nm)\nis only one-third of the diameters (~ 100 nm) commonly used in literatures. The\nultra-thin InAs nanowires are pure phase crystals for various different growth\ndirections, suggesting a low level of disorder. Transmission electron\nmicroscopy confirms an atomically sharp and uniform interface between the Al\nshell and the InAs wire. Quantum transport study on these devices resolves a\nhard induced superconducting gap and $2e^-$ periodic Coulomb blockade at zero\nmagnetic field, a necessary step for future MZM experiments. A large zero bias\nconductance peak with a peak height reaching 80% of $2e^2/h$ is observed.",
        "positive": "Insights into the structural symmetry of single-crystal YCrO$_3$ from\n  synchrotron X-ray diffraction: We report on the crystallographic information such as lattice parameters,\natomic positions, bond lengths and angles, and local crystalline distortion\nsize and mode of single-crystal YCrO$_3$ compound by a high-resolution\nsynchrotron X-ray diffraction study. The data was collected at 120 K (below\n$T_\\textrm{N} \\sim$ 141.5 K), 300 K (within [$T_\\textrm{N}$, $T_\\textrm{C}$]),\nand 500 K (above $T_\\textrm{C} \\sim$ 473 K). Taking advantages of high\nintensity and brilliance of synchrotron X-rays, we are able to refine collected\npatterns with the noncentrosymmetric monoclinic structural model ($P12_11$, No.\n4) that was proposed previously but detailed structural parameters have not\ndetermined yet. Meanwhile, we calculated patterns with the centrosymmetric\northorhombic space group (\\emph{Pmnb}, No. 62) for a controlled study. Lattice\nconstants \\emph{a}, \\emph{b}, and \\emph{c} as well as unit-cell volume almost\nincrease linearly upon warming. We observed more dispersive distributions of\nbond length and angle and local distortion strength with the $P12_11$ space\ngroup. This indicates that (i) The local distortion mode of Cr2O$_6$ at 120 K\ncorrelates the formation of the canted antiferromagnetic order by Cr1-Cr2 spin\ninteractions mainly through intermediate of O3 and O4 ions. (ii) The\nstrain-balanced Cr1-O3(O4) and Cr2-O5(O5) bonds as well as the local distortion\nmodes of Cr1O$_6$ and Cr2O$_6$ octohedra at 300 K may be a microscopic origin\nof the previously-reported dielectric anomaly. Our study demonstrates that\nlocal crystalline distortion is a key factor for the formation of ferroelectric\norder and provides a complete set of crystallography for a full understanding\nof the interesting magnetic and quasi-ferroelectric properties of YCrO$_3$\ncompound."
    },
    {
        "anchor": "Charge manipulation and imaging of the Mn acceptor state in GaAs by\n  Cross-sectional Scanning Tunneling Microscopy: An individual Mn acceptor in GaAs is mapped by Cross-sectional Scanning\nTunneling Microscopy (X-STM) at room temperature and a strongly anisotropic\nshape of the acceptor state is observed. An acceptor state manifests itself as\na cross-like feature which we attribute to a valence hole weakly bound to the\nMn ion forming the (Mn$^{2+}3d^5+hole$) complex. We propose that the observed\nanisotropy of the Mn acceptor wave-function is due to the d-wave present in the\nacceptor ground state.",
        "positive": "Accurate high-throughput screening of I-II-V 8-electron Half-Heusler\n  compounds for renewable-energy applications: Renewable energy resources have emerged as the best alternatives to fossil\nfuel energy which are rapidly declining with time. Here, eight valence-electron\ncount Half-Heusler(HH) alloys have been studied using reliable first principles\ncalculations in the search of potential candidates for renewable energy\napplications like thermoelectric (TE), solar harvesting, topological insulator\n(TI) and transparent conductor (TC) applications. The initial screening\nparameters used for our study are chemical and thermal stability, band gap,\nnature of bandgap and band inversion strength. We have performed quasistatic\nG0W0 calculation starting from HSE groundstate wavefunction to predict the most\naccurate estimation of bandgap for these class of compounds. A total of 960\ncompounds were simulated. 121 out of 960 compounds were found to be thermally\nand chemically stable. 31 compounds with bandgap less than 1.5 eV were studied\nfor thermoelectric application out of which 13 compounds were found to show\nthermoelectric figure of merit ZT > 0.7 for both p-type and n-type conduction.\n30 compounds with band gap 1-1.8 eV were studied for optoelectronic application\nout of which 13 compounds were found to show Spectroscopic Limited Maximum\nEfficiency (SLME) more than 20%, comparable to existing state of the art\nmaterials. 21 compounds were found to show band inversion at ambient conditions\nwhich is a necessary condition for topological insulators. The surface band\nstructure calculations for one of the promising candidate was done to check\nrobustness of the topological behaviour. 29 compounds were found to have\nbandgap more than 2 eV which are promoted for transparent conductor\napplications with further band engineering. We strongly believe that our\ncalculations will give useful insights to experimentalists for synthesizing and\ninvestigating proposed compounds for different energy applications."
    },
    {
        "anchor": "Topological insulators vs. topological Dirac semimetals in honeycomb\n  compounds: Intriguing physical property of materials stems from their chemical\nconstituent whereas the connection between them is often not clear. Here, we\nuncover a general chemical classification for the two quantum phases in the\nhoneycomb ABX structure--topological insulator (TI) and topological Dirac\nsemimetal (TDSM). First, we find among the 816 (existing as well as\nhypothetical) calculated compounds, 160 TI's (none were noted before), 96\nTDSM's, 282 normal insulators (NI's), and 278 metals. Second, based on this\nclassification, we have distilled a simple chemical regularity based on\ncompound formulae for the selectivity between TI and TDSM: The ABX compounds\nthat are TDSM have B atoms (part of the BX honeycomb layers) that come from the\nPeriodic Table columns XI (Cu, Ag, Au) or XII (Zn, Cd, Hg), or Mg (group II),\nwhereas the ABX compounds whose B atoms come from columns I (Li, Na, K, Rb, Cs)\nor II (Ca, Sr, Ba) are TI's. Third, focusing on the ABX Bismide compounds that\nare thermodynamically stable, we find a structural motif that delivers\ntopological insulation and stability at the same time. This study opens the way\nto simultaneously design new topological materials based on the compositional\nrules indicated here.",
        "positive": "Small Polaron Formation on the Nb-doped SrTiO$_\\textbf{3}$(001) Surface: The cubic perovsike strontium titanate SrTiO$_3$ (STO) is one of the most\nstudied, polarizable transition metal oxides. When excess charge is introduced\nto this material, e.g., through doping or atomic defects, STO tends to host\npolarons: Quasi-particles formed by excess charge carriers coupling with the\ncrystal phonon field. Their presence alters the materials properties, and is a\nkey for many applications. Considering that polarons form preferentially on or\nnear surfaces, we study small polaron formation at the TiO$_2$ termination of\nthe STO(001) surface via density functional theory calculations. We model\nseveral supercell slabs of Nb-doped and undoped STO(001) surfaces with\nincreasing size, also considering the recently observed as-cleaved TiO$_2$\nterminated surface hosting Sr-adatoms. Our findings suggest that small polarons\nbecome less stable at low concentrations of Nb-doping, in analogy with polarons\nlocalized in the bulk. Further, we inspect the stability of different polaron\nconfigurations with respect to Nb- and Sr-impurities, and discuss their\nspectroscopic properties."
    },
    {
        "anchor": "Sculptured Thin Films: Accomplishments and Emerging Uses: Sculptured thin films (STFs) are nano-engineered materials whose columnar\nmorphology is tailored to elicit desired optical responses upon excitation. Two\ncanonical forms of STFs have been identified. Linear constitutive relations for\ngeneral STFs as unidirectionally nonhomogeneous (continuously or piecewise\nuniformly) and locally bianisotropic continuums are presented, along with a\n4$\\times$4 matrix ordinary differential equation for wave propagation therein.\nA nominal model for the macroscopic properties of linear STFs is devised from\nnanoscopic considerations. The accomplished implementation of STFs as circular\npolarization filters and spectral hole filters is discussed, as also are\nemerging applications such as bioluminescence sensors and optical\ninterconnects.",
        "positive": "Thermal transport in van der Waals graphene/boron-nitride structure: a\n  molecular dynamics study: Among the van der Waals heterostructures, graphene/h-BN heterostructure is an\nappropriate candidate for 2D nanoelectronic devices. In this paper, using\nnon-equilibrium molecular dynamics simulation approach, heat transport in\nbilayer graphene/h-BN and graphene/h-BN van der Waals heterostructure (i.e.\nh-BN flakes periodically inserted on the top and bottom of a graphene layer)\nare explored. The results show that by increasing the length of the system, the\nthermal conductivity of bilayer graphene/h-BN increases. Furthermore, it was\nrevealed that heat transport in graphene/h-BN heterostructure enhances compared\nto that in monolayer graphene or monolayer h-BN. The size effect analysis shows\nthat the heat fluxes passing through each layer in bilayer graphene/h-BN\nconverges when the size of the system is larger than 100 nm. The results can\nimprove the understanding heat transfer phenomena in the van der Waals\nheterostructures and improve designing of heterostructures for better thermal\nmanagement and heat dissipation."
    },
    {
        "anchor": "Stability of subnanometer MoS wires under realistic environment: We carried out first-principles density functional theory calculations of\nhydrogen and oxygen adsorption and diffusion on subnanometer MoS nanowires. The\nnanowires are robust against adsorption of hydrogen. On the other hand,\ninteraction with oxygen shows that the nanowires can oxidize with a small\nbarrier. Our results open the path for understanding the behavior of MoS\nnanowires under realistic environment.",
        "positive": "X-ray diffraction peak profiles from threading dislocations in GaN\n  epitaxial films: We analyze the lineshape of x-ray diffraction profiles of GaN epitaxial\nlayers with large densities of randomly distributed threading dislocations. The\npeaks are Gaussian only in the central, most intense part of the peak, while\nthe tails obey a power law. The $q^{-3}$ decay typical for random dislocations\nis observed in double-crystal rocking curves. The entire profile is well fitted\nby a restricted random dislocation distribution. The densities of both edge and\nscrew threading dislocations and the ranges of dislocation correlations are\nobtained."
    },
    {
        "anchor": "Oxide spintronics: Concomitant with the development of metal-based spintronics in the late\n1980's and 1990's, important advances were made on the growth of high-quality\noxide thin films and heterostructures. While this was at first motivated by the\ndiscovery of high-temperature superconductivity in perovskite Cu oxides, this\ntechnological breakthrough was soon applied to other transition metal oxides,\nand notably mixed-valence manganites. The discovery of colossal\nmagnetoresistance in manganite films triggered an intense research activity on\nthese materials, but the first notable impact of magnetic oxides in the field\nof spintronics was the use of such manganites as electrodes in magnetic tunnel\njunctions, yielding tunnel magnetoresistance ratios one order of magnitude\nlarger than what had been obtained with transition metal electrodes. Since\nthen, the research on oxide spintronics has been intense with the latest\ndevelopments focused on diluted magnetic oxides and more recently on\nmultiferroics. In this paper, we will review the most important results on\noxide spintronics, emphasizing materials physics as well as spin-dependent\ntransport phenomena, and finally give some perspectives on how the flurry of\nnew magnetic oxides could be useful for next-generation spintronics devices.",
        "positive": "Nanoscale Investigation of Microcracks and Grain Boundary Wetting in\n  Press Hardened Galvanized 20MnB8 Steel: Grain boundary wetting as a preliminary stage for zinc induced grain boundary\nweakening and embrittlement in a Zn coated press hardened 20MnB8 steel was\nanalyzed by means of electron backscatter diffraction, Auger electron\nspectroscopy, energy dispersive X-ray analysis, atom probe tomography and\ntransmission electron microscopy on the nanometer scale. Microcracks at prior\naustenite grain boundaries were observed and structures that developed after\nmicrocrack formation were identified. Zn/Fe intermetallic phases with grain\nsizes smaller than 100 nm in diameter are present at the crack surfaces and at\nthe wedge-shaped crack tips. In order to get a complete picture, including the\nmicrostructure before cracking, an undeformed, electrolytically coated\nreference sample which underwent the same heat treatment as the press hardened\nmaterial was investigated. Here, Zn, in the order of one atomic layer or less,\ncould be found along prior austenite grain boundaries several micrometers away\nfrom the actual Zn/Fe phases in the coating. Such a grain boundary weakening by\nZn wetting of prior austenitic grain boundaries during austenitization and/or\nhot forming is a necessary condition for microcrack formation."
    },
    {
        "anchor": "Quantum embedding methods for correlated excited states of point\n  defects: Case studies and challenges: A quantitative description of the excited electronic states of point defects\nand impurities is crucial for understanding materials properties, and possible\napplications of defects in quantum technologies. This is a considerable\nchallenge for computational methods, since Kohn-Sham density-functional theory\n(DFT) is inherently a ground state theory, while higher-level methods are often\ntoo computationally expensive for defect systems. Recently, embedding\napproaches have been applied that treat defect states with many-body methods,\nwhile using DFT to describe the bulk host material. We implement such an\nembedding method, based on Wannierization of defect orbitals and the\nconstrained random-phase approximation approach, and perform systematic\ncharacterization of the method for three distinct systems with current\ntechnological relevance: a carbon dimer replacing a B and N pair in bulk\nhexagonal BN (C$_{\\text{B}}$C$_{\\text{N}}$), the negatively charged\nnitrogen-vacancy center in diamond (NV$^-$), and an Fe impurity on the Al site\nin wurtzite AlN ($\\text{Fe}_{\\text{Al}}$). For C$_{\\text{B}}$C$_{\\text{N}}$ we\nshow that the embedding approach gives many-body states in agreement with\nanalytical results on the Hubbard dimer model, which allows us to elucidate the\neffects of the DFT functional and double-counting correction. For the NV$^-$\ncenter, our method demonstrates good quantitative agreement with experiments\nfor the zero-phonon line of the triplet-triplet transition. Finally, we\nillustrate challenges associated with this method for determining the energies\nand orderings of the complex spin multiplets in $\\text{Fe}_{\\text{Al}}$.",
        "positive": "Competing mechanisms govern the thermal rectification behavior in\n  semi-stochastic polycrystalline graphene with graded grain-size distribution: Thermal rectifiers are devices that have different thermal conductivities in\nopposing directions of heat flow. The realization of practical thermal\nrectifiers relies significantly on a sound understanding of the underlying\nmechanisms of asymmetric heat transport, and two-dimensional materials offer a\npromising opportunity in this regard owing to their simplistic structures\ntogether with a vast possibility of tunable imperfections. However, the\nin-plane thermal rectification mechanisms in 2D materials like graphene having\ndirectional gradients of grain sizes have remained elusive. In fact,\nunderstanding the heat transport mechanisms in polycrystalline graphene, which\nare more practical to synthesize than large-scale single-crystal graphene,\ncould potentially allow a unique opportunity, in principle, to combine with\nother defects and designs for effective optimization of thermal rectification.\nIn this work, we investigate the thermal rectification behavior in periodic\natomistic models of polycrystalline graphene whose grain arrangements were\ngenerated semi-stochastically to have different gradient grain-density\ndistributions along the in-plane heat flow direction. We employ the centroidal\nVoronoi tessellation technique to generate realistic grain boundary structures\nfor graphene, and the non-equilibrium molecular dynamics simulations method is\nused to calculate the thermal conductivities and rectification values.\nAdditionally, detailed phonon characteristics and propagating phonon spatial\nenergy densities are analyzed based on the fluctuation-dissipation theory to\nelucidate the competitive interplay between two underlying mechanisms, namely,\n(1) propagating phonon coupling and (2) temperature-dependence of thermal\nconductivity that determine the degree of asymmetric heat flow in graded\npolycrystalline graphene."
    },
    {
        "anchor": "Emergence of directionally-anisotropic mobility in a faceted $\u03a3$11\n  <110> tilt grain boundary in Cu: Faceted grain boundaries, where grain boundary area is increased in the name\nof producing low-energy segments, can exhibit new and unexpected migration\ntrends. For example, several faceted $\\Sigma$3 boundaries have demonstrated\nanti-thermal and thermally damped mobility. $\\Sigma$11 <110> tilt boundaries\nrepresent another promising but relatively unexplored set of interfaces, with a\n(113) low-energy plane that can lead to faceting. In this study, molecular\ndynamics simulations are used to study grain boundary migration of an\nasymmetric $\\Sigma$11 <110> grain boundary in two face centered cubic metals.\nMobility of this boundary in Cu is strongly dependent on the direction of the\napplied driving force. The mobility anisotropy generally becomes smaller, but\ndoes not disappear completely, as temperature is increased. In contrast, the\nsame boundary in Al demonstrates similar mobilities in either direction,\nillustrating that the anisotropic mobility phenomenon is material-dependent.\nFinally, relationships between stacking fault energy, facet junction defect\ncontent, and boundary crystallography are uncovered that may inform future\nstudies of faceted grain boundaries.",
        "positive": "Dephasing of Transverse Spin Current in Ferrimagnetic Alloys: It has been predicted that transverse spin current can propagate coherently\n(without dephasing) over a long distance in antiferromagnetically ordered\nmetals. Here, we estimate the dephasing length of transverse spin current in\nferrimagnetic CoGd alloys by spin pumping measurements across the compensation\npoint. A modified drift-diffusion model, which accounts for spin-current\ntransmission through the ferrimagnet, reveals that the dephasing length is\nabout 4-5 times longer in nearly compensated CoGd than in ferromagnetic metals.\nThis finding suggests that antiferromagnetic order can mitigate spin dephasing\n-- in a manner analogous to spin echo rephasing for nuclear and qubit spin\nsystems -- even in structurally disordered alloys at room temperature. We also\nfind evidence that transverse spin current interacts more strongly with the Co\nsublattice than the Gd sublattice. Our results provide fundamental insights\ninto the interplay between spin current and antiferromagnetic order, which are\ncrucial for engineering spin torque effects in ferrimagnetic and\nantiferromagnetic metals."
    },
    {
        "anchor": "Unoccupied states of individual silver clusters and chains on Ag(111): Size-selected silver clusters on Ag(111) were fabricated with the tip of a\nscanning tunneling microscope. Unoccupied electron resonances give rise to\nimage contrast and spectral features which shift toward the Fermi level with\nincreasing cluster size. Linear assemblies exhibit higher resonance energies\nthan equally sized compact assemblies. Density functional theory calculations\nreproduce the observed energies and enable an assignment of the resonances to\nhybridized atomic 5s and 5p orbitals with silver substrate states.",
        "positive": "Thermal annealing of sputtered Nb3Sn and V3Si thin films for\n  superconducting radio-frequency cavities: Nb3Sn and V3Si thin films are promising candidates as thin films for the next\ngeneration of superconducting radio-frequency (SRF) cavities. However,\nsputtered films often suffer from stoichiometry and strain issues during\ndeposition and post annealing. In this study, we explore the structural and\nchemical effects of thermal annealing, both in-situ and post-sputtering, on\nDC-sputtered Nb3Sn and V3Si films of varying thickness on Nb or Cu substrates,\nextending from our initial studies [1]. Through annealing at 950 {\\deg}C, we\nsuccessfully enabled recrystallization of 100 nm thin Nb3Sn films on Nb\nsubstrate with stoichiometric and strain-free grains. For 2 um thick films, we\nobserved the removal of strain and a slight increase in grain size with\nincreasing temperature. Annealing enabled a phase transformation from unstable\nto stable structure on V3Si films, while we observed significant Sn loss in 2\num thick Nb3Sn films after high temperature anneals. We observed similar Sn and\nSi loss on films atop Cu substrates during annealing, likely due to Cu-Sn and\nCu-Si phase generation and subsequent Sn and Si evaporation. These results\nencourage us to refine our process to obtain high-quality sputtered films for\nSRF use."
    },
    {
        "anchor": "Condensed Multiwalled Carbon Nanotubes as Super Fibers: The ultra-low intershell shear strength in carbon nanotubes (CNTs) has been\nthe primary obstacle to applications of CNTs as mechanical reinforcements. In\nthis paper we propose a new CNT-system composed of comprising of coaxial\ncylindrical shells of sp2-bonded carbons with condensed intershell spacings.\nOur atomistic calculations show that such condensed multiwalled carbon\nnanotubes (CMWNTs) can greatly enhance intershell shear strengths by several\norders, and can simultaneously generate higher tensile strengths and moduli\nrespectively than those of ordinary CNTs. It has further shown that CMWNTs can\nmaintain thermally stable up to 2,000 K. By taking advantage of the primary\nenhancement mechanism of CMWNTs, a method of producing CMWNTs is therefore\nproposed tentatively. It is believed that CMWNTs featured with those properties\ncan be taken as excellent candidates of super fibers for creating space\nelevators.",
        "positive": "Efficient and improved prediction of the band offsets at semiconductor\n  heterojunctions from meta-GGA density functionals: Accurate theoretical prediction of the band offsets at interfaces of\nsemiconductor heterostructures can often be quite challenging. Although density\nfunctional theory has been reasonably successful to carry out such calculations\nand efficient and accurate semilocal functionals are desirable to reduce the\ncomputational cost. In general, the semilocal functionals based on the\ngeneralized gradient approximation (GGA) significantly underestimate the bulk\nband gaps. This, in turn, results in inaccurate estimates of the band offsets\nat the heterointerfaces. In this paper, we investigate the performance of\nseveral advanced meta-GGA functionals in the computational prediction of band\noffsets at semiconductor heterojunctions. In particular, we investigate the\nperformance of r2SCAN (revised strongly-constrained and appropriately-normed\nfunctional), rMGGAC (revised semilocal functional based on cuspless hydrogen\nmodel and Pauli kinetic energy density functional), mTASK (modified Aschebrock\nand K\\\"ummel meta-GGA functional), and LMBJ (local modified Becke-Johnson)\nexchange-correlation functionals. Our results strongly suggest that these\nmeta-GGA functionals for supercell calculations perform quite well, especially,\nwhen compared to computationally more demanding GW calculations. We also\npresent band offsets calculated using ionization potentials and electron\naffinities, as well as band alignment via the branch point energies. Overall,\nour study shows that the aforementioned meta-GGA functionals can be used within\nthe DFT framework to estimate the band offsets in semiconductor\nheterostructures with predictive accuracy."
    },
    {
        "anchor": "Thermal effects on fracture and brittle-to-ductile transition: The fracture behavior of brittle and ductile materials can be strongly\ninfluenced by thermal fluctuations, especially in micro- and nano-devices as\nwell as in rubberlike and biological materials. However, temperature effects,\nin particular on the brittle-to-ductile transition, still require a deeper\ntheoretical investigation. As a step in this direction we propose a theory,\nbased on equilibrium statistical mechanics, able to describe the temperature\ndependent brittle fracture and brittle-to-ductile transition in prototypical\ndiscrete systems consisting in a lattice with breakable elements. Concerning\nthe brittle behavior, we obtain closed form expressions for the\ntemperature-dependent fracture stress and strain, representing a generalized\nGriffith criterion, ultimately describing the fracture as a genuine phase\ntransition. With regard to the brittle-to-ductile transition, we obtain a\ncomplex critical scenario characterized by a threshold temperature between the\ntwo fracture regimes (brittle and ductile), an upper and a lower yield\nstrength, and a critical temperature corresponding to the complete breakdown.\nTo show the effectiveness of the proposed models in describing thermal fracture\nbehaviors at small scales, we successfully compare our theoretical results with\nmolecular dynamics simulations of Si and GaN nanowires.",
        "positive": "Ab-initio calculations for structural properties of Zr-Nb alloys: Ab-initio calculations for the structural properties of Zr-Nb alloys at\ndifferent values of the niobium concentration are done at zero temperature.\nDifferent cases for Zr-Nb alloys with unit cells having BCC and HCP structures\nare considered. Optimal values of the lattice constants are obtained. Critical\nvalue for the niobium concentration corresponding to the structural\ntransformation HCP \\rightarrow BCC at zero temperature is determined.\nElectronic densities of states for two different structures with niobium\nconcentrations 12.5% and 25% having HCP and BCC structures, accordingly, are\nstudied."
    },
    {
        "anchor": "Branching of negative streamers in free flight: We recently have shown that a negative streamer in a sufficiently high\nhomogeneous field can branch spontaneously due to a Laplacian instability,\nrather than approach a stationary mode of propagation with fixed radius. In our\nprevious simulations, the streamer started from a wide initial ionization seed\non the cathode. We here demonstrate in improved simulations that a streamer\nemerging from a single electron branches in the same way. In fact, though the\nevolving streamer is much more narrow, it branches after an even shorter\npropagation distance.",
        "positive": "A new room-temperature equation of state of Bi up to 260 GPa: At room temperature, bismuth undergoes several structural transitions with\nincreasing pressure before taking on a body-centered cubic (bcc) phase at\napproximately 8 GPa. The bcc structure is stable to the highest measured\npressure and its simplicity, along with its high compressibility and atomic\nnumber, make it an enticing choice as a pressure calibrant. We present three\ndata sets on the compression of bismuth in a diamond anvil cell in a neon\npressure medium, up to a maximum pressure of about 260 GPa. The use of a soft\npressure medium reduces deviatoric stress when compared to previous work. With\nan expanded pressure range, higher point density, and a decreased uniaxial\nstress component, we are able to provide more reliable equation of state (EOS)\nparameters. We also conduct density functional theory (DFT)\nelectronic-structure calculations that confirm the stability of the bcc phase\nat high pressure."
    },
    {
        "anchor": "A new route to spin-orbit torque engineering via oxygen manipulation: Spin transfer torques allow for electrical manipulation of magnetization at\nroom temperature, which is utilized to build future electronic devices such as\nspin transfer torque memories. Recent experiments have discovered that the\ncombination of the spin transfer torque with the spin Hall effect enables more\nefficient manipulation. A versatile control mechanism of such spin-orbit\ntorques is beneficial to envision device applications with competitive\nadvantages over the existing schemes. Here we report that the oxidation\nmanipulation of spin-orbit torque devices triggers a new mechanism, and the\nresulting torques are estimated to be about two times stronger than that of the\nspin Hall effect. Our result introduces an entirely new way to engineer the\nspin-orbit torques for device operation via oxygen manipulation. Combined with\nelectrical gating for the control of the oxygen content, our finding may also\npave the way for towards reconfigurable logic devices.",
        "positive": "Picosecond dynamics of hot carriers and phonons and scintillator\n  non-proportionality: We have developed a model describing the non-proportional response in\nscintillators based on non-thermalised carrier and phonon transport. We show\nthat the thermalization of e-h distributions produced in scintillators\nimmediately after photon absorption may take longer than the period over which\nthe non-proportional signal forms. The carrier and LO-phonon distributions\nduring this period remain non-degenerate at quasi-equilibrium temperatures far\nexceeding room temperature. We solve balance equations describing the energy\nexchange in a hot bipolar plasma of electrons/holes and phonons. Taking into\naccount dynamic screening we calculate the ambipolar diffusion coefficient at\nall temperatures. The non-proportional light yields calculated for NaI are\nshown to be consistent with experimental data. We discuss the implications of a\nnon-equilibrium model, comparing its predictions with a model based on the\ntransport of thermalised carriers. Finally, evidence for non-equilibrium\neffects is suggested by the shape of non-proportionality curve and wide\ndispersion in data observed in K-dip spectroscopy near the threshold. A\ncomparison of the predicted curves shows good agreement for deformation\npotential value in the range 7-8 eV."
    },
    {
        "anchor": "High resolution three dimensional structural microscopy by single angle\n  Bragg ptychography: We present an efficient method of imaging 3D nanoscale lattice behavior and\nstrain fields in crystalline materials with a new methodology -- three\ndimensional Bragg projection ptychography (3DBPP). In this method, the 2D\nsample structure information encoded in a coherent high-angle Bragg peak\nmeasured at a fixed angle is combined with the real-space scanning probe\npositions to reconstruct the 3D sample structure. This work introduces an\nentirely new means of three dimensional structural imaging of nanoscale\nmaterials and eliminates the experimental complexities associated with rotating\nnanoscale samples. We present the framework for the method and demonstrate our\napproach with a numerical demonstration, an analytical derivation, and an\nexperimental reconstruction of lattice distortions in a component of a\nnanoelectronic prototype device.",
        "positive": "Thermally-induced magnetic order from glassiness in elemental neodymium: Temperature in thermodynamics is synonymous with disorder, and responsible\nfor ultimately destroying ordered phases. Here, we show an unusual magnetic\ntransition where, with increasing the temperature of elemental neodymium,\nlong-range multi-Q magnetic order emerges from a self-induced spin glass. Using\ntemperature-dependent spin-polarized scanning tunneling microscopy, we\ncharacterize the local Q order in the spin-Q glass phase and quantify the\nemergence of long-range multi-Q order with increasing temperature. We develop\ntwo distinct analysis tools, which enable the quantification of the glass\ntransition temperature, based on measured spatially-dependent magnetization. We\ncompare these observations with atomic spin dynamics simulations, which\nreproduce the qualitative observation of a phase transition from a\nlow-temperature spin glass phase to an intermediate ordered multi-Q phase.\nThese simulations trace the origin of the unexpected high temperature order in\nweakened frustration driven by temperature-dependent sublattice correlations.\nThese findings constitute an example of order from disorder and provide a rich\nplatform to study magnetization dynamics in a self-induced spin glass."
    },
    {
        "anchor": "Establishing process-structure linkages using Generative Adversarial\n  Networks: The microstructure of material strongly influences its mechanical properties\nand the microstructure itself is influenced by the processing conditions. Thus,\nestablishing a Process-Structure-Property relationship is a crucial task in\nmaterial design and is of interest in many engineering applications. We develop\na GAN (Generative Adversarial Network) to synthesize microstructures based on\ngiven processing conditions. This approach is devoid of feature engineering,\nneeds little domain awareness, and can be applied to a wide variety of material\nsystems. Results show that our GAN model can produce high-fidelity multi-phase\nmicrostructures which have a good correlation with the given processing\nconditions.",
        "positive": "Hexagonal-to-base-centered-orthorhombic $4Q$ charge density wave order\n  in kagome metals KV$_3$Sb$_5$, RbV$_3$Sb$_5$, and CsV$_3$Sb$_5$: I search for the ground state structures of the kagome metals KV$_3$Sb$_5$,\nRbV$_3$Sb$_5$, and CsV$_3$Sb$_5$ using first principles calculations.\nGroup-theoretical analysis shows that there are seventeen different distortions\nthat are possible due to the phonon instabilities at the $M$\n$(\\frac{1}{2},0,0)$ and $L$ $(\\frac{1}{2},0,\\frac{1}{2})$ points in the\nBrilouin zone of the parent $P6/mmm$ phase of these materials. I generated\nthese structures for the three compounds and performed full structural\nrelaxations that minimize the atomic forces and lattice stresses. I find that\nthe $Fmmm$ phase with the order parameter $M_1^+$ $(a,0,0)$ $+$ $L_2^-$\n$(0,b,b)$ has the lowest energy among these possibilities in all three\ncompounds. However, the $Fmmm$ exhibits a dynamical instability at its $Z$\n$(0,0,1)$ point, which corresponds to the $A$ $(0,0,\\frac{1}{2})$ point in the\nparent $P6/mmm$ phase. Condensation of this instability leads to a\nbase-centered orthorhombic structure with the space group $Cmcm$ and $4Q$ order\nparameter $M_1^+$ $(a,0,0)$ $+$ $L_2^-$ $(0,b,b)$ $+$ $A_6^+$\n$(\\frac{1}{2}c,\\frac{-\\sqrt{3}}{2}c)$."
    },
    {
        "anchor": "An Investigation of Machine Learning Methods Applied to Structure\n  Prediction in Condensed Matter: Materials characterization remains a significant, time-consuming undertaking.\nGenerally speaking, spectroscopic techniques are used in conjunction with\nempirical and ab-initio calculations in order to elucidate structure. These\nexperimental and computational methods typically require significant human\ninput and interpretation, particularly with regards to novel materials.\nRecently, the application of data mining and machine learning to problems in\nmaterial science have shown great promise in reducing this overhead. In the\nwork presented here, several aspects of machine learning are explored with\nregards to characterizing a model material, titania, using solid-state Nuclear\nMagnetic Resonance (NMR). Specifically, a large dataset is generated,\ncorresponding to NMR $^{47}$Ti spectra, using ab-initio calculations for\ngenerated TiO$_2$ structures. Principal Components Analysis (PCA) reveals that\ninput spectra may be compressed by more than 90%, before being used for\nsubsequent machine learning. Two key methods are used to learn the complex\nmapping between structural details and input NMR spectra, demonstrating\nexcellent accuracy when presented with test sample spectra. This work compares\nSupport Vector Regression (SVR) and Artificial Neural Networks (ANNs), as one\nstep towards the construction of an expert system for solid state materials\ncharacterization.",
        "positive": "Magnetic Structure of CaBaCo4O7: Lifting of Geometrical Frustration\n  towards Ferrimagnetism: CaBaCo4O7 represents a new class of ferrimagnets whose structure is built up\nof CoO4 tetrahedra only, similarly to other members LnBaCo4O7 of the 114\nseries, forming an alternate stacking of kagome and triangular layers. Neutron\npowder diffraction reveals, that this compound exhibits the largest distortion\nwithin the 114 series, characterized by a strong buckling of the kagome layers.\nDifferently from all other members it shows charge ordering, with Co2+ sitting\non two sites (Co2, Co3) and mixed valent cobalt Co3+/Co2+L sitting on two other\nsites (Co1, Co4). The unique ferrimagnetic structure of this cobaltite at 4 K\ncan be described as the assemblage of ferrimagnetic triple chains (Co1 Co2 Co3)\nrunning perpendicular to the kagome layers, ferromagnetically coupled within\nthe layers, and antiferromagnetically coupled with a fourth cobalt species Co4.\nThe lifting of the geometrical frustration towards ferrimagnetism, which\nappears in spite of the triangular topology of the cobalt lattice, is explained\nby the very large structural distortion, charge ordering phenomena and large\ncobalt valence compared to other LnBaCo4O7 oxides."
    },
    {
        "anchor": "On the extrinsic piezoelectricity: This work presents a continuation of our last paper, concerning the theory of\nthe response of an antiparallel domain structure in a plate-like electroded\nsample to external electric field. The theory is based on the exact formula for\nfree energy of the system, formed of a central ferroelectric part, isolated\nfrom electrodes (with a defined potential difference) by a surface layers. Our\ncalculations are applicable also to thin films. It is usual to use the term\n`extrinsic' for the contribution of domain walls displacement to macroscopic\nproperties of a sample. In our last paper we discussed the extrinsic\ncontribution to permittivity. In this work we concentrate on extrinsic\ncontribution to piezoelectric coefficients in ferroelectrics which are\nsimultaneously ferroelastics. As an example, we calculate the extrinsic\ncontribution to d_36 piezoelectric coefficient of RbH2PO4, that was recently\nmeasured in a wide range of temperature below Curie point.",
        "positive": "Tunable Electronic Structure and Magnetic Coupling in Strained\n  Two-Dimensional Semiconductor MnPSe3: The electronic structures and magnetic properties of strained monolayer\nMnPSe3 are investigated systematically by first-principles calculations. It is\nfound that the magnetic ground state (GS) of monolayer MnPSe3 can be\nsignificantly affected by biaxial strain engineering, while the semiconducting\ncharacteristics are well preserved. Owing to the sensitivity of the magnetic\ncoupling towards the structural deformation, a biaxial tensile strain about 13%\ncan lead to an antiferromagnetic-ferromagnetic (AFM-FM) transition. The\nunderlying physical mechanism of strain-dependent magnetic stability is mainly\nattributed to the competition effect of direct AFM interaction and indirect FM\nsuperexchange interaction between the nearest-neighbor (NN) two Mn atoms. In\naddition, we find that FM MnPSe3 is an intrinsic half semiconductor with a\nlarge spin exchange splitting in conduction bands, which is crucial for the\nspin-polarized carrier injection and detection. The sensitive interdependence\namong external stimuli, electronic structure and magnetic coupling suggests\nthat monolayer MnPSe3 can be a promising candidate in spintronics."
    },
    {
        "anchor": "Long-range Charger transfer in DNA through Polaron Diffusion: Recent experimental evidence shows that the pi-orbitals along the stacking of\nbase pairs can facilitate the long-range charge transfer in DNA. Proton motion\nin the base pair hydrogen bonds has also been found to affect the transfer\nrate. To explain this behavior we propose a model considering interactions of\ndoped charges with hydrogen bonds and vibrations in DNA. The charge trapped by\neither protons or vibrations can cause structural distortions leading to\npolaron formation. By further considering polaron diffusion in DNA we find that\nthe charge transfer rate derived from the diffusion coefficient is in agreement\nwith the experimental results.",
        "positive": "Electronic Properties of Vinylene-Linked Heterocyclic Conducting\n  Polymers: Predictive Design and Rational Guidance from DFT Calculations: The band structure and electronic properties in a series of vinylene-linked\nheterocyclic conducting polymers are investigated using density functional\ntheory (DFT). In order to accurately calculate electronic band gaps, we utilize\nhybrid functionals with fully periodic boundary conditions to understand the\neffect of chemical functionalization on the electronic structure of these\nmaterials. The use of predictive first-principles calculations coupled with\nsimple chemical arguments highlights the critical role that aromaticity plays\nin obtaining a low band gap polymer. Contrary to some approaches which\nerroneously attempt to lower the band gap by increasing the aromaticity of the\npolymer backbone, we show that being aromatic (or quinoidal) in itself does not\ninsure a low band gap. Rather, an iterative approach which destabilizes the\nground state of the parent polymer towards the aromatic \\leftrightarrow\nquinoidal level-crossing on the potential energy surface is a more effective\nway of lowering the band gap in these conjugated systems. Our results highlight\nthe use of predictive calculations guided by rational chemical intuition for\ndesigning low band gap polymers in photovoltaic materials."
    },
    {
        "anchor": "Gapless surface Dirac cone in antiferromagnetic topological insulator\n  MnBi$_2$Te$_4$: The recent discovered antiferromagnetic topological insulators in Mn-Bi-Te\nfamily with intrinsic magnetic ordering have rapidly drawn broad interest since\nits cleaved surface state is believed to be gapped, hosting the unprecedented\naxion states with half-integer quantum Hall effect. Here, however, we show\nunambiguously by using high-resolution angle-resolved photoemission\nspectroscopy that a gapless Dirac cone at the (0001) surface of MnBi$_2$Te$_4$\nexists between the bulk band gap. Such unexpected surface state remains\nunchanged across the bulk N\\'eel temperature, and is even robust against severe\nsurface degradation, indicating additional topological protection. Through\nsymmetry analysis and $\\textit{ab}$-$\\textit{initio}$ calculations we consider\ndifferent types of surface reconstruction of the magnetic moments as possible\norigins giving rise to such linear dispersion. Our results reveal that the\nintrinsic magnetic topological insulator hosts a rich platform to realize\nvarious topological phases such as topological crystalline insulator and\ntime-reversal-preserved topological insulator, by tuning the magnetic\nconfigurations.",
        "positive": "Nanophononic metamaterial: Thermal conductivity reduction by local\n  resonance: We present the concept of a locally resonant nanophononic metamaterial for\nthermoelectric energy conversion. Our configuration, which is based on a\nsilicon thin-film with a periodic array of pillars erected on one or two of the\nfree surfaces, qualitatively alters the base thin-film phonon spectrum due to a\nhybridization mechanism between the pillar local resonances and the underlying\natomic lattice dispersion. Using an experimentally-fitted\nlattice-dynamics-based model, we conservatively predict a drop in the\nmetamaterial thermal conductivity to as low as 50% of the corresponding uniform\nthin-film value despite the fact that the pillars add more phonon modes to the\nspectrum."
    },
    {
        "anchor": "Two Dimensional Functionalized Ultrathin Semi Insulating CaF2 Layer on\n  the Si(100) Surface at a Low Temperature for Molecular Electronic Decoupling\n  AH-2083 arXiv submit/3480305: The ability to precisely control the electronic coupling/decoupling of\nadsorbates from surfaces is an essential goal. It isimportant for fundamental\nstudies not only in surface science but alsoin several applied domains\nincluding, for example, miniaturizedmolecular electronic or for the development\nof various devices suchas nanoscale biosensors or photovoltaic cells. Here, we\nprovide atomic-scale experimental and theoretical investigations of a\nsemi-insulatinglayer grown on a silicon surface via its epitaxy with CaF2. We\nshowthat, following the formation of a wetting layer, the ensuing organizedunit\ncells are coupled to additional physisorbed CaF2molecules,periodically located\nin their surroundings. This configuration shapesthe formation of ribbons of\nstripes that functionalize the semi-conductor surface. The obtained assembly,\nhaving a monolayerthickness, reveals a surface gap energy of 3.2 eV. The\nadsorption of iron tetraphenylporphyrin molecules on the ribbons of stripes is\nused to estimate the electronic insulating properties of thisstructure via\ndifferential conductance measurements. Density functional theory (DFT)\nincluding several levels of complexity(annealing, DFT +U, and nonlocal van der\nWaals functionals) is employed to reproduce our experimental observations.\nOurfindings offer a unique and robust template that brings an alternative\nsolution to electronic semi-insulating layers on metal surfacessuch as NaCl.\nHence, CaF2/Si(100) ribbon of stripe structures, whose lengths can reach more\nthan 100 nm, can be used as aversatile surface platform for various\natomic-scale studies of molecular devices.",
        "positive": "Determination of the Number of Graphene Layers: Discrete Distribution of\n  the Secondary Electron Intensity Derived from Individual Graphene Layers: Using a scanning electron microscope, we observed a reproducible, discrete\ndistribution of secondary electron intensity stemming from an atomically thick\ngraphene film on a thick insulating substrate. The discrete distribution made\nit possible to uniquely relate the secondary electron intensity to the number\nof graphene layers. Furthermore, we found a distinct linear relationship\nbetween the relative secondary electron intensity from graphene and the number\nof layers, provided a low primary electron acceleration voltage was used. Based\non these observations, we propose a practical method to determine the number of\ngraphene layers in a sample. This method is superior to the conventional\noptical method in its capability to characterize graphene samples with\nsub-micrometer squares in area on various insulating substrates."
    },
    {
        "anchor": "`Ferroelectric' Metals Reexamined: Fundamental Mechanisms and Design\n  Considerations for New Materials: The recent observation of a ferroelectric-like structural transition in\nmetallic LiOsO$_3$ has generated a flurry of interest in the properties of\npolar metals. Such materials are thought to be rare because free electrons\nscreen out the long-range electrostatic forces that favor a polar structure\nwith a dipole moment in every unit cell. In this work, we question whether\nlong-range electrostatic forces are always the most important ingredient in\ndriving polar distortions. We use crystal chemical models, in combination with\nfirst-principles Density Functional Theory calculations, to explore the\nmechanisms of inversion-symmetry breaking in LiOsO$_3$ and both insulating and\nelectron-doped ATiO$_3$ perovskites, A = Ba, Sr, Ca. Although electrostatic\nforces do play a significant role in driving the polar instability of BaTiO$_3$\n(which is suppressed under electron doping), the polar phases of CaTiO$_3$ and\nLiOsO$_3$ emerge through a mechanism driven by local bonding preferences and\nthis mechanism is `resistant' to the presence of charge carriers. Hence, our\nresults suggest that there is no fundamental incompatibility between\nmetallicity and polar distortions. We use the insights gained from our\ncalculations to suggest design principles for new polar metals and promising\navenues for further research.",
        "positive": "Structural stability of the $B_{80}$ fullerene against defect formation: Using a systematic search algorithm we identify several types of point\ndefects in the boron fullerene with 80 atoms. All these point defect leave the\ncage structure intact. In addition the cage structure is also very stable with\nrespect to elastic deformations and addition or removal of atoms."
    },
    {
        "anchor": "Channels of oxygen diffusion in single crystal rubrene revealed: Electronic devices made from organic materials have the potential to support\na more ecologically friendly and affordable future. However, the ability to\nfabricate devices with well-defined and reproducible electrical and optical\nproperties is hindered by the sensitivity to the presence of chemical\nimpurities. Oxygen in particular is an impurity that can trap electrons and\nmodify conductive properties of some organic materials. Until now the\n3-dimensional profiling of oxygen species in organic semiconductors has been\nelusive and the effect of oxygen remains disputed. In this study we map out\nhigh-spatial resolution 3-dimensional distributions of oxygen inclusions near\nthe surface of single crystal rubrene, using Time of Flight Secondary Ion Mass\nSpectroscopy (TOF-SIMS). Channels of diffused oxygen, 'oxygen pillars', are\nfound extending from uniform oxygen inclusion layers at the surface. These\npillars extend to depths in excess of 1.8 {\\mu}m and act as an entry point for\noxygen to diffuse along the ab-plane of the crystal with at least some of the\ndiffused oxygen molecularly binding to rubrene. Our investigation of surfaces\nat different stages of evolution reveals the extent of oxygen inclusion, which\naffects rubrene's optical and transport properties, and is consequently of\nimportance for the reliability and longevity of devices.",
        "positive": "Radiation tolerance of two-dimensional material-based devices for space\n  applications: Characteristic for devices based on two-dimensional materials are their low\nsize, weight and power requirements. This makes them advantageous for use in\nspace instrumentation, including photovoltaics, batteries, electronics, sensors\nand light sources for long-distance quantum communication. Here, we present for\nthe first time a comprehensive study on combined radiation effects in earth's\natmosphere on various devices based on these nanomaterials. Using theoretical\nmodeling packages, we estimate relevant radiation levels and then expose\nfield-effect transistors, single-photon sources and monolayers as building\nblocks for future electronics to gamma-rays, protons and electrons. The devices\nshow negligible change in performance after the irradiation, suggesting robust\nsuitability for space use. Under excessive $\\gamma$-radiation, however,\nmonolayer WS$_2$ showed decreased defect densities, identified by an increase\nin photoluminescence, carrier lifetime and a change in doping ratio\nproportional to the photon flux. The underlying mechanism was traced back to\nradiation-induced defect healing, wherein dissociated oxygen passivates sulfur\nvacancies."
    },
    {
        "anchor": "High-resolution surface structure determination from bulk X-ray\n  diffraction data: The key to most surface phenomenon lies with the surface structure.\nParticularly it is the charge density distribution over surface that primarily\ncontrols overall interaction of the material with external environment. It is\ngenerally accepted that surface structure cannot be deciphered from\nconventional bulk X-ray diffraction data. Thus, when we intend to delineate the\nsurface structure in particular, we are technically compelled to resort to\nsurface sensitive techniques like High Energy Surface X-ray Diffraction\n(HESXD), Low Energy Electron Diffraction (LEED), Scanning Transmission Electron\nMicroscopy (STEM) and Grazing Incidence Small Angle X-ray Scattering (GISAXS).\nIn this work, using aspherical charge density models of crystal structures in\ndifferent molecular and extended solids, we show a convenient and complementary\nway of determining high-resolution experimental surface charge density\ndistribution from conventional bulk X-ray diffraction (XRD) data. The\nusefulness of our method has been validated on surface functionality of boron\ncarbide. While certain surfaces in boron carbide show presence of substantial\nelectron deficient centers, it is absent in others. Henceforth, a plausible\ncorrelation between the calculated surface structures and corresponding\nfunctional property has been identified.",
        "positive": "Kohn-Sham calculations combined with an average pair-density functional\n  theory: A recently developed formalism in which Kohn-Sham calculations are combined\nwith an ``average pair density functional theory'' is reviewed, and some new\nproperties of the effective electron-electron interaction entering in this\nformalism are derived. A preliminary construction of a fully self-consitent\nscheme is also presented in this framework."
    },
    {
        "anchor": "First-principles study of point defects in LiGaO2: The native point defects are studied in LiGaO2 using hybrid functional\ncalculations. We find that the relative energy of formation of the cation\nvacancies and the cation antisite defects depends strongly on the chemical\npotential conditions. The lowest energy defect is found to be the Ga_Li^2+\ndonor. It is compensated mostly by V_Li^-1and in part by Li_Ga^-2 in the more\nLi-rich conditions. The equilibrium carrier concentrations are found to be\nnegligible because the Fermi level is pinned deep in the gap and this is\nconsistent with insulating behavior in pure LiGaO2. The V_Ga has high energy\nunder all reasonable conditions. Both the Ga_Li and the V_O are found to be\nnegative U centers with deep 2+/0 transition levels.",
        "positive": "Anisotropic layer-by-layer carbon nanotubes/boron nitride/rubber\n  composite and its application in electromagnetic shielding: Multifunctional polymer composites with anisotropic properties are attracting\ninterests as they fulfil the growing demand of multitasking materials. In this\nwork, anisotropic polymer composites are fabricated by combining the\nlayer-by-layer (LBL) filtration method with the alternative assembling of\ncarbon nanotubes (CNTs) and hexagonal boron nitride flakes (hBN) on natural\nrubber latex particles (NR). The layered composites exhibit anisotropic thermal\nand electrical conductivities, which are tailored through the layer\nformulations. The best composite consists of four layers of NR modified with 8\nphr (parts per Hundred Rubber) CNTs (~7.4 wt%) and four alternated layers with\n12 phr hBN (~10.7 wt%). The composites exhibit an electromagnetic interference\n(EMI) shielding effectiveness of 22.41+-0.14 dB mm-1 at 10.3 GHz and a thermal\nconductivity equal to 0.25 W/(mK). Furthermore, when the layered composite is\nused as an electrical thermal heater the surface reaches a stable temperature\nof ~103 C in approx. 2 min, with an input bias of 2.5 V."
    },
    {
        "anchor": "Shallow carrier traps in hydrothermal ZnO crystals: Native and hydrogen-plasma induced shallow traps in hydrothermally grown ZnO\ncrystals have been investigated by charge-based deep level transient\nspectroscopy (Q-DLTS), photoluminescence and cathodoluminescence microanalysis.\nThe as-grown ZnO exhibits a trap state at 23 meV, while H-doped ZnO produced by\nplasma doping shows two levels at 22 meV and 11 meV below the conduction band.\nAs-grown ZnO displays the expected thermal decay of bound excitons with\nincreasing temperature from 7 K, while we observed an anomalous behaviour of\nthe excitonic emission in H-doped ZnO, in which its intensity increases with\nincreasing temperature in the range 140-300 K. Based on a multitude of optical\nresults, a qualitative model is developed which explains the Y line structural\ndefects, which act as an electron trap with an activation energy of 11 meV,\nbeing responsible for the anomalous temperature-dependent cathodoluminescence\nof H-doped ZnO.",
        "positive": "Quasiperiodic free electron metal layers: Using electron diffraction, we show that free electron metals such as sodium\nand potassium form a highly regular quasiperiodic monolayer on the fivefold\nsurface of icosahedral Al-Pd-Mn and that the quasiperiodicity propagates up to\nthe second layer in sodium. Our photoelectron spectroscopy results show that\nthe quasicrystalline alkali metal adlayer does not exhibit a pseudogap near the\nFermi level, thought to be charactersitic for the electronic structure of\nquasicrystalline materials. Calculations based on density functional theory\nprovide a model structure for the quasicrystalline alkali metal monolayer and\nconfirm the absence of a pseudogap."
    },
    {
        "anchor": "ScN/GaN($1\\bar{1}00$): a new platform for the epitaxy of twin-free\n  metal-semiconductor heterostructures: We study the molecular beam epitaxy of rock-salt ScN on the wurtzite\nGaN($1\\bar{1}00$) surface. To this end, ScN is grown on free-standing\nGaN($1\\bar{1}00$) substrates and self-assembled GaN nanowires that exhibit\n($1\\bar{1}00$) sidewalls. On both substrates, ScN crystallizes twin-free thanks\nto a specific epitaxial relationship, namely\nScN(110)[001]$||$GaN($1\\bar{1}00$)[0001], providing a congruent, low-symmetry\nGaN/ScN interface. The 13.1 % uniaxial lattice mismatch occurring in this\norientation mostly relaxes within the first few monolayers of growth by forming\na coincidence site lattice, where 7 GaN planes coincide with 8 ScN planes,\nleaving the ScN surface nearly free of extended defects. Overgrowth of the ScN\nwith GaN leads to a kinetic stabilization of the zinc blende phase, that\nrapidly develops wurtzite inclusions nucleating on {111} nanofacets, commonly\nobserved during zinc blende GaN growth. Our ScN/GaN($1\\bar{1}00$) platform\nopens a new route for the epitaxy of twin-free metal-semiconductor\nheterostructures made of closely lattice-matched GaN, ScN, HfN and ZrN\ncompounds.",
        "positive": "Thermal rectification in bulk materials with asymmetric shape: We investigate thermal rectification in a bulk material with a pyramid shape\nto elucidate shape dependence of the thermal rectification, and find that\nrectifying coefficient R is 1.35 for this shape, which is smaller than R=1.43\nfor a rectangular shape. This result is fully duplicated by our numerical\ncalculation based on Fourier's law. We also apply this calculation to a given\nshape, and show a possible way to increase R depending on the shape."
    },
    {
        "anchor": "The strength of the radial-breathing mode in single-walled carbon\n  nanotubes: We show by ab initio calculations that the electron-phonon coupling matrix\nelement M of the radial breathing mode in single-walled carbon nanotubes\ndepends strongly on tube chirality. For nanotubes of the same diameter the\ncoupling strength |M|^2 is up to one order of magnitude stronger for zig-zag\nthan for armchair tubes. For (n,m) tubes M depends on the value of (n-m) mod 3,\nwhich allows to discriminate semiconducting nano tubes with similar diameter by\ntheir Raman scattering intensity. We show measured resonance Raman profiles of\nthe radial breathing mode which support our theoretical predictions.",
        "positive": "Understanding electron correlation energy through density functional\n  theory: A curious behavior of electron correlation energy is explored. Namely, the\ncorrelation energy is the energy that tends to drive the system toward that of\nthe uniform electron gas. As such, the energy assumes its maximum value when a\ngradient of density is zero. As the gradient increases, the energy is\ndiminished by a gradient suppressing factor, designed to attenuate the energy\nfrom its maximum value similar to the shape of a bell curve. Based on this\nbehavior, we constructed a very simple mathematical formula that predicted the\ncorrelation energy of atoms and molecules. Combined with our proposed exchange\nenergy functional, we calculated the correlation energies, the total energies,\nand the ionization energies of test atoms and molecules; and despite the unique\nsimplicities, the functionals' accuracies are in the top tier performance,\ncompetitive to the B3LYP, BLYP, PBE, TPSS, and M11. Therefore, we propose that,\nas guided by the simplicities and supported by the accuracies, the correlation\nenergy is the energy that locally tends to drive the system toward the uniform\nelectron gas."
    },
    {
        "anchor": "Electronic structure of a subnanometer wide bottom-up fabricated\n  graphene nanoribbon: End states, band gap and dispersion: Angle-resolved two-photon photoemission and high-resolution electron energy\nloss spectroscopy are employed to derive the electronic structure of a\nsub-nanometer tomically precise quasi-one-dimensional graphene nanoribbon (GNR)\non Au(111). We resolved occupied and unoccupied electronic bands including\ntheir dispersion and determined the and gap, which possesses an unexpected\nlarge value of 5.1 eV. Supported by density functional theory (DFT)\ncalculations for the idealized infinite polymer and finite size oligomers an\nunoccupied non-dispersive electronic state with an energetic position in the\nmiddle of the band gap of the GNR could be identified. This state resides at\nboth ends of the ribbon (end state) and is only found in the finite sized\nsystems, i.e. the oligomers.",
        "positive": "Reducing the Possibility of Subjective Error in the Determination of the\n  Structure-Function-Based Effective Thermal Conductivity of Boards: The thermal response function given to a unit-step dissipation accurately\ncharacterizes the thermal system. Instead of the thermal response function the\nso-called structure function describing three-dimensional as the equivalent\nmodel of one-dimensional heat-spreading, created from the thermal response\nfunction with the help of complex mathematical procedures, is often used. Using\nthe structure function the partial thermal capacity and partial heat resistance\nof certain elements of the thermal system can be identified. If the geometrical\nmeasurements of a thermal system of simple geometry and homogeneous material\n(such as a homogeneous rod or board, etc.) are known, the coefficient of\nthermal conductivity of the material in question can be determined from two\npoints of the structure function at 2-5 per cent of accuracy. In this paper a\nmethod is presented which applies a wide range/section instead of two points of\nthe cumulative structure function to determine the thermal coefficient, thus\nreducing the subjective error deriving from the selection of the two points.\nThe above method is presented and illustrated in simulated as well as measured\nthermal transient responses."
    },
    {
        "anchor": "Hybrid improper ferroelectricity in a Multiferroic and Magnetoelectric\n  hybrid organic-inorganic perosvkite: There is great interest in hybrid organic-inorganic materials such as\nmetal-organic frameworks (MOFs). The compounds\n[C(NH$_{2}$)$_{3}$]M(HCOO)$_{3}$, where M=Cu$^{2+}$ or Cr$^{2+}$ are\nJahn-Teller (JT) active ions, are MOF with perovskite topology which\ncrystallizes in polar space group Pna2$_{1}$. In inorganic compounds,\noctahedral tilting and Jahn-Teller structural distortions are usually non-polar\ndistortions. However, in this MOF cooperative interactions between the\nantiferro-distortive distortions of the framework and the C(NH2)$_{3}$ organic\ncation via hydrogen bonding breaks the inversion symmetry and induces a\nferroelectric polarization.[Angew. Chem. Int. Ed. 50, 5847, 2011] Our ab-initio\nstudy supports the picture of an orbital-order-induced ferroelectricity, a rare\nexample of dipolar ordering caused by electronic degrees of freedom. The\nswitching of polarization direction implies the reversal of the weak\nferromagnetic component. The microscopic mechanism in this JT-based MOF with\nABX$_{3}$ perovskite structure displays a Hybrid Improper Ferroelectric (HIF)\nstate, arising from a trilinear coupling between different structural\ndeformations that comprise tilting, rotations and Jahn-Teller distortions of\nboth the BX$_{3}$ framework and the organic cation at the A sites. Since these\ndistortion modes in perovskite-inorganic compounds usually freeze-in at\nelevated temperatures, the trilinear coupling in MOF compounds may provide an\ninteresting route towards high-temperature multiferroicity. These results offer\nan important starting point for tailoring multiferroic properties in this\nemerging class of materials for various technological applications. In\nparticular, the high tunability of the ferroelectric polarization by means of\nthe modification of the organic A cation has been recently shown[J. Am. Chem.\nSoc. 135 18126 (2013)]",
        "positive": "Ab initio study of reflectance anisotropy spectra of a sub-monolayer\n  oxidized Si(100) surface: The effects of oxygen adsorption on the reflectance anisotropy spectrum (RAS)\nof reconstructed Si(100):O surfaces at sub-monolayer coverage (first stages of\noxidation) have been studied by an ab initio DFT-LDA scheme within a\nplane-wave, norm-conserving pseudopotential approach. Dangling bonds and the\nmain features of the characteristic RAS of the clean Si(100) surface are mostly\npreserved after oxidation of 50% of the surface dimers, with some visible\nchanges: a small red shift of the first peak, and the appearance of a distinct\nspectral structure at about 1.5 eV. The electronic transitions involved in the\nlatter have been analyzed through state-by-state and layer-by-layer\ndecompositions of the RAS. We suggest that new interplay between present\ntheoretical results and reflectance anisotropy spectroscopy experiments could\nlead to further clarification of structural and kinetic details of the Si(100)\noxidation process in the sub-monolayer range."
    },
    {
        "anchor": "Existence of the upper critical dimension of the Kardar-Parisi-Zhang\n  equation: The controversy whether or not he Kardar-Parisi-Zhang (KPZ) equation has an\nupper critical dimension (UCD) is going on for quite a long time. Some\napproximate integral equations for the two-point function served as an\nindication for the existence of a UCD, by obtaining a dimension, above which\nthe equation does not have a strong coupling solution. A surprising aspect of\nthese studies, however, is that variuos authors that considered the same\nequation produced large variations in the UCD. This caused some doubts\nconcerning the existence of a UCD. Here we revisit these calculations, describe\nthe reason for such large variations in the results of identical calculations,\nshow by a large-d expansion that indeed there exist a UCD and then obtain it\nnumerically by properly defining the integrals involved.",
        "positive": "First-principles energetics of water: a many-body analysis: Standard forms of density-functional theory (DFT) have good predictive power\nfor many materials, but are not yet fully satisfactory for solid, liquid and\ncluster forms of water. We use a many-body separation of the total energy into\nits 1-body, 2-body (2B) and beyond-2-body (B2B) components to analyze the\ndeficiencies of two popular DFT approximations. We show how machine-learning\nmethods make this analysis possible for ice structures as well as for water\nclusters. We find that the crucial energy balance between compact and extended\ngeometries can be distorted by 2B and B2B errors, and that both types of\nfirst-principles error are important."
    },
    {
        "anchor": "Tetragonal mixed system $Cs_2CuCl_{4-x}Br_x$ complemented by the\n  tetragonal phase realisation of $Cs_2CuCl_4$: Realisation of the tetragonal phase of $Cs_2CuCl_4$ is possible using\nspecific crystal growth conditions at a temperature below $281K$. This work\ndeals with the comparison of the magnetic susceptibility and the magnetization\nof this new tetragonal compound with the magnetic behaviour of tetragonal\n$Cs_2CuCl_{2.9}Br_{1.1}$, $Cs_2CuCl_{2.5}Br_{1.5}$, $Cs_2CuCl_{2.2}Br_{1.8}$\nand presents consistent results for such quasi $2-D$ antiferromagnets.\nStructural investigation at low temperature for $Cs_2CuCl_{2.2}Br_{1.8}$ shows\nno phase transition. The structure remains in the tetragonal symmetry $I4/mmm$.\nFurthermore, several magnetic reflections corresponding to the propagation\nvector $k = (0, 0, 0)$ are observed for this tetragonal compound through\nneutron diffraction experiments below the magnetic phase transition at $T_N =\n11.3K$ confirming its antiferromagnetic nature.",
        "positive": "Coherent and Incoherent Structural Dynamics in Laser-Excited Antimony: We investigate the excitation of phonons in photoexcited antimony and\ndemonstrate that the entire electron-lattice interactions, in particular\ncoherent and incoherent electron-phonon coupling, can be probed simultaneously.\nUsing femtosecond electron diffraction (FED) with high temporal resolution, we\nobserve the coherent excitation of the fully symmetric \\Ag\\ optical phonon mode\nvia the shift of the minimum of the atomic potential energy surface. Ab initio\nmolecular dynamics simulations on laser excited potential energy surfaces are\nperformed to quantify the change in lattice potential and the associated\nreal-space amplitude of the coherent atomic oscillations. Good agreement is\nobtained between the parameter-free calculations and the experiment. In\naddition, our experimental configuration allows observing the energy transfer\nfrom electrons to phonons via incoherent electron-lattice scattering events.\nThe electron-phonon coupling is determined as a function of electronic\ntemperature from our DFT calculations and the data by applying different models\nfor the energy-transfer."
    },
    {
        "anchor": "First-principles Calculations of Raman and Infrared Spectroscopy For\n  Phase Identification and Strain Calibration of Hafnia: Using density functional perturbation theory (DFPT) we computed the phonon\nfrequencies, Raman and IR activities of hafnia polymorphs (P4$_{2}$nmc,\nPca2$_{1}$, Pmn2$_{1}$, Pbca OI, brookite, and baddeleyite) for phase\nidentification. We investigated the evolution of Raman and IR activities with\nrespect to epitaxial strain and provide plots of frequency differences as a\nfunction of strain for experimental calibration and identification of the\nstrain state of the sample. We found Raman signatures of different hafnia\npolymorphs: $\\omega(A_{1g})=300$ cm$^{-1}$ for P4$_{2}$nmc, $\\omega(A_{1})=343$\ncm$^{-1}$ for Pca2$_{1}$, $\\omega(B_{2})=693$ cm$^{-1}$ for Pmn2$_{1}$,\n$\\omega(A_{g})=513$ cm$^{-1}$ for Pbca (OI), $\\omega(A_{g})=384$ cm$^{-1}$ for\nbrookite, and $\\omega (A_{g}) = 496$ cm$^{-1}$ for baddeleyite. We also\nidentified the Raman $B_{1g}$ mode, an anti-phase vibration of dipole moments,\n( $\\omega(B_{1g}) = 758$ cm$^{-1}$ for OI, $\\omega (B_{1g})= 784$ cm$^{-1}$ for\nbrookite) as the Raman signature of antipolar Pbca structures. We calculated a\nlarge splitting between longitudinal optical (LO) and transverse optical (TO)\nmodes ($\\Delta{\\omega_{\\text{LO-TO}}(A^{z}_{1})}=255$ cm$^{-1}$ in Pca2$_{1}$,\nand $\\Delta{\\omega_{\\text{LO-TO}}(A_{1})}=263$ cm$^{-1}$ in Pmn2$_{1}$) to the\nsame order as those observed in perovskite ferroelectrics, and related them to\nthe anomalously large Born effective charges of Hf atoms ($Z^{*}(\\text{Hf}) =\n5.54$).",
        "positive": "Monte Carlo study of the elastic interaction in heteropitaxial growth: We have studied the island size distribution and spatial correlation function\nof an island growth model under the effect of an elastic interaction of the\nform $1/r^{3}$. The mass distribution $P_n(t)$ that was obtained presents a\npronounced peak that widens with the increase of the total coverage of the\nsystem, $\\theta$. The presence of this peak is an indication of the\nself-organization of the system, since it demonstrates that some sizes are more\nfrequent than others. We have treated exactly the energy of the system using\nperiodic boundary conditions which were used in the Monte-Carlo simulations. A\ndiscussion about the effect of different factors is presented."
    },
    {
        "anchor": "Excitation-Dependent High-Lying Excitonic Exchange via Interlayer Energy\n  Transfer from Lower-to-Higher Bandgap 2D Material: High light absorption (~15%) and strong photoluminescence (PL) emission in\nmonolayer (1L) transition metal dichalcogenide (TMD) make it an ideal candidate\nfor optoelectronic applications. Competing interlayer charge (CT) and energy\ntransfer (ET) processes control the photocarrier relaxation pathways in TMD\nheterostructures (HSs). In TMDs, long-distance ET can survive up to several\ntens of nm, unlike the CT process. Our experiment shows that an efficient ET\noccurs from the 1Ls WSe2-to-MoS2 with an interlayer hBN, due to the resonant\noverlapping of the high-lying excitonic states between the two TMDs, resulting\nin enhanced HS MoS2 PL emission. This type of unconventional ET from the\nlower-to-higher optical bandgap material is not typical in the TMD HSs. With\nincreasing temperature, the ET process becomes weaker due to the increased\nelectron-phonon scattering, destroying the enhanced MoS2 emission. Our work\nprovides new insight into the long-distance ET process and its effect on the\nphotocarrier relaxation pathways.",
        "positive": "Dielectric transparency induced by hetero-phase oscillations near the\n  phase transition of relaxor ferroelectrics: We report the observation of a \"transparency window\" in the dielectric\nresonant absorption spectrum of the relaxor ferroelectric K1-xLixTaO3 (KLT) in\nthe vicinity of its weakly first order transition. This phenomenon is shown to\nbe conceptually similar to the electro-magnetically induced transparency (EIT)\nphenomenon observed in atomic vapors, which can be modeled classically by a\ndriven master -slave oscillator system. In KLT, it reveals the presence of\nmacroscopic hetero-phase fluctuations and provides unique information on the\nnature and mechanism of the phase transition in relaxors."
    },
    {
        "anchor": "Probing the Surface Polarization of Ferroelectric Thin Films by X-ray\n  Standing Waves: Understanding the mechanisms underlying a stable polarization at the surface\nof ferroelectric thin films is of particular importance both from a fundamental\npoint of view and to achieve control of the surface polarization itself. In\nthis study, it is demonstrated that the X-ray standing wave technique allows\nthe polarization near the surface of a ferroelectric thin film to be probed\ndirectly. The X-ray standing wave technique is employed to determine, with\npicometer accuracy, Ti and Ba atomic positions near the surface of three\ndifferently strained $\\mathrm{BaTiO_3}$ thin films grown on scandate\nsubstrates, with a $\\mathrm{SrRuO_3}$ film as bottom electrode. This technique\ngives direct access to atomic positions, and thus to the local ferroelectric\npolarization, within the first 3 unit cells below the surface. By employing\nX-ray photoelectron spectroscopy, a detailed overview of the oxygen-containing\nspecies adsorbed on the surface, upon exposure to ambient conditions, is\nobtained. The combination of structural and spectroscopic information allows us\nto conclude on the most plausible mechanisms that stabilize the surface\npolarization in the three samples under study. The different amplitude and\norientation of the local ferroelectric polarizations are associated with\nsurface charges attributed to the type, amount and spatial distribution of the\noxygen-containing adsorbates.",
        "positive": "Phase transition on the Si(001) clean surface prepared in UHV MBE\n  chamber: A study by high resolution STM and in situ RHEED: Pre-growth preparation of the Si(001) clean surface is a key process for\nGe/Si UHV MBE. It usually includes pre-cleaning by liquid etchants, thermal\npretreatment in UHV and removal of SiO2 or a different protective coat prior to\nMBE. Chemical pre-cleaning usually results in formation of the thin SiO2 film\nor the surface passivated by H. Depending on chemical pretreatment different\npurification processes are applied to prepare the clean surface in UHV. A\nstructure of the Si(001) surface which may affect MBE was studied by STM and\nRHEED. Experiments were carried out in UHV using the Riber SSC2 instrument\ncoupled with GPI-300 STM. Si wafers were either etched beforehand in the\nsolutions of RCA or HF and HNO3 mixture or passivated in the HF solutions. The\n(2x1) reconstruction was found to mainly arise in UHV after deoxidization\nprocesses such as high-temperature annealing or SiO2 removal by a weak flux of\nSi. The c(8x8) structure was also often observed by STM at room temperature and\nfound to occupy whole surface or a part of it depending on sample cooling rate\nand chemical pretreatment. The c(8x8) structure observed by STM was evidenced\nto correspond to (4x4) one in the RHEED patterns; the later replaced (2x1) when\nthe samples were cooled below 600C and turned out to be reversible with the\ntransition point of ~600C. A structural model of the c(8x8) surface and a\npathway of its formation in assumption of surface stress field self ordering\nare proposed."
    },
    {
        "anchor": "Calculated Magnetic and Electronic Properties of Pyrochlore Iridates: Using density functional theory and LDA+U method, we investigate magnetic and\nelectronic structure of Y$_{2}$Ir$_{2}$O$_{7}$ and rare-earth based pyrochlore\niridates. Our study reveals that the ground state is a non-collinear magnetic\ninsulating state. Due to strong spin-orbit coupling in Ir 5\\textit{d}, there is\nan unusual correlation between the bands near Fermi level and the magnetization\ndirection, resulting in a possibility of insulator-to-metal transition under\napplied magnetic field. This makes pyrochlore iridates a good candidate for\npossible magnetoressitance and magnetooptical applications.",
        "positive": "Multistep transition of diamond to warm dense matter state revealed by\n  femtosecond X-ray diffraction: Diamond bulk irradiated with a free-electron laser pulse of 6100 eV photon\nenergy, 5 fs duration, at the $\\sim 19-25$ eV/atom absorbed doses, is studied\ntheoretically on its way to warm dense matter state. Simulations with our\nhybrid code XTANT show disordering on sub-100 fs timescale, with the\ndiffraction peak (220) vanishing faster than the peak (111). The warm dense\nmatter formation proceeds as a nonthermal damage of diamond with the band gap\ncollapse triggering atomic disordering. Short-living graphite-like state is\nidentified during a few femtoseconds between the disappearance of (220) peak\nand the disappearance of (111) peak. The results obtained are compared with the\ndata from the recent experiment at SACLA, showing qualitative agreement.\nChallenges remaining for the accurate modeling of the transition of solids to\nwarm dense matter state and proposals for supplementary measurements are\ndiscussed in detail."
    },
    {
        "anchor": "Magnetic domains and domain wall pinning in two-dimensional ferromagnets\n  revealed by nanoscale imaging: Magnetic-domain structure and dynamics play an important role in\nunderstanding and controlling the magnetic properties of two-dimensional\nmagnets, which are of interest to both fundamental studies and\napplications[1-5]. However, the probe methods based on the spin-dependent\noptical permeability[1,2,6] and electrical conductivity[7-10] can neither\nprovide quantitative information of the magnetization nor achieve nanoscale\nspatial resolution. These capabilities are essential to image and understand\nthe rich properties of magnetic domains. Here, we employ cryogenic scanning\nmagnetometry using a single-electron spin of a nitrogen-vacancy center in a\ndiamond probe to unambiguously prove the existence of magnetic domains and\nstudy their dynamics in atomically thin CrBr$_3$. The high spatial resolution\nof this technique enables imaging of magnetic domains and allows to resolve\ndomain walls pinned by defects. By controlling the magnetic domain evolution as\na function of magnetic field, we find that the pinning effect is a dominant\ncoercivity mechanism with a saturation magnetization of about 26~$\\mu_B$/nm$^2$\nfor bilayer CrBr$_3$. The magnetic-domain structure and pinning-effect\ndominated domain reversal process are verified by micromagnetic simulation. Our\nwork highlights scanning nitrogen-vacancy center magnetometry as a quantitative\nprobe to explore two-dimensional magnetism at the nanoscale.",
        "positive": "Decoupling Bimolecular Recombination Mechanisms in Perovskite Thin Films\n  Using Photoluminescence Quantum Yield: We present a novel analytical model for analysing the spectral\nphotoluminescence quantum yield of non-planar semiconductor thin films. This\nmodel considers the escape probability of luminescence and is applied to\ntriple-cation perovskite thin films with a 1-Sun photoluminescence quantum\nyield approaching 25%. By using our model, we can decouple the internal\nradiative, external radiative, and non-radiative bi-molecular recombination\ncoefficients. Unlike other techniques that measure these coefficients\nseparately, our proposed method circumvents experimental uncertainties by\navoiding the need for multiple photoluminescence measurement techniques. We\nvalidate our model by comparing the extracted implied open-circuit voltage,\neffective luminescence escape probabilities, absorptivity, and absorption\ncoefficient with values obtained using established methods and found that our\nresults are consistent with previous findings. Next, we compare the implied\n1-Sun radiative open-circuit voltage and radiative recombination current\nobtained from our method with literature values. We then convert the implied\nopen-circuit voltage and implied radiative open-circuit voltage to the\ninjection-dependent apparent-effective and apparent-radiative carrier\nlifetimes, which allow us to decouple the different recombination coefficients.\nUsing this lifetime analysis, we predict the efficiency losses due to each\nrecombination mechanism. Our proposed analytical model provides a reliable\nmethod for analysing the spectral photoluminescence quantum yield of\nsemiconductor thin films, which will facilitate further research into the\nphotovoltaic properties of these materials."
    },
    {
        "anchor": "First principles theory of the nitrogen interstitial in hBN: a plausible\n  model for the blue emitter: Color centers in hexagonal boron nitride (hBN) have attracted considerable\nattention due to their remarkable optical properties enabling robust room\ntemperature photonics and quantum optics applications in the visible spectral\nrange. On the other hand, identification of the microscopic origin of color\ncenters in hBN has turned out to be a great challenge that hinders in-depth\ntheoretical characterization, on-demand fabrication, and development of\nintegrated photonic devices. This is also true for the blue emitter, which is\nan irradiation damage in hBN emitting at 436 nm wavelengths with desirable\nproperties. Here, we propose the negatively charged nitrogen split interstitial\ndefect in hBN as a plausible microscopic model for the blue emitter. To this\nend, we carry out a comprehensive first principles theoretical study of the\nnitrogen interstitial. We carefully analyze the accuracy of first principles\nmethods and show that the commonly used HSE hybrid exchange-correlation\nfunctional fails to describe the electronic structure of this defect. Using the\ngeneralized Koopman's theorem, we fine tune the functional and obtain a\nzero-phonon photoluminescence (ZPL) energy in the blue spectral range. We show\nthat the defect exhibits high emission rate in the ZPL line and features a\ncharacteristic phonon side band that resembles the blue emitter's spectrum.\nFurthermore, we study the electric field dependence of the ZPL and numerically\nshow that the defect exhibits a quadratic Stark shift for perpendicular to\nplane electric fields, making the emitter insensitive to electric field\nfluctuations in first order. Our work emphasize the need for assessing the\naccuracy of common first principles methods in hBN and exemplifies a workaround\nmethodology. Furthermore, our work is a step towards understanding the\nstructure of the blue emitter and utilizing it in photonics applications.",
        "positive": "X-ray absorption (XANES) and photoelectron spectroscopy (XPS) of gamma\n  irradiated Nd doped phosphate glass: This paper presents the X-ray absorption near edge structure (XANES) and\nX-ray photoelectron spectroscopic (XPS) studies of Nd doped phosphate glasses\nbefore and after gamma irradiation. The intensity and location of LIII edge\nwhite line peak of Nd are found to be dependent on the concentration of Nd as\nwell as on the ratio of O/Nd in the glass matrix. The decrease in the peak\nintensity of white line of XANES spectra and asymmetry in the profile of Nd\n3d5/2 peak of XPS after gamma irradiation clearly indicates that Nd3+ gets\nreduced to Nd2+ in the glass matrix, which increases with an increase in the\ndoses of irradiation. Sharpening of Nd 3d5/2 XPS profile indicates about the\ndeficiency of oxygen in the glass after gamma irradiation, which is supported\nby EDX measurement."
    },
    {
        "anchor": "Electric-field induced strange metal states and possible\n  high-temperature superconductivity in hydrogenated graphitic fibers: In this work, we have studied the effects from increasing the strength of the\napplied electric field on the charge transport of hydrogenated graphitic\nfibers. Resistivity measurements were carried out for direct currents in the nA\n- mA range and for temperatures from 1.9 K to 300 K. The high-temperature\nnon-ohmic voltage-current dependence is well described by the nonlinear random\nresistor network model applied to systems that are disordered at all scales.\nThe temperature-dependent resistivity shows linear, step-like transitions from\ninsulating to metallic states as well as plateau features. As more current is\nbeing sourced, the fiber becomes more conductive and thus the current density\ngoes up. The most interesting features is observed in high electric fields. As\nthe fiber is cooled, the resistivity first decreases linearly with the\ntemperature and then enters a plateau region at a temperature T ? 260 ? 280 K\nthat is field-independent. These observations on a system made out of carbon,\nhydrogen, nitrogen, and oxygen atoms suggest possible electric-field induced\nsuperconductivity with a high critical temperature that was predicted from\nstudying the role of chirality on the origin of life [1].",
        "positive": "Breakdown of the semi-classical conduction theory in approximants of the\n  octagonal tiling: We present numerical calculations of quantum transport in perfect octagonal\napproximants. These calculations include a Boltzmann (intra-band) contribution\nand a non-Boltzmann (inter-band) contribution. When the unit cell size of the\napproximant increases, the magnitude of Boltzmann terms decreases, whereas the\nmagnitude of non-Boltzmann terms increases. It shows that, in large\napproximants, the non-Boltzmann contributions should dominate the transport\nproperties of electrons. This confirms the break-down of the Bloch-Boltzmann\ntheory to understand the transport properties in approximants with very large\nunit cells, and then in quasicrystals, as found in actual Al-based\napproximants."
    },
    {
        "anchor": "Electronic structure of LaBr3 from quasi-particle self-consistent GW\n  calculations: Rare-earth based scintillators in general and lanthanum bromide (LaBr_3) in\nparticular represent a challenging class of materials due to pronounced\nspin-orbit coupling and subtle interactions between d and f states that cannot\nbe reproduced by standard density functional theory (DFT). Here a detailed\ninvestigation of the electronic band structure of LaBr_3 using the\nquasi-particle self-consistent GW (QPscGW) method is presented. This\nparameter-free approach is shown to yield an excellent description of the\nelectronic structure of LaBr_3. Specifically it is able to reproduce the band\ngap, the correct level ordering and spacing of the 4f and 5d states, as well as\nthe spin-orbit splitting of La-derived states. The QPscGW results are\nsubsequently used to benchmark several computationally less demanding\ntechniques including DFT+U, hybrid exchange-correlation functionals, and the\nG_0W_0 method. Spin-orbit coupling is included self-consistently at each QPscGW\niteration and maximally localized Wannier functions are used to interpolate\nquasi-particle energies. The QPscGW results provide an excellent starting point\nfor investigating the electronic structure of excited states, charge\nself-trapping, and activator ions in LaBr_3 and related materials.",
        "positive": "Electronic structures and magnetic orders of Fe-vacancies ordered\n  ternary iron selenides TlFe$_{1.5}$Se$_2$ and AFe$_{1.5}$Se$_2$ (A=K, Rb, or\n  Cs): By the first-principles electronic structure calculations, we find that the\nground state of the Fe-vacancies ordered TlFe$_{1.5}$Se$_2$ is a\nquasi-two-dimensional collinear antiferromagnetic semiconductor with an energy\ngap of 94 meV, in agreement with experimental measurements. This\nantiferromagnetic order is driven by the Se-bridged antiferromagnetic\nsuperexchange interactions between Fe moments. Similarly, we find that crystals\nAFe$_{1.5}$Se$_2$ (A=K, Rb, or Cs) are also antiferromagnetic semiconductors\nbut with a zero-gap semiconducting state or semimetallic state nearly\ndegenerated with the ground states. Thus rich physical properties and phase\ndiagrams are expected."
    },
    {
        "anchor": "Predicting Defect Stability and Annealing Kinetics in Two-Dimensional\n  PtSe$_2$ Using Steepest Entropy Ascent Quantum Thermodynamics: The steepest-entropy-ascent quantum thermodynamic (SEAQT) framework was used\nto calculate the stability of a collection of point defects in 2D PtSe$_2$ and\npredict the kinetics with which defects rearrange during thermal annealing. The\nframework provides a non-equilibrium, ensemble-based framework with a\nself-consistent link between mechanics (both quantum and classical) and\nthermodynamics. It employs an equation of motion derived from the principle of\nsteepest entropy ascent (maximum entropy production) to predict the time\nevolution of a set of occupation probabilities that define the states of a\nsystem undergoing a non-equilibrium process. The system is described by a\ndegenerate energy landscape of eigenvalues, and the entropy is found from the\noccupation probabilities and the eigenlevel degeneracies. Scanning tunneling\nmicroscopy was used to identify the structure and distribution of point defects\nobserved experimentally in a 2D PtSe$_2$ film. A catalog of observed defects\nincluded six unique point defects (vacancies and anti-site defects on Pt and Se\nsublattices) and twenty combinations of multiple point defects in close\nproximity. The defect energies were estimated with density functional theory\n(DFT), while the degeneracies, or density of states, for the 2D film with all\npossible combinations or arrangements of cataloged defects was constructed\nusing a non-Markovian Monte-Carlo approach (i.e., the\nReplica-Exchange-Wang-Landau algorithm) with a q-state Potts model. The energy\nlandscape and associated degeneracies were determined for a 2D PtSe$_2$ film\ntwo molecules thick and $30 \\times 30$ unit cells in area (total of 5400\natoms). The SEAQT equation of motion was applied to the energy landscape to\ndetermine how an arbitrary density and arrangement of the six defect types\nevolve during annealing.",
        "positive": "Evidence of a pressure-induced metallization process in monoclinic\n  VO$_2$: Raman and combined trasmission and reflectivity mid infrared measurements\nhave been carried out on monoclinic VO$_2$ at room temperature over the 0-19\nGPa and 0-14 GPa pressure ranges, respectively. The pressure dependence\nobtained for both lattice dynamics and optical gap shows a remarkable stability\nof the system up to P*$\\sim$10 GPa. Evidence of subtle modifications of V ion\narrangements within the monoclinic lattice together with the onset of a\nmetallization process via band gap filling are observed for P$>$P*. Differently\nfrom ambient pressure, where the VO$_2$ metal phase is found only in\nconjunction with the rutile structure above 340 K, a new room temperature\nmetallic phase coupled to a monoclinic structure appears accessible in the high\npressure regime, thus opening to new important queries on the physics of\nVO$_2$."
    },
    {
        "anchor": "Quantum size effects, multiple Dirac cones and edge states in ultrathin\n  Bi(110) films: The presence of inherently strong spin-orbit coupling in bismuth, its unique\nlayer-dependent band topology and high carrier mobility make it an interesting\nsystem for both fundamental studies and applications. Theoretically, it has\nbeen suggested that strong quantum size effects should be present in the\nBi(110) films, with the possibility of Dirac fermion states in the odd-bilayer\n(BL) films, originating from dangling $p_z$ orbitals and quantum-spin hall\n(QSH) states in the even-bilayer films. However, the experimental verification\nof these claims has been lacking. Here, we study the electronic structure of\nBi(110) films grown on a high-$T_c$ superconductor,\nBi$_2$Sr$_2$CaCu$_2$O$_{8+\\delta}$ (Bi2212) using angle-resolved photoemission\nspectroscopy (ARPES). We observe an oscillatory behavior of electronic\nstructure with the film thickness and identify the Dirac-states in the\nodd-bilayer films, consistent with the theoretical predictions. In the\neven-bilayer films, we find another Dirac state that was predicted to play a\ncrucial role in the QSH effect. In the low thickness limit, we observe several\nextremely one-dimensional states, probably originating from the edge-states of\nBi(110) islands. Our results provide a much needed experimental insight into\nthe electronic and structural properties of Bi(110) films.",
        "positive": "Minimal phase-field crystal modeling of vapor-liquid-solid coexistence\n  and transitions: A phase-field crystal model based on the density-field approach incorporating\nhigh-order interparticle direct correlations is developed to study\nvapor-liquid-solid coexistence and transitions within a single continuum\ndescription. Conditions for the realization of the phase coexistence and\ntransition sequence are systematically analyzed and shown to be satisfied by a\nbroad range of model parameters, demonstrating the high flexibility and\napplicability of the model. Both temperature-density and temperature-pressure\nphase diagrams are identified, while structural evolution and coexistence among\nthe three phases are examined through dynamical simulations. The model is also\nable to produce some temperature and pressure related material properties,\nincluding effects of thermal expansion and pressure on equilibrium lattice\nspacing, and temperature dependence of saturation vapor pressure. This model\ncan be used as an effective approach for investigating a variety of material\ngrowth and deposition processes based on vapor-solid, liquid-solid, and\nvapor-liquid-solid growth."
    },
    {
        "anchor": "Invertible Optical Nonlinearity in Epsilon-near-zero Materials: Epsilon-near-zero (ENZ) materials such as indium tin oxide (ITO), have\nrecently emerged as a new platform to enhance optical nonlinearities. Here we\nreport a theoretical and experimental study on the origin of nonlinearities in\nITO thin films that are dominated by two mechanisms based on intraband and\ninterband transitions. We show that there are two competing factors that\njointly contribute to a spectrally-invertible nonlinearity of ITO near its ENZ\nregion i.e. the non-parabolicity of the band structure that results in a larger\neffective mass in the intraband transition and the Fermi energy shift, which\ndetermines the free carrier density. Our work reveals the relationship between\nthe large nonlinearity and the intrinsic material properties of the ITO films.",
        "positive": "Growth and structural transitions of core-shell nanorods in\n  nanocrystalline Al-Ni-Y: Unique nanorod precipitates with a core-shell structure are found to nucleate\nfrom the grain boundaries of a bulk nanocrystalline Al-Ni-Y alloy fabricated\nvia powder consolidation, contributing significantly to stabilization and\nstrengthening. The local structure, chemistry, and evolution of these features\nduring annealing is reported here. In the as-consolidated state, the nanorods\ncan be either structurally ordered or disordered, yet a consistent chemical\npatterning is found where the core is primarily Al plus C while the shell is\nenriched with Y. As annealing time increases, more nanorods transform to an\nordered structure as they coarsen while the core composition remains unchanged.\nIn contrast, the shell chemistry transitions from Y-rich to Ni-rich with longer\nannealing treatments, most likely due to the different diffusivities of Y and\nNi in Al. Moreover, a spatial and chemical correlation between the nanorods and\namorphous complexions is observed, suggesting that these complexions serve as\npreferential nucleation sites."
    },
    {
        "anchor": "Spin-fluctuations drive the inverse magnetocaloric effect in Mn5Si3: Inelastic neutron scattering measurements were performed on single crystals\nof the antiferromagnetic compound Mn5Si3 in order to investigate the relation\nbetween the spin dynamics and the magneto-thermodynamic properties. It is shown\nthat among the two stable antiferromagnetic phases of this compound, the high\ntemperature one has an unusual magnetic excitation spectrum where propagative\nspin-waves and diffuse spin-fluctuations coexist. Moreover, it is evidenced\nthat the inverse magnetocaloric effect of Mn5Si3, the cooling by adiabatic\nmagnetization, is associated with field induced spin-fluctuations.",
        "positive": "Influence of anisotropic magnetoresistance on nonlocal signals in\n  Si-based multi-terminal devices with Fe electrodes: We have investigated the influence of anisotropic magnetoresistance (AMR) on\nnonlocal signals in Si-based multi-terminal devices with ferromagnetic Fe\nelectrodes. The AMR of the Fe electrodes was found to have a significant\ninfluence on nonlocal signals when the in-plane device structure is not\noptimized. Moreover, realization of a pure spin current by spin diffusion was\nfound to be virtually impossible because of the electric potential distribution\nin the depth direction in the Si channel. Although apparent signals indicating\nthe spin-valve effect were not detected, we mainly present structural influence\non the electric potential distribution which is indispensable for the analyses\nof spin-dependent transport."
    },
    {
        "anchor": "Symmetries in TEM imaging of crystals with strain: TEM images of strained crystals often exhibit symmetries, the source of which\nis not always clear. To understand these symmetries we distinguish between\nsymmetries that occur from the imaging process itself and symmetries of the\ninclusion that might affect the image. For the imaging process we prove\nmathematically that the intensities are invariant under specific\ntransformations. A combination of these invariances with specific properties of\nthe strain profile can then explain symmetries observed in TEM images. We\ndemonstrate our approach to the study of symmetries in TEM images using\nselected examples in the field of semiconductor nanostructures such as quantum\nwells and quantum dots.",
        "positive": "Field dependent competing magnetic ordering in multiferroic Ni3V2O8: The geometrically frustrated magnet Ni3V2O8 undergoes a series of competing\nmagnetic ordering at low temperatures. Most importantly, one of the\nincommensurate phases has been reported to develop a ferroelectric correlation\ncaused by spin frustration. Here we report an extensive thermodynamic,\ndielectric and magnetic study on clean polycrystalline samples of this novel\nmultiferroic compound. Our low temperature specific heat data at high fields up\nto 14 Tesla clearly identify the development of a new magnetic field induced\nphase transition below 2 K that shows signatures of simultaneous electric\nordering. We also report temperature and field dependent dielectric constant\nthat enables us to quantitatively estimate the strength of magneto-electric\ncoupling in this improper ferroelectric material."
    },
    {
        "anchor": "Liberation of slave modes inside domain walls in multiferroic Cu-Cl\n  boracite: Domain walls (DWs), the two-dimensional boundaries between symmetry\nequivalent ferroic domains, are actively investigated due to their promise for\nnovel logic and memory devices. Moreover, they can be easily created, erased\nand reshaped at a low energy cost due to their high mobility and large\nelectrical conductivity. Most work so far has been focused on DWs in proper\nferroelectrics, where the primary order parameter, ferroelectric polarization,\ninterpolates between the values in the domains by either reducing to zero (in\nIsing-type DW) or rotating (Bloch type DW). Here we present a new member of DW\nfamily with a complex inner texture of slave order parameters inside the wall\nwhere the primary order parameter reduces to zero. Our first-principles-derived\nmodel predicts the existence of monopolar and toroidal polarization patterns.\nThe results enable large-scale phase field simulations of complex domain\npatterns in boracites and could inspire novel devices based on domain walls in\nimproper ferroelectrics.",
        "positive": "Concentration behavior of liquidus temperatures and undercooling of\n  Al-Cu-Co at normal pressure: Differential thermal analysis has been conducted for the Al-Cu-Co alloys with\nthe composition range of 15 at.% Co and 10 to 30 at.% Cu, and 25 at.% Co and\n2.5 to 20 at.% Co. The features of the formation of solid phases have been\nstudied during the crystallization in a crucible in the conditions of slow\ncooling (rate of cooling to 1 K s-1) at normal pressure. On the state diagram\nof the Al-Cu-Co system with 15 at.% Co and 25 at.% Cu the concentration\nsections have been built, which allows to determine the concentration ranges\nfrom which different phases are formed during the first stage of\ncrystallization. Along the boundaries of different phase regions, extrema are\nobserved on the liquidus line. The observed extrema on the liquidus lines and\nconcentration dependences of undercooling are associated with change in the\nchemical short-range order at the considered concentrations both in the liquid\nand solid states."
    },
    {
        "anchor": "Direct probing of strong magnon-photon coupling in a planar geometry: We demonstrate direct probing of strong magnon-photon coupling using\nBrillouin light scattering spectroscopy in a planar geometry. The magnonic\nhybrid system comprises a split-ring resonator loaded with epitaxial yttrium\niron garnet thin films of 200 nm and 2.46 $\\mu$m thickness. The Brillouin light\nscattering measurements are combined with microwave spectroscopy measurements\nwhere both biasing magnetic field and microwave excitation frequency are\nvaried. The cooperativity for the 200 nm-thick YIG films is 4.5, and larger\ncooperativity of 137.4 is found for the 2.46 $\\mu$m-thick YIG film. We show\nthat Brillouin light scattering is advantageous for probing the magnonic\ncharacter of magnon-photon polaritons, while microwave absorption is more\nsensitive to the photonic character of the hybrid excitation. A miniaturized,\nplanar device design is imperative for the potential integration of magnonic\nhybrid systems in future coherent information technologies, and our results are\na first stepping stone in this regard. Furthermore, successfully detecting the\nmagnonic hybrid excitation by Brillouin light scattering is an essential step\nfor the up-conversion of quantum signals from the optical to the microwave\nregime in hybrid quantum systems.",
        "positive": "Local Electronic Structure and Dynamics of Muon-Polaron Complexes in\n  Fe$_2$O$_3$: We perform detailed muon spin rotation ($\\mu$SR) measurements in the classic\nantiferromagnet Fe$_2$O$_3$ and explain the spectra by considering dynamic\npopulation and dissociation of charge-neutral muon-polaron complexes. We show\nthat charge-neutral muon states in Fe$_2$O$_3$, despite lacking the signatures\ntypical of charge-neutral muonium centers in nonmagnetic materials, have a\nsignificant impact on the measured $\\mu$SR frequencies and relaxation rates.\nOur identification of such polaronic muon centers in Fe$_2$O$_3$ suggests that\nisolated hydrogen (H) impurities form analogous complexes, and that H\ninterstitials may be a source of charge carrier density in Fe$_2$O$_3$."
    },
    {
        "anchor": "Comparison between Grating Imaging and Transient Grating Techniques on\n  Measuring Carrier Diffusion in Semiconductor: Optical grating technique, where optical gratings are generated via light\ninference, has been widely used to measure charge carrier and phonon transport\nin semiconductors. In this paper, compared are three types of transient optical\ngrating techniques: transient grating diffraction, transient grating\nheterodyne, and grating imaging, by utilizing them to measure carrier diffusion\ncoefficient in a GaAs/AlAs superlattice. Theoretical models are constructed for\neach technique to extract the carrier diffusion coefficient, and the results\nfrom all three techniques are consistent. Our main findings are: (1) the\ntransient transmission change obtained from transient grating heterodyne and\ngrating imaging techniques are identical, even these two techniques originate\nfrom different detection principles; and (2) By adopting detection of\ntransmission change (heterodyne amplification) instead of pure diffraction, the\ngrating imaging technique (transient grating heterodyne) has overwhelming\nadvantage in signal intensity than the transient grating diffraction, with a\nsignal intensity ratio of 315:1 (157:1).",
        "positive": "Velocity Renormalization and Carrier Lifetime in Graphene from\n  Electron-Phonon Interaction: We present a first-principles investigation of the phonon-induced electron\nself-energy in graphene. The energy dependence of the self-energy reflects the\npeculiar linear bandstructure of graphene and deviates substantially from the\nusual metallic behavior. The effective band velocity of the Dirac fermions is\nfound to be reduced by 4-8%, depending on doping, by the interaction with\nlattice vibrations. Our results are consistent with the observed linear\ndependence of the electronic linewidth on the binding energy in photoemission\nspectra."
    },
    {
        "anchor": "Special Glass Structures for First Principles Studies of Bulk Metallic\n  Glasses: The atomic-level structure of bulk metallic glasses is a key determinant of\ntheir properties. An accurate representation of amorphous systems in\ncomputational studies has traditionally required large supercells that are\nunfortunately computationally demanding to handle using the most accurate ab\ninitio calculations. To address this, we propose to specifically design\nsmall-cell structures that best reproduce the local geometric descriptors\n(e.g., pairwise distances or bond angle distributions) of a large-cell\nsimulation. We rely on molecular dynamics (MD) driven by empirical potentials\nto generate the target descriptors, while we use reverse Monte Carlo (RMC)\nmethods to optimize the small-cell structure. The latter can then be used to\ndetermine mechanical and electronic properties using more accurate electronic\nstructure calculations. The method is implemented in the Metallic Amorphous\nStructures Toolkit (MAST) software package.",
        "positive": "Temperature induced Neutral to Ionic phase Transition of the charge\n  transfer crystal Tetrathiafulvalene-Fluoranil: The Temperature Induced Neutral to Ionic phase Transition (TI-NIT) is a rare\nphenomenon occurring in mixed stack charge transfer (CT) crystals made up of\nalternating $\\pi$-electron Donor (D) and Acceptor (A) molecules. We were able\nto grow crystals of Tetrathiafulvalene-Fluoranil (TTF-FA), and to show that it\nundergoes TI-NIT like the prototype CT crystal TTF-Chloranil. We characterized\nboth room and low T phases through IR and Raman spectroscopy and XRD,\ndemonstrating that while TTF-FA is quasi-neutral at room T, its ionicity jumps\nfrom 0.15 to 0.7 at low T, therefore crossing the Neutral-Ionic borderline. The\ntransition, occuring around 150K, is first order, with large thermal hysteresis\nand accompanied by crystal cracking. In the high T phase D and A molecules lie\non inversion center, i.e. the stacks are regular, whereas the low T phase is\ncharacterized by the loss of the inversion symmetry along the stack as the\nstacks are strongly dimerized and by the doubling of the unit cell."
    },
    {
        "anchor": "Laser Directly Written Junctionless In-plane-Gate Neuron Thin Film\n  Transistors with AND Logic Function: Junctionless oxide-based neuron thin-film transistors with in-plane-gate\nstructure are fabricated at room temperature with a laser scribing process. The\nneuron transistors are composed of a bottom ITO floating gate and multiples of\ntwo in-plane control gates. The control gates, coupling with the floating gate,\ncontrol the \"on\" and \"off\" of the transistor. Effective field-effect modulation\nof the drain current has been realized. AND logic is demonstrated on a dual\nin-plane gate neuron transistor. The developed laser scribing technology is\nhighly desirable in terms of the fabrication of high performance neuron\ntransistors with low-cost.",
        "positive": "Polar phonon anomalies in single crystalline TbScO3: Polarized infrared reflectivity spectra of a (110)-oriented TbScO3 single\ncrystal plate were measured down to 10 K. The number of observed polar phonons\nactive along the crystallographic c axis at low temperatures is much higher\nthan predicted by factor-group analysis for the orthorhombic Pbnm space group.\nMoreover, the lowest frequency phonons active in E||c as well as in E||[1-10]\npolarized spectra exhibit dramatic softening tending to a lattice instability\nat low temperatures. The dielectric permittivity at microwave frequencies does\nnot show any ferroelectric-like anomaly, but the dielectric loss exhibits a\nmaximum at 100 K. The origin of the discrepancy between the number of predicted\nand observed polar phonons as well as the tendency toward lattice instability\nare discussed. Magnetic measurements reveal an antiferromagnetic phase\ntransition near 3 K."
    },
    {
        "anchor": "Surface Stability of SrNbO$_{3+\u03b4}$ Grown by Hybrid Molecular Beam\n  Epitaxy: 4d transition metal oxides have emerged as promising materials for numerous\napplications including high mobility electronics. SrNbO$_{3}$ is one such\ncandidate material, serving as a good donor material in interfacial oxide\nsystems and exhibiting high electron mobility in ultrathin films. However, its\nsynthesis is challenging due to the metastable nature of the d$^{1}$ Nb$^{4+}$\ncation and the limitations in the delivery of refractory Nb. To date, films\nhave been grown primarily by pulsed laser deposition (PLD), but development of\na means to grow and stabilize the material via molecular beam epitaxy (MBE)\nwould enable studies of interfacial phenomena and multilayer structures that\nmay be challenging by PLD. To that end, SrNbO$_{3}$ thin films were grown using\nhybrid MBE for the first time using a tris(diethalamido)(tert-butylimido)\nniobium precursor for Nb and an elemental Sr source on GdScO$_{3}$ substrates.\nVarying thicknesses of insulating SrHfO$_{3}$ capping layers were deposited\nusing a hafnium tert-butoxide precursor for Hf on top of SrNbO$_{3}$ films to\npreserve the metastable surface. Grown films were transferred in vacuo for\nX-ray photoelectron spectroscopy to quantify elemental composition, density of\nstates at the Fermi energy, and Nb oxidation state. Ex situ studies by X-ray\nabsorption near edge spectra illustrates the SrHfO$_{3}$ capping plays an\nimportant role in preserving the Nb 4d$^{1}$ metastable charge state in\natmospheric conditions.",
        "positive": "A fast and reliable method for the calculation of band structure of\n  solids with hybrid functionals: A simple approximation within the framework of the hybrid methods for the\ncalculation of the electronic structure of solids is presented. By considering\nonly the diagonal elements of the perturbation operator (Hartree-Fock exchange\nminus semilocal exchange) calculated in the basis of the semilocal orbitals,\nthe computational time is drastically reduced, while keeping the accuracy of\nthe results obtained with hybrid functionals when applied without any\napproximations."
    },
    {
        "anchor": "Accessing the spin structure of buried electronic states: In spin- and angle-resolved photoemission spectroscopy (SARPES) the\nenergy-momentum dispersion of electronic states in crystalline solids is\nmeasured along with the spin direction of the photoemitted electrons. The\ntechnique therefore allows for mapping out a material's band structure in a\nspin resolved fashion. By conducting SARPES measurements using low-energy\nphotons, the spin sensitivity of the technique can be combined an increased\nbulk probe depth, provided by the large electron inelastic mean-free path at\nthese kinetic energies, to directly access the spin structure of electronic\nstates at buried interfaces. Here, we demonstrate this capability by using\nSARPES to determine the spin polarization of photoelectrons emitted from a\n6-nm-thick film of the topological insulator Bi$_2$Se$_3$ using photons with an\nenergy of 8.5 eV. By modelling the expected spin structure in the film, we show\nthat the complex spin polarization that is observed is the integrated spin\nsignal from spin-polarized states at the surface, bulk and buried interface\n(bottom surface) of the topological-insulator film. Our results therefore\nallows us to directly determine the spin texture of the buried Dirac interface\nstate. This capability is highly attractive for state-of-the art spectroscopic\nmeasurements of the spin-physics at play in quantum-material based or\nspintronic devices where spin-polarized interface states define the operational\nprinciple of the devices.",
        "positive": "Impact of the scattering physics on the power factor of complex\n  thermoelectric materials: We assess the impact of the scattering physics assumptions on the\nthermoelectric properties of five Co-based p-type half-Heusler alloys by\nconsidering full energy-dependent scattering times, versus the commonly\nemployed constant scattering time. For this, we employ DFT bandstructures and a\nfull numerical scheme that uses Fermi's Golden Rule to extract the momentum\nrelaxation times of each state at every energy, momentum, and band. We consider\nelectron-phonon scattering (acoustic and optical), as well as ionized impurity\nscattering, and evaluate the qualitative and quantitative differences in the\npower factors of the materials compared to the case where the constant\nscattering time is employed. We show that the thermoelectric power factors\nextracted from the two different methods differ in terms of i) their ranking\nbetween materials, ii) the carrier density where the peak power factor appears,\nand iii) their trends with temperature. We further show that the constant\nrelaxation time approximation smoothens out the richness in the bandstructure\nfeatures, thus limiting the possibilities of exploring this richness for\nmaterial design and optimization. These details are more properly captured\nunder full energy/momentum-dependent scattering time considerations. Finally,\nby mapping the conductivities extracted within the two schemes, we provide\nappropriate density-dependent constant relaxation times that could be employed\nas a fast first order approximation for extracting charge transport properties\nin the half-Heuslers we consider."
    },
    {
        "anchor": "CCD Thermoreflectance Thermography System: Methodology and Experimental\n  Validation: This work introduces a thermoreflectance-based system designed to measure the\nsurface temperature field of activated microelectronic devices at submicron\nspatial resolution with either a laser or a CCD camera. The article describes\nthe system, outlines the measurement methodology, and presents validation\nresults. The thermo-reflectance thermography (TRTG) system is capable of\nacquiring device surface temperature fields at up to 512x512 points with 0.2\n$\\mu$m resolution. The setup and measurement methodology are presented, along\nwith details of the calibration process required to convert changes in measured\nsurface reflectivity to absolute temperatures. To demonstrate the system's\ncapabilities, standard gold micro-resistors are activated and their surface\ntemperature fields are measured. The results of the CCD camera and our existing\nlaser-based measurement approaches are compared and found to be in very good\nagreement. Finally, the system is validated by comparing the temperatures\nobtained with the TRTG method with those obtained from electrical resistance\nmeasurements.",
        "positive": "Encoding multistate charge order and chirality in endotaxial\n  heterostructures: High-density phase change memory (PCM) storage is proposed for materials with\nmultiple intermediate resistance states, which have been observed in\n1$T$-TaS$_2$ due to charge density wave (CDW) phase transitions. However, the\nmetastability responsible for this behavior makes the presence of multistate\nswitching unpredictable in TaS$_2$ devices. Here, we demonstrate the\nfabrication of nanothick verti-lateral $H$-TaS$_2$/1$T$-TaS$_2$\nheterostructures in which the number of endotaxial metallic $H$-TaS$_2$\nmonolayers dictates the number of resistance transitions in 1$T$-TaS$_2$\nlamellae near room temperature. Further, we also observe optically active\nheterochirality in the CDW superlattice structure, which is modulated in\nconcert with the resistivity steps, and we show how strain engineering can be\nused to nucleate these polytype conversions. This work positions the principle\nof endotaxial heterostructures as a promising conceptual framework for\nreliable, non-volatile, and multi-level switching of structure, chirality, and\nresistance."
    },
    {
        "anchor": "Cooling Dynamics of Photoexcited Carriers in Si Studied by Using Optical\n  Pump and Terahertz Probe Spectroscopy: We investigated the photoexcited carrier dynamics in Si by using optical pump\nand terahertz probe spectroscopy in an energy range between 2 meV and 25 meV.\nThe formation dynamics of excitons from unbound e-h pairs was studied through\nthe emergence of the 1s-2p transition of excitons at 12 meV (3 THz). We\nrevealed the thermalization mechanism of the photo-injected hot carriers\n(electrons and holes) in the low temperature lattice system by taking account\nof the interband and intraband scattering of carriers with acoustic and optical\nphonons. The overall cooling rate of electrons and holes was numerically\ncalculated on the basis of a microscopic analysis of the phonon scattering\nprocesses, and the results well account for the experimentally observed carrier\ncooling dynamics. The long formation time of excitons in Si after the above-gap\nphotoexcitation is reasonably accounted for by the thermalization process of\nphotoexcited carriers.",
        "positive": "Direct measurements of the magnetocaloric effect in pulsed magnetic\n  fields: The example of the Heusler alloy Ni$_{50}$Mn$_{35}$In$_{15}$: We have studied the magnetocaloric effect (MCE) in the shape-memory Heusler\nalloy Ni$_{50}$Mn$_{35}$In$_{15}$ by direct measurements in pulsed magnetic\nfields up to 6 and 20 T. The results in 6 T are compared with data obtained\nfrom heat-capacity experiments. We find a saturation of the inverse MCE,\nrelated to the first-order martensitic transition, with a maximum adiabatic\ntemperature change of $\\Delta T_{ad} = -7$ K at 250 K and a conventional\nfield-dependent MCE near the second-order ferromagnetic transition in the\naustenitic phase. The pulsed magnetic field data allow for an analysis of the\ntemperature response of the sample to the magnetic field on a time scale of\n$\\sim 10$ to 100 ms which is on the order of typical operation frequencies (10\nto 100 Hz) of magnetocaloric cooling devices. Our results disclose that in\nshape-memory alloys the different contributions to the MCE and hysteresis\neffects around the martensitic transition have to be carefully considered for\nfuture cooling applications."
    },
    {
        "anchor": "Thermodynamics and kinetics of core-shell versus appendage\n  co-precipitation morphologies: An example in the Fe-Cu-Mn-Ni-Si system: What determines precipitate morphologies in co-precipitating alloy systems?\nWe focus on alloys of two precipitating phases, with precipitates of the\nfast-precipitating phase acting as heterogeneous nucleation sites for a second\nphase manifesting slower kinetics. We study a FeCuMnNiSi alloy using the\ncombination of atom probe tomography and kinetic Monte Carlo simulations. It is\nshown that the interplay between interfacial and ordering energies, plus active\ndiffusion paths, strongly affect the selection of core-shell verses appendage\nmorphologies. Specifically, the ordering energy reduction of the MnNiSi phase\nheterogeneously nucleated on a pre-existing copper-rich precipitate exceeds the\nenergy penalty of a predominantly Fe/Cu interface, leading to initial\nappendage, rather than core-shell, formation. Diffusion of Mn, Ni and Si around\nand through the Cu core towards the ordered phase results in subsequent\nappendage growth. We further show that in cases with higher primary precipitate\ninterface energies and/or suppressed ordering, the core-shell morphology is\nfavored.",
        "positive": "Speeding up all-electron real-time TDDFT demonstrated by the exciting\n  package: Currently, many ab initio codes are being prepared for exascale computing. A\nfirst and important step is to significantly improve the efficiency of existing\nimplementations by devising better algorithms that can accomplish the same\ntasks with enhanced scalability. This manuscript addresses this challenge for\nreal-time time-dependent density functional theory in the full-potential\nall-electron code exciting, with a focus on systems with reduced\ndimensionality. Following the strategy described here, calculations can run\norders of magnitude faster than before. We demonstrate this with the molecules\nH$_2$ and CO, achieving speedups between 98 to over 50,000. We also present an\nexample where conventional calculations would be particularly costly, namely\nthe inorganic/organic heterostructure of pyridine physisorbed on monolayer\nMoS$_2$."
    },
    {
        "anchor": "Rapid and reliable thickness identification of two-dimensional\n  nanosheets using optical microscopy: The physical and electronic properties of ultrathin two-dimensional (2D)\nlayered nanomaterials are highly related to their thickness. Therefore, the\nrapid and accurate identification of single- and few- to multi-layer nanosheets\nis essential to their fundamental study and practical applications. Here, a\nuniversal optical method has been developed for simple, rapid and reliable\nidentification of single- to quindecuple-layer (1L-15L) 2D nanosheets,\nincluding graphene, MoS2, WSe2 and TaS2, on Si substrates coated with 90 nm or\n300 nm SiO2. The optical contrast differences between the substrates and 2D\nnanosheets with different layer numbers were collected and tabulated, serving\nas a standard reference, from which the layer number of a given nanosheet can\nbe readily and reliably determined without using complex calculation nor\nexpensive instrument. Our general optical identification method will facilitate\nthe thickness-dependent study of various 2D nanomaterials, and expedite their\nresearch toward practical applications.",
        "positive": "Oxygen vacancies in N doped TiO2: Experiment and first principle\n  calculations: We have determined the electronic and atomic structure of N doped TiO2 using\na combination of hard x-ray photoelectron spectroscopy (HAXPES) and first-\nprinciples density functional theory calculations. Our results reveal that N\ndoping of TiO2 leads to the formation of oxygen vacancies and the combination\nof both N impurity and oxygen vacancies accounts for the observed visible light\ncatalytic behavior of N doped TiO2."
    },
    {
        "anchor": "Disorder Effects in La substituted ferrimagnetic Ca2FeMoO6 double\n  perovskite: Ca2-xLaxFeMoO6 double perovskite with La concentration x = 0 to 0.6 was\nsynthesized using solid state sintering route. The standard techniques of XRD,\nSEM and EDX were applied to characterize the material. Crystal structure of the\nsamples was stabilized in monoclinic phase with space group P2I/n and lattice\nexpansion was indicated with the increase of x. The increase of La\nconcentration gradually suppressed the coexisting minor secondary phase in the\nmaterial and simultaneously, EDX results indicated the accommodation of more Mo\natoms in the crystal structure. A significant modification in the surface\nmorphology of the material was noted from adhesive type surface for x = 0 to\nbrittle type surface with more grain boundary contributions for La doped\nsamples. We understand a significant change in magnetic properties (appearance\nof cluster glass component, reduction of magnetic moment and indication of\nhigher TC) and in electrical properties (reduction of metallic character) in\nterms of enhanced internal disorder in the material, introduced due to La\ndoping in double perovskite structure.",
        "positive": "Computational Synthesis of 2D Materials: A High-throughput Approach to\n  Materials Design: 2D materials find promising applications in next-generation devices, however,\nlarge-scale, low-defect, and reproducible synthesis of 2D materials remains a\nchallenging task. To assist in the selection of suitable substrates for the\nsynthesis of as-yet hypothetical 2D materials, we have developed an open-source\nhigh-throughput workflow package, $Hetero2d$, that searches for low-lattice\nmismatched substrate surfaces for any 2D material and determines the stability\nof these 2D-substrate heterostructures using density functional theory (DFT)\nsimulations. $Hetero2d$ automates the generation of 2D-substrate\nheterostructures, the creation of DFT input files, the submission and\nmonitoring of computational jobs on supercomputing facilities, and the storage\nof relevant parameters alongside the post-processed results in a MongoDB\ndatabase. We demonstrate the capability of $Hetero2d$ in identifying stable\n2D-substrate heterostructures for four 2D materials, namely $2H$-MoS$_2$, $1T$-\nand $2H$-NbO$_2$, and hexagonal-ZnTe, considering 50 cubic elemental\nsubstrates. We find Cu, Hf, Mn, Nd, Ni, Pd, Re, Rh, Sc, Ta, Ti, V, W, Y, and Zr\nsubstrates sufficiently stabilize the formation energies of these 2D materials,\nwith binding energies in the range of ~0.1 - 0.6 eV/atom. Upon examining the\n$z$-separation, the charge transfer, and the electronic density of states at\nthe 2D-substrate interface, we find a covalent type bonding at the interface\nwhich suggests that these substrates can be used as contact materials for the\n2D materials. $Hetero2d$ (https://github.com/cmdlab/Hetero2d) is available on\nGitHub as an open-source package under the GNU license."
    },
    {
        "anchor": "Nanotechnology and Quasicrystals: From self assembly to photonic\n  applications: After providing a concise overview on quasicrystals and their discovery more\nthan a quarter of a century ago, I consider the unexpected interplay between\nnanotechnology and quasiperiodic crystals. Of particular relevance are efforts\nto fabricate artificial functional micro- or nanostructures, as well as efforts\nto control the self-assembly of nanostructures, where current knowledge about\nthe possibility of having long-range order without periodicity can provide\nsignificant advantages. I discuss examples of systems ranging from artificial\nmetamaterials for photonic applications, through self-assembled soft matter, to\nsurface waves and optically-induced nonlinear photonic quasicrystals.",
        "positive": "Phase-Field Model with Reduced Interface Diffuseness: We minimized the interface diffuseness in the phase-field models by\nintroducing the parabolic double-well potential and localizing the solute\nredistribution (or latent heat release) into a narrow region within the\nphase-field interface. In spite of the parabolic potential with cusps, highly\nlocalized solute redistribution and discontinuous diffusivity function adopted\nin this model, it works remarkably well in numerical computations. The\ncomputations on dendritic solidification of an one-sided system yield\nquantitatively the same results with the anti-trapping model [A. Karma, Phys.\nRev. Lett. 87, 115701 (2001)], indicating the anomalous interfacial effects can\nbe effectively suppressed. This approach can be easily extended to the\nmulti-components or multi-phases system."
    },
    {
        "anchor": "Tuning the dynamics of chiral domain walls of ferrimagnetic films with\n  the magneto-ionic effect: The manipulation of magnetism with a gate voltage is expected to lead the way\ntowards the realization of energy-efficient spintronics devices and\nhigh-performance magnetic memories. Exploiting magneto-ionic effects under\nmicro-patterned electrodes in solid-state devices adds the possibility to\nmodify magnetic properties locally, in a non-volatile and reversible way.\nTuning magnetic anisotropy, magnetization and Dzyaloshinskii-Moriya interaction\nallows modifying at will the dynamics of non trivial magnetic textures such as\nskyrmions and chiral domain walls in magnetic race tracks. In this work, we\nillustrate efficient magneto-ionic effects in a ferrimagnetic Pt/Co/Tb stack\nusing a ZrO2 thin layer as a solid state ionic conductor. When a thin layer of\nterbium is deposited on top of cobalt, it acquires a magnetic moment that\naligns antiparallel to that of cobalt, reducing the effective magnetization.\nBelow the micro-patterned electrodes, the voltage-driven migration of oxygen\nions in a ZrO2 towards the ferrimagnetic stack partially oxidizes the Tb layer,\nleading to the local variation not only of the spontaneous magnetization, but\nalso of the effective magnetic anisotropy and of the Dzyaloshinskii-Moriya\ninteraction. This leads to a huge increase of the domain wall velocity, which\nvaries from 10 m/s in the pristine state to 250 m/s after gating. This\nnon-volatile and reversible tuning of the domain wall dynamics may lead to\napplications to reprogrammable magnetic memories or other spintronic devices.",
        "positive": "Origins of the hydrogen signal in atom probe tomography: Atom Probe Tomography (APT) analysis is being actively used to provide\nnear-atomic-scale information on the composition of complex materials in\nthree-dimensions. In recent years, there has been a surge of interest in the\ntechnique to investigate the distribution of hydrogen in metals. However, the\npresence of hydrogen in the analysis of almost all specimens from nearly all\nmaterial systems has caused numerous debates as to its origins and impact on\nthe quantitativeness of the measurement. It is often perceived that most H\narises from residual gas ionization, therefore affecting primarily materials\nwith a relatively low evaporation field. In this work, we perform systematic\ninvestigations to identify the origin of H residuals in APT experiments by\ncombining density-functional theory (DFT) calculations and APT measurements on\nan alkali and a noble metal, namely Na and Pt, respectively. We report that no\nH residual is found in Na metal samples, but in Pt, which has a higher\nevaporation field, a relatively high signal of H is detected. These results\ncontradict the hypothesis of the H signal being due to direct ionization of\nresidual H$_2$ without much interaction with the specimen's surface. Based on\nDFT, we demonstrate that alkali metals are thermodynamically less likely to be\nsubject to H contamination under APT-operating conditions compared to\ntransition or noble metals. These insights indicate that the detected H-signal\nis not only from ionization of residual gaseous H$_2$ alone, but is strongly\ninfluenced by material-specific physical properties. The origin of H residuals\nis elucidated by considering different conditions encountered during APT\nexperiments, specifically, specimen-preparation, transportation, and\nAPT-operating conditions by taking thermodynamic and kinetic aspects into\naccount."
    },
    {
        "anchor": "Effect of annealing on carrier density and Curie temperature in\n  epitaxial (Ga,Mn)As thin films: We report a clear correspondence between changes in the Curie temperature and\ncarrier density upon annealing in epitaxially grown (Ga,Mn)As layers with\nthicknesses in the range between 5 nm and 20 nm. The changes are dependent on\nthe layer thickness, indicating that the (Ga,Mn)As - GaAs interface has\nimportance for the physical properties of the (Ga,Mn)As layer. The\nmagnetoresistance shows additional features when compared to thick (Ga,Mn)As\nlayers, that are at present of unknown origin.",
        "positive": "Post-Cotunnite phase of TeO2: We have used first-principles density-functional-theory methods with a\nrandom-structure-searching technique to determine the structure of the\npreviously unidentified post-cotunnite phase of TeO2. Our calculations indicate\na transition from the cotunnite to post-cotunnite phase at 130 GPa. The\npredicted post-cotunnite structure has P2_1/m space group symmetry and its\ncalculated x-ray diffraction pattern is in good agreement with the available\nexperimental data. We find that the cotunnite phase re-enters at about 260 GPa."
    },
    {
        "anchor": "Structure and oxidation kinetics of the Si(100)-SiO2 interface: We present first-principles calculations of the structural and electronic\nproperties of Si(001)-SiO2 interfaces. We first arrive at reasonable structures\nfor the c-Si/a-SiO2 interface via a Monte-Carlo simulated annealing applied to\nan empirical interatomic potential, and then relax these structures using\nfirst-principles calculations within the framework of density-functional\ntheory. We find a transition region at the interface, having a thickness on the\norder of 20\\AA, in which there is some oxygen deficiency and a corresponding\npresence of sub-oxide Si species (mostly Si^+2 and Si^+3). Distributions of\nbond lengths and bond angles, and the nature of the electronic states at the\ninterface, are investigated and discussed. The behavior of atomic oxygen in\na-SiO2 is also investigated. The peroxyl linkage configuration is found to be\nlower in energy than interstitial or threefold configurations. Based on these\nresults, we suggest a possible mechanism for oxygen diffusion in a-SiO2 that\nmay be relevant to the oxidation process.",
        "positive": "Defect engineering and Fermi-level tuning in half-Heusler topological\n  semimetals: Three-dimensional topological semimetals host a range of interesting quantum\nphenomena related to band crossing that give rise to Dirac or Weyl fermions,\nand can be potentially engineered into novel quantum devices. Harvesting the\nfull potential of these materials will depend on our ability to position the\nFermi level near the symmetry-protected band crossings so that their exotic\nspin and charge transport properties become prominent in the devices. Recent\nexperiments on bulk and thin films of topological half-Heuslers show that the\nFermi level is far from the symmetry-protected crossings, leading to strong\ninterference from bulk bands in the observation of topologically protected\nsurface states. Using density functional theory calculations we explore how\nintrinsic defects can be used to tune the Fermi level in the two representative\nhalf-Heusler topological semimetals PtLuSb and PtLuBi. Our results explain\nrecent results of Hall and angle-resolved photoemission measurements. The\ncalculations show that Pt vacancies are the most abundant intrinsic defects in\nthese materials grown under typical growth conditions, and that these defects\nlead to excess hole densities that place the Fermi level significantly below\nthe expected position in the pristine material. Directions for tuning the Fermi\nlevel by tuning chemical potentials are addressed."
    },
    {
        "anchor": "High-throughput ab initio analysis of the Bi-In, Bi-Mg, Bi-Sb, In-Mg,\n  In-Sb, and Mg-Sb systems: Prediction and characterization of crystal structures of alloys are a key\nproblem in materials research. Using high-throughput ab initio calculations we\nexplore the low-temperature phase diagrams for the following systems: {Bi-In,\nBi-Mg, Bi-Sb, In-Mg, In-Sb, and Mg-Sb}. For the experimentally observed phases\nin these systems we provide information about their stability at low\ntemperatures. Keywords: Binary Alloys, Ab initio, Intermetallics, Transition\nMetals, Structure Prediction, Phase Stability, Magnesium, Indium, Bismuth,\nAntimony.",
        "positive": "Comparison of three different self-interaction corrections for an\n  exactly solvable model system: A systematic comparison of three approximate self-interaction corrections\n(SICs), Perdew-Zunger SIC, Lundin-Eriksson SIC and extended Fermi-Amaldi SIC,\nis performed for a model Hamiltonian whose exact many-body solution and exact\nlocal-density approximation (LDA) are known. For each of the three proposals we\ncompare its implementation only for the potential, only for the energy, i.e., a\npost-LDA evaluation of the SIC energy), to none of them, i.e., a standard LDA\ncalculation) and to both. Each of the resulting 10 permutations of\nmethodologies is applied to 420 Hubbard chains differing in size, particle\nnumber and interaction strength. A statistical analysis of the resulting data\nset reveals trends and permits to assess the performance of each methodology.\nOverall, but not in each individual case, a post-LDA application of\nPerdew-Zunger SIC emerges as the recommended methodology."
    },
    {
        "anchor": "Ferromagnetic order in aged Co-doped TiO2 anatase nanopowders: Oxide based diluted magnetic semiconductor (DMS) materials have been a\nsubject of increasing interest due to reports of room temperature\nferromagnetism in several systems and their potential use in the development of\nspintronic devices. However, concerns on the stability of the magnetic\nproperties of different DMS systems have been raised. Their magnetic moment is\noften unstable, vanishing with a characteristic decay time of weeks or months,\nwhich precludes the development of real applications. This paper reports on the\nferromagnetic properties of two-year-aged Ti1-xCoxO2-{\\delta} reduced anatase\nnanopowders with different Co contents (0.03<x<0.10). Aged samples retain\nrather high values of magnetization, remanence and coercivity which provide\nstrong evidence for a quite preserved long-range ferromagnetic order. In what\nconcern Co segregation, some degree of metastability of the diluted Co doped\nanatase structure could be inferred in the case of the sample with the higher\nCo content.",
        "positive": "High quality sandwiched black phosphorus heterostructure and its quantum\n  oscillations: Two-dimensional (2D) materials, such as graphene and transition metal\ndichalcogenides have attracted great attention because of the rich physics and\npotential applications in next-generation nano-sized electronic devices.\nRecently, atomically thin black phosphorus (BP) has become a new member of the\n2D materials family with high theoretical mobility and tunable bandgap\nstructure. However, degradation of properties under atmospheric conditions and\nhigh-density charge traps in BP have largely limited its mobility (~400 cm2/Vs\nat room temperature) and thus restricted its future applications. Here, we\nreport the fabrication of stable BN-BP-BN heterostructures by encapsulating\natomically thin BP between hexagonal boron nitride (BN) layers to realize\nultraclean BN-BP interfaces which allow a record-high field-effect mobility\n~1350 cm2/Vs at room temperature and on-off ratios over 10^5. At low\ntemperatures, the mobility reaches ~2700 cm2/Vs and quantum oscillations in BP\n2D hole gas are observed at low magnetic fields. Importantly, the BN-BP-BN\nheterostructure can effectively avoid the quality degradation of BP in ambient\ncondition."
    },
    {
        "anchor": "Phase separation of a supersaturated nanocrystalline Cu Co alloy and its\n  influence on thermal stability: The thermal decomposition behavior, the microstructural evolution and its\ninfluence on the mechanical properties of a supersaturated Cu Co solid solution\nwith ~100 nm average grain size prepared by severe plastic deformation is\ninvestigated under non-isothermal and isothermal annealing conditions. Pure\nfine grained Cu and Co exhibit substantial grain growth upon annealing, whereas\nthe Cu Co alloy is thermally stable at the same annealing temperatures. The\nannealed microstructures are studied by independent characterization methods,\nincluding scanning electron microscopy, electron energy loss spectroscopy and\natom probe tomography. The phase separation process in the Cu Co alloy proceeds\nby the same mechanism, but on different length scales: a fine scaled spinodal\ntype decomposition is observed in the grain interior, simultaneously Co and Cu\nregions with a larger scale are formed near the grain boundary regions.\nSubsequent grain growth at higher annealing temperatures results in a\nmicrostructure consisting of the pure equilibrium phases. Such mechanisms can\nbe used to tailor nano structures to optimize certain properties.",
        "positive": "Doping of large-pore crown graphene nanomesh: Porous graphene structures, also termed graphene nanomeshes (GNMs), are\ngarnering increasing interest due to their potential application to important\ntechnologies such as chemical sensing, ion-filtration, and nanoelectronics.\nSemiconducting GNMs designed to have fractional eV band gaps are good\ncandidates for graphene-based electronics, provided that a mechanism for their\nstable and controlled doping is developed. Recent work has shown that\ncontrolled passivation of the edges of subnanometer pores and subsequent doping\nby atoms or molecules gives rise to {\\it p}- and {\\it n}-doped GNM structures.\nHowever, these structures are difficult to fabricate at the nanoscale. Here, we\nuse first principle calculations to study the effect of the pore size on the\ndoping physics of GNM structures with larger pores that can potentially host\nmore than a single dopant. We show that such doping mechanism is effective even\nfor pores with relatively large radii. We also study the effect of the number\nof dopants per pore on doping stability. We find that stable rigid band {\\it\nn}- and {\\it p}-doping emerges in such structures even if the dopants form a\nnano-cluster in the pore - rigid band doping is achieved in all {\\it n}- and\n{\\it p}-doping studied. Such doped large-pore GNM structures have potential\napplications as field effect transistors, and as transparent conducting\nelectrodes."
    },
    {
        "anchor": "Fermi-liquid theory of the surface impedance of a metal in a normal\n  magnetic field: In this paper we present detailed theoretical analysis of the frequency\nand/or magnetic field dependence of the surface impedance of a metal at the\nanomalous skin effect. We calculate the surface impedance in the presence of a\nmagnetic field directed along the normal to the metal surface. The effects of\nthe Fermi-liquid interactions on the surface impedance are studied. It is shown\nthat the cyclotron resonance in a normal magnetic field may be revealed {\\it\nonly and exclusively} in such metals whose Fermi surfaces include segments\nwhere its Gaussian curvature turns zero. The results could be applied to\nextract extra informations concerning local anomalies in the Fermi surface\ncurvature in conventional and quasi-two-dimensional metals.",
        "positive": "Highly sensitive NO2 sensors by pulsed laser deposition on graphene: Graphene as a single-atomic-layer material is fully exposed to environment\nand has therefore a great potential for creating of sensitive gas sensors.\nHowever, in order to realize this potential for different polluting gases,\ngraphene has to be functionalized - adsorption centers of different type and\nwith high affinity to target gases have to be created at its surface. In this\npresent work, modification of graphene by small amounts of laser ablated\nmaterials is introduced for this purpose as a versatile and precise tool. The\napproach was demonstrated with two very different materials chosen for pulsed\nlaser deposition (PLD), a metal (Ag) and a dielectric oxide (ZrO2). It was\nshown that the gas response and its recovery rate can be significantly enhanced\nby choosing the PLD target material and deposition conditions. The response to\nNO2 gas in air was amplified up to 40 times in case of PLD-modified graphene in\ncomparison with pristine graphene and reached 7-8% at 40 ppb of NO2 and 20-30%\nat 1 ppm of N2. These results were obtained after PLD in gas environment (5 x\n10-2 mbar oxygen or nitrogen) and atomic areal densities of deposited materials\nof were about 10 15 cm-2. The ultimate level of NO2 detection in air, as\nextrapolated from the experimental data obtained at room temperature under mild\nUV-excitation, was below 1 ppb."
    },
    {
        "anchor": "Multi-scale modelling to estimate spall parameters in metallic single\n  crystals: Modeling dynamics fracture in materials involves usage of hydrodynamic codes\nwhich solve basic conservation laws of mass, energy and momentum in space and\ntime. This requires appropriate models to handle elastic-plastic deformation,\nequation of state, material strength, and fracture. Nucleation and Growth (NAG)\ndamage model is a micro-physical model which computes amount of damage in the\nmaterial by accounting for phenomena like nucleation, growth and coalescence of\nvoids or cracks. The NAG model involves several material model parameters, such\nas nucleation threshold, growth threshold, etc. Traditionally these parameters\nare fitted to experimental void volume distributions. In the present paper we\nfit these parameters to molecular dynamics (MD) simulations of void nucleation\nand growth and use the fitted parameters in hydrodynamic simulations in a\nmulti-scale computational approach. Cubic metallic single crystals are\nsubjected to isotropic deformation and the nucleation of voids and their growth\nwere post-processed from the simulations. These results are used in an in-house\nParticle Swarm Optimization (PSO) code to obtain NAG parameters for materials\nof our interest. Using these parameters in a 1D hydrodynamic code developed\nin-house, fracture parameters such as spall strength and thickness are\nobtained. The results are validated with published experimental data for Mo, Nb\nand Cu which have been simulated using the multi-scale model. This paper\ndescribes the application of the multi-scale model to obtain the NAG fracture\nmodel parameters of Al and its spall data. The results are compared with\npublished experimental results in single crystal Al.",
        "positive": "Anisotropic intrinsic anomalous Hall effect in ordered 3dPt alloys: By performing first principles calculations we investigate the intrinsic\nanomalous Hall conductivity (AHC) and its anisotropy in ordered L1o FePt, CoPt\nand NiPt ferromagnets, and their intermediate alloys. We demonstrate that the\nAHC in this family of compounds depends strongly on the direction of the\nmagnetization in the crystal. We predict that such pronounced orientational\ndependence in combination with the general decreasing trend of the AHC when\ngoing from FePt to NiPt leads to a sign change of the AHC upon rotating the\nmagnetization direction in the crystal of CoPt alloy. We also suggest that for\na range of concentration x in Co(x)Ni(1-x)Pt alloy it is possible to achieve a\ncomplete quenching of the anomalous Hall current for a certain direction of the\nmagnetization in the crystal. By analyzing the spin-resolved AHC in 3dPt alloys\nwe endeavor to relate the overall trend of the AHC in these compounds to the\nchanges in their densities of d-states around the Fermi energy upon varying the\natomic number. Moreover, we show the generality of the phenomenon of\nanisotropic anomalous Hall effect by demonstrating its occurrence within the\nthree-band tight-binding model."
    },
    {
        "anchor": "Atomic scale spectral control of thermal transport in phononic crystal\n  superlattices: We present experimental and theoretical investigations of phonon thermal\ntransport in (LaMnO$_3$)$_m$/(SrMnO$_3$)$_n$ superlattices (LMO/SMO SLs) with\nthe thickness of individual layers $m,n = 3 - 10\\;$ u.c. and the thickness\nratio $m/n = 1, 2$. Optical transient thermal reflectivity measurements reveal\na pronounced difference in the thermal conductivity between SLs with $m/n = 1$,\nand SLs with $m/n = 2$. State-of-the art electron microscopy techniques and\nab-initio density functional calculations enables us to assign the origin of\nthis difference to the absence ($m/n = 1$) or presence ($m/n = 2$) of spatially\nperiodic, static oxygen octahedral rotation (OOR) inside the LMO layers. The\nexperimental data analysis shows that the effective thermal conductance of the\nLMO/SMO interfaces strongly changes from $0.3$ GW/m$^2$K for $m/n = 2$ SLs with\nOOR to a surprisingly large value of $1.8$ GW/m$^2$K for $m/n = 1$ SLs without\nOOR. An instructive lattice dynamical model rationalizes our experimental\nfindings as a result of coherent phonon transmission for $m/n = 1$ versus\ncoherent phonon blocking in SLs with $m/n = 2$. We briefly discuss the\npossibilities to exploit these results for atomic-scale engineering of a\ncrystalline phonon insulator. The thermal resistivity of this proposal for a\nthermal metamaterial surpasses the amorphous limit, although phonons still\npropagate coherently.",
        "positive": "Exciton energy-momentum map of hexagonal boron nitride: Understanding and controlling the way excitons propagate in solids is a key\nfor tailoring materials with improved optoelectronic properties. A fundamental\nstep in this direction is the determination of the exciton energy-momentum\ndispersion. Here, thanks to the solution of the parameter-free Bethe- Salpeter\nequation (BSE), we draw and explain the exciton energy-momentum map of\nhexagonal boron nitride (h-BN) in the first three Brillouin zones. We show that\nh-BN displays strong excitonic effects not only in the optical spectra at\nvanishing momentum $\\mathbf{q}$, as previously reported, but also at large\n$\\mathbf{q}$. We validate our theoretical predictions by assessing the\ncalculated exciton map by means of an inelastic x-ray scattering (IXS)\nexperiment. Moreover, we solve the discrepancies between previous experimental\ndata and calculations, proving then that the BSE is highly accurate through the\nwhole momentum range. Therefore, these results put forward the combination BSE\nand IXS as the tool of choice for addressing the exciton dynamics in complex\nmaterials."
    },
    {
        "anchor": "Near-Room Temperature Ferromagnetic Insulating State in Highly Distorted\n  LaCoO2.5 with CoO5 Square Pyramids: Dedicated control of oxygen vacancies is an important route to\nfunctionalizing complex oxide films. It is well-known that tensile strain\nsignificantly lowers the oxygen vacancy formation energy, whereas compressive\nstrain plays a minor role. Thus, atomically reconstruction by extracting oxygen\nfrom a compressive-strained film is challenging. Here we report an unexpected\nLaCoO2.5 phase with a zigzag-like oxygen vacancy ordering through annealing a\ncompressive-strained LaCoO3 in vacuum. The synergetic tilt and distortion of\nCoO5 square pyramids with large La and Co shifts are quantified using scanning\ntransmission electron microscopy. The large in-plane expansion of CoO5 square\npyramids weaken the crystal-field splitting and facilitated the ordered\nhigh-spin state of Co2+, which produces an insulating ferromagnetic state with\na Curie temperature of ~284 K and a saturation magnetization of ~0.25\n{\\mu}B/Co. These results demonstrate that extracting targeted oxygen from a\ncompressive-strained oxide provides an opportunity for creating unexpected\ncrystal structures and novel functionalities.",
        "positive": "Electronic bandstructure of superconducting KTaO3 (111) interfaces: Two-dimensional electron gases(2DEGs)based on KTaO3 are emerging as a\npromising platform for spin-orbitronics due to their high Rashba spin-orbit\ncoupling (SOC) and gate-voltage tunability. The recent discovery of a\nsuperconducting state in KTaO3 2DEGs now expands their potential towards\ntopological superconductivity. Although the band structure of KTaO3 surfaces of\nvarious crystallographic orientations has already been mapped using\nangle-resolved photoemission spectroscopy(ARPES), this is not the case for\nsuperconducting KTaO3 2DEGs. Here, we reveal the electronic structure of\nsuperconducting 2DEGs based on KTaO3 (111) single crystals through ARPES\nmeasurements. We fit the data with a tight-binding model and compute the\nassociated spin textures to bring insight into the SOC-driven physics of this\nfascinating system."
    },
    {
        "anchor": "Investigation of steady-state and time-dependent luminescence properties\n  of colloidal InGaP quantum dots: Quantum dots play a promising role in the development of novel optical and\nbiosensing devices. In this study, we investigated steady-state and\ntime-dependent luminescence properties of InGaP/ZnS core/shell colloidal\nquantum dots in a solution phase at room temperature. The steady state\nexperiments exhibited an emission maximum at 650 nm with full width at half\nmaximum of ~ 85 nm, and strong first-excitonic absorption peak at 600 nm. The\ntime-resolved luminescence measurements depicted a bi-exponential decay profile\nwith lifetimes of {\\tau}1\\sim 47 ns and {\\tau} 2\\sim 142 ns at the emission\nmaximum. Additionally, luminescence quenching and lifetime reduction due to\nresonance energy transfer between the quantum dot and an absorber are\ndemonstrated. Our results support the plausibility of using these InGaP quantum\ndots as an effective alternative to highly toxic conventional Cd or Pb based\ncolloidal quantum dots for biological applications.",
        "positive": "Machine-learned models for magnetic materials: We present a general framework for modeling materials using deep neural\nnetworks. Material represented by multidimensional characteristics (that mimic\nmeasurements) is used to train the neural autoencoder model in an unsupervised\nmanner. The encoder is trying to predict the material parameters of a\ntheoretical model, which is then used in a decoder part. The decoder, using the\npredicted parameters, reconstructs the input characteristics. The neural model\nis trained to capture a synthetically generated set of characteristics that can\ncover a broad range of material behaviors, leading to a model that can\ngeneralize on the underlying physics rather than just optimize the model\nparameters for a single measurement. After setting up the model we prove its\nusefulness in the complex problem of modeling magnetic materials in the\nfrequency and current (out-of-linear range) domains simultaneously."
    },
    {
        "anchor": "First-principles investigation of graphene fluoride and graphane: Different stoichiometric configurations of graphane and graphene fluoride are\ninvestigated within density functional theory. Their structural and electronic\nproperties are compared, and we indicate the similarities and differences among\nthe various configurations. Large differences between graphane and graphene\nfluoride are found that are caused by the presence of charges on the fluorine\natoms. A new configuration that is more stable than the boat configuration is\npredicted for graphene fluoride. We also perform GW calculations for the\nelectronic band gap of both graphene derivatives. These band gaps and also the\ncalculated Young's moduli are at variance with available experimental data.\nThis might indicate that the experimental samples contain a large number of\ndefects or are only partially covered with H or F.",
        "positive": "3D characterization of the primary Al3Sc phases in an Al-Sc alloy using\n  Synchrotron X-ray tomography and electron microscopy: The three-dimensional structures of the primary Al3Sc particles in an Al-2Sc\nmaster alloy were studied by synchrotron X-ray microtomography, scanning and\ntransmission electron microscopy. The Al3Sc phases were found to be a single\ncube and a cluster of cubes. The surface area, equivalent diameter of the Al3Sc\ncubes increased with the increasing of cube volume, but the specific surface\narea decreases. The primary Al3Sc cubes and Al-matrix have the same crystal\norientation, indicating that the Al3Sc phases are the heterogeneous nucleation\nsites for Al. The experimental results show that {\\alpha}-Al2O3 are the\npossible nucleation sites for the Al3Sc cubes."
    },
    {
        "anchor": "Efficient Calculation of Excitonic Effects in Solids Including\n  Approximated Quasiparticle Energies: In this work we present a new procedure to compute optical spectra including\nexcitonic effects and approximated quasiparticle corrections with reduced\ncomputational effort. The excitonic effects on optical spectra are included by\nsolving the Bethe-Salpeter equation, considering quasiparticle eigenenergies\nand respective wavefunctions obtained within DFT-1/2 method. The electron-hole\nladder diagrams are approximated by the screened exchange. To prove the\ncapability of the procedure, we compare the calculated imaginary part of the\ndielectric functions of Si, Ge, GaAs, GaP, GaSb, InAs, InP, and InSb with\nexperimental data. The energy position of the absorption peaks are correctly\ndescribed. The good agreement with experimental results together with the very\nsignificant reduction of computational effort makes the procedure suitable on\nthe investigation of optical spectra of more complex systems.",
        "positive": "The Removal of Single Layers from Multi-Layer Graphene by Low Energy\n  Electron Stimulation: The removal of single atomic layers from multi-layer graphene using a He\nplasma is reported. By applying sample biases of -60 and +60 V during He plasma\nexposure, layer removal is found to be due to electrons instead of He ions or\nneutrals in the plasma. The rate of layer removal depends on exposure time,\nsample bias and pre-annealing treatments. Optical contrast microscopy and\natomic force microscopy studies show that the removal of C atoms occurs\napproximately one layer at a time across the entire multi-layer sample with no\nobservable production of large pits or reduction in lateral dimensions. Layer\nremoval is proposed to arise from the electron-stimulated dissociation of C\natoms from the basal plane. This process differs from plasma techniques that\nuse reactive species to etch multi-layer graphene."
    },
    {
        "anchor": "Multiple structure and symmetry types in narrow temperature and magnetic\n  field ranges in two-dimensional Cr2Ge2Te6 crystal: Multiple structure and symmetry types and their transformations are\ndiscovered in quasi-two-dimensional (quasi-2D) Cr2Ge2Te6 crystal in\nsurprisingly very narrow temperature range of 2 K and magnetic field range of\n0.07 T using a homebuilt magnetic force microscope (MFM). A series of basic\ndomain patterns are extracted from the MFM images. Some of them seem unique to\n2-D materials as they are not observed in 3-D materials, such as self-fitting\ndisks, and fine ladder structure within Y-connected walls. Based on these\nfindings, a phase map is drawn for the magnetic phase structures. The symmetry\nof the patterns are discussed. The results are not only important in developing\nnew theories but also highly desirable in applications.",
        "positive": "Micromagnetic Modeling of the Magnetization Behavior of NiMnGa FMSMAs: The model calculations of the magnetization curves for the internally twinned\nNiMnGa ferromagnetic shape memory alloy are performed at the different volume\nfractions of twin variants. The method is based on the direct minimization of\nour new micromagnetic free energy model of FMSMAs taking into account both the\nmagnetic anisotropy energy and the magnetostatic energy contributions\nassociated with the laminated twin microstructure. The effect of the\nmagnetostatic energy is discussed in comparison with some early models, where\nthe magnetostatic energy was completely ignored."
    },
    {
        "anchor": "Atomistic simulations on ductile-brittle transition in <111> BCC Fe\n  nanowires: Molecular dynamics simulations have been performed to understand the\ninfluence of temperature on the tensile deformation and fracture behavior of\n$<$111$>$ BCC Fe nanowires. The simulations have been carried out at different\ntemperatures in the range 10-1000 K employing a constant strain rate of\n$1\\times$ $10^8$ $s^{-1}$. The results indicate that at low temperatures\n(10-375 K), the nanowires yield through the nucleation of a sharp crack and\nfails in brittle manner. On the other hand, nucleation of multiple 1/2$<$111$>$\ndislocations at yielding followed by significant plastic deformation leading to\nductile failure has been observed at high temperatures in the range 450-1000 K.\nAt the intermediate temperature of 400 K, the nanowire yields through\nnucleation of crack associated with many mobile 1/2$<$111$>$ and immobile\n$<$100$>$ dislocations at the crack tip and fails in ductile manner. The\nductile-brittle transition observed in $<$111$>$ BCC Fe nanowires is\nappropriately reflected in the stress-strain behavior and plastic strain at\nfailure. The ductile-brittle transition increases with increasing nanowire\nsize. The change in fracture behavior has been discussed in terms of the\nrelative variations in yield and fracture stresses and change in slip behavior\nwith respect to temperature. Further, the dislocation multiplication mechanism\nassisted by the kink nucleation from the nanowire surface observed at high\ntemperatures has been presented.",
        "positive": "Reduced graphene oxide thin films as ultrabarriers for organic\n  electronics: Encapsulation of electronic devices based on organic materials that are prone\nto degradation even under normal atmospheric conditions with hermetic barriers\nis crucial for increasing their lifetime. A challenge is to develop\n'ultrabarriers' that are impermeable, flexible, and preferably transparent.\nAnother important requirement is that they must be compatible with organic\nelectronics fabrication schemes (i.e. must be solution processable, deposited\nat room temperature and be chemically inert). Here, we report lifetime increase\nof 1,300 hours for poly(3-hexylthiophene) (P3HT) films encapsulated by uniform\nand continuous thin (~10 nm) films of reduced graphene oxide (rGO). This level\nof protection against oxygen and water vapor diffusion is substantially better\nthan conventional polymeric barriers such as CytopTM, which degrades after only\n350 hours despite being 400 nm thick. Analysis using atomic force microscopy,\nx-ray photoelectron spectroscopy and high resolution transmission electron\nmicroscopy suggest that the superior oxygen gas/moisture barrier property of\nrGO is due to the close interlayer distance packing and absence of pinholes\nwithin the impermeable sheets. These material properties can be correlated to\nthe enhanced lag time of 500 hours. Our results provide new insight for the\ndesign of high performance and solution processable transparent 'ultrabarriers'\nfor a wide range of encapsulation applications."
    },
    {
        "anchor": "BoltzTraP. A code for calculating band-structure dependent quantities: A program for calculating the semi-classic transport coefficients is\ndescribed. It is based on a smoothed Fourier interpolation of the bands. From\nthis analytical representation we calculate the derivatives necessary for the\ntransport distributions. The method is compared to earlier calculations, which\nin principle should be exact within Boltzmann theory, and a very convincing\nagreement is found.",
        "positive": "Equation of State of Hot, Dense Magnesium Derived with\n  First-PrinciplesComputer Simulations: Using two first-principles computer simulation techniques, path integral\nMonte-Carlo and density functional theory molecular dynamics, we derive the\nequation of state of magnesium in the regime of warm dense matter, with\ndensities ranging from 0.43 to 86.11~g/cm$^3$~and temperatures from 20,000 K to\n$5\\times10^8$~K. These conditions are relevant for the interiors of giant\nplanets and stars as well as for shock compression measurements and inertial\nconfinement fusion experiments. We study ionization mechanisms and electronic\nstructure of magnesium as a function of density and temperature. We show that\nthe L shell electrons 2s and 2p energy bands merge at high density. This\nresults into a gradual ionization of the L-shell with increasing density and\ntemperature. In this regard, Mg differs from MgO, which is also reflected in\nthe shape of its principal shock Hugoniot curve. For Mg, we predict a single\nbroad pressure-temperature region where the shock compression ratio is\napproximately 4.9. Mg thus differs from Si and Al plasma that exhibit two\nwell-separated compression maxima on the Hugoniot curve for L and K shell\nionizations. Finally we study multiple shocks and effects of preheat and\nprecompression."
    },
    {
        "anchor": "Relativistic Neel-order fields induced by electrical current in\n  antiferromagnets: We predict that a lateral electrical current in antiferromagnets can induce\nnon-equilibrium N\\'eel order fields, i.e. fields whose sign alternates between\nthe spin sublattices, which can trigger ultra-fast spin-axis reorientation.\nBased on microscopic transport theory calculations we identify staggered\ncurrent-induced fields analogous to the intra-band and to the intrinsic\ninter-band spin-orbit fields previously reported in ferromagnets with a broken\ninversion-symmetry crystal. To illustrate their rich physics and utility, we\nconsidered bulk Mn2Au with the two spin sublattices forming inversion partners,\nand a 2D square-lattice antiferromagnet with broken structural inversion\nsymmetry modelled by a Rashba spin-orbit coupling. We propose an AFM memory\ndevice with electrical writing and reading.",
        "positive": "Computational design of chemical nanosensors: Transition metal doped\n  single-walled carbon nanotubes: We present a general approach to the computational design of nanostructured\nchemical sensors. The scheme is based on identification and calculation of\nmicroscopic descriptors (design parameters) which are used as input to a\nthermodynamic model to obtain the relevant macroscopic properties. In\nparticular, we consider the functionalization of a (6,6) metallic armchair\nsingle-walled carbon nanotube (SWNT) by nine different 3d transition metal (TM)\natoms occupying three types of vacancies. For six gas molecules (N_{2}, O_{2},\nH_{2}O, CO, NH_{3}, H_{2}S) we calculate the binding energy and change in\nconductance due to adsorption on each of the 27 TM sites. For a given type of\nTM functionalization, this allows us to obtain the equilibrium coverage and\nchange in conductance as a function of the partial pressure of the \"target\"\nmolecule in a background of atmospheric air. Specifically, we show how Ni and\nCu doped metallic (6,6) SWNTs may work as effective multifunctional sensors for\nboth CO and NH_{3}. In this way, the scheme presented allows one to obtain\nmacroscopic device characteristics and performance data for nanoscale (in this\ncase SWNT) based devices."
    },
    {
        "anchor": "Quasiparticle and excitonic properties of monolayer SrTiO$_3$: Strontium titanate SrTiO$_3$ is one of the most studied and paradigmatic\ntransition metal oxides. Recently, a breakthrough has been achieved with the\nfabrication of freestanding SrTiO$_3$ ultrathin films down to the monolayer\nlimit. However, the many-body effects on the quasiparticle and optical\nproperties of monolayer SrTiO$_3$ remain unexplored. Using state-of-the-art\nmany-body perturbation theory in the GW approximation combined with the\nBethe-Salpeter equation, we study the quasiparticle band structure, optical and\nexcitonic properties of monolayer SrTiO$_3$. We show that quasiparticle\ncorrections significantly alter the band structure topology; however, the\nwidely used diagonal $G_0W_0$ approach yields unphysical band dispersions. The\ncorrect band dispersions are restored only by taking into account the\noff-diagonal elements of the self-energy. The optical properties are studied\nboth in the optical limit and for finite momenta by computing the electron\nenergy loss spectra. We find that the imaginary part of dielectric function at\nthe long wavelength limit is dominated by three strongly bound excitonic peaks\nand the direct optical gap is associated to a bright exciton state with a large\nbinding energy of 0.93 eV. We discuss the character of the excitonic peaks via\nthe contributing interband transitions, and reveal that the lowest bound\nexcitonic state becomes optical inactive for finite momenta along $\\Gamma$-M,\nwhile the other two excitonic peaks disperse to higher energies and eventually\nmerge for momenta close to M.",
        "positive": "Impurity-potential-induced gap at the Dirac point of topological\n  insulators with in-plane magnetization: The quantum anomalous Hall effect (QAHE), characterized by dissipationless\nquantized edge transport, relies crucially on a non-trivial topology of the\nelectronic bulk bandstructure and a robust ferromagnetic order that breaks\ntime-reversal symmetry. Magnetically-doped topological insulators (TIs) satisfy\nboth these criteria, and are the most promising quantum materials for realizing\nthe QAHE. Because the spin of the surface electrons aligns along the direction\nof magnetic-impurity exchange field, only magnetic TIs with an out-of-plane\nmagnetization are thought to open a gap at the Dirac point (DP) of the surface\nstates, resulting in the QAHE. Using a continuum model supported by atomistic\ntight-binding and first-principles calculations of transition-metal doped\nBi$_2$Se$_3$, we show that a surface-impurity potential generates an additional\neffective magnetic field which spin-polarizes the surface electrons along the\ndirection perpendicular to the surface. The predicted gap-opening mechanism\nresults from the interplay of this additional field and the in-plane\nmagnetization that shifts the position of the DP away from the $\\Gamma$ point.\nThis effect is similar to the one originating from the hexagonal warping\ncorrection of the bandstructure but is one order of magnitude stronger. Our\ncalculations show that in a doped TI with in-plane magnetization the\nimpurity-potential-induced gap at the DP is comparable to the one opened by an\nout-of-plane magnetization."
    },
    {
        "anchor": "Effects of sublattice symmetry and frustration on ionic transport in\n  garnet solid electrolytes: We use rigorous group-theoretic techniques and molecular dynamics to\ninvestigate the connection between structural symmetry and ionic conductivity\nin the garnet family of solid Li-ion electrolytes. We identify new ordered\nphases and order-disorder phase transitions that are relevant for conductivity\noptimization. Ionic transport in this materials family is controlled by the\nfrustration of the Li sublattice caused by incommensurability with the host\nstructure at non-integer Li concentrations, while ordered phases explain\nregions of sharply lower conductivity. Disorder is therefore predicted to be\noptimal for ionic transport in this and other conductor families with strong Li\ninteraction.",
        "positive": "Coverage-dependent magnetic and electronic properties of graphene with\n  Co adatoms: Decorating two-dimensional materials with transition-metal adatoms is an\neffective way to bring about new physical properties that are intriguing for\napplications in electronics and spintronics devices. Here, we systematically\nstudied the coverage-dependent magnetic and electronic properties of graphene\ndecorated by Co adatoms, based on first-principles calculations. We found that\nthe if the Co coverage is larger than 1/3 ML, the Co atoms will aggregate to\nform a Co monolayer and then a van der Waals bilayer system between the Co\nmonolayer and graphene forms. When the Co coverage is <= 1/3 ML, the Co adatom\nis spin polarized with spin moment varying from 1.1 ~ 1.4 {\\mu}B. The d(xz/yz)\nand d(xy/x2-y2 ) orbitals of Co hybridize significantly with the {\\pi} bands of\ngraphene, which generates a series of new bands in the energy range from -2 eV\nto 1 eV with respect to Dirac point of graphene. In most cases, the new bands\nnear the Fermi level lead to topological states characterized by the quantum\nanomalous Hall effect."
    },
    {
        "anchor": "Atomic-ordering-induced quantum phase transition between topological\n  crystalline insulator and Z2 topological insulator: Topological phase transition in a single material usually refers to\ntransitions between a trivial band insulator and a topological Dirac phase, but\nthe transition may also occur between different classes of topological Dirac\nphases. However, it is a fundamental challenge to realize quantum transition\nbetween Z2 nontrivial topological insulator (TI) and topological crystalline\ninsulator (TCI) in one material because Z2 TI and TCI are hardly both co-exist\nin a single material due to their contradictory requirement on the number of\nband inversions. The Z2 TIs must have an odd number of band inversions over all\nthe time-reversal invariant momenta, whereas, the newly discovered TCIs, as a\ndistinct class of the topological Dirac materials protected by the underlying\ncrystalline symmetry, owns an even number of band inversions. Here, take\nPbSnTe2 alloy as an example, we show that at proper alloy composition the\natomic-ordering is an effective way to tune the symmetry of the alloy so that\nwe can electrically switch between TCI phase and Z2 TI phase when the alloy is\nordered from a random phase into a stable CuPt phase. Our results suggest that\natomic-ordering provides a new platform to switch between different topological\nphases.",
        "positive": "Optical properties of monoclinic HfO2 studied by first-principles local\n  density approximation +U approach: The band structures and optical properties of monoclinic HfO2 are\ninvestigated by the local density approximation (LDA)+U approach. With the\non-site Coulomb interaction being introduced to 5d orbitals of Hf atom and 2p\norbitals of O atom, the experimental band gap is reproduced. The imaginary part\nof the complex dielectric function shows a small shoulder at the edge of the\nband gap, coinciding with the experiments. This intrinsic property of\ncrystallized monoclinic HfO2, which is absent in both the tetragonal phase and\ncubic phase, can be understood as a consequence of the reconstruction of the\nelectronic states near the band edge following the adjustment of the crystal\nstructure. The existence of a similar shoulder-like-structure in the monoclinic\nphase of ZrO2 is predicted."
    },
    {
        "anchor": "Possible surface plasmon polariton excitation under femtosecond laser\n  irradiation of silicon: The mechanisms of ripple formation on silicon surface by femtosecond laser\npulses are investigated. We demonstrate the transient evolution of the density\nof the excited free-carriers. As a result, the experimental conditions required\nfor the excitation of surface plasmon polaritons are revealed. The periods of\nthe resulting structures are then investigated as a function of laser\nparameters, such as the angle of incidence, laser fluence, and polarization.\nThe obtained dependencies provide a way of better control over the properties\nof the periodic structures induced by femtosecond laser on the surface of a\nsemiconductor material.",
        "positive": "Hybrid-order topology with tunable chiral hinge modes and unpinned Dirac\n  surface states in the altermagnetic insulator Eu$_{3}$In$_{2}$As$_{4}$: The exploration of magnetic topological states is instrumental in exploring\naxion electrodynamics and intriguing transport phenomena, such as the quantum\nanomalous Hall effect. Here, we predict that the recently-synthesized material\nEu$_{3}$In$_{2}$As$_{4}$ exhibits as both an axion insulator and a 3D\nStiefel-Whitney insulator with an altermagnetic order. When spins align in the\n$ab$ plane, we find an unpinned surface Dirac cone on the $ab$ plane and chiral\nhinge states along the $c$ direction, where hinge states can generate a\nhalf-quantized surface anomalous Hall effect on the $ac$ and $bc$ facets. When\nspins align along $c$, we observe a mirror-protected topological crystalline\ninsulator. Furthermore, the ferromagnetic phase, in which spins are aligned in\nthe same direction by an external in-plane magnetic field, presents an ideal\nWeyl semimetal with a single pair of type-I Weyl points and no extra Fermi\npocket. Our work predicts rich topological states tuned by magnetic structures\nin Eu$_{3}$In$_{2}$As$_{4}$, supporting the further study of the topological\ntransport and Majorana fermions in proximity to a superconductor."
    },
    {
        "anchor": "Integral Absorption of Microwave Power by Random-Anisotropy Magnets: We study analytically and numerically on lattices containing $10^5$ spins,\nthe integral absorption of microwaves by a random-anisotropy magnet, $\\int\nd\\omega P(\\omega)$. It scales as $D^2_R/J$ on the random-anisotropy strength\n$D_R$ and the strength of the ferromagnetic exchange $J$ in low-anisotropy\namorphous magnetic materials. At high anisotropy and in low-anisotropy\nmaterials sintered of sufficiently large ferromagnetic grains, the integral\npower scales linearly on $D_R$. The maximum bandwidth, combined with the\nmaximum absorption power, is achieved when the amorphous structure factor, or\ngrain size, is of an order of the domain wall thickness in a conventional\nferromagnet that is of the order of $(J/D_R)^{1/2}$ lattice spacings.",
        "positive": "FePc Adsorption on the Moir\u00e9 Superstructure of Graphene Intercalated\n  with a Co Layer: The moir\\'e superstructure of graphene grown on metals can drive the assembly\nof molecular architectures, as iron-phthalocyanine (FePc) molecules, allowing\nfor the production of artificial molecular configurations. A detailed analysis\nof the Gr/Co interaction upon intercalation (including a modelling of the\nresulting moir\\'e pattern) is performed here by density functional theory,\nwhich provides an accurate description of the template as a function of the\ncorrugation parameters. The theoretical results are a preliminary step to\ndescribe the interaction process of the FePc molecules adsorption on the Gr/Co\nsystem. Core level photoemission and absorption spectroscopies have been\nemployed to control the preferential adsorption regions of the FePc on the\ngraphene moir\\'e superstructure and the interaction of the central Fe ion with\nthe underlying Co. Our results show that upon molecular adsorption the distance\nof C atoms from the Co template mainly drives the strength of the\nmolecules-substrate interaction, thereby allowing for locally different\nelectronic properties within the corrugated interface."
    },
    {
        "anchor": "Extraordinary efficient spin-orbit torque switching in (W,\n  Ta)/epitaxial-Co60Fe40/TiN heterostructures: The giant spin Hall effect in magnetic heterostructures along with low spin\nmemory loss and high interfacial spin mixing conductance are prerequisites to\nrealize energy efficient spin torque based logic devices. We report giant spin\nHall angle (SHA) of 28.67 (5.09) for W (Ta) interfaced epi- Co60Fe40/TiN\nstructures. The spin-orbit torque switching current density (J_Crit) is as low\nas 1.82 (8.21) MA/cm2 in W (Ta)/Co60Fe40(t_CoFe)/TiN structures whose origin\nlies in the epitaxial interfaces. These structures also exhibit very low spin\nmemory loss and high spin mixing conductance. These extraordinary values of SHA\nand therefore ultra-low J_Crit in semiconducting industry compatible epitaxial\nmaterials combinations open up a new direction for the realization of energy\nefficient spin logic devices by utilizing epitaxial interfaces.",
        "positive": "Regulate the direct-indirect electronic band gap transition by\n  electron-phonon interaction in BaSnO3: The neutron powder diffraction, specific heat, thermal conductivity, and\nRaman scattering measurements were presented to study the interplays of\nlattice, phonons and electrons of the Sr-doping Ba1-xSrxSnO3 (x was less than\nor equal to 0.1). Although Ba1-xSrxSnO3 kept the cubic lattice, the Raman\nspectra suggested a dynamic distortion at low temperature. The density\nfunctional theory was applied to analyze the electronic structures and phonon\ndispersions of Ba1-xSrxSnO3(x = 0, 0.0125), and the behaviors of electron bands\naround Fermi levels were discussed. According to the experimental and\ntheoretical results, the Sr-doping played a significant role in tuning the\nindirect band gap of BaSnO3 and influenced the electron-phonon interaction."
    },
    {
        "anchor": "Room-temperature ferromagnetism at an oxide/nitride interface: Heterointerfaces have led to the discovery of novel electronic and magnetic\nstates because of their strongly entangled electronic degrees of freedom.\nSingle-phase chromium compounds always exhibit antiferromagnetism following the\nprediction of Goodenough-Kanamori rules. So far, exchange coupling between\nchromium ions via hetero-anions has not been explored and the associated\nquantum states is unknown. Here we report the successful epitaxial synthesis\nand characterizations of chromium oxide (Cr2O3)-chromium nitride (CrN)\nsuperlattices. Room-temperature ferromagnetic spin ordering is achieved at the\ninterfaces between these two antiferromagnets, and the magnitude of the effect\ndecays with increasing layer thickness. First-principles calculations indicate\nthat robust ferromagnetic spin interaction between Cr3+ ions via\nanion-hybridizations across the interface yields the lowest total energy. This\nwork opens the door to fundamental understanding of the unexpected and\nexceptional properties of oxide-nitride interfaces and provides access to\nhidden phases at low-dimensional quantum heterostructures.",
        "positive": "Development of Ferroelectric Order in Relaxor (1-x)Pb(Mg1/3Nb2/3)O3 -\n  xPbTiO3: The microstructure and phase transition in relaxor ferroelectric\nPb(Mg1/3Nb2/3)O3 (PMN) and its solid solution with PbTiO3 (PT), PMN-xPT, remain\nto be one of the most puzzling issues of solid state science. In the present\nwork we have investigated the evolution of the phase symmetry in PMN-xPT\nceramics as a function of temperature (20 K < T < 500 K) and composition (0 <=\nx <= 0.15) by means of high-resolution synchrotron x-ray diffraction.\nStructural analysis based on the experimental data reveals that the\nsubstitution of Ti^4+ for the complex B-site (Mg1/3Nb2/3)^4+ ions results in\nthe development of a clean rhombohedral phase at a PT-concentration as low as\n5%. The results provide some new insight into the development of the\nferroelectric order in PMN-PT, which has been discussed in light of the\nkinetics of polar nanoregions and the physical models of the relaxor\nferroelectrics to illustrate the structural evolution from a relaxor to a\nferroelectric state."
    },
    {
        "anchor": "Effect of spin-orbit coupling on the high harmonics from the topological\n  Dirac semimetal Na3Bi: In this work, we performed extensive first-principles simulations of\nhigh-harmonic generation in the topological Diract semimetal Na3Bi using a\ntime-dependent density functional theory framework, focusing on the effect of\nspin-orbit coupling (SOC) on the harmonic response. We also derived a general\nanalytical model describing the microscopic mechanism of strong-field dynamics\nin presence of spin-orbit coupling, starting from a locally U(1)xSU(2)\ngauge-invariant Hamiltonian. Our results reveal that SOC: (i) affects the\nstrong-field ionization by modifying the bandstructure of Na3Bi, (ii) modifies\nthe electron velocity, making each spin channel to react differently to the\npump laser field, (iii) changes the emission timing of the emitted harmonics.\nMoreover, we show that the SOC affects the harmonic emission by directly\ncoupling the charge current to the spin currents, paving the way to the\nhigh-harmonic spectroscopy of spin currents in solids.",
        "positive": "Hydrogen-doped cubic diamond and the crystal structure of n-diamond: To understand the crystal structure of n-diamond, a hydrogen-doped (H-doped)\ndiamond model has been investigated using first principles calculations. In\nparticular, hydrogen concentration dependent elastic constants and lattice\nparameters for the H-doped diamond have been analyzed. Our results indicate\nthat when the hydrogen concentration is less than 19 at.%, the H-doped diamond\nis mechanically stable. When the hydrogen concentration is about 4 at.%, the\noptimized lattice parameter, simulated XRD pattern and electronic properties\nfor the H-doped diamond all agree well with the corresponding experimental\nvalues of n-diamond. The results imply that the n-diamond is likely to be an\nH-doped diamond."
    },
    {
        "anchor": "Enhancement of DFT-calculations at Petascale: Nuclear Magnetic\n  Resonance, Hybrid Density Functional Theory and Car-Parrinello calculations: One of the most promising techniques used for studying the electronic\nproperties of materials is based on Density Functional Theory (DFT) approach\nand its extensions.\n  DFT has been widely applied in traditional solid state physics problems where\nperiodicity and symmetry play a crucial role in reducing the computational\nworkload. With growing compute power capability and the development of improved\nDFT methods, the range of potential applications is now including other\nscientific areas such as Chemistry and Biology. However, cross disciplinary\ncombinations of traditional Solid-State Physics, Chemistry and Biology\ndrastically improve the system complexity while reducing the degree of\nperiodicity and symmetry. Large simulation cells containing of hundreds or even\nthousands of atoms are needed to model these kind of physical systems. The\ntreatment of those systems still remains a computational challenge even with\nmodern supercomputers. In this paper we describe our work to improve the\nscalability of Quantum ESPRESSO \\cite{Quantum-Espresso} for treating very large\ncells and huge numbers of electrons. To this end we have introduced an extra\nlevel of parallelism, over \\emph{\\emph{electronic bands}}, in three kernels for\nsolving computationally expensive problems: the Sternheimer equation solver\n(Nuclear Magnetic Resonance, package QE-GIPAW), the Fock operator builder\n(electronic ground-state, package PWscf) and most of the Car-Parrinello\nroutines (Car-Parrinello dynamics, package CP). Final benchmarks show our\nsuccess in computing the Nuclear Magnetic Response (NMR) chemical shift of a\nlarge biological assembly, the electronic structure of defected amorphous\nsilica with hybrid exchange-correlation functionals and the equilibrium atomic\nstructure of height Porphyrins anchored to a Carbon Nanotube, on many thousands\nof CPU cores.",
        "positive": "Comment on: \"Ferroelectricity in spiral magnets\": There is much interest in the physics of materials that show a strong\ncoupling between magnetic and electric degrees of freedom. In a recent paper by\nMostovoy a theory is presented that is based on symmetry arguments and leads to\nquite general claims which we feel merit some further analysis. In particular,\nMostovoy concludes that \"spiral magnets are, in general, ferroelectric\". We\nargue that this conclusion is not generally valid, and that the symmetry of the\nunit cell has to be taken into account by any symmetry-based magneto-electric\ncoupling theory. In an attempt to avoid further confusion in the search of new\nmultiferroic materials, we identify in this Comment some of the necessary\nsymmetry properties of spiral magnets that can lead to ferroelectricity."
    },
    {
        "anchor": "Negative Temperature in Spin Dynamics Simulations: A simple and computationally efficient algorithm enables implementing\nnegative temperature values in a spin dynamics simulation. The algorithm uses a\nLangevin spin dynamics thermostat with a negative damping parameter, enabling\nthe thermalization of an arbitrary interacting spin system to the Gibbs energy\ndistribution with a given negative temperature value. Canonical spin dynamics\nsimulations at a negative temperature are as robust as conventional positive\nspin temperature simulations, providing a tool for quantitative dynamic studies\nof the physics of highly excited magnetic states. Two simulation case studies\ndescribing spin systems with antiferromagnetic and ferromagnetic ground states\nare explored. The phase transitions occurring in the negative temperature range\ndo not necessarily exhibit similarities with their positive temperature\ncounterparts. The transition temperatures and the character of spin alignment\nvary depending on the spatial range and strength of spin-spin interactions.",
        "positive": "Time resolved measurements of the switching trajectory of Pt/Co elements\n  induced by spin-orbit torques: We report the experimental observation of spin-orbit torque induced switching\nof perpendicularly magnetized Pt/Co elements in a time resolved stroboscopic\nexperiment based on high resolution Kerr microscopy. Magnetization dynamics is\ninduced by injecting sub-nanosecond current pulses into the bilayer while\nsimultaneously applying static in-plane magnetic bias fields. Highly\nreproducible homogeneous switching on time scales of several tens of\nnanoseconds is observed. Our findings can be corroborated using micromagnetic\nmodelling only when including a field-like torque term as well as the\nDzyaloshinskii-Moriya interaction mediated by finite temperature."
    },
    {
        "anchor": "Hydrogen Compounds of Group-IV Nanosheets: The structural and electronic properties of the hydrides of silicene and\ngermanene have been studied using ab initio calculations. The trend for the M-H\n(M=C, Si, Ge) bond lengths, and corresponding bond energies, is consistent with\nthe atomic size trend, and comparable to those of MH_4 hydrides. Band\nstructures were also obtained for the buckled configuration, which is the\nstable form for both silicene and germanene. Upon hydrogenation, both silicane\n(indirect gap) and germanane (direct gap) are semiconducting.",
        "positive": "Carbon Nanomaterials to Combat Virus: A perspective in view of COVID-19: The rapid outbreaks of lethal viruses necessitate the development of novel\nantiviral substance. Besides the conventional antiviral substances,\nbiocompatible nanomaterials also have significant potential in combating the\nvirus at various stages of infection. Carbon nanomaterials have an impressive\nrecord against viruses and can deal with many crucial healthcare issues. In\naccordance with the published literature, biocompatible carbon nanomaterials\nhave a promising prospect as an antiviral substance. Subsequently, the\nantiviral properties of different carbon nanomaterials namely fullerene, carbon\nnanotube, carbon dot and graphene oxide have been reviewed."
    },
    {
        "anchor": "Random-Field Ising Models of Hysteresis: This is a review article of our work on hysteresis, avalanches, and\ncriticality. We provide an extensive introduction to scaling and\nrenormalization--group ideas, and discuss analytical and numerical results for\nsize distributions, correlation functions, magnetization, avalanche durations\nand average avalanche shapes, and power spectra. We focus here on applications\nto magnetic Barkhausen noise.",
        "positive": "Electronic Properties of Lithiated SnO-based Anode Materials: In this paper we use an ab-initio quantum transport approach to study the\nelectron current flowing through lithiated SnO anodes for potential\napplications in Li-ion batteries. By investigating a set of lithiated\nstructures with varying lithium concentrations, it is revealed that LixSnO can\nbe a good conductor, with values comparable to bulk $\\beta$-Sn and Li. A deeper\ninsight into the current distribution indicates that electrons preferably\nfollow specific trajectories, which offer superior conducting properties than\nothers. These channels have been identified and it is shown here how they can\nenhance or deteriorate the current flow in lithiated anode materials."
    },
    {
        "anchor": "Real Space Green's Function Approach to RIXS: We present an ab initio theory of core- and valence resonant inelastic x-ray\nscattering (RIXS) based on a real-space multiple scattering Green's function\nformalism and a quasi-boson model Hamiltonian. Simplifying assumptions are made\nwhich lead to an approximation of the RIXS spectrum in terms of a convolution\nof an effective x-ray absorption signal with the x-ray emission signal.\nAdditional many body corrections are incorporated in terms of an effective\nenergy dependent spectral function. Example calculations of RIXS are found to\ngive qualitative agreement with experimental data. Our approach also yields\nsimulations of lifetime-broadening suppressed XAS, as observed in high energy\nresolutionfluorescence detection experiment (HERFD). Finally possible\nimprovements to our approach are briefly discussed.",
        "positive": "Monolayer fullerene networks as photocatalysts for overall water\n  splitting: Photocatalytic water splitting can produce hydrogen in an environmentally\nfriendly way and provide alternative energy sources to reduce global carbon\nemissions. Recently, monolayer fullerene networks have been successfully\nsynthesized [Hou $\\textit{et al., Nature}$ $\\textbf{2022}$, 606, 507], offering\nnew material candidates for photocatalysis because of their large surface area\nwith abundant active sites, feasibility to be combined with other 2D materials\nto form heterojunctions, and the C$_{60}$ cages for potential hydrogen storage.\nHowever, efficient photocatalysts need a combination of a suitable band gap and\nappropriate positions of the band edges with sufficient driving force for water\nsplitting. In this study, I employ semilocal density functional theory and\nhybrid functional calculations to investigate the electronic structures of\nmonolayer fullerene networks. I find that only the weakly screened hybrid\nfunctional, in combine with time-dependent Hartree-Fock calculations to include\nthe exciton binding energy, can reproduce the experimentally obtained optical\nband gap of monolayer C$_{60}$. All the phases of monolayer fullerene networks\nhave suitable band gaps with high carrier mobility and appropriate band edges\nto thermodynamically drive overall water splitting. In addition, the optical\nproperties of monolayer C$_{60}$ are studied, and different phases of fullerene\nnetworks exhibit distinct absorption and recombination behavior, providing\nunique advantages either as an electron acceptor or as an electron donor in\nphotocatalysis."
    },
    {
        "anchor": "Annealing Relaxation of Ultrasmall Gold Nanostructures: Except serving as an excellent gift on proper occasions, gold finds\napplications in life sciences, particularly in diagnostics and therapeutics.\nThese applications were made possible by gold nanoparticles, which differ\ndrastically from macroscopic gold. Versatile surface chemistry of gold\nnanoparticles allows coating with small molecules, polymers, biological\nrecognition molecules. Theoretical investigation of nanoscale gold is not\ntrivial, because of numerous metastable states in these systems. Unlike\nelsewhere, this work obtains equilibrium structures using annealing simulations\nwithin the recently introduced PM7-MD method. Geometries of the ultrasmall gold\nnanostructures with chalcogen coverage are described at finite temperature, for\nthe first time.",
        "positive": "Creation of moir\u00e9 bands in a monolayer semiconductor by spatially\n  periodic dielectric screening: Moir\\'e superlattices of two-dimensional van der Waals materials have emerged\nas a powerful platform for designing electronic band structures and discovering\nemergent physical phenomena. A key concept involves the creation of\nlong-wavelength periodic potential and moir\\'e bands in a crystal through\ninterlayer hybridization when two materials are overlaid. Here we demonstrate a\nnew approach based on spatially periodic dielectric screening to create moir\\'e\nbands in a monolayer semiconductor. It relies on reduced dielectric screening\nof the Coulomb interactions in monolayer semiconductors and their environmental\ndielectric-dependent electronic band structure. We observe optical transitions\nbetween moir\\'e bands in monolayer WSe$_{2}$ when it is placed close to small\nangle-misaligned graphene on hexagonal boron nitride. The moir\\'e bands are a\nresult of long-range Coulomb interactions, strongly gate-tunable, and can have\nversatile superlattice symmetries independent of the crystal lattice of the\nhost material. Our result also demonstrates that monolayer semiconductors are\nsensitive local dielectric sensors."
    },
    {
        "anchor": "Anisotropic Vapor HF etching of silicon dioxide for Si microstructure\n  release: Damages are created in a sacrificial layer of silicon dioxide by ion\nimplantation to enhance the etch rate of silicon-dioxide in liquid and vapor\nphase hydrofluoric acid. The etch rate ratio between implanted and unimplanted\nsilicon dioxide is more than 150 in vapor hydrofluoric acid (VHF). This feature\nis of interest to greatly reduce the underetch of microelectromechanical\nsystems anchors. Based on the experimentally extracted etch rate of unimplanted\nand implanted silicon dioxide, the patterning of the sacrificial layer can be\npredicted by simulation.",
        "positive": "In-situ spectroscopy of intrinsic Bi2Te3 topological insulator thin\n  films and impact of extrinsic defects: Combined in-situ x-ray photoemission spectroscopy, scanning tunnelling\nspectroscopy and angle resolved photoemission spectroscopy of molecular beam\nepitaxy grown Bi2Te3 on lattice mismatched substrates reveal high quality\nstoichiometric thin films with topological surface states without a\ncontribution from the bulk bands at the Fermi energy. The absence of bulk\nstates at the Fermi energy is achieved without counter doping. We observe that\nthe surface morphology and electronic band structure of Bi2Te3 are not affected\nby in-vacuo storage and exposure to oxygen, whereas major changes are observed\nwhen exposed to ambient conditions. These films help define a pathway towards\nintrinsic topological devices."
    },
    {
        "anchor": "High energy collision cascades in tungsten: dislocation loops structure\n  and clustering scaling laws: Recent experiments on in-situ high-energy self-ion irradiation of tungsten\n(W) show the occurrence of unusual cascade damage effects resulting from single\nion impacts, shedding light on the nature of radiation damage expected in the\ntungsten components of a fusion reactor. In this paper, we investigate the\ndynamics of defect production in 150 keV collision cascades in W at atomic\nresolution, using molecular dynamics simulations and comparing predictions with\nexperimental observations. We show that cascades in W exhibit no subcascade\nbreak-up even at high energies, producing a massive, unbroken molten area,\nwhich facilitates the formation of large defect clusters. Simulations show\nevidence of the formation of both 1/2<111> and <100> interstitial-type\ndislocation loops, as well as the occurrence of cascade collapse resulting in\n<100> vacancy-type dislocation loops, in excellent agreement with experimental\nobservations. The fractal nature of the cascades gives rise to a scale-less\npower law type size distribution of defect clusters.",
        "positive": "New density functional approach for solid-liquid-vapor transitions in\n  pure materials: A new phase field crystal (PFC) type theory is presented, which accounts for\nthe full spectrum of solid-liquid-vapor phase transitions within the framework\nof a single density order parameter. Its equilibrium properties show the most\nquantitative features to date in PFC modelling of pure substances, and full\nconsistency with thermodynamics in pressure-volume-temperature space is\ndemonstrated. A method to control either the volume or the pressure of the\nsystem is also introduced. Non-equilibrium simulations show that 2 and 3-phase\ngrowth of solid, vapor and liquid can be achieved, while our formalism also\nallows for a full range of pressure-induced transformations. This model opens\nup a new window for the study of pressure driven interactions of condensed\nphases with vapor, an experimentally relevant paradigm previously missing from\nphase field crystal theories."
    },
    {
        "anchor": "Study of soft/hard bimagnetic CoFe2/CoFe2O4 nanocomposite: We report an experimental study of the bimagnetic nanocomposites\nCoFe2/CoFe2O4.The precursor material, CoFe2O4 was prepared using the\nconventional stoichiometric combustion method. The nanocomposite CoFe2/CoFe2O4\nwas obtained by total reduction of CoFe2O4 using a thermal treatment at 350oC\nin H2 atmospheres following a partial oxidation in O2 atmospheres at 380oC\nduring 120; 30; 15, 10, and 5 min. The X-ray diffraction and Mossbauer\nspectroscopy confirmed the formation the material CoFe2/CoFe2O4 The magnetic\nhysteresis with different saturation magnetization confirms the formation of\nthe CoFe2/CoFe2O4 with different content of CoFe2O4. The high energy milling to\nthe precursor material increase the coercivity from 1.0 to 3.3 kOe, however the\nsame effect was not observed to the CoFe2/CoFe2O4 material.",
        "positive": "Size-dependent Surface States on Strained Cobalt Nanoislands on Cu(111): Low-temperature scanning tunneling spectroscopy over Co nanoislands on\nCu(111) showed that the surface states of the islands vary with their size.\nOccupied states exhibit a sizeable downward energy shift as the island size\ndecreases. The position of the occupied states also significantly changes\nacross the islands. Atomic-scale simulations and ab inito calculations\ndemonstrate that the driving force for the observed shift is related to\nsize-dependent mesoscopic relaxations in the nanoislands."
    },
    {
        "anchor": "Signatures of nonlinear magnetoelectricity in second harmonic spectra of\n  SU(2) symmetry broken quantum many-body systems: Quantum mechanical perturbative expressions for second order dynamical\nmagnetoelectric (ME) susceptibilities have been derived and calculated for a\nsmall molecular system using the Hubbard Hamiltonian with SU(2) symmetry\nbreaking in the form of spin-orbit coupling (SOC) or spin-phonon coupling.\nThese susceptibilities will have signatures in second harmonic generation\nspectra. We show that SU(2) symmetry breaking is the key to generate these\nsusceptibilities. We have calculated these ME coefficients by solving the\nHamiltonian for low lying excited states using Lanczos method. Varying the\nHubbard term along with SOC strength, we find spin and charge and both\nspin-charge dominated spectra of dynamical ME coefficients. We have shown that\nintensities of the peaks in the spectra are highest when the magnitudes of\nHubbard term and SOC coupling term are in similar range.",
        "positive": "Van der Waals Spin-Orbit Torque Antiferromagnetic Memory: The technique of conventional ferromagnet/heavy-metal spin-orbit torque (SOT)\noffers significant potential for enhancing the efficiency of magnetic memories.\nHowever, it faces fundamental physical limitations, including hunting effects\nfrom the metallic layer, broken symmetry for enabling antidamping switching,\nspin scattering caused by interfacial defects, and sensitivity to stray\nmagnetic fields. To address these issues, we here propose a van der Waals (vdW)\nfield-free SOT antiferromagnetic memory using a vdW bilayer LaBr$_2$ (an\nantiferromagnet with perpendicular magnetic anisotropy) and a monolayer T$_d$\nphase WTe$_2$ (a Weyl semimetal with broken inversion symmetry). By\nsystematically employing density functional theory in conjunction with\nnon-equilibrium Green's function methods and macrospin simulations, we\ndemonstrate that the proposed vdW SOT devices exhibit remarkably low critical\ncurrent density approximately 10 MA/cm$^2$ and rapid field-free magnetization\nswitching in 250 ps. This facilitates excellent write performance with\nextremely low energy consumption. Furthermore, the device shows a significantly\nlow read error rate, as evidenced by a high tunnel magnetoresistance ratio of\nup to 4250%. The superior write and read performance originates from the unique\nstrong on-site (insulating phase) and off-site (magnetic phase) Coulomb\ninteractions in electride LaBr$_2$, a large non-zero z-component polarization\nin WTe$_2$, and the proximity effect between them."
    },
    {
        "anchor": "Design of a Mott Multiferroic from a Non-Magnetic Polar Metal: We examine the electronic properties of newly discovered \"ferroelectric\"\nmetal LiOsO$_3$ combining density-functional and dynamical mean-field theories.\nWe show that the material is close to a Mott transition and that electronic\ncorrelations can be tuned to engineer a Mott multiferroic state in 1/1\nsuperlattice of LiOsO$_3$ and LiNbO$_3$. We use electronic structure\ncalculations to predict that the (LiOsO$_3$)$_1$/(LiNbO$_3$)$_1$ superlattice\nis a type-I multiferroic material with a ferrolectric polarization of\n41.2~$\\mu$C cm$^{-2}$, Curie temperature of 927\\,K, and N\\'eel temperature of\n671\\,K. Our results support a route towards high-temperature multiferroics,\n\\emph{i.e.}, driving non-magnetic \\emph{polar metals} into correlated\ninsulating magnetic states.",
        "positive": "Prediction of Van Hove singularity systems in ternary borides: A computational search for stable structures among both $\\alpha$ and $\\beta$\nphases of ternary ATB4 borides (A= Mg, Ca, Sr, Ba, Al, Ga, and Zn, T is 3d or\n4d transition elements) has been performed. We found that $\\alpha$-ATB4\ncompounds with A=Mg, Ca, Al, and T=V, Cr, Mn, Fe, Ni, and Co form a family of\nstructurally stable or almost stable materials. These systems are metallic in\nnon-magnetic states and characterized by the formation of the localized\nmolecular-like state of 3d transition metal atom dimers, which leads to the\nappearance of numerous Van Hove singularities (VHS) in the electronic spectrum.\nThe closeness of these VHS to the Fermi level can be easily tuned by electron\ndoping. For the atoms in the middle of the 3d row (Cr, Mn, and Fe), these VHS\nled to magnetic instabilities and new magnetic ground states with a weakly\nmetallic or semiconducting nature. The magnetic ground states in these systems\nappear as an analog of the spin glass state. Experimental attempts to produce\nMgFeB4 and associated challenges are discussed, and promising directions for\nfurther synthetic studies are formulated."
    },
    {
        "anchor": "First-principles study of ferroelectricity induced by p-d hybridization\n  in ferrimagnetic NiFe2O4: We investigate the ferrimagnetism and ferroelectricity of bulk NiFe$_2$O$_4$\nwith tetragonal $P4_122$ ~symmetry by means of density functional calculations\nusing generalized gradient approximation + Hubbard $U$ approach. Special\nattention is paid to finding the most energetically favorable configuration on\nmagnetic ordering and further calculating the reliable spontaneous electric\npolarization. With the fully optimized crystalline structure of the most stable\nconfiguration, the spontaneous polarization is obtained to be 23 $\\mu$C/cm$^2$\nalong the z direction, which originates from the hybridization between the 3d\nstates of the Fe$^{3+}$ cation and the 2p states of oxygen induced by\nJahn-Teller effect.",
        "positive": "Surface recombination and out of plane diffusivity of free excitons in\n  hexagonal boron nitride: We present a novel experimental protocol using Cathodoluminescence\nmeasurements as a function of the electron incident energy to study both\nexciton diffusion in a directional way and surface exciton recombination. Our\napproach overcomes the challenges of anisotropic diffusion and the limited\napplicability of existing methods to the bulk counterparts of 2D materials. The\nprotocol is then applied at room and at cryogenic temperatures to four bulk\nhexagonal boron nitride crystals grown by different synthesis routes. The\nexciton diffusivity depends on the sample quality but not on the temperature,\nindicating it is limited by defect scattering even in the best quality\ncrystals. The lower limit for the diffusivity by phonon scattering is 0.2\ncm$^{2}$.s$^{-1}$. Diffusion lengths were as much as 570 nm. Finally, the\nsurface recombination velocity exceeds 10$^{5}$ cm$^{2}$.s$^{-1}$, at a level\nsimilar to silicon or diamond. This result reveals that surface recombination\ncould strongly limit light-emitting devices based on 2D materials."
    },
    {
        "anchor": "Study of strain effect on in-plane polarization in epitaxial BiFeO3 thin\n  films using planar electrodes: Epitaxial strain plays an important role in determining physical properties\nof perovskite ferroelectric oxide thin films. However, it is very challenging\nto directly measure properties such as polarization in ultrathin strained films\nusing traditional sandwich capacitor devices, because of high leakage current.\nWe employed a planar electrode device with different crystallographical\norientations between electrodes along different electric field orientation to\ndirectly measure the in-plane polarization-electric field (P-E) hysteresis\nloops in fully strained thin films. At high misfit strains such as -4.4%, the\npure Tetrogonal-like phase is obtained and its polarization vector is\nconstrained to lie in the (010) plane with a significantly large in-plane\ncomponent, ~44 {\\mu}C/cm2. First-principle calculations are carried out in\nparallel, and provide a good agreement with the experimental results. Our\nresults pave the way to design in-plane devices based on T-like BFO and the\nstrategy proposed here can be expanded to study all other similar strained\nmultiferroic ultrathin films.",
        "positive": "Unexpectedly high salt accumulation inside carbon nanotubes soaked in\n  very dilute salt solutions: We experimentally demonstrate the formation of salt aggregations with\nunexpectedly high concentration inside multi-walled carbon nanotubes (CNTs)\nsoaked only in dilute salt solutions and even in solutions containing only\ntraces of salts. This finding suggests the blocking of fluid across CNTs by the\nsalt aggregations when CNTs are soaked in a dilute salt solution with the\nconcentration of seawater or even lower, which may open new avenues for the\ndevelopment of novel CNT-based desalination techniques. The high salt\naccumulation of CNTs also provides a new CNT-based strategy for the\ncollection/extraction of noble metal salts in solutions containing traces of\nnoble metal salts. Theoretical analyses reveal that this high salt accumulation\ninside CNTs can be mainly attributed to the strong hydrated cation-pi\ninteractions of hydrated cations and pi electrons in the aromatic rings of\nCNTs."
    },
    {
        "anchor": "Silicon spin chains at finite temperature: dynamics of Si(553)-Au: When gold is deposited on Si(553), the surface self-assembles to form a\nperiodic array of steps with nearly perfect structural order. In scanning\ntunneling microscopy these steps resemble quasi-one-dimensional atomic chains.\nAt temperatures below ~50 K the chains develop tripled periodicity. We recently\npredicted, on the basis of density-functional theory calculations at T=0, that\nthis tripled periodicity arises from the complete polarization of the electron\nspin on every third silicon atom along the step; in the ground state these\nlinear chains of silicon spins are antiferromagnetically ordered. Here we\nexplore, using ab-initio molecular dynamics and kinetic Monte Carlo\nsimulations, the behavior of silicon spin chains on Si(553)-Au at finite\ntemperature. Thermodynamic phase transitions at T>0 in one-dimensional systems\nare prohibited by the Mermin-Wagner theorem. Nevertheless we find that a\nsurprisingly sharp onset occurs upon cooling---at about 30 K for perfect\nsurfaces and at higher temperature for surfaces with defects---to a\nwell-ordered phase with tripled periodicity, in good agreement with experiment.",
        "positive": "Quantized Conductance of a Single Magnetic Atom: A single Co atom adsorbed on Cu(111) or on ferromagnetic Co islands is\ncontacted with non-magnetic W or ferromagnetic Ni tips in a scanning tunneling\nmicroscope. When the Co atom bridges two non-magnetic electrodes conductances\nof 2e^2/h are found. With two ferromagnetic electrodes a conductance of e^2/h\nis observed which may indicate fully spin-polarized transport."
    },
    {
        "anchor": "Oscillatory Instability in Two-Dimensional Dynamic Fracture: The stability of a rapid dynamic crack in a two dimensional infinite strip is\nstudied in the framework of Linear Elasticity Fracture Mechanics supplemented\nwith a modified principle of local symmetry. It is predicted that a single\ncrack becomes unstable by a finite wavelength oscillatory mode at a velocity\n$v_c$, $0.8c_R<v_c<0.85c_R$, where $c_R$ is the Rayleigh wave speed. The\nrelevance of this theoretical calculation to the oscillatory instability\nreported in the companion experimental Letter is discussed.",
        "positive": "Evidence of topological insulator state in the semimetal LaBi: By employing angle-resolved photoemission spectroscopy combined with\nfirst-principles calculations, we performed a systematic investigation on the\nelectronic structure of LaBi, which exhibits extremely large magnetoresistance\n(XMR), and is theoretically predicted to possess band anticrossing with\nnontrivial topological properties. Here, the observations of the Fermi-surface\ntopology and band dispersions are similar to previous studies on LaSb [Phys.\nRev. Lett. 117, 127204 (2016)], a topologically trivial XMR semimetal, except\nthe existence of a band inversion along the $\\Gamma$-$X$ direction, with one\nmassless and one gapped Dirac-like surface state at the $X$ and $\\Gamma$\npoints, respectively. The odd number of massless Dirac cones suggests that LaBi\nis analogous to the time-reversal $Z_2$ nontrivial topological insulator. These\nfindings open up a new series for exploring novel topological states and\ninvestigating their evolution from the perspective of topological phase\ntransition within the family of rare-earth monopnictides."
    },
    {
        "anchor": "Theoretical limit of the minimal magnetization switching field and the\n  optimal field pulse for Stoner particles: The theoretical limit of the minimal magnetization switching field and the\noptimal field pulse design for uniaxial Stoner particles are investigated. Two\nresults are obtained. One is the existence of a theoretical limit of the\nsmallest magnetic field out of all possible designs. It is shown that the limit\nis proportional to the damping constant in the weak damping regime and\napproaches the Stoner-Wohlfarth (SW) limit at large damping. For a realistic\ndamping constant, this limit is more than ten times smaller than that of\nso-called precessional magnetization reversal under a non-collinear static\nfield. The other is on the optimal field pulse design: If the magnitude of a\nmagnetic field does not change, but its direction can vary during a reversal\nprocess, there is an optimal design that gives the shortest switching time. The\nswitching time depends on the field magnitude, damping constant, and magnetic\nanisotropy. However, the optimal pulse shape depends only on the damping\nconstant.",
        "positive": "Pressure induced electride phase formation in calcium: A key to its\n  strange high-pressure behavior: Elemental calcium (Ca), a simple metal at ambient conditions, has attracted\nhuge interest because of its unusual high-pressure behavior in structural,\nelectrical, and melting properties whose origin remain unsolved. Here, using a\ntheoretical framework appropriate for describing electride phase formation,\ni.e., the presence of anionic electrons, we establish electride formation in Ca\nat a pressure as low as 8 GPa. Our analysis shows that under pressure the\nvalence electrons of Ca localize at octahedral holes and exhibit anionic\ncharacter which is responsible for its strange pressure behavior. Our\ncalculated enthalpy and electrical resistance indicate that Ca will directly\ntransform from an FCC-electride phase to an SC-electride phase near 30 GPa\nthereby avoiding the intermediate BCC phase. These findings are not limited to\nCa but might hold a key to the understanding of host-guest type structures\nwhich occur in other elemental solids though at much higher pressures."
    },
    {
        "anchor": "Amorphous alloys surpass E/10 strength limit at extreme strain rates: Theoretical predictions of the ideal strength of materials range from E/30 to\nE/10 (E is Young's modulus). However, despite intense interest over the last\ndecade, the value of the ideal strength that can be attained experimentally for\nmetals remains a mystery (1-5). In this study, we demonstrated the\nunprecedented strength of an amorphous Cu-Zr alloy that surpassed the E/10\nlimit. Laser-induced shock experiments were conducted on Cu50Zr50 to explore\nits strength and failure mechanisms at ultrahigh strain rates. The material\ndemonstrated a high spall strength of 9.8 GPa, approximately 1/13 of its P-wave\nmodulus (~ E/6), at strain rates greater than 10^7 s^-1, which sets a new\nrecord for the elastic limit of metallic materials. Electron microscopy and\nlarge-scale molecular dynamics simulations revealed that void nucleation and\ngrowth, not shear-banding, comprised the major failure mechanism for metallic\nglasses at extremely fast strain rates. A new model for void formation under\nthe control of surface energy explained the rate dependence of the material\nstrength. The results of this study reveal new possible ways to use the\namorphous phase in nanostructured metals in future applications under demanding\nmechanical conditions.",
        "positive": "A van der Waals density functional study of chloroform and bromoform on\n  graphene: A calculational study of the trihalomethanes chloroform (CHCl_3) and\nbromoform (CHBr_3) adsorbed on graphene is presented. The study uses the van\nder Waals density functional method vdW-DF to obtain adsorption energies and\nadsorption structures for these molecules of environmental concern. In this\nstudy chloroform is found to adsorb with the H atom pointing away from\ngraphene, with adsorption energy 357 meV (34.4 kJ/mol). For bromoform the\ncalculated adsorption energy is 404 meV (39.0 kJ/mol). The corrugation of\ngraphene as seen by chloroform is small, the difference in adsorption energy\nalong the graphene plane is less than 6 meV."
    },
    {
        "anchor": "Exploring Thermal Transport in Electrochemical Energy Storage Systems\n  Utilizing Two-Dimensional Materials: Prospects and Hurdles: Two-dimensional materials and their heterostructures have enormous\napplications in Electrochemical Energy Storage Systems (EESS) such as\nbatteries. A comprehensive and solid understanding of these materials' thermal\ntransport and mechanism is essential for the practical design of EESS.\nExperiments have challenges in providing improved control and characterization\nof complex structures, especially for low dimensional materials. Theoretical\nand simulation tools such as first-principles calculations, boltzmann transport\nequations, molecular dynamics simulations, lattice dynamics simulation, and\nnon-equilibrium Green's function provide reliable predictions of thermal\nconductivity and physical insights to understand the underlying thermal\ntransport mechanism in materials. However, doing these calculations require\nhigh computational resources. The development of new materials synthesis\ntechnology and fast-growing demand for rapid and accurate prediction of\nphysical properties require novel computational approaches. The machine\nlearning (ML) method provides a promising solution to address such needs. This\nreview details the recent development in atomistic/molecular studies and ML of\nthermal transport in EESS. The paper also addresses the latest significant\nexperimental advances. However, designing the best low-dimensional\nmaterials-based heterostructures is like a multivariate optimization problem.\nFor example, a particular heterostructure may be suitable for thermal transport\nbut can have lower mechanical strength/stability. For bi/multilayer structures,\nthe interlayer distance may influence the thermal transport properties and\ninterlayer strength. Therefore, the last part addresses the future research\ndirection in low-dimensional materials-based heterostructure design for thermal\ntransport in EESS.",
        "positive": "Nonequilibrium Thermodynamics of the Kovacs Effect: We present a thermodynamic theory of the Kovacs effect based on the idea that\nthe configurational degrees of freedom of a glass-forming material are driven\nout of equilibrium with the heat bath by irreversible thermal contraction and\nexpansion. We assume that the slowly varying configurational subsystem, i.e.\nthe part of the system that is described by inherent structures, is\ncharacterized by an effective temperature, and contains a volume-related\ninternal variable. We examine mechanisms by which irreversible dynamics of the\nfast, kinetic-vibrational degrees of freedom can cause the entropy and the\neffective temperature of the configurational subsystem to increase during\nsufficiently rapid changes in the bath temperature. We then use this theory to\ninterpret the numerical simulations by Mossa and Sciortino (MS), who observe\nthe Kovacs effect in more detail than is feasible in laboratory experiments.\nOur analysis highlights two mechanisms for the equilibration of internal\nvariables. In one of these, an internal variable first relaxes toward a state\nof quasi-equilibrium determined by the effective temperature, and then\napproaches true thermodynamic equilibrium as the effective temperature slowly\nrelaxes toward the bath temperature. In the other mechanism, an internal\nvariable directly equilibrates with the bath temperature on intermediate\ntimescales, without equilibrating with the effective temperature at any stage.\nBoth mechanisms appear to be essential for understanding the MS results."
    },
    {
        "anchor": "Oxygen-induced in-situ manipulation of the interlayer coupling and\n  exciton recombination in Bi2Se3/MoS2 2D heterostructures: 2D heterostructures are more than a sum of the parent 2D materials, but are\nalso a product of the interlayer coupling, which can induce new properties. In\nthis paper we present a method to tune the interlayer coupling in Bi2Se3/MoS2\n2D heterostructures by regulating the oxygen presence in the atmosphere, while\napplying laser or thermal energy. Our data suggests the interlayer coupling is\ntuned through the diffusive intercalation and de-intercalation of oxygen\nmolecules. When one layer of Bi2Se3 is grown on monolayer MoS2, an influential\ninterlayer coupling is formed that quenches the signature photoluminescence\n(PL) peaks. However, thermally annealing in the presence of oxygen disrupts the\ninterlayer coupling, facilitating the emergence of the MoS2 PL peak. DFT\ncalculations predict intercalated oxygen increases the interlayer separation\n~17%, disrupting the interlayer coupling and inducing the layers to behave more\nelectronically independent. The interlayer coupling can then be restored by\nthermally annealing in N2 or Ar, where the peaks will re-quench. Hence, this is\nan interesting oxygen-induced switching between \"non-radiative\" and \"radiative\"\nexciton recombination. This switching can also be accomplished locally,\ncontrollably, and reversibly using a low-power focused laser, while changing\nthe environment from pure N2 to air. This allows for the interlayer coupling to\nbe precisely manipulated with submicron spatial resolution, facilitating\nsite-programmable 2D light-emitting pixels whose emission intensity could be\nprecisely varied by a factor exceeding 200x. Our results show that these\natomically-thin 2D heterostructures may be excellent candidates for oxygen\nsensing.",
        "positive": "The electrical conductivity of cubic (In$_{1-x}$Ga$_x$)$_2$O$_3$ films\n  ($x\\le0.18$): Native point defects, Sn-doping, and the surface electron\n  accumulation layer: The alloying of the group-III transparent semiconducting sesquioxides\nIn$_2$O$_3$ and Ga$_2$O$_3$ can lead to a modulation of the properties of the\nparent compounds, e.g., the shallow- and deep-donor character of the oxygen\nvacancy or the presence and absence of a surface electron accumulation layer,\nrespectively. In this work, we investigate the effect of alloying on the\nelectron transport properties of unintentionally-doped single-crystalline and\ntextured bixbyite (In$_{1-x}$Ga$_x$)$_2$O$_3$ thin films annealed in oxygen and\nvacuum with Ga contents up to $x$=0.18. Hall effect measurements demonstrate a\nsurprising increase in electron density due to native defects with added Ga.\nThis increase may be related to the incorporation of Ga-interstitials or oxygen\nvacancies induced by Ga-related unit-cell distortions. A combined investigation\nbased on hard and soft x-ray photoelectron spectroscopy measurements\ndemonstrates the existence of the surface electron accumulation layer for all\nalloy films and, hence, no depletion up to $x$=0.18. Finally, we additionally\ndemonstrate a single-crystalline (In$_{0.92}$Ga$_{0.08}$)$_2$O$_3$:Sn film, as\na possible transparent conductive oxide with a wider band gap than that of\n(Sn-doped) In$_2$O$_3$."
    },
    {
        "anchor": "Magnetic susceptibility of alkali-TCNQ salts and extended Hubbard models\n  with bond order and charge density wave phases: The molar spin susceptibilities $\\chi(T)$ of Na-TCNQ, K-TCNQ and Rb-TCNQ(II)\nare fit quantitatively to 450 K in terms of half-filled bands of three\none-dimensional Hubbard models with extended interactions using exact results\nfor finite systems. All three models have bond order wave (BOW) and charge\ndensity wave (CDW) phases with boundary $V = V_c(U)$ for nearest-neighbor\ninteraction $V$ and on-site repulsion $U$. At high $T$, all three salts have\nregular stacks of $\\rm TCNQ^-$ anion radicals. The $\\chi(T)$ fits place Na and\nK in the CDW phase and Rb(II) in the BOW phase with $V \\approx V_c$. The Na and\nK salts have dimerized stacks at $T < T_d$ while Rb(II) has regular stacks at\n100K. The $\\chi(T)$ analysis extends to dimerized stacks and to dimerization\nfluctuations in Rb(II). The three models yield consistent values of $U$, $V$\nand transfer integrals $t$ for closely related $\\rm TCNQ^-$ stacks. Model\nparameters based on $\\chi(T)$ are smaller than those from optical data that in\nturn are considerably reduced by electronic polarization from quantum chemical\ncalculation of $U$, $V$ and $t$ on adjacent $\\rm TCNQ^-$ ions. The $\\chi(T)$\nanalysis shows that fully relaxed states have reduced model parameters compared\nto optical or vibration spectra of dimerized or regular $\\rm TCNQ^-$ stacks.",
        "positive": "Spin State of Single Molecular Magnet (SMM) Creating Long Range Ordering\n  on Ferromagnetic Layers of Magnetic Tunnel Junction -A Monte Carlo Study: Single molecular magnet (SMM) like paramagnetic molecules interacting with\nthe ferromagnetic electrodes of a magnetic tunnel junction (MTJ) produce a new\nsystem that differs dramatically from the properties of isolated molecules and\nferromagnets. However, it is unknown how far deep in the ferromagnetic\nelectrode the impact of the paramagnetic molecule and ferromagnet interactions\ncan travel for various levels of molecular spin states. Our prior experimental\nstudies showed two types of paramagnetic SMMs, the hexanuclear Mn6 and\noctanuclear Fe-Ni molecular complexes, covalently bonded to ferromagnets\nproduced unprecedented strong antiferromagnetic coupling between two\nferromagnets at room temperature leading to a number of intriguing\nobservations. In this paper, we report Monte Carlo Simulations (MCS) study\nfocusing on the impact of the molecular spin state on cross junction shaped MTJ\nbased molecular spintronics device (MTJMSD). Our MCS study focused on the\nHeisenberg model of MTJMSD and investigated the impact of various molecular\ncoupling strengths, thermal energy, and molecular spin states. To gauge the\nimpact of the molecular spin state on the region of ferromagnetic electrodes,\nwe examined the spatial distribution of molecule-ferromagnet correlated phases.\nOur MCS study shows that under a strong coupling regime molecular spin state\nshould be approximately 30 percent of the ferromagnetic electrode atomic spins\nto create long-range correlated phases."
    },
    {
        "anchor": "On the stability of \"non-magic\" endohedrally doped Si clusters: A\n  first-principles sampling study of MSi16^+ (M =Ti,V,Cr): Density-functional theory is used to study the geometric and electronic\nstructure of cationic Si16^+ clusters with a Ti, V or Cr dopant atom. Through\nunbiased global geometry optimization based on the basin-hopping approach we\nconfirm that a Frank- Kasper polyhedron with the metal atom at the center\nrepresents the ground-state isomer for all three systems. The endohedral cage\ngeometry is thus stabilized even though only VSi16^+ achieves electronic shell\nclosure within the prevalent spherical potential model. Our analysis of the\nelectronic structure traces this diminished role of shell closure for the\nstabilization back to the adaptive capability of the metal- Si bonding, which\nis more the result of a complex hybridization than the orginally proposed mere\nformal charge transfer. The resulting flexibility of the metal-Si bond can help\nto stabilize also \"non-magic\" cage-dopant combinations, which suggests that a\nwider range of materials may eventually be cast into this useful geometry for\ncluster-assembled materials.",
        "positive": "Dynamics of Lennard-Jones clusters: A characterization of the\n  activation-relaxation technique: The potential energy surface (PES) of Lennard-Jones clusters is investigated\nusing the activation-relaxation technique (ART). This method defines events in\nthe configurational energy landscape as a two-step process: (a) a configuration\nis first activated from a local minimum to a nearby saddle-point and (b) is\nthen relaxed to a new minimum. Although ART has been applied with success to a\nwide range of materials such as a-Si, a-SiO2 and binary Lennard-Jones glasses,\nquestions remain regarding the biases of the technique. We address some of\nthese questions in a detailed study of ART-generated events in Lennard-Jones\n(LJ) clusters, a system for which much is already known. In particular, we\nstudy the distribution of saddle-points, the pathways between configurations,\nand the reversibility of paths. We find that ART can identify all trajectories\nwith a first-order saddle point leaving a given minimum, is fully reversible,\nand samples events following the Boltzmann weight at the saddle point."
    },
    {
        "anchor": "Three photon absorption in ZnO and ZnS crystals: We report a systematic investigation of both three-photon absorption\n(3PA)spectra and wavelength dispersions of Kerr-type nonlinear refraction in\nwide-gap semiconductors. The Z-scan measurements are recorded for both ZnO and\nZnS with femtosecond laser pulses. While the wavelength dispersions of the Kerr\nnonlinearity are in agreement with a two-band model, the wavelength dependences\nof the 3PA are found to be given by (3Ephoton/Eg-1)5/2(3Ephoton/Eg)-9. We also\nevaluate higher-order nonlinear optical effects including the fifth-order\ninstantaneous nonlinear refraction associated with virtual three-photon\ntransitions, and effectively seventh-order nonlinear processes induced by\nthree-photon-excited free charge carriers. These higher-order nonlinear effects\nare insignificant with laser excitation irradiances up to 40 GW/cm2. Both\npump-probe measurements and three-photon figures of merits demonstrate that ZnO\nand ZnS should be a promising candidate for optical switching applications at\ntelecommunication wavelengths.",
        "positive": "Giant Anomalous Hall Effect due to Double-Degenerate Quasi Flat Bands: We propose a novel approach to achieve giant AHE in materials with flat bands\n(FBs). FBs are accompanied by small electronic bandwidths, which consequently\nincreases the momentum separation ($K$) within pair of Weyl points and thus the\nintegrated Berry curvature. Starting from a simple model with a single pair of\nWeyl nodes, we demonstrated the increase of $K$ and AHE by decreasing\nbandwidth. It is further expanded to a realistic pyrochlore lattice model with\ncharacteristic double degenerated FBs, where we discovered a giant AHE while\nmaximizing the $K$ with nearly vanishing band dispersion of FBs. We identify\nthat such model system can be realized in both pyrochlore and spinel compounds\nbased on first-principles calculations, validating our theoretical model and\nproviding a feasible platform for experimental exploration."
    },
    {
        "anchor": "A TEM study of Si-SiO2 interfaces in silicon nanodevices: The fabrication of micro- and nano-scale silicon electronic devices requires\nprecision lithography and controlled processing to ensure that the electronic\nproperties of the device are optimized. Importantly, the Si-SiO2 interface\nplays a crucial role in defining these properties. While transmission electron\nmicroscopy (TEM) can be used to observe the device architecture, substrate /\ncontact crystallinity and interfacial roughness, the preparation and isolation\nof the device active area is problematic. In this work, we describe the use of\nfocussed ion beam technologies to isolate and trench-cut targeted device\nstructures for subsequent TEM analysis. Architectures studied include radio\nfrequency, single electron transistors and electrically detected, magnetic\nresonance devices that have also undergone ion implantation, rapid thermal and\nforming gas anneals.",
        "positive": "Experimental observation of node-line-like surface states in LaBi: In a Dirac nodal line semimetal, the bulk conduction and valence bands touch\nat extended lines in the Brillouin zone. To date, most of the theoretically\npredicted and experimentally discovered nodal lines derive from the bulk bands\nof two- and three-dimensional materials. Here, based on combined angle-resolved\nphotoemission spectroscopy measurements and first-principles calculations, we\nreport the discovery of node-line-like surface states on the (001) surface of\nLaBi. These bands derive from the topological surface states of LaBi and bridge\nthe band gap opened by spin-orbit coupling and band inversion. Our\nfirst-principles calculations reveal that these \"nodal lines\" have a tiny gap,\nwhich is beyond typical experimental resolution. These results may provide\nimportant information to understand the extraordinary physical properties of\nLaBi, such as the extremely large magnetoresistance and resistivity plateau."
    },
    {
        "anchor": "Domain wall fluctuations in ferroelectrics coupled to strain: Using a Ginzburg--Landau--Devonshire model that includes the coupling of\npolarization to strain, we calculate the fluctuation spectra of ferroelectric\ndomain walls. The influence of the strain coupling differs between 180 degree\nand 90 degree walls due to the different strain profiles of the two\nconfigurations. The finite speed of acoustic phonons, $v_s$, retards the\nresponse of the strain to polarization fluctuations, and the results depend on\n$v_s$. For $v_s \\to \\infty$, the strain mediates an instantaneous\nelectrostrictive interaction, which is long-range in the 90 degree wall case.\nFor finite $v_s$, acoustic phonons damp the wall excitations, producing a\ncontinuum in the spectral function. As $v_s\\ to 0$, a gapped mode emerges,\nwhich corresponds to the polarization oscillating in a fixed strain potential.",
        "positive": "Non-uniform plastic deformations of crystals undergoing anti-plane\n  constrained shear: The present paper studies non-uniform plastic deformations of crystals\nundergoing anti-plane constrained shear. The asymptotically exact energy\ndensity of crystals containing a moderately large density of excess\ndislocations is found by the averaging procedure. This energy density is\nextrapolated to the cases of extremely small or large dislocation densities. By\nincorporating the configurational temperature and the density of redundant\ndislocations, we develop the thermodynamic dislocation theory for non-uniform\nplastic deformations and use it to predict the stress-strain curves and the\ndislocation densities."
    },
    {
        "anchor": "High-temperature ferromagnetism of $sp$ electrons in narrow impurity\n  bands: Application to CaB$_6$: Ferromagnetism with high Curie temperature $T_c$, well above room\ntemperature, and very small saturation moment has been reported in various\ncarbon and boron systems. It is argued that the magnetization must be very\ninhomogeneous with only a small fraction of the sample ferromagnetically\nordered. It is shown that a possible source of high $T_c$ within the\nferromagnetic regions is itinerant electrons occupying a narrow impurity band.\nCorrelation effects do not reduce the effective interaction which enters the\nStoner criterion in the same way as in a bulk band. It is also shown how, in\nthe impurity band case, spin wave excitations may not be effective in lowering\n$T_c$ below its value given by Stoner theory. These ideas are applied to\nCaB$_6$ and a thorough review of the experimental situation in this material is\ngiven. It is suggested that the intrinsic magnetism of the B$_2$ and O$_2$\ndimers might be exploited in suitable structures containing these elements.",
        "positive": "Anomalous transport properties in Nb/Bi1.95Sb0.05Se3 hybrid structure: We report the proximity induced anomalous transport behavior in a Nb\nBi1.95Sb0.05Se3 heterostructure. Mechanically Exfoliated single crystal of\nBi1.95Sb0.05Se3 topological insulator (TI) is partially covered with a 100 nm\nthick Niobium superconductor using DC magnetron sputtering by shadow masking\ntechnique. The magnetotransport (MR) measurements have been performed\nsimultaneously on the TI sample with and without Nb top layer in the\ntemperature,T, range of 3 to 8 K, and a magnetic field B up to 15 T. MR on TI\nregion shows Subnikov de Haas oscillation at fields greater than 5 T. Anomalous\nlinear change in resistance is observed in the field range of negative 4T to\npositive 4T at which Nb is superconducting. At 0 T field, the temperature\ndependence of resistance on the Nb covered region revealed a superconducting\ntransition (TC) at 8.2 K, whereas TI area showed similar TC with the absence of\nzero resistance states due to the additional resistance from superconductor\n(SC) TI interface. Interestingly below the TC the R vs T measured on TI showed\nan enhancement in resistance for positive field and prominent fall in\nresistance for negative field direction. This indicates the directional\ndependent scattering of the Cooper pairs on the surface of the TI due to the\nsuperposition of spin singlet and triplet states in the superconductor and TI\nrespectively."
    },
    {
        "anchor": "First-principles calculation of electronic polarization of III-V\n  nanotubes: A first-principles study of the electronic polarization of BN and AlN\nnanotubes and their graphitic sheets under an external electric field has been\nperformed. We found that the polarization per atom of zigzag nanotubes\nincreases with decreasing diameter while that of armchair nanotubes decreases.\nThe variation of the polarization is related to the exterior angle of the bonds\naround the B or Al atoms rather than that around the N atoms. The increase in\nthe polarization of the zigzag nanotubes with decreasing diameter is caused by\nthe large variation of the exterior angle when they are wrapped into the\ntubular form. On the other hand, the decrease in the bond length results in the\nweak polarization of thin armchair nanotubes.",
        "positive": "Magnetic properties of rare earth and transition metal based perovskite\n  type high entropy oxides: High entropy oxides (HEO) are a recently introduced class of oxide materials,\nwhich are characterized by a large number of elements (i.e. five or more)\nsharing one lattice site which crystallize in a single phase structure. One\ncomplex example of the rather young HEO family are the rare-earth transition\nmetal perovskite high entropy oxides. In this comprehensive study, we provide\nan overview over the magnetic properties of three perovskite type high entropy\noxides. The compounds have a rare-earth site which is occupied by five\ndifferent rare-earth elements, while the transition metal site is occupied by a\nsingle transition metal. In this way a comparison to the parent binary oxides,\nnamely the orthocobaltites, -chromites and -ferrites is possible. X-ray\nabsorption near edge spectroscopy (XANES), magnetometry and M\\\"ossbauer\nspectroscopy are employed to characterize these complex materials.\n  In general, we find surprising similarities to the magnetic properties of the\nbinary oxides, despite the chemical disorder on the rare-earth site. However\ndistinct differences and interesting magnetic properties are also observed such\nas noncollinearity, spin reorientation transitions as well as large coercive\nfields of up to 2\\,T at ambient temperature. Both the chemical disorder on the\nRE A-site, and the nature of the TM on the B-site play an important role in the\nphysical properties of these high entropy oxides."
    },
    {
        "anchor": "Transport regimes for exciton-polaritons in disordered microcavities: Light-matter coupling in a planar optical cavity substantially modifies the\ntransport regimes in the system in presence of a short range excitonic\ndisorder. Basing on Master equation for a resonantly coupled exciton-photon\nsystem, and treating disorder scattering in the Born-Markov approximation we\ndemonstrate the onset of ballistic and diffusive transport regimes in the\nlimits of weak and strong disorder respectively. We show that transport\nparameters governing the crossover between these two regimes strongly depend on\nthe parameters characterizing light-matter coupling, in particular Rabi energy\nand detuning between excitonic and photonic modes. The presented theory agrees\nwith recent experimental data on transport in disordered organic microcavities.",
        "positive": "Microstructural pattern formation during liquid metal dealloying:\n  Phase-field simulations and theoretical analyses: In recent years, liquid metal dealloying (LMD) has emerged as a promising\nmaterial processing method to generate micro and nano-scale bicontinuous or\nporous structures. Most previous studies focused on the experimental\ncharacterization of the dealloying process and on the properties of the\ndealloyed materials, leaving the theoretical study incomplete to fully\nunderstand the fundamental mechanisms of LMD. In this paper, we use theoretical\nmodels and phase-field simulations to clarify the kinetics and pattern\nformation during LMD. Our study starts from a theoretical analysis of the 1D\ndissolution of a binary precursor alloy, which reveals that the 1D dissolution\nprocess involves two regimes. In the first regime, due to the low solubility of\none of the elements in the melt, it accumulates at the solid-liquid interface,\nwhich reduces the dissolution kinetics. In the second regime, the interface\nkinetics reaches a stationary regime where both elements of the precursor alloy\ndissolve into the melt. Previous works revealed that in the early dealloying\nstage, the dealloying front is destabilized by an interfacial spinodal\ndecomposition, which triggers the formation of interconnected ligaments. We\nextend this line of work by proposing a linear stability analysis able to\npredict the initial length-scale of the ligaments formed in the initial stage\nof the dealloying. Combining this analysis with the 1D dissolution model\nproposed here enables us to better understand the initial conditions\n(composition of the precursor alloy and the melt) leading to a planar\ndissolution without interface destabilization. Finally, we report a strong\ninfluence of solid-state diffusion on dealloying that was overlooked in\nprevious studies. Although the solid-state diffusivity is four to five orders\nof magnitude smaller than in the liquid phase, it is found to affect both\ndissolution kinetics and ligament morphologies."
    },
    {
        "anchor": "Melting of crystalline solids: It is suggested that at the melting temperature the thermal phonon vibration\nis in self-resonance with the lattice vibration of the surface atomic/molecular\nlayer. This self resonance occurs at a well defined temperature and triggers\nthe detachment of the atomic/molecular sheet or platelets from the surface of\nthe crystal. Thermodynamic data of five substances is used to test this\nhypothesis. The calculated average phonon vibrational wavelengths are equal\nwith or harmonics of the d-spacing of the atomic/molecular sheets. The proposed\nmodel is able to explain all of the features of melting.",
        "positive": "Domains in Three-dimensional Ferroelectric Nanostructures: Theory and\n  Experiment: Ferroelectric random access memory cells (FeRAMs) have reached 450 x 400 nm\nproduction (0.18 micron^2) at Samsung with lead zirconate-titanate (PZT), 0.13\nmicron^2 at Matsushita with strontium bismuth tantalate (SBT), and comparable\nsizes at Fujitsu with BiFeO3. However, in order to increase storage density,\nthe industry roadmap requires by 2010 that such planar devices be replaced with\nthree-dimensional structures. Unfortunately, little is known yet about even\nsuch basic questions as the domain scaling of 3-d nanodevices, as opposed to\n2-d thin films. Here we report the experimental measurement of nano-domains in\nferroelectric nanocolumns, together with a theory of domain size in 3-d\nstructures which explains the observations."
    },
    {
        "anchor": "Ni-Sn intermetallics as efficient buffering matrix of Si anodes in\n  Li-ion batteries: For a successful integration of silicon in high-capacity anodes of Li-ion\nbatteries, its intrinsic capacity decay on cycling due to severe volume\nswelling should be minimized. In this work, Ni-Sn intermetallics are studied as\nbuffering matrix during reversible lithiation of Si-based anodes. Si/Ni-Sn\ncomposites have been synthetized by mechanical milling using C and Al as\nprocess control agents. Ni3Sn4, Ni3Sn2 intermetallics and their bi-phasic\nmixture were used as constituents of the buffering matrix. The structure,\ncomposition and morphology of the composites have been analyzed by X-ray\ndiffraction (XRD), 119Sn Transmission M\\\"ossbauer Spectroscopy (TMS) and\nscanning electron microscopy (SEM). They consist of ~ 150 nm Si nanoparticles\nembedded in a multi-phase matrix, the nanostructuration of which improves on\nincreasing the Ni3Sn4 amount. The electrochemical properties of the composites\nwere analyzed by galvanostatic cycling in half-cells. Best results for\npractical applications are found for the bi-phasic matrix Ni3Sn4-Ni3Sn2 in\nwhich Ni3Sn4 is electrochemically active while Ni3Sn2 is inactive. Low capacity\nloss, 0.04 %/cycle, and high coulombic efficiency, 99.6%, were obtained over\n200 cycles while maintaining a high reversible capacity above 500 mAh/g at\nmoderate regime C/5",
        "positive": "Two-dimensional ferroelectric tunnel junction: the case of monolayer\n  In:SnSe/SnSe/Sb:SnSe homostructure: Ferroelectric tunnel junctions, in which ferroelectric polarization and\nquantum tunneling are closely coupled to induce the tunneling electroresistance\n(TER) effect, have attracted considerable interest due to their potential in\nnon-volatile and low-power consumption memory devices. The ferroelectric size\neffect, however, has hindered ferroelectric tunnel junctions from exhibiting\nrobust TER effect. Here, our study proposes doping engineering in a\ntwo-dimensional in-plane ferroelectric semiconductor as an effective strategy\nto design a two-dimensional ferroelectric tunnel junction composed of\nhomostructural $p$-type semiconductor/ferroelectric/$n$-type semiconductor.\nSince the in-plane polarization persists in the monolayer ferroelectric\nbarrier, the vertical thickness of two-dimensional ferroelectric tunnel\njunction can be as thin as monolayer. We show that the monolayer\nIn:SnSe/SnSe/Sb:SnSe junction provides an embodiment of this strategy.\nCombining density functional theory calculations with non-equilibrium Green's\nfunction formalism, we investigate the electron transport properties of\nIn:SnSe/SnSe/Sb:SnSe and reveal a giant TER effect of 1460$\\%$. The dynamical\nmodulation of both barrier width and barrier height during the ferroelectric\nswitching are responsible for this giant TER effect. These findings provide an\nimportant insight towards the understanding of the quantum behaviors of\nelectrons in materials at the two-dimensional limit, and enable new\npossibilities for next-generation non-volatile memory devices based on flexible\ntwo-dimensional lateral ferroelectric tunnel junctions."
    },
    {
        "anchor": "Near-field spectra of quantum well excitons with non-Markovian phonon\n  scattering: The excitonic absorption spectrum for a disordered quantum well in presence\nof exciton-acoustic phonon interaction is treated beyond the Markov\napproximation. Realistic disorder exciton states are taken from a microscopic\nsimulation, and the deformation potential interaction is implemented. The\nexciton Green's function is solved with a self energy in second order Born\nquality. The calculated spectra differ from a superposition of Lorentzian\nlineshapes by enhanced inter-peak absorption. This is a manifestation of pure\ndephasing which should be possible to measure in near-field experiments.",
        "positive": "Influence of water intercalation and hydration on chemical decomposition\n  and ion transport in methylammonium lead halide perovskites: The use of methylammonium (MA) lead halide perovskites \\ce{CH3NH3PbX3} (X=I,\nBr, Cl) in perovskite solar cells (PSCs) has made great progress in performance\nefficiency during recent years. However, the rapid decomposition of \\ce{MAPbI3}\nin humid environments hinders outdoor application of PSCs, and thus, a\ncomprehensive understanding of the degradation mechanism is required. To do\nthis, we investigate the effect of water intercalation and hydration of the\ndecomposition and ion migration of \\ce{CH3NH3PbX3} using first-principles\ncalculations. We find that water interacts with \\ce{PbX6} and MA through\nhydrogen bonding, and the former interaction enhances gradually, while the\nlatter hardly changes when going from X=I to Br and to Cl. Thermodynamic\ncalculations indicate that water exothermically intercalates into the\nperovskite, while the water intercalated and monohydrated compounds are stable\nwith respect to decomposition. More importantly, the water intercalation\ngreatly reduces the activation energies for vacancy-mediated ion migration,\nwhich become higher going from X=I to Br and to Cl. Our work indicates that\nhydration of halide perovskites must be avoided to prevent the degradation of\nPSCs upon moisture exposure."
    },
    {
        "anchor": "Physical properties of Thallium-Tellurium based thermoelectric compounds\n  using first-principles simulations: We present a study of the thermodynamic and physical properties of Tl5Te3,\nBiTl9Te6 and SbTl9Te6 compounds by means of density functional theory based\ncalculations. The optimized lattice constants of the compounds are in good\nagreement with the experimental data. The electronic density of states and band\nstructures are calculated to understand the bonding mechanism in the three\ncompounds. The indirect band gap of BiTl9Te6 and SbTl9Te6 compounds are found\nto be equal to 0.256 eV and 0.374 eV, respectively. The spin-orbit coupling has\nimportant effects on the electronic structure of the two semiconducting\ncompounds and should therefore be included for a good numerical description of\nthese materials. The elastic constants of the three compounds have been\ncalculated, and the bulk modulus, shear modulus, and young's modulus have been\ndetermined. The change from ductile to brittle behavior after Sb or Bi alloying\nis related to the change of the electronic properties. Finally, the Debye\ntemperature, longitudinal, transverse and average sound velocities have been\nobtained.",
        "positive": "Iridium-doping as a strategy to realize visible light absorption and\n  p-type behavior in BaTiO3: BaTiO3 is typically a strong n-type material with tuneable optoelectronic\nproperties via doping and controlling the synthesis conditions. It has a wide\nband gap that can only harness the ultraviolet region of the solar spectrum.\nDespite significant progress, achieving visible-light absorbing BTO with\ntuneable carrier concentration has been challenging, a crucial requirement for\nmany applications. In this work, a p-type BTO with visible-light absorption is\nrealized via iridium doping. Detailed analysis using advanced spectroscopy\ntools and computational electronic structure analysis is used to rationalize\nthe n- to p-type transition after Ir doping. Results offered mechanistic\ninsight into the interplay between the dopant site occupancy, the dopant\nposition within the band gap, and the defect chemistry affecting the carrier\nconcentration. A decrease in the Ti3+ donor levels concentration and the\nmutually correlated oxygen vacancies upon Ir doping is attributed to the p-type\nbehavior. Due to the formation of Ir3+ or Ir4+ in-gap energy levels within the\nforbidden region, the optical transition can be elicited from or to such levels\nresulting in visible-light absorption. This newly developed Ir-doped BTO can be\na promising p-type perovskite-oxide with imminent applications in solar fuel\ngeneration, spintronics and optoelectronics."
    },
    {
        "anchor": "Emissive Azobenzenes Delivered on a Silver Coordination Polymer: Azobenzene has become a ubiquitous component of functional molecules and\npolymeric materials because of the light-induced trans-cis isomerization of the\ndiazene group. In contrast, there are very few applications utilizing\nazobenzene luminescence, since the excitation energy typically dissipates via\nnonradiative pathways. Inspired by our earlier studies with\n2,2'-bis[N,N'-(2-pyridyl)methyl]diaminoazobenzene (AzoAMoP) and related\ncompounds, we investigated a series of five aminoazobenzene derivatives and\ntheir corresponding silver complexes. Four of the aminoazobenzene ligands,\nwhich exhibit no emission under ambient conditions, form silver coordination\npolymers that are luminescent at room temperature. AzoAEpP\n(2,2'-bis[N,N'-(4-pyridyl)ethyl]diaminoazobenzene) assembles into a\nthree-dimensional coordination polymer (AgAAEpP) that undergoes a reversible\nloss of emission upon the addition of metal-coordinating analytes such as\npyridine. The switching behavior is consistent with the disassembly and\nreassembly of the coordination polymer driven by displacement of the\naminoazobenzene ligands by coordinating analytes.",
        "positive": "A Precise Packing Sequence for Self-Assembled Convex Structures: Molecular simulations of the self-assembly of cone-shaped particles with\nspecific, attractive interactions are performed. Upon cooling from random\ninitial conditions, we find that the cones self assemble into clusters and that\nclusters comprised of particular numbers of cones (e.g. 4 - 17, 20, 27, 32, 42)\nhave a unique and precisely packed structure that is robust over a range of\ncone angles. These precise clusters form a sequence of structures at specific\ncluster sizes- a precise packing sequence - that for small sizes is identical\nto that observed in evaporation-driven assembly of colloidal spheres. We\nfurther show that this sequence is reproduced and extended in simulations of\ntwo simple models of spheres self-assembling from random initial conditions\nsubject to certain convexity constraints. This sequence contains six of the\nmost common virus capsid structures obtained in vivo including large chiral\nclusters, and a cluster that may correspond to several non-icosahedral,\nspherical virus capsid structures obtained in vivo. Our findings suggest this\nprecise packing sequence results from free energy minimization subject to\nconvexity constraints and is applicable to a broad range of assembly processes."
    },
    {
        "anchor": "Lattice dynamics of altermagnetic ruthenium oxide RuO$_{2}$: Altermagnetic ruthenium oxide RuO$_{2}$ crystallizes with P4$_{2}$/mnm\nsymmetry. Here we discuss the lattice dynamics of this structure. We show and\ndiscuss the phonon dispersion and density of states. The phonon dispersion\ncurves contain several Dirac nodal lines and highly degenerate Dirac points. We\npresent the characteristic frequencies and their irreducible representations at\nthe $\\Gamma$ point. Theoretically obtained frequencies of the Raman active\nmodes nicely reproduce the ones reported experimentally.",
        "positive": "The diffraction volume for square-shaped samples in X-ray diffraction\n  with high spatial resolution: X-ray diffraction with high spatial resolution is a prerequisite for the\ncharacterization of (poly)-crystalline materials on micro- or nanoscopic\nscales. This can be achieved by utilizing a focused X-ray beam and scanning of\nthe sample. However, due to the penetration of the X-rays into the material,\nthe exact location of diffraction within the sample is ambiguous. Here, we\nutilize numerical simulations to compute the spatially resolved diffraction\nvolume in order to investigate these ambiguities. We demonstrate that partial\ndepth sensitivity can be achieved by rotating the sample."
    },
    {
        "anchor": "Resonant phonon-magnon interactions in free-standing metal-ferromagnet\n  multilayer structures: We analyze resonant magneto-elastic interactions between standing\nperpendicular spin wave modes (exchange magnons) and longitudinal acoustic\nphonon modes in free-standing hybrid metal-ferromagnet bilayer and trilayer\nstructures. Whereas the ferromagnetic layer acts as a magnetic cavity, all\nmetal layers control the frequencies and eigenmodes of acoustic vibrations. The\nhere proposed design allows for achieving and tuning the spectral and spatial\nmodes overlap between phonons and magnons that results in their strong resonant\ninteraction. Realistic simulations for gold-nickel multilayers show that\nsweeping the external magnetic field should allow for observing resonantly\nenhanced interactions between individual magnon and phonon modes in a broad\nrange of frequencies spanning from tens of GHz up to several hundreds of GHz,\nwhich can be finely tuned through the multilayer design. Our results would\nenable the systematic study and the deep understanding of resonantly enhanced\nmagneto-elastic coupling between individual phonon and magnon modes up to\nfrequencies of great contemporary fundamental and applied interest.",
        "positive": "Origin of the Enhanced Polarization in La and Mg Co-substituted BiFeO3\n  Thin Film during the Fatigue Process: We have studied the polarization fatigue of La and Mg co-substituted BiFeO3\nthin film, where a polarization peak is observed during the fatigue process.\nThe origin of such anomalous behavior is analyzed on the basis of the defect\nevolution using temperature-dependent impedance spectroscopy. It shows that the\nmotion of oxygen vacancies (VO..) is associated with a lower energy barrier,\naccompanied by the injection of electrons into the film during the fatigue\nprocess. A qualitative model is proposed to explain the fatigue behavior, which\ninvolves the modification of the Schottky barrier upon the accumulation of VO..\nat the metal-dielectric interface."
    },
    {
        "anchor": "Strain-Induced Magnetic Anisotropy in Epitaxial Thin Films of the Spinel\n  CoCr$_2$O$_4$: We show that the magnetic anisotropy in spinel-structure CoCr$_2$O$_4$ thin\nfilms exhibits a strain dependence in which compressive strain induces an\nout-of-plane magnetic easy axis and tensile strain an in-plane easy axis,\nexactly opposite to the behavior reported for the related compound\nCoFe$_2$O$_4$. We use density functional theory calculations within the LSDA+U\napproximation to reproduce and explain the observed behavior. Using\nsecond-order perturbation theory, we analyse the anisotropy tensor of the\nCo$^{2+}$ ions in both octahedral and tetrahedral coordination, allowing us to\nextend our results to spinels with general arrangements of Co$^{2+}$ ions.",
        "positive": "An Efficient Molecular Dynamics Scheme for Predicting Dopant Implant\n  Profiles in Semiconductors: We present a highly efficient molecular dynamics scheme for calculating the\nconcentration profile of dopants implanted in group-IV alloy, and III-V zinc\nblende structure materials. Our program incorporates methods for reducing\ncomputational overhead, plus a rare event algorithm to give statistical\naccuracy over several orders of magnitude change in the dopant concentration.\n  The code uses a molecular dynamics (MD) model, instead of the binary\ncollision approximation (BCA) used in implant simulators such as TRIM and\nMarlowe, to describe ion-target interactions. Atomic interactions are described\nby a combination of `many-body' and screened Coulomb potentials. Inelastic\nenergy loss is accounted for using a Firsov model, and electronic stopping is\ndescribed by a Brandt-Kitagawa model which contains the single adjustable\nparameter for the entire scheme. Thus, the program is easily extensible to new\nion-target combinations with the minimum of tuning, and is predictive over a\nwide range of implant energies and angles.\n  The scheme is especially suited for calculating profiles due to low energy,\nlarge angle implants, and for situations where a predictive capability is\nrequired with the minimum of experimental validation. We give examples of using\nour code to calculate concentration profiles and 2D `point response' profiles\nof dopants in crystalline silicon, silicon-germanium blends, and\ngallium-arsenide. We can predict the experimental profile over five orders of\nmagnitude for <100> and <110> channeling and for non-channeling implants at\nenergies up to hundreds of keV."
    },
    {
        "anchor": "Local field of magnetic islands: role of their shape: I analyze in details distribution of local magnetic field induced by micro-\nand nano-magnets. I consider three kinds of elongated magnetic islands:\nellipse-, diamond- and rectangular shaped islands which were magnetized\nuniformly along long axis. This report concentrates on the role of their shape\nupon distribution of the field. Calculations show that unlike\nrectangular-shaped magnet, ellipse-shaped and diamond-shaped ones produce much\nmore localized field in proximity of its magnetic poles. Additionally in the\ncase of ellipse-shaped islands the magnitude of induced field is large. This\ntwo facts favor arrays of ellipse-shaped magnetic islands to build\nzero-dimensional spin traps in a hybrid based on Ferromagnet/Semiconductor\nstructure.",
        "positive": "Ab initio investigation of hydrogen bonding and electronic structure of\n  high-pressure phases of ice: We report a detailed ab initio investigation on hydrogen bonding, geometry,\nelectronic structure, and lattice dynamics of ice under a large high pressure\nrange, including the ice X phase (55-380GPa), the previous theoretically\nproposed higher-pressure phase ice XIIIM (Refs. 1-2) (380GPa), ice XV (a new\nstructure we derived from ice XIIIM) (300-380GPa), as well as the ambient\npressure low-temperature phase ice XI. Different from many other materials, the\nband gap of ice X is found to be increasing linearly with pressure from 55GPa\nup to 290GPa, the electronic density of states (DOS) shows that the valence\nbands have a tendency of red shift (move to lower energies) referring to the\nFermi energy while the conduction bands have a blue shift (move to higher\nenergies). This behavior is interpreted as the high pressure induced change of\ns-p charge transfers between hydrogen and oxygen. It is found that ice X exists\nin the pressure range from 75GPa to about 290GPa. Beyond 300GPa, a new\nhydrogen-bonding structure with 50% hydrogen atoms in symmetric positions in\nO-H-O bonds and the other half being asymmetric, ice XV, is identified. The\nphysical mechanism for this broken symmetry in hydrogen bonding is revealed."
    },
    {
        "anchor": "Ferroelectricity driven magnetism at domain walls in LaAlO$_3$/PbTiO$_3$\n  superlattices: Charge dipole moment and spin moment rarely coexist in single-phase bulk\nmaterials except in some multiferroics. Despite the progress in the past\ndecade, for most multiferroics their magnetoelectric performance remains poor\ndue to the intrinsic exclusion between charge dipole and spin moment. As an\nalternative approach, the oxide heterostructures may evade the intrinsic limits\nin bulk materials and provide more attractive potential to realize the\nmagnetoelectric functions. Here we perform a first-principles study on\nLaAlO$_3$/PbTiO$_3$ superlattices. Although neither of the components is\nmagnetic, magnetic moments emerge at the ferroelectric domain walls of\nPbTiO$_3$ in these superlattices. Such a twist between ferroelectric domain and\nlocal magnetic moment, not only manifests an interesting type of\nmultiferroicity, but also is possible useful to pursuit the electrical-control\nof magnetism in nanoscale heterostructures.",
        "positive": "Giant Magnetoelectric coupling in Single Phase\n  Pb(Zr0.20Ti0.80)0.70Pd0.30O3-\u03b4 Multiferroics: During the last fifteen years, multiferroic (MF) research communities have\nbeen searching for an alternative room temperature MF material with large\nmagnetoelectric (ME) coupling for possible applications in high density\nelectronic components, low heat dissipation memory and logic devices. We have\nstudied Pb(Zr0.20Ti0.80)0.70Pd0.30O3-{\\delta} (PZTP30) system with an unusually\nlarge (30%) palladium occupancy in B site of PZT. This material exhibited a\ngiant ME coupling coefficient ~0.36 mV/cm.Oe. Interestingly, this is the first\ntime any room temperature single phase compound that showed ME trends, and\nmagnitude similar to those in the well established mechanical strain-mediated\nferroelectric and ferromagnetic composites; the latter ones are already in the\ncommercial stage as nT/pT magnetic field sensors due to their large ME values.\nThe presence of Pd in PZTP30 has been confirmed by XPS and XRF studies and\nassigned with related binding energies of Pd+2 and Pd+4 ions as 336.37 eV,\n342.9 eV, and 337.53 eV, 343.43 eV, respectively, which may be the origin of\nroom temperature magnetism in Pd substituted PZT ceramics. A sharp first order\nferroelectric phase transition was observed at ~569 K (+/-5 K) that is\nconfirmed from dielectric, Raman, and thermal analysis. Both ferromagnetic and\nferroelectric orderings with large ME coupling were found above room\ntemperature, a significant step forward in the development of single phase ME\nmaterial with enhanced functionalities."
    },
    {
        "anchor": "Effect of Rare-Earth Ions on an Electric Polarization Induced by the\n  Phase Separation Domains in RMn2O5 (R = Er, Tb): The effect of rare-earth ions (R = Er^{3+}, Tb^{3+}) with strong spin-orbit\ncoupling on the dielectric properties and the electric polarization induced by\nlocal polar phase separation domains in RMn_2O_5 multiferroics has been\nstudied. These parameters were found to be qualitatively distinguished from\nthose studied before in GdMn_2O_5, in which Gd^{3+} ion in the ground ^8S_{7/2}\nstate is weakly bounded with the lattice. It is shown that the properties of\nthe polar phase separation domains, which form in the subsystem of Mn^{3+} and\nMn^{4+} ions, are substantially dependent on the values of crystal fields, in\nwhich these domains exist.",
        "positive": "Humidity effects on tip-induced polarization switching in lithium\n  niobate: Interest to ferroelectric materials has been increased significantly in last\ndecades due to development of new generation of nonlinear optical and data\nstorage devices. Scanning probe microscopy (SPM) can be used both for study of\ndomain structures with nanoscale spatial resolution and for writing the\nisolated nanodomains by local application of the electric field. Tip-induced\nswitching in the ambient still needs experimental investigations and\ntheoretical explorations. Here we studied influence of the value of relative\nhumidity in the SPM chamber on the process of tip-induced polarization\nswitching. This phenomenon was attributed to existing of the water meniscus\nbetween tip and the sample surface in humid atmosphere. Presented results are\nimportant for further complex investigations of the ferroelectric materials and\ntheir applications."
    },
    {
        "anchor": "Hot carrier redistribution, electron-phonon interaction, and their role\n  in carrier relaxation in thin film halide perovskites: Temperature dependent (4K-300K) photoluminescence and transmission spectra\nare analyzed to study the effect of changing the different components of a\nperovskite compound, be it A, B, or X. Four different films are compared:\nFAMAPbSnI3, FAPbI3, FAMAPbI3, and FAPbBr3. The low temperature results\nhighlight the changes that occur especially, underlying ones that are easily\nmasked at room temperature. The overall Stokes shift is of similar magnitude at\nroom temperature for the 3 Pb only based samples. This is governed by the\ninteraction strength GammaLO, phonon energy ELO, and the exciton binding energy\nEex. One exception to this behavior is the Sn-based FAMAPbSnI3 film which shows\na lack of Stokes shift between the absorption and photoluminescence.\nHowever,the strong absorption (more than 100 meV) below the band gap is\nindicative of an excitonic feature that has a large density of states.\nTransient absorption measurements confirm the trends observed in continuous\nwave (CW) measurements, the 3 Pb only films all show the convolution of an\nexcitonic feature within 20 meV of the band gap as a contributing factor to the\nphotobleach along with a region of high energy PIA. However, the behavior for\nthe Sn-based film is notably different (just as in the CW measurements) with an\nunusual low energy PIA and a lack of high energy PIA. The large low energy PIA\nis attributed to the large sub band gap absorption observed in the CW\ntransmission/absorption measurements. Notably regardless of interchanging\ncomponents, the slow cooling of carriers in metal-halide perovsites shows\nlittle effect of GammaLO, ELO, and Eex. As such, here it is proposed: while the\ninitial cooling of carriers is attributed to LO phonons, the overall cooling of\ncarriers is dominated by the intrinsic low thermal conductivity of all\nmetal-halide perovskites which limits the dissipation of acoustic phonons in\nthese systems.",
        "positive": "Defect studies in strain-relaxed Si$_{1-x}$Ge$_x$ alloys: Raman light scattering, low-temperature photoluminescence, light-scattering\ntomography, and hydrogenation were used to investigate optical properties of\ndefects in strain-relaxed Si_{1-x}Ge_x (0.05 \\le x \\le 0.50) alloys. The\nphotoluminescence emission was characterized by typical zero-phonon,\nphonon-assisted, and dislocations-related emissions, which are dependent on Ge\ncomposition x. However, luminescence spectra exhibited above band-gap features,\nwhich are likely associated with the presence of Si-rich regions in the alloys.\nThe results are correlated with light-scattering tomography, revealing the\npresence of dislocations and Si precipitates. The excess peak at 519 cm^{-1} in\nGe-rich samples is supportive of this observation. At low Ge content, a\ndislocation-related band (D2 line) at 14,204 {\\AA} dominates D-band emission\nfor x < 0.25 while overall D-band emission intensity decreases with x.\nHydrogenation was found to enhance D-band emission, indicating a passivation of\nnonradiative recombination centers inside dislocation cores. Si-Si, Si-Ge, and\nGe-Ge phonons (TO, TA, and LA), which are participating in luminescence\nemission, evolve with increasing Ge content and Ge-Ge and Si-Ge TO lines\ndominate the Raman spectrum to the detriment of the Si-Si TO phonon line. Raman\nspectra reveal the presence of alloy fluctuations and possible presence of Ge\nparticles, particularly in Ge-rich samples."
    },
    {
        "anchor": "Physical Effects in the Vicinity of the Ferroelectric-Antiferroelectric\n  Interface: Physical effects caused by the presence of interfaces between the domains of\ncoexisting ferroelectric and antiferroelectric phases in solid solutions with\nsmall difference in free energies of the ferroelectric and antiferroelectric\nstates are discussed in this review. There exist a number of solid solutions in\nwhich the two-phase state of domains of the coexisting phases may occur under\ncertain conditions. We present here results of investigations of some effects\ndirectly caused by the presence of the interfaces between the domains of the\ncoexisting ferroelectric and antiferroelectric phases. The phenomenological\nmodel describing the inhomogeneous state of coexisting domains of the\nferroelectric and antiferroelectric phases is presented. Experimental studies\nof such inhomogeneous state are discussed using two systems of the\nPbZr1-yTiyO3-based solid solutions. Detailed discussion of the process of local\ndecomposition of solid solutions in the vicinity of\nferroelectric-antiferroelectric interphase boundaries and formation of the\nmesoscopic system of segregates in the vicinity of these interphase boundaries\nand corresponding experimental results are presented. Results on influence of\nthe system of segregates on dielectric and piezoelectric properties, and also\non a dielectric relaxation are presented and discussed. The effects caused by\nthe application of a DC electric field are considered and corresponding\nexperimental results are presented. The experimental results demonstrating the\npossibility of control of piezoelectric parameters by an external electric\nfield in materials with the antiferroelectric to ferroelectric phase transition\nvia the intermediate state of the coexisting domains of these phases are given.",
        "positive": "Vibrational and electron-phonon coupling properties of \\b{eta}-Ga2O3\n  from first-principles calculations: Impact on the mobility and breakdown\n  field: The wide band gap semiconductor \\b{eta}-Ga2O3 shows promise for applications\nin high-power and high-temperature electronics. The phonons of \\b{eta}-Ga2O3\nplay a crucial role in determining its important material characteristics for\nthese applications such as its thermal transport, carrier mobility, and\nbreakdown voltage. In this work, we apply predictive calculations based on\ndensity functional theory and density functional perturbation theory to\nunderstand the vibrational properties, phonon-phonon interactions, and\nelectron-phonon coupling of \\b{eta}-Ga2O3. We calculate the directionally\ndependent phonon dispersion, including the effects of LO-TO splitting and\nisotope substitution, and quantify the frequencies of the infrared and\nRaman-active modes, the sound velocities, and the heat capacity of the\nmaterial. Our calculated optical-mode Gr\\\"uneisen parameters reflect the\nanharmonicity of the monoclinic crystal structure of \\b{eta}-Ga2O3 and help\nexplain its low thermal conductivity. We also evaluate the electron-phonon\ncoupling matrix elements for the lowest conduction band to determine the phonon\nmode that limits the mobility at room temperature, which we identified as a\npolar-optical mode with a phonon energy of 29 meV. We further apply these\nmatrix elements to estimate the breakdown field of \\b{eta}-Ga2O3. Our\ntheoretical characterization of the vibrational properties of \\b{eta}-Ga2O3\nhighlights its viability for high-power electronic applications and provides a\npath for experimental development of materials for improved performance in\ndevices."
    },
    {
        "anchor": "Five-fold Symmetry in Au-Si Metallic Glass: The first metallic glass of Au-Si alloy has been discovered for over half a\ncentury, but its atomic structure is still puzzling. Herein, Au 8 Si\ndodecahedrons with local five-fold symmetry are revealed as building blocks in\nAu-Si metallic glass, and the interconnection modes of Au 8 Si dodecahedrons\ndetermine the medium-range order. With dimensionality reduction, the surface\nordering is attributed to the motif transformation of Au 8 Si dodecahedrons\ninto planar Au 5 Si pyramids with five-fold symmetry, and thus the\nself-assembly of Au 5 Si pyramids leads to the formation of the ordered Au 2 Si\nmonolayer with the lowest energy. Furthermore, the structural similarity\nanalysis is performed to unveil the physical origin of structural\ncharacteristics in different dimensions. The amorphism of Au-Si is due to the\nsmooth energy landscape around the global minimum, while the ordered surface\nstructure occurs due to the steep energy landscape.",
        "positive": "Domain structure and perpendicular magnetic anisotropy in CoFe/Pd\n  multilayers using off-axis electron holography: Multilayers of Co90Fe10/Pd with different bilayer thicknesses, have been\ndeposited by dc-magnetron sputtering on thermally oxidized Si wafers.\nTransmission electron microscopy showed that the highly textured crystalline\nfilms had columnar structure, while scanning transmission electron microscopy\nand atomic force microscopy respectively indicated some layer waviness and\nsurface roughness. The magnetic domain structure and perpendicular magnetic\nanisotropy (PMA) of the Co90Fe10/Pd multilayers were investigated by off-axis\nelectron holography and magnetic force microscopy. The Co90Fe10 layer thickness\nwas the primary factor determining the magnetic domain size and the\nperpendicular magnetization: both decreased as the thickness increased. The\nstrongest PMA was observed in the sample with the thinnest magnetic layer of\n0.45 nm."
    },
    {
        "anchor": "Valley polarization generated in 3-dimensional group-IV monochalcogenids: Valleytronics is one of the breaking-through to the technology of\nelectronics, which provides a new degree of freedom to manipulate the\nproperties of electrons. Combining DFT calculations, optical absorption\nanalysis and the linear polarization-resolved transmission measurement\ntogether, we report that three pairs of valleys, which feature opposite optical\nabsorption, existing in the 3-dimensional (3D) group-IV monochalcogenids. By\napplying the linearly-polarized light, valley polarization is successfully\ngenerated for the first time in a 3D system, which opens a new direction for\nthe exploration of the valley materials and provides a good platform for the\nphotodetector and valleytronic devices. Valley modulation versus the in-plane\nstrain in GeSe is also studied, suggesting an effective way to get the\noptimized valleytronic properties.",
        "positive": "Aggregation and Electronically-Induced Migration of Oxygen Vacancies in\n  TiO2 Anatase: The influence of the electric field and electric current on the behavior of\noxygen vacancies (VOs) in TiO2 anatase was investigated with Scanning Tunneling\nMicroscopy (STM). At the anatase (101) surface VOs are not stable; they migrate\ninto the bulk at temperatures above 200 K. Scanning a clean anatase (101)\nsurface at a sample bias greater than +4.3 V results in surface VOs in the\nscanned area, suggesting that subsurface VOs migrate back to the surface. To\ntest this hypothesis, surface VOs were first created through bombardment with\nenergetic electrons. The sample was then mildly annealed, which caused the VOs\nto move to the subsurface region, where they formed vacancy clusters. These VO\nclusters have various, distinct shapes. Scanning VO clusters with a high STM\nbias reproducibly converts them back into groupings of surface VO, with a\nconfiguration that is characteristic for each type of cluster. The dependence\nof the subsurface-to-surface VO migration on the applied STM bias voltage,\ntunneling current, and sample temperature was investigated systematically. The\nresults point towards a key role of energetic, 'hot' electrons in this process.\nThe findings are closely related to the memristive behavior of oxides and\noxygen diffusion in solid-oxide membranes."
    },
    {
        "anchor": "Van der Waals Epitaxy of Pulsed Laser Deposited Antimony Thin Films on\n  Lattice-matched and Amorphous Substrates: Monatomic antimony thin films have recently attracted attention for\napplications in phase change memory, nanophotonics, and 2D materials. Although\nsome promising results have been reported, the true potential of Sb thin films\nis still hindered by the scalability issue and the lack of reliable bottom-up\nproduction. Here we demonstrate the growth of Sb thin films on a\nlattice-matching and amorphous substrates using pulsed laser deposition (PLD).\nC-axis out-of-plane textured Sb thin films were successfully deposited on\nSb$_2$Te$_3$ and SiO$_2$\\Si$_3$N$_4$ substrates. In the case of growth on\nSb$_2$Te$_3$, we show that an intermediate phase is formed at the\nSb$_2$Te$_3$-Sb interface playing a crucial role in forming a solid coupling\nand thus maintaining epitaxy leading to the production of high-quality Sb thin\nfilms. A 3 - 4 nm amorphous Sb seed layer was used to induce texture and\nsuitable surface termination for the growth of Sb thin films on amorphous\nsubstrates. The deposition parameters were fine-tuned, and the growth was\nmonitored in situ by a Reflective High Energy Electron Diffraction (RHEED).\nScanning/Transmission Electron Microscopy (S/TEM) unveiled the local structure\nof produced films showing the formation of $\\beta$-phase Sb thin films. Our\nresults demonstrate the feasibility to produce very smooth high-quality\nantimony thin films with uniform coverage, from few layers to large\nthicknesses, using pulsed laser deposition. We believe the results of our work\non scalable and controllable Sb growth have the potential to open up research\non phase-change materials and optoelectronics research.",
        "positive": "Lattice dynamics and phonon softening in Ni-Mn-Al Heusler alloys: Inelastic and elastic neutron scattering have been used to study a single\ncrystal of the Ni$_{54}$Mn$_{23}$Al$_{23}$ Heusler alloy over a broad\ntemperature range. The paper reports the first experimental determination of\nthe low-lying phonon dispersion curves for this alloy system. We find that the\nfrequencies of the TA$_2$ modes are relatively low. This branch exhibits an\nanomaly (dip) at a wave number $\\xi_{0} ={1/3}\\approx 0.33$, which softens with\ndecreasing temperature. Associated with this anomalous dip at $\\xi_{0}$, an\nelastic central peak scattering is also present. We have also observed\nsatellites due to the magnetic ordering."
    },
    {
        "anchor": "Polarity Reversed Robust Carrier Mobility in Monolayer MoS2 Nanoribbons: Using first-principles calculations and deformation potential theory, we\ninvestigate the intrinsic carrier mobility ({\\mu}) of monolayer MoS2 sheet and\nnanoribbons. In contrast to the dramatic three orders of magnitude of\ndeterioration of {\\mu} in graphene upon forming nanoribbons, the magnitude of\n{\\mu} in armchair MoS2 nanoribbons is comparable to that in monolayer MoS2\nsheet, albeit oscillating with width. Surprisingly, a room-temperature\ntransport polarity reversal is observed with {\\mu} of hole (h) and electron (e)\nbeing 200.52 (h) and 72.16 (e) cm2V-1s-1 in sheet, and 49.72 (h) and 190.89 (e)\ncm2V-1s-1 in 4 nm-wide nanoribbon. The robust magnitudes of {\\mu} and polarity\nreversal are attributable to the different characteristics of edge states\ninherent in MoS2 nanoribbons. Our study suggests that width-reduction together\nwith edge engineering provide a promising route for improving the transport\nproperties of MoS2 nanostructures.",
        "positive": "Azobenzene versus 3,3',5,5'-tetra-tert-butyl-azobenzene (TBA) at\n  Au(111): Characterizing the role of spacer groups: We present large-scale density-functional theory (DFT) calculations and\ntemperature programmed desorption measurements to characterize the structural,\nenergetic and vibrational properties of the functionalized molecular switch\n3,3',5,5'-tetra-tert-butyl-azobenzene (TBA) adsorbed at Au(111). Particular\nemphasis is placed on exploring the accuracy of the semi-empirical dispersion\ncorrection approach to semi-local DFT (DFT-D) in accounting for the substantial\nvan der Waals component in the surface chemical bond. In line with previous\nfindings for benzene and pure azobenzene at coinage metal surfaces, DFT-D\nsignificantly overbinds the molecule, but seems to yield an accurate adsorption\ngeometry as far as can be judged from the experimental data. Comparing the\ntrans adsorption geometry of TBA and azobenzene at Au(111) reveals a remarkable\ninsensitivity of the structural and vibrational properties of the -N=N- moiety.\nThis questions the established view of the role of the bulky tert-butyl-spacer\ngroups for the switching of TBA in terms of a mere geometric decoupling of the\nphotochemically active diazo-bridge from the gold substrate."
    },
    {
        "anchor": "Comment on the \"Origin of the opalescence at the \u03b1--\u03b2\n  transition of quartz: role of the incommensurate phase studied by synchrotron\n  radiation\": The interpretation of the origin of the light scattering anomalies near the\ntransition from incommensurate (IC) to the alpha-phase of quartz by Dolino et\nal. (Phys. Rev. Lett. 94, 155701 (2005)) is commented. It is shown that the\nobserved IC structure is a pure transverse acoustic (TA) modulation without any\nsoft optic mode component. Such a modulation cannot be responsible for the\nobserved light scattering contrary to the interpretation by Dolino et al.",
        "positive": "Assessing the quality of relaxation-time approximations with\n  fully-automated computations of phonon-limited mobilities: The mobility of carriers, as limited by their scattering with phonons, can\nnow routinely be obtained from first-principles electron-phonon coupling\ncalculations. However, so far, most computations have relied on some form of\nsimplification of the linearized Boltzmann transport equation based on either\nthe self-energy, the momentum- or constant relaxation time approximations.\nHere, we develop a high-throughput infrastructure and an automatic workflow and\nwe compute 69 phonon-limited mobilities in semiconductors. We compare the\nresults resorting to the approximations with the exact iterative solution. We\nconclude that the approximate values may deviate significantly from the exact\nones and are thus not reliable. Given the minimal computational overhead, our\nwork encourages to rely on this exact iterative solution and warns on the\npossible inaccuracy of earlier results reported using relaxation time\napproximations."
    },
    {
        "anchor": "Origin of indirect optical transitions in few-layer MoS2, WS2 and WSe2: It has been well established that single layer MX2 (M=Mo,W and X=S,Se) are\ndirect gap semiconductors with band edges coinciding at the K point in contrast\nto their indirect gap multilayer counterparts. In few-layer MX2, there are two\nvalleys along the {\\Gamma}-K line with similar energy. There is little\nunderstanding on which of the two valleys forms the conduction band minimum\n(CBM) in this thickness regime. We investigate the conduction band valley\nstructure in few-layer MX2 by examining the temperature-dependent shift of\nindirect exciton PL. Hihgly anisotropic thermal expansion of the lattice and\ncorresponding evolution of the band structure result in distinct peak shift for\nindirect transitions involving the K and {\\Lambda} (midpoint along {\\Gamma}-K)\nvalleys. We identify the origin of the indirect emission and concurrently\ndetermine the relative energy of these valleys. Our results show that the two\nvalleys compete in energy in few-layer WSe2.",
        "positive": "Machine-learning-accelerated simulations to enable automatic surface\n  reconstruction: Understanding material surfaces and interfaces is vital in applications like\ncatalysis or electronics. By combining energies from electronic structure with\nstatistical mechanics, ab initio simulations can in principle predict the\nstructure of material surfaces as a function of thermodynamic variables.\nHowever, accurate energy simulations are prohibitive when coupled to the vast\nphase space that must be statistically sampled. Here, we present a bi-faceted\ncomputational loop to predict surface phase diagrams of multi-component\nmaterials that accelerates both the energy scoring and statistical sampling\nmethods. Fast, scalable, and data-efficient machine learning interatomic\npotentials are trained on high-throughput density-functional theory\ncalculations through closed-loop active learning. Markov-chain Monte Carlo\nsampling in the semi-grand canonical ensemble is enabled by using virtual\nsurface sites. The predicted surfaces for GaN(0001), Si(111), and SrTiO3(001)\nare in agreement with past work and suggest that the proposed strategy can\nmodel complex material surfaces and discover previously unreported surface\nterminations."
    },
    {
        "anchor": "An attempt to simulate laser-induced all-optical spin switching in a\n  crystalline ferrimagnet: Interest in all-optical spin switching (AOS) is growing rapidly. The recent\ndiscovery of AOS in Mn$_2$RuGa provides a much needed clean case of crystalline\nferrimagnets for theoretical simulations. Here, we attempt to simulate it using\nthe state-of-the-art first-principles method combined with the Heisenberg\nexchange model. We first compute the spin moments at two inequivalent manganese\nsites and then feed them into our model Hamiltonian. We employ an ultrafast\nlaser pulse to switch the spins. We find that there is a similar optimal laser\nfield amplitude to switch spins. However, we find that the exchange interaction\nhas a significant effect on the system switchability. Weakening the exchange\ninteraction could make the system unswitchable. This provides a crucial insight\ninto the switching mechanism in ferrimagnets.",
        "positive": "On roughness-induced adhesion enhancement: While adhesion reduction due to roughness is not surprising, roughness\ninduced adhesion remained a puzzle until recently Guduru and coworkers have\nshown a very convincing mechanism to explain both the increase of strength and\nof toughness in a sphere with concentric single scale of waviness. Kesari and\ncoworkers have later shown some very elegant convenient asymptotic expansion of\nGuduru's solution. This enhancement is very high and indeed, using Kesari's\nsolution, it is here shown to depend uniquely on a Johnson parameter for\nadhesion of a sinusoidal contact. However, counterintuitively, it leads to\nunbounded enhancement for conditions of large roughness for which Johnson\nparameter is very low. Guduru postulated that this enhancement should occur\nafter sufficiently large pressure has been applied to any spherical contact.\nAlso, that although the enhancement is limited to the JKR regime of large soft\nmaterials with high adhesion, the DMT limit for the smooth sphere is found\notherwise. However, for hard materials, even the DMT limit for the smooth\nsolids is very hard to observe, which suggest that also adhesion reduction is\nyet not well understood.\n  The limitations of the assumption of simply connected area is here further\ndiscussed, and a well known model for hard particles in contact with rough\nplanes due to Rumpf is used to show that in the range where unbounded increase\nis predicted, orders of magnitude reduction is instead expected for rigid\nsolids. We suggest that Guduru's model may be close to an upper bound to\nadhesion of rough bodies, while the Rumpf-Rabinovich model may be close to a\nlower bound."
    },
    {
        "anchor": "Reliability Evaluation Method for Electronic Device BGA Package\n  Considering the Interaction Between Design Factors: The recent development of electric and electronic devices has been\nremarkable. The miniaturization of electronic devices and high integration are\nprogressing by advances in mounting technology. As a result, the reliability of\nfatigue life has been prioritized as an important concern, since the thermal\nexpansion difference between a package and printed circuit board causes thermal\nfatigue. It is demanded a long-life product which has short development time.\nHowever, it is difficult because of interaction between each design factor. The\nauthors have investigated the influence of various design factors on the\nreliability of soldered joints in BGA model by using response surface method\nand cluster analysis. By using these techniques, the interaction of all design\nfactors was clarified. Based upon the analytical results, design engineers can\nrate each factor's effect on reliability and assess the reliability of their\nbasic design plan at the concept design stage.",
        "positive": "Anisotropic mechanical and optical response and negative Poissons ratio\n  in Mo2C nanomembranes revealed by first-principles simulations: Transition metal carbides include a wide variety of materials with attractive\nproperties that are suitable for numerous and diverse applications. Most recent\nexperimental advance could provide a path toward successful synthesis of\nlarge-area and high-quality ultrathin Mo2C membranes with superconducting\nproperties. In the present study, we used first-principles density functional\ntheory calculations to explore the mechanical and optical response of\nsingle-layer and free-standing Mo2C. Uniaxial tensile simulations along the\narmchair and zigzag directions were conducted and we found that while the\nelastic properties are close along various loading directions, nonlinear\nregimes in stress-strain curves are considerably different. We found that Mo2C\nsheets present negative Poisson's ratio and thus can be categorized as an\nauxetic material. Our simulations also reveal that Mo2C films retain their\nmetallic electronic characteristic upon the uniaxial loading. We found that for\nMo2C nanomembranes the dielectric function becomes anisotropic along in-plane\nand out-of plane directions. Our findings can be useful for the practical\napplication of Mo2C sheets in nanodevices."
    },
    {
        "anchor": "Orbital-resolved Observation of Singlet Fission: Singlet fission may boost photovoltaic efficiency [by transforming a singlet\nexciton into two triplet excitons and thereby doubling the number of excited\ncharge carriers. The primary step of singlet fission is the ultrafast creation\nof the correlated triplet pair. While several mechanisms have been proposed to\nexplain this step, none has emerged as a consensus. The challenge lies in\ntracking the transient excitonic states. Here we use time- and angle-resolved\nphotoemission spectroscopy to observe the primary step of singlet fission in\ncrystalline pentacene. Our results suggest a charge-transfer mediated mechanism\nwith a hybridization of Frenkel and charge-transfer states in the lowest bright\nsinglet exciton. We gained intimate knowledge about the localization and the\norbital character of the exciton wave functions recorded in momentum maps. This\nallowed us to directly compare the localization of singlet and bitriplet\nexcitons and decompose energetically overlapping states based on their orbital\ncharacter. Orbital- and localization- resolved many-body dynamics promise deep\ninsights into the mechanics governing molecular systems and topological\nmaterials.",
        "positive": "Continuum model for hydrogen pickup in Zirconium alloys of LWR fuel\n  cladding: A continuum model for calculating the time-dependent hydrogen pickup\nfractions in various Zirconium alloys under steam and pressured water oxidation\nhas been developed in this study. Using only one fitting parameter, the\neffective hydrogen gas partial pressure at the oxide surface, a qualitative\nagreement is obtained between the predicted and previously measured hydrogen\npickup fractions. The calculation results therefore demonstrate that H\ndiffusion through the dense oxide layer plays an important role in the hydrogen\npickup process. The limitations and possible improvement of the model are also\ndiscussed."
    },
    {
        "anchor": "Electronic structure and phase stability of oxide semiconductors:\n  Performance of dielectric-dependent hybrid functional DFT, benchmarked\n  against $GW$ band structure calculations and experiments: We investigate band gaps, equilibrium structures, and phase stabilities of\nseveral bulk polymorphs of wide-gap oxide semiconductors ZnO, TiO2,ZrO2, and\nWO3. We are particularly concerned with assessing the performance of hybrid\nfunctionals built with the fraction of Hartree-Fock exact exchange obtained\nfrom the computed electronic dielectric constant of the material. We provide\ncomparison with more standard density-functional theory and GW methods. We\nfinally analyze the chemical reduction of TiO2 into Ti2O3, involving a change\nin oxide stoichiometry. We show that the dielectric-dependent hybrid functional\nis generally good at reproducing both ground-state (lattice constants, phase\nstability sequences, and reaction energies) and excited-state (photoemission\ngaps) properties within a single, fully ab initio framework.",
        "positive": "Native defects and their complexes in spinel LiGa5O8: the puzzle of\n  p-type doping: Recently, LiGa$_5$O$_8$ was identified as a cubic spinel type\nultra-wide-band-gap semiconductor with a gap of about 5.36 eV and reported to\nbe unintentionally p-type. Here we present first-principles calculations of the\nnative defects and various of their complexes to try to explain the occurrence\nof p-type doping. Although we find Li-vacancies to be somewhat shallower\nacceptors than in LiGaO$_2$, and becoming slightly shallower in complexes with\ndonors such as V$_{\\rm O}$ and Ga$_{\\rm Li}$ antisites, these $V_{\\rm Li}$\nbased defects are not sufficiently shallow to explain p-type doping. The\ndominant defects are donors and in equilibrium the Fermi level would be\ndetermined by compensation between donors and acceptors, and pinned deep in the\ngap."
    },
    {
        "anchor": "Photoemission Orbital Tomography Using Robust Sparse PhaseLift: Photoemission orbital tomography (POT) from photoelectron momentum maps\n(PMMs) has enabled detailed analysis of the shape and energy of molecular\norbitals in the adsorbed state. This study proposes a new POT method based on\nthe PhaseLift. Molecular orbitals, including three-dimensional phases, can be\nidentified from a single PMM by actively providing atomic positions and basis.\nMoreover, our method is robust to noise and can perfectly discriminate\nadsorption-induced molecular deformations with an accuracy of 0.05 [angstrom].\nOur new method enables simultaneous analysis of the three-dimensional shapes of\nmolecules and molecular orbitals and thus paves the way for advanced\nquantum-mechanical interpretation of adsorption-induced electronic state\nchanges and photo-excited inter-molecular interactions.",
        "positive": "Controlling Dipolar Interaction Effect in Two-Dimensional Magnetic\n  Nanostructures: We investigate the dependence of magnetic properties on the out-of-plane\ndisorder strength $\\Delta$, dipolar interaction strength $h^{}_d$ in\ntwo-dimensional ($l^{}_x\\times l^{}_y$) ensembles of nanoparticles using\nnumerical simulations. Such positional defects are redundantly observed in\nexperiments. The superparamagnetic character is dominant with negligible and\nweak interaction strength $h^{}_d$, irrespective of $\\Delta$ and aspect ratio\nof the system $A^{}_r=l^{}_y/l^{}_x$. The double-loop hysteresis curve,\ncharacteristics of antiferromagnetic coupling dominance, emerges with large\n$h^{}_d$ and $\\Delta(\\%)\\leq5$ in the square-like nanoparticles' assays.\nRemarkably, the dipolar interaction of sufficient strength drives the magnetic\norder from antiferromagnetic to ferromagnetic with large $\\Delta$ and\n$A^{}_r\\leq4.0$, resulting in an enhancement in the hysteresis loop area. On\nthe other hand, the ferromagnetic coupling gets increased with $h^{}_d$ in\nsystems with huge $A^{}_r$. Consequently, the hysteresis loop is enormous, even\nwith moderate $h^{}_d$. The variation of the coercive field $\\mu^{}_oH^{}_c$,\nremanence $M^{}_r$, and amount of heat released $E^{}_H$ (due to the\nhysteresis) with these parameters also suggests the transformation of nature\ndipolar interaction. They are significant even with large $h^{}_d$ and smaller\n$A^{}_r$, indicating the antiferromagnetic coupling dominance. Interestingly,\nthere is an enhancement in these with $\\Delta$ and large $h^{}_d$ due to\nferromagnetic interaction. Notably, they are very significant even with\nmoderate $h^{}_d$ in the highly anisotropic system and external field along the\nlong axis of the sample. These results could help the experimentalist in\nexplaining the unusual hysteresis characteristics observed in such systems and\nshould also be beneficial in diverse applications such as data storage,\nmagnetic hyperthermia, etc."
    },
    {
        "anchor": "Evolution of the Surface Structures on SrTiO$_3$(110) Tuned by Ti or Sr\n  Concentration: The surface structure of the SrTiO$_3$(110) polar surface is studied by\nscanning tunneling microscopy and X-ray photoelectron spectroscopy. Monophased\nreconstructions in (5$\\times$1), (4$\\times$1), (2$\\times$8), and (6$\\times$8)\nare obtained, respectively, and the evolution between these phases can be tuned\nreversibly by adjusting the Ar$^{+}$ sputtering dose or the amount of Sr/Ti\nevaporation. Upon annealing, the surface reaches the thermodynamic equilibrium\nthat is determined by the surface metal concentration. The different electronic\nstructures and absorption behaviors of the surface with different\nreconstructions are investigated.",
        "positive": "Ratiometric Organic Fibers for Localized and Reversible Ion Sensing with\n  Micrometer-Scale Spatial Resolution: A fundamental issue in biomedical and environmental sciences is the\ndevelopment of sensitive and robust sensors able to probe the analyte of\ninterest, under physiological and pathological conditions or in environmental\nsamples, and with very high spatial resolution. In this work, novel hybrid\norganic fibers that can effectively report the analyte concentration within the\nlocal microenvironment are reported. The nanostructured and flexible wires are\nprepared by embedding fluorescent pH sensors based on\nseminaphtho-rhodafluor-1-dextran conjugate. By adjusting capsule/polymer ratio\nand spinning conditions, the diameter of the fibers and the alignment of the\nreporting capsules are both tuned. The hybrid wires display excellent\nstability, high sensitivity, as well as reversible response, and their\noperation relies on effective diffusional kinetic coupling of the sensing\nregions and the embedding polymer matrix. These devices are believed to be a\npowerful new sensing platform for clinical diagnostics, bioassays and\nenvironmental monitoring."
    },
    {
        "anchor": "Phonon Anomaly In 9R-Ba0.9Sr0.1MnO3: Materials which possess coupling between different degrees of freedom such as\ncharge, spin, orbital and lattice are of tremendous interest due to their\npotential for device applications. It has been recently realized that some of\nmanganite perovskite oxides show structural and ferroelectric instabilities\nwhich may be tuned by imposing internal or external strain. Among manganite\nperovskites, AMnO3 (A = Ca, Sr and Ba) are reported to be good candidates to\nshow spin-phonon coupling driven multiferroicity. Here, we have probed the\ncorrelation between vibrational and magnetic properties in the 9R-type\nhexagonal Ba0.9Sr0.1MnO3 (BSM10). Nine Raman active modes are observed which\nare characteristic phonon modes for 9R phase. The frequency ({omega}) of an Eg\n(344 cm-1) mode which is related to Mn vibrations shows anomaly with\ntemperature (T) manifested as a change in slope of {omega} vs T at 260 K. The\ntemperature-dependent magnetization of BSM10 suggests a possible\nantiferromagnetic ordering at ~ 260 K. We, therefore, attribute the phonon\nanomaly to spin-phonon coupling arising due to the magnetic ordering.",
        "positive": "Crystal structure of cobalt hydroxide carbonate Co$_2$CO$_3$(OH)$_2$:\n  density functional theory and X-ray diffraction investigation: We have investigated the structure of Co$_2$CO$_3$(OH)$_2$ using Density\nFunctional Theory (DFT) simulations as well as Powder X-Ray Diffraction (PXRD)\nmeasurements on samples synthesized via deposition from aqueous solution. We\nconsider two possible monoclinic phases, with closely related but symmetrically\ndifferent crystal structures, based on those of the minerals malachite and\nrosasite, as well as an orthorhombic phase that can be seen as a common parent\nstructure for the two monoclinic phases, and a triclinic phase with the\nstructure of the mineral kolwezite. Our DFT simulations predict that the\nrosasite-like and the malachite-like phases are two different local minima of\nthe potential energy landscape for Co$_2$CO$_3$(OH)$_2$, and are practically\ndegenerate in energy, while the orthorhombic and triclinic structures are\nunstable and experience barrierless transformations to the malachite phase upon\nrelaxation. The best fit to the PXRD data is obtained using a rosasite model\n(monoclinic with space group P1121/n and cell parameters a = 3.1408(4) {\\AA}, b\n= 12.2914(17) {\\AA}, c = 9.3311(16) {\\AA}, $\\gamma$ = 82.299(16)$^{\\circ}$).\nHowever, some features of the PXRD pattern are still not well accounted for by\nthis refinement and the residual parameters are relatively poor. We discuss the\nrelationship between the rosasite and malachite phases of Co$_2$CO$_3$(OH)$_2$\nand show that they can be seen as polytypes. Based on the similar calculated\nstability of these two polytypes, we speculate that some level of stacking\ndisorder could account for the poor fit of our PXRD data. The possibility that\nCo$_2$CO$_3$(OH)$_2$ could crystallize, under different growth conditions, as\neither rosasite or malachite, or even as a stacking-disordered phase\nintermediate between the two, requires further investigation."
    },
    {
        "anchor": "New synthesis route and magnetic structure of Tm2Mn2O7 - pyrochlore: In this work we present a new chemical route to synthesize Tm2Mn2O7\npyrochlore, a compound which is thermodynamically unstable at ambient pressure.\nDifferently from the reported in the past high pressure synthesis of the same\ncompound applying oxides as starting materials, we have obtained a pure phase\nTm2Mn2O7 by a converting TmMnO3 at 1100 C and 1300 bar oxygen pressure. The\nstudies of Tm2Mn2O7 performed by a high resolution neutron powder diffraction\nhave shown, that a pure pyrochlore cubic phase Tm2Mn2O7 (space group Fd-3m)\nhave been obtained. On cooling below 25K there is a transition to a\nferromagnetically (FM) ordered phase observed with an additional\nantiferromagnetic (AFM) canting suggesting a lowering of the initial cubic\ncrystal symmetry. The magnetic transition is accompanied by small but well\nvisible magnetostrsiction effect. Using symmetry analysis we have found a\nsolution for the AFM structure in the maximal Shubnikov subgroup I41/am'd'.",
        "positive": "Solute-point defect interactions, coupled diffusion, and radiation\n  induced segregation in fcc nickel: Radiation-induced segregation (RIS) of solutes in materials exposed to\nirradiation is a well-known problem. It affects the life-time of nuclear\nreactor core components by favouring radiation-induced degradation phenomena\nsuch as hardening and embrittlement. In this work, RIS tendencies in\nface-centered cubic (fcc) Ni-X (X = Cr, Fe, Ti, Mn, Si, P) dilute binary alloys\nare examined. The goal is to investigate the driving forces and kinetic\nmechanisms behind the experimentally observed segregation. By means of ab\ninitio calculations, point-defect stabilities and interactions with solutes are\ndetermined, together with migration energies and attempt frequencies. Transport\nand diffusion coefficients are then calculated in a mean-field framework, to\nget a full picture of solute-defect kinetic coupling in the alloys. Results\nshow that all solutes considered, with the exception of Cr, prefer\nvacancy-mediated over interstitial-mediated diffusion during both thermal and\nradiation-induced migration. Cr, on the other hand, preferentially migrates in\na mixed-dumbbell configuration. P and Si are here shown to be enriched, and Fe\nand Mn to be depleted at sinks during irradiation of the material. Ti and Cr,\non the other hand, display a crossover between enrichment at lower\ntemperatures, and depletion in the higher temperature range. Results in this\nwork are compared with previous studies in body-centered cubic (bcc) Fe, and\ndiscussed in the context of RIS in austenitic alloys."
    },
    {
        "anchor": "Machine learning modeling of the atomic structure and physical\n  properties of alkali and alkaline-earth aluminosilicate glasses and melts: The first version of the machine learning greybox model i-Melt was trained to\npredict latent and observed properties of K$_2$O-Na$_2$O-Al$_2$O$_3$-SiO$_2$\nmelts and glasses. Here, we extend the model compositional range, which now\nallows accurate predictions of properties for glass-forming melts in the\nCaO-MgO-K$_2$O-Na$_2$O-Al$_2$O$_3$-SiO$_2$ system, including melt viscosity\n(accuracy equal or better than 0.4 log$_{10}$ Pa$\\cdot$s in the\n10$^{-1}$-10$^{15}$ log$_{10}$ Pa$\\cdot$s range), configurational entropy at\nglass transition ($\\leq$ 1 J mol$^{-1}$ K$^{-1}$), liquidus ($\\leq$ 60 K) and\nglass transition ($\\leq$ 16 K) temperatures, heat capacity ($\\leq$ 3 \\%) as\nwell as glass density ($\\leq$ 0.02 g cm$^{-3}$), optical refractive index\n($\\leq$ 0.006), Abbe number ($\\leq$ 4), elastic modulus ($\\leq$ 6 GPa),\ncoefficient of thermal expansion ($\\leq$ 1.1 10$^{-6}$ K$^{-1}$) and Raman\nspectra ($\\leq$ 25 \\%). Uncertainties on predictions also are now provided. The\nmodel offers new possibilities to explore how melt/glass properties change with\ncomposition and atomic structure.",
        "positive": "Electrophysical properties of PMN-PT-PS-PFN:Li ceramics: We present the technology of obtaining and the electrophysical properties of\na multicomponent material 0.61PMN-0.20PT-0.09PS-0.1PFN:Li (PMN-PT-PS-PFN:Li).\nThe addition of PFN into PMN-PT decreases the temperature of final sintering\nwhich is very important during technological process (addition of Li decreases\nelectric conductivity of PFN). Addition of PS i.e., PbSnO_3 (which is unstable\nin ceramic form) permits to shift the temperature of the maximum of dielectric\npermittivity. One-step method of obtaining ceramic samples from oxides and\ncarbonates has been used. XRD, microstructure, scanning calorimetry\nmeasurements and the main dielectric, ferroelectric and electromechanical\nproperties have been investigated for the obtained samples."
    },
    {
        "anchor": "Slow rupture of frictional interfaces: The failure of frictional interfaces and the spatiotemporal structures that\naccompany it are central to a wide range of geophysical, physical and\nengineering systems. Recent geophysical and laboratory observations indicated\nthat interfacial failure can be mediated by slow slip rupture phenomena which\nare distinct from ordinary, earthquake-like, fast rupture. These discoveries\nhave influenced the way we think about frictional motion, yet the nature and\nproperties of slow rupture are not completely understood. We show that slow\nrupture is an intrinsic and robust property of simple non-monotonic\nrate-and-state friction laws. It is associated with a new velocity scale\n$c_{min}$, determined by the friction law, below which steady state rupture\ncannot propagate. We further show that rupture can occur in a continuum of\nstates, spanning a wide range of velocities from $c_{min}$ to elastic\nwave-speeds, and predict different properties for slow rupture and ordinary\nfast rupture. Our results are qualitatively consistent with recent\nhigh-resolution laboratory experiments and may provide a theoretical framework\nfor understanding slow rupture phenomena along frictional interfaces.",
        "positive": "Self-assembly, structure and electronic properties of a quasiperiodic\n  lead monolayer: A quasiperiodic Pb monolayer has been formed on the five-fold surface of the\nAl-Pd-Mn quasicrystal. Growth of the monolayer proceeds via self-assembly of an\ninterconnected network of pentagonal Pb stars, which are shown to be\ntau-inflated compared to similar structural elements of the quasiperiodic\nsubstrate. Measurements of the electronic structure of the system using\nscanning tunnelling spectroscopy and ultra-violet photoemission spectroscopy\nreveal that the Pb monolayer displays a pseudo-gap at the Fermi level which is\ndirectly related to its quasiperiodic structure."
    },
    {
        "anchor": "Morphology and Optical Properties of Thin Cd3As2 Films of a Dirac\n  Semimetal Compound: Using atomic-force microscopy (AFM) and wide-band (0.02-8.5 eV) spectroscopic\nellipsometry techniques we investigated morphology and optical properties of\nCd3As2 films grown by non-reactive rf magnetron sputtering on two types of\noriented crystalline substrates (100)p-Si and (001) alpha-Al2O3. The AFM study\nrevealed grainy morphology of the films due to island incorporation during the\nfilm growth. The complex dielectric function spectra of the annealed\nCd3As2/Al2O3 films manifest pronounced interband optical transitions at 1.2 and\n3.0 eV, in excellent agreement with the theoretical calculations for the body\ncentered tetragonal Cd3As2 crystal structure. We discovered that due to\nelectronic excitations to the Cd(s) conical bands the low-energy absorption\nedge of the annealed Cd3As2 films reveals linear dependence. We found that for\nthe annealed Cd3As2 films the Cd(s) conical node may be shifted in energy by\nabout 0.08-0.18 eV above the heavy-flat As(p) valence band, determining the\noptical gap value. The as-grown Cd3As2 films exhibit the pronounced changes of\nthe electronic band structure due to doping effect associated with Cd\nnon-stoichiometry, where fine-tuning of Cd concentration may result in the\ngapless electronic band structure of Dirac semimetals.",
        "positive": "Triple point semimetal and topological phase transitions in\n  NaCu$_{3}$Te$_{2}$: Quasiparticle excitations of free electrons in condensed-matter physics,\ncharacterized by the dimensionality of the band crossing, can find their\nelementary-particle analogs in high-energy physics, such as Majorana, Weyl, and\nDirac fermions. While crystalline symmetry allows more quasiparticle\nexcitations and exotic fermions to emerge. Using symmetry analysis and {\\it\nab-initio} calculations, we propose that the 3D honeycomb crystal\nNaCu$_3$Te$_2$ hosts triply degenerate nodal points (TDNPs) which are perfectly\nseparated from the bulk states. We find a tunable phase transition between\nTDNPs and a weak TI triggered by a symmetry-allowed perturbation, and we\nfurther reveal the crucial role played by the spin-orbital coupling (SOC) for\nthe emergence of the TDNPs in this system. Such topological non-trivial ternary\ncompound not only serves as a perfect candidate for studying three-component\nfermions, but also provides a beautiful playground for understanding the\ntopological phase transitions between TDNPs, TIs and trivial insulators, which\ndistinguishes this system from other TDNP candidates."
    },
    {
        "anchor": "Positron annihilation spectroscopy for heat-treated Fe-Ga alloys and\n  their defect structure: We present the results of lifetime positron annihilation spectroscopy (PALS)\nfor the alloys Fe21Ga and Fe22.4Ga, whose defect structure is connected with\nannealing from 20 to 1000C along the phase diagram of Fe21Ga and Fe22.4Ga, at\nthe L12-A2 transitions and in the sub-lattice of the D03 phase. In frames of\nthe standard trapping model, we estimate the positron annihilation parameters\nfor the bulk metal and for the different thermal vacancies herein. Also we\ndefine concentrations of these vacancy defects, which may be helpful for\nexplanation of the physical properties of Ge-Ga alloys, including giant\nsoftening and extremal $\\lambda_{100}$ at the given inter-metallic composition.",
        "positive": "High Precision Energy Measurements from the Analysis of Wide Spectral\n  Features. Application to the fluorescence of YAG:Ce3+: Advantage is taken of a complete and precise experimental study of the\nluminescent properties of yttrium aluminium garnet doped with Ce, previously\naccomplished by other authors, to confirm the accuracy of the invoked\ntheoretical methods for dealing with the realistic calculation of the\nelectromagnetic spectra of condensed phases. The fluorescent spectra at T=0 and\nT=250 K of YAG:Ce(3+) were calculated with no adjustable parameter, giving\ncomplete agreement with experiment. The energy released by the electronic\ntransitions was determined with precision better than 5\\% the full width at\nhalf maximum of the spectral features. Thermal quenching of the fluorescent\nyield is discussed and calculated in a less accurate way, but anyway showing\ngood agreement with experiment."
    },
    {
        "anchor": "Structural and vibrational properties of nitrogen-rich energetic\n  material guanidinium 2-methyl-5-nitraminotetrazolate: We present density functional theory calculations on the crystal structure,\nequation of state, vibrational properties and electronic structure of\nnitrogen-rich solid energetic material guanidinium\n2-methyl-5-nitraminotetrazolate (G-MNAT). The ground state structural\nproperties calculated with dispersion corrected density functionals are in good\nagreement with experiment. The computed equilibrium crystal structure is\nfurther used to calculate the equation of state and zone-center vibrational\nfrequencies of the material. The electronic band structure is calculated and\nfound that the material is an indirect band gap semiconductor with a value of\n3.04 eV.",
        "positive": "Helium Ion Microscopy: Helium Ion Microcopy (HIM) based on Gas Field Ion Sources (GFIS) represents a\nnew ultra high resolution microscopy and nano-fabrication technique. It is an\nenabling technology that not only provides imagery of conducting as well as\nuncoated insulating nano-structures but also allows to create these features.\nThe latter can be achieved using resists or material removal due to sputtering.\nThe close to free-form sculpting of structures over several length scales has\nbeen made possible by the extension of the method to other gases such as Neon.\nA brief introduction of the underlying physics as well as a broad review of the\napplicability of the method is presented in this review."
    },
    {
        "anchor": "Empirical oscillating potentials for alloys from ab-initio fits and the\n  prediction of quasicrystal-related structures in the Al-Cu-Sc system: By fitting to a database of ab-initio forces and energies, we can extract\npair potentials for alloys, with a simple six-parameter analytic form including\nFriedel oscillations, which give a remarkably faithful account of many complex\nintermetallic compounds. Furthermore, such potentials are combined with a\nmethod of discovering complex zero-temperature structures with hundreds of\natoms per cell, given only the composition and the con- straint of known\nlattice parameters, using molecular-dynamics quenches. We apply this approach\nto structure prediction in the Al-Cu-Sc quasicrystal-related system.",
        "positive": "Thermal conductivity changes across a structural phase transition: the\n  case of high-pressure silica: By means of first-principles calculations, we investigate the thermal\nproperties of silica as it evolves, under hydrostatic compression, from a\nstishovite phase into a CaCl$_2$-type structure. We compute the thermal\nconductivity tensor by solving the linearized Boltzmann transport equation\niteratively in a wide temperature range, using for this the pressure-dependent\nharmonic and anharmonic interatomic couplings obtained from first principles.\nMost remarkably, we find that, at low temperatures, SiO$_2$ displays a large\npeak in the in-plane thermal conductivity and a highly anisotropic behavior\nclose to the structural transformation. We trace back the origin of these\nfeatures by analyzing the phonon contributions to the conductivity. We discuss\nthe implications of our results in the general context of continuous structural\ntransformations in solids, as well as the potential geological interest of our\nresults for silica."
    },
    {
        "anchor": "Acoustic phonon scattering in a low density, high mobility AlGaN/GaN\n  field effect transistor: We report on the temperature dependence of the mobility, $\\mu$, of the\ntwo-dimensional electron gas in a variable density AlGaN/GaN field effect\ntransistor, with carrier densities ranging from 0.4$\\times10^{12}$ cm$^{-2}$ to\n3.0$\\times10^{12}$ cm$^{-2}$ and a peak mobility of 80,000 cm$^{2}$/Vs. Between\n20 K and 50 K we observe a linear dependence $\\mu_{ac}^{-1} = \\alpha$T\nindicating that acoustic phonon scattering dominates the temperature dependence\nof the mobility, with $\\alpha$ being a monotonically increasing function of\ndecreasing 2D electron density. This behavior is contrary to predictions of\nscattering in a degenerate electron gas, but consistent with calculations which\naccount for thermal broadening and the temperature dependence of the electron\nscreening. Our data imply a deformation potential D = 12-15 eV.",
        "positive": "Grain Boundary Segregation Predicted by Quantum-Accurate Segregation\n  Spectra but not by Classical Models: In alloys, solute segregation at grain boundaries is classically attributed\nto three driving forces: a high solution enthalpy, a high size mismatch, and a\nhigh difference in interfacial energy. These effects are generally cast into a\nsingle scalar segregation energy and used to predict grain boundary solute\nenrichment or depletion. This approach neglects the physics of segregation at\nmany competing grain boundary sites, and can also miss electronic effects that\nare energetically significant to the problem. In this paper, we demonstrate\nthat such driving forces cannot explain, nor thus predict, segregation in some\nalloys. Using quantum-accurate segregation spectra that have recently become\navailable for some polycrystalline alloys, we predict strong segregation for\ngold in aluminum, a solvent-solute combination that does not conform to\nclassical driving forces. Our experiments confirm these predictions and reveal\ngold enrichment at grain boundaries that is two orders of magnitude over the\nbulk lattice solute concentration."
    },
    {
        "anchor": "Cage Electron-Hydroxyl Complex State as Electron Donor in Mayenite: It is inferred from the chemical shift of muon spin rotation ($\\mu$SR)\nspectra that muons implanted in pristine (fully oxidized) mayenite,\n[Ca$_{12}$Al$_{14}$O$_{32}]^{2+}$[$\\square_5$O$^{2-}$] (C12A7, with $\\square$\nreferring to the vacant cage), are bound to O$^{2-}$ at the cage center to form\nOMu$^-$ (where Mu represents muonium, a muonic analog of the H atom). However,\nan isolated negatively charged state (Mu$^-$, an analog of H$^-$) becomes\ndominant when the compound approaches the state of electride\n[Ca$_{12}$Al$_{14}$O$_{32}]^{2+}$[$\\square_4$2e$^{-}$] as a result of the\nreduction process. Moreover, the OMu$^-$ state in the pristine specimen\nexhibits depolarization of paramagnetic origin at low temperatures (below\n$\\sim$30~K), indicating that OMu$^-$ accompanies a loosely bound electron in\nthe cage that can be thermally activated. This suggests that interstitial muons\n(and hence H) forming a \"cage electron-hydroxyl\" complex can serve as electron\ndonors in C12A7.",
        "positive": "Unraveling effects of electron correlation in two-dimensional\n  Fe$_{n}$GeTe$_{2}$ (n=3, 4, 5) by dynamical mean field theory: The Fe$_{n}$GeTe$_{2}$ systems are newly discovered two-dimensional\nvan-der-Waals materials, exhibiting magnetism at room temperature. The\nsub-systems belonging to Fe$_{n}$GeTe$_{2}$ class are special because they show\nsite-dependent magnetic behavior. We focus on the critical evaluation of\nmagnetic properties and electron correlation effects in Fe$_{n}$GeTe$_{2}$\n($n$= 3, 4, 5) (FGT) systems performing first-principles calculations. Three\ndifferent ab-initio approaches have been used, viz., i) standard density\nfunctional theory (DFT), ii) incorporating static electron correlation (DFT+U)\nand iii) inclusion of dynamic electron correlation effect (DFT+DMFT). Our\nresults show that DFT+DMFT is the most accurate technique to correctly\nreproduce the magnetic interactions and experimentally observed transition\ntemperatures. The inaccurate values of structural parameters, magnetic moments\nand exchange interactions obtained from DFT+U make this method inapplicable for\nthe FGT family. Correct determination of magnetic properties for this class of\nmaterials is important since they are promising candidates for spin transport\nand spintronic applications at room temperature."
    },
    {
        "anchor": "Using Cluster Dynamics to Model Electrical Resistivity Measurements in\n  Precipitating Al-Sc Alloys: Electrical resistivity evolution during precipitation in Al-Sc alloys is\nmodeled using cluster dynamics. This mesoscopic modeling has already been shown\nto correctly predict the time evolution of the precipitate size distribution.\nIn this work, we show that it leads too to resistivity predictions in\nquantitative agreement with experimental data. We only assume that all clusters\ncontribute to the resistivity and that each cluster contribution is\nproportional to its area. One interesting result is that the resistivity excess\nobserved during coarsening mainly arises from large clusters and not really\nfrom the solid solution. As a consequence, one cannot assume that resistivity\nasymptotic behavior obeys a simple power law as predicted by LSW theory for the\nsolid solution supersaturation. This forbids any derivation of the precipitate\ninterface free energy or of the solute diffusion coefficient from resistivity\nexperimental data in a phase-separating system like Al-Sc supersaturated\nalloys.",
        "positive": "Prediction of entropy stabilized incommensurate phases in the system\n  MoS$_{2}$-MoTe$_{2}$: A first principles phase diagram calculation, that included van der Waals\ninteractions, was performed for the system\n(1-X)$\\cdot$MoS$_{2}$-(X)$\\cdot$MoTe$_{2}$. Surprisingly, the predicted phase\ndiagram has at least two ordered solid-solution phases, at $X \\approx 0.46$,\neven though all calculated formation energies are positive, in a ground-state\nanalysis that examined all configurations with 16 or fewer anion sites. The\nlower-temperature {\\bf $I$}-phase is predicted to transform to a\nhigher-temperature {\\bf $I^{\\prime}$}-phase at $T \\approx 500K$, and {\\bf\n$I^{\\prime}$} disorders at $T \\approx 730K$. Both these transitions are\npredicted to be first-order, and there are broad miscibility gaps on both sides\nof the ordered regions. Both the {\\bf $I$}- and {\\bf $I^{\\prime}$}-phases are\npredicted to be incommensurate: {\\bf $I$}-phase in three dimensions; and {\\bf\n$I^{\\prime}$}-phase in two dimensions."
    },
    {
        "anchor": "Structural and magnetic properties of Pr-alloyed MnBi nanostructures: The structural and magnetic properties of Pr-alloyed MnBi (short MnBi-Pr)\nnanostructures with a range of Pr concentrations have been investigated. The\nnanostructures include thin films having Pr concentrations 0, 2, 3, 5 and 9\natomic percent and melt-spun ribbons having Pr concentrations 0, 2, 4 and 6\npercent respectively. Addition of Pr into the MnBi lattice has produced a\nsignificant change in the magnetic properties of these nanostructures including\nan increase in coercivity and structural phase transition temperature, and a\ndecrease in saturation magnetization and anisotropy energy. The highest value\nof coercivity measured in the films is 23 kOe and in the ribbons is 5.6 kOe.\nThe observed magnetic properties are explained as the consequences of competing\nferromagnetic and antiferromagnetic interactions.",
        "positive": "Effect of Cr spacer on structural and magnetic properties of Fe/Gd\n  multilayers: In this work we analyse the role of a thin Cr spacer between Fe and Gd layers\non structure and magnetic properties of a [Fe(35A)/Cr(tCr)/Gd(50A)/Cr(tCr)]x12\nsuperlattice. Samples without the Cr spacer (tCr=0) and with a thin tCr=4A are\ninvestigated using X-ray diffraction, polarized neutron and resonance X-ray\nmagnetic reflectometry, SQUID magnetometery, magneto-optical Kerr effect and\nferromagnetic resonance techniques. Magnetic properties are studied\nexperimentally in a wide temperature range 4-300K and analysed theoretically\nusing numerical simulation on the basis of the mean-field model. We show that a\nreasonable agreement with the experimental data can be obtained considering\ntemperature dependence of the effective field parameter in gadolinium layers.\nThe analysis of the experimental data shows that besides a strong reduction of\nthe antiferromagnetic coupling between Fe and Gd, the introduction of Cr\nspacers into Fe/Gd superlattice leads to modification of both structural and\nmagnetic characteristics of the ferromagnetic layers."
    },
    {
        "anchor": "Redispersibility in magnetorheological fluids and its relevance for MRF\n  formulations: Very important research, with both theoretical and experimental results in\nthe advancement of physical models that explain the MR effect, try to keep the\nMRF formulation as simple as possible, usually with only two components: a\nmagnetic dispersed phase and a carrier liquid. Many patents of MRF include\nthree or four components, such as some surfactant and thixotropic additives. In\norder to formulate a good and reliable MRF for different applications such as\nMR shock absorbers, clutches, brakes, the MRF redispersibility is a challenge,\nbut mandatory, key property for out of lab real world applications. This\nchapter, we shows how to measure and evaluate the MRF redispersibility.",
        "positive": "Comparative Study of Covalent and van der Waals CdS Quantum Dot\n  Assemblies from Many-Body Perturbation Theory: Quantum dot (QD) assemblies are nanostructured networks made from aggregates\nof QDs and feature improved charge and energy transfer efficiencies compared to\ndiscrete QDs. Using first-principles many-body perturbation theory, we\nsystematically compare the electronic and optical properties of two types of\nCdS QD assemblies that have been experimentally investigated: QD gels, where\nindividual QDs are covalently connected via di- or poly-sulfide bonds, and QD\nnanocrystals, where individual QDs are bound via van der Waals interactions.\nOur work illustrates how the electronic, excitonic, and optical properties\nevolve when discrete QDs are assembled into 1D, 2D, and 3D gels and\nnanocrystals, as well as how the one-body and many-body interactions in these\nsystems impact the trends as the dimensionality of the assembly increases.\nFurthermore, our work reveals the crucial role of the covalent di- or\npoly-sulfide bonds in the localization of the excitons, which highlights the\ndifference between QD gels and QD nanocrystals."
    },
    {
        "anchor": "Renormalization of the Optical Response of Semiconductors by\n  Electron-Phonon Interaction: In the past five years enormous progress has been made in the ab initio\ncalculations of the optical response of electrons in semiconductors. The\ncalculations include the Coulomb interaction between the excited electron and\nthe hole left behind, as well as local field effects. However, they are\nperformed under the assumption that the atoms occupy fixed equilibrium\npositions and do not include effects of the interaction of the lattice\nvibrations with the electronic states (electron-phonon interaction). This\ninteraction shifts and broadens the energies at which structure in the optical\nspectra is observed, the corresponding shifts being of the order of the\naccuracy claimed for the ab initio calculations. These shifts and broadenings\ncan be calculated with various degrees of reliability using a number of\nsemiempirical and ab initio techniques, but no full calculations of the optical\nspectra including electron-phonon interaction are available to date.\n  This article discusses experimental and theoretical aspects of the\nrenormalization of optical response functions by electron-phonon interaction,\nincluding both temperature and isotopic mass effects. Some of the theoretical\ntechniques used can also be applied to analyze the renormalization of other\nresponse functions, such as the phonon spectral functions, the lattice\nparameters, and the elastic constants.",
        "positive": "High-throughput computational discovery of 40 ultralow thermal\n  conductivity and 20 highly anisotropic crystalline materials: We performed ab-initio driven density functional theory-based high throughput\ncomputations to search for materials with low thermal conductivity and high\nthermal transport anisotropy. We shortlisted a pool of 429 stable ternary\nsemiconductors from the Materials Project and obtained phonon thermal\nconductivity by solving the Boltzmann transport equation on 225 materials. We\nfound the lowest thermal conductivity of 0.16 W/m-K in SbRbK 2 and 40 materials\nwith a thermal conductivity lower than 1 W/m-K at 300 K. For anisotropic\nthermal transport, we have identified six materials with anisotropy larger than\n5 and 20 with thermal transport anisotropy higher than the largest reported\nliterature value."
    },
    {
        "anchor": "Proton irradiation effects on metal-YBCO interfaces: 10 MeV proton-irradiation effects on a YBCO-based test structure were\nanalyzed by measuring its current-voltage (IV) characteristics for different\ncumulated fluences. For fluences of up to $\\sim$80$\\cdot$10$^9$~p/cm$^2$ no\nchanges in the electrical behavior of the device were observed, while for a\nfluence of $\\sim$~300$\\cdot$10$^9~$ p/cm$^2$ it becomes less conducting. A\ndetailed analysis of the room temperature IV characteristics based on the\n$\\gamma$ power exponent parameter [$\\gamma=dLn(I)/dLn(V)$] allowed us to reveal\nthe main conduction mechanisms as well as to establish the equivalent circuit\nmodel of the device. The changes produced in the electrical behavior, in\naccordance with Monte Carlo TRIM simulations, suggest that the main effect\ninduced by protons is the displacement of oxygen atoms within the YBCO lattice,\nparticularly from oxygen-rich to oxygen-poor areas, where they become trapped.",
        "positive": "Steady State and Dynamics of Joule Heating in Magnetic Tunnel Junctions\n  Observed via the Temperature Dependence of RKKY Coupling: Understanding quantitatively the heating dynamics in magnetic tunnel\njunctions (MTJ) submitted to current pulses is very important in the context of\nspin-transfer-torque magnetic random access memory development. Here we provide\na method to probe the heating of MTJ using the RKKY coupling of a synthetic\nferrimagnetic storage layer as a thermal sensor. The temperature increase\nversus applied bias voltage is measured thanks to the decrease of the spin-flop\nfield with temperature. This method allows distinguishing spin transfer torque\n(STT) effects from the influence of temperature on the switching field. The\nheating dynamics is then studied in real-time by probing the conductance\nvariation due to spin-flop rotation during heating. This approach provides a\nnew method for measuring fast heating in spintronic devices, particularly\nmagnetic random access memory (MRAM) using thermally assisted or spin transfer\ntorque writing."
    },
    {
        "anchor": "Size scaling, dynamics, and electro-thermal bifurcation of VO2 Mott\n  oscillators: Traditional electronic devices are well-known to improve in speed and\nenergy-efficiency as their dimensions are reduced to the nanoscale. However,\nthis scaling behavior remains unclear for nonlinear dynamical circuit elements,\nsuch as Mott neuron-like spiking oscillators, which are of interest for\nbio-inspired computing. Here we show that shrinking micrometer-sized VO2\noscillators to sub-100 nm effective sizes, achieved using a nanogap cut in a\nmetallic carbon nanotube (CNT) electrode, does not guarantee faster spiking.\nHowever, an additional heat source such as Joule heating from the CNT, in\ncombination with small size and heat capacity (defined by the narrow volume of\nVO2 whose insulator-metal transition is triggered by the CNT), can increase the\nspiking frequency by ~1000x due to an electro-thermal bifurcation in the\nnonlinear dynamics. These results demonstrate that nonlinear dynamical switches\noperate in a complex phase space which can be controlled by careful\nelectro-thermal design, offering new tuning parameters for designing future\nbiomimetic electronics.",
        "positive": "Effective Temperature Dynamics in an Athermal Amorphous Plasticity\n  Theory: Recent developments in the theory of amorphous plasticity point to the\ncentral role played by the concept of an effective disorder temperature\n$T_{eff}$. An athermal dynamics for $T_{eff}$ are proposed in the framework of\na deformation theory and discussed in light of the recent steady state\nsimulations by Haxton and Liu [Phys. Rev. Lett. {\\bf 99}, 195701 (2007)]. The\nstructure of the resulting theory, its parameters and transient dynamics are\ndiscussed and compared to available data."
    },
    {
        "anchor": "Capacitance-Power-Hysteresis Trilemma in Nanoporous Supercapacitors: Nanoporous supercapacitors are an important player in the field of energy\nstorage that fill the gap between dielectric capacitors and batteries. The key\nchallenge in the development of supercapacitors is the perceived trade-off\nbetween capacitance and power delivery. Current efforts to boost the\ncapacitance of nanoporous supercapacitors focus on reducing the pore size so\nthat they can only accommodate a single layer of ions. However, this tight\npacking compromises the charging dynamics and hence power density. We show via\nan analytical theory and Monte Carlo simulations that charging is sensitively\ndependent on the affinity of ions to the pores, and that high capacitances can\nbe obtained for ionophobic pores of widths significantly larger than the ion\ndiameter. Our theory also predicts that charging can be hysteretic with a\nsignificant energy loss per cycle for intermediate ionophilicities. We use\nthese observations to explore the parameter regimes in which a\ncapacitance-power-hysteresis trilemma may be avoided.",
        "positive": "New allotropes of phosphorene with remarkable stability and intrinsic\n  piezoelectricity: In this letter, we show that a new class of two-dimensional phosphorus\nallotropes can be constructed via assembling the previously proposed ultrathin\nmetastable phosphorus nanotube into planar structures in different stacking\norientations. Based on first-principles method, the structures, stabilities and\nfundamental electronic properties of these new two-dimensional phosphorus\nallotropes are systematically investigated. These two-dimensional phosphorus\nallotropes possess remarkable stabilities due to the strong inter-tube van der\nWaals interactions, which cause an energy release of about 30-70 meV/atom\ndepending on their stacking manners. Our results show that most of these\ntwo-dimensional van der Waals phosphorene allotropes are energetically more\nfavorable than the experimentally viable black alpha-P and blue beta-P. Three\nof them showing relatively higher probability to be synthesized in future are\nfurther confirmed to be dynamically stable semiconductors with strain-tunable\nband gaps and remarkable piezoelectricity, which may have potential\napplications in nano-sized sensors, piezotronics, and energy harvesting in\nportable electronic nano-devices."
    },
    {
        "anchor": "Enhanced Li capacity in functionalized graphene: A first principle study\n  with van der Waals correction: We have investigated the adsorption of Li on graphene oxide using density\nfunctional theory. We show a novel and simple approach to achieve a positive\nlithiation potential on epoxy and hydroxyl functionalized graphene, compared to\nthe negative lithiation potential that has been found on prestine graphene. We\nincluded the van der Waals correction into the calculation so as to get better\npicture of weak interactions. A positive lithiation potential suggests a\nfavorable adsorption of Li on graphene oxide sheets that can lead to an\nincrease in the specific capacity, which in turn can be used as an anode\nmaterial in Li-batteries. We find a high specific capacity of ~860 mAh/g by\nfunctionalizing the graphene sheet. This capacity is higher than the previously\nreported capacities that were achieved on graphene with high concentration of\nStone-Wales (75%) and divacancy (16%) defects. Creating such high density of\ndefects can make the entire system energetically unstable, whereas graphene\noxide is a naturally occurring substance.",
        "positive": "One-dimensional van der Waals heterostructures as efficient metal-free\n  oxygen electrocatalysts: Two-dimensional covalent organic frameworks (2D-COFs) are an emerging family\nof catalytical materials with well-defined molecular structures. The stacking\nof 2D nanosheets and large intrinsic bandgaps significantly impair their\nperformance. Here, we report coaxial one-dimensional van der Waals\nheterostructures (1D vdWHs) comprised of a carbon nanotube (CNT) core and a\nthickness tunable thienothiophene-pyrene COF shell using a solution based in\nsitu wrapping method. Density functional theory calculations and in-operando\nand ex-situ spectroscopic analysis show that the carbon-sulfur region in the\nthienothiophene groups is the active catalytic site. The unique coaxial\nstructure enables controllable n-doping from the CNT core to the COF shell\ndepending on COF shell thickness, which lowers the bandgap and work function of\nCOF. Consequently, the charge transfer barrier between the active catalytic\nsite and adsorbed oxygen intermediates becomes lower, resulting in a dramatic\nenhancement in their catalytic activity for oxygen redox reactions. It enables\na high-performance rechargeable zinc-air battery with a specific capacity of\n696 mAh gZn-1 under a high current density of 40 mA cm-2 and excellent cycling\nstability. 1D vdWHs open the door to create multi-dimensional vdWHs for\nexploring fundamental physics and chemistry, as well as practical applications\nin electrochemistry, electronics, photonics, and beyond."
    },
    {
        "anchor": "Changes of Interatomic Force Constants Caused by Quantum Confinement\n  Effects: Study on the Calculations for the First-order Raman Spectrum of Si\n  Nanocrystals in Comparison with Experiments: The redshifts and asymmetric broadening observed in nanocrystal Raman Spectra\nare attributed to the quantum confinement effects by some authors. But others\nshow that they may come from the local heating caused by the incident laser as\nwell. In this study we demonstrate that in the Si nanocrystal case the latter\nat most has obvious effects on the broadening but has negligible effects on the\n1LO peak shift, while the former contributes most of the 1LO peak shift. We\nalso demonstrate that after assigning appropriate interatomic force constants\nin the calculation of Raman Spectrum by bond polarizability approximation model\nwithin the regime of free boundary condition, we may acquire the matching 1LO\npeak shift with experiments.",
        "positive": "Extent of stacking disorder in diamond: Hexagonal diamond has been predicted computationally to display extraordinary\nphysical properties including a hardness that exceeds cubic diamond. However, a\nrecent electron microscopy study has shown that so-called hexagonal diamond\nsamples are in fact not discrete materials but faulted and twinned cubic\ndiamond. We now provide a quantitative analysis of cubic and hexagonal stacking\nin diamond samples by analysing X-ray diffraction data with the DIFFaX software\npackage. The highest fractions of hexagonal stacking we find in materials which\nwere previously referred to as hexagonal diamond are below 60%. The remainder\nof the stacking sequences are cubic. We show that the cubic and hexagonal\nsequences are interlaced in a complex way and that naturally occurring\nLonsdaleite is not a simple phase mixture of cubic and hexagonal diamond.\nInstead, it is structurally best described as stacking disordered diamond. The\nfuture experimental challenge will be to prepare diamond samples beyond 60%\nhexagonality and towards the so far elusive 'perfect' hexagonal diamond."
    },
    {
        "anchor": "Long wavelength magnetic and magnetoelectric excitations in the\n  ferroelectric antiferromagnet BiFeO3: We present a terahertz spectroscopic study of magnetic excitations in\nferroelectric antiferromagnet BiFeO3. We interpret the observed spectrum of\nlong-wavelength magnetic resonance modes in terms of the normal modes of the\nmaterial's cycloidal antiferromagnetic structure. We find that the modulated\nDzyaloshinski-Moriya interaction leads to a splitting of the out-of-plane\nresonance modes. We also assign one of the observed absorption lines to an\nelectromagnon excitation that results from the magnetoelectric coupling between\nthe ferroelectric polarization and the cycloidal magnetic structure of BiFeO3.",
        "positive": "Electronic Structure and Optical Properties of Tin Iodide Solution\n  Complexes: The emerging interest in tin-halide perovskites demands a robust\nunderstanding of the fundamental properties of these materials starting from\nthe earliest steps of their synthesis. In a first-principles work based on\ntime-dependent density-functional theory, we investigate the structural,\nenergetic, electronic, and optical properties of 14 tin-iodide solution\ncomplexes formed by the SnI$_2$ unit tetracoordinated with molecules of common\nsolvents, which we classify according to their Gutmann's donor number. We find\nthat all considered complexes are energetically stable and their formation\nenergy expectedly increases with the donating ability of the solvent. The\nenergies of the frontier states are affected by the choice of the solvent with\ntheir absolute values decreasing with the donor number. The occupied orbitals\nare predominantly localized on the tin-iodide unit while the unoccupied ones\nare distributed also on the solvent molecules. Owing to this partial\nwave-function overlap, the first optical excitation is generally weak, although\nthe spectral weight is red-shifted by the solvent molecules being coordinated\nto SnI$_2$ in comparison to the reference obtained for this molecule alone.\nComparisons with results obtained on the same level of theory on Pb-based\ncounterparts corroborate our analysis. The outcomes of this study provide\nquantum-mechanical insight into the fundamental properties of tin-iodide\nsolution complexes. This knowledge is valuable in the research on lead-free\nhalide perovskites and their precursors."
    },
    {
        "anchor": "Hybrid Electron Spin Resonance and Whispering Gallery Mode Resonance\n  Spectroscopy of Fe3+ in Sapphire: The development of a new era of quantum devices requires an understanding of\nhow paramagnetic dopants or impurity spins behave in crystal hosts. Here, we\ndescribe a new spectroscopic technique which uses traditional Electron Spin\nResonance (ESR) combined with the measurement of a large population of\nelectromagnetic Whispering Gallery (WG) modes. This allows the characterization\nof the physical parameters of paramagnetic impurity ions in the crystal at low\ntemperatures. We present measurements of two ultra-high purity sapphires cooled\nto 20 mK in temperature, and determine the concentration of Fe3+ ions and their\nfrequency sensitivity to a DC magnetic field. Our method is different to ESR in\nthat it is possible to track the resonant frequency of the ion from zero\napplied magnetic field to any arbitrary value, allowing excellent measurement\nprecision. This high precision reveals anisotropic behaviour of the Zeeman\nsplitting, which has not been previously reported. In both crystals, each\nZeeman component demonstrates a different g-factor.",
        "positive": "Three-dimensional in situ characterization of phase transformation\n  induced austenite grain refinement in nickel-titanium: Near-field and far-field high-energy diffraction microscopy and microcomputed\ntomography X-ray techniques were used to study a bulk single crystal\nnickel-titanium shape memory alloy sample subjected to thermal cycling under a\nconstant applied load. Three-dimensional in situ reconstructions of the\naustenite microstructure are presented, including the structure and\ndistribution of emergent grain boundaries. After one cycle, the subgrain\nstructure is significantly refined, and heterogeneous {\\Sigma}3 and {\\Sigma}9\ngrain boundaries emerge. The low volume and uneven dispersion of the emergent\n{\\Sigma} boundaries across the volume show why previous transmission electron\nmicroscopy investigations of {\\Sigma} grain boundary formation were\ninconsistent."
    },
    {
        "anchor": "Energy storage in lead-free Ba(Zr, Ti)O$_{3}$ relaxor ferroelectrics:\n  Large densities and efficiencies and their origins: An atomistic first-principles-based effective Hamiltonian is used to\ninvestigate energy storage in Ba(Zr$_{0.5}$Ti$_{0.5}$)O$_{3}$ relaxor\nferroelectrics, both in their bulk and epitaxial films' forms, for electric\nfields applied along different crystallographic directions. We find that the\nenergy density linearly increases with temperature for electric fields applied\nalong the pseudocubic [001], [110] and [111] directions in\nBa(Zr$_{0.5}$Ti$_{0.5}$)O$_{3}$ bulk. For films at room temperature, the energy\ndensity adopts different behaviors (i.e., increase versus decrease) with strain\ndepending on the direction of the applied electric fields. We also predicted\nultrahigh energy densities (basically larger than 100 J/cm$^{3}$) with an ideal\nefficiency of 100\\% in all these Ba(Zr$_{0.5}$Ti$_{0.5}$)O$_{3}$ systems. In\naddition, a phenomenological model is used to reveal the origin of all the\naforementioned features, and should be applicable to other relaxor\nferroelectrics.",
        "positive": "Aligning tetracyanoplatinate thin films: By using a zone-casting derivative method it is possible to create\nwell-aligned 200 nm thin films of tetracyano platinate crystal wires, which\ncover more than 50% of the surface of the substrate. The aligned crystal wires\ndeviate only slightly from the casting direction and can each exceed 100 um in\nlength. Grazing incidence X-ray diffraction shows a 3.5 {\\AA} periodicity\ncorresponding to the intrachain Pt-Pt distance found in single crystals and a\n110 (crystal) orientation along the surface normal."
    },
    {
        "anchor": "GPU Acceleration of Large-Scale Full-Frequency GW Calculations: Many-body perturbation theory is a powerful method to simulate electronic\nexcitations in molecules and materials starting from the output of density\nfunctional theory calculations. By implementing the theory efficiently so as to\nrun at scale on the latest leadership high-performance computing systems it is\npossible to extend the scope of GW calculations. We present a GPU acceleration\nstudy of the full-frequency GW method as implemented in the WEST code.\nExcellent performance is achieved through the use of (i) optimized GPU\nlibraries, e.g., cuFFT and cuBLAS, (ii) a hierarchical parallelization strategy\nthat minimizes CPU-CPU, CPU-GPU, and GPU-GPU data transfer operations, (iii)\nnonblocking MPI communications that overlap with GPU computations, and (iv)\nmixed-precision in selected portions of the code. A series of performance\nbenchmarks have been carried out on leadership high-performance computing\nsystems, showing a substantial speedup of the GPU-accelerated version of WEST\nwith respect to its CPU version. Good strong and weak scaling is demonstrated\nusing up to 25920 GPUs. Finally, we showcase the capability of the GPU version\nof WEST for large-scale, full-frequency GW calculations of realistic systems,\ne.g., a nanostructure, an interface, and a defect, comprising up to 10368\nvalence electrons.",
        "positive": "Broken Symmetry, Boundary Conditions, and Band Gap Oscillations in\n  Finite Single Wall Nanotubes: We have shown how the interplay between the broken symmetry associated with\nthe finite single-wall nanotubes (SWNT) and the boundary conditions affects the\nelectronic properties of SWNTs in a profound way. For finite SWNTs (p,q)\ncharacterized by p=k+l,q=k-l,p-q=2l,l=0,1...,k, and k=1,2..., we found that the\nband gaps of finite SWNTs belonging to a certain k exhibit similar well-defined\noscillating patterns but with diminishing amplitudes from the armchair (l=0) to\nthe zigzag (l=k) SWNTs. These profound changes hold intiguing implications in\nthe potential utilization of these finite NTs as the basic component of\nmolecular scale devices."
    },
    {
        "anchor": "Plausible physical mechanisms for unusual volatile/non-volatile\n  resistive switching in HfO2-based stacks: Memristive devices made of silicon compatible simple oxides are of great\ninterest for storage and logic devices in future adaptable electronics and\nnon-digital computing applications. A series of highly desirable properties\nobserved in an atomic-layer-deposited hafnia-based stack, triggered our\ninterest to investigate their suitability for technological implementations. In\nthis paper, we report our attempts to reproduce the observed behaviour within\nthe framework of a proposed underlying mechanism. The inability of achieving\nthe electrical response of the original batch indicates that a key aspect in\nthose devices has remained undetected. By comparing newly made devices with the\noriginal ones, we gather some clues on the plausible alternative mechanisms\nthat could give rise to comparable electrical behaviours.",
        "positive": "Evidence for superferrimagnetic clusters and spin-glass transition\n  involving 4f Dy3+ spins in h-DyMnO3: A new twist to 4f Re3+ spin ordering in\n  hexagonal manganites: The ferroelectric phase of the multiferroic hexagonal manganites (h-ReMnO3)\nhas been reported to undergo a series of magnetic transitions involving\nlong-range ordering/reorientation of 4fRe3+ and/or 3dMn3+ spins below room\ntemperature. These transitions have attracted a lot of attention in recent\nyears due to the geometrically frustrated nature of magnetic interactions. We\nhave revisited these transitions in high quality single crystals of h-DyMnO3\nusing dc and ac susceptibility measurements as a function of temperature (T),\nmagnetic field (H) and frequency (w) supplemented by specific heat\nmeasurements. Taking h-DyMnO3 as an example, we show that the Dy3+ spins below\nTN~68K are in a superferrimagnetic (SFIM) state whereas they undergo spin-glass\n(SG) transition below TDy3+~7K. Our observations demonstrate that neither the\nN\\'eel transition at TN~68K nor the transition at TDy3+~7K is associated with\nlong-range ordered states of Dy3+ spins as believed so far in the literature.\nThe SG state of h-DyMnO3 is quite exotic as it occurs in an ordered compound\npurely due to geometrical frustration without any random disorder. Further, it\nshows an interesting crossover from de Almeida-Thouless type exponent (m=2/3)\nto Gabay-Toulouse type (m=2) with increasing field which cannot be explained in\nterms of the existing mean field theories of SG transition in Ising or\nHeisenberg systems but is expected for a vector X-Y SG system. Our observations\ncall for a systematic reinvestigation of the nature of magnetic transitions\ninvolving Re3+ ions in other h-ReMnO3 also."
    },
    {
        "anchor": "Multiferroic behavior of Aurivillius Bi4Mn3O12 from first-principles: The multiferroic behavior of the hypothetical Aurivillius compound Bi4Mn3O12\nhas been explored on the basis of density functional calculations. We find that\nthe tetragonal paraelectric phase of this material is ferromagnetic, showing\nferroelectric and antiferrodistortive instabilities similar to the ones\nobserved in its ferroelectric parent compound Bi4Ti3O12 . Our results indicate,\nhowever, that the presence of Mn+4 ions at the B-sites shrinks the cell volume\nand consequently the unstable polar mode, associated with the ferroelectric\npolarization, is overcame by an antiferrodistortive distortion. In this way,\nBi4Mn3O12 exhibits incipient ferroelectricity at its equilibrium volume. We\nshow that the ferroelectric state can be favored by strain or partial\nsubstitution of Mn with Ti.",
        "positive": "Erbium-based multifuncional compounds as molecular microkelvin-tunable\n  driving-sensing units: We demonstrate the selective control of the magnetic response and\nphotoluminescence properties of Er3+ centers with light, by associating them\nwith a highly conjugated beta-diketonate (1,3-di(2-naphthyl)-1,3-propanedione)\nligand. We demonstrate this system to be an optically-pumped molecular compound\nemittingin infra-red, which can be employed as a precise heat-driving and\ndetecting unit for low temperatures"
    },
    {
        "anchor": "Incoherent phonon transport dominates heat conduction across van der\n  Waals superlattices: Heat conduction mechanisms in superlattices could be different across\ndifferent types of interfaces. Van der Waals superlattices are structures\nphysically assembled through weak van der Waals interactions by design, and may\nhost properties beyond the traditional limits of lattice matching and\nprocessing compatibility, offering new types of interfaces. In this work,\nnatural van der Waals (SnS)1.17(NbS2)n superlattices are synthesized, and their\nthermal conductivities are measured by time-domain thermoreflectance as a\nfunction of interface density. Our results show that heat conduction of\n(SnS)1.17(NbS2)n superlattices is dominated by interface scattering when the\ncoherent length of phonons is larger than the superlattice period, indicating\nincoherent phonon transport dominates cross-plane heat conduction in van der\nWaals superlattices even when the period is atomically thin and abrupt.\nMoreover, our result suggests that the widely accepted heat conduction\nmechanism for conventional superlattices that coherent phonons dominate when\nthe period is short, is not applicable due to symmetry breaking in most van der\nWaals superlattices. Our findings provide new insight for understanding the\nthermal behavior of van der Waals superlattices, and devise approaches for\neffective thermal management of superlattices depending on the distinct types\nof interfaces.",
        "positive": "Binding energy and nature of the orbitals in fluorinated graphene: a\n  density functional theory study: We present density functional theory calculations of the binding energies of\none, two and three fluorine adatoms on the same side of monolayer graphene. We\nshow that fluorine dimers on graphene in a spin-singlet state are stable\nagainst dissociation into isolated fluorine adatoms, suggesting that there is a\ntendency for fluorine adatoms on a single side of graphene to cluster. Our\nresults suggest that fluorination develops by successive bonding of fluorine\natoms to neighbouring carbon atoms on different sublattices, while the spins\nare arranged to reduce the total magnetisation of the ground state. We find\nthat the finite-size error in the binding energy of a single fluorine atom or\ndimer on a periodic supercell of graphene scales inversely with the cube of the\nlinear size of the simulation supercell. By using $\\pi$-orbital axis analysis,\nthe rehybridisation of the three $\\sigma$-orbitals pointing directly along the\nbonds to the central fluorinated carbon is found to be\nsp\\textsuperscript{2.33}. The rehybridisation of the carbon orbital in the C--F\nbond is found to be sp\\textsuperscript{4.66}."
    },
    {
        "anchor": "Electronic and magnetic properties of low dimensional system Co2TeO3Cl2: The electronic and magnetic properties of transition metal oxyhalide compound\nCo2TeO3Cl2 is investigated using first principle calculations within the\nframework of density functional theory. In order to find underlying spin\nlattice of this compound, various hopping integrals and exchange interactions\nare calculated. The calculations reveal that the dominant inter-chain and\nintra-chain interactions are in ab plane. The exchange path is visualised by\nWannier function plotting. The nearest neighbour and next nearest neighbour\nexchange interactions are antiferromagnetic, making the system frustrated in\nlow dimension. The importance of spin orbit coupling in this compound is also\ninvestigated. The spin quantization axis is favoured along the crystallographic\nb direction.",
        "positive": "On the calculation of crystal field parameters using Wannier functions: We discuss the calculation of crystal field splittings using Wannier\nfunctions and show how the ligand field contributions can be separated from the\nbare Coulomb contribution to the crystal field by constructing sets of Wannier\nfunctions incorporating different levels of hybridization. We demonstrate this\nmethod using SrVO$_3$ as a generic example of a transition metal oxide. We then\ncalculate trends in the crystal field splitting for two series of hypothetical\ntetragonally distorted perovskite oxides and discuss the relation between the\ncalculated \"electro-static\" contribution to the crystal field and the simple\npoint charge model. Finally, we apply our method to the charge\ndisproportionated 5$d$ electron system CsAuCl$_3$. We show that the negative\ncharge transfer energy in this material leads to a reversal of the $p$-$d$\nligand contribution to the crystal field splitting such that the $e_g$ states\nof the nominally Au$^{3+}$ cation are energetically lower than the\ncorresponding $t_{2g}$ states."
    },
    {
        "anchor": "Direct observation of three-dimensional atomic structure of twinned\n  metallic nanoparticles and their catalytic properties: We determined a full 3D atomic structure of a dumbbell-shaped Pt nanoparticle\nformed by a coalescence of two nanoclusters using deep learning assisted atomic\nelectron tomography. Formation of double twin boundary was clearly observed at\nthe interface, while substantial anisotropy and disorder were also found\nthroughout the nanodumbbell. This suggests that the diffusion of interfacial\natoms mainly governed the coalescence process, but other dynamic processes such\nas surface restructuring and plastic deformation were also involved. A full 3D\nstrain tensor was clearly mapped, which allows direct calculation of the oxygen\nreduction reaction activity at the surface. Strong tensile strain was found at\nthe protruded region of the nanodumbbell, which results in an improved\ncatalytic activity on {100} facets. This work provides important clues\nregarding the coalescence mechanism and the relation between the atomic\nstructure and catalytic property at the single-atom level.",
        "positive": "Biaxial strain enhanced piezoelectric properties in monolayer\n  g-$\\mathrm{C_3N_4}$: Graphite-like carbon nitride (g-$\\mathrm{C_3N_4}$) is considered as a\npromising candidate for energy materials. In this work, the biaxial strain\n(-4\\%-4\\%) effects on piezoelectric properties of g-$\\mathrm{C_3N_4}$ monolayer\nare studied by density functional theory (DFT). It is found that the increasing\nstrain can reduce the elastic coefficient $C_{11}$-$C_{12}$, and increases\npiezoelectric stress coefficient $e_{11}$, which lead to the enhanced\npiezoelectric strain coefficient $d_{11}$. Compared to unstrained one, strain\nof 4\\% can raise the $d_{11}$ by about 330\\%. From -4\\% to 4\\%, strain can\ninduce the improved ionic contribution to $e_{11}$ of g-$\\mathrm{C_3N_4}$, and\nalmost unchanged electronic contribution, which is different from\n$\\mathrm{MoS_2}$ monolayer (the enhanced electronic contribution and reduced\nionic contribution). To prohibit current leakage, a piezoelectric material\nshould be a semiconductor, and g-$\\mathrm{C_3N_4}$ monolayer is always a\nsemiconductor in considered strain range. Calculated results show that the gap\nincreases from compressive strain to tensile one. At 4\\% strain, the first and\nsecond valence bands cross, which has important effect on transition dipole\nmoment (TDM). Our works provide a strategy to achieve enhanced piezoelectric\neffect of g-$\\mathrm{C_3N_4}$ monolayer, which gives a useful guidence for\ndeveloping efficient energy conversion devices."
    },
    {
        "anchor": "Z2-vortex order of frustrated Heisenberg antiferromagnets in two\n  dimensions: We discuss the recent experimental data on various frustrated\nquasi-two-dimensional Heisenberg antiferromagnets from the viewpoint of the\nZ2-vortex order, which include S=3/2 triangular-lattice antiferromagnet NaCrO2,\nS=1 triangular-lattice antiferromagnet NiGa2S4, S=1/2 organic\ntriangular-lattice antiferromagnets \\kappa-(BEDT-TTF)2Cu2(CN)3 and\nEtMe3Sb[Pd(dmit)2]2, and S=1/2 kagome-lattice antiferromagnet volborthite\nCu3V2O7(OH)22H2O, etc.",
        "positive": "Fast magnetization switching of Stoner particles: A nonlinear dynamics\n  picture: The magnetization reversal of Stoner particles is investigated from the point\nof view of nonlinear dynamics within the Landau-Lifshitz-Gilbert formulation.\nThe following results are obtained. 1) We clarify that the so-called\nStoner-Wohlfarth (SW) limit becomes exact when damping constant is infinitely\nlarge. Under the limit, the magnetization moves along the steepest energy\ndescent path. The minimal switching field is the one at which there is only one\nstable fixed point in the system. 2) For a given magnetic anisotropy, there is\na critical value for the damping constant, above which the minimal switching\nfield is the same as that of the SW-limit. 3) We illustrate how fixed points\nand their basins change under a field along different directions. This change\nexplains well why a non-parallel field gives a smaller minimal switching field\nand a short switching time. 4) The field of a ballistic magnetization reversal\nshould be along certain direction window in the presence of energy dissipation.\nThe width of the window depends on both of the damping constant and the\nmagnetic anisotropy. The upper and lower bounds of the direction window\nincrease with the damping constant. The window width oscillates with the\ndamping constant for a given magnetic anisotropy. It is zero for both zero and\ninfinite damping. Thus, the perpendicular field configuration widely employed\nin the current experiments is not the best one since the damping constant in a\nreal system is far from zero."
    },
    {
        "anchor": "Optical properties of graphene nanoribbons: the role of many-body\n  effects: We investigate from first principles the optoelectronic properties of\nnanometer-sized armchair graphene nanoribbons (GNRs). We show that many-body\neffects are essential to correctly describe both energy gaps and optical\nresponse. As a signature of the confined geometry, we observe strongly bound\nexcitons dominating the optical spectra, with a clear family dependent binding\nenergy. Our results demonstrate that GNRs constitute 1D nanostructures whose\nabsorption and luminescence performance can be controlled by changing both\nfamily and edge termination.",
        "positive": "Stability of xenon-sodium compounds at moderately low pressures: A growing body of theoretical and experimental evidence suggests that inert\ngases (He, Ne, Ar, Kr, Xe, Rn) become less and less inert under increasing\npressure. Here we use the ab initio evolutionary algorithm to predict stable\ncompounds of Xe and Na at pressures below 100 GPa, and find three stable\ncompounds, NaXe, NaXe$_3$ and NaXe$_4$. The NaXe belongs to a well-known cubic\nCsCl structure type. The NaXe$_4$'s structure is common in amphiboles, whereas\nthe NaXe$_3$ has a unique structure, analogous to the \"post-perovskite\"\northorhombic CaIrO$_3$-type structure with Ir atoms removed. This is the first\ntime that a cation-vacant version of the CaIrO$_3$ is found in any compound.\nNaXe, NaXe$_3$ and NaXe$_4$ are found to be metallic."
    },
    {
        "anchor": "Anti-site disorder and improved functionality of Mn$_{2}$Ni{\\it X} ({\\it\n  X}= Al, Ga, In, Sn) inverse Heusler alloys: Recent first-principles calculations have predicted Mn$_{2}$Ni{\\it X} ({\\it\nX}=Al, Ga, In, Sn) alloys to be magnetic shape memory alloys. Moreover,\nexperiments on Mn$_{2}$NiGa and Mn$_{2}$NiSn suggest that the alloys deviate\nfrom the perfect inverse Heusler arrangement and that there is chemical\ndisorder at the sublattices with tetrahedral symmetry. In this work, we\ninvestigate the effects of such chemical disorder on phase stabilities and\nmagnetic properties using first-principles electronic structure methods. We\nfind that except Mn$_{2}$NiAl, all other alloys show signatures of martensitic\ntransformations in presence of anti-site disorder at the sublattices with\ntetrahedral symmetry. This improves the possibilities of realizing martensitic\ntransformations at relatively low fields and the possibilities of obtaining\nsignificantly large inverse magneto-caloric effects, in comparison to perfect\ninverse Heusler arrangement of atoms. We analyze the origin of such\nimprovements in functional properties by investigating electronic structures\nand magnetic exchange interactions.",
        "positive": "Electron microscopy study of scratch-induced surface microstructures in\n  an Al-Cu-Fe icosahedral quasicrystal: Microstructure modifications induced by sliding a WC-Co indenter in scratch\ntests on the surface of a single phase AlCuFe icosahedral quasicrystal (IQC)\nwas studied by scanning electron microscopy (SEM) and transmission electron\nmicroscopy (TEM). The scratch track was shown tocomprise many smaller tracks.\nDislocations were discovered to emerge from the edges of the smaller scratch\ntracks. Along a small track where shear stress is concentrated, a phase\ntransition from IQC to a body-centered cubic (b.c.c.) phase with lattice\nparameter a=0.29 nm was pointed out. A modulated quasicrystal state as well as\na deformation twin of IQC were determined in the region beneath the scratch."
    },
    {
        "anchor": "Two-Dimensional Multiferroics: Ferroelasticity, Ferroelectricity, Domain\n  Wall, and Potential Mechano-Opto-Electronic Applications: Low-dimensional multiferroic materials hold great promises in miniaturized\ndevice applications such as nanoscale transducers, actuators, sensors,\nphotovoltaics, and nonvolatile memories. Here, using first-principles theory we\npredict that two-dimensional (2D) monolayer Group IV monochalcogenides\nincluding GeS, GeSe, SnS, and SnSe are a class of 2D semiconducting\nmultiferroics with strongly coupled giant in-plane spontaneous ferroelectric\npolarization and spontaneous ferroelastic lattice strain that are\nthermodynamically stable at room temperature and beyond, and can be effectively\nmodulated by elastic strain engineering. Their optical absorption spectra\nexhibit strong in-plane anisotropy with visible-spectrum excitonic gaps and\nsizable exciton binding energies, rendering the unique characteristics of\nlow-dimensional semiconductors. More importantly, the predicted low domain wall\nenergy and small migration barrier together with the coupled multiferroic order\nand anisotropic electronic structures suggest their great potentials for\ntunable multiferroic functional devices by manipulating external electrical,\nmechanical, and optical field to control the internal responses, and enable the\ndevelopment of four device concepts including 2D ferroelectric memory, 2D\nferroelastic memory, and 2D ferroelastoelectric nonvolatile photonic memory as\nwell as 2D ferroelectric excitonic photovoltaics.",
        "positive": "Competition between electron and phonon excitations in the scattering of\n  nitrogen atoms and molecules off tungsten and silver surfaces: We investigate the role played by electron-hole pair and phonon excitations\nin the interaction of reactive gas molecules and atoms with metal surfaces. We\npresent a theoretical framework that allows us to evaluate within a\nfull-dimensional dynamics the combined contribution of both excitation\nmechanisms while the gas particle-surface interaction is described by an\nab-initio potential energy surface. The model is applied to study energy\ndissipation in the scattering of N$_2$ on W(110) and N on Ag(111). Our results\nshow that phonon excitation is the dominant energy loss channel whereas\nelectron-hole pair excitations represent a minor contribution. We substantiate\nthat, even when the energy dissipated is quantitatively significant, important\naspects of the scattering dynamics are well captured by the adiabatic\napproximation."
    },
    {
        "anchor": "Monolayer, Bilayer and Heterostructures of Green Phosphorene for Water\n  Splitting and Photovoltaics: We report the results of density functional theory (DFT) based calculations\non monolayer and bilayer green phosphorene and their heterostructures with\nMoSe2. Both monolayer and bilayer green phosphorene are direct band gap\nsemiconductors and possess anisotropic carrier mobility as high as 10^{4}\ncm^{2}V^{-1}s^{-1}. In bilayers, pressure of about 9 GPa induces the\nsemiconductor-metal transition. Moreover, the band gap depends strongly on the\nthickness of the films and the external electric field. By employing\nstrain-engineering under suitable solution conditions, monolayer and AC-stacked\nbilayer green phosphorene offer the band edge alignments which can be used for\nwater splitting. The upper limit of the power conversion efficiencies for\nmonolayer, AB- and AC-stacked bilayer green phosphorene heterostructures with\nMoSe_{2} is calculated to be 18-21 %. Our results show the possibility of green\nphosphorene to be used as photocatalytic and photovoltaic material in the\nenergy-related applications.",
        "positive": "Excitons in epitaxially grown WS2 on Graphene: a nanometer-resolved EELS\n  and DFT study: In this study, we investigate excitonic properties of epitaxially grown WS2,\nwhich is of particular interest for various applications due to its potential\nfor upscaling to wafer sized structures. Understanding the effect of the\ndielectric environment due to changing layer numbers and multi-material\nheterostructures on the optical properties is crucial for tailoring device\nproperties. Monochromated electron energy loss spectroscopy in a scanning\ntransmission electron microscope is employed to characterize the excitonic\nspectrum of WS2 on graphene grown by metal organic chemical vapor deposition.\nThis technique provides the required spatial resolution at the nanometer scale\nin combination with high quality spectra. To complement the experimental\nresults, theoretical investigations using density functional theory and\napplying the Bethe-Salpeter equations are conducted. We find that by\ntransitioning from mono- to bi- to multilayers of WS2 the spectra show\nredshifts for both, the K-valley excitons at about 2.0 and 2.4 eV as well as\nexcitonic features of higher energies. The latter features originate from so\ncalled band nesting of transitions between the Gamma- and K-point. In summary,\nthis study provides valuable insights into the excitonic properties of WS2 in\ndifferent layer configurations and environments, which are realistically needed\nfor future device fabrication and property tuning. Finally, we can show that\nnanometer scale electron spectroscopy supported by careful theoretical\nmodelling can successfully link atomic structure and optical properties, such\nas exciton shifts, in non-idealized complex material systems like multilayer 2D\nheterostructures."
    },
    {
        "anchor": "Mesoscopic electronic heterogeneities in the transport properties of\n  V2O3 thin films: The spectacular metal-to-insulator transition of V2O3 can be progressively\nsuppressed in thin film samples. Evidence for phase separation was observed\nusing microbridges as a mesoscopic probe of transport properties where the same\nfilm possesses domains that exhibit a metal-to-insulator transition with clear\nfirst order features or remain metallic down to low temperatures. A simple\nmodel consisting of two parallel resistors can be used to quantify a phase\ncoexistence scenario explaining the measured macroscopic transport properties.\nThe interaction between film and substrate is the most plausible candidate to\nexplain this extended phase coexistence as shown by a correlation between the\ntransport properties and the structural data.",
        "positive": "On the origin of the electric carrier concentration in graphite: We investigate the dependence of the electrical resistivity of $\\sim 60 $nm\nthick single crystalline graphite samples on the defect concentration produced\nby proton irradiation at very low fluences. We show that the resistivity\ndecreases few percent at room temperature after inducing defects at\nconcentrations as low as $\\sim 0.1 $ppm due to the increase in the carrier\ndensity, in agreement with theoretical estimates. The overall results indicate\nthat the carrier densities measured in graphite are not intrinsic but related\nto defects and impurities."
    },
    {
        "anchor": "Remanence of Ni nanowire arrays: Influence of size and labyrinth\n  magnetic structure: The influence of the macroscopic size of the Ni nanowire array system on\ntheir remanence state has been investigated. A simple magnetic phenomenological\nmodel has been developed to obtain the remanence as a function of the\nmagnetostatic interactions in the array. We observe that, due to the long range\nof the dipolar interactions between the wires, the size of the sample strongly\ninfluence the remanence of the array. On the other hand, the magnetic state of\nnanowires has been studied by variable field magnetic force microscopy for\ndifferent remanent states. The distribution of nanowires with the magnetization\nin up or down directions and the subsequent remanent magnetization has been\ndeduced from the magnetic images. The existence of two short-range magnetic\norderings with similar energies can explain the typical labyrinth pattern\nobserved in magnetic force microscopy images of the nanowire arrays.",
        "positive": "Intertwining of magnetism and charge ordering in kagome FeGe: Recent experiments report a charge density wave (CDW) in the antiferromagnet\nFeGe, but the nature of the charge ordering and the associated structural\ndistortion remains elusive. We discuss the structural and electronic properties\nof FeGe. Our proposed ground state phase accurately captures atomic\ntopographies acquired by scanning tunneling microscopy. We show that the\n2$\\times$2$\\times$1 CDW likely results from the Fermi surface nesting of\nhexagonal-prism-shaped kagome states. FeGe is found to exhibit distortions in\nthe positions of the Ge atoms instead of the Fe atoms in the kagome layers.\nUsing in-depth first-principles calculations and analytical modeling, we\ndemonstrate that this unconventional distortion is driven by the intertwining\nof magnetic exchange coupling and CDW interactions in this kagome material.\nMovement of Ge atoms from their pristine positions also enhances the magnetic\nmoment of the Fe kagome layers. Our study indicates that magnetic kagome\nlattices provide a material candidate for exploring the effects of strong\nelectronic correlations on the ground state and their implications for\ntransport, magnetic, and optical responses in materials."
    },
    {
        "anchor": "Quasi 2-D magnetism in the Kagome layer compound FeSn: Single crystals of the single Kagome layer compound FeSn are investigated\nusing x-ray and neutron scattering, magnetic susceptibility and magnetization,\nheat capacity, resistivity, Hall, Seebeck, thermal expansion, thermal\nconductivity measurements and density functional theory (DFT). FeSn is a planar\nantiferromagnet below TN = 365 K and exhibits ferromagnetic magnetic order\nwithin each Kagome layer. The in-plane magnetic susceptibility is sensitive to\nsynthesis conditions. Resistivity, Hall and Seebeck results indicate multiple\nbands near the Fermi energy. The resistivity of FeSn is about 3 times lower for\ncurrent along the stacking direction than in the plane, suggesting that\ntransport and the bulk electronic structure of FeSn is not quasi 2D. FeSn is an\nexcellent metal with Rho(300K)/Rho(2K) values about 100 in both directions.\nWhile the ordered state is antiferromagnetic, high temperature susceptibility\nmeasurements indicate a ferromagnetic Curie-Weiss temperature of 173 K,\nreflecting the strong in-plane ferromagnetic interactions. DFT calculations\nshow a 3D electronic structure with the Dirac nodal lines along the K-H\ndirections in the magnetic Brillouin zone about 0.3 eV below the Fermi energy,\nwith the Dirac dispersions at the K points gapped by spin-orbit coupling except\nat the H point. The magnetism, however, is highly 2D with\nJin-plane/Jout-of-plane = 10. The predicted spin-wave spectrum is presented.",
        "positive": "Interfacial Thermal Conductance Spectrum in Nonequilibrium Molecular\n  Dynamics Simulations Considering Anharmonicity, Non-homogeneity and Quantum\n  Effects: Interfacial thermal transport is critical for many thermal-related\napplications such as heat dissipation in electronics. While the total\ninterfacial thermal conductance (ITC) can be easily measured or calculated, the\nITC spectral mapping has been investigated only recently and is not fully\nunderstood. By combining nonequilibrium molecular dynamics simulations and\natomistic Green's function method, we systematically investigate the ITC\nspectrum across an ideal interface, i.e., the argon-heavy argon interface. Our\nresults show that the ITC spectrum increases gradually with temperature as more\nphonons and anharmonic scattering channels are activated, e.g., the vibrations\nwith frequencies larger than 1 THz can contribute 5% (15%) to the total ITC at\n2 K (40 K) through anharmonic phonon scatterings channels. We further find that\nthe ITC spectrum from the left interfacial Hamiltonian is quite different from\nthat of the right interfacial Hamiltonian, which stems from the asymmetry of\nanharmonic phonon scatterings caused by the dissimilar vibrational property of\nthe two interfacial contacts. While all the phonons are involved in the\nanharmonic scatterings for the heavy argon interfacial Hamiltonian, these\nphonons involved in the anharmonic phonon scatterings from the argon\ninterfacial Hamiltonians are mainly these vibrations with frequency smaller\nthan 1 THz (i.e., the cut-off frequency of heavy argon). Finally, we find the\nquantum effect is important for the ITC spectrum at low temperatures, e.g.,\nbelow 30 K in our systems. Our results here systematically investigate the\ninfluence of anharmonicity, non-homogeneity, and quantum effects on the ITC\nspectrum, which is critical for designing and optimizing the interfaces with\nbetter performance."
    },
    {
        "anchor": "The influence of Structural Dynamics in Two-Dimensional Hybrid\n  Organic-Inorganic Perovskites on their Photoluminescence Efficiency --\n  Neutron scattering analysis: Two-dimensional hybrid organic-inorganic perovskites (HOIPs) have emerged as\npromising materials for light-emitting diode applications. In this study, by\nusing time-of-flight neutron spectroscopy we identified and quantitatively\nseparated the lattice vibrational and molecular rotational dynamics of two\nperovskites, butylammonium lead iodide $(\\text{BA})_{2}\\text{PbI}_{4}$ and\nphenethyl-ammonium lead iodide $\\text{(PEA)}_{2}\\text{PbI}_{4}$. By examining\nthe corresponding temperature dependence, we found that the lattice vibrations,\nas evidenced by neutron spectra, are consistent with the lattice dynamics\nobtained from Raman scattering. We revealed that the rotational dynamics of\norganic molecules in these materials tend to suppress their photoluminescence\nquantum yield while the vibrational dynamics did not show predominant\ncorrelations with their optoelectronic properties. This study proposes that the\nrotational motions of the polarized molecules could significantly interrupt the\nexciton binding energy potential, cause the exciton dissociations, enhance the\nnon-radiative recombination rates, and hence reduce the photoluminescence\nyield. These findings provide a deeper understanding of the fundamental\ninteractions in 2D HOIPs and may guide the design of more efficient\nlight-emitting materials for advanced technological applications.",
        "positive": "Determining the Curie temperature of La0.67Sr0.33MnO3 thin films: When comparing a set of La0.67Sr0.33MnO3 (LSMO) samples, the Curie\ntemperature (TC) of the samples is an important figure of merit for the sample\nquality. Therefore, a reliable method to determine TC is required. Here, a\nmethod based on the analysis of the magnetization loops is proposed."
    },
    {
        "anchor": "In situ compensation method for high-precision and high-sensitivity\n  integral magnetometry: An ongoing process of miniaturization of spintronics and magnetic-films-based\ndevices, as well as a growing necessity for basic material research place\nstringent requirements for sensitive and accurate magnetometric measurements of\nminute magnetic constituencies deposited on large magnetically responsive\ncarriers. However, the most popular multipurpose commercial superconducting\nquantum interference device (SQUID) magnetometers are not object-selective\nprobes, so the sought signal is usually buried in the magnetic response of the\ncarrier, contaminated by signals from the sample support, system instabilities\nand additionally degraded by an inadequate data reduction. In this report a\ncomprehensive method based on the in situ magnetic compensation for mitigating\nall these weak elements of SQUID-based magnetometry is presented. Practical\nsolutions and proper expressions to evaluate the final outcome of the\ninvestigations are given. Their universal form allows to employ the suggested\ndesign in investigations of a broad range of specimens of different sizes,\nshapes and compositions. The method does not require any extensive numerical\nmodelling, it relies only on the data taken from the standard magnetometer\noutput. The solution can be straightforwardly implemented in every field where\nmagnetic investigations are of a prime importance, including in particular\nemerging new fields of topological insulators, 3D-Dirac semimetals and\n2D-materials.",
        "positive": "Ternary eutectic dendrites: Pattern formation and scaling properties: Extending previous work [T. Pusztai, L. R\\'atkai, A. Sz\\'all\\'as, and L.\nGr\\'an\\'asy, Phys. Rev. E {\\bf 87}, 032402 (2013)], we have studied the\nformation of eutectic dendrites in a model ternary system within the framework\nof the phase-field theory. We have mapped out the domain in which two-phase\ndendritic structures grow. With increasing pulling velocity, the following\nsequence of growth morphologies is observed: flat front lamellae $\\rightarrow$\neutectic colonies $\\rightarrow$ eutectic dendrites $\\rightarrow$ dendrites with\ntarget pattern $\\rightarrow$ partitionless dendrites $\\rightarrow$\npartitionless flat front. We confirm that the two-phase and one-phase dendrites\nhave similar forms, and display a similar scaling of the dendrite tip radius\nwith the interface free energy. It is also found that the possible eutectic\npatterns include the target pattern, and single- and multiarm spirals, of which\nthe thermal fluctuations choose. The most probable number of spiral arms\nincreases with increasing tip radius and with decreasing kinetic anisotropy.\nOur numerical simulations confirm that in agreement with the assumptions of a\nrecent analysis of two-phase dendrites [S. Akamatsu, S. Bottin-Rousseau, G.\nFaivre, and E. A. Brener, Phys. Rev. Lett. {\\bf 112}, 105502 (2014)], the\nJackson-Hunt scaling of the eutectic wavelength with pulling velocity is obeyed\nin the parameter domain explored, and that the natural eutectic wavelength is\nproportional to the tip radius of the two-phase dendrites. Finally, we find\nthat it is very difficult/virtually impossible to form spiraling two-phase\ndendrites without anisotropy, an observation that seems to contradict the\nexpectations of Akamatsu {\\it et al.}. Yet, it cannot be excluded, that in\nisotropic systems two-phase dendrites are rare events difficult to observe in\nsimulations."
    },
    {
        "anchor": "Morphological evolution of edge-hillocks on single crystal films having\n  anisotropic drift-diffusion under the capillary and electromigration forces: The morphological evolution of hillocks at the unpassivated sidewalls of the\nsingle crystal metallic thin films is investigated via computer simulations by\nusing the free-moving boundary value problem. The effects of the\ndrift-diffusion anisotropy on the development of surface topographical\nscenarios is fully explored under the action of electromigration and capillary\nforces, utilizing numerous combination of the surface texture, the\ndrift-diffusion anisotropy and the direction of the applied electric field. The\npresent simulation studies yield very rich and technologically imported\ninformation, in regards to the critical texture of the single crystal thin film\nsurfaces, and the intensity and the orientation of the applied electric field,\nas far as the device reliability is concerned.",
        "positive": "Experimental study of extrinsic spin Hall effect in CuPt alloy: We have experimentally studied the effects on the spin Hall angle due to\nsystematic addition of Pt into the light metal Cu. We perform spin torque\nferromagnetic resonance measurements on Py/CuPt bilayer and find that as the Pt\nconcentration increases, the spin Hall angle of CuPt alloy increases. Moreover,\nonly 28% Pt in CuPt alloy can give rise to a spin Hall angle close to that of\nPt. We further extract the spin Hall resistivity of CuPt alloy for different Pt\nconcentrations and find that the contribution of skew scattering is larger for\nlower Pt concentrations, while the side-jump contribution is larger for higher\nPt concentrations. From technological perspective, since the CuPt alloy can\nsustain high processing temperatures and Cu is the most common metallization\nelement in the Si platform, it would be easier to integrate the CuPt alloy\nbased spintronic devices into existing Si fabrication technology."
    },
    {
        "anchor": "Regenerative Soot-VIII: Sputtering and formation of C1 and C2: Photoemission spectroscopy of the regenerative soot in neon's glow discharge\nplasma reveals the contributions from the sputtered atomic and molecular carbon\nspecies. We present the pattern of sputtering and the formation of monatomic C1\nand diatomic C2 as a function of the discharge current, the support gas\npressure and the number densities of the excited and ionized neon as the active\nconstituents of the carbonaceous plasma.",
        "positive": "Edge dislocation core structures in FCC metals determined from ab initio\n  calculations combined with the improved Peierls-Nabarro equation: We have employed the improved Peierls-Nabarro (P-N) equation to study the\nproperties of 1/2<110> edge dislocation in {111} plane in FCC metals Al, Cu,\nIr, Pd, and Pt. The generalized-stacking-fault energy (GSFE) surface entering\nthe equation is calculated by using first-principles density functional theory\n(DFT). The accuracy of the method has been tested by calculating values for\nvarious stacking fault energies which favorably compare with the previous\ntheoretical and experimental results. The core structures, including the core\nwidths both of the edge and screw components, dissociation behavior for edge\ndislocations have been investigated. The dissociated distance between two\npartials for Al in our calculation agrees well with the values obtained from\nthe numeric simulation with DFT and molecular dynamics simulation, as well as\nexperiment. Our calculations show that it is preferred to create partial\ndislocation in Cu, and to be easily observed full dislocation in Al, Ir, Pd,\nand especially Pt."
    },
    {
        "anchor": "Temperature dependent optical properties of $\\varepsilon$-Ga$_2$O$_3$\n  thin films: We determined the complex dielectric functions of $\\varepsilon$-Ga$_2$O$_3$\nusing optical transmittance and reflectance spectroscopies at temperatures from\n10 K to room temperature. The measured dielectric-function spectra reveal\ndistinct structures at a bandgap energy. We fitted a model dielectric function\nbased on the electronic energy-band structure to these experimental data. We\nanalyzed the temperature dependence of the band-gap with a model based on\nphonon dispersion effects. One could explain it in terms of phonon-related\nparameters such as the optical phonon temperature. We compare phonon-related\nproperties of $\\varepsilon$-Ga$_2$O$_3$ with those of a large variety of\nelement and binary semiconductors.",
        "positive": "Highly Efficient and Selective Extraction of Gold by Reduced Graphene\n  Oxide: Materials that are capable of extracting gold from complex sources,\nespecially electronic waste (e-waste) with high efficiency are needed for gold\nresource sustainability and effective e-waste recycling. However, it remains\nchallenging to achieve high extraction capacity to trace amount of gold, and\nprecise selectivity to gold over a wide range of complex co-existing elements.\nHere we report a reduced graphene oxide (rGO) material that has an ultrahigh\nextraction capacity for trace amounts of gold (1,850 mg/g and 1,180 mg/g to 10\nppm and 1 ppm gold). The excellent gold extraction behavior is accounted to the\ngraphene areas and oxidized regions of rGO. The graphene areas spontaneously\nreduce gold ions to metallic gold, and the oxidized regions provide a good\ndispersibility so that efficient adsorption and reduction of gold ions by the\ngraphene area can be realized. The rGO is also highly selective to gold ions.\nBy controlling the protonation process of the functional groups on the oxidized\nregions of rGO, it shows an exclusive gold extraction without adsorption of 14\nco-existing elements seen in e-waste. These discoveries are further exploited\nin highly efficient, continuous gold recycling from e-waste with good\nscalability and economic viability, as exemplified by extracting gold from\ne-waste using a rGO membrane based flow-through process."
    },
    {
        "anchor": "Corrosion Resistance of Sulfur-Selenium Alloy Coatings: Despite decades of research, metallic corrosion remains a long-standing\nchallenge in many engineering applications. Specifically, designing a material\nthat can resist corrosion both in abiotic as well as biotic environments\nremains elusive. Here we design a lightweight sulfur-selenium (S-Se) alloy with\nhigh stiffness and ductility that can serve as a universal corrosion-resistant\ncoating with protection efficiency of ~99.9% for steel in a wide range of\ndiverse environments. S-Se coated mild steel shows a corrosion rate that is 6-7\norders of magnitude lower than bare metal in abiotic (simulated seawater and\nsodium sulfate solution) and biotic (sulfate-reducing bacterial medium)\nenvironments. The coating is strongly adhesive and mechanically robust. We\nattribute the high corrosion resistance of the alloy in diverse environments to\nits semi-crystalline, non-porous, anti-microbial, and viscoelastic nature with\nsuperior mechanical performance, enabling it to successfully block a variety of\ndiffusing species.",
        "positive": "Interface identification of the solid electrolyte interphase on graphite: By means of Density Functional Theory calculations we evaluate several\nlithium carbonate - graphite interface models as a prototype of the Solid\nElectrolyte Interphase capping layer on graphite anodes in lithium-ion\nbatteries. It is found that only an (a,b)-oriented Li2CO3 slab promotes tight\nbinding with graphite. Such mutual organization of the components combines\ntheir structural features and reproduces coordination environment of ions,\nresulting in an adhesive energy of 116 meV/{\\AA}2 between graphite and lithium\ncarbonate. This model also presents a high potential affinity with bulk. The\ncorresponding charge distribution at such interface induces an electric\npotential gradient, such a gradient having been experimentally observed. We\nregard the mentioned criteria as the key descriptors of the interface stability\nand recommend them as the principal assessments for such interface study. In\naddition, we evaluate the impact of lithiated graphite on the stability of the\nmodel interface and study the generation of different point defects as\nmediators for Li interface transport. It is found that Li diffusion is mainly\nprovided by interstitials. The induced potential gradient fundamentally assists\nthe intercalation up to lithiation ratio of 70%."
    },
    {
        "anchor": "Phenomenological Model of Longitudinal Spin Fluctuations in Itinerant\n  Antiferromagnets: We present the phenomenological analysis of the spectrum of longitudinal spin\nfluctuations in isotropic itinerant electron antiferromagnets with account of\nspin anharmonicity giving rise to coupling of transverse and longitudinal\nnormal modes. The spectrum consists of a quasielastic part forming a central\npeak or a dip, depending on temperature and the Landau relaxation rate. Effects\nof spin fluctuation coupling also give rise to an inelastic part of the\nspectrum which has a form of resonances or antiresonances near the magnon\nfrequencies related to non-propagating longitudinal excitations.",
        "positive": "Crack-tip Plasticity and Intrinsic Toughening in Nano-sized Brittle\n  Amorphous Carbon: Most monolithic brittle materials are vulnerable to the failure by cracks\nbecause of a lack of intrinsic toughening mechanisms, such as the plasticity in\nthe vicinity of the crack front. As a result, most of the efforts to mitigate\nthe sudden failure of brittle ceramics have been focused on developing the\nextrinsic toughening mechanisms that hinder crack propagation behind the tip,\nsuch as the fiber bridging. In this work, we experimentally demonstrate that\nthe intrinsic toughening arises even in the brittle monolithic ceramic material\nsuch as diamond-like carbon (DLC) when its external dimension reduces down to\nsub-micron scales. This unique phenomenon owes its origin to the decrease of\nthe crack driving force in the small samples, which in turn enables them to\nbear high enough stresses to activate the local atomic plasticity. Through\nnanomechanical tensile and bending experiments, electron energy loss\nspectroscopy analysis, and finite element method for stress distribution\ncalculation, we confirmed that the local atomic plasticity associated with sp3\nto sp2 rehybridization is responsible for the intrinsic toughening."
    },
    {
        "anchor": "The Role of Oxygen at the Interface between Titanium and Carbon\n  Nanotubes: We study the interface between carbon nanotubes (CNTs) and surface-deposited\ntitanium using electron microscopy and photoemission spectroscopy, supported by\ndensity functional calculations. Charge transfer from the Ti atoms to the\nnanotube and carbide formation is observed at the interface which indicates\nstrong interaction. Nevertheless, the presence of oxygen between the Ti and the\nCNTs significantly weakens the Ti?CNT interaction. Ti atoms at the surface will\npreferentially bond to oxygenated sites. Potential sources of oxygen impurities\nare examined, namely oxygen from any residual atmosphere and pre-existing\noxygen impurities on the nanotube surface, which we enhance through oxygen\nplasma surface pretreatment. Variation in literature data concerning Ohmic\ncontacts between Ti and carbon nanotubes is explained via sample pre-treatment\nand differing vacuum levels, and we suggest improved treatment routes for\nreliable Schottky barrier-free Ti?nanotube contact formation.",
        "positive": "Infrared spectroscopy study of the nodal-line semimetal candidate ZrSiTe\n  under pressure: Hints for pressure-induced phase transitions: We studied the effect of external pressure on the optical response of the\nnodal-line semimetal candidate ZrSiTe by reflectivity measurements. At\npressures of a few GPa, the reflectivity, optical conductivity, and loss\nfunction are strongly affected in the whole measured frequency range (200-16500\ncm$^{-1}$), indicating drastic changes in the electronic band structure. The\npressure-induced shift of the electronic bands affects both the intraband and\ninterband transitions. We find anomalies in the pressure dependence of several\noptical parameters at the pressures $P_{c1}$$\\approx$4.1 GPa and\n$P_{c2}$$\\approx$6.5 GPa, suggesting the occurrence of two phase transitions of\neither structural or electronic type."
    },
    {
        "anchor": "Strongly anisotropic strain-tunability of excitons in exfoliated\n  ZrSe$_3$: We study the effect of uniaxial strain on the band structure of ZrSe$_3$, a\nsemiconducting material with a marked in-plane structural anisotropy. By using\na modified 3-point bending test apparatus, thin ZrSe$_3$ flakes were subjected\nto uniaxial strain along different crystalline orientations monitoring the\neffect of strain on their optical properties through micro-reflectance\nspectroscopy. The obtained spectra showed excitonic features that blueshift\nupon uniaxial tension. This shift is strongly dependent on the direction along\nwhich the strain is being applied. When the flakes are strained along the\nb-axis, the exciton peak shifts at ~ 60-95 meV/%, while along the a-axis, the\nshift only reaches ~ 0-15 meV/%. Ab initio calculations were conducted to study\nthe influence of uniaxial strain, applied along different crystal directions,\non the band structure and reflectance spectra of ZrSe$_3$, exhibiting a\nremarkable agreement with the experimental results.",
        "positive": "Dynamic Spin-Polarized Resonant Tunneling in Magnetic Tunnel Junctions: Precisely engineered tunnel junctions exhibit a long sought effect that\noccurs when the energy of the electron is comparable to the potential energy of\nthe tunneling barrier. The resistance of metal-insulator-metal tunnel junctions\noscillates with an applied voltage when electrons that tunnel directly into the\nbarrier's conduction band interfere upon reflection at the classical turning\npoints: the insulator-metal interface, and the dynamic point where the incident\nelectron energy equals the potential barrier inside the insulator. A model of\ntunneling between free electron bands using the exact solution of the\nSchroedinger equation for a trapezoidal tunnel barrier qualitatively agrees\nwith experiment."
    },
    {
        "anchor": "FeCuNbSiB thin films with sub-Oersted coercivity: Nanocrystalline FeCuNbSiB thin films were fabricated through magnetron\nsputtering followed by heat treatment, resulting in samples characterized by\nlow coercivity and high effective magnetization. Comprehensive microstructural\nanalysis, employing X-ray diffraction and transmission electron microscopy\ntechniques such as selected area electron diffraction, high-resolution imaging,\nand Fourier transform, was conducted. Magnetic properties were investigated\nusing an alternating gradient field magnetometer and broadband ferromagnetic\nresonance. The structural analysis revealed a well-defined microstructure of\nnanograins within an amorphous matrix in all of our films. However, the\ncoercivity of the 80 nm films did not exhibit as low values as observed for the\n160 nm films",
        "positive": "Detailed and high-throughput measurement of composition dependence of\n  magnetoresistance and spin-transfer torque using a composition-gradient film:\n  application to Co$_{x}$Fe$_{1-x}$ (0 $\\le$ $\\textit{x}$ $\\le$ 1) system: We develop a high-throughput method for measuring the composition dependence\nof magnetoresistance (MR) and spin-transfer-torque (STT) effects in\ncurrent-perpendicular-to-plane giant magnetoresistance (CPP-GMR) devices and\nreport its application to the CoFe system. The method is based on the use of\ncomposition-gradient films deposited by combinatorial sputtering. This\nstructure allows the fabrication of devices with different compositions on a\nsingle substrate, drastically enhancing the throughput in investigating\ncomposition dependence. We fabricated CPP-GMR devices on a single GMR film\nconsisting of a Co$_{x}$Fe$_{1-x}$ (0 $\\le$ $\\textit{x}$ $\\le$ 1)\ncomposition-gradient layer, a Cu spacer layer, and a NiFe layer. The MR ratio\nobtained from resistance-field measurements exhibited the maximum in the broad\nCo concentration range of 0.3 $\\le$ $\\textit{x}$ $\\le$ 0.65. In addition, the\nSTT efficiency was estimated from the current to induce magnetization reversal\nof the NiFe layer by spin injection from the Co$_{x}$Fe$_{1-x}$ layer. The STT\nefficiency was also the highest around the same Co concentration range as for\nthe MR ratio, and this correlation was theoretically explained by the change in\nthe spin polarization of the Co$_{x}$Fe$_{1-x}$ layer. The results revealed the\nCo$_{x}$Fe$_{1-x}$ composition range suitable for spintronic applications,\ndemonstrating the advantages of the developed method."
    },
    {
        "anchor": "Thin film TaAs: developing a platform for Weyl semimetal devices: MX monopnictide compounds (M=Nb,Ta, X = As,P) are prototypical\nthree-dimensional Weyl semimetals (WSMs) that have been shown in bulk single\ncrystal form to have potential for a wide variety of novel devices due to\ntopologically protected band structures and high mobilities. However, very\nlittle is known about thin film synthesis, which is essential to enable device\napplications. We synthesize TaAs(001) epilayers by molecular beam epitaxy on\nGaAs(001) and provide an experimental phase diagram illustrating conditions for\nsingle phase, single-crystal-like growth. We investigate the relationship\nbetween nanoscale defects and electronic structure, using angle-resolved\nphotoemission spectroscopy, Kelvin probe microscopy and transmission electron\nmicroscopy. Our results provide a roadmap and platform for developing 3D WSMs\nfor device applications.",
        "positive": "Spectra of Radiation Emitted from Open-Ended and Closed Carbon Nanotubes\n  Exposed to Microwave Fields: We performed experiments in which both open-ended and closed carbon nanotubes\nwere exposed to 2.46 GHz microwaves over the course of several irradiation and\ncooling cycles at a pressure of ~10-6 torr. The spectra of the radiation\nemitted from the nanotubes indicate that the intensity of the emitted radiation\nwith wavelengths of 650-1000 nm increased during the irradiation cycles.\nHowever, the intensity of the radiation emitted from untreated nanotubes\nincreased substantially more than the intensity of the radiation emitted from\nnanotubes that had been chemically treated in order to open nanotube ends. As\nopen-ended nanotubes have a lower work function than closed nanotubes, and as\nnanotube ends are known to open as they are heated, our results suggest that\nthe mechanism responsible for the emission of infrared, visible, and\nultra-violet radiation from carbon nanotubes exposed to microwaves is field\nemission-induced luminescence."
    },
    {
        "anchor": "Scaling the spin densities separately in density functional theory: Coordinate scaling of each spin density separately is considered in spin\ndensity functional theory. A virial theorem relates the spin-scaled correlation\nenergy to the spin-scaled correlation potentials. An adiabatic connection\nformula expresses energies at different spin interaction strengths in terms of\nspin scaling. Several popular approximate functionals are evaluated on the\nspin-scaled densities of atoms and of the uniform electron gas. The differences\nbetween this and uniform scaling are discussed.",
        "positive": "First-principles theory of intrinsic spin and orbital Hall and Nernst\n  effects in metallic monoatomic crystals: The generation of spin and orbital currents is of crucial importance in the\nfield of spin-orbitronics. In this work, using relativistic density functional\ntheory and the Kubo linear-response formalism, we systematically investigate\nthe spin Hall and orbital Hall effects for 40 monoatomic metals. The spin Hall\nconductivity (SHC) and orbital Hall conductivity (OHC) are computed as a\nfunction of the electrochemical potential and the influence of the spin-orbit\ninteraction strength is also investigated. Our calculations predict a rather\nsmall OHC in $sp$ metals, but a much larger OHC in $d$-band metals, with\nmaximum values [$\\sim 8000\\,(\\hbar/e)\\Omega^{-1}{\\rm cm}^{-1}$] near the middle\nof the $d$ series. Using the Mott formula, we evaluate the thermal counterparts\nof the spin and orbital Hall effects, the spin Nernst effect (SNE) and the\norbital Nernst effect (ONE). We find that the as-yet unobserved ONE is\nsignificantly larger ($\\sim 10 \\times$) than the SNE and has maximum values for\ngroup 10 elements (Ni, Pd, and Pt). Our work provides a broad overview of\nelectrically- and thermally-induced spin and orbital transport in monoatomic\nmetals."
    },
    {
        "anchor": "The general traits of inelastic electron scattering by the adsorbed\n  system: Inelastic electron scattering by the adsorbate covered Pt(100) single crystal\nsurface is studied by Disappearance Potential Spectroscopy and density of\nstates (DOS) calculations. Two peculiar channels of elastic electron\nconsumption are highlighted, both related to the substrate core level\nexcitation coupled separately with two particular electron transitions. The\nfirst channel affects the adsorbed layer and enables to reveal the valence\nstate structure of the adsorbed species as well as the substrate DOS. The\nsecond one includes the multiple plasmon oscillations. The proposed mechanism\nof electron transitions assumes that one-dimensional DOS at the vacuum level is\nan additional spot for location of excited electrons, along with vacant DOS at\nthe Fermi level. Observed phenomena are supposed to be a general regularity of\nelectron-solid interaction and a useful tool for fingerprinting the adsorbed\nlayer at molecular level.",
        "positive": "Alternative Stacking Sequences in Hexagonal Boron Nitride: The relative orientation of successive sheets, i.e. the stacking sequence, in\nlayered two-dimensional materials is central to the electronic, thermal, and\nmechanical properties of the material. Often different stacking sequences have\ncomparable cohesive energy, leading to alternative stable crystal structures.\nHere we theoretically and experimentally explore different stacking sequences\nin the van der Waals bonded material hexagonal boron nitride (h-BN). We examine\nthe total energy, electronic bandgap, and dielectric response tensor for five\ndistinct high symmetry stacking sequences for both bulk and bilayer forms of\nh-BN. Two sequences, the generally assumed AA' sequence and the relatively\nunknown (for h-BN) AB (Bernal) sequence, are predicted to have comparably low\nenergy. We present a scalable modified chemical vapor deposition method that\nproduces large flakes of virtually pure AB stacked h-BN; this new material\ncomplements the generally available AA' stacked h-BN."
    },
    {
        "anchor": "Phosphorene as a nanoelectromechanical material: Based on density functional simulations combined with the Landauer transport\ntheory, the mechanical strain impacts on the chemical bonds of phosphorene and\ntheir effects on the electronic properties are studied. Moreover, the effect of\nthe tensile strain along the zigzag direction on the charge transport\nproperties of a two-terminal phosphorene device is evaluated. Enhancement of\nthe intraplanar interactions, in particular between the next-nearest neighbors\nin strained phosphorene, is found to be essential in the band-structure\nevolution. The charge transport analyzing shows that phosphorene has a strong\npiezoconductance sensitivity, which makes this material highly desirable for\nhigh-pressure nanoelectromechanical applications. The piezoconductance gauge\nfactor increases by strain from 46 in 5% tension to 220 in 12% tension, which\nis comparable to state-of-the-art silicon strain sensors. The transmission\npathways monitor the current flowing in terms of the chemical bonds and\nhopping, however, the transport mostly arises from the charge transferring\nthrough the chemical bonds. The strong anisotropy in the transport properties\nalong zigzag and armchair directions is observed.",
        "positive": "Systematic investigation of emergent particles in type-III magnetic\n  space groups: In three-dimensional (3D) crystals, emergent particles arise when two or\nmultiple bands contact and form degeneracy (band crossing) in the Brillouin\nzone. Recently a complete classification of emergent particles in 3D\nnonmagnetic crystals, which described by the type-II magnetic space groups\n(MSGs), has been established. However, a systematic investigation of emergent\nparticles in magnetic crystals has not yet been performed, due to the\ncomplexity of the symmetries of magnetically ordered structures. Here, we\naddress this challenging task by exploring the possibilities of the emergent\nparticles in the 674 type-III MSGs. Based on effective k.p Hamiltonian and our\nclassification of emergent particles [Yu et al., Sci. Bull. 67, 375 (2022)\nDOI:10.1016/j.scib.2021.10.023], we identify all possible emergent particles,\nincluding spinful and spinless, essential and accidental particles in the\ntype-III MSGs. We find that all emergent particles in type-III MSGs also exist\nin type-II MSGs, with only one exception, i.e. the combined quadratic nodal\nline and nodal surface (QNL/NS). Moreover, tabulations of the emergent\nparticles in each of the 674 type-III MSGs, together with the symmetry\noperations, the small corepresentations, the effective k.p Hamiltonians, and\nthe topological character of these particles, are explicitly presented.\nRemarkably, combining this work and our homemade SpaceGroupIrep and MSGCorep\npackages will provide an effcient way to search topological magnetic materials\nwith novel quasiparticles."
    },
    {
        "anchor": "Role of precursor composition in the polymorph transformations,\n  morphology control and ferromagnetic properties of nanosized TiO$_2$: Pure phase and mixed phase TiO$_2$ nanoparticles have been produced using a\npyrolytic method from a non-aqueous carboxylate precursor. The precursor was\nprepared by a multiphase cation exchange using pentanoic acid (C$_4$H$_9$COOH).\nThe thermal stability, polymorph content, morphology, size distribution and\nsurface region of the produced nanoparticles were studied by TGA/DSC, XRD, FTIR\nand TEM. High quality monodisperse nanoparticles have been produced in the size\nrange from 7 to 27 nm. The nanoparticles showed room temperature ferromagnetism\nrevealed by VSM within bound polaron model. The carboxylate precursor is a good\nalternative to standard sol-gel to produce nanoparticles free from impurities.",
        "positive": "Time-Domain Studies of Very-Large-Angle Magnetization Dynamics Excited\n  by Spin Transfer Torques: We describe time-domain measurements which provide new information about the\nlarge-angle nonlinear dynamics of nanomagnets excited by spin-transfer torque\nfrom a spin-polarized current. Sampling-oscilloscope measurements, which\naverage over thousands of experimental time traces, show that the mean reversal\ntime for spin-transfer-driven magnetic switching has a step-like dependence on\nmagnetic field, because an integer number of precession cycles is required for\nreversal. Storage-oscilloscope measurements of individual experimental traces\nreveal non-periodic large-amplitude resistance variations at values of magnetic\nfield and current in a crossover region between the regimes of\nspin-transfer-driven switching and steady-state precession. We also observe\ndirectly the existence of time-dependent switching, on the nanosecond scale,\nbetween different precessional modes and between a precessional mode and a\nstatic state, at particular values of magnetic field and current bias."
    },
    {
        "anchor": "Structural and electronic changes of pentacene induced by potassium\n  doping: Potassium is introduced into the crystalline herringbone structure of\npentacene searching for a compound showing metallic electronic transport\nproperties and, hopefully, superconductivity at small enough temperatures.\nSeveral possible structures for stoichiometric KPentacene (1:1), K2Pentacene\n(2:1) and K3Pentacene (3:1) compounds are theoretically investigated. Detailed\ndensities of states for all of them are presented. As a more prominent result,\na new monoclinic structure has been stabilized for the potassium richer\nmaterial that could correspond to the recently synthesized superconducting\nphase of K3Pentacene. Although energetically unfavorable, it is the only\nmetallic candidate found to date.",
        "positive": "Nonlinear microscopic relaxation of uniform magnetization precession: Dynamic relaxation for nonlinear magnetization excitation is analyzed. For\ndirect processes, such as magnon-electron scattering and two-magnon scattering,\nthe relaxation rate is determined from the linear case simply by utilizing the\nmagnetization oscillation frequency for nonlinear excitation. For an indirect\nprocess, such as slow-relaxing impurities, the analysis gives an additional\nrelaxation term proportional to the excitation level. In all cases the\neffective magnetization damping is increased compared to\nLandau-Lifshitz-Gilbert damping."
    },
    {
        "anchor": "Surface structure of i-Al(68)Pd(23)Mn(9): An analysis based on the\n  T*(2F) tiling decorated by Bergman polytopes: A Fibonacci-like terrace structure along a 5fold axis of i-Al(68)Pd(23)Mn(9)\nmonograins has been observed by T.M. Schaub et al. with scanning tunnelling\nmicroscopy (STM). In the planes of the terraces they see patterns of dark\npentagonal holes. These holes are well oriented both within and among terraces.\nIn one of 11 planes Schaub et al. obtain the autocorrelation function of the\nhole pattern. We interpret these experimental findings in terms of the\nKatz-Gratias-de Boisseu-Elser model. Following the suggestion of Elser that the\nBergman clusters are the dominant motive of this model, we decorate the tiling\nT*(2F) by the Bergman polytopes only. The tiling T*(2F) allows us to use the\npowerful tools of the projection techniques. The Bergman polytopes can be\neasily replaced by the Mackay polytopes as the decoration objects. We derive a\npicture of ``geared'' layers of Bergman polytopes from the projection\ntechniques as well as from a huge patch. Under the assumption that no surface\nreconstruction takes place, this picture explains the Fibonacci-sequence of the\nstep heights as well as the related structure in the terraces qualitatively and\nto certain extent even quantitatively. Furthermore, this layer-picture requires\nthat the polytopes are cut in order to allow for the observed step heights. We\nconclude that Bergman or Mackay clusters have to be considered as geometric\nbuilding blocks of the i-AlPdMn structure rather than as energetically stable\nentities.",
        "positive": "Skyrmion Motion Driven by Oscillating Magnetic Field: Magnetic skyrmion motion induced by an electric current has drawn much\ninterest because of its application potential in next-generation magnetic\nmemory devices. Recently, unidirectional skyrmion motion driven by an\noscillating magnetic field was also demonstrated on large (20 micrometer)\nbubble domains with skyrmion topology. At smaller length scale which is more\nrelevant to high-density memory devices, we here show by numerical simulation\nthat a skyrmion of a few tens of nanometers could also be driven by\nhigh-frequency field oscillations but with the motion direction different from\nthe tilted oscillating field direction. We found that high-frequency field for\nsmall size skyrmions could excite skyrmion resonant modes and that a\ncombination of different modes would result in the final skyrmion motion with a\nhelical trajectory. Because this helical motion depends on the frequency of the\nfield, we can control both the speed and the direction of the skyrmion motion,\nwhich is a distinguishable characteristic compared with other methods."
    },
    {
        "anchor": "Nonreciprocal second harmonic generation in a magnetoelectric material: Nonreciprocal devices that allow the light propagation in only one direction\nare indispensable in photonic circuits and emerging quantum technologies.\nContemporary optical isolators and circulators, however, require large size or\nstrong magnetic fields because of the general weakness of magnetic light-matter\ninteractions, which hinders their integration into photonic circuits. Aiming at\nstronger magneto-optical couplings, a promising approach is to utilize\nnonlinear optical processes. Here, we demonstrate nonreciprocal magnetoelectric\nsecond harmonic generation (SHG) in CuB2O4. SHG transmission changes by almost\n100% in a magnetic-field reversal of just 10 mT. The observed nonreciprocity\nresults from an interference between the magnetic-dipole- and\nelectric-dipole-type SHG. Even though the former is usually notoriously smaller\nthan the latter, it is found that a resonantly enhanced\nmagnetic-dipole-transition has a comparable amplitude as non-resonant\nelectric-dipole-transition, leading to the near-perfect nonreciprocity. This\nmechanism could form one of the fundamental bases of nonreciprocity in\nmultiferroics, which is transferable to a plethora of magnetoelectric systems\nto realize future nonreciprocal and nonlinear-optical devices.",
        "positive": "Electrically tunable moir\u00e9 magnetism in twisted double bilayer\n  antiferromagnets: The introduction of moir\\'e superlattices to electronic materials can\ndramatically alter electronic properties, promising emergent correlated and\ntopological phenomena. Its first demonstration in van der Waals magnets\nexhibited noncollinear states and domain structures with, however, limited\nmanipulation. Here, we fabricated twisted double antiferromagnetic bilayer\nCrI3, and by magneto-optical Kerr effect microscopy demonstrate the coexistence\nof antiferromagnetic and ferromagnetic orders with nonzero net magnetization,\nwhich is the hallmark of moir\\'e magnetism. Such magnetic state exhibits\nnonmonotonic temperature dependence and extends over a wide range of twist\nangles with transitions at ~0{\\deg} and above 20{\\deg}. We further demonstrate\nvoltage-assisted magnetic switching and the linear magnetoelectric effect. The\nobserved nontrivial magnetic states and unprecedented control by twist angle,\ntemperature and electrical gating are supported by the simulated phase diagram\nof the moir\\'e magnetism. Our results illustrate the rich behaviors of twisted\nantiferromagnets and the control over them."
    },
    {
        "anchor": "Atomic and electronic structure transformations of silver nanoparticles\n  under rapid cooling conditions: The structural evolution and dynamics of silver nanodrops Ag${}_{2896}$ (4.4\nnm in diameter) during rapid cooling conditions has been studied by means of\nmolecular dynamics simulations and electronic density of state calculations.\nThe interaction of silver atoms is modeled by a tight-binding semiempirical\ninteratomic potential proposed by Cleri and Rosato. The pair correlation\nfunctions and the pair analysis technique is applied to reveal the structural\ntransition in the process of solidification. It is shown that Ag nanoparticles\nevolve into different nanostructures under different cooling processes. At a\ncooling rate of $1.5625\\times10^{13} Ks^{-1}$ the nanoparticles preserve an\namorphous like structure containing a large amount of 1551 and 1541 pairs which\ncorrespond to the icosahedral symmetry. For a lower cooling rate\n($1.5625\\times10^{12} Ks^{-1}$), the nanoparticles transform into a\ncrystal-like structure consisting mainly of 1421 and 1422 pairs which\ncorrespond to the fcc and hcp structures, respectively. The variations of the\nelectronic density of states for the differently cooled nanoparticles are small\nbut in correspondence with the structural changes.",
        "positive": "Intrinsic Half-Metallicity in Modified Graphene Nanoribbons: We perform first-principles calculations based on density functional theory\nto study quasi one-dimensional edge-passivated (with hydrogen) zigzag graphene\nnanoribbons (ZGNRs) of various widths with chemical dopants, boron and\nnitrogen, keeping the whole system isoelectronic. Gradual increase in doping\nconcentration takes the system finally to zigzag boron nitride nanoribbons\n(ZBNNRs). Our study reveals that, for all doping concentrations the systems\nstabilize in anti-ferromagnetic ground states. Doping concentrations and dopant\npositions regulate the electronic structure of the nanoribbons, exhibiting both\nsemiconducting and half-metallic behaviors as a response to the external\nelectric field. Interestingly, our results show that ZBNNRs with terminating\npolyacene unit exhibit half-metallicity irrespective of the ribbon width as\nwell as applied electric field, opening a huge possibility in spintronics\ndevice applications."
    },
    {
        "anchor": "Machine learning prediction of self-assembly and analysis of molecular\n  structure dependence on the critical packing parameter: Amphiphilic molecules spontaneously form self-assembly structures based on\nphysical conditions such as molecular structure, concentration, and\ntemperature. These structures exhibit various useful functions according to\ntheir morphology. The concept of the critical packing parameter serves to\ncorrelate self-organized structures with chemical composition. However, unless\nboth molecular arrangement and self-assembly patterns are understood, direct\ncomputational utilization for molecular design remains challenging. In this\nstudy, we attempt to predict the self-assembled structure of a molecule\ndirectly from its chemical structure and analyze factors influencing it using\nmachine learning. Dissipative particle dynamics simulations were used to\nreproduce many self-assembly structures composed of various chemical\nstructures, and their critical packing parameters were calculated. A machine\nlearning model was built using the chemical structures as input data and the\ncritical packing parameters as output data.As a result, both Random Forest and\na type of Recurrent Neural Network known as GRU demonstrated high predictive\naccuracy. It has been revealed through feature importance analysis and\ndependence on sample size that the amphiphilic nature of molecules\nsignificantly influences the self-assembly structures. Additionally, the\nimportance of selecting an appropriate molecular structure representation for\neach algorithm has been emphasized. The results of this research will help to\nfurther streamline product development in the fields of materials science,\nmaterials chemistry, and medical materials.",
        "positive": "Catalyst-free MBE growth of PbSnTe nanowires with tunable aspect ratio: Topological crystalline insulators (TCIs) are interesting for their\ntopological surface states, which hold great promise for scattering-free\ntransport channels and fault-tolerant quantum computing. A promising TCI is\nSnTe. However, Sn-vacancies form in SnTe, causing a high hole density,\nhindering topological transport from the surface being measured. This issue\ncould be relieved by using nanowires with a high surface-to-volume ratio.\nFurthermore, SnTe can be alloyed with Pb reducing the Sn-vacancies while\nmaintaining its topological phase. Here we present the catalyst-free growth of\nmonocrystalline PbSnTe in molecular beam epitaxy (MBE). By the addition of a\npre-deposition stage before the growth, we have control over the nucleation\nphase and thereby increase the nanowire yield. This facilitates tuning the\nnanowire aspect ratio by a factor of four by varying the growth parameters.\nThese results allow us to grow specific morphologies for future transport\nexperiments to probe the topological surface states in a Pb1-xSnxTe-based\nplatform."
    },
    {
        "anchor": "Correlation of Crystal Quality and Extreme Magnetoresistance of WTe$_2$: High quality single crystals of WTe$_2$ were grown using a Te flux followed\nby a cleaning step involving self-vapor transport. The method is reproducible\nand yields consistently higher quality single crystals than are typically\nobtained via halide assisted vapor transport methods. Magnetoresistance\n(MR)values at 9 Tesla and 2 Kelvin as high as 1.75 million \\%, nearly an order\nof magnitude higher than previously reported for this material, were obtained\non crystals with residual resistivity ratio (RRR) of approximately 1250. The MR\nfollows a near B$^2$ law (B = 1.95(1)) and, assuming a semiclassical model, the\naverage carrier mobility for the highest quality crystal was found to be\n~167,000 cm$^2$/Vs at 2 K. A correlation of RRR, MR ratio and average carrier\nmobility ($\\mu_{avg}$) is found with the cooling rate during the flux growth.",
        "positive": "New Buckled Honeycomb Lattice Compound Sr3CaOs2O9 Exhibiting\n  Antiferromagnetism above Room Temperature: Synthesis, crystal structure and magnetic properties of a new 2:1 ordered\ntriple perovskite Sr3CaOs2O9 are reported. The compound crystallizes in P21/c\nspace group and features a unique buckled honeycomb lattice of osmium. It\nexhibits long-range antiferromagnetic ordering with a high Neel temperature of\n385 K as confirmed by susceptibility, heat capacity and neutron diffraction\nmeasurements and is electrically insulating. This compound is also the first\nexample of a 2:1 ordered osmate perovskite. Theoretical investigations indicate\nthat Sr3CaOs2O9 features a sizeable antiferromagnetic exchange between the\npuckered planes resulting in a high TN. The magnetic properties of the known\ncompound Sr3CaRu2O9 are elucidated in comparison. It shows antiferromagnetic\norder below TN = 200 K."
    },
    {
        "anchor": "Distribution of dislocations in twisted bars: An asymptotically exact continuum dislocation theory of single crystal bars\nunder torsion is proposed. The dislocation distribution minimizing energy of\nthe bar with zero torque is shown to be uniform. If the applied torque is\nnon-zero, the minimizer exhibits a dislocation-free zone at the outer ring of\nthe bar's cross-section. The non-uniform distribution of dislocations in\nequilibrium as well as the twist angle per unit length are found in terms of\nthe given torque. With the energy dissipation being taken into account, there\nexists an elastic core region, while dislocation are concentrated in a ring\nbetween two dislocation-free zones. This leads to the change of the stress\ndistribution increasing the critical threshold of the torque.",
        "positive": "Evidence of hydrogen diffusion in n-type GaN: The control over impurities like hydrogen and oxygen is of key importance in\nnitride-based semiconducting due to their unrivaled applicability in\noptoelectronics and high power/high frequency electronics. Therefore, it is\ndesirable to continue the research on its diffusion and segregation in\nsemiconductor materials. In this work, we report on a first observation on\nhydrogen outdiffusion from bulk crystalline gallium nitride. The extent of the\nhydrogen diffusion is established by secondary ion mass spectrometry. Analysis\nof characteristic hydrogen profile in GaN grown using ammonothermal method, led\nto the determination of the hydrogen diffusion coefficient at the temperature\nof 1045C - a standard growth temperature for HVPE (halide vapor phase epitaxy)\nmethod."
    },
    {
        "anchor": "Bulk and Two-dimensional Silver and Copper Monohalides: A Unique Class\n  of Materials with Modest Ionicity/Covalency and\n  Ferroelasticity/Multiferroicity: Silver and copper monohalides can be viewed as a class of compounds in the\nneutral zone between predominantly covalent and ionic compounds, thereby\nexhibiting neither strong ionicity nor strong covalency. We show ab initio\ncalculation evidence that silver and copper monohalides entail relatively low\ntransition barriers between the non-polar rock-salt phase and the polar\nzinc-blende phase, due largely to their unique chemical nature of modest\niconicity or covalency. Notably, the low transition barriers endow both\nmonohalides with novel mechanical and electronic properties, i.e., coupled\nferroelasticity and ferroelectricity with large polarizations and relatively\nlow switching barriers at ambient conditions. Several halides even possess very\nsimilar lattice constants and structures as the prevailing semiconductors such\nas silicon, thereby enabling epitaxial growth on silicon. Moreover, based on\nextensive structural search, we find that the most stable two-dimensional (2D)\npolymorphs of the monolayer halides are close or even greater in energy than\ntheir bulk counterparts, a feature not usually seen in the family of rock-salt\nor zinc-blende semiconductors. The low transition barrier between zinc-blende\nphase and 2D phase is predicted. Moreover, several 2D monolayer halides also\nexhibit multiferroicity with coupled ferroelasticity or ferroelectricity,\nthereby rendering their potential applications as high-density integrated\nmemories for efficient data reading and writing. Their surfaces, covered by\nhalides, also provide oxidation resistance and give low cleave energy from\nlayered structure, suggesting high likelihood of experimental synthesis of\nthese 2D polymorphs.",
        "positive": "Nonmonotonic band gap evolution in bent phosphorene nanosheets: Nonmonotonic bending-induced changes of fundamental band gaps and\nquasiparticle energies are observed for realistic nanoscale phosphorene\nnanosheets. Calculations using stochastic many-body perturbation theory (sGW)\nshow that even slight curvature causes significant changes in the electronic\nproperties. For small bending radii (< 4 nm) the band-gap changes from direct\nto indirect. The response of phosphorene to deformation is strongly anisotropic\n(different for zig-zag vs. armchair bending) due to an interplay of exchange\nand correlation effects. Overall, our results show that fundamental band gaps\nof phosphorene sheets can be manipulated by as much as 0.7 eV depending on the\nbending direction."
    },
    {
        "anchor": "BAlGaN alloys nearly lattice-matched to AlN for efficient UV LEDs: The lattice mismatch between AlGaN and AlN substrates limits the design and\nefficiency of UV LEDs, but it can be mitigated by the co-incorporation of\nboron. We employ hybrid density functional theory to investigate the\nthermodynamic, structural, and electronic properties of BAlGaN alloys. We show\nthat BAlGaN can lattice match AlN with band gaps that match AlGaN of the same\ngallium content. We predict that BAlGaN emits transverse-electric polarized for\ngallium content of ~45% or more. Our results indicate that BAlGaN alloys are\npromising materials for higher efficiency UV optoelectronic devices on bulk AlN\nsubstrates.",
        "positive": "Carbon cage-like materials as potential low work function metallic\n  compounds: Case of clathrates: We present an ab-initio calculation of the electronic affinity of the\nhypothetical C-46 clathrate by studying its bare and hydrogenated (100)\nsurfaces. We show that such a system shares with the diamond phase a small\nelectronic affinity. Further, contrary to the diamond phase, the possibility of\ndoping endohedrally these cage-like systems allows to significantly raise the\nposition of the Fermi level, resulting in a true metal with a small work\nfunction. This is illustrated in the case of the Li8@C-46 doped compound. Such\na class of materials might be of much interest for the design of\nelectron-emitting devices."
    },
    {
        "anchor": "Morphological stability of electromigration-driven vacancy islands: The electromigration-induced shape evolution of two-dimensional vacancy\nislands on a crystal surface is studied using a continuum approach. We consider\nthe regime where mass transport is restricted to terrace diffusion in the\ninterior of the island. In the limit of fast attachment/detachment kinetics a\ncircle translating at constant velocity is a stationary solution of the\nproblem. In contrast to earlier work [O. Pierre-Louis and T.L. Einstein, Phys.\nRev. B 62, 13697 (2000)] we show that the circular solution remains linearly\nstable for arbitrarily large driving forces. The numerical solution of the full\nnonlinear problem nevertheless reveals a fingering instability at the trailing\nend of the island, which develops from finite amplitude perturbations and\neventually leads to pinch-off. Relaxing the condition of instantaneous\nattachment/detachment kinetics, we obtain non-circular elongated stationary\nshapes in an analytic approximation which compares favorably to the full\nnumerical solution.",
        "positive": "Renormalization of Molecular Quasiparticle Levels at Metal-Molecule\n  Interfaces: Trends Across Binding Regimes: When an electron or a hole is added into an orbital of an adsorbed molecule\nthe substrate electrons will rearrange in order to screen the added charge.\nThis results in a reduction of the electron addition/removal energies as\ncompared to the free molecule case. In this work we use a simple model to\nillustrate the universal trends of this renormalization mechanism as a function\nof the microscopic key parameters. Insight of both fundamental and practical\nimportance is obtained by comparing GW quasiparticle energies with Hartree-Fock\nand Kohn-Sham calculations. We identify two different polarization mechanisms:\n(i) polarization of the metal (image charge formation) and (ii) polarization of\nthe molecule via charge transfer across the interface. The importance of (i)\nand (ii) is found to increase with the metal density of states at the Fermi\nlevel and metal-molecule coupling strength, respectively."
    },
    {
        "anchor": "Intrinsic axion insulating behavior in antiferromagnetic\n  MnBi$_6$Te$_{10}$: A striking feature of time reversal symmetry (TRS) protected topological\ninsulators (TIs) is that they are characterized by a half integer quantum Hall\neffect on the boundary when the surface states are gapped by time reversal\nbreaking perturbations. While time reversal symmetry (TRS) protected TIs have\nbecome increasingly under control, magnetic analogs are still largely\nunexplored territories with novel rich structures. In particular, topological\nmagnetic insulators can also host a quantized axion term in the presence of\nlattice symmetries. Since these symmetries are naturally broken on the\nboundary, the surface states can develop a gap without external manipulation.\nIn this work, we combine theoretical analysis, density functional calculations\nand experimental evidence to reveal intrinsic axion insulating behavior in\nMnBi6Te10. The quantized axion term arises from the simplest possible mechanism\nin the antiferromagnetic regime where it is protected by inversion symmetry and\na fractional translation symmetry. The anticipated gapping of the Dirac surface\nstate at the edge is subsequently experimentally established using Angle\nResolved Spectroscopy. As a result, this system provides the magnetic analogue\nof the simplest TRS protected TI with a single, gapped Dirac cone at the\nsurface.",
        "positive": "Cryogenic Characteristics of Graphene Composites -- Evolution from\n  Thermal Conductors to Thermal Insulators: The development of cryogenic semiconductor electronics and superconducting\nquantum computing requires composite materials that can provide both thermal\nconduction and thermal insulation. We demonstrated that at cryogenic\ntemperatures, the thermal conductivity of graphene composites can be both\nhigher and lower than that of the reference pristine epoxy, depending on the\ngraphene filler loading and temperature. There exists a well-defined cross-over\ntemperature - above it, the thermal conductivity of composites increases with\nthe addition of graphene; below it, the thermal conductivity decreases with the\naddition of graphene. The counter-intuitive trend was explained by the\nspecificity of heat conduction at low temperatures: graphene fillers can serve\nas, both, the scattering centers for phonons in the matrix material and as the\nconduits of heat. We offer a physical model that explains the experimental\ntrends by the increasing effect of the thermal boundary resistance at cryogenic\ntemperatures and the anomalous thermal percolation threshold, which becomes\ntemperature dependent. The obtained results suggest the possibility of using\ngraphene composites for, both, removing the heat and thermally insulating\ncomponents at cryogenic temperatures - a capability important for quantum\ncomputing and cryogenically cooled conventional electronics."
    },
    {
        "anchor": "Magnetoresistance in Fe$_{1-x}$Ga$_x$ thin films presenting striped\n  magnetic pattern: the role of closure domains and domain walls: In this work we show the existence of closure domains in Fe$_{1-x}$Ga$_x$\nthin films featuring a striped magnetic pattern and study the effect of the\nmagnetic domain arrangement on the magnetotransport properties. By means of\nX-ray resonant magnetic scattering, we experimentally demonstrate the presence\nof such closure domains and estimate their sizes and relative contribution to\nsurface magnetization. Magnetotransport experiments show that the behavior of\nthe magnetoresistance depends on the measurement geometry as well as on the\ntemperature. When the electric current ows perpendicular to the stripe\ndirection, the resistivity decreases when a magnetic field is applied along the\nstripe direction (negative magnetoresistance) in all the studied temperature\nrange, and the calculations indicate that the main source is the anisotropic\nmagnetoresistance. In the case of current flowing parallel to the stripe\ndomains, the magnetoresistance changes sign, being positive at room temperature\nand negative at 100 K. To explain this behavior, the contribution to\nmagnetoresistance from the domain walls must be considered besides the\nanisotropic one.",
        "positive": "$GW$ vertex corrected calculations for molecular systems: Hedin's scheme is solved with the inclusion of the vertex function\n($GW\\Gamma$) for a set of small molecules.\n  The computational scheme allows for the consistent inclusion of the vertex\nboth at the polarizability level and in the self-energy.\n  A diagrammatic analysis shows that the self-energy formed with this\nfour-point vertex does not lead to double counting of diagrams, that can be\nclassified as direct \"bubbles\" and exchange diagrams.\n  By removing the exchange diagrams from the self-energy, a simpler\napproximation is obtained, called $GW^{\\rm{tc-tc}}$.\n  Very good agreement with expensive wavefunction-based methods is obtained for\nboth approximations."
    },
    {
        "anchor": "Magnetoelectric Effects in Ferromagnetic Metal-Piezoelectric Oxide\n  Layered Structures: Frequency dependence of magnetoelectric (ME) coupling is investigated in\ntrilayers of ferromagnetic alloy and piezoelectric lead zirconate titanate\n(PZT). The ferromagnetic phases studied include permendur, a soft magnet with\nhigh magnetostriction, iron, nickel, and cobalt. Low frequency data on ME\nvoltage coefficient versus bias magnetic field indicate strong coupling only\nfor trilayers with permendure or Ni. Measurements of frequency dependence of ME\nvoltage reveal a giant ME coupling at electromechanical resonance. The ME\ninteractions for transverse fields is an order of magnitude stronger than for\nlongitudinal fields. The maximum voltage coefficient of 90 V/cm Oe at resonance\nis measured for samples with nickel or permendure and is three orders of\nmagnitude higher than low-frequency values.",
        "positive": "Morphology of anisotropic chains in a magneto-rheological fluid during\n  aggregation and disaggregation processes: We study the morphology of the chain-like aggregates formed when a external\nconstant and uniaxial magnetic field is applied to a magneto-rheological (MR)\nfluid. In order to characterize the conformation of the aggregates, we study\nthe evolution of various fractal dimensions during aggregation and\ndisaggregation processes (i.e., when the applied field is switched on and off),\nusing video-microscopy and image analysis. Experiments have been performed by\nvarying the values of two external parameters: the magnetic field amplitude and\nparticle concentration. We found that the box-counting dimension, related with\nhow the aggregates occupy the surrounding space, depends on the ratio\n$R_1/R_0$. During the first stage of the disaggregation process, when the\nparticles are moving by Brownian motion inside the aggregate, Family-Vicsek\nscaling function is verified."
    },
    {
        "anchor": "Polarization-Engineering in III-V Nitride Heterostructures: New\n  Opportunities For Device Design: The role of spontaneous and piezoelectric polarization in III-V nitride\nheterostructure devices is discussed. Problems as well as opportunities in\nincorporating polarization in abrupt and graded heterojunctions composed of\nbinary, ternary, and quaternary nitrides are outlined.",
        "positive": "A Scheme to Classify Topological Property of Band Insulator Based On\n  One-band U(1) Chern Number: Topological insulator(TI) is a phase of matter discovered recently. Kane and\nMele proposed this phase is distinguished from the ordinary band insulator by a\nZ2 topological invariant.2 Several authors have try to related this Z2\ninvariant to Chern numbers. Roy find a way to calculate Z2 by Chern Number of\none of the two degenerate Bands or one-band Chern number(OBChN). However, he\ngive no concrete concrete proof of the equivalence of his Z2 and the Z2 in\nref[2] beside \\from the topological considerations of K theory\". So the\nimportance of OBChN hasn't been recognized by the community. In this letter we\nprove OBChN determines the Z2 in ref[2]. Then we illustrate OBChN is not only\nan useful tool to identify TI but also a natural criterion to classify\ntopological property of all time-reversal invariant band insulators. More\nimportantly we find a field in three dimensional TI can be identified with\nmagnetic field with magnetic monopole."
    },
    {
        "anchor": "Accurate electronic and optical properties of hexagonal germanium for\n  optoelectronic applications: High-quality defect-free lonsdaleite Si and Ge can now be grown on hexagonal\nnanowire substrates. These hexagonal phases of group-IV semiconductors have\nbeen predicted to exhibit improved electronic and optical properties for\noptoelectronic applications. While lonsdaleite Si is a well-characterized\nindirect semiconductor, experimental data and reliable calculations on\nlonsdaleite Ge are scarce and not consistent regarding the nature of its gap.\nUsing ab initio density-functional theory, we calculate accurate structural,\nelectronic, and optical properties for hexagonal Ge. Given the well-known\nsensitivity of electronic-structure calculations for Ge to the underlying\napproximations, we systematically test the performance of several\nexchange-correlation functionals, including meta-GGA and hybrid functionals. We\nfirst validate our approach for cubic Ge, obtaining atomic geometries and band\nstructures in excellent agreement with available experimental data. Then, the\nsame approach is applied to predict electronic and optical properties of\nlonsdaleite Ge. We portray lonsdaleite Ge as a direct semiconductor with only\nweakly dipole-active lowest optical transitions, small band gap, huge\ncrystal-field splitting, and strongly anisotropic effective masses. The\nunexpectedly small direct gap and the oscillator strengths of the lowest\noptical transitions are explained in terms of symmetry and back-folding of\nenergy bands of the diamond structure.",
        "positive": "Optical and magneto-optical properties of ferromagnetic full-Heusler\n  films: experiments and first-principles calculations: We report a joint theoretical and experimental study focused on understanding\nthe optical and magneto-optical properties of Co-based full-Heusler compounds.\nWe show that magneto-optical spectra calculated within ab-initio density\nfunctional theory are able to uniquely identify the features of the\nexperimental spectra in terms of spin resolved electronic transitions. As\nexpected for 3d-based magnets, we find that the largest Kerr rotation for these\nalloys is of the order of 0.3o in polar geometry. In addition, we demonstrate\nthat (i) multilayered structures have to be carefully handled in the\ntheoretical calculations in order to improve the agreement with experiments,\nand (ii) combined theoretical and experimental investigations constitute a\npowerful approach to designing new materials for magneto-optical and\nspin-related applications"
    },
    {
        "anchor": "General calculation of $4f-5d$ transition rates for rare-earth ions\n  using many-body perturbation theory: The $4f-5d$ transition rates for rare-earth ions in crystals can be\ncalculated with an effective transition operator acting between model $4f^N$\nand $4f^{N-1}5d$ states calculated with effective Hamiltonian, such as\nsemi-empirical crystal Hamiltonian. The difference of the effective transition\noperator from the original transition operator is the corrections due to mixing\nin transition initial and final states of excited configurations from both the\ncenter ion and the ligand ions. These corrections are calculated using\nmany-body perturbation theory. For free ions, there are important one-body and\ntwo-body corrections. The one-body correction is proportional to the original\nelectric dipole operator with magnitude of approximately 40% of the uncorrected\nelectric dipole moment. Its effect is equivalent to scaling down the radial\nintegral $\\ME {5d} r {4f}$, to about 60% of the uncorrected HF value. The\ntwo-body correction has magnitude of approximately 25% relative to the\nuncorrected electric dipole moment. For ions in crystals, there is an\nadditional one-body correction due to ligand polarization, whose magnitude is\nshown to be about 10% of the uncorrected electric dipole moment.",
        "positive": "Molecular dynamics simulation of melting of finite and inifinite size\n  graphene: We investigate the melting phenomena of pristine, free-standing infinite and\nfinite size graphene sheets via molecular dynamics simulation using AIREBO\npotential as implemented in the LAMMPS package. In our simulations, the\ntemperature of the systems under investigation are systematically heated up\nusing two independent heating protocols so that the resultant melting\ntemperatures from both schemes can be checked against each other for\nconsistency. The melting temperature of infinite graphene sheet is obtained by\nfollowing three independent computational experiments. In the first experiment,\nwe simulate the melting of various finite size graphenes, and then determine\nthe melting temperature of infinite graphene sheet as the temperature at which\nthe finite graphenes asymptotically grow in size. In the second experiment, we\nsimulate the melting of infinite single-wall carbon-nanotubes (SWCNTs) with\ndifferent radius, and then determine the melting temperature of infinite\ngraphene sheet as the temperature at which the radius of SWCNTs asymptotically\ngrows in size. In the third experiment, we heat up an infinite graphene that is\nformed by constructing a rectangular supercell which is subjected to periodic\nboundary condition at it sides. Melting temperature for infinite graphene\nobtained based on the first approach yields $\\sim$ 5799 K $\\pm$ 22 K. The\nsecond approach yield $\\sim$5302 K $\\pm$ 36 K, whereas $\\sim$5355 $\\pm$ 140 K\nfrom the third. There is an apparent disparity between the results from the\nfirst experiment and that of the second and third experiments due to\ndifferences in the technical details in these MD simulations. We cautiously\nconclude that, based on the consistency of the data of the second and third\nexperiments, that a free-standing infinite graphene sheet melts at the\ntemperature of 5302 K $\\pm$ 36 K, using AIREBO forcefield."
    },
    {
        "anchor": "Unified Framework for Dislocation-Based Defect Energetics: We present a unified framework for the calculation of defect energies for\nthose defects that can be represented as a superposition of isolated\ndislocations, and obtain both self and interaction energies of combinations of\ngrain boundaries and cracks. We recover in special limits several well known\nquantities such as the energy of a low-angle tilt boundary, as well as other\nlesser known results, including boundary/boundary and crack/boundary\ninteraction energies. This approach, in combination with simple dimensional\nanalysis, permits the rapid calculation of defect energetics in the elastic\nlimit.",
        "positive": "Van der Waals heterostructures: Research on graphene and other two-dimensional atomic crystals is intense and\nlikely to remain one of the hottest topics in condensed matter physics and\nmaterials science for many years. Looking beyond this field, isolated atomic\nplanes can also be reassembled into designer heterostructures made layer by\nlayer in a precisely chosen sequence. The first - already remarkably complex -\nsuch heterostructures (referred to as 'van der Waals') have recently been\nfabricated and investigated revealing unusual properties and new phenomena.\nHere we review this emerging research area and attempt to identify future\ndirections. With steady improvement in fabrication techniques, van der Waals\nheterostructures promise a new gold rush, rather than a graphene aftershock."
    },
    {
        "anchor": "Stacking Characteristics of Close Packed Materials: It is shown that the enthalpy of any close packed structure for a given\nelement can be characterised as a linear expansion in a set of continuous\nvariables $\\alpha_n$ which describe the stacking configuration. This enables us\nto represent the infinite, discrete set of stacking sequences within a finite,\ncontinuous space of the expansion parameters $H_n$. These $H_n$ determine the\nstable structure and vary continuously in the thermodynamic space of pressure,\ntemperature or composition. The continuity of both spaces means that only\ntransformations between stable structures adjacent in the $H_n$ space are\npossible, giving the model predictive and well as descriptive ability. We\ncalculate the $H_n$ using density functional theory and interatomic potentials\nfor a range of materials. Some striking results are found: e.g. the\nLennard-Jones potential model has 11 possible stable structures and over 50\nphase transitions as a function of cutoff range. The very different phase\ndiagrams of Sc, Tl, Y and the lanthanides are understood within a single\ntheory. We find that the widely-reported 9R-fcc transition is not allowed in\nequilibrium thermodynamics, and in cases where it has been reported in\nexperiments (Li, Na), we show that DFT theory is also unable to predict it.",
        "positive": "Momentum space anisotropy of electronic correlations in Fe and Ni - an\n  analysis of magnetic Compton profiles: The total and magnetically resolved Compton profiles are analyzed within the\ncombined density functional and dynamical mean field theory for the transition\nmetal elements Fe and Ni. A rather good agreement between the measured and\ncomputed magnetic Compton profiles (MCPs) of Fe and Ni is obtained with the\nstandard Local Spin Density Approximation (LSDA). By including local but\ndynamic many-body correlations captured by Dynamical Mean Field Theory (DMFT),\nthe calculated magnetic Compton profile is further improved when compared with\nexperiment. The second moment of the difference of the total Compton profiles\nbetween LSDA and DMFT, along the same momentum direction, has been used to\ndiscuss the strength of electronic correlations in Fe and Ni."
    },
    {
        "anchor": "Generative reconstruction of 3D volume elements for Ti-6Al-4V\n  basketweave microstructure by optimization of CNN-based microstructural\n  descriptors: We present a methodology for the generative reconstruction of 3D Volume\nElements (VE) for numerical multiscale analysis of Ti-6Al-4V processed by\nAdditive Manufacturing (AM). The basketweave morphology, which is typically\ndominant in AM-processed Ti-6Al-4V, is analyzed in conventional Electron\nBackscatter Diffusion (EBSD) micrographs. Prior \\b{eta}-grain reconstruction is\nperformed to obtain the out-of-plane orientation of the observed grains\nleveraging Burgers orientation relationship. Convolutional Neural Network (CNN)\n- based microstructure descriptors are extracted from the 2D data, and used for\ncross-section-based optimization of pixel values on orthogonal planes in 3D,\nusing the Microstructure Characterization and Reconstruction (MCR)\nimplementation MCRpy [16]. In order to utilize MCRpy, which performs best for\nbinary systems, the basketweave microstructure, which consists of up to twelve\ndistinct grain orientations, is decomposed into several separate two-phase\nsystems. Our reconstructions capture key characteristics of the titanium\nbasketweave morphology and show qualitative resemblance to experimentally\nobtained 3D data. The preservation of volume fraction during assembly of the\nreconstruction remains an unadressed challenge at this stage.",
        "positive": "Unraveling Bulk and Grain Boundary Electrical Properties in\n  La0.8Sr0.2Mn1-yO3 Thin Films: Grain boundaries in Sr-doped LaMnO3 thin films have been shown to strongly\ninfluence the electronic and oxygen mass transport properties, being able to\nprofoundly modify the nature of the material. The unique behaviour of the grain\nboundaries can be correlated with substantial modifications of the cation\nconcentration at the interfaces, which can be tuned by changing the overall\ncationic ratio in the films. In this work, we study the electronic properties\nof La0.8Sr0.2Mn1-yO3 thin films with variable Mn content. The influence of the\ncationic composition on the grain boundary and grain bulk electronic properties\nis elucidated by studying the manganese valence state evolution using\nspectroscopy techniques and by confronting the electronic properties of\nepitaxial and polycrystalline films. Substantial differences in the electronic\nconduction mechanism are found in the presence of grain boundaries and\ndepending on the manganese content. Moreover, the unique defect chemistry of\nthe nanomaterial is elucidated by measuring the electrical resistance of the\nthin films as a function of oxygen partial pressure, disclosing the importance\nof the cationic local non-stoichiometry on the thin films behavior."
    },
    {
        "anchor": "Surface acoustic wave devices on bulk ZnO at low temperature: Surface acoustic wave (SAW) devices based on thin films of ZnO are a well\nestablished technology. However, SAW devices on bulk ZnO crystals are not\npractical at room temperature due to the significant damping caused by finite\nelectrical conductivity of the crystal. Here, by operating at low temperatures,\nwe demonstrate effective SAW devices on the (0001) surface of bulk ZnO\ncrystals, including a delay line operating at SAW wavelengths of {\\lambda} = 4\nand 6 {\\mu}m and a one-port resonator at a wavelength of {\\lambda} = 1.6\n{\\mu}m. We find that the SAW velocity is temperature dependent, reaching $v\n\\simeq 2.68$ km/s at 10mK. Our resonator reaches a maximum quality factor of\n$Q_i \\simeq 1.5\\times 10^5$, demonstrating that bulk ZnO is highly viable for\nlow temperature SAW applications. The performance of the devices is strongly\ncorrelated with the bulk conductivity, which quenches SAW transmission above\nabout 200 K.",
        "positive": "Generation of dipole squeezing in a two-mode system with entangled\n  coherent states of a quantized electromagnetic field: Two-mode quantized electromagnetic fields can be entangled and admit a large\nnumber of coherent states. In this paper, we consider a two-mode system that\nconsists of a two-level atom interacting with a two-mode quantized\nelectromagnetic field, which is initially prepared in an entangled two-mode\ncoherent state, via a nondegenerate two-photon process in a lossless cavity. We\nstudy the quantum fluctuations in the two-mode system and investigate in detail\nthe effects of detuning, Stark shift and atomic coherence on atomic dipole\nsqueezing (ADS). We show that ADS strongly depends on the atomic coherence. It\nis found that the stronger the correlations between the two modes are involved,\nthe more the ADS could be generated. The detuning or Stark shift has a\ndestructive effect on ADS, but the combined effect of the detuning and Stark\nshift may lead to a regular, periodical and strong ADS pattern."
    },
    {
        "anchor": "Trends in bonding configuration at SiC/III-V semiconductor interfaces: The structural and electronic properties of interfaces between beta-SiC and\nIII-V semiconductors are studied by first-principles calculations. Favorable\nbonding configurations are found to form between Si-V and C-III (model A) for\nBN, AlN, AlP, AlAs, GaN, GaP, GaAs, InN, InP, InAs and InSb, and Si-III and C-V\n(model B) for BP, BAs, BSb, AlSb and GaSb. The relationship between formation\nenergy difference and lattice constant difference as well as charge\ndistribution for these two models is found. The origin of bonding\nconfigurations can be explained in terms of the ionicity of III-V\nsemiconductors, electrostatic effect, charge distribution and band-structure\ncomponent.",
        "positive": "Probabilistic Modeling of LCF Failure Times Using an Epidemiological\n  Crack Percolation Model: The analysis of standardized low cycle fatigue (LCF) experiments shows that\nthe failure times widely scatter. Furthermore, mechanical components often fail\nbefore the deterministic failure time is reached. A possibility to overcome\nthese problems is to consider probabilistic failure times. Our approach for\nprobabilistic life prediction is based on the microstructure of the metal.\nSince we focus on nickel-base alloys we consider a coarse grained\nmicrostructure, with random oriented FCC grains. This leads to random\ndistributed Schmid factors and different anisotropic stress in each grain. To\ngain crack initiation times, we use Coffin-Manson- Basquin and Ramberg-Osgood\nequation on stresses corrected with probabilistic Schmid factors.\n  Using these single grain crack initiation times, we have developed an\nepidemiological crack growth model over multiple grains. In this mesoscopic\ncrack percolation model, cracked grains induce a stress increase in neighboring\ngrains. This stress increase is realized using a machine learning model trained\non data generated from finite element simulations. The resulting crack clusters\nare evaluated with a failure criterion based on a multimodal stress intensity\nfactor. From the generated failure times, we calculate surface dependent hazard\nrates using a Monte Carlo framework. We compare the obtained failure time\ndistributions to data from LCF experiments and find good coincidence of\npredicted and measured scatter bands."
    },
    {
        "anchor": "Chemical Bonding Governs Complex Magnetism in MnPt5P: Subtle changes in chemical bonds may result in dramatic revolutions in\nmagnetic properties in solid state materials. MnPt5P, a new derivative of the\nrare-earth-free ferromagnetic MnPt5As, was discovered and is presented in this\nwork. MnPt5P was synthesized and its crystal structure and chemical composition\nwere characterized by X-ray diffraction as well as energy-dispersive X-ray\nspectroscopy. Accordingly, MnPt5P crystallizes in the layered tetragonal\nstructure with the space group P4/mmm (No. 123), in which the face-shared\nMn@Pt12 polyhedral layers are separated by P layers. In contrast to the\nferromagnetism observed in MnPt5As, the magnetic properties measurements on\nMnPt5P show antiferromagnetic ordering occurs at ~188 K with a strong magnetic\nanisotropy in and out of the ab-plane. Moreover, a spin-flop transition appears\nwhen a high magnetic field is applied. An A-type antiferromagnetic structure\nwas obtained from the analysis of powder neutron diffraction (PND) patterns\ncollected at 150 K and 9 K. Calculated electronic structures imply that\nhybridization of Mn-3d and Pt-5d orbitals are critical for both the structural\nstability and observed magnetic properties. Semi-empirical molecular orbitals\ncalculations on both MnPt5P and MnPt5As indicate that the lack of 4p character\non the P atoms at the highest occupied molecular orbital (HOMO) in MnPt5P may\ncause the different magnetic behavior in MnPt5P compared to MnPt5As. The\ndiscovery of MnPt5P, along with our previously reported MnPt5As, parametrizes\nthe end points of a tunable system to study the chemical bonding which tunes\nthe magnetic ordering from ferromagnetism to antiferromagnetism with strong\nspin-orbit coupling (SOC) effect.",
        "positive": "How chemical functionalization affects the lattice thermal\n  conductivities of antimony films?: Chemical functionalization is an effective means to tune electronic and\ncrystal structure of two-dimensional material, which may be crucial for moder\nmicroelectronics industry. Based on the first-principle calculation and an\niterative solution of Boltzmann transport equation, we find that antimony films\nare potential excellent thermoelectrical materials with rather low thermal\nconductivities $k$ ($<$ 2.5 W/mK). The chemical functionalization can induce\nthe reduction in $k$ to some extent, which is mainly due to the reduction of\nphonon lifetimes limited by the anharmonic scattering. More interesting, the\norigin of the reduction in $k$ is not the anharmonic interaction but the\nharmonic interaction from the depressed phonon spectrum mechanism, and for some\nchemical functional atom in halogen, the flat modes appearing in the low\nfrequency range play also a key factor in the reduction of $k$ by significantly\nincreasing the three-phonon scattering channels. Our work analyzes the\nreduction mechanism in $k$ from the chemical functionalization for antimonene,\nand provides a new view to adjust the thermal conductivity which can benefit\nthermoelectric material design."
    },
    {
        "anchor": "Shungite in view of neutron scattering: Recently suggested new concept of shungite (Int. J. Smart Nano Mat. DOI:\n10.1080/19475411.2014.885913) exhibits this carboneous raw material as a\nmulti-level fractal structure of nanosize fragments of reduced graphene oxide\n(rGO). In view of the extraordinary importance of the rGO starting material for\nthe current molecular graphene technology, the natural rGO deposits turns out\nto be quite challenging, making it highly necessary to prove the reliability of\nthe proposed rGO concept of shungite. Once consistent with all the block of the\navailable geological and physical-chemical data obtained during the last few\ndecades, the concept nonetheless needs a direct confirmation in terms of the\ncurrent graphene science. The first such acknowledgement has been received just\nrecently when studying photoluminescence (PL) of shungite dispersions\n(arXiv:1308.2569v2 [cond-mat.mes-hall]). A close similarity of PL spectra of\naqueous dispersion of shungite and those of synthetic graphene quantum dots of\nthe rGO origin has been established. The current paper presents the next direct\nconfirmation supplied with neutron scattering. Elastic neutron diffraction and\ninelastic neutron scattering have left no doubts concerning both graphene-like\nconfiguration and chemical composition of basic structural elements of shungite\nattributing the latter to rGO nanosize sheets with an average 11:1:3 (C:O:H)\natomic content ratio. The experimental data are supplemented with\nquantum-chemical calculations that allowed suggesting a clear vision of the\nshungite structure at its first nanolevels.",
        "positive": "Spin-lattice model for cubic crystals: We present a methodology based on the N\\'{e}el model to build a classical\nspin-lattice Hamiltonian for cubic crystals capable of describing magnetic\nproperties induced by the spin-orbit coupling like magnetocrystalline\nanisotropy and anisotropic magnetostriction, as well as exchange\nmagnetostriction. Taking advantage of the analytical solutions of the N\\'{e}el\nmodel, we derive theoretical expressions for the parameterization of the\nexchange integrals and N\\'{e}el dipole and quadrupole terms that link them to\nthe magnetic properties of the material. This approach allows to build accurate\nspin-lattice models with the desire magnetoelastic properties. We also explore\na possible way to model the volume dependence of magnetic moment based on the\nLandau energy. This new feature can allow to consider the effects of\nhydrostatic pressure on the saturation magnetization. We apply this method to\ndevelop a spin-lattice model for BCC Fe and FCC Ni, and we show that it\naccurately reproduces the experimental elastic tensor, magnetocrystalline\nanisotropy under pressure, anisotropic magnetostrictive coefficients, volume\nmagnetostriction and saturation magnetization under pressure at\nzero-temperature. This work could constitute a step towards large-scale\nmodeling of magnetoelastic phenomena."
    },
    {
        "anchor": "Novel Cross-Slip Mechanism of Pyramidal Screw Dislocations in Magnesium: Compared to cubic metals, whose primary slip mode includes twelve equivalent\nsystems, the lower crystalline symmetry of hexagonal close-packed metals\nresults in a reduced number of equivalent primary slips and anisotropy in\nplasticity, leading to brittleness at the ambient temperature. At higher\ntemperatures, the ductility of hexagonal close-packed metals improves owing to\nthe activation of secondary c+a pyramidal slip systems. Thus understanding the\nfundamental properties of corresponding dislocations is essential for the\nimprovement of ductility at the ambient temperature. Here, we present the\nresults of large-scale ab-initio calculations for c+a pyramidal screw\ndislocations in Mg and show that their slip behavior is a stark counterexample\nto the conventional wisdom that a slip plane is determined by the stacking\nfault plane of dislocations. A stacking fault between dissociated partial\ndislocations can assume a non-planar shape with a negligible energy cost and\ncan migrate normal to its plane by a local shuffling of atoms. Partial\ndislocations dissociated on a {2-1-12} plane \"slither\" in the {01-11} plane,\ndragging the stacking fault with them in response to an applied shear stress.\nThis finding resolves the apparent discrepancy that both {2-1-12} and {01-11}\nslip traces are observed in experiments while ab-initio calculations indicate\nthat dislocations preferably dissociate in the {01-11} planes.",
        "positive": "Electronic structure of overstretched DNA: Minuscule molecular forces can transform DNA into a structure that is\nelongated by more than half its original length. We demonstrate that this\npronounced conformational transition is of relevance to ongoing experimental\nand theoretical efforts to characterize the conducting properties of DNA wires.\nWe present quantum mechanical calculations for acidic, dry, poly(CG).poly(CG)\nDNA which has undergone elongation of up to 90 % relative to its natural\nlength, along with a method for visualizing the effects of stretching on the\nelectronic eigenstates. We find that overstretching leads to a drastic drop of\nthe hopping matrix elements between localized occupied electronic states\nsuggesting a dramatic decrease in the conductivity through holes."
    },
    {
        "anchor": "Spin Pumping from Permalloy into Uncompensated Antiferromagnetic Co\n  doped Zinc Oxide: Heterostructures of Co-doped ZnO and Permalloy were investigated for their\nstatic and dynamic magnetic interaction. The highly Co-doped ZnO is\nparamagentic at room temperature and becomes an uncompensated antiferromagnet\nat low temperatures, showing a narrowly opened hysteresis and a vertical\nexchange bias shift even in the absence of any ferromagnetic layer. At low\ntemperatures in combination with Permalloy an exchange bias is found causing a\nhorizontal as well as vertical shift of the hysteresis of the heterostructure\ntogether with an increase in coercive field. Furthermore, an increase in the\nGilbert damping parameter at room temperature was found by multifrequency FMR\nevidencing spin pumping. Temperature dependent FMR shows a maximum in magnetic\ndamping close to the magnetic phase transition. These measurements also\nevidence the exchange bias interaction of Permalloy and long-range ordered\nCo-O-Co structures in ZnO, that are barely detectable by SQUID due to the\nshorter probing times in FMR.",
        "positive": "Ultrafast spin-to-charge conversions of antiferromagnetic (111)-oriented\n  $\\mathrm{L1_2}$-$\\mathrm{Mn_3Ir}$: Antiferromagnetic $\\mathrm{L1_2}$-$\\mathrm{Mn_3Ir}$ combines outstanding\nspin-transport properties with magnons in the terahertz (THz) frequency range.\nHowever, the THz radiation emitted by ultrafast spin-to-charge conversion via\nthe inverse spin Hall effect remains unexplored. In this study, we measured the\nTHz emission and transmission of a permalloy/(111)-oriented\n$\\mathrm{L1_2}$-$\\mathrm{Mn_3Ir}$ multilayer by THz time-domain spectroscopy.\nThe spin Hall angle was determined to be approximately constant at 0.035 within\na frequency range of 0.3-2.2 THz, in comparison with the THz spectroscopy of a\npermalloy/Pt multilayer. Our results not only demonstrate the potential of\n$\\mathrm{L1_2}$-$\\mathrm{Mn_3Ir}$ as a spintronic THz emitter but also provide\ninsights into the THz spin transport properties of\n$\\mathrm{L1_2}$-$\\mathrm{Mn_3Ir}$."
    },
    {
        "anchor": "Strain, Young's modulus, and structural transition of EuTiO3 thin films\n  probed by micro-mechanical methods: EuTiO3 (ETO) is a well-known complex oxide mainly investigated for its\nmagnetic properties and its incipient ferro-electricity. In this work, we\ndemonstrate the realization of suspended micro-mechanical structures, such as\ncantilevers and micro-bridges, from 100 nm-thick single-crystal epitaxial ETO\nfilms deposited on top of SrTiO3(100) substrates. By combining profile analysis\nand resonance frequency measurements of these devices, we obtain the Young's\nmodulus, strain, and strain gradients of the ETO thin films. Moreover, we\ninvestigate the ETO anti-ferro-distorsive transition by temperature-dependent\ncharacterizations, which show a non-monotonic and hysteretic mechanical\nresponse. Comparison between experimental and literature data allows us to\nweight the contribution from thermal expansion and softening to the tuning\nslope, while a full understanding of the origin of such a wide hysteresis is\nstill missing. We also discuss the influence of oxygen vacancies on the\nreported mechanical properties by comparing stoichiometric and oxygen-deficient\nsamples.",
        "positive": "Total transmission and total reflection of acoustic wave by zero index\n  metamaterials loaded with general solid defects: This work investigates acoustic wave transmission property through a zero\nindex metamaterials (ZIM) waveguide embedded with a general solid defect. Total\ntransmission and total reflection can be achieved by adjusting the parameters\nof the solid defect. We comprehensively study how longitudinal/transverse wave\nspeeds of the solid defect affect the acoustic wave propagation through the\nwaveguide. A two-dimensional (2D) acoustic crystals (ACs) system with zero\nindex is used to realize these intriguing transmission properties. Thus, our\nwork provides more possibilities to manipulate acoustic wave propagation\nthrough ZIM."
    },
    {
        "anchor": "Discrimination and analysis of interactions in non-contact Scanning\n  Force Microscopy: A method for the separation and quantitative characterization of the\nelectrostatic and Van der Waals contribution to tip-sample interaction in\nnon-contact Scanning Force Microscopy is presented. It is based on the\nsimultaneous measurement of cantilever deflection, oscillation amplitude and\nfrequency shift as a function of tip-sample voltage and tip-sample distance as\nwell as on advanced data processing. Data is acquired at a fixed lateral\nposition as interaction images with the bias voltage as fast scan and\ntip-sample distance as slow scan. Due to the quadratic dependence of the\nelectrostatic interaction with tip-sample voltage the Van der Waals force can\nbe separated from the electrostatic force. Using appropriate data-processing\nthe Van der Waals interaction, the capacitance as well as the contact potential\ncan be determined as a function of tip-sample distance from the force as well\nas from the frequency shift data. The measurement of resonance frequency shift\nyields very high signal to noise ratio and the absolute calibration of the\nmeasured quantities, while the acquisition of cantilever deflection allows the\ndetermination of tip-sample distance. The separation and quantitative analysis\nof Van der Waals and electrostatic interaction as proposed in the present work\nresults in precise and reproducible measurement of tip-sample interaction that\nwill significantly improve the interpretation of SFM data and will\nsubstantially contribute to the characterization of nanoscale properties by\nSFM.",
        "positive": "Electrically detected magnetic resonance using radio-frequency\n  reflectometry: The authors demonstrate readout of electrically detected magnetic resonance\nat radio frequencies by means of an LCR tank circuit. Applied to a silicon\nfield-effect transistor at milli-kelvin temperatures, this method shows a\n25-fold increased signal-to-noise ratio of the conduction band electron spin\nresonance and a higher operational bandwidth of > 300 kHz compared to the kHz\nbandwidth of conventional readout techniques. This increase in temporal\nresolution provides a method for future direct observations of spin dynamics in\nthe electrical device characteristics."
    },
    {
        "anchor": "Accurate Frozen Core Approximation for All-Electron Density-Functional\n  Theory: We implement and benchmark the frozen core approximation, a technique\ncommonly adopted in electronic structure theory to reduce the computational\ncost by means of mathematically fixing the chemically inactive core electron\nstates. The accuracy and efficiency of this approach are well controlled by a\nsingle parameter, the number of frozen orbitals. Explicit corrections for the\nfrozen core orbitals and the unfrozen valence orbitals are introduced,\nsafeguarding against seemingly minor numerical deviations from the assumed\northonormality conditions of the basis functions. A speedup of over two-fold\ncan be achieved for the diagonalization step in all-electron density-functional\ntheory simulations containing heavy elements, without any accuracy degradation\nin terms of the electron density, total energy, and atomic forces. This is\ndemonstrated in a benchmark study covering 103 materials across the periodic\ntable, and a large-scale simulation of CsPbBr3 with 2,560 atoms. Our study\nprovides a rigorous benchmark of the precision of the frozen core approximation\n(sub-meV per atom for frozen core orbitals below -200 eV) for a wide range of\ntest cases and for chemical elements ranging from Li to Po. The algorithms\ndiscussed here are implemented in the open-source Electronic Structure\nInfrastructure software package.",
        "positive": "Piezoelectric Electrostatic Superlattices in Monolayer MoS$_2$: Modulation of electronic properties of materials by electric fields is\ncentral to the operation of modern semiconductor devices, providing access to\ncomplex electronic behaviors and greater freedom in tuning the energy bands of\nmaterials. Here, we explore one-dimensional superlattices induced by a\nconfining electrostatic potential in monolayer MoS$_2$, a prototypical\ntwo-dimensional semiconductor. Using first-principles calculations, we show\nthat periodic potentials applied to monolayer MoS$_2$ induce electrostatic\nsuperlattices in which the response is dominated by structural distortions\nrelative to purely electronic effects. These structural distortions reduce the\nintrinsic band gap of the monolayer substantially while also polarizing the\nmonolayer through piezoelectric coupling, resulting in spatial separation of\ncharge carriers as well as Stark shifts that produce dispersive minibands.\nImportantly, these minibands inherit the valley-selective magnetic properties\nof monolayer MoS$_2$, enabling fine control over spin-valley coupling in\nMoS$_2$ and similar transition-metal dichalcogenides."
    },
    {
        "anchor": "Single-Phase Duodenary High-Entropy Fluorite/Pyrochlore Oxides with an\n  Order-Disorder Transition: Improved thermomechanical properties have been reported for various\nhigh-entropy oxides containing typically five metal cations. This study further\ninvestigates a series of duodenary (11 metals + oxygen) high-entropy oxides by\nmixing different fractions of a five-cation fluorite-structured niobate and a\nseven-cation pyrochlore (both containing Yb) with matching lattice constants.\nNine compositions of duodenary high-entropy oxides have been examined. All of\nthem exhibit single high-entropy phases of either disordered fluorite or\nordered pyrochlore structure. An order-disorder transition (ODT) is evident\nwith changing composition, accompanied by a reduction in thermal conductivity\n(k). In comparison with the ODT criteria developed from ternary oxides, these\nduodenary oxides are more prone to disorder, but the ODT is still controlled by\nsimilar factors (but at different thresholds). Interestingly, there are abrupt\nincreases in Young's modulus (E) at low mixing concentrations near both\nendmembers. The E/k ratios are increased, in comparison with both endmembers.\nThis study suggests a new route to tailor high-entropy ceramics via controlling\ncation ordering vs. disordering.",
        "positive": "Impact of etches on thin-film single-crystal niobium resonators: A single crystal niobium thin film was grown using molecular beam epitaxy on\na c-plane sapphire wafer. Several samples were fabricated into dc resistivity\ntest devices and coplanar waveguide resonator chips using the same\nmicrofabrication procedures and solvent cleans. The samples were then subject\nto different acid cleaning treatments using different combinations of piranha,\nhydrofluoric acid, and buffered oxide etch solutions. The different samples\nexpressed changes in dc resistivity in the normal and superconducting states\nsuch that the low temperature resistivities changed by more than 100\\%, and the\nresidual resistivity ratio dropped by a factor of 2. The internal quality\nfactor of coplanar waveguide resonators measured near 5~GHz also showed\nsignificant variation at single photon powers ranging from 1.4$\\times 10^6$ to\nless than 60$\\times 10^3$. These changes correlate with the formation of\nsurface crystallites that appear to be hydrocarbons. All observations are\nconsistent with hydrogen diffusing into the niobium film at levels below the\nsaturation threshold that is needed to observe niobium hydrides."
    },
    {
        "anchor": "Slow relaxation of cascade-induced defects in Fe: On-the-fly kinetic Monte Carlo (KMC) simulations are performed to investigate\nslow relaxation of non-equilibrium systems. Point defects induced by 25 keV\ncascades in $\\alpha$-Fe are shown to lead to a characteristic time-evolution,\ndescribed by the \\emph{replenish and relax} mechanism. Then, we produce an\natomistically-based assessment of models proposed to explain the slow\nstructural relaxation by focusing on the aggregation of 50 vacancies and 25\nself-interstital atoms (SIA) in 10-lattice-parameter $\\alpha$-Fe boxes, two\nprocesses that are closely related to cascade annealing and exhibit similar\ntime signature. Four atomistic effects explain the timescales involved in the\nevolution: defect concentration heterogeneities, concentration-enhanced\nmobility, cluster-size dependent bond energies and defect-induced pressure.\nThese findings suggest that the two main classes of models to explain slow\nstructural relaxation, the Eyring model and the Gibbs model, both play a role\nto limit the rate of relaxation of these simple point-defect systems.",
        "positive": "Moir\u00e9 patterns generated by stacked 2D lattices: a general algorithm\n  to identify primitive coincidence cells: Two-dimensional materials on metallic surfaces or stacked one on top of the\nother can form a variety of moir\\'e superstructures depending on the possible\nparameter and symmetry mismatch and misorientation angle. In most cases, such\nas incommensurate lattices or identical lattices but with a small twist angle,\nthe common periodicity may be very large, thus making numerical simulations\nprohibitive. We propose here a general procedure to determine the minimal\nsimulation cell which approximates, within a certain tolerance and a certain\nsize, the primitive cell of the common superlattice, given the two interfacing\nlattices and the relative orientation angle. As case studies to validate our\nprocedure, we report two applications of particular interest: the case of\nmisaligned hexagonal/hexagonal identical lattices, describing a twisted\ngraphene bilayer or a graphene monolayer grown on Ni(111), and the case of\nhexagonal/square lattices, describing for instance a graphene monolayer grown\non Ni(100) surface. The first one, which has also analytic solutions,\nconstitutes a solid benchmark for the algorithm; the second one shows that a\nvery nice description of the experimental observations can be obtained also\nusing the resulting relatively small coincidence cells."
    },
    {
        "anchor": "Non-equilibrium VLS-grown stable ST12-Ge thin film on Si substrate: A\n  study on strain-induced band-engineering: The current work describes a novel method of growing thin films of stable\ncrystalline ST12-Ge, a high pressure polymorph of Ge, on Si substrate by a\nnon-equilibrium VLS-technique. The study explores the scheme of band\nengineering of ST12-Ge by inducing process-stress into it as a function of the\ngrowth temperature and film thickness. In the present work, ST12-Ge films are\ngrown at 180 C - 250 C to obtain thicknesses of ~4.5-7.5 nm, which possess\nextremely good thermal stability up to a temperature of ~350 C. Micro-Raman\nstudy shows the stress induced in such ST12-Ge films to be compressive in\nnature and vary in the range of ~0.5-7.5 GPa. The measured direct band gap is\nobserved to vary within 0.688 eV to 0.711 eV for such stresses, and four\nindirect band gaps are obtained to be 0.583 eV, 0.614-0.628 eV, 0.622-0.63 eV\nand 0.623-0.632 eV, accordingly. The corresponding band structures for\nunstrained and strained ST12-Ge are calculated by performing DFT simulation,\nwhich shows that a compressive stress transforms the fundamental band gap at\nM-G valley from indirect to direct one. Henceforth, the possible route of\nstrain induced band engineering in ST12-Ge is explored by analyzing all the\ntransitions in strained and unstrained band structures along with\nsubstantiation of the experimental results and theoretical calculations. The\ninvestigation shows that unstrained ST12-Ge is a natural n-type semiconductor\nwhich transforms into p-type upon incorporation of a compressive stress of ~5\nGPa, with the in-plane electron effective mass components at M-G band edge to\nbe ~0.09 me. Therefore, such band engineered ST12-Ge exhibits superior mobility\nalong with its thermal stability and compatibility with Si, which can have\npotential applications to develop high-speed MOS devices for advanced CMOS\ntechnology.",
        "positive": "Ultra-high strain in epitaxial silicon carbide nanostructures utilizing\n  residual stress amplification: Strain engineering has attracted great attention, particularly for epitaxial\nfilms grown on a different substrate. Residual strains of SiC have been widely\nemployed to form ultra-high frequency and high Q factor resonators. However, to\ndate the highest residual strain of SiC was reported to be limited to\napproximately 0.6%. Large strains induced into SiC could lead to several\ninteresting physical phenomena, as well as significant improvement of resonant\nfrequencies. We report an unprecedented nano strain-amplifier structure with an\nultra-high residual strain up to 8% utilizing the natural residual stress\nbetween epitaxial 3C SiC and Si. In addition, the applied strain can be tuned\nby changing the dimensions of the amplifier structure. The possibility of\nintroducing such a controllable and ultra-high strain will open the door to\ninvestigating the physics of SiC in large strain regimes, and the development\nof ultra sensitive mechanical sensors."
    },
    {
        "anchor": "NiTi shape-memory transformations: minimum-energy pathways between\n  austenite, martensites, and kinetically-limited intermediate states: NiTi is the most used shape-memory alloy, nonetheless, a lack of\nunderstanding remains regarding the associated structures and transitions,\nincluding their barriers. Using a generalized solid-state nudge elastic band\n(GSSNEB) method implemented via density-functional theory, we detail the\nstructural transformations in NiTi relevant to shape memory: those between\nbody-centered orthorhombic (BCO) groundstate and a newly identified stable\naustenite (\"glassy\" B2-like) structure, including energy barriers (hysteresis)\nand intermediate structures (observed as a kinetically limited R-phase), and\nbetween martensite variants (BCO orientations). All results are in good\nagreement with available experiment. We contrast the austenite results to those\nfrom the often-assumed, but unstable B2. These high- and low-temperature\nstructures and structural transformations provide much needed atomic-scale\ndetail for transitions responsible for NiTi shape-memory effects.",
        "positive": "Highly Distorted Lattices in Chemically Complex Alloys Produce\n  Ultra-Elastic Materials with Extraordinary Elinvar Effects: Conventional crystalline alloys usually possess a low atomic size difference\nin order to stabilize its crystalline structure. However, in this article, we\nreport a single phase chemically complex alloy which possesses a large atomic\nsize misfit usually unaffordable to conventional alloys. Consequently, this\nalloy develops a rather complex atomic-scale chemical order and a highly\ndistorted crystalline structure. As a result, this crystalline alloy displays\nan unusually high elastic strain limit (~2%), about ten times of that of\nconventional alloys, and an extremely low internal friction (< 2E-4) at room\ntemperature. More interestingly, this alloy firmly maintains its elastic\nmodulus even when the testing temperature rises from room temperature to 900 K,\nwhich is unmatched by the existing alloys hitherto reported. From an\napplication viewpoint, our discovery may open up new opportunities to design\nhigh precision devices usable even under an extreme environment."
    },
    {
        "anchor": "Non-volatile electric control of spin-orbit torques in an oxide\n  two-dimensional electron gas: Spin-orbit torques (SOTs) have opened a novel way to manipulate the\nmagnetization using in-plane current, with a great potential for the\ndevelopment of fast and low power information technologies. It has been\nrecently shown that two-dimensional electron gases (2DEGs) appearing at oxide\ninterfaces provide a highly efficient spin-to-charge current interconversion.\nThe ability to manipulate 2DEGs using gate voltages could offer a degree of\nfreedom lacking in the classical ferromagnetic/spin Hall effect bilayers for\nspin-orbitronics, in which the sign and amplitude of SOTs at a given current\nare fixed by the stack structure. Here, we report the non-volatile\nelectric-field control of SOTs in an oxide-based Rashba-Edelstein 2DEG. We\ndemonstrate that the 2DEG is controlled using a back-gate electric-field,\nproviding two remanent and switchable states, with a large resistance contrast\nof 1064%. The SOTs can then be controlled electrically in a non-volatile way,\nboth in amplitude and in sign. This achievement in a 2DEG-CoFeB/MgO\nheterostructures with large perpendicular magnetization further validates the\ncompatibility of oxide 2DEGs for magnetic tunnel junction integration, paving\nthe way to the advent of electrically reconfigurable SOT MRAMS circuits, SOT\noscillators, skyrmion and domain-wall-based devices, and magnonic circuits.",
        "positive": "Unfolding energy spectra of multi-periodicity materials: We propose a new unfolding scheme to analyze energy spectra of complex\nlarge-scale systems which are inherently of multi-periodicity. Considering\ntwisted bilayer graphene (tBLG) as an example, we first show that the\nconventional unfolding scheme in the past using a single primitive-cell\nrepresentation causes serious problems in analyses of the energy spectra. We\nthen introduce our multi-space representation scheme in the unfolding method\nand clarify its validity for tBLG. Velocity renormalization of Dirac electrons\nin tBLG is elucidated in the present unfolding scheme."
    },
    {
        "anchor": "Volume 78, 1 October 2014, Pages 56-64: Characterizing plasticity mechanisms below the ductile-to-brittle transition\ntemperature is traditionally difficult to accomplish in asystematic fashion.\nHere, we use a new experimental setup to perform in situ cryogenic mechanical\ntesting of pure Sn micropillars at room temperature and at 142{\\deg}C.\nSubsequent electron microscopy characterization of the micropillars shows a\nclear difference in the deformation mechanisms at room temperature and at\ncryogenic temperatures. At room temperature, the Sn micropillars deformed\nthrough dislocation plasticity, while at142{\\deg}C they exhibited both higher\nstrength and deformation twinning. Two different orientations were tested, a\nsymmetric (100) orientation and a non-symmetric (451) orientation. The\ndeformation mechanisms were found to be the same for both orientations",
        "positive": "Enhanced spin-flip scattering at the surface of copper in lateral spin\n  valves: We performed non-local electrical measurements of a series of Py/Cu lateral\nspin valve devices with different Cu thicknesses. We show that both the spin\ndiffusion length of Cu and the apparent spin polarization of Py increase with\nCu thickness. By fitting the results to a modified spin-diffusion model, we\nshow that the spin diffusion length of Cu is dominated by spin-flip scattering\nat the surface. In addition, the dependence of spin polarization of Py on Cu\nthickness is due to a strong spin-flip scattering at the Py/Cu interface."
    },
    {
        "anchor": "Quantum simulations of materials on near-term quantum computers: Quantum computers hold promise to enable efficient simulations of the\nproperties of molecules and materials; however, at present they only permit ab\ninitio calculations of a few atoms, due to a limited number of qubits. In order\nto harness the power of near-term quantum computers for simulations of larger\nsystems, it is desirable to develop hybrid quantum-classical methods where the\nquantum computation is restricted to a small portion of the system. This is of\nparticular relevance for molecules and solids where an active region requires a\nhigher level of theoretical accuracy than its environment. Here we present a\nquantum embedding theory for the calculation of strongly-correlated electronic\nstates of active regions, with the rest of the system described within density\nfunctional theory. We demonstrate the accuracy and effectiveness of the\napproach by investigating several defect quantum bits in semiconductors that\nare of great interest for quantum information technologies. We perform\ncalculations on quantum computers and show that they yield results in agreement\nwith those obtained with exact diagonalization on classical architectures,\npaving the way to simulations of realistic materials on near-term quantum\ncomputers.",
        "positive": "Donor-driven spin relaxation in multi-valley semiconductors: We present a theory for spin relaxation of electrons due to scattering off\nthe central-cell potential of impurities in silicon. Taking into account the\nmultivalley nature of the conduction band and the violation of translation\nsymmetry, the spin-flip amplitude is dominated by this short-range impurity\nscattering after which the electron is transferred to a valley on a different\naxis in $k$-space (the so called $f$-process). These $f$-processes dominate the\nspin relaxation at all temperatures, where scattering off the impurity\ncentral-cell dominate at low temperatures, and scattering with $\\Sigma$-axis\nphonons at elevated temperatures. To the best of our knowledge, the theory is\nthe first to explain and accurately quantify the empirically-found dependence\nof spin relaxation on the impurity identity. Accordingly, the new formalism\nfills a longstanding gap in the spin relaxation theory of $n$-type silicon, and\nit is valuable for characterization of silicon-based spintronic devices."
    },
    {
        "anchor": "Anharmonic corrections to the multiphonon deep-level charge capture ab\n  initio calculations for semiconductors: Nonradiative carrier recombination at semiconductor deep centers is of great\nimportance to both fundamental physics and device engineering. In this letter,\nwe provide a revised analysis of K. Huang's original nonradiative multi-phonon\n(NMP) theory with ab initio calculations. First, we identify at first-principle\nlevel that Huang's concise formula gives the same results as the matrix based\nformula, and Huang's high temperature formula provides an analytical expression\nfor the coupling constant in Marcus theory. Secondly, the anharmonic effects\nare corrected by taking into account local phonon mode variation at different\ncharge states of the defect. The corrected capture rates for defects in GaN and\nSiC agree well with experiments.",
        "positive": "Consistent Anisotropic Repulsions for Simple Molecules: We extract atom-atom potentials from the effective spherical potentials that\nsuc cessfully model Hugoniot experiments on molecular fluids, e.g., $O_2$ and\n$N_2$. In the case of $O_2$ the resulting potentials compare very well with the\natom-atom potentials used in studies of solid-state propertie s, while for\n$N_2$ they are considerably softer at short distances. Ground state (T=0K) and\nroom temperatu re calculations performed with the new $N-N$ potential resolve\nthe previous discrepancy between experimental and theoretical results."
    },
    {
        "anchor": "Micromechanical study of the dilatational response of porous solids with\n  pressure-insensitive matrix displaying tension-compression asymmetry: In this paper, the dilatational response of porous solids with\npressure-insensitive matrix displaying strength differential (SD) effects is\ninvestigated. To this end, micromechanical finite-element analyses of\nthree-dimensional unit cells are carried out. The matrix behavior is governed\nby the isotropic form of Cazacu et al. (2006) criterion that accounts for SD\neffects through a parameter k. Simulation results are presented for\naxisymmetric tensile loadings corresponding to fixed values of the stress\ntriaxiality for the two possible values of the Lode parameter, LP. For moderate\nand high stress triaxialities, it is shown that for materials for which the\nmatrix tensile strength is larger than its compressive strength (k > 0), under\ntensile loadings corresponding at LP=1 the void growth rate is much faster than\nin the case of tensile loadings at LP=-1. The opposite holds true for materials\nwith matrix tensile strength lower than its compressive strength (k< 0). This\ndrastic difference in porosity evolution is explained by the distribution of\nthe local plastic strain and stresses, which are markedly different than in a\nvon Mises material (i.e. no SD effects of the matrix).",
        "positive": "Hybrid electrochromic device with Tungsten oxide (WO3-x) and nafion\n  membrane: performance with varying tungsten oxide thickness: Electrochromic devices, which dynamically change color under the applied\npotential, are widely studied because of its wide range of applications such as\nenergy-efficient smart windows, rear view mirrors and display devices etc. In\nthis study we are reporting four layer electrochromic device based on tungsten\noxide as a electrochromic layer and nafion membrane as a ionic conducting\nlayer. Nafion membranes are generally used in fuel cell applications because of\nits high ionic conductivity and high optical transparency which is suitable for\nelectrochromic device to attain higher efficiencies. We have prepared an\nelectrochromic device by sandwiching ITO coated glass and WO3 coated ITO thin\nfilm between nafion membrane. The overall structure of the device is\nGlass/ITO/WO3/Nafion/ITO/Glass. We deposited tungsten oxide thin films with\ndifferent thickness on ITO coated glass substrate at room temperature by using\nreactive DC Magnetron sputtering and we studied the performance of the\nelectrochromic device with the function of thickness. We have observed that\nelectrochromic efficiency is increasing with increase in the tungsten oxide\nlayer thickness. The efficiency of the device increased from 24.8 cm2/C to\n184.3 cm2/C."
    },
    {
        "anchor": "The nature of ferromagnetism in the chiral helimagnet $Cr_{1/3}NbS_{2}$: The chiral helimagnet, $Cr_{1/3}NbS_{2}$, hosts exotic spin textures, whose\ninfluence on the magneto-transport properties, make this material an ideal\ncandidate for future spintronic applications. To date, the interplay between\nmacroscopic magnetic and transport degrees of freedom is believed to result\nfrom a reduction in carrier scattering following spin order. Here, we present\nelectronic structure measurements through the helimagnetic transition\ntemperature, $T_{C}$ that challenges this view by showing a Fermi surface\ncomprised of strongly hybridized Nb- and Cr- derived electronic states, and\nspectral weight in proximity to the Fermi level to anomalously increases as\ntemperature is lowered below $T_{C}$. These findings are rationalized on the\nbasis of first principle, density functional theory calculations, which reveal\na large nearest-neighbor exchange energy, suggesting the interaction between\nlocal spin moments and hybridized Nb- and Cr- derived itinerant states to go\nbeyond the perturbative interaction of Ruderman-Kittel-Kasuya-Yosida,\nsuggesting instead a mechanism rooted in a Hund's exchange interaction.",
        "positive": "Confinement-Induced Liquid Crystalline Transitions and Chirality\n  Inversion in Amyloid Fibril Cholesteric Tactoids: Chirality is ubiquitous in nature and plays crucial roles in biology,\nmedicine, physics and materials science. Understanding and controlling\nchirality is therefore an important research challenge with broad implications\nin fundamental and applied sciences. Unlike other classes of chiral colloids,\nsuch as nanocellulose or filamentous viruses, amyloid fibrils form nematic\nphases but appear to miss their twisted form in the phase diagram, the\nso-called cholesteric or chiral nematic phases, and this despite a well-defined\nchirality at the single fibril level. Here we report the discovery of\ncholesteric phases in amyloid fibrils, by using \\b{eta}-lactoglobulin fibrils\nsuitably shortened by shear stresses. The physical behavior of this new class\nof cholesteric materials exhibits unprecedented structural complexity, with\nconfinement-drivenordering transitions between at least three types of nematic\nand cholesteric tactoids. We use energy functional theory to rationalize these\nresults and demonstrate a chirality inversion upon increasing hierarchical\nlevels, from the left-handed amyloids to the right-handed cholesteric droplets.\nThese findings significantly deepen our understanding of chiral nematic phases\nand may pave the way to their optimal use in soft nanotechnology, nanomaterials\ntemplating and self-assembly."
    },
    {
        "anchor": "Experimental determination of the bare energy gap of GaAs without the\n  zero-point renormalization: The energy gap of simple band insulators like GaAs is a strong function of\ntemperature due to the electron-phonon interactions. Interestingly, the\nperturbation from zero-point phonons is also predicted to cause significant (a\nfew percent) renormalization of the energy gap at absolute zero temperature but\nits value has been difficult to estimate both theoretically and, of course,\nexperimentally. Given the experimental evidence [Bhattacharya, et al., Phys.\nRev. Lett. 114, 047402 (2015)] that strongly supports that the exponential\nbroadening (Urbach tail) of the excitonic absorption edge at low temperatures\nis the manifestation of this zero temperature electron-phonon scattering, we\nargue that the location of the Urbach focus is the zero temperature\nunrenormalized gap. Experiments on GaAs yield the zero temperature bare energy\ngap to be 1.581 eV and thus the renormalization is estimated to be 66 meV.",
        "positive": "Transport and Magnetism in p-type cubic (Ga,Mn)N: The electrical and magnetic properties of p-type cubic (Ga,Mn)N thin films\ngrown by plasma-assisted molecular beam epitaxy are reported. Hole\nconcentrations in excess of 1018 cm-3 at room temperature are observed.\nActivated behaviour is observed down to around 150K, characterised by an\nacceptor ionisation energy of around 45-60meV. The dependence of hole\nconcentration and ionisation energy on Mn concentration indicates that the\nshallow acceptor level is not simply due to unintentional co-doping.\nThermopower measurements on freestanding films, CV profilometry, and the\ndependence of conductivity on thickness and growth temperature, all show that\nthe conduction is not due to diffusion into the substrate. We therefore\nassociate the p-type conductivity with the presence of the Mn in the cubic GaN\nfilms. Magnetometry measurements indicate a small room temperature\nferromagnetic phase, and a significantly larger magnetic coupling at low\ntemperatures."
    },
    {
        "anchor": "Fully relativistic $GW$/Bethe-Salpeter calculations in BerkeleyGW:\n  implementation, symmetries, benchmarking, and performance: Computing the $GW$ quasiparticle bandstructure and Bethe-Salpeter Equation\n(BSE) absorption spectra for materials with spin-orbit coupling has commonly\nbeen done by treating $GW$ corrections and spin-orbit coupling as separate\nperturbations to density-functional theory. However, accurate treatment of\nmaterials with strong spin-orbit coupling often requires a fully relativistic\napproach using spinor wavefunctions in the Kohn-Sham equation and $GW$/BSE.\nSuch calculations have only recently become available, in particular for the\nBSE. We have implemented this approach in the plane-wave pseudopotential\n$GW$/BSE code BerkeleyGW, which is highly parallelized and widely used in the\nelectronic-structure community. We present reference results for quasiparticle\nbandstructures and optical absorption spectra of solids with different\nstrengths of spin-orbit coupling, including Si, Ge, GaAs, GaSb, CdSe, Au, and\nBi$_2$Se$_3$. The calculated quasiparticle band gaps of these systems are found\nto agree with experiment to within a few tens of meV. The absorption spectrum\nof GaSb calculated with the fully-relativistic $GW$-BSE captures the large\nspin-orbit splitting of peaks in the spectrum. For Bi$_2$Se$_3$, we find a\ndrastic change in the low-energy bandstructure compared to that of DFT, with\nthe fully-relativistic treatment of the $GW$ approximation correctly capturing\nthe parabolic nature of the valence and conduction bands after including\noff-diagonal self-energy matrix elements. We present the detailed methodology,\napproach to spatial symmetries for spinors, comparison against other codes, and\nperformance compared to spinless $GW$/BSE calculations and perturbative\napproaches to SOC. This work aims to spur further development of spinor\n$GW$/BSE methodology in excited-state research software.",
        "positive": "Structural and electrical properties of CdS thin films spin coated on\n  glass substrates: CdS samples were synthesized on amorphous glass and conductive glass\nsubstrates at room temperature using spin coating technique and subsequently\nannealed at five different temperatures in air for one hour. The speed and time\nof spin coating were varied initially to optimize the properties of the\nsamples. FTIR spectroscopy was used in this experiment to analyze CdS bond\nformation variation with annealing temperature. A liquid junction photocell\nwith KI/I2 electrolyte was prepared to measure the photovoltaic properties.\nPhotovoltage, photocurrent and corresponding output power were measured in\norder to determine the output power."
    },
    {
        "anchor": "Oxygen-Terminated (1x1) Reconstruction of Reduced Magnetite\n  Fe$_3$O$_4$(111): The (111) facet of magnetite (Fe$_3$O$_4$) has been studied extensively by\nexperimental and theoretical methods, but controversy remains regarding the\nstructure of its low-energy surface terminations. Using density functional\ntheory (DFT) computations, we demonstrate three reconstructions that are more\nfavorable than the accepted Fe$_{\\rm oct2}$ termination in reducing conditions.\nAll three structures change the coordination of iron in the kagome Fe$_{\\rm\noct1}$ layer to tetrahedral. With atomically-resolved microscopy techniques, we\nshow that the termination that coexists with the Fe$_{\\rm tet1}$ termination\nconsists of tetrahedral iron capped by three-fold coordinated oxygen atoms.\nThis structure explains the inert nature of the reduced patches.",
        "positive": "Coupling time scales for simulation of structure transformation: an\n  attempt to combine molecular dynamics and phase-field theory: A multiscale scheme combining molecular dynamics (MD) and microscopic\nphase-field theory is proposed to study the structural phase transformations in\nsolids with inhomogeneous strain field. The approach calculates strain response\nbased on MD and atomic diffusion based on the phase field theory. Simulations\nwith the new technique are conducted in two examples. The first involves\ninterface roughening in a Co/Cu thin film, where interfacial undulations due to\nlattice mismatch is demonstrated. The second example is a study of spinodal\ndecomposition in AgCo/Pt/MgO(001) thin film, where we show that Co atoms are\nattracted by dislocations in the Pt/MgO interface, producing an interesting\nnanostructure."
    },
    {
        "anchor": "Non-collinear Antiferromagnets and the Anomalous Hall Effect: The anomalous Hall effect is investigated theoretically by means of density\nfunctional calculations for the non-collinear antiferromagnetic order of the\nhexagonal compounds Mn$_3$Ge and Mn$_3$Sn using various planar triangular\nmagnetic configurations as well as unexpected non-planar configurations. The\nformer give rise to anomalous Hall conductivities (AHC) that are found to be\nextremely anisotropic. For the planar cases the AHC is connected with\nWeyl-points in the energy-band structure, which are described in detail. If\nthis case were observable in Mn$_3$Ge, a large AHC of about 900 S/cm should be\nexpected. However, in Mn$_3$Ge it is the non-planar configuration that is\nenergetically favored, in which case it gives rise to an AHC of 100 S/cm. The\nnon-planar configuration allows a quantitative evaluation of the topological\nHall effect that is seen to determine this value of the conductivity to a large\nextent. For Mn$_3$Sn it is the planar configurations that are predicted to be\nobservable. In this case the AHC can be as large as 250 S/cm.",
        "positive": "Revealing and exploiting hierarchical material structure through complex\n  atomic networks: One of the great challenges of modern science is to faithfully model, and\nunderstand, matter at a wide range of scales. Starting with atoms, the vastness\nof the space of possible configurations poses a formidable challenge to any\nsimulation of complex atomic and molecular systems. We introduce a\ncomputational method to reduce the complexity of atomic configuration space by\nsystematically recognising hierarchical levels of atomic structure, and\nidentifying the individual components. Given a list of atomic coordinates, a\nnetwork is generated based on the distances between the atoms. Using the\ntechnique of modularity optimisation, the network is decomposed into modules.\nThis procedure can be performed at different resolution levels, leading to a\ndecomposition of the system at different scales, from which hierarchical\nstructure can be identified. By considering the amount of information required\nto represent a given modular decomposition we can furthermore find the most\nsuccinct descriptions of a given atomic ensemble. Our straightforward,\nautomatic and general approach is applied to complex crystal structures. We\nshow that modular decomposition of these structures considerably simplifies\nconfiguration space, which in turn can be used in discovery of novel crystal\nstructures, and opens up a pathway towards accelerated molecular dynamics of\ncomplex atomic ensembles. The power of this approach is demonstrated by the\nidentification of a possible allotrope of boron containing 56 atoms in the\nprimitive unit cell, which we uncover using an accelerated structure search,\nbased on a modular decomposition of a known dense phase of boron,\n$\\gamma$-B$_{28}$."
    },
    {
        "anchor": "Ferroelastic twin angles at the surface of CaTiO$_\\mathrm{3}$ quantified\n  by PhotoEmission Electron Microscopy: We use photoemission electron microscopy to measure the ferroelastic twin\nwall angles at the surface of CaTiO$_\\mathrm{3}$(001) and deduce the strain\nordering. We analyze the angular dependence of the photoelectron emission from\ndifferent domain surfaces, each with their own characteristic tilt angle in the\nfactory roof-like topography. By considering the surface topography as a field\nperturbation, the offset in the photoemission threshold can be directly related\nto the tilt angles. With knowledge of the symmetry allowed twin walls we\nquantify twin topography between 179.1{\\deg} to 180.8{\\deg}.",
        "positive": "Dielectric response of laser-excited silicon: We calculate the dielectric response of crystalline silicon following\nirradiation by a high-intensity laser pulse, modeling the dynamics by\ntime-dependent density functional theory (TDDFT). The pump-probe measurements\nare numerically simulated by solving the time-dependent Kohn-Sham equation with\nthe pump and probe fields included as external fields. As expected, the excited\nsilicon shows features of a particle-hole plasma in its response. We compare\nthe calculated response with a thermal model and with a simple Drude model. The\nthermal model requires only a static DFT calculation to prepare electronically\nexcited matter and agrees rather well with the TDDFT for the same particle-hole\ndensity. The Drude model with two fitted parameters (electron effective mass\nand collision time) also shows fair agreement at the lower excitation energies;\nthe fitted effective masses are consistent with carrier-band dispersions. The\nextracted Drude lifetimes range from 6 fs at weak pumping fields to much lower\nvalues at high fields. However, we find that the Drude model does not give a\ngood fit to the imaginary dielectric function at the highest fields. Comparing\nthe thermal model with the Drude, we find that the extracted lifetimes are in\nthe same range, 1-13 fs depending on the temperature. These short Drude\nlifetimes show that strong damping is possible in the TDDFT, despite the\nabsence of electron scattering. One significant difference between the TDDFT\nresponse and the other models is that the response to the probe pulse depends\non the polarization of the pump pulse. We also find that the imaginary part of\nthe dielectric function can be negative, particularly for the parallel\npolarization of pump and probe fields."
    },
    {
        "anchor": "STM microscopy of the CDW in 1T-TiSe2 in the presence of single atom\n  defects: We present a detailed low temperature scanning tunneling microscopy study of\nthe commensurate charge density wave (CDW) in 1$T$-TiSe$_2$ in the presence of\nsingle atom defects. We find no significant modification of the CDW lattice in\nsingle crystals with native defects concentrations where some bulk probes\nalready measure substantial reductions in the CDW phase transition signature.\nSystematic analysis of STM micrographs combined with density functional theory\nmodelling of atomic defect patterns indicate that the observed CDW modulation\nlies in the Se surface layer. The defect patterns clearly show there are no\n2$H$-polytype inclusions in the CDW phase, as previously found at room\ntemperature [Titov A.N. et al, Phys. Sol. State 53, 1073 (2011). They further\nprovide an alternative explanation for the chiral Friedel oscillations recently\nreported in this compound [J. Ishioka et al., Phys. Rev. B 84, 245125, (2011)].",
        "positive": "Magnetic anisotropy of Fe_1-yX_yPt-L10 [X=Cr,Mn,Co,Ni,Cu] bulk alloys: We demonstrate by means of fully relativistic first principles calculations\nthat, by substitution of Fe by Cr, Mn, Co, Ni or Cu in FePt-L10 bulk alloys,\nwith fixed Pt content, it is possible to tune the magnetocrystalline anisotropy\nenergy by adjusting the content of the non-magnetic species in the material.\nThe changes in the geometry due to the inclusion of each element induces\ndifferent values of the tetragonality and hence changes in the magnetic\nanisotropy and in the net magnetic moment. The site resolved magnetic moments\nof Fe increase with the X content whilst those of Pt and X are simultaneously\nreduced. The calculations are in good quantitative agreement with experimental\ndata and demonstrate that models with fixed band structure but varying numbers\nof electrons per unit cell are insufficient to describe the experimental data\nfor doped FePt-L10 alloys."
    },
    {
        "anchor": "First-principles study of two-dimensional electron and hole gases at the\n  head-to-head and tail-to-tail 180$^\\circ$ domain walls in PbTiO$_{3}$\n  ferroelectric thin films: We study from first-principles the structural and electronic properties of\nhead-to-head (HH) and tail-to-tail (TT) 180$^\\circ$ domain walls in isolated\nfree-standing PbTiO$_{3}$ slabs. For sufficiently thick domains ($n$ = 16 unit\ncells of PbTiO$_{3}$), a transfer of charge from the free surfaces to the\ndomain walls to form localized electron (in the HH) and hole (in the TT) gases\nin order to screen the bound polarization charges is observed. The\nelectrostatic driving force behind this electronic reconstruction is clearly\nvisible from the perfect match between the smoothed free charge densities and\nthe bound charge distribution, computed from a finite difference of the\npolarization profile obtained after the relaxation of the lattice degrees of\nfreedom. The domain wall widths, of around six unit cells, are larger than in\nthe conventional 180$^\\circ$ neutral configurations. Since no oxygen vacancies,\ndefects or dopant atoms are introduced in our simulations, all the previous\nphysical quantities are the intrinsic limits of the system. Our results support\nthe existence of an extra source of charge at the domains walls to explain the\nenhancement of the conductivity observed in some domains walls of prototypical,\ninsulating in bulk, perovskite oxides.",
        "positive": "Metal to insulator transition, colossal Seebeck coefficient and ultralow\n  thermal conductivity in solution-processed monodispersed nickel nanoparticles: We report here metal to insulator transition, colossal Seebeck coefficient\nand ultralow thermal conductivity (0.0057th of its bulk value, significantly\nsmaller than many well-known thermoelectric materials and silicon, showing\npotential applications in thermoelectrics, electronics and photonics for heat\ndissipation) in monodispersed well characterized Ni nanoparticles. As a\nconsequence, thermoelectric power factor and figure of merit are significantly\nenhanced compared to their bulk counterpart. Interestingly, a systematic\ncrossover from metallic to semiconducting to finally electrically insulating\nbehavior, large negative temperature coefficient of resistance and n-type\nconduction to p-type conduction with decrease in particle size have been\nobserved. These results are mainly attributed to formation of metal/organic\ninterfaces, enhancement in local electronic density of sates and multiscale\nelectron and phonon scattering by various defects. Thus, this study will open a\nnew avenue to make better thermoelectrics through incorporation of such\nnanoparticles in semiconducting hosts."
    },
    {
        "anchor": "Ultrasensitive Field-Effect Biosensors Enabled by the Unique Electronic\n  Properties of Graphene: This review provides a critical overview of current developments on\nnanoelectronic biochemical sensors based on graphene. Composed of a single\nlayer of conjugated carbon atoms, graphene has outstanding high carrier\nmobility and low intrinsic electrical noise, but a chemically inert surface.\nSurface functionalization is therefore crucial to unravel graphene sensitivity\nand selectivity for the detection of targeted analytes. To achieve optimal\nperformance of graphene transistors for biochemical sensing, the tuning of the\ngraphene surface properties via surface functionalization and passivation is\nhighlighted, as well as the tuning of its electrical operation by utilizing\nmultifrequency ambipolar configuration and a high frequency measurement scheme\nto overcome the Debye screening to achieve low noise and highly sensitive\ndetection. Potential applications and prospectives of ultrasensitive graphene\nelectronic biochemical sensors ranging from environmental monitoring and food\nsafety, healthcare and medical diagnosis, to life science research, are\npresented as well.",
        "positive": "Local structure of relaxor ferroelectric Sr$_x$Ba$_{1-x}$Nb$_2$O$_6$\n  from pair distribution function analysis: Neutron pair distribution function analysis and first principles calculations\nhave been employed to study short-range correlations in heavily disordered\ndielectric material Sr$_x$Ba$_{1-x}$Nb$_2$O$_6$ ($x=0.35, 0.5$ and 0.61). The\ncombination of methods has been fruitful in pinpointing main local-structure\nfeatures, their temperature behaviour and interrelation. A rather complex\nsystem of tilts is found to be both temperature and Sr-content sensitive with\nthe biggest tilt magnitudes reached at low temperatures and high $x$. Relative\nNb-O$_6$ displacements, directly responsible for material's ferroelectric\nproperties, are shown to be distinct in two octahedra sub-systems with\ndifferent freezing temperatures and disparate levels of deviation from\nmacroscopic polarization direction. Intrinsic disorder caused by Sr, Ba and\nvacancy distribution is found to introduce local strain to the structure and\ndirectly influence octahedra tilting. These findings establish a new atomistic\npicture of the local structure -- property relationship in\nSr$_x$Ba$_{1-x}$Nb$_2$O$_6$."
    },
    {
        "anchor": "In situ quantitative study of plastic strain-induced phase\n  transformations under high pressure: Example for ultra-pure Zr: The first in situ quantitative synchrotron X-ray diffraction (XRD) study of\nplastic strain-induced phase transformation (PT) has been performed on\n$\\alpha-\\omega$ PT in ultra-pure, strongly plastically predeformed Zr as an\nexample, under different compression-shear pathways in rotational diamond anvil\ncell (RDAC). Radial distributions of pressure in each phase and in the mixture,\nand concentration of $\\omega$-Zr, all averaged over the sample thickness, as\nwell as thickness profile were measured. The minimum pressure for the\nstrain-induced $\\alpha-\\omega$ PT, $p^d_{\\varepsilon}$=1.2 GPa, is smaller than\nunder hydrostatic loading by a factor of 4.5 and smaller than the phase\nequilibrium pressure by a factor of 3; it is independent of the\ncompression-shear straining path. The theoretically predicted plastic\nstrain-controlled kinetic equation was verified and quantified; it is\nindependent of the pressure-plastic strain loading path and plastic deformation\nat pressures below $p^d_{\\varepsilon}$. Thus, strain-induced PTs under\ncompression in DAC and torsion in RDAC do not fundamentally differ. The yield\nstrength of both phases is estimated using hardness and x-ray peak broadening;\nthe yield strength in shear is not reached by the contact friction stress and\ncannot be evaluated using the pressure gradient. Obtained results open a new\nopportunity for quantitative study of strain-induced PTs and reactions with\napplications to material synthesis and processing, mechanochemistry, and\ngeophysics.",
        "positive": "PARC: Physics-Aware Recurrent Convolutional Neural Networks to\n  Assimilate Meso-scale Reactive Mechanics of Energetic Materials: The thermo-mechanical response of shock-initiated energetic materials (EM) is\nhighly influenced by their microstructures, presenting an opportunity to\nengineer EM microstructure in a \"materials-by-design\" framework. However, the\ncurrent design practice is limited, as a large ensemble of simulations is\nrequired to construct the complex EM structure-property-performance linkages.\nWe present the Physics-Aware Recurrent Convolutional (PARC) Neural Network, a\ndeep-learning algorithm capable of learning the mesoscale thermo-mechanics of\nEM from a modest number of high-resolution direct numerical simulations (DNS).\nValidation results demonstrated that PARC could predict the themo-mechanical\nresponse of shocked EM with a comparable accuracy to DNS but with notably less\ncomputation time. The physics awareness of PARC enhances its modeling\ncapabilities and generalizability, especially when challenged in unseen\nprediction scenarios. We also demonstrate that visualizing the artificial\nneurons at PARC can shed light on important aspects of EM thermos-mechanics and\nprovide an additional lens for conceptualizing EM."
    },
    {
        "anchor": "Quantum computing with defects: Identifying and designing physical systems for use as qubits, the basic units\nof quantum information, are critical steps in the development of a quantum\ncomputer. Among the possibilities in the solid state, a defect in diamond known\nas the nitrogen-vacancy (NV-1) center stands out for its robustness - its\nquantum state can be initialized, manipulated, and measured with high fidelity\nat room temperature. Here we describe how to systematically identify other deep\ncenter defects with similar quantum-mechanical properties. We present a list of\nphysical criteria that these centers and their hosts should meet and explain\nhow these requirements can be used in conjunction with electronic structure\ntheory to intelligently sort through candidate defect systems. To illustrate\nthese points in detail, we compare electronic structure calculations of the\nNV-1 center in diamond with those of several deep centers in 4H silicon carbide\n(SiC). We then discuss the proposed criteria for similar defects in other\ntetrahedrally-coordinated semiconductors.",
        "positive": "Room-temperature delayed giant magnetodielectric effects observed in\n  Bi4Fe2TiO12 film: This letter reports our experimental results on magnetic-field-induced\naftereffects in solution derived Bi4Fe2TiO12 film, in which e' decreases as\nmuch as 600 times after treated in a 5T magnetic field as that of the pristine\none. The phenomena are explained by an unusual spin-orbital coupling in film,\nwhere strong magnetic field provides drive force for spin polarized electrons\nof electrode to enter film, so as to form a ferromagnetic orbital state,\nincrease the relaxation time of defect dipoles and then produce giant\nmagnetodielectric effects. This process is reversible just by applying a\nopposite 0.5T magnetic field. Our findings have potential applications on\nmagnetic fabrication of nanopatterns somehow to evade nanohazard, as well as on\nintegraged phononic or photonic crystals on chip."
    },
    {
        "anchor": "Superlens made of a metamaterial with extreme effective parameters: We propose a superlens formed by an ultra-dense array of crossed metallic\nwires. It is demonstrated that due to the anomalous interaction between crossed\nwires, the structured substrate is characterized by an anomalously high index\nof refraction and supports strongly confined guided modes with very short\npropagation wavelengths. It is theoretically proven that a planar slab of such\nstructured material makes a superlens that may compensate for the attenuation\nintroduced by free-space propagation and restore the subwavelength details of\nthe source. The bandwidth of the proposed device can be quite significant since\nthe response of the structured substrate is non-resonant. The theoretical\nresults are fully supported by numerical simulations.",
        "positive": "Neural network approach for a rapid prediction of metal-supported\n  borophene properties: We develop a high-dimensional neural network potential (NNP) to describe the\nstructural and energetic properties of borophene deposited on silver. This NNP\nhas the accuracy of DFT calculations while achieving computational speedups of\nseveral orders of magnitude, allowing the study of extensive structures that\nmay reveal intriguing moir\\'e patterns or surface corrugations. We describe an\nefficient approach to constructing the training data set using an iterative\ntechnique known as the \"adaptive learning approach\". The developed NNP\npotential is able to produce, with an excellent agreement, the structure,\nenergy and forces of DFT. Finally, the calculated stability of various\nborophene polymorphs, including those not initially included in the training\ndataset, shows better stabilization for $\\nu\\sim0.1$ hole density, and in\nparticular for the allotrope $\\alpha$ ($\\nu=\\frac{1}{9}$). The stability of\nborophene on the metal surface is shown to depend on its orientation, implying\nstructural corrugation patterns that can only be observed from long time\nsimulations on extended systems. The NNP also demonstrates its ability to\nsimulate vibrational densities of states and produce realistic structures, with\nsimulated STM images closely matching the experimental ones."
    },
    {
        "anchor": "Materials property prediction using symmetry-labeled graphs as\n  atomic-position independent descriptors: Computational materials screening studies require fast calculation of the\nproperties of thousands of materials. The calculations are often performed with\nDensity Functional Theory (DFT), but the necessary computer time sets\nlimitations for the investigated material space. Therefore, the development of\nmachine learning models for prediction of DFT calculated properties are\ncurrently of interest. A particular challenge for \\emph{new} materials is that\nthe atomic positions are generally not known. We present a machine learning\nmodel for the prediction of DFT-calculated formation energies based on Voronoi\nquotient graphs and local symmetry classification without the need for detailed\ninformation about atomic positions. The model is implemented as a message\npassing neural network and tested on the Open Quantum Materials Database (OQMD)\nand the Materials Project database. The test mean absolute error is 20 meV on\nthe OQMD database and 40 meV on Materials Project Database. The possibilities\nfor prediction in a realistic computational screening setting is investigated\non a dataset of 5976 ABSe$_3$ selenides with very limited overlap with the OQMD\ntraining set. Pretraining on OQMD and subsequent training on 100 selenides\nresult in a mean absolute error below 0.1 eV for the formation energy of the\nselenides.",
        "positive": "Excitons in boron nitride nanotubes: dimensionality effects: We show that the optical absorption spectra of boron nitride (BN) nanotubes\nare dominated by strongly bound excitons. Our first-principles calculations\nindicate that the binding energy for the first and dominant excitonic peak\ndepends sensitively on the dimensionality of the system, varying from 0.7 eV in\nbulk hexagonal BN via 2.1 eV in the single sheet of BN to more than 3 eV in the\nhypothetical (2,2) tube. The strongly localized nature of this exciton dictates\nthe fast convergence of its binding energy with increasing tube diameter\ntowards the sheet value. The absolute position of the first excitonic peak is\nalmost independent of the tube radius and system dimensionality. This provides\nan explanation for the observed \"optical gap\" constancy for different tubes and\nbulk hBN [R. Arenal et al., to appear in Phys. Rev. Lett. (2005)]."
    },
    {
        "anchor": "Unified topological characterization of electronic states in spin\n  textures from noncommutative K-theory: The nontrivial topology of spin systems such as skyrmions in real space can\npromote complex electronic states. Here, we provide a general viewpoint at the\nemergence of topological electronic states in spin systems based on the methods\nof noncommutative K-theory. By realizing that the structure of the observable\nalgebra of spin textures is determined by the algebraic properties of the\nnoncommutative hypertorus, we arrive at a unified understanding of topological\nelectronic states which we predict to arise in various noncollinear setups. The\npower of our approach lies in an ability to categorize emergent topological\nstates algebraically without referring to smooth real- or reciprocal-space\nquantities. This opens a way towards an educated design of topological phases\nin aperiodic, disordered, or non-smooth textures of spins and charges\ncontaining topological defects.",
        "positive": "Exciton-Phonon Interaction and Relaxation Times from First Principles: Electron-phonon ($e$-ph) interactions are key to understanding the dynamics\nof electrons in materials, and can be modeled accurately from first-principles.\nHowever, when electrons and holes form Coulomb-bound states (excitons),\nquantifying their interactions and scattering processes with phonons remains an\nopen challenge. Here we show a rigorous approach for computing exciton-phonon\n(ex-ph) interactions and the associated exciton dynamical processes from first\nprinciples. Starting from the ab initio Bethe-Salpeter equation, we derive\nexpressions for the ex-ph matrix elements and relaxation times. We apply our\nmethod to bulk hexagonal boron nitride, for which we map the ex-ph relaxation\ntimes as a function of exciton momentum and energy, analyze the temperature and\nphonon-mode dependence of the ex-ph scattering processes, and accurately\npredict the phonon-assisted photoluminescence. The approach introduced in this\nwork is general and provides a framework for investigating exciton dynamics in\na wide range of materials."
    },
    {
        "anchor": "Robustness of \"cut and splice\" genetic algorithms in the structural\n  optimization of atomic clusters: We return to the geometry optimization problem of Lennard-Jones clusters to\nanalyze the performance dependence of \"cut and splice\" genetic algorithms (GAs)\non the employed population size. We generally find that admixing twinning\nmutation moves leads to an improved robustness of the algorithm efficiency with\nrespect to this a priori unknown technical parameter. The resulting very stable\nperformance of the corresponding mutation+mating GA implementation over a wide\nrange of population sizes is an important feature when addressing unknown\nsystems with computationally involved first-principles based GA sampling.",
        "positive": "Calculations of excess free energies of precipitates via direct\n  thermodynamic integration across phase boundaries: We describe a technique for constraining macroscopic fluctuations in\nthermodynamic variables well-suited for Monte Carlo (MC) simulations of\nmultiphase equilibria. In particular for multicomponent systems this amounts to\na statistical ensemble that implements constraints on both the average\ncomposition as well as its fluctuations. The variance-constrained\nsemi-grandcanonical (VC-SGC) ensemble allows for MC simulations, in which\nsingle-phase systems can be reversibly switched into multiphase equilibria\nallowing the calculation of excess free energies of precipitates of complex\nshapes by thermodynamic integration. The basic features as well as the scaling\nand convergence properties of this technique are demonstrated by application to\nan Ising model. Finally, the VC-SGC MC simulation technique is used to\ncalculate alpha/alpha' interface free energies in Fe-Cr alloys as a function of\norientation and temperature taking into account configurational, vibrational,\nand structural degrees of freedom."
    },
    {
        "anchor": "Quantum Effects in the Acoustic Plasmons of Atomically-Thin\n  Heterostructures: Recent advances in nanofabrication technology now enable unprecedented\ncontrol over 2D heterostructures, in which single- or few-atom thick materials\nwith synergetic opto-electronic properties can be combined to develop\nnext-generation nanophotonic devices. Precise control of light can be achieved\nat the interface between 2D metal and dielectric layers, where surface plasmon\npolaritons strongly confine electromagnetic energy. Here we reveal quantum and\nfinite-size effects in hybrid systems consisting of graphene and\nfew-atomic-layer noble metals, based on a quantum description that captures the\nelectronic band structure of these materials. These phenomena are found to play\nan important role in the metal screening of the plasmonic fields, determining\nthe extent to which they propagate in the graphene layer. In particular, we\nfind that a monoatomic metal layer is capable of pushing graphene plasmons\ntoward the intraband transition region, rendering them acoustic, while the\naddition of more metal layers only produces minor changes in the dispersion but\nstrongly affects the lifetime. We further find that a quantum approach is\nrequired to correctly account for the sizable Landau damping associated with\nsingle-particle excitations in the metal. We anticipate that these results will\naid in the design of future platforms for extreme light-matter interaction on\nthe nanoscale.",
        "positive": "GW band structure of monolayer MoS2 using the SternheimerGW method and\n  effect of dielectric environment: Monolayers of transition-metal dichalcogenides (TMDs) hold great promise as\nfuture nanoelectronic and optoelectronic devices. An essential feature for\nachieving high device performance is the use of suitable supporting substrates,\nwhich can affect the electronic and optical properties of these two-dimensional\n(2D) materials. Here, we perform many-body GW calculations using the\nSternheimerGW method to investigate the quasiparticle band structure of\nmonolayer MoS2 subject to an effective dielectric screening model, which is\nmeant to approximately describe substrate polarization in real device\napplications. We show that, within this model, the dielectric screening has a\nsizable effect on the quasiparticle band gap; for example, the gap\nrenormalization is as large as 250 meV for MoS2 with model screening\ncorresponding to SiO2. Within the G0W0 approximation, we also find that the\ninclusion of the effective screening induces a direct band gap, in contrast to\nthe unscreened monolayer. We also find that the dielectric screening induces an\nenhancement of the carrier effective masses by as much as 27% for holes, shifts\nplasmon satellites, and redistributes quasiparticle weight. Our results\nhighlight the importance of the dielectric environment in the design of 2D\nTMD-based devices."
    },
    {
        "anchor": "Direct evidence for intermediate multiferroic phase in LiCuFe2(VO4)3: Magnetic susceptibility, specific heat, dielectric, and electric polarization\nof LiCuFe2(VO4)3 have been investigated. Two sequential antiferromagnetic\ntransitions at TN1 ~ 9.95 K and TN2 ~ 8.17 K are observed under zero magnetic\nfield. While a dielectric peak at TN1 is clearly identified, the measured\npyroelectric current also exhibits a sharp peak at TN1, implying the\nmagnetically relevant ferroelectricity. Interestingly, another pyroelectric\npeak around TN2 with opposite signal is observed, resulting in the\ndisappearance of electric polarization below TN2. Besides, the electric\npolarization is significantly suppressed in response to external magnetic\nfield, evidencing remarkable magnetoelectric effect. These results suggest the\nessential relevance of the magnetic structure with the ferroelectricity in\nLiCuFe2(VO4)3, deserving for further investigation of the underlying mechanism.",
        "positive": "First-Principles Property Assessment of Hybrid Formate Perovskites: Hybrid organic inorganic formate perovskites, AB(HCOO)$_3$, is a large family\nof compounds which exhibit variety of phase transitions and diverse properties.\nSome examples include (anti)ferroelectricity, ferroelasticity,\n(anti)ferromagnetism, and multiferroism. While many properties of these\nmaterials have already been characterized, we are not aware of any study that\nfocuses on comprehensive property assessment of a large number of formate\nperovskites. Comparison of the materials property within the family is\nchallenging due to systematic errors attributed to different techniques or the\nlack of data. For example, complete piezoelectric, dielectric and elastic\ntensors are not available. In this work, we utilize first-principles density\nfunctional theory based simulations to overcome these challenges and to report\nstructural, mechanical, dielectric, piezoelectric, and ferroelectric properties\nfor 29 formate perovskites. We find that these materials exhibit elastic\nstiffness in the range 0.5 to 127.0 GPa , highly anisotropic linear\ncompressibility, including zero and even negative values; dielectric constants\nin the range 0.1 to 102.1; highly anisotropic piezoelectric response with the\nlongitudinal values in the range 1.18 to 21.12 pC/N, and spontaneous\npolarizations in the range 0.2 to 7.8 $\\mu$C/cm$^2$. Furthermore, we propose\nand computationally characterize a few formate perovskites, which have not been\nreported yet."
    },
    {
        "anchor": "Janus Monolayer Transition Metal Dichalcogenides: A novel crystal configuration of sandwiched S-Mo-Se structure (Janus SMoSe)\nat the monolayer limit has been synthesized and carefully characterized in this\nwork. By controlled sulfurization of monolayer MoSe2 the top layer of selenium\natoms are substituted by sulfur atoms while the bottom selenium layer remains\nintact. The peculiar structure of this new material is systematically\ninvestigated by Raman, photoluminescence and X-ray photoelectron spectroscopy\nand confirmed by transmission-electron microscopy and time-of-flight secondary\nion mass spectrometry. Density-functional theory calculations are performed to\nbetter understand the Raman vibration modes and electronic structures of the\nJanus SMoSe monolayer, which are found to correlate well with corresponding\nexperimental results. Finally, high basal plane hydrogen evolution reaction\n(HER) activity is discovered for the Janus monolayer and DFT calculation\nimplies that the activity originates from the synergistic effect of the\nintrinsic defects and structural strain inherent in the Janus structure.",
        "positive": "Hidden orders in amorphous structures: extraction of nearest neighbor\n  networks of amorphous Nd-Fe alloys with Gabriel graph analyses: Using the scheme of Delaunay and Gabriel graphs, we analyzed the amorphous\nstructures of computationally created Nd-Fe alloys for several composition\nratios based on melt quench simulations with finite temperature\nfirst-principles molecular dynamics.By the comparison of the radial\ndistribution functions of the whole system and those derived from the Delaunay\nand Gabriel graphs, it was shown that the Gabriel graphs represent the first\nnearest neighbor networks well in the examined amorphous systems. From the\nGabriel graph analyses, we examined the coordination structures of amorphous\nNd-Fe alloys statistically. We found that the ranges of distributions of\ncoordination numbers vary depending on the composition ratio. The angular\ndistributions among three adjacent atoms were also analyzed, and it was found\nthat the angular distributions behave differently in the Nd-rich and Fe-rich\nsamples. We found that the orders in the amorphous system becomes stronger as\nincreasing the Nd ratio, which corresponds to the appearance of crystalline\ngrain boundary phases at high Nd composition ratio [T. T. Sasaki et al., Acta\nMater. 115, 269-277 (2016)]."
    },
    {
        "anchor": "A comparative investigation of thickness measurements of ultra-thin\n  water films by scanning probe techniques: The reliable operation of micro and nanomechanical devices necessitates a\nthorough knowledge of the water film thickness present on the surfaces of these\ndevices with an accuracy in the nm range. In this work, the thickness of an\nultra-thin water layer was measured by distance tunnelling spectroscopy and\ndistance dynamic force spectroscopy during desorption in an ultra-high vacuum\nsystem, from about 2.5 nm up to complete desorption at 1E-8 mbar. The\ntunnelling current as well as the amplitude of vibration and the normal force\nwere detected as a function of the probe-sample distance. In these experiments,\na direct conversion of the results of both methods is possible. From the\nstandpoint of surface science, taking the state-of-the-art concerning\nadsorbates on surfaces into consideration, dynamic force spectroscopy provides\nthe most accurate values. The previously reported tunnelling spectroscopy,\nrequiring the application of significantly high voltages, generally leads to\nvalues that are 25 times higher than values determined by dynamic force\nspectroscopy.",
        "positive": "Two dimensional crystals in three dimensions: electronic decoupling of\n  single-layered platelets in colloidal nanoparticles: Two-dimensional crystals, single sheets of layered materials, often show\ndistinct properties desired for optoelectronic applications, such as larger and\ndirect band gaps, valley- and spinorbit effects. Being atomically thin, the low\namount of material is a bottleneck in photophysical and photochemical\napplications. Here, we propose the formation of stacks of two-dimensional\ncrystals intercalated with small surfactant molecules. We show, using first\nprinciples calculations, that already the very short surfactant methyl amine\nelectronically decouples the layers. We demonstrate the indirect-direct band\ngap transition characteristic for Group 6 transition metal dichalcogenides\nexperimentally by observing the emergence of a strong photoluminescence signal\nfor ethoxide-intercalated WSe2 and MoSe2 multilayered nanoparticles with\nlateral size of about 10 nm and beyond. The proposed hybrid materials offer the\nhighest possible density of the two-dimensional crystals with electronic\nproperties typical for monolayers. Variation of the surfactant's chemical\npotential allows fine-tuning of electronic properties and potentially\nelimination of trap states caused by defects."
    },
    {
        "anchor": "Time-resolved study of the magnetic field effects on electroluminescence\n  in tri-(8-hydroxyquinoline)- aluminum based organic light emitting devices: We investigated the magnetic field effects (MFEs) in organic light-emitting\ndiodes (OLEDs) through the transient electroluminescence (EL) method. The\ntime-resolved MFEs on the emission were obtained for the first time, which\nwould be a useful method to clarify the underlying mechanisms of the MFEs. The\nfluorescent dye doped tri-(8-hydroxyquinoline)-aluminum (Alq3) based OLEDs were\nfabricated. Then, the transient EL was measured both with and without a\nmagnetic field. To explore the time-resolved MFEs on the emission of the\ndevice, the excitons population dynamics in the device have been analyzed by a\nkinetic model. Our results suggest that both the intersystem crossing between\nthe singlet and triplet electron-hole pairs and the triplet-triplet\nannihilation perturbed by the external magnetic field cause the time-resolved\nMFEs.",
        "positive": "Quantitative description of short-range order and its influence on the\n  electronic structure in Ag-Pd alloys: We investigate the effect of short-range order (SRO) on the electronic\nstructure in alloys from the theoretical point of view using density of states\n(DOS) data. In particular, the interaction between the atoms at different\nlattice sites is affected by chemical disorder, which in turn is reflected in\nthe fine structure of the DOS and, hence, in the outcome of spectroscopic\nmeasurements. We aim at quantifying the degree of potential SRO with a proper\nparameter. The theoretical modeling is done with the Korringa-Kohn-Rostoker\nGreen's function method. Therein, the extended multi-sublattice non-local\ncoherent potential approximation is used to include SRO. As a model system, we\nuse the binary solid solution Ag$_c$Pd$_{1-c}$ at three representative\nconcentrations $c=0.25$, $0.5$ and $0.75$. The degree of SRO is varied from\nlocal ordering to local segregation through an intermediate completely\nuncorrelated state. We observe some pronounced features, which change over the\nwhole energy range of the valence bands as a function of SRO in the alloy.\nThese spectral variations should be traceable in modern photoemission\nexperiments."
    },
    {
        "anchor": "Optical conductivity of Bismuth-based topological insulator: The optical conductivity and the spectral weight of four topological\ninsulators with increasing chemical compensation (Bi2Se3, Bi2-xCaxSe3,\nBi2Se2Te, Bi2Te2Se) have been measured from 5 to 300 K and from sub-THz to\nvisible frequencies. The effect of compensation is clearly observed in the\ninfrared spectra, through the suppression of an extrinsic Drude term and the\nappearance of strong absorption peaks, that we assign to electronic transitions\namong localized states. From the far-infrared spectral weight of the most\ncompensated sample (Bi2Te2Se) one can estimate a density of charge-carriers in\nthe order of 10^17/cm^3 in good agreement with transport data. Those results\ndemonstrate that the low-energy electrodynamics in single crystals of\ntopological insulators, even at the highest degree of compensation presently\nachieved, is still affected by extrinsic charge excitations.",
        "positive": "Unipolar resistive switching in cobalt titanate thin films: We report giant resistive switching of an order of 104, long-time charge\nretention characteristics up to 104 s, non-overlapping SET and RESET voltages,\nohmic in low resistance state (LRS) and space charge limited current (SCLC)\nmechanism in high resistance state (HRS) properties in polycrystalline\nperovskite Cobalt Titanate (CoTiO3 ~ CTO) thin films. Impedance spectroscopy\nstudy was carried out for both LRS and HRS states which illustrates that only\nbulk resistance changes after resistance switching, however, there is a small\nchange (<10% which is in pF range) in the bulk capacitance value in both\nstates. These results suggest that in LRS state current filaments break the\ncapacitor in many small capacitors in a parallel configuration which in turn\nprovides the same capacitance in both states even there was 90 degree changes\nin phase-angle and an order of change in the tangent loss."
    },
    {
        "anchor": "An Atomistic Modelling Framework for Valence Change Memory Cells: We present a framework dedicated to modelling the resistive switching\noperation of Valence Change Memory (VCM) cells. The method combines an\natomistic description of the device structure, a Kinetic Monte Carlo (KMC)\nmodel for the creation and diffusion of oxygen vacancies in the central oxide\nunder an external field, and an ab-initio quantum transport method to calculate\nelectrical current and conductance. As such, it reproduces a realistically\nstochastic device operation and its impact on the resulting conductance. We\ndemonstrate this framework by simulating a switching cycle for a\nTiN/HfO$_2$/TiN VCM cell, and see a clear current hysteresis between high/low\nresistance states, with a conductance ratio of one order of magnitude.\nAdditionally, we observe that the changes in conductance originate from the\ncreation and recombination of vacancies near the active electrode, effectively\nmodulating a tunnelling gap for the current. This framework can be used to\nfurther investigate the mechanisms behind resistive switching at an atomistic\nscale and optimize VCM material stacks and geometries.",
        "positive": "Bulk and nano GaN: Role of Ga d states: We have studied the role of Ga 3d states in determining the properties of\nbulk as well as nanoparticles of GaN using PAW potentials. A significant\ncontribution of the Ga d states in the valence band is found to arise from the\ninteraction of Ga 4d states with the dominantly N p states making up the\nvalence band. The errors arising from not treating the Ga 3d states as a part\nof the valence are found to be similar, ~ 1%, for bulk as well as for\nnanoclusters of GaN."
    },
    {
        "anchor": "Molecular dynamics simulations of oxide memristors: crystal field\n  effects: We present molecular-dynamic simulations of memory resistors (memristors)\nincluding the crystal field effects on mobile ionic species such as oxygen\nvacancies appearing during operation of the device. Vacancy distributions show\ndifferent patterns depending on the ratio of a spatial period of the crystal\nfield to a characteristic radius of the vacancy-vacancy interaction. There are\nsignatures of the orientational order and of spatial voids in the vacancy\ndistributions for some crystal field potentials. The crystal field stabilizes\nthe patterns after they are formed, resulting in a non-volatile switching of\nthe simulated devices.",
        "positive": "Ice : The paradigm of wild plasticity: Ice plasticity has been thoroughly studied, owing to its importance in\nglaciers and ice sheets dynamics. In particular, its anisotropy (easy basal\nslip) has been suspected for a long time, then fully characterized 40 years\nago. More recently emerged the interest of ice as a model material to study\nsome fundamental aspects of crystalline plasticity. An example is the nature of\nplastic fluctuations and collective dislocation dynamics. 20 years ago,\nacoustic emission measurements performed during the deformation of ice single\ncrystals revealed that plastic flow proceeds through intermittent dislocation\navalanches, power law distributed in size and energy. This means that most of\nice plasticity takes place through few, very large avalanches, thus qualifying\nassociated plastic fluctuations as wild. This launched an intense research\nactivity on plastic intermittency in the Material Science community. The\ninterest of ice in this debate is reviewed, from a comparison with other\ncrystalline materials. In this context, ice appears as an extreme case of\nplastic intermittency, characterized by scale-free fluctuations, complex space\nand time correlations as well as avalanche triggering. In other words, ice can\nbe considered as the paradigm of wild plasticity."
    },
    {
        "anchor": "Quasiparticle and Optical Properties of Rutile and Anatase TiO$_{2}$: Quasiparticle excitation energies and optical properties of TiO$_{2}$ in the\nrutile and anatase structures are calculated using many-body perturbation\ntheory methods. Calculations are performed for a frozen crystal lattice;\nelectron-phonon coupling is not explicitly considered. In the GW method,\nseveral approximations are compared and it is found that inclusion of the full\nfrequency dependence as well as explicit treatment of the Ti semicore states\nare essential for accurate calculation of the quasiparticle energy band gap.\nThe calculated quasiparticle energies are in good agreement with available\nphotoemission and inverse photoemission experiments. The results of the GW\ncalculations, together with the calculated static screened Coulomb interaction,\nare utilized in the Bethe-Salpeter equation to calculate the dielectric\nfunction $\\epsilon_{2}(\\omega)$ for both the rutile and anatase structures. The\nresults are in good agreement with experimental observations, particularly the\nonset of the main absorption features around 4 eV. For comparison to low\ntemperature optical absorption measurements that resolve individual excitonic\ntransitions in rutile, the low-lying discrete excitonic energy levels are\ncalculated with electronic screening only. The lowest energy exciton found in\nthe energy gap of rutile has a binding energy of 0.13 eV. In agreement with\nexperiment, it is not dipole allowed, but the calculated exciton energy exceeds\nthat measured in absorption experiments by about 0.22 eV and the scale of the\nexciton binding energy is also too large. The quasiparticle energy alignment of\nrutile is calculated for non-polar (110) surfaces. In the GW approximation, the\nvalence band maximum is 7.8 eV below the vacuum level, showing a small shift\nfrom density functional theory results.",
        "positive": "Meta-analysis of literature data in metal additive manufacturing: What\n  can we (and the machine) learn from reported data?: Obtaining in-depth understanding of the relationships between the additive\nmanufacturing (AM) process, microstructure and mechanical properties is crucial\nto overcome barriers in AM. In this study, database of metal AM was created\nthanks to many literature studies. Subsequently meta-analyses on the data was\nundertaken to provide insights into whether such relationships are well\nreflected in the literature data. The analyses help reveal the bias and what\nthe data tells us, and to what extent machine learning (ML) can learn from the\ndata. The first major bias is associated with common practices in identifying\nthe process based on optimizing the consolidation. Most reports were for\nconsolidation while data on microstructure and mechanical properties was\nsignificantly less. In addition, only high consolidation values was provided,\nso ML was not able to learn the full spectrum of the process - consolidation\nrelationship. The common identification of process maps based on only\nconsolidation also poses another bias as mechanical properties that ultimately\ngovern the quality of an AM build are controlled not only by the consolidation,\nbut also microstructure. Meta-analysis of the literature data also shows weak\ncorrelation between process with consolidation and mechanical properties. This\nweak correlation is attributed to the stated biases and the non-monotonic and\nnon-linear relationships between the process and quality variables.\nFortunately, trained ML models capture well the influence and interactions\nbetween process parameters and quality variables, and predicts accurately the\nyield stress, suggesting that the correlation between process, microstructure\nand yield strength is well reflected in the data. Lastly, due to the current\nlimitation in the process map identification, we propose to identify the\nprocess map based on not only the consolidation, but also mechanical\nproperties."
    },
    {
        "anchor": "Band-Like Electron Transport in Organic Transistors and Implication of\n  the Molecular Structure for Performance Optimization: Single-crystal organic field-effect transistors (OFETs) based on p-channel\nmolecular semiconductors have led to breakthrough carrier mobilities and to the\nobservation of band-like transport. These results represent the limit in our\nquest for the ultimate OFET performance. However, band-like transport has not\nbeen reported for n-channel OFETs and, for p-channel transistors, it is not\nunderstood why it occurs only for certain molecular materials. Here we report\nband-like electron transport for n-channel OFETs based on PDIF-CN2\nsingle-crystals. Devices with different gate dielectrics - vacuum, Cytop, PMMA\n- are compared and we find that the performance is suppressed for those with\nlarger dielectric constant. This phenomenon parallels that observed for holes\nin p-channel OFETs, however, the magnitude of the suppression is smaller, an\neffect that can be rationalized by the semiconductor molecular structure and\ncrystal packing. A quantitative analysis of our findings, together with results\non different high-quality p-channel transistors, indicates the importance of\nthe interplay between the semiconductor molecular polarizability and the\nstructure of the charge transport layers in the crystal, as a key factor\nenabling band-like transport. Based on these considerations, we suggest\nunprecedented structure-property relationships useful for performance\noptimization of high-mobility organic transistors.",
        "positive": "Effects of the Position Reversal of Friction Pairs on the Strength of\n  Tribocharging and Tribodischarging: The friction-induced charging (i.e., tribocharging) and the following\ndischarging (referred here as tribodischarging) are always believed to have\nnegative effects on the daily life and on the industrial production. Thus, how\nto inhibit the tribocharging and the tribodischarging has caused wide public\nconcern. Because the discharge caused by the electrical breakdown of the\nambient gas is generally accompanied with the generation of light, we\ninvestigated here the tribocharging and the tribodischarging by observing the\nlight emitted during friction. We found that the position reversal of the\nfriction pair has a dramatic impact on the intensity of the tribo-induced\nlight. Experimental results show that an intense light is produced when a\nstationary Al2O3 disk is sliding on a rotating SiO2 disk, but only a weak light\nis observed for the case of a stationary SiO2 disk and a rotating Al2O3 disk.\nThis means that the process of the tribocharging and the tribodischarging can\nbe significantly influenced owing to the change in the relative position of the\nfriction couple. The experimentally measured polarities of the tribo-induced\ncharge on the friction surfaces further indicated that the strong discharging\noccurs when the rotating surface is negatively charged. The reason for the\ndifference in the intensity of the tribocharging and tribodischarging can be\nattributed to the combined effects of the contact potential difference and the\ntemperature gradient between the contacting surfaces on the charge transfer\nwhen friction. Finally, a simple, low cost, yet effective approach, i.e., just\nkeep the friction partner whose surface is tribo-induced negatively charged as\nthe stationary one, can be utilized to suppress the intensity of the\ntribocharging and the tribodischarging. This work may provide potential\napplications in numerous areas of science and engineering and also in the\neveryday life."
    },
    {
        "anchor": "N\u00e9el-type skyrmion in WTe2/Fe3GeTe2 van der Waals heterostructure: The promise of high-density and low-energy-consumption devices motivates the\nsearch for layered structures that stabilize chiral spin textures such as\ntopologically protected skyrmions. At the same time, layered structures provide\na new platform for the discovery of new physics and effects. Recently\ndiscovered long-range intrinsic magnetic orders in the two-dimensional van der\nWaals materials offer new opportunities. Here we demonstrate the\nDzyaloshinskii-Moriya interaction and N\\'eel-type skyrmions are induced at the\nWTe2/Fe3GeTe2 interface. Fe3GeTe2 is a ferromagnetic material with strong\nperpendicular magnetic anisotropy. We demonstrate that the strong spin orbit\ninteraction in 1T'-WTe2 does induce a large interfacial Dzyaloshinskii-Moriya\ninteraction at the interface with Fe3GeTe2 due to the inversion symmetry\nbreaking to stabilize skyrmions. Transport measurements show the topological\nHall effect in this heterostructure for temperatures below 100 K. Furthermore,\nLorentz transmission electron microscopy is used to directly image N\\'eel-type\nskyrmions along with aligned and stripe-like domain structure. This interfacial\ncoupling induced Dzyaloshinskii-Moriya interaction is estimated to have a large\nenergy of 1.0 mJ/m^2, which can stabilize the N\\'eel-type skyrmions in this\nheterostructure. This work paves a path towards the skyrmionic devices based on\nvan der Waals heterostructures.",
        "positive": "Optical absorption spectra of finite systems from a conserving\n  Bethe-Salpeter equation approach: We present a method for computing optical absorption spectra by means of a\nBethe-Salpeter equation approach, which is based on a conserving linear\nresponse calculation for electron-hole coherences in the presence of an\nexternal electromagnetic field. This procedure allows, in principle, for the\ndetermination of the electron-hole correlation function self-consistently with\nthe corresponding single-particle Green function. We analyze the general\napproach for a \"one-shot\" calculation of the photoabsorption cross section of\nfinite systems, and discuss the importance of scattering and dephasing\ncontributions in this approach. We apply the method to the closed-shell\nclusters Na_4, Na^+_9 and Na^+_(21), treating one active electron per Na atom."
    },
    {
        "anchor": "The influence of surface stress on the equilibrium shape of strained\n  quantum dots: The equilibrium shapes of InAs quantum dots (i.e., dislocation-free, strained\nislands with sizes >= 10,000 atoms) grown on a GaAs (001) substrate are studied\nusing a hybrid approach which combines density functional theory (DFT)\ncalculations of microscopic parameters, surface energies, and surface stresses\nwith elasticity theory for the long-range strain fields and strain relaxations.\nIn particular we report DFT calculations of the surface stresses and analyze\nthe influence of the strain on the surface energies of the various facets of\nthe quantum dot. The surface stresses have been neglected in previous studies.\nFurthermore, the influence of edge energies on the island shapes is briefly\ndiscussed. From the knowledge of the equilibrium shape of these islands, we\naddress the question whether experimentally observed quantum dots correspond to\nthermal equilibrium structures or if they are a result of the growth kinetics.",
        "positive": "Wannier Functions Dually Localized in Space and Energy: Wannier functions are real-space representations of Bloch orbitals that\nprovide a useful picture for chemical bonding and offer a localized description\nof single-particle wave functions. There is a unitary freedom in the\nconstruction of Wannier functions from Bloch orbitals, which can be chosen to\nproduce Wannier functions that have advantageous properties. A popular choice\nfor this freedom is the minimization of spatial variance, which leads to\nmaximally localized Wannier functions. We minimize a weighted sum of the\nspatial and energy variances, yielding what we call dually localized Wannier\nfunctions. Localization in energy results in Wannier functions that are\nassociated with a particular energy and allows for dually localized Wannier\nfunctions to be comprised of occupied and unoccupied spaces simulatneously.\nThis can lead to Wannier functions that are fractionally occupied, which is a\nkey feature that is used in correcting the delocalization error in density\nfunctional approximations. We show how this type of localization results in\nbonding (antibonding) functions for the occupied (unoccupied) spaces around the\nfrontier energy of silicon in the diamond lattice and of molecular ethylene.\nDually localized Wannier functions therefore offer a relevant description for\nchemical bonding and are well suited to orbital-dependent methods that\nassociate Wannier functions with specific energy ranges without the need to\nconsider the occupied and unoccupied spaces separately."
    },
    {
        "anchor": "Direct observation and temperature control of the surface Dirac gap in\n  the topological crystalline insulator (Pb,Sn)Se: Since the advent of topological insulators hosting symmetry-protected Dirac\nsurface states, efforts have been made to gap these states in a controllable\nway. A new route to accomplish this was opened up by the discovery of\ntopological crystalline insulators (TCIs) where the topological states are\nprotected by real space crystal symmetries and thus prone to gap formation by\nstructural changes of the lattice. Here, we show for the first time a\ntemperature-driven gap opening in Dirac surface states within the TCI phase in\n(Pb,Sn)Se. By using angle-resolved photoelectron spectroscopy, the gap\nformation and mass acquisition is studied as a function of composition and\ntemperature. The resulting observations lead to the addition of a temperature-\nand composition-dependent boundary between massless and massive Dirac states in\nthe topological phase diagram for (Pb,Sn)Se (001). Overall, our results\nexperimentally establish the possibility to tune between a massless and massive\ntopological state on the surface of a topological system.",
        "positive": "Design of soft magnetic materials: We present a strategy for the design of ferromagnetic materials with\nexceptionally low magnetic hysteresis, quantified by coercivity. In this\nstrategy, we use a micromagnetic algorithm that we have developed in previous\nresearch and which has been validated by its success in solving the \"Permalloy\nProblem\" -- the well-known difficulty of predicting the composition 78.5% Ni of\nlowest coercivity in the Fe-Ni system -- and by the insight, it provides into\nthe \"Coercivity Paradox\" of W. F. Brown. Unexpectedly, the design strategy\npredicts that cubic materials with large saturation magnetization $m_s$ and\nlarge magnetocrystalline anisotropy constant $\\kappa_1$ will have low\ncoercivity on the order of that of Permalloy, as long as the magnetostriction\nconstants $\\lambda_{100}, \\lambda_{111}$ are tuned to special values. The\nexplicit prediction for a cubic material with low coercivity is the\ndimensionless number $(c_{11}-c_{12}) \\lambda_{100}^2/\\kappa_1 = 81$ for\n$\\langle 100 \\rangle$ easy axes. The results would seem to have a broad\npotential application, especially to magnetic materials of interest in energy\nresearch."
    },
    {
        "anchor": "Pd magnetism induced by indirect interlayer exchange coupling: We show that very large paramagnetic moments are created in ultrathin Pd\nlayers through indirect interlayer exchange coupling. Pd $L$-edge x-ray\nmagnetic circular dichroism measurements show Pd moments in\n[Pd(2.5nm)/Cu(3nm)/Ni$_{81}$Fe$_{19}$(5nm)/Cu(3nm)]$_{20}$ superlattices which\nare ferromagnetically aligned with the applied field and nearly 3% the size of\nPd moments created in directly exchange coupled\n[Pd(2.5nm)/Ni$_{81}$Fe$_{19}$(5nm)]$_{20}$ superlattices. The induced moment is\ntwo orders of magnitude larger than that expected from RKKY exchange acting on\nthe bulk paramagnetic susceptibility of Pd.",
        "positive": "Edge Disorder in Bottom-Up Zigzag Graphene Nanoribbons: Implications for\n  Magnetism and Quantum Electronic Transport: We unveil the nature of the structural disorder in bottom-up zigzag graphene\nnanoribbons along with its effect on the magnetism and electronic transport on\nthe basis of scanning probe microscopies and first-principles calculations. We\nfind that edge-missing m-xylene units emerging during the cyclodehydrogenation\nstep of the on-surface synthesis are the most common point defects. These\n\"bite'' defects act as spin-1 paramagnetic centers, severely disrupt the\nconductance spectrum around the band extrema, and give rise to spin-polarized\ncharge transport. We further show that the electronic conductance across\ngraphene nanoribbons is more sensitive to \"bite\" defects forming at the zigzag\nedges than at the armchair ones. Our work establishes a comprehensive\nunderstanding of the low-energy electronic properties of disordered bottom-up\ngraphene nanoribbons."
    },
    {
        "anchor": "Electroforming Free Controlled Bipolar Resistive Switching in\n  Al/CoFe2O4/FTO device with Self-Compliance Effect: Controlled bipolar resistive switching (BRS) has been observed in\nnanostructured CoFe2O4 films using Al(aluminum)/CoFe2O4/FTO(fluorine-doped tin\noxide) device. The fabricated device shows electroforming-free uniform BRS with\ntwo clearly distinguished and stable resistance states without any application\nof compliance current (CC), with a resistance ratio of high resistance state\n(HRS) and low resistance state (LRS) > 102. Small switching voltage (< 1 volt)\nand lower current in both the resistance states confirms the fabrication of low\npower consumption device. In the LRS, the conduction mechanism was found to be\nof Ohmic in nature, while the high-resistance state (HRS/OFF state) was\ngoverned by space charge-limited conduction mechanism, which indicates the\npresence of an interfacial layer with imperfect microstructure near the top\nAl/CFO interface. The device shows nonvolatile behavior with good endurance\nproperties, acceptable resistance ratio, uniform resistive switching due to\nstable, less random filament formation/rupture and a control over the resistive\nswitching properties by choosing different stop voltages, which makes the\ndevice suitable for its application in future nonvolatile resistive random\naccess memory (ReRAM).",
        "positive": "Toward the use of temporary tattoo electrodes for impedancemetric\n  respiration monitoring and other electrophysiological recordings: Development of dry, ultra-conformable and unperceivable temporary tattoo\nelectrodes (TTEs), based on the ink-jet printing of PEDOT:PSS on top of\ncommercially available temporary tattoo paper, has gained increasing attention\nas a new and promising technology for electrophysiological recordings on skin.\nIn this work we present a TTEs epidermal sensor for real time monitoring of\nrespiration through transthoracic impedance measurements, exploiting a new\ndesign based on the application of soft screen printed Ag ink and magnetic\ninterlink, that guarantees a repositionable, long term stable and robust\ninterconnection of TTEs with external docking devices. The efficiency of the\nTTE and the proposed interconnection strategy under stretching (up to 10%) and\nover time (up to 96 hours) has been verified on a dedicated experimental setup\nand on humans, fulfilling the proposed specific application of transthoracic\nimpedance measurements. The proposed approach makes this technology suitable\nfor large-scale production and suitable not only for the specific use case\npresented, but also for real time monitoring of different bio-electric signals,\nas demonstrated through specific proof of concept demonstrators."
    },
    {
        "anchor": "Optical alignment and polarization conversion of neutral exciton spin in\n  individual InAs/GaAs quantum dots: We investigate exciton spin memory in individual InAs/GaAs self-assembled\nquantum dots via optical alignment and conversion of exciton polarization in a\nmagnetic field. Quasiresonant phonon-assisted excitation is successfully\nemployed to define the initial spin polarization of neutral excitons. The\nconservation of the linear polarization generated along the bright exciton\neigenaxes of up to 90% and the conversion from circular- to linear polarization\nof up to 47% both demonstrate a very long spin relaxation time with respect to\nthe radiative lifetime. Results are quantitatively compared with a model of\npseudo-spin 1/2 including heavy-to-light hole mixing.",
        "positive": "An enthalpy-based multiple-relaxation-time lattice Boltzmann method for\n  solid-liquid phase change heat transfer in metal foams: In this paper, an enthalpy-based multiple-relaxation-time (MRT) lattice\nBoltzmann (LB) method is developed for solid-liquid phase change heat transfer\nin metal foams under local thermal non-equilibrium (LTNE) condition. The\nenthalpy-based MRT-LB method consists of three different MRT-LB models: one for\nflow field based on the generalized non-Darcy model, and the other two for\nphase change material (PCM) and metal foam temperature fields described by the\nLTNE model. The moving solid-liquid phase interface is implicitly tracked\nthrough the liquid fraction, which is simultaneously obtained when the energy\nequations of PCM and metal foam are solved. The present method has several\ndistinctive features. First, as compared with previous studies, the present\nmethod avoids the iteration procedure, thus it retains the inherent merits of\nthe standard LB method and is superior over the iteration method in terms of\naccuracy and computational efficiency. Second, a volumetric LB scheme instead\nof the bounce-back scheme is employed to realize the no-slip velocity condition\nin the interface and solid phase regions, which is consistent with the actual\nsituation. Last but not least, the MRT collision model is employed, and with\nadditional degrees of freedom, it has the ability to reduce the numerical\ndiffusion across phase interface induced by solid-liquid phase change.\nNumerical tests demonstrate that the present method can be served as an\naccurate and efficient numerical tool for studying metal foam enhanced\nsolid-liquid phase change heat transfer in latent heat storage. Finally,\ncomparisons and discussions are made to offer useful information for practical\napplications of the present method."
    },
    {
        "anchor": "Surface scaling behaviour of size-selected Ag-nanocluster film growing\n  under subsequent shadowing process: Surface morphology of size-selected silver nanocluster films grown by dc\nmagnetron sputtering has been investigated by means of an atomic force\nmicroscopy (AFM). From the height-height correlation functions ( HHCF) obtained\nfrom corresponding AFM images, the scaling exponents are calculated and two\ntypes of growth regimes have been observed. In the first regime, the growth\nexponent is found to be \\b{eta}1 = 0.27\\pm0.07 close to the KPZ growth\nexponent, while in the second growth regime shadowing effect plays dominant\nrole which gives the growth exponent value \\b{eta}2 = 0.88\\pm0.28. On the other\nhand for the whole deposition regime, the roughness exponent value is found to\nbe constant around {\\alpha}= 0.76\\pm0.02. UV-vis spectroscopy measurement\nsuggests how the average reflectance of the film surface changes with different\ngrowth times.",
        "positive": "Experimental formation of monolayer group-IV monochalcogenides: Monolayer group-IV monochalcogenides (MX, M = Ge, Sn, Pb; X = S, Se, Te) are\na family of novel two-dimensional (2D) materials that have atomic structures\nclosely related to that of the staggered black phosphorus lattice. The\nstructure of most monolayer MX materials exhibits a broken inversion symmetry,\nand many of them exhibit ferroelectricity with a reversible in-plane electric\npolarization. A further consequence of the noncentrosymmetric structure is that\nwhen coupled with strong spin-orbit coupling, many MX materials are promising\nfor the future applications in non-linear optics, photovoltaics, spintronics\nand valleytronics. Nevertheless, because of the relatively large exfoliation\nenergy, the creation of monolayer MX materials is not easy, which hinders the\nintegration of these materials into the fast-developing field of 2D material\nheterostructures. In this Perspective, we review recent developments in\nexperimental routes to the creation of monolayer MX, including molecular beam\nepitaxy and two-step etching methods. Other approaches that could be used to\nprepare monolayer MX are also discussed, such as liquid phase exfoliation and\nsolution phase synthesis. A quantitative comparison between these different\nmethods is also presented."
    },
    {
        "anchor": "Gas sensing technologies -- status, trends, perspectives and novel\n  applications: The strong, continuous progresses in gas sensors and electronic noses\nresulted in improved performance and enabled an increasing range of\napplications with large impact on modern societies, such as environmental\nmonitoring, food quality control and diagnostics by breath analysis. Here we\nreview this field with special attention to established and emerging approaches\nas well as the most recent breakthroughs, challenges and perspectives. In\nparticular, we focus on (1) the transduction principles employed in different\narchitectures of gas sensors, analysing their advantages and limitations; (2)\nthe sensing layers including recent trends toward nanostructured,\nlow-dimensional and composite materials; (3) advances in signal processing\nmethodologies, including the recent advent of artificial neural networks.\nFinally, we conclude with a summary on the latest achievements and trends in\nterms of applications.",
        "positive": "Creation of Single Chain of Nanoscale Skyrmion Bubbles with Record-high\n  Temperature Stability in a Geometrically Confined Nanostripe: Nanoscale topologically non-trivial spin textures, such as magnetic\nskyrmions, have been identified as promising candidates for the transport and\nstorage of information for spintronic applications, notably magnetic racetrack\nmemory devices. The design and realization of single skyrmion chain at room\ntemperature (RT) and above in the low-dimensional nanostructures are of great\nimportance for future practical applications. Here, we report the creation of a\nsingle skyrmion bubble chain in a geometrically confined Fe3Sn2 nanostripe with\na width comparable to the featured size of a skyrmion bubble. Systematic\ninvestigations on the thermal stability have revealed that the single chain of\nskyrmion bubbles can keep stable at temperatures varying from RT up to a\nrecord-high temperature of 630 K. This extreme stability can be ascribed to the\nweak temperature-dependent magnetic anisotropy and the formation of edge states\nat the boundaries of the nanostripes. The realization of the highly stable\nskyrmion bubble chain in a geometrically confined nanostructure is a very\nimportant step towards the application of skyrmion-based spintronic devices."
    },
    {
        "anchor": "Insight into the interface between Fe$_3$O$_4$(001) surface and water\n  overlayers through multiscale molecular dynamics simulations: In this work we investigate the Fe$_3$O$_4$(001) surface/water interface by\ncombining several theoretical approaches, ranging from a hybrid functional\nmethod (HSE06) to density-functional tight-binding (DFTB) to molecular\nmechanics (MM). First, we assess the accuracy of the DFTB method to reproduce\ncorrectly HSE06 results on structural details and energetics and available\nexperimental data for the adsorption of isolated water, dimers, trimers, etc.\nup to a water monolayer. Secondly, we build two possible configurations of a\nsecond and a third overlayer and perform molecular dynamics simulations with\nDFTB, monitoring the water orientation, the H-bond network, and ordered water\nstructures formation. To make our models more realistic, we then build a 12-nm\nthick water multilayer on top of the Fe$_3$O$_4$(001) surface slab model, which\nwe investigate through MM molecular dynamics. The water layers structuring,\nrevealed by the analysis of the atomic positions from a long MM-MD run for this\nlarge MM model, extends up to about 6-7 {\\AA} and nicely compares with that\nobserved for a water trilayer model. However, MM and DFTB MD simulations show\nsome discrepancy due to the poor description of the Fe--OH2 distance in MM that\ncalls for further work in the parametrization of the model.",
        "positive": "Does cluster encapsulation inhibit sintering? Stabilization of\n  size-selected Pt clusters on Fe$_3$O$_4$(001) by SMSI: The metastability of supported metal nanoparticles limits their application\nin heterogeneous catalysis at elevated temperatures due to their tendency to\nsinter. One strategy to overcome these thermodynamic limits on reducible oxide\nsupports is encapsulation via strong metal-support interaction (SMSI). While\nannealing-induced encapsulation is a well-explored phenomenon for extended\nnanoparticles, it is as yet unknown whether the same mechanisms hold for\nsub-nanometer clusters, where concomitant sintering and alloying might play a\nsignificant role. In this article, we explore the encapsulation and stability\nof size-selected Pt$_5$, Pt$_{10}$ and Pt$_{19}$ clusters deposited on\nFe$_3$O$_4$(001). In a multimodal approach using temperature-programmed\ndesorption (TPD), x-ray photoelectron spectroscopy (XPS) and scanning tunneling\nmicroscopy (STM), we demonstrate that SMSI indeed leads to the formation of a\ndefective, FeO-like conglomerate encapsulating the clusters. By stepwise\nannealing up to 1023 K, we observe the succession of encapsulation, cluster\ncoalescence and Ostwald ripening, resulting in square-shaped crystalline Pt\nparticles, independent of the initial cluster sizes. The respective sintering\nonset temperatures scale with the cluster footprint and thus size. Remarkably,\nwhile small encapsulated clusters can still diffuse as a whole, atom detachment\nand thus Ostwald ripening are successfully suppressed up to 823 K, i.e. 200 K\nabove the H\\\"uttig temperature that indicates the thermodynamic stability\nlimit."
    },
    {
        "anchor": "Trends in elastic properties of Ti-Ta alloys from first-principles\n  calculations: The martensitic start temperature ($M_{\\text{s}}$) is a technologically\nfundamental characteristic of high-temperature shape memory alloys. We have\nrecently shown [Phys. Rev. B 94, 224104 (2016)] that the two key features in\ndescribing the composition dependence of $M_\\text{s}$ are the $T=0$ K phase\nstability and the difference in vibrational entropy which, within the Debye\nmodel, is directly linked to the elastic properties. Here, we use density\nfunctional theory together with special quasi-random structures to study the\nelastic properties of disordered martensite and austenite Ti-Ta alloys as a\nfunction of composition. We observe a softening in the tetragonal shear elastic\nconstant of the austenite phase at low Ta content and a \\emph{non-linear}\nbehavior in the shear elastic constant of the martensite. A minimum of 12.5$\\%$\nTa is required to stabilize the austenite phase at $T = 0$ K. Further, the\nshear elastic constants and Young's modulus of martensite exhibit a maximum for\nTa concentrations close to 30$\\%$. Phenomenological, elastic-constant-based\ncriteria suggest that the addition of Ta enhances the strength, but reduces the\nductile character of the alloys. In addition, the directional elastic\nstiffness, calculated for both martensite and austenite, becomes more isotropic\nwith increasing Ta content. The reported trends in elastic properties as a\nfunction of composition may serve as a guide in the design of alloys with\noptimized properties in this interesting class of materials.",
        "positive": "Leakage-free electrolytes with different conductivity for non-volatile\n  memory device utilizing insulator/metal ferromagnet transition of SrCoOx: The electrochemical switching of SrCoOx-based non-volatile memory with\nthin-film-transistor structure was examined by using liquid-leakage-free\nelectrolytes with different conductivity (s) as the gate insulator. We first\nexamined leakage-free water, which is incorporated in the amorphous (a-) 12CaO\n7Al2O3 film with nanoporous structure (CAN), but the electrochemical\noxidation/reduction of SrCoOx layer required the application of high gate\nvoltage (Vg) up to 20 V for a very long retention-time (t) 40 minutes,\nprimarily due to the low s (2.0 x 10-8 S cm-1 at RT) of leakage-free water.We\nthen controlled the s of leakage-free electrolyte, infiltrated in the a-NaxTaO3\nfilm with nanopillar array structure, from 8.0 x 10-8 S cm-1 to 2.5 x 10-6 S\ncm-1 at RT by changing the x = 0.01-1.0. As the result, the t, required for the\nmetallization of SrCoOx layer under small Vg = -3 V, becomes two orders of\nmagnitude shorter with increase of the s of the a-NaxTaO3 leakage-free\nelectrolyte. These results indicate that the ion migration in the leakage-free\nelectrolyte is the rate-determining step for the electrochemical switching,\ncompared to the other electrochemical process, and the high s of the\nleakage-free electrolyte is the key factor for the development of the\nnon-volatile SrCoOx-based electro-magnetic phase switching device."
    },
    {
        "anchor": "Strain assisted magnetization switching in ordered nanomagnets of\n  CoFe2O4/SrRuO3/PMNPT hetrostructures: We have explored the electric field controlled magnetization in the nanodot\nCoFe2O4/SrRuO3/PMN-PT heterostructures. Ordered ferromagnetic CFO nanodots\n(~300 nm lateral dimension) are developed on the PMN-PT substrate\n(ferroelectric as well as piezoelectric) using a nanostencil-mask pattering\nmethod during pulsed laser deposition. The nanostructures reveal electric field\ninduced magnetization reversal in the single domain CFO nanodots through\ntransfer of piezostrains from the piezoelectric PMN-PT substrate to the CFO.\nFurther, electric field modulated spin structure of CFO nanomagnets is analysed\nby using X-ray magnetic circular dichroism (XMCD). The XMCD analysis reveals\ncations (Fe3+/Co2+) redistribution on the octahedral and tetrahedral site in\nthe electric field poled CoFe2O4 nanodots, establishing the strain induced\nmagneto-electric coupling effects. The CoFe2O4/SrRuO3/PMN-PT nanodots structure\ndemonstrate multilevel switching of ME coupling coefficient ({\\alpha}) by\napplying selective positive and negative electric fields in a non-volatile\nmanner. The retention of two stable states of {\\alpha} is illustrated for ~106\nseconds, which can be employed to store the digital data in non-volatile memory\ndevices. Thus the voltage controlled magnetization in the nanodot structures\nleads a path towards the invention of energy efficient high-density memory\ndevices.",
        "positive": "Nonmonotonic magnetic field dependence of remanent ferroelectric\n  polarization in reduced-graphene-oxide-BiFeO$_3$ nanocomposite: In a nanocomposite of reduced graphene oxide (RGO) and BiFeO$_3$ (BFO), the\nremanent ferroelectric polarization is found to follow nonmonotonic magnetic\nfield dependence at room temperature as the applied magnetic field is swept\nacross 0-20 kOe on a pristine sample. The remanent ferroelectric polarization\nis determined both from direct electrical measurements on an assembly of\nnanoparticles and powder neutron diffraction patterns recorded under 0-20 kOe\nfield. The nanosized ($\\sim$20 nm) particles of BFO are anchored onto the\ngraphene sheets of RGO via Fe-C bonds with concomitant rise in covalency in the\nFe-O bonds. The field-dependent competition between the positive and negative\nmagnetoelectric coupling arising from magnetostriction due to, respectively,\ninterface and bulk magnetization appears to be giving rise to the observed\nnonmonotonic field dependence of polarization. The emergence of Fe-C bonds and\nconsequent change in the magnetic and electronic structure of the interface\nregion has influenced the coupling between ferroelectric and magnetic\nproperties remarkably and thus creates a new way of tuning the magnetoelectric\nproperties via reconstruction of interfaces in nanocomposites or\nheterostructures of graphene/single-phase-multiferroic systems."
    },
    {
        "anchor": "Electronic, Magnetic and Vibrational Properties of Single Layer Aluminum\n  Oxide: The structural, magnetic, vibrational and electronic properties of single\nlayer aluminum oxide (AlO2) are investigated by performing state-of-the-art\nfirst-principles calculations. Total energy optimization and phonon\ncalculations reveal that aluminum oxide forms a distorted octahedral structure\n(1T'-AlO2) in its single layer limit. It is also shown that surfaces of\n1T'-AlO2 display magnetic behavior originating from the O atoms. While the\nferromagnetic (FM) state is the most favorable magnetic order for 1T'-AlO2,\ntransformation to a dynamically stable antiferromagnetic (AFM) state upon a\nslight distortion in the crystal structure is also possible. It is also shown\nthat Raman activities (350-400 cm^-1) obtained from the vibrational spectrum\ncan be utilized to distinguish the possible magnetic phases of the crystal\nstructure. Electronically, both FM and the AFM phases are semiconductors with\nan indirect band gap and they can form a type-III vdW heterojunction with\ngraphene-like ultra-thin materials. Moreover, it is predicted that presence of\noxygen defects that inevitably occur during synthesis and production do not\nalter the magnetic state, even at high vacancy density. Apparently, ultra-thin\n1T'-AlO2 with its stable crystal structure, semiconducting nature and robust\nmagnetic state is a quite promising material for nanoscale device applications.",
        "positive": "A High-Resolution Compton Scattering Study of the Electron Momentum\n  Density in Al: We report high-resolution Compton profiles (CP's) of Al along the three\nprincipal symmetry directions at a photon energy of 59.38 keV, together with\ncorresponding highly accurate theoretical profiles obtained within the\nlocal-density approximation (LDA) based band-theory framework. A good accord\nbetween theory and experiment is found with respect to the overall shapes of\nthe CP's, their first and second derivatives, as well as the anisotropies in\nthe CP's defined as differences between pairs of various CP's. There are\nhowever discrepancies in that, in comparison to the LDA predictions, the\nmeasured profiles are lower at low momenta, show a Fermi cutoff which is\nbroader, and display a tail which is higher at momenta above the Fermi\nmomentum. A number of simple model calculations are carried out in order to\ngain insight into the nature of the underlying 3D momentum density in Al, and\nthe role of the Fermi surface in inducing fine structure in the CP's. The\npresent results when compared with those on Li show clearly that the size of\ndiscrepancies between theoretical and experimental CP's is markedly smaller in\nAl than in Li. This indicates that, with increasing electron density, the\nconventional picture of the electron gas becomes more representative of the\nmomentum density and that shortcomings of the LDA framework in describing the\nelectron correlation effects become less important."
    },
    {
        "anchor": "Full-scale field-free spin-orbit switching of the CoPt layer grown on\n  vicinal substrates: A simple, reliable and field-free spin orbit torque (SOT)-induced\nmagnetization switching is a key ingredient for the development of the\nelectrical controllable spintronic devices. Recently, the SOT induced\ndeterministic switching of the CoPt single layer has attracts a lot of\ninterests, as it could simplifies the structure and add new flexibility in the\ndesign of SOT devices, compared with the Ferromagnet/Heavy metal bilayer\ncounterparts. Unfortunately, under the field-free switching strategies used\nnowadays, the switching of the CoPt layer is often partial, which sets a major\nobstacle for the practical applications. In this study, by growing the CoPt on\nvicinal substrates, we could achieve the full-scale (100% switching ratio)\nfield-free switching of the CoPt layer. We demonstrate that when grown on\nvicinal substrates, the magnetic easy axis of the CoPt could be tilted from the\nnormal direction of the film plane; the strength of Dzyaloshinskii Moriya\ninteraction (DMI) would be also be tuned as well. Micromagnetic simulation\nfurther reveal that the field-free switching stems from tilted magnetic\nanisotropy induced by the vicinal substrate, while the enhancement of DMI help\nreducing the critical switching current. In addition, we also found that the\nvicinal substrates could also enhance the SOT efficiency. With such simple\nstructure, full-scale switching, tunable DMI and SOT efficiency, our results\nprovide a new knob for the design SOT-MRAM and future spintronic devices.",
        "positive": "Rectification at Graphene-Semiconductor Interfaces: Zero-Gap\n  Semiconductor Based Diodes: Using current-voltage (I-V) and capacitance-voltage (C-V) measurements, we\nreport on the unusual physics and promising technical applications associated\nwith the formation of Schottky barriers at the interface of a one-atom-thick\nzero-gap semiconductor (graphene) and conventional semiconductors. When\nchemical vapor deposited graphene is transferred onto n-type Si, GaAs, 4H-SiC\nand GaN semiconductor substrates, there is a strong van der Waals attraction\nthat is accompanied by charge transfer across the interface and the formation\nof a rectifying (Schottky) barrier. Thermionic emission theory in conjunction\nwith the Schottky-Mott model within the context of bond-polarization theory\nprovides a surprisingly good description of the electrical properties.\nApplications, such as to sensors where in forward bias there is exponential\nsensitivity to changes in the Schottky barrier height due to the presence of\nabsorbates on the graphene or to analogue devices for which Schottky barriers\nare integral components are promising because of graphene's mechanical\nstability, its resistance to diffusion, its robustness at high temperatures and\nits demonstrated capability to embrace multiple functionalities."
    },
    {
        "anchor": "Experimentally Constrained Molecular Relaxation: The case of\n  hydrogenated amorphous silicon: We have extended our experimentally constrained molecular relaxation\ntechnique (P. Biswas {\\it et al}, Phys. Rev. B {\\bf 71} 54204 (2005)) to\nhydrogenated amorphous silicon: a 540-atom model with 7.4 % hydrogen and a\n611-atom model with 22 % hydrogen were constructed. Starting from a random\nconfiguration, using physically relevant constraints, {\\it ab initio}\ninteractions and the experimental static structure factor, we construct\nrealistic models of hydrogenated amorphous silicon. Our models confirm the\npresence of a high frequency localized band in the vibrational density of\nstates due to Si-H vibration that has been observed in a recent vibrational\ntransient grating measurements on plasma enhanced chemical vapor deposited\nfilms of hydrogenated amorphous silicon.",
        "positive": "Exchange interactions and temperature dependence of the magnetization in\n  half--metallic Heusler alloys: We study the exchange interactions in half-metallic Heusler alloys using\nfirst-principles calculations in conjunction with the frozen-magnon\napproximation. The Curie temperature is estimated within both mean-field (MF)\nand random-phase-approximation (RPA) approaches. For the half-Heusler alloys\nNiMnSb and CoMnSb the dominant interaction is between the nearest Mn atoms. In\nthis case the MF and RPA estimations differ strongly. The RPA approach provides\nbetter agreement with experiment. The exchange interactions are more complex in\nthe case of full-Heusler alloys Co$_2$MnSi and Co$_2$CrAl where the dominant\neffects are the inter-sublattice interactions between the Mn(Cr) and Co atoms\nand between Co atoms at different sublattices. For these compounds we find that\nboth MF and RPA give very close values of the Curie temperature slightly\nunderestimating experimental quantities. We study the influence of the lattice\ncompression on the magnetic properties. The temperature dependence of the\nmagnetization is calculated using the RPA method within both quantum mechanical\nand classical approaches."
    },
    {
        "anchor": "Crystal-field interaction and oxygen stoichiometry effects in\n  strontium-doped rare-earth cobaltates: Inelastic neutron scattering was employed to study the crystal-field\ninteraction in the strontium-doped rare-earth compounds R(x)Sr(1-x)CoO(3-z)\n(R=Pr, Nd, Ho, and Er). Particular emphasis is laid on the effect of oxygen\ndeficiencies which naturally occur in the synthesis of these compounds. The\nobserved energy spectra are found to be the result of a superposition of\ncrystal fields with different nearest-neighbor oxygen coordination at the R\nsites. The experimental data are interpreted in terms of crystal-field\nparameters which behave in a consistent manner through the rare-earth series,\nthereby allowing a reliable extrapolation for rare-earth ions not considered in\nthe present work.",
        "positive": "Crystalline structure and XMCD studies of Co40Fe40B20 grown on Bi2Te3,\n  BiTeI and Bi2Se3: Epitaxial films of Co40Fe40B20 (further - CoFeB) were grown on Bi2Te3(001)\nand Bi2Se3(001) substrates by laser molecular beam epitaxy (LMBE) technique at\n200-400C. Bcc-type crystalline structure of CoFeB with (111) plane parallel to\n(001) plane of Bi2Te3 was observed, in contrast to polycrystalline CoFeB film\nformed on Bi2Se3(001) at RT using high-temperature seeding layer. Therefore,\nstructurally ordered ferromagnetic thin films were obtained on the topological\ninsulator surface for the first time. Using high energy electron diffraction\n(RHEED) 3D reciprocal space mapping, epitaxial relations of main\ncrystallographic axes for the CoFeB/ Bi2Te3 heterostructure were revealed. MOKE\nand AFM measurements showed the isotropic azimuthal in-plane behavior of\nmagnetization vector in CoFeB/ Bi2Te3, in contrast to 2nd order magnetic\nanisotropy seen in CoFeB/Bi2Se3. XPS measurements showed more stable behavior\nof CoFeB grown on Bi2Te3 to the oxidation, in compare to CoFeB grown on Bi2Se3.\nXAS and XMCD measurements of both concerned nanostructures allowed calculation\nof spin and orbital magnetic moments for Co and Fe. Additionally, crystalline\nstructure and XMCD response of the CoFeB/BiTeI and Co55Fe45/BiTeI systems were\nstudied, epitaxial relations of main crystallographic axes were found, and spin\nand orbital magnetic moments were calculated."
    },
    {
        "anchor": "Tailoring Optical Excitation to Control Magnetic Skyrmion Nucleation: In ferromagnetic multilayers, a single laser pulse with a fluence above an\noptical nucleation threshold can create magnetic skyrmions, which are randomly\ndistributed over the area of the laser spot. However, in order to study the\ndynamics of skyrmions and for their application in future data technology, a\ncontrollable localization of the skyrmion nucleation sites is crucial. Here, it\nis demonstrated that patterned reflective masks behind a thin magnetic film can\nbe designed to locally tailor the optical excitation amplitudes reached,\nleading to spatially controlled skyrmion nucleation on the nanometer scale.\nUsing x-ray microscopy, the influence of nanopatterned back-side aluminum masks\non the optical excitation is studied in two sample geometries with varying\nlayer sequence of substrate and magnetic Co/Pt multilayer. Surprisingly, the\nmasks' effect on suppressing or enhancing skymion nucleation reverses when\nchanging this sequence. Moreover, optical near-field enhancements additionally\naffect the spatial arrangement of the nucleated skyrmions. Simulations of the\nspatial modulation of the laser excitation, and the following heat transfer\nacross the interfaces in the two sample geometries are employed to explain\nthese observations. The results demonstrate a reliable approach to add\nnanometer-scale spatial control to optically induced magnetization processes on\nultrafast timescales.",
        "positive": "Hidden spin-orbital texture at the $\\bar\u0393$-located valence band\n  maximum of a transition metal dichalcogenide semiconductor: Finding stimuli capable of driving an imbalance of spin-polarised electrons\nwithin a solid is the central challenge in the development of spintronic\ndevices. However, without the aid of magnetism, routes towards this goal are\nhighly constrained with only a few suitable pairings of compounds and driving\nmechanisms found to date. Here, through spin- and angle-resolved photoemission\nalong with density functional theory, we establish how the $p$-derived bulk\nvalence bands of semiconducting 1T-HfSe$_2$ possess a local, ground-state spin\ntexture spatially confined within each Se-sublayer due to strong\nsublayer-localised electric dipoles orientated along the $c$-axis. This hidden\nspin-polarisation manifests in a `coupled spin-orbital texture' with\nin-equivalent contributions from the constituent $p$-orbitals. While the\noverall spin-orbital texture for each Se sublayer is in strict adherence to\ntime-reversal symmetry (TRS), spin-orbital mixing terms with net polarisations\nat time-reversal invariant momenta are locally maintained. These apparent\nTRS-breaking contributions dominate, and can be selectively tuned between with\na choice of linear light polarisation, facilitating the observation of\npronounced spin-polarisations at the Brillouin zone centre for all $k_z$. We\ndiscuss the implications for the generation of spin-polarised populations from\n1T-structured transition metal dichalcogenides using a fixed energy, linearly\npolarised light source."
    },
    {
        "anchor": "Finite-size errors in continuum quantum Monte Carlo calculations: We analyze the problem of eliminating finite-size errors from quantum Monte\nCarlo (QMC) energy data. We demonstrate that both (i) adding a recently\nproposed [S. Chiesa et al., Phys. Rev. Lett. 97, 076404 (2006)] finite-size\ncorrection to the Ewald energy and (ii) using the model periodic Coulomb (MPC)\ninteraction [L. M. Fraser et al., Phys. Rev. B 53, 1814 (1996); P. R. C. Kent\net al., Phys. Rev. B 59, 1917 (1999); A. J. Williamson et al., Phys. Rev. B 55,\n4851 (1997)] are good solutions to the problem of removing finite-size effects\nfrom the interaction energy in cubic systems, provided the exchange-correlation\n(XC) hole has converged with respect to system size. However, we find that the\nMPC interaction distorts the XC hole in finite systems, implying that the Ewald\ninteraction should be used to generate the configuration distribution. The\nfinite-size correction of Chiesa et al. is shown to be incomplete in systems of\nlow symmetry. Beyond-leading-order corrections to the kinetic energy are found\nto be necessary at intermediate and high densities, and we investigate the\neffect of adding such corrections to QMC data for the homogeneous electron gas.\nWe analyze finite-size errors in two-dimensional systems and show that the\nleading-order behavior differs from that which has hitherto been supposed. We\ncompare the efficiency of different twist-averaging methods for reducing\nsingle-particle finite-size errors and we examine the performance of various\nfinite-size extrapolation formulas. Finally, we investigate the system-size\nscaling of biases in diffusion QMC.",
        "positive": "Exploring the interfacial coupling between graphene and the\n  antiferromagnetic insulator MnPSe$_3$: Interfacial coupling between graphene and other 2D materials can give rise to\nintriguing physical phenomena. In particular, several theoretical studies\npredict that the interplay between graphene and an antiferromagnetic insulator\ncould lead to the emergence of quantum anomalous Hall phases. However, such\nphases have not been observed experimentally yet, and further experimental\nstudies are needed to reveal the interaction between graphene and\nantiferromagnetic insulators. Here, we report the study in heterostructures\ncomposed of graphene and the antiferromagnetic insulator MnPSe$_3$. It is found\nthat the MnPSe$_3$ has little impact on the quantum Hall phases apart from\ndoping graphene via interfacial charge transfer. However, the magnetic order\ncan contribute indirectly via process like Kondo effect, as evidenced by the\nobserved minimum in the temperature-resistance curve between 20-40 K, far below\nthe N\\'eel temperature (70 K)."
    },
    {
        "anchor": "High pO2 Floating Zone Crystal Growth of the Perovskite Nickelate PrNiO3: Single crystals of PrNiO3 were grown under an oxygen pressure of 295 bar\nusing a unique high-pressure optical-image floating zone furnace. The crystals,\nwith volume in excess of 1 mm3, were characterized structurally using single\ncrystal and powder X-ray diffraction. Resistivity, specific heat, and magnetic\nsusceptibility were measured, all of which evidenced an abrupt, first order\nmetal-insulator transition (MIT) at ~130 K, in agreement with previous\nliterature reports on polycrystalline specimens. Temperature-dependent single\ncrystal diffraction was performed to investigate changes through the MIT. Our\nstudy demonstrates the opportunity space for high fugacity, reactive\nenvironments for single crystal growth specifically of perovskite nickelates\nbut more generally to correlated electron oxides.",
        "positive": "Designed spin-texture-lattice to control anisotropic magnon transport in\n  antiferromagnets: Spin waves in magnetic materials are promising information carriers for\nfuture computing technologies due to their ultra-low energy dissipation and\nlong coherence length. Antiferromagnets are strong candidate materials due, in\npart, to their stability to external fields and larger group velocities.\nMultiferroic aniferromagnets, such as BiFeO$_3$ (BFO), have an additional\ndegree of freedom stemming from magnetoelectric coupling, allowing for control\nof the magnetic structure, and thus spin waves, with electric field.\nUnfortunately, spin-wave propagation in BFO is not well understood due to the\ncomplexity of the magnetic structure. In this work, we explore long-range spin\ntransport within an epitaxially engineered, electrically tunable,\none-dimensional (1D) magnonic crystal. We discover a striking anisotropy in the\nspin transport parallel and perpendicular to the 1D crystal axis. Multiscale\ntheory and simulation suggests that this preferential magnon conduction emerges\nfrom a combination of a population imbalance in its dispersion, as well as\nanisotropic structural scattering. This work provides a pathway to\nelectrically-reconfigurable magnonic crystals in antiferromagnets."
    },
    {
        "anchor": "Additional Boundary Condition for the Wire Medium: In this paper, it is proved that the continuity of the tangential components\nof the average electric and magnetic fields is insufficient to describe the\nreflection of plane waves by a set of thin parallel wires embedded in a\ndielectric host using a homogenization approach. It is shown that an additional\nboundary condition is required to conveniently model a slab of the homogenized\nmetamaterial. In order to understand how the different electromagnetic modes\nare excited at the interface, the problem of reflection of a plane wave by a\nset of semi-infinite parallel wires is solved analytically within the thin-wire\napproximation. Based on the derived result and other arguments, a new boundary\ncondition is proposed for the homogenized wire medium. Extensive numerical\nsimulations support our theoretical analysis, and show that when the additional\nboundary condition is considered the agreement between full wave results and\nhomogenization theory is very good even for wavelengths comparable with the\nlattice constant.",
        "positive": "Synthesis of Large-Area MoS2 Atomic Layers with Chemical Vapor\n  Deposition: Large-area MoS2 atomic layers are synthesized on SiO2 substrates by chemical\nvapor deposition using MoO3 and S powders as the reactants. Optical,\nmicroscopic and electrical measurements suggest that the synthetic process\nleads to the growth of MoS2 monolayer. The TEM images verify that the\nsynthesized MoS2 sheets are highly crystalline."
    },
    {
        "anchor": "Magneto-optical study of ZnO based diluted magnetic semiconductors: Magneto-optical properties of ZnO:Co and ZnO:Ni films were measured.\nMagnetization measurements show that some of the films are paramagnetic and\nothers are ferromagnetic. Magnetic circular dichroism clarified that Zn1-xCoxO\nand Zn1-xNixO included in samples are paramagnetic diluted magnetic\nsemiconductors. Ferromagnetic precipitations seem to be responsible for the\nobserved ferromagnetic behaviors. Criteria to judge the ferromagnetic DMS are\nalso discussed.",
        "positive": "Growth and reductive transformation of a gold shell around pyramidal\n  cadmium selenide nanocrystals: We report the growth of an unstable shell-like gold structure around\ndihexagonal pyramidal CdSe nanocrystals in organic solution and the structural\ntransformation to spherical domains by two means: i) electron beam irradiation\n(in situ) and (ii) addition of a strong reducing agent during synthesis. By\nvarying the conditions of gold deposition, such as ligands present or the\ngeometry of the CdSe nanocrystals, we were able to tune the gold domain size\nbetween 1.4 nm to 3.9 nm and gain important information on the role of surface\nchemistry in hetero nanoparticle synthesis and seed reactivity, both of which\nare crucial points regarding the chemical design of new materials for\nphotocatalysis and optoelectronic applications."
    },
    {
        "anchor": "Thermodynamic restrictions on linear reversible and irreversible\n  thermo-electro-magneto-mechanical processes: A unified thermodynamic framework for characterization of functional\nmaterials is developed. This framework encompasses linear reversible and\nirreversible processes with thermal, electrical, magnetic, and/or mechanical\neffects coupled. The comprehensive framework combines the principles of\nclassical equilibrium and non-equilibrium thermodynamics with electrodynamics\nof continua in the infinitesimal strain regime.\n  In the first part of this paper, linear Thermo-Electro-Magneto-Mechanical\n(TEMM) quasistatic processes are characterized. Thermodynamic stability\nconditions are further imposed on the linear constitutive model and\nrestrictions on the corresponding material constants are derived. The framework\nis then extended to irreversible transport phenomena including thermoelectric,\nthermomagnetic and the state-of-the-art spintronic and spin caloritronic\neffects. Using Onsager's reciprocity relationships and the dissipation\ninequality, restrictions on the kinetic coefficients corresponding to charge,\nheat and spin transport processes are derived. All the constitutive models are\naccompanied by multiphysics interaction diagrams that highlight the various\nprocesses that can be characterized using this framework.",
        "positive": "Spin Fluctuations Yield zT Enhancement in Ferromagnets: Thermal fluctuation of local magnetization in magnetic metals intercoupled\nwith charge carriers and phonons offers a path to enhance thermoelectric\nperformance. The thermopower enhancement by spin fluctuations (SF) has been\nobserved before. However, the crucial evidence for enhancing\nthermoelectric-figure-of-merit (zT) by SF has not been reported until now. Here\nwe report evidence for such enhancement in the ferromagnetic CrTe. The SF leads\nto nearly 80% zT enhancement in ferromagnetic CrTe near and below TC~335 K. The\nferromagnetism in CrTe is originated from the collective electronic and\nlocalized magnetic moments. The field-dependent transport properties\ndemonstrate the profound impact of SF on the electrons and phonons. The SF\nsimultaneously enhances the thermopower and reduces the thermal conductivity.\nUnder an external magnetic field, the enhancement in thermopower is suppressed,\nand the thermal conductivity is enhanced, evidencing the existence of a strong\nSF near and below TC. The anomalous thermoelectric transport properties are\nanalyzed based on theoretical models, and a good agreement with experimental\ndata is found. Furthermore, the detailed analysis proves an insignificant\nimpact from spin-wave contribution to the transport properties. This study\ncontributes to the fundamental understanding of spin fluctuation for designing\nhigh-performance spin-driven thermoelectric materials."
    },
    {
        "anchor": "Uncertainty Quantification of DFT-predicted Finite Temperature\n  Thermodynamic Properties within the Debye Model: Finite-temperature effects can be included by calculating the vibrations\nproperties and this can greatly improve the fidelity of computational\nscreening. An important challenge for DFT-based screening is the sensitivity of\nthe predictions to the choice of the exchange correlation function. In this\nwork, we rigorously explore the sensitivity of finite temperature thermodynamic\nproperties to the choice of the exchange correlation functional using the\nbuilt-in error estimation capabilities within the Bayesian Error Estimation\nFunctional. The vibrational properties are estimated using the Debye model and\nwe quantify the uncertainty associated with finite-temperature properties for a\ndiverse collection of materials. We find good agreement with experiment and\nsmall spread in predictions over different exchange correlation functionals for\nMg, Al$_2$O$_3$, Al, Ca, and GaAs. In the case of Li, Li$_2$O, and NiO,\nhowever, we find a large spread in predictions as well as disagreement between\nexperiment and functionals due to complex bonding environments. While the\nenergetics generated by BEEF-vdW ensemble is typically normal, the complex\nmapping through the Debye model leads to the derived finite temperature\nproperties having non-Gaussian behavior. We test a wide variety of probability\ndistributions that best represent the finite temperature distribution and find\nthat properties such as specific heat, Gibbs free energy, entropy, and the\nthermal expansion coefficient are well described by normal or transformed\nnormal distributions, while the prediction spread of volume at a given\ntemperature does not appear to be drawn from a single distribution.",
        "positive": "Quantum-well resonances caused by partial confinement in MgO-based\n  magnetic tunnel junctions: Quantum-well resonance is achieved through partial confinement in magnetic\ntunnel junctions (MTJs), which provides a more concise core structure and\nadditional degree of freedom to regulate quantum-well levels. Using\nAl/Fe/MgO/Fe/Al and Fe/Al/Fe/MgO/Fe/Al/Fe MTJs as examples, via\nfirst-principles calculations, we demonstrate that the partial confinement of\n{\\Delta}1 electron at Al/Fe interface and the full confinement at Fe/MgO\ninterface combine to produce quantum-well resonances in Fe. The quantum-well\nlevels of Fe can be periodically adjusted by two degrees of freedom: Fe and Al\nthickness. The oscillation period obtained from conductance is 2.13 ML Fe (8 ML\nAl), in agreement with 2.25 ML Fe (8.33 ML Al) calculated by bcc-Fe (fcc-Al)\nband. The combination of long and short periods enables quantum-well levels to\nbe finely adjusted, yielding an ultrahigh optimistic TMR effect of 160000 %.\nOur results open the way for the design and application of quantum-well\nresonances in spintronics devices."
    },
    {
        "anchor": "Direct observation of Oersted-field-induced magnetization dynamics in\n  magnetic nanostripes: We have used time-resolved x-ray photoemission electron microscopy to\ninvestigate the magnetization dynamics induced by nanosecond current pulses in\nNiFe/Cu/Co nanostripes. A large tilt of the NiFe magnetization in the direction\ntransverse to the stripe is observed during the pulses. We show that this\neffect cannot be quantitatively understood from the amplitude of the Oersted\nfield and the shape anisotropy. High frequency oscillations observed at the\nonset of the pulses are attributed to precessional motion of the NiFe\nmagnetization about the effective field. We discuss the possible origins of the\nlarge magnetization tilt and the potential implications of the static and\ndynamic effects of the Oersted field on current-induced domain wall motion in\nsuch stripes.",
        "positive": "Ionic liquids under confinement: From systematic variations of the ion\n  and pore sizes towards an understanding of structure and dynamics in complex\n  porous carbons: We use molecular simulations of an ionic liquid in contact with a range of\nnanoporous carbons to investigate correlations between ion size, pore size,\npore topology and properties of the adsorbed ions. We show that diffusion\ncoefficients increase with the anion size and, surprisingly, with the quantity\nof adsorbed ions. Both findings are interpreted in terms of confinement: when\nthe in-pore population increases additional ions are located in less confined\nsites and diffuse faster. Simulations in which the pores are enlarged while\nkeeping the topology constant comfort these observations. The interpretation of\nproperties across structures is more challenging. An interesting point is that\nsmaller pores do not necessarily lead to larger confinement. In this work, the\nhighest degrees of confinements are observed for intermediate pore sizes. We\nalso show a correlation between the quantity of adsorbed ions and the ratio\nbetween the maximum pore diameter and the pore limiting diameter."
    },
    {
        "anchor": "Ni- and Co-struvites: Revealing crystallization mechanisms and crystal\n  engineering towards applicational use of transition metal phosphates: Industrial and agricultural waste streams, which contain high concentrations\nof NH4+, PO43- and transition metals are environmentally harmful and toxic\npollutants. At the same time phosphorous and transition metals constitute\nhighly valuable resources. Typically, separate pathways have been considered to\nextract hazardous transition metals or phosphate, independently from each\nother. Investigations on the simultaneous removal of multiple components have\nbeen studied only to a limited extent. Here, we report the synthesis routes for\nCo- and Ni-struvites (NH4MPO4.6H2O, M = Ni2+, Co2+ ), which allow for P,\nammonia and metal co precipitation. By evaluating different reaction\nparameters, the phase and stability of transition metal struvites, as well as\ntheir crystal morphologies, and sizes could be optimized. Ni-struvite is stable\nin a wide reactant concentration range and at different metal/phosphorus (M/P)\nratios, whereas Co-struvite only forms at low M/P ratios. Detailed\ninvestigations of the precipitation process using ex situ and in situ\ntechniques provided insights into the crystallization mechanisms/crystal\nengineering of these materials. M-struvites crystallize via intermediate\ncolloidal nanophases, which subsequently aggregate and condense to final\ncrystals after extended reaction times. However, the exact reaction kinetics of\nthe formation of a final crystalline product varies significantly depending on\nthe metal cation involved in the precipitation process: several seconds (Mg) to\nminutes (Ni) to hours (Co). The achieved level of control over the morphology\nand size, makes precipitation of metal struvites a promising method for direct\nmetal recovery and binding them in the form of valuable phosphate raw\nmaterials. Under this paradigm, the crystals can be potentially upcycled as\nprecursor powders for electrochemical applications, which require transition\nmetal phosphates (TMPs).",
        "positive": "Theory of harmonic dissipation in disordered solids: Mechanical spectroscopy, i.e. cyclic deformations at varying frequencies, is\nused theoretically and numerically to measure dissipation in model glasses.\nFrom a normal mode analysis, we show that in the high-frequency THz regime\nwhere dissipation is harmonic, the quality factor (or loss angle) can be\nexpressed analytically. This expression is validated through non-equilibrium\nmolecular dynamics simulations applied to a model of amorphous silica\n(SiO$_2$). Dissipation is shown to arise from non-affine relaxations triggered\nby the applied strain through the excitation of vibrational eigenmodes that act\nas damped harmonic oscillators. We discuss an asymmetry vector field, which\nencodes the information about the structural origin of dissipation measured by\nmechanical spectroscopy. In the particular case of silica, we find that the\nmotion of oxygen atoms, which induce a deformation of Si-O-Si bonds is the main\ncontributor to harmonic energy dissipation."
    },
    {
        "anchor": "All-oxide spin Seebeck effects: We report the observation of longitudinal spin Seebeck effects (LSSE) in an\nall-oxide bilayer system comprising an IrO$_2$ film and an Y$_3$Fe$_5$O$_{12}$\nfilm. Spin currents generated by a temperature gradient across the\nIrO$_2$/Y$_3$Fe$_5$O$_{12}$ interface were detected as electric voltage via the\ninverse spin Hall effect in the conductive IrO$_2$ layer. This electric voltage\nis proportional to the magnitude of the temperature gradient and its magnetic\nfield dependence is well consistent with the characteristic of the LSSE. This\ndemonstration may lead to the realization of low-cost, stable, and transparent\nspin-current-driven thermoelectric devices.",
        "positive": "Spin current generation from an epitaxial tungsten dioxide WO$_{2}$: We report on efficient spin current generation at room temperature in rutile\ntype WO$_{2}$ grown on Al$_{2}$O$_{3}$(0001) substrate. The optimal WO$_{2}$\nfilm has (010)-oriented monoclinically distorted rutile structure with metallic\nconductivity due to 5$\\it{d}$$^2$ electrons, as characterized by x-ray\ndiffraction, electronic transport, and x-ray photoelectron spectroscopy. By\nconducting harmonic Hall measurement in Ni$_{81}$Fe$_{19}$/WO$_{2}$ bilayer, we\nestimate two symmetries of the spin-orbit torque (SOT), i.e., dampinglike (DL)\nand fieldlike ones to find that the former is larger than the latter. By\ncomparison with the Ni$_{81}$Fe$_{19}$/W control sample, the observed DL SOT\nefficiency $\\xi$$_{DL}$ of WO$_{2}$ (+0.174) is about two thirds of that of W\n(-0.281) in magnitude, with a striking difference in their signs. The magnitude\nof the $\\xi$$_{DL}$ of WO$_{2}$ exhibits comparable value to those of widely\nreported Pt and Ta, and Ir oxide IrO$_{2}$. The positive sign of the\n$\\xi$$_{DL}$ of WO$_{2}$ can be explained by the preceding theoretical study\nbased on the 4$\\it{d}$ oxides. These results highlight that the epitaxial\nWO$_{2}$ offers a great opportunity of rutile oxides with spintronic\nfunctionalities, leading to future spin-orbit torque-controlled devices."
    },
    {
        "anchor": "Chirality selective magnon-phonon hybridization and magnon-induced\n  chiral phonons in a layered zigzag antiferromagnet: Two-dimensional (2D) magnetic systems possess versatile magnetic order and\ncan host tunable magnons carrying spin angular momenta. Recent advances show\nangular momentum can also be carried by lattice vibrations in the form of\nchiral phonons. However, the interplay between magnons and chiral phonons as\nwell as the details of chiral phonon formation in a magnetic system are yet to\nbe explored. Here, we report the observation of magnon-induced chiral phonons\nand chirality selective magnon-phonon hybridization in a layered zigzag\nantiferromagnet (AFM) FePSe$_3$. With a combination of magneto-infrared and\nmagneto-Raman spectroscopy, we observe chiral magnon polarons (chiMP), the new\nhybridized quasiparticles, at zero magnetic field. The hybridization gap\nreaches 0.25~meV and survives down to the quadrilayer limit. Via first\nprinciple calculations, we uncover a coherent coupling between AFM magnons and\nchiral phonons with parallel angular momenta, which arises from the underlying\nphonon and space group symmetries. This coupling lifts the chiral phonon\ndegeneracy and gives rise to an unusual Raman circular polarization of the\nchiMP branches. The observation of coherent chiral spin-lattice excitations at\nzero magnetic field paves the way for angular momentum-based hybrid phononic\nand magnonic devices.",
        "positive": "Reflection-enhanced gain in traveling-wave parametric amplifiers: The operating principle of traveling-wave parametric amplifiers is typically\nunderstood in terms of the standard coupled mode theory, which describes the\nevolution of forward propagating waves without any reflections, i.e. for\nperfect impedance matching. However, in practice, superconducting microwave\namplifiers are unmatched nonlinear finite-length devices, where the reflecting\nwaves undergo complex parametric processes, not described by the standard\ncoupled mode theory. Here, we present an analytical solution for the TWPA gain,\nwhich includes the interaction of reflected waves. These reflections result in\ncorrections to the well-known results of the standard coupled mode theory,\nwhich are obtained for both 3-wave and 4-wave mixing processes. Due to these\nreflections, gain is enhanced and unwanted nonlinear phase modulations are\nsuppressed. Predictions of the model are experimentally demonstrated on two\ntypes of unmatched TWPA, based on coplanar waveguides with a central wire\nconsisting of i) a high kinetic inductance superconductor, and ii) an array of\n2000 Josephson junctions."
    },
    {
        "anchor": "Magnetization Process of the Spin-S Kagome-Lattice Heisenberg\n  Antiferromagnet: The magnetization process of the spin-S Heisenberg antiferromagnet on the\nkagome lattice is studied by the numerical-diagonalization method. Our\nnumerical-diagonalization data for small finite-size clusters with S=1, 3/2, 2,\nand 5/2 suggest that a magnetization plateau appears at one-third of the height\nof the saturation in the magnetization process irrespective of S. We discuss\nthe S dependences of the edge fields and the width of the plateau in comparison\nwith recent results obtained by real-space perturbation theory.",
        "positive": "Investigation of quantum-dimensional structure parameters by X-ray\n  optical, scanning tunneling and transmission electron microscopy: Application of the two-wavelength X-ray reflectometry to exploration of\nGe/Si(001) hereostructures with dense chains of stacked Ge quantum dots is\npresented"
    },
    {
        "anchor": "Analysis of the Transport Process Providing Spin Injection through an\n  Fe/AlGaAs Schottky Barrier: Electron spin polarizations of 32% are obtained in a GaAs quantum well via\nelectrical injection through a reverse-biased Fe/AlGaAs Schottky contact. An\nanalysis of the transport data using the Rowell criteria demonstrates that\nsingle step tunneling is the dominant transport mechanism. The current-voltage\ndata show a clear zero-bias anomaly and phonon signatures corresponding to the\nGaAs-like and AlAs-like longitudinal-optical phonon modes of the AlGaAs\nbarrier, providing further evidence for tunneling. These results provide\nexperimental confirmation of several theoretical analyses indicating that\ntunneling enables significant spin injection from a metal into a semiconductor.",
        "positive": "Metallic atomic wires on a patterned dihydrogeneted Si(001): Electronic structure calculations for atomic wire of metals like Al, Ga and\nIn are performed for a patterned dihydrogeneted Si(001):1 $\\times$ 1 in search\nof structures with metallic behavior. The dihydrogeneted Si(001) is patterned\nby depassivating hygrozen atoms only from one row of Si atoms along the\n[1$\\bar{1}$0] direction. Various structures of adsorbed metals and their\nelectronic properties are examined. It is found that Al and Ga atomic wire\nstructures with metallic property are strongly unstable towards the formation\nof buckled metal dimers leading to semiconducting behavior. Indium atomic wire,\nhowever, displays only marginal preference towards the formation of symmetric\ndimers staying close to the metallic limit. The reasons behind the lack of\nmetallic atomic wires are explored. In addition, a direction is proposed for\nthe realization of metallic wires on the dihydrogeneted Si(001)."
    },
    {
        "anchor": "On the Hill and Kolmogorov statistics and the K-function representation\n  of judiciously modified Avrami kinetics: This study concerns the phase transformation kinetics and pertains to the\nprocesses of crystallisation of amorphous polymers, ceramics, and bulk metallic\nglasses (BMG), as well as solid state transformations by the nucleation and\ngrowth mechanism. It is also likely to be relevant to the description of\ndissolution and precipitation processes, and more generally chemical reaction\nkinetics, as well as biochemical processes such as ligand binding, haemoglobin\noxygenation, etc. The mathematical framework is examined of the of the 'knee'\nfunction, or K-function, and its implications are explored.",
        "positive": "Atomistic Graph Neural Networks for metals: Application to bcc iron: The prediction of the atomistic structure and properties of crystals\nincluding defects based on ab-initio accurate simulations is essential for\nunraveling the nano-scale mechanisms that control the micromechanical and\nmacroscopic behaviour of metals. Density functional theory (DFT) can enable the\nquantum-accurate prediction of some of these properties, however at high\ncomputational costs and thus limited to systems of ~1,000 atoms. In order to\npredict with quantum-accuracy the mechanical behaviour of nanoscale structures\ninvolving from thousands to several millions of atoms, machine learning\ninteratomic potentials have been recently developed. Here, we explore the\nperformance of a new class of interatomic potentials based on Graph Neural\nNetworks (GNNs), a recent field of research in Deep Learning. Two\nstate-of-the-art GNN models are considered, SchNet and DimeNet, and trained on\nan extensive DFT database of ferromagnetic bcc iron. We find that the DimeNet\nGNN Fe potential including three-body terms can reproduce with DFT accuracy the\nequation of state and the Bain path, as well as defected configurations\n(vacancy and surfaces). To the best of our knowledge, this is the first\ndemonstration of the capability of GNN of reproducing the energetics of defects\nin bcc iron. We provide an open-source implementation of DimeNet that can be\nused to train other metallic systems for further exploration of the GNN\ncapabilities."
    },
    {
        "anchor": "Plastic deformation of the CaMg$_{2}$ C14-Laves phase from\n  50-250$^\\circ$C: Intermetallic phases can significantly improve the creep resistance of\nmagnesium alloys, extending their use to higher temperatures. However, little\nis known about the deformation behaviour of these phases at application\ntemperatures, which are commonly below their macroscopic\nbrittle-to-ductile-transition temperature. In this study, we therefore\ninvestigate the activation of different slip systems of the CaMg$_2$ phase and\nthe occurrence of serrated yielding in the temperature range from 50$^\\circ$C\nto 250$^\\circ$C. A decreasing amount of serrated flow with increasing\ntemperature suggests that solute atoms govern the flow behaviour when the\nCaMg$_{2}$ phase is off-stoichiometric.",
        "positive": "Evolution of coherent islands during strained-layer Volmer-Weber growth\n  of Si on Ge(111): This paper withdrawn by the authors due to errors in the TEM measurements of\nthe densities and sizes of small islands."
    },
    {
        "anchor": "Resolving the Nucleation Stage in Atomic Layer Deposition of Hafnium\n  Oxide on Graphene: The integration of two-dimensional (2D) materials with functional non-2D\nmaterials such as metal oxides is of key importance for many applications, but\nunderlying mechanisms for such non-2D/2D interfacing remain largely elusive at\nthe atomic scale. To address this, we here investigate the nucleation stage in\natomic layer deposition (ALD) of the important metal oxide HfO2 on chemical\nvapor deposited graphene using atomically resolved and element specific\nscanning transmission electron microscopy (STEM). To avoid any deleterious\ninfluence of polymer residues from pre-ALD graphene transfers we employ a\nsubstrate-assisted ALD process directly on the as grown graphene still\nremaining on its Cu growth catalyst support. Thereby we resolve at the atomic\nscale key factors governing the integration of non-2D metal oxides with 2D\nmaterials by ALD: Particular to our substrate-assisted ALD process we find a\ngraphene-layer-dependent catalytic participation of the supporting Cu catalyst\nin the ALD process. We further confirm at high resolution the role of surface\nirregularities such as steps between graphene layers on oxide nucleation.\nEmploying the energy transfer from the scanning electron beam to in situ\ncrystallize the initially amorphous ALD HfO2 on graphene, we observe HfO2\ncrystallization to non-equilibrium HfO2 polymorphs (cubic/tetragonal). Finally\nour data indicates a critical role of the graphene's atmospheric adventitious\ncarbon contamination on the ALD process whereby this contamination acts as an\nunintentional seeding layer for metal oxide ALD nucleation on graphene under\nour conditions. As atmospheric adventitious carbon contamination is hard to\navoid in any scalable 2D materials processing, this is a critical factor in ALD\nrecipe development for 2D materials coating. Combined our work highlights\nseveral key mechanisms underlying scalable ALD oxide growth on 2D materials.",
        "positive": "Towards quantifying the role of exact exchange in predictions of\n  transition metal complex properties: We estimate the prediction sensitivity with respect to Hartree-Fock exchange\nin approximate density functionals for representative Fe(II) and Fe(III)\noctahedral complexes. Based on the observation that the range of parameters\nspanned by the most widely-employed functionals is relatively narrow, we\ncompute electronic structure property and spin-state orderings across a\nrelatively broad range of Hartree-Fock exchange (0-50%) ratios. For the entire\nrange considered, we consistently observe linear relationships between\nspin-state ordering that differ only based on the element of the direct ligand\nand thus may be broadly employed as measures of functional sensitivity in\npredictions of organometallic compounds. The role Hartree-Fock exchange in\nhybrid functionals is often assumed to play is to correct self-interaction\nerror-driven electron delocalization (e.g. from transition metal centers to\nneighboring ligands). Surprisingly, we instead observe that increasing\nHartree-Fock exchange reduces charge on iron centers, corresponding to\neffective delocalization of charge to ligands, thus challenging notions of the\nrole of Hartree-Fock exchange in shifting predictions of spin-state ordering."
    },
    {
        "anchor": "Relaxation mechanism of GaP grown on 001 Sisubstrates: influence of\n  defects on the growth of AlGaPlayers on GaP/Si templates: The mechanical stability of commercial GaP/Si templates during thermal\nan-nealing and subsequent MOCVD growth of GaP and AlGaP is\ninvestigated.Although the GaP layer of the template originally presents an\nexcellent surfacemorphology, annealing at high enough temperatures to remove\nthe native oxideprior to growth leads to plastic relaxation, accompanied by a\nvariety of defects,including a dense grid of micro-twins. These micro-twins\ndetrimentally affectGaP and AlGaP layers grown subsequently on the template.",
        "positive": "Si Substitution in Nanotubes and Graphene via Intermittent Vacancies: The properties of single-walled carbon nanotubes (SWCNTs) and graphene can be\nmodified by the presence of covalently bound impurities. Although this can be\nachieved by introducing chemical additives during synthesis, that often hinders\ngrowth and leads to limited crystallite size and quality. Here, through the\nsimultaneous formation of vacancies with low-energy argon plasma and the\nthermal activation of adatom diffusion by laser irradiation, silicon impurities\nare incorporated into the lattice of both materials. After an exposure of\n$\\sim$1 ion/nm$^{2}$, we find Si substitution densities of 0.15 nm$^{-2}$ in\ngraphene and 0.05 nm$^{-2}$ in nanotubes, as revealed by atomically resolved\nscanning transmission electron microscopy. In good agreement with predictions\nof Ar irradiation effects in SWCNTs, we find Si incorporated in both mono- and\ndivacancies, with $\\sim$2/3 being of the first type. Controlled inclusion of\nimpurities in the quasi-1D and 2D carbon lattices may prove useful for\napplications such as gas sensing, and a similar approach might also be used to\nsubstitute other elements with migration barriers lower than that of carbon."
    },
    {
        "anchor": "Enhanced Ferromagnetism of CrI3 Bilayer by Self-Intercalation: Two-dimensional (2D) ferromagnets with high Curie temperature have long been\nthe pursuit for electronic and spintronic applications. CrI3 is a rising star\nof intrinsic 2D ferromagnets, however, it suffers from weak exchange coupling.\nHere we propose a general strategy of self-intercalation to achieve enhanced\nferromagnetism in bilayer CrI3. We showed that filling either Cr or I atoms\ninto the van der Waals gap of stacked and twisted CrI3 bilayers can induce the\ndouble exchange effect and significantly strengthen the interlayer\nferromagnetic coupling. According to our first-principles calculations, the\nintercalated native atoms act as covalent bridge between two CrI3 layers and\nlead to discrepant oxidation states for the Cr atoms. These theoretical results\noffer a facile route to achieve high-Curie-temperature 2D magnets for device\nimplementation.",
        "positive": "The effects of point defect type, location, and density on the Schottky\n  barrier height of Au/MoS2 hetero-junction: A first-principles study: Using DFT calculations, we investigate the effects of the type, location, and\ndensity of point defects in monolayer MoS2 on electronic structures and\nSchottky barrier heights (SBH) of Au/MoS2 heterojunction. Three types of point\ndefects in monolayer MoS2, that is, S monovacancy, S divacancy and MoS (Mo\nsubstitution at S site) antisite defects, are considered. The following\nfindings are revealed: (1) The SBH for the monolayer MoS2 with defects is\nuniversally higher than that for its defect-free counterpart. (2) S divacancy\nand MoS antisite defects increase the SBH to a larger extent than S\nmonovacancy. (3) A defect located in the inner sublayer of MoS2, which is\nadjacent to Au substrate, increases the SBH to a larger extent than that in the\nouter sublayer of MoS2. (4) An increase in defect density increases the SBH.\nThese findings indicate a large variation of SBH with the defect type,\nlocation, and concentration. We also compare our results with previously\nexperimentally measured SBH for Au/MoS2 contact and postulate possible reasons\nfor the large differences among existing experimental measurements and between\nexperimental measurements and theoretical predictions. The findings and\ninsights revealed here may provide practice guidelines for modulation and\noptimization of SBH in Au/MoS2 and similar heterojunctions via defect\nengineering."
    },
    {
        "anchor": "Mobility in semiconducting carbon nanotubes at finite carrier density: Carbon nanotube field-effect transistors operate over a wide range of\nelectron or hole density, controlled by the gate voltage. Here we calculate the\nmobility in semiconducting nanotubes as a function of carrier density and\nelectric field, for different tube diameters and temperature. The low-field\nmobility is a non-monotonic function of carrier density, and varies by as much\nas a factor of 4 at room temperature. At low density, with increasing field the\ndrift velocity reaches a maximum and then exhibits negative differential\nmobility, due to the non-parabolicity of the bandstructure. At a critical\ndensity $\\rho_c\\sim$ 0.35-0.5 electrons/nm, the drift velocity saturates at\naround one third of the Fermi velocity. Above $\\rho_c$, the velocity increases\nwith field strength with no apparent saturation.",
        "positive": "Comparative study of phase transitions in polycrystalline and epitaxial\n  BaTiO3 thin films by means of specific heat measurements: The experimental data on the thermal properties of the nanostructured\nperovskite ferroelectrics are presented and analysed. The ability of the\nmodified 3w method for specific heat measurements is discussed and illustrated\nby the thermal properties of the thin polycrystalline (BaTiO3 on fused SiO2,\n50-1100 nm) and epitaxial (BaTiO3 on MgO, 50-500 nm) films. The similarity of\nspecific heat, phase transition excess entropy evolution in polycrystalline\nfilms and nanograined ceramics is revealed. The data on the specific heat of\nepitaxial films show the extremely diffused anomaly near 400 K, the phase\ntransition has the weak tendency of shifting to higher temperatures with the\ndecreasing of the film thickness. No anomalies were detected for the thinnest\n(50 nm) film up to 480 K."
    },
    {
        "anchor": "Role of ambient air on photoluminescence and electrical conductivity of\n  assembly of ZnO Nanoparticles: Effect of ambient gases on photoluminescence (PL) and electrical conductivity\nof films prepared using ZnO nanoparticles (NPs) have been investigated. It is\nobserved that NPs of size below 20 nm kept inside a chamber exhibit complete\nreduction in their visible PL when oxygen partial pressure of the surrounding\ngases is decreased by evacuation. However the visible PL from ZnO NPs is\ninsensitive to other major gases present in the ambient air. The rate of change\nof PL intensity with pressure is inversely proportional to the ambient air\npressure and increases when particle size decreases due to the enhanced surface\nto volume ratio. On the other hand an assembly of ZnO NPs behaves as a complete\ninsulator in the presence of dry air and its major components like N2, O2 and\nCO2. Electrical conduction having resistivity ~102 - 103 {\\Omega}m is observed\nin the presence of humid air. The depletion layer formed at the NP surface\nafter acquiring donor electrons of ZnO by the adsorbed oxygen, has been found\nto control the visible PL and increases the contact potential barrier between\nthe NPs which in turn enhances the resistance of the film.",
        "positive": "Electronic structure and magnetic properties of Mn, Co, and\n  Ni-substitution of Fe in Fe4N: The magnetic properties of Mn, Co and Ni substituted Fe4N are calculated from\nfirst principles theory. It is found that the generalized gradient\napproximation reproduces with good accuracy the magnetic moment and equilibrium\nvolume for the parent Fe4N structure, with the atomic moment largest for the Fe\natom furthest away from the N atom (Fe I site), approaching a value of 3\nmuB/atom, whereas the Fe atom closer to the N atom (Fe II site) has a moment\ncloser to that of bcc Fe. Substitution of Fe for Mn, Co or Ni, shows an\nintricate behavior in which the Mn substitution clearly favors the Fe II site,\nNi favors substitution on the Fe I site and Co shows no strong preference for\neither lattice site. Ni and Co substitution results in a ferromagnetic coupling\nto the Fe atoms, whereas Mn couples antiferromagnetically on the Fe II site and\nferromagnetically on the Fe I site. For all types of doping, the total magnetic\nmoment is enhanced compared with Fe4N only in the energetically very\nunfavorable case of Mn doping at the Fe I site."
    },
    {
        "anchor": "Electric-Dipole Effect of Defects on Energy Band Alignment of Rutile and\n  Anatase TiO2: Titanium dioxide materials have been studied intensively and extensively due\nto photocatalytic applications. A long-standing open question is the energy\nband alignment of rutile and anatase TiO2 phases, which can affect the\nphotocatalytic process in the composite system. There are basically two\ncontradictory viewpoints about the alignment of these two TiO2 phases supported\nby respective experiments: 1) straddling type and 2) staggered type. In this\nwork, our DFT plus U calculations find that the perfect rutile (110) and\nanatase (101) surfaces have the straddling type band alignment, whereas the\nsurfaces with defects can turn the band alignment into the staggered type. The\nelectric dipoles induced by defects are responsible for the reversal of band\nalignment. Thus the defects introduced during preparations and post-treatment\nprocesses of materials are probably the answer to above open question regarding\nthe band alignment, which can be considered in real practice to tune the\nphotocatalytic activity of materials.",
        "positive": "Breaking the doping limit in silicon by deep impurities: N-type doping in Si by shallow impurities, such as P, As and Sb, exhibits an\nintrinsic limit due to the Fermi-level pinning via defect complexes at high\ndoping concentrations. Here we demonstrate that doping Si with the chalcogen Te\nby non-equilibrium processing, a deep double donor, can exceed this limit and\nyield higher electron concentrations. In contrast to shallow impurities, both\nthe interstitial Te fraction decreases with increasing doping concentration and\nsubstitutional Te dimers become the dominant configuration as effective donors,\nleading to a non-saturating carrier concentration as well as to an\ninsulator-to-metal transition. First-principle calculations reveal that the Te\ndimers possess the lowest formation energy and donate two electrons per dimer\nto the conduction band. These results provide novel insight into physics of\ndeep impurities and lead to a possible solution for the ultra-high electron\nconcentration needed in today's Si-based nanoelectronics."
    },
    {
        "anchor": "Kernel polynomial method to Anderson transition in disordered\n  $\u03b2$-graphyne: By means of variable moment kernel polynomial method, we analyze the\nlocalization properties of $\\beta$-graphyne sheet subjected to the Anderson\ndisorder. To detect the localization transition we focus on the scaling\nbehavior of the normalized typical density of states. We find that there takes\nplace a metal-insulator transition and the critical disorder strength is of the\norder of the bandwidth, which is contrary to the one-parameter scaling theory\nstating that for infinite two dimensional systems, all the electronic states\nare localized for an arbitrary strength of the Anderson disorder. As its\nparticular localization properties, it is reasonable to predict there will\nexist dc conductivity for $\\beta$-graphyne at zero temperature.",
        "positive": "Proposal for in situ Enhancement of Electron Spin Polarization in\n  Semiconductors: An extension of the original Overhauser effect to a more general\nnonequilibrium state was proposed by G. Feher, and demonstrated by Clark and\nFeher some forty years ago. It is suggested here that it might be possible to\nproduce excess electron spin polarization by allowing the role of the nuclei to\nbe played by other magnetic entities, such as paramagnetic impurities or\nadjacent magnetically ordered structures."
    },
    {
        "anchor": "Nonlinear photonics of fullerene solutions: Newly observed enhanced linear optical features of fullerene solutions (Raman\nscattering and one-photon luminescence) are due to clusterization of fullerene\nmolecules themselves as well as their composites with solvent molecules. A\ndirect connection between the enhanced linear effects and nonlinear behavior of\nthe solutions is discussed and empirical and computational tests of the\nsolutions nonlinear optics efficacy are suggested.",
        "positive": "Magnetocatalytic Adiabatic Spin Torque Orbital Transformations for Novel\n  Chemical and Catalytic Reaction Dynamics: The Little Effect: In this manuscript the theory and phenomena associated with the Little Effect\nare introduced as the spin induced orbital dynamics of confined fermions under\nstrong magnetic and thermal environments. This Little Effect is considered in\ndetails for the electron transfer reactions associated with redox processes of\nCu-Ag alloy within deionized water and for the orbital dynamics during the iron\ncatalyzed covalent bond rearrangements associated with amorphous carbon\nconversion to diamond. Furthermore, prolong extreme conditions of 74,000 amps,\n403 V, strong Lorentz compression, and thermal stresses upon this Cu-Ag- H2O\nsystem on the basis of the Little Effect of high spin, thermally induced\norbital dynamics are predicted and demonstrated to cause the magnetically\norganized reverse beta, electron capture, proton capture and neutron capture\nprocesses for various infrequent pycnonuclear transmutations within the Cu-Ag\ncoil. The general experimental verification and the broad implications of this\nLittle Effect on chemistry are demonstrated within these two ideal systems: an\nionic case and a molecular case. The Little Effect is contrasted with the\nHedvall Effect as a dynamical phenomenon causing the kinematics of the Hedvall\nEffect. The compatibility of the Little Effect with the Woodward-Hoffmann Rule\nis demonstrated. The Little Effect provides greater understanding of order in\nsystems far from equilibrium. The implications of the Little Effect for other\ninteresting phenomena such as ferromagnetism, unconventional magnetism,\nsuperparamagnetism, superconductivity, and pycnonuclear effects are concluded."
    },
    {
        "anchor": "AnisoGNN: graph neural networks generalizing to anisotropic properties\n  of polycrystals: We present AnisoGNNs -- graph neural networks (GNNs) that generalize\npredictions of anisotropic properties of polycrystals in arbitrary testing\ndirections without the need in excessive training data. To this end, we develop\nGNNs with a physics-inspired combination of node attributes and aggregation\nfunction. We demonstrate the excellent generalization capabilities of AnisoGNNs\nin predicting anisotropic elastic and inelastic properties of two alloys.",
        "positive": "Guaranteed convergence of the Kohn-Sham equations: A sufficiently damped iteration of the Kohn-Sham equations with the exact\nfunctional is proven to always converge to the true ground-state density,\nregardless of the initial density or the strength of electron correlation, for\nfinite Coulomb systems. We numerically implement the exact functional for\none-dimensional continuum systems and demonstrate convergence of the damped KS\nalgorithm. More strongly correlated systems converge more slowly."
    },
    {
        "anchor": "From the bulk to monatomic wires: An ab-initio study of magnetism in Co\n  systems with various dimensionality: A systematic ab-initio study within the framework of the local-spin-density\napproximation including spin-orbit coupling and an orbital-polarization term is\nperformed for the spin and orbital moments and for the X-ray magnetic circular\ndichroism (XMCD) spectra in hcp Co, in a Pt supported and a free standing Co\nmonolayer, and in a Pt supported and a free standing monatomic Co wire. When\nincluding the orbital-polarization term, the orbital moments increase\ndrastically when going to lower dimensionality, and there is an increasing\nasymmetry between the L_2 and L_3 XMCD signal. It is shown that spin and\norbital moments can be obtained with good accuracy from the XMCD spectra via\nthe sum rules. The <T_z> term of the spin sum rule is surprisingly small for\nthe wires, and the reason for this is discussed.",
        "positive": "Newly synthesized MAX phase Zr2SeC: DFT insights into physical\n  properties towards possible applications: A DFT study of the synthesized MAX phase Zr2SeC has been carried out for the\nfirst time to explore its physical properties for possible applications in many\nsectors. The studied properties are compared with prior known MAX phase Zr2SC.\nThe structural parameters (lattice constants, volume, and atomic positions) are\nobserved to be consistent with earlier results. The band structure and density\nof states (DOS) are used to explore the metallic conductivity, anisotropic\nelectrical conductivity, and the dominant role of Zr-d states to the electrical\nconductivity. Analysis of the peaks in the DOS and charge density mapping (CDM)\nof Zr2SeC and Zr2SC revealed the possible variation of the mechanical\nproperties and hardness among them. The mechanical stability has been checked\nusing elastic constants. The values of the elastic constants, elastic moduli\nand hardness parameters of Zr2SeC are found to be lowered than those of Zr2SC.\nThe anisotropic behavior of the mechanical properties has been studied and\nanalyzed. Technologically important thermodynamic properties such as the\nthermal expansion coefficient, Debye temperature, entropy, heat capacity at\nconstant volume, Gruneisen parameter along with volume and Gibbs free energy\nare investigated as a function of both temperature (0 to 1600 K) and pressure\n(0 to 50 GPa). Besides, the {\\Theta}D, minimum thermal conductivity (Kmin),\nmelting point (Tm), and {\\gamma} have also been calculated at room temperature\nand found to be lowered for Zr2SeC compared to Zr2SC owing to their close\nrelationship with the mechanical parameters. The value of the {\\Theta}D, Kmin,\nTm, and TEC suggest Zr2SeC as a thermal barrier coating material. The\ndielectric constant (real and imaginary part), refractive index, extinction\ncoefficient, absorption coefficient, photoconductivity, reflectivity, and loss\nfunction of Zr2SeC are computed and analyzed."
    },
    {
        "anchor": "A Perfect Lens for Ballistic Electrons: A Kane's Model: The analogy between electromagnetic waves and ballistic electrons within the\nKane's model is developed and subsequently applied to a theoretical description\nof a quantum version of a metamaterial planar lens. Restrictions imposed on the\nperfect lens and the poor man's lens by available semiconductor band structures\nare discussed. A realistic implementation is proposed for the quantum poor\nman's lens, which uses specific properties of the HgTe compound. The properties\nof the lens are presented on the basis of a calculated transmission of oblique\nelectrons through the lens structure.",
        "positive": "Anomalous magnetoresistance of EuB$_{5.99}$C$_{0.01}$: Enhancement of\n  magnetoresistance in systems with magnetic polarons: We present results of measurements of electrical, magnetic and thermal\nproperties of EuB$_{5.99}$C$_{0.01}$. The observed anomalously large negative\nmagnetoresistance as above, so below the Curie temperature of ferromagnetic\nordering $T_C$ is attributed to fluctuations in carbon concentration. Below\n$T_C$ the carbon richer regions give rise to helimagnetic domains, which are\nresponsible for an additional scattering term in the resistivity, which can be\nsuppressed by a magnetic field. Above $T_C$ these regions prevent the process\nof percolation of magnetic polarons (MPs), acting as \"spacers\" between MPs. We\npropose that such \"spacers\", being in fact volumes incompatible with existence\nof MPs, may be responsible for the decrease of the percolation temperature and\nfor the additional (magneto)resistivity increase in systems with MPs."
    },
    {
        "anchor": "Effect of different precursors on CVD growth of molybdenum disulfide: Control over thickness, size, and area of chemical vapor deposition (CVD)\ngrown molybdenum disulfide (MoS2) flakes is crucial for device application.\nHerein, we report a quantitative comparison of CVD synthesis of MoS2 on SiO2/Si\nsubstrate using three different precursors viz., molybdenum trioxide (MoO3),\nammonium heptamolybdate (AHM), and tellurium (Te). A three-step chemical\nreaction mechanism of evolution of MoS2 from MoO3 micro-crystals is proposed\nfor MoO3 precursor. Furthermore, a strategy based on growth temperature and\nratio of amount of precursors is developed to systematically control thickness\nand area of MoS2 flakes. Our findings show that for large-sized crystalline\nmonolayer MoS2 flakes, MoO3 is a better choice than AHM and Te-assisted\nsynthesis. Moreover, Te as growth promoter, can lower down growth temperature\nby 250C. This study can be further used to fabricate MoS2 based\nhigh-performance electronic devices such as photodetectors, thin film\ntransistors, and sensors.",
        "positive": "Frustration effects in magnetic molecules: Besides being a fascinating class of new materials, magnetic molecules\nprovide the opportunity to study concepts of condensed matter physics in zero\ndimensions. This contribution will exemplify the impact of molecular magnetism\non concepts of frustrated spin systems. We will discuss spin rings and the\nunexpected rules that govern their low-energy behavior. Rotational bands, which\nare experimentally observed in various molecular magnets, provide a useful,\nsimplified framework for characterizing the energy spectrum, but there are also\ndeviations thereof with far-reaching consequences. It will be shown that\nlocalized independent magnons on certain frustrated spin systems lead to giant\nmagnetization jumps, a new macroscopic quantum effect. In addition a\nfrustration-induced metamagnetic phase transitions will be discussed, which\ndemonstrates that hysteresis can exist without anisotropy. Finally, it is\ndemonstrated that frustrated magnetic molecules could give rise to an enhanced\nmagnetocaloric effect."
    },
    {
        "anchor": "Photonic Characterization of Oxygen and Air-Annealed Zn3N2 Thin Films: Zinc nitride films were synthesized by reactive radio frequency (rf)\nmagnetron sputtering of a zinc target using an Ar+N2 mixture. The as-deposited\nfilms were annealed in the air and O2 at 300 {\\deg}C for 1 hr. The XRD\nmeasurements indicated that the films had a polycrystalline structure with a\npreferred (400) Zn3N2 orientation. The annealing process enhanced the\ncrystallinity. After annealing, the AFM and SEM morphology revealed no\nsignificant change in the surface morphology and surface roughness. The direct\nbandgap of Zn3N2 was estimated to be in the range of 1.15 -1.35 eV where\nannealing resulted in a reduction of the bandgap. The films were confirmed to\nbe p-type conduction and the resistivity was slightly increased by annealing.\nThe photoconductivity measurements indicated that the as-deposited films did\nnot have any photoresponse, whereas the annealed films exhibited\nphotoconductivity.",
        "positive": "Ellipticity control of terahertz high-harmonic generation in a Dirac\n  semimetal: We report on terahertz high-harmonic generation in a Dirac semimetal as a\nfunction of the driving-pulse ellipticity and on a theoretical study of the\nfield-driven intraband kinetics of massless Dirac fermions.Very efficient\ncontrol of third-harmonic yield and polarization state is achieved in\nelectron-doped Cd$_3$As$_2$ thin films at room temperature. The observed\ntunability is understood as resulting from terahertz-field driven intraband\nkinetics of the Dirac fermions. Our study paves the way for exploiting\nnonlinear optical properties of Dirac matter for applications in signal\nprocessing and optical communications."
    },
    {
        "anchor": "Semimetallic Two-Dimensional Boron Allotrope with Massless Dirac\n  Fermions: It has been widely accepted that planar boron structures, composed of\ntriangular and hexagonal motifs are the most stable two dimensional (2D) phases\nand likely precursors for boron nanostructures. Here we predict, based on ab\ninitio evolutionary structure search, novel 2D boron structure with non-zero\nthickness, which is considerably, by 50 meV/atom lower in energy than the\nrecently proposed alpha-sheet structure and its analogues. In particular, this\nphase is identified for the first time to have a distorted Dirac cone, after\ngraphene and silicene the third elemental material with massless Dirac\nfermions. The buckling and coupling between the two sublattices not only\nenhance the energetic stability, but also are the key factors for the emergence\nof the distorted Dirac cone.",
        "positive": "A High Power Density, High Efficiency Hydrogen-Chlorine Regenerative\n  Fuel Cell with a Low Precious Metal Content Catalyst: We report the performance of a hydrogen-chlorine electrochemical cell with a\nchlorine electrode employing a low precious metal content alloy oxide\nelectrocatalyst for the chlorine electrode: (Ru_0.09Co_0.91)_3O_4. The cell\nemploys a commercial hydrogen fuel cell electrode and transports protons\nthrough a Nafion membrane in both galvanic and electrolytic mode. The peak\ngalvanic power density exceeds 1 W cm^-2, which is twice previous literature\nvalues. The precious metal loading of the chlorine electrode is below 0.15 mg\nRu cm^-2. Virtually no activation losses are observed, allowing the cell to run\nat nearly 0.4 W cm^-2 at 90% voltage efficiency. We report the effects of fluid\npressure, electrolyte acid concentration, and hydrogen-side humidification on\noverall cell performance and efficiency. A comparison of our results to the\nmodel of Rugolo et al. [Rugolo et al., J. Electrochem. Soc., 2012, 159, B133]\npoints out directions for further performance enhancement. The performance\nreported here gives these devices promise for applications in carbon\nsequestration and grid-scale electrical energy storage."
    },
    {
        "anchor": "Quasi-two-dimensional $S=1/2$ magnetism of\n  Cu[C$_6$H$_2$(COO)$_4$][C$_2$H$_5$NH$_3$]$_2$: We report structural and magnetic properties of the spin-$\\frac12$ quantum\nantiferromagnet Cu[C$_6$H$_2$(COO)$_4$][C$_2$H$_5$NH$_3$]$_2$ by means of\nsingle-crystal x-ray diffraction, magnetization, heat capacity, and electron\nspin resonance (ESR) measurements on polycrystalline samples, as well as\nband-structure calculations. The triclinic crystal structure of this compound\nfeatures CuO$_4$ plaquette units connected into a two-dimensional framework\nthrough anions of the pyromellitic acid [C$_6$H$_2$(COO)$_4$]$^{4-}$. The\nethylamine cations [C$_2$H$_5$NH$_3]^+$ are located between the layers and act\nas spacers. Magnetic susceptibility and heat capacity measurements establish a\nquasi-two-dimensional, weakly anisotropic and non-frustrated spin-$\\frac12$\nsquare lattice with the ratio of the couplings $J_a/J_c\\simeq 0.7$ along the\n$a$ and $c$ directions, respectively. No clear signatures of the long-range\nmagnetic order are seen in thermodynamic measurements down to 1.8\\,K. However,\nthe gradual broadening of the ESR line suggests that magnetic ordering occurs\nat lower temperatures. Leading magnetic couplings are mediated by the organic\nanion of the pyromellitic acid and exhibit a non-trivial dependence on the\nCu--Cu distance, with the stronger coupling between those Cu atoms that are\nfurther apart.",
        "positive": "Cavity control of nonlinear phononics: Nonlinear interactions between phonon modes govern the behavior of\nvibrationally highly excited solids and molecules. Here, we demonstrate\ntheoretically that optical cavities can be used to control the redistribution\nof energy from a highly excited coherent infrared-active phonon state into the\nother vibrational degrees of freedom of the system. The hybridization of the\ninfrared-active phonon mode with the fundamental mode of the cavity induces a\npolaritonic splitting that we use to tune the nonlinear interactions with other\nvibrational modes in and out of resonance. We show that not only can the\nefficiency of the redistribution of energy be enhanced or decreased, but also\nthe underlying scattering mechanisms may be changed. This work introduces the\nconcept of cavity control to the field of nonlinear phononics, enabling\nnonequilibrium quantum optical engineering of new states of matter."
    },
    {
        "anchor": "Spin projection and spin current density within relativistic electronic\n  transport calculations: A spin projection scheme is presented which allows the decomposition of the\nelectric conductivity into two different spin channels within fully\nrelativistic $ab$ $initio$ transport calculations that account for the impact\nof spin-orbit coupling. This is demonstrated by calculations of the\nspin-resolved conductivity of Fe$_{1-x}$Cr$_x$ and Co$_{1-x}$Pt$_x$ disordered\nalloys on the basis of the corresponding Kubo-Greenwood equation implemented\nusing the Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA)\nband structure method. In addition, results for the residual resistivity of\ndiluted Ni-based alloys are presented that are compared to theoretical and\nexperimental ones that rely on Mott's two-current model for spin-polarized\nsystems. The application of the scheme to deal with the spin-orbit induced spin\nHall effect is discussed in addition.",
        "positive": "Application of Ultraviolet Fluorescence in Wafer Surface Cleaning\n  Analysis: Ultraviolet fluorescence (UVF) is introduced as a novel and versatile method\nfor the determination of the contamination of metal impurities on silicon wafer\nsurfaces. The results given demonstrate the usefulness of UVF for contamination\ncontrol in silicon wafer processing. The experiments show some main\ncharacteristic peaks such as Fe, Cu, Ni and Na at room temperature. Compared\nwith other surface sensitive techniques, the main advantages of UVF are low\ndetection limits, simultaneous multi-element analysis and high sensitivity (up\nto 109 Fe/cm2)."
    },
    {
        "anchor": "Chrono CDI: Coherent diffractive imaging of time-evolving samples: Bragg coherent x-ray diffractive imaging is a powerful technique for\ninvestigating dynamic nanoscale processes in nanoparticles immersed in\nreactive, realistic environments. Its temporal resolution is limited, however,\nby the oversampling requirements of 3D phase retrieval. Here we show that\nincorporating the entire measurement time series, which is typically a\ncontinuous physical process, into phase retrieval allows the oversampling\nrequirement at each time step to be reduced leading to a subsequent improvement\nin the temporal resolution by a factor of 2 to 20 times. The increased time\nresolution will allow imaging of faster dynamics and of radiation dose\nsensitive samples. This approach, which we call \"chrono CDI\", may find use in\nimproving time resolution in other imaging techniques.",
        "positive": "Electrical spin injection and detection in Germanium using three\n  terminal geometry: In this letter, we report on successful electrical spin injection and\ndetection in \\textit{n}-type germanium-on-insulator (GOI) using a\nCo/Py/Al$_{2}$O$_{3}$ spin injector and 3-terminal non-local measurements. We\nobserve an enhanced spin accumulation signal of the order of 1 meV consistent\nwith the sequential tunneling process via interface states in the vicinity of\nthe Al$_{2}$O$_{3}$/Ge interface. This spin signal is further observable up to\n220 K. Moreover, the presence of a strong \\textit{inverted} Hanle effect points\nat the influence of random fields arising from interface roughness on the\ninjected spins."
    },
    {
        "anchor": "Internal Length Gradient (ILG) Material Mechanics Across Scales &\n  Disciplines: A combined theoretical/numerical/experimental program is outlined for\nextending the ILG approach to consider time lags, stochasticity and\nmultiphysics couplings. Through this extension it is possible to discuss the\ninterplay between deformation internal lengths (ILs) and ILs induced by\nthermal, diffusion or electric field gradients. Size-dependent multiphysics\nstability diagrams are obtained, and size-dependent serrated stress-strain\ncurves are interpreted through combined gradient-stochastic models. When\ndifferential equations are not available for describing material behavior, a\nTsallis non-extensive thermodynamic formulation is employed to characterize\nstatistical properties. A novel multiscale coarse graining technique, the\nequation free method (EFM), is suggested for bridging length scales, and the\nsame is done for determining ILs through novel laboratory tests by employing\nspecimens with fabricated gradient micro/nano structures. Three emerging\nresearch areas are discussed: (i) Plastic instabilities and size effects in\nnanocrystalline (NC)/ultrafine grain (UFG) and bulk metallic glass (BMG)\nmaterials; (ii) Chemomechanical damage, electromechanical degradation, and\nphotomechanical aging in energetic materials; (iii) Brain tissue and neural\ncell modeling. Finally, a number of benchmark problems are considered in more\ndetail. They include gradient chemoelasticity for Li-ion battery electrodes;\ngradient piezoelectric and flexoelectric materials; elimination of\nsingularities from crack tips; derivation of size-dependent stability diagrams\nfor shear banding in BMGs; modeling of serrated size-dependent stress-strain\ncurves in micro/nanopillars; description of serrations and multifractal\npatterns through Tsallis q-statistics; and an extension of gradient\nelasticity/plasticity models to include fractional derivatives and fractal\nmedia.",
        "positive": "How Gold nanoparticle acquires magnetism? - Formation of large orbital\n  moment at the interface: In this paper, we have tried to find out the origin of magnetism in Gold\nnanoparticles (Au- NPs). We observe that upon incorporating Gold nanoparticles\n(Au-NPs) in Fe3O4 nanoparticle medium the net magnetisation increases compared\nto the pure Fe3O4 nanoparticle medium. This increase of magnetization can be\nattributed to the large orbital magnetic moment formation at the Au/magnetic\nparticle interface indicating that magnetism observed in Au-NPs is an\ninterfacial effect. This interfacial effect has been supported by the\nobservation of sudden transition from positive saturated magnetisation to a\nnegative diamagnetic contribution as a function of magnetic field on citrate\ncoated gold Au-NPs."
    },
    {
        "anchor": "Phonons and thermal transport in Si/SiO$_2$ multishell nanotubes:\n  Atomistic study: Thermal transport in the Si/SiO$_2$ multishell nanotubes is investigated\ntheoretically. The phonon energy spectra are obtained using the atomistic\nLattice Dynamics approach. Thermal conductivity is calculated using the\nBoltzmann transport equation within the relaxation time approximation.\nRedistribution of the vibrational spectra in multishell nanotubes leads to a\ndecrease of the phonon group velocity and the thermal conductivity as compared\nto homogeneous Si nanowires. Phonon scattering on the Si/SiO$_2$ interfaces is\nanother key factor of strong reduction of the thermal conductivity in these\nstructures (down to 0.2 W/mK at room temperature). We demonstrate that phonon\nthermal transport in Si/SiO$_2$ nanotubes can be efficiently suppressed by a\nproper choice of nanotube's geometrical parameters: lateral cross-section,\nthickness and number of shells.",
        "positive": "Dynamics of a dislocation bypassing an impenetrable precipitate: the\n  Hirsch mechanism revisited: Dynamical process where an edge dislocation in fcc copper bypasses an\nimpenetrable precipitate is investigated by means of molecular dynamics\nsimulation. A mechanism which is quite different from the Orowan mechanism is\nobserved, where a dislocation leaves two prismatic loops near a precipitate:\ni.e. the Hirsch mechanism. It is found that the critical stress for the Hirsch\nmechanism is almost the same with the Orowan stress, while the spatial\ninhomogeneity of the shear stress is essential to the Hirsch mechanism. We also\nfind that the repetition of the Hirsch mechanism does not increase the critical\nstress."
    },
    {
        "anchor": "Strain effect in silicon-on-insulator materials: Investigation with\n  optical phonons: We report a detailed experimental and theoretical investigation of the effect\nof residual strain, and strain relaxation, which manifests itself at the\nSi/SiO$_{2}$ interfaces in commercial silicon-on-insulator (SOI) wafers. SOI\nmaterial is made of a single-crystal silicon overlayer (SOL) on top of an\ninsulator (buried SiO$_{2}$ layer) sitting on a handle silicon wafer. Infrared\nreflectivity spectra show that the buried SiO$_{2}$ layer relaxes continuously\nwhen thinning the SOL. At the same time the SOL surface roughness and the\nlinewidth of optical phonons in Si near the Si/SiO$_2$ interface (probed by\nmicro-Raman specroscopy) increase. In the as-delivered wafers, this comes from\na slight expansion of Si on both sides of the buried SiO$_{2}$ layer which,\nconversely, is compressed. Thinning the SOL modifies these initial equilibrium\nconditions. To get quantitative results, we have modeled all our Raman spectra\nusing a theory of inhomogeneous shift and broadening for optical phonons, which\ntakes into account the phonon interaction with the static strain fluctuations.\n  From the variation of linewidth versus interface distance, we have found that\nthe mean squared strain continues to relax in the bulk of the wafer through a\ndepth on the order of several $\\mu m$. We also show that the SOL surface\nroughness is related to strain fluctuations near the Si/SiO$_2$ interfaces.",
        "positive": "Bistability and noise-enhanced velocity of rolling motion: We investigate the motion of a hard cylinder rolling down a soft inclined\nplane. The cylinder is subjected to a viscous drag force and stochastic\nfluctuations due to the surrounding medium. In a wide range of parameters we\nobserve bistability of the rolling velocity. In dependence on the parameters,\nincreasing noise level may lead to increasing or decreasing average velocity of\nthe cylinder. The approximative analytical theory agrees with numerical\nresults."
    },
    {
        "anchor": "Multiscale Modeling of Materials - Concepts and Illustration: The approximate representation of a quantum solid as an equivalent composite\nsemi-classical solid is considered for insulating materials. The composite is\ncomprised of point ions moving on a potential energy surface. In the classical\nbulk domain this potential energy is represented by pair potentials constructed\nto give the same structure and elastic properties as the underlying quantum\nsolid. In a small local quantum domain the potential is determined from a\ndetailed quantum calculation of the electronic structure. The primary new\ningredients are 1) a determination of the pair potential from quantum data for\nequilibrium and strained structures, 2) development of pseudo-atoms for a\nrealistic treatment of charge densities where bonds have been broken to define\nthe quantum domain, and 3) inclusion of polarization effects on the quantum\ndomain due to its environment. This formal structure is illustrated in detail\nfor an silica nanorod. For each configuration considered, the charge density of\nthe entire solid is calculated quantum mechanically to provide the reference by\nwhich to judge the accuracy of the modeling.It is then shown that the quantum\nrod, the rod constructed from the classical pair potentials, and the composite\nclassical/quantum rod all have the same equilibrium structure and response to\nelastic strain. The accuracy of the modeling is shown to apply for two quite\ndifferent quantum chemical methods for the underlying quantum mechanics:\ntransfer Hamiltonian and density functional methods.",
        "positive": "Crystal Structure and Chemistry of Topological Insulators: Topological surface states, a new kind of electronic state of matter, have\nrecently been observed on the cleaved surfaces of crystals of a handful of\nsmall band gap semiconductors. The underlying chemical factors that enable\nthese states are crystal symmetry, the presence of strong spin orbit coupling,\nand an inversion of the energies of the bulk electronic states that normally\ncontribute to the valence and conduction bands. The goals of this review are to\nbriefly introduce the physics of topological insulators to a chemical audience\nand to describe the chemistry, defect chemistry, and crystal structures of the\ncompounds in this emergent field."
    },
    {
        "anchor": "A composite ansatz for the calculation of dynamical structure factor: We propose an ansatz without adjustable parameters for the calculation of\ndynamical structure factor. The ansatz combines quasi-particle Green's\nfunction, especially the contribution from the renormalization factor, and the\nexchange-correlation kernel from time-dependent density functional theory\ntogether, verified for typical metals and semiconductors from plasmon\nexcitation regime to Compton scattering regime. It has the capability to\nreconcile both small-angle and large-angle x-ray scattering (IXS) signals with\nmuch improved accuracy, which can be used, as the theoretical base model, in\ninversely inferring electronic structures of condensed matter from IXS\nexperimental signals directly. It may also used to diagnose thermal parameters,\nsuch as temperature and density, of dense plasmas in x-ray Thomson scattering\nexperiments.",
        "positive": "Piezo films with adjustable anisotropic strain for bending actuators\n  with tunable bending profiles: We present a method to produce in-plane polarized piezo films with a freely\nadjustable ratio of the strains in orthogonal in-plane directions. They can be\nused in piezo bending actuators with a tunable curvature profile. The strains\nare obtained as mean strains from a periodic polarization pattern produced by a\nsuitable doubly interdigitated electrode structure. This mechanism is\ndemonstrated for several examples using PZT sheets. We further discuss how this\ntuning and the parameters of the electrode layout affect the overall magnitude\nof the displacement."
    },
    {
        "anchor": "Half-Heusler Topological Insulators: A First-Principle Study with the\n  Tran-Blaha Modified Becke-Johnson Density Functional: We systematically investigate the topological band structures of half-Heusler\ncompounds using first-principles calculations. The modified Becke-Johnson\nexchange potential together with local density approximation for the\ncorrelation potential (MBJLDA) has been used here to obtain accurate band\ninversion strength and band order. Our results show that a large number of\nhalf-Heusler compounds are candidates for three-dimensional topological\ninsulators. The difference between band structures obtained using the local\ndensity approximation (LDA) and MBJLDA potential is also discussed.",
        "positive": "Understanding the Effects of Dielectric Property, Separation Distance,\n  and Band Alignment on Interlayer Excitons in 2D Hybrid MoS2/WSe2\n  Heterostructures: Two dimensional (2D) van der Waals heterostructures from transition metal\ndichalcogenide (TMDC) semiconductors show a new class of spatially separate\nexcitons with extraordinary properties. The interlayer excitons (XI) have been\nstudied extensively, yet the mechanisms that modulate XI are still not well\nunderstood. Here, we introduce several organic-layer-embedded hybrid\nheterostructures, MoS2/organic/WSe2, to study the binding energy of XI. We\ndiscover that the dielectric screening of the quasi-particle is reduced with\norganic molecules due to decreased dielectric constant and greater separation\ndistance between the TMDC layers. As a result, a distinct blueshift is observed\nin interlayer emission. We also find that the band alignment at the\nheterointerface is critical. When the organic layer provides a staggered energy\nstate, interlayer charge transfer can transition from tunneling to\nband-assisted transfer, further increasing XI emission energies due to a\nstronger dipolar interaction. The formation of XI may also be significantly\nsuppressed with electron or hole trapping molecules. These findings should be\nuseful in realizing XI-based optoelectronics."
    },
    {
        "anchor": "Thermal conductivity of bulk In$_{2}$O$_{3}$ single crystals: The transparent semiconductor In$_{2}$O$_{3}$ is a technologically important\nmaterial. It combines optical transparency in the visible frequency range and\nsizeable electric conductivity. We present a study of thermal conductivity of\nIn$_{2}$O$_{3}$ crystals and find that around 20 K, it peaks to a value as high\nas 5,000 WK$^{-1}$m$^{-1}$, comparable to the peak thermal conductivity in\nsilicon and exceeded only by a handful of insulators. The amplitude of the peak\ndrastically decreases in presence of a type of disorder, which does not simply\ncorrelate with the density of mobile electrons. Annealing enhances the ceiling\nof the phonon mean free path. Samples with the highest thermal conductivity are\nthose annealed in the presence of hydrogen. Above 100 K, thermal conductivity\nbecomes sample independent. In this intrinsic regime, dominated by\nphonon-phonon scattering, the magnitude of thermal diffusivity, $D$ becomes\ncomparable to many other oxides, and its temperature dependence evolves towards\n$T^{-1}$. The ratio of $D$ to the square of sound velocity yields a scattering\ntime which obeys the expected scaling with the Planckian time.",
        "positive": "Disentangling amplitude and phase dynamics of a charge density wave in a\n  photo-induced phase transition: Upon excitation with an intense ultrafast laser pulse, a symmetry-broken\nground state can undergo a non-equilibrium phase transition through pathways\ndissimilar from those in thermal equilibrium. Determining the mechanism\nunderlying these photo-induced phase transitions (PIPTs) has been a\nlong-standing issue in the study of condensed matter systems. To this end, we\ninvestigate the light-induced melting of a unidirectional charge density wave\n(CDW) material, LaTe$_3$. Using a suite of time-resolved probes, we\nindependently track the amplitude and phase dynamics of the CDW. We find that a\nquick ($\\sim\\,$1$\\,$ps) recovery of the CDW amplitude is followed by a slower\nreestablishment of phase coherence. This longer timescale is dictated by the\npresence of topological defects: long-range order (LRO) is inhibited and is\nonly restored when the defects annihilate. Our results provide a framework for\nunderstanding other PIPTs by identifying the generation of defects as a\ngoverning mechanism."
    },
    {
        "anchor": "Enhanced thermoelectricity at the ultra-thin film limit: At the ultra-thin film limit, quantum confinement strongly improves\nthermoelectric figure of merit in materials such as Sb$_2$Te$_3$ and\nBi$_2$Te$_3$. These high quality films have only been realized using well\ncontrolled techniques such as molecular beam epitaxy. We report a two fold\nincrease in the Seebeck coefficient for both p-type Sb$_2$Te$_3$ and n-type\nBi$_2$Te$_3$ using thermal co-evaporation, an affordable approach. At the thick\nfilm limit greater than 100 nm, their Seebeck coefficients are around 100 $\\mu\nV/K$, similar to results obtained in other work. When the films are thinner\nthan 50 nm, the Seebeck coefficient increases to about 500 $\\mu V/K$. With a\ntotal Seebeck coefficient $\\sim$ 1 mV/K and an estimate ZT $\\sim$ 2, this pair\nof materials is the first step to a practical micro-cooler at room temperature.",
        "positive": "Influence of surface tension on the conical miniscus of a magnetic fluid\n  in the field of a current-carrying wire: We study the influence of surface tension on the shape of the conical\nminiscus built up by a magnetic fluid surrounding a current-carrying wire.\nMinimization of the total energy of the system leads to a singular second order\nboundary value problem for the function $\\zeta(r)$ describing the axially\nsymmetric shape of the free surface. An appropriate transformation regularizes\nthe problem and allows a straightforward numerical solution. We also study the\neffects a superimposed second liquid, a nonlinear magnetization law of the\nmagnetic fluid, and the influence of the diameter of the wire on the free\nsurface profile."
    },
    {
        "anchor": "Role of Polaron Pair Diffusion and Surface Losses in Organic\n  Semiconductor Devices: By applying Monte Carlo simulations we found that the extraction of bound\npolaron pairs (PP) at the electrodes is an important loss factor limiting the\nefficiency of organic optoelectronic and photovoltaic devices. Based upon this\nfinding, we developed a unified analytic model consisting of exact Onsager\ntheory, describing the dissociation of PP in organic donor-acceptor\nheterojunctions, the Sokel-Hughes model for the extraction of free polarons at\nthe electrodes, as well as of PP diffusion leading to the aforementioned loss\nmechanism, which was not considered previously. Our approach allows to describe\nthe simulation details on a macroscopic scale and to gain fundamental insights,\nwhich is important in view of developing an optimized photovoltaic device\nconfiguration.",
        "positive": "Contributions of Al and Ni segregation to the interfacial cohesion of\n  Cu-rich precipitates in ferritic steels: We characterise the influence of the segregation behaviours of two typical\nalloying elements, aluminium and nickel, on the interfacial cohesive properties\nof copper-rich precipitates in ferritic steels, with a view towards\nunderstanding steel embrittlement. The first-principles method is used to\ncompute the energetic and bonding properties of aluminium and nickel at the\ninterfaces of the precipitates and corresponding fracture surfaces. Our results\nshow the segregation of aluminium and nickel at interfaces of precipitates are\nboth energetically favourable. We find that the interfacial cohesion of copper\nprecipitates is enhanced by aluminium segregation but reduced by nickel\nsegregation. Opposite roles can be attributed to the different symmetrical\nfeatures of the valence states for aluminium and nickel. The nickel-induced\ninterfacial embrittlement of copper-rich precipitates increase the\nductile-brittle transition temperature (DBTT) of ferritic steels and provides\nan explanation of many experimental phenomena, such as the fact that the shifts\nof DBTT of reactor pressure vessel steels depend the copper and nickel content."
    },
    {
        "anchor": "Spatially resolved ultrafast precessional magnetization reversal: Spatially resolved measurements of quasi-ballistic precessional magnetic\nswitching in a microstructure are presented. Crossing current wires allow\ndetailed study of the precessional switching induced by coincident longitudinal\nand transverse magnetic field pulses. Though the response is initially\nspatially uniform, dephasing occurs leading to nonuniformity and transient\ndemagnetization. This nonuniformity comes in spite of a novel method for\nsuppression of end domains in remanence. The results have implications for the\nreliability of ballistic precessional switching in magnetic devices.",
        "positive": "Metal nanoparticle field-effect transistor: We demonstrate that by means of a local top-gate current oscillations can be\nobserved in extended, monolayered films assembled from monodisperse metal\nnanocrystals -- realizing transistor function. The oscillations in this\nmetal-based system are due to the occurrence of a Coulomb energy gap in the\nnanocrystals which is tunable via the nanocrystal size. The nanocrystal\nassembly by the Langmuir-Blodgett method yields homogeneous monolayered films\nover vast areas. The dielectric oxide layer protects the metal nanocrystal\nfield-effect transistors from oxidation and leads to stable function for\nmonths. The transistor function can be reached due to the high monodispersity\nof the nanocrystals and the high super-crystallinity of the assembled films.\nDue to the fact that the film consists of only one monolayer of nanocrystals\nand all nanocrystals are simultaneously in the state of Coulomb blockade the\nenergy levels can be influenced efficiently (limited screening)."
    },
    {
        "anchor": "Toroidal moments as indicator for magneto-electric coupling: the case of\n  BiFeO_3 versus FeTiO_3: In this paper we present an analysis of the magnetic toroidal moment and its\nrelation to the various structural modes in R3c-distorted perovskites with\nmagnetic cations on either the perovskite A or B site. We evaluate the toroidal\nmoment in the limit of localized magnetic moments and show that the full\nmagnetic symmetry can be taken into account by considering small induced\nmagnetic moments on the oxygen sites. Our results give a transparent picture of\nthe possible coupling between magnetization, electric polarization, and\ntoroidal moment, thereby highlighting the different roles played by the various\nstructural distortions in multiferroic BiFeO_3 and in the recently discussed\nisostructural material FeTiO_3, which has been predicted to exhibit electric\nfield-induced magnetization switching.",
        "positive": "Ultralong Lifetime Plasmons on Picosecond Time Scale Enabled by Hybrid\n  Plasmon-Phonon Polaritons: Graphene plasmonics is of great interest for compact optical devices working\nin broad frequency domains with ultrahigh speed and very low energy\nconsumption. However, graphene plasmons damp out quickly on most substrates\nmainly due to scattering loss from substrate surface phonons and impurities.\nHere we discover a new hybridized plasmon-phonon polariton mode in\ngraphene/h-BN van der Waals heterostructures, which enables ultralong hybrid\nplasmon lifetime up to 1.6 picosecond, the longest plasmon lifetime ever\ndemonstrated. Such remarkably long lifetime arises from the coupling of\nlong-lifetime h-BN transverse optical phonon with graphene plasmons, which\nuniquely exists in monolayer heterostructures. Our findings and understanding\nof this unexploited hybrid mode offer a novel approach to tune the plasmon\nbehaviours in the frequency, time and space domains. This can potentially\nintroduce a new paradigm to generate highly-confined plasmons with ultra-long\nlifetime for various applications, such as deep-subwavelength metamaterials,\nultra-low-loss waveguides, and ultrafast optical switches."
    },
    {
        "anchor": "Possible magnetic states in buckybowl molecules: Possible magnetic properties are studied in the buckybowl molecules: the\nsumanene and a part of C_60. The Hubbard model is applied to the systems. We\nfind that the molecular structure determines the magnetism in the sumanene. On\nthe other hand, the edge state is found along the zigzag edge of a part of\nC_60. Therefore, the novel property, transition from molecular magnetism to the\nmagnetism like in nanographene, is found.",
        "positive": "Signature of Many-Body Localization of Phonons in Strongly Disordered\n  Superlattices: Many-body localization (MBL) has attracted significant attention due to its\nimmunity to thermalization, role in logarithmic entanglement entropy growth,\nand opportunities to reach exotic quantum orders. However, experimental\nrealization of MBL in solid-state systems has remained challenging. Here we\nreport evidence of a possible phonon MBL phase in disordered GaAs/AlAs\nsuperlattices. Through grazing-incidence inelastic X-ray scattering, we observe\na strong deviation of the phonon population from equilibrium in samples doped\nwith ErAs nanodots at low temperature, signaling a departure from\nthermalization. This behavior occurs within finite phonon energy and wavevector\nwindows, suggesting a localization-thermalization crossover. We support our\nobservation by proposing a theoretical model for the effective phonon\nHamiltonian in disordered superlattices, and showing that it can be mapped\nexactly to a disordered 1D Bose-Hubbard model with a known MBL phase. Our work\nprovides momentum-resolved experimental evidence of phonon localization,\nextending the scope of MBL to disordered solid-state systems."
    },
    {
        "anchor": "Ab initio modeling and experimental investigation of Fe$_2$P by DFT and\n  spin spectroscopies: Fe$_2$P alloys have been identified as promising candidates for magnetic\nrefrigeration at room-temperature and for custom magnetostatic applications.\nThe intent of this study is to accurately characterize the magnetic ground\nstate of the parent compound, Fe$_2$P, with two spectroscopic techniques,\n$\\mu$SR and NMR, in order to provide solid bases for further experimental\nanalysis of Fe$_2$P-type transition metal based alloys. We perform zero applied\nfield measurements using both techniques below the ferromagnetic transition\n$T_C=220~\\mathrm K$. The experimental results are reproduced and interpreted\nusing first principles simulations validating this approach for quantitative\nestimates in alloys of interest for technological applications.",
        "positive": "Why ferromagnetic semiconductors?: Rapid development of information technologies originates from the exponential\nincrease in the density of information that can be processed, stored, and\ntransfer by the unit area of relevant devices. There is, however, a growing\namount of evidences that the progress achieved in this way approaches its\nlimits. Various novel ideas put forward to circumvent barriers ahead are\ndescribed. Particular attention is paid to those concepts which propose to\nexploit electron or nuclear spins as the information carriers. Here,\nferromagnetic semiconductors of III-V or II-VI compounds containing a sizable\nconcentration of transition metals appear as outstanding spintronic materials."
    },
    {
        "anchor": "Is the pinning of ordinary dislocations in gamma-TiAl intrinsic or\n  extrinsic in nature? A combined atomistic and kinetic Monte Carlo approach: We address the question of the observed pinning of 1/2 <110] ordinary screw\ndislocations in gamma-TiAl which leads to the characteristic trailing of\ndipoles in the microstructure. While it has been proposed that these may be\nvariously intrinsic or extrinsic in nature, we are able to rule out the former\nmechanism. We do this by means of very large scale, three dimensional atomistic\nsimulations using the quantum mechanical bond order potential. We find that the\nkink-pair formation energy is large: 6eV, while the single kink migration\nenergy is conversely very small: 0.13eV. Using these, and other atomistically\nderived data, we make kinetic Monte Carlo simulations at realistic time and\nlength scales to simulate dislocation mobility as a function of stress and\ntemperature. In the temperature range of the stress anomaly in gamma-TiAl, we\ndetermine whether one or several of the pinning and unzipping processes\nassociated with generation of jogs are observed during our simulations. We\nconclude that the pinning of ordinary dislocations and anomalous mechanical\nbehaviour in gamma-TiAl must be attributed to a combination of extrinsic\nobstacles and extensive cross-slip in a crystal containing impurities.",
        "positive": "Electronic band gaps from Quantum Monte Carlo methods: We develop a method for calculating the fundamental electronic gap of\nsemiconductors and insulators using grand canonical Quantum Monte Carlo\nsimulations. We discuss the origin of the bias introduced by supercell\ncalculations of finite size and show how to correct the leading and subleading\nfinite size errors either based on observables accessible in the finite-sized\nsimulations or from DFT calculations. Our procedure is applied to solid\nmolecular hydrogen and compared to experiment for carbon and silicon crystals."
    },
    {
        "anchor": "Tunneling magnetoresistance in devices based on epitaxial NiMnSb with\n  uniaxial anisotropy: We demonstrate tunnel magnetoresistance (TMR) junctions based on a tri layer\nsystem consisting of an epitaxial NiMnSb, aluminum oxide and CoFe tri layer.\nThe junctions show a tunnelling magnetoresistance of Delta R/R of 8.7% at room\ntemperature which increases to 14.7% at 4.2K. The layers show clear separate\nswitching and a small ferromagnetic coupling. A uniaxial in plane anisotropy in\nthe NiMnSb layer leads to different switching characteristics depending on the\ndirection in which the magnetic field is applied, an effect which can be used\nfor sensor applications.",
        "positive": "Accurate electronic band gap of pure and functionalized graphane from GW\n  calculations: Using the GW approximation, we study the electronic structure of the recently\nsynthesized hydrogenated graphene, named graphane. For both conformations, the\nminimum band gap is found to be direct at the $\\Gamma$ point, and it has a\nvalue of 5.4 eV in the stable chair conformation, where H atoms attach C atoms\nalternatively on opposite sides of the two dimensional carbon network. In the\nmeta-stable boat conformation the energy gap is 4.9 eV. Then, using a supercell\napproach, the electronic structure of graphane was modified by introducing\neither an hydroxyl group or an H vacancy. In this last case, an impurity state\nappears at about 2 eV above the valence band maximum."
    },
    {
        "anchor": "Halogenation Thermodynamics of Pyrrolidinium-Based Ionic Liquids: Room-temperature ionic liquids (RTILs) exhibit large difference between\nmelting and boiling points. They are highly tunable thanks to numerous\naccessible combinations of the cation and the anion. On top of that, cations\ncan be functionalized using methods of organic chemistry. This paper reports\ngas-phase thermodynamics (enthalpy, entropy, Gibbs free energy) of the\nhalogenation reactions (fluorination, chlorination, bromination) involving\nprotonated pyrrolidine C4H10N+, protic N-ethylpyrrolidinium C4H9N(C2H5)+, and\naprotic N-ethyl-N-methylpyrrolidinium C4H8N(CH3)(C2H5)+ cations. Substitution\nof all symmetrically non-equivalent hydrogen atoms was compared based of the\nthermodynamic favorability. Fluorination of all sites is much more favorable\nthan chlorination, whereas chlorination is somewhat more favorable than\nbromination. This is not trivial, since electronegative fluorine and chlorine\nhave to compete for the already insufficient number of electrons with other\natoms belonging to the pyrrolidinium-based cations. The difference between\ndifferent reaction sites within the cations is modest, although it often\nexceeds kT at simulated temperatures. The correlation between thermodynamics\nand electronic density distribution has been established, which allows new\nsimple prediction of the reaction pathways. The reported results inspire\nfurther chemical modifications of the pyrrolidinium-based RTILs to achieve ever\nfiner tunability of physical chemical properties.",
        "positive": "Quantum transport in quasicrystals and complex metallic alloys: The semi-classical Bloch-Boltzmann theory is at the heart of our\nunderstanding of conduction in solids, ranging from metals to semi-conductors.\nPhysical systems that are beyond the range of applicability of this theory are\nthus of fundamental interest. This is the case of disordered systems which\npresent quantum interferences in the diffusive regime, i.e. Anderson\nlocalization effects. It appears that in quasicrystals and related complex\nmetallic alloys another type of breakdown of the semi-classical Bloch-Boltzmann\ntheory operates. This type of quantum transport is related to the specific\npropagation mode of electrons in these systems. We develop a theory of quantum\ntransport that applies to a normal ballistic law but also to these specific\ndiffusion laws. As we show phenomenological models based on this theory\ndescribe correctly the experimental transport properties. Ab-initio\ncalculations performed on approximants confirm also the validity of this\nanomalous quantum diffusion scheme. Although the present chapter focuses on\nelectrons in quasicrystals and complex metallic alloys, the concept that are\ndeveloped here can be useful for phonons in these systems. There is also a deep\nanalogy between the type of quantum transport described here and the conduction\nproperties of other systems where charge carriers are also slow, such as some\nheavy fermions or polaronic systems."
    },
    {
        "anchor": "Ab initio investigation of lattice dynamics of fluoride scheelite LiYF4: We report on the phonon dynamics of LiYF4 obtained by direct method using\nfirst principle calculations. The agreement between experimental and calculated\nmodes is satisfactory. An inversion between two Raman active modes is noticed\ncompared to inelastic neutron scattering and Raman measurements. The atomic\ndisplacements corresponding to these modes are discussed. Multiple inversions\nbetween Raman and infrared active groups are present above 360 cm-1. The total\nand partial phonon density of state is also calculated and analyzed.",
        "positive": "Sound modes broadening in quasicrystals: We propose a simple phenomenological model to analyze vibrational\ncharacteristics of quasicrystals (QCs). The interpretation of the obtained\nrecently data is based on the existence of almost dispersionless optical modes\nmost probably related to the specific clusters which constitute the\ncharacteristic building blocks of any QC structure. We generalize to QCs the\nwell - known Akhiezer mechanism, which in our case is related to a ''long\nwave'' disturbance of the quasicrystalline optical modes by the propagating\nsound modes. At higher wave vectors strong hybridization of acoustic and\noptical modes takes place, and it leads to a more steep broadening dependence\non wave vectors, and besides the excitation can no longer be described as a\nsingle acoustic mode with a well defined wave vector."
    },
    {
        "anchor": "Molecular Beam Epitaxy growth of MoTe$_2$ on Hexagonal Boron Nitride: Hexagonal boron nitride has already been proven to serve as a decent\nsubstrate for high quality epitaxial growth of several 2D materials, such as\ngraphene, MoSe$_{\\tiny{\\textrm{2}}}$, MoS$_{\\tiny{\\textrm{2}}}$ or\nWSe$_{\\tiny{\\textrm{2}}}$. Here, we present for the first time the molecular\nbeam epitaxy growth of MoTe$_{\\tiny{\\textrm{2}}}$ on atomically smooth\nhexagonal boron nitride (hBN) substrate. Occurrence of\nMoTe$_{\\tiny{\\textrm{2}}}$ in various crystalline phases such as distorted\noctahedral 1T' phase with semimetal properties or hexagonal 2H phase with\nsemiconducting properties opens a possibility of realisation of crystal-phase\nhomostructures with tunable properties. Atomic force microscopy studies of\nMoTe$_{\\tiny{\\textrm{2}}}$ grown in a single monolayer regime enable us to\ndetermine surface morphology as a function of the growth conditions. The\ndiffusion constant of MoTe$_{\\tiny{\\textrm{2}}}$ grown on hBN can be altered 5\ntimes by annealing after the growth, reaching about 5 $\\cdot$ 10$^{-6}$\ncm$^{2}$/s. Raman spectroscopy results suggest a coexistence of both 2H and 1T'\nMoTe$_{\\tiny{\\textrm{2}}}$ phases in the studied samples.",
        "positive": "Structural heterogeneity and diffuse scattering in morphotropic lead\n  zirconate-titanate single crystals: Complementary diffuse and inelastic synchrotron X-ray scattering measurements\nof lead zirconate-titanate single crystals with composition near the\nmorphotropic phase boundary (x=0.475) are reported. In the temperature range\n293 K < T < 400 K a highly anisotropic quasielastic diffuse scattering is\nobserved. Above 400 K this scattering disappears. Its main features can be\nreproduced by model of inhomogeneous lattice deformations caused by inclusions\nof a tetragonal phase into a rhombohedral or monoclinic phase. This observation\nsupports the idea that PZT at its morphotropic phase boundary is essentially\nstructurally inhomogeneous."
    },
    {
        "anchor": "Lattice gas models and Kinetic Monte Carlo simulations of epitaxial\n  growth: A brief introduction is given to Kinetic Monte Carlo (KMC) simulations of\nepitaxial crystal growth. Molecular Beam Epitaxy (MBE) serves as the prototype\nexample for growth far from equilibrium. However, many of the aspects discussed\nhear would carry over to other techniques as well. A variety of approaches to\nthe modeling and simulation of epitaxial growth has been applied. They range\nfrom the detailed quantum mechanics treatment of microscopic processes to the\ncoarse grained picture in terms of stochastic differential equations or other\ncontinuum approaches. Here, the focus is on discrete representations such as\nlattice gas and Solid-On-Solid (SOS) models. The basic ideas of the\ncorresponding KMC methods are presented. Strengths and weaknesses become\napparent in the discussion of several levels of simplification that are\npossible in this context.",
        "positive": "Effects of processing on the stability of molybdenum oxide ultra-thin\n  films: The effects of wet chemical processing conventionally employed in device\nfabrication standards are systematically studied on molybdenum oxide (MoOx)\nultra-thin films. We have combined x-ray photoelectron spectroscopy (XPS),\nangle resolved XPS and x-ray reflectivity techniques to provide deep insights\ninto the changes in composition, structure and electronic states upon treatment\nof films with different initial stoichiometry prepared by reactive sputtering.\nOur results show significant reduction effects associated with the development\nof gap states in MoOx, as well as changes in the composition, density and\nstructure of the films, systematically correlated with the initial oxidation\nstate of Mo."
    },
    {
        "anchor": "Superexchange interactions and magnetic anisotropy in MnPSe$_3$\n  monolayer: Two-dimensional van der Waals magnetic materials are of great current\ninterest for their promising applications in spintronics. In this work, using\ndensity functional theory calculations in combination with the maximally\nlocalized Wannier functions method and the magnetic anisotropy analyses, we\nstudy the electronic and magnetic properties of MnPSe$_3$ monolayer. Our\nresults show that it is a charge transfer antiferromagnetic (AF) insulator. For\nthis Mn$^{2+}$ $3d^5$ system, although it seems straightforward to explain the\nAF ground state using the direct exchange, we find that the near 90$^\\circ$\nMn-Se-Mn charge transfer type superexchange plays a dominant role in\nstabilizing the AF ground state. Moreover, our results indicate that although\nthe shape anisotropy favors an out-of-plane spin orientation, the spin-orbit\ncoupling (SOC) leads to the experimentally observed in-plane spin orientation.\nWe prove that the actual dominant contribution to the magnetic anisotropy comes\nfrom the second-order perturbation of the SOC, by analyzing its distribution\nover the reciprocal space. Using the AF exchange and anisotropy parameters\nobtained from our calculations, our Monte Carlo simulations give the N\\'eel\ntemperature $T_{\\rm N}=47$ K for MnPSe$_3$ monolayer, which agrees with the\nexperimental 40 K. Furthermore, our calculations show that under a uniaxial\ntensile (compressive) strain, N\\'eel vector would be parallel (perpendicular)\nto the strain direction, which well reproduces the recent experiments. We also\npredict that $T_{\\rm N}$ would be increased by a compressive strain.",
        "positive": "Crystallization and Vitrification Kinetics by Design: The Role of\n  Chemical Bonding: Controlling a state of material between its crystalline and glassy phase has\nfostered many real-world applications. Nevertheless, design rules for\ncrystallization and vitrification kinetics still lack predictive power. Here,\nwe identify stoichiometry trends for these processes in phase change materials,\ni.e. along the GeTe-GeSe, GeTe-SnTe, and GeTe-Sb2Te3 pseudo-binary lines\nemploying a pump-probe laser setup and calorimetry. We discover a clear\nstoichiometry dependence of crystallization speed along a line connecting\nregions characterized by two fundamental bonding types, metallic and covalent\nbonding. Increasing covalency slows down crystallization by six orders of\nmagnitude and promotes vitrification. The stoichiometry dependence is\ncorrelated with material properties, such as the optical properties of the\ncrystalline phase and a bond indicator, the number of electrons shared between\nadjacent atoms. A quantum-chemical map explains these trends and provides a\nblueprint to design crystallization kinetics."
    },
    {
        "anchor": "Large orbital magnetic moment in VI3: The existence of the V3+ ion orbital moment is the open issue of the nature\nof magnetism in the van der Waals ferromagnet VI3. The huge magnetocrystalline\nanisotropy in conjunction with the significantly reduced ordered magnetic\nmoment compared to the spin-only value provides strong but indirect evidence of\na significant V orbital moment. We used the unique capability of X-ray magnetic\ncircular dichroism to determine the orbital component of the total magnetic\nmoment and provide for the first time a direct proof of an exceptionally\nsizable orbital moment of the V3+ ion in VI3. Our ligand field multiplet\nsimulations of the XMCD spectra in synergy with the results of DFT calculations\nagree with the existence of two V sites with different orbital occupations and\ntherefore different OM magnitudes in the ground state.",
        "positive": "Interplay Between Stacking Order and In-plane Strain on the Electrical\n  Properties of Bilayer Antimonene: In this work, the electrical properties of bilayer Antimonene with different\nstacking orders are studied. Density functional theory with van der Waals (vdW)\ncorrection is used to investigate the electrical performances. Two\nconfigurations demonstrate considerable bandgaps, whereas, the bandgaps are\nclose to zero for other structures. The in-plane biaxial strain is applied to\nmodify the electrical properties. The bandgap reaches a maximum at a specific\nstrain level and then closes at more enormous compressive and tensile strains.\nThe energy of three valleys ($\\Gamma$, Q, and K) in the conduction band are\nexplored with the strain. The conduction band minimum switches between these\nvalleys with the strain. Two bands also contribute to the valence band maximum,\nand the energy of these two bands for various strains is investigated. Finally,\nthe effective mass for the valleys of the conduction band and the valence band\nare obtained. The effective mass at $\\Gamma$-valley demonstrates the lowest\neffective mass."
    },
    {
        "anchor": "CTRAMER: An open source software package for correlating interfacial\n  charge transfer rate constants with donor acceptor geometries in organic\n  photovoltaic materials: In this paper we present CTRAMER (Charge Transfer RAtes from Molecular\ndynamics, Electronic structure, and Rate theory), an open source software\npackage for calculating interfacial charge transfer (CT) rate constants in\norganic photovoltaic (OPV) materials based on ab initio calculations and\nmolecular dynamics simulations. The software is based on identifying\nrepresentative donor acceptor geometries within interfacial structures obtained\nfrom molecular dynamics simulation of donor acceptor blends and calculating the\ncorresponding Fermi s golden rule CT rate constants within the framework of the\nlinearized semiclassical approximation. While the methods used are well\nestablished, the integration of these state of the art ideas from different\ndisciplines to study photoinduced CT between excited states and explicit\nenvironment, in our opinion, makes this package unique and innovative. The\nsoftware also provides tools for plotting other observables of interest. After\noutlining the features and implementation details, usage and performance of the\nsoftware are demonstrated with results from an example OPV system.",
        "positive": "Unravelling a Zigzag Pathway for Hot-Carrier Collection at\n  CH3NH3PbI3/Graphene Interfaces: The capture of photoexcited deep-band hot carriers, excited by photons with\nenergies far above the bandgap, is of significant importance for photovoltaic\nand photoelectronic applications since it is directly related to the quantum\nefficiency of photon-to-electron conversion. By employing time-resolved\nphotoluminescence and state-of-the-art time-domain density functional theory,\nwe reveal that photoexcited hot carriers in organic-inorganic hybrid\nperovskites prefer a zigzag interfacial charge-transfer pathway, i.e., the hot\ncarriers transfer back and forth between CH3NH3PbI3 and graphene, before they\nreach a charge separated state. Driven by quantum coherence and interlayer\nvibrational modes, this pathway at the semiconductor-graphene interface takes\nabout 400 femtoseconds, much faster than the relaxation process within\nCH3NH3PbI3 (in several picoseconds). We further demonstrate that the transfer\nrate of the pathway can be further enhanced by interfacial defects. Our work\nprovides a new insight for the fundamental understanding and precise\nmanipulation of hot-carrier dynamics at the complex semiconductor-graphene\ninterfaces, paving the way for highly efficient photovoltaic and photoelectric\ndevice optimization."
    },
    {
        "anchor": "Evaluation of microstructure and mechanical property variations in\n  AlxCoCrFeNi high entropy alloys produced by a high-throughput laser\n  deposition method: Twenty-one distinct AlxCoCrFeNi alloys were rapidly prepared by laser\nalloying an equiatomic CoCrFeNi substrate with Al powder to create an alloy\nlibrary ranging x=0.15-1.32. Variations in crystal structure, microstructure\nand mechanical properties were investigated using X-ray diffraction, scanning\nelectron microscopy, scanning transmission electron microscopy and\nnanoindentation. With increasing Al content, the crystal structure transitioned\nfrom a disordered FCC to a mixture of disordered BCC and ordered B2 structures.\nWhile the onset of BCC/B2 formation was consistent with previously reported\ncast alloys, the FCC structure was observed at larger Al contents in the laser\nprocessed materials, resulting in a wider two phase regime. The FCC phase was\nprimarily confined to the BCC/B2 grain boundaries at these high Al contents.\nThe nanoindentation modulus and hardness of the FCC phase increased with Al\ncontent, while the properties of the BCC/B2 structure were insensitive to\ncomposition. The structure and mechanical properties of the laser-processed\nalloys were surprisingly consistent with reported results for cast alloys,\ndemonstrating the feasibility of applying this high-throughput methodology to\nmulticomponent alloy design.",
        "positive": "Local Crystal Misorientation Influences Non-Radiative Recombination: We use ultrasensitive electron backscatter diffraction (EBSD) to map the\nlocal crystal orientations, grains, and grain boundaries in CH3NH3PbI3 (MAPI)\nperovskite thin films. Although the true grain structure is broadly consistent\nwith the morphology visible in scanning electron microscopy (SEM), the inverse\npole figure maps taken with EBSD reveal grain structure and internal\nmisorientation that is otherwise hidden. Local crystal misorientation is\nconsistent with the presence of local strain which varies from one grain to the\nnext. We acquire co-aligned confocal optical photoluminescence (PL) microscopy\nimages on the same MAPI samples used for EBSD. We correlate optical and EBSD\ndata, showing that PL is anticorrelated with the local grain orientation\nspread, suggesting that grains with higher degrees of crystalline orientational\nheterogeneity (local strain) exhibit more non-radiative recombination. We find\nthat larger grains tend to have larger grain orientation spread, consistent\nwith higher degrees of strain and non-radiative recombination."
    },
    {
        "anchor": "As-based ternary Janus monolayers for efficient thermoelectric and\n  photocatalytic applications: Highly efficient and sustainable resources of energy are of great demand\ntoday to combat with environmental pollution and the energy crisis. In this\nwork, we have examined the novel 2D Janus AsTeX (X = Cl, Br and I) monolayers\nusing first-principles calculations and explore their potential energy\nconversion applications. We have demonstrated the thermal, energetic, dynamic\nand mechanical stability of AsTeX (X = Cl, Br, and I) monolayers. Janus AsTeX\n(X = Cl, Br and I) monolayers are indirect bandgap semiconductors with high\ncarrier mobilities and excellent visible light optical absorption. Our findings\ndemonstrate that the Janus AsTeCl and AsTeBr monolayers exhibits low lattice\nthermal conductivity and excellent electronic transport properties obtained\nusing semi-classical Boltzmann transport theory including various scattering\nmechanism. Additionally, the redox potential of water is adequately engulfed by\nthe band alignments of the AsTeCl and AsTeBr monolayers. The water splitting\nprocess under illumination can proceeds spontaneously on Janus AsTeBr\nmonolayer, while a minimal low external potential (0.26-0.29 eV) is required to\ntrigger water splitting process on Janus AsTeCl monolayer. A more than 10% STH\nefficiency of these monolayers indicate their potential practical applications\nin the commercial production of hydrogen. Thus, our study demonstrates that\nthese monolayers can show potential applications in energy conversion fields.",
        "positive": "Magnetic transition and spin-polarized two-dimensional electron gas\n  controlled by polarization switching in strained CaMnO$_3$/BaTiO$_3$ slabs: $Ab$ $initio$ calculations show the presence of a strong magnetoelectric\ninterfacial coupling in CaMnO$_3$ ultra-thin film grown on a strained BaTiO$_3$\nferroelectric film. This heterostructure presents a polarization driven\nmagnetic transition from a G-type to an A-type antiferromagnetic structure.\nTogether with this magnetic transition we find a metallic behaviour at the\ninterface between these two insulators, where the charge character of the\ncarriers can be tuned from electrons to holes by switching the electric\npolarization direction of the FE film. Besides, the electron gas is\nspin-polarized while the hole-gas is not."
    },
    {
        "anchor": "Three-Dimensional Interface Roughness in Layered Semiconductor\n  Structures and Its Effects on Intersubband Transitions: A general model for treating the effects of three dimensional interface\nroughness (IFR) in layered semiconductor structures has been derived and\nexperimentally verified. Configurational averaging of the IFR potential\nproduces an effective grading potential in the out-of-plane direction, greatly\naltering the energy spectrum of the structures. IFR scattering self-energy is\nalso derived for the general case; when IFR is strong, its scattering effect is\nshown to dominate over phonon interaction and impurity scattering. When applied\nto intersubband transitions, the theoretical predictions explain the\nexperimental observation of the anomalous energy shift and unusual broadening\nof the ISB transitions in III-Nitride thin-layered superlattices.",
        "positive": "Magnetically-triggered Nanocomposite Membranes: a Versatile Platform for\n  Triggered Drug Release: Drug delivery devices based on nanocomposite membranes containing\nthermoresponsive nanogels and superparamagnetic nanoparticles have been\ndemonstrated to provide reversible, on-off drug release upon application (and\nremoval) of an oscillating magnetic field. The dose of drug delivered can be\ntuned by engineering the phase transition temperature of the nanogel, the\nloading of nanogels in the membrane, and the membrane thickness, allowing for\nthe delivery of drugs over several orders of magnitude of release rates. The\nzero-order kinetics of drug release through the membranes permit drug doses\nfrom a specific device to be tuned according to the duration of the magnetic\nfield. Drugs over a broad range of molecular weights (500-40,000 Da) can be\ndelivered by the same membrane device. Membrane-to-membrane and cycle-to-cycle\nreproducibility is demonstrated, suggesting the general utility of these\nmembranes for drug delivery."
    },
    {
        "anchor": "Effect of vacancy defects on geometrically frustrated magnets: Quenched disorder may prevent the formation of the widely sought\nquantum-spin-liquid states (QSLs) or mask their signatures by inducing a\nspin-glass state, which is why considerable experimental efforts are directed\nat purifying materials that may host QSLs. However, in geometrically frustrated\n(GF) magnets, the largest class of materials in which QSLs are sought, the\nglass-transition temperature $T_g$ grows with decreasing the density of vacancy\ndefects, accompanied by a simultaneous growth of the magnetic susceptibility.\nIn this paper, we develop a phenomenological theory of glass transitions and\nmagnetic susceptibility in 3D geometrically frustrated (GF) magnetic materials.\nWe consider a model of a GF magnet in which the glass transition occurs in the\nabsence of vacancies, e.g., due to other types of quenched disorder. We show\nthat disorder that creates weak local perturbations, e.g. weak random strain,\nleads to the growth of the transition temperature $T_g$. By contrast, vacancies\nreduce $T_g$ for small vacancy concentrations. Another consequence of the\npresence of vacancies is the creation of quasispins, effective magnetic moments\nlocalised near the vacancies, that contribute to the magnetic susceptibility of\nthe system together with the bulk spins. We show that increasing the vacancy\ndensity leads to an increase of the total magnetic susceptibility.",
        "positive": "Inverse Spin-Galvanic Effect in a Topological-Insulator/Ferromagnet\n  Interface: When a ferromagnet is deposited on the surface of a topological insulator the\ntopologically protected surface state develops a gap and becomes a\n2-dimensional quantum Hall liquid. We demonstrate that the Hall current in such\na liquid, induced by an external electric field, can have a large effect on the\nmagnetization dynamics of the ferromagnet by changing the effective anisotropy\nfield. This change is dissipationless and may be substantial even in weakly\nspin-orbit coupled ferromagnets. We study the possibility of dissipationless\ncurrent-induced magnetization reversal in monolayer-thin, insulating\nferromagnets with a soft perpendicular anisotropy and discuss possible\napplications of this effect."
    },
    {
        "anchor": "Phonon anharmonic frequency shift induced by four-phonon scattering\n  calculated from first principles: Phonon energies at finite temperatures shift away from their harmonic values\ndue to anharmonicity. In this paper, we have realized the rigorous calculation\nof phonon energy shifts of silicon by three and four-phonon scattering from\nfirst principles. The anharmonic fourth-order force constants are calculated by\nconsidering up to the fifth nearest neighbors. The results agree reasonably\nwell with available data from inelastic neutron scattering throughout the\nBrillouin zone. Surprisingly, the frequency shifts of optical phonon modes near\nthe $\\Gamma$ point are sensitive to the cutoff radius of the fourth-order force\nconstants, in contrast to the four-phonon scattering rates, which nearly\nsaturate when considering the second nearest neighbors. We have also compared\nthe results with ab initio molecular dynamics simulations and found that the\nhigher order of anharmonicity is important for optical phonons. Our work\nprovides critical insight into the anharmonic phonon frequency shift and will\nhave significant impact on the thermal and optical applications.",
        "positive": "On the Reactivity of Hydrogen-Helium and Hydrogen-Nitrogen at High\n  Pressures: Through a series of Raman spectroscopy studies, we investigate the behaviour\nof hydrogen-helium and hydrogen-nitrogen mixtures at high pressure across wide\nranging concentrations. We find that there is no evidence of chemical\nassociation, miscibility, nor any demixing of hydrogen and helium in the solid\nstate up to pressures of 250 GPa at 300 K. In contrast, we observe the\nformation of concentration-dependent N$_2$-H$_2$ van der Waals solids, which\nreact to form N-H bonded compounds above 50 GPa. Through this combined study,\nwe can demonstrate that the recently claimed chemical association of H$_2$-He\ncan be attributed to significant N$_2$ contamination and subsequent formation\nof N$_2$-H$_2$ compounds."
    },
    {
        "anchor": "What Happens at Surfaces and Grain Boundaries of Halide Perovskites:\n  Insights from Reactive Molecular Dynamics Simulations of CsPbI$_{3}$: The commercialization of perovskite solar cells is hindered by the poor\nlong-term stability of the metal halide perovskite (MHP) light absorbing layer.\nSolution processing, the common fabrication method for MHPs, produces\npolycrystalline films with a wide variety of defects, such as point defects,\nsurfaces, and grain boundaries. Although the optoelectronic effects of such\ndefects have been widely studied, the evaluation of their impact on the\nlong-term stability remains challenging. In particular, an understanding of the\ndynamics of degradation reactions at the atomistic scale is lacking. In this\nwork, using reactive force field (ReaxFF) molecular dynamics simulations, we\ninvestigate the effects of defects, in the forms of surfaces, surface defects\nand grain boundaries, on the stability of the inorganic halide perovskite\nCsPbI$_{3}$. Our simulations establish a stability trend for a variety of\nsurfaces, which correlates well with the occurrence of these surfaces in\nexperiments. We find that a perovskite surface degrades by progressively\nchanging the local geometry of PbI$_{\\mathrm{x}}$ octahedra from corner- to\nedge- to face-sharing. Importantly, we find that Pb dangling bonds and the lack\nof steric hindrance of I species are two crucial factors that induce\ndegradation reactions. Finally, we show that the stability of these surfaces\ncan be modulated by adjusting their atomistic details, either by creating\nadditional point defects or merging them to form grain boundaries. While in\ngeneral additional defects, particularly when clustered, have a negative impact\non the material stability, some grain boundaries have a stabilizing effect,\nprimarily because of the additional steric hindrance.",
        "positive": "A Universal Graph Deep Learning Interatomic Potential for the Periodic\n  Table: Interatomic potentials (IAPs), which describe the potential energy surface of\natoms, are a fundamental input for atomistic simulations. However, existing\nIAPs are either fitted to narrow chemistries or too inaccurate for general\napplications. Here, we report a universal IAP for materials based on graph\nneural networks with three-body interactions (M3GNet). The M3GNet IAP was\ntrained on the massive database of structural relaxations performed by the\nMaterials Project over the past 10 years and has broad applications in\nstructural relaxation, dynamic simulations and property prediction of materials\nacross diverse chemical spaces. About 1.8 million materials were identified\nfrom a screening of 31 million hypothetical crystal structures to be\npotentially stable against existing Materials Project crystals based on M3GNet\nenergies. Of the top 2000 materials with the lowest energies above hull, 1578\nwere verified to be stable using DFT calculations. These results demonstrate a\nmachine learning-accelerated pathway to the discovery of synthesizable\nmaterials with exceptional properties."
    },
    {
        "anchor": "Interlayer magnetic interactions in $\u03c0/3$-twisted bilayer CrI$_3$: The interlayer magnetic interaction in bilayer CrI$_3$ plays a crucial role\nfor its device applications. In this work, we studied the interlayer magnetic\ninteraction in $\\pi/3$-twisted bilayer CrI$_3$ using first-principles\ncalculations. Our calculations show that the interlayer coupling can be\nferromagnetic or antiferromagnetic depending crucially on lateral shift. The\nstrongest antiferromagnetic interlayer interaction appears in the\n$\\bar{A}A$-stacking. The magnetic force theory calculations demonstrate that\nsuch an antiferromagnetic interaction is dominanted by the $e_g$-$e_g$ channel.\nParticularly, the interlayer antiferromagnetic interaction is very sensitive to\nexternal pressure. This highly tunable interlayer interaction makes\n$\\pi/3$-twisted bilayer CrI$_3$ a potential building block for magnetic field\neffect transistors and pressure sensors.",
        "positive": "First-Principles Study of Localised and Delocalised Electronic States in\n  Crystallographic Shear Phases of Niobium Oxide: Crystallographic shear phases of niobium oxide form an interesting family of\ncompounds that have received attention both for their unusual electronic and\nmagnetic properties, as well as their performance as intercalation electrode\nmaterials for lithium-ion batteries. Here, we present a first-principles\ndensity-functional theory study of the electronic structure and magnetism of\nH-Nb$_2$O$_5$, Nb$_{25}$O$_{62}$, Nb$_{47}$O$_{116}$, Nb$_{22}$O$_{54}$, and\nNb$_{12}$O$_{29}$. These compounds feature blocks of niobium-oxygen octahedra\nas structural units, and we show that this block structure leads to a\ncoexistence of flat and dispersive energy bands, corresponding to localised and\ndelocalised electronic states. Electrons localise in orbitals spanning multiple\nniobium sites in the plane of the blocks. Localised and delocalised electronic\nstates are both effectively one-dimensional and are partitioned between\ndifferent types of niobium sites. Flat bands associated with localised\nelectrons are present even at the GGA level, but a correct description of the\nlocalisation requires the use of GGA+U or hybrid functionals. We discuss the\nexperimentally observed electrical and magnetic properties of niobium suboxides\nin light of our results, and argue that their behaviour is similar to that of\n$n$-doped semiconductors, but with a limited capacity for localised electrons.\nWhen a threshold of one electron per block is exceeded, metallic electrons are\nadded to existing localised electrons. We propose that this behaviour of shear\nphases is general for any type of $n$-doping, and should transfer to doping by\nalkali metal (lithium) ions during operation of niobium oxide-based battery\nelectrodes. Future directions for theory and experiment on mixed-metal shear\nphases are suggested."
    },
    {
        "anchor": "Van der Waals forces and electron-electron interactions in two strained\n  graphene layers: We evaluate the van der Waals (vdW) interaction energy at zero temperature\nbetween two undoped strained graphene layers separated by a finite distance. We\nconsider the following three models for the anisotropic case: (a) where one of\nthe two layers is uniaxially strained, (b) the two layers are strained in the\nsame direction, and (c) one of the layers is strained in the perpendicular\ndirection with respect to the other. We find that for all three models and\ngiven value of the electron-electron interaction coupling, the vdW interaction\nenergy increases with increasing anisotropy. The effect is most striking for\nthe case when both layers are strained in the same direction where we observe\nup to an order of magnitude increase in the strained relative to the unstrained\ncase. We also investigate the effect of electron electron interaction\nrenormalization in the region of large separation between the strained graphene\nlayers. We find that the many-body renormalization contributions to the\ncorrelation energy are non negligible and the vdW interaction energy decreases\nas a function of increasing distance between the layers due to renormalization\nof the Fermi velocity, the anisotropy, and the effective interaction. Our\nanalysis can be useful in designing novel graphene-based vdW heterostructures\nwhich, in recent times, has seen an upsurge in research activity.",
        "positive": "A python tool to determine the thickness of the hydrate layer around\n  clinker grains using SEM-BSE images: To accurately simulate the hydration process of cementitious materials,\nunderstanding the growth rate of C-S-H layers around clinker grains is crucial.\nNonetheless, the thickness of the hydrate layer shows substantial variation\naround individual grains, depending on their surrounding. Consequently, it is\nnot feasible to measure hydrate layers manually in a reliable and reproducible\nmanner. To address this challenge, a software has been developed to\nstatistically determine the C-S-H thickness, requiring minimal manual\ninterventions for thresholding and for setting limits like particle size or\ncircularity.\n  This study presents a tool, which automatically identifies suitable clinker\ngrains and and perform statistical measurements of their hydrate layer up to a\nspecimen age of 28 days. The findings reveal a significant increase in the\nC-S-H layer, starting from 0.45 micrometer after 1 day and reaching 3.04\nmicrometer after 28 days. However, for older specimens, the measurement of the\nC-S-H layer was not feasible due to limited pore space and clinker grains."
    },
    {
        "anchor": "Composition, structure, and stability of the rutile TiO_2(110) surface:\n  oxygen depletion, hydroxylation, hydrogen migration and water adsorption: A comprehensive phase diagram of lowest-energy structures and compositions of\nthe rutile TiO_2(110) surface in equilibrium with a surrounding gas phase at\nfinite temperatures and pressures has been determined using density functional\ntheory in combination with a thermodynamic formalism. The exchange of oxygen,\nhydrogen, and water molecules with the gas phase is considered. Particular\nattention is given to the convergence of all calculations with respect to\nlateral system size and slab thickness. In addition, the reliability of\nsemilocal density functionals to describing the energetics of the reduced\nsurfaces is critically evaluated. For ambient conditions the surface is found\nto be fully covered by molecularly adsorbed water. At low coverages, in the\nlimit of single, isolated water molecules, molecular and dissociative\nadsorption become energetically degenerate. Oxygen vacancies form in strongly\nreducing, oxygen-poor environments. However, already at slightly more moderate\nconditions it is shown that removing full TiO_2 units from the surface is\nthermodynamically preferred. In agreement with recent experimental observations\nit is furthermore confirmed that even under extremely hydrogen-rich\nenvironments the surface cannot be fully hydroxylated, but only a maximum\ncoverage with hydrogen of about 0.6-0.7 monolayer can be reached. Finally,\ncalculations of migration paths strongly suggest that hydrogen prefers to\ndiffuse into the bulk over desorbing from the surface into the gas phase.",
        "positive": "The Ultrafast Optical Response of the Amorphous and Crystalline States\n  of the Phase Change Material Ge$_2$Sb$_2$Te$_5$: We examine the ultrafast optical response of the crystalline and amorphous\nphases of the phase change material Ge$_2$Sb$_2$Te$_5$ below the phase\ntransformation threshold. Simultaneous measurement of the transmissivity and\nreflectivity of thin film samples yields the time-dependent evolution of the\ndielectric function for both phases. We then identify how lattice motion and\nelectronic excitation manifest in the dielectric response. The dielectric\nresponse of both phases is large but markedly different. At 800 nm, the changes\nin amorphous GST are well described by the Drude response of the generated\nphoto-carriers, whereas the crystalline phase is better described by the\ndepopulation of resonant bonds. We find that the generated coherent phonons\nhave a greater influence in the amorphous phase than the crystalline phase.\nFurthermore, coherent phonons do not influence resonant bonding. For fluences\nup to 50% of the transformation threshold, the structure does not exhibit bond\nsoftening in either phase, enabling large changes of the optical properties\nwithout structural modification."
    },
    {
        "anchor": "Conversion of Heat into Charge Current by the Spin Wave Anomalous Nernst\n  Effect: A novel process of spin conversion from a temperature gradient to a\ntransverse voltage is addressed in this paper, viz. the anomalous Nernst effect\n(ANE) in a ferromagnetic metal. We report that an additional voltage is\nsuperposed on the conventional anomalous Nernst voltage in FePt crystalline\nthin films. The dynamics of the local magnetization is modulated by the heat\ncurrent and excites spin waves. These generate a conduction electron spin\ncurrent via s-d coupling, which flows along the temperature gradient, and the\nspin current is converted to a Nernst voltage by the inverse spin Hall effect.",
        "positive": "Discontinuous Shear Thickening (DST) transition with spherical iron\n  particles coated by adsorbed brush polymer: In this work we explore the rheology of very concentrated (0.55<$\\Phi$<0.67)\nsuspensions of carbonyl iron (CI) particles coated by a small polymer. A strong\nDST is observed in a large range of volume fraction presenting some\nspecificities relatively to other systems. In particular, in a given range of\nvolume fraction, the DST transition appears suddenly without being preceded by\nshear thickening. The presence of a frictional network of particles is\nconfirmed by a simultaneous measurement of the electric resistance of the\nsuspension and of the rheological curve. Using the Wyart-Cates model we show\nthat, increasing the volume fraction, the fraction of frictional contacts grows\nmore and more quickly with the stress that disagrees with the prediction of\ncomputer simulations. The same kind of behavior is observed in the presence of\na magnetic field with, in addition, a very strong increase of the viscosity\nwith the magnetic field before the transition. We interpret this behavior by\nthe interpenetration of the polymer layer under the effect of the shear\nstress-and of the magnetic stress-followed by the expulsion of the polymer out\nof the surfaces. Besides we point that, above the DST transition, we do not\nobserve a jamming in the range of volume fraction whereas it is predicted by\nthe W-C model. Based on the fact that in the absence of shear flow, the polymer\nshould come back to the surface and destroy the frictional contacts we can\npredict an asymptotic non-zero shear rate and reproduce the experimental\nbehavior."
    },
    {
        "anchor": "Preserving the Q-Factors of ZnO Nanoresonators via Polar Surface\n  Reconstruction: We perform molecular dynamics simulations to investigate the effect of polar\nsurfaces on the quality (Q)-factors of zinc oxide (ZnO) nanowire-based\nnanoresonators. We find that the Q-factors in ZnO nanoresonators with free\npolar (0001) surfaces is about one order of magnitude higher than in\nnanoresonators that have been stabilized with reduced charges on the polar\n(0001) surfaces. From normal mode analysis, we show that the higher Q-factor is\ndue to a shell-like reconstruction that occurs for the free polar surfaces.\nThis shell-like reconstruction suppresses twisting motion in the nanowires such\nthat the mixing of other modes with the resonant mode of oscillation is\nminimized, and leads to substantially higher Q-factors in the ZnO\nnanoresonators with free polar surfaces.",
        "positive": "Thermodynamical approach to nanodomain tailoring in thin\n  ferroelectric-semiconductor films: We propose the thermodynamical theory of nanodomain tailoring with the help\nof atomic force microscope electric field in thin ferroelectric-semiconductor\nfilms. We modified the existing thermodynamical models of domain formation\nallowing for the Debye screening, recharging of sluggish surface charge layers\ncaused by emission current between the tip apex and sample surface.For the\nfirst time we calculated the realistic sizes of nanodomains recorded in BaTiO3,\nPbZrxTi1-xO3 and LiTaO3 ferroelectric-semiconductor thin films in contrast to\nthe over-estimated ones obtained in the evolved approaches. We have shown that\nthe depolarization field energy of the domain butt, Debye screening effects and\nfield emission at high voltages lead to the essential decrease of the\nequilibrium domain sizes. For the first time we obtained, that the domain\nradius does not decrease continuously with applied voltage decrease: the domain\nappears with non-zero radius at definite critical voltage applied to the tip.\nThis result completely agrees with experimentally observed threshold domain\nrecording in PbZrxTi1-xO3 and LiTaO3 thin films. Such threshold domain\nformation is similar to the first order phase transition. We hope, that our\nresults will help one to determine the necessary recording conditions and\nappropriate ferroelectric medium in order to obtain the stable domains with\nminimum lateral size in a wide range of applied voltages."
    },
    {
        "anchor": "Giant negative electrostriction and dielectric tunability in a van der\n  Waals layered ferroelectric: The interest in ferroelectric van der Waals crystals arises from the\npotential to realize ultrathin ferroic systems owing to the reduced surface\nenergy of these materials and the layered structure that allows for\nexfoliation. Here, we quantitatively unravel giant negative electrostriction of\nvan der Waals layered copper indium thiophosphate (CIPS), which exhibits an\nelectrostrictive coefficient Q33 as high as -3.2 m4/C2 and a resulting bulk\npiezoelectric coefficient d33 up to -85 pm/V. As a result, the\nelectromechanical response of CIPS is comparable in magnitude to established\nperovskite ferroelectrics despite possessing a much smaller spontaneous\npolarization of only a few uC/cm2. In the paraelectric state, readily\naccessible owing to low transition temperatures, CIPS exhibits large dielectric\ntunability, similar to widely-used barium strontium titanate, and as a result\nboth giant and continuously tunable electromechanical response. The persistence\nof electrostrictive and tunable responses in the paraelectric state indicates\nthat even few layer films or nanoparticles will sustain significant\nelectromechanical functionality, offsetting the inevitable suppression of\nferroelectric properties in the nanoscale limit. These findings can likely be\nextended to other ferroelectric transition metal thiophosphates and (quasi-)\ntwo-dimensional materials and might facilitate the quest towards novel\nultrathin functional devices incorporating electromechanical response.",
        "positive": "Combined treatment of phonon scattering by electrons and point defects\n  explains the thermal conductivity reduction in highly-doped Si: The mechanisms causing the reduction in lattice thermal conductivity in\nhighly P- and B-doped Si are looked into in detail. Scattering rates of phonons\nby point defects, as well as by electrons, are calculated from first\nprinciples. Lattice thermal conductivities are calculated considering these\nscattering mechanisms both individually and together. It is found that at low\ncarrier concentrations and temperatures phonon scattering by electrons is\ndominant and can reproduce the experimental thermal conductivity reduction.\nHowever, at higher doping concentrations the scattering rates of phonons by\npoint defects dominate the ones by electrons except for the lowest phonon\nfrequencies. Consequently, phonon scattering by point defects contributes\nsubstantially to the thermal conductivity reduction in Si at defect\nconcentrations above $10^{19}$ cm$^{-3}$ even at room temperature. Only when,\nphonon scattering by both point defects and electrons are taken into account,\nexcellent agreement is obtained with the experimental values at all\ntemperatures."
    },
    {
        "anchor": "Thermal conductivity of hemp concretes: Variation with formulation,\n  density and water content: This study investigates the effect of formulation, density and water content\non the thermal conductivity of hemp concretes. The investigations are based on\nexperimental measurements and on self-consistent scheme modelling. The thermal\nconductivity of studied materials ranges from 90 to 160 mW/(m.K) at (23 degrees\nC; 50%HR). The impact of density on thermal conductivity is much more important\nthan the impact of moisture content. It is shown that the thermal conductivity\nincreases by about 54 % when the density increases by 2/3 while it increases by\nless than 15 % to 20 % from dry state to 90%RH.",
        "positive": "Thermally-Induced Structural Evolution of Silicon- and Oxygen-Containing\n  Hydrogenated Amorphous Carbon: The thermally-induced structural evolution of silicon- and oxygen-containing\nhydrogenated amorphous carbon (a-C:H:Si:O) was investigated by X-ray\nphotoelectron and absorption spectroscopy, as well as molecular dynamics (MD)\nsimulations. The spectroscopic results indicate that the introduction of Si and\nO in hydrogenated amorphous carbon (a-C:H) increases the activation energy for\nthe conversion of sp3- to sp2-bonded C. MD simulations indicate that the higher\nthermal stability of a-C:H:Si:O compared to a-C:H derives from the lower\nfraction of strained C-C sp3 bonds in a-C:H:Si:O."
    },
    {
        "anchor": "Trends in Atomic Adsorption on Titanium Carbide and Nitride: Extensive density-functional calculations on atomic chemisorption of H, B, C,\nN, O, F, Al, Si, P, S, and Cl on the polar TiC(111) and TiN(111) yield similar\nadsorption trends for the two surfaces: (i) pyramid-like adsorption-energy\ntrends along the adatom periods; (ii) strongest adsorption for O, C, N, S, and\nF; (iii) large adsorption variety; (iv) record-high adsorption energy for O\n(8.4-8.8 eV). However, a stronger adsorption on TiN is found for elements on\nthe left of the periodic table and on TiC for elements on the right. The\nresults support that a concerted-coupling model, proposed for chemisorption on\nTiC, applies also to TiN.",
        "positive": "Gas Adsorption and Diffusion Behaviors in Interfacial Systems Composed\n  of a Polymer of Intrinsic Microporosity and Amorphous Silica: A Molecular\n  Simulation Study: We investigate the adsorption and diffusion behaviors of CO2, CH4, and N2 in\ninterfacial systems composed of a polymer of intrinsic microporosity (PIM-1)\nand amorphous silica using grand canonical Monte Carlo (GCMC) and molecular\ndynamics (MD) simulations. We build model systems of mixed matrix membranes\n(MMMs) with PIM-1 chains sandwiched between silica surfaces. Gas adsorption\nanalysis using GCMC simulations shows that gas molecules are preferentially\nadsorbed in microcavities distributed near silica surfaces, resulting in an\nincrease in the solubility coefficients of CO2, CH4, and N2 compared to bulk\nPIM-1. In contrast, diffusion coefficients obtained from MD simulations and\nthen calibrated using the dual-mode sorption model show different tendencies\ndepending on gas species: CO2 diffusivity decreases in MMMs compared to PIM-1,\nwhereas CH4 and N2 diffusivities increase. These differences are attributed to\ncompeting effects of silica surfaces: the emergence of larger pores as a result\nof chain packing disruption, which enhances gas diffusion, and a\nquadrupole-dipole interaction between gas molecules and silica surface hydroxyl\ngroups, which retards gas diffusion. The former has a greater impact on CH4 and\nN2 diffusivities, whereas the latter has a greater impact on CO2 diffusivity\ndue to the strong quadrupole-dipole interaction between CO2 and surface\nhydroxyls. These findings add to our understanding of gas adsorption and\ndiffusion behaviors in the vicinity of PIM-1/silica interfaces, which are\nunobtainable in experimental studies."
    },
    {
        "anchor": "Spin Pumping of an Easy-Plane Antiferromagnet Enhanced by\n  Dzyaloshinskii-Moriya Interaction: Recently, antiferromagnets have received revived interest due to their\nsignificant potential for developing next-generation ultrafast magnetic\nstorage. Here we report dc spin pumping by the acoustic resonant mode in a\ncanted easy-plane antiferromagnet {\\alpha}-Fe2O3 enabled by the\nDzyaloshinskii-Moriya interaction. Systematic angle and frequency dependent\nmeasurements demonstrate that the observed spin pumping signals arise from\nresonance-induced spin injection and inverse spin Hall effect in\n{\\alpha}-Fe2O3/metal heterostructures, mimicking the behavior of spin pumping\nin conventional ferromagnet/nonmagnet systems. The pure spin current nature is\nfurther corroborated by reversal of the polarity of spin pumping signals when\nthe spin detector is switched from platinum to tungsten which has an opposite\nsign of the spin Hall angle. Our results highlight the potential opportunities\noffered by the low-frequency acoustic resonant mode in canted easy-plane\nantiferromagnets for developing next-generation, functional spintronic devices.",
        "positive": "Effect of the shape anisotropy on the magnetic configuration of\n  (Ga,Mn)As and its evolution with temperature: We study the effect of the shape anisotropy on the magnetic domain\nconfigurations of a ferromagnetic semiconductor (Ga,Mn)As/GaAs(001) epitaxial\nwire as a function of temperature. Using magnetoresistance measurements, we\ndeduce the magnetic configurations and estimate the relative strength of the\nshape anisotropy compared with the intrinsic anisotropies. Since the intrinsic\nanisotropy is found to show a stronger temperature dependence than the shape\nanisotropy, the effect of the shape anisotropy on the magnetic domain\nconfiguration is relatively enhanced with increasing temperature. This\ninformation about the shape anisotropy provides a practical means of designing\nnanostructured spin electronic devices using (Ga,Mn)As."
    },
    {
        "anchor": "Extraction of the Anomalous Nernst Effect in the Electric Measurement of\n  the Spin Orbit Torque: Spin orbit torque has been intensively investigated because of its high\nenergy efficiency in manipulating a magnetization. Although various methods for\nmeasuring the spin orbit torque have been developed so far, the measurement\nresults often show inconsistency among the methods, implying that an\nelectromotive force, such as Nernst effect, irrelevant to the spin orbit torque\nmay affect the measurement results as an artifact. In this letter, we developed\na unique method to distinguish the spin orbit torque and the anomalous Nernst\neffect. The measurement results show that the spin orbit torque can be\nunderestimated up to 50% under the influence of the anomalous Nernst effect.",
        "positive": "Suppression of the ferromagnetic order in the Heusler alloy Ni50Mn35In15\n  by hydrostatic pressure: We report the effect of hydrostatic pressure on the magnetic and structural\nproperties of the shape-memory Heusler alloy Ni50Mn35In15. Magnetization and\nx-ray diffraction experiments were performed at hydrostatic pressures up to 5\nGPa using diamond anvil cells. Pressure stabilizes the martensitic phase,\nshifting the martensitic transition to higher temperatures and suppresses the\nferromagnetic austenitic phase. Above ~3 GPa, where the martensitic-transition\ntemperature approaches the Curie temperature in the austenite, the\nmagnetization shows no indication of ferromagnetic ordering anymore. We further\nfind an extremely large temperatureregion with a mixture of martensite and\naustenite phases, which directly relates to the magnetic properties."
    },
    {
        "anchor": "Study of the composition dependence of the ionic conductivity of\n  LiH_{x}D_{1-x} alloys: Recent observations have shown that at a certain composition of solid\nsolutions AgCl$_x$Br$_{1-x}$, AgCl-CdCl$_2$, AgBr-CdBr$_2$, of ionic crystals,\nthe electrical conductivity exhibits a value appreciably larger than that of\nthe end constituents. Here, we investigate the electrical conductivity $\\sigma$\nof LiH$_x$D$_{1-x}$ solid solutions -which are of prominent importance in fuel\nhydrogen storage applications- and find that in the whole composition range no\nmaximum is likely to occur in the $\\sigma$ versus x dependence.",
        "positive": "Band Bending Independent of Surface Passivation in\n  ZnO/CdS/Cu(In,Ga)(S,Se)$_2$ Heterojunctions and Cr/Cu(In,Ga)(S,Se)$_2$\n  Schottky Contacts: We have employed admittance spectroscopy and deep-level transient\nspectroscopy in order to investigate the electronic properties of\nZnO/CdS/Cu(In,Ga)(S,Se)$_2$ heterojunctions and Cr/Cu(In,Ga)(S,Se)$_2$ Schottky\ncontacts. Our work concentrates on the origin of an energy-distributed defect\nstate commonly found in these systems. The activation energy of the defect\nstate addressed continuously shifts upon air annealing or damp-heat treatment\nand is a valuable measure of the degree of band bending in\nCu(In,Ga)(S,Se)$_2$-based junctions. We demonstrate that the band bending\nwithin the Cu(In,Ga)(S,Se)$_2$ layer, reported in the literature to become\nminimal after air exposure, returns after the formation of either a Schottky\ncontact or a heterojunction. The earlier phenomenon turns out to be independent\nof a surface passivation due to the CdS bath deposition."
    },
    {
        "anchor": "Quantum transport observed in films of magnetic topological semimetal\n  EuSb$_2$: We report fabrication of EuSb$_2$ single-crystalline films and investigation\nof their quantum transport. First-principles calculations demonstrate that\nEuSb$_2$ is a magnetic topological nodal-line semimetal protected by\nnonsymmorphic symmetry. Observed Shubnikov-de Haas oscillations with multiple\nfrequency components exhibit small effective masses and two-dimensional\nfield-angle dependence even in a 250 nm thick film, further suggesting possible\ncontributions of surface states. This finding of the high-mobility magnetic\ntopological semimetal will trigger further investigation of exotic quantum\ntransport phenomena by controlling magnetic order in topological semimetal\nfilms.",
        "positive": "Spin - Phonon Coupling in Nickel Oxide Determined from Ultraviolet Raman\n  Spectroscopy: Nickel oxide (NiO) has been studied extensively for various applications\nranging from electrochemistry to solar cells [1,2]. In recent years, NiO\nattracted much attention as an antiferromagnetic (AF) insulator material for\nspintronic devices [3-10]. Understanding the spin - phonon coupling in NiO is a\nkey to its functionalization, and enabling AF spintronics' promise of\nultra-high-speed and low-power dissipation [11,12]. However, despite its status\nas an exemplary AF insulator and a benchmark material for the study of\ncorrelated electron systems, little is known about the spin - phonon\ninteraction, and the associated energy dissipation channel, in NiO. In\naddition, there is a long-standing controversy over the large discrepancies\nbetween the experimental and theoretical values for the electron, phonon, and\nmagnon energies in NiO [13-23]. This gap in knowledge is explained by NiO\noptical selection rules, high Neel temperature and dominance of the magnon band\nin the visible Raman spectrum, which precludes a conventional approach for\ninvestigating such interaction. Here we show that by using ultraviolet (UV)\nRaman spectroscopy one can extract the spin - phonon coupling coefficients in\nNiO. We established that unlike in other materials, the spins of Ni atoms\ninteract more strongly with the longitudinal optical (LO) phonons than with the\ntransverse optical (TO) phonons, and produce opposite effects on the phonon\nenergies. The peculiarities of the spin - phonon coupling are consistent with\nthe trends given by density functional theory calculations. The obtained\nresults shed light on the nature of the spin - phonon coupling in AF insulators\nand may help in developing innovative spintronic devices."
    },
    {
        "anchor": "Light-Tunable Surface State and Hybridization Gap in Magnetic\n  Topological Insulator MnBi$_8$Te$_{13}$: MnBi$_8$Te$_{13}$ is an intrinsic ferromagnetic (FM) topological insulator\nwith different complex surface terminations. Resolving the electronic\nstructures of different termination surfaces and manipulation of the electronic\nstate are important. Here, by using micrometer spot time- and angle-resolved\nphotoemission spectroscopy ($\\mu$-TrARPES), we resolve the electronic\nstructures and reveal the ultrafast dynamics upon photoexcitation. Photoinduced\nfilling of the surface state hybridization gap is observed for the Bi$_2$Te$_3$\nquintuple layer directly above MnBi$_2$Te$_4$ accompanied by a nontrivial shift\nof the surface state, suggesting light-tunable interlayer interaction.\nRelaxation of photoexcited electrons and holes is observed within 1-2 ps. Our\nwork reveals photoexcitation as a potential control knob for tailoring the\ninterlayer interaction and surface state of MnBi$_8$Te$_{13}$.",
        "positive": "Instabilities and Insulator-Metal transitions in Half-Doped Manganites\n  induced by Magnetic-Field and Doping: We discuss the phase diagram of the two-orbital model of half-doped\nmanganites by calculating self-consistently the Jahn-Teller (JT) distortion\npatterns, charge, orbital and magnetic order at zero temperature. We analyse\nthe instabilities of these phases caused by electron or hole doping away from\nhalf-doping, or by the application of a magnetic-field. For the CE insulating\nphase of half-doped manganites, in the intermediate JT coupling regime, we show\nthat there is a competition between canting of spins (which promotes mobile\ncarriers) and polaronic self-trapping of carriers by JT defects. This results\nin a marked particle-hole asymmetry, with canting winning only on the electron\ndoped side of half-doping. We also show that the CE phase undergoes a\nfirst-order transition to a ferromagnetic metallic phase when a magnetic-field\nis applied, with abrupt changes in the lattice distortion patterns. We discuss\nthe factors that govern the intriguingly small scale of the transition fields.\nWe argue that the ferromagnetic metallic phases involved have two types of\ncharge carriers, localised and band-like, leading to an effective two-fluid\nmodel."
    },
    {
        "anchor": "Layer dependent topological phases and transitions in TaRhTe$_4$: From\n  monolayer and bilayer to bulk: The recently synthesized ternary quasi-2D material TaRhTe$_4$ is a bulk Weyl\nsemimetal with an intrinsically layered structure, which poses the question how\nthe topology of its electronic structure depends on layers separations.\nExperimentally these separations may be changed for instance by intercalation\nof the bulk, or by exfoliation to reach monolayer or few-layer structures. Here\nwe show that in the monolayer limit a quantum spin Hall insulator (QSHI) state\nemerges, employing density functional calculations as well as a minimal\nfour-orbital tight-binding model that we develop. Even for weak spin-orbit\ncouplings the QSHI is present, which has an interesting edge state that\nfeatures Rashba-split bands with quadratic band minima. Further we find that a\nweak topological insulator (WTI) manifests in the bilayer system due to sizable\nintralayer hopping, contrary to the common lore that only weak interlayer\ninteractions between stacked QSHIs lead to WTIs. Stacked bilayers give rise to\na phase diagram as function of the interlayer separation that comprises a Weyl\nsemimetal, WTI and normal insulator phases. These insights on the evolution of\ntopology with dimension can be transferred to the family of layered ternary\ntransition metal tellurides.",
        "positive": "Compositional disorder and its influence on the structural, electronic\n  and magnetic properties of MgC(Ni_{1-x}Co_{x})_{3} alloys using\n  first-principles: First-principles, density-functional based electronic structure calculations\nare carried out for MgC(Ni_{1-x}Co_{x})_{3} alloys over the concentration range\n0\\leq x\\leq1, using Korringa-Kohn-Rostoker coherent-potential approximation\n(KKR CPA) method in the atomic sphere approximation (ASA). The self-consistent\ncalculations are used to study the changes as a function of x in the equation\nof state parameters, total and partial densities of states, magnetic moment and\nthe on-site exchange interaction parameter. To study the magnetic properties as\nwell as its volume dependence, fixed-spin moment calculations in conjunction\nwith the phenomenological Landau theory are employed. The salient features that\nemerge from these calculations are (i) a concentration independent variation in\nthe lattice parameter and bulk modulus at x~0.75 with an anomaly in the\nvariation of the pressure derivative of bulk modulus, (ii) the fixed-spin\nmoment based corrections to the overestimated magnetic ground state for 0.0\\leq\nx\\leq0.3 alloys, making the results consistent with the experiments, and (iii)\nthe possibility of multiple magnetic states at x~0.75, which, however, requires\nfurther improvements in the calculations."
    },
    {
        "anchor": "Unexpected Near-Infrared to Visible Non-linear Optical Properties from\n  Two-Dimensional Polar Metals: Near-infrared-to-visible second harmonic generation from air-stable\ntwo-dimensional polar gallium and indium metals is described. The photonic\nproperties of 2D metals - including the largest second-order susceptibilities\nreported for metals (approaching 10nm$^2$/V) - are determined by the\natomic-level structure and bonding of two-to-three-atom-thick crystalline\nfilms. The bond character evolved from covalent to metallic over a few atomic\nlayers, changing the out-of-plane metal-metal bond distances by approximately\nten percent (0.2 $\\unicode{x212B}$), resulting in symmetry breaking and an\naxial electrostatic dipole that mediated the large nonlinear response. Two\ndifferent orientations of the crystalline metal atoms, corresponding to lateral\ndisplacements < 2 $\\unicode{x212B}$, persisted in separate micron-scale\nterraces to generate distinct harmonic polarizations. This strong atomic-level\nstructure-property interplay suggests metal photonic properties can be\ncontrolled with atomic precision.",
        "positive": "Optical response and band structure of LiCoO2 including electron-hole\n  interaction effects: The optical response functions and band structures of LiCoO$_2$ are studied\nat different levels of approximation, from density functional theory (DFT) in\nthe generalized gradient approximation (GGA) to quasiparticle self-consistent\nQS$GW$ (with $G$ for Green's function and $W$ for screened Coulomb interaction)\nwithout and with ladder diagrams (QS$G\\hat W$) and the Bethe Salpeter Equation\n(BSE) approach. The QS$GW$ method is found to strongly overestimate the band\ngap and electron-hole or excitonic effects are found to be important. They\nlower the quasiparticle gap by only about 11~\\% but the lowest energy peaks in\nabsorption are found to be excitonic in nature. The contributions from\ndifferent band to band transitions and the relation of excitons to band-to-band\ntransitions are analyzed. The excitons are found to be strongly localized. A\ncomparison to experimental data is presented."
    },
    {
        "anchor": "High temperature thermal cycling effect on the irreversible responses of\n  lattice structure, magnetic properties and electrical conductivity in\n  Co$_{2.75}$Fe$_{0.25}$O$_{4+\u03b4}$ spinel oxide: We report high temperature synchrotron X-ray diffraction (SXRD), dc\nmagnetization and current-voltage (I-V) characteristics for the samples of\nCo$_{2.75}$Fe$_{0.25}$O$_4$ ferrite. The material was prepared by chemical\nreaction of the Fe and Co nitrate solutions at pH = 11 and subsequent annealing\nat temperatures 200 0C, 500 0C and 900 0C. The measurements were performed by\ncycling the temperature from 300 K to high temperature (warming mode) and\nreturn back to 300 K (cooling mode). The SXRD patterns indicated a fine\nbi-phased cubic spinel structure in the highly Co rich spinel oxide.\nMagnetization curves showed intrinsic ferrimagnetic features and defect induced\nadditional ferromagnetic phase at higher temperatures. Electrical conductivity\nshowed thermal hysteresis loop between warming and cooling modes of temperature\nvariation. The samples exhibited new information on the irreversibility\nphenomena of lattice structure, magnetization and electrical conductivity on\ncycling the measurement temperatures.",
        "positive": "Effects of Substrate Temperature on Indium Gallium Nitride Nanocolumn\n  Crystal Growth: Indium gallium nitride films with nanocolumnar microstructure were deposited\nwith varying indium content and substrate temperatures using plasma-enhanced\nevaporation on amorphous SiO2 substrates. FESEM and XRD results are presented,\nshowing that more crystalline nanocolumnar microstructures can be engineered at\nlower indium compositions. Nanocolumn diameter and packing factor (void\nfraction) was found to be highly dependent on substrate temperature, with\nthinner and more closely packed nanocolumns observed at lower substrate\ntemperatures."
    },
    {
        "anchor": "Ferroelectricity at the extreme thickness limit in the archetypal\n  antiferroelectric PbZrO$_3$: Size-driven transition of an antiferroelectric into a polar ferroelectric or\nferrielectric state is a strongly debated issue from both experimental and\ntheoretical perspectives. While critical thickness limits for such transitions\nhave been explored, a bottom-up approach in the ultrathin limit considering few\natomic layers could provide insight into the mechanism of stabilization of the\npolar phases over the antipolar phase seen in bulk PbZrO$_3$. Here, we use\nfirst-principles density functional theory to predict the stability of polar\nphases in Pt/PbZrO$_3$/Pt nanocapacitors. In a few atomic layer thick slabs of\nPbZrO$_3$ sandwiched between Pt electrodes, we find that the polar phase\noriginating from the well established R3c phase of bulk PbZrO$_3$ is\nenergetically favorable over the antipolar phase originating from the Pbam\nphase of bulk PbZrO$_3$. The famous triple-well potential of antiferroelectric\nPbZrO$_3$ is modified in the nanocapacitor limit in such a way as to swap the\npositions of the global and local minima, stabilizing the polar phase relative\nto the antipolar one. The size effect is decomposed into the contributions from\ndimensionality reduction, surface charge screening, and interfacial relaxation,\nwhich reveals that it is the creation of well-compensated interfaces that\nstabilizes the polar phases over the antipolar ones in nanoscale PbZrO$_3$.",
        "positive": "Artificial gravity field, astrophysical analogues, and topological phase\n  transitions in strained topological semimetals: Effective gravity and gauge fields are emergent properties intrinsic for\nlow-energy quasiparticles in topological semimetals. Here, taking two Dirac\nsemimetals as examples, we demonstrate that applied lattice strain can generate\nwarped spacetime, with fascinating analogues in astrophysics. Particularly, we\nstudy the possibility of simulating black-hole/white-hole event horizons and\ngravitational lensing effect. Furthermore, we discover strain-induced\ntopological phase transitions, both in the bulk materials and in their thin\nfilms. Especially in thin films, the transition between the quantum spin Hall\nand the trivial insulating phases can be achieved by a small strain, naturally\nleading to the proposition of a novel piezo-topological transistor device.\nPossible experimental realizations and analogue of Hawking radiation effect are\ndiscussed. Our result bridges multiple disciplines, revealing topological\nsemimetals as a unique table-top platform for exploring interesting phenomena\nin astrophysics and general relativity; it also suggests realistic materials\nand methods to achieve controlled topological phase transitions with great\npotential for device applications."
    },
    {
        "anchor": "Universal Self-Similar Attractor in the Bending-Driven Leveling of Thin\n  Viscous Films: We study theoretically and numerically the bending-driven leveling of thin\nviscous films within the lubrication approximation. We derive the Green's\nfunction of the linearized thin-film equation and further show that it\nrepresents a universal self-similar attractor at long times. As such, the\nrescaled perturbation of the film profile converges in time towards the\nrescaled Green's function, for any summable initial perturbation profile. In\naddition, for stepped axisymmetric initial conditions, we demonstrate the\nexistence of another, short-term and one-dimensional-like self-similar regime.\nBesides, we characterize the convergence time towards the long-term universal\nattractor in terms of the relevant physical and geometrical parameters, and\nprovide the local hydrodynamic fields and global elastic energy in the\nuniversal regime as functions of time. Finally, we extend our analysis to the\nnon-linear thin-film equation through numerical simulations.",
        "positive": "Synthesis of clathrate cerium superhydride CeH9 below 100 GPa with\n  atomic hydrogen sublattice: Hydrogen-rich superhydrides are believed to be very promising high-Tc\nsuperconductors as they are expected to mimic characteristics of metallic\nhydrogen. Recent experiments discovered superhydrides at very high pressures,\ne.g. FeH5 at 130 GPa and LaH10 at 170 GPa. With the motivation of discovering\nnew hydrogen-rich high-Tc superconductors at lowest possible pressure, here we\nreport the prediction and experimental synthesis of cerium superhydride CeH9\nbelow 100 GPa in the laser-heated diamond anvil cell. Ab-initio calculations\nwere carried to evaluate the detailed chemistry of the Ce-H system and to\nunderstand the structure, stability and superconductivity of CeH9. CeH9\ncrystallizes in a P63/mmc clathrate structure with a substantially dense\n3-dimensional hydrogen sublattice at 100 GPa. These findings shed a new light\non the search for superhydrides in close proximity with atomic hydrogen within\na feasible pressure range. Discovery of superhydride CeH9 provides a practical\nplatform to further investigate and understand conventional superconductivity\nin hydrogen rich superhydrides."
    },
    {
        "anchor": "Magnetization reversal process and nonlinear magneto-impedance in\n  Cu/NiFe and Nb/NiFe composite wires: The magnetization reversal of Cu/NiFe and Nb/NiFe composite wires carrying AC\ncurrent is studied. The frequency spectrum of a voltage induced in a pick-up\ncoil wound around the wire is analyzed. The frequency spectrum is shown to\nconsist of even harmonics within a wide range of AC current amplitudes and\nlongitudinal DC magnetic fields. The strong dependencies of the harmonic\namplitudes on the DC field are found. The results obtained may be of importance\nfor the design of weak magnetic field sensors.",
        "positive": "Ferroelectricity in (Pb$_y$Sn$_{1-y}$)$_2$P$_2$S$_6$ mixed crystals and\n  random field BEG model: For Sn$_2$P$_2$S$_6$ ferroelectrics the second order phase transitions line\nis observed until reaching the tricritical point at transition temperature\nlowering to 250 K by compression. Observed temperature-pressure phase diagram\nagrees with simulated diagram by MC calculations based on early founded by DFT\nstudy local potential for Sn$_2$P$_2$S$_6$ crystals. In addition to the\ntricritical point, the possibility of disordered and quadrupolar phases\noccurrence was shown. For mixed crystals with tin by lead substitution, the\ninvestigated ultrasound, hypersound and low frequency dielectric properties\nalso reveal appearance of heterophase peculiarities at decreasing of\nferroelectric transition temperature below so named \"temperature waterline\"\nnear 250~K. The tricriticality at similar temperature level also appears in\nmixed crystals at sulfur by selenium substitution. Such behavior agree with\nBlume-Emery-Griffiths (BEG) model, that is appropriated for investigated\nferroelectric system with three-well local potential for the order parameter\n(spontaneous polarization) fluctuations."
    },
    {
        "anchor": "\"Annular\" ferroelectric domains in hexagonal manganites: Structural features of ferroic domains are fundamentally important for the\nunderstanding of microstructure and physical properties of ferroic materials,\nand they are also of technological significance for information storage and\nelectronic switches. There are three well-known forms of ferroic orders in\ncorrelation with the spontaneous magnetization, electric polarization, and\nspontaneous strain, respectively. Ferroelectricity often accompanies\nferroelastic strain, so ferroelectric domains tend to form in simple elongated\nconfigurations. However, due to strong boundary conditions, ferroelectric\ndomains in nano-materials or near defects can have unusual configurations. In\naddition, vortex domains where multiple ferroelectric domains merge at one\npoint have been observed in YMnO3. Herein, we report the discovery of unique\nferroelectric domains with a concentric cylindrical shape in hexagonal\nmanganites. We have also observed remarkable domains with multiple annular\npatterns. Our findings could open a new avenue for comprehensive studies of the\nferroic domains, and this novel pattern could also leads to possibilities for\nnew technologic applications.",
        "positive": "Use of a Virtual Laboratory to plan, execute and analyse Neutron Strain\n  Scanning experiments: The new generation of dedicated Engineering Strain Scanners at neutron\nfacilities such as ENGIN-X at ISIS and SMARTS at LANSCE offer considerable\nincreases in both the throughput of samples and the density of measurements\nwhich are feasible within each sample. This trend is set to increase further\nwith new neutron sources such as the SNS. In order to make full use of these\nadvances the routine processes associated with setting up measurements, and\nanalysing data need to be made as efficient as possible. This issue has been\naddressed on ENGIN-X by writing a new piece of software which provides support\nfor many of these operations. The approach is based on a virtual lab consisting\nof three dimensional models of the sample and lab equipment such as collimators\nand positioner. A typical session using the package would be; 1) Generate the\nsample model using primitives or from surface points measured with a coordinate\nmeasurement machine, 2) Specify fiducial and measurement points on screen, 3)\nLocate the sample model within the virtual and real laboratories, 4) Execute\nthe measurement sequence using automatically generated machine control scripts,\n5). Analyse the data, 6). Display data using a variety of options including\nsuperimposed on the sample model. The inclusion of an accurate sample model\nwithin the virtual lab allows many other useful properties such as neutron path\nlengths and measurement gauge volumes to be determined; it is also a relatively\nsimple matter to check for possible collisions between sample and lab equipment\nsuch as collimators thereby avoiding potentially costly mistakes. The software\nwhich is shortly to be installed at ENGIN-X has been designed with visiting\nindustrial and academic researchers in mind; users who need to be able to\ncontrol the instrument after only a short period of training."
    },
    {
        "anchor": "The dynamics of cracks in torn thin sheets: Motivated by recent experiments, we present a study of the dynamics of cracks\nin thin sheets. While the equations of elasticity for thin plates are well\nknown, there remains the question of path selection for a propagating crack. We\ninvoke a generalization of the principle of local symmetry to provide a\ncriterion for path selection and demonstrate qualitative agreement with the\nexperimental findings. The nature of the singularity at the crack tip is\nstudied with and without the interference of nonlinear terms.",
        "positive": "Growth diagram and magnetic properties of hexagonal LuFe$_2$O$_4$ thin\n  films: A growth diagram of Lu-Fe-O compounds on MgO (111) substrates using pulsed\nlaser deposition is constructed based on extensive growth experiments.\n  The LuFe$_2$O$_4$ phase can only be grown in a small range of temperature and\nO$_2$ pressure conditions.\n  An understanding of the growth mechanism of Lu-Fe-O compound films is offered\nin terms of the thermochemistry at the surface.\n  Superparamagnetism is observed in LuFe$_2$O$_4$ film and is explained in\nterms of the effect of the impurity h-LuFeO$_3$ phase and structural defects ."
    },
    {
        "anchor": "Mg decorated Boron doped Graphene for Hydrogen Storage: First principles based DFT calculations performed to insight structural and\nelectronic properties of Boron doped Magnesium atom decorated graphene sheet\nfor application of hydrogen storage. The four H2 molecules stably binds\nmagnesium atom with Boron doped graphene sheet. The average binding energy\nextracted in the range-0.566 to -0.687 eV/H2.Partial density of states of\ncomplex system shows s and d orbitals of H2 molecule and Mg atom at -0.1eV\noverlaps of main peaks indicates strong hybridizing and binding of s and d\norbitals of H2 and Mg atom respectively. The gravimetric capacity of studied\ncomplex system reaching approximately 8.26 wt% hydrogen. HOMO & LUMO study\nshows stability of complex system.DOS investigation reveals the electronic\ndensity of states of complex system.",
        "positive": "Principal spectra describing magnetooptic permittivity tensor in cubic\n  crystals: We provide unified phenomenological description of magnetooptic effects being\nlinear and quadratic in magnetization. The description is based on few\nprincipal spectra, describing elements of permittivity tensor up to the second\norder in magnetization. Each permittivity tensor element for any magnetization\ndirection and any sample surface orientation is simply determined by weighted\nsummation of the principal spectra, where weights are given by crystallographic\nand magnetization orientations. The number of principal spectra depends on the\nsymmetry of the crystal. In cubic crystals owning point symmetry we need only\nfour principal spectra. Here, the principal spectra are expressed by ab-initio\ncalculations for bcc Fe, fcc Co and fcc Ni in optical range as well as in hard\nand soft x-ray energy range, i.e. at the 2p- and 3p-edges. We also express\nprincipal spectra analytically using modified Kubo formula."
    },
    {
        "anchor": "Charge carrier solvation and large polaron formation on a polymer chain\n  revealed in model ab initio computations: When an excess charge carrier is added to a semiconducting polymer chain, it\nis well known that the carrier may self-trap into a polaronic state accompanied\nby a bond length adjustment pattern. A different mechanism of self-localization\nis the solvation of charge carriers expected to take place when the polymer\nchain is immersed in polar media such as common solvents. We use\nstate-of-the-art ab initio computations in conjunction with the Polarizable\nContinuum Model to unequivocally demonstrate solvation-induced self-consistent\ncharge localization into large-radius one-dimensional (1D) polarons on long\n$C_{N}H_{2}$ carbon chains with the polyynic structure. Within the framework\nused, the solvation results in a much more pronounced charge localization. We\nbelieve this mechanism of polaron formation to be of relevance for various 1D\nsemiconductors in polar environments.",
        "positive": "Computational Design of Anisotropic Stealthy Hyperuniform Composites\n  with Engineered Directional Scattering Properties: Disordered hyperuniform materials are an emerging class of exotic amorphous\nstates of matter that endow them with singular physical properties. Here, we\ngeneralize the Fourier-space based numerical construction procedure for\ndesigning {\\it isotropic} disordered hyperuniform two-phase heterogeneous\nmaterials (i.e., composites) developed by Chen and Torquato [Acta Mater. {\\bf\n142}, 152 (2018)] to {\\it anisotropic} microstructures by explicitly\nincorporating the {\\it vector-dependent} spectral density function ${\\tilde\n\\chi}_{_V}({\\bf k})$ of {\\it arbitrary form} that is realizable. We demonstrate\nthe utility of the procedure by generating a wide spectrum of {\\it anisotropic}\nstealthy hyperuniform (SHU) microstructures with ${\\tilde \\chi}_{_V}({\\bf k}) =\n0$ for ${\\bf k} \\in \\Omega$. We show how different exclusion-region shapes with\nvarious discrete symmetries and varying size affect the resulting statistically\nanisotropic microstructures as a function of the and phase volume fraction. We\nfind that, among other properties, the directional hyperuniform behaviors\nimposed by the shape asymmetry (or anisotropy) of certain exclusion regions\ngive rise to distinct anisotropic structures and degree of uniformity in the\ndistribution of the phases on intermediate and large length scales along\ndifferent directions. Moreover, while the anisotropic exclusion regions impose\nstrong constraints on the {\\it global} symmetry of the resulting media, they\ncan still possess almost isotropic {\\it local} structures. Our construction\nalgorithm enables one to control the statistical anisotropy of composite\nmicrostructures which is crucial to engineering directional optical, transport\nand mechanical properties of two-phase composite media."
    },
    {
        "anchor": "Rational design of piezoelectric metamaterials with tailored\n  electro-momentum coupling: Piezoelectric materials have wide sensing and energy transduction\napplications due to their inherent coupling of mechanical deformation and\nelectric field. Recent discoveries have revealed that asymmetric or\nheterogeneous microstructures of piezoelectric composites can create an\nadditional coupling of macroscopic momentum to an electric field termed\nelectro-momentum coupling, introducing a new degree of design freedom. In this\nwork, by employing the homogenization scheme, the physical origin of\nelectro-momentum coupling is explored by a high throughput sweep over the\nmicrostructure design space of a piezoelectric composite system. This study\nshows how material constituent properties and geometrical arrangements can\naffect electro-momentum coupling and be smartly tailored for applications of\ninterest.",
        "positive": "Pressure Evolution of Magnetism in URhGa: In this paper, we report the results of an ambient and high pressure study of\na 5f-electron ferromagnet URhGa. The work is focused on measurements of\nmagnetic and thermodynamic properties of a single crystal sample and on the\nconstruction of the p-T phase diagram. Diamond anvil cells were employed to\nmeasure the magnetization and electrical resistivity pressures up to ~ 9 GPa.\nAt ambient pressure, URhGa exhibits collinear ferromagnetic ordering of uranium\nmagnetic moments {\\mu}U ~ 1.1 {\\mu}B (at 2 K) aligned along the c-axis of the\nhexagonal crystal structure below the Curie temperature TC = 41K. With the\napplication of pressure up to 5GPa the ordering temperature TC initially\nincreases whereas the saturated moment slightly decreases. The rather\nunexpected evolution is put in the context of the UTX family of compounds."
    },
    {
        "anchor": "Excitons under strain: light absorption and emission in strained\n  hexagonal boron nitride: Hexagonal boron nitride is an indirect band gap material with a strong\nluminescence in the ultraviolet. This luminescence originates from bound\nexcitons recombination assisted by different phonon modes. The coupling between\nexcitons and phonons is so strong that the resulting light emission is as\nefficient as the one of direct band gap materials. In this manuscript we\ninvestigate how uniaxial strain modifies the electronic and optical properties\nof this material, and in particular how it affects the exciton-phonon coupling.\nUsing a formulation of this coupling based on finite-difference displacements,\nrecently developed by some of us, we investigate how phonon-assisted\ntransitions change under strain. Our results open the way to the study of\nphonon-assisted luminescence in strained materials from first principles. Our\nfindings are important both for experiments that directly probe \\hbn under\nstrain or for those in which it is used as substrate for other 2D material with\na lattice mismatch.",
        "positive": "Bloch-type magnetic skyrmions in two-dimensional lattice: Magnetic skyrmions in two-dimensional lattice are a prominent topic of\ncondensed matter physics and material science. Current research efforts in this\nfield are exclusively constrained to Neel-type and antiskyrmion, while\nBloch-type magnetic skyrmions are rarely explored. Here, we report the\ndiscovery of Bloch-type magnetic skyrmions in two-dimensional lattice of\nMnInP2Te6, using firstprinciples calculations and Monte-Carlo simulations.\nArising from the joint effect of broken inversion symmetry and strong\nspin-orbit coupling, monolayer MnInP2Te6 presents large Dzyaloshinskii-Moriya\ninteraction. This, along with ferromagnetic exchange interaction and\nout-ofplane magnetic anisotropy, gives rise to skyrmion physics in monolayer\nMnInP2Te6, without needing magnetic field. Remarkably, different from all\nprevious works on two-dimensional lattice,the resultant magnetic skyrmions\nfeature Bloch-type, which is protected by D3 symmetry.Furthermore, the\nBloch-type magnetic bimerons are also identified in monolayer MnTlP2Te6. The\nphase diagrams of these Bloch-type topological magnetisms under magnetic field,\ntemperature and strain are mapped out. Our results greatly enrich the research\non magnetic skyrmions in twodimensional lattice."
    },
    {
        "anchor": "Seebeck coefficient of ionic conductors from Bayesian regression\n  analysis: We propose a novel approach to evaluating the ionic Seebeck coefficient in\nelectrolytes from relatively short equilibrium molecular dynamics simulations,\nbased on the Green-Kubo theory of linear response and Bayesian regression\nanalysis. By exploiting the probability distribution of the off-diagonal\nelements of a Wishart matrix, we develop a consistent and unbiased estimator\nfor the Seebeck coefficient whose statistical uncertainty can be arbitrarily\nreduced in the long-time limit. To validate the effectiveness of our method, we\nbenchmark it against extensive equilibrium molecular dynamics simulations\nconducted on molten $\\mathrm{CsF}$ using empirical force fields. We then employ\nthis procedure to calculate the Seebeck coefficient of molten $\\mathrm{NaCl}$,\n$\\mathrm{KCl}$ and $\\mathrm{LiCl}$ using neural-network force fields trained on\n\\textit{ab initio} data over a range of pressure-temperature conditions.",
        "positive": "Large band splitting with tunable spin polarization in two-dimensional\n  ferroelectric GaXY (X= Se, Te; Y= Cl, Br, I) family: It has been generally accepted that the spin-orbit coupling effect in\nnoncentrosymmetric materials leads to the band splitting and non-trivial spin\npolarization in the momentum space. However, in some cases, zero net spin\npolarization in the split bands may occurs, dubbed as the band splitting with\nvanishing spin polarization (BSVSP) effect, protected by non-pseudo-polar point\ngroup symmetry of the wave vector in the first Brillouin zone [Liu et. al.,\nNat. Commun. \\textbf{10}, 5144 (2019)]. In this paper, by using\nfirst-principles calculations, we show that the BSVSP effect emerges in\ntwo-dimensional (2D) nonsymmorphic Ga$XY$ ($X$= Se, Te; $Y$= Cl, Br, I) family,\na new class of 2D materials having in-plane ferroelectricity. Taking the GaTeCl\nmonolayer as a representative example, we observe the BSVSP effect in the split\nbands along the $X-M$ line located in the proximity of the conduction band\nminimum. By using $\\vec{k}\\cdot\\vec{p}$ Hamiltonian derived based on the\nsymmetry analysis, we clarify that such effect is originated from the\ncancellation of the local spin polarization, enforced by non-pseudo-polar\n$C_{2v}$ point group symmetry of the wave vector along the $X-M$ line.\nImportantly, we find that the spin polarization can be effectively induced by\napplying an external out-of-plane electric field, indicating that an\nelectrically tunable spin polarization for spintronic applications is\nplausible."
    },
    {
        "anchor": "Electronic structures near unmovable nodal points and lines in\n  two-dimensional materials: Unmovable nodal points (UNP) and lines (UNL) are band crossings which\npositions in the Brillouin zone are unaltered by symmetry preserving\nperturbations. Not only positions but also the band structure in the vicinity\nis determined by the little group of a wave vector and it's irreducible\n(co)representations. In this paper we give the full set of electronic\ndispersions near all UNPs and UNLs in non-magnetic, quasi two-dimensional (2D)\nmaterials both with and without spin-orbit coupling (SOC). Analysis of all\nlayer gray single and double groups gives nineteen different quasiparticles,\ngreat majority of which are unavoidable for a 2D material which belongs to\ncertain layer groups. These include Weyl and Dirac nodal lines, dispersions\nwith quadratic or cubic splitting, anisotropic Weyl and Dirac cones which\norientation can be varied by e.g. strain etc. We indicated qusiparticles that\nare robust to SOC. For convenience, our results are concisely presented\ngraphically - as a map, not in a tabular, encyclopedia form. They may be of use\nas checkpoints or for fitting of experimentally (via e.g. ARPES) and\nnumerically obtained electronic band structures as well as for deeper\ntheoretical investigations.",
        "positive": "Half Metallicity in Hybrid BCN Nanoribbons: We report a first-principles electronic-structure calculation on C and BN\nhybrid zigzag nanoribbons. We find that half-metallicity can arise in the\nhybrid nanoribbons even though stand-alone C or BN nanoribbon possesses a\nfinite band gap. This unexpected half-metallicity in the hybrid nanos-tructures\nstems from a competition between the charge and spin polarizations, as well as\nfrom the pi orbital hybridization between C and BN. Our results point out a\npossibility of making spintronic devices solely based on nanoribbons and a new\nway of designing metal-free half metals."
    },
    {
        "anchor": "Ironsilicide formation by high temperature codeposition of Fe-2Si with\n  different thicknesses on Si (111): Fe and 2Si were co-deposited on Si (111) surface at 853 K. The formation of\nsilicides was investigated by Mossbauer spectroscopy and electron microscopy.\nDepending on the thickness of the deposited films different phases were formed.\nAt low thickness, stable $\\epsilon$-FeSi (B20) and metastable\n[CsCl]-Fe$_{1-x}$Si (B2) phases were observed. In the latter case, because of\nthe presence of Fe vacancies in the lattice the local symmetry around the iron\ncomponents was lower than cubic. At larger (12 nm) deposited thickness, stable\n$\\beta$-FeSi$_2$ has been formed.",
        "positive": "Determination of hole g-factor in InAs/InGaAs/InAlAs quantum wells by\n  magneto-photoluminescence studies: Circularly-polarized magneto-photoluminescence (magneto-PL) technique has\nbeen applied to investigate Zeeman effect in InAs/InGaAs/InAlAs quantum wells\n(QWs) in Faraday geometry. Structures with different thickness of the QW\nbarriers have been studied in magnetic field parallel and tilted with respect\nto the sample normal. Effective electron-hole g-factor has been found by\nmeasurement of splitting of polarized magneto-PL lines. Lande factors of\nelectrons have been calculated using the 14-band kp method and g-factor of\nholes was determined by subtracting the calculated contribution of the\nelectrons from the effective electron-hole g-factor. Anisotropy of the hole\ng-factor has been studied applying tilted magnetic field."
    },
    {
        "anchor": "Characterization of Failure Mechanism in Composite Materials Through\n  Fractal Analysis of Acoustic Emission Signals: In this paper it is presented a detailed numerical investigation of acoustic\nemission signals obtained from test samples of fibreglass reinforced polymeric\nmatrix composites, when subjected to tensile and flexural tests. Various\nfractal indices, characteristic of the signals emitted at the different\nstructural failures of the test samples and which satisfy non-stationary\ndistributions, have been determined. From the results obtained for these\nindices, related to the Hurst analysis, detrended fluctuation analysis, minimal\ncover analysis and to the boxcounting dimension analysis, it has been shown\nthey can discriminate the different failure mechanisms and, therefore, they\nconstitute their signature.",
        "positive": "Solving the De Prony's Problem of Separation of the Overlapping\n  Exponents in DLTS: This paper presents the solution to the De Prony's problem of separation of\nthe overlapping exponents using the binomial coefficient as the weighting\nfactors. The algebraic structure of the signal classes is discussed and the\napplicability of method is demonstrated."
    },
    {
        "anchor": "Understanding Spin Configuration in the Geometrically Frustrated Magnet\n  TbB$_{4}$: a Resonant Soft X-ray Scattering Study: The frustrated magnet has been regarded as a system that could be a promising\nhost material for the quantum spin liquid (QSL). However, it is difficult to\ndetermine the spin configuration and the corresponding mechanism in this\nsystem, because of its geometrical frustration (i.e., crystal structure and\nsymmetry). Herein, we systematically investigate one of the geometrically\nfrustrated magnets, the TbB$_{4}$ compound. Using resonant soft x-ray\nscattering (RSXS), we explored its spin configuration, as well as Tb's\nquadrupole. Comprehensive evaluations of the temperature and photon energy /\npolarization dependences of the RSXS signals reveal the mechanism of spin\nreorientation upon cooling down, which is the sophisticated interplay between\nthe Tb spin and the crystal symmetry rather than its orbit (quadrupole). Our\nresults and their implications would further shed a light on the search for\npossible realization of QSL.",
        "positive": "Flux-closure domains in high aspect ratio electroless-deposited CoNiB\n  nanotubes: We report the imaging of magnetic domains in ferromagnetic CoNiB nanotubes\nwith very long aspect ratio, fabricated by electroless plating. While axial\nmagnetization is expected for long tubes made of soft magnetic materials, we\nevidence series of azimuthal domains. We tentatively explain these by the\ninterplay of anisotropic strain and/or grain size, with magneto-elasticity\nand/or anisotropic interfacial magnetic anisotropy. This material could be\ninteresting for dense data storage, as well as curvature-induced magnetic\nphenomena such as the non-reciprocity of spin-wave propagation."
    },
    {
        "anchor": "Hydrogen sensing characteristics of perovskite based calcium doped\n  BiFeO3 thin films: Perovskite oxide based thin film gas sensors have long been considered as\npotential alternatives to commonly investigated binary metal oxides based\nsensors. BiFeO3, which is a prototype of p-type perovskite based semiconducting\noxides, has recently drawn significant attention for its promising gas sensing\ncharacteristics. In the present work, the hydrogen sensing characteristics of\ncalcium doped BiFeO3 has been reported by varying the film thickness, doping\nconcentration, operating temperature, and test gas concentration. The films\nwere deposited on glass substrates by sol-gel route using spin coating. X-ray\ndiffraction analyses confirmed formation of phase pure films and scanning\nelectron microscopy confirmed their uniform and dense microstructure. The\nCa-doped BiFeO3 sensors exhibit higher sensitivity compared to pure BiFeO3\nsensors. It is reported that the film thickness and Ca doping concentration\nplay major role to control hydrogen sensing characteristics of the deposited\nfilms. The sensor based on 15% Ca-doped BiFeO3 sensor exhibited very high\nsensitivity (~212 % at 500 ppm H2), and excellent selectivity towards hydrogen\nat a moderate operating temperature (~250 {\\deg}C).The enhanced gas sensing\nresponse of the doped BiFeO3 films has been attributed to the higher oxygen\nvacancy concentration induced by incorporation of aliovalent Ca2+.",
        "positive": "Trapping photon-dressed Dirac electrons in a quantum dot studied by\n  coherent two dimensional photon echo spectroscopy: We study the localization of dressed Dirac electrons in a cylindrical quantum\ndot (QD) formed on monolayer and bilayer graphene by spatially different\npotential profiles. Short lived excitonic states which are too broad to be\nresolved in linear spectroscopy are revealed by cross peaks in the photon-echo\nnonlinear technique. Signatures of the dynamic gap in the two-dimensional\nspectra are discussed. The effect of the Coulomb induced exciton-exciton\nscattering and the formation of biexciton molecules are demonstrated."
    },
    {
        "anchor": "High quality atomically thin PtSe2 films grown by molecular beam epitaxy: Atomically thin PtSe2 films have attracted extensive research interests for\npotential applications in high-speed electronics, spintronics and\nphotodetectors. Obtaining high quality, single crystalline thin films with\nlarge size is critical. Here we report the first successful layer-by-layer\ngrowth of high quality PtSe2 films by molecular beam epitaxy. Atomically thin\nfilms from 1 ML to 22 ML have been grown and characterized by low-energy\nelectron diffraction, Raman spectroscopy and X-ray photoemission spectroscopy.\nMoreover, a systematic thickness dependent study of the electronic structure is\nrevealed by angle-resolved photoemission spectroscopy (ARPES), and helical spin\ntexture is revealed by spin-ARPES. Our work provides new opportunities for\ngrowing large size single crystalline films for investigating the physical\nproperties and potential applications of PtSe2.",
        "positive": "Oxygen Functionalization-induced Crossover in the Tensile Properties of\n  thinnest 2D Ti2C MXene: Transition metal carbides/nitrides (MXenes) are a newly developing class of\ntwo-dimensional (2D) materials with technically robust properties that can be\nfinely tuned by planar surface functionalization. Herein, the critical role of\noxygen (O-) functionalization on the tensile mechanical characteristics of\nthinnest 2D Ti2C MXene is explored by molecular dynamic (MD) simulation with\nfirst-principle based ReaxFF forcefield. It is demonstrated that Ti2C sheet\nshows unique tensile mechanical behaviors that pronouncedly vary with the\ncontent of O-functionalization and stretching direction. Upon both loading\ndirections, there is an apparent crossover in the Young's modulus, failure\nstrength and failure strain. Intriguingly, under armchair directional load, a\nstructural transition of 1T to 1T' phase occurs in the Ti2C region, which has\nbeen observed in many transition metal dichalcogenides. Upon zigzag directional\nstraining, however, two distinct structural transformations take place in\npristine and fully O-functionalized Ti2C sheets, respectively. As the load is\nremoved, those three structural transformations are reversible, and they are\ncritically understood by analysis of the bond configurations. The study\nprovides important insights into mechanical behaviors and structural\ntransformations of functionalized MXenes."
    },
    {
        "anchor": "First-principles Study of Rashba Effect in Ultra-thin Bismuth Surface\n  Alloys: We performed density functional calculations for ultra-thin bismuth surface\nalloys: surface alloys of bismuth and face-centered cubic metals\nBi/$M$(111)-$(\\sqrt{3}\\times\\sqrt{3})R30\\deg$ ($M$=Cu, Ag, Au, Ni, Co, and Fe).\nOur calculated Rashba parameters for the Bi/Ag are consistent with the previous\nexperimental and theoretical results. We predicted a trend in the Rashba\ncoefficients $\\alpha_R$ of bands around the Fermi energy for noble metals as\nfollows: Bi/Ag > Bi/Cu > Bi/Au. As for the transition metals, there is a trend\nin $\\alpha_R$: Bi/Ni > Bi/Co > Bi/Fe. Our finding may lead to design efficient\nspin-charge conversion materials.",
        "positive": "Dynamic effects on the loss of control in template-directed nucleation: Full nucleation control for deposited functional molecules on pre-patterned\nsurfaces is of major technological relevance. To understand the nucleation\nbehavior we combine the numerical solution for the evolution of the adatom\nconcentration with standard nucleation theory. From the qualitative change in\nnucleation behavior upon variation of the pattern spacing and coverage we show\nwhy the quality of nucleation control can vary significantly in different\nparameter regimes. In some limits analytical expressions can be formulated for\nthe nucleation control. Our analysis provides a theoretical explanation for\nprevious experimental observations [Wang et al, PRL 98, 225504 (2007)]."
    },
    {
        "anchor": "Covalent pathways in engineering h-BN supported graphene: Cross-planar di-vacancies (CPDVs) within stacked graphene hexagonal boron\nnitride (h-BN) heterostructures provide stabilized covalent links to bridge\nadjacent graphene and h-BN sheets. It was shown that the CPDVs serve as focal\npoints for cross-planar atom transport between graphene and h-BN, and the\nchemical nature of interlayer links along with associated cross-planar\nmigration pathways at these defects can be predictively manipulated through\nmodulation of the chemical environment and charge engineering, to achieve\nconsistent B or N doping and simultaneous healing of graphene. The present\nstudy proposed a viable approach integrating irradiation, chemical and charge\nengineering, to produce high-quality graphene with tunable electronic and\nelectrochemical properties, using the h-BN substrate.",
        "positive": "Adatom incorporation and step crossing at the edges of 2D nanoislands: Adatom incorporation into the ``faceted'' steps bordering the 2D nanoislands\nis analyzed. The step permeability and incorporation coefficients are derived\nfor some typical growth situations. It is shown that the step consisting of\nequivalent straight segments can be permeable even in the case of fast egde\nmigration if there exist factors delaying creation of new kinks. The step\nconsisting of alternating rough and straight segments may be permeable if there\nis no adatom transport between neighboring segments through the corner\ndiffusion."
    },
    {
        "anchor": "Quantum-continuum simulation of underpotential deposition at electrified\n  metal-solution interfaces: The underpotential deposition of transition metal ions is a critical step in\nmany electrosynthetic approaches. While underpotential deposition has been\nintensively studied at the atomic level, first-principles calculations in\nvacuum can strongly underestimate the stability of underpotentially deposited\nmetals. It has been shown recently that the consideration of co-adsorbed anions\ncan deliver more reliable descriptions of underpotential deposition reactions;\nhowever, the influence of additional key environmental factors such as the\nelectrification of the interface under applied voltage and the activities of\nthe ions in solution have yet to be investigated. In this work, copper\nunderpotential deposition on gold is studied under realistic electrochemical\nconditions using a quantum-continuum model of the electrochemical interface. We\nreport here on the influence of surface electrification, concentration effects,\nand anion co-adsorption on the stability of the copper underpotential\ndeposition layer on the gold (100) surface.",
        "positive": "On the origin of supertetragonality in BaTiO$_3$: Understanding ferroelectricity is of both fundamental and technological\nimportance to further stimulate the development of new materials designs and\nmanipulations. Here, we perform an in-depth first-principle study on the\nwell-known ferroelectric barium titanate BaTiO$_{3}$ under a hydrostatic\nnegative pressure, showing an isosymmetric phase transition to a\nsupertetragonal phase with high $c/a$ ratio of $\\sim1.3$. The microscopic\norigin and driving mechanisms of this phase transition are identified as a\ndrastic change of the covalently $\\pi$-bonded electrons. These findings provide\nguidance in the search for new supertetragonal phases, with great opportunities\nfor novel multiferroic materials; and can be generalized in the understanding\nof other isosymmetric phase transitions."
    },
    {
        "anchor": "Density Functional Theory of Freezing and Phase Field Crystal Modeling: In this paper the relationship between the density functional theory of\nfreezing and phase field modeling is examined. More specifically a connection\nis made between the correlation functions that enter density functional theory\nand the free energy functionals used in phase field crystal modeling and\nstandard models of binary alloys (i.e., regular solution model). To demonstrate\nthe properties of the phase field crystal formalism a simple model of binary\nalloy crystallization is derived and shown to simultaneously model\nsolidification, phase segregation, grain growth, elastic and plastic\ndeformations in anisotropic systems with multiple crystal orientations on\ndiffusive time scales.",
        "positive": "Coulomb interaction in a quantum dot: One approximation is made to describe a M+1 electron many-body wavefunction\nby a M electron many-body wavefunction and a single electron wavefunction.\nUnder this approximation, we have derived the Coulomb energy which relates the\nexciton energy $E_{exc}$ in a quantum dot with the quasiparticle band gap\n(defined as the difference between the ionization energy and the electron\naffinity), and the Coulomb energy which relates $E_{exc}$ with the single\nparticle eigen values. We found that these two Coulomb energies are different.\nWe have compared our results with the formulae used in different groups, which\nare proposed either {\\it ad hov}, or from the classical electrostatic point of\nview. We found important difference between our results and the classical\nformula. Finally, under the above approximation, we provided an effective\nsingle particle Hamiltonian, which gives the quasiparticle band structure in a\nbulk system."
    },
    {
        "anchor": "Transition between large and small electron polaron at neutral\n  ferroelectric domain walls in BiFeO$_3$: Ferroelectric domain walls are planes within an insulating material that can\naccumulate and conduct charge carriers, hence the interaction of the domain\nwalls with the charge carriers can be important for photovoltaic and other\nelectronic applications. By means of first principles calculations we predict a\ntransition from a large two-dimensional electron polaron to a small polaron at\nthe domain walls at a critical electron density, with polaron signatures in\noptical absorption and photoluminescence. We find that large and small polarons\nat the domain walls create different absorption peaks within the band gap that\nare not present in the case of pristine domain walls. These are an extended\nDrude peak in the case of large electron or hole polarons and a narrow mid-gap\npeak in the case of the small electron polaron.",
        "positive": "Local Flattening of the Fermi Surface and Quantum Oscillations in the\n  Magnetoacoustic Response of a Metal: In the present work we theoretically analyze the effect of the Fermi surface\nlocal geometry on quantum oscillations in the velocity of an acoustic wave\ntravelling in metal across a strong magnetic field. We show that local\nflattenings of the Fermi surface could cause significant amplification of\nquantum oscillations. This occurs due to enhancement of commensurability\noscillations modulating the quantum oscillations in the electron density of\nstates on the Fermi surface. The amplification in the quantum oscillations\ncould be revealed at fitting directions of the magnetic field."
    },
    {
        "anchor": "The magnetic structure of Li2CuO2: from ab initio calculations to\n  macroscopic simulations: The magnetic structure of the edge sharing cuprate compound Li2CuO2 has been\ninvestigated by means of ab initio electronic structure calculations. The first\nand second neighbor in-chain magnetic interactions are calculated to be -142 K\nand 22 K, respectively. The ratio between the two parameters is smaller than\nsuggested previously in the literature. The interchain interactions are\nantiferromagnetic in nature and of the order of a few Kelvins only. Monte Carlo\nsimulations using the ab initio parameters to define the model Hamiltonian\nresult in a Neel temperature in rather good agreement with experiment. Spin\npopulation analysis situate the magnetic moment on the copper and oxygen ions\nsomewhere between the completely localized picture derived from experiment and\nthe more delocalized picture based on local density calculations.",
        "positive": "Muon Spin Relaxation Measurements on Zirconia Samples: Although of primary importance in the mechanistic understanding of Zircaloy\nhydriding, practically nothing is known on the transport properties of hydrogen\nin zirconia. In this frame the muon, which can be considered as a light\nhydrogen nuclide, can be used as an analogue and its behavior in zirconia and\nZircaloy corrosion layer may provide more insight to understand the behavior of\nhydrogen in these phases. Preliminary muon spin relaxation ($\\mu$SR)\nmeasurements on several monoclinic zirconia samples, including a Zircaloy\ncorrosion layer, have been performed. From the observed muon depolarization\nrate, the muon diffusivity in bulk monoclinic zirconia can be extracted and is\nfound comparable to that of recently reported proton diffusivity."
    },
    {
        "anchor": "Magnetic and magnetoelectric studies in pure and cation doped BiFeO3: We report magnetic and magnetoelectric studies on BiFeO3 and divalent cation\n(A) suvtitute Bi0.7A0.3FeO3 (A = Sr,Ba, and Sr0.5Ba0.5). It is shown that the\nrapid increase of magnetization at the Neel temperature (TN = 642 K) is\nsuppressed in the co-doped compound A = Sr0.5Ba0.5. All the divalent subtituted\ncompounds show enhanced magnetization and hysteresis loop. Both longitudinal\nand transverse magnetoelectric coefficients were measured using the dynamical\nlock-in technique. The co-doped compound shows the highest magnetoelectric\ncoefficient at room temperature although it is not the compound with the\nhighest saturation magnetization. It is found that as the size of the A-site\ncation increses, the transverse magnetoelectric coeffient increases and exceeds\nthe longitudinal magnetoelectric coefficient. It is suggested that changes in\nmagnetic domain structure and magnetostriction are possible reasons for the\nobserved changes in the magnetoelectric coefficients.",
        "positive": "Transferability of force fields for 2D silicon (silicene): An ability of various interatomic potentials to reproduce the properties of\nsilicene (2D silicon) polymorphs were examined. Structural and mechanical\nproperties of the flat (FS), low-buckled (LBS), trigonal dumbbell (TDS),\nhoneycomb dumbbell (HDS) and large honeycomb dumbbell (LHDS) single-layer\nsilicon (silicene) phases, were obtained using density functional theory (DFT)\nand molecular statics (MS) calculations with Tersoff, MEAM, Stillinger-Weber,\nEDIP, ReaxFF, COMB and machine-learning-based (ML-IAP) interatomic potentials.\nA quantitative systematic comparison and discussion of the results obtained are\nreported."
    },
    {
        "anchor": "Approaching the Intrinsic Photoluminescence Linewidth in Transition\n  Metal Dichalcogenide Monolayers: Excitonic states in monolayer transition metal dichalcogenides (TMDCs) have\nbeen the subject of extensive recent interest. Their intrinsic properties can,\nhowever, be obscured due to the influence of inhomogeneity in the external\nenvironment. Here we report methods for fabricating high quality TMDC\nmonolayers with narrow photoluminescence (PL) linewidth approaching the\nintrinsic limit. We find that encapsulation in hexagonal boron nitride (h-BN)\nsharply reduces the PL linewidth, and that passivation of the oxide substrate\nby an alkyl monolayer further decreases the linewidth and also minimizes the\ncharged exciton (trion) peak. The combination of these sample preparation\nmethods results in much reduced spatial variation in the PL emission, with a\nfull-width-at-half-maximum as low as 1.7 meV. Analysis of the PL line shape\nyields a homogeneous width of 1.43$\\pm$0.08 meV and inhomogeneous broadening of\n1.1$\\pm$0.3 meV.",
        "positive": "A fast approximate method for variable-width broadening of spectra: Spectral data is routinely broadened in order to improve appearance,\napproximate a higher sampling level or model experimental measurement effects.\nWhile there has been extensive work in the signal processing field to develop\nefficient methods for the application of fixed-width broadening functions,\nthese are not suitable for all scientific applications -- for example, the\ninstrumental resolution of inelastic neutron scattering measurements varies\nalong the energy-transfer axis. Na\\\"ive application of a kernel to every point\nhas $O(N \\times M)$ complexity and scales poorly for a high-resolution spectrum\nover many data points. Here we present an approximate method with complexity\n$O(N + W\\times M \\log M)$, where $W$ scales with the range of required\nbroadening widths; in practice the number and cost of mathematical operations\nis drastically reduced to $N$ polynomial evaluations and a modest number of\ndiscrete Fourier transforms. Applications are demonstrated for Gaussian\ninterpolation of density-of-states data and to instrumental resolution\nfunctions. We anticipate that these performance improvements will assist\napplication of resolution functions inside fitting procedures and interactive\ntools."
    },
    {
        "anchor": "Interface heat transfer between crossing carbon nanotubes, and the\n  thermal conductivity of nanotube pellets: We theoretically compute the interface thermal resistance between crossing\nsingle walled carbon nanotubes of various chiralities, using an atomistic\nGreen's function approach with semi-empirical potentials. The results are then\nused to model the thermal conductivity of three dimensional nanotube pellets in\nvacuum. For an average nanotube length of 1 $\\mu$m, the model yields an upper\nbound for the thermal conductivity of densely compacted pellets, of the order\nof a few W/m-K. This is in striking contrast with the ultra-high thermal\nconductivity reported on individually suspended nanotubes. The results suggest\nthat nanotube pellets might have an application as thermal insulators.",
        "positive": "Rotational and Dilational Reconstruction in Transition Metal\n  Dichalcogenide Moir\u00e9 Bilayers: Lattice reconstruction and corresponding strain accumulation play a key role\nin defining the electronic structure of two-dimensional moir\\'e superlattices,\nincluding those of transition metal dichalcogenides (TMDs). Imaging of TMD\nmoir\\'es has so far provided a qualitative understanding of this relaxation\nprocess in terms of interlayer stacking energy, while models of the underlying\ndeformation mechanisms have relied on simulations. Here, we use interferometric\nfour-dimensional scanning transmission electron microscopy to quantitatively\nmap the mechanical deformations through which reconstruction occurs in\nsmall-angle twisted bilayer MoS2 and WSe2/MoS2 heterobilayers. We provide\ndirect evidence that local rotations govern relaxation for twisted\nhomobilayers, while local dilations are prominent in heterobilayers possessing\na sufficiently large lattice mismatch. Encapsulation of the moir\\'e layers in\nhBN further localizes and enhances these in-plane reconstruction pathways,\nsuppressing out-of-plane corrugation. We also find that extrinsic uniaxial\nheterostrain, which introduces a lattice constant difference in twisted\nhomobilayers, leads to accumulation and redistribution of reconstruction\nstrain, demonstrating another route to modify the moir\\'e potential."
    },
    {
        "anchor": "In-situ monitoring of room temperature reactions of lanthanides with\n  nitrogen and hydrogen at low pressures: The dissociative chemisorption of molecular nitrogen on clean lanthanide\nsurfaces at ambient temperature and low pressure is explored. In-situ\nconductance measurements track the conversion from the lanthanide metals to the\ninsulating lanthanide nitrides. A small partial pressure of oxygen ($\\sim\n10^{-8}$ mbar) is shown to inhibit the nitridation of lanthanides at $10^{-4}$\nmbar of N$_2$. The rate of nitridation as a function of nitrogen pressure is\nmeasured at low pressure for a series of lanthanide elements, gadolinium,\nterbium, dysprosium, ytterbium and praseodymium. Exposure of the lanthanide\nsurfaces to both N$_2$ and H$_2$ results in the formation of NH$_3$.",
        "positive": "A comparative study of the energetics of CO on stepped and kinked Cu\n  surfaces using density functional theory: Our ab initio calculations of CO adsorption on several low and high miller\nindex surfaces of Cu show that the adsorption energy increases as the\ncoordination of the adsorption site decreases from 11 to 6, in qualitative\nagreement with experimental observations. On each surface the adsorption energy\nis also found to decrease with increase in coverage, although the decrement is\nnot uniform. Calculated vibrational properties show an increase in the\nfrequency of the metal-C mode with decrease in coordination whereas no such\neffect is found in the frequency of the CO stretch mode. Examination of the\nsurface electronic structure shows a strong local effect of CO adsorption on\nthe local density of state of the substrate atoms. We also provide some\nenergetics of CO diffusion on Cu(111) and Cu(211)."
    },
    {
        "anchor": "Quasiparticle band structures, spontaneous polarization, and\n  spin-splitting in noncentrosymmetric few-layer and bulk $\u03b3$-GeSe: Group-IV monochalcogenides have attracted much attention due to their\npotential of ferroelectric and multiferroic properties. Recently,\ncentrosymmetric gamma-phase GeSe in a double-layer honeycomb lattice has been\ntheoretically predicted, but the synthesized gamma-phase GeSe showed a\nnoncentrosymmetric atomic structure, leading to the possibility of\nferroelectricity and spin-splitting. Here, we study the quasiparticle band\nstructures, spontaneous polarization, and spin-splitting in noncentrosymmetric\ngamma-GeSe using density functional theory and GW calculations. Our results\nshow that noncentrosymmetric few-layer and bulk gamma-GeSe have semiconducting\nband structures with indirect band gaps, which depend almost linearly on the\nreciprocal of the number of layers. Spontaneous polarization occurs due to a\nsmall charge transfer between the layers, which increases with compressive\nstrain, and ferroelectric switching can be achieved by an interlayer\ntranslation with a small energy barrier. Spin-splitting is found to be more\nsignificant at the highest valence band than at the lowest conduction band. Our\nresults provide insights into the fundamental electronic properties of a\nlayered ferroelectric semiconductor applicable to devices with\nferroelectric/nonferroelectric junctions.",
        "positive": "Dynamical simulations of polaron transport in conjugated polymers with\n  the inclusion of electron-electron interactions: Dynamical simulations of polaron transport in conjugated polymers in the\npresence of an external time-dependent electric field have been performed\nwithin a combined extended Hubbard model (EHM) and Su-Schrieffer-Heeger (SSH)\nmodel. Nearly all relevant electron-phonon and electron-electron interactions\nare fully taken into account by solving the time-dependent Schr\\\"{o}dinger\nequation for the $\\pi$-electrons and the Newton's equation of motion for the\nbackbone monomer displacements by virtue of the combination of the adaptive\ntime-dependent density matrix renormalization group (TDDMRG) and classical\nmolecular dynamics (MD). We find that after a smooth turn-on of the external\nelectric field the polaron is accelerated at first and then moves with a nearly\nconstant velocity as one entity consisting of both the charge and the lattice\ndeformation. An ohmic region (3 mV/$\\text{\\AA}$ $\\leq E_0\\leq$ 9\nmV/$\\text{\\AA}$) where the stationary velocity increases linearly with the\nelectric field strength is observed for the case of $U$=2.0 eV and $V$=1.0 eV.\nThe maximal velocity is well above the speed of sound. Below 3 mV/$\\text{\\AA}$\nthe polaron velocity increases nonlinearly and in high electric fields with\nstrength $E_0\\geq$ 10.0 mV/$\\text{\\AA}$ the polaron will become unstable and\ndissociate. The relationship between electron-electron interaction strengths\nand polaron transport is also studied in detail. We find that the the on-site\nCoulomb interactions $U$ will suppress the polaron transport and small\nnearest-neighbor interactions $V$ values are also not beneficial to the\npolaronic motion while large $V$ values favor the polaron transport."
    },
    {
        "anchor": "Ferromagnetic phase of spinel compound MgV$_2$O$_4$ and its spintronics\n  properties: Spinel compound, MgV$_2$O$_4$, known as a highly frustrated magnet has been\nextensively studied both experimentally and theoretically for its exotic\nquantum magnetic states. However, due to its intrinsic insulating nature in its\nantiferromagnetic (AFM) ground state, its realistic applications in spintronics\nare quite limited. Here, based on first-principles calculations, we examine the\nferromagnetic (FM) phase of MgV$_2$O$_4$, which was found to host\nthree-dimensional flat band (FB) right near the Fermi level, consequently\nyielding a large anomalous Hall effect (AHE, $\\sigma \\approx\n670\\,\\Omega^{-1}\\cdot cm^{-1}$). Our calculations suggest that the\nhalf-metallicity feature of MgV$_2$O$_4$ is preserved even after interfacing\nwith MgO due to the excellent lattice matching, which could be a promising spin\nfiltering material for spintronics applications. Lastly, we explore\nexperimental feasibility of stabilizing this FM phase through strain and doping\nengineering. Our study suggests that experimentally accessible amount of hole\ndoping might induce a AFM-FM phase transition.",
        "positive": "Formation of dispersive hybrid bands at an organic-metal interface: An electronic band with quasi-one dimensional dispersion is found at the\ninterface between a monolayer of a charge-transfer complex (TTF-TCNQ) and a\nAu(111) surface. Combined local spectroscopy and numerical calculations show\nthat the band results from a complex mixing of metal and molecular states. The\nmolecular layer folds the underlying metal states and mixes with them\nselectively, through the TTF component, giving rise to anisotropic hybrid\nbands. Our results suggest that, by tuning the components of such molecular\nlayers, the dimensionality and dispersion of organic-metal interface states can\nbe engineered."
    },
    {
        "anchor": "Ab initio study of magnesium alanate, Mg(AlH4)2: Magnesium alanate Mg(AlH4)2 has recently raised interest as a potential\nmaterial for hydrogen storage. We apply ab initio calculations to characterize\nstructural, electronic and energetic properties of Mg(AlH4)2. Density\nfunctional theory calculations within the generalized gradient approximation\n(GGA) are used to optimize the geometry and obtain the electronic structure.\nThe latter is also studied by quasi-particle calculations at the GW level.\nMg(AlH4)2 is a large band gap insulator with a fundamental band gap of 6.5 eV.\nThe hydrogen atoms are bonded in AlH4 complexes, whose states dominate both the\nvalence and the conduction bands. On the basis of total energies, the formation\nenthalpy of Mg(AlH4)2 with respect to bulk magnesium, bulk aluminum and\nhydrogen gas is 0.17 eV/H2 (at T = 0). Including corrections due to the zero\npoint vibrations of the hydrogen atoms this number decreases to 0.10 eV/H2. The\nenthalpy of the dehydrogenation reaction Mg(AlH4)2 -> MgH2 +2Al+3H2(g) is close\nto zero, which impairs the potential usefulness of magnesium alanate as a\nhydrogen storage material.",
        "positive": "Studies of hot photoluminescence in plasmonically-coupled silicon via\n  variable energy excitation and temperature dependent spectroscopy: By coupling silicon nanowires (~150 nm diameter, 20 micron length) with an\n{\\Omega}-shaped plasmonic nanocavity we are able to generate broadband visible\nluminescence, which is induced by high-order hybrid nanocavity-surface plasmon\nmodes. The nature of this super-bandgap emission is explored via\nphotoluminescence spectroscopy studies performed with variable laser excitation\nenergies (1.959 eV to 2.708 eV) and finite difference time domain simulations.\nFurthermore, temperature-dependent photoluminescence spectroscopy shows that\nthe observed emission corresponds to radiative recombination of un-thermalized\n(hot) carriers as opposed to a Resonant Raman process."
    },
    {
        "anchor": "Translational boundaries as incipient ferrielectric domains in\n  antiferroelectric PbZrO3: In the archetypal antiferroelectric PbZrO3, antiparallel electric dipoles\ncancel each other, resulting in zero spontaneous polarisation at the\nmacroscopic level. Yet in actual hysteresis loops, the cancellation is rarely\nperfect and some remnant polarization is often observed, suggesting the\nmetastability of polar phases in this material. In this work, using\naberration-corrected scanning transmission electron microscopy methods on a\nPbZrO3 single crystal, we uncover the coexistence of the common\nantiferroelectric phase and a ferrielectric phase featuring an electric dipole\npattern of \"up down up\". This dipole arrangement, predicted by Aramberri et al.\n(2021) to be the ground state of PbZrO3 at 0K, appears at room temperature in\nthe form of translational boundaries that aggregate to form wider stripe\ndomains of the polar phase embedded within the antiferroelectric matrix.",
        "positive": "Blue luminescence of Au nanoclusters embedded in silica matrix: Photoluminescence study using the 325 nm He-Cd excitation is reported for the\nAu nanoclusters embedded in SiO2 matrix. Au clusters are grown by ion beam\nmixing with 100 KeV Ar+ irradiation on Au [40 nm]/SiO2 at various fluences and\nsubsequent annealing at high temperature. The blue bands above ~3 eV match\nclosely with reported values for colloidal Au nanoclusters and supported Au\nnanoislands. Radiative recombination of sp electrons above Fermi level to\noccupied d-band holes are assigned for observed luminescence peaks. Peaks at\n3.1 eV and 3.4 eV are correlated to energy gaps at the X- and L-symmetry\npoints, respectively, with possible involvement of relaxation mechanism. The\nblue shift of peak positions at 3.4 eV with decreasing cluster size is reported\nto be due to the compressive strain in small clusters. A first principle\ncalculation based on density functional theory using the full potential linear\naugmented plane wave plus local orbitals (FP-LAPW+LO) formalism with\ngeneralized gradient approximation (GGA) for the exchange correlation energy is\nused to estimate the band gaps at the X- and L-symmetry points by calculating\nthe band structures and joint density of states (JDOS) for different strain\nvalues in order to explain the blueshift of ~0.1 eV with decreasing cluster\nsize around L-symmetry point."
    },
    {
        "anchor": "Spin filtering through ferromagnetic BiMnO3 tunnel barriers: We report on experiments of spin filtering through ultra-thin single-crystal\nlayers of the insulating and ferromagnetic oxide BiMnO3 (BMO). The spin\npolarization of the electrons tunneling from a gold electrode through BMO is\nanalyzed with a counter-electrode of the half-metallic oxide La2/3Sr1/3MnO3\n(LSMO). At 3 K we find a 50% change of the tunnel resistances according to\nwhether the magnetizations of BMO and LSMO are parallel or opposite. This\neffect corresponds to a spin filtering effciency of up to 22%. Our results thus\nshow the potential of complex ferromagnetic insulating oxides for spin\nfiltering and injection.",
        "positive": "Simultaneous Nitrogen-Doping and Reduction of Graphene Oxide: We develop a simple chemical method to obtain bulk quantities of N-doped,\nreduced graphene oxide (GO) sheets through thermal annealing of GO in ammonia.\nX-ray photoelectron spectroscopy (XPS) study of GO sheets annealed at various\nreaction temperatures reveals that N-doping occurs at a temperature as low as\n300C, while the highest doping level of ~5% N is achieved at 500C. N-doping is\naccompanied by the reduction of GO with decreases in oxygen levels from ~28% in\nas-made GO down to ~2% in 1100C NH3 reacted GO. XPS analysis of the N binding\nconfigurations of doped GO finds pyridinic N in the doped samples, with\nincreased quaternary N (N that replaced the carbon atoms in the graphene plane)\nin GO annealed at higher temperatures (>900C). Oxygen groups in GO were found\nresponsible for reactions with NH3 and C-N bond formation. Pre-reduced GO with\nfewer oxygen groups by thermal annealing in H2 exhibits greatly reduced\nreactivity with NH3 and lower N-doping level. Electrical measurements of\nindividual GO sheet devices demonstrate that GO annealed in NH3 exhibits higher\nconductivity than those annealed in H2, suggesting more effective reduction of\nGO by annealing in NH3 than in H2, consistent with XPS data. The N-doped\nreduced GO shows clearly n-type electron doping behavior with Dirac point (DP)\nat negative gate voltages in three terminal devices. Our method could lead to\nthe synthesis of bulk amounts of N-doped, reduced GO sheets useful for various\npractical applications."
    },
    {
        "anchor": "Sparse random Fourier features based interatomic potentials for high\n  entropy alloys: Computational modeling of high entropy alloys (HEA) is challenging given the\nscalability issues of Density functional theory (DFT) and the non-availability\nof Interatomic potentials (IP) for molecular dynamics simulations (MD). This\nwork presents a computationally efficient IP for modeling complex elemental\ninteractions present in HEAs. The proposed random features-based IP can\naccurately model melting behaviour along with various process-related defects.\nThe disordering of atoms during the melting process was simulated. Predicted\natomic forces are within 0.08 eV/$\\unicode{xC5}$ of corresponding DFT forces.\nMD simulations predictions of mechanical and thermal properties are within\n7$\\%$ of the DFT values. High-temperature self-diffusion in the alloy system\nwas investigated using the IP. A novel sparse model is also proposed which\nreduces the computational cost by 94$\\%$ without compromising on the force\nprediction accuracy.",
        "positive": "Self-Supervised Generative Models for Crystal Structures: Drawing inspiration from the achievements of natural language processing, we\nadopt self-supervised learning and utilize an equivariant graph neural network\nto develop a unified platform designed for training generative models capable\nof generating crystal structures, as well as efficiently adapting to downstream\ntasks in material property prediction. To mitigate the challenge of\nincorporating large-scale assessment on the reliability of generated structures\ninto the training process, we utilize the generative adversarial network (GAN)\nwith its discriminator being a cost-effective evaluator for the generated\nstructures, resulting in notable improvements in model performance. We\ndemonstrate the utility of our model in finding the optimal crystal structure\nunder predefined conditions. Without reliance on properties acquired\nexperimentally or numerically, our model further displays its capability to\ncomprehend the mechanism of crystal structure formation through its ability to\ngrouping chemically similar elements. Therefore, this paper extends an\ninvitation to explore deeper into the scientific understanding of material\nstructures through generative models, offering a fresh perspective on\nbroadening the scope and efficacy of machine learning in material science."
    },
    {
        "anchor": "Extrinsic photonic crystals: Doped semiconductors are intrinsically homogeneous media. However, by\napplying an external magnetic field that has a spatially periodic variation,\ndoped semiconductors can behave extrinsically like conventional photonic\ncrystals. We show this possibility theoretically by calculating the photonic\nband structures of a doped semiconductor under an external, spatially periodic\nmagnetic field. Homogeneous media, behaving like conventional photonic crystals\nunder some external, spatially periodic fields, define a new kind of photonic\ncrystals: extrinsic photonic crystals. The proposed extrinsic photonic crystals\ncould not only extend the concept of photonic crystals but also lead to the\ncontrol of the dispersion and propagation of electromagnetic waves in a unique\nway: simply manipulating the externally applied fields.",
        "positive": "Electrical conductivity of multi-walled carbon nanotubes-SU8 epoxy\n  composites: We have characterized the electrical conductivity of the composite which\nconsists of multi-walled carbon nanotubes dispersed in SU8 epoxy resin.\nDepending on the processing conditions of the epoxy (ranging from\nnon-polymerized to cross-linked) we obtained tunneling and percolating-like\nregimes of the electrical conductivity of the composites. We interpret the\nobserved qualitative change of the conductivity behavior in terms of reduced\nseparation between the nanotubes induced by polymerization of the epoxy matrix."
    },
    {
        "anchor": "Applicability of molecular statics simulation to partial dislocations in\n  GaAs: The suitability of molecular statics (MS) simulations to model the structure\nof 90{\\deg} glide set partial dislocation cores in GaAs is analyzed. In the MS\nsimulations the atomic positions are iteratively relaxed by energy\nminimization, for which a Tersoff potential parametrization appropriate for\nnanostructures has been used. We show that for the Ga terminated partial the\nresulting bond lengths of the atoms in the dislocation core agree within 5-10%\nwith those of previous density functional theory studies, whereas a significant\ndiscrepancy appears in the case of the As terminated partial.",
        "positive": "Room temperature two-dimensional antiferromagnetic Weyl semimetal CrO\n  with giant spin-splitting and spin-momentum locked transport: Giant spin-splitting was recently predicted in collinear antiferromagnetic\nmaterials with a specific class of magnetic space group. In this work, we have\npredicted a two-dimensional (2D) antiferromagnetic Weyl semimetal (WS), CrO\nwith large spin-split band structure, spin-momentum locked transport properties\nand high N\\'eel temperature. It has two pairs of spin-polarized Weyl points at\nthe Fermi level. By manipulating the position of the Weyl points with strain,\nfour different antiferromagnetic spintronic states can be achieved: WSs with\ntwo spin-polarized transport channels (STCs), WSs with single STC,\nsemiconductors with two STCs, and semiconductors with single STC. Based on\nthese properties, a new avenue in spintronics with 2D collinear\nantiferromagnets is proposed."
    },
    {
        "anchor": "Superexchange-Driven Magnetoelectricity in Magnetic Vortices: We demonstrate that magnetic vortices in which spins are coupled to polar\nlattice distortions via superexchange exhibit an unusually large linear\nmagnetoelectric response. We show that the periodic arrays of vortices formed\nby frustrated spins on Kagom\\'e lattices provide a realization of this concept;\nour {\\it ab initio} calculations for such a model structure yield a\nmagnetoelectric coefficient that is 30 times larger than that of prototypical\nsingle phase magnetoelectrics. Finally, we identify the design rules required\nto obtain such a response in a practical material.",
        "positive": "Competing oxygen evolution reaction mechanisms revealed by high-speed\n  compressive Raman imaging: Transition metal oxides are state-of-the-art materials for catalysing the\noxygen evolution reaction (OER), whose slow kinetics currently limit the\nefficiency of water electrolysis. However, microscale physicochemical\nheterogeneity between particles, dynamic reactions both in the bulk and at the\nsurface, and an interplay between particle reactivity and electrolyte makes\nprobing the OER challenging. Here, we overcome these limitations by applying\nstate-of-the-art compressive Raman imaging to uncover competing bias-dependent\nmechanisms for the OER in a solid electrocatalyst, {\\alpha}-Li2IrO3. By\nspatially and temporally tracking changes in the in- and out-of-plane Ir-O\nstretching modes - identified by density functional theory calculations - we\nfollow catalytic activation and charge accumulation following ion exchange\nunder a variety of electrolytes, particle compositions and cycling conditions.\nWe extract velocities of phase fronts and demonstrate that at low\noverpotentials oxygen is evolved by the combination of an\nelectrochemical-chemical mechanism and a classical electrocatalytic adsorbate\nmechanism, whereas at high overpotentials only the latter occurs. These results\nprovide strategies to promote mechanisms for enhanced OER performances, and\nhighlight the power of compressive Raman imaging for low-cost, chemically\nspecific tracking of microscale reaction dynamics in a broad range of systems\nwhere ion and electron exchange can be coupled to structural changes, i.e.\ncatalysts, battery materials, memristors, etc."
    },
    {
        "anchor": "Dynamic Displacement Disorder of Cubic BaTiO$_3$: The three dimensional distribution of the X-ray diffuse scattering intensity\nof BaTiO$_3$ has been recorded in a synchrotron experiment and simultaneously\ncomputed using molecular dynamics simulations of a shell-model. Together these\nhave allowed the details of the disorder in paraelectric BaTiO$_3$ to be\nclarified. The narrow sheets of diffuse scattering, related to the famous\nanisotropic longitudinal correlations of Ti ions, are shown to be caused\nentirely by the overdamped anharmonic soft phonon branch. This finding\ndemonstrates that the occurrence of narrow sheets of diffuse scattering agrees\nwith a displacive picture of the cubic phase of this textbook ferroelectric\nmaterial.",
        "positive": "Origin of Metallic States at Heterointerface between Band Insulators\n  LaAlO$_3$ and SrTiO$_3$: We have studied the electronic structure at the heterointerface between the\nband insulators LaAlO$_3$ and SrTiO$_3$ using $in situ$ photoemission\nspectroscopy. Our experimental results clearly reveal the formation of a\nnotched structure on the SrTiO$_3$ side due to band bending at the metallic\nLaAlO$_3$/TiO$_2$-SrTiO$_3$ interface. The structure, however, is absent at the\ninsulating LaAlO$_3$/SrO-SrTiO$_3$ interface. The present results indicate that\nthe metallic states originate not from the charge transfer through the\ninterface on a short-range scale but from the accumulation of carriers on a\nlong-range scale."
    },
    {
        "anchor": "Nearly isotropic spin-pumping related Gilbert damping in\n  Pt/Ni$_{81}$Fe$_{19}$/Pt: A recent theory by Chen and Zhang [Phys. Rev. Lett. 114, 126602 (2015)]\npredicts strongly anisotropic damping due to interfacial spin-orbit coupling in\nultrathin magnetic films. Interfacial Gilbert-type relaxation, due to the spin\npumping effect, is predicted to be significantly larger for magnetization\noriented parallel to compared with perpendicular to the film plane. Here, we\nhave measured the anisotropy in the Pt/Ni$_{81}$Fe$_{19}$/Pt system via\nvariable-frequency, swept-field ferromagnetic resonance (FMR). We find a very\nsmall anisotropy of enhanced Gilbert damping with sign opposite to the\nprediction from the Rashba effect at the FM/Pt interface. The results are\ncontrary to the predicted anisotropy and suggest that a mechanism separate from\nRashba spin-orbit coupling causes the rapid onset of spin-current absorption in\nPt.",
        "positive": "An amplitude-phase (Ermakov-Lewis) approach for the Jackiw-Pi model of\n  bilayer graphene: In the context of bilayer graphene we use the simple gauge model of Jackiw\nand Pi to construct its numerical solutions in powers of the bias potential V\naccording to a general scheme due to Kravchenko. Next, using this numerical\nsolutions, we develop the Ermakov-Lewis approach for the same model. This leads\nus to numerical calculations of the Lewis-Riesenfeld phases that could be of\nforthcoming experimental interest for bilayer graphene. We also present a\ngeneralization of the Ioffe-Korsch nonlinear Darboux transformation"
    },
    {
        "anchor": "Electronic Structure of Dangling Bonds in Amorphous Silicon Studied via\n  a Density-Matrix Functional Method: A structural model of hydrogenated amorphous silicon containing an isolated\ndangling bond is used to investigate the effects of electron interactions on\nthe electronic level splittings, localization of charge and spin, and\nfluctuations in charge and spin. These properties are calculated with a\nrecently developed density-matrix correlation-energy functional applied to a\ngeneralized Anderson Hamiltonian, consisting of tight-binding one-electron\nterms parametrizing hydrogenated amorphous silicon plus a local interaction\nterm. The energy level splittings approach an asymptotic value for large values\nof the electron-interaction parameter U, and for physically relevant values of\nU are in the range 0.3-0.5 eV. The electron spin is highly localized on the\ncentral orbital of the dangling bond while the charge is spread over a larger\nregion surrounding the dangling bond site. These results are consistent with\nknown experimental data and previous density-functional calculations. The spin\nfluctuations are quite different from those obtained with unrestricted\nHartree-Fock theory.",
        "positive": "Spin Transport and Precession in Graphene measured by Nonlocal and\n  Three-Terminal Methods: We investigate the spin transport and precession in graphene by using the\nHanle effect in nonlocal and threeterminal measurement geometries. Identical\nspin lifetimes, spin diffusion lengths and spin polarizations are observed in\ngraphene devices for both techniques over a wide range of temperatures. The\nmagnitude of the spin signals is well explained by spin transport models. These\nobservations rules out any signal enhancements or additional scattering\nmechanisms at the interfaces for both geometries. This validates the\napplicability of both the measurement methods for graphene based spintronics\ndevices and their reliable extractions of spin parameters."
    },
    {
        "anchor": "GPTFF: A high-accuracy out-of-the-box universal AI force field for\n  arbitrary inorganic materials: This study introduces a novel AI force field, namely graph-based pre-trained\ntransformer force field (GPTFF), which can simulate arbitrary inorganic systems\nwith good precision and generalizability. Harnessing a large trove of the data\nand the attention mechanism of transformer algorithms, the model can accurately\npredict energy, atomic forces, and stress with Mean Absolute Error (MAE) values\nof 32 meV/atom, 71 meV/{\\AA}, and 0.365 GPa, respectively. The dataset used to\ntrain the model includes 37.8 million single-point energies, 11.7 billion force\npairs, and 340.2 million stresses. We also demonstrated that GPTFF can be\nuniversally used to simulate various physical systems, such as crystal\nstructure optimization, phase transition simulations, and mass transport.",
        "positive": "Electronic structure of the high and low pressure polymorphs of\n  MgSiN$_{2}$: We have performed density functional calculations on the group II-IV nitride\nMgSiN$_{2}$. At a pressure of about 20~GPa the ground state wurtzite derived\nMgSiN$_{2}$ structure (LP-MgSiN$_{2}$) transforms into a rock-salt derived\nstructure (HP-MgSiN$_{2}$) in agreement with previous theoretical and\nexperimental studies. Both phases are wide band gap semiconductors with\nindirect band gaps at equilibrium of 5.58 eV (LP-MgSiN$_{2}$) and 5.87 eV\n(HP-MgSiN$_{2}$), respectively. As the pressure increases, the band gaps become\nlarger for both phases, however, the band gap in LP-MgSiN$_{2}$ increases\nfaster than the gap in HP-MgSiN$_{2}$ and with a high enough pressure the band\ngap in LP-MgSiN$_{2}$ becomes larger than the band gap in HP-MgSiN$_{2}$."
    },
    {
        "anchor": "Magnetic Mn5Ge3 nanocrystals embedded in crystalline Ge: a\n  magnet/semiconductor hybrid synthesized by ion implantation: The integration of ferromagnetic Mn5Ge3 with the Ge matrix is promising for\nspin injection in a silicon-compatible geometry. In this paper, we report the\npreparation of magnetic Mn5Ge3 nanocrystals embedded inside the Ge matrix by Mn\nions implantation at elevated temperature. By X-ray diffraction and\ntransmission electron microscopy, we observe crystalline Mn5Ge3 with variable\nsize depending on the Mn ion fluence. The electronic structure of Mn in Mn5Ge3\nnanocrystals is 3d6 configuration, the same as in bulk Mn5Ge3. A large positive\nmagnetoresistance has been observed at low temperatures. It can be explained by\nthe conductivity inhomogeneity in the magnetic/semiconductor hybrid system.",
        "positive": "Phononic drumhead surface state in distorted kagome compound RhPb: RhPb was initially recognized as one of a CoSn-like compounds with $P6/mmm$\nsymmetry, containing an ideal kagome lattice of $d$-block atoms. However,\ntheoretical calculations predict the realization of the phonon soft mode which\nleads to the kagome lattice distortion and stabilization of the structure with\n$P\\bar{6}2m$ symmetry [A. Ptok et al., Phys. Rev. B 104, 054305 (2021)]. Here,\nwe present the single crystal x-ray diffraction results supporting this\nprediction. Furthermore, we discuss the main dynamical properties of RhPb with\n$P\\bar{6}2m$ symmetry. The bulk phononic dispersion curves contain several\nflattened bands, Dirac nodal lines, and triple degenerate Dirac points. As a\nconsequence, the phononic drumhead surface state is realized for the (100)\nsurface, terminated by the zigzag-like edge of Pb honeycomb sublattice."
    },
    {
        "anchor": "Magnetoelectricity at room temperature in Bi0.9-xTbxLa0.1FeO3 system: Magnetoelectric compounds with the general formula, Bi0.9-xRxLa0.1FeO3 (R\n=Gd, Tb, Dy, etc.), have been synthesized. These show the coexistence of\nferroelectricity and magnetism, possess high dielectric constant and exhibit\nmagnetoelectric coupling at room temperature. Such materials may be of great\nsignificance in basic as well as applied research.",
        "positive": "Learning macroscopic internal variables and history dependence from\n  microscopic models: This paper concerns the study of history dependent phenomena in heterogeneous\nmaterials in a two-scale setting where the material is specified at a fine\nmicroscopic scale of heterogeneities that is much smaller than the coarse\nmacroscopic scale of application. We specifically study a polycrystalline\nmedium where each grain is governed by crystal plasticity while the solid is\nsubjected to macroscopic dynamic loads. The theory of homogenization allows us\nto solve the macroscale problem directly with a constitutive relation that is\ndefined implicitly by the solution of the microscale problem. However, the\nhomogenization leads to a highly complex history dependence at the macroscale,\none that can be quite different from that at the microscale. In this paper, we\nexamine the use of machine-learning, and especially deep neural networks, to\nharness data generated by repeatedly solving the finer scale model to: (i) gain\ninsights into the history dependence and the macroscopic internal variables\nthat govern the overall response; and (ii) to create a computationally\nefficient surrogate of its solution operator, that can directly be used at the\ncoarser scale with no further modeling. We do so by introducing a recurrent\nneural operator (RNO), and show that: (i) the architecture and the learned\ninternal variables can provide insight into the physics of the macroscopic\nproblem; and (ii) that the RNO can provide multiscale, specifically FE2,\naccuracy at a cost comparable to a conventional empirical constitutive\nrelation."
    },
    {
        "anchor": "Interface Sharpening in Miscible and Isotopic Multilayers: Role of\n  Short-Circuit Diffusion: Atomic diffusion at nanometer length scale may differ significantly from bulk\ndiffusion, and may sometimes even exhibit counterintuitive behavior. In the\npresent work, taking Cu/Ni as a model system, a general phenomenon is reported\nwhich results in sharpening of interfaces upon thermal annealing, even in\nmiscible systems. Anomalous x-ray reflectivity from a Cu/Ni multilayer has been\nused to study the evolution of interfaces with thermal annealing. Annealing at\n423 K results in sharpening of interfaces by about 38%. This is the temperature\nat which no asymmetry exists in the inter-diffusivities of Ni and Cu. Thus, the\neffect is very general in nature, and is different from the one reported in the\nliterature, which requires a large asymmetry in the diffusivities of the two\nconstituents [Z. Erd\\'elyi et al., Science 306, 1913 (2004).]. General nature\nof the effect is conclusively demonstrated using isotopic multilayers of\n57Fe/naturalFe, in which evolution of isotopic interfaces has been observed\nusing nuclear resonance reflectivity. It is found that annealing at suitably\nlow temperature (e.g. 523 K) results in sharpening of the isotopic interfaces.\nSince chemically it is a single Fe layer, any effect associated with\nconcentration dependent diffusivity can be ruled out. The results can be\nunderstood in terms of fast diffusion along short-circuit paths like triple\njunctions, which results in an effective sharpening of the interfaces at\nrelatively low temperatures.",
        "positive": "The new neutron grating interferometer at the ANTARES beamline - Design,\n  Principle, and Applications -: Neutron grating interferometry is an advanced method in neutron imaging that\nallows the simultaneous recording of the transmission, the differential phase\nand the dark-field image. Especially the latter has recently received high\ninterest because of its unique contrast mechanism which marks ultra-small-angle\nneutron scattering within the sample. Hence, in neutron grating interferometry,\nan imaging contrast is generated by scattering of neutrons off micrometer-sized\ninhomogeneities. Although the scatterer cannot be resolved it leads to a\nmeasurable local decoherence of the beam. Here, a report is given on the design\nconsiderations, principles and applications of a new neutron grating\ninterferometer which has recently been implemented at the ANTARES beamline at\nthe Heinz Maier-Leibnitz Zentrum. Its highly flexible design allows to perform\nexperiments such as directional and quantitative dark-field imaging which\nprovide spatially resolved information on the anisotropy and shape of the\nmicrostructure of the sample. A comprehensive overview of the nGI principle is\ngiven, followed by theoretical considerations to optimize the setup performance\nfor different applications. Furthermore, an extensive characterization of the\nsetup is presented and its abilities are demonstrated on selected case studies:\n(i) dark-field imaging for material differentiation, (ii) directional\ndark-field imaging to mark and quantify micrometer anisotropies within the\nsample and (iii) quantitative dark-field imaging, providing additional size\ninformation on the sample's microstructure by probing its autocorrelation\nfunction."
    },
    {
        "anchor": "Dielectric and structural studies of ferroelectric phase evolution in\n  dipole pair substituted barium titanate ceramics: Ba{[Gax,Tax]Ti(1-2x)}O3 ceramics with x equal to 0, 0.0025, 0.005, 0.01,\n0.025 and 0.05 have been prepared by conventional solid-state reaction.\nStructural and dielectric characterization have been performed to investigate\nthe effect of dipole-pair substitution concentration on the macroscopic\ndielectric properties. Ba{[Gax,Tax]Ti(1-2x)}O3 evolves from a classic\nferroelectric to a diffuse phase transition (DPT) as x increases.\nBa{[Gax,Tax]Ti(1-2x)}O3 for x > or = 0.01 possesses diffuseness parameters\ncomparable to Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) and recently reported\n(Ba0.97Pr0.03)(Ti0.9425Ce0.05)O3 (BPTC), yet it lacks the frequency and\ntemperature dependence of Tm necessary to be a strictly defined relaxor\nferroelectric. Additionally, Ba{[Ga0.05,Ta0.05]Ti0.9}O3 possesses a relative\npermittivity, {\\epsilon}r, of 700+/-16% and dissipation factor less than 0.05\nat 10 kHz within the temperature range [-75{\\deg}C, 120{\\deg}C]. In comparison\nto BaTiO3, Ba{[Gax,Tax]Ti(1-2x)}O3 possesses enhanced electrical resistivity at\nand above room temperature. In-situ XRD, including Rietveld refinement, have\nbeen performed to determine the lattice parameter, coefficient of thermal\nexpansion and phase transition temperature (Tc) of each composition within the\ntemperature range [RT, 1000{\\deg}C], thus linking the dielectric properties\nwith the materials structure. These studies have been corroborated by\ntemperature dependent Raman spectroscopy to compare the Tc determined by\nelectrical and structural characterization. The properties of\nBa{[Gax,Tax]Ti(1-2x)}O3 are discussed in context with available models that\ndescribe donor and acceptor dopants spatially separated in the parent matrix,\ninter-relating lattice parameter, Curie temperature, and other material\nproperties",
        "positive": "Optical response of small closed-shell sodium clusters: Absorption spectra of closed-shell Na_2, Na_3+, Na_4, Na_5+, Na_6, Na_7+, and\nNa_8 clusters are calculated using a recently implemented conserving linear\nresponse method. In the framework of a quasiparticle approach, we determine\nelectron-hole correlations in the presence of an external field. The calculated\nresults are in excellent agreement with experimental spectra, and some possible\ncluster geometries that occur in experiments are analyzed. The position and the\nbroadening of the resonances in the spectra arise from a consistent treatment\nof the scattering and dephasing contributions in the linear response\ncalculation. Comparison between the experimental and the theoretical results\nyields information about the cluster geometry, which is not accessible\nexperimentally."
    },
    {
        "anchor": "Rolling up of graphite sheet: Energetics of shell formation: The energetics of transformation of a planar fragment of a graphite monolayer\ninto a spherical cluster is studied. The path considered is that a flat cluster\nrolls up into a segment of a spherical shell. The energy landscape of the\nprocess is presented. A simple model, formerly invented for calculating the\ncarbon nanocluster formation energy, is used to evaluate the energies of\nintermediate states. Although the spherical-shell closed cluster has the lowest\nenergy, curving of a plane fragment into a segment has an energy barrier. The\nbarrier height goes to zero for clusters with the number of atoms greater than\nsome $N_{\\rm th}$, for which the cluster size is found analytically.",
        "positive": "Effect of the addition of Al2O3, TiO2 and ZnO on the thermal, structural\n  and luminescence properties of Er3+-doped phosphate glasses: Er-doped phosphate glasses were fabricated by melt-quenching technique. The\nchanges in their thermal, structural and luminescence properties with the\naddition of Al2O3, TiO2 or ZnO were studied. Physical and thermal properties\nwere investigated through density measurement and differential thermal\nanalysis. Structural characterization was performed using the Raman and\nInfrared spectroscopy. In order to study the influence of the composition on\nthe luminescence properties of the glasses, the refractive index, the\nluminescence spectra and the lifetime values were measured. The results show\nthat with the addition of Al2O3 and TiO2 the phosphate network becomes more\nconnected increasing the glass transition temperature, whereas the addition of\nZnO does not show significant changes in the optical, thermal and structural\nproperties but it leads to a larger emission cross-section at 1540 nm as\ncompared to the other glasses. As the site of the Er3+ is not strongly affected\nby the change in the glass composition, we think that the emission properties\nof the glasses depend on the glass structure connectivity, which has an impact\non the Er3+ ions solubility."
    },
    {
        "anchor": "Floquet analysis of excitations in materials: Controlled excitation of materials can transiently induce changed or novel\nproperties with many fundamental and technological implications. Especially,\nthe concept of Floquet engineering, manipulation of the electronic structure\nvia dressing with external lasers, has attracted some recent interest. Here we\nreview the progress made in defining Floquet materials properties and give a\nspecial focus on their signatures in experimental observables as well as\nconsidering recent experiments realizing Floquet phases in solid state\nmaterials. We discuss how a wide range of experiments with non-equilibrium\nelectronic structure can be viewed by employing Floquet theory as an analysis\ntool providing a different view of excitations in solids.",
        "positive": "Field-created diverse quantizations in phosphorenes: Electronic properties of few-layer phosphorenes are investigated by the\ngeneralized tight-binding model. They are greatly diversified by the electric\nand magnetic fields ($E_z$ and $B_z$). The $E_z$-induced gap transition, Dirac\ncones, oscillatory bands and critical points are present in bilayer system, but\nabsent in monolayer one. The diverse magnetic quantization phenomena cover the\ncoexistent two subgroups of Landau levels, the uniform and non-uniform energy\nspacings, and the crossing and anti-crossing behaviors. Specifically, the\nwavefunctions exhibit the dramatic changes between the well-behaved and\nmulti-mode oscillations. The feature-rich energy spectra are reveled in density\nof states as .many special structures which could be verified from scanning\ntunneling spectroscopy."
    },
    {
        "anchor": "Anisotropic magnon-magnon coupling in synthetic antiferromagnets: The magnon-magnon coupling in synthetic antiferromagnets advances it as\nhybrid magnonic systems to explore the quantum information technologies. To\ninduce the magnon-magnon coupling, the parity symmetry between two\nmagnetization needs to be broken. Here we experimentally demonstrate a\nconvenient method to break the parity symmetry by the asymmetric thickness of\ntwo magnetic layers and thus introduce a magnon-magnon coupling in Ir-based\nsynthetic antiferromagnets CoFeB(10 nm)/Ir(tIr=0.6 nm, 1.2 nm)/CoFeB(13 nm).\nRemarkably, we find that the weakly uniaxial anisotropy field (~ 20 Oe) makes\nthe magnon-magnon coupling anisotropic. The coupling strength presented by a\ncharacteristic anticrossing gap varies in the range between 0.54 GHz and 0.90\nGHz for tIr =0.6 nm, and between nearly zero to 1.4 GHz for tIr = 1.2 nm,\nrespectively. Our results demonstrate a feasible way to induce the\nmagnon-magnon coupling by an asymmetric structure and tune the coupling\nstrength by varying the direction of in-plane magnetic field. The magnon-magnon\ncoupling in this highly tunable material system could open exciting\nperspectives for exploring quantum-mechanical coupling phenomena.",
        "positive": "Faster chiral versus collinear magnetic order recovery after optical\n  excitation revealed by femtosecond XUV scattering: While chiral spin structures stabilized by Dzyaloshinskii-Moriya interaction\n(DMI) are candidates as novel information carriers, their dynamics on the fs-ps\ntimescale is little known. Since with the bulk Heisenberg exchange and the\ninterfacial DMI two distinct exchange mechanisms are at play, the ultra-fast\ndynamics of the chiral order needs to be ascertained and compared to the\ndynamics of the conventional collinear order. Using an XUV free-electron laser\nwe determine the fs-ps temporal evolution of the chiral order in domain walls\nin a magnetic thin film sample by an IR pump - X-ray magnetic scattering probe\nexperiment. Upon demagnetisation we observe that the dichroic (CL-CR) signal\nconnected with the chiral order correlator $m_z m_x$ in the domain walls\nrecovers significantly faster than the (CL+CR) sum signal representing the\naverage collinear domain magnetisation $m_z^2 + m_x^2$. We explore possible\nexplanations based on spin structure dynamics and reduced transversal\nmagnetisation fluctuations inside the domain walls and find that the latter can\nexplain the experimental data leading to different dynamics for collinear\nmagnetic order and chiral magnetic order."
    },
    {
        "anchor": "Fermi level tuning and atomic ordering induced giant anomalous Nernst\n  effect in Co2MnAl1-xSix Heusler alloy: Co2MnAl has been predicted to have Weyl points near Fermi level which is\nexpected to give rise to exotic transverse transport properties such as large\nanomalous Hall(AHE) and Nernst effects(ANE) due to large Berry curvature. In\nthis study, the effect of Fermi level position and atomic ordering on AHE and\nANE in Co2MnAl1-xSix were studied systematically. The Co2MnAl film keeps\nB2-disordred structure regardless of annealing temperature, which results in\nmuch smaller anomalous Hall conductivity sigma_xy and transverse Peltier\ncoefficient sigma_xy than those calculated for L21-ordered Co2MnAl. Our newly\nperformed calculation of sigma_xy with taking B2 disordering into account well\nreproduces experimental result, thus it was concluded that Berry curvature\noriginating from Weyl points is largely reduced by B2 disordering. It was also\nrevealed Al substitution with Si shifts the position of Fermi level and\nimproves the L21-atomic ordering largely, leading to strong enhancement of\nsigma_xy, which also agreed with our theoretical calculation. The highest\nthermopower of ANE of 6.1uV, which is comparable to the recent reports for\nCo2MnGa, was observed for Co2MnAl0.63Si0.37 because of dominant contribution of\nsigma_xy. This study clearly shows the importance of both Fermi level tuning\nand high atomic ordering for obtaining the effect of topological feature in\nCo-based Heusler alloys on transverse transport properties.",
        "positive": "The MAterials Simulation Toolkit (MAST) for atomistic modeling of\n  defects and diffusion: The MAterials Simulation Toolkit (MAST) is a workflow manager and\npost-processing tool for ab initio defect and diffusion workflows. MAST\ncodifies research knowledge and best practices for such workflows, and allows\nfor the generation and management of easily modified and reproducible\nworkflows, where data is stored along with workflow information for data\nprovenance tracking. MAST is open-source and available for download (see PDF\nfor links)."
    },
    {
        "anchor": "Optical creation of vibrational intrinsic localized modes in anharmonic\n  lattices with realistic interatomic potentials: Using an efficient optimal control scheme to determine the exciting fields,\nwe theoretically demonstrate the optical creation of vibrational intrinsic\nlocalized modes (ILMs) in anharmonic perfect lattices with realistic\ninteratomic potentials. For systems with finite size, we show that ILMs can be\nexcited directly by applying a sequence of femtosecond visible laser pulses at\nTHz repetition rates. For periodic lattices, ILMs can be created indirectly via\ndecay of an unstable extended lattice mode which is excited optically either by\na sequence of pulses as described above or by a single picosecond far-infrared\nlaser pulse with linearly chirped frequency. In light of recent advances in\nexperimental laser pulse shaping capabilities, the approach is experimentally\npromising.",
        "positive": "Plasmon excitation by charged particles interacting with metal surfaces: Recent experiments (R. A. Baragiola and C. A. Dukes, Phys. Rev. Lett. {\\bf\n76}, 2547 (1996)) with slow ions incident at grazing angle on metal surfaces\nhave shown that bulk plasmons are excited under conditions where the ions do\nnot penetrate the surface, contrary to the usual statement that probes exterior\nto an electron gas do not couple to the bulk plasmon. We here use the quantized\nhydrodynamic model of the bounded electron gas to derive an explicit expression\nfor the probability of bulk plasmon excitation by external charged particles\nmoving parallel to the surface. Our results indicate that for each ${\\bf q}$\n(the surface plasmon wave vector) there exists a continuum of bulk plasmon\nexcitations, which we also observe within the semi-classical infinite-barrier\n(SCIB) model of the surface."
    },
    {
        "anchor": "Experimental magnetic form factors in Co3V2O8: A combined study of ab\n  initio calculations, magnetic Compton scattering and polarized neutron\n  diffraction: We present a combination of ab initio calculations, magnetic Compton\nscattering and polarized neutron experiments, which elucidate the density\ndistribution of unpaired electrons in the kagome staircase system Co3V2O8. Ab\ninitio wave functions were used to calculate the spin densities in real and\nmomentum space, which show good agreement with the respective experiments. It\nhas been found that the spin polarized orbitals are equally distributed between\nthe t2g and the eg levels for the spine (s) Co ions, while the eg orbitals of\nthe cross-tie (c) Co ions only represent 30% of the atomic spin density.\nFurthermore, the results reveal that the magnetic moments of the cross-tie Co\nions, which are significantly smaller than those of the spine Co ions in the\nzero-field ferromagnetic structure, do not saturate by applying an external\nmagnetic field of 2 T along the easy axis a, but that the increasing bulk\nmagnetization originates from induced magnetic moments on the O and V sites.\nThe refined individual magnetic moments are mu(Co_c)=1.54(4) mu_B,\nmu(Co_s)=2.87(3) mu_B, mu(V)=0.41(4) mu_B, mu(O1)=0.05(5) mu_B, mu(O2)=0.35(5)\nmu_B, and; mu(O3)=0.36(5) mu_B combining to the same macroscopic magnetization\nvalue, which was previously only attributed to the Co ions.",
        "positive": "Electrocaloric effect in KH$_2$PO$_4$ family crystals: The proton ordering model for the KH$_{2}$PO$_{4}$ type ferroelectrics is\nmodified by taking into account the dependence of the effective dipole moments\non the proton ordering parameter. Within the four-particle cluster\napproximation we calculate the crystal polarization and explore the\nelectrocaloric effect. Smearing of the ferroelectric phase transition by a\nlongitudinal electric field is described. A good agreement with experiment is\nobtained."
    },
    {
        "anchor": "Temperature rise in shear bands in a simulated metallic glass: Temperature rise ($\\Delta T$) associated with shear-banding of metallic\nglasses is of great importance for their performance. However, experimental\nmeasurement of $\\Delta T$ is difficult due to temporal and spatial localization\nof shear bands and, as a result, our understanding of the mechanism of $\\Delta\nT$ is limited. Here, based on molecular dynamics simulations we observe a\nspectrum of $\\Delta T$, which depends on both sample size and strain rate, in\nthe shear bands of CuZr metallic glass under tension. More importantly, we find\nthat the maximum sliding velocity of the shear bands correlates linearly with\nthe corresponding $\\Delta T$, ranging from $\\sim$25 K up to near the melting\npoint for the samples studied. Taking heat diffusion into account, we expect\n$\\Delta T$ to be lower than 25 K for the lower end of sliding velocity. At high\ntemperature, shear band bifurcation and/or multiplication can occur as a\nnegative feedback mechanism that prevents temperature rising well above the\nmelting point.",
        "positive": "Effects of nonlocal plasmons in gapped graphene micro-ribbon array and\n  2DEG on near-field electromagnetic response in the deep-subwavelength regime: A self-consistent theory involving Maxwell equations and a density-matrix\nlinear-response theory is solved for an electromagnetically-coupled doped\ngraphene micro-ribbon array and a quantum-well electron gas sitting at an\ninterface between a half-space of air and another half-space of a doped\nsemiconductor substrate which supports a surface-plasmon mode in our system.\nThe coupling between a spatially-modulated total electromagnetic field and the\nelectron dynamics in a Dirac-cone of a graphene ribbon, as well as the coupling\nof the far-field specular and near-field higher-order diffraction modes, are\nincluded in the derived electron optical-response function. Full analytical\nexpressions are obtained with non-locality for the optical-response functions\nof a two-dimensional electron gas and a graphene layer with an induced bandgap,\nand are employed in our numerical calculations beyond the long-wavelength limit\n(Drude model). Both the near-field transmissivity and reflectivity spectra, as\nwell as their dependence on different configurations of our system and on the\narray period, ribbon width, graphene chemical potential of quantum-well\nelectron gas and bandgap in graphene, are studied. Moreover, the transmitted\nE-field intensity distribution is calculated to demonstrate its connection to\nthe mixing of specular and diffraction modes of the total electromagnetic\nfield. An externally-tunable electromagnetic coupling among the surface,\nconventional electron-gas and massless graphene intraband plasmon excitations\nis discovered and explained. Furthermore, a comparison is made between the\ndependence of the graphene-plasmon energy on the ribbon width and chemical\npotential in this paper and the recent experimental observation given by Ju, et\nal., [Nature Nanotechnology, 6, 630 (2011)] for a graphene micro-ribbon array\nin the terahertz-frequency range."
    },
    {
        "anchor": "Processing of nanostructured bulk Fe-Cr alloys by severe plastic\n  deformation: The processing of binary alloys consisting of ferromagnetic Fe and\nantiferromagnetic Cr by severe plastic deformation (SPD) with different\nchemical compositions has been investigated. Although the phase diagram\nexhibits a large gap in the thermodynamical equilibrium at lower temperatures,\nit is shown that techniques based on SPD help to overcome common processing\nlimits. Different processing routes including initial ball milling (BM) and arc\nmelting (AM) and a concatenation with annealing treatments prior to\nhigh-pressure torsion (HPT) deformation are compared in this work.\nInvestigation of the deformed microstructures by electron microscopy and\nsynchrotron X-ray diffraction reveal homogeneous, nanocrystalline\nmicrostructures for HPT deformed AM alloys. HPT deformation of powder blends\nand BM powders leads to an exorbitant increase in hardness or an unusual fast\nformation of a $\\sigma$-phase and therefore impede successful processing.",
        "positive": "The properties and the structure of colloid agregates of the silver\n  besilcate Ag6Si2O7 in water medium: The paper describes the investigation of the properties of silver besilicate\nsalt colloids in water medium. Ag6Si2O7 was obtained in a soft conditions, in\nwater medium, at temperatures and pressure close to room ones. The morphology\nand crystallinity of matter under investigations appear to depend on the growth\nconditions. Slow growth resulted in quasi-crystalline yellowish whiskers, while\nhigh concentration of precursors led to fast formation of the quasi-amorphous\naggregates. The elemental constitution of object under study was determined\nwith the help of Comebax-INCA set-up, and was then proved by chemical analysis.\nThe ratio of elements was close to Ag6Si2O7, and depended a little whether the\nsample was taken from the sediments of reaction or from dried residue of a\nliquid medium. The experiments in Raman technique revile several\nwell-resolvable bands in whisker-like samples, but only few of them were able\nto detect in quasi-amorphous material. In the last case the bands were broader,\nbut the positions of weak broad bands were close to the positions of\ncorresponding bands in whiskers. We can suggest, that the bands, common in two\nformer cases, are due to oscillation in bepyramidal molecules of Ag6Si2O7, and\nthe bands, seen only at whiskers, are due to long-rang order. The very special\npeculiarity was observed under chemical test with hydrochloric acid. The white\nflakes sedimentation appeared after addition of NaCl but do not appeared when\nHCl was added. This result can be explained if to assume the existence of\nsilicon acid shell around the colloidal particles of silver besilicate. The\nmodel of silicon acid shell around colloids was proved by high resolution\nelectron microscopy."
    },
    {
        "anchor": "Studies of two-dimensional material resistive random-access memory by\n  kinetic Monte Carlo simulations: Resistive memory based on 2D WS2, MoS2, and h-BN materials has been studied,\nincluding experiments and simulations. The influences with different active\nlayer thicknesses have been discussed, including experiments and simulations.\nThe thickness with the best On/Off ratio is also found for the 2D RRAM. This\nwork reveals fundamental differences between a 2D RRAM and a conventional oxide\nRRAM. Furthermore, from the physical parameters extracted with the KMC model,\nthe 2D materials have a lower diffusion activation energy from the vertical\ndirection, where a smaller bias voltage and a shorter switching time can be\nachieved. It was also found the diffusion activation energy from the CVD-grown\nsample is much lower than the mechanical exfoliated sample. The result shows\nMoS2 has the fastest switching speed among three 2D materials.",
        "positive": "Interface combinatorial pulsed laser deposition to enhance\n  heterostructures functional properties: In this chapter we will describe a new development of combinatorial pulsed\nlaser deposition (CPLD) which targets the exploration of interface libraries.\nThe idea is to modulate continuously the composition of interfaces on a few\natomic layers in order to alter their functional properties. This unique\ncombinatorial synthesis of interfaces is possible due to very specific PLD\ncharacteristics. The first one is its well-known ability for complex oxide\nstoichiometry transfer from the target to the film. The second one is the layer\nby layer control of thin film growth at the atomic level using in-situ RHEED\ncharacterization. The third one relates to the directionality of the ablated\nplume which allows for selective area deposition on the substrate using a\nmobile shadow-mask. However PLD also has some limitations and important PLD\naspects to be considered for reliable CPLD are reviewed. Multiple examples\nregarding the control of interface magnetism in magnetic tunnel junctions and\nenergy band and Schottky barrier height tuning in ferroelectric tunable\ncapacitors are presented."
    },
    {
        "anchor": "The unusual temperature dependence of the Eu$^{2+}$ fluorescence\n  lifetime in CaF$_2$ crystals: Fluorescence lifetimes of Eu$^{2+}$ doped in CaF$_2$ are measured at various\ntemperatures between 4K and 450K. The lifetime increases with between 100K and\n300K, in contrast to the usual lifetime-temperature dependence. At higher or\nlower temperatures the lifetime decreases with increasing temperature. The\nphenomenon is explained by simulation of the energy levels and lifetimes of\nlow-lying $4f^65d$ states involved in the fluorescence.",
        "positive": "Enhanced elastic stability of a topologically disordered crystalline\n  metal--organic framework: By virtue of their open network structures and low densities, metal--organic\nframeworks (MOFs) are soft materials that exhibit elastic instabilities at low\napplied stresses. The conventional strategy for improving elastic stability is\nto increase the connectivity of the underlying MOF network, which necessarily\nincreases material density and reduces porosity. Here we demonstrate an\nalternative paradigm, whereby elastic stability is enhanced in a MOF with an\naperiodic network topology. We use a combination of variable-pressure\nsingle-crystal X-ray diffraction measurements and coarse-grained\nlattice-dynamical calculations to interrogate the high-pressure behaviour of\nthe topologically aperiodic system TRUMOF-1, which we compare against that of\nits ordered congener MOF-5. We show that the topology of the former quenches\nthe elastic instability responsible for pressure-induced framework collapse in\nthe latter, much as irregularity in the shapes and sizes of stones acts to\nprevent cooperative mechanical failure in drystone walls. Our results establish\naperiodicity as a counterintuitive design motif in engineering the mechanical\nproperties of framework structures, relevant to MOFs and larger-scale\narchitectures alike."
    },
    {
        "anchor": "Planar array of self-assembled Ga$_{x}$Fe$_{4-x}$N nanocrystals in GaN:\n  Magnetic anisotropy determined via ferromagnetic resonance: The magnetic anisotropy of a planar array of Ga$_{x}$Fe$_{4-x}$N nanocrystals\n(NCs) embedded in a GaN host is studied by ferromagnetic resonance. X-ray\ndiffraction and transmission electron microscopy are employed to determine the\nphase and distribution of the nanocrystals. The magnetic anisotropy is found to\nbe primarily uniaxial with the hard axis normal to the NCs plane and to have a\ncomparably weak in-plane hexagonal symmetry. The origin of the magnetic\nanisotropy is discussed taking into consideration the morphology of the\nnanocrystals, the epitaxial relations, strain effects and magnetic coupling\nbetween the NCs.",
        "positive": "Elastic Properties of Functionalized Carbon Nanotubes: We study the effects of covalent functionalization of single wall carbon\nnanotubes (CNT) on their elastic properties. We consider simple organic\nmolecules -NH, -NH2, -CH2, -CH3, -OH attached to CNTs' surface at various\ndensities. The studies are based on the first principles calculations in the\nframework of density functional theory. We have determined the changes in the\ngeometry and the elastic moduli of the functionalized CNTs as a function of the\ndensity of adsorbed molecules. It turns out that elastic moduli diminish with\nincreasing concentration of adsorbands, however, the functionalized CNTs remain\nstrong enough to be suitable for reinforcement of composites. The strongest\neffect is observed for CNTs functionalized with -CH2 radical, where the Young's\nmodulus of the functionalized system is by 30% smaller than in the pristine\nCNTs."
    },
    {
        "anchor": "A General Framework for Liquid Marbles: Liquid marbles refer to liquid droplets that are covered with a layer of\nnon-wetting particles. They are observed in nature and have practical\nsignificance. However, a generalized framework for analyzing liquid marbles as\nthey inflate or deflate is unavailable. The present study fills this gap by\ndeveloping an analytical framework based on liquid-particle and\nparticle-particle interactions. We demonstrate that the potential final states\nof evaporating liquid marbles are characterized by one of the following: (I)\nconstant surface area, (II) particle ejection, or (III) multilayering. Based on\nthese insights, a single-parameter evaporation model for liquid marbles is\ndeveloped. Model predictions are in excellent agreement with experimental\nevaporation data for water liquid marbles of particle sizes ranging from 7\nnanometers to 300 micrometers (over four orders of magnitude) and chemical\ncompositions ranging from hydrophilic to superhydrophobic. These findings lay\nthe groundwork for the rational design of liquid marble applications.",
        "positive": "Continuous Tuning the Magnitude and Direction of Spin-Orbit Torque Using\n  Bilayer Heavy Metals: Spin-orbit torques (SOTs) have opened a new path to switch the magnetization\nin perpendicularly magnetized films and are of great interest due to their\npotential applications in novel data storage technology, such as the magnetic\nrandom access memory (MRAM). The effective manipulation of SOT has thus become\nan important step towards these applications. Here, current induced spin-orbit\neffective fields and magnetization switching are investigated in\nPt/Ta/CoFeB/MgO structures with bilayer heavy metals. With a fixed thickness (1\nnm) of the Ta layer, the magnitude and sign of current induced spin-orbit\neffective fields can be continuously tuned by changing the Pt layer thickness,\nconsistent with the current induced magnetization switching data. The ratio of\nlongitudinal to transverse spin-orbit effective fields is found to be\ndetermined by the Ta/CoFeB interface and can be continuously tuned by changing\nthe Pt layer thickness. The Dzyaloshinskii-Moriya interaction (DMI) is found to\nbe weak and shows an insignificant variation with the Pt thickness. The results\ndemonstrate an effective method to tune SOTs utilizing bilayer heavy metals\nwithout affecting the DMI, a desirable feature which will be useful for the\ndesign of SOT-based devices."
    },
    {
        "anchor": "Electric field dependent thermal conductivity of relaxor ferroelectric\n  PMN-33PT through changes in the phonon spectrum: In ferroelectric materials, an applied electric field has been shown to\nchange the phonon dispersion relation sufficiently to alter the lattice thermal\nconductivity, opening the theoretical possibility that a heat gradient could\ndrive a polarization flux, and technologically, also opening a new avenue\ntoward all solid-state heat switching. In this report, we confirm\nexperimentally the validity of the theory originally developed for Pb(Zr,Ti)O_3\n(PZT) on the ferroelectric relaxor 0.66Pb[Mg_(1/3)Nb_(2/3)]O_3-0.33PbTiO_3\n(PMN-33PT). In the theory, the relative change in sound velocity and thermal\nconductivity with applied electric field relates to the piezoelectric\ncoefficients (d_33 and d_31) and the Gr\\\"uneisen parameter ({\\gamma}). The\ntheory predicts that in PMN-33PT the effect should be an order of magnitude\nlarger, and of opposite sign as in PZT; this is confirmed here. The effect is\nmeasured on samples that undergo multiple field sweep cycles and pass through 2\nphase transitions. The thermal conductivity changes are closely linked to\nvariations in the piezoelectric coefficients. A null experiment on paraelectric\nSrTiO_3 confirms the link between ferroelectricity and phonon spectrum changes.\nChanges in heat conduction as large as 10% can be achieved over large\ntemperature ranges, opening a possibility for practical heat switches based on\nphonon spectrum changes.",
        "positive": "Structural and magnetic properties of Fe-Co-C alloys with tetragonal\n  deformation: a first-principle study: Fe-Co alloys with induced tetragonal strain are promising materials for\nrare-earth-free permanent magnets. However, as ultrathin-film studies have\nshown, tetragonal Fe-Co structures tend to a rapid relaxation toward a cubic\nstructure as the thickness of the deposited film increases. One of the main\nmethods of inducing the stable strain in the bulk material is interstitial\ndoping with small atoms, like B, C, or N. In this work, we present a full\nconfiguration space analysis in density functional theory approach for\n(Fe$_{1-x}$Co$_x$)$_{16}$C supercells with a single C impurity in one of the\noctahedral interstitial positions and for the full range of Co concentrations\n$x$. We discuss all assumptions and considerations leading to calculated\nlattice parameters, mixing enthalpies, magnetic moments, and averaged\nmagnetocrystalline anisotropy energies (MAE). We present a comprehensive\nqualitative analysis of the structural and magnetic properties' dependence on\nshort- and long-range ordering parameters. We analyzed all unique Fe/Co atoms\noccupancies at all stoichiometric concentrations possible in 2x2x2 supercell\nbased on 2-atom tetragonal representation. We rely on the thermodynamic\naveraging method and large sample count to obtain accurate MAE values. We\nreevaluate several chemical disorder approximation methods, including effective\nmedium methods (virtual crystal approximation and coherent potential\napproximation) and special quasirandom structures method applied to Fe-Co-based\nalloys. We observe a structural phase transition from the body-centered\ntetragonal structure above 70% Co concentration and confirm the structural\nstability of Fe-Co-C alloys in the tetragonal range. We show the presence of a\nbroad MAE maximum of around 50% Co concentration and notably high MAE values\nfor Co content $x$ as low as 25%. In addition, we show a positive correlation\nbetween MAE and mixing enthalpy."
    },
    {
        "anchor": "Characterization of Surface Deformation Behavior, Mechanical and\n  Physical Properties of Modified-clay Bricks: The demand for building material is ever increasing owing to population\ngrowth. Compacted clay bricks are an important integral building material\nespecially for low cost durable and affordable housing segment. This is a\nvalued building material since its properties can be modified to suit various\nloading conditions. In this paper, the mechanical and physical properties of\nclay bricks modified with varying proportions of sawdust and polystyrene are\ndetermined. Increment of non-clay material proportion in the modified-clay\nbricks increases their porosity and water absorbency while their bulk\ndensities, compressive and flexural strengths decreases. The use is made of\nParticle Image Velocimetry (PIV) method to assess the surface deformation\nbehavior of the modified-clay bricks under uniaxial compressive loading. The\ndistribution of surface deformation as assessed through PIV method is\nrelatively uniform in pure-clay bricks while modified-clay bricks indicates a\nnon-uniform deformation localized near the loading point at low strains. The\nstrain distribution progressively spread out in the modifiedclay brick as the\nfailure point is approached.",
        "positive": "The Paracrystalline Nature of Lattice Distortion in a High Entropy Alloy: Severe lattice distortion is suggested for high entropy alloys (HEAs),\nhowever, evidence for such effect so far is lacking, and the nature of\ndistortion is yet to be understood. Here, we reveal the distortion in an fcc\nHEA, Al0.1CrFeCoNi, by direct imaging using electron nanodiffraction.\nInformation about crystal symmetry, lattice strain and atomic distortion are\ndata-mined and mapped from many (~10^4) diffraction patterns. Application to\nthe HEA reveals two embodiments of distortion, nm-sized mosaic blocks of\nparacrystals and strained nano-clusters. Their interaction gives rise to\nfractal strain field across nanoscopic to mesoscopic scales. As lattice\ndistortion impedes dislocation motion and contributes to strengthening, results\nhere thus provide critical insights about the complex nature of distortion in a\nHEA."
    },
    {
        "anchor": "Expeditious computation of nonlinear optical properties of arbitrary\n  order with native electronic interactions in the time domain: We adapted a recently proposed framework to characterize the optical response\nof interacting electrons in solids in order to expedite its computation without\ncompromise in accuracy at the microscopic level. Our formulation is based on\nreliable parameterizations of Hamiltonians and Coulomb interactions, which\nallows economy and flexibility in obtaining response functions. It is suited to\ncomputing the optical response to fields of arbitrary temporal shape and\nstrength, to arbitrary order in the field, and natively accounts for excitonic\neffects. We demonstrate the approach by computing the frequency-dependent\nsusceptibilities of MoS2 and hexagonal BN monolayers up to the third-harmonic.\nGrounded on a generic non-equilibrium many-body perturbation theory, this\nframework allows extensions to handle generic interaction models or to describe\nelectronic processes taking place at ultrafast time scales.",
        "positive": "Poisson's ratio in composite elastic media with rigid rods: We study the elastic response of composites of rods embedded in elastic\nmedia. We calculate the micro-mechanical response functions, and bulk elastic\nconstants as functions of rod density. We find two fixed points for Poisson's\nratio with respect to the addition of rods in 3D composites: there is an\nunstable fixed point for Poisson's ratio=1/2 (an incompressible system) and a\nstable fixed point for Poisson's ratio=1/4 (a compressible system). We also\nderive an approximate expression for the elastic constants for arbitrary rod\ndensity that yields exact results for both low and high density. These results\nmay help to explain recent experiments [Physical Review Letters 102, 188303\n(2009)] that reported compressibility for composites of microtubules in F-actin\nnetworks."
    },
    {
        "anchor": "Individual skyrmion manipulation by local magnetic field gradients: Magnetic skyrmions are topologically protected spin textures, stabilised in\nsystems with strong Dzyaloshinskii-Moriya interaction (DMI). Several studies\nhave shown that electrical currents can move skyrmions efficiently through\nspin-orbit torques. While promising for technological applications,\ncurrent-driven skyrmion motion is intrinsically collective and accompanied by\nundesired heating effects. Here we demonstrate a new approach to control\nindividual skyrmion positions precisely, which relies on the magnetic\ninteraction between sample and a magnetic force microscopy (MFM) probe. We\ninvestigate perpendicularly magnetised X/CoFeB/MgO multilayers, where for X = W\nor Pt the DMI is sufficiently strong to allow for skyrmion nucleation in an\napplied field. We show that these skyrmions can be manipulated individually\nthrough the local field gradient generated by the scanning MFM probe with an\nunprecedented level of accuracy. Furthermore, we show that the probe stray\nfield can assist skyrmion nucleation. Our proof-of-concepts results offer\ncurrent-free paradigms to efficient individual skyrmion control.",
        "positive": "Electronic and optical properties of Cadmium fluoride: the role of\n  many-body effects: Electronic excitations and optical spectra of $CdF_{2}$ are calculated up to\nultraviolet employing state-of-the-art techniques based on density functional\ntheory and many-body perturbation theory. The GW scheme proposed by Hedin has\nbeen used for the electronic self-energy to calculate single-particle\nexcitation properties as energy bands and densities of states. For optical\nproperties many-body effects, treated within the Bethe-Salpeter equation\nframework, turn out to be crucial. A bound exciton located about 1 eV below the\nquasiparticle gap is predicted. Within the present scheme the optical\nabsorption spectra and other optical functions show an excellent agreement with\nexperimental data. Moreover, we tested different schemes to obtain the best\nagreement with experimental data. Among the several schemes, we suggest a\nself-consistent quasiparticle energy scheme."
    },
    {
        "anchor": "Investigating representation schemes for surrogate modeling of High\n  Entropy Alloys: The design of new High Entropy Alloys that can achieve exceptional mechanical\nproperties is presently of great interest to the materials science community.\nHowever, due to the difficulty of designing these alloys using traditional\nmethods, machine learning has recently emerged as an essential tool.\nParticularly, the screening of candidate alloy compositions using surrogate\nmodels has become a mainstay of materials design in recent years. Many of these\nmodels use the atomic fractions of the alloying elements as inputs. However,\nthere are many possible representation schemes for encoding alloy compositions,\nincluding both unstructured and structured variants. As the input features play\na critical role in determining surrogate model performance, we have\nsystematically compared these representation schemes on the basis of their\nperformance in single-task deep learning models and in transfer learning\nscenarios. The results from these tests indicate that compared to the\nunstructured and randomly ordered schemes, chemically meaningful arrangements\nof elements within spatial representation schemes generally lead to better\nmodels. However, we also observed that tree-based models using only the atomic\nfractions as input were able to outperform these models in transfer learning.",
        "positive": "Lifetime and surface-to-bulk scattering off vacancies of the topological\n  surface state in the three-dimensional strong topological insulators Bi2Te3\n  and Bi2Se3: We analyze the finite lifetimes of the topologically protected electrons in\nthe surface state of Bi2Te3 and Bi2Se3 due to elastic scattering off surface\nvacancies and as a function of energy. The scattering rates are decomposed into\nsurface-to-surface and surface-to-bulk contributions, giving us new fundamental\ninsights into the scattering properties of the topological surface states\n(TSS). If the number of possible final bulk states is much larger than the\nnumber of final surface states, then the surface-to-bulk contribution is of\nimportance, otherwise the surface-to-surface contribution dominates.\nAdditionally, we find defect resonances that have a significant impact on the\nscattering properties of the TSS. They can strongly change the lifetime of the\nsurface state to vary between tens of fs to ps at surface defect concentrations\nof 1 at%."
    },
    {
        "anchor": "Voltage controlled spin injection in a (Ga,Mn)As/(Al,Ga)As Zener diode: The spin polarization of the electron current in a\np-(Ga,Mn)As-n-(Al,Ga)As-Zener tunnel diode, which is embedded in a\nlight-emitting diode, has been studied theoretically. A series of\nself-consistent simulations determines the charge distribution, the band\nbending, and the current-voltage characteristics for the entire structure. An\nempirical tight-binding model, together with the Landauer- Buttiker theory of\ncoherent transport has been developed to study the current spin polarization.\nThis dual approach allows to explain the experimentally observed high magnitude\nand strong bias dependence of the current spin polarization.",
        "positive": "Exfoliation of Two-Dimensional Nanosheets of Metal Diborides: The metal diborides are a class of ceramic materials with crystal structures\nconsisting of hexagonal sheets of boron atoms alternating with planes of metal\natoms held together with mixed character ionic/covalent bonds. Many of the\nmetal diborides are ultrahigh temperature ceramics like HfB$_2$, TaB$_2$, and\nZrB$_2$, which have melting points above 3000$^\\circ$C, high mechanical\nhardness and strength at high temperatures, and high chemical resistance, while\nMgB$_2$ is a superconductor with a transition temperature of 39 K. Here we\ndemonstrate that this diverse family of non-van der Waals materials can be\nprocessed into stable dispersions of two-dimensional (2D) nanosheets using\nultrasonication-assisted exfoliation. We generate 2D nanosheets of the metal\ndiborides AlB$_2$, CrB$_2$, HfB$_2$, MgB$_2$, NbB$_2$, TaB$_2$, TiB$_2$, and\nZrB$_2$, and use electron and scanning probe microscopies to characterize their\nstructures, morphologies, and compositions. The exfoliated layers span up to\nmicrometers in lateral dimension and reach thicknesses down to 2-3 nm, while\nretaining their hexagonal atomic structure and chemical composition. We exploit\nthe convenient solution-phase dispersions of exfoliated CrB$_2$ nanosheets to\nincorporate them directly into polymer composites. In contrast to the hard and\nbrittle bulk CrB$_2$, we find that CrB$_2$ nanocomposites remain very flexible\nand simultaneously provide increases in the elastic modulus and the ultimate\ntensile strength of the polymer. The successful liquid-phase production of 2D\nmetal diborides enables their processing using scalable low-temperature\nsolution-phase methods, extending their use to previously unexplored\napplications, and reveals a new family of non-van der Waals materials that can\nbe efficiently exfoliated into 2D forms."
    },
    {
        "anchor": "Quantum Computation for Predicting Electron and Phonon Properties of\n  Solids: Quantum chemistry is one of the most promising near-term applications of\nquantum computers. Quantum algorithms such as variational quantum eigen solver\n(VQE) and variational quantum deflation (VQD) algorithms have been mainly\napplied for molecular systems and there is a need to implement such methods for\nperiodic solids. Using Wannier tight-binding Hamiltonian (WTBH) approaches, we\ndemonstrate the application of VQE and VQD to accurately predict both\nelectronic and phonon bandstructure properties of several elemental as well as\nmulti-component solid-state materials. We apply VQE-VQD calculations for 307\nspin-orbit coupling based electronic WTBHs and 933 finite-difference based\nphonon WTBHs. Also, we discuss a workflow for using VQD with lattice Greens\nfunction that can be used for solving dynamical mean-field theory problems. The\nWTBH model solvers can be used for testing other quantum algorithms and models\nalso.",
        "positive": "Selenium and the role of defects for photovoltaic applications: We present first principles calculations of the electronic properties of\ntrigonal selenium with emphasis on photovoltaic applications. The band gap and\noptical absorption spectrum of pristine selenium is calculated from many-body\nperturbation theory yielding excellent agreement with experiments. We then\ninvestigate the role of intrinsic as well as extrinsic defects and estimate the\nequilibrium concentrations resulting from realistic synthesis conditions. The\nintrinsic defects are dominated by vacancies and we show that these do not\nresult in significant non-radiative recombination. The charge balance remains\ndominated by vacancies when extrinsic defects are included, but these may give\nrise to sizable non-radiative recombination rates, which could severely limit\nthe performance of selenium based solar cells. Our results thus imply that the\npollution by external elements is a decisive factor for the photovoltaic\nefficiency, which will be of crucial importance when considering synthesis\nconditions for any type of device engineering."
    },
    {
        "anchor": "Inverse design of glass structure with deep graph neural networks: Directly manipulating the atomic structure to achieve a specific property is\na long pursuit in the field of materials. However, hindered by the disordered,\nnon-prototypical glass structure and the complex interplay between structure\nand property, such inverse design is dauntingly hard for glasses. Here,\ncombining two cutting-edge techniques, graph neural networks and swap Monte\nCarlo, we develop a data-driven, property-oriented inverse design route that\nmanaged to improve the plastic resistance of Cu-Zr metallic glasses in a\ncontrollable way. Swap Monte Carlo, as \"sampler\", effectively explores the\nglass landscape, and graph neural networks, with high regression accuracy in\npredicting the plastic resistance, serves as \"decider\" to guide the search in\nconfiguration space. Via an unconventional strengthening mechanism, a\ngeometrically ultra-stable yet energetically meta-stable state is unraveled,\ncontrary to the common belief that the higher the energy, the lower the plastic\nresistance. This demonstrates a vast configuration space that can be easily\noverlooked by conventional atomistic simulations. The data-driven techniques,\nstructural search methods and optimization algorithms consolidate to form a\ntoolbox, paving a new way to the design of glassy materials.",
        "positive": "High-temperature thermoelectric properties of the double-perovskite\n  ruthenium oxide (Sr$_{1-x}$La$_x$)$_2$ErRuO$_6$: We have prepared polycrystalline samples of (Sr$_{1-x}$La$_x$)$_2$ErRuO$_6$\nand (Sr$_{1-x}$La$_x$)$_2$YRuO$_6$, and have measured the resistivity, Seebeck\ncoefficient, thermal conductivity, susceptibility and x-ray absorption in order\nto evaluate the electronic states and thermoelectric properties of the doped\ndouble-perovskite ruthenates. We have observed a large Seebeck coefficient of\n-160 $\\mu$V/K and a low thermal conductivity of 7 mW/cmK for $x$=0.1 at 800 K\nin air. These two values are suitable for efficient oxide thermoelectrics,\nalthough the resistivity is still as high as 1 $\\Omega$cm. From the\nsusceptibility and x-ray absorption measurements, we find that the doped\nelectrons exist as Ru$^{4+}$ in the low spin state. On the basis of the\nmeasured results, the electronic states and the conduction mechanism are\ndiscussed."
    },
    {
        "anchor": "Ab initio Description of Bond-Breaking in Large Electric Fields: Strong ($10^{10}$ V/m) electric fields capable of inducing atomic\nbond-breaking represent a powerful tool for surface chemistry. However, their\nexact effects are difficult to predict due to a lack of suitable tools to probe\ntheir associated atomic-scale mechanisms. Here we introduce a generalized\ndipole correction for charged repeated-slab models that controls the electric\nfield on both sides of the slab, thereby enabling direct theoretical treatment\nof field-induced bond-breaking events. As a prototype application, we consider\nfield evaporation from a kinked W surface. We reveal two qualitatively\ndifferent desorption mechanisms that can be selected by the magnitude of the\napplied field.",
        "positive": "Magnetostriction-induced anisotropy in the exchange biased bilayers: The exchange bias at ferromagnetic/antiferromagnetic interfaces strongly\ndepends upon the state of antiferromagnetic (AF) layer which, due to strong\nmagnetoelastic coupling, is sensitive to mechanical stresses. In the present\npaper we consider magnetoelastic effects that arise at FM/AF interface due to\nlattice misfit and magnetic ordering. We show how magnetostriction affects\nmutual orientation of AF and FM vectors and easy-axis direction in thin AF\nlayer. The results obtained could be used for tailoring exchange biased\nsystems."
    },
    {
        "anchor": "Boundary spin Hall effect in a two-dimensional semiconductor system with\n  Rashba spin-orbit coupling: We derive boundary conditions for the coupled spin-charge diffusion equations\nat a transmitting interface between two-dimensional electron systems with\ndifferent strengths of the Rashba spin-orbit (SO) coupling $\\alpha$, and an\nelectric field parallel to the interface. We consider the limit where the\nspin-diffusion length l_s is long compared to the electron mean free path l,\nand assume that $\\alpha$ changes discontinuously on the scale of l_s. We find\nthat the spin density is also discontinuous on the scale of l_s. In the case\nwhere the electron mobility is constant across the interface, this leads to the\ncomplete suppression of the expected spin injection from a region with\n$\\alpha\\neq0$ into a non-SO region with $\\alpha=0$.",
        "positive": "Toward Accurate Interpretable Predictions of Materials Properties within\n  Transformer Language Models: Property prediction accuracy has long been a key parameter of machine\nlearning in materials informatics. Accordingly, advanced models showing\nstate-of-the-art performance turn into highly parameterized black boxes missing\ninterpretability. Here, we present an elegant way to make their reasoning\ntransparent. Human-readable text-based descriptions automatically generated\nwithin a suite of open-source tools are proposed as materials representation.\nTransformer language models pretrained on 2 million peer-reviewed articles take\nas input well-known terms, e.g., chemical composition, crystal symmetry, and\nsite geometry. Our approach outperforms crystal graph networks by classifying\nfour out of five analyzed properties if one considers all available reference\ndata. Moreover, fine-tuned text-based models show high accuracy in the\nultra-small data limit. Explanations of their internal machinery are produced\nusing local interpretability techniques and are faithful and consistent with\ndomain expert rationales. This language-centric framework makes accurate\nproperty predictions accessible to people without artificial-intelligence\nexpertise."
    },
    {
        "anchor": "Uncovering hidden spin polarization of energy bands in antiferromagnets: Many textbook physical effects in crystals are enabled by some specific\nsymmetries. In contrast to such \"apparent effects\", \"hidden effect X\" refers to\nthe general condition where the nominal global system symmetry would disallow\nthe effect X, whereas the symmetry of local sectors within the crystal would\nenable effect X. Known examples include the hidden Rashba and/or hidden\nDresselhaus spin polarization that require spin orbit coupling, but (unlike the\napparent Rashba and Dresselhaus counterparts) can exist even in\ninversion-symmetric non-magnetic crystals. Here we point out that the spin\nsplitting effect that does not require spin-orbit coupling (SOC) can have a\nhidden spin polarization counterpart in antiferromagnets. We show that such\nhidden, SOC-independent effects reflect intrinsic properties of the perfect\ncrystal rather than an effect due to imperfections, opening the possibility for\nexperimental realization, and offering a potential way to switch\nantiferromagnetic ordering.",
        "positive": "Optical properties and electronic structure of multiferroic hexagonal\n  orthoferrites RFeO3 (R=Ho, Er, Lu): We report on optical studies of the thin films of multiferroic hexagonal\n(P.G. 6mm) rare-earth orthoferrites RFeO3 (R=Ho, Er, Lu) grown epitaxially on a\n(111)-surface of ZrO2(Y2O3) substrate. The optical absorption study in the\nrange of 0.6-5.6 eV shows that the films are transparent below 1.9 eV; above\nthis energy four broad intense absorption bands are distinguished. The\nabsorption spectra are analyzed taking into account the unusual fivefold\ncoordination of the Fe(3+) ion. Temperature dependence of the optical\nabsorption at 4.9 eV shows anomaly at 124 K, which we attribute to magnetic\nordering of iron sublattices."
    },
    {
        "anchor": "Ideal Bandgap in a 2D Ruddlesden-Popper Perovskite Chalcogenide for\n  Single-junction Solar Cells: Transition metal perovskite chalcogenides (TMPCs) are explored as stable,\nenvironmentally friendly semiconductors for solar energy conversion. They can\nbe viewed as the inorganic alternatives to hybrid halide perovskites, and\nchalcogenide counterparts of perovskite oxides with desirable optoelectronic\nproperties in the visible and infrared part of the electromagnetic spectrum.\nPast theoretical studies have predicted large absorption coefficient, desirable\ndefect characteristics, and bulk photovoltaic effect in TMPCs. Despite recent\nprogresses in polycrystalline synthesis and measurements of their optical\nproperties, it is necessary to grow these materials in high crystalline quality\nto develop a fundamental understanding of their optical properties and evaluate\ntheir suitability for photovoltaic application. Here, we report the growth of\nsingle crystals of a two-dimensional (2D) perovskite chalcogenide, Ba3Zr2S7,\nwith a natural superlattice-like structure of alternating double-layer\nperovskite blocks and single-layer rock salt structure. The material\ndemonstrated a bright photoluminescence peak at 1.28 eV with a large external\nluminescence efficiency of up to 0.15%. We performed time-resolved\nphotoluminescence spectroscopy on these crystals and obtained an effective\nrecombination time of ~65 ns. These results clearly show that 2D\nRuddlesden-Popper phases of perovskite chalcogenides are promising materials to\nachieve single-junction solar cells.",
        "positive": "Aluminium storage using nitrogen-doped graphene nanoribbons from first\n  principles: Pristine graphene interacts relatively weakly with Al, which is a specie of\nimportance for novel generations of metal-ion batteries. We employ DFT\ncalculations to explore the possibility of enhancing Al interaction with\ngraphene. We investigate non-doped and N-doped graphene nanoribbons, address\nthe impact of the edge sites, which are always present to some extent in real\nsamples, and N-containing defects on the material's reactivity towards Al. The\nresults are compared to that of pristine graphene. We show that introduction of\nedges does not affect the energetics of Al adsorption significantly by itself.\nOn the other hand, N-doping of graphene nanoribbons is found to affect the\nadsorption energy of Al to the extent that strongly depends on the type of\nN-containing defect. While graphitic and pyrrolic N induce minimal changes, the\nintroduction of edge NO group and doping with in plane pyridinic N result in Al\nadsorption nearly twice as strong as on pristine graphene. The obtained results\ncould guide the further design of advanced materials for Al-ion rechargeable\nbatteries."
    },
    {
        "anchor": "Lateral length scales in exchange bias: When a ferromagnet is in proximity with an antiferromagnet, lateral length\nscales such as the respective magnetic domain sizes drastically affect the\nexchange bias. Bilayers of FeF2 and either Ni, Co or Fe are studied using SQUID\nand spatially resolved MOKE. When the antiferromagnetic domains are larger than\nor comparable to the ferromagnetic domains, a local, non-averaging exchange\nbias is observed. This gives rise to unusual and tunable magnetic hysteresis\ncurves.",
        "positive": "Laser-ablation-assisted SF6 decomposition for extensive and controlled\n  fluorination of graphene: We present a safe, clean, convenient, and easy-to-control method for\nextensive fluorination of graphene using laser-ablation-assisted decomposition\nof gaseous SF6 molecules."
    },
    {
        "anchor": "Large-Gap Two-Dimensional Topological Insulator in Oxygen Functionalized\n  MXene: Two-dimensional (2D) topological insulator (TI) have been recognized as a new\nclass of quantum state of matter. They are distinguished from normal 2D\ninsulators with their nontrivial band-structure topology identified by the\n$Z_2$ number as protected by time-reversal symmetry (TRS). 2D TIs have\nintriguing spin-velocity locked conducting edge states and insulating\nproperties in the bulk. In the edge states, the electrons with opposite spins\npropagate in opposite directions and the backscattering is fully prohibited\nwhen the TRS is conserved. This leads to quantized dissipationless \"two-lane\nhighway\" for charge and spin transportation and promises potential\napplications. Up to now, only very few 2D systems have been discovered to\npossess this property. The lack of suitable material obstructs the further\nstudy and application. Here, by using first-principles calculations, we propose\nthat the functionalized MXene with oxygen, M$_2$CO$_2$ (M=W, Mo and Cr), are 2D\nTIs with the largest gap of 0.194 eV in W case. They are dynamically stable and\nnatively antioxidant. Most importantly, they are very likely to be easily\nsynthesized by recent developed selective chemical etching of transition-metal\ncarbides (MAX phase). This will pave the way to tremendous applications of 2D\nTIs, such as \"ideal\" conducting wire, multifunctional spintronic device, and\nthe realization of topological superconductivity and Majorana modes for quantum\ncomputing.",
        "positive": "High Pressure Structure and Decomposition of MoS$_{2}$: The high pressure structural and electronic evolution of bulk MoS$_2$, an\nimportant transition metal layered dichalchogenide, is currently under active\ninvestigation. Recent theoretical and experimental work predicted and verified\na 2H$_c \\to$ 2H$_a$ layer sliding structural transition at 20 GPa and a band\noverlap semiconductor-semimetal transition in the same pressure range. The\n2H$_a$ structure is known to persist up to pressure of 81 GPa but properties at\nhigher pressures remain experimentally unknown. Here we predict, with a\nreliable first-principles evolutionary search, that major structural\ntransformations should take place in equilibrium at higher pressures near\n130-140 GPa. The main motif is a decomposition into MoS + S, also heralded in a\nsmall bimolecular cell by the appearance of a metastable non-layered metallic\nMoS$_2$ structure with space group \\textit{P4/mmm}. Unlike semimetallic\n2H$_a$-MoS$_2$, both this phase and sulphur in the fully phase separated system\nare fully metallic and superconducting with higher critical temperatures than\nalkali-intercalated MoS$_2$."
    },
    {
        "anchor": "Theoretical investigation of decoherence channels in athermal phonon\n  sensors: The creation and evolution of nonequilibrium phonons is central in\napplications ranging from cosmological particle searches to decoherence\nprocesses in qubits. However, the fundamental understanding of decoherence\npathways for athermal phonon distributions in solid-state systems remains an\nopen question. Using first-principles calculations, we investigate the primary\ndecay channels of athermal phonons in two technologically relevant\nsemiconductors -- Si and GaAs. We quantify the contributions of anharmonic,\nisotopic, and interfacial scattering in these materials. From this, we\nconstruct a model to estimate the thermal power in a readout scheme as a\nfunction of time. We discuss the implication of our results on noise\nlimitations in current phonon sensor designs and strategies for improving\ncoherence in next-generation phonon sensors.",
        "positive": "Revisiting step instabilities on crystal surfaces. Part I: The\n  quasistatic approximation: Epitaxial growth on a surface vicinal to a high-symmetry crystallographic\nplane occurs through the propagation of atomic steps, a process called\nstep-flow growth. In some instances, the steps tend to form close groups (or\nbunches), a phenomenon termed step bunching, which corresponds to an\ninstability of the equal-spacing step propagation. Over the last fifty years,\nvarious mechanisms have been proposed to explain step bunching, the most\nprominent of which are the inverse Ehrlich-Schwoebel effect (i.e., the\nasymmetry which favors the attachment of adatoms from the upper terrace),\nelastically mediated interactions between steps (in heteroepitaxy), step\npermeability (in electromigration-controlled growth), and the chemical effect\n(which couples the diffusion fields on all terraces). Beyond the discussion of\nthe influence of each of these mechanisms taken independently on the propensity\nto bunching, we propose a unified treatment of the effect of these mechanisms\non the onset of the bunching instability, which also accounts for their\ninterplay. This is done in the setting of the so-called quasistatic\napproximation, which by permitting mostly analytical treatment, offers a clear\nview of the influence on stability of the combined mechanisms. In particular,\nwe find that the Ehrlich-Schwoebel effect, elastic step-interactions and the\nchemical effect combine in a quasi-additive fashion, whereas step permeability\nis neither stabilizing nor destabilizing per se but changes the relative\ninfluence of the three aforementioned mechanisms. In a companion paper, we\ndemonstrate and discuss the importance of another mechanism, which we call the\ndynamics effect, that emerges when relaxing the simplifying but questionable\nquasistatic approximation."
    },
    {
        "anchor": "Importance of anisotropic Coulomb interactions in the electronic and\n  magnetic properties of Mn$_3$O$_4$: We report the importance of anisotropic Coulomb interactions in DFT+U\ncalculations of the electronic and magnetic properties of Mn$_3$O$_4$. The\neffects of anisotropic interactions in Mn$^{2+}$ and Mn$^{3+}$ are separately\nexamined by defining two different sets of Hubbard parameters: $U^{2+}$ and\n$J^{2+}$ for Mn$^{2+}$ and $U^{3+}$ and $J^{3+}$ for Mn$^{3+}$. The anisotropic\ninteractions in Mn$^{3+}$ have a significant impact on the physical properties\nof Mn$_3$O$_4$ including local magnetic moments, canted angle, spontaneous\nmagnetic moment, and superexchange coupling, but those in Mn$^{2+}$ do not make\nany noticeable difference. Weak ferromagnetic interchain superexchange,\nobserved in experiments, is predicted only if a sizable anisotropic interaction\nis considered in Mn$^{3+}$. By analyzing the eigenoccupations of the on-site Mn\ndensity matrix, we found that the spin channel involving Mn$^{3+}$\n$d_{x^2-y^2}$ orbitals, which governs the 90$^\\circ$ correlation superexchange,\nis directly controlled by the anisotropic interactions. These findings\ndemostrate that the exchange correction $J$ for the intraorbital Coulomb\npotential is of critical importance for first-principles description of reduced\nMn oxides containing Mn$^{3+}$ or Mn$^{4+}$.",
        "positive": "Dirac Fermions in Antiferromagnetic FeSn Kagome Lattices with Combined\n  Space Inversion and Time Reversal Symmetry: Symmetry principles play a critical role in formulating the fundamental laws\nof nature, with a large number of symmetry-protected topological states\nidentified in recent studies of quantum materials. As compelling examples,\nmassless Dirac fermions are jointly protected by the space inversion symmetry\n$P$ and time reversal symmetry $T$ supplemented by additional crystalline\nsymmetry, while evolving into Weyl fermions when either $P$ or $T$ is broken.\nHere, based on first-principles calculations, we reveal that massless Dirac\nfermions are present in a layered FeSn crystal containing antiferromagnetically\ncoupled ferromagnetic Fe kagome layers, where each of the $P$ and $T$\nsymmetries is individually broken but the combined $PT$ symmetry is preserved.\nThese stable Dirac fermions protected by the combined $PT$ symmetry with\nadditional non-symmorphic $S_{\\rm{2z}}$ symmetry can be transformed to either\nmassless/massive Weyl or massive Dirac fermions by breaking the $PT$ or\n$S_{\\rm{2z}}$ symmetry. Our angle-resolved photoemission spectroscopy\nexperiments indeed observed the Dirac states in the bulk and two-dimensional\nWeyl-like states at the surface. The present study substantially enriches our\nfundamental understanding of the intricate connections between symmetries and\ntopologies of matter, especially with the spin degree of freedom playing a\nvital role."
    },
    {
        "anchor": "High-Entropy Hydrides for Fast and Reversible Hydrogen Storage at Room\n  Temperature: Binding-Energy Engineering via First-Principles Calculations and\n  Experiments: Despite high interest in compact and safe storage of hydrogen in the\nsolid-state hydride form, the design of alloys that can reversibly and quickly\nstore hydrogen at room temperature under pressures close to atmospheric\npressure is a long-lasting challenge. In this study, first-principles\ncalculations are combined with experiments to develop high-entropy alloys\n(HEAs) for room-temperature hydrogen storage. TixZr2-xCrMnFeNi (x = 0.4-1.6)\nalloys with the Laves phase structure and low hydrogen binding energies of -0.1\nto -0.15 eV are designed and synthesized. The HEAs reversibly store hydrogen in\nthe form of Laves phase hydrides at room temperature, while (de)hydrogenation\npressure systematically reduces with increasing the zirconium fraction in good\nagreement with the binding energy calculations. The kinetics of hydrogenation\nare fast, the hydrogenation occurs without any activation or catalytic\ntreatment, the hydrogen storage performance remains stable for at least 1000\ncycles, and the storage capacity is higher than that for commercial LaNi5. The\ncurrent findings demonstrate that a combination of theoretical calculations and\nexperiments is a promising pathway to design new high-entropy hydrides with\nhigh performance for hydrogen storage.",
        "positive": "Direct optical detection of Weyl fermion chirality in a topological\n  semimetal: A Weyl semimetal (WSM) is a novel topological phase of matter, in which Weyl\nfermions (WFs) arise as pseudo-magnetic monopoles in its momentum space. The\nchirality of the WFs, given by the sign of the monopole charge, is central to\nthe Weyl physics, since it directly serves as the sign of the topological\nnumber and gives rise to exotic properties such as Fermi arcs and the chiral\nanomaly. Despite being the defining property of a WSM, the chirality of the WFs\nhas never been experimentally measured. Here, we directly detect the chirality\nof the WFs by measuring the photocurrent in response to circularly polarized\nmid-infrared light. The resulting photocurrent is determined by both the\nchirality of WFs and that of the photons. Our results pave the way for\nrealizing a wide range of theoretical proposals for studying and controlling\nthe WFs and their associated quantum anomalies by optical and electrical means.\nMore broadly, the two chiralities, analogous to the two valleys in 2D\nmaterials, lead to a new degree of freedom in a 3D crystal with potential novel\npathways to store and carry information."
    },
    {
        "anchor": "Memory function formalism approach to electrical conductivity and\n  optical response of dilute magnetic semiconductors: A combination of the memory function formalism and time-dependent\ndensity-functional theory is applied to transport in dilute magnetic\nsemiconductors. The approach considers spin and charge disorder and\nelectron-electron interaction on an equal footing. Within the weak disorder\nlimit and using a simple parabolic approximation for the valence band we show\nthat Coulomb and exchange scattering contributions to the resistivity in GaMnAs\nare of the same order of magnitude. The positional correlations of defects\nresult in a significant increase of Coulomb scattering, while the suppression\nof localized spin fluctuations in the ferromagnetic phase contributes\nsubstantially to the experimentally observed drop of resistivity below T_c. A\nproper treatment of dynamical screening and collective excitations is essential\nfor an accurate description of infrared absorption.",
        "positive": "Simple Metals at High Pressure: In this lecture we review high-pressure phase transition sequences exhibited\nby simple elements, looking at the examples of the main group I, II, IV, V, and\nVI elements. General trends are established by analyzing the changes in\ncoordination number on compression. Experimentally found phase transitions and\ncrystal structures are discussed with a brief description of the present\ntheoretical picture."
    },
    {
        "anchor": "Understanding the role of Hubbard corrections in the rhombohedral phase\n  of BaTiO$_3$: We present a first-principles study of the low-temperature rhombohedral phase\nof BaTiO$_3$ using Hubbard-corrected density-functional theory. By employing\ndensity-functional perturbation theory, we compute the onsite Hubbard $U$ for\nTi($3d$) states and the intersite Hubbard $V$ between Ti($3d$) and O($2p$)\nstates. We show that applying the onsite Hubbard $U$ correction alone to\nTi($3d$) states proves detrimental, as it suppresses the Ti($3d$)-O($2p$)\nhybridization and drives the system towards a cubic phase. Conversely, when\nboth onsite $U$ and intersite $V$ are considered, the localized character of\nthe Ti($3d$) states is maintained, while also preserving the Ti($3d$)-O($2p$)\nhybridization, restoring the rhombohedral phase of BaTiO$_3$. The generalized\nPBEsol+$U$+$V$ functional yields good agreement with experimental results for\nthe band gap and dielectric constant, while the optimized geometry is slightly\nless accurate compared to PBEsol. Zone-center phonon frequencies and Raman\nspectra are found to be significantly influenced by the underlying geometry.\nPBEsol and PBEsol+$U$+$V$ provide satisfactory agreement with the experimental\nRaman spectrum when the PBEsol geometry is used, while PBEsol+$U$ Raman\nspectrum diverges strongly from experimental data highlighting the adverse\nimpact of the $U$ correction alone in BaTiO$_3$. Our findings underscore the\npromise of the extended Hubbard PBEsol+$U$+$V$ functional with first-principles\n$U$ and $V$ for the investigation of other ferroelectric perovskites with mixed\nionic-covalent interactions.",
        "positive": "Magnetic ordering induced by interladder coupling in the spin-1/2\n  Heisenberg two-leg ladder antiferromagnet C$_9$H$_{18}$N$_2$CuBr$_4$: We present specific-heat and neutron-scattering results for the \\emph{S}=1/2\nquantum antiferromagnet (dimethylammonium)(3,5-dimethylpyridinium)CuBr$_4$. The\nmaterial orders magnetically at \\emph{T}$_N$=1.99(2)\\,K, and magnetic\nexcitations are accompanied by an energy gap of 0.30(2) meV due to spin\nanisotropy. The system is best described as coupled two-leg spin-1/2 ladders\nwith the leg exchange $J_{\\rm leg}$=0.60(2)~meV, rung exchange $J_{\\rm\nrung}$=0.64(9)~meV, interladder exchange $J_{\\rm int}$=0.19(2)~meV, and an\ninteraction-anisotropy parameter $\\lambda$=0.93(2), according to inelastic\nneutron-scattering measurements. In contrast to most spin ladders reported to\ndate, the material is a rare example in which the interladder coupling is very\nnear the critical value required to drive the system to a N\\'eel-ordered phase\nwithout an assistance of a magnetic field."
    },
    {
        "anchor": "Crystal structure optimisation using an auxiliary equation of state: Standard procedures for local crystal-structure optimisation involve numerous\nenergy and force calculations. It is common to calculate an energy-volume\ncurve, fitting an equation of state around the equilibrium cell volume. This is\na computationally intensive process, in particular for low-symmetry crystal\nstructures where each isochoric optimisation involves energy minimisation over\nmany degrees of freedom. Such procedures can be prohibitive for non-local\nexchange-correlation functionals or other 'beyond' density functional theory\nelectronic structure techniques, particularly where analytical gradients are\nnot available. We present a simple approach for efficient optimisation of\ncrystal structures based on a known equation of state. The equilibrium volume\ncan be predicted from one single-point calculation, and refined with successive\ncalculations if required. The approach is validated for PbS, PbTe, ZnS and ZnTe\nusing nine density functionals, and applied to the quaternary semiconductor\nCu$_{2}$ZnSnS$_{4}$ and the magnetic metal-organic framework HKUST-1.",
        "positive": "Hysteresis in a system driven by either generalized force or\n  displacement variables: We report on experiments aimed at comparing the hysteretic response of a\nCu-Zn-Al single crystal undergoing a martensitic transition under strain-driven\nand stress-driven conditions. Strain-driven experiments were performed using a\nconventional tensile machine while a special device was designed to perform\nstress-driven experiments. Significant differences in the hysteresis loops were\nfound. The strain-driven curves show re-entrant behaviour (yield point) which\nis not observed in the stress-driven case. The dissipated energy in the\nstress-driven curves is larger than in the strain-driven ones. Results from\nrecently proposed models qualitatively agree with experiments."
    },
    {
        "anchor": "Excess Volume at Grain Boundaries in hcp Metals: The excess volume associated with grain boundaries represents a key\nstructural parameter for the characterization of grain boundaries. It plays a\ncritical role in segregation of impurity and alloy elements to grain\nboundaries, and influences significantly the mechanical and functional\nproperties of materials. We have carried out first-principles density\nfunctional calculations on the atomic structure of the (10-12) coherent twin\nboundary in hexagonal close packed (hcp) Ti and Zr and the basal-prismatic\nboundary in Zn, Cd, and Zr. We find the calculated excess volume has a\nvanishing magnitude at the (10-12) coherent twin boundary in Ti and Zr; whereas\nit is remarkable at the basal-prismatic boundary in Zn, Cd, and Zr.",
        "positive": "Control of Mechanical and Fracture Properties in Two-phase Materials\n  Reinforced by Continuous, Irregular Networks: Composites with high strength and high fracture resistance are desirable for\nstructural and protective applications. Most composites, however, suffer from\npoor damage tolerance and are prone to unpredictable fractures. Understanding\nthe behavior of materials with an irregular reinforcement phase offers\nfundamental guidelines for tailoring their performance. Here, we study the\nfracture nucleation and propagation in two phase composites, as a function of\nthe topology of their irregular microstructures. We use a stochastic algorithm\nto design the polymeric reinforcing network, achieving independent control of\ntopology and geometry of the microstructure. By tuning the local connectivity\nof isodense tiles and their assembly into larger structures, we tailor the\nmechanical and fracture properties of the architected composites, at the local\nand global scale. Finally, combining different reinforcing networks into a\nspatially determined meso-scale assembly, we demonstrate how the spatial\npropagation of fractures in architected composite materials can be designed and\ncontrolled a priori."
    },
    {
        "anchor": "Tensor gradiometry with a diamond magnetometer: Vector magnetometry provides more information than scalar measurements for\nmagnetic surveys utilized in space, defense, medical, geological and industrial\napplications. These areas would benefit from a mobile vector magnetometer that\ncan operate in extreme conditions. Here we present a scanning fiber-coupled\nnitrogen vacancy (NV) center vector magnetometer. Feedback control of the\nmicrowave excitation frequency is employed to improve dynamic range and\nmaintain sensitivity during movement of the sensor head. Tracking of the\nexcitation frequency shifts for all four orientations of the NV center allow us\nto image the vector magnetic field of a damaged steel plate. We calculate the\nmagnetic tensor gradiometry images in real time, and they allow us to detect\nsmaller damage than is possible with vector or scalar imaging.",
        "positive": "Controllable synthesis of single-, double- and triple-walled carbon\n  nanotubes from asphalt: Single-, double- and triple-walled carbon nanotubes (SWNTs, DWNTs and TWNTs)\nhave been controlla- bly synthesized by an arc discharge method using asphalt\nas carbon source. The morphology and struc- ture of three kinds of products\nsynthesized with Fe as catalyst were characterized by scanning electron\nmicroscopy (SEM), high-resolution transmission electron microscopy (HRTEM),\nRaman spectroscopy and energy dispersive X-ray spectroscopy (EDX). It was found\nthat different buffer gases strongly affect the number layers in the\nsynthesized nanotubes. In the He gas atmosphere only SWNTs were found to be\nsynthesized by arc discharge in contrast to the case in Ar gas atmosphere in\nwhich only TWNTs were formed. In N2 atmosphere both SWNTs and DWNTs were\nsynthesized. Our findings indicate that asphalt is a suitable industrial carbon\nsource for the growth of different type nanotubes."
    },
    {
        "anchor": "Well-localized edge states in two-dimensional topological insulators:\n  ultrathin Bi films: We theoretically study the generic behavior of the penetration depth of the\nedge states in two-dimensional quantum spin Hall systems. We found that the\nmomentum-space width of the edge-state dispersion scales with the inverse of\nthe penetration depth. As an example of well-localized edge states, we take the\nBi(111) ultrathin film. Its edge states are found to extend almost over the\nwhole Brillouin zone. Correspondingly, the bismuth (111) 1-bilayer system is\nproposed to have well-localized edge states in contrast to the HgTe quantum\nwell.",
        "positive": "Electronic Structure and Bulk Spin Valve Behavior in Ca$_3$Ru$_2$O$_7$: We report density functional calculations of the magnetic properties and\nFermiology of Ca$_3$Ru$_2$O$_7$. The ground state consists of ferromagnetic\nbilayers, stacked antiferromagnetically. The bilayers are almost but not\nexactly half-metallic. In the ferromagnetic state opposite spin polarizations\nare found for in-plane and out-of-plane transport. Relatively high out of plane\nconductivity is found for the majority spin, which is relatively weakly\nconductive in-plane. In the ground state in-plane quantities are essentially\nthe same, but the out of plane transport is strongly reduced."
    },
    {
        "anchor": "Comprehensive understanding of H adsorption on MoO3 from systematic ab\n  initio simulations: During many of its applications (especially as a catalyst support material),\nMoO3 acts as a medium for hydrogen storage via hydrogen spillover (H atom\ndonation from proton and electron sources to a support), for which the\nenergetics of H atoms on MoO3 are of importance. Despite the seeming simplicity\nof hydrogen spillover, previously reported ab initio results for the H\nadsorption on MoO3 contradict both experimental work and other ab initio\nresults. In the present study, we resolve these discrepancies and provide a\ncomprehensive ab initio understanding of H adsorption for MoO3 in the bulk and\non the surface. To this end, we systematically investigate various\nexchange-correlation functionals and various H concentrations, and we carefully\ntrack the various relevant H positions. For a dilute H concentration, the\nasymmetric oxygen site (Oa) is found to be energetically the most favorable.\nWith increasing H content, the difference of the H adsorption energies between\nthe terminal (Ot) and the Oa sites becomes smaller. Previous contradictions are\nascribed mostly to the disregard of the H position along the Oa-Oa zig-zag\nchains in the intrabilayer region. Using the modern non-empirical\nstrongly-constrained and appropriately-normed (SCAN) meta-generalized gradient\napproximation (GGA), the dilute-limit H adsorption energies are obtained as\n-2.89 eV/(H atom) and -2.97 eV/(H atom) in the bulk and on the surface,\nrespectively, and the activation energy of H diffusion between the Oa sites as\n0.11-0.15 eV/(H atom), consistent with previous experiments.",
        "positive": "Tuning the electronic structures and transport coefficients of Janus\n  PtSSe monolayer with biaxial strain: Due to their great potential in electronics, optoelectronics and\npiezoelectronics, Janus transition metal dichalcogenide (TMD) monolayers have\nattracted increasing research interest, the MoSSe of which with sandwiched\nS-Mo-Se structure has been synthesized experimentally. In this work, the\nbiaxial strain dependence of electronic structures and transport properties of\nJanus PtSSe monolayer is systematically investigated by using generalized\ngradient approximation (GGA) plus spin-orbit coupling (SOC). Calculated results\nshow that SOC has a detrimental effect on power factor of PtSSe monolayer,\nwhich can be understood by considering SOC effects on energy bands near the\nFermi level. With $a/a_0$ from 0.94 to 1.06, the energy band gap firstly\nincreases, and then decreases, which is due to the position change of\nconduction band minimum (CBM). It is found that compressive strain can increase\nthe strength of conduction bands convergence by changing relative position of\nconduction band extrema (CBE), which can enhance n-type $ZT_e$ values.\nCalculated results show that compressive strain can also induce the flat\nvalence bands around the $\\Gamma$ point near the Fermi level, which can lead to\nhigh Seebeck coefficient due to large effective masses, giving rise to better\np-type $ZT_e$ values. The calculated elastic constants with $a/a_0$ from 0.94\nto 1.06 all satisfy the mechanical stability criteria, which proves that the\nPtSSe monolayer is mechanically stable in the considered strain range. Our\nworks further enrich studies of Janus TMD monolayers, and can motivate farther\nexperimental works."
    },
    {
        "anchor": "Effect of Macroscopic Surface Heterogeneities on an Advancing Contact\n  Line: The shape of a liquid-air interface advancing on a heterogeneous surface was\nstudied experimentally, together with the force induced by the pinning of the\ncontact line to surface defects. Different surfaces were considered with\ncircular defects introduced as arrays of cocoa butter patches or small circular\nholes. These heterogeneous surfaces were submerged into aqueous ethanol\nsolutions, while measuring the additional force arising from the deformation of\nthe advancing contact line and characterising the interface shape and its\npinning on the defects. Initially, the submersion force is linear with\nsubmerged depth, suggesting a constant defect-induced stiffness. This regime\nends when the contact line de pins from the defects. A simple scaling is\nproposed to describe the depinning force and the depinning energy. We find\nthat, as the defect separation increases, the interface stiffness increases\ntoo, with a weak dependency on the defect radius. This interaction between\ndefects cannot be captured by the simple scaling, but can be well predicted by\na theory considering the interface deformation in presence of periodic arrays\nof holes. Creating a 4-phase contact line, by including solid defects (cocoa\nbutter) reduced pinning forces. The radius of the defect had a nonlinear effect\non the depinning depth. The 4-phase contact line resulted in depinning before\nthe defects are fully submerged. These experimental results and the associated\ntheory help understanding quantitatively the extent to which surface\nheterogeneities can slow down wetting. This in turn paves the way to tailor the\ndesign of heterogeneous surfaces, towards desired wetting performances.",
        "positive": "Scanning probe microscopy and spectroscopy of graphene on metals: Graphene, a two-dimensional (2D) material with unique electronic properties,\nappears to be an ideal object for the application of surface-science methods.\nAmong them, a family of scanning probe microscopy methods (STM, AFM, KPFM) and\nthe corresponding spectroscopy add-ons provide information about the structure\nand electronic properties of graphene on the local scale (from inline imagem to\natoms). This review focuses on the recent applications of these\nmicroscopic/spectroscopic methods for the investigation of graphene on metals\n(interfaces, intercalation-like systems, graphene nanoribbons, and quantum\ndots, etc.). It is shown that very important information about interaction\nstrength at the graphene/metal interfaces as well as about modification of the\nelectronic spectrum of graphene at the Fermi level can be obtained on the local\nscale. The combination of these results with those obtained by other methods\nand comparison with recent theoretical data demonstrate the power of this\napproach for the investigation of the graphene-based systems."
    },
    {
        "anchor": "Effects of topological edge states on the thermoelectric properties of\n  Bi nanoribbons: Using first-principles calculations combined with Boltzmann transport theory,\nwe investigate the effects of topological edge states on the thermoelectric\nproperties of Bi nanoribbons. It is found that there is a competition between\nthe edge and bulk contributions to the Seebeck coefficients. However, the\nelectronic transport of the system is dominated by the edge states because of\nits much larger electrical conductivity. As a consequence, a room temperature\nvalue exceeding 3.0 could be achieved for both p- and n-type systems when the\nrelaxation time ratio between the edge and the bulk states is tuned to be 1000.\nOur theoretical study suggests that the utilization of topological edge states\nmight be a promising approach to cross the threshold of the industrial\napplication of thermoelectricity.",
        "positive": "Atypical magnetic behavior in the incommensurate\n  $[CH_3NH_3][Ni(HCOO)_3]$ hybrid perovskite: A plethora of temperature induced phase transitions have been observed in\n$[CH_3NH_3][M(HCOO)_3]$ compounds, where M is Co(II) or Ni(II). Among them, the\nnickel compound exhibits a combination of magnetic and nuclear\nincommensurabil-ity below N\\'eel temperature. Despite the fact that the\nzero-field behavior has been previously addressed, here we study in depth the\nmacroscopic magnetic behavior of this compound to unveil the origin of the\natypical magnetic response found in it and in its parent family of formate\nperovskites. In particular, they show a puzzling magnetization reversal in the\ncurves measured starting from low temperatures, after cooling under zero field.\nThe first atypical phenomena is the im-possibility of reaching zero\nmagnetization, even by nullifying the applied external field and even\ncompensating it for the influence earth's magnetic field. Relatively large\nmagnetic fields are needed to switch the magnetization from negative to\npositive values or vice versa, which is compatible with a soft-ferromagnetic\nsystem. The atypical path found in its first magnetization curve and hysteresis\nloop at low temperatures is the most noticeable feature. The magnetization\ncurve switches from more than 1200 Oe from the first magnetization loop to the\nsubsequent magnetization loops. A feature that cannot be explained using a\nmodel based on unbalanced pair of domains. As a result, we decipher this\nbehavior in light of the incommensurate structure of this material. We propose,\nin particular, that the applied magnetic field induces a mag-netic phase\ntransition from a magnetically incommensurate structure to a magnetically\ncommensurate structure."
    },
    {
        "anchor": "Data Mining for Terahertz Generation Crystals: We demonstrate a data mining approach to discover and develop new organic\nnonlinear optical crystals that produce intense pulses of terahertz radiation.\nWe mine the Cambridge Structural Database for non-centrosymmetric materials and\nuse this structural data in tandem with density functional theory calculations\nto predict new materials that efficiently generate terahertz radiation. This\nenables us to (in a relatively short time) discover, synthesize, and grow\nlarge, high-quality crystals of four promising materials and characterize them\nfor intense terahertz generation. In a direct comparison to the current\nstate-of-the-art organic terahertz generation crystals, these new materials\nexcel. The discovery and characterization of these novel terahertz generators\nvalidates the approach of combining data mining with density functional theory\ncalculations to predict properties of high-performance organic materials,\npotentially for a host of exciting applications.",
        "positive": "Continuum variational and diffusion quantum Monte Carlo calculations: This topical review describes the methodology of continuum variational and\ndiffusion quantum Monte Carlo calculations. These stochastic methods are based\non many-body wave functions and are capable of achieving very high accuracy.\nThe algorithms are intrinsically parallel and well-suited to petascale\ncomputers, and the computational cost scales as a polynomial of the number of\nparticles. A guide to the systems and topics which have been investigated using\nthese methods is given. The bulk of the article is devoted to an overview of\nthe basic quantum Monte Carlo methods, the forms and optimisation of wave\nfunctions, performing calculations within periodic boundary conditions, using\npseudopotentials, excited-state calculations, sources of calculational\ninaccuracy, and calculating energy differences and forces."
    },
    {
        "anchor": "A Thermal Gradient Approach for the Quasi-Harmonic Approximation and its\n  Application to Improved Treatment of Anisotropic Expansion: We present a novel approach to efficiently implement thermal expansion in the\nquasi-harmonic approximation (QHA) for both isotropic and more importantly,\nanisotropic expansion. In this approach, we rapidly determine a crystal's\nequilibrium volume and shape at a given temperature by integrating along the\ngradient of expansion from zero Kelvin up to the desired temperature. We\ncompare our approach to previous isotropic methods that rely on a brute-force\ngrid search to determine the free energy minimum, which is infeasible to carry\nout for anisotropic expansion, as well as quasi-anisotropic approaches that\ntake into account the contributions to anisotropic expansion from the lattice\nenergy. We compare these methods for experimentally known polymorphs of\npiracetam and resorcinol and show that both isotropic methods agree to within\nerror up to 300 K. Using the Gr\\\"{u}neisen parameter causes up to 0.04 kcal/mol\ndeviation in the Gibbs free energy, but for polymorph free energy differences\nthere is a cancellation in error with all isotropic methods within 0.025\nkcal/mol at 300 K.\n  Anisotropic expansion allows the crystals to relax into lattice geometries\n0.01-0.23 kcal/mol lower in energy at 300 K relative to isotropic expansion.\nFor polymorph free energy differences all QHA methods produced results within\n0.02 kcal/mol of each other for resorcinol and 0.12 kcal/mol for piracetam, the\ntwo molecules tested here, demonstrating a cancellation of error for isotropic\nmethods.\n  We also find that when expanding in more than a single volume variable, there\nis a non-negligible rate of failure of the basic approximations of QHA.\nSpecifically, while expanding into new harmonic modes as the box vectors are\nincreased, the system often falls into alternate, structurally distinct\nharmonic modes unrelated by continuous deformation from the original harmonic\nmode.",
        "positive": "Radiative capture rates at deep defects from electronic structure\n  calculations: We present a methodology to calculate radiative carrier capture coefficients\nat deep defects in semiconductors and insulators from first principles.\nElectronic structure and lattice relaxations are accurately described with\nhybrid density functional theory. Calculations of capture coefficients provide\nan additional validation of the accuracy of these functionals in dealing with\nlocalized defect states. We also discuss the validity of the Condon\napproximation, showing that even in the event of large lattice relaxations the\napproximation is accurate. We test the method on\nGaAs:$V_\\text{Ga}$-$\\text{Te}_\\text{As}$ and GaN:C$_\\text{N}$, for which\nreliable experiments are available, and demonstrate very good agreement with\nmeasured capture coefficients."
    },
    {
        "anchor": "Electronic Structure Modulation from Configuring Anatase TiO2 into a\n  Bicontinuous Mesostructure: Configuring TiO2 into bicontinuous mesostructures greatly improves its\nphotocatalytic efficiency. This is often ascribed to the expanded surface area.\nYet, whether mesostructuring modulates TiO2's electronic structure and how that\ncontributes to the improvement are rarely discussed. Here, we employed\nspectroscopic and density functional theory approaches to address the question.\nIt is found that the improved efficacy could arise from an expansion in surface\narea and elevation in density of states, both of which might collectively lead\nto the observed reduction in charge-carrier recombination.",
        "positive": "Interfacial electrical and chemical properties of deposited SiO2 layers\n  in lateral implanted 4H-SiC MOSFETs subjected to different nitridations: In this paper, SiO2 layers deposited on 4H-SiC and subjected to different\npost deposition annealing (PDA) in NO and N2O were studied to identify the key\nfactors influencing the channel mobility and threshold voltage stability in\n4H-SiC MOSFETs. In particular, PDA in NO gave a higher channel mobility (55\ncm2V-1s-1) than PDA in N2O (20 cm2V-1s-1), and the subthreshold behavior of the\ndevices confirmed a lower total amount of interface states for the NO case.\nThis latter could be also deduced from the behavior of the capacitance-voltage\ncharacteristics of 4H-SiC MOSFETs measured in gate controlled diode\nconfiguration. On the other hand, cyclic gate bias stress measurements allowed\nto separate the contributions of interface states (Nit) both on the upper and\nbottom parts of the 4H-SiC band gap and near interface oxide traps (NIOTs) in\nthe two oxides. In particular, it was found that NO annealing reduced the total\ndensity of charges trapped at the interface states down to 3 x 1011 cm- 2 and\nthose trapped inside the oxide down to 1 x 1011 cm-2. Electron energy loss\nspectroscopy demonstrated that the reduction of these traps in the NO annealed\nsample is due to the lower amounts of sub-stoichiometric silicon oxide (~ 1nm)\nand carbon-related defects (< 1nm) at the interface, respectively. This\ncorrelation represents a further step in the comprehension of the physics of\nthe SiO2/4H-SiC interface explaining the mobility and threshold voltage\nbehavior of 4H-SiC MOSFETs."
    },
    {
        "anchor": "Visualization of carrier transport in lateral metal-perovskite-metal\n  structures and its influence on device operation: The high performance of hybrid perovskite based devices is attributed to its\nexcellent bulk-transport properties. However, carrier dynamics, especially at\nthe metal-perovskite interface, and its influence on device operation are not\nwidely understood. This work presents the dominant transport mechanisms in\nmethylammonium lead iodide (MAPbI3) perovskite-based asymmetric metal-electrode\nlateral devices. The device operation is studied with inter-electrode lengths\nvarying from 4 {\\mu}m to 120 {\\mu}m. Device characteristics indicate distinct\nohmic and space-charge limited current (SCLC) regimes that are controlled by\nthe inter-electrode length and applied bias. The electric-potential mapping\nusing Kelvin-Probe microscopy across the device indicates minimal ion-screening\neffects and the presence of a transport barrier at the metal-MAPbI3 junction.\nFurther, photocurrent imaging of the channel using near-field\nexcitation-scanning microscopy reveals dominant recombination and\ncharge-separation zones. These lateral devices exhibit photodetector\ncharacteristics with a responsivity of about 51 mA/W in self-powered mode and\n5.2 A/W at 5 V bias, in short-channel devices (4 {\\mu}m). The low device\ncapacitance enables a fast light-switching response of ~12 ns.",
        "positive": "Shape Evolution of CdSe Nanoparticles controlled by Halogen Compounds: Halogen compounds are capable of playing an important role in the\nmanipulation of nanoparticle shapes and properties. In a new approach, we\nexamined the shape evolution of CdSe nanorods to hexagonal pyramids in a\nhot-injection synthesis under the influence of halogenated additives in the\nform of organic chlorine, bromine and iodine compounds. Supported by DFT\ncalculations, this shape evolution is explained as a result of X-type ligand\ncoordination to sloped and flat Cd-rich facets and an equilibrium shape\nstrongly influenced by halides. Synchrotron XPS measurements and TXRF results\nshow that the shape evolution is accompanied by a modification in the chemical\ncomposition of the ligand sphere. Our experimental results suggest that the\nmolecular structure of the halogenated compound is related to the degree of the\neffect on both rod growth and further shape evolution. This presents a new\ndegree of freedom in nanoparticle shape control and highlights the role of\nadditives in nanoparticle synthesis and their possible in situ formation of\nligands."
    },
    {
        "anchor": "MgN: a new promising material for spintronic applications: Density functional theory calculations demonstrate that rocksalt MgN is a\nmagnetic material at the verge of half-metallicity, with an electronic\nstructure robust against strong correlations and spin-orbit interaction.\nFurthermore the calculated heat of formation describes the compound as\nmetastable and suggests that it can be fabricated by tuning the relative Mg and\nN abundance during growth. Intriguingly the equilibrium lattice constant is\nclose to that of MgO, so that MgN is likely to form as an inclusion during the\nfabrication of N-doped MgO. We then speculate that the MgO/MgN system may\nrepresent a unique materials platform for magnetic tunnel junctions not\nincorporating any transition metals.",
        "positive": "A telecom O-band emitter in diamond: Color centers in diamond are promising platforms for quantum technologies.\nMost color centers in diamond discovered thus far emit in the visible or\nnear-infrared wavelength range, which are incompatible with long-distance fiber\ncommunication and unfavorable for imaging in biological tissues. Here, we\nreport the experimental observation of a new color center that emits in the\ntelecom O-band, which we observe in silicon-doped bulk single crystal diamonds\nand microdiamonds. Combining absorption and photoluminescence measurements, we\nidentify a zero-phonon line at 1221 nm and phonon replicas separated by 42 meV.\nUsing transient absorption spectroscopy, we measure an excited state lifetime\nof around 270 ps and observe a long-lived baseline that may arise from\nintersystem crossing to another spin manifold."
    },
    {
        "anchor": "High-Mobility p-Channel Wide Bandgap Transistors Based on h-BN/Diamond\n  Heterostructures: Field-effect transistors made of wide-bandgap semiconductors can operate at\nhigh voltages, temperatures and frequencies with low energy losses, and have\nbeen of increasing importance in power and high-frequency electronics. However,\nthe poor performance of p-channel transistors compared with that of n-channel\ntransistors has constrained the production of energy-efficient complimentary\ncircuits with integrated n- and p-channel transistors. The p-type surface\nconductivity of hydrogen-terminated diamond offers great potential for solving\nthis problem, but surface transfer doping, which is commonly believed to be\nessential for generating the conductivity, limits the performance of\ntransistors made of hydrogen-terminated diamond because it requires the\npresence of ionized surface acceptors, which cause hole scattering. Here, we\nreport on fabrication of a p-channel wide-bandgap heterojunction field-effect\ntransistor consisting of a hydrogen-terminated diamond channel and hexagonal\nboron nitride ($h$-BN) gate insulator, without relying on surface transfer\ndoping. Despite its reduced density of surface acceptors, the transistor has\nthe lowest sheet resistance ($1.4$ k$\\Omega$) and largest on-current ($1600$\n$\\mu$m mA mm$^{-1}$) among p-channel wide-bandgap transistors, owing to the\nhighest hole mobility (room-temperature Hall mobility: $680$\ncm$^2$V$^{-1}$s$^{-1}$). Importantly, the transistor also shows normally-off\nbehavior, with a high on/off ratio exceeding $10^8$. These characteristics are\nsuited for low-loss switching and can be explained on the basis of standard\ntransport and transistor models. This new approach to making diamond\ntransistors paves the way to future wide-bandgap semiconductor electronics.",
        "positive": "Nanoscale Dichotomy of Ti 3d Carriers Mediating the Ferromagnetism in\n  Co:TiO2 Anatase Thin Films: We study the surface and bulk electronic structure of the room-temperature\nferromagnet Co:TiO2 anatase films using soft and hard x-ray photoemission\nspectroscopy with probe sensitivities of ~1 nm and ~10 nm, respectively. We\nobtain direct evidence of metallic Ti$^{3+}$ states in the bulk, which get\nsuppressed to give a surface semiconductor, thus indicating a surface-bulk\ndichotomy. X-ray absorption and high-sensitivity resonant photoemission\nspectroscopy reveal Ti$^{3+}$ electrons at the Fermi level (E$_F$) and\nhigh-spin Co$^{2+}$ electrons occurring away from E$_F$. The results show the\nimportance of the charge neutrality condition: Co$^{2+}$ + V$_{O}$$^{2-}$ +\n2Ti$^{4+}$ $\\leftrightarrow$ Co$^{2+}$ + 2Ti$^{3+}$ (V$_O$ is oxygen vacancy),\nwhich gives rise to the elusive Ti 3d carriers mediating ferromagnetism via the\nCo 3d-O 2p-Ti 3d exchange interaction pathway of the occupied orbitals."
    },
    {
        "anchor": "Single crystal growth of TIMETAL LCB titanium alloy by a floating zone\n  method: The methodology of single crystal growth of metastable $\\beta$-Ti alloy\nTIMETAL LCB in an optical floating zone furnace is presented in this paper.\nChemical compositions of both precursor material and single crystals were\nchecked. It was found that the concentration of base alloying elements did not\nchange significantly during the growth process, while the concentrations of\ninterstitial elements O and N increased. DSC measurement determined that this\nconcentration shift has a slight impact on ongoing phase transformations, as in\nthe single-crystalline material peak associated with $\\alpha$ phase\nprecipitation moves by a few degrees to a lower temperature and peak attributed\nto diffusion controlled growth of $\\omega$ particles shifts to a higher\ntemperature. X-ray reciprocal space maps were measured and their simulation\nshowed that the single crystal has a mosaic structure with mean size of mosaic\nblocks of approximately 60 nm.",
        "positive": "Direct Visualization of Electric Field induced Structural Dynamics in\n  Monolayer Transition Metal Dichalcogenides: Layered transition metal dichalcogenides (TMDs) offer many attractive\nfeatures for next-generation low-dimensional device geometries. Due to the\npractical and fabrication challenges related to in situ methods, the atomistic\ndynamics that give rise to realizable macroscopic device properties are often\nunclear. In this study, in situ transmission electron microscopy techniques are\nutilized in order to understand the structural dynamics at play, especially at\ninterfaces and defects, in the prototypical film of monolayer MoS2 under\nelectrical bias. Through our sample fabrication process, we clearly identify\nthe presence of mass transport in the presence of a lateral electric field. In\nparticular, we observe that the voids present at grain boundaries combine to\ninduce structural deformation. The electric field mediates a net vacancy flux\nfrom the grain boundary interior to the exposed surface edge sites that leaves\nmolybdenum clusters in its wake. Following the initial biasing cycles, however,\nthe mass flow is largely diminished, and the resultant structure remains stable\nover repeated biasing. We believe insights from this work can help explain\nobservations of non-uniform heating and preferential oxidation at grain\nboundary sites in these materials."
    },
    {
        "anchor": "Large-area synthesis of ferromagnetic Fe$_{5-x}$GeTe$_{2}$/graphene van\n  der Waals heterostructures with Curie temperature above room temperature: Van der Waals (vdW) heterostructures combining layered ferromagnets and other\ntwo-dimensional (2D) crystals are promising building blocks for the realization\nof ultra-compact devices with integrated magnetic, electronic and optical\nfunctionalities. Their implementation in various technologies depends strongly\non the development of a bottom-up scalable synthesis approach allowing to\nrealize highly uniform heterostructures with well-defined interfaces between\ndifferent 2D layered materials. It also requires that each material component\nof the heterostructure remains functional, which ideally includes ferromagnetic\norder above room temperature for 2D ferromagnets. Here, we demonstrate\nlarge-area growth of Fe$_{5-x}$GeTe$_{2}$/graphene heterostructures achieved by\nvdW epitaxy of Fe$_{5-x}$GeTe$_{2}$ on epitaxial graphene. Structural\ncharacterization confirmed the realization of a continuous vdW heterostructure\nfilm with a sharp interface between Fe$_{5-x}$GeTe$_{2}$ and graphene. Magnetic\nand transport studies revealed that the ferromagnetic order persists well above\n300 K with a perpendicular magnetic anisotropy. In addition, epitaxial graphene\non SiC(0001) continues to exhibit a high electronic quality. These results\nrepresent an important advance beyond non-scalable flake exfoliation and\nstacking methods, thus marking a crucial step toward the implementation of\nferromagnetic 2D materials in practical applications.",
        "positive": "Ultrasonic probing of the elastic properties of PMMA bead packings and\n  their rearrangement during pressure sintering: Ultrasound transmission in PMMA spherical bead packings is investigated\nduring the sintering process under stress. Velocity and amplitude measurements\nof coherent longitudinal waves are performed to monitor the evolution of the\nelastic properties of the solid frame from noncohesive packing to sintered\ngranular material. Comparison between the experimental velocity data and the\nprediction by a contact model [Digby, J. Appl. Mech. 48, 803, (1981)] reveals\nthe crucial role of the bonding effect on the mechanical behavior of granular\ncompacts. By using the correlation technique of acoustic speckles, we also\nobserve the important rearrangements in granular packings before the onset of\nsintering."
    },
    {
        "anchor": "Morphological characterization of shocked porous material: Morphological measures are introduced to probe the complex procedure of shock\nwave reaction on porous material. They characterize the geometry and topology\nof the pixelized map of a state variable like the temperature. Relevance of\nthem to thermodynamical properties of material is revealed and various\nexperimental conditions are simulated. Numerical results indicate that, the\nshock wave reaction results in a complicated sequence of compressions and\nrarefactions in porous material. The increasing rate of the total fractional\nwhite area $A$ roughly gives the velocity $D$ of a compressive-wave-series.\nWhen a velocity $D$ is mentioned, the corresponding threshold contour-level of\nthe state variable, like the temperature, should also be stated. When the\nthreshold contour-level increases, $D$ becomes smaller. The area $A$ increases\nparabolically with time $t$ during the initial period. The $A(t)$ curve goes\nback to be linear in the following three cases: (i) when the porosity $\\delta$\napproaches 1, (ii) when the initial shock becomes stronger, (iii) when the\ncontour-level approaches the minimum value of the state variable. The area with\nhigh-temperature may continue to increase even after the early\ncompressive-waves have arrived at the downstream free surface and some\nrarefactive-waves have come back into the target body. In the case of energetic\nmaterial ... (see the full text)",
        "positive": "Observation of Electrically Tunable van Hove Singularities in Twisted\n  Bilayer Graphene from nanoARPES: The possibility of triggering correlated phenomena by placing a singularity\nof the density of states near the Fermi energy remains an intriguing avenue\ntowards engineering the properties of quantum materials. Twisted bilayer\ngraphene is a key material in this regard because the superlattice produced by\nthe rotated graphene layers introduces a van Hove singularity and flat bands\nnear the Fermi energy that cause the emergence of numerous correlated phases,\nincluding superconductivity. While the twist angle-dependence of these\nproperties has been explored, direct demonstration of electrostatic control of\nthe superlattice bands over a wide energy range has, so far, been critically\nmissing. This work examines a functional twisted bilayer graphene device using\nin-operando angle-resolved photoemission with a nano-focused light spot. A\ntwist angle of 12.2$^{\\circ}$ is selected such that the superlattice Brillouin\nzone is sufficiently large to enable identification of van Hove singularities\nand flat band segments in momentum space. The doping dependence of these\nfeatures is extracted over an energy range of 0.4 eV, expanding the\ncombinations of twist angle and doping where they can be placed at the Fermi\nenergy and thereby induce new correlated electronic phases in twisted bilayer\ngraphene."
    },
    {
        "anchor": "Correlation between resistance fluctuations and temperature dependence\n  of conductivity in graphene: The weak temperature dependence of the resistance R(T) of monolayer\ngraphene1-3 indicates an extraordinarily high intrinsic mobility of the charge\ncarriers. Important complications are the presence of mobile scattering centres\nthat strongly modify charge transport, and the presence of strong mesoscopic\nconductance fluctuations that, in graphene, persist to relatively high\ntemperatures4,5. In this Letter, we investigate the surprisingly varied changes\nin resistance that we find in graphene flakes as temperature is lowered below\n70 K. We propose that these changes in R(T) arise from the temperature\ndependence of the scattered electron wave interference that causes the\nresistance fluctuations. Using the field effect transistor configuration, we\nverify this explanation in detail from measurements of R(T) by tuning to\ndifferent gate voltages corresponding to particular features of the resistance\nfluctuations. We propose simple expressions that model R(T) at both low and\nhigh charge carrier densities.",
        "positive": "Understanding the Effect of Lead Iodide Excess on the Performance of\n  Methylammonium Lead Iodide Perovskite Solar Cells: The presence of unreacted lead iodide in organic-inorganic lead halide\nperovskite solar cells is widely correlated with an increase in power\nconversion efficiency. We investigate the mechanism for this increase by\nidentifying the role of surfaces and interfaces present between methylammonium\nlead iodide perovskite films and excess lead iodide. We show how type I and II\nband alignments arising under different conditions result in either passivation\nof surface defects or hole injection. Through first-principles simulations of\nsolid-solid interfaces, we find that lead iodide captures holes from\nmethylammonium lead iodide and modulates the formation of defects in the\nperovskite, affecting recombination. Using surface-sensitive optical\nspectroscopy techniques, such as transient reflectance and time-resolved\nphotoluminescence, we show how excess lead iodide affects the diffusion and\nsurface recombination velocity of charge carriers in methylammonium lead iodide\nfilms. Our coupled experimental and theoretical results elucidate the role of\nexcess lead iodide in perovskite solar cells."
    },
    {
        "anchor": "Nonequilibrium free-energy calculation of solids using LAMMPS: This article describes nonequilibrium techniques for the calculation of free\nenergies of solids using molecular dynamics (MD) simulations. These methods\nprovide an alternative to standard equilibrium thermodynamic integration\nmethods and often present superior efficiency. Here we describe the\nimplementation in the LAMMPS (Large-scale Atomic/Molecular Massively Parallel\nSimulator) code of two specific nonequilibrium processes that allow the\ncalculation of the free-energy difference between two different system\nHamiltonians as well as the free-energy temperature dependence of a given\nHamiltonian, respectively. The theory behind the methods is summarized, and we\ndescribe (including fragments of LAMMPS scripts) how the process parameters\nshould be selected to obtain the best-possible efficiency in the calculations\nof free energies using nonequilibrium MD simulations. As an example of the\napplication of the methods we present results related to polymorphic\ntransitions for a classical potential model of iron.",
        "positive": "Micromagnetics of anti-skyrmions in ultrathin films: We present a combined analytical and numerical micromagnetic study of the\nequilibrium energy, size and shape of anti-skyrmionic magnetic configurations.\nAnti-skyrmions can be stabilized when the Dzyaloshinskii-Moriya interaction has\nopposite signs along two orthogonal in-plane directions, breaking the magnetic\ncircular symmetry. We compare the equilibrium energy, size and shape of\nanti-skyrmions and skyrmions that are stabilized respectively in environments\nwith anisotropic and isotropic Dzyaloshinskii-Moriya interaction, but with the\nsame strength of the magnetic interactions.When the dipolar interactions are\nneglected the skyrmion and the anti-skyrmion have the same energy, shape and\nsize in their respective environment. However, when dipolar interactions are\nconsidered, the energy of the anti-skyrmion is strongly reduced and its\nequilibrium size increased with respect to the skyrmion. While the skyrmion\nconfiguration shows homochiral N\\'{e}el magnetization rotations, anti-skyrmions\nshow partly N\\'{e}el and partly Bloch rotations. The latter do not produce\nmagnetic charges and thus cost less dipolar energy. Both magnetic\nconfigurations are stable when the magnetic energies almost cancel each other,\nwhich means that a small variation of one parameter can drastically change\ntheir configuration, size and energy."
    },
    {
        "anchor": "Dipole Ordering of Water Molecules in Cordierite: Monte Carlo\n  Simulations: Electric dipoles of water molecules, enclosed singly in regularly spaced\nnanopores of a cordierite crystal, become ordered at low temperature due to\ntheir mutual interaction and show the frequency dependence of their dielectric\nsusceptibility, typical for relaxor ferroelectrics, according to recent\nexperimental data. The corresponding phase transition is accompanied by\nanomalies in thermodynamic quantities, such as heat capacity and dielectric\nsusceptibility, which are calculated here using the Monte Carlo method, and\ntheir agreement the experimental data is discussed. Despite the increase in the\ncorrelation length, the partially filled dipole lattice at low temperatures,\naccording to the calculations, does not have long-range order and corresponds\nto a dipole glass. This simulation gives a microscopical insight into the\nformation of polar nanoregions in relaxor ferroelectrics and the temperature\ndependence of their size.",
        "positive": "Giant magnetoimpedance of composite wires with an insulation layer: Composite wires with a three-layered structure exhibit a large giant\nmagneto-impedance (GMI) effect, which can be used in sensitive magnetic field\nsensors. To further investigate the origin of the GMI effect, composite wires\nconsisting of a highly conductive copper core, a silicon dioxide layer and an\nouter Permalloy shell were prepared by radio frequency (RF) magnetron\nsputtering. The GMI ratio was measured at various driving current frequencies\nand with different insulating layer thicknesses. A theoretical model by\ncoupling the Maxwell equations to the Landau-Lifschitz-Gilbert equation was\ndeveloped to investigate the composite wire impedance and its dependence on\nexternal magnetic field, current frequency and insulating layer thickness.\nExperimental results corroborate the theoretical model."
    },
    {
        "anchor": "Magneto-thermally Activated Spin-state Transition in La0.95Ca0.05CoO3:\n  Magnetically-tunable Dipolar Glass and Giant Magneto-electricity: Magneto-dielectric spectra of La0.95Ca0.05CoO3 covering the crossover of spin\nstates reveals strong coupling of its spin and dipolar degrees of freedom.\nSignature of spin-state transition at 30K clearly manifests in magnetization,\nsupported by Co L_3,2-edge XAS data on the doped-specimen as consistent with\nits suppressed T_SST vs. ~150K for pure LaCoO3. Dispersive activation-step\n{\\Delta}{\\epsilon}'(T_{\\omega})~O(10^2) and relaxation-peak\n{\\epsilon}\"(T_{\\omega}) reflect the allied influence of coexistent spin-states\non the dielectric character. Dipolar relaxation in the LS regime below T_SST is\npartly segmental (VFT kinetics) featuring magnetic-field tunability, whereas in\nthe LS/IS-spin disordered state above 30K, it is uncorrelated (Arrhenic\nkinetics) and almost impervious to the H-field. Kinetics-switchover defines the\ndipolar-glass transition temperature Tg(H), below which the\nmagneto-thermally-activated cooperative relaxations freeze-out by the VFT\ntemperature T_0(H). Applied H-field facilitates thermally-activated SST and\naccelerates the dipolar relaxations; a critical 5T field collapsing the entire\nkinetics into a single Arrhenic behavior. Magneto-electricity (ME) spanning\nsizable thermo-spectral range registers diverse signatures here in the kinetic,\nspectral, and field behaviors, in contrast to the static/perturbative ME\nobserved close to the spin-ordering in typical multiferroics. Intrinsic\nmagneto-dielectricity (50%) along with vanishing magneto-loss is obtained at\n(27K/50kHz)_9T. Sub-linear deviant field-hysteretic split seen in\n{\\epsilon}'(H)|_>4T suggests the emergence of robust dipoles organized into\nnano-clusters, realized by the internally-generated high magneto-electric\nfield. An elaborate {\\omega}-T multi-dispersions diagram maps the rich variety\nof phase/response patterns, revealing the highly-interacting magnetic and\nelectric moments in the system.",
        "positive": "The Optical Signatures of Stochastic Processes in Many-Body Exciton\n  Scattering: We review our recent quantum stochastic model for spectroscopic lineshapes in\nthe presence of a co-evolving and non-stationary background population of\nexcitations. Starting from a field theory description for interacting bosonic\nexcitons, we derive a reduced model whereby optical excitons are coupled to an\nincoherent background via scattering as mediated by their screened Coulomb\ncoupling. The Heisenberg equations of motion for the optical excitons are then\ndriven by an auxiliary stochastic population variable, which we take to be the\nsolution of an Ornstein-Uhlenbeck process. Here we discuss an overview of the\ntheoretical techniques we have developed as applied to predicting coherent\nnon-linear spectroscopic signals. We show how direct (Coulomb) and exchange\ncoupling to the bath give rise to distinct spectral signatures and discuss\nmathematical limits on inverting spectral signatures to extract the background\ndensity of states."
    },
    {
        "anchor": "Elasticity and piezoelectricity of zinc oxide crystals, single layers,\n  and possible single-walled nanotubes: The elasticity and piezoelectricity of zinc oxide (ZnO) crystals and single\nlayers are investigated from the first-principles calculations. It is found\nthat a ZnO thin film less than three Zn-O layers prefers a planar graphite-like\nstructure to the wurtzite structure. ZnO single layers are much more flexible\nthan graphite single layers in the elasticity and stronger than boron nitride\nsingle layers in the piezoelectricity. Single-walled ZnO nanotubes (SWZONTs)\ncan exist in principle because of their negative binding energy. The\npiezoelectricity of SWZONTs depends on their chirality. For most ZnO nanotubes\nexcept the zigzag type, twists around the tube axis will induce axial\npolarizations. A possible scheme is proposed to achieve the SWZONTs from the\nsolid-vapor phase process with carbon nanotubes as templates.",
        "positive": "Phonon-drag effect in FeGa3: The thermoelectric properties of single- and polycrystalline FeGa3 are\nsystematically investigated over a wide temperature range. At low temperatures,\nbelow 20 K, previously not known pronounced peaks in the thermal conductivity\n(400-800 W K^-1m-1) with corresponding maxima in the thermopower (in the order\nof -16000 microV/K) were found in single crystalline samples. Measurements in\nsingle crystals along [100] and [001] directions indicate only a slight\nanisotropy in both the electrical and thermal transport. From susceptibility\nand heat capacity measurements, a structural or magnetic phase transition was\nexcluded. Using density functional theory-based calculations, we have revisited\nthe electronic structure of FeGa3 and compared the magnetic (including\ncorrelations) and non-magnetic electronic density of states. Thermopower at\nfixed carrier concentrations are calculated using semi-classical Boltzmann\ntransport theory, and the calculated results match fairly with our experimental\ndata and exclude the possibility of strong electronic correlations as an\nexplanation for the low temperature enhancement. Eventually, after a careful\nreview, we assign the peaks in the thermopower as a manifestation of the\nphonon-drag effect, which is supported by thermopower measurements in a\nmagnetic field."
    },
    {
        "anchor": "Double exchange-driven spin pairing at the (001) surface of manganites: The (001) surface of La_{1-x}Ca_xMnO_3 system in various magnetic orderings\nis studied by first principle calculations. A general occurrence is that z^2\ndangling bond charge -- which is ``invisible'' in the formal valence picture --\nis promoted to the bulk gap/Fermi level region. This drives a\ndouble-exchange-like process that serves to align the surface Mn spin with its\nsubsurface neighbor, regardless of the bulk magnetic order. For heavy doping,\nthe locally ``ferromagnetic'' coupling is very strong and the moment enhanced\nby as much as 30% over the bulk value.",
        "positive": "Eliminating the broadening by finite aperture in Brillouin spectroscopy: We present a new optical arrangement which allows to avoid the broadening by\nfinite aperture in Brillouin spectroscopy. In this system, all the rays\nscattered at the same angle by the whole scattering volume are collected on a\nsingle pixel of the area detector. This allows to use large collection angles,\nincreasing the luminosity without lowering the accuracy of the frequency-shift\nand linewidth measurements. Several results of experimental checks are\nprovided, showing the efficiency of the device."
    },
    {
        "anchor": "DFT Calculations of Temperature-Dependent NQR Parameters in\n  \u03b1-paradichlorobenzene and \u03b2-HMX: A method for first principles predictions of observed temperature-dependent\nNQR spectra is presented using density functional theory (DFT) and the isobaric\nT-dependent NQR frequencies of 35Cl and 14N nuclei are computed for the two\nmolecular crystals (1) alpha-paradichlorobenzene, and (2) the nitroamine high\nexplosive beta-HMX (beta-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) over\na range of 200 K and up to room temperature. Notably, the method requires no\nsupposition of a form for the intermolecular potentials or wave functions,\nrequires no particular insight as to the nature of the internal motions or of\nthe chemical bonds present, and does not depend on the crystal structure,\nmaking the method amenable to any periodic solid for which experimentally\ndetermined structural data are available. For each substance, unit cells of\nvarious volume are prepared using experimentally determined atomic positions\nand cell parameters. In each of the prepared volume-corrected cells, a\nmolecular dynamics (MD) simulation generates a set of perturbed atomic\npositions, the collection of which is intended to represent the system at a\ngiven T,V. For each configuration of atoms generated along the MD trajectory,\nthe electric field gradient (EFG) tensors are computed at the site of each\nquadrupolar nucleus. The rotational displacements of the moving EFG principal\naxes from their equilibrium directions are used to apply a dynamic correction\nto the DFT-computed static-lattice NQR frequencies, resulting in\nfirst-principles DFT predictions of T-dependent NQR spectra at constant\npressure. Because the V-dependence from thermal expansion and the T-dependence\ndue to internal motions are simultaneously considered, the NQR's notoriously\nmodel-dependent temperature coefficients are computed entirely ab-initio.",
        "positive": "Transition from anomalous kinetics towards Fickian diffusion for Si\n  dissolution into amorphous Ge: Over the last years several experimental and theoretical studies of diffusion\nkinetics on the nanoscale have shown that the time evolution differs from the\nclassical Fickian law (kc=0.5). However, all work was based on crystalline\nsamples or models, so far. In this letter, we report on the diffusion kinetics\nof a thin amorphous-Si layer into amorphous-Ge to account for the rising\nimportance of amorphous materials in nanodevices. Employing surface sensitive\ntechnics, the initial kc was found at 0.7+-0.1. Moreover, after some monolayers\nof Si dissolved into the Ge, kc changes to the generally expected classical\nFickian law with kc=0.5."
    },
    {
        "anchor": "Formation of a Te-Ag Honeycomb Alloy: A New Type of Two-Dimensional\n  Material: Inspired by the unique properties of graphene, the focus in the literature is\nnow on investigations of various two-dimensional (2D) materials with the aim to\nexplore their properties for future applications. The group IV analogues of\ngraphene, i.e., silicene, germanene and stanene have been intensively studied\nin recent years. However, their semi-metallic band structures hamper their use\nin electronic applications. Hence, the synthesis of 2D materials with band gaps\nof various sizes has attracted a large interest. Here, we report a successful\npreparation of a 2D Te-Ag binary alloy with a honeycomb structure.\nAngle-resolved photoelectron spectroscopy (ARPES) in combination with\nfirst-principles calculations using density functional theory (DFT) confirmed\nthe formation of this binary alloy. The semiconducting property is verified by\nthe ARPES data and a direct gap of ~0.7 eV is predicted by the DFT\ncalculations.",
        "positive": "Magnetothermopower and magnetoresistance of single Co-Ni/Cu multilayered\n  nanowires: The magnetothermopower and the magnetoresistance of single Co Ni/Cu\nmultilayered nan-owires with various thicknesses of the Cu spacer are\ninvestigated. Both kinds of measurement have been performed as a function of\ntemperature (50 K to 325 K) and under applied magnetic fields perpendicular to\nthe nanowire axis, with magnitudes up to 15 % at room temperature. A linear\nrelation between thermopower S and electrical conductivity {\\sigma} of the\nnanowires is found, with the magnetic field as an implicit variable. Combining\nthe linear behavior of the S vs. {\\sigma} and the Mott formula, the energy\nderivative of the resistivity has been determined. In order to extract the true\nnanowire materials parameters from the measured thermopower, a simple model\nbased on the Mott formula is employed to distinguish the individual thermopower\ncontributions of the sample. By assuming that the non-diffusive thermopower\ncontributions of the nanowire can be neglected, it was found that the magnetic\nfield induced changes of thermopower and resistivity are equivalent. The\nemphasis in the present paper is on the comparison of the magnetoresistance and\nmagnetothermopower results and it is found that the same correlation is valid\nbetween the two sets of data for all samples, irrespective of the relative\nimportance of the giant magnetoresistance or anisotropic magnetoresistance\ncontributions in the various individual nanowires."
    },
    {
        "anchor": "Hierarchy of Domain Reconstruction Processes due to Charged Defect\n  Migration in Acceptor Doped Ferroelectrics: Evolution of a stripe array of polarization domains triggered by the oxygen\nvacancy migration in an acceptor doped ferroelectric is investigated in a\nself-consistent manner. A comprehensive model based on the\nLandau-Ginzburg-Devonshire approach includes semiconductor features due to the\npresence of electrons and holes, and effects of electrostriction and\nflexoelectricity especially significant near the free surface and domain walls.\nA domain array spontaneously formed in the absence of an external field is\nshown to undergo a reconstruction in the course of the gradual oxygen vacancy\nmigration driven by the depolarization fields. The charge defect accumulation\nnear the free ferroelectric surface causes a series of phenomena: (i) symmetry\nbreaking between the positive and negative c-domains, (ii) appearance of an\neffective dipole layer at the free surface followed by the formation of a\nsurface electrostatic potential, (iii) tilting and recharging of the domain\nwalls, especially pronounced at higher acceptor concentrations. An internal\nbias field determined by the gain in the free energy of the structure exhibits\ndependences of its amplitude on time and dopant concentration well comparable\nwith available experimental results on aging in BaTiO3.",
        "positive": "Anomalous resistivity upturn in the van der Waals ferromagnet\n  Fe$_5$GeTe$_2$: Fe$_5$GeTe$_2$ (n = 3, 4, 5) have recently attracted increasing attention due\nto their two-dimensional van der Waals characteristic and high temperature\nferromagnetism, which make promises for spintronic devices. The Fe(1) split\nsite is one important structural characteristic of Fe$_5$GeTe$_2$ which makes\nit very different from other Fe$_5$GeTe$_2$ (n = 3, 4) systems. The local\natomic disorder and short-range order can be induced by the split site. In this\nwork, the high-quality van der Waals ferromagnet Fe$_5$GeTe$_2$ were grown to\nstudy the low-temperature transport properties. We found a resistivity upturn\nbelow 10 K. The temperature and magnetic field dependence of the resistivity\nare in good agreement with a combination of the theory of disorder-enhanced\nthree-dimensional electron-electron and single-channel Kondo effect. The Kondo\neffect exists only at low magnetic field B < 3 T, while electron-electron\ndominates the appearance for the low-temperature resistivity upturn. We believe\nthat the enhanced three-dimensional electron-electron interaction in this\nsystem is induced by the local atomic structural disorder due to the split site\nof Fe(1). Our results indicate that the split site of Fe plays an important\nrole for the exceptional transport properties."
    },
    {
        "anchor": "Transient-Enhanced Surface Diffusion on Native-Oxide-Covered Si(001)\n  Nano-Structures during Vacuum Annealing: We report on the transient-enhanced shape transformation of nano-structured\nSi(001) surfaces upon in vacuo annealing at relatively low temperatures of\n1175K - 1225K for a few minutes. We find dramatic surface mass transport\nconcomitant with the development of low-energy facets on surfaces that are\ncovered by native oxide. The enhanced surface mass transport ceases after the\noxide is completely desorbed, and it is also not observed on surfaces where the\nnative oxide had been removed by HF before annealing.",
        "positive": "Observation of vacancy-related polaron states at the surface of anatase\n  and rutile TiO2 by high-resolution photoelectron spectroscopy: Defects in the surface region of a reducible oxide, as TiO2, have a profound\neffect on applications, while their nature is very much influenced by the\npossibility of small polaron formation. Here, we probe rutile (110) and anatase\n(101) single crystals via high-resolution ultraviolet photoelectron\nspectroscopy and resolve multiple components of the well-known defect state in\nthe band gap. In rutile, we find two at VBM+2.1 eV and VBM+1.4 eV, which we\nassign to subsurface polaron traps and vacancy-bound states, respectively,\nconfirming the predicted partial suppression of polaron formation at high\nvacancy concentration. New defects are created in situ on the anatase surface\nby the synchrotron beam. We assign a component at VBM+2.3 eV, which can be\nremoved by annealing, to polaron states associated with surface oxygen\nvacancies. We also identify a second component at VBM+1.6 eV, which can not be\nremoved by annealing, and is too deep to be associated with oxygen vacancies."
    },
    {
        "anchor": "Merging of Dirac points through uniaxial modulation on an optical\n  lattice: We analyze the scenario of modulating the potential strength of bound atoms\nin an optical honeycomb lattice patterned by an electric field to emulate\nuniaxial strain. This modulation can be achieved by a combination of the\nstrength of the patterned electric field and gauge vector effects using the\nFloquet approach. We show that such a modulation allows one to follow through a\ntopological transition between a semi-metal and a band insulator, when two\nnon-equivalent $K$ points merge as a function of the electric field strength.\nWe explicitly compute the wavefunctions for the moving $K$ points and the Chern\nnumbers up to the transition. Anisotropic effective masses and the insulating\ngap are described close to the semimetal-insulator transition.",
        "positive": "Dislocation dynamics prediction of the strength of Al-Cu alloys\n  containing shearable $\u03b8''$ precipitates: The critical resolved shear stress of an Al 4 wt. \\% Cu alloy containing a\nhomogeneous distribution of $\\theta''$ precipitates was determined by means of\ndislocation dynamics simulations. The size distribution, shape, orientation and\nvolume fraction of the precipitates in the alloy were obtained from\ntransmission electron microscopy observations while the parameters controlling\nthe dislocation/precipitate interactions (elastic mismatch, transformation\nstrains, dislocation mobility and cross-slip probability, etc.) were calculated\nfrom atomistic simulations. The precipitates were assumed to be either\nimpenetrable or shearable by the dislocations, the latter characterized by a\nthreshold shear stress that has to be overcome to shear the precipitate. The\npredictions of the simulations in terms of the critical resolved shear stress\nand of the dislocation/precipitate interaction mechanisms were in good\nagreement with the experimental results. It was concluded that the optimum\nstrength of this alloy is attained with a homogeneous distribution of\n$\\theta''$ precipitates whose average size ($\\approx$ 40 nm) is at the\ntransition between precipitate shearing and looping. Overall, the dislocation\ndynamics strategy presented in this paper is able to provide quantitative\npredictions of precipitate strengthening in metallic alloys."
    },
    {
        "anchor": "Magnetic correlations in YBaCo4O7 probed by single-crystal neutron\n  scattering: We have studied the frustrated system YBaCo4O7 generally described as an\nalternating stacking of Kagome and triangular layers of magnetic ions on a\ntrigonal lattice, by single crystal neutron diffraction experiments above the\nNeel ordering transition. Experimental data reveals pronounced magnetic diffuse\nscattering, which is successfully modeled by direct Monte-Carlo simulations.\nLong-range magnetic correlations are found along the c-axis, due to the\npresence of corner-sharing bipyramids, creating quasi one-dimensional order at\nfinite temperature. In contrast, in the Kagome layers ab-plane, the spin-spin\ncorrelation function -displaying a short-range 120 degrees configuration-\ndecays rapidly as typically found in spin-liquids. YBaCo4O7 experimentally\nrealizes a new class of two-dimensional frustrated systems where the strong\nout-of-plane coupling does not lift the in-plane degeneracy, but instead act as\nan external \"field\".",
        "positive": "Zinc-Blende group III-V/group IV epitaxy: importance of the miscut: Here, we clarify the central role of the miscut during group III-V/ group IV\ncrystal growth. We show that the miscut first impacts the initial antiphase\ndomain distribution, with two distinct nucleation-driven and terraces-driven\nregimes. It is then inferred how the antiphase domain distribution mean phase\nand mean lateral length are affected by the miscut. An experimental\nconfirmation is given through the comparison of antiphase domain distributions\nin GaP and GaSb/AlSb samples grown on nominal and vicinal Si substrates. The\nantiphase domain burying step of GaP/Si samples is then observed at the atomic\nscale by scanning tunneling microscopy. The steps arising from the miscut allow\ngrowth rate imbalance between the two phases of the crystal and the growth\nconditions can deeply modify the imbalance coefficient, as illustrated with\nGaAs/Si. We finally explain how a monodomain III-V semiconductor configuration\ncan be achieved even on low miscut substrates."
    },
    {
        "anchor": "Phase Stability in 3d-5d (NiPt and CuAu) and 3d-4d (NiPd and CuAg)\n  Systems: We show the differences in the stability of 3d-5d (NiPt and CuAu) and 3d-4d\n(NiPd and CuAg) alloys arise mainly due to relativistic corrections. The\nmagnetic properties of disordered NiPd and NiPt alloys also differ due to these\ncorrections which lead to increase in the separation between s-d bands of 5d\nelements in these alloys. For the magnetic case we analyze the results in terms\nof splitting of majority and minority spin d-band centers of the 3d elements.\nWe further examine the effect of relativistic corrections to the pair energies\nand order disorder transition temperatures in these alloys. The magnetic\nmoments and Curie temperatures have also been studied along with the short\nrange ordering/segregation effects in NiPt/NiPd alloys.",
        "positive": "A Novel Broadband Measurement Method for the Magnetoimpedance of Ribbons\n  and Thin Films: A novel broad-band measurement method of the MI in thin films and ribbons is\npresented. It is based on the automated measurement of the reflection\ncoefficient of a cell loaded with the sample. Illustrative results obtained\nwith a permalloy multilayer thin film are presented and discussed."
    },
    {
        "anchor": "An ab initio Local Exchange Approach to the Calculations of Tc of Dilute\n  Magnetic Semiconductors: The DFT calculations were performed of densities of states of semiconductor\nGaAs and magnetic semiconductor Ga0.9375Mn0.0625As. It is obtained that a part\nof Mn3d- states is hybridized with valence band at Fermi level. The exchange\nintegrals of Anderson impurity model were calculated making use of atomic\nHartree-Fock package and angular momentum coupling technique. Theoretical Tc of\nGa0.9375Mn0.0625As obtained in the multiscale ab initio method is in reasonable\nagreement with experiment. The application of Hubbard parameters in DFT\ncalculations using ultrasoft pseudopotentials is discussed.",
        "positive": "Ionization Potentials and Fundamental Gaps in Atomic Systems from the\n  Ensemble-DFT Approach: Calculations in Kohn-Sham density functional theory crucially rely on\nhigh-quality approximations for the exchange-correlation (xc) functional.\nStandard local and semi-local approximations fail to predict the ionization\npotential (IP) and the fundamental gap, departing from the Kohn-Sham orbital\nenergies, due to the deviation of the total energy from piecewise-linearity and\nthe absence of the derivative discontinuity. The ensemble generalization\nprocedure introduced in Phys. Rev. Lett. 110, 126403 (2013) restores, to a\nlarge extent, these features in any approximate xc functional and improves its\nability to predict the IP and the fundamental gap with negligible additional\ncomputational effort. In this work we perform an extensive study of atoms and\nfirst ions across the Periodic Table, generalizing the local spin-density and\nthe Perdew-Burke-Ernzerhof approximations. By applying the ensemble\ngeneralization to a variety of systems, with s-, p- and d-character, we assess\nthe accuracy of the method and identify important trends. In particular, we\nfind that the accuracy of our approach heavily depends on the character of the\nfrontier orbitals: when d-orbitals are involved, the performance is far less\naccurate. Possible sources of error are discussed and ways for further\nimprovement are outlined."
    },
    {
        "anchor": "Disclosing the nature of asymmetric interface magnetism in Co/Pt\n  multilayers: Nowadays a wide number of applications based on magnetic materials relies on\nthe properties arising at the interface between different layers in complex\nheterostructures engineered at the nanoscale. In ferromagnetic/heavy metal\nmultilayers, such as the [Co/Pt]$_N$ and [Co/Pd]$_N$ systems, the magnetic\nproximity effect was demonstrated to be asymmetric, thus inducing a magnetic\nmoment on the Pt(Pd) layer that is typically higher at the top Co/Pt(Pd)\ninterface. In this work, advanced spectroscopic and imaging techniques were\ncombined with theoretical approaches to clarify the origin of this asymmetry\nboth in Co/Pt trilayers and, for the first time, in multilayer systems that are\nmore relevant for practical applications. The different magnetic moment induced\nat the Co/Pt interfaces was correlated to the microstructural features, which\nare in turn affected by the growth processes that induce a different\nintermixing during the film deposition, thus influencing the interface magnetic\nprofile.",
        "positive": "Barium hexaferrite-based nanocomposites as Random Magnets for microwave\n  absorption H: The present work reports experimental evidence of random magnetic behavior\nobserved in modified barium hexagonal ferrites. A significant transition in the\nmagnetic properties of this system is observed when divalent cations (Ni2+,\nCu2+, Mn2+) are introduced in the structure and give rise to a magnetic\nnanocomposite. Such introduction takes place in a random manner throughout each\nsample and creates the conditions for such materials to behave as random\nmagnets. We verify the occurrence of such behavior in our samples by fitting\nthe magnetization in approaching saturation to the corresponding theoretical\nmodel. We therefore analyze the microwave absorption capacities of random\nmagnets in the GHz range and predict large and broad absorption signals under\ncertain conditions. The findings presented here postulate, for the first time,\nceramic materials as promising random magnets and underline their potential as\nmicrowave absorbers, in good agreement with recent theoretical models."
    },
    {
        "anchor": "Interplay between Bonding and Magnetism in the Adsorption of NO on Rh\n  Clusters: We have studied the adsorption of NO on small Rh clusters, containing one to\nfive atoms, using density functional theory in both spin-polarized and\nnon-spin-polarized forms. We find that NO bonds more strongly to Rh clusters\nthan it does to Rh(100) or Rh(111); however, it also quenches the magnetism of\nthe clusters. This (local) effect results in reducing the magnitude of the\nadsorption energy, and also washes out the clear size-dependent trend observed\nin the non-magnetic case. Our results illustrate the competition present\nbetween the tendencies to bond and to magnetize, in small clusters.",
        "positive": "On the origin of red luminescence from iron-doped beta-Ga2O3 bulk\n  crystals: Currently, Fe doping in the ~10^18 cm-3 range is the most widely-available\nmethod for producing semi-insulating single crystalline beta-Ga2O3 substrates.\nRed luminescence features have been reported from multiple types of Ga2O3\nsamples including Fe-doped -Ga2O3, and attributed to Fe or N at O. Herein,\nhowever, we demonstrate that the high-intensity red luminescence from Fe-doped\nbeta-Ga2O3 commercial substrates consisting of two sharp peaks at 689 nm and\n697 nm superimposed on a broader peak centered at 710 nm originates from Cr\nimpurities present at a concentration near 2 ppm. The red emission exhibits\ntwo-fold symmetry, peaks in intensity for excitation near absorption edge,\nseems to compete with Ga2O3 emission at higher excitation energy and appears to\nbe intensified in the presence of Fe. Based on polarized absorption,\nluminescence observations and Tanabe-Sugano diagram analysis, we propose a\nresonant energy transfer of photogenerated carriers in beta-Ga2O3 matrix to\noctahedrally-coordinated Cr3+ to give red luminescence, possibly also\nsensitized by Fe3+."
    },
    {
        "anchor": "A pure state decomposition approach of the mixed dynamic form factor for\n  mapping atomic orbitals: We demonstrate how the mixed dynamic form factor (MDFF) can be interpreted as\na quadratic form. This makes it possible to use matrix diagonalization methods\nto reduce the number of terms that need to be taken into account when\ncalculating the inelastic scattering of electrons in a crystal. It also leads\nin a natural way to a new basis that helps elucidate the underlying physics.\nThe new method is applied to several cases to show its versatility. In\nparticular, predictions are made for directly imaging atomic orbitals in\ncrystals.",
        "positive": "Microemulsification: An Approach for Analytical Determinations: We address a novel method for analytical determinations that combines\nsimplicity, rapidity, low consumption of chemicals, and portability with high\nanalytical performance taking into account parameters such as precision,\nlinearity, robustness, and accuracy. This approach relies on the effect of the\nanalyte content over the Gibbs free energy of dispersions, affecting the\nthermodynamic stabilization of emulsions or Winsor systems to form\nmicroemulsions (MEs). Such phenomenon was expressed by the minimum volume\nfraction of amphiphile required to form microemulsion, which was the analytical\nsignal of the method. The performed studies were: phase behavior, droplet\ndimension by dynamic light scattering, analytical curve, and robustness tests.\nThe reliability of the method was evaluated by determining water in ethanol\nfuels and monoethylene glycol in complex samples of liquefied natural gas. The\ndispersions were composed of water-chlorobenzene (water analysis) and\nwater-oleic acid (monoethylene glycol analysis) with ethanol as the hydrotrope\nphase. The experiments to determine water demonstrated that the analytical\nperformance depends on the composition of ME. The linear range was fairly broad\nwith limits of linearity up to 70.00% water in ethanol. For monoethylene glycol\nin water the linear range was observed throughout the volume fraction of\nanalyte. The natural gas samples provided by the Petrobras exhibited color,\nparticulate material, high ionic strength, and diverse compounds as metals,\ncarboxylic acids, and anions. The method allowed accurate measures bypassing\nsteps such as extraction, preconcentration, and dilution of the sample. In\naddition, the levels of robustness were promising. This parameter was evaluated\nby investigating the effect of (i) deviations in volumetric preparation of the\ndispersions and (ii) changes in temperature over the analyte contents recorded\nby the method."
    },
    {
        "anchor": "Elastic Microplane Formulation for Transversely Isotropic Materials: This contribution investigates the extension of the microplane formulation to\nthe description of transversely isotropic materials such as shale rock, foams,\nunidirectional composites, and ceramics. Two possible approaches are\nconsidered: 1) the spectral decomposition of the stiffness tensor to define the\nmicroplane constitutive laws in terms of energetically orthogonal eigenstrains\nand eigenstresses; and 2) the definition of orientation-dependent microplane\nelastic moduli. It is shown that the first approach provides a rigorous way to\ntackle anisotropy within the microplane framework whereas the second approach\nrepresents an approximation which, however, makes the formulation of nonlinear\nconstitutive equations much simpler. The efficacy of the second approach in\nmodeling the macroscopic elastic behavior is compared to the thermodynamic\nrestrictions of the anisotropic parameters showing that a significant range of\nelastic properties can be modeled with excellent accuracy. Further, it is shown\nthat it provides a very good approximation of the microplane stresses provided\nby the first approach, with the advantage of a simpler formulation.\n  It is concluded that the spectral stiffness decomposition represents the best\napproach in such cases as for modeling unidirectional composites, in which\naccurately capturing the elastic behavior is important. The introduction of\norientation-dependent microplane elastic moduli provides a simpler framework\nfor the modeling of transversely isotropic materials with remarked inelastic\nbehavior, as in the case, for example, of shale rock.",
        "positive": "Single Crystalline InGaAs Nanopillar Grown on Polysilicon with\n  Dimensions beyond Substrate Grain Size Limit: Monolithic integration of III-V optoelectronic devices with materials for\nvarious functionalities inexpensively is always desirable. Polysilicon\n(poly-Si) is an ideal platform because it is dopable and semi-conducting and\ncan be deposited and patterned easily on a wide range of low cost substrates.\nHowever, the lack of crystalline coherency in poly-Si poses an immense\nchallenge for high-quality epitaxial growth. In this work, we demonstrate, for\nthe first time, direct growth of micron-sized InGaAs/GaAs nanopillars on\npolysilicon. Transmission electron microscopy shows that the micron-sized\npillars are single-crystalline and single Wurzite-phase, far exceeding the\nsubstrate crystal grain size ~100nm. The high quality growth is enabled by the\nunique tapering geometry at the base of the nanostructure, which reduces the\neffective InGaAs/Si contact area to < 40 nm in diameter. The small footprint\nnot only reduces stress due to lattice mismatch but also prevents the\nnanopillar from nucleating on multiple Si crystal grains. This relaxes the\ngrain size requirement for poly-Si, potentially reducing the cost for poly-Si\ndeposition. Lasing is achieved in the as-grown pillars under optical pumping,\nattesting their excellent crystalline and optical quality. These promising\nresults open up a pathway for low-cost synergy of optoelectronics with other\ntechnologies such as CMOS integrated circuits, sensing, nanofluidics, thin film\ntransistor display, photovoltaics, etc."
    },
    {
        "anchor": "Interconversion of multiferroic domains and domain walls: Materials with long-range order like ferromagnetism or ferroelectricity\nexhibit uniform, yet differently oriented three-dimensional regions called\ndomains that are separated by two-dimensional topological defects termed domain\nwalls\\cite{Tagantsev2010,AlexHubert1998}. A change of the ordered state across\na domain wall can lead to local non-bulk properties such as enhanced\nconductance or the promotion of unusual\nphases\\cite{Seidel2009,Meier2012,Farokhipoor2014}. Although highly desirable,\ncontrolled transfer of these exciting properties between the bulk and the walls\nis usually not possible. Here we demonstrate this crossover from three- to\ntwo-dimensions for confining multiferroic Dy$_{0.7}$Tb$_{0.3}$FeO$_3$ domains\ninto multiferroic domain walls at a specified location within a\nnon-multiferroic environment. This process is fully reversible; an applied\nmagnetic or electric field controls the transformation. Aside from the aspect\nof magnetoelectric functionality, such interconversion can be key to tailoring\nelusive domain architectures such as in antiferromagnets.",
        "positive": "Optical transitions in broken gap heterostructures: We have used an eight band model to investigate the electronic structures and\nto calculate the optical matrix elements of InAs-GaSb broken gap semiconductor\nheterostructures. The unusual hybridization of the conduction band states in\nInAs layers with the valence band states in GaSb layers has been analyzed in\ndetails. We have studied the dependence of optical matrix elements on the\ndegree of conduction-valence hybridization, the tuning of hybridization by\nvarying the width of the GaSb layers and/or InAs layers, and the sensitivity of\nquantized levels to this tuning. Large spin-orbit splitting in energy bands has\nbeen demonstrated. Our calculation can serve as a theoretical modeling for\ninfrared lasers based on broken gap quantum well heterostructures."
    },
    {
        "anchor": "The influence of silicon on the formation and transformation of\n  corrosion products: Accurate model predictions of corrosion-driven damage in reinforced concrete\nstructures necessitate a comprehensive understanding of the rate of corrosion\nproduct formation. Here, we investigate the influence of dissolved Si\ncharacteristic of cementitious systems on the rate of corrosion product\ntransformation at alkaline pH. Compared to systems aged in the absence of Si,\nsmall amounts of Si retard the formation rate of the thermodynamically stable\ncorrosion product goethite by a factor of 10. The estimated first order rate\nconstant of transformation k decreases exponentially as a function of the\ndissolved Si concentration and follows the progression log10k = log10k_0 -\n14.65[Si]^0.28. Findings further suggest that the observed retardation is\nprimarily due to the formation of a mobile aqueous Fe-Si complex. The\nconcentration of Si in cementitious systems has a crucial influence, and\nadditional research is required to fully incorporate this factor into reactive\ntransport models, ultimately essential for accurate service life predictions.",
        "positive": "Freeze-Casting of Porous Ceramics: A Review of Current Achievements and\n  Issues: Freeze-casting, the templating of porous structure by the solidification of a\nsolvent, have seen a great deal of efforts during the last few years. Of\nparticular interest are the unique structure and properties exhibited by porous\nfreeze-casted ceramics, which opened new opportunities in the field of cellular\nceramics. The objective of this review is to provide a first understanding of\nthe process as of today, with particular attention being paid on the underlying\nprinciples of the structure formation mechanisms and the influence of\nprocessing parameters on the structure. This analysis highlights the current\nlimits of both the understanding and the control of the process. A few\nperspectives are given, with regards of the current achievements, interests and\nidentified issues."
    },
    {
        "anchor": "Coexistance of giant tunneling electroresistance and magnetoresistance\n  in an all-oxide magnetic tunnel junction: We demonstrate with first-principles electron transport calculations that\nlarge tunneling magnetoresistance (TMR) and tunneling electroresistance (TER)\neffects can coexist in an all-oxide device. The TMR originates from the\nsymmetry-driven spin filtering provided by the insulating BaTiO3 barrier to the\nelectrons injected from SrRuO3. In contrast the TER is possible only when a\nthin SrTiO3 layer is intercalated at one of the SrRuO3/BaTiO3 interfaces. As\nthe complex band-structure of SrTiO3 has the same symmetry than that of BaTiO3,\nthe inclusion of such an intercalated layer does not negatively alter the TMR\nand in fact increases it. Crucially, the magnitude of the TER also scales with\nthe thickness of the SrTiO3 layer. The SrTiO3 thickness becomes then a single\ncontrol parameter for both the TMR and the TER effect. This protocol offers a\npractical way to the fabrication of four-state memory cells.",
        "positive": "Impact of substrate on magnetic phase coexistence in bicritical\n  $Sm_{0.53} Sr_{0.47} Mn O_3$ thin films: Sm0.53Sr0.47MnO3 thin films were deposited on single crystal LaAlO3\n(LAO/(001)) and SrTiO3 (STO/(001)) substrates by DC magnetron sputtering. The\ntheta-2theta and omega-2theta scans show that these films have very good\ncrystallinity and the films on LAO and STO are under compressive and tensile\nstrain, respectively. The films on LAO and STO substrates show ferromagnetic\n(insulator-metal) transition at TC \\sim 126 K (at TIM \\sim 128 K) and 120 K\n(TIM \\sim 117K), respectively. The magnetic state at T<TC is akin to cluster\nglass, which is formed by the presence of charge ordered-antiferromagnetic\nclusters in the ferromagnetic matrix. Huge drop in the resistivity at TIM and\nthe associated hysteresis with respect to cooling and warming cycles reveal the\nbicritical and the first order nature of phase transition, which is also\nconfirmed by the Banerjee criterion. The differences and similarities in the\nfunctional properties of films are explained in terms of substrate modified\nmagnetic phase coexistence."
    },
    {
        "anchor": "DFT based investigation of bulk mechanical, thermophysical and\n  optoelectronic properties of PbTaSe2 topological semimetal: PbTaSe2 is a non-centrosymmetric topological semimetal. In this work we have\nexplored the structural, elastic, mechanical, bonding, electronic, acoustic,\nthermal, and optical properties of PbTaSe2. The electronic bond structure\ncalculations confirm semi-metallic character. Fermi surface topology shows both\nelectron and hole sheets. The single crystal elastic constants reveal that\nPbTaSe2 is elastically stable. The compound is soft, brittle, and highly\nmachinable at the same time. It also possesses very high level of dry\nlubricity. Various anisotropy indicators suggest that PbTaSe2 is elastically\nanisotropic with layered character. The phonon dynamics has been investigated.\nPhonon dispersion plot shows that the compound is dynamically stable with a\nclear frequency gap between the acoustic and optical branches. The Debye\ntemperature, phonon thermal conductivity, and melting temperature of PbTaSe2 is\nlow. The compound has medium Gr\\\"uneisen parameter. The bonding character is\nmainly dominated by ionic bonding with some metallic contribution. The optical\nparameters have been studied in detail. The optical spectra reveal metallic\nfeatures. The compound reflects visible light very efficiently (reflectance\nabove 60%). It is also an efficient absorber of the ultraviolet light. The\ncompound exhibits significant optical anisotropy with respect to the\npolarization directions of the incident electric field.",
        "positive": "Molecular dynamics study of electronic temperature effects on the laser\n  ablation of silicon: The molecular dynamics (MD) approach is an effective tool for investigating\natomistic dynamical phenomena at the surface of materials under strong laser\nirradiation. Therefore, numerous laser ablation MD simulation studies have been\nconducted to date. However, in most MD studies, non-thermal and entropic\neffects via hot electrons on interatomic interactions that could cause\nsignificant differences in the simulation results are not considered. In this\nstudy, the MD simulation of the laser ablation of the Si surface was conducted\nusing an interatomic potential whose parameters depended on the electronic\ntemperature. Moreover, the results obtained with and without electronic\ntemperature dependence were compared. The electronic temperature dependence\nresulted in an approximately four-times-greater compressive pressure near the\nsurface, enhanced evaporation of atomic or smaller clusters, and slightly\nlonger melt depth. Compared to the strong compressive pressure near the\nsurface, the tensile pressure, which originated from the reflection of the\ncompressive pressure wave at the surface, and ablation phenomena were less\ndependent on the electronic temperature."
    },
    {
        "anchor": "Magnetism and Magnetic Anisotropy of Transition Metal-Phthalocyanine\n  Molecules: Search for single-molecule magnets (SMMs) with high blocking temperature (TB)\nis urgent for practical applications in magnetic recording, molecular\nspintronics and quantum computing. Based on the First-principles calculations,\nmagnetic anisotropy energies (MAE) of the transition metal-Phthalocyanine\n(TM-Pc) molecules are investigated and the mechanism that determines the MAE of\nTM-Pc molecules is established. In particular, colossal MAE > 100 meV can be\nobtained by adding an Os atom on RuPc and OsPc, so these molecules may offer\nultrahigh thermal stability in devices.",
        "positive": "Asymmetric Spin-wave Dispersion on Fe(110): Direct Evidence of\n  Dzyaloshinskii--Moriya Interaction: The influence of the Dzyaloshinskii-Moriya interaction on the spin-wave\ndispersion in an Fe double layer grown on W(110) is measured for the first\ntime. It is demonstrated that the Dzyaloshinskii-Moriya interaction breaks the\ndegeneracy of spin waves and leads to an asymmetric spin-wave dispersion\nrelation. An extended Heisenberg spin Hamiltonian is employed to obtain the\nlongitudinal component of the Dzyaloshinskii-Moriya vectors from the\nexperimentally measured energy asymmetry."
    },
    {
        "anchor": "Thermal rectification of a single-wall carbon nanotube: a molecular\n  dynamics study: We have investigated the thermal rectification phenomenon in a single-wall\nmass graded carbon nanotube by molecular dynamics simulation. Second generation\nBrenner potential has been used to model the inter atomic carbon interaction.\nFixed boundary condition has been taken into account. We compare our findings\nto a previous study by Alaghemandi et al which has been done with a different\npotential and boundary condition. The dependence of the rectification factor\n$R$ on temperature, nanotube diameter and length as well as mass gradient are\nobtained. It is shown that by increasing the temperature, the rectification\ndecreases whereas by increasing the other parameters namely the mass gradient,\ndiameter and the tube length it increases.",
        "positive": "Temperature dependence of linewidth in nano-contact based spin torque\n  oscillators: effect of multiple oscillatory modes: We discuss the effect of mode transitions on the current (I) and temperature\n(T) dependent linewidth (\\Delta f) in nanocontact based spin torque oscillators\n(STOs). At constant I, \\Delta f exhibits an anomalous temperature dependence\nnear the mode transitions; \\Delta f may either increase or decrease with T\ndepending on the position w.r.t. the mode transition. We show that the behavior\nof \\Delta f as a function of I can be fitted by the single mode analytical\ntheory of STOs, even though there are two modes present near the mode\ntransition, if the nonlinear amplification is determined directly from the\nexperiment. Using a recently developed theory of two coupled modes, we show\nthat the linewidth near mode transition can be described by an \"effective\"\nsingle-oscillator theory with an enhanced nonlinear amplification that carries\nadditional temperature dependence, which thus qualitatively explain the\nexperimental results."
    },
    {
        "anchor": "Heat flux sensing by anomalous Nernst effect in Fe-Al thin films on a\n  flexible substrate: We performed a numerical analysis of the material parameters required for\nrealizing a heat flux sensor exploiting the anomalous Nernst effect (ANE). The\nresults showed the importance of high thermopower of ANE ($S_{\\text{ANE}}$) and\nsmall saturation magnetization. This motivated us to investigate the effect of\nAl substitution of Fe on ANE and found $S_{\\text{ANE}} =$ 3.4 $\\mu$V/K in\nFe$_{81}$Al$_{19}$ because of the dominant intrinsic mechanism. Using this\nmaterial, we made a prototype ANE-based heat flux sensor on a thin flexible\npolyimide sheet and demonstrated accurate sensing with it. This study gives\nimportant information for enhancing sensor sensitivity.",
        "positive": "Pressure-induced phase transition of Bi2Te3 into the bcc structure: The pressure-induced phase transition of bismuth telluride, Bi2Te3, has been\nstudied by synchrotron x-ray diffraction measurements at room temperature using\na diamond-anvil cell (DAC) with loading pressures up to 29.8 GPa. We found a\nhigh-pressure body-centered cubic (bcc) phase in Bi2Te3 at 25.2 GPa, which is\ndenoted as phase IV, and this phase apperars above 14.5 GPa. Upon releasing the\npressure from 29.8 GPa, the diffraction pattern changes with pressure\nhysteresis. The original rhombohedral phase is recovered at 2.43 GPa. The bcc\nstructure can explain the phase IV peaks. We assumed that the structural model\nof phase IV is analogous to a substitutional binary alloy; the Bi and Te atoms\nare distributed in the bcc-lattice sites with space group Im-3m. The results of\nRietveld analysis based on this model agree well with both the experimental\ndata and calculated results. Therefore, the structure of phase IV in Bi2Te3 can\nbe explained by a solid solution with a bcc lattice in the Bi-Te (60 atomic%\ntellurium) binary system."
    },
    {
        "anchor": "Anisotropy of Thermal Conductivity of Free-Standing Reduced Graphene\n  Oxide Films Annealed at High Temperature: We investigated thermal conductivity of free-standing reduced graphene oxide\nfilms subjected to a high-temperature treatment of up to 1000 C. It was found\nthat the high-temperature annealing dramatically increased the in-plane thermal\nconductivity, K, of the films from 3 W/mK to 61 W/mK at room temperature. The\ncross-plane thermal conductivity, Kc, revealed an interesting opposite trend of\ndecreasing to a very small value of 0.09 W/mK in the reduced graphene oxide\nfilms annealed at 1000 C. The obtained films demonstrated an exceptionally\nstrong anisotropy of the thermal conductivity, K/Kc ~ 675, which is\nsubstantially larger even than in the high-quality graphite. The electrical\nresistivity of the annealed films reduced to 1 - 19 Ohms/sq. The observed\nmodifications of the in-plane and cross-plane thermal conductivity components\nresulting in an unusual K/Kc anisotropy were explained theoretically. The\ntheoretical analysis suggests that K can reach as high as ~500 W/mK with the\nincrease in the sp2 domain size and further reduction of the oxygen content.\nThe strongly anisotropic heat conduction properties of these films can be\nuseful for applications in thermal management.",
        "positive": "Transient and self-limited nanostructures on patterned surfaces: Site-controlled quantum dots formed during the deposition of (Al)GaAs layers\nby metalorganic vapor-phase epitaxy on GaAs(111)B substrates patterned with\ninverted pyramids result in geometric and compositional self-ordering along the\nvertical axis of the template. We describe a theoretical scheme that reproduces\nthe experimentally-observed time-dependent behavior of this process, including\nthe evolution of the recess and the increase of Ga incorporation along the base\nof the template to stationary values determined by alloy composition and other\ngrowth parameters. Our work clarifies the interplay between kinetics and\ngeometry for the development of self-ordered nanostructures on patterned\nsurfaces, which is essential for the reliable on-demand design of confined\nsystems for applications to quantum optics."
    },
    {
        "anchor": "Far infrared and terahertz spectroscopy of ferroelectric soft modes in\n  thin films: A review: Far-infrared and terahertz spectroscopy of ferroelectric soft and central\nmodes in thin films on substrates is reviewed. In addition to classical\ndisplacive proper ferroelectrics, also incipient and relaxor ferroelectrics and\nmultiferroics are discussed. Special attention is paid to differences between\nthe soft-mode behavior in thin films and bulk materials (ceramics and single\ncrystals) and their influence on the low-frequency permittivity. Particularly\nthe effects of the thin film strains and depolarizing electric fields of the\nprobing waves on the grain boundaries are emphasized. The soft-mode\nspectroscopy is shown to be a very sensitive tool to reveal the thin film\nquality.",
        "positive": "Electronic states in ideal free standing films: Exact and general results on the electronic states in ideal free standing\nfilms are presented. In many interesting cases, such as in FCC (001) films and\nin FCC (110) films, the energies of most electronic states in the film can be\nanalytically obained from the corresponding energy band structure of the bulk.\nThis approach can be further extended to obtain exact and general results on\nthe electronic states in quantum wires and quantum dots."
    },
    {
        "anchor": "Ab initio electron-phonon interactions in correlated electron systems: Electron-phonon ($e$-ph) interactions are pervasive in condensed matter,\ngoverning phenomena such as transport, superconductivity, charge-density waves,\npolarons and metal-insulator transitions. First-principles approaches enable\naccurate calculations of $e$-ph interactions in a wide range of solids.\nHowever, they remain an open challenge in correlated electron systems (CES),\nwhere density functional theory often fails to describe the ground state.\nTherefore reliable $e$-ph calculations remain out of reach for many transition\nmetal oxides, high-temperature superconductors, Mott insulators, planetary\nmaterials and multiferroics. Here we show first-principles calculations of\n$e$-ph interactions in CES, using the framework of Hubbard-corrected density\nfunctional theory (DFT+$U$ ) and its linear response extension (DFPT+$U$),\nwhich can describe the electronic structure and lattice dynamics of many CES.\nWe showcase the accuracy of this approach for a prototypical Mott system, CoO,\ncarrying out a detailed investigation of its $e$-ph interactions and electron\nspectral functions. While standard DFPT gives unphysically divergent and\nshort-ranged $e$-ph interactions, DFPT+$U$ is shown to remove the divergences\nand properly account for the long-range Fr\\\"ohlich interaction, allowing us to\nmodel polaron effects in a Mott insulator. Our work establishes a broadly\napplicable and affordable approach for quantitative studies of e-ph\ninteractions in CES, a novel theoretical tool to interpret experiments in this\nbroad class of materials.",
        "positive": "Solution calorimetry investigations of new phase BaCe0.6Y0.3In0.1O2.8: The preparation of BaCeO3 doped by yttrium and indium oxides\n(BaCe0.6Y0.3In0.1O2.8) has been performed by solid-state reaction from BaCO3,\nCeO2, Y2O3, In2O3. The compound BaCe0.6Y0.3In0.1O2.8 has been synthesized for\nthe first time. The X-ray measurements have showed that BaCe0.6Y0.3In0.1O2.8\nhas an orthorhombic structure (space group Pmcn). The standard formation\nenthalpies of BaCe0.6Y0.3In0.1O2.8 have been determined by solution calorimetry\ncombining the solution enthalpies of BaCe0.6Y0.3In0.1O2.8 and BaCl2 + 0.6CeCl3\n+ 0.3YCl3 + 0.1InCl3 mixtures in 1 M HCl with 0.1 M KI at 298.15 K and\nliterature data. It has been obtained that above-mentioned mixed oxide is\nthermodynamically stable with respect to their decomposition into binary oxides\nat room temperatures. It has been also shown that BaCe0.6Y0.3In0.1O2.8 has been\nmore thermodynamically favored than BaCe0.9In0.1O2.95."
    },
    {
        "anchor": "Enhancement of polarization and magnetization in polycrystalline\n  magnetoelectric composite: Electrical control of magnetization or magnetic control of polarization\noffers an extra degree of freedom in materials possessing both electric and\nmagnetic dipole moments viz., magnetoelectric multiferroics. Microstructure\nwith polycrystalline configurations that enhances the overall\npolarization/magnetization and that outperform single crystalline\nconfigurations are identified. The characterization of local fields\ncorresponding to the polycrystal configuration underlines nontrivial role\nplayed by randomness in better cross-coupling mediated by anisotropic and\nasymmetric strains.",
        "positive": "Revisiting the stable structure of the Cu$_{4}$ complex in silicon: The photoluminescence (PL) spectrum of Cu-containing silicon has a sharp\nzero-phonon (ZP) band at 1.014 eV. The luminescence center corresponding to\nthis band is called Cu$_{PL}$ and is known to have the local $C_{3v}$ symmetry.\nA recent measurement by ultrahigh-resolution PL spectroscopy revealed that the\nCu$_{PL}$ center is a Cu$_{4}$ complex. Later, it was shown, by\nfirst-principles calculations, that the structure was Cu$_{(s)}$Cu$_{3(i)}$,\nthat is, a complex composed of three interstitial Cu$_{(i)}$ atoms around a\nsubstitutional Cu$_{(s)}$ atom. This complex (called $C$-type) has the desired\nsymmetry. However, in this study, we show that the lowest-energy structure is\ndifferent. The tetrahedral structure Cu$_{4}$, called $T$-type, has the lowest\nenergy, with the value being 0.26 eV lower than that of $C$-type. Between these\ntwo types, there is an energy barrier of 0.14 eV, which allows $C$-type to\nexist in a metastable state. Details of the electronic properties of the\n$T$-type complex are given, by comparing with $C$-type and other isovalent\ncomplexes such as Li$_{4}$. Whereas the Cu$_{4}$ tetrahedron is incorporated in\nsilicon in a manner compatible with the tetrahedral network, it also has its\nown molecular orbitals that exhibit metallic characteristics, in contrast to\nother complexes. The ZP of the PL spectrum is very likely ascribed to the\nbackflow mode of the Cu$_{4}$ tetrahedron."
    },
    {
        "anchor": "Metal-insulator transition in electric field: A viewpoint from the\n  switching effect: The proposed switching mechanism is based on an electronically-induced\nmetal-insulator transition occurring in conditions of the excess\nnon-equilibrium carrier density under the applied electric field. First, this\nmechanism is developed on the basis of a phenomenological approach. This model\nnot only allows the qualitative description of the switching mechanism, but it\nis in quantitative agreement with the experimental results, in particular, with\nthose concerning the critical concentration and threshold field. The mechanism\ntakes into account the dependence of the carrier density on electric field, as\nwell as the scaling of the critical field. Next, we show that such a\n'macroscopic' approach can be supported by some microscopic model. The\nquintessence of this approach consists in the fact that an electronically\ninduced metal-insulator transition may be described in terms of\nBardeen-Cooper-Schrieffer (BCS) formalism developed earlier for the charge\ndensity wave concept. It is shown that for the combination of both the types of\ninteraction (electron-electron and electron-phonon), the formation of a\ncollective excitation - an electron crystal of charge density wave - in the\nmodel of exciton insulator is possible, which, in a general case, can also be\naccompanied by a structural transition. The results for vanadium dioxide are\nexamined within the frameworks of the developed approach.",
        "positive": "Large Thermoelectric Power Factor in TiS2 Crystal with Nearly\n  Stoichiometric Composition: A TiS$_{2}$ crystal with a layered structure was found to have a large\nthermoelectric power factor.The in-plane power factor $S^{2}/ \\rho$ at 300 K is\n37.1~$\\mu$W/K$^{2}$cm with resistivity ($\\rho$) of 1.7 m$\\Omega$cm and\nthermopower ($S$) of -251~$\\mu$V/K, and this value is comparable to that of the\nbest thermoelectric material, Bi$_{2}$Te$_{3}$ alloy. The electrical\nresistivity shows both metallic and highly anisotropic behaviors, suggesting\nthat the electronic structure of this TiS$_{2}$ crystal has a\nquasi-two-dimensional nature. The large thermoelectric response can be ascribed\nto the large density of state just above the Fermi energy and inter-valley\nscattering. In spite of the large power factor, the figure of merit, $ZT$ of\nTiS$_{2}$ is 0.16 at 300 K, because of relatively large thermal conductivity,\n68~mW/Kcm. However, most of this value comes from reducible lattice\ncontribution. Thus, $ZT$ can be improved by reducing lattice thermal\nconductivity, e.g., by introducing a rattling unit into the inter-layer sites."
    },
    {
        "anchor": "Size and polydispersity effect on the magnetization of densely packed\n  magnetic nanoparticles: The magnetic properties of densely packed magnetic nanoparticles (MNP)\nassemblies are investigated from Monte Carlo simulations. The case of iron\noxide nanoparticles is considered as a typical example of MNP. The main focus\nis put on particle size and size polydispersity influences on the magnetization\ncurve. The particles are modeled as uniformly magnetized spheres isolated one\nfrom each other by a non magnetic layer representing the organic coating. A\ncomparison with recent experimental results on $\\gamma-$Fe$_2$O$_3$ powder\nsamples differing by their size is given.",
        "positive": "Theory of volumetric capacitance of an electric double-layer\n  supercapacitor: Electric double layer supercapacitors are a fast-rising class of high-power\nenergy storage devices based on porous electrodes immersed in a concentrated\nelectrolyte or ionic liquid. As of yet there is no microscopic theory to\ndescribe their surprisingly large capacitance per unit volume (volumetric\ncapacitance) of ~ 100 F/cm^3, nor is there a good understanding of the\nfundamental limits on volumetric capacitance. In this paper we present a\nnon-mean-field theory of the volumetric capacitance of a supercapacitor that\ncaptures the discrete nature of the ions and the exponential screening of their\nrepulsive interaction by the electrode. We consider analytically and via\nMonte-Carlo simulations the case of an electrode made from a good metal and\nshow that in this case the volumetric capacitance can reach the record values.\nWe also study how the capacitance is reduced when the electrode is an imperfect\nmetal characterized by some finite screening radius. Finally, we argue that a\ncarbon electrode, despite its relatively large linear screening radius, can be\napproximated as a perfect metal because of its strong nonlinear screening. In\nthis way the experimentally-measured capacitance values of ~ 100 F/cm^3 may be\nunderstood."
    },
    {
        "anchor": "New Superhard Phases for 3D C60-based Fullerites: We have explored new possible phases of 3D C60-based fullerites using\nsemiempirical potentials and ab-initio density functional methods. We have\nfound three closely related structures - two body centered orthorhombic and one\nbody centered cubic - having 52, 56 and 60 tetracoordinated atoms per molecule.\nThese 3D polymers result in semiconductors with bulk moduli near 300 GPa, and\nshear moduli around 240 GPa, which make them good candidates for new low\ndensity superhard materials.",
        "positive": "Nonlinear Ionic Conductivity of Thin Solid Electrolyte Samples:\n  Comparison between Theory and Experiment: Nonlinear conductivity effects are studied experimentally and theoretically\nfor thin samples of disordered ionic conductors. Following previous work in\nthis field the {\\it experimental nonlinear conductivity} of sodium ion\nconducting glasses is analyzed in terms of apparent hopping distances. Values\nup to 43 \\AA are obtained. Due to higher-order harmonic current density\ndetection, any undesired effects arising from Joule heating can be excluded.\nAdditionally, the influence of temperature and sample thickness on the\nnonlinearity is explored. From the {\\it theoretical side} the nonlinear\nconductivity in a disordered hopping model is analyzed numerically. For the 1D\ncase the nonlinearity can be even handled analytically. Surprisingly, for this\nmodel the apparent hopping distance scales with the system size. This result\nshows that in general the nonlinear conductivity cannot be interpreted in terms\nof apparent hopping distances. Possible extensions of the model are discussed."
    },
    {
        "anchor": "Direct imaging of current-induced antiferromagnetic switching revealing\n  a pure thermomagnetoelastic switching mechanism: We unravel the origin of current-induced magnetic switching of insulating\nantiferromagnet/heavy metal systems. We utilize concurrent transport and\nmagneto-optical measurements to image the switching of antiferromagnetic\ndomains in specially engineered devices of NiO/Pt bilayers. Different\nelectrical pulsing and device geometries reveal different final states of the\nswitching with respect to the current direction. We can explain these through\nsimulations of the temperature induced strain and we identify the\nthermomagnetoelastic switching mechanism combined with thermal excitations as\nthe origin, in which the final state is defined by the strain distributions and\nheat is required to switch the antiferromagnetic domains. We show that such a\npotentially very versatile non-contact mechanism can explain the previously\nreported contradicting observations of the switching final state, which were\nattributed to spin-orbit torque mechanisms.",
        "positive": "Enhanced ferrimagnetism in auxetic NiFe2O4 in the crossover to the\n  ultrathin film limit: We investigate the sensitive interplay between magnetic, electronic and\nstructural properties in the ferrimagnetic oxide NiFe2O4. Emphasis is placed on\nthe impact of reduced dimensionality in the crossover from bulk-like to\nultrathin films. We observed an enhanced saturation magnetization $M_S$ for\nultrathin NiFe2O4 films on Nb-SrTiO3 (001) substrates that co-occurs with a\nreduced out-of-plane lattice constant under compressive in-plane epitaxial\nstrain. We found a bulk-like cationic coordination of the inverse spinel\nlattice independent of the NiFe2O4 film thickness -- thus ruling out a cationic\ninversion that nominally could account for an enhanced $M_S$. Our study instead\nuncovers a reduction of the unit cell volume, i.e. an auxetic behavior in\nultrathin NiFe2O4 films, which may result in an enhanced magnetic exchange\ncaused by an increased interatomic electronic localization."
    },
    {
        "anchor": "Evolution of Intrinsic Vacancies and Prolonged Lifetime of Vacancy\n  Clusters in Black Phosphorene: Due to the relatively low formation energies and highly mobile\ncharacteristics of atomic vacancies in phosphorene, understanding their\nevolutions becomes crucial for its structural integrity, chemical activities\nand applications. Herein, by combining first-principles calculations and\nkinetic Monte Carlo simulation, we investigate the time evolution and formation\nof atomic vacancy clusters from isolated monovacancies (MVs), aiming to uncover\nthe mechanisms of diffusion, annihilation, reaction of these atomic vacancies.\nWe find that while isolated MVs possess a highly mobile character, they react\nand form MV pairs which possess much lower mobility and high stability under\nambient condition. We also show that the disappearance of MVs at the edge is\nquite slow due to the relatively high energy barrier, and as a result, around\n80% of MVs remains even after two years under ambient condition. Our findings\non one hand provide useful information for the structural repairing of\nphosphorene through chemical functionalization of these vacancy clusters, and\non the other hand, suggest that these rather stable vacancy clusters may be\nused as an activated catalyst.",
        "positive": "Topological spiral magnetism in the Weyl semimetal SmAlSi: Weyl electrons are intensely studied due to novel charge transport phenomena\nsuch as chiral anomaly, Fermi arcs, and photogalvanic effect. Recent\ntheoretical works suggest that Weyl electrons can also participate in magnetic\ninteractions, and the Weyl-mediated indirect exchange coupling between local\nmoments is proposed as a new mechanism of spiral magnetism that involves chiral\nelectrons. Despite reports of incommensurate and non-collinear magnetic\nordering in Weyl semimetals, an actual spiral order has remained hitherto\nundetected. Here, we present evidence of Weyl-mediated spiral magnetism in\nSmAlSi from neutron diffraction, transport, and thermodynamic data. We show\nthat the spiral order in SmAlSi results from the nesting between topologically\nnon-trivial Fermi pockets and weak magnetocrystalline anisotropy, unlike\nrelated materials (Ce,Pr,Nd)AlSi, where a strong anisotropy prevents the spins\nfrom freely rotating. We map the magnetic phase diagram of SmAlSi and reveal an\nA-phase where topological magnetic excitations may exist. This is corroborated\nby the observation of a topological Hall effect within the A-phase."
    },
    {
        "anchor": "A Theoretical and Computational Study of H$_2$ Physisorption on Covalent\n  Organic Framework Linkers and Metalated Linkers: A Strategy to Enhance\n  Binding Strength: Hydrogen is deemed as an attractive energy carrier alternative to fossil\nfuels, and it is required to store for many applications. Physisorption is one\nof the promising ways to store H$_2$ for its practical applications. Covalent\nOrganic Frameworks (COFs) are promising candidates for H$_2$-storage due to\nhigh porosity, surface area and tunable characteristics. To improve the\nhydrogen physisorption in the COFs, the chelation of transition metals (TM) in\nthe building blocks of the framework has been studied by using first\nprinciple-based density functional theory (DFT) method. Here, we report total\n96 H$_2$ complexes made of six different COF linkers and chelated with the Sc,\nTi and V atoms interacting with up to H$_2$ molecules. The molecular\ninteractions between physisorption H$_2$ and these Sc-, Ti- and V-chelated\nlinkers have been explored in detail. The binding enthalpy of the most\ncomplexes is higher than ~10 kJ/mol, which is the basic requirement for\npractical H$_2$-storage. In the total interaction energy (between physisorption\nH$_2$ and chelated linkers), the dispersion and electrostatic interactions are\ndominant. This study is essential in finding out the more efficient COF linkers\nfor practical H$_2$ storage. It can also help to improve the uptake of existing\nporous materials for H$_2$ storage. The present study paves a way to design\ntransition metal chelated COFs for an effective H$_2$-storage and the knowledge\ngained from this study is expected to provide some inspiration for developing\nthe corresponding experiments.",
        "positive": "Kinetics of Charge Transport in Wide-Band Semiconductors at the\n  Detection of X-Ray Radiation: As a result of absorption of X-ray quantum in a semiconductor, the generation\nof electron-hole pairs takes place in a small volume (diameter < 0.5 mkm).\nTheir surplus energy is lost due to the scattering on phonons of the crystal\nlattice. Spatial distribution of the charge carriers makes the form of current\npulse on electrodes of the crystal complicated when an external electric field\nis applied. We present a logical chart of construction of basic kinetic model\nof X-ray conductivity in semiconductors that uses the successive in time\ncalculation of the spatial distribution of free charge arriers and the\ndiffusive-drift model of motion of free carriers in a solid. The basic form of\ncurrent pulse in an external circle was obtained in the analytical kind for the\ncase of an ideal semiconductor, e.g. that does not contain deep traps and\nrecombination centers, as well as for the case of a crystal with dominant\nshallow or deep traps of electrons and holes."
    },
    {
        "anchor": "Correlated Doping in Semiconductors: The Role of Donors in III-V Diluted\n  Magnetic Semiconductors: We investigate the compositional dependence of the total energy of the mixed\ncrystals (Ga,Mn)As co-doped with As, Sn, and Zn. Using the ab initio LMTO-CPA\nmethod we find a correlation between the incorporation of acceptors (Mn, Zn)\nand donors (Sn, antisite As). In particular, the formation energy of As_Ga is\nreduced by approx. 0.1 eV in the presence of Mn, and vice versa. This leads to\nthe self-compensating behavior of (Ga,Mn)As.",
        "positive": "Electronic and Structural Properties of C$_{36}$ Molecule: The extended SSH model and Bogoliubov-de Gennes(BdeG) formalism are applied\nto investigate the electronic properties and stable lattice configurations of\nC$_{36}$. We focus the problem on the molecule's unusual $D_{6h}$ symmetry. The\nelectronic part of the Hamiltonian without Coulomb interaction is solved\nanalytically. We find that the gap between HOMO and LUMO is small due to the\nlong distance hopping between the 2nd and 5th layers. The charge densities of\nHOMO and LUMO are mainly distributed in the two layers, that causes a large\nsplitting between the spin triplet and singlet excitons. The differences of\nbond lengths, angles and charge densities among the molecule and polarons are\ndiscussed."
    },
    {
        "anchor": "Transcending the MAX phases concept of nanolaminated early transition\n  metal carbides/nitrides -- the ZIA phases: A new potential class of nanolaminated and structurally complex materials,\nherein conceived as the Zigzag IntermetAllic (ZIA) phases, is proposed. A study\nof the constituent phases of a specific Nb--Si--Ni intermetallic alloy revealed\nthat its ternary H-phase, \\textit{i.e.}, the Nb$_3$SiNi$_2$ intermetallic\ncompound (IMC), is a crystalline solid with the close-packed \\textit{fcc}\nBravais lattice, the 312 MAX phase stoichiometry and a layered atomic\narrangement that may define an entire class of nanolaminated IMCs analogous to\nthe nanolaminated ceramic compounds known today as the MAX phases. The electron\nmicroscopy investigation of the Nb$_{3}$SiNi$_{2}$ compound -- the first\ncandidate ZIA phase -- revealed a remarkable structural complexity, as its\nordered unit cell is made of 96 atoms. The ZIA phases extend the concept of\nnanolaminated crystalline solids well beyond the MAX phases family of early\ntransition metal carbides/nitrides, most likely broadening the spectrum of\nachievable material properties into domains typically not covered by the MAX\nphases. Furthermore, this work uncovers that both families of nanolaminated\ncrystalline solids, \\textit{i.e.}, the herein introduced \\textit{fcc} ZIA\nphases and all known variants of the \\textit{hcp} MAX phases, obey the same\noverarching stoichiometric rule $P_{x+y}A_xN_y$, where $x$ and $y$ are integers\nranging from 1 to 6.",
        "positive": "Achieving accurate ionization potential of semiconductors by the\n  efficient Kohn-Sham scheme of density functional theory: Despite of its huge successes in vast amount of applications, the Kohn-Sham\nscheme of density functional theory (DFT-Kohn-Sham) has not been able to get\nreliable ionization potentials (IP) for semiconductors, due to self-interaction\nerror in the local density approximation (LDA) and generalized gradient\napproximations (GGA), and the difficulty of using asymptotically long-ranged\npotentials for surface calculations. An approximate optimize effective\npotential (OEP), the Becke-Johnson'06 exchange, is used to explore the\ncapability of OEP to calculate semiconductor IP with a surface technique\nsuitable for both short- and long-ranged potentials. Combined with the LDA\ncorrelation, the approximate OEP has achieved an IP accuracy for 17\nsemiconductors which is similar to the much more sophisticated $GW$\napproximation (GWA), with the computational cost of only LDA/GGA. For the first\ntime, this opens the way for systematic calculation of semiconductor IP's by\nthe DFT-Kohn-Sham scheme. The long-range part of the $v_{xc}$ is not as\nimportant for solid surface as for atoms and molecules since the wave functions\nare mainly bound to the slab while less exposed to the asymptotic region.\nNevertheless, it contributes significantly to the total IP and therefore shall\nnot be simply ignored. Without including its effects, it is unlikely that the\nsame GWA procedure could achieve universally accurate band gaps and accurate\nIP's at the same time, as is indeed seen in practical calculations."
    },
    {
        "anchor": "\"Phase\" diagram of Izing and Heisenberg cubic clusters: We have studied the ground state of a simple cubic magnetic cluster, which\ncontains a spin s at each corner site. The ground state of such cluster depends\non the competition between nearest, next-nearest and next-next-nearest-neighbor\nexchange interactions. We have calculated the \"phase\" diagrams for the Izing\nclusters with s=1/2;1;3/2;5/2;\\infty and for the Heisenberg clusters with s=1/2\nand s=1. We have found that the \"phase\" diagram is remarkably independent on\nthe s value. It is important also that the Izing \"phase\" diagram can be used as\na rough approximation for the Heisenberg model.",
        "positive": "Magnetic and magnetoresistive properties of cubic Laves phase HoAl$_2$\n  single crystal: We report the magnetization ($M$) and magnetoresistance (MR) results of\nHoAl$_2$ single crystals oriented along $<100>$ and $<110>$ directions.\nAlthough HoAl$_2$ has cubic Laves phase structure, a large anisotropy is\nobserved in $M$ and MR results below Curie temperature ($T_C$) at 31.5 K. A\nsatisfactory correlation between magnetic entropy change ($\\Delta S_M$) and MR\ncould be established along $<110>$ direction and in $<100>$ direction except\nfor the temperature ($T$) region, around which spin reorientation takes place.\nLarge inverse magnetocaloric effect is observed at low-$T$ which is associated\nwith the spin reorientation process in $<100>$ direction. A theoretical model\nbased on Landau theory of phase transition can describe $T$-variation of\n-$\\Delta S_M$ for $T > T_C$."
    },
    {
        "anchor": "Liquid Epitaxial Growth of Two-dimensional Non-layer structured hybrid\n  Perovskite: The hybrid perovskite CH3NH3PbX3 (X= Cl, Br, I) is a promising material for\ndeveloping novel optoelectronic devices. Owing to the intrinsic non-layer\nstructure, it remains challenging to synthesize molecularly thin CH3NH3PbX3\nwith large size. Here, we report a low-cost and highly efficient fabrication\nroute to obtain large-scale single-crystalline 2D CH3NH3PbX3 perovskites on a\nmica substrate via liquid epitaxy. The 2D perovskite is characterized as 8 nm\nin thickness and hundreds of micrometers in lateral size. First-principles\ncalculations suggest the strong potassium-halogen interactions at the\nperovskite/mica interface lower the interface energy of perovskites, driving\ntheir fast in-plane growth. Spectroscopic investigations reveal 2D CH3NH3PbBr3\npossess small exciton binding energy of 30 meV, allowing a superior\nvisible-light photodetector with a photoresponsivity of 126 A/W and a bandwidth\nexceeded 80 kHz. These features demonstrate that liquid epitaxy is a bottom-up\napproach to fabricate the non-layer structured 2D perovskites, which offer a\nnew material platform for the device applications and fundamental\ninvestigations.",
        "positive": "Dynamical resonance quench and Fano interference in spontaneous Raman\n  scattering from quasiparticle and collective excitations: Time-resolved spontaneous Raman spectroscopy serves as a probe for incoherent\nquasiparticle and collective excitation dynamics, and allows to distinguish\nsymmetry changes across a photoinduced phase transition through the inelastic\nlight scattering selection rules. Largely unexplored is the role of the Raman\nresonance enhancement in the time-domain, and the transient interaction between\nscattering from quasiparticles and collective excitations, with the latter\ninteraction leading to a Fano interference.\n  In this work, we report on the observation of a phonon Raman tensor quench\nand Fano interference after strong photoexcitation of an intrinsic\nsemiconductor. We observed a dynamic phonon scattering rate asymmetry and\nspectral asymmetry through simultaneous detection of both the anti-Stokes and\nStokes response. The asymmetric phonon scattering rate is ascribed to the\ncombined effect of the transient phonon population and the reduction of the\nphonon Raman tensor resulting from the photoexcited hole population. This same\nhole population results in a strong enhancement of the Fano spectral asymmetry."
    },
    {
        "anchor": "Optical properties of yttrium oxyhydrides: A comparative analysis with\n  experiment: Based on the results of computational simulations, the research addresses a\nbroad range of electronic and optical properties which are typical for two most\nstable compositions of the yttrium oxyhydride, Y4H10O and YHO. Emphasis was\nplaced on characteristics of thin films of different structural phases.\nMacroscopic optical properties were deduced and analyzed within the\nconventional scheme that utilizes the knowledge of refractive index,\nabsorption, transmittance and reflectance spectra. Our major goal was two-fold:\nFirst, to provide modeling and description of optical spectra for various\nsingle- and bi-phase oxyhydride compositions, and second, to conduct\ncomparative analysis that would be powerful enough to explain the features of\nthe experimentally measured transmittance spectra. In the context of nonlinear\noptics, for the P-43m noncentrosymmetric cubic structure of Y4H10O we evaluated\na frequency profile of the second-order susceptibility ${\\chi}^{(2)}(2\\omega)$\nand showed that the bulk Y4H10O may exhibit a rather considerable optical\nnonlinearity.",
        "positive": "Black Phosphorus-Polymer Composites for Pulsed Lasers: Black phosphorus is a very promising material for telecommunication due to\nits direct bandgap and strong resonant absorption in near-infrared wavelength\nrange. However, ultrafast nonlinear photonic applications relying on the\nultrafast photo-carrier dynamics as well as optical nonlinearity in black\nphosphorus remain unexplored. In this work, we investigate nonlinear optical\nproperties of solution exfoliated BP and demonstrate the usage of BP as a new\nsaturable absorber for high energy pulse generation in fiber laser. In order to\navoid the oxidization and degradation of BP, we encapsulated BP by polymer\nmatrix which is optically transparent in the spectrum range of interest to form\na composite. Two fabrication approaches were demonstrated to produce BP-polymer\ncomposite films which were further incorporated into fiber laser cavity as\nnonlinear media. BP shows very fast carrier dynamics and BP-polymer composite\nhas a modulation depth of 10.6%. A highly stable Q-switched pulse generation\nwas achieved and the single pulse energy of ~194 nJ was demonstrated. The ease\nof handling of such black phosphorus-polymer composite thin films affords new\nopportunities for wider applications such as optical sensing, signal processing\nand light modulation."
    },
    {
        "anchor": "Frequency-resolved microscopic current density analysis of linear and\n  nonlinear optical phenomena in solids: We perform a frequency-resolved analysis of electron dynamics in solids to\nobtain microscopic insight into linear and nonlinear optical phenomena. For the\nanalysis, we first compute the electron dynamics under optical electric fields\nand evaluate the microscopic current density as a function of time and space.\nSubsequently, we perform the Fourier transformation on the microscopic current\ndensity and obtain the corresponding quantity in the frequency domain. The\nfrequency-resolved microscopic current density provides insight into the\nmicroscopic electron dynamics in real-space at the frequency of linear and\nnonlinear optical responses. We apply frequency-resolved microscopic current\ndensity analysis to light-induced electron dynamics in aluminum, silicon, and\ndiamond based on the first-principles electron dynamics simulation according to\nthe time-dependent density functional theory. Consequently, the nature of\ndelocalized electrons in metals and bound electrons in semiconductors and\ninsulators is suitably captured by the developed scheme.",
        "positive": "Inverse design for Casimir-Lifshitz force near heterogeneous gapped\n  metal surface: The Casimir-Lifshitz force is calculated between a heterogeneous gapped metal\nsurface and a silica sphere attached to an AFM cantilever tip. We demonstrate\nthat heterogeneous surface patches with different off-stoichiometry surface\nproperties lead to changes in the predicted distances for a specific force.\nThis can incorrectly be interpreted as occurrences of surface roughness."
    },
    {
        "anchor": "Structural properties of Silicon-Germanium and Germanium-Silicon\n  Core-Shell Nanowires: Core-shell nanowires made of Si and Ge can be grown experimentally with\nexcellent control for different sizes of both core and shell. We have studied\nthe structural properties of Si/Ge and Ge/Si core-shell nanowires aligned along\nthe $[110]$ direction, with diameters up to 10.2~nm and varying core to shell\nratios, using linear scaling Density Functional Theory (DFT). We show that\nVegard's law, which is often used to predict the axial lattice constant, can\nlead to an error of up to 1\\%, underlining the need for a detailed \\emph{ab\ninitio} atomistic treatment of the nanowire structure. We analyse the character\nof the intrinsic strain distribution and show that, regardless of the\ncomposition or bond direction, the Si core or shell always expands. In\ncontrast, the strain patterns in the Ge shell or core are highly sensitive to\nthe location, composition and bond direction. The highest strains are found at\nheterojunction interfaces and the surfaces of the nanowires. This detailed\nunderstanding of the atomistic structure and strain paves the way for studies\nof the electronic properties of core-shell nanowires and investigations of\ndoping and structure defects.",
        "positive": "Soft phonon columns on the edge of the Brillouin zone in the relaxor\n  PbMg1/3Nb2/3O3: We report lattice dynamical measurements, made using neutron inelastic\nscattering methods, of the relaxor perovskite PbMg1/3Nb2/3O3 (PMN) at momentum\ntransfers near the edge of the Brillouin zone. Unusual\"columns\" of phonon\nscattering that are localized in momentum, but extended in energy, are seen at\nboth high-symmetry points along the zone edge: \\vec{Q}_R={1/2, 1/2, 1/2} and\n\\vec{Q}_M={1/2,1/2,0}. These columns soften at ~400 K which is similar to the\nonset temperature of the zone-center diffuse scattering, indicating a\ncompetition between ferroelectric and antiferroelectric distortions. We propose\na model for the atomic displacements associated with these phonon modes that is\nbased on a combination of structure factors and group theoretical analysis.\nThis analysis suggests that the scattering is not from tilt modes (rotational\nmodes of oxygen octahedra), but from zone-boundary optic modes that are\nassociated with the displacement of Pb^{2+} and O^{2-} ions. Whereas similar\ncolumns of scattering have been reported in metallic and (less commonly)\nmolecular systems, they are unusual in insulating materials, particularly in\nferroelectrics; therefore, the physical origin of this inelastic feature in PMN\nis unknown. We speculate that the underlying disorder contributes to this\nunique anomaly."
    },
    {
        "anchor": "First-principles study of cubic perovskites SrMO_3 (M = Ti, V, Zr and\n  Nb): Using the full-potential linearized-augmented-plane-wave (FLAPW) method, we\nhave analyzed systematically the trends in the structural and electronic\nproperties of the 3d and 4d transition-metal oxides SrMO_3 (M = Ti, V, Zr and\nNb). The optimized lattice parameters, bulk modules, densities of states, band\nstructures and charge density distributions are obtained and compared with the\navailable theoretical and experimental data. The energy gap between O2p - Md\nbands increases as the covalency of the system decreases going from 3d to 4d\nbased perovskites. The electron configurations of Sr(Ti,Zr)O_3 and Sr(V,Nb)O_3\nusually referred to as d^0 and d^1 oxides, respectively, differ considerably\nfrom these idealized \"ionic\" configurations, and the deviations increase with\nincreasing of the d-p covalent overlap in the oxides.",
        "positive": "Density-of-states similarity descriptor for unsupervised learning from\n  materials data: We develop a materials descriptor based on the electronic density of states\nand investigate the similarity of materials based on it. As an application\nexample, we study the Computational 2D Materials Database that hosts thousands\nof two-dimensional materials with their properties calculated by\ndensity-functional theory. Combining our descriptor with a clustering\nalgorithm, we identify groups of materials with similar electronic structure.\nWe characterize these clusters in terms of their crystal structure, their\natomic composition, and the respective electronic configurations to rationalize\nthe found (dis)similarities."
    },
    {
        "anchor": "Impurity bands and the character of the electronic states in\n  ferromagnetic GaMnAs layers: The interplay between disorder and spin polarization in a GaMnAs thin layer\nresults into spin-polarized impurity hole bands. A figure of merit is defined\nto label the hole state as being extended or localized. The calculation leads\nto a phase diagram determining the metallic or non-metallic character of the\nsample. It is shown that samples with the highest figures of merit have a ratio\nbetween the extended hole density and the Mn concentration near 0.2, in\nagreement with the ratio of 0.1-0.25 known to occur among samples produced with\nthe highest Curie temperatures. Both the non-metal-to-metal and the\nmetal-to-non-metal transitions experimentally observed in the ferromagnetic\nregime are obtained, as the Mn concentration increases. An explanation is given\nfor the occurrence of a maximal Curie temperature in ferromagnetic GaMnAs\nsamples.",
        "positive": "Nonradiative DKR processes: revisiting the theory. IV. On the\n  controversy over a polaron state bound to an F center in alkali halides: We are commenting on an earlier hypothesis of polaron states bound to F\ncenters in alkali halides. These states increasing the effective size of the\ncolor centers, they play an active role in concentration-dependent phenomena,\nsuch as the observed quenching of F center luminescence. Our record shows only\none related study on NaBr and NaI which has also been aimed at checking the\nbound polaron hypothesis. Further studies of the concentration quenching in\nother alkali halide hosts whould eventually shine more light on the problem."
    },
    {
        "anchor": "Edge and Width Dependent Electronic Properties of Nanoribbons of\n  Manganese Oxide: In the present work, the structural, magnetic, and electronic properties of\nthe two- and one-dimensional honeycomb structures of recently synthesized MnO\n[Zhang et al. Nat. Commun., 20, 1073-1078 (2021)] are investigated by using\nfirst principles calculations. Our calculations show that the single layer 2D\nMnO crystal has a degenerate antiferromagnetic (AFM) ground state and a\nrelatively less favorable ferromagnetic (FM) state. In addition, magnetic\nanisotropy calculations unveil that the easy-axis direction for magnetism\noriginating from unpaired electron states in manganese atoms is normal to the\ncrystal plane. Electronically, while the FM-MnO is a direct semiconductor with\na narrow bandgap, AFM phases display large indirect bandgap semiconducting\nbehavior. Moreover, calculations on nanoribbons of MnO reveal that zigzag edged\nribbons display metallic bahavior, whereas armchair edged nanoribbons are\nsemiconductors. Magnetically, for both zigzag- or armchair-edged nanoribbons,\nAFM order perpendicular to the nanoribbon growth direction is found to be\nfavorable over the other AFM and FM orders. Moreover, depending on the edge\nsymmetry and ribbon width, forbidden band gap values of nanoribbons display\ndistinct family behaviors.",
        "positive": "Barrier efficiency of sponge-like La2Zr2O7 buffer layers for YBCO-coated\n  conductors: Solution derived La2Zr2O7 films have drawn much attention for potential\napplications as thermal barriers or low-cost buffer layers for coated conductor\ntechnology. Annealing and coating parameters strongly affect the microstructure\nof La2Zr2O7, but different film processing methods can yield similar\nmicrostructural features such as nanovoids and nanometer-sized La2Zr2O7 grains.\nNanoporosity is a typical feature found in such films and the implications for\nthe functionality of the films is investigated by a combination of scanning\ntransmission electron microscopy, electron energy-loss spectroscopy and\nquantitative electron tomography. Chemical solution based La2Zr2O7 films\ndeposited on flexible Ni-5at.%W substrates with a {100}<001> biaxial texture\nwere prepared for an in-depth characterization. A sponge-like structure\ncomposed of nanometer sized voids is revealed by high-angle annular dark-field\nscanning transmission electron microscopy in combination with electron\ntomography. A three-dimensional quantification of nanovoids in the La2Zr2O7\nfilm is obtained on a local scale. Mostly non-interconnected highly facetted\nnanovoids compromise more than one-fifth of the investigated sample volume. The\ndiffusion barrier efficiency of a 170 nm thick La2Zr2O7 film is investigated by\nSTEM-EELS yielding a 1.8 \\pm 0.2 nm oxide layer beyond which no significant\nnickel diffusion can be detected and intermixing is observed. This is of\nparticular significance for the functionality of YBa2Cu3O7-{\\delta} coated\nconductor architectures based on solution derived La2Zr2O7 films as diffusion\nbarriers."
    },
    {
        "anchor": "Quantal Density Functional Theory of Degenerate States: The treatment of degenerate states within Kohn-Sham density functional theory\n(KS-DFT) is a problem of longstanding interest. We propose a solution to this\nmapping from the interacting degenerate system to that of the noninteracting\nfermion model whereby the equivalent density and energy are obtained via the\nunifying physical framework of quantal density functional theory (Q-DFT). We\ndescribe the Q-DFT of \\textit{both} ground and excited degenerate states, and\nfor the cases of \\textit{both} pure state and ensemble v-representable\ndensities. This then further provides a rigorous physical interpretation of the\ndensity and bidensity energy functionals, and of their functional derivatives,\nof the corresponding KS-DFT. We conclude with examples of the mappings within\nQ-DFT.",
        "positive": "Experimental verification of polar structures in ultrathin BaTiO_{3}\n  layers using resonant x-ray reflectivity: Functional devices with ultrathin ferroelectric layers have been attracted as\na promising candidate for next-generation memory and logic device applications.\nUsing the ultrathin ferroelectric layers, particularly approaching the\ntwo-dimensional limit, however, it is still challenging to control\nferroelectric switching and to observe ferroelectricity by spectroscopic tools.\nIn particular, conventional methods such as electrical measurements and\npiezoelectric response force microscopy are very limited due to leakage\ncurrents and the smallness of the ferroelectric signals. Here, we show that the\nferroelectricity of ultrathin SrRuO3/BaTiO3/SrRuO3 heterostructures grown on\nSrTiO3(100) substrates can be measured using resonant x-ray reflectivity\n(RXRR). This experimental technique can provide an element-specific electronic\ndepth profile as well as increased sensitivity to Ti off-center displacements\nat the Ti K pre-edge. The depth-sensitivity of RXRR selectively detects the\nstrong polarization dependence of the Ti pre-edge features of ultrathin BaTiO3\nlayers while discriminating the contribution of the SrTiO3 substrate. This\ntechnique verified that the BaTiO3 layer can be ferroelectric down to the\nlowest experimental limit of a critical thickness of 2.5 unit cells. Our\nresults can open a novel way to explore ultrathin ferroelectric-based\nnano-electronic devices."
    },
    {
        "anchor": "Nearest neighbor exchange in Co- and Mn-doped ZnO: We calculate the magnetic interactions between two nearest neighbor\nsubstitutional magnetic ions (Co or Mn) in ZnO by means of density functional\ntheory and compare it with the available experimental data. Using the local\nspin density approximation we find a coexistence of ferro- and\nantiferromagnetic couplings for ZnO:Co, in contrast to experiment. For ZnO:Mn\nboth couplings are antiferromagnetic but deviate quantitatively from\nmeasurement. That points to the necessity to account better for the strong\nelectron correlation at the transition ion site which we have done by applying\nthe LSDA+U method. We show that we have to distinguish two different nearest\nneighbor exchange integrals for the two systems in question which are all\nantiferromagnetic with values between -1.0 and -2.0 meV in reasonable agreement\nwith experiment.",
        "positive": "Structural and Magnetic Properties of Pyrochlore Solid Solutions\n  (Y,Lu)2Ti2-x(Nb,Ta)xO7+/-y: The synthesis and characterization of the pyrochlore solid solutions,\nY2Ti2-xNbxO7-y, Lu2Ti2-xNbxO7-y, Y2Ti2-xTaxO7-y and Lu2TiTaO7-y (-0.4<y<0.5),\nis described. Synthesis at 1600 C, and 10-5 Torr yields oxygen deficiency in\nall systems. All compounds are found to be paramagnetic and semiconducting,\nwith the size of the local moments being less, in some cases substantially\nless, than the expected value for the number of nominally unpaired electrons\npresent. Thermogravimetric analysis (TGA) shows that all compounds can be fully\noxidized while retaining the pyrochlore structure, yielding oxygen rich\npyrochlores as white powders. Powder neutron diffraction of Y2TiNbO7-based\nsamples was done. Refinement of the data for oxygen deficient Y2TiNbO6.76\nindicates the presence of a distribution of oxygen over the 8b and 48f sites.\nRefinement of the data for oxygen rich Y2TiNbO7.5 shows these sites to be\ncompletely filled, with an additional half filling of the 8a site. The magnetic\nand TGA data strongly suggest a preference for a Ti3+/(Nb,Ta)5+ combination, as\nopposed to Ti4+/(Nb,Ta)4+, in this pyrochlore family. In addition, the evidence\nclearly points to Ti3+ as the source of the localized moments, with no evidence\nfor localized Nb4+ moments."
    },
    {
        "anchor": "Exchange-driven spin Hall effect in anisotropic ferromagnets: Crystallographic anisotropy of the spin-dependent conductivity tensor can be\nexploited to generate transverse spin-polarized current in a ferromagnetic\nfilm. This ferromagnetic spin Hall effect is analogous to the spin-splitting\neffect in altermagnets and does not require spin-orbit coupling.\nFirst-principles screening of 41 non-cubic ferromagnets revealed that many of\nthem, when grown as a single crystal with tilted crystallographic axes, can\nexhibit large spin Hall angles comparable with the best available\nspin-orbit-driven spin Hall sources. Macroscopic spin Hall effect is possible\nfor uniformly magnetized ferromagnetic films grown on some low-symmetry\nsubstrates with epitaxial relations that prevent cancellation of contributions\nfrom different orientation domains. Macroscopic response is also possible for\nany substrate if magnetocrystalline anisotropy is strong enough to lock the\nmagnetization to the crystallographic axes in different orientation domains.",
        "positive": "Energy exchanges between atoms with a quartz crystal $\u03bc$-balance: We propose an experimental method to fully characterize the energy exchange\nof particles during the physical vapor deposition process of thin surface\nlayers. Our approach is based on the careful observation of perturbations of\nthe oscillation frequency of a Quartz Crystal $\\mu$-balance induced by the\nparticles interaction. With this technique, it is possible to measure the\nmomentum exchange of the atoms during the evaporation process and determine the\nideal evaporation rate for an uniform energy distribution. We are able to\nfollow the desorption dynamics of particles immediately after the first layers\nhave been formed. These results are in close relation to the surface binding\nenergy of the evaporated material, they offer a better control to obtain the\ndesired properties of the thin surface layer. We applied our technique to\ninvestigate the physical vapor evaporation process for diverse elements,\nusually implemented in the development of film surface layers, such as Cu, W,\nAu, Gd and In, and confirm that our results are in agreement with measurements\ndone previously with other techniques such as low-temperature\nphotoluminescence."
    },
    {
        "anchor": "Arbitrary Choice of Basic Variables in Density Functional Theory. II.\n  Illustrative Applications: Our recent theory (Ref. 1) enables us to choose arbitrary quantities as the\nbasic variables of the density functional theory. In this paper we apply it to\nseveral cases. In the case where the occupation matrix of localized orbitals is\nchosen as a basic variable, we can obtain the single-particle equation which is\nequivalent to that of the LDA+U method. The theory also leads to the\nHartree-Fock-Kohn-Sham equation by letting the exchange energy be a basic\nvariable. Furthermore, if the quantity associated with the density of states\nnear the Fermi level is chosen as a basic variable, the resulting\nsingle-particle equation includes the additional potential which could mainly\nmodify the energy-band structures near the Fermi level.",
        "positive": "Thermodynamic Analysis of Titanium Removal from Molten iron Smelted with\n  Large Amounts of Sodium Additives: High purity iron is obtained from vanadium-titanium magnetite (VTM) by\none-step coal-based direct reduction-smelting process with coal as reductant\nand sodium carbonate (Na2CO3) as additives. Industrial experiments show that\nthe process of treating molten iron with a large amount of Na2CO3 is effective\nin removing titanium from molten iron. However, the studies are rarely\nconducted in thermodynamic relationship between titanium and other components\nof molten iron, under the condition of a large amount of Na2CO3 additives. In\nthis study, through the thermodynamic database software Factsage8.0, the\neffects of melting temperature, sodium content and oxygen content on the\nremoval of titanium from molten iron are studied. The results of thermodynamic\ncalculation show that the removal of titanium from molten iron needs to be\nunder the condition of oxidation, and the temperature should be below the\ncritical temperature of titanium removal (the highest temperature at which\ntitanium can be removed). Relatively low temperature and high oxygen content\ncontribute to the removal of titanium from molten iron. The high oxygen content\nis conducive to the simultaneous removal of titanium and phosphorus from molten\niron. In addition, from a thermodynamic point of view, excessive sodium\naddition inhibits the removal of titanium from molten iron."
    },
    {
        "anchor": "Tuning the metamagnetic transition in the (Co,Fe)MnP system for\n  magnetocaloric purposes: The inverse magnetocaloric effect taking place at the\nantiferro-to-ferromagnetic transition of (Co,Fe)MnP phosphides has been\ncharacterized by magnetic and direct {\\Delta}Tad measurements. In\nCo0.53Fe0.47MnP, entropy change of 1.5 Jkg-1K-1 and adiabatic temperature\nchange of 0.6 K are found at room temperature for an intermediate field change\n({\\Delta}B= 1 T). Several methods were used to control the metamagnetic\ntransition properties, in each case a peculiar splitting of the\nantiferro-to-ferromagnetic transition is observed.",
        "positive": "High-temperature structural phase transition and infrared dielectric\n  features of La2CoMnO6: Temperature-dependent FAR-infrared reflectivity spectra of partially ordered\nmagnetodielectric La2CoMnO6 is presented, from room temperature up to 675 K. A\nclear first-ordered structural phase transition (SPT) from a monoclinic\nstructure with P2_1/n symmetry to a rhombohedral phase with R-3 symmetry was\nevidenced from the behaviour of polar phonon modes at TC~590 K. The temperature\ndependences of the transversal and longitudinal phonon branches, dielectric\nstrengths, and damping of the strongest dielectric modes confirm the\nsignificant contribution of the phonon modes on the SPT, and revealed an\nimportant lattice anharmonicity, particularly for the low frequency modes. In\naddition, these investigations showed that structural ordering does not inhibit\nthe SPT, and provided valuable information towards the polar phonons, their\nimplications on intrinsic dielectric constant in double perovskites and in\nrelated compounds."
    },
    {
        "anchor": "Epitaxial Growth of Large-area Bilayer Graphene on Ru(0001): Large-area bilayer graphene (BG) is grown epitaxially on Ru(0001) surface and\ncharacterized by low temperature scanning tunneling microscopy. The lattice of\nthe bottom layer of BG is stretched by 1.2%, while strain is absent from the\ntop layer. The lattice mismatch between the two layers leads to the formation\nof a moire pattern with a periodicity of ~21.5 nm and a mixture of AA- and\nAB-stacking. The root3 x root3 superstructure around atomic defects is\nattributed to the inter-valley scattering of the delocalized pi-electrons,\ndemonstrating that the as-grown BG behaves like intrinsic free-standing\ngraphene.",
        "positive": "First-principles calculations of defects in metal halide perovskites: a\n  performance comparison of density functionals: Metal halide perovskite semiconductors have outstanding optoelectronic\nproperties. Although these perovskites are defect-tolerant electronically,\ndefects hamper their long-term stability and cause degradation. Density\nfunctional theory (DFT) calculations are an important tool to unravel the\nmicroscopic structures of defects, but results suffer from the different\napproximations used in the DFT functionals. In the case of metal halide\nperovskites, qualitatively different results have been reported with different\nfunctionals, either predicting vacancy or interstitial point defects to be most\ndominant. Here, we conduct a comprehensive comparison of a wide range of\nfunctionals for calculating the equilibrium defect formation energies and\nconcentrations of point defects in the archetype metal halide perovskite,\nMAPbI$_3$. We find that it is essential to include long-range Van der Waals\ninteractions in the functional, and that it is vital to self-consistently\noptimize structure and volume of all compounds involved in the defect\nformation. For calculating equilibrium formation energies of point defects in\nMAPbI$_3$ and similar metal halide perovskites, we argue that the exact values\nof the chemical potentials of the species involved, or of the intrinsic Fermi\nlevel, are not important. In contrast to the simple Schottky or Frenkel\npictures, we find that the dominant defects are MA and I interstitials, and Pb\nvacancies."
    },
    {
        "anchor": "Hydrogen solubility in zirconium intermetallic second phase particles: The enthalpies of solution of H in Zr binary intermetallic compounds formed\nwith Cu, Cr, Fe, Mo, Ni, Nb, Sn and V were calculated by means of density\nfunctional theory simulations and compared to that of H in {\\alpha}-Zr. It is\npredicted that all Zr-rich phases (formed with Cu, Fe, Ni and Sn), and those\nphases formed with Nb and V, offer lower energy, more stable sites for H than\n{\\alpha}-Zr. Conversely, Mo and Cr containing phases do not provide\npreferential solution sites for H. In all cases the most stable site for H are\nthose that offer the highest coordination fraction of Zr atoms. Often these are\nfour Zr tetrahedra but not always. Implications with respect to H-trapping\nproperties of commonly observed ternary phases such as Zr(Cr,Fe)2, Zr2(Fe,Ni)\nand Zr(Nb,Fe)2 are also discussed.",
        "positive": "Ultrafast and widely tuneable vertical-external-cavity surface-emitting\n  laser, mode-locked by a graphene-integrated distributed Bragg reflector: We report a versatile and cost-effective way of controlling the unsaturated\nloss, modulation depth and saturation fluence of graphene-based saturable\nabsorbers (GSAs), by changing the thickness of a spacer between SLG and a\nhigh-reflection mirror. This allows us to modulate the electric field intensity\nenhancement at the GSA from 0 up to 400%, due to the interference of incident\nand reflected light at the mirror. The unsaturated loss of the\nSLG-mirror-assembly can be reduced to$\\sim$0. We use this to mode-lock a VECSEL\nfrom 935 to 981nm. This approach can be applied to integrate SLG into various\noptical components, such as output coupler mirrors, dispersive mirrors,\ndielectric coatings on gain materials. Conversely, it can also be used to\nincrease absorption (up to 10%) in various graphene based photonics and\noptoelectronics devices, such as photodetectors."
    },
    {
        "anchor": "Spectroscopic Signatures of Photogenerated Radical Anions in\n  Polymer-[C70]Fullerene Bulk Heterojunctions: Light induced polarons in solid films of polymer-fullerene blends were\nstudied by applying photoluminescence (PL), photo induced absorption (PIA)\ntechniques as well as electron spin resonance (ESR). The materials used were\npoly(3-hexylthiophene) (P3HT) and poly-[2-methoxy, 5-(2'-ethyl-hexyloxy)\nphenylene vinylene] (MEH-PPV) as donors. As acceptors we used\n[6,6]-phenyl-C61-butyric acid methyl ester ([C60]PCBM) and various soluble\nC70-derivates: [C70]PCBM, diphenylmethano[70]fullerene oligoether (C70-DPM-OE),\nC70-DPM-OE2, and two fullerene dimers, C70-C70 and C60-C70 (all shown in figure\n1). In all blends containing C70 we found typical signatures which were absent\nif [C60]PCBM was used as acceptor. Light-induced ESR revealed signals at\ng>=2.005, which we previously assigned to an electron localized on the C70\ncage, the PIA measurements showed a new sub-bandgap absorption band at 0.92 eV,\nwhich we correspondingly ascribe to C70 radical anions formed in the course of\nphotoinduced electron transfer from donor to acceptor.",
        "positive": "Bulk Band Structure of Bi$_2$Te$_3$: The bulk band structure of Bi$_2$Te$_3$ has been determined by angle-resolved\nphotoemission spectroscopy and compared to first-principles calculations. We\nhave performed calculations using the local density approximation (LDA) of\ndensity functional theory and the one-shot $GW$ approximation within the\nall-electron full-potential linearized augmented-plane-wave (FLAPW) formalism,\nfully taking into account spin-orbit coupling. Quasiparticle effects produce\nsignificant changes in the band structure of \\bite~when compared to LDA.\nExperimental and calculated results are compared in the spectral regions where\ndistinct differences between the LDA and $GW$ results are present. Overall a\nsuperior agreement with $GW$ is found, highlighting the importance of many-body\neffects in the band structure of this family of topological insulators."
    },
    {
        "anchor": "Growth in multi-component alloys: Theoretical and numerical\n  determination of phase concentrations: Understanding the role of solute diffusivities in equilibrium tie-line\nselection during growth of a second phase in ternary and higher multicomponent\ntwo phase alloys is an important problem due to the strong dependence of\nmechanical properties on compositions. In this paper, we derive analytical\nexpressions for predicting tie-lines and composition profiles in the matrix\nduring growth of planar and cylindrical precipitates with the assumption of\ndiagonal diffusivity matrices. We confirm our calculations by sharp interface\nand phase field simulations. The numerical techniques are in turn utilized for\ninvestigating the role of off-diagonal entries in the diffusivity matrix. In\naddition, the sharp interface methods allow for the tracking of the tie-line\ncompositions during growth of 2D precipitates which contribute to an\nunderstanding of the change in equilibrium tie-lines chosen by the system\nduring growth.",
        "positive": "Spectroscopic imaging ellipsometry of two-dimensional TMDC\n  heterostructures: Semiconducting two-dimensional materials and their heterostructures gained a\nlot of interest for applications as well as fundamental studies due to their\nrich optical properties. Assembly in van der Waals heterostacks can\nsignificantly alter the intrinsic optical properties as well as the\nwavelength-dependent absorption and emission efficiencies making a direct\ncomparison of e.g. photoluminescence intensities difficult. Here, we determine\nthe dielectric function for the prototypical MoSe2/WSe2 heterobilayer and their\nindividual layers. Apart from a redshift of 18 meV - 44 meV of the\nenergetically lowest interband transitions, we find that for larger energies\nthe dielectric function can only be described by treating the van der Waals\nheterobilayer as a new artificial homobilayer crystal rather than a stack of\nindividual layers. The determined dielectric functions are applied to calculate\nthe Michelson contrast of the individual layers and the bilayer in dependence\nof the oxide thickness of often used Si/SiO2 substrates. Our results highlight\nthe need to consider the altered dielectric functions impacting the Michelson\ninterference in the interpretation of intensities in optical measurements such\nas Raman scattering or photoluminescence."
    },
    {
        "anchor": "Coexistence of surface and bulk state and negative magnetoresistance in\n  Sulfur doped Bi2Se3: The magneto-transport properties in Sulfur doped Bi2Se3 are investigated. The\nmagnetoresistance (MR) decreases with increase of S content and finally for 7%\n(i.e. y=0.21) S doping the magnetoresistance becomes negative. This negative MR\nis unusual as it is observed when magnetic field is applied with the\nperpendicular direction to the plane of the sample. The magneto-transport\nbehavior shows the shubnikov-de hass (SdH) oscillation indicating the\ncoexistence of both surface and bulk states. The negative MR has been\nattributed to the bulk conduction.",
        "positive": "Detecting Atomic Scale Surface Defects in STM of TMDs with Ensemble Deep\n  Learning: Atomic-scale defect detection is shown in scanning tunneling microscopy\nimages of single crystal WSe2 using an ensemble of U-Net-like convolutional\nneural networks. Standard deep learning test metrics indicated good detection\nperformance with an average F1 score of 0.66 and demonstrated ensemble\ngeneralization to C-AFM images of WSe2 and STM images of MoSe2. Defect\ncoordinates were automatically extracted from defect detections maps showing\nthat STM image analysis enhanced by machine learning can be used to\ndramatically increase sample characterization throughput."
    },
    {
        "anchor": "Density functional theory study of phase IV of solid hydrogen: We have studied solid hydrogen up to pressures of 300 GPa and temperatures of\n350 K using density functional theory methods and have found \"mixed structures\"\nthat are more stable than those predicted earlier. Mixed structures consist of\nalternate layers of strongly bonded molecules and weakly bonded graphene-like\nsheets. Quasi-harmonic vibrational calculations show that mixed structures are\nthe most stable at room temperature over the pressure range 250-295 GPa. These\nstructures are stabilized with respect to strongly-bonded molecular phases at\nroom temperature by the presence of lower-frequency vibrational modes arising\nfrom the graphene-like sheets. Our results for the mixed structures are\nconsistent with the experimental Raman data [M. I. Eremets and I. A. Troyan,\nNature Mater. 10 927 (2011) and R. T. Howie et al. Phys. Rev. Lett. 108 125501\n(2012)]. We find that mixed phases are reasonable structural models for phase\nIV of hydrogen.",
        "positive": "Magnetic critical behavior and anomalous Hall effect in\n  2H-Co$_{0.22}$TaS$_{2}$ single crystals: We report ferromagnetism in 2H-Co$_{0.22}$TaS$_2$ single crystals where Co\natoms are intercalated in the van der Waals gap, and a systematic study of its\nmagnetic critical behavior in the vicinity of $T_c \\sim 28$ K. The obtained\ncritical exponents $\\beta$ = 0.43(2), $\\gamma$ = 1.15(1), and $\\delta =\n3.54(1)$ fulfill the Widom scaling relation $\\delta = 1+\\gamma/\\beta$ and\nfollow the scaling equation. This indicates that the spin coupling in\n2H-Co$_{0.22}$TaS$_2$ is of three-dimensional Hersenberg type coupled with\nlong-range magnetic interaction, and that the exchange interaction decays with\ndistance as $J(r)\\approx r^{-4.69}$. 2H-Co$_{0.22}$TaS$_2$ exhibits a weak\ntemperature-dependent metallic behavior in resistivity and negative values of\nthermopower with dominant electron-type carriers, in which obvious anomalies\nwere observed below $T_c$ as well as the anomalous Hall effect (AHE). The\nlinear scaling behavior between the modified anomalous Hall resistivity\n$\\rho_{xy}/\\mu_0H$ and longitudinal resistivity $\\rho_{xx}^2M/\\mu_0H$ implies\nthat the origin of AHE in 2H-Co$_{0.22}$TaS$_2$ should be dominated by the\nextrinsic side-jump mechanism."
    },
    {
        "anchor": "Evolution of high-frequency Raman modes and their doping dependence in\n  twisted bilayer MoS2: Twisted van der Waals heterostructures unravel a new platform to study\nstrongly correlated quantum phases. The interlayer coupling in these\nheterostructures is sensitive to twist angles ($\\theta$) and key to\ncontrollably tune several exotic properties. Here, we demonstrate a systematic\nevolution of the interlayer coupling strength with twist angle in bilayer\n$\\mathrm{MoS_{2}}$ using a combination of Raman spectroscopy and classical\nsimulations. At zero doping, we show a \\textit{monotonic} increment of the\nseparation between the $\\mathrm{A_{1g}}$ and $\\mathrm{E^{1}_{2g}}$ mode\nfrequencies as $\\theta$ decreases from $10^{\\circ} \\to 1^{\\circ}$, which\nsaturates to that for a bilayer at small twist angles. Furthermore, using\ndoping-dependent Raman spectroscopy we reveal $\\theta$ dependent softening and\nbroadening of the $\\mathrm{A_{1g}}$ mode, whereas the $\\mathrm{E^{1}_{2g}}$\nmode remains unaffected. Using first principles-based simulations we\ndemonstrate large (weak) electron-phonon coupling for the $\\mathrm{A_{1g}}$\n($\\mathrm{E^{1}_{2g}}$) mode explaining the experimentally observed trends. Our\nstudy provides a non-destructive way to characterize the twist angle, the\ninterlayer coupling and establishes the manipulation of phonons in twisted\nbilayer $\\mathrm{MoS_{2}}$ (twistnonics).",
        "positive": "First evidence of transient interactions between $\u03c0\\to\u03c0^*$ optical\n  excitations and image potential states in graphite: Here we report the experimental evidence of the interactions between the\nexcitations of the $\\pi\\to\\pi^*$ optical transition and the image potential\nstates (IPS) of highly oriented pyrolitic graphite (HOPG). By using non-linear\nangle resolved photoelectron spectroscopy (NL-ARPES) we show that the IPS\nphotoemission intensity, the effective mass, and the linewidth exhibit a strong\nvariation when the photon energy is tuned across the $\\pi\\to\\pi^*$ saddle\npoints in the 3.1 - 4.5 eV photon energy range. A model based on the\nself-energy formalism is proposed to correlate the effective mass and the\nlinewidth variations to transient many body effects, when a high carriers\ndensity (in the $10^{20}$ cm$^{-3}$ range) is created by the absorption of a\ncoherent light pulse. This finding brings a clear evidence of a high IPS-bulk\ncoupling in graphite and opens the way for exploiting the IPS as a sensitive,\nnonperturbing probe for the many-body dynamics in materials."
    },
    {
        "anchor": "May silicene exist?: The letter presents arguments, supported by quantum-chemical calculations,\nagainst silicene to be produced",
        "positive": "Gas phase condensation of few-layer graphene with rotational stacking\n  faults in an electric-arc: We report the synthesis efficiency of few-layer graphene (FLG) in an external\nmagnetic field modulated DC carbon arc in different non-reactive buffer gases.\nThe effects of buffer gases on the anode erosion rate and the cathode deposit\n(CD) formation rate have been investigated during the synthesis of FLG. The\nconstituents of the as-synthesized CDs were investigated using transmission\nelectron microscopy, selected area electron diffraction, Raman spectroscopy and\nX-ray diffraction analysis. A plausible growth mechanism of such FLG is\npredicted. The results indicate that, under a parametrically optimized\ncondition, an electric-arc of this kind can efficiently generate FLG with\nrotational stacking faults at a production-rate of few g/min. A guideline for\ncontrolling the number of layers of such FLG has also been suggested."
    },
    {
        "anchor": "A Photoinduced Floquet Mixed-Weyl Semimetallic Phase in a Carbon\n  Allotrope: The interplay between light and matter attracts tremendous interest for\nexploring novel topological quantum states and their phase transitions. Here we\nshow by first-principles calculations and the Floquet theorem that a carbon\nallotrope bct-C$_{16}$, a typical nodal-line semimetal, exhibits exotic\nphotoinduced Floquet mixed-Weyl semimetallic features. Under the irradiation of\na linearly polarized light, bct-C$_{16}$ undergos a topological phase\ntransition from a Driac nodal-line semimetal to a Weyl semimetal with two pairs\nof tunable Weyl points. With increasing the light intensity, left-handed Weyl\npoints evolve from type-I into type-II while right-handed ones are always\npreserved to be type-I, giving rise to photo-dressed unconventional Weyl pairs\ncomposed of distinct types of Weyl points. Importantly, a special Weyl pair\nformed by type-I and type-III Weyl points is present at the boundary between\ntype-I and type-II states. The Floquet Fermi arcs connecting the projections of\ntwo different types of Weyl points are clearly visible, further revealing their\nunique topological features. Our work not only realizes promising\nunconventional Weyl pairs but also paves a reliable avenue for investigating\nlight-induced topological phase transitions.",
        "positive": "Reconstructing microstructures from statistical descriptors using neural\n  cellular automata: The problem of generating microstructures of complex materials in silico has\nbeen approached from various directions including simulation, Markov, deep\nlearning and descriptor-based approaches. This work presents a hybrid method\nthat is inspired by all four categories and has interesting scalability\nproperties. A neural cellular automaton is trained to evolve microstructures\nbased on local information. Unlike most machine learning-based approaches, it\ndoes not directly require a data set of reference micrographs, but is trained\nfrom statistical microstructure descriptors that can stem from a single\nreference. This means that the training cost scales only with the complexity of\nthe structure and associated descriptors. Since the size of the reconstructed\nstructures can be set during inference, even extremely large structures can be\nefficiently generated. Similarly, the method is very efficient if many\nstructures are to be reconstructed from the same descriptor for statistical\nevaluations. The method is formulated and discussed in detail by means of\nvarious numerical experiments, demonstrating its utility and scalability."
    },
    {
        "anchor": "Atomic-scale investigation of the irradiation-resistant effect of\n  symmetric tilt grain boundaries of Fe-Ni-Cr alloy: In this paper, the Fe-20Ni-25Cr alloy that is used for fuel cladding or\npressure vessels with various grain boundaries (GBs) was investigated by\nemploying molecular dynamics simulations. The bi-crystals comprised of\n{\\Sigma}3(111), {\\Sigma}3(112), {\\Sigma}9(114), {\\Sigma}11(113),\n{\\Sigma}19(116), and {\\Sigma}17(223) types GBs were considered to\nsystematically examine the interplay between irradiation defects, irradiation\nmicrostructure evolution under stress, and irradiation mechanical properties\nwith irradiation intensity, coincidence site lattice parameter, tilt angle, and\nGB thickness. It is found that irradiated vacancies and interstitials are\nannihilated by competitive GB absorption and recombination. Bias absorption of\ninterstitials is observed for most bi-crystals except {\\Sigma}3(111) and\n{\\Sigma}11(113) at 15 keV incident energy, and results in abundant residual\nvacancies clusters in grain interior. In addition, different GBs exhibit quite\ndiverse irradiation defect sink ability, and the number of residual vacancies\nis inversely related to the GB thickness, where {\\Sigma}3(111) and\n{\\Sigma}11(113) GBs with narrow GB thickness are weak in defect absorption and\nthe others are strong. Furthermore, uniaxial tensile simulations perpendicular\nto the GB reveal that all of the mechanical performance of bi-crystals\ndeteriorates after irradiation, which originates from dislocation propagation\nfacilitated by irradiation defect clusters. In particular, regardless of\nwhether the irradiation is applied, the maximum tensile strain, toughness, and\nYoungs modulus are monotonically correlated with GB tilt angle, while the\nultimate tensile strength is stable for larger GB CSL parameter. Finally, on\nthe basis of the evolution of the irradiation defects, microstructures, and\nmechanical performances, we proposed guidelines of rational design of\nirradiation-resistant Fe-Ni-Cr alloy.",
        "positive": "Quantitative comparison of electrically induced spin and orbital\n  polarizations in heavy-metal/3d-metal bilayers: Electrical control of magnetization is of crucial importance for integrated\nspintronics devices. Spin-orbit torques (SOT) in heavy-metal/ferromagnetic\nheterostructures have emerged as promising tool to achieve efficiently\ncurrent-induced magnetization reversal. However, the microscopic origin of the\nSOT is being debated,with the spin Hall effect (SHE) due to nonlocal spin\ncurrents and the spin Rashba-Edelstein effect (SREE) due to local spin\npolarization at the interface being the primary candidates. We investigate the\nelectrically induced out-of-equilibrium spin and orbital polarizations in pure\nPt films and in Pt/3d-metal (Co, Ni, Cu) bilayer films using ab initio\nelectronic structure methods and linear-response theory. We compute\natom-resolved response quantities that allow us to identify the induced\nspin-polarization contributions that lead to fieldlike SOTs, mostly associated\nwith the SREE, and dampinglike (DL) SOTs, mostly associated with the SHE, and\ncompare their relative magnitude, dependence on the magnetization direction, as\nwell as their Pt-layer thickness dependence. We find that both the FL and DL\ncomponents contribute to the resulting SOT at the Pt/Co and Pt/Ni interfaces,\nwith the former contributions being larger at the Pt interface layer and the\nlatter larger in the Co or Ni layers. Our calculations show that the\nelectrically-induced transverse orbital polarization is exceedingly larger than\nthe induced spin polarization and present even without spin-orbit coupling, in\ncontrast to the spin polarization."
    },
    {
        "anchor": "A numerical strategy for coarse-graining two-dimensional atomistic\n  models at finite temperature: the membrane case: We present a numerical strategy to compute ensemble averages of\ncoarse-grained two-dimensional membrane-like models. The approach consists in\ngeneralizing to these two-dimensional models a one-dimensional strategy exposed\nin [Blanc, Le Bris, Legoll, Patz, JNLS 2010], which is based on applying the\nergodic theorem to Markov chains. This may be considered as a first step\ntowards computing the constitutive law associated to such models, in the\nthermodynamic limit.",
        "positive": "Ab Initio Physics Calculations for Borophene for Electronic Devices: Moving beyond traditional 2D materials is now desirable to have switching\ncapabilities (e.g., transistors). Here we propose using borophene because, as\nwe will show in this letter, obtaining regions of the electronic bandstructure\nwhich act as valence and conduction bands, with an apparent bandgap, may be\nobtainable in the foreseeable future. Here for particular allotropes of\nborophene, density of states (DOS) and electronic bandstructure diagrams with\nE(k) vs k are found with much improved accuracy by ab initio quantum\ncalculations using hybrid functionals of several types. This procedure should\nallow much better insight into how to obtain acceptable materials."
    },
    {
        "anchor": "Observation of Rydberg exciton polaritons and their condensate in a\n  perovskite cavity: The condensation of half-light half-matter exciton polaritons in\nsemiconductor optical cavities is a striking example of macroscopic quantum\ncoherence in a solid state platform. Quantum coherence is possible only when\nthere are strong interactions between the exciton polaritons provided by their\nexcitonic constituents. Rydberg excitons with high principle value exhibit\nstrong dipole-dipole interactions in cold atoms. However, polaritons with the\nexcitonic constituent that is an excited state, namely Rydberg exciton\npolaritons (REPs), have not yet been experimentally observed. Here, for the\nfirst time, we observe the formation of REPs in a single crystal CsPbBr3\nperovskite cavity without any external fields. These polaritons exhibit strong\nnonlinear behavior that leads to a coherent polariton condensate with a\nprominent blue shift. Furthermore, the REPs in CsPbBr3 are highly anisotropic\nand have a large extinction ratio, arising from the perovskite's orthorhombic\ncrystal structure. Our observation not only sheds light on the importance of\nmany-body physics in coherent polariton systems involving higher-order excited\nstates, but also paves the way for exploring these coherent interactions for\nsolid state quantum optical information processing.",
        "positive": "Aluminum and Gallium Distribution in the Lu3(Al5-xGax)O12:Ce\n  Multicomponent Garnet Scintillators Investigated by the Solid-State NMR and\n  DFT calculations: Distribution of aluminum and gallium atoms over the tetrahedral and\noctahedral sites in the garnet structure was studied in the mixed\nLu3Al5-xGaxO12 crystals using the 27Al and 71Ga MAS NMR together with the\nsingle crystal 71Ga NMR. The experimental study was accompanied by theoretical\ncalculations based on the density functional theory in order to predict the\ntendency in substitutions of Al by Ga in the mixed garnets. Both experimental\nand theoretic results show a non-uniform distribution of Al and Ga over the\ntetrahedral and octahedral sites in the garnet structure, with strong\npreferences for Ga, having larger ionic radius than Al, to occupy the\ntetrahedral site with smaller volume in the garnet structure. The quadrupole\ncoupling constants and chemical shift parameters for Al and Ga nuclei have been\ndetermined for all the studied compounds as well as electric field gradients at\nAl and Ga nuclei were calculated in the framework of the density functional\ntheory."
    },
    {
        "anchor": "Ab initio study of bilateral doping within the MoS2-NbS2 system: We present a systematic study on the stability and the structural and\nelectronic properties of mixed molybdenum-niobium disulphides. Using density\nfunctional theory we investigate bilateral doping with up to 25 % of MoS2\n(NbS2) by Nb (Mo) atoms, focusing on the precise arrangement of dopants within\nthe host lattices. We find that over the whole range of considered\nconcentrations, Nb doping of MoS2 occurs through a substitutional mechanism.\nFor Mo in NbS2 both interstitial and substitutional doping can co-exist,\ndepending upon the particular synthesis conditions. The analysis of the\nstructural and electronic modifications of the perfect bulk systems due to the\ndoping is presented. We show that substitutional Nb atoms introduce electron\nholes to the MoS2, leading to a semiconductor-metal transition. On the other\nhand, the Mo doping of Nb2, does not alter the metallic behavior of the initial\nsystem. The results of the present study are compared with available\nexperimental data on mixed MoS2-NbS2 (bulk and nanoparticles).",
        "positive": "Structural, chemical and optical characterizations of nanocrystallized\n  AlN:Er thin films prepared by r.f. magnetron sputtering: Nanocrystalline n-AlN:Er thin films were deposited on (001) Silicon\nsubstrates by r. f. magnetron sputtering at room temperature to study the\ncorrelation between 1.54 $\\mu$m IR photoluminescence (PL) intensity, AlN\ncrystalline structure and Er concentration rate. This study first presents how\nEnergy-Dispersive Spectroscopy of X-rays (EDSX) Er Cliff Lorimer sensitivity\nfactor alpha = 5 is obtained by combining EDSX and electron probe micro\nanalysis (EPMA) results on reference samples. It secondly presents the relative\nPL intensities of nanocrystallized samples prepared with identical sputtering\nparameters as a function of the Er concentration. The structure of crystallites\nin AlN films is observed by transmission electron microscopy."
    },
    {
        "anchor": "Abnormal CO2 and H2O Diffusion in CALF-20(Zn) Metal-Organic Framework\n  Angstropores: Carbon mitigation is one challenging issue that the world is facing. To\ntackle deleterious impacts of CO2, processes emerged, including chemisorption\nfrom amine based solvents, and more recently physisorption in porous solids.\nWhile CO2 capture from amine is more mature, this process is corrosive and\ndetrimental for environment. Physisorption in Metal-Organic Frameworks (MOFs)\nis currently attracting a considerable attention, however the selection of the\noptimum sorbent is still challenging. While CO2 adsorption by MOFs have been\nwidely explored from a thermodynamics standpoint, dynamical aspects remain less\nexplored. CALF-20(Zn) MOF was recently proposed as a promising alternative to\nthe commercially used CO2 13X zeolite sorbents, however, in-depth understanding\nof microscopic mechanisms originating its good performance still have to be\nachieved. In this report, we deliver a microscopic insight of CO2 and H2O in\nCALF-20(Zn) by atomistic simulations. CALF-20(Zn) revealed to exhibit\nunconventional guest-host behaviors that give rise to abnormal thermodynamic\nand diffusion. The hydrophobic nature of the solid leads to a low water\nadsorption enthalpy at low loading followed by a gradual increase, driven by\nstrong water hydrogen bonds, found to arrange as quasi 1D water wires in MOF\nporosity, recalling water behavior in carbon nanotubes and aquaporins. While no\nsuper-diffusion found, this behavior was shown to impact diffusion along with\nguests loading, with a minimum correlated with inflection point of adsorption\nisotherm corresponding to wires formation. Interestingly, diffusion of both CO2\nand H2O were also found to be of the same order of magnitude with similar\nnon-linear behaviors.",
        "positive": "High-temperature phonons in h-BN: momentum-resolved vibrational\n  spectroscopy and theory: Vibrations in materials and nanostructures at sufficiently high temperatures\nresult in anharmonic atomic displacements, which leads to new phenomena such as\nthermal expansion and multiphonon scattering processes, with a profound impact\non temperature-dependent material properties including thermal conductivity,\nphonon lifetimes, nonradiative electronic transitions, and phase transitions.\nNanoscale momentum-resolved vibrational spectroscopy, which has recently become\npossible on monochromated scanning-transmission-electron microscopes, is a\nunique method to probe the underpinnings of these phenomena. Here we report\nmomentum-resolved vibrational spectroscopy in hexagonal boron nitride at\ntemperatures of 300, 800, and 1300 K across three Brillouin zones (BZs) that\nreveals temperature-dependent phonon energy shifts and demonstrates the\npresence of strong Umklapp processes. Density-functional-theory calculations of\ntemperature-dependent phonon self-energies reproduce the observed energy shifts\nand identify the contributing mechanisms."
    },
    {
        "anchor": "High throughput inverse design and Bayesian optimization of\n  functionalities: spin splitting in two-dimensional compounds: The development of spintronic devices demands the existence of materials with\nsome kind of spin splitting (SS). In this Data Descriptor, we build a database\nof ab initio calculated SS in 2D materials. More than that, we propose a\nworkflow for materials design integrating an inverse design approach and a\nBayesian inference optimization. We use the prediction of SS prototypes for\nspintronic applications as an illustrative example of the proposed workflow.\nThe prediction process starts with the establishment of the design principles\n(the physical mechanism behind the target properties), that are used as filters\nfor materials screening, and followed by density functional theory (DFT)\ncalculations. Applying this process to the C2DB database, we identify and\nclassify 358 2D materials according to SS type at the valence and/or conduction\nbands. The Bayesian optimization captures trends that are used for the\nrationalized design of 2D materials with the ideal conditions of band gap and\nSS for potential spintronics applications. Our workflow can be applied to any\nother material property.",
        "positive": "On the thermo-elastostatics of heterogeneous materials. II. Analyze and\n  generalization of some basic hypotheses: One considers linearly thermoelastic composite media, which consist of a\nhomogeneous matrix containing a statistically homogeneous random set of\nellipsoidal uncoated or coated inclusions. Effective properties (such as\ncompliance and thermal expansion) as well as the first statistical moments of\nstresses in the phases are estimated for the general case of nonhomogeneity of\nthe thermoelastic inclusion properties. At first, one shortly reproduces both\nthe basic assumptions and propositions of micromechanics used in most popular\nmethods, namely: effective field hypothesis, quasi-crystallite approximation,\nand the hypothesis of \"ellipsoidal symmetry\". The explicit new representations\nof the effective thermoelastic properties and stress concentration factor are\nexpressed through some building blocks described by numerical solutions for\nboth the one and two inclusions inside the infinite medium subjected to both\nthe homogeneous and inhomogeneous remote loading. The method uses as a\nbackground the new general integral equation proposed in the accompanied paper\nand makes it possible to abandon the basic concepts of micromechanics mentioned\nabove. The results of this abandonment are quantitatively estimated for some\nmodeled composite reinforced by aligned continously inhomogeneous fibers. Some\nnew effects are detected that are impossible in the framework of a classical\nbackground of micromechanics."
    },
    {
        "anchor": "The Adoption of Image-Driven Machine Learning for Microstructure\n  Characterization and Materials Design: A Perspective: The recent surge in the adoption of machine learning techniques for materials\ndesign, discovery, and characterization has resulted in an increased interest\nand application of Image Driven Machine Learning (IDML) approaches. In this\nwork, we review the application of IDML to the field of materials\ncharacterization. A hierarchy of six action steps is defined which\ncompartmentalizes a problem statement into well-defined modules. The studies\nreviewed in this work are analyzed through the decisions adopted by them at\neach of these steps. Such a review permits a granular assessment of the field,\nfor example the impact of IDML on materials characterization at the nanoscale,\nthe number of images in a typical dataset required to train a semantic\nsegmentation model on electron microscopy images, the prevalence of transfer\nlearning in the domain, etc. Finally, we discuss the importance of\ninterpretability and explainability, and provide an overview of two emerging\ntechniques in the field: semantic segmentation and generative adversarial\nnetworks.",
        "positive": "Creep failures in heterogeneous materials: We present creep experiments on fiber composite materials with controlled\nheterogeneity. Recorded strain rates and acoustic emission rates exhibit a\npower law relaxation in the primary creep regime (Andrade law) followed by a\npower law acceleration up to rupture over up to four decades in time. We\ndiscover that the failure time is proportional to the duration of the primary\ncreep regime, showing the interplay between the two regimes and offering a\nmethod of rupture prediction. These experimental results are rationalized by a\nmean-field model of representative elements with nonlinear visco-elastic\nrheology and with a large heterogeneity of strengths."
    },
    {
        "anchor": "Theoretical insights for Improving the Schottky-barrier Height at the\n  Ga$_2$O$_3$/Pt Interface: In this work we study the Schottky barrier height (SBH) at the junction\nbetween $\\beta$-Ga$_2$O$_3$ and platinum, a system of great importance for the\nnext generation of high-power and high-temperature electronic devices.\nSpecifically, we obtain interfacial atomic structures at different orientations\nusing our structure matching algorithm and compute their SBH using electronic\nstructure calculations based on hybrid density functional theory. The\norientation and strain of platinum are found to have little impact on the\nbarrier height. In contrast, we find that decomposed water (H.OH), which could\nbe present at the interface from Ga$_2$O$_3$ substrate preparation, has a\nstrong influence on the SBH, in particular in the ($\\overline{2}$01)\norientation. The SBH can range from $\\sim$2 eV for the pristine interface to\nnearly zero for the full H.OH coverage. This result suggests that SBH of\n$\\sim$2~eV can be achieved for the Ga$_2$O$_3$($\\overline{2}$01)/Pt junction\nusing the substrate preparation methods that can reduce the amount of adsorbed\nwater at the interface.",
        "positive": "Target domains in nanometric Permalloy disks with columnar structure: We conducted a thorough experimental and numerical study of the micromagnetic\nproperties of Permalloy (Ni$_{80}$Fe$_{20}$) microdisks exhibiting target\ndomain structures at remanence. Vortex configurations are quite common in such\nmicrodisks and correspond to an in-plane flux closure configuration of\ncylindrical symmetry with an out-of-plane magnetized core. In contrast, target\ndomain configuration are observed in thicker microdisks and are characterized\nby a vortex configuration of the in-plane component of the magnetization\nsuperposed to an out-of-plane component of magnetization which oscillates as a\nfunction of the distance to the microdisk center resulting in the formation of\nconcentric domains. The ratio of the out-of-plane oscillatory component of the\nmagnetization to the in-plane vortex one increases with the thickness of the\nmicrodisk. Hysteresis loops were measured under in-plane and out-of-plane\nfield. The results at remanence and under magnetic field could be interpreted\nby micromagnetic simulations in which the microdisks were described as an\nassembly of partially coupled columns representing the granular nanostructure\nof the films from which the microdisks were patterned. Quite original\nmagnetization processes take place in these microdisks exhibiting target domain\nremanent configuration. These include in particular entire flipping of the\ndomain configuration and annihilation/creation of ring domains."
    },
    {
        "anchor": "Investigation of the mechanism of the anomalous Hall effects in\n  Cr2Te3/(BiSb)2(TeSe)3 heterostructure: The interplay between ferromagnetism and the non-trivial topology has\nunveiled intriguing phases in the transport of charges and spins. For example,\nit is consistently observed the so-called topological Hall effect (THE)\nfeaturing a hump structure in the curve of the Hall resistance (Rxy) vs. a\nmagnetic field (H) of a heterostructure consisting of a ferromagnet (FM) and a\ntopological insulator (TI). The origin of the hump structure is still\ncontroversial between the topological Hall effect model and the multi-component\nanomalous Hall effect (AHE) model. In this work, we have investigated a\nheterostructure consisting of BixSb2-xTeySe3-y (BSTS) and Cr2Te3 (CT), which\nare well-known TI and two-dimensional FM, respectively. By using the so-called\nminor-loop measurement, we have found that the hump structure observed in the\nCT/BSTS is more likely to originate from two AHE channels. Moreover, by\nanalyzing the scaling behavior of each amplitude of two AHE with the\nlongitudinal resistivities of CT and BSTS, we have found that one AHE is\nattributed to the extrinsic contribution of CT while the other is due to the\nintrinsic contribution of BSTS. It implies that the proximity-induced\nferromagnetic layer inside BSTS serves as a source of the intrinsic AHE,\nresulting in the hump structure explained by the two AHE model.",
        "positive": "The Insulating State of Matter: A Geometrical Theory: In 1964 W. Kohn published the milestone paper \"Theory of the insulating\nstate'\", according to which insulators and metals differ in their ground state.\nEven before the system is excited by any probe, a different organization of the\nelectrons is present in the ground state and this is the key feature\ndiscriminating between insulators and metals. However, the theory of the\ninsulating state remained somewhat incomplete until the late 1990s; this review\naddresses the recent developments. The many-body ground wavefunction of any\ninsulator is characterized by means of geometrical concepts (Berry phase,\nconnection, curvature, Chern number, quantum metric). Among them, it is the\nquantum metric which sharply characterizes the insulating state of matter. The\ntheory deals on a common ground with several kinds of insulators: band\ninsulators, Mott insulators, Anderson insulators, quantum Hall insulators,\nChern and topological insulators"
    },
    {
        "anchor": "Mechanical behaviour of additively manufactured Ti6Al4V meta-crystals\n  containing multi-scale hierarchical lattice structures: The mimicry of crystalline microstructure at meso-scale creates a new class\nof architected materials, termed meta-crystals, and offers effective ways to\nsignificantly improve the toughness and eliminate the post-yield collapse of\narchitected materials. This study investigated the mechanical behaviour of\npolygrain-like meta-crystals fabricated from Ti6Al4V by laser powder bed\nfusion. The mechanical behaviour of Ti6Al4V meta-crystals is governed by\nlattice structures across length-scales: the crystalline microstructure,\narchitected crystal-like mesostructures and the quality of lattice struts. Due\nto the intricate architecture, significant processing defects were seen in the\nprinted meta-crystals, in particular notch-like defects due to lack of fusion\nat the free surface of struts. Such defects raised stress concentration and\nreduced the load-bearing area of struts, hence significantly weakening the\nlattice struts. In addition, the as-printed condition was brittle due to the\npresence of acicular alpha' martensites. The defects and the as-printed\nbrittleness led to the premature fracture of struts and compromised the\nbenefits of the crystal-inspired mesostructures. The study subsequently\nconducted multiple measures to resolve this issue: increasing the strut\ndiameter to reduce the influence of the process defects, and annealing to\nrelieve internal stresses and regain ductility. The combination of the increase\nin strut diameter and annealing successfully enabled the crystal-like\narchitected mesostructure to effectively improve the toughness of the\nmeta-crystals.",
        "positive": "High magnetic anisotropy and magnetocaloric effects in single crystal\n  Cr$_2$Te$_3$: We report a systematic investigation of anisotropic magnetocaloric effects in\nsingle crystal Cr$_2$Te$_3$. Single crystal samples are synthesized by chemical\nvapor transport and characterized by x-ray and Laue diffraction methods. The\nmaximum magnetic entropy change $-\\Delta S_{\\text M}^{\\text{max}}$ is 4.50 J\nkg$^{-1}$ K$^{-1}$ for the easy c-axis (3.36 J kg$^{-1}$ K$^{-1}$ for the hard\nab-plane) and the relative cooling power RCP is 296.7 J kg$^{-1}$ for the easy\nc-axis (183.84 J kg$^{-1}$ for the hard axis ab-plane) near the Curie\ntemperature for a magnetic field change of 9 T. The magneto-crystalline\nanisotropy constant K$_u$ is estimated to be 486.92 kJ m$^{-3}$ at 146 K,\ndecreasing to 148.60 kJ m$^{-3}$ at 168 K. Meanwhile, the maximum of the\nrotational magnetic entropy change $\\Delta S_{\\text M}^{\\text R}(T, H)$ between\nthe c-axis and the ab-plane is about 1.14 J kg$^{-1}$K$^{-1}$ for\nmagnetic-field change of 9 T. The critical exponents are estimated by analyzing\nmagnetocaloric effects, which indicate 2D-Ising type magnetic system. The\naccuracy of estimated critical exponents is verified by scaling analysis. The\nmaximum magnetic entropy change $-\\Delta S_{\\text M}^{\\text{max}}$\n$\\approx$5.25 J kg$^{-1}$ K$^{-1}$ (along the c-axis) and the corresponding\nadiabatic temperature change $\\Delta T_{\\text{ad}}$ $\\approx$3.31 K (along the\nc-axis) are estimated by analyzing heat capacity measurements with a magnetic\nfield up to 9 Tesla."
    },
    {
        "anchor": "Fe-C and Fe-H systems at pressures of the Earth's inner core: The solid inner core of the Earth is predominantly composed of iron alloyed\nwith several percent Ni and some lighter elements, Si, S, O, H, and C being the\nprime candidates. There have been a growing number of papers investigating C\nand H as possible light elements in the core, but the results are\ncontradictory. Here, using ab initio simulations, we study the Fe-C and Fe-H\nsystems at inner core pressures (330-364 GPa). Using the evolutionary structure\nprediction algorithm USPEX, we have determined the lowest-enthalpy structures\nof possible carbides (FeC, Fe2C, Fe3C, Fe4C, FeC2, FeC3, FeC4 and Fe7C3) and\nhydrides (Fe4H, Fe3H, Fe2H, FeH, FeH2, FeH3, FeH4) and have found that Fe2C\n(Pnma) is the most stable iron carbide at pressures of the inner core, while\nFeH, FeH3 and FeH4 are stable iron hydrides at these conditions. For Fe3C, the\ncementite structure (Pnma) and the Cmcm structure recently found by random\nsampling are less stable than the I-4 and C2/m structures found here. We found\nthat FeH3 and FeH4 adopt chemically interesting thermodynamically stable\nstructures, in both compounds containing trivalent iron. The density of the\ninner core can be matched with a reasonable concentration of carbon, 11-15\nmol.percent (2.6-3.7 wt.percent) at relevant pressures and temperatures. This\nconcentration matches that in CI carbonaceous chondrites and corresponds to the\naverage atomic mass in the range 49.3-51.0, in close agreement with inferences\nfrom the Birch's law for the inner core. Similarly made estimates for the\nmaximum hydrogen content are unrealistically high, 17-22 mol.percent (0.4-0.5\nwt.percent), which corresponds to the average atomic mass in the range\n43.8-46.5. We conclude that carbon is a better candidate light alloying element\nthan hydrogen.",
        "positive": "Multiferroic materials and magnetoelectric physics: symmetry,\n  entanglement, excitation, and topology: Multiferroics are those materials with more than one ferroic order, and\nmagnetoelectricity refers to the mutual coupling between magnetism and\nelectricity. The discipline of multiferroicity has never been so highly active\nas that in the first decade of the twenty-first century, and it has become one\nof the hottest disciplines of condensed matter physics and materials science. A\nseries of milestones and steady progress in the past decade have enabled our\nunderstanding of multiferroic physics substantially comprehensive and profound,\nwhich is further pushing forward the research frontier of this exciting area.\nThe availability of more multiferroic materials and improved magnetoelectric\nperformance are approaching to make the applications within reach. While\nseminal review articles covering the major progress before 2010 are available,\nan updated review addressing the new achievements since that time becomes\nimperative. In this review, following a concise outline of the basic knowledge\nof multiferroicity and magnetoelectricity, we summarize the important research\nactivities on multiferroics, especially magnetoelectricity and related physics\nin the last six years. We consider not only single-phase multiferroics but also\nmultiferroic heterostructures. We address the physical mechanisms regarding\nmagnetoelectric coupling so that the backbone of this divergent discipline can\nbe highlighted. A series of issues on lattice symmetry, magnetic ordering,\nferroelectricity generation, electromagnon excitations, multiferroic domain\nstructure and domain wall dynamics, and interfacial coupling in multiferroic\nheterostructures, will be revisited in an updated framework of physics. In\naddition, several emergent phenomena and related physics, including magnetic\nskyrmions and generic topological structures associated with magnetoelectricity\nwill be discussed."
    },
    {
        "anchor": "Structural ordering driven anisotropic magnetoresistance, anomalous Hall\n  resistance and its topological overtones in full-Heusler Co2MnSi thin films: We report the evolution of crystallographic structure, magnetic ordering and\nelectronic transport in thin films of full-Heusler alloy Co$_2$MnSi deposited\non (001) MgO with annealing temperatures ($T_A$). By increasing the $T_A$ from\n300$^\\circ$C to 600$^\\circ$C, the film goes from a disordered nanocrystalline\nphase to $B2$ ordered and finally to the $L2_1$ ordered alloy. The saturation\nmagnetic moment improves with structural ordering and approaches the\nSlater-Pauling value of $\\approx 5.0 \\mu_B$ per formula unit for $T_A$ =\n600$^\\circ$C. At this stage the films are soft magnets with coercive and\nsaturation fields as low as $\\approx$ 7 mT and 350 mT, respectively. Remarkable\neffects of improved structural order are also seen in longitudinal resistivity\n($\\rho_{xx}$) and residual resistivity ratio. A model based upon electronic\ntransparency of grain boundaries illucidates the transition from a state of\nnegative $d\\rho/dT$ to positive $d\\rho/dT$ with improved structural order. The\nHall resistivity ($\\rho_{xy}$) derives contribution from the normal scattering\nof charge carriers in external magnetic field, the anomalous effect originating\nfrom built-in magnetization and a small but distinct topological Hall effect in\nthe disordered phase. The carrier concentration ($n$) and mobility ($\\mu$) have\nbeen extracted from the high field $\\rho_{xy}$ data. The highly ordered films\nare characterized by $n$ and $\\mu$ of 1.19$\\times$ 10$^{29}$ m$^{-3}$ and 0.4\ncm$^2V^{-1}s^{-1}$ at room temperature. The dependence of $\\rho_{xy}$ on\n$\\rho_{xx}$ indicates the dominance of skew scattering in our films, which\nshows a monotonic drop on raising the $T_A$. The topological Hall effect is\nanalyzed for the films annealed at 300$^\\circ$C. ......",
        "positive": "Stochastic modeling of chaotic masonry via mesostructural\n  characterization: The purpose of this study is to explore three numerical approaches to the\nelastic homogenization of disordered masonry structures with moderate\nmeso/macro-lengthscale ratio. The methods investigated include a representative\nof perturbation methods, the Karhunen-Lo\\`{e}ve expansion technique coupled\nwith Monte-Carlo simulations and a solver based on the Hashin-Shtrikman\nvariational principles. In all cases, parameters of the underlying random field\nof material properties are directly derived from image analysis of a real-world\nstructure. Added value as well as limitations of individual schemes are\nillustrated by a case study of an irregular masonry panel."
    },
    {
        "anchor": "Measurement independent magnetocaloric effect in Mn-rich\n  Mn-Fe-Ni-Sn(Sb/In) Heusler alloys: We report a systematic study on the magneto-structural transition in Mn-rich\nFe-doped Mn-Fe-Ni-Sn(Sb/In) Heusler alloys by keeping the total valence\nelectron concentration (e/a ratio) fixed. The martensitic transition (MT)\ntemperature is found to shift by following a proportional relationship with the\ne/a ratio of the magnetic elements alone. The magnetic entropy change across MT\nfor a selected sample (Mn49FeNi40Sn9In) has been estimated from three different\nmeasurement methods (isofield magnetization (M) vs temperature (T), isothermal\nM vs field (H) and heat capacity (HC) vs T). We observed that though the peak\nvalue of magnetic entropy change changes with the measurement methods, the\nbroadened shape of the magnetic entropy change vs T curves and the\ncorresponding cooling power (~140 Jkg-1) remains invariant. The equivalent\nadiabatic temperature change ~ -2.6 K has been obtained from indirect\nmeasurements of temperature change. Moreover, an exchange bias field ~ 783 Oe\nat 5 K and a magnetoresistance of -30% are also obtained in one of these\nmaterials.",
        "positive": "Myths about new ultrahard phases: Why materials that are significantly\n  superior to diamond in elastic moduli and hardness are impossible?: Reports published in the last 25 years on the synthesis of carbon-based\nmaterials significantly superior to diamond in hardness and elastic properties\nhave been critically examined, and three groups of recently appearing myths\nhave been analyzed. The first group concerns the possibility of producing\nmaterials with bulk moduli much higher than that of diamond. The second group\nregards to \"experimentally measured\" hardness significantly higher than that of\ndiamond. Myths of the third group state that quantum confinement effects\nsupposedly provide \"theoretical\" foundations for a several-fold (!) increase in\nthe hardness of covalent materials. The fundamental impossibility of\nsynthesizing materials with elastic moduli noticeably exceeding the diamond\nvalue under normal conditions has been demonstrated. The problems of hardness\nmeasuring have been discussed; it was shown that the formation of obstacles for\nmotion of dislocations can allow increasing the measured hardness of superhard\nmaterials by 20-40%. It was demonstrated that other hypothetical ways for\nhardness increase, e.g. owing to quantum confinement have no any real physical\ngrounds. The superior mechanical properties of diamond are due to reliably\nestablished physical laws. Accordingly, any statements on the possibility of\nobtaining materials with elastic characteristics and/or hardness several times\nhigher than the corresponding values for diamond cannot be considered as\nscientifically reliable."
    },
    {
        "anchor": "Active Learning Sensitivity Analysis of $\u03b3^\\prime$(L1$_2$)\n  Precipitate Morphology of Ternary Co-Based Superalloys: To better understand the equilibrium $\\gamma^\\prime$(L1$_2$) precipitate\nmorphology in Co-based superalloys, a phase field modeling sensitivity analysis\nis conducted to examine how four phase-field parameters [initial Co\nconcentration ($c_0$), double-well barrier height ($\\omega$), gradient energy\ndensity coefficient ($\\kappa$), and lattice misfit strain ($\\epsilon_{\\rm\nmisfit}$)] influence the $\\gamma^\\prime$(L1$_2$) precipitate size and\nmorphology. Gaussian Process Regression (GPR) models are used to fit the sample\npoints and to generate surrogate models for both precipitate size and\nmorphology. In an Active Learning approach, a Bayesian Optimization algorithm\nis coupled with the GPR models to suggest new sample points to calculate and\nefficiently update the models based on a reduction of uncertainty. The\nalgorithm has a user-defined objective, which controls the balance between\nexploration and exploitation for new suggested points. Our methodology provides\na qualitative and quantitative relationship between the $\\gamma^\\prime$(L1$_2$)\nprecipitate size and morphology and the four phase-field parameters, and\nconcludes that the most sensitive phase-field parameter for precipitate size\nand morphology is the initial Co concentration ($c_0$) and the double-well\nbarrier height ($\\omega$), respectively. We note that the GPR model for\nprecipitate morphology required adding a noise tolerance in order to avoid\noverfitting due to irregularities in some of the simulated equilibrium\n$\\gamma^\\prime$(L1$_2$) precipitate morphology.",
        "positive": "The 3d and 5d electronic structures and orbital hybridization in Ba- and\n  Ca-doped La2CoIrO6 double perovskite: Here we present a detailed investigation of the Co and Ir local electronic\nstructures in La1.5A0.5CoIrO6 (A = Ba, Ca) compounds in order to unravel the\norbital hybridization mechanism in these CoIr-based double perovskites. Our\nresults of x-ray powder diffraction, ac and dc magnetization, Co and Ir\nL2,3-edges and Co K-edge x-ray absorption spectroscopy and x-ray magnetic\ncircular dichroism suggest a competition between magnetic interactions. A\ndominant antiferromagnetic coupling is found to be responsible for the\nferrimagnetic behavior observed for A = Ca below approximately 96 K, the\ncompeting magnetic phases and the cationic disorder in this compound giving\nrise to a spin-glass state at low temperatures. For the A = Ba, on the other\nhand, there is no evidence of long range order down to its spin-glass\ntransition temperature. The remarkably different magnetic properties observed\nbetween these two compounds is discussed in terms of the structural distortion\nthat alters the strength of the Co - Ir couplings, with a relevant role played\nby the Co 3d eg - Ir 5d j = 1/2 hybridization."
    },
    {
        "anchor": "Sliding Over a Phase Transition: The effects of a displacive structural phase transition on sliding friction\nare in principle accessible to nanoscale tools such as the Atomic Force\nMicroscopy, yet they are still surprisingly unexplored. We present model\nsimulations demonstrating and clarifying the mechanism and potential impact of\nthese effects. A structural order parameter inside the material will yield a\ncontribution to stick-slip friction that is nonmonotonic as temperature crosses\nthe phase transition, peaking at the critical Tc where critical fluctuations\nare strongest, and the sliding-induced order parameter local flips from one\nvalue to another more numerous. Accordingly, the friction below Tc is larger\nwhen the order parameter orientation is such that flips are more effectively\ntriggered by the slider. The observability of these effects and their use for\nfriction control are discussed, for future application to sliding on the\nsurface of and ferro- or antiferro-distortive materials.",
        "positive": "Functional surfaces of laser-microstructured silicon coated with\n  thermoresponsive PS/PNIPAM polymer blends: switching reversibly between\n  hydrophilicity and hydrophobicity: We developed functional surfaces of laser-microstructured silicon coated with\nblends of polystyrene (PS) and poly(N-isopropylacrylamide) (PNIPAM) and we\nstudy their switching wetting behavior between hydrophilicity and\nhydrophobicity. Large areas of silicon are processed with reproducible surface\nmicromorphology and spin-coated with PS/PNIPAM blends of two blend ratios. The\nwetting behavior of the surfaces is modified by the combination of surface\ntopography and surface chemistry effects. PS/PNIPAM films are casted on flat\nand microstructured silicon substrates with or without a native SiO2 layer. All\nfilms respond to the stimulus of temperature and films casted on\nmicrostructured silicon substrates with a native SiO2 layer show the highest\nthermoresponsiveness presumably because they adopt a more favorable structure.\nMicrostructuring provides a large specific area that extends the contact of\nPNIPAM chains with water molecules according to the Wenzel model, and thus\nincreasing the film thermoresponsiveness, resulting in a reversible transition\nfrom hydrophilicity to hydrophobicity upon heating. The absence of the native\nSiO2 layer from the silicon substrates affects the PS and PNIPAM arrangement in\nthe films, increasing the water contact angle both below and above the lower\ncritical solution temperature of PNIPAM and decreasing their\nthermoresponsiveness."
    },
    {
        "anchor": "Hydrogen incorporation into amorphous indium gallium zinc oxide\n  thin-film transistors: Within the subgap of amorphous oxide semiconductors like amorphous indium\ngallium zinc oxide (a-IGZO) are donor-like and acceptor-like states that\ncontrol the operational physics of optically transparent thin-film transistors\n(TFTs). Hydrogen incorporation into the channel layer of a top-gate a-IGZO TFT\nexists as an electron donor that causes an observed negative shift in the drain\ncurrent-gate voltage ($\\mathrm{I_{D} - V_{G}}$) transfer curve turn-on voltage.\nNormally, hydrogen is thought to create shallow electronic states just below\nthe conduction band mobility edge, with the donor ionization state controlled\nby equilibrium thermodynamics involving the position of the Fermi level with\nrespect to the donor ionization energy. However, hydrogen does not behave as a\nnormal donor as revealed by the subgap density of states (DoS) measured by the\nphotoconduction response of top-gate a-IGZO TFTs to within 0.3 eV of the CBM\nedge. Specifically, the DoS shows a subgap peak above the valence band mobility\nedge growing at the same rate that $\\mathrm{I_{D} - V_{G}}$ transfer curve\nmeasurements suggest that hydrogen was incorporated into the channel layer.\nSuch hydrogen donor behavior in a-IGZO is anomalous and can be understood as\nfollows: Non-bonded hydrogen ionization precedes its incorporation into the\na-IGZO network as a bonded species. Ionized hydrogen bonds to a charged\noxygen-on-an-oxygen-site anion, resulting in the formation of a defect complex\ndenoted herein as, $\\mathrm{{[{O_{O}^{2-}}{H^+}]}^{1-}}$. Formation of an\n$\\mathrm{{[{O_{O}^{2-}}{H^+}]}^{1-}}$ defect complex creates a spectrally-broad\n($\\sim$0.3 eV FWHM) distribution of electronic states observed in the bandgap\ncentered at 0.4 eV above the valence band mobility edge.",
        "positive": "Extremely Low Drift in Amorphous Phase Change Nanowire Materials: Time-dependent drift of resistance and threshold voltage in phase change\nmemory (PCM) devices is of concern as it leads to data loss. Electrical drift\nin amorphous chalcogenides has been argued to be either due to electronic or\nstress relaxation mechanisms. Here we show that drift in amorphized Ge2Sb2Te5\nnanowires with exposed surfaces is extremely low in comparison to thin-film\ndevices. However, drift in stressed nanowires embedded under dielectric films\nis comparable to thin-films. Our results shows that drift in PCM is due to\nstress relaxation and will help in understanding and controlling drift in PCM\ndevices."
    },
    {
        "anchor": "The role of slip transfer at grain boundaries in the propagation of\n  microstructurally short fatigue cracks in Ni-based superalloys: Crack initiation and propagation under high-cycle fatigue conditions have\nbeen investigated for a polycrystalline Ni-based superalloy by in-situ\nsynchrotron assisted diffraction and phase contrast tomography. The cracks\nnucleated along the longest coherent twin boundaries pre-existing on the\nspecimen surface, that were well oriented for slip and that presented a large\nelastic incompatibility across them. Moreover, the propagation of\nmicrostructurally short cracks was found to be determined by the easy slip\ntransfer paths across the pre-existing grain boundaries. This information can\nonly be obtained by characterization techniques like the ones presented here\nthat provide the full set of 3D microstructural information.",
        "positive": "Magnetic anisotropy in strained manganite films and bicrystal junctions: Transport and magnetic properties of LSMO manganite thin films and bicrystal\njunctions were investigated. Manganite films were epitaxially grown on STO,\nLAO, NGO and LSAT substrates and their magnetic anisotropy were determined by\ntwo techniques of magnetic resonance spectroscopy. Compare with cubic\nsubstrates a small (about 0.3 persentage), the anisotropy of the orthorhombic\nNGO substrate leads to a uniaxial anisotropy of the magnetic properties of the\nfilms in the plane of the substrate. Samples with different tilt of\ncrystallographic basal planes of manganite as well as bicrystal junctions with\nrotation of the crystallographic axes (RB - junction) and with tilting of basal\nplanes (TB - junction) were investigated. It was found that on vicinal NGO\nsubstrates the value of magnetic anisotropy could be varied by changing the\nsubstrate inclination angle from 0 to 25 degrees. Measurement of magnetic\nanisotropy of manganite bicrystal junction demonstrated the presence of two\nferromagnetically ordered spin subsystems for both types of bicrystal\nboundaries RB and TB. The magnitude of the magnetoresistance for TB - junctions\nincreased with decreasing temperature and with the misorientation angle even\nmisorientation of easy axes in the parts of junction does not change. Analysis\nof the voltage dependencies of bicrystal junction conductivity show that the\nlow value of the magnetoresistance for the LSMO bicrystal junctions can be\ncaused by two scattering mechanisms with the spin- flip of spin - polarized\ncarriers due to the strong electron - electron interactions in a disordered\nlayer at the bicrystal boundary at low temperatures and the spin-flip by anti\nferromagnetic magnons at high temperatures."
    },
    {
        "anchor": "Why Do Eight Units of Methylammonium Enclose PbI6 Octahedron in\n  Large-Scale Crystals of Methylammonium Lead Iodide Perovskite Solar Cell? An\n  Answer from First-Principles Study: Methylammonium lead triiodide (CH3NH3PbI3) perovskite solar cell is a gem in\nthe list of photovoltaic semiconductors. Although there are numerous\nfundamental and technological questions yet to be addressed covering various\naspects of this system for its commercialization, this study has employed\nfirst-principles DFT to model the [PbI6(CH3NH3)n]m zero-dimensional\nnanoclusters. Using the calculated binding energy landscapes, it has answered\nthe question: why the corner-sharing PbI6 octahedron is surrounded by eight\nunits of the organic cation in the large-scale supramolecular structures of the\nCH3NH3PbI3 system in 3D? The synergistic effect of the methylammonium, as well\nas the consequence of positive and negative cooperative effects associated with\nintermolecular hydrogen bonding on the supramolecular evolution of the\nCH3NH3PbI3 crystals is briefly outlined.",
        "positive": "A first-principles study of carbon-related energy levels in GaN. Part I\n  - complexes formed by substitutional/interstitial carbons and\n  gallium/nitrogen vacancies: Various forms of carbon based complexes in GaN are studied with\nfirst-principles calculations employing Heyd-Scuseria-Ernzerhof hybrid\nfunctional within the framework of density functional theory. We consider\ncarbon complexes made of the combinations of single impurities, i.e.\n$\\mathrm{C_N-C_{Ga}}$, $\\mathrm{C_I-C_N}$ and $\\mathrm{C_I-C_{Ga}}$, where\n$\\mathrm{C_N}$, $\\mathrm{C_{Ga}}$ and $\\mathrm{C_I}$ denote C substituting\nnitrogen, C substituting gallium and interstitial C, respectively, and of\nneighboring gallium/nitrogen vacancies ($\\mathrm{V_{Ga}}$/$\\mathrm{V_N}$), i.e.\n$\\mathrm{C_N-V_{Ga}}$ and $\\mathrm{C_{Ga}-V_N}$. Formation energies are\ncomputed for all these configurations with different charge states after full\ngeometry optimizations. From our calculated formation energies, thermodynamic\ntransition levels are evaluated, which are related to the thermal activation\nenergies observed in experimental techniques such as deep level transient\nspectroscopy. Furthermore, the lattice relaxation energies (Franck-Condon\nshift) are computed to obtain optical activation energies, which are observed\nin experimental techniques such as deep level optical spectroscopy. We compare\nour calculated values of activation energies with the energies of\nexperimentally observed C-related trap levels and identify the physical origins\nof these traps, which are unknown before."
    },
    {
        "anchor": "Dislocation contrast in cathodoluminescence and electron-beam induced\n  current maps on GaN(0001): We theoretically analyze the contrast observed at the outcrop of a threading\ndislocation at the GaN(0001) surface in cathodoluminescence and electron-beam\ninduced current maps. We consider exciton diffusion and recombination including\nfinite recombination velocities both at the planar surface and at the\ndislocation. Formulating the reciprocity theorem for this general case enables\nus to provide a rigorous analytical solution of this diffusion-recombination\nproblem. The results of the calculations are applied to an experimental example\nto determine both the exciton diffusion length and the recombination strength\nof threading dislocations in a free-standing GaN layer with a dislocation\ndensity of $6\\times10^{5}$~cm$^{-2}$.",
        "positive": "A Phonon Boltzmann Study of Microscale Thermal Transport in $\u03b1$-RDX\n  Cook-Off: The microscale thermal transport properties of $\\alpha$RDX are believed to be\nmajor factors in the initiation process. In this study we present a thorough\nexamination of phonon properties which dominate energy storage and transport in\n$\\alpha$RDX. The phonon lifetimes are determined for all phonon branches,\nrevealing the characteristic time scale of energy transfer amongst phonon\nmodes. The phonon parameters also serve as inputs to a full Brillouin zone\nthree dimensional phonon transport simulation in the presence of a hotspot. In\naddition to identifying the phonon mode contributions to thermal transport, and\nas N-N bond breaking is integral to disassociation, we identify phonon modes\ncorresponding to large N-N bond stretch analyzing the manner in which these\nmodes store and transfer energy."
    },
    {
        "anchor": "Numerical study of the thermoelectric power factor in ultra-thin Si\n  nanowires: Low dimensional structures have demonstrated improved thermoelectric (TE)\nperformance because of a drastic reduction in their thermal conductivity,\n{\\kappa}l. This has been observed for a variety of materials, even for\ntraditionally poor thermoelectrics such as silicon. Other than the reduction in\n{\\kappa}l, further improvements in the TE figure of merit ZT could potentially\noriginate from the thermoelectric power factor. In this work, we couple the\nballistic (Landauer) and diffusive linearized Boltzmann electron transport\ntheory to the atomistic sp3d5s*-spin-orbit-coupled tight-binding (TB)\nelectronic structure model. We calculate the room temperature electrical\nconductivity, Seebeck coefficient, and power factor of narrow 1D Si nanowires\n(NWs). We describe the numerical formulation of coupling TB to those transport\nformalisms, the approximations involved, and explain the differences in the\nconclusions obtained from each model. We investigate the effects of cross\nsection size, transport orientation and confinement orientation, and the\ninfluence of the different scattering mechanisms. We show that such methodology\ncan provide robust results for structures including thousands of atoms in the\nsimulation domain and extending to length scales beyond 10nm, and point towards\ninsightful design directions using the length scale and geometry as a design\ndegree of freedom. We find that the effect of low dimensionality on the\nthermoelectric power factor of Si NWs can be observed at diameters below ~7nm,\nand that quantum confinement and different transport orientations offer the\npossibility for power factor optimization.",
        "positive": "Topological Aspect and Quantum Magnetoresistance of $\u03b2$-Ag$_2$Te: To explain the unusual non-saturating linear magnetoresistance observed in\nsilver chalcogenides, the quantum scenario has been proposed based on the\nassumption of gapless linear energy spectrum. Here we show, by first principles\ncalculations, that $\\beta$-Ag$_2$Te with distorted anti-fluorite structure is\nin fact a topological insulator with gapless Dirac-type surface states. The\ncharacteristic feature of this new binary topological insulator is the highly\nanisotropic Dirac cone, in contrast to known examples, such as Bi$_2$Te$_3$ and\nBi$_2$Se$_3$. The Fermi velocity varies an order of magnitude by rotating the\ncrystal axis."
    },
    {
        "anchor": "Interatomic interaction at the aluminum-fullerene $\\mathrm{C}_{60}$\n  interface: We propose a model describing the interatomic interaction at the interface\nbetween fullerene $\\mathrm{C}_{60}$ and aluminum. Using the density functional\ntheory, we calculate the binding energy and the fullerene's position on the\n$\\mathrm{Al}(111)$ slab. The obtained data are applied to estimate the\nparameters of the Lennard-Jones potential for carbon and aluminum atoms, which\nis then used in molecular dynamics simulations. The results of the theoretical\nstudy of desorption of fullerenes from an aluminum substrate are in good\nagreement with those of the experiments from the literature. We also\ninvestigate the capillary effects in an aluminum melt with submerged\nfullerenes. The positive interface surface energy indicates the poor\nwettability of $\\mathrm{C}_{60}$ by the melt. The calculated value of the\ndiffusion relaxation time is approximately two orders of magnitude less than\nthe characteristic coagulation time of fullerenes. The activation character of\nthe coagulation process and the capillary nature of the interaction between\nfullerenes are discussed.",
        "positive": "Synthesis of Large-Area WS2 monolayers with Exceptional\n  Photoluminescence: Monolayer WS2 offers great promise for use in optical devices due to its\ndirect bandgap and high photoluminescence intensity. While fundamental\ninvestigations can be performed on exfoliated material, large-area and high\nquality materials are essential for implementation of technological\napplications. In this work, we synthesize monolayer WS2 under various\ncontrolled conditions and characterize the films using photoluminescence, Raman\nand x-ray photoelectron spectroscopies. We demonstrate that the introduction of\nhydrogen to the argon carrier gas dramatically improves the optical quality and\nincreases the growth area of WS2, resulting in films exhibiting mm2 coverage.\nThe addition of hydrogen more effectively reduces the WO3 precursor and\nprotects against oxidative etching of the synthesized monolayers. The\nstoichiometric WS2 monolayers synthesized using Ar+H2 carrier gas exhibit\nsuperior optical characteristics, with photoluminescence emission full width\nhalf maximum values below 40 meV and emission intensities nearly an order of\nmagnitude higher than films synthesized in a pure Ar environment."
    },
    {
        "anchor": "Origin of Spatial Charge Inhomogeneity in Graphene: In an ideal graphene sheet charge carriers behave as two-dimensional (2D)\nDirac fermions governed by the quantum mechanics of massless relativistic\nparticles. This has been confirmed by the discovery of a half-integer quantum\nHall effect in graphene flakes placed on a SiO2 substrate. The Dirac fermions\nin graphene, however, are subject to microscopic perturbations that include\ntopographic corrugations and electron density inhomogeneities (i.e. charge\npuddles). Such perturbations profoundly alter Dirac fermion behavior, with\nimplications for their fundamental physics as well as for future graphene\ndevice applications. Here we report a new technique of Dirac point mapping that\nwe have used to determine the origin of charge inhomogeneities in graphene. We\nfind that fluctuations in graphene charge density are not caused by\ntopographical corrugations, but rather by charge-donating impurities below the\ngraphene. These impurities induce unexpected standing wave patterns due to\nsupposedly forbidden back-scattering of Dirac fermions. Such wave patterns can\nbe continuously modulated by electric gating. Our observations provide new\ninsight into impurity scattering of Dirac fermions and the microscopic\nmechanisms limiting electronic mobility in graphene.",
        "positive": "Pattern formation during diffusion limited transformations in solids: We develop a description of diffusion limited growth in solid-solid\ntransformations, which are strongly influenced by elastic effects. Density\ndifferences and structural transformations provoke stresses at interfaces,\nwhich affect the phase equilibrium conditions. We formulate equations for the\ninterface kinetics similar to dendritic growth and study the growth of a stable\nphase from a metastable solid in both a channel geometry and in free space. We\nperform sharp interface calculations based on Green's function methods and\nphase field simulations, supplemented by analytical investigations. For pure\ndilatational transformations we find a single growing finger with symmetry\nbreaking at higher driving forces, whereas for shear transformations the\nemergence of twin structures can be favorable. We predict the steady state\nshapes and propagation velocities, which can be higher than in conventional\ndendritic growth."
    },
    {
        "anchor": "Manipulating the wavelength of single photons in insulating van der\n  Waals heterostructures: theory and application to bilayer hexagonal boron\n  nitride: Van der Waals heterostructures are promising for adding new functionalities\nto two-dimensional materials. In this study, we focus on single photon emitters\nhosted in one layer and adjacent to other insulating two-dimensional material.\nSpecifically, we show how the emission energy is modified by such a\nheterostructure. We developed a general approach to elucidate the mechanisms\naffecting the emission energy and studied the particular case of carbon\nsubstitutions in the hexagonal boron nitride bilayer.",
        "positive": "Ligand Additivity and Divergent Trends in Two Types of Delocalization\n  Errors from Approximate Density Functional Theory: Despite its widespread use, the predictive accuracy of density functional\ntheory (DFT) is hampered by delocalization errors, especially for correlated\nsystems such as transition-metal complexes. Two complementary tuning strategies\nhave been developed to reduce delocalization error: eliminating the global\ncurvature with respect to charge addition or removal, and computing a linear\nresponse Hubbard U as a measure of local curvature at the metal center at fixed\ncharge and applying it to the transition-metal complex in a DFT+U framework. We\ninvestigate the relationship between the two measures of delocalization error\nas we manipulate the ligand field strength by varying the number of\nstrong-field ligands in a series of heteroleptic complexes or by geometrically\nconstraining the metal-ligand bond length in homoleptic octahedral complexes.\nWe show that across these sets of complexes with varying ligand fields, an\ninverse relationship generally exists between global and local curvatures. We\nfind that effects of ligand substitution on both measures of delocalization are\ntypically additive, but the two quantities seldom coincide. The observation of\nligand additivity suggests opportunities for evaluating errors on homoleptic\ncomplexes to infer corrections for lower-symmetry complexes."
    },
    {
        "anchor": "An in-situ synchrotron diffraction study of stress relaxation in\n  titanium: Effect of temperature and oxygen on cold dwell fatigue: There is a long-standing technological problem in which a stress dwell during\ncyclic loading at room temperature in Ti causes a significant fatigue life\nreduction. It is thought that localised time dependent plasticity in soft\ngrains favourably oriented for easy plastic slip leads to load shedding and an\nincrease in stress within a neighbouring hard grain poorly oriented for easy\nslip. Quantifying this time dependent plasticity process is key to understand\nthe complex cold dwell fatigue problem. Knowing the effect of operating\ntemperature and oxygen content on cold dwell fatigue will be beneficial for\nfuture alloy design to address this problem. In this work, synchrotron X-ray\ndiffraction during stress relaxation experiments was used to characterise the\ntime dependent plastic behaviour of two commercially pure titanium samples\n(grade 1 and grade 4) with different oxygen content at 4 different temperatures\n(room temperature, 75C, 145C and 250C). Lattice strains were measured by\ntracking the diffraction peak shift from multiple crystallographic plane\nfamilies (21 diffraction rings) as a function of their orientation with respect\nto the loading direction. Critical resolved shear stress, activation energy and\nactivation volume were established for both prismatic and basal slip as a\nfunction of temperature and oxygen content by fitting a crystal plasticity\nfinite element model to the lattice strain relaxation responses measured along\nthe loading axis for five strong reflections. Higher strain rate sensitivity\nwas found to lead to higher plasticity during cold dwell.",
        "positive": "Exploiting magnetic properties of Fe doping in zirconia: In this study we explore, both from theoretical and experimental side, the\neffect of Fe doping in ZrO2 (ZrO2:Fe). By means of first principles simulation\nwe study the magnetization density and the magnetic interaction between Fe\natoms. We also consider how this is affected by the presence of oxygen\nvacancies and compare our findings with models based on impurity band and\ncarrier mediated magnetic interaction. Experimentally thin films (~ 20 nm) of\nZrO2:Fe at high doping concentration are grown by atomic layer deposition. We\nprovide experimental evidence that Fe is uniformly distributed in the ZrO2 by\ntransmission electron microscopy and energy dispersive X-ray mapping, while\nX-ray diffraction evidences the presence of the fluorite crystal structure.\nAlternating gradient force magnetometer measurements show magnetic signal at\nroom temperature, however with low magnetic moment per atom. Results from\nexperimental measures and theoretical simulations are compared."
    },
    {
        "anchor": "Local magnetic and geometric structure in Mn-doped La(Fe,Si)13: Magnetic cooling has the potential to replace conventional gas compression\nrefrigeration. Materials such as La(Fe,Si)$_{13}$ exhibit a sizeable\nfirst-order magnetocaloric effect, and it is possible to tailor the phase\ntransition towards room temperature by Mn-H-doping, resulting in a large\ntemperature range for operation. Within this work, we discuss variations of the\nelectronic and lattice structure in La(Fe,Si)$_{13}$ with increasing Mn content\nutilizing X-ray magnetic circular dichroism (XMCD) and extended X-ray\nabsorption fine structure spectroscopy (EXAFS). While XMCD shows a decrease of\nthe magnetic polarization at the Fe K edge, low-temperature EXAFS measurements\nindicate increased positional disorder in the La environment that is otherwise\nabsent for Fe and Mn. First-principles calculations link the positional\ndisorder to an enlarged Mn-Si distance -- explaining the increased positional\ndisorder in the La surrounding.",
        "positive": "Possible Coexistence of Rotational and Ferroelectric Lattice Distortions\n  in Rhombohedral PZT: The competitions between ferroelectric and rotational instabilities in\nrhombohedral PZT near x = 0.5 are investigated using first principles density\nfunctional supercell calculations. As expected, we find a strong ferroelectric\ninstability. However, we also find a substantial R-point rotational\ninstability, close to but not as deep as the ferroelectric one. This is similar\nto the situation in pure PbZrO_3. These two instabilities are both strongly\npressure dependent, but in opposite directions so that lattice compression of\nless than 1% is sufficient to change their ordering. Because of this, local\nstress fields due to B-site cation disorder may lead to coexistence of both\ntypes of instability are likely present in the alloy near the morphotropic\nphase boundary."
    },
    {
        "anchor": "Electrical transport properties of manganite powders under pressure: We have measured the electrical resistance of micrometric to nanometric\npowders of the La$_{5/8-y}$Pr$_y$Ca$_{3/8}$MnO$_3$ (LPCMO with y=0.3) manganite\nfor hydrostatic pressures up to 4 kbar. By applying different final thermal\ntreatments to samples synthesized by a microwave assisted denitration process,\nwe obtained two particular grain characteristic dimensions (40 nm and 1000 nm)\nwhich allowed us to analyze the grain size sensitivity of the electrical\nconduction properties of both the metal electrode interface with manganite (Pt\n/ LPCMO) as well as the intrinsic intergranular interfaces formed by the LPCMO\npowder, conglomerate under the only effect of external pressure. We also\nanalyzed the effects of pressure on the phase diagram of these powders. Our\nresults indicate that different magnetic phases coexist at low temperatures and\nthat the electrical transport properties are related to the intrinsic\ninterfaces, as we observe evidences of a granular behavior and an electronic\ntransport dominated by the Space Charge limited Current mechanism.",
        "positive": "Detection of Topological Materials with Machine Learning: Databases compiled using ab-initio and symmetry-based calculations now\ncontain tens of thousands of topological insulators and topological semimetals.\nThis makes the application of modern machine learning methods to topological\nmaterials possible. Using gradient boosted trees, we show how to construct a\nmachine learning model which can predict the topology of a given existent\nmaterial with an accuracy of 90%. Such predictions are orders of magnitude\nfaster than actual ab-initio calculations. Through extensive testing of\ndifferent models we determine which properties help detect topological\nmaterials. We identify the sources of our model's errors and we discuss\napproaches to overcome them."
    },
    {
        "anchor": "One-Dimensional Moir\u00e9 Physics and Chemistry in Heterostrained Bilayer\n  Graphene: Twisted bilayer graphene (tBLG) has emerged as a promising platform to\nexplore exotic electronic phases. However, the formation of moir\\'e patterns in\ntBLG has thus far been confined to the introduction of twist angles between the\nlayers. Here, we propose heterostrained bilayer graphene (hBLG), as an\nalternative avenue to access twist-angle-free moir\\'e physics via lattice\nmismatch. Using atomistic and first-principles calculations, we demonstrate\nthat uniaxial heterostrain can promote isolated flat electronic bands around\nthe Fermi level. Furthermore, the heterostrain-induced out-of-plane lattice\nrelaxation may lead to a spatially modulated reactivity of the surface layer,\npaving the way for the moir\\'e-driven chemistry and magnetism. We anticipate\nthat our findings can be readily generalized to other layered materials.",
        "positive": "Computational study of defect complexes in $\u03b2$-LiGaO$_2$ and their\n  relation to the donor-acceptor-pair recombination: Hybrid functional calculations are presented for defects in LiGaO$_2$ with\nthe fraction of non-local exchange adjusted to reproduce the recently reported\nexciton gap of 6.0 eV. We study how the defect transition levels of the main\nnative defects change with respect to the band edges compared to earlier\ncalculations which assumed a smaller band gap near 5.1 eV. In addition, we\nconsider defect complexes formed by combining the main native donor\nGa$_\\mathrm{Li}$ with the main acceptors, $V_\\mathrm{Li}$ and Li$_\\mathrm{Ga}$\nantisites as function of their relative position. These results are used to\ntentatively identify the photoluminescence bands previous assigned to\ndonor-acceptor-pair recombination."
    },
    {
        "anchor": "Molecular Dependence of the Large Seebeck Effect in \u03c4-type Organic\n  Conductors: We study the Seebeck effect in the $\\tau$-type organic conductors,\n$\\tau$-(EDO-$S$,$S$-DMEDT-TTF)$_{2}$(AuBr$_{2}$)$_{1+y}$ and\n$\\tau$-(P-$S$,$S$-DMEDT-TTF)$_{2}$(AuBr$_{2}$)$_{1+y}$, where\nEDO-$S$,$S$-DMEDT-TTF and P-$S$,$S$-DMEDT-TTF are abbreviated as OOSS and NNSS,\nrespectively, both experimentally and theoretically. Theoretically in\nparticular, we perform first-principles band calculation for the two materials\nand construct a two-orbital model, on the basis of which we calculate the\nSeebeck coefficient. We show that the calculated temperature dependence of the\nSeebeck coefficient $S$ is semi-quantitatively consistent with the experimental\nobservation. In both materials, the absolute value of the Seebeck coefficient\nis maximum at a certain temperature, and this temperature is lower for NNSS\nthan for OOSS. From a band structure viewpoint, we find that this can be traced\nback to the narrowness of the band gap between the upper and the lower\npudding-mold type bands. On the other hand, the Seebeck coefficient of NNSS in\nthe low temperature regime steeply increases with increasing temperature, which\nis due to the narrowness of the upper band. These differences in thermoelectric\nproperties demonstrate the effectiveness of controlling the band structure\nthrough molecular modification.",
        "positive": "The Ionic Kerr Effect: The Kerr effect measures a change in the refractive index proportional to the\nintensity of the applied electric field, and its ultrafast implementation has\nbeen widely used to investigate the nonlinear optical properties of many\ndifferent systems. More recently, the same mechanism has been exploited with\nterahertz light pulses to access resonant processes involving lattice\nvibrations or broken-symmetry collective modes. Here we provide experimental\nevidence and theoretical description that in insulating SrTiO3 the terahertz\nKerr effect admits a sizeable response due to lattice degrees of freedom. This\nionic contribution exploits the ability of strong terahertz pulses to excite\nmultiple infrared phonons at an intermediate step before or after the usual\noff-resonant electronic excitations responsible for the electronic Kerr effect.\nThe mechanism is identified thanks to a quantitative theoretical model of the\ntime and polarization dependence of both the electronic and phononic responses.\nSuch a ionic Kerr effect provides a tunable mechanism to modulate the\nrefractive index on ultrashort time-scales and, given the capability of\nterahertz-driven phonons to couple to order parameters and to drive materials\ntowards metastable states which may not be accessible at thermal equilibrium,\nit can be used to investigate the electron-phonon coupling across various phase\ntransitions."
    },
    {
        "anchor": "The Influence of Dimensionality on the Charge Density Wave Transition\n  and Its Application on Mid-infrared Photodetection: Two-dimensional charge density wave (CDW) materials received much attention\nfor high responsivity and broadband photodetection in recent years, due to\ntheir collective electron transport and narrow bandgap. However, the high dark\ncurrent density problem hinders their real application. Here we report a sharp\nCDW transition in quasi-1D (TaSe4)2I, and apply it for broadband\nphotodetection. Especially at mid-infrared region, the device shows both high\nphoto responsivity of 1.18e3 A/W and large light on-off ratio of 80, which is\nsuperior than 2D CDW TaS2 and most reported low-dimensional materials. The fact\nfor such high performance lies on two aspects. One is the much lower dark\ncurrent density resulted from the pseudo gap associated with 1D Luttinger\nliquid state, which is supported by finite size scaling of nonlinear I-V at\nvariable temperatures and occurrence of 1D structural phase transition\nconsolidated by In-situ Raman spectroscopy. The other is the high photocurrent\nassociated with the Frohlich superconductivity state, manifested by an\nultrasensitive switching, which can be only accessible in 1D CDW materials, in\nagreement with our density functional theory calculation. Our work thus reveals\nthe pivotal role of dimensionality in CDW phase transition, and paves a way for\nimplementing highly sensitive broadband photodetector.",
        "positive": "Biaxial tensile strain tuned up-and-down behavior on lattice thermal\n  conductivity in $\u03b2$-AsP monolayer: Various two-dimensional (2D) materials with graphene-like buckled structure\nemerge, and the $\\beta$-phase AsP monolayer has been recently proposed to be\nthermodynamically stable from first-principles calculations. The studies of\nthermal transport are very useful for these 2D materials-based nano-electronics\ndevices. Motivated by this, a comparative study of strain-dependent phonon\ntransport of AsP monolayer is performed by solving the linearized phonon\nBoltzmann equation within the single-mode relaxation time approximation (RTA).\nIt is found that the lattice thermal conductivity ($\\kappa_L$) of AsP monolayer\nis very close to one of As monolayer with similar buckled structure, which is\ndue to neutralization between the reduce of phonon lifetimes and group velocity\nenhancement from As to AsP monolayer. The corresponding room-temperature sheet\nthermal conductance of AsP monolayer is 152.5 $\\mathrm{W K^{-1}}$. It is noted\nthat the increasing tensile strain can harden long wavelength out-of-plane (ZA)\nacoustic mode, and soften the in-plane longitudinal acoustic (LA) and\ntransversal acoustic (TA) modes. Calculated results show that $\\kappa_L$ of AsP\nmonolayer presents a nonmonotonic up-and-down behavior with increased strain.\nThe unusual strain dependence is due to the competition among reduce of phonon\ngroup velocities, improved phonon lifetimes of ZA mode and nonmonotonic\nup-and-down phonon lifetimes of TA/LA mode. It is found that acoustic branches\ndominate the $\\kappa_L$ in considered strain range, and the contribution from\nZA branch increases with increased strain, while it is opposite for TA/LA\nbranch. By analyzing cumulative $\\kappa_L$ with respect to phonon mean free\npath (MFP), tensile strain can modulate effectively size effects on $\\kappa_L$\nin AsP monolayer."
    },
    {
        "anchor": "Molybdenum diselenide-manganese porphyrin bifunctional electrocatalyst\n  for hydrogen evolution reaction and selective hydrogen peroxide production: Electrochemical reactions for hydrogen and hydrogen peroxide production are\nessential for energy conversion to diminish energy crisis, but still lack\nefficient electrocatalysts. Development of non\\-noble metal bifunctional\nelectrocatalysts for hydrogen evolution and 2e oxygen reduction reaction to\nease reaction kinetics is a challenging task. Integration of single components\nby employing easy strategies provides a key\\-step towards the realization of\nhighly active electrocatalysts. In this vein, MoSe2 owns catalytic active sites\nand high specific surface area but suffers from insufficient conductivity and\nhigh catalytic performance that noble\\-metals provide. Herein, MoSe2 was used\nas a platform for the incorporation of manganese metallated porphyrin. The\ndeveloped hybrid, namely MoSe2\\-MnP, by the initial metal\\-ligand coordination\nand the subsequent grafting with MnP was fully characterized and\nelectrochemically assessed. The bifunctional electrocatalyst lowered the\noverpotential toward hydrogen evolution, improved reaction kinetics and charge\ntransfer processes and was extremely stable after 10000 ongoing cycles.\nSimultaneously, rotating ring disk electrode analysis showed that oxygen\nreduction proceeds through the 2e pathway for the selective production of\nhydrogen peroxide with a high yield of 97 percent. The new facile modification\nroute can be applied in diverse transition metal dichalcogenides and will help\nthe development of new advanced functional materials.",
        "positive": "Orbital currents in the Colle-Salvetti correlation energy functional and\n  the degeneracy problem: Popular density functionals for the exchange-correlation energy typically\nfail to reproduce the degeneracy of different ground states of open-shell\natoms. As a remedy, functionals which explicitly depend on the current density\nhave been suggested. We present an analysis of this problem by investigating\nfunctionals that explicitly depend on the Kohn-Sham orbitals. Going beyond the\nexact-exchange approximation by adding correlation in the form of the\nColle-Salvetti functional we show how current-dependent terms enter the\nColle-Salvetti expression and their relevance is evaluated. A very good\ndescription of the degeneracy of ground-states for atoms of the first and\nsecond row of the periodic table is obtained."
    },
    {
        "anchor": "Structural, Microstructural and Electrochemical Properties of Dispersed\n  Type Polymer Nanocomposite Films: The free standing solid polymer nanocomposite films has been prepared through\nstandard solution cast technique. The improvement in structural,\nmicrostructural and electrochemical properties has been observed on the\ndispersion of nanofiller in polymer salt complex. X Ray diffraction studies\nclearly reflect the formation of complex formation as no corresponding salt\npeak appeared in the diffractograms. The FTIR analysis suggested a clear and\nconvincing evidence of polymer ion, ion ion and polymer ion nanofiller\ninteraction. The highest ionic conductivity of the prepared solid polymer\nelectrolyte films is 5x10-5 S cm-1 for 7 wt. TiO2. The Linear Sweep Voltammetry\nprovide the electrochemical stability window of the prepared solid polymer\nelectrolyte films, which is of the order of 3.5 V. The ion transference number\nhas been estimated, tion is 0.99 through dc polarization technique. Dielectric\nspectroscopic studies were performed to understand the ion transport process in\npolymer electrolytes. All solid polymer electrolyte possesses good thermal\nstability up to 300C. DSC analysis confirms the decrease of melting temperature\nand signal of glass transition temperature with addition of nanofiller which\nindicates the decrease of crystallinity of polymer matrix. An absolute\ncorrelation between diffusion coefficient, ion mobility, number density, double\nlayer capacitance, glass transition temperature, melting temperature, free ion\narea and conductivity has been observed. A convincing model to study the role\nof nanofiller in polymer salt complex has been proposed which supports the\nexperimental findings. The prepared polymer electrolyte system with significant\nionic conductivity, high ionic transference number, good thermal, voltage\nstability could be suggested as a potential candidate as electrolyte cum\nseparator for fabrication of rechargeable lithium-ion battery system.",
        "positive": "Quantitative Temperature Dependence of Longitudinal Spin Seebeck Effect\n  at High Temperatures: This article reports temperature-dependent measurements of longitudinal spin\nSeebeck effects (LSSEs) in Pt/Y$_3$Fe$_5$O$_{12}$ (YIG)/Pt systems in a high\ntemperature range from room temperature to above the Curie temperature of YIG.\nThe experimental results show that the magnitude of the LSSE voltage in the\nPt/YIG/Pt systems rapidly decreases with increasing the temperature and\ndisappears above the Curie temperature. The critical exponent of the LSSE\nvoltage in the Pt/YIG/Pt systems at the Curie temperature was estimated to be\n3, which is much greater than that for the magnetization curve of YIG. This\ndifference highlights the fact that the mechanism of the LSSE cannot be\nexplained in terms of simple static magnetic properties in YIG."
    },
    {
        "anchor": "Temperature dependence of Raman-active optical phonons in Bi_2Se_3 and\n  Sb_2Te_3: Inelastic light scattering spectra of Bi_2Se_3 and Sb_2Te_3 single crystals\nhave been measured over the temperature range from 5 K to 300 K. The\ntemperature dependence of dominant A^{2}_{1g} phonons shows similar behavior in\nboth materials. The temperature dependence of the peak position and linewidth\nis analyzed considering the anharmonic decay of optical phonons and the\nmaterial thermal expansion. This work suggests that Raman spectroscopy can be\nused for thermometry in Bi_2Se_3- and Sb_2Te_3-based devices in a wide\ntemperature range.",
        "positive": "Effect of molecular structure and oxidation potential on the device\n  performance of single-carrier organic diodes: The fabrication of single-carrier organic diodes from a series of sixteen\nmolecular materials is reported. We experimentally demonstrate how the\nmolecular structure affects the film morphology, and how the film morphology\ninfluences the diode performance. The compounds, with moderate molecular size\nand dendritic structures, are shown to be more favorable for good device\nperformance than those small molecules with symmetry structures. The device\nturn-on voltage is found to be strongly dependent on the molecular first\noxidation potentials. Independent of different anode materials, no obvious\ninterfacial charge/dipole effects are observed in the devices. Our results may\nsuggest that singlecarrier organic diode might offer a simple way for screeing\nappropriate molecular materials preferable for practical multilayer devices."
    },
    {
        "anchor": "Observation and origin of the $\u0394$-manifold in Si:P $\u03b4$-layers: By creating a sharp and dense dopant profile of phosphorus atoms buried\nwithin a silicon host, a two-dimensional electron gas is formed within the\ndopant region. Quantum confinement effects induced by reducing the thickness of\nthe dopant layer, from $4.0$\\,nm to the single-layer limit, are explored using\nangle-resolved photoemission spectroscopy. The location of theoretically\npredicted, but experimentally hitherto unobserved, quantum well states known as\nthe $\\Delta$-manifold is revealed. Moreover, the number of carriers hosted\nwithin the $\\Delta$-manifold is shown to be strongly affected by the\nconfinement potential, opening the possibility to select carrier\ncharacteristics by tuning the dopant-layer thickness.",
        "positive": "Towards understanding of magnetization reversal in Nd$-$Fe$-$B\n  nanocomposites: Analysis by high-throughput micromagnetic simulations: We demonstrate how micromagnetic simulations can be employed in order to\ncharacterize and analyze the magnetic microstructure of nanocomposites. For the\nexample of nanocrystalline Nd$-$Fe$-$B, which is a potential material for\nfuture permanent-magnet applications, we have compared three different models\nfor the micromagnetic analysis of this material class: (i) a description of the\nnanocomposite microstructure in terms of Stoner-Wohlfarth particles with and\nwithout the magnetodipolar interaction; (ii) a model based on the core-shell\nrepresentation of the nanograins; (iii) the latter model including a\ncontribution of superparamagnetic clusters. The relevant parameter spaces have\nbeen systematically scanned with the aim to establish which micromagnetic\napproach can most adequately describe experimental data for this material.\nAccording to our results, only the last, most sophisticated model is able to\nprovide an excellent agreement with the measured hysteresis loop. The presented\nmethodology is generally applicable to multiphase magnetic nanocomposites and\nit highligths the complex interrelationship between the microstructure,\nmagnetic interactions, and the macroscopic magnetic properties."
    },
    {
        "anchor": "Control of magnetization reversal in oriented Strontium Ferrite thin\n  films: Oriented Strontium Ferrite films with the c axis orientation were deposited\nwith varying oxygen partial pressure on Al2O3(0001) substrate using PLD\ntechnique. The angle dependent magnetic hysteresis, remanent coercivity and\ntemperature dependent coercivity had been employed to understand the\nmagnetization reversal of these films. It was found that the Strontium Ferrite\nthin film grown at lower (higher) oxygen partial pressure shows\nStoner-Wohlfarth type (Kondorsky like) reversal. The relative importance of\npinning and nucleation processes during magnetization reversal is used to\nexplain the type of the magnetization reversal with different oxygen partial\npressure during growth.",
        "positive": "A machine learning approach to predict L-edge x-ray absorption spectra\n  of light transition metal ion compounds: Simulation of spectra of x-ray absorption spectroscopy (XAS) at the L-edge is\na well-established and reliable computational tool that, in combination with\nexperimental measurements, reveals details about the local electronic structure\nand the chemical environment of transition metal ions (TMI). For light TMIs,\nmodel 2p XAS model Hamiltonian approaches (MHA) are fast and accurate in\ncomputing spectra. Here, an alternative method using artificial neural networks\n(ANN) is employed. The new approach predicts x-ray absorption spectra at the\nL-edge of light transition metals ions for elements from Ti to Ni, including\ndifferent oxidation states, from sets of physical input parameters.\nComputational performance and accuracy were optimized through a systematic\nexploration of ANN design and compared to MHA simulations. While the MHA\nremains more accurate due to the statistical nature of the developed machine\nlearning method, the ANN-based prediction of 2p XAS spectra achieved good\naccuracy of more than 99%, in addition to a noticeable advantage in\ncomputational speed. This makes the method intrinsically more suitable for\ncomputational high-throughput setups as well as in support of data-intense\nexperimental workflows. However, the extrapolation weakness of artificial\nneural networks remained for most cases and displayed a strong dependence on\nthe TMI. For one TMI, an extrapolation accuracy of 78% was maintained."
    },
    {
        "anchor": "Antiferroelectric instability in kagome francisites\n  Cu$_3$Bi(SeO$_3$)$_2$O$_2$X (X = Cl, Br): Density-functional calculations of lattice dynamics and high-resolution\nsynchrotron powder diffraction uncover antiferroelectric distortion in the\nkagome francisite Cu$_3$Bi(SeO$_3$)$_2$O$_2$Cl below 115K. Its Br-containing\nanalogue is stable in the room-temperature crystal structure down to at least\n10K, although the Br compound is on the verge of a similar antiferroelectric\ninstability and reveals local displacements of Cu and Br atoms. The\nI-containing compound is stable in its room-temperature structure according to\ndensity-functional calculations. We show that the distortion involves\ncooperative displacements of Cu and Cl atoms, and originates from the\noptimization of interatomic distances for weakly bonded halogen atoms. The\ndistortion introduces a tangible deformation of the kagome spin lattice and may\nbe responsible for the reduced net magnetization of the Cl compound compared to\nthe Br one. The polar structure of Cu$_3$Bi(SeO$_3$)$_2$O$_2$Cl is only\nslightly higher in energy than the non-polar antiferroelectric structure, but\nno convincing evidence of its formation could be obtained.",
        "positive": "FIB synthesis of Bi2Se3 1D nanowires demonstrating the co-existence of\n  Shubnikov-de Haas oscillations and linear magnetoresistance: Since the discovery of topological insulators (TI), there are considerable\ninterests in demonstrating metallic surface states, their shielded robust\nnature to the backscattering and study their properties at nanoscale dimensions\nby fabricating nanodevices. Here we address an important scientific issue\nrelated to TI whether one can clearly demonstrate the robustness of topological\nsurface states (TSS) to the presence of disorder that does not break any\nfundamental symmetry. The simple straightforward method of FIB milling was used\nto synthesize nanowires of Bi2Se3 which we believe an interesting route to test\nrobustness of TSS and obtained results are new compared to many of the earlier\npapers on quantum transport in TI demonstrating robustness of metallic SS to\ngallium doping. In presence of perpendicular magnetic field, we have observed\nthe co-existence of Shubnikov de Haas oscillations and linear magnetoresistance\nwhich was systematically investigated at different channel lengths indicating\nthe Dirac dispersive surface states. The transport properties and estimated\nphysical parameters shown here demonstrate the robustness of SS to the\nfabrication tools triggering flexibility to explore new exotic quantum\nphenomena at nanodevice level."
    },
    {
        "anchor": "Robust optical conductivity in gapped graphene: We study the optical conductivity in the low-energy regime of gapped mono-\nand bilayer graphene. A scaling relation is found, in which the four parameters\nfrequency, gap, Fermi energy and temperature appear only as combination of\nthree independent parameters. The ratio of the optical conductivity of bilayer\nand mononlayer graphene is exactly 2.",
        "positive": "Mechanochemical reaction in graphane under uniaxial tension: The quantum-mechanochemical-reaction-coordinate simulations have been\nperformed to investigate the mechanical properties of hydrogen functionalized\ngraphene. The simulations disclosed atomically matched peculiarities that\naccompany the deformation-failure-rupture process occurred in the body. A\ncomparative study of the deformation peculiarities related to equi-carbon-core\n(5,5) nanographene and nanographane sheets exhibited a high stiffness of both\nbodies that is provided by the related hexagon units, namely benzenoid and\ncyclohexanoid, respectively. The two units are characterized by anisotropy in\nthe microscopic behavior under elongation along mechanochemical internal\ncoordinates when the later are oriented either along (zg) or normally (ach) to\nthe C-C bonds chain. The unit feature in combination with different\nconfiguration of their packing with respect to the body C-C bond chains forms\nthe ground for the structure-sensitive mechanical behavior that is different\nfor zg and ach deformation modes. Hydrogenation of graphene drastically\ninfluences behavior and numerical characteristics of the body making\ntricotage-like pattern of the graphene failure less pronounced and inverting it\nfrom the zg to ach mode as well as providing less mechanical resistance of\ngraphane it total."
    },
    {
        "anchor": "Thickness dependent mechanical properties of soft ferromagnetic\n  two-dimensional CoTe2: Two dimensional (2D) layered transition-metal-based tellurides (chalcogens)\nare known to harness their surface atoms characteristics to enhance\ntopographical activities for energy conversion, storage, and magnetic\napplications. High surface energy due to unsaturated dangling bonds and larger\nlateral size than the thickness (volume) makes them a potential candidate for\nemerging electronics. Nevertheless, the gradual stacking of each sheet alters\nthe surface atoms' subtle features, such as lattice expansion, leading to\nseveral phenomena and rendering tunable properties. In the present work, we\nhave monitored thickness-dependent properties of the 2D CoTe2 sheets from\nnanoscale mechanics, tribology, surface potential distributions, interfacial\ninteraction and magnetism using atomically resolved spectroscopy and different\nsurface probe techniques, in conjunction with theoretical investigations:\ndensity functional theory (DFT) and molecular dynamics (MD). The variation in\nproperties observed in theoretical investigation unleashes the crucial role of\ncrystal planes of the CoTe2. The presented results are beneficial in expanding\nthe use of 2D telluride family in flexible electronics, piezo sensors,\ntribo-generator, and next-generation memory devices.",
        "positive": "Surface energies, work functions, and surface relaxations of low index\n  metallic surfaces from first-principles: We study the relaxations, surface energies, and work functions of low index\nmetallic surfaces using pseudopotential plane-wave density-functional\ncalculations within the generalized gradient approximation. We study here the\n(100), (110), and (111) surfaces of Al, Pd, Pt, and Au and the (0001) surface\nof Ti, chosen for their use as contact or lead materials in nanoscale devices.\nWe consider clean, mostly non-reconstructed surfaces in the slab-supercell\napproximation. Particular attention is paid to the convergence of these\nquantities with respect to slab thickness; furthermore, different methodologies\nfor the calculation of work functions and surfaces energies are compared. We\nfind that the use of bulk references for calculations of surface energies and\nwork functions can be detrimental to convergence unless numerical grids are\nclosely matched, especially when surface relaxations are being considered. Our\nresults and comparison show that calculated values often do not quantitatively\nmatch experimental values. This may be understandable for the surface\nrelaxations and surface energies, where experimental values can have large\nerror, but even for the work functions, neither local nor semi-local\nfunctionals emerge as an accurate choice for every case."
    },
    {
        "anchor": "First principles investigation of high thermal conductivity in hexagonal\n  germanium carbide(2H-GeC): Designing and searching for a high thermal conductivity material in both bulk\nand nanoscale is highly demanding for electronics cooling. In this work, we\nstudied the thermal conductivity of 2H-Germanium Carbide(2H-GeC) using first\nprinciples calculations. At 300 K, we are reporting a high thermal conductivity\nof 1350 Wm-1K-1 and 1050 Wm-1K-1 along a-axis and c-axis respectively for pure\n2H-GeC. These values are 130% higher than the thermal conductivity of\n2H-silicon carbide and 20% lower than cubic germanium carbide(c-GeC). We\nanalyzed the phonon group velocities, phonon scattering rates and mode\ncontribution from acoustic and optical phonons. We also studied the thermal\nconductivity of nanostructured 2H-GeC for heat dissipation in nanoelectronics.\nAt room temperature, thermal conductivity of 2H-GeC is ~65 Wm-1K-1 at nanometer\nlength scales(L) of 100 nm is equal to that of the c-GeC. This result suggests\nthat, 2H- GeC will be a promising material for thermal management applications\nin micro/nano electronics.",
        "positive": "Fast fourier transform and multi-Gaussian fitting of XRR data to\n  determine the thickness of ALD grown thin films within the initial growth\n  regime: While a linear growth behavior is one of the fingerprints of textbook atomic\nlayer deposition processes, the growth often deviates from that behavior in the\ninitial regime, i.e. the first few cycles of a process. To properly understand\nthe growth behavior in the initial regime is particularly important for\napplications that rely on the exact thickness of very thin films. The\ndetermination of the thicknesses of the initial regime, however, often requires\nspecial equipment and techniques that are not always available. We propose a\nthickness determination method that is based on X-ray reflectivity (XRR)\nmeasurements on double layer structures, i.e. substrate/base layer/top layer.\nXRR is a standard thin film characterization method. Utilizing the inherent\nproperties of fast Fourier transformation in combination with a multi-Gaussian\nfitting routine permits the determination of thicknesses down to $t \\approx 2$\nnm. We evaluate the boundaries of our model, which are given by the separation\nand full width at half maximum of the individual Gaussians. Finally, we compare\nour results from two layer stacks with data from X-ray fluorescence\nspectroscopy, which is a standard method for measuring ultra thin films."
    },
    {
        "anchor": "On automatic determination of quasicrystal orientations by indexing of\n  detected reflections: Automatic crystal orientation determination and orientation mapping are\nimportant tools for research on polycrystalline materials. The most common\nmethods of automatic orientation determination rely on detecting and indexing\nindividual diffraction reflections. These methods, however, have not been used\nfor orientation mapping of quasicrystalline materials. The paper describes\nnecessary changes to existing software designed for orientation determination\nof periodic crystals so that it can be applied to quasicrystals. The changes\nare implemented in one of such programs. The functioning of the modified\nprogram is illustrated by an example orientation map of an icosahedral\npolycrystal.",
        "positive": "Sink strength calculations of dislocations and loops using OKMC: We calculate the sink strength of dislocations and toroidal absorbers using\nObject Kinetic Monte Carlo and compare with the theoretical expressions. We get\ngood agreement for dislocations and loop-shaped absorbers of 3D migrating\ndefects, provided that the volume fraction is low, and fair agreements for\ndislocations with 1D migrating defects. The master curve for the 3D to 1D\ntransition is well reproduced with loop-shaped absorbers and fairly well with\ndislocations. We conclude that, on the one hand, the master curve is correct\nfor a wide range of sinks and that, on the other, OKMC techniques inherently\ntake correctly into account the strengths of sinks of any shape, provided that\nan effective way of appropriately inserting the sinks to be studied can be\nfound."
    },
    {
        "anchor": "Virtual spectrometer for stable radicals vibrations. 2. Graphene\n  molecules: The article presents the result of an extended in silico experiment on\ncomputational vibrational spectroscopy of graphene molecules performed using\nthe virtual vibrational spectrometer UHF VVS, previously proposed in the first\npart of the study [1]. Since in vitro spectroscopy of such individual molecules\nis practically impossible, the obtained spectra give the first idea of what\nthese spectra could be. A large set of studied molecules allows drawing the\nfirst conclusions about the specific features of the vibrational dynamics of\nthe substances, caused by their radical structure and spin features of the\nground electronic state.",
        "positive": "Correlating Chemical Reaction and Mass Transport in Hydrogen-based\n  Direct Reduction of Iron Oxide: Steelmaking contributes 8% to the total CO2 emissions globally, primarily due\nto coal-based iron ore reduction. Clean hydrogen-based ironmaking has variable\nperformance because the dominant gas-solid reduction mechanism is set by the\ndefects and pores inside the mm-nm sized oxide particles that change\nsignificantly as the reaction progresses. While these governing dynamics are\nessential to establish continuous flow of iron and its ores through reactors,\nthe direct link between agglomeration and chemistry is still contested due to\nmissing measurements. In this work, we directly measure the connection between\nchemistry and agglomeration in the smallest iron oxides relevant to magnetite\nores. Using synthesized spherical 10-nm magnetite particles reacting in H2, we\nresolve the formation and consumption of w\\\"ustite (FeO) - the step most\ncommonly attributed to agglomeration. Using X-ray scattering and microscopy, we\nresolve crystallographic anisotropy in the rate of the initial reaction, which\nbecomes isotropic as the material sinters. Complementing with imaging, we\ndemonstrate how the particles self-assemble, subsequently react and sinter into\n~100x oblong grains. Our insights into how morphologically uniform iron oxide\nparticles react and agglomerate H2 reduction enable future size-dependent\nmodels to effectively describe the multiscale iron ore reduction."
    },
    {
        "anchor": "Gate-controlled photo-oxidation of graphene for electronic structure\n  modification: Graphene is an ultrathin material, which allows us to control surface\nphenomena by means of field-effect gating. Among various surface phenomena,\nphoto-oxidation is known to be a facile method to largely control the\nelectronic structure of graphene. In this study, gate controllability of\nphoto-oxidation of graphene is thoroughly examined using a\nfield-effect-transistor configuration. The presence of water molecules enhances\ngate controllability, which can be explained using water-oxygen co-adsorption\npicture. In addition, the photo-oxidation reaction evolves from the edge and\nproceeds towards the center of the graphene channel, which can be understood by\nthe fringing field effect. Semiconducting characteristics are successfully\nobtained by narrowing of the graphene channel, suggesting possible formation of\na graphene nanoribbon under mild conditions, i.e., in air at room temperature.",
        "positive": "Scaling like behaviour of resistivity observed in LaNiO_3 thin films\n  grown on SrTiO_3 substrate by pulsed laser deposition: We discuss the origin of the temperature dependence of resistivity observed\nin highly oriented LaNiO_3 thin films (of thickness d) grown on SrTiO_3\nsubstrate by a pulsed laser deposition technique. All the experimental data are\nfound to collapse into a single universal curve [T/T_{sf}(d)]^{3/2} for the\nentire temperature interval (20K<T<300K) with T_{sf}(d) being the onset\ntemperature for triggering a resonant scattering of conduction electrons by\nspin fluctuations in LaNiO_3/SrTiO_3 heterostructure."
    },
    {
        "anchor": "Adsorption of Helium atoms on two-dimensional substrates: The study of the adsorption phenomenon of helium began many decades ago with\nthe discovery of graphite as a homogeneous substrate for investigation of\nphysically adsorbed monolayer films. In particular, helium monoatomic layers on\ngraphite were found to exhibit a very rich phase diagram.\n  In the present work we have investigated the adsorption phenomenon of helium\natoms on graphene and silicene substrates by means of density functional theory\nwith Born-Oppenheimer approximation. Helium-substrate and helium-helium\ninteractions were considered from first principles. Vibrational properties of\nadsorbed monolayers have been used to explore the stability of the system. This\napproach reproduces results describing the stability of a helium monolayer on\ngraphene calculated by quantum Monte Carlo (QMC) simulations for low and high\ncoverage cases. However, for the moderate coverage value there is discrepancy\nwith QMC results due to the lack of helium zero point motion.",
        "positive": "Electron energy loss in carbon nanostructures: The response of fullerenes and carbon nanotubes is investigated by\nrepresenting each carbon atom by its atomic polarizability. The polarization of\neach carbon atom produces an induced dipole that is the result of the\ninteraction with a given external field plus the mutual interaction among\ncarbon atoms. The polarizability is obtained from the dielectric function of\ngraphite after invoking the Clausius-Mossotti relation. This formalism is\napplied to the simulation of electron energy loss spectra both in fullerenes\nand in carbon nanotubes. The case of broad electron beams is considered and the\nloss probability is analyzed in detail as a function of the electron deflection\nangle within a fully quantum-mechanical description of the electrons. A general\ngood agreement with available experiments is obtained in a wide range of probe\nenergies between 1 keV and 60 keV."
    },
    {
        "anchor": "Electronic Structure of Amorphous Copper Iodide: A p-type Transparent\n  Semiconductor: The atomic and electronic structure of the p-type transparent amorphous\nsemiconductor CuI is calculated by ab-initio molecular dynamics. It is found to\nconsist of a random tetrahedrally bonded network. The hole effective mass is\nfound to be quite low, as in the crystal. The valence band maximum (VBM) state\nhas a mixed I(p)-Cu(t2g)-I(p) character, and its energy is relatively\ninsensitive to disorder. An iodine excess creates holes that move the Fermi\nlevel into the valence band, but it does not pin the Fermi level above the VBM\nmobility edge. Thus the Fermi level can easily enter the valence band if\np-doped, similar to the behavior of electrons in In-Ga-Zn oxide semiconductors\nbut opposite to that of electrons in a-Si:H. This suggests that amorphous CuI\ncould make an effective p-type transparent semiconductor.",
        "positive": "Bilayer stanene on a magnetic topological insulator: A two-dimensional superconducting adlayer grown on a magnetic topological\ninsulator (MTI) has the potential to exhibit proximity induced\nsuperconductivity, facilitate the existence of Majorana fermions and find\napplications in the field of quantum computing. In this work, we demonstrate\nthe formation of bilayer stanene on an MTI substrate, specifically\nMn(Bi$_{0.74}$Sb$_{0.26}$)$_2$Te$_4$ (MBST), through utilization of a\ncombination of techniques such as angle-resolved photoemission spectroscopy\n(ARPES), scanning tunneling microscopy (STM), density functional theory (DFT),\nx-ray photoelectron spectroscopy (XPS), and low energy electron diffraction\n(LEED). The stanene related bands observed in ARPES have been corroborated by\nour DFT calculations. Atomic resolution STM topography images confirm the\nformation of monolayer as well as bilayer stanene. A buffer layer -- formed due\nto chemical bonding of Sn with the upper two layers of MBST (Te and Bi/Sb) --\nfacilitates the growth of stanene."
    },
    {
        "anchor": "Glassy nature of Ce65Al25Co10 alloy: A metallic glass: In the present investigation the glass forming ability of Ce65Al25Co10\nmetallic glass has been reported. It was successfully synthesised using melt\nspinning techniques. The existence of amorphous phase in Ce65Al25Co10 alloy\nhave been proved using X-ray diffraction (XRD) and transmission electron\nmicroscopy (TEM) measurements. The thermal analysis of the synthesised sample\nusing differential scanning calorimetry (DSC) shows a glass transition around\n371 K, thus confirms existence of glassy phase at room temperature. The\nhardness of the synthesised sample at different load have been demonstrated.\nMoreover, the yield strength of the synthesised sample has also been calculated\nby means of hardness data and Meyer exponent.",
        "positive": "NMR study of AgInTe$_2$ at normal and high pressure: The ternary semiconductor AgInTe$_2$ is a thermoelectric material with\nchalcopyrite-type structure that transforms reversibly into a rocksalt-type\nstructure under high pressure. Nuclear magnetic resonance (NMR) is considered\nto provide unique insight into material properties on interatomic length\nscales, especially in the context of structural phase transitions. Here,\n$^{115}$In and $^{125}$Te NMR is used to study AgInTe$_2$ for ambient\nconditions and pressures up to 5 GPa. Magnetic field dependent and magic angle\nspinning (MAS) experiments of $^{125}$Te prove strongly enhanced internuclear\ncouplings, as well as a distribution of isotropic chemical shifts suggesting a\ncertain degree of cation disorder. The indirect nuclear coupling is smaller for\n$^{115}$In, as well as the chemical shift distribution in agreement with the\ncrystal structure. The $^{115}$In NMR is further governed by a small\nquadrupolar interaction ($\\nu_\\mathrm{Q} \\approx$ 90 kHz) and shows an orders\nof magnitude faster nuclear relaxation in comparison to that of $^{125}$Te. At\na pressure of about 3 GPa, the $^{115}$In quadrupole interaction increases\nsharply to about 2400 kHz, indicating a phase transition to a structure with a\nwell defined, though non-cubic local symmetry, while the $^{115}$In shift\nsuggests no significant changes of the electronic structure. The NMR signal is\nlost above about 5 GPa (at least up to about 10 GPa). However, upon releasing\nthe pressure a signal is recovered that points to the reported metastable\nambient pressure phase with a high degree of disorder."
    },
    {
        "anchor": "First principles theoretical studies of half-metallic ferromagnetism in\n  CrTe: Using full-potential linear augmented plane wave method (FP-LAPW) and the\ndensity functional theory, we have carried out a systematic investigation of\nthe electronic, magnetic, and cohesive properties of the chalcogenide CrTe in\nthree competing structures: rock-salt (RS), zinc blende (ZB) and the NiAs-type\n(NA) hexagonal. Although the ground state is of NA structure, RS and ZB are\ninteresting in that these fcc-based structures, which can possibly be grown on\nmany semiconductor substrates, exhibit half-metallic phases above some critical\nvalues of the lattice parameter. We find that the NA structure is not\nhalf-metallic at its equilibrium volume, while both ZB and RS structures are.\nThe RS structure is more stable than the ZB, with an energy that is lower by\n0.25 eV/atom. While confirming previous results on the half-metallic phase in\nZB structure, we provide hitherto unreported results on the half-metallic RS\nphase, with a gap in the minority channel and a magnetic moment of 4.0\n$\\mu_{B}$ per formula unit. A comparison of total energies for the\nferromagnetic (FM), non-magnetic (NM), and antiferromagnetic (AFM)\nconfigurations shows the lowest energy configuration to be FM for CrTe in all\nthe three structures. The FP-LAPW calculations are supplemented by linear\nmuffin-tin orbital (LMTO) calculations using both local density approximation\n(LDA) and LDA+U method. The exchange interactions and the Curie temperatures\ncalculated via the linear response method in ZB and RS CrTe are compared over a\nwide range of the lattice parameter. The calculated Curie temperatures for the\nRS phase are consistently higher than those for the ZB phase.",
        "positive": "On the physisorption of water on graphene: a CCSD(T) study: The electronic structure of the zero-gap two-dimensional graphene has a\ncharge neutrality point exactly at the Fermi level that limits the practical\napplication of this material. There are several ways to modify the\nFermi-level-region of graphene, e.g. adsorption of graphene on different\nsubstrates or different molecules on its surface. In all cases the so-called\ndispersion or van der Waals interactions can play a crucial role in the\nmechanism, which describes the modification of electronic structure of\ngraphene. The adsorption of water on graphene is not very accurately reproduced\nin the standard density functional theory (DFT) calculations and\nhighly-accurate quantum-chemical treatments are required. A possibility to\napply wavefunction-based methods to extended systems is the use of local\ncorrelation schemes. The adsorption energies obtained in the present work by\nmeans of CCSD(T) are much higher in magnitude than the values calculated with\nstandard DFT functional although they agree that physisorption is observed. The\nobtained results are compared with the values available in literature for\nbinding of water on the graphene-like substrates."
    },
    {
        "anchor": "Designing graphene/hexagonal boron nitride superlattice monolayer with\n  high thermoelectric performance: We design a hybrid graphene/hexagonal boron nitride superlattice monolayer\nand investigate its thermoelectric properties using density functional theory\nand Boltzmann transport equations with the relaxation time accurately treated\nby electron-phonon coupling calculations. Compared with that of pristine\ngraphene, the lattice thermal conductivity of the superlattice structure is\nmore than two orders of magnitude lower due to the enhanced three-phonon\nscattering process originated from the mixed-bond characteristics. Besides, the\ncoexistence of light and heavy bands around the Fermi level leads to an\nultrahigh power factor along the zigzag direction, where the highest ZT value\nof ~2.5 can be achieved for the n-type system at 1100 K. Moreover, it is noted\nthat the carrier transport near the valance band minimum is almost entirely\ncontributed by the graphene part of the superlattice. As a consequence, the\nthermoelectric performance of p-type system can be enhanced to be comparable\nwith that of n-type one by appropriate substitution of nitrogen atom with\nphosphorus, which can suppress the lattice thermal conductivity but nearly have\nno influence on the hole transport.",
        "positive": "Boron doping in gallium oxide from first principles: We study the feasibility of boron doping in gallium oxide\n($\\text{Ga}_2\\text{O}_3$) for neutron detection. $\\text{Ga}_2\\text{O}_3$ is a\nwide band-gap, radiation hard material which has potential for neutron\ndetection if it can be doped with a neutron active element. We investigate the\nboron-10 isotope as a possible neutron active dopant. Intrinsic and boron\ninduced defects in $\\text{Ga}_2\\text{O}_3$ are studied with semi-local and\nhybrid density-functional-theory calculations. We find that in growth\nconditions favourable for boron, boron substitutional defects are likely to\nform making boron doping of $\\text{Ga}_2\\text{O}_3$ feasible."
    },
    {
        "anchor": "Pentagonal Monolayer Crystals of Carbon, Boron Nitride, and Silver Azide: In this study we present a theoretical investigation of structural,\nelectronic and mechanical properties of pentagonal monolayers of carbon\n(p-graphene), boron nitride (p-B$_{2}$N$_{4}$ and p-B$_{4}$N$_{2}$) and silver\nazide (p-AgN$_{3}$) by performing state-of-the-art first principles\ncalculations. Our total energy calculations suggest feasible formation of\nmonolayer crystal structures composed entirely of pentagons. In addition,\nelectronic band dispersion calculations indicate that while p-graphene and\np-AgN$_{3}$ are semiconductors with indirect bandgaps, p-BN structures display\nmetallic behavior. We also investigate the mechanical properties (in-plane\nstiffness and the Poisson's ratio) of four different pentagonal structures\nunder uniaxial strain. p-graphene is found to have the highest stiffness value\nand the corresponding Poisson's ratio is found to be negative. Similarly,\np-B$_{2}$N$_{4}$ and p-B$_{4}$N$_{2}$ have negative Poisson's ratio values. On\nthe other hand, the p-AgN$_{3}$ has a large and positive Poisson's ratio. In\ndynamical stability tests based on calculated phonon spectra of these\npentagonal monolayers, we find that only p-graphene and p-B$_{2}$N$_{4}$ are\nstable, but p-AgN$_{3}$ and p-B$_{4}$N$_{2}$ are vulnerable against vibrational\nexcitations.",
        "positive": "Cumulative Polarization Coexisting with Conductivity at Interfacial\n  Ferroelectrics: Ferroelectricity in atomically thin bilayer structures has been recently\npredicted1 and measured[2-4] in two-dimensional (2D) materials with hexagonal\nnon-centrosymmetric unit-cells. Interestingly, the crystal symmetry translates\nlateral shifts between parallel 2D layers to a change of sign in their\nout-of-plane electric polarization, a mechanism referred to as\n\"Slide-Tronics\"[4]. These observations, however, have been restricted to\nswitching between only two polarization states under low charge carrier\ndensities[5-12], strongly limiting the practical application of the revealed\nphenomena[13]. To overcome these issues, one needs to explore the nature of the\npolarization that arises in multi-layered van der Waals (vdW) stacks, how it is\ngoverned by intra- and inter-layer charge redistribution, and to which extent\nit survives the introduction of mobile charge carriers, all of which are\npresently unknown14. To explore these questions, we conduct surface potential\nmeasurements of parallel WSe2 and MoS2 multi-layers with aligned and\nanti-aligned configurations of the polar interfaces. We find evenly spaced,\nnearly decoupled potential steps, indicating highly confined interfacial\nelectric fields, which provide means to design multi-state \"ladder\nferroelectrics\". Furthermore, we find that the internal polarization remains\nsignificant upon electrostatic doping of a mobile charge carrier density as\nhigh as 1013 cm-2, with substantial in-plane conductivity. Using\nfirst-principles calculations based on density functional theory (DFT), we\ntrace the extra charge redistribution in real and momentum space and identify\nan eventual doping-induced depolarization mechanism."
    },
    {
        "anchor": "Plasma-enhanced atomic layer deposition of Al$_2$O$_3$ on graphene using\n  monolayer hBN as interfacial layer: The deposition of dielectric materials on graphene is one of the bottlenecks\nfor unlocking the potential of graphene in electronic applications. In this\npaper we demonstrate the plasma enhanced atomic layer deposition of 10 nm thin\nhigh quality Al$_2$O$_3$ on graphene using a monolayer of hBN as protection\nlayer. Raman spectroscopy was performed to analyze possible structural changes\nof the graphene lattice caused by the plasma deposition. The results show that\na monolayer of hBN in combination with an optimized deposition process can\neffectively protect graphene from damage, while significant damage was observed\nwithout an hBN layer. Electrical characterization of double gated graphene\nfield effect devices confirms that the graphene did not degrade during the\nplasma deposition of Al$_2$O$_3$. The leakage current densities were\nconsistently below 1 nA/mm for electric fields across the insulators of up to 8\nMV/cm, with irreversible breakdown happening above. Such breakdown electric\nfields are typical for Al$_2$O$_3$ and can be seen as an indicator for high\nquality dielectric films.",
        "positive": "Equation of state of paramagnetic CrN from ab initio molecular dynamics: Equation of state for chromium nitride has been debated in the literature in\nconnection with a proposed collapse of its bulk modulus following the pressure\ninduced transition from the paramagnetic cubic phase to the antiferromagnetic\northorhombic phase [F. Rivadulla et al., Nat Mater 8, 974 (2009); B. Alling et\nal., Nat Mater 9, 283 (2010)]. Experimentally the measurements are complicated\ndue to the low transition pressure, while theoretically the simulation of\nmagnetic disorder represent a major challenge. Here a first-principles method\nis suggested for the calculation of thermodynamic properties of magnetic\nmaterials in their high temperature paramagnetic phase. It is based on\nab-initio molecular dynamics and simultaneous redistributions of the disordered\nbut finite local magnetic moments. We apply this disordered local moments\nmolecular dynamics method to the case of CrN and simulate its equation of\nstate. In particular the debated bulk modulus is calculated in the paramagnetic\ncubic phase and is shown to be very similar to that of the antiferromagnetic\northorhombic CrN phase for all considered temperatures."
    },
    {
        "anchor": "Novel wide spectrum light absorber heterostructures based on\n  hBN/In(Ga)Te: Two-dimensional group III monochalcogenides have recently attracted quite\nattention for their wide spectrum of optical and electric properties, being\npromising candidates for optoelectronic and novel electrical applications,\nhowever in their pristine form they are very sensitive and vulnerable to oxygen\nin air. Here we present two newly designed vdW heterostructures based on hBN\n(hexagonal boron nitride) and GaTe or InTe monolayer. Using density functional\ntheory we investigate electronic and optical properties of those structures.\nTheir moderate band gap and an good absorption coefficient makes them excellent\nfor absorbers in wide spectrum, covering all from part of IR to far UV\nspectrum, with particularly good absorption of UV light. The hBN layer which\ncan be beneficial for protection of sensitive GaTe and InTe does not only\npreserve their optical properties but also enhances it. Moreover, we confirm\nthat type of stacking does not affect any relevant properties, as all three\nstacking types are very similar in total energy and bandstructure is almost the\nsame for every one. This is especially important for easier experimental\nrealization.",
        "positive": "Nondestructive femtosecond laser lithography of Ni nanocavities by\n  controlled thermo-mechanical spallation at the nanoscale: We present a new approach to femtosecond direct laser writing lithography to\npattern nanocavities in ferromagnetic thin films. To demonstrate the concept we\nirradiated 300~nm thin nickel films by single intense femtosecond laser pulses\nthrough the glass substrate and created complex surface landscapes at the\nnickel-air interface. Using a fluence above the ablation threshold the process\nis destructive and irradiation leads to the formation of 200~nm thin flakes of\nnickel around the ablation crater as seen by electron microscopy. By\nprogressively lowering the peak laser fluence, slightly below the ablation\nthreshold the formation of closed spallation cavities is demonstrated by\ninterferometric microscopy. Systematic studies by electron and optical\ninterferometric microscopies enabled us to gain an understanding of the\nthermo-mechanical mechanism leading to spallation at the solid-molten\ninterface, a conclusion supported by molecular dynamics simulations. We\nachieved a control of the spallation process that enabled the fabrication of\nclosed spallation nanocavities and their periodic arrangements. Due to their\ntopology closed magnetic nanocavities can support unique couplings of multiple\nexcitations (magnetic, optical, acoustic, spintronic). Thereby, they offer a\nunique physics playground, before unavailable, for magnetism, magneto-photonic\nand magneto-acoustic applications."
    },
    {
        "anchor": "Linking high and low temperature plasticity in bulk metallic glasses II:\n  use of a log-normal barrier energy distribution and a mean field description\n  of high temperature plasticity: A thermal activation model to describe the plasticity of bulk metallic\nglasses (Derlet and Maa\\ss, Phil. Mag. 2013, DOI: 10.1080/14786435.2013.826396)\nwhich uses a distribution of barrier energies and some aspects of under-cooled\nliquid physics is developed further. In particular, a log-normal distribution\nis now employed to describe the statistics of barrier energies. A high\ntemperature mean-field description of homogeneous macro-plasticity is then\ndeveloped and is shown to be similar to a thermal activation picture employing\na single characteristic activation energy and activation volume. In making this\ncomparison, the activation volume is interpreted as being proportional to the\naverage mean-square-value of the plastic shear strain magnitude within the\nmaterial. Also, the kinetic fragility at the glass transition temperature is\nshown to represent the effective number of irreversible structural\ntransformations available at that temperature.",
        "positive": "High-temperature quantum oscillations of the Hall resistance in bulk\n  Bi$_2$Se$_3$: Helically spin-polarized Dirac fermions (HSDF) in protected topological\nsurface states (TSS) are of high interest as a new state of quantum matter. In\nthree-dimensional (3D) materials with TSS, electronic bulk states often mask\nthe transport properties of HSDF. Recently, the high-field Hall resistance and\nlow-field magnetoresistance indicate that the TSS may coexist with a layered\ntwo-dimensional electronic system (2DES). Here, we demonstrate quantum\noscillations of the Hall resistance at temperatures up to 50 K in bulk\nBi$_2$Se$_3$ with a high electron density $n$ of about $2\\!\\cdot\\!10^{19}$\ncm$^{-3}$. From the angular and temperature dependence of the Hall resistance\nand the Shubnikov-de Haas oscillations we identify 3D and 2D contributions to\ntransport. Angular resolved photoemission spectroscopy proves the existence of\nTSS. We present a model for Bi$_2$Se$_3$ and suggest that the coexistence of\nTSS and 2D layered transport stabilizes the quantum oscillations of the Hall\nresistance."
    },
    {
        "anchor": "Atmospheric doping effects in epitaxial graphene: correlation of local\n  and global electrical measurements: We directly correlate the local (20-nm scale) and global electronic\nproperties of a device containing mono-, bi- and tri-layer epitaxial graphene\n(EG) domains on 6H-SiC(0001) by simultaneously performing local surface\npotential measurements using Kelvin probe force microscopy and global transport\nmeasurements. Using well-controlled environmental conditions, where the\nstarting state of the surface can be reproducibly defined, we investigate the\ndoping effects of N2, O2, water vapour and NO2 at concentrations representative\nof the ambient air. We show that presence of O2, water vapour and NO2 leads to\np-doping of all EG domains. However, the thicker layers of EG are significantly\nless affected by the atmospheric dopants. Furthermore, we demonstrate that the\ngeneral consensus of O2 and water vapour present in ambient air providing\nmajority of the p-doping to graphene is a common misconception. We\nexperimentally show that even the combined effect of O2, water vapour, and NO2\nat concentrations higher than typically present in the atmosphere does not\nfully replicate the state of the EG surface in ambient air. All doping effects\ncan be reproducibly reversed by vacuum annealing. Thus, for EG gas sensors it\nis essential to consider naturally occurring environmental effects and properly\nseparate them from those coming from targeted species.",
        "positive": "Effect of Sintering Temperature on Structural and Magnetic Properties of\n  Ni0.6Zn0.4Fe2O4 Ferrite: Synthesized from Nanocrystalline Powders: The effect of sintering temperatures (Ts) on the structural and magnetic\nproperties of Ni0.6Zn0.4Fe2O4 (NZFO) ferrites synthesized by conventional\ndouble sintering method has been reported. The samples are sintered at 1200,\n1250 and 1300 {\\deg}C. The X-ray diffraction (XRD) analysis reveals the\nformation of a single phase cubic spinel structure of the sample. The magnetic\nparameters such as saturation magnetization, Ms; coercive field, Hc; remanent\nmagnetization, Mr and Bohr magneton, {\\mu}B are determined and well compared\nwith reported values. The obtained values are found to be 71.94 emu/gm and 1.2\nOe for Ms and Hc, respectively at Ts=1300 oC. Curie temperature (Tc) at various\nTs has also been calculated. It is noteworthy to note that the sample with a\nvery low Hc could be used in transformer core and inductor applications."
    },
    {
        "anchor": "Colossal magnetoresistance in Ti lightly-doped Cr2Se3 single crystals\n  with layered structure: Stoichiometric Cr2Se3 single crystals are particular layer-structured\nantiferromagnets which possess noncolinear spin configuration, weak\nferromagnetic moments, moderate magnetoresistance (MR ~ 14.3%), and bad\nmetallic conductivity below the antiferromagnetic phase transition temperature.\nHere, we report an interesting >16000% colossal magnetoresistance (CMR) effect\nin Ti (1.5 atomic percent) lightly-doped Cr2Se3 single crystals. Such a CMR is\napproximately 1143 times larger than that of the stoichiometric Cr2Se3 crystals\nand is rarely observed in layered antiferromagnets and is attributed to the\nfrustrated spin configuration. Moreover, the Ti doping not only dramatically\nchanges the electronic conductivity of the Cr2Se3 crystal from a bad metal to a\nsemiconductor with a gap of ~ 15 meV, but also induces a change of the magnetic\nanisotropy of the Cr2Se3 crystal from strong out-of-plane to weak in plane.\nFurther, magnetotransport measurements reveal that the low-field MR scales with\nthe square of the reduced magnetization, which is a signature of CMR materials.\nThe layered Ti:Cr2Se3 with CMR effect could be used as 2D heterostructure\nbuilding blocks to provide colossal negative MR in spintronic devices.",
        "positive": "Prediction of the Reactivity of Argon with Xenon under High Pressure: Pressure significantly modifies the microscopic interactions in condense\nphase, leading to new patterns of bonding and unconventional chemistry. Both\nargon and xenon possess closed-shell electronic structures, which renders them\nchemically unreactive. Using unbiased structure searching techniques combined\nwith first-principles calculations, we demonstrate the reaction of argon with\nxenon at a pressure as low as 1.1 GPa, producing a novel van der Waals compound\nXeAr2, which crystallizes in the MgCu2-type Laves phase structure. Due to the\npressure-induced delocalization of the electrons in outermost shells, the\ncovalent Xe-Xe and Xe-Ar bonds have been detected which lead XeAr2 to be\nunexpectedly stable without any phase transition or decomposition at least up\nto 500 GPa."
    },
    {
        "anchor": "On the origin of incoherent magnetic exchange coupling in\n  MnBi/Fe$_x$Co$_{1-x}$ bilayer system: In this study we investigate the exchange coupling between the hard magnetic\ncompound MnBi and the soft magnetic alloy FeCo including the interface\nstructure between the two phases. Exchange spring MnBi-Fe$_x$Co$_{1-x}$ (x =\n0.65 and 0.35) bilayers with various thicknesses of the soft magnetic layer\nwere deposited onto quartz glass substrates in a DC magnetron sputtering unit\nfrom alloy targets. Magnetic measurements and density functional theory (DFT)\ncalculations reveal that a Co-rich FeCo layer leads to more coherent exchange\ncoupling. The optimum soft layer thickness is about 1 nm. In order to take into\naccount the effect of incoherent interfaces with finite roughness, we have\ncombined a cross-sectional High Resolution Transmission Electron Microscopy\n(HR-TEM) analysis with DFT calculations and micromagnetic simulations. The\nexperimental results can be consistently described by modeling assuming a\npolycrystalline FeCo layer consisting of crystalline (110) and amorphous grains\nas confirmed by HR-TEM. The micromagnetic simulations show in general how the\nthickness of the FeCo layer and the interface roughness between the hard and\nsoft magnetic phases both control the effectiveness of exchange coupling in an\nexchange spring system.",
        "positive": "A re-examination of antiferroelectric PbZrO$_3$ and PbHfO$_3$: an\n  80-atom $Pnam$ structure: First principles density functional theory (DFT) simulations of\nantiferroelectric (AFE) PbZrO$_3$ and PbHfO$_3$ reveal a dynamical instability\nin the phonon spectra of their purported low temperature $Pbam$ ground states.\nThis instability doubles the $c$-axis of $Pbam$ and condenses five new small\namplitude phonon modes giving rise to an 80-atom $Pnam$ structure. Compared\nwith $Pbam$, the stability of this structure is slightly enhanced and highly\nreproducible as demonstrated through using different DFT codes and different\ntreatments of electronic exchange & correlation interactions. This suggests\nthat $Pnam$ is a new candidate for the low temperature ground state of both\nmaterials. With this finding, we bring parity between the AFE archetypes and\nrecent observations of a very similar AFE phase in doped or electrostatically\nengineered BiFeO$_3$."
    },
    {
        "anchor": "Low Temperature Growth of Graphene on Semiconductor: The industrial realization of graphene has so far been limited by challenges\nrelated to the quality, reproducibility, and high process temperatures required\nto manufacture graphene on suitable substrates. We demonstrate that epitaxial\ngraphene can be grown on transition metal treated 6H-SiC(0001) surfaces, with\nan onset of graphitization starting around $450-500^\\circ\\text{C}$. From the\nchemical reaction between SiC and thin films of Fe or Ru, $\\text{sp}^{3}$\ncarbon is liberated from the SiC crystal and converted to $\\text{sp}^{2}$\ncarbon at the surface. The quality of the graphene is demonstrated using\nangle-resolved photoemission spectroscopy and low-energy electron diffraction.\nFurthermore, the orientation and placement of the graphene layers relative to\nthe SiC substrate is verified using angle-resolved absorption spectroscopy and\nenergy-dependent photoelectron spectroscopy, respectively. With subsequent\nthermal treatments to higher temperatures, a steerable diffusion of the metal\nlayers into the bulk SiC is achieved. The result is graphene supported on\nmagnetic silicide or optionally, directly on semiconductor, at temperatures\nideal for further large-scale processing into graphene based device structures.",
        "positive": "Large-area fabrication of low- and high-spatial-frequency laser-induced\n  periodic surface structures on carbon fibers: The formation and properties of laser-induced periodic surface structures\n(LIPSS) were investigated on carbon fibers under irradiation of fs-laser pulses\ncharacterized by a pulse duration $\\tau$ = 300 fs and a laser wavelength\n$\\lambda$ = 1025 nm. The LIPSS were fabricated in an air environment at normal\nincidence with different values of the laser peak fluence and number of pulses\nper spot. The morphology of the generated structures was characterized by using\nscanning electron microscopy, atomic force microscopy and Fast-Fourier\ntransform analyses. Moreover, the material structure and the surface chemistry\nof the carbon fibers before and after laser irradiation was analyzed by micro\nRaman spectroscopy and X-ray photoelectron spectroscopy. Large areas in the\ncm$^{2}$ range of carbon fiber arrangements were successfully processed with\nhomogenously distributed high- and low-spatial frequency LIPSS. Beyond those\ndistinct nanostructures, hybrid structures were realized for the very first\ntime by a superposition of both types of LIPSS in a two-step process. The\nfindings facilitate the fabrication of tailored LIPSS-based surface structures\non carbon fibers that could be of particular interest for e.g. fiber reinforced\npolymers and concretes."
    },
    {
        "anchor": "Analysis of ultrafast magnetization switching dynamics in\n  exchange-coupled ferromagnet-ferrimagnet heterostructures: Magnetization switching in ferromagnets has so far been limited to the\ncurrent-induced spin-orbit-torque effects. Recent observation of\nhelicity-independent all-optical magnetization switching in exchange-coupled\nferromagnet ferrimagnet heterostructures expanded the range and applicability\nof such ultrafast heat-driven magnetization switching. Here we report the\nelement-resolved switching dynamics of such an exchange-coupled system, using a\nmodified microscopic three-temperature model. We have studied the effect of i)\nthe Curie temperature of the ferromagnet, ii) ferrimagnet composition, iii) the\nlong-range RKKY exchange-coupling strength, and iv) the absorbed optical energy\non the element-specific time-resolved magnetization dynamics. The phase-space\nof magnetization illustrates how the RKKY coupling strength and the absorbed\noptical energy influence the switching time. Our analysis demonstrates that the\nthreshold switching energy depends on the composition of the ferrimagnet and\nthe switching time depends on the Curie temperature of the ferromagnet as well\nas RKKY coupling strength. This simulation anticipates new insights into\ndeveloping faster and more energy-efficient spintronics devices.",
        "positive": "Model for solute diffusion during rapid solidification of binary alloy\n  in semi-infinite volume: On the basis of local nonequilibrium approach, the one-dimensional model of\nthe solute diffusion during rapid solidification of the binary alloy in the\nsemi-infinite volume is considered. Within the scope of the model it is\nsupposed that mass transport is described by the telegrapher equation. The\nbasic assumption concerns the behavior of the diffusion flux and the solute\nconcentration at the interface. Under the condition that these quantities are\ngiven by the superposition of the exponential functions the solutions of the\ntelegrapher equation determining the flux and the solute distributions in the\nmelt have been found. On the basis of these solutions different regimes of the\nsolidification in the near surface region and the behavior of the partition\ncoefficient have been investigated. The concentration profiles in the solid\nafter complete solidification are analyzed depending on the model parameters."
    },
    {
        "anchor": "Three-dimensional bulk band dispersion in polar BiTeI with giant\n  Rashba-type spin splitting: In layered polar semiconductor BiTeI, giant Rashba-type spin-split band\ndispersions show up due to the crystal structure asymmetry and the strong\nspin-orbit interaction. Here we investigate the 3-dimensional (3D) bulk band\nstructures of BiTeI using the bulk-sensitive $h\\nu$-dependent soft x-ray angle\nresolved photoemission spectroscopy (SX-ARPES). The obtained band structure is\nshown to be well reproducible by the first-principles calculations, with huge\nspin splittings of ${\\sim}300$ meV at the conduction-band-minimum and\nvalence-band-maximum located in the $k_z=\\pi/c$ plane. It provides the first\ndirect experimental evidence of the 3D Rashba-type spin splitting in a bulk\ncompound.",
        "positive": "A learning scheme to predict atomic forces and accelerate materials\n  simulations: The behavior of an atom in a molecule, liquid or solid is governed by the\nforce it experiences. If the dependence of this vectorial force on the atomic\nchemical environment can be $learned$ efficiently with high-fidelity from\nbenchmark reference results-using \"big data\" techniques, i.e., without\nresorting to actual functional forms-then this capability can be harnessed to\nenormously speed up $in \\ silico$ materials simulations. The present\ncontribution provides several examples of how such a $force$ field for Al can\nbe used to go far beyond the length-scale and time-scale regimes accessible\npresently using quantum mechanical methods. It is argued that pathways are\navailable to systematically and continuously improve the predictive capability\nof such a learned force field in an adaptive manner, and that this concept can\nbe generalized to include multiple elements."
    },
    {
        "anchor": "Structure Optimization and Frozen Phonons in LiNbO3: The equilibrium ground-state structure of LiNbO3 in the paraelectric and\nferroelectric phases is fully optimized in a first-principles calculation using\nthe full-potential linearized augmented plane wave method. The equilibrium\nvolume, c/a ratio and all (four, in the ferroelectric phase) internal\nparameters are found to be in good agreement with the experimental data. Frozen\nphonon calculations are performed for TO-Gamma phonons corresponding to the A1\nand A2 irreducible representations of the R3c space group in the ferroelectric\nphase. The comparison with available experimental frequencies for the A1 modes\nis satisfactory (including the 6Li isotope effect), and the displacement\npatterns are unambiguously attributed. For the (Raman inactive) A2 modes,\nphonon frequencies and eigenvectors are predicted.",
        "positive": "Probing Magnetoelastic Coupling and Structural Changes in\n  Magnetoelectric Gallium Ferrite: Temperature dependent X-ray diffraction and Raman spectroscopic studies were\ncarried out on the flux grown single crystals of gallium ferrite with Ga:Fe\nratio of 0.9:1.1. Site occupancy calculations from the Rietveld refinement of\nthe X-ray data led to the estimated magnetic moment of ~0.60 \\muB /f.u. which\nwas in good agreement with the experimental data. Combination of these two\nmeasurements indicates that there is no structural phase transition in the\nmaterial between 18 K to 700 K. A detailed line shape analysis of the Raman\nmode at ~375 cm^-1 revealed a discontinuity in the peak position data\nindicating the presence of spin-phonon coupling in gallium ferrite. A\ncorrelation of the peak frequency with the magnetization data led to two\ndistinct regions across a temperature ~180 K with appreciable change in the\nspin-phonon coupling strength from ~ 0.9 cm^-1 (T < 180 K) to 0.12 cm-1 (180 K\n< T < Tc). This abrupt change in the coupling strength at ~180 K strongly\nsuggests an altered spin dynamics across this temperature."
    },
    {
        "anchor": "Nonreciprocal propagation of surface acoustic wave in Ni/LiNbO3: We have investigated surface acoustic wave propagation in Ni/LiNbO$_3$ hybrid\ndevices. We have found the absorption and phase velocity are dependent on the\nsign of wave vector in a device, which indicates the nonreciprocal propagation\ncharacteristic of systems with time reversal and spatial inversion\nsimultaneously broken symmetries. The nonreciprocity is reversed by the\n180$^\\circ$ rotation of magnetic field. Nonreciprocity seems largely dependent\non the shape of ferromagnetic Ni film. The origin of these observations is\nascribed to film shape dependent magnetoelastic coupling.",
        "positive": "Exchange enhanced anisotropy in ferromagnetic/antiferromagnetic\n  multilayers: dynamic consequences: The phenomena of exchange anisotropy is well known in terms of static\nmagnetization properties such as enhanced coercivity and magnetization loop\nshifts. These effects are primarily associated with effective anisotropies\nintroduced into the ferromagnet by exchange coupling with a strongly\nanisotropic antiferromagnet. These effective anisotropies can be understood as\nmanifestations of a more fundamental exchange induced susceptibility. We show\nthat a consequence of this view is that a class of unusual dynamic effects\nassociated with the exchange susceptibility should also exist. The effects\nbecome apparent near the ordering temperature of the antiferromagnet and affect\ndomain wall velocities, domain wall resonances, and precessional switching of\nthe ferromagnet."
    },
    {
        "anchor": "The role of phase compatibility in martensite: Shape memory alloys inherit their macroscopic properties from their mesoscale\nmicrostructure originated from the martensitic phase transformation. In a cubic\nto orthorhombic transition, a single variant of marten- site can have a\ncompatible (exact) interface with the austenite for some special lattice\nparameters in contrast to conventional austenite/twinned martensite interface\nwith a transition layer. Experimentally, the phase compat- ibility results in a\ndramatic drop in thermal hysteresis and gives rise to very stable functional\nproperties over cycling. Here, we investigate the microstructures observed in\nTi50Ni50-xPdx alloys that undergo a cubic to orthorhombic martensitic\ntransformation using a three dimensional phase field approach. We will show\nthat the simulation results are in very good agreement with transmission\nelectron microscopy observations. However, the understanding of the drop in\nthermal hysteresis requires the coupling of phase transformation with plastic\nactivity. We will discuss this point within the framework of thermoelasticity,\nwhich is a generic feature of the martensitic transformation.",
        "positive": "Theory and Simulation of Spin Transport in Antiferromagnetic\n  Semiconductors: Application to MnTe: We study in this paper the parallel spin current in an antiferromagnetic\nsemiconductor thin film where we take into account the interaction between\nitinerant spins and lattice spins. The spin model is an anisotropic Heisenberg\nmodel. We use here the Boltzmann's equation with numerical data on cluster\ndistribution obtained by Monte Carlo simulations and cluster-construction\nalgorithms. We study the cases of degenerate and non-degenerate semiconductors.\nThe spin resistivity in both cases is shown to depend on the temperature with a\nbroad maximum at the transition temperature of the lattice spin system. The\nshape of the maximum depends on the spin anisotropy and on the magnetic field.\nIt shows however no sharp peak in contrast to ferromagnetic materials. Our\nmethod is applied to MnTe. Comparison to experimental data is given."
    },
    {
        "anchor": "A Theoretical Search for the Optimum Giant Magnetoresistance: The maximum current-perpendicular-to-plane giant magnetoresistance is\nsearched for in magnetic multilayers made of Co, Ni, and Cu with disorder\nlevels similar to those found in room temperature experiments. The calculation\nis made possible by a highly optimized linear response code, which uses the\nimpurity averaged Green's function technique and a 9-band per spin tight\nbinding model. Using simulated annealing, hundreds of different configurations\nof the atomic layers are examined to find a maximum GMR of 450% in ultrathin\nNi/Cu superlattices.",
        "positive": "Contrast of LiFeAs with isostructural, isoelectronic, and\n  non-superconducting MgFeGe: Stoichiometric LiFeAs at ambient pressure is an 18 K superconductor while\nisoelectronic MgFeGe is not, despite their extremely similar electronic\nstructures. To investigate possible sources of this distinctively different\nsuperconducting behavior, we quantify the differences using first principles\ndensity functional theory, establishing first that the Fe total 3d occupations\nare identical in the two compounds. Individual 3d orbital occupations also\ndiffer very little ($\\sim 0.01$). The differences in Fermi surfaces (FSs) do\nnot seem significant; however a redistribution of bands just above the Fermi\nlevel does represent a possibly significant distinction. Because the bands and\nFSs of LiFeAs are less in agreement with experiment than for other\niron-pnictides, we study the effects of additional exchange-correlations\neffects beyond GGA (the generalized gradient approximation) by applying the\nmodified Becke-Johnson potential (mBJ) exchange potential, which gives much\nimproved bandgaps in insulators compared to GGA and might be useful for\nsemimetals such as the Fe-based superconductors. Overall, we conclude that the\nmBJ corrections do not improve the description of LiFeAs as compared to\nexperiment."
    },
    {
        "anchor": "Velocity-gauge real-time TDDFT within a numerical atomic orbital basis\n  set: The interaction of laser fields with solid-state systems can be modeled\nefficiently within the velocity-gauge formalism of real-time time dependent\ndensity functional theory (RT-TDDFT). In this article, we discuss the\nimplementation of the velocity-gauge RT-TDDFT equations for electron dynamics\nwithin a linear combination of atomic orbitals (LCAO) basis set framework.\nNumerical results obtained from our LCAO implementation, for the electronic\nresponse of periodic systems to both weak and intense laser fields, are\ncompared to those obtained from established real-space grid and Full-Potential\nLinearized Augumented Planewave approaches. Potential applications of the LCAO\nbased scheme in the context of extreme ultra-violet and soft X-ray\nspectroscopies involving core-electronic excitations are discussed.",
        "positive": "Temperature dependent magnetic damping of yttrium iron garnet spheres: We investigate the temperature dependent microwave absorption spectrum of an\nyttrium iron garnet sphere as a function of temperature (5 K to 300 K) and\nfrequency (3 GHz to 43.5 GHz). At temperatures above 100 K, the magnetic\nresonance linewidth increases linearly with temperature and shows a\nGilbert-like linear frequency dependence. At lower temperatures, the\ntemperature dependence of the resonance linewidth at constant external magnetic\nfields exhibits a characteristic peak which coincides with a non-Gilbert-like\nfrequency dependence. The complete temperature and frequency evolution of the\nlinewidth can be modeled by the phenomenology of slowly relaxing rare-earth\nimpurities and either the Kasuya-LeCraw mechanism or the scattering with\noptical magnons. Furthermore, we extract the temperature dependence of the\nsaturation magnetization, the magnetic anisotropy and the g-factor."
    },
    {
        "anchor": "Large-scale defect accumulations in Czochralski-grown silicon: Czochralski-grown silicon crystals were studied by the techniques of the\nlow-angle mid-IR-light scattering and electron-beam-induced current. The\nlarge-scale accumulations of electrically-active impurities detected in this\nmaterial were found to be different in their nature and formation mechanisms\nfrom the well-known impurity clouds in a FZ-grown silicon. A classification of\nthe large-scale impurity accumulations in CZ Si is made and point centers\nconstituting them are analyzed in this paper. A model of the large-scale\nimpurity accumulations in CZ-grown Si is also proposed. In addition, the images\nof the large-scale impurity accumulations obtained by means of the scanning\nmid-IR-laser microscopy are demonstrated.",
        "positive": "A general route to form topologically-protected surface and bulk Dirac\n  fermions along high-symmetry lines: The band inversions that generate the topologically non-trivial band gaps of\ntopological insulators and the isolated Dirac touching points of\nthree-dimensional Dirac semimetals generally arise from the crossings of\nelectronic states derived from different orbital manifolds. Recently, the\nconcept of single orbital-manifold band inversions occurring along\nhigh-symmetry lines has been demonstrated, stabilising multiple bulk and\nsurface Dirac fermions. Here, we discuss the underlying ingredients necessary\nto achieve such phases, and discuss their existence within the family of\ntransition metal dichalcogenides. We show how their three-dimensional band\nstructures naturally produce only small $k_z$ projected band gaps, and\ndemonstrate how these play a significant role in shaping the surface electronic\nstructure of these materials. We demonstrate, through spin- and angle-resolved\nphotoemission and density functional theory calculations, how the surface\nelectronic structures of the group-X TMDs PtSe$_2$ and PdTe$_2$ are host to up\nto five distinct surface states, each with complex band dispersions and spin\ntextures. Finally, we discuss how the origin of several recently-realised\ninstances of topological phenomena in systems outside of the TMDs, including\nthe iron-based superconductors, can be understood as a consequence of the same\nunderlying mechanism driving $k_z$-mediated band inversions in the TMDs."
    },
    {
        "anchor": "On the Role of Charge Transfer Excitations in Non-Fullerene Acceptors\n  for Organic Photovoltaics: Through the development of new non-fullerene electron acceptor (NFA)\nmaterials, such as Y6 and its molecular derivatives, the power conversion\nefficiencies of organic photovoltaics (OPVs) have now exceeded 19%. However,\ndespite this rapid progress, our fundamental understanding of the unique\noptical and electronic properties of these Y-series NFAs is lacking, and this\ncurrently limits progress in material design. In this work, we provide a\ndetailed computational-experimental characterisation of the archetypal NFA, Y6.\nTo explain the significant broadening and red shift of the absorption spectrum\nobserved when moving from the solution phase to the solid state, we first rule\nout more typical causes, such as J-aggregation. Instead, by considering the\nrole of charge transfer (CT) excitations and their mixing with Frenkel exciton\n(FE) states, we can computationally reproduce the experimental absorption\nspectra of Y6 with excellent accuracy. Using transient absorption spectroscopy,\nwe provide evidence for this dense manifold of FE-CT hybrid electronic\nexcitations in Y6 through the prominent sub-picosecond relaxation events\nfollowing supra band gap excitation. Furthermore, through sub band gap\nexcitation, we also find states with polaronic character in Y6 that are in a\ndynamic equilibrium with the FE-CT hybrid states. Magnetic resonance\nspectroscopies reveal that these polaronic states are polaron pairs, most\nlikely located on neighbouring Y6 molecules, not free charge carriers, as has\nbeen previously suggested. Thus, this new understanding of how the solid-state\npacking motif directly controls the optical and electronic properties of\nY-series NFAs opens the door to intelligently design NFA materials to further\nincrease OPV performance.",
        "positive": "Band Gap Tuning of DC Reactively Sputtered ZnON Thin Films: Zinc oxynitride (ZnO$_x$N$_y$) has recently emerged as a highly promising\nband gap-tunable semiconductor material for optoelectronic applications. In\nthis study, a novel DC reactive sputtering protocol was developed to fabricate\nZnO$_x$N$_y$ films with varying elemental concentrations, by precisely\ncontrolling the working pressure. The band gap was rigorously analyzed using\nUV-Visible spectroscopy, which was complemented by EDAX spectroscopy to\ndetermine the variations in the elemental composition. The correlation between\nthe microstructure and band gap was investigated through the application of\nAFM, XRD, and Raman spectroscopy, while the Urbach theorem was used to evaluate\nthe defect states. This study revealed the existence of intermediate structures\nformed during the tuning of the band gap, which can have important implications\nfor future research aimed at developing heterostructures and 2D superlattices\nfor photonics applications."
    },
    {
        "anchor": "Thermo-mechanical properties of nitrogenated holey graphene (C2N): A\n  comparison of machine-learning-based and classical interatomic potentials: Thermal and mechanical properties of two-dimensional nanomaterials are\ncommonly studied by calculating force constants using the density functional\ntheory (DFT) and classical molecular dynamics (MD) simulations. Although DFT\nsimulations offer accurate estimations, the computational cost is high. On the\nother hand, MD simulations strongly depend on the accuracy of interatomic\npotentials. Here, we investigate thermal conductivity and elastic modulus of\nnitrogenated holey graphene (C2N) using passively fitted machine-learning\ninteratomic potentials (MLIPs), which depend on computationally inexpensive\nab-initio molecular dynamics trajectories. Thermal conductivity of C2N is\ninvestigated via MLIP-based non-equilibrium molecular dynamics simulations\n(NEMD). At room temperature, the lattice thermal conductivity of 85.5 W/m-K and\neffective phonon mean free path of 37.16 nm are found. By carrying out uniaxial\ntension simulations, the elastic modulus, ultimate strength, and fractural\nstrain of C2N are predicted to be 390 GPa, 42 GPa, and 0.29, respectively. It\nis shown that the passively fitted MLIPs can be employed as an efficient\ninteratomic potential to obtain the thermal conductivity and elastic modulus of\nC2N utilizing classical MD simulations. Moreover, the possibility of employing\nMLIPs to simulate C2N with point defects has been investigated. By training\nMLIP with point defect configurations, the mechanical properties of defective\nstructures were studied. Although using the MLIP is more costly than classical\ninteratomic potentials, it could efficiently predict the thermal and mechanical\nproperties of 2D nanostructures.",
        "positive": "Synchronous relaxation algorithm for parallel kinetic Monte Carlo: We investigate the applicability of the synchronous relaxation (SR) algorithm\nto parallel kinetic Monte Carlo simulations of simple models of thin-film\ngrowth. A variety of techniques for optimizing the parallel efficiency are also\npresented. We find that the parallel efficiency is determined by three main\nfactors $-$ the calculation overhead due to relaxation iterations to correct\nboundary events in neighboring processors, the (extreme) fluctuations in the\nnumber of events per cycle in each processor, and the overhead due to\ninterprocessor communications. Due to the existence of fluctuations and the\nrequirement of global synchronization, the SR algorithm does not scale, i.e.\nthe parallel efficiency decreases logarithmically as the number of processors\nincreases. The dependence of the parallel efficiency on simulation parameters\nsuch as the processor size, domain decomposition geometry, and the ratio $D/F$\nof the monomer hopping rate $D$ to the deposition rate $F$ is also discussed."
    },
    {
        "anchor": "Half-Heusler Compounds as a New Class of Three-Dimensional Topological\n  Insulators: Using first-principles calculations within density functional theory, we\nexplore the feasibility of converting ternary half-Heusler compounds into a new\nclass of three-dimensional topological insulators (3DTI). We demonstrate that\nthe electronic structure of unstrained LaPtBi as a prototype system exhibits\ndistinct band-inversion feature. The 3DTI phase is realized by applying a\nuniaxial strain along the [001] direction, which opens a bandgap while\npreserving the inverted band order. A definitive proof of the strained LaPtBi\nas a 3DTI is provided by directly calculating the topological Z2 invariants in\nsystems without inversion symmetry. We discuss the implications of the present\nstudy to other half-Heusler compounds as 3DTI, which, together with the\nmagnetic and superconducting properties of these materials, may provide a rich\nplatform for novel quantum phenomena.",
        "positive": "Exploring librational pathways with on-the-fly machine-learning force\n  fields: Methylammonium molecules in MAPbX$_3$ (X=I, Br, Cl) perovskites: Two seemingly similar crystal structures of the low-temperature (~100 K)\nMAPbX$_3$ (X=I,Br,Cl) perovskites, but with different relative Methylammonium\n(MA) ordering, have appeared as representatives of this orthorhombic phase.\nDistinguishing them by X-ray diffraction experiments is difficult and\nconventional first-principles based molecular-dynamics approaches are often too\ncomputationally intensive to be feasible. Therefore, to determine the\nthermodynamically stable structure, we use a recently introduced on-the-fly\nMachine-Learning Force Field method, which reduces the computation time from\nyears to days. The molecules exhibit a large degree of anharmonic motion\ndepending on temperature: i.e. rattling, twisting and tumbling. We observe the\ncrystal's 'librational pathways' while slowly heating it in isothermal-isobaric\nsimulations. Marked differences in the thermal evolution of structural\nparameters allow us to determine the real structure of the system via a\ncomparison with experimentally determined crystal structures."
    },
    {
        "anchor": "Lattice thermal conductivity of Ti$_x$Zr$_y$Hf$_{1-x-y}$NiSn\n  half-Heusler alloys calculated from first principles: Key role of nature of\n  phonon modes: In spite of their relatively high lattice thermal conductivity\n$\\kappa_{\\ell}$, the XNiSn (X=Ti, Zr or Hf) half-Heusler compounds are good\nthermoelectric materials. Previous studies have shown that $\\kappa_{\\ell}$ can\nbe reduced by sublattice-alloying on the X-site. To cast light on how the alloy\ncomposition affects $\\kappa_\\ell$, we study this system using the phonon\nBoltzmann-transport equation within the relaxation time approximation in\nconjunction with density functional theory.The effect of alloying through\nmass-disorder scattering is explored using the virtual crystal approximation to\nscreen the entire ternary Ti$_x$Zr$_{y}$Hf$_{1-x-y}$NiSn phase diagram. The\nlowest lattice thermal conductivity is found for the Ti$_x$Hf$_{1-x}$NiSn\ncompositions; in particular, there is a shallow minimum centered at\nTi$_{0.5}$Hf$_{0.5}$NiSn with $\\kappa_l$ taking values between 3.2 and 4.1 W/mK\nwhen the Ti content varies between 20 and 80\\%. Interestingly, the overall\nbehavior of mass-disorder scattering in this system can only be understood from\na combination of the nature of the phonon modes and the magnitude of the mass\nvariance. Mass-disorder scattering is not effective at scattering acoustic\nphonons of low energy. By using a simple model of grain boundary scattering, we\nfind that nanostructuring these compounds can scatter such phonons effectively\nand thus further reduce the lattice thermal conductivity; for instance,\nTi$_{0.5}$Hf$_{0.5}$NiSn with a grain size of $L= 100$ nm experiences a 42\\%\nreduction of $\\kappa_{\\ell}$ compared to that of the single crystal.",
        "positive": "Structural, vibrational and electronic properties of Nb substituted\n  orthovanadates LaV$_{1-x}$Nb$_x$O$_4$: We investigate the structural, vibrational, morphological, and electronic\nproperties of Nb substituted orthovanadate LaV$_{1-x}$Nb$_x$O$_4$ samples\nprepared by the solid-state reaction method. The x-ray diffraction (XRD)\nanalysis reveals the presence of three crystal structures [monoclinic monazite\n($m-m$) type for the $x=$ 0, two-phase equilibrium of monoclinic monazite\n($m-m$) and tetragonal scheelite ($t-s$) type for the 0.2$\\leq$$x$$\\leq$0.8,\nand monoclinic fergusonite ($m-f$) type for the $x=$ 1 samples] with an\nincrease in Nb$^{5+}$ concentration. The Raman spectroscopy and x-ray\nphotoelectron spectroscopy (XPS) were employed to study the vibrational and\nelectronic properties of all the samples, respectively. In order to choose an\nexcitation wavelength that does not cause undesirable fluorescence and has\nobservable intensities of all the vibrational modes, the Raman spectra are\ncollected using 532 nm, 633 nm, and 785 nm laser lines. With increasing the\nNb$^{5+}$ concentration, new Raman modes associated with Nb-bonds are clearly\nvisible and the intensity of V-bonds assigned modes is decreasing. The XPS\nanalysis shows the unchanged 3+ oxidation state of La ion where the intensity\nof the V 2$p$ core-level decreases while the Nb 3$d$ core-level increases with\n$x$. The equal spin-orbit energy splitting of the states is confirmed by the\naverage energy difference (across La core-level spectra for all the samples)\nfor state I as well as bonding and anti-bonding of state II. Interesting, the\nrelative intensity of La 3$d$ state I and state II show systematic change with\nNb doping altering the metal ligand overlap. We discuss and provide insight\ninto the evolution of the structural, morphological, and chemical features with\nNb substitution in LaV$_{1-x}$Nb$_x$O$_4$ samples."
    },
    {
        "anchor": "Momentum-resolved resonant photoelectron spectroscopic study for\n  1T-TiSe$_2$: Observation of negative q in the Fano resonance due to\n  inter-atomic interaction in the valence band: The remarkable properties of (1T-)TiSe$_2$ among the transition metal\ndichalcogenides have attracted the attention of many researchers due to its\npeculiar behavior during the charge density wave (CDW) transition. Therefore,\nit is highly desirable to study its electronic structure down to the atomic\norbitals. In the present research, we applied momentum-resolved resonant\nphotoelectron spectroscopy to study TiSe$_2$ at the Ti2p-Ti3d absorption edge\nby using a momentum microscope, which can simultaneously detect the electronic\nstates in a wide $(k_x,k_y)$ range. We have also used constant initial state\n(CIS) spectroscopy and density functional theory (DFT) calculations to reveal\nthe hybridization between the Ti3d and Se4p orbitals within the valence band at\nthe Gamma point at room temperature. In addition, an interesting result comes\nfrom our analysis of the CIS spectrum for the energy band located at a binding\nenergy of 2 eV at the M-point. This band, mainly composed of the Se4p orbital,\nexhibited a Fano line profile at the Ti2p edge, with a negative value of the\nparameter \"$q$\". This is the first clear evidence of the inter-atomic\ninteraction during the valence band photoelectron emission process. This\nbehavior differs significantly from the standard resonant photoelectron\nemission, which usually involves intra-atomic interactions. It also differs\nfrom the multi-atom resonant photoelectron emission (MARPE) observed in the\ncore-level photoelectron emission, as we focus on the photoelectron emission\nfrom the valence band in this research.",
        "positive": "Uniform curves for van der Waals interaction between single-wall carbon\n  nanotubes: We report very simple and accurate algebraic expressions for the van der\nWaals (vdW) potentials and the forces between two parallel and crossed carbon\nnanotubes. The Lennard-Jones potential for two carbon atoms and the method of\nthe smeared out approximation suggested by L.A. Girifalco were used. It is\nfound that interaction between parallel and crossed tubes are described by\ndifferent uniform curves which depend only on dimensionless distance. The\nexplicit functions for equilibrium vdW distances, well depths, and maximal\nattractive forces have been given. These results may be used as a guide for\nanalysis of experimental data to investigate interaction between nanotubes of\nvarious natures."
    },
    {
        "anchor": "Room temperature and low-field resonant enhancement of spin Seebeck\n  effect in partially compensated magnets: Resonant enhancement of spin Seebeck effect (SSE) due to phonons was recently\ndiscovered in Y3Fe5O12 (YIG). This effect is explained by hybridization between\nthe magnon and phonon dispersions. However, this effect was observed at low\ntemperatures and high magnetic fields, limiting the scope for applications.\nHere we report observation of phonon-resonant enhancement of SSE at room\ntemperature and low magnetic field. We observed in Lu2BiFe4GaO12 and\nenhancement 700 % greater than that in a YIG film and at very low magnetic\nfields around 10-1 T, almost one order of magnitude lower than that of YIG. The\nresult can be explained by the change in the magnon dispersion induced by\nmagnetic compensation due to the presence of non-magnetic ion substitutions.\nOur study provides a way to tune the magnon response in a crystal by chemical\ndoping with potential applications for spintronic devices.",
        "positive": "Optical properties of exciton in two-dimensional transition metal\n  dichalcogenide nanobubbles: Strain in two-dimensional (2D) transition metal dichalcogenide (TMD) has led\nto localized states with exciting optical properties, in particular in view of\ndesigning one photon sources. The naturally formed of the MoS2 monolayer\ndeposed on hBN substrate leads to a reduction of the bandgap in the strained\nregion creating a nanobubble. The photogenerated particles are thus confined in\nthe strain-induced potential. Using numerical diagonalization, we simulate the\nspectra of the confined exciton states, their oscillator strengths and\nradiative lifetimes. We show that a single state of the confined exciton is\noptically active, which suggests that the MoS2/hBN nanobubble is a good\ncandidate for the realisation of single-photon sources. Furthermore, the\nexciton binding energy, oscillator strength and radiative lifetime are enhanced\ndue to the confinement effect."
    },
    {
        "anchor": "Thermodynamics of the Heusler alloy Co_2-xMn_1+xSi: a combined density\n  functional theory and cluster expansion study: Previous studies indicated that intrinsic point defects play a crucial role\nfor the density of states of ferromagnetic half-metals in the band gap region:\nAt large concentrations, defect-derived bands might close the gap at the Fermi\nenergy in the minority spin channel. In this work, structural disorder in the\nCo- and Mn-sublattices of the full Heusler alloy Co_2-xMn_1+xSi (-1 < x < 2) is\ninvestigated with a cluster expansion approach, parametrized using all-electron\ndensity functional theory calculations. By establishing two separate cluster\nexpansions, one for the formation energy and one for the total spin moment, we\nare in position to determine the stability of different configurations, to\npredict new (also half-metallic) ground states and to extend the known\nSlater-Pauling rule for ideally stoichiometric Heusler alloys to\nnon-stoichiometric, Mn-rich compositions. This enables us to identify\npotentially half-metallic structures in the Mn-rich region. With the help of\nMonte Carlo simulations based on the cluster expansion, we establish\ntheoretically that Co_2-xMn_1+xSi close to the stoichiometric composition ought\nto show a high degree of structural order in thermodynamic equilibrium. Hence,\nsamples prepared with the correct stoichiometry should indeed be half-metallic\nafter thermal annealing. Moreover, we predict that adding a small amount of Mn\nto stoichiometric Co_2MnSi allows to suppress the thermally activated formation\nof detrimental Co antisites. At Mn-rich compositions (x>1), the ordered ground\nstate structures predicted for zero temperature are found to be thermally\nunstable and to decompose into Co2MnSi and Mn3Si above room temperature.",
        "positive": "Cauchy magnetic field component and magnitude distribution studied by\n  the zero-field muon spin relaxation technique: Zero-field muon spin relaxation (ZF-$\\mu $SR) data for dilute spin magnetic\nsystems have been widely interpreted with what is called a Kubo-Toyabe form\nbased on a Lorentzian distribution of local field components. We derive here\nthe proper magnetic field \\textit{magnitude} distribution using independent and\nuncorrelated \\textit{component} distributions. Our result is then compared to\nthe previously accepted formula for ZF-$\\mu $SR. We discuss the origins of the\nmagnetic field component and magnitude distributions. Further we found that\nafter rescaling the magnetic field, the differences that are amenable to\nexperimental examination are quite small, although the interpretations behind\nthem are quite different."
    },
    {
        "anchor": "Structure And Properties of Nanoparticles Formed under Conditions of\n  Wire Electrical Explosion: Structure and properties of nanoparticles formed under conditions of wire\nelectrical explosion were studied. It was shown that the state of WEE power\nparticles can be characterized as a metastable state. It leads to an increased\nstability of nanopowders at normal temperatures and an increased reactivity\nduring heating, which is revealed in the form of threshold phenomena.",
        "positive": "Semimetallic \"Electride Bands\" Derived from Interlayer Electrons in\n  Quasi-Two-Dimensional Electride Y$_2$C: Two-dimensional (2D) electrides are a new concept material in which anionic\nelectrons are confined in the interlayer space between positively charged\nlayers. We have performed angle-resolved photoemission spectroscopy\nmeasurements on Y$_2$C, which is a possible 2D electride, in order to verify\nthe formation of 2D electride states in Y$_2$C. We clearly observe the\nexistence of semimetallic \"electride bands\" near the Fermi level, as predicted\nby ${ab}$ ${initio}$ calculations, conclusively demonstrating that Y$_2$C is a\nquasi-2D electride with electride bands derived from interlayer anionic\nelectrons."
    },
    {
        "anchor": "Self-aligned process for forming microlenses at the tips of vertical\n  silicon nanowires by atomic layer deposition: The microlens is a key enabling technology in optoelectronics, permitting\nlight to be efficiently coupled to and from devices such as image sensors and\nlight-emitting diodes. Their ubiquitous nature motivates the development of new\nfabrication techniques, since existing methods face challenges as microlenses\nare scaled to smaller dimensions. Here, we demonstrate the formation of\nmicrolenses at the tips of vertically-oriented silicon nanowires via a rapid\natomic layer deposition (ALD) process. The nature of the process is such that\nthe microlenses are centered on the nanowires, and there is a self-limiting\neffect on the final sizes of the microlenses arising from the nanowire spacing.\nFinite difference time domain electromagnetic simulations are performed of\nmicrolens focusing properties, including showing their ability to enhance\nvisible-wavelength absorption in silicon nanostructures.",
        "positive": "Photoconduction in CDW conductors: Photoconduction study of quasi-1D conductors allows to distinguish between\nthe single-particle and collective {\\it linear} conduction, investigate the\neffect of screening on collective transport and obtain interesting new details\nof the electronic energy structure of pure and doped CDW conductors. Here we\npresent results of photoconduction study in quasi-1D conductors o-TaS$_3$,\nK$_{0.3}$MoO$_3$, and NbS$_3$(I)."
    },
    {
        "anchor": "Exploration of the Microstructure Space in TiAlZrN Ultra-Hard\n  Nanostructured Coatings: Ti$_{1-x-y}$Al$_{x}$Zr$_{y}$N cubic alloys within the 25-70\\% Al composition\nrange have high age-hardening capabilities due to metastable phase transition\npathways at high temperatures. They are thus ideal candidates for ultra-hard\nnano-coating materials. There is growing evidence that this effect is\nassociated with the elasto-chemical field-induced phase separation into\ncompositionally-segregated nanocrystaline nitride phases. Here, we studied the\nmicrostructural evolution in this pseudo-ternary system within spinodal regions\nat 1200 $^\\circ$C by using an elasto-chemical phase field model. Our\nsimulations indicate that elastic interactions between nitride nano-domains\ngreatly affect not only the morphology of the microstructure but also the local\nchemical phase equilibria. In Al-rich regions of the composition space we\nfurther observe the onset of the transformation of AlN-rich phases into their\nequilibrium wurtzite crystal structure. This work points to a wide palette of\nmicrostructures potentially accessible to these nitride systems and their\ntailoring is likely to result in significant improvements in the performance of\ntransition metal nitride-based coating materials.",
        "positive": "Effect of annealing on the magnetic properties of zinc ferrite thin\n  films: We report on the magnetic properties of zinc ferrite thin film deposited on\nSrTiO$_3$ single crystal using pulsed laser deposition. X-ray diffraction\nresult indicates the highly oriented single phase growth of the film along with\nthe presence of the strain. In comparison to the bulk antiferromagnetic order,\nthe as-deposited film has been found to exhibit ferrimagnetic ordering with a\ncoercive field of 1140~Oe at 5~K. A broad maximum, at $\\approx$105~K, observed\nin zero-field cooled magnetization curve indicates the wide grain size\ndistribution for the as-deposited film. Reduction in magnetization and blocking\ntemperature has been observed after annealing in both argon as well as oxygen\natmospheres, where the variation was found to be dependent on the annealing\ntemperature."
    },
    {
        "anchor": "Single photon emission from ZnO nanoparticles: Room temperature single photon emitters are very important resources for\nphotonics and emerging quantum technologies. In this work we study single\nphoton emission from defect centers in 20 nm zinc oxide (ZnO) nanoparticles.\nThe emitters exhibit bright broadband fluorescence in the red spectral range\ncentered at 640 nm with polarized excitation and emission. The studied emitters\nshowed continuous blinking, however, bleaching can be suppressed using a\npolymethyl methacrylate (PMMA) coating. Furthermore, hydrogen termination\nincreased the density of single photon emitters. Our results will contribute to\nthe identification of quantum systems in ZnO.",
        "positive": "From bi-layer to tri-layer Fe nanoislands on Cu3Au(001): Self assembly on suitably chosen substrates is a well exploited root to\ncontrol the structure and morphology, hence magnetization, of metal films. In\nparticular, the Cu3Au(001) surface has been recently singled out as a good\ntemplate to grow high spin Fe phases, due to the close matching between the\nCu3Au lattice constant (3.75 Angstrom) and the equilibrium lattice constant for\nfcc ferromagnetic Fe (3.65 Angstrom). Growth proceeds almost layer by layer at\nroom temperature, with a small amount of Au segregation in the early stage of\ndeposition. Islands of 1-2 nm lateral size and double layer height are formed\nwhen 1 monolayer of Fe is deposited on Cu3Au(001) at low temperature. We used\nthe PhotoElectron Diffraction technique to investigate the atomic structure and\nchemical composition of these nanoislands just after the deposition at 140 K\nand after annealing at 400 K. We show that only bi-layer islands are formed at\nlow temperature, without any surface segregation. After annealing, the Fe atoms\nare re-aggregated to form mainly tri-layer islands. Surface segregation is\nshown to be inhibited also after the annealing process. The implications for\nthe film magnetic properties and the growth model are discussed."
    },
    {
        "anchor": "Elastic Li\u00e9nard-Wiechert potentials of dynamical dislocations from\n  tensor gauge theory: The dynamics of defect excitations in crystalline solids is necessary to\nunderstand the macroscopic low-energy properties of elastic media. We use\nfracton-elasticity duality to systematically study the defect dynamics and\ninteractions in the linear isotropic medium. We derive the explicit expressions\nfor the dual gauge potentials for moving dislocations and the resulting\nJefimenko's equations. We also compute stresses and strains. The study includes\ntwo physical situations: when vacancies are absent and when they are present in\nthe solid. If defects are present we show a constraint that needs to be\nsatisfied by the when they climb perpendicularly to their Burgers vector. Next,\nwe extend the classic result of Peach and Koehler for the force between two\ndislocations and show that, similarly, to moving charges in electrodynamics, it\nis non-reciprocal, when one dislocation is moving. We argue that our formalism\ncan be extended beyond Cauchy's elasticity by exploiting the simplifications\nprovided by the dual gauge formulation of elastic stresses.",
        "positive": "How Charge Carrier Exchange between Absorber and Contact influences Time\n  Constants in the Frequency Domain Response of Perovskite Solar Cells: A model is derived for the frequency- and time-domain opto-electronic\nresponse of perovskite solar cells (PSCs) that emphasizes the role of charge\ncarrier exchange, .i.e. extraction and injection, from (to) the perovskite\nthrough the transport layer to (from) the collecting electrode. This process is\ndescribed by a charge carrier exchange velocity that depends on the mobility\nand electric field inside the transport layer. The losses implied by this\nprocess are modelled in an equivalent circuit model in the form of a\nvoltage-dependent transport layer resistance. The analysis of the model\npredicts that the voltage dependence of the measured time constants allows\ndiscriminating situations where the transport layer properties dominate the\nexperimental response. Application of this method to experimental impedance\nspectroscopy data identifies charge extraction velocities between 1-100 cm/s at\n1 sun open-circuit conditions for p-i-n PSCs with PTAA as the hole transport\nlayer, that corresponds to transport layer mobilities between 10^-4 - 3 x 10^-3\ncm^2V^-1s^-1. The model paves the way for accurate estimation of photocurrent\nand fill factor losses in PSCs caused by the low mobilities in the transport\nlayers, using small perturbation measurements in the time and frequency domain."
    },
    {
        "anchor": "Quantum Physisorption of Methane and Carbon Dioxide within Nanoporous\n  Materials: Although numerous investigations reveal the gas physisorption characteristics\nof porous materials and a variety of theories have also established to describe\ngas physisorption during the past century, the essence of physisorption\nbehavior of gas within nanoscale space is still indistinct. We find that the\nphysisorption behavior of complex molecular system of methane and carbon\ndioxide within nanoporous materials exhibits a quantum effect. Based on this\nquantum effect, we established a physisorption equation from the perspective of\nquantum mechanics to re-understand the basic principles of gas physisorption\nwithin nanopores. Energy level transition triggers gas physisorption, and\nnon-uniform spatial distribution of energy-quantized molecules within nanopores\ndominates the gas physisorption behavior. The spatial distribution of gas\nmolecules can be adjusted by temperature, pressure and potential energy field.\nThis result contributes to understand and predict the physisorption behavior of\nCH4 and CO2 within nanoporous materials.",
        "positive": "Interplay between exchange split Dirac and Rashba-type surface states in\n  MnBi$_2$Te$_4$/BiTeI interface: Based on the ab initio calculations, we study the electronic structure of the\nBiTeI/MnBi2Te4 heterostructure interface composed of the anti-ferromagnetic\ntopological insulator MnBi$_2$Te$_4$ and the polar semiconductor trilayer\nBiTeI. We found significant difference in electronic properties at different\ntypes of contact between substrate and the overlayer. While the case of Te-Te\ninterface forms natural expansion of the substrate, when Dirac cone state\nlocates mostly in the polar overlayer region and undergoes slight exchange\nsplitting, Te-I contact is the source of four-band state contributed by the\nsubstrate Dirac cone and Rashba-type state of the polar trilayer. Owing to\nmagnetic proximity, the pair of Kramers degeneracies for this state are lifted,\nwhat produces Hall response in transport regime. We believe, our findings\nprovide new opportunities to construct novel type spintronic devices."
    },
    {
        "anchor": "Complete topology of cells, grains, and bubbles in three-dimensional\n  microstructures: We introduce a general, efficient method to completely describe the topology\nof individual grains, bubbles, and cells in three-dimensional polycrystals,\nfoams, and other multicellular microstructures. This approach is applied to a\npair of three-dimensional microstructures that are often regarded as close\nanalogues in the literature: one resulting from normal grain growth (mean\ncurvature flow) and another resulting from a random Poisson-Voronoi\ntessellation of space. Grain growth strongly favors particular grain\ntopologies, compared with the Poisson-Voronoi model. Moreover, the frequencies\nof highly symmetric grains are orders of magnitude higher in the the grain\ngrowth microstructure than they are in the Poisson-Voronoi one. Grain topology\nstatistics provide a strong, robust differentiator of different cellular\nmicrostructures and provide hints to the processes that drive different classes\nof microstructure evolution.",
        "positive": "Continuous hydrothermal flow synthesis of Gd-doped CeO2 (GDC)\n  nanoparticles for inkjet printing of SOFC electrolytes: GdxCe1-xO2-d (GDC) nanoparticles were synthesized, using continuous\nhydrothermal flow synthesis. By varying the synthesis conditions, particle size\nand morphology could be tailored. Here, particle sizes between 6 and 40 nm with\npolyhedral or octahedral shape could be obtained. Gd0.2Ce0.8O2-d nanoparticles\nwere further processed into inks for inkjet printing. Despite the small\nparticle size/large surface area, inks with excellent printing behavior were\nformulated. For proof-of-concept, thin GDC layers were printed on a) green\nNiO-GDC substrates, and on b) presintered NiO-YSZ substrates. While no dense\nlayers could be obtained on the green NiO-GDC substrates, GDC nanoparticles\nprinted on NiO-YSZ substrates formed a dense continuous layer after firing."
    },
    {
        "anchor": "Mechanisms of bulk and surface diffusion in metallic glasses determined\n  from molecular dynamics simulations: The bulk and surface dynamics of Cu50Zr50 metallic glass were studied using\nclassical molecular dynamics (MD) simulations. As the alloy undergoes cooling,\nit passes through liquid, supercooled, and glassy states. While bulk dynamics\nshowed a marked slowing down prior to glass formation, with increasing\nactivation energy, the slowdown in surface dynamics was relatively subtle. The\nsurface exhibited a lower glass transition temperature than the bulk, and the\ndynamics preceding the transition were accurately described by a\ntemperature-independent activation energy. Surface dynamics were much faster\nthan bulk at a given temperature in the supercooled state, but surface and bulk\ndynamics were found to be very similar when compared at their respective glass\ntransition temperatures. The manifestation of dynamical heterogeneity, as\ncharacterized by the non-Gaussian parameter and breakdown of the\nStokes-Einstein equation, was also similar between bulk and surface for\ntemperatures scaled by their respective glass transition temperatures.\nIndividual atom motion was dominated by a cage and jump mechanism in the glassy\nstate for both the bulk and surface. We utilize this cage and jump mechanisms\nto separate the activation energy for diffusion into two parts: (i)\ncage-breaking barrier (Q1), associated with the rearrangement of neighboring\natoms to free up space and (ii) the subsequent jump barrier (Q2). It was\nobserved that Q1 dominates Q2 for both bulk and surface diffusion, and the\ndifference in activation energies for bulk and surface diffusion mainly arose\nfrom the differences in cage-breaking barrier Q1.",
        "positive": "Incommensurate spin and orbital magnetism of Mn atomic chains on W(110)\n  surface: Stabilization of unusual spin-orbit driven magnetic orderings are achieved\nfor chains of Mn atoms deposited on a W(110) substrate. First-principles\nelectronic structure calculations show that the ground state spin configuration\nis non-collinear, forming spirals as a result of a competition between nearest\nand next-nearest neighbour exchange interactions. The orbital magnetic moments\nare also found to exhibit non-collinear ordering, that interestingly for some\nsystems is incommensurate with the spin arrangement. We attribute such an\nexotic behaviour to the competition between the and spin-orbital interaction\nand crystal-field splitting effects. Model calculations based on this\nassumption reproduce the main findings observed in the first-principles\ncalculations."
    },
    {
        "anchor": "Structural, electronic and optical characterization of bulk platinum\n  nitrides: a first-principles study: We present a detailed quantum mechanical non empirical DFT investigation of\nthe energy-optimized geometries, phase stabilities and electronic properties of\nbulk Pt3N, PtN and PtN2 in a set of twenty different crystal structures.\nStructural preferences for these three stoichiometries were analyzed and\nequilibrium structural parameters were determined. We carefully investigated\nthe band-structure and density of states of the relatively most stable phases.\nFurther, GW_0 calculations within the random-phase approximation (RPA) to the\ndielectric tensor were carried out to derive their frequency-dependent optical\nconstants of the most likely candidates for the true crystal structure.\nObtained results were comprehensively compared to previous calculations and to\nexperimental data.",
        "positive": "Substrate-Dependence of Monolayer MoS$_2$ Thermal Conductivity and\n  Thermal Boundary Conductance: The thermal properties of two-dimensional (2D) materials, like MoS$_2$, are\nknown to be affected by interactions with their environment, but this has\nprimarily been studied only with SiO$_2$ substrates. Here, we compare the\nthermal conductivity (TC) and thermal boundary conductance (TBC) of monolayer\nMoS$_2$ on amorphous (a-) and crystalline (c-) SiO$_2$, AlN, Al$_2$O$_3$, and\n$\\textit{h}$-BN monolayers using molecular dynamics. The room temperature TC of\nMoS$_2$ is ~38 Wm$^{-1}$K$^{-1}$ on amorphous substrates and up to ~68\nWm$^{-1}$K$^{-1}$ on crystalline substrates, with most of the difference due to\nsubstrate interactions with long-wavelength MoS$_2$ phonons (< 2 THz). An\n$\\textit{h}$-BN monolayer used as a buffer between MoS$_2$ and the substrate\ncauses the MoS$_2$ TC to increase by up to 50%. Length-dependent calculations\nreveal TC size effects below ~2 $\\mu$m and show that the MoS$_2$ TC is size-\nbut not substrate-limited below ~100 nm. We also find that the TBC of MoS$_2$\nwith c-Al$_2$O$_3$ is over twice that with c-AlN despite a similar MoS$_2$ TC\non both, indicating that the TC and TBC could be tuned independently. Finally,\nwe compare the thermal resistance of MoS$_2$ transistors on all substrates to\nshow that MoS$_2$ TBC is the most important parameter for heat removal for\nlong-channel (> 150 nm) devices, while TBC and TC are equally important for\nshort channels. This work provides important insights for electro-thermal\napplications of 2D materials on various substrates."
    },
    {
        "anchor": "Computation and visualization of accessible reciprocal space and\n  resolution element in high-resolution X-ray diffraction mapping: An approach to visualize the accessible reciprocal space accounting the\ngoniometer angles limitation and the resolution element in the reciprocal space\nis presented. The shapes of the accessible reciprocal space region for coplanar\nand non-coplanar geometries are given employing the additional degree of\nfreedom provided by detector arm. The examples of the resolution elements in\ndifferent points of the reciprocal space are shown. The equations obtained\npermit to find these regions and to calculate the experimental geometry to\nobtain the diffraction from any accessible reflections, which makes a further\nextension of previously reported methods. The introduced algorithm has been\ntestified by experimental measurements of reciprocal space maps in coplanar and\nnon-coplanar geometries. The examples of the resolution elements in different\npoints of the reciprocal space are calculated to illustrate the method\nproposed.",
        "positive": "Machine-learned approximations to Density Functional Theory Hamiltonians: Large scale Density Functional Theory (DFT) based electronic structure\ncalculations are highly time consuming and scale poorly with system size. While\nsemi-empirical approximations to DFT result in a reduction in computational\ntime versus ab initio DFT, creating such approximations involves significant\nmanual intervention and is highly inefficient for high-throughput electronic\nstructure screening calculations. In this letter, we propose the use of\nmachine-learning for fast and accurate prediction of DFT Hamiltonians. Using\nsuitable representations of atomic neighborhoods and Kernel Ridge Regression,\nwe show that an accurate and transferable prediction of DFT Hamiltonians for a\nvariety of material environments can be achieved. Electronic transmission\nspectra computed using predicted Hamiltonians compare accurately with their DFT\ncounterparts. The method is independent of the specifics of the DFT basis or\nmaterial system used and can easily be automated and scaled for predicting\nHamiltonians of any material system of interest."
    },
    {
        "anchor": "Vacancy formation energies and migration barriers in multi-principal\n  element alloys: Multi-principal element alloys (MPEAs) continue to garner interest as\nstructural and plasma-facing materials due to their structure stability and\nincreased resistance to radiation damage. Despite sensitivity of mechanical\nbehavior to irradiation and point-defect formation, there has been scant\nattention on understanding vacancy stability and diffusion in refractory-based\nMPEAs. Using density-functional theory, we examine vacancy stability and\ndiffusion barriers in body-centered cubic (Mo0.95W0.05)0.85Ta0.10(TiZr)0.05.\nThe results in this MPEA show strong dependence on environment, originating\nfrom local lattice distortion associated with charge-transfer between\nneighboring atoms that vary with different chemical environments. We find a\ncorrelation between degree of lattice distortion and migration barrier: (Ti,\nZr) with less distortion have lower barriers, while (Mo, W) with larger\ndistortion have higher barriers, depending up local environments. Under\nirradiation, our findings suggest that (Ti, Zr) are significantly more likely\nto diffuse than (Mo, W) while Ta shows intermediate effect. As such, material\ndegradation caused by vacancy diffusion can be controlled by tuning composition\nof alloying elements to enhance creep strength at extreme operating\ntemperatures and harsh conditions.",
        "positive": "Toward the intrinsic limit of topological insulator Bi2Se3: Combining high resolution scanning tunneling microscopy and first principle\ncalculations, we identified the major native defects, in particular the Se\nvacancies and Se interstitial defects that are responsible for the bulk\nconduction and nanoscale potential fluctuation in single crystals of archetypal\ntopological insulator Bi2Se3. Here it is established that the defect\nconcentrations in Bi2Se3 are far above the thermodynamic limit, and that the\ngrowth kinetics dominate the observed defect concentrations. Furthermore,\nthrough careful control of the synthesis, our tunneling spectroscopy suggests\nthat our best samples are approaching the intrinsic limit with the Fermi level\ninside the band gap without introducing extrinsic dopants."
    },
    {
        "anchor": "Giant coercivity, resistivity upturn, and anomalous Hall effect in\n  ferrimagnetic FeTb: Despite the blooming interest, the transition-metal rare-earth ferrimagnets\nhave not been comprehensively understood in terms of their coercivity and\ntransport properties. Here, we report a systematic study of the magnetic and\ntransport properties of ferrimagnetic FeTb alloy by varying the layer thickness\nand temperature. The FeTb is tuned from the Tb-dominated regime to the\nFe-dominated regime via the layer thickness, without varying the composition.\nThe coercivity closely follows the $1/\\cos\\theta_H$ scaling (where $\\theta_H$\nis the polar angle of the external magnetic field) and increases\nquasi-exponentially upon cooling (exceeding 90 kOe at low temperatures),\nrevealing that the nature of the coercivity is the thermally-assisted domain\nwall depinning field. The resistivity exhibits a quasi-linear upturn upon\ncooling possibly due to thermal vibrations of the structure factor of the\namorphous alloy. The existing scaling laws of the anomalous Hall effect in the\nliterature break down for the amorphous FeTb that are either Fe- or\nTb-dominated. These findings should advance the understanding of the\ntransition-metal-rare-earth ferrimagnets and the associated ferrimagnetic\nphenomena in spintronics.",
        "positive": "High-throughput study of the anomalous Hall effect: Despite being known for a long time the anomalous Hall effect still attracts\nattention because of its complex origins, its connection to topology and\nbecause it serves as a useful probe of the magnetic order. Here we study the\nanomalous Hall effect using automatic high-throughput calculation scheme. We\ncalculate the intrinsic anomalous Hall effect in 2871 ferromagnetic materials.\nWe use these results to study general properties of the anomalous Hall effect\nsuch as its dependence on the strength of the spin-orbit coupling or\nmagnetization. We also examine the origin of the anomalous Hall effect in the\nmaterials with the largest effect and show that the origin of the large\nanomalous Hall effect is usually associated with symmetry protected band\ndegeneracies in the non-relativistic electronic structure, typically mirror\nsymmetry protected nodal lines. Additionally, we study the dependence of the\nanomalous Hall effect on the magnetization direction, showing that in many\nmaterials it differs significantly from the commonly assumed expression\n$\\mathbf{j}^\\text{AHE} \\sim \\mathbf{M} \\times \\mathbf{E}$."
    },
    {
        "anchor": "High-Throughput ab-initio Dilute Solute Diffusion Database: We demonstrate automated generation of diffusion databases from\nhigh-throughput density functional theory (DFT) calculations. A total of more\nthan 230 dilute solute diffusion systems in Mg, Al, Cu, Ni, Pd, and Pt host\nlattices have been determined using multi-frequency diffusion models. We apply\na correction method for solute diffusion in alloys using experimental and\nsimulated values of host self-diffusivity. We find good agreement with\nexperimental solute diffusion data, obtaining a weighted activation barrier RMS\nerror of 0.176 eV when excluding magnetic solutes in non-magnetic alloys. The\ncompiled database is the largest collection of consistently calculated\nab-initio solute diffusion data in the world.",
        "positive": "Impact of the valence band structure of Cu$_{2}$O on excitonic spectra: We present a method to calculate the exciton spectra of all direct\nsemiconductors with a complex valence band structure. The Schr\\\"odinger\nequation is solved using a complete basis set with Coulomb Sturmian functions.\nThis method also allows for the computation of oscillator strengths. Here we\napply this method to investigate the impact of the valence band structure of\ncuprous oxide $\\left(\\mathrm{Cu_{2}O}\\right)$ on the yellow exciton spectrum.\nResults differ from those in [Phys. Rev. Lett. 115, 027402 (2015)]; the\ndifferences are discussed and explained. The difference between the second and\nthird Luttinger parameter can be determined by comparisons with experiments,\nhowever, the evaluation of all three Luttinger parameters is not uniquely\npossible. Our results are consistent with band structure calculations.\nConsidering also a finite momentum $\\hbar K$ of the center of mass, we show\nthat the large $K$-dependent line splitting observed for the $1S$ exciton state\n[Phys. Rev. Lett. 91, 107401 (2003)] is not related to an exchange interaction\nbut rather to the complex valence band structure of $\\mathrm{Cu_{2}O}$."
    },
    {
        "anchor": "Plastic strain is a mixture of avalanches and quasi-reversible\n  deformations: Study of various sizes: Size-dependence of plastic flow is studied by discrete dislocation dynamical\nsimulation of systems with various numbers of interacting linear edge\ndislocations while the stress is slowly increased. Regions between avalanches\nin the individual stress curves as functions of the plastic strain were found\nnearly linear and reversible, where the plastic deformation obeys an effective\nequation of motion with a nearly linear force. For small plastic deformation,\nthe means of the stress-strain curves are power law over two decades. Here and\nfor somewhat larger plastic deformations, the mean stress-strain curves\nconverge for larger sizes, while their variances shrink, both indicating the\nexistence of a thermodynamical limit. The converging averages decrease with\nincreasing size, in accordance with size-effects from experiments. For large\nplastic deformations, where steady flow sets in, thermodynamical limit was not\nrealized in this model system.",
        "positive": "Microstructural and Mechanistic Insights into the Tension-Compression\n  Asymmetry of Rapidly Solidified Fe-Cr Alloys: A Phase Field and Strain\n  Gradient Plasticity Study: Rapid solidification in Additively Manufactured (AM) metallic materials\nresults in the development of significant microscale internal stresses, which\nare attributed to the printing induced dislocation substructures. The resulting\nbackstress due to the Geometrically Necessary Dislocations (GNDs) is\nresponsible for the observed Tension-Compression (TC) asymmetry. We propose a\ncombined Phase Field (PF)-Strain Gradient $J_2$ Plasticity (SGP) framework to\ninvestigate the TC asymmetry in such microstructures. The proposed PF model is\nan extension of Kobayashi's dendritic growth framework, modified to account for\nthe orientation-based anisotropy and multi-grain interaction effects. The SGP\nmodel has consideration for anisotropic temperature-dependent elasticity,\ndislocation strengthening, solid solution strengthening, along with GND-induced\ndirectional backstress. This model is employed to predict the solute\nsegregation, dislocation substructure and backstress development during\nsolidification and the post-solidification anisotropic mechanical properties in\nterms of the TC asymmetry of rapidly solidified Fe-Cr alloys. It is observed\nthat higher thermal gradients (and hence, cooling rates) lead to higher\nmagnitudes of solute segregation, GND density, and backstress. This also\ncorrelates with a corresponding increase in the predicted TC asymmetry. The\nresults presented in this study point to the microstructural factors, such as\ndislocation substructure and solute segregation, and mechanistic factors, such\nas backstress, which may contribute to the development of TC asymmetry in\nrapidly solidified microstructures."
    },
    {
        "anchor": "Systematic study of finite-size effects in quantum Monte Carlo\n  calculations of real metallic systems: We present a systematic and comprehensive study of finite-size effects in\ndiffusion quantum Monte Carlo calculations of metals. Several previously\nintroduced schemes for correcting finite-size errors are compared for accuracy\nand efficiency and practical improvements are introduced. In particular, we\ntest a simple but efficient method of finite-size correction based on an\naccurate combination of twist averaging and density functional theory. Our\ndiffusion quantum Monte Carlo results for lithium and aluminum, as examples of\nmetallic systems, demonstrate excellent agreement between all of the approaches\nconsidered.",
        "positive": "Cotunneling and one-dimensional localization in individual single-wall\n  carbon nanotubes: We report on the temperature dependence of the intrinsic resistance of long\nindividual disordered single-wall carbon nanotubes. The resistance grows\ndramatically as the temperature is reduced, and the functional form is\nconsistent with an activated behavior. These results are described by Coulomb\nblockade along a series of quantum dots. We occasionally observe a kink in the\nactivated behavior that reflects the change of the activation energy as the\ntemperature range is changed. This is attributed to charge hopping events\nbetween non-adjacent quantum dots, which is possible through cotunneling\nprocesses."
    },
    {
        "anchor": "Effective Medium Theory for Elastic Metamaterials in Thin Elastic Plates: An effective medium theory for resonant and non-resonant metamaterials for\nflexural waves in thin plates is presented. The theory provides closed-form\nexpressions for the effective parameters of arrangement of inclusions or\nresonators in thin plates as a function of the filling fraction of the\ninclusions, their physical properties and the frequency. It is shown that\npositive or negative effective elastic parameters are possible depending on the\nsymmetry of the resonance but, unlike it happens for bulk elastic waves, the\nresponsible for the negative mass density behaviour is the monopolar term,\nwhile the negative Young's modulus and Poisson's ratio is due to the\ncombination of monopolar and quadrupolar resonances, showing also that, at\nleast for the first order in the scattering coefficients, the dipolar resonance\nplays no role in the description of the effective medium. Several examples are\ngiven for both non-resonant and resonant effective parameters and the results\nare verified by multiple scattering theory.",
        "positive": "Conductivity of pure graphene: Theoretical approach using the\n  polarization tensor: We obtain analytic expressions for the conductivity of pristine (pure)\ngraphene in the framework of the Dirac model using the polarization tensor in\n(2+1)-dimensions defined along the real frequency axis. It is found that at\nboth zero and nonzero temperature $T$ the in-plane and out-of-plane\nconductivities of graphene are equal to each other with a high precision and\nessentially do not depend on the wave vector. At $T=0$ the conductivity of\ngraphene is real and equal to $\\sigma_0=e^2/(4\\hbar)$ up to small nonlocal\ncorrections in accordance with many authors. At some fixed $T\\neq 0$ the real\npart of the conductivity varies between zero at low frequencies $\\omega$ and\n$\\sigma_0$ for optical $\\omega$. If $\\omega$ is fixed, the conductivity varies\nbetween $\\sigma_0$ at low $T$ and zero at high $T$. The imaginary part of the\nconductivity of graphene is shown to depend on the ratio of $\\omega$ to $T$. In\naccordance to the obtained asymptotic expressions, at fixed $T$ it varies from\ninfinity at $\\omega=0$ to a negative minimum value reached at some $\\omega$,\nand then approaches to zero with further increase of $\\omega$. At fixed\n$\\omega$ the imaginary part of the conductivity varies from zero at $T=0$,\nreaches a negative minimum at some $T$ and then goes to infinity together with\n$T$. The numerical computations of both the real and imaginary parts of the\nconductivity are performed. The above results are obtained in the framework of\nquantum electrodynamics at nonzero temperature and can be generalized for\ngraphene samples with nonzero mass gap parameter and chemical potential."
    },
    {
        "anchor": "Thermal Design of Power Semiconductor Modules for Mobile Communication\n  Systems: We will describe the thermal performance of power semiconductor module, which\nconsists of hetero-junction bipolar transistors (HBTs), for mobile\ncommunication systems. We calculate the thermal resistance between the HBT\nfingers and the bottom surface of a multi-layer printed circuit board (PCB)\nusing a finite element method (FEM). We applied a steady state analysis to\nevaluate the influence of design parameters on thermal resistance of the\nmodule. We found that the thickness of GaAs substrate, the thickness of\nmulti-layer circuit board, the thermal conductivity of bonding material under\nGaAs substrate, and misalignment of thermal vias between each layer of PCB are\nthe dominant parameter in thermal resistance of the module.",
        "positive": "Recently synthesized (Zr1-xTix)2AlC (0 - x - 1) solid solutions:\n  Theoretical study of the effects of M mixing on physical properties: The effects of M atomic species mixing on the physical properties of newly\nsynthesized MAX phase (Zr1-xTix)2AlC solid solutions have been studied by means\nof density functional theory (DFT) calculations. The lattice constants in good\naccord with the experimental results, are found to decrease with Ti content.\nThe elastic constants, Cij, and the other polycrystalline elastic moduli have\nbeen calculated. The elastic constants satisfy the mechanical stability\nconditions of these solid solutions. The constants C11, C33 and C44 are found\nto increase with Ti contents up to x = 0.67, thereafter these decrease\nslightly. A reverse trend is followed by C12 and C13. The elastic moduli are\nalso found to increase up to x = 0.67, beyond which these moduli go down\nslightly. Pughs ratio and Poissons ratio both confirm the brittleness of\n(Zr1-xTix)2AlC. Different anisotropy factors revealed the anisotropic character\nof these solid solutions. A non-vanishing value of the electronic energy\ndensity of states (EDOS) at the Fermi level suggests that (Zr1-xTix)2AlC are\nmetallic in nature. A mixture of covalent, ionic and metallic bonding has been\nindicated from the electronic structure with dominant covalent bonding due to\nhybridization of Zr-4d states and C-2p states. The variation of elastic\nstiffness and elastic parameters with x is seen to be correlated with partial\nDOS (PDOS) and charge density distribution. The calculated Debye temperature\nand minimum thermal conductivity are found to increase with Ti contents, while\nmelting temperature is the highest for x = 0.67. The solid solution with x =\n0.67 shows improved mechanical and thermal properties compared to that of the\ntwo end members Zr2AlC and Ti2AlC. The study of charge transport properties of\n(Zr1-xTix)2AlC reveals the metallic nature with saturated resistivity. The\nmaximum power factor is obtained at 400 K for (Zr1-xTix)2AlC."
    },
    {
        "anchor": "Magnetization Process of the S=1/2 Heisenberg Antiferromagnet on the\n  Cairo Pentagon Lattice: We study the S=1/2 Heisenberg antiferromagnet on the Cairo pentagon lattice\nby the numerical-diagonalization method. We tune the ratio of two\nantiferromagnetic interactions coming from two kinds of inequivalent sites in\nthis lattice, examining the magnetization process of the antiferromagnet;\nparticular attention is given to one-third of the height of the saturation. We\nfind that quantum phase transition occurs at a specific ratio and that a\nmagnetization plateau appears in the vicinity of the transition. The plateau is\naccompanied by a magnetization jump on one side among the edges due to the\nspin-flop phenomenon. Which side the jump appears depends on the ratio.",
        "positive": "Achieving realistic interface kinetics in phase field models with a\n  diffusional contrast: Phase field models are powerful tools to tackle free boundary problems. For\nphase transformations involving diffusion, the evolution of the non conserved\nphase field is coupled to the evolution of the conserved diffusion field.\nIntroducing the kinetic cross coupling between these two fields [E. A. Brener,\nG. Boussinot, Phys. Rev. E {\\bf 86}, 060601(R) (2012)], we solve the\nlong-standing problem of a realistic description of interface kinetics when a\ndiffusional contrast between the phases is taken into account. Using the case\nof the solidification of a pure substance, we show how to eliminate the\ntemperature jump at the interface and to recover full equilibrium boundary\nconditions. We confirm our results by numerical simulations."
    },
    {
        "anchor": "Dislocation core properties of \u03b2-tin: A first-principles study: Dislocation core properties of tin (\\beta-Sn) were investigated using the\nsemi-discrete variational Peierls-Nabarro model (SVPN). The SVPN model, which\nconnects the continuum elasticity treatment of the long-range strain field\naround a dislocation with an approximate treatment of the dislocation core, was\nemployed to calculate various core properties, including the core energetics,\nwidths, and Peierls stresses for different dislocation structures. The role of\ncore energetics and properties on dislocation character and subsequent slip\nbehavior in \\beta-Sn was investigated. For instance, this work shows that a\nwidely spread dislocation core on the {110} plane as compared to dislocations\non the {100} and {101} planes. Physically, the narrowing or widening of the\ncore will significantly affect the mobility of dislocations as the Peierls\nstress is exponentially related to the dislocation core width in \\beta-Sn. In\ngeneral, the Peierls stress for the screw dislocation was found to be orders of\nmagnitude higher than the edge dislocation, i.e., the more the edge component\nof a mixed dislocation, the greater the dislocation mobility (lower the Peierls\nstress). The largest Peierls stress observed was 365 MPa for the dislocation on\nthe {101} plane. Furthermore, from the density plot, we see a double peak for\nthe 0deg (screw) and 30deg dislocations which suggests the dissociation of\ndislocations along these planes. Thus, for the {101} <-101> slip system, we\nobserved dislocation dissociation into three partials with metastable states.\nOverall, this work provides qualitative insights that aid in understanding the\nplastic deformation in \\beta-Sn.",
        "positive": "Ab-initio design of half-metallic fully-compensated ferrimagnets: the\n  case of Cr$_2$MnZ (Z= P, As, Sb, Bi) compounds: Electronic structure calculations from first-principles are employed to\ndesign some new half-metallic fully-compensated ferrimagnets (or as they are\nwidely known half-metallic antiferromagnets) susceptible of finding\napplications in spintronics. Cr$_2$MnZ (Z= P, As, Sb, Bi) compounds have 24\nvalence electrons per unit cell and calculations show that their total spin\nmoment is approximately zero for a wide range of lattice constants in agreement\nwith the Slater-Pauling behavior for ideal half-metals. Simultaneously, the\nspin magnetic moments of Cr and Mn atoms are antiparallel and the compounds are\nferrimagnets. Mean-field approximation is employed to estimate their Curie\ntemperature, which exceeds room temperature for the alloy with Sb. Our findings\nsuggest that Cr$_2$MnSb is the compound of choice for further experimental\ninvestigations. Contrary to the alloys mentioned above half-metallic\nantiferromagnetism is unstable in the case of the Cr$_2$FeZ (Z= Si, Ge, Sn)\nalloys."
    },
    {
        "anchor": "Spin-lattice coupling mediated giant magnetodielectricity across the\n  spin reorientation in Ca2FeCoO5: The structural, phonon, magnetic, dielectric, and magneto dielectric\nresponses of the pure bulk Brownmillerite compound Ca2FeCoO5 are reported. This\ncompound showed giant magneto dielectric response (10%-24%) induced by strong\nspin-lattice coupling across its spin reorientation transition (150-250 K). The\nrole of two Debye temperatures pertaining to differently coordinated sites in\nthe dielectric relaxations is established. The positive giant\nmagneto-dielectricity is shown to be a direct consequence of the modulations in\nthe lattice degrees of freedom through applied external field across the spin\nreorientation transition. Our study illustrates novel control of\nmagneto-dielectricity by tuning the spin reorientation transition in a material\nthat possess strong spin lattice coupling.",
        "positive": "Nonlinear dynamics of polar regions in paraelectric phase of\n  (Ba1-x,Srx)TiO3 ceramics: The dynamic dielectric nonlinearity of barium strontium titanate\n(Ba1-x,Srx)TiO3 ceramics is investigated in their paraelectric phase. With the\ngoal to contribute to the identification of the mechanisms that govern the\ndielectric nonlinearity in this family, we analyze the amplitude and the phase\nangles of the first and the third harmonics of polarization. Our study shows\nthat an interpretation of the field-dependent polarization in paraelectric\n(Ba1-x,Srx)TiO3 ceramics in terms of the Rayleigh-type dynamics is inadequate\nfor our samples and that their nonlinear response rather resembles that\nobserved in canonical relaxor Pb(Mg1/3Nb2/3)O3."
    },
    {
        "anchor": "Reconstruction of an effective magnon mean free path distribution from\n  spin Seebeck measurements in thin films: A thorough understanding of the mean-free-path (MFP) distribution of the\nenergy carriers is crucial to engineer and tune the transport properties of\nmaterials. In this context, a significant body of work has investigated the\nphonon and electron MFP distribution, however, similar studies of the magnon\nMFP distribution have not been carried out so far. In this work, we used\nthickness-dependence measurements of the longitudinal spin Seebeck (LSSE)\neffect of yttrium iron garnet films to reconstruct the cumulative distribution\nof a SSE related effective magnon MFP. By using the experimental data reported\nby Guo et al. [Phys. Rev. X 6, 031012 (2016)], we adapted the phonon MFP\nreconstruction algorithm proposed by A.J. Minnich, [Phys. Rev. Lett. 109,\n205901 (2012)] and apply it to magnons. The reconstruction showed that magnons\nwith different MFP contribute in different manner to the total LSSE and the\neffective magnon MFP distribution spreads far beyond their typical averaged\nvalues.",
        "positive": "Mechanical Ductile Detwinning in CH3NH3PbI3 Perovskite: Twin boundaries (TBs) were identified to show conflicting positive/negative\neffects on the physical properties of CH3NH3PbI3 perovskite, but their roles on\nthe mechanical properties are pending. Herein, tensile characteristics of a\nvariety of TB-dominated bicrystalline CH3NH3PbI3 perovskites are explored using\nmolecular simulations. TB-contained CH3NH3PbI3 are classified into four types\nfrom their tensile ductile detwinning characteristics. Type I is characterized\nby smooth loading flow stressstrain responses, originating from relatively\nuniform stress distribution induced gradual amorphization at TB region. Types\nII and III are represented by sudden drop of loading stresses but then distinct\nductile flow stress-strain curves, resulting from limited and large-area\namorphizations of TB-involved structures, respectively. However, Type IV is\nhighlighted by double apparent peaks in the loading curve followed by ductile\nflow response, coming from stress-concentration of\nlocalization-to-globalization at TB structure, as well as amorphization. This\nstudy provides critical insights into mechanics of CH3NH3PbI3 perovskites, and\noffers that TB engineering is a promising strategy to design mechanically\nrobust hybrid organic-inorganic perovskites-based device systems"
    },
    {
        "anchor": "The influence of thermo-electromechanical coupling on the performance of\n  lead-free BNT-type piezoelectric materials: In recent times, there have been notable advancements in haptic technology,\nparticularly in screens found on mobile phones, laptops, LED screens, and\ncontrol panels. However, it is essential to note that the progress in\nhigh-temperature haptic applications is still in the developmental phase. Due\nto its complex phase and domain structures, lead-free piezoelectric materials\nsuch as BNT-based haptic technology behave differently at high temperatures\nthan ambient conditions. Therefore, it is essential to investigate the aspects\nof thermal management and thermal stability, as temperature plays a vital role\nin the phase and domain transition of BNT material. A two-dimensional\nthermo-electromechanical model has been proposed in this study to analyze the\nthermal stability of BNT material by analyzing the impact of temperature on\neffective electromechanical properties and mechanical and electric field\nparameters. However, the thermo-electromechanical modelling of BNT ceramics\nexamines the macroscopic effects of the applied thermal field on mechanical and\nelectric field parameters as phase change and microdomain dynamics are not\nconsidered in this model. This study analyzes the impact of\nthermo-electromechanical coupling on the performance of BNT-type piezoelectric\nmaterials compared to conventional electromechanical coupling. The results\npredicted a significant improvement in piezoelectric response compared to\nelectromechanical coupling due to increased thermoelectric effect in absence of\nphase change and microdomain switching for temperature boundary conditions\nbelow depolarization temperature ($T_{d}$~200$^{\\circ}$C for pure BNT\nmaterial).",
        "positive": "A Principle of Regulating the Collective Effect of Assembling Patterns\n  in a Moderate Number of Equivalent Finite Regular Arrays of Active\n  Nanoelements due to Local Transferring Information by Pairs Hopping under\n  Synchronous Excitation: One elucidates specific findings of our recent computational study,\narxiv.org/cond-mat/0307215 with the purpose to reveal a prospect of relevant\nfeasibility research on regulating the process of assembling nano-sized\nelements into functional materials and systems. This is thought to contribute\nto solving the task of obtaining systems that being composed from nanoelements\nwould have even macroscopic sizes while preserving required stability as well\nas designing such adaptive systems. In this respect, one explains inferences\ndrawn from our findings that have shown that accomplishing the collective\neffect (CE) of assembling the active nano-elements into functional quasi two\ndimensional patterns over finite surfaces within a number, M of subsystems,\nbeing of the same type but different in details, may be regulated by changing\nthe ambient conditions. This regulation of the CE requires that the immobile\nnano-elements, arranged into regular array over the surface, are to be\nactivated due to local information transfer realized by hopping nano-sized\nelements, each represented by a pair of its ends only: sending end and the\nreceiving one; two neighbor sites of the array identify position of that pair.\nThen, the CE may be regulated by varying the number M, a common forcing factor\nand efficiency of projecting the regularity of the array onto the CE."
    },
    {
        "anchor": "From fracture to fragmentation: discrete element modeling -- Complexity\n  of crackling noise and fragmentation phenomena revealed by discrete element\n  simulations: Discrete element modelling (DEM) is one of the most efficient computational\napproaches to the fracture processes of heterogeneous materials on mesoscopic\nscales. From the dynamics of single crack propagation through the statistics of\ncrack ensembles to the rapid fragmentation of materials DEM had a substantial\ncontribution to our understanding over the past decades. Recently, the\ncombination of DEM with other simulation techniques like Finite Element\nModelling further extended the field of applicability. In this paper we briefly\nreview the motivations and basic idea behind the DEM approach to cohesive\nparticulate matter and then we give an overview of on-going developments and\napplications of the method focusing on two fields where recent success has been\nachieved. We discuss current challenges of this rapidly evolving field and\noutline possible future perspectives and debates.",
        "positive": "Kinetics of the Free-Radical Polymerization of Isobornyl Methacrylate in\n  the Presence of Polyisobutylenes of Different Molar Masses: The effect of a linear polymer dissolved in a reactive monomer on the\nkinetics of free-radical polymerization is studied. The selected system was a\nsolution of polyisobutylene (PIB) in isobornyl methacrylate (IBoMA). Ternary\nphase diagrams of PIB, IBoMA and poly(isobornyl methacrylate) (PIBoMA) were\nbuilt at 80C. They were shifted to lower conversions when increasing the molar\nmass of PIB. Different PIBs exhibiting CPC at advanced conversions were\nselected for the kinetic study performed employing differential scanning\ncalorimetry (DSC) at 80C. A simple kinetic model for free-radical\npolymerizations describing the relevant termination rate constant in terms of\nthe free-volume theory, provided a consistent fitting of the polymerization\nrates in the conversion range where the solution remained homogeneous.\nIncreasing the molar mass of PIB led to an increase in polymerization rate due\nto the decrease in free volume and the corresponding decrease of the\ntermination rate. Increasing the amount of a particular PIB in the initial\nformulation led to a less marked gel effect, explained by the smaller relative\nvariation of free volume with conversion. The dimensionless free volume of PIB\nobtained from the kinetic model was found to increase with the volume\nconcentration of chain ends, as expected. Under conditions where phase\nseparation took place at very low conversions, the overall polymerization rate\nexhibited the presence of two maxima (gel effects), representing the\npolymerization in two different phases. The first maximum was associated to the\npolymerization taking place in the phase lean in PIB and the second maximum was\nassociated to the polymerization of the monomer that was initially fractionated\nwith PIB."
    },
    {
        "anchor": "Importance of Schottky barriers for wide-bandgap thermoelectric devices: The development of thermoelectric devices faces not only the challenge of\noptimizing the Seebeck coefficient, the electrical and thermal conductivity of\nthe active material, but also further bottlenecks when going from the\nthermoelectric material to an actual device, e.g., the dopant diffusion at the\nhot contact. We show that for large bandgap thermoelectrics another aspect can\ndramatically reduce the efficiency of the device: the formation of Schottky\nbarriers. Understanding the effect, it can then be fixed rather cheaply by a\ntwo-metals contact solution.",
        "positive": "Atoms as Words: A Novel Approach to Deciphering Material Properties\n  using NLP-inspired Machine Learning on Crystallographic Information Files\n  (CIFs): In condensed matter physics and materials science, predicting material\nproperties necessitates understanding intricate many-body interactions.\nConventional methods such as density functional theory (DFT) and molecular\ndynamics (MD) often resort to simplifying approximations and are\ncomputationally expensive. Meanwhile, recent machine learning methods use\nhandcrafted descriptors for material representation which sometimes neglect\nvital crystallographic information and are often limited to single property\nprediction or a sub-class of crystal structures. In this study, we pioneer an\nunsupervised strategy, drawing inspiration from Natural Language Processing\n(NLP), to harness the underutilized potential of Crystallographic Information\nFiles (CIFs). We conceptualize atoms and atomic positions within a CIF\nsimilarly to words in textual content. Using a Word2Vec-inspired technique, we\nproduce atomic embeddings that capture intricate atomic relationships. Our\nmodel, CIFSemantics, trained on the extensive Material Project dataset, adeptly\npredicts 15 distinct material properties from the CIFs. Its performance rivals\nspecialized models, marking a significant step forward in material property\npredictions."
    },
    {
        "anchor": "Optical saturation driven by exciton confinement in molecular-chains: a\n  TDDFT study: We have identified excitonic confinement in one-dimensional molecular chains\n(i.e. polyacetylene and H$_2$) as the main driving force for the saturation of\nthe chain polarizability as a function of the number of molecular units. This\nconclusion is based on first principles time--dependent density functional\ntheory calculations performed with a new derived exchange--correlation kernel.\nThe failure of simple local and semi--local functionals is shown to be related\nto the lack of memory effects, spatial ultranonlocality, and self--interaction\ncorrections. These effects get smaller as the gap of the system reduces, in\nwhich case such simple approximations do perform better.",
        "positive": "Elastic, electronic, thermodynamic and transport properties of XOsSi\n  (X=Nb, Ta) superconductors: A first-principles exploration: A first-principles calculation has been performed to study elastic,\nelectronic, thermodynamic, transport and superconducting properties of recently\nreported osmium based two superconductors, XOsSi (X=Nb, Ta). We have calculated\nelastic constants and elastic moduli of XOsSi for the first time. The\ncalculated values of bulk, Youngs, shear moduli are reasonably larger than the\naverage value obtained from the rule of mixtures of the constituents. NbOsSi\nand TaOsSi both compounds are found to be relatively hard material, elastically\nstable and ductile in nature. The obtained directional bulk modulus and shear\nanisotropic factors indicate that both compounds have high elastic anisotropy.\nThe shear anisotropic factors show higher elastic anisotropy than the\npercentage anisotropy in these compounds. The Debye temperature and bulk\nmodulus increases with pressure but decreases with temperature as usual for\nmetals. The magnetic susceptibility of TaOsSi follow the Curie law but NaOsSi\ndo not follow due to its delocalized magnetic moment and electronic specific\nheat slightly deviates from the linear relationship with temperature. The\ncalculated band structures of XOsSi compounds show metallic nature. In both\ncases d-orbitals have the dominating contribution to the total density of\nstates. The smaller electron-phonon coupling constant implies that XOsSi (X=Nb,\nTa) are weakly coupled superconductors."
    },
    {
        "anchor": "Interface energies of (100)_{YSZ} and (111)_{YSZ} epitaxial islands on\n  (0001)_{alpha-Al_2O_3} substrates from first principles: We present an ab initio study of the interface energies of cubic\nyttria-stabilized zirconia (YSZ) epitaxial layers on a (0001)_{alpha-Al_2O_3}\nsubstrate. The interfaces are modelled using a supercell geometry and the\ncalculations are carried out in the framework of density-functional theory\n(DFT) and the local-density approximation (LDA) using the\nprojector-augmented-wave (PAW) pseudopotential approach. Our calculations\nclearly demonstrate that the (111)_{YSZ} || (0001)_{alpha-Al_2O_3} interface\nenergy is lower than that of (100)_{YSZ} || (0001)_{alpha-Al_2O_3}. This result\nis central to understanding the behaviour of YSZ thin solid film islanding on\n(0001)_{alpha-Al_2O_3} substrates, either flat or in presence of defects.",
        "positive": "Isogeometric implementation of high order microplane model for the\n  simulation of high order elasticity, softening, and localization: In this paper, a recently developed Higher Order Microplane (HOM) model for\nsoftening and localization, is implemented within a isogeometric finite element\nframework. The HOM model was derived directly from a three dimensional discrete\nparticle model and it was shown to be associated with a high order continuum\ncharacterized by independent rotation and displacement fields. Furthermore, the\nHOM model possesses two characteristic lengths: the first associated with the\nspacing of flaws in the material internal structure and related to the gradient\ncharacter of the continuum; and the second associated with the size of these\nflaws and related to the micro-polar character of the continuum. The\ndisplacement-based finite element implementation of this type of continua\nrequires $C^1$ continuity both within the elements and at the element\nboundaries. This motivated the implementation of the concept of isogeometric\nanalysis which ensures a higher degree of smoothness and continuity. NURBS\nbased isogeometric elements were implemented in a 3D setting, with both\ndisplacement and rotational degrees of freedom at each control point. The\nperformed numerical analyses demonstrate the effectiveness of the proposed HOM\nmodel implementation to ensure optimal convergence in both elastic and\nsoftening regime. Furthermore, the proposed approach allows the natural\nformulation of a localization limiter able to prevent strain localization and\nspurious mesh sensitivity known to be pathological issues for typical local\nstrain-softening constitutive equations."
    },
    {
        "anchor": "Electronic structure of pristine and K-doped solid picene:\n  Non-rigid-band change and its implication for\n  electron-intramolecular-vibration interaction: We use photoemission spectroscopy to study electronic structures of pristine\nand K-doped solid picene. The valence band spectrum of pristine picene consists\nof three main features with no state at the Fermi level (EF), while that of\nK-doped picene has three structures similar to those of pristine picene with\nnew states near EF, consistent with the semiconductor-metal transition. The\nK-induced change cannot be explained with a simple rigid-band model of pristine\npicene, but can be interpreted by molecular orbital calculations considering\nelectron-intramolecular-vibration interaction. Excellent agreement of the\nK-doped spectrum with the calculations points to importance of\nelectron-intramolecular-vibration interaction in K-doped picene.",
        "positive": "Noncontact Imaging of Ion Dynamics in Polymer Electrolytes with\n  Time-Resolved Electrostatic Force Microscopy: Ionic transport processes govern performance in many classic and emerging\ndevices, ranging from battery storage to modern mixed-conduction\nelectrochemical transistors. Here, we study local ion transport dynamics in\npolymer films using time-resolved electrostatic force microscopy (trEFM). We\nestablish a correspondence between local and macroscopic measurements using\nlocal trEFM and macroscopic electrical impedance spectroscopy (EIS). We use\npolymer films doped with lithium bis(trifluoromethane)sulfonimide (LiTFSI) as a\nmodel system where the polymer backbone has oxanorbornenedicarboximide repeat\nunits with an oligomeric ethylene oxide side chain of length n. Our results\nshow that the local polymer response measured in the time domain with trEFM\nfollows stretched exponential relaxation kinetics, consistent with the\nHavriliak-Negami relaxation we measure in the frequency-domain EIS data for\nmacroscopic samples of the same polymers. Furthermore, we show that the trEFM\nresults capture the same trends as the EIS results-changes in ion dynamics with\nincreasing temperature, increasing salt concentration, and increasing volume\nfraction of ethylene oxide side chains in the polymer matrix evolve with the\nsame trends in both measurement techniques. We conclude from this correlation\nthat trEFM data reflect, at the nanoscale, the same ionic processes probed in\nconventional EIS at the device level. Finally, as an example application for\nemerging materials syntheses, we use trEFM and infrared photoinduced force\nmicroscopy (PiFM) to image a novel diblock copolymer electrolyte for\nnext-generation solid-state energy storage applications."
    },
    {
        "anchor": "Multiscale Materials Modelling through Machine Learning: Hydrogen-Steel\n  Interaction during Deformation: This short paper presents the potential of using machine learning to predict\nmaterials behaviour in the context of hydrogen interaction with steel. Effort\nhas been made to understand the quality, and amount of data needed to get\nimproved predictions. An approach known as physics informed machine learning\nhas been adapted in a simplified way through data classification to show the\nimprovement in predictions. Proposed model eliminates the requirement to solve\ncomplex materials constitutive models and can work for any length scale, in the\npresent case it is used for single crystalline steel interacting with steel\nunder different types of loading.",
        "positive": "Defects as a factor limiting carrier mobility in WSe2: a spectroscopic\n  investigation: The electrical performance of two dimensional transitional metal\ndichalcogenides (TMDs) is strongly influenced by the amount of structural\ndefects inside. In this work, we provide an optical spectroscopic\ncharacterization approach to correlate the amount of structural defects and the\nelectrical performance of WSe2 devices. Low temperature photoluminescence (PL)\nspectra of electron beam lithography (EBL) processed WSe2 presents a clear\ndefect-induced PL emission due to excitons bound to defects, which would\nstrongly degrade the electrical performance. By adopting an e-beam-free\ntransfer-electrode technique, we are able to prepare backgated WSe2 device with\nlimited amount of defects. A maximum hole-mobility of about 200 cm2/Vs was\nachieved due to reduced scattering sources, which is the highest reported value\namong its type. This work would not only provide a versatile and nondestructive\nmethod to monitor the defects in TMDs, but also a new route to approach the\nroom temperature phonon-limited mobility in high performance TMDs devices."
    },
    {
        "anchor": "Hydrodynamic finite-size scaling of the thermal conductivity in glasses: In the past few years, the theory of thermal transport in amorphous solids\nhas been substantially extended beyond the Allen-Feldman model. The resulting\nformulation, based on the Green-Kubo linear response or the Wigner-transport\nequation, bridges this model for glasses with the traditional Boltzmann kinetic\napproach for crystals. The computational effort required by these methods\nusually scales as the cube of the number of atoms, thus severely limiting the\nsize range of computationally affordable glass models. Leveraging hydrodynamic\narguments, we show how this issue can be overcome through a simple formula to\nextrapolate a reliable estimate of the bulk thermal conductivity of glasses\nfrom finite models of moderate size. We showcase our findings for realistic\nmodels of paradigmatic glassy materials.",
        "positive": "On plastic deformation and fracture in Si films during electrochemical\n  lithiation/delithiation cycling: An in situ study of deformation, fracture, and fatigue behavior of silicon as\na lithium-ion battery electrode material is presented. Thin films (100-200 nm)\nof silicon are cycled in a half-cell configuration with lithium metal foil as\ncounter/reference electrode, with 1M lithium hexafluorophosphate in ethylene\ncarbonate, diethylene carbonate, dimethyl carbonate solution (1:1:1, wt.%) as\nelectrolyte. Stress evolution in the Si thin-film electrodes during\nelectrochemical lithiation and delithiation is measured by monitoring the\nsubstrate curvature using the multi-beam optical sensing method. The stress\nmeasurements have been corrected for contributions from residual stress arising\nfrom sputter-deposition. An indirect method for estimating the potential errors\ndue to formation of the solid-electrolyte-interphase layer and surface charge\non the stress measurements was presented. The films undergo extensive inelastic\ndeformation during lithiation and delithiation. The peak compressive stress\nduring lithiation was 1.48 GPa. The stress data along with the electron\nmicroscopy observations are used to estimate an upper bound fracture resistance\nof lithiated Si, which is approximately 9-11 J/m^2. Fracture initiation and\ncrack density evolution as a function of cycle number is also reported."
    },
    {
        "anchor": "Capping and gate control of anomalous Hall effect and hump structure in\n  ultra-thin SrRuO$_3$ films: Ferromagnetism and exotic topological structures in SrRuO$_3$ (SRO) induce\nsign-changing anomalous Hall effect (AHE). Recently, hump structures have been\nreported in the Hall resistivity of SRO thin films, especially in the\nultra-thin regime. We investigate the AHE and hump structure in the Hall\nresistivity of SRO ultra-thin films with an SrTiO$_3$ (STO) capping layer and\nionic liquid gating. STO capping results in sign changes in the AHE and\nmodulation of the hump structure. In particular, the hump structure in the Hall\nresistivity is strongly modulated and even vanishes in STO-capped 4 unit cell\n(uc) films. In addition, the conductivity of STO-capped SRO ultra-thin films is\ngreatly enhanced with restored ferromagnetism. We also performed ionic liquid\ngating to modulate the electric field at SRO/STO interface. Drastic changes in\nthe AHE and hump structure are observed with different gate voltages. Our study\nshows that the hump structure as well as the AHE can be controlled by tuning\ninversion symmetry and the electric field at the interface.",
        "positive": "BinPo: An open-source code to compute the band structure of\n  two-dimensional electron systems: We introduce BinPo, an open-source Python code to compute electronic\nproperties of two-dimensional electron systems. Its usage is focused on the\nABO$_3$ perovskite structure based systems, such as SrTiO$_3$ and KTaO$_3$,\nbecause of their increasing impact in materials community and possible\napplications in spintronic devices. BinPo has a Schr\\\"odinger-Poisson solver to\nobtain the self-consistent potential energy in a slab system. The tight binding\nslab Hamiltonian of the system is created from the transfer integrals in the\nmaximally localized Wannier functions basis, thus reaching a higher accuracy\nthan conventional tight binding methods. The band structure, energy slices, and\nother properties, along with different projections and orientations can be\ncomputed. High resolution and publishable figures of the simulations can be\ngenerated. In BinPo, priority has been given to ease-of-use, efficiency,\nreadability and modularity, therefore becoming suitable to produce reliable\nelectronic structures simulations at low computational cost. Along with the\ncode itself, we provide files from first-principles calculations, instructions\nof use and detailed examples of its wide range of capabilities. We detail the\napproaches used in the code, so that it can be further exploited and adapted to\nother problems, such as adding new materials and functionalities which can\nstrength the initial code scopes."
    },
    {
        "anchor": "Magnetic hard nanobubble: a possible magnetization structure behind the\n  bi-skyrmion: Transport of intensity equation (TIE) has been applied to process the\nsimulated and experimental images of the magnetic hard nanobubbles, which were\nacquired in the Lorentz transmission electron microscope (LTEM). Systematic\nstudies demonstrated that the processing parameter in TIE can modulate the\nfeatures of the retrieved magnetization and induce the bi-spiral structures\nwhich may be identified as the bi-skyrmions.",
        "positive": "Coherent Electrodynamic Processes in Solid Molecular Hydrogen: The many experimental puzzles of solid hydrogen, that seem to defy the\ngenerally accepted view of condensed matter, are shown to be a rather\nstraightforward consequence of a new approach to condensed matter physics, that\ntakes into account the coherent electrodynamic processes, predicted by Quantum\nElectroDynamics (QED) that have been so far overlooked. As a consequence, a\nrevision of the present view, based on electrostatic forces only, is called\nfor."
    },
    {
        "anchor": "Large Violation of the Wiedemann Franz Law in Heusler, Ferromagnetic,\n  Weyl Semimetal Co$_2$MnAl: The Wiedemann-Franz (WF) law relates the electronic component of the thermal\nconductivity to the electrical conductivity in metals through the Lorenz\nnumber. The WF law has proven to be remarkably robust, however violations have\nbeen observed in many topological materials. In this work, we report\nthermoelectric measurements conducted on Heusler, ferromagnetic, Weyl semimetal\nCo$_2$MnAl which shows a drastic, temperature dependent violation of the WF law\nbelow 300 K. We then discuss our result in the context of known physical\nexplanations for WF law violation. Both the magnitude and temperature\ndependence of the violation in Co2MnAl are extreme, indicating that there may\nbe more than one effect contributing to the violation in this system.",
        "positive": "Spectral hole lifetimes and spin population relaxation dynamics in\n  neodymium-doped yttrium orthosilicate: We present a detailed study of the lifetime of optical spectral holes due to\npopulation storage in Zeeman sublevels of Nd$^{3+}$:Y$_2$SiO$_5$. The lifetime\nis measured as a function of magnetic field strength and orientation,\ntemperature and Nd$^{3+}$ doping concentration. At the lowest temperature of 3\nK we find a general trend where the lifetime is short at low field strengths,\nthen increases to a maximum lifetime at a few hundreds of mT, and then finally\ndecays rapidly for high field strengths. This behaviour can be modelled with a\nrelaxation rate dominated by Nd$^{3+}$-Nd$^{3+}$ cross relaxation at low fields\nand spin lattice relaxation at high magnetic fields. The maximum lifetime\ndepends strongly on both the field strength and orientation, due to the\ncompetition between these processes and their different angular dependencies.\nThe cross relaxation limits the maximum lifetime for concentrations as low as\n30 ppm of Nd$^{3+}$ ions. By decreasing the concentration to less than 1 ppm we\ncould completely eliminate the cross relaxation, reaching a lifetime of 3.8 s\nat 3~K. At higher temperatures the spectral hole lifetime is limited by the\nmagnetic-field independent Raman and Orbach processes. In addition we show that\nthe cross relaxation rate can be strongly reduced by creating spectrally large\nholes of the order of the optical inhomogeneous broadening. Our results are\nimportant for the development and design of new rare-earth-ion doped crystals\nfor quantum information processing and narrow-band spectral filtering for\nbiological tissue imaging."
    },
    {
        "anchor": "A First-Principles-Based Approach to The High-Throughput Screening of\n  Corrosion-Resistant High Entropy Alloys: The design of corrosion-resistant high entropy alloys (CR-HEAs) is\nchallenging due to the alloys' virtually astrological composition space. To\nfacilitate this, efficient and reliable high-throughput exploratory approaches\nare needed. Toward this end, the current work reports a first-principles-based\napproach exploiting the correlations between work function, surface energy, and\ncorrosion resistance (i.e., work function and surface energy are, by\ndefinitions, proportional and inversely proportional to an alloy's inherent\ncorrosion resistance, respectively). Two Bayesian CALPHAD models (or databases)\nof work function and surface energy of FCC Co-Cr-Fe-Mn-Mo-Ni are assessed using\ndiscrete surface energies and work functions derived by density-functional\ntheory (DFT) calculations. The models are then used to rank different\nCo-Cr-Fe-Mn-Mo-Ni alloy compositions. It is observed that the ranked alloys\npossess chemical traits similar to previously studied corrosion-resistance\nalloys, suggesting that the proposed approach can be used to reliably screen\nHEAs with potentially good inherent corrosion resistance.",
        "positive": "In situ TEM study of twin boundary migration in sub-micron Be fibers: Deformation twinning in hexagonal crystals is often considered as a way to\npalliate the lack of independent slip systems. This mechanism might be either\nexacerbated or shut down in small-scale crystals whose mechanical behavior can\nsignificantly deviate from bulk materials. Here, we show that sub-micron\nberyllium fibers initially free of dislocation and tensile tested in-situ in a\ntransmission electron microscope (TEM) deform by a $\\{ 10\\bar{1}2 \\}$ $\\langle\n10\\bar{1}1 \\rangle$ twin thickening. The propagation speed of the twin boundary\nseems to be entirely controlled by the nucleation of twinning dislocations\ndirectly from the surface. The shear produced is in agreement with the repeated\nlateral motion of twinning dislocations. We demonstrate that the activation\nvolume ($V$) associated with the twin boundary propagation can be retrieved\nfrom the measure of the twin boundary speed as the stress decreases as in a\nclassical relaxation mechanical test. The value of $V \\approx 8.3 \\pm 3.3\n\\times 10^{-29}m^3$ is comparable to the value expected from surface\nnucleation."
    },
    {
        "anchor": "Role of hydrogen on the generation and decay of point defects in\n  amorphous silica exposed to UV laser radiation: This experimental PhD work deals with the generation and transformation\nprocesses of point defects induced by UV laser irradiation on amorphous silicon\ndioxide (silica). The investigation relies on several spectroscopic techniques\nused to probe the microscopic damage induced by UV laser on the material. The\nmost innovative approach, however, is the measurement in situ of the absorption\nsignals related to laser-induced point defects. This technique yields new\ninformation on the kinetics of defect processes, inaccessible to previous works\nbased only on stationary measurements of laser-induced damage. The main result\nis to show that a major damage mechanism of silica under 4.7eV laser radiation\nis the generation of E' centers (silicon dangling bond defects) by photolysis\nof pre-existing Si-H bonds. This process occurs by two-photon absorption of\nlaser light, and the produced E' centers are unstable in a wide temperature\nrange: in fact, rupture of Si-H produces hydrogen atoms H together with E';\nhence, H atoms dimerize in H_2, which diffuses in the glass and reacts back\nwith the E' centers causing their decay. The generation and decay kinetics of\nlaser-induced E' centers are quantitatively modelled by considering the\ncompetition between the laser-induced breakage of Si-H and the concurrent\nreaction between E' and H_2. The latter reaction is studied in detail at\nseveral temperatures: some of its features are found to be affected by the\ndisorder of the glass matrix; moreover, its kinetics is found to be\nactivation-limited rather than diffusion-limited, contrary to what is usually\nfound for the reactions of diffusing species with point defects.",
        "positive": "Monolithic Photoelectrochemical Device for 19% Direct Water Splitting: Recent rapid progress in efficiencies for solar water splitting by\nphotoelectrochemical devices has enhanced its prospects to enable storable\nrenewable energy. Efficient solar fuel generators all use tandem photoelectrode\nstructures, and advanced integrated devices incorporate corrosion protection\nlayers as well as heterogeneous catalysts. Realization of near thermodynamic\nlimiting performance requires tailoring the energy band structure of the\nphotoelectrode and also the optical and electronic properties of the surface\nlayers exposed to the electrolyte. Here, we report a monolithic device\narchitecture that exhibits reduced surface reflectivity in conjunction with\nmetallic Rh nanoparticle catalyst layers that minimize parasitic light\nabsorption. Additionally, the anatase TiO2 protection layer on the photocathode\ncreates a favorable internal band alignment for hydrogen evolution. An initial\nsolar-to-hydrogen efficiency of 19.3 % is obtained in acidic electrolyte and an\nefficiency of 18.5 % is achieved at neutral pH condition (under simulated\nsunlight)."
    },
    {
        "anchor": "Structural and magnetic properties of lightly doped M-type hexaferrites: Vanadium substituted SrM hexaferrites (SrFe12-xVxO19 with x = 0.2, 0.4) and\nEu-substituted BaM hexaferrite (Ba0.8Eu0.2Fe12O19) were prepared by high energy\nball milling and sintering at 1200{\\deg} C. X-ray diffraction measurements\nrevealed that the V-substituted SrM samples exhibited phase separation\nresulting in the coexistence of the pure SrM magnetic phase with nonmagnetic\nSr3(VO4)2 vanadate and {\\alpha}-Fe2O3 iron oxide phase. Also, the\nEu-substituted BaM hexaferrite revealed the formation of the pure BaM phase\ncoexisting with {\\alpha}-Fe2O3 secondary phase, and Eu-garnet minor phase.\nAlthough the magnetic properties of the samples deteriorated with respect to\npure hexaferrite properties, the magnetic parameters of the substituted samples\nwere found to be of potential importance for practical applications. Further,\nthe results of the study suggest methods for the preparation of high quality\nSrM hexaferrites, and hexaferrite/garnet composites.",
        "positive": "Hybrid resonant phenomenon in a metamaterial structure with integrated\n  resonant magnetic material: We explore the hybridization of fundamental material resonances with the\nartificial resonances of metamaterials. A hybrid structure is presented in the\nwaveguide environment that consists of a resonant magnetic material with a\ncharacteristic tuneable gyromagnetic response that is integrated into a\ncomplementary split ring resonator (CSRR) metamaterial structure. The combined\nstructure exhibits a distinct hybrid resonance in which each natural resonance\nof the CSRR is split into a lower and upper resonance that straddle the\nfrequency for which the magnetic material's permeability is zero. We provide an\nanalytical understanding of this hybrid resonance and define an effective\nmedium theory for the combined structure that demonstrates good agreement with\nnumerical electromagnetic simulations. The designed structure demonstrates the\npotential for using a ferrimagnetic or ferromagnetic material as a means of\ncreating a tunable metamaterial structure."
    },
    {
        "anchor": "Host isotope mass effects on the hyperfine interaction of group-V donors\n  in silicon: The effects of host isotope mass on the hyperfine interaction of group-V\ndonors in silicon are revealed by pulsed electron nuclear double resonance\n(ENDOR) spectroscopy of isotopically engineered Si single crystals. Each of the\nhyperfine-split P-31, As-75, Sb-121, Sb-123, and Bi-209 ENDOR lines splits\nfurther into multiple components, whose relative intensities accurately match\nthe statistical likelihood of the nine possible average Si masses in the four\nnearest-neighbor sites due to random occupation by the three stable isotopes\nSi-28, Si-29, and Si-30. Further investigation with P-31 donors shows that the\nresolved ENDOR components shift linearly with the bulk-averaged Si mass.",
        "positive": "Effect of the techniqie of drawing with shear on the structure and the\n  properties of low-carbon wires: The technology of drawing with shear is developed. It allows increasing\ntechnological plasticity of low carbon steel without heat treatment. It is\nfound that the use of experimental technology can improve mechanical properties\nof wire samples with the diameter reduced during drawing: the relative\nreduction of the wire decreases slightly and remains at high level compared\nwith the classical technology, where the relative reduction in the course of\ndrawing drops more than twice. It is shown that the use of experimental\ntechnology allows varying the size of a ferrite grain (increase or decrease)\ncompared with the classical technology, where increasing of deformation degree\nresults in grain reduction. Furthermore, the experimental technology allows\nreducing the number of pores in a wire of small diameter. To prevent heating of\nthe wire and the drawing dies, it is proposed to use experimental drawing\nthrough two experimental dies with shear separated by an ordinary die. As a\nresult, the workability of the process will be enhanced and the efforts of\ndrawing will be reduced."
    },
    {
        "anchor": "Fabrication of Hollow AlAu2 Nanoparticles by Solid State Dewetting and\n  Oxidation of Al on Sapphire Substrate: The Al-Au binary diffusion couple is a classic example of the system\nexhibiting Kirkendall voiding during interdiffusion. We demonstrate that this\neffect, which is a major reason for failures of the wire bonds in\nmicroelectronics, can be utilized for producing hollow AlAu2 nanoparticles\nattached to sapphire substrate. To this end, we produced the core-shell Al-Au\nnanoparticles by performing a solid state dewetting treatment of Al thin film\ndeposited on sapphire substrate, followed by the deposition of thin Au layer on\nthe top of dewetted sample. Annealing of the core-shell nanoparticles in air\nresulted in outdiffusion of Al from the particles, formation of pores, and\ngrowth of the AlAu2 intermetallic phase in the particles. We demonstrated that\nthe driving force for hollowing is the oxidation reaction of the Al atoms at\nthe Au-sapphire interface, leading to the homoepitaxial growth of newly formed\nalumina at the interface. We developed a kinetic model of hollowing controlled\nby diffusion of oxygen through the Au thin film, and estimated the solubility\nof oxygen in solid Au. Our work demonstrates that the core-shell nanoparticles\nattached to the substrate can be hollowed by the Kirkendall effect in the thin\nfilm spatially separated from the particles.",
        "positive": "Making a case for femto- phono- magnetism with FePt: In the field of femtomagnetism magnetic matter is controlled by ultrafast\nlaser pulses; here we show that coupling phonon excitations of the nuclei to\nspin and charge leads to femto-phono-magnetism, a powerful route to control\nmagnetic order at ultrafast times. With state-of-the-art theoretical\nsimulations of coupled spin-, charge-, and lattice-dynamics we identify strong\nnon-adiabatic spin-phonon coupled modes that dominate early time spin dynamics.\nActivating these phonon modes we show leads to an additional (up to 40\\% extra)\nloss of moment in FePt occurring within 40 femtoseconds of the pump laser\npulse. Underpinning this enhanced ultrafast loss of spin moment we identify a\nphysical mechanism in which minority spin-current drives an enhanced inter-site\nminority charge transfer, in turn promoting increased on-site spin flips. Our\nfinding demonstrates that the nuclear system, often assumed to play only the\nrole of an energy sink aiding long time re-magnetisation of the spin system,\ncan play a profound role in controlling femtosecond spin-dynamics in materials."
    },
    {
        "anchor": "Acoustic Emission of Growing Microcracks in Vibration-Loaded Material: We propose mechanism describing an acoustic emission by growing microcracks\nin the material under external cycled load. We use the theoretical approach\nbased on Huygens principle for elastic solid con-tinuum with an account for\ndislocation creep in the zone of abrasive action. We show that the acoustic\nemission is anisotropic and its main direction depends not only on the\neffective length of microcrack but also on dynamics of dislocation structure\nand on diffusion processes in Kottrell zone which give rise to microcracks.",
        "positive": "A First Principle Study on Iron Substituted LiNi(BO3) to use as Cathode\n  Material for Li-ion Batteries: In this work, the structural stability and the electronic properties of\nLiNiBO 3 and LiFe x Ni (1-x) BO 3 are studied using first principle\ncalculations based on density functional theory. The calculated structural\nparameters are in good agreement with the available theoretical data. The most\nstable phases of the Fe substituted systems are predicted from the formation\nenergy hull generated using the cluster expansion method. The 66% of Fe\nsubstitution at the Ni site gives the most stable structure among all the Fe\nsubstituted systems. The bonding mechanisms of the considered systems are\ndiscussed based on the density of states (DOS) and charge density plot. The\ndetailed analysis of the stability, electronic structure, and the bonding\nmechanisms suggests that the systems can be a promising cathode material for Li\nion battery applications."
    },
    {
        "anchor": "Systematic vertex corrections through iterative solution of Hedin's\n  equations beyond the GW approximation: We present a general procedure for obtaining progressively more accurate\nfunctional expressions for the electron self-energy by iterative solution of\nHedin's coupled equations. The iterative process starting from Hartree theory,\nwhich gives rise to the GW approximation, is continued further, and an explicit\nformula for the vertex function from the second full cycle is given. Calculated\nexcitation energies for a Hubbard Hamiltonian demonstrate the convergence of\nthe iterative process and provide further strong justification for the GW\napproximation.",
        "positive": "Nanoscale heat transfer at contact between a hot tip and a substrate: Hot tips are used either for characterizing nanostructures by using scanning\nthermal microscopes or for local heating to assist data writing. The tip-sample\nthermal interaction involves conduction at solid-solid contact as well as\nconduction through the ambient gas and through the water meniscus. We analyze\nthose three heat transfer modes with experimental data and modeling. We\nconclude that the three modes contribute in a similar manner to the thermal\ncontact conductance but they have distinct contact radii ranging from 30 nm to\n1 micron. We also show that any scanning thermal microscope has a 1-3 microns\nresolution when used in ambient air."
    },
    {
        "anchor": "Anodic TiO2 nanotube layers: why does self-organized growth occur - A\n  mini review: The present review gives an overview of the highlights of more than 10 years\nof research on synthesis and applications of ordered oxide structures (nanotube\nlayers, hexagonal pore arrangements) that are formed by self-organizing\nanodization of metals. In particular we address the questions after the\ncritical factors that lead to the spectacular self-ordering during the growth\nof anodic oxides that finally yield morphologies such as highly ordered TiO2\nnanotube arrays and similar structures. Why are tubes and pores formed - what\nare the key parameters controlling these processes?",
        "positive": "Origin of the abnormal diffusion of transition metal in rutile: Diffusion of dopants in rutile is the fundamental process that determines the\nperformance of many devices in which rutile is used. The diffusion behavior is\nknown to be highly sample-dependent, but the reasons for this are less well\nunderstood. Here, rutile is studied by using first-principles calculations, in\norder to unravel the microscopic origins of the diverse diffusion behaviors for\ndifferent doping elements. Anomalous diffusion behavior in the open channel\nalong [001] direction is found: larger atoms include Sc and Zr have lower\nenergy barrier for diffusion via interstitial mechanism, apparently\ncontradicting their known slow diffusion rate. To resolve this, we present an\nalternate model for the overall diffusion rate of the large-size dopants in\nrutile, showing that parallel to the [001] channel, it is limited by the\nformation of the interstitial states, whereas in the direction perpendicular to\n[001], it proceeds via a kick-out mechanism. By contrast, Co and Ni, prefer to\nstay in the interstitial site of rutile, and have conventional diffusion with a\nvery small migration barrier in the [001] channel. This leads to highly\nanisotropic and fast diffusion. The diffusion mechanisms found in the present\nstudy can explain the diffusion data measured by experiments, and these\nfindings provide novel understanding for the classic diffusion topic."
    },
    {
        "anchor": "Ab-initio semi-classical electronic transport in ZnSe: The role of\n  inelastic scattering mechanisms: We present a detailed ab-initio study of semi-classical transport in n-ZnSe\nusing Rode's iterative method. Inclusion of ionized impurity, piezoelectric,\nacoustic deformation and polar optical phonon scattering and their relative\nimportance at low and room temperature for various n-ZnSe samples are discussed\nin depth. We have clearly noted that inelastic polar optical phonon scattering\nis the most dominant scattering mechanism over most of the temperature region.\nOur results are in good agreement with the experimental data for the mobility\nand conductivity obtained at different doping concentrations over a wider range\nof temperatures. Also we compare these results with the ones obtained with\nrelaxation time approximation (RTA) which clearly demonstrate the superiority\nof the iterative method over RTA.",
        "positive": "Highly anisotropic magnetic states of Co dimers bound to\n  graphene-vacancies: The adsorption behavior and the magnetic states of cobalt atoms and dimers on\nsingle vacancies in a graphene sheet are investigated by means of relativistic\ndensity functional calculations. It is found that local magnetic moments are\nformed in both cases, despite strong chemical binding. Of particular interest\nare kinetically stable isomers with two cobalt atoms attached to the same side\nof the graphene sheet. Magnetic bi-stability with an anisotropy barrier of\nabout 50 meV is possible in this geometry. The feasibility of its preparation\nis discussed."
    },
    {
        "anchor": "Angle-Dependent Spin-Wave Resonance Spectroscopy of (Ga,Mn)As Films: A modeling approach for standing spin-wave resonances based on a\nfinite-difference formulation of the Landau-Lifshitz-Gilbert equation is\npresented. In contrast to a previous study [Bihler et al., Phys. Rev. B 79,\n045205 (2009)], this formalism accounts for elliptical magnetization precession\nand magnetic properties arbitrarily varying across the layer thickness,\nincluding the magnetic anisotropy parameters, the exchange stiffness, the\nGilbert damping, and the saturation magnetization. To demonstrate the\nusefulness of our modeling approach, we experimentally study a set of (Ga,Mn)As\nsamples grown by low-temperature molecular-beam epitaxy by means of\nelectrochemical capacitance-voltage measurements and angle-dependent standing\nspin-wave resonance spectroscopy. By applying our modeling approach, the angle\ndependence of the spin-wave resonance data can be reproduced in a simulation\nwith one set of simulation parameters for all external field orientations. We\nfind that the approximately linear gradient in the out-of-plane magnetic\nanisotropy is related to a linear gradient in the hole concentrations of the\nsamples.",
        "positive": "Phase-field modelling of solute trapping during rapid solidification of\n  a Si-As alloy: The effect of nonequilibrium solute trapping by a growing solid under rapid\nsolidification conditions is studied using a phase-field model. Considering a\ncontinuous steady-state concentration profile across the diffuse solid-liquid\ninterface, a new definition of the nonequilibrium partition coefficient in the\nphase-field context is introduced. This definition leads, in particular for\nhigh growth velocities, to a better description of the available experimental\ndata in comparison with other diffuse interface and sharp-interface\npredictions."
    },
    {
        "anchor": "Photoferroelectric and Photopiezoelectric Properties of Organometal\n  Halide Perovskites: Piezoelectrics play a critical role in various applications. The permanent\ndipole associated with the molecular cations in organometal-halide perovskites\n(OMHPs) may lead to spontaneous polarization and thus piezoelectricity. Here,\nwe explore the piezoelectric properties of OMHPs with density functional\ntheory. We find that the piezoelectric coefficient depends sensitively on the\nmolecular ordering, and that the experimentally observed light-enhanced\npiezoelectricity is due to to a non-polar to polar structural transition. By\ncomparing OMHPs with different atomic substitutions in the $ABX_3$\narchitecture, we find that the displacement of the $B$-site cation contributes\nto nearly all the piezoelectric response, and that the competition between\n$A$-$X$ hydrogen bond and $B$-$X$ metal-halide bond in OMHPs controls the\npiezoelectric properties. These results highlight the potential of the OMHP\narchitecture for designing new functional photoferroelectrics and\nphotopiezoelectrics.",
        "positive": "Transient absorption and photocurrent microscopy show hot electron\n  supercollisions describe the rate-limiting relaxation step in graphene: Using transient absorption (TA) microscopy as a hot electron thermometer we\nshow disorder-assisted acoustic-phonon supercollisions (SCs) best describes the\nrate-limiting relaxation step in graphene over a wide range of lattice\ntemperatures ($T_l=$5-300 K), Fermi energies ($E_F=\\pm0.35$ eV), and optical\nprobe energies (~0.3 - 1.1 eV). Comparison with simultaneously collected\ntransient photocurrent, an independent hot electron thermometer, confirms the\nrate-limiting optical and electrical response in graphene are best described by\nthe SC-heat dissipation rate model, $H=A(T^3_e- T^3_l)$. Our data further shows\nthe electron cooling rate in substrate supported graphene is twice as fast as\nin suspended graphene sheets, consistent with SC-model prediction for disorder."
    },
    {
        "anchor": "Liquid structure changes of Bi under different melt states: This paper is focused on the relationship between solidification and melt\nsates. An abnormal change which takes place at 744 C from 84 to 120 min\nindicated a liquid-liquid structure transition in pure Bi melt. Based on\nliquid-liquid structure transition, experiments of pure Bi were carried out.\nCooling from different melt states, the solidification behaviors and structures\nchanged a lot, such as undercooling, solidification time, grain sizes and the\nnumber of twins and pedestal sits. Especially, as a semi-metal, a liquid-liquid\nstructure transition greatly increases the metallicity of Bi, and during the\nsolidification Bi turned from smooth to coarse solid/ liquid interface.",
        "positive": "Emergence of photoswitchable states in a graphene-azobenzene-Au platform: The perfect transmission of charge carriers through potential barriers in\ngraphene (Klein tunneling) is a direct consequence of the Dirac equation that\ngoverns the low-energy carrier dynamics. As a result, localized states do not\nexist in unpatterned graphene, but quasi-bound states \\emph{can} occur for\npotentials with closed integrable dynamics. Here, we report the observation of\nresonance states in photo-switchable self-assembled molecular(SAM)-graphene\nhybrid. Conductive AFM measurements performed at room temperature reveal strong\ncurrent resonances, the strength of which can be reversibly gated \\textit{on-}\nand \\textit{off-} by optically switching the molecular conformation of the\nmSAM. Comparisons of the voltage separation between current resonances ($\\sim\n70$--$120$ mV) with solutions of the Dirac equation indicate that the radius of\nthe gating potential is $\\sim 7 \\pm 2$ nm with a strength $\\geq 0.5$ eV. Our\nresults and methods might provide a route toward \\emph{optically programmable}\ncarrier dynamics and transport in graphene nano-materials."
    },
    {
        "anchor": "Atomic origin for hydrogenation promoted bulk oxygen vacancies removal\n  in vanadium dioxide: Oxygen vacancies (VO), a common type of point defects in metal oxides\nmaterials, play important roles on the physical and chemical properties. To\nobtain stoichiometric oxide crystal, the pre-existing VO is always removed via\ncareful post-annealing treatment at high temperature in air or oxygen\natmosphere. However, the annealing conditions is difficult to control and the\nremoval of VO in bulk phase is restrained due to high energy barrier of VO\nmigration. Here, we selected VO2 crystal film as the model system and developed\nan alternative annealing treatment aided by controllable hydrogen doping, which\ncan realizes effective removal of VO defects in VO2-{\\delta} crystal at lower\ntemperature. This finding is attributed to the hydrogenation accelerated oxygen\nvacancies recovery in VO2-{\\delta} crystal. Theoretical calculations revealed\nthat the H-doping induced electrons are prone to accumulate around the oxygen\ndefects in VO2-{\\delta} film, which facilitates the diffusion of VO and thus\nmakes it easier to be removed. The methodology is expected to be applied to\nother metal oxides for oxygen-related point defects control.",
        "positive": "Giant electrocaloric effect in thin film Pb Zr_0.95 Ti_0.05 O_3: An applied electric field can reversibly change the temperature of an\nelectrocaloric material under adiabatic conditions, and the effect is strongest\nnear phase transitions. This phenomenon has been largely ignored because only\nsmall effects (0.003 K V^-1) have been seen in bulk samples such as\nPb0.99Nb0.02(Zr0.75Sn0.20Ti0.05)0.98O3 and there is no consensus on macroscopic\nmodels. Here we demonstrate a giant electrocaloric effect (0.48 K V^-1) in 300\nnm sol-gel PbZr0.95Ti0.05O3 films near the ferroelectric Curie temperature of\n222oC. We also discuss a solid state device concept for electrical\nrefrigeration that has the capacity to outperform Peltier or magnetocaloric\ncoolers. Our results resolve the controversy surrounding macroscopic models of\nthe electrocaloric effect and may inspire ab initio calculations of\nelectrocaloric parameters and thus a targeted search for new materials."
    },
    {
        "anchor": "Cavity-Enhanced Raman Scattering from 2D Hybrid Perovskites: Two-dimensional (2D) hybrid organic-inorganic perovskites (HOIPs) are\npromising candidates for optoelectronic applications due to their efficient\nlight emission properties, and strong dielectric confinement effects. Raman\nspectroscopy is a versatile, non-contact and often non-destructive technique,\nwidely used to characterize crystalline materials. However, the inherently weak\nphonon scattering, strong background, and complex nature of the Raman signals\nfrom HOIPs present challenges in obtaining reliable signals. Further, the\nfragile nature of the 2D HOIP crystals results in rapid degradation upon\nexposure to heat, light and moisture, which presents further difficulty in\nenhancing Raman scattered photon signals. Herein, we report a novel approach to\nenhance the weak Raman scattering signals in Ruddlesden-Popper (RP) phase HOIPs\nby introducing an open-cavity comprising HOIP crystals on a gold substrate. We\nobserve 15x enhancement of the Raman signals due to the Purcell effect inside\nthe high-index HOIP crystals. Our simple approach can be extended to enhance\nthe study of phonon scattering in other HOIP and van der Waals layered\ncrystals.",
        "positive": "Photonics of shungite quantum dots: Shungite quantum dots are associated with nanosize fragments of reduced\ngraphene oxide similarly to synthetic graphene quantum dots thus forming a\ncommon class of GQDs. Colloidal dispersions of powdered shungite in water,\ncarbon tetrachloride, and toluene form the ground for the GQD photonic\npeculiarities manifestation. Morphological study shows a steady trend of GQDs\nto form fractals and a drastic change in the colloids fractal structure caused\nby solvent was reliably established. Spectral study reveals a dual character of\nemitting centers: individual GQDs are responsible for the spectra position\nwhile fractal structure of GQD colloids provides high broadening of the spectra\ndue to structural inhomogeneity of the colloidal dispersions and a peculiar\ndependence on excitation wavelength. For the first time, photoluminescence\nspectra of individual GQDs were observed in frozen toluene dispersions which\npave the way for a theoretical treatment of GQD photonics."
    },
    {
        "anchor": "Electrical transport and optical studies of ferromagnetic Cobalt doped\n  ZnO nanoparticles exhibiting a metal-insulator transition: The observed correlation of oxygen vacancies and room temperature\nferromagnetic ordering in Co doped ZnO1-o nanoparticles reported earlier (Naeem\net al Nanotechnology 17, 2675-2680) has been further explored by transport and\noptical measurements. In these particles room temperature ferromagnetic\nordering had been observed to occur only after annealing in forming gas. In the\ncurrent work the optical properties have been studied by diffuse reflection\nspectroscopy in the UV-Vis region and the band gap of the Co doped compositions\nhas been found to decrease with Co addition. Reflections minima are observed at\nthe energies characteristic of Co+2 d-d (tethrahedral symmetry) crystal field\ntransitions, further establishing the presence of Co in substitutional sites.\nElectrical transport measurements on palletized samples of the nanoparticles\nshow that the effect of a forming gas is to strongly decrease the resistivity\nwith increasing Co concentration. For the air annealed and non-ferromagnetic\nsamples the variation in the resistivity as a function of Co content are\nopposite to those observed in the particles prepared in forming gas. The\nferromagnetic samples exhibit an apparent change from insulator to metal with\nincreasing temperatures for T>380K and this change becomes more pronounced with\nincreasing Co content. The magnetic and resistive behaviors are correlated by\nconsidering the model by Calderon et al [M. J. Calderon and S. D. Sarma, Annals\nof Physics 2007 (Accepted doi: 10.1016/j.aop.2007.01.010] where the\nferromagnetism changes from being mediated by polarons in the low temperature\ninsulating region to being mediated by the carriers released from the weakly\nbound states in the higher temperature metallic region.",
        "positive": "Electronic Structures of Fe$_{3-x}V$_x$Si Probed by Photoemission\n  Spectroscopy: The electronic structures of the Heusler type compounds Fe$_{3-x}V$_x$Si in\nthe concentration range between x = 0 and x = 1 have been probed by\nphotoemission spectroscopy (PES). The observed shift of Si 2p core- level and\nthe main valence band structres indicate a chemical potential shift to higher\nenergy with increasing x. It is also clarified that the density of state at\nFermi edge is owing to the collaboration of V 3d and Fe 3d derived states.\nBesides the decrease of the spectral intensity near Fermi edge with increasing\nx suggests the formation of pseudo gap at large x."
    },
    {
        "anchor": "Growth Kinetics of Ion Beam Sputtered Al-thin films by Dynamic Scaling\n  Theory: This paper reports the study of growth kinetics of ion beam sputtered\naluminum thin films. Dynamic scaling theory was used to derive the kinetics\nfrom AFM measurements. AFM imaging revealed that surface incorporates\ndistinctly different morphologies. Variation in deposition times resulted in\nsuch distinctiveness. The growth governing static (alpha) as well as dynamic\n(beta) scaling exponents have been determined. The exponent (alpha) decreased\nas the deposition time increased from 3 to 15 minutes. Consequently, the\ninterfacial width (xi) also decreased with critical length (Lc), accompanied\nwith an increase in surface roughness. Surface diffusion becomes a major\nsurface roughening phenomenon that occurs during deposition carried out over a\nshort period of 3 minutes. Extension of deposition time to 15 minutes brought\nin bulk diffusion process to dominate which eventually led to smoothening of a\ncontinuous film.",
        "positive": "On continuum modeling of sputter erosion under normal incidence:\n  interplay between nonlocality and nonlinearity: Under specific experimental circumstances, sputter erosion on semiconductor\nmaterials exhibits highly ordered hexagonal dot-like nanostructures. In a\nrecent attempt to theoretically understand this pattern forming process, Facsko\net al. [Phys. Rev. B 69, 153412 (2004)] suggested a nonlocal, damped\nKuramoto-Sivashinsky equation as a potential candidate for an adequate\ncontinuum model of this self-organizing process. In this study we theoretically\ninvestigate this proposal by (i) formally deriving such a nonlocal equation as\nminimal model from balance considerations, (ii) showing that it can be exactly\nmapped to a local, damped Kuramoto-Sivashinsky equation, and (iii) inspecting\nthe consequences of the resulting non-stationary erosion dynamics."
    },
    {
        "anchor": "Photocatalytic acetaldehyde oxidation in air using spacious TiO2 films\n  prepared by atomic layer deposition on supported carbonaceous sacrificial\n  templates: Supported carbon nanosheets and carbon nanotubes served as sacrificial\ntemplates for preparing spacious TiO2 photocatalytic thin films. Amorphous TiO2\nwas deposited conformally on the carbonaceous template material by atomic layer\ndeposition (ALD). Upon calcination at 550{\\deg}C, the carbon template was\noxidatively removed and the as-deposited continuous amorphous TiO2 layers\ntransformed into interlinked anatase nanoparticles with an overall morphology\ncommensurate to the original template structure. The effect of type of\ntemplate, number of ALD cycles and gas residence time of pollutant on the\nphotocatalytic activity, as well as the stability of the photocatalytic\nperformance of these thin films was investigated. The TiO2 films exhibited\nexcellent photocatalytic activity towards photocatalytic degradation of\nacetaldehyde in air as a model reaction for photocatalytic indoor air pollution\nabatement. Optimized films outperformed a reference film of commercial PC500.",
        "positive": "Auger Recombination Lifetime Scaling for Type-I and Quasi-Type-II\n  Core/Shell Quantum Dots: Having already achieved near-unity quantum yields, with promising properties\nfor light-emitting diode, lasing, and charge separation applications, colloidal\ncore/shell quantum dots have great technological potential. The shell thickness\nand band alignment of the shell and core materials are known to influence the\nefficiency of these devices. In many such applications, a key to improving the\nefficiency requires a deep understanding of multiexcitonic states. Herein, we\nelucidate the shell thickness and band alignment dependencies of the biexciton\nAuger recombination lifetime for quasi-type-II CdSe/CdS and type-I CdSe/ZnS\ncore/shell quantum dots. We find that the biexciton Auger recombination\nlifetime increases with the total nanocrystal volume for quasi-type-II CdSe/CdS\ncore/shell quantum dots and is independent of the shell thickness for type-I\nCdSe/ZnS core/shell quantum dots. In order to perform these calculations and\ncompute Auger recombination lifetimes, we developed a low-scaling approach\nbased on the stochastic resolution of identity. The numerical approach provided\na framework to study the scaling of the biexciton Auger recombination lifetimes\nin terms of the shell thickness dependencies of the exciton radii, Coulomb\ncouplings, and density of final states in quasi-type-II CdSe/CdS and type-I\nCdSe/ZnS core/shell quantum dots."
    },
    {
        "anchor": "Exchange bias in van der Waals MnBi$_2$Te$_4$/Cr$_2$Ge$_2$Te$_6$\n  heterostructure: The layered van der Waals (vdW) material MnBi$_2$Te$_4$ is an intrinsic\nmagnetic topological insulator with various topological phases such as quantum\nanomalous Hall effect (QAHE) and axion states. However, both the zero-field and\nhigh-temperature QAHE are not easy to realize. It is theoretically proposed\nthat the exchange bias can be introduced in the MnBi2Te4/ferromagnetic (FM)\ninsulator heterostructures and thus opens the surface states gap, making it\neasier to realize the zero-field or high-temperature QAHE. Here we report the\nelectrically tunable exchange bias in the van der Waals\nMnBi$_2$Te$_4$/Cr$_2$Ge$_2$Te$_6$ heterostructure. The exchange bias emerges\nover a critical magnetic field and reaches the maximum value near the magnetic\nband gap. Moreover, the exchange bias was experienced by the antiferromagnetic\n(AFM) MnBi$_2$Te$_4$ layer rather than the FM layer. Such van der Waals\nheterostructure provides a promising platform to study the novel exchange bias\neffect and explore the possible high-temperature QAHE.",
        "positive": "Dehydrogenation through the pressure-induced polymerization processes of\n  phosphine: PH3 is studied to understand the superconducting transition and responsible\nstoichiometry under high pressure by means of Raman, IR, and x-ray diffraction\n(XRD) measurements, and theoretical calculations. It is found PH3 is stable up\nto about 8 GPa and then starts to dehydrogenate through two dimerization\nprocesses at room temperature as pressure up to 25 GPa. Two resulting\nphosphorus hydrides, P2H4 and P4H6, are verified experimentally and can be\nrecovered to ambient pressure. On further compression above 35 GPa, P4H6\ndirectly decomposes into elemental phosphorus. The superconductivity transition\ntemperatures of P4H6 at 100 and 200 GPa have been predicted to be 13 and 67 K\nin agreement with reported results, suggesting it might responsible for the\nsuperconductivity at higher pressures. Our results clearly show that P2H4 and\nP4H6 are only stable P-H compounds between PH3 and elemental phosphorus,\nshedding light on the superconducting mechanism."
    },
    {
        "anchor": "Spin transport and spin conversion in compound semiconductor with\n  non-negligible spin-orbit interaction: A quantitative investigation of spin-pumping-induced spin-transport in n-GaAs\nwas conducted at room temperature (RT). GaAs has a non-negligible spin orbit\ninteraction, so that electromotive force due to the inverse spin Hall effect\n(ISHE) of GaAs contributed to the electromotive force detected with a platinum\n(Pt) spin detector. The electromotive force detected by the Pt spin detector\nhad opposite polarity to that measured with a Ni80Fe20/GaAs bilayer due to the\nopposite direction of spin current flow, which demonstrates successful spin\ntransport in the n-GaAs channel. A two-dimensional spin-diffusion model that\nconsiders the ISHE in the n-GaAs channel reveals an accurate spin diffusion\nlength of t_s = 1.09 um in n-GaAs (NSi = 4x10^16 cm-3) at RT, which is\napproximately half that estimated by the conventional model.",
        "positive": "In-situ real-space imaging of crystal surface reconstruction dynamics\n  via electron microscopy: Crystal surfaces are sensitive to the surrounding environment, where atoms\nleft with broken bonds reconstruct to minimize surface energy. In many cases,\nthe surface can exhibit chemical properties unique from the bulk. These\ndifferences are important as they control reactions and mediate thin film\ngrowth. This is particularly true for complex oxides where certain terminating\ncrystal planes are polar and have a net dipole moment. For polar terminations,\nreconstruction of atoms on the surface is the central mechanism to avoid the so\ncalled polar catastrophe. This adds to the complexity of the reconstruction\nwhere charge polarization and stoichiometry govern the final surface in\naddition to standard thermodynamic parameters such as temperature and partial\npressure. Here we present direct, in-situ determination of polar SrTiO3 (110)\nsurfaces at temperatures up to 900 C using cross-sectional aberration corrected\nscanning transmission electron microscopy (STEM). Under these conditions, we\nobserve the coexistence of various surface structures that change as a function\nof temperature. As the specimen temperature is lowered, the reconstructed\nsurface evolves due to thermal mismatch with the substrate. Periodic defects,\nsimilar to dislocations, are found in these surface structures and act to\nrelieve stress due to mismatch. Combining STEM observations and electron\nspectroscopy with density functional theory, we find a combination of lattice\nmisfit and charge compensation for stabilization. Beyond the characterization\nof these complex reconstructions, we have developed a general framework that\nopens a new pathway to simultaneously investigate the surface and near surface\nregions of single crystals as a function of environment."
    },
    {
        "anchor": "Characterization of high-quality MgB2(0001) epitaxial films on Mg(0001): High-grade MgB2(0001) films were grown on Mg(0001) by means of\nultra-high-vacuum molecular beam epitaxy. Low energy electron diffraction and\nx-ray diffraction data indicate that thick films are formed by epitaxially\noriented grains with MgB2 bulk structure. The quality of the films allowed\nangle-resolved photoemission and polarization dependent x-ray absorption\nmeasurements. For the first time, we report the band mapping along the Gamma-A\ndirection and the estimation of the electron-phonon coupling constant l ~ 0.55\nfor the surface state electrons.",
        "positive": "Autonomous Repair in Cementitous Material by Combination of\n  Superabsorbent Polymers and Polypropylene Fibres: A Step Towards Sustainable\n  Infrastructure: Manual maintenance and repair of cracks in concrete structures are often\nunsustainable because of associated labor, capital and environmental damage.\nIntroduction of microfibers and superabsorbent polymers is a material solution\nto restrict crack propagation and enhance self-healing efficiency. Therefore,\nthe study proposes a combination of polypropylene(PP) fibers and superabsorbent\npolymers (SAP) which would facilitate autonomous healing and recover original\nmechanical and durability properties of mortar. Mechanical strength, sorptivity\nand water penetration of healed mortars were compared to that of undamaged\nmortar at same age to estimate recovery of original properties while crack\nsealing was investigated by means of optical microscopy. Experimental results\nshow mortar with combination of PP fibers and SAP showed full recovery of\nmechanical strength after healing while recovery in durability up to 90% was\nrecorded. Microscopic images show that average crack-sealing ratio of 85% could\nbe achieved under moist condition by combination of SAP and PP fibers while\nsealing under drier air curing condition is also significantly higher than\nreference samples with only fibers. Crack width up to 330{\\mu}m has been found\nto be completely sealed by carbonate crystals. Furthermore, mortar with SAP and\nPP fibers retain about 70% of their original 28-day strength after three cycles\nof loading while reference mortar samples were found to retain only about\n40-50% of their original strength. Effective crack sealing and high recovery of\noriginal properties in mortars with SAP and fibers suggest that this material\ncombination would reduce the need for environmentally damaging and expensive\nrepairs during the service life."
    },
    {
        "anchor": "X-ray scattering from stepped and kinked surfaces: An approach with the\n  paracrystal model: A general formalism of X-ray scattering from different kinds of surface\nmorphologies is described. Based on a description of the surface morphology at\nthe atomic scale through the use of the paracrystal model and discrete\ndistributions of distances, the scattered intensity by non-periodic surfaces is\ncalculated over the whole reciprocal space. In one dimension, the scattered\nintensity by a vicinal surface, the two-level model, the N-level model, the\nfaceted surface and the rough surface are addressed. In two dimensions, the\nprevious results are generalized to the kinked vicinal surface, the two-level\nvicinal surface and the step meandering on a vicinal surface. The concept of\ncrystal truncation rod is generalized considering also the truncation of a\nterrace by a step (yielding a terrace truncation rod) and a step by a kink\n(yielding a step truncation rod).",
        "positive": "$Ab~initio$ studies of Co$_2$FeAl$_{1-x}$Si$_x$ Heusler alloys: We present results of extensive theoretical studies of\nCo$_2$FeAl$_{1-x}$Si$_x$ Heusler alloys, which have been performed in the\nframework of density functional theory employing the all-electron\nfull-potential linearized augmented plane-wave scheme. It is shown that the\nSi-rich alloys are more resistive to structural disorder and as a consequence\nSi stabilizes the $L2_1$ structure. Si alloying changes position of the Fermi\nlevel, pushing it into the gap of the minority spin-band. It is also shown that\nthe hyperfine field on Co nuclei increases with the Si concentration, and this\nincrease originates mostly from the changes in the electronic density of the\nvalence electrons."
    },
    {
        "anchor": "Strain-Tunable Magnetocrystalline Anisotropy in Epitaxial Y3Fe5O12 Thin\n  Films: We demonstrate strain-tuning of magnetocrystalline anisotropy over a range of\nmore than one thousand Gauss in epitaxial Y3Fe5O12 films of excellent\ncrystalline quality grown on lattice-mismatched Y3Al5O12 substrates.\nFerromagnetic resonance (FMR) measurements reveal a linear dependence of both\nout-of-plane and in-plane uniaxial anisotropy on the strain-induced tetragonal\ndistortion of Y3Fe5O12. Importantly, we find the spin mixing conductance G_r\ndetermined from inverse spin Hall effect and FMR linewidth broadening remains\nlarge: G_r = 3.33 x 10^14 Ohm^-1m^-2 in Pt/Y3Fe5O12/Y3Al5O12 heterostructures,\nquite comparable to the value found in Pt/Y3Fe5O12 grown on lattice-matched\nGd3Ga5O12 substrates.",
        "positive": "Periodic Variation of Stress in Sputter Deposited Si/WSi2 Multilayers: A tension increment after sputter deposition of 1 nm of WSi2 onto sputtered\nSi was observed at low Ar gas pressures. Wafer curvature data on multilayers\nwere found to have a periodic variation corresponding to the multilayer period,\nand this permitted statistical analyses to improve the sensitivity to small\nstresses. The observation of tension instead of compression in the initial\nstage of growth is new and a model invoking surface rearrangement is invoked.\nThe data also bear on an unusual surface smoothing phenomena for sputtered Si\nsurfaces caused by the sputter deposition of WSi2 . We furthermore report that\nfor low Ar pressures the Si layers are the predominant source of built-up\nstress."
    },
    {
        "anchor": "Atomic-resolution TEM Studies of Pillar-Matrix Structures in Epitaxially\n  Grown Ultrathin ZrO2-La2/3Sr1/3MnO3 Films: We studied ZrO2-La2/3Sr1/3MnO3 pillar matrix thin films which were found to\nshow anomalous magnetic and electron transport properties controlled by the\namount of ZrO2. With the application of an aberration corrected transmission\nelectron microscope, structure and chemical information of the system,\nespecially of the pillar matrix interface were revealed at atomic resolution.\nMinor amounts of Zr were found to occupy Mn positions within the matrix and its\nsolubility within the matrix was found to be less than 6 mol%. Moreover, the Zr\nconcentration reached minimum concentration at the pillar matrix interface\naccompanied by oxygen deficiency. La and Mn diffusion into the pillar was\nobserved along with a change of the Mn valence state. La and Mn positions\ninside ZrO2 pillars were also revealed at atomic resolution. These results\nprovide detailed information for future studies of macroscopic properties of\nthese materials.",
        "positive": "First-principles calculations that clarify energetics and reactions of\n  oxygen adsorption and carbon desorption on 4H-SiC ($11\\bar20$) surface: We report static and dynamic first-principles calculations that provide\natomistic pictures of the initial stage of the oxidation processes occurring at\nthe ($11\\bar20$) surface of 4H-SiC. Our results unveil reaction pathways and\ntheir associated free-energy barriers for the adsorption of oxygen and the\ndesorption of carbon atoms. We find that oxygen adsorption shows structural\nmulti-stability and that the surface-bridge sites are the most stable and\ncrucial sites for subsequent oxidation. We find that an approaching O$_2$\nmolecule is adsorbed, then dissociated and finally migrates toward these\nsurface-bridge sites with a free-energy barrier of 0.7 eV at the ($11\\bar20$)\nsurface. We also find that a CO molecule is desorbed from the metastable\noxidized structure upon the overcoming of a free-energy barrier of 2.4$\\sim$2.6\neV, thus constituting one of the annihilation process of C during the\noxidation. The results of the CO molecule desorption on the ($11\\bar20$)\nsurface are compared with the ($000\\bar1$) surface. A catalytic effect of\ndangling bonds at the surface, causing a drastic reduction of the CO desorption\nenergy, is found on the ($000\\bar1$) surface and the microscopic picture of the\neffect is ascribed to an electron transfer from the Si to C dangling bonds. The\nintrinsic ($11\\bar20$) surface does not show this catalytic effect, and this is\nbecause the surface consists of an equal amount of Si and C dangling bonds and\nthe electron transfer occurs before the desorption."
    },
    {
        "anchor": "The Rendering from the Periodic System of the Elements on the stability,\n  elastic, and electronic properties of M2AC phases: MAX phases are nanolaminated ternary materials that combine metallic and\nceramic properties. Currently, the A-site elements replacement in traditional\nones by later transition-metals opens a door to explore new types of MAX\nphases. In this work, we performed a systematic first-principle study to\nexplore trends in stability, electronic structure and mechanical properties of\n288 compositions of M2AX phases (M=Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W; A=Al, Si,\nP, S, Ga, Ge, As, Se, In, Sn, Sb, Te, Tl, Pb, Bi, Mn, Fe, Co, Ni, Cu, Zn, Tc,\nRu, Rh, Pd, Ag, Cd, Os, Ir, Pt, Au, Hg; X=C). Such a dataset, combined with the\nrigid-band model been applied to most transition metal carbides, shows us the\nfundamental trends in bonding mechanisms and mechanical properties of MAX\nphases endowed with the periodic arrangements of M/A-site elements. It worth\nnoting, in particular, the M-A d-d interactions of MAX phases uniquely\ncontribute to the elastic constant C33.",
        "positive": "Voltage-dependent spin flip in magnetically-substituted graphene\n  nanoribbons: Toward the realization of graphene-based spintronic devices: We examine the possibility of using graphene nanoribbons (GNRs) with directly\nsubstituted chromium atoms as spintronic device. Using density functional\ntheory, we simulate a voltage bias across a constructed GNR in a device setup,\nwhere a magnetic dimer has been substituted into the lattice. Through this\nfirst principles approach, we calculate the electronic and magnetic properties\nas a function of Hubbard U, voltage, and magnetic configuration. By calculating\nof the total energy of each magnetic configuration, we determine that initial\nantiferromagnetic ground state flips to a ferromagnetic state with applied\nbias. Mapping this transition point to the calculated conductance for the\nsystem reveals that there is a distinct change in conductance through the GNR,\nwhich indicates the possibility of a spin valve. We also show that this\ncorresponds to a distinct change in the induced magnetization within the\ngraphene."
    },
    {
        "anchor": "Minimum energy path for the nucleation of misfit dislocations in\n  Ge/Si(001) heteroepitaxy: A possible mechanism for the formation of a 90{\\deg} misfit dislocation at\nthe Ge/Si(001) interface through homogeneous nucleation is identified from\natomic scale calculations where a minimum energy path connecting the coherent\nepitaxial state and a final state with a 90{\\deg} misfit dislocation is found\nusing the nudged elastic band method. The initial path is generated using a\nrepulsive bias activation procedure in a model system including 75000 atoms.\nThe energy along the path exhibits two maxima in the energy. The first maximum\noccurs as a 60{\\deg} dislocation nucleates. The intermediate minimum\ncorresponds to an extended 60{\\deg} dislocation. The subsequent energy maximum\noccurs as a second 60{\\deg} dislocation nucleates in a complementary, mirror\nglide plane, simultaneously starting from the surface and from the first\n60{\\deg} dislocation. The activation energy of the nucleation of the second\ndislocation is 30% lower than that of the first one showing that the formation\nof the second 60{\\deg} dislocation is aided by the presence of the first one.\nThe simulations represent a step towards unraveling the formation mechanism of\n90{\\deg} dislocations, an important issue in the design of growth procedures\nfor strain released Ge overlayers on Si(100) surfaces, and more generally\nillustrate an approach that can be used to gain insight into the mechanism of\ncomplex nucleation paths of extended defects in solids.",
        "positive": "Dynamical stability of two-dimensional metals in the periodic table: We study the dynamical stability of elemental two-dimensional (2D) metals\nfrom Li to Pb by calculating the phonon band structure from first principles,\nwhere 2D structures are assumed to be planer hexagonal, buckled honeycomb, and\nbuckled square lattice structures. We show the relationship between the\nstability of 2D structures and that of three-dimensional structures. This\nprovides a material design concept for alloys, where the similarity with regard\nto the stable 2D structures, rather than the energetic stability of alloy, is\nimportant to yield dynamically stable alloys."
    },
    {
        "anchor": "Classification of second harmonic generation effect in magnetically\n  ordered materials: The relationship between magnetic order and the second harmonic generation\n(SHG) effect is a fundamental area of study in condensed matter physics with\nsignificant practical implications. In order to gain a clearer understanding of\nthis intricate relation, this study presents a comprehensive classification\nscheme for the SHG effect in magnetically ordered materials. This framework\noffers a straightforward approach to connect magnetic order and SHG effect. The\ncharacteristics of the SHG tensors in all magnetic point groups are studied\nusing the isomorphic group method, followed by a comprehensive SHG effect\nclassification scheme that includes seven types based on the symmetries of the\nmagnetic phases and their corresponding parent phases. In addition, a tensor\ndictionary containing the SHG and linear magneto-optic (LMO) effect is\nestablished. Furthermore, an extensive SHG database of magnetically ordered\nmaterials is also built up. This classification strategy exposes an anomalous\nSHG effect with even characteristic under time-reversal symmetry, which is\nsolely contributed by magnetic structure. Moreover, the proposed classification\nscheme facilitates the determination of magnetic structures through SHG effect.",
        "positive": "Strain Fields and the Electronic Structure of Antiferromagnetic CrN: We present a theoretical analysis of the role that strain plays on the\nelectronic structure of chromium nitride crystals. We use LSDA+U calculations\nto study the elastic constants, deforma- tion potentials and strain dependence\nof electron and hole masses near the fundamental gap. We consider the lowest\nenergy antiferromagnetic models believed to describe CrN at low temperatures,\nand apply strain along different directions. We find relatively large\ndeformation potentials for all models, and find increasing gaps for tensile\nstrain along most directions. Most interestingly, we find that compressive\nstrains should be able to close the relatively small indirect gap (' 100 meV)\nat moderate amplitudes ' 1.3%. We also find large and anisotropic changes in\nthe effective masses with strain, with principal axes closely related to the\nmagnetic ordering of neighboring layers in the antiferromagnet. It would be\ninteresting to consider the role that these effects may have on typical film\ngrowth on different substrates, and the possibility of monitoring optical and\ntransport properties of thin films as strain is applied."
    },
    {
        "anchor": "Towards First-principles Electrochemistry: Chemisorbed molecules at a fuel cell electrode are a very sensitive probe of\nthe surrounding electrochemical environment, and one that can be accurately\nmonitored with different spectroscopic techniques. We develop a comprehensive\nelectrochemical model to study molecular chemisorption at either constant\ncharge or fixed applied voltage, and calculate from first principles the\nvoltage dependence of vibrational frequencies -- the vibrational Stark effect\n-- for CO adsorbed on close-packed platinum electrodes. The predicted\nvibrational Stark slopes are found to be in very good agreement with\nexperimental electrochemical spectroscopy data, thereby resolving previous\ncontroversies in the quantitative interpretation of in-situ experiments and\nelucidating the relation between canonical and grand-canonicaldescriptions of\nvibrational surface phenomena.",
        "positive": "Dispersion Interaction of Atoms with Single-Walled Carbon Nanotubes\n  described by the Dirac Model: We calculate the interaction energy and force between atoms and molecules and\nsingle-walled carbon nanotubes described by the Dirac model of graphene. For\nthis purpose the Lifshitz-type formulas adapted for the case of cylindrical\ngeometry with the help of the proximity force approximation are used. The\nresults obtained are compared with those derived from the hydrodymanic model of\ngraphene. Numerical computations are performed for hydrogen atoms and\nmolecules. It is shown that the Dirac model leads to larger values of the van\nder Waals force than the hydrodynamic model. For a hydrogen molecule the\ninteraction energy and force computed using both models are larger than for a\nhydrogen atom."
    },
    {
        "anchor": "Conductance Model for Single-Crystalline/Compact Metal Oxide Gas Sensing\n  Layers in the Non-Degenerate Limit: Example of Epitaxial SnO$_2$(101): Semiconducting metal oxide (SMOX)-based gas sensors are indispensable for\nsafety and health applications, e.g. explosive, toxic gas alarms, controls for\nintake into car cabins and monitor for industrial processes. In the past, the\nsensor community has been studying polycrystalline materials as sensors where\nthe porous and random microstructure of the SMOX does not allow a separation of\nthe phenomena involved in the sensing process. This lead to conduction models\nthat can model and predict the behavior of the overall response, but they were\nnot capable of giving fundamental information regarding the basic mechanisms\ntaking place. The study of epitaxial layers is the definite prove to clarify\nthe different aspects and contributions of the sensing mechanisms that are not\npossible to do by studying a polycrystalline sample. A detailed analytical\nmodel for n and p-type single-crystalline/compact metal oxide gas sensors was\ndeveloped that directly relates the conductance of the sample with changes in\nthe surface electrostatic potential. Combined DC resistance and work function\nmeasurements were used in a compact SnO2 (101) layer in operando conditions\nthat allowed us to check the validity of our model in the region where\nBoltzmann approximation holds to determine surface and bulk properties of the\nmaterial.",
        "positive": "Shearing Mechanisms of Co-Precipitates in IN718: The Ni-base superalloy 718 is the most widely used material for\nturbomachinery in the aerospace industry and land-based turbines. Although the\nrelationship between processing and the resulting properties is well known, an\nunderstanding of the specific deformation mechanisms activated across its\napplication temperature range is required to create more mechanistically\naccurate property models. Direct atomic-scale imaging observations with high\nangle annular dark-field scanning transmission electron microscopy,\ncomplemented by phase-field modeling informed by generalized stacking fault\nsurface calculations using density functional theory, were employed to\nunderstand the shear process of ${\\gamma}''$ and ${\\gamma}'/{\\gamma}''$\nco-precipitates after 1 \\% macroscopic strain at lower temperature (ambient and\n$427 {\\deg}C$). Experimentally, intrinsic stacking faults were observed in the\n${\\gamma}''$, whereas the ${\\gamma}'$ was found to exhibit anti-phase\nboundaries or superlattice intrinsic stacking faults. Additionally, the\natomically flat ${\\gamma}'/{\\gamma}''$ interfaces in the co-precipitates were\nfound to exhibit offsets after shearing, which can be used as tracers for the\ndeformation events. Phase-field modeling shows that the developing\nfault-structure is dependent on the direction of the Burgers vector of the $a/2\n\\langle110\\rangle$ matrix dislocation (or dislocation group) due to the lower\ncrystal symmetry of the ${\\gamma''}$ phase. The interplay between ${\\gamma}'$\nand ${\\gamma}''$ phases results in unique deformation pathways of the\nco-precipitate and increases the shear resistance. Consistent with the\nexperimental observations, the simulation results indicate that complex\nshearing mechanisms are active in the low-temperature deformation regime and\nthat multiple $a/2 \\langle110\\rangle$ dislocations of non-parallel Burgers\nvectors may be active on the same slip plane."
    },
    {
        "anchor": "Observations of an Edge-enhancing Instability in Snow Crystal Growth\n  near -15 C: We present observations of the formation of plate-like snow crystals that\nprovide evidence for an edge-enhancing crystal growth instability. This\ninstability arises when the condensation coefficient describing the growth of\nan ice prism facet increases as the width of the facet becomes narrower.\nCoupled with the effects of particle diffusion, this phenomenon causes thin\nplate-like crystals to develop from thicker prisms, sharpening the edges of the\nplates to micron or sub-micron dimensions as they grow. This sharpening effect\nis largely responsible for the formation of thin plate-like ice crystals from\nwater vapor near -15 C, which is a dominant feature in the snow crystal\nmorphology diagram. Other faceted crystalline materials may exhibit similar\nmorphological growth instabilities that promote the diffusion-limited growth of\nplate-like or needle-like structures.",
        "positive": "Negative differential resistance in molecular junctions: The effect of\n  the electrodes electronic structure: We have carried out calculations of electron transport through a\nmetal-molecule-metal junction with metal nanoclusters taking the part of\nelectrodes. We show that negative differential resistance peaks could appear in\nthe current-voltage curves. The peaks arise due to narrow features in the\nelectron density of states of the metal clusters. The proposed analysis is\nbased on the ab initio computations of the relevant wave functions and energies\nwithin the framework of the density functional theory using NRLMOL software\npackage."
    },
    {
        "anchor": "Using photoelectron spectroscopy to measure resonant inelastic X-ray\n  scattering: A computational investigation: Resonant inelastic X-ray scattering (RIXS) has become an important scientific\ntool. Nonetheless, conventional high-resolution RIXS measurements (<100 meV),\nespecially in the soft x-ray range, require large and low-throughput grating\nspectrometers that limits measurement accuracy and simplicity. Here, we\ncomputationally investigate the performance of a different method for measuring\nRIXS, Photoelectron Spectrometry for Analysis of X-rays (PAX). This method\ntransforms the X-ray measurement problem of RIXS to an electron measurement\nproblem, enabling use of compact, high-throughput electron spectrometers. In\nPAX, X-rays to be measured are incident on a converter material and the energy\ndistribution of the resultant photoelectrons, the PAX spectrum, is measured\nwith an electron spectrometer. The incident X-ray spectrum is then estimated\nthrough a deconvolution algorithm that leverages concepts from machine\nlearning. We investigate a few example PAX cases. Using the 3d levels of Ag as\na converter material, and with 10$^5$ detected electrons, we accurately\nestimate features with 100s of meV width in a model RIXS spectrum. Using a\nsharp Fermi edge to encode RIXS spectra, we accurately distinguish 100 meV FWHM\npeaks separated by 45 meV with 10$^7$ electrons detected that were photoemitted\nfrom within 0.4 eV of the Fermi level.",
        "positive": "Temporal evolution of mesoscopic structure of some non-Euclidean systems\n  using a Monte Carlo model: A Monte Carlo based computer model is presented to comprehend the contrasting\nobservations of Mazumder et al. [Phys. Rev. Lett. 93, 255704 (2004) and Phys.\nRev. B 72, 224208 (2005)], based on neutron-scattering measurements, on\ntemporal evolution of effective fractal dimension and characteristic length for\nhydration of cement with light and heavy water. In this context, a theoretical\nmodel is also proposed to elucidate the same."
    },
    {
        "anchor": "AFLOW-SYM: Platform for the complete, automatic and self-consistent\n  symmetry analysis of crystals: Determination of the symmetry profile of structures is a persistent challenge\nin materials science. Results often vary amongst standard packages, hindering\nautonomous materials development by requiring continuous user attention and\neducated guesses. Here, we present a robust procedure for evaluating the\ncomplete suite of symmetry properties, featuring various representations for\nthe point-, factor-, space groups, site symmetries, and Wyckoff positions. The\nprotocol determines a system-specific mapping tolerance that yields symmetry\noperations entirely commensurate with fundamental crystallographic principles.\nThe self consistent tolerance characterizes the effective spatial resolution of\nthe reported atomic positions. The approach is compared with the most used\nprograms and is successfully validated against the space group information\nprovided for over 54,000 entries in the Inorganic Crystal Structure Database.\nSubsequently, a complete symmetry analysis is applied to all 1.7$+$ million\nentries of the AFLOW data repository. The AFLOW-SYM package has been\nimplemented in, and made available for, public use through the automated,\n$\\textit{ab-initio}$ framework AFLOW.",
        "positive": "Investigation of the unidirectional spin heat conveyer effect in a 200nm\n  thin Yttrium Iron Garnet film: We have investigated the unidirectional spin wave heat conveyer effect in\nsub-micron thick yttrium iron garnet (YIG) films using lock-in thermography\n(LIT). Although the effect is small in thin layers this technique allows us to\nobserve asymmetric heat transport by magnons which leads to asymmetric\ntemperature profiles differing by several mK on both sides of the exciting\nantenna, respectively. Comparison of Damon-Eshbach and backward volume modes\nshows that the unidirectional heat flow is indeed due to non-reciprocal\nspin-waves. Because of the finite linewidth, small asymmetries can still be\nobserved when only the uniform mode of ferromagnetic resonance is excited. The\nlatter is of extreme importance for example when measuring the inverse\nspin-Hall effect because the temperature differences can result in\nthermovoltages at the contacts. Because of the non-reciprocity these\nthermovoltages reverse their sign with a reversal of the magnetic field which\nis typically deemed the signature of the inverse spin-Hall voltage."
    },
    {
        "anchor": "Perspectives in spintronics: magnetic resonant tunneling, spin-orbit\n  coupling, and GaMnAs: Spintronics has attracted wide attention by promising novel functionalities\nderived from both the electron charge and spin. While branching into new areas\nand creating new themes over the past years, the principal goals remain the\nspin and magnetic control of the electrical properties, essentially the I-V\ncharacteristics, and vice versa. There are great challenges ahead to meet these\ngoals. One challenge is to find niche applications for ferromagnetic\nsemiconductors, such as GaMnAs. Another is to develop further the science of\nhybrid ferromagnetic metal/semiconductor heterostructures, as alternatives to\nall-semiconductor room temperature spintronics. Here we present our\nrepresentative recent efiorts to address such challenges. We show how to make a\ndigital magnetoresistor by combining two magnetic resonant diodes, or how\nintroducing ferromagnetic semiconductors as active regions in resonant\ntunneling diodes leads to novel efiects of digital magnetoresistance and of\nmagnetoelectric current oscillations. We also discuss the phenomenon of\ntunneling anisotropic magnetoresistance in Fe/GaAs junctions by introducing the\nconcept of the spin-orbit coupling field, as an analog of such fields in\nall-semiconductor junctions. Finally, we look at fundamental electronic and\noptical properties of GaMnAs by employing reasonable tight-binding models to\nstudy disorder efiects.",
        "positive": "Electrical Detection of Spin Transport in Lateral\n  Ferromagnet-Semiconductor Devices: A longstanding goal of research in semiconductor spintronics is the ability\nto inject, modulate, and detect electron spin in a single device. A simple\nprototype consists of a lateral semiconductor channel with two ferromagnetic\ncontacts, one of which serves as a source of spin-polarized electrons and the\nother as a detector. Based on work in analogous metallic systems, two important\ncriteria have emerged for demonstrating electrical detection of spin transport.\nThe first is the measurement of a non-equilibrium spin population using a\nnon-local ferromagnetic detector through which no charge current flows. The\npotential at the detection electrode should be sensitive to the relative\nmagnetizations of the detector and the source electrodes, a property referred\nto as the spin-valve effect. A second and more rigorous test is the existence\nof a Hanle effect, which is the modulation and suppression of the spin valve\nsignal due to precession and dephasing in a transverse magnetic field. Here we\nreport on the observation of both the spin valve and Hanle effects in lateral\ndevices consisting of epitaxial Fe Schottky tunnel barrier contacts on an\nn-doped GaAs channel. The dependence on transverse magnetic field, temperature,\nand contact separation are in good agreement with a model incorporating spin\ndrift and diffusion. Spin transport is detected for both directions of current\nflow through the source electrode. The sign of the electrical detection signal\nis found to vary with the injection current and is correlated with the spin\npolarization in the GaAs channel determined by optical measurements. These\nresults therefore demonstrate a fully electrical scheme for spin injection,\ntransport, and detection in a lateral semiconductor device."
    },
    {
        "anchor": "Ab Initio Velocity-Field Curves in Monoclinic\n  \\(\u03b2\\)-Ga\\textsubscript{2}O\\textsubscript{3}}: We investigate the high-field transport in monoclinic\n\\(\\beta\\)-Ga\\textsubscript{2}O\\textsubscript{3}} using a combination of ab\ninitio calculations and full band Monte Carlo (FBMC) simulation. Scattering\nrate calculation and the final state selection in the FBMC simulation use\ncomplete wave-vector (both electron and phonon) and crystal direction dependent\nelectron phonon interaction (EPI) elements. We propose and implement a\nsemi-coarse version of the Wannier-Fourier interpolation method [F. Giustino,\nM. L. Cohen, and S. G. Louie, Physical Review B, vol. 76, no. 16, 2007] for\nshort-range non-polar optical phonon (EPI) elements in order to ease the\ncomputational requirement in FBMC simulation. During the interpolation of the\nEPI, the inverse Fourier sum over the real-space electronic grids is done on a\ncoarse mesh while the unitary rotations are done on a fine mesh. This paper\nreports the high field transport in monoclinic\n\\(\\beta\\)-Ga\\textsubscript{2}O\\textsubscript{3}} with deep insight on the\ncontribution of electron-phonon interactions, and velocity-field\ncharacteristics for electric fields ranging up to 450 kV/cm in different\ncrystal directions. A peak velocity of $2\\times10^{7}& cm/s is estimated at an\nelectric field of 200 kV/cm.",
        "positive": "Bipolar Conduction is the Origin of the Electronic Transition in\n  Pentatellurides: Metallic vs. Semiconducting Behavior: The pentatellurides, ZrTe5 and HfTe5 are layered compounds with one\ndimensional transition-metal chains that show a never understood temperature\ndependent transition in transport properties as well as recently discovered\nproperties suggesting topological semimetallic behavior. Here we show that\nthese materials are semiconductors and that the electronic transition is due to\na combination of bipolar effects and different anisotropies for electrons and\nholes. We report magneto-transport properties for two kinds of ZrTe5 single\ncrystals grown with the chemical vapor transport (S1) and the flux method (S2),\nrespectively. These have distinct transport properties at zero field: the S1\ndisplays a metallic behavior with a pronounced resistance peak and a sudden\nsign reversal in thermopower at approximately 130 K, consistent with previous\nobservations of the electronic transition; in strikingly contrast, the S2\nexhibits a semiconducting-like behavior at low temperatures and a positive\nthermopower over the whole temperature range. Refinements on the single-crystal\nX-ray diffraction and the energy dispersive spectroscopy analysis revealed the\npresence of noticeable Te-vacancies in the sample S1, confirming that the\nwidely observed anomalous transport behaviors in pentatellurides actually take\nplace in the Te-deficient samples. Electronic structure calculations show\nnarrow gap semiconducting behavior, with different transport anisotropies for\nholes and electrons. For the degenerately doped n-type samples, our transport\ncalculations can result in a resistivity peak and crossover in thermopower from\nnegative to positive at temperatures close to that observed experimentally. Our\npresent work resolves the longstanding puzzle regarding the anomalous transport\nbehaviors of pentatellurides, and also resolves the electronic structure in\nfavor of a semiconducting state."
    },
    {
        "anchor": "Disentangling magnetic hardening and molecular spin chain contributions\n  to exchange bias in ferromagnet/molecule bilayers: We performed SQUID and FMR magnetometry experiments to clarify the\nrelationship between two reported magnetic exchange effects arising from\ninterfacial spin-polarized charge transfer within ferromagnetic metal\n(FM)/molecule bilayers: the magnetic hardening effect, and\nspinterface-stabilized molecular spin chains. To disentangle these effects,\nboth of which can affect the FM magnetization reversal, we tuned the metal\nphthalocyanine molecule central site's magnetic moment to selectively enhance\nor suppress the formation of spin chains within the molecular film. We find\nthat both effects are distinct, and additive. In the process, we 1) extended\nthe list of FM/molecule candidate pairs that are known to generate magnetic\nexchange effects, 2) experimentally confirmed the predicted increase in\nanisotropy upon molecular adsorption; and 3) showed that spin chains within the\nmolecular film can enhance magnetic exchange. This magnetic ordering within the\norganic layer implies a structural ordering. Thus, by distengangling the\nmagnetic hardening and exchange bias contributions, our results confirm, as an\necho to progress regarding inorganic spintronic tunnelling, that the milestone\nof spintronic tunnelling across structurally ordered organic barriers has been\nreached through previous magnetotransport experiments. This paves the way for\nsolid-state devices studies that exploit the quantum physical properties of\nspin chains, notably through external stimuli.",
        "positive": "Prediction of a wide variety of linear complexions in face centered\n  cubic alloys: Linear complexions are defect states that have been recently discovered along\ndislocations in body centered cubic Fe-based alloys. In this work, we use\natomistic simulations to extend this concept and explore segregation-driven\nstructural transitions at dislocations in face centered cubic alloys. We\nidentify a variety of stable, nanoscale-size structural and chemical states,\nwhich are confined near dislocations and can be classified as linear\ncomplexions. Depending on the alloy system and thermodynamic conditions, such\nnew states can preserve, partially modify, or completely replace the original\ndefects they were born at. By considering different temperatures and\ncompositions, we construct linear complexion diagrams that are similar to bulk\nphase diagrams, defining the important conditions for complexion formation\nwhile also specifying an expected complexion size and type. Several notable new\ncomplexion types were predicted here: (1) nanoparticle arrays comprised of L12\nphases in Ni-Fe, Ni-Al, and Al-Zr, (2) replacement of stacking faults with\nlayered complexions comprised of (111) planes from the Cu5Zr intermetallic\nphase in Cu-Zr, (3) platelet arrays comprised of two-dimensional\nGuinier-Preston zones in Al-Cu, and finally (4) coexistence of multiple linear\ncomplexions containing both Guinier-Preston zones and L12 phases in ternary\nAl-Cu-Zr. All of these new complexion states are expected to alter material\nproperties and affect the stability of the dislocations themselves, offering a\nunique opportunity for future materials design."
    },
    {
        "anchor": "Identical response of insulators to irradiations by swift heavy ions:\n  application to experiments on Gd2Ti2O7: Track radii Re induced by swift heavy ions are studied. The experimental\ntrack data are analyzed in Gd2Ti2O7 pyrochlore in the range Se=6-54 keV/nm (Se\n- electronic stopping power) including irradiations by low and high velocity\nions. The Analytical Thermal Spike Model (ATSM) is applied whose main features\nare reviewed. The track data of Gd2Ti2O7 exhibit scaling features which mean\nsimple quantitative relationships with track sizes of other insulators\ncontrolled only by a single materials parameter (MP), the melting temperature\nTm. The Re2-Se track evolution curve is described in the whole range of Se\nwithout the application of any individual fitting parameter and MPs apart Tm;\nthe threshold for track formation Set=6.1/14.4 keV/nm for E<2 MeV/nucleon and\nE>8 MeV/nucleon, respectively. The unique role of Tm is a highly important\nlimitation for the mechanism of track formation. The practical consequences of\nthe results are discussed with respect of the estimation of irradiation\nparameters",
        "positive": "A Planning-and-Exploring Approach to Extreme-Mechanics Force Fields: Extreme mechanical processes such as strong lattice distortion and bond\nbreakage during fracture are ubiquitous in nature and engineering, which often\nlead to catastrophic failure of structures. However, understanding the\nnucleation and growth of cracks is challenged by their multiscale\ncharacteristics spanning from atomic-level structures at the crack tip to the\nstructural features where the load is applied. Molecular simulations offer an\nimportant tool to resolve the progressive microstructural changes at crack\nfronts and are widely used to explore processes therein, such as mechanical\nenergy dissipation, crack path selection, and dynamic instabilities (e.g.,\nkinking, branching). Empirical force fields developed based on local\ndescriptors based on atomic positions and the bond orders do not yield\nsatisfying predictions of fracture, even for the nonlinear, anisotropic\nstress-strain relations and the energy densities of edges. High-fidelity force\nfields thus should include the tensorial nature of strain and the energetics of\nrare events during fracture, which, unfortunately, have not been taken into\naccount in both the state-of-the-art empirical and machine-learning force\nfields. Based on data generated by first-principles calculations, we develop a\nneural network-based force field for fracture, NN-F$^3$, by combining\npre-sampling of the space of strain states and active-learning techniques to\nexplore the transition states at critical bonding distances. The capability of\nNN-F$^3$ is demonstrated by studying the rupture of h-BN and twisted bilayer\ngraphene as model problems. The simulation results confirm recent experimental\nfindings and highlight the necessity to include the knowledge of electronic\nstructures from first-principles calculations in predicting extreme mechanical\nprocesses."
    },
    {
        "anchor": "Enhancement of chemical activity in corrugated graphene: Simulation of chemical activity of corrugated graphene within density\nfunctional theory predicts an enhancement of its chemical activity if the ratio\nof height of the corrugation (ripple) to its radius is larger than 0.07.\nFurther growth of the curvature of the ripples results in appearance of midgap\nstates which leads to an additional strong increase of chemisororption energy.\nThese results open a way for tunable functionalization of graphene, namely,\ndepending of curvature of the ripples one can provide both homogeneous (for\nsmall curvatures) and spot-like (for large curvatures) functionalization.",
        "positive": "Picosecond all-optical switching of magnetic tunnel junctions: Control of magnetism without using magnetic fields enables large-scale\nintegration of spintronic devices for memory, computation and communication in\nthe beyond-CMOS era. Mechanisms including spin torque transfer, spin Hall\neffect, and electric field or strain assisted switching have been implemented\nto switch magnetization in various spintronic devices. Their operation speed,\nhowever, is fundamentally limited by the spin precession time to be longer than\n10-100 picoseconds. Overcoming such a speed constraint is critical for the\nprospective development of spintronics. Here we report the demonstration of\npicosecond all-optical switching of a magnetic tunnel junction (MTJ)- the\nbuilding block of spintronic logic and memory -only using single telecom-band,\ninfrared laser pulses. This first optically switchable MTJ uses ferrimagnetic\nGdFeCo as the free layer, and its switching is directly readout by measuring\nits tunneling magnetoresistance with a DR/R ratio of 0.6%. An instrument\nlimited switching repetition rate at MHz has been demonstrated, but the\nfundamental limit should be higher than tens of GHz. This result represents an\nimportant step toward integrated opto-spintronic devices that combines\nspintronics and photonics technologies to enable ultrafast conversion between\nfundamental information carriers of electron spins and photons."
    },
    {
        "anchor": "Electroresistance effects in ferroelectric tunnel barriers: Electron transport through fully depleted ferroelectric tunnel barriers\nsandwiched between two metal electrodes and its dependence on ferroelectric\npolarization direction are investigated. The model assumes a polarization\ndirection dependent ferroelectric barrier. The transport mechanisms, including\ndirect tunneling, Fowler-Nordheim tunneling and thermionic injection, are\nconsidered in the calculation of the electroresistance as a function of\nferroelectric barrier properties, given by the properties of the ferroelectric,\nthe barrier thickness, and the metal properties, and in turn of the\npolarization direction. Large electroresistance is favored in thicker films for\nall three transport mechanisms but on the expense of current density. However,\nswitching between two transport mechanisms, i.e., direct tunneling and\nFowler-Nordheim tunneling, by polarization switching yields a large\nelectroresistance. Furthermore, the most versatile playground in optimizing the\ndevice performance was found to be the electrode properties, especially\nscreening length and band offset with the ferroelectric.",
        "positive": "Performances of a Newly High Sensitive Trilayer F/Cu/F GMI Sensor: We have selected stress-annealed nanocrystalline Fe-based ribbons for\nferromagnetic/copper/ferromagnetic sensors exhibiting high magneto-impedance\nratio. Longitudinal magneto-impedance reaches 400% at 60 kHz and longitudinal\nmagneto-resistance increases up to 1300% around 200 kHz."
    },
    {
        "anchor": "Non-equilibrium pathways to emergent polar supertextures: Ultrafast stimuli can stabilize metastable states of matter inaccessible by\nequilibrium means. Establishing the spatiotemporal link between ultrafast\nexcitation and metastability is crucial to understanding these phenomena. Here,\nwe use single-shot optical-pump, X-ray-probe measurements to provide snapshots\nof the emergence of a persistent polar vortex supercrystal in a heterostructure\nthat hosts a fine balance between built-in electrostatic and elastic\nfrustrations by design. By perturbing this balance with photoinduced charges, a\nstarting heterogenous mixture of polar phases disorders within a few\npicoseconds, resulting in a soup state composed of disordered ferroelectric and\nsuppressed vortex orders. On the pico-to-nanosecond timescales, transient\nlabyrinthine fluctuations form in this soup along with a recovering vortex\norder. On longer timescales, these fluctuations are progressively quenched by\ndynamical strain modulations, which drive the collective emergence of a single\nsupercrystal phase. Our results, corroborated by dynamical phase-field\nmodeling, reveal how ultrafast excitation of designer systems generates\npathways for persistent metastability.",
        "positive": "First principles interatomic potential for tungsten based on Gaussian\n  process regression: An accurate description of atomic interactions, such as that provided by\nfirst principles quantum mechanics, is fundamental to realistic prediction of\nthe properties that govern plasticity, fracture or crack propagation in metals.\nHowever, the computational complexity associated with modern schemes explicitly\nbased on quantum mechanics limits their applications to systems of a few\nhundreds of atoms at most.\n  This thesis investigates the application of the Gaussian Approximation\nPotential (GAP) scheme to atomistic modelling of tungsten - a bcc transition\nmetal which exhibits a brittle-to-ductile transition and whose plasticity\nbehaviour is controlled by the properties of $\\frac{1}{2} \\langle 111 \\rangle$\nscrew dislocations. We apply Gaussian process regression to interpolate the\nquantum-mechanical (QM) potential energy surface from a set of points in atomic\nconfiguration space. Our training data is based on QM information that is\ncomputed directly using density functional theory (DFT). To perform the\nfitting, we represent atomic environments using a set of rotationally,\npermutationally and reflection invariant parameters which act as the\nindependent variables in our equations of non-parametric, non-linear\nregression.\n  We develop a protocol for generating GAP models capable of describing lattice\ndefects in metals by building a series of interatomic potentials for tungsten.\nWe then demonstrate that a GAP potential based on a Smooth Overlap of Atomic\nPositions (SOAP) covariance function provides a description of the $\\frac{1}{2}\n\\langle 111 \\rangle$ screw dislocation that is in agreement with the DFT model.\nWe use this potential to simulate the mobility of $\\frac{1}{2} \\langle 111\n\\rangle$ screw dislocations by computing the Peierls barrier and model\ndislocation-vacancy interactions to QM accuracy in a system containing more\nthan 100,000 atoms."
    },
    {
        "anchor": "Machine Learning for compositional disorder: A Comparison Between\n  Different Descriptors and Machine Learning Frameworks: Compositional disorder is common in crystal compounds. In these compounds,\nsome atoms are randomly distributed at some crystallographic sites. For such\ncompounds, randomness forms many non-identical independent structures. Thus,\ncalculating the energy of all structures using ordinary quantum ab initio\nmethods can be significantly time-consuming. Machine learning can be a reliable\nalternative to ab initio methods. We calculate the energy of these compounds\nwith an accuracy close to that of density functional theory calculations in a\nconsiderably shorter time using machine learning. In this study, we use kernel\nridge regression and neural network to predict energy. In the KRR, we employ\nsine matrix, Ewald sum matrix, SOAP, ACSF, and MBTR. To implement the neural\nnetwork, we use two important classes of application of the neural network in\nmaterial science, including high-dimensional neural network and convolutional\nneural network based on crystal graph representation. We show that kernel ridge\nregression using MBTR and neural network using ACSF can provide better accuracy\nthan other methods.",
        "positive": "Electronic structures of organic molecule encapsulated BN nanotubes\n  under transverse electric field: The electronic structures of boron nitride nanotubes (BNNTs) doped by\ndifferent organic molecules under a transverse electric field were investigated\nvia first-principles calculations. The external field reduces the energy gap of\nBNNT, thus makes the molecular bands closer to the BNNT band edges and enhances\nthe charge transfers between BNNT and molecules. The effects of the electric\nfield direction on the band structure are negligible. The electric field\nshielding effect of BNNT to the inside organic molecules is discussed. Organic\nmolecule doping strongly modifies the optical property of BNNT, and the\nabsorption edge is red-shifted under static transverse electric field."
    },
    {
        "anchor": "Comparison of the Magnetic properties of Mn3Fe2Si3O12 as a crystalline\n  garnet and as a glass: The crystalline garnet Mn3Fe2Si3O12 and an amorphous phase of the same\nnominal composition are synthesized at high pressure. The magnetic properties\nof the two forms are reported. Both phases order antiferromagnetically. The\ncrystalline phase exhibits a Curie-Weiss theta of -47.2 K, with a sharp\nordering transition at 12 K. The glassy phase exhibits a larger\nantiferromagnetic Curie-Weiss theta, of -83.0 K, with a broad ordering\ntransition observed at 2.5 K. Both phases can be classified as magnetically\nfrustrated, although the amorphous phase shows a much higher degree of\nfrustration. The amorphous phase exhibits spin-glass behavior and is determined\nto have an actual composition of Mn3Fe2Si3O13.",
        "positive": "C60-Based Composites in View of Topochemical Reactions I. C60 Dimers and\n  Oligomers: The current paper opens a series of papers that are aimed at the\ndetermination of barriers that govern the covalent coupling between partners of\nC60-based composites consisting of two or more fullerenes C60 (C60 dimer and\noligomers) (Part 1), C60 and single-walled carbon nanotube ([C60+(4,4)] carbon\nnanobud) (Part 2), and C60 and graphene ([C60+(5,5)] and [C60+(9,8)] graphene\nnanobuds) (Part 3). C60 dimers and oligomers are considered in the current\npaper. The formation of composites is considered from the basic points related\nto the regioselective chemical reactivity of the fullerene molecule atoms. The\ndissonance between the predicted trimer and tetramer structures and\nexperimental observations is suggested to evidence the topological nature of\nthe C60 oligomerization. The barrier that governs the oligomer formation is\ndetermined in terms of the coupling energy and is expanded over two\ncontributions that present the total energy of deformation of the composites'\ncomponents and the energy of covalent coupling . The computations were\nperformed by using the AM1 semiempirical version of unrestricted broken\nsymmetry Hartree-Fock approach."
    },
    {
        "anchor": "Silicon cantilevers locally heated from 300K up to the melting point:\n  temperature profile measurement from their resonances frequency shift: When heated, micro-resonators present a shift of their resonance frequencies.\nWe study specifically silicon cantilevers heated locally by laser absorption,\nand evaluate theoretically and experimentally their temperature profile and its\ninterplay with the mechanical resonances. We present a enhanced version of our\nearlier model [F. Aguilar Sandoval et al., J. Appl. Phys. 117, 234503 (2015)]\nincluding both elasticity and geometry temperature dependency, showing that the\nlatter can account for 20% of the observed shift for the first flexural mode.\nThe temperature profile description takes into account thermal clamping\nconditions, radiation at high temperature, and lower conductivity than bulk\nsilicon due to phonon confinement. Thanks to a space-power equivalence in the\nheat equation, scanning the heating point along the cantilever directly reveals\nthe temperature profile. Finally, frequency shift measurement can be used to\ninfer the temperature field with a few percent precision.",
        "positive": "New high-pressure form of boron is significantly ionic: The comment of Dubrovinskaia et al. is scientifically flawed. The\nhigh-pressure form of boron, discovered by Oganov et al., is indeed new and its\nbonding has a significant ionic character, as demonstrated in Ref. 1."
    },
    {
        "anchor": "Extended Si defects: We perform total energy calculations based on the tight-binding Hamiltonian\nscheme (i) to study the structural properties and energetics of the extended\n{311} defects depending upon their dimensions and interstitial concentrations\nand (ii) to find possible mechanisms of interstitial capture by and release\nfrom the {311} defects. The generalized orbital-based linear-scaling method\nimplemented on Cray-T3D is used for supercell calculations of large scale\nsystems containing more than 1000 Si atoms.",
        "positive": "Effect of Fullerene on domain size and relaxation in a perpendicularly\n  magnetized Pt/Co/C60/Pt system: Buckminsterfullerene (C60) can exhibit ferromagnetism at the interface\n(called as a spinterface) when it is placed next to a ferromagnet (FM).\nFormation of such spinterface happens due to orbital hybridization and spin\npolarized charge transfer at the interface. The spinterface can influence the\ndomain size and dynamics of the organic/ferromagnetic heterostructure. Here, we\nhave performed magnetic domain imaging and studied the relaxation dynamics in\nPt/Co/C60/Pt system with perpendicular anisotropy. We have compared the results\nwith its parent Pt/Co/Pt system. It is observed that presence of C60 in the\nPt/Co/Pt system increases the anisotropy and a decrease in the bubble domain\nsize. Further the switching time of Pt/Co/C60/Pt system is almost two times\nfaster than Pt/Co/Pt system. We have also performed the spin polarized density\nfunctional theory (DFT) calculations to understand the underneath mechanism.\nDFT results show formation of a spin polarized spinterface which leads to an\nenhancement in anisotropy."
    },
    {
        "anchor": "Plastic yielding in nanocrystalline Pd-Au alloys mimics universal\n  behavior of metallic glasses: We studied solid solution effects on the mechanical properties of\nnanocrystalline (NC) $\\mathrm{Pd}_{\\mathrm{100-x}} \\mathrm{Au}_{\\mathrm{x}}$\nalloys ($0 \\leq \\mathrm{x} < 50 \\mathrm{at.\\%}$) at the low end of the\nnanoscale. Concentration has been used as control parameter to tune material\nproperties (elastic moduli, Burgers vector, stacking fault energies) at\nbasically unaltered microstructure (grain size $D\\approx 10\\mathrm{ nm}$). In\nstark contrast to coarse grained fcc alloys, we observe solid solution\nsoftening for increasing Au-content. The available predictions from models and\ntheories taking explicitly into account the effect of the nanoscale\nmicrostructure on the concentration-dependent shear strength have been\ndisproved without exception. As a consequence, it is implied that dislocation\nactivity contributes only marginally to strength. In fact, we find a linear\ncorrelation between shear strength and shear modulus which quantitatively\nagrees with the universal behavior of metallic glasses discovered by Johnson\nand Samwer [W.L. Johnson and K. Samwer, PRL 95, 195501 (2005)].",
        "positive": "High Performance n- and p-Type Field-Effect Transistors Based on\n  Hybridly Surface-Passivated Colloidal PbS Nanosheets: Colloidally synthesized nanomaterials are among the promising candidates for\nfuture electronic devices due to their simplicity and the inexpensiveness of\ntheir production. Specifically, colloidal nanosheets are of great interest\nsince they are conveniently producible through the colloidal approach while\nhaving the advantages of two-dimensionality. In order to employ these\nmaterials, according transistor behavior should be adjustable and of high\nperformance. We show that the transistor performance of colloidal lead sulfide\nnanosheets is tunable by altering the surface passivation, the contact metal,\nor by exposing them to air. We found that adding halide ions to the synthesis\nleads to an improvement of the conductivity, the field-effect mobility, and the\non/off ratio of these transistors by passivating their surface defects.\nSuperior n-type behavior with a field-effect mobility of 248 cm^2V^-1s^-1 and\nan on/off ratio of 4x10^6 is achieved. The conductivity of these stripes can be\nchanged from n-type to p-type by altering the contact metal and by adding\noxygen to the working environment. As a possible solution for the post-Moore\nera, realizing new high quality semiconductors such as colloidal materials is\ncrucial. In this respect, our results can provide new insights which helps to\naccelerate their optimization for potential applications."
    },
    {
        "anchor": "The Tin Pest Problem as a Test of Density Functionals Using\n  High-Throughput Calculations: At ambient pressure tin transforms from its ground-state semi-metal\n$\\alpha$-Sn (diamond structure) phase to the compact metallic $\\beta$-Sn phase\nat 13$^\\circ$C (286K). There may be a further transition to the simple\nhexagonal $\\gamma$-Sn above 450K. These relatively low transition temperatures\nare due to the small energy differences between the structures, $\\approx\n20$\\,meV/atom between $\\alpha$- and $\\beta$-Sn. This makes tin an exceptionally\nsensitive test of the accuracy of density functionals and computational\nmethods. Here we use the high-throughput Automatic-FLOW (AFLOW) method to study\nthe energetics of tin in multiple structures using a variety of density\nfunctionals. We look at the successes and deficiencies of each functional. As\nno functional is completely satisfactory, we look Hubbard U corrections and\nshow that the Coulomb interaction can be chosen to predict the correct phase\ntransition temperature. We also discuss the necessity of testing\nhigh-throughput calculations for convergence for systems with small energy\ndifferences.",
        "positive": "Enhanced magnetization in the multiferroic nanocomposites\n  Bi$_{0.9}$Gd$_{0.1}$Fe$_{0.9}$Mn$_{0.05}$X$_{0.05}$O$_3$ (X= Cr, Co) thin\n  films: In this work we elaborated and characterized nanocomposite thin films using a\npreselected multiferroic matrix Bi$_{0.9}$Gd$_{0.1}$Fe$_{0.9}$Mn$_{0.1}$O$_3$\n(BGFMO) in the aim to enhance their basic ferroelectric and magnetic\nproperties. The local ferroelectric character of these nanocomposites thin\nfilms was investigated by piezoresponse force microscopy (PFM). Switching\nbehavior for ferroelectric domains was probed by locally manipulating domains.\nThe magnetic investigation showed that the incorporation of transition metal\nelements in the BGFMO matrix brings out interesting increase in the macroscopic\nmagnetisation at room temperature. Moreover, a spin glass type behavior is\nobserved in M(T) curves for the studied thin films."
    },
    {
        "anchor": "Epitaxial Co-Deposition Growth of CaGe2 Films by Molecular Beam Epitaxy\n  for Large Area Germanane: Two-dimensional crystals are an important class of materials for novel\nphysics, chemistry, and engineering. Germanane (GeH), the germanium-based\nanalogue of graphane (CH), is of particular interest due to its direct band gap\nand spin-orbit coupling. Here, we report the successful co-deposition growth of\nCaGe2 films on Ge(111) substrates by molecular beam epitaxy (MBE) and their\nsubsequent conversion to germanane by immersion in hydrochloric acid. We find\nthat the growth of CaGe2 occurs within an adsorption-limited growth regime,\nwhich ensures stoichiometry of the film. We utilize in situ reflection high\nenergy electron diffraction (RHEED) to explore the growth temperature window\nand find the best RHEED patterns at 750 {\\deg}C. Finally, the CaGe2 films are\nimmersed in hydrochloric acid to convert the films to germanane. Auger electron\nspectroscopy of the resulting film indicates the removal of Ca and RHEED\npatterns indicate a single-crystal film with in-plane orientation dictated by\nthe underlying Ge(111) substrate. X-ray diffraction and Raman spectroscopy\nindicate that the resulting films are indeed germanane. Ex situ atomic force\nmicroscopy (AFM) shows that the grain size of the germanane is on the order of\na few micrometers, being primarily limited by terraces induced by the miscut of\nthe Ge substrate. Thus, optimization of the substrate could lead to the\nlong-term goal of large area germanane films.",
        "positive": "Topological phase transition and phonon-space Dirac topology surfaces in\n  ZrTe$_5$: We use first-principles methods to reveal that in ZrTe$_5$, a layered van der\nWaals material like graphite, atomic displacements corresponding to five of the\nsix zone-center A$_g$ (symmetry-preserving) phonon modes can drive a\ntopological phase transition from strong to weak topological insulator with a\nDirac semimetal state emerging at the transition, giving rise to a Dirac\ntopology surface in the multi-dimensional space formed by the A$_g$ phonon\nmodes. This implies that the topological phase transition in ZrTe$_5$ can be\nrealized with many different settings of external stimuli that are capable of\npenetrating through the phonon-space Dirac surface without breaking the\ncrystallographic symmetry. Furthermore, we predict that domains with effective\nmass of opposite signs can be created by laser pumping and will host Weyl modes\nof opposite chirality propagating along the domain boundaries. Studying\nphonon-space topology surfaces provides a new route to understanding and\nutilizing the exotic physical properties of ZrTe$_5$ and related quantum\nmaterials."
    },
    {
        "anchor": "Physics-based Constitutive Equation for Thermo-Chemical Aging in\n  Elastomers based on Crosslink Density Evolution: This paper presents a physics-based constitutive equation to predict the\nthermo-chemical aging in elastomers. High-temperature oxidation in elastomers\nis a complex phenomenon. The macromolecular network of elastomers'\nmicrostructures undergoes chain scission and crosslinking under high\ntemperature and oxygen diffusion conditions. In this work, we modify the\nnetwork stiffness and the chain extensibility in the Arruda-Boyce well-known\neight-chain constitutive equation to incorporate the additional Helmholtz free\nenergy due to network changes in elastomers' microstructures. The effect of\nnetwork evolution due to aging in changing the shear modulus and the number of\nchain monomers is considered. The modification is based on chemical\ncharacterization tests, namely the equilibrium swelling experiment to measure\nthe crosslink density evolution. The developed constitutive equation predicts\nthe mechanical responses of thermo-chemically aged elastomers independent of\nany mechanical tests on aged samples. The proposed constitutive equation is\nvalidated with respect to a comprehensive set of experimental data available in\nthe literature that were designed to capture thermo-chemical aging effects in\nelastomers. The comparison showed that the constitutive equation can accurately\npredict the intermittent tensile tests based on crosslink density evolution\ninput. The developed constitutive equation is physics-based, simple, and\nincludes minimal material parameters.",
        "positive": "Water-Gated Charge Doping of Graphene Induced by Mica Substrates: We report on the existence of water-gated charge doping of graphene deposited\non atomically flat mica substrates. Molecular films of water in units of ~0.4\nnm-thick bilayers were found to be present in regions of the interface of\ngraphene/mica hetero-stacks prepared by micromechanical exfoliation of kish\ngraphite. The spectral variation of the G and 2D bands, as visualized by Raman\nmapping, shows that mica substrates induce strong p-type doping in graphene,\nwith hole densities of $(9 \\pm 2) \\times 1012 cm${-2}$. The ultrathin water\nfilms, however, effectively block interfacial charge transfer, rendering\ngraphene significantly less hole-doped. Scanning Kelvin probe microscopy\nindependently confirmed a water-gated modulation of the Fermi level by 0.35 eV,\nin agreement with the optically determined hole density. The manipulation of\nthe electronic properties of graphene demonstrated in this study should serve\nas a useful tool in realizing future graphene applications."
    },
    {
        "anchor": "Moir\u00e9 pattern formation in epitaxial growth on a covalent substrate:\n  Sb on InSb(111)A: Structural moir\\'e superstructures arising from two competing lattices may\nlead to unexpected electronic behavior, such as superconductivity or Mottness.\nMost investigated moir\\'e heterostructures are based on van der Waals (vdW)\nmaterials, as strong interface interactions typically lead to the formation of\nstrained films or regular surface reconstructions. Here we successfully\nsynthesize ultrathin Sb films, that are predicted to show thickness-dependent\ntopological properties, on semi-insulating InSb(111)A. Despite the covalent\nnature of the substrate surface, we prove by scanning transmission electron\nmicroscopy (STEM) that already the first layer of Sb atoms grows completely\nunstrained, while azimuthally aligned. Rather than compensating the lattice\nmismatch of -6.4% by structural modifications, the Sb films form a pronounced\nmoir\\'e pattern as we evidence by scanning tunneling microscopy (STM)\ntopography up to film thicknesses of several bilayers. Our model calculations\nbased on density functional theory (DFT) assign the moir\\'e pattern to a\nperiodic surface corrugation. In agreement with DFT predictions, irrespective\nof the moir\\'e modulation, the topological surface state known on thick Sb film\nis experimentally confirmed to persist down to low film thicknesses, and the\nDirac point shifts towards lower binding energies with decreasing Sb thickness.",
        "positive": "Continuum mechanics of the interaction of phase boundaries and\n  dislocations in solids: The continuum mechanics of line defects representing singularities due to\nterminating discontinuities of the elastic displacement and its gradient field\nis developed. The development is intended for application to coupled phase\ntransformation, grain boundary, and plasticity-related phenomena at the level\nof individual line defects and domain walls. The continuously distributed\ndefect approach is developed as a generalization of the discrete, isolated\ndefect case. Constitutive guidance for equilibrium response and dissipative\ndriving forces respecting frame-indifference and non-negative mechanical\ndissipation is derived. A differential geometric interpretation of the defect\nkinematics is developed, and the relative simplicity of the actual adopted\nkinematics is pointed out. The kinematic structure of the theory strongly\npoints to the incompatibility of dissipation with strict deformation\ncompatibility."
    },
    {
        "anchor": "Machine Learning for the edge energies of high symmetry Au nanoparticles: We present data-driven simulations for gold nanostructures, and develop a\nmodel that links total energy to geometrical features of the particle, with the\nultimate goal of deriving reliable edge energies of gold. Assuming that the\ntotal energy can be decomposed into contributions from the bulk, surfaces,\nedges, and vertices, we use machine learning for reliable multi-variant fits of\nthe associated coefficients. The proposed method of total energy calculations\nusing machine learning produces almost ab-initio-like accuracy with minimal\ncomputational cost. Furthermore, a clear definition and metric for edge energy\nis introduced for edge-energy density calculations that avoid the troublesome\ndefinition of edge length in nanostructures. Our results for edge-energy\ndensity are 0.22 eV/{\\AA} for (100)/(100) edges and 0.20 eV/{\\AA} for\n(111)/(111) edges. Calculated vertex energies are about 1 eV/atom. The present\nmethod can be readily extended to other metals and edge orientations as well as\narbitrary nanoparticle shapes.",
        "positive": "Establishing the carrier scattering phase diagram for ZrNiSn-based\n  half-Heusler thermoelectric materials: Chemical doping is one of the most important strategies for tuning electrical\nproperties of semiconductors, particularly thermoelectric materials. Generally,\nthe main role of chemical doping lies in optimizing the carrier concentration,\nbut there can potentially be other important effects. Here, we show that\nchemical doping plays multiple roles for both electron and phonon transport\nproperties in half-Heusler thermoelectric materials. With ZrNiSn-based\nhalf-Heusler materials as an example, we use high-quality single and\npolycrystalline crystals, various probes, including electrical transport\nmeasurements, inelastic neutron scattering measurement, and first-principles\ncalculations, to investigate the underlying electron-phonon interaction. We\nfind that chemical doping brings strong screening effects to ionized\nimpurities, grain boundary, and polar optical phonon scattering, but has\nnegligible influence on lattice thermal conductivity. Furthermore, it is\npossible to establish a carrier scattering phase diagram, which can be used to\nselect reasonable strategies for optimization of the thermoelectric\nperformance."
    },
    {
        "anchor": "Tuning phase-stability and short-range order through Al-doping in\n  (CoCrFeMn)100-xAlx high entropy alloys: For (CoCrFeMn)$_{100-x}$Al$_{x}$ high-entropy alloys, we investigate the\nphase evolution with increasing Al-content (0 $\\le$ x $\\le$ 20 at.%). From\nfirst-principles theory, the Al-doping drives the alloy structurally from FCC\nto BCC separated by a narrow two-phase region (FCC+BCC), which is well\nsupported by our experiments. We highlight the effect of Al-doping on the\nformation enthalpy and electronic structure of (CoCrFeMn)$_{100-x}$Al$_{x}$\nalloys. As chemical short-range order (SRO) in multicomponent alloys indicates\nthe nascent local order (and entropy changes), as well as expected\nlow-temperature ordering behavior, we use thermodynamic linear-response within\ndensity-functional theory to predict SRO and ordering transformation and\ntemperatures inherent in (CoCrFeMn)$_{100-x}$Al$_{x}$. The predictions agree\nwith our present experimental findings, and other reported ones.",
        "positive": "Response to David Steigmann's discussion of our paper: We respond to David Steigmann's discussion of our paper \"A general theory for\nanisotropic Kirchhoff-Love shells with in-plane bending of embedded fibers,\nMath. Mech. Solids, 28(5):1274-1317\" (arXiv:2101.03122). His discussion allows\nus to clarify two misleading statements in our original paper, and confirm that\nits formulation is fully consistent with the formulation of Steigmann. We also\ndemonstrate that some of our original statements criticized by Steigmann are\nnot wrong."
    },
    {
        "anchor": "First Principles Validation of Energy Barriers in Ni$_{75}$Al$_{25}$: Precipitates in Nickel-based superalloys form during heat treatment on a time\nscale inaccessible to direct molecular dynamics simulation, but could be\nstudied using kinetic Monte Carlo (KMC). This requires reliable values for the\nbarrier energies separating distinct configurations over the trajectory of the\nsystem. In this study, we validate vacancy migration barriers found with the\nActivation-Relaxation Technique nouveau (ARTn) method in partially ordered\nNi$_{75}$Al$_{25}$ with a monovacancy using published potentials for the atomic\ninteractions against first-principles methods. In a first step, we confirm that\nthe ARTn barrier energies agree with those determined with the nudged elastic\nband (NEB) method. As the number of atoms used in those calculations is too\ngreat for direct ab initio calculations, we then cut the cell size to 255\natoms, thus controlling finite size effects. We then use the plane-wave density\nfunctional theory (DFT) code CASTEP and its inbuilt NEB method in the smaller\ncells. This provides us with a continuous validation chain from first\nprinciples to kinetic Monte Carlo simulations with interatomic potentials. We\nthen evaluate the barrier energies of five further interatomic potentials with\nNEB, demonstrating that none yields these with sufficient reliability for KMC\nsimulations, with some of them failing completely. This is a first step towards\nquantifying the errors incurred in KMC simulations of precipitate formation and\nevolution.",
        "positive": "Universal mobility characteristics of graphene originating from\n  electron/hole scattering by ionised impurities: Pristine graphene and graphene-based heterostructures exhibit exceptionally\nhigh electron mobility and conductance if their surface contains few\nelectron-scattering impurities. Here, we reveal a universal connection between\ngraphene's carrier mobility and the variation of its electrical conductance\nwith carrier density. Our model of graphene conductivity is based on a\nconvolution of carrier density and its uncertainty, which reproduces the\nobserved universality. Taking a single conductance measurement as input, this\nmodel accurately predicts the full shape of the conductance versus carrier\ndensity curves for a wide range of reported graphene samples. We verify the\nconvolution model by numerically solving the Boltzmann transport equation to\nanalyse in detail the effects of charged impurity scattering on carrier\nmobility. In this model, we also include optical phonons, which relax\nhigh-energy charge carriers for small impurity densities. Our numerical and\nanalytical results both capture the universality observed in experiment and\nprovide a way to estimate all key transport parameters of graphene devices. Our\nresults demonstrate how the carrier mobility can be predicted and controlled,\nthereby providing insights for engineering the properties of 2D materials and\nheterostructures."
    },
    {
        "anchor": "LAMMPS Implementation of Rapid Artificial Neural Network Derived\n  Interatomic Potentials: While machine learning approaches have been successfully used to represent\ninteratomic potentials, their speed has typically lagged behind conventional\nformalisms. This is often due to the complexity of the structural fingerprints\nused to describe the local atomic environment and the large cutoff radii and\nneighbor lists used in the calculation of these fingerprints. Even recent\nmachine learned methods are at least 10 times slower than traditional\nformalisms. An implementation of a rapid artificial neural network (RANN) style\npotential in the LAMMPS molecular dynamics package is presented here which\nutilizes angular screening to reduce computational complexity without reducing\naccuracy. For the smallest neural network architectures, this formalism rivals\nthe modified embedded atom method (MEAM) for speed and accuracy, while the\nnetworks approximately one third as fast as MEAM were capable of reproducing\nthe training database with chemical accuracy. The numerical accuracy of the\nLAMMPS implementation is assessed by verifying conservation of energy and\nagreement between calculated forces and pressures and the observed derivatives\nof the energy as well as by assessing the stability of the potential in dynamic\nsimulation. The potential style is tested using a force field for magnesium and\nthe computational efficiency for a variety of architectures is compared to a\ntraditional potential models as well as alternative ANN formalisms. The\npredictive accuracy is found to rival that of slower methods.",
        "positive": "Phonon-assisted magnetic Mott-insulating state in the charge density\n  wave phase of single-layer 1TNbSe2: We study the structural, electronic and vibrational properties of\nsingle-layer 1TNbSe$_2$ from first principles. Within the generalized gradient\napproximation, the 1T polytype is highly unstable with respect to the 2H. The\nDFT+U method improves the stability of the 1T phase, explaining its detection\nin experiments. A charge density wave occurs with a\n$\\sqrt{13}\\times\\sqrt{13}~R30^{\\circ}$ periodicity, in agreement with STM data.\nAt $U=0$, the David-star reconstruction displays a flat band below the Fermi\nlevel with a marked d$_{z^2-r^2}$ orbital character of the central Nb. The\nHubbard interaction induces a magnetic Mott insulating state. Magnetism\ndistorts the lattice around the central Nb atom in the star, reduces the\nhybridization between the central Nb d$_{z^2-r^2}$ orbital and the neighbouring\nSe p-states and lifts in energy the flat band becoming non-bonding. This\ncooperative lattice and magnetic effect amplifies the Mott gap. Single-layer\n1TNbSe$_2$ is then a phonon-assisted spin-$1/2$ Magnetic Mott insulator."
    },
    {
        "anchor": "Rotational dynamics and polymerization of C$_{60}$ in C$_{60}$-cubane\n  crystals: A molecular dynamics study: We report classical and tight-binding molecular dynamics simulations of the\nC$_{60}$ fullerene and cubane molecular crystal in order to investigate\nintermolecular dynamics and polymerization processes. Our results show that,\nfor 200 K and 400 K, cubane molecules remain basically fixed, presenting only\nthermal vibrations, while C$_{60}$ fullerenes show rotational motions.\nFullerenes perform \"free\" rotational motions at short times ($\\lesssim$ 1 ps),\nsmall amplitude hindered rotational motions (librations) at intermediate times,\nand rotational diffusive dynamics at long times ($\\gtrsim$ 10 ps). The\nmechanisms underlying these dynamics are presented. Random copolymerization\namong cubanes and fullerenes were observed when temperature is increased,\nleading to the formation of a disordered structure. Changes in the radial\ndistribution function and electronic density of states indicate the coexistence\nof amorphous and crystalline phases. The different conformational phases that\ncubanes and fullerenes undergo during the copolymerization process are\ndiscussed.",
        "positive": "Impurity Band Conduction in Si-doped \\b{eta}-Ga2O3 Films: By combining temperature-dependent resistivity and Hall effect measurements,\nwe investigate donor state energy in Si-doped \\b{eta}-Ga2O3 films grown using\nmetal-organic vapor phase epitaxy (MOVPE). High magnetic field Hall effect\nmeasurements (H = +/-90 kOe) showed non-linear Hall resistance for T < 150 K\nrevealing two-band conduction. Further analyses revealed carrier freeze-out\ncharacteristics in both bands yielding donor state energies of ~ 33.7 and ~\n45.6 meV. The former is consistent with the donor energy of Si in \\b{eta}-Ga2O3\nwhereas the latter suggests a residual donor state, likely associated with a DX\ncenter. This study provides a critical insight into the impurity band\nconduction and the defect energy states in \\b{eta}-Ga2O3 using high-field\nmagnetotransport measurements."
    },
    {
        "anchor": "First-Principles Modeling of Ferroelectric Oxide Nanostructures: The aim of this Chapter is to provide an account of recent advances in the\nfirst-principles modeling of ferroelectric oxide nanostructures. Starting from\na microscopic description of ferroelectricity in bulk materials and considering\nthen, successively, different kinds of nanostructures (films, multilayers,\nwires, and particles), we try to identify the main trends and to provide a\ncoherent picture of the role of finite size effects in ferroelectric oxides.",
        "positive": "First-principles derivation of elastic interaction between Jahn-Teller\n  centers in crystals via lattice Green's functions: Jahn-Teller (JT) systems with strong and intermediate vibronic coupling are\ndescribed in terms of local JT active vibrational modes. In JT crystals, the\nelastic interaction of these modes at different JT centers plays a crucial\nrole, for instance, in determining critical temperature of structural phase\ntransitions. Despite their importance, the parameters of elastic interaction\nbetween JT centers have not been accessed yet by first-principles calculations.\nIn this paper, we develop an effective Hamiltonian methodology for the thorough\ndescription of the elastic interactions in cooperative Jahn-Teller problems,\nwhich treats the interactions with both phonons and uniform strains. All the\nmicroscopic parameters, such as lattice Green's functions, elastic modulus, can\nbe obtained or calculated based on first-principles the calculation. The method\nhas been applied to a series of 5d1 double perovskites. Such effective\nHamiltonian methodology can be, in general, used to investigate the APES of any\ntype of the local distortions, such as impurities, defects, etc."
    },
    {
        "anchor": "Anisotropy induced spin re-orientation in chemically-modulated amorphous\n  ferrimagnetic films: The ability to tune the competition between the in-plane and out-of-plane\norientation of magnetization provides a means to construct thermal sensors with\na sharp spin re-orientation transition at specific temperatures. We have\nobserved such a tuneable, temperature driven spin re-orientation in\nstructurally amorphous, ferrimagnetic rare earth-transition metal (RE-TM) alloy\nthin films using scanning transmission X-ray microscopy (STXM) and magnetic\nmeasurements. The nature of the spin re-orientation transition in FeGd can be\nfully explained by a non-equilibrium, nanoscale modulation of the chemical\ncomposition of the films. This modulation leads to a magnetic domain pattern of\nnanoscale speckles superimposed on a background of in-plane domains that form\nLaudau configurations in micron-scale patterned elements. It is this speckle\nmagnetic structure that gives rise to a sharp two step-reversal mechanism that\nis temperature dependent. The possibility to balance competing anisotropies\nthrough the temperature opens opportunities to create and manipulate\ntopological spin textures.",
        "positive": "Dirac fermions in borophene: Honeycomb structures of group IV elements can host massless Dirac fermions\nwith non-trivial Berry phases. Their potential for electronic applications has\nattracted great interest and spurred a broad search for new Dirac materials\nespecially in monolayer structures. We present a detailed investigation of the\n\\beta 12 boron sheet, which is a borophene structure that can form\nspontaneously on a Ag(111) surface. Our tight-binding analysis revealed that\nthe lattice of the \\beta 12-sheet could be decomposed into two triangular\nsublattices in a way similar to that for a honeycomb lattice, thereby hosting\nDirac cones. Furthermore, each Dirac cone could be split by introducing\nperiodic perturbations representing overlayer-substrate interactions. These\nunusual electronic structures were confirmed by angle-resolved photoemission\nspectroscopy and validated by first-principles calculations. Our results\nsuggest monolayer boron as a new platform for realizing novel high-speed\nlow-dissipation devices."
    },
    {
        "anchor": "Electron-Ion Structure Factors and the General Accuracy of Linear\n  Response: We show that electron-ion structure factors in fluid metallic systems can be\nwell understood from an application of linear response in the electron system,\ncombined with hard-sphere like correlation for the ionic component. In\nparticular, we predict that electron-ion structure factors fall into two\ngeneral classes, one for high ($Z>3$) and one for low ($Z\\leq2$) valence\nmetals, and make suggestions for experiments to test these ideas. In addition,\nwe show how the general success of electronic linear response for most metallic\nsystems stems in part from an intrinsic interference between atomic and\nelectronic length scales which weakens the nonlinear response. The main\nexception to this is metallic hydrogen.",
        "positive": "Rare-earth free yellow-green emitting NaZnPO4:Mn phosphor for lighting\n  applications: Manganese doped sodium zinc phosphate phosphor with exceptional features\nhaving ultra-violet (UV) to visible absorption (300-470 nm), yellow-green (~543\nnm) broad-band photoluminescence (PL) and appreciable color co-ordinates\n(x=0.39, y=0.58) is reported. It has a crystal structure consists of discrete\nPO4 tetrahedra linked by ZnO4 and NaO4 distorted tetrahedral such that three\ntetrahedra, one of each kind, share one corner. The presence of UV sensitive\nZn-O-Zn bonds efficient energy transfer to Mn2+ ions resulted in brightest PL\nand external quantum yield of 63% at 418 nm. Our experiment demonstrated the\npossibility of producing inexpensive white-light emitting devices for future."
    },
    {
        "anchor": "Smooth, homogeneous, high-purity Nb3Sn superconducting RF resonant\n  cavity by seed-free electrochemical synthesis: Workbench-size particle accelerators, enabled by Nb3Sn-based superconducting\nradio-frequency (SRF) cavities, hold the potential of driving scientific\ndiscovery by offering a widely accessible and affordable source of high-energy\nelectrons and X-rays. Thin-film Nb3Sn RF superconductors with high quality\nfactors, high operation temperatures, and high-field potentials are critical\nfor these devices. However, surface roughness, non-stoichiometry, and\nimpurities in Nb3Sn deposited by conventional Sn-vapor diffusion prevent them\nfrom reaching their theoretical capabilities. Here we demonstrate a seed-free\nelectrochemical synthesis that pushes the limit of chemical and physical\nproperties in Nb3Sn. Utilization of electrochemical Sn pre-deposits reduces the\nroughness of converted Nb3Sn by five times compared to typical vapor-diffused\nNb3Sn. Quantitative mappings using chemical and atomic probes confirm improved\nstoichiometry and minimized impurity concentrations in electrochemically\nsynthesized Nb3Sn. We have successfully applied this Nb3Sn to the large-scale\n1.3 GHz SRF cavity and demonstrated ultra-low BCS surface resistances at\nmultiple operation temperatures, notably lower than vapor-diffused cavities.\nOur smooth, homogeneous, high-purity Nb3Sn provides the route toward high\nefficiency and high fields for SRF applications under helium-free cryogenic\noperations.",
        "positive": "Simulation of Magnetization Switching in Biaxial Single-Domain\n  Ferromagnetic Particles: The magnetization switching dynamics of biaxial single-domain homogeneous\nferromagnetic particles, in which the two easy axes are perpendicular to each\nother, is simulated using a 4-state clock model. A zero-field mapping of the\nstatics between the symmetric 4-state clock model and two decoupled Ising\nmodels is extended to non-zero field statics and to the dynamics. This\nsignificantly simplifies the analysis of the simulation results. We measure the\nmagnetization switching time of the model and analyze the results using droplet\ntheory. The switching dynamics in the asymmetric model is more complicated. If\nthe easy axis is perpendicular to the stable magnetization direction, the\nsystem can switch its magnetization via two different channels, one very fast\nand the other very slow. A maximum value for the switching field as a function\nof system size is obtained. The asymmetry affects the switching fields\ndifferently, depending on whether the switching involves one single droplet or\nmany droplets of spins in the stable magnetization configuration. The angular\ndependence of the switching field in symmetric and asymmetric models is also\nstudied."
    },
    {
        "anchor": "Electron-hole versus exciton delocalization in conjugated polymers: the\n  role of topology: There is currently a great need for solid state lasers that emit in the\ninfrared. Whether or not conjugated polymers that emit in the IR can be\nsynthesized is an interesting theoretical challenge. We show that the\nrequirement for such a material is that the exciton delocalization in the\nsystem be large, such that the optical gap is small. We develop a theory of\nexciton delocalization in conjugated polymers, and show that the extent of this\ncan be predicted from the topology of the conjugated polymer in question. We\ndetermine the precise structural characteristics that would be necessary for\nlight emission in the IR.",
        "positive": "BaTiO3 thin films as transitional ferrroelectrics with giant dielectric\n  response: Proximity to phase transitions (PTs) is frequently responsible for the\nlargest dielectric susceptibilities in ferroelectrics. The impracticality of\nusing temperature as a control parameter to reach those large responses has\nmotivated the design of solid solutions with phase boundaries between different\npolar phases at temperatures (typically room temperature) significantly lower\nthan the paraelectric-ferroelectric critical temperature. The flat energy\nlandscapes close to these PTs give rise to polarization rotation under external\nstimuli, being responsible for the best piezoelectrics so far and a their huge\nmarket. But this approach requires complex chemistry to achieve\ntemperature-independent PT boundaries and often involves lead-containing\ncompounds. Here we report that such a bridging state is possible in thin films\nof chemically simple materials such as BaTiO3. A coexistence of tetragonal,\northorhombic and their bridging low-symmetry phases are shown to be responsible\nfor the continuous vertical polarization rotation, recreating a smear\nin-transition state and leading to giant temperature-independent dielectric\nresponse. These features are distinct from those of single crystals,\nmulti-domain crystals, ceramics or relaxor ferroelectrics, requiring a\ndifferent description. We believe that other materials can be engineered in a\nsimilar way to form a class of ferroelectrics, in which MPB solid solutions are\nalso included, that we propose to coin as transitional ferroelectrics."
    },
    {
        "anchor": "First-principles prediction of structural, magnetic properties of\n  Cr-substituted strontium hexaferrite, and its site preference: To investigate the structural and magnetic properties of Cr-doped M-type\nstrontium hexaferrite (SrFe$_{12}$O$_{19}$) with x = (0.0, 0.5, 1.0), we\nperform first-principles total-energy calculations relied on density functional\ntheory. Based on the calculation of the substitution energy of Cr in strontium\nhexaferrite and formation probability analysis, we conclude that the doped Cr\natoms prefer to occupy the 2a, 12k, and 4f$_{2}$ sites which is in good\nagreement with the experimental findings. Due to Cr$^{3+}$ ion moment, 3\n{$\\mu_B$}, smaller than that of Fe$^{3+}$ ion, 5 {$\\mu_B$}, saturation\nmagnetization (M$_{s}$) reduce rapidly as the concentration of Cr increases in\nstrontium hexaferrite. The magnetic anisotropic field $\\left(H_{a}\\right)$\nrises with an increasing fraction of Cr despite a significant reduction of\nmagnetization and a slight increase of magnetocrystalline anisotropy\n$\\left(K_{1}\\right)$.The cause for the rise in magnetic anisotropy field\n$\\left(H_{a}\\right)$ with an increasing fraction of Cr is further emphasized by\nour formation probability study. Cr$^{3+}$ ions prefer to occupy the 2a sites\nat lower temperatures, but as the temperature rises, it is more likely that\nthey will occupy the 12k site. Cr$^{3+}$ ions are more likely to occupy the 12k\nsite than the 2a site at a specific annealing temperature (>700{\\deg}C).",
        "positive": "Observation of a Mott insulating ground state for Sn/Ge(111) at low\n  temperature: We report an investigation on the properties of 0.33 ML of Sn on Ge(111) at\ntemperatures down to 5 K. Low-energy electron diffraction and scanning\ntunneling microscopy show that the (3x3) phase formed at 200 K, reverts to a\nnew (root-3xroot-3)R30 phase below 30 K. The vertical distortion characteristic\nof the (3x3) phase is lost across the phase transition. Angle-resolved\nphotoemission experiments show that concomitantly with the structural phase\ntransition, a metal-insulator phase transition takes place. In agreement with\ntheoretical predictions, the (root-3xroot-3)R30 ground state is interpreted as\nthe experimental realization of a Mott insulator for a narrow half-filled band\nin a two-dimensional triangular lattice."
    },
    {
        "anchor": "Low temperature phase diagram of hydrogen at pressures up to 380 GPa. A\n  possible metallic phase at 360 GPa and 200 K: Two new phases of hydrogen have been discovered at room temperature in Ref.1:\nphase IV above 220 GPa and phase V above ~270 GPa. In the present work we have\nfound a new phase VI at P~360 GPa and T<200 K. This phase is likely metallic as\nfollows from the featureless Raman spectra, a strong drop in resistance, and\nabsence of a photoconductive response. We studied hydrogen at low temperatures\nwith the aid of Raman, infrared absorption, and electrical measurements at\npressures up to 380 GPa, and have built a new phase diagram of hydrogen.",
        "positive": "Hybrid density functional theory study on zinc blende GaN and diamond\n  surfaces and interfaces: Effects of size, hydrogen passivation and dipole\n  corrections: GaN based high electron mobility transistors show promise in numerous device\napplications which elicits the need for accurate models of bulk, surface, and\ninterface electronic properties. We detail here a hybrid density functional\ntheory study of zinc blende (zb) GaN and diamond bulk and surface properties,\nand zb GaN on diamond interfaces using slab supercell models. Details are\nprovided on the dependence of electronic properties with respect to supercell\nsize, the use of pseudo-hydrogen to passivate the bottom GaN layer, and dipole\ncorrections. The large bulk modulus of diamond provides a templating structure\nfor GaN to grow upon, where a large lattice mismatch is accounted for through\nthe inclusion of a cationic Ga adlayer. Looking at both type I and II surfaces\nand interfaces of GaN shows the instability of zb GaN without an adlayer (type\nII), where increased size, pseudo-hydrogen passivation and dipole corrections\ndo not remove the spurious interaction between the top and bottom layers in\ntype II GaN. Layer dependent density of states, local potential differences,\nand charge density differences show that the type I interface (with a Ga\nadlayer) is stable with an adhesion energy of 0.704 eV/{\\AA}2 (4.346 J/m2);\ninterestingly, the diamond charge density intercalates into the first layer of\nGaN, which was seen experimentally for wurtzite GaN grown over diamond. The\ntype II interface is shown to be unstable which implies that, to form a stable,\nthin-film zb interface between GaN and diamond, the partial pressure of\ntrimethylgallium must be controlled to ensure a Ga layer exists both on the top\nand bottom layer of the GaN thin film atop the diamond. We believe our results\ncan shed light towards a better understanding of the GaN/diamond multifaceted\ninterface present in the GaN overgrowth on diamond samples."
    },
    {
        "anchor": "The dynamics of amplified spontaneous emission in CdSe/ZnSe quantum dots: We have used the variable stripe technique and pump-probe spectroscopy to\ninvestigate both gain and the dynamics of amplified spontaneous emission from\nCdSe quantum dot structures. We have found modal gain coefficients of 75 and 32\n1/cm for asymmetric and symmetric waveguide structures, respectively. Amplified\nspontaneous emission decay times of 150 and 300 ps and carrier capture times of\n15 and 40 ps were measured for the structures with high and low material gains\nrespectively. The difference in the capture times are related to the fact that\nfor the symmetric waveguide, carriers diffuse into the active region from the\nuppermost ZnMgSSe cladding layer, yielding a longer rise time for the\npump-probe signals for this sample.",
        "positive": "Pressure effects on the magnetic structure in La0.5Ca0.5-xSrxMnO3 (0.1\n  -< x -< 0.4) manganites: The effect of high pressure (0 - 8 GPa) on the magnetic structure of\npolycrystalline samples of La0.5Ca0.5-xSrxMnO3 (0.1 -< x -< 0.4) manganites at\n5 K is investigated using neutron diffraction technique. Application of\npressure is found to modify the previously reported magnetic structure,\nobserved under ambient conditions, in these compounds [I. Dhiman et al., Phys.\nRev. B 77, 094440 (2008)]. In x = 0.1 composition, at 4.6(2) GPa and beyond,\nA-type antiferromagnetic structure is found to coexist with CE-type\nantiferromagnetic phase, observed at ambient pressure, with TN ~ 150 K. For x =\n0.3 sample, as a function of pressure the CE-type phase is fully suppressed at\n2.3(1) GPa and A-type antiferromagnetic phase is favored. Further Sr doping at\nx = 0.4, the A-type antiferromagnetic phase is observed at ambient pressure and\nfor T < TN (~ 250K). This phase is retained in the studied pressure range.\nHowever, the magnetic moment progressively reduces with increasing pressure,\nindicating the suppression of A-type antiferromagnetic phase. The present study\nbrings out the fragile nature of the CE-type antiferromagnetic state in half\ndoped manganites as a function of pressure and disorder \\sigma 2. We observe\nthat pressure required for destabilizing the CE-type antiferromagnetic state is\nreduced with increasing disorder \\sigma 2. External pressure and changing\nA-site ionic radii have analogous effect on the magnetic structure."
    },
    {
        "anchor": "Hybrid density functional study of electronic and optical properties of\n  phase change memory material: $\\mathrm{Ge_{2}Sb_{2}Te_{5}}$: In this article, we use hybrid density functional (HSE06) to study the\ncrystal and electronic structures and optical properties of well known phase\nchange memory material $\\mathrm{Ge_{2}Sb_{2}Te_{5}}$. We calculate the\nstructural parameters, band gaps and dielectric functions of three stable\nstructures of this material. We also analyze the electron charge distribution\nusing the Bader's theory of charge analysis. We find that hybrid density\nfunctional slightly overestimate the value of 'C' parameter. However, overall,\nour results calculated with the use of hybrid density functional (HSE06) are\nvery close to available experimental values than calculated with the use of PBE\nfunctional. Specifically, the electronic band gap values of this material\ncalculated with HSE06 are in good agreement with the available experimental\ndata in the literature. Furthermore, we perform the charge analysis and find\nthat naive ionic model fails to explain the charge distribution between the\nconstituent atoms, showing the complex nature of this compound.",
        "positive": "Particle-Level Modeling of the Charge-Discharge Behavior of\n  Nanoparticulate Phase-Separating Li-Ion Battery Electrodes: In nanoparticulate phase-separating electrodes, phase separation inside the\nparticles can be hindered during their charge/discharge cycles even when a\nthermodynamic driving force for phase separation exists. In such cases,\nparticles may (de)lithiate discretely in a process referred to as mosaic\ninstability. This instability could be the key to elucidating the complex\ncharge/discharge dynamics in nanoparticulate phase-separating electrodes. In\nthis paper, the dynamics of the mosaic instability is studied using Smoothed\nBoundary Method simulations at the particle level, where the concentration and\nelectrostatic potential fields are spatially resolved around individual\nparticles. Two sets of configurations consisting of spherical particles with an\nidentical radius are employed to study the instability in detail. The effect of\nan activity-dependent exchange current density on the mosaic instability, which\nleads to asymmetric charge/discharge, is also studied. While we show that our\nmodel reproduces the results of a porous-electrode model for the simple setup\nstudied here, it is a powerful framework with the capability to predict the\ndetailed dynamics in three-dimensional complex electrodes and provides further\ninsights into the complex dynamics that result from the coupling of\nelectrochemistry, thermodynamics, and transport kinetics."
    },
    {
        "anchor": "Influence of Charge Carrier Mobility on the Performance of Organic Solar\n  Cells: The power conversion efficiency of organic solar cells based on\ndonor--acceptor blends is governed by an interplay of polaron pair dissociation\nand bimolecular polaron recombination. Both processes are strongly dependent on\nthe charge carrier mobility, the dissociation increasing with faster charge\ntransport, with raised recombination losses at the same time. Using a\nmacroscopic effective medium simulation, we calculate the optimum charge\ncarrier mobility for the highest power conversion efficiency, for the first\ntime accounting for injection barriers and a reduced Langevin-type\nrecombination. An enhancement of the charge carrier mobility from\n$10^{-8}$m$^2$/Vs for state of the art polymer:fullerene solar cells to about\n$10^{-6}$m$^2$/Vs, which yields the maximum efficiency, corresponds to an\nimprovement of only about 20% for the given parameter set.",
        "positive": "Neutral and charged excitations in carbon fullerenes from\n  first-principles many-body theories: We investigate the accuracy of first-principles many-body theories at the\nnanoscale by comparing the low energy excitations of the carbon fullerenes\nC_20, C_24, C_50, C_60, C_70, and C_80 with experiment. Properties are\ncalculated via the GW-Bethe-Salpeter Equation (GW-BSE) and diffusion Quantum\nMonte Carlo (QMC) methods. We critically compare these theories and assess\ntheir accuracy against available photoabsorption and photoelectron spectroscopy\ndata. The first ionization potentials are consistently well reproduced and are\nsimilar for all the fullerenes and methods studied. The electron affinities and\nfirst triplet excitation energies show substantial method and geometry\ndependence. These results establish the validity of many-body theories as\nviable alternative to density-functional theory in describing electronic\nproperties of confined carbon nanostructures. We find a correlation between\nenergy gap and stability of fullerenes. We also find that the electron affinity\nof fullerenes is very high and size-independent, which explains their tendency\nto form compounds with electron-donor cations."
    },
    {
        "anchor": "Monolayer RhB4: half-auxeticity and almost ideal spin-orbit Dirac point\n  semimetal: Structural-property relationship, the connection between materials'\nstructures and their properties, is central to the materials research.\nEspecially at reduced dimensions, novel structural motifs often generate unique\nphysical properties.Motivated by a recent work reporting a novel half auxetic\neffect in monolayer PdB4 with a hypercoordinated structure, here, we\nextensively explore similar 2D transition metal boride structures MB4 with M\ncovering 3d and 4d elements.Our investigation screens out one stable candidate,\nthe monolayer RhB4. We find that monolayer RhB4 also shows half auxeticity,\ni.e., the material always expands in a lateral in-plane direction in response\nto an applied strain in the other direction, regardless of whether the strain\nis positive or negative.We show that this special mechanical character is\nintimately tied to the hypercoordinated structure with the M\\c{opyright}B8\nstructural motif. Furthermore, regarding electronic properties, monolayer RhB4\nis found to be the first example of an almost ideal 2D spin-orbit Dirac point\nsemimetal.The low-energy band structure is clean, with a pair of fourfold\ndegenerate Dirac points robust under spin-orbit coupling located close to the\nFermi level. These Dirac points are enforced by the nonsymmorphic space group\nsymmetry which is also determined by the lattice structure. Our work deepens\nthe fundamental understanding of structural-property relationship in reduced\ndimensions. The half auxeticity and the spin-orbit Dirac points will make\nmonolayer RhB4 a promising platform for nanomechanics and nanoelectronics\napplications.",
        "positive": "Excitons versus electron-hole plasma in monolayer transition metal\n  dichalcogenide semiconductors: When electron-hole pairs are excited in a semiconductor, it is a priori not\nclear if they form a fermionic plasma of unbound particles or a bosonic exciton\ngas. Usually, the exciton phase is associated with low temperatures. In\natomically thin transition metal dichalcogenide semiconductors, excitons are\nparticularly important even at room temperature due to strong Coulomb\ninteraction and a large exciton density of states. Using state-of-the-art\nmany-body theory including dynamical screening, we show that the\nexciton-to-plasma ratio can be efficiently tuned by dielectric substrate\nscreening as well as charge carrier doping. Moreover, we predict a Mott\ntransition from the exciton-dominated regime to a fully ionized electron-hole\nplasma at excitation densities between $3\\times10^{12}$ cm$^{-2}$ and\n$1\\times10^{13}$ cm$^{-2}$ depending on temperature, carrier doping and\ndielectric environment. We propose the observation of these effects by studying\nexcitonic satellites in photoemission spectroscopy and scanning tunneling\nmicroscopy."
    },
    {
        "anchor": "Band structure engineering in (Bi1-xSbx)2Te3 ternary topological\n  insulators: Three-dimensional (3D) topological insulators (TI) are novel quantum\nmaterials with insulating bulk and topologically protected metallic surfaces\nwith Dirac-like band structure. The spin-helical Dirac surface states are\nexpected to host exotic topological quantum effects and find applications in\nspintronics and quantum computation. The experimental realization of these\nideas requires fabrication of versatile devices based on bulk-insulating TIs\nwith tunable surface states. The main challenge facing the current TI materials\nexemplified by Bi2Se3 and Bi2Te3 is the significant bulk conduction, which\nremains unsolved despite extensive efforts involving nanostructuring, chemical\ndoping and electrical gating. Here we report a novel approach for engineering\nthe band structure of TIs by molecular beam epitaxy (MBE) growth of\n(Bi1-xSbx)2Te3 ternary compounds. Angle-resolved photoemission spectroscopy\n(ARPES) and transport measurements show that the topological surface states\nexist over the entire composition range of (Bi1-xSbx)2Te3 (x = 0 to 1),\nindicating the robustness of bulk Z2 topology. Most remarkably, the systematic\nband engineering leads to ideal TIs with truly insulating bulk and tunable\nsurface state across the Dirac point that behave like one quarter of graphene.\nThis work demonstrates a new route to achieving intrinsic quantum transport of\nthe topological surface states and designing conceptually new TI devices with\nwell-established semiconductor technology.",
        "positive": "Effect of Size Dispersity On the Melting Transition: We present a molecular dynamics simulation study of the liquid-solid\ntransition in a two dimensional system consisting of particles of two different\nsizes interacting via a truncated Lennard-Jones potential. We work with equal\nnumber of particles of each kind and the dispersity $\\Delta$ in the sizes of\nthe particles is varied by changing the ratio of the particle sizes only. For\nthe monodisperse case ($\\Delta = 0$) and for small values of $\\Delta$, we find\na first order liquid-solid transition on increasing the volume fraction $\\rho$\nof the particles . As we increase $\\Delta$, the first-order transition\ncoexistence region weakens gradually and completely disappears at high\ndispersities around $\\Delta = 0.10$ . At these values of dispersity the high\ndensity phase lacks long range translational order but possesses orientational\norder with a large but finite correlation length. The consequences of this\neffect of dispersity on the glass transition and on the melting transition in\ngeneral are discussed."
    },
    {
        "anchor": "Role of Water Molecule in Enhancing the Proton Conductivity on Graphene\n  Oxide at Humidity Condition: Recent experimental reports on in-plane proton conduction in reduced graphene\noxide (rGO) films open a new way for the design of proton exchange membrane\nessential in fuel cells and chemical filters. At high humidity condition, water\nmolecules attached on the rGO sheet are expected to play a critical role, but\ntheoretical works for such phenomena have been scarcely found in the\nliterature. In this study, we investigate the proton migration on\nwater-adsorbed monolayer and bilayer rGO sheets using first-principles\ncalculations in order to reveal the mechanism. We devise a series of models for\nthe water-adsorbed rGO films as systematically varying the reduction degree and\nwater content, and optimize their atomic structures in reasonable agreement\nwith the experiment, using a density functional that accounts for van der Waals\ncorrection. Upon suggesting two different transport mechanisms, epoxy-mediated\nand water-mediated hoppings, we determine the kinetic activation barriers for\nthese in-plane proton transports on the rGO sheets. Our calculations indicate\nthat the water-mediated transport is more likely to occur due to its much lower\nactivation energy than the epoxy-mediated one and reveal new prospects for\ndeveloping efficient solid proton conductors.",
        "positive": "Strain analysis of multiferroic BiFeO3-CoFe2O4 nanostructures by Raman\n  scattering: We report a Raman scattering investigation of columnar BiFeO3-CoFe2O4\n(BFO-CFO) epitaxial thin film nanostructures, where BFO pillars are embedded in\na CFO matrix. The feasibility of a strain analysis is illustrated through an\ninvestigation of two nanostructures with different BFO-CFO ratios. We show that\nthe CFO matrix presents the same strain state in both nanostructures, while the\nstrain state of the BFO pillars depends on the BFO/CFO ratio with an increasing\ntensile strain along the out-of-plane direction with decreasing BFO content.\nOur results demonstrate that Raman scattering allows monitoring strain states\nin complex 3D multiferroic pillar/matrix composites."
    },
    {
        "anchor": "Oxygen vacancy-induced structural evolution of SrFeO$_{3-x}$ epitaxial\n  thin film from brownmillerite to perovskite: We investigated SrFeO$_{3-x}$ thin films on a SrTiO$_3$ (001) substrate\nprepared via pulsed laser epitaxy using an optical spectroscopy technique. The\noxygen vacancy level ($x$) was controlled by post-annealing processes at\ndifferent oxygen partial pressures. We achieved a brownmillerite(BM) structure\nat $x =$ 0.5 and observed the evolution of the crystal structure from BM into\nperovskite(PV) as the oxygen concentration increased. We observed the evolution\nof infrared-active phonons with respect to the oxygen concentration, which was\nclosely related to the structural evolution observed via X-ray diffraction. We\nidentified the phonons using the shell-model calculation. Furthermore, we\nstudied temperature-dependent behaviors of the phonon modes of three\nrepresentative samples: PV, and two BMs (BM$_{\\mathrm{oop}}$ and\nBM$_{\\mathrm{ip}}$) with different orientations of the oxygen vacancy channel.\nIn the BM$_{\\mathrm{oop}}$ sample, we observed a phonon mode, which exhibited\nan unusual red-shift with decreasing temperature; this behavior may have been\ndue to the apical oxygen instability in the FeO$_6$ octahedron. Our results\nprovide important information regarding the ionic conduction mechanism in\nSrFeO$_{3-x}$ material systems.",
        "positive": "Mechanism for the \u03b1 -> \u03b5 phase transition in iron: The mechanism of the {\\alpha}-{\\epsilon} transition in iron is reconsidered.\nA path in the Burgers description of the bcc/hcp transition different from\nthose previously considered is proposed. It relies on the assumption that shear\nand shuffle are decoupled and requires some peculiar magnetic order, different\nfrom that of {\\alpha} and {\\epsilon} phases as found in Density-Functional\nTheory. Finally, we put forward an original mechanism for this transition,\nbased on successive shuffle motion of layers, which is akin to a\nnucleation-propagation process rather than to some uniform motion."
    },
    {
        "anchor": "Magnetic properties of Sn-substituted Ni-Zn ferrite:synthesized from\n  nano-sized powders of NiO, ZnO, Fe2O3 and SnO2: A series of Ni0.6-x/2Zn0.4-x/2SnxFe2O4 (x = 0.0, 0.05, 0.1, 0.15, 0.2 and\n0.3) (NZSFO) ferrite composites have been synthesized from nano powders using\nstandard solid state reaction technique. The spinel cubic structure of the\ninvestigated samples has been observed by the X-ray diffraction (XRD). The\nmagnetic properties such as saturation magnetization (Ms), remanent\nmagnetization (Mr), coercive field (Hc) and Bohr magneton (B) are calculated\nfrom the hysteresis loops. The value of Ms is found to decrease with increasing\nSn content in the samples. This change has been successfully explained by the\nvariation of A-B interaction strength due to Sn substitution in different\nsites. The compositional stability and quality of the prepared ferrite\ncomposites have also been endorsed by the fairly constant initial permeability\n(/) over a wide range of frequency region. The decreasing trend of / with\nincreasing Sn content has been observed. Curie temperature (TC) has found to\nincrease with the increase in Sn content. Wide spread frequency utility zone\nindicates that the NZSFO can be considered as a good candidate for use in\nbroadband pulse transformer and wide band read-write heads for video recording.\nThe abnormal behavior for x = 0.05 has been explained with existing theory.",
        "positive": "Crystallographically oriented magnetic ZnFe2O4 nanoparticles synthesized\n  by Fe implantation into ZnO: In this paper, a correlation between structural and magnetic properties of Fe\nimplanted ZnO is presented. High fluence Fe^+ implantation into ZnO leads to\nthe formation of superparamagnetic alpha-Fe nanoparticles. High vacuum\nannealing at 823 K results in the growth of alpha-Fe particles, but the\nannealing at 1073 K oxidized the majority of the Fe nanoparticles. After a long\nterm annealing at 1073 K, crystallographically oriented ZnFe2O4 nanoparticles\nwere formed inside ZnO with the orientation relationship of\nZnFe2O4(111)[110]//ZnO(0001)[1120]. These ZnFe2O4 nanoparticles show a\nhysteretic behavior upon magnetization reversal at 5 K."
    },
    {
        "anchor": "Key factors of ion induced nanopatterning: We have reported the dependence of projectile mass, chemical reactivity and\neffect of molecular beams on the ion induced nano structure formation, when 8\nkeV He1+, N1+, O1+, Ar1+ atomic ions and 16 keV N21+ and O21+ molecular ions\nare bombarded on the Si(100) surface at an incidence angle of 60^{\\circ}.\nAtomic force microscopy (AFM) measurement shows that the initiation and growth\nof ripple structures are determined not only by the collision cascades but also\nby the chemical reactivity and molecular state of the projectiles. This\nexperimental investigation explores the necessary requirements for ion induced\ncontrolled nanopatterning.",
        "positive": "Role of Ge:As ratio in controlling the light-induced response of\n  a-GexAs35-xSe65 thin films: In this paper, we present interesting results on the quantification of\nphotodarkening (PD), photobleaching (PB) and transient PD (TPD) in a-\nGexAs35-xSe65 thin films as a function of network rigidity. Composition\ndependent light-induced responses of these samples indicate that there exist\ntwo parallel competing mechanisms of instantaneous PD arising from the As part\nof the network, and PB arising from the Ge part of the network. Raman spectra\nof the as-prepared and illuminated samples provide first direct evidence of the\nlight-induced structural changes: an increase in AsSe3/2 pyramidal and GeSe4/2\ncorner-sharing tetrahedra units together with new Ge-O bond formation and\ndecrease in energetically unstable edge sharing GeSe4/2 tetrahedra.\nImportantly, for a fixed Se concentration, Ge:As ratio plays the critical role\nin controlling the net light-induced response rather than the much believed\nrigidity of the glassy network."
    },
    {
        "anchor": "Exploding Nitromethane in silico, in real time: Nitromethane (NM) is widely applied in chemical technology as a solvent for\nextraction, cleaning and chemical synthesis. NM was considered safe for a long\ntime, until a railroad tanker car exploded in 1958. We investigate detonation\nkinetics and reaction mechanisms in a variety of systems consisting of NM,\nmolecular oxygen and water vapor. State-of-the-art reactive molecular dynamics\nallows us to simulate reactions in time-domain, as they occur in real life.\nHigh polarity of the NM molecule is shown to play an important role, driving\nthe first exothermic step of the reaction. Presence of oxygen is important for\nfaster oxidation, whereas its optimal concentration is in agreement with the\nproposed reaction mechanism. Addition of water (50 mol%) inhibits detonation;\nhowever, water does not prevent detonation entirely. The reported results\nprovide important insights for improving applications of NM and preserving\nsafety of industrial processes.",
        "positive": "Numerical solution of the relativistic single-site scattering problem\n  for the Coulomb and the Mathieu potential: For a reliable fully-relativistic Korringa-Kohn-Rostoker Green function\nmethod, an accurate solution of the underlying single-site scattering problem\nis necessary. We present an extensive discussion on numerical solutions of the\nrelated differential equations by means of standard methods for a direct\nsolution and by means of integral equations. Our implementation is tested and\nexemplarily demonstrated for a spherically symmetric treatment of a Coulomb\npotential and for a Mathieu potential to cover the full-potential\nimplementation. For the Coulomb potential we include an analytic discussion of\nthe asymptotic behaviour of irregular scattering solutions close to the origin\n($r\\ll1$)."
    },
    {
        "anchor": "Thermoelectric Properties of Mg doped Mercury Selenide HgSe: Using the density functional theory (DFT) in combination with Boltzmann\ntransport theory, the influence of Mg concentrations (x) doping on the\nthermoelectric properties of Hg1-xMgxSe ternary alloys was systematically\ninvestigated. The generalized gradient approximations of Perdew-Burke-Ernzerhof\n(GGA-PBE) have been used to illustrate the exchange correlation potential.\nVarious thermoelectric transport parameters, such as the Seebeck coefficient\n(S), the thermal conductivity over relaxation time, the electrical conductivity\nover relaxation time, the power factor (PF) and the figure of merit (ZT) have\nbeen deduced and discussed. The obtained results of thermoelectric properties\nshow that the studied materials can be useful for room temperature\nthermoelectric devices. It is also found that Mg compositions can increase the\nthermal efficiency of the HgSe alloy.",
        "positive": "Local structure of glassy lithium phosphorus oxynitride thin films: a\n  combined experimental and ab initio approach: Lithium phosphorus oxynitride (LiPON) is an amorphous solid-state lithium ion\nconductor displaying exemplary cyclability against lithium metal anodes. There\nis no definitive explanation for this stability due to the limited\nunderstanding of the structure of LiPON. We provide a structural model of\nRF-sputtered LiPON via experimental and computational spectroscopic methods.\nInformation about the short-range structure results from 1D and 2D solid-state\nnuclear magnetic resonance experiments investigating chemical shift anisotropy\nand dipolar interactions. These results are compared with first principles\nchemical shielding calculations of Li-P-O/N crystals and ab initio molecular\ndynamics-generated amorphous LiPON models to unequivocally identify the glassy\nstructure as primarily isolated phosphate monomers with N incorporated in both\napical and as bridging sites in phosphate dimers. Structural results suggest\nLiPON's stability is a result of its glassy character. Free-standing LiPON\nfilms are produced that exhibit a high degree of flexibility highlighting the\nunique mechanical properties of glassy materials."
    },
    {
        "anchor": "Investigation of ITO based liquid sensor for ammonia hydroxide detection: We proposed an Indium Tin Oxide (ITO) sensor for detecting the NH4OH in\nseawater and carried out a series of experiments to investigate the feasibility\nof it as a hazardous and noxious substance (HNS) sensor. The ITO layer revealed\na distinct resistance change ({\\delta}R) which is linearly correlated with the\nNH4OH concentration. Sensing mechanism of the porous ITO layer has been\nexplained in terms of reduction and electrical double layer (EDL) formation.\nAlso, the chemical stability of ITO as a HNS sensor has verified.",
        "positive": "Roles of oxygen vacancies on ferromagnetism in Ni doped In2O3: A hybrid\n  functional study: The roles of oxygen vacancies on the electronic and magnetic properties of Ni\ndoped In$_2$O$_3$ have been studied by first-principles calculations based on\nhybrid functional theory. Our results predict that the Ni-doped In$_2$O$_3$\nsystem displays a ferromagnetic semiconducting character. However, the presence\nof oxygen vacancies results in antiferromagnetic coupling between the\nneighboring Ni pair bridged by an oxygen vacancy. The antiferromagnetic\ncoupling is found to arise from the predominant role of superexchange due to\nthe strong Ni 3d-O 2p hybridization. Consequently, the oxygen vacancies play a\nkey role in the lower saturation magnetization of Ni:In$_2$O$_3$\npolycrystalline sample, as observed in experiments."
    },
    {
        "anchor": "Shear and breathing modes of layered materials: Layered materials (LMs), such as graphite, hexagonal boron nitride, and\ntransition-metal dichalcogenides, are at the centre of an ever increasing\nresearch effort, due to their scientific and technological relevance. Raman and\ninfrared spectroscopies are accurate, non-destructive, approaches to determine\na wide range of properties, including the number of layers and the strength of\nthe interlayer interactions. Here, we present a general approach to predict the\ncomplete spectroscopic fan diagrams, i.e., the relations between frequencies\nand number of layers, $N$, for the optically-active shear and layer-breathing\nmodes of any multilayer comprising $N \\geq 2$ identical layers. In order to\nachieve this, we combine a description of the normal modes in terms of a\none-dimensional mechanical model, with symmetry arguments that describe the\nevolution of the point group as a function of $N$. Group theory is then used to\nidentify which modes are Raman and/or infrared active, and to provide diagrams\nof the optically-active modes for any stack composed of identical layers. We\nimplement the method and algorithms in an open-source tool directly available\non the Materials Cloud portal, to assist any researcher in the prediction and\ninterpretation of such diagrams. Our work will underpin all future efforts on\nRaman and Infrared characterization of known, and yet not investigated, LMs.",
        "positive": "Symmetry Analysis with Spin Crystallographic Groups: Disentangling\n  Spin-Orbit-Free Effects in Emergent Electromagnetism: Recent studies identified spin-order-driven phenomena such as spin-charge\ninterconversion without relying on the relativistic spin-orbit interaction.\nThose physical properties can be prominent in systems containing light magnetic\natoms due to sizable exchange splitting and may pave the way for realizations\nof giant responses correlated with the spin degree of freedom. In this paper,\nwe present a systematic symmetry analysis based on the spin crystallographic\ngroups and identify physical property of a vast number of magnetic materials up\nto 1500 in total. Absence of spin-orbital entanglement leads to the spin\ncrystallographic symmetry having richer property compared to the well-known\nmagnetic space group symmetry. By decoupling the spin and orbital degrees of\nfreedom, our analysis enables us to take a closer look into the relation\nbetween the dimensionality of spin structures and the resultant physical\nproperties and to identify the spin and orbital contributions separately. In\nstark contrast to the established analysis with magnetic space groups, the spin\ncrystallographic group manifests richer symmetry including spin translation\nsymmetry and leads to nontrivial emergent responses. For representative\nexamples, we discuss geometrical nature of the anomalous Hall effect and\nmagnetoelectric effect, and classify the spin Hall effect arising from the\nspontaneous spin-charge coupling. Using the power of computational analysis, we\napply our symmetry analysis to a wide range of magnets, encompassing complex\nmagnets such as those with noncoplanar spin structures as well as collinear and\ncoplanar magnets. We identify emergent multipoles relevant to physical\nresponses and argue that our method provides a systematic tool for exploring\nsizable electromagnetic responses driven by spin ordering."
    },
    {
        "anchor": "On the persistence of polar domains in ultrathin ferroelectric\n  capacitors: The instability of ferroelectric ordering in ultra-thin films is one of the\nmost important fundamental issues pertaining realization of a number of\nelectronic devices with enhanced functionality, such as ferroelectric and\nmultiferroic tunnel junctions or ferroelectric field effect transistors. In\nthis paper, we investigate the polarization state of archetypal ultrathin\n(several nanometres) ferroelectric heterostructures: epitaxial\nsingle-crystalline BaTiO$_3$ films sandwiched between the most habitual\nperovskite electrodes, SrRuO$_3$, on top of the most used perovskite substrate,\nSrTiO$_3$. We use a combination of piezoresponse force microscopy, dielectric\nmeasurements and structural characterization to provide conclusive evidence for\nthe ferroelectric nature of the relaxed polarization state in ultrathin\nBaTiO$_3$ capacitors. We show that even the high screening efficiency of\nSrRuO$_3$ electrodes is still insufficient to stabilize polarization in\nSrRuO$_3$/BaTiO$_3$/SrRuO$_3$ heterostructures at room temperature. We identify\nthe key role of domain wall motion in determining the macroscopic electrical\nproperties of ultrathin capacitors and discuss their dielectric response in the\nlight of the recent interest in negative capacitance behaviour.",
        "positive": "Chemistry at graphene edges in the electron microscope: Transmission electron microscopy (TEM) and scanning TEM (STEM) are\nindispensable tools for materials characterization. However, during a typical\n(S)TEM experiment, the sample is subject to a number of effects that can change\nits atomic structure. Of these, perhaps the least discussed are chemical\nmodifications due to the non-ideal vacuum around the sample. With single-layer\ngraphene, we show that even at relatively low pressures typical for many\ninstruments, these processes can have a significant impact on the sample\nstructure. For example, pore growth becomes up to two orders of magnitude\nfaster at a pressure of ca. 10^{-6} mbar as compared to ultra-high vacuum (UHV;\n10^{-10} mbar). Even more remarkably,the presence of oxygen at the sample also\nchanges the observed atomic structure: When imaged in UHV, nearly 90% of the\nidentifiable graphene edge configurations have the armchair structure, whereas\narmchair and zigzag structures are nearly equally likely to occur when the\noxygen partial pressure in the column is higher. Our results both bring\nattention to the role of the often neglected vacuum composition of the\nmicroscope column, and show that control over it can allow atomic-scale\ntailoring of the specimen structure."
    },
    {
        "anchor": "Linear and nonlinear optical responses in the chiral multifold semimetal\n  RhSi: Chiral topological semimetals are materials that break both inversion and\nmirror symmetries. They host interesting phenomena such as the quantized\ncircular photogalvanic effect (CPGE) and the chiral magnetic effect. In this\nwork, we report a comprehensive theoretical and experimental analysis of the\nlinear and non-linear optical responses of the chiral topological semimetal\nRhSi, which is known to host multifold fermions. We show that the\ncharacteristic features of the optical conductivity, which display two distinct\nquasi-linear regimes above and below 0.4 eV, can be linked to excitations of\ndifferent kinds of multifold fermions. The characteristic features of the CPGE,\nwhich displays a sign change at 0.4 eV and a large non-quantized response peak\nof around 160 $\\mu \\textrm{A V}^{-2}$ at 0.7 eV, are explained by assuming that\nthe chemical potential crosses a flat hole band at the Brillouin zone center.\nOur theory predicts that, in order to observe a quantized CPGE in RhSi, it is\nnecessary to increase the chemical potential as well as the quasiparticle\nlifetime. More broadly our methodology, especially the development of the\nbroadband terahertz emission spectroscopy, could be widely applied to study\nphoto-galvanic effects in noncentrosymmetric materials and in topological\ninsulators in a contact-less way and accelerate the technological development\nof efficient infrared detectors based on topological semimetals.",
        "positive": "Second-Order Spectral Lineshapes from Charged Interfaces: Second-order nonlinear spectroscopy has proven to be a powerful tool in\nelucidating key chemical and structural characteristics at a variety of\ninterfaces. However, the presence of interfacial potentials may lead to\ncomplications regarding the interpretation of second harmonic and vibrational\nsum frequency generation responses from charged interfaces due to mixing of\nabsorptive and dispersive contributions. Here, we examine by means of\nmathematical modeling how this interaction influences second-order spectral\nlineshapes. We discuss our findings in the context of reported nonlinear\noptical spectra obtained from charged water/air and solid/liquid interfaces and\ndemonstrate the importance of accounting for the interfacial\npotential-dependent \\c{hi}(3) term in interpreting lineshapes when seeking\nmolecular information from charged interfaces using second-order spectroscopy."
    },
    {
        "anchor": "Structure maps for hcp metals from first principles calculations: The ability to predict the existence and crystal type of ordered structures\nof materials from their components is a major challenge of current materials\nresearch. Empirical methods use experimental data to construct structure maps\nand make predictions based on clustering of simple physical parameters. Their\nusefulness depends on the availability of reliable data over the entire\nparameter space. Recent development of high throughput methods opens the\npossibility to enhance these empirical structure maps by {\\it ab initio}\ncalculations in regions of the parameter space where the experimental evidence\nis lacking or not well characterized. In this paper we construct enhanced maps\nfor the binary alloys of hcp metals, where the experimental data leaves large\nregions of poorly characterized systems believed to be phase-separating. In\nthese enhanced maps, the clusters of non-compound forming systems are much\nsmaller than indicated by the empirical results alone.",
        "positive": "Variations of Interatomic Force Constants in the Topological Phonon\n  Phase Transition of AlGaN: The topological effects of phonons have been extensively studied in various\nmaterials, particularly in the wide-bandgap semiconductor GaN, which has the\npotential to improve heat dissipation in power electronics due to its\nintrinsic, topologically-protected, non-dissipative phonon surface states.\nNevertheless, the phase transition of the Weyl phonons in nitrides and their\ncomposite alloys has yet to be elucidated. To unveil the microscale origin,\ntopological phonon properties in AlGaN alloys are investigated using the\nvirtual crystal approximation (VCA) and special quasi-random structure (SQS)\napproaches in this work. It is found that phase transitions in Weyl phonons are\nevidently present in AlGaN alloys and nitride single crystals. Under strain\nstates, both GaN and AlN show a more prominent phase transition of Weyl phonons\nwhen subjected to biaxial compressive and uniaxial tensile strains. And it has\nbeen observed that the zz components in the self-term and the transverse 1NN\nforce constants (FCs) are the most influential during the phase transition. The\nnonlinear Weyl phonon transition in AlGaN alloys, as modeled by the VCA, is\nreflected in the normalized self-term and first-nearest-neighbor (1NN) FCs,\nwhich vary in a nonlinear fashion with an increasing magnitude. This nonlinear\nphenomenon is also confirmed in the SQS modeling, where the unfolded phonon\ndispersions are consistent with those in the VCA modeling. With increased\nbranches, hundreds of Weyl phonons are present accompanied by significant\ndisorders in normalized FCs, which mainly occur for N atoms in self-terms and\nfor all components in normalized 1NN FCs."
    },
    {
        "anchor": "LaPtSb: a half-Heusler compound with high thermoelectric performance: The electronic and transport properties of the half-Heusler compound LaPtSb\nare investigated by performing first-principles calculations combined with\nsemi-classical Boltzmann theory and deformation potential theory. Compared with\nmany typical half-Heusler compounds, the LaPtSb exhibits obviously larger power\nfactor at room temperature, especially for the n-type system. Together with the\nvery low lattice thermal conductivity, the thermoelectric figure of merit (ZT)\nof LaPtSb can be optimized to a record high value of 2.2 by fine tuning the\ncarrier concentration.",
        "positive": "Efficient basis expansion for describing linear and nonlinear electron\n  dynamics in crystalline solids: We propose an efficient basis expansion for electron orbitals to describe\nreal-time electron dynamics in crystalline solids. Although a conventional grid\nrepresentation in the three-dimensional Cartesian coordinates works robustly,\nit requires a large amount of computational resources. To reduce computational\ncosts, we consider an expansion using basis functions with a truncation. A\nsimple choice employing eigenstates of the ground state Hamiltonian with a\ntruncation turned out to be useless. We have found that adding occupied\neigenstates of nearby $k$-points to the truncated basis functions composed of\neigenstates of the original $k$-point is crucially important. We demonstrate\nthe usefulness of the method for linear and nonlinear electron dynamics\ncalculations in crystalline SiO$_2$."
    },
    {
        "anchor": "Characterization of in-gap states in epitaxial CoFe2O4(111) layers grown\n  on Al2O3(111)/Si(111) by resonant inelastic x-ray scattering: We have studied in-gap states in epitaxial CoFe2O4(111), which potentially\nacts as a perfect spin filter, grown on a Al2O3(111)/Si(111) structure by using\nellipsometry, Fe L2,3-edge x-ray absorption spectroscopy (XAS), and Fe\nL2,3-edge resonant inelastic x-ray scattering (RIXS), and revealed the relation\nbetween the in-gap states and chemical defects due to the Fe2+ cations at the\noctahedral sites (Fe2+ (Oh) cations). The ellipsometry measurements showed the\nindirect band gap of 1.24 eV for the CoFe2O4 layer and the Fe L2,3-edge XAS\nconfirmed the characteristic photon energy for the preferential excitation of\nthe Fe2+ (Oh) cations. In the Fe L3-edge RIXS spectra, a band-gap excitation\nand an excitation whose energy is smaller than the band-gap energy (Eg = 1.24\neV) of CoF2O4, which we refer to as \"below-band-gap excitation (BBGE)\"\nhereafter, were observed. The intensity of the BBGE was strengthened at the\npreferential excitation energy of the Fe2+ (Oh) cations. In addition, the\nintensity of the BBGE was significantly increased when the thickness of the\nCoFe2O4 layer was decreased from 11 to 1.4 nm, which coincides with the\nincrease in the site occupancy of the Fe2+ (Oh) cations with decreasing the\nthickness. These results indicate that the BBGE comes from the in-gap states of\nthe Fe2+ (Oh) cations whose density increases near the heterointerface on the\nbottom Al2O3 layer. We have demonstrated that RIXS measurements and analyses in\ncombination with ellipsometry and XAS are effective to provide an insight into\nin-gap states in thin-film oxide heterostructures.",
        "positive": "Extended Huckel theory for bandstructure, chemistry, and transport. II.\n  Silicon: In this second paper, we develop transferable semi-empirical parameters for\nthe technologically important material, silicon, using Extended Huckel Theory\n(EHT) to calculate its electronic structure. The EHT-parameters areoptimized to\nexperimental target values of the band dispersion of bulk-silicon. We obtain a\nvery good quantitative match to the bandstructure characteristics such as\nbandedges and effective masses, which are competitive with the values obtained\nwithin an $sp^3 d^5 s^*$ orthogonal-tight binding model for silicon. The\ntransferability of the parameters is investigated applying them to different\nphysical and chemical environments by calculating the bandstructure of two\nreconstructed surfaces with different orientations: Si(100) (2x1) and Si(111)\n(2x1). The reproduced $\\pi$- and $\\pi^*$-surface bands agree in part\nquantitatively with DFT-GW calculations and PES/IPES experiments demonstrating\ntheir robustness to environmental changes. We further apply the silicon\nparameters to describe the 1D band dispersion of a unrelaxed rectangular\nsilicon nanowire (SiNW) and demonstrate the EHT-approach of surface passivation\nusing hydrogen. Our EHT-parameters thus provide a quantitative model of\nbulk-silicon and silicon-based materials such as contacts and surfaces, which\nare essential ingredients towards a quantitative quantum transport simulation\nthrough silicon-based heterostructures."
    },
    {
        "anchor": "Bias current dependence of the spin lifetime in insulating\n  Al$_{0.3}$Ga$_{0.7}$As: The spin lifetime and Hanle signal amplitude dependence on bias current has\nbeen investigated in insulating Al$_{0.3}$Ga$_{0.7}$As:Si using a\nthree-terminal Hanle effect geometry. The amplitudes of the Hanle signals are\nmuch larger for forward bias than for reverse bias, although the spin lifetimes\nfound are statistically equivalent. The spin resistance-area product shows a\nstrong increase with bias current for reverse bias and small forward bias until\n150 $\\mu$A, beyond which a weak dependence is observed. The spin lifetimes\ndiminish substantially with increasing bias current. The dependence of the spin\naccumulation and lifetime diminish only moderately with temperature from 5 K to\n30 K.",
        "positive": "Self Assembly of and Plasmon Enhanced Ultrafast Magnetization in Ag Co\n  Hybrid Nanoparticles: Ultrafast demagnetization in magnetic nanoparticles using pulsed laser has\nattracted considerable attention because of its potential applications in\nspintronics, such as data storage. In such applications, it is necessary to\ncontrol magnetization using low energy laser pulses, however, this poses the\nproblem of increasing the amount of energy from the excitation laser pulses to\nthe spin subsystem. We take advantage of the phenomenon known as localized\nsurface plasmon resonance (LSPR) to enhance the energy transfer from laser\npulses to the spin subsystem. To induce LSPR, hybrid nanoparticles consisting\nof noble metal nanoparticles with LSPR absorption and magnetic metal\nnanoparticles are prepared using a novel method. Specifically, AgCo hybrid\nnanoparticles are prepared by a self assembly method using pulsed laser\ndeposition. We performed measurements of the static Faraday and time-resolved\nFaraday effects using a pump probe technique on the AgCo hybrid nanoparticles\nwith various AgCo ratios. The data suggest that the LSPR absorption and\ndemagnetization amplitude increase with the increasing AgCo ratio. The results\nindicate that the amount of energy transferred from the laser pulses to the\nspin system of magnetic nanoparticles can increase via LSPR absorption."
    },
    {
        "anchor": "Comparative study of hydrogen embrittlement resistance between\n  additively and conventionally manufactured austenitic stainless steels: Hydrogen embrittlement in 304L (18wt.% Cr, 8-10wt.% Ni) austenitic stainless\nsteel (ASS) fabricated by laser powder-bed-fusion (LPBF) was investigated by\ntensile testing after electrochemical hydrogen pre-charging and compared to\nconventionally available 304L ASSs with two different processing histories, (i)\ncasting plus annealing (CA) and (ii) CA plus thermomechanical treatment (TMT).\nIt was revealed that hydrogen-charging led to a significant reduction in\nductility for the CA sample, but only a small effect of hydrogen was observed\nfor the LPBF and CA-TMT samples. Hydrogen-assisted cracking behavior was found\nto be strongly linked to strain-induced martensitic transformation. In\naddition, the amount of alpha' martensite was much higher in the CA sample than\nin other samples, suggesting that severe hydrogen embrittlement can be\ncorrelated with the low mechanical stability of austenite. Detailed\nmicrostructural characterization showed that low austenite stability of the CA\nsample was mainly attributed to the retained content of delta ferrite and the\nchemical inhomogeneity inside the gamma matrix (gamma close to delta has ~2\nwt.% higher Cr but ~2 wt.% lower Ni), but TMT enhanced the chemical homogeneity\nand thus austenite stability. By contrast, the LPBF process led directly, i.e.\nwithout any thermomechanical treatment, to a fully austenitic structure with\nhomogeneous elemental distribution in the ASS. These results confirmed that the\npresence of delta and the chemical inhomogeneity inside gamma matrix, which\npromoted the deformation-induced martensitic transformation and the associated\nH enrichment at the gamma-alpha' interface, was the primary reason for the\nsevere H-assisted failure.",
        "positive": "Effect of pressure on the order-disorder phase transitions of\n  $B$-cations in $AB'_{1/2}B''_{1/2}$O$_3$ perovskites: Perovskite-like oxides $AB'_{1/2}B''_{1/2}$O$_3$ may experience different\nordering degrees of $B$-cations, that can be varied by suitable synthesis\nconditions or post-synthesis treatment. In this work the earlier proposed\nstatistical model of order-disorder phase transitions of $B$-cations is\nextended to account for the effect of pressure. Depending on composition,\npressure is found to either increase or decrease the order-disorder phase\ntransition temperature. The change of transition temperature due to pressure in\nmany cases reaches several hundreds of kelvin at pressures accessible in\nlaboratory, which may significantly change the atomic ordering degree. The work\nis intended to help determining how pressure influences the degree of atomic\nordering and stimulate research of the effect of pressure on atomic\norder-disorder phase transitions in perovskites."
    },
    {
        "anchor": "Reduction of magnetostatic interactions in self-organized arrays of\n  nickel nanowires using atomic layer deposition: Ordered arrays of magnetic nanowires are commonly synthesized by\nelectrodeposition in nanoporous alumina templates. Due to their dense packing,\nstrong magnetostatic interactions prevent the manipulation of wires\nindividually. Using atomic layer deposition we reduce the diameter of the pores\nprior to electrodeposition. This reduces magnetostatic interactions, yielding\nfully remanent hysteresis loops. This is a first step towards the use of such\narrays for magnetic racetrack memories.",
        "positive": "Preisach images of a simple mechanical system: This work is an an early stage of a larger project aiming at answering the\nquestion whether or not the Preisach map is really fingerprinting magnetic\nmaterials. More precisely, we are interested whether Preisach model of magnetic\nhysteresis indeed contains any physics or is just a convenient modeling tool.\nTo this extent we study a very simple mechanical system, thus fully tractable,\nsubjected to the external force. Despite of its simplicity, our model captures\nall the fundamental features of real magnetic materials, namely their\nhysteretic behavior, coercivity, remanent magnetization and saturation at high\nfields. Both the overall shape of major hysteresis loop as well as First Order\nReversal Curves (FORC's) are reproduced quite correctly; they are very similar\nto those observed in magnetic materials. The model essentially consists of a\nsingle, spring loaded, rigid and rotative bar with non-zero friction torque.\nThe length of a projection of this bar onto the direction of an external force\nis identified with magnetization. The friction torque and the spring constant\nare the only freely adjustable parameters of our model. Here we investigate,\nand present, their influence on the inferred Preisach maps."
    },
    {
        "anchor": "The Diamond (111) Surface Reconstruction and Epitaxial Graphene\n  Interface: The evolution of the diamond (111) surface as it undergoes reconstruction and\nsubsequent graphene formation is investigated with angle-resolved photoemission\nspectroscopy, low energy electron diffraction, and complementary density\nfunctional theory calculations. The process is examined starting at the\nC(111)-(2x1) surface reconstruction that occurs following detachment of the\nsurface adatoms at 920 {\\deg}C, and continues through to the liberation of the\nreconstructed surface atoms into a free-standing monolayer of epitaxial\ngraphene at temperatures above 1000 {\\deg}C. Our results show that the\nC(111)-(2x1) surface is metallic as it has electronic states that intersect the\nFermi-level. This is in strong agreement with a symmetrically {\\pi}-bonded\nchain model and should contribute to resolving the controversies that exist in\nthe literature surrounding the electronic nature of this surface. The graphene\nformed at higher temperatures exists above a newly formed C(111)-(2\\times1)\nsurface and appears to have little substrate interaction as the Dirac-point is\nobserved at the Fermi-level. Finally, we demonstrate that it is possible to\nhydrogen terminate the underlying diamond surface by means of plasma processing\nwithout removing the graphene layer, forming a graphene-semiconductor\ninterface. This could have particular relevance for doping the graphene formed\non the diamond (111)surface via tuneable substrate interactions as a result of\nchanging the terminating species at the diamond-graphene interface by plasma\nprocessing.",
        "positive": "On the Formation of Copper Linear Atomic Suspended Chains: We report high resolution transmission electron microscopy and classical\nmolecular dynamics simulation results of mechanically stretching copper\nnanowires conducting to linear atomic suspended chains (LACs) formation. In\ncontrast with some previous experimental and theoretical work in literature\nthat stated that the formation of LACs for copper should not exist our results\nshowed the existence of LAC for the [111], [110], and [100] crystallographic\ndirections, being thus the sequence of most probable occurence."
    },
    {
        "anchor": "Perpendicular magnetic anisotropy in ultra-thin Cu$_2$Sb-type\n  (Mn-Cr)AlGe films onto thermally oxidized silicon substrates: Perpendicularly magnetized films showing small saturation magnetization,\n$M_\\mathrm{s}$, are essential for spin-transfer-torque writing type\nmagnetoresistive random access memories, STT-MRAMs. An intermetallic compound,\n{(Mn-Cr)AlGe} of the Cu$_2$Sb-type crystal structure was investigated, in this\nstudy, as a material showing the low $M_\\mathrm{s}$ ($\\sim 300$ kA/m) and\nhigh-perpendicular magnetic anisotropy, $K_\\mathrm{u}$. The layer thickness\ndependence of $K_\\mathrm{u}$ and effects of Mg-insertion layers at top and\nbottom (Mn-Cr)AlGe$|$MgO interfaces were studied in film samples fabricated\nonto thermally oxidized silicon substrates to realize high-$K_\\mathrm{u}$ in\nthe thickness range of a few nanometer. Optimum Mg-insertion thicknesses were\n1.4 and 3.0 nm for the bottom and the top interfaces, respectively, which were\nrelatively thick compared to results in similar insertion effect investigations\non magnetic tunnel junctions reported in previous studies. The cross-sectional\ntransmission electron microscope images revealed that the Mg-insertion layers\nacted as barriers to interdiffusion of Al-atoms as well as oxidization from the\nMgO layers. The values of $K_\\mathrm{u}$ were about $7 \\times 10^5$ and $2\n\\times 10^5$ J/m$^3$ at room temperature for 5 and 3 nm-thick (Mn-Cr)AlGe\nfilms, respectively, with the optimum Mg-insertion thicknesses. The\n$K_\\mathrm{u}$ at a few nanometer thicknesses is comparable or higher than\nthose reported in perpendicularly magnetized CoFeB films which are\nconventionally used in MRAMs, while the $M_\\mathrm{s}$ value is one third or\nless smaller than those of the CoFeB films. The developed (Mn-Cr)AlGe films are\npromising from the viewpoint of not only the magnetic properties, but also the\ncompatibility to the silicon process in the film fabrication.",
        "positive": "Piezoresponse of ferroelectric films in ferroionic states: time and\n  voltage dynamics: The interplay between electrochemical surface charges and bulk\nferroelectricity in thin films gives rise to a continuum of coupled ferro-ionic\nstates. These states are exquisitely sensitive to chemical and electric\nconditions at the surfaces, applied voltage, and oxygen pressure. Using the\nanalytical approach combining the Ginzburg-Landau-Devonshire description of the\nferroelectricity with Langmuir adsorption isotherm for the ions at the film\nsurface, we have studied the temperature-, time- and field- dependent\npolarization changes and electromechanical response of the ferro-ionic states.\nThe responses are found to be inseparable in thermodynamic equilibrium and at\nlow frequencies of applied voltage. The states become separable in high\nfrequency dynamic mode due to the several orders of magnitude difference in the\nrelaxation times of ferroelectric polarization and surface ions charge density.\nThese studies provide an insight into dynamic behavior of nanoscale\nferroelectrics with open surface exposed to different kinds of\nelectrochemically active gaseous surrounding."
    },
    {
        "anchor": "On the Debye temperature in sigma-phase Fe-V alloys: A series of sigma-phase Fe_{100-x}V_x samples with 34.4 < x < 59.0 were\ninvestigated by neutron and X-ray diffraction and Mossbauer spectroscopy (MS)\ntechniques. The first two methods were used for verification of the\ntransformation from alpha to sigma phase and they also permitted to determine\nlattice parameters of the unit cell. With MS the Debye temperature, T_D, was\nevaluated from the temperature dependence of the centre shift, <CS>, assuming\nits entire temperature dependence originates from the second-order Doppler\nshift. To our best knowledge, it is the first ever-reported study on T_D in\nsigma-FeV alloys. Both attice parameters i.e. a and c were revealed to linearly\nincrease with x. T_D shows, however, a non-monotonic behaviour as a function of\ncomposition with its extreme values between 425K for x=40 and 600K for x=59. A\nlocal maximum of 525K was found to exist at x=43.",
        "positive": "Transport Waves as Crystal Excitations: We introduce the concept of transport waves by showing that the linearized\nBoltzmann transport equation admits excitations in the form of waves that have\nwell defined dispersion relations and decay times. Crucially, these waves do\nnot represent single-particle excitations, but are collective excitations of\nthe equilibrium distribution functions. We study in detail the case of thermal\ntransport, where relaxons are found in the long-wavelength limit, and second\nsound is reinterpreted as the excitation of one or several temperature waves at\nfinite frequencies. Graphene is studied numerically, finding decay times of the\norder of microseconds. The derivation, obtained by a spectral representation of\nthe Boltzmann equation, holds in principle for any crystal or semiclassical\ntransport theory and is particularly relevant when transport takes place in the\nhydrodynamic regime."
    },
    {
        "anchor": "Benchmarking of spin-orbit torque switching efficiency in Pt alloys: We systematically survey on Pt$_{x}$Cu$_{1-x}$/Co/MgO magnetic\nheterostructure with perpendicular magnetic anisotropy and report a significant\nimprovement on spin-orbit torque switching efficiency in Pt-Cu alloy system.\nThe largest damping-like spin-orbit torque efficiency determined by hysteresis\nloop shift measurement is about 0.44 for Pt$_{0.57}$Cu$_{0.43}$, which is\noriginated from the higher resistivity tuned by alloying. Moreover, from the\nresults of current-induced switching measurements, a lower critical switching\ncurrent density is achieved by proper alloying due to the simultaneous\nenhancement of spin-orbit torque efficiency and reduction of coercivity of the\nCo layer. Finally, the ability to lower power consumption and preserve good\nthermal stability using Pt$_{x}$Cu$_{1-x}$ alloy is demonstrated, which\nsuggests that Pt$_{x}$Cu$_{1-x}$ is an attractive candidate for future SOT-MRAM\napplications.",
        "positive": "High-throughput computational characterization of two-dimensional\n  compositionally complex transition-metal chalcogenide alloys: Two-dimensional (2D) binary transition-metal chalcogenides (TMCs) like\nmolybdenum disulfide exhibits excellent properties as materials for light\nadsorption devices. Alloying binary TMCs can form 2D compositionally complex\nTMC alloys (CCTMCAs) that possess remarkable properties from the constituent\nTMCs. We adopt a high-throughput workflow performing density functional theory\n(DFT) calculations based on the virtual crystal approximation (VCA) model\n(VCA-DFT). We test the workflow by predicting properties including in-plane\nlattice constants, band gaps, effective masses, spin-orbit coupling (SOC), and\nband alignments of the Mo-W-S-Se, Mo-W-S-Te, and Mo-W-Se-Te 2D CCTMCAs. We\nvalidate the VCA-DFT results by computing the same properties using unit cells\nand supercells of selected compositions. The VCA-DFT results of the\nabovementioned five properties are comparable to that of DFT calculations, with\nsome inaccuracies in several properties of MoSTe and WSTe. Moreover, 2D CCTMCAs\ncan form type II heterostructures as used in photovoltaics. Finally, we use\nMo0.5W0.5SSe, Mo0.5W0.5STe, and Mo0.5W0.5SeTe 2D CCTMCAs to demonstrate the\nroom-temperature entropy-stabilized alloys. They also exhibit high electrical\nconductivities at 300K, promising for light adsorption devices. Our work shows\nthat the high-throughput workflow using VCA-DFT calculations provides a\ntradeoff between efficiency and accuracy, opening up opportunities in the\ncomputational design of other 2D CCTMCAs for various applications."
    },
    {
        "anchor": "Wave Propagation in Undulated Structural Lattices: This work investigates wave propagation in undulated square structural\nlattices. The undulated pattern is obtained by imposing an initial curvature to\nthe lattice's elements. The study considers both periodic undulated structures,\nin which the undulation is uniform throughout the structure as well as graded\nundulated patterns, in which the undulation is modulated within the lattice.\nUndulation is specifically considered in relation to its ability to induce\nanisotropy in the equivalent mechanical properties and to break the symmetry of\nthe straight square lattice. Results show that wave motion is inhibited within\nspecified frequency ranges owing to the generation of band gaps, and in\nspecific directions as a result of the undulation-induced anisotropy.",
        "positive": "Low-Temperature Dependences of the Polarization of Terahertz Emission\n  from $n$-Germanium in Heating Electric Fields: As was noted in [3], in order to verify the assumption that the behavior of\nthe polarization dependences of the terahertz emission by hot electrons from\n$n$-Ge is determined by the type of carrier scattering, it is necessary to\nperform temperature measurements of this dependence in the range between the\ntemperatures, where the scattering is determined by impurities and by acoustic\nlattice vibrations, respectively. The given work presents the results of such\ninvestigations."
    },
    {
        "anchor": "Three-Dimensional Electronic Structure of type-II Weyl Semimetal WTe$_2$: By combining bulk sensitive soft-X-ray angular-resolved photoemission\nspectroscopy and accurate first-principles calculations we explored the bulk\nelectronic properties of WTe$_2$, a candidate type-II Weyl semimetal featuring\na large non-saturating magnetoresistance. Despite the layered geometry\nsuggesting a two-dimensional electronic structure, we find a three-dimensional\nelectronic dispersion. We report an evident band dispersion in the reciprocal\ndirection perpendicular to the layers, implying that electrons can also travel\ncoherently when crossing from one layer to the other. The measured Fermi\nsurface is characterized by two well-separated electron and hole pockets at\neither side of the $\\Gamma$ point, differently from previous more surface\nsensitive ARPES experiments that additionally found a significant quasiparticle\nweight at the zone center. Moreover, we observe a significant sensitivity of\nthe bulk electronic structure of WTe$_2$ around the Fermi level to electronic\ncorrelations and renormalizations due to self-energy effects, previously\nneglected in first-principles descriptions.",
        "positive": "The influence of metallic overlayers on ferromagnetism in LaMnO$_3$: LaMnO$_3$ (LMO) thin films epitaxially grown on SrTiO$_3$ (STO) usually\nexhibit ferromagnetism above a critical layer thickness. We report the use of\nscanning SQUID microscopy (SSM) to study the suppression of the ferromagnetism\nin STO/LMO/metal structures. By partially covering the LMO surface with a\nmetallic layer, both covered and uncovered LMO regions can be studied\nsimultaneously. While Au does not significantly influence the ferromagnetic\norder of the underlying LMO film, a thin Ti layer induces a strong suppression\nof the ferromagnetism, over tens of nanometers, and a large change in the\nout-of-plane lattice parameter. We relate the suppression of the ferromagnetism\nto the scavenging of oxygen and diffusion of Ti approximately 5 nanometers deep\ninto the film, which takes place at timescales of days. Furthermore, we\ndemonstrate that by patterning Ti/Au overlayers, we can define ferromagnetic\nstructures down to sub-micrometer scales."
    },
    {
        "anchor": "Electronic and Optical Properties of \u03b3- and \u03b8- Alumina by\n  First Principle Calculations: The electronic and optical parameters of {\\gamma}-Al2O3 and {\\theta}-Al2O3\nhave been studied by using the first principle within the framework of density\nfunction theory (DFT). The computational approach is based on full-potential\nlinearized augmented plane wave method (FP-LAPW) within the generalized\ngradient approximation (GGA), local density approximation (LDA), and modified\nBecke-Johnson potential (mBJ). The results show that these compounds have a\ndirect gap ({\\Gamma}-{\\Gamma}) of about 5.375 eV and 4.716 eV for\n{\\gamma}-Al2O3 and {\\theta}-Al2O3, respectively. Several optical parameters of\nthese materials are also investigated. The values of the real part of\ndielectric constant are found to be 3.259 and 3.694 for {\\gamma}-Al2O3 and\n{\\theta}-Al2O3, respectively, which are close to the experimental one (3.416).\nThe refractive index is 1.806 and 1.922 for {\\gamma}-Al2O3 and {\\theta}-Al2O3\nrespectively, and shows a good agreement with the experimental result which is\n1.86. GGA findings are consistent with the experimental results and are better\nthan the other approximations. There are no salient differences between GGA and\nLDA results. The results advocate using this material as a transparent\nconducting layer in solar cell structure, which can be operated in a wide\nenergy range.",
        "positive": "Persistent X-Ray Photoconductivity and Percolation of Metallic Clusters\n  in Charge-Ordered Manganites: Charge-ordered manganites of composition $\\rm\nPr_{1-x}(Ca_{1-y}Sr_{y})_{x}MnO_3$ exhibit persistent photoconductivity upon\nexposure to x-rays. This is not always accompanied by a significant increase in\nthe {\\it number} of conduction electrons as predicted by conventional models of\npersistent photoconductivity. An analysis of the x-ray diffraction patterns and\ncurrent-voltage characteristics shows that x-ray illumination results in a\nmicroscopically phase separated state in which charge-ordered insulating\nregions provide barriers against charge transport between metallic clusters.\nThe dominant effect of x-ray illumination is to enhance the electron {\\it\nmobility} by lowering or removing these barriers. A mechanism based on magnetic\ndegrees of freedom is proposed."
    },
    {
        "anchor": "Spectroscopic evidence for a spin and valley polarized metallic state in\n  a non-magic-angle twisted bilayer graphene: In the magic-angle twisted bilayer graphene (MA-TBG), strong\nelectron-electron (e-e) correlations caused by the band-flattening lead to many\nexotic quantum phases such as superconductivity, correlated insulator,\nferromagnetism, and quantum anomalous Hall effects, when its low-energy van\nHove singularities (VHSs) are partially filled. Here our high-resolution\nscanning tunneling microscope and spectroscopy measurements demonstrate that\nthe e-e correlation in a non-magic-angle TBG with a twist angle {\\theta} = 1.49\nstill plays an important role in determining its electronic properties. Our\nmost interesting observation on that sample is that when one of its VHS is\npartially filled, the one associated peak in the spectrum splits into four\npeaks. Our analysis based on the continuum model suggests that such a\none-to-four split of the VHS originates from the formation of an\ninteraction-driven spin-valley-polarized metallic state near the VHS, lifting\nboth the spin and valley degeneracies. Our results for this non-magic-angle TBG\nreveal a new symmetry-breaking phase, which has not been identified in the\nMA-TBG or in other systems.",
        "positive": "Mobile Small Polarons Explain Conductivity in Lithium Titanium Oxide\n  Battery Electrodes: Lithium titanium oxide Li$_4$Ti$_5$O$_{12}$ (LTO) is an intriguing anode\nmaterial promising particularly long lived batteries, due to its remarkable\nphase stability during (dis)charging of the cell. However, its usage is limited\nby its low intrinsic electronic conductivity. Introducing oxygen vacancies can\nbe one method to overcome this drawback, possibly by altering the charge\ncarrier transport mechanism. We use Hubbard corrected density-functional theory\n(DFT+U) to show that polaronic states in combination with a possible hopping\nmechanism can play a crucial role in the experimentally observed increase of\nelectronic conductivity. To gauge polaronic charge mobility, we compute\nrelative stabilities of different localization patterns and estimate polaron\nhopping barrier heights. With this we finally show how defect engineering can\nindeed raise the electronic conductivity of LTO up to the level of its ionic\nconductivity, thereby explaining first experimental results for reduced LTO."
    },
    {
        "anchor": "Toward a Comprehensive Model of Snow Crystal Growth: 6. Ice Attachment\n  Kinetics near -5 C: I examine a variety of snow crystal growth measurements taken at a\ntemperature of -5 C, as a function of supersaturation, background gas pressure,\nand crystal morphology. Both plate-like and columnar prismatic forms are\nobserved under different conditions at this temperature, along with a diverse\ncollection of complex dendritic structures. The observations can all be\nreasonably understood using a single comprehensive physical model for the basal\nand prism attachment kinetics, together with particle diffusion of water vapor\nthrough the surrounding medium and other well-understood physical processes. A\ncritical model feature is structure-dependent attachment kinetics (SDAK), for\nwhich the molecular attachment kinetics on a faceted surface depend strongly on\nthe nearby mesoscopic structure of the crystal.",
        "positive": "Geometric and electronic properties of two kinds of CrO2 magnetic\n  monolayers: D3d and D2h phases: Due to the high magnetic coupling strength between the Cr elements, the bulk\nphase CrO2 is one of several ferromagnetic oxides known to have the highest\nCurie temperature. When the dimensionality of the material is reduced from 3D\nto 2D, the 2D CrO2 system material is expected to maintain a high Curie\ntemperature. In this work, we predict two new phases of CrO2 monolayer (D3d and\nD2h) by using first-principles calculations. We have found that the Curie\ntemperature of 2D CrO2 is much lower than that of its bulk phase, but still\nremains as high as 191K, which is comparable to that of Fe2Cr2Ge6. In addition,\n1L D3d-CrO2 is in the ferromagnetic state, while 1L D2h-CrO2 is in the\nantiferromagnetic state. Also, the different geometric structure affects its\nelectrical properties: the 1L D3d-CrO2 is a half-metal while 1L D2h-CrO2 is a\nsemiconductor. Our studies have shown that there is a wealth of electrical and\nmagnetic properties in CrO2."
    },
    {
        "anchor": "Ultra-High Thermoelectric Power Factors in Narrow Gap Materials with\n  Asymmetric Bands: We theoretically unveil the unconventional possibility to achieve extremely\nhigh thermoelectric power factors in lightly doped narrow gap semiconductors\nwith asymmetric conduction/valence bands operated in the bipolar transport\nregime. Specifically, using Boltzmann transport simulations, we show that\nnarrow bandgap materials, rather than suffering from performance degradation\ndue to bipolar conduction, if they possess highly asymmetric conduction and\nvalence bands in terms of either effective masses, density of states, or phonon\nscattering rates, then they can deliver very high power factors. We show that\nthis is reached because, under these conditions, electronic transport becomes\nphonon scattering limited, rather than ionized impurity scattering limited,\nwhich allows large conductivities. We explain why this effect has not been\nobserved so far in the known narrow-gap semiconductors, interpret some recent\nrelated experimental findings, and propose a few examples from the half-Heusler\nmaterials family for which this effect can be observed and power factors even\nup to 50 mW/m$K^2$ can be reached.",
        "positive": "The origin of defects induced in ultra-pure germanium by Electron Beam\n  Deposition: The creation of point defects in the crystal lattices of various\nsemiconductors by subthreshold events has been reported on by a number of\ngroups. These observations have been made in great detail using sensitive\nelectrical techniques but there is still much that needs to be clarified.\nExperiments using Ge and Si were performed that demonstrate that energetic\nparticles, the products of collisions in the electron beam, were responsible\nfor the majority of electron-beam deposition (EBD) induced defects in a\ntwo-step energy transfer process. Lowering the number of collisions of these\nenergetic particles with the semiconductor during metal deposition was\naccomplished using a combination of static shields and superior vacuum\nresulting in devices with defect concentrations lower than $\n10^{11}\\,$cm$^{-3}$, the measurement limit of our deep level transient\nspectroscopy (DLTS) system. High energy electrons and photons that samples are\ntypically exposed to were not influenced by the shields as most of these\nparticles originate at the metal target thus eliminating these particles as\npossible damage causing agents. It remains unclear how packets of energy that\ncan sometimes be as small of 2eV travel up to a $\\mu$m into the material while\nstill retaining enough energy, that is, in the order of 1eV, to cause changes\nin the crystal. The manipulation of this defect causing phenomenon may hold the\nkey to developing defect free material for future applications."
    },
    {
        "anchor": "Antiferromagnetic resonance in ferroborate NdFe$_3$(BO$_3$)$_4: The AFMR spectra of the NdFe$_3$(BO$_3$)$_4$ crystal are measured in a wide\nrange of frequencies and temperatures. It is found that by the type of magnetic\nanisotropy the compound is an \"easy-plane\" antiferromagnet with a weak\nanisotropy in the basal plane. The effective magnetic parameters are\ndetermined: anisotropy fields $H_{a1}$=1.14 kOe and $H_{a2}$=60 kOe and\nmagnetic excitation gaps $\\Delta\\nu_1$=101.9 GHz and $\\Delta \\nu_2$=23.8 GHz.\nIt is shown that commensurate-incommensurate phase transition causes a shift in\nresonance field and a considerable change in absorption line width.\n  At temperatures below 4.2 K nonlinear regimes of AFMR excitation at low\nmicrowave power levels are observed.",
        "positive": "AFLOW$\u03c0$: A minimalist approach to high-throughput ab initio\n  calculations including the generation of tight-binding hamiltonians: Tight-binding models provide a conceptually transparent and computationally\nefficient method to represent the electronic properties of materials. With\nAFLOW$\\pi$ we introduce a framework for high-throughput first principles\ncalculations that automatically generates tight-binding hamiltonians without\nany additional input. Several additional features are included in AFLOW$\\pi$\nwith the intent to simplify the self-consistent calculation of Hubbard U\ncorrections, the calculations of phonon dispersions, elastic properties,\ncomplex dielectric constants, and electronic transport coefficients. As\nexamples we show how to compute the optical properties of layered nitrides in\nthe $AM$N$_2$ family, and the elastic and vibrational properties of binary\nhalides with CsCl and NaCl structure."
    },
    {
        "anchor": "Paramagnetic structure for the soliton of the $30^\\circ$ partial\n  dislocation in silicon: Based on ab initio calculation, we propose a new structure for the\nfundamental excitation of the reconstructed 30$^\\circ$ partial dislocation in\nsilicon. This soliton has a rare structure involving a five-fold coordinated\natom near the dislocation core. The unique electronic structure of this defect\nis consistent with the electron spin resonance signature of the hitherto\nenigmatic thermally stable R center of plastically deformed silicon. This\nidentification suggests the possibility of an experimental determination of the\ndensity of solitons, a key defect in understanding the plastic flow of the\nmaterial.",
        "positive": "Prediction of Topological Crystalline Insulator and Topological Phase\n  Transitions in Two-dimensional PbTe Films: Topological phases, especially topological crystalline insulators (TCIs),\nhave been intensively explored observed experimentally in three-dimensional\n(3D) materials. However, the two-dimensional (2D) films are explored much less\nthan 3D TCI, and even 2D topological insulators. Based on ab initio\ncalculations, here we investigate the electronic and topological properties of\n2D PbTe(001) few-layers. The monolayer and trilayer PbTe are both intrinsic 2D\nTCIs with a large band gap reaching 0.27 eV, indicating a high possibility for\nroom-temperature observation of quantized conductance. The origin of TCI phase\ncan be attributed to the p band inversion,which is determined by the\ncompetitions of orbital hybridization and quantum confinement. We also observe\na semimetal-TCI-normal insulator transition under biaxial strains, whereas a\nuniaxial strains lead to Z2 nontrivial states. Especially, the TCI phase of\nPbTe monolayer remains when epitaxial grow on NaI semiconductor substrate. Our\nfindings on the controllable quantum states with sizable band gaps present an\nideal platform for realizing future topological quantum devices with ultralow\ndissipation."
    },
    {
        "anchor": "Domain formation mechanism of the Si(110)\"16 x 2\" reconstruction: The main factor that determines which of the two domains form upon\nreconstruction of the Si(110)\"16 x 2\" surface has been investigated. LEED and\nSTM images showed that the domain orientation was independent of the heating\ncurrent direction used to induce the Si(110)\"16 x 2\" reconstruction.\nReciprocal-space lattice models of the reconstruction allowed for the correct\nidentification of the domain orientations in the LEED images and confirm that\nthe reconstruction is 2D-chiral. It is proposed that the domain orientation\nupon surface reconstruction is determined by the direction of monoatomic steps\npresent on the Si(110) plane. This is in turn determined by the direction at\nwhich the surface is polished off-axis from the (110) plane.",
        "positive": "Spin-glass states generated in van der Waals magnet Cr$_2$Ge$_2$Te$_6$\n  by alkali-ion intercalation: Tuning magnetic properties in layered van der Waals (vdW) materials has\ncaptured a significant attention due to the efficient control of ground-states\nby heterostructuring and external stimuli. Electron doping by electrostatic\ngating, interfacial charge transfer and intercalation is particularly effective\nin manipulating the exchange and spin-orbit properties, resulting in a control\nof Curie temperature ($T_{\\text{C}}$) and magnetic anisotropy. Here, we\ndiscover an uncharted role of intercalation to generate magnetic frustration.\nAs a model study, we intercalate Na atoms into the vdW gaps of pristine\nCr$_2$Ge$_2$Te$_6$ (CGT) where generated magnetic frustration leads to emerging\nspin-glass states coexisting with a ferromagnetic order. A series of dynamic\nmagnetic susceptibility measurements/analysis confirms the formation of\nmagnetic clusters representing slow dynamics with a distribution of relaxation\ntimes. The intercalation also modifies other macroscopic physical parameters\nincluding the significant enhancement of $T_{\\text{C}}$ from 66K\\, to 240\\,K\nand the switching of magnetic easy-hard axis direction. Our study identifies\nintercalation as a unique route to generate emerging frustrated spin states in\nsimple vdW crystals."
    },
    {
        "anchor": "Anisotropic straining of graphene using micropatterned SiN membranes: We use micro-Raman spectroscopy to study strain profiles in graphene\nmonolayers suspended over SiN membranes micropatterned with holes of\nnon-circular geometry. We show that a uniform differential pressure load\n$\\Delta P$ over elliptical regions of free-standing graphene yields measurable\ndeviations from hydrostatic strain conventionally observed in\nradially-symmetric microbubbles. The top hydrostatic strain $\\bar{\\varepsilon}$\nwe observe is estimated to be $\\approx0.7\\%$ for $\\Delta P = 1\\,{\\rm bar}$ in\ngraphene clamped to elliptical SiN holes with axis $40$ and $20\\,{\\rm \\mu m}$.\nIn the same configuration, we report a $G_\\pm$ splitting of $10\\,{\\rm cm^{-1}}$\nwhich is in good agreement with the calculated anisotropy $\\Delta\\varepsilon\n\\approx 0.6\\%$ for our device geometry. Our results are consistent with the\nmost recent reports on the Gr\\\"uneisen parameters. Perspectives for the\nachievement of arbitrary strain configurations by designing suitable SiN holes\nand boundary clamping conditions are discussed.",
        "positive": "Cluster dynamics modelling of materials: a new hybrid\n  deterministic/stochastic coupling approach: Deterministic simulations of the rate equations governing cluster dynamics in\nmaterials are limited by the number of equations to integrate. Stochastic\nsimulations are limited by the high frequency of certain events. We propose a\ncoupling method combining deterministic and stochastic approaches. It allows\nhandling different time scale phenomena for cluster dynamics. This method,\nbased on a splitting of the dynamics, is generic and we highlight two different\nhybrid deterministic/stochastic methods. These coupling schemes are highly\nparallelizable and specifically designed to treat large size cluster problems.\nThe proof of concept is made on a simple model of vacancy clustering under\nthermal ageing."
    },
    {
        "anchor": "Screw dislocation that converts p-type GaN to n-type: Microscopic study\n  on the Mg condensation and the leakage current in p-n diodes: Recent experiments suggest that Mg condensation at threading dislocations\ninduce current leakage, leading to degradation of GaN-based power devices. To\nstudy this issue, we perform first-principles total-energy electronic-structure\ncalculations for various Mg and dislocation complexes. We find that threading\nscrew dislocations (TSDs) indeed attract Mg impurities, and that the electronic\nlevels in the energy gap induced by the dislocations are elevated towards the\nconduction band as the Mg impurity approaches the dislocation line, indicating\nthat the Mg-TSD complex is a donor. The formation of the Mg-TSD complex is\nunequivocally evidenced by our atom probe tomography in which Mg condensation\nand diffusion through [0001] screw dislocations is observed in p-n diodes.\nThese findings provide a novel picture that the Mg being a p-type impurity in\nGaN diffuses toward the TSD and then locally forms an n-type region. The\nappearance of this region along the TSD results the reverse leakage current.",
        "positive": "Exciton transport in amorphous polymers and the role of morphology and\n  thermalisation: Understanding the transport mechanism of electronic excitations in conjugated\npolymers is key to advancing organic optoelectronic applications, such as solar\ncells, OLEDs and flexible electronics. While crystalline polymers can be\nstudied using solid-state techniques based on lattice periodicity, the\ncharacterisation of amorphous polymers is hindered by an intermediate regime of\ndisorder and the associated lack of symmetries. To overcome these hurdles we\nuse a reduced state quantum master equation approach based on the Merrifield\nexciton formalism. Using this model we study exciton transport in conjugated\npolymers and its dependence on morphology and temperature. Exciton dynamics\nconsists of a thermalisation process, whose features depend on the relative\nstrength of thermal energy, electronic couplings and disorder, resulting in\nremarkably different transport regimes. By applying this method to\nrepresentative systems based on poly(p-phenylene vinylene) (PPV) we obtain\ninsight into the role of temperature and disorder on localisation, charge\nseparation, non-equilibrium dynamics, and experimental accessibility of thermal\nequilibrium states of excitons in amorphous polymers."
    },
    {
        "anchor": "On the fundamentals of the three-dimensional translation gauge theory of\n  dislocations: We propose a dynamic version of the three-dimensional translation gauge\ntheory of dislocations. In our approach, we use the notions of the dislocation\ndensity and dislocation current tensors as translational field strengths and\nthe corresponding response quantities (pseudomoment stress, dislocation\nmomentum flux). We derive a closed system of field equations in a very elegant\nquasi-Maxwellian form as equations of motion for dislocations. In this\nframework, the dynamical Peach-Koehler force density is derived as well.\nFinally, the similarities and the differences between the Maxwell field theory\nand the dislocation gauge theory are presented.",
        "positive": "Mechanical properties of graphene oxide: the impact of functional groups: In the current study, mechanical characteristics of graphene oxide (GO) as a\npromising substitute of graphene are systematically studied through molecular\ndynamics simulation. For this purpose, several GO samples having different\nconcentrations of epoxide and hydroxyl functional groups are considered. The\nresults reveal that increasing the epoxide coverage causes a noticeable\ndeterioration in the mechanical characteristics of GO systems. This change is\ncorrelated with the increase of the formation of ripples in the structure upon\nincreasing the epoxide coverage. Moreover, investigating the bond lengths in\nthe system, it is concluded that the higher epoxide percentage leads to an\nincrease in the length of single and hybrid resonance bonds leading to an\noverall deterioration of the mechanical properties of GO samples. Additionally,\nour results demonstrate that high concentration of functional groups can lead\nto a negative Poisson ratio. Increasing the amount of hydroxyl groups shows the\nsame declining effect on the Young modulus. In a graphene system containing\nboth epoxide and hydroxyl groups, it is deduced that a higher percentage of the\nformer can result in a higher residual strain because of the formation of more\nripples within the system."
    },
    {
        "anchor": "Tailoring interfacial nanostructures at graphene/transition metal\n  dichalcogenide heterostructures: Integration of two-dimensional (2D) van der Waals (vdWs) materials with\nnon-2D materials to realize mixed-dimensional heterostructures has potential\nfor creating functional devices beyond the reach of existing materials and has\nlong been a pursuit of the material science community. Here we report the\npatterning of monolayer/bilayer transition metal dichalcogenide (TMD)\nnanostructures with nanometer-precision, tunable sizes and sites at interfaces\nof graphene/TMD heterostructures. Our experiments demonstrate that the TMD\nnanostructures can be created at selected positions of the interface using\nscanning tunneling microscope lithography and, more importantly, the sizes of\nthe interfacial TMD nanostructures can be tuned with nanoscale precise by\nmerging adjacent TMD nanostructures or by further tailoring. A structural phase\ntransition from hexagonal phase in bulk TMD to monoclinic phase in the\ninterfacial nanostructures is explicitly observed, which locally introduce\nwell-defined electrostatic potentials on graphene. These results not only\nenable the creation of high-quality patterned p-n junctions in vdWs\nheterostructures, but also provide a new route to realize custom-designed\nmixed-dimensional heterostructures.",
        "positive": "Determination of fast electron energy dependence of magic angles in\n  electron energy loss spectroscopy for anisotropic systems: We present an accurate determination of the magic angle conditions at which\nthe sample-orientation induced fine structure variation is eliminated in the\ncore-level electron energy loss spectroscopy of anisotropic systems. Our result\npaves the way for the application of magic angle electron energy loss\nspectroscopy (MAEELS) in material characterization. It also highlights, for the\nfirst time, the importance of the quantum interference effect between\nlongitudinal and transverse interactions for medium energy fast electrons, and\nits connection with the anisotropy of the electron transition."
    },
    {
        "anchor": "Global mapping of structures and properties of crystal materials: Understanding material composition-structure-function relationships is of\ncritical importance for the design and discovery of novel functional materials.\nWhile most such studies focus on individual materials, we conducted a global\nmapping study of all known materials deposited in the Material Project database\nto investigate their distributions in the space of a set of seven\ncompositional, structural, physical, and neural latent descriptors. These\ntwo-dimensional materials maps along with their density maps allow us to\nillustrate the distribution of the patterns and clusters of different shapes,\nwhich indicates the propensity of these materials and the tinkering history of\nexisting materials. We then overlap the material properties such as composition\nprototypes and piezoelectric properties over the background materials maps to\nstudy the relationships of how material compositions and structures affect\ntheir physical properties. We also use these maps to study the spatial\ndistributions of properties of known inorganic materials, in particular those\nof local vicinities in structural space such as structural density and\nfunctional diversity. These maps provide a uniquely comprehensive overview of\nmaterials and space and thus reveal previously undescribed fundamental\nproperties. Our methodology can be easily extended by other researchers to\ngenerate their own global material maps with different background maps and\noverlap properties for both distribution understanding and cluster-based new\nmaterial discovery. The source code for feature generation and generated maps\nare available at https://github.com/usccolumbia/matglobalmapping",
        "positive": "Structure and properties of functional oxide thin films: Insights from\n  electronic-structure calculations: The confluence of state-of-the-art electronic-structure computations and\nmodern synthetic materials growth techniques is proving indispensable in the\nsearch for and discovery of new functionalities in oxide thin films and\nheterostructures. Here, we review the recent contributions of\nelectronic-structure calculations to predicting, understanding, and discovering\nnew materials physics in thin-film perovskite oxides. We show that such\ncalculations can accurately predict both structure and properties in advance of\nfilm synthesis, thereby guiding the search for materials combinations with\nspecific targeted functionalities. In addition, because they can isolate and\ndecouple the effects of various parameters which unavoidably occur\nsimultaneously in an experiment -- such as epitaxial strain, interfacial\nchemistry and defect profiles -- they are able to provide new fundamental\nknowledge about the underlying physics. We conclude by outlining the\nlimitations of current computational techniques, as well as some important open\nquestions that we hope will motivate further methodological developments in the\nfield."
    },
    {
        "anchor": "Conductance and polarization in quantum junctions: We revisit the expression for the conductance of a general nanostructure --\nsuch as a quantum point contact -- as obtained from the linear response theory.\nWe show that the conductance represents the strength of the Drude singularity\nin the conductivity $\\sigma(k,k';i\\omega \\to 0)$. Using the equation of\ncontinuity for electric charge we obtain a formula for conductance in terms of\npolarization of the system. This identification can be used for direct\ncalculation of the conductance for systems of interest even at the {\\it\nab-initio} level. In particular, we show that one can evaluate the conductance\nfrom calculations for a finite system without the need for special\n``transport'' boundary conditions.",
        "positive": "Local structure, thermodynamics, and melting curve of boron phosphide at\n  high pressures by deep learning-driven ab initio simulations: Boron phosphide (BP) is a (super)hard semiconductor constituted of light\nelements, which is promising for high demand applications at extreme\nconditions. The behavior of BP at high temperatures and pressures is of special\ninterest but is also poorly understood because both experimental and\nconventional ab initio methods are restricted to studying refractory covalent\nmaterials. The use of machine learning interatomic potentials is a\nrevolutionary trend that gives a unique opportunity for high-temperature study\nof materials with ab initio accuracy. We develop a deep machine learning\npotential (DP) for accurate atomistic simulations of solid and liquid phases of\nBP as well as their transformations near the melting line. Our DP provides\nquantitative agreement with experimental and ab initio molecular dynamics data\nfor structural and dynamic properties. DP-based simulations reveal that at\nambient pressure tetrahedrally bonded cubic BP crystal melts into an open\nstructure consisting of two interpenetrating sub-networks of boron and\nphosphorous with different structures. Structure transformations of BP melts\nunder compressing are reflected by the evolution of low-pressure tetrahedral\ncoordination to high-pressure octahedral coordination. The main contributions\nto structural changes at low pressures are made by the evolution of\nmedium-range order in B-subnetwork and at high pressures by the change of\nshort-range order in P-sub-network. Such transformations exhibit an anomalous\nbehavior of structural characteristics in the range of 12--15 GPa. Analysis of\nthe results obtained raise open issues in developing machine learning\npotentials for covalent materials and stimulate further experimental and\ntheoretical studies of melting behavior in BP."
    },
    {
        "anchor": "Resolving Paradoxes of Classical Nucleation Theory: We present a new model of homogeneous aggregation that contains the essential\nphysical ideas of the classical predecessors, the Becker-Doring and\nLifshitz-Slyovoz models. These classical models, which give different\npredictions, are asymptotic limits of the new model at small (BD) and large\n(LS) cluster sizes. Since the new theory is valid for large and small clusters,\nit allows for a complete description of the nucleation process; one that can\npredict the creation of super-critical clusters at the Zeldovich nucleation\nrate, and the diffusion limited growth of large clusters during coarsening. By\nretaining the physically valid ingredients from both models, we explain the\nseeming incompatibilities and arbitrary choices of the classical models.",
        "positive": "Effect of silver doping on the electrical properties of a-Sb$_2$Se$_3$: This paper reports the effect of Ag-doping on electrical properties of\na-Sb2Se3 in the temperature range 240-340 K and frequency range 5 Hz to 100\nkHz. The variation of transport properties with thermal doping has been\nstudied. Ag-doping produced two homogeneous phases in the sample and which are\nfound to be voltage dependent in the temperature range studied and frequency\ndependent in lower frequency region (0.1 - 10 kHz). Activation energy Eg and C'\n[=$\\sigma_0$ exp ($\\gamma$/k), where $\\gamma$, is the temperature coefficient\nof the band gap] calculated from dc conductivity has been found to vary from\n0.42 eV to 0.26 eV and 41.08x10$^-6$ to 2.902x10-6 $\\ohm^{-1}$cm$^{-1}$\nrespectively. Ag-doping can be used to make the sample more useful in device\napplications."
    },
    {
        "anchor": "Origin of stabilization of macrotwin boundaries in martensites: The origin of stabilization of complex microstructures along macrotwin\nboundaries in martensites is explained by comparing two models based on\nGinzburg-Landau theory. The first model incorporates a geometrically nonlinear\nstrain tensor to ensure that the Landau energy is invariant under rigid body\nrotations, while the second model uses a linearized strain tensor under the\nassumption that deformations and rotations are small. We show that the\napproximation in the second model does not always hold for martensites and that\nthe experimental observations along macrotwin boundaries can only be reproduced\nby the geometrically nonlinear (exact) theory.",
        "positive": "Extrinsic contributions in a nonuniform ferroic sample: Dielectric,\n  piezoelectric and elastic: The contribution Delta_epsilon of extremely small motions of domain walls to\nsmall-signal permittivity of a multidomain ferroelectric sample has been a\nresearch issue for many years. In ferroelastic ferroelectrics such motions\ncontribute also to their piezoelectric (by Delta_d) and elastic (by Delta_s)\nproperties. Data about their simultaneous existence are scarce but those\navailable point to mutual proportionality of Delta_epsilon, Delta_d and\nDelta_s, as expected. To understand the magnitude of extrinsic contributions,\nthe origin of the restoring force acting on domain walls must be understood. In\nthe present contribution the theory has been developed based on the model of a\nplate-like sample in which the ferroelectric- ferroelastic bulk is provided\nwith a nonferroic surface layer. Motion of domain walls in the bulk results in\na change of electric and elastic energy both in the bulk and in the layer,\nwhich provides the source of restoring force. This makes it possible to\ndetermine all mentioned extrinsic contributions. We discuss the applicability\nof the model to available data for single crystals and also for ceramic grains."
    },
    {
        "anchor": "Magnetic phase diagram of Ce2Fe17: Rare-earth-based permanent-magnet materials rich in iron have relatively low\nferromagnetic ordering temperatures. This is believed to be due to the presence\nof antiferromagnetic exchange interactions, besides the ferromagnetic\ninteractions responsible for the magnetic order. The magnetic properties of\nCe2Fe17 are anomalous. Instead of ferromagnetic, it is antiferromagnetic, and\ninstead of one ordering temperature, it shows two, at the Neel temperature TN ~\n208 K and at TT ~ 124 K. Ce2Fe17, doped by 0.5% Ta, also shows two ordering\ntemperatures, one to an antiferromagnetic phase, at TN ~ 214 K, and one to a\nferromagnetic phase, at T0 ~ 75 K. In order to clarify this behavior,\nsingle-crystalline samples were prepared by solution growth, and characterized\nby electron microscopy, single crystal x-ray diffraction, temperature-dependent\nspecific heat, and magnetic field and temperature-dependent electrical\nresistivity and magnetization. From these measurements, magnetic H-T phase\ndiagrams were determined for both Ta-doped Ce2Fe17 and undoped Ce2Fe17. These\nphase diagrams can be very well described in terms of a theory that gives\nmagnetic phase diagrams of systems with competing antiferro- and\nferromagnetism.",
        "positive": "Role of Alloying-Atom Size Factor and System Shape Factor in Energetics\n  of bcc Fe under Macroscopic Deformation: We present an \\emph{ab initio} study of the effect of macroscopic deformation\non energetics of twelve alloying elements in bcc Fe under three specially\ndesigned strain modes. We find that there exists a universal linear relation of\ndescribing the volume dependence of substitutional energy of alloying elements\nvia introducing two factors --- the system shape factor ($f_{\\scriptsize{ss}}$)\nand the size factor of alloying element $M$ ($\\Omega^{M}_{\\scriptsize{sf}}$):\n$E_{\\scriptsize{sub}} \\sim f_{\\scriptsize{ss}}\\Omega^{M}_{\\scriptsize{sf}}V$.\n$\\Omega^{M}_{\\scriptsize{sf}}$ well describes the effect of intrinsic\nalloying-atom size and the influence of chemical interaction with matrix atom,\nand $f_{\\scriptsize{ss}}$ characterizes the degree of system lattice distortion\nunder deformation. This relation is further validated using the published data\nof stained-modulated doping in GaP"
    },
    {
        "anchor": "Dielectric screening at TMD:hBN interfaces: Monolayer-to-bulk\n  transition, local-field effect, and spatial dependence: The dielectric effects of a substrate have been shown to be important in\nmodulating the electronic properties of an adsorbate, especially in van der\nWaals heterostructures. Here, using the first-principles dielectric embedding\n$GW$ approach within the framework of many-body perturbation theory, we perform\na case study on the dielectric screening effects of hexagonal boron nitride\n(hBN) on various transition-metal dichalcogenides (TMDs). We consider three\nsystems: monolayer MoS$_2$, bilayer MoS$_2$, and mixed WS$_2$/MoS$_2$ bilayer\nadsorbed on hBN, and examine three aspects of the substrate dielectric\nscreening: (i) thickness dependence and the monolayer-to-bulk transition, where\nwe consider the effects of one-, two-, three-, and four-layer hBN; (ii)\nlocal-field effect, where we numerically assess a common approximation of\nneglecting the in-plane local-field components of the substrate polarizability;\nand (iii) spatial dependence, where we consider mixed WS$_2$/MoS$_2$ bilayer\nadsorbed on hBN with either side facing the substrate. Our results provide\nquantitative insight into how the substrate screening effects can be leveraged\nfor band structure engineering.",
        "positive": "Realization of the thermal equilibrium in inhomogeneous magnetic systems\n  by the Landau-Lifshitz-Gilbert equation with stochastic noise, and its\n  dynamical aspects: It is crucially important to investigate effects of temperature on magnetic\nproperties such as critical phenomena, nucleation, pinning, domain wall motion,\ncoercivity, etc. The Landau-Lifshitz-Gilbert (LLG) equation has been applied\nextensively to study dynamics of magnetic properties. Approaches of Langevin\nnoises have been developed to introduce the temperature effect into the LLG\nequation. To have the thermal equilibrium state (canonical distribution) as the\nsteady state, the system parameters must satisfy some condition known as the\nfluctuation-dissipation relation. In inhomogeneous magnetic systems in which\nspin magnitudes are different at sites, the condition requires that the ratio\nbetween the amplitude of the random noise and the damping parameter depends on\nthe magnitude of the magnetic moment at each site. Focused on inhomogeneous\nmagnetic systems, we systematically showed agreement between the stationary\nstate of the stochastic LLG equation and the corresponding equilibrium state\nobtained by Monte Carlo simulations in various magnetic systems including\ndipole-dipole interactions. We demonstrated how violations of the condition\nresult in deviations from the true equilibrium state. We also studied the\ncharacteristic features of the dynamics depending on the choice of the\nparameter set. All the parameter sets satisfying the condition realize the same\nstationary state (equilibrium state). In contrast, different choices of\nparameter set cause seriously different relaxation processes. We show two\nrelaxation types, i.e., magnetization reversals with uniform rotation and with\nnucleation."
    },
    {
        "anchor": "Diffusion of Zwitterion Glycine, Diglycine, and Triglycine in Water: Diffusion, transport of mass in response to concentration and thermal energy\ngradient, is an important transport property, vital in material science and\nlife science. In the present work classical molecular dynamics study of\ndiffusion of zwittterion glycine, zwitterion diglycine and zwitterion\ntriglycine in water have been carried out. Self and binary diffusion\ncoefficients of aqueous solution of these molecules have been calculated using\nEinstein method. Our results agree with experimental data reported in\nliteratures. Temperature dependency of diffusion of glycine in water have been\nexplored using estimated values of self and binary diffusion coefficients at\nfour different temperatures. Effect of peptide bond formation in diffusion has\nbeen studied using peptide chain composed of up to three monomers of glycine.\nThe structure of the system is analyzed using radial diestibution function of\ndifferent atom.",
        "positive": "GaN Nanowall Network: A new possible route to obtain efficient p-GaN and\n  enhanced light extraction: We demonstrate that GaN formed in a Nanowall Network (NwN) morphology can\novercome fundamental limitations in optoelectronic devices, and enable high\nlight extraction and effective Mg incorporation for efficient p-GaN. We report\nthe growth of Mg doped GaN Nanowall network (NwN) by plasma assisted molecular\nbeam epitaxy (PA-MBE) that is characterized by Photoluminescence (PL)\nspectroscopy, Raman spectroscopy, high-resolution X-ray diffraction (HR-XRD),\nX-ray photoelectron spectroscopy (XPS) and Secondary ion mass spectroscopy\n(SIMS). We record a photo-luminescence enhancement ($ \\approx $3.2 times) in\nlightly doped GaN as compared to that of undoped NwN. Two distinct (and broad)\nblue luminescence peaks appears at 2.95 and 2.7 eV for the heavily doped GaN\n(Mg $>10^{20}$ atoms $cm^{-3}$), of which the 2.95 eV peak is sensitive to\nannealing is observed. XPS and SIMS measurements estimate the incorporated Mg\nconcentration to be $10^{20}$ atoms $cm^{-3}$ in GaN NwN morphology, while\nretaining its band edge emission at $\\approx$ 3.4 eV. A higher Mg accumulation\ntowards the GaN/Al$_2$O$_3$ interface as compared to the surface was observed\nfrom SIMS measurements."
    },
    {
        "anchor": "Dynamical magnetic charges and linear magnetoelectricity: Magnetoelectric (ME) materials are of fundamental interest and have been\ninvestigated for their broad potential for technological applications. The\nsearch for, and eventually the theoretical design of, materials with large ME\ncouplings present challenging issues. First-principles methods have only\nrecently been developed to calculate the full ME response tensor $\\alpha$\nincluding both electronic and ionic (i.e., lattice-mediated) contributions. The\nlatter is proportional to both the Born dynamical electric charge $Z^{\\rm e}$\nand its analogue, the dynamical magnetic charge $Z^{\\rm m}$. Here we present a\ntheoretical study of the magnetic charge $Z^{\\rm m}$ and the mechanisms that\ncould enhance it. Using first-principles density-functional methods, we\ncalculate the atomic $Z^{\\rm m}$ tensors in $\\rm{Cr_2O_3}$, a prototypical\nmagnetoelectric, and in KITPite, a fictitious material that has previously been\nreported to show a strong ME response arising from exchange striction effects.\nOur results confirm that in $\\rm{Cr_2O_3}$, the $Z^{\\rm m}$ values and\nresulting ME responses arise only from spin-orbit coupling (SOC) and are\ntherefore rather weak. In KITPite, by contrast, the exchange striction acting\non the non-collinear spin structure induces much $Z^{\\rm m}$ values that\npersist even when SOC is completely absent.",
        "positive": "Unexpected coexisting solid solutions in the quasi-binary\n  Ag(II)F2/Cu(II)F2 phase diagram: High-temperature solid-state reaction between orthorhombic AgF2 and\nmonoclinic CuF2 (y = 0.15, 0.3, 0.4, 0.5) in a fluorine atmosphere resulted in\ncoexisting solid solutions of Cu-poor orthorhombic and Cu-rich monoclinic\nphases with stoichiometry Ag1-xCuxF2. Based on X-ray powder diffraction\nanalyses, the mutual solubility in the orthorhombic phase (AgF2 doped with Cu)\nappears to be at an upper limit of Cu concentration of 30 mol % (Ag0.7Cu0.3F2),\nwhile the monoclinic phase (CuF2 doped with Ag) can form a nearly\nstoichiometric Cu : Ag = 1 : 1 solid solution (Cu0.56Ag0.44F2), preserving the\nCuF2 crystal structure. Experimental data and DFT calculations showed that AgF2\ndoped with Cu and CuF2 doped with Ag solid solutions deviate from the classical\nVegards law. Magnetic measurements of Ag1-xCuxF2 showed that the Neel\ntemperature (TN) decreases with increasing Cu content in both phases. Likewise,\ntheoretical DFT+U calculations for Ag1-xCuxF2 showed that the progressive\nsubstitution of Ag by Cu decreases the magnetic interaction strength (J2D) in\nboth structures. Electrical conductivity measurements of Ag0.85Cu0.15F2 showed\na ca. 2-fold increase in specific ionic conductivity (3.71 x 10-13 plus/minus\n2.6 x 10-15 S/cm) as compared to pure AgF2 (1.85 x 10-13 plus/minus 1.2 x 10-15\nS/cm), indicating the formation of a vacancy- or F adatom-free metal difluoride\nsample."
    },
    {
        "anchor": "Proton-transfer Ferroelectricity / Multiferroicity in Rutile\n  Oxyhydroxides: Oxyhydroxide minerals like FeOOH have been a research focus in geology for\nstudying the Earth interior, and also in chemistry for studying oxygen\nelectrocatalysis activity. In this paper we provide first-principles evidence\nof a new class of ferroelectrics or multiferroics among\nthem:GaOOH,InOOH,CrOOH,FeOOH, which are earth-abundant minerals and have been\nexperimentally verified to possess distorted rutile structures, are\nferroelectric with considerable polarizations(up to 24 muC/cm2) and\npiezoelectric coefficients. Their atomic-thick layer may possess vertical\npolarization robust against depolarizing field due to the formation of O-H O\nbonds that can hardly be symmetrized. Moreover,CrOOH (guyanaite) is revealed to\nbe a combination of high-Tc in-plane type-I multiferroics and vertical type-II\nmultiferroics, which is strain-tunable and may render a desirable coupling\nbetween magnetism and ferroelectricity. Supported by experimental evidence on\nreversible conversion between metal oxyhydroxides and dioxides and their nice\nlattice match that renders convenient epitaxial growth, heterostructure\ncomposed of oxyhydroxides and prevalent metal dioxides (e.g. TiO2, SnO2 and\nCrO2) may be constructed for various applications like ferroelectric\nfield-effect transistors and multiferroic tunneling junctions.",
        "positive": "Sign change of the spin Hall effect due to electron correlation in\n  nonmagnetic CuIr alloys: Recently a positive spin Hall angle (SHA) of 0.021, was observed\nexperimentally in nonmagnetic CuIr alloys [Niimi et al., Phys. Rev. Lett. 106,\n126601 (2011)] and attributed predominantly to an extrinsic skew scattering\nmechanism, while a negative SHA was obtained from ab initio calculations\n[Fedorov et al., Phys. Rev. B 88, 085116 (2013)], using consistent definitions\nof the SHA. We reconsider the SHA in CuIr alloys, with the effects of the local\nelectron correlation U in 5d orbitals of Ir impurities, included by the quantum\nMonte Carlo method. We found that the SHA is negative if we ignore such local\nelectron correlation, but becomes positive once U approaches a realistic value.\nThis may open up a way to control the sign of the SHA by manipulating the\noccupation number of impurities."
    },
    {
        "anchor": "Intrinsic Optical Transition Energies in Carbon Nanotubes: Intrinsic optical transition energies for isolated and individual single wall\ncarbon nanotubes grown over trenches are measured using tunable resonant Raman\nscattering. Previously measured E22_S optical transitions from nanotubes in\nsurfactants are blue shifted 70-90 meV with respect to our measurements of\nnanotubes in air. This large shift in the exciton energy is attributed to a\nlarger change of the exciton binding energy than the band-gap renormalization\nas the surrounding dielectric constant increases.",
        "positive": "Bandgap widening and behavior of Raman-active phonon modes of cubic\n  single-crystalline (In,Ga)$_2$O$_3$ alloy films: The influence of Ga incorporation into cubic In$_2$O$_3$ on the electronic\nand vibrational properties is discussed for (In$_{1-x}$,Ga$_x$)$_2$O$_3$ alloy\nfilms grown by molecular beam epitaxy. Using spectroscopic ellipsometry, a\nlinear dependence of the absorption onset on the Ga content $x$ is found with a\nblueshift of up to 150 meV for $x = 0.1$. Consistently, the fundamental band\ngap exhibits a blueshift as determined by hard X-ray photoelectron\nspectroscopy. The dependence of the absorption onset and the effective electron\nmass on the electron concentration is derived from the infrared dielectric\nfunctions for a Sn doped alloy film. The influence of alloying on phonon modes\nis analyzed on the basis of Raman spectroscopic measurements. The frequencies\nof several phonon modes are identified as sensitive measures for the\nspectroscopic determination of the Ga content."
    },
    {
        "anchor": "Electronic structure and optical properties of quantum confined\n  lead-salt nanowires: In the framework of four-band envelope-function formalism, developed earlier\nfor spherical semiconductor nanocrystals, we study the electronic structure and\noptical properties of quantum-confined lead-salt (PbSe and PbS) nanowires (NWs)\nwith a strong coupling between the conduction and the valence bands. We derive\nspatial quantization equations, and calculate numerically energy levels of\nspatially quantized states of a transverse electron motion in the plane\nperpendicular to the NW axis, and electronic subbands developed due to a free\nlongitudinal motion along the NW axis. Using explicit expressions for\neigenfunctions of the electronic states, we also derive analytical expressions\nfor matrix elements of optical transitions and study selection rules for\ninterband absorption.\n  Next we study a two-particle problem with a conventional long-range Coulomb\ninteraction and an interparticle coupling via medium polarization. The obtained\nresults show that due to a large magnitude of the high-frequency dielectric\npermittivity of PbSe material, and hence, a high dielectric NW/vacuum contrast,\nthe effective coupling via medium polarization significantly exceeds the\neffective direct Coulomb coupling at all interparticle separations along the NW\naxis. Furthermore, the strong coupling via medium polarization results in a\nbound state of the longitudinal motion of the lowest-energy electron-hole pair\n(a longitudinal exciton), while fast transverse motions of charge carriers\nremain independent of each other.",
        "positive": "Origin of the orbital polarization of Co$^{2+}$ in La$_2$CoTiO$_6$ and\n  (LaCoO$_3$)$_1$+(LaTiO$_3$)$_1$ : a DFT+$U$ and DMFT study: The unequal electronic occupation of localized orbitals (orbital\npolarization), and associated lowering of symmetry and degeneracy, play an\nimportant role in the properties of transition metal oxides. Here, we examine\nsystematically the underlying origin of orbital polarization, taking as\nexemplar the 3$d$ manifold of Co$^{2+}$ in a variety of spin, orbital and\nstructural phases in the double perovskite La$_2$CoTiO$_6$ and the (001)\nsuperlattice (LaCoO$_3$)$_1$+(LaTiO$_3$)$_1$ systems. Superlattices are of\nspecific interest due to the large experimentally observed orbital polarization\nof their Co cations. Based on first principles calculations, we find that\nrobust and observable orbital polarization requires symmetry reduction through\nthe lattice structure; the role of local electronic interactions is to greatly\nenhance the orbital polarization."
    },
    {
        "anchor": "A low-surface energy carbon allotrope: the case for bcc-C6: Graphite may be viewed as a low-surface-energy carbon allotrope with little\nlayer-layer interaction. Other low-surface-energy allotropes but with much\nstronger layer-layer interaction may also exist. Here, we report a\nfirst-principles prediction for one of the known carbon allotropes, bcc-C6 (a\nbody centered carbon allotrope with six atoms per primitive unit) that should\nhave exceptionally low-surface energy and little size dependence down to only a\ncouple layer thickness. This unique property may explain the existence of the\nrelatively-high-energy bcc-C6 during growth. The electronic properties of the\nbcc-C6thin layers can also be intriguing: the (111), (110), and (001) thin\nlayers havedirect band gap, indirect band gap, and metallic character,\nrespectively. The refrained chemical reactivity of the thin layers does not\ndisappear after cleaving, as lithium-doped (Li-doped) 3-layers (111) has a\nnoticeably increased binding energies of H2 molecules with a maximum storage\ncapacity of 10.8 wt%.",
        "positive": "Piezoelectricity in Nominally Centrosymmetric Phases: Compound phases often display properties that are symmetry-forbidden relative\nto their nominal, average crystallographic symmetry, even if extrinsic reasons\n(defects, strain, imperfections) are not apparent. Here, we investigate\nmacroscopic inversion symmetry breaking in nominally centrosymmetric materials\nand measure Resonant Piezoelectric Spectroscopy (RPS) and Resonant Ultrasound\nSpectroscopy (RUS) in 15 compounds, 18 samples, and 21 different phases,\nincluding unpoled ferroelectrics, paraelectrics, relaxors, ferroelastics,\nincipient ferroelectrics, and isotropic materials with low defect\nconcentrations, i.e. NaCl,cfused silica, and CaF2. We exclude the flexoelectric\neffect as a source of the observed piezoelectricity yetcobserve\npiezoelectricity in all nominally cubic phases of these samples. By scaling the\nRPS intensities with those of RUS, we calibrate the effective piezoelectric\ncoefficients using single crystal quartz as standard. Using this scaling we\ndetermine the effective piezoelectric modulus in nominally non-piezoelectric\nphases, finding that the \"symmetry-forbidden\" piezoelectric effect ranges from\n1 pm/V to 10E-5 pm/V. The values for unpoled ferroelectric phases are only\nslightly higher than those in the paraelectric phase of the same material. The\nlowest coefficients are well below the detection limit of conventional\npiezoelectric measurements and demonstrate RPS as an ultra-highly sensitive\nmethod to measure piezoelectricity. We suggestt hat symmetry-breaking\npiezoelectricity in nominally centrosymmetric materials and disordered, unpoled\nferroelectrics is ubiquitous."
    },
    {
        "anchor": "Softening of ultra-nanocrystalline diamond at low grain sizes: Ultra-nanocrystalline diamond is a polycrystalline material, having\ncrystalline diamond grains of sizes in the nanometer regime. We study the\nstructure and mechanical properties of this material as a function of the\naverage grain size, employing atomistic simulations. From the calculated\nelastic constants and the estimated hardness, we observe softening of the\nmaterial as the size of its grains decreases. We attribute the observed\nsoftening to the enhanced fraction of interfacial atoms as the average grain\nsize becomes smaller. We provide a fitting formula for the scaling of the\ncohesive energy and bulk modulus with respect to the average grain size. We\nfind that they both scale as quadratic polynomials of the inverse grain size.\nOur formulae yield correct values for bulk diamond in the limit of large grain\nsizes.",
        "positive": "Reversible Ferromagnetic Switching in Zno:(Co,Mn) Powders: We report here on the magnetic properties of ZnO:Mn and ZnO:Co doped\nnanoparticles. We have found that the ferromagnetism of ZnO:Mn can be switched\non and off by consecutive low-temperature annealings in O2 and N2 respectively,\nwhile the opposite phenomenology was observed for ZnO:Co. These results suggest\nthat different defects (presumably n-type for ZnO:Co and p-type for ZnO:Mn) are\nrequired to induce a ferromagnetic coupling in each case. We will argue that\nferromagnetism is likely to be restricted to a very thin, nanometric layer, at\nthe grain surface. These findings reveal and give insight into the dramatic\nrelevance of surface effects for the occurrence of ferromagnetism in ZnO doped\noxides."
    },
    {
        "anchor": "Diffusion and submonolayer island growth during hyperthermal deposition\n  on Cu(100) and Cu(111): We consider the influence of realistic island diffusion rates to\nhomoepitaxial growth on metallic surfaces using a recently developed rate\nequation model which describes growth in the submonolayer regime with\nhyperthermal deposition. To this end, we incorporate realistic size and\ntemperature-dependent island diffusion coefficients for the case of\nhomoepitaxial growth on Cu(100) and Cu(111) surfaces. We demonstrate that the\ngeneric features of growth remain unaffected by the details of island\ndiffusion, thus validating the generic scenario of high density of small\nislands found experimentally and theoretically for large detachment rates.\nHowever, the details of the morphological transition and scaling of the mean\nisland size are strongly influenced by the size dependence of island diffusion.\nThis is reflected in the scaling exponent of the mean island size, which\ndepends on both temperature and the surface geometry.",
        "positive": "A probabilistic deep learning approach to automate the interpretation of\n  multi-phase diffraction spectra: Autonomous synthesis and characterization of inorganic materials requires the\nautomatic and accurate analysis of X-ray diffraction spectra. For this task, we\ndesigned a probabilistic deep learning algorithm to identify complex\nmulti-phase mixtures. At the core of this algorithm lies an ensemble\nconvolutional neural network trained on simulated diffraction spectra, which\nare systematically augmented with physics-informed perturbations to account for\nartifacts that can arise during experimental sample preparation and synthesis.\nLarger perturbations associated with off-stoichiometry are also captured by\nsupplementing the training set with hypothetical solid solutions. Spectra\ncontaining mixtures of materials are analyzed with a newly developed branching\nalgorithm that utilizes the probabilistic nature of the neural network to\nexplore suspected mixtures and identify the set of phases that maximize\nconfidence in the prediction. Our model is benchmarked on simulated and\nexperimentally measured diffraction spectra, showing exceptional performance\nwith accuracies exceeding those given by previously reported methods based on\nprofile matching and deep learning. We envision that the algorithm presented\nhere may be integrated in experimental workflows to facilitate the\nhigh-throughput and autonomous discovery of inorganic materials."
    },
    {
        "anchor": "Enhanced Catalytic Activity in Strained Chemically Exfoliated WS2\n  Nanosheets for Hydrogen Evolution: The ability to efficiently evolve hydrogen via electrocatalysis at low\noverpotentials holds tremendous promise for clean energy. Hydrogen evolution\nreaction (HER) can be easily achieved from water if a voltage above the\nthermodynamic potential of the HER is applied. Large overpotentials are\nenergetically inefficient but can be lowered with expensive platinum based\ncatalysts. Replacement of Pt with inexpensive, earth abundant electrocatalysts\nwould be significantly beneficial for clean and efficient hydrogen evolution.\nTowards this end, promising HER characteristics have been reported using 2H\n(trigonal prismatic) XS2 (where X = Mo or W) nanoparticles with a high\nconcentration of metallic edges as electrocatalysts. The key challenges for HER\nwith XS2 are increasing the number and catalytic activity of active sites. Here\nwe report atomically thin nanosheets of chemically exfoliated WS2 as efficient\ncatalysts for hydrogen evolution with very low overpotentials.\nAtomic-resolution transmission electron microscopy and spectroscopy analyses\nindicate that enhanced electrocatalytic activity of WS2 is associated with high\nconcentration of strained metallic 1T (octahedral) phase in the as-exfoliated\nnanosheets. Density functional theory calculations reveal that the presence of\nstrain in the 1T phase leads to an enhancement of the density of states at the\nFermi level and increases the catalytic activity of the WS2 nanosheet. Our\nresults suggest that chemically exfoliated WS2 nanosheets could be interesting\ncatalysts for hydrogen evolution.",
        "positive": "Co-existence of size-dependent and size-independent thermal\n  conductivities in single layer black phosphorus: Thermal conductivity of single layer black phosphorus (BP) is investigated by\ncombining density functional calculations and Peierls-Boltzmann transport\nequation. Differing from isotropic and divergent thermal conductivities in\ntwo-dimensional graphene and MoS$_2$, an compelling co-existence of\nsize-dependent and size-independent thermal conductivities are discovered for\nsingle layer BP along zigzag (ZZ) and armchair (AM) direction, respectively.\nBesides, thermal conductivities in single layer BP are found to be highly\nanisotropic because of orientation dependent group velocities, e.g., thermal\nconductivities at 300 K are 83.5 and 24.3 W/m-K along ZZ and AM directions for\nsingle layer BP with a size of 10 $\\mu m$, respectively."
    },
    {
        "anchor": "Monitoring in real time the photon-dressing and undressing of\n  quasiparticles from first principles time-resolved photoelectron spectroscopy: Optical pumping of solids creates a non-equilibrium electronic structure\nwhere electrons and photons combine to form quasiparticles of dressed\nelectronic states. The resulting shift of electronic levels is known as the\noptical Stark effect, visible as a red shift in the optical spectrum. Here we\nshow that in a pump-probe setup we can uniquely define a non-equilibrium\nquasiparticle bandstructure that can be directly measurable with photo-electron\nspectroscopy. The dynamical photon-dressing (and undressing) of the many-body\nelectronic states can be monitored by pump-probe time and angular resolved\nphotoelectron spectroscopy (tr-ARPES) as the photon-dressed bandstructure\nevolves in time depending on the pump-probe pulse overlap. The computed\ntr-ARPES spectrum agrees perfectly with the quasi-energy spectrum of Floquet\ntheory at maximum overlap and goes to the the equilibrium bandstructure as the\npump-probe overlap goes to zero. Additionally, we show how this time-dependent\nnon-equilibrium quasiparticle structure can be understood to be the\nbandstructure underlying the optical Stark effect. The extension to\nspin-resolved PES can be used to predict asymmetric dichroic response linked to\nthe valley selective optical excitations in monolayer transition metal\ndichalcogenides (TMDs).",
        "positive": "Large spin-mixing conductance in highly Bi-doped Cu thin films: Spin Hall effect provides an efficient tool for the conversion of a charge\ncurrent into a spin current, opening the possibility of producing pure spin\ncurrents in non-magnetic materials for the next generation of spintronics\ndevices. In this sense, giant Spin Hall Effect has been recently reported in Cu\ndoped with 0.5 % Bi grown by sputtering and larger values are expected for\nlarger Bi doping, according to first principles calculations. In this work we\ndemonstrate the possibility of doping Cu with up to 10 % of Bi atoms without\nevidences of Bi surface segregation or cluster formation, as studied by\ndifferent microscopic and spectroscopic techniques. In addition, YIG/BiCu\nstructures have been grown, showing a spin mixing conductance larger that the\none shown by similar Pt/YIG structures. These results reflects the potentiality\nof these new materials in spintronics devices."
    },
    {
        "anchor": "Machine learning in nuclear materials research: Nuclear materials are often demanded to function for extended time in extreme\nenvironments, including high radiation fluxes and transmutation, high\ntemperature and temperature gradients, stresses, and corrosive coolants. They\nalso have a wide range of microstructural and chemical makeup, with\nmultifaceted and often out-of-equilibrium interactions. Machine learning (ML)\nis increasingly being used to tackle these complex time-dependent interactions\nand aid researchers in developing models and making predictions, sometimes with\nbetter accuracy than traditional modeling that focuses on one or two parameters\nat a time. Conventional practices of acquiring new experimental data in nuclear\nmaterials research are often slow and expensive, limiting the opportunity for\ndata-centric ML, but new methods are changing that paradigm. Here we review\nhigh-throughput computational and experimental data approaches, especially\nrobotic experimentation and active learning that based on Gaussian process and\nBayesian optimization. We show ML examples in structural materials ( e.g.,\nreactor pressure vessel (RPV) alloys and radiation detecting scintillating\nmaterials) and highlight new techniques of high-throughput sample preparation\nand characterizations, and automated radiation/environmental exposures and\nreal-time online diagnostics. This review suggests that ML models of material\nconstitutive relations in plasticity, damage, and even electronic and optical\nresponses to radiation are likely to become powerful tools as they develop.\nFinally, we speculate on how the recent trends in artificial intelligence (AI)\nand machine learning will soon make the utilization of ML techniques as\ncommonplace as the spreadsheet curve-fitting practices of today.",
        "positive": "Volume-shear coupling in a mesoscopic model of amorphous materials: We present a two-dimensional mesoscopic model of a yield stress material that\nincludes the possibility of local volume fluctuations coupled to shear, in such\na way that the shear strength of the material decreases as the local density\ndecreases. The model reproduces a number of effects well known in the\nphenomenology of this kind of materials. Particularly, we find that: the volume\nof the sample increases as the deformation rate increases; shear bands are no\nlonger oriented at 45 $^\\circ$ with respect to the principal axis of the\napplied stress (as in the absence of volume-shear coupling); homogeneous\ndeformation becomes unstable at low enough deformation rates if volume-shear\ncoupling is strong enough. We also analyze the implications of this coupling in\nthe context of out of equilibrium shear bands appearing for instance in\nmetallic glasses."
    },
    {
        "anchor": "Mapping different skyrmion phases in double wedges of\n  Ta/FeCoB(tFeCoB)/Ta(tTa)Ox: Skyrmions are chiral magnetic textures that have immense potential for\napplications in spintronic devices. However, their formation is quite\nchallenging and necessitates a subtle balance of the magnetic interactions at\nplay. Here, we study Ta/FeCoB/TaOx trilayer using crossed double wedges i.e.\nthickness gradients of FeCoB and of top Ta, which is subsequently oxidized\nleading to an oxidation gradient. This enabled us to observe micron-sized\nskyrmions in the vicinity of different transition regions of the sample: from\nperpendicular magnetic anisotropy to paramagnetic phase and also from\nperpendicular to in-plane magnetic anisotropy. These observations can be\nexplained by the isolated bubble model taking into account the different energy\ncontributions at play namely anisotropy, exchange, Dzyaloshinskii-Moriya,\ndipolar and Zeeman. We also qualitatively compare the current-induced motion of\nskyrmions obtained in different transition regions. Our study not only provides\nan effective means to form skyrmions by tuning the interfacial magnetic\nproperties but also highlights the differences pertaining to the skyrmions\nobserved in different transition zones, which is extremely crucial for any\nenvisaged application.",
        "positive": "Soft modes in two- and eight-direction order-disorder ferroelectrics: The soft modes in the two- and eight-direction order-disorder ferroelectrics\nare calculated under the mean-field approximation. We find that the\nconventional method of the pseudospin model to calculate the soft-mode\nfrequency is incorrect, and present a valid modified method. It is demonstrated\nthat the conventional method does not show the soft-mode frequency going to\nzero at a critical temperature in the presence of random internal fields, while\nthe frequency calculated by our modified method goes to zero in random fields\nat a critical temperature. In the eight-direction ferroelectrics, the soft-mode\nfrequency decreases to zero at the first-order phase transition temperature\nthough the symmetry has been destroyed at high temperatures under an external\nfield. The promotion effect of random fields on the phase transition is\ntestified by the calculation results of the soft modes in the paraelectric\nphase."
    },
    {
        "anchor": "Searching for topological Fermi arcs via quasiparticle interference on a\n  type-II Weyl semimetal MoTe$_2$: Weyl semimetals display a novel topological phase of matter where the Weyl\nnodes emerge in pairs of opposite chirality and can be seen as either a source\nor a sink of Berry curvature. The exotic effects in Weyl semimetals, such as\nsurface Fermi arcs and the chiral anomaly, make them a new playground for\nexploring novel functionalities. Further exploiting their potential\napplications requires clear understanding of their topological electronic\nproperties, such as Weyl points and Fermi arcs. Here we report a Fourier\ntransform scanning tunneling spectroscopy (FT-STS) study on a type-II Weyl\nsemimetal candidate MoTe$_2$ whose Weyl points are predicated to be located\nabove Fermi level. Although its electronic structure below the Fermi level have\nbeen identified by angle resolved photo emission spectroscopy (ARPES), by\ncomparing our experimental data with first-principles calculations, we are able\nto identify the origins of the multiple scattering channels at energies both\nbelow and above Fermi level. Our calculations also show the existence of both\ntrivial and topological arc like states above the Fermi energy. In the FT-STS\nexperiments, we have observed strong signals from intra-arc scatterings as well\nas from the scattering between the arc-like surface states and the projected\nbulk states. A detailed comparison between our experimental observations and\ncalculated results reveals the trivial and non-trivial scattering channels are\ndifficult to distinguish in this compound. Interestingly, we find that the\nbroken inversion symmetry changes the terminating states on the two\ninequivalent surfaces, which in turn changes the relative strength of the\nscattering channels observed in the FT-STS images on the two surfaces.",
        "positive": "Thermal Raman study of Li4Ti5O12 and discussion about the number of its\n  characteristic bands: Lithium battery industry is booming, and this fast growth should be supported\nby developing industry friendly tools to control the quality of positive and\nnegative electrode materials. Raman spectroscopy was shown to be a cost\neffective and sensitive instrument to study defects and heterogeneities in\nlithium titanate, popular negative electrode material for high power\napplications, but there are still some points to be clarified. This work\npresents a detailed thermal Raman study for lithium titanate and discusses the\ndifference of the number of predicted and experimentally observed Raman-active\nbands. The low temperature study and the analysis of thermal shifts of bands\npositions during heating let us to conclude about advantages of the proposed\napproach with surplus bands and recommend using shifts of major band to\nestimate the sample heating."
    },
    {
        "anchor": "Screw dislocations in BCC transition metals: from ab initio modeling to\n  yield criterion: We show here how density functional theory calculations can be used to\npredict the temperatureand orientation-dependence of the yield stress of\nbody-centered cubic (BCC) metals in the thermallyactivated regime where\nplasticity is governed by the glide of screw dislocations with a 1/2 <111>\nBurgers vector. Our numerical model incorporates non-Schmid effects, both the\ntwinning/antitwinning asymmetry and non-glide effects, characterized through ab\ninitio calculations on straight dislocations. The model uses the\nstress-dependence of the kink-pair nucleation enthalpy predicted by a line\ntension model also fully parameterized on ab initio calculations. The\nmethodology is illustrated here on BCC tungsten but is applicable to all BCC\nmetals. Comparison with experimental data allows to highlight both the\nsuccesses and remaining limitations of our modeling approach.",
        "positive": "Electric field and exciton structure in CdSe nanocrystals: Quantum Stark effect in semiconductor nanocrystals is theoretically\ninvestigated, using the effective mass formalism within a $4\\times 4$\nBaldereschi-Lipari Hamiltonian model for the hole states. General expressions\nare reported for the hole eigenfunctions at zero electric field. Electron and\nhole single particle energies as functions of the electric field\n($\\mathbf{E}_{QD}$) are reported. Stark shift and binding energy of the\nexcitonic levels are obtained by full diagonalization of the correlated\nelectron-hole Hamiltonian in presence of the external field. Particularly, the\nstructure of the lower excitonic states and their symmetry properties in CdSe\nnanocrystals are studied. It is found that the dependence of the exciton\nbinding energy upon the applied field is strongly reduced for small quantum dot\nradius. Optical selection rules for absorption and luminescence are obtained.\nThe electric-field induced quenching of the optical spectra as a function of\n$\\mathbf{E}_{QD}$ is studied in terms of the exciton dipole matrix element. It\nis predicted that photoluminescence spectra present anomalous field dependence\nof the emission lines. These results agree in magnitude with experimental\nobservation and with the main features of photoluminescence experiments in\nnanostructures."
    },
    {
        "anchor": "Versatile electronic properties and exotic edge states in single-layer\n  tetragonal silicon carbides: Three single-layer tetragonal silicon carbides (SiC), termed as T1,T2 and T3,\nare proposed by density functional theory (DFT) computations. Although the\nthree structures have the same topological geometry, they show versatile\nelectronic properties from semiconductor (T1), semimetal (T2) to metal (T3).The\nversatile properties are originated from the rich bonds between Si and C atoms.\nThe nanoribbons of the three SiC also show interesting electronic properties.\nEspecially, T1 nanoribbons possess exotic edge states, where electrons only\ndistribute on one edge's silicon or carbon atoms. The band gaps of the T1\nnanoribbons are constant because of no interaction between the edge states.",
        "positive": "Interfacial nanostructure induced spin-reorientation transition in\n  Ni/Fe/Ni/W(110): We investigated the mechanism of the spin-reorientation transition (SRT) in\nthe Ni/Fe/Ni/W(110) system using in situ low-energy electron microscopy, x-ray\nmagnetic circular dichroism measurements, and first principles electronic\nstructure calculations. We discovered that the growth of Fe on a flat Ni film\non a W (110) crystal resulted in the formation of nanosized particles, instead\nof a uniform monolayer of Fe as commonly assumed. This interfacial\nnanostructure leads to a change of the system's dimensionality from two\ndimensional- to three dimensional-like, which simultaneously weakens the\ndipolar interaction and enhances the spin-orbit coupling in the system and\ndrives the observed SRT."
    },
    {
        "anchor": "Chemical Short-Range Ordering in a CrCoNi Medium-Entropy Alloy: The exceptional mechanical strengths of medium and high-entropy alloys have\nbeen attributed to hardening in random solid solutions. Here, we evidence\nnon-random chemical mixings in CrCoNi alloys, resulting from short range\nordering. A novel data-mining approach of electron nanodiffraction patterns\nenabled the study, which is assisted by neutron scattering, atom probe\ntomography, and diffraction simulation using first principles theory models.\nResults reveal two critical types of short range orders in nanoclusters that\nminimize the Cr and Cr nearest neighbors (L11) or segregate Cr on alternating\nclose-packed planes (L12). The makeup of ordering-strengthened nanoclusters can\nbe tuned by heat treatments to affect deformation mechanisms. These findings\nuncover a mixture of bonding preferences and their control at the nanoscopic\nscale in CrCoNi and provide general opportunities for an atomistic-structure\nstudy in concentrated alloys for the design of strong and ductile materials.",
        "positive": "EPW: Electron-phonon coupling, transport and superconducting properties\n  using maximally localized Wannier functions: The EPW (Electron-Phonon coupling using Wannier functions) software is a\nFortran90 code that uses density-functional perturbation theory and maximally\nlocalized Wannier functions for computing electron-phonon couplings and related\nproperties in solids accurately and efficiently. The EPW v4 program can be used\nto compute electron and phonon self-energies, linewidths, electron-phonon\nscattering rates, electron-phonon coupling strengths, transport spectral\nfunctions, electronic velocities, resistivity, anisotropic superconducting gaps\nand spectral functions within the Migdal-Eliashberg theory. The code now\nsupports spin-orbit coupling, time-reversal symmetry in non-centrosymmetric\ncrystals, polar materials, and $\\mathbf{k}$ and $\\mathbf{q}$-point\nparallelization. Considerable effort was dedicated to optimization and\nparallelization, achieving almost a ten times speedup with respect to previous\nreleases. A computer test farm was implemented to ensure stability and\nportability of the code on the most popular compilers and architectures. Since\nApril 2016, version 4 of the EPW code is fully integrated in and distributed\nwith the Quantum ESPRESSO package, and can be downloaded through QE-forge at\nhttp://qe-forge.org/gf/project/q-e."
    },
    {
        "anchor": "Precursor of the premartensite in Ni2MnGa magnetic shape memory alloy: A\n  pair distribution function study: Precursor phenomena observed prior to the martensite phase transition plays a\ncritical role towards the understanding of important technological properties\nof shape memory and magnetic shape memory alloys (MSMAs). The premartensite\n(PM) phase, considered as the precursor state of the martensite is proven to be\na thermodynamically stable phase recently (Nature Commun. 8, 1006 (2017)),\nnecessitates a critical investigation of precursor effects in these materials.\nWe present here an evidence for the existence of a precursor state of the PM\nphase in Ni2MnGa MSMA using high energy synchrotron pair distribution function\n(PDF) study. The precursor state embedded within the austenite matrix in the\nshort-range ordered (SRO) regime starting from far above the actual PM phase\ntransition. The presence of such SRO precursor states of the PM phase produces\nstrains which couple with the ferromagnetic (FM) order parameter around TC\nleading to first order character of the paramagnetic to FM phase transition.",
        "positive": "Perspectives of Racetrack Memory for Large-Capacity On-Chip Memory: From\n  Device to System: Current-induced domain wall motion (CIDWM) is regarded as a promising way\ntowards achieving emerging high-density, high-speed and low-power non-volatile\ndevices. Racetrack memory is an attractive spintronic memory based on this\nphenomenon, which can store and transfer a series of data along a magnetic\nnanowire. However, storage capacity issue is always one of the most serious\nbottlenecks hindering its application for practical systems. This paper focuses\non the potential of racetrack memory towards large capacity. The investigations\ncovering from device level to system level have been carried out. Various\nalternative mechanisms to improve the capacity of racetrack memory have been\nproposed and elucidated, e.g. magnetic field assistance, chiral DW motion and\nvoltage-controlled flexible DW pinning. All of them can increase nanowire\nlength, allowing enhanced feasibility of large-capacity racetrack memory. By\nusing SPICE compatible racetrack memory electrical model and commercial CMOS 28\nnm design kit, mixed simulations are performed to validate their\nfunctionalities and analyze their performance. System level evaluations\ndemonstrate the impact of capacity improvement on overall system. Compared with\ntraditional SRAM based cache, racetrack memory based cache shows its advantages\nin terms of execution time and energy consumption."
    },
    {
        "anchor": "Theory of defect-mediated ionic transport in Li, Na and K beta and beta\n  prime prime aluminas: Alkali metal $\\beta$/$\\beta^{\\prime\\prime}$ aluminas are among the fastest\nionic conductors, yet little is understood about the role of defects in the ion\ntransport mechanism. Here, we use density functional theory (DFT) to\ninvestigate the crystal structures of $\\beta$ and $\\beta^{\\prime\\prime}$\nphases, and vacancy and interstitial defects in these materials. We find that\ncharge transport is likely to be dominated by alkali metal interstitials in\n$\\beta$-aluminas and by vacancies in $\\beta^{\\prime\\prime}$ aluminas. Lower\nbounds for the activation energy for diffusion are found by determining the\nminimum energy paths for defect migration. The resulting migration barriers are\nlower than the experimental activation energies for conduction in Na $\\beta$\nand $\\beta^{\\prime\\prime}$ aluminas, suggesting a latent potential for\noptimization. The lowest activation energy of about 20 meV is predicted for\ncorrelated vacancy migration in K $\\beta^{\\prime\\prime}$ alumina.",
        "positive": "Structure, Electrical and Optical Properties of ITO Thin Films and their\n  Influence on Performance of CdS/CdTe Thin-Film Solar Cells: In terms of mixing graded TiO2 and SnO2 powders by solid-state reaction\nmethod, ITO was prepared. Using electron beam gun technology, ITO films with\ndifferent thicknesses were prepared. The influence of film thickness on\nstructure, electrical and optical properties was studied. The XRD patterns were\nutilized to determine the structural parameters (lattice strain and crystallite\nsize) of ITO with different thicknesses. It is observed that the average\ncrystallite size increases as the film thickness increases, but the lattice\nstrain decreases. SEM shows that as the film thickness increases, the grain\nsize of ITO increases and improves. The electrical properties of ITO films with\ndifferent thicknesses were measured by the standard four-point probe method. It\ncan be seen that as the thickness of the ITO film increases from 75 nm to 325\nnm, the resistivity decreases from 29x10^-4 Ohm/cm to 1.65x10^-4 Ohm/cm. This\nmeans that ITO films with lower electrical properties will be more suitable for\nhigh-efficiency CdTe solar cells. Three optical layer models (adhesive layer of\nthe substrate/B-spline layer of ITO film/surface roughness layer) are used to\ncalculate the film thickness with high-precision ellipsometry. In the higher\nT(lambda) and R(lambda) absorption regions, the absorption coefficient is\ndetermined to calculate the optical energy gap, which increases from 3.56 eV to\n3.69 eV. Finally, the effects of ITO layers of various thicknesses on the\nperformance of CdS/CdTe solar cells are also studied. When the thickness of the\nITO window layer is 325 nm, Voc = 0.82 V, Jsc = 17 mA/cm2, and FF = 57.4%, the\nhighest power conversion efficiency (PCE) is 8.6%."
    },
    {
        "anchor": "A general rule for predicting the magnetic moment of Cobalt-based\n  Heusler compounds using compressed sensing and density functional theory: We propose a general rule for estimating the magnetic moments of Co$\n2$(cobalt)-based Heusler alloys, especially when doped with late transition\nmetals. We come up with a descriptor that can characterise both pure Co$_2$YZ\ncompounds and the doped ones with the chemical formula Co$_2$Y$_{1-x}$M$_x$Z (M\nis the dopant) using online data for magnetic moments of Heusler alloys with\nCo$_2$YZ structure and compressive sensing approach. The newly proposed\ndescriptor not only depends on the number of valence electrons of the compound\nalso it depends on the number of unoccupied d-electrons in the doping site. A\ncomparison of the performance of the proposed descriptor and the Slater-Pauling\nrule is made. Unlike the Slater-Pauling rule, which is only effective for\nhalf-metallic Heusler compounds, our machine-learning approach is more generic\nsince it applies to any Co$_2$YZ Heusler compounds, regardless of whether they\nare half-metals or not. We use this new rule to estimate the magnetic moments\nof a few yet-to-be-discovered Heusler compounds and compare the results to\ndensity functional theory (DFT) based calculations. Finally, we use DFT and\nmachine learning investigations to prove their stability.",
        "positive": "Quantification of the spin-Hall anti-damping torque with a resonance\n  spectrometer: We present a simple technique using a cavity-based resonance spectrometer to\nquantify the anti-damping torque due to the spin Hall effect. Modification of\nferromagnetic resonance is observed as a function of small DC current in\nsub-mm-wide strips of bilayers, consisting of magnetically soft FeGaB and\nstrong spin-Hall metal Ta. From the detected current-induced linewidth change,\nwe obtain an effective spin Hall angle of 0.08-0.09 independent of the magnetic\nlayer thickness. Our results demonstrate that a sensitive resonance\nspectrometer can be a general tool to investigate spin Hall effects in various\nmaterial systems, even those with vanishingly low conductivity and\nmagnetoresistance."
    },
    {
        "anchor": "Broadband dielectric spectroscopy of Ba(Zr,Ti)O3: dynamics of relaxors\n  and diffuse ferroelectrics: Broadband dielectric spectroscopy from Hz up to the infrared (IR) range and\ntemperature interval 10-300 K was carried out for xBaZrO3-(1-x)BaTiO3 (BZT-x, x\n= 0.6, 0.7, 0.8) solid solution ceramics and compared with similar studies for\nx = 0, 0.2, 0.4, 1 ceramics published recently (Phys. Rev. B 86, 014106\n(2012)). Rather complex IR spectra without appreciable mode softening are\nascribed to Last-Slater transverse optic (TO) phonon eigenvector mixing and\npossible two-mode mixed crystal behavior. Fitting of the complete spectral\nrange requires a relaxation in the 100 GHz range for all the samples. Below 1\nGHz another relaxation appears, which is thermally activated and obeys the same\nArrhenius behavior for all the relaxor BZT samples. The frequently reported\nVogel-Fulcher behavior in BZT relaxors is shown to be an artifact of the\nevaluation from the permittivity or loss vs. temperature dependences instead of\nits evaluation from loss vs. frequency maxima. The relaxation is assigned to\nlocal hopping of the off-centered Ti4+ ions in the frozen BTO clusters, whose\nsize is rather small and cannot grow on cooling. Therefore BZT is to be\nconsidered as a dipolar glass rather than relaxor ferroelectric.",
        "positive": "Modeling of torsion stress giant magnetoimpedance in amorphous wires\n  with negative magnetostriction: A model describing the influence of torsion stress on the giant\nmagnetoimpedance in amorphous wires with negative magnetostriction is proposed.\nThe wire impedance is found by means of the solution of Maxwell equations\ntogether with the Landau-Lifshitz equation, assuming a simplified spatial\ndistribution of the magnetoelastic anisotropy induced by the torsion stress.\nThe impedance is analyzed as a function of the external magnetic field, torsion\nstress and frequency. It is shown that the magnetoimpedance ratio torsion\ndependence has an asymmetric shape, with a sharp peak at some value of the\ntorsion stress. The calculated field and stress dependences of the impedance\nare in qualitative agreement with results of the experimental study of the\ntorsion stress giant magnetoimpedance in Co-based amorphous wires."
    },
    {
        "anchor": "The sintering behavior of close packed spheres: The sintering behavior of close packed spheres is investigated using a\nnumerical model. The investigated systems are the body centered cubic (BCC),\nface centered cubic (FCC) and hexagonal closed packed spheres (HCP). The\nsintering behavior is found to be ideal with no grain growth until full density\nis reached for all systems. During sintering the grains change shape from\nspherical to tetrakaidecahedron, similar to the geometry analyzed by Coble (R.\nL. Coble, J. Appl. Phys. 32 (1961) 787).",
        "positive": "Quantum Monte Carlo Analysis of Exchange and Correlation in the Strongly\n  Inhomogeneous Electron Gas: We use variational quantum Monte Carlo to calculate the density-functional\nexchange-correlation hole n_{xc}, the exchange-correlation energy density\ne_{xc}, and the total exchange-correlation energy E_{xc}, of several electron\ngas systems in which strong density inhomogeneities are induced by a\ncosine-wave potential. We compare our results with the local density\napproximation and the generalized gradient approximation. It is found that the\nnonlocal contributions to e_{xc} contain an energetically significant\ncomponent, the magnitude, shape, and sign of which are controlled by the\nLaplacian of the electron density."
    },
    {
        "anchor": "Stability of Solid Electrolyte Interphase Components on Lithium Metal\n  and Reactive Anode Material Surfaces: Lithium ion batteries (LIB) can feature reactive anodes that operate at low\npotentials, such as lithium metal or silicon, passivated by solid electrolyte\ninterphase (SEI) films. SEI is known to evolve over time as cycling proceeds.\nIn this modeling work, we focus on the stability of two main SEI components,\nlithium carbonate (Li2CO3) and lithium ethylene dicarbonate (LEDC). Both\ncomponents are electrochemically stable but thermodynamically unstable near the\nequilibrium Li+/Li(s) potential. Interfacial reactions represent one way to\ntrigger the intrinsic thermodynamic instability. Both Li(2)CO(3) and LEDC are\npredicted to exhibit exothermic reactions on lithium metal surfaces, and the\nbarriers are sufficiently low to permit reactions on battery operation time\nscales. LEDC also readily decomposes on high Li-content Li(x)Si surfaces. Our\nstudies suggest that the innermost SEI layer on lithium metal surfaces should\nbe a thin layer of Li(2)O -- the only thermodynamically and kinetically stable\ncomponent (in the absence of a fluoride source). This work should also be\nrelevant to inadvertant lithium plating during battery cycling, and SEI\nevolution on Li(x)Si surfaces.",
        "positive": "Growth kinetics and atomistic mechanisms of native oxidation of\n  ZrS$_x$Se$_{2-x}$ and MoS$_2$ crystals: A thorough understanding of native oxides is essential for designing\nsemiconductor devices. Here we report a study of the rate and mechanisms of\nspontaneous oxidation of bulk single crystals of ZrS$_x$Se$_{2-x}$ alloys and\nMoS$_2$. ZrS$_x$Se$_{2-x}$ alloys oxidize rapidly, and the oxidation rate\nincreases with Se content. Oxidation of basal surfaces is initiated by\nfavorable O$_2$ adsorption and proceeds by a mechanism of Zr-O bond switching,\nthat collapses the van der Waals gaps, and is facilitated by progressive redox\ntransitions of the chalcogen. The rate-limiting process is the formation and\nout-diffusion of SO$_2$. In contrast, MoS$_2$ basal surfaces are stable due to\nunfavorable oxygen adsorption. Our results provide insight and quantitative\nguidance for designing and processing semiconductor devices based on\nZrS$_x$Se$_{2-x}$ and MoS$_2$, and identify the atomistic-scale mechanisms of\nbonding and phase transformations in layered materials with competing anions."
    },
    {
        "anchor": "Reversible attachment of platinum alloy nanoparticles to\n  non-functionalized carbon nanotubes: The formation of monodisperse, tunable sized, alloyed nanoparticles of Ni,\nCo, or Fe with Pt and pure Pt nanoparticles attached to carbon nanotubes has\nbeen investigated. Following homogeneous nucleation, nanoparticles attach\ndirectly to non-functionalized singlewall and multiwall carbon nanotubes during\nnanoparticle synthesis as a function of ligand nature and the nanoparticle work\nfunction. These ligands do not only provide a way to tune the chemical\ncomposition, size and shape of the nanoparticles but also control a strong\nreversible interaction with carbon nanotubes and permit controlling the\nnanoparticle coverage. Raman spectroscopy reveals that the sp2 hybridization of\nthe carbon lattice is not modified by the attachment. In order to better\nunderstand the interaction between the directly attached nanoparticles and the\nnon-functionalized carbon nanotubes we employed first-principles calculations\non model systems of small Pt clusters and both zig-zag and armchair singlewall\ncarbon nanotubes. The detailed comprehension of such systems is of major\nimportance since they find applications in catalysis and energy storage.",
        "positive": "Some peculiarities of water freezing at small sub-zero temperatures: I consider the kinetics of water freezing and show that, at small sub-zero\ntemperatures, (i) the time of ice nucleation within the bulk water environment\nis enormous and therefore cannot take place either in lakes of in living cells;\n(ii) that the ice nucleation needs some ice-binding surfaces to occur, but\n(iii) even this kind of ice nucleation can take place, as a rule, only at the\ntemperatures that are a few degrees below 0oC. Further, I discuss factors that\ncan drastically reduce the ice nucleation time at nearly-zero temperatures both\nin open reservoirs, where water contacts with air, and in cells, where there is\nno such contact."
    },
    {
        "anchor": "Unstable dynamics of model vicinal crystal surfaces: Initial and\n  intermediate stages: We approach the old-standing problem of vicinal crystal surfaces destabilized\nby step-down and step step-up currents from a unified modelling viewpoint with\nfocus on both the initial and the intermediate stages of the instability. We\ndevelop further our atomistic scale model of vicinal crystal growth (Gr)\ndestabilized by SD drift of the adatoms in order to account for also the\nvicinal crystal sublimation (Sbl) and the SU drift of the adatoms as an\nalternative mode of destabilization. In order to study the emergence of the\ninstability we use the number of steps in the bunch (bunch size) N as a measure\nand probe with small-size systems the models stability against step bunching\n(SB) on a dense grid of points in the parameter space formed by the diffusion\nrate/step transparency, surface miscut and drift direction, for each of the\nfour possible cases - Gr+SD, Gr+SU, Sbl+SD, Sbl+SU. The obtained stability\ndiagrams show where the system is initially most unstable and provide a ground\nto study there the intermediate stages of the developed instability quantifying\nthe surface self-similarity by the time-scaling of N. For each of the four\nenumerated cases we show that it reaches the universal curve N=2sqrt(T/3),\nwhere T is the time, properly rescaled with the model parameters. We confirm\nthe value of the numerical pre-factor with results from a parallel study of\nmodels based on systems of ordinary differential equations (ODE) for the step\nvelocity.",
        "positive": "Synthesis and characterization of FePt/Au core-shell nanoparticles: In this work, the structural and magnetic properties of the gold-coated FePt\nnanoparticles synthesized from high-temperature solution phase are presented.\nThe amount of gold was optimized to obtain most of the FePt particles coated.\nThe particle diameter increases from 4 to 10 nm as observed by TEM. The\nmagnetic properties are largely affected by the coating. At low temperature,\nthe coercive field Hc of the coated nanoparticles decreases about three times\nrespect to the uncoated and the blocking temperature reduces to the half. The\nchanges of the magnetic behavior are discussed in terms of the effect of the\ngold atoms at the FePt core surface."
    },
    {
        "anchor": "Data-driven discovery of novel 2D materials by deep generative models: Efficient algorithms to generate candidate crystal structures with good\nstability properties can play a key role in data-driven materials discovery.\nHere we show that a crystal diffusion variational autoencoder (CDVAE) is\ncapable of generating two-dimensional (2D) materials of high chemical and\nstructural diversity and formation energies mirroring the training structures.\nSpecifically, we train the CDVAE on 2615 2D materials with energy above the\nconvex hull $\\Delta H_{\\mathrm{hull}}< 0.3$ eV/atom, and generate 5003\nmaterials that we relax using density functional theory (DFT). We also generate\n14192 new crystals by systematic element substitution of the training\nstructures. We find that the generative model and lattice decoration approach\nare complementary and yield materials with similar stability properties but\nvery different crystal structures and chemical compositions. In total we find\n11630 predicted new 2D materials, where 8599 of these have $\\Delta\nH_{\\mathrm{hull}}< 0.3$ eV/atom as the seed structures, while 2004 are within\n50 meV of the convex hull and could potentially be synthesized. The relaxed\natomic structures of all the materials are available in the open Computational\n2D Materials Database (C2DB). Our work establishes the CDVAE as an efficient\nand reliable crystal generation machine, and significantly expands the space of\n2D materials.",
        "positive": "Synthesis of endohedral iron-fullerenes by ion implantation: In this paper, we discuss the results of our study of the synthesis of\nendohedral iron-fullerenes. A low energy Fe+ ion beam was irradiated to C60\nthin film by using a deceleration system. Fe+-irradiated C60 thin film was\nanalyzed by high performance liquid chromatography and laser\ndesorption/ionization time-of-flight mass spectrometry. We investigated the\nperformance of the deceleration system for using a Fe+ beam with low energy. In\naddition, we attempted to isolate the synthesized material from a\nFe+-irradiated C60 thin film by high performance liquid chromatography."
    },
    {
        "anchor": "A wave function based ab initio non-equilibrium Green's function\n  approach to charge transport: We present a novel ab initio non-equilibrium approach to calculate the\ncurrent across a molecular junction. The method rests on a wave function based\ndescription of the central region of the junction combined with a tight binding\napproximation for the electrodes in the frame of the Keldysh Green's function\nformalism. In addition we present an extension so as to include effects of the\ntwo-particle propagator. Our procedure is demonstrated for a dithiolbenzene\nmolecule between silver electrodes. The full current-voltage characteristic is\ncalculated. Specific conclusions for the contribution of correlation and\ntwo-particle effects are derived. The latter are found to contribute about 5%\nto the current. The order of magnitude of the current coincides with\nexperiments.",
        "positive": "Atomistic manipulation of reversible oxidation and reduction in Ag by\n  electron beam: Employing electrons for direct control of nanoscale reaction is highly\ndesirable since it provides fabrication of nanostructures with different\nproperties at atomic resolution and with flexibility of dimension and location.\nHere, applying in situ transmission electron microscopy, we show the reversible\noxidation and reduction kinetics in Ag, well controlled by changing the dose\nrate of electron beam. Aberration-corrected high-resolution transmission\nelectron microscopy observation reveals that O atoms are preferably inserted\nand extracted along the {111} close-packed planes of Ag, leading to the\nnucleation and decomposition of nanoscale Ag2O islands on the Ag substrate. By\ncontrolling electron beam size and dose rate, we demonstrated fabrication of an\narray of 3 nm Ag2O nanodots in an Ag matrix. Our results open up a new pathway\nto manipulate atomistic reaction with electron beam towards the precise\nfabrication of nanostructures for device applications."
    },
    {
        "anchor": "Phase Transitions and Superconductivity in Ternary Hydride Li$_2$SiH$_6$\n  at High Pressures: We predicted a new ternary hydride Li$_2$SiH$_6$ at high pressures. A\nsystematic structure search in Li$_2$SiH$_6$ compound reveals novel stable\nphases with intriguing electronic and phonon properties. It is found that\nLi$_2$SiH$_6$ is dynamically stable from ambient pressure up to 400 GPa with\nthree novel phases: P312, P$\\bar{3}$, and P$\\bar{6}$2m. The calculation of\nelectron-phonon coupling combined with Bardeen-Cooper-Schrieffer's argument\nindicates that this compound may be a candidate for high $T_c$ superconductors\nunder high pressures. In particular, the maximum $T_c$ of\n$P\\bar{6}2m$-Li$_2$SiH$_6$ at 400 GPa reaches 56 K. These findings may pave the\nway for obtaining room temperature superconductors in dense hydrogen-rich\ncompounds.",
        "positive": "Coexistence of bunching and meandering instability in simulated growth\n  of 4H-SiC(0001) surface: Bunching and meandering instability of steps at the 4H-SiC(0001) surface is\nstudied by the kinetic Monte Carlo simulation method. Change in the character\nof step instability is analyzed for different rates of particle jumps towards\nstep. In the experiment effective value of jump rates can be controlled by\nimpurities or other growth conditions. An anisotropy of jump barriers at the\nstep influences the character of surface structure formed in the process of\ncrystal growth. Depending on the growth parameters different surface patterns\nare found. We show phase diagrams of surface patterns as a function of\ntemperature and crystal growth rate for two different choices of step kinetics\nanisotropy. Jump rates which effectively model high inverse Schwoebel barrier\n(ISB) at steps lead either to regular, four-multistep or bunched structure. For\nweak anisotropy at higher temperatures or for lower crystal growth rates\nmeanders and mounds are formed, but on coming towards lower temperatures and\nhigher rates we observe bunch and meander coexistence. These results show that\ninterplay between simple dynamical mechanisms induced by the asymmetry of the\nstep kinetics and step movement assisted by the step edge diffusion are\nresponsible for different types of surface morphology."
    },
    {
        "anchor": "Synthesis and characterization of PEG-coated\n  Zn$_{0.3}$Mn$_x$Fe$_{2.7-x}$O$_4$ nanoparticles as the dual T1/T2-weighted\n  MRI contrast agent: Super-paramagnetic nanoparticles (NPs) have been widely explored as magnetic\nresonance imaging (MRI) contrast agents because of a combination of favorable\nmagnetic properties, biocompability and ease of fabrication. MRI using\ntraditional T1- or T2-weighted single mode contrast-enhanced techniques may\nyield inaccurate imaging results. In the present work, a T1/T2 dual mode\ncontrast agent based on the super-paramagnetic zinc-manganese ferrite\n(Zn$_{0.3}$Mn$_x$Fe$_{2.7-x}$O$_4$, x= 0, 0.25, 0.75 and 1) NPs with small core\nsize and a hydrophilic PEG surface coating is reported. The TEM, TGA and FTIR\nresults confirmed the formation of a uniform coating on the NPs surface. The\nMRI analysis revealed that the Zn$_{0.3}$Mn$_{0.5}$Fe$_{2.2}$O$_4$ NPs had the\nmaximum image contrast compared to other zinc-manganese ferrite samples. Cell\nviability evaluations revealed that the coated and uncoated particles did not\ninhibit cell growth pattern. The present PEG-coated\nZn$_{0.3}$Mn$_{0.5}$Fe$_{2.2}$O$_4$ NPs can be utilized as a suitable\nT1/T2-weighted MRI contrast agent for better diagnostic of abnormalities in the\norgans or tissues.",
        "positive": "Purely orbital diamagnetic to paramagnetic fluctuation of quasi\n  two-dimensional carriers under in-plane magnetic field: An external magnetic field, $H$, applied parallel to a quasi two-dimensional\nsystem modifies quantitatively and qualitatively the density of states. Using a\nself-consistent numerical approach, we study how this affects the entropy, $S$,\nthe free energy, $F$, and the magnetization, $M$, for different sheet carrier\nconcentrations, $N_s$. As a prototype system we employ III-V double quantum\nwells. We find that although $M$ is mainly in the opposite direction of $H$,\nthe system is not linear. Surprisingly $\\partial M / \\partial H$ swings between\nnegative and positive values, i.e., we predict an entirely orbital diamagnetic\nto paramagnetic fluctuation. This phenomenon is important compared to the ideal\nde Haas-van Alphen effect i.e. the corresponding phenomenon under perpendicular\nmagnetic field."
    },
    {
        "anchor": "Magnetic damping modulation in $IrMn_{3}/Ni_{80}Fe_{20}$ via the\n  magnetic spin Hall effect: Non-collinear antiferromagnets can have additional spin Hall effects due to\nthe net chirality of their magnetic spin structure, which provides for more\ncomplex spin-transport phenomena compared to ordinary non-magnetic materials.\nHere we investigated how ferromagnetic resonance of permalloy\n($Ni_{80}Fe_{20}$) is modulated by spin Hall effects in adjacent epitaxial\n$IrMn_{3}$ films. We observe a large dc modulation of the ferromagnetic\nresonance linewidth for currents applied along the [001] $IrMn_{3}$ direction.\nThis very strong angular dependence of spin-orbit torques from dc currents\nthrough the bilayers can be explained by the magnetic spin Hall effect where\n$IrMn_{3}$ provides novel pathways for modulating magnetization dynamics\nelectrically.",
        "positive": "Equilibrium in solid-state electrochemical cells at sample-electrolyte\n  boundary: In solid-state electrochemical experiments, the boundary between the sample\nand the electrolyte plays a crucial role, and the rest of the sample acting as\na buffer that maintains a fixed composition. Due to the presence of an\nelectrochemical circuit in the cell (ionic conductivity in the electrolyte and\nelectronic conductivity in the sample system), the chemical potential is\nequalized at the electrolyte-sample boundary. This leads to an equilibrium\nstate and allows for the measurement of equilibrium values, regardless of the\nassumptions made by the experimenters. This article demonstrates the principle\nof equalizing the electrochemical potential at the electrolyte-sample\ninterface, which explains why achieving equilibrium in the presence of an\nelectrolyte can occur much faster compared to sample synthesis, which often\noccurs at higher temperatures. This fact can be used to synthesize sample\nsystems or other substances at the required temperatures with a significant\nreduction in synthesis time."
    },
    {
        "anchor": "Curvature dependent surface energy for free standing monolayer graphene:\n  geometrical and material linearization with closed form solutions: Continuum modeling of a free-standing graphene monolayer, viewed as a two\ndimensional 2-lattice, requires specifications of the components of the shift\nvector that act as an auxiliary variable. The field equations are then the\nequations ruling the shift vector, together with momentum and moment of\nmomentum equations. To introduce material linearity energy is assumed to have a\nquadratic dependence on the strain tensor, the curvature tensor, the shift\nvector, as well as to combinations of them. Hexagonal symmetry then reduces the\noverall number of independent material constants to nine. We present an\nanalysis of simple loading histories such as axial, biaxial tension/compression\nand simple shear for a range of problems of increasing difficulty for the\ngeometrically and materially linear case. We start with the problem of in-plane\nmotions only. By prescribing the displacement, the components of the shift\nvector are evaluated. This way the field equations are satisfied trivially.\nOut-of-plane motions are treated as well; we assume in-plane\ntension/compression that leads to buckling/wrinkling and solve for the\ncomponents of the shift vector as well as the function present in buckling's\nmodeling. The assumptions of linearity adopted here simplifies the analysis and\nfacilitates analytical results.",
        "positive": "Changes in magnetic scattering anisotropy at a\n  ferromagnetic/superconducting interface: We show that some metals and alloys (X = Cu, Ag, FeMn, or Cu and Ag combined\nwith each other), sputtered between ferromagnetic Co and superconducting Nb,\nproduce no change in current-perpendicular-to-plane magnetoresistance (CPP-MR)\nin a carefully designed CPP-spin-valve. In contrast, other metals (Ru or Au) or\ncombinations (Cu or Ag combined with Au, Ru, or FeMn) change the CPP-MR, in\nsome cases even reversing its sign. We ascribe these changes to activation of\nmagnetic scattering anisotropies at a ferromagnetic/superconducting interface,\napparently by strong spin-flipping between the Co and Nb layers."
    },
    {
        "anchor": "R2D2 -- An equivalent-circuit model that quantitatively describes domain\n  wall conductivity in ferroelectric LiNbO$_3$: Ferroelectric domain wall (DW) conductivity (DWC) can be attributed to two\nseparate mechanisms: (a) the injection/ejection of charge carriers across the\nSchottky barrier formed at the (metal-) electrode-DW junction and (b) the\ntransport of those charge carriers along the DW. Current-voltage (IU)\ncharacteristics, recorded at variable temperatures from LiNbO$_3$ (LNO) DWs,\nare clearly able to differentiate between these two contributions. Practically,\nthey allow us here to directly quantify the physical parameters relevant for\nthe two mechanisms (a) and (b) mentioned above. These are, e.g., the resistance\nof the DW, the saturation current, the ideality factor, and the Schottky\nbarrier height of the electrode/DW junction. Furthermore, the activation\nenergies needed to initiate the thermally-activated electronic transport along\nthe DWs, can be extracted. In addition, we show that electronic transport along\nLiNbO$_3$ DWs can be elegantly viewed and interpreted in an adapted\nsemiconductor picture based on a double-diode/double-resistor equivalent\ncircuit model, the R2D2 model. Finally, our R2D2 model was checked for its\nuniversality by fitting the DWC data not only to z-cut LNO bulk DWs, but\nequally to z-cut thin-film LNO DWs, and DWC from x-cut DWs as reported in\nliterature.",
        "positive": "Defect Imaging and Detection of Precipitates Using a New Scanning\n  Positron Microbeam: We report on a newly developed scanning positron microbeam based on threefold\nmoderation of positrons provided by the high intensity positron source NEPOMUC.\nFor brightness enhancement a remoderation unit with a $100\\,$nm thin Ni(100)\nfoil and 9.6% efficiency is applied to reduce the area of the beam spot by a\nfactor of 60. In this way, defect spectroscopy is enabled with a lateral\nresolution of $33\\,\\mu$m over a large scanning range of $19\\times19\\,$mm$^{2}$.\nMoreover, 2D defect imaging using Doppler broadening spectroscopy (DBS) is\ndemonstrated to be performed within exceptional short measurement times of less\nthan two minutes for an area of $1\\times1$mm$^{2}$ ($100\\times100\\,\\mu$m$^{2}$)\nwith a resolution of $250\\,\\mu$m ($50\\,\\mu$m). We studied the defect structure\nin laser beam welds of the high-strength agehardened Al alloy (AlCu6Mn, EN\nAW-2219 T87) by applying (coincident) DBS with unprecedented spatial\nresolution. The visualization of the defect distribution revealed a sharp\ntransition between the raw material and the welded zone as well as a very small\nheat affected zone. Vacancy-like defects and Cu rich precipitates are detected\nin the as-received material and, to a lesser extent, in the transition zone of\nthe weld. Most notably, in the center of the weld vacancies without forming\nCu-vacancy complexes, and the dissolution of the Cu atoms in the crystal\nlattice, i.e. formation of a supersaturated solution, could be clearly\nidentified."
    },
    {
        "anchor": "Atomic structure, electronic structure and optical absorption of\n  inorganic perovskite compounds Cs2SnI6-nXn (X=F, Cl, Br; n= 0~6): A\n  first-principles study: As a possible alternative to organic-inorganic hybrid perovskite halide,\ninorganic Cs2SnI6 has drawn more and more research attention recently. In order\nto find more Cs2SnI6 derivatives as the potential solar cell absorber\nmaterials, I- ions in Cs2SnI6 are replaced by other halogen ions and forms the\nCs2SnI6-nXn (X=F, Cl, Br; n=1~6) compounds, whose atomic structures, electronic\nstructures and optical absorption are investigated by first principles\ncalculation. When the alloying level n increases, the mean lattice constants,\nthe weighted Sn-X and Cs-X bond lengths all decreases linearly; the bond length\nof each Sn-X diminishes slightly inside the octahedral structure; Eg of\nCs2SnI6-nXn increases nonlinearly. Eleven Cs2SnI6-nXn compounds have an Eg\nbetween 1.0 eV and 2.0 eV and so can be potentially used as the light\nabsorption layer of solar cells. Their partial DOS demonstrate that as the\nalloying level n increases, I 5p orbital in VBM and CBM is gradually\nsubstituted by Br 4p, or Cl 3p, or F 2p orbital. The eleven Cs2SnI6-nXn alloys\nall have a direct bandgap although the lattice distortion induced by the\nalloyed X- ion.",
        "positive": "First-principles quantitative prediction of the lattice thermal\n  conductivity in random semiconductor alloys: the role of force-constant\n  disorder: The standard theoretical understanding of the lattice thermal conductivity,\n$\\kappa_{\\ell}$, of semiconductor alloys assumes that mass disorder is the most\nimportant source of phonon scattering. In contrast, we show that the hitherto\nneglected contribution of force-constant (IFC) disorder is essential to\naccurately predict the $\\kappa_{\\ell}$ of those polar compounds characterized\nby a complex atomic-scale structure. We have developed an \\emph{ab initio}\nmethod based on special quasirandom structures and Green's functions, and\nincluding the role of IFC disorder, and applied it in order to calculate the\n$\\kappa_{\\ell}$ of $\\mathrm{In_{1-x}Ga_xAs}$ and $\\mathrm{Si_{1-x}Ge_x}$\nalloys. We show that, while for $\\mathrm{Si_{1-x}Ge_x}$, phonon-alloy\nscattering is dominated by mass disorder, for $\\mathrm{In_{1-x}Ga_xAs}$, the\ninclusion of IFC disorder is fundamental to accurately reproduce the\nexperimentally observed $\\kappa_{\\ell}$. As the presence of a complex\natomic-scale structure is common to most III-V and II-VI random semiconductor\nalloys, we expect our method to be suitable for a wide class of materials."
    },
    {
        "anchor": "First-principles effective-mass Hamiltonian for semiconductor\n  nanostructures in a magnetic field: A multi-band effective-mass Hamiltonian is derived for lattice-matched\nsemiconductor nanostructures in a slowly varying external magnetic field. The\ntheory is derived from the first-principles magnetic-field coupling Hamiltonian\nof Pickard and Mauri, which is applicable to nonlocal norm-conserving\npseudopotentials in the local density approximation to density functional\ntheory. The pseudopotential of the nanostructure is treated as a perturbation\nof a bulk reference crystal, with linear and quadratic response terms included\nin k.p perturbation theory. The resulting Hamiltonian contains several\ninterface terms that have not been included in previous work on nanostructures\nin a magnetic field. The derivation provides the first direct analytical\nexpressions showing how the coupling of the nonlocal potential to the magnetic\nfield influences the effective magnetic dipole moment of the electron.",
        "positive": "Metastable defect phase diagrams as a tool to describe chemically driven\n  defect formation: Application to planar defects: Thermodynamic bulk phase diagrams have become the roadmap used by researchers\nto identify alloy compositions and process conditions that result in novel\nmaterials with tailored microstructures. Recent experimental studies show that\nchanges in the alloy composition can drive not only transitions in the bulk\nphases present in a material, but also in the concentration and type of defects\nthey contain. Defect phase diagrams in combination with density functional\ntheory provide a natural route to study these chemically driven defects. Our\nresults show, however, that direct application of thermodynamic approaches can\nfail to reproduce the experimentally observed defect formation. Therefore, we\nextend the concept to metastable defect phase diagrams to account for kinetic\nlimitations that prevent the system from reaching equilibrium. We successfully\napplied this concept to explain the formation of large concentrations of planar\ndefects in supersaturated Fe-Nb solid solutions and to identify in a joint\nstudy with experiments conditions in Mg-Al-Ca alloys for defect phase\noccurrence. The concept offers new avenues for designing materials with\ntailored defect structures."
    },
    {
        "anchor": "Polarization dependent femtosecond laser modification of MBE-grown III-V\n  nanostructures on silicon: We report a novel, polarization dependent, femtosecond laser-induced\nmodification of surface nanostructures of indium, gallium, and arsenic grown on\nsilicon via molecular beam epitaxy, yielding shape control from linear and\ncircular polarization of laser excitation. Linear polarization causes an\nelongation effect, beyond the dimensions of the unexposed nanostructures,\nranging from 88 nm to over 1 um, and circular polarization causes the\nnanostructures to flatten out or form loops of material, to diameters of\napproximately 195 nm. During excitation, it is also observed that the generated\nsecond and third harmonic signals from the substrate and surface nanostructures\nincrease with exposure time.",
        "positive": "Calculated Effects of Vacancy and Ti-doping in 2D Janus MoSSe for\n  Photocatalysis: Two-dimensional (2D) Janus transitional metal dichalcogenides (TMDCs) have\ngreat potential for photocatalytic water splitting due to their novel\nproperties induced by the unique out-of-plane asymmetric structures. Here, we\nsystematically investigate the geometric, electronic and optical properties of\n2D Janus MoSSe with titanium doping and vacancies to explore their synergistic\neffects on photocatalytic activity. We find that there are effective\nattractions between the substituted or adsorbed Ti atoms and S/Se vacancies.\nThe Ti adatoms dramatically extend the light absorption range to infrared\nregion. The S/Se vacancies coexisting with Ti adatoms will modulate the\ntransition of photo-excited electrons, thereby enhancing the sunlight\nabsorption. The Ti adatoms either existing alone or coexisting with vacancies\nintroduce smaller lattice distortion compared to substituted Ti atoms and these\nTi adatoms induce smaller effective mass of charge carriers. The configuration\nof S vacancy coexisting with Ti adatoms on Se-surface exhibits the most\nsignificant synergistic effects and best overall photocatalytic performance.\nOur work reveals the mechanism and effects induced by doping and vacancies\ncoexisting in 2D Janus TMDCs, also propose a new practical strategy to improve\nthe performance of 2D photocatalysts."
    },
    {
        "anchor": "First Observed Metal-like to Insulator Transition in the vacant 3d\n  orbital Quantum Spin Liquid Tb$_2$Ti$_2$O$_7$: We report the observation of metal-like to insulator transition (MTI) in the\n3dpyrochlore oxide Tb2Ti2O7 at 603 K due to the interaction of empty 3d\norbitals of Ti4+ with O2- ions, evidenced by the transition in resistivity.\nMagnetisation, specific heat capacity and differential scanning calorimetry\nsupport the MTI, and the transition is of second order. An appreciable change\nin magnetisation with temperature, without any magnetic phase transition, is a\nbehaviour typical in this family of compounds which is seldom observed in empty\nd orbital pyrochlores. The possible mechanism that supports the MTI in Tb2Ti2O7\nis discussed. Subsequently, a broad change in magnetisation from 696 K is also\nseen. Thermogravimetric analysis confirms the observed MTI (603 K) and the\nbroad change in magnetisation (696 K)are not due to oxygen vacancy",
        "positive": "Separating Inverse spin Hall voltage and spin rectification voltage by\n  inverting spin injection direction: We develop a method for universally resolving the important issue of\nseparating the inverse spin Hall effect (ISHE) from spin rectification effect\n(SRE) signal. This method is based on the consideration that the two effects\ndepend on the spin injection direction: The ISHE is an odd function of the spin\ninjection direction while the SRE is independent on it. Thus, inversion of the\nspin injection direction changes the ISHE voltage signal, while SRE voltage\nremains. It applies generally to analyzing the different voltage contributions\nwithout fitting them to special line shapes. This fast and simple method can be\nused in a wide frequency range, and has the flexibility of sample preparation."
    },
    {
        "anchor": "Measurement of the Spin-Forbidden Dark Excitons in MoS2 and MoSe2\n  monolayers: Excitons with binding energies of a few hundreds of meV control the optical\nproperties of transition metal dichalcogenide monolayers. Knowledge of the fine\nstructure of these excitons is therefore essential to understand the\noptoelectronic properties of these 2D materials. Here we measure the exciton\nfine structure of MoS2 and MoSe2 monolayers encapsulated in boron nitride by\nmagneto-photoluminescence spectroscopy in magnetic fields up to 30 T. The\nexperiments performed in transverse magnetic field reveal a brightening of the\nspin-forbidden dark excitons in MoS2 monolayer: we find that the dark excitons\nappear at 14 meV below the bright ones. Measurements performed in tilted\nmagnetic field provide a conceivable description of the neutral exciton fine\nstructure. The experimental results are in agreement with a model taking into\naccount the effect of the exchange interaction on both the bright and dark\nexciton states as well as the interaction with the magnetic field.",
        "positive": "First Principles Modeling of the Temperature Dependent Ternary Phase\n  Diagram for the Cu-Pd-S System: As an aid to the development of hydrogen separation membranes, we predict the\ntemperature dependent phase diagrams using first principles calculations\ncombined with thermodynamic principles. Our method models the phase diagram\nwithout empirical fitting parameters. By applying thermodynamic principles and\nsolid solution models, temperature-dependent features of the Cu-Pd-S system can\nbe explained, specifically solubility ranges for substitutions in select\ncrystalline phases. Electronic densities of states calculations explain the\nrelative favorability of certain chemical substitutions. In addition, we\ncalculate sulfidization thresholds for the Pd-S2 system and activities for the\nCu-Pd binary in temperature regimes where the phase diagram contains multiple\nsolid phases."
    },
    {
        "anchor": "On the hyperfine interaction in rare-earth Van Vleck paramagnets at high\n  magnetic fields: An influence of high magnetic fields on hyperfine interaction in the\nrare-earth ions with non-magnetic ground state (Van Vleck ions) is\ntheoretically investigated for the case of $Tm^{3+}$ ion in axial symmetrical\ncrystal electric field (ethylsulphate crystal). It is shown that magnetic-field\ninduced distortions of $4f$-electron shell lead to essential changes in\nhyperfine magnetic field at the nucleus. The proposed theoretical model is in\nagreement with recent experimental data.",
        "positive": "Extending phase field models of grain boundaries to three dimensions: In this letter we describe a method of extending an existing phase field\nmodel of polycrystalline solidification from two to three dimensions (3D)."
    },
    {
        "anchor": "Extra electron reflections in concentrated alloys do not necessitate\n  short-range order: In many concentrated alloys of current interest, the observation of diffuse\nsuperlattice intensities by transmission electron microscopy has been\nattributed to chemical short-range order. We briefly review these findings and\ncomment on the plausibility of widespread interpretations, noting the absence\nof expected peaks, conflicts with theoretical predictions, and the possibility\nof alternative explanations.",
        "positive": "Structural and Electronic Properties of Defective AlN/GaN Hybrid\n  Nanostrutures: Due to the wide range of possible applications, atomically thin\ntwo-dimensional heterostructures have attracted much attention. In this work,\nusing first-principles calculations, we investigated the structural and\nelectronic properties of planar AlN/GaN hybrid heterojunctions with the\npresence of vacancies at their interfaces. Our results reveal that a single\nvacant site, produced by the removal of Aluminum or Gallium atom, produces\nsimilar electronic band structures with localized states within the bandgap. We\nhave also observed a robust magnetic behavior. A nitrogen-vacancy, on the other\nhand, induces the formation of midgap states with reduced overall\nmagnetization. We have also investigated nanotubes formed by rolling up these\nheterojunctions. We observed that tube curvature does not substantially affect\nthe electronic and magnetic properties of their parent AlN/GaN heterojunctions.\nFor armchair-like tubes, a transition from direct to indirect bandgap was\nobserved as a consequence of changing the system geometry from 2D towards a\nquasi-one-dimensional one. The magnetic features presented by the AlN/GaN\ndefective lattices make them good candidates for developing new spintronic\ntechnologies."
    },
    {
        "anchor": "High-pressure structural study of the scheelite tungstates CaWO4 and\n  SrWO4: Angle-dispersive x-ray diffraction (ADXRD) and x-ray absorption near edge\nstructure (XANES) measurements have been performed in the AWO4 tungstates CaWO4\nand SrWO4 under high pressure up to approximately 20 GPa. Similar phase\ntransitions and phase transition pressures have been observed for both\ntungstates using the two techniques in the studied pressure range. Both\nmaterials are found to undergo a pressure-induced scheelite-to-fergusonite\nphase transition under sufficiently hydrostatic conditions. Our results are\ncompared to those found previously in the literature and supported by ab initio\ntotal energy calculations. From the total energy calculations we have also\npredicted a second phase transition from the fergusonite structure to a new\nstructure identified as Cmca. Finally, a linear relationship between the charge\ndensity in the AO8 polyhedra of ABO4 scheelite-related structures and the bulk\nmodulus is discussed and used to predict the bulk modulus of other materials,\nlike zircon.",
        "positive": "Comparative study of electronic and magnetic properties of $M$Pc ($M$ =\n  Fe, Co) molecules physisorbed on 2D MoS$_2$ and graphene: In this paper, we have done a comparative study of electronic and magnetic\nproperties of iron phthalocyanine (FePc) and cobalt phthalocyanine (CoPc)\nmolecules physisorbed on monolayer of MoS$_2$ and graphene by using density\nfunctional theory. Various different types of physisorption sites have been\nconsidered for both surfaces. Our calculations reveal that the $M$Pc molecules\nprefer the S-top position on MoS$_2$. However, on graphene, FePc molecule\nprefers the bridge position while CoPc molecule prefers the top position. The\n$M$Pc molecules are physisorbed strongly on the MoS$_2$ surface than the\ngraphene ($\\sim$ 2.5 eV higher physisorption energy). Analysis of magnetic\nproperties indicates the presence of strong spin dipole moment opposite to the\nspin moment and hence a huge reduction of effective spin moment can be\nobserved. Our calculations of magnetic anisotropy energies using both\nvariational approach and $2^{nd}$ order perturbation approach indicate no\nsignificant changes after physisorption. In case of FePc, an out-of-plane easy\naxis and in case of CoPc, an in-plane easy axis can be seen. Calculations of\nwork function indicate a reduction of MoS$_2$ work function $\\sim$ 1 eV due to\nphysisorption of $M$Pc molecules while it does not change significantly in case\nof graphene."
    },
    {
        "anchor": "Optical properties of an interacting large polaron gas: The normal state conductivity of a system of interacting large polarons is\ncalculated within the Random Phase approximation and some numerical results are\npresented. The behaviour of the optical absorption as a function of the charge\ncarrier density and of the temperature is analyzed for different values of the\nelectron-phonon coupling constant. It is shown that the conductivity exihibits\nfeatures similar to thos observed in the infrared spectra of the cuprates.",
        "positive": "Grain Growth and the Effect of Different Time Scales: Many technologically useful materials are polycrystals composed of a myriad\nof small monocrystalline grains separated by grain boundaries. Dynamics of\ngrain boundaries play a crucial role in determining the grain structure and\ndefining the materials properties across multiple scales. In this work, we\nconsider two models for the motion of grain boundaries with the dynamic lattice\nmisorientations and the triple junctions drag, and we conduct extensive\nnumerical study of the models, as well as present relevant experimental results\nof grain growth in thin films."
    },
    {
        "anchor": "Formation and characterization of an Al-rich metastable phase in Al-B\n  phase diagram: Vacuum heat treatment of mechanically-alloyed powders of boron and aluminum\nleads to formation of a metastable Al-rich phase, which can be quenched. Its\nstructure, composition, and thermal stability are established. With chemical\nformula Al1.28B the rhombohedral phase is unusually rich in Al. Parameters of\nthe unit cell determined from X-ray powder diffraction are: a=18.3464(19)\n{\\AA}, c=8.9241(9) {\\AA}, 2601.3(6) {\\AA}3, space group R-3. It is stable at\nheating up to 630 {\\deg}C. It is suggested that this phase is an important\nintermediate step in formation of AlB2 and, eventually, of other borides and\nits nucleation and thermal stability are explained by high elastic energy\nhindering formation of equilibrium phases at low temperatures.",
        "positive": "Oxygen Evolution Reaction on Perovskites: A Multieffect Descriptor Study\n  Combining Experimental and Theoretical Methods: The correlation between ex situ electronic conductivity, oxygen vacancy\ncontent, flat-band potential (Efb), and the oxygen evolution reaction (OER)\nactivity for a wide range of perovskite compositions are investigated\nexperimentally and theoretically. It is found that all of these parameters can\naffect the OER activity; however, none of them alone play a crucial role in\ndetermining the electrocatalytic activity. The correlation of one single\nphysicochemical property with the OER activity always presents deviation\npoints, indicating that a limitation does exist for such 2-dimensional\ncorrelations. Nevertheless, these deviations can be explained considering other\nphysicochemical properties and their correlation with the OER activity. Hence,\nthis work aims in simultaneously linking the OER activity with several\nphysicochemical materials properties. The concept of the OER/multidescriptor\nrelationship represents a significant advancement in the search and design of\nhighly active oxygen evolution catalysts, in the quest for efficient anodes in\nwater electrolyzers."
    },
    {
        "anchor": "Structure and Magnetism of HoBaCo2O5+delta Layered Cobaltites with\n  0.02<delta<0.22: In this paper we have studied, by means of high-resolution neutron powder\ndiffraction and magnetic susceptibility, the structural and magnetic features\nof selected samples of the HoBaCo2O5+delta layered cobaltite in the low oxygen\ncontent range (0.02<delta<0.22). The results shows a strong antiferromagnetic\ncontribution at room temperature coupled to an intermediate spin state of the\nCo3+ ions.",
        "positive": "Transition metal doped ZnS monolayer: The first principles insights: Structural and electronic properties of pristine and transition metal doped\nZnS monolayer are investigated within the framework of density functional\ntheory. The pristine ZnS monolayer is showing direct band gap of about 2.8 eV.\nThe investigated transition metal doping showed the transition from\nnon-magnetic semiconductor to a magnetic system e.g. magnetic semiconductor for\nCo doped ZnS and half metal for Ni doped ZnS monolayers. The Co doped ZnS\nmonolayer showed higher formation energy, confirming the strong bonding than\nthat of Ni doped ZnS monolayer. The electron difference density shows the\ncharge sharing between transition metal (Ni and Co) and S, confirming the\ncovalent bond formation."
    },
    {
        "anchor": "Interfacial adhesion between graphene and silicon dioxide by density\n  functional theory with van der Waals corrections: Interfacial adhesion between graphene and a SiO2 substrate is studied by\ndensity functional theory (DFT) with dispersion corrections. The results\ndemonstrate the van der Waals (vdW) interaction as the predominate mechanism\nfor the graphene/SiO2 interface. It is found that the interaction strength is\nstrongly influenced by changes of the SiO2 surface structures due to surface\nreactions with water. The adhesion energy is reduced when the reconstructed\nSiO2 surface is hydroxylated, and further reduced when covered by a monolayer\nof adsorbed water molecules. Thus, the effect of humidity may help explain the\nwide variation of adhesion energies measured in recent experiments between\ngraphene and SiO2. Moreover, it is noted that vdW forces are required to\naccurately model the graphene/SiO2 interface with DFT and that the adhesion\nenergy is underestimated by empirical force fields commonly used in atomistic\nsimulations.",
        "positive": "Dirac Fermions in Antiferromagnetic Semimetal: The analogues of elementary particles have been extensively searched for in\ncondensed matter systems because of both scientific interests and technological\napplications. Recently massless Dirac fermions were found to emerge as low\nenergy excitations in the materials named Dirac semimetals. All the currently\nknown Dirac semimetals are nonmagnetic with both time-reversal symmetry\n$\\mathcal{T}$ and inversion symmetry $\\mathcal{P}$. Here we show that Dirac\nfermions can exist in one type of antiferromagnetic systems, where\n$\\mathcal{T}$ and $\\mathcal{P}$ are broken but their combination $\\mathcal{PT}$\nis respected. We propose orthorhombic antiferromagnet CuMnAs as a candidate,\nanalyze the robustness of the Dirac points with symmetry protections, and\ndemonstrate its distinctive bulk dispersions as well as the corresponding\nsurface states by \\emph{ab initio} calculations. Our results give a new route\ntowards the realization of Dirac materials, and provide a possible platform to\nstudy the interplay of Dirac fermion physics and magnetism."
    },
    {
        "anchor": "Patterning of superconducting two-dimensional electron gases based on\n  AlO$_x$/KTaO$_3$(111) interfaces: The versatility of properties displayed by two-dimensional electron gases\n(2DEGs) at oxide interfaces has fostered intense research in hope of achieving\nexotic electromagnetic effects in confined systems. Of particular interest is\nthe recently discovered superconducting state appearing in (111)-oriented\nKTaO$_3$ interfaces, with a critical temperature $T_c \\approx 2$ K, almost ten\ntimes higher than that of SrTiO$_3$-based 2DEGs. Just as in SrTiO$_3$-based\n2DEGs, fabricating devices in this new system is a technical challenge due to\nthe fragility of the 2DEG and the propensity of bulk KTaO$_3$ to become\nconducting outside the devices upon adventitious oxygen vacancy doping. Here,\nwe present three different techniques for patterning Hall bars in\nAlO$_x$/KTaO$_3$~(111) heterostructures. The devices show superconducting\ntransitions ranging from 1.3 K to 1.78 K, with limited degradation from the\nunpatterned thin film, and enable an efficient tuning of the carrier density by\nelectric field effect. The array of techniques allows for the definition of\nchannels with a large range of dimensions for the design of various kinds of\ndevices to explore the properties of this system down to the nanoscale.",
        "positive": "Anomalous Thermal Transport of SrTiO$_3$ Driven by Anharmonic Phonon\n  Renormalization: SrTiO$_3$ has been extensively investigated owing to its abundant degrees of\nfreedom for modulation. However, the microscopic mechanism of thermal transport\nespecially the relationship between phonon scattering and lattice distortion\nduring the phase transition are missing and unclear. Based on deep-potential\nmolecular dynamics and self-consistent \\textit{ab initio} lattice dynamics, we\nexplore the lattice anharmonicity-induced tetragonal-to-cubic phase transition\nand explain this anomalous behavior during the phase transition. Our results\nindicate the significant role of the renormalization of third-order interatomic\nforce constants to second-order terms. Our work provides a robust framework for\nevaluating the thermal transport properties during structural transformation,\nbenefitting the future design of promising thermal and phononic materials and\ndevices."
    },
    {
        "anchor": "Quantum-Many-Body Intermetallics: Phase Stability of Fe$_3$Al and\n  Small-Gap Formation in Fe$_2$VAl: Various intermetallic compounds harbor subtle electronic correlation effects.\nTo elucidate this fact for the Fe-Al system, we perform a realistic many-body\ninvestigation based on the combination of density functional theory with\ndynamical mean-field theory in a charge self-consistent manner. A better\ncharacterization and understanding of the phase stability of bcc-based\nD0$_3$-Fe$_3$Al through an improved description of the correlated charge\ndensity and the magnetic-energy is achevied. Upon replacement of one Fe\nsublattice by V, the Heusler compound Fe$_2$VAl is realized, known to display\nbad-metal behavior and increased specific heat. We here document a charge-gap\nopening at low temperatures in line with previous experimental work. The gap\nstructure does not match conventional band theory and is reminiscent of\n(pseudo)gap charateristics in correlated oxides.",
        "positive": "Ballistic emission spectroscopy and imaging of a buried metal-organic\n  interface: The silver-p-phenylene (Ag-PPP) interface is investigated using ballistic\nelectron emission microscopy (BEEM). Multiple injection barriers and spatial\nnonuniformity of carrier injection over nanometer length scales are observed.\nNo unique injection barrier is found. Physical reasons for these features are\ndiscussed. BEEM current images and the surface topography of the silver film\nare uncorrelated."
    },
    {
        "anchor": "A Roadmap for Controlled and Efficient n-type Doping of Self-assisted\n  GaAs Nanowires Grown by Molecular Beam Epitaxy: N-type doping of GaAs nanowires has proven to be difficult because the\namphoteric character of silicon impurities is enhanced by the nanowire growth\nmechanism and growth conditions. The controllable growth of n-type GaAs\nnanowires with carrier density as high as 1020 electron/cm3 by self-assisted\nmolecular beam epitaxy using Te donors is demonstrated here. Carrier density\nand electron mobility of highly doped nanowires are extracted through a\ncombination of transport measurement and Kelvin probe force microscopy analysis\nin single-wire field-effect devices. Low-temperature photoluminescence is used\nto characterize the Te-doped nanowires over several orders of magnitude of the\nimpurity concentration. The combined use of those techniques allows the precise\ndefinition of the growth conditions required for effective Te incorporation.",
        "positive": "Graphene on h-BN: to align or not to align?: The contact strength, adhesion and friction, between graphene and an\nincommensurate crystalline substrate such as {\\it h}-BN depends on their\nrelative alignment angle $\\theta$. The well established Novaco-McTague (NM)\ntheory predicts for a monolayer graphene on a hard bulk {\\it h}-BN crystal face\na small spontaneous misalignment, here $\\theta_{NM}$\\,$\\simeq$\\,0.45 degrees\nwhich if realized would be relevant to a host of electronic properties besides\nthe mechanical ones. Because experimental equilibrium is hard to achieve, we\ninquire theoretically about alignment or misalignment by simulations based on\ndependable state-of-the-art interatomic force fields. Surprisingly at first, we\nfind compelling evidence for $\\theta = 0$, i.e., full energy-driven alignment\nin the equilibrium state of graphene on {\\it h}-BN. Two factors drive this\ndeviation from NM theory. First, graphene is not flat, developing on {\\it h}-BN\na long-wavelength out-of-plane corrugation. Second, {\\it h}-BN is not hard,\nreleasing its contact stress by planar contractions/expansions that accompany\nthe interface moir\\'e structure. Repeated simulations by artificially forcing\ngraphene to keep flat, and {\\it h}-BN to keep rigid, indeed yield an\nequilibrium misalignment similar to $\\theta_{NM}$ as expected. Subsequent\nsliding simulations show that friction of graphene on {\\it h}-BN, small and\nessentially independent of misalignments in the artificial frozen state,\nstrongly increases in the more realistic corrugated, strain-modulated, aligned\nstate."
    },
    {
        "anchor": "Incorporation of lanthanide ions into lead titanate: A series of lanthanide, Ln, ion doped lead titanate ceramics, at 2 and 8\nat.%, have been prepared with starting compositions Pb1-3x/2LnxTiO3, Ln = La,\nNd, Sm, Eu, Gd, Dy, using a standard ceramic method. Structural, and\ndifferential scanning calorimetry, measurements are reported. Doping with La3+\nresults in a reduction in tetragonality and cell volume; a partial recovery was\nthen observed for the smaller Ln3+ ions and suggests the onset of partial\nsubstitution of the rare earth on the B-site. The ferroelectric-paraelectric\ntransition temperature results also consistent with an increased probability\nthe B-site occupation with decreasing ion size.",
        "positive": "First Principles Phase Diagram Calculation for the 2D TMD system\n  $WS_{2}-WTe_{2}$: First principles phase diagram calculations, that included van der Waals\ninteractions, were performed for the bulk transition metal dichalcogenide\nsystem $(1-X) \\cdot WS_{2} - (X) \\cdot WTe_{2}$. To obtain a converged phase\ndiagram, a series of cluster expansion calculations were performed with\nincreasing numbers of structure-energies, ($N_{Str}$) up to $N_{Str}=435$, used\nto fit the cluster expansion Hamiltonian. All calculated formation energies are\npositive and all ground-state analyses predict that formation energies for\nsupercells with 16 or fewer anion sites are positive; but when $\\approx 150\nN_{Str} \\leq 376$, false ordered ground-states are predicted. With $N_{Str}\n\\geq 399$, only a miscibility gap is predicted, but one with dramatic asymmetry\nopposite to what one expects from size-effect considerations; i.e. the\ncalculations predict more solubility on the small-ion S-rich side of the\ndiagram and less on the large-ion Te-rich side. This occurs because S-rich\nlow-energy metastable ordered configurations have lower energies than their\nTe-rich counterparts."
    },
    {
        "anchor": "Controlling surface morphologies by time-delayed feedback: We propose a new method to control the roughness of a growing surface, via a\ntime-delayed feedback scheme. As an illustration, we apply this method to the\nKardar-Parisi-Zhang equation in 1+1 dimensions and show that the effective\ngrowth exponent of the surface width can be stabilized at any desired value in\nthe interval [0.25,0.33], for a significant length of time. The method is quite\ngeneral and can be applied to a wide range of growth phenomena. A possible\nexperimental realization is suggested.",
        "positive": "Epitaxial Growth of Quasi-One-Dimensional Bismuth-Halide Chains with\n  Topological Non-Trivial Edge States: Quantum spin Hall insulators have one-dimensional (1D) spin-momentum locked\ntopological edge states (ES) inside the bulk band gap, which can serve as\ndissipationless channels for the practical applications in low consumption\nelectronics and high performance spintronics. However, the clean and atomically\nsharp ES serving as ideal 1D conducting channels are still lack. Here, we\nreport the formation of the quasi-1D Bi4I4 nanoribbons on the surface of\nBi(111) with the support of the graphene-terminated 6H-SiC(0001) and the direct\nobservations of the topological ES at the step edge by scanning tunneling\nmicroscopy and spectroscopic-imaging results. The ES reside surround the edge\nof Bi4I4 nanoribbons and exhibits remarkable robustness against non time\nreversal symmetry perturbations. The theoretical simulations verify the\ntopological non-trivial character of 1D ES, which is retained after considering\nthe presence of the underlying Bi(111). Our study supports the existence of\ntopological ES in Bi4I4 nanoribbons, paving the way to engineer the novel\ntopological features by using the nanoribbons as the 1D building block."
    },
    {
        "anchor": "Crystal structure and low-energy Einstein mode in ErV$_2$Al$_{20}$\n  intermetallic cage compound: Single crystals of a new ternary aluminide ErV$_2$Al$_{20}$ were grown using\na self-flux method. The crystal structure was determined by powder X-ray\ndiffraction measurements and Rietveld refinement, and physical properties were\nstudied by means of electrical resistivity, magnetic susceptibility and\nspecific heat measurements. These measurements reveal that ErV$_2$Al$_{20}$ is\na Curie-Weiss paramagnet down to 1.95 K with an effective magnetic moment\n$\\mu_{eff}$ = 9.27(1) $\\mu_B$ and Curie-Weiss temperature $\\Theta_{CW}$ =\n-0.55(4) K. The heat capacity measurements show a broad anomaly at low\ntemperatures that is attributed to the presence of a low-energy Einstein mode\nwith characteristic temperature $\\Theta_E$ = 44 K, approximately twice as high\nas in the isostructural 'Einstein solid' VAl$_{10.1}$.",
        "positive": "Enhanced superconductivity in bilayer PtTe$_2$ by alkali-metal\n  intercalations: Layered platinum tellurium (PtTe2) was recently synthesized with controllable\nlayer numbers down to a monolayer limit. Using ab initio calculations based on\nanisotropic Midgal-Eliashberg formalism, we show that by rubidium (Rb)\nintercalation, weak superconductivity in bilayer PtTe2 can be significantly\nboosted with superconducting Tc = 8 K in the presence of spin-orbit coupling\n(SOC). The intercalant on one hand mediates the interlayer coupling and serves\nas an electron donor, leading to large density of states at Fermi energy. On\nthe other hand, it increases the mass-enhancement parameter with\nelectron-phonon coupling strength comparable to that of Pt. The potassium\nintercalated bilayer PtTe2 has a comparable Tc to the case of Rb intercalation.\nThe relatively high Tc with SOC combined with experimental accessible crystal\nstructures suggest that these superconductors are promising platforms to study\nthe novel quantum physics associated with two-dimensional superconductivity,\nsuch as the recently proposed type-II Ising superconductivity."
    },
    {
        "anchor": "Impact of the Energy Landscape on the Ionic Transport of Disordered\n  Rocksalt Cathodes: Traditional approaches to identify ion-transport pathways often presume equal\nprobability of occupying all hopping sites and focus entirely on finding the\nlowest migration barrier channels between them. Although this strategy has been\napplied successfully to solid-state Li battery materials, which historically\nhave mostly been ordered frameworks, in the emerging class of disordered\nelectrode materials some Li-sites can be significantly more stable than others\ndue to a varied distribution of transition metal (TM) environments. Using\nkinetic Monte Carlo simulations, we show that in such cation-disordered\ncompounds only a fraction of the Li-sites connected by the so-called\nlow-barrier ``0-TM\" channels actually participate in Li-diffusion. The\nLi-diffusion behavior through these sites, which are determined primarily by\nthe voltage applied during Li-extraction, can be captured using an effective\nmigration barrier larger than that of the 0-TM barrier itself. The suppressed\npercolation due to cation disorder can decrease the ionic diffusion coefficient\nat room temperature by over 2 orders of magnitude.",
        "positive": "Low wavenumber Raman spectroscopy of highly crystalline MoSe2 grown by\n  chemical vapor deposition: Transition metal dichalcogenides (TMDs) have recently attracted attention due\nto their interesting electronic and optical properties. Fabrication of these\nmaterials in a reliable and facile method is important for future applications,\nas are methods to characterize material quality. Here we present the chemical\nvapor deposition of MoSe2 monolayer and few layer crystals. These results show\nthe practicality of using chemical vapor deposition to reliably fabricate these\nmaterials. Low frequency Raman spectra and mapping of shear and layer breathing\nmodes of MoSe2 are presented for the first time. We correlate the behavior of\nthese modes with layer number in the materials. The usefulness of low frequency\nRaman mapping to probe the symmetry, quality, and monolayer presence in CVD\ngrown 2D materials is emphasized."
    },
    {
        "anchor": "Phosphorene and Doped Monolayers Interfaced TiO$_2$ with Type-II Band\n  Alignments: Novel Excitonic Solar Cells: Phosphorene, a new elemental two dimensional (2D) material recently isolated\nby mechanical exfoliation, holds the feature of a direct band gap of around 2.0\neV, overcoming graphene's weaknesses (zero band gap) to realize the potential\napplication in optoelectronic devices. Constructing van der Waals\nheterostructures is an efficient approach to modulate the band structure, to\nadvance the charge separation efficiency, and thus to optimize the\noptoelectronic properties. Here, we theoretically investigated three type-II\nheterostructures based on perfect phosphorene and its doped monolayers\ninterfaced with TiO$_2$(110) surface. Doping in phosphorene has a tunability on\nbuilt-in potential, charge transfer, light absorbance, as well as electron\ndynamics, which helps to optimize the light absorption efficiency. Three\nexcitonic solar cells (XSCs) based on the phosphorene$-$TiO$_2$ heterojunctions\nhave been proposed, which exhibit high power conversion efficiencies dozens of\ntimes higher than conventional solar cells, comparable to MoS$_2$/WS$_2$ XSC.\nThe nonadiabatic molecular dynamics within the time-dependent density\nfunctional theory framework shows ultrafast electron transfer time of\n6.1$-$10.8 fs, and slow electron$-$hole recombination of 0.58$-$1.08 ps,\nyielding $>98\\%$ quantum efficiency for charge separation, further guaranteeing\nthe practical power conversion efficiencies in XSC.",
        "positive": "Ultra-fast electric field control of giant electrocaloric effect in\n  ferroelectrics: There is a surge of interest in developing environmentally friendly cooling\ntechnology based on the solid--state electrocaloric effect (ECE). Here, we\npoint out that negative ECE with a fast cooling rate ($\\approx$10$^{11}$ K/s)\ncan be achieved by driving solid crystals to a high--temperature phase with a\nproperly designed electric field pulse. Specifically, we predict that an\nultrafast electric field pulse can cause a negative ECE up to 35 K in PbTiO$_3$\noccurring on few picosecond time scales. We acquire and analyze these results\nby clarifying the mechanism of ECE during an adiabatic irreversible process; In\naddition to the conventional explanation of the ECE with entropy reallocation,\nwe simply portray the ECE with the concept of internal energy redistribution.\nElectric field does work on a ferroelectric crystal and redistributes its\ninternal energy. How the kinetic energy is redistributed determines the\ntemperature change and strongly depends on the electric field temporal profile.\nThis concept is supported by our all--atom molecular dynamics simulations of\nPbTiO$_3$ and BaTiO$_3$. Based on this improved understanding of ECE, we\npropose strategies for inducing both giant and negative ECE. This work offers a\nmore general framework to understand the ECE and highlights the opportunities\nof electric--field engineering for controlled design of fast and efficient\ncooling technology."
    },
    {
        "anchor": "Phonon hydrodynamics in crystalline GeTe at low temperature: A first-principles density functional method along with the direct solution\nof linearized Boltzmann transport equations are employed to systematically\nanalyze the low-temperature thermal transport in crystalline GeTe. The\nextensive thermal transport simulations, ranging from room temperature to\ncryogenic temperatures, reveal the emergence of a phonon hydrodynamic regime in\nGeTe at low temperature. The reduction of grain boundary scattering is found to\nplay a crucial role along with the divergent trend of umklapp and normal\nscattering at low temperatures in accommodating the hydrodynamic regime.\nAverage scattering rates for normal, umklapp, and other resistive processes are\ndistinguished for a wide range (4-300 K) of temperatures and used for\nidentifying various phonon transport regimes. Therefore, the variations of\nlattice thermal conductivity, phonon propagation length, and thermal\ndiffusivity with temperature, related to these transport regimes (ballistic,\nhydrodynamic, and kinetic), have been thoroughly investigated. The modewise\ndecomposition of lattice thermal conductivity and the distinction of thermal\ndiffusivity according to different scattering processes reveal rich information\non the dominant phonon modes and phonon scattering processes in GeTe at low\ntemperature. Further, the kinetic-collective model is used to elucidate the\nhydrodynamic behavior of phonon scattering through the relative study of\ncollective and kinetic contributions to the thermal transport properties. In\nthis context, the Knudsen number is estimated through the characteristic\nnonlocal length and the grain size, which further quantifies the consistent\nhydrodynamic behavior of phonon thermal transport for GeTe. Finally,\nphonon-vacancy scattering for GeTe is realized, and vacancies are found\nstrongly to influence the hydrodynamic window while incorporating the other\nresistive scattering mechanisms.",
        "positive": "General segregation and chemical ordering in bimetallic nanoclusters\n  through atomistic view points: We predict general trends for surface segregation in a binary metal cluster\nbased on the difference between the atomic properties of the constituent\nelements. Considering the attractive and repulsive contributions of the\ncohesive energy of an atom in a cluster, energetically most favorable sites for\na guest atom on a pure metal cluster is determined. It is predicted that for\nadjacent elements in a row of the periodic table, the bimetallic system would\nbe more stable if the component with smallest valence electron density is\nplaced on the surface. On the contrary, for well separated components in the\nperiodic table, the bimetallic cluster would be more stable if the component\nwith the smallest core electron density is placed inside. Such chemical {\\bf\nordering trends} in the lowest energy configurations of Pt-Au, Pt-Pd and Pt-Ni\nbinary alloy clusters are verified for their 561 atom systems through simulated\nannealing process. It is predicted that the Ir, Rh, Ni, Pd atoms would tend to\nbe located inside the Ir-Pt, Rh-Pd, Ni-Cu and Pd-Ag bimetallic nanoclusters,\nrespectively."
    },
    {
        "anchor": "Thermal Expansion in 3d-Metal Prussian Blue Analogs - A Survey Study: We present a comprehensive study of the structural properties and the thermal\nexpansion behavior of 17 different Prussian Blue Analogs (PBAs) with\ncompositions MII3[(M')III(CN)6]2.nH2O and MII2[FeII(CN)6].nH2O, where MII = Mn,\nFe, Co, Ni, Cu and Zn, (M')III = Co, Fe and n is the number of water molecules,\nwhich range from 5 to 18 for these compounds. The PBAs were synthesized via\nstandard chemical precipitation methods, and temperature-dependent X-ray\ndiffraction studies were performed in the temperature range between -150oC (123\nK) and room-temperature. The vast majority of the studied PBAs were found to\ncrystallize in cubic structures of space groups, and . The temperature\ndependence of the lattice parameters was taken to compute an average\ncoefficient of linear thermal expansion in the studied temperature range. Of\nthe 17 compounds, 9 display negative values for the average coefficient of\nlinear thermal expansion, which can be as large as 39.7 x 10-6 K-1 for\nCo3[Co(CN)6]2.12H2O. All of the MII3[CoIII(CN)6]2.nH2O compounds show negative\nthermal expansion behavior, which correlates with the Irving-Williams series\nfor metal complex stability. The thermal expansion behavior for the PBAs of the\nMII3[FeIII(CN)6]2.nH2O family are found to switch between positive (for M = Mn,\nCo, Ni) and negative (M = Cu, Zn) behavior, depending on the choice of the\nmetal cation (M). On the other hand, all of the MII2[FeII(CN)6].nH2O compounds\nshow positive thermal expansion behavior.",
        "positive": "First-principles analysis of the optical properties of lead halide\n  perovskite solution precursors: Lead halide perovskites (LHPs) are promising materials for opto-electronics\nand photovoltaics, thanks to favorable characteristics and low manufacturing\ncosts enabled by solution processing. In light of this, it is crucial to assess\nthe impact of solvent-solute interactions on the electronic and optical\nproperties of LHPs and of their solution precursors. In a first-principles work\nbased on time-dependent density-functional theory coupled with the polarizable\ncontinuum model, we investigate the electronic and optical properties of a set\nof charge-neutral compounds with chemical formula, PbX$_2$(Sol)$_4$, where\nX=Cl, Br, and I, and Sol are the six common solvents. We find that\nsingle-particle energies and optical gaps depend on the halogen species as well\nas on the solvent molecules, which also affect the energy and the spatial\ndistribution of the molecular orbitals, thereby impacting on the excitations.\nWe clarify that dark states at the absorption onset are promoted by\nelectron-withdrawing solvents, and we show the correlation between oscillator\nstrength and HOMO$\\rightarrow$LUMO contribution to the excitations. Our results\nprovide microscopic insight into the electronic and optical properties of LHP\nsolution precursors, complementing ongoing experimental research on these\nsystems and on their evolution to photovoltaic thin films."
    },
    {
        "anchor": "Effect of Cd2+ on the Growth and Thermal Properties of K2SO4 crystal: Single crystals of pure and Cd2+ doped potassium sulfate were grown from\naqueous solutions by the slow evaporation technique. From nutrient solutions\nwith a CdSO4 concentration of 4wt.% crystals containing 0.014wt.% dopant\nconcentration could be obtained. The X-ray diffraction patterns of powdered\ncrystals confirmed their crystal structures for both cases. Thermal analysis of\npure crystals shows that the alpha-beta phase transformation peak around 580\ndeg C is superimposed with spurious effects, while for Cd2+ doped crystals this\nis not the case. The thermal hysteresis of the phase transition is 8 K for\nundoped K2SO4 and is reduced to 3.5 K for K2SO4:Cd2+. Compared to undoped\ncrystals, the optical transmittance of Cd2+ doped crystals is higher.",
        "positive": "Amorphous Boron Nitride: Ab initio Study of its vibrational properties: Boron nitride (BN) is a structurally versatile insulator since it can be\nfound in several crystalline structures with interesting mechanical and\nelectrical properties, making this material attractive for technological\napplications. Seeking to improve its features, experimental and simulational\nstudies for the amorphous phase (a-BN) have been carried out by some groups,\nfocusing on the electrical and structural properties, pressure-induced phase\ntransformations, and hydrogenated a-BN. In this work two amorphous structures\nare computationally generated and studied using ab initio Molecular Dynamics on\na 216-atom supercell with two different densities, 2.04 and 2.80 g cm$^{-3}$.\nOur undermelt-quench approach is followed, since it has proven to give good\nstructures for disordered materials and their properties. The topology, the\nvibrational density of states and some thermodynamic properties of the two\nsamples are reported and compared with existing experiment. Some computational\nresults are also revisited."
    },
    {
        "anchor": "Metal deficient AlB$_{2}$-type\n  (Ti$_{0.2}$Zr$_{0.2}$Hf$_{0.2}$Nb$_{0.2}$Ta$_{0.2}$)$_{1-\u03b4}$B$_{2}$\n  high-entropy diborides with high hardness: We report the synthesis and characterization of metal deficient\n(Ti$_{0.2}$Zr$_{0.2}$Hf$_{0.2}$Nb$_{0.2}$Ta$_{0.2}$)$_{1-\\delta}$B$_{2}$\nhigh-entropy diborides (HEBs). A single homogeneous AlB$_{2}$-type phase is\nsuccessfully obtained over the $\\delta$ range of 0.03 $\\leq$ $\\delta$ $\\leq$\n0.18. With increasing $\\delta$, the unit-cell volume exhibits a nonmonotonic\nvariation with a maximum at $\\delta$ = 0.07. These metal-deficient HEBs possess\nhigh Vickers hardness of 16.6-18.9 GPa at a load of 9.8 N and their phase\nstability is attributed to the increased mixing entropy. Our results not only\npresent the first series of metal-deficient AlB$_{2}$-type HEBs, but also\nsuggest the existence of similar multicomponent diborides.",
        "positive": "Mg substitution in CuCrO2 delafossite compounds: A detailed investigation of the series CuCr(1-x)MgxO2 (x = 0.0 - 0.05) has\nbeen performed by making high-temperature resistivity and thermopower\nmeasurements, and by performing a theoretical analysis of the latter.\nMicrostructure characterization has been carried out as well. Upon Mg2+ for\nCr3+ substitution, a concomitant decrease in the electrical resistivity and\nthermopower values is found, up to x ~ 0.02 - 0.03, indicating a low solubility\nlimit of Mg in the structure. This result is corroborated by scanning electron\nmicroscopy observations, showing the presence of MgCr2O4 spinels as soon as x =\n0.005. The thermopower is discussed in the temperature-independent correlation\nfunctions ratio approximation as based on the Kubo formalism, and the\ndependence of the effective charge carrier density on the nominal Mg\nsubstitution rate is addressed. This leads to a solubility limit of 1.1% Mg in\nthe delafossite, confirmed by energy dispersive X-ray spectroscopy analysis."
    },
    {
        "anchor": "On the use of aerogel as a soft acoustic metamaterial for airborne sound: Soft acoustic metamaterials utilizing mesoporous structures have recently\nbeen proposed as a novel means for tuning the overall effective properties of\nthe metamaterial and providing better coupling to the surrounding air. In this\nwork, the use of silica aerogel is examined theoretically and experimentally as\npart of a compact soft acoustic metamaterial structure, which enables a wide\nrange of exotic effective macroscopic properties to be demonstrated, including\nnegative density, density-near-zero and non-resonant broadband slow sound\npropagation. Experimental data is obtained on the effective density and sound\nspeed using an air-filled acoustic impedance tube for flexural metamaterial\nelements, which have previously only been investigated indirectly due to the\nlarge contrast in acoustic impedance compared to that of air. Experimental\nresults are presented for silica aerogel arranged in parallel with either 1 or\n2 acoustic ports, and are in very good agreement with the theoretical model.",
        "positive": "Magnetic vortex as a ground state for micron-scale antiferromagnetic\n  samples: Here we consider micron-sized samples with any axisymmetric body shape and\nmade with a canted antiferromagnet, like hematite or iron borate. We find that\nits ground state can be a magnetic vortex with a topologically non-trivial\ndistribution of the sublattice magnetization $\\vec{l}$ and planar coreless\nvortex-like structure for the net magnetization $\\vec{M}$. For\nantiferromagnetic samples in the vortex state, in addition to low-frequency\nmodes, we find high-frequency modes with frequencies over the range of hundreds\nof gigahertz, including a mode localized in a region of radius $\\sim$ 30--40 nm\nnear the vortex core."
    },
    {
        "anchor": "Direct observation of magnetic domain evolution in the vicinity of\n  Verwey transition in Fe3O4 thin films: We report a direct observation of magnetic domain evolution near the Verwey\ntransition (TV) in Fe3O4 films. We found the stripe domains in the\nFe3O4/Mg2TiO4 film while the irregular domains in the Fe3O4/MgO film and the\nsimilar characters of magnetic domains in the vicinity of TV for both samples:\nthe bigger domain size and the higher contrast of the phase signal below TV and\nthe more disordered domain images at TV. Remarkably, the magnetic behaviors can\nbe well understood and the domain-wall energy and the demagnetizing energy can\nbe calculated from the magnetic domains near TV in the Fe3O4/Mg2TiO4 film. Our\nwork presents a demonstration of the low temperature magnetic domains and gives\na new perspective to understand the Verwey transition in Fe3O4 thin films.",
        "positive": "Growth of 2D topological material Bi on InSb(111)B with fractal surface\n  structures: Bismuth (Bi) atomic layers are known as 2D topological materials with variety\nof the electronic structures and topological orders depending on the number of\nstacking layers. Recently, it is reported that few layers of Bi grown on\nsemiconductor substrate InSb(111)B exhibit the Sierpi\\'{n}ski-triangle (ST)\nfractal patterns on the surface. In this work, we have grown Bi layers on\nInSb(111)B and traced the evolution of the atomic and electronic structures of\nBi. The surface atomic structures and growth modes were monitored by using\nreflective high-energy electron diffraction and core-level photoelectron\nspectroscopy. It is suggested that the single layer of the ST-phase Bi grows on\nInSb(111)B and the following Bi deposition causes layer-by-layer growth up to\nnominally 4 atomic layers. Diffuse band dispersion and quantum well states\nobserved by angle-resolved photoelectron spectroscopy are consistent with the\nsmall surface domains and variation of the thickness even during the\nlayer-by-layer growth region. The further Bi evaporation changes the growth\nmode to the 3D island formation. The unveiled growth behavior of Bi on\nInSb(111)B would provide a new interesting playground to study 2D topological\nelectronic structure of quasi-periodic 2D atomic layers."
    },
    {
        "anchor": "Advanced Post-Processing Techniques of Molecular Dynamics Simulations in\n  Studying Strong Anharmonic Thermodynamics of Solids: While the vibrational thermodynamics of materials with small anharmonicity at\nlow temperatures has been understood well based on the harmonic phonons\napproximation; at high temperatures, this understanding must accommodate how\nphonons interact with other phonons or with other excitations. We shall see\nthat the phonon-phonon interactions give rise to interesting coupling problems,\nand essentially modify the equilibrium and non-equilibrium properties of\nmaterials, e.g., thermal expansion, thermodynamic stability, heat capacity,\noptical properties, thermal transport and other nonlinear properties of\nmaterials. To date the anharmonic lattice dynamics is poorly understood despite\nits great importance, and most studies on lattice dynamics still rely on the\nharmonic or quasiharmonic models. With recent developement of computational\nmodels, the anharmonic information can be extracted from the atomic\ntrajectories of molecular dynamics simulations. For example, the vibrational\nenergy spectra, the effective potential energy surface and the phonon-phonon\ninteraction channels can be derived from these trajectories which appear\nstochastic. These inter-dependent methods are adopted to successfully uncover\nthe strong anharmonic phenomena while the traditional harmonic models fail\ndramatically, e.g., the negative thermal expansion of cuprite and the high\ntemperature thermal stability of rutile.",
        "positive": "Impact of the inherent periodic structure on the effective medium\n  description of left-handed and related meta-materials: We study the frequency dependence of the effective electromagnetic parameters\nof left-handed and related meta-materials of the split ring resonator and wire\ntype. We show that the reduced translational symmetry (periodic structure)\ninherent to these meta-materials influences their effective electromagnetic\nresponse. To anticipate this periodicity, we formulate a periodic effective\nmedium model which enables us to distinguish the resonant behavior of\nelectromagnetic parameters from effects of the periodicity of the structure. We\nuse this model for the analysis of numerical data for the transmission and\nreflection of periodic arrays of split ring resonators, thin metallic wires,\ncut wires as well as the left-handed structures. The present method enables us\nto identify the origin of the previously observed resonance/anti-resonance\ncoupling as well as the occurrence of negative imaginary parts in the effective\npermittivities and permeabilities of those materials. Our analysis shows that\nthe periodicity of the structure can be neglected only for the wavelength of\nthe electromagnetic wave larger than 30 space periods of the investigated\nstructure."
    },
    {
        "anchor": "Energy landscape of relaxed amorphous silicon: We analyze the structure of the energy landscape of a well-relaxed 1000-atom\nmodel of amorphous silicon using the activation-relaxation technique (ART\nnouveau). Generating more than 40,000 events starting from a single minimum, we\nfind that activated mechanisms are local in nature, that they are distributed\nuniformly throughout the model and that the activation energy is limited by the\ncost of breaking one bond, independently of the complexity of the mechanism.\nThe overall shape of the activation-energy-barrier distribution is also\ninsensitive to the exact details of the configuration, indicating that\nwell-relaxed configurations see essentially the same environment. These results\nunderscore the localized nature of relaxation in this material.",
        "positive": "Efficient partitioning of surface Green's function: toward ab initio\n  contact resistance study: In this work, we propose an efficient computational scheme for\nfirst-principle quantum transport simulations to evaluate the open-boundary\nconditions. Its partitioning differentiates from conventional methods in that\nthe contact self-energy matrices are constructed on smaller building blocks,\nprincipal layers (PL), while conventionally it was restricted to have the same\nlateral dimensions of the adjoining atoms in a channel region. Here, we obtain\nthe properties of bulk electrodes through non-equilibrium Green's function\n(NEGF) approach with significant improvements in the computational efficiency\nwithout sacrificing the accuracy of results. To exemplify the merits of the\nproposed method we investigate the carrier density dependency of contact\nresistances in silicon nanowire devices connected to bulk metallic contacts."
    },
    {
        "anchor": "Structural metastability and Fermi surface Topology of SrAl2Si2: SrAl2Si2 crystallizes into either a semimetallic, CaAl2Si2-type, \\alpha phase\nor a superconducting, BaZn2P2-type, \\beta phase. We explore possible \\alpha\n--Pc;Tc--> \\beta transformations by employing pressure- and\ntemperature-dependent free-energy calculations, vibrational spectra\ncalculations, and room-temperature synchrotron X-ray powder diffraction (XRPD)\nmeasurements up to 14 GPa using diamond anvil cell. Our theoretical and\nempirical analyses together with all baric and thermal reported events on both\nphases allow us to construct a preliminary P-T diagram of transformations. Our\ncalculations show a relatively low critical pressure for the \\alpha to \\beta\ntransition (4.9 GPa at 0 K, 5.0 GPa at 300 K and 5.3 GPa at 900 K);\nnevertheless, our nonequilibrium analysis indicates that the\nlow-pressure-low-temperature \\alpha phase is separated from metastable \\beta\nphase by a relatively high activation barrier. This analysis is supported by\nour XRPD data at ambient temperature and P < 14 GPa which shows an absence of\n\\beta phase even after a compression involving three times the critical\npressure. Finally, we briefly consider the change in Fermi surface topology\nwhen atomic rearrangement takes place via either transformations among\nSrAl2Si2-dimorphs or total chemical substitution of Ca by Sr in isomorphous\n\\alpha CaAl2Si2; empirically, manifestation of such topology modification is\nevident when comparing the evolution of (magneto-)transport properties of\nmembers of SrAl2Si2-dimorphs and \\alpha isomorphs.",
        "positive": "Charged surfaces and slabs in periodic boundary conditions: Plane wave density functional theory codes generally assume periodicity in\nall three dimensions. This causes difficulties when studying charged systems,\nfor instance energies per unit cell become infinite, and, even after being\nrenormalised by the introduction of a uniform neutralising background, are very\nslow to converge with cell size. The periodicity introduces spurious electric\nfields which decay slowly with cell size and which also slow the convergence of\nother properties relating to the ground state charge density. This paper\npresents a simple self-consistent technique for producing rapid convergence of\nboth energies and charge distribution in the particular geometry of 2D\nperiodicity, as used for studying surfaces."
    },
    {
        "anchor": "Investigation of process history and phenomenology of plutonium oxides\n  using vector quantizing variational autoencoder: Accurate, high throughput, and unbiased analysis of plutonium oxide particles\nis needed for analysis of the phenomenology associated with process parameters\nin their synthesis. Compared to qualitative and taxonomic descriptors,\nquantitative descriptors of particle morphology through scanning electron\nmicroscopy (SEM) have shown success in analyzing process parameters of uranium\noxides. We utilize a VQ-VAE to quantitatively describe plutonium dioxide (PuO2)\nparticles created in a designed experiment and investigate their phenomenology\nand prediction of their process parameters. PuO2 was calcined from Pu(III)\noxalates that were precipitated under varying synthetic conditions that related\nto concentrations, temperature, addition and digestion times, precipitant feed,\nand strike order; the surface morphology of the resulting PuO2 powders were\nanalyzed by SEM. A pipeline was developed to extract and quantify useful image\nrepresentations for individual particles with the VQ-VAE to perform multiple\nclassification tasks simultaneously. The reduced feature space could predict\nprocess parameters with greater than 80% accuracies for some parameters with a\nsingle particle. They also showed utility for grouping particles with similar\nsurface morphology characteristics together. Both the clustering and\nclassification results reveal valuable information regarding which chemical\nprocess parameters chiefly influence the PuO2 particle morphologies: strike\norder and oxalic acid feedstock. Doing the same analysis with multiple\nparticles was shown to improve the classification accuracy on each process\nparameter over the use of a single particle, with statistically significant\nresults generally seen with as few as four particles in a sample.",
        "positive": "New off-lattice Pattern Recognition Scheme for off-lattice kinetic Monte\n  Carlo Simulations: We report the development of a new pattern-recognition scheme for the off-\nlattice self-learning kinetic Monte Carlo (KMC) method that is simple and flex\nible enough that it can be applied to all types of surfaces. In this scheme, to\nuniquely identify the local environment and associated processes involving\nthree-dimensional (3D) motion of an atom or atoms, 3D space around a central\natom or leading atom is divided into 3D rectangular boxes. The dimensions and\nthe number of 3D boxes are determined by the type of the lattice and by the ac-\ncuracy with which a process needs to be identified. As a test of this method we\npresent the application of off-lattice KMC with the pattern-recognition scheme\nto 3D Cu island decay on the Cu(100) surface and to 2D diffusion of a Cu\nmonomer and a dimer on the Cu (111) surface. We compare the results and\ncomputational efficiency to those available in the literature."
    },
    {
        "anchor": "Electronic transport calculations for lightly-doped thermoelectrics\n  using density functional theory: Application to high-performing Cu-doped zinc\n  antimonides: We propose a new method for accurately calculating electrical transport\nproperties of a lightly-doped thermoelectric material from density functional\ntheory (DFT) calculations, based on experimental data and density functional\ntheory results for the corresponding undoped material. We employ this approach\nbecause hybrid DFT calculations are prohibitive for the large supercells\nrequired to model low dopant concentrations comparable to those achieved\nexperimentally for high-performing thermoelectrics. Using zinc antimonide as\nour base material, we find that the electrical transport properties calculated\nwith DFT and Boltzmann transport theory exhibit the same trends with changes in\nchemical potential as those computed with hybrid DFT, and propose a fitting\nalgorithm that involves adjusting the computed Fermi energy so that the\nresulting Seebeck coefficient trends with temperature match experimental\ntrends. We confirm the validity of this approach in reproducing the\nexperimental trends in electrical conductivity and Seebeck coefficient versus\ntemperature for Bi-doped $\\beta-$Zn$_4$Sb$_3$. We then screen various\ntransition metal cation dopants, including copper and nickel, and find that a\nCu dopant concentration of 2.56% in Zn$_{39}$Sb$_{30}$ exhibited a 14% increase\nin the thermoelectric power factor for temperatures between 300-400 K. We thus\npropose that transition metal dopants may significantly improve the\nthermoelectric performance of the host material, compared to heavy and/or\nrare-earth dopants.",
        "positive": "First-principle prediction of Martensitic transformation and magnetic\n  properties of Heusler-type Pt2-xMn1+xGa alloys: The electronic structure, magnetism and phase stability of Pt2-xMn1+xGa(x=0,\n0.25, 0.5, 0.75, 1) alloys are studied by first-principle calculations. The\ncalculations reveal that a potential magnetic martensitic transformation can be\nexpected in all the series. In addition, a large magnetic-field-induced strain\nis likely to appear in Pt2-xMn1+xGa(x=0, 0.25, 0.75, 1) alloys. The electronic\nstructure calculations indicate that the tetragonal phase is stabilized upon\nthe distortion because of the pseudogap formation at the Fermi Level. The\nmagnetic structure is also investigated and the total magnetic moment of the\ntetragonal phase is a little larger than that of the cubic austenite phase in\nall the series."
    },
    {
        "anchor": "Spin orbital reorientation transitions induced by magnetic field: Here we report on a new effect similar to the spin reorientation transition\n(SRT) that takes place at two magnetic fields of $B_{SORT1}$ and $B_{SORT2}$.\nThe effect is observed in the magnetization curves of small Mn$^{3+}$ magnetic\nclusters in the wurtzite GaN (being in a paramagnetic state) calculated using\ncrystal field model approach. The obtained results suggest that the computed\nmagnetic anisotropy (MA) reverses its sign on increasing $B$ across $B_{SORT}$.\nDetailed analysis show however that MA is unchanged for high magnetic fields.\nWe show that the observed effect arises from the interplay of the crystalline\nenvironment and the spin-orbit coupling $\\lambda \\hat{\\textbf{S}}\n\\hat{\\textbf{L}}$, therefore we name it spin orbital reorientation transition\n(SORT). The value of $B_{SORT1}$ depends on the crystal field model parameters\nand the number of ions $N$ in a given cluster, whereas $B_{SORT2}$ is\ncontrolled mostly by the magnitude of the spin-orbit coupling $\\lambda$. The\nexplanation of SORT is given in terms of the spin $M_S$ and orbital momentum\n$M_L$ contributions to the total magnetization $M = M_S + M_L$. The similar\neffect should also be present in other materials with not completely quenched\n(non zero) orbital angular momentum $L$, a uniaxial magnetic anisotropy and the\npositive value of $\\lambda$.",
        "positive": "Electroabsorption study of index-defined semiconducting carbon nanotubes: Electroabsorption spectroscopy of well-identified index-defined\nsemiconducting carbon nanotubes is reported. The measurement of high definition\nelectroabsorption spectra allows direct indexation with unique nanotube\nchirality. Results show that at least for a limited range of diameters,\nelectroabsorption is directly proportional to the exciton binding energy of\nnanotubes. Electroabsorption is a powerful technique which directly probes into\ncarbon nanotube excitonic states, and may become a useful tool for in situ\nstudy of excitons in future nanotube-based photonic devices such as\nelectroabsorption modulators."
    },
    {
        "anchor": "Graphene-based light sensing: fabrication, characterisation, physical\n  properties and performance: Graphene and graphene-based materials exhibit exceptional optical and\nelectrical properties with great promise for novel applications in light\ndetection. However, several challenges prevent the full exploitation of these\nproperties in commercial devices. Such challenges include the limited linear\ndynamic range (LDR) of graphene-based photodetectors, the lack of efficient\ngeneration and extraction of photoexcited charges, the smearing of photoactive\njunctions due to hot-carriers effects, large-scale fabrication and ultimately\nthe environmental stability of the constituent materials. In order to overcome\nthe aforementioned limits, different approaches to tune the properties of\ngraphene have been explored. A new class of graphene-based devices has emerged\nwhere chemical functionalisation, hybridisation with light-sensitising\nmaterials and the formation of heterostructures with other 2D materials have\nled to improved performance, stability or versatility. For example,\nintercalation of graphene with FeCl$_3$ is highly stable in ambient conditions\nand can be used to define photo-active junctions characterized by an\nunprecedented LDR while graphene oxide (GO) is a very scalable and versatile\nmaterial which supports the photodetection from UV to THz frequencies.\nNanoparticles and quantum dots have been used to enhance the absorption of\npristine graphene and to enable high gain thanks to the photogating effect. In\nthe same way, hybrid detectors made from stacked sequences of graphene and\nlayered transition-metal dichalcogenides enabled a class of detectors with high\ngain and responsivity. In this work we will review the performance and advances\nin functionalised graphene and hybrid photodetectors, with particular focus on\nthe physical mechanisms governing the photoresponse in these materials, their\nperformance and possible future paths of investigation.",
        "positive": "The study of adsorption behaviour of a laser dye incorporated into ultra\n  thin films: Here we report the adsorption behaviour of a water soluble laser dye\nrhodamine onto ultrathin films prepared by LB technique without altering its\nphotophysical behabiour."
    },
    {
        "anchor": "Evanescent waves in photonic crystals and image of Veselago lens: It is shown that negative electric permittivity and magnetic permeability\nrecently discovered in a photonic crystal in the vicinity of the Gamma-point\nare properties of propagating modes only. The evanescent modes rather decay\nthan increase in the bulk of the crystal though they may be amplified by\nsurface waves. If surface support such waves, the evanescent waves may improve\nthe image of a thin Veselago lens. It is shown that a ``perfect lens''\ncontradicts to the wave optics and a criterion of ``superlensing'' is\nformulated.",
        "positive": "DOS-limited contact resistance in graphene FETs: Graphene has attracted much attention as one of promising candidates of\nfuture high-speed transistor materials because of its high carrier mobility of\nmore than 10,000 cm2 V-1 s-1. Up to this point, we have focused on the contact\nproperties as performance killers, as a very small density of states in\ngraphene might suppress the current injection from metal to graphene. This\npaper systematically reviews the metal/graphene contact properties and\ndiscusses the present status and future requirements of the specific contact\nresistivity."
    },
    {
        "anchor": "Optimization of Spatial Dose Distribution for Controlling Sidewall Shape\n  in Electron-beam Lithography: Electron-beam (e-beam) lithography is widely employed in fabrication of 2-D\npatterns and 3-D structures. A certain type or shape of the sidewall in the\nremaining resist profile may be desired in an application, e.g., an undercut\nfor lift-off and a vertical sidewall for etching, or required for a device.\nAlso, as the feature size is decreased well below a micron, a small variation\nof the sidewall slope can lead to a significant (relative) CD error in certain\nlayers of resist. Therefore, it is important to understand effects of spatial\ndose distribution on sidewall shape and be able to achieve the desired shape.\nIn this study, via simulation, the relationship among the total dose, spatial\ndistribution of dose, developing time and sidewall shape, and performance of\nthe method developed to optimize the dose distribution for a target sidewall\nshape have been analyzed. The simulation results have been verified through\nexperiments.",
        "positive": "Complete Strain Mapping of Nanosheets of Tantalum Disulfide: Quasi-two-dimensional (quasi-2D) materials hold promise for future\nelectronics because of their unique band structures that result in electronic\nand mechanical properties sensitive to crystal strains in all three dimensions.\nQuantifying crystal strain is a prerequisite to correlating it with the\nperformance of the device, and calls for high resolution but spatially resolved\nrapid characterization methods. Here we show that using fly-scan nano X-ray\ndiffraction we can accomplish a tensile strain sensitivity below 0.001% with a\nspatial resolution of better than 80 nm over a spatial extent of 100 $\\mu$m on\nquasi 2D flakes of 1T-TaS2. Coherent diffraction patterns were collected from a\n$\\sim$ 100 nm thick sheet of 1T-TaS2 by scanning 12keV focused X-ray beam\nacross and rotating the sample. We demonstrate that the strain distribution\naround micron and sub-micron sized 'bubbles' that are present in the sample may\nbe reconstructed from these images. The experiments use state of the art\nsynchrotron instrumentation, and will allow rapid and non-intrusive strain\nmapping of thin film samples and electronic devices based on quasi 2D\nmaterials."
    },
    {
        "anchor": "The Serrated-Flow Behavior in High-Entropy Alloys: This chapter presents a literature review of the serrated flow phenomenon in\nhigh-entropy alloys (HEAs). The serrated flow is important as it can result in\npermanent macroscopic and microstructural changes in HEAs. The literature\nreveals several important findings regarding the effect of strain rate and test\ntemperature on the serrated flow. Furthermore, this chapter explores the\nrelationship among the composition, microstructure, testing condition, and\nserration behavior. Towards the end of the chapter, a concise summary is\npresented for the temperature, strain rate, mechanical-testing type\n(compression/tension/nanoindentation), and serration type for HEAs. This\nchapter also provides an overview of the different types of analytical methods\nthat have been successfully implemented to model and analyze the serration\nbehavior in HEAs. Such techniques include the mean-field theory (MFT)\nformalism, complexity-analysis method, and multifractal technique. Finally,\nfuture research topics in this area are presented, such as the effects of\ntwinning and irradiation on the serration behavior.",
        "positive": "Topological Analysis of Foams and tetrahedral structures: In this paper we characterize foams and tetrahedral structures in a unified\nway, by a simplified representation of both that conserves the system topology.\nThe paper presents a workflow for an automated characterization of the topology\nof the void space, using a partition of the void space into polyhedral cells\nconnected by windows. This characterization serves as the basic input for the\nEdwards entropic formalism that deals with the statistical characterization of\nconfigurational disorder in granular aggregates and argued to work for foams.\nThe Edwards formalism is introduced and simplified expectation values are\ncalculated."
    },
    {
        "anchor": "Efficient Calculation of Derivatives of Integrals in a Basis of\n  Non-Separable Gaussians Through Exploitation of Sparsity: A computational procedure is developed for the efficient calculation of\nderivatives of integrals over non-separable Gaussian-type basis functions, used\nfor the evaluation of gradients of the total energy in quantum-mechanical\nsimulations. The approach, based on symbolic computation with computer algebra\nsystems and automated generation of optimized subroutines, takes full advantage\nof sparsity and is here applied to first energy derivatives with respect to\nnuclear displacements and lattice parameters of molecules and materials. The\nimplementation in the \\textsc{Crystal} code is presented and the considerably\nimproved computational efficiency over the previous implementation is\nillustrated. To this purpose, three different tasks involving the use of\nanalytical forces are considered: i) geometry optimization; ii) harmonic\nfrequency calculation; iii) elastic tensor calculation. Three test case\nmaterials are selected as representatives of different classes: i) a metallic\n2D model of the Cu (111) surface; ii) a wide-gap semiconductor ZnO crystal,\nwith a wurtzite-type structure; and iii) a porous metal-organic crystal, namely\nthe ZIF-8 Zinc-imidazolate framework. Finally, it is argued that the present\nsymbolic approach is particularly amenable to generalizations, and its\npotential application to other derivatives is sketched.",
        "positive": "Defects in Cd3As2 Epilayers Via Molecular Beam Epitaxy and Strategies\n  for Reducing Them: Molecular beam epitaxy offers an exciting avenue for investigating the\nbehavior of topological semimetal Cd3As2, by providing routes for doping,\nalloying, strain engineering, and heterostructure formation. To date, however,\nminimal exploration has been devoted to the impact of defects that are\nincorporated into epilayers due to contraints imposed by the substrate and\nnarrow growth window. Here, we use a combination of lattice-matched ZnxCd1-xTe\nbuffer layers, miscut substrates and broadband illumination to study how\ndislocations, twins and point defects influence the electron mobility of\nCd3As2. A combination of defect suppression approaches produces Cd3As2\nepilayers with electron mobilities upwards of 15,000 cm2/V-s at room\ntemperature."
    },
    {
        "anchor": "First-principles study of the stability of free-standing germanene in\n  oxygen: The O2 dissociation and O atoms adsorption on free-standing germanene are\nstudied by using first-principles calculations in this letter. Compared with\nthe spontaneous dissociation of oxygen molecule on free-standing silicene in\nair, germanene is more stable than silicene from kinetic point of view, with\novercoming energy barrier of about 0.55 eV. Especially, in contrast with the\nunique chemical adsorption of O2-dissociation-induced O atoms on silicene,\noxygen molecule can behave a correspondingly stable adsorption on germanene\nsurface. Moreover, single O atom adsorption on germanene is also different to\nthat on silicene, resulting in two opposite migration pathways on germanene\nsurface. Furthermore, once the oxygen molecule dissociates into O atoms on\ngermanene surface, the migration and desorption of O atoms are relatively\ndifficult under room temperature due to the strong Ge-O bonds in the O-adsorbed\ngermanene, in favor of forming germanium oxides. The results provide compelling\nevidence to show that free-standing gemanene is relatively stable in\noxygen,which is different to silicene essentially.",
        "positive": "Theory of Graphene Raman Spectroscopy: Raman spectroscopy plays a key role in studies of graphene and related carbon\nsystems. Graphene is perhaps the most promising material of recent times for\nmany novel applications, including electronics. In this paper, the traditional\nand well established Kramers-Heisenberg-Dirac (KHD) Raman scattering theory\n(1925-1927) is extended to crystalline graphene for the first time. It demands\ndifferent phonon production mechanisms and phonon energies than does the\npopular \"double resonance\" Raman scattering model. The latter has never been\ncompared to KHD. Within KHD, phonons are produced instantly along with\nelectrons and holes, in what we term an electron-hole-phonon triplet, which\ndoes not suffer Pauli blocking. A new mechanism for double phonon production we\nname \"transition sliding\" explains the brightness of the 2D mode and other\novertones, as a result of linear (Dirac cone) electron dispersion. Direct\nevidence for sliding resides in hole doping experiments performed in 2011\n\\cite{chenCrommie}. Whole ranges of electronic transitions are permitted and\nmay even constructively interfere for the same laser energy and phonon q,\nexplaining the dispersion, bandwidth, and strength of many two phonon Raman\nbands. Graphene's entire Raman spectrum, including dispersive and fixed bands,\nmissing bands not forbidden by symmetries, weak bands, overtone bands, Stokes\nanti-Stokes anomalies, individual bandwidths, trends with doping, and D-2D band\nspacing anomalies emerge naturally and directly in KHD theory."
    },
    {
        "anchor": "Multipole expansion of continuum dislocations dynamics in terms of\n  alignment tensors: Dislocation based modeling of plasticity is one of the central challenges at\nthe crossover of materials science and continuum mechanics. Developing a\ncontinuum theory of dislocations requires the solution of two long standing\nproblems: (i) to find a faithful representation of dislocation kinematics with\na reasonable number of variables and (ii) to derive averaged descriptions of\nthe dislocation dynamics (i.e. material laws) in terms of these variables. In\nthe current paper we solve the first problem. This is achieved through a\nmultipole expansion of the dislocation density in terms of so-called alignment\ntensors containing the directional distribution of dislocation density and\ndislocation curvature. A hierarchy of evolution equations of these tensors is\nderived from a higher dimensional dislocation density theory. Low order closure\napproximations of this hierarchy lead to continuum dislocation dynamics models\nwith only few internal variables. Perspectives for more refined theories and\ncurrent challenges in dislocation density modeling are discussed.",
        "positive": "Bond Synergy Model for Bond Energies in Alloy Oxides: In this work we introduce a metal-oxide bond-energy model for alloy oxides\nbased on pure-phase bond energies and bond synergy factors that describe the\neffect of alloying on the bond energy between cations and oxygen, an important\nquantity to understand formation and stability of passive films. This model is\nparameterized for binary cation-alloy oxides using density-functional theory\nenergies and is shown to be directly transferable to multi-component alloy\noxides. We parameterized the model for alloy oxide energies with metal cations\nthat form the basis of corrosion resistant alloys, including Fe, Ni, Cr, Mo,\nMn, W, Co, and Ru. We find that isoelectronic solutes allow quantification of\npure-phase bond energies in oxides and that the calculated bond energy values\ngive sensible results compared to common experience, including the role of Cr\nas the passive-layer former in Fe-Ni-Cr alloys for corrosion applications.\nAdditionally, the bond synergy factors give insights into the mutual\nstrengthening and weakening effects of alloying on cation-oxygen bonds and can\nbe related to enthalpy of mixing and charge neutrality constraints. We\ndemonstrate how charge neutrality can be identified and achieved by the\noxidation states that the different cations assume depending on alloy\ncomposition and the presence of defects."
    },
    {
        "anchor": "Deep Reinforcement Learning for Inverse Inorganic Materials Design: A major obstacle to the realization of novel inorganic materials with\ndesirable properties is the inability to perform efficient optimization across\nboth materials properties and synthesis of those materials. In this work, we\npropose a reinforcement learning (RL) approach to inverse inorganic materials\ndesign, which can identify promising compounds with specified properties and\nsynthesizability constraints. Our model learns chemical guidelines such as\ncharge and electronegativity neutrality while maintaining chemical diversity\nand uniqueness. We demonstrate a multi-objective RL approach, which can\ngenerate novel compounds with targeted materials properties including formation\nenergy and bulk/shear modulus alongside a lower sintering temperature synthesis\nobjectives. Using this approach, the model can predict promising compounds of\ninterest, while suggesting an optimized chemical design space for inorganic\nmaterials discovery.",
        "positive": "Polarizable particles aggregation under rotating magnetic fields using\n  scattering dichroism: We used scattering dichroism to study the combined effects of viscous and\nmagnetic forces on the dynamics of dipolar chains induced in magnetorheological\nsuspensions under rotating magnetic fields. We found that the chains adjust\ntheir size to rotate synchronously with the field but with a constant phase\nlag. Two different behaviors for the dichroism (proportional to the total\nnumber of aggregated particles) and the phase lag are found below or above a\ncritical frequency. We obtained a linear dependence of the critical frequency\nwith the square of the magnetization and with the inverse of the viscosity. The\nMason number (ratio of viscous to magnetic forces) governs the dynamics.\nTherefore there is a critical Mason number below which, the dichroism remains\nalmost constant and above which, the rotation of the field prevents the\nparticle aggregation process from taken place being this the mechanism\nresponsible for the decrease of dichroism. Our experimental results have been\ncorroborated with particle dynamics simulations showing good agreement."
    },
    {
        "anchor": "Disassembling of TEMPO-oxidized cellulose fibers: intersheet and\n  interchain interactions in the isolation of nanofibers and unitary chains: Cellulose disassembly is an important issue in designing nanostructures using\ncellulose-based materials. In this work, we present a joint of experimental and\ntheoretical study addressing the disassembly of cellulose nanofibrils. Through\n2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) mediated oxidation processes,\ncombined with atomic force microscopy results, we find the formation of\nnanofibers with diameters corresponding to a single cellulose polymer chain.\nThe formation of these polymer chains is ruled by repulsive electrostatic\ninteractions between the oxidized chains. Further first-principles calculations\nhave been done in order to provide an atomistic understanding the cellulose\ndisassembling processes, focusing on the balance of the interchain and\nintersheet interactions upon oxidation. Firstly we analyse these interaction in\npristine systems, where we found the intersheet interaction stronger than the\ninterchain one. In the oxidized systems, we have considered the formation of\n(charged) carboxylate groups along the inner sites of elementary fibrils. We\nshow a net charge concentration on the carboxylate groups, supporting the\nemergence of repulsive electrostatic interactions between the cellulose\nnanofibers. Indeed, our total energy results show that the weakening of the\nbinding strength between the fibrils is proportional to the concentration and\nthe net charge density of the carboxylate group. Moreover, by comparing\ninterchain and intersheet binding energies, we found that most of the\ndisassembly processes should take place by breaking the interchain\nO--H$\\cdots$O hydrogen bond interactions, and thus supporting the experimental\nobservation of single and double cellulose polymeric chains.",
        "positive": "Fully dry PMMA transfer of graphene on h-BN using a heating/cooling\n  system: The key to achieve high-quality van der Waals heterostructure devices made of\nstacking various two-dimensional (2D) layered materials lies in the clean\ninterface without bubbles and wrinkles. Although polymethylmethacrylate (PMMA)\nis generally used as a sacrificial transfer film due to its strong adhesion\nproperty, it is always dissolved in the solvent after the transfer, resulting\nin the unavoidable PMMA residue on the top surface. This makes it difficult to\nlocate clean interface areas. In this work, we present a fully dry PMMA\ntransfer of graphene onto h-BN using a heating/cooling system which allows\nidentification of clean interface area for high quality graphene/h-BN\nheterostructure fabrication. The mechanism lies in the utilization of the large\ndifference in thermal expansion coefficients between polymers (PMMA/PDMS) and\ninorganic materials (graphene/h-BN substrate) to mechanically peel off PMMA\nfrom graphene by the thermal shrinkage of polymers, leaving no PMMA residue on\nthe graphene surface. This method can be applied to all types of 2D layered\nmaterials."
    },
    {
        "anchor": "Topological Critical Point and Resistivity Anomaly in HfTe5: There is a long-standing confusion concerning the physical origin of the\nanomalous resistivity peak in transition metal pentatelluride HfTe5. Several\nmechanisms, like the formation of charge density wave or polaron, have been\nproposed, but so far no conclusive evidence has been presented. In this work,\nwe investigate the unusual temperature dependence of magneto-transport\nproperties in HfTe5. We find that a three dimensional topological Dirac\nsemimetal state emerges only at around Tp (at which the resistivity shows a\npronounced peak), as manifested by a large negative magnetoresistance. This\naccidental Dirac semimetal state mediates the topological quantum phase\ntransition between the two distinct weak and strong topological insulator\nphases in HfTe5. Our work not only provides the first evidence of a\ntemperature-induced critical topological phase transition in HfTe5, but also\ngives a reasonable explanation on the long-lasting question.",
        "positive": "Comment on ``Method to analyze electromechanical stability of dielectric\n  elastomers\" [Appl. Phys. Lett. 91, 061921 (2007)]: The model of Zhao and Suo can be readily generalized to predict the critical\nbreakdown electric field $E_c$ value of elastomers with arbitrary elastic\nstrain energy function. An explicit expression for $E_c$ is presented for\nelastomeric thin films under biaxial strain and comparisons are made with\nexperimental data using a two term Ogden rubber elasticity model. Simplified\nresults for uniaxial and for equi-biaxial stress provide further insight into\nthe findings of Zhao and Suo."
    },
    {
        "anchor": "Interface ferromagnetism and anomalous Hall effect of CdO/ferromagnetic\n  insulator heterostructures: The experimental observation of quantum anomalous Hall effect (QAHE) in\nmagnetic topological insulators has stimulated enormous interest in\ncondensed-matter physics and materials science. For the purpose of realizing\nhigh-temperature QAHE, several material candidates have been proposed, among\nwhich the interface states in the CdO/ferromagnetic insulator heterostructures\nare particularly interesting and favorable for technological applications.\nHere, we report the experimental observation of the interfacial ferromagnetism\nand anomalous Hall effect in the Fe3O4/CdO/Fe3O4 heterostructures grown via\noxide molecular-beam epitaxy. Systematical variation of the CdO thickness\nreveals the interface ferromagnetism as the major cause for the observed planar\nmagnetoresistance and anomalous Hall effect. Our results might pave the way to\nengineer oxide interface states for the exploration of QAHE towards exotic\nquantum-physical phenomena and potential applications.",
        "positive": "Critical behavior of diluted magnetic semiconductors: the apparent\n  violation and the eventual restoration of the Harris criterion for all\n  regimes of disorder: Using large-scale Monte Carlo calculations, we consider strongly disordered\nHeisenberg models on a cubic lattice with missing sites (as in diluted magnetic\nsemiconductors such as Ga_{1-x}Mn_{x}As). For disorder ranging from weak to\nstrong levels of dilution, we identify Curie temperatures and calculate the\ncritical exponents nu, gamma, eta, and beta finding, per the Harris criterion,\ngood agreement with critical indices for the pure Heisenberg model where there\nis no disorder component. Moreover, we find that thermodynamic quantities (e.g.\nthe second moment of the magnetization per spin) self average at the\nferromagnetic transition temperature with relative fluctuations tending to zero\nwith increasing system size. We directly calculate effective critical exponents\nfor T > T_{c}, yielding values which may differ significantly from the critical\nindices for the pure system, especially in the presence of strong disorder.\nUltimately, the difference is only apparent, and eventually disappears when T\nis very close to T_{c}."
    },
    {
        "anchor": "Efficient and accurate defect level modelling in monolayer MoS$_2$ via\n  GW+DFT with open boundary conditions: Within the framework of many-body perturbation theory (MBPT) integrated with\ndensity functional theory (DFT), a novel defect-subspace projection GW method,\nthe so-called p-GW, is proposed. By avoiding the periodic defect interference\nthrough open boundary self-energies, we show that the p-GW can efficiently and\naccurately describe quasi-particle correlated defect levels in two-dimensional\n(2D) monolayer MoS$_2$. By comparing two different defect states originating\nfrom sulfur vacancy and adatom to existing theoretical and experimental works,\nwe show that our GW correction to the DFT defect levels is precisely modelled.\nBased on these findings, we expect that our method can provide genuine trap\nstates for various 2D transition-metal dichalcogenide (TMD) monolayers, thus\nenabling the study of defect-induced effects on the device characteristics of\nthese materials via realistic simulations.",
        "positive": "Structure of aluminum atomic chains: First-principles density functional calculations reveal that aluminum can\nform planar chains in zigzag and ladder structures. The most stable one has\nequilateral triangular geometry with four nearest neighbors; the other stable\nzigzag structure has wide bond angle and allows for two nearest neighbors. An\nintermediary structure has the ladder geometry and is formed by two strands.\nAll these planar geometries are, however, more favored energetically than the\nlinear chain. We found that by going from bulk to a chain the character of\nbonding changes and acquires directionality. The conductance of zigzag and\nlinear chains is 4e^2/h under ideal ballistic conditions."
    },
    {
        "anchor": "Surface magnetism in ZnO/Co3O4 mixtures: We recently reported the observation of room temperature ferromagnetism in\nmixtures of ZnO and Co3O4 despite the diamagnetic and antiferromagnetic\ncharacter of these oxides respectively. Here we present a detailed study on the\nelectronic structure of this material in order to account for this unexpected\nferromagnetism. Electrostatic interactions between both oxides lead to a\ndispersion of Co3O4 particles over the surface of ZnO larger ones. As a\nconsequence, the reduction of Co+3 to Co2+ at the particle surface takes place\nas evidenced by XAS measurements and optical spectrocopy. This reduction allows\nto xplain the observed ferromagnetic signal within the well established\ntheories of magnetism.",
        "positive": "sasPDF: pair distribution function analysis of nanoparticle assemblies\n  from small-angle-scattering data: We extends pair distribution function (PDF) analysis into the small-angle\nscattering (SAS) regime and describe the data collection protocol for optimum\ndata quality. We also present the PDFgetS3 software package that can be readily\nused to extract the PDF from small-angle scattering data. We then apply the\nsasPDF method to investigate structures of some representative nanoparticle\nassemblies (NPA) samples with different levels of structural order."
    },
    {
        "anchor": "Examination of computed aluminum grain boundary structures and interface\n  energies that span the 5D space of crystallographic character: The space of possible grain boundary structures is vast, with 5 macroscopic,\ncrystallographic degrees of freedom that define the character of a grain\nboundary. While numerous datasets of grain boundaries have examined this space\nin part or in full, we present a computed dataset of over 7304 unique aluminum\ngrain boundaries in the 5D crystallographic space. Our sampling also includes a\nrange of possible microscopic, atomic configurations for each unique 5D\ncrystallographic structure, which total over 43 million structures. We present\nan overview of the methods used to generate this dataset, an initial\nexamination of the energy trends that follow the Read-Shockley relationship,\nhints at trends throughout the 5D space, variations in GB energy when\nnon-minimum energy structures are examined, and insights gained in machine\nlearning of grain boundary energy structure-property relationships. This\ndataset, which is available for download, has great potential for insight into\nGB structure-property relationships.",
        "positive": "Ferroelectric $\u03c0$-stacks of molecules with the energy gaps in the\n  sunlight range: Ferroelectric $\\pi$-stacked molecular wires for solar cell applications are\ntheoretically designed, in such a way that their energy gaps fall within\nvisible and infrared range of the Sun radiation. Band engineering is tailored\nby a modification of the number of the aromatic rings and via a choice of the\nnumber and kind of the dipole groups. The electronic structures of molecular\nwires and the chemical character of the electron-hole pair are analyzed within\nthe density functional theory (DFT) framework and the hybrid DFT approach by\nmeans of the B3LYP scheme. Moreover, it is found that one of the advantageous\nproperties of these systems - namely the separate-path electron and hole\ntransport - reported earlier, still holds for the larger molecules, due to the\ndipole selection rules for the electron-hole generation, which do not allow the\nlowest optical transitions between the states localized at the same part of the\nmolecule."
    },
    {
        "anchor": "Exchange and correlation effects in the relaxation of hot electrons in\n  noble metals: We report extensive first-principles calculations of the inelastic lifetime\nof low-energy electrons in the noble metals Cu, Ag, and Au. The quasiparticle\nself-energy is computed with full inclusion of exchange and correlation (xc)\neffects, in the framework of the GW\\Gamma approximation of many-body theory.\nAlthough exchange and correlation may considerably reduce both the screening\nand the bare interaction of hot electrons with the Fermi gas, these corrections\nhave opposite signs. Our results indicate that the overall effect of\nshort-range xc is small and GW\\Gamma linewidths are close to their xc-free\nG^0W^0 counterparts, as occurs in the case of a free-electron gas.",
        "positive": "Voltage Dependence of Spin Transfer Torque in Magnetic Tunnel Junctions: Theoretical investigations of spin transfer torque in magnetic tunnel\njunctions using the tight-binding model in the framework of non-equilibrium\nGreen functions formalism are presented. We show that the behavior of the spin\ntransfer torque as a function of applied voltage can vary over a wide range\ndepending on the band parameters of the ferromagnetic electrodes and the\ninsulator that comprise the magnetic tunnel junction. The behavior of both the\nparallel and perpendicular components of the spin torque is addressed. This\nbehavior is explained in terms of the spin and charge current dependence and on\nthe interplay between evanescent states in the insulator and the Fermi surfaces\nof ferromagnetic electrodes comprising the junction. The origin of the\nperpendicular (field-like) component of spin transfer torque at zero bias, i.e.\nexchange coupling through the barrier between ferromagnetic electrodes is\ndiscussed."
    },
    {
        "anchor": "Theory of spin waves in ferromagnetic (Ga,Mn)As: The collective behavior of spins in a dilute magnetic semiconductor is\ndetermined by their mutual interactions and influenced by the underlying\ncrystal structure. Hence, we begin with the atomic quantum-mechanical\ndescription of this system using the proposed variational-perturbation\ncalculus, and then turn to the emerging macroscopic picture employing\nphenomenological constants. Within this framework we study spin waves and\nexchange stiffness in the p-d Zener model of (Ga,Mn)As, its thin layers and\nbulk crystals described by the spds* tight-binding approximation. Analyzing the\nanisotropic part of exchange, we find that the Dzyaloshinskii-Moriya\ninteraction may lead to the cycloidal spin arrangement and uniaxial in-plane\nanisotropy in thin layers, resulting in a surface-like anisotropy in thicker\nfilms. We also derive and discuss the spin-wave contribution to magnetization\nand Curie temperature. Our theory reconstructs the values of stiffness\ndetermined from the temperature dependence of magnetization, but reproduces\nonly partly those obtained from analyzing precession modes in (Ga,Mn)As thin\nfilms.",
        "positive": "Complex electronic structure evolution of NdSb across the magnetic\n  transition: The rare-earth monopnictide (REM) family, which hosts magnetic ground states\nwith extreme magnetoresistance, has established itself as a fruitful playground\nfor the discovery of interesting topological phases. Here, by using\nhigh-resolution angle-resolved photoemission spectroscopy complemented by\nfirst-principles density functional-theory based modeling, we examine the\nevolution of the electronic structure of the candidate REM Dirac semimetal NdSb\nacross the magnetic transition. A complex angel-wing-like band structure near\nthe zone center and three arc-like features at the zone corner have been\nobserved. This dramatic reconstruction of the itinerant bands around the zone\ncenter is shown to be driven by the magnetic transition: Specifically,, the Nd\n5d electron band backfolds at the Gamma point and hybridizes with the Sb 5p\nhole bands in the antiferromagnetic phase. Our study indicates that\nantiferromagnetism plays an intricate role in the electronic structure of the\nREM family."
    },
    {
        "anchor": "Bit storage by $360^\\circ$ domain walls in ferromagnetic nanorings: We propose a design for the magnetic memory cell which allows an efficient\nstorage, recording, and readout of information on the basis of thin film\nferromagnetic nanorings. The information bit is represented by the polarity of\na stable 360$^\\circ$ domain wall introduced into the ring. Switching between\nthe two magnetization states is achieved by the current applied to a wire\npassing through the ring, whereby the $360^\\circ$ domain wall splits into two\ncharged $180^\\circ$ walls, which then move to the opposite extreme of the ring\nto recombine into a $360^\\circ$ wall of the opposite polarity.",
        "positive": "Theoretical study of quantum emitters in two-dimensional silicon carbide\n  monolayer: The features of some potential single-photon sources in two-dimensional\nsilicon carbide monolayers is studied via ab-initio calculation and group\ntheory analysis. A few point defects in three charge states (negative, positive\nand neutral) are considered. By applying performance criteria, Stone-Wales\ndefects without and with combination of antisite defects are studied in\ndetails. The formation energy calculations reveal that neutral and positive\ncharge states of these defects are stable. We compute the zero-phonon-line\nenergy, the Huang-Rhys (HR) factor and the photoluminescence spectrum for the\navailable transitions in different charge states. The calculated HR values and\nthe related Debye-Waller factors guarantee that the Stone-Wales defects have a\nhigh potential of performing as a promising single-photon emitter."
    },
    {
        "anchor": "Suppression of acoustic emission during superelastic tensile cycling of\n  polycrystalline Ni$_{50.4}$Ti$_{49.6}$: We investigate acoustic emission (AE) that arises during the martensitic\ntransition in a polycrystalline specimen of the prototypical\nsuperelastic/elastocaloric alloy Ni$_{50.4}$Ti$_{49.6}$ (at. %) driven using\ntensile strain. We use two independent AE sensors in order to locate AE events,\nand focus on contributions to the AE that arise away from the grips of the\nmechanical testing machine. Significant AE activity is present during the first\nmechanical loading primarily due to nucleation and growth of wide L\\\"uders-like\nbands during the forward martensitic transition (imaged using visible light and\ninfrared (IR) radiation) that lead to persistent changes in intergranular\ninteractions. AE activity is suppressed during the subsequent reverse\nmartensitic transition on unloading, and in successive loading/unloading\ncycles, for which the L\\\"uders-like bands narrow and modify intergranular\ninteractions to much less extent. After the first loading, we find that the AE\nactivity associated with the martensitic transition is weak, and we suggest\nthat this is because the elastic anisotropy and strain incompatibility in Ni-Ti\nare low. We also find that the AE activity becomes weaker on mechanically\ncycling due to increased retained martensite.",
        "positive": "Tunable Magnon-Photon Coupling by Magnon Band Gap in a Layered Hybrid\n  Perovskite Antiferromagnet: Tunability of coherent coupling between fundamental excitations is an\nimportant prerequisite for expanding their functionality in hybrid quantum\nsystems. In hybrid magnonics, the dipolar interaction between magnon and photon\nusually persists and cannot be switched off. Here, we demonstrate this\ncapability by coupling a superconducting resonator to a layered hybrid\nperovskite antiferromagnet, which exhibits a magnon band gap due to its\nintrinsic Dzyaloshinskii-Moriya interaction. The pronounced temperature\nsensitivity of the magnon band gap location allows us to set the photon mode\nwithin the gap and to disable magnon-photon hybridization. When the resonator\nmode falls into the magnon band gap, the resonator damping rate increases due\nto the nonzero coupling to the detuned magnon mode. This phenomena can be used\nto quantify the magnon band gap using an analytical model. Our work brings new\nopportunities in controlling coherent information processing with quantum\nproperties in complex magnetic materials."
    },
    {
        "anchor": "AI-enabled Lorentz microscopy for quantitative imaging of nanoscale\n  magnetic spin textures: The manipulation and control of nanoscale magnetic spin textures is of rising\ninterest as they are potential foundational units in next-generation computing\nparadigms. Achieving this requires a quantitative understanding of the spin\ntexture behavior under external stimuli using in situ experiments. Lorentz\ntransmission electron microscopy (LTEM) enables real-space imaging of spin\ntextures at the nanoscale, but quantitative characterization of in situ data is\nextremely challenging. Here, we present an AI-enabled phase-retrieval method\nbased on integrating a generative deep image prior with an image formation\nforward model for LTEM. Our approach uses a single out-of-focus image for phase\nretrieval and achieves significantly higher accuracy and robustness to noise\ncompared to existing methods. Furthermore, our method is capable of isolating\nsample heterogeneities from magnetic contrast, as shown by application to\nsimulated and experimental data. This approach allows quantitative phase\nreconstruction of in situ data and can also enable near real-time quantitative\nmagnetic imaging.",
        "positive": "Quasiparticle band alignment and stacking-independent exciton in\n  MA$_2$Z$_4$ (M = Mo, W, Ti; A= Si, Ge; Z = N, P, As): Motivated by the recently synthesized two-dimensional semiconducting\nMoSi$_2$N$_4$, we systematically investigate the quasiparticle band alignment\nand exciton in monolayer MA$_2$Z$_4$ (M = Mo, W, Ti; A= Si, Ge; Z = N, P, As)\nusing ab initio GW and Bethe-Salpeter equation calculations. Compared with the\nresults from density functional theory (DFT), our GW calculations reveal\nsubstantially more significant band gaps and different absolute quasiparticle\nenergy but predict the same types of band alignments."
    },
    {
        "anchor": "Strong terahertz radiation via rapid polarization reduction in\n  photoinduced ionic-to-neutral transition of tetrathiafulvalene-p-chloranil: Terahertz lights are usually generated through the optical rectification\nprocess within a femtosecond laser pulse in non-centrosymmetric materials.\nHere, we report a new generation mechanism of terahertz lights based upon a\nphotoinduced phase transition (PIPT), in which an electronic structure is\nrapidly changed by a photoirradiation. When a ferroelectric organic molecular\ncompound, tetrathiafulvalene-p-chloranil, is excited by a femtosecond laser\npulse, the ionic-to-neutral transition is driven and simultaneously a strong\nterahertz radiation is produced. By analyzing the terahertz electric-field\nwaveforms and their dependence on the polarization direction of the incident\nlaser pulse, we demonstrate that the terahertz radiation originates from the\nultrafast decrease of the spontaneous polarization in the photoinduced\nionic-to-neutral transition. The efficiency of the observed terahertz radiation\nvia the PIPT mechanism is found to be much higher than that via the optical\nrectification in the same material and in a typical terahertz emitter, ZnTe.",
        "positive": "Zener Tunneling Breakdown in Phase-Change Materials Revealed by Intense\n  Terahertz Pulses: We have systematically investigated the spatial and temporal dynamics of\ncrystallization that occurs in the phase-change material Ge2Sb2Te5 upon\nirradiation with an intense THz pulse. THz pump and optical probe spectroscopy\nrevealed that Zener tunneling induces a nonlinear increase in the conductivity\nof the crystalline phase. This result indicates that the large electric field\nassociated with the THz pulses causes a nonlinear increase only at the edge of\nthe crystallized area. The electric field concentrating in this area causes a\ntemperature increase via Joule heating, which in turn leads to nanometer scale\ncrystal growth parallel to the field and the formation of filamentary\nconductive domains across the sample."
    },
    {
        "anchor": "Manipulating the anisotropic phase separation in strained VO2 epitaxial\n  films by nanoscale ion-implantation: Manipulating the strain induced poly-domains and phase transition in\ncorrelated oxide material are important for high performance devices\nfabrication. Though the electronic transport in the strained oxide film at\nmacroscopic scales can be directly measured, the anisotropic electronic state\nand the controllable phase separation cross the insulator-to-metal transition\nwithin nanoscale size are still elusive. Here, we selected VO2 crystal film as\na prototypical oxide and achieved the manipulation of anisotropy electronic\nphase separation via injecting He+ nanobeam into VO2 film at room temperature.\nIn addition, this nanoscale phase separation was directly visualized by\ninfrared near-field imaging measurements, showing the pronounced and unique\ncR-axis dependent anisotropy on VO2 surface. Our results offered new insights\ntowards understanding the anisotropic nanoscale phase separation in strained\nmetal oxide films.",
        "positive": "Direct determination of the zero-field splitting for Fe$^{3+}$ ion in a\n  synthetic polymorph of the oxalate mineral stepanovite\n  NaMgFe(C$_2$O$_4$)$_3\\cdot$9H$_2$O: a natural MOF: We employed inelastic neutron scattering (INS), specific heat, and\nmagnetization analysis to study the magnetism in a synthetic polymorph of the\nquasi-two-dimensional natural metal-organic framework material, stepanovite\nNaMgFe(C$_2$O$_4$)$_3\\cdot$9H$_2$O. No long-range magnetic order can be\nobserved down to 0.5 K. The INS spectra show two dispersionless excitations at\nenergy transfer 0.028(1) and 0.050(1) meV at base temperature, which are\nderived from the magnetic transitions between zero-field splitting (ZFS) of $S$\n= 5/2 ground state multiplets of Fe$^{3+}$ ion. Further analysis of the INS\nresults shows that the Fe$^{3+}$ ion has an easy-axis anisotropy with axial ZFS\nparameter $D$ = $-$0.0128(5) meV and rhombic parameter $E$ = 0.0014(5) meV. The\nupward behavior at zero field and Schottky-like peak under magnetic field of\nthe low-temperature magnetic specific heat further support the INS results. Our\nresults clearly reveal the magnetic ground and excited state of this\nstepanovite polymorph."
    },
    {
        "anchor": "Structural and electrochemical properties of MnO2-Carbon based\n  supercapacitor electrodes: We present results of an approach to incorporate redox-active manganese oxide\ninto the 3-dimensional porous structure of carbon xerogels under self-limiting\nelectroless conditions. By varying the structure of the carbon backbone, we\nfound that deposition of manganese oxide preferably takes place on the external\nsurface area of the carbon xerogels. From our detailed analysis we conclude\nthat 3-dimensional carbon xerogels with particle and pore sizes ranging from 10\nto 20 nm and low manganese oxide precursor concentration combined with long\ndeposition times are beneficial for fast operating pseudocapacitance electrodes\nwith high capacitance and effective use of the redox active component.",
        "positive": "Hydrogenated Bilayer Wurtzite SiC Nanofilms: A Two-Dimensional Bipolar\n  Magnetic Semiconductor Material: Recently, a new kind of spintronics materials, bipolar magnetic semiconductor\n(BMS), has been proposed. The spin polarization of BMS can be conveniently\ncontrolled by a gate voltage, which makes it very attractive in device\nengineering. Now, the main challenge is finding more BMS materials. In this\narticle, we propose that hydrogenated wurtzite SiC nanofilm is a\ntwo-dimensional BMS material. Its BMS character is very robust under the effect\nof strain, substrate, or even a strong electric field. The proposed\ntwo-dimensional BMS material paves the way to use this promising new material\nin an integrated circuit."
    },
    {
        "anchor": "Symmetry Lowering Through Surface Engineering and Improved\n  Thermoelectric Properties in MXenes: Despite ample evidence of their influences on the transport properties of\ntwo-dimensional solids, the interrelations of reduced symmetry, electronic and\nthermal transport, have rarely being discussed in the context of thermoelectric\nmaterials. With the motivation to design new thermoelectric materials with\nimproved properties, we have addressed these by performing first-principles\nDensity Functional Theory based calculations in conjunction with semi-classical\nBoltzmann transport theory on a number of compounds in the MXene family. The\nsymmetry lowering in parent M$_{2}$CO$_{2}$ MXenes are done by replacing\ntransition metal $M$ on one surface, resulting in Janus compounds\nMM$^{\\prime}$CO$_{2}$. Our calculations show that the thermoelectric\nfigure-of-merit can be improved significantly by such surface engineering. We\ndiscuss in detail, both qualitatively and quantitatively, the origin behind\nhigh thermoelectric parameters for these compounds. Our in-depth analysis shows\nthat the modifications in the electronic band structures and degree of\nanharmonicity driven by the dispersions in the bond strengths due to lowering\nof symmetry, an artefact of surface engineering, are the factors behind the\ntrends in the thermoelectric parameters of the MXenes considered. The results\nalso substantiate that the compositional flexibility offered by the MXene\nfamily of compounds can generate complex interplay of symmetry, electronic\nstructure, bond strengths and anharmonicity which can be exploited to engineer\nthermoelectric materials with improved properties.",
        "positive": "Effect of He-ion irradiation on Fe-Cr alloys: M\u00f6ssbauer - effect study: Effect of He ion irradiation on three model Fe(100-x)Cr(x) alloys (x =5.8,\n10.75 and 15.15) was investigated with the conversion electron M\\\"ossbauer\nspectroscopy. The study of the alloys irradiated with 25 keV ions revealed that\nthe strongest effect occured in the Fe(84.85)Cr(15.15) sample where an\ninversion of a short-range-order (SRO) parameter was found. Consequently, the\ninvestigation of the influence of the irradiation dose, D, was carried out on\nthe chromium-most concentrated sample showing that the average hyperfine field,\n<B>, the average angle between the normal to the sample's surface and the\nmagnetization vector, <theta>, as well as the actual distribution of Fe/Cr\natoms, as expressed by SRO parameters, strongly depend on D. In particular: (a)\n<B> increases with D, and its maximum increase corresponds to a decrease of Cr\ncontent within the two-shell volume around the probe 57Fe nuclei by ~2.3 at%,\n<theta> decreases by ~13 degree at maximum, (c) SRO-parameter averaged over the\ntwo-shell volume increases with D from weakly negative value (indicative of Cr\natoms clustering) to weakly positive value (indicative of Cr atoms ordering).\nThe inversion takes place at D ca. 7 dpa."
    },
    {
        "anchor": "Role of disorder in the size-scaling of material strength: We study the sample size dependence of the strength of disordered materials\nwith a flaw, by numerical simulations of lattice models for fracture. We find a\ncrossover between a regime controlled by the fluctuations due to disorder and\nanother controlled by stress-concentrations, ruled by continuum fracture\nmechanics. The results are formulated in terms of a scaling law involving a\nstatistical fracture process zone. Its existence and scaling properties are\nonly revealed by sampling over many configurations of the disorder. The scaling\nlaw is in good agreement with experimental results obtained from notched paper\nsamples.",
        "positive": "Hartree-Fock Studies of the Ferroelectric Perovskites: Within an ab-initio HF scheme, we use both Berry-phase calculations and\nsupercell calculations in order to compute the dynamical charges for lattice\ndynamics and the electronic dielectric constant for KNbO_3 and BaTiO_3.\nComparison with experimental data indicates that HF provides a description of\nthe electronic properties of this material whose accuracy is of the same order\nas the LDA one. There are however significant differences between the two sets\nof results, whose origin is scrutinized. Motivated by the study of surface and\ndomain-boundary properties, we also present some results for BaTiO_3 slabs,\nincluding both genuinely isolated and periodically repeated slabs with\ndifferent terminations. The capability of dealing with a genuinely isolated\nslab is a virtue of the localized-basis implementation adopted here. We\ndemonstrate, amongst other things, the nontrivial dynamical-charge neutrality\nof BaTiO_3 [001] surfaces."
    },
    {
        "anchor": "Generation of basis vectors for magnetic structures and displacement\n  modes: Increasing attention is being focussed on the use of symmetry-adapted\nfunctions to describe magnetic structures, structural distortions, and\nincommensurate crystallography. Though the calculation of such functions is\nwell developed, significant difficulties can arise, such as the generation of\ntoo many or too few basis functions to minimally span the linear vector space.\nWe present an elegant solution to these difficulties using the concept of basis\nsets, and discuss previous work in this area using this concept. Further, we\nhighlight the significance of unitary irreducible representations in this\nmethod, and provide the first validation that the irreducible representations\nof the crystallographic space groups tabulated by Kovalev are unitary",
        "positive": "The Role of Density Functional Theory Methods in the Prediction of\n  Nanostructured Gas-Adsorbent Materials: With the advent of new synthesis and large-scale production technologies,\nnanostructured gas-adsorbent materials (GAM) like carbon nanocomposites and\nmetal-organic frameworks are becoming increasingly more influential in our\neveryday lives. First-principles methods based on density functional theory\n(DFT) have been pivotal in establishing the rational design of GAM, a factor\nwhich has tremendously boosted their development. However, DFT methods are not\nperfect and due to the stringent accuracy thresholds demanded in modelling of\nGAM (i.e., exact binding energies to within ~0.01 eV) these techniques may\nprovide erroneous conclusions in some challenging situations. Examples of\nproblematic circumstances include gas-adsorption processes in which both\nelectronic long-range exchange and nonlocal correlations are important, and\nsystems where many-body energy and Coulomb screening effects cannot be\ndisregarded. In this critical review, we analyse recent efforts done in the\nassessment of the performance of DFT methods in the prediction and\nunderstanding of GAM. Our inquiry is constrained to the areas of hydrogen\nstorage and carbon capture and sequestration, for which we expose a number of\nunresolved modelling controversies and define a set of best practice simulation\nprinciples. Also, we identify the subtle problems found in the generalization\nof DFT benchmark studies performed in model cluster systems to real materials,\nand discuss effective approaches to circumvent them. The increasing awareness\nof the strengths and imperfections of DFT methods in the simulation of\ngas-adsorption phenomena should lead in the medium term to more precise, and\nhence even more fruitful, ab initio engineering of GAM."
    },
    {
        "anchor": "First-principles investigation of organic photovoltaic materials\n  C$_{60}$, C$_{70}$, [C$_{60}$]PCBM, and bis-[C$_{60}$]PCBM using a many-body\n  $G_0W_0$-Lanczos approach: We present a first-principles investigation of the excited-state properties\nof electron acceptors in organic photovoltaics including C$_{60}$, C$_{70}$,\n[6,6]-phenyl-C$_{61}$-butyric-acid-methyl-ester ([C$_{60}$]PCBM), and\nbis-[C$_{60}$]PCBM using many-body perturbation theory within the Hedin's\n$G_0W_0$ approximation and an efficient Lanczos approach. Calculated vertical\nionization potentials (VIP) and vertical electron affinities (VEA) of C$_{60}$\nand C$_{70}$ agree very well with experimental values measured in gas phase.\nThe density of states of all three molecules is also compared to photoemission\nand inverse photoemission spectra measured on thin-films, exhibiting a close\nagreement - a rigid energy-gap renormalization owing to intermolecular\ninteractions in the thin-films. In addition, it is shown that the low-lying\nunoccupied states of [C$_{60}$]PCBM are all derived from the highest-occupied\nmolecular orbitals and the lowest-unoccupied molecular orbitals of fullerene\nC$_{60}$. The functional side group in [C$_{60}$]PCBM introduces a slight\nelectron transfer to the fullerene cage, resulting in small decreases of both\nVIP and VEA. This small change of VEA provides a solid justification for the\nincrease of open-circuit voltage when replacing fullerene C$_{60}$ with\n[C$_{60}$]PCBM as the electron acceptor in bulk heterojunction polymer solar\ncells.",
        "positive": "Effects of epitaxial strain and ordering direction on the electronic\n  properties of (GaSb)_1/(InSb)_1 and (InAs)_1/(InSb)_1 superlattices: The structural and electronic properties in common anion (GaSb)_1/(InSb)_1\nand common cation (InAs)_1/(InSb)_1 [111] ordered superlattices have been\ndetermined using the local density total energy full potential linearized\naugmented plane wave method. The influence of the ordering direction, strain\nconditions and atomic substitution on the electronic properties of\ntechnological and experimental interest (such as energy band-gaps and charge\ncarrier localization in the different sublattices) were determined. The results\nshow an appreciable energy band-gap narrowing compared to the band-gap averaged\nover the constituent binaries, either in [001] ordered structures or (more\nmarkedly) in the [111] systems; moreover energy band-gaps show an increasing\ntrend as the substrate lattice parameter is decreased. Finally, the systems\nexamined offer interesting opportunities for band-gap tuning as a function of\nthe growth condition (about 0.7 eV in (GaSb)_1/(InSb)_1 and 0.3 eV in\n(InAs)_1/(InSb)_1)."
    },
    {
        "anchor": "Universal Limits of Thermopower and Figure of Merit from Transport\n  Energy Statistics: The search for new thermoelectric materials aims at improving their power and\nefficiency, as expressed by thermopower $S$ and figure of merit $ZT$. By\nconsidering a very general transport spectral function $W(E)$, expressions for\n$S$ and $ZT$ can be derived, which contain the statistical weights of an\neffective distribution function only, see Refs.\n\\cite{eltschka16,mahan96,matveev00}.\n  We assumption of a Lorentzian shape with width $k_BT$ resulting from the\nelectron-phonon coupling allows to estimate an upper limit of $S$ and $ZT$\nindependent on the microscopic mechanisms of the transport process. A simple\nestimate for an upper limit of the thermopwer $S$ is derived from {} formula.\nIt is given by 3 times the unit of the thermopower $k_b/e$ which is about\n250~$\\mu V/K$.\n  We consider different systems which represent the general features of the\nelectronic structure of thermoelectric relevant materials very well. The\ntransport integrals were evaluated varying the band gap size and the chemical\npotential position. For all cases upper limits for both, the thermopower and\nthe figure of merit, are obtained. The universal limit of $|S|$ is given by\n1.88 in units of $k_B/e$, which is about 160~$\\mu V/K$. The universal limit for\n$ZT$ is obtained by about 1.11, which is in good agreement with available\nthermoelectric systems and devices.",
        "positive": "Photo-induced Hidden Phase of 1T-TaS2 with Tunable Lifetime: Phase transitions are ubiquitous, appearing at every length scale from atoms\nto galaxies. In condensed matter, ultrafast laser pulses drive materials to\nhighly non-equilibrium conditions allowing transitions to new phases of matter\nnot attainable under thermal excitation. Despite the intense scrutiny these\nhidden phases have received, the details of the dynamics of transition and\nreestablishment of the ground state remain largely unexplored. Here, we show\nthe transition to a hidden phase of 1T-TaS2 driven by the screening of\nCoulombic repulsive interaction by photoexcited electrons. The temporal\nevolution of the coherent lattice dynamics highlights the existence of a novel\nphase with a laser fluence-dependent lifetime. The modeling of the dynamics\nreveals that the transition is caused by photo-excited carriers and it\ndisappears at the rate of electron-phonon scattering. Our results demonstrate\nhow femtosecond laser absorption leads to a decoupling of the electronic and\nlattice sub-systems, opening the way to novel states of matter, which can be\ncontrolled with light. We expect our investigation to be a starting point\ntowards the development of novel ultrafast photonics devices, such as switches\nand modulators, taking advantage of fast and tunable phase transitions."
    },
    {
        "anchor": "Disorder-Induced Complex Magnetization Dynamics in Planar Ensembles of\n  Nanoparticles: The magnetic relaxation characteristics are investigated in the\ntwo-dimensional ($l^{}_x\\times l^{}_y$) assembly of nanoparticles as a function\nof out-of-plane positional disorder strength $\\Delta(\\%)$ using numerical\nsimulations. Such defects are redundantly observed in experimentally fabricated\nnanostructures, resulting in unusual magnetization dynamics. The magnetization\ndecays exponentially for small and negligible dipolar interaction strength\n$h^{}_d\\leq0.2$. In such a case, the magnetization relaxation does not depend\non $\\Delta$ and aspect ratio $A^{}_r=l^{}_y/l^{}_x$, as expected. In\nsquare-like MNPs ensembles and perfectly ordered system ($\\Delta(\\%)=0$), the\nmagnetization relaxes rapidly with an increase in $h^{}_d$. Consequently, the\neffective N\\'eel relaxation time $\\tau^{}_N$ decreases with $h^{}_d$. The\ndipolar interaction of sufficient strength promotes antiferromagnetic coupling\nin such a system, resulting in rapid magnetization decay. Remarkably, the\nout-of-plane disorder instigates the magnetic moment to interact\nferromagnetically in the presence of large $h^{}_d$, even in the square-like\nassembly of MNPs. As a result, magnetization relaxation slows down, resulting\nin a monotonous increase of $\\tau^{}_N$ with an increase in $\\Delta$ and\n$h^{}_d$ in such cases. Notably, there is a prolonged magnetization decay in\nthe highly anisotropic system with large $h^{}_d$. The dipolar interaction\ninduces ferromagnetic coupling along the long axis of the system in such cases.\nTherefore, the magnetization ceases to relax as a function of time for large\n$h^{}_d$, irrespective of disorder strength $\\Delta(\\%)$. The present work\ncould provide a concrete theoretical basis to explain the unexpected relaxation\nbehaviour observed in experiments. These results are also beneficial in digital\ndata storage and spintronics based applications where such nanostructures are\nextensively used.",
        "positive": "Study of Phase Stability in NiPt Systems: We have studied the problem of phase stability in NiPt alloy system. We have\nused the augmented space recursion based on the TB-LMTO as the method for\nstudying the electronic structure of the alloys. In particular, we have used\nthe relativistic generalization of our earlier technique. We note that, in\norder to predict the proper ground state structures and energetics, in addition\nto relativistic effects, we have to take into account charge transfer effects\nwith precision."
    },
    {
        "anchor": "Cooperatively Modulating Magnetic Anisotropy and Colossal\n  Magnetoresistance via Atomic-Scale Buffer Layers in Highly Strained\n  La0.7Sr0.3MnO3 Films: Simultaneous control of magnetic anisotropy and magnetoresistance, especially\nwith atomic scale precision, remains a pivotal challenge for realizing advanced\nspintronic functionalities. Here we demonstrate cooperative continuous control\nover both magnetoresistance and magnetic anisotropy in highly strained\nLa0.7Sr0.3MnO3 (LSMO) thin films. By inserting varying perovskite buffer\nlayers, compressively strained LSMO films transition from a ferromagnetic\ninsulator with out-of-plane magnetic anisotropy to a metallic state with\nin-plane anisotropy. Atomic-scale buffer layer insertion enables remarkably\nacute, precise control to sharply modulate this magnetic phase transformation.\nA gigantic 10,000% modulation of the colossal magnetoresistance (CMR) and an\nexceptionally sharp transition from out-of-plane to in-plane magnetic\nanisotropy are attained in just a few contiguous layers. These atomic-scale\ncorrelations among electronic, magnetic, and structural order parameters yield\nflexible multifunctional control promising for next-generation oxide\nspintronics.",
        "positive": "A multiferroic two-dimensional electron gas: Multiferroics are compounds in which at least two ferroic orders coexist -\ntypically (anti)ferromagnetism and ferroelectricity. While magnetic order can\narise in both insulating and conducting compounds, ferroelectricity is in\nprinciple not allowed in metals although a few two-dimensional (semi)metals\nwere reported to behave as ferroelectrics. Yet, the combination with magnetic\norder to realize multiferroic metals remains elusive. Here, by combining x-ray\nspectroscopy and magnetotransport, we show the coexistence of ferroelectricity\nand magnetism in an oxide-based two-dimensional electron gas (2DEG). The data\nevidence a non-volatile switching of the polar displacements and of the\nanomalous Hall effect by the polarization direction, demonstrating a\nmagnetoelectric coupling. Our findings provide new opportunities in quantum\nmatter stemming from the interplay between ferroelectricity, ferromagnetism and\nRashba spin-orbit coupling in a 2DEG."
    },
    {
        "anchor": "Flatten the Li-ion Activation in Perfectly Lattice-matched MXene and\n  1T-MoS2 Heterostructures via Chemical Functionalization: MXene and its derivatives have attracted considerable attention for potential\napplication in energy storage like batteries and supercapacitors owing to its\nultrathin metallic structures. However, the complexity of the ionic and\nelectronic dynamics in MXene based hybrids, which are normally needed for\ndevice integration, triggers both challenges and opportunities for its\napplication. In this paper, as a prototype of metallic hybrids of MXene,\nheterostructures consisting of Ti3C2T2 (T= None, O and F atoms) and metallic\nMoS2 (1T phase) are investigated. Through density functional theory, we\ninvestigate the interfacial electronic variation, thermal activation, and anode\nperformance in the lithium-ion battery (LIB) of Ti3C2T2/1T-MoS2. We found that\ndifferent surface atomic groups in MXene can significantly alter the affinity,\nredox reaction and kinetics of Li atoms in the interface of the Ti3C2T2 and\n1T-MoS2. Through examining the three possible pathways of Li by climbing\nimage-nudged elastic band (CI-NEB) and ab-initio molecular dynamics (AIMD)\nsimulation, the diffusion curve becomes significantly flattened from the naked\nto O- and F-terminated Ti3C2 MXene with activation barriers reducing from 0.80\nto 0.22 and 0.29 eV, respectively, and room-temperature diffusion coefficients\nincreasing from 1.20x10-6 to 2.75x10-6, 1.70x10-4 cm2 s-1, respectively. The\nfunctionalization with O or F eliminates the steric hindrance of Li\nintercalation by breaking the strong interaction between two layers and\nprovides additional adsorption sites for Li diffusion in the meantime. Our work\nsuggests that surface functional groups play a significant role in\nTi3C2T2/1T-MoS2 modification and Ti3C2F2/1T-MoS2 with the high diffusion\ncoefficient and theoretical capacity could be a promising anode material for\nLIBs.",
        "positive": "Two-Dimensional Quantum Dynamics of O$_2$ Dissociative Adsorption on\n  Ag(111): We have investigated the quantum dynamics of O2 dissociative adsorption on a\nAg(111) surface. We performed the calculations with a Hamiltonian where the O2\ntranslational motion is perpendicular to the surface and for O2 vibrational\nenergy. We found that dissociative adsorption occurs with an incident\ntranslational energy below the expected activation barrier, while the\ntranslational-energy dependence for adsorption probabilities is a smooth\nsigmoid. Thus, there are non-negligible tunneling effects in the dissociative\nadsorption that are affected by the activation barrier width. Moreover, the\nincident translational energies at the inflection points of the adsorption\nprobabilities shift lower with increasing in vibrational quantum numbers of the\nincident O2. Thus, there is significant energy transfer and coupling from\nvibration to translational motion. The vibrational energy assists the O2\ndissociative adsorption via a vibrationally assisted sticking effect."
    },
    {
        "anchor": "Phase-Field Modeling of Solidification in Light-Metal Matrix\n  Nanocomposites: The quantitative phase-field approach has been adapted to model\nsolidification in the presence of Metal Matrix Nanocomposites (MMNCs) in a\nsingle-component liquid. Nanoparticles of fixed size and shape are represented\nby additional fields. The corresponding equations of motion are assumed to\nensure relaxation dynamics, and can be supplemented by random forces (realizing\nBrownian motion) or external fields. The nanoparticles are characterized by two\nmodel parameters: their mobility and the contact angle they realize with the\nsolid-liquid interface. We investigate the question how grain size distribution\ncan be influenced by heterogeneous nucleation on the nanoparticles and by the\nfront-particle interaction. We explore, furthermore, how materials and process\nparameters, such as temperature, density and size/shape distribution of the\nnanoparticles, influence microstructure evolution.",
        "positive": "A model for the dynamics and internal structure of planar doping fronts\n  in organic semiconductors: The dynamics and internal structure of doping fronts in organic\nsemiconductors are investigated theoretically using an extended drift-diffusion\nmodel for ions, electrons and holes. The model also involves the injection\nbarriers for electrons and holes in the partially doped regions in the form of\nthe Nernst equation, together with a strong dependence of the electron and hole\nmobility on concentrations. Closed expressions for the front velocities and the\nion concentrations in the doped regions are obtained. The analytical theory is\nemployed to describe the acceleration of the p- and n-fronts towards each\nother. The analytical results show very good agreement with the experimental\ndata. Furthermore, it is shown that the internal structure of the doping fronts\nis determined by the diffusion and mobility processes. The asymptotic behavior\nof the concentrations and the electric field is studied analytically inside the\ndoping fronts. The numerical solution for the front structure confirms the most\nimportant predictions of the analytical theory: a sharp head of the front in\nthe undoped region, a smooth relaxation tail in the doped region, and a plateau\nat the critical point of transition from doped to undoped regions."
    },
    {
        "anchor": "The Li intercalation potential of LiMPO4 and LiMSiO4 olivines with M =\n  Fe, Mn, Co, Ni: The Li intercalation potential of LiMPO4 and LiMSiO4 compounds with M = Fe,\nMn, Co, and Ni is computed with the GGA+U method. It is found that this\napproach is considerably more accurate than standard LDA or GGA methods. The\ncalculated potentials for LiFePO4, LiMnPO4 and LiCoOPO4 agree to within 0.1 V\nwith experimental results. The LiNiPO4 potential is predicted to be above 5 V.\nThe potentials of the silicate materials are all found to be rather high, but\nLiFeSiO4 and LiCoSiO4 have negligible volume change upon Li extraction.",
        "positive": "Observation of the magnetic domain structures in Cu$_{0,47}$Ni$_{0,53}$\n  thin films at low temperatures: We report on the first experimental visualization of domain structure in\nfilms of weakly ferromagnetic Cu$_{0,47}$Ni$_{0,53}$ alloy with different\nthickness at liquid helium temperatures. Improved high-resolution Bitter\ndecoration technique was used to map the magnetic contrast on the top of the\nfilms well below the Curie temperature T$_{Curie}$ ($\\sim$ 60 K). In contrast\nto magnetic force microscopy, this technique allowed visualization of the\ndomain structure without its disturbance while the larger areas of the sample\nwere probed. Maze-like domain patterns, typical for perpendicular magnetic\nanisotropy, were observed. The average domain width was found to be about 100\nnm."
    },
    {
        "anchor": "Time-Resolved Spectroscopy of Single Excitons Bound to Pairs of Te\n  Isoelectronic Impurity Centers in ZnSe: Tellurium impurity centers in ZnSe were individually probed with\ntime-resolved photoluminescence (PL) spectroscopy. Resolution-limited peaks\nwith an ultra-low spatial density originate in the recombination of excitons\ndeeply bound to isolated nearest-neighbor isoelectronic Te pairs (Te2). This\ninterpretation is confirmed by ab-initio calculations. The peaks reveal\nanti-bunched photon emission and a doublet structure polarized along [110] and\n[-110]. We analyze the time-resolved PL decay to clarify the role of the dark\nstates in the spin relaxation and radiative recombination of single\nfine-structure split excitons.",
        "positive": "Effects of Multi-Surface Modification on Curie temperature of\n  ferroelectric films: Within the framework of mean field theory, we study the effects of\nmulti-surface modification on Curie temperature of ferroelectric films using\nthe transverse Ising model. The general nonlinear equations for Curie\ntemperature of multi-surface ferroelectric films with arbitrary exchange\nconstants and transverse fields are derived by the transfer matrix method. As\nan example, we consider a film consisting of top surface layers, bulk layers\nand bottom surface layers. Two types of surface modifications, modifications of\na surface exchange constant and a surface transverse field are taken into\naccount. The dependence of Curie temperature on the surface layer numbers, bulk\nlayer numbers, surface exchange constants, surface transverse fields and bulk\ntransverse fields is discussed."
    },
    {
        "anchor": "Native surface oxide turns alloyed silicon membranes into nanophononic\n  metamaterials with ultra-low thermal conductivity: A detailed understanding of the relation between microscopic structure and\nphonon propagation at the nan oscale is essential to design materials with\ndesired phononic and thermal properties.Here we uncover a new mechanism of\nphonon interaction in surface oxidized membranes, i.e., native oxide layers\ninteract with phonons in ultra-thin silicon membranes through local resonances.\nThe local resonances reduce the low frequency phonon group velocities and\nshorten their mean free path. This effect opens up a new strategy for ultralow\nthermal conductivity design as it complements the scattering mechanism which\nscatters higher frequency modes effectively. The combination of native oxide\nlayer and alloying with germanium in concentration as small as 5% reduces the\nthermal conductivity of silicon membranes to 100 time lower than the bulk. In\naddition, the resonance mechanism produced by native oxide surface layers is\nparticularly effective for thermal condutivity reduction even at very low\ntemperatures, at which only low frequency modes are populated.",
        "positive": "Ferromagnetism and interlayer exchange coupling in short period\n  (Ga,Mn)As/GaAs superlattices: Magnetic properties of (Ga,Mn)As/GaAs superlattices are investigated. The\nstructures contain magnetic (Ga,Mn)As layers, separated by thin layers of\nnon-magnetic GaAs spacer. The short period Ga$_{0.93}$Mn$_{0.07}$As/GaAs\nsuperlattices exhibit a paramagnetic-to-ferromagnetic phase transition close to\n60K, for thicknesses of (Ga,Mn)As down to 23 \\AA. For\nGa$_{0.96}$Mn$_{0.04}$As/GaAs superlattices of similar dimensions, the Curie\ntemperature associated with the ferromagnetic transition is found to oscillate\nwith the thickness of non magnetic spacer. The observed oscillations are\nrelated to an interlayer exchange interaction mediated by the polarized holes\nof the (Ga,Mn)As layers."
    },
    {
        "anchor": "Fundamentals in generalized elasticity and dislocation theory of\n  quasicrystals: Green tensor, dislocation key-formulas and dislocation loops: The present work provides fundamental quantities in generalized elasticity\nand dislocation theory of quasicrystals. In a clear and straightforward manner,\nthe three-dimensional Green tensor of generalized elasticity theory and the\nextended displacement vector for an arbitrary extended force are derived. Next,\nin the framework of dislocation theory of quasicrystals, the solutions of the\nfield equations for the extended displacement vector and the extended elastic\ndistortion tensor are given; that is the generalized Burgers equation for\narbitrary sources and the generalized Mura-Willis formula, respectively.\nMoreover, important quantities of the theory of dislocations as the Eshelby\nstress tensor, Peach-Koehler force, stress function tensor and the interaction\nenergy are derived for general dislocations. The application to dislocation\nloops gives rise to the generalized Burgers equation, where the displacement\nvector can be written as a sum of a line integral plus a purely geometric part.\nFinally, using the Green tensor, all other dislocation key-formulas for loops,\nknown from the theory of anisotropic elasticity, like the Peach-Koehler stress\nformula, Mura-Willis equation, Volterra equation, stress function tensor and\nthe interaction energy are derived for quasicrystals.",
        "positive": "Modeling lithium-ion solid-state electrolytes with a pinball model: We introduce a simple and efficient model to describe the potential energy\nsurface of lithium diffusing in a solid-state ionic conductor. First, we assume\nthat the Li atoms are fully ionized and we neglect the weak dependence of the\nelectronic valence charge density on the instantaneous position of the Li ions.\nSecond, we freeze the atoms of the host lattice in their equilibrium positions;\nconsequently, also the valence charge density is frozen. We thus obtain a\ncomputational setup (the \"pinball model\") for which extremely inexpensive\nmolecular dynamics simulation can be performed. To assess the accuracy of the\nmodel, we contrast it with full first-principles molecular dynamics simulations\nperformed either with a free or frozen host lattice; in this latter case, the\ncharge density still readjusts itself self-consistently to the actual positions\nof the diffusing Li ions. We show that the pinball model is able to reproduce\naccurately the static and dynamic properties of the diffusing Li ions -\nincluding forces, power spectra, and diffusion coefficients - when compared to\nthe self-consistent frozen-host lattice simulations. The frozen-lattice\napproximation itself is often accurate enough, and certainly a good proxy in\nmost materials. These observations unlock efficient ways to simulating the\ndiffusion of lithium in the solid state, and provide additional physical\ninsight into the respective roles of charge-density rearrangements or lattice\nvibrations in affecting lithium diffusion."
    },
    {
        "anchor": "The Validity Window of Space-Charge-Limited Current Measurements of\n  Metal Halide Perovskite Devices: Space-charge-limited current (SCLC) measurements are used to estimate charge\ncarrier mobilities and electronic trap densities of semiconductors by analysing\nthe current density-voltage (JV) relationship for unipolar devices predicted by\nthe Mott-Gurney (MG) law. However, the interpretation of SCLC measurements for\nmetal-halide perovskites is problematic due to mobile ionic defects which\nredistribute to screen electrostatic fields in devices during measurements. To\novercome this, an SCLC measurement protocol was recently suggested that\nminimises ionic charge redistribution by probing the current during millisecond\nvoltage pulses superimposed on a background bias. Here, we use drift-diffusion\nsimulations with mobile ions to assess the validity of the MG law for analysing\nboth the standard and new protocol JV measurements. We simulated idealised\nperovskite devices with differing mobile ion densities and compared them with\nsimulations and measurements of devices with typical contact materials. We\nfound the validity region for the MG law is limited to perovskites with mobile\nion densities lower than the device's equilibrium charge carrier density\n(<10^17 cm-3 for 400 nm thick methylammonium lead iodide films) and contacts\nwith injection/extraction barriers <=0.1 eV. The latter limitation can be\npartially overcome by increasing the device thickness, whereas the former\nlimitation cannot. This restricts the range of perovskite layer compositions\nand viable contact materials that can be reliably analysed with the MG law.\nApproaches such as estimating trap densities from the apparent voltage onset to\ntrap-free SCLC regime should also be critically reviewed since they rely on the\nsame potentially invalid assumptions as the MG law. Our results demonstrate\nthat extracting meaningful and accurate values for metal halide perovskite\nmaterial properties from SCLC maybe challenging, or often not possible.",
        "positive": "Atom motion in solids following nuclear transmutation: Following nuclear decay, a daughter atom in a solid will \"stay in place\" if\nthe recoil energy is less than the threshold for displacement. At high\ntemperature, it may subsequently undergo long-range diffusion or some other\nkind of atomic motion. In this paper, motion of 111Cd tracer probe atoms is\nreconsidered following electron-capture decay of 111In in the series of In3R\nphases (R= rare-earth). The motion produces nuclear relaxation that was\nmeasured using the method of perturbed angular correlation. Previous\nmeasurements along the entire series of In3R phases appeared to show a\ncrossover between two diffusional regimes. While relaxation for R= Lu-Tb is\nconsistent with a simple vacancy diffusion mechanism, relaxation for R= Nd-La\nis not. More recent measurements in Pd3R phases demonstrate that the\nsite-preference of the parent In-probe changes along the series and suggests\nthat the same behavior occurs for daughter Cd-probes. The anomalous motion\nobserved for R= Nd-La is attributed to \"lanthanide expansion\" occurring towards\nLa end-member phases. For In3La, the Cd-tracer is found to jump away from its\noriginal location on the In-sublattice in an extremely short time, of order 0.5\nns at 1000 K and 1.2 ms at room temperature, a residence time too short to be\nconsistent with defect-mediated diffusion. Several scenarios that can explain\nthe relaxation are presented based on the hypothesis that daughter Cd-probes\nfirst jump to neighboring interstitial sites and then are either trapped and\nimmobilized, undergo long-range diffusion, or persist in a localized motion in\na cage."
    },
    {
        "anchor": "Enhancing the magnetoelectric coupling of Co4Nb2O9[100] by substitution\n  of Mg for Co: We report experimental studies on enhancing the magnetoelectric (ME) coupling\nof Co$_4$Nb$_2$O$_9$ by substitution of non-magnetic metal Mg for Co. A series\nof single crystal Co$_{4-x}$Mg$_x$Nb$_2$O$_9$ (x=0, 1, 2, 3) with a\nsingle-phase corundum-type structure are synthesized by the optical floating\nzone method, and the good quality and crystallographic orientations of the\nsynthesized samples are confirmed by Laue spots and sharp XRD peaks. Although\nthe Neel temperature ($T_N$) of the Mg substituted crystals are slightly\ndecreased from 27 K for pure Co$_4$Nb$_2$O$_9$ to 19 K and 11 K for\nCo$_3$MgNb$_2$O$_9$ and Co$_2$Mg$_2$Nb$_2$O$_9$, respectively, the ME coupling\nis double enhanced by Mg substitution when x=1. For the magnetic field\n(electric field) control of electric polarization (magnetization), the ME\ncoefficient $\\alpha_{ME}$ of Co$_3$MgNb$_2$O$_9$ is measured to be 12.8 ps/m\n(13.7 ps/m). These results indicate that the Mg substituted\nCo$_{4-x}$Mg$_x$Nb$_2$O$_9$ (x=1) could serve as a potential material candidate\nfor applications in future logic spintronics and logic devices.",
        "positive": "Voltage induced control and magnetoresistance of noncollinear frustrated\n  magnets: Noncollinear frustrated magnets are proposed as a new class of spintronic\nmaterials with high magnetoresistance which can be controlled with relatively\nsmall applied voltages. It is demonstrated that their magnetic configuration\nstrongly depends on position of the Fermi energy and applied voltage. The\nvoltage induced control of noncollinear frustrated materials (VCFM) can be seen\nas a way to intrinsic control of colossal magnetoresistance (CMR) and is the\nbulk material counterpart of spin transfer torque concept used to control giant\nmagnetoresistance in layered spin-valve structures."
    },
    {
        "anchor": "Interplay between ferroic orders at the FeRh/BaTiO$_3$ interfaces: It has been recently demonstrated that the magnetic state of FeRh can be\ncontrolled by electric fields in FeRh/BaTiO$_{\\text{3}}$ heterostructures [R.O.\nCherifi et al. Nature Mater. 13, 345 (2014)]. Voltage-controlled changes in the\nferroelastic domain structure of BaTiO$_3$ appeared to drive this effect, with\ncharge accumulation and depletion due to ferroelectricity playing a more\nelusive role. To make this electric-field control of magnetic order\nnon-volatile, the contribution of ferroelectric field-effect must be further\nenhanced, which requires understanding the details of the interface between\nFeRh and BaTiO$_3$. Here we report on the atomic structure and electron\nscreening at this interface through density functional theory simulations. We\nrelate different screening capabilities for the antiferromagnetic and\nferromagnetic states of FeRh to different density of states at the Fermi level\nof corresponding bulk structures. We predict that the stability of the\nferroelectric state in adjacent very thin BaTiO$_3$ films will be affected by\nmagnetic order in FeRh. This control of ferroelectricity by magnetism can be\nviewed as the reciprocal effect of the voltage-controlled magnetic order\npreviously found for this system.",
        "positive": "Stabilization of the oxygen concentration in\n  La$_{0.3}$Sr$_{0.7}$CoO$_{3-\u03b4}$ thin films by LaAlO$_3$ capping layer: We have grown La$_{0.3}$Sr$_{0.7}$CoO$_{3-{\\delta}}$ thin films by pulsed\nlaser deposition on (LaAlO$_3$)$_{0.3}$(Sr$_2$TaAlO$_3$)$_{0.7}$ substrates\nwith and without a protective LaAlO$_3$ capping layer and investigated their\nstructural and magnetic properties. We have observed that, in the uncapped\nfilms, the Curie temperature strongly decreased after annealing in helium\natmosphere, and it significantly decreased even in samples stored for several\nweeks at room temperature. The decrease of the Currie temperature is caused by\nan increase of the concentration of oxygen vacancies, {\\delta}. However, we\nshow that already a 3 nm thin LaAlO$_3$ capping layer can essentially conserve\n{\\delta} at room temperature, and it considerably slows down the formation of\noxygen vacancies at elevated temperatures."
    },
    {
        "anchor": "Model for the on-site matrix elements of the tight-binding hamiltonian\n  of a strained crystal: Application to silicon, germanium and their alloys: We discuss a model for the on-site matrix elements of the sp3d5s*\ntight-binding hamiltonian of a strained diamond or zinc-blende crystal or\nnanostructure. This model features on-site, off-diagonal couplings between the\ns, p and d orbitals, and is able to reproduce the effects of arbitrary strains\non the band energies and effective masses in the full Brillouin zone. It\nintroduces only a few additional parameters and is free from any ambiguities\nthat might arise from the definition of the macroscopic strains as a function\nof the atomic positions. We apply this model to silicon, germanium and their\nalloys as an illustration. In particular, we make a detailed comparison of\ntight-binding and ab initio data on strained Si, Ge and SiGe.",
        "positive": "An effective spin model on the honeycomb lattice for the description of\n  magnetic properties in two-dimensional Fe$_3$GeTe$_2$: Fe$_3$GeTe$_2$ attracts significant attention due to technological\nperspectives of realizing room temperature ferromagnetism in two-dimensional\nmaterials. Here we show that due to structural peculiarities of the\nFe$_3$GeTe$_2$ monolayer, short distance between the neighboring iron atoms\ninduces a strong exchange coupling. This strong coupling allows us to consider\nthem as an effective cluster with a magnetic moment $\\sim$5 $\\mu_B$, giving\nrise to a simplified spin model on a bipartite honeycomb lattice with the\nreduced number of long-range interactions. The simplified model perfectly\nreproduces the results of the conventional spin model, but allows for a more\ntractable description of the magnetic properties of Fe$_3$GeTe$_2$, which is\nimportant, e.g., for large-scale simulations. Also, we discuss the role of\nbiaxial strain in the stabilization of ferromagnetic ordering in\nFe$_3$GeTe$_2$."
    },
    {
        "anchor": "Unpinning the skyrmion lattice in MnSi:Effect of substitutional disorder: By employing magnetization and small angle neutron scattering (SANS)\nmeasurements, we have investigated the behavior of the skyrmion lattice (SKL)\nand the helical order in MnSi0.992Ga0.008. Our results indicate that the order\nof the SKL is sensitive to the orientation of an applied magnetic field with\nrespect to the crystal lattice and small variations in the sequence of\ntemperature and applied magnetic field changes. The disorder caused by the\nsubstitution of the heavier element Ga for Si is sufficient to reduce the\npinning of the SKL to the underlying crystalline lattice. This reduces the\npropensity for the SKL to be aligned with the crystal lattice. This tendency is\nmost evident when the applied field is not well oriented with respect to the\nhigh symmetry axes of the crystal resulting in disorder in the long range SKL\nwhile maintaining sharp radial order. We have also investigated the effect of\nsubstituting heavier elements into MnSi on the reorientation process of the\nhelical domains with field cycling in MnSi0.992Ga0.008 and Mn0.985Ir0.015Si. A\ncomparison of the reorientation process in these materials with field reduction\nindicates that the substitution of heavier elements on either Mn or Si sites\ncreates a higher energy barrier for the reorientation of the helical order and\nfor the formation of domains.",
        "positive": "Effects of normal and oblique incidence on zero-n gap in periodic lossy\n  multilayer containing double-negative materials: In this paper the transmission of electromagnetic waves through a\none-dimensional lossy photonic crystal consisting of layers with negative and\npositive refractive indices is investigated. The behavior and characteristics\nof the bandwidth, the depth and the central frequency of the zero-n gap for\ndifferent incidence angles, polarization, loss factor and ratios of thickness\nof the layers are studied. The results show that the gap is very sensitive to\nthe incidence angle, polarization and the thickness ratio, but it is nearly\ninsensitive to small loss factor. Such properties are quite useful in designing\nnew types of edge filters and other optical devices in microwave engineering."
    },
    {
        "anchor": "Vortex core dynamics induced by hole defects in antiferromagnetic\n  nanodisks: Direct observation of vortex states in an antiferromagnetic layer have been\nrecently reported [Wu, et al, Nature Phys. 7, 303 (2011)]. In contrast to their\nanalogues in ferromagnetic systems, namely in nanomagnets, the vortex core of\nantiferromagnets are not expected (and have not been observed) to present\ngyrotropic or any other remarkable dynamics, even when external fields are\napplied. Using simulated annealing and spin dynamics techniques we have been\nable to describe a number of properties of such a vortex state. Besides of\nbeing in agreement with reported results, our results also indicate, whenever\napplied to antiferromagnetic nanodisks, that the presence of holes in the\nsample may induce two types of motions for this vortex. Its dynamics depends\nupon the relative separation between its core and the hole: when they are very\napart the vortex core oscillates near the nanodisk center (its equilibrium\nposition); while, if they are sufficiently close, the core moves towards the\nhole where it is captured and remains static.",
        "positive": "Direct Measurement of Room Temperature Non-diffusive Thermal Transport\n  Over Micron Distances in a Silicon Membrane: The \"textbook\" phonon mean free path (MFP) of heat carrying phonons in\nsilicon at room temperature is ~40 nm. However, a large contribution to the\nthermal conductivity comes from low-frequency phonons with much longer MFPs. We\npresent a simple experiment demonstrating that room temperature thermal\ntransport in Si significantly deviates from the diffusion model already at\nmicron distances. Absorption of crossed laser pulses in a freestanding silicon\nmembrane sets up a sinusoidal temperature profile that is monitored via\ndiffraction of a probe laser beam. By changing the period of the thermal\ngrating we vary the heat transport distance within the range ~1-10 {\\mu}m. At\nsmall distances, we observe a reduction in the effective thermal conductivity\nindicating a transition from the diffusive to the ballistic transport regime\nfor the low-frequency part of the phonon spectrum."
    },
    {
        "anchor": "In situ AC-hysteresis measurements of SPD-processed Cu20(Fe15Co85)80: The changes of magnetic properties upon heat treatment of a metastable\nsupersaturated solid solution processed by severe plastic deformation are\ninvestigated by in-situ AC-hysteresis measurements. Data are analyzed in the\nframework of dynamic loss theory, with correlative investigations of the\nmicrostructural properties. The evolution of hysteresis upon annealing points\nout that the single-phase supersaturated solid solution remains stable up to\n400{\\deg}C, then hindering of domain wall motion sets in at this temperature.\nAt 600{\\deg}C, a multi phase microstructure is present, causing a significant\nincrease in coercivity.",
        "positive": "CDPM2: A damage-plasticity approach to modelling the failure of concrete: A constitutive model based on the combination of damage mechanics and\nplasticity is developed to analyse the failure of concrete structures. The aim\nis to obtain a model, which describes the important characteristics of the\nfailure process of concrete subjected to multiaxial loading. This is achieved\nby combining an effective stress based plasticity model with a damage model\nbased on plastic and elastic strain measures. The model response in tension,\nuni-, bi- and triaxial compression is compared to experimental results. The\nmodel describes well the increase in strength and displacement capacity for\nincreasing confinement levels. Furthermore, the model is applied to the\nstructural analyses of tensile and compressive failure."
    },
    {
        "anchor": "Quantitative understanding of negative thermal expansion in scandium\n  trifluoride from neutron total scattering measurements: Negative thermal expansion (NTE) - the phenomenon where some materials shrink\nrather than expand when heated - is both intriguing and useful, but remains\npoorly understood. Current understanding hinges on the role of specific\nvibrational modes, but in fact thermal expansion is a weighted sum of\ncontributions from every possible mode. Here we overcome this difficulty by\nderiving a real-space model of atomic motion in the prototypical NTE material\nscandium trifluoride, ScF3, from total neutron scattering data. We show that\nNTE in this material depends not only on rigid unit modes - the vibrations in\nwhich the scandium coordination octahedra remain undistorted - but also on\nmodes that distort these octahedra. Furthermore, in contrast with previous\npredictions, we show that the quasiharmonic approximation coupled with\nrenormalisation through anharmonic interactions describes this behaviour well.\nOur results point the way towards a new understanding of how NTE is manifested\nin real materials.",
        "positive": "Ab Initio Models of Dislocations: This chapter reviews the different methodological aspects of the ab ini-tio\nmodeling of dislocations. Such simulations are now frequently used to study the\ndislocation core, i.e. the region in the immediate vicinity of the line defect\nwhere the crystal is so strongly distorted that an atomic description is\nneeded. This core region controls some dislocation fundamental properties, like\ntheir ability to glide in different crystallographic planes. Ab initio\ncalculations based on the density functional theory offer a predictive way to\nmodel this core region. Because dislocations break the periodicity of the\ncrystal and induce long range elastic fields, several specific approaches\nrelying on different boundary conditions have been developed to allow for the\natomistic modeling of these defects in simulation cells having a size\ncompatible with ab initio calculations. We describe these different approaches\nwhich can be used to study dislocations with ab initio calculations and\nintroduce the different analyses which are currently performed to characterize\nthe core structure, before discussing how meaningful energy properties can be\nextracted from such simulations."
    },
    {
        "anchor": "A Symmetry-orientated Divide-and-Conquer Method for Crystal Structure\n  Prediction: Crystal structure prediction has been a subject of topical interest, but\nremains a substantial challenge, especially for complex structures as it deals\nwith the global minimization of the extremely rugged high-dimensional potential\nenergy surface. In this manuscript, a symmetry-orientated divide-and-conquer\nscheme was proposed to construct a symmetry tree graph, where the entire search\nspace is decomposed into a finite number of symmetry-dependent subspaces. An\nartificial intelligence-based symmetry selection strategy was subsequently\ndevised to select the low-lying subspaces with high symmetries for global\nexploration and in-depth exploitation. Our approach can significantly simplify\nthe problem of crystal structure prediction by avoiding exploration of the most\ncomplex P1 subspace on the entire search space and have the advantage of\npreserving the crystal symmetry during structure evolution, making it well\nsuitable for predicting the complex crystal structures. The effectiveness of\nthe method has been validated by successful prediction of the candidate\nstructures of binary Lennard-Jones mixtures and high-pressure phase of ice,\ncontaining more than one hundred atoms in the simulation cell. The work,\ntherefore, opens up an opportunity towards achieving the long-sought goal for\ncrystal structure prediction of complex systems.",
        "positive": "Highly Tunable Band Inversion in AB2X4 (A=Ge, Sn, Pb; B=As, Sb, Bi;\n  X=Se, Te) Compounds: Topological materials have been discovered so far largely by searching for\nexisting compounds in crystallographic databases, but there are potentially new\ntopological materials with desirable features that have not been synthesized.\nOne of the desirable features is high tunability resulted from the band\ninversion with a very small direct band gap, which can be tuned by changes in\npressure or strain to induce a topological phase transition. Using density\nfunctional theory (DFT) calculations, we have studied the septuple layered\nAB2X4 series compounds, where A=(Ge, Sn and Pb), B=(As, Sb and Bi) and X=(Se\nand Te). With the DFT thermodynamic stability validated by the already reported\ncompounds in these series, we predict new stable Se compounds, which are not\nfound in crystallographic database. Among them, we find that GeBi2Se4 and\nGeSb2Se4 having a small direct band gap at the Z point are very close to a\nstrong topological insulator, which can be tuned by a moderate pressure to\ninduce the band inversion. Importantly, the topological features with the small\ndirect band gap are well isolated in both momentum and energy windows, which\noffers high tunability for studying the topological phase transition."
    },
    {
        "anchor": "Effects of annealing time on structural and magnetic properties of\n  L10-FePt nanoparticles synthesized by the SiO2-nanoreactor method: We investigated effects of annealing time on structural and magnetic\nproperties of the L10-FePt nanoparticles synthesized by the SiO2-nanoreacter\nmethod. The magnetization and powder X-ray diffraction studies revealed that\nthe annealing at 900 oC for 9 hr could convert all of the fcc-nanoparticles to\nthe well-crystallized L10 structure with a large coercivity while keeping their\nparticle size. Such monodisperse and highly crystalline L10-FePt nanoparticles\nare a promising material for the realization of ultra-high density recording.",
        "positive": "Origin of ferromagnetism in Cs$_2$AgF$_4$: importance of Ag - F\n  covalency: The magnetic nature of Cs$_{2}$AgF$_{4}$, an isoelectronic and isostructural\nanalogue of La$_2$CuO$_4$, is analyzed using density functional calculations.\nThe ground state is found to be ferromagnetic and nearly half metallic. We find\nstrong hybridization of Ag-$d$ and F-$p$ states. Substantial moments reside on\nthe F atoms, which is unusual for the halides and reflects the chemistry of the\nAg(II) ions in this compound. This provides the mechanism for ferromagnetism,\nwhich we find to be itinerant in character, a result of a Stoner instability\nenhanced by Hund's coupling on the F."
    },
    {
        "anchor": "Comments on \"Band gap and band parameters of InN and GaN from\n  quasiparticle energy calculations based on exact-exchange density-functional\n  theory\" [Appl. Phys. Lett. 89, 161919 (2006)]: An oversight of some previous density functional calculations of the band\ngaps of wurtzite and cubic InN and of wurtzite GaN by Rinke et al. [Appl. Phys.\nLett. 89,161919, 2006] led to an inaccurate and misleading statement relative\nto limitations of density functional theory (DFT) for the description of\nelectronic properties of these materials. These comments address this\nstatement. In particular, they show that some local density approximation (LDA)\ncalculations have correctly described or predicted electronic and related\nproperties of these systems [Phys. Rev. B 60, 1563, 1999; J. Appl. Phys. 96,\n4297, 2004, and 97, 123708, 2005]. These successful calculations solved\nself-consistently the system of equations defining LDA, i.e., the Kohn-Sham\nequation and the equation giving the ground state charge density in terms of\nthe wave functions of the occupied states.",
        "positive": "Calculation of the work function with a local basis set: Electronic structure codes usually allow to calculate the work function as a\npart of the theoretical description of surfaces and processes such as\nadsorption thereon. This requires a proper calculation of the electrostatic\npotential in all regions of space, which is apparently straightforward to\nachieve with plane wave basis sets, but more difficult with local basis sets.\nTo overcome this, a relatively simple scheme is proposed to accurately compute\nthe work function when a local basis set is used, by having some additional\nbasis functions in the vacuum. Tests on various surfaces demonstrate that a\nvery good agreement with experimental and other theoretical data can be\nachieved."
    },
    {
        "anchor": "Nonlinear dynamic susceptibilities of interacting and noninteracting\n  nanoparticle systems: The linear and cubic dynamic susceptibilities of solid dispersions of\nnano-sized maghemite particles have been measured for three samples with a\nvolume concentration of magnetic particles ranging from 0.3 % to 17 %, in order\nto study the effect of dipole-dipole interactions. Significant differences\nbetween the dynamic response of the three samples are observed. The dynamic\nsusceptibilities of the most dilute sample compare reasonably well with an\nexisting theory for the linear and cubic dynamic susceptibilities of an\nassembly of noninteracting, uniaxial magnetic particles. The nonlinear dynamic\nresponse of the most concentrated sample exhibits at low temperatures some of\nthe features observed in a Ag(11 at.% Mn) spin glass.",
        "positive": "The delayed fracture test for viscoelastic elastomers: In a recent contribution, Shrimali and Lopez-Pamies (2023) have shown that\nthe Griffith criticality condition that governs crack growth in viscoelastic\nelastomers can be reduced -- from its ordinary form involving a historically\nelusive loading-history-dependent critical tearing energy $T_c$ -- to a\nfundamental form that involves exclusively the intrinsic fracture energy $G_c$\nof the elastomer. The purpose of this paper is to make use of this fundamental\nform to explain one of the most distinctive fracture tests for viscoelastic\nelastomers, the so-called delayed fracture test."
    },
    {
        "anchor": "Ab initio study of the interface properties of Fe/GaAs(110): We have investigated the initial growth of Fe on GaAs(110) by means of\ndensity functional theory. In contrast to the conventionally used (001)-surface\nthe (110)-surface does not reconstruct. Therefore, a flat interface and small\ndiffusion can be expected, which makes Fe/GaAs(110) a possible candidate for\nspintronic applications. Since experimentally, the actual quality of the\ninterface seems to depend on the growth conditions, e.g., on the flux rate, we\nsimulate the effect of different flux rates by different Fe coverages of the\nsemiconductor surface. Systems with low coverages are highly diffusive. With\nincreasing amount of Fe, i.e., higher flux rates, a flat interface becomes more\nstable. The magnetic structure strongly depends on the Fe coverage but no\nquenching of the magnetic moments is observed in our calculations.",
        "positive": "Strong diamagnetic response of metamaterials: We demonstrate that there is a strong diamagnetic response of metamaterials,\nconsisting of open or closed split ring resonators (SRRs). Detailed numerical\nwork shows that for densely packed SRRs the magnetic permeability,\n$\\mu(\\omega)$, does not approach unity, as expected for frequencies lower and\nhigher than the resonance frequency, $\\omega_0$. Below $\\omega_0$,\n$\\mu(\\omega)$ gives values ranging from 0.9 to 0.6 depending of the width of\nthe metallic ring, while above $\\omega_0$, $\\mu(\\omega)$ is close to 0.5.\nClosed rings have $\\mu\\approx 0.5$ over a wide frequency range independently of\nthe width of the ring. A simple model that uses the inner and outer current\nloop of the SRRs can easily explain theoretically this strong diamagnetic\nresponse, which can be used in magnetic levitation."
    },
    {
        "anchor": "Inverse simulated annealing for the determination of amorphous\n  structures: We present a new and efficient optimization method to determine the structure\nof disordered systems in agreement with available experimental data. Our\napproach permits the application of accurate electronic structure calculations\nwithin the structure optimization. The new technique is demonstrated within\ndensity functional theory by the calculation of a model of amorphous carbon.",
        "positive": "Spin pumping and inverse spin Hall effect in iridium oxide: Large charge-to-spin conversion (spin Hall angle) and spin Hall conductivity\nare prerequisites for development of next generation power efficient spintronic\ndevices. In this context, heavy metals (e.g. Pt, W etc.), topological\ninsulators, antiferromagnets are usually considered because they exhibit high\nspin-orbit coupling (SOC). In addition to the above materials, 5d transition\nmetal oxide e.g. Iridium Oxide (IrO 2 ) is a potential candidate which exhibits\nhigh SOC strength. Here we report a study of spin pumping and inverse spin Hall\neffect (ISHE), via ferromagnetic resonance (FMR), in IrO 2 /CoFeB system. We\nidentify the individual contribution of spin pumping and other spin\nrectification effects in the magnetic layer, by investigating the in-plane\nangular dependence of ISHE signal. Our analysis shows significant contribution\nof spin pumping effect to the ISHE signal. We show that polycrystalline IrO 2\nthin film exhibits high spin Hall conductivity and spin Hall angle which are\ncomparable to the values of Pt."
    },
    {
        "anchor": "Surface-oxygen-passivation driven large anomalous Hall conductivity\n  (AHC) in nitride MXenes: Can AHC be a tool to determine functional groups in\n  2D ferro(i)magnets?: Identifying the existence of specific functional groups in MXenes is a\ndifficult topic that has perplexed researchers for a long time. We show in this\npaper that in the case of magnetic MXenes, the magneto-transport properties of\nthe material provide an easy solution. One of the fascinating properties that\nMXenes offer is the realization of intrinsic ferromagnetism which is important\nfor two-dimensional (2D) materials family. The previous reports have only made\na few statements on some MXenes citing its usefulness for spintronics related\napplications. Here, using first-principle calculations we have examined the\nactual magneto-transport phenomena in MXenes family. We have considered all\npossible combinations of 3\\textit{d} transition metals ($Ti, V, Cr$ and $Mn$)\nand nitride based functionalized $(O_2, F_2$ and $(OH)_2$) MXenes, $M_2NT_2$.\nThe intrinsic anomalous Hall effect is investigated in $Cr$ and $Mn$ based\nMXenes as the compounds possess ground state stable ferromagnetic solutions. We\ndemonstrate that intrinsic Anomalous Hall conductivity (AHC) can be used to\nidentify the functional groups in MXenes.\n  Additionally, half-metallic features of these ferromagnetic MXenes make them\npotential candidates for varieties of applications such as in logic and memory\ndevices, quantum computations, spintronics etc. The maximum anomalous Hall\nconductivity (AHC) at Fermi energy, $E_F$, is found in case of $Mn_2NO_2$ (470\n$S/cm$) which is attributed to the presence of avoided band crossing and larger\ndensity of states. Together, when considered all the studied systems, the AHC\ncan be above 2500 $S/cm$ within $E_F \\pm $ 0.25 $eV$. Our findings could be\nuseful not only in guiding the experimentalists by considering AHC as a simple\ntool in determining the functional groups in 2D ferro(i)magnets, also, it could\nbe useful in designing memory device with negligible stray fields.",
        "positive": "Low compressible BP$_3$N$_6$: Using first principles calculation, the structural and mechanical properties\nof BP$_3$N$_6$ which adopts an orthorhombic structure with space group Pna2$_1$\n(no. 33), were determined at three different pressure values (0, 20 and\n42.4~GPa). The nine independent elastic constants meet all necessary and\nsufficient conditions for mechanical stability criteria for an orthorhombic\ncrystal. BP$_3$N$_6$ show strong resistance to volume change hence a potential\nlow compressible material. The Vicker's hardness of BP$_3$N$_6$ was found to\nrange between 49-51~GPa for different external pressures imposed on the\ncrystal. These high values of Vicker's hardness implies that BP$_3$N$_6$ is a\npotential superhard material."
    },
    {
        "anchor": "Role of the spin-orbit splitting and the dynamical fluctuations in the\n  Si(557)-Au surface: Our it ab initio calculations show that spin-orbit coupling is crucial to\nunderstand the electronic structure of the Si(557)-Au surface. The spin-orbit\nsplitting produces the two one-dimensional bands observed in photoemission,\nwhich were previously attributed to spin-charge separation in a Luttinger\nliquid. This spin splitting might have relevance for future device\napplications. We also show that the apparent Peierls-like transition observed\nin this surface by scanning tunneling microscopy is a result of the dynamical\nfluctuations of the step-edge structure, which are quenched as the temperature\nis decreased.",
        "positive": "AFLOW-ML: A RESTful API for machine-learning predictions of materials\n  properties: Machine learning approaches, enabled by the emergence of comprehensive\ndatabases of materials properties, are becoming a fruitful direction for\nmaterials analysis. As a result, a plethora of models have been constructed and\ntrained on existing data to predict properties of new systems. These powerful\nmethods allow researchers to target studies only at interesting materials\n$\\unicode{x2014}$ neglecting the non-synthesizable systems and those without\nthe desired properties $\\unicode{x2014}$ thus reducing the amount of resources\nspent on expensive computations and/or time-consuming experimental synthesis.\nHowever, using these predictive models is not always straightforward. Often,\nthey require a panoply of technical expertise, creating barriers for general\nusers. AFLOW-ML (AFLOW $\\underline{\\mathrm{M}}$achine\n$\\underline{\\mathrm{L}}$earning) overcomes the problem by streamlining the use\nof the machine learning methods developed within the AFLOW consortium. The\nframework provides an open RESTful API to directly access the continuously\nupdated algorithms, which can be transparently integrated into any workflow to\nretrieve predictions of electronic, thermal and mechanical properties. These\ntypes of interconnected cloud-based applications are envisioned to be capable\nof further accelerating the adoption of machine learning methods into materials\ndevelopment."
    },
    {
        "anchor": "On the link between Octahedral Rotations and Conductivity in the Domain\n  Walls of BiFeO3: We analyze the hypothetical link between octahedral straightening and\nincreased conductivity inside the domain walls of BiFeO3. Our calculations for\n109 degree walls predict a lattice parameter expansion of c.a. 1 percent in the\ndirection perpendicular to the wall, and an associated straightening of the\noctahedral rotation angle of 4 degrees, which is comparable to that observed in\nthe high temperature metallic phase of BiFeO3. On the other hand, in the\nclosely related family of rare-earth orthoferrites, straighter octahedra do not\ncorrelate with increased bandgap, which suggests that the correlation between\noctahedral straightening and bandgap reduction in BiFeO3 is perhaps fortuitous\nand not necessarily the cause of increased conductivity at the walls.",
        "positive": "Learning Properties of Ordered and Disordered Materials from\n  Multi-fidelity Data: Predicting the properties of a material from the arrangement of its atoms is\na fundamental goal in materials science. While machine learning has emerged in\nrecent years as a new paradigm to provide rapid predictions of materials\nproperties, their practical utility is limited by the scarcity of high-fidelity\ndata. Here, we develop multi-fidelity graph networks as a universal approach to\nachieve accurate predictions of materials properties with small data sizes. As\na proof of concept, we show that the inclusion of low-fidelity\nPerdew-Burke-Ernzerhof band gaps greatly enhances the resolution of latent\nstructural features in materials graphs, leading to a 22-45\\% decrease in the\nmean absolute errors of experimental band gap predictions. We further\ndemonstrate that learned elemental embeddings in materials graph networks\nprovide a natural approach to model disorder in materials, addressing a\nfundamental gap in the computational prediction of materials properties."
    },
    {
        "anchor": "Enhanced thermally-activated skyrmion diffusion with tunable effective\n  gyrotropic force: Magnetic skyrmions, topologically-stabilized spin textures that emerge in\nmagnetic systems, have garnered considerable interest due to a variety of\nelectromagnetic responses that are governed by the topology. The topology that\ncreates a microscopic gyrotropic force also causes detrimental effects, such as\nthe skyrmion Hall effect, which is a well-studied phenomenon highlighting the\ninfluence of topology on the deterministic dynamics and drift motion.\nFurthermore, the gyrotropic force is anticipated to have a substantial impact\non stochastic diffusive motion; however, the predicted repercussions have yet\nto be demonstrated, even qualitatively. Here we demonstrate enhanced\nthermally-activated diffusive motion of skyrmions in a specifically designed\nsynthetic antiferromagnet. Suppressing the effective gyrotropic force by tuning\nthe angular momentum compensation leads to a more than 10 times enhanced\ndiffusion coefficient compared to that of ferromagnetic skyrmions.\nConsequently, our findings not only demonstrate the gyro-force dependence of\nthe diffusion coefficient but also enable ultimately energy-efficient\nunconventional stochastic computing.",
        "positive": "Structure and elastic properties of Mg(OH)$_2$ from density functional\n  theory: The structure, lattice dynamics and mechanical properties of the magnesium\nhydroxide have been investigated with static density functional theory\ncalculations as well as \\it {ab initio} molecular dynamics. The hypothesis of a\nsuperstructure existing in the lattice formed by the hydrogen atoms has been\ntested. The elastic constants of the material have been calculated with static\ndeformations approach and are in fair agreement with the experimental data. The\nhydrogen subsystem structure exhibits signs of disordered behaviour while\nmaintaining correlations between angular positions of neighbouring atoms. We\nestablish that the essential angular correlations between hydrogen positions\nare maintained to the temperature of at least 150 K and show that they are well\ndescribed by a physically motivated probabilistic model. The rotational degree\nof freedom appears to be decoupled from the lattice directions above 30K."
    },
    {
        "anchor": "Crossed ratchet effects for magnetic domain wall motion: We study both experimentally and theoretically the driven motion of domain\nwalls in extended amorphous magnetic films patterned with a periodic array of\nasymmetric holes. We find two crossed ratchet effects of opposite sign that\nchange the preferred sense for domain wall propagation, depending on whether a\nflat or a kinked wall is moving. By solving numerically a simple $\\phi^4$-model\nwe show that the essential physical ingredients for this effect are quite\ngeneric and could be realized in other experimental systems involving elastic\ninterfaces moving in multidimensional ratchet potentials.",
        "positive": "Domain wall motion of magnetic nanowires under a static field: The propagation of a head-to-head magnetic domain-wall (DW) or a tail-to-tail\nDW in a magnetic nanowire under a static field along the wire axis is studied.\nRelationship between the DW velocity and DW structure is obtained from the\nenergy consideration. The role of the energy dissipation in the field-driven DW\nmotion is clarified. Namely, a field can only drive a domain-wall propagating\nalong the field direction through the mediation of a damping. Without the\ndamping, DW cannot propagate along the wire. Contrary to the common wisdom, DW\nvelocity is, in general, proportional to the energy dissipation rate, and one\nneeds to find a way to enhance the energy dissipation in order to increase the\npropagation speed. The theory provides also a nature explanation of the\nwire-width dependence of the DW velocity and velocity oscillation beyond Walker\nbreakdown field."
    },
    {
        "anchor": "Amorphous interface layer in thin graphite films grown on the carbon\n  face of SiC: Cross-sectional transmission electron microscopy (TEM) is used to\ncharacterize an amorphous layer observed at the interface in graphite and\ngraphene films grown via thermal decomposition of C-face 4H-SiC. The amorphous\nlayer does not to cover the entire interface, but uniform contiguous regions\nspan microns of cross-sectional interface. Annular dark field scanning\ntransmission electron microscopy (ADF-STEM) images and electron energy loss\nspectroscopy (EELS) demonstrate that the amorphous layer is a carbon-rich\ncomposition of Si/C. The amorphous layer is clearly observed in samples grown\nat 1600{\\deg}C for a range of growth pressures in argon, but not at\n1500{\\deg}C, suggesting a temperature-dependent formation mechanism.",
        "positive": "Transition metal impurity effect on charge and spin density in iron: Ab\n  initio calculations and comparison with M\u00f6ssbauer data: Density functional theory was applied to study influence of the isolated\nimpurity located on the regular site of the alpha-Fe crystal on the charge and\nspin density (hyperfine interactions) on the iron nucleus. Calculations were\nperformed by using both pseudopotential and the full potential methods. The\nscalar relativistic approximation was applied. Perturbations of the charge and\nspin density on iron were calculated for all d impurities soluble in iron and\nadditionally for Ga impurity. It was found that impurities have measurable\neffect on the iron charge and spin density up to the second or third\ncoordination shell depending on the impurity. Hyperfine parameters of iron\nadjacent to the impurity are affected by two intermixed physical mechanisms,\ni.e., the volume mismatch due to the impurity and electron band mixing caused\nby the electronic configuration of the impurity outer shells. Some correlations\nbetween ab initio calculations and Moessbauer experimental results are\ndiscussed. A table is provided with the parameters allowing calculate\nMoessbauer spectrum of the binary iron alloy with d impurity or Ga. On the\nother hand, provided parameters allow extraction from the Moessbauer data\ninformation about impurity concentration and eventual order."
    },
    {
        "anchor": "Wafer-scale epitaxial growth of the thickness-controllable van der Waals\n  ferromagnet CrTe2 for reliable magnetic memory applications: To harness the intriguing properties of two-dimensional van der Waals (vdW)\nferromagnets (FMs) for versatile applications, the key challenge lies in the\nreliable material synthesis for scalable device production. Here, we\ndemonstrate the epitaxial growth of single-crystalline 1T-CrTe2 thin films on\n2-inch sapphire substrates. Benefiting from the uniform surface energy of the\ndangling bond-free Al2O3(0001) surface, the layer-by-layer vdW growth mode is\nobserved right from the initial growth stage, which warrants precise control of\nthe sample thickness and atomically smooth surface morphology across the entire\nwafer. Moreover, the presence of the Coulomb interaction at the CrTe2/Al2O3\ninterface serves as an effective tuning parameter to tailor the anomalous Hall\nresponse, and the structural optimization of the CrTe2-based spin-orbit torque\ndevice leads to a substantial switching power reduction by 54%. Our results may\nlay out a general framework for the design of energy-efficient spintronics\nbased on configurable vdW FMs.",
        "positive": "Anharmonic free energies and phonon dispersions from the stochastic\n  self-consistent harmonic approximation: application to platinum and palladium\n  hydrides: Harmonic calculations based on density-functional theory are generally the\nmethod of choice for the description of phonon spectra of metals and\ninsulators. The inclusion of anharmonic effects is, however, delicate as it\nrelies on perturbation theory requiring a considerable amount of computer time,\nfast increasing with the cell size. Furthermore, perturbation theory breaks\ndown when the harmonic solution is dynamically unstable or the anharmonic\ncorrection of the phonon energies is larger than the harmonic frequencies\nthemselves.We present a stochastic implementation of the self-consistent\nharmonic approximation valid to treat anharmonicity at any temperature in the\nnon-perturbative regime. The method is based on the minimization of the free\nenergy with respect to a trial density matrix described by an arbitrary\nharmonic Hamiltonian. The minimization is performed with respect to all the\nfree parameters in the trial harmonic Hamiltonian, namely, equilibrium\npositions, phonon frequencies and polarization vectors. The gradient of the\nfree energy is calculated following a stochastic procedure. The method can be\nused to calculate thermodynamic properties, dynamical properties and anharmonic\ncorrections to the Eliashberg function of the electron-phonon coupling. The\nscaling with the system size is greatly improved with respect to perturbation\ntheory. The validity of the method is demonstrated in the strongly anharmonic\npalladium and platinum hydrides. In both cases we predict a strong anharmonic\ncorrection to the harmonic phonon spectra, far beyond the perturbative limit.\nIn palladium hydrides we calculate thermodynamic properties beyond the\nquasiharmonic approximation, while in PtH we demonstrate that the high\nsuperconducting critical temperatures at 100 GPa predicted in previous\ncalculations based on the harmonic approximation are strongly suppressed when\nanharmonic effects are included."
    },
    {
        "anchor": "Optimal control of vortex core polarity by resonant microwave pulses: In a vortex-state magnetic nano-disk, the static magnetization is curling in\nthe plane, except in the core region where it is pointing out-of-plane, either\nup or down leading to two possible stable states of opposite core polarity p.\nDynamical reversal of p by large amplitude motion of the vortex core has\nrecently been demonstrated experimentally,raising fundamental interest for\npotential application in magnetic storage devices. Here we demonstrate coherent\ncontrol of p by single and double microwave pulse sequences, taking advantage\nof the resonant vortex dynamics in a perpendicular bias magnetic field.\nOptimization of the microwave pulse duration required to switch p allows to\nexperimentally infer the characteristic decay time of the vortex core in the\nlarge oscillation regime. It is found to be more than twice shorter than in the\nsmall oscillation regime, raising the fundamental question of the non-linear\nbehaviour of magnetic dissipation.",
        "positive": "A novel two-mechanism full battery model for solid state Li-ion\n  batteries: review and comparisons: In recent years there has been a major interest in developing all solid state\nbatteries, for the sake of safety (issues due to toxic and flammable organic\nliquid electrolytes are well known) as well as of high energy density\n\\cite{SCHNELL2018160,Zheng2018}. Side by side to experimental investigations,\ncomputational simulations \\cite{GrazioliEtAlCM2016} unveil the several physics\nthat interconnect at different scales \\cite{LiMonroeARCBM2020} during battery\noperations. %Several advanced mathematical models have therefore been published\n\\cite{bistriM2020}. We propose herein a new advanced model, which is multiscale\ncompatible and fully three dimensional in nature. Furthermore, we review some\nclassical or inspiring models, highlighting the conceptual evolutions that are\nultimately collected in our work. The model is validated against experimental\nevidences of a Li/LiPON/LiCoO$_2$ thin film battery published in\n\\cite{Danilovetal2011}."
    },
    {
        "anchor": "Local structural distortion induced by antiferromagnetic ordering in\n  Bi$_2$Fe$_4$O$_9$ studied using neutron total scattering analysis: To unravel the origin of the dielectric anomaly at the antiferromagnetic\nordering of magnetoelectric Bi$_2$Fe$_4$O$_9$ we performed neutron powder\ndiffraction measurements across the N$\\acute{\\rm e}$el temperature, $T_{\\rm\nN}$. Both local structures and long-range symmetry are studied using the\ncomplementary analyses of atomic pair distribution function (PDF) and Rietveld\nmethods at temperatures 300~K, 250~K, and 200~K. We present that PDF peaks\nwhich reflect local atomic arrangements exhibit a noticeable variation below\n$T_{\\rm N}$ without long-range symmetry change. The implication of the PDF\nevolution is discussed in view of a local structural distortion at the onset of\nthe antiferromagnetic ordering.",
        "positive": "Reentrant cluster glass behavior in La2CoMnO6 nanoparticles: Magnetic study on La2CoMnO6 nanoparticles revealed multiple magnetic\ntransitions at 218 K, 135 K and below 38 K and the nature of the low\ntemperature transition was unclear [J Appl Phys 111, 024102 2012]. Presence of\nmixed valance states of Co and Mn has been confirmed from the XPS measurement\nand its presence along with antisite disorder affects in reducing the\nsaturation magnetization of the nanoparticles. The zero field cooled and field\ncooled bifurcation in dc magnetization, relaxation in zero field cooled\nmagnetization and large enhancement in coercive field below the glassy\ntemperature has been discussed. Frequency dependence of ac susceptibility using\npower law has revealed cluster glass behavior. Further, the dc field\nsuperimposed on ac susceptibility and absence of memory effect in ac\nsusceptibility has suggested the existence of non interacting clusters\ncomprising of competing interactions below 38 K. Competing magnetic\ninteractions due to the presence of mixed valances and antisite disorder found\nto establish a reentered cluster glassy state in the nanoparticles."
    },
    {
        "anchor": "Direct in-situ observation of structural transition driven actuation in\n  VO2 utilizing electron transparent cantilevers: Direct imaging and quantification of actuation in nanostructures that undergo\nstructural phase transitions could advance our understanding of collective\nphenomena in the solid state. Here, we demonstrate visualization of structural\nphase transition induced actuation in a model correlated insulator vanadium\ndioxide by in-situ Fresnel contrast imaging of electron transparent\ncantilevers. We quantify abrupt, reversible cantilever motion occurring due to\nthe stress relaxation across the structural transition from monoclinic to\ntetragonal phase with increasing temperature. Deflections measured in such\nnanoscale cantilevers can be directly correlated with macroscopic stress\nmeasurements by wafer curvature studies as well as temperature dependent\nelectrical conduction allowing one to interrogate lattice dynamics across\nlength scales.",
        "positive": "Role of Magnetic Coupling in Photoluminescence Kinetics of Mn2+-doped\n  ZnS Nanoplatelets: Mn2+-doped semiconductor nanocrystals with tuned location and concentration\nof Mn2+ ions can yield diverse coupling regimes, which can highly influence\ntheir optical properties such as emission wavelength and photoluminescence (PL)\nlifetime. However, investigation on the relationship between the Mn2+\nconcentration and the optical properties is still challenging because of the\ncomplex interactions of Mn2+ ions and the host and between the Mn2+ ions. Here,\natomically flat ZnS nanoplatelets (NPLs) with uniform thickness were chosen as\nmatrixes for Mn2+ doping. Using time-resolved (TR) PL spectroscopy and density\nfunctional theory (DFT) calculations, a connection between coupling and PL\nkinetics of Mn2+ ions was established.\n  Moreover, it was found that the Mn2+ ions residing on the surface of a\nnanostructure produce emissive states and interfere with the change of\nproperties by Mn2+/Mn2+ coupling.\n  In a configuration with suppressed surface contribution to the optical\nresponse we show the underlying physical reasons for double and triple\nexponential decay by DFT methods. We believe that the presented doping strategy\nand simulation methodology of the Mn2+-doped ZnS system is a universal platform\nto study dopant location- and concentration-dependent properties also in other\nsemiconductors."
    },
    {
        "anchor": "Tuneable Correlated Disorder in Alloys: Understanding the role of disorder and the correlations that exist within it,\nis one of the defining challenges in contemporary materials science. However,\nthere are few material systems, devoid of other complex interactions, which can\nbe used to systematically study the effects of crystallographic conflict on\ncorrelated disorder. Here, we report extensive diffuse x-ray scattering studies\non the epitaxially stabilised alloy $\\mbox{U}_{1-x}\\mbox{Mo}_x$, showing that a\nnew form of intrinsically tuneable correlated disorder arises from a mismatch\nbetween the preferred symmetry of a crystallographic basis and the lattice upon\nwhich it is arranged. Furthermore, combining grazing incidence inelastic x-ray\nscattering and state-of-the-art ab initio molecular dynamics simulations we\ndiscover strong disorder-phonon coupling. This breaks global symmetry and\ndramatically suppresses phonon-lifetimes compared to alloying alone, providing\nan additional design strategy for phonon engineering. These findings have\nimplications wherever crystallographic conflict can be accommodated and may be\nexploited in the development of future functional materials.",
        "positive": "Structural composites for multifunctional applications: current\n  challenges and future trends: This review paper summarizes the current state-of-art and challenges for the\nfuture developments of fiber-reinforced composites for structural applications\nwith multifunctional capabilities. After a brief analysis of the reasons of the\nsuccessful incorporation of fiber-reinforced composites in many different\nindustrial sectors, the review analyzes three critical factors that will define\nthe future of composites. The first one is the application of novel\nfiber-deposition and preforming techniques together with innovative liquid\nmoulding strategies, which will be combined by optimization tools based on\nnovel multiscale modelling approaches, so fiber-reinforced composites with\noptimized properties can be designed and manufactured for each application. In\naddition, composite applications will be enhanced by the incorporation of\nmultifunctional capabilities. Among them, electrical conductivity, energy\nstorage (structural supercapacitors and batteries) and energy harvesting\n(piezoelectric and solar energy) seem to be the most promising ones."
    },
    {
        "anchor": "Topological transition in Pb1-xSnxSe using Meta-GGA: We calculate the mirror Chern number (MCN) and the band gap for the alloy\nPb1-xSnxSe as a function of the concentration x by using virtual crystalline\napproximation. We use the electronic structure from the relativistic density\nfunctional theory calculations in the Generalized-Gradient- Approximation (GGA)\nand meta-GGA approximation. Using the modified Becke-Johnson meta- GGA\nfunctional, our results are comparable with the available experimental data for\nthe MCN as well as for the band gap. We advise to use modified Becke-Johnson\napproximation with the parameter c=1.10 to describe the transition from trivial\nto topological phase for this class of compounds.",
        "positive": "Radial spin texture in elemental tellurium with chiral crystal structure: The chiral crystal is characterized by a lack of mirror symmetry and an\ninversion center, resulting in the inequivalent right- and left-handed\nstructures. In the noncentrosymmetric crystal structure, the spin and momentum\nof electrons are locked in the reciprocal space with the help of the spin-orbit\ninteraction. To reveal the spin textures of chiral crystals, here we\ninvestigate the spin and electronic structure in p-type semiconductor elemental\ntellurium with a chiral crystal structure by using spin- and angle-resolved\nphotoemission spectroscopy. Our data demonstrate that the highest valence band\ncrossing the Fermi level has a spin component parallel to the electron momentum\naround the BZ corners. Significantly, we have also confirmed that the spin\npolarization is reversed in the crystal with the opposite chirality. The\nresults indicate that the spin textures of the right- and left-handed chiral\ncrystals are hedgehog-like, leading to unconventional magnetoelectric effects\nand nonreciprocal phenomena."
    },
    {
        "anchor": "The characterization of Co-nanoparticles supported on graphene: The results of density functional theory (DFT) calculations and measurements\nof X-ray photoelectron (XPS) and X-ray emission (XES) spectra of\nCo-nanoparticles dispersed on graphene/Cu composites are presented. It is found\nthat for 0.02nm and 0.06nm Co coverage the Co atoms form islands which are\nstrongly oxidized under exposure at the air. For Co (2nm) coverage the upper\nCo-layers is oxidized whereas the lower layers contacting with graphene is in\nmetallic state. Therefore Co (2 nm) coverage induces the formation of\nprotective oxide layer providing the ferromagnetic properties of Co\nnanoparticles which can be used as spin filters in spintronics devices.",
        "positive": "Molecular-beam epitaxy of GaSb on 6{\\textdegree}-offcut (001) Si using a\n  GaAs nucleation layer: We studied and optimized the molecular beam epitaxy of GaSb layers on vicinal\n(001) Si substrates using a GaAs nucleation layer. An in-depth analysis of the\ndifferent growth stages under optimized conditions revealed the formation of a\nhigh density of small GaAs islands forming a quasi-two-dimensional layer. GaSb\nthen nucleated atop this layer as three-dimensional islands before turning to\ntwo-dimensional growth within a few nanometers. Moreover, reflexion high-energy\nelectron diffraction revealed a fast relaxation of GaAs on Si and of GaSb on\nGaAs. The GaSb layer quality was better than that of similar layers grown on Si\nthrough AlSb nucleation layers."
    },
    {
        "anchor": "First-principles study of the influence of (110) strain on the\n  ferroelectric trends of TiO$_2$: We investigate the impact of uniaxial strain on atomic shifts, dipolar\ninteractions, polarization and electric permittivity in TiO$_2$ (rutile) by\nusing two different implementations of density functional theory. It is shown\nthat calculations using the Vienna ab inito simulation package (VASP) and the\nplane-wave self-consistent field method (PWscf) yield qualitatively the same\natomic relaxations and ferroelectric trends under strain. The phonon dispersion\ncurves of unstrained and strained TiO$_2$ (rutile) obtained by employing the\nlinear response method confirm previous calculations of the giant LO-TO\nsplitting and the appearance of soft polar modes. A second order phase\ntransition into a ferroelectric phase with polarization along (110) appears\nunder expansive strain in (110) direction.",
        "positive": "Physical properties of Ce3-xTe4 below room temperature: The physical properties of polycrystalline Ce3-xTe4 were investigated by\nmeasurements of the thermoelectric properties, Hall coefficient, heat capacity,\nand magnetization. The fully-filled, metallic x=0 compound displays a soft\nferromagnetic transition near 4K, and analysis of the corresponding heat\ncapacity anomaly suggests a doublet ground state for Ce^{3+}. The transition is\nsuppressed to below 2K in the insulating x=0.33 composition, revealing that\nmagnetic order in Ce3-xTe4 is driven by an RKKY-type interaction. The\nthermoelectric properties trend with composition as expected from simple\nelectron counting, and the transport properties in Ce3Te4 are observed to be\nsimilar to those in La3Te4. Trends in the low temperature thermal conductivity\ndata reveal that the phonons are efficiently scattered by electrons, while all\ncompositions examined have a lattice thermal conductivity near 1.2W/m/K at\n200K."
    },
    {
        "anchor": "Circularly polarized resonant soft x-ray diffraction study of helical\n  magnetism in hexaferrite: Magnetic spiral structures can exhibit ferroelectric moments as recently\ndemonstrated in various multiferroic materials. In such cases the helicity of\nthe magnetic spiral is directly correlated with the direction of the\nferroelectric moment and measurement of the helicity of magnetic structures is\nof current interest. Soft x-ray resonant diffraction is particularly\nadvantageous because it combines element selectivity with a large magnetic\ncross-section. We calculate the polarization dependence of the resonant\nmagnetic x-ray cross-section (electric dipole transition) for the basal plane\nmagnetic spiral in hexaferrite Ba0.8Sr1.2Zn2Fe12O22 and deduce its domain\npopulation using circular polarized incident radiation. We demonstrate there is\na direct correlation between the diffracted radiation and the helicity of the\nmagnetic spiral.",
        "positive": "Two step solid state synthesis and Synchrotron X-ray characterizations\n  of ceramic Co3TeO6; an improper multiferroic: A two step solid state reaction route has been presented to synthesize\nmonophasic cobalt tellurate (Co3TeO6, CTO) using Co3O4 and TeO2 as starting\nreagents. During synthesis, initial ingredient Co3O4 is found better than CoO\nin circumventing the intermediate Co5TeO8 or CoTeO3 phases. High resolution\nSynchrotron X-ray Diffraction has been used to probe different phases present\nin synthesized CTO and to achieve its single phase. Further, XANES studies near\nCo K and Te L-edge reveal mixed oxidation states of Co (i.e. Co2+ and Co3+) and\n+VI valence state of Te respectively, which is also confirmed with XPS. Charge\nimbalance due to different oxidation states of the Co-ions has been observed to\nbe compensated by plausible Te-cations vacancy. Enhanced multiferroic\nproperties like effective magnetic moment (JAP 116, (2014)) have been\ncorrelated with the present synthesis route."
    },
    {
        "anchor": "Synthesis and structure of carbon doped H3S compounds at high pressure: Understanding of recently reported putative close-to-room-temperature\nsuperconductivity in C-S-H compounds at 267 GPa demands reproducible synthesis\nprotocol as well as knowledge of its structure and composition. We synthesized\nC-S-H compounds with various carbon composition at high pressures from\nelemental C and methane CH4, sulfur S, and molecular hydrogen H2. Here we focus\non compounds synthesized using methane as these allow a straightforward\ndetermination of their structure and composition by combining single-crystal\nX-ray diffraction (XRD) and Raman spectroscopy. We applied a two-stage\nsynthesis of ((CH4)x(H2S)(1-x))2H2 compounds by first reacting sulfur and mixed\nmethane-hydrogen fluids and forming CH4 doped H2S crystals at 0.5-3 GPa, and\nthen by growing single crystals of the desired hydrogen rich compound. Raman\nspectroscopy applied to this material shows the presence of the CH4 molecules\nincorporated into the lattice and allows to determine the CH4 content, while\nsingle-crystal X-ray diffraction results suggest that the methane molecules\nsubstitute H2S ones. The structural behavior of these compounds is very similar\nto the previously investigated methane free compounds demonstrating a\ntransition from Al2Cu type I4/mcm structure to a modulated structure at 20-30\nGPa and back to the same basic structure in an extended modification with\ngreatly modified Raman spectra. This latter phase demonstrates a distortion\ninto Pnma structure at 132-159 GPa and then transforms into a common Im-3m H3S\nphase at higher pressures, however, no structural anomaly is detected near 220\nGPa, where a sharp upturn in Tc has been reported.",
        "positive": "In-situ study of rules of nanostructure evolution, severe plastic\n  deformations, and friction under high pressure: Severe plastic deformations under high pressure are used to produce\nnanostructured materials but were studied ex-situ. We introduce rough diamond\nanvils to reach maximum friction equal to yield strength in shear and perform\nthe first in-situ study of the evolution of the pressure-dependent yield\nstrength and nanostructural parameters for severely pre-deformed Zr.\n{\\omega}-Zr behaves like perfectly plastic, isotropic, and\nstrain-path-independent. This is related to reaching steady values of the\ncrystallite size and dislocation density, which are pressure-, strain- and\nstrain-path-independent. However, steady states for {\\alpha}-Zr obtained with\nsmooth and rough anvils are different, which causes major challenge in\nplasticity theory."
    },
    {
        "anchor": "Field-theoretical approach to a dense polymer with an ideal binary\n  mixture of clustering centers: We propose a field-theoretical approach to a polymer system immersed in an\nideal mixture of clustering centers. The system contains several species of\nthese clustering centers with different functionality, each of which connects a\nfixed number segments of the chain to each other. The field-theory is solved\nusing the saddle point approximation and evaluated for dense polymer melts\nusing the Random Phase Approximation. We find a short-ranged effective\ninter-segment interaction with strength dependent on the average segment\ndensity and discuss the structure factor within this approximation. We also\ndetermine the fractions of linkers of the different functionalities.",
        "positive": "QH-POCC: taming tiling entropy in thermal expansion calculations of\n  disordered materials: Disordered materials are attracting considerable attention because of their\nenhanced properties compared to their ordered analogs, making them particularly\nsuitable for high-temperature applications. The feasibility of incorporating\nthese materials into new devices depends on a variety of thermophysical\nproperties. Among them, thermal expansion is critical to device stability,\nespecially in multi-component systems. Its calculation, however, is quite\nchallenging for materials with substitutional disorder, hindering computational\nscreenings. In this work, we introduce QH-POCC to leverage the local\ntile-expansion of disorder. This method provides an effective partial partition\nfunction to calculate thermomechanical properties of substitutionally\ndisordered compounds in the quasi-harmonic approximation. Two systems, AuCu3\nand CdMg3, the latter a candidate for long-period superstructures at low\ntemperature, are used to validate the methodology by comparing the calculated\nvalues of the coefficient of thermal expansion and isobaric heat capacity with\nexperiment, demonstrating that QH-POCC is a promising approach to study\nthermomechanical properties of disordered systems."
    },
    {
        "anchor": "Correlations between morphology, crystal structure and magnetization of\n  epitaxial cobalt-platinum films grown with pulsed laser ablation: The effects of growth rate (G_r), deposition temperature (T_d), film\nthickness (t_F), and substrate induced strain (epsilon) on morphological,\ncrystallographic and magnetic characteristics of equiatomic CoPt epitaxial\nfilms synthesized with PLD are investigated. The (001) substrates of MgO, STO\nand LAO provide different degree of epitaxial strain for growth of the\ndisordered face centered cubic (fcc) and ordered face centered tetragonal\n(L1_0) phases of CoPt. The films deposited at T_d~600 ^0C on all three\nsubstrates are fcc with in-plane magnetization and a narrow hysteresis loop of\nwidth~200 Oe. The L1_0 phase, stabilized only at T_d~700 ^0C becomes\npredominantly c-axis oriented as T_d is increased to 800 ^0C. While the\ncrystallographic structure of the films depends solely on the T_d, their\nmicrostructure and magnetization characteristics are decided by the growth\nrate. At the higher G_r (~1A/sec) the L1_0 films have a maze-like structure\nwhich converts to a continuous film as the t_F is increased from 20 to 50 nm.\nThe H_c of these films increases as the L1_0 phase fraction grows with T_d and\nits orientation becomes out of the film plane. The evolution of microstructure\nwith T_d is remarkably different at lower growth rate (~0.4A /sec). Here the\nstructure changes from a self-similar fractal pattern to an assembly of\nnano-dots as the T_d is raised from 700 to 800 ^0C, and is understood in terms\nof the imbalance between strain and interfacial energies. MFM of such films\nreveals no distinct domain walls within the nano-islands while a clear contrast\nis seen between the islands of reversed magnetization. The simple picture of\ncoherent rotation of moment appears incompatible with the time dependence of\nthe remanent magnetization in these films.",
        "positive": "Impurity induced spin gap asymmetry in nanoscale graphene: We propose a unique way to control both bandgap and the magnetic properties\nof nanoscale graphene, which might prove highly beneficial for application in\nnanoelectronic and spintronic devices. We have shown that chemical doping by\nnitrogen along a single zigzag edge breaks the sublattice symmetry of graphene.\nThis leads to the opening of a gap and a shift of the molecular orbitals\nlocalized on the doped edge in such a way that the spin gap asymmetry, which\ncan lead to half-metallicity under certain conditions, is obtained. The\nspin-selective behavior of graphene and tunable spin gaps help us to obtain\nsemiconductor diode-like current-voltage characteristics, where the current\nflowing in one direction is preferred over the other. The doping in the middle\nof the graphene layer results in an impurity level between the HOMO and LUMO\norbitals of pure graphene (again, much like in semiconductor systems) localized\non the zigzag edges thus decreasing the bandgap and adding unpaired electrons,\nand this can also be used to control graphene conductivity."
    },
    {
        "anchor": "Thermal squeezing and nonlinear spectral shift of magnons in\n  antiferromagnetic insulators: We investigate the effect of magnon-magnon interactions on the dispersion and\npolarization of magnons in collinear antiferromagnetic (AF) insulators at\nfinite temperatures. In two-sublattice AF systems with either uniaxial or\nbiaxial magnetocrystalline anisotropies, we implement a self-consistent\nHartree-Fock mean-field approximation to explore the nonlinear thermal\ninteractions. The resulting nonlinear magnon interactions separate into\ntwo-magnon intra- and interband scattering processes. Furthermore, we compute\nthe temperature dependence of the magnon bandgap and AF resonance modes due to\nnonlinear magnon interactions for square and hexagonal lattices. In addition,\nwe study the effect of magnon interactions on the polarization of magnon modes.\nWe find that although the noninteracting eigenmodes in the uniaxial case are\ncircularly polarized, but in the presence of nonlinear thermal interactions the\nlocal U(1) symmetry of the Hamiltonian is broken. The attractive nonlinear\ninteractions squeeze the low-energy magnon modes and make them elliptical. In\nthe biaxial case, on the other hand, the bare eigenmodes of low energy magnons\nare elliptically polarized but thermal nonlinear interactions squeeze them\nfurther. Direct measurements of the predicted temperature-dependent AF\nresonance modes and their polarization can be used as a tool to probe the\nnonlinear interactions. Our findings establish a framework for exploring the\neffect of thermal magnon interactions in technologically important magnetic\nsystems, such as magnetic stability of recently discovered two-dimensional\nmagnetic materials, coherent transport of magnons, Bose-Einstein condensation\nof magnons, and magnonic topological insulators.",
        "positive": "Towards Non-Volatile Spin Orbit Devices: Deposition of Ferroelectric\n  Hafnia on Monolayer Graphene/Co/HM Stacks: Although technologically challenging, the integration of ferroelectric thin\nfilms with graphene spintronics potentially allows the realization of highly\nefficient, electrically tuneable, non-volatile memories. Here, the atomic layer\ndeposition (ALD) of ferroelectric Hf$_{0.5}$Zr$_{0.5}$O$_2$ (HZO) directly on\ngraphene (Gr)/Co/heavy metal (HM) epitaxial stacks is investigated via the\nimplementation of several nucleation methods. With an in-situ method employing\nan Al$_2$O$_3$ layer, the HZO demonstrates a remanent polarization (2Pr) of\n19.2 $\\mu C/cm^2$. An ex-situ, naturally oxidized sputtered Ta layer for\nnucleation produces a film with 2Pr of 10.81 $\\mu C/cm^2$, but a lower coercive\nfield over the stack and switching enduring over subsequent cycles. Magnetic\nhysteresis measurements taken before and after ALD deposition show strong\nperpendicular magnetic anisotropy (PMA), with only slight deviations in the\nmagnetic coercive fields due to the HZO deposition process, thus pointing to a\ngood preservation of the single-layer Gr. X-ray diffraction measurements\nfurther confirm that the high-quality interfaces demonstrated in the stack\nremain unperturbed by the ferroelectric deposition and anneal."
    },
    {
        "anchor": "Excitation spectrum of hydrogen adsorbed to carbon nanotubes: We have studied the microscopic dynamics of hydrogen adsorbed to bundles of\nsingle walled carbon nanotubes using inelastic neutron scattering. Evidence is\nobtained for much higher storage capacities in chemically treated compared to\nas prepared material. This indicates an additional adsorption layer inside the\ntubes. Well pronounced excitations in the H2 spectrum at low energies confirm\nthis conclusion. The desorption of hydrogen is monitored in real time as a\nfunction of temperature. Hydrogen storage is highly stable below 150 K in\nagreement with the harmonic evolution of the hydrogen spectrum, which indicates\na strong binding potential. Above 200 K hydrogen can be released in a\ncontrolled way by simple heating. The excitation spectrum changes significantly\nduring the release. Remnants of hydrogen persist up to 400 K.",
        "positive": "Microdroplet Approach for Measuring Aqueous Solubility and Nucleation\n  Kinetics of a Metastable Polymorph: The case of KDP Phase IV: Solubility and interfacial energy are two fundamental parameters underlying\nthe competitive nucleation of polymorphs. However, solubility measurement of\nmetastable phases comes with a risk of solventmediated transformations which\ncan render the results unreliable. In this work, we present a rapid\nmicrofluidic technique for measuring aqueous solubility of the metastable form\nusing KDP Phase IV as a model system. This bracketing approach involves\nanalyzing the dissolution behavior of crystals in contact with supersaturated\nmicrodroplets generated via evaporation. Then, with the help of our recently\ndeveloped nucleation time measurement technique, together with Mersmann\ncalculation of interfacial energies from solubilities, we were able to access\nthe interfacial energies of both metastable and stable phases. To gain further\ninsights into the observed nucleation behavior, we employed the Classical\nNucleation Theory (CNT) to model the competition of polymorphs using our\nmeasured solubility and calculated interfacial energies. The results show that\nthe stable form is favored at lower supersaturation while the metastable form\nis favored at higher supersaturation, in good agreement with our observations\nand experimental reports in the literature. Overall, our microfluidic approach\nallows access to unprecedentedly deep levels of supersaturation and reveals an\ninteresting interplay between thermodynamics and kinetics in polymorphic\nnucleation. The experimental methods and insights presented herein can be of\ngreat interest, notably in the mineral processing and pharmaceutical industry."
    },
    {
        "anchor": "Charge Transfer Kinetics at the Solid-Solid Interface in Porous\n  Electrodes: Interfacial charge transfer is widely assumed to obey Butler-Volmer kinetics.\nFor certain liquid-solid interfaces, Marcus-Hush-Chidsey theory is more\naccurate and predictive, but it has not been applied to porous electrodes. Here\nwe report a simple method to extract the charge transfer rates in carbon-coated\nLiFePO4 porous electrodes from chronoamperometry experiments, obtaining curved\nTafel plots that contradict the Butler-Volmer equation but fit the\nMarcus-Hush-Chidsey prediction over a range of temperatures. The fitted\nreorganization energy matches the Born solvation energy for electron transfer\nfrom carbon to the iron redox site. The kinetics are thus limited by electron\ntransfer at the solid-solid (carbon-LixFePO4) interface, rather than by ion\ntransfer at the liquid-solid interface, as previously assumed. The proposed\nexperimental method generalizes Chidsey's method for phase-transforming\nparticles and porous electrodes, and the results show the need to incorporate\nMarcus kinetics in modeling batteries and other electrochemical systems.",
        "positive": "Atomistic simulations of thermodynamic properties of liquid gallium from\n  first principles: In the research of condensed matter, atomistic dynamic simulations play a\ncrucial role, particularly in revealing dynamic processes, phase transitions\nand thermodynamic statistics macroscopic physical properties in systems such as\nsolids and liquids. For a long time, simulating complex and disordered liquids\nhas been a challenge compared to ordered crystalline structures. The primary\nreasons for this challenge are the lack of precise force field functions and\nthe neglect of nuclear quantum effects. To overcome these two limits in\nsimulation of liquids, we use a deep potential (DP) with quantum thermal bath\n(QTB) approach. DP is a machine learning model are sampled from density\nfunctional theory and able to do large-scale atomic simulations with its\nprecision. QTB is a method which incorporates nuclear quantum effects by\nquantum fluctuation dissipation. The application of this first principles\napproach enable us to successfully describe the phase transition processes in\nsolid and liquid Gallium (Ga) as well as the associated dynamic phenomena. More\nimportantly, we obtain the thermodynamic properties of liquid Ga, such as\ninternal energy, specific heat, enthalpy change, entropy and Gibbs free energy,\nand these results align remarkably well with experiments. Our research has\nopened up a new paradigm for the study of dynamics and thermodynamics in\nliquids, amorphous materials, and other disordered systems, providing valuable\ninsights and references for future investigations."
    },
    {
        "anchor": "Role of bulk and surface phonons in the decay of metal surface states: We present a comprehensive theoretical investigation of the electron-phonon\ncontribution to the lifetime broadening of the surface states on Cu(111) and\nAg(111), in comparison with high-resolution photoemission results. The\ncalculations, including electron and phonon states of the bulk and the surface,\nresolve the relative importance of the Rayleigh mode, being dominant for the\nlifetime at small hole binding energies. Including the electron-electron\ninteraction, the theoretical results are in excellent agreement with the\nmeasured binding energy and temperature dependent lifetime broadening.",
        "positive": "Atomic ordering in self-assembled Ge:Si(001) islands observed by X-ray\n  scattering: X-ray diffuse scattering in the vicinity of a basis-forbidden (200) Bragg\nreflection was measured for a sample with uncapped self-assembled Ge islands\nepitaxially grown on Si(001). Our results provide evidence of atomically\nordered SiGe domains in both islands and wetting layer. The modeling of x-ray\nprofiles reveals the presence of antiphase boundaries separating the ordered\ndomains in a limited region of the islands where the stoichiometry is close to\nSi0.5Ge0.5."
    },
    {
        "anchor": "Experimental realization of purely excitonic lasing in ZnO microcrystals\n  at room temperature: transition from exciton-exciton to exciton-electron\n  scattering: Since the seminal observation of room-temperature laser emission from ZnO\nthin films and nanowires, numerous attempts have been carried out for detailed\nunderstanding of the lasing mechanism in ZnO. In spite of the extensive efforts\nperformed over the last decades, the origin of optical gain at room temperature\nis still a matter of considerable discussion,. We show that ZnO microcrystals\nwith a size of a few micrometers exhibit purely excitonic lasing at room\ntemperature without showing any symptoms of electron-hole plasma emission. We\nthen present the distinct experimental evidence that the room-temperature\nexcitonic lasing is achieved not by exciton-exciton scattering, as has been\ngenerally believed, but by exciton-electron scattering. As the temperature is\nlowered below ~150 K, the lasing mechanism is shifted from the exciton-electron\nscattering to the exciton-exciton scattering. We also argue that the ease of\ncarrier diffusion plays a significant role in showing room-temperature\nexcitonic lasing.",
        "positive": "Mechanical strain in capped and uncapped self-assembled Ge/Si quantum\n  dots: In this study we numerically calculate the spatial profile of mechanical\nstrain on self-assembled germanium (Ge) quantum dots (QDs) grown on a silicon\n(Si) substrate. Although the topic has been exhaustively studied, interesting\nfeatures have not been explained or even mentioned in the literature yet. We\nstudied the effect of the cap layer considering two cases: capped QDs (where a\nSi cap is present above the Ge QDs) and uncapped QDs (where no Si is present\nabove the Ge QDs). We observed that Ge in the capped QDs is more strained\ncompared with the the uncapped QDs. This expected effect is attributed to the\nadditional tension from the Si cap layer. However, the situation is opposite\nfor the Si substrate, it is more strained in the uncapped QD because the Ge\nlayer is less strained in this case. We also calculated the band-edge alignment\nfor the electrons and holes."
    },
    {
        "anchor": "The Transfer Matrix Method and The Theory of Finite Periodic Systems.\n  From Heterostructures to Superlattices: Long-period systems and superlattices, with additional periodicity, have new\neffects on the energy spectrum and wave functions. Most approaches adjust\ntheories for infinite systems, which is acceptable for large but not small\nnumber of unit cells $n$. In the past 30 years, a theory based entirely on\ntransfer matrices was developed, where the finiteness of $n$ is an essential\ncondition. The theory of finite periodic systems (TFPS) is also valid for any\nnumber of propagating modes, and arbitrary potential profiles (or refractive\nindices). We review this theory, the transfer matrix definition, symmetry\nproperties, group representations, and relations with the scattering\namplitudes. We summarize the derivation of multichannel matrix polynomials\n(which reduce to Chebyshev polynomials in the one-propagating mode limit), the\nanalytical formulas for resonant states, energy eigenvalues, eigenfunctions,\nparity symmetries, and discrete dispersion relations, for superlattices with\ndifferent confinement characteristics. After showing the inconsistencies and\nlimitations of hybrid approaches that combine the transfer-matrix method with\nFloquet's theorem, we review some applications of the TFPS to multichannel\nnegative resistance, ballistic transistors, channel coupling, spintronics,\nsuperluminal, and optical antimatter effects. We review two high-resolution\nexperiments using superlattices: tunneling time in photonic band-gap and\noptical response of blue-emitting diodes, and show extremely accurate\ntheoretical predictions.",
        "positive": "Superconductivity in SrB3C3 clathrate: We predict superconductivity for the carbon-boron clathrate SrB3C3 at 27-43 K\nfor Coulomb pseudopotential (mu*) values between 0.17 and 0.10 using\nfirst-principles calculations with conventional electron-phonon coupling.\nElectrical transport measurements, facilitated by a novel in situ experimental\ndesign compatible with extreme synthesis conditions (>3000 K at 50 GPa), show\nnon-hysteretic resistivity drops that track the calculated magnitude and\npressure dependence of superconductivity for mu*=0.15, and transport\nmeasurements collected under applied magnetic fields confirm superconductivity\nwith an onset Tc of approximately 20 K at 40 GPa. Carbon-based clathrates thus\nrepresent a new class of superconductors similar to other covalent metals like\nMgB2 and doped fullerenes. Carbon clathrates share structures similar to\nsuperconducting superhydrides, but covalent C-B bonds allow metastable\npersistence at ambient conditions."
    },
    {
        "anchor": "Factors correlating to enhanced surface diffusion in metallic glasses: The enhancement of surface diffusion (DS) over the bulk (DV) in metallic\nglasses (MGs) is well documented and likely to strongly influence the\nproperties of glasses grown by vapor deposition. Here, we use classical\nmolecular dynamics simulations to identify different factors influencing the\nenhancement of surface diffusion in MGs. MGs have a simple atomic structure and\nbelong to the category of moderately fragile glasses that undergo pronounced\nslowdown of bulk dynamics with cooling close to the glass transition\ntemperature (Tg). We observe that DS exhibits a much more moderate slowdown\ncompared to DV when approaching Tg, and DS/DV at Tg varies by two orders of\nmagnitude among the MGs investigated. We demonstrate that both the surface\nenergy and the fraction of missing bonds for surface atoms show good\ncorrelation to DS/DV, implying that the loss of nearest neighbors at the\nsurface directly translates into higher mobility, unlike the behavior of\nnetwork- and hydrogen-bonded organic glasses. Fragility, a measure of the\nslowdown of bulk dynamics close to Tg, also correlates to DS/DV, with more\nfragile systems having larger surface enhancement of mobility. The deviations\nobserved in the fragility and DS over DV relationship are shown to be\ncorrelated to the extent of segregation or depletion of the mobile element at\nthe surface. Finally, we explore the relationship between the diffusion\npre-exponential factor (D0) and activation energy (Q) and compare to a ln(D0)-Q\ncorrelation previously established for bulk glasses, demonstrating similar\ncorrelations from MD as in the experiments and that the surface and bulk have\nvery similar ln(D0)-Q correlations.",
        "positive": "Spin Polarization through A Molecular Junction Based on Nuclear Berry\n  Curvature Effects: We explore the effects of spin-orbit coupling on nuclear wave packet motion\nnear an out-of-equilibrium molecular junction, where nonzero Berry curvature\nemerges as the antisymmetric part of the electronic friction tensor. The\nexistence of nonzero Berry curvature mandates that different nuclear wave\npackets (associated with different electronic spin states) experience different\nnuclear Berry curvatures, i.e. different pseudo-magnetic fields. Furthermore,\nfor a generic, two-orbital two-lead model (representing the simplest molecular\njunction), we report significant spin polarization of the {\\em electronic}\ncurrent with decaying and oscillating signatures in the large voltage limit --\nall as a result of {\\em nuclear} motion. These results are consistent with\nmagnetic AFM chiral-induced spin selectivity experiments. Altogether, our\nresults highlight an essential role for Berry curvature in condensed phase\ndynamics, where spin separation survives dissipation to electron-hole pair\ncreation and emerges as one manifestation of nuclear Berry curvature."
    },
    {
        "anchor": "Distributed multipoles from a robust basis-space implementation of the\n  iterated stockholder atoms procedure: The recently developed iterated stockholder atoms (ISA) approach of\nLillestolen and Wheatley (Chem. Commun. {\\bf 2008}, 5909 (2008)) offers a\npowerful method for defining atoms in a molecule. However, the real-space\nalgorithm is known to converge very slowly, if at all. Here we present a\nrobust, basis-space algorithm of the ISA method and demonstrate its\napplicability on a variety of systems. We show that this algorithm exhibits\nrapid convergence (taking around 10--80 iterations) with the number of\niterations needed being unrelated to the system size or basis set used.\nFurther, we show that the multipole moments calculated using this basis-space\nISA method are as good as, or better than those obtained from Stone's\ndistributed multipole analysis (J. Chem. Theory Comput. {\\bf 1}, 1128 (2005) ),\nexhibiting better convergence properties and resulting in better behaved\npenetration energies. This can have significant consequences in the development\nof intermolecular interaction models.",
        "positive": "Exploration of the bright and dark exciton landscape and fine structure\n  of MoS$_2$ (using G$_0$W$_0$-BSE): Spectral ordering between dark and bright excitons in transition metal\ndichalcogenides is of increasing interest for optoelectronic applications.\nHowever, little is known about dark exciton energies and their binding\nenergies. We report the exciton landscape including momentum-forbidden dark\nexcitons of MoS$_{2}$ monolayer using single shot GW-Bethe Salpeter equation\n(G$_{0}$W$_{0}$-BSE) calculations. We find the lowest-energy exciton to be\nindirect at ($\\textrm K'_{v} \\rightarrow \\textrm K_{c}$) in agreement with\nrecent GdW-BSE calculations [2D Mater. 6, 035003 (2019)]. We also find that by\nlarge, dark exciton binding energies ($E_b$) scale with the quasiparticle\nenergies ($E_g$) according to the $E_b/E_g=0.25$ rule. Differences in exciton\nbinding energies are explained using an orbital theory."
    },
    {
        "anchor": "Real-time non-adiabatic dynamics in the one-dimensional Holstein model:\n  Trajectory-based vs exact methods: We benchmark a set of quantum-chemistry methods, including multitrajectory\nEhrenfest, fewest-switches surface-hopping, and multiconfigurational-Ehrenfest\ndynamics, against exact quantum-many-body techniques by studying real-time\ndynamics in the Holstein model. This is a paradigmatic model in condensed\nmatter theory incorporating a local coupling of electrons to Einstein phonons.\nFor the two-site and three-site Holstein model, we discuss the exact and\nquantum-chemistry methods in terms of the Born-Huang formalism, covering\ndifferent initial states, which either start on a single Born-Oppenheimer\nsurface, or with the electron localized to a single site. For extended systems\nwith up to 51 sites, we address both the physics of single Holstein polarons\nand the dynamics of charge-density waves at finite electron densities. For\nthese extended systems, we compare the quantum-chemistry methods to exact\ndynamics obtained from time-dependent density matrix renormalization group\ncalculations with local basis optimization (DMRG-LBO). We observe that the\nmultitrajectory Ehrenfest method, in general, only captures the ultrashort time\ndynamics accurately. In contrast, the surface-hopping method with suitable\ncorrections provides a much better description of the long-time behavior but\nstruggles with the short-time description of coherences between different\nBorn-Oppenheimer states. We show that the multiconfigurational Ehrenfest method\nyields a significant improvement over the multitrajectory Ehrenfest method and\ncan be converged to the exact results in small systems with moderate\ncomputational efforts. We further observe that for extended systems, this\nconvergence is slower with respect to the number of configurations. Our\nbenchmark study demonstrates that DMRG-LBO is a useful tool for assessing the\nquality of the quantum-chemistry methods.",
        "positive": "Defect entropies and enthalpies in Barium Fluoride: Various experimental techniques, have revealed that the predominant intrinsic\npoint defects in BaF$_2$ are anion Frenkel defects. Their formation enthalpy\nand entropy as well as the corresponding parameters for the fluorine vacancy\nand fluorine interstitial motion have been determined. In addition, low\ntemperature dielectric relaxation measurements in BaF$_2$ doped with uranium\nleads to the parameters {\\tau}$_0$, E in the Arrhenius relation\n{\\tau}={\\tau}$_0$exp(E/kBT) for the relaxation time {\\tau}. For the relaxation\npeak associated with a single tetravalent uranium, the migration entropy\ndeduced from the pre-exponential factor {\\tau}$_0$, is smaller than the anion\nFrenkel defect formation entropy by almost two orders of magnitude. We show\nthat, despite their great variation, the defect entropies and enthalpies are\ninterconnected through a model based on anharmonic properties of the bulk\nmaterial that have been recently studied by employing density-functional theory\nand density-functional perturbation theory."
    },
    {
        "anchor": "High Pressure Structural Stability, and Optical Properties of Scheelite\n  type ZrGeO$_4$ and HfGeO$_4$ X-ray Phosphor Hosts: \\emph{Ab-initio} calculations were performed on the scheelite type MGeO$_4$\n(M = Hf, and Zr) compounds which find wide range of applications such as in\nx-ray imaging. We have studied the high pressure structural stability, elastic\nconstants, electronic structure and optical properties of these compounds\nthrough density functional theory calculations. Two different density\nfunctional approaches namely plane wave pseudopotential method (PW-PP) and full\npotential linearized augmented plane wave method (FP-LAPW) were used for the\npresent study. The ground state structural and vibrational properties are\ncalculated and found to be in good agreement with experimental data. The\ncompressibility of Zr and Hf germanates is found to be anisotropic as the\na-axis is less compressible over c-axis due to the presence of Ge-O bonds along\na-axis which is further confirmed from the ordering of the elastic constants\nthat follows C$_{11}$ $>$ C$_{33}$. The electronic structure of the compounds\nhas been calculated through recently developed Tran Blaha-modified Becke\nJohnson potential. The calculated electronic structure shows that the compounds\nare insulators with a gap of 5.39 eV for ZrGeO$_4$ and 6.25 eV for HfGeO$_4$\nrespectively. Optical anisotropy of these compounds are revealed from the\ncomputed optical properties such as complex dielectric function, refractive\nindex, and absorption coefficient. In addition, it is observed that Ti doped\nZrGeO$_4$ and HfGeO$_4$ turns out to be a good phosphor as the pristine\ncompounds have the energy gap greater than the visible range upon Ti doping\nbandgap reduces as a result emission spectra occurs in the visible region and\nis well explained in the present study.",
        "positive": "Pyroelectric response of ferroelectric nanoparticles: size effect and\n  electric energy harvesting: The size effect on pyroelectric response of ferroelectric nanowires and\nnanotubes is analyzed. The pyroelectric coefficient strongly increases with the\nwire radius decrease and diverges at critical radius Rcr corresponding to the\nsize-driven transition into paraelectric phase. Size-driven enhancement of\npyroelectric coupling leads to the giant pyroelectric current and voltage\ngeneration by the polarized ferroelectric nanoparticles in response to the\ntemperature fluctuation. The maximum efficiency of the pyroelectric energy\nharvesting and bolometric detection is derived, and is shown to approach the\nCarnot limit for low temperatures."
    },
    {
        "anchor": "Nanoscale brittle-to-ductile transition of the C15 CaAl$_2$ Laves phase: The influence of temperature on the deformation behaviour of the C15 CaAl$_2$\nLaves phase, a key constituent for enhancing the mechanical properties of Mg\nalloys up to service temperatures of 200 {\\deg}C, remains largely unexplored.\nThis study presents, for the first time, the nanoscale brittle-to-ductile\ntransition (BDT) of this intermetallic phase through in situ testing including\nnanoindentation, scratch testing, and micropillar splitting conducted at\nelevated temperatures. By correlating observations from these techniques,\nchanges in deformation of CaAl$_2$ were identified in relation to temperature.\nHigh-temperature nanoindentation quantitatively determined the temperature\nrange for the BDT, and revealed that CaAl$_2$ undergoes a BDT at ~0.55T$_m$,\nexhibiting an intermediate region of microplasticity. A noticeable decrease in\nnanoindentation hardness was observed at ~450-500 {\\deg}C, accompanied by an\nincrease in residual indent size, while indentation cracking was not observed\nabove 300 {\\deg}C. Results from high-temperature micropillar splitting revealed\ncracking and brittle pillar splitting up to 300 {\\deg}C, with an increase in\napparent fracture toughness from 0.9 $\\pm$ 0.1 MPa$\\cdot\\sqrt m$ to 2.8 $\\pm$\n0.3 MPa$\\cdot\\sqrt m$, and subsequent crack-free plastic deformation from 400\n{\\deg}C. Transmission electron microscopy analysis of the deformed material\nfrom nanoindentation revealed that the BDT of CaAl$_2$ may be attributed to\nenhanced dislocation plasticity with increasing temperature.",
        "positive": "Crystal structure, local structure, and defect structure of Pr-doped\n  SrTiO$_3$: X-ray diffraction studies showed that the structure of\n(Sr$_{1-x}$Pr$_x$)TiO$_3$ solid solutions at 300 K changes from the cubic\n$Pm3m$ to the tetragonal $I4/mcm$ with increasing $x$. The analysis of XANES\nand EXAFS spectra of the solid solutions revealed that Pr ions are\npredominantly in the 3+ oxidation state, they substitute for Sr atoms and are\non-center regardless of the preparation conditions. The weak dependence of the\nlattice parameter in (Sr$_{1-x}$Pr$_x$)TiO$_3$ on the Pr concentration was\nexplained by the competition between the relaxation of the Sr--O bond length,\nwhich results from the difference in ionic radii of Sr and Pr ions, and the\nrepulsion of positively charged Pr$^{3+}$ and Ti$^{4+}$ ions. It was shown that\nthe most important defects in the crystals are charged Sr vacancies and SrO\nplanar faults; praseodymium does not enter the Sr sites in the planar faults."
    },
    {
        "anchor": "Scaled indium oxide transistors fabricated using atomic layer deposition: In order to continue to improve integrated circuit performance and\nfunctionality, scaled transistors with short channel lengths and low thickness\nare needed. But the further scaling of silicon-based devices and the\ndevelopment of alternative semiconductor channel materials that are compatible\nwith current fabrication processes is challenging. Here we report\natomic-layer-deposited indium oxide transistors with channel lengths down to 8\nnm, channel thicknesses down to 0.5 nm and equivalent dielectric oxide\nthickness down to 0.84 nm. Due to the scaled device dimensions and low contact\nresistance, the devices exhibit high on-state currents of 3.1 A/mm at a drain\nvoltage of 0.5 V and a transconductance of 1.5 S/mm at a drain voltage 1 V. Our\ndevices are a promising alternative channel material for scaled transistors\nwith back-end-of-line processing compatibility.",
        "positive": "Alloy inhomogeneity and carrier localization in AlGaN sections and\n  AlGaN/AlN nanodisks in nanowires with 240-350 nm emission: The Al-Ga intermixing at Al(Ga)N/GaN interfaces in nanowires and the chemical\ninhomogeneity in AlxGa1-xN/AlN nanodisks (NDs) are attributed to the strain\nrelaxation process. This interpretation is supported by the three-dimensional\nstrain distribution calculated by minimizing the elastic energy in the\nstructure. The alloy inhomogeneity increases with Al content, leading to\nenhanced carrier localization signatures in their optical characteristics i.e.\nred shift of the emission, s-shaped temperature dependence and linewidth\nbroadening. Despite these alloy fluctuations, the emission energy of AlGaN/AlN\nNDs can be tuned in the 240-350 nm range with internal quantum efficiencies\naround 30%."
    },
    {
        "anchor": "Remarkably enhanced Curie temperature in monolayer CrI3 by hydrogen and\n  oxygen adsorption: A first-principles calculations: wo-dimensional (2D) materials unique properties and their promising\napplications in post-silicon microelectronics have attracted significant\nattention in the past decade. Recently, ferromagnetic order with out-of-plane\neasy axis in a monolayer of CrI3 has been observed and reported, with a Curie\ntemperature of 45 K. Here we study, using density functional theory (DFT)\ncalculations, how hydrogen and oxygen adsorption affects the structural,\nelectronic, and magnetic properties of a CrI3 monolayer. Our results show that\nwhile the structure remains almost unchanged by the adsorption of hydrogen,\nadsorption of oxygen completely distorts it. We have also found that both the\nadsorption of hydrogen and oxygen atoms significantly influences the electronic\nand magnetic properties of the monolayer. While hydrogen quenches the magnetic\nmoments of Cr atoms, oxygen introduces an impurity band in the gap.\nInterestingly, we find a strong enhancement of the Curie temperature by full\nhydrogenation, while the results are not conclusive for O. This result suggests\na simple and effective approach to manipulate the electronic and magnetic\nproperties of 2D magnets for spintronics applications.",
        "positive": "Diffusion Quantum Monte Carlo Study of Martensitic Phase Transition: The\n  Case of Phosphorene: Recent technical advances in dealing with finite-size errors make quantum\nMonte Carlo methods quite appealing for treating extended systems in electronic\nstructure calculations, especially when commonly-used density functional theory\n(DFT) methods might not be satisfactory. We present a theoretical study of\nmartensitic phase transition of a two-dimensional phosphorene by employing\ndiffusion Monte Carlo (DMC) approach to investigate the energetics of this\nphase transition. The DMC calculation supports DFT prediction of having a\nrather diffusive barrier that is characterized by having two transition states,\nin addition to confirming that the so-called black and blue phases of\nphosphorene are essentially degenerate. At the same time, the calculation shows\nthe importance of treating correlation energy accurately for describing the\nenergy changes in the martensitic phase transition, as is already widely\nappreciated for chemical bond formation/dissociation. Building on the atomistic\ncharacterization of the phase transition process, we also discuss how\nmechanical strain influences the stabilities of the two phases of phosphorene."
    },
    {
        "anchor": "Engineering One-Dimensional Quantum Stripes from Superlattices of\n  Two-Dimensional Layered Materials: One-dimensional (1D) quantum systems, which are predicted to exhibit novel\nstates of matter in theory, have been elusive in experiment. Here we report a\nsuperlattice method of creating artificial 1D quantum stripes, which offers\ndimensional tunability from two- to one-dimensions. As a model system, we have\nfabricated 1D iridium (Ir) stripes using a-axis oriented superlattices of a\nrelativistic Mott insulator Sr2IrO4 and a wide bandgap insulator LaSrGaO4, both\nof which are crystals with layered structure. In addition to the successful\nformation of 1D Ir-stripe structure, we have observed 1D quantum-confined\nelectronic states from optical spectroscopy and resonant inelastic x-ray\nscattering. Since this 1D superlattice approach can be applied to a wide range\nof layered materials, it opens a new era of 1D science.",
        "positive": "Ordering of droplets and light scattering in polymer dispersed liquid\n  crystal films: We study the effects of droplet ordering in initial optical transmittance\nthrough polymer dispersed liquid crystal (PDLC) films prepared in the presence\nof an electrical field. The experimental data are interpreted by using a\ntheoretical approach to light scattering in PDLC films that explicitly relates\noptical transmittance and the order parameters characterizing both the\norientational structures inside bipolar droplets and orientational distribution\nof the droplets. The theory relies on the Rayleigh-Gans approximation and uses\nthe Percus-Yevick approximation to take into account the effects due to droplet\npositional correlations."
    },
    {
        "anchor": "Measurement of the complex dielectric constant of a single gold\n  nanoparticle: A differential interference contrast microscopy technique, which employs a\nphotonic crystal fiber as a white-light source, is used to measure both the\nreal and imaginary parts of the complex dielectric constant of single 10 and 15\nnm gold nanoparticles over a wavelength range of 480 to 610 nm. Noticeable\ndeviations from bulk gold measurements are observed at short wavelengths and\nfor individual particles even after taking into account finite-size surface\ndamping effects.",
        "positive": "EPR studies of manganese centers in SrTiO3: Non-Kramers Mn3+ ions and\n  spin-spin coupled Mn4+ dimers: X- and Q-band electron paramagnetic resonance (EPR) study is reported on the\nSrTiO3 single crystals doped with 0.5-at.% MnO. EPR spectra originating from\nthe S = 2 ground state of Mn3+ ions are shown to belong to the three distinct\ntypes of Jahn-Teller centres. The ordering of the oxygen vacancies due to the\nreduction treatment of the samples and consequent formation of oxygen vacancy\nassociated Mn3+ centres are explained in terms of the localized charge\ncompensation. The EPR spectra of SrTiO3: Mn crystals show the presence of next\nnearest neighbor exchange coupled Mn4+ pairs in the <110> directions."
    },
    {
        "anchor": "Does a glycine sodium nitrite crystal exist?: The glycine sodium nitrite crystal reported by Khandpekar and Pati in the\npaper entitled, Synthesis and characterisation of glycine sodium nitrite\ncrystals having non linear optical behaviour, Opt Commun 285, 2012 288-293 is\nactually gamma-glycine. In addition, we show that glycine barium ammonium\nnitrate, glycine sodium zinc sulfate, glycine barium calcium nitrate, glycine\nacetamide and glycine dimer are dubious crystals.",
        "positive": "Temperature dependent creation of nitrogen-vacancy centers in CVD\n  diamond layers: In this work, we explore the ability of plasma assisted chemical vapor\ndeposition (PACVD) operating under high power densities to produce thin\nhigh-quality diamond layers with a controlled doping with negatively-charged\nnitrogen-vacancy (NV-) centers. This luminescent defect possesses specific\nphysical characteristics that make it suitable as an addressable solid-state\nelectron spin for measuring magnetic fields with unprecedented sensitivity. To\nthis aim, a relatively large number of NV- centers (> 10^12 cm^-3) should\nideally be located in a thin diamond layer (a few tens of nm) close to the\nsurface which is particularly challenging to achieve with the PACVD technique.\nHere we show that intentional temperature variations can be exploited to tune\nNV- creation efficiency during growth, allowing engineering complex stacking\nstructures with a variable doping. Because such a temperature variation can be\nperformed quickly and without any change of the gas phase composition, thin\nlayers can be grown. Measurements show that despite the temperature variations,\nthe luminescent centers incorporated using this technique exhibit spin\ncoherence properties similar to those reached in ultra-pure bulk crystals,\nwhich suggests that they could be successfully employed in magnetometry\napplications."
    },
    {
        "anchor": "First principles study of ferroelastic twins in halide perovskites: We present an ab initio simulation of $90^{\\circ}$ ferroelastic twins that\nwere recently observed in methyl ammonium lead iodide. There are two\ninequivalent types of $90^{\\circ}$ walls that we calculate to act as either\nelectron or hole sinks which suggests a possible route to enhancing charge\ncarrier separation in photovoltaic devices. Despite separating non-polar\ndomains, we show these walls to have a substantial in-plane polarisation of\n$\\sim 6 \\phantom{|} \\mu \\text{C}\\phantom{|}\\text{cm}^{-2}$, due in part to\nflexoelectricity. We suggest this in turn could allow for the photoferroic\neffect and create efficient pathways for photocurrents within the wall.",
        "positive": "Importance of bulk states for the electronic structure of semiconductor\n  surfaces: implications for finite slabs: We investigate the influence of slab thickness on the electronic structure of\nthe Si(100)-p(2x2) surface in density functional theory (DFT) calculations,\nconsidering both density of states and band structure. Our calculations, with\nslab thicknesses of up to 78 atomic layers, reveal that the slab thickness\nprofoundly affects the surface band structure, particularly the dangling bond\nstates of the silicon dimers near the Fermi level. We find that, to precisely\nreproduce the surface bands, the slab thickness needs to be large enough to\ncompletely converge the bulk bands in the slab. In case of the Si(100) surface,\nthe dispersion features of the surface bands, such as the band shape and width,\nconverge when the slab thickness is larger than 30 layers. Complete convergence\nof both the surface and bulk bands in the slab is only achieved when the slab\nthickness is greater than 60 layers."
    },
    {
        "anchor": "Energy distribution and quantum yield for photoemission from\n  air-contaminated gold surfaces under UV illumination close to the threshold: The kinetic energy distributions of photo-electrons emitted from gold\nsurfaces under illumination by UV-light close to the threshold are measured and\nanalyzed. Samples are prepared as chemically clean through Ar-Ion sputtering\nand then exposed to atmosphere for variable durations before Quantum Yield\nmeasurements are performed after evacuation. During measurements the bias\nvoltage applied to the sample is varied and the resulting emission current\nmeasured. Taking the derivative of the current-voltage curve yields the energy\ndistribution which is found to closely resemble the distribution of total\nenergies derived by DuBridge for emission from a free electron gas. We\ninvestigate the dependence of distribution shape and width on electrode\ngeometry and contaminant substances adsorbed from the atmosphere, in particular\nto water and hydro-carbons. Emission efficiency increases initially during air\nexposure before diminishing to zero on a timescale of several hours, whilst\nsubsequent annealing of the sample restores emissivity. A model fit function,\nin good quantitative agreement with the measured data, is introduced which\naccounts for the experiment-specific electrode geometry and an energy dependent\ntransmission coefficient. The impact of large patch potential fields from\ncontact potential drops between sample and sample holder is investigated. The\ntotal quantum yield is split into bulk and surface contributions which are\ntested for their sensitivity to light incidence angle and polarization. Our\nresults are directly applicable to model parameters for the contact-free\ndischarge system onboard the LISA Pathfinder spacecraft.",
        "positive": "High-Pressure Laser Floating Zone Furnace: The floating zone technique is a well-established single crystal growth\nmethod in materials research, able to produce volumetrically large specimens\nwith extremely high purities. However, traditional furnace designs have relied\non heating from high-powered bulb sources in combination with parabolic\nmirrors, and hence are constrained to transparent growth chambers with large\nsolid angles of optical access. This results in a stark limitation on\nachievable processing gas pressures, and in turn renders a range of compounds\nunsuitable for crystal growth by the floating zone technique, either due to\nexcessive volatility or due to metastability. Here, we demonstrate a novel\nhigh-pressure laser-based floating zone system (HP-LFZ). The use of lasers for\nheating allows implementation of a high-strength metal growth chamber,\npermitting greatly enhanced processing pressures over conventional mirror-based\ndesigns, with the current design allowing for pressures up to 1000 bar. We\ndemonstrate a series of example single crystal growths using this design in\npressures up to 675 bar, a significant increase over processing pressures\nattainable in commercially available floating zone systems. The general utility\nof the HP-LFZ is also illustrated via growths of a range of complex oxides."
    },
    {
        "anchor": "How do defects limit the ultrahigh thermal conductivity of BAs? A first\n  principles study: The promise enabled by BAs high thermal conductivity in power electronics\ncannot be assessed without taking into account the reduction incurred when\ndoping the material. Using first principles calculations, we determine the\nthermal conductivity reduction induced by different group IV impurities in BAs\nas a function of concentration and charge state. We unveil a general trend,\nwhere neutral impurities scatter phonons more strongly than the charged ones.\n$\\text{C}_{\\text{B}}$ and $\\text{Ge}_{\\text{As}}$ impurities show by far the\nweakest phonon scattering and retain BAs $\\kappa$ values of over $\\sim$ 1000\n$\\text{W}\\cdot\\text{K}^{-1}\\cdot\\text{m}^{-1}$ even up to high densities making\nthem ideal n-type and p-type dopants. Furthermore, going beyond the doping\ncompensation threshold associated to Fermi level pinning triggers observable\nchanges in the thermal conductivity. This informs design considerations on the\ndoping of BAs, and it also suggests a direct way to determine the onset of\ncompensation doping in experimental samples.",
        "positive": "Dynamic control of ferroionic states in ferroelectric nanoparticles: The polar states of uniaxial ferroelectric nanoparticles interacting with a\nsurface system of electronic and ionic charges with a broad distribution of\nmobilities is explored, which corresponds to the experimental case of\nnanoparticles in solution or ambient conditions. The nonlinear interactions\nbetween the ferroelectric dipoles and surface charges with slow relaxation\ndynamics in an external field lead to the emergence of a broad range of\nparaelectric-like, antiferroelectric-like ionic, and ferroelectric-like\nferroionic states. The crossover between these states can be controlled not\nonly by the static characteristics of the surface charges, but also by their\nrelaxation dynamics in the applied field. Obtained results are not only\npromising for advanced applications of ferroelectric nanoparticles in\nnanoelectronics and optoelectronics, they also offer strategies for\nexperimental verification."
    },
    {
        "anchor": "Quasi-molecular and atomic phases of dense solid hydrogen: The high-pressure phases of solid hydrogen are of fundamental interest and\nrelevant to the interior of giant planets; however, knowledge of these phases\nis far from complete. Particle swarm optimization (PSO) techniques were applied\nto a structural search, yielding hitherto unexpected high-pressure phases of\nsolid hydrogen at pressures up to 5 TPa. An exotic quasi-molecular mC24\nstructure (space group C2/c, stable at 0.47-0.59 TPa) with two types of\nintramolecular bonds was predicted, providing a deeper understanding of\nmolecular dissociation in solid hydrogen, which has been a mystery for decades.\nWe further predicted the existence of two atomic phases: (i) the oC12 structure\n(space group Cmcm, stable at > 2.1 TPa), consisting of planar H3 clusters, and\n(ii) the cI16 structure, previously observed in lithium and sodium, stable\nabove 3.5 TPa upon consideration of the zero-point energy. This work clearly\nrevised the known zero-temperature and high-pressure (>0.47 TPa) phase diagram\nfor solid hydrogen and has implications for the constituent structures of giant\nplanets.",
        "positive": "Slippery paraelectric transition metal dichalcogenide bilayers: Traditional ferroelectrics undergo thermally-induced phase transitions\nwhereby their structural symmetry increases. The associated higher-symmetry\nstructure is dubbed {\\em paraelectric}. Ferroelectric transition metal\ndichalcogenide bilayers have been recently shown to become paraelectric, but\nnot much has been said of the atomistic configuration of such a phase. As\ndiscovered through numerical calculations that include molecular dynamics here,\ntheir paraelectricity can only be ascribed to a time average of ferroelectric\nphases with opposing intrinsic polarizations, whose switching requires\nmacroscopically large areas to slip in unison."
    },
    {
        "anchor": "Effect of isothermal holding temperature on the precipitation hardening\n  in Vanadium-microalloyed steels with varying carbon and nitrogen levels: Combined effect of Carbon and Nitrogen levels and isothermal holding\ntemperature on the microstructure, precipitation and the tensile properties of\nVanadium microalloyed steels with 0.05 weight percent Vanadium were studied.\nTwo different Vanadium steels, one having higher Carbon and lower Nitrogen\ncontent, HCLN steel, and the other having lower Carbon and higher Nitrogen\ncontent, LCHN steel, were prepared and subjected to isothermal holding\ntreatment over a temperature range of 500 to 750 degree Celsius, after\nhot-deformation. Maximum precipitation strengthening from fine Vanadium\ncarbonitride precipitates has been found at intermediate isothermal holding\ntemperatures i.e. 600 to 650 degree Celsius in both the steels. In spite of the\nsignificantly smaller fraction of pearlite and bainite, coarser average ferrite\ngrain size and lower interaction of precipitation and dislocation in the\nferrite matrix, the yield strength of LCHN steel was close to HCLN steel. This\ncan be attributed to the higher precipitation strengthening ranging from 20 to\n50 MPa resulted from the finer Vanadium precipitates in LCHN steel than that of\nHCLN steel.",
        "positive": "General aspects of the vapor growth of semiconductor crystals - a study\n  based on DFT simulations of the NH3/NH2 covered GaN(0001) surface in hydrogen\n  ambient: Vapor growth of semiconductors is analyzed using recently obtained dependence\nof the adsorption energy on the electron charge transfer between the surface\nadsorbed species and the bulk [Krukowski et al. J. Appl. Phys. 114 (2013)\n063507, Kempisty et al. ArXiv 1307.5778 (2013)]. Ab initio calculations were\nperformed to study the physical properties of GaN(0001) surface in ammonia-rich\nconditions, i.e. covered by mixture of NH3 molecules and NH2 radicals. The\nFermi level is pinned at valence band maximum (VBM) and conduction band minimum\n(CBM) for full coverage by NH3 molecules and NH2 radicals, respectively. For\nthe crossover content of ammonia of about 25% monolayer (ML), the Fermi level\nis unpinned. It was shown that hydrogen adsorption energy depends on the doping\nin the bulk for the unpinned Fermi level, i.e. for this coverage. Surface\nstructure thermodynamic and mechanical stability criteria are defined and\ncompared. Mechanical stability of the coverage of such surfaces was checked by\ndetermination of the desorption energy of hydrogen molecules. Thermodynamic\nstability analysis indicates that initally equilibrium hydrogen vapor partial\npressure steeply increases with NH3 content to attain the crossover NH3/NH2\ncoverage, i.e. the unpinned Fermi level condition. For such condition the\nentire range of experimentally accessible pressures belongs showing that vapor\ngrowth of semiconductor crystals occurs predominantly for unpinned Fermi level\nat the surface, i.e. for flat bands. Accordingly, adsorption energy of most\nspecies depends on the doping in the bulk that is basis of the possible\nmolecular scenario explaining dependence of the growth and the doping of\nsemiconductor crystals on the doping in the bulk"
    },
    {
        "anchor": "Effect of Electron-Phonon Interaction and Ionized Impurity Scattering on\n  the Room Temperature Thermoelectric Properties of Bulk $MoSe_2$: We study the thermoelectric properties of bulk $MoSe_2$ within relaxation\ntime approximation including electron-phonon and ionized impurity interactions\nusing first-principles calculations at room temperatures. The anisotropy of\nthis two-dimensional layered metal dichalcogenide is studied by calculations of\nelectron mobility in the cross-plane and the in-plane directions. We show that\nthe cross-plane mobility is two orders of magnitude smaller than the in-plane\none. The inclusion of van der Waals interactions further lowers the carrier\nmobility in the cross-plane direction but minimally affects the in-plane one.\nThe results for in-plane electrical mobility and conductivity are in close\nagreement with experimentally reported values indicating the accuracy of the\ncalculations. The Seebeck coefficient calculations show that this coefficient\nis primarily dictated by the band structure. The details of relaxation times\nand inclusion of van der Waals interactions only slightly change the Seebeck\ncoefficient. The in-plane thermoelectric power factor reaches a maximum value\nof 20 $\\mu Wcm^{-1}K^{-2}$ at a carrier concentration of $1.5x10^{20}$\n$cm^{-3}$ at 300K.",
        "positive": "Correlation effects for semiconducting single wall carbon nanotube: a\n  density matrix renormalization group study: In this paper, we report the applicability of the density matrix\nrenormalization group(DMRG) approach to the cylindrical single wall carbon\nnanotube (SWCN) for purpose of its correlation effect. By applying the DMRG\napproach to the $t$+$U$+$V$ model, with $t$ and $V$ being the hopping and\nCoulomb energies between the nearest neighboring sites, respectively, and $U$\nthe onsite Coulomb energy, we calculate the phase diagram for the SWCN with\nchiral numbers ($n_{1}=3, n_{2}=2$), which reflects the competition between the\ncorrelation energy $U$ and $V$. Within reasonable parameter ranges, we\ninvestigate possible correlated groundstates, the lowest excitations and the\ncorresponding correlation functions in which the connection with the excitonic\ninsulator is particularly addressed."
    },
    {
        "anchor": "Wafer-scale selective area growth of GaN hexagonal prismatic\n  nanostructures on c-sapphire substrate: Selective area growth of GaN nanostructures has been performed on full 2\"\nc-sapphire substrates using Si3N4 mask patterned by nanoimprint lithography\n(array of 400 nm diameter circular holes). A new process has been developed to\nimprove the homogeneity of the nucleation selectivity of c-oriented hexagonal\nprismatic nanostructures at high temperature (1040\\circ C). It consists of an\ninitial GaN nucleation step at 950 \\circ C followed by ammonia annealing before\nhigh temperature growth. Structural analyses show that GaN nanostructures are\ngrown in epitaxy with c-sapphire with lateral overgrowths on the mask. Strain\nand dislocations are observed at the interface due to the large GaN/sapphire\nlattice mismatch in contrast with the high quality of the relaxed crystals in\nthe lateral overgrowth area. A cathodoluminescence study as a function of the\nGaN nanostructure size confirms these observations: the lateral overgrowth of\nGaN nanostructures has a low defect density and exhibits a stronger near band\nedge (NBE) emission than the crystal in direct epitaxy with sapphire. The shift\nof the NBE positions versus nanostructure size can be mainly attributed to a\ncombination of compressive strain and silicon doping coming from surface mask\ndiffusion.",
        "positive": "Tunneling anisotropic magnetoresistance of NiFe/IrMn/MgO/Pt stack: An\n  antiferromagnet based spin-valve: Spin-valve is a microelectronic device in which high and low resistance\nstates are realized by utilizing both charge and spin of carriers. Spin-valve\nstructures used in modern hard drive read-heads and magnetic random access\nmemories comprise two ferromagnetic (FM) electrodes whose relative\nmagnetization orientations can be switched between parallel and antiparallel\nconfigurations, yielding the desired giant or tunneling magnetoresistance\neffect. In this paper we demonstrate >100$% spin-valve-like signal in a\nNiFe/IrMn/MgO/Pt stack with an antiferromagnet (AFM) on one side and a\nnon-magnetic metal on the other side of the tunnel barrier. FM moments in NiFe\nare reversed by external fields <50mT and the exchange-spring effect of NiFe on\nIrMn induces rotation of AFM moments in IrMn which is detected by the measured\ntunneling anisotropic magnetoresistance (TAMR). Our work demonstrates a\nspintronic element whose transport characteristics are governed by an AFM. It\ndemonstrates that sensitivity to low magnetic fields can be combined with\nlarge, spin-orbit coupling induced magneto-transport anisotropy using a single\nmagnetic electrode. The AFM-TAMR provides means to study magnetic\ncharacteristics of AFM films by an electronic transport measurement."
    },
    {
        "anchor": "General atomistic approach for modeling metal-semiconductor interfaces\n  using density functional theory and non-equilibrium Green's function: Metal-semiconductor contacts are a pillar of modern semiconductor technology.\nHistorically, their microscopic understanding has been hampered by the\ninability of traditional analytical and numerical methods to fully capture the\ncomplex physics governing their operating principles. Here we introduce an\natomistic approach based on density functional theory and non-equilibrium\nGreen's function, which includes all the relevant ingredients required to model\nrealistic metal-semiconductor interfaces and allows for a direct comparison\nbetween theory and experiments via I-V bias curves simulations. We apply this\nmethod to characterize an Ag/Si interface relevant for photovoltaic\napplications and study the rectifying-to-Ohmic transition as function of the\nsemiconductor doping.We also demonstrate that the standard \"Activation Energy\"\nmethod for the analysis of I-V bias data might be inaccurate for non-ideal\ninterfaces as it neglects electron tunneling, and that finite-size atomistic\nmodels have problems in describing these interfaces in the presence of doping,\ndue to a poor representation of space-charge effects. Conversely, the present\nmethod deals effectively with both issues, thus representing a valid\nalternative to conventional procedures for the accurate characterization of\nmetal-semiconductor interfaces.",
        "positive": "Challenges for density functional theory in simulating metal-metal\n  singlet bonding: a case study of dimerized VO2: VO2 is renowned for its electric transition from an insulating monoclinic\n(M1) phase characterized by V-V dimerized structures, to a metallic rutile (R)\nphase above 340 Kelvin. This transition is accompanied by a magnetic change:\nthe M1 phase exhibits a non-magnetic spin-singlet state, while the R phase\nexhibits a state with local magnetic moments. Simultaneous simulation of the\nstructural, electric, and magnetic properties of this compound is of\nfundamental importance, but the M1 phase alone has posed a significant\nchallenge to density functional theory (DFT). In this study, we show none of\nthe commonly used DFT functionals, including those combined with on-site\nHubbard U to better treat 3d electrons, can accurately predict the V-V dimer\nlength. The spin-restricted method tends to overestimate the strength of the\nV-V bonds, resulting in a small V-V bond length. Conversely, the\nspin-symmetry-breaking method exhibits the opposite trends. Each\nbond-calculation method underscores one of the two contentious mechanisms,\ni.e., Peierls or Mott, involved in the metal-insulator transition in VO2. To\nelucidate the challenges encountered in DFT, we also employ an effective\nHamiltonian that integrates one-dimensional magnetic sites, thereby revealing\nthe inherent difficulties linked with the DFT computations."
    },
    {
        "anchor": "Unconventional anomalous Hall effect from magnetization parallel to the\n  electric field: In the anomalous Hall effect (AHE), the magnetization, electric field and the\nHall current are presumed to be mutually vertical to each other. In this work,\nwe propose an unconventional AHE where the magnetization, the electric field\nand Hall current stay inside the same plane. Such an AHE is odd under\ntime-reversal and exists even when the magnetization is parallel to the\nelectric field or Hall current, different from the planar Hall effect which is\neven under time-reversal. Here, we term it parallel anomalous Hall effect\n(PAHE). We reveal that the PAHE exists when all the point group rotational and\nreflection symmetries are broken where the Berry curvature field is not\nnecessarily parallel to the magnetization axis. We further demonstrate the PAHE\nin a ferrimagnetic Weyl semimetal FeCr$_2$Te$_4$.",
        "positive": "Reducing the Aspect Ratio of Contact Holes by In-Situ Low-Angle Cross\n  Sectioning: Auger analysis of high-aspect ratio contact holes of integrated\nmicroelectronic devices is a challenging analytical task. Due to geometrical\nshadowing the primary electron beam and the energy analyser have not the\nrequired direct line of sight to the analysis area simultaneously. To solve\nthis problem sample preparation is needed to flatten the 3-dimensional\ngeometry. Here the new approach of in-situ low-angle cross sectioning is\napplied. By this method material gets removed inside the Auger instrument while\nthe sample is sputtered by Ar+ ions at nearly grazing incidence utilizing the\nedge of a mask, which partly covers the sample. A very shallow bevel with\nrespect to the sample surface is produced. Thus along the bevel contact holes\nwith suitable aspect ratios are available for the Auger analysis."
    },
    {
        "anchor": "Ternary Bismuthide SrPtBi2: Computation and Experiment in Synergism to\n  Explore Solid-State Materials: A combination of theoretical calculation and the experimental synthesis to\nexplore the new ternary compound is demonstrated in the Sr-Pt-Bi system. Since\nPt-Bi is considered as a new critical charge-transfer pair for\nsuperconductivity, it inspired us to investigate the Sr-Pt-Bi system. With a\nthorough calculation of all the known stable/metastable compounds in the\nSr-Pt-Bi system and crystal structure predictions, the thermodynamic stability\nof hypothetical stoichiometry, SrPtBi2, is determined. Followed by the\nhigh-temperature synthesis and crystallographic analysis, the first ternary\nbismuthide in Sr-Pt-Bi, SrPtBi2 was prepared and the stoichiometry was\nconfirmed experimentally. SrPtBi2 crystallizes in the space group Pnma (S.G.\n62, Pearson Symbol oP48), which matches well with theoretical prediction using\nan adaptive genetic algorithm (AGA). Using first-principles calculations, we\ndemonstrate that the orthorhombic structure has lower formation energies than\nother 112 structure types, such as tetragonal BaMnBi2 (CuSmP2) and LaAuBi2\n(CuHfSi2) structure types. The bonding analysis indicates the Pt-Bi\ninteractions play a critical role in structural stability. The physical\nproperties measurements show the metallic properties with low electron-phonon\ninteractions at the low temperature, which agrees with the electronic structure\nassessment.",
        "positive": "Quantum-confinement and Structural Anisotropy result in\n  Electrically-Tunable Dirac Cone in Few-layer Black Phosphorous: 2D materials are well-known to exhibit interesting phenomena due to quantum\nconfinement. Here, we show that quantum confinement, together with structural\nanisotropy, result in an electric-field-tunable Dirac cone in 2D black\nphosphorus. Using density functional theory calculations, we find that an\nelectric field, E_ext, applied normal to a 2D black phosphorus thin film, can\nreduce the direct band gap of few-layer black phosphorus, resulting in an\ninsulator-to-metal transition at a critical field, E_c. Increasing E_ext beyond\nE_c can induce a Dirac cone in the system, provided the black phosphorus film\nis sufficiently thin. The electric field strength can tune the position of the\nDirac cone and the Dirac-Fermi velocities, the latter being similar in\nmagnitude to that in graphene. We show that the Dirac cone arises from an\nanisotropic interaction term between the frontier orbitals that are spatially\nseparated due to the applied field, on different halves of the 2D slab. When\nthis interaction term becomes vanishingly small for thicker films, the Dirac\ncone can no longer be induced. Spin-orbit coupling can gap out the Dirac cone\nat certain electric fields; however, a further increase in field strength\nreduces the spin-orbit-induced gap, eventually resulting in a\ntopological-insulator-to-Dirac-semi-metal transition."
    },
    {
        "anchor": "Enhanced photogalvanic current in topological insulators via Fermi\n  energy tuning: We achieve the enhancement of circular photogalvanic effect arising from the\nphoto-injection of spins in topological insulator thin films by tuning the\nFermi level ($E_{\\rm F}$). A series of (Bi$_{1-x}$Sb$_x$)$_2$Te$_3$ thin films\nwere tailored so that the Fermi energy ranges above 0.34 eV to below 0.29 eV of\nthe Dirac point, i.e., from the bulk conduction band bottom to the valence band\ntop through the bulk in-gap surface-Dirac cone. The circular photogalvanic\ncurrent, indicating a flow of spin-polarized surface-Dirac electrons, shows a\npronounced peak when the $E_{\\rm F}$ is set near the Dirac point and is also\ncorrelated with the carrier mobility. Our observation reveals that there are\nsubstantial scatterings between the surface-Dirac and bulkstate electrons in\nthe generation process of spin-polarized photocurrent, which can be avoided by\ndesigning the electronic structure in topological insulators.",
        "positive": "CLEASE: A versatile and user-friendly implementation of Cluster\n  Expansion method: Materials exhibiting a substitutional disorder such as multicomponent alloys\nand mixed metal oxides/oxyfluorides are of great importance in many scientific\nand technological sectors. Disordered materials constitute an overwhelmingly\nlarge configurational space, which makes it practically impossible to be\nexplored manually using first-principles calculations such as density\nfunctional theory (DFT) due to the high computational costs. Consequently, the\nuse of methods such as cluster expansion (CE) is vital in enhancing our\nunderstanding of the disordered materials. CE dramatically reduces the\ncomputational cost by mapping the first-principles calculation results on to a\nHamiltonian which is much faster to evaluate. In this work, we present our\nimplementation of the CE method, which is integrated as a part of the Atomic\nSimulation Environment (ASE) open-source package. The versatile and\nuser-friendly code automates the complex set up and construction procedure of\nCE while giving the users the flexibility to tweak the settings and to import\ntheir own structures and previous calculation results. Recent advancements such\nas regularization techniques from machine learning are implemented in the\ndeveloped code. The code allows the users to construct CE on any bulk lattice\nstructure, which makes it useful for a wide range of applications involving\ncomplex materials. We demonstrate the capabilities of our implementation by\nanalyzing the two example materials with varying complexities: a binary metal\nalloy and a disordered lithium chromium oxyfluoride."
    },
    {
        "anchor": "Determination of Intrinsic Ferroelectric Polarization in Orthorhombic\n  Manganites with E-type Spin Order: By directly measuring electrical hysteresis loops using the Positive-Up\nNegative-Down (PUND) method, we accurately determined the remanent\nferroelectric polarization Pr of orthorhombic RMnO3 (R = Ho, Tm, Yb, and Lu)\ncompounds below their E-type spin ordering temperatures. We found that LuMnO3\nhas the largest Pr of 0.17 uC/cm^2 at 6 K in the series, indicating that its\nsingle-crystal form can produce a Pr of at least 0.6 \\muuC/cm^2 at 0 K.\nFurthermore, at a fixed temperature, Pr decreases systematically with\nincreasing rare earth ion radius from R = Lu to Ho, exhibiting a strong\ncorrelation with the variations in the in-plane Mn-O-Mn bond angle and Mn-O\ndistances. Our experimental results suggest that the contribution of the Mn t2g\norbitals dominates the ferroelectric polarization.",
        "positive": "Understanding adhesion at as-deposited interfaces from ab initio\n  thermodynamics of deposition growth: thin-film alumina on titanium carbide: We investigate the chemical composition and adhesion of chemical vapour\ndeposited thin-film alumina on TiC using and extending a recently proposed\nnonequilibrium method of ab initio thermodynamics of deposition growth (AIT-DG)\n[Rohrer J and Hyldgaard P 2010 Phys. Rev. B 82 045415]. A previous study of\nthis system [Rohrer J, Ruberto C and Hyldgaard P 2010 J. Phys.: Condens. Matter\n22 015004] found that use of equilibrium thermodynamics leads to predictions of\na non-binding TiC/alumina interface, despite the industrial use as a\nwear-resistant coating. This discrepancy between equilibrium theory and\nexperiment is resolved by the AIT-DG method which predicts interfaces with\nstrong adhesion. The AIT-DG method combines density functional theory\ncalculations, rate-equation modelling of the pressure evolution of the\ndeposition environment and thermochemical data. The AIT-DG method was\npreviously used to predict prevalent terminations of growing or as-deposited\nsurfaces of binary materials. Here we extent the method to predict surface and\ninterface compositions of growing or as-deposited thin films on a substrate and\nfind that inclusion of the nonequilibrium deposition environment has important\nimplications for the nature of buried interfaces."
    },
    {
        "anchor": "Spin flop and crystalline anisotropic magnetoresistance in CuMnAs: Recent research works have shown that the magnetic order in some\nantiferromagnetic materials can be manipulated and detected electrically, due\nto two physical mechanisms: Neel-order spin-orbit torques and anisotropic\nmagnetoresistance. While these observations open up opportunities to use\nantiferromagnets for magnetic memory devices, different physical\ncharacterization methods are required for a better understanding of those\nmechanisms. Here we report a magnetic field induced rotation of the\nantiferromagnetic Neel vector in epitaxial tetragonal CuMnAs thin films. Using\nsoft x-ray magnetic linear dichroism spectroscopy, x-ray photoemission electron\nmicroscopy, integral magnetometry and magneto-transport methods, we demonstrate\nspin-flop switching and continuous spin reorientation in antiferromagnetic\nfilms with uniaxial and biaxial magnetic anisotropies, respectively. From\nfield-dependent measurements of the magnetization and magnetoresistance, we\nobtain key material parameters including the anisotropic magnetoresistance\ncoefficients, magnetocrystalline anisotropy, spin-flop and exchange fields.",
        "positive": "Influence of electric field on the Eu+3 photolumiscence in lead-free\n  ferroelectric Na1/2Bi1/2TiO3: Eu modified Na1/2Bi1/2TiO3 (NBT) was investigated for electric-field induced\nEu+3 photoluminescence (PL) and structural changes. Detailed analysis revealed\nthat below a critical Eu composition electric field irreversibly suppresses the\nstructural heterogeneity inherent of the host matrix NBT and brings about a\nlong range ferroelectric state with rhombohedral (R3c) distortion. PL study\nrevealed that structural disorder on the nano-scale opens new channels of\nradiative transitions which can be suppressed by electric field. This study\nsuggests that Eu+3 luminescence can be used to probe the relative degree of\nfield induced structural ordering in relaxor ferroelectrics and also in high\nperformance piezoelectric alloys where electric field couples very strongly\nwith the lattice and structural degrees of freedom."
    },
    {
        "anchor": "Structural transformations in Cu, Ag, and Au metal nanoclusters: Finite-temperature structures of Cu, Ag, and Au metal nanoclusters are\ncalculated in the entire temperature range from 0 K to melting using a\ncomputational methodology that we proposed recently [Settem \\emph{et al.},\nNanoscale, 2022, 14, 939]. In this method, Harmonic Superposition Approximation\n(HSA) and Parallel Tempering Molecular Dynamics (PTMD) are combined in a\ncomplementary manner. HSA is accurate at low temperatures and fails at higher\ntemperatures. PTMD, on the other hand, effectively samples the high temperature\nregion and melting. This method is used to study the size- and system-dependent\ncompetition between various structural motifs of Cu, Ag, and Au nanoclusters in\nthe size range 1 to 2 nm. Results show that there are mainly three types of\nstructural changes in metal nanoclusters depending on whether a solid-solid\ntransformation occurs. In the first type, global minimum is the dominant motif\nin the entire temperature range. In contrast, when a solid-solid transformation\noccurs, the global minimum transforms either completely to a different motif or\npartially resulting in a co-existence of multiple motifs. Finally, nanocluster\nstructures are analyzed to highlight the system-specific differences across the\nthree metals.",
        "positive": "Modulation of conductance and superconductivity by top-gating in\n  LaAlO3/SrTiO3 2-dimensional electron systems: We report the electrical top-gating of a 2-dimensional electron gas (2DEG)\nformed at the LaAlO3/SrTiO3 interface, using electron-beam evaporated Au gate\nelectrodes. In these structures, epitaxial LaAlO3 films grown by pulsed laser\ndeposition induce the 2DEGs at the interface to the SrTiO3 substrate and\nsimultaneously act as the gate dielectric. The structured top-gates enable a\nlocal tuning and complete on/off switching of the interface\n(super)-conductivity, while maintaining the usual, intrinsic characteristics\nfor these LaAlO3/SrTiO3 interfaces when no gate voltage is applied."
    },
    {
        "anchor": "A feasibility analysis towards the simulation of hysteresis with\n  spin-lattice dynamics: We use spin-lattice dynamics simulations to study the possibility of modeling\nthe magnetic hysteresis behavior of a ferromagnetic material. The temporal\nevolution of the magnetic and mechanical degrees of freedom is obtained through\na set of two coupled Langevin equations. Hysteresis loops are calculated for\ndifferent angles between the external field and the magnetocrystalline\nanisotropy axes. The influence of several relevant parameters is studied,\nincluding the field frequency, magnetic damping, magnetic anisotropy (magnitude\nand type), magnetic exchange, and system size. The role played by a moving\nlattice is also discussed. For a perfect bulk ferromagnetic system we find\nthat, at low temperatures, the exchange and lattice dynamics barely affect the\nloops, while the field frequency and magnetic damping have a large effect on\nit. The influence of the anisotropy magnitude and symmetry are found to follow\nthe expected behavior. We show that a careful choice of simulation parameters\nallows for an excellent agreement between the spin-lattice dynamics\nmeasurements and the paradigmatic Stoner-Wohlfarth model. Furthermore, we\nextend this analysis to intermediate and high temperatures for the perfect bulk\nsystem and for spherical nanoparticles, with and without defects, reaching\nvalues close to the Curie temperature. In this temperature range, we find that\nlattice dynamics has a greater role on the magnetic behavior, especially in the\nevolution of the defective samples. The present study opens the possibility for\nmore accurate inclusion of lattice defects and thermal effects in hysteresis\nsimulations",
        "positive": "Structure and lattice excitations of the copper substituted lead\n  oxyapatite Pb$_{9.06(7)}$Cu$_{0.94(6)}$(PO$_{3.92(4)}$)$_{6}$O$_{0.96(3)}$: The copper substituted lead oxyapatite,\nPb$_{10-x}$Cu$_{x}$(PO$_{3.92(4)}$)$_{6}$O$_{0.96(3)}$ (x=0.94(6)) was studied\nusing neutron and x-ray diffraction and neutron spectroscopy techniques. The\ncrystal structure of the main phase of our sample, which has come to be\ncolloquially known as LK-99, is verified to possess a hexagonal structure with\nspace group $P 6_{3}/m$, alongside the presence of impurity phases Cu and\nCu$_2$S. We determine the primary substitution location of the Cu as the Pb1\n($6h$) site, with a small substitution at the Pb2 ($4f$) site. Consequently, no\nclear Cu-doping-induced structural distortion was observed in the investigated\ntemperature region between 10~K and 300~K. Specially, we did not observe a\nreduction of coordinate number at the Pb2 site or a clear tilting of PO$_4$\ntetrahedron. Magnetic characterization reveals a diamagnetic signal in the\nspecimen, accompanied by a very weak ferromagnetic component at 2 K. No\nlong-range magnetic order down to 10 K was detected by the neutron diffraction.\nInelastic neutron scattering measurements did not show magnetic excitations for\nenergies up to 350 meV. There is no sign of a superconducting resonance in the\nexcitation spectrum of this material. The measured phonon density of states\ncompares well with density functional theory calculations performed for the\nmain LK-99 phase and its impurity phases. Our study may shed some insight into\nthe role of the favored substitution site of copper in the absence of\nstructural distortion and superconductivity in LK-99."
    },
    {
        "anchor": "Visualizing Van der Waals Epitaxial Growth of Two-Dimensional\n  Heterostructures: Understanding the growth mechanisms of two-dimensional (2D) van der Waals\n(vdW) heterostructures is of great importance in exploring their\nfunctionalities and device applications. A custom-built system integrating\nphysical vapor deposition and optical microscopy/Raman spectroscopy was\nemployed to study the dynamic growth processes of 2D vdW heterostructures in\nsitu. This allows us to identify a new growth mode with a distinctly different\ngrowth rate and morphology from those of the conventional linear growth mode.\nWe propose a model that explains the difference in morphologies and quantifies\nthe growth rates of the two modes by taking the role of surface diffusion into\naccount. We have systematically investigated a range of material combinations\nincluding CdI2/WS2, CdI2/MoS2, CdI2/WSe2, PbI2/WS2, PbI2/MoS2, PbI2/WSe2 and\nBi2Se3/WS2. These findings may be generalized to the synthesis of many other 2D\nheterostructures with controlled morphologies and physical properties,\nbenefiting future device applications.",
        "positive": "Ab initio study of proper topological ferroelectricity in layered\n  perovskite La2Ti2O7: We present a first-principles investigation of ferroelectricity in layered\nperovskite oxide La2Ti2O7 (LTO), one of the compounds with highest Curie\ntemperature known (1770 K). Our calculations reveal that LTO's ferroelectric\ntransition results from the condensation of two soft modes that have the same\nsymmetry and are strongly coupled anharmonically. Further, the leading\ninstability mode essentially consists of rotations of the oxygen octahedra that\nare the basic building block of the perovskite structure; remarkably, because\nof the particular topology of the lattice, such O6 rotations give raise to a\nspontaneous polarization in LTO. The effects discussed thus constitute an\nexample of how nano-structuring -- provided here by the natural layering of LTO\n-- makes it possible to obtain a significant polar character in structural\ndistortions that are typically non-polar. We discuss the implications of our\nfindings as regards the design of novel multifunctional materials. Indeed, the\nobserved proper ferroelectricity driven by O6 rotations provides the ideal\nconditions to obtain strong magnetoelectric effects."
    },
    {
        "anchor": "Performance of a non-empirical meta-GGA density functional for\n  excitation energies: It is known that the adiabatic approximation in time-dependent density\nfunctional theory usually provides a good description of low-lying excitations\nof molecules. In the present work, the capability of the adiabatic nonempirical\nmeta-generalized gradient approximation (meta-GGA) of Tao, Perdew, Staroverov,\nand Scuseria (TPSS) to describe atomic and molecular excitations is tested. The\nadiabatic (one-parameter) hybrid version of the TPSS meta-GGA and the adiabatic\nGGA of Perdew, Burke, and Ernzerhof (PBE) are also included in the test. The\nresults are compared to experiments and to two well-established hybrid\nfunctionals PBE0 and B3LYP. Calculations show that both adiabatic TPSS and\nTPSSh functionals produce excitation energies in fairly good agreement with\nexperiments, and improve upon the adiabatic local spin density approximation\nand, in particular, the adiabatic PBE GGA. This further confirms that TPSS is\nindeed a reliable nonhybrid universal functional which can serve as the\nstarting point from which higher-level approximations can be constructed. The\nsystematic underestimate of the low-lying vertical excitation energies of\nmolecules with time-dependent density functionals within the adiabatic\napproximation suggests that further improvement can be made with nonadiabatic\ncorrections.",
        "positive": "Geometric magnonics with chiral magnetic domain walls: Spin wave, the collective excitation of magnetic order, is one of the\nfundamental angular momentum carriers in magnetic systems. Understanding the\nspin wave propagation in magnetic textures lies in the heart of developing pure\nmagnetic information processing schemes. Here we show that the spin wave\npropagation across a chiral domain wall follows simple geometric trajectories,\nsimilar to the geometric optics. And the geometric behaviors are qualitatively\ndifferent in normally magnetized film and tangentially magnetized film. We\nidentify the lateral shift, refraction, and total reflection of spin wave\nacross a ferromagnetic domain wall. Moreover, these geometric scattering\nphenomena become polarization-dependent in antiferromagnets, indicating the\nemergence of spin wave birefringence inside antiferromagnetic domain wall."
    },
    {
        "anchor": "Analytical Model for Light Modulating Impedance Spectroscopy (LIMIS) in\n  All-Solid-State p-n Junction Solar Cells at Open-Circuit: Non-circuit theory drift-diffusion numerical simulation of standard\npotentiostatic impedance spectroscopy (IS) is a well-known strategy for\ncharacterization of materials and electronic devices. It implies the\ntime-dependent solutions from the continuity and Poisson's equations under\nsmall perturbation of the bias boundary condition at the electrodes. But in the\ncase of photo-sensitive devices a small light perturbation can be also taken\nmodulating the generation rate along the absorber bulk. In that focus, this\nwork approaches a set of analytical solutions for the signals of IS and\nintensity modulated photocurrent and photovoltage spectroscopies, IMPS and IMVS\nrespectively, from one-sided p-n junction solar cells at open-circuit.\nSubsequently, a photo-impedance signal named light intensity modulated\nimpedance spectroscopy (LIMIS equals IMVS over IMPS) is analytically simulated\nand its difference with respect to IS suggests a correlation with the surface\ncharge carrier recombination velocity. This is an illustrative result and\nstarting point for future more realistic numerical simulations.",
        "positive": "A critical comparison of methods for the determination of the ageing\n  sensitivity in biomedical grade yttria stabilized zirconia: Since the recent failure events of two particular series of zirconia femoral\nheads for total hip replacement prosthesis, a large decrease in the use of\nzirconia ceramics for orthopaedic implants has been observed. In spite of the\nbiomedical success of this material during the last ten years, this was\nrequired for safety reasons, until the cause of the failures is known. It has\nbeen shown that these failures were related to the low temperature hydrothermal\ndegradation (also known as ageing). Thus it is crucial to better understand the\nageing behaviour, in order to be able to assess its importance and then control\nit if required. In this paper, various techniques relevant to assess the\nhydrothermal degradation sensitivity of biomedical grade yttria stabilized\nzirconia are discussed and compared. The expected outputs of conventional\nmethods, i.e. X-Ray diffraction and scanning electron microscopy are examined.\nMore recent methods like optical interferometry and atomic force microscopy are\npresented, with their respective benefits and drawbacks. An up to date\ncomparison of these different techniques is provided, and their use for\nensuring the long term reliability of a particular batch of zirconia in terms\nof ageing degradation is demonstrated."
    },
    {
        "anchor": "Graph-based machine learning beyond stable materials and relaxed crystal\n  structures: There has been a recent surge of interest in using machine learning to\napproximate density functional theory (DFT) in materials science. However, many\nof the most performant models are evaluated on large databases of computed\nproperties of, primarily, materials with precise atomic coordinates available,\nand which have been experimentally synthesized, i.e., which are\nthermodynamically stable or metastable. These aspects provide challenges when\napplying such models on theoretical candidate materials, for example for\nmaterials discovery, where the coordinates are not known. To extend the scope\nof this methodology, we investigate the performance of the Crystal Graph\nConvolutional Neural Network (CGCNN) on a data set of theoretical structures in\nthree related ternary phase diagrams (Ti,Zr,Hf)-Zn-N, which thus include many\nhighly unstable structures. We then investigate the impact on the performance\nof using atomic positions that are only partially relaxed into local energy\nminima. We also explore options for improving the performance in these\nscenarios by transfer learning, either from models trained on a large database\nof mostly stable systems, or a different but related phase diagram. Models\npre-trained on stable materials do not significantly improve performance, but\nmodels trained on similar data transfer very well. We demonstrate how our\nfindings can be utilized to generate phase diagrams with a major reduction in\ncomputational effort.",
        "positive": "Chiral criticality in doped Mn$_{1-y}$Fe$_y$Si compounds: The critical spin fluctuations in doped compounds Mn$_{1-y}$Fe$_y$Si have\nbeen studied by means of ac-susceptibility measurements, polarized neutron\nsmall angle scattering and spin echo spectroscopy. It is shown that these\ncompounds undergo the transition from the paramagnetic to helimagnetic phase\nthrough continuous, yet well distinguishable crossovers: (i) from paramagnetic\nto partially chiral, (ii) from partially chiral to highly chiral fluctuating\nstate. The crossover points are identified on the basis of combined analysis of\nthe temperature dependence of ac-susceptibility and polarized SANS data. The\nwhole transition is marked by two inflection point of the temperature\ndependence of ac-susceptibility: the upper one corresponds to the crossover to\npartially chiral state at $T^*$, where the inverse correlation length $\\kappa\n\\approx 2 k$, the lower one corresponds to the transition to the spin helix\nstructure. The intermediate crossover to the highly chiral phase is observed at\nthe inflection point $T_k$ of the first derivative of ac-susceptibility, where\n$\\kappa \\approx k$. The temperature crossovers to the highly chiral fluctuating\nstate is associated with the enhancing influence of the Dzyaloshinskii-Moria\ninteraction close to $T_c$."
    },
    {
        "anchor": "Tunable phase transitions in half-Heusler TbPtBi compound: We report various phase transitions in half-Heusler TbPtBi compound using\nDensity Functional Theory (DFT). Specifically, inclusion of spin-orbit coupling\n(SOC) leads to band inversion resulting in transition from the metallic to the\ntopological semimetallic phase. However, in presence of SOC, there is a phase\ntransition from the topological semimetal to the trivial semimetal when the\nmaterial is subjected to compressive strain ($\\lt -7\\%$). Subsequently, under\nfurther increase of compressive strain ($\\ge -7\\%$), we find an opening of a\ndirect band gap at the $\\Gamma$ point, driving the system from the trivial\nsemimetallic to the semiconducting state with changes in the sequence of bands.\nIn the absence of SOC, only transition from the metallic to the semiconducting\nphase is noticed. Under tensile strain, the TbPtBi compound maintains its phase\nas in the unstrained condition but with an increase in the hole pocket at the\nFermi level, both in the absence and presence of SOC. These tunable phase\ntransitions (especially as a fraction of strain) make this compound very\npromising for application in various quantum devices such as highly sensitive\nstrain gauges.",
        "positive": "Electrical Detection of Coherent Nuclear Spin Oscillations in\n  Phosphorus-Doped Silicon Using Pulsed ENDOR: We demonstrate the electrical detection of pulsed X-band Electron Nuclear\nDouble Resonance (ENDOR) in phosphorus-doped silicon at 5\\,K. A pulse sequence\nanalogous to Davies ENDOR in conventional electron spin resonance is used to\nmeasure the nuclear spin transition frequencies of the $^{31}$P nuclear spins,\nwhere the $^{31}$P electron spins are detected electrically via spin-dependent\ntransitions through Si/SiO$_2$ interface states, thus not relying on a\npolarization of the electron spin system. In addition, the electrical detection\nof coherent nuclear spin oscillations is shown, demonstrating the feasibility\nto electrically read out the spin states of possible nuclear spin qubits."
    },
    {
        "anchor": "Hidden Structural Order in Orthorhombic Tantalum Pentoxide (Ta$_2$O$_5$): We investigate using first-principles calculations the atomic structure of\nthe orthorhombic phase of Ta$_2$O$_5$. Although this structure has been studied\nfor decades, the correct structural model is controversial owing to the\ncomplication of structural disorder. We identify a new low-energy high-symmetry\nstructural model where all Ta and O atoms have correct formal oxidation states\nof +5 and -2, respectively, and the experimentally reported triangular lattice\nsymmetry of the Ta sublattice appears dynamically at finite temperatures. To\nunderstand the complex atomic structure of the Ta$_2$O$_3$ plane, a triangular\ngraph-paper representation is devised and used alongside oxidation state\nanalysis to reveal infinite variations of the low-energy structural model. The\nstructural disorder of Ta$_2$O$_5$ observed in experiments is attributed to the\nintrinsic structural variations, and oxygen vacancies that drive collective\nrelaxation of the O sublattice.",
        "positive": "Characterizing spin transport: detection of spin accumulation via\n  magnetic stray field: Spin transport in electric conductors is largely determined by two material\nparameters - spin diffusion length and spin Hall angle. In metals, these are\ntypically determined indirectly by probing magnetoresistance in magnet/metal\nheterostructures, assuming knowledge of the interfacial properties. We suggest\nprofiling the charge current induced spin Hall spin accumulation in metals, via\ndetection of the magnetic stray field generated by the associated static\nmagnetization, as a direct means of determining spin transport parameters. We\nevaluate the spatial profile of the stray field as well as the Oersted field\ngenerated by the charge current. We thus demonstrate that such a charge current\ninduced spin accumulation is well within the detection limit of contemporary\ntechnology. Measuring the stray fields may enable direct access to spin-related\nproperties of metals paving the way for a better and consistent understanding\nof spin transport therein."
    },
    {
        "anchor": "Stark Tuning of Donor Electron Spins in Silicon: We report Stark shift measurements for 121Sb donor electron spins in silicon\nusing pulsed electron spin resonance. Interdigitated metal gates on top of a\nSb-implanted 28Si epi-layer are used to apply electric fields. Two Stark\neffects are resolved: a decrease of the hyperfine coupling between electron and\nnuclear spins of the donor and a decrease in electron Zeeman g-factor. The\nhyperfine term prevails at X-band magnetic fields of 0.35T, while the g-factor\nterm is expected to dominate at higher magnetic fields. A significant linear\nStark effect is also resolved presumably arising from strain.",
        "positive": "Phase diagram of Sr$_{1-x}$Ba$_x$MnO$_3$ as a function of chemical\n  doping, epitaxial strain and external pressure: We use \\textit{ab initio} calculations to systematically study the phase\ndiagram of multiferroic Sr$_{1-x}$Ba$_x$MnO$_3$ ($0 \\leq x \\leq 1$) as a\nfunction of chemical doping, epitaxial strain and external pressure. We find\nthat by replacing Sr with Ba in cubic SrMnO$_3$ and imposing epitaxial strain,\nthe material can be tuned to the vicinity of a first order transition between\ntwo multiferroic phases, one antiferromagnetic with a smaller polarization and\none ferromagnetic with a larger polarization. A giant effective\nmagneto-electric coupling and cross-field control (electric field control of\nmagnetism or magnetic field control of polarization) can be achieved in the\nvicinity of the transition. The dependence of the theoretically computed\ntransition point on the choice of exchange correlation functionals is\ndetermined and is found to be non-negligible. We also show that the perovskite\nstructure of BaMnO$_3$ can be stabilized relative to its hexagonal polymorphs\nat pressures larger than 20 GPa."
    },
    {
        "anchor": "Shake-induced order in nanosphere systems: Self-assembled patterns obtained from a drying nanosphere suspension are\ninvestigated by computer simulations and simple experiments. Motivated by the\nearlier experimental results of Sasaki and Hane and Schope, we confirm that\nmore ordered triangular lattice structures can be obtained whenever a moderate\nintensity random shaking is applied on the drying system. Computer simulations\nare realized on an improved version of a recently elaborated\nBurridge-Knopoff-type model. Experiments are made following the setup of Sasaki\nand Hane, using ultrasonic radiation as source for controlled shaking.",
        "positive": "Accelerated design of linear-superelastic Ti-Nb nanocomposite alloys\n  with ultralow modulus via high-throughput phase-field simulations and machine\n  learning: The controlled design of martensitic transformation (MT) to achieve specific\nproperties is crucial for the innovative application of shape memory alloys\n(SMAs) in advanced technologies. Herein, we explore and design the MT behaviors\nand the mechanical properties of Ti-Nb nanocomposites by combining\nhigh-throughput phase-field simulations and machine learning (ML) approaches.\nBased on the systematic phase-field simulations, we obtain data sets of the\nmechanical properties for various nanocomposites constructed by four\nmacroscopic degrees of freedom, which can be employed to design and optimize\nthe microstructures for different applications. To accelerate the phase-field\nscreening of the desired metallic biomaterials, a ML assisted strategy is\nadopted to perform multi-objective optimization of the mechanical properties,\nthrough which promising nanocomposite configurations are pre-screened for the\nnext set of phase-field simulations. With the ML guided simulations, an\noptimized candidate composed of Nb-rich matrix and Nb-lean nanofillers that\nexhibits a combination of unprecedented mechanical properties, including\nultra-low modulus, linear super-elasticity, and near-hysteresis-free is\ndesigned. The exceptional mechanical properties in the nanocomposite originate\nfrom optimized continuous MT rather than a sharp first-order transition, which\nis common in typical SMAs. This work provides a new computational approach and\ndesign concept for developing novel functional materials with extraordinary\nproperties."
    },
    {
        "anchor": "Study of the electronic structure of short chain oligothiophenes: The electronic structure of short-chain thiophenes (thiophene,\n2,2'-bithiophene and 2,2':5',2'-terthiophene) in the gas phase has been\ninvestigated by combining the outcomes of Near-Edge X-ray-Absorption\nFine-Structure (NEXAFS) and X-ray Photoemission Spectroscopy (XPS) at the C\nK-edge with those of density functional theory (DFT) calculations. The\ncalculated NEXAFS spectra provide a comprehensive description of the main\nexperimental features and allow their attribution. The evolution of the C1s\nNEXAFS spectral features is analyzed as a function of the number of thiophene\nrings; a tendency to a stabilization for increasing chain length is found. The\ncomputation of the binding energy allows to assign the experimental XPS peaks\nto the different carbon sites on the basis of both the inductive effects\ngenerated by the presence of the S atom as well as of the differential\naromaticity effects.",
        "positive": "Lossless Multi-Scale Constitutive Elastic Relations with Artificial\n  Intelligence: The elastic properties of materials derive from their electronic and atomic\nnature. However, simulating bulk materials fully at these scales is not\nfeasible, so that typically homogenized continuum descriptions are used\ninstead. A seamless and lossless transition of the constitutive description of\nthe elastic response of materials between these two scales has been so far\nelusive. Here we show how this problem can be overcome by using Artificial\nIntelligence (AI). A Convolutional Neural Network (CNN) model is trained, by\ntaking the structure image of a nanoporous material as input and the\ncorresponding elasticity tensor, calculated from Molecular Statics (MS), as\noutput. Trained with the atomistic data, the CNN model captures the size- and\npore-dependency of the material's elastic properties which, on the physics\nside, can stem from surfaces and non-local effects. Such effects are often\nignored in upscaling from atomistic to classical continuum theory. To\ndemonstrate the accuracy and the efficiency of the trained CNN model, a Finite\nElement Method (FEM) based result of an elastically deformed nanoporous beam\nequipped with the CNN as constitutive law is compared with that by a full\natomistic simulation. The good agreement between the atomistic simulations and\nthe FEM-AI combination for a system with size and surface effects establishes a\nnew lossless scale bridging approach to such problems. The trained CNN model\ndeviates from the atomistic result by 9.6\\% for porosity scenarios of up to\n90\\% but it is about 230 times faster than the MS calculation and does not\nrequire to change simulation methods between different scales. The efficiency\nof the CNN evaluation together with the preservation of important atomistic\neffects makes the trained model an effective atomistically-informed\nconstitutive model for macroscopic simulations of nanoporous materials and\nsolving of inverse problems."
    },
    {
        "anchor": "Low-temperature thermal conductivity in polycrystalline graphene: The low-temperature thermal conductivity in polycrystalline graphene is\ntheoretically studied. The contributions from three branches of acoustic\nphonons are calculated by taking into account scattering on sample borders,\npoint defects and grain boundaries. Phonon scattering due to sample borders and\ngrain boundaries is shown to result in a $T^{\\alpha}$-behaviour in the thermal\nconductivity where $\\alpha$ varies between 1 and 2. This behaviour is found to\nbe more pronounced for nanosized grain boundaries.\n  PACS: 65.80.Ck, 81.05.ue, 73.43.Cd",
        "positive": "Influence of Solution Parameters on Phase Formation and Morphology of\n  Electrospun Poly(vinylidene fluoride) Nanofiber: Poly(vinylidene fluoride), PVDF nanofibers were prepared using\nelectrospinning method and the influence of electrospinning parameters such as\nPVDF concentration, DMF:Acetone ratio on the formation of different phases\n({\\alpha}, \\b{eta}, and {\\gamma}) and desired morphology were investigated. A\ndetail analysis of X-ray diffraction (XRD) and Fourier-transform infrared\n(FTIR) spectrometer data by deconvoluting the peaks were carried out for\nassigning and accurately identifying the peaks associated to a particular PVDF\nphase. SEM micrographs further helped in understanding the mechanism of desired\n\\b{eta}-phase as well as in obtaining a condition for bead-free nanofibers.\nInterestingly, the mechanism of formation of phases are found mostly governed\nby the balance between surface tension and viscosity which is controlled by\nPVDF concentration and acetone content in the solution. A PVDF concentration of\n20% (w/v) and DMF:Acetone ratio 1:1 was found suitable for maximum\n\\b{eta}-phase in a completely bead-free nanofibers. The methodology and\nunderstanding of underlying mechanism of desired phase and morphology suggest a\nguideline for optimization of \\b{eta}-phase and bead-free fibers in PVDF-based\nnanocomposite as well."
    },
    {
        "anchor": "Multi hole bands and quasi 2-dimensionality in Cr2Ge2Te6 studied by\n  angle-resolved photoemission spectroscopy: In the present work, we investigate the electronic structure of the\ntwo-dimensional (2D) ferromagnet Cr2Ge2Te6 by photoemission spectroscopy and ab\ninitio calculations. Our results demonstrate the presence of multiple hole-type\nbands in the vicinity of the Fermi level indicating that the material can\nsupport high electrical conductivity by manipulating the chemical potential.\nAlso, our photon energy dependent angle resolved photoemission experiment\nrevealed that several of the hole bands exhibit weak dispersion with varied\nincident photon energy providing experimental signature for its two\ndimensionality. These findings can pave the way for further studies towards the\napplication of Cr2Ge2Te6 in electronic devices.",
        "positive": "New apparatus for DTA at 2000 bar: thermodynamic studies on Au, Ag, Al\n  and HTSC oxides: A new DTA (Differential Thermal Analysis) device was designed and installed\nin a Hot Isostatic Pressure (HIP) furnace in order to perform high-pressure\nthermodynamic investigations up to 2 kbar and 1200C. Thermal analysis can be\ncarried out in inert or oxidising atmosphere up to p(O2) = 400 bar. The\ncalibration of the DTA apparatus under pressure was successfully performed\nusing the melting temperature (Tm) of pure metals (Au, Ag and Al) as standard\ncalibration references. The thermal properties of these metals have been\nstudied under pressure. The values of DV (volume variation between liquid and\nsolid at Tm), ROsm (density of the solid at Tm) and ALPHAm (linear thermal\nexpansion coefficient at Tm) have been extracted. A very good agreement was\nfound with the existing literature and new data were added. This HP-DTA\napparatus is very useful for studying the thermodynamics of those systems where\none or more volatile elements are present, such as high TC superconducting\noxides. DTA measurements have been performed on Bi,Pb(2223) tapes up to 2 kbar\nunder reduced oxygen partial pressure (p(O2) = 0.07 bar). The reaction leading\nto the formation of the 2223 phase was found to occur at higher temperatures\nwhen applying pressure: the reaction DTA peak shifted by 49C at 2 kbar compared\nto the reaction at 1 bar. This temperature shift is due to the higher stability\nof the Pb-rich precursor phases under pressure, as the high isostatic pressure\nprevents Pb from evaporating."
    },
    {
        "anchor": "Anodic Decomposition of Surface Films on High Voltage Spinel Surfaces --\n  Density Function Theory and Experimental Study: Oxidative decomposition of organic-solvent-based liquid electrolytes at\ncathode material interfaces has been identified as a main reason for rapid\ncapacity fade in high-voltage lithium ion batteries. The evolution of \"cathode\nelectrolyte interphase: (CEI) films, partly or completely consisting of\nelectrolyte decomposition products, has also recently been demonstrated to be\ncorrelated with battery cycling behavior at high potentials. Using Density\nFunctional Theory (DFT) calculations, the hybrid PBE0 functional, and the (001)\nsurfaces of spinel oxides as models, we examine these two interrelated\nprocesses. Consistent with previous calculations, ethylene carbonate (EC)\nsolvent molecules are predicted to be readily oxidized on the Li(x)Mn(2)O(4)\n(001) surface at modest operational voltages, forming adsorbed organic\nfragments. Further oxidative decompostion of such CEI fragments to release CO2\ngas is however predicted to require higher voltages consistent with\nLi(x)Ni(0.5)Mn(1.5)O(4) (LNMO) at smaller x values. We argue that multi-step\nreactions, involving first formation of CEI films and then further oxidization\nof CEI at higher potentials, are most relevant to capacity fade. Mechanisms\nassociated with dissolution or oxidation of native Li2CO3 films, which is\nremoved before the electrolyte is in contact with oxide surfaces, are also\nexplored.",
        "positive": "In-situ force microscopy to investigate fracture in stretchable\n  electronics: insights on local surface mechanics and conductivity: Stretchable conductors are of crucial relevance for emerging technologies\nsuch as wearable electronics, low-invasive bioelectronic implants or soft\nactuators for robotics. A critical issue for their development regards the\nunderstanding of defect formation and fracture of conducting pathways during\nstress-strain cycles. Here we present a novel atomic force microscopy (AFM)\nmethod that provides multichannel images of surface morphology, conductivity,\nand elastic modulus during sample deformation. To develop the method, we\ninvestigate in detail the mechanical interactions between the AFM tip and a\nstretched, free-standing thin film sample. Our findings reveal the conditions\nto avoid artifacts related to sample bending modes or resonant excitations. As\nan example, we analyze strain effects in thin gold films deposited on a soft\nsilicone substrate. Our technique allows to observe the details of microcrack\nopening during tensile strain and their impact on local current transport and\nsurface mechanics. We find that although the film fractures into separate\nfragments, at higher strain a current transport is sustained by a tunneling\nmechanism. The microscopic observation of local defect formation and their\ncorrelation to local conductivity will provide novel insight to design more\nrobust and fatigue resistant stretchable conductors."
    },
    {
        "anchor": "Neural network based order parameter for phase transitions and its\n  applications in high-entropy alloys: Phase transition is one of the most important phenomena in nature and plays a\ncentral role in materials design. All phase transitions are characterized by\nsuitable order parameters, including the order-disorder phase transition.\nHowever, finding a representative order parameter for complex systems is\nnontrivial, such as for high-entropy alloys. Given variational autoencoder's\n(VAE) strength of reducing high dimensional data into few principal components,\nhere we coin a new concept of \"VAE order parameter\". We propose that the\nManhattan distance in the VAE latent space can serve as a generic order\nparameter for order-disorder phase transitions. The physical properties of the\norder parameter are quantitatively interpreted and demonstrated by multiple\nrefractory high-entropy alloys. Assisted by it, a generally applicable alloy\ndesign concept is proposed by mimicking the nature mixing of elements. Our\nphysically interpretable \"VAE order parameter\" lays the foundation for the\nunderstanding of and alloy design by chemical ordering.",
        "positive": "Application of van der Waals Density Functional to an Extended System:\n  Adsorption of Benzene and Naphthalene on Graphite: It is shown that it is now possible to include van der Waals interactions via\na nonempirical implementation of density functional theory to describe the\ncorrelation energy in electronic structure calculations on infinite systems of\nno particular symmetry. The vdW-DF functional [Phys. Rev. Lett. 92, 246401\n(2004)] is applied to the adsorption of benzene and naphthalene on an infinite\nsheet of graphite, as well as the binding between two graphite sheets.\nComparison with recent thermal desorption data [Phys. Rev. B 69, 535406 (2004)]\nshows great promise for the vdW-DF method."
    },
    {
        "anchor": "On the Thermomechanical Properties and Fracture Patterns of the Novel\n  Nonbenzenoid Carbon Allotrope (Biphenylene Network): A Reactive Molecular\n  Dynamics Study: Recently, a new two-dimensional carbon allotrope, named biphenylene network\n(BPN) was experimentally realized. The BPN structure is composed of four-,\nsix-, and eight-membered rings of sp$^2$-hybridized carbon atoms. In this work,\nwe carried out fully-atomistic reactive (ReaxFF) molecular dynamics simulations\nto study the thermomechanical properties and fracture patterns of non-defective\nand defective (nanocracks) BPN. Our results show that under uniaxial tensile\nloading, BPN is converted into four distinct morphologies before fracture\nstarts. This conversion process is dependent on the stretching direction. Some\nof the formed structures are mainly formed by eight-membered rings, which have\ndifferent shapes in each morphology. In one of them, a graphitization process\nwas observed before the complete fracture. Importantly, in the presence of\nnanocracks, no new morphologies are formed. BPN exhibits a distinct fracture\nprocess when contrasted to graphene. After the critical strain threshold, the\ngraphene transitions from an elastic to a brittle regime, while BPN can exhibit\ndifferent inelastic stages. These stages are associated with the appearance of\nnew morphologies. However, BPN shares some of the exceptional graphene\nproperties. Its calculated Young's modulus and melting point values are\ncomparable to the graphene ones, about 1019.4 GPa and 4024K, respectively.",
        "positive": "Detection of hidden structures on all scales in amorphous materials and\n  complex physical systems: basic notions and applications to networks, lattice\n  systems, and glasses: Recent decades have seen the discovery of numerous complex materials. At the\nroot of the complexity underlying many of these materials lies a large number\nof possible contending atomic- and larger-scale configurations and the\nintricate correlations between their constituents. For a detailed\nunderstanding, there is a need for tools that enable the detection of pertinent\nstructures on all spatial and temporal scales. Towards this end, we suggest a\nnew method by invoking ideas from network analysis and information theory. Our\nmethod efficiently identifies basic unit cells and topological defects in\nsystems with low disorder and may analyze general amorphous structures to\nidentify candidate natural structures where a clear definition of order is\nlacking. This general unbiased detection of physical structure does not require\na guess as to which of the system properties should be deemed as important and\nmay constitute a natural point of departure for further analysis. The method\napplies to both static and dynamic systems."
    },
    {
        "anchor": "Ab initio multiplet plus cumulant approach for correlation effects in\n  x-ray photoelectron spectroscopy: The treatment of electronic correlations in open-shell systems is among the\nmost challenging problems of condensed matter theory. Current approximations\nare only partly successful. Ligand field multiplet theory (LFMT) has been\nwidely successful in describing intra-atomic correlation effects in x-ray\nspectra, but typically ignores itinerant states. The cumulant expansion for the\none electron Greens function has been successful in describing shake-up effects\nbut ignores atomic multiplets. More complete methods, such as dynamic\nmean-field theory can be computationally problematic. Here we show that\nseparating the dynamic Coulomb interactions into local and longer-range parts\nwith ab initio parameters yields a combined multiplet plus cumulant approach\nthat accounts for both local atomic multiplets and satellite excitations. The\napproach is illustrated in transition metal oxides and explains the multiplet\npeaks, charge-transfer satellites and distributed background features observed\nin XPS experiment.",
        "positive": "Layer-by-layer growth and growth-mode transition of SrRuO3 thin films on\n  atomically flat single-terminated SrTiO3 (111) surfaces: We report on growth-mode transitions in the growth of SrRuO3 thin films on\natomically flat Ti4+ single-terminated SrTiO3 (111) substrates, investigated by\nreflection high-energy electron diffraction and atomic force microscopy. Over\nthe first ~9 unit cells, the dominant growth mode changes from island to\nlayer-by-layer for the growth rate of 0.074 unit cells/sec and the growth\ntemperature of 700 C. Moreover, in the course of growing SrRuO3 films, the\ngoverning growth mode of interest can be manipulated by changing the growth\ntemperature and the growth rate, which change allows for the selection of the\ndesired layer-by-layer mode. The present study thus paves the way for\nintegrations of SrRuO3 thin layers into (111)-orientated oxide\nheterostructures, and hence multi-functional devices, requiring control of the\nsharp atomic-level interfaces and the layer-by-layer growth mode."
    },
    {
        "anchor": "Misfit Strain Induced Giant Magnetoelectric Coupling in Thin Ferroic\n  Films: We show that misfit strain originated from the film-substrate lattice\nmismatch strongly increases the value of the quadratic magnetoelectric\ncoupling. The giant magnetoelectric coupling, size effects and misfit strain\ncause strong changes of ferroic films phase diagrams at zero external magnetic\nand electric fields, in particular, the transformation of antiferromagnetic\nphase into ferromagnetic or ferrimagnetic ones for compressive or tensile\nmisfit strains correspondingly as well as thickness induced paramagnetic or/and\nparaelectric phases appearance. Ferromagnetism appearance and magnetoelectric\ncoupling increase in thin ferroelectric-antiferromagnetic films is in agreement\nwith available experimental data and opens the way for tailoring of ferroic\nfilms magnetic and electric properties.",
        "positive": "Diffusion of small two-dimensional Cu Islands on Cu(111): Diffusion of small two dimensional Cu islands (containing up to 10 atoms) on\nCu(111) has been studied using the newly developed self-learning Kinetic Monte\nCarlo SLKMC method. It is based on a database of diffusion processes and their\nenergetics accumulated automatically during the implementation of the SLKMC\ncode. Results obtained from simulations in which atoms hop from one fcc hollow\nsite to another are compared with those obtained from a parallel set of\nsimulations in which the database is supplemented by processes revealed in\ncomplementary molecular dynamics simulations at 500 K. They include processes\ninvolving the hcp (stacking-fault) sites, which facilitate concerted motion of\nthe islands. A significant difference in the scaling of the effective diffusion\nbarriers with island size is observed between the two cases. In particular, the\npresence of concerted island motion leads to an almost linear increase in the\neffective diffusion barrier with size, while its absence accounts for strong\nsize-dependent oscillations and anomalous behavior for trimers and heptamers\nwhile the diffusion coefficients (calculated at 300 K, 500 K, and 700 K) do not\ndisplay any characteristic scaling with size. We also identify and discuss in\ndetail the key microscopic processes responsible for the diffusion and examine\nthe frequencies of their occurrence, as a function of island size and substrate\ntemperature."
    },
    {
        "anchor": "Current driven asymmetric magnetization switching in perpendicularly\n  magnetized CoFeB/MgO heterostructures: The flow of in-plane current through ultrathin magnetic heterostructures can\ncause magnetization switching or domain wall nucleation owing to bulk and\ninterfacial effects. Within the magnetic layer, the current can create magnetic\ninstabilities via spin transfer torques (STT). At interface(s), spin current\ngenerated from the spin Hall effect in a neighboring layer can exert torques,\nreferred to as the spin Hall torques, on the magnetic moments. Here, we study\ncurrent induced magnetization switching in perpendicularly magnetized CoFeB/MgO\nheterostructures with a heavy metal (HM) underlayer. Depending on the thickness\nof the HM underlayer, we find distinct differences in the inplane field\ndependence of the threshold switching current. The STT is likely responsible\nfor the magnetization reversal for the thinner underlayer films whereas the\nspin Hall torques cause the switching for thicker underlayer films. For the\nlatter, we find differences in the switching current for positive and negative\ncurrents and initial magnetization directions. We find that the growth process\nduring the film deposition introduces an anisotropy that breaks the symmetry of\nthe system and causes the asymmetric switching. The presence of such symmetry\nbreaking anisotropy enables deterministic magnetization switching at zero\nexternal fields.",
        "positive": "Domain nucleation across the metal-insulator transition of self-strained\n  V2O3 films: Bulk V2O3 features concomitant metal-insulator (MIT) and structural (SPT)\nphase transitions at TC ~ 160 K. In thin films, where the substrate clamping\ncan impose geometrical restrictions on the SPT, the epitaxial relation between\nthe V2O3 film and substrate can have a profound effect on the MIT. Here we\npresent a detailed characterization of domain nucleation and growth across the\nMIT in (001)-oriented V2O3 films grown on sapphire. By combining scanning\nelectron transmission microscopy (STEM) and photoelectron emission microscopy\n(PEEM), we imaged the MIT with planar and vertical resolution. We observed that\nupon cooling, insulating domains nucleate at the top of the film, where strain\nis lowest, and expand downwards and laterally. This growth is arrested at a\ncritical thickness of 50 nm from the substrate interface, leaving a persistent\nbottom metallic layer. As a result, the MIT cannot take place in the interior\nof films below this critical thickness. However, PEEM measurements revealed\nthat insulating domains can still form on a very thin superficial layer at the\ntop interface. Our results demonstrate the intricate spatial complexity of the\nMIT in clamped V2O3, especially the strain-induced large variations along the\nc-axis. Engineering the thickness-dependent MIT can provide an unconventional\nway to build out-of-plane geometry devices by using the persistent bottom metal\nlayer as a native electrode."
    },
    {
        "anchor": "Relaxation Between Bright Optical Wannier Excitons in Perovskite Solar\n  Absorber CH$_3$NH$_3$PbI$_3$: We study the light-absorbing states of the mixed-halide perovskite\nCH$_{3}$NH$_{3}$PbI$_2$Cl and tri-iodide perovskite CH$_{3}$NH$_{3}$PbI$_3$\nwith density functional and many-body calculations to explain the desirable\nphotovolatic features of these materials. The short-lived electron-hole bound\nstates produced in this photovoltaic material are of halide to lead electron\ntransfer character, with a Wannier-type exciton. Bethe-Salpeter (GW+BSE)\ncalculations of the absorption cross section reveal strong screening of the\nelectron-hole interaction. The atomic character of the exciton retains\nligand-to-metal character within the visible spectrum, with differing degrees\nof localization outside the unit cell. The average electron-hole separation in\nthe lowest exciton is found to be about 5$A^{\\circ}$, slightly larger than the\nPb-I bond length. Finally, we determine the role of methylammonium's dipole in\nthe ultrafast relaxation by preparing an atomistic model of the picosecond\nelectronic dynamics in the tri-iodide, PbI$_3$. Our model allows us to identify\nphonon modes which couple strongly to the electronic excitations, and explain\nthe picosecond timescale intra-band relaxation dynamics seen in recent\ntransient absorption experiments. We largely substantiate the conjectured three\nband model for the dynamics, but also identify other possible relaxation\nchannels in the tri-iodide.",
        "positive": "Anisotropic and extreme magnetoresistance in the magnetic semimetal\n  candidate Erbium monobismuthide: Rare-earth monopnictides display rich physical behaviors, featuring most\nnotably spin and orbital orders in their ground state. Here, we grow ErBi\nsingle crystal and study its magnetic, thermal and electrical properties. An\nanalysis of the magnetic entropy and magnetization indicates that the weak\nmagnetic anisotropy in ErBi possibly derives from the mixing effect, namely the\nanisotropic ground state of Er3+ (4f11) mingles with the isotropic excited\nstate through exchange interaction. At low temperature, an extremely large\nmagnetoresistance (~104%) with a parabolic magnetic-field dependence is\nobserved, which can be ascribed to the nearly perfect electron-hole\ncompensation and ultrahigh carrier mobility. When the magnetic field is rotated\nin the ab (ac) plane and the current flows in the b axis, the angular\nmagnetoresistance in ErBi shows a twofold (fourfold) symmetry. Similar case has\nbeen observed in LaBi where the anisotropic Fermi surface dominates the\nlow-temperature transport. Our theoretical calculation suggests that near the\nFermi level ErBi shares similarity with LaBi in the electronic band structures.\nThese findings indicate that the angular magnetoresistance of ErBi could be\nmainly determined by its anisotropic Fermi surface topology. Besides,\ncontributions from several other possibilities, including the spin-dependent\nscattering, spin-orbit scattering, and demagnetization correlation to the\nangular magnetoresistance of ErBi are also discussed."
    },
    {
        "anchor": "Dislocation-mediated plasticity in the Al$_{2}$Cu \u03b8-phase: The deformation behaviour of the intermetallic Al$_{2}$Cu-phase was\ninvestigated using atomistic simulations and micropillar compression, where\nslip on the unexpected {211} and {022} slip planes was revealed. Additionally,\nall possible slip systems for the intermetallic phases were further evaluated\nand a preference for the activation of slip systems based on their effective\ninterplanar distances as well as the effective Burgers vector is proposed. The\neffective interplanar distance corresponds to the manually determined\ninterplanar distance, whereas the effective Burgers vector takes a potential\ndislocation dissociation into account. This new order is: {211}1/2<111>,\n{022}1/2<111> and {022}<100>, {110}<001>, {310}<001>, {022}<011>,\n{110}1/2<111>, {112}<110> and {112}1/2<111> from high to low ratio of\ndeff/beff. Also, data on the critical resolved shear stresses of several of\nthese slip systems were measured.",
        "positive": "High-resolution 3D phase-contrast imaging beyond the depth of field\n  limit via ptychographic multi-slice electron tomography: Resolving single atoms in large-scale volumes has been a goal for atomic\nresolution microscopy for a long time. Electron microscopy has come close to\nthis goal using a combination of advanced electron optics and computational\nimaging algorithms. However, atomic-resolution 3D imaging in volumes larger\nthan the depth of field limit of the electron optics has so far been out of\nreach. Electron ptychography, a computational imaging method allowing to solve\nthe multiple-scattering problem from position- and momentum-resolved\nmeasurements, provides the opportunity to surpass this limit. Here, we\nexperimentally demonstrate atomic resolution three-dimensional phase-contrast\nimaging in a volume surpassing the depth of field limits using multi-slice\nptychographic electron tomography. We reconstruct tilt-series 4D-STEM\nmeasurements of a Co3O4 nanocube, yielding 1.75 {\\AA} resolution in a\nreconstructed volume of (18.2nm)^3."
    },
    {
        "anchor": "New frontiers in characterising ZrB$_2$-MoSi$_2$ ultra-high temperature\n  ceramics: The structure-property(S-P) correlation,especially in the context of\nhigh-temperature oxidation, in ZrB$_2$-MoSi$_2$ based Ultra High-Temperature\nCeramic Matrix Composites (UHTCMCs) have been extensively investigated for\nquite some time since the last 25 years and a countless amount of published\ndata is presently available in this field.On the other hand,emergence of\ncorrelative microscopy [1] has completely revolutionised the world of materials\nresearch, in a number of ways.However,owing to the challenges of sample\npreparation, there has hardly been a literature aimed at understanding the\naforesaid phenomenon of understanding S-P correlation,based on oxidation in\nZrB$_2$-MoSi$_2$ UHTCMCs,which,in future, may open up new frontiers of research\nin UHTCMCs.The present review intends to discuss some of the most interesting\ndata published existing in this field and intends to provide a brief overview\nof the challenges associated along with some of the currently unexplored\navenues in this field,especially in terms of fundamental research.However,in\nview of the enormous amount of research already done in understanding\noxidation-based S-P correlation in these materials,the author does not claim to\naddress all the issues which may be associated with understanding the same.",
        "positive": "Giant spin torque efficiency in naturally oxidized polycrystalline TaAs\n  thin films: We report the measurement of efficient charge-to-spin conversion at room\ntemperature in Weyl semimetal/ferromagnet heterostructures with both oxidized\nand pristine interfaces. Polycrystalline films of the Weyl semimetal, TaAs, are\ngrown by molecular beam epitaxy on (001) GaAs and interfaced with a metallic\nferromagnet (Ni$_{0.8}$Fe$_{0.2}$). Spin torque ferromagnetic resonance\n(ST-FMR) measurements in samples with an oxidized interface yield a spin torque\nefficiency as large as $\\xi_{\\mathrm{FMR}}=0.45\\pm 0.25$ for a 8 nm\nNi$_{0.8}$Fe$_{0.2}$ layer thickness. By studying ST-FMR in these samples with\nvarying Ni$_{0.8}$Fe$_{0.2}$ layer thickness, we extract a damping-like torque\nefficiency as high as $\\xi_{\\mathrm{DL}}=1.36\\pm 0.66$. In samples with a\npristine (unoxidized) interface, the spin torque efficiency has opposite sign\nto that observed in oxidized samples ($\\xi_{\\mathrm{FMR}}=-0.27\\pm 0.14$ for a\n5 nm Ni$_{0.8}$Fe$_{0.2}$ layer thickness). We also find a lower bound on the\nspin Hall conductivity ($424 \\pm 110 \\frac{\\hbar}{e}$ S/cm) which is\nsurprisingly consistent with theoretical predictions for the single crystal\nWeyl semimetal state of TaAs."
    },
    {
        "anchor": "Strengthening the magnetic interactions in pseudobinary first-row\n  transition metal thiocyanates, $\\it{M}$(NCS)$_{2}$: Understanding the effect of chemical composition on the strength of magnetic\ninteractions is key to the design of magnets with stronger exchange\ninteractions. The magnetic divalent first-row transition metal (TM)\nthiocyanates are a class of chemically simple layered molecular frameworks.\nHere, we report two new members of the family, manganese (II) thiocyanate,\nMn(NCS)$_{2}$, and iron (II) thiocyanate, Fe(NCS)$_{2}$. Using magnetic\nsusceptibility measurements on these materials and on cobalt (II) thiocyanate\nand nickel (II) thiocyanate, Co(NCS)$_{2}$ and Ni(NCS)$_{2}$, respectively, we\nidentify significantly stronger net antiferromagnetic interactions between the\nearlier TM ions-a decrease in the Weiss constant, \\theta, from 29 K for\nNi(NCS)$_{2}$ to -115 K for Mn(NCS)$_{2}$-a consequence of more diffuse 3d\norbitals, increased orbital overlap and increasing numbers of unpaired\n$\\it{t}$$_{2g}$ electrons. We elucidate the magnetic structures of these\nmaterials: Mn(NCS)$_{2}$, Fe(NCS)$_{2}$ and Co(NCS)$_{2}$ order into the same\nantiferromagnetic commensurate ground state, whilst Ni(NCS)$_{2}$ adopts a\nground state structure consisting of ferromagnetically ordered layers stacked\nantiferromagnetically. We show that magnetic molecular frameworks with\nsignificantly stronger net exchange interactions can be constructed by using\nearlier TMs.",
        "positive": "Magnetic-field -induced structural changes in the electron doped\n  manganites: CaxSm1-xMnO3 (x = 0.8, 0.85): We studied the correlation between magnetic, electrical, structural, and\nmagnetostriction properties of the electron doped manganites\nCa$_x$Sm$_{1-x}$MnO$_3$ (x = 0.85, 0.8). The paramagnetic to antiferromagnetic\ntransition in both the compounds while cooling is accompanied by an abrupt\nincrease of the spontaneous volume thermal expansion ($\\Delta $V/V = 0.07 % for\nx = 0.85 and 0.25 % for x = 0.2). The x = 0.15 exhibits multiple phase\nseparation at 5 K: G-type, and C-type antiferromagnetic phases in orthorhombic\n(\\QTR{it}{Pnma}) and monoclinic (\\QTR{it}{P2}$_1$\\QTR{it}{/m}) structures\nrespectively. Magnetic study on x = 0.85 also suggest ferromagnetic regions\npossibly in $Pnma$ structure coexist with the antiferromagnetic phases. The\nmagnetization (M = 1.2 $\\mu_B$) of x = 0.85 does not reach the value expected\nfor the complete alignment of Mn spins even at 12 T and at 12 K. Metamagnetic\ntransitions (C-type to Ferromagnetic) in both compounds are accompanied by\ncontraction of volumes under high magnetic fields. We suggest that a high\nmagnetic field induces \\QTR{it}{P2}$_1$\\QTR{it}{/m} (high volume) to\n\\QTR{it}{Pnma} (low volume) structural transition. This is also supported by\nthe neutron diffraction study."
    },
    {
        "anchor": "Scaling of Hybrid QDs-Graphene Photodetectors to Subwavelength Dimension: Emerging colloidal quantum dot (cQD) photodetectors currently challenge\nestablished state-of-the-art infrared photodetectors in response speed,\nspectral tunability, simplicity of solution processable fabrication, and\nintegration onto curved or flexible substrates. Hybrid phototransistors based\non 2D materials and cQDs, in particular, are promising due to their inherent\nphotogain enabling direct photosignal enhancement. The photogain is sensitive\nto both, measurement conditions and photodetector geometry. This makes the\ncross-comparison of devices reported in the literature rather involved. Here,\nthe effect of device length L and width W scaling to subwavelength dimensions\n(sizes down to 500 nm) on the photoresponse of graphene-PbS cQD\nphototransistors was experimentally investigated. Photogain and responsivity\nwere found to scale with 1/LW, whereas the photocurrent and specific\ndetectivity were independent of geometrical parameters. The measurements were\nperformed at scaled bias voltage conditions for comparable currents. Contact\neffects were found to limit the photoresponse for devices with L < 3 {\\mu}m.\nThe relation of gate voltage, bias current, light intensity, and frequency on\nthe photoresponse was investigated in detail, and a photogating efficiency to\nassess the cQD-graphene interface is presented. In particular, the specific\ndetectivity values in the range between 10^8 to 10^9 Jones (wavelength of 1550\nnm, frequency 6 Hz, room temperature) were found to be limited by the charge\ntransfer across the photoactive interface.",
        "positive": "Direct creation of micro-domains with positive and negative surface\n  potential on hydroxyapatite coatings: A method for the direct patterning of electrostatic potential at the surface\nof hydroxyapatite is presented here. Micro-domains of surface potential have\nbeen created on hydroxyapatite coatings by a 20 keV focused electron beam with\nminimal alterations of surface chemistry. The success of such approach has been\nconfirmed by Kelvin Probe Force Microscopy measurements, which show that this\nmethod is capable of creating micron sized positive and negative local\nelectrostatic potential. The shape and potential difference of these domains\nwere found to depend on the dose of total injected charge from the electron\nbeam as well as the speed with which such charge is injected."
    },
    {
        "anchor": "Combining the $\u0394$-Self-Consistent-Field and GW Methods for\n  Predicting Core Electron Binding Energies in Periodic Solids: For the computational prediction of core electron binding energies in solids,\ntwo distinct kinds of modelling strategies have been pursued: the\n$\\Delta$-Self-Consistent-Field method based on density functional theory (DFT),\nand the GW method. In this study, we examine the formal relationship between\nthese two approaches, and establish a link between them. The link arises from\nthe equivalence, in DFT, between the total energy difference result for the\nfirst ionization energy, and the eigenvalue of the highest occupied state, in\nthe limit of infinite supercell size. This link allows us to introduce a new\nformalism, which highlights how in DFT - even if the total energy difference\nmethod is used to calculate core electron binding energies - the accuracy of\nthe results still implicitly depends on the accuracy of the eigenvalue at the\nvalence band maximum in insulators, or at the Fermi level in metals. We\nexamine, whether incorporating a quasiparticle correction for this eigenvalue\nfrom GW theory improves the accuracy of the calculated core electron binding\nenergies, and find that the inclusion of vertex corrections is required for\nachieving quantitative agreement with experiment.",
        "positive": "Intrinsic magnetism of open boron nitride nanotubes: This paper has been withdrawn by the author due to the incomplete results."
    },
    {
        "anchor": "Tunable Quantum Spin Hall Effect via Strain in two-Dimensional Arsenene\n  Monolayer: The search for new quantum spin Hall (QSH) phase and effective manipulations\nof their edge states are very important for both fundamental sciences and\npractical applications. Here, we use first-principles calculations to study the\nstrain-driven topological phase transition of two-dimensional (2D) arsenene\nmonolayer. We find that the band gap of arsenene decreases with increasing\nstrain and changes from indirect to direct, and then the s-p band inversion\ntakes place at {\\Gamma} point as the tensile strain is larger than 11.14%,\nwhich lead to a nontrivially topological state. A single pair of topologically\nprotected helical edge states is established for the edge of arsenene, and\ntheir QSH states are confirmed with nontrivial topological invariant Z2 = 1. We\nalso propose high-dielectric BN as an ideal substrate for the experimental\nsynthesis of arsenene, maintaining its nontrivial topology. These findings\nprovide a promising candidate platform for topological phenomena and new\nquantum devices operating at nanoelectronics.",
        "positive": "Ab initio surface chemistry with chemical accuracy: First-principles calculations are a cornerstone of modern surface science and\nheterogeneous catalysis. However, accurate reaction energies and barrier\nheights are frequently inaccessible due to the approximations demanded by the\nlarge number of atoms. Here we combine developments in local correlation and\nperiodic correlated wavefunction theory to solve the many-electron\nSchr\\\"odinger equation for molecules on surfaces with chemical accuracy,\ncommonly defined as 1~kcal/mol. As a demonstration, we study water on the\nsurface of \\ce{Al2O3} and \\ce{TiO2}, two prototypical and industrially\nimportant metal oxides for which we obtain converged energies at the level of\ncoupled-cluster theory with single, double, and perturbative triple excitations\n[CCSD(T)], commonly known as the \"gold-standard\" in molecular quantum\nchemistry. We definitively resolve the energetics associated with water\nadsorption and dissociation, enabling us to address recent experiments and to\nanalyze the errors of more commonly used approximate theories."
    },
    {
        "anchor": "Cold dwell behaviour of Ti$_6$Al alloy: Understanding load shedding\n  using digital image correlation and crystal plasticity simulations: Digital image correlation (DIC) and crystal plasticity simulation were\nutilised to study cold dwell behaviour in a coarse grain Ti-6Al alloy at 3\ndifferent temperatures up to 230 C. Strains extracted from large volume grains\nwere measured during creep by DIC and were used to calibrate the crystal\nplasticity model. The values of critical resolved shear stresses (CRSS) of the\ntwo main slip systems (basal and prismatic) were determined as a function of\ntemperature. Stress along paths across the boundaries of two grain pairs, (1) a\n`rogue' grain pair and (2) a `non-rogue' grain pair, were determined at\ndifferent temperatures. Load shedding was observed in the `rogue' grain pair,\nwhere a stress increment during the creep period was found in the `hard' grain.\nAt elevated temperatures, 120 C was found to be the worst-case scenario as the\nstress difference at the grain boundaries of these two grain pairs were found\nto be the largest among the three temperatures. This can be attributed to the\nfact that the strain rate sensitivity of both prismatic and basal slip systems\nis at its greatest in this worst-case scenario temperature.",
        "positive": "Strain-tunable charge carrier mobility of atomically thin phosphorus\n  allotropes: We explore the impact of strain on charge carrier mobility of monolayer\n$\\alpha$, $\\beta$, $\\gamma$ and $\\delta$-P, the four well known atomically thin\nallotropes of phosphorus, using density functional theory. Owing to the highly\nanisotropic band dispersion, the charge carrier mobility of the pristine\nallotropes is significantly higher (more than 5 times in some cases) in one of\nthe principal directions (zigzag or armchair) as compared to the other.\nUniaxial strain (upto 6% compressive/tensile) leads to bandgap alteration in\neach of the allotropes, especially a direct to indirect bandgap semiconductor\ntransition in $\\gamma$-P and a complete closure of the bandgap in $\\gamma$ and\n$\\delta$-P. We find that the charge carrier mobility is enhanced typically by a\nfactor of $\\approx 5-10$ in all the allotropes due to uniaxial strain; notably\namong them a $\\approx 250$ (30) times increase of the hole (electron) mobility\nalong the armchair (zigzag) direction is observed in $\\beta$-P ($\\gamma$-P)\nunder a compressive strain, acting in the armchair direction. Interestingly,\nthe preferred electronic conduction direction can also be changed in case of\n$\\alpha$ and $\\gamma$-P, by applying strain."
    },
    {
        "anchor": "Giant anisotropy of Gilbert damping in epitaxial CoFe films: Tailoring Gilbert damping of metallic ferromagnetic thin films is one of the\ncentral interests in spintronics applications. Here we report a giant Gilbert\ndamping anisotropy in epitaxial Co$_{50}$Fe$_{50}$ thin film with a\nmaximum-minimum damping ratio of 400 \\%, determined by broadband spin-torque as\nwell as inductive ferromagnetic resonance. We conclude that the origin of this\ndamping anisotropy is the variation of the spin orbit coupling for different\nmagnetization orientations in the cubic lattice, which is further corroborate\nfrom the magnitude of the anisotropic magnetoresistance in Co$_{50}$Fe$_{50}$.",
        "positive": "Origin of the colossal positive and negative thermal expansion in\n  Ag$_3$[Co(CN)$_6$]: an {\\it ab initio} Density Functional Theory study: DFT calculations have been used to provide insights into the origin of the\ncolossal positive and negative thermal expansion in Ag$_3$[Co(CN)$_6]$. The\nresults confirm that the positive expansion within the trigonal basal plane and\nthe negative expansion in the orthogonal direction are coupled due to the\nexistence of a network defined by nearly-rigid bonds within the chains of\nCo--C--N--Ag--N--C--Co linkages. The origin of the colossal values of the\ncoefficients of thermal expansion arise from an extremely shallow energy\nsurface that allows a flexing of the structure with small energy cost. The\nthermal expansion can be achieved with a modest value of the overall\nGr\\\"{u}neisen parameter. The energy surface is so shallow that we need to\nincorporate a small empirical dispersive interaction to give ground-state\nlattice parameters that match experimental values at low temperature. We\ncompare the results with DFT calculations on two isostructural systems:\nH$_3$[Co(CN)$_6$], which is known to have much smaller values of the\ncoefficients of thermal expansion, and Au$_3$[Co(CN)$_6$], which has not yet\nbeen synthesised but which is predicted by our calculations to be another\ncandidate material for showing colossal positive and negative thermal\nexpansion."
    },
    {
        "anchor": "The variable properties of solid solutions A 1-x B x XO 4 : Tunable\n  photoluminescence in the case of Sr 1-x Pb x WO 4 series: Over the ten past years, various experimental studies of solid solutions A\n1-x B x XO 4 (e.g. A = Sr, B = Pb, X = W) with scheelite structures have\nevidenced correlations between structural, vibrational modifications due to\nchemical substitution, and increasing photoluminescence intensities under UV or\nX-ray excitation. We propose a simple semi-empirical approach based on local\nzones with different compositions, allowing simulating the variations of\nstructural, vibrational and photoluminescence characteristics, in the full\ncomposition range 0$\\le$x$\\le$1. The structural characteristics are cell\nparameters, cell distortions or crystallite size effect, Debye-Waller factors,\nRaman shifts characterizing vibrations and photoluminescence signals under UV\nor X-ray excitations. Each property is assumed to be represented by a\nnon-linear function Y(x) depending on composition x and on local\nmicrostructural disorder. To illustrate this approach based on the coexistence\nof local zones with different compositions, we have fitted the Y(x) function to\nexperimental data, which allowed us determining the significant parameters\ncharacteristic of the series with A=Sr, B=Pb and X = W. These parameters\ndeliver a new microstructural interpretation of the increasing\nphotoluminescence intensities observed for intermediate composition x in solid\nsolutions. A generalization of this approach to other series of solid solutions\nis quite possible.",
        "positive": "Heavy Fermion metal Fe16N2 and its giant magnetic moment: A new model is proposed for the strong ferromagnetism associated with\npartially localized orbitals in the Fe16N2 metallic system which draws\nsubstantially from models of heavy fermion metals. The basic idea is that the\nspatially isolated Fe-N clusters generate non-uniform charge density and\nincrease the d-d electron interaction significantly, leading to a highly spin\npolarized configuration for low lying 3d orbitals. Simulation based on LDA+U\nmethod is performed to illustrate the correlation between enhanced U and giant\nmagnetic moment."
    },
    {
        "anchor": "Charge ordering in oxides : a conundrum solved by resonant diffraction: We show that in mixed-valence 3d transition metal oxides undergoing a\nstructural transition, the low temperature phase results from an effective\nordering of the charge. This arrangement and the quantitative evaluation of the\natomic charges are determined by using resonant x-ray scattering experiments\nfurther analyzed with the help of ab initio calculations of the corresponding\nscattering factors. We have found that this reorganization concerns only a\nsmall fraction of electron and is necessary to reconcile all the experimental\ndata.",
        "positive": "Pressure Induced Thermodynamically Stable and Mechanically Robust\n  Li-rich Unknown Li-Sn Compounds: A Step Towards Improvement of Li-Sn\n  Batteries: Volume expansion and elastic softening of Sn anode on lithiation result in\nmechanical degradation and pulverization of Sn, affecting the overall\nperformance of Li-Sn batteries. It can however be overcome by using exotic high\npressure quenched phase as prelithiated reagent. Moreover, it is known that\nunder pressure many unusual stoichiometric which are basically impossible at\nambient pressure, can be synthesized, that may even survive the decompression\nfrom high to ambient pressure.We therefore have performed a comprehensive study\nusing evolutionary algorithm and density functional theory based simulations to\nunderstand the lithiation of Sn anode at pressure ranging from 1 atm to 20 GPa.\nThe ground state structures of all stable and metastable Li-Sn compounds have\nbeen identified at ambient and moderate pressures and their properties have\nbeen studied to understand the role of pressure in re-defining the reaction\nmechanism during charging-discharging process in Li-ion batteries. Besides the\nwell-known existing Li-Sn compounds, our studies reveal the existence of five\nunreported stoichiometries (Li8Sn3, Li3Sn1, Li4Sn1, Li5Sn1, and Li7Sn1) and\ntheir associated crystal structures at ambient and high pressure. While Li8Sn3\nhas been identified as one of the most stable Li-Sn compound in the entire\npressure range (1 atm-20 GPa), the pressure induced Li-rich compounds like\nLi5Sn1 and Li7Sn1 have been classified as providing higher theoretical\ngravimetric capacity of 1129 and 1580 mAh/g), respectively, than the capacity\nof the known most lithiated phase, i.e., Li17Sn4 (960 mAh/g).Most importantly,\nour calculations show reduction in volume expansion by ~ 50% at 20 GPa, and\nreveal that the application of pressure can reduce the chance of Li plating and\nimprove the mechanical properties, which are desired to make the battery safer\nand its life longer."
    },
    {
        "anchor": "Computational Discovery of Microstructured Composites with Optimal\n  Stiffness-Toughness Trade-Offs: The conflict between stiffness and toughness is a fundamental problem in\nengineering materials design. However, the systematic discovery of\nmicrostructured composites with optimal stiffness-toughness trade-offs has\nnever been demonstrated, hindered by the discrepancies between simulation and\nreality and the lack of data-efficient exploration of the entire Pareto front.\nWe introduce a generalizable pipeline that integrates physical experiments,\nnumerical simulations, and artificial neural networks to address both\nchallenges. Without any prescribed expert knowledge of material design, our\napproach implements a nested-loop proposal-validation workflow to bridge the\nsimulation-to-reality gap and discover microstructured composites that are\nstiff and tough with high sample efficiency. Further analysis of Pareto-optimal\ndesigns allows us to automatically identify existing toughness enhancement\nmechanisms, which were previously discovered through trial-and-error or\nbiomimicry. On a broader scale, our method provides a blueprint for\ncomputational design in various research areas beyond solid mechanics, such as\npolymer chemistry, fluid dynamics, meteorology, and robotics.",
        "positive": "Nonlinear optical properties of TeO$_2$ crystalline phases from first\n  principles: We have computed second and third nonlinear optical susceptibilities of two\ncrystalline bulk tellurium oxide polymorphs: $\\alpha$-TeO$_{2}$ (the most\nstable crystalline bulk phase) and $\\gamma$-TeO$_{2}$ (the crystalline phase\nthat ressembles the more to the glass phase. Third order nonlinear\nsusceptibilities of the crystalline phases are two orders of magnitude larger\nthan $\\alpha$-SiO$_{2}$ cristoballite, thus extending the experimental\nobservations on glasses to the case of crystalline compounds. While the\nelectronic lone pairs of Te contribute to those large values, a full\nexplanation of the anisotropy of the third order susceptibility tensor requires\na detailed analysis of the structure, in particular the presence of helical\nchains, that seems to be linked to cooperative non-local polarizabilty effects.\nOur results demonstrate that first-principles simulations are a powerful\npredictive tool to estimate nonlinear optical susceptibilitites of materials."
    },
    {
        "anchor": "Effects of strain, electric, and magnetic fields on lateral electron\n  spin transport in semiconductor epilayers: We construct a spin-drift-diffusion model to describe spin-polarized electron\ntransport in zincblende semiconductors in the presence of magnetic fields,\nelectric fields, and off-diagonal strain. We present predictions of the model\nfor geometries that correspond to optical spin injection from the absorption of\ncircularly polarized light, and for geometries that correspond to electrical\nspin injection from ferromagnetic contacts. Starting with the Keldysh Green's\nfunction description for a system driven out of equilibrium, we construct a\nsemiclassical kinetic theory of electron spin transport in strained\nsemiconductors in the presence of electric and magnetic fields. From this\nkinetic theory we derive spin-drift-diffusion equations for the components of\nthe spin density matrix for the specific case of spatially uniform fields and\nuniform electron density. We solve the spin-drift-diffusion equations\nnumerically and compare the resulting images with scanning Kerr microscopy data\nof spin-polarized conduction electrons flowing laterally in bulk epilayers of\nn-type GaAs. The spin-drift-diffusion model accurately describes the\nexperimental observations. We contrast the properties of electron spin\nprecession resulting from magnetic and strain fields. Spin-strain coupling\ndepends linearly on electron wave vector and spin-magnetic field coupling is\nindependent of electron wave vector. As a result, spatial coherence of\nprecessing spin flows is better maintained with strain than with magnetic\nfields, and the spatial period of spin precession is independent of the applied\nelectrical bias in strained structures whereas it is strongly bias dependent\nfor the case of applied magnetic fields.",
        "positive": "Leveraging Domain Adaptation for Accurate Machine Learning Predictions\n  of New Halide Perovskites: We combine graph neural networks (GNN) with an inexpensive and reliable\nstructure generation approach based on the bond-valence method (BVM) to train\naccurate machine learning models for screening 222,960 halide perovskites using\nstatistical estimates of the DFT/PBE formation energy (Ef), and the PBE and HSE\nband gaps (Eg). The GNNs were fined tuned using domain adaptation (DA) from a\nsource model, which yields a factor of 1.8 times improvement in Ef and 1.2 -\n1.35 times improvement in HSE Eg compared to direct training (i.e., without\nDA). Using these two ML models, 48 compounds were identified out of 222,960\ncandidates as both stable and that have an HSE Eg that is relevant for\nphotovoltaic applications. For this subset, only 8 have been reported to date,\nindicating that 40 compounds remain unexplored to the best of our knowledge and\ntherefore offer opportunities for potential experimental examination."
    },
    {
        "anchor": "Measurements of Thermophysical Property of Thin Films by Light Pulse\n  Heating Thermoreflectance Methods: Thermoreflectance methods by picosecond pulse heating and by nanosecond pulse\nheating have been developed under the same geometrical configuration as the\nlaser flash method by the National Metrology Institute of JAPAN, AIST. Using\nthese light pulse heating methods, thermal diffusivity of each layer of\nmultilayered thin films and boundary thermal resistance between the layers can\nbe determined from the observed transient temperature curves based on the\nresponse function method. The measurement results of various thin films as\ntransparent conductive films used for flat panel displays, hard coating films\nand multilayered films of the next generation phase-change optical disk will be\npresented.",
        "positive": "Symmetry and structure of carbon-nitrogen complexes in gallium arsenide\n  from infrared spectroscopy and first-principles calculations: Molecular-like carbon-nitrogen complexes in GaAs are investigated both\nexperimentally and theoretically. Two characteristic high-frequency stretching\nmodes at \\num{1973} and \\SI{2060}{cm^{-1}}, detected by Fourier transform\ninfrared absorption (FTIR) spectroscopy, appear in carbon- and\nnitrogen-implanted and annealed layers. From isotopic substitution it is\ndeduced that the chemical composition of the underlying complexes is CN$_2$ and\nC$_2$N, respectively. Piezospectroscopic FTIR measurements reveal that both\ncenters have tetragonal symmetry. For density functional theory (DFT)\ncalculations linear entities are substituted for the As anion, with the axis\noriented along the \\hkl<100> direction, in accordance with the experimentally\nascertained symmetry. The DFT calculations support the stability of linear\nN-C-N and C-C-N complexes in the GaAs host crystal in the charge states ranging\nfrom $+3$ to $-3$. The valence bonds of the complexes are analyzed using\nmolecular-like orbitals from DFT. It turns out that internal bonds and bonds to\nthe lattice are essentially independent of the charge state. The calculated\nvibrational mode frequencies are close to the experimental values and reproduce\nprecisely the isotopic mass splitting from FTIR experiments. Finally, the\nformation energies show that under thermodynamic equilibrium CN$_2$ is more\nstable than C$_2$N."
    },
    {
        "anchor": "Effect of growth conditions on optical properties of CdSe/ZnSe single\n  quantum dots: In this work, we have investigated the optical properties of two samples of\nCdSe quantum dots by using submicro-photoluminescence spectroscopy. The effect\nof vicinal-surface GaAs substrates on their properties has been also assessed.\nThe thinner sample, grown on a substrate with vicinal surface, includes only\ndots with a diameter of less than 10 nm (type A islands). Islands of an average\ndiameter of about 16 nm (type B islands) that are related to a phase transition\nvia a Stranski-Krastanow growth process are also distributed in the thicker\nsample grown on an oriented substrate. We have studied the evolution of\nlineshapes of PL spectra for these two samples by improving spatial resolution\nthat was achieved using nanoapertures or mesa structures. It was found that the\nuse of a substrate with the vicinal surface leads to the suppression of\nexcitonic PL emitted from a wetting layer.",
        "positive": "Intrinsic defects, fluctuations of the local shape, and the\n  photo-oxidation of black phosphorus: Black phosphorus is a monoatomic semiconducting layered material that\ndegrades exothermically in the presence of light and ambient contaminants. Its\ndegradation dynamics remain largely unknown. Even before degradation,\nlocal-probe studies indicate non-negligible local curvature --through a\nnon-constant height distribution-- due to the unavoidable presence of intrinsic\ndefects. We establish that these intrinsic defects are photo-oxidation sites\nbecause they lower the chemisorption barrier of ideal black phosphorus (> 10 eV\nand out of visible-range light excitations) right into the visible and\nultra-violet range (1.6 to 6.8 eV), thus enabling photo-induced oxidation and\ndissociation of oxygen dimers. A full characterization of the material's shape\nand of its electronic properties at the early stages of the oxidation process\nis presented as well. This study thus provides fundamental insights into the\ndegradation dynamics of this novel layered material."
    },
    {
        "anchor": "Electronic transport properties through thiophenes on switchable domains: The electronic transport of electrons and holes through stacks of\n$\\alpha$,$\\ome ga$-dicyano-$\\beta$,$\\beta$'-dibutyl- quaterthiophene (DCNDBQT)\nas part of a nov el organic ferroic field-effect transistor (OFFET) is\ninvestigated. The novel ap plication of a ferroelectric instead of a dielectric\nsubstrate provides the poss ibility to switch bit-wise the ferroelectric\ndomains and to employ the polarizat ion of these domains as a gate field in an\norganic semiconductor. A device conta ining very thin DCNDBQT films of around\n20 nm thickness is intended to be suitab le for logical as well as optical\napplications. We investigate the device proper ties with the help of a\nphenomenological model called multilayer organic light-e mitting diodes\n(MOLED), which was extended to transverse fields. The results sho wed, that\nspace charge and image charge effects play a crucial role in these org anic\ndevices.",
        "positive": "Isolated modes and percolation in lattice dynamics of (Be,Zn)Se: A mixed II-VI semiconductor Zn[1-x]Be[x]Se possesses non-trivial vibration\nproperties, because its two constituent compounds, ZnSe and BeSe, show very\ndifferent degree of covalency and hence high elastic contrast. An anomalous\nBe-Se vibration line has been observed mostly at intermediate Be content in the\nRaman spectra of thin (Zn,Be)Se films. In order to explain microscopic origins\nand the detailed composition of these lines, a first-principles calculation of\nvibration frequencies in a mixed crystal has been done, with frozen-phonon\ntechnique and supercell setup within the density functional theory, by the\nSiesta method, which uses norm-conserving pseudopotentials and strictly\nlocalized numerical basis functions. The calculations confirmed an earlier\nassumption that the anomalous Be-Se line appears due to the formation of\ncontinuous chains of a more rigid Be-rich pseudo-continuous phase formed within\nthe more soft Zn-rich host region on crossing the Be-Se bond percolation\nthreshold (~0.19). Different local deformation in percolated and non-percolated\nregions affect interatomic elastic interactions and split corresponding\nvibration lines. Besides confirming the percolation model qualitatively, the\ncalculation provides details about vibration patterns in different phonon\nmodes."
    },
    {
        "anchor": "Achieving atomic resolution magnetic dichroism by controlling the phase\n  symmetry of an electron probe: The calculations presented here reveal that an electron probe carrying\norbital angular momentum is just a particular case of a wider class of electron\nbeams that can be used to measure electron magnetic circular dichroism (EMCD)\nwith atomic resolution. It is possible to obtain an EMCD signal with atomic\nresolution by simply breaking the symmetry of the electron probe phase\ndistribution using the aberration-corrected optics of an scanning transmission\nelectron microscope. The required phase distribution of the probe depends on\nthe magnetic symmetry and crystal structure of the sample. The calculations\nindicate that EMCD signals utilizing the phase of the electron probe are as\nstrong as those obtained by nanodiffraction methods.",
        "positive": "Kwinking as the plastic forming mechanism of B19' NiTi martensite: Irreversible plastic forming of B19$^\\prime$ martensite of the NiTi shape\nmemory alloy is discussed within the framework of continuum mechanics. It is\nsuggested that the main mechanism arises from coupling between martensite\nreorientation and coordinated $[100](001)_{\\rm M}$ dislocation slip. A\nheuristic model is proposed, showing that the ${(20\\bar{1})_{\\rm M}}$\ndeformation-twin bands, commonly observed in experiments, can be interpreted as\na combination of dislocation-mediated kink bands, appearing due to strong\nplastic anisotropy, and reversible twinning of martensite. We introduce a term\n'kwinking' for this combination of reversible twinning and irreversible plastic\nkinking. The model is subsequently formulated using the tools of nonlinear\nelasticity theory of martensite and crystal plasticity, introducing 'kwink\ninterfaces' as planar, kinematically compatible interfaces between two\ndifferently plastically slipped variants of martensite. It is shown that the\n${(20\\bar{1})_{\\rm M}}$ kwink bands may be understood as resultsing from energy\nminimization, and that their nucleation and growth and their pairing with\n$(100)_{\\rm M}$ twins into specific patterns enables low-energy plastic forming\nof NiTi martensite. We conclude that kwinking makes plastic deformation of\nB19$^\\prime$ martensite in polycrystalline NiTi possible despite only one slip\nsystem being available."
    },
    {
        "anchor": "Degenerate magnetic ground state and metastable state on trihexagonal\n  Co-sublattices in Co3Sn2(S,Se)2 single crystals: A trihexagonal lattice has been predicted to retain a degenerate magnetic\nstate which enriches physical properties. Especially, Co3Sn2S2, possessing\ntrihexagonal Co-sublattices, has been observed to own topological quantum\nproperties. Experimentally, Co3Sn2S2 has been reported to have hidden magnetic\nphases due to magnetic anomalies. To clarify the hidden magnetic phase, we\nfabricated high-quality single crystals of Co3Sn2S2-xSex (x = 0, 0.26, & 0.86).\nThe Se-substitution is intended to broaden the distance between Co atoms. For\neach Se-composition, magnetizations of single-crystalline Co3Sn2S2-xSex\nimplicate that the magnetic ground state consists of the out-of-plane\nferromagnetism and the in-plane antiferromagnetism: Being degenerate.\nMeanwhile, along out-of-plane, remanent magnetizations of Co3Sn2S2-xSex have a\nfirst-order phase transition, so Co3Sn2S2-xSex owns an excited magnetic state,\ndenoted as the metastable state. Consequently, we have provided semiclassical\nmagnetic structures of the degenerate ground state and the metastable state via\nboth magnetic symmetries and experimental constraints. Moreover, we have\ndiscovered mechanisms raising degeneracy and metastability.",
        "positive": "Tuning electronic and phononic states with hidden order in disordered\n  crystals: Disorder in crystals is rarely random, and instead involves local\ncorrelations whose presence and nature are hidden from conventional\ncrystallographic probes. This hidden order can sometimes be controlled, but its\nimportance for physical properties of materials is not well understood. Using\nsimple models for electronic and interatomic interactions, we show how crystals\nwith identical average structures but different types of hidden order can have\nvery different electronic and phononic band structures. Increasing the strength\nof local correlations within hidden-order states can open band gaps and tune\nmode (de)localisation -- both mechanisms allowing for fundamental changes in\nphysical properties without long-range symmetry breaking. Taken together, our\nresults demonstrate how control over hidden order offers a new mechanism for\ntuning material properties, orthogonal to the conventional principles of\n(ordered) structure/property relationships."
    },
    {
        "anchor": "Compositions in YBa2Cu3Oy for 3-D bond order superconductors: Self-doping in YBa2Cu3Oy starts to switch from a charge balancing of chain\nmetal reduction and plane oxidation to one of chain ligand oxidation (O-) and\nplane reduction on quenching from >600K. Amongst the responses are plane\nexpansions and types of unusually strong superconductivity such as elevated\ntemperature superconductivity (ETS), observed through laser pulsing (Tc=552K*)\nand upon shot quenching (Tc=200K*). We ascribe ETS to limited 3-D\nsuperconductivity due to a correlated system of bond ordering within\nchain-plane sandwiches and propose how to stabilize it. Accordingly, plane\nexpanding n-doping arises from self-doping charge equilibration with local\nchain Cu of two-fold O coordination (2). The dumbbell type bonds of both apical\nO- are a result of high-energy environment and comparable in their metric with\nelectron pairs on the plane. Following empirical Tc=%(2)x11 we suggest\nincreasing %(2) to cause the observed retrograde rise in Tc (photo-induced\nreflectivity edge) to a theoretical limit of Tc=1100K* at 100%(2). We propose\ncompositions and heat treatments based on charge-lattice commensurability.\nPaired charge concentrations on planes, determined by bond ordering based on\nmagic number counts, suggest several promising candidates such as\nc=0.22=2/3a0x3b0, c=0.17=2/3x4 or c=0.080=2/5x5. The latter could be achieved\nwith 32%(2) and display Tc=352K* not only in laser pulsed but in shot quenched\nmaterials.",
        "positive": "Bose glass and superfuid phases of cavity polaritons: We report the calculation of cavity exciton-polariton phase diagram which\ntakes into account the presence of realistic structural disorder. Polaritons\nare modelled as weakly interacting two-dimensional bosons. We show that with\nincreasing density polaritons first undergo a quasi-phase transition towards a\nBose glass: the condensate is localized in at least one minimum of the disorder\npotential, depending on the value of the chemical potential of the polariton\nsystem. A further increase of the density leads to a percolation process of the\npolariton fluid which gives rise to a Kosterlitz-Thouless phase transition\ntowards superfluidity. The spatial representation of the condensate\nwavefunction as well as the spectrum of elementary excitations are obtained\nfrom the solution of the Gross-Pitaevskii equation for all the phases."
    },
    {
        "anchor": "Giant transverse magnetoresistance in an asymmetric system of three\n  GaAs/AlGaAs quantum wells in a strong magnetic field at room temperature: The giant transverse magnetoresistance is observed in the case of\nphotoinduced nonequilibrium carriers in an asymmetric undoped system of three\nGaAs/AlGaAs quantum wells at room temperature. In a magnetic field of 75 kOe,\nthe resistance of nanostructure being studied increases by a factor of 1.85.\nThe magnetoresistance depends quadratically on the magnetic field in low fields\nand tends to saturation in high fields. This phenomenon is attributed to the\nrearrangement of the electron wave function in magnetic field. Using the fact\nthat the incoherent part of the scattering probability for electron scattering\non impurities and bulk defects is proportional to the integral of the forth\npower of the envelope wave function, the calculated field dependence of the\nmagnetoresistance is shown to be similar to that observed experimentally.",
        "positive": "Study of photoinduced valence dynamics in\n  EuNi$_2$(Si$_{0.21}$Ge$_{0.79}$)$_2$ through time-resolved X-ray absorption\n  spectroscopy: The photoinduced valence dynamics of EuNi$_2$(Si$_{0.21}$Ge$_{0.79}$)$_2$ are\ninvestigated using time-resolved X-ray absorption spectroscopy for Eu\n$M_5$-edge. Through the pump-probe technique with synchrotron X-ray and\nTi:sapphire laser pulse, a photoinduced valence transition is observed from\nEu$^{3+}$ to Eu$^{2+}$. Because the lifetime of a photoinduced state can be up\nto 3 ns, a metastable state is considered to be realized. By comparing the\nexperimental results with the theoretical calculations, the photoinduced\nvalence transition between Eu 4$f$ and conduction electrons is quantitatively\nevaluated."
    },
    {
        "anchor": "Hydrogen Storage by Polylithiated Molecules and Nanostructures: We study polylithiated molecules as building blocks for hydrogen storage\nmaterials, using first-principles calculations. $\\clifour$ and $\\olitwo$ bind\n12 and 10 hydrogen molecules, respectively, with an average binding energy of\n0.10 and 0.13 eV, leading to gravimetric densities of 37.8 and 40.3 weight % H.\nBonding between Li and C or O is strongly polar and $\\hyd$ molecules attach to\nthe partially charged Li atoms without dissociating, which is favorable for\n(de)hydrogenation kinetics. CLi$_n$ and OLi$_m$ molecules can be chemically\nbonded to graphene sheets to hinder the aggregation of such molecules. In\nparticular B or Be doped graphene strongly bind the molecules without seriously\naffecting the hydrogen binding energy. It still leads to a hydrogen storage\ncapacity in the range 5-8.5 wt % H.",
        "positive": "Spin Resolution and Evidence for Superexchange on NiO(001) observed by\n  Force Microscopy: The spin order of the nickel oxide (001) surface is resolved, employing\nnon-contact atomic force microscopy at 4.4 K using bulk Fe- and SmCo-tips\nmounted on a qPlus sensor that oscillates at sub-50 pm amplitudes. The\nspin-dependent signal is hardly detectable with Fe-tips. In contrast, SmCo-tips\nyield a height contrast of 1.35 pm for Ni ions with opposite spins. SmCo tips\neven show a small height contrast on the O atoms of 0.5 pm within the 2x1 spin\nunit cell, pointing to the observation of superexchange. We attribute this to\nthe increased magnetocrystalline anisotropy energy of SmCo, which stabilizes\nthe magnetic moment at the apex. Atomic force spectroscopy on the Ni up, Ni\ndown and O lattice site reveals a magnitude of the exchange energy of merely 1\nmeV at the closest accessible distance with an exponential decay length of\n\\lambda_exc = 18 pm."
    },
    {
        "anchor": "Tuning of the ultrafast demagnetization by ultrashort spin polarized\n  currents in multi-sublattice ferrimagnets: Femtosecond laser pulses can be used to induce ultrafast changes of the\nmagnetization in magnetic materials. Several microscopic mechanisms have been\nproposed to explain the observations, including the transport of ultrashort\nspin-polarized hot-electrons (SPHE). Such ultrafast spin currents find growing\ninterest because of the recent challenges in ultrafast spintronics however they\nare only poorly characterized. One of the key challenges is to characterize the\nspin-polarized ultrafast currents and the microscopic mechanisms behind SPHE\ninduced manipulation of the magnetization, especially in the case of\ntechnologically relevant ferrimagnetic alloys. Here, we have used a combined\napproach using time- and element-resolved X-ray magnetic circular dichroism and\ntheoretical calculations based on atomistic spin-dynamics simulations to\naddress the ultrafast transfer of the angular momentum from spin-polarized\ncurrents into ferrimagnetic Fe74Gd26 films and the concomitant reduction of\nsub-lattice magnetization. Our study shows that using a Co/Pt multilayer as a\npolarizer in a spin-valve structure, the SPHE drives the demagnetization of the\ntwo sub-lattices of the Fe74Gd26 film. This behaviour is explained based on two\nphysical mechanisms, i.e., spin transfer torque and thermal fluctuations\ninduced by the SPHE. We provide a quantitative description of the heat transfer\nof the ultrashort SPHE pulse to the Fe74Gd26 films, as well as the degree of\nspin-polarization of the SPHE current density responsible for the observed\nmagnetization dynamics. Our work finally characterizes the spin-polarization of\nthe SPHEs revealing unexpected opposite spin polarization to the Co\nmagnetization, explaining our experimental results.",
        "positive": "Is hydrogen diffusion in amorphous metals non-Arrhenian?: Hydrogen diffusion is critical to the performance of metals for hydrogen\nstorage as well as other important applications. As compared to its crystalline\ncounterpart which follows the Arrhenius relation, hydrogen diffusion in\namorphous metals sometimes are experimentally found to be non-Arrhenian. In\nthis work we studied the diffusion of hydrogen in amorphous Pd-H and Zr-Cu-H\nalloys based on molecular dynamics simulations. Our simulations confirm\nArrhenian diffusion behaviour for hydrogen in amorphous alloys, in contrast to\nprevious theoretical studies which predict non-Arrhenian behaviour. We show\nthat the simulated non-Arrhenian diffusion based on molecular dynamics could\nresult from a systematic error related to too short simulation time. We also\ndiscussed the experimental non-Arrhenian behaviour of hydrogen diffusion within\nthe framework of quantum tunneling and amorphous-amorphous phase\ntransformations."
    },
    {
        "anchor": "The Shockley-type boundary conditions for semiconductor p-n junctions at\n  medium and high injection levels: The classical Shockley boundary conditions are used for the determination of\nthe minority carrier concentrations at the edges of the space-charge region of\nsemiconductor p-n junctions. They are usually employed for the calculation of\nthe p-n junction current/ voltage characteristic. This work demonstrates that\nthey are valid only at low injection current levels. New analytical expressions\nfor these boundary conditions are obtained for medium and high injection\nlevels. These expressions are verified by calculating the current/ voltage\ncharacteristics of p-n junctions operated at high current levels.",
        "positive": "Euler-Rodrigues and Cayley formulas for rotation of elasticity tensors: It is fairly well known that rotation in three dimensions can be expressed as\na quadratic in a skew symmetric matrix via the Euler-Rodrigues formula. A\ngeneralized Euler-Rodrigues polynomial of degree 2n in a skew symmetric\ngenerating matrix is derived for the rotation matrix of tensors of order $n$.\nThe Euler-Rodrigues formula for rigid body rotation is recovered by n=1. A\nCayley form of the n-th order rotation tensor is also derived. The\nrepresentations simplify if there exists some underlying symmetry, as is the\ncase for elasticity tensors such as strain and the fourth order tensor of\nelastic moduli. A new formula is presented for the transformation of elastic\nmoduli under rotation: as a 21-vector with a rotation matrix given by a\npolynomial of degree 8. Explicit spectral representations are constructed from\nthree vectors: the axis of rotation and two orthogonal bivectors. The tensor\nrotation formulae are related to Cartan decomposition of elastic moduli and\nprojection onto hexagonal symmetry."
    },
    {
        "anchor": "Thermal boundary resistance at Si/Ge interfaces determined by\n  approach-to-equilibrium molecular dynamics simulations: The thermal boundary resistance of Si/Ge interfaces as been determined using\napproach-to-equilibrium molecular dynamics simulations. Assuming a reciprocal\nlinear dependence of the thermal boundary resistance, a length-independent bulk\nthermal boundary resistance could be extracted from the calculation resulting\nin a value of 3.76x10$^{-9}$ m$^2$ K/W for a sharp Si/Ge interface and thermal\ntransport from Si to Ge. Introducing an interface with finite thickness of 0.5\nnm consisting of a SiGe alloy, the bulk thermal resistance slightly decreases\ncompared to the sharp Si/Ge interface. Further growth of the boundary leads to\nan increase in the bulk thermal boundary resistance. When the heat flow is\ninverted (Ge to Si), the thermal boundary resistance is found to be higher.\nFrom the differences in the thermal boundary resistance for different heat flow\ndirection, the rectification factor of the Si/Ge has been determined and is\nfound to significantly decrease when the sharp interface is moderated by\nintroduction of a SiGe alloy in the boundary layer.",
        "positive": "Fluctuated spin-orbital texture of Rashba-split surface states in real\n  and reciprocal space: Spin-orbit interaction (SOI) in low-dimensional systems, namely Rashba\nsystems and the edge states of topological materials, is extensively studied in\nthis decade as a promising source to realize various fascinating spintronic\nphenomena, such as the source of the spin current and spin-mediated energy\nconversion. Here, we show the odd fluctuation in the spin-orbital texture in a\nsurface Rashba system on Bi/InAs(110)-(2$\\times$1) by spin- and angle-resolved\nphotoelectron spectroscopy and a numerical simulation based on a\ndensity-functional theory (DFT) calculation. The surface state shows a paired\nparabolic dispersion with the spin degeneracy lifted by the Rashba effect.\nAlthough its spin polarization should be fixed in a particular direction based\non the Rashba model, the observed spin polarization varies greatly and even\nreverses its sign depending on the wavenumber. DFT calculations also reveal\nthat the spin directions of two inequivalent Bi chains on the surface change\nfrom nearly parallel (canted-parallel) to anti-parallel in real space in the\ncorresponding wavevector region. These results point out an oversimplification\nof the nature of spin in Rashba and Dirac systems and provide more freedom than\nexpected for spin manipulation of photoelectrons."
    },
    {
        "anchor": "Superconductivity in Weyl Semimetal Candidate MoTe2: In recent years, layered transition-metal dichalcogenides (TMDs) have\nattracted considerable attention because of their rich physics; for example,\nthese materials exhibit superconductivity, charge density waves, and the valley\nHall effect. As a result, TMDs have promising potential applications in\nelectronics, catalysis, and spintronics. Despite the fact that the majority of\nrelated research focuses on semiconducting TMDs (e.g., MoS2), the\ncharacteristics of WTe2 are provoking strong interest in semimetallic TMDs with\nextremely large magnetoresistance, pressure-driven superconductivity, and the\npredicted Weyl semimetal (WSM) state. In this work, we investigate the sister\ncompound of WTe2, MoTe2, which is also predicted to be a WSM and a quantum spin\nHall insulator in bulk and monolayer form, respectively. We find that MoTe2\nexhibits superconductivity with a resistive transition temperature Tc of 0.1 K.\nThe application of a small pressure (such as 0.4 GPa) is shown to dramatically\nenhance the Tc, with a maximum value of 8.2 K being obtained at 11.7 GPa (a\nmore than 80-fold increase in Tc). This yields a dome-shaped superconducting\nphase diagram. Further explorations into the nature of the superconductivity in\nthis system may provide insights into the interplay between strong correlations\nand topological physics.",
        "positive": "Strain-induced magnetism in MoS2 monolayer with defects: The strain-induced magnetism is observed in single-layer MoS2 with atomic\nsingle vacancies from density functional calculations. Calculated magnetic\nmoment is no less than 2muB per vacancy defect. The straininduced band gap\nclosure is concurrent with the occurrence of the magnetism. Possible physical\nmechanism of the emergence of strain-induced magnetism is illustrated. We also\ndemonstrate the possibility to test the predicted magnetism in experiment. Our\nstudy may provide an opportunity for the design of new type of memory-switching\nor logic devices by using earth-rich nonmagnetic materials MoS2."
    },
    {
        "anchor": "Ultrathin catalyst-free InAs nanowires on silicon with distinct 1D\n  sub-band transport properties: Ultrathin InAs nanowires (NW) with one-dimensional (1D) sub-band structure\nare promising materials for advanced quantum-electronic devices, where\ndimensions in the sub-30 nm diameter limit together with post-CMOS integration\nscenarios on Si are much desired. Here, we demonstrate two site-selective\nsynthesis methods that achieve epitaxial, high aspect ratio InAs NWs on Si with\nultrathin diameters below 20 nm. The first approach exploits direct vapor-solid\ngrowth to tune the NW diameter by interwire spacing, mask opening size and\ngrowth time. The second scheme explores a unique reverse-reaction growth by\nwhich the sidewalls of InAs NWs are thermally decomposed under controlled\narsenic flux and annealing time. Interesting kinetically limited dependencies\nbetween interwire spacing and thinning dynamics are found, yielding diameters\nas low as 12 nm for sparse NW arrays. We clearly verify the 1D sub-band\nstructure in ultrathin NWs by pronounced conductance steps in low-temperature\ntransport measurements using back-gated NW-field effect transistors. Correlated\nsimulations reveal single- and double degenerate conductance steps, which\nhighlight the rotational hexagonal symmetry and reproduce the experimental\ntraces in the diffusive 1D transport limit. Modelling under the realistic\nback-gate configuration further evidences regimes that lead to asymmetric\ncarrier distribution and lifts of the degeneracy in dependence of gate bias.",
        "positive": "Datasets on materials research of hard ferromagnet in TM-Fe-Si (TM=Ti,\n  Zr, Hf, V, Nb, and Ta) ternary systems: The datasets presented in this article are related to materials research on\nhard ferromagnet in TM-Fe-Si (TM=Ti, Zr, Hf, V, Nb, and Ta) ternary systems.\nThe motivation for data collection is based on the research paper entitled\n\"Novel hard magnetic phase with Zr$_{11.5}$Fe$_{53}$Si$_{35.5}$ composition\".\nThe datasets are composed of scanning electron microscope images, X-ray\ndiffraction (XRD) patterns, and magnetization data for\nTM$_{7}$Fe$_{52}$Si$_{41}$ annealed at 1050 $^{\\circ}$C. The chemical\ncompositions of constituent phases were determined by an energy dispersive\nX-ray spectrometer (EDS). The phase analysis was performed using XRD and EDS\nresults. The Curie temperature of each sample was obtained using magnetization\ndata, and the coercive field was determined for hard ferromagnet samples\nZr$_{7}$Fe$_{52}$Si$_{41}$ and Hf$_{7}$Fe$_{52}$Si$_{41}$. The datasets would\nbe useful for developing an Fe-based rare-earth-free permanent magnet, which is\none of the central issues of materials science."
    },
    {
        "anchor": "Magneto-impedance of glass-coated Fe-Ni-Cu microwires: The magneto-impedance (MI) of glass-coated Fe-Ni-Cu microwires was\ninvestigated for longitudinal radio-frequency (RF) currents up to a frequency\nof 200 MHz using an RF lock-in amplifier method. The MI, defined as DZ/Z =\n[Z(H)-Z(H=0.3T)]/Z(H=0.3T), displays a peak structure (negative MI) at zero\nfield for RF currents with frequencies less than 20MHz and this crosses over to\na sharp dip (positive MI) at higher frequencies. This crossover behavior is\nascribed to the skin-depth-limited response primarily governed by the\nfield-dependence of the permeability. Large saturation fields (300 to 600 Oe)\nand other anomalies indicate the possible influence of giant magneto-resistance\n(GMR) on the MI.",
        "positive": "Deciphering mechanisms of enhanced-retarded oxygen diffusion in doped Si: In this letter, we study enhanced-retarded diffusion of oxygen in doped\nsilicon by means of first principle calculations. We found that the migration\nof oxygen dimers can not be significantly affected by strain, doping type or\nrate. We attribute the enhanced oxygen diffusion in p-doped silicon to reduced\nmonomer migration energy, and the retarded oxygen diffusion in Sb-doped to\noxygen trapping close to a dopant site. The two proposed kinetic and\nthermodynamic mechanisms can appear at the same time and might lead to\ncontradictory experimental results. Such mechanisms can be involved in the\nlight induced degradation phenomenon in solar grade silicon."
    },
    {
        "anchor": "Magnon dispersion in bilayers of two-dimensional ferromagnets: We determine magnon spectra of an atomic bilayer magnet with ferromagnetic\nintra- and both ferro- and anti- ferromagnetic interlayer coupling. Analytic\nexpressions for the full magnon band of the latter case reveal that both\nexchange interactions govern the fundamental magnon gap. The inter and\nintralayer magnetic ordering are not independent: the intralayer ferromagnetism\nstabilizes antiferromagnetic inter-layer order. The topology of these\nexchange-anisotropy spin models without spin-orbit interaction turns out to be\ntrivial.",
        "positive": "Dynamics of elastic boundaries: We study, both analytically and numerically, the dynamics of elastic\nboundaries such as crack fronts in fracture and surfaces of contact in solid on\nsolid friction. The elastic waves in the solid give rise to kinks that move\nwith a characteristic velocity along the boundary. As stopping kinks pass\nthrough they cause moving parts of the boundary to stop. Starting kinks cause\nstationary parts of the boundary to move. We study the interaction of these\nkinks with disorder that arises from the spatial variations of the friction\nconstant or fracture energy. In the absence of elastic waves, elastic\nboundaries with disorder operate at a critical point leading to a power-law\ndistribution of slip events and self-affine boundaries. Elastic waves result in\nrelevant perturbations at this fixed point. Slip events beyond a critical size\nrun away and the velocity of the boundary jumps to a nonzero value when the\nexternal load is increased above a threshold. We analyze in detail a class of\nsimple models that capture the essential features of bulk vectorial elasticity\nand discuss the implications of our results for friction and fracture dynamics."
    },
    {
        "anchor": "Carrier-induced ferromagnetism in p-Zn1-xMnxTe: We present a systematic study of the ferromagnetic transition induced by the\nholes in nitrogen doped Zn1-xMnxTe epitaxial layers, with particular emphasis\non the values of the Curie-Weiss temperature as a function of the carrier and\nspin concentrations. The data are obtained from thorough analyses of the\nresults of magnetization, magnetoresistance and spin-dependent Hall effect\nmeasurements. The experimental findings compare favorably, without adjustable\nparameters, with the prediction of the Rudermann-Kittel-Kasuya-Yosida (RKKY)\nmodel or its continuous-medium limit, that is, the Zener model, provided that\nthe presence of the competing antiferromagnetic spin-spin superexchange\ninteraction is taken into account, and the complex structure of the valence\nband is properly incorporated into the calculation of the spin susceptibility\nof the hole liquid. In general terms, the findings demonstrate how the\ninterplay between the ferromagnetic RKKY interaction, carrier localization, and\nintrinsic antiferromagnetic superexchange affects the ordering temperature and\nthe saturation value of magnetization in magnetically and electrostatically\ndisordered systems.",
        "positive": "Vibrational behaviour of a realistic amorphous-silicon model: The vibrational properties of a high-quality realistic model of amorphous\nsilicon are examined. The longitudinal and transverse dynamical structure\nfactors are calculated, and fitted to a damped harmonic oscillator (DHO)\nfunction. The width $\\Gamma$ of the best-fit DHO to the longitudinal dynamical\nstructure factor scales approximately as $k^{2}$ for wavevectors\n$k\\lesssim0.55\\textrm{\\AA}^{-1}$, which is above the Ioffe-Regel crossover\nfrequency separating the propagating and diffusing regimes, occurring at\n$k=0.38\\pm0.03\\textrm{\\AA}^{-1}$. Using the DHO function as a fitting function\nfor the transverse dynamical structure factor (without theoretical\njustification), gives a dependence of $\\Gamma\\propto k^{\\alpha}$ with\n$\\alpha\\sim2.5$ for wavevectors $k\\lesssim0.7\\textrm{\\AA}^{-1}$. There was no\nevidence for $\\Gamma\\propto k^{4}$ behaviour for either polarization."
    },
    {
        "anchor": "Impact of biaxial and uniaxial strain on V$_2$O$_3$: Using first-principles calculations we determine the role of compressive and\ntensile uniaxial and equibiaxial strain on the structural, electronic and\nmagnetic properties of V$_2$O$_3$. We find that compressive strain increases\nthe energy cost to transition from the high-temperature paramagnetic metallic\nphase to the low-temperature antiferromagnetic insulating phase. This shift in\nthe energy difference can be explained by changes in the V-V bond lengths that\nare antiferromagnetically aligned in the low temperature structure. The\ninsights that we have obtained provide a microscopic explanation for the shifts\nin the metal-insulator transition temperature that have been observed in\nexperiments of V$_2$O$_3$ films grown on different substrates.",
        "positive": "High resolution electron microscopy for heterogeneous catalysis research: Heterogeneous catalysts are the most important catalysts in industrial\nreactions. Nanocatalysts, with size ranging from hundreds of nanometers to the\natomic scale, possess activities that are closely connected to their structural\ncharacteristics such as particle size, surface morphology, and\nthree-dimensional topography. Recently, the development of advanced analytical\ntransmission electron microscopy (TEM) techniques, especially quantitative\nhigh-angle annular dark-field (HAADF) imaging and high-energy resolution\nspectroscopy analysis in scanning transmission electron microscopy (STEM) at\nthe atomic scale, strengthens the power of (S)TEM in analyzing the\nstructural/chemical information of heterogeneous catalysts. Three-dimensional\nreconstruction from two-dimensional projected images and the real-time\nrecording of structural evolution during catalytic reactions using in-situ\n(S)TEM methods further broaden the scope of (S)TEM observation. The\natomic-scale structural information obtained from high resolution (S)TEM has\nproven to be of significance for better understanding and designing of new\ncatalysts with enhanced performance."
    },
    {
        "anchor": "Per-grain and neighbourhood stress interactions during deformation of a\n  ferritic steel obtained using three-dimensional X-ray diffraction: Three-dimensional X-ray diffraction (3DXRD) has been used to measure,\nin-situ, the evolution of $\\sim 1800$ grains in a single phase low carbon\nferritic steel sample during uniaxial deformation. The distribution of initial\nresidual grain stresses in the material was observed to prevail as plasticity\nbuilds, though became less pronounced, and therefore less influential as strain\nincreased. The initial Schmid factor of a grain was found to be strongly\ncorrelated to the intergranular stress change and the range of stresses that\nare permissible; a grain well aligned for easy slip is more likely to exhibit a\nrange of stresses than those orientated poorly for dislocation motion. The\norientation path of a grain, however, is not only dependent on its initial\norientation, but hypothesised to be influenced by its stress state and the\nstress state of its grain environment. A grain neighbourhood effect is\nobserved: the Schmid factor of serial adjoining grains influences the stress\nstate of a grain of interest, whereas parallel neighbours are much less\ninfluential. This phenomenon is strongest at low plastic strains only, with the\neffect diminishing as plasticity builds. The influence of initial residual\nstresses becomes less evident, and grains rotate to eliminate any orientation\ndependent load shedding. The ability of the BCC ferrite to exhaust such\nneighbourhood interactions, which would otherwise be detrimental in crystal\nstructures with lower symmetric and fewer slip systems, is considered key to\nthe high ductility possessed by these materials.",
        "positive": "Adaptation of a commercial Raman spectrometer for multiline and\n  broadband laser operation: A commercial single laser line Raman spectrometer is modified to accommodate\nmultiline and tunable dye lasers, thus combining the high sensitivity of such\nsingle monochromator systems with broadband operation. Such instruments rely on\nhigh-throughput interference filters that perform both beam alignment and\nRayleigh filtering. Our setup separates the dual task of the built-in\nmonochromator into two independent elements: a beam splitter and a long pass\nfilter. Filter rotation shifts the transmission passband, effectively expanding\nthe range of operation. Rotation of the filters has a negligible effect on the\noptical path, allowing broadband operation and stray light rejection down to\n70-150 1/cm. Operation is demonstrated on single-walled carbon nanotubes, for\nwhich the setup was optimized."
    },
    {
        "anchor": "Effect of strain and doping on the polar metal phase in LiOsO$_3$: We systematically investigate the effect of strain and doping on the polar\nmetal phase in lithium osmate, LiOsO$_3$, using first-principles calculations.\nWe demonstrate that the polar metal phase in LiOsO$_3$ can be controlled by\nbiaxial strain. Based on density functional calculations, we show that a\ncompressive biaxial strain enhances the stability of the polar $R3c$ phase. On\nthe other hand, a tensile biaxial strain favors the centrosymmetric\n$R\\overline{3}c$ structure. Thus, strain emerges as a promising control\nparameter over polar metallicity in this material. We uncover a strain-driven\nquantum phase transition under tensile strain, and highlight intriguing\nproperties that could emerge in the vicinity of this polar to non-polar metal\ntransition. We examine the effect of charge doping on the polar metal phase. By\nmeans of electrostatic doping as well as supercell calculations, we find that\nscreening from additional charge carriers, expected to suppress the polar\ndistortions, have only a small effect on them. Rather remarkably, and in\ncontrast to conventional ferroelectrics, the polar metal phase in LiOsO$_3$\nremains robust against charge doping up to large doping values.",
        "positive": "Direct Measurement of Magnetocaloric Effect in Metamagnetic\n  Ni43Mn37.9In12.1Co7 Heusler Alloy: The magnetocaloric effect in the metamagnetic Ni43Mn37.9In12.1Co7 Heusler\nalloy is directly studied experimentally under the adiabatic and\nquasi-isothermal conditions in a magnetic field with induction of up to 14 T."
    },
    {
        "anchor": "Comparison of two methods for describing the strain profiles in quantum\n  dots: The electronic structure of interfaces between lattice-mismatched\nsemiconductor is sensitive to the strain. We compare two approaches for\ncalculating such inhomogeneous strain -- continuum elasticity (CE, treated as a\nfinite difference problem) and atomistic elasticity (AE). While for small\nstrain the two methods must agree, for the large strains that exist between\nlattice-mismatched III-V semiconductors (e.g. 7% for InAs/GaAs outside the\nlinearity regime of CE) there are discrepancies. We compare the strain profile\nobtained by both approaches (including the approximation of the correct C_2\nsymmetry by the C_4 symmetry in the CE method), when applied to C_2-symmetric\nInAs pyramidal dots capped by GaAs.",
        "positive": "Optical Phonons in Carbon Nanotubes: Kohn Anomalies, Peierls Distortions\n  and Dynamic Effects: We present a detailed study of the vibrational properties of Single Wall\nCarbon Nanotubes (SWNTs). The phonon dispersions of SWNTs are strongly shaped\nby the effects of electron-phonon coupling. We analyze the separate\ncontributions of curvature and confinement. Confinement plays a major role in\nmodifying SWNT phonons and is often more relevant than curvature. Due to their\none-dimensional character, metallic tubes are expected to undergo Peierls\ndistortions (PD) at T=0K. At finite temperature, PD are no longer present, but\nphonons with atomic displacements similar to those of the PD are affected by\nstrong Kohn anomalies (KA). We investigate by Density Functional Theory (DFT)\nKA and PD in metallic SWNTs with diameters up to 3 nm, in the electronic\ntemperature range from 4K to 3000 K. We then derive a set of simple formulas\naccounting for all the DFT results. Finally, we prove that the static approach,\ncommonly used for the evaluation of phonon frequencies in solids, fails because\nof the SWNTs reduced dimensionality. The correct description of KA in metallic\nSWNTs can be obtained only by using a dynamical approach, beyond the adiabatic\nBorn-Oppenheimer approximation, by taking into account non-adiabatic\ncontributions. Dynamic effects induce significant changes in the occurrence and\nshape of Kohn anomalies. We show that the SWNT Raman G peak can only be\ninterpreted considering the combined dynamic, curvature and confinement\neffects. We assign the G+ and G- peaks of metallic SWNTs to TO\n(circumferential) and LO (axial) modes, respectively, the opposite of\nsemiconducting SWNTs."
    },
    {
        "anchor": "Methanol adsorption on graphene: The adsorption energies and orientation of methanol on graphene are\ndetermined from first-principles density functional calculations. We employ the\nwell-tested vdW-DF method that seamlessly includes dispersion interactions with\nall of the more close-ranged interactions that result in bonds like the\ncovalent and hydrogen bonds. The adsorption of a single methanol molecule and\nsmall methanol clusters on graphene are studied at various coverages.\nAdsorption in clusters or at high coverages (less than a monolayer) is found to\nbe preferable, with the methanol C-O axis approximately parallel to the plane\nof graphene. The adsorption energies calculated with vdW-DF are compared with\nprevious DFT-D and MP2-based calculations for single methanol adsorption on\nflakes of graphene (polycyclic aromatic hydrocarbons). For the high coverage\nadsorption energies we also find reasonably good agreement with previous\ndesorption measurements.",
        "positive": "Micrometer-scale monolayer SnS growth by physical vapor deposition: Recently, monolayer SnS, a two-dimensional group IV monochalcogenide, was\ngrown on a mica substrate at the micrometer-size scale by the simple physical\nvapor deposition (PVD), resulting in the successful demonstration of its\nin-plane room temperature ferroelectricity. However, the reason behind the\nmonolayer growth remains unclear because it had been considered that the SnS\ngrowth inevitably results in a multilayer thickness due to the strong\ninterlayer interaction arising from lone pair electrons. Here, we investigate\nthe PVD growth of monolayer SnS from two different feed powders, highly\npurified SnS and commercial phase-impure SnS. Contrary to expectations, it is\nsuggested that the mica substrate surface is modified by sulfur evaporated from\nthe Sn2S3 contaminant in the as-purchased powder and the lateral growth of\nmonolayer SnS is facilitated due to the enhanced surface diffusion of SnS\nprecursor molecules, unlike the growth from the highly purified powder. This\ninsight provides a guide to identify further controllable growth conditions."
    },
    {
        "anchor": "Role of coil-crucible geometry in Czochralski bismuth germanate (BGO)\n  crystal growth process: a thermal stress analysis: A numerical model of 2D finite element in a steady-state level was developed\nfor the electromagnetic field, heat distribution, and thermal stress expansion\nin an oxide Czochralski crystal growth system. The extended model was employed\nto compare the impact of different geometries of induction coils and crucibles\nin the growth process. Analysis of the results emphasizes the potential of the\nmodified geometries in alteration of the electromagnetic field and heat\ndistribution. Consequently, the optimization of crystal/melt interface shape,\nthermal stress accumulation, and distribution in the growing crystal can be\nachieved. Finally, the proposed approaches for thermal stress calculations were\ncompared. The outcomes showed a qualitative agreement between two methods of\nthermoelastic stress analysis in the calculation of stress distribution in BGO\ncrystal.",
        "positive": "Skyrmionics in correlated oxides: While chiral magnets, metal-based magnetic multilayers, or Heusler compounds\nhave been considered as the material workhorses in the field of skyrmionics,\noxides are now emerging as promising alternatives, as they host special\ncorrelations between the spin-orbital-charge-lattice degrees of freedom and/or\ncoupled ferroic order parameters. These interactions open new possibilities for\npractically exploiting skyrmionics. In this article, we review the recent\nadvances in the observation and control of topological spin textures in various\noxide systems. We start with the discovery of skyrmions and related\nquasiparticles in bulk and heterostructure ferromagnetic oxides. Next, we\nemphasize the shortcomings of implementing ferromagnetic textures, which have\nled to the recent explorations of ferrimagnetic and antiferromagnetic oxide\ncounterparts, with higher Curie temperatures, stray-field immunity, low Gilbert\ndamping, ultrafast magnetic dynamics, and/or absence of skyrmion deflection.\nThen, we highlight the development of novel pathways to control the stability,\nmotion, and detection of topological textures using electric fields and\ncurrents. Finally, we present the outstanding challenges that need to be\novercome to achieve all-electrical, nonvolatile, low-power oxide skyrmionic\ndevices."
    },
    {
        "anchor": "Onsager's Wien Effect on a Lattice: The Second Wien Effect describes the non-linear, non-equilibrium response of\na weak electrolyte in moderate to high electric fields. Onsager's 1934\nelectrodiffusion theory along with various extensions has been invoked for\nsystems and phenomena as diverse as solar cells, surfactant solutions, water\nsplitting reactions, dielectric liquids, electrohydrodynamic flow, water and\nice physics, electrical double layers, non-Ohmic conduction in semiconductors\nand oxide glasses, biochemical nerve response and magnetic monopoles in spin\nice. In view of this technological importance and the experimental ubiquity of\nsuch phenomena, it is surprising that Onsager's Wien effect has never been\nstudied by numerical simulation. Here we present simulations of a lattice\nCoulomb gas, treating the widely applicable case of a double equilibrium for\nfree charge generation. We obtain detailed characterisation of the Wien effect\nand confirm the accuracy of the analytical theories as regards the field\nevolution of the free charge density and correlations. We also demonstrate that\nsimulations can uncover further corrections, such as how the field-dependent\nconductivity may be influenced by details of microscopic dynamics. We conclude\nthat lattice simulation offers a powerful means by which to investigate\nsystem-specific corrections to the Onsager theory, and thus constitutes a\nvaluable tool for detailed theoretical studies of the numerous practical\napplications of the Second Wien Effect.",
        "positive": "Direct observation of Dirac states in Bi2Te3 nanoplatelets by 125Te NMR: Detection of the metallic Dirac electronic states on the surface of\nTopological Insulators (TIs) is a tribune for a small number of experimental\ntechniques the most prominent of which is Angle Resolved Photoemission\nSpectroscopy. However, there is no experimental method showing at atomic scale\nresolution how the Dirac electrons extend inside TI systems. This is a critical\nissue in the study of important surface quantum properties, especially\ntopological quasiparticle excitations. Herein, by applying advanced\nDFT-assisted solid-state 125Te Nuclear Magnetic Resonance on Bi2Te3\nnanoplatelets, we succeeded in uncovering the hitherto invisible NMR signals\nwith magnetic shielding influenced by the Dirac electrons, and subsequently\nshowed how Dirac electrons spread and interact with the bulk interior of the\nnanoplatelets."
    },
    {
        "anchor": "Comparison of the use of NiFe and CoFe as electrodes for metallic\n  lateral spin-valves: Spin injection and detection in Co60Fe40-based all-metallic lateral\nspin-valves have been studied at both room and low temperatures. The obtained\nspin signals amplitudes have been compared to that of identical Ni80Fe20-based\ndevices. The replacement of Ni80Fe20 by CoFe allows increasing the spin signal\namplitude by up to one order of magnitude, thus reaching 50 m{\\Omega} at room\ntemperature. The spin signal dependence with the distance between the\nferromagnetic electrodes has been analyzed using both a 1D spin transport model\nand finite elements method simulations. The enhancement of the spin signal\namplitude when using CoFe electrodes can be explained by a higher effective\npolarization.",
        "positive": "Microstructure-dependent oxidation-assisted dealloying of Cu0.7Al0.3\n  thin films: In this paper, the oxidation-assisted dealloying (OAD) of Cu0.7Al0.3 films\nwith different microstructures which were obtained by high vacuum annealing at\ndifferent temperatures were studied using powder X-ray diffraction,\nfield-emission scanning electron microscopy and energy dispersive X-ray\nanalysis. It was observed that different microstructures such as eutectic\nmixture or solid solution, the grain size of Cu or Al component in\neutectic-mixture Cu0.7Al0.3 films affected the corrosion morphology greatly. It\nthus provided a practical route to fabricate flexible CuO porous\nnanostructure-films (PNFs) with controllable pore size, porosity, block size\nand shape. Further, the underlying OAD mechanisms for the structure-resultant\ndifferent corrosion morphologies of Cu0.7Al0.3 films were also explored. In\nthese senses, the study is suggestive and crucial to both the mechanism\nunderstanding of OAD process and the technical controlling of PNF fabrication."
    },
    {
        "anchor": "Single-Molecule Magnets: Preparation and Properties of Mixed-Carboxylate\n  Complexes [Mn12O12(O2CR)8(O2CR')8(H2O)4]: Methods are reported for the preparation of mixed-carboxylate versions of the\n[Mn12O12(O2CR)16(H2O)4] family of single-molecule magnets (SMMs).\n[Mn12O12(O2CCHCl2)8(O2CCH2But)8(H2O)3] (5) and\n[Mn12O12(O2CHCl2)8(O2CEt)8(H2O)3] (6) have been obtained from the 1:1 reaction\nof the corresponding homocarboxylate species. Complexes 5 and 6 both contain a\n[Mn12O12] core with the CHCl2CO2- ligands ordered in the axial positions and\nthe RCO2- ligands (R = CH2But (5) or Et (6)) in equatorial positions. There is,\nthus, a preference for the CHCl2CO2- to occupy the sites lying on the MnIII\nJahn-Teller axes, and this is rationalized on the basis of the relative\nbasicities of the carboxylate groups. Direct current magnetic susceptibility\nstudies in a 10.0 kG field in the 2.00-300 K range indicate a large\nground-state spin, and fitting of magnetization data collected in the 10.0-70.0\nkG field and 1.80-4.00 K temperature range gave S = 10, g = 1.89, and D = -0.65\nK for 5, and S = 10, g = 1.83, and D = -0.60 K for 6. These values are typical\nof [Mn12O12(O2CR)16(H2O)4] complexes. Alternating current susceptibility\nstudies show the out-of-phase susceptibility (chi'') signals characteristic of\nthe slow relaxation in the millisecond time scale of single-molecule magnets.\nArrhenius plots obtained from chi'' versus T data gave effective barriers to\nrelaxation (Ueff) of 71 and 72 K for 5 and 6, respectively. 1H NMR spectra in\nCD2Cl2 show that 5 and 6 are the main species present on dissolution, but there\nis evidence for some ligand distribution between axial and equatorial sites, by\nintra- and/or intermolecular exchange processes.",
        "positive": "Dynamic plasticity of beryllium in the inertial fuel fusion capsule\n  regime: The plastic response of beryllium was investigated during loading by\nlaser-induced shock waves, using surface velocimetry and in-situ x-ray\ndiffraction. Results from loading by thermal x-rays (hohlraum) were consistent\nwith more extensive studies using laser ablation. Strong elastic waves were\nobserved, up to ~1 km/s in free surface speed, with significant structure\nbefore the arrival of the plastic shock. The magnitude and shape of the\nprecursor could be reproduced with a plasticity model based on dislocation\ndynamics. Changes in lattice spacing measured from the x-ray diffraction\npattern gave a direct measurement of uniaxial compression in the elastic wave,\ntriaxial flow from the decay of the precursor, and triaxial compression in the\nplastic shock; these were consistent with the velocity data. The dynamic\nstrength behavior deduced from the laser experiments was used to help interpret\nsurface velocity data around the onset of shock-induced melting. A model of\nheterogeneous mixtures is being extended to treat anisotropic components, and\nspall."
    },
    {
        "anchor": "Determination of the graphene growth mode on SiC(0001) and SiC(000-1): We have determined the growth mode of graphene on SiC(0001) and SiC(000-1)\nusing ultra-thin, isotopically-labeled Si13C `marker layers' grown epitaxially\non the Si12C surfaces. Few-layer graphene overlayers were formed via thermal\ndecomposition at elevated temperature. For both surface terminations (Si-face\nand C-face), we find that the 13C is located mainly in the outermost graphene\nlayers, indicating that, during decomposition, new graphene layers form\nunderneath existing ones.",
        "positive": "Electrochemical integration of graphene with light absorbing\n  copper-based thin films: We present an electrochemical route for the integration of graphene with\nlight sensitive copper-based alloys used in optoelectronic applications.\nGraphene grown using chemical vapor deposition (CVD) transferred to glass is\nfound to be a robust substrate on which photoconductive Cu_{x}S films of 1-2 um\nthickness can be deposited. The effect of growth parameters on the morphology\nand photoconductivity of Cu_{x}S films is presented. Current-voltage\ncharacterization and photoconductivity decay experiments are performed with\ngraphene as one contact and silver epoxy as the other."
    },
    {
        "anchor": "Intrinsic Localized Lattice Modes and Thermal Transport: Potential\n  Application in a Thermal Rectifier: Recent experiments provide evidence of intrinsic localized modes (ILMs) in\nthe lattice dynamics of conventional 3D materials. Here evidence that ILMs in\nuranium metal enhance the thermal conductivity is presented along with\nspeculation on how thermal transport by ILMs might be used to improve a\nreported design for a solid-state thermal rectifier.",
        "positive": "The origins of electromechanical indentation size effect in\n  ferroelectrics: Metals exhibit a size-dependent hardening when subject to indentation.\nMechanisms for this phenomenon have been intensely researched in recent times.\nDoes such a size-effect also exist in the electromechanical behavior of\nferroelectrics?--if yes, what are the operative mechanisms? Our experiments on\nBaTiO3 indeed suggest an electromechanical size-effect. We argue, through\ntheoretical calculations and differential experiments on another\nnon-ferroelectric piezoelectric (Quartz), that the phenomenon of\nflexoelectricity(as opposed to dislocation activity) is responsible for our\nobservations. Flexoelectricity is the coupling of strain gradients to\npolarization and exists in both ordinary and piezoelectric dielectrics. In\nparticular, ferroelectrics exhibit an unusually large flexoelectric response."
    },
    {
        "anchor": "Half-metallicity and anisotropy magnetoresistance properties of Heusler\n  alloys Fe2Co1-xCrxSi: In this paper, we investigate the half-metallicity of Heusler alloys\nFe2Co1-xCrxSi by first principles calculations and anisotropy magnetoresistance\nmeasurements. It is found that, with the increase of Cr content x, the Fermi\nlevel of Fe2Co1-xCrxSi moves from the top of valence band to the bottom of\nconduction band, and a large half-metallic band gap of 0.75 eV is obtained for\nx=0.75. We then successfully synthesized a series Heusler Fe2Co1-xCrxSi\npolycrystalline ribbon samples. The results of X-ray diffraction indicate that\nthe Fe2Co1-xCrxSi series of samples are pure phase with a high degree of order\nand the saturation magnetic moment follows half-metallic Slater-Pauling rule.\nExcept for the two end members, Fe2CoSi and Fe2CrSi, the anisotropic\nmagnetoresistance of Fe2Co1-xCrxSi (x=0.25, 0.5, 0.75) show a negative value\nsuggesting they are stable half-metallic ferromagnets.",
        "positive": "Electronic properties of Cs-based halide perovskites: An ab-initio study: Halide perovskites consist a class of materials under intense investigation\ndue to their potential technological applications like solar cells,\noptoelectronic devices and catalysis. Recently we have studied using electronic\nband structure calculations from first principles, the cubic MABX$_3$ compounds\n[A. Koliogiorgos et al., Comput. Mater. Sci. \\textbf{138}, 92 (2017)], where MA\nstands for the methylammonium cation, B is a divalent cation and X a halogen.\nWe expand our study in the case where Cs stands in place of the MA cation. Our\nresults suggest that the Cs-based compounds exhibit also a variety of lattice\nconstants and energy band gaps. The calculated equilibrium lattice constants\ndiffer substantially from the experimental ones. The calculated energy gaps\nalso show large deviations for these lattice constants. Moreover, the use of\nmore sophisticated functionals leads to conflicting changes in the energy gap\nvalues and its effect is materials dependent. Our results suggest that contrary\nto the MA halide perovskites, the Cs halide perovskites consist a more delicate\ncase and there is still a long way for \\textit{ab-initio} calculations to\naccurate describe their structural and electronic properties."
    },
    {
        "anchor": "New features of dislocation structures arising from lattice discreteness: New aspects of a relation between lattice and dislocation structures are\nexamined within a physically transparent theoretical scheme. Predicted features\noriginating from the lattice discreteness include: (i) multiple core\ndislocation structures and (ii) their dependence on the position of the\ndislocation axis. These effects, which in principle can be observed directly\nand may also manifest themselves in dislocation motion or/and transformation\n(cross-slip) characteristics, are very general and present in any crystal in\nwhich they may be more or less pronounced depending on the material.",
        "positive": "Kinematics of slip-induced rotation for uniaxial shock or ramp\n  compression: When a metallic specimen is plastically deformed, its underlying crystal\nstructure must often rotate in order to comply with its macroscopic boundary\nconditions. There is growing interest within the dynamic compression community\nin exploiting x-ray diffraction measurements of lattice rotation to infer which\ncombinations of plasticity mechanisms are operative in uniaxially shock- or\nramp-compressed crystals, thus informing materials science at the greatest\nextremes of pressure and strain rate. However, it is not widely appreciated\nthat several of the existing models linking rotation to slip activity are\nfundamentally inapplicable to a planar compression scenario. We present\nmolecular dynamics simulations of single crystals suffering true uniaxial\nstrain, and show that the Schmid and Taylor analyses used in traditional\nmaterials science fail to predict the ensuing lattice rotation. We propose a\nsimple alternative framework based on the elastoplastic decomposition that\nsuccessfully recovers the observed rotation for these single crystals, and can\nfurther be used to identify the operative slip systems and the amount of\nactivity upon them in the idealized cases of single and double slip."
    },
    {
        "anchor": "Closest Wannier functions to a given set of localized orbitals: A non-iterative method is presented to calculate the closest Wannier\nfunctions (CWFs) to a given set of localized guiding functions, such as atomic\norbitals, hybrid atomic orbitals, and molecular orbitals, based on minimization\nof a distance measure function. It is shown that the minimization is directly\nachieved by a polar decomposition of a projection matrix via singular value\ndecomposition, making iterative calculations and complications arising from the\nchoice of the gauge irrelevant. The disentanglement of bands is inherently\naddressed by introducing a smoothly varying window function and a greater\nnumber of Bloch functions, even for isolated bands. In addition to atomic and\nhybrid atomic orbitals, we introduce embedded molecular orbitals in molecules\nand bulks as the guiding functions, and demonstrate that the Wannier\ninterpolated bands accurately reproduce the targeted conventional bands of a\nwide variety of systems including Si, Cu, the TTF-TCNQ molecular crystal, and a\ntopological insulator of Bi$_2$Se$_3$. We further show the usefulness of the\nproposed method in calculating effective atomic charges. These numerical\nresults not only establish our proposed method as an efficient alternative for\ncalculating WFs, but also suggest that the concept of CWFs can serve as a\nfoundation for developing novel methods to analyze electronic structures and\ncalculate physical properties.",
        "positive": "Few-layer flakes of Molybdenum Disulphide produced by anodic arc\n  discharge in pulsed mode: Here, the synthesis of Molybdenum Disulphide (MoS2) flakes by means of anodic\natmospheric arc discharge is reported for the first time. The vertical\nelectrode configuration consisted of a compound anode (hollow graphite anode\nfilled with MoS2 powder) and a solid graphite cathode placed just above of the\ncompound anode. Arc processes were operated in pulsed mode to preferentially\nevaporate the powder component from the anode and to minimize Carbon ablation.\nPulsed anodic arc discharges were conducted at 2 Hz and 10% duty cycle in 300\nTorr of Helium with a peak current of 250-300 A and peak voltage of 35 V. A\nprobe made of Tungsten wire was placed in the vicinity of the arc column to\ncollect the evaporated material. The measured thickness profile was correlated\nto the particle flux distribution and it was fitted by a simple model of plasma\nexpansion. During pulse phase, electron density was estimated around 5E22 m-3\nor higher, and ion current density was of the order of 10 A/mm2. Morphology,\nstructure and composition of the samples were characterized by Raman\nspectroscopy, atomic force microscopy (AFM), scanning electron microscopy\n(SEM), transmission electron microscopy (TEM), and x-ray diffraction (XRD). The\nstudy shows that pulsed arc discharge of the compound anode leads to moderate C\ndeposition combined with MoS2 deposition in the form of fragmented nanocrystals\nand few atomic monolayers of MoS2. Such synthesis technique is promising to\nproduce new 2D nanomaterials with tailored structure and functionality thanks\nto the flexibility of pulsed power."
    },
    {
        "anchor": "Effect of W and Mo co-doping on the photo- and thermally stimulated\n  luminescence and defects creation processes in Gd3(Ga,Al)5O12:Ce crystals: Photo- and thermally stimulated luminescence characteristics of\nGd3(Ga,Al)5O12:Ce single crystals co-doped with W and Mo are investigated in\nthe 85 - 510 K temperature range and compared with the corresponding\ncharacteristics of the undoped and Ce3+ - doped Gd3(Ga,Al)5O12 single crystals\nof similar composition. A strong effect of the W and Mo impurity ions appears\nin the photoluminescence spectra and temperature dependences of the\nphotoluminescence intensity, afterglow intensity and decay kinetics, thermally\nstimulated luminescence (TSL) intensity and TSL glow curves, excitation spectra\nof the TSL glow curve peaks and activation energy of their creation. The\nobtained results are explained by the enhancement of the intrinsic emission\ncontribution into the luminescence spectrum of Gd3(Ga,Al)5O12:Ce,W and\nGd3(Ga,Al)5O12:Ce,Mo due to a large concentration of various W - and Mo -\nrelated electron traps in these crystals and, consequently, the O- - type hole\ncenters, as well as intrinsic crystal lattice defects (e.g., cation vacancies\nneeded for the excess positive charge compensation of the W6+ and Mo6+ ions).\nThe influence of the co-doping with W and Mo ions on the scintillation\ncharacteristics of Gd3(Ga,Al)5O12:Ce is discussed.",
        "positive": "Direct evidence for minority spin gap in the Co2MnSi Heusler alloy: Half Metal Magnets are of great interest in the field of spintronics because\nof their potential full spin-polarization at the Fermi level and low\nmagnetization damping. The high Curie temperature and predicted 0.7eV minority\nspin gap make the Heusler alloy Co2MnSi very promising for applications.We\ninvestigated the half-metallic magnetic character of this alloy using\nspin-resolved photoemission, ab initio calculation and ferromagnetic resonance.\nAt the surface of Co2MnSi, a gap in the minority spin channel is observed,\nleading to 100% spin polarization. However, this gap is 0.3 eV below the Fermi\nlevel and a minority spin state is observed at the Fermi level. We show that a\nminority spin gap at the Fermi energy can nevertheless be recovered either by\nchanging the stoichiometry of the alloy or by covering the surface by Mn, MnSi\nor MgO. This results in extremely small damping coefficients reaching values as\nlow as 7x 10-4."
    },
    {
        "anchor": "In Situ Thermal Decomposition of Exfoliated Two-Dimensional Black\n  Phosphorus: With a semiconducting band gap and high charge carrier mobility,\ntwo-dimensional (2D) black phosphorus (BP), often referred to as phosphorene,\nholds significant promise for next generation electronics and optoelectronics.\nHowever, as a 2D material, it possesses a higher surface area to volume ratio\nthan bulk BP, suggesting that its chemical and thermal stability will be\nmodified. Herein, an atomic-scale microscopic and spectroscopic study is\nperformed to characterize the thermal degradation of mechanically exfoliated 2D\nBP. From in situ scanning/transmission electron microscopy, decomposition of 2D\nBP is observed to occur at ~400 {\\deg}C in vacuum, in contrast to the 550\n{\\deg}C bulk BP sublimation temperature. This decomposition initiates via\neye-shaped cracks along the [001] direction and then continues until only a\nthin, amorphous red phosphorous like skeleton remains. In situ electron energy\nloss spectroscopy, energy-dispersive X-ray spectroscopy, and energy-loss\nnear-edge structure changes provide quantitative insight into this chemical\ntransformation process.",
        "positive": "Spinel ferrites: old materials bring new opportunities for spintronics: Over the past few years, intensive studies of ultrathin epitaxial films of\nperovskite oxides have often revealed exciting properties like giant\nmagnetoresistive tunnelling and electric field effects. Spinel oxides appear as\neven more versatile due to their more complex structure and the resulting many\ndegrees of freedom. Here we show that the epitaxial growth of nanometric\nNiFe2O4 films onto perovskite substrates allows the stabilization of novel\nferrite phases with properties dramatically differing from bulk ones. Indeed,\nNiFe2O4 films few nanometres thick have a saturation magnetization at least\ntwice that of the bulk compound and their resistivity can be tuned by orders of\nmagnitude, depending on the growth conditions. By integrating such thin NiFe2O4\nlayers into spin-dependent tunnelling heterostructures, we demonstrate that\nthis versatile material can be useful for spintronics, either as a conductive\nelectrode in magnetic tunnel junctions or as a spin-filtering insulating\nbarrier in the little explored type of tunnel junction called spin-filter. Our\nfindings are thus opening the way for the realisation of monolithic spintronics\narchitectures integrating several layers of a single material, where the layers\nare functionalised in a controlled manner."
    },
    {
        "anchor": "Benchmarking vdW-DF first principle predictions against Coupled\n  Electron-Ion Monte Carlo for high pressure liquid hydrogen: We report first principle results for nuclear structure and optical responses\nof high pressure liquid hydrogen along two isotherms in the region of molecular\ndissociation. We employ Density Functional Theory with the vdW-DF approximation\n(vdW) and we benchmark the results against existing predictions from Coupling\nElectron-Ion Monte Carlo (CEIMC). At fixed density and temperature, we find\nthat pressure from vdW is higher than pressure from CEIMC by about 10 GPa in\nthe molecular insulating phase and about 20 GPa in the dissociated metallic\nphase. Molecules are found to be overstabilized using vdW, with a slightly\nshorter bond length, and with a stronger resistance to compression. As a\nconsequence, pressure dissociation along isotherms using vdW is more\nprogressive than computed with CEIMC. Below the critical point, the\nliquid-liquid phase transition is observed with both theories in the same\ndensity region but the one predicted by vdW has a smaller density\ndiscontinuity, i.e. a smaller first order character. The optical conductivity\ncomputed using Kubo-Greenwood is rather similar for the two systems and\nreflects the slightly more pronounced molecular character of vdW.",
        "positive": "Topological Electronic Structure and Its Temperature Evolution in\n  Antiferromagnetic Topological Insulator MnBi2Te4: Topological quantum materials coupled with magnetism can provide a platform\nfor realizing rich exotic physical phenomena, including quantum anomalous Hall\neffect, axion electrodynamics and Majorana fermions. However, these unusual\neffects typically require extreme experimental conditions such as ultralow\ntemperature or sophisticate material growth and fabrication. Recently, new\nintrinsic magnetic topological insulators were proposed in MnBi2Te4-family\ncompounds - on which rich topological effects could be realized under much\nrelaxed experimental conditions. However, despite the exciting progresses, the\ndetailed electronic structures observed in this family of compounds remain\ncontroversial up to date. Here, combining the use of synchrotron and laser\nlight sources, we carried out comprehensive and high resolution angle-resolved\nphotoemission spectroscopy studies on MnBi2Te4, and clearly identified its\ntopological electronic structures including the characteristic gapless\ntopological surface states. In addition, the temperature evolution of the\nenergy bands clearly reveals their interplay with the magnetic phase transition\nby showing interesting differences for the bulk and surface states,\nrespectively. The identification of the detailed electronic structures of\nMnBi2Te4 will not only help understand its exotic properties, but also pave the\nway for the design and realization of novel phenomena and applications."
    },
    {
        "anchor": "Simulation and modeling of the electronic structure of GaAs damage\n  clusters: In an effort to build a stronger microscopic foundation for radiation damage\nmodels in gallium arsenide (GaAs), the electronic properties of\nradiation-induced damage clusters are studied with atomistic simulations.\nMolecular dynamics simulations are used to access the time and length scales\nrequired for direct simulation of a collision cascade, and density functional\ntheory simulations are used to calculate the electronic properties of isolated\ndamaged clusters that are extracted from these cascades. To study the physical\nproperties of clusters, we analyze the statistics of a randomly-generated\nensemble of damage clusters because no single cluster adequately represents\nthis class of defects. The electronic properties of damage clusters are\naccurately described by a classical model of the electrical charging of a\nsemiconducting sphere embedded in an uniform dielectric. The effective band gap\nof the cluster depends on the degree of internal structural damage, and the gap\ncloses to form a metal in the high-damage limit. We estimate the Fermi level of\nthis metallic state, which corresponds to high-energy amorphous GaAs, to be\n0.46 +/- 0.07 eV above the valence band edge of crystalline GaAs.",
        "positive": "A Weakly Coordinating Anion Substantially Enhances Carbon Dioxide\n  Fixation by Calcium and Barium Salts: Carbon dioxide fixation and storage constitute a drastically important\nproblem for the humanity nowadays. We hereby publish a new solution based on\nthe alkaline earth salts with a weakly coordinating anion,\ntetrakis(pentafluorophenyl)borate. The proposed solution was validated using a\nrobust combination of global minimum search and molecular dynamics simulations\nutilizing a well-tested, reliable semiempirical Hamiltonian to monitor chemical\nreactions. Calcium tetrakis(pentafluorophenyl)borate captures 5.5 CO2 molecules\nper mole, whereas barium tetrakis(pentafluorophenyl)borate captures 3.6 CO2\nmolecules per mole. These capacities are much higher, as compared to the\nestablished carbonate technology, which fixes only one CO2 molecule per one\nmetal atom. The conducted simulations reveal that electrostatic binding of CO2\nto alkaline earth cations is more technologically interesting than formation of\ncarbonate salts. Our simulation results can be directly validated by sorption\nmeasurements."
    },
    {
        "anchor": "Topological Landscape of Competing Charge Density Waves in 2H-NbSe2: Despite decades of studies on charge density wave (CDW) of 2H-NbSe2, the\norigin of its incommensurate CDW ground state has not been understood. We\ndiscover that CDW of 2H-NbSe2 is composed of two different, energetically\ncompeting, structures. The lateral heterostructures of two CDWs are entangled\nas topological excitations, which give rise to a CDW phase shift and the\nincommensuration without a conventional domain wall. A partially melt network\nof the topological excitations and their vertices explain an unusual landscape\nof domains. The unconventional topological role of competing phases disclosed\nhere can be widely applied to various incommensuration or phase coexistence\nphenomena in materials.",
        "positive": "Theoretical analysis of magnetic properties and the magnetocaloric\n  effect using the Blume-Capel model: This work investigates the magnetic properties and the magnetocaloric effect\nin the spin-1 Blume-Capel model. The study was carried out using the mean-field\ntheory from the Bogoliubov inequality to obtain the expressions of free energy,\nmagnetization and entropy. The magnetocaloric effect was calculated from the\nvariation of the entropy obtained by the mean-field theory. Due to the\ndependence on the external magnetic field and the anisotropy included in the\nmodel, the results for the magnetocaloric effect provided the system with\nfirst-order and continuous phase transitions. To ensure the results, the\nMaxwell relations were used in the intervals where the model presents\ncontinuous variations in magnetization and the Clausius-Clapeyron equation in\nthe intervals where the model presents discontinuity in the magnetization. The\nmethods and models for the analysis of a magnetic entropy change and\nfirst-order and continuous magnetic phase transitions, such as mean-field\ntheory and the Blume-Capel model, are useful tools in understanding the nature\nof the magnetocaloric effect and its physical relevance."
    },
    {
        "anchor": "Direct Exfoliation of Nanoribbons from Bulk van der Waals Crystals: Confinement of monolayers into quasi-one-dimensional atomically-thin\nnanoribbons could lead to novel quantum phenomena beyond those achieved in\ntheir bulk and monolayer counterparts. However, current experimental\navailability of nanoribbon species beyond graphene has been limited to\nbottom-up synthesis or top-down patterning. In this study, we introduce a\nversatile and direct lithography-free approach to exfoliate a variety of bulk\nvan der Waals (vdW) crystals into nanoribbons. Akin to the Scotch tape\nexfoliation in producing monolayers, this technique provides convenient access\nto a wide range of nanoribbons derived from their corresponding bulk crystals,\nincluding MoS2, WS2, MoSe2, WSe2, MoTe2, WTe2, ReS2, and hBN. The nanoribbons\nare single-crystalline, parallel-aligned, flat, and have high aspect ratio. We\ndemonstrated the electrical, magnetic, and optical properties from the\nconfinement, strain, and edge configurations of these nanoribbons. This\nversatile preparation technique will pave the way for future experimental\ninvestigation and broad applications in optoelectronic, sensing, electronic and\nquantum devices.",
        "positive": "An efficient way to model complex magnetite: assessment of SCC-DFTB\n  against DFT: Magnetite has attracted increasing attention in recent years due to its\npromising and diverse applications in biomedicine. Theoretical modelling can\nplay an important role in understanding magnetite-based nanomaterials at the\natomic scale for a deeper insight into the experimental observations. However,\ncalculations based on density functional theory (DFT) are too costly for\nrealistically large models of magnetite nanoparticles. Classical force field\nmethods are very fast but lack of precision and of the description of\nelectronic effects. Therefore, a cheap and efficient quantum mechanical\nsimulation method with comparable accuracy than DFT is highly desired. Here, a\nless computational demanding DFT-based method, i.e. self-consistent charge\ndensity functional tight-binding (SCC-DFTB), is adopted to investigate\nmagnetite bulk and low-index (001) surface with newly proposed parameters for\nFe-O interactions. We report that SCC-DFTB with on-site Coulomb correction\nprovides results in quantitatively comparable agreement with those obtained by\nDFT+U and hybrid functional methods. Therefore, SCC-DFTB is valued as an\nefficient and reliable method for the description magnetite. This assessment\nwill promote SCC-DFTB computational studies on magnetite-based nanostructures\nthat attract increasing attention for medical applications."
    },
    {
        "anchor": "Enhancing thermoelectric performance of 2D Janus ISbTe by strain\n  engineering: A first principle study: Recent developments in the 2D materials laid emphasis on finding the\nmaterials with robust properties for variety of applications including the\nenergy harvesting. The recent discovery of Janus monolayers with broken\nsymmetry has opened up new options for engineering the properties of 2D layered\nmaterials. Present study focuses on enhancing thermoelectric properties of\n2H-ISbTe 2D Janus monolayer. All the calculations have been performed using\nfully relaxed unit cell and employing the pseudo potential based quantum\nespresso code. Calculated structural parameters are in good agreement with\nprevious literature reports. The lattice dynamics calculations predicts this\nmonolayer can withstand a strain of up to 4% beyond which imaginary frequencies\nappear in the phonon dispersion curves. Computed electronic structure reveals\nthat the monolayer is an indirect wide bandgap material and the bandgap\ndecreases with tensile strain. Furthermore, the computed thermoelectric\nproperties show that the studied monolayer has high Seebeck coefficient of ~\n300 {\\mu}V/K and low thermal conductivity which yields reasonably high ZT of ~\n1.31 for a strain of 2% at 300 K with p-type doping. Therefore, our study\nsignifies the fact that tensile strain and p-type doping of 2D Janus monolayer\nISbTe can enhance ZT from 0.87 to 1.31 at room temperature which makes it a\npromising candidate for thermoelectric applications.",
        "positive": "Micromechanical fatigue experiments for validation of\n  microstructure-sensitive fatigue simulation models: Crack initiation governs high cycle fatigue life and is susceptible to\nmicrostructural details. While corresponding microstructure-sensitive models\nare available, their validation is difficult. We propose a validation framework\nwhere a fatigue test is mimicked in a sub-modeling simulation by embedding the\nmeasured microstructure into the specimen geometry and adopting the\nexperimental boundary conditions. Exemplary, a phenomenological crystal\nplasticity model was applied to predict deformation in ferritic steel\n(EN1.4003). Hotspots in commonly used fatigue indicator parameter maps are\ncompared with damage segmented from micrographs. Along with the data, the\nframework is published for benchmarking future micromechanical fatigue models."
    },
    {
        "anchor": "Orbital-dependent quasiparticle scattering interference in 3R-NbS2: A valley degree of freedom (DOF) in transition metal dichalcogenides with\nbroken inversion symmetry can be controlled through spin and orbital DOFs owing\nto their valley-contrasting characters. Another important aspect of the spin\nand orbital DOFs is that they affect quasiparticle scattering processes that\ngovern the valley lifetime. Here we combine quasiparticle-interference (QPI)\nimaging experiments and theoretical simulations to study the roles of the spin\nand orbital DOFs in 3R-NbS2. We find that the QPI signal arising from an\ninter-valley scattering is noticeably weaker than that caused by an\nintra-valley scattering. We show that this behavior is predominantly associated\nwith the orbital DOF, signifying the different spin and orbital structures of\nspin-split bands at each valley. These findings provide important insights into\nunderstanding the valley-related transport properties.",
        "positive": "Properties of magnetite nanoparticles synthesized through a novel\n  chemical route: We have developed a simple precipitation route to synthesize magnetite\n(Fe3O4) nano-particles with controlled size without any requirement of\ncalcination step at high temperatures. The study of these nano-particles\nindicates an enhancement in saturation magnetization with reduction in size\ndown to ~10 nm beyond which the magnetization reduces. The latter is attributed\nto surface effects becoming predominant as surface to core volume ratio\nincreases. From the view -point of applications, 10 nm size of magnetite\nparticles seems to be the optimum."
    },
    {
        "anchor": "Ultrafast optical observation of spin-pumping induced dynamic exchange\n  coupling in ferromagnetic semiconductor/metal bilayer: Spin angular momentum transfer in magnetic bilayers offers the possibility of\nultrafast and low-loss operation for next-generation spintronic devices. We\nreport the field- and temperature- dependent measurements on the magnetization\nprecessions in Co$_2$FeAl/(Ga,Mn)As by time-resolved magneto-optical Kerr\neffect (TRMOKE). Analysis of the effective Gilbert damping and phase shift\nindicates a clear signature of an enhanced dynamic exchange coupling between\nthe two ferromagnetic (FM) layers due to the reinforced spin pumping at\nresonance. The temperature dependence of the dynamic exchange-coupling reveals\na primary contribution from the ferromagnetism in (Ga,Mn)As.",
        "positive": "Thermal decomposition and chemical vapor deposition: a comparative study\n  of multi-layer growth of graphene on SiC(000-1): This work presents a comparison of the structural, chemical and electronic\nproperties of multi-layer graphene grown on SiC(000-1) by using two different\ngrowth approaches: thermal decomposition and chemical vapor deposition (CVD).\nThe topography of the samples was investigated by using atomic force microscopy\n(AFM), and scanning electron microscopy (SEM) was performed to examine the\nsample on a large scale. Raman spectroscopy was used to assess the\ncrystallinity and electronic behavior of the multi-layer graphene and to\nestimate its thickness in a non-invasive way. While the crystallinity of the\nsamples obtained with the two different approaches is comparable, our results\nindicate that the CVD method allows for a better thickness control of the grown\ngraphene."
    },
    {
        "anchor": "A simple theory of the Invar effect in iron-nickel alloys: Certain alloys of iron and nickel (so-called 'Invar' alloys) exhibit almost\nno thermal expansion over a wide range of temperature. It is clear that this is\nthe result of an anomalous contraction upon heating which counteracts the\nnormal thermal expansion arising from the anharmonicity of lattice vibrations.\nThis anomalous contraction seems to be related to the alloys' magnetic\nproperties, since the effect vanishes at a temperature close to the Curie\ntemperature. However, despite many years of intensive research, a widely\naccepted microscopic theory of the Invar effect in face-centered-cubic Fe-Ni\nalloys is still lacking. Here we present a simple theory of the Invar effect in\nthese alloys based on Ising magnetism, ab initio total energy calculations, and\nthe Debye-Gruneisen model. We show that this theory accurately reproduces\nseveral well known properties of these materials, including Guillaume's famous\nplot1 of the thermal expansion coefficient as a function of the concentration\nof nickel. Within the same framework, we are able to account in a\nstraightforward way for experimentally observed deviations from Vegard's law.\nOur approach supports the idea that the lattice constant is governed by a few\nparameters, including the fraction of iron-iron nearest-neighbour pairs.",
        "positive": "Thickness dependent properties in oxide heterostructures driven by\n  structurally induced metal-oxygen hybridization variations: Thickness driven electronic phase transitions are broadly observed in\ndifferent types of functional perovskite heterostructures. However, uncertainty\nremains whether these effects are solely due to spatial confinement, broken\nsymmetry or rather to a change of structure with varying film thickness. Here,\nwe present direct evidence for the relaxation of oxygen 2p and Mn 3d orbital\n(p-d) hybridization coupled to the layer dependent octahedral tilts within a\nLa2/3Sr1/3MnO3 film driven by interfacial octahedral coupling. An enhanced\nCurie temperature is achieved by reducing the octahedral tilting via interface\nstructure engineering. Atomically resolved lattice, electronic and magnetic\nstructures together with X-ray absorption spectroscopy demonstrate the central\nrole of thickness dependent p-d hybridization in the widely observed\ndimensionality effects present in correlated oxide heterostructures."
    },
    {
        "anchor": "Coupled mass-momenta balance for modeling material failure: Cracks are created by massive breakage of molecular or atomic bonds. The\nlatter, in its turn, leads to the highly localized loss of material, which is\nthe reason why even closed cracks are visible by a naked eye. Thus, fracture\ncan be interpreted as the local material sink. Mass conservation is violated\nlocally in the area of material failure. We consider a theoretical formulation\nof the coupled mass and momenta balance equations for a description of\nfracture. Our focus is on brittle fracture and we propose a finite strain\nhyperelastic thermodynamic framework for the coupled mass-flow-elastic boundary\nvalue problem. The attractiveness of the proposed framework as compared to the\ntraditional continuum damage theories is that no internal parameters (like\ndamage variables, phase fields etc.) are used while the regularization of the\nfailure localization is provided by the physically sound law of mass balance.",
        "positive": "Stochastic model for the 3D microstructure of pristine and cyclically\n  aged cathodes in Li-ion batteries: It is well-known that the microstructure of electrodes in lithium-ion\nbatteries strongly affects their performance. Vice versa, the microstructure\ncan exhibit strong changes during the usage of the battery due to aging\neffects. For a better understanding of these effects, mathematical analysis and\nmodeling has turned out to be of great help. In particular, stochastic 3D\nmicrostructure models have proven to be a powerful and very flexible tool to\ngenerate various kinds of particle-based structures. Recently, such models have\nbeen proposed for the microstructure of anodes in lithium-ion energy and power\ncells. In the present paper, we describe a stochastic modeling approach for the\n3D microstructure of cathodes in a lithium-ion energy cell, which differs\nsignificantly from the one observed in anodes. The model for the cathode data\nenhances the ideas of the anode models, which have been developed so far. It is\ncalibrated using 3D tomographic image data from pristine as well as two aged\ncathodes. A validation based on morphological image characteristics shows that\nthe model is able to realistically describe both, the microstructure of\npristine and aged cathodes. Thus, we conclude that the model is suitable to\ngenerate virtual, but realistic microstructures of lithium-ion cathodes."
    },
    {
        "anchor": "Impact of Oxygen Pressure on Ferroelectric Stability of La-doped Hafnia\n  Grown by PLD: Thin films of HfO2 doped with 4% La were fabricated on LSMO/STO (100)\nsubstrates using pulsed laser deposition. The stability of the ferroelectric\northorhombic phase in the hafnia films was investigated with respect to varying\noxygen pressure during deposition. X-ray diffraction and X-ray photoelectron\nspectroscopy measurements were carried out to analyze the structure and\ncomposition of the films and correlated with their ferroelectric properties.\nSurprisingly, the ferroelectricity of the hafnia films showed a dependence on\noxygen pressure during deposition of LSMO bottom electrode as well. The reason\nfor this dependence is discussed in terms of the active role of non-lattice\noxygen in the ferroelectric switching of hafnia.",
        "positive": "One-step synthesis of van der Waals heterostructures of graphene and 2D\n  superconducting a-Mo2C: Assembling different two-dimensional (2D) crystals, covering a very broad\nrange of properties, into van der Waals (vdW) heterostructures enables the\nunprecedented possibilities for combining the best of different ingredients in\none objective material. So far, metallic, semiconducting, and insulating 2D\ncrystals have been used successfully in making functional vdW heterostructures\nwith properties by design. Here, we expand 2D superconducting crystals as a\nbuilding block of the vdW hererostructures. A one-step growth of large-scale\nhigh-quality vdW heterostructures of graphene and 2D superconducting a-Mo2C by\nusing chemical vapor deposition (CVD) method is reported. The superconductivity\nand its 2D nature of the heterostructures are characterized by our scanning\ntunneling microscopy (STM) measurements. This adds the 2D superconductivity,\nthe most attractive property of condensed matter physics, to the vdW\nheterostructures."
    },
    {
        "anchor": "Insight into the physical properties of two niobium based compounds\n  Nb3Be and Nb3Be2 via first principles calculation: We investigate the structural, electronic, mechanical and elastic properties\nof two niobium based intermetallic compounds Nb3Be and Nb3Be2 by using the DFT\nbased theoretical method. A good agreement is found among the structural\nparameters of both the phases with experimentally evaluated parameters. For\nboth the phases metallic conductivity is observed while Nb3Be phase is more\nconducting than that of Nb3Be2 phase. Evaluated DOS at Fermi level indicates\nthat Nb3Be2 phase is electrically more stable than Nb3Be phase. For both phases\nNb-4d states is mostly responsible for metallic conductivity. The study of\ntotal charge density and Mulliken atomic population reveal the existence of\ncovalent, metallic and ionic bonds in both intermetallics. Both the phases are\nmechanically stable in nature while Nb3Be phase is more ductile than Nb3Be2\nphase. The study of Vickers hardness exhibits that Nb3Be2 phase is harder than\nthat of Nb3Be. Both compounds are anisotropic in nature while Nb3Be phase\npossesses large anisotropic characteristics than that of Nb3Be2 phase. The\nDebye temperature of both the compounds are also calculated and discussed.",
        "positive": "An ab-initio theoretical investigation of the soft-magnetic properties\n  of permalloys: We study Ni80Fe20-based permalloys with the relativistic spin-polarized\nKorringa-Kohn-Rostoker electronic structure method. Treating the compositional\ndisorder with the coherent potential approximation, we investigate how the\nmagnetocrystalline anisotropy, K, and magnetostriction, lambda, of Ni-rich\nNi-Fe alloys vary with the addition of small amounts of non-magnetic transition\nmetals, Cu and Mo. From our calculations we follow the trends in K and lambda\nand find the compositions of Ni-Fe-Cu and Ni-Fe-Mo where both are near zero.\nThese high permeability compositions of Ni-Fe-Cu and Ni-Fe-Mo match well with\nthose discovered experimentally. We monitor the connection of the magnetic\nanisotropy with the number of minority spin electrons, Nmin. By raising Nmin\nvia artificially increasing the band-filling of Ni80Fe20, we are able to\nreproduce the key features that underpin the magnetic softening we find in the\nternary alloys. The effect of band-filling on the dependence of\nmagnetocrystalline anisotropy on atomic short-range order in Ni80Fe20 is also\nstudied. Our calculations, based on a static concentration wave theory,\nindicate that the susceptibility of the high permeability of the Ni-Fe-Cu and\nNi-Fe-Mo alloys to their annealing conditions is also strongly dependent on the\nalloys' compositions. An ideal soft magnet appears from these calculations."
    },
    {
        "anchor": "Growth from Below: Bilayer Graphene on Copper by Chemical Vapor\n  Deposition: We evaluate how a second graphene layer forms and grows on Cu foils during\nchemical vapor deposition (CVD). Low-energy electron diffraction and microscopy\nis used to reveal that the second layer nucleates and grows next to the\nsubstrate, i.e., under a graphene layer. This underlayer mechanism can\nfacilitate the synthesis of uniform single-layer films but presents challenges\nfor growing uniform bilayer films by CVD. We also show that the buried and\noverlying layers have the same edge termination.",
        "positive": "Magnetic Phase Diagram of the Breathing Pyrochlore Antiferromagnet\n  LiGa1-xInxCr4O8: The spinel oxides LiGaCr4O8 and LiInCr4O8 contain size-alternating pyrochlore\nlattices of spin-3/2 Cr3+ tetrahedra with different magnitudes of alternation.\nWe show here that the solid solutions LiGa1-xInxCr4O8 between these two\n'breathing' pyrochlore compounds display (i) rapid suppression of magnetic and\nstructural transitions upon doping the end members, (ii) spin-glass-like\nfreezing above 2 K in the range 0.1 $\\lesssim$ x $\\lesssim$ 0.6, and (iii)\napparent spin-gap behavior for x $\\gtrsim$ 0.7. Furthermore, no transitions are\nobserved above 2 K at x ~ 0.9, where magnetic susceptibility remains finite at\n2 K and magnetic heat capacity shows a quadratic temperature dependence at 1-5\nK. Our work shows that breathing pyrochlore compounds provide a unique\nopportunity for studying both geometrical frustration and bond alternation."
    },
    {
        "anchor": "Effects of domain walls in bilayer graphene in an external magnetic\n  field: We investigate bilayer graphene systems with layer switching domain walls\nseparating the two energetically equivalent Bernal stackings in the presence of\nan external magnetic field. To this end we calculate quantum transport and\nlocal densities of three microscopic models for a single domain wall: a hard\nwall, a defect due to shear, and a defect due to tension. The quantum transport\ncalculations are performed with a recursive Green's function method.\nTechnically, we discuss an explicit algorithm for the separation of a system\ninto subsystems for the recursion and we present an optimization of the well\nknown iteration scheme for lead self-energies for sparse chain couplings. We\nfind strong physical differences for the three different types of domain walls\nin the integer quantum Hall regime. For a domain wall due to shearing of the\nupper graphene layer there is a plateau formation in the magnetoconductance for\nsufficiently wide defect regions. For wide domain walls due to tension in the\nupper graphene layer there is only an approximate plateau formation with\nfluctuations of the order of the elementary conuctance quantum $\\sigma_0$. A\ndirect transition between stacking regions like for the hard wall domain wall\nshows no plateau formation and is therefore not a good model for either of the\npreviously mentioned extended domain walls.",
        "positive": "Structural and magnetic properties of GdCo$_{5-x}$Ni$_x$: GdCo$_5$ may be considered as two sublattices - one of Gd and one of Co -\nwhose magnetizations are in antiparallel alignment, forming a ferrimagnet.\nSubstitution of nickel in the cobalt sublattice of GdCo$_5$ has been\ninvestigated to gain insight into how the magnetic properties of this prototype\nrare-earth/transition-metal magnet are affected by changes in the transition\nmetal sublattice. Polycrystalline samples of GdCo$_{5-x}$Ni$_x$ for 0 $ \\leq x\n\\leq $ 5 were synthesized by arc melting. Structural characterization was\ncarried out by powder x-ray diffraction and optical and scanning electron\nmicroscope imaging of metallographic slides, the latter revealing a low\nconcentration of Gd$_2$(Co, Ni)$_7$ lamellae for $x \\leq 2.5$. Compensation -\ni.e. the cancellation of the opposing Gd and transition metal moments is\nobserved for $1 \\leq x \\leq 3$ at a temperature which increases with Ni\ncontent; for larger $x$, no compensation is observed below 360 K. A peak in the\ncoercivity is seen at $x \\approx 1$ at 10K coinciding with a minimum in the\nsaturation magnetization. Density-functional theory calculations within the\ndisordered local moment picture reproduce the dependence of the magnetization\non Ni content and temperature. The calculations also show a peak in the\nmagnetocrystalline anisotropy at similar Ni concentrations to the\nexperimentally observed coercivity maximum."
    },
    {
        "anchor": "Tetracene ultrathin film growth on silicon: Inorganic-organic interfaces are important for enhancing the power conversion\nefficiency of silicon-based solar cells through singlet exciton fission (SF).\nWe elucidated the structure of the first monolayers of tetracene (Tc), a SF\nmolecule, on hydrogen-passivated Si(111) [H-Si(111)] and hydrogenated amorphous\nSi (a-Si:H) by combining near-edge X-ray absorption fine structure (NEXAFS) and\nX-ray photoelectron spectroscopy (XPS) experiments with density functional\ntheory (DFT) calculations. For samples grown at or below substrate temperatures\nof 265 K, the resulting ultrathin Tc films are dominated by almost\nupright-standing molecules. The molecular arrangement is very similar to the Tc\nbulk phase, with only slightly higher average angle between the conjugated\nmolecular plane normal and the surface normal ($\\alpha$) around 77{\\deg}.\nJudging from carbon K-edge X-ray absorption spectra, the orientation of the Tc\nmolecules are almost identical when grown on H-Si(111) and a-Si:H substrates as\nwell as for (sub)mono- to several-monolayer coverages. Annealing to room\ntemperature, however, changes the film structure towards a smaller $\\alpha$ of\nabout 63{\\deg}. A detailed DFT-assisted analysis suggests that this structural\ntransition is correlated with a lower packing density and requires a\nwell-chosen amount of thermal energy. Therefore, we attribute the resulting\nstructure to a distinct monolayer configuration that features less inclined,\nbut still well-ordered molecules. The larger overlap with the substrate\nwavefunctions makes this arrangement attractive for an optimized interfacial\nelectron transfer in SF-assisted silicon solar cells.",
        "positive": "Highly Quantum-Confined InAs Nanoscale Membranes: Nanoscale size-effects drastically alter the fundamental properties of\nsemiconductors. Here, we investigate the dominant role of quantum confinement\nin the field-effect device properties of free-standing InAs nanomembranes with\nvaried thicknesses of 5-50 nm. First, optical absorption studies are performed\nby transferring InAs \"quantum membranes\" (QMs) onto transparent substrates,\nfrom which the quantized sub-bands are directly visualized. These sub-bands\ndetermine the contact resistance of the system with the experimental values\nconsistent with the expected number of quantum transport modes available for a\ngiven thickness. Finally, the effective electron mobility of InAs QMs is shown\nto exhibit anomalous field- and thickness-dependences that are in distinct\ncontrast to the conventional MOSFET models, arising from the strong quantum\nconfinement of carriers. The results provide an important advance towards\nestablishing the fundamental device physics of 2-D semiconductors."
    },
    {
        "anchor": "Solid molecular hydrogen: The Broken Symmetry Phase: By performing constant-pressure variable-cell ab initio molecular dynamics\nsimulations we find a quadrupolar orthorhombic structure, of $Pca2_1$ symmetry,\nfor the broken symmetry phase (phase II) of solid H2 at T=0 and P =110 - 150\nGPa. We present results for the equation of state, lattice parameters and\nvibronic frequencies, in very good agreement with experimental observations.\nAnharmonic quantum corrections to the vibrational frequencies are estimated\nusing available data on H2 and D2. We assign the observed modes to specific\nsymmetry representations.",
        "positive": "Two-dimensional honeycomb borophene oxide: A promising anode material\n  offering super high capacity for Li/Na-ion batteries: Rational design of novel two-dimensional (2D) electrode materials with high\ncapacity is crucial for the further development of Li-ion and Na-ion batteries.\nHerein, based on first-principles calculations, we systemically investigate Li\nand Na storage behaviors in the recently discovered 2D topological nodal-loop\nmetal - the honeycomb borophene oxide (h-B2O). We show that h-B2O is an almost\nideal anode material. It has good conductivity before and after Li/Na\nadsorption, fast ion diffusion with diffusion barrier less than 0.5 eV, low\nopen-circuit voltage (less than 1 V), and small lattice change (less than 6.2%)\nduring intercalation. Most remarkably, its theoretical storage capacity is\nextremely high, reaching up to 2137 mAh/g for Li and 1425 mAh/g for Na. Its Li\nstorage capacity is more than six times higher than graphite (372 mAh/g), and\nis actually the highest among all 2D materials discovered to date. Our results\nstrongly suggest that 2D h-B2O is an exceedingly promising anode material for\nboth Li- and Na-ion batteries with super high capacity."
    },
    {
        "anchor": "From multiferroics to cosmology: Scaling behaviour and beyond in the\n  hexagonal manganites: We show that the improper ferroelectric phase transition in the multiferroic\nhexagonal manganites displays the same symmetry-breaking characteristics as\nthose proposed in early-universe theories. We present an analysis of the\nKibble-Zurek theory of topological defect formation applied to the hexagonal\nmanganites, discuss the conditions determining the range of cooling rates in\nwhich Kibble-Zurek behavior is expected, and show that recent literature data\nare consistent with our predictions. We explore experimentally for the first\ntime to our knowledge the cross-over out of the Kibble-Zurek regime and find a\nsurprising \"anti-Kibble-Zurek\" behavior.",
        "positive": "Interlayer shear strength of single crystalline graphite: Reported values (0.2 MPa ~ 7.0 GPa) of the interlayer shear strength (ISS) of\ngraphite are very dispersed. The main challenge to obtain a reliable value of\nISS is the lack of precise experimental methods. Here we present a novel\nexperimental approach to measure the ISS, and obtain the value as 0.14 GPa. Our\nresult can serve as an important basis for understanding mechanical behavior of\ngraphite or graphene-based materials."
    },
    {
        "anchor": "An ab initio study of intrinsic defects in zirconolite: Zirconolite, CaZrTi2O7, is a proposed ceramic for the use in disposal of\nhighly active nuclear waste. Density functional theory (DFT) has been used, in\nconjunction with a random search technique, to identify the stable interstitial\nsites for the intrinsic defects in zirconolite. There is a significant\ndependence on charge states for the vacancy defect structures, with the\nformation of an O2 molecule in certain charge states of Ti and Zr vacancies.\nThe low coordination of the oxygen ions provided sites on which DFT localised\nholes associated with the cation vacancies. The Frenkel defect energies,\ncalculated from the combination of the vacancy and interstitial formation\nenergies, show that the oxygen defects have a strong dependence on the chemical\nenvironment, with a range of 1.5 eV between the oxygen Frenkel pair energies.",
        "positive": "Spin-Polarized Quantum Well States on Bi$_{2-x}$Fe$_x$Se$_3$: Low temperature scanning tunneling microscopy is used to image the doped\ntopological insulator Bi$_{2-x}$Fe$_x$Se$_3$. Interstitial Fe defects allow the\ndetection of quasiparticle interference (QPI), and the reconstruction of the\nempty state band structure. Quantitative comparison between measured data and\ndensity functional theory calculations reveals the unexpected coexistence of\nquantum well states (QWS) with topological surface states (TSS) on the\natomically clean surface of Bi$_{2-x}$Fe$_x$Se$_3$. Spectroscopic measurements\nquantify the breakdown of linear dispersion due to hexagonal warping.\nNonetheless, both QWS and TSS remain spin-polarized and protected from\nbackscattering to almost 1 eV above the Dirac point, suggesting their utility\nfor spin-based applications."
    },
    {
        "anchor": "Semiconducting character of LaN: magnitude of the band gap, and origin\n  of the electrical conductivity: Lanthanum nitride (LaN) has attracted research interest in catalysis due to\nits ability to activate the triple bonds of N$_2$ molecules, enabling efficient\nand cost-effective synthesis of ammonia from N$_2$ gas. While exciting progress\nhas been made to use LaN in functional applications, the electronic character\nof LaN (metallic, semi-metallic, or semiconducting) and magnitude of its band\ngap have so far not been conclusively determined. Here, we investigate the\nelectronic properties of LaN with hybrid density functional theory\ncalculations. In contrast to previous claims that LaN is semi-metallic, our\ncalculations show that LaN is a direct-band-gap semiconductor with a band-gap\nvalue of 0.62 eV at the X point of the Brillouin zone. The dispersive character\nof the bands near the band edges leads to light electron and hole effective\nmasses, making LaN promising for electronic and optoelectronic applications.\nOur calculations also reveal that nitrogen vacancies and substitutional oxygen\natoms are two unintentional shallow donors with low formation energies that can\nexplain the origin of the previously reported electrical conductivity. Our\ncalculations clarify the semiconducting nature of LaN and reveal candidate\nunintentional point defects that are likely responsible for its measured\nelectrical conductivity.",
        "positive": "The vibrational properties of benzene on an ordered water ice surface: We present a hybrid CCSD(T)+PBE-D3 approach to calculating the vibrational\nsignatures for gas phase benzene and benzene adsorbed on an ordered water-ice\nsurface. We compare the results of our method against experimentally recorded\nspectra and calculations performed using PBE-D3-only approaches (harmonic and\nanharmonic). Calculations use a proton ordered XIh water-ice surface consisting\nof 288 water molecules, and results are compared against experimental spectra\nrecorded for an ASW ice surface. We show the importance of including a water\nice surface into spectroscopic calculations, owing to the resulting differences\nin vibrational modes, frequencies and intensities of transitions seen in the IR\nspectrum. The overall intensity pattern shifts from a dominating $\\nu_{11}$\nband in the gas-phase to several high-intensity carriers for an IR spectrum of\nadsorbed benzene. When used for adsorbed benzene, the hybrid approach presented\nhere achieves an RMSD for IR active modes of 21~cm$^{-1}$, compared to\n72~cm$^{-1}$ and 49~cm$^{-1}$ for the anharmonic and harmonic PBE-D3\napproaches, respectively. Our hybrid model for gaseous benzene also achieves\nthe best results when compared to experiment, with an RMSD for IR active modes\nof 24~cm$^{-1}$, compared to 55~cm$^{-1}$ and 31~cm$^{-1}$ for the anharmonic\nand harmonic PBE-D3 approaches, respectively. To facilitate assignment, we\ngenerate and provide a correspondence graph between the normal modes of the\ngaseous and adsorbed benzene molecules. Finally, we calculate the frequency\nshifts, $\\Delta\\nu$, of adsorbed benzene relative to its gas phase to highlight\nthe effects of surface interactions on vibrational bands and evaluate the\nsuitability of our chosen dispersion-corrected density functional theory."
    },
    {
        "anchor": "The rule of four: anomalous stoichiometries of inorganic compounds: Why are materials with specific characteristics more abundant than others?\nThis is a fundamental question in materials science and one that is\ntraditionally difficult to tackle, given the vastness of compositional and\nconfigurational space. We highlight here the anomalous abundance of inorganic\ncompounds whose primitive unit cell contains a number of atoms that is a\nmultiple of four. This occurrence - named here the 'rule of four' - has to our\nknowledge not previously been reported or studied. Here, we first highlight the\nrule's existence, especially notable when restricting oneself to experimentally\nknown compounds, and explore its possible relationship with established\ndescriptors of crystal structures, from symmetries to energies. We then\ninvestigate this relative abundance by looking at structural descriptors, both\nof global (packing configurations) and local (the smooth overlap of atomic\npositions) nature. Contrary to intuition, the overabundance does not correlate\nwith low-energy or high-symmetry structures; in fact, structures which obey the\n'rule of four' are characterized by low symmetries and loosely packed\narrangements maximizing the free volume. We are able to correlate this\nabundance with local structural symmetries, and visualize the results using a\nhybrid supervised-unsupervised machine learning method.",
        "positive": "Relations between structural distortions and transport properties in\n  Nd$_{0.5}$Ca$_{0.5}$MnO$_3$ strained thin films: Strained thin films of charge/orbital ordered (CO/OO) $Nd_{0.5}Ca_{0.5}MnO_3$\n(NCMO) with various thickness have grown on (100)-SrTiO$_3$ and (100)-LaAlO$_3$\nsubstrates, by using the Pulsed Laser Deposition (PLD) technique. The thickness\nof the films influences drastically the transport properties. As the thickness\ndecreases, the CO transition increases while at the same time the\ninsulator-to-metal transition temperature decreases under application of a 7T\nmagnetic field. Clear relationships between the structural distortions and the\ntransport properties are established. They are explained on the basis of the\nelongation and the compression of the Mn-O-Mn and Mn-O bond angles and\ndistances of the \\QTR{it}{Pnma} structure, which modify the bandwidth and the\nJahn-Teller distortion in these materials"
    },
    {
        "anchor": "Spintronic and electrochromic device based on Li-intercalated\n  transition-metal doped anatase $\\rm TiO_2$: We have explored the effects of the Li intercalation on the electronic and\nmagnetic properties of transition-metal (TM) doped anatase TiO$_2$. By Li\nintercalation, Mn-doped TiO$_2$ exhibits the insulator to metal transition. On\nthe other hand, Li-intercalated Fe-doped TiO$_2$ has the insulating ground\nstate for low concentration of Li/Ti=0.067, but the metallic ground state for\nhigh concentration of Li/Ti=0.133. We discuss the $n$-type carrier induced\nferromagnetism in Li-intercalated TM-doped anatase TiO$_2$. Based on the\nLi-intercalated TM-doped anatase TiO$_2$, we propose a potential spintronic and\nelectrochromic device controlled by the electric-field.",
        "positive": "Non-destructive determination of phase, size, and strain of individual\n  grains in polycrystalline photovoltaic materials: We demonstrate a non-destructive approach to provide structural properties on\nthe grain level for the absorber layer of kesterite solar cells. Kesterite\nsolar cells are notoriously difficult to characterize structurally due to the\nco-existence of several phases with very similar lattice parameters.\nSpecifically, we present a comprehensive study of 597 grains in the absorber\nlayer of a 1.64% efficient Cu2ZnSnS4 (CZTS) thin-film solar cell, from which 15\ngrains correspond to the secondary phase ZnS. By means of three dimensional\nX-ray diffraction (3DXRD), we obtained statistics for the phase, size,\norientation, and strain tensors of the grains, as well as their twin relations.\nWe observe an average tensile stress in the plane of the film of ~ 70 MPa and a\ncompressive stress along the normal to the film of ~ 145 MPa. At the grain\nlevel, we derive a 3D stress tensor that deviates from the biaxial model\nusually assumed for thin films. 41% of the grains are twins. We calculate the\nfrequency of the six types of $\\Sigma$3 boundaries, revealing that 180{\\deg}\nrotations along axis <221> is the most frequent. This technique can be applied\nto polycrystalline thin film solar cells in general, where strain can influence\nthe bandgap of the absorber layer material, and twin boundaries play a role in\nthe charge transport mechanisms."
    },
    {
        "anchor": "A Solid-State Dielectric Elastomer Switch for Soft Logic: In this paper we describe a stretchable solid-state electronic switching\nmaterial that operates at high voltage potentials, as well as a switch material\nbenchmarking technique that utilizes a modular dielectric elastomer (artificial\nmuscle) ring oscillator. The solid-state switching material was integrated into\nour oscillator, which self-started after 16s and performed 5 oscillations at a\nfrequency of 1.05Hz with 3.25kV DC input. Our materials-by-design approach for\nthe nickel filled polydimethysiloxane (Ni-PDMS) based switch has resulted in\nsignificant improvements over previous carbon-grease based switches in four key\nareas, namely sharpness of switching behavior upon applied stretch, magnitude\nof electrical resistance change, ease of manufacture, and rate of production.\nSwitch lifetime was demonstrated to be in the range of tens to hundreds of\ncycles with the current process. An interesting and potentially useful\nstrain-based switching hysteresis behavior is also presented.",
        "positive": "Ultrafast spin-lattice relaxation in ferromagnets including effective\n  spin-orbit fields: We investigate ultrafast demagnetization due to electron-phonon interaction\nin a model band-ferromagnet. We show that the microscopic mechanism behind the\nspin dynamics due to electron-phonon interaction is the interplay of scattering\nand the precession around momentum-dependent effective internal spin-orbit\nmagnetic fields. The resulting magnetization dynamics can only be mimicked by\nspin-flip transitions if the spin precession around the internal fields is\nsufficiently fast (compared to the scattering time) so that it averages out the\ntransverse spin components."
    },
    {
        "anchor": "Can Copper Nanostructures Sustain High-Quality Plasmons?: Silver is considered to be the king among plasmonic materials because it\nfeatures low inelastic absorption in the visible and infrared (vis-IR) spectral\nregions compared to other metals. In contrast, copper is commonly regarded as\nbeing too lossy for plasmonic applications. Here, we experimentally demonstrate\nvis-IR plasmons in long copper nanowires (NWs) with quality factors that exceed\na value of 60, as determined by spatially resolved, high-resolution electron\nenergy-loss spectroscopy (EELS) measurements. We explain this counterintuitive\nresult by the fact that plasmons in these metal wires have most of their\nelectromagnetic energy outside the metal, and thus, they are less sensitive to\ninelastic losses in the material. We present an extensive set of data acquired\non long silver and copper NWs of varying diameters supporting this conclusion\nand further allowing us to understand the relative roles played by radiative\nand nonradiative losses in plasmons that span a wide range of energies down to\n$<20\\,$meV. At such small plasmon energies, thermal population of these modes\nbecomes significant enough to enable the observation of electron energy gains\nassociated with plasmon absorption events. Our results support the use of\ncopper as an attractive cheap and abundant material platform for high quality\nplasmons in elongated nanostructures.",
        "positive": "Reversible modulation of orbital occupations via an interface-induced\n  state in metallic manganites: The breaking of orbital degeneracy on a transition metal cation and the\nresulting unequal electronic occupations of these orbitals provide a powerful\nlever over electron density and spin ordering inmetal oxides. Here, we use ab\ninitio calculations to show that reversibly modulating the orbital populations\non Mn atoms can be achieved at ferroelectric/manganite interfaces by the\npresence of ferroelectric polarization on the nanoscale. The change in orbital\noccupation can be as large as 10%, greatly exceeding that of bulk manganites.\nThis reversible orbital splitting is in large part controlled by the\npropagation of ferroelectric polar displacements into the interfacial region, a\nstructural motif absent in the bulk and unique to the interface. We use\nepitaxial thin film growth and scanning transmission electron microscopy to\nverify this key interfacial polar distortion and discuss the potential of\nreversible control of orbital polarization via nanoscale ferroelectrics."
    },
    {
        "anchor": "Influence of resonant tunneling on the imaging of atomic defects on\n  InAs(110) surfaces by low-temperature scanning tunneling microscopy: We have used a low-temperature scanning tunneling microscope (STM) to study\nthe surface of heavily doped semiconductor InAs crystals. The crystals are\ncleaved in situ along the (110) plane. Apart from atomically flat areas, we\nalso observe two major types of atomic scale defects which can be identified as\nS dopant atoms and as As vacancies, respectively. The strong bias voltage\ndependence of the STM image of the impurities can be explained in terms of\nresonant tunneling through localized states which are present near the\nimpurity.",
        "positive": "Effects of Antiferromagnetic Spin Rotation on Anisotropy of\n  Ferromagnetic/Antiferromagnetic Bilayers: In epitaxial (111) oriented Ni$_{80}$Fe$_{20}$/Fe$_{50}$Mn$_{50}$ bilayers,\nwe separate two distinct behaviors: unidirectional anisotropy (exchange bias)\nin thick Fe$_{50}$Mn$_{50}$, and enhanced coercivity in thin\nFe$_{50}$Mn$_{50}$. By measuring the magnetization response to a rotating\nmagnetic field, we quantitatively determine the relevant anisotropies, and\ndemonstrate that the enhanced coercivity is related to the rotatable magnetic\nanisotropy of Fe$_{50}$Mn$_{50}$. We also demonstrate the consequences of the\nanisotropy changes with temperature."
    },
    {
        "anchor": "How strong is the Second Harmonic Generation in single-layer\n  monochalcogenides? A response from first-principles real-time simulations: Second Harmonic Generation (SHG) of single-layer monochalcogenides, such as\nGaSe and InSe, has been recently reported [2D Mater. 5 (2018) 025019; J. Am.\nChem. Soc. 2015, 137, 79947997] to be extremely strong with respect to bulk and\nmultilayer forms. To clarify the origin of this strong SHG signal, we perform\nfirst-principles real-time simulations of linear and non-linear optical\nproperties of these two-dimensional semiconducting materials. The simulations,\nbased on ab-initio many-body theory, accurately treat the electron-hole\ncorrelation and capture excitonic effects that are deemed important to\ncorrectly predict the optical properties of such systems. We find indeed that,\nas observed for other 2D systems, the SHG intensity is redistributed at\nexcitonic resonances. The obtained theoretical SHG intensity is an order of\nmagnitude smaller than that reported at the experimental level. This result is\nin substantial agreement with previously published simulations which neglected\nthe electron-hole correlation, demonstrating that many-body interactions are\nnot at the origin of the strong SHG measured. We then show that the\nexperimental data can be reconciled with the theoretical prediction when a\nsingle layer model, rather than a bulk one, is used to extract the SHG\ncoefficient from the experimental data.",
        "positive": "d0 Ferromagnetic Interface Between Non-magnetic Perovskites: We use computational and experimental methods to study d0 ferromagnetism at a\ncharge- imbalanced interface between two perovskites. In SrTiO3/KTaO3\nsuperlattice calculations, the charge imbalance introduces holes in the SrTiO3\nlayer, inducing a d0 ferromagnetic half-metallic 2D electron gas at the\ninterface oxygen 2p orbitals. The charge imbalance overrides doping by\nvacancies at realistic concentrations. Varying the constituent materials shows\nferromagnetism to be a gen- eral property of hole-type d0 perovskite\ninterfaces. Atomically sharp epitaxial d0 SrTiO3/KTaO3, SrTiO3 /KNbO3 and\nSrTiO3 /NaNbO3 interfaces are found to exhibit ferromagnetic hysteresis at room\ntemperature. We suggest the behavior is due to high density of states and\nexchange coupling at the oxygen t1g band in comparison with the more studied d\nband t2g symmetry electron gas."
    },
    {
        "anchor": "Designing magnetism in Fe-based Heusler alloys: a machine learning\n  approach: Combining material informatics and high-throughput electronic structure\ncalculations offers the possibility of a rapid characterization of complex\nmagnetic materials. Here we demonstrate that datasets of electronic properties\ncalculated at the ab initio level can be effectively used to identify and\nunderstand physical trends in magnetic materials, thus opening new avenues for\naccelerated materials discovery. Following a data-centric approach, we utilize\na database of Heusler alloys calculated at the density functional theory level\nto identify the ideal ions neighbouring Fe in the $X_2$Fe$Z$ Heusler prototype.\nThe hybridization of Fe with the nearest neighbour $X$ ion is found to cause\nredistribution of the on-site Fe charge and a net increase of its magnetic\nmoment proportional to the valence of $X$. Thus, late transition metals are\nideal Fe neighbours for producing high-moment Fe-based Heusler magnets. At the\nsame time a thermodynamic stability analysis is found to restrict $Z$ to main\ngroup elements. Machine learning regressors, trained to predict magnetic moment\nand volume of Heusler alloys, are used to determine the magnetization for all\nmaterials belonging to the proposed prototype. We find that Co$_2$Fe$Z$ alloys,\nand in particular Co$_2$FeSi, maximize the magnetization, which reaches values\nup to 1.2T. This is in good agreement with both ab initio and experimental\ndata. Furthermore, we identify the Cu$_2$Fe$Z$ family to be a cost-effective\nmaterials class, offering a magnetization of approximately 0.65T.",
        "positive": "Microstructural constitutive model for polycrystal viscoplasticity in\n  cold and warm regimes based on continuum dislocation dynamics: Viscoplastic flow of polycrystalline metallic materials is the result of\nmotion and interaction of dislocations, line defects of the crystalline\nstructure. In the microstructural (physics-based) constitutive model presented\nin this paper, the main underlying microstructural processes influencing\nviscoplastic deformation and mechanical properties of metals in cold and warm\nregimes are statistically described by the introduced sets of postulates/axioms\nfor continuum dislocation dynamics (CDD). Three microstructural (internal)\nstate variables (MSVs) are used for statistical quantifications of different\ntypes/species of dislocations by the notion of dislocation density. Considering\nthe mobility property of dislocations, they are categorized to mobile and\n(relatively) immobile dislocations. Mobile dislocations carry the plastic\nstrain (rate), while immobile dislocations contribute to plastic hardening.\nMoreover, with respect to their arrangement, dislocations are classified to\ncell and wall dislocations. Cell dislocations are those that exist inside\ncells/subgrains, and wall dislocations are packed in (and consequently formed)\nthe subgrain walls/boundaries. Therefore, the MSVs incorporated in this model\nare cell mobile, cell immobile and wall immobile dislocation densities. The\nevolution of these internal variables is calculated by means of adequate\nequations that characterize the dislocation processes dominating material\nbehavior during cold and warm monotonic viscoplastic deformation. The\nconstitutive equations are then numerically integrated; and the constitutive\nparameters are determined/fitted for a widely used ferritic-pearlitic steel\n(20MnCr5)."
    },
    {
        "anchor": "Accelerated screening of thermoelectric materials by first-principles\n  computations of electron-phonon scattering: Recent discovery of new materials for thermoelectric energy conversion is\nenabled by efficient prediction of materials' performance from\nfirst-principles, without empirically fitted parameters. The novel simplified\napproach for computing electronic transport properties is described, which\nachieves good accuracy and transferability while greatly reducing complexity\nand computation cost compared to the existing methods. The first-principles\ncalculations of the electron-phonon coupling demonstrate that the energy\ndependence of the electron relaxation time varies significantly with chemical\ncomposition and carrier concentration, suggesting that it is necessary to go\nbeyond the commonly used approximations to screen and optimize materials'\ncomposition, carrier concentration, and microstructure. The new method is\nverified using high accuracy computations and validated with experimental data\nbefore applying it to screen and discover promising compositions in the space\nof half-Heusler alloys. By analyzing data trends the effective electron mass is\nidentified as the single best general descriptor determining material's\nperformance. The Lorenz number is computed from first principles and the\nuniversality of the Wiedemann-Franz law in thermoelectrics is discussed.",
        "positive": "Algorithm to compute the electric field gradient tensor in ionic\n  crystals: A simple algorithm and a computational program to numerically compute the\nelectric field gradient and the concomitant quadrupolar nuclear splitting is\ndeveloped for an arbitrary ionic crystal. The calculations are performed using\na point charge model. The program provides three different ways for the data\ninput: by Bravais lattices, by lattice parameters, or by introducing any\nspatial structure. The program calculates the components of the electric field\ngradient, the asymmetry parameter and the quadrupolar splitting for a given\nnumber of nearest neighbors with respect to the nuclear charge as origin. In\naddition, the program allows the use of different Sternheimer antishielding\nfactors."
    },
    {
        "anchor": "Optimal design and quantum limit for second harmonic generation in\n  semiconductor heterostructures: The optimal design for infrared second harmonic generation (SHG) is\ndetermined for a GaAs-based quantum device using a recently developed genetic\napproach. Both compositional parameters and electric field are simultaneously\noptimized, and the quantum limit for SHG, set by the trade-off between large\ndipole moments (favouring electron delocalization) and large overlaps\n(favouring electron localization), is determined. Optimal devices are generally\nobtained with an asymmetric double quantum well shape with narrow barriers and\na graded region sideways to the largest well. An electric field is not found to\nlead to improved SHG if compositional parameters are optimized.",
        "positive": "Atomistic mechanism of graphene growth on SiC substrate: Large-scale\n  molecular dynamics simulation based on a new charge-transfer bond-order type\n  potential: Thermal decomposition of silicon carbide is a promising approach for the\nfabrication of graphene. However, the atomistic growth mechanism of graphene\nremains unclear. This paper describes the development of a new charge-transfer\ninteratomic potential. Carbon bonds with a wide variety of characteristics can\nbe reproduced by the proposed vectorized bond-order term. Large-scale thermal\ndecomposition simulation enables us to observe the continuous growth process of\nthe multi-ring carbon structure. The annealing simulation reveals the atomistic\nprocess by which the multi-ring carbon structure is transformed to flat\ngraphene involving only 6-membered rings. Also, it is found that the surface\natoms of the silicon carbide substrate enhance the homogeneous graphene\nformation."
    },
    {
        "anchor": "Two-dimensional Ga$_2$O$_3$ glass: a large scale passivation and\n  protection material for monolayer WS$_2$: Atomically thin transition metal dichalcogenide crystals (TMDCs) have\nextraordinary optical properties that make them attractive for future\noptoelectronic applications. Integration of TMDCs into practical all-dielectric\nheterostructures hinges on the ability to passivate and protect them against\nnecessary fabrication steps on large scales. Despite its limited scalability,\nencapsulation of TMDCs in hexagonal boron nitride (hBN) currently has no viable\nalternative for achieving high performance of the final device. Here, we show\nthat the novel, ultrathin Ga$_2$O$_3$ glass is an ideal centimeter-scale\ncoating material that enhances optical performance of the monolayers and\nprotects them against further material deposition. In particular, Ga$_2$O$_3$\ncapping of commercial grade WS$_2$ monolayers outperforms hBN in both\nscalability and optical performance at room temperature. These properties make\nGa$_2$O$_3$ highly suitable for large scale passivation and protection of\nmonolayer TMDCs in functional heterostructures.",
        "positive": "Strongly spin-orbit coupled two-dimensional electron gas emerging near\n  the surface of polar semiconductors: We investigate the two-dimensional (2D) highly spin-polarized electron\naccumulation layers commonly appearing near the surface of n-type polar\nsemiconductors BiTeX (X = I, Br, and Cl) by angular-resolved photoemission\nspectroscopy. Due to the polarity and the strong spin-orbit interaction built\nin the bulk atomic configurations, the quantized conduction-band subbands show\ngiant Rashba-type spin-splitting. The characteristic 2D confinement effect is\nclearly observed also in the valence-bands down to the binding energy of 4 eV.\nThe X-dependent Rashba spin-orbit coupling is directly estimated from the\nobserved spin-split subbands, which roughly scales with the inverse of the\nband-gap size in BiTeX."
    },
    {
        "anchor": "Size effect on deformation twinning at the nanoscale in hcp metals: Deformation twinning is generally considered to be the primary mechanism for\nhexagonal close-packed (hcp) metals due to their limited slip systems. Recent\nmicrocompression experiments on hcp metals point to intriguing strong size\neffects on twinning mechanisms, indicating that pyramidal slips dominate\ncompression.In this work we analyze size effects on twinning due to\nlattice-rotation strain in hcp single crystals. A criterion for deformation\ntwinning is derived at the nanoscale and tested by molecular dynamics\nsimulations of magnesium and titanium single crystals. The results show <c+a>\npyramidal slip dominates the compression deformation at the nanoscale,\nconsistent with experimental observations as well as our analysis. Our finding\nclarifies the nature of size effects in deformation twinning, while also\nproviding an explanation for the so-called strength differential (SD) effect.",
        "positive": "First principles-based calculation of the electrocaloric effect in\n  BaTiO$_3$: comparison between direct and indirect methods: We use molecular dynamics simulations for a first principles-based effective\nHamiltonian to calculate two important quantities characterizing the\nelectrocaloric effect in BaTiO$_3$, the adiabatic temperature change $\\Delta T$\nand the isothermal entropy change $\\Delta S$, for different electric field\nstrengths. We compare direct and indirect methods to obtain $\\Delta T$ and\n$\\Delta S$, and we confirm that both methods indeed lead to identical result\nprovided that the system does not actually undergo a first order phase\ntransition. We also show that a large electrocaloric response is obtained for\nelectric fields beyond the critical field strength for the first order phase\ntransition. Furthermore, our work fills several gaps regarding the application\nof the first principles-based effective Hamiltonian approach, which represents\na very attractive and powerful method for the quantitative prediction of\nelectrocaloric properties. In particular, we discuss the importance of\nmaintaining thermal equilibrium during the field ramping when calculating\n$\\Delta T$ using the direct method within a molecular dynamics approach."
    },
    {
        "anchor": "Layer Hall effect in a 2D topological Axion antiferromagnet: While ferromagnets have been known and exploited for millennia,\nantiferromagnets (AFMs) were only discovered in the 1930s. The elusive nature\nindicates AFMs' unique properties: At large scale, due to the absence of global\nmagnetization, AFMs may appear to behave like any non-magnetic material;\nHowever, such a seemingly mundane macroscopic magnetic property is highly\nnontrivial at microscopic level, where opposite spin alignment within the AFM\nunit cell forms a rich internal structure. In topological AFMs, such an\ninternal structure leads to a new possibility, where topology and Berry phase\ncan acquire distinct spatial textures. Here, we study this exciting possibility\nin an AFM Axion insulator, even-layered MnBi$_2$Te$_4$ flakes, where spatial\ndegrees of freedom correspond to different layers. Remarkably, we report the\nobservation of a new type of Hall effect, the layer Hall effect, where\nelectrons from the top and bottom layers spontaneously deflect in opposite\ndirections. Specifically, under no net electric field, even-layered\nMnBi$_2$Te$_4$ shows no anomalous Hall effect (AHE); However, applying an\nelectric field isolates the response from one layer and leads to the surprising\nemergence of a large layer-polarized AHE (~50%$\\frac{e^2}{h}$). Such a layer\nHall effect uncovers a highly rare layer-locked Berry curvature, which serves\nas a unique character of the space-time $\\mathcal{PT}$-symmetric AFM\ntopological insulator state. Moreover, we found that the layer-locked Berry\ncurvature can be manipulated by the Axion field, E$\\cdot$B, which drives the\nsystem between the opposite AFM states. Our results achieve previously\nunavailable pathways to detect and manipulate the rich internal spatial\nstructure of fully-compensated topological AFMs. The layer-locked Berry\ncurvature represents a first step towards spatial engineering of Berry phase,\nsuch as through layer-specific moir\\'e potential.",
        "positive": "Morphological evolution in a strained-heteroepitaxial solid droplet on a\n  rigid substrate: Dynamical simulations: A systematic study based on the self-consistent dynamical simulations is\npresented for the spontaneous evolution of flat solid droplets (bumps), which\nare driven by the surface drift diffusion induced by the capillary and mismatch\nstresses, during the development of the Stranski-Krastanow island morphology on\na rigid substrate. The physico-mathematical model, which bases on the\nirreversible thermodynamics treatment of surfaces and interfaces with\nsingularities (Ogurtani, T.O., J. Chem. Phys. 124, 144706, 2006) furnishes us\nto have auto-control on the otherwise free-motion of the triple junction\ncontour line between the substrate and the droplet without presuming any\nequilibrium dihedral contract (wetting) angles at the edges. During the\ndevelopment of Stranski-Krastanow islands through the mass accumulation at the\ncentral region of the droplet via surface drift-diffusion with and/or without\ngrowth, the formation of an extremely thin wetting layer is observed. . This\nwetting layer has a thickness of a fraction of a nanometer and covers not only\nthe initial computation domain but also its further extension beyond the\noriginal boundaries. Above a certain threshold level of the mismatch strain\nand/or the size (i.e. volume) of the droplets, which depends on the initial\nphysicochemical data and the aspect ratio (i.e., shape) of the original\ndroplet, the formation of the multiple islands separated by the shallow wetting\nlayers is also observed"
    },
    {
        "anchor": "Cluster assimilation and collisional filtering on metal-oxide surfaces: We present the first ab initio molecular dynamics study of collisions between\nmetal-oxide clusters and surfaces. The resulting trajectories reveal that the\ninternal degrees of freedom of the cluster play a defining role in collision\noutcome. The phase space of incoming internal temperature and translational\nenergy exhibits regions where the collision process itself ensures that each\ncluster which does not rebound from the surface assimilates seamlessly onto it\nupon impact. This filtering may explain recent observations of a \"fast\nsmoothing mechanism\" during pulsed laser deposition.",
        "positive": "Spin Space Group Theory and Unconventional Magnons in Collinear Magnets: Topological magnons have received substantial interest for their potential in\nboth fundamental research and device applications due to their exotic uncharged\nyet topologically protected boundary modes. However, their understanding has\nbeen impeded by the lack of fundamental symmetry descriptions of magnetic\nmaterials, of which the spin Hamiltonians are essentially determined by the\nisotropic Heisenberg interaction. The corresponding magnon band structures\nallows for more symmetry operations with separated spin and spatial operations,\nforming spin space groups (SSGs), than the conventional magnetic space groups.\nHere we developed spin space group (SSG) theory to describe collinear magnetic\nconfigurations, identifying all the 1421 collinear SSGs and categorizing them\ninto four types, constructing band representations for these SSGs, and\nproviding a full tabulation of SSGs with exotic nodal topology. Our\nrepresentation theory perfectly explains the band degeneracies of previous\nexperiments and identifies new magnons beyond magnetic space groups with\ntopological charges, including duodecuple point, octuple nodal line and\ncharge-4 octuple point. With an efficient algorithm that diagnoses topological\nmagnons in collinear magnets, our work offers new pathways to exploring exotic\nphenomena of magnonic systems, with the potential to advance the\nnext-generation spintronic devices."
    },
    {
        "anchor": "A combined first-principles and thermodynamic approach to M-Nitronyl\n  Nitroxide (M=Co, Mn) spin helices: The properties of two molecular-based magnetic helices, composed of 3$d$\nmetal Co and Mn ions bridged by Nitronyl Nitroxide radicals, are investigated\nby density functional calculations. Their peculiar and distinctive magnetic\nbehavior is here elucidated by a thorough description of their magnetic,\nelectronic, and anisotropy properties. Metal ions are antiferromagnetically\ncoupled with the radicals, leading to a ferrimagnetically ordered ground state.\nA strong metal-radical exchange coupling is found, about 44 meV and 48 meV for\nCo- and Mn-helices, respectively. The latter have also relevant\nnext-nearest-neighbor Mn-Mn antiferromagnetic interactions (of $\\sim$ 6 meV).\nCo-sites are characterized by non-collinear uniaxial anisotropies, whereas\nMn-sites are rather isotropic. A key result pertains to the Co-helix: the\nmicroscopic picture resulting from density-functional calculations allows us to\npropose a spin Hamiltonian of increased complexity with respect to the commonly\nemployed Ising Hamiltonian, suitable for the study of finite-temperature\nbehavior, and that seems to clarify the puzzling scenario of multiple\ncharacteristic energy scales observed in experiments.",
        "positive": "Multifractal analysis of the fracture surfaces of foamed\n  polypropylene/polyethylene blends: The two-dimensional multifractal detrended fluctuation analysis is applied to\nreveal the multifractal properties of the fracture surfaces of foamed\npolypropylene/polyethylene blends at different temperatures. Nice power-law\nscaling relationship between the detrended fluctuation function $F_{q}$ and the\nscale $s$ is observed for different orders $q$ and the scaling exponent $h(q)$\nis found to be a nonlinear function of $q$, confirming the presence of\nmultifractality in the fracture surfaces. The multifractal spectra $f(\\alpha)$\nare obtained numerically through Legendre transform. The shape of the\nmultifractal spectrum of singularities can be well captured by the width of\nspectrum $\\Delta\\alpha$ and the difference of dimension $\\Delta f$. With the\nincrease of the PE content, the fracture surface becomes more irregular and\ncomplex, as is manifested by the facts that $\\Delta\\alpha$ increases and\n$\\Delta f$ decreases from positive to negative. A qualitative interpretation is\nprovided based on the foaming process."
    },
    {
        "anchor": "Evidence for the Presence of Spin Accumulation in Localized States at\n  Ferromagnet-Silicon Interfaces: We experimentally show evidence for the presence of spin accumulation in\nlocalized states at ferromagnet-silicon interfaces, detected by electrical\nHanle effect measurements in CoFe/$n^{+}$-Si/$n$-Si lateral devices. By\ncontrolling the measurement temperature, we can clearly observe marked changes\nin the spin-accumulation signals at low temperatures, at which the electron\ntransport across the interface changes from the direct tunneling to the\ntwo-step one via the localized states. We discuss in detail the difference in\nthe spin accumulation between in the Si channel and in the localized states.",
        "positive": "Strong Spin-Orbit Torque effect on magnetic defects due to topological\n  surface state electrons in Bi$_{2}$Te$_{3}$: We investigate the spin-orbit torque exerted on the magnetic moments of the\ntransition-metal impurities Cr, Mn, Fe and Co, embedded in the surface of the\ntopological insulator Bi$_{2}$Te$ _{3} $, in response to an electric field and\na consequent electrical current flow in the surface. The multiple scattering\nproblem of electrons off impurity atoms is solved by first-principles\ncalculations within the full-potential relativistic Korringa-Kohn-Rostoker\n(KKR) Green function method, while the spin-orbit torque calculations are\ncarried out by combining the KKR method with the semiclassical Boltzmann\ntransport equation. We analyze the correlation of the spin-orbit torque to the\nspin accumulation and spin flux in the defects. We compare the torque on\ndifferent magnetic impurities and unveil the effect of resonant scattering. In\naddition, we calculate the resistivity and the Joule heat as a function of the\ntorque in these systems. We predict that the Mn/Bi$_{2}$Te$_{3}$ is optimal\namong the studied systems."
    },
    {
        "anchor": "Pulsed sputtering during homoepitaxial surface growth: layer-by-layer\n  forever: The homoepitaxial growth of initially flat surfaces has so far always led to\nsurfaces which become rougher and rougher as the number of layers increases:\neven in systems exhibiting ``layer by layer'' growth the registry of the layers\nis gradually lost. We propose that pulsed glancing-angle sputtering, once per\nmonolayer, can in principle lead to layer-by-layer growth that continues\nindefinitely, if one additional parameter is controlled. We illustrate our\nsuggestion with a fairly realistic simulation of the growth of a Pt (111)\nsurface, coupled with a simplified model for the sputtering process.",
        "positive": "Magnetic excitations in the Kagome staircase compounds: Inelastic neutron scattering measurements have been performed on single\ncrystal samples of Co3V2O8 and Ni3V2O8. The magnetic system in these compounds\nis believed to be frustrated, as the magnetic ions Co2+ with S=3/2 and Ni2+\nwith S=1 adopt a buckled version of the Kagome lattice. Magnetic excitations\nhave been observed in both samples using a time-of-flight neutron spectrometer.\nThe excitation spectrum is dispersive for both samples and has a considerable\ngap in the low temperature phases, while the intermediate temperature phases\nare marked by a significant softening of the excitations energy."
    },
    {
        "anchor": "Molecular hydrogen in silicon: A path-integral simulation: Molecular hydrogen in silicon has been studied by path-integral molecular\ndynamics simulations in the canonical ensemble. Finite-temperature properties\nof these point defects were analyzed in the range from 300 to 900 K.\nInteratomic interactions were modeled by a tight-binding potential fitted to\ndensity-functional calculations. The most stable position for these impurities\nis found at the interstitial T site, with the hydrogen molecule rotating freely\nin the Si cage. Vibrational frequencies have been obtained from a\nlinear-response approach, based on correlations of atom displacements at finite\ntemperatures. The results show a large anharmonic effect in the stretching\nvibration, omega_s, which is softened with respect to a harmonic approximation\nby about 300 cm^{-1}. The coupling between rotation and vibration causes an\nimportant decrease in omega_s for rising temperature.",
        "positive": "Large magneto-Seebeck effect in magnetic tunnel junctions with\n  half-metallic Heusler electrodes: Spin caloritronics studies the interplay between charge-, heat- and\nspin-currents, which are initiated by temperature gradients in magnetic\nnanostructures. A plethora of new phenomena has been discovered that promises,\ne.g., to make wasted heat in electronic devices useable or to provide new\nread-out mechanisms for information. However, only few materials have been\nstudied so far with Seebeck voltages of only some {\\mu}V, which hampers\napplications. Here, we demonstrate that half-metallic Heusler compounds are hot\ncandidates for enhancing spin-dependent thermoelectric effects. This becomes\nevident when considering the asymmetry of the spin-split density of electronic\nstates around the Fermi level that determines the spin-dependent thermoelectric\ntransport in magnetic tunnel junctions. We identify Co$_2$FeAl and Co$_2$FeSi\nHeusler compounds as ideal due to their energy gaps in the minority density of\nstates, and demonstrate devices with substantially larger Seebeck voltages and\ntunnel magneto-Seebeck effect ratios than the commonly used Co-Fe-B based\njunctions."
    },
    {
        "anchor": "MSGCorep: A package for corepresentations of magnetic space groups: Motivated by easy access to complete corepresentation (corep) data of all the\n1651 magnetic space groups (MSGs) in three-dimensional space, we have developed\na Mathematica package MSGCorep to provide an offline database of coreps and\nvarious functions to manipulate them, based on our previous package\nSpaceGroupIrep. One can use the package MSGCorep to obtain the elements of any\nMSG and magnetic little group, to calculate the multiplication of group\nelements, to obtain the small coreps at any k-point and full coreps of any\nmagnetic k-star for any MSG and show them in a user-friendly table form, to\ncalculate and show the decomposition of direct products of full coreps between\nany two specified magnetic k-stars, and to determine the small coreps of energy\nbands. Both single-valued and double-valued coreps are supported. In addition,\nthe 122 magnetic point groups (MPGs) and their coreps are also supported by\nthis package. To the best of our knowledge, MSGCorep is the first package that\nis able to calculate the direct product of full coreps for any MSG and able to\ndetermine small coreps of energy bands for general purpose. In a word, the\nMSGCorep package is an offline database and tool set for MSGs, MPGs, and their\ncoreps, and it is very useful to study the symmetries in magnetic and\nnonmagnetic materials.",
        "positive": "Experimental evidence for an intermediate phase in the multiferroic\n  YMnO3: We have studied YMnO$_{3}$ by high-temperature synchrotron X-ray powder\ndiffraction, and have carried out differential thermal analysis and dilatometry\non a single crystal sample. These experiments show two phase transitions at\nabout 1100K and 1350K, respectively. This demonstrates the existence of an\nintermediate phase between the room temperature ferroelectric and the high\ntemperature centrosymmetric phase. This study identifies for the first time the\ndifferent high-temperature phase transitions in YMnO$_{3}$."
    },
    {
        "anchor": "An investigation of the inverted Hanle effect in highly-doped Si: The underlying physics of the inverted Hanle effect appearing in Si was\nexperimentally investigated using a Si spin valve, where spin transport was\nrealized up to room temperature. No inverted-Hanle-related signal was observed\nin a non-local 4-terminal scheme even the same ferromagnetic electrode was\nused, whereas the signal was detected in a non-local 3-terminal scheme.\nAlthough the origin of the inverted Hanle effect has been thought to be\nascribed to interfacial roughness beneath a ferromagnetic electrode, our\nfinding is inconsistent with the conventional interpretation. More importantly,\nwe report that there were two different Hanle signals in a non-local 3-terminal\nscheme, one of which corresponds to the inverted Hanle signal but the other is\nascribed to spin transport. These results strongly suggest that (1) there is\nroom for discussion concerning the origin of the inverted Hanle effect, and (2)\nachievement of spin transport in a non-local 4-terminal scheme is indispensable\nfor further understanding of spin injection, spin transport and spin coherence\nin Si. Our new findings provide a new and strong platform for arising\ndiscussion of the physical essence of Hanle-related spin phenomena.",
        "positive": "Band structures in coupled-cluster singles-and-doubles Green's function\n  (GFCCSD): We demonstrate that coupled-cluster singles-and-doubles Green's function\n(GFCCSD) method is a powerful and prominent tool drawing the electronic band\nstructures and the total energies, which many theoretical techniques struggle\nto reproduce. We have calculated single-electron energy spectra via GFCCSD\nmethod for various kinds of systems, ranging from ionic to covalent and van der\nWaals, for the first time: one-dimensional LiH chain, one-dimensional C chain,\nand one-dimensional Be chain. We have found that the band gap becomes narrower\nthan in HF due to the correlation effect. We also show that the band structures\nobtained from GFCCSD method include both quasiparticle and satellite peaks\nsuccessfully. Besides, taking one-dimensional LiH as an example, we discuss the\nvalidity of restricting the active space to suppress the computational cost of\nGFCCSD method while maintaining the accuracy. We show that the calculated\nresults without bands that do not contribute to the chemical bonds are in good\nagreement with full-band calculations. With GFCCSD method, we can calculate the\ntotal energy and band structures with high precision."
    },
    {
        "anchor": "Transport properties of n-type ultrananocrystalline diamond films: We investigate transport properties of ultrananocrystalline diamond films for\na broad range of temperatures. Addition of nitrogen during plasma-assisted\ngrowth increases the conductivity of ultrananocrystalline diamond films by\nseveral orders of magnitude. We show that films produced at low concentration\nof nitrogen in the plasma are very resistive and electron transport occurs via\na variable range hopping mechanism while in films produced at high nitrogen\nconcentration the electron states become delocalized and the transport\nproperties of ultrananocrystalline diamond films can be described using the\nBoltzmann formalism. We discuss the critical concentration of carriers at which\nthe metal to insulator transition in ultrananocrystalline diamond films occurs\nand compare our results with available experimental data.",
        "positive": "Non-Contact Measurement of Thermal Diffusivity in Ion-Implanted Nuclear\n  Materials: Knowledge of mechanical and physical property evolution due to irradiation\ndamage is essential for the development of future fission and fusion reactors.\nIon-irradiation provides an excellent proxy for studying irradiation damage,\nallowing high damage doses without sample activation. Limited\nion-penetration-depth means that only few-micron-thick damaged layers are\nproduced. Substantial effort has been devoted to probing the mechanical\nproperties of these thin implanted layers. Yet, whilst key to reactor design,\ntheir thermal transport properties remain largely unexplored due to a lack of\nsuitable measurement techniques. Here we demonstrate non-contact thermal\ndiffusivity measurements in ion-implanted tungsten for nuclear fusion armour.\nAlloying with transmutation elements and the interaction of retained gas with\nimplantation-induced defects both lead to dramatic reductions in thermal\ndiffusivity. These changes are well captured by our modelling approaches. Our\nobservations have important implications for the design of future fusion power\nplants."
    },
    {
        "anchor": "Direct observation of the ice rule in artificial kagome spin ice: Recently, significant interest has emerged in fabricated systems that mimic\nthe behavior of geometrically-frustrated materials. We present the full\nrealization of such an artificial spin ice system on a two-dimensional kagome\nlattice and demonstrate rigid adherence to the local ice rule by directly\ncounting individual pseudo-spins. The resulting spin configurations show not\nonly local ice rules and long-range disorder, but also correlations consistent\nwith spin ice Monte Carlo calculations. Our results suggest that dipolar\ncorrections are significant in this system, as in pyrochlore spin ice, and they\nopen a door to further studies of frustration in general.",
        "positive": "Accelerate Microstructure Evolution Simulation Using Graph Neural\n  Networks with Adaptive Spatiotemporal Resolution: Surrogate models driven by sizeable datasets and scientific machine-learning\nmethods have emerged as an attractive microstructure simulation tool with the\npotential to deliver predictive microstructure evolution dynamics with huge\nsavings in computational costs. Taking 2D and 3D grain growth simulations as an\nexample, we present a completely overhauled computational framework based on\ngraph neural networks with not only excellent agreement to both the ground\ntruth phase-field methods and theoretical predictions, but enhanced accuracy\nand efficiency compared to previous works based on convolutional neural\nnetworks. These improvements can be attributed to the graph representation,\nboth improved predictive power and a more flexible data structure amenable to\nadaptive mesh refinement. As the simulated microstructures coarsen, our method\ncan adaptively adopt remeshed grids and larger timesteps to achieve further\nspeedup. The data-to-model pipeline with training procedures together with the\nsource codes are provided."
    },
    {
        "anchor": "Domain walls in helical magnets: The structure of domain walls determines to a large extent the properties of\nmagnetic materials, in particular their hardness and switching behavior, it\nrepresents an essential ingredient of spintronics. Common domain walls are of\nBloch and Neel types in which the magnetization rotates around a fixed axis,\ngiving rise to a one-dimensional magnetization profile. Domain walls in helical\nmagnets, most relevant in multiferroics, were never studied systematically.\nHere we show that domain walls in helical magnets are fundamentally different\nfrom Bloch and Neel walls. They are generically characterized by a\ntwo-dimensional pattern formed by a regular lattice of vortex singularities. In\nconical phases vortices carry Berry phase flux giving rise to the anomalous\nHall effect. In multiferroics vortices are charged, allowing to manipulate\nmagnetic domain walls by electric fields. Our theory allows the interpretation\nof magnetic textures observed in helical magnetic structures.",
        "positive": "Magnetism and Spin Dynamics in Room-Temperature van der Waals Magnet\n  Fe$_5$GeTe$_2$: Two-dimensional (2D) van der Waals (vdWs) materials have gathered a lot of\nattention recently. However, the majority of these materials have Curie\ntemperatures that are well below room temperature, making it challenging to\nincorporate them into device applications. In this work, we synthesized a\nroom-temperature vdW magnetic crystal Fe$_5$GeTe$_2$ with a Curie temperature\nT$_c = 332$ K, and studied its magnetic properties by vibrating sample\nmagnetometry (VSM) and broadband ferromagnetic resonance (FMR) spectroscopy.\nThe experiments were performed with external magnetic fields applied along the\nc-axis (H$\\parallel$c) and the ab-plane (H$\\parallel$ab), with temperatures\nranging from 300 K to 10 K. We have found a sizable Land\\'e g-factor difference\nbetween the H$\\parallel$c and H$\\parallel$ab cases. In both cases, the Land\\'e\ng-factor values deviated from g = 2. This indicates contribution of orbital\nangular momentum to the magnetic moment. The FMR measurements reveal that\nFe$_5$GeTe$_2$ has a damping constant comparable to Permalloy. With reducing\ntemperature, the linewidth was broadened. Together with the VSM data, our\nmeasurements indicate that Fe$_5$GeTe$_2$ transitions from ferromagnetic to\nferrimagnetic at lower temperatures. Our experiments highlight key information\nregarding the magnetic state and spin scattering processes in Fe$_5$GeTe$_2$,\nwhich promote the understanding of magnetism in Fe$_5$GeTe$_2$, leading to\nimplementations of Fe$_5$GeTe$_2$ based room-temperature spintronic devices."
    },
    {
        "anchor": "Atomic layer doping of Mn magnetic impurities from surface chains at a\n  Ge/Si hetero-interface: We realize Mn $\\delta$-doping into Si and Si/Ge interfaces using Mn atomic\nchains on Si(001). Highly sensitive X-ray absorption fine structure techniques\nreveal that encapsulation at room temperature prevents the formation of\nsilicides / germanides whilst maintaining one dimensional anisotropic\nstructures. This is revealed by studying both the incident X-ray polarization\ndependence and post-annealing effects. Density functional theory calculations\nsuggest that Mn atoms are located at substitutional sites, and show good\nagreement with experiment. A comprehensive magnetotransport study reveals\nmagnetic ordering within the Mn $\\delta$-doped layer, which is present at\naround 120\\,K. We demonstrate that doping methods based on the burial of\nsurface nanostructures allows for the realization of systems for which\nconventional doping methods fail.",
        "positive": "Band Structure, Band Offsets, Substitutional Doping, and Schottky\n  Barriers in InSe: We present a comprehensive study of the electronic structure of the layered\nsemiconductor InSe using density functional theory. We calculate the band\nstructure of the monolayer and bulk material with the band gap corrected using\nhybrid functionals. The band gap of the monolayer is 2.4 eV. The band edge\nstates are surprising isotropic. The electron affinities and band offsets are\nthen calculated for heterostructures as would be used in tunnel field effect\ntransistors (TFETs). The ionization potential of InSe is quite large, similar\nto that of HfSe2 or SnSe2, and so InSe is suitable to act as the drain in the\nTFET. The intrinsic defects are then calculated. For Se-rich layers, the Se\nadatom is the lowest energy defect, whereas for In-rich layers, the In adatom\nis most stable for Fermi energies across most of the gap. Both substitutional\ndonors and acceptors are calculated to be shallow, and not reconstructed.\nFinally, the Schottky barriers of metals are found to be strongly pinned, with\nthe Fermi level pinned by metal induced gap states about 0.5 eV above the\nvalence band edge."
    },
    {
        "anchor": "Defects and Phase Formation in Non-Stoichiometric LaFeO$_3$: a Combined\n  Theoretical and Experimental Study: The defect chemistry of perovskite compounds is directly related to the\nstoichiometry and to the valence states of the transition-metal ions. Defect\nengineering has become increasingly popular as it offers the possibility to\ninfluence the catalytic properties of perovskites for applications in energy\nstorage and conversion devices such as solid-oxide fuel- and electrolyzer\ncells. LaFeO$_3$ (LFO) can be regarded as a base compound of the family of\ncatalytically active perovskites La$_{1-x}$A$_x$Fe$_{1-y}$B$_y$O$_{3-\\delta}$,\nfor which the defect chemistry as well as the electronic and ionic conductivity\ncan be tuned by substitution on cationic sites. Combining theoretical and\nexperimental approaches, we explore the suitability for A-site vacancy\nengineering, namely the feasibility of actively manipulating the valence state\nof Fe and the concentration of point defects by synthesizing La-deficient LFO.\nFormation energies and concentrations of point defects were determined as a\nfunction of processing conditions by first-principles DFT+U calculations. Based\non the results, significant compositional deviations from stoichiometric LFO\ncannot be expected by providing rich or poor conditions of the oxidic precursor\ncompounds (Fe$_2$O$_3$ and La$_2$O$_3$) in a solid-state processing route. In\nthe experimental part, LFO was synthesized with a targeted La-site deficiency.\nWe analyze the resulting phases by X-ray diffraction and scanning electron\nmicroscopy, (scanning) transmission electron microscopy in combination with\nenergy-dispersive X-ray spectroscopy, and electron energy-loss spectrometry.\nInstead of a variation of the La/Fe ratio, a mixture of the two phases\nFe$_2$O$_3$ and LFO was observed, resulting in an invariant charge state of Fe,\nin line with the theoretical results. We discuss our findings with respect to\npartly differing assumptions made in previous studies on this material system.",
        "positive": "Ferroelectric order associated with an ordered occupancy at the\n  octahedral site of the inverse spinel structure of multiferroic NiFe2O4: We report a ferroelectric order at ~ 98 K for NiFe2O4, which carries an\ninverse spinel structure with a centrosymmetric Fd3m structure at room\ntemperature. The value of spontaneous electric polarization is considerably\nhigh as ~ 0.29 {\\mu}C/cm2 for 5 kV/cm poling field. The electric polarization\ndecreases considerably (~ 17 %) around liquid nitrogen temperature upon\napplication of 50 kOe field, proposing a significant magnetoelectric coupling.\nThe synchrotron diffraction studies confirm a structural transition at ~ 98 K\nto a noncentrosymmetric structure of P4122 space group. The occurrence of polar\norder is associated with an ordered occupancy of Ni and Fe atoms at the\noctahedral sites of the P4122 structure, instead of random occupancies at the\noctahedral site of the inverse spinel structure. The results propose that\nNiFe2O4 is a new type-II multiferroic material."
    },
    {
        "anchor": "Van der Waals interaction between two crossed carbon nanotubes: The analytical expressions for the van der Waals potential energy and force\nbetween two crossed carbon nanotubes are presented. The Lennard-Jones potential\nfor two carbon atoms and the method of the smeared out approximation suggested\nby L.A. Girifalco were used. The exact formula is expressed in terms of\nrational and elliptical functions. The potential and force for carbon nanotubes\nwere calculated. The uniform potential curves for single- and multi- wall\nnanotubes were plotted. The equilibrium distance, maximal attractive force, and\npotential energy have been estimated.",
        "positive": "Ferromagnetism and infrared electrodynamics of Ga$_{1-x}$Mn$_{x}$As}: We report on the magnetic and the electronic properties of the prototype\ndilute magnetic semiconductor Ga$_{1-x}$Mn$_x$As using infrared (IR)\nspectroscopy. Trends in the ferromagnetic transition temperature $T_C$ with\nrespect to the IR spectral weight are examined using a sum-rule analysis of IR\nconductivity spectra. We find non-monotonic behavior of trends in $T_C$ with\nthe spectral weight to effective Mn ratio, which suggest a strong\ndouble-exchange component to the FM mechanism, and highlights the important\nrole of impurity states and localization at the Fermi level. Spectroscopic\nfeatures of the IR conductivity are tracked as they evolve with temperature,\ndoping, annealing, As-antisite compensation, and are found only to be\nconsistent with an Mn-induced IB scenario. Furthermore, our detailed\nexploration of these spectral features demonstrates that seemingly conflicting\ntrends reported in the literature regarding a broad mid-IR resonance with\nrespect to carrier density in Ga$_{1-x}$Mn$_x$As are in fact not contradictory.\nOur study thus provides a consistent experimental picture of the magnetic and\nelectronic properties of Ga$_{1-x}$Mn$_x$As."
    },
    {
        "anchor": "Excited-state spin-resonance spectroscopy of V$_\\text{B}^-$ defect\n  centers in hexagonal boron nitride: The recently discovered spin-active boron vacancy (V$_\\text{B}^-$) defect\ncenter in hexagonal boron nitride (hBN) has high contrast optically-detected\nmagnetic resonance (ODMR) at room-temperature, with a spin-triplet ground-state\nthat shows promise as a quantum sensor. Here we report temperature-dependent\nODMR spectroscopy to probe spin within the orbital excited-state. Our\nexperiments determine the excited-state spin Hamiltonian, including a\nroom-temperature zero-field splitting of 2.1 GHz and a g-factor similar to that\nof the ground-state. We confirm that the resonance is associated with spin\nrotation in the excited-state using pulsed ODMR measurements, and we observe\nZeeman-mediated level anti-crossings in both the orbital ground- and\nexcited-state. Our observation of a single set of excited-state spin-triplet\nresonance from 10 to 300 K is consistent with an orbital-singlet, which has\nconsequences for understanding the symmetry of this defect. Additionally, the\nexcited-state ODMR has strong temperature dependence of both contrast and\ntransverse anisotropy splitting, enabling promising avenues for quantum\nsensing.",
        "positive": "MetaNOR: A Meta-Learnt Nonlocal Operator Regression Approach for\n  Metamaterial Modeling: We propose MetaNOR, a meta-learnt approach for transfer-learning operators\nbased on the nonlocal operator regression. The overall goal is to efficiently\nprovide surrogate models for new and unknown material-learning tasks with\ndifferent microstructures. The algorithm consists of two phases: (1) learning a\ncommon nonlocal kernel representation from existing tasks; (2) transferring the\nlearned knowledge and rapidly learning surrogate operators for unseen tasks\nwith a different material, where only a few test samples are required. We apply\nMetaNOR to model the wave propagation within 1D metamaterials, showing\nsubstantial improvements on the sampling efficiency for new materials."
    },
    {
        "anchor": "Topological electronic structure in the antiferromagnet HoSbTe: Magnetic topological materials, in which the time-reversal symmetry is\nbroken, host various exotic quantum phenomena, including the quantum anomalous\nHall effect, axion insulator states, and Majorana fermions. The study of\nmagnetic topological materials is at the forefront of condensed matter physics.\nRecently, a variety of magnetic topological materials have been reported, such\nas Mn$_3$Sn, Co$_3$Sn$_2$S$_2$, Fe$_3$Sn$_2$, and MnBi$_2$Te$_4$. Here, we\nreport the observation of a topological electronic structure in an\nantiferromagnet, HoSbTe, a member of the ZrSiS family of materials, by\nangle-resolved photoemission spectroscopy measurements and first-principles\ncalculations. We demonstrate that HoSbTe is a Dirac nodal line semimetal when\nspin-orbit coupling (SOC) is neglected. However, our theoretical calculations\nshow that the strong SOC in HoSbTe fully gaps out the nodal lines and drives\nthe system to a weak topological insulator state, with each layer being a\ntwo-dimensional topological insulator. Because of the strong SOC in HoSbTe, the\ngap is as large as hundreds of meV along specific directions, which is directly\nobserved by our ARPES measurements. The existence of magnetic order and\ntopological properties in HoSbTe makes it a promising material for realization\nof exotic quantum devices.",
        "positive": "Electromagnetic-Polarization Selective Composites with Quasi-1D van der\n  Waals Metallic Fillers: We report on the preparation of flexible polymer composite films with aligned\nmetallic fillers comprised of atomic chain bundles of the quasi-one-dimensional\n(1D) van der Waals material tantalum triselenide, TaSe3. The material\nfunctionality, embedded at the nanoscale level, is achieved by mimicking the\ndesign of an electromagnetic aperture grid antenna. The processed composites\nemploy chemically exfoliated TaSe3 nanowires as the grid building blocks\nincorporated within the thin film. Filler alignment is achieved using the\n\"blade coating\" method. Measurements conducted in the X-band frequency range\ndemonstrate that the electromagnetic transmission through such films can be\nvaried significantly by changing the relative orientations of the quasi-1D\nfillers and the polarization of the electromagnetic wave. We argue that such\npolarization-sensitive polymer films with quasi-1D fillers are applicable to\nadvanced electromagnetic interference shielding in future communication\nsystems."
    },
    {
        "anchor": "Electronic and phononic properties of the chalcopyrite CuGaS2: The availability of ab initio electronic calculations and the concomitant\ntechniques for deriving the corresponding lattice dynamics have been profusely\nused for calculating thermodynamic and vibrational properties of\nsemiconductors, as well as their dependence on isotopic masses. The latter have\nbeen compared with experimental data for elemental and binary semiconductors\nwith different isotopic compositions. Here we present theoretical and\nexperimental data for several vibronic and thermodynamic properties of CuGa2, a\ncanonical ternary semiconductor of the chalcopyrite family. Among these\nproperties are the lattice parameters, the phonon dispersion relations and\ndensities of states (projected on the Cu, Ga, and S constituents), the specific\nheat and the volume thermal expansion coefficient. The calculations were\nperformed with the ABINIT and VASP codes within the LDA approximation for\nexchange and correlation and the results are compared with data obtained on\nsamples with the natural isotope composition for Cu, Ga and S, as well as for\nisotope enriched samples.",
        "positive": "Second order classical perturbation theory for atom surface scattering:\n  analysis of asymmetry in the angular distribution: A second order classical perturbation theory is developed and applied to\nelastic atom corrugated surface scattering. The resulting theory accounts for\nexperimentally observed asymmetry in the final angular distributions. These\ninclude qualitative features, such as reduction of the asymmetry with increased\nincidence energy as well as asymmetry in the location of the rainbow peaks with\nrespect to the specular scattering angle. The theory is especially applicable\nto \"soft\" corrugated potentials. Analytic expressions for the angular\ndistribution are derived for the exponential repulsive and Morse potential\nmodels. The theory is implemented numerically to a simplified model of the\nscattering of an Ar atom from a LiF(100) surface."
    },
    {
        "anchor": "Machine Learning Enabled Computational Screening of Inorganic Solid\n  Electrolytes for Dendrite Suppression with Li Metal Anode: Next generation batteries based on lithium (Li) metal anodes have been\nplagued by the dendritic electrodeposition of Li metal on the anode during\ncycling, resulting in short circuit and capacity loss. Suppression of dendritic\ngrowth through the use of solid electrolytes has emerged as one of the most\npromising strategies for enabling the use of Li metal anodes. We perform a\ncomputational screening of over 12,000 inorganic solids based on their ability\nto suppress dendrite initiation in contact with Li metal anode. Properties for\nmechanically isotropic and anisotropic interfaces that can be used in stability\ncriteria for determining the propensity of dendrite initiation are usually\nobtained from computationally expensive first-principles methods. In order to\nobtain a large dataset for screening, we use machine learning models to predict\nthe mechanical properties of several new solid electrolytes. We train a\nconvolutional neural network on the shear and bulk moduli purely on structural\nfeatures of the material. We use AdaBoost, Lasso and Bayesian ridge regression\nto train the elastic constants, where the choice of the model depended on the\nsize of the training data and the noise that it can handle. Our models give us\ndirect interpretability by revealing the dominant structural features affecting\nthe elastic constants. The stiffness is found to increase with a decrease in\nvolume per atom, increase in minimum anion-anion separation, and increase in\nsublattice (all but Li) packing fraction. Cross-validation/test performance\nsuggests our models generalize well. We predict over 20 mechanically\nanisotropic interfaces between Li metal and 6 solid electrolytes which can be\nused to suppress dendrite growth. Our screened candidates are generally soft\nand highly anisotropic, and present opportunities for simultaneously obtaining\ndendrite suppression and high ionic conductivity in solid electrolytes.",
        "positive": "Magnetocrystalline Anisotropy of Fe-based $L1_0$ Alloys: Validity of\n  Approximate Methods to Treat the Spin-Orbit Interaction: First-principles calculations are used to gauge different levels of\napproximation to calculate the magnetocrystalline anisotropy energies (MAE) of\nfive $L1_0$ FeMe alloys (Me=Co, Cu, Pd, Pt, Au). We find that a second-order\nperturbation (2PT) treatment of the spin-orbit interaction (SOI) breaks down\nfor the alloys containing heavier ions, while it provides a very accurate\ndescription of the MAE behaviour of FeCo, FeCu, and FePd. Moreover, the\nrobustness of the 2PT approximation is such that in these cases it accounts for\nthe MAE of highly-non-neutral alloys and, thus, it can be used to predict their\nperformance when dopants are present or when they are subject to applied gate\nbias, which are typical conditions in working magnetoelectric devices. We also\nobserve that switching of the easy axis direction can be induced in some of\nthese alloys by addition or removal of, at least, one electron per cell. In all\ncases, the details of the bandstructure are responsible for the finally\nobserved MAE value and, therefore, suggest a limited predicting power of models\nbased on the expected orbital moment values and bandwidths. Finally, we have\nconfirmed the importance of various calculation parameters to obtain converged\nMAE values, in particular, those related to the accuracy of the Fermi level\ndetermination."
    },
    {
        "anchor": "Engineered electronic states in atomically precise artificial lattices\n  and graphene nanoribbons: The fabrication of atomically precise structures with designer electronic\nproperties is one of the emerging topics in condensed matter physics. The\nrequired level of structural control can either be reached through atomic\nmanipulation using the tip of a scanning tunneling microscope (STM) or by\nbottom-up chemical synthesis. In this review, we focus on recent progress in\nconstructing novel, atomically precise artificial materials: artificial\nlattices built through atom manipulation and graphene nanoribbons (GNRs)\nrealized by on-surface synthesis. We summarize the required theoretical\nbackground and the latest experiments on artificial lattices, topological\nstates in one-dimensional lattices, experiments on graphene nanoribbons and\ngraphene nanoribbon heterostructures, and topological states in graphene\nnanoribbons. Finally, we conclude our review with an outlook to designer\nquantum materials with engineered electronic structure.",
        "positive": "Liquid-crystal-like dynamic transition in ferroelectric/dielectric\n  superlattices: Nanostructured ferroelectrics display exotic multidomain configurations\nresulting from the electrostatic and elastic boundary conditions they are\nsubject to. While the ferroelectric domains appear frozen in experimental\nimages, atomistic second-principles studies suggest that they may become\nspontaneously mobile upon heating, with the polar order {\\sl melting} in a\nliquid-like fashion. Here we run molecular dynamics simulations of model\nsystems (PbTiO$_3$/SrTiO$_3$ superlattices) to study the unique features of\nthis transformation. Most notably, we find that the multidomain state looses\nits translational and orientational orders at different temperatures,\nresembling the behavior of liquid crystals and yielding an intermediate\nhexatic-like phase. Our simulations reveal the mechanism responsible for the\nmelting and allow us to characterize the stochastic dynamics in the\nhexatic-like phase: we find evidence that it is thermally activated, with\ndomain reorientation rates that grow from tens of gigahertzs to terahertzs in a\nnarrow temperature window."
    },
    {
        "anchor": "Quantification of the atomic surfaces and volumes of a metal cluster\n  based on the molecular surface model: The atomic volume and surface are important geometric quantities for\ncalculating various macroscopic physical quantities from atomic models. This\npaper proposes a new analytical method to calculate the atomic volumes and\nsurfaces of a metal cluster. This method adopts metallic radii to describe atom\nsizes and constructs the overall volume/surface by the molecular surface (MS)\nmodel. It divides cluster atoms into two types: interior atoms and boundary\natoms. For an interior atom, the method defines a variational Voronoi cell as\nits volume. For a boundary atom, the method defines the intersection of the\noverall cluster volume and its variational Voronoi cell as its volume. The\natomic surfaces are calculated along with the volume calculations. This new\nmethod considers the effect of atom sizes and can calculate not only the\noverall volume of a cluster but also the individual volume for each atom. This\nmethod provides computational support for multiscale coupled calculations from\nthe microscale to macroscale.",
        "positive": "Edge Channel Interference Controlled by Landau Level Filling: We study the visibility of Aharonov-Bohm interference in an electronic\nMach-Zehnder interferometer (MZI) in the integer quantum Hall regime. The\nvisibility is controlled by the filling factor $\\nu$ and is observed only\nbetween $\\nu \\approx 2.0$ and 1.0, with an unexpected maximum near $\\nu=1.5$.\nThree energy scales extracted from the temperature and voltage dependences of\nthe visibility change in a very similar way with the filling factor, indicating\nthat the different aspects of the interference depend sensitively on the local\nstructure of the compressible and incompressible strips forming the quantum\nHall edge channels."
    },
    {
        "anchor": "Band-gap tuning and optical response of two-dimensional Si$_x$C$_{1-x}$:\n  A first-principles real space study of disordered 2D materials: We present a real-space formulation for calculating the electronic structure\nand optical conductivity of such random alloys based on the Kubo-Greenwood\nformalism interfaced with the augmented space recursion (ASR) [A. Mookerjee, J.\nPhys. C: Solid State Phys. {\\bf 6}, 1340 (1973)] formulated with the\nTight-binding Linear Muffin-tin Orbitals (TB-LMTO) basis with van\nLeeuwen-Baerends corrected exchange (vLB) [Singh et al, Phys. Rev B {\\bf 93},\n085204, (2016)]. This approach has been used to quantitatively analyze the\neffect of chemical disorder on the configuration averaged electronic properties\nand optical response of 2D honeycomb siliphene Si$_{x}$C$_{1-x}$ beyond the\nusual Dirac-cone approximation. We predicted the quantitative effect of\ndisorder on both the electronic-structure and optical response over a wide\nenergy range, and the results discussed in the light of the available\nexperimental and other theoretical data. Our proposed formalism may open up a\nfacile way for planned band gap engineering in opto-electronic applications.",
        "positive": "Nearly-room-temperature ferromagnetism and tunable anomalous Hall effect\n  in atomically thin Fe4CoGeTe2: Itinerant ferromagnetism at room temperature is a key ingredient for spin\ntransport and manipulation. Here, we report the realization of\nnearly-room-temperature itinerant ferromagnetism in Co doped Fe5GeTe2 thin\nflakes. The ferromagnetic transition temperature TC (323 K - 337 K) is almost\nunchanged when thickness is down to 12 nm and is still about 284 K at 2 nm\n(bilayer thickness). Theoretical calculations further indicate that the\nferromagnetism persists in monolayer Fe4CoGeTe2. In addition to the robust\nferromagnetism down to the ultrathin limit, Fe4CoGeTe2 exhibits an unusual\ntemperature- and thickness-dependent intrinsic anomalous Hall effect. We\npropose that it could be ascribed to the dependence of band structure on\nthickness that changes the Berry curvature near the Fermi energy level subtly.\nThe nearly-room-temperature ferromagnetism and tunable anomalous Hall effect in\natomically thin Fe4CoGeTe2 provide opportunities to understand the exotic\ntransport properties of two-dimensional van der Waals magnetic materials and\nexplore their potential applications in spintronics."
    },
    {
        "anchor": "Tailoring magnetic and magnetocaloric properties of martensitic\n  transitions in ferromagnetic Heusler alloys: Ni$_{50}$Mn$_{34}$In$_{16}$ undergoes a martensitic transformation around 250\nK and exhibits a field induced reverse martensitic transformation and\nsubstantial magnetocaloric effects. We substitute small amounts Ga for In,\nwhich are isoelectronic, to carry these technically important properties to\nclose to room temperature by shifting the martensitic transformation\ntemperature.",
        "positive": "Co/AlP/Co, Co/GaN/Co as magnetic tunnel junctions: AlP and GaN are wide band-gap semiconductors (SC) uses in opto-electronic\nindustry as light emitting diodes. Here we investigate it as future perspective\ncandidate for insulating barrier in magnetic tunnel junctions. We employ\ndensity functional theory for ground state electronic properties and\nnon-equilibrium Green's function method for quantum transport and examined\nCo/AlP/Co and Co/GaN/Co MTJs. We find that both AlP and GaN valance band maxima\nare predominantly made with $p_z$-type orbitals while conduction band minima\nare $s$-type symmetry. We find that both AlP and GaN filter $\\Delta_1$ symmetry\nof Bloch states at $\\Gamma$-point and transmission coefficient at any energy\nlevel in-between the band-gap of materials, is mostly driven by $\\Delta_1$\nsymmetry of Bloch states tunnel via $\\Gamma$-point in first Brillouin zones. We\nfind large magneto-resistance $\\sim$300\\% in Co/AlP/Co MTJs at zero-bias. In\nCo/GaN/Co MTJs we find $\\sim$300\\% TMR at 1.25 eV below the Fermi energy\n($E_{F}-1.25$)~eV, while $\\sim$10\\% TMR around $E_F$ in zero-bias calculations.\nWe notice that both majority and minority $\\Delta_{2'}$ symmetry of Bloch\nstates with rather different $spd$-orbitals compositions tunnel in\nCo[0001]/AlP[0001] MTJs and exhibit non-zero TMR, whereas in Co[111]/GaN[0001]\nMTJs, the both majority and minority $\\Delta_1$ symmetry of Bloch states with\ndifferent energy-gradient tunnels at Fermi energy level along [111] transport\ndirection. Our work accentuate the process for systematic, efficient, accurate\nand versatile framework to design the semiconductors based MTJs for low power\nelectronics."
    },
    {
        "anchor": "Localized segregation of gold in ultra-thin Fe films on Au(001): The growth of up to 10 monolayer-thick Fe films on a Au(001) surface was\ninvestigated during deposition at room temperature and during annealing using\nlow-energy electron diffraction and x-ray photoemission spectroscopy as well as\nlocally with low-energy electron microscopy and photoemission electron\nmicroscopy. The growth proceeds with a submonolayer of Au segregating to the\nsurface of Fe, which is in agreement with previous studies. Annealing was found\nto be critical for the presence of Au on the Fe surface. Our findings show that\nAu segregation proceeds by the formation of cracks in the Fe film, starting at\nthe annealing temperature of 190 {\\deg}C, through which Au diffuses towards the\nsurface. We explain the localized Au segregation with a shadowing effect due to\nthe oblique deposition geometry. As a result, an Fe film with significantly\nimproved roughness, but covered with a Au overlayer, is obtained. This study\nshows the necessity to employ spatially-resolved techniques to fully understand\nthe growth modes of the layered epitaxial systems.",
        "positive": "Possibility of Realizing Quantum Spin Hall Effect at Room Temperature in\n  Stanene/Al2O3(0001): Two-dimensional quantum spin Hall (QSH) insulators with reasonably wide band\ngaps are imperative for the development of various innovative technologies.\nThrough systematic density functional calculations and tight-binding\nsimulations, we found that stanene on {\\alpha}-alumina surface may possess a\nsizeable topologically nontrivial band gap (~0.25 eV) at the {\\Gamma} point.\nFurthermore, stanene is atomically bonded to but electronically decoupled from\nthe substrate, providing high structural stability and isolated QSH states to a\nlarge extent. The underlying physical mechanism is rather general, and this\nfinding may lead to the opening of a new vista for the exploration of QSH\ninsulators for room temperature device applications."
    },
    {
        "anchor": "Pressure induced structural transitions and metallization in Ag2Te: High pressure in-situ synchrotron X-ray diffraction experiments were\nperformed on Ag2Te up to 42.6 GPa at room temperature and four phases were\nidentified. Phase I ({\\beta}-Ag2Te) transformed into phase II at 2.4 GPa, and\nphase III and phase IV emerged at 2.8 GPa and 12.8 GPa respectively. Combined\nwith first-principles calculations, we solved the phase II and phase III\ncrystal structures, and determined the compressional behavior of phase III.\nElectronic band structure calculations show that the insulating phase I with a\nnarrow band gap first transforms into semi metallic phase II with the\nperseverance of topologically non trivial nature, and then to bulk metallic\nphase III. Density of States (DOS) calculations indicate the contrasting\ntransport behavior for Ag2-{\\delta}Te and Ag2+{\\delta}Te under compression. Our\nresults highlight pressure's dramatic role in tuning Ag2Te's electronic band\nstructure, and its novel electrical and magneto transport behaviors.",
        "positive": "Crystal Engineering and Ferroelectricity at the Nanoscale in Epitaxial\n  1D Manganese Oxide on Silicon: Ferroelectric oxides have attracted much attention due to their wide range of\napplications, especially in electronic devices such as nonvolatile memories and\ntunnel junctions. As a result, the monolithic integration of these materials\ninto silicon technology and its nanostructuration to develop alternative\ncost-effective processes are among the central points in current technology. In\nthis work, we used a chemical route to obtain nanowire thin films of a novel\nSr1+{\\delta}Mn8O16 (SMO) hollandite-type manganese oxide on silicon. Scanning\ntransmission electron microscopy combined with crystallographic computing\nreveals a crystal structure comprising hollandite and pyrolusite units sharing\nthe edges of their MnO6 octahedra, resulting in three types of tunnels arranged\nalong the c axis, where ordering of the Sr atoms produces a natural symmetry\nbreaking. The novel structure gives rise to a ferroelectricity and\npiezoelectricity, as revealed by local Direct Piezoelectric Force Microscopy\nmeasurements, which confirmed the ferroelectric nature of SMO nanowire thin\nfilms at room temperature and showed a piezoelectric coefficient d33 value of\n22,6 pC/N. Moreover, we proved that flexible vertical SMO nanowires can be\nharvested and converted into electric output energy through the piezoelectric\neffect, showing an excellent deformability and high interface recombination.\nThis work indicates the possibility of engineering the integration of 1D\nmanganese oxides on silicon, a step which precedes the production of\nmicroelectronic devices."
    },
    {
        "anchor": "Ion-Pairing Limits Crystal Growth in Metal-Oxygen Batteries: Aprotic alkali metal-oxygen batteries are widely considered to be promising\nhigh specific energy alternatives to Li-ion batteries. The growth and\ndissolution of alkali metal oxides such as Li2O2 in Li-O2 batteries and NaO2\nand KO2 in Na- and K-O2 batteries, respectively, is central to the discharge\nand charge processes in these batteries. However, crystal growth and\ndissolution of the discharge products, especially in aprotic electrolytes, is\npoorly understood. In this work, we chose the growth of NaO2 in Na-O2 batteries\nas a model system and show that there is a strong correlation between the\nelectrolyte salt concentration and the NaO2 crystal size. With a combination of\nexperiments and theory, we argue that the correlation is a direct manifestation\nof the strong cation-anion interactions leading to decreased crystal growth\nrate at high salt concentrations. Further, we propose and experimentally\ndemonstrate that cation-coordinating crown molecules are suitable\nelectrochemically stable electrolyte additives that weaken ion-pairing and\nenhance discharge capacities in metal-oxygen batteries while not negatively\naffecting their rechargeability.",
        "positive": "pi-Electron theory of transverse optical excitons in semiconducting\n  single-walled carbon nanotubes: We present a quantitative theory of optical absorption polarized transverse\nto the tube axes in semiconducting single-walled carbon nanotubes. Transverse\noptical absorption in semiconducting single-walled carbon nanotubes is to an\nexciton state that is strongly blueshifted, relative to the two lowest\nlongitudinal excitons, by electron-electron interactions. The binding energy of\nthe transverse exciton is considerably smaller than those of the longitudinal\nexcitons. Electron-electron interactions also reduce the relative oscillator\nstrength of the transverse optical absorption. Our theoretical results are in\nexcellent agreement with recent experimental measurements in four chiral\nnanotubes."
    },
    {
        "anchor": "Large elastic recovery of zinc dicyanoaurate: We report the mechanical properties of the `giant' negative compressibility\nmaterial zinc(II) dicyanoaurate, as determined using a combination of\nsingle-crystal nanoindentation measurements and \\emph{ab initio} density\nfunctional theory calculations. While the elastic response of zinc\ndicyanoaurate is found to be intermediate to the behaviour of dense and open\nframework structures, we discover the material to exhibit a particularly strong\nelastic recovery, which is advantageous for a range of practical applications.\nWe attribute this response to the existence of supramolecular helices that\nfunction as atomic-scale springs, storing mechanical energy during compressive\nstress and hence inhibiting plastic deformation. Our results are consistent\nwith the relationship noted in [Cheng \\& Cheng, \\textit{Appl. Phys. Lett.},\n1998, {\\textbf{73}}, 614] between the magnitude of elastic recovery, on the one\nhand, and the ratio of material hardness to Young's modulus, on the other hand.\nDrawing on comparisons with other metal--organic frameworks containing helical\nstructure motifs, we suggest helices as an attractive supramolecular motif for\nimparting resistance to plastic deformation in the design of functional\nmaterials.",
        "positive": "Raman Study of Layered Breathing Kagome Lattice Semiconductor Nb3Cl8: Niobium chloride (Nb3Cl8) is a layered 2D semiconducting material with many\nexotic properties including a breathing kagome lattice, a topological flat band\nin its band structure, and a crystal structure that undergoes a structural and\nmagnetic phase transition at temperatures below 90 K. Despite being a\nremarkable material with fascinating new physics, the understanding of its\nphonon properties is at its infancy. In this study, we investigate the phonon\ndynamics of Nb3Cl8 in bulk and few layer flakes using polarized Raman\nspectroscopy and density functional theory (DFT) analysis to determine the\nmaterial's vibrational modes, as well as their symmetrical representations and\natomic displacements. We experimentally resolved 12 phonon modes, 5 of which\nare A1g modes while the remaining 7 are Eg modes, which is in strong agreement\nwith our DFT calculation. Layer-dependent results suggest that the Raman peak\npositions are mostly insensitive to changes in layer thickness, while peak\nintensity and FWHM are affected. Raman measurements as a function of excitation\nwavelength (473-785 nm) show a significant increase of the peak intensities\nwhen using a 473 nm excitation source, suggesting a near resonant condition.\nTemperature-dependent Raman experiments carried out above and below the\ntransition temperature did not show any change in the symmetries of the phonon\nmodes, suggesting that the structural phase transition is likely from the high\ntemperature P3m1 phase to the low-temperature R3m phase. Magneto-Raman\nmeasurements carried out at 140 and 2 K between -2 to 2 T show that the Raman\nmodes are not magnetically coupled. Overall, our study presented here\nsignificantly advances the fundamental understanding of layered Nb3Cl8 material\nwhich can be further exploited for future applications."
    },
    {
        "anchor": "Anomalous Hall effect in anatase Ti1-xCoxO2 at low temperature regime: Anomalous Hall effect (AHE) of a ferromagnetic semiconductor anatase \\cotio\nthin film is studied from 10K to 300K. Magnetic field dependence of anomalous\nHall resistance is coincident with that of magnetization, while the anomalous\nHall resistance decreases at low temperature in spite of nearly\ntemperature-independent magnetization. Anomalous Hall conductivity sigma_AHE is\nfound to be proportional to the square of Hall mobility, suggesting that charge\nscattering strongly affects the AHE in this system. The anatase Ti1-xCoxO2 also\nfollows a scaling relationship to conductivity sigma_xx as sigma_AHE ~\nsigma_xx^1.6, which was observed for another polymorph rutile Ti1-xCoxO2,\nsuggesting an identical mechanism of their AHE.",
        "positive": "Investigation of acceptor levels and hole scattering mechanisms in\n  p-gallium selenide by means of transport measurements under pressure: The effect of pressure on acceptor levels and hole scattering mechanisms in\np-GaSe is investigated through Hall effect and resistivity measurements under\nquasi-hydrostatic conditions up to 4 GPa. The pressure dependence of the hole\nconcentration is interpreted through a carrier statistics equation with a\nsingle (nitrogen) or double (tin) acceptor whose ionization energies decrease\nunder pressure due to the dielectric constant increase. The pressure effect on\nthe hole mobility is also accounted for by considering the pressure\ndependencies of both the phonon frequencies and the hole-phonon coupling\nconstants involved in the scattering rates."
    },
    {
        "anchor": "Cracks and Crazes: On calculating the macroscopic fracture energy of\n  glassy polymers from molecular simulations: We combine molecular dynamics simulations of deformations at the submicron\nscale with a continuum fracture mechanics calculation for the onset of crack\npropagation to predict the macroscopic fracture toughness of amorphous glassy\npolymers. Key ingredients in this multiscale approach are the elastic\nproperties of polymer crazes and the stress at which craze fibrils fail through\nchain pullout or scission. Our results are in quantitative agreement with\ndimensionless ratios that describe experimental polymers and their variation\nwith temperature, polymer length and polymer rigidity.",
        "positive": "Engineering Diffusivity and Operating Voltage in Lithium Iron Phosphate\n  through Transition Metal Doping: Density functional calculations are carried out to understand and tailor the\nelectrochemical profile diffusivity, band gap and open circuit voltage of\ntransition metal doped olivine phosphate $LiFe_{1-x}M_{x}PO_{4}$ (M = V, Cr,\nMn, Co and Ni). Diffusion and hence the ionic conductivity is studied by\ncalculating the activation barrier, $V_{act}$, experienced by the diffusing\n$Li^{+}$ ion. We show that the effect of dopants on diffusion is both site\ndependent and short ranged and thereby it paves ways for microscopic control of\nionic conductivity via selective dopants in this olivine phosphates. Dopants\nwith lower valence electrons (LVE) compared to Fe repel the $Li^{+}$ ion to\nfacilitate its outward diffusion, whereas higher valence electron (HVE) dopants\nattracts the $Li^{+}$ ion to facilitate the inward diffusion. From the\nelectronic structure calculation we establish that irrespective of the dopant\nM, except Mn, the band gap is reduced since the M-$d$ states always lie within\nthe pure band gap. Atomically localized $d$ states of HVE dopants lie above the\nFermi energy and that of LVE lie below it. Half-filled Mn-$d$ states undergo\nlarge spin-exchange split to bury the dopant states in valence and conduction\nbands of the pristine system and in turn the band gap remains unchanged in\n$LiFe_{1-x}Mn_{x}PO_{4}$. Baring Mn, the open circuit voltage increases with\nHVE dopants and decreases with LVE dopants."
    },
    {
        "anchor": "Surface structures of graphene covered Cu (103): We studied the surface structures of chemical vapor deposited (CVD) graphene\non Cu(103). The graphene covered Cu surface had (103) facets parallel to the\nCu[010] direction, on which triangular patterns were formed. In contrast, the\nbare Cu surface showed no facets. Post-growth thermal annealing in an\nultra-high vacuum induced surface changes on the Cu(103) facets. The\nreorganization of the Cu surface by the post-growth thermal annealing led to a\nchange in the lattice strain and hole doping level of the CVD-grown graphene.",
        "positive": "Single-walled TiO2 Nanotubes: Enhanced Carrier-transport Properties by\n  TiCl4-Treatment: In the present work we report significant enhancement of the\nphotoelectrochemical properties of self-organized TiO2 nanotubes by a combined\nde-coring of classic nanotubes followed by an appropiate TiCl4-treatment. We\nshow that, except for the expected particle decoration, a key effect of the\nTiCl4 treatment is that the electron transport characteristics in TiO2\nnanotubes can be drastically improved, e.g. we observe an enhancement of up to\n70 % in electron transport times."
    },
    {
        "anchor": "Spin-Glass Model for Inverse Freezing: We analyze the Blume-Emery-Griffiths model with disordered magnetic\ninteraction displaying the inverse freezing phenomenon. The behaviour of this\nspin-1 model in crystal field is studied throughout the phase diagram and the\ntransition and spinodal lines for the model are computed using the Full Replica\nSymmetry Breaking Ansatz that always yelds a thermodynamically stable phase. We\ncompare the results both with the quenched disordered model with Ising spins on\nlattice gas - where no reentrance takes place - and with the model with\ngeneralized spin variables recently introduced by Schupper and Shnerb [Phys.\nRev. Lett. 93, 037202 (2004)]. The simplest version of all these models, known\nas Ghatak-Sherrington model, turns out to hold all the general features\ncharacterizing an inverse transition to an amorphous phase, including the right\nthermodynamic behavior.",
        "positive": "First-principles study of luminescence in hexagonal boron nitride single\n  layer: exciton-phonon coupling and the role of substrate: Hexagonal boron nitride (hBN) is a wide band gap material with both strong\nexcitonic light emission in the ultraviolet and strong exciton-phonon coupling.\nLuminescence experiments performed on the recently synthesized monolayer form\n(m-hBN) present emission spectra that differ from one another, with some\nsuggesting a coexistence between phonon-assisted and direct emission channels.\nMotivated by these results, we investigated the optical response of (m-hBN)\nusing a new \\textit{ab initio} approach that takes into account the effects of\natomic vibrations on the luminescence spectra. We construct the dynamical\nexciton-phonon self-energy, then use it to perturbatively correct the optical\nresponse functions and test this approach on bulk hBN as a benchmark. Within\nour approach we are able to estimate the renormalisation of the direct peak\ninduced by phonon-assisted transitions, and this allows us to accurately\ndescribe spectra where both processes are present. We found that the emission\nsignal of m-hBN is strongly dependent on its interaction with the substrate,\nwhich changes its nature from direct to indirect material and modifies the\nscreening felt by the electrons. We attribute the m-hBN emission signal to the\nbright direct excitons and consider the likelihood of phonon replicas\nappearing."
    },
    {
        "anchor": "Self - Organized Si Dots On Ge Substrates: The epitaxial growth conditions for silicon on germanium substrates were\ninvestigated as a function of growth temperature and monolayer coverage. Island\nformation was observed for the hole studied temperature range, although strong\nalloying with the substrate occurred for the highest temperatures. Carbon\npre-deposition offers suitable nucleation centers for the Si island and\nreduction of alloying. pre-structured Ge substrates were prepared to enhance\nislanding and to achieve ordering.",
        "positive": "Precessing vortices and antivortices in ferromagnetic elements: A micromagnetic numerical study of the precessional motion of the vortex and\nantivortex states in soft ferromagnetic circular nanodots is presented using\nLandau-Lifshitz-Gilbert dynamics. For sufficiently small dot thickness and\ndiameter, the vortex state is metastable and spirals toward the center of the\ndot when its initial displacement is smaller than a critical value. Otherwise,\nthe vortex spirals away from the center and eventually exits the dot which\nremains in a state of in-plane magnetization (ground state). In contrast, the\nantivortex is always unstable and performs damped precession resulting in\nannihilation at the dot circumference. The vortex and antivortex frequencies of\nprecession are compared with the response expected on the basis of Thiele's\ntheory of collective coordinates. We also calculate the vortex restoring force\nwith an explicit account of the magnetostatic and exchange interaction on the\nbasis of the 'rigid' vortex and 'two-vortices side charges free' models and\nshow that neither model explains the vortex translation mode eigenfrequency for\nnanodots of sufficiently small size."
    },
    {
        "anchor": "Hybrid photovoltaic and electron-tunneling converters: Photon impingement is capable of liberating electrons in semiconductors. When\nthe electron transport is primarily governed by temperature gradients, high\nirreversibilities will result, thus lowering converters' efficiencies. A\nfundamental study in the absence of photovoltaics\\cite{1} has achieved the\nreduction of these irreversibilities by considering entropy changes due to\nelectron flows. Here we present an unreported mechanism that integrates\nphotovoltaic conversion and electron tunneling. Photon-excited electrons that\noccupy energy levels beyond windowed limits are first imprisoned inside the\ncathode, then given opportunities to rapidly re-thermalize, and eventually\nallowed to enter the tunnel. Energies wasted by both the irreversibility and\nthe recombination are minimized with respect to the transmission energy and the\ntransmission window that characterize the tunnel. Upon application of this\nmechanism to high-concentration solar cells, the proposed hybrid model\noutperforms others. It further provides a guide for elevating efficiencies in\nfuture photon-to-electron converters typified by third-generation photovoltaic\nsystems.",
        "positive": "Properties of dislocation lines in crystals with strong atomic-scale\n  disorder: We use a discrete dislocation dynamics (DDD) approach to study the motion of\na dislocation under strong stochastic forces that may cause bending and\nroughening of the dislocation line on scales that are comparable to the\ndislocation core radius. In such situations, which may be relevant in high\nentropy alloys (HEA) exhibiting strong atomic scale disorder, standard scaling\narguments based upon a line tension approximation may be no longer adequate and\ncorrections to scaling need to be considered. We first study the wandering of\nthe dislocation under thermal Langevin forces. This leads to a linear\nstochastic differential equation which can be exactly solved. From the Fourier\nmodes of the thermalized dislocation line we can directly deduce the scale\ndependent effective line tension. We then use this information to investigate\nthe wandering of a dislocation in a crystal with spatial, time-independent\n('quenched') disorder. We establish the pinning length and show how this length\ncan be used as a predictor of the flow stress. Implications for the\ndetermination of flow stresses in HEA from molecular dynamics simulations are\ndiscussed."
    },
    {
        "anchor": "Cell dynamics modeling of phase transformation and metastable phase\n  formation: The phase transition kinetics in three phase systems was investigated using\nthe numerically efficient cell dynamics method. A phasefield model with a\nsimple analytical free energy and single order parameter was used to study the\nkinetics and the thermodynamics of a three-phase system. This free energy is\nable to achieve three phases coexistence, which for simplicity we call \\alpha,\n\\beta and \\gamma phases. Our study focused on the kinetics of phase transition\nrather than the nucleation of a seed of a new phase that was introduced into\nthe matrix of the old phase when the relative stability of the three phases\nwere changed. We found dynamical as well as kinetically arrested static\nscenarios in the appearance of the macroscopic metastable phase. A few other\ninteresting scenarios of the kinetics of phase transition in this three-phase\nsystem will be demonstrated and discussed.",
        "positive": "Impurity-vacancy complexes and ferromagnetism in doped sesquioxides: Based on hybrid density-functional calculations, we propose that\nferromagnetism in the prototypical bixbyite sesquioxide In$_2$O$_3$ doped with\nCr is due to Cr-oxygen vacancy complexes, while isolated Cr cannot support\ncarrier-mediated magnetic coupling. Our proposal is consistent with\nexperimental facts such as the onset of ferromagnetism in O-lean conditions\nonly, the low or vanishing net moment in unintentionally doped material, and\nits increase upon intentional doping."
    },
    {
        "anchor": "Symmetry-based computational search for novel binary and ternary 2D\n  materials: We present a symmetry-based exhaustive approach to explore the structural and\ncompositional richness of two-dimensional materials. We use a ``combinatorial\nengine'' that constructs potential compounds by occupying all possible Wyckoff\npositions for a certain space group with combinations of chemical elements.\nThese combinations are restricted by imposing charge neutrality and the Pauling\ntest for electronegativities. The structures are then pre-optimized with a\nspecially crafted universal neural-network force-field, before a final step of\ngeometry optimization using density-functional theory is performed. In this way\nwe unveil an unprecedented variety of two-dimensional materials, covering the\nwhole periodic table in more than 30 different stoichiometries of form\nA$_n$B$_m$ or A$_n$B$_m$C$_k$. Among the found structures we find examples that\ncan be built by decorating nearly all Platonic and Archimedean tesselations as\nwell as their dual Laves or Catalan tilings. We also obtain a rich, and\nunexpected, polymorphism for some specific compounds. We further accelerate the\nexploration of the chemical space of two-dimensional materials by employing\nmachine-learning-accelerated prototype search, based on the structural types\ndiscovered in the exhaustive search. In total, we obtain around 6500 compounds,\nnot present in previous available databases of 2D materials, with an energy of\nless than 250~meV/atom above the convex hull of thermodynamic stability.",
        "positive": "Magnetic properties of pseudomorphic epitaxial films of\n  Pr_{0.7}Ca_{0.3}MnO_3 under different biaxial tensile stresses: In order to analyse the effect of strain on the magnetic properties of\nnarrow-band manganites, the temperature and field dependent susceptibilities of\nabout 8.5 nm thick epitaxial Pr0.7Ca0.3MnO3 films, respectively grown on (001)\nand (110) SrTiO3 substrates, have been compared. For ultrathin samples grown on\n(001) SrTiO3, a bulk-like cluster-glass magnetic behaviour is found, indicative\nof the possible coexistence of antiferromagnetic and ferromagnetic phases. On\nthe contrary, ultrathin films grown on (110) substrates show a robust\nferromagnetism, with a strong spontaneous magnetization of about 3.4 mB /Mn\natom along the easy axis. On the base of high resolution reciprocal space\nmapping analyses performed by x-ray diffraction, the different behaviours are\ndiscussed in terms of the crystallographic constraints imposed by the epitaxy\nof Pr0.7Ca0.3MnO3 on SrTiO3. We suggest that for growth on (110) SrTiO3, the\ntensile strain on the film c-axis, lying within the substrate plane, favours\nthe ferromagnetic phase, possibly by allowing a mixed occupancy and\nhybridization of both in-plane and out-of-plane eg orbitals. Our data allow to\nshed some physics of inhomogeneous states in manganites and on the nature of\ntheir ferromagnetic insulating state."
    },
    {
        "anchor": "Measurements of Cylindrical Ice Crystal Growth Limited by Combined\n  Particle and Heat Diffusion: We present measurements of the growth of long columnar ice crystals from\nwater vapor over a broad range of temperatures and supersaturation levels in\nair. Starting with thin, c-axis ice needle crystals, we observed their\nsubsequent growth behavior in a vapor diffusion chamber, extracting the initial\nradial growth velocities of the needles under controlled conditions.\nApproximating the hexagonal needle crystals as infinitely long cylinders, we\ncreated an analytical growth model that includes effects from particle\ndiffusion of water molecules through the surrounding air along with the\ndiffusion of heat generated by solidification. With only minimal adjustment of\nmodel parameters, we obtained excellent agreement with our experimental data.\nTo our knowledge, this is the first time that the combined effects from\nparticle and heat diffusion have been measured in ice growth from water vapor.\nThis analysis further provides an accurate method for calibration of the\nwater-vapor supersaturation levels in experimental growth chambers.",
        "positive": "Vapor phase epitaxy of antimonene-like nanocrystals on germanium by an\n  MOCVD process: Synthetic two-dimensional (2D) mono-elemental crystals, namely X-enes, have\nrecently emerged as a new frontier for atomically thin nanomaterials with\non-demand properties. Among X-enes, antimonene, the \\b{eta}-phase allotrope of\nantimony, is formed by atoms arranged in buckled hexagonal rings bearing a\ncomparatively higher environmental stability with respect to other players of\nthis kind. However, the exploitation of monolayer or few-layer antimonene and\nother 2D materials in novel opto-electronic devices is still hurdled by the\nlack of scalable processes. Here, we demonstrated the viability of a bottom-up\nprocess for the epitaxial growth of antimonene-like nanocrystals (ANCs), based\non a Metal-Organic Chemical Vapor Deposition (MOCVD) process, assisted by gold\nnanoparticles (Au NPs) on commensurate (111)-terminated Ge surfaces. The growth\nmechanism was investigated by large- and local-area microstructural analysis,\nrevealing that the etching of germanium, catalyzed by the Au NPs, led to the\nANCs growth on the exposed Ge (111) planes. As a supportive picture, ab-initio\ncalculations rationalized this epitaxial relationship in terms of compressively\nstrained \\b{eta}-phase ANCs. Our process could pave the way to the realization\nof large-area antimonene layers by a deposition process compatible with the\ncurrent semiconductor manufacturing technology."
    },
    {
        "anchor": "Hydrogenation of Penta-Graphene Leads to Unexpected Large Improvement in\n  Thermal Conductivity: Penta-graphene (PG) has been identified as a novel 2D material with an\nintrinsic bandgap, which makes it especially promising for electronics\napplications. In this work, we use first-principles lattice dynamics and\niterative solution of the phonon Boltzmann transport equation (BTE) to\ndetermine the thermal conductivity of PG and its more stable derivative -\nhydrogenated penta-graphene (HPG). As a comparison, we also studied the effect\nof hydrogenation on graphene thermal conductivity. In contrast to hydrogenation\nof graphene, which leads to a dramatic decrease in thermal conductivity (from\n3590 to 1328 W/mK - a 63% reduction), HPG shows a notable increase in thermal\nconductivity (615 W/mK), which is 76% higher than that of PG (350 W/mK). The\nhigh thermal conductivity of HPG makes it more thermally conductive than most\nother semi-conducting 2D materials, such as the transition metal chalcogenides.\nOur detailed analyses show that the primary reason for the counter-intuitive\nhydrogenation-induced thermal conductivity enhancement is the weaker bond\nanharmonicity in HPG than PG. This leads to weaker phonon scattering after\nhydrogenation, despite the increase in the phonon scattering phase space. The\nhigh thermal conductivity of HPG may inspire intensive research around HPG and\nother derivatives of PG as potential materials for future nanoelectronic\ndevices. The fundamental physics understood from this study may open up a new\nstrategy to engineer thermal transport properties of other 2D materials by\ncontrolling bond anharmonicity via functionalization.",
        "positive": "Single-pass STEM-EMCD on a zone axis using a patterned aperture:\n  progress in experimental and data treatment methods: Measuring magnetic moments in ferromagnetic materials with atomic column\nresolution is theoretically possible using the electron magnetic circular\ndichroism (EMCD) technique in a (scanning) transmission electron microscope\n((S)TEM). However, experimental and data processing hurdles currently hamper\nthe realization of this goal. Experimentally, the sample must be tilted to a\nzone-axis orientation, yielding a complex distribution of magnetic scattering\nintensity, and the same sample region must be scanned multiple times with\nsub-atomic spatial registration necessary at each pass. Furthermore, the weak\nnature of the EMCD signal requires advanced data processing techniques to\nreliably detect and quantify the result. In this manuscript, we detail our\nexperimental and data processing progress towards achieving single-pass\nzone-axis EMCD using a patterned aperture. First, we provide a comprehensive\ndata acquisition and analysis strategy for this and other EMCD experiments that\nshould scale down to atomic resolution experiments. Second, we demonstrate\nthat, at low spatial resolution, promising EMCD candidate signals can be\nextracted, and that these are sensitive to both crystallographic orientation\nand momentum transfer."
    },
    {
        "anchor": "A method to restore the intrinsic dielectric functions of 2D materials\n  in periodic calculations and its applications to the dielectric and optical\n  properties of ultrathin h-BN and MoS2: Previous calculations of the dielectric and optical properties of 2D\nmaterials often overlooked or circumvented the influence of vacuum spacing\nintroduced in periodic calculations, which gave rise to mispredictions of the\nintrinsic properties of 2D materials or merely qualitative results. We first\nelucidate the relationship between the vacuum spacing and the dielectric and\noptical properties of 2D materials in periodic calculations, and then bring\nforward an effective method to accurately predict the dielectric and optical\nproperties of 2D materials by restoring the intrinsic dielectric functions of\n2D materials independent of the additional vacuum spacing. As examples, the\nintrinsic dielectric and optical properties of ultrathin h-BN and MoS2 from\nmonolayer to pentalayer, including dielectric functions, optical absorption\ncoefficients, refraction indexes, reflectivities, extinction coefficients, and\nenergy loss functions, have been calculated by our method. Our calculations\nreveal that the out-of-plane optical dielectric constants, static refraction\nindexes, and static reflectivities of 2D h-BN and MoS2 increase as the number\nof layers increases, while the in-plane counterparts remain unchanged.\nExcitonic frequency-dependent optical properties of h-BN and MoS2 from\nmonolayer to bulk are also calculated by solving the Bethe-Salpeter equation\nand show strong anisotropy. In better agreement with experimental results than\nprevious calculations, the presented method demonstrates enormous potential to\ninvestigate the dielectric and optical properties of other 2D materials\nextensively and quantitively.",
        "positive": "Design and properties of low energy x-ray transmission windows based on\n  graphenic carbon: X-ray transmission windows for the low energy range, especially between 0.1\nkeV and 1 keV have been designed and fabricated based on graphenic carbon (GC)\nwith an integrated silicon frame. A hexagonal and a bar grid support structure\ndesign have been evaluated. The bar grid design allows to substitute\npolymer-based windows with the advantages of higher transmission, better\nrejection of visible light and vacuum operability of the encapsulated silicon\ndrift detectors (SDD). In addition, the high mechanical resilience of graphenic\ncarbon is demonstrated by pressure cycle tests, yielding over 10 million cycles\nwithout damage. The data are complemented by bulge tests to determine a Young`s\nmodulus for graphenic carbon of approximately 130 GPa. Additional\nfinite-element simulation and Raman studies reveal that the mechanical stress\nis not homogeneously distributed, but reaches a maximum near the anchoring\npoints of the free standing graphenic carbon membrane."
    },
    {
        "anchor": "Signatures of nonadiabatic O2 dissociation at Al(111): First-principles\n  fewest-switches study: Recently, spin selection rules have been invoked to explain the discrepancy\nbetween measured and calculated adsorption probabilities of molecular oxygen\nreacting with Al(111). In this work, we inspect the impact of nonadiabatic spin\ntransitions on the dynamics of this system from first principles. For this\npurpose the motion on two distinct potential-energy surfaces associated to\ndifferent spin configurations and possible transitions between them are\ninspected by means of the Fewest Switches algorithm. Within this framework we\nespecially focus on the influence of such spin transitions on observables\naccessible to molecular beam experiments. On this basis we suggest experimental\nsetups that can validate the occurrence of such transitions and discuss their\nfeasibility.",
        "positive": "Vector Chirality $\u03ba$ Driven Topological Phase Transition and the\n  Associated Anomalous Hall Conductivity Tuning in a Non-Collinear\n  Antiferromagnet: Based on the first-principles electronic structure calculations and\nsubsequent symmetry adapted effective low-energy $\\textbf{k.p}$ theory, we show\nthe switching of the vector chirality, $\\kappa$, in a noncollinear\nantiferromagnet (AFM), Mn$_3$Sn, as an unconventional route to topological\nphase transition from a nodal-ring to a Weyl point semimetal. Specifically, we\nfind that the switching of $\\kappa$ leads to gaping out an elliptic nodal-ring\neverywhere at the Fermi-level except for a pair of points on the ring. As a\nconsequence, the topological phase transition switches the anomalous Hall\nconductivity (AHC) from zero to a giant value. Furthermore, we theoretically\ndemonstrate how the controlled manipulation of the chiral AFM order keeping\n$\\kappa$ unaltered favors unusual rotation of Weyl-points on the ring. This in\nturn enables us to tune in-plane components of the AHC by a collective uniform\nrotations of spins in the AFM unit cell."
    },
    {
        "anchor": "Noble gas films on a decagonal AlNiCo quasicrystal: Thermodynamic properties of Ne, Ar, Kr, and Xe adsorbed on an Al-Ni-Co\nquasicrystalline surface (QC) are studied with Grand Canonical Monte Carlo by\nemploying Lennard-Jones interactions with parameter values derived from\nexperiments and traditional combining rules. In all the gas/QC systems, a\nlayer-by-layer film growth is observed at low temperature. The monolayers have\nregular epitaxial fivefold arrangements which evolve toward sixfold\nclose-packed structures as the pressure is increased. The final states can\ncontain either considerable or negligible amounts of defects. In the latter\ncase, there occurs a structural transition from five to sixfold symmetry which\ncan be described by introducing an order parameter, whose evolution\ncharacterizes the transition to be continuous or discontinuous as in the case\nof Xe/QC (first-order transition with associated latent heat). By simulating\nfictitious noble gases, we find that the existence of the transition is\ncorrelated with the size mismatch between adsorbate and substrate's\ncharacteristic lengths. A simple rule is proposed to predict the phenomenon.",
        "positive": "Comments on 'Revisiting building block ordering of long-period stacking\n  ordered structures in Mg-Y-Al alloys': In a recent paper, Zhang et al. [Acta Materialia 152 (2018) 96] studied the\nin-plane ordering of the long-period stacking ordered (LPSO) structure in\nMg-Al-Y alloys. In addition to the well-known L12 type building cluster, they\nproposed three new types of metastable building clusters. However, we will show\nthat these new types of building clusters are caused by the superimposition of\nL12 type clusters located in different domains. In addition, the experimental\nevidence for domain structures in a similar alloy system Mg-Al-Gd is provided."
    },
    {
        "anchor": "Temperature dependence of the anharmonic decay of optical phonons in\n  carbon nanotubes and graphite: We report on the temperature dependence of the anharmonic decay rate of\nzone-center (G mode) optical phonons in both single-walled carbon nanotubes and\ngraphite. The measurements are performed using a pump-probe Raman scattering\nscheme with femtosecond laser pulses. For nanotubes, measured over a\ntemperature range of 6 K-700 K, we observe little temperature dependence of the\ndecay rate below room temperature. Above 300 K, the decay rate increases from\n0.8 to 1.7 ps-1. The decay rates observed for graphite range from 0.5 to 0.8\nps-1 for temperatures from 300 K-700 K. We compare the behavior observed in\ncarbon nanotubes and graphite and discuss the implications of our results for\nthe mechanism of the anharmonic decay of optical phonons in both systems.",
        "positive": "Scaling of Fracture Strength in Disordered Quasi-Brittle Materials: This paper presents two main results. The first result indicates that in\nmaterials with broadly distributed microscopic heterogeneities, the fracture\nstrength distribution corresponding to the peak load of the material response\ndoes not follow the commonly used Weibull and (modified) Gumbel distributions.\nInstead, a {\\it lognormal} distribution describes more adequately the fracture\nstrengths corresponding to the peak load of the response. Lognormal\ndistribution arises naturally as a consequence of multiplicative nature of\nlarge number of random distributions representing the stress scale factors\nnecessary to break the subsequent \"primary\" bond (by definition, an increase in\napplied stress is required to break a \"primary\" bond) leading up to the peak\nload. Numerical simulations based on two-dimensional triangular and diamond\nlattice topologies with increasing system sizes substantiate that a {\\it\nlognormal} distribution represents an excellent fit for the fracture strength\ndistribution at the peak load. The second significant result of the present\nstudy is that, in materials with broadly distributed microscopic\nheterogeneities, the mean fracture strength of the lattice system behaves as\n$\\mu_f = \\frac{\\mu_f^\\star}{(Log L)^\\psi} + \\frac{c}{L}$, and scales as $\\mu_f\n\\approx \\frac{1}{(Log L)^\\psi}$ as the lattice system size, $L$, approaches\ninfinity."
    },
    {
        "anchor": "Electron-Phonon Coupling, Thermal Expansion Coefficient, Resonance\n  Effect and Phonon Dynamics in High Quality CVD Grown Mono and Bilayer MoSe2: Probing phonons, quasi-particle excitations and their coupling has enriched\nour understanding of these 2D materials and proved to be crucial for developing\ntheir potential applications. Here, we report comprehensive temperature, 4-330\nK, and polarization-dependent Raman measurements on mono and bilayer MoSe2.\nPhonon's modes up to fourth-order are observed including forbidden Raman and IR\nmodes, understood considering Frohlich mechanism of exciton-phonon coupling.\nMost notably, anomalous variations in the phonon linewidths with temperature\npointed at the significant role of electron-phonon coupling in these systems,\nespecially for the out-of-plane (A1g) and shear mode (E22g), which is found to\nbe more prominent in the narrow-gaped bilayer than the large gapped monolayer.\nVia polarization-dependent measurements, we deciphered the ambiguity in\nsymmetry assignments, especially to the peaks around ~ 170 cm-1 and ~ 350 cm-1.\nTemperature-dependent thermal expansion coefficient, an important parameter for\nthe device performance, is carefully extracted for both mono and bilayer by\nmonitoring the temperature-dependence of the real-part of the phonon\nself-energy parameter. Our temperature-dependent in-depth Raman studies provide\na pave for uncovering the deeper role of phonons in these 2D layered materials\nfrom a fundamental as well as application point of view.",
        "positive": "Spatially correlated incommensurate lattice modulations in an atomically\n  thin high-temperature Bi_{2.1}Sr_{1.9}CaCu_{2.0}O_{8+\u03b4}\n  superconductors: Strong variations in superconducting critical temperatures in different\nfamilies of the cuprate perovskites, even with similar hole doping in their\ncopper-oxygen planes, suggest the importance of lattice modulation effects. The\none-dimensional incommensurate lattice modulation (ILM) of\nBi_2Sr_2CaCu_2O_{8+y}, with the average atomic positions perturbed beyond the\nunit cell, offers an ideal test ground for studying the interplay between\nsuperconductivity and the long-range incommensurate lattice fluctuations. Here\nwe report Scanning nano X-ray Diffraction (SnXRD) imaging of incommensurate\nlattice modulations in Bi_{2.1}Sr_{1.9}CaCu_{2.0}O_{8+{\\delta}} Van der Waals\nheterostructures of thicknesses down to two-unit cells. Using SnXRD, we probe\nthat the long-range and short-range incommensurate lattice modulations in bulk\nsample surface with spatial resolution below 100 nm. We find that puddle-like\ndomains of ILM of size uniformly evolving with dimensionality. In the 2-unit\ncell thin sample, it is observed that the wavevectors of the long- and\nshort-range orders become anti-correlated with emerging spatial patterns having\na directional gradient. The emerging patterns, originated by tiny tuning of\nlattice strain, induce static mesoscopic charge density waves. Our findings\nthus demonstrate that the strain can be used to tune and control the\nelectromagnetic properties of two-dimensional high-temperature superconductors."
    },
    {
        "anchor": "Magnetic control of Goos-Hanchen shifts in a yttrium-iron-garnet film: We investigate the Goos-Hanchen (G-H) shifts reflected and transmitted by a\nyttrium-iron-garnet (YIG) film for both normal and oblique incidence. It is\nfound that the nonreciprocity effect of the MO material does not only result in\na nonvanishing reflected shift at normal incidence, but also leads to a\nslab-thickness-independent term which breaks the symmetry between the reflected\nand transmitted shifts at oblique incidence. The asymptotic behaviors of the\nnormal-incidence reflected shift are obtained in the vicinity of two\ncharacteristic frequencies corresponding to a minimum reflectivity and a total\nreflection, respectively. Moreover, the coexistence of two types of\nnegative-reflected-shift (NRS) at oblique incidence is discussed. We show that\nthe reversal of the shifts from positive to negative values can be realized by\ntuning the magnitude of applied magnetic field, the frequency of incident wave\nand the slab thickness as well as the incident angle. In addition, we further\ninvestigate two special cases for practical purposes: the reflected shift with\na total reflection and the transmitted shift with a total transmission.\nNumerical simulations are also performed to verify our analytical results.",
        "positive": "Exploring the transfer of plasticity across Laves phase interfaces in a\n  dual phase magnesium alloy: The mechanical behaviour of Mg-Al alloys can be largely improved by the\nformation of an intermetallic Laves phase skeleton, in particular the creep\nstrength. Recent nanomechanical studies revealed plasticity by dislocation\nglide in the (Mg,Al)$_2$Ca Laves phase, even at room temperature. As\nstrengthening skeleton, this phase remains, however, brittle at low\ntemperature. In this work, we present experimental evidence of slip transfer\nfrom the Mg matrix to the (Mg,Al)$_2$Ca skeleton at room temperature and\nexplore associated mechanisms by means of atomistic simulations. We identify\ntwo possible mechanisms for transferring Mg basal slip into Laves phases\ndepending on the crystallographic orientation: a direct and an indirect slip\ntransfer triggered by full and partial dislocations, respectively. Our\nexperimental and numerical observations also highlight the importance of\ninterfacial sliding that can prevent the transfer of the plasticity from one\nphase to the other."
    },
    {
        "anchor": "Weyl Node and Spin Texture in Trigonal Tellurium and Selenium: We study Weyl nodes in materials with broken inversion symmetry. We find\nbased on first-principles calculations that trigonal Te and Se have multiple\nWeyl nodes near the Fermi level. The conduction bands have a spin splitting\nsimilar to the Rashba splitting around the H points, but unlike the Rashba\nsplitting the spin directions are radial, forming a hedgehog spin texture\naround the H points, with a nonzero Pontryagin index for each spin-split\nconduction band. The Weyl semimetal phase, which has never been observed in\nreal materials without inversion symmetry, is realized under pressure. The\nevolution of the spin texture by varying the pressure can be explained by the\nevolution of the Weyl nodes in k space.",
        "positive": "On the use of Solomon echoes in 27Al NMR studies of complex aluminium\n  hydrides: The quadrupole coupling constant $C_Q$ and the asymmetry parameter $\\eta$\nhave been determined for two complex aluminium hydrides from $^{27}$Al NMR\nspectra recorded for stationary samples by using the Solomon echo sequence. The\nthus obtained data for KAlH4 ($C_Q=(1.30\\pm0.02)$ MHz, $\\eta=(0.64\\pm0.02)$)\nand NaAlH4 ($C_Q=(3.11\\pm0.02)$ MHz, $\\eta<0.01$) agree very well with data\npreviously determined from MAS NMR spectra. The accuracy with which these\nparameters can be determined from static spectra turned out to be at least as\ngood as via the MAS approach. The experimentally determined parameters\n($\\delta_{iso}$, $C_Q$ and $\\eta$) are compared with those obtained from\nDFT-GIPAW (density functional theory - gauge-including projected augmented\nwave) calculations. Except for the quadrupole coupling constant for KAlH4,\nwhich is overestimated in the GIPAW calculations by about 30%, the agreement is\nexcellent. Advantages of the application of the Solomon echo sequence for the\nmeasurement of less stable materials or for in-situ studies are discussed."
    },
    {
        "anchor": "Materials Contrast in Piezoresponse Force Microscopy: Piezoresponse Force Microscopy contrast in transversally isotropic material\ncorresponding to the case of c+ - c- domains in tetragonal ferroelectrics is\nanalyzed using Green's function theory by Felten et al. [J. Appl. Phys. 96, 563\n(2004)]. A simplified expression for PFM signal as a linear combination of\nrelevant piezoelectric constant are obtained. This analysis is extended to\npiezoelectric material of arbitrary symmetry with weak elastic and dielectric\nanisotropies. This result provides a framework for interpretation of PFM\nsignals for systems with unknown or poorly known local elastic and dielectric\nproperties, including nanocrystalline materials, ferroelectric polymers, and\nbiopolymers.",
        "positive": "Geometrical and electronic structures of the (5, 3) single-walled gold\n  nanotube from first-principles calculations: The geometrical and electronic structures of the 4 {\\AA} diameter perfect and\ndeformed (5, 3) single-walled gold nanotube (SWGT) have been studied based upon\nthe density-functional theory in the local-density approximation (LDA). The\ncalculated relaxed geometries show clearly significant deviations from those of\nthe ideally rolled triangular gold sheet. It is found that the different\nstrains have different effects on the electronic structures and density of\nstates of the SWGTs. And the small shear strain can reduce the binding energy\nper gold atom of the deformed SWGT, which is consistent with the experimentally\nobserved result. Finally, we found the finite SWGT can show the\nmetal-semiconductor transition."
    },
    {
        "anchor": "Evidence of Spin-Glass state in Molecular Exchange-Bias System: In conventional exchange-bias system comprising of a bilayer film of\nferromagnet (FM) and antiferromagnet (AFM), investigating the role of\nspin-disorder and spin-frustration inside the AFM and at the interface has been\ncrucial in understanding the fundamental mechanism controlling the\nexchange-bias -- an effect that leads to a horizontal shift in the\nmagnetization hysteresis response of the FM. Similarly, in the recently\nreported monolayer molecular exchange-bias effect requiring no AFM layer,\nprobing magnetic-disorder at the FM/molecule interface or inside the FM layer\ncan provide new insights into the origin of molecular exchange-bias and the\nassociated physics. In this article, by cooling the Fe/metal-phthalocyanine\ndevices in oscillating magnetic field, we demonstrate a characteristic\ntemperature dependent response of exchange-bias shift and ferromagnet\ncoercivity that is supportive of a spin-glass behavior. Here, the origin of\nspin-glass is attributed to the spin frustration created in the magnetic\nstructure of the Fe layer, which was absent in our reference-Fe studies. These\nresults highlight the strong influence of FM/molecule interface pi-d\nhybridization on the magnetic exchange interactions extending deeper into the\nFM layer.",
        "positive": "Unravelling the atomic and electronic structure of nanocrystals on\n  superconducting Nb(110): Impact of the oxygen monolayer: The Niobium surface is almost always covered by a native oxide layer which\ngreatly influences the performance of superconducting devices. Here we\ninvestigate the highly stable Niobium oxide overlayer of Nb(110), which is\ncharacterised by its distinctive nanocrystal structure as observed by scanning\ntunnelling microscopy (STM). Our ab-initio density functional theory (DFT)\ncalculations show that a subtle reconstruction in the surface Niobium atoms\ngives rise to rows of 4-fold coordinated oxygen separated by regions of 3-fold\ncoordinated oxygen. The 4-fold oxygen rows are determined to be the source of\nthe nanocrystal pattern observed in STM, and the two chemical states of oxygen\nobserved in core-level X-ray photoelectron spectroscopy (XPS) are ascribed to\nthe 3-fold and 4-fold oxygens. Furthermore, we find excellent agreement between\nthe DFT calculated electronic structure with scanning tunnelling spectroscopy\nand valence XPS measurements."
    },
    {
        "anchor": "Diameter-Dependent Electron Mobility of InAs Nanowires: Temperature-dependent I-V and C-V spectroscopy of single InAs nanowire\nfield-effect transistors were utilized to directly shed light on the intrinsic\nelectron transport properties as a function of nanowire radius. From C-V\ncharacterizations, the densities of thermally-activated fixed charges and trap\nstates on the surface of untreated (i.e., without any surface\nfunctionalization) nanowires are investigated while enabling the accurate\nmeasurement of the gate oxide capacitance; therefore, leading to the direct\nassessment of the field-effect mobility for electrons. The field-effect\nmobility is found to monotonically decrease as the radius is reduced to sub-10\nnm, with the low temperature transport data clearly highlighting the drastic\nimpact of the surface roughness scattering on the mobility degradation for\nminiaturized nanowires. More generally, the approach presented here may serve\nas a versatile and powerful platform for in-depth characterization of\nnanoscale, electronic materials.",
        "positive": "Methylammonium fragmentation in amines as source of localized trap\n  levels and the healing role of Cl in Hybrid Lead-Iodide Perovskites: The resilience to deep traps and localized defect formation is one of the\nimportant aspects that qualify a material as suited photo-absorber in solar\ncell devices. Here we investigate by ab-initio calculations the fundamental\nphysics and chemistry of a number of possible localized defects in hybrid\nmethylammonium lead-iodide perovskites. Our analysis encompasses a number of\npossible molecular fragments deriving from the dissociation of methylammonium.\nIn particular, we found that in stoichiometric conditions both ammonia and\nmethylamine molecules present lone-pair localized levels well within the\nperovskite band gap, while the radical cation CH$_2$NH$_3$$^+$ observed by EPR\nafter irradiation injects partially-occupied levels into the band gap but only\nin $p$-type conditions. These defects are thus potentially capable to\nsignificantly alter absorption and recombination properties. Amazingly, we\nfound that additional interstitial Cl is capable to remove these localized\nstates from the band gap. These results are consistent with the observed\nimprovement of photoabsorption properties due to the Cl inclusion in the\nsolution processing."
    },
    {
        "anchor": "Symmetry preserving lattice collapse in tetragonal SrFe_(2-x)Ru_xAs_2 (x\n  = 0, 0.2) -- a combined experimental and theoretical study: In a joint experimental and theoretical study, we investigate the\nisostructural collapse from the ambient pressure tetragonal phase to a\ncollapsed tetragonal phase for non-superconducting metallic SrFe2As2 and\nSrFe_1.8Ru_0.2As_2. The crystallographic details have been studied using X-ray\npowder diffraction up to 20 GPa pressure in a diamond anvil cell. The\nstructural phase transition occurs at 10 GPa and 9 GPa for SrFe2As2 and\nSrFe_1.8Ru_0.2As_2, respectively. The changes in the unit cell dimensions are\nhighly anisotropic with a continuous decrease of the c lattice parameter with\npressure, while the a-axis length increases until the transition to a collapsed\ntetragonal phase and then continues to decrease. Across the phase transition,\nwe observe a volume reduction of 5% and 4% for SrFe2As2 and SrFe_1.8Ru_0.2As_2,\nrespectively. We are able to discern that Ru substitution on the Fe-site acts\nlike `chemical pressure' to the system. Density-functional theory-based\ncalculations of the electronic structure and electron localizability indicator\nare consistent with the experimental observations. Detailed analysis of the\nelectronic structure in k-space and real space reveals As 4pz interlayer bond\nformation as the driving force of the c/a collapse with a change in the As-As\nbond length of about 0.35ang.",
        "positive": "Large phosphorene in-plane contraction induced by interlayer\n  interactions in graphene-phosphorene heterostructures: Intralayer deformation in van der Waals (vdW) heterostructures is generally\nassumed to be negligible due to the weak nature of the interactions between the\nlayers, especially when the interfaces are found incoherent. In the present\nwork, graphene-phosphorene vdW-heterostructures are investigated with the\nDensity Functional Theory (DFT). The challenge of treating nearly\nincommensurate (very large) supercell in DFT is bypassed by considering\ndifferent energetic quantities in the grand canonical ensemble, alternative to\nthe formation energy, in order to take into account the mismatch elastic\ncontribution of the different layers. In the investigated heterostructures, it\nis found that phosphorene contracts by ~4% in the armchair direction when\ncompared to its free-standing form. This large contraction leads to important\nchanges in term of electronic properties, with the direct electronic optical\ntransition of phosphorene becoming indirect in specific vdW-heterostructures.\nMore generally, such a contraction indicates strong substrate effects in\nsupported or encapsulated phosphorene -neglected hitherto- and paves the way to\nsubstrate-controlled stress- tronic in such 2D crystal. In addition, the\nstability of these vdW-heterostructures are investigated as a function of the\nrotation angle between the layers and as a function of the stacking\ncomposition. The alignment of the specific crystalline directions of graphene\nand phosphorene is found energetically favored. In parallel, several several\nmodels based on DFT-estimated quantities are presented; they allow notably a\nbetter understanding of the global mutual accommodation of 2D materials in\ntheir corresponding interfaces, that is predicted to be non-negligible even in\nthe case of incommensurate interfaces."
    },
    {
        "anchor": "Spin Berry points as crucial for ultrafast demagnetization: Laser-induced ultrafast demagnetization has puzzled researchers around the\nworld for over two decades. Intrinsic complexity in electronic, magnetic, and\nphononic subsystems is difficult to understand microscopically. So far it is\nnot possible to explain demagnetization using a single mechanism, which\nsuggests a crucial piece of information still missing. In this paper, we return\nto a fundamental aspect of physics: spin and its change within each band in the\nentire Brillouin zone. We employ fcc Ni as an example and use an extremely\ndense {\\bf k} mesh to map out spin changes for every band close to the Fermi\nlevel along all the high symmetry lines. To our surprise, spin angular momentum\nat some special {\\bf k} points abruptly changes from $\\pm \\hbar/2$ to $\\mp\n\\hbar/2$ simply by moving from one crystal momentum point to the next. This\nexplains why intraband transitions, which the spin superdiffusion model is\nbased upon, can induce a sharp spin moment reduction, and why electric current\ncan change spin orientation in spintronics. These special {\\bf k} points, which\nare called spin Berry points, are not random and appear when several bands are\nclose to each other, so the Berry potential of spin majority states is\ndifferent from that of spin minority states. Although within a single band,\nspin Berry points jump, when we group several neighboring bands together, they\nform distinctive smooth spin Berry lines. It is the band structure that\ndisrupts those lines. Spin Berry points are crucial to laser-induced ultrafast\ndemagnetization and spintronics.",
        "positive": "Synchrotron Radiation Techniques and their Application to Actinide\n  Materials: Research on actinide materials, both basic and applied, has been greatly\nadvanced by the general techniques available from high-intensity photon beams\nfrom x-ray synchrotron sources. The most important single reason is that such\nx-ray sources can work with minute (e.g., microgram) samples, and at this\nlevel, the radioactive hazards of actinides are much reduced. We start by\ndiscussing the form and encapsulation procedures used for different techniques,\nthen discuss the basic theory for interpreting the results. By reviewing a\nselection of x-ray diffraction (XRD), resonant elastic x-ray scattering (REXS),\nx-ray magnetic circular dichroism (XMCD), resonant and non-resonant inelastic\nscattering (RIXS, NIXS), dispersive inelastic x-ray scattering (IXS), and\nconventional and resonant photoemission experiments, we demonstrate the\npotential of synchrotron radiation techniques in studying lattice and\nelectronic structure, hybridization effects, multipolar order, and lattice\ndynamics in actinide materials."
    },
    {
        "anchor": "Eight-band calculations of strained InAs/GaAs quantum dots compared with\n  one, four, and six-band approximations: The electronic structure of pyramidal shaped InAs/GaAs quantum dots is\ncalculated using an eight-band strain dependent $\\bf k\\cdot p$ Hamiltonian. The\ninfluence of strain on band energies and the conduction-band effective mass are\nexamined. Single particle bound-state energies and exciton binding energies are\ncomputed as functions of island size. The eight-band results are compared with\nthose for one, four and six bands, and with results from a one-band\napproximation in which m(r) is determined by the local value of the strain. The\neight-band model predicts a lower ground state energy and a larger number of\nexcited states than the other approximations.",
        "positive": "Enhanced Thermoelectric Efficiency via Orthogonal Electrical and Thermal\n  Conductances in Phosphorene: Thermoelectric devices that utilize the Seebeck effect convert heat flow into\nelectrical energy and are highly desirable for the development of portable,\nsolid state, passively-powered electronic systems. The conversion efficiencies\nof such devices are quantified by the dimensionless thermoelectric figure of\nmerit (ZT), which is proportional to the ratio of a device's electrical\nconductance to its thermal conductance. High ZT (>2) has been achieved in\nmaterials via all-scale hierarchical architecturing. This efficiency holds at\nhigh temperatures (700K~900K) but quickly diminishes at lower temperatures. In\nthis paper, a recently-fabricated two-dimensional (2D) semiconductor called\nphosphorene (monolayer black phosphorus) is assessed for its thermoelectric\ncapabilities. First-principles and model calculations reveal that phosphorene\npossesses spatially-anisotropic electrical and thermal conductances. The\nprominent electrical and thermal conducting directions are orthogonal to one\nanother, enhancing the ratio of these conductances. As a result, ZT can reach\n2.5 (the criterion for commercial deployment) along the armchair direction of\nphosphorene at T=500K and is greater than 1 even at room temperature given\nmoderate doping (~2 x 10^16 m-2). Ultimately, phosphorene stands out as an\nenvironmentally sound thermoelectric material with unprecedented qualities:\nintrinsically, it is a mechanically flexible material that converts heat energy\nwith high efficiency at low temperatures (~ 300K) - one whose performance does\nnot require any sophisticated engineering techniques."
    },
    {
        "anchor": "Multiscale nature of hysteretic phenomena: Application to CoPt-type\n  magnets: We suggest a workable approach for the description of multiscale\nmagnetization reversal phenomena in nanoscale magnets and apply it to CoPt-type\nalloys. We show that their hysteretic properties are governed by two effects\noriginating at different length scales: a peculiar splitting of domain walls\nand their strong pinning at antiphase boundaries. We emphasize that such\nmultiscale nature of hysteretic phenomena is a generic feature of nanoscale\nmagnetic materials.",
        "positive": "Hot-Carrier Relaxation in Photoinjected ZnSe: A theoretical investigation of the excess energy dissipation of highly\nexcited photoinjected carriers in zinc selenide (ZnSe) is presented. The\ncalculations are performed by solving numerically coupled quantum transport\nequations for the carriers and the optical phonons in order to derive the\nevolution of their nonequilibrium temperatures, dubbed quasitemperatures (or\nnonequilibrium temperatures). It is shown that the carrier energy dissipation\noccurs in a picosecond time scale."
    },
    {
        "anchor": "Thermo - mechanical instabilities in friction contact: The phenomenon of corrugated surfaces is a known technical problem of\ntribological systems; considerable work has been published in the past on the\naspect of rail corrugation of railway systems. Less known is a similar\nphenomenon observed within the cylinder-piston system of advanced automotive\nengines using aluminium cylinders. This paper investigates the condition\nleading to cylinder corrugation in the piston/cylinder system. Material\ninvestigations strongly indicate that heat in the contact is playing a major\nrole. Using basic analytical relationships from contact mechanics, the\ncondition required for the onset of such thermo-mechanical instabilities are\ninvestigated. Using the concept of a critical velocity it is shown that such\ninstabilities can occur for a realistic set of parameters. A significant\ntechnical key factor is the friction coefficient.",
        "positive": "First-Principles Study on Electron-Conduction Properties of Helical Gold\n  Nanowires: Multishell helical gold nanowires (HGNs) suspended between semi-infinite\nelectrodes are found to exhibit peculiar electron-conduction properties by\nfirst-principles calculations based on the density functional theory. Our\nresults that the numbers of conduction channels in the HGNs and their\nconductances are smaller than those expected from a single-atom-row nanowire\nverify the recent experiment. In addition, we obtained a more striking result\nthat in the cases of thin HGNs, distinct magnetic fields are induced by the\nelectron current helically flowing around the shells. This finding indicates\nthat the HGNs can be good candidates for nanometer-scale solenoids."
    },
    {
        "anchor": "Velocity of domain-wall motion induced by electrical current in a\n  ferromagnetic semiconductor (Ga,Mn)As: Current-induced domain-wall motion with velocity spanning over five orders of\nmagnitude up to 22 m/s has been observed by magneto-optical Kerr effect in\n(Ga,Mn)As with perpendicular magnetic anisotropy. The data are employed to\nverify theories of spin-transfer by the Slonczewski-like mechanism as well as\nby the torque resulting from spin-flip transitions in the domain-wall region.\nEvidence for domain-wall creep at low currents is found.",
        "positive": "Tunnel magnetoresistance in alumina, magnesia and composite tunnel\n  barrier magnetic tunnel junctions: Using magnetron sputtering, we have prepared Co-Fe-B/tunnel barrier/Co-Fe-B\nmagnetic tunnel junctions with tunnel barriers consisting of alumina, magnesia,\nand magnesia-alumina bilayer systems. The highest tunnel magnetoresistance\nratios we found were 73% for alumina and 323% for magnesia-based tunnel\njunctions. Additionally, tunnel junctions with a unified layer stack were\nprepared for the three different barriers. In these systems, the tunnel\nmagnetoresistance ratios at optimum annealing temperatures were found to be 65%\nfor alumina, 173% for magnesia, and 78% for the composite tunnel barriers. The\nsimilar tunnel magnetoresistance ratios of the tunnel junctions containing\nalumina provide evidence that coherent tunneling is suppressed by the alumina\nlayer in the composite tunnel barrier."
    },
    {
        "anchor": "Evolution of structural, magnetic and transport properties in\n  MnBi2-xSbxTe4: Here we report the evolution of structural, magnetic and transport properties\nin MnBi$_{2-x}$Sb$_x$Te$_4$ (0$\\leq x \\leq$2) single crystals. MnSb$_2$Te$_4$,\nisostructural to MnBi$_2$Te$_4$, has the lattice parameters of\n\\textit{a}=4.2445(3)$\\AA$ and \\textit{c}=40.869(5)$\\AA$, respectively. With\nincreasing Sb content in MnBi$_{2-x}$Sb$_x$Te$_4$, the \\textit{a}-lattice\ndecreases linearly following the Vegards law while the \\textit{c}-lattice shows\nlittle compositional dependence. The \\textit{a}-lattice contraction occurs by\nreducing Mn-Te-Mn bond angle while Mn-Te bond length remains nearly constant.\nThe anisotropic magnetic properties suggest an antiferromagnetic order below\nT$_N$=19\\,K for MnSb$_2$Te$_4$ with the magnetic moments aligned along the\ncrystallographic \\textit{c}-axis. The antiferromagnetic ordering temperature\nslightly decreases from 24\\,K for MnBi$_2$Te$_4$ to 19\\,K for MnSb$_2$Te$_4$.\nMore dramatic change was observed for the critical magnetic fields required for\nthe spin-flop transition and moment saturation. With increasing Sb content,\nboth critical fields decrease and in MnSb$_2$Te$_4$ a small field of 3\\,kOe is\nenough to saturate the moment. In high magnetic fields, the saturation moment\nshows significant suppression from 3.56$\\mu_B$/Mn for MnBi$_2$Te$_4$ to\n1.57$\\mu_B$/Mn for MnSb$_2$Te$_4$. Data analyses suggest that both the\ninterlayer magnetic interaction and single ion anisotropy decrease with\nincreasing Sb content. The partial substitution of Bi by Sb also dramatically\naffects the transport properties. A crossover from n-type to p-type conducting\nbehavior is observed around x=0.63. Our results show close correlation between\nstructural, magnetic and transport properties in MnBi$_{2-x}$Sb$_x$Te$_4$ and\nthat partial substitution of Bi by Sb is an effective approach to fine tuning\nboth the magnetism and transport properties of MnBi$_{2-x}$Sb$_x$Te$_4$.",
        "positive": "Note: Optical filter method for high-resolution magnetostriction\n  measurement using fiber Bragg grating under millisecond-pulsed high magnetic\n  fields at cryogenic temperatures: High-resolution magnetostriction measurement of $\\Delta L/L\\sim10^{-6}$ at a\nspeed of 5 MHz is performed, using optical filter method as the detection\nscheme for the fiber Bragg grating (FBG) based strain monitor is performed\nunder 35-millisecond pulsed high magnetic fields up to 45 T at 2.2 K. The\nresolution of magnetostriction is about the same order as the conventionally\nreported value from FBG based magnetostriction measurement systems for\nmillisecond pulsed magnetic fields. The measurement speed is $\\sim$100 times\nthe conventional ones. Present system can be a faster alternative for the\nconventional FBG based magnetostriction measurement system for millisecond\npulsed high magnetic fields."
    },
    {
        "anchor": "Correlation of morphology and charge transport in\n  poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT-PSS) films: A wide variation in the charge transport properties of\npoly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) films is\nattributed to the degree of phase-segregation of the excess insulating\npolyanion. The results indicate that the charge transport in PEDOT-PSS can vary\nfrom hopping to critical regime of the metal-insulator transition, depending on\nthe subtle details of morphology. The extent of electrical-connectivity in\nfilms, directly obtained from a temperature dependent high-frequency transport\nstudy, indicates various limiting factors to the transport, which are\ncorrelated with the phase separation process. The low temperature\nmagnetotransport further supports this morphology-dependent transport scenario.",
        "positive": "Deformation potential extraction and computationally efficient mobility\n  calculations in silicon from first principles: We present a first-principles framework to extract deformation potentials in\nSilicon based on density-functional theory (DFT) and density-functional\nperturbation theory (DFPT). We compute the electronic band structures, phonon\ndispersion relations, and electron-phonon matrix elements to extract\ndeformation potentials for acoustic and optical phonons for all possible\nprocesses. The matrix elements clearly show the separation between intra- and\ninter-valley scattering in the conduction band, and quantify the strength of\nthe scattering events in the degenerate bands of the valence band. We then use\nan advanced numerical Boltzmann transport equation (BTE) simulator that couples\nDFT electronic structures and energy/momentum-dependent scattering rates to\ncompute the transport properties for electrons and holes. By incorporating\nionized impurity scattering as well, we calculate the n-type and p-type\nmobility versus carrier density and make comparisons to experiments, indicating\nexcellent agreement. The fact that the method we present uses well-established\ntheoretical tools and requires the extraction of only a limited number of\nmatrix elements, makes it generally computationally very attractive, especially\nfor semiconductors with a large unit cell and lower symmetry."
    },
    {
        "anchor": "Spin-Phonon Coupling and High Pressure Phase Transitions of RMnO3 (R= Ca\n  and Pr): An Inelastic Neutron Scattering and First Principle Studies: We report inelastic neutron scattering measurements over 7-1251 K in CaMnO3\ncovering various phase transitions, and over 6-150 K in PrMnO3 covering the\nmagnetic transition. The excitations around 20 meV in CaMnO3 and at 17 meV in\nPrMnO3 are found to be associated with magnetic origin. In spite of similarity\nof the structure of the two compounds, the neutron inelastic spectrum of PrMnO3\nexhibits broad features at 150 K unlike well-defined peaks in the spectrum of\nCaMnO3. This might result from the difference in nature of interactions in the\ntwo compounds (magnetic and Jahn-Teller distortion). The interpretation and\nanalysis of the observed phonon spectra have been performed using ab-initio\nphonon calculations. We also discuss the effect of pressure on the structural\ndistortions in the orthorhombic phase of CaMnO3 and PrMnO3. On application of\npressure, we found that the variations of Mn-O distances are isotropic for\nCaMnO3 and highly anisotropic for PrMnO3. The calculated structure as a\nfunction of pressure in PrMnO3 shows that suppression of Jahn-Teller distortion\nand insulator to metal transition occurs simultaneously. Our calculations show\nthat this transition may not be associated with the occurrence of the\ntetragonal phase above 20 GPa as reported in the literature, since the\ntetragonal phase is found to be dynamically unstable although it is found to be\nenergetically favored over the orthorhombic phase above 20 GPa. CaMnO3 does not\nshow any phase transition up to 60 GPa.",
        "positive": "When atomic-scale resolution is not enough: Spatial effects in in situ\n  model catalyst studies: We investigate transport effects in in situ studies of defined model\ncatalysts using a multi-scale modeling approach integrating first-principles\nkinetic Monte Carlo simulations into a fluid dynamical treatment. We\nspecifically address two isothermal flow setups: i) a channel flow with the\ngas-stream approaching the single crystal from the side, as is representative\nfor reactor scanning tunneling microscopy experiments; and ii) a stagnation\nflow with perpendicular impingement. Using the CO oxidation at RuO2 (110) as\nshowcase we obtain substantial variations in the gas-phase pressures between\nthe inlet and the catalyst surface. In the channel geometry the mass transfer\nlimitations lead furthermore to pronounced lateral changes in surface\ncomposition across the catalyst surface. This prevents the aspired direct\nrelation between activity and catalyst structure. For the stagnation flow the\nlateral variations are restricted to the edges of the catalyst. This allows to\naccess the desired structure-activity relation using a simple model."
    },
    {
        "anchor": "Berry Curvature Enhanced Nonlinear Photogalvanic Response of Type-II\n  Weyl Cone: The experimental manifestation of topological effects in bulk materials under\nambient conditions, especially those with practical applications, has attracted\nenormous research interest. Recent discovery of Weyl semimetal provides an\nideal material platform for such endeavors. The Berry curvature in a Weyl\nsemimetal becomes singular at the Weyl node, creating an effective magnetic\nmonopole in the k-space. A pair of Weyl nodes carry quantized effective\nmagnetic charges with opposite signs, and therefore, opposite chirality.\nAlthough Weyl-point-related signatures such as chiral anomaly and non-closing\nsurface Fermi arcs have been detected through transport and ARPES measurements,\ndirect experimental evidence of the effective k-space monopole of the Weyl\nnodes has so far been lacking. In this work, signatures of the singular\ntopology in a type-II Weyl semimetal TaIrTe4 is revealed in the photo\nresponses, which are shown to be directly related to the divergence of Berry\ncurvature. As a result of the divergence of Berry curvature at the Weyl nodes,\nTaIrTe4 exhibits unusually large photo responsivity of 130.2 mA/W with 4-{\\mu}m\nexcitation in an unbiased field effect transistor at room temperature arising\nfrom the third-order nonlinear optical response. The room temperature mid-IR\nresponsivity is approaching the performance of commercial HgCdTe detector\noperating at low temperature, making Type-II Weyl semimetal TaIrTe4 of\npractical importance in terms of photo sensing and solar energy harvesting.\nFurthermore, the high shift photocurrent response at the Weyl cones is found to\nenhance the circularly polarized galvanic response from Weyl cones with\nopposite chirality, which opens new experimental possibilities for studying and\ncontrolling the chiral polarization of Weyl Fermions through an in-plane DC\nelectric field in addition to the optical helicities.",
        "positive": "Carbon chains grown perpendicularly on graphene: Based on first-principles calculations we predict a peculiar growth process,\nwhere carbon adatoms adsorbed to graphene readily diffuse above room\ntemperature and nucleate segments of linear carbon chains attached to graphene.\nThese chains grow longer on graphene through insertion of carbon atoms one at a\ntime from the bottom end and display a self-assembling behavior. Eventually,\ntwo allotropes of carbon, namely graphene and cumulene are combined to exhibit\nimportant functionalities. The segments of carbon chains on graphene become\nchemically active sites to bind foreign atoms or large molecules. When bound to\nthe ends of carbon chains, transition metal atoms, Ti, Co and Au, attribute a\nmagnetic ground state to graphene sheets and mediate stable contacts with\ninterconnects. We showed that carbon chains can grow also on single wall carbon\nnanotubes."
    },
    {
        "anchor": "Fragility of Fermi arcs in Dirac semimetals: We use tunable, vacuum ultraviolet laser-based angle-resolved photoemission\nspectroscopy and density functional theory calculations to study the electronic\nproperties of Dirac semimetal candidate cubic PtBi${}_{2}$. In addition to bulk\nelectronic states we also find surface states in PtBi${}_{2}$ which is expected\nas PtBi${}_{2}$ was theoretical predicated to be a candidate Dirac semimetal.\nThe surface states are also well reproduced from DFT band calculations.\nInterestingly, the topological surface states form Fermi contours rather than\ndouble Fermi arcs that were observed in Na$_3$Bi. The surface bands forming the\nFermi contours merge with bulk bands in proximity of the Dirac points\nprojections, as expected. Our data confirms existence of Dirac states in\nPtBi${}_{2}$ and reveals the fragility of the Fermi arcs in Dirac semimetals.\nBecause the Fermi arcs are not topologically protected in general, they can be\ndeformed into Fermi contours, as proposed by [Kargarian {\\it et al.}, PNAS\n\\textbf{113}, 8648 (2016)]. Our results demonstrate validity of this theory in\nPtBi${}_{2}$.",
        "positive": "Ferromagnetism as a universal feature of nanoparticles of the otherwise\n  nonmagnetic oxides: Room-temperature ferromagnetism has been observed in the nanoparticles (7 -\n30 nm dia) of nonmagnetic oxides such as CeO2, Al2O3, ZnO, In2O3 and SnO2. The\nsaturated magnetic moments in CeO_2 and Al_2O_3 nanoparticles are comparable to\nthose observed in transition metal doped wide band semiconducting oxides. The\nother oxide nanoparticles show somewhat lower values of magnetization but with\na clear hysteretic behavior. Conversely, the bulk samples obtained by sintering\nthe nanoparticles at high temperatures in air or oxygen became diamagnetic. As\nthere were no magnetic impurities present, we assume that the origin of\nferromagnetism may be due to the exchange interactions between localized\nelectron spin moments resulting from oxygen vacancies at the surfaces of\nnanoparticles. We suggest that ferromagnetism may be a universal characteristic\nof nanopartilces of metal oxides"
    },
    {
        "anchor": "PFO-BPy Solubilizers for SWNTs: Modelling of Polymers from Oligomers: Due to their exeptional physical properties, single walled carbon nanotubes\n(SWNTs) embedded in organic polymers (polymer-SWNT hybrid systems) are\npromising materials for organic photovoltaic (OPV) devices. Already at the SWNT\nsorting and debundling step, polymers such as the copolymer of\n9,9-dioctylfluorenyl-2,7-diyl and bipyridine (PFO-BPy) are used as\nsolubilizers. However, to model polymer-SWNT hybrid systems, we must first\ndetermine the smallest oligomer needed to sufficiently describe the electronic\nand optical absorption properties of the polymer. To do so, we use time\ndependent density functional theory (TDDFT) to model the PFO-BPy polymer using\nthe monomers, dimers and trimers of the PFO-BPy and Py-PFO-Py building blocks,\nwhich are also compared to the infinitely long polymer. We find the Py-PFO-Py\nmonomer, with shortened side chains, already describes the PFO-BPy polymer\nwithin the expected accuracies of TDDFT.",
        "positive": "A new methodology for the extraction of anharmonic force constants from\n  first principles density functional calculations: A new method for extracting force constants (FC) from first principles is\nintroduced. It requires small supercells but very accurate forces. In\nprinciple, provided that forces are accurate enough, it can extract harmonic as\nwell as anharmonic FCs up to any neighbor shell. Symmetries of the FCs as well\nas those of the lattice are used to reduce the number of parameters to be\ncalculated. Results are illustrated for the case of Lennard-Jones potential\nwhere forces are exact and FCs can be calculated analytically, and Si in the\ndiamond structure. The latter are compared to previously calculated harmonic\nFCs."
    },
    {
        "anchor": "Shear Induced Structural Ordering of a Model Metallic Glass: We report results of non-equilibrium molecular dynamics simulations of a\none-component glassy system under the influence of a shear flow, with the aim\nof investigating shear induced ordering of this system. In spite of the very\nlow temperature, the system transforms into a strained crystalline state\nthrough well defined nucleation events. Various characteristics of the observed\nordering at different strain rates and temperatures are discussed. We also\ndefine and discuss the transition rates.",
        "positive": "Exploring $\\rm Mg^{2+}$ and $\\rm Ca^{2+}$ Conductors Via Solid-State\n  Metathesis Reactions: Magnesium and calcium batteries offer promising energy storage solutions\ncharacterised by cost-effectiveness, safety, and high energy density. However,\nthe scarcity of viable electrode and electrolyte materials vastly hinders their\nadvancement. This study utilises solid-state metathetical reactions involving\npredominantly chalcogen- and pnictogen-based honeycomb layered oxides with\nalkaline-earth halides/nitrates to synthesise $\\rm Mg^{2+}$- and $\\rm\nCa^{2+}$-based materials previously achievable only under\nhigh-temperature/high-pressure conditions, as well as new metastable materials\nwith unique crystal versatility. Particularly, we employ metathetical reactions\ninvolving $\\rm Li_4MgTeO_6$, $\\rm Na_2Mg_2TeO_6$, and $\\rm Na_4MgTeO_6$ with\n$\\rm MgCl_2$\\,/\\,$\\rm Mg(NO_3)_2$ or $\\rm Ca(NO_3)_2$ at temperatures not\nexceeding 500 $^\\circ$C to produce $\\rm Mg_3TeO_6$ polymorphs, ilmenite-type\n$\\rm CaMg_2TeO_6$\\,/\\,$\\rm Mg_2CaTeO_6$, and double perovskite $\\rm\nCa_2MgTeO_6$. Thus, we demonstrate that these materials, conventionally\nrequiring gigascale pressures and high temperatures (>1000$^\\circ$C) for their\nproper synthesis, are now readily accessible at ambient pressure and\nconsiderably lower temperatures. Meanwhile, despite sub-optimal pellet\ndensities, the synthesised ilmenite-type $\\rm Mg_3TeO_6$ and double perovskite\n${\\rm Ca}_2M{\\rm TeO_6}$ ($M = \\rm Mg, Ca, Zn$)} materials exhibit remarkable\nbulk ionic conductivity at room temperature, marking them as promising\ncompositional spaces for exploring novel $\\rm Mg^{2+}$ and $\\rm Ca^{2+}$\nconductors. Furthermore, this study extends the applicability of metathetical\nreactions to attain Mg- or Ca-based bismuthates, antimonates, ruthenates,\ntungstates, titanates, phosphates, and silicates, thus opening avenues to novel\nhigh-entropy multifunctional nanomaterial platforms with utility in energy\nstorage and beyond."
    },
    {
        "anchor": "Spin-induced symmetry breaking in orbitally ordered NiCr_2O_4 and\n  CuCr_2O_4: At room temperature, the normal oxide spinels NiCr_2O_4 and CuCr_2O_4 are\ntetragonally distorted and crystallize in the I4_1/amd space group due to\ncooperative Jahn-Teller ordering driven by the orbital degeneracy of\ntetrahedral Ni$^{2+}$ ($t_2^4$) and Cu$^{2+}$ ($t_2^5$). Upon cooling, these\ncompounds undergo magnetic ordering transitions; interactions being somewhat\nfrustrated for NiCr_2O_4 but not for CuCr_2O_4. We employ variable-temperature\nhigh-resolution synchrotron X-ray powder diffraction to establish that at the\nmagnetic ordering temperatures there are further structural changes, which\nresult in both compounds distorting to an orthorhombic structure consistent\nwith the Fddd space group. NiCr_2O_4 exhibits additional distortion, likely\nwithin the same space group, at a yet-lower transition temperature of $T$ = 30\nK. The tetragonal to orthorhombic structural transition in these compounds\nappears to primarily involve changes in NiO_4 and CuO_4 tetrahedra.",
        "positive": "Material design of indium based compounds: possible candidates for\n  charge, valence, and bond disproportionation and superconductivity: We design and investigate the physical properties of new indium compounds\nAInX$_{3}$ (A = alkali metals, X = F or Cl). We find nine new In based\nmaterials in their ground state and are thermodynamically stable but are not\nreported in ICSD (Inorganic Crystal Structure Database). We also discuss\nseveral metastable structures. This new series of materials display multiple\nvalences, charge and bond disproportionation, and dimerization. The most common\nvalence of In is 3+. We also find two rare alternatives, one has In$^{2+}$ with\nIn-In dimerization and the other shows valence disproportionation to In$^{1+}$\nand In$^{3+}$ with bond disproportionation. We study the possibility of\nsuperconductivity in these new In compounds and find that CsInF$_{3}$ has a\ntransition temperature about 24 K with sufficient hole doping and pressure."
    },
    {
        "anchor": "Persistent spin textures in halide perovskites induced by uniaxial\n  stress: Persistent spin textures are highly desirable for applications in spintronics\nas they may allow for long carrier spin lifetimes. However, they are also rare\nas only four point groups can host such textures, and even for these four\ngroups, the emergence of persistent spin textures requires a delicate balance\nbetween coupling parameters, which control the strength of spin-momentum\ninteractions. We use first-principles density functional simulations to predict\nthe possibility of achieving these desirable spin textures through the\napplication of uniaxial stress. Hybrid organic-inorganic perovskite MPSnBr$_3$\n(MP = CH$_3$PH$_3$) is a ferroelectric semiconductor which exhibits persistent\nspin textures in the near to its conduction band minimum and mostly Rashba type\nin the vicinity of its valence band maximum. Application of uniaxial stress\nleads to the gradual evolution of the valence bands spin textures from mostly\nRashba type to persistent ones under tensile load and to pure Rashba or\npersistent ones under compressive load. We also report that the material\nexhibits flexibility, rubber-like response, and both positive and negative\npiezoelectric constants. Combination of such properties may create\nopportunities for a flexible/rubbery spintronic devices.",
        "positive": "Adiabatic-Connection-Fluctuation-Dissipation approach to the long-range\n  behavior of the exchange-correlation energy at metal surfaces: A numerical\n  study for jellium slabs: A still open issue in many-body theory is the asymptotic behavior of the\nexchange-correlation energy and potential in the vacuum region of a metal\nsurface. Here we report a numerical study of the position-dependent\nexchange-correlation energy for jellium slabs, as obtained by combining the\nformally exact adiabatic-connection-fluctuation-dissipation theorem with either\ntime-dependent density-functional theory or an inhomogeneous\nSingwi-Tosi-Land-Sj\\\"olander approach. We find that the inclusion of\ncorrelation allows to obtain well-converged semi-infinite-jellium results\n(independent of the slab thickness) that exhibit an image-like asymptotic\nbehavior close to the classical image potential $V_{im}(z)=-e^2/4z$."
    },
    {
        "anchor": "Driving forces for Ag-induced periodic faceting of vicinal Cu(111): Adsorption of submonolayer amounts of Ag on vicinal Cu(111) induces periodic\nfaceting. The equilibrium structure is characterized by Ag-covered facets that\nalternate with clean Cu stripes. In the atomic scale, the driving force is the\nmatching of Ag(111)-like packed rows with Cu(111) terraces underneath. This\ndetermines the preference for the facet orientation and the evolution of\ndifferent phases as a function of coverage. Both Cu and Ag stripe widths can be\nvaried smoothly in the 3-30 nm range by tuning Ag coverage, allowing to test\ntheoretical predictions of elastic theories.",
        "positive": "Evolutionary computing and machine learning for the discovering of\n  low-energy defect configurations: Density functional theory (DFT) has become a standard tool for the study of\npoint defects in materials. However, finding the most stable defective\nstructures remains a very challenging task as it involves the solution of a\nmultimodal optimization problem with a high-dimensional objective function.\nHitherto, the approaches most commonly used to tackle this problem have been\nmostly empirical, heuristic and/or based on domain knowledge. In this\ncontribution, we describe an approach for exploring the potential energy\nsurface based on the covariance matrix adaption evolution strategy (CMA-ES) and\nsupervised and unsupervised machine learning models. We show how the original\nCMA-ES can be modified to suit the specific problem of DFT studies of point\ndefects in the dilute limit. The resulting algorithm depends only on a limited\nset of physically interpretable hyperparameters. The approach offers a robust\nand systematic way for finding low-energy configurations of point defects in\nsolids. We demonstrate the applicability and moderate computational cost on the\nintrinsic defects in silicon. We also apply the methodology to the neutral\noxygen vacancy oxygen vacancy in TiO$_2$ anatase and reproduce the known defect\nstructures. Furthermore, a new defect structure, stable at the level of hybrid\ndensity functional theory and characterized by a delocalized electronic\nstructure, is found for this system."
    },
    {
        "anchor": "Concurrent growth and formation of electrically contacted monolayer\n  transition metal dichalcogenides on bulk metallic patterns: While new species and properties of two-dimensional (2D) materials are being\nreported with extraordinary regularity, a significant bottleneck in the field\nis the ability to controllably process material into working devices. We report\na chemical vapor deposition process to selectively grow 2D material in a\ndeterministic manner around lithographically defined bulk metallic patterns\nwhich concurrently provide as-grown contacts to the material. Monolayer films,\nwith lateral extent of up to hundreds of microns are controllably grown on and\naround patterned regions of transition metals. By using different combinations\nof metallic pattern and oxide based precursor, heterostructured MoS2/WS2 growth\nhas been observed as well. The materials display strong luminescence, monolayer\nRaman signatures, and relatively large crystal domains. In addition to\nproducing high optical quality monolayer material deterministically and\nselectively over large regions, the metallic patterns remain conductive and\ntherefore have the advantage of providing as-grown metallic contacts to the\nmaterial, offering a path for simple device fabrication and large scale\nproduction",
        "positive": "Orientational Ordering and Binding in Alkali doped C60 solids: The binding energy of A3C60, a conductor, is described well by an ionic solid\ntype calculation. This succeeds because there is little overlap between\nmolecular wave functions on neighbouring sites, so that electrons are\npractically localized on-shell. This leads one to believe that even in A4C60\nand A6C60 systems such calculation may suffice. However, for large charge on\nthe anion, there is a possibility for some electrons to delocalize and go into\nthe s-band. We calculate binding energy, keeping these delocalised electrons x,\nas a parameter and minimize the energy w.r.t. it. We take the intermolecular\ninteraction to be arising out of a C-C potential of 6-exp form and a screened\nCoulomb interaction between the anions and cations and among themselves. Model\ncalculations are presented for K1C60, K3C60, K4C60 and K6C60 for which the\nminimum energy state shows no delocalisation. Cohesive Energy dependence on\nLattice constant is used to calculate Bulk Modulus for all systems. We have got\na reasonably good resemblance with experimental values. Further, we observe\nthat the cohesive energy shows poor resemblance with experimental values.\nFurther, delocalisation of a fraction of electron at the centre of double bond\nshow considerable increase in cohesive energy."
    },
    {
        "anchor": "Charge fluctuations and the tunneling spectra of non-magnetic metallic\n  nanoparticles: We present microscopic transport calculations of the tunneling spectra of\nnon-magnetic metal nanoparticles. We show that charge fluctuations give rise to\ntunneling resonances of a new type. Positive and negative fluctuations have\ndiffering kinetics and thus account for previously unexplained spectral\nfeatures that are found experimentally under only forward or only reverse\napplied bias. The observed clustering of tunneling resonances of Al\nnanoparticles arises naturally from our theory.",
        "positive": "Momentum-dependent resonant inelastic X-ray scattering at the Si K edge\n  of 3C-SiC: A theoretical study on a relation between spectra and valence band\n  dispersion: We theoretically demonstrate that a resonant inelastic x-ray scattering\n  (RIXS) with a sizable momentum transfer can be utilized to study valence band\ndispersion for broad band materials. We take RIXS at the Si K edge of 3C-SiC as\na typical example. The RIXS spectra are calculated by systematically changing\nthe transferred momentum, an incident photon polarization and an incident\nphoton energy, on the basis of an ab initio calculation. We find that the\nspectra depend heavily on both the transferred momentum and the incident photon\npolarization, and the peaks in the spectra correspond to the energies of the\nvalence bands. We conclude that the information on the energy dispersion of\nvalence bands can be extracted from the transferred momentum dependence of the\nRIXS spectra. These findings lead to further application for RIXS when\ninvestigating the band structure of broad band materials."
    },
    {
        "anchor": "Modeling of micro- and nano-scale domain recording by high-voltage\n  atomic force microscopy in ferroelectrics-semiconductors: The equilibrium sizes of micro- and nano-domains caused by electric field of\natomic force microscope tip in ferroelectric semiconductor crystals have been\ncalculated. The domain was considered as a prolate semi-ellipsoid with rather\nthin domain walls. For the first time we modified the Landauer model allowing\nfor semiconductor properties of the sample and the surface energy of the domain\nbutt. The free carriers inside the crystal lead to the formation of the\nscreening layer around the domain, which partially shields its interior from\nthe depolarization field. We expressed the radius and length of the domain\nthough the crystal material parameters (screening radius, spontaneous\npolarization value, dielectric permittivity tensor) and atomic force microscope\ntip characteristics (charge, radius of curvature). The obtained dependence of\ndomain radius via applied voltage is in a good quantitative agreement with the\nones of submicron ferroelectric domains recorded by high-voltage atomic force\nand scanning probe microscopy in LiNbO3 and LiTaO3 crystals.",
        "positive": "Homogenization of membrane and pillar photonic crystals: We study wave propagation and diffraction in a bidimensional photonic crystal\nwith finite height, in case where the wavelength is large with respect to the\nperiod of the structure. The device is made of materials with anisotropic\npermittivity and permeability tensors. We derive rigorously the homogenized\nsystem, using the concept of two-scale convergence. The effective permittivity\nand permeability tensors turn out to be that of a two-dimensional photonic\ncrystal with infinite height."
    },
    {
        "anchor": "Atomic-scale visualization of initial growth of homoepitaxial SrTiO3\n  thin film on an atomically ordered substrate: The initial homoepitaxial growth of SrTiO3 on a (\\surd13\\times\\surd13) -\nR33.7{\\deg}SrTiO3(001) substrate surface, which can be prepared under oxide\ngrowth conditions, is atomically resolved by scanning tunneling microscopy. The\nidentical (\\surd13\\times\\surd13) atomic structure is clearly visualized on the\ndeposited SrTiO3 film surface as well as on the substrate. This result\nindicates the transfer of the topmost Ti-rich (\\surd13\\times\\surd13) structure\nto the film surface and atomic-scale coherent epitaxy at the film/substrate\ninterface. Such atomically ordered SrTiO3 substrates can be applied to the\nfabrication of atom-by-atom controlled oxide epitaxial films and\nheterostructures.",
        "positive": "Theoretical and Experimental Investigation on Structural, Electronic and\n  Magnetic Properties of layered Mn5O8: We have investigated the crystal, electronic, and magnetic structure of Mn5O8\nby means of state of-the-art density functional theory calculations and neutron\npowder diffraction (NPD) measurements. This compound stabilizes in the\nmonoclinic structure with space group C2/m where the Mn ions are in the\ndistorted octahedral and trigonal prismatic coordination with oxygen atoms. The\ncalculated structural parameters based on total energy calculations are found\nto be in excellent agreement with low temperature NPD measurements when we\naccounted correct magnetic structure and Coulomb correlation effect into the\ncomputation. Bond strength analysis based on crystal orbital Hamiltonian\npopulation between constituents indicating strong anisotropy in the bonding\nbehavior which results in layered nature of its crystal structure. Using fully\nrelativistic generalized-gradient approximation with Hubbard U (GGA+U) we found\nthat the magnetic ordering in Mn5O8 is A-type antiferromagnetic and the\ndirection of easy axis is [1 0 0] in agreement with susceptibility and NPD\nmeasurements. However, the calculation without the inclusion of HubbardU leads\nto ferrimagnetic half metal as ground state contradictory to experimental\nfindings, indicating the presence of strong Coulomb correlation effect in this\nmaterial. The GGA calculations without Coulomb correction effect itself is\nsufficient to reproduce our experimentally observed magnetic moments in various\nMn sites."
    },
    {
        "anchor": "Adsorbate aggregation and relaxation of low-frequency vibrations: We present a study of resonant vibrational coupling between adsorbates and an\nelastic substrate at low macroscopic coverages. In the first part of the paper\nwe consider the situation when adsorbates form aggregates with high local\ncoverage. Based upon our previously published theory, we derive formulas\ndescribing the damping rate of adsorbate vibrations for two cases of such\naggregation: (i) adsorbates attached to step edges and (ii) adsorbates forming\ntwo-dimensional islands. We have shown that damping is governed by local\ncoverage. Particularly, for a wide range of resonant frequencies, the damping\nrate of adsorbates forming well separated islands is described by the damping\nrate formula for a periodic overlayer with the coverage equal to the local\ncoverage in the island. The second part of the paper is devoted to facilitating\nthe evaluation of damping rates for a disordered overlayer. The formula\ndescribing the damping rate involves the parameter $\\beta$ which is related to\nthe local density of phonon states at the substrate surface and does not allow\na closed-form representation. For substrates of isotropic and cubic symmetries,\nwe have developed a good analytical approximation to this parameter. For a vast\nmajority of cubic substrates the difference between the analytical\napproximation and numerical calculation does not exceed 4%.",
        "positive": "Nanofaceting as a stamp for periodic graphene charge carrier modulations: The exceptional electronic properties of monoatomic thin graphene sheets\ntriggered numerous original transport concepts, pushing quantum physics into\nthe realm of device technology for electronics, optoelectronics and\nthermoelectrics. At the conceptual pivot point is the particular twodimensional\nmassless Dirac fermion character of graphene charge carriers and its volitional\nmodification by intrinsic or extrinsic means. Here, interfaces between\ndifferent electronic and structural graphene modifications promise exciting\nphysics and functionality, in particular when fabricated with atomic precision.\nIn this study we show that quasiperiodic modulations of doping levels can be\nimprinted down to the nanoscale in monolayer graphene sheets. Vicinal copper\nsurfaces allow to alternate graphene carrier densities by several 10^13\ncarriers per cm^2 along a specific copper high-symmetry direction. The process\nis triggered by a self-assembled copper faceting process during\nhigh-temperature graphene chemical vapor deposition, which defines interfaces\nbetween different graphene doping levels at the atomic level."
    },
    {
        "anchor": "Crystal Structures and Phase Stability of the Li$_2$S-P$_2$S$_5$ System\n  from First Principles: The Li$_2$S-P$_2$S$_5$ pseudo-binary system has been a valuable source of\npromising superionic conductors, with $\\alpha$-Li$_3$PS$_4$,\n$\\beta$-Li$_3$PS$_4$, HT-Li$_7$PS$_6$, and Li$_7$P$_3$S$_{11}$ having excellent\nroom temperature Li-ion conductivity > 0.1 mS/cm. The metastability of these\nphases at ambient temperature motivates a study to quantify thermodynamic\naccessibility. Through calculating the electronic, configurational, and\nvibrational sources of free energy from first principles, a phase diagram of\nthe crystalline Li$_2$S-P$_2$S$_5$ space is constructed. Well-established phase\nstability trends from experiments are recovered, such as polymorphic phase\ntransitions in Li$_7$PS$_6$ and Li$_3$PS$_4$, and the metastability of\nLi$_7$P$_3$S$_{11}$ at high temperature. At ambient temperature, it is\npredicted that all superionic conductors in this space are indeed metastable,\nbut thermodynamically accessible. Vibrational and configurational sources of\nentropy are shown to be essential towards describing the stability of\nsuperionic conductors. New details of the Li sublattices are revealed, and are\nfound to be crucial towards accurately predicting configurational entropy. All\nsuperionic conductors contain significant configurational entropy, which\nsuggests an inherent correlation between superionic conductivity and high\nconfigurational entropy.",
        "positive": "Open top anodic Ta3N5 nanotubes for higher solar water splitting\n  efficiency: In the present work we grow self-organized Ta2O5 nanotube layers in a\nH2SO4/NH4F electrolyte at various elevated temperatures. Under optimized\nconditions we obtain 4 {\\mu}m long nanotubes that are well adherent to the\nsubstrate and can be grown very homogenous over large surface areas. Moreover,\nthe key advantage of this approach is that an open top morphology (initiation\nlayer free) is obtained. After a suitable conversion treatment in NH3\natmosphere Ta3N5 nanotubes are obtained, that after (Co-Pi+Co(OH)x)\nmodification provide, under AM 1.5G illumination conditions, a\nphotoelectrochemical current response of 4.7 mA cm-2 at 1.23 V vs RHE."
    },
    {
        "anchor": "Line defects in Graphene: How doping affects the electronic and\n  mechanical properties: Graphene and carbon nanotubes have extraordinary mechanical and electronic\nproperties. Intrinsic line defects such as local non-hexagonal reconstructions\nor grain boundaries, however, significantly reduce the tensile strength, but\nfeature exciting electronic properties. Here, we address the properties of line\ndefects in graphene from first-principles on the level of full-potential\ndensity-functional theory, and assess doping as one strategy to strengthen such\nmaterials. We carefully disentangle the global and local effect of doping by\ncomparing results from the virtual crystal approximation with those from local\nsubstitution of chemical species, in order to gain a detailed understanding of\nthe breaking and stabilization mechanisms. We find that n-type doping or local\nsubstitution with nitrogen increases the ultimate tensile strength\nsignificantly. In particular, it can stabilize the defects beyond the ultimate\ntensile strength of the pristine material. We therefore propose this as a key\nstrategy to strengthen graphenic materials. Furthermore, we find that doping\nand/or applying external stress lead to tunable and technologically interesting\nmetal/semi-conductor transitions.",
        "positive": "The quantum-mechanical position operator and the polarization problem: The position operator (defined within Schroedinger representation as usual)\nbecomes meaningless when the usual Born-von Karman periodic boundary conditions\nare adopted: this fact is at the root of the polarization problem. I show how\nto define the position expectation value by means of rather peculiar many-body\n(multiplicative) operator acting on the wavefunction of the extended system.\nThis definition can be regarded as the generalization of a precursor work,\napparently unrelated to the polarization problem. For uncorrelated electrons,\nthe present finding coincides with the so-called \"single-point Berry phase\"\nformula, which can hardly be regarded as the approximation of a continuum\nintegral, and is computationally very useful for disordered systems.\nSimulations which are based on this concept are being performed by several\ngroups."
    },
    {
        "anchor": "Tuning band alignment at a semiconductor-crystalline oxide\n  heterojunction via electrostatic modulation of the interfacial dipole: We demonstrate that the interfacial dipole associated with bonding across the\nSrTiO3/Si heterojunction can be tuned through space charge, thereby enabling\nthe band alignment to be altered via doping. Oxygen impurities in Si act as\ndonors that create space charge by transferring electrons across the interface\ninto SrTiO3. The space charge induces an electric field that modifies the\ninterfacial dipole, thereby tuning the band alignment from type-II to type-III.\nThe transferred charge, resulting in built-in electric fields, and change in\nband alignment are manifested in electrical transport and hard x-ray\nphotoelectron spectroscopy measurements. Ab initio models reveal the interplay\nbetween polarization and band offsets. We find that band offsets can be tuned\nby modulating the density of space charge across the interface. Functionalizing\nthe interface dipole to enable electrostatic altering of band alignment opens\nnew pathways to realize novel behavior in semiconducting heterojunctions.",
        "positive": "Theory of large-scale matrix computation and applications to electronic\n  structure calculation: We review our recently developed methods for large-scale electronic structure\ncalculations, both in one-electron theory and many-electron theory. The method\nare based on the density matrix representation, together with the Wannier state\nrepresentation and the Krylov subspace method, in one-electron theory of\na-few-tens nm scale systems. The hybrid method of quantum mechanical molecular\ndynamical simulation is explained.The Krylov subspace method, the CG (conjugate\ngradient) method and the shifted-COCG (conjugate orthogonal conjugate gradient)\nmethod, can be applied to the investigation of the ground state and the\nexcitation spectra in many-electron theory. The mathematical foundation of the\nKrylov subspace method for large-scale matrix computation is focused and the\nkey technique of the shifted-COCG method, e.g. the collinear residual and seed\nswitching, is explained. A wide variety of applications of these extended novel\nalgorithm is also explained. These are the fracture formation and propagation,\nliquid carbon and formation process of gold nanowires, together with the\napplication to the extend Hubbard model."
    },
    {
        "anchor": "Hydrogen abstraction from metal surfaces: When electron-hole pair\n  excitations strongly affect hot-atom recombination: Using molecular dynamics simulations, we predict that the inclusion of\nnonadiabatic electronic excitations influences the dynamics of preadsorbed\nhydrogen abstraction from the W(110) surface by hydrogen scattering. The\nhot-atom recombination, which involves hyperthermal diffusion of the impinging\natom on the surface, is significantly affected by the dissipation of energy\nmediated by electron-hole pair excitations at low coverage and low incidence\nenergy. This issue is of importance as this abstraction mechanism is thought to\nlargely contribute to molecular hydrogen formation from metal surfaces.",
        "positive": "First-principles calculation on the electronic structures, phonon\n  dynamics, and electrical conductivities of Pb$_{10}$(PO$_4$)$_6$O and\n  Pb$_9$Cu(PO$_4$)$_6$O compounds: Superconducting materials with high critical temperature have the potential\nto revolutionize many fields, including military, electronic communications,\nand power energy. Therefore, Scientists around the world have been tirelessly\nworking with the ultimate goal of achieving high temperature superconductivity.\nIn 2023, a preprint by S. Lee et al in South Korea claimed the discovery of\nultra-high-temperature superconductivity with a critical temperature of up to\n423 K in Cu-doped lead-apatite (LK-99) (arXiv:2307.12008, arXiv:2307.12037),\nwhich caused a worldwide sensation and attention. Herein, the electronic\nstructures, phonon dynamics, and electrical conductivities of LK-99 and its\nparent compound lead-apatite have been calculated using first-principles\nmethods. The results show that the lead-apatite compound and the LK-99 compound\nare insulator and half-metal respectively. The flat band characteristic is\nconsistent with previous calculations. The electrical conductivity of LK-99\ncompound shows two extreme point, and the electrical conductivity along the\nC-axis increases significantly after 400 K. The phonon dispersion spectra of\nthe compounds were investigated, demonstrating their dynamic instability."
    },
    {
        "anchor": "Structural transitions in dense disordered silicon from quantum-accurate\n  ultra-large-scale simulations: Structurally disordered materials continue to pose fundamental questions,\nincluding that of how different disordered phases (\"polyamorphs\") can coexist\nand transform from one to another. As a widely studied case, amorphous silicon\n(a-Si) forms a fourfold-coordinated, covalent random network at ambient\nconditions, but much higher-coordinated, metallic-like phases under pressure.\nHowever, a detailed mechanistic understanding of the liquid-amorphous and\namorphous-amorphous transitions in silicon has been lacking, due to intrinsic\nlimitations of even the most advanced experimental and computational\ntechniques. Here, we show how machine-learning (ML)-driven simulations can\nbreak through this long-standing barrier, affording a comprehensive,\nquantum-accurate, and fully atomistic description of all relevant liquid and\namorphous phases of silicon. Combining a model system size of 100,000 atoms\n(ten-nanometre length scale) with a prediction accuracy of a few meV per atom,\nour simulations reveal a remarkable, three-step transformation sequence for\na-Si under increasing external pressure. First, up to 10-11 GPa, polyamorphic\nlow- and high-density amorphous (LDA and HDA) regions are found to coexist,\nrather than appearing sequentially. Then, we observe a structural collapse into\na distinct, very-high-density amorphous (VHDA) phase at 12-13 GPa, reminiscent\nof the dense liquid but being formed at a much lower temperature. Finally, our\nsimulations indicate the transient nature of this VHDA phase: it rapidly\nnucleates crystallites at 13-16 GPa, ultimately leading to the formation of a\npoly-crystalline, simple-hexagonal structure, consistent with experiments but\nnot seen in earlier simulations.",
        "positive": "Structural transformations of double-walled carbon nanotube bundle under\n  hydrostatic pressure: Three kinds of the response mechanisms to the external pressure have been\nfound for double-walled carbon nanotube (DWNT) bundle, depending strongly on\ntheir average radius and symmetry. The small-diameter DWNT bundle undergoes a\nsmall discontinuous volume change, and then deform continuously. The\nintermediate-diameter DWNT bundle collapses completely after a structure phase\ntransition (SPT). Significantly, two SPTs exist for the larger-diameter DWNT\nbundle if the outer tube has no $C_{6}$ or $C_{3}$ symmetry. It would be\ninteresting to search for signatures of these different structural\ntransformations by experimentally investigating mechanical, optical and thermal\nresponse functions of DWNT bundle."
    },
    {
        "anchor": "Temperature - Pressure phase diagram of the cubic Laves phase Au$_2$Pb: The temperature ($T$) as a function of pressure ($P$) phase diagram is\nreported for the cubic Laves phase compound Au$_2$Pb, which was recently\nproposed to support linearly dispersing \"topological\" bands, together with\nconventional quadratic bands. At ambient pressure, Au$_2$Pb exhibits several\nstructural phase transitions at $T_1$ $=$ 97 K, $T_2$ $=$ 51 K, and $T_3$ $=$\n40 K with superconductivity below $T_{\\rm{c}}$ $=$ 1.2 K. Applied pressure\nresults in a rich phase diagram where $T_1$, $T_2$, and $T_3$ evolve strongly\nwith $P$ and a new phase is stabilized for $P$ $>$ 0.64 GPa that also supports\nsuperconductivity below 1.1 K. These observations suggest that Au$_2$Pb is an\nideal system in which to investigate the relationship between structural\ndegrees of freedom, band topology, and resulting anomalous behaviors.",
        "positive": "Spin-Polarized Electron Injection through an Fe/InAs Junction: We report on the spin-polarized electron injection through an\nFe(100)/InAs(100) junction. The circularly polarized electroluminescence of\ninjected electrons from epitaxially grown Fe thin film into InAs(100) in an\nexternal magnetic field is measured to investigate the spin injection\nefficiency. The obtained polarization of the electroluminescence is seen to\nincrease up to about -12 % at the temperature of 6.5 K and the external\nmagnetic field of 10 T. This result suggests that the efficient spin injection\nis possible through the ferromagnetic metal/semiconductor (FM/SC) interface\nwithout a tunneling barrier despite the contradictory arguments based on\nconductivity mismatch at the FM/SC interface."
    },
    {
        "anchor": "On the bending of rectangular atomic monolayers along different\n  directions: an ab initio study: We study the bending of rectangular atomic monolayers along different\ndirections from first principles. Specifically, choosing the phosphorene, GeS,\nTiS$_3$, and As$_2$S$_3$ monolayers as representative examples, we perform\nKohn-Sham density functional theory calculations to determine the variation in\ntransverse flexoelectric coefficient and bending modulus with the direction of\nbending. We find that while the flexoelectric coefficient is nearly isotropic,\nthere is significant and complex anisotropy in bending modulus that also\ndiffers between the monolayers, with extremal values not necessarily occurring\nalong the principal directions. In particular, the commonly adopted orthotropic\ncontinuum plate model with uniform thickness fails to describe the observed\nvariations in bending modulus for GeS, TiS$_3$, and As$_2$S$_3$. We determine\nthe direction-dependent effective thickness for use in such continuum models.\nWe also show that the anisotropy in bending modulus is not associated with the\nrehybridization of atomic orbitals.",
        "positive": "Persistent type-II multiferroicity in nanostructured MnWO4 ceramics: We show that the type-II multiferroic properties of bulk MnWO4 are kept in\nnanostructured ceramics of 50 nm grain size prepared via spark plasma sintering\n(SPS). This means that ferroelectric polarization is robust against downsizing,\nwhich is at variance with standard ferroelectrics like BaTiO3. We ascribe this\nstability to the spin-driven nature of the ferroe-lectric correlations in\ntype-II multiferroics while it is resulting from lattice distortion in other\ncases. This may open the way for persistent type-II multiferroicity with no\nneed for external stabilization like substrate-generated strain."
    },
    {
        "anchor": "Exciton formation assisted by longitudinal optical phonons in monolayer\n  transition metal dichalcogenides: We examine a mechanism by which excitons are generated via the LO\n(longitudinal optical) phonon-assisted scattering process after optical\nexcitation of monolayer transition metal dichalcogenides. The exciton formation\ntime is computed as a function of the exciton center-of-mass wavevector,\nelectron and hole temperatures, and carrier densities for known values of the\nFr\\\"ohlich coupling constant, LO phonon energy, lattice temperature, and the\nexciton binding energy in layered structures. For the monolayer MoS$_2$, we\nobtain ultrafast exciton formation times on the sub-picosecond time scale at\ncharge densities of 5 $\\times$ 10$^{11}$ cm$^{-2}$ and carrier temperatures\nless than 300 K, in good agreement with recent experimental findings ($\\approx$\n0.3 ps). While excitons are dominantly created at zero center-of-mass\nwavevectors at low charge carrier temperatures ($\\approx$ 30 K), the exciton\nformation time is most rapid at non-zero wavevectors at higher temperatures\n($\\ge $ 120 K) of charge carriers. The results show the inverse square-law\ndependence of the exciton formation times on the carrier density, consistent\nwith a square-law dependence of photoluminescence on the excitation density.\nOur results show that excitons are formed more rapidly in exemplary monolayer\nselenide-based dichalcogenides (MoSe$_2$ and WSe$_2$) than sulphide-based\ndichalcogenides (MoS$_2$ and WS$_2$).",
        "positive": "Colossal magnetoresistive manganite thin films: Mixed-valence perovskite manganites (Re$_{1-x}$A$_{x}$MnO$_{3}$ where Re=rare\nearth, A=alkaline earth) provide a unique opportunity to study the\nrelationships between the structure and the magnetotransport properties due to\nan interplay among charge carriers, magnetic coupling, orbital ordering and\nstructural distortion. This makes these compounds very exciting from both the\nbasic research and from the technological view point. As the technology pursued\nwith these materials requires film growth, extensive studies have been made on\nmaterials synthesis, structural and physical characterization and device\nfabrication. In this article, the results of the different experimental\ntechniques and the effects of the deposition procedure of the manganite thin\nfilms are first reviewed. Second, the relation between the structural and the\nphysical properties mentioned, and the influence of strains discussed.\\\nFinally, possible applications of manganite thin films for spin electronics are\npresented."
    },
    {
        "anchor": "Emerging Two-dimensional Materials: graphene and its other structural\n  analogues: The study of graphene, since its discovery around 2004, is possibly the\nlargest and fastest growing field of research in material science, because of\nits exotic mechanical, thermal, electronic, optical and chemical properties.\nThe studies of graphene have also led to further research in exploring the\nfield of two dimensional (2D) systems in general. For instance, a number of\nother 2D crystals (not based on carbon, e.g., boronitrene, silicone, graphane,\netc.) have been synthesized or predicted theoretically in recent years.\nFurther, theoretical studies have predicted the possibility of other 2D\nhexagonal crystals of Ge, SiC, GeC, AlN, GaN, etc. The properties of these 2D\nmaterials are very different from their bulk. We shall present the general\nexotic properties of graphene like 2D systems followed by our computational\nresults on the structural and electronic properties of some of them.",
        "positive": "Micromechanical analysis of hyperelastic composites with localized\n  damage using a new low-memory Broyden-step-based algorithm: A multiscale (micro-to-macro) analysis is proposed for the prediction of the\nfinite strain behavior of composites with hyperelastic constituents and\nembedded localized damage. The composites are assumed to possess periodic\nmicrostructure and be subjected to a remote field. At the microscale,\nfinite-strain micromechanical analysis based on the homogenization technique\nfor the (intact) composite is employed for the prediction of the effective\ndeformation. At the macroscale, a procedure, based on the representative cell\nmethod and the associated higher-order theory, is developed for the\ndetermination of the elastic field in the damaged composite. The periodic\ncomposite is discretized into identical cells and then reduced to the problem\nof a single cell by application of the discrete Fourier transform. The\nresulting governing equations, interfacial and boundary conditions in the\nFourier transform domain, are solved by employing the higher-order theory in\nconjunction with an iterative procedure to treat the effects of damage and\nmaterial nonlinearity. The initial conditions for the iterative solution are\nobtained using the weakly-nonlinear material limit and a natural fixed-point\niteration. A locally-convergent low-memory Quasi-Newton solver is then\nemployed. A new algorithm for the implementation of the solver is proposed,\nwhich allows storing in the memory directly the vector-function\nhistory-sequence, which may be advantageous for convergence-control based on\nspecific components of the objective vector-function. The strong-form Fourier\ntransform-based approach employed here, in conjunction with the new solver,\nenables to extend the application of the method to nonlinear materials and may\nhave computational efficiency comparable or possibly advantageous to that of\nstandard approaches."
    },
    {
        "anchor": "Nanocrystalline equiatomic CoCrFeNi alloy thin films: Are they single\n  phase fcc?: The bulk quaternary equiatomic CoCrFeNi alloy is studied extensively in\nliterature. Under experimental conditions, it shows a single-phase fcc\nstructure and its physical and mechanical properties are similar to those of\nthe quinary equiatomic CoCrFeMnNi alloy. Many studies in literature have\nfocused on the mechanical properties of bulk nanocrystalline high entropy\nalloys or compositionally complex alloys, and their microstructure evolution\nupon annealing. The thin film processing route offers an excellent alternative\nto form nanocrystalline alloys. Due to the high nucleation rate and high\ndensity of defects in thin films synthesized by sputtering, the kinetics of\nmicrostructure evolution is often accelerated compared to those taking place in\nthe bulk. Here, thin films are used to study the phase evolution in\nnanocrystalline CoCrFeNi deposited on Si/SiO 2 and c-sapphire substrates by\nmagnetron cosputtering from elemental sources. The phases and microstructure of\nthe films are discussed in comparison to the bulk alloy. The main conclusion is\nthat second phases can form even at room temperature provided there are\nsufficient nucleation sites.",
        "positive": "The Mn site in Mn-doped Ga-As nanowires: an EXAFS study: We present an EXAFS study of the Mn atomic environment in Mn-doped GaAs\nnanowires. Mn doping has been obtained either via the diffusion of the Mn used\nas seed for the nanowire growth or by providing Mn during the growth of\nAu-induced wires. As a general finding, we observe that Mn forms chemical bonds\nwith As but is not incorporated in a substitutional site. In Mn-induced GaAs\nwires, Mn is mostly found bonded to As in a rather disordered environment and\nwith a stretched bond length, reminiscent of that exhibited by MnAs phases. In\nAu-seeded nanowires, along with stretched Mn-As coordination we have found the\npresence of Mn in a Mn-Au intermetallic compound."
    },
    {
        "anchor": "Mechanisms of doping graphene: We distinguish three mechanisms of doping graphene. Density functional theory\nis used to show that electronegative molecule like F4-TCNQ and electropositive\nmetals like K dope graphene p- and n-type respectively. These dopants are\nexpected to lead to a decrease in carrier mobility arising from Coulomb\nscattering but without any hysteresis effects. Secondly, a novel doping\nmechanism is exhibited by Au which dopes bilayer graphene but not single layer.\nThirdly, electrochemical doping is effected by redox reactions and can result\nin p-doping by humid atmospheres and n-doping by NH3 and toluene.",
        "positive": "Ab initio property characterisation of thousands of previously unknown\n  2D materials: We perform extensive density functional theory (DFT) calculations to\ndetermine the stability and elementary properties of 4249 previously unexplored\nmonolayer crystals. The monolayers comprise the most stable subset (energy\nwithin 0.1 eV/atom of the convex hull) of a larger portfolio of two-dimensional\n(2D) materials recently discovered using a deep generative model and systematic\nlattice decoration schemes. The relaxed 2D structures are run through the basic\nproperty workflow of the Computational 2D Materials Database (C2DB) to evaluate\nthe dynamical stability and obtain the stiffness tensor, piezoelectric tensor,\ndeformation potentials, Born and Bader charges, electronic band structure,\neffective masses, plasma frequency, Fermi surface, projected density of states,\nmagnetic moments, magnetic exchange couplings, magnetic anisotropy, topological\nindices, optical- and infrared polarisability. We provide statistical overviews\nof the property data and highlight a few specific examples of interesting\nmaterials. Our work exposes previously unknown parts of the 2D chemical space\nand provides a basis for the discovery of 2D materials with specific\nproperties. All data is available in the C2DB."
    },
    {
        "anchor": "Noise reduction in heat-assisted magnetic recording by optimizing a\n  high/low Tc bilayer structure: It is assumed that heat-assisted magnetic recording (HAMR) is the recording\ntechnique of the future. For pure hard magnetic grains in high density media\nwith an average diameter of $5$nm and a height of $10$nm the switching\nprobability is not sufficiently high for the use in bit-patterned media. Using\na bilayer structure with 50$\\%$ hard magnetic material with low Curie\ntemperature and 50$\\%$ soft magnetic material with high Curie temperature to\nobtain more than 99.2$\\%$ switching probability, leads to very large jitter. We\npropose an optimized material composition to reach a switching probability of\n$P_{\\mathrm{switch}}>99.2\\%$ and simultaneously achieve the narrow transition\njitter of pure hard magnetic material. Simulations with a continuous laser spot\nwere performed with the atomistic simulation program VAMPIRE for a single\ncylindrical recording grain with a diameter of 5nm and a height of 10nm.\nDifferent configurations of soft magnetic material and different amounts of\nhard and soft magnetic material were tested and discussed. Within our analysis,\na composition with 20$\\%$ soft magnetic and $80\\%$ hard magnetic material\nreaches the best results with a switching probability\n$P_{\\mathrm{switch}}>99.2\\%$, an off-track jitter parameter\n$\\sigma_{\\mathrm{off},80/20}=14.2$K and a down-track jitter parameter\n$\\sigma_{\\mathrm{down},80/20}=0.49$nm.",
        "positive": "Localization of electronic states in III-V semiconductor alloys: a\n  comparative study: Electronic properties of III-V semiconductor alloys are examined using first\nprinciples with the focus on the spatial localization of electronic states. We\ncompare localization at the band edges due to various isovalent impurities in a\nhost GaAs including its impact on the photoluminescence line widths and carrier\nmobilities. The extremity of localization at the band edges is correlated with\nthe ability of individual elements to change the band gap and the relative band\nalignment. Additionally, the formation energies of substitutional defects are\ncalculated and linked to challenges associated with the growth and formability\nof alloys. A spectrally-resolved inverse participation ratio is used to map\nlocalization in prospective GaAs-based materials alloyed with B, N, In, Sb, and\nBi for 1.55 $\\mu$m wavelength telecommunication lasers. This analysis is\ncomplemented by a band unfolding of the electronic structure and discussion of\nimplications of localization on the optical gain and Auger losses.\nCorrespondence with experimental data on broadening of the photoluminescence\nspectrum and charge carrier mobilities show that the localization\ncharacteristics can serve as a guideline for engineering of semiconductor\nalloys."
    },
    {
        "anchor": "Multiple-photon excitation of nitrogen vacancy center in diamond: We report the first observation of multi-photon photoluminescence excitation\n(PLE) below the resonant energies of nitrogen vacancy (NV) centers in diamond.\nThe quadratic and cubic dependence of the integrated fluorescence intensity as\na function of excitation power indicate a two-photon excitation pathway for the\nNV- charge state and a three-photon process involved for the neutral NV0 charge\nstate respectively. Comparing the total multi-photon energy with its\nsingle-photon equivalent, the PLE spectra follows the absorption spectrum of\nsingle photon excitation. We also observed that the efficiency of\nphotoluminescence for different charge states, as well as the decay time\nconstant, was dependent on the excitation wavelength and power.",
        "positive": "Molecular dynamics simulations of nucleation of hexagonal($\u03b4$) and\n  cubic($\u03b1$)-FAPbI$_3$ perovskites from solution: Solar to power conversion certified efficiencies of formamidinium lead iodide\nbased single-junction perovskite solar cell is now 26%, all\nperovskite-perovskite tandem $\\sim$28%, and the perovskite-silicon tandem solar\ncell is $\\sim$34% going beyond gallium arsenide solar cells. Therefore, it is\nnow one of the most promising materials for generating cheaper sunlight-based\nelectricity. This material has two commonly known polymorphs; one is a\nthermodynamically stable yellow hexagonal phase. The other one is a metastable\nblack perovskite phase: a powerful photo-active material. Thousands of\nexperiments have been performed to produce the highly crystalline photoactive\nphase of formamidinium lead iodide. Despite that, PSCs often suffer from poor\nreproducibility and stability. One of the root cause is the lack of control\nover their synthesis, i.e. crystallization process, where one of the main\nquests is to synthesize and stabilize corner-sharing defects-free photoactive\nperovskite form of pure or doped black perovskite form of formamidinium lead\niodide and prevent the formation of hexagonal phases. Thus, for the rapid\nindustrialization of perovskite based solar farms to combat global rising\ntemperatures: it is all-important to understand the polymorph selective\nnucleation of formamidinium lead iodide from its precursors. Towards this\nultimate goal, here we perform molecular simulations of the nucleation of\nformamidinium lead iodide from solution. This study aims to take the primary\nsteps for the all-atoms simulations of the polymorph selective crystallization\nof halide perovskites."
    },
    {
        "anchor": "Scale-free statistics of plasticity-induced surface steps on KCl single\n  crystals: Experimental investigations of plastic flow have demonstrated temporal\nintermittency as deformation proceeds in a series of intermittent bursts with\nscale-free size distribution. In the present investigation, a corresponding\nspatial intermittency is demonstrated for plastic flow of KCl single crystals.\nDeformation bursts lead to large surface steps with a height distribution that\nis consistent with the distribution of strain increments in deformation of\nmicro-columns, and the energy distribution of acoustic emission bursts observed\nin deformation of macroscopic single crystal samples of a wide class of\nmaterials.",
        "positive": "Nanostructured antimony tin oxide synthesized via chemical precipitation\n  method: its characterization and application in humidity sensing: In present investigation we report the synthesis of antimony tin oxide\nnanoparticles via chemical precipitation method. The synthesized material was\ncharacterized using X-ray diffractometer, Scanning Electron Microscope,\nUV-visible absorption spectroscopy. XRD shows the crystalline nature of the\nsynthesized material and the crystallite size was estimated by using\nDebye-Scherer equation and its minimum value was 3 nm. Pelletization of\nsynthesized material was done using hydraulic press machine under uniform\npressure of 616 MPa. Then the pellets were annealed at 200, 400 and 600{\\deg}C.\nFurther each pellet was put in humidity sensing chamber and corresponding\nvariations in resistance with relative humidity (%RH) were measured. The\naverage sensitivity was calculated by taking the average of all sensitivities\nranging from 10 to 90% RH. The average sensitivity of the pellet annealed at\n600{\\deg}C was best among all the sensing pellets and was 2.18 K{\\Omega}/%RH.\nResults were reproducible {\\pm}84% after 2 months."
    },
    {
        "anchor": "Predicted alternative structure for tantalum metal under high pressure\n  and high temperature: First-principles simulations have been performed to investigate the phase\nstability of tantalum metal under high pressure and high temperature (HPHT). We\nsearched its low-energy structures globally using our developed multi-algorithm\ncollaborative (MAC) crystal structure prediction technique. The body-centred\ncubic (bcc) was found to be stable at pressure up to 300 GPa. The previously\nreported $\\omega$ and \\textit{A}15 structures were also reproduced\nsuccessfully. More interestingly, we observed another phase (space group:\n\\textit{Pnma}, 62) that is more stable than $\\omega$ and \\textit{A}15. Its\nstability is confirmed by its phonon spectra and elastic constants. For\n$\\omega$-Ta, the calculated elastic constants and high-temperature phonon\nspectra both imply that it is neither mechanically nor dynamically stable.\nThus, $\\omega$ is not the structure to which bcc-Ta transits before melting. On\nthe contrary, the good agreement of \\textit{Pnma}-Ta shear sound velocities\nwith experiment suggests \\textit{Pnma} is the new structure of Ta implied by\nthe discontinuation of shear sound velocities in recent shock experiment [J.\nAppl. Phys. \\textbf{111}, 033511 (2012)].",
        "positive": "Electronic structure of the Ge/Si(105) hetero-interface: Thin Ge layers deposited on Si(105) form a stable single-domain film\nstructure with large terraces and rebonded-step surface termination, thus\nrealizing an extended and ordered Ge/Si planar hetero-junction. At the coverage\nof four Ge monolayers angle-resolved photoemission spectroscopy reveals the\npresence of two-dimensional surface and film bands displaying energy-momentum\ndispersion compatible with the 5x4 periodicity of the system. The good\nagreement between experiment and first-principles electronic structure\ncalculations confirms the validity of the rebonded-step structural model. The\ndirect observation of surface features within 1 eV below the valence band\nmaximum corroborates previously reported analysis of the electronic and optical\nbehavior of the Ge/Si hetero-interface."
    },
    {
        "anchor": "Metal Oxide Nanoparticles and Their Applications: A Report: Herein, we report a brief introduction of metal oxide nanoparticles and their\ndiverse applications in different scientific and medical fields. This report\nwill be updated frequently to give a complete review in similar fields of\nnanotechnology. In the present version of the report, an introduction to\nnanotechnology and nanomaterials with some synthesis routes (such as\nHydrothermal synthesis and Sol-Gel synthesis etc.) to prepare the metal oxide\nnanoparticles is given. In this version we have primarily included the basic\nintroduction of application of metal oxide nanoparticles in the fields of\nbiomedical, resistive switching and photovoltaic etc.",
        "positive": "Antisymmetry: Fundamentals and Applications: Symmetry is fundamental to understanding our physical world. An antisymmetry\noperation switches between two different states of a trait, such as two\ntime-states, position-states, charge-states, spin-states, chemical-species etc.\nThis review covers the fundamental concepts of antisymmetry, and focuses on\nfour antisymmetries, namely spatial inversion in point groups, time reversal,\ndistortion reversal and wedge reversion. The distinction between classical and\nquantum mechanical descriptions of time reversal is presented. Applications of\nthese antisymmetries in crystallography, diffraction, determining the form of\nproperty tensors, classifying distortion pathways in transition state theory,\nfinding minimum energy pathways, diffusion, magnetic structures and properties,\nferroelectric and multiferroic switching, classifying physical properties in\narbitrary dimensions, and antisymmetry-protected topological phenomena are\npresented."
    },
    {
        "anchor": "Current-driven nucleation and propagation of antiferromagnetic\n  skyrmionium: We present a theoretical study on nucleation and propagation of\nantiferromagnetic skyrmionium induced by spin current injection. A skyrmionium,\nalso known as 2{\\pi} skyrmion, is a vortex-like magnetic structure\ncharacterized by a topological charge, the so-called skyrmion number, being\nzero. We find that an antiferromagnetic skyrmionium can be generated via a\nlocal injection of spin current with toroidal distribution. A spatially uniform\nspin current is then demonstrated to induce a propagation of the skyrmionium.\nWe derive an expression for the skyrmionium velocity based on a\ncollective-coordinate model, which agrees well with our numerical results. Our\nfindings suggest a novel way of nucleating an antiferromagnetic skyrmionium, as\nwell as an analytical estimation of the current-driven skyrmionium velocity.",
        "positive": "Observation of the Spin-Seebeck Effect in a Ferromagnetic Semiconductor: The spin-Seebeck effect was recently discovered in a metallic ferromagnet and\nconsists of a thermally generated spin distribution that is electrically\nmeasured utilizing the inverse spin Hall effect. Here this effect is reproduced\nexperimentally in a ferromagnetic semiconductor, GaMnAs, which allows for\nflexible design of the magnetization directions, a larger spin polarization,\nand measurements across the magnetic phase transition. The spin-Seebeck effect\nin GaMnAs is observed even in the absence of longitudinal charge transport. The\nspatial distribution of spin-currents is maintained across electrical breaks\nhighlighting the local nature of the effect, which is therefore ascribed to a\nthermally induced spin redistribution."
    },
    {
        "anchor": "Nonequilibrium Thermodynamics of Amorphous Materials I: Internal Degrees\n  of Freedom and Volume Deformation: This is the first of three papers devoted to the nonequilibrium\nthermodynamics of amorphous materials. Our focus here is on the role of\ninternal degrees of freedom in determining the dynamics of such systems. For\nillustrative purposes, we study a solid whose internal degrees of freedom are\nvacancies that govern irreversible volume changes. Using this model, we compare\na thermodynamic theory based on the Clausius-Duhem inequality to a statistical\nanalysis based directly on the law of increase of entropy. The statistical\ntheory is used first to derive the the Clausius-Duhem inequality. We then use\nthe theory to go beyond those results and obtain detailed equations of motion,\nincluding a rate factor that is enhanced by deformation-induced noisy\nfluctuations. The statistical analysis points to the need for understanding how\nboth energy and entropy are shared by the vacancies and their environments.",
        "positive": "Origin of the Curie-von Schweidler law and the fractional capacitor from\n  time-varying capacitance: Most dielectrics of practical purpose exhibit memory and are described by the\ncentury-old Curie-von Schweidler law. Interestingly, the Curie-von Schweidler\nlaw is the motivation behind an unconventional circuit component called\nfractional capacitor which due to its power-law property is extensively used in\nthe modeling of complex dielectric media. Unfortunately, the empirical nature\nof the Curie-von Schweidler law plagues the applications of the fractional\ncapacitor. Here, we derive the Curie-von Schweidler law from a series\ncombination of a resistor and a capacitor with a linear time-varying\ncapacitance. This may possibly be its first derivation from physical\nprinciples. However, this required a modification of the classical\ncharge--voltage relation of a capacitor to account for the time-varying\ncapacitance. The limitation of the classical charge-voltage relation and its\nsubsequent modification are justified using appropriate circuit modeling.\nConsequently, the parameters of the Curie-von Schweidler law and the fractional\ncapacitor gain physical interpretation. The Debye response of dielectrics\nemerges naturally from the limiting case of the power-law response at short\ntimescales. The obtained results are validated by matching them with the\npublished experimental reports."
    },
    {
        "anchor": "Remote Surface Roughness Scattering in FDSOI devices with\n  high-$\u03ba$/SiO$_2$ gate stacks: We investigate remote surface scattering (RSR) by the SiO$_2$/HfO$_2$\ninterface in Fully-Depleted Silicon-on-Insulator (FDSOI) devices using\nNon-Equilibrium Green's Functions. We show that the RSR mobility is controlled\nby cross-correlations between the surface roughness profiles at the Si/SiO$_2$\nand SiO$_2$/HfO$_2$ interfaces. Therefore, surface roughness and remote surface\nroughness can not be modeled as two independent mechanisms. RSR tends to\nenhance the total mobility when the Si/SiO$_2$ interface and SiO$_2$ thickness\nprofiles are correlated, and to decrease the total mobility when they are\nanti-correlated. We discuss the implications for the high-$\\kappa$/Metal gate\ntechnologies.",
        "positive": "High thermoelectric efficiency in monolayer PbI$_2$ from 300 K to 900 K: By using a first-principles approach, monolayer PbI$_2$ is found to have\ngreat potential in thermoelectric applications. The linear Boltzmann transport\nequation is applied to obtain the perturbation to the electron distribution by\ndifferent scattering mechanisms. The mobility is mainly limited by the\ndeformation-potential interaction with long-wavelength acoustic vibrations at\nlow carrier concentrations. At high concentrations, ionized impurity scattering\nbecomes stronger. The electrical conductivity and Seebeck coefficient are\ncalculated accurately over various ranges of temperature and carrier\nconcentration. The lattice thermal conductivity of PbI$_2$, 0.065 W/mK at 300\nK, is the lowest among other 2D thermoelectric materials. Such ultralow thermal\nconductivity is attributed to large atomic mass, weak interatomic bonding,\nstrong anharmonicity, and localized vibrations in which the vast majority of\nheat is trapped. These electrical and phonon transport properties enable high\nthermoelectric figure of merit over 1 for both p-type and n-type doping from\n300 K to 900 K. A maximum $zT$ of 4.9 is achieved at 900 K with an electron\nconcentration of 1.9$\\times$10$^{12}$ cm$^{-2}$. Our work shows exceptionally\ngood thermoelectric energy conversion efficiency in monolayer PbI$_2$, which\ncan be integrated to the existing photovoltaic devices."
    },
    {
        "anchor": "Kinetics of grain-boundary nucleated transformations in rectangular\n  geometries and one paradox relating to Cahn's model: Volume-fraction expressions are obtained for the systems of an infinite\nnumber of parallel planes arranged both regularly and randomly. As a special\ncase of random arrangement, a non-Poissonian point process (the second-order\nErlang process) of arrangement of planes is considered for the first time. The\nexact volume-fraction expression obtained for this case shows that it cannot be\nderived by the Cahn method, i. e. the extended-volume approach is applicable\nonly to Poisson processes. The volume fraction equations for regular planes are\nused to study cubic grain structures, both regular and random. It is shown that\nthe Cahn equation underestimates the transformation kinetics in both regular\nand random structures with four different size distributions of cubes; the\ndegree of underestimation depends on the size distribution, being the largest\nin the regular structure. The paradox of packing is described: the structures\ncomposed of the same elements (random parallelepipeds) transforming in the same\nway, but packed differently, give different transformation rates.",
        "positive": "Pressure induced evolution of band structure in black phosphorus studied\n  by $^{31}$P-NMR: Two-dimensional layered semiconductor black phosphorus (BP), a promising\npressure induced Dirac system as predicted by band structure calculations, has\nbeen studied by $^{31}$P-nuclear magnetic resonance. Band calculations have\nbeen also carried out to estimate the density of states $D(E)$. The temperature\nand pressure dependences of nuclear spin lattice relaxation rate $1/T_1$ in the\nsemiconducting phase are well reproduced using the derived $D(E)$, and the\nresultant pressure dependence of semiconducting gap is in good accordance with\nprevious reports, giving a good confirmation that the band calculation on BP is\nfairly reliable. The present analysis of $1/T_1$ data with the complemental\ntheoretical calculations allows us to extract essential information, such as\nthe pressure dependences of $D(E)$ and chemical potential, as well as to\ndecompose observed $1/T_1$ into intrinsic and extrinsic contributions. An\nabrupt increase in $1/T_1$ at 1.63GPa indicates that the semiconducting gap\ncloses, resulting in an enhancement of conductivity."
    },
    {
        "anchor": "A Comparison of Genetic Algorithms and Simulated Annealing in Maximizing\n  the Thermal Conductivity of Discrete Massive Chains: Functions of chemical composition are complex and discrete in nature making\nit impossible to optimize them with gradient methods. Genetic algorithms, which\ndo not use derivative information, are used to maximize the thermal\nconductivity of one-dimensional classical harmonic oscillators made from a\nfixed library of randomly generated molecular units. The ability for the\ngenetic algorithm to build structures with components having no physical\nincrement is important in optimizing molecules with a library of unrelated\npolymer units. The performance of genetic algorithms in this problem is\ncompared with simulated annealing. Hyper-parameters for these routines are\nselected from a grid search in order to optimize their expected solution\nstrength. The solutions found via the genetic algorithm consistently outperform\nthose of simulated annealing at the cost of longer computer time. Together,\nthese algorithms are able to find thermal conductor candidates that mirror\nsolutions in continuous media.",
        "positive": "Surface-Sensitive Raman Scattering by Transferable Nanoporous Plasmonic\n  Membranes: Raman spectroscopy is a powerful technique to characterize materials. It\nprobes non-destructively chemical composition, crystallinity, defects, strain\nand coupling phenomena. However, the Raman response of surfaces or thin films\nis often weak and obscured by dominant bulk signals. Here we overcome this\nlimitation by placing a transferable porous gold membrane (PAuM) on top of the\nsurface of interest. Slot-like nanopores in the membrane act as plasmonic slot\nantennas and enhance the Raman response of the surface or thin film underneath.\nSimultaneously, the PAuM suppresses the penetration of the excitation laser\ninto the bulk, efficiently blocking the bulk Raman signal. Using graphene as a\nmodel surface, we show that these two simultaneous effects lead to an increase\nin the surface-to-bulk Raman signal ratio by three orders of magnitude. We find\nthat 90% of the Raman enhancement occurs within the top 2.5 of the material,\ndemonstrating truly surface-sensitive Raman scattering. To validate our\napproach, we analyze the surface of a LaNiO3 thin film. We observe a Raman mode\nsplitting for the LaNiO3 surface-layer, which is spectroscopic evidence that\nthe surface structure differs from the bulk. This result underpins that PAuM\ngive direct access to Raman signatures of surfaces and their structural\nproperties."
    },
    {
        "anchor": "Raman micro-spectroscopy as a tool to measure the absorption coefficient\n  and the erosion rate of hydrogenated amorphous carbon films heat-treated\n  under hydrogen bombardment: We present a fast and simple way to determine the erosion rate and absorption\ncoefficient of hydrogenated amorphous carbon films exposed to a hydrogen atomic\nsource based on ex-situ Raman micro-spectroscopy. Results are compared to\nellipsometry measurement. The method is applied to films eroded at different\ntemperatures. A maximum of the erosion rate is found at ~ 450 {\\degree}C in\nagreement with previous results. This technique is suitable for future\nquantitative studies on the erosion of thin carbonaceous films, especially of\ninterest for plasma wall interactions occurring in thermonuclear fusion\ndevices.",
        "positive": "Physical characteristics and cation distribution of NiFe2O4 thin films\n  with high resistivity prepared by reactive co-sputtering: We fabricated NiFe2O thin films on MgAl2O4 (001) substrates by reactive dc\nmagnetron co-sputtering in a pure oxygen atmosphere at different substrate\ntemperatures. The film properties were investigated by various techniques with\na focus on their structure, surface topography, magnetic characteristics, and\ntransport properties. Structural analysis revealed a good crystallization with\nepitaxial growth and low roughness and a similar quality as in films grown by\npulsed laser deposition. Electrical conductivity measurements showed high room\ntemperature resistivity (12 Ohmm), but low activation energy, indicating an\nextrinsic transport mechanism. A band gap of about 1.55 eV was found by optical\nspectroscopy. Detailed x-ray spectroscopy studies confirmed the samples to be\nferrimagnetic with fully compensated Fe moments. By comparison with multiplet\ncalculations of the spectra we found that the cation valencies are to a large\nextent Ni2+ and Fe3+."
    },
    {
        "anchor": "The Deposition of High-Quality HfO2 on Graphene and the Effect of Remote\n  Oxide Phonon Scattering: We demonstrate the atomic layer deposition of high-quality HfO2 film on\ngraphene and report the magnitude of remote oxide phonon (ROP) scattering in\ndual-oxide graphene transistors. Top gates with 30 nm HfO2 oxide layer exhibit\nexcellent doping capacity of greater than 1.5x10^(13)/cm^(2). The carrier\nmobility in HfO2-covered graphene reaches 20,000 cm^(2)/Vs at low temperature,\nwhich is the highest among oxide-covered graphene and compares to that of\npristine samples. The temperature-dependent resistivity exhibits the effect of\nROP scattering from both the SiO2 substrate and the HfO2 over-layer. At room\ntemperature, surface phonon modes of the HfO2 film centered at 54 meV dominate\nand limit the carrier mobility to ~20,000 cm^(2)/Vs. Our results highlight the\nimportant choice of oxide in graphene devices.",
        "positive": "Structural Properties and Thermodynamics of Hafnium sub-oxides in RRAM: We study the structural and electronic properties of various hafnium\nsub-oxides HfzO from z = 9 to z = 0.5, by ab initio simulation using Density\nFunctional Theory. The stability of these sub-oxides is studied against\nmonoclinic HfO2. The progressive oxidation of a given HfzO is also envisaged\ntoward stoichiometric HfO2. The analogy with a conductive region of electrons\ninside a HfO2 matrix is discussed within the context of Oxide-based Resistive\nRandom Access Memories (OxRRAM) devices which employ hafnium dioxide as an\ninsulator."
    },
    {
        "anchor": "Role of Magnon-Magnon Scattering in Magnon Polaron Spin Seebeck Effect: The spin Seebeck effect (SSE) signal of magnon polarons in bulk-Y3Fe5O12\n(YIG)/Pt heterostructures is found to drastically change as a function of\ntemperature. It appears as a dip in the total SSE signal at low temperatures,\nbut as the temperature increases, the dip gradually decreases before turning to\na peak. We attribute the observed dip-to-peak transition to the rapid rise of\nthe four-magnon scattering rate. Our analysis provides important insights into\nthe microscopic origin of the hybridized excitations and the overall\ntemperature dependence of the SSE anomalies.",
        "positive": "Structures, Electronic Properties, Spectroscopies and Hexagonal\n  Monolayer Phase of a Family of Unconventional Fullerenes C64X4 (X = H;\n  F;Cl;Br): A systematic first-principles study within density functional theory on the\ngeometrical structures and electronic properties of unconventional fullerene\nC64 and its derivatives C64X4 (X = H; F;Cl;Br) has been performed. By searching\nthrough all 3465 isomers of C64, the ground state of C64 is found to be\nspherical shape with D2 symmetry, which differs from the parent cage of the\nrecently synthesized C64H4 that is pear-shaped with C3v symmetry. We found that\nthe addition of the halogen atoms like F;Cl;Br to the pentagon-pentagon fusion\nvertex of C64 cage could enhance the stability, forming the unconventional\nfullerenes C64X4. The Mulliken charge populations, LUMO-HOMO gap energies and\ndensity of states are calculated, showing that different halogen atoms added to\nC64 will cause remarkably different charge populations of the C64X4 molecule;\nthe chemical deriving could enlarge the energy gaps and affect the electronic\nstructures distinctly. It is unveiled that C64F4 is even more stable than\nC64H4, as the C-X bond energy of the former is higher than that of the latter.\nThe computed spectra of C64H4 molecules agree well with the experimental data;\nthe IR, Raman, NMR spectra of C64X4 (X = F;Cl;Br) are also calculated to\nstimulate further experimental investigations. Finally, it is uncovered by\ntotal energy calculations that C64X4 could form a stable hexagonal monolayer."
    },
    {
        "anchor": "Plasma treatment as an unconventional molecular magnet engineering\n  method: Molecular magnetism aims to design materials with unique properties at the\nmolecular level, focusing on the systematic synthesis of new chemical\ncompounds. In this paper, we propose an alternative route to engineer molecular\nmagnetic materials through plasma irradiation. Our research indicates that the\nlong-range magnetic order temperature in the three-dimensional\n$\\mathrm{\\{[Mn^{II}(H_2O)_2]_2[Nb^{IV}(CN)_8]\\cdot 4H_2O\\}_n}$ molecular\nferrimagnet increases by 20 K after plasma treatment. The core structure of the\ncompound does not reveal significant changes after plasma processing, as\nconfirmed by the X-ray powder diffraction analysis. The observed results are\nattributed to the release of crystallized water molecules. The described\nprocedure can serve as a viable approach to altering the magnetic properties of\nthe molecular systems.",
        "positive": "Multiferroic oxides-based flash-memory and spin-field-effect transistor: We propose a modified spin-field-effect transistor fabricated in a two\ndimensional electron gas (2DEG) formed at the surface of multiferroic oxides\nwith a transverse helical magnetic order. The topology of the oxide local\nmagnetic moments induces a resonant momentum-dependent effective spin-orbit\ninteraction acting on 2DEG. We show that spin polarization dephasing is\nstrongly suppressed which is crucial for functionality. The carrier spin\nprecession phase depend linearly on the magnetic spiral helicity. The latter is\nelectrically controllable by virtue of the magento-electric effect. We also\nsuggest a flash-memory device based on this structure."
    },
    {
        "anchor": "Piezo- and pyroelectricity in Zirconia: a study with machine learned\n  force fields: The discovery of very large piezo- and pyroelectric effects in ZrO2 and\nHfO2-based thin films opens up new opportunities to develop silicon-compatible\nsensor and actor devices. The effects are amplified close to the\npolar-orthorhombic to tetragonal phase transition temperature. Molecular\ndynamics is the preferred technique to simulate such effects, though its\napplication has to solve the dilemma between sufficient accuracy and sufficient\nefficiency of the interatomic force field. Here we present a deep neural\nnetwork-based interatomic force field of ZrO2 learned from ab initio data using\na systematic learning procedure in the Deep Potential framework. The model\npotential is verified to predict a variety of structural and dynamic properties\nwith an accuracy comparable to density functional theory calculations. Then the\nDeep Potential model is used to reproduce the different thermal expansion and\npiezo and pyroelectric phenomena in ZrO2 with molecular dynamics calculations.\nAt low temperature simulating the direct effect we find negative values for the\npiezo-and pyroelectric coefficients matching the ab initio calculations.\nApproaching the phase transition temperature these values remain negative and\nbecome large. Simulating the field induced effect above the phase transition\ntemperature we find positive, giant piezo-electric coefficients matching the\nobservations. The model is able to explain the large values and the sign of the\nexperimental observations in relation to the polar-orthorhombic to tetragonal\nphase transition. The model furthermore explains the recently observed giant\ndielectric constant in a similiar system.",
        "positive": "Site-specific surface atom valence band structure via X-ray standing\n  wave excited photoemission: X-ray standing wave (XSW) excited photoelectron emission was used to measure\nthe site-specific valence band (VB) for 1/2 monolayer (ML) Pt grown on a SrTiO3\n(001) surface. The XSW induced modulations in the core level (CL) and VB\nphotoemission from the surface and substrate atoms were monitored for three hkl\nsubstrate Bragg reflections. The XSW CL analysis shows the Pt to have an\nfcc-like cube-on-cube epitaxy with the substrate. The XSW VB information\ncompares well to a density functional theory calculated projected density of\nstates from the surface and substrate atoms. Overall, this work represents a\nnovel method for determining the contribution to the density of states by\nvalence electrons from specific atomic surface sites."
    },
    {
        "anchor": "Generation of second harmonic in off-diagonal magneto-impedance in\n  Co-based amorphous ribbons: The off-diagonal magneto-impedance in Co-based amorphous ribbons was measured\nusing a pick-up coil wound around the sample. The ribbons were annealed in air\nor in vacuum in the presence of a weak magnetic field. The evolution of the\nfirst and second harmonics in the pick-up coil voltage as a function of the\ncurrent amplitude was studied. At low current amplitudes, the first harmonic\ndominates in the frequency spectrum of the voltage, and at sufficiently high\ncurrent amplitudes, the amplitude of the second harmonic becomes higher than\nthat of the first harmonic. For air-annealed ribbons, the asymmetric two-peak\nbehaviour of the field dependences of the harmonic amplitudes was observed,\nwhich is related to the coupling between the amorphous phase and surface\ncrystalline layers appearing after annealing. For vacuum-annealed samples, the\nfirst harmonic has a maximum at zero external field, and the field dependence\nof the second harmonic exhibits symmetric two-peak behaviour. The experimental\nresults are interpreted in terms of a quasi-static rotational model. It is\nshown that the appearance of the second harmonic in the pick-up coil voltage is\nrelated to the anti-symmetrical distribution of the transverse field induced by\nthe current. The calculated dependences are in a qualitative agreement with the\nexperimental data.",
        "positive": "Focal-point approach with pair-specific cusp correction for\n  coupled-cluster theory: We present a basis set correction scheme for the coupled-cluster singles and\ndoubles (CCSD) method. The scheme is based on employing frozen natural orbitals\n(FNOs) and diagrammatically decomposed contributions to the electronic\ncorrelation energy that dominate the basis set incompleteness error (BSIE). As\nrecently discussed in [https://doi.org/10.1103/PhysRevLett.123.156401], the\nBSIE of the CCSD correlation energy is dominated by the second-order\nM{\\o}ller-Plesset (MP2) perturbation energy and the particle-particle ladder\nterm. Here, we derive a simple approximation to the BSIE of the\nparticle-particle ladder term that effectively corresponds to a rescaled\npair-specific MP2 BSIE, where the scaling factor depends on the spatially\naveraged correlation hole depth of the coupled-cluster and first-order pair\nwavefunctions. The evaluation of the derived expressions is simple to implement\nin any existing code. We demonstrate the effectiveness of the method for the\nuniform electron gas. Furthermore, we apply the method to coupled-cluster\ntheory calculations of atoms and molecules using FNOs. Employing the proposed\ncorrection and an increasing number of FNOs per occupied orbital, we\ndemonstrate for a test set that rapidly convergent closed and open-shell\nreaction energies, atomization energies, electron affinities, and ionization\npotentials can be obtained. Moreover, we show that a similarly excellent\ntrade-off between required virtual orbital basis set size and remaining BSIEs\ncan be achieved for the perturbative triples contribution to the CCSD(T) energy\nemploying FNOs and the (T*) approximation."
    },
    {
        "anchor": "Polygonization of carbon nanotubes: We use a multiscale procedure to derive a simple continuum model of\nmultiwalled carbon nanotubes that takes into account both strong covalent bonds\nwithin graphene layers and weak bonds between atoms in different layers. The\nmodel predicts polygonization of crossections of large multiwalled nanotubes as\na consequence of their curvature-induced turbostratic structure.",
        "positive": "Dzyaloshinskii-Moriya interaction in absence of spin-orbit coupling: In contrast to conventional assumptions, we show that the\nDzyaloshinskii-Moriya interaction can be of non-relativistic origin, in\nparticular in materials with a non-collinear magnetic configuration, where\nnon-relativistic contributions can dominate over spin-orbit effects. The weak\nantiferromagnetic phase of Mn$_{3}$Sn is used to illustrate these findings.\nUsing electronic structure theory as a conceptual platform, all relevant\nexchange interactions are derived for a general, non-collinear magnetic state.\nIt is demonstrated that non-collinearity influences all three types of exchange\ninteraction and that physically distinct mechanisms, which connect to electron-\nand spin-density and currents, may be used as a general way to analyze and\nunderstand magnetic interactions of the solid state."
    },
    {
        "anchor": "High-pressure X-ray diffraction study on alpha-PbF2: The high-pressure behaviour of alpha-PbF2 has been investigated by\nangular-dispersive synchrotron X-ray powder diffraction up to 6.55(8) GPa. The\nfit of a 3rd-order Birch-Murnaghan equation-of-state gave the volume at zero\npressure V0=194.14(4)\\AA$^3 and the bulk modulus b_0=47.0(6)GPa with the\npressure derivative b'=7.9(4). The continuous-symmetry-measure approach has\nbeen used for the quantification of the distortion of the coordination\npolyhedron in alpha-PbF2 revealing an increasing distortion with pressure.\nkeywords here: high pressure, X-ray diffraction, inorganic compounds PACS:\n61.10.N2, 62.50.+P, 64.20.+t, 07.35, 61.10.-i",
        "positive": "Stripe and short range order in the charge density wave of\n  1T-Cu$_x$TiSe$_2$: We study the impact of Cu intercalation on the charge density wave (CDW) in\n1T-Cu$_{\\text{x}}$TiSe$_{\\text{2}}$ by scanning tunneling microscopy and\nspectroscopy. Cu atoms, identified through density functional theory modeling,\nare found to intercalate randomly on the octahedral site in the van der Waals\ngap and to dope delocalized electrons near the Fermi level. While the CDW\nmodulation period does not depend on Cu content, we observe the formation of\ncharge stripe domains at low Cu content (x$<$0.02) and a breaking up of the\ncommensurate order into 2$\\times$2 domains at higher Cu content. The latter\nshrink with increasing Cu concentration and tend to be phase-shifted. These\nfindings invalidate a proposed excitonic pairing as the primary CDW formation\nmechanism in this material."
    },
    {
        "anchor": "Anisotropic Gilbert damping in perovskite La$_{0.7}$Sr$_{0.3}$MnO$_{3}$\n  thin film: The viscous Gilbert damping parameter governing magnetization dynamics is of\nprimary importance for various spintronics applications. Although, the damping\nconstant is believed to be anisotropic by theories. It is commonly treated as a\nscalar due to lack of experimental evidence. Here, we present an elaborate\nangle dependent broadband ferromagnetic resonance study of high quality\nepitaxial La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ films. Extrinsic effects are suppressed\nand we show convincing evidence of anisotropic damping with twofold symmetry at\nroom temperature. The observed anisotropic relaxation is attributed to the\nmagnetization orientation dependence of the band structure. In addition, we\ndemonstrated that such anisotropy can be tailored by manipulating the stain.\nThis work provides new insights to understand the mechanism of magnetization\nrelaxation.",
        "positive": "Magnetic-field dependence of valley splitting for Si quantum wells grown\n  on tilted SiGe substrates: The valley splitting of the first few Landau levels is calculated as a\nfunction of the magnetic field for electrons confined in a strained silicon\nquantum well grown on a tilted SiGe substrate, using a parameterized\ntight-binding method. For a zero substrate tilt angle, the valley splitting\nslightly decreases with increasing magnetic field. In contrast, the valley\nsplitting for a finite substrate tilt angle exhibits a strong and\nnon-monotonous dependence on the magnetic field strength. The valley splitting\nof the first Landau level shows an exponential increase followed by a slow\nsaturation as the magnetic field strength increases. The valley splitting of\nthe second and third Landau levels shows an oscillatory behavior. The\nnon-monotonous dependence is explained by the phase variation of the Landau\nlevel wave function along the washboard-like interface between the tilted\nquantum well and the buffer material. The phase variation is the direct\nconsequence of the misorientation between the crystal axis and the confinement\ndirection of the quantum well. This result suggests that the magnitude of the\nvalley splitting can be tuned by controlling the Landau-level filling factor\nthrough the magnetic field and the doping concentration."
    },
    {
        "anchor": "High order model for describing the pattern formation processes on\n  semiconductor surfaces: The self-organization processes of nanopattern formation on semiconductor\nsurfaces under low energy ion beam bombardment is considered. The new\nmathematical model based on nonlinear evolution equation of the sixth order is\npresented. The pseudo--spectral method for periodic boundary value problem for\nthis equation is discussed. The influence of high order terms on the evolution\nof the semiconductor surface morphology is studied.",
        "positive": "A new LEED Instrument for Quantitative Spot Profile Analysis: A new instrument for spot profile analysis of electron diffraction - SPA-LEED\n- has been set up. The instrument works either with a transparent phosphor\nscreen for visual inspection of the pattern or in its main mode with a\nchanneltron for the measurement of the intensity. The diffraction pattern is\nrecorded with a fixed channeltron position by scanning the beam over the\nchanneltron aperture using two sets of electrostatic deflection plates. The\nscanning range covers about 30{\\deg}. The intensity may vary over five orders\nof magnitude. The SPA-LEED system was checked with the Si 111 7 x 7 surface. A\nfull width at half maximum of 0.3% of the normal reflex distance corresponding\nto a transfer width of 110 nm is reproducibly obtained. Under optimum\nconditions the transfer width rose up to about 200 nm. Initial high resolution\nmeasurements have been performed on the system Pb on Cu 111. The results\ndemonstrate the possibilities of the new instrument for qualitative and\nquantitative analysis."
    },
    {
        "anchor": "Magnetization and spin dynamics of the spin S=1/2 hourglass nanomagnet\n  Cu5(OH)2(NIPA)4*10H2O: We report a combined experimental and theoretical study of the spin S=1/2\nnanomagnet Cu5(OH)2(NIPA)4*10H2O (Cu5-NIPA). Using thermodynamic, electron spin\nresonance and 1H nuclear magnetic resonance measurements on one hand, and ab\ninitio density-functional band-structure calculations, exact diagonalizations\nand a strong coupling theory on the other, we derive a microscopic magnetic\nmodel of Cu5-NIPA and characterize the spin dynamics of this system. The\nelementary five-fold Cu2+ unit features an hourglass structure of two\ncorner-sharing scalene triangles related by inversion symmetry. Our microscopic\nHeisenberg model comprises one ferromagnetic and two antiferromagnetic exchange\ncouplings in each triangle, stabilizing a single spin S=1/2 doublet ground\nstate (GS), with an exactly vanishing zero-field splitting (by Kramer's\ntheorem), and a very large excitation gap of \\Delta~68 K. Thus, Cu5-NIPA is a\ngood candidate for achieving long electronic spin relaxation (T1) and coherence\n(T2) times at low temperatures, in analogy to other nanomagnets with low-spin\nGS's. Of particular interest is the strongly inhomogeneous distribution of the\nGS magnetic moment over the five Cu2+ spins. This is a purely\nquantum-mechanical effect since, despite the non-frustrated nature of the\nmagnetic couplings, the GS is far from the classical collinear ferrimagnetic\nconfiguration. Finally, Cu5-NIPA is a rare example of a S=1/2 nanomagnet\nshowing an enhancement in the nuclear spin-lattice relaxation rate 1/T1 at\nintermediate temperatures.",
        "positive": "Annealing shallow Si/SiO$_2$ interface traps in electron-beam irradiated\n  high-mobility metal-oxide-silicon transistors: Electron-beam (e-beam) lithography is commonly used in fabricating\nmetal-oxide-silicon (MOS) quantum devices but creates defects at the Si/SiO$_2$\ninterface. Here we show that a forming gas anneal is effective at removing\nshallow defects ($\\leq$ 4 meV below the conduction band edge) created by an\ne-beam exposure by measuring the density of shallow electron traps in two sets\nof high-mobility MOS field-effect transistors (MOSFETs). One set was irradiated\nwith an electron-beam (10 keV, 40 $\\mu$C/cm$^2$) and was subsequently annealed\nin forming gas while the other set remained unexposed. Low temperature (335 mK)\ntransport measurements indicate that the forming gas anneal recovers the e-beam\nexposed sample's peak mobility (14,000 cm$^2$/Vs) to within a factor of two of\nthe unexposed sample's mobility (23,000 cm$^2$/Vs). Using electron spin\nresonance (ESR) to measure the density of shallow traps, we find that the two\nsets of devices are nearly identical, indicating the forming gas anneal is\nsufficient to anneal out shallow defects generated by the e-beam exposure.\nFitting the two sets of devices' transport data to a percolation transition\nmodel, we extract a T=0 percolation threshold density in quantitative agreement\nwith our lowest temperature ESR-measured trap densities."
    },
    {
        "anchor": "Evolution of the electronic structure of ultrathin MnBi2Te4 Films: Ultrathin films of intrinsic magnetic topological insulator MnBi2Te4 exhibit\nfascinating quantum properties such as quantum anomalous Hall effect and axion\ninsulator state. In this work, we systematically investigate the evolution of\nthe electronic structure of MnBi2Te4 thin films. With increasing film\nthickness, the electronic structure changes from an insulator-type with a large\nenergy gap to one with in-gap topological surface states, which is, however,\nstill drastically different from the bulk material. By surface doping of\nalkali-metal atoms, a Rashba split band gradually emerges and hybridizes with\ntopological surface states, which not only reconciles the puzzling difference\nbetween the electronic structures of the bulk and thin film MnBi2Te4 but also\nprovides an interesting platform to establish Rashba ferromagnet that is\nattractive for (quantum) anomalous Hall effect. Our results provide important\ninsights into the understanding and engineering of the intriguing quantum\nproperties of MnBi2Te4 thin films.",
        "positive": "Crystal and Magnetic Structure of Polar Oxide HoCrWO$_6$: Polar magnetic oxide HoCrWO$_6$ is synthesized and its crystal structure,\nmagnetic structure, and thermodynamic properties are investigated. HoCrWO$_6$\nforms the polar crystal structure (space group Pna2$_1$ (#33)) due to the\ncation ordering of W$^{6+}$ and Cr$^{3+}$. There is an antiferromagnetic\ntransition at TN = 24.5 K along with the magnetic entropy change (~5\nJ.Kg.$^{-1}$K$^{-1}$ at 70 kOe). Neutron diffraction measurement indicates that\nboth Cr and Ho sublattices are ordered with the moment of 2.32(5)$\\mu_B$ and\n8.7(4)$\\mu_B$ at 2 K, respectively. While Cr forms A-type collinear\nantiferromagnetic (AFM) structure with magnetic moment along the $b$ axis, Ho\nsublattice orders in a non-coplanar AFM arrangement. A comparison with\nisostructural DyFeWO$_6$ and DyCrWO$_6$ indicates that the magnetic structure\nof this family of compounds is controlled by the presence or absence of eg\nelectrons in the transition metal sublattice."
    },
    {
        "anchor": "Crystallographic reconstruction study of the effects of finish rolling\n  temperature on the variant selection during bainite transformation in C-Mn\n  high-strength steels: The effect of finish rolling temperature (FRT) on the austenite- ()\nto-bainite () phase transformation is quantitatively investigated in\nhigh-strength C-Mn steels. In particular, the present study aims to clarify the\nrespective contributions of the conditioning during the hot rolling and the\nvariant selection (VS) during the phase transformation to the inherited\ntexture. To this end, an alternative crystallographic reconstruction procedure,\nwhich can be directly applied to experimental electron backscatter diffraction\n(EBSD) mappings, is developed by combining the best features of the existing\nmodels: the orientation relationship (OR) refinement, the local pixel-by-pixel\nanalysis and the nuclei identification and spreading strategy. The\napplicability of this method is demonstrated on both quenching and partitioning\n(Q&P) and as-quenched lath-martensite steels. The results obtained on the C-Mn\nsteels confirm that the sample finish rolled at the lowest temperature\n(829{\\deg}C) exhibits the sharpest transformation texture. It is shown that\nthis sharp texture is exclusively due to a strong VS from parent brass\n{110}<1-12>, S {213}<-3-64> and Goss {110}<001> grains, whereas the VS from the\ncopper {112}<-1-11> grains is insensitive to the FRT. In addition, a\nstatistical VS analysis proves that the habit planes of the selected variants\ndo not systematically correspond to the predicted active slip planes using the\nTaylor model. In contrast, a correlation between the Bain group to which the\nselected variants belong and the FRT is clearly revealed, regardless of the\nparent orientation. These results are discussed in terms of polygranular\naccommodation mechanisms, especially in view of the observed development in the\nhot-rolled samples of high-angle grain boundaries with misorientation axes\nbetween <111> and <110> .",
        "positive": "GHz guided optomechanics in planar semiconductor microcavities: Hybrid opto, electro, and mechanical systems operating at several GHz offer\nextraordinary opportunities for the coherent control of opto-electronic\nexcitations down to the quantum limit. We introduce here a monolithic platform\nfor GHz semiconductor optomechanics based on electrically excited phonons\nguided along the spacer of a planar microcavity (MC) embedding quantum well\n(QW) emitters. The MC spacer bound by cleaved lateral facets acts as an\nembedded acoustic waveguide (WG) cavity with a high quality factor\n($Q\\sim10^5$) at frequencies well beyond 6~GHz, along which the acoustic modes\nlive over tens of $\\mu$s. The strong acoustic fields and the enhanced\noptomechanical coupling mediated by electronic resonances induce a huge\nmodulation of the energy (in the meV range) and strength (over 80\\%) of the QW\nphotoluminescence (PL), which, in turn, becomes a sensitive local phonon probe.\nFurthermore, we show the coherent coupling of acoustic modes at different\nsample depths, thus opening the way for phonon-mediated coherent control and\ninterconnection of three-dimensional epitaxial nanostructures."
    },
    {
        "anchor": "CPP Magnetoresistance of Magnetic Multilayers: A critical review: We present a comprehensive review of data and analysis of Giant (G)\nMagnetoresistance (MR) with Current-flow Perpendicular-to-layer-Planes (CPP-MR)\nof magnetic multilayers [F/N]n (n = number of repeats) with alternating\nnanoscale layers of ferromagnetic (F) and non-magnetic (N) metals. GMR, a large\nchange in resistance when an applied magnetic field changes the moment ordering\nof adjacent F-layers from anti-parallel (AP) to parallel (P), was discovered in\n1988 in the Current-flow-in-layer-Planes (CIP) geometry. The CPP-MR has two\nadvantages over the CIP-MR: (1) it allows more direct access to the underlying\nphysics; and (2) it is usually larger, which should be advantageous for\ndevices. When the first CPP-MR data were published in 1991, it was not clear\nwhether electronic transport in GMR multilayers is fully diffusive or at least\npartly ballistic. It was not known whether the properties of layers and\ninterfaces would vary with layer thickness or number. It was not known if the\nCPP-MR would be dominated by scattering within the F-metals or at the F/N\ninterfaces. Nothing was known about: (1) spin-flipping within F-metals,\ncharacterized by a spin-diffusion length, l(F)sf; (2) interface specific\nresistances (AR = area A times resistance R) for N1/N2 interfaces; (3)\ninterface specific resistances and spin-dependent scattering asymmetry at F/N\nand F1/F2 interfaces; and (4) spin-flipping at F/N, F1/F2 and N1/N2 interfaces.\nKnowledge of spin-dependent scattering asymmetries in F-metals and F-alloys,\nand of spin-flipping in N-metals and N-alloys was limited. We show how CPP-MR\nmeasurements have quantified the scattering and spin-flipping parameters that\ndetermine CPP-MR for a wide range of F- and N-metals and alloys and of F/N\npairs. We also review progress in finding techniques and F-alloys and F/N pairs\nto enhance the CPP-MR to make it more competitive for devices.",
        "positive": "Experimental validation of a broadband pentamode elliptical-shaped cloak\n  for underwater acoustics: In this paper we report the numerical design and experimental validation of a\npentamode cloak for scattering reduction of elliptical targets in underwater\nacoustics. Despite being a well-known theoretical concept, experimental\nvalidations of transformation-based acoustic cloaking for non-axisymmetric\ntargets have been hindered due to the difficulties related to the complexity of\nthe required material distribution. We overcome these by adopting a linear\nquasi-symmetric map defined in elliptic coordinates that allows for the design\nof a pentamode cloak with constant anisotropic elasticity and a scalar\ninhomogeneous density. We then perform the long-wavelength homogenization based\noptimization of unit cells that implement the computed material distribution.\nNumerical validations allow to assess the working range of the designed\nmicrostructure, which depends solely on the ratio between the wavelength and\nthe size of the microstructure, and is thus expressed in terms of the maximum\nnormalized wavenumber \\kappa L_c, being L_c the characteristic length of the\nconsidered unit cell. The influence on the scattering performance of the cloak\nof a pentamode bandgap common to all the cells in the microstructure is also\ndiscussed, finding that it is actually detrimental for the scattering\nreduction. Finally, the specimen is fabricated and experimentally tested over\nthe range 0.45<\\kappa L_c<1.34."
    },
    {
        "anchor": "\\textit{Ab initio} study of interacting lattice vibrations and\n  stabilization of the $\u03b2$-phase in Ni-Ti shape-memory alloy: Lattice dynamical methods used to predict phase-transformations in crystals\ntypically evaluate the harmonic phonon spectra and therefore do not work in\nfrequent and important situations where the crystal structure is unstable in\nthe harmonic approximation, such as the $\\beta$ structure when it appears as a\nhigh-temperature phase of the shape memory alloy (SMA) NiTi. Here it is shown\nby self consistent {\\it ab initio} lattice dynamical calculations (SCAILD) that\nthe critical temperature for the pre-martensitic $R$ to $\\beta$\nphase-transformation in NiTi can be effectively calculated with good accuracy,\nand that the $\\beta$-phase is a result primarily of the stabilizing interaction\nbetween different lattice vibrations.",
        "positive": "Huge quadratic magneto-optical Kerr effect and magnetization reversal in\n  the Co$_2$FeSi Heusler compound: Co$_2$FeSi(100) films with L2$_1$ structure deposited onto MgO(100) were\nstudied exploiting both longitudinal (LMOKE) and quadratic (QMOKE)\nmagneto-optical Kerr effect. The films exhibit a huge QMOKE signal with a\nmaximum contribution of up to 30 mdeg, which is the largest QMOKE signal in\nreflection that has been measured thus far. This large value is a fingerprint\nof an exceptionally large spin-orbit coupling of second or higher order. The\nCo$_2$FeSi(100) films exhibit a rather large coercivity of 350 and 70 Oe for\nfilm thicknesses of 22 and 98 nm, respectively. Despite the fact that the films\nare epitaxial, they do not provide an angular dependence of the anisotropy and\nthe remanence in excess of 1% and 2%, respectively."
    },
    {
        "anchor": "Salt-assisted vapor-liquid-solid growth of one-dimensional van der Waals\n  materials: We have combined the benefits of two catalytic growth phenomena to form\nnanostructures of transition metal trichalcogenides (TMTs), materials that are\nchallenging to grow in a nanostructured form by conventional techniques, as\nrequired to exploit their exotic physics. Our growth strategy combines the\nbenefits of vapor-liquid-solid (VLS) growth in controlling dimension and growth\nlocation, and salt-assisted growth for fast growth at moderate temperatures.\nThis salt-assisted VLS growth is enabled through use of a catalyst that\nincludes Au and an alkali metal halide. We demonstrate high yields of NbS3 1D\nnanostructures with sub-ten nanometer diameter, tens of micrometers length, and\ndistinct 1D morphologies consisting of nanowires and nanoribbons with [010] and\n[100] growth orientations, respectively. We present strategies to control the\ngrowth location, size, and morphology. We extend the growth method to\nsynthesize other TMTs, NbSe3 and TiS3, as nanowires. Finally, we discuss the\ngrowth mechanism based on the relationships we measure between the materials\ncharacteristics (growth orientation, morphology and dimensions) and the growth\nconditions (catalyst volume and growth time). Our study introduces\nopportunities to expand the library of emerging 1D vdW materials and their\nheterostructures with controllable nanoscale dimensions.",
        "positive": "First-Principle Investigations of Carrier Multiplication in Si\n  Nanocrystals: a Short Review: Carrier Multiplication (CM) is a Coulomb-driven non-radiative recombination\nmechanism which leads to the generation of multiple electron-hole pairs after\nabsorption of a single high-energy photon. Recently a new CM process, termed\nspace separated quantum cutting, was introduced to explain a set of new\nexperiments conducted in dense arrays of silicon nanocrystals. The occurrence\nof this effect was hypothesized to generate the formation of Auger unaffected\nmultiexciton configurations constituted by single electron-hole pairs\ndistributed on different interacting naocrystals. In this work we discuss\nab-initio results obtained by our group in the study of CM effects in systems\nof strongly interacting silicon nanocrystals. By solving a set of rate\nequations, we simulate the time evolution of the number of electron-hole pairs\ngenerated in dense arrays of silicon nanocrystals after absorption of high\nenergy photons, by describing the circumstances under which CM dynamics can\nlead to the generation of Auger unaffected multiexciton configurations."
    },
    {
        "anchor": "A quantum perturbative pair distribution for determining interatomic\n  potentials from extended X-ray absorption spectroscopy: In this paper we develop a technique for determining interatomic potentials\nin materials in the quantum regime from single--shell Extended X-ray Absorption\nSpectroscopy (EXAFS) spectra. We introduce a pair distribution function, based\non ordinary quantum time--independent perturbation theory. In the proposed\nscheme, the model potential parameters enter the distribution through a\nfourth--order Taylor expansion of the potential, and are directly refined in\nthe fit of the model signal to the experimental spectrum. We discuss in general\nthe validity of our theoretical framework, namely the quantum regime and\nperturbative treatment, and work out a simple tool for monitoring the\nsensitivity of our theory in determining lattice anharmonicities based on the\nstatistical $F$--test. As an example, we apply our formalism to an EXAFS\nspectrum at the Ag K--edge of AgI at T=77 K. We determine the Ag--I potential\nparameters and find good agreement with previous studies.",
        "positive": "Tuning the Resonance Properties of 2D Carbon Nanotube Networks towards\n  Mechanical Resonator: The capabilities of the mechanical resonator-based nanosensors in detecting\nultra-small mass or force shifts have driven a continuing exploration of the\npalette of nanomaterials for such application purpose. Based on large-scale\nmolecular dynamics simulations, we have assessed the applicability of a new\nclass of carbon nanomaterials for the nanoresonator usage, i.e., the single\nwall carbon nanotube (SWNT) network. It is found that the SWNT networks inherit\nthe excellent mechanical properties from the constituent SWNTs, possessing a\nhigh natural frequency. However, although a high quality factor is suggested\nfrom the simulation results, it is hard to obtain an unambiguous Q-factor due\nto the existence of vibration modes in addition to the dominant mode. The\nnonlinearities resulting from these extra vibration modes are found to exist\nuniformly under various testing conditions including different initial\nactuations and temperatures. Further testing shows that these modes can be\neffectively suppressed through the introduction of axial strain, leading to an\nextremely high quality factor in the order of 109 estimated from the SWNT\nnetwork with 2% tensile strain. Additional studies indicate that the carbon\nrings connecting the SWNTs can also be used to alter the vibrational properties\nof the resulting network. This study suggests that the SWNT network can be a\ngood candidate for the applications as nanoresonators."
    },
    {
        "anchor": "Interplay between local structure and electronic properties on CuO under\n  pressure: The electronic and local structural properties of CuO under pressure have\nbeen investigated by means of X-ray absorption spectroscopy (XAS) at Cu K edge\nand ab-initio calculations, up to 17 GPa. The crystal structure of CuO consists\nof Cu motifs within CuO$_4$ square planar units and two elongated apical Cu-O\nbonds. The CuO$_4$ square planar units are stable in the studied pressure\nrange, with Cu-O distances that are approximately constant up to 5 GPa, and\nthen decrease slightly up to 17 GPa. In contrast, the elongated Cu-O apical\ndistances decrease continuously with pressure in the studied range. An\nanomalous increase of the mean square relative displacement (EXAFS Debye\nWaller, \\sigma$^2$) of the elongated Cu-O path is observed from 5 GPa up to 13\nGPa, when a drastic reduction takes place in \\sigma$^2$. This is interpreted in\nterms of local dynamic disorder along the apical Cu-O path. At higher pressures\n(P>13 GPa), the local structure of Cu$^{2+}$ changes from a 4-fold square\nplanar to a 4+2 Jahn-Teller distorted octahedral ion. We interpret these\nresults in terms of the tendency of the Cu$^{2+}$ ion to form favorable\ninteractions with the apical O atoms. Also, the decrease in Cu-O apical\ndistance caused by compression softens the normal mode associated with the\nout-of-plane Cu movement. CuO is predicted to have an anomalous rise in\npermittivity with pressure as well as modest piezoelectricity in the 5-13 GPa\npressure range. In addition, the near edge features in our XAS experiment show\na discontinuity and a change of tendency at 5 GPa. For P < 5 GPa the evolution\nof the edge shoulder is ascribed to purely electronic effects which also affect\nthe charge transfer integral. This is linked to a charge migration from the Cu\nto O, but also to an increase of the energy band gap, which show a change of\ntendency occurring also at 5 GPa.",
        "positive": "Noncentrosymmetric two-dimensional Weyl semimetals in porous Si/Ge\n  structures: In this work we predict a family of noncentrosymmetric two-dimensional (2D)\nWeyl semimetals composed by porous Ge and SiGe structures. These systems are\nenergetically stable graphenylene-like structures with a buckling,\nspontaneously breaking the inversion symmetry. The nontrivial topological phase\nfor these 2D systems occurs just below the Fermi level, resulting in\nnonvanishing Berry curvature around the Weyl nodes. The emerged Weyl semimetals\nare protected by $C_3$ symmetry, presenting one-dimensional edge Fermi-arcs\nconnecting Weyl points with opposite chiralities. Our findings complete the\nfamily of Weyl in condensed-matter physics, by predicting the first\nnoncentrosymmetric class of 2D Weyl semimetals."
    },
    {
        "anchor": "On the Hotspot Problem in Flash Sintering: A perturbation analysis has been conducted to evaluate the generation of\nhotspots inside an electrical loaded ceramic sample, which is assumed to have\nan Arrhenius-type conductivity. The results identified a critical size, above\nwhich a small temperature perturbations will be magnified and hotspots will be\ngenerated. It provides an estimate for the largest sample size suitable for\nflash sintering, beyond which hotspots are likely to form, resulting in\ninhomogeneous heating and sintering.",
        "positive": "Cellular automata inspired multistable origami metamaterials for\n  mechanical learning: Recent advances in multistable metamaterials reveal a link between structural\nconfiguration transition and Boolean logic, heralding a new generation of\ncomputationally capable intelligent materials. To enable higher-level\ncomputation, existing computational frameworks require the integration of\nlarge-scale networked logic gates, which places demanding requirements on the\nfabrication of materials counterparts and the propagation of signals. Inspired\nby cellular automata, we propose a novel computational framework based on\nmultistable origami metamaterials by incorporating reservoir computing, which\ncan accomplish high-level computation tasks without the need to construct a\nlogic gate network. This approach thus eleimates the demanding requirements for\nfabrication of materials and signal propagation when constructing large-scale\nnetworks for high-level computation in conventional mechano-logic. Using the\nmultistable stacked Miura-origami metamaterial as a validation platform, digit\nrecognition is successfully implemented through experiments by a single\nactuator. Moreover, complex tasks, such as handwriting recognition and 5-bit\nmemory tasks, are also shown to be feasible with the new computation framework.\nOur research represents a significant advancement in developing a new\ngeneration of intelligent materials with advanced computational capabilities.\nWith continued research and development, these materials could have a\ntransformative impact on a wide range of fields, from computational science to\nmaterial mechano-intelligence technology and beyond."
    },
    {
        "anchor": "A real-space study of random extended defects in solids : application to\n  disordered Stone-Wales defects in graphene: We propose here a first-principles, parameter free, real space method for the\nstudy of disordered extended defects in solids. We shall illustrate the power\nof the technique with an application to graphene sheets with randomly placed\nStone-Wales defects and shall examine the signature of such random defects on\nthe density of states as a function of their concentration. The technique is\ngeneral enough to be applied to a whole class of systems with lattice\ntranslational symmetry broken not only locally but by extended defects and\ndefect clusters. The real space approach will allow us to distinguish\nsignatures of specific defects and defect clusters.",
        "positive": "Ordering effect on the electrical properties of stoichiometric\n  Ba$_{3}$CaNb$_{2}$O$_{9}$-based perovskite ceramics: Cation ordering is most common process detected in\nA$_{3}$B'B\"$_{2}$O$_{9}$-based complex perovskites. Some important physical\nfeatures of this system are due to the B-site ordering at long and short range.\nFor microwave applications as filters and resonators, the 1:2 order is more\nappropriate. Otherwise, the oxygen vacancies and 1:1 order are considered the\nmain factors behind the good performance of nonstoichiometric\nA$_{3}$B'$_{1+x}$B\"$_{2-x}$O$_{9-\\delta}$-based ceramics as proton conductors.\nUntil now, however, there are no available reports regarding the isolated\neffects of B-site order at long range on the electrical properties of\nstoichiometric systems. This work reports the preparation of 1:1 and 1:2\nfully-ordered Ba$_{3}$CaNb$_{2}$O$_{9}$ ceramics. Here, we combine the Raman\nscattering and group-theory calculations to distinguish the fingerprints of the\n1:1 and 1:2 orders. The electric properties of the ordered\nBa$_{3}$CaNb$_{2}$O$_{9}$ are analyzed in terms of a phenomenological model\nbased on a parallel combination of a resistor, constant phase element, and\ncapacitor. In particular, the conductivity relaxation ascribed to the grain is\ndue to the oxygen vacancies. Besides, we found that the 1:1 order increases the\ndc conductivity, but not enough to account the good performance reported for\nthe non-stoichiometric Ba$_{3}$Ca$_{1+x}$Nb$_{2-x}$O$_{9-\\delta}$-based proton\nconductors."
    },
    {
        "anchor": "Object Kinetic Monte Carlo Simulations of Radiation Damage in\n  Neutron-Irradiated Tungsten Part-I: Neutron Flux with a PKA Spectrum\n  Corresponding to the High-flux Isotope Reactor: Object kinetic Monte Carlo simulations were performed to study the impact of\nvarying dose rate and grain size up to a dose of 1.0 dpa in pure,\npolycrystalline tungsten, subjected to a neutron irradiation having a PKA\nspectrum corresponding to the High Flux Isotope Reactor. The present study\nmodels defect cluster accumulation in tungsten, but does not consider the\nimpact of transmutation or pre-existing defects beyond the grain boundary\nsinks, with varying grain size. With increasing dose rate, the vacancy cluster\ndensity increases, while the number density of vacancies decreases.\nAccordingly, the average vacancy cluster size and the fraction of vacancies\nthat are part of visible clusters decreases with increasing dose rate. With\nincreasing grain size, both the number densities of vacancies and vacancy\nclusters decrease, while both the fraction of vacancies in visible clusters and\nthe average vacancy cluster size increase. This is caused by the\npseudo-ripening of the vacancy clusters due to the longer-lived\nself-interstitial clusters in larger grains. The spatial ordering of vacancy\nclusters along {110} planes was observed for both grain sizes and all dose\nrates studied. Interplanar spacing increases with grain size; however, no clear\ndependence on dose or dose rate was observed. The results of this study show\nthat 1D diffusion of self-interstitial clusters, while necessary, is not\nsufficient to form a void lattice, and that the diffusion of vacancies is also\nrequired. A methodology is suggested for choosing the simulation box dimensions\nso as to represent more faithfully the effects of one-dimensional migrating\nself-interstitial-atom clusters.",
        "positive": "Native defects in hybrid C/BN nanostructures: First-principles calculations of substitutional defects and vacancies are\nperformed for zigzag-edged hybrid C/BN nanosheets and nanotubes which recently\nhave been proposed to exhibit half-metallic properties. The formation energies\nshow that defects form preferentially at the interfaces between graphene and BN\ndomains rather than in the middle of these domains, and that substitutional\ndefects dominate over vacancies. Chemical control can be used to favor\nlocalization of defects at C- B interfaces (nitrogen-rich environment) or C-N\ninterfaces (nitrogen-poor environment). Although large defect concentrations\nhave been considered here (106 cm-1), half-metallic properties can subsist when\ndefects are localized at the C-B interface and for negatively charged defects\nlocalized at the C- N interface, hence the promising magnetic properties\ntheoretically predicted for these zigzag-edged nanointerfaces might not be\ndestroyed by point defects if these are conveniently engineered during\nsynthesis."
    },
    {
        "anchor": "Anhamonic finite temperature effects on the Raman and Infrared spectra\n  to determine the crystal structure phase III of solid molecular hydrogen: We present theoretical calculations of the Raman and IR spectra, as well as\nelectronic properties at zero and finite temperature to elucidate the crystal\nstructure of phase III of solid molecular hydrogen. We find that anharmonic\nfinite temperature are particularly important and qualitatively influences the\nmain conclusions. While P6$_3$/m is the most likely candidate for phase III at\nthe nuclear ground state, at finite temperature the C2/c structure appears to\nbe more suitable.",
        "positive": "Influence of the U3O7 domain structure on cracking during the oxidation\n  of UO2: Cracking is observed when a UO_{2} single crystal is oxidised in air.\nPrevious studies led to the hypothesis that cracking occurs once a critical\ndepth of U_{3}O_{7} oxidised layer is reached. We present some \\mu-Laue X-ray\ndiffraction results, which evidence that the U_{3}O_{7} layer, grown by\ntopotaxy on UO_{2}, is made of domains with different crystalline orientations.\nThis observation was used to perform a modelling of oxidation coupling chemical\nand mechanical parameters, which showed that the domain patterning induces\nstress localisation. This result is discussed in comparison with stress\nlocalisation observed in thin layer deposited on a substrate and used to\npropose an interpretation of UO_{2} oxidation and cracking."
    },
    {
        "anchor": "Confinement of electron holes via the peroxo group formation in the\n  negative charge-transfer materials on the example of SrFeO3: plane-wave\n  density functional theory predictions: The present work puts forward a concept that the thermostable O1s XPS peaks\nwith energy of about 531 eV in negative charge-transfer SrFeO_{3-\\delta}\nperovskite are determined by the peroxo-like oxygen species. The peroxo group\nforms via coupling two oxygen anions coordinated to iron cations with\nd^5\\bar-under{L} (\\bar-under{L}-oxygen electron hole) configuration. By means\nof plane-wave DFT+U approach there have been shown that the peroxo group\nrepresents a metastable state in the absence of oxygen vacancies nearby. The\nO-O bonding confines two electron holes freezing the 3+ oxidation state for two\niron cations bridged by peroxide. Increasing the peroxo group numbers makes the\nferrite a semiconductor with charge-transfer gap of about 0.6 eV.",
        "positive": "Avalanche effects in solid-phase epitaxial crystallization induced by\n  light-ion irradiation: Solid-phase epitaxial crystallization of amorphous Si layers on a crystalline\nSi substrate during B-ion irradiation is investigated over the temperature\nrange 293 - 573 K. Regrowth occurs at all measured temperatures, with\nactivation energy 0.07 eV and prefactor 2.36 nm / 10^14 B cm-2 The low\nactivation energy suggests that free interstitial point defects are involved\nand the unusually large prefactor indicates that each interstitial crystallizes\nabout 50 host Si atoms. We propose that interstitial annihilation at the a/c\ninterface sets off a shock-like process that drives c-Si island nucleation and\ngrowth until terminated by misfit strain."
    },
    {
        "anchor": "Finite size effects on the ultrafast remagnetization dynamics of FePt: We investigate the ultrafast magnetization dynamics of FePt in the L10 phase\nafter an optical heating pulse, as used in heat assisted magnetic recording. We\ncompare continuous and nanogranular thin films and emphasize the impact of the\nfinite size on the remagnetization dynamics. The remagnetization speeds up\nsignificantly with increasing external magnetic field only for the continuous\nfilm, where domain wall motion governs the dynamics. The ultrafast\nremagnetization dynamics in the continuous film are only dominated by heat\ntransport in the regime of high magnetic fields, whereas the timescale required\nfor cooling is prevalent in the granular film for all magnetic field strengths.\nThese findings highlight the necessary conditions for studying the intrinsic\nheat transport properties in magnetic materials.",
        "positive": "First-principles calculations of the spontaneous volume magnetostriction\n  based on the magnetoelastic energy: We present a simple methodology to compute the spontaneous volume\nmagnetostriction with first-principles calculations on the basis of the\nmagnetoelastic energy. This method makes use of deformations of the unit cell\nonly at the ferromagnetic state. Hence, it does not require the difficult\nfirst-principles calculation of the equilibrium volume at the paramagnetic\nstate. To validate this methodology, we apply it to body-centered cubic Fe and\nface-centered cubic Ni single crystals, finding consistent results with\nexperiment and previous first-principles calculations. The simplicity and\nreliability of this approach could be exploited in the high-throughput\nscreening of spontaneous volume magnetostriction, as well as associated\nquantities like isotropic magnetoelastic constants and isotropic\nmagnetostrictive coefficients."
    },
    {
        "anchor": "Improving N\u00e9el domain walls dynamics and skyrmion stability using He\n  ion irradiation: Magnetization reversal and domain wall dynamics in Pt/Co/AlOx trilayers have\nbeen tuned by He+ ion irradiation. Fluences up to 1.5x10$^{15}$ ions/cm$^2$\nstrongly decrease the perpendicular magnetic anisotropy (PMA), without\naffecting neither the spontaneous magnetization nor the strength of the\nDzyaloshinskii-Moriya interaction (DMI). This confirms the robustness of the\nDMI interaction against interfacial chemical intermixing, already predicted by\ntheory. In parallel with the decrease of the PMA in the irradiated samples, a\nstrong decrease of the depinning field is observed. This allows the domain\nwalls to reach large maximum velocities with lower magnetic fields with respect\nto those needed for the pristine films. Decoupling PMA from DMI can therefore\nbe beneficial for the design of low energy devices based on domain wall\ndynamics. When the samples are irradiated with larger He+ fluences, the\nmagnetization gets close to the out-of-plane/in-plane reorientation transition\nwhere 100nm size magnetic skyrmions are stabilized. We observe that as the He+\nfluence increases, the skyrmion size decreases while these magnetic textures\nbecome more stable against the application of an external magnetic field.",
        "positive": "Additive Laser Excitation of Giant Nonlinear Surface Acoustic Wave\n  Pulses: The laser ultrasonics technique perfectly fits the needs for non-contact,\nnon-invasive, non-destructive mechanical probing of samples of mm to nm sizes.\nThis technique is however limited to the excitation of low-amplitude strains,\nbelow the threshold for optical damage of the sample. In the context of strain\nengineering of materials, alternative optical techniques enabling the\nexcitation of high amplitude strains in a non-destructive optical regime are\nseeking. We introduce here a non-destructive method for laser-shock wave\ngeneration based on additive superposition of multiple laser-excited strain\nwaves. This technique enables strain generation up to mechanical failure of a\nsample at pump laser fluences below optical ablation or melting thresholds. We\ndemonstrate the ability to generate nonlinear surface acoustic waves (SAWs) in\nNb:SrTiO$_3$ substrates, at typically 1 kHz repetition rate, with associated\nstrains in the percent range and pressures close to 100 kbars. This study paves\nthe way for the investigation of a host of high-strength SAW-induced phenomena,\nincluding phase transitions in conventional and quantum materials, plasticity\nand a myriad of material failure modes, chemistry and other effects in bulk\nsamples, thin layers, or two-dimensional materials."
    },
    {
        "anchor": "Comparing Forward and Inverse Design Paradigms: A Case Study on\n  Refractory High-Entropy Alloys: The rapid design of advanced materials is a topic of great scientific\ninterest. The conventional, ``forward'' paradigm of materials design involves\nevaluating multiple candidates to determine the best candidate that matches the\ntarget properties. However, recent advances in the field of deep learning have\ngiven rise to the possibility of an ``inverse'' design paradigm for advanced\nmaterials, wherein a model provided with the target properties is able to find\nthe best candidate. Being a relatively new concept, there remains a need to\nsystematically evaluate how these two paradigms perform in practical\napplications. Therefore, the objective of this study is to directly,\nquantitatively compare the forward and inverse design modeling paradigms. We do\nso by considering two case studies of refractory high-entropy alloy design with\ndifferent objectives and constraints and comparing the inverse design method to\nother forward schemes like localized forward search, high throughput screening,\nand multi objective optimization.",
        "positive": "Coherent order parameter dynamics in SmTe$_3$: We present a combined ultrafast optical pump-probe and ultrafast x-ray\ndiffraction measurement of the CDW dynamics in SmTe$_3$ at 300 K. The ultrafast\nx-ray diffraction measurements, taken at the Linac Coherent Light Source reveal\na $\\sim 1.55$ THz mode that becomes overdamped with increasing fluence. We\nidentify this oscillation with the lattice component of the amplitude mode.\nFurthermore, these data allow for a more clear identification of the\nfrequencies present in the optical pump-probe data. In both, reflectivity and\ndiffraction, we observe a crossover of the response from linear (for small\ndisplacements) to quadratic in the amplitude of the order parameter\ndisplacement. Finally, a time-dependent Ginzburg-Landau model captures the\nessential features of the experimental observations."
    },
    {
        "anchor": "Antiferromagnetic insulatronics: spintronics in insulating 3d metal\n  oxides with antiferromagnetic coupling: Antiferromagnetic transition metal oxides are an established and widely\nstudied materials system in the context of spin-based electronics, commonly\nused as passive elements in exchange bias-based memory devices. Currently,\nmajor interest has resurged due to the recent observation of long-distance spin\ntransport, current-induced switching, and THz emission. As a result, insulating\ntransition metal oxides are now considered to be attractive candidates for\nactive elements in novel spintronic devices. Here, we discuss some of the most\npromising materials systems and highlight recent advances in reading and\nwriting antiferromagnetic ordering. This article aims to provide an overview of\nthe current research and potential future directions in the field of\nantiferromagnetic insulatronics.",
        "positive": "Areal density optimizations for heat-assisted-magnetic recording of high\n  density bit-patterned media: Heat-assisted-magnetic recording (HAMR) is hoped to be the future recording\ntechnique for high density storage devices. Nevertheless, there exist several\nrealizations strategies. With a coarse-grained Landau-Lifshitz-Bloch (LLB)\nmodel we investigate in detail benefits and disadvantages of continuous and\npulsed laser spot recording of shingled and conventional bit-patterned media.\nAdditionally we compare single phase grains and bits having a bilayer structure\nwith graded Curie temperature, consisting of a hard magnetic layer with high\n$T_{\\mathrm{C}}$ and a soft magnetic one with low $T_{\\mathrm{C}}$,\nrespectively. To describe the whole write process as realistic as possible a\ndistribution of the grain sizes and Curie temperatures, a displacement jitter\nof the head and the bit positions are considered. For all these cases we\ncalculate bit error rates of various grain patterns, temperatures and write\nhead positions to optimize the achievable areal storage density. Within our\nanalysis shingled HAMR with a continuous laser pulse moving over the medium\nreaches the best results, and thus having the highest potential to become the\nnext generation storage device."
    },
    {
        "anchor": "Phase Transition Mechanism of Hexagonal Graphite to Hexagonal and Cubic\n  Diamond: Ab-initio Simulation: We have performed ab-initio molecular dynamics simulations to elucidate the\nmechanism of the phase transition at high pressure from hexagonal graphite (HG)\nto hexagonal diamond (HD) or to cubic diamond (CD). The transition from HG to\nHD is found to occur swiftly in very small time of 0.2 ps, with large\ncooperative displacements of all the atoms. We observe that alternate layers of\natoms in HG slide in opposite directions by (1/3, 1/6, 0) and (-1/3, -1/6, 0),\nrespectively, which is about 0.7 {\\AA} along the pm[2, 1, 0] direction, while\nsimultaneously puckering by about pm0.25 {\\AA} perpendicular to the a-b plane.\nThe transition from HG to CD occurred with more complex cooperative\ndisplacements. In this case, six successive HG layers slide in pairs by 1/3\nalong [0, 1, 0], [-1, -1, 0] and [1, 0, 0], respectively along with the\npuckering as above. We have also performed calculations of the phonon spectrum\nin HG at high pressure, which reveal soft phonon modes that may facilitate the\nphase transition involving the sliding and puckering of the HG layers. The\nzero-point vibrational energy and the vibrational entropy are found to have\nimportant role in stabilizing HG up to higher pressures (>10 GPa) and\ntemperatures than that estimated (<6 GPa) from previous enthalpy calculations.",
        "positive": "Elastic Properties of Chemical-Vapor-Deposited Monolayer MoS2, WS2, and\n  Their Bilayer Heterostructures: Elastic properties of materials are an important factor in their integration\nin applications. Chemical vapor deposited (CVD) monolayer semiconductors are\nproposed as key components in industrial-scale flexible devices and building\nblocks of 2D van der Waals heterostructures. However, their mechanical and\nelastic properties have not been fully characterized. Here we report high 2D\nelastic moduli of CVD monolayer MoS2 and WS2 (~ 170 N/m), which is very close\nto the value of exfoliated MoS2 monolayers and almost half the value of the\nstrongest material, graphene. The 2D moduli of their bilayer heterostructures\nare lower than the sum of 2D modulus of each layer, but comparable to the\ncorresponding bilayer homostructure, implying similar interactions between the\nhetero monolayers as between homo monolayers. These results not only provide\ndeep insight to understanding interlayer interactions in 2D van der Waals\nstructures, but also potentially allow engineering of their elastic properties\nas desired."
    },
    {
        "anchor": "Analysis of a kink pair model applied to a peierls mechanism in basal\n  and prism plane slips in sapphire deformed between 200C and 1800C: A model based on dislocation glide controlled by the nucleation and\npropagation of kink pairs in a high Peierls stress crystal is revisited and\nmodified to account for changes in dislocation densities and segment lengths\nwith temperature and stress. It is applied to the critical resolved shear\nstress (CRSS) for basal and prism plane slip in sapphire (alpha-Al2O3).\nAccording to agreed-upon knowledge on dislocations in sapphire, basal slip and\nprism plane slip are modelled with undissociated and dissociated dislocations,\nrespectively. In the latter case, partial dislocations move independently.\nAmongst a number of sets of fitting parameters, good fits between experimental\nand modelled CRSS9s are obtained in the long segment limit over the whole range\nof temperatures by making use of physically sound parameters, including a\nstress dependence of the dislocation density.",
        "positive": "Conformational Dynamics Guides Coherent Exciton Migration in Conjugated\n  Polymer Materials: A First-Principles Quantum Dynamical Study: We report on high-dimensional quantum dynamical simulations of\ntorsion-induced exciton migration in a single-chain oligothiophene segment\ncomprising twenty repeat units, using a first-principles parametrized Frenkel\nJ-aggregate Hamiltonian. Starting from an initial inter-ring torsional defect,\nthese simulations provide evidence of an ultrafast two-time scale process at\nlow temperatures, involving exciton-polaron formation within tens of\nfemtoseconds, followed by torsional relaxation on a ~300 femtosecond time\nscale. The second step is the driving force for exciton migration, as initial\nconjugation breaks are removed by dynamical planarization. The quantum coherent\nnature of the elementary exciton migration step is consistent with experimental\nobservations highlighting the correlated and vibrationally coherent nature of\nthe dynamics on ultrafast time scales."
    },
    {
        "anchor": "Magnetoelastic coupling in epitaxial magnetic films: An ab-initio study: A method is developed which allows to determine the first-order and the\nsecond-order magnetoelastic coefficients of a magnetic bulk material from the\nab-initio calculation of the magnetocrystalline anisotropy energy as function\nof a prestrain. Excplicit results are given for bcc Fe, and they agree well\nwith experimental data obtained from the magnetostrictive stress measurements\nfor epitaxial Fe films.",
        "positive": "High-field charge transport and noise in p-Si from first principles: The parameter-free computation of charge transport properties of\nsemiconductors is now routine owing to advances in the ab-initio description of\nthe electron-phonon interaction. Many studies focus on the low-field regime in\nwhich the carrier temperature equals the lattice temperature and the current\npower spectral density (PSD) is proportional to the mobility. The calculation\nof high-field transport and noise properties offers a stricter test of the\ntheory as these relations no longer hold, yet few such calculations have been\nreported. Here, we compute the high-field mobility and PSD of hot holes in\nsilicon from first principles at temperatures of 77 and 300 K and electric\nfields up to 20 kV cm$^{-1}$ along various crystallographic axes. We find that\nthe calculations quantitatively reproduce experimental trends including the\nanisotropy and electric-field dependence of hole mobility and PSD. The\nexperimentally observed rapid variation of energy relaxation time with electric\nfield at cryogenic temperatures is also correctly predicted. However, as in\nlow-field studies, absolute quantitative agreement is in general lacking, a\ndiscrepancy that has been attributed to inaccuracies in the calculated valence\nband structure. Our work highlights the use of high-field transport and noise\nproperties as a rigorous test of the theory of electron-phonon interactions in\nsemiconductors."
    },
    {
        "anchor": "Spin Seebeck effect through antiferromagnetic NiO: We report temperature-dependent spin-Seebeck measurements on Pt/YIG bilayers\nand Pt/NiO/YIG trilayers, where YIG (Yttrium iron garnet, Y$_3$Fe$_5$O$_{12}$)\nis an insulating ferrimagnet and NiO is an antiferromagnet at low temperatures.\nThe thickness of the NiO layer is varied from 0 to 10 nm. In the Pt/YIG\nbilayers, the temperature gradient applied to the YIG stimulates dynamic spin\ninjection into the Pt, which generates an inverse spin Hall voltage in the Pt.\nThe presence of a NiO layer dampens the spin injection exponentially with a\ndecay length of $2 \\pm 0.6$ nm at 180 K. The decay length increases with\ntemperature and shows a maximum of $5.5 \\pm 0.8$ nm at 360 K. The temperature\ndependence of the amplitude of the spin-Seebeck signal without NiO shows a\nbroad maximum of $6.5 \\pm 0.5$ $\\mu$V/K at 20 K. In the presence of NiO, the\nmaximum shifts sharply to higher temperatures, likely correlated to the\nincrease in decay length. This implies that NiO is most transparent to magnon\npropagation near the paramagnet-antiferromagnet transition. We do not see the\nenhancement in spin current driven into Pt reported in other papers when 1-2 nm\nNiO layers are sandwiched between Pt and YIG.",
        "positive": "Sol-gel synthesized double perovskite Gd$_{2}$FeCrO$_{6}$ nanoparticles:\n  Structural, magnetic and optical properties: Lead-free double perovskites are overtaking single perovskites as solar\nharvesting materials due to their superior stability, excellent catalytic\nefficiency and minimal toxicity. In this investigation, we have synthesized\ndouble perovskite Gd$_{2}$FeCrO$_{6}$ (GFCO) nanoparticles for the first time\nvia a facile sol-gel technique to investigate their structural, magnetic and\noptical properties. The double perovskite GFCO crystallized in monoclinic\nstructure with P2$_1$/n space group. The Fe/Cr-O bond length was calculated as\n$\\sim$1.95 angstrom from the Raman spectrum which was consistent with the\nvalue, $\\sim$1.99 angstrom obtained from X-ray diffraction analysis. The\naverage size of the nanoparticles was determined to be $\\sim$70 nm by both\nfield emission scanning electron microscopy and transmission electron\nmicroscopy. The existence of mixed-valence states of Fe and Cr was confirmed by\nX-ray photoelectron spectroscopy. The zero-field cooled (ZFC) and field cooled\n(FC) curves largely diverged below 20 K. A downturn was observed in the ZFC\ncurve at 15 K which corresponds to an antiferromagnetic, N\\'eel transition. The\nnarrow magnetic hysteresis loop recorded at 5 K was nearly saturated and\ndemonstrated an asymmetric shift along the magnetic field axis indicating the\nconcurrence of ferromagnetic and antiferromagnetic domains in GFCO\nnanoparticles. The UV-visible and photoluminescence spectroscopic analyses\nunveiled the semiconducting nature of nanostructured GFCO with an optical band\ngap of 2.0 eV. The as-synthesized thermally stable lead-free GFCO semiconductor\nmight be a potential perovskite material to be employed in photocatalytic and\nrelated solar energy applications due to its ability to absorb the visible\nspectrum of the solar light efficiently"
    },
    {
        "anchor": "Hybrid-Density Functional Theory Study on Band Structures of\n  Tetradymite-Bi2Te3, Sb2Te3, Bi2Se3, and Sb2Se3 Thermoelectric Materials: The low energy band structure near the band gap determines the electrical\nperformance of thermoelectric materials. Here, by using the hybrid-density\nfunctional theory (hybrid-DFT) calculations, we calculate the low energy band\nstructure of Bi2Te3, Sb2Te3, Bi2Se3 and Sb2Se3 in tetradymite phase. We find\nthat the band structure characteristics are very sensitive the selection of the\nexchange energy functional. The predictability of the band gaps and band\ndegeneracies is not enhanced in hybrid-DFT calculations, as compared to DFT\ncalculations. The poor prediction of low energy band structures is originated\nfrom the poor prediction of interlayer distances and the high structure\nsensitivity on the band gap. We conclude that the hybrid DFT calculations are\nnot superior to DFT calculations when predicting band structures of tetradymite\nBi2Te3, Sb2Te3, Bi2Se3 and Sb2Se3 thermoelectric materials.",
        "positive": "Enhanced photocatalytic activation of methane C-H bond by Incorporate\n  Cerium into ETS-10: Ce-ETS-10 was prepared and their ability on photocatalysis coupling of\nmethane has been studied in detail. Ce modification enhanced the photocatalysis\nperformance of ETS-10 on methane conversion reaction, and the methane\nconversion can be carried out under irradiation of visible light. To study the\nvarious rare earth modification to ETS-10, various rare earth elements were\nintroduced to ETS-10 molecular sieve, and the relative photocatalytic methane\nconversion performance were studied. Various characterizations were applied to\nexamine rare earth modification behavior. The SPS results show that the Cerium\nmodification induce visible light photovoltage, which means the strong\nelectron-hole separation which enhance the photocatalytic performance. The\ncharge-hole separation is non-traditional n-n heterojunction for the\ncharge-hole separation is highly oriented and efficient at atomic scale. This\nmechanism shows significant enhancement for methane conversion reaction."
    },
    {
        "anchor": "Influence of interlayer exchange coupling on ultrafast laser-induced\n  magnetization reversal in ferromagnetic spin valves: In this study, we explore the influence of interlayer exchange coupling on\nmagnetization reversal triggered by femtosecond laser pulses in ferromagnetic\nspin valves. Our experiments, focused on femtosecond laser-induced\nmagnetization reversal, methodically vary the thickness of the copper (Cu)\nspacer layer. We identify a critical Cu thickness threshold at 2.32 nm. Above\nthis threshold, a stable reversed magnetic domain is consistently generated\nupon exposure to a single laser pulse. Conversely, with a Cu spacer thinner\nthan 2.32 nm, the observed magnetization reversal from parallel (P) to\nanti-parallel (AP) states occurs only under continuous laser irradiation. Once\nthe laser is stopped, the magnetic configuration relaxes back to its initial P\nstate, influenced by ferromagnetic exchange coupling. This research enhances\nour understanding of the mechanisms that drive optically induced ultrafast\nmagnetization reversal in ferromagnetic spin valves.",
        "positive": "Optical conductivity of an anharmonic large polaron gas at weak coupling: In a polar solid, electrons or other charge carriers can interact with the\nphonons of the ionic lattice, leading to the formation of polaron\nquasiparticles. The optical conductivity and optical absorption spectrum of a\nmaterial are affected by this electron-phonon coupling, most notably leading to\nan absorption peak in the mid-infrared region. Recently, a model Hamiltonian\nfor anharmonic electron-phonon coupling was derived [M. Houtput and J. Tempere,\nPhys. Rev. B \\textbf{103}, 184306 (2021)], that includes both the conventional\nFr\\\"ohlich interaction as well an interaction where an electron interacts with\ntwo phonons simultaneously. In this article, we calculate and investigate the\noptical conductivity of the anharmonic large polaron gas, and show that an\nadditional characteristic absorption peak appears due to this\n1-electron-2-phonon interaction.\n  We calculate a semi-analytical expression for the optical conductivity\n$\\sigma(\\omega)$ at finite temperatures and weak coupling using the Kubo\nformula. The electronic and phononic contributions can be split and treated\nseparately, such that the many-body effects of the electron gas may be taken\ninto account through the well-known dynamical structure factor\n$S(\\mathbf{k},\\omega)$. From the resulting optical conductivity, we calculate\nthe polaron effective mass, an estimate for the electron-phonon scattering\ntimes, and the optical absorption spectrum of the anharmonic polaron gas. We\nshow that alongside the well-known polaron absorption peak at the phonon energy\n$\\hbar \\omega_{\\text{LO}}$, the 1-electron-2-phonon interaction leads to an\nadditional absorption peak at $2 \\hbar \\omega_{\\text{LO}}$. We propose this\nabsorption peak as an experimentally measurable indicator for nonnegligible\n1-electron-2-phonon interaction in a material, since the height of this peak is\nproportional to the strength of this anharmonic interaction."
    },
    {
        "anchor": "Atomization of correlated molecular-hydrogen chain: A fully microscopic\n  Variational Monte-Carlo solution: We discuss electronic properties and their evolution for the linear chain of\n$H_2$ molecules in the presence of a uniform external force $f$ acting along\nthe chain. The system is described by an extended Hubbard model within a fully\nmicroscopic approach. Explicitly, the microscopic parameters describing the\nintra- and inter-site Coulomb interactions are determined together with the\nhopping integrals by optimizing the system ground state energy and the\nsingle-particle wave functions in the correlated state. The many-body wave\nfunction is taken in the Jastrow form and the Variational Monte-Carlo (VMC)\nmethod is used in combination with an ab initio approach to determine the\nenergy. Both the effective Bohr radii of the renormalized single-particle wave\nfunctions and the many-body wave function parameters are determined for each\n$f$. Hence, the evolution of the system can be analyzed in detail as a function\nof the equilibrium intermolecular distance, which in turn is determined for\neach $f$ value. The transition to the atomic state, including the Peierls\ndistortion stability, can thus be studied in a systematic manner, particularly\nnear the threshold of the dissociation of the molecular into atomic chain. The\ncomputational reliability of VMC approach is also estimated.",
        "positive": "Disorder-free sputtering method on graphene: Deposition of various materials onto graphene without causing any disorder is\nhighly desirable for graphene applications. Especially, sputtering is a\nversatile technique to deposit various metals and insulators for spintronics,\nand indium tin oxide to make transparent devices. However, the sputtering\nprocess causes damage to graphene because of high energy sputtered atoms. By\nflipping the substrate and using a high Ar pressure, we demonstrate that the\nlevel of damage to graphene can be reduced or eliminated in dc, rf, and\nreactive sputtering processes."
    },
    {
        "anchor": "Out of equilibrium anomalous elastic response of a water nano-meniscus: We report the observation of a transition in the dynamical properties of\nwater nano-menicus which dramatically change when probed at different time\nscales. Using a AFM mode that we name Force Feedback Microscopy, we observe\nthis change in the simultaneous measurements, at different frequencies, of the\nstiffness G'(N/m), the dissipative coefficient G''(kg/sec) together with the\nstatic force. At low frequency we observe a negative stiffness as expected for\ncapillary forces. As the measuring time approaches the microsecond, the dynamic\nresponse exhibits a transition toward a very large positive stiffness. When\nevaporation and condensation gradually lose efficiency, the contact line\nprogressively becomes immobile. This transition is essentially controlled by\nvariations of Laplace pressure.",
        "positive": "Torsional strain engineering of transition metal dichalcogenide\n  nanotubes: An ab initio study: We study the effect of torsional deformations on the electronic properties of\nsingle-walled transition metal dichalcogenide (TMD) nanotubes. In particular,\nconsidering forty-five select armchair and zigzag TMD nanotubes, we perform\nsymmetry-adapted Kohn-Sham density functional theory calculations to determine\nthe variation in bandgap and effective mass of charge carriers with twist. We\nfind that metallic nanotubes remain so even after deformation, whereas\nsemiconducting nanotubes experience a decrease in bandgap with twist --\noriginally direct bandgaps become indirect -- resulting in semiconductor to\nmetal transitions. In addition, the effective mass of holes and electrons\ncontinuously decrease and increase with twist, respectively, resulting in\nn-type to p-type semiconductor transitions. We find that this behavior is\nlikely due to rehybridization of orbitals in the metal and chalcogen atoms,\nrather than charge transfer between them. Overall, torsional deformations\nrepresent a powerful avenue to engineer the electronic properties of\nsemiconducting TMD nanotubes, with applications to devices like sensors and\nsemiconductor switches."
    },
    {
        "anchor": "Colossal electroresistance effect around room temperature in LuFe2O4: A colossal electroresistance effect is observed around room temperature in a\ntransition metal oxide LuFe2O4. The measurements of resistance under various\napplied voltages as well as the highly nonlinear current-voltage\ncharacteristics reveal that a small electric field is able to drive the\nmaterial from the insulating state to a metallic state. The threshold field at\nwhich the insulating-metallic transition occurs, decreases exponentially with\nincreasing temperature. We interpret this transition as a consequence of the\nbreakdown of the charge-ordered state triggered by applied electric field,\nwhich is supported by the dramatic dielectric response in a small electric\nfield. This colossal electroresistance effect as well as the high dielectric\ntunability around room temperature in low applied fields makes LuFe2O4 a very\npromising material for many applications.",
        "positive": "Perfect spin-fillter and spin-valve in carbon atomic chains: We report ab initio calculations of spin-dependent transport in single atomic\ncarbon chains bridging two zigzag graphene nanoribbon electrodes. Our\ncalculations show that carbon atomic chains coupled to graphene electrodes are\nperfect spin-filters with almost 100 % spin polarization. Moreover, carbon\natomic chains can also show a very large bias-dependent magnetoresistance up to\n1000000 % as perfect spin-valves. These two spin-related properties are\nindependent on the length of carbon chains. Our report, the spin-filter and\nspin-valve are conserved in a single device simultaneously, opens a new way to\nthe application of all-carbon composite spintronics."
    },
    {
        "anchor": "Advanced in silico characterization of nanomaterials for nanoparticle\n  toxicology: Nanomaterials possess a wide range of potential applications due to their\nnovel properties compared to bulk matter, but these same properties may\nrepresent an unknown risk to health. Experimental safety testing cannot keep\npace with the rate at which new nanoparticles are developed and, being lengthy\nand expensive, often hinders the development of technology. An economic\nalternative to in vitro and in vivo testing is offered by nanoinformatics,\npotentially enabling the quantitative relation of the nanomaterial properties\nto their crucial biological activities. Recent research efforts have\ndemonstrated that such activities can be successfully predicted from the\nphysicochemical characteristics of nanoparticles, especially those related to\nthe bionano interface, by means of statistical models. In this work, as a step\ntowards in silico prediction of toxicity of nanomaterials, an advanced\ncomputational characterization of these materials has been proposed and applied\nto titanium dioxide nanoparticles. The characteristics of nanoparticles and\nbionano interface are computed using a systematic multiscale approach relying\nonly on information on chemistry and structure of the nanoparticles.",
        "positive": "A Molecular Dynamics Investigation of Mechanical Properties of Graphene\n  Reinforced Iron Composite and The Effect of Vacancy Defect Distance from the\n  Matrix-Fiber Interface: Graphene is a material of excellent mechanical properties, which make it an\nideal fiber for reinforcing metal. Since iron is the most used metal in the\nworld, reinforcing iron with graphene can reduce the overall requirement of\nmaterial in any application where strength is demanded. However, the effect of\ngraphene reinforcement on the mechanical properties of iron needs to be known\nbefore the industrial application of the composite. In this paper, we have\ninvestigated the mechanical properties of graphene-reinforced iron composite by\nMolecular Dynamics (MD) method for various conditions. The properties were\ninvestigated by applying uniaxial tension on a modeled representative volume\nelement (RVE). The effect of temperature on the mechanical property of the\ncomposite was also studied because the knowledge is required for manufacturing\nproducts with the composite operating at a wide temperature range. MD analysis\nalso revealed that the initiation of fracture is from the matrix-fiber\ninterface. We also investigated how the distance of vacancy defects from the\nmatrix-fiber interface affects the mechanical properties of the composite,\nwhich can be used to select a suitable manufacturing process. The results\nobtained from this study show that vacancy defects lower the strength at a\ngreater extent as it gets closer to the interface."
    },
    {
        "anchor": "Polarization Dependent Optical Control of Atomic Arrangement in\n  Multilayer Ge-Sb-Te Phase Change Materials: We report the optical perturbation of atomic arrangement in the layered\nGeTe/Sb_{2}Te_{3} phase change memory material. To observe the structural\nchange, the coherent A_{1} mode of GeTe_{4} local structure is investigated at\nvarious polarization angles of femtosecond pump pulses with the fluence at < 78\n\\mu J/cm^{2}. p-polarization found to be more effective in inducing the A_{1}\nfrequency shift that can be either reversible or irreversible, depending on the\npump fluence. The predominant origin of this shift is attributed to\nrearrangement of Ge atoms driven by anisotropic dissociation of the Ge-Te bonds\nalong the [111] axis after the p-polarized pulse irradiation.",
        "positive": "Fully coupled electromagnetic-thermal-mechanical comparative simulation\n  of direct vs hybrid microwave sintering of 3Y-ZrO 2: Direct and hybrid microwave sintering of 3Y-ZrO 2 are comparatively studied\nat frequency of 2.45 GHz. Using the continuum theory of sintering, a fully\ncoupled electromagnetic-thermalmechanical (EMTM) finite element simulation is\ncarried out to predict powder samples deformation during their microwave\nprocessing. Direct and hybrid heating configurations are computationally tested\nusing advanced heat transfer simulation tools including the surface to surface\nthermal radiation boundary conditions and a numeric\nproportional-integral-derivative (PID) regulation. The developed modeling\nframework shows a good agreement of the calculation results with the known\nexperimental data on the microwave sintering of 3Y-ZrO 2 in terms of the\ndensification kinetics. It is shown that the direct heating configuration\nrenders highly hot spot effects resulting in non-homogenous densification\ncausing processed specimen's final shape distortions. Compared to the direct\nheating, the hybrid heating configuration provides a reduction of the thermal\ninhomogeneity along with a densification homogenization. As a result of the\nhybrid heating, the total densification of the specimen is attained without\nspecimen distortions. It is also shown that the reduction of the sample size\nhas a stabilization effect on the temperature and relative density spatial\ndistributions."
    },
    {
        "anchor": "Hysteresis features of the transition-metal dichalcogenides VX$_2$ (X=S,\n  Se, and Te): Very recently, it has been shown that vanadium dichalcogenides (VX$_2$, X=S,\nSe and Te) monolayers show intrinsic ferromagnetism, and their critical\ntemperatures are nearly to or beyond room temperature. Hence, they would have\nwide potential applications in next-generation nanoelectronic and spintronic\ndevices. In this work, being inspired by a recent study we systematically\nperform Monte Carlo simulations based on single-site update Metropolis\nalgorithm to investigate the hysteresis features of VX$_2$ monolayers for a\nwide range of temperatures up to 600 K. Our simulation results indicate that,\nboth remanence and coercivity values tend to decrease with increasing\ntemperature. Furthermore, it is found that hysteresis curves start to evolve\nfrom rectangular at the lower temperature regions to nearly S-shaped with\nincreasing temperature.",
        "positive": "Surfactant effects in monodisperse magnetite nanoparticles of controlled\n  size: Monodisperse magnetite Fe3O4 nanoparticles of controlled size within 6 and 20\nnm in diameter were synthesized by thermal decomposition of an iron organic\nprecursor in an organic medium. Particles were coated with oleic acid. For all\nsamples studied, saturation magnetization Ms reaches the expected value for\nbulk magnetite, in contrast to results in small particle systems for which Ms\nis usually much smaller due to surface spin disorder. The coercive field for\nthe 6 nm particles is also similar to that of bulk magnetite. Both results\nsuggest that the oleic acid molecules covalently bonded to the nanoparticle\nsurface yield a strong reduction in the surface spin disorder. However,\nalthough the saturated state may be similar, the approach to saturation is\ndifferent and, in particular, the high-field differential susceptibility is one\norder of magnitude larger than in bulk materials. The relevance of these\nresults in biomedical applications is discussed."
    },
    {
        "anchor": "Space symmetries draw elasticity theory: The foundation of continuum elasticity theory is based on two general\nprinciples: (i) the force felt by a small volume element from its surrounding\nacts only through its surface (the Cauchy principle, justified by the fact that\ninteractions are of short range and are therefore localized at the boundary);\n(ii) the stress tensor must be symmetric in order to prevent spontaneous\nrotation of the material points. These two requirements are presented to be\nnecessary in classical textbooks on elasticity theory. By using only basic\nspatial symmetries it is shown that elastodynamics equations can be derived,\nfor high symmetry crystals (the typical case considered in most textbooks),\nwithout evoking any of the two above physical principles.",
        "positive": "Quantum Size Effect and Electronic Stability of Freestanding Metal Atom\n  Wires: Using DFT calculations, we present a thorough study of the quantum size\neffects on the stability of freestanding metal atom wires. Our systems include\nNa, Ag, Au, In, Ga and Pb atom wires, i.e. $s$, $sd$, and $sp$ electron\nprototypes. We found that the total energy always oscillates with the wire\nlength, which clearly indicates the existence of preferred lengths. Increasing\nthe length, the s-system exhibits even-odd oscillations following a $a/x\n+b/x^2$ decay law in the stability, which can be attributed to electron band\nfilling and quantum confinement along the wire. The $sd$-system exhibits a\nsimilar oscillation pattern, even in the presence of $sd$ hybridization. In\n$sp$-system, the energy oscillations are beyond the simple even-odd nature,\nlikely due to unpaired p orbitals and the corresponding nontrival band filling.\nOur findings clearly demonstrate that electronic contribution is quite critical\nto the stability of freestanding wires, and this stability may be important\neven when wires are deposited on substrates or strained. This study sheds light\non the underlying formation mechanism of metal atom wires."
    },
    {
        "anchor": "Atomistic modelling of all dislocations and twins in HCP and BCC Ti: Ti exhibits complex plastic deformation controlled by active dislocation and\ntwinning systems. Understandings on dislocation cores and twin interfaces are\ncurrently not complete or quantitative, despite extensive experimental and\nsimulation studies. Here, we determine all the core and twin interface\nproperties in both HCP and BCC Ti using a Deep Potential (DP) and DFT. We\ndetermine the core structures, critical resolved shear stresses and mobilities\nof <a>, <c+a>, <c> dislocations in HCP and <111>/2 dislocations in BCC Ti. The\n<a> slip consists of slow core migration on pyramidal-I planes and fast\nmigration on prism-planes, and is kinetically limited by cross-slips among\nthem. This behaviour is consistent with \"locking-unlocking\" phenomena in TEM\nand is likely an intrinsic property. Large-scale DFT calculations provide a\npeek at the screw <c+a> core and glide behaviour, which is further quantified\nusing DP-Ti. The screw <c+a> is unstable on pyramidal-II planes. The mixed\n<c+a> is nearly sessile on pyramidal-I planes, consistent with observations of\nlong dislocations in this orientation. The edge and mixed <c+a> are unstable\nagainst a pyramidal-to-basal (PB) transition and become sessile at high\ntemperatures, corroborate the difficulties in <c>-axis compression of Ti.\nFinally, in BCC Ti, the <111>/2 screw has a degenerate core with average glide\non {112} planes; the <111>/2 edge and mixed dislocations have non-dissociated\ncores on {110} planes. This work paints a self-consistent, complete picture on\nall dislocations in Ti, rationalises previous experimental observations and\npoints to future HRTEM examinations of unusual dislocations such as the mixed\nand PB transformed <c+a> cores.",
        "positive": "Thermoelectric Effects in Anisotropic Systems: Measurement and\n  Applications: The Harman method for measuring the thermal conductivity of a sample using\nthe Peltier effect, may also be used to determine the dimensionless figure of\nmerit from just two electrical resistance measurements. We consider a modified\nversion of the Harman method where the current contacts are much smaller than\nthe contact faces of the sample. We calculate the voltage and temperature\ndistributions in a rectangular sample of a material having anisotropy in all of\nits transport coefficients. The thermoelectric anisotropy has important\nconsequences in the form of thermoelectric eddy currents and the Bridgman\neffect. We prove that in the limit of a very thin sample of arbitrary shape,\nthere exist van der Pauw formulae relating particular linear combinations of\nthe potential and temperature differences between points on the edges of the\nsample. We show that the Harman figure of merit can be radically different from\nthe intrinsic figures of merit of the material, and can often be substantially\nenhanced. By defining an effective figure of merit in terms of the rate of\nentropy production, we show that the increase in the Harman figure of merit\ndoes indicate an improvement in the thermoelectric performance of an\nanisotropic sample having small current contacts. However, we also prove that\nin the case of a material with tetragonal symmetry, the effective figure of\nmerit is always bounded from above by the largest intrinsic figure of merit of\nthe material."
    },
    {
        "anchor": "On the origin of magnetism in (Ga,Mn)As: from paramagnetic through\n  superparamagnetic to ferromagnetic phase: The high-spectral-resolution spectroscopic studies of the energy gap\nevolution, supplemented with electronic, magnetic and structural\ncharacterization, show that the modification of the GaAs valence band caused by\nMn incorporation occurs already for a very low Mn content, much lower than that\nrequired to support ferromagnetic spin - spin coupling in (Ga,Mn)As. Only for\nn-type (Ga,Mn)As with the Mn content below about 0.3% the Mn-related extended\nstates are visible as a feature detached from the valence-band edge and partly\noccupied with electrons. The combined magnetic and low-temperature\nphotoreflectance studies presented here indicate that the paramagnetic -\nferromagnetic transformation in p-type (Ga,Mn)As takes place without imposing\nchanges of the unitary character of the valence band with the Fermi level\nlocated therein. The whole process is rooted in the nanoscale fluctuations of\nthe local (hole) density of states and the formation of a\nsuperparamagnetic-like state. The Fermi level in (Ga,Mn)As is coarsened by the\ncarrier concentration of the itinerant valence band holes and further\nfine-tuned by the many-body interactions.",
        "positive": "Two successive magneto-structural transformations and their relation to\n  enhanced magnetocaloric effect for Ni55.3Mn19.7Ga25 Heusler alloy: In the present work, two successive magneto-structural transformations (MSTs)\nconsisting of martensitic and intermartensitic transitions have been reported\nin polycrystalline Ni55.8Mn18.1Ga26.1 Heusler alloy. Benefiting from the\nadditional latent heat contributed from intermediate phase, this alloy exhibits\na large transition entropy change {\\Delta}Str with the value of ~28 J/kg K.\nMoreover, the magnetocaloric effect (MCE) has been also evaluated in terms of\nMaxwell relation. For the magnetic field change of 3 T, it is found that the\ncalculated value of refrigeration capacity for Ni55.8Mn18.1Ga26.1 attains to\n~72 J/kg around room temperature, which significantly surpasses those obtained\nin many Ni-Mn based Heusler alloys. The mechanism underlying the enhanced MCE\nis believed to be responsible for these multiple transformations, which can\nsustain the pronounced isothermal entropy change {\\Delta}ST over a relatively\nwide temperature interval."
    },
    {
        "anchor": "Refractive index of vanadium determined by resonant diffraction of soft\n  x-rays: The dispersive part of the refractive index of vanadium is determined by\nmeasuring the angular displacement of the first order diffraction peak of a\nV/Fe superlattice. The measurements were made using elliptically polarized\nsynchrotron radiation which was scanned through the V L2,3 absorption edges for\ndifferent incident scattering angles. The x-ray scattering technique provides\naccess to direct determination of the dispersive part of the refractive index\nthrough an absorption resonance. The influence of absorption at the resonances\nis shown by comparing the absorption correction to the dispersion correction.\nThe results demonstrate that 1-{\\delta} is larger than unity at the L2,3\nresonances of vanadium and the optical consequences are discussed.",
        "positive": "Strong interrelationship between anomalous electric-field induced\n  lattice strain along non-polar direction and domain reorientation in\n  pseudorhombohedral piezoelectric ceramic BiScO3-PbTiO3: The lattice strain and domain switching behaviour was investigated as a\nfunction of cyclic field and grain orientation for a pseudorhombohedral\ncomposition of the high Curie point piezoelectric system xBiScO3 - (1-x)PbTiO3\n(x = 0.40) by in-situ electric field diffraction technique with high energy\nsynchrotron x-rays. Along the field direction, the system exhibts five time\nlarge strain along 100 as compared to the 111 direction. A one-to-one\ncorrespondence between the 200 lattice strain and the 111 domain switching\nsuggests a strong correlation between the two phenomena."
    },
    {
        "anchor": "Nonempirical Range-separated Hybrid Functionals for Solids and Molecules: Dielectric-dependent hybrid (DDH) functionals were recently shown to yield\naccurate energy gaps and dielectric constants for a wide variety of solids, at\na computational cost considerably less than that of GW calculations. The\nfraction of exact exchange included in the definition of DDH functionals\ndepends (self-consistently) on the dielectric constant of the material. Here we\nintroduce a range-separated (RS) version of DDH functionals where short and\nlong-range components are matched using system dependent, non-empirical\nparameters. We show that RS DDHs yield accurate electronic properties of\ninorganic and organic solids, including energy gaps and absolute ionization\npotentials. Furthermore we show that these functionals may be generalized to\nfinite systems.",
        "positive": "Perturbation of charge density waves in 1T-TiSe$_2$: In this study, using low-temperature scanning tunneling microscopy (STM), we\nfocus on understanding the native defects in pristine \\textit{1T}-TiSe$_2$ at\nthe atomic scale. We probe how they perturb the charge density waves (CDWs) and\nlead to local domain formation. These defects influence the correlation length\nof CDWs. We establish a connection between suppression of CDWs, Ti\nintercalation, and show how this supports the exciton condensation model of CDW\nformation in \\textit{1T}-TiSe$_2$."
    },
    {
        "anchor": "Theoretical investigation of polarization-compensated II-IV/I-V\n  perovskite superlattices: Recent work suggested that head-to-head and tail-to-tail domain walls could\nbe induced to form in ferroelectric superlattices by introducing compensating\n\"delta doping\" layers via chemical substitution in specified atomic planes\n[Phys. Rev. B 73, 020103(R), 2006]. Here we investigate a variation of this\napproach in which superlattices are formed of alternately stacked groups of\nII-IV and I-V perovskite layers, and the \"polar discontinuity\" at the II-IV/I-V\ninterface effectively provides the delta-doping layer. Using first-principles\ncalculations on SrTiO3/KNbO3 as a model system, we show that this strategy\nallows for the growth of a superlattice with stable polarized regions and large\npolarization discontinuities at the internal interfaces. We also generalize a\nWannier-based definition of layer polarizations in perovskite superlattices\n[Phys. Rev. Lett. 97, 107602 (2006)] to the case in which some (e.g., KO or\nNbO2) layers are non-neutral, and apply this method to quantify the local\nvariations in polarization in the proposed SrTiO3/KNbO3 superlattice system.",
        "positive": "Edge Stability of BN sheets and Its Application for Designing Hybrid BNC\n  Structures: First-principles investigations on the edge energies and edge stresses of\nsingle-layer hexagonal boron-nitride (BN) are presented. The armchair edges of\nBN nanoribbons (BNNRs) are more stable in energy than zigzag ones. Armchair\nBNNRs are under compressive edge stress while zigzag BNNRs are under tensile\nedge stress. The intrinsic spin-polarization and edge saturation play important\nroles in modulating the edge stability of BNNRs. The edge energy difference\nbetween BN and graphene could be used to guide the design of the specific\nhybrid BNC structures: in an armchair BNC nanoribbon (BNCNR), BN domains are\nexpected to grow outside of C domains, while the opposite occurs in a zigzag\nBNCNR. More importantly, armchair BNCNRs can reproduce unique electronic\nproperties of armchair graphene nanoribbons (GNRs), which are expected to be\nrobust against edge functionalization or disorder. Within certain C/BN ratio,\nzigzag BNCNRs may exhibit intrinsic half-metallicity without any external\nconstraints. These unexpected electronic properties of BNCNRs may offer unique\nopportunities to develop nanoscale electronics and spintronics beyond\nindividual graphene and BN. Generally, these principles for designing BNC could\nbe extended to other hybrid nanostructures."
    },
    {
        "anchor": "The radiative characteristics of quantum-well active region of AlGaAs\n  lasers with separate-confinement heterostructure (SCH): Computer simulations with Synopsys' Sentaurus TCAD are used to study the\neffect of the molar concentration of aluminum in the active and waveguide\nregions on the energy spectrum of carriers in Quantum Well (QW) and the optical\nspectral characteristics of radiation of semiconductor lasers with AlxGa1-xAs\ndouble heterostructures and separate confinement (SCH). Wavelength of\nsingle-mode lasers is shown to be almost independent of the concentration of\naluminum in the waveguide, in a wide range of aluminum content, but to depend\nmainly on Al concentrations in QW region.",
        "positive": "Anharmonicity-induced isostructural phase transition of Zirconium under\n  pressure: We have performed a detailed x-ray diffraction structural study of Zr under\npressure and unambiguously identify the existence of a first-order\nisostructural bcc-to-bcc phase transition near 58 GPa. First-principles quantum\nmolecular dynamics lattice dynamics calculations support the existence of this\nphase transition, in excellent agreement with experimental results, triggered\nby anharmonic effects. Our results highlight the potential ubiquity of\nanharmonically driven isostructural transitions within the periodic table under\npressure and calls for follow-up experimental and theoretical studies."
    },
    {
        "anchor": "Quantum spin configurations in Tb2Ti2O7: Low energy collective angular momentum states of the Tb3+ ions in Tb2Ti2O7\nare classified according to the irreducible representations of the octahedral\npoint group. Degeneracy lifting due to the exchange interaction is discussed.\nDiffuse neutron scattering intensity patterns are calculated for each\ncollective angular momentum state and the ground state is inferred by comparing\nto experiment.",
        "positive": "Thermoelectric Transport Coefficients in Mono-layer MoS2 and WSe2 Role\n  of Substrate, Interface Phonons, Plasmon, and Dynamic Screening: The thermoelectric transport coefficients of electrons in two recently\nemerged transition metal dichalcogenides(TMD), MoS2 and WSe2, are calculated by\nsolving Boltzmann Transport equation and coupled electrical and thermal current\nequations using Rode iterative technique. Scattering from localized donor\nimpurities, acoustic deformation potential, longitudinal optical (LO) phonons,\nand substrate induced remote phonon modes are taken into account. Hybridization\nof TMD plasmon with remote phonon modes is investigated. Dynamic screening\nunder linear polarization response is explored in TMDs sitting on a dielectric\nenvironment and the screened electron-phonon coupling matrix elements are\ncalculated. The effect of screening and substrate induced remote phonon\nmediated scattering on the transport coefficients of the mentioned materials is\nexplained. The transport coefficients are obtained for a varying range of\ntemperature and doping density for three different types of substrates SiO2,\nAl2O3, and HfO2. The thermoelectric properties of interest including Seebeck\ncoefficient, Peltier coefficient, and electronic thermal conductivity are\ncalculated."
    },
    {
        "anchor": "Electron reflectivity measurements of Ag adatom concentrations on W(110): The density of two-dimensional Ag adatom gases on W(110) is determined by\nmonitoring local electron reflectivity using low energy electron microscopy\n(LEEM). This method of adatom concentration measurement can detect changes in\nadatom density at least as small as 10$^{-3}$ ML for a $\\mu$m size region of\nthe surface. Using this technique at high temperatures, we measure the\nsublimation rates of Ag adatoms on W(110). At lower temperatures, where Ag\nadatoms condense into monolayer islands, we determine the temperature\ndependence of the density of adatoms coexisting with this condensed phase and\ncompare it with previous estimates.",
        "positive": "Atomistic calculation of the f0 attempt frequency in Fe3O4 magnetite\n  nanoparticles: The Arrhenius law predicts the transition time between equilibrium states in\nphysical systems due to thermal activation, with broad applications in material\nscience, magnetic hyperthermia and paleomagnetism where it is used to estimate\nthe transition time and thermal stability of assemblies of magnetic\nnanoparticles. Magnetite is a material of great importance in paleomagnetic\nstudies and magnetic hyperthermia but existing estimates of the attempt\nfrequency $f_0$ vary by several orders of magnitude in the range $10^7-10^{13}$\nHz, leading to significant uncertainty in their relaxation rate. Here we\npresent a dynamical method enabling full parameterization of the\nArrhenius-N\\'eel law using atomistic spin dynamics. We determine the\ntemperature and volume dependence of the attempt frequency of magnetite\nnanoparticles with cubic anisotropy and find a value of $f_0 = 0.562 \\pm 0.059$\nGHz at room temperature. For particles with enhanced anisotropy we find a\nsignificant increase in the attempt frequency and a strong temperature\ndependence suggesting an important role of anisotropy. The method is applicable\nto a wide range of dynamical systems where different states can be clearly\nidentified and enables robust estimates of domain state stabilities, with\nparticular importance in the rapidly developing field of micromagnetic analysis\nof paleomagnetic recordings where samples can be numerically reconstructed to\nprovide a better understanding of geomagnetic recording fidelity over\ngeological time scales."
    },
    {
        "anchor": "Experimental measurements of the temperature-dependent Van Hove function\n  in a $\\text{Zr}_{80} \\text{Pt}_{20}$ liquid: Even though the viscosity is one of the most fundamental properties of\nliquids, the connection with the atomic structure of the liquid has proven\nelusive. By combining inelastic neutron scattering with the electrostatic\nlevitation technique the time-dependent pair-distribution function (i.e. the\nVan Hove function) has been determined for liquid Zr80Pt20. We show that the\ndecay-time of the first peak of the Van Hove function is directly related to\nthe Maxwell relaxation time of the liquid, which is proportional to the shear\nviscosity. This result demonstrates that the local dynamics for increasing or\ndecreasing the coordination number of local clusters by one determines the\nviscosity at high temperature, supporting earlier predictions from molecular\ndynamics simulations.",
        "positive": "Freeing electrons from extrinsic and intrinsic disorder yields band-like\n  transport in n-type organic semiconductors: Charge transport in organic semiconductors is notoriously extremely sensitive\nto the presence of disorder, both intrinsic and extrinsic, especially for\nn-type materials. Intrinsic dynamic disorder stems from large thermal\nfluctuations both in intermolecular transfer integrals and (molecular) site\nenergies in weakly interacting van der Waals solids and sources transient\nlocalization of the charge carriers. The molecular vibrations that drive\ntransient localization typically operate at low-frequency (< a-few-hundred\ncm-1), which renders it difficult to assess them experimentally. Hitherto, this\nhas prevented the identification of clear molecular design rules to control and\nreduce dynamic disorder. In addition, the disorder can also be extrinsic, being\ncontrolled by the gate insulator dielectric properties. Here we report on a\ncomprehensive study of charge transport in two closely related n-type molecular\norganic semiconductors using a combination of temperature-dependent inelastic\nneutron scattering and photoelectron spectroscopy corroborated by electrical\nmeasurements, theory and simulations. We provide unambiguous evidence that ad\nhoc molecular design enables to free the electron charge carriers from both\nintrinsic and extrinsic disorder to ultimately reach band-like electron\ntransport."
    },
    {
        "anchor": "Thermoelectric properties of $\u03b2$-FeSi$_{\\text2}$: We investigate the thermoelectric properties of ${\\beta}$-FeSi$_{\\text2}$\nusing first principles electronic structure and Boltzmann transport\ncalculations. We report a high thermopower for both \\textit{p}- and\n\\textit{n}-type ${\\beta}$-FeSi$_{\\text2}$ over a wide range of carrier\nconcentration and in addition find the performance for \\textit{n}-type to be\nhigher than for the \\textit{p}-type. Our results indicate that, depending upon\ntemperature, a doping level of 3$\\times10{^{20}}$ - 2$\\times10{^{21}}$\ncm${^{-3}}$ may optimize the thermoelectric performance.",
        "positive": "Universality of moir\u00e9 physics in collapsed chiral carbon nanotubes: We report the existence of moir\\'e patterns and magic angle physics in all\nfamilies of chiral collapsed carbon nanotubes. A detailed study of the\nelectronic structure of all types of chiral nanotubes, previously collapsed via\nmolecular dynamics, has been performed. We find that each family possesses a\nunique geometry and moir\\'e disposition, as well as a characteristic number of\nflat bands. Remarkably, all kinds of nanotubes behave the same with respect to\nmagic angle tuning, showing a monotonic behavior that gives rise to magic\nangles in full agreement with those of twisted bilayer graphene. Therefore,\nmagic angle behavior is universally found in chiral collapsed nanotubes with a\nsmall chiral angle, giving rise to moir\\'e patterns. Our approach comprises\nfirst-principles and semi-empirical calculations of the band structure, density\nof states and spatial distribution of the localized states signaled by flat\nbands."
    },
    {
        "anchor": "Structural, dielectric and electrocaloric properties of\n  (Ba0.85Ca0.15)(Ti0.9Zr0.1-xSnx)O3 ceramics elaborated by sol-gel method: Ferroelectric ceramics (Ba0.85Ca0.15)(Ti0.9Zr0.1-xSnx)O3 (x=0.00, 0.02, 0.04,\n0.06) were prepared by a sol-gel method. Structural investigation revealed the\nco-existence of tetragonal (P4mm) and orthorhombic (Pmm2) symmetries at room\ntemperature for the undoped ceramic, while only a tetragonal structure (P4mm)\nwas observed for the doped ceramics. Dielectric measurements indicate a\ndielectric relaxation process at high temperatures which is essentially related\nto the hopping of oxygen vacancies. Furthermore, a down shifting of the Curie\ntemperature (TC) with increasing Sn4+ doping rate has been revealed. The\ntemperature profiles of the Raman spectra unveiled the existence of polar\nnanoregions (PNRs) above the Curie temperature in all ceramics. The\nferroelectric properties were found to be related to the microstructure.\nElectrocaloric effect was investigated in this system that revealed an\nelectrocaloric responsivity of 0.225 10-6 K m/V for the composition with x =\n0.04 Sn doping, where other remarkable physical properties were also observed.",
        "positive": "Exploring the possibility of enhancing the figure-of-merit ( $>$ 2) of\n  Na$_{0.74}$CoO$_{2}$: A combined experimental and theoretical study: Search of new thermoelectric (TE) materials with high\n\\textit{figure-of-merit} (ZT) is always inspired the researcher in TE field.\nHere, we present a combined experimental and theoretical study of TE properties\nof Na$_{0.74}$CoO$_{2}$ compound in high-temperature region. The experimental\nSeebeck coefficient (S) is found to vary from 64 to 118 $\\mu$V/K in the\ntemperature range $300-620$ K. The positive values of S are indicating the\ndominating p-type behaviour of the compound. The observed value of thermal\nconductivity ($\\kappa$) is $\\sim$ 2.2 W/m-K at 300 K. In the temperature region\n$300-430$ K, the value of $\\kappa$ increases up to $\\sim$ 2.6 W/m-K and then\ndecreases slowly till 620 K with the corresponding value of $\\sim$ 2.4 W/m-K.\nWe have also carried out the theoretical calculations and the best matching\nbetween experimental and calculated values of transport properties are observed\nin spin-polarized calculation within DFT+\\textit{U} by chosen \\textit{U} = 4\neV. The maximum calculated value of ZT is found to be $\\sim$ 0.67 at 1200 K for\np-type conduction. Our computational study suggests that the possibility of\nn-type behaviour of the compound which can lead to a large value of ZT at\nhigher temperature region. Electron doping of $\\sim$ 5.1$\\times$10$^{20}$\ncm$^{-3}$ is expected to give rise the high ZT value of $\\sim$ 2.7 at 1200 K.\nUsing these temperature-dependent ZT values, we have calculated the maximum\npossible values of efficiency ($\\eta$) of thermoelectric generator (TEG) made\nby p and n-type Na$_{0.74}$CoO$_{2}$. The present study suggests that one can\nget the efficiency of a TE cell as high as $\\sim$ 11$\\%$ when the cold and hot\nend temperature are fixed at 300 K and 1200 K, respectively. Such high values\nof ZT and efficiency suggest that Na$_{0.74}$CoO$_{2}$ can be used as a\npotential candidate for high-temperature TE applications."
    },
    {
        "anchor": "Microscopic Theory for Coupled Atomistic Magnetization and Lattice\n  Dynamics: A coupled atomistic spin and lattice dynamics approach is developed which\nmerges the dynamics of these two degrees of freedom into a single set of\ncoupled equations of motion. The underlying microscopic model comprises local\nexchange interactions between the electron spin and magnetic moment and the\nlocal couplings between the electronic charge and lattice displacements. An\neffective action for the spin and lattice variables is constructed in which the\ninteractions among the spin and lattice components are determined by the\nunderlying electronic structure. In this way, expressions are obtained for the\nelectronically mediated couplings between the spin and lattice degrees of\nfreedom, besides the well known inter-atomic force constants and spin-spin\ninteractions. These former susceptibilities provide an atomistic ab initio\ndescription for the coupled spin and lattice dynamics. It is important to\nnotice that this theory is strictly bilinear in the spin and lattice variables\nand provides a minimal model for the coupled dynamics of these subsystems and\nthat the two subsystems are treated on the same footing. Questions concerning\ntime-reversal and inversion symmetry are rigorously addressed and it is shown\nhow these aspects are absorbed in the tensor structure of the interaction\nfields. By means of these results regarding the spin-lattice coupling, simple\nexplanations of ionic dimerization in double anti-ferromagnetic materials, as\nwell as, charge density waves induced by a non-uniform spin structure are\ngiven. In the final parts, a set of coupled equations of motion for the\ncombined spin and lattice dynamics are constructed, which subsequently can be\nreduced to a form which is analogous to the Landau-Lifshitz-Gilbert equations\nfor spin dynamics and damped driven mechanical oscillator for the ...",
        "positive": "Band structure and carrier effective masses of boron arsenide: effects\n  of quasiparticle and spin-orbit coupling corrections: We determine the fundamental electronic and optical properties of the\nhigh-thermal-conductivity III-V semiconductor boron arsenide (BAs) using\ndensity functional and many body perturbation theory including quasiparticle\nand spin-orbit coupling corrections. We find that the fundamental band gap is\nindirect with a value of 2.049 eV, while the minimum direct gap has a value of\n4.135 eV. We calculate the carrier effective masses and report smaller values\nfor the holes than the electrons, indicating higher hole mobility and easier\np-type doping. The small difference between the static and high frequency\ndielectric constants indicates that BAs is only weakly ionic. We also observe\nthat the imaginary part of the dielectric function exhibits a strong absorption\npeak, which corresponds to parallel bands in the band structure. Our estimated\nexciton binding energy of 43 meV indicates that excitons are relatively stable\nagainst thermal dissociation at room temperature. Our work provides theoretical\ninsights on the fundamental electronic properties of BAs to guide experimental\ncharacterization and device applications."
    },
    {
        "anchor": "Vibrational and thermoelastic properties of bcc iron from selected EAM\n  potentials: A comprehensive, critical study of the vibrational, thermodynamic and\nthermoelastic properties of bcc iron is presented, using well established\nsemi-empirical embedded-atom method potentials available in the literature.\nClassical molecular dynamics simulations are used to address temperature\neffects, where dynamical matrices are constructed as a time average of the\nsecond moment of the atomic displacements. The $C_{11}, C_{44}, C'$ elastic\nconstants are then obtained from the sound velocities along high symmetry\ndirections in reciprocal space. Results are compared to ultrasonic measurements\nand highlight the limitations of the potentials considered here in describing\nthermoelastic properties.",
        "positive": "Electromagnetic properties of polycrystalline diamond from 35K to room\n  temperature and microwave to terahertz frequencies: Dielectric resonators are key components for many microwave and millimetre\nwave applications, including high-Q filters and frequency-determining elements\nfor precision frequency synthesis. These often depend on the quality of the\ndielectric material. The commonly used material for building the best cryogenic\nmicrowave oscillators is sapphire. However sapphire is becoming a limiting\nfactor for higher frequencies design. It is then important to find new\ncandidates that can fulfil the requirements for millimetre wave low noise\noscillators at room and cryogenic temperatures. These clocks are used as a\nreference in many fields, like modern telecommunication systems, radio\nastronomy (VLBI), and precision measurements at the quantum limit.\nHigh-resolution measurements were made of the temperature-dependence of the\nelectromagnetic properties of a polycrystalline diamond disk at temperatures\nbetween 35 K and 330 K at microwave to sub-millimetre wave frequencies. The\ncryogenic measurements were made using a TE01{\\delta} dielectric mode resonator\nplaced inside a vacuum chamber connected to a single-stage pulse-tube\ncryocooler. The high frequency characterization was performed at room\ntemperature using a combination of a quasi-optical two-lens transmission setup,\na Fabry-Perot cavity and a whispering gallery mode resonator excited with\nwaveguides. Our CVD diamond sample exhibits a decreasing loss tangent with\nincreasing frequencies. We compare the results with well known crystals. This\ncomparison makes clear that polycrystalline diamond could be an important\nmaterial to generate stable frequencies at millimetre waves."
    },
    {
        "anchor": "Flux growth utilizing the reaction between flux and crucible: Flux growth involves dissolving the components of the target compound in an\nappropriate flux at high temperatures and then crystallizing under\nsupersaturation controlled by cooling or evaporating the flux. A refractory\ncrucible is generally used to contain the high temperature melt. The reaction\nbetween the melt and crucible materials can modify the composition of the melt,\nwhich typically results in growth failure, or contaminates the crystals. Thus\none principle in designing a flux growth is to select suitable flux and\ncrucible materials thus to avoid any reaction between them. In this paper, we\nreview two cases of flux growth in which the reaction between flux and\nAl$_2$O$_3$ crucible tunes the oxygen content in the melt and helps the\ncrystallization of desired compositions. For the case of La$_5$Pb$_3$O,\nAl$_2$O$_3$ crucible oxidizes La to form a passivating La$_2$O$_3$ layer which\nnot only prevents further oxidization of La in the melt but also provides [O]\nto the melt. For the case of La$_{0.4}$Na$_{0.6}$Fe$_2$As$_2$, it is believed\nthat the Al$_2$O$_3$ crucible reacts with NaAsO$_2$ and the reaction consumes\noxygen in the melt thus maintaining an oxygen-free environment.",
        "positive": "On the Balance of Intercalation and Conversion Reactions in Battery\n  Cathodes: We present a thermodynamic analysis of the driving forces for intercalation\nand conversion reactions in battery cathodes across a range of possible working\nion, transition metal, and anion chemistries. Using this body of results, we\nanalyze the importance of polymorph selection as well as chemical composition\non the ability of a host cathode to support intercalation reactions. We find\nthat the accessibility of high energy charged polymorphs in oxides generally\nleads to larger intercalation voltages favoring intercalation reactions,\nwhereas sulfides and selenides tend to favor conversion reactions. Furthermore,\nwe observe that Cr-containing cathodes favor intercalation more strongly than\nthose with other transition metals. Finally, we conclude that two-electron\nreduction of transition metals (as is possible with the intercalation of a $2+$\nion) will favor conversion reactions in the compositions we studied."
    },
    {
        "anchor": "Engineering the ligand states by surface functionalization: A new way to\n  enhance the ferromagnetism of CrI3: The newly discovered 2D magnetic materials provide new opportunities for\nbasic physics and device applications. However, their low Curie temperature\n(TC) is a common weakness. In this paper, by combining magnetic Hamiltonian,\nWannier functions and first-principle calculations, we systematically study the\nmagnetic properties of monolayer CrI3 functionalized by halogen. The magnetic\nexchange coupling (EX) and magnetic anisotropy (MA) are found to increase\nsignificantly by X (X=F, Cl and Br) atom adsorption, and increase along with\nthe coverage of X atom. In the frame work of superexchange theory, the enhanced\nEX can be ascribed to the reduced energy difference and increased hopping\nstrength between Cr d and I p orbitals, due to the states of I ligand are\nengineered by X adatom. Besides, the X adatom may provide additional\nferromagnetic superexchange channel. Finally, the CrI3 that one side is fully\nadsorbed by F atoms is found to be a room temperature ferromagnetic\nsemiconductor with TC=650 K. Our results not only give an insightful\nunderstanding for the enhancement of ferromagnetism of CrI3 by atom adsorption,\nbut also propose a promising way to improve the ferromagnetism of 2D magnetic\nmaterials.",
        "positive": "Infrared Spectroscopic Study of Vibrational Modes across the\n  Orthorhombic-Tetragonal Phase Transition in Methylammonium Lead Halide Single\n  Crystals: Single crystals of the methylammonium (MA) lead halides MAPbI3, MAPbBr3, and\nMAPbCl3 have been investigated using infrared spectroscopy with the aim of\nanalyzing structural and dynamical aspects of processes that enable the\nordering of the MA molecule in the orthorhombic crystal structure of these\nhybrid perovskites. Our temperature-dependent studies were focused on the\nanalysis of the CH/NH rocking, C-N stretching, and CH/NH bending modes of the\nMA molecule in the 800-1750 cm-1 frequency range. They deliver a direct\ncomparison of the behavior of the three halides on crossing the\northorhombic-tetragonal phase transition in MA lead halide single crystals.\nDrastic changes of all vibrational modes close to the phase transition were\nclearly observed. Additional spectral features that were not discussed\npreviously are pointed out. The transformation of the 2-dimensional\northorhombic hydrogen bond layers into a more 3-dimensional arrangement in the\ntetragonal phase seems to be an important feature providing deeper insight into\nthe mechanisms that lead to a free-rotating MA molecule in the inorganic host\nstructure. The change of the molecules site symmetry in the tetragonal crystal\nstructure seems to be an important feature of the orthorhombic-tetragonal phase\ntransition. For low temperatures it can be stated that the iodide is stronger\ninfluenced by hydrogen bonding than the bromide and the chloride."
    },
    {
        "anchor": "Kondo effect in single atom contacts: the importance of the atomic\n  geometry: Co single atom junctions on copper surfaces are studied by scanning tunneling\nmicroscopy and ab-initio calculations. The Kondo temperature of single cobalt\natoms on the Cu(111) surface has been measured at various tip-sample distances\nranging from tunneling to the point contact regime. The experiments show a\nconstant Kondo temperature for a whole range of tip-substrate distances\nconsistently with the predicted energy position of the spin-polarized d-levels\nof Co. This is in striking difference to experiments on Co/Cu(100) junctions,\nwhere a substantial increase of the Kondo temperature has been found. Our\ncalculations reveal that the different behavior of the Co adatoms on the two Cu\nsurfaces originates from the interplay between the structural relaxations and\nthe electronic properties in the near-contact regime.",
        "positive": "Orbital contributions in the element-resolved valence electronic\n  structure of Bi2Se3: In this work, we studied the bulk band structure of a topological insulator\n(TI) Bi2Se3 and determined the contributions of the Bi and Se orbital states to\nthe valence bands using standing wave-excited hard x-ray photoemission\nspectroscopy (SW-HAXPES). This SW technique can provide the element-resolved\ninformation and extract individual Bi and Se contributions to the Bi2Se3\nvalence band. Comparisons with density functional theory (DFT) calculations\n(LDA and GW) reveal that the Bi 6s, Bi 6p, and Se 4p states are dominant in the\nBi2Se3 HAXPES valence band. These findings pave a way for studying the\nelement-resolved band structure and orbital contributions of this class of TIs."
    },
    {
        "anchor": "Effect of heteroepitaxial growth on LT-GaAs: ultrafast optical\n  properties: Epitaxial low temperature grown GaAs (LT-GaAs) on silicon (LT-GaAs/Si) has\nthe potential for terahertz (THz) photoconductive antenna applications.\nHowever, crystalline, optical and electrical properties of heteroepitaxial\ngrown LT-GaAs/Si can be very different from those grown on semi-insulating GaAs\nsubstrates (reference). In this study, we investigate optical properties of an\nepitaxial grown LT-GaAs/Si sample, compared to a reference grown under the same\nsubstrate temperature, and with the same layer thickness. Anti-phase domains\nand some crystal misorientation are present in the LT-GaAs/Si. From coherent\nphonon spectroscopy, the intrinsic carrier densities are estimated to be\n~$10^{15}$ cm$^{-3}$ for either sample. Strong plasmon damping is also\nobserved. Carrier dynamics, measured by time-resolved THz spectroscopy at high\nexcitation fluence, reveals markedly different responses between samples. Below\nsaturation, both samples exhibit the desired fast response. Under optical\nfluences $\\geq$ 54 $\\mu$ J/cm$^2$, the reference LT-GaAs layer shows saturation\nof electron trapping states leading to non-exponential behavior, but the\nLT-GaAs/Si maintains a double exponential decay. The difference is attributed\nto the formation of As-As and Ga-Ga bonds during the heteroepitaxial growth of\nLT-GaAs/Si, effectively leading to a much lower density of As-related electron\ntraps.",
        "positive": "Dislocation-assisted linear complexion formation driven by segregation: Atomistic simulations are used to study linear complexion formation at\ndislocations in a body-centered cubic Fe-Ni alloy. Driven by Ni segregation,\nprecipitation of the metastable B2-FeNi and stable L10-FeNi phases occurs along\nthe compression side of edge dislocations. If the Ni segregation is not intense\nenough to ensure precipitate growth and coalescence along the dislocation\nlines, linear complexions in the form of stable nanoscale precipitate arrays\nare observed. Critical conditions such as global composition and temperature\nare defined for both linear complexion formation and dislocation-assisted\nprecipitation."
    },
    {
        "anchor": "Bipolar conduction and giant positive magnetoresistance in doped\n  metallic titanium oxide heterostructures: Empowering conventional materials with unexpected magnetoelectric properties\nis appealing to the multi-functionalization of existing devices and the\nexploration of future electronics. Recently, owing to its unique effect in\nmodulating a matter's properties, ultra-small dopants, e.g. H, D, and Li,\nattract enormous attention in creating emergent functionalities, such as\nsuperconductivity, and metal-insulator transition. Here, we report an\nobservation of bipolar conduction accompanied by a giant positive\nmagnetoresistance in D-doped metallic Ti oxide (TiOxDy) films. To overcome the\nchallenges in intercalating the D into a crystalline oxide, a series of TiOxDy\nwere formed by sequentially doping Ti with D and surface/interface oxidation.\nIntriguingly, while the electron mobility of the TiOxDy increases by an order\nof magnitude larger after doping, the emergent holes also exhibit high\nmobility. Moreover, the bipolar conduction induces a giant magnetoresistance up\nto 900% at 6 T, which is ~6 times higher than its conventional phase. Our study\npaves a way to empower conventional materials in existing electronics and\ninduce novel electronic phases.",
        "positive": "Signature of persistent metallic domains in FORC measurements of the\n  VO$_2$ metal-insulator transition: We have performed first order reversal curve measurements of the\ntemperature-driven metal-insulator transition in VO$_2$ thin films, which\nenable quantitative analysis of the hysteresis behavior. An unexpected\ntail-like feature in the contour plot of the reversal curve distribution\nindicates the existence of metallic domains, even at temperatures below the\nclosing of the hysteresis. These domains interact with the surrounding medium\nand change the reversal path relative to a path from a \\emph{fully} insulating\nstate. With this in mind, and assuming that such interaction persist through\nthe entire phase transition, we develop a model where the driving force (or\nenergy barrier) in charge of opening a hysteresis in VO$_2$ are inter-domain\ninteractions. This model is intrinsically different from the Preisach model\nusually used to describe hysteresis; given that it looks for the microscopic\norigin of the hysteresis, and provides physical parameters to characterize it."
    },
    {
        "anchor": "Three reversible states controlled on a gold monoatomic contact by the\n  electrochemical potential: Conductance of an Au mono atomic contact was investigated under the\nelectrochemical potential control. The Au contact showed three different\nbehaviors depending on the potential: 1 $G_{0}$ ($G_{0}$ = $2e^{2}/h$), 0.5\n$G_{0}$ and not-well defined values below 1 $G_{0}$ were shown when the\npotential of the contact was kept at -0.6 V (double layer potential), -1.0 V\n(hydrogen evolution potential), and 0.8 V (oxide formation potential) versus\nAg/AgCl in 0.1 M Na$_{2}$SO$_{4}$ solution, respectively. These three\nreversible states and their respective conductances could be fully controlled\nby the electrochemical potential. These changes in the conductance values are\ndiscussed based on the proposed structure models of hydrogen adsorbed and\noxygen incorporated on an Au mono atomic contact.",
        "positive": "Phase Field Crystal Model for Magneto-Elasticity in Isotropic\n  Ferromagnetic Solids: A new isotropic magneto-elastic phase field crystal (PFC) model to study the\nrelation between morphological structure and magnetic properties of pure\nferromagnetic solids is introduced. Analytic calculations were used to\ndetermine the phase diagram and obtain the relationship between elastic strains\nand magnetization. Time dependent numerical simulations were used to\ndemonstrate the effect of grain boundaries on the formation of magnetic\ndomains. It was shown that the grain boundaries act as nucleating sites for\ndomains of reverse magnetization. Finally, we derive a relation for coercivity\nversus grain mis-orientation in the isotropic limit."
    },
    {
        "anchor": "Semimetal-to-semiconductor transition and charge-density-wave melting in\n  $1T$-TiSe$_{2-x}$S$_x$ single crystals: The transition metal dichalcogenide $1T$-TiSe$_2$ is a quasi-two-dimensional\nlayered material with a phase transition towards a commensurate charge density\nwave (CDW) at a critical temperature T$_{c}\\approx 200$K. The relationship\nbetween the origin of the CDW instability and the semimetallic or\nsemiconducting character of the normal state, i.e., with the non-reconstructed\nFermi surface topology, remains elusive. By combining angle-resolved\nphotoemission spectroscopy (ARPES), scanning tunneling microscopy (STM), and\ndensity functional theory (DFT) calculations, we investigate\n$1T$-TiSe$_{2-x}$S$_x$ single crystals. Using STM, we first show that the\nlong-range phase coherent CDW state is stable against S substitutions with\nconcentrations at least up to $x=0.34$. The ARPES measurements then reveal a\nslow but continuous decrease of the overlap between the electron and hole\n($e$-$h$) bands of the semimetallic normal-state well reproduced by DFT and\nrelated to slight reductions of both the CDW order parameter and $T_c$. Our DFT\ncalculations further predict a semimetal-to-semiconductor transition of the\nnormal state at a higher critical S concentration of $x_c$=0.9 $\\pm$0.1, that\ncoincides with a melted CDW state in TiSeS as measured with STM. Finally, we\nrationalize the $x$-dependence of the $e$-$h$ band overlap in terms of\nisovalent substitution-induced competing chemical pressure and charge\nlocalization effects. Our study highlights the key role of the $e$-$h$ band\noverlap for the CDW instability.",
        "positive": "Engineering the microstructure and magnetism of La$_2$CoMnO$_6$ thin\n  films by tailoring oxygen stoichiometry: We report on the magnetic and structural properties of\nferromagnetic-insulating La$_2$CoMnO$_6$ thin films grown on top of (001) STO\nsubstrates by means of RF sputtering technique. Careful structural analysis, by\nusing synchrotron X-ray diffraction, allows identifying two different\ncrystallographic orientations that are closely related to oxygen stoichiometry\nand to the features (coercive fields and remanence) of the hysteresis loops.\nBoth Curie temperature and magnetic hysteresis turn out to be dependent on the\noxygen stoichiometry. In situ annealing conditions allow tailoring the oxygen\ncontent of the films, therefore controlling their microstructure and magnetic\nproperties."
    },
    {
        "anchor": "Thermal Runaway, Flash Sintering and Asymmetrical Microstructural\n  Development of ZnO and ZnO-Bi2O3 under Direct Currents: DC flash sintering of both pure and 0.5 mol. % Bi2O3-doped ZnO at a\nrelatively high activating field of 300 V/cm has been investigated. It is\ndemonstrated that even high-purity ZnO single crystals can \"flash\" at 870C. In\ncomparison, flash sintering occurs at a substantially lower onset temperature\nof 550C in ZnO powder specimens, indicating the important roles of surfaces\nand/or grain boundaries. A model has been developed to forecast the thermal\nrunaway conditions and the predictions are in excellent agreements with the\nobserved onset flash temperatures, attesting that the flash starts as a thermal\nrunaway in at least these ZnO based systems. Interestingly, enhanced grain\ngrowth is observed at the anode side of the pure ZnO specimens with an abrupt\nchange in the grain sizes, indicating the occurrence of\nelectric-potential-induced abnormal grain growth. With a large current density,\nthe growth of aligned hexagonal single-crystalline rods toward the anode\ndirection is evident in the ZnO powder specimen. Moreover, Bi2O3 doping defers\nthe onset of flash sintering, which can be explained from the formation of\nspace charges at grain boundaries, and it homogenizes the microstructure due to\na liquid-phase sintering effect. The key scientific contributions of this study\ninclude the development of a model to predict the thermal runaway conditions\nthat are coincident with the observed onset flash sintering temperatures, the\nclarification of how flash starts in ZnO based specimens, and the observation\nand explanation of diversifying phenomena of sintering and microstructural\ndevelopment under applied electric currents.",
        "positive": "Theoretical prediction of MoN2 monolayer as a high capacity electrode\n  material for metal ion batteries: Benefited from the advantages on environmental benign, easy purification, and\nhigh thermal stability, the recently synthesized two-dimensional (2D) material\nMoN2 shows great potential for clean and renewable energy applications. Here,\nthrough first-principles calculations, we show that the monolayered MoN2 is\npromising to be a high capacity electrode material for metal ion batteries.\nFirstly, identified by phonon dispersion and exfoliation energy calculations,\nMoN2 monolayer is proved to be structurally stable and could be exfoliated from\nits bulk counterpart in experiments. Secondly, all the studied metal atoms (Li,\nNa and K) can be adsorbed on MoN2 monolayer, with both pristine and doped MoN2\nbeing metallic. Thirdly, the metal atoms possess moderate/low migration\nbarriers on MoN2, which ensures excellent cycling performance as a battery\nelectrode. In addition, the calculated average voltages suggest that MoN2\nmonolayer is suitable to be a cathode for Li-ion battery and anodes for Na-ion\nand K-ion batteries. Most importantly, as a cathode for Li-ion battery, MoN2\npossesses a comparable average voltage but a 1-2 times larger capacity (432 mA\nh g-1) than usual commercial cathode materials; as an anode for Na-ion battery,\nthe theoretical capacity (864 mA h g-1) of MoN2 is 2-5 times larger than\ntypical 2D anode materials such as MoS2 and most MXenes. Finally we also\nprovide an estimation of capacities for other transition-metal dinitrides\nmaterials. Our work suggests that the transition-metal dinitrides MoN2 is an\nappealing 2D electrode materials with high storage capacities."
    },
    {
        "anchor": "TiO2 based Nanostructured Memristor for RRAM and Neuromorphic\n  Applications: A Simulation Approach: We report simulation of nanostructured memristor device using piecewise\nlinear and nonlinear window functions for RRAM and neuromorphic applications.\nThe linear drift model of memristor has been exploited for the simulation\npurpose with the linear and non-linear window function as the mathematical and\nscripting basis. The results evidences that the piecewise linear window\nfunction can aptly simulate the memristor characteristics pertaining to RRAM\napplication. However, the nonlinear window function could exhibit the nonlinear\nphenomenon in simulation only at the lower magnitude of control parameter. This\nhas motivated us to propose a new nonlinear window function for emulating the\nsimulation model of the memristor. Interestingly, the proposed window function\nis scalable up to f(x)=1 and exhibits the nonlinear behavior at higher\nmagnitude of control parameter. Moreover, the simulation results of proposed\nnonlinear window function are encouraging and reveals the smooth nonlinear\nchange from LRS to HRS and vice versa and therefore useful for the neuromorphic\napplications.",
        "positive": "Thermal engineering in low-dimensional quantum devices: a tutorial\n  review of nonequilibrium Green's function methods: Thermal engineering of quantum devices has attracted much attention since the\ndiscovery of quantized thermal conductance of phonons. Although easily\nsubmerged in numerous excitations in macro-systems, quantum behaviors of\nphonons manifest in nanoscale low-dimensional systems even at room temperature.\nEspecially in nano transport devices, phonons move quasi-ballistically when the\ntransport length is smaller than their bulk mean free paths. It has been shown\nthat phonon nonequilibrium Green's function method (NEGF) is effective for the\ninvestigation of nanoscale quantum transport of phonons. In this tutorial\nreview two aspects of thermal engineering of quantum devices are discussed\nusing NEGF methods. One covers transport properties of pure phonons; the other\nconcerns the caloritronic effects, which manipulate other degrees of freedom,\nsuch as charge, spin, and valley, via the temperature gradient. For each part,\nwe outline basic theoretical formalisms first, then provide a survey on related\ninvestigations on models or realistic materials. Particular attention is given\nto phonon topologies and a generalized phonon NEGF method. Finally, we conclude\nour review and summarize with an outlook."
    },
    {
        "anchor": "Combining linear-scaling quantum transport and machine-learning\n  molecular dynamics to study thermal and electronic transports in complex\n  materials: We propose an efficient approach for simultaneous prediction of thermal and\nelectronic transport properties in complex materials. Firstly, a highly\nefficient machine-learned neuroevolution potential is trained using reference\ndata from quantum-mechanical density-functional theory calculations. This\ntrained potential is then applied in large-scale molecular dynamics\nsimulations, enabling the generation of realistic structures and accurate\ncharacterization of thermal transport properties. In addition, molecular\ndynamics simulations of atoms and linear-scaling quantum transport calculations\nof electrons are coupled to account for the electron-phonon scattering and\nother disorders that affect the charge carriers governing the electronic\ntransport properties. We demonstrate the usefulness of this unified approach by\nstudying thermoelectric transport properties of a graphene antidot lattice.",
        "positive": "Origins of electromagnetic anisotropy in monolayer black phosphorus: Contrary to empirical observations, lowest-order $k\\cdot\\hat{p}$ theory\npredicts that monolayer black phosphorus (\"phosphorene\") is completely immune\nto zigzag-polarized optical excitation at the bandgap energy. Using symmetry\narguments, we derive a $2\\times2$ Hamiltonian under the $k\\cdot\\hat{p}$\nformalism including higher-order corrections, which is used to show that the\nexperimentally-measured band-gap transition with zigzag polarization is\ndominated by the third order $k\\cdot\\hat{p}$ perturbation in the interband\noptical matrix element, whereas the effects of spin-orbit interaction are\nnegligible in this material, consistent with a trivial orbital diamagnetic\ncontribution to the $\\textit{g}$-factor."
    },
    {
        "anchor": "Linear Algebraic Calculation of Green's function for Large-Scale\n  Electronic Structure Theory: A linear algebraic method named the shifted\nconjugate-orthogonal-conjugate-gradient method is introduced for large-scale\nelectronic structure calculation. The method gives an iterative solver\nalgorithm of the Green's function and the density matrix without calculating\neigenstates.The problem is reduced to independent linear equations at many\nenergy points and the calculation is actually carried out only for a single\nenergy point. The method is robust against the round-off error and the\ncalculation can reach the machine accuracy. With the observation of residual\nvectors, the accuracy can be controlled, microscopically, independently for\neach element of the Green's function, and dynamically, at each step in\ndynamical simulations. The method is applied to both semiconductor and metal.",
        "positive": "Optimal design of auxetic hexachiral metamaterials with local resonators: A parametric beam lattice model is formulated to analyse the propagation\nproperties of elastic in-plane waves in an auxetic material based on a\nhexachiral topology of the periodic cell, equipped with inertial local\nresonators. The Floquet-Bloch boundary conditions are imposed on a reduced\norder linear model in the only dynamically active degrees-offreedom. Since the\nresonators can be designed to open and shift band gaps, an optimal design,\nfocused on the largest possible gap in the low-frequency range, is achieved by\nsolving a maximization problem in the bounded space of the significant\ngeometrical and mechanical parameters. A local optimized solution, for a the\nlowest pair of consecutive dispersion curves, is found by employing the\nglobally convergent version of the Method of Moving asymptotes, combined with\nMonte Carlo and quasi-Monte Carlo multi-start techniques."
    },
    {
        "anchor": "Electronic properties of A2Zr2O7 (A= Gd, Nd) ceramic: The density functional theory with generalized gradient approximation has\nbeen used to investigate the electronic structure of gadolinium pyrochlore\nA2Zr2O7 (A=Gd, Nd) ceramic synthesized in polycrystalline form by solid state\nreaction. Structural characterization of the compound was done through X-ray\ndiffraction (XRD) followed by Rietveld analysis of the XRD pattern. The Zr-K\nedge X-ray absorption (XAFS) spectra of A2Zr2O7 (A=Gd, Nd) were analysed\ntogether with those Zr-foil, which was used as reference compounds. X-ray\nphotoemission spectroscopy (XPS), X-ray absorption near edge structure (XANES)\nand extended X-ray absorption fine structure (EXAFS) for A2Zr2O7 (A=Gd, Nd) has\nbeen employed to obtain quantitative structural information on the Zr-local\nenvironment. The band gap is estimated using UV-Vis spectroscopy. The crystal\nstructure is face centered cubic, space group being Fd-3m (No. 227). The total\nenergies in this work were calculated using the generalized gradient\napproximation to DFT plus on-site repulsion (U) method.",
        "positive": "Drop-coated Titanium Dioxide Memristors: The fabrication of memristors by drop-coating sol-gel Ti(OH)$_4$ solution\nonto either aluminium foil or sputter-coated aluminium on plastic is presented.\nThe gel layer is thick, 37$\\mu$m, but both devices exhibit good memristance I-V\nprofiles. The drop coated aluminium foil memristors compare favourably with the\nsputter-coated ones, demonstrating an expansion in the accessibility of\nmemristor fabrication. A comparison between aluminium and gold for use as the\nsputter-coated electrodes shows that aluminium is the better choice as using\ngold leads to device failure. The devices do not require a forming step."
    },
    {
        "anchor": "Dissolution and Recrystallization Behavior of Li3PS4 in Different\n  Organic Solvents: Solid state batteries can be built based on thiophosphate electrolytes such\nas beta-Li3PS4. For the preparation of these electrolytes, various\nsolvent-based routes have been reported. For recycling of end-of-life solid\nstate batteries based on such thiophosphates, we consider the development of\ndissolution and recrystallization strategies for the recovery of the model\ncompound beta-Li3PS4. We show that recrystallization can only be performed in\npolar, slightly protic solvents such as N-methylformamide (NMF). The\nrecrystallization is comprehensively studied, showing that it proceeds via an\nintermediate phase with composition Li3PS4*2NMF, which is structurally\ncharacterized. This phase has a high resistivity for the transport of lithium\nions and must be removed in order to obtain a recrystallized product with a\nconductivity similar to the pristine material. Moreover, the recrystallization\nfrom solution results in an increase of the amorphous phase fraction next to\ncrystalline beta-Li3PS4, which results in a decrease of the activation energy\nto 0.2 eV compared to 0.38 eV for the pristine phase.",
        "positive": "Role of sonication pre-treatment and cation valence in nano-cellulose\n  suspensions sol-gel transition: Sol-gel transition of carboxylated cellulose nanocrystals is investigated\nusing rheology, SAXS, NMR and optical spectroscopies to unveil the distinctive\nroles of ultrasounds treatment and ions addition. Besides cellulose fibers\nfragmentation, sonication treatment induces fast gelling of the solution.\nGelation is induced independently on the addition of cations, while the final\nrheological properties are highly influenced by the type, the concentration as\nwell as on the sequence of the operations since salts must be added before\nsonication to produce stiff gels. Cations with various charge and dimension\nhave been associated to ultrasounds to induce gelation and the gel elastic\nmodulus increase proportionally with the charge over the ion size ratio. SAXS\nanalysis of the Na+ hydrogel and Ca2+ hydrogel to which the ion was added after\nsonication shows the presence of structurally ordered domains where water is\nconfined as indicated by 1H-NMR investigation of the dynamic of water exchange\nin the hydrogels. Conversely, separated phases containing essentially free\nwater, characterize the hydrogels obtained by sonication after Ca2+ addition,\nconfirming that this ion induces irreversible fiber aggregation. The\nrheological properties of the hydrogels depend on the duration of the\nultrasound treatment and it enables the design of materials programmed with\ntailored energy dissipation response."
    },
    {
        "anchor": "Structure and magnetic properties of nanocrystalline PrCo3: The structure and magnetic properties of nanocrystalline PrCo$_3$ prepared by\nhigh-energy milling technique have been investigated by means of X-ray\ndiffraction using the Rietveld method coupled to Curie temperature and magnetic\nmeasurements. The as-milled samples were subsequently annealed in temperature\nrange from 750 to 1050 {\\deg}C for 30 min to optimize the extrinsic properties.\nFrom x-ray studies of magnetic aligned samples, the magnetic anisotropy of this\ncompounds is found uniaxial. The Curie temperature is 349 {\\deg}K and no\nsaturation reached at room temperature for applied field of 90 kOe. The\ncoercive field of 55 kOe and 12 kOe measured at 10 and 293 K respectively is\nobtained after annealing at 750 {\\deg}C for 30 min suggests that\nnanocrystalline PrCo$_3$ are interesting candidates in the field of permanent\nmagnets. We have completed this experimental study by simulations in the\nmicromagnetic framework in order to get a qualitative picture of the\nmicrostructure effect on the macroscopic magnetization curve. From this simple\nmodel calculation, we can suggest that the after annealing the system behaves\nas magnetically hard crystallites embedded in a weakly magnetized amorphous\nmatrix. PACS : 75.50.Bb, 75.50.Tt, 76.80.+y",
        "positive": "Elastic constants and volume changes associated with two high-pressure\n  rhombohedral phase transformations in vanadium: We present results from ab initio calculations of the mechanical properties\nof the rhombohedral phase (beta) of vanadium metal reported in recent\nexperiments, and other predicted high-pressure phases (gamma and bcc), focusing\non properties relevant to dynamic experiments. We find that the volume change\nassociated with these transitions is small: no more than 0.15% (for beta -\ngamma). Calculations of the single crystal and polycrystal elastic moduli\n(stress-strain coefficients) reveal a remarkably small discontinuity in the\nshear modulus and other elastic properties across the phase transitions even at\nzero temperature where the transitions are first order."
    },
    {
        "anchor": "Energy surface and lifetime of magnetic skyrmions: The stability of skyrmions in various environments is estimated by analyzing\nthe multidimensional surface describing the energy of the system as a function\nof the directions of the magnetic moments in the system. The energy is given by\na Heisenberg-like Hamiltonian that includes Dzyaloshinskii-Moriya interaction,\nanisotropy and external magnetic field. Local minima on this surface correspond\nto the ferromagnetic and skyrmion states. Minimum energy paths (MEP) between\nthe minima are calculated using the geodesic nudged elastic band method. The\nmaximum energy along an MEP corresponds to a first order saddle point on the\nenergy surface and gives an estimate of the activation energy for the magnetic\ntransition, such as creation and annihilation of a skyrmion. The\npre-exponential factor in the Arrhenius law for the rate, the so-called attempt\nfrequency, is estimated within harmonic transition state theory where the\neigenvalues of the Hessian at the saddle point and the local minima are used to\ncharacterize the shape of the energy surface. For some degrees of freedom,\nso-called 'zero modes', the energy of the system remains invariant. They need\nto be treated separately and give rise to temperature dependence of the attempt\nfrequency. As an example application of this general theory, the lifetime of a\nskyrmion in a track of finite width for a PdFe overlayer on a Ir(111) substrate\nis calculated as a function of track width and external magnetic field. Also,\nthe effect of non-magnetic impurities is studied. Various MEPs for annihilation\ninside a track, via the boundary of a track and at an impurity are presented.\nThe attempt frequency as well as the activation energy has been calculated for\neach mechanism to estimate the transition rate as a function of temperature.",
        "positive": "Proton-driven patterning of bulk transition metal dichalcogenides: At the few-atom-thick limit, transition metal dichalcogenides (TMDs) exhibit\na host of attractive electronic optical, and structural properties. The\npossibility to pattern these properties has a great impact on applied and\nfundamental research. Here, we demonstrate spatial control over the light\nemission, lattice deformation, and hydrogen storage in bulk TMDs. By low-energy\nproton irradiation, we create uniquely favorable conditions for the production\nand accumulation of molecular hydrogen just one or few monolayers beneath the\ncrystal basal plane of bulk WS2, WSe2, WTe2, MoSe2, and MoS2 samples. H2\ntherein produced coalesces to form bubbles, which lead to the localized\nswelling of one X-M-X plane prevalently. This results eventually in the\ncreation of atomically thin domes filled with molecular hydrogen at 10 atm. The\ndomes emit light strongly well above room temperature and can store H2\nindefinitely. They can be produced with the desired density, well-ordered\npositions, and size tunable from the nanometer to the micrometer scale, thus\nproviding a template for the manageable and durable mechanical and electronic\nstructuring of two-dimensional materials."
    },
    {
        "anchor": "Methods of electron transport in ab initio theory of spin stiffness: We present an ab initio theory of the spin-wave stiffness tensor for ordered\nand disordered itinerant ferromagnets with pair exchange interactions derived\nfrom a method of infinitesimal spin rotations. The resulting formula bears an\nexplicit form of a linear-response coefficient which involves one-particle\nGreen's functions and effective velocity operators encountered in a recent\ntheory of electron transport. Application of this approach to ideal metal\ncrystals yields more reliable values of the spin stiffness than traditional\nill-convergent real-space lattice summations. The formalism can also be\ncombined with the coherent potential approximation for an effective-medium\ntreatment of random alloys, which leads naturally to an inclusion of\ndisorder-induced vertex corrections to the spin stiffness. The calculated\nconcentration dependence of the spin-wave stiffness of random fcc Ni-Fe alloys\ncan be ascribed to a variation of the reciprocal value of alloy magnetization.\nCalculations for random iron-rich bcc Fe-Al alloys reveal that their spin-wave\nstiffness is strongly reduced owing to the atomic ordering; this effect takes\nplace due to weakly coupled local magnetic moments of Fe atoms surrounded by a\nreduced number of Fe nearest neighbors.",
        "positive": "Isotopic effect of proton conductivity in barium-zirconates for various\n  hydrogen-containing atmospheres: Among various perovskite proton conducting oxides, Y-doped BaZrO3 perovskite\nis a promising material for electrochemical hydrogen devices due to the good\nchemical stability and higher proton conductivity at higher operating\ntemperatures like 500-800 {\\deg}C. For the practical application of the\nfunctional BaZrO3 proton conductor in the electrochemical hydrogen devices, its\nnecessary to understand the isotopic effect of proton conductivity. To\nunderstand the isotopic effect of proton conductivity in the barium zirconates,\nin this study, the proton conductivity in the Ar, (Ar + 4% H2), (Ar + 4% D2),\n(Ar + H2O), (Ar + D2O), and O2 atmospheres were measured for two different\ncompositions: BaZr0.9Y0.1O2.95 (BZY), and BaZr0.955Y0.03Co0.015O2.97 (BZYC) in\nthe temperature range from 500 {\\deg}C to 1000 {\\deg}C. By comparing the\nobtained results, a significant difference in sinterability, conductivity, and\nthe isotopic effect was observed due to the co-doping of the Co element in the\nBaZr1-xYxO3-a proton conductor."
    },
    {
        "anchor": "Phonon Invisibility Driven by Robust Magneto-Elastic Coupling in AlFeO3\n  Thin Film: The thin films of lead free magneto-electric compound AlFeO3 have been\ndeposited using pulsed laser deposition technique. X-ray diffraction, X-ray\nabsorption spectroscopy and reflectivity measurements established the\northorhombic structure and material density of 4.5g/cc which is comparable with\nbulk AlFeO3. The Raman mode corresponding to AlFeO3 was found to vanish when\nmagnetic field of 800 Oe was applied at room temperature. Additionally, it was\nobserved that the Raman phonon mode present at the room temperature becomes\ninvisible in the temperature window of 280K-236K and reappears below it. The\ndetailed analysis of magnetization showed a change in magnetic order in this\ntemperature interval. The invisibility of Raman phonon mode corresponding to\nAlFeO3 have been attributed to the lattice deformation caused by the\nmagnetoelastic effect. The presence of strong spin-lattice coupling is also\nvalidated by the renormalization of phonon frequencies below 200 K.",
        "positive": "Tunability of solitary wave properties in one dimensional strongly\n  nonlinear phononic crystals: One dimentional strongly nonlinear phononic crystals were assembled from\nchains of PTFE (polytetrafluoroethylene) and stainless steel spheres with\ngauges installed inside the beads. Trains of strongly nonlinear solitary waves\nwere excited by an impact. A significant modification of the signal shape and\nan increase of solitary wave speed up to two times (at the same amplitude of\ndynamic contact force)were achieved through a noncontact magnetically induced\nprecompression of the chains. Data for PTFE based chains are presented for the\nfirst time and data for stainless steel based chains were extended into a\nsmaller range of amplitudes by more than one order of magnitude than previously\nreported. Experimental results were found to be in reasonable agreement with\nthe long wave approximation and with numerical calculations based on Hertz\ninteraction law for discrete chains."
    },
    {
        "anchor": "General time-reversal equivariant neural network potential for magnetic\n  materials: This study introduces time-reversal E(3)-equivariant neural network and\nSpinGNN++ framework for constructing a comprehensive interatomic potential for\nmagnetic systems, encompassing spin-orbit coupling and noncollinear magnetic\nmoments. SpinGNN++ integrates multitask spin equivariant neural network with\nexplicit spin-lattice terms, including Heisenberg, Dzyaloshinskii-Moriya,\nKitaev, single-ion anisotropy, and biquadratic interactions, and employs\ntime-reversal equivariant neural network to learn high-order spin-lattice\ninteractions using time-reversal E(3)-equivariant convolutions. To validate\nSpinGNN++, a complex magnetic model dataset is introduced as a benchmark and\nemployed to demonstrate its capabilities. SpinGNN++ provides accurate\ndescriptions of the complex spin-lattice coupling in monolayer CrI$_3$ and\nCrTe$_2$, achieving sub-meV errors. Importantly, it facilitates large-scale\nparallel spin-lattice dynamics, thereby enabling the exploration of associated\nproperties, including the magnetic ground state and phase transition.\nRemarkably, SpinGNN++ identifies a new ferrimagnetic state as the ground\nmagnetic state for monolayer CrTe2, thereby enriching its phase diagram and\nproviding deeper insights into the distinct magnetic signals observed in\nvarious experiments.",
        "positive": "Nanoscale heterogeneity at the aqueous electrolyte-electrode interface: Using molecular dynamics simulations, we reveal emergent properties of\nhydrated electrode interfaces that while molecular in origin are integral to\nthe behavior of the system across long times scales and large length scales.\nSpecifically, we describe the impact of a disordered and slowly evolving\nadsorbed layer of water on the molecular structure and dynamics of the\nelectrolyte solution adjacent to it. Generically, we find that densities and\nmobilities of both water and dissolved ions are spatially heterogeneous in the\nplane parallel to the electrode over nanosecond timescales. These and other\nrecent results are analyzed in the context of available experimental literature\nfrom surface science and electrochemistry. We speculate on the implications of\nthis emerging microscopic picture on the catalytic proficiency of hydrated\nelectrodes, offering an new direction for study in heterogeneous catalysis at\nthe nanoscale."
    },
    {
        "anchor": "Phonon-assisted spin splitting in centrosymmetric crystals: For static crystals it is well known that electronic states are doubly\ndegenerate in their spin degree of freedom in the presence of time reversal and\ninversion symmetries. This degeneracy can only be lifted by either (i) breaking\ntime reversal symmetry, for example in a ferromagnet, or (ii) breaking\ninversion symmetry and having spin orbit coupling, for example in the Rashba\neffect. We propose that spin degeneracy can be lifted in time reversal and\ninversion symmetric crystals with a combination of lattice vibrations and\nspin-orbit coupling. We demonstrate this effect in the cubic perovskite\nCsPbCl$_3$ by performing first principles calculations of the finite\ntemperature band structure, which, in accordance with our prediction, undergoes\nspin splitting. We also suggest optical and photoemission experiments to\nexamine our predictions. This new understanding dramatically expands the range\nof materials that can exhibit spin splitting, with potential applications in a\nvariety of technologies such as spintronics and photovoltaics.",
        "positive": "Magneli-Phases in Anatase Strongly Promote Co-Catalyst-Free\n  Photocatalytic Hydrogen Evolution: Magneli phases of titanium dioxide (such as Ti4O7, Ti5O9, etc.) provide\nelectronic properties, namely a stable metallic behavior at room temperature.\nIn this manuscript, we demonstrate that nanoscopic Magneli phases, formed\nintrinsically in anatase during a thermal aerosol synthesis, can enable\nsignificant photocatalytic H2 generation. This without the use of any extrinsic\nco-catalyst in anatase. Under optimized conditions, mixed phase particles of 30\npercent anatase, 25 percent Ti4O7 and 20 percent Ti5O9 are obtained that can\nprovide, under solar light, direct photocatalytic H2 evolution at a rate of 145\nmicromol h-1 g-1. These anatase particles contain 5-10 nm size inter-grown\nphases of Ti4O7 and Ti5O9. Key is the metallic band of Ti4O7 that induces a\nparticle internal charge separation and transfer cascade with suitable\nenergetics and favorable dimensions that are highly effective for H2\ngeneration."
    },
    {
        "anchor": "Laser studies of metallic artworks: Museum curators and archaeologists use analytical science to provide\nimportant information on artworks and objects. For example, scientific\ntechniques provide information on artwork elemental composition, origin and\nauthenticity, and corrosion products, while also finding use in the day-to-day\nconservation of many historical objects in museums and archaeological sites\naround the world. In this work two special cases are being discussed. In the\nfirst part of our work, physicochemical studies of an icon on a metal substrate\nwere carried out using non-destructive, qualitative analysis of pigments and\norganic-based binding media, employing various microscopic and analytical\ntechniques, such as Optical Fluorescence Microscopy, XRF, and Gas\nChromatography. In the second part of our work, laser cleaning of late Roman\ncoins has been performed using a Q-switched Nd:YAG laser (1064 nm, 6 ns) and a\nGaAlAs diode laser (780 nm, 90 ps). The corrosion products have been removed,\nwhile we observe increased concentrations in Ag, which is the main material of\nthe silvering plating found in late Roman coins.",
        "positive": "Effects of bulk and interfacial anharmonicity on thermal conductance at\n  solid/solid interfaces: We present the results of classical molecular dynamics simulations to assess\nthe relative contributions to interfacial thermal conductance from inelastic\nphonon processes at the interface and in the adjacent bulk materials. The\nsimulated system is the prototypical interface between argon and \"heavy argon\"\ncrystals, which enables comparison with many past computational studies. We run\nsimulations interchanging the Lennard-Jones potential with its harmonic\napproximation to test the effect of anharmonicity on conductance. The results\nconfirm that the presence of anharmonicity is correlated with increasing\nthermal conductance with temperature, which supports conclusions from prior\nexperimental and theoretical work. However, in the model Ar/heavy-Ar system,\nanharmonic effects at the interface itself contribute a surprisingly small part\nof the total thermal conductance. The larger fraction of the thermal\nconductance at high temperatures arises from anharmonic effects away from the\ninterface. These observations are supported by comparisons of the spectral\nenergy density, which suggest that bulk anharmonic processes increase\ninterfacial conductance by thermalizing energy from modes with low transmission\nto modes with high transmission."
    },
    {
        "anchor": "Enhanced Seebeck effect in graphene devices by strain and doping\n  engineering: In this work, we investigate the possibility of enhancing the thermoelectric\npower (Seebeck coefficient) in graphene devices by strain and doping\nengineering. While a local strain can result in the misalignment of Dirac cones\nof different graphene sections in the k-space, doping engineering leads to\ntheir displacement in energy. By combining these two effects, we demonstrate\nthat a conduction gap as large as a few hundreds meV can be achieved and hence\nthe enhanced Seebeck coefficient can reach a value higher than 1.4 mV/K in\ngraphene doped heterojunctions with a locally strained area. Such\nhetero-channels appear to be very promising for enlarging the applications of\ngraphene devices as in strain and thermal sensors.",
        "positive": "Architectural bone parameters and the relationship to titanium lattice\n  design for powder bed fusion additive manufacturing: Additive manufacturing (AM) of titanium (Ti) and Ti-6Al-4V lattices has been\nproposed for bone implants and augmentation devices. Ti and Ti-6Al-4V have\nfavourable biocompatibility, corrosion resistance and fatigue strength for bone\napplications; yet, the optimal parameters for Ti-6Al-4V lattice designs\ncorresponding to the natural micro- and meso-scale architecture of human\ntrabecular and cortical bone are not well understood. A comprehensive review\nwas completed to compare the natural lattice architecture properties in human\nbone to Ti and Ti-6Al-4V lattice structures for bone replacement and repair. Ti\nand Ti-6Al-4V lattice porosity has varied from 15% to 97% with most studies\nreporting a porosity between 50-70%. Cortical bone is roughly 5-15% porous and\nlattices with 50-70% porosity are able to achieve comparable stiffness,\ncompressive strength, and yield strength. Trabecular bone has a reported\nporosity range from 70-90%, with trabecular thickness varying from 120-200\n{\\mu}m. Existing powder bed fusion technologies have produced strut and wall\nthicknesses ranging from 200-1669 {\\mu}m. This suggests limited overlap between\ncurrent AM of Ti and Ti-6Al-4V lattice structures and trabecular bone\narchitecture, indicating that replicating natural trabecular bone parameters\nwith latticing is prohibitively challenging. This review contributes to the\nbody of knowledge by identifying the correspondence of Ti and Ti-6Al-4V\nlattices to the natural parameters of bone microarchitectures, and provides\nfurther guidance on the design and AM recommendations towards addressing\nrecognized performance gaps with powder bed fusion technologies."
    },
    {
        "anchor": "Existence of inter coupled structural, electronic and magnetic states in\n  Sm$ _{2} $NiMnO$ _{6} $ double perovskite: Coupling between different interactions allows to control physical aspects in\nmultifunctional materials by perturbing any of the degrees of freedom. Here, we\naim to probe the correlation among structural, electronic and magnetic\nobservables of Sm$ _{2} $NiMnO$ _{6} $ ferromagnetic insulator double\nperovskite. Our employed methodology includes thermal evolution of synchrotron\nX-ray diffraction, near edge and extended edge hard X-ray absorption\nspectroscopy and bulk magnetometry. The magnetic ordering in SNMO adopts two\ntransitions, at T$ _{C} $=159.6K due to ferromagnetic arrangement of Ni-Mn\nsublattice and at T$ _{d} $=34.1K because of anti-parallel alignment of\npolarized Sm paramagnetic moments with respect to Ni-Mn network. The global as\nwell as local crystal structure of SNMO undergoes isostructural transitions\nacross T$ _{C} $ and T$ _{d} $, observed by means of temperature dependent\nvariation in Ni/Mn-O, Ni-Mn bonding characters and super exchange angle in\nNi-O-Mn linkage. Hybridization between Ni, Mn 3\\textit{d}, O 2\\textit{p}\nelectronic states is also modified in the vicinity of magnetic transition. On\nthe other hand, the signature of Ni/Mn anti-site disorders are evidenced from\nlocal structure and magnetization analysis. The change in crystal environments\ngoverns the magnetic response by imposing alteration in metal - ligand orbital\noverlap. Utilizing these complimentary probes we have found that structural,\nelectronic and magnetic states are inter-coupled in SNMO which makes it a\npotential platform for technological usage.",
        "positive": "On a three-dimensional lattice approach for modelling corrosion induced\n  cracking and its influence on bond between reinforcement and concrete: The present work involves the discrete modelling of corrosion induced\ncracking and its influence on the bond between reinforcement and concrete. A\nlattice approach is used to describe the mechanical interaction of a corroding\nreinforcement bar, the surrounding concrete and the interface between steel\nreinforcement and concrete. The cross-section of the ribbed reinforcement bar\nis taken to be circular, assuming that the interaction of the ribs of the\ndeformed reinforcement bar and the surrounding concrete is included in a\ncap-plasticity interface model. The expansion of the corrosion product is\nrepresented by an eigenstrain in the lattice elements forming the interface.\nThe lattice modelling approach is applied to the analysis of corrosion induced\ncracking and its influence of the bond strength. The model capabilities are\nassessed by comparing results of analyses with those from unconfined pull-out\ntests reported in the literature. Future work will investigate the influence of\nthe stiffness of interface elements and the effect of lateral confinement on\ncorrosion induced cracking."
    },
    {
        "anchor": "Acoustic Metameterial with Negative Modulus: We present experimental and theoretical results on an acoustic metamaterial\nthat exhibits negative effective modulus in a frequency range from 0 to 450 Hz.\nOne-dimensional acoustic metamaterial with an array of side holes on a tube was\nfabricated. We observed that acoustic waves above 450 Hz propagated well in\nthis structure, but no sound below 450 Hz passed through. The frequency\ncharacteristics of the metamaterial has the same form as that of the\npermittivity in metals due to the plasma oscillation. We also provide a theory\nto explain the experimental results.",
        "positive": "Shear-Exfoliated Phosphorene for Rechargeable Nanoscale Battery: Discovery of atomically thin black phosphorus (called phosphorene) holds\npromise to be used as an alternative two-dimensional material to graphene and\ntransition metal dichalcogenides especially as an anode material for\nlithium-ion batteries (LIBs). However, at present bulk black phosphorus (BP)\nstill suffers from rapid capacity fading that results in poor rechargeable\nperformance. Here, for the first time, we use in situ transmission electron\nmicroscopy (TEM) to construct nanoscale phosphorene LIBs and visualize the\ncapacity fading mechanism in thick multilayer phosphorene by real time\ncapturing delithiation-induced structural decomposition that reduces electrical\nconductivity and thus causes irreversibility of lithiated Li3P phase. We\nfurther demonstrate that few-layer phosphorene successfully circumvents the\nstructural decomposition and holds superior structural restorability, even\nsubjected to multi-cycle lithiation/delithiation processes and concomitant huge\nvolume expansion. This finding affords new experimental insights into\nthickness-dependent lithium diffusion kinetics in phosphorene. Additionally, a\nscalable liquid-phase shear exfoliation route has been developed to produce\nhigh-quality ultrathin (monolayer or few-layer) phosphorene, only by a\nhigh-speed shear mixer or even a household kitchen blender with the shear rate\nthreshold, which will pave the way for potential large-scale applications in\nLIBs once the rechargeable phosphorene nanoscale batteries can be transferred\nto industrialized enlargement in the future."
    },
    {
        "anchor": "Epitaxial UN and $\u03b1$-U$_2$N$_3$ Thin Films: Single crystal epitaxial thin films of UN and U$_2$N$_3$ have been grown for\nthe first time by reactive DC magnetron sputtering. These films provide ideal\nsamples for fundamental research into the potential accident tolerant fuel, UN,\nand U$_2$N$_3$, its intermediate oxidation product. Films were characterised\nusing x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS), with\nXRD analysis showing both thin films to be [001] oriented and composed of a\nsingle domain. The specular lattice parameters of the UN and U$_2$N$_3$ films\nwere found to be 4.895\\,\\AA{} and 10.72\\,\\AA{}, respectively, with the UN film\nhaving a miscut of 2.6\\,$^\\circ$. XPS showed significant differences in the\nN-1s peak between the two films, with area analysis showing both films to be\nstoichiometric.",
        "positive": "Nanoscale Magnetic Behavior Localization in Exchange Strength Modulated\n  Ferromagnets: Although ferromagnetism is in general a long-range collective phenomenon, it\nis possible to induce local spatial variations of magnetic properties in\nferromagnetic materials. For example, systematic variation of the exchange\ncoupling strength can be used to create systems that behave as if they are\ncomprised of virtually independent segments that exhibit \"local\" Curie\ntemperatures. Such localization of thermodynamic behavior leads to boundaries\nbetween strongly and weakly magnetized regions that can be controllably moved\nwithin the material with temperature. The utility of this interesting\nfunctionality is largely dependent on the inherent spatial resolution of\nmagnetic properties - specifically the distance over which the exchange\nstrength and corresponding properties behave locally. To test the degree to\nwhich this type of localization can be realized in materials, we have\nfabricated epitaxial films of Co[1-x]Ru[x] alloy featuring a nanometer scale\ntriangular wave-like concentration depth profile. Continuous nanoscale\nmodulation of the local Curie temperature was observed using polarized neutron\nreflectometry. These results are consistent with mean-field simulations of spin\nsystems that encompass the possibility of delocalized exchange coupling, and\nshow that composition grading can be used to localize magnetic properties in\nfilms down to the nanometer level. Since this is demonstrated here for an\nitinerant metal, we assert that for virtually any modulated magnetic material\nsystem, collective effects can be suppressed to length scales smaller than\nabout 3 nm, so that magnetic behavior overall can be well described in terms of\nlocal material properties."
    },
    {
        "anchor": "A quantized statistical model of flow stress and generalized Hall-Petch\n  law for deformable polycrystalline materials. A temperature-dimension effect: A theory of flow stress (FS), reviewing and developing our research,e.g.\narxiv:1803.08247;1908.09338, is proposed,including yield strength (YS) of PC\nmaterials for quasi-static plastic loading for grain of average size d in range\n10^{-8}-10^{-2}m. It's based on statistical model of energy spectrum\ndistribution in each grain of 1-mode PC sample under plastic loading,with\nhighest level equal to maximal dislocation energy. Found distribution of scalar\ndislocation density leads to FS due to Taylor strain hardening containing usual\nand anomalous HP laws for coarse and NC grains, respectively, and reaches\nmaximum for extreme grain size d_0 of order 10^{-8}m. Maximum undergoes shift\nto region of larger grains for decreasing T and increasing strains. Coincidence\nis established among theoretical and experimental data on YS for\nBCC(\\alpha-Fe), FCC(Cu,Al,Ni),HCP(\\alpha-Ti,Zr) PC materials at T=300K.The\nT-dependence of strength quantities is studied. It is shown using Al that YS\ngrows with decrease in T for all grains with d>3d_0,and then YS decreases in NC\nregion,thus determining a temperature-dimension effect (TDE).1-phase model of\nPC sample is extended by including softening GB phase into 2-phase model,and\nthen by dispersion (un)hardening. A quasi-particle interpretation of\ncrystallite energy quantization is suggested.Analytic and graphic forms of HP\nlaws are obtained in above samples with different values of small-,large-angle\nGB and constant pores.The maximum of YS and respective extremal grain size of\nthe samples are shifted by change of 2-nd phase.The T-dependence of YS in range\nof 150-350K for Al demonstrates the validity of TDE. An enlargement of 2-nd\nphase neutralizes TDE.Deformation curves for 1- and 2-mode 2-phase \\alpha-Fe PC\nmodel are constructed with Backofen-Considere fracture criterion,as compared to\nexperimental,1-phase model data, and strongly depend on multimodality and GB",
        "positive": "P-type polar transition of chemically doped multilayer MoS2 transistor: The accessibility of both n-type and p-type MoS2 FET is necessary for\ncomplementary device applications involving MoS2. However, MoS2 PFET is rarely\nachieved due to pinning effect resulting high Rc at metal-MoS2 interface and\nthe inherently strong n-type property of the MoS2 material. In this study, we\nrealized a high-performance multi-layer MoS2 PFET via controllable chemical\ndoping, which has an excellent on/off ratio of 107 and a maximum hole mobility\nof 72 cm2/Vs at room temperature, and these values are further exceeding to 109\nand 132 cm2/Vs at 133K. In addition, we revealed that large Rc hindered the\npolar transition of MoS2 FET from n-type to p-type, meanwhile channel Rs\nlimited Ion of PFET. Therefore it is suggested that reducing Rc at high work\nfunction metal-MoS2 interface and p-type doping of channel were necessary for\nachieving high performance MoS2 PFET. Based on the high performance PFET, we\nsuccessfully demonstrated a MoS2 CMOS inverter by integrating NFET and PFET."
    },
    {
        "anchor": "Double lattice potential for molecular dynamics simulation of silicon\n  with demonstrated validity: To reproduce the diamond structure of silicon, double lattice (DL) potential\nconstructed from two interatomic potentials for face centered cubic (fcc)\nlattice, is proposed for molecular dynamics (MD) simulations. For the validity\ntest of MD simulation, the Tersoff potential, the Stillinger and Weber (SW)\npotential, the environment-dependent interatomic (EDI) potential, the charge\noptimized many-body (COMB) potential, and the modified embedded-atom (MEAM)\npotential have been also employed for comparison. The crystal lattice of\nsimulated silicon system is identified by calculating the distribution\nfunctions of the distances between the atoms and the angles between the lines\nlinking an atom with its nearest neighbors. The results are also compared with\nthe perfect silicon crystal. The crystal lattice, the crystallization\ntemperature, and elastic constants have been calculated from MD simulations\nusing above potentials. The results show that the systems with modified\nTersoff, SW, EDI, COMB, and MEAM potentials could not exhibit the diamond\nstructure and only the DL potential gives diamond lattice. The ground state for\nDL potential is the wurtzite structure, and the metastable state formed during\nrapid cooling is the cubic diamond structure. The physical parameters obtained\nfrom the simulation with DL potential are in agreement with the experiment\nresults. This work indicated that only DL potential is valid for MD simulation\nof silicon crystal among above various potentials.",
        "positive": "Giant shape-memory effect in twisted ferroic nanocomposites: The shape recovery ability of shape-memory alloys vanishes below a critical\nsize (~50nm), which prevents their practical applications at the nanoscale. In\ncontrast, ferroic materials, even when scaled down to dimensions of a few\nnanometers, exhibit actuation strain through domain switching, though the\ngenerated strain is modest (~1%). Here, we develop free-standing twisted\narchitectures of nanoscale ferroic oxides showing shape-memory effect with a\ngiant recoverable strain (>10%). The twisted geometrical design amplifies the\nstrain generated during ferroelectric domain switching, which cannot be\nachieved in bulk ceramics or substrate-bonded thin films. The twisted ferroic\nnanocomposites allow us to overcome the size limitations in traditional\nshape-memory alloys and opens new avenues in engineering large-stroke\nshape-memory materials for small-scale actuating devices such as nanorobots and\nartificial muscle fibrils."
    },
    {
        "anchor": "Growth dynamics of vertically aligned single-walled carbon nanotubes\n  from in situ measurements: An in situ optical absorbance measurement was used to study the growth\ndynamics of vertically aligned single-walled carbon nanotubes (VA-SWCNTs)\nsynthesized by chemical vapor deposition of ethanol. The growth rate of the\nVA-SWCNT film was found to decay exponentially from an initial maximum,\nresulting in an effective growth time of approximately 15 minutes.\nInvestigation of various growth conditions revealed an optimum pressure at\nwhich growth is maximized, and this pressure depends on the growth temperature.\nBelow this optimum pressure the synthesis reaction is first-order, and the\nrate-limiting step is the arrival of ethanol at the catalyst. We also present a\nnovel method for determining the burning temperature of low-mass materials,\nwhich combines the in situ absorbance measurement with controlled oxidation.",
        "positive": "Giant and tunable valley degeneracy splitting in MoTe2: Monolayer transition-metal dichalcogenides possess a pair of degenerate\nhelical valleys in the band structure that exhibit fascinating optical valley\npolarization. Optical valley polarization, however, is limited by carrier\nlifetimes of these materials. Lifting the valley degeneracy is therefore an\nattractive route for achieving valley polarization. It is very challenging to\nachieve appreciable valley degeneracy splitting with applied magnetic field. We\npropose a strategy to create giant splitting of the valley degeneracy by\nproximity-induced Zeeman effect. As a demonstration, our first principles\ncalculations of monolayer MoTe$_2$ on a EuO substrate show that valley\nsplitting over 300 meV can be generated. The proximity coupling also makes\ninterband transition energies valley dependent, enabling valley selection by\noptical frequency tuning in addition to circular polarization. The valley\nsplitting in the heterostructure is also continuously tunable by rotating\nsubstrate magnetization. The giant and tunable valley splitting adds a readily\naccessible dimension to the valley-spin physics with rich and interesting\nexperimental consequences, and offers a practical avenue for exploring device\nparadigms based on the intrinsic degrees of freedom of electrons."
    },
    {
        "anchor": "Memory Effect in the Photoinduced Femtosecond Rotation of Magnetization\n  in the Ferromagnetic Semiconductor GaMnAs: We report a femtosecond response in photoinduced magnetization rotation in\nthe ferromagnetic semiconductor GaMnAs, which allows for detection of a\nfour-state magnetic memory at the femtosecond time scale. The temporal profile\nof this cooperative magnetization rotation exhibits a discontinuity that\nreveals two distinct temporal regimes, marked by the transition from a highly\nnon-equilibrium, carrier-mediated regime within the first 200 fs, to a thermal,\nlattice-heating picosecond regime.",
        "positive": "Short- and medium-range orders in Al90Tb10 glass and their relation to\n  the structures of competing crystalline phases: Molecular dynamics simulations using an interatomic potential developed by\nartificial neural network deep machine learning are performed to study the\nlocal structural order in Al90Tb10 metallic glass. We show that more than 80%\nof the Tb-centered clusters in Al90Tb10 glass have short-range order (SRO) with\ntheir 17 first coordination shell atoms stacked in a '3661' or '15551'\nsequence. Medium-range order (MRO) in Bergman-type packing extended out to the\nsecond and third coordination shells is also clearly observed. Analysis of the\nnetwork formed by the '3661' and '15551' clusters show that ~82% of such SRO\nunits share their faces or vertexes, while only ~6% of neighboring SRO pairs\nare interpenetrating. Such a network topology is consistent with the\nBergman-type MRO around the Tb-centers. Moreover, crystal structure searches\nusing genetic algorithm and the neural network interatomic potential reveal\nseveral low-energy metastable crystalline structures in the composition range\nclose to Al90Tb10. Some of these crystalline structures have the '3661' SRO\nwhile others have the '15551' SRO. While the crystalline structures with the\n'3661' SRO also exhibit the MRO very similar to that observed in the glass, the\nones with the '15551' SRO have very different atomic packing in the second and\nthird shells around the Tb centers from that of the Bergman-type MRO observed\nin the glassy phase."
    },
    {
        "anchor": "Theoretical investigation of half-metallicity in Co/Ni substituted AlN: Results of Co and Ni substituted AlN in the zinc blende phase are presented.\nFor spin up states the hybridized N-2p and Co/Ni-3d states form the valance\nbands with a bandgap around the Fermi level for both materials, while in the\ncase of the spin down states the hybridized states cross the Fermi level and\nhence show metallic nature. It is found that, Al0.75Co0.25N and Al0.75Ni0.25N\nare ferromagnetic materials with magnetic moments of 4 {\\mu}B and 3 {\\mu}B\nrespectively. The integer magnetic moments and the full spin polarization at\nthe Fermi level make these compounds half-metallic semiconductors. Furthermore\nit is also found that the interaction with the N-2p state splits the 5-fold\ndegenerate Co/Ni-3d states into t2g and eg states. The t2g states are located\nat higher energies than the eg states caused by the tetrahedral symmetry of\nthese compounds.",
        "positive": "Three-dimensional vortex structures and dynamics in hexagonal manganites: Hexagonal manganites REMnO3 (RE, rare earths) have attracted significant\nattention due to their potential applications as multiferroic materials and the\nintriguing physics associated with the topological defects. The two-dimensional\n(2D) and 3D domain and vortex structure evolution of REMnO3 is predicted using\nthe phase-field method based on a thermodynamic potential constructed from\nfirst-principles calculations. In 3D spaces, vortex lines show three types of\ntopological changes, i.e. shrinking, coalescence, and splitting, with the\nlatter two caused by the interaction and exchange of vortex loops. Compared to\nthe coarsening rate of the isotropic XY model, the six-fold degeneracy gives\nrise to negligible differences with the vortex-antivortex annihilation\ncontrolling the scaling dynamics, whereas the anisotropy of interfacial energy\nresults in a deviation. The temporal evolution of domain and vortex structures\nserves as a platform to fully explore the mesoscale mechanisms for the 0-D and\n1-D topological defects."
    },
    {
        "anchor": "Magnetoresistance of a semiconducting magnetic wire with domain wall: We investigate theoretically the influence of the spin-orbit interaction of\nRashba type on the magnetoresistance of a semiconducting ferromagnetic\nnanostructure with a laterally constrained domain wall. The domain wall is\nassumed sharp (on the scale of the Fermi wave length of the charge carriers).\nIt is shown that the magnetoresistance in such a case can be considerably\nlarge, which is in a qualitative agreement with recent experimental\nobservations. It is also shown that spin-orbit interaction may result in an\nincrease of the magnetoresistance. The role of localization corrections is also\nbriefly discussed.",
        "positive": "MatChat: A Large Language Model and Application Service Platform for\n  Materials Science: The prediction of chemical synthesis pathways plays a pivotal role in\nmaterials science research. Challenges, such as the complexity of synthesis\npathways and the lack of comprehensive datasets, currently hinder our ability\nto predict these chemical processes accurately. However, recent advancements in\ngenerative artificial intelligence (GAI), including automated text generation\nand question-answering systems, coupled with fine-tuning techniques, have\nfacilitated the deployment of large-scale AI models tailored to specific\ndomains. In this study, we harness the power of the LLaMA2-7B model and enhance\nit through a learning process that incorporates 13,878 pieces of structured\nmaterial knowledge data. This specialized AI model, named MatChat, focuses on\npredicting inorganic material synthesis pathways. MatChat exhibits remarkable\nproficiency in generating and reasoning with knowledge in materials science.\nAlthough MatChat requires further refinement to meet the diverse material\ndesign needs, this research undeniably highlights its impressive reasoning\ncapabilities and innovative potential in the field of materials science.\nMatChat is now accessible online and open for use, with both the model and its\napplication framework available as open source. This study establishes a robust\nfoundation for collaborative innovation in the integration of generative AI in\nmaterials science."
    },
    {
        "anchor": "Numerical Investigations of Strain-Gradient Plasticity with Reference to\n  Non-Homogeneous Deformations: In this work, a higher-order irrotational strain gradient plasticity theory\nis studied in the small strain regime. A detailed numerical study is based on\nthe problem of simple shear of a non-homogeneous block comprising an\nelastic-plastic material with a stiff? elastic inclusion. Combinations of\nmicro-hard and micro-free boundary conditions are used. The strengthening and\nhardening behavior is explored in relation to the dissipative and energetic\nlength scales. There is a strong dependence on length scale with the imposition\nof micro-hard boundary conditions. For micro-free conditions there is marked\ndependence on dissipative length scale of initial yield, though the differences\nare small in the post-yield regime. In the case of hardening behavior, the\nvariation with respect to energetic length scale is negligible. A further\nphenomenon studied numerically relates to the global nature of the yield\nfunction for the dissipative problem; this function is given as the least upper\nbound of a function of plastic strain increment, and cannot be determined\nanalytically. The accuracy of an upper-bound approximation to the yield\nfunction is explored, and found to be reasonably sharp in its prediction of\ninitial yield.",
        "positive": "Strengthening from dislocation restructuring and local climb at platelet\n  linear complexions in Al-Cu alloys: Stress-driven segregation at dislocations can lead to structural transitions\nbetween different linear complexion states. In this work, we examine how\nplatelet array linear complexions influence dislocation motion and quantify the\nassociated strengthening effect in Al-Cu alloys using atomistic simulations.\nThe presence of platelet complexions leads to faceting of the dislocations,\nwith nanoscale segments climbing upwards along the platelet growth direction,\nresulting in a complex non-planar configuration that restricts subsequent\ndislocation motion. Upon deformation, the leading partial dislocation must\nclimb down from the platelet complexions first, followed by a similar sequence\nat the trailing partial dislocation, in order to overcome the precipitates and\ncommence plastic slip. The dislocation depinning mechanism of linear\ncomplexions is strikingly different from traditional precipitation-strengthened\nalloys, where dislocations overcome obstacles by either shearing through or\nlooping around obstacles. The critical shear stress required to unpin\ndislocations from platelet complexions is found to be inversely proportional to\nprecipitate spacing, which includes not just the open space (as observed in\nOrowan bowing) but also the region along the platelet particle where climb\noccurs. Thus, platelet linear complexions provide a new way to modify\ndislocation structure directly and improve the mechanical properties of metal\nalloys."
    },
    {
        "anchor": "Shaping the Beam of Light in Nanometer Scales: A Yagi-Uda Nanoantenna in\n  Optical Domain: A Yagi-Uda-like optical nanoantenna concept using resonant core-shell\nplasmonic particles as its \"reflectors\" and \"directors\" is studied numerically.\nSuch particles when placed near an optical dipole source in a certain\narrangement may exhibit large induced dipole moments, resulting in shaping the\nfar-field radiation pattern, analogous to the far field of classical Yagi-Uda\nantennas in the microwave regime. Variation of the ratio of radii in concentric\ncore-shell nanostructure is used to tailor the phase of the polarizabilities of\nthe particles, and consequently the antenna's far-field pattern. The idea of a\nnanospectrum analyzer is also briefly proposed for molecular spectroscopy.",
        "positive": "Temperature dependent Raman study of phonons of different symmetries in\n  single crystal Bi2Se3: High quality single crystals of Bi2Se3 were grown using a modified Bridgman\ntechnique, the detailed study were carried out using Raman spectroscopy and\ncharacterized by Laue diffraction and high resolution transmission electron\nmicroscopy. Polarized Raman scattering measurements were also carried out, and\nboth the A1g and A2g phonon modes showed strong polarization effect, which is\nconsistent with the theoretical prediction. The temperature dependent study (in\nthe temperature range 83 K to 523 K of Raman active modes were reported and\nobserved to follow a systematic red shift. The frequency of these phonon modes\nare found to vary linearly with temperature and can be explained by first order\ntemperature co-efficient. The temperature co-efficient for A11g, E2g and A21g\nmodes were estimated to be -1.44*10-2, -1.94*10-2 and -1.95*10-2cm-1/K\nrespectively."
    },
    {
        "anchor": "Self-energy and lifetime of Shockley and image states on Cu(100) and\n  Cu(111): Beyond the GW approximation of many-body theory: We report many-body calculations of the self-energy and lifetime of Shockley\nand image states on the (100) and (111) surfaces of Cu that go beyond the $GW$\napproximation of many-body theory. The self-energy is computed in the framework\nof the GW\\Gamma approximation by including short-range exchange-correlation\n(XC) effects both in the screened interaction W (beyond the random-phase\napproximation) and in the expansion of the self-energy in terms of W (beyond\nthe GW approximation). Exchange-correlation effects are described within\ntime-dependent density-functional theory from the knowledge of an adiabatic\nnonlocal XC kernel that goes beyond the local-density approximation.",
        "positive": "Physisorption of molecular oxygen on single-wall carbon nanotube bundles\n  and graphite: We present a study on the kinetics of oxygen adsorption and desorption from\nsingle-wall carbon nanotube (SWNT) and highly oriented pyrolytic graphite\n(HOPG) samples. Thermal desorption spectra for SWNT samples show a broad\ndesorption feature peaked at 62 K which is shifted to significantly higher\ntemperature than the low-coverage desorption feature on HOPG. The low-coverage\nO2 binding energy on SWNT bundles, 18.5 kJ/mol, is 55% higher than that for\nadsorption on HOPG, 12.0 kJ/mol. In combination with molecular mechanics\ncalculations we show that the observed binding energies for both systems can be\nattributed to van der Waals interactions, i.e. physisorption. The experiments\nprovide no evidence for a more strongly bound chemisorbed species or for\ndissociative oxygen adsorption."
    },
    {
        "anchor": "In situ Imaging of Precipitate Formation in Additively Manufactured\n  Al-Alloys by Scanning X-ray Fluorescence: A new family of high-strength Al-alloys has recently been developed, tailored\nfor the powder bed fusion-laser beam process. In these alloys, Mn, Cr and Zr\nare incorporated in solid solution at amounts up to three times that of\nequilibrium in the as-printed state. Mn and Cr-enriched precipitates that form\nduring printing and heat treatment influence the material's mechanical\nproperties. In this study, direct imaging of these precipitates was\naccomplished through the utilisation of in situ synchrotron-based scanning\nX-ray fluorescence. During heat treatment, a selective accumulation of Cr and\nMn in two distinct types of precipitates at grain boundaries was observed.\nAdditionally, the microstructure at the melt-pool boundary, containing\nprecipitates found in the as-printed state, remains thermally stable during the\nheat treatment. The study demonstrates the significant value of employing\nhigh-sensitivity in-situ X-ray fluorescence microscopy in exploring the\nkinetics of sub-micrometre scale precipitation.",
        "positive": "Dielectric permittivity, conductivity and breakdown field of hexagonal\n  boron nitride: In view of the extensive use of hexagonal boron nitride (hBN) in 2D material\nelectronics, it becomes important to refine its dielectric characterization in\nterms of low-field permittivity and high-field strength and conductivity up to\nthe breakdown voltage. The present study aims at filling this gap using DC and\nRF transport in two Au-hBN-Au capacitor series of variable thickness in the\n10--100 nm range, made of large high-pressure, high-temperature (HPHT) crystals\nand a polymer derivative ceramics (PDC) crystals. We deduce an out-of-plane low\nfield dielectric constant $\\epsilon_\\parallel=3.4\\pm0.2$ consistent with the\ntheoretical prediction of Ohba et al., that narrows down the generally accepted\nwindow $\\epsilon_\\parallel=3$--$4$. The DC-current leakage at high-field is\nfound to obey the Frenkel-Pool law for thermally-activated trap-assisted\nelectron transport with a dynamic dielectric constant\n$\\epsilon_\\parallel\\simeq3.1$ and a trap energy $\\Phi_B\\simeq1.3\\;\\mathrm{eV}$,\nthat is comparable with standard technologically relevant dielectrics."
    },
    {
        "anchor": "Direct Visualization of Irreducible Ferrielectricity in Crystals: In solids, charge polarity can one-to-one correspond to spin polarity\nphenomenologically, e.g. ferroelectricity/ferromagnetism,\nantiferroelectricity/antiferromagnetism, and even\ndipole-vortex/magnetic-vortex, but ferrielectricity/ferrimagnetism kept telling\na disparate story in microscopic level. Since the definition of a charge dipole\ninvolves more than one ion, there may be multiple choices for a dipole unit,\nwhich makes most ferrielectric orders equivalent to ferroelectric ones, i.e.\nthis ferrielectricity is not necessary to be a real independent branch of\npolarity. In this work, by using the spherical aberration-corrected scanning\ntransmission electron microscope, we visualize a nontrivial ferrielectric\nstructural evolution in BaFe2Se3, in which the development of two polar\nsub-lattices is out-of-sync, for which we term it as irreducible\nferrielectricity. Such irreducible ferrielectricity leads to a non-monotonic\nbehavior for the temperature-dependent polarization, and even a compensation\npoint in the ordered state. Our finding unambiguously distinguishes\nferrielectrics from ferroelectrics in solids.",
        "positive": "Orbital order and ferrimagnetic properties of the new compound $Sr_8 Ca\n  Re_3 Cu_4 O_{24}$: By means of the LSDA+U method and the Green function method, we investigate\nthe electronic and magnetic properties of the new material of\nSr$_8$CaRe$_3$Cu$_4$O$_{24}$. Our LSDA+U calculation shows that this system is\nan insulator with a net magnetic moment of 1.01 $\\mu_{\\rm B}$/f.u., which is in\ngood agreement with the experiment. Magnetic moments are mainly located at Cu\natoms, and the magnetic moments of neighboring Cu sites align anti-parallel. It\nis the non-magnetic Re atoms that induce an orbital order of $d$ electrons of\nCu atoms, which is responsible for the strong exchange interaction and the high\nmagnetic transition temperature. Based on the LSDA+U results, we introduce an\neffective model for the spin degrees of freedom, and investigate the\nfinite-temperature properties by the Green function method. The obtained\nresults are consistent with the experimental results, indicating that the\nspin-alternating Heisenberg model is suitable for this compound."
    },
    {
        "anchor": "Anisotropic Behavior of Excitons in Single Crystal \u03b1-SnS: We investigate analytically the anisotropic dielectric properties of single\ncrystal {\\alpha}-SnS near the fundamental absorption edge by considering atomic\norbitals. Most striking is the excitonic feature in the armchair- (b-) axis\ndirection, which is particularly prominent at low temperatures. To determine\nthe origin of this anisotropy, we perform first-principles calculations using\nthe GW0 Bethe-Salpeter equation (BSE) including the electron-hole interaction.\nThe results show that the anisotropic dielectric characteristics are a direct\nresult of the natural anisotropy of p orbitals. In particular, this dominant\nexcitonic feature originates from the py orbital at the saddle point in the\n{\\Gamma}-Y region.",
        "positive": "Contact conductance governs metallicity in conducting metal oxide\n  nanocrystal films: In bulk semiconductor materials, the insulator-metal transition (IMT) is\ngoverned by the concentration of conduction electrons. Meanwhile, even when\nfabricated from metallic building blocks, nanocrystal films are often\ninsulating with inter-nanocrystal contacts acting as electron transport\nbottlenecks. Using a library of transparent conducting tin-doped indium oxide\nnanocrystal films with varied electron concentration, size, and contact area,\nwe test candidate criteria for the IMT and establish a phase diagram for\nelectron transport behavior. From variable temperature conductivity\nmeasurements, we learn that both the IMT and a subsequent crossover to\nconventional metallic behavior near room temperature are governed by the\nconductance of the inter-nanocrystal contacts. To cross the IMT,\ninter-nanocrystal coupling must be sufficient to overcome the charging energy\nof a nanocrystal, while conventional metallic behavior requires contact\nconductance to reach the conductance of a nanocrystal. This understanding can\nenable the design and fabrication of metallic conducting materials from\nnanocrystal building blocks."
    },
    {
        "anchor": "Diamond Surface Functionalization via Visible Light-Driven C-H\n  Activation for Nanoscale Quantum Sensing: Nitrogen-vacancy centers in diamond are a promising platform for nanoscale\nnuclear magnetic resonance sensing. Despite significant progress towards using\nNV centers to detect and localize nuclear spins down to the single spin level,\nNV-based spectroscopy of individual, intact, arbitrary target molecules remains\nelusive. NV molecular sensing requires that target molecules are immobilized\nwithin a few nanometers of NV centers with long spin coherence time. The inert\nnature of diamond typically requires harsh functionalization techniques such as\nthermal annealing or plasma processing, limiting the scope of functional groups\nthat can be attached to the surface. Solution-phase chemical methods can be\nmore readily generalized to install diverse functional groups, but they have\nnot been widely explored for single-crystal diamond surfaces. Moreover,\nrealizing shallow NV centers with long spin coherence times requires highly\nordered single-crystal surfaces, and solution-phase functionalization has not\nyet been shown to be compatible with such demanding conditions. In this work,\nwe report a versatile strategy to directly functionalize C-H bonds on\nsingle-crystal diamond surfaces under ambient conditions using visible light.\nThis functionalization method is compatible with charge stable NV centers\nwithin 10 nm of the surface with spin coherence times comparable to the state\nof the art. As a proof of principle, we use shallow ensembles of NV centers to\ndetect nuclear spins from functional groups attached to the surface. Our\napproach to surface functionalization based on visible light-driven C-H bond\nactivation opens the door to deploying NV centers as a broad tool for chemical\nsensing and single-molecule spectroscopy.",
        "positive": "Large nonlinear absorption and refraction coefficients of carbon\n  nanotubes estimated from femtosecond Z-scan measurements: Nonlinear transmission of 80 and 140 femtosecond pulsed light with $0.79 \\mu\nm$ wavelength through single walled carbon nanotubes suspended in water\ncontaining sodium dodecyl sulphate is studied. Pulse-width independent\nsaturation absorption and negative cubic nonlinearity are observed,\nrespectively, in open and closed aperture Z-scan experiments. The theoretical\nexpressions derived to analyze the z-dependent transmission in the saturable\nlimit require two photon absorption coefficient $\\beta_0\\sim$ $1.4 cm/MW$ and a\nnonlinear index $\\gamma \\sim -5.5 \\times10^{-11} cm^2/W$ to fit the data."
    },
    {
        "anchor": "Molecular Dynamics Simulations of Chemically Disordered Ferroelectric\n  (Ba,Sr)TiO$_3$ with a Semi-Empirical Effective Hamiltonian: We present a semi-empirical effective Hamiltonian to capture effects of\ndisorder associated with Ba and Sr cations occupying $A$ sites in\n(Ba$_{x}$Sr$_{1-x}$)TiO$_3$ on its ferroelectric phase transition. Averaging\nbetween the parameters of first-principles effective Hamiltonians of end\nmembers BaTiO$_3$ and SrTiO$_3$, we include a term with an empirical parameter\nto capture the local polarization and strains arising from the difference\nbetween ionic radii of Ba and Sr. Using mixed-space molecular dynamics of the\neffective Hamiltonian, we determine $T$-dependent ferroelectric phase\ntransitions in (Ba$_{x}$Sr$_{1-x}$)TiO$_3$ which are in good agreement with\nexperiment. Our scheme of determination of semi-empirical parameters in\neffective Hamiltonian should be applicable to other perovskite-type\nferroelectric solid solutions.",
        "positive": "High-performance Thermal Interface Material Based on Few-layer Graphene\n  Composite: We developed high-performance thermal interface materials (TIMs) based on\nfew-layer graphene (FLG) composite, where FLG was prepared by the interlayer\ncatalytic exfoliation (ICE) method. We experimentally demonstrated feasibility\nof FLG composites as TIMs by investigating their thermal and mechanical\nproperties, and reliability. We measured the thermal interface resistance\n($R_{int}$) between FLG composite TIMs (FLGTs) and copper and to be 3.2$\\pm$1.7\nand 4.3$\\pm$1.4 $mm^2$K/W for 5 vol.% and 10 vol.% FLGTs at 330 K,\nrespectively, comparable to or even lower than that of many commercial TIMs. In\naddition, the thermal conductivity ($\\kappa_{TIM}$) of FLGTs is increased by an\nenhancement factor ($\\beta$) of ~17 as the FLG concentration increases from 0\nto 10 vol.%. We also characterized Vickers hardness and glass transition\ntemperature ($T_g$) of our FLGTs. We find that our FLGTs are thermally and\nmechanically reliable within practical operating temperature and pressure\nranges."
    },
    {
        "anchor": "Structural phase transitions and fundamental band gaps of Mg(x)Zn(1-x)O\n  alloys from first principles: The structural phase transitions and the fundamental band gaps of\nMg(x)Zn(1-x)O alloys are investigated by detailed first-principles calculations\nin the entire range of Mg concentrations x, applying a multiple-scattering\ntheoretical approach (Korringa-Kohn-Rostoker method). Disordered alloys are\ntreated within the coherent potential approximation (CPA). The calculations for\nvarious crystal phases have given rise to a phase diagram in good agreement\nwith experiments and other theoretical approaches. The phase transition from\nthe wurtzite to the rock-salt structure is predicted at the Mg concentration of\nx = 0.33, which is close to the experimental value of 0.33 - 0.40. The size of\nthe fundamental band gap, typically underestimated by the local density\napproximation, is considerably improved by the self-interaction correction. The\nincrease of the gap upon alloying ZnO with Mg corroborates experimental trends.\nOur findings are relevant for applications in optical, electrical, and in\nparticular in magnetoelectric devices.",
        "positive": "Repulsive and attractive Casimir interactions in liquids: The Casimir interactions in the solid-liquid-solid systems as a function of\nseparation distance have been studied by the Lifshitz theory. The dielectric\npermittivity functions for a wide range of materials are described by Drude,\nDrude-Lorentz and oscillator models. We find that the Casimir forces between\ngold and silica or MgO materials are both the repulsive and attractive. We also\nfind the stable forms for the systems. Our studies would provide a good\nguidance for the future experimental studies on the dispersion interactions."
    },
    {
        "anchor": "Robust negative longitudinal magnetoresistance and spin-orbit torque in\n  sputtered Pt3Sn topological semimetal: Contrary to topological insulators, topological semimetals possess a\nnontrivial chiral anomaly that leads to negative magnetoresistance and are\nhosts to both conductive bulk states and topological surface states with\nintriguing transport properties for spintronics. Here, we fabricate\nhighly-ordered metallic Pt3Sn and Pt3SnxFe1-x thin films via sputtering\ntechnology. Systematic angular dependence (both in-plane and out-of-plane)\nstudy of magnetoresistance presents surprisingly robust quadratic and linear\nnegative longitudinal magnetoresistance features for Pt3Sn and Pt3SnxFe1-x,\nrespectively. We attribute the anomalous negative longitudinal\nmagnetoresistance to the type-II Dirac semimetal phase (pristine Pt3Sn) and/or\nthe formation of tunable Weyl semimetal phases through symmetry breaking\nprocesses, such as magnetic-atom doping, as confirmed by first-principles\ncalculations. Furthermore, Pt3Sn and Pt3SnxFe1-x show the promising performance\nfor facilitating the development of advanced spin-orbit torque devices. These\nresults extend our understanding of chiral anomaly of topological semimetals\nand can pave the way for exploring novel topological materials for spintronic\ndevices.",
        "positive": "Synthesis of infinite-layer nickelates and influence of the\n  capping-layer on magnetotransport: The recent discovery of a zero-resistance state in nickel-based compounds has\ngenerated a re-excitement about the long-standing problem in condensed matter\nof high-critical-temperature superconductivity, in light of the analogies\nbetween infinite-layer nickelates and cuprates. However, despite some formal\nvalence and crystal symmetry analogies, the electronic properties of\ninfinite-layer nickelates are remarkably original accounting, among other\nproperties, of a unique Nd5d-Ni3d hybridization. This designates infinite-layer\nnickelates as a new class of oxide superconductors which should be considered\non their own. Here we report about Nd1-xSrxNiO2 (x = 0, 0.05 and 0.2) thin\nfilms synthesized with and without a SrTiO3 capping-layer, showing very smooth\nand step-terraced surface morphologies. Angle-dependent anisotropic\nmagnetoresistance measurements performed with a magnetic field rotating\nin-plane or out-of-plane with respect to the sample surface, rendered important\ninformation about the magnetic properties of undoped SrTiO3-capped and uncapped\nsamples. The results point at a key role of the capping-layer in controlling\nthe magnitude and the anisotropy of the anisotropic magnetoresistance\nproperties. We discuss this control in terms of a combined effect between the\nNd-Ni hybridization and an intra-atomic exchange coupling between the Nd-4f and\nNd-5d states, the latter essentially contributing to the (magneto)transport.\nFurther studies foresee the influence of the capping layer on infinite-layer\nnickelates with no magnetic rare-earth."
    },
    {
        "anchor": "Low thermal conductivity of iron-silicon alloys at Earth core conditions\n  with implications for the geodynamo: Earth core is composed of iron (Fe) alloyed with light elements, e.g.,\nsilicon (Si). Its thermal conductivity critically affects Earth thermal\nstructure, evolution, and dynamics, as it controls the magnitude of thermal and\ncompositional sources required to sustain a geodynamo over Earth history. Here\nwe directly measured thermal conductivities of solid Fe and Fe-Si alloys up to\n144 GPa and 3300 K. 15 at% Si alloyed in Fe substantially reduces its\nconductivity by about 2 folds at 132 GPa and 3000 K. An outer core with 15 at%\nSi would have a conductivity of about 20 W m-1 K-1, lower than pure Fe at\nsimilar pressure-temperature conditions. This suggests a lower minimum heat\nflow, around 3 TW, across the core-mantle boundary than previously expected,\nand thus less thermal energy needed to operate the geodynamo. Our results\nprovide key constraints on inner core age that could be older than two\nbillion-years.",
        "positive": "D\u00e9mixtion et s\u00e9gr\u00e9gation superficielle dans les alliages\n  fer-chrome: Ferritic steels possibly strengthened by oxide dispersion are candidates as\nstructural materials for generation IV and fusion nuclear reactors. Their use\nis limited by incomplete knowledge of the iron-chromium phase diagram at low\ntemperatures and of the phenomena inducing preferential segregation of one\nelement at grain boundaries or at surfaces. In this context, this work\ncontributes to the multi-scale study of the model iron-chromium alloy and their\nfree surfaces by numerical simulations. This study begins with ab initio\ncalculations of properties related to the mixture of atoms of iron and\nchromium. We highlight complex dependency of the magnetic moments of the\nchromium atoms on their local chemical environment. Surface properties are also\nproving sensitive to magnetism. This is the case of impurity segregation of\nchromium in iron and of their interactions near the surface. In a second step,\nwe construct a simple energy model for high numerical efficiency. It is based\non pair interactions on a rigid lattice to which are given local chemical\nenvironment and temperature dependencies. With this model, we reproduce the ab\ninitio results at zero temperature and experimental results at high\ntemperature. We also deduce the solubility limits at all intermediate\ntemperatures with mean field approximations that we compare to Monte Carlo\nsimulations. The last step of our work is to introduce free surfaces in our\nmodel. We then study the effect of ab initio calculated bulk and surface\nproperties on surface segregation. Finally, we calculate segregation isotherms.\nWe therefore propose an evolution model of surface composition of iron-chromium\nalloys as a function of bulk composition."
    },
    {
        "anchor": "Hydrogen adatoms on graphene: the role of hybridization and lattice\n  distortion: Hydrogen adatoms on graphene are investigated using DFT and analytical\napproaches. We demonstrate that the level of lattice deformation due to the\nhydrogen adsorption does not substantially change the coupling between the\ngraphene $p_{z}$ orbitals. The hybridization primarily takes place between the\nadsorbate's s orbital and the graphene $p_{z}$ orbitals. We also show that the\nimpurity interaction with the graphene atoms is limited to only a few nearest\nneighbors, allowing us to construct a compact TB model for the\nimpurity-graphene system with an arbitrary impurity distribution. The\ncomplexity of our model scales with the number of impurities, not their\nseparation, making it especially useful in the study of low impurity\nconcentrations.",
        "positive": "Near-edge x-ray absorption fine structure investigation of graphene: We report the near-edge x-ray absorption fine structure (NEXAFS) spectrum of\na single layer of graphite (graphene) obtained by micromechanical cleavage of\nHighly Ordered Pyrolytic Graphite (HOPG) on a SiO2 substrate. We utilized a\nPhotoEmission Electron Microscope (PEEM) to separately study single- double-\nand few-layers graphene (FLG) samples. In single-layer graphene we observe a\nsplitting of the pi* resonance and a clear signature of the predicted\ninterlayer state. The NEXAFS data illustrate the rapid evolution of the\nelectronic structure with the increased number of layers."
    },
    {
        "anchor": "nmfMapping: a cloud-based web application for non-negative matrix\n  factorization of powder diffraction and pair distribution function datasets: A cloud-hosted web-based software application, nmfMapping, for carrying out a\nnonnegative matrix factorization of a set of powder diffraction or atomic pair\ndistribution function datasets is described. This app allows structure\nscientists to rapidly find trends in sets of related data such as from in situ\nand operando diffraction experiments. The application is easy to use and does\nnot require any programming expertise. It is available at the pdfitc.org\nwebsite.",
        "positive": "Ab initio simulations of hydrogen-bonded ferroelectrics: collective\n  tunneling and the origin of geometrical isotope effects: Ab initio simulations that account for nuclear quantum effects have been used\nto examine the order-disorder transition in squaric acid, a prototypical\nH-bonded antiferroelectric crystal. Our simulations reproduce the >100 K\ndifference in transition temperature observed upon deuteration as well as the\nstrong geometrical isotope effect observed on intermolecular separations within\nthe crystal. We find that collective transfer of protons along the H-bonding\nchains - facilitated by quantum mechanical tunneling - is critical to the\norder-disorder transition and the geometrical isotope effect. This sheds light\non the origin of isotope effects and the importance of tunneling in squaric\nacid which likely extends to other H-bonded ferroelectrics."
    },
    {
        "anchor": "Large Fermi Arcs in Unconventional Weyl Semimetal RhSi: The theoretical proposal of chiral fermions in topological semimetals has led\nto a significant effort towards their experimental realization. In particular,\nthe Fermi surfaces of chiral semimetals carry quantized Chern numbers, making\nthem an attractive platform for the observation of exotic transport and optical\nphenomena. While the simplest example of a chiral fermion in condensed matter\nis a conventional $|C|=1$ Weyl fermion, recent theoretical works have proposed\na number of unconventional chiral fermions beyond the Standard Model which are\nprotected by unique combinations of topology and crystalline symmetries.\nHowever, materials candidates for experimentally probing the transport and\nresponse signatures of these unconventional fermions have thus far remained\nelusive. In this paper, we propose the RhSi family in space group (SG) $\\#$198\nas the ideal platform for the experimental examination of unconventional chiral\nfermions. We find that RhSi is a filling-enforced semimetal that features near\nits Fermi surface a chiral double six-fold-degenerate spin-1 Weyl node at $R$\nand a previously uncharacterized four-fold-degenerate chiral fermion at\n$\\Gamma$. Each unconventional fermion displays Chern number $\\pm4$ at the Fermi\nlevel. We also show that RhSi displays the largest possible momentum separation\nof compensative chiral fermions, the largest proposed topologically nontrivial\nenergy window, and the longest possible Fermi arcs on its surface. We conclude\nby proposing signatures of an exotic bulk photogalvanic response in RhSi.",
        "positive": "Dislocations and Grain Boundaries in Two-Dimensional Boron Nitride: A new dislocation structure-square-octagon pair (4|8) is discovered in\ntwo-dimensional boron nitride (h-BN), via first-principles calculations. It has\nlower energy than corresponding pentagon-heptagon pairs (5|7), which contain\nunfavorable homo-elemental bonds. Based on the structures of dislocations,\ngrain boundaries (GB) in BN are investigated. Depending on the tilt angle of\ngrains, GB can be either polar (B-rich or N-rich), constituted by 5|7s, or\nun-polar, composed of 4|8s. The polar GBs carry net charges, positive at B-rich\nand negative at N-rich ones. In contrast to GBs in graphene which generally\nimpede the electronic transport, polar GBs have smaller bandgap compared to\nperfect BN, which may suggest interesting electronic and optic applications."
    },
    {
        "anchor": "Role of Exchange in Density Functional Theory for Weakly-Interacting\n  Systems: Quantum Monte Carlo Analysis of Electron Density and Interaction\n  Energy: We analyze the density functional theory (DFT) description of weak\ninteractions by employing diffusion and reptation quantum Monte Carlo (QMC)\ncalculations, for a set of benzene-molecule complexes. While the binding\nenergies depend significantly on the exchange correlation approximation\nemployed for DFT calculations, QMC calculations show that the electron density\nis accurately described within DFT, including the quantitative features in the\nreduced density gradient. We elucidate how the enhancement of the exchange\nenergy density at a large reduced density gradient plays a critical role in\nobtaining accurate DFT description of weakly-interacting systems.",
        "positive": "Selective oxidation-induced strengthening of Zr/Nb nanoscale multilayers: The paper presents a new approach, based on controlled oxidation of nanoscale\nmetallic multilayers, to produce strong and hard oxide/metal nanocomposite\ncoatings with high strength and good thermal stability. The approach is\ndemonstrated by performing long term annealing on sputtered Zr/Nb nanoscale\nmetallic multilayers and investigating the evolution of their microstructure\nand mechanical properties by combining analytical transmission electron\nmicroscopy, nano-mechanical tests and finite element models. As-deposited\nmultilayers were annealed at 350 C in air for times ranging between 1 - 336\nhours. The elastic modulus increased by approx. 20% and the hardness by approx.\n42% after 15 hours of annealing. Longer annealing times did not lead to changes\nin hardness, although the elastic modulus increased up to 35% after 336 hrs.\nThe hcp Zr layers were rapidly transformed into monoclinic ZrO2 (in the first\n15 hours), while the Nb layers were progressively oxidised, from top surface\ndown towards the substrate, to form an amorphous oxide phase at a much lower\nrate. The sequential oxidation of Zr and Nb layers was key for the oxidation to\ntake place without rupture of the multi-layered structure and without coating\nspallation, as the plastic deformation of the metallic Nb layers allowed for\nthe partial relieve of the residual stresses developed as a result of the\nvolumetric expansion of the Zr layers upon oxidation. Moreover, the development\nof residual stresses induced further changes in mechanical properties in\nrelation to the annealing time, as revealed by finite element simulations."
    },
    {
        "anchor": "Micromagnetics of shape anisotropy based permanent magnets: In the search for rare-earth free permanent magnets, various ideas related to\nshape anisotropy are being pursued. In this work we assess the limits of shape\ncontributions to the reversal stability using micromagnetic simulations. In a\nfirst series of tests we altered the aspect ratio of single phase prolate\nspheroids from 1 to 16. Starting with a sphere of radius $4.3$ times the\nexchange length $ L_{\\mathrm{ex}}$ we kept the total magnetic volume constant\nas the aspect ratio was modified. For a ferromagnet with zero\nmagnetocrystalline anisotropy the maximum coercive field reached up to $0.5$\ntimes the magnetization $M_{\\mathrm{s}}$. Therefore, in materials with moderate\nuniaxial magnetocrystalline anisotropy, the addition of shape anisotropy could\neven double the coercive field. Interestingly due to non-uniform magnetization\nreversal there is no significant increase of the coercive field for an aspect\nratio greater than 5. A similar limit of the maximum aspect ratio was observed\nin cylinders. The coercive field depends on the wire diameter. By decreasing\nthe wire diameter from $8.7 L_{\\mathrm{ex}}$ to $2.2 L_{\\mathrm{ex}}$ the\ncoercive field increased by 40%. In the cylinders nucleation of a reversed\ndomain starts at the corners at the end. Smoothing the edges can improve the\ncoercive field by about 10%.\n  In further simulations we compacted soft magnetic cylinders into a bulk-like\narrangement. Misalignment and magnetostatic interactions cause a spread of $0.1\nM_{\\mathrm{s}}$ in the switching fields of the rods. Comparing the volume\naveraged hysteresis loops computed for isolated rods and the hysteresis loop\ncomputed for interacting rods, we conclude that magnetostatic interactions\nreduce the coercive field by up to 20%.",
        "positive": "First-principles study of native point defects in topological insulator\n  Bi$_2$Se$_3$: The \\emph{p}-type Bi$_{2}$Se$_{3}$ is much desirable as a promising\nthermoelectric material and topological insulator, while the naturally grown\nBi$_{2}$Se$_{3}$ is always \\emph{n}-type doped by native point defects. Here we\nuse first-principles calculations to identify the origin of the \\emph{n}-type\ntendency in bulk Bi$_{2}$Se$_{3}$: The Se vacancies (V$_\\text{Se1}$ and\nV$_\\text{Se2}$) and Se$_{\\text{Bi}}$ antisite dominate the donorlike doping\nwith low formation energy, while the predisposed Bi$_{\\text{Se1}}$ defect\nresults in the pair of V$_\\text{Se1}$ and Bi interstitial, which is also a\ndonor rather than an acceptor. Moreover, for Bi$_{2}$Se$_{3}$(111) surface, we\nfind that the band structures modulated by the defects explicitly account for\nthe existing experimental observations of \\emph{n}-type preference."
    },
    {
        "anchor": "Solution to the hole-doping problem and tunable quantum Hall effect in\n  Bi$_{2}$Se$_{3}$ thin films: Bi$_{2}$Se$_{3}$, one of the most widely studied topological insulators\n(TIs), is naturally electron-doped due to n-type native defects. However, many\nyears of efforts to achieve p-type Bi$_{2}$Se$_{3}$ thin films have failed so\nfar. Here, we provide a solution to this long-standing problem, showing that\nthe main culprit has been the high density of interfacial defects. By\nsuppressing these defects through an interfacial engineering scheme, we have\nsuccessfully implemented p-type Bi$_{2}$Se$_{3}$ thin films down to the\nthinnest topological regime. On this platform, we present the first tunable\nquantum Hall effect (QHE) study in Bi$_{2}$Se$_{3}$ thin films, and reveal not\nonly significantly asymmetric QHE signatures across the Dirac point but also\nthe presence of competing anomalous states near the zeroth Landau level. The\navailability of doping tunable Bi$_{2}$Se$_{3}$ thin films will now make it\npossible to implement various topological quantum devices, previously\ninaccessible.",
        "positive": "Kinetic Magnetism and Orbital Order in Iron Telluride: Iron telluride (FeTe), a relative of the iron based high temperature\nsuperconductors, displays unusual magnetic order and structural transitions.\nHere we explore the idea that strong correlations may play an important role in\nthese materials. We argue that the unusual orders observed in FeTe can be\nunderstood from a picture of correlated local moments with orbital degeneracy,\ncoupled to a small density of itinerant electrons. A component of the\nstructural transition is attributed to orbital, rather than magnetic ordering,\nintroducing a strongly anisotropic character to the system along the diagonal\ndirections of the iron lattice. Double exchange interactions couple the\ndiagonal chains leading to the observed ordering wavevector. The incommensurate\norder in samples with excess iron arises from electron doping in this scenario.\nThe strong anisotropy of physical properties in the ordered phase should be\ndetectable by transport in single domains. Predictions for ARPES, inelastic\nneutron scattering and hole/electron doping studies are also made."
    },
    {
        "anchor": "Boosting spin-orbit torque efficiency in spin-current\n  generator/magnet/oxide superlattices: Efficient manipulation of magnetic materials is essential for spintronics. In\nspin-current generator/magnet bilayers, the efficiency of spin-orbit torques\nper magnetic layer thickness scales inversely with the magnetic layer\nthickness, leading to considerable power increase in applications with large\nmagnetic layer thickness. Here, we develop a 3D spin-orbit material scheme in\nwhich the spin torque efficiency can be remarkably boosted up by stacking\n[spin-current generator/magnet/oxide]n superlattices, with the oxide layers\nbreaking the inversion symmetry. In contrast, the spin torque diminishes in\n[spin-current generator/magnet]n superlattices lacking inversion symmetry\nbreaking. These results advances the understanding of spin-orbit torques in\nmagnetic multilayers and establishes spin-current generator/magnet/oxide\nsuperlattices as advantageous bricks for development of high energy-efficiency,\nhigh-endurance, and high-density spintronic memory and computing.",
        "positive": "Symmetry protection and giant Fermi arcs from multifold fermions in\n  binary, ternary, and quaternary compounds: Higher-fold chiral fermions that go beyond two-fold Weyl fermions have\nrecently been reported in crystalline systems. Here, we focus on such\nexcitations in several binary, ternary and quaternary alloys/compounds with\nCoGe, BiSbPt and KMgBO3 as the representative examples that belong to the\ncrystal space group (SG) 198. We found distinct three-fold, four-fold and\nsix-fold chiral fermions in the bulk via Density Functional computations. We\nprovide general symmetry arguments for the protection of these degeneracies\nwith special emphasis on the four-fold fermions. Our surface spectra\nsimulations show that the size of Fermi arcs resulting from these chiral\nfermions are large, robust and untouched from the bulk states due to the near\nabsence of trivial bulk Fermi pockets. All these features make these systems --\nespecially CoGe and KMgBO3 -- promising topological semimetal candidates to\nrealize higher-fold fermions in future photo-emission and transport\nexperiments."
    },
    {
        "anchor": "Extended Pattern Recognition Scheme for Self-learning Kinetic Monte\n  Carlo (SLKMC-II) Simulations: We report the development of a pattern-recognition scheme that takes into\naccount both fcc and hcp adsorption sites in performing self-learning kinetic\nMonte Carlo (SLKMC-II) simulations on the fcc(111) surface. In this scheme, the\nlocal environment of every under-coordinated atom in an island is uniquely\nidentified by grouping fcc sites, hcp sites and top-layer substrate atoms\naround it into hexagonal rings. As the simulation progresses, all possible\nprocesses including those like shearing, reptation and concerted gliding, which\nmay involve fcc-fcc, hcp-hcp and fcc-hcp moves are automatically found, and\ntheir energetics calculated on the fly. In this article we present the results\nof applying this new pattern-recognition scheme to the self-diffusion of 9-atom\nislands (M9) on M(111), where M = Cu, Ag or Ni.",
        "positive": "Investigation of phonon behavior in Pr2NiMnO6 by micro-Raman\n  spectroscopy: The temperature dependence of phonon excitations and the presence of spin\nphonon coupling in polycrystalline Pr2NiMnO6 samples were studied using\nmicro-Raman spectroscopy and magnetometry. Magnetic properties show a single\nferromagnetic-to-paramagnetic transition at 228 K and a saturation\nmagnetization close to 4.95 \\muB/f.u.. Three distinct Raman modes at 657, 642,\nand 511 cm-1 are observed. The phonon excitations show a clear hardening due to\nanharmonicity from 300 K down to 10 K. Further, temperature dependence of the\n657 cm-1 mode shows only a small softening. This reflects the presence of a\nrelatively weak spin-phonon coupling in Pr2NiMnO6 contrary to other double\nperovskites previously studied."
    },
    {
        "anchor": "Highly strained Ge micro-blocks bonded on Si platform for Mid-Infrared\n  photonic applications: Adding sufficient tensile strain to Ge can turn the material to a direct\nbandgap group IV semiconductor emitting in the mid-infrared wavelength range.\nHowever, highly strained-Ge cannot be directly grown on Si due to its large\nlattice mismatch. In this work, we have developed a process based on Ge\nmicro-bridge strain redistribution intentionally landed to the Si substrate.\nTraction arms can be then partially etched to keep only localized strained-Ge\nmicro-blocks. Large tunable uniaxial stresses up to 4.2% strain were\ndemonstrated bonded on Si. Our approach allows to envision integrated\nstrained-Ge on Si platform for mid-infrared integrated optics.",
        "positive": "Raman Topography and Strain Uniformity of Large-Area Epitaxial Graphene: We report results from two-dimensional Raman spectroscopy studies of\nlarge-area epitaxial graphene grown on SiC. Our work reveals unexpectedly large\nvariation in Raman peak position across the sample resulting from inhomogeneity\nin the strain of the graphene film, which we show to be correlated with\nphysical topography by coupling Raman spectroscopy with atomic force\nmicroscopy. We report that essentially strain free graphene is possible even\nfor epitaxial graphene."
    },
    {
        "anchor": "Three-dimensional Atomic Mapping of Ligands on Nanoparticles: Capping ligands are crucial to synthesize colloidal nanoparticles with novel\nfunctional properties. However, the interaction between capping ligands and\ntheir interaction with the crystallographic surfaces of nanoparticles during\ncolloidal synthesis remains a great mystery, due to the lack of direct imaging\ntechniques. In this study, atom probe tomography was adopted to investigate the\nthree-dimensional atomic-scale distribution of two of the most common types of\nthese ligands, cetrimonium and halide (Br and Cl) ions, on Pd nanoparticles.\nThe results, validated using the density functional theory, demonstrated that\nthe Br anions adsorbed on the nanoparticle surfaces promote the adsorption of\nthe cetrimonium cations through electrostatic interactions, stabilizing the Pd\n{111} facets.",
        "positive": "A latent heat method to detect melting and freezing of metals at megabar\n  pressures: The high-pressure melting curves of metals provide simple and useful tests\nfor theories of melting, as well as important constraints for the modeling of\nplanetary interiors. Here, we present an experimental technique that reveals\nthe latent heat of fusion of a metal sample compressed inside a diamond anvil\ncell. The technique combines microsecond-timescale pulsed electrical heating\nwith an internally-heated diamond anvil cell for the first time. Further, we\nuse the technique to measure the melting curve of platinum to the highest\npressure measured to date. Melting temperature increases from $\\sim 3000$ K at\n34 GPa to $\\sim 4500$ K at 107 GPa, thermodynamic conditions that are between\nthe steep and shallow experimental melting curves reported previously. The\nmelting curve is a linear function of compression over the 0 to 20% range of\ncompression studied here, allowing a good fit to the Kraut-Kennedy empirical\nmodel with fit parameter $C=6.0$."
    },
    {
        "anchor": "Thermal response of photovoltaic cell to laser beam irradiation: This paper firstly presents the concept of using dual laser beam to irradiate\nthe photovoltaic cell, so as to investigate the temperature dependency of the\nefficiency of long distance energy transmission. Next, the model on the\nmultiple reflection and absorption of any monochromatic light in multilayer\nstructure has been established, and the heat generation in photovoltaic cell\nhas been interpreted in this work. Then, the finite element model has been set\nup to calculate the temperature of photovoltaic cell subjected to laser\nirradiation. Finally, the effect of temperature elevation on the efficiency and\nreliability of photovoltaic cell has been discussed to provide theoretical\nreferences for designing the light-electricity conversion system.",
        "positive": "Impact of Surface and Pore Characteristics on Fatigue Life of Laser\n  Powder Bed Fusion Ti-6Al-4V Alloy Described by Neural Network Models: In this study, the effects of surface roughness and pore characteristics on\nfatigue lives of laser powder bed fusion (LPBF) Ti-6Al-4V parts were\ninvestigated. The 197 fatigue bars were printed using the same laser power but\nwith varied scanning speeds. These actions led to variations in the geometries\nof microscale pores, and such variations were characterized using\nmicro-computed tomography. To generate differences in surface roughness in\nfatigue bars, half of the samples were grit-blasted and the other half\nmachined. Fatigue behaviors were analyzed with respect to surface roughness and\nstatistics of the pores. For the grit-blasted samples, the contour laser scan\nin the LPBF strategy led to a pore-depletion zone isolating surface and\ninternal pores with different features. For the machined samples, where surface\npores resemble internal pores, the fatigue life was highly correlated with the\naverage pore size and projected pore area in the plane perpendicular to the\nstress direction. Finally, a machine learning model using a drop-out neural\nnetwork (DONN) was employed to establish a link between surface and pore\nfeatures to the fatigue data (logN), and good prediction accuracy was\ndemonstrated. Besides predicting fatigue lives, the DONN can also estimate the\nprediction uncertainty."
    },
    {
        "anchor": "Evaluation of the hydrogen solubility and diffusivity in\n  proton-conducting oxides by converting the PSL values of a tritium imaging\n  plate: Proton-conducting oxides have potential applications in hydrogen sensors,\nhydrogen pumps, and other electrochemical devices including the tritium\npurification and recovery systems of nuclear fusion reactors. Although the\ndistribution of hydrogen (H) in such oxide materials is an important aspect,\nits precise measurement is difficult. In the present study, the hydrogen\nsolubility and diffusivity behavior of BaZr0.9Y0.1O2.95 (BZY),\nBaZr0.955Y0.03Co0.015O2.97 (BZYC), and CaZr0.9In0.1O2.95 (CZI) were studied\nusing tritiated heavy water vapor i.e., DTO (~2 kPa, tritium (T) = 0.1%) by\nconverting the photostimulated luminescence (PSL) values of the imaging plate\n(IP). The samples were exposed to DTO vapor at 673 K for 2 h or at 873 K for 1\nh. The disc-shaped oxide specimens (diameter ~7.5 mm; thickness ~2.3 mm;\ntheoretical density (TD) > 98 %) were prepared by conventional powder\nmetallurgy. The IP images of the specimen surfaces of all the three materials\nT-exposed revealed that BZY showed the most uniform T distribution with the\nhighest tritium activity. The cross-sectional T concentration profiles of the\ncut specimens showed that T diffused deeper into BZY and BZYC than into CZI.\nThe hydrogen solubility and diffusivity in the CZI specimen were lower than\nthat in the BZY and BZYC specimens. This suggested that barium zirconates were\nmore favorable proton conductors than calcium zirconates.",
        "positive": "Trial of a search for a face-centered-cubic high-entropy alloy\n  superconductor: With the aim of the discovery of face-centered-cubic (fcc) high-entropy alloy\n(HEA) superconductor, we have carried out materials research on Nb or\nPb-containing multi-component alloys. Although the X-ray diffraction (XRD)\npatterns of some Nb-containing samples exhibited the dominant fcc phases, no\nsuperconducting signals were observed down to 3 K. Examination with an energy\ndispersive X-ray spectrometer revealed that all samples were multi-phase, but\nthe existence of several new Nb-containing HEA phases was found in them. It was\nconfirmed that the synthesis of Pb-containing an HEA or quaternary alloy would\nbe difficult, probably due to the large differences in the crystal structure\nand atomic radius among constituent elements, low reaction temperature and the\nlack of a rapid cooling process in the synthesis. Despite the negative results\nin this research, some hints for an improved strategy for the search for an fcc\nHEA superconductor are provided. Moreover, our results are useful as\nfundamental data for future HEA predictions or for studies of phase relations\nin Nb or Pb-containing multi-component alloys based on the CALPHAD (calculation\nof phase diagram) method."
    },
    {
        "anchor": "Electronic structure of the (111) and (-1-1-1) surfaces of cubic BN: A\n  local-density-functional ab initio study: We present ab initio local-density-functional electronic structure\ncalculations for the (111) and (-1-1-1) surfaces of cubic BN. The energetically\nstable reconstructions, namely the N adatom, N3 triangle models on the (111),\nthe (2x1), boron and nitrogen triangle patterns on the (-1-1-1) surface are\ninvestigated. Band structure and properties of the surface states are discussed\nin detail.",
        "positive": "Large magnetoelectric effect in mechanically mediated structure of\n  TbFe2, Pb(Zr,Ti)O3 and nonmagnetic flakes: Magnetoelectric (ME) effect has been studied in a structure of a\nmagnetostrictive TbFe2 alloy, two piezoelectric Pb(Zr,Ti)O3 (PZT) ceramics, and\ntwo nonmagnetic flakes. The ME coupling originates from the\nmagnetic-mechanical-electric transform of the magnetostrictive effect in TbFe2\nand the piezoelectric effect in PZT by end bonding, instead of interface\nbonding. Large ME coefficients of 10.5 and 9.9 Vcm-1Oe-1 were obtained at the\nfirst planar acoustic and third bending resonance frequencies, which are larger\nthan that of conventional layered TbFe2/PZT composites. The results show that\nthe large ME coupling can be achieved without interface coupling."
    },
    {
        "anchor": "Influence of morphology on the plasmonic enhancement effect of Au@TiO2\n  core-shell nanoparticles in dye-sensitized solar cells: Plasmonic core-shell nanoparticles (PCSNPs) can function as nanoantennas and\nimprove the efficiency of dye-sensitized solar cells (DSSCs). To achieve\nmaximum enhancement, the morphology of PCSNPs need to be optimized. Here we\nprecisely control the morphology of Au@TiO2 PCSNPs and systematically study its\ninfluence on the plasmonic enhancement effect. Enhancement mechanism was found\nto vary with the thickness of TiO2 shell. PCSNPs with thinner shell enhance the\ncurrent due to plasmonic effect, whereas particles with thicker shell improve\nthe voltage due to increasing semiconducting character. Wavelength-independent\nenhancement in the visible range was observed and attributed to plasmonic\nheating effect. PCSNPs with 5-nm shell give highest efficiency enhancement of\n23%. Our work provides a new synthesis route for well-controlled Au@TiO2\ncore-shell nanoparticles and gains insight into the plasmonic enhancement in\nDSSCs.",
        "positive": "Oxygen vacancy formation energies in Sr-doped complex perovskites: ab\n  initio thermodynamic study: La1-xSrxCo0.25Fe0.75O3-delta is known as one of the best cathode materials\nfor permeation membranes and solid oxide fuel cells. Optimization of its\nchemical composition is a challenging problem. One of the key properties is\nconcentration of oxygen vacancies, controlled by their formation energies. Ab\ninitio calculations were employed in order to study the formation of oxygen\nvacancies in La1-xSrxCo0.25Fe0.75O3-delta perovskites by varying the Sr content\nfrom x = 12.5% to 50%. The formation energies were obtained for different\nstoichiometries as functions of temperature and oxygen partial pressure. We\nhave shown that the phonon contribution to the free formation energy becomes\nincreasingly important in La1-xSrxCo0.25Fe0.75O3-delta not only with rising\ntemperature but also with rising Sr content. We have shown that the formation\nenergies are decreased significantly with increasing Sr content due to two\neffects: charge compensation of Sr2+ ions and phonon contribution. We have\nsuggested a simple explanation to increasing role of phonons for the oxygen\nvacancies formation energies on the basis of phonon mode changes in comparison\nto defect-free materials. A careful analysis of the experimental results from\nthe literature is also presented."
    },
    {
        "anchor": "Hydrogen/nitrogen/oxygen defect complexes in silicon from computational\n  searches: Point defect complexes in crystalline silicon composed of hydrogen, nitrogen,\nand oxygen atoms are studied within density-functional theory (DFT). Ab initio\nRandom Structure Searching (AIRSS) is used to find low-energy defect\nstructures. We find new lowest-energy structures for several defects: the\ntriple-oxygen defect, {3O}, triple oxygen with a nitrogen atom, {N, 3O}, triple\nnitrogen with an oxygen atom, {3N,O}, double hydrogen and an oxygen atom,\n{2H,O}, double hydrogen and oxygen atoms, {2H,2O} and four\nhydrogen/nitrogen/oxygen complexes, {H,N,O}, {2H,N,O}, {H,2N,O} and {H,N,2O}.\nWe find that some defects form analogous structures when an oxygen atom is\nreplaced by a NH group, for example, {H,N,2O} and {3O}, and {H,N} and {O}. We\ncompare defect formation energies obtained using different oxygen chemical\npotentials and investigate the relative abundances of the defects.",
        "positive": "Omnidirectional refractive devices for flexural waves based on graded\n  phononic crystals: Different omnidirectional refractive devices for flexural waves in thin\nplates are proposed and numerically analyzed. Their realization is explained by\nmeans phononic crystal plates, where a previously developed homogenization\ntheory is employed for the design of graded index refractive devices. These\ndevices consist of a circular cluster of inclusions with properly designed\ngradient in their radius. With this approach, the Luneburg and Maxwell lenses\nand a family of beam splitters for flexural waves are proposed and analyzed.\nResults show that these devices work properly in a broadband frequency region,\nbeing therefore an efficient approach for the design of refractive devices\nspecially interesting for nano-scale applications."
    },
    {
        "anchor": "Magnetic and structural properties of nanocrystalline PrCo$_3$: The structure and magnetic properties of nanocrystalline PrCo$_3$ obtained\nfrom high energy milling technique are investigated by X-ray diffraction, Curie\ntemperature determination and magnetic properties measurements are reported.\nThe as-milled samples have been annealed in a temperature range of 1023 K to\n1273 K for 30 mn to optimize the extrinsic properties. The Curie temperature is\n349\\,K and coercive fields of 55\\,kOe at 10\\,K and 12\\,kOe at 293\\,K are\nobtained on the samples annealed at 1023\\,K. A simulation of the magnetic\nproperties in the framework of micromagnetism has been performed in order to\ninvestigate the influence of the nanoscale structure. A composite model with\nhard crystallites embedded in an amorphous matrix, corresponding to the\nas-milled material, leads to satisfying agreement with the experimental\nmagnetization curve. [ K. Younsi, V. Russier and L. Bessais, J. Appl. Phys.\n{\\bf 107}, 083916 (2010)]. The microscopic scale will also be considered from\nDFT based calculations of the electronic structure of $R$Co$_x$ compounds,\nwhere $R$ = (Y, Pr) and $x$ = 2,3 and 5.",
        "positive": "A jigsaw puzzle metamaterial concept: A concept of a planar modular mechanical metamaterial inspired by the\nnature's principle of local adaptivity is proposed. The metamaterial consists\nof identical pieces similar to jigsaw puzzle tiles. Their rotation within\nassembly provides a substantial flexibility in terms of structural behavior and\nmechanical interlocks enable reassembly. The tile design with a diagonal\nelliptical opening allows us to vary elastic properties--from stiff to\ncompliant, with positive, zero, or negative Poisson's ratio. The outcomes of\nexperimental testing on additively manufactured specimens confirm that the\nassembly properties can be accurately designed using optimization approaches\nwith finite element analysis at heart."
    },
    {
        "anchor": "Hidden kagome-lattice picture and origin of high conductivity in\n  delafossite PtCoO$_2$: We study the electronic structure of delafossite PtCoO$_2$ to elucidate its\nextremely small resistivity and high mobility. The band exhibits steep\ndispersion near the Fermi level despite the fact that it is formed mainly by Pt\n$d$ orbitals that are typically localized. We propose a picture based on two\nhidden kagome-lattice-like electronic structure: one originating from Pt\n$s+p_x/p_y$ orbitals, and the other from Pt $d_{3z^2-r^2}+d_{xy}/d_{x^2-y^2}$\norbitals, each placed on the bonds of the triangular lattice. In particular, we\nfind that the underlying Pt $s+p_x/p_y$ bands actually determine the steepness\nof the original dispersion, so that the large Fermi velocity can be attributed\nto the large width of the Pt $s+p_x/p_y$ band. More importantly, the\nkagome-like electronic structure gives rise to \"orbital-momentum locking\" on\nthe Fermi surface, which reduces the electron scattering by impurities. We\nconclude that the combination of the large Fermi velocity and the\norbital-momentum locking is likely to be the origin of the extremely small\nresistivity in PtCoO$_2$.",
        "positive": "Tunable magnetic and transport properties of Mn3Ga thin films on Ta/Ru\n  seedlayer: Hexagonal D019-type Mn3Z alloys that possess large anomalous and\ntopological-like Hall effects have attracted much attention due to their great\npotential in the antiferromagnetic spintronic devices. Here, we report the\npreparation of Mn3Ga film in both tetragonal and hexagonal phases with a tuned\nTa/Ru seed layer on the thermally oxidized Si substrate. A large coercivity\ntogether with a large anomalous Hall resistivity is found in the Ta-only sample\nwith mixed tetragonal phase. By increasing the thickness of Ru layer, the\ntetragonal phase gradually disappears and a relatively pure hexagonal phase is\nobtained in the Ta(5)/Ru(30) buffered sample. Further magnetic and transport\nmeasurements revealed that the anomalous Hall conductivity nearly vanishes in\nthe pure hexagonal sample, while an abnormal asymmetric hump structure emerges\nin the low field region. The extracted additional Hall term is robust in a\nlarge temperature range and presents a sign reversal above 200K. The abnormal\nHall properties are proposed to be closely related with the frustrated spin\nstructure of D019 Mn3Ga."
    },
    {
        "anchor": "Tilted Spirals and Low Temperature Skyrmions in Cu2OSeO3: The bulk helimagnet Cu2OSeO3 represents a unique example in the family of B20\ncubic helimagnets exhibiting a tilted spiral and skyrmion phase at low\ntemperatures when the magnetic field is applied along the easy <001>\ncrystallographic direction. Here we present a systematic study of the stability\nand ordering of these low temperature magnetic states. We focus our attention\non the temperature and field dependencies of the tilted spiral state that we\nobserve persisting up to above T =35 K, i.e. up to higher temperatures than\nreported so far. We discuss these results in the frame of the phenomenological\ntheory introduced by Dzyaloshinskii in an attempt to reach a quantitative\ndescription of the experimental findings. We find that the anisotropy\nconstants, which are the drivers behind the observed behaviour, exhibit a\npronounced temperature dependence. This explains the differences in the\nbehaviour observed at high temperatures (above T = 18 K), where the cubic\nanisotropy is weak, and at low temperatures (below T = 18 K), where a strong\ncubic anisotropy induces an abrupt appearance of the tilted spirals out of the\nconical state and enhances the stability of skyrmions.",
        "positive": "Transport mechanism through metal-cobaltite interfaces: The resistive switching (RS) properties as a function of temperature were\nstudied for Ag/La$_{1-x}$Sr$_x$CoO$_3$ (LSCO) interfaces. The LSCO is a\nfully-relaxed 100 nm film grown by metal organic deposition on a LaAlO$_3$\nsubstrate. Both low and a high resistance states were set at room temperature\nand the temperature dependence of their current-voltage (IV) characteristics\nwas mea- sured taking care to avoid a significant change of the resistance\nstate. The obtained non-trivial IV curves of each state were well reproduced by\na circuit model which includes a Poole-Frenkel element and two ohmic\nresistances. A microscopic description of the changes produced by the RS is\ngiven, which enables to envision a picture of the interface as an area where\nconductive and insulating phases are mixed, producing Maxwell-Wagner\ncontributions to the dielectric properties."
    },
    {
        "anchor": "Spin-wave spectroscopy on Dzyaloshinskii-Moriya interaction in\n  room-temperature chiral magnets hosting skyrmions: Propagation character of spin wave was investigated for chiral magnets FeGe\nand Co-Zn-Mn alloys, which can host magnetic skyrmions near room temperature.\nOn the basis of the frequency shift between counter-propagating spin waves, the\nmagnitude and sign of Dzyaloshinskii-Moriya (DM) interaction were directly\nevaluated. The obtained magnetic parameters quantitatively account for the size\nand helicity of skyrmions as well as their materials variation, proving that\nthe DM interaction plays a decisive role in the skyrmion formation in this\nclass of room-temperature chiral magnets. The propagating spin-wave\nspectroscopy can thus be an efficient tool to study DM interaction in bulk\nsingle-phase compounds. Our results also demonstrate a function of spin-wave\ndiode based on chiral crystal structures at room temperature.",
        "positive": "One- and two-magnon excitations in antiferromagnet PbFeBO4: The linear spin-wave theory study of PbFeBO4 spin dynamics is presented. It\nis shown that the modes observed in Raman scattering experiments below Neel\ntemperature are optical magnon and two-magnon excitations. Based on the magnon\nenergy, two-magnon band lineshape, and Weiss temperature, the consistent set of\nthe exchange coupling constants up the third neighbor is derived and compared\nwith the results of ab initio calculations. The small deviation of the observed\ntwo-magnon band from the one-magnon density of states suggests a surprisingly\nnegligible role of magnon-magnon interactions."
    },
    {
        "anchor": "Uniting Weyl semimetals and semiconductors in a family of arsenides: In this preview, we discuss how to combine concepts of Weyl fermions, amazing\nelectronic properties of bulk Weyl semimetals, and advances in molecular beam\nepitaxy with the needs of semiconductor industry, through the fabrication of\nTaAs thin films.",
        "positive": "Realization of face-shear piezoelectric coefficient d36 in PZT ceramics\n  via ferroelastic domain engineering: The piezoelectric face-shear (d36) mode may be the most useful shear mode in\npiezoelectrics, while currently this mode can only exist in single crystals of\nspecific point groups and cut directions. Theoretically the d36 coefficient\nvanishes in piezoelectric ceramics because of its transversally isotropic\nsymmetry . In this work, we modified the symmetry of poled PZT ceramics from\ntransversally isotropic to orthogonal through ferroelastic domain switching by\napplying a high lateral stress along the \"2\" direction and holding the stress\nfor several hours. After removing the compression, the piezoelectric\ncoefficient d31 is found much larger than d32. Then by cutting the compressed\nsample along the zxt+45 deg direction, we realized d36 coefficients up to 206\npC/N which is measured by using a modified d33 meter. The obtained large d36\ncoefficients in PZT ceramics could be very promising for face-shear mode\nresonators and shear horizontal (SH) wave generation in nondestructive testing."
    },
    {
        "anchor": "Ultrafast lattice deformations studied by means of time-resolved\n  electron and x-ray diffraction: Ultrafast lattice deformation of tens to hundreds of nanometer thick metallic\ncrystals, after femtosecond laser excitation, was measured directly using 8.04\nkeV subpicosecond x-ray and 59 keV femtosecond electron pulses. Coherent\nphonons were generated in both single crystal and polycrystalline films.\nLattice compression was observed within the first few picoseconds after laser\nirradiation in single crystal aluminum, which was attributed to the generation\nof a blast force and the propagation of elastic waves. The different time scale\nof lattice heating for tens and hundreds nanometer thick films are clearly\ndistinguished by electron and x-ray pulse diffraction. The electron and lattice\nheating due to ultrafast deposition of photon energy was numerically simulated\nusing the two-temperature model (TTM) and the results agreed with experimental\nobservations. The ultrafast heating described by TTM was also discussed from an\nelectrical circuit perspective, which may provide new insights on the possible\nconnection between thermal and electrical processes. This study demonstrates\nthat the combination of two complimentary ultrafast time-resolved methods,\nultrafast x-ray and electron diffraction will provide a panoramic picture of\nthe transient atomic motions and structure in crystals.",
        "positive": "Interplay of Inhomogeneous Electrochemical Reactions with Mechanical\n  Responses in Silicon-Graphite Anode and its Impacts on Degradation: Enhanced EV market penetration requires durability of the battery with high\nenergy throughput. For long-term cycle stability of silicon-graphite anode\ncapable of high energy density, the reversible redox reactions are crucial.\nHere, we unveil intriguing electrochemical phenomena such as crosstalk of\nlithium ion ($Li^{+}$) between silicon and graphite, $Li^{+}$ accumulation in\nsilicon, and capacity depression of graphite under high pressure, which\nengender the irreversible redox reactions. Active material properties, i.e. the\nsize of silicon and the hardness of graphite, silicon-graphite anode, are\nmodified based on the unveiled results to enhance the reaction homogeneity and\nreduce subsequent degradation. Owing to the property change of the anode active\nmaterials, silicon-graphite anode paired with high nickel cathode allows the\nprismatic cell with 8.7 Ah to reach cycling performance over 750 cycles with\nvolumetric energy density of 665 $Whl^{-1}$, which is corresponding to 800\n$Whl^{-1}$ in the prismatic cell with 87 Ah. Finally, the cycling performance\ncan be tailored by the design of electrode regulating $Li^{+}$ crosstalk. Our\nfindings provide electrochemical insights into degradation mechanisms and a\npromising direction on the progressive improvement of materials and the design\nof electrodes in silicon-graphite anode."
    },
    {
        "anchor": "Magnetic coupling in Y$_3$Fe$_5$O$_{12}$/Gd$_3$Fe$_5$O$_{12}$\n  heterostructures: Ferrimagnetic Y$_3$Fe$_5$O$_{12}$ (YIG) is the prototypical material for\nstudying magnonic properties due to its exceptionally low damping. By\nsubstituting the yttrium with other rare earth elements that have a net\nmagnetic moment, we can introduce an additional spin degree of freedom. Here,\nwe study the magnetic coupling in epitaxial\nY$_3$Fe$_5$O$_{12}$/Gd$_3$Fe$_5$O$_{12}$ (YIG/GIG) heterostructures grown by\npulsed laser deposition. From bulk sensitive magnetometry and surface sensitive\nspin Seebeck effect (SSE) and spin Hall magnetoresistance (SMR) measurements,\nwe determine the alignment of the heterostructure magnetization through\ntemperature and external magnetic field. The ferromagnetic coupling between the\nFe sublattices of YIG and GIG dominates the overall behavior of the\nheterostructures. Due to the temperature dependent gadolinium moment, a\nmagnetic compensation point of the total bilayer system can be identified. This\ncompensation point shifts to lower temperatures with increasing thickness of\nYIG due the parallel alignment of the iron moments. We show that we can control\nthe magnetic properties of the heterostructures by tuning the thickness of the\nindividual layers, opening up a large playground for magnonic devices based on\ncoupled magnetic insulators. These devices could potentially control the magnon\ntransport analogously to electron transport in giant magnetoresistive devices.",
        "positive": "Theoretical evidence for efficient p-type doping of GaN using beryllium: Ab initio calculations predict that Be is a shallow acceptor in GaN. Its\nthermal ionization energy is 0.06 eV in wurtzite GaN; the level is valence\nresonant in the zincblende phase. Be incorporation is severely limited by the\nformation of Be_3N_2. We show however that co-incorporation with reactive\nspecies can enhance the solubility. H-assisted incorporation should lead to\nhigh doping levels in MOCVD growth after post-growth annealing at about 850 K.\nBe-O co-incorporation produces high Be and O concentrations at MBE growth\ntemperatures."
    },
    {
        "anchor": "Multi-state data storage in a two-dimensional stripy antiferromagnet\n  implemented by magnetoelectric effect: A promising approach to the next generation of low-power, functional, and\nenergy-efficient electronics relies on novel materials with coupled magnetic\nand electric degrees of freedom. In particular, stripy antiferromagnets often\nexhibit broken crystal and magnetic symmetries, which may bring about the\nmagnetoelectric (ME) effect and enable the manipulation of intriguing\nproperties and functionalities by electrical means. The demand for expanding\nthe boundaries of data storage and processing technologies has led to the\ndevelopment of spintronics toward two-dimensional (2D) platforms. This work\nreports the ME effect in the 2D stripy antiferromagnetic insulator CrOCl down\nto a single layer. By measuring the tunneling resistance of CrOCl on the\nparameter space of temperature, magnetic field, and applied voltage, we\nverified the ME coupling down to the 2D limit and unraveled its mechanism.\nUtilizing the multi-stable states and ME coupling at magnetic phase\ntransitions, we realize multi-state data storage in the tunneling devices. Our\nwork not only advances the fundamental understanding of spin-charge coupling\nbut also demonstrates the great potential of 2D antiferromagnetic materials to\ndeliver devices and circuits beyond the traditional binary operations.",
        "positive": "Observation of magnetism induced topological edge state in\n  antiferromagnetic topological insulator MnBi4Te7: Breaking time reversal symmetry in a topological insulator may lead to\nquantum anomalous Hall effect and axion insulator phase. MnBi4Te7 is a recently\ndiscovered antiferromagnetic topological insulator with TN ~12.5 K, which is\nconstituted of alternatively stacked magnetic layer (MnBi2Te4) and non-magnetic\nlayer (Bi2Te3). By means of scanning tunneling spectroscopy, we clearly observe\nthe electronic state present at a step edge of a magnetic MnBi2Te4 layer but\nabsent at non-magnetic Bi2Te3 layers at 4.5 K. Furthermore, we find that as the\ntemperature rises above TN, the edge state vanishes, while the point defect\ninduced state persists upon temperature increasing. These results confirm the\nobservation of magnetism induced edge states. Our analysis based on an axion\ninsulator theory reveals that the nontrivial topological nature of the observed\nedge state."
    },
    {
        "anchor": "Turning non-magnetic two-dimensional molybdenum disulfide into room\n  temperature magnets by the synergistic effect of strain engineering and\n  charge injection: The development of two-dimensional (2D) room temperature magnets is of great\nsignificance to the practical application of spintronic devices. However, the\nnumber of synthesized intrinsic 2D magnets is limited and the performances of\nthem are not satisfactory, e.g. typically with low Curie temperature and poor\nenvironmental stability. Magnetic modulation based on developed 2D materials,\nespecially non-magnetic 2D materials, can bring us new breakthroughs. Herein,\nwe report room temperature ferromagnetism in halogenated MoS2 monolayer under\nthe synergistic effect of strain engineering and charge injection, and the\ncombined implementation of these two processes is based on the halogenation of\nMoS2. The adsorbed halogen atoms X (X = F, Cl, and Br) on the surface leads to\nlattice superstretching and hole injection, resulting in MoS2 monolayer\nexhibiting half-metallic properties, with one spin channel being gapless in the\nband structure. The Curie temperature of halogenated MoS2 monolayer is 513~615\nK, which is much higher than the room temperature. In addition, large magnetic\nanisotropy energy and good environmental stability make halogenated MoS2\ndisplay great advantages in practical spintronic nanodevices.",
        "positive": "Optimized effective potential method and application to static RPA\n  correlation: The optimized effective potential (OEP) method is a promising technique for\ncalculating the ground state properties of a system within the density\nfunctional theory. However, it is not widely used as its computational cost is\nrather high and, also, some ambiguity remains in the theoretical framework. In\norder to overcome these problems, we first introduced a method that accelerates\nthe OEP scheme in a static RPA-level correlation functional. Second, the\nKrieger-Li-Iafrate (KLI) approximation is exploited to solve the OEP equation.\nAlthough seemingly too crude, this approximation did not reduce the accuracy of\nthe description of the magnetic transition metals (Fe, Co, and Ni) examined\nhere, the magnetic properties of which are rather sensitive to correlation\neffects. Finally, we reformulated the OEP method to render it applicable to the\ndirect RPA correlation functional and other, more precise, functionals.\nEmphasis is placed on the following three points of the discussion: i)\nLevel-crossing at the Fermi surface is taken into account; ii) eigenvalue\nvariations in a Kohn-Sham functional are correctly treated; and iii) the\nresultant OEP equation is different from those reported to date."
    },
    {
        "anchor": "Reducing sheet resistance of self-assembled transparent graphene films\n  by defect patching and doping with UV/ozone treatment: Liquid phase exfoliation followed by Langmuir-Blodgett self-assembly (LBSA)\nis a promising method for scalable production of thin graphene films for\ntransparent conductor applications. However, monolayer assembly into thin films\noften induces a high density of defects, resulting in a large sheet resistance\nthat hinders practical use. We introduce UV/ozone as a novel photochemical\ntreatment that reduces sheet resistance of LBSA graphene threefold, while\npreserving the high optical transparency. The effect of such treatment on our\nfilms is opposite to the effect it has on mechanically exfoliated or CVD films,\nwhere UV/ozone creates additional defects in the graphene plane, increasing\nsheet resistance. Raman scattering shows that exposure to UV/ozone reduces the\ndefect density in LBSA graphene, where edges are the dominant defect type. FTIR\nspectroscopy indicates binding of oxygen to the graphene lattice during\nexposure to ozone. In addition, work function measurements reveal that the\ntreatment dopes the LBSA film, making it more conductive. Such defect patching\npaired with doping leads to an accessible way of improving the transparent\nconductor performance of LBSA graphene, making solution-processed thin films a\ncandidate for industrial use.",
        "positive": "From Fundamental First-Principle Calculations to NanoEngineering\n  Applications: Review of the NESSIE project: This paper outlines how modern first-principle calculations can adequately\naddress the needs for ever higher levels of numerical accuracy and\nhigh-performance in large-scale electronic structure simulations, and pioneer\nthe fundamental study of quantum many-body effects in a large number of\nemerging nanomaterials."
    },
    {
        "anchor": "Single photon emitters in hexagonal boron nitride: A review of progress: This report summarizes progress made in understanding properties such as\nzero-phonon-line energies, emission and absorption polarizations,\nelectron-phonon couplings, strain tuning and hyperfine coupling of single\nphoton emitters in hexagonal boron nitride. The primary aims of this research\nare to discover the chemical nature of the emitting centres and to facilitate\ndeployment in device applications. Critical analyses of the experimental\nliterature and data interpretation, as well as theoretical approaches used to\npredict properties, are made. In particular, computational and theoretical\nlimitations and challenges are discussed, with a range of suggestions made to\novercome these limitations, striving to achieve realistic predictions\nconcerning the nature of emitting centers. A symbiotic relationship is required\nin which calculations focus on properties that can easily be measured, whilst\nexperiments deliver results in a form facilitating mass-produced calculations.",
        "positive": "Exploring the effect of varying regime of ion fluence on optical and\n  surface electronic properties of CVD Grown Graphene: In this work, the effect of the ion fluence-dependent defect formation on the\nmodification of surface electronic and optical properties of graphene has been\ninvestigated. The chemical vapor deposited (CVD) graphene was irradiated with\nswift heavy ion (SHI) (70 MeV Si+5) beam at different fluence to study the\ndefect formation mechanism and the role of it in modulating its surface\nelectronic property such as work function. At low ion dose, acceptor doping via\nvacancy creation was observed; whereas dense electronic excitation dominated\nextended defects was realized at higher dose, which subsequently transforms the\ncrystalline graphene into amorphous carbon. The results from UV-Vis\nspectroscopy, Raman spectroscopy and scanning Kelvin probe microscopy (SKPM)\nsupport the fact. Thus a new pathway of transformation of graphene under SHI\nirradiation was explored where ion dose could be the main factor to realize\nseveral effects in graphene."
    },
    {
        "anchor": "Probing the photonic local density of states with electron energy loss\n  spectroscopy: Electron energy-loss spectroscopy (EELS) performed in transmission electron\nmicroscopes is shown to directly render the photonic local density of states\n(LDOS) with unprecedented spatial resolution, currently below the nanometer.\nTwo special cases are discussed in detail: (i) 2D photonic structures with the\nelectrons moving along the translational axis of symmetry and (ii) quasi-planar\nplasmonic structures under normal incidence. Nanophotonics in general and\nplasmonics in particular should benefit from these results connecting the\nunmatched spatial resolution of EELS with its ability to probe basic optical\nproperties like the photonic LDOS.",
        "positive": "The spin-state crossover and low-temperature magnetic state in yttrium\n  doped Pr$_{0.7}$Ca$_{0.3}$CoO$_3$: The structural and magnetic properties of two mixed-valence cobaltites with\nformal population of 0.30 Co$^{4+}$ ions per f.u.,\n(Pr$_{1-y}$Y$_{y}$)$_{0.7}$Ca$_{0.3}$CoO$_3$ ($y=0$ and 0.15), have been\nstudied down to very low temperatures by means of the high-resolution neutron\ndiffraction, SQUID magnetometry and heat capacity measurements. The results are\ninterpreted within the scenario of the spin-state crossover from a\nroom-temperature mixture of the intermediate spin Co$^{3+}$ and low spin\nCo$^{4+}$ (IS/LS) at the to the LS/LS mixture in the sample ground states. In\ncontrast to the yttrium free $y=0$ that retains the metallic-like character and\nexhibits ferromagnetic ordering below 55 K, the doped system $y=0.15$ undergoes\na first-order metal-insulator transition at 132 K, during which not only the\ncrossover to low spin states but also a partial electron transfer from\nPr$^{3+}$ 4f to cobalt 3d states take place simultaneously. Taking into account\nthe non-magnetic character of LS Co$^{3+}$, such valence shift electronic\ntransition causes a magnetic dilution, formally to 0.12 LS Co$^{4+}$ or 0.12\n$t_{2g}$ hole spins per f.u., which is the reason for an insulating, highly\nnon-uniform magnetic ground state without long-range order. Nevertheless, even\nin that case there exists a relatively strong molecular field distributed over\nall the crystal lattice. It is argued that the spontaneous FM order in $y=0$\nand the existence of strong FM correlations in $y=0.15$ apparently contradict\nthe single $t_{2g}$ band character of LS/LS phase. The explanation we suggest\nrelies on a model of the defect induced, itinerant hole mediated magnetism,\nwhere the defects are identified with the magnetic high-spin Co$^{3+}$ species\nstabilized near oxygen vacancies."
    },
    {
        "anchor": "A period-doubled structure for the 90-degree partial dislocation in\n  silicon: We suggest that the commonly-accepted core structure of the 90-degree partial\ndislocation in Si may not be correct, and propose instead a period-doubled\nstructure. We present LDA, tight-binding, and classical Keating-model\ncalculations, all of which indicate that the period-doubled structure is lower\nin energy. The new structure displays a broken mirror symmetry in addition to\nthe period doubling, leading to a wide variety of possible soliton-like defects\nand kinks.",
        "positive": "Interface induced perpendicular magnetic anisotropy in Co/CoO/Co thin\n  film structure: An in-situ MOKE investigation: Co /CoO/Co polycrystalline film was grown on Si (001) substrate and magnetic\nproperties have been investigated using in-situ magneto-optic Kerr effect\nduring growth of the sample. Magnetic anisotropy with easy axis perpendicular\nto the film surface has been observed in top Co layer, whereas bottom layer was\nfound to be soft with in-plane magnetization without any influence of top\nlayer. Ex-situ in-plane and out-of-plane diffraction measurements revealed that\nthe growth of Co on oxidized interface takes place with preferential\norientation of c-axis perpendicular to the film plane, which results in the\nobserved perpendicular magnetic anisotropy. Texturing of the c-axis is expected\nto be a result of minimization of the interface energy due to hybridization\nbetween Co and oxygen at the interface."
    },
    {
        "anchor": "Valence electronic structure of Mn in undoped and doped lanthanum\n  manganites from relative K x-ray intensity studies: Relative $K$ x-ray intensities of $Mn$ in $Mn$, $MnO_{2}$, $LaMnO_{3}$ and\n$La_{0.7}B_{0.3}MnO_{3}$ ($B$ = $Ca$, $Sr$, and $Ce$) systems have been\nmeasured following excitation by 59.54 keV $\\gamma$-rays from a 200 mCi\n$^{241}$Am point-source. The measured results for the compounds deviate\nsignificantly from the results of pure $Mn$. Comparison of the experimental\ndata with the multiconfiguration Dirac-Fock (MCDF) effective atomic model\ncalculations indicates reasonable agreement with the predictions of ionic model\nfor the doped {manganites except} that the electron doped\n$La_{0.7}Ce_{0.3}MnO_{3}$ and hole doped $La_{0.7}Ca_{0.3}MnO_{3}$ compounds\nshow some small deviations. The results of $MnO_{2}$ and $LaMnO_{3}$ deviate\nconsiderably from the predictions of the ionic model. Our measured\n$K\\beta/K\\alpha$ ratio of $Mn$ in $La_{0.7}Ca_{0.3}MnO_{3}$ cannot be explained\nas a linear superposition of $K\\beta/K\\alpha$ ratios of $Mn$ for the end\nmembers which is in contrast to the recent proposal by Tyson et al. from their\n$Mn$ $K\\beta$ spectra.",
        "positive": "Crystal structure and electronic structure of quaternary semiconductors\n  Cu$_2$ZnTiSe$_4$ and Cu$_2$ZnTiS$_4$ for solar cell absorber: We design two new I2-II-IV-VI4 quaternary semiconductors Cu$_2$ZnTiSe$_4$ and\nCu$_2$ZnTiS$_4$, and systematically study the crystal and electronic structure\nby employing first-principles electronic structure calculations. Among the\nconsidered crystal structures, it is confirmed that the band gaps of\nCu$_2$ZnTiSe$_4$ and Cu$_2$ZnTiS$_4$ originate from the full occupied Cu 3$d$\nvalence band and unoccupied Ti 3$d$ conducting band, and kesterite structure\nshould be the ground state. Furthermore, our calculations indicate that\nCu$_2$ZnTiSe$_4$ and Cu$_2$ZnTiS$_4$ have comparable band gaps with\nCu$_2$ZnTSe$_4$ and Cu$_2$ZnTS$_4$, but almost twice larger absorption\ncoefficient $\\alpha(\\omega)$. Thus, the materials are expected to be candidate\nmaterials for solar cell absorber."
    },
    {
        "anchor": "Magnon polarons in the spin Peltier effect: We report the observation of anomalous peak structures induced by hybridized\nmagnon-phonon excitation (magnon polarons) in the magnetic field dependence of\nthe spin Peltier effect (SPE) in a Lu$_{2}$Bi$_{1}$Fe$_{4}$Ga$_{1}$O$_{12}$\n(BiGa:LuIG) with Pt contact. The SPE peaks coincide with magnetic fields tuned\nto the threshold of magnon-polaron formation, consistent with the previous\nobservation in the spin Seebeck effect. The enhancement of SPE is attributed to\nthe lifetime increase in spin current caused by magnon-phonon hybridization in\nBiGa:LuIG.",
        "positive": "Strongly Enhanced Curie Temperature in Carbon-Doped Mn5Ge3 Films: The structural and magnetic properties of Mn5Ge3Cx films prepared at elevated\nsubstrate temperatures TS are investigated. In particular, films with x >= 0.5\nand TS = 680 K exhibit a strongly enhanced Curie temperature TC = 440 K\ncompared to Mn5Ge3 with TC = 304 K. Structural analysis of these films suggests\nthat the carbon is interstitially incorporated into the voids of Mn octahedra\nof the hexagonal Mn5Si3-type structure giving rise to a lattice compression.\nThe enhanced ferromagnetic stability in connection with the lattice compression\nis interpreted in terms of an Mn-Mn interaction mediated by C based on a change\nin the electronic structure."
    },
    {
        "anchor": "Tunneling spectroscopy studies of aluminum oxide tunnel barrier layers: We report scanning tunneling microscopy and ballistic electron emission\nmicroscopy studies of the electronic states of the uncovered and\nchemisorbed-oxygen covered surface of AlOx tunnel barrier layers. These states\nchange when chemisorbed oxygen ions are moved into the oxide by either flood\ngun electron bombardment or by thermal annealing. The former, if sufficiently\nenergetic, results in locally well defined conduction band onsets at ~1 V,\nwhile the latter results in a progressively higher local conduction band onset,\nexceeding 2.3 V for 500 and 600 C thermal anneals.",
        "positive": "A machine learning-based selective sampling procedure for identifying\n  the low energy region in a potential energy surface: a case study on proton\n  conduction in oxides: In this paper, we propose a selective sampling procedure to preferentially\nevaluate a potential energy surface (PES) in a part of the configuration space\ngoverning a physical property of interest. The proposed sampling procedure is\nbased on a machine learning method called the Gaussian process (GP), which is\nused to construct a statistical model of the PES for identifying the region of\ninterest in the configuration space. We demonstrate the efficacy of the\nproposed procedure for atomic diffusion and ionic conduction, specifically the\nproton conduction in a well-studied proton-conducting oxide, barium zirconate\nBaZrO3. The results of the demonstration study indicate that our procedure can\nefficiently identify the low-energy region characterizing the proton conduction\nin the host crystal lattice, and that the descriptors used for the statistical\nPES model have a great influence on the performance."
    },
    {
        "anchor": "Molecular Dynamics Study of Ferroelectric Perovskites based on Effective\n  Hamiltonians: implementation of Nose-Hoover and Parinello-Rahman algorithms: Molecular Dynamics is applied to Ferroelectric Perovskites in the framework\nof a first-principles derived effective Hamiltonian (Zhong, Vanderbilt, Rabe,\nPhys. Rev. Lett. {\\bf 73} (1994), 1861). The degrees of freedom, that obey the\nNewton equations of motion, are the local modes and the displacement modes. The\nNose-Hoover method is implemented, as well as the Parinello-Rahman scheme to\nperform fixed temperature and fixed stress tensor simulations. This allows to\nstudy the thermodynamics of ferroelectric perovskites and to reproduce\nsuccessfully the Monte Carlo results on phase transitions, polarization and\nhomogeneous strain evolution with temperature of BaTiO$_3$, taken as an\nexample.",
        "positive": "Spin and Valley Polarized Multiple Fermi Surfaces of\n  \u03b1-RuCl$_3$/Bilayer Graphene Heterostructure: We report the transport properties of ${\\alpha}$-RuCl$_3$/bilayer graphene\nheterostructures, where carrier doping is induced by a work function\ndifference, resulting in distinct electron and hole populations in\n${\\alpha}$-RuCl3 and bilayer graphene, respectively. Through a comprehensive\nanalysis of multi-channel transport signatures, including Hall measurements and\nquantum oscillation, we unveil significant band modifications within the\nsystem. In particular, we observe the emergence of spin and valley polarized\nmultiple hole-type Fermi pockets, originating from the spin-selective band\nhybridization between ${\\alpha}$-RuCl$_3$ and bilayer graphene, breaking the\nspin degree of freedom. Unlike ${\\alpha}$-RuCl$_3$ /monolayer graphene system,\nthe presence of different hybridization strengths between ${\\alpha}$-RuCl$_3$\nand the top and bottom graphene layers leads to an asymmetric behavior of the\ntwo layers, confirmed by effective mass experiments, resulting in the\nmanifestation of valley-polarized Fermi pockets. These compelling findings\nestablish ${\\alpha}$-RuCl$_3$ proximitized to bilayer graphene as an\noutstanding platform for engineering its unique low-energy band structure."
    },
    {
        "anchor": "Comment on \"Tunable Band Gaps in Bilayer Graphene-BN Heterostructures\": We study the electronic properties of h-BN/graphene/h-BN ABC-stacked trilayer\nsystems using tight binding and DFT methods. We comment on the recent work of\nRamasubramaniam et al. (arxiv:1011.2489) whose results seem to be in\ndisagreement with our recent calculations. Detailed analysis reaffirms our\nprevious conclusions.",
        "positive": "Magnetoelectrical control of nonreciprocal microwave response in a\n  multiferroic helimagnet: Control of physical property in terms of external fields is essential for\ncontemporary technologies. The conductance can be controlled by a gate electric\nfield in a field effect transistor, which is a main component of the integrated\ncircuit. Optical phenomena induced by an electric field such as\nelectroluminescence and electrochromism are useful for display and other\ntechnologies. Control of microwave propagation seems also imperative for future\nwireless communication technology. Microwave properties in solids are dominated\nmostly by magnetic excitations, which cannot be easily controlled by an\nelectric field. One of the solutions for this problem is utilizing magnetically\ninduced ferroelectrics (multiferroics). Here we show that microwave\nnonreciprocity, which is difference between oppositely propagating microwaves,\ncan be reversed by the external electric field in a multiferroic helimagnet\nBa$_2$Mg$_2$Fe$_{12}$O$_{22}$. This result offers a new avenue for the\nelectrical control of microwave properties."
    },
    {
        "anchor": "DFT+U simulation of the Ti${}_4$O${}_7$-TiO${}_2$ interface: The formation of conducting channels of Ti${}_4$O${}_7$ inside\nTiO${}_2$-based memristors is believed to be the origin for the change in\nelectric resistivity of these devices. While the properties of the bulk\nmaterials are reasonably known, the interface between them has not been studied\nup to now mostly due to their different crystalline structures. In this work we\npresent a way to match the interfaces between TiO${}_2$ and Ti${}_4$O${}_7$ and\nsubsequently the band offset between these materials is obtained from density\nfunctional theory based calculations. The results show that while the valence\nband is located at the Ti${}_4$O${}_7$, the conduction band is found at the\nTiO${}_2$ structure, resulting into a type II interface. In this case, the\nTi${}_4$O${}_7$ would act as a donor to the TiO${}_2$ matrix.",
        "positive": "Designing of Magnetic MAB Phases for Energy Applications: Based on high-throughput density functional theory calculations, we performed\nscreening for stable magnetic MAB compounds and predicted potential strong\nmagnets for permanent magnet and magnetocaloric applications. The\nthermodynamical, mechanical, and dynamical stabilities are systematically\nevaluated, resulting in 21 unreported compounds on the convex hull, and 434\nmaterials being metastable considering convex hull tolerance to be 100\nmeV/atom. Analysis based on the Hume-Rothery rules revealed that the valence\nelectron concentration and size factor difference are of significant importance\nin determining the stability, with good correspondence with the local atomic\nbonding. We found 71 compounds with the absolute value of magneto-crystalline\nanisotropy energy above 1.0 MJ/m$^3$ and 23 compounds with a uniaxial\nanisotropy greater than 0.4 MJ/m$^3$, which are potential gap magnets. Based on\nthe magnetic deformation proxy, 99 compounds were identified as potential\nmaterials with interesting magnetocaloric performance."
    },
    {
        "anchor": "NQR of barium in BaBiO3 and BaPbO3: The NQR on Ba nuclei was studied in four samples of BaBiO3 prepared in\ndifferent ways and, in addition, in BaPbO3. The spectrum of $^{137}$Ba at T=4.2\nK consists of relatively broad line centered near 18 MHz for all BaBiO3 samples\nand near 13 MHz for BaPbO3. The integrated intensity of $^{137}$Ba resonance in\nceramic sample BaBiO3 synthesized at 800 C is approximately two times larger\nthan in ceramic samples and single crystal prepared at 930-1080 C. The decrease\nof the NQR signal can be attributed to the partial disordering of charge\ndisproportionated Bi ions on the two inequivalent sites. The broadening of the\nresonance indicates that local distortions of crystal structure exist in both\ncompounds. The point charge model was used to analyse the electric field\ngradient on the Ba sites",
        "positive": "Photoresponse in large area multi-walled carbon nanotube/polymer\n  nanocomposite films: We present a near IR photoresponse study of large area multi-walled carbon\nnanotube/poly(3-hexylthiophene)-block-polystyrene polymer (MWNT/P3HT-b-PS)\nnanocomposite films for different loading ratio of MWNT into the polymer\nmatrix. We show that the photocurrent strongly depends on the position of the\nlaser spot with maxiumum photocurrent occurring at the metal - film interface.\nIn addition, compared to the pure MWNT film, the photoresponse is much larger\nin the MWNT/polymer composite films. The time constant for the photoresponse is\nslow and varies between 0.6 and 1.2 seconds. We explain the photoresponse by\nSchottky barrier modulation at the metal - film interface."
    },
    {
        "anchor": "Adsorption of gas molecules on graphene nanoribbons and its implication\n  for nano-scale molecule sensor: We have studied the adsorption of gas molecules (CO, NO, NO2, O2, N2, CO2,\nand NH3) on graphene nanoribbons (GNRs) using first principles methods. The\nadsorption geometries, adsorption energies, charge transfer, and electronic\nband structures are obtained. We find that the electronic and transport\nproperties of the GNR with armchair-shaped edges are sensitive to the\nadsorption of NH3 and the system exhibits n type semiconducting behavior after\nNH3 adsorption. Other gas molecules have little effect on modifying the\nconductance of GNRs. Quantum transport calculations further indicate that NH3\nmolecules can be detected out of these gas molecules by GNR based sensor.",
        "positive": "Fully spin-polarized double-Weyl fermions with type-III dispersion in\n  quasi-one dimensional materials X2RhF6 (X=K, Rb, Cs): Double-Weyl fermions, as novel topological states of matter, have been mostly\ndiscussed in nonmagnetic materials. Here, based on density-functional theory\nand symmetry analysis, we propose the realization of fully spin-polarized\ndouble-Weyl fermions in a family ferromagnetic materials X2RhF6 (X= K, Rb, Cs).\nThese materials have the half-metal ground states, where only the bands from\nthe spin-down channel present near the Fermi energy. The spin-down bands form a\npair of triply degenerate nodal points (TDNPs) if spin-orbit coupling (SOC) is\nnot included. Under SOC, one TDNP splits into two double-Weyl points featuring\nquadratic dispersion along two momentum direction, and they are protected by\nthe three-fold rotation (C3) symmetry. Unlike most double-Weyl semimetals, the\nWeyl points proposed here have the type-III dispersion with one of the crossing\nbands being saddle-shaped. An effective model is constructed, which describes\nwell the nature of the Weyl points. These Weyl points are fully spin-polarized,\nand are characterized with double Fermi arcs on the surface spectrum. Breaking\nC3 symmetry by lattice strain could shift one double-Weyl point into a pair of\ntype-II single-Weyl points. The X2RhF6 materials proposed here are excellent\ncandidates to investigate the novel properties of type-III double-Weyl fermions\nin ferromagnetic system, as well as generate potential applications in\nspintronics."
    },
    {
        "anchor": "Strategies for the Construction of Machine-Learning Potentials for\n  Accurate and Efficient Atomic-Scale Simulations: Recent advances in machine-learning interatomic potentials have enabled the\nefficient modeling of complex atomistic systems with an accuracy that is\ncomparable to that of conventional quantum mechanics based methods. At the same\ntime, the construction of new machine-learning potentials can seem a daunting\ntask, as it involves data-science techniques that are not yet common in\nchemistry and materials science. Here, we provide a tutorial-style overview of\nstrategies and best practices for the construction of artificial neural network\n(ANN) potentials. We illustrate the most important aspects of (i) data\ncollection, (ii) model selection, (iii) training and validation, and (iv)\ntesting and refinement of ANN potentials on the basis of practical examples.\nCurrent research in the areas of active learning and delta learning are also\ndiscussed in the context of ANN potentials. This tutorial review aims at\nequipping computational chemists and materials scientists with the required\nbackground knowledge for ANN potential construction and application, with the\nintention to accelerate the adoption of the method, so that it can facilitate\nexciting research that would otherwise be challenging with conventional\nstrategies.",
        "positive": "Correlation between Organic Magnetoresistance (OMAR) and Ferromagnetic\n  ordering: We report observation of ferromagnetic (FM) ordering in organic\nsemiconductors, namely regio-regular poly (3-hexyl thiophene) (RRP3HT) and\n1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-methanofullerene (PCBM), in the\ntemperature range of 5-300 K in addition to magnetoresistance (OMAR) observed\nin the diodes made from the same materials. Particle induced x-ray emission\nspectroscopy confirms the presence of dilute magnetic impurities in the\nmaterials mainly as residues from the synthesis process. However, upon blending\nthese two materials with FM signal, the FM ordering is suppressed by a huge\nparamagnetic (PM) signal indicating ground state charge transfer formation in\nthe blend. Together with the magneto-transport studies, these results indicate\nthat OMAR response is observed in a device only when the corresponding active\nmaterials are FM. In the diodes with P3HT:PCBM complex, that as a blend shows\nPM response, OMAR vanishes almost completely. We propose that ferromagnetism in\nthe active material can have important correlation with the OMAR response in\nthe diodes."
    },
    {
        "anchor": "Thermal Contrast in Nanoscale Infrared Spectroscopy (AFM-IR): Low\n  Frequency Limit: The contrast formation mechanism in Nanoscale Infrared Spectroscopy (Nano-IR\nor AFM-IR) is analyzed for the boundary between two layers with different light\nabsorption, thermal and elastic parameters. Analytical results derived in the\ndecoupling approximation for low frequency limit show that the response\namplitude is linearly proportional to the intensity of the illuminating light\nand thermal expansion coefficient. The spatial resolution between two\ndissimilar materials is linearly proportional to the sum of inverse light\nadsorption coefficients and to the effective thermal transfer length. The\ndifference of displacements height across the T-shape boundary (\"thermo-elastic\nstep\") is proportional to the difference of the adsorption coefficients and\ninversely proportional to the heat transfer coefficient. The step height\nbecomes thickness-independent for thick films and proportional to h^2 in a very\nthin film",
        "positive": "Role of Ionized Impurity and Interface Roughness Scatterings in the\n  Electronic Transport of InAs/GaSb Type II Superlattices at Low Temperatures: The in-plane electron mobility has been calculated in InAs/GaSb type-II\nsuperlattices at low temperatures. The interface roughness scattering and\nionized impurity scattering are investigated as the dominant scattering\nmechanisms in limiting the electron transport at low temperatures. For this\npurpose, the band structures and wave functions of electrons in such\nsuperlattices are calculated by solving the K.P Hamiltonian using the numerical\nFinite Difference method. The scattering rates have obtained for different\ntemperatures and structural parameters. We show that the scattering rates are\nhigh in thin-layer superlattices and the mobility rises as the temperature\nincreases in low-temperature regime."
    },
    {
        "anchor": "New iron-based multiferroics with improper ferroelectricity: In this contribution to the special issue on magnetoelectrics and their\napplications, we focus on some single phase multiferroics theoretically\npredicted and/or experimentally discovered by the authors in recent years. In\nthese materials, iron is the common core element. However, these materials are\nconceptually different from the mostly-studied BiFeO$_3$, since their\nferroelectricity is improper. Our reviewed materials are not simply repeating\none magnetoelectric mechanism, but cover multiple branches of improper\nferroelectricity, including the magnetism-driven ferroelectrics, geometric\nferroelectric, as well as electronic ferroelectric driven by charge ordering.\nIn this sense, these iron-based improper ferroelectrics can be an encyclopaedic\nplayground to explore the comprehensive physics of multiferroics and\nmagnetoelectricity. Furthermore, the unique characteristics of iron's $3d$\norbitals make some of their magnetoelectric properties quite prominent,\ncomparing with the extensively-studied Mn-based improper multiferroics. In\naddition, these materials establish the crossover between multiferroics and\nother fields of functional materials, which enlarges the application scope of\nmultiferroics.",
        "positive": "Impact ionization fronts in Si diodes: Numerical evidence of superfast\n  propagation due to nonlocalized preionization: We present numerical evidence of a novel propagation mode for superfast\nimpact ionization fronts in high-voltage Si $p^+$-$n$-$n^+$ structures. In\nnonlinear dynamics terms, this mode corresponds to a pulled front propagating\ninto an unstable state in the regime of nonlocalized initial conditions. Before\nthe front starts to travel, field-ehanced emission of electrons from deep-level\nimpurities preionizes initially depleted $n$ base creating spatially nonuniform\nfree carriers profile. Impact ionization takes place in the whole high-field\nregion. We find two ionizing fronts that propagate in opposite directions with\nvelocities up to 10 times higher than the saturated drift velocity."
    },
    {
        "anchor": "Krypton oxides under pressure: Under high pressure, krypton, one of the most inert elements is predicted to\nbecome sufficiently reactive to form a new class of krypton compounds; krypton\noxides. Using modern ab-initio evolutionary algorithms in combination with\nDensity Functional Theory, we predict the existence of several\nthermodynamically stable Kr/O species at elevated pressures. In particular, our\ncalculations indicate that at approx. 300 GPa the monoxide, KrO, should form\nspontaneously and remain thermo- and dynamically stable with respect to\nconstituent elements and higher oxides. The monoxide is predicted to form\nnon-molecular crystals with short Kr-O contacts, typical for genuine chemical\nbonds.",
        "positive": "Screening in 2D: GW calculations for surfaces and thin films using the\n  repeated-slab approach: In the context of photoelectron spectroscopy, the $GW$ approach has developed\ninto the method of choice for computing excitation spectra of weakly correlated\nbulk systems and their surfaces. To employ the established computational\nschemes that have been developed for three-dimensional crystals,\ntwo-dimensional systems are typically treated in the repeated-slab approach. In\nthis work we critically examine this approach and identify three important\naspects for which the treatment of long-range screening in two dimensions\ndiffers from the bulk: (1) anisotropy of the macroscopic screening (2) $\\mathbf\nk$-point sampling parallel to the surface (3) periodic repetition and slab-slab\ninteraction. For prototypical semiconductor (silicon) and ionic (NaCl) thin\nfilms we quantify the individual contributions of points (1) to (3) and develop\nrobust and efficient correction schemes derived from the classic theory of\ndielectric screening."
    },
    {
        "anchor": "Unfolding first-principles band structures: A general method is presented to unfold band structures of first-principles\nsuper-cell calculations with proper spectral weight, allowing easier\nvisualization of the electronic structure and the degree of broken\ntranslational symmetry. The resulting unfolded band structures contain\nadditional rich information from the Kohn-Sham orbitals, and absorb the\nstructure factor that makes them ideal for a direct comparison with angular\nresolved photoemission spectroscopy experiments. With negligible computational\nexpense via the use of Wannier functions, this simple method has great\npractical value in the studies of a wide range of materials containing\nimpurities, vacancies, lattice distortions, or spontaneous long-range orders.",
        "positive": "Anti-symmetric Compton scattering in LiNiPO$_4$: Towards a direct probe\n  of the magneto-electric multipole moment: We present a combined theoretical and experimental investigation of the\nanti-symmetric Compton profile in LiNiPO$_4$ as a possible probe for\nmagneto-electric toroidal moments. Understanding as well as detecting such\nmagneto-electric multipoles is an active area of research in condensed matter\nphysics. Our calculations, based on density functional theory, indicate an\nanti-symmetric Compton profile in the direction of the $t_y$ toroidal moment in\nmomentum space, with the computed anti-symmetric profile around four orders of\nmagnitude smaller than the total profile. The difference signal that we measure\nis consistent with the computed profile, but of the same order of magnitude as\nthe statistical errors and systematic uncertainties of the experiment. Our\nresults motivate further theoretical work to understand the factors that\ninfluence the size of the anti-symmetric Compton profile, and to identify\nmaterials exhibiting larger effects."
    },
    {
        "anchor": "Computationally efficient phase-field studies combining simulation\n  sampling and statistical analysis: The trade-off between accuracy and computational cost as a function of the\nsize and number of simulation boxes was studied for large-scale phase-field\nsimulations. For this purpose, a reference simulation box was incrementally\npartitioned. We have considered diffusion-controlled precipitation of delta\nprime in a model Al-Li system from the growth stage until early ripening. The\nresults of the simulations show that decomposition of simulation box can be a\nvaluable computational technique to accelerate simulations without substantial\nloss of accuracy. In the current case study, the precipitate density was found\nto be the key controlling parameter. For a pre-set accuracy, it turned out that\nlarge-scale simulations of the reference domain can be replaced by a\ncombination of smaller simulations. This shortens the required simulation time\nand improves the memory usage of the simulation considerably, and thus\nsubstantially increases the efficiency of massive parallel computation for\nphase-field applications.",
        "positive": "Ab initio prediction of ferrimagnetism, exchange interactions and Curie\n  temperatures in Mn2TiZ Heusler compounds: The Heusler compounds Mn$_2$TiZ (Z = Al, Ga, In, Si, Ge, Sn, P, As, Sb) are\nof large interest due to their potential ferrimagnetic properties and high spin\npolarization. Here, we present calculations of the structural and magnetic\nproperties of these materials. Their magnetic moment follows the Slater-Pauling\nrule $m = N_V - 24$. None of them is actually a perfect half-metallic\nferrimagnet, but some exhibit more than 90% spin polarization and Curie\ntemperatures well above room temperature. The exchange interactions are\ncomplex, direct and indirect exchange contributions are identified. The Curie\ntemperature scales with the total magnetic moment, and it has a positive\npressure dependence. The role of the Z element is investigated: it influences\nthe properties of the compounds mainly via its valence electron number and its\natomic radius, which determines the lattice parameter. Based on these results,\nMn$_2$TiSi, Mn$_2$TiGe, and Mn$_2$TiSn are proposed as candidates for\nspintronic applications."
    },
    {
        "anchor": "Distinct domain-wall motion between creep and flow regimes near the\n  angular momentum compensation temperature of ferrimagnet: We investigate a magnetic domain-wall (DW) motion in two dynamic regimes,\ncreep and flow regimes, near the angular momentum compensation temperature\n(T_A) of ferrimagnet. In the flow regime, the DW speed shows sharp increase at\nT_A due to the emergence of antiferromagnetic DW dynamics. In the creep regime,\nhowever, the DW speed exhibits a monotonic increase with increasing the\ntemperature. This result suggests that, in the creep regime, the thermal\nactivation process governs the DW dynamics even near T_A. Our result\nunambiguously shows the distinct behavior of ferrimagnetic DW motion depending\non the dynamic regime, which is important for emerging ferrimagnet-based\nspintronic applications.",
        "positive": "Supramolecular Stacking of Doxorubicin on Carbon Nanotubes for in vivo\n  Cancer Therapy: Many therapeutic advantages such as prolonged circulation in the blood,\nincreased tumor drug uptake, enhanced therapeutic efficacy, and markedly\nreduced toxic side effects are provided by a carbon nanotube based\nchemotherapeutic formulation. In this system, doxorubicin (DOX) is loaded onto\nthe sidewalls of functionalized single-walled carbon nanotubes by\nsupramolecular pi-pi stacking."
    },
    {
        "anchor": "High-Entropy Oxides Based on Valence Combinations: Design and Practice: High-entropy oxides (HEOs) are a new class of materials that are promising\nfor a wide range of applications. Designing HEOs needs to consider both\ngeometric compatibility and electrical equilibrium. However, there is currently\nno available method to systematically consider these two factors when selecting\nconstituent materials for making HEOs. Here we propose a two-step strategy,\nwhere a HEO system to be explored is first partitioned into multiple subsystems\nbased on the valence combinations of substituted cations; the geometric\ncompatibility is then considered in selecting suitable substituted cations. We\ndemonstrate this strategy by using A(5B0.2)O3 perovskite as a model system. We\nshow that the system can be partitioned into 12 subsystems. Ten of the\nsubsystems have formed a single-phase cubic perovskite, while two have\npartially ordering structure. The formation of single phases is correlated to\nGoldschmidt's tolerance factor, while the formation of the ordering structure\nis mainly correlated to cation-valence difference. We anticipate that this\nstrategy is applicable to exploring HEOs in other systems.",
        "positive": "Eulerian conjugate stress and strain: New results are presented for the stress conjugate to arbitrary Eulerian\nstrain measures. The conjugate stress depends on two arbitrary quantities: the\nstrain measure f(V) and the corotational rate defined by the spin \\Omega. It is\nshown that for every choice of f there is a unique spin, called the f-spin,\nwhich makes the conjugate stress as close as possible to the Cauchy stress. The\nf-spin reduces to the logarithmic spin when the strain measure is the Hencky\nstrain log(V). The formulation and the results emphasize the similarities in\nform of the Eulerian and Lagrangian stresses conjugate to the strains f(V) and\nf(U), respectively. Many of the results involve the solution to the equation\nAX-XA=Y, which is presented in a succinct format."
    },
    {
        "anchor": "Atomistic Field Theory for contact electrification of dielectrics: The triboelectrification of conducting materials can be explained by electron\ntransfer between different Fermi levels. However, triboelectrification in\ndielectrics is poorly understood. The surface dipole formations are shown to be\ncaused by the contact-induced surface lattice deformations. An Atomistic Field\nTheory (AFT) based formulation is utilized to calculate the distribution of the\npolarization, electric and potential fields. The induced fields are considered\nas the driving force for charge transfer. The simulation results show that a\nMgO/BaTiO3 tribopair can generate up to 104 V/cm^2, which is comprable with the\ndata in the published literature.",
        "positive": "Magneto-optic Response of the Metallic Antiferromagnet Fe$_{2}$As to\n  Ultrafast Temperature Excursions: The linear magneto-optical Kerr effect (MOKE) is often used to probe\nmagnetism of ferromagnetic materials, but MOKE cannot be applied to collinear\nantiferromagnets (AFs) due to the cancellation of sub-lattice magnetization.\nMagneto-optical constants that are quadratic in magnetization, however, provide\nan approach for studying AFs on picosecond time scales. Here, we combine\ntransient measurements of optical reflectivity and birefringence to study the\nlinear optical response of Fe$_{2}$As to small ultrafast temperature\nexcursions. We performed temperature dependent pump-probe measurements on\ncrystallographically isotropic (001) and anisotropic (010) faces of Fe$_{2}$As\nbulk crystals. We find the largest optical signals arise from changes in the\nindex of refraction along the $z$-axis, i.e. perpendicular to the N\\'eel\nvector. Both real and imaginary parts of the time-resolved optical\nbirefringence rotation signal approximately follow the temperature dependence\nof the magnetic heat capacity, as expected if the changes in dielectric\nconstants are dominated by contributions of exchange interactions to the\ndielectric constant. We conclude that under our experimental conditions,\nchanges in the exchange interaction contribute more strongly to the temperature\ndependence of the magneto-optic constants than the Voigt effect."
    },
    {
        "anchor": "First-Principle Study of Dislocation Slips in Impurity Doped Graphene: Employing density-functional theory (DFT) calculations, the\ngeneralized-stacking-fault energy (GSFE) curves along two crystallographic\nslips, glide and shuffle, for both pristine graphene and impurity of boron (B)\nor nitrogen (N) doped graphene were examined. The effects of B and N doping on\nthe GSFE were clarified and correlated with local electron interactions and\nbonding configurations. The GSFE data were then used to analyze dislocation\ndipole and core structure, and subsequently combined with the Peierls-Nabarro\n(P-N) model to examine the role of doping on several key characteristics of\ndislocations in graphene. We showed that the GSFE curve may be significantly\naltered by the presence of dopants, which subsequently leads to profound\nmodulations of dislocation properties, such as increasing spontaneous\npair-annihilation distance and reducing resistance to dislocation slip. Our\nresults indicate that doping can play an important role in controlling\ndislocation density and microscopic plasticity in graphene, thereby providing\ncritical insights for dopant-mediated defect engineering in graphene.",
        "positive": "Resonant soft X-ray scattering reveals hierarchical structure in a\n  multi-component vapor-deposited glass: Multi-phase vapor-deposited glasses are an important class of materials for\norganic electronics, particularly organic photovoltaics and thermoelectrics.\nThese blends are frequently regarded as molecular alloys and there have been\nfew studies of their structure at nanometer scales. Here we show that a\nco-deposited system of TPD and Disperse Orange 37, two small molecule\nglass-formers, separates into compositionally distinct phases with a domain\nsize and spacing that depends on substrate temperature during deposition.\nDomains rich in one of the two components become larger and more pure at higher\ndeposition temperatures. We use resonant soft X-ray scattering (RSoXS)\ncomplemented with Atomic Force Microscopy (AFM) and photo-induced force\nmicroscopy (PiFM) to measure the phase separation, topography, and purity of\nthe deposited films. A forward-simulation approach to RSoXS analysis, the\nNational Institute of Standards and Technology (NIST) RSoXS Simulation Suite\n(NRSS), is used with models developed from AFM images to evaluate the energy\ndependence of scattering across multiple length scales and interpret the RSoXS\nwith respect to structure within the films. We find that the RSoXS is sensitive\nto a hidden length scale of phase separation that is not apparent from the AFM\ncharacterization alone. We demonstrate that vacuum scattering, which is often\nignored in RSoXS analysis, contributes significantly to the features and energy\ndependence of the RSoXS pattern, and then illustrate how to properly account\nfor vacuum scattering to analyze films with significant roughness. We then use\nthis analysis framework to understand structure development mechanisms that\noccur during vapor deposition of a TPD-DO37 co-deposited glass with results\nthat outline paths to tune morphology in multi-component materials."
    },
    {
        "anchor": "Thermal conductivity of h-BN monolayers using machine learning\n  interatomic potential: Thermal management materials are of critical importance for engineering\nminiaturized electronic devices, where theoretical design of such materials\ndemands the evaluation of thermal conductivities which are numerically\nexpensive. In this work, we applied the recently developed machine learning\ninteratomic potential (MLIP) to evaluate the thermal conductivity of hexagonal\nboron nitride monolayers. The MLIP is obtained using the Gaussian approximation\npotential (GAP) method, and the resulting lattice dynamical properties and\nthermal conductivity are compared with those obtained from explicit frozen\nphonon calculations. It is observed that accurate thermal conductivity can be\nobtained based on MLIP constructed with about 30% representative\nconfigurations, and the high-order force constants provide a more reliable\nbenchmark on the quality of MLIP than the harmonic approximation.",
        "positive": "Hyperfine local probe study of alkaline-earth manganites SrMnO3 and\n  BaMnO3: We report perturbed angular correlation measurements with 111mCd/111Cd and\n111In/111Cd probes, at the ISOLDE-CERN facility, in the manganite compounds\nBaMnO3 , with the 6H and 15R polymorphs, and SrMnO3 , with the 4H polymorph.\nThe electric field gradient (EFG) is measured, and found approximately constant\nin a large temperature range for all the compounds. The EFG is also calculated\nfrom first principles with density functional theory, and compared with\nexperimental results by considering diluted substitutional Cd impurities. Based\non the results, we assign as sites for the probes the Ba (for BaMnO3-6H, 15R)\nand Sr (for SrMnO3-4H) sites, apart from fractions of undetermined origin in\nthe case of BaMnO3-6H. We predict the hyperfine parameters in the recently\nsynthesized multiferroic manganite Sr0.5Ba0.5MnO3 , and its variation with the\nstructure and electric polarization, which is found to be very small."
    },
    {
        "anchor": "Hardness of T-carbon: Density functional theory calculations: We revisit and interpret the mechanical properties of the recently proposed\nallotrope of carbon, T-carbon [Sheng \\emph{et al.}, Phys. Rev. Lett.,\n\\textbf{106}, 155703 (2011)], using density functional theory in combination\nwith different empirical hardness models. In contrast with the early estimation\nbased on the Gao's model, which attributes to T-carbon an high Vickers hardness\nof 61 GPa comparable to that of superhard cubic boron nitride (\\emph{c}-BN), we\nfind that T-carbon is not a superhard material, since its Vickers hardenss does\nnot exceed 10 GPa. Besides providing clear evidence for the absence of\nsuperhardenss in T-carbon, we discuss the physical reasons behind the failure\nof Gao's and \\v{S}im$\\rm\\mathring{u}$nek and Vack\\'a\\v{r}'s (SV) models in\npredicting the hardness of T-carbon, residing on their improper treatment of\nthe highly anisotropic distribution of quasi-\\emph{sp}$^3$-like C-C hybrids. A\npossible remedy to the Gao and SV models based on the concept of superatom is\nsuggest, which indeed yields a Vickers hardness of about 8 GPa.",
        "positive": "Dynamical and anharmonic effects on the electron-phonon coupling and the\n  zero-point renormalization of the electronic structure: The renormalization of the band structure at zero temperature due to\nelectron-phonon coupling is investigated in diamond, BN, LiF and MgO crystals.\nWe implement a dynamical scheme to compute the frequency-dependent self-energy\nand the resulting quasiparticle electronic structure. Our calculations reveal\nthe presence of a satellite band below the Fermi level of LiF and MgO. We show\nthat the renormalization factor (Z), which is neglected in the adiabatic\napproximation, can reduce the zero-point renormalization (ZPR) by as much as\n40%. Anharmonic effects in the renormalized eigenvalues at finite atomic\ndisplacements are explored with the frozen-phonon method. We use a\nnon-perturbative expression for the ZPR, going beyond the Allen-Heine-Cardona\ntheory. Our results indicate that high-order electron-phonon coupling terms\ncontribute significantly to the zero-point renormalization for certain\nmaterials."
    },
    {
        "anchor": "Predicting Young's Modulus of Glasses with Sparse Datasets using Machine\n  Learning: Machine learning (ML) methods are becoming popular tools for the prediction\nand design of novel materials. In particular, neural network (NN) is a\npromising ML method, which can be used to identify hidden trends in the data.\nHowever, these methods rely on large datasets and often exhibit overfitting\nwhen used with sparse dataset. Further, assessing the uncertainty in\npredictions for a new dataset or an extrapolation of the present dataset is\nchallenging. Herein, using Gaussian process regression (GPR), we predict\nYoung's modulus for silicate glasses having sparse dataset. We show that GPR\nsignificantly outperforms NN for sparse dataset, while ensuring no overfitting.\nFurther, thanks to the nonparametric nature, GPR provides quantitative bounds\nfor the reliability of predictions while extrapolating. Overall, GPR presents\nan advanced ML methodology for accelerating the development of novel functional\nmaterials such as glasses.",
        "positive": "Electronic structure and magnetism in two-dimensional hexagonal 5d\n  transition metal carbides, Tan+1Cn (n=1,2,3): Density functional calculations are used to investigate the electronic\nstructure of two-dimensional 5d tantalum carbides with honeycomb-like lattice\nstructures. We focus on changes in the low-energy bands near the Fermi level\nwith dimensionality. We find that the Ta 5d states dominate, but the extended\nnature of the wavefunctions makes them weakly correlated. The carbide sheets\nare prone to long range magnetic order. We evaluate the stability of these\nstates to enhanced electron--electron interactions through a Hubbard U\ncorrection. Lastly, we find spin orbit interactions strongly renormalize the\nband structure for n=2, but play a minor role in n=1 and 3."
    },
    {
        "anchor": "Microwave spectroscopy of the low-temperature skyrmion state in Cu2OSeO3: In the cubic chiral magnet Cu2OSeO3 a low-temperature skyrmion state (LTS)\nand a concomitant tilted conical state are observed for magnetic fields\nparallel to <100>. In this work, we report on the dynamic resonances of these\nnovel magnetic states. After promoting the nucleation of the LTS by means of\nfield cycling, we apply broadband microwave spectroscopy in two experimental\ngeometries that provide either predominantly in-plane or out-of-plane\nexcitation. By comparing the results to linear spin-wave theory, we clearly\nidentify resonant modes associated with the tilted conical state, the\ngyrational and breathing modes associated with the LTS, as well as the\nhybridization of the breathing mode with a dark octupole gyration mode mediated\nby the magnetocrystalline anisotropies. Most intriguingly, our findings suggest\nthat under decreasing fields the hexagonal skyrmion lattice becomes unstable\nwith respect to an oblique deformation, reflected in the formation of elongated\nskyrmions.",
        "positive": "Microscopic model for the ferroelectric field effect in oxide\n  heterostructures: A microscopic model Hamiltonian for the ferroelectric field effect is\nintroduced for the study of oxide heterostructures with ferroelectric\ncomponents. The long-range Coulomb interaction is incorporated as an\nelectrostatic potential, solved self-consistently together with the charge\ndistribution. A generic double-exchange system is used as the conducting\nchannel, epitaxially attached to the ferroelectric gate. The observed\nferroelectric screening effect, namely the charge accumulation/depletion near\nthe interface, is shown to drive interfacial phase transitions that give rise\nto robust magnetoelectric responses and bipolar resistive switching, in\nqualitative agreement with previous density functional theory calculations. The\nmodel can be easily adapted to other materials by modifying the Hamiltonian of\nthe conducting channel, and it is useful in simulating ferroelectric field\neffect devices particularly those involving strongly correlated electronic\ncomponents where ab-initio techniques are difficult to apply."
    },
    {
        "anchor": "Creep and flow regimes of magnetic domain wall motion in ultrathin\n  Pt/Co/Pt films with perpendicular anisotropy: We report on magnetic domain wall velocity measurements in ultrathin\nPt/Co(0.5-0.8 nm)/Pt films with perpendicular anisotropy over a large range of\napplied magnetic fields. The complete velocity-field characteristics are\nobtained, enabling an examination of the transition between thermally activated\ncreep and viscous flow: motion regimes predicted from general theories for\ndriven elastic interfaces in weakly disordered media. The dissipation limited\nflow regime is found to be consistent with precessional domain wall motion,\nanalysis of which yields values for the damping parameter, $\\alpha$.",
        "positive": "Formation of ripple pattern on silicon surface by grazing incidence ion\n  beam sputtering: Off-normal low energy ion beam sputtering of solid surfaces often leads to\nmorphological instabilities resulting in the spontaneous formation of ripple\nstructures in nanometer length scales. In the case of Si surfaces at ambient\ntemperature, ripple formation is found to take place normally at lower incident\nangles with the wave vector parallel to the ion beam direction. The absence of\nripple pattern on Si surface at larger angles is due to the dominance of ion\nbeam polishing effect. We have shown that a gentle chemical roughening of the\nstarting surface morphology can initiate ripple pattern under grazing incidence\nion beam sputtering, where the ripple wave vector is perpendicular to the ion\nbeam direction. The characteristics of the perpendicular mode ripples are\nstudied as a function of pristine surface roughness and ion fluence. The\nquality of the morphological structure is assessed from the analysis of ion\ninduced topological defects."
    },
    {
        "anchor": "Some features of the transport processes of ion-implanted boron under\n  conditions of transient enhanced diffusion suppression: It has been shown that during thermal treatments of silicon layers\npreamorphized by germanium implantation and then implanted with boron ions the\ntransport of impurity atoms occurs right up to a temperature of 850^{\\circ}C\ndue to migration of the nonequilibrium boron interstitials.",
        "positive": "Nonlinear spin Hall effect in GaAs (110) quantum wells: We consider stationary spin current in a (110)-oriented GaAs-based symmetric\nquantum well due to a nonlinear response to an external periodic electric\nfield. The model assumed includes the Dresselhaus spin-orbit interaction and\nthe random Rashba spin-orbit coupling. The Dresselhaus term is uniform in the\nquantum well plane and gives rise to spin splitting of the electron band. The\nexternal electric field of frequency $\\omega$ - in the presence of random\nRashba coupling -- leads to virtual spin-flip transitions between spin\nsubbands, generating stationary pure spin current proportional to the square of\nthe field amplitude."
    },
    {
        "anchor": "Structure and superconductivity of Mg(B1-xCx)2 compounds: In this paper, we reported the structural properties and superconductivity of\nMg(B1-xCx)2 compounds. Powder x-ray diffraction results indicate that the\nsamples crystallize in a hexagonal AlB2-type structure. Due to the chemical\nactivity of Mg powders, a small amount of MgO impurity phase was detected by\nx-ray diffraction. The lattice parameters decrease slightly with increasing\ncarbon content. Magnetization measurements indicate the non-stoichiometry of\nMgB2 has no influence on the superconducting transition temperature and the\ntransition temperature width. The addition of carbon results in a decrease of\nTc and an increase in the superconducting transition width, implying the loss\nof superconductivity.",
        "positive": "Phonons and Lithium diffusion in LiAlO$_2$: We report on investigations of phonons and lithium diffusion in LiAlO$_2$\nbased on inelastic neutron scattering (INS) measurements of the phonon density\nof states (DOS) in {\\gamma}-LiAlO$_2$ from 473 K to 1073 K, complemented with\nab-initio molecular dynamics (AIMD) simulations. We find that phonon modes\nrelated to Li vibrations broaden on warming as reflected in the measured phonon\nDOS and reproduced in simulations. Further, the AIMD simulations probe the\nnature of lithium diffusion in the perfect crystalline phase\n({\\gamma}-LiAlO$_2$), as well as in a structure with lithium vacancies and a\nrelated amorphous phase. Almost liquid-like super-ionic diffusion is observed\nin AIMD simulations of the three structures at high temperatures; with\npredicted onset temperatures of 1800 K, 1200 K, and 600 K in the perfect\nstructure, vacancy structure and the amorphous phase, respectively. In the\nideal structure, the Li atoms show correlated jumps; while simple and\ncorrelated jumps are both seen in the vacancy structure, and a mix of jumps and\ncontinuous diffusion occur in the amorphous structure. Further, we find that\nthe Li-diffusion is favored in all cases by a large librational amplitude of\nthe neighbouring AlO4 tetrahedra, and that the amorphous structure opens\nadditional diffusion pathways due to a broad distribution of AlO4 tetrahedra\norientations."
    },
    {
        "anchor": "On the interplay between electrical conductivity and Seebeck coefficient\n  in ultra-narrow silicon nanowires: We analyze the effect of low dimensionality on the electrical conductivity\n({\\sigma}) and Seebeck coefficient (S) in ultra-narrow Si nanowires (NWs) by\nemploying atomistic considerations for the electronic structures and linearized\nBoltzmann transport theory. We show that changes in the geometrical features of\nthe NWs such as diameter and orientation, mostly affect {\\sigma} and S in two\nways: i) the distance of the band edges from the Fermi level ({\\eta}F) changes,\nand ii) quantum confinement in some cases strongly affect the effective mass of\nthe subbands, which influences the conductivity of the NWs and {\\eta}F. Changes\nin eta_F cause exponential changes in {\\sigma}, but linear changes in S. S\nseems to be only weakly dependent on the curvature of the bands, the strength\nof the scattering mechanisms, and the shape of the DOS(E) function, contrary to\ncurrent view. Our results indicate that low dimensionality has a stronger\ninfluence on {\\sigma} than on S due to the stronger sensitivity of {\\sigma} on\n{\\eta}F. We identify cases where bandstructure engineering through confinement\ncan improve {\\sigma} without significantly affecting S, which can result in\npower factor improvements.",
        "positive": "Excitons in two-dimensional materials: Because of the reduced dielectric screening and enhanced Coulomb\ninteractions, two-dimensional (2D) materials like phosphorene and transition\nmetal dichalcogenides (TMDs) exhibit strong excitonic effects, resulting in\nfascinating many-particle phenomena covering both intralayer and interlayer\nexcitons. Their intrinsic bandgaps and strong excitonic emissions allow the\npossibility to tune the inherent optical, electrical, and optoelectronic\nproperties of 2D materials via a variety of external stimuli, making them\npotential candidates for novel optoelectronic applications. In this review, we\nsummarize exciton physics and devices in 2D semiconductors and insulators,\nespecially in phosphorene, TMDs, and their van der Waals heterostructures\n(vdWHs). In the first part, we discuss the remarkably versatile excitonic\nlandscape, including bright and dark excitons, trions, biexcitons, and\ninterlayer excitons. In the second part, we examine common control methods to\ntune excitonic effects via electrical, magnetic, optical, and mechanical means.\nIn the next stage, we provide recent advances on the optoelectronic device\napplications, such as electroluminescent devices, photovoltaic solar cells, and\nphotodetectors. We conclude with a brief discussion on their potential to\nexploit vdWHs towards unique exciton physics and devices."
    },
    {
        "anchor": "Accuracy of generalized gradient approximation functionals for density\n  functional perturbation theory calculations: We assess the validity of various exchange-correlation functionals for\ncomputing the structural, vibrational, dielectric, and thermodynamical\nproperties of materials in the framework of density-functional perturbation\ntheory (DFPT). We consider five generalized-gradient approximation (GGA)\nfunctionals (PBE, PBEsol, WC, AM05, and HTBS) as well as the local density\napproximation (LDA) functional. We investigate a wide variety of materials\nincluding a semiconductor (silicon), a metal (copper), and various insulators\n(SiO$_2$ $\\alpha$-quartz and stishovite, ZrSiO$_4$ zircon, and MgO periclase).\nFor the structural properties, we find that PBEsol and WC are the closest to\nthe experiments and AM05 performs only slightly worse. All three functionals\nactually improve over LDA and PBE in contrast with HTBS, which is shown to fail\ndramatically for $\\alpha$-quartz. For the vibrational and thermodynamical\nproperties, LDA performs surprisingly very good. In the majority of the test\ncases, it outperforms PBE significantly and also the WC, PBEsol and AM05\nfunctionals though by a smaller margin (and to the detriment of structural\nparameters). On the other hand, HTBS performs also poorly for vibrational\nquantities. For the dielectric properties, none of the functionals can be put\nforward. They all (i) fail to reproduce the electronic dielectric constant due\nto the well-known band gap problem and (ii) tend to overestimate the oscillator\nstrengths (and hence the static dielectric constant).",
        "positive": "Dual phase patterning during a congruent grain boundary phase transition\n  in elemental copper: The phase behavior of grain boundaries can have a strong influence on\ninterfacial properties. Little is known about the emergence of grain boundary\nphases in elemental metal systems and how they transform. Here, we observe the\nnanoscale patterning of a grain boundary by two alternating grain boundary\nphases with distinct atomic structures in elemental copper by atomic resolution\nimaging. The same grain boundary phases are found by grain boundary structure\nsearch indicating a first-order transformation. Finite temperature atomistic\nsimulations reveal a congruent, diffusionless transition between these phases\nunder ambient pressure. The patterning of the grain boundary at room\ntemperature is dominated by the grain boundary phase junctions separating the\nphase segments. Our analysis suggests that the reduced mobility of the phase\njunctions at low temperatures kinetically limits the transformation, but\nrepulsive elastic interactions between them and disconnections could\nadditionally stabilize the pattern formation."
    },
    {
        "anchor": "Towards reducing tension-compression yield and cyclic asymmetry in pure\n  magnesium and magnesium-aluminum alloy with cerium addition: In this study, we report the effect of cerium (Ce) addition on the\ntension-compression yield and cyclic asymmetry in commercially pure magnesium\n(Cp-Mg) and Mg-Al alloy at room temperature (RT). The investigated materials\nCp-Mg, Mg-0.5Ce, and Mg-3Al-0.5Ce were extruded at 400{\\deg}C, followed by\nannealing at the same temperature for one hour. Incorporating 0.5wt.% Ce in\npure Mg results in the weakening of its basal texture, uniform distribution of\nMg12Ce precipitates, and grain size refinement. Consequently, the tensile yield\nstrength and ductility of pure Mg increased, and tension-compression yield\nasymmetry was eliminated. However, the presence of 3wt.% Al in Mg suppresses\nthe beneficial effects of Ce addition. The formation of complex precipitates,\nsuch as Mg-Al-Ce and Al11Ce3, limits the weakening of the basal texture,\nreduction in grain size, improvement in ductility, and elimination of\ntension-compression yield asymmetry observed in Mg-0.5Ce. Nevertheless, Al\ncontributes to the solid solution strengthening in Mg and possibly lowers the\ncritical stress required for twinning in Mg, resulting in the highest tensile\nstrength of Mg-3Al-0.5Ce. Finally, the addition of 0.5wt.% Ce enhances the\ncyclic strength, stabilizes cyclic stress response, reduces inelastic strain,\nand minimizes cyclic asymmetry in both pure Mg and Mg-Al alloy while\nmaintaining a comparable fatigue life. Overall, Ce addition positively impacts\nthe microstructure and mechanical behavior of pure Mg and its investigated\nalloy. The reasons for these improvements are discussed in detail.",
        "positive": "Formation of Collapsed Tetragonal Phase in EuCo2As2 under High Pressure: The structural properties of EuCo2As2 have been studied up to 35 GPa, through\nthe use of x-ray diffraction in a diamond anvil cell at a synchrotron source.\nAt ambient conditions, EuCo2As2 (I4/mmm) has a tetragonal lattice structure\nwith a bulk modulus of 48 +/-4 GPa. With the application of pressure, the\na-axis exhibits negative compressibility with a concurrent sharp decrease in\nc-axis length. The anomalous compressibility of the a-axis continues until 4.7\nGPa, at which point the structure undergoes a second-order phase transition to\na collapsed tetragonal (CT) state with a bulk modulus of 111 +/- 2 GPa. We\nfound a strong correlation between the ambient pressure volume of 122 parents\nof superconductors and the corresponding tetragonal to collapsed tetragonal\nphase transition pressures"
    },
    {
        "anchor": "Controllable Water Vapor Assisted Chemical Vapor Transport Synthesis of\n  WS2-MoS2 Heterostructure: The vapor phase synthesis of two-dimensional transition-metal dichalcogenides\n(MX2) and their heterostructures is often poorly reproducible and sensitive to\nuncontrolled environmental humidity. It was recently realized that water vapor\ncan play important roles in the growth of MX2 by reacting with MX2 at high\ntemperature to form volatile metal oxyhydroxide (MOx(OH)y) and hydrogen\nchalcogenides (H2X) that dramatically change the growth processes. Here we\nreport the controllable synthesis of WS2, MoS2, and their heterostructures\nusing water-assisted chemical vapor transport (CVT). The water vapor can be\ntunably delivered by thermal dehydration of calcium sulfate dihydrate (CaSO4\n2H2O) solid precursor, which not only provides much lower vapor pressure\nbaseline and a wider tunable range than liquid water, but also can be readily\nintegrated into a chemical vapor deposition process. This allows controlled\ngrowth of monolayer, multilayers, and spiral nanoplates of WS2, as well as the\nlateral epitaxial growth on the edge of MX2, and more reproducible growth of\nlarge area WS2-MoS2 heterostructures. Raman and photoluminescence spectral\nmappings confirm the various types of WS2-MoS2 heterostructures. These results\nreveal insights into the growth mechanisms of MX2 and provide a general\napproach to the controllable growth of other metal chalcogenides.",
        "positive": "Synthesis, Structural, Electrical and Microchemistry Properties of Novel\n  (LSCFM) LaxSr1-xCo1-y-zFeyMnzO3-\u03b4 (x=0.4, 0.6, 0.8, y=0.4, 0.8 and\n  z=0.1, 0.2) Perovskites for SOFC Applications: Perovskites are mixed oxides with the general formula ABO3. Many different\ncompositions have been found to be possible and their number is growing rapidly\ndue to their characteristics that make them ideal for various applications,\nsuch as fabrication of cathodes for solid oxide fuel cells (SOFCs). Oxide\npowders of LaxSr1-xCo1-y-zFeyMnzO3-{\\delta} (x=0.4, 0.6, 0.8, y=0.4, 0.8 and\nz=0.1, 0.2), named LSCFM, were prepared by mixing commercial powders. The\npowders have been investigated as a function of the stoichiometry and the\ncrystal structure parameters have been determined using Rietveld analysis. The\nresults of the structural analysis for each sintered sample, at low temperature\nsintering (1100 {\\omicron}C), have been obtained by considering two cubic\nperovskite phases, for x=0.4 or one cubic and one orthorhombic phase for x=0.6,\n0.8, respectively. Analysis of microstructure has shown a maximum grain size of\n~0.63 {\\mu}m. The annealed sample at 1100 {\\omicron}C, an almost single phase\nspecimen, exhibited an electrical conductivity of 1.29\\times103 ({\\Omega} \\cdot\ncm)-1. The sintered sample at 1250 {\\omicron}C has higher conductivity but\nsharper curve close to the maximum. We suggest that low temperature sintering\nreveal two phase system with broader curve maximum and high conductivity for\nfuture applications in SOFCs."
    },
    {
        "anchor": "Decoration of graphene nanoribbons by $5d$ transition-metal elements: Graphene is a famous truly two-dimensional (2D) material, possessing a\ncone-like energy structure near the Fermi level and treated as a gapless\nsemiconductor. Its unique properties trigger researchers to find applications\nof it. The gapless feature shrinks the development of graphene nanoelectronics.\nMaking one-dimensional (1D) strips of graphene nanoribbons (GNRs) could be one\nof the promising routes to modulating the electronic and optical properties of\ngraphene. The electronic and optical properties of GNRs are highly sensitive to\nthe edge and width. The tunability in electronic and optical properties further\nimplies the possibilities of GNR application. However, the dangling bonds at\nribbon edges remain an open question in GNR systems. Various passivation at the\nribbon edge might change the essential physical properties. In this work, $5d$\ntransition-metal elements are considered as the guest atoms at the edges. The\ngeometric structure, energy bands, density of states, charge distribution, and\noptical transitions are discussed.",
        "positive": "Elastic properties of model porous ceramics: The finite element method (FEM) is used to study the influence of porosity\nand pore shape on the elastic properties of model porous ceramics. The Young's\nmodulus of each model was found to be practically independent of the solid\nPoisson's ratio. At a sufficiently high porosity, the Poisson's ratio of the\nporous models converged to a fixed value independent of the solid Poisson's\nratio. The Young's modulus of the models is in good agreement with experimental\ndata. We provide simple formulae which can be used to predict the elastic\nproperties of ceramics, and allow the accurate interpretation of empirical\nproperty-porosity relations in terms of pore shape and structure."
    },
    {
        "anchor": "Phase transformations surfaces and exact energy lower bounds: The paper investigates two-phase microstructures of optimal 3D composites\nthat store minimal elastic energy in a given strain field. The composite is\nmade of two linear isotropic materials which differ in elastic moduli and\nself-strains. We find optimal microstructures for all values of external\nstrains and volume fractions of components. This study continues research by\nGibiansky and Cherkaev\n\\cite{gibiansky1987microstructures,GibianskyCherkaev1997} and Chenchiah and\nBhattacharya \\cite{Bhattacharya2008}. In the present paper we demonstrate that\nthe energy is minimized by that laminates of various ranks. Optimal structures\nare either simple laminates that are codirected with external eigenstrain\ndirections, or inclined laminates, direct and skew second-rank laminates and\nthird-rank laminates. These results are applied for description of direct and\nreverse transformations limit surfaces in a strain space for elastic solids\nundergoing phase transformations of martensite type. The surfaces are computed\nas the values of external strains at which the optimal volume fraction of one\nof the phases tends to zero. Finally, we compare the transformation surfaces\nwith the envelopes of the nucleation surfaces constructed earlier for nuclei of\nvarious geometries (planar layers, elliptical cylinders, ellipsoids). We show\nthe energy equivalence of the cylinders and direct second-rank-laminates,\nellipsoids and third-rank laminates. We note that skew second-rank laminates\nmake the nucleation surface convex function of external strain, and they do not\ncorrespond to any of the mentioned nuclei.",
        "positive": "Enhancement of CO detection in Al doped graphene: A principle of enhancement CO adsorption was developed theoretically by using\ndensity functional theory through doping Al into graphene. The results show\nthat the Al doped graphene has strong chemisorption of CO molecule by forming\nAl-CO bond, where CO onto intrinsic graphene remains weak physisorption.\nFurthermore, the enhancement of CO sensitivity in the Al doped graphene is\ndetermined by a large electrical conductivity change after adsorption, where CO\nabsorption leads to increase of electrical conductivity upon via introducing\nlarge amount of shallow acceptor states. Therefore, this newly developed Al\ndoped graphene would be an excellent candidate for sensing CO gas."
    },
    {
        "anchor": "Laves phase crystal analysis (LaCA): Atomistic identification of lattice\n  defects in C14 and C15 topologically close-packed phases: The identification of defects in crystal structures is crucial for the\nanalysis of atomistic simulations. Many methods to characterize defects that\nare based on the classification of local atomic arrangement are available for\nsimple crystalline structures. However, there is currently no method to\nidentify both, the crystal structures and internal defects of topologically\nclose-packed (TCP) phases such as Laves phases. We propose a new method, Laves\nphase Crystal Analysis (LaCA), to characterize the atomic arrangement in Laves\ncrystals by interweaving existing structural analysis algorithms. The new\nmethod can identify the polytypes C14 and C15 of Laves phases, typical\ncrystallographic defects in these phases, and common deformation mechanisms\nsuch as synchroshear and non-basal dislocations. Defects in the C36 Laves phase\nare detectable through deviations from the periodic arrangement of the C14 and\nC15 structures that make up this phase. LaCA is robust and extendable to other\nTCP phases.",
        "positive": "Chemical Principles of Topological Semimetals: Initiated by the discovery of topological insulators, topologically\nnon-trivial materials have attracted immense interest in the physics community\nin the past decade. One of the latest additions to the field, the material\nclass of topological semimetals, has grown at an extremely fast rate . While\nthe prototype of a topological semimetal, graphene, has been known for a while,\nthe first 3D analogues of graphene have only been discovered recently. This\nreview, written from a chemistry perspective, intends to make the growing field\nof topological semimetals accessible to the wider community of materials\nscientists and scholars from related disciplines. To this end, we describe key\nfeatures of topological semimetals, embedded in their electronic structure, and\nhow they can be achieved based on chemical principles. We introduce the\ndifferent classes of topological semimetals and review their salient\nrepresentatives. Finally, selected properties and potential applications of\nthese materials are discussed."
    },
    {
        "anchor": "A transient thermal cloak experimentally realized through a rescaled\n  diffusion equation with anisotropic thermal diffusivity: Transformation optics originating from the invariance of Maxwell's equations\nunder the coordinate mapping has enabled the design and demonstration of many\nfascinating electromagnetic devices that were unconceivable or deemed\nimpossible before [1-11], and has greatly contributed to the advancement of\nmodern electromagnetism and related researches assisted with the development of\nmetamaterials [12-15]. This technique has been extended to apply to other\npartial differential equations governing different waves [16-23] or flux\n[24-28], and has produced various novel functional devices such as acoustic\ncloaks [20-23] and Schrodinger's 'hat' [19]. In the present work we applied the\ncoordinate transformation to the time-dependent heat diffusion equation [24-28]\nand achieved the manipulation of the heat flux by predefined diffusion paths.\nIn the experiment we demonstrated a transient thermal cloaking device\nengineered with thermal metamaterials and successfully hid a centimeter sized\nstrong 'scatter' (thermal disturber), i.e., a vacuum cavity. To facilitate\nreliable fabrication we adopted the rescaled thermal diffusion equation for\nvarious ingredient materials with nearly constant product of the density and\nheat capacity, and took the anisotropic thermal diffusivities as the key\nparameters for the design. Our results unambiguously show the practical\npossibility to implement the complex transformed thermal media with high\naccuracy and acquire some unprecedented thermodynamic functions, which we\nbelieve will help to broaden the current research and pave a new way to\nmanipulate heat for novel device applications.",
        "positive": "Density functional theory method for twisted geometries with application\n  to torsional deformations in group-IV nanotubes: We present a real-space formulation and implementation of Kohn-Sham Density\nFunctional Theory suited to twisted geometries, and apply it to the study of\ntorsional deformations of X (X = C, Si, Ge, Sn) nanotubes. Our formulation is\nbased on higher order finite difference discretization in helical coordinates,\nuses ab intio pseudopotentials, and naturally incorporates rotational (cyclic)\nand screw operation (i.e., helical) symmetries. We discuss several aspects of\nthe computational method, including the form of the governing equations,\ndetails of the numerical implementation, as well as its convergence, accuracy\nand efficiency properties.\n  The technique presented here is particularly well suited to the first\nprinciples simulation of quasi-one-dimensional structures and their\ndeformations, and many systems of interest can be investigated using small\nsimulation cells containing just a few atoms. We apply the method to\nsystematically study the properties of single-wall zigzag and armchair group-IV\nnanotubes, as they undergo twisting. For the range of deformations considered,\nthe mechanical behavior of the tubes is found to be largely consistent with\nisotropic linear elasticity, with the torsional stiffness varying as the cube\nof the nanotube radius. Furthermore, for a given tube radius, this quantity is\nseen to be highest for carbon nanotubes and the lowest for those of tin, while\nnanotubes of silicon and germanium have intermediate values close to each\nother. We also describe different aspects of the variation in electronic\nproperties of the nanotubes as they are twisted. In particular, we find that\nakin to the well known behavior of armchair carbon nanotubes, armchair\nnanotubes of silicon, germanium and tin also exhibit bandgaps that vary\nperiodically with imposed rate of twist, and that the periodicity of the\nvariation scales in an inverse quadratic manner with the tube radius."
    },
    {
        "anchor": "Self-consistent assessments for the effective properties of two-phase\n  composites within strain gradient elasticity: Analytical method for the second-order homogenization of two-phase composites\nwithin Mindlin-Toupin strain gradient elasticity theory is proposed. Direct\napproach and self-consistent approximation are used to reduce the\nhomogenization problem to the problem of determination of averaged Cauchy\nstresses, double stresses and static moments of Cauchy stresses inside the\ninclusions under prescribed quadratic boundary conditions. The ellipsoidal\nshape of inclusions and orthotropic properties of phases are assumed. Extended\nequivalent inclusion method with linear eigenstrain is proposed to derive the\nexplicit relations between the Eshelby-like tensors and corresponding\nconcentration tensors that are used to define the averaged field variables\ninside the inclusions. Obtained analytical solutions allow to evaluate the\neffective classical and gradient elastic moduli of composite materials\naccounting for the phases properties, volume fraction, shape and size of\ninclusions. Presented solution for the effective gradient moduli covers the\nfull range of volume fraction and correctly predicts the absence of gradient\neffects for the homogeneous classical Cauchy medium. Examples of calculations\nfor the composites with spherical inclusions are given. Micro-scale definition\nof the well-known simplified strain gradient elasticity theory is provided.\nNamely, it is shown that this theory is the phenomenological continuum model\nfor the composites with isotropic matrix and with the small volume fraction of\nstiff isotropic spherical inclusions, which have the same Poisson's ratio to\nthose one of matrix phase.",
        "positive": "First-principles prediction of coexistence of magnetism and\n  ferroelectricity in rhombohedral Bi2FeTiO6: First principles calculations based on the density functional theory within\nthe local spin density approximation plus U(LSDA+U)scheme, show rhombohedral\nBi$_2$FeTiO$_6$ is a potential multiferroic in which the magnetism and\nferroelectricity coexist . A ferromagnetic configuration with magnetic moment\nof 4 $\\mu_B$ per formula unit have been reported with respect to the minimum\ntotal energy. Spontaneous polarization of 27.3 $\\mu$ C/cm$^2$, caused mainly by\nthe ferroelectric distortions of Ti, was evaluated using the berry phase\napproach in the modern theory of polarization. The Bi-6s stereochemical\nactivity of long-pair and the `d$^0$-ness' criterion in off-centring of Ti were\ncoexisting in the predicted new system. In view of the oxidation state of\nBi$^{3+}$,Fe$^{2+}$,Ti$^{4+}$, and O$^{2-}$ from the orbital-resolved density\nof states of the Bi-6p, Fe-3d,Ti-3d, and O-2p states,the valence state of\nBi$_2$FeTiO$_6$ in the rhombohedral phase was found to be\nBi$_2$$^{3+}$Fe$^{2+}$Ti$^{4+}$O$_6$."
    },
    {
        "anchor": "Modulating Electronic Structure of Monolayer Transition Metal\n  Dichalcogenides by Substitutional Nb-Doping: Modulating electronic structure of monolayer transition metal dichalcogenides\n(TMDCs) is important for many applications and doping is an effective way\ntowards this goal, yet is challenging to control. Here we report the in-situ\nsubstitutional doping of niobium (Nb) into TMDCs with tunable concentrations\nduring chemical vapour deposition. Taking monolayer WS2 as an example, doping\nNb into its lattice leads to bandgap changes in the range 1.98 eV to 1.65 eV.\nNoteworthy, electrical transport measurements and density functional theory\ncalculations show that the 4d electron orbitals of the Nb dopants contribute to\nthe density of states of Nb-doped WS2 around the Fermi level, resulting in an n\nto p-type conversion. Nb-doping also reduces the energy barrier of hydrogen\nabsorption in WS2, leading to an improved electrocatalytic hydrogen evolution\nperformance. These results highlight the effectiveness of controlled doping in\nmodulating the electronic structure of TMDCs and their use in electronic\nrelated applications.",
        "positive": "Coarse-graining in micromagnetic simulations of dynamic hysteresis loops: Micromagnetic simulations based on the stochastic Landau-Lifshitz-Gilbert\nequation are used to calculate dynamic magnetic hysteresis loops relevant to\nmagnetic hyperthermia. With the goal to effectively simulate room-temperature\nloops for large iron-oxide-based systems at relatively slow sweep rates on the\norder of 1 Oe/ns or less, a previously derived renormalization group approach\nfor coarse-graining (Grinstein and Koch, Phys. Rev. Lett. 20, 207201, 2003) is\nmodified and applied to calculating loops for a magnetite nanorod. The nanorod\nmodelled is the building block for larger nanoparticles that were employed in\npreclinical studies (Dennis et al., Nanotechnology 20, 395103, 2009). The\nscaling algorithm is shown to produce nearly identical loops over several\ndecades in the model grain size. Sweep-rate scaling involving the Gilbert\ndamping parameter is also demonstrated to allow orders of magnitude speed-up of\nthe loop calculations."
    },
    {
        "anchor": "Amplitude expansion of the phase-field crystal model for complex crystal\n  structures: The phase-field crystal (PFC) model describes crystal lattices at diffusive\ntimescales. Its amplitude expansion (APFC) can be applied to the investigation\nof relatively large systems under some approximations. However, crystal\nsymmetries accessible within the APFC model are limited to basic ones, namely\ntriangular and square in two dimensions, and body-centered cubic and\nface-centered cubic in three dimensions. In this work, we propose a general,\namplitudes-based description of virtually any lattice symmetry. To fully\nexploit the advantages of this model, featuring slowly varying quantities in\nbulk and localized significant variations at dislocations and interfaces, we\nconsider formulations suitable for real-space numerical methods supporting\nadaptive spatial discretization. We explore approaches originally proposed for\nthe PFC model which allow for symmetries beyond basic ones through extended\nparametrizations. Moreover, we tackle the modeling of non-Bravais lattices by\nintroducing an amplitude expansion for lattices with a basis and further\ngeneralizations. We study and discuss the stability of selected, prototypical\nlattice symmetries. As pivotal examples, we show that the proposed approach\nallows for a coarse-grained description of the kagome lattice, exotic square\narrangements, and the diamond lattice, as bulk crystals and, importantly,\nhosting dislocations.",
        "positive": "Importance of interactions for the band structure of the topological\n  Dirac semimetal Na3Bi: We experimentally measure the band dispersions of topological Dirac semimetal\nNa3Bi using Fourier-transform scanning tunneling spectroscopy to image\nquasiparticle interference on the (001) surface of molecular-beam epitaxy-grown\nNa3Bi thin films. We find that the velocities for the lowest-lying conduction\nand valencebands are 1.6x10^6 m/s and 4.2x10^5 m/s respectively, significantly\nhigher than previous theoreticalpredictions. We compare the experimental band\ndispersions to the theoretical band structures calculated usingan increasing\nhierarchy of approximations of self-energy corrections due to interactions:\ngeneralized gradientapproximation (GGA), meta-GGA, Heyd-Scuseria-Ernzerhof\nexchange-correlation functional (HSE06), and GW methods. We find that density\nfunctional theory methods generally underestimate the electron velocities.\nHowever, we find significantly improved agreement with an increasingly\nsophisticated description of the exchange and interaction potential,\nculminating in reasonable agreement with experiments obtained by the GW method.\nThe results indicate that exchange-correlation effects are important in\ndetermining the electronicstructure of this Na3Bi, and are likely the origin of\nthe high velocity. The electron velocity is consistent withrecent experiments\non ultrathin Na3Bi and also may explain the ultrahigh carrier mobility observed\nin heavilyelectron-doped Na3Bi."
    },
    {
        "anchor": "Acoustic collective excitations and static dielectric response in\n  incommensurate crystals with real order parameter: Starting from the basic Landau model for the incommensurate-commensurate\nmaterials of the class II, we derive the spectrum of collective modes for all\n(meta)stable states from the corresponding phase diagram. It is shown that all\nincommensurate states posses Goldstone modes with acoustic dispersions. The\nrepresentation in terms of collective modes is also used in the calculation and\ndiscussion of static dielectric response for systems with the commensurate wave\nnumber in the center of the Brillouin zone.",
        "positive": "On the influence of annealing on the compositional and crystallographic\n  properties of sputtered Li-Al-O thin films: A Li-Al-O thin film materials library, deposited by inert magnetron\nsputtering and post-deposition annealing in O2 atmosphere, was used to study\nthe effects of different annealing temperatures (300 to 850{\\deg}C) and\ndurations (1 min to 7 h) on crystallinity and composition of the films. XPS\ndepth profiling revealed inhomogeneous compositional depth profiles with Li\ncontents increased toward the film surface and Al contents toward the\nfilm-substrate interface. These depth profiles were confirmed by a combination\nof RBS and D-NRA. At annealing temperatures of 550{\\deg}C and higher, Li\nreacted with the Si substrate. At the same time, temperatures of 550{\\deg}C and\nhigher enabled the formation of crystalline LiAlO2, whereas at lower\ntemperatures, no crystalline Li-Al-O phases were detected with XRD. In contrast\nto conventional annealing in a tube furnace (3 to 7 h durations), rapid thermal\nannealing with fast heating/cooling rates of 10{\\deg}C/min and durations of 1\nto 10 min resulted in homogeneous depth profiles, while also leading to\ncrystalline LiAlO2."
    },
    {
        "anchor": "Structural Semiconductor-to-Semimetal Phase Transition in\n  Two-Dimensional Materials Induced by Electrostatic Gating: Dynamic control of conductivity and optical properties via atomic structure\nchanges is of tremendous technological importance in information storage.\nEnergy consumption considerations provide a driving force toward employing thin\nmaterials in devices. Monolayer transition metal dichalcogenides are nearly\natomically-thin materials that can exist in multiple crystal structures, each\nwith distinct electrical properties. Using density functional approaches, we\ndiscover that electrostatic gating device configurations have the potential to\ndrive structural semiconductor-to-semimetal phase transitions in some monolayer\ntransition metal dichalcogenides. For the first time, we show that the\ndynamical control of this phase transition can be achieved in carefully\ndesigned electronic devices. We discover that the semiconductor-to-semimetal\nphase transition in monolayer MoTe2 can be driven by a gate voltage of several\nVolts with appropriate choice of dielectric. Structural transitions in\nmonolayer TaSe2 are predicted to occur under similar conditions. While the\nrequired field magnitudes are large for these two materials, we find that the\ngate voltage for the transition can be reduced arbitrarily by alloying, e.g.\nfor MoxW1-xTe2 monolayers. We have developed a method for computing phase\ndiagrams of monolayer materials with respect to charge and voltage, validated\nby comparing to direct calculations and experimental measurements. Our findings\nidentify a new physical mechanism, not existing in bulk materials, to\ndynamically control structural phase transitions in two-dimensional materials,\nenabling potential applications in phase-change electronic devices.",
        "positive": "Rashba spin splitting of L-gap surface states on Ag(111) and Cu(111): Spin-resolved band structures of L-gap surface states on Ag(111) and Cu(111)\nare investigated by spin- and angle-resolved photoelectron spectroscopy\n(SARPES) with a vacuum-ultra-violet laser. The observed spin textures of the\nAg(111) and Cu(111) surface states agree with that expected by the conventional\nRashba effect. The Rashba parameter of the Ag(111) surface state is estimated\nquantitatively and is 80% of that of Cu(111). The surface-state wave function\nis found to be predominantly of even mirror-symmetry with negligible odd\ncontribution by SARPES using a linearly polarized light. The results are\nconsistent with our theoretical calculations for the orbital-resolved surface\nstate."
    },
    {
        "anchor": "First Principles Calculation of Elastic Moduli of Early-Late Transition\n  Metal Alloys: Motivated by interest in the elastic properties of high strength amorphous\nmetals, we examine the elastic properties of select crystalline phases. Using\nfirst principles methods, we calculate elastic moduli in various chemical\nsystems containing transition metals, specifically early (Ta,W) and late\n(Co,Ni). Theoretically predicted alloy elastic properties are verified for\nNi-Ta by comparison with experimental measurements using resonant ultrasound\nspectroscopy. Comparison of our computed elastic moduli with effective medium\ntheories shows that alloying leads to enhancement of bulk moduli relative to\naverages of the pure elements, and considerable deviation of predicted and\ncomputed shear moduli. Specifically, we find an enhancement of bulk modulus\nrelative to effective medium theory and propose a candidate system for high\nstrength, ductile amorphous alloys. Trends in the elastic properties of\nchemical systems are analyzed using force constants, electronic densities of\nstate and Crystal Overlap Hamilton Populations. We interpret our findings in\nterms of the electronic structure of the alloys.",
        "positive": "A new structure of two-dimensional allotropes of group V elements: The elemental two-dimensional (2D) materials such as graphene, silicene,\ngermanene, and black phosphorus have attracted considerable attention due to\ntheir fascinating physical properties. Structurally they possess the honeycomb\nor distorted honeycomb lattices, which are composed of six-atom rings. Here we\nfind a new structure of 2D allotropes of group V elements composed of\neight-atom rings, which we name as the octagonal tiling (OT) structure.\nFirst-principles calculations indicate that these allotropes are dynamically\nstable and are also thermally stable at temperatures up to 600 K. These\nallotropes are semiconductors with band gaps ranging from 0.3 to 2.0 eV, thus\nthey are potentially useful in near- and mid-infrared optoelectronic devices.\nOT-Bi is also a 2D topological insulator (TI) with a band gap of 0.33 eV, which\nis the largest among the reported elemental 2D TIs, and this gap can be\nincreased further by applying compressive strains."
    },
    {
        "anchor": "Resolving buried interfaces with Low Energy Ion Scattering: We investigate the use of Low Energy Ion Scattering (LEIS) to characterize\nburied interfaces of ultra-thin films. LEIS spectra contain depth-resolved\ninformation in the so-called sub-surface signal. However, the exact correlation\nbetween the sub-surface signal and the depth composition is still unknown. For\nthis reason, LEIS spectra so far only provided qualitative information about\nburied interfaces. In this study, we investigate nm-thin films of Si-on-W and\nSi-on-Mo, where we compare simulated data to LEIS spectra. We present a method\nto extract depth-sensitive compositional changes -- resolving buried interfaces\n-- from LEIS spectra for the first few nanometers of a thin film sample. In the\ncase of Si-on-Mo, the simulation of the LEIS sub-surface signal allows\nobtaining a quantitative measurement of the interface profile that matches the\nvalue determined using the LEIS layer growth profile method with an accuracy of\n0.1 nm. These results pave the way to further extend the use of LEIS for the\ncharacterization of features buried inside the first few nanometers of a\nsample.",
        "positive": "Emergence of Flat-Band Magnetism and Half-Metallicity in Twisted Bilayer\n  Graphene: Evidence of flat-band magnetism and half-metallicity in compressed twisted\nbilayer graphene is provided with first-principles calculations. We show that\ndynamic band-structure engineering in twisted bilayer graphene is possible by\ncontrolling the chemical composition with extrinsic doping, the interlayer\ncoupling strength with pressure, and the magnetic ordering with external\nelectric field. By varying the rotational order and reducing the interlayer\nseparation an unbalanced distribution of charge density resulting in the\nspontaneous apparition of localized magnetic moments without disrupting the\nstructural integrity of the bilayer. Weak exchange correlation between magnetic\nmoments is estimated in large unit cells. External electric field switches the\nlocal magnetic ordering from ferromagnetic to anti-ferromagnetic.\nSubstitutional doping shifts the chemical potential of one spin distribution\nand leads to half-metallicity. Flakes of compressed twisted bilayer graphene\nexhibit spontaneous magnetization, demonstrating that correlation between\nmagnetic moments is not a necessary condition for their formation."
    },
    {
        "anchor": "Chiral phonons in a square lattice: Chiral phonons were initially proposed and further verified experimentally in\ntwo-dimensional (2D) hexagonal crystal lattices. Many intriguing features\nbrought about by chiral phonons are attributed to the pseudo-angular momenta\nwhich are associated with the threefold rotational symmetry of hexagonal\nlattices. Here, we go beyond the hexagonal crystals and investigate the chiral\nphonons in systems with fourfold rotational symmetry. We clarify the symmetry\nrequirements for the emergence of chiral phonons in both 2D square lattices and\n3D tetragonal lattices. For 2D, the realization of $C_4$ chiral phonons\nrequires the breaking of time-reversal symmetry; while for 3D, they can exist\non the $C_4$-invariant path in a chiral tetragonal lattice. These phonons have\nthe advantage that they can be more readily coupled with optical transitions,\nwhich facilitates their experimental detection. We demonstrate our idea via\nmodel analysis and first-principles calculations of concrete materials,\nincluding the MnAs monolayer and the $\\alpha$-cristobalite. Our work reveals\nchiral phonons beyond the hexagonal lattices and paves the way for further\nexploration of chiral phonon physics in square/tetragonal materials and\nmetamaterials.",
        "positive": "Surface Effects On Wetting and Layering Transitions: Wetting phenomena plays an interesting role in the technological development\nof materials. Recently, much attention has been directed to the study of\nmagnetic solid films. To understand, theoretically, the effect of surface on\nwetting and layering transitions in these systems, we will give in this chapter\na presentation of several relevant recent theoretical works realized on wetting\nand layering transitions in which we explain how the nature of surface can\naffect the behavior of wetting and layering transitions. Using different spin\nsystems models and different numerical and approximate methods such as mean\nfield and effective field theories, real space renormalization group technique,\ntransfer matrix method and Monte-Carlo simulations, it is found that the\nwetting and layering transitions depend on the nature of the surface magnetic\nfield, the surface coupling strength, the surface crystal field, the geometry\nof surface, the in-homogeneity of substrate and the quantum fluctuations at the\nsurface&#65533;"
    },
    {
        "anchor": "Evolution from sinusoidal to collinear A-type antiferromagnetic\n  spin-ordered magnetic phase transition in Tb0.6Pr0.4MnO3: The present study reports on the structural and magnetic phase transitions in\nPr-doped polycrystalline Tb0.6Pr0.4MnO3, using high-resolution neutron powder\ndiffraction (NPD) collected at SINQ spallation source (PSI), to emphasize the\nsuppression of the sinusoidal magnetic structure of pure TbMnO3 and the\nevolution to a collinear A-type antiferromagnetic ordering. The phase purity,\nJahn-Teller distortion, and one-electron bandwidth for eg orbital of Mn3+\ncation have been calculated for polycrystalline Tb0.6Pr0.4MnO3, in comparison\nto the parent materials TbMnO3 and PrMnO3, through the Rietveld refinement\nstudy from X-ray diffraction data at room temperature. The\ntemperature-dependent zero field-cooled and field-cooled dc magnetization study\nat low temperature down to 5 K reveals a variation in the magnetic phase\ntransition due to the effect of Pr3+ substitution at the Tb3+ site, which gives\nthe signature of the antiferromagnetic nature of the sample, with a weak\nferromagnetic component at low temperature induced by an external magnetic\nfield. The field-dependent magnetization study at low temperatures gives the\nweak coercivity having the order of 2 kOe, which is expected due to canted-spin\narrangement or ferromagnetic nature of Terbium ordering. The NPD data for\nTb0.6Pr0.4MnO3 confirms that the nuclear structure of the synthesized sample\nmaintains its orthorhombic symmetry down to 1.5 K. Also, the magnetic\nstructures have been solved at 50 K, 25 K, and 1.5 K through the NPD study,\nwhich shows A-type antiferromagnetic spin arrangement.",
        "positive": "Large-amplitude chirped coherent phonons in tellurium mediated by\n  ultrafast photoexcited carrier diffusion: We report femtosecond time-resolved reflectivity measurements of coherent\nphonons in tellurium performed over a wide range of temperatures (3K to 296K)\nand pump laser intensities. A totally symmetric A$_{1}$ coherent phonon at 3.6\nTHz responsible for the oscillations in the reflectivity data is observed to be\nstrongly positively chirped (i.e, phonon time period decreases at longer\npump-probe delay times) with increasing photoexcited carrier density, more so\nat lower temperatures. We show for the first time that the temperature\ndependence of the coherent phonon frequency is anomalous (i.e, increasing with\nincreasing temperature) at high photoexcited carrier density due to\nelectron-phonon interaction. At the highest photoexcited carrier density of\n$\\sim$ 1.4 $\\times$ 10$^{21}$cm$^{-3}$ and the sample temperature of 3K, the\nlattice displacement of the coherent phonon mode is estimated to be as high as\n$\\sim$ 0.24 \\AA. Numerical simulations based on coupled effects of optical\nabsorption and carrier diffusion reveal that the diffusion of carriers\ndominates the non-oscillatory electronic part of the time-resolved\nreflectivity. Finally, using the pump-probe experiments at low carrier density\nof 6 $\\times$ 10$^{18}$ cm$^{-3}$, we separate the phonon anharmonicity to\nobtain the electron-phonon coupling contribution to the phonon frequency and\nlinewidth."
    },
    {
        "anchor": "Projector augmented-wave and all-electron calculations across the\n  periodic table: a comparison of structural and energetic properties: We construct a reference database of materials properties calculated using\ndensity-functional theory in the local or generalized-gradient approximation,\nand an all-electron or a projector augmented-wave (PAW) formulation, for\nverification and validation of first-principles simulations. All-electron\ncalculations use the full-potential linearised augmented-plane wave method, as\nimplemented in the \\texttt{Elk} open-source code, while PAW calculations use\nthe datasets developed by some of us in the open-source \\texttt{PSlibrary}\nrepository and the \\texttt{Quantum ESPRESSO} distribution. We first calculate\nlattice parameters, bulk moduli, and energy differences for alkaline metals,\nalkaline earths, and $3d$ and $4d$ transition metals in three ideal, reference\nphases (simple cubic, fcc, and bcc), representing a standardized crystalline\nmonoatomic solid-state test. Then, as suggested by K. Lejaeghere {\\it et al.},\n[Critical Reviews in Solid State and Material Sciences 39, p 1 (2014)], we\ncompare the equations of state for all elements, except lanthanides and\nactinides, in their experimental phase (or occasionally a simpler, closely\nrelated one). PAW and all-electron energy differences and structural parameters\nagree in most cases within a few meV/atom and a fraction of a percent,\nrespectively. This level of agreement, comparable with the previous study,\nincludes also other PAW and all-electron data from the electronic-structure\ncodes \\texttt{VASP} and \\texttt{WIEN2K}, and underscores the overall\nreliability of current, state-of-the-art electronic-structure calculations. At\nthe same time, discrepancies that arise even within the same formulation for\nsimple, fundamental structural properties point to the urgent need of\nestablishing standards for verification and validation, reference data sets,\nand careful refinements of the computational approaches used.",
        "positive": "New Quantum Spin Hall Insulator in Two-dimensional MoS$_2$ with\n  Periodically Distributed Pores: MoS$_2$, one of transition metal dichalcogenides (TMDs), has caused a lot of\nattentions for its excellent semiconductor characteristics and potential\napplications. Here, based on the density functional theory methods, we predict\na novel 2D quantum spin hall (QSH) insulator in the porous allotrope of\nmonolayer MoS$_2$ (g-MoS$_2$), consisting of MoS$_2$ square and hexagon. The\ng-MoS$_2$ has a nontrivial gap as large as 109 meV, comparable with previous\nreported 1T'-MoS$_2$ (80 meV), so-MoS$_2$ (25 meV). We demonstrate that the\norigin of 2D QSH effect in g-MoS$_2$ originates from the pure d-d band\ninteraction, different from conventional band inversion between s$-$p, p$-$p or\nd$-$p orbitals. Such new polymorph greatly enriches the TMDs family and its\nstabilities are confirmed by phonon spectrum analysis. In particular, porous\nstructure also endows it potential application in efficient gas separation and\nenergy storage."
    },
    {
        "anchor": "Spin-wave stiffness and micromagnetic exchange interactions expressed by\n  means of the KKR Green function approach: We represent an approach to calculate micromagnetic model parameters such as\nthe tensor of exchange stiffness, Dzyaloshinskii-Moriya interaction (DMI) as\nwell as spin-wave stiffness. The scheme is based on the fully relativistic\nKorringa-Kohn-Rostoker Green function (KKR-GF) technique and can be seen as a\nrelativistic extension of the work of Lichtenstein {\\em et al.} The expression\nfor $D^{z\\alpha}$ elements of DMI differ from the expressions for $D^{x\\alpha}$\nand $D^{y\\alpha}$ elements as the former are derived via second-order\nperturbation term of the energy caused by spin-spiral while the latter are\nassociated with the first-order term. Corresponding numerical results are\ncompared with those obtained using other schemes reported in the literature.",
        "positive": "From pseudomorphic to orthomorphic growth of Fe films on Cu3Au(001): A few theoretical models predict Fe to display both ferromagnetic and\nantiferromagnetic phases, depending on the volume of the unit cell. A proper\nchoice of the substrate allows the growth of thin Fe overlayers with structures\ndifferent from the bcc bulk one. The Cu3Au(001) substrate is a suitable\ncandidate for testing these magnetic properties since it has a lattice\nparameter (3.75 Angstroms) which lies closer to the ferromagnetic fcc Fe phase\n(3.66 Angstroms) than to the ferromagnetic bcc phase (4.07 Angstroms). We have\ninvestigated Fe films up to 40 Angstroms thickness by means of Grazing\nIncidence X-Ray Diffraction (GIXRD) and Photo/Auger--Electron Diffraction (ED).\nThe combination of GIXRD and ED allows one to obtain quantitative information\non the in--plane spacing \"a\" from the former technique, and the ratio between\nthe vertical spacing \"c\" and \"a\", from the latter one. At low coverage the film\ngrows pseudomorphic to the fcc substrate up to a limit thickness of 8\nAngstroms. Above this limit the film is characterized by the coexistence of the\npseudomorphic phase with another tetragonally strained phase. The latter phase\nis shown to fall on the epitaxial curve of tetragonally distorted fcc Fe phase.\nFinally, above 17 Angstroms the development of a body centered phase \"alpha\",\nwhose unit cell is rotated of 45 deg. with respect to the substrate one, has\nbeen clearly observed. \"alpha\" is the dominating phase for film thickness\nhigher than 25 Angstroms and its lattice constant evolves towards the\northomorphic phase in strict quantitative agreement with epitaxial curves\ncalculated for the tetragonally distorted bcc iron phase."
    },
    {
        "anchor": "Thermally Driven Long Range Magnon Spin Currents in Yttrium Iron Garnet\n  due to Intrinsic Spin Seebeck Effect: The longitudinal spin Seebeck effect refers to the generation of a spin\ncurrent when heat flows across a normal metal/magnetic insulator interface.\nUntil recently, most explanations of the spin Seebeck effect use the\ninterfacial temperature difference as the conversion mechanism between heat and\nspin fluxes. However, recent theoretical and experimental works claim that a\nmagnon spin current is generated in the bulk of a magnetic insulator even in\nthe absence of an interface. This is the so-called intrinsic spin Seebeck\neffect. Here, by utilizing a non-local spin Seebeck geometry, we provide\nadditional evidence that the total magnon spin current in the ferrimagnetic\ninsulator yttrium iron garnet (YIG) actually contains two distinct terms: one\nproportional to the gradient in the magnon chemical potential (pure magnon spin\ndiffusion), and a second proportional to the gradient in magnon temperature\n($\\nabla T_m$). We observe two characteristic decay lengths for magnon spin\ncurrents in YIG with distinct temperature dependences: a temperature\nindependent decay length of ~ 10 ${\\mu}$m consistent with earlier measurements\nof pure ($\\nabla T_m = 0$) magnon spin diffusion, and a longer decay length\nranging from about 20 ${\\mu}$m around 250 K and exceeding 80 ${\\mu}$m at 10 K.\nThe coupled spin-heat transport processes are modeled using a finite element\nmethod revealing that the longer range magnon spin current is attributable to\nthe intrinsic spin Seebeck effect ($\\nabla T_m \\neq 0$), whose length scale\nincreases at lower temperatures in agreement with our experimental data.",
        "positive": "Self-consistent calculation of spin transport and magnetization dynamics: A spin-polarized current transfers its spin-angular momentum to a local\nmagnetization, exciting current-induced magnetization dynamics. So far, most\nstudies in this field have focused on the direct effect of spin transport on\nmagnetization dynamics, but ignored the feedback from the magnetization\ndynamics to the spin transport and back to the magnetization dynamics. Although\nthe feedback is usually weak, there are situations when it can play an\nimportant role in the dynamics. In such situations, self-consistent\ncalculations of the magnetization dynamics and the spin transport can\naccurately describe the feedback. This review describes in detail the feedback\nmechanisms, and presents recent progress in self-consistent calculations of the\ncoupled dynamics. We pay special attention to three representative examples,\nwhere the feedback generates non-local effective interactions for the\nmagnetization. Possibly the most dramatic feedback example is the dynamic\ninstability in magnetic nanopillars with a single magnetic layer. This\ninstability does not occur without non-local feedback. We demonstrate that full\nself-consistent calculations generate simulation results in much better\nagreement with experiments than previous calculations that addressed the\nfeedback effect approximately. The next example is for more typical spin valve\nnanopillars. Although the effect of feedback is less dramatic because even\nwithout feedback the current can induce magnetization oscillation, the feedback\ncan still have important consequences. For instance, we show that the feedback\ncan reduce the linewidth of oscillations, in agreement with experimental\nobservations. Finally, we consider nonadiabatic electron transport in narrow\ndomain walls. The non-local feedback in these systems leads to a significant\nrenormalization of the effective nonadiabatic spin transfer torque."
    },
    {
        "anchor": "Two- and Three-Particle Complexes with Logarithmic Interaction: Compact\n  Wave Functions for Two-Dimensional Excitons and Trions: Assuming a logarithmic interaction between constituent particles, compact and\nlocally accurate wave functions that describe bound states of the two-particle\nneutral and three-particle charged complexes in two dimensions are designed.\nPrime examples of these complexes are excitons and trions that appear in\nmonolayers of Transition-Metal DichalCogenides (TMDCs). In the case of\nexcitons, these wave functions led to 5-6 correct decimal digits in the energy\nand the diamagnetic shifts. In addition, it is demonstrated that they can be\nused as zero-order approximations to study magnetoexcitons via perturbation\ntheory in powers of the magnetic field strength. For the trion, making a\ncomparison with experimental data for concrete TMDCs, we established that the\nlogarithmic potential leads to binding energies $\\lesssim 25\\%$ greater than\nexperimental ones. Finally, the structure of the wave function at small\ndistances is established for excitons whose carriers interact via the\nRytova-Keldysh potential.",
        "positive": "New Insights into the Compressibility and High-Pressure Stability of\n  Ni(CN)2 from Neutron Diffraction, Raman Spectroscopy and Inelastic Neutron\n  Scattering: The layered structure of tetragonal Ni(CN)2, consisting of square-planar\nNi(CN)4 units linked in the a-b plane, with no true periodicity along the\nc-axis, is expected to show anisotropic compression on the application of\npressure. High-pressure neutron diffraction (elastic) and inelastic neutron\nscattering experiments have been performed on polycrystalline Ni(CN)2 to\ninvestigate its compressibility and stability. The intralayer a lattice\nparameter does not show any appreciable variation with increase of pressure up\nto 2.7 kbar. Above this pressure value, a decrease in a is observed. The c\nlattice parameter decreases slowly up to 1 kbar, then decreases sharply up to\n20 kbar. It does not show any significant variation with further pressure\nincrease up to 50 kbar. The response of the lattice parameters to the applied\npressure is strongly anisotropic as the interlayer spacing (along the c-axis)\nshows a significantly larger contraction than the a-b plane. The experimental\npressure dependence of the volume data is fitted to a bulk modulus, B0, of 1050\n(20) kbar over the pressure range 0-1 kbar, and to 154 (2) kbar in the range\n1-50 kbar. The change in the slope of the lattice parameters at 1 kbar is also\nsupported by high-pressure Raman measurements, which indicate a phase\ntransition at 1 kbar. Probably arising from a change in the CN ordering within\nthe Ni(CN)2 layers. Raman measurements, performed up to 200 kbar, highlight the\npossible existence of a second phase transition taking place at about 70 kbar.\nOur neutron inelastic scattering measurements of the pressure dependence of the\nphonon spectra performed up to 2.7 kbar, also support the occurrence of a phase\ntransition at low pressure."
    },
    {
        "anchor": "Charge density wave and superconductivity in the kagome metal\n  CsV$_3$Sb$_5$ around a pressure-induced quantum critical point: Using first-principles density functional theory calculations, we investigate\nthe pressure-induced quantum phase transition (QPT) from the charge density\nwave (CDW) to the pristine phase in the layered kagome metal CsV$_3$Sb$_5$\nconsisting of three-atom-thick Sb$-$V$_3$Sb$-$Sb and one-atom-thick Cs layers.\nThe CDW structure having the formation of trimeric and hexameric V atoms with\nbuckled Sb honeycomb layers features an increase in the lattice parameter along\nthe $c$ axis, compared to its counterpart pristine structure having the ideal\nV$_3$Sb kagome and planar Sb honeycomb layers. Consequently, as pressure\nincreases, the relatively smaller volume of the pristine phase contributes to\nreducing the enthalpy difference between the CDW and pristine phases, yielding\na pressure-induced QPT at a critical pressure $P_c$ of ${\\sim}$2 GPa.\nFurthermore, we find that (i) the superconducting transition temperature $T_c$\nincreases around $P_c$ due to a phonon softening associated with the periodic\nlattice distortion of V trimers and hexamers and that (ii) above $P_c$, optical\nphonon modes are hardened with increasing pressure, leading to monotonous\ndecreases in the electron-phonon coupling constant and $T_c$. Our findings not\nonly demonstrate that the uniaxial strain along the $c$ axis plays an important\nrole in the QPT observed in CsV$_3$Sb$_5$, but also provide an explanation for\nthe observed superconductivity around $P_c$ in terms of a phonon-mediated\nsuperconducting mechanism.",
        "positive": "Driving Forces and Boundary Conditions in Continuum Dislocation\n  Mechanics: As a guide to constitutive specification, driving forces for dislocation\nvelocity and nucleation rates are derived for a field theory of dislocation\nmechanics. A condition of closure for the theory in the form of a boundary\ncondition for dislocation density is also derived. Kinematical features of\ndislocation evolution like initiation of bowing of a pinned screw segment, and\ninitiation of cross-slip of a screw segment are discussed. An exact solution\nfor the expansion of a polygonal loop as well as representation within the\ntheory of dislocation level Schmid and non-Schmid behavior, and unloaded\nstress-free and steady microstructures are also discussed."
    },
    {
        "anchor": "Coherent Helicity-Dependent Spin-Phonon Oscillations in the\n  Ferromagnetic van der Waals Crystal CrI3: The discovery of two-dimensional (2D) systems hosting intrinsic long-range\nmagnetic order represents a seminal addition to the rich physical landscape of\nvan der Waals (vdW) materials. CrI3 has emerged as perhaps the most salient\nexample, as the interdependence of crystalline structure and magnetic order,\nalong with strong light-matter interactions provides a promising platform to\nexplore the optical control of magnetic, vibrational, and charge degrees of\nfreedom at the 2D limit. However, the fundamental question of how this\nrelationship between structure and magnetism manifests on their intrinsic\ntimescales has rarely been explored. Here, we use ultrafast optical\nspectroscopy to probe magnetic and vibrational dynamics in CrI3, revealing\ndemagnetization dynamics governed by spin-flip scattering and remarkably, a\nstrong transient exchange-mediated interaction between lattice vibrations and\nspin oscillations. The latter yields a coherent spin-coupled phonon mode that\nis highly sensitive to the helicity of the driving pulse in the magnetically\nordered phase. Our results shed light on the nature of spin-lattice coupling in\nvdW magnets on ultrafast timescales and highlight their potential for\napplications requiring non-thermal, high-speed control of magnetism at the\nnanoscale.",
        "positive": "Escape from the Second Dimension: A Topological Distinction Between Edge\n  and Screw Dislocations: Volterra's definition of dislocations in crystals distinguishes edge and\nscrew defects geometrically, according to whether the Burgers vector is\nperpendicular or parallel to the defect. Here, we demonstrate a distinction\nbetween screw and edge dislocations that enables a unified, purely topological\nmeans of classification. Our construction relies on the construction of real or\nvirtual disclination-line pairs at the core of the dislocation in a smectic and\ncan be generalized to crystals with triply-periodic order. The connection\nbetween topology and geometry is exploited."
    },
    {
        "anchor": "Efficient implementation of the GW approximation within the all-electron\n  FLAPW method: We present an implementation of the GW approximation for the electronic\nself-energy within the full-potential linearized augmented-plane-wave (FLAPW)\nmethod. The algorithm uses an all-electron mixed product basis for the\nrepresentation of response matrices and related quantities. This basis is\nderived from the FLAPW basis and is exact for wave-function products. The\nsingularity of the bare and screened interaction potentials gives rise to a\nnumerically important self-energy contribution, which we treat analytically to\nachieve good convergence with respect to the k-point sampling. As numerical\nrealizations of the GW approximation typically suffer from the high\ncomputational expense required for the evaluation of the nonlocal and\nfrequency-dependent self-energy, we demonstrate how the algorithm can be made\nvery efficient by exploiting spatial and time-reversal symmetry as well as by\napplying an optimization of the mixed product basis that retains only the\nnumerically important contributions of the electron-electron interaction.\nFurthermore, we demonstrate that one can employ an extrapolar approximation for\nhigh-lying states to reduce the number of empty states that must be taken into\naccount explicitly in the construction of the polarization function and the\nself-energy. We show convergence tests, CPU timings, and results for prototype\nsemiconductors and insulators as well as ferromagnetic nickel.",
        "positive": "The Structure of GaSb Digitally Doped with Mn: Cross sectional scanning tunneling microscopy (XSTM) and density functional\ntheory have been used to characterize the structure of GaSb digitally doped\nwith Mn. The Mn dopants are found in both isolated substitutional form as well\nas in large clusters of zinc-blende MnSb commensurate with the surrounding GaSb\nmatrix. Theoretical calculations predict that these two forms of Mn in the\ndigitally doped layers will have a very different appearance in XSTM images.\nSubstitutional Mn enhances the local density of states near the surface, thus\nappearing higher in a filled-state image. In contrast, MnSb clusters induce\nsubstantial structural relaxation at the {110} surface, and therefore appear as\nlocalized depressed regions with negligible perturbation of the surrounding\nGaSb."
    },
    {
        "anchor": "Nature of Radiation-Induced Defects in Quartz: Although quartz ($\\rm \\alpha$-form) is a mineral used in numerous\napplications wherein radiation exposure is an issue, the nature of the\natomistic defects formed during radiation-induced damage have not been fully\nclarified. Especially, the extent of oxygen vacancy formation is still debated,\nwhich is an issue of primary importance as optical techniques based on charged\noxygen vacancies have been utilized to assess the level of radiation damage in\nquartz. In this paper, molecular dynamics (MD) simulations are applied to study\nthe effects of ballistic impacts on the atomic network of quartz. We show that\nthe defects that are formed mainly consist of over-coordinated Si and O, as\nwell as Si--O connectivity defects, e.g., small Si--O rings and edge-sharing Si\ntetrahedra. Oxygen vacancies, on the contrary, are found in relatively low\nabundance, suggesting that characterizations based on $E^{\\prime}$ centers do\nnot adequately capture radiation-induced structural damage in quartz. Finally,\nwe evaluate the dependence on the incident energy, of the amount of each type\nof the point defects formed, and quantify unambiguously the threshold\ndisplacement energies for both O and Si atoms. These results provide a\ncomprehensive basis to assess the nature and extent of radiation damage in\nquartz.",
        "positive": "Martensitic transformation in zirconia. Part II: Martensite growth: Though the martensitic transformation in zirconia has been the object of a\nvery large number of studies for the last decades, qualitative and quantitative\nobservations of the formation and growth of relief induced by low temperature\ntreatments has hardly ever been reported. In the first part of the study, we\nhave demonstrated the excellent agreement between the atomic force microscopy\nquantitative observations and the outputs of the calculations derived from the\nphenomenological theory of martensitic transformation. The intermediate stages\nof transformation were nonetheless not considered. In this second part, the\ngrowth mechanisms of monoclinic phase resulting from the martensitic\ntransformation in ceria-stabilized zirconia (10 mol% CeO2) are investigated.\nSurface transformation is induced by ageing treatments in water vapor at 413 K.\nThe observations are rationalized by the recent analysis proposed for the\ncrystallographic ABC1 correspondence choice, where the ct axis transforms to\nthe cm axis. Three growth modes are observed and interpreted in terms of\ntransformation strains accommodation. Microcracks formation is observed,\nexplaining grain pop-out where the crystallographic disorientation between two\nadjacent grains is the largest. The influence of grain boundary paths on the\nsurface relief features is demonstrated. Overall, our results strongly support\nthe non-existence of a critical grain size for low temperature transformation,\nconfirmed by the classical thermodynamics theory applied to this particular\ncase."
    },
    {
        "anchor": "Evaluation of Half-metallic Antiferromagnetism in ${\\cal A}_2$CrFeO$_6$\n  ({$\\cal A$}=La, Sr: The nearly well-ordered double perovskite La$_2$CrFeO$_6$ has been\nsynthesized recently. Contrary to previous theoretical predictions, but in\nagreement with experimental observations, our first principle calculations\nindicate an insulating ferrimagnet La$_2$CrFeO$_6$ with antialigned S=3/2\nCr$^{3+}$ and S=5/2 Fe$^{3+}$ ions,using the local spin density approximation\n(LSDA), a correlated band theory LDA+U, and a semilocal functional modified\nBecke-Johnson method. Additionally, we investigated the double perovskite\nSr$_2$CrFeO$_6$, which is as yet unsynthesized. In LSDA calculations, this\nsystem shows formally tetravalent Cr and Fe ions both having antialigned $S$=1\nmoments, but is a simple metal. Once applying on-site Coulomb repulsion U on\nboth Cr and Fe ions, this system becomes half-metallic and the moment of Fe is\nsubstantially reduced, resulting in zero net moment. These results are\nconsistent with our fixed spin moment studies. Our results suggest a precisely\ncompensated half-metallic Sr$_2$CrFeO$_6$.",
        "positive": "Influence of plural scattering on the quantitative determination of spin\n  and orbital moments in electron magnetic circular dichroism measurements: Recent quantitative measurements of the orbital to spin magnetic moment ratio\n$m_L/m_S$ in electron magnetic circular dichroism (EMCD) experiments have given\na $m_L/m_S$ ratio that is larger than commonly accepted values. We demonstrate\nhere that plural scattering may noticeably influence the $m_L/m_S$ ratio. An\nequation is derived which describes its influence as a function of the spectral\nintegrals of the plasmon scattering region and zero-loss peak. The influence of\nthe electron-plasmon scattering can be removed when electron energy-loss\nspectra of the ionization edge are deconvoluted by the low-loss signal. For a\nbcc-Fe sample we obtain $m_L/m_S=0.04$ after plasmon removal. We conclude that\nthe plural scattering should be considered when extracting quantitative\ninformation from EMCD measurements."
    },
    {
        "anchor": "One million percent tunnel magnetoresistance in a magnetic van der Waals\n  heterostructure: We report the observation of a very large negative magnetoresistance effect\nin a van der Waals tunnel junction incorporating a thin magnetic semiconductor,\nCrI3, as the active layer. At constant voltage bias, current increases by\nnearly one million percent upon application of a 2 Tesla field. The effect\narises from a change between antiparallel to parallel alignment of spins across\nthe different CrI3 layers. Our results elucidate the nature of the magnetic\nstate in ultrathin CrI3 and present new opportunities for spintronics based on\ntwo-dimensional materials.",
        "positive": "Complex Chiral Modulations in FeGe close to Magnetic Ordering: We report on detailed polarized small-angle neutron scattering on cubic FeGe\nin magnetic fields applied either along (transverse) the scattering vector or\nparallel (longitudinal)to the neutron beam. The ($H,T$) phase diagrams for all\nprincipal axes contain a segmented $A$-phase region just below the onset of\nmagnetic order. Hexagonal Bragg-spot patterns were observed across the entire\n$A$-phase region for the longitudinal geometry. Scattering intensity was\nobserved in parts of the A phase for both scattering configurations. Only in a\ndistinct pocket ($A_1$) vanishing scattering intensity was found in the\ntransverse geometry."
    },
    {
        "anchor": "Emergent Dirac carriers across a pressure-induced Lifshitz transition in\n  black phosphorus: The phase diagrams of correlated systems like cuprates or pnictides\nhigh-temperature superconductors are characterized by a topological change of\nthe Fermi surface under continuous variation of an external parameter, the\nso-called Lifshitz transition. However, the large number of low-temperature\ninstabilities and the interplay of multiple energy scales complicate the study\nof this phenomenon. Here we first identify the optical signatures of a\npressure-induced Lifshitz transition in a clean elemental system, black\nphosphorus. By applying external pressures above 1.5 GPa, we observe a change\nin the pressure dependence of the Drude plasma frequency due to the appearance\nof massless Dirac fermions. At higher pressures, optical signatures of two\nstructural phase transitions are also identified. Our findings suggest that a\nkey fingerprint of the Lifshitz transition in solid state systems, and in\nabsence of structural phase transitions, is a discontinuity of the Drude plasma\nfrequency due to the change of Fermi surface topology.",
        "positive": "Electronic structure of short-period ZnSe/ZnTe superlattices based on\n  DFT calculations: In the present study we discuss the effect of variation in the number of\nmonolayers $n$ on the electronic and optical properties of superlattices (SLs)\n(ZnSe)$_n$/(ZnTe)$_n$. The total energies were calculated by the full-potential\nlinear muffin-tin orbital (FP-LMTO) method, and the exchange-correlation energy\nwas applied in the local density approximation (LDA). First, the calculations\nshow a decrease in the derivative of bulk modulus and electronic bandgap with\nan increase in the number of monolayers $n$. Second, the radiation energies up\nto $15$ eV, the dielectric function $\\varepsilon(\\omega$), the refractive index\n$n(\\omega)$, and the reflectivity $R(\\omega)$ are studied. These calculations\nmay be beneficial to understand the properties of short-period superlattices\n(ZnSe)$_n$/(ZnTe)$_n$."
    },
    {
        "anchor": "Clustering kinetics during natural ageing of Al-Cu based alloys with\n  (Mg, Li) additions: Room temperature solute clustering in aluminium alloys, or natural ageing,\ndespite its industrial relevance, is still subject to debate, mostly due to its\nexperimentally challenging nature. To better understand the complex\nmulti-constituents' interactions at play, we have studied ternary and\nquaternary subsystems based on the Al-Cu alloys, namely Al-Cu-Mg, Al-Cu-Li and\nAl-Cu-Li-Mg. We used a recently introduced correlative technique using\nsmall-angle neutrons and X-ray scattering (SANS and SAXS) to extract the\nchemically resolved kinetics of room temperature clustering in these alloys,\nwhich we completed with differential scanning calorimetry (DSC) and\nmicro-hardness measurements. The comparison of the clustering behaviours of\neach subsystem allowed us to highlight the paramount role of Mg as a trigger\nfor diffusion and clustering. Indeed, while a strong natural ageing was\nobserved in the Al-Cu-Mg alloy, virtually none was shown for Al-Cu-Li. A very\nslight addition of Mg (0.4%) to this system, however, drastically changed the\nsituation to a rapid formation of essentially Cu-rich hardening clusters, Mg\nonly joining them later in the reaction. This diffusion enabling effect of Mg\nis discussed in terms of diffusion mechanism and complex interactions with the\nquenched-in vacancies.",
        "positive": "Turning many-body problems to few-body ones in photoexcited\n  semiconductors using the stochastic variational method in momentum space,\n  SVM-k: We develop an efficient computational technique to calculate composite\nexcitonic states in photoexcited semiconductors through the stochastic\nvariational method (SVM). Many-body interactions between an electron gas and\nthe excitonic state are embodied in the problem through Fermi holes in the\nconduction band, introduced when electrons are pulled out of the Fermi sea to\nbind the photoexcited electron-hole pair. We consider the direct Coulomb\ninteraction between distinguishable particles in the complex, the\nexchange-induced band-gap renormalization effect, and electron-hole exchange\ninteraction between an electron and its conduction-band hole. We provide\nanalytical expressions for potential matrix elements, using a technique that\nallows us to circumvent the difficulty imposed by the occupation of low-energy\nelectron states in the conduction band. We discuss the computational steps one\nshould implement in order to perform the calculation, and how to extract\nkinetic energies of individual particles in the complex, average inter-particle\ndistances, and density distributions."
    },
    {
        "anchor": "Disentangling Scaling Properties in Anisotropic Fracture: Structure functions of rough fracture surfaces in isotropic materials exhibit\ncomplicated scaling properties due to the broken isotropy in the fracture plane\ngenerated by a preferred propagation direction. Decomposing the structure\nfunctions into the even order irreducible representations of the SO(2) symmetry\ngroup (indexed by $m=0,2,4...$) results in a lucid and quickly convergent\ndescription. The scaling exponent of the isotropic sector ($m=0$) dominates at\nsmall length scales. One can reconstruct the anisotropic structure functions\nusing only the isotropic and the first non vanishing anisotropic sector ($m=2$)\n(or at most the next one ($m=4$)). The scaling exponent of the isotropic sector\nshould be observed in a proposed, yet unperformed, experiment.",
        "positive": "Monte Carlo simulations of the kagome lattice with magnetic dipolar\n  interactions: The results of extensive Monte Carlo simulations of classical spins on the\ntwo-dimensional kagome lattice with only dipolar interactions are presented. In\naddition to revealing the six-fold degenerate ground state, the nature of the\nfinite-temperature phase transition to long-range magnetic order is discussed.\nLow temperature states consisting of mixtures of degenerate ground state\nconfigurations separated by domain walls can be explained as a result of\ncompeting exchange-like and shape anisotropy-like terms in the dipolar\ncoupling. Fluctuations between pairs of degenerate spin configurations are\nfound to persist well into the ordered state as the temperature is lowered\nuntil locking in to a low-energy state."
    },
    {
        "anchor": "The electronic structure of the Na$_x$CoO$_2$ surface: The idea that surface effects may play an important role in suppressing\n$e_g'$ Fermi surface pockets on Na$_x$CoO$_2$ $(0.333 \\le x \\le 0.75)$ has been\nfrequently proposed to explain the discrepancy between LDA calculations\n(performed on the bulk compound) which find $e_g$' hole pockets present and\nARPES experiments, which do not observe the hole pockets. Since ARPES is a\nsurface sensitive technique it is important to investigate the effects that\nsurface formation will have on the electronic structure of Na$_{1/3}$CoO$_2$ in\norder to more accurately compare theory and experiment. We have calculated the\nband structure and Fermi surface of cleaved Na$_{1/3}$CoO$_2$ and determined\nthat the surface non-trivially affects the fermiology in comparison to the\nbulk. Additionally, we examine the likelihood of possible hydroxyl cotamination\nand surface termination. Our results show that a combination of surface\nformation and contamination effects could resolve the ongoing controversy\nbetween ARPES experiments and theory.",
        "positive": "Single-shot laser-induced switching of an exchange biased\n  antiferromagnet: Ultrafast manipulation of magnetic order has challenged our understanding the\nfundamental and dynamic properties of magnetic materials. So far single shot\nmagnetic switching has been limited to ferrimagnetic alloys and multilayers. In\nferromagnetic (FM)/antiferromagnetic (AFM) bilayers, exchange bias (He) arises\nfrom the interfacial exchange coupling between the two layers and reflects the\nmicroscopic orientation of the antiferromagnet. Here we demonstrate the\npossibility of single shot switching of the antiferromagnet (change of the sign\nand amplitude of He) with a single femtosecond laser pulse in IrMn/CoGd\nbilayers. We demonstrate the switching for a wide range of fluences for\ndifferent layer thicknesses and compositions. Atomistic simulations predict\nultrafast switching and recovery of the AFM magnetization on a timescale of 2\nps. These results provide the fastest and the most energy-efficient method to\nset the exchange bias and pave the way to potential applications for ultrafast\nspintronic devices."
    },
    {
        "anchor": "The Effect of Structural Phase Changes on Fermi Level Shifts and\n  Optoelectronic Properties of Lead-Free CsSnI3 Perovskites: The work carried out first-principles calculations within the framework of\ndensity functional theory to study the structural stability of the CsSnI3\ncompound and the influence of phase transitions on their electronic and optical\nproperties. Using the GGA and SCAN functionals, the relaxed structures of the\nCsSnI3 phases were obtained and their geometric characteristics were assessed.\nUsing the Phonopy code based on VASP, calculations of phonon and thermodynamic\nproperties were performed, and the temperatures of phase transitions of CsSnI3\nwere determined. Electronic properties and Fermi level shifts as a result of\nphase transformations of CsSnI3 were assessed using the HSE06 functional and\nmachine learning prediction. The values of the complex dielectric constant and\nthe refractive index of all phases of the CsSnI3 were determined.",
        "positive": "Electronic entropy in Green's-function calculations at finite\n  temperatures: We revise critically existing approaches to evaluation of thermodynamic\npotentials within the Green's function calculations at finite electronic\ntemperatures. We focus on the entropy and show that usual technical problems\nrelated to the multivalued nature of the complex logarithm can be overcome.\nThis results in a simple expression for the electronic entropy, which does not\nrequire any contour integration in the complex energy plane. Properties of the\ndeveloped formalism are discussed and its illustrating applications to selected\nmodel systems and to bcc iron with disordered local magnetic moments are\npresented as well."
    },
    {
        "anchor": "Substrate Effect on Optical Properties of Insulator-Metal Transition in\n  VO2 Thin Films: In this paper we used Raman spectroscopy to investigate the optical\nproperties of vanadium dioxide (VO2) thin films during the thermally induced\ninsulating to metallic phase transition. We observed a significant difference\nin transition temperature in similar VO2 films grown on quartz and sapphire\nsubstrates: the film grown on quartz displayed the phase transition at a lower\ntemperature (Tc=50C) compared a film grown on sapphire (Tc=68C). We also\ninvestigated differences in the detected Raman signal for different wavelengths\nand polarizations of the excitation laser. We found that for either substrate,\na longer wavelength (in our case 785 nm) yielded the clearest VO2 Raman\nspectra, with no polarization dependence.",
        "positive": "A structural path for the icosahedra <-> fcc structural transition in\n  clusters: We propose a structural path for the icosahedra <-> fcc transition in\nclusters and demonstrate the transition in Pb_13 by ab initio\nmolecular-dynamics simulation. The proposed path can be described by using only\ntwo variables. The energy surface on this two-dimensional space for Pb_13 was\ncalculated and a barrierless fcc-to-ico energy path was found. The atomic\ndisplacements of the proposed structural transition for ico and fcc Pb_13 were\nidentified as one of the vibrational eigenmodes of the clusters with a soft\nmode for fcc Pb_13. These agree with the energy curvatures around the two\nstructures, i.e. the ico Pb_13 is at the bottom of a valley on the energy\nsurface while the fcc Pb_13 is at a saddle point. The barriers of this\ntransition for larger clusters of Pb_n (n=55, 147 and 309) were also\ncalculated, by ab initio elastic-band method, and found being smaller than the\nroom-temperature thermal energy."
    },
    {
        "anchor": "Emergence of Rashba splitting and spin-valley properties in Janus\n  MoGeSiP2As2 and WGeSiP2As2 monolayers: First-principles calculations are performed to study the structural stability\nand spintronics properties of Janus MoGeSiP2As2 and WGeSiP2As2 monolayers. The\nhigh cohesive energies and the stable phonon modes confirm that both these\nstructures are experimentally accessible. In contrast to pristine MoSi2P4, the\nJanus monolayers demonstrate reduced direct bandgaps and large spin-split\nstates at K/-K. In addition, their spin textures exposed that breaking the\nmirror symmetry brings Rashba-type spin splitting in the systems which can be\nincreased by using higher atomic spin-orbit coupling. The large valley spin\nsplitting together with the Rashba splitting in these Janus monolayer\nstructures can make a remarkable contribution to semiconductor valleytronics\nand spintronics.",
        "positive": "Black phosphorus field-effect transistors: Two-dimensional crystals have emerged as a new class of materials with novel\nproperties that may impact future technologies. Experimentally identifying and\ncharacterizing new functional two-dimensional materials in the vast material\npool is a tremendous challenge, and at the same time potentially rewarding. In\nthis work, we succeed in fabricating field-effect transistors based on\nfew-layer black phosphorus crystals with thickness down to a few nanometers.\nDrain current modulation on the order of 10E5 is achieved in samples thinner\nthan 7.5 nm at room temperature, with well-developed current saturation in the\nIV characteristics, both are important for reliable transistor performance of\nthe device. Sample mobility is also found to be thickness dependent, with the\nhighest value up to ~ 1000 cm2/Vs obtained at thickness ~ 10 nm. Our results\ndemonstrate the potential of black phosphorus thin crystal as a new\ntwo-dimensional material for future applications in nano-electronic devices."
    },
    {
        "anchor": "ZnSnS3 : Structure Prediction, Ferroelectricity, and Solar Cell\n  Applications: The rapid growth of the solar energy industry has produced a strong demand\nfor high performance, efficient photoelectric materials. Many ferroelectrics,\ncomposed of earth-abundant elements, are useful for solar cell applications due\nto their large internal polarization. However, their wide band gaps prevent\nthem from absorbing light in the visible to mid-infrared range. Here, we\naddress the band gap issue by investigating, in particular, the substitution of\nsulphur for oxygen in the perovskite structure ZnSnO3 . Using evolutionary\nmethods we identify the stable and metastable structures of ZnSnS3 and compare\nthem to those previously characterized for ZnSnO3 . Our results suggest that\nZnSnS3 forms a monoclinic structure followed by metastable ilmenite and\nlithium-niobate structures. The latter structure is highly polarized and it\npossesses a significantly reduced band gap of 1.28 eV. These desirable\ncharacteristics make it a prime candidate for solar cell applications.",
        "positive": "Bi Incorporation and segregation in the MBE-grown\n  GaAs-(Ga,Al)As-Ga(As,Bi) core-shell nanowires: Incorporation of Bi into GaAs-(Ga,Al)As-Ga(As,Bi) core-shell nanowires grown\nby molecular beam epitaxy is studied with transmission electron microscopy.\nNanowires are grown on GaAs(111)B substrates with Au-droplet assisted mode.\nBi-doped shells are grown at low temperature (300 {\\deg}C) with a close to\nstoichiometric Ga/As flux ratio. At low Bi fluxes, the Ga(As,Bi) shells are\nsmooth, with Bi completely incorporated into the shells. Higher Bi fluxes\n(Bi/As flux ratio ~ 4%) led to partial segregation of Bi as droplets on the\nnanowires sidewalls, preferentially located at the nanowire segments with\nwurtzite structure. We demonstrate that such Bi droplets on the sidewalls act\nas catalysts for the growth of branches perpendicular to the GaAs trunks. Due\nto the tunability between zinc-blende and wurtzite polytypes by changing the\nnanowire growth conditions, this effect enables fabrication of branched\nnanowire architectures with branches generated from selected (wurtzite)\nnanowire segments."
    },
    {
        "anchor": "Nature of Ar bonding to small Co_n^+ clusters and its effect on the\n  structure determination by far-infrared absorption spectroscopy: Far-infrared vibrational spectroscopy by multiple photon dissociation has\nproven to be a very useful technique for the structural fingerprinting of small\nmetal clusters. Contrary to previous studies on cationic V, Nb and Ta clusters,\nmeasured vibrational spectra of small cationic cobalt clusters show a strong\ndependence on the number of adsorbed Ar probe atoms, which increases with\ndecreasing cluster size. Focusing on the series Co_4^+ to Co_8^+ we therefore\nuse density-functional theory to analyze the nature of the Ar-Co_n^+ bond and\nits role for the vibrational spectra. In a first step, energetically low-lying\nisomer structures are identified through first-principles basin-hopping\nsampling runs and their vibrational spectra computed for a varying number of\nadsorbed Ar atoms. A comparison of these fingerprints with the experimental\ndata enables in some cases a unique assignment of the cluster structure.\nIndependent of the specific low-lying isomer, we obtain a pronounced increase\nof the Ar binding energy for the smallest cluster sizes, which correlates\nnicely with the observed increased influence of the Ar probe atoms on the IR\nspectra. Further analysis of the electronic structure motivates a simple\nelectrostatic picture that not only explains this binding energy trend, but\nalso why the influence of the rare-gas atom is much stronger than in the\npreviously studied systems.",
        "positive": "Polymorphism of superionic ice: Water is abundant in natural environments but the form it resides in\nplanetary interiors remains uncertain. We report combined synchrotron X-ray\ndiffraction and optical spectroscopy measurements of H2O in the laser-heated\ndiamond anvil cell up to 150 gigapascals (GPa) and 6500 kelvin (K) that reveal\nfirst-order transitions to ices with body-centered cubic (bcc) and\nface-centered cubic (fcc) oxygen lattices above 900 (1300) K and 20 (29) GPa,\nrespectively. We assigned these structures to theoretically predicted\nsuperionic phases based on the distinct density, increased optical\nconductivity, and greatly decreased enthalpies of fusion. Our measurements\naddress current discrepancies between theoretical predictions and various\nstatic/dynamic experiments on the existence and location of melting curve and\nsuperionic phase(s) in the pressure-temperature phase diagram indicating a\npossible presence of the conducting fcc-superionic phase in water-rich giant\nplanets, such as Neptune and Uranus."
    },
    {
        "anchor": "Human-in-the-loop: The future of Machine Learning in Automated Electron\n  Microscopy: Machine learning methods are progressively gaining acceptance in the electron\nmicroscopy community for de-noising, semantic segmentation, and dimensionality\nreduction of data post-acquisition. The introduction of the APIs by major\ninstrument manufacturers now allows the deployment of ML workflows in\nmicroscopes, not only for data analytics but also for real-time decision-making\nand feedback for microscope operation. However, the number of use cases for\nreal-time ML remains remarkably small. Here, we discuss some considerations in\ndesigning ML-based active experiments and pose that the likely strategy for the\nnext several years will be human-in-the-loop automated experiments (hAE). In\nthis paradigm, the ML learning agent directly controls beam position and image\nand spectroscopy acquisition functions, and human operator monitors experiment\nprogression in real- and feature space of the system and tunes the policies of\nthe ML agent to steer the experiment towards specific objectives.",
        "positive": "Understanding Nanopore Window Distortions in the Reversible Molecular\n  Valve Zeolite RHO: Molecular valves are becoming popular for potential biomedical applications.\nHowever, little is known concerning their performance in energy and\nenvironmental areas. Zeolite RHO shows unique pore deformations upon changes in\nhydration, cation siting, cation type, or temperature-pressure conditions. By\nvarying the level of distortion of double eight-rings, it is possible to\ncontrol the adsorption properties, which confer a molecular valve behavior to\nthis material. We have employed interatomic potentials-based simulations to\nobtain a detailed atomistic view of the structural distortion mechanisms of\nzeolite RHO, in contrast with the averaged and space group restricted\ninformation provided by diffraction studies. We have modeled four\naluminosilicate structures, containing Li$^+$, Na$^+$, K$^+$, Ca$^{2+}$, and\nSr$^{2+}$ cations. The distortions of the three different zeolite rings are\ncoupled, and the six- and eight-membered rings are largely flexible. A large\ndependence on the polarizing power of the extra-framework cations and with the\nloading of water has been found for the minimum aperture of the eight-membered\nrings that control the nanovalve effect. The calculated energy barriers for\nmoving the cations across the eight-membered rings are very high, which\nexplains the experimentally observed slow kinetics of the phase transition as\nwell as the appearance of metastable phases."
    },
    {
        "anchor": "Internal Stresses and Formation of Switchable Nanowires at Thin Silica\n  Film Edge: At vertical edges, thin films of silicon oxide (SiO_{2-x}) contain\nsemiconductive c-Si layered nanocrystals (Si NC) embedded in and supported by\nan insulating g-SiO2 matrix. Tour et al. have shown that a trenched thin film\ngeometry enables the NC to form switchable nanowires (SNW) when trained by an\napplied field. The field required to form SNW decreases rapidly within a few\ncycles, or by annealing at 600 C in even fewer cycles, and is stable to 700C.\nHere we describe the intrinsic evolution of Si NC and SNW in terms of the\ncompetition between internal stresses and electro-osmosis. The analysis relies\nheavily on experimental data from a wide range of thin film studies, and it\nexplains why a vertical edge across the planar Si-SiOx interface is necessary\nto form SNW. The discussion also shows that the formation mechanisms of Si NC\nand Si/SiO_{2-x} SNW are intrinsic and result from optimization of nanowire\nconductivity in the presence of residual host misfit stresses.",
        "positive": "First-principles study of ferroelectric and antiferrodistortive\n  instabilities in tetragonal SrTiO3: We carry out first-principles density-functional calculations of the\nantiferrodistortive (AFD) and ferroelectric (FE) soft-mode instabilities in\ntetragonal SrTiO3, with the structural degrees of freedom treated in a\nclassical, zero-temperature framework. In particular, we use frozen-phonon\ncalculations to make a careful study of the anisotropy of the AFD and FE mode\nfrequencies in the tetragonal ground state, in which an R-point AFD soft phonon\nhas condensed. Because of the anharmonic couplings, the presence of this AFD\ndistortion substantially affects both the AFD and FE mode frequencies. The AFD\nmode is found to be softer for rotations around a perpendicular axis (Eg mode)\nthan for rotations about the tetragonal axis (A1g mode), in agreement with\nexperimental results. The FE mode, on the other hand, is found to be softer\nwhen polarized perpendicular to the tetragonal axis (Eu mode) than parallel to\nit (A2u mode). The sign of this frequency splitting is consistent with the\nexperimentally reported anisotropy of the dielectric susceptibility and other\nevidence. Finally, we present a discussion of the influence of various types of\nstructural distortions on the FE instability and its anisotropy."
    },
    {
        "anchor": "Topological States on the Gold Surface: Gold surfaces host special electronic states that have been understood as a\nprototype of Shockley surface states (SSs). These SSs are commonly employed to\nbenchmark the capability of angle-resolved photoemission spectroscopy (ARPES)\nand scanning tunneling spectroscopy. We find that these Shockley SSs can be\nreinterpreted as topologically derived surface states (TDSSs) of a topological\ninsulator (TI), a recently discovered quantum state. Based on band structure\ncalculations, the Z2 topological invariant can be well defined to characterize\nthe nontrivial features of gold that we detect by ARPES. The same TDSSs are\nalso recognized on surfaces of other well-known noble metals (e.g., silver,\ncopper, platinum, and palladium). Besides providing a new understanding of\nnoble metal SSs, finding topological states on late transition metals provokes\ninteresting questions on the role of topological effects in surface-related\nprocesses, such as adsorption and catalysis.",
        "positive": "Micromagnetic modeling of magnetization distribution caused by internal\n  twin microstructure of NiMnGa ferromagnetic shape memory alloys: In our present publication we will continue studying the effects of the\nmagnetostatic energy on the magnetization behavior of FMSMAs recently started\nin some our publications. Our method is based on the direct minimization of our\nnew micromagnetic free energy model of FMSMAs taking into account both the\nmagnetic anisotropy energy and the magnetostatic energy contributions\nassociated with the laminated two-variant twin microstructure. Here, our\nspecial interest is to investigate a distribution of local magnetizations\nwithin both twin variants, their orientation and their dependence on the\nexternal magnetic field and their volume fractions, as well."
    },
    {
        "anchor": "Mechanisms of enhanced orbital dia- and paramagnetism: Application to\n  the Rashba semiconductor BiTeI: We study the magnetic susceptibility of a layered semiconductor BiTeI with\ngiant Rashba spin splitting both theoretically and experimentally to explore\nits orbital magnetism. Apart from the core contributions, a large\ntemperature-dependent diamagnetic susceptibility is observed when the Fermi\nenergy E_F is near the crossing point of the conduction bands, while the\nsusceptibility turns to be paramagnetic when E_F is away from it. These\nfeatures are consistent with first-principles calculations, which also predict\nan enhanced orbital magnetic susceptibility with both positive and negative\nsigns as a function of E_F due to band (anti)crossings. Based on these\nobservations, we propose two mechanisms for an enhanced paramagnetic orbital\nsusceptibility.",
        "positive": "Planar Hall effect in type II Dirac semimetal VAl$_{3}$: The study of electronic properties in topological systems is one of the most\nfascinating topics in condensed matter physics, which has generated enormous\ninterests in recent times. New materials are frequently being proposed and\ninvestigated to identify their non-trivial band structure. While sophisticated\ntechniques such as angle-resolved photoemission spectroscopy have become\npopular to map the energy-momentum relation, the transport experiments lack any\ndirect confirmation of Dirac and Weyl fermions in a system. From band structure\ncalculations, VAl$_{3}$ has been proposed to be a type II topological Dirac\nsemimetal. This material represents a large family of isostructural compounds,\nall having similar electronic band structure and is an ideal system to explore\nthe rich physics of Lorentz symmetry violating Dirac fermions. In this work, we\npresent a detailed analysis on the magnetotransport properties of VAl$_{3}$. A\nlarge, non-saturating magnetoresistance has been observed. Hall resistivity\nreveals the presence of two types of charge carriers with high mobility. Our\nmeasurements show a large planar Hall effect in this material, which is robust\nand can be easily detectable up to high temperature. This phenomenon originates\nfrom the relativistic chiral anomaly and non-trivial Berry curvature, which\nvalidates the theoretical prediction of the Dirac semimetal phase in VAl$_{3}$."
    },
    {
        "anchor": "Magnetic structure determination from the magnetic pair distribution\n  function (mPDF): ground state of MnO: An experimental determination of the magnetic pair distribution function\n(mPDF) defined in an earlier paper (Frandsen, Yang, and Billinge. (2014) Acta\nCrystallogr. A, 70(1), 3-11) is presented for the first time. The mPDF was\ndetermined from neutron powder diffraction data from a reactor and a neutron\ntime-of-flight total scattering source on a powder sample of the\nantiferromagnetic oxide MnO. A description of the data treatment that allowed\nthe measured mPDF to be extracted and then modelled is provided and utilized to\ninvestigate the low-temperature structure of MnO. Atomic and magnetic\nco-refinements support the scenario of a locally monoclinic ground-state atomic\nstructure, despite the average structure being rhombohedral, with the magnetic\nPDF analysis successfully recovering the known antiferromagnetic spin\nconfiguration. The total scattering data suggest a preference for the spin axis\nto lie along the pseudocubic [10$\\bar{1}$] direction. Finally, $r$-dependent\nPDF refinements indicate that the local monoclinic structure tends toward the\naverage rhombohedral $R\\overline{3}m$ symmetry over a length scale of\napproximately 100~\\AA.",
        "positive": "Step-edge assisted large scale FeSe monolayer growth on epitaxial Bi2Se3\n  thin films: The interest in Fe-chalcogenide unconventional superconductors is intense\nafter the critical temperature of FeSe was reported enhanced by more than one\norder of magnitude in the monolayer limit at the interface to an insulating\noxide substrate. In heterostructures comprising interfaces of FeSe with\ntopological insulators, additional interesting physical phenomena is predicted\nto arise e.g. in form of {\\it topological superconductivity}. So far\nsuperconductive properties of Fe-chalcogenide monolayers were mostly studied by\nlocal scanning tunneling spectroscopy experiments, which can detect pseudo-gaps\nin the density of states as an indicator for Cooper pairing. Direct macroscopic\ntransport properties which can prove or falsify a superconducting phase were\nrarely reported due to the difficulty to grow films with homogeneous material\nproperties. Here we report on a promising growth method to fabricate continuous\ncarpets of monolayer thick FeSe on molecular beam epitaxy grown Bi$_2$Se$_3$\ntopological insulator thin films. In contrast to previous works using\natomically flat cleaved bulk Bi$_2$Se$_3$ crystal surfaces we observe a strong\ninfluence of the high step-edge density (terrace width about 10~nm) on\nMBE-grown Bi$_2$Se$_3$ substrates, which significantly promotes the growth of\ncoalescing FeSe domains with small tetragonal crystal distortion without\ncompromising the underlying Bi$_2$Se$_3$ crystal structure."
    },
    {
        "anchor": "A nexus between 3D atomistic data hybrids derived from atom probe\n  microscopy and computational materials science: a new analysis of solute\n  clustering in Al-alloys: Solute clusters affect the physical properties of alloys. Knowledge of the\natomic structure of solute clusters is a prerequisite for material\noptimisation. In this study, solute clusters in a rapid-hardening Al-Cu-Mg\nalloy were characterised by a combination of atom probe tomography and density\nfunctional theory, making use of a hybrid data type that combines lattice\nrectification and data completion to directly input experimental data into\natomistic simulations. The clusters input to the atomistic simulations are thus\nobserved experimentally, reducing the number of possible configurations. Our\nresults show that spheroidal, compact clusters are more energetically\nfavourable and more abundant.",
        "positive": "Understanding Controls on Interfacial Wetting at Epitaxial Graphene:\n  Experiment and Theory: The interaction of interfacial water with graphitic carbon at the atomic\nscale is studied as a function of the hydrophobicity of epitaxial graphene.\nHigh resolution X-ray reflectivity shows that the graphene-water contact angle\nis controlled by the average graphene thickness, due to the fraction of the\nfilm surface expressed as the epitaxial buffer layer whose contact angle\n(contact angle \\theta_c = 73{\\deg}) is substantially smaller than that of\nmultilayer graphene (\\theta_c = 93{\\deg}). Classical and ab initio molecular\ndynamics simulations show that the reduced contact angle of the buffer layer is\ndue to both its epitaxy with the SiC substrate and the presence of interfacial\ndefects. This insight clarifies the relationship between interfacial water\nstructure and hydrophobicity, in general, and suggests new routes to control\ninterface properties of epitaxial graphene."
    },
    {
        "anchor": "Design and Analysis of High Frequency InN Tunnel Transistors: This work reports the design and analysis of an n-type tunneling field effect\ntransistor based on InN. The tunneling current is evaluated from the\nfundamental principles of quantum mechanical tunneling and semiclassical\ncarrier transport. We investigate the RF performance of the device. High\ntransconductance of 2 mS/um and current gain cut-off frequency of around 460\nGHz makes the device suitable for THz applications. A significant reduction in\ngate to drain capacitance is observed under relatively higher drain bias. In\nthis regard, the avalanche breakdown phenomenon in highly doped InN junctions\nis analyzed quantitatively for the first time and is compared to that of Si and\nInAs.",
        "positive": "High-performance two-dimensional p-type transistors based on GaSe\n  layers: an ab-initio study: Ultrascaled GaSe field effect transistors are investigated through ab initio\ncalculations. GaSe monolayers, 3 nm long, exhibit excellent performance with\nreduced short-channel effects and considerable high ON-current. Such device\ncharacteristics are due to the valence band edge shape, which leads to very\nheavy holes in the transport direction and eventually suppresses intraband\ntunneling, detrimental for correct operation in the OFF state."
    },
    {
        "anchor": "Antisite effect on ferromagnetism in (Ga,Mn)As: We study the Curie temperature and hole density of (Ga,Mn)As while\nsystematically varying the As-antisite density. Hole compensation by\nAs-antisites limits the Curie temperature and can completely quench long-range\nferromagnetic order in the low doping regime of 1-2% Mn. Samples are grown by\nmolecular beam epitaxy without substrate rotation in order to smoothly vary the\nAs to Ga flux ratio across a single wafer. This technique allows for a\nsystematic study of the effect of As stoichiometry on the structural,\nelectronic, and magnetic properties of (Ga,Mn)As. For concentrations less than\n1.5% Mn, a strong deviation from Tc ~ p^0.33 is observed. Our results emphasize\nthat proper control of As-antisite compensation is critical for controlling the\nCurie temperatures in (Ga,Mn)As at the low doping limit.",
        "positive": "Manufacturing of Aluminum Composite Material Using Stir Casting Process: Manufacturing of aluminum alloy based casting composite materials via stir\ncasting is one of the prominent and economical route for development and\nprocessing of metal matrix composites materials. Properties of these materials\ndepend upon many processing parameters and selection of matrix and\nreinforcements. Literature reveals that most of the researchers are using 2, 6\nand 7xxx aluminum matrix reinforced with SiC particles for high strength\nproperties whereas, insufficient information is available on reinforcement of\n\"Al2O3\" particles in 7xxx aluminum matrix. The 7xxx series aluminum matrix\nusually contains Cu-Zn-Mg. Therefore, the present research was conducted to\ninvestigate the effect of elemental metal such as Cu-Zn-Mg in aluminum matrix\non mechanical properties of stir casting of aluminum composite materials\nreinforced with alpha \"Al2O3\" particles using simple foundry melting alloying\nand casting route. The age hardening treatments were also applied to study the\naging response of the aluminum matrix on strength, ductility and hardness. The\nexperimental results indicate that aluminum matrix cast composite can be\nmanufactured via conventional foundry method giving very good responses to the\nstrength and ductility up to 10% \"Al2O3\" particles reinforced in aluminum\nmatrix."
    },
    {
        "anchor": "Prediction of glass formability from liquid properties: Glass formation is one of the most interesting phenomena in the condensed\nmatter field. Considerable effort has gone into understanding and predicting\nthe glass formability. However, the previous prediction requires the glass\nfirst made before the prediction can be performed. Here, we propose a new\nprediction formula using liquid properties only. Moreover, we demonstrated that\nthe similarity between liquid and crystalline structure plays an important role\nin determine the glass formability. Previously, only the kinetics of nucleation\nand growth processes have been considered.",
        "positive": "Imaging of Spin Dynamics in Closure Domain and Vortex Structures: Time-resolved Kerr microscopy is used to study the excitations of individual\nmicron- scale ferromagnetic thin film elements in their remnant state. Thin (18\nnm) square elements with edge dimensions between 1 and 10 $\\mu$m form closure\ndomain structures with 90 degree Neel walls between domains. We identify two\nclasses of excitations in these systems. The first corresponds to precession of\nthe magnetization about the local demagnetizing field in each quadrant, while\nthe second excitation is localized in the domain walls. Two modes are also\nidentified in ferromagnetic disks with thicknesses of 60 nm and diameters from\n2 $\\mu$m down to 500 nm. The equilibrium state of each disk is a vortex with a\nsingularity at the center. As in the squares, the higher frequency mode is due\nto precession about the internal field, but in this case the lower frequency\nmode corresponds to gyrotropic motion of the entire vortex. These results\ndemonstrate clearly the existence of well-defined excitations in\ninhomogeneously magnetized microstructures."
    },
    {
        "anchor": "Zero Field precession and hysteretic threshold currents in spin torque\n  oscillators with tilted polarizer: Using non-linear system theory and numerical simulations we map out the\nstatic and dynamic phase diagram in zero applied field of a spin torque\noscillator with a tilted polarizer (TP-STO).We find that for sufficiently large\ncurrents, even very small tilt angles (beta>1 degree) will lead to steady free\nlayer precession in zero field. Within a rather large range of tilt angles, 1\ndegree< beta <19 degree, we find coexisting static states and hysteretic\nswitching between these using only current. In a more narrow window (1\ndegree<beta<5 degree) one of the static states turns into a limit cycle\n(precession). The coexistence of static and dynamic states in zero magnetic\nfield is unique to the tilted polarizer and leads to large hysteresis in the\nupper and lower threshold currents for TP-STO operation.",
        "positive": "Variational principle for magnetisation dynamics in a temperature\n  gradient: By applying a variational principle on a magnetic system within the framework\nof extended irreversible thermodynamics, we find that the presence of a\ntemperature gradient in a ferromagnet leads to a generalisation of the\nLandau-Lifshitz equation with an additional magnetic induction field\nproportional to the temperature gradient. This field modulates the damping of\nthe magnetic excitation. It can increase or decrease the damping, depending on\nthe orientation of the magnetisation wave-vector with respect to the\ntemperature gradient. This variational approach confirms the existence of the\nMagnetic Seebeck effect which was derived from thermodynamics and provides a\nquantitative estimate of the strength of this effect."
    },
    {
        "anchor": "The NaCl(100) Surface: Why Does it Not Melt?: The high temperature surface properties of alkali halide crystals are very\nunusual. Through molecular dynamics simulations based on Tosi-Fumi potentials,\nwe predict that crystalline NaCl(100) should remain stable without any\nprecursor signals of melting up to and even above the bulk melting point $T_m$.\nIn a metastable state, it should even be possible to overheat NaCl (100) by at\nleast 50 K. The reasons leading to this lack of surface self-wetting are\ninvestigated. We will briefly discuss the results of calculations of the\nsolid-vapor and liquid-vapor interface free energies, showing that the former\nis unusually low and the latter unusually high, and explaining why. Due to that\nthe mutual interaction among solid-liquid and liquid-vapor interfaces,\notherwise unknown, must be strongly attractive at short distance, leading to\nthe collapse of any liquid film attempting to nucleate at the solid surface.\nThis scenario naturally explains the large incomplete wetting angle of a drop\nof melt on NaCl(100).",
        "positive": "Free form three dimensional integrated circuits and wearables on a\n  thread using organic eutectogel gated electrochemical transistors: Existing flexible electronics are planar, nonbreathable, and easily damaged.\nIn this work, authors introduce a new paradigm of free-form three-dimensional\nintegrated circuits assembled on a single textile thread for ultimate\nflexibility. Transistors are assembled as daisy chain on a thread and utilize\ndeep eutectic solvent gels, or eutectogels as nonvolatile, breathable, and\nrepairable dielectric for gating organic electrochemical transistor. The\neutectogels provide stable transistor performance without the need for\nencapsulation, are air permeable to the skin, and make the Organic Eutectogel\nGated Electrochemical Transistor (OEGET) a promising candidate for wearable\nelectronics. Complex analog integrated circuits, such as single stage and\nmulti-stage amplifiers can be realized on a single thread which can bend out of\nthe plane of stretching for true three-dimensional flexibility. An all-thread\nbased wearable that uses a thread-based strain sensor and thread-based\nintegrated circuit for eye motion and respiration monitoring is also presented."
    },
    {
        "anchor": "Superconductors with anomalous Floquet higher-order topology: We develop a general theory for two-dimensional (2D) anomalous Floquet\nhigher-order topological superconductors (AFHOTSC), which are dynamical\nMajorana-carrying phases of matter with no static counterpart. Despite the\ntriviality of its bulk Floquet bands, an AFHOTSC generically features the\nsimultaneous presence of corner-localized Majorana modes at both zero and\n$\\pi/T$ quasi-energies, a phenomenon beyond the scope of any static topological\nband theory. We show that the key to AFHOTSC is its unavoidable singular\nbehavior in the phase spectrum of the bulk time-evolution operator. By mapping\nsuch evolution-phase singularities to the stroboscopic boundary signatures, we\nclassify all 2D AFHOTSCs that are protected by a rotation group symmetry in\nsymmetry class D. We further extract a higher-order topological index for\nunambiguously predicting the presence of Floquet corner Majorana modes, which\nwe confirm numerically. Our theory serves as a milestone towards a dynamical\ntopological theory for Floquet superconducting systems.",
        "positive": "Prediction of a Strain Induced Conduction Band Minimum in Embedded\n  Quantum Dots: Free standing InP quantum dots have previously been theoretically and\nexperimentally shown to have a direct band gap across a large range of\nexperimentally accessible sizes. We demonstrate that when these dots are\nembedded coherently within a GaP barrier material, the effects of quantum\nconfinement in conjunction with coherent strain suggest there will be a\ncritical diameter of dot (60A), above which the dot is direct, type I, and\nbelow which it is indirect, type II. However, the strain in the system acts to\nproduce another conduction state with an even lower energy, in which electrons\nare localized in small pockets at the interface between the InP dot and the GaP\nbarrier. Since this conduction state is GaP X_1c-derived and the highest\noccupied valence state is InP, Gamma-derived, the fundamental transition is\npredicted to be indirect in both real and reciprocal space (``type II'') for\nall dot sizes. This effect is peculiar to the strained dot, and is absent in\nthe free-standing dot."
    },
    {
        "anchor": "Thickness and strain effects on the thermoelectric transport in\n  nanostructured Bi2Se3: The structural stability, electronic structure, and thermal transport\nproperties of one to six quintuple layers (QLs) of Bi2Se3 are investigated by\nvan der Waals density functional theory and semi-classical Boltzmann theory.\nThe bandgap amounts to 0.41 eV for a single QL and reduces to 0.23 eV when the\nnumber of QLs increases to six. A single QL has a significantly higher\nthermoelectric figure of merit (0.27) than the bulk material (0.10), which can\nbe further enhanced to 0.30 by introducing 2.5% compressive strain. Positive\nphonon frequencies under strain indicate that the structural stability is\nmaintained.",
        "positive": "Controlling magnetism with light in a zero orbital angular momentum\n  antiferromagnet: Antiferromagnetic materials feature intrinsic ultrafast spin dynamics, making\nthem ideal candidates for future magnonic devices operating at THz frequencies.\nA major focus of current research is the investigation of optical methods for\nthe efficient generation of coherent magnons in antiferromagnetic insulators.\nIn magnetic lattices endowed with orbital angular momentum, spin-orbit coupling\nenables spin dynamics through the resonant excitation of low-energy electric\ndipoles such as phonons and orbital resonances which interact with spins.\nHowever, in magnetic systems with zero orbital angular momentum, microscopic\npathways for the resonant and low-energy optical excitation of coherent spin\ndynamics are lacking. Here, we consider experimentally the relative merits of\nelectronic and vibrational excitations for the optical control of zero orbital\nangular momentum magnets, focusing on a limit case: the antiferromagnet\nmanganese thiophoshate (MnPS3), constituted by orbital singlet Mn2+ ions. We\nstudy the correlation of spins with two types of excitations within its band\ngap: a bound electron orbital excitation from the singlet orbital ground state\nof Mn2+ into an orbital triplet state, which causes coherent spin precession,\nand a vibrational excitation of the crystal field that causes thermal spin\ndisorder. Our findings cast orbital transitions as key targets for magnetic\ncontrol in insulators constituted by magnetic centers of zero orbital angular\nmomentum."
    },
    {
        "anchor": "Hexagonal Boron Nitride-Graphene Heterostructures with Enhanced\n  Interfacial Thermal Conductance for Thermal Management Applications: Atomically thin monolayers of graphene show excellent electronic properties\nwhich have led to a great deal of research on their use in nanoscale devices.\nHowever, heat management of such nanoscale devices is essential in order to\nimprove their performance. Graphene supported on hexagonal boron nitride (h-BN)\nsubstrate has been reported to show enhanced (opto)electronic and thermal\nproperties as compared to extensively used SiO2/Si supported graphene.\nMotivated by this, we have performed temperature- and power-dependent Raman\nSpectroscopic measurements on four different types of (hetero)structures: (a)\nh-BN (BN), (b) graphene (Gr), (c) h-BN on graphene (BG), and (d) graphene\nencapsulated by h-BN layers from both top and bottom (BGB), all supported on\nSiO2/Si substrate. We have estimated the values of thermal conductivity\n(\\k{appa}) and interfacial thermal conductance per unit area (g) of these four\n(hetero)structures to demonstrate the structure-activity (thermal)\nrelationship. We report here the values of \\k{appa} and g for h-BN supported on\nSiO2/Si as 280.0\n  +-58.0 Wm-1K-1 and 25.6+-0.4 MWm-2K-1, respectively. More importantly, we\nhave observed an improvement in both thermal conductivity and interfacial\nthermal conductance per unit area in the heterostructures which ensures a\nbetter heat dissipation in devices. The \\k{appa} and g of h-BN encapsulated\ngraphene on SiO2/Si (BGB) sample was observed to be 850.0+-81.0 Wm-1K-1 and\n105+-1 MWm-2K-1, respectively, as opposed to 600.0+-93.0 Wm-1K-1 and 1.15+-0.40\nMWm-2K-1, respectively, for graphene on SiO2/Si substrate. Therefore, we\npropose that for graphene-based nanoscale devices, encapsulation with h-BN is a\nbetter alternative to address heat management issues.",
        "positive": "Ab initio explanation of disorder and off-stoichiometry in Fe-Mn-Al-C\n  kappa carbides: Carbides play a central role for the strength and ductility in many\nmaterials. Simulating the impact of these precipitates on the mechanical\nperformance requires the knowledge about their atomic configuration. In\nparticular, the C content is often observed to substantially deviate from the\nideal stoichiometric composition. In the present work, we focus on Fe-Mn-Al-C\nsteels, for which we determined the composition of the nano-sized kappa\ncarbides (Fe,Mn)3AlC by atom probe tomography (APT) in comparison to larger\nprecipitates located in grain boundaries. Combining density functional theory\nwith thermodynamic concepts, we first determine the critical temperatures for\nthe presence of chemical and magentic disorder in these carbides. Secondly, the\nexperimentally observed reduction of the C content is explained as a compromise\nbetween the gain in chemical energy during partitioning and the elastic strains\nemerging in coherent microstructures."
    },
    {
        "anchor": "Structural, optical and magnetic properties of nanostructured\n  Cr-substituted Ni-Zn spinel ferrites synthesized by a microwave combustion\n  method: Nanoparticles of Cr3+-substituted Ni-Zn ferrites with a general formula\nNi0.4Zn0.6-xCrxFe2O4 (x = 0.0 - 0.6) have been synthesized via a facile\nmicrowave combustion route. The crystalline phase has been characterized by\nXRD, TEM, FT-I and XPS revealing the spinel ferrite structure without extra\nphases. Crystallite sizes of 23 - 32 nm as estimated by XRD analyses, after\ncorrections for crystal stains by Williamson-Hall method, are comparable to the\naverage particle sizes observed by TEM which indicates successfully synthesized\nnanocrystals. Rietveld refinement analyses of the XRD patterns have inferred a\nmonotonic decrease behavior of the lattice parameter with Cr doping in\nagreement with Vegard's law of solid solution series. Furthermore, cations\ndistribution with an increased inversion factor indicate the B-site preference\nof Cr3+ ions. The oxidation states and cations distribution indicated by XPS\nresults imply the Cr3+ doping on the account of Zn2+ ions and a partial\nreduction of Fe3+ to Fe2+ to keep the charge balance in a composition series of\n(Ni2+)0.4(Zn2+, Cr3+)0.6(Fe2+, Fe3+)2(O2-)4. The optical properties were\nexplored by optical UV-Vis spectroscopy indicating allowed direct transitions\nwith band gap energy that decreases from 3.9 eV to 3.7 eV with Cr doping.\nFurthermore, the photocatalytic activity for the degradation of methyl orange\n(MO) dye was investigated showing largely enhanced photodecomposition up to 30%\nof MO dye over Ni0.4Cr0.6Fe2O4 for 6 hours. A vibrating sample magnetometry\n(VSM) measurements at room temperature show further enhancement in the\nsaturation magnetization of Ni0.4Zn0.6Fe2O4 , the highest in Ni-Zn ferrites,\nfrom about 60 to 70 emu/g with the increase of Cr concentration up to x = 0.1,\nwhile the coercivity shows a general increase in the whole range of Cr doping.",
        "positive": "Effect of nucleation sites on the growth and quality of single-crystal\n  boron arsenide: Boron arsenide (BAs) has been the least investigated cubic III-V compound,\nbut it has recently attracted significant attention since the confirmation of\nits unusually high thermal conductivity above 1000 W/m-K. However, determining\nhow to achieve growth of a BAs single crystal on the centimeter scale remains\nunsolved, which strongly limits further research into, and potential\napplications of, this interesting material. Here we report our technique to\ngrow a 7-mm-long BAs single crystal via the chemical vapor transport method by\napplying an additional nucleation site. The different thermal conductivity\nvalues obtained from BAs single crystals grown on nucleation sites of different\ncompositions show the importance of choosing the proper nucleation-site\nmaterial. We believe these findings will inspire further research into the\ngrowth of this unique semiconductor."
    },
    {
        "anchor": "Optical and mechanical properties of nanofibrillated cellulose: towards\n  a robust platform for next-generation green technologies: Nanofibrillated cellulose, a polymer that can be obtained from one of the\nmost abundant biopolymers in Nature, is being increasingly explored due to its\noutstanding properties for packaging and device applications. Still, open\nchallenges in engineering its intrinsic properties remain to address. The\nresults obtained show the precise determination of significant properties as\nelastic properties and interactions that are compared with similar works and,\nmoreover, demonstrate that nanofibrillated cellulose properties can be\nreversibly controlled, supporting the extended potential of nanofibrillated\ncellulose as a robust platform for green-technology applications",
        "positive": "Asymptotic near nucleus structure of the electron-interaction potential\n  in local effective potential theories: In local effective potential theories of electronic structure, the electron\ncorrelations due to the Pauli exclusion principle, Coulomb repulsion, and\ncorrelation-kinetic effects, are all incorporated in the local\nelectron-interaction potential $v_{ee}({\\bf r})$. In previous work, it has been\nshown that for spherically symmetric or sphericalized systems, the asymptotic\nnear nucleus expansion of this potential is $v_{ee}(r) = v_{ee}(0) + \\beta r +\nO(r^2)$, with $v_{ee}(0)$ being finite. By assuming that the Schr\\\"odinger and\nlocal effective potential theory wave functions are analytic near the nucleus\nof atoms, we prove the following via Quantal density functional theory (Q-DFT):\n(i) correlations due to the Pauli principle and Coulomb correlations do not\ncontribute to the linear structure; (ii) these Pauli and Coulomb correlations\ncontribute quadratically; (iii) the linear structure is {\\em solely} due to\ncorrelation-kinetic effects, the contributions of these effects being\ndetermined analytically. We also derive by application of adiabatic coupling\nconstant perturbation theory via Q-DFT (iv) the asymptotic near nucleus\nexpansion of the Hohenberg-Kohn-Sham theory exchange $v_x({\\bf r})$ and\ncorrelation $v_c({\\bf r})$ potentials. These functions also approach the\nnucleus linearly with the linear term of $v_x({\\bf r})$ being {\\em solely} due\nto the lowest-order correlation kinetic effects, and the linear term of\n$v_c({\\bf r})$ being due {\\em solely} to the higher-order correlation kinetic\ncontributions. The above conclusions are equally valid for systems of arbitrary\nsymmetry, provided spherical averages of the properties are employed."
    },
    {
        "anchor": "Mapping the energy surface of PbTiO3 in multidimensional\n  electric-displacement space: In recent years, methods have been developed that allow first-principles\nelectronic-structure calculations to be carried out under conditions of fixed\nelectric field. For some purposes, however, it is more convenient to work at\nfixed electric displacement field. Initial implementations of the\nfixed-displacement-field approach have been limited to constraining the field\nalong one spatial dimension only. Here, we generalize this approach to treat\nthe full three-dimensional displacement field as a constraint, and compute the\ninternal-energy landscape as a function of this multidimensional\ndisplacement-field vector. Using PbTiO3 as a prototypical system, we identify\nstable or metastable tetragonal, orthorhombic and rhombohedral structures as\nthe displacement field evolves along [001], [110] and [111] directions,\nrespectively. The energy minimum along [001] is found to be deeper than that\nalong [110] or [111], as expected for a system having a tetragonal ground\nstate. The barriers connecting these minima are found to be quite small,\nconsistent with the current understanding that the large piezoelectric effects\nin PbTiO3 arise from the easy rotation of the polarization vector.",
        "positive": "Spinodal Decomposition of Magnetic Ions in Eu-Codoped Ge/1-x/Cr/x/Te: We present the experimental evidence for the presence of spinodal\ndecomposition of the magnetic ions in the Ge/1-x-y/Cr/x/Eu/y/Te samples with\nchemical composition varying in the range of 0.015 < x < 0.057 and 0.003 < y <\n0.042. The ferromagnetic transition at temperatures 50 < T < 57 K was observed,\nindependent of the chemical composition. The long-range carrier mediated\nitinerant magnetic interactions seem to be responsible for the observed\nferromagnetic order. The magnetic irreversibility with coercive field H/C/ =\n5?63 mT and the saturation magnetization M/S/ <? 2?6 emu/g are found to\nstrongly depend on the chemical composition of the alloy."
    },
    {
        "anchor": "In-situ Atom Probe Deintercalation of Lithium-Manganese-Oxide: Atom probe tomography is routinely used for the characterisation of materials\nmicrostructures usually assuming that the microstructure is unaltered by the\nanalysis. When analysing ionic conductors, however, gradients in the chemical\npotential and the electric field penetrating dielectric atom probe specimens\ncan cause significant ionic mobility. While ionic mobility is undesired when\naiming for materials characterisation it offers a strategy to manipulate\nmaterials directly in-situ in the atom probe. Here, we present experimental\nresults on the analysis of the ionic conductor Lithium-Manganese-Oxide with\ndifferent atom probe techniques. We demonstrate that at a temperature of 30K\ncharacterisation of the materials microstructure is possible without measurable\nLi mobility. Contrary, we show that at 298K the material can be deintercalated\nin-situ in the atom probe without changing the Manganese-Oxide host structure.\nCombining in-situ atom probe deintercalation and subsequent conventional\ncharacterisation we demonstrate a new methodological approach to study ionic\nconductors even in early stages of deintercalation.",
        "positive": "Stochastic reconstruction of sandstones: A simulated annealing algorithm is employed to generate a stochastic model\nfor a Berea and a Fontainebleau sandstone with prescribed two-point probability\nfunction, lineal path function, and ``pore size'' distribution function,\nrespectively. We find that the temperature decrease of the annealing has to be\nrather quick to yield isotropic and percolating configurations. A comparison of\nsimple morphological quantities indicates good agreement between the\nreconstructions and the original sandstones. Also, the mean survival time of a\nrandom walker in the pore space is reproduced with good accuracy. However, a\nmore detailed investigation by means of local porosity theory shows that there\nmay be significant differences of the geometrical connectivity between the\nreconstructed and the experimental samples."
    },
    {
        "anchor": "Dirac energy spectrum and inverted band gap in metamorphic InAsSb/InSb\n  superlattices: A Dirac-type energy spectrum was demonstrated in gapless ultra-short-period\nmetamorphic InAsSb/InSb superlattices by angle-resolved photoemission\nspectroscopy (ARPES_ measurements. The Fermi velocity value 7.4x10^5 m/s in a\ngapless superlattice with a period of 6.2nm is in a good agreement with the\nresults of magneto-absorption experiments. An \"inverted\" bandgap opens in the\ncenter of the Brillouin zone at higher temperatures and in the SL with a larger\nperiod. The ARPES data indicate the presence of a surface electron accumulation\nlayer",
        "positive": "Rashba dominated spin-splitting in the bulk ferroelectric oxide\n  perovskite KIO3: The momentum-dependent Rashba and Dresselhaus spin-splitting has gained much\nattention for its highly promising applications in spintronics. In the present\nwork, ab initio density functional theory calculations are performed to study\nthe spin-splitting effect in ferroelectric oxide perovskite KIO3. Our\ncalculations are additionally supported by symmetry adapted two-band k.p\nHamiltonian. Non-negligible spin-splitting effect is observed at conduction\nband minimum (CBm) and valence band maximum (VBM) for rhombohedral R3m and R3c\nphases. Linear Rashba terms successfully explain the splitting at VBM. However,\ncubic terms become important in realizing spin-orientation near CBm. Our\nresults show the enhancement in Rashba parameters on tuning the ferroelectric\norder parameter. Further, we have observed reversal of spin-orientation on\nswitching the direction of polarization."
    },
    {
        "anchor": "Spin and recombination dynamics of excitons and free electrons in p-type\n  GaAs : effect of carrier density: Carrier and spin recombination are investigated in p-type GaAs of acceptor\nconcentration NA = 1.5 x 10^(17) cm^(-3) using time-resolved photoluminescence\nspectroscopy at 15 K. At low pho- tocarrier concentration, acceptors are mostly\nneutral and photoelectrons can either recombine with holes bound to acceptors\n(e-A0 line) or form excitons which are mostly trapped on neutral acceptors\nforming the (A0X) complex. It is found that the spin lifetime is shorter for\nelectrons that recombine through the e-A0 transition due to spin relaxation\ngenerated by the exchange scattering of free electrons with either trapped or\nfree holes, whereas spin flip processes are less likely to occur once the\nelectron forms with a free hole an exciton bound to a neutral acceptor. An\nincrease of exci- tation power induces a cross-over to a regime where the\nbimolecular band-to-band (b-b) emission becomes more favorable due to screening\nof the electron-hole Coulomb interaction and ionization of excitonic complexes\nand free excitons. Then, the formation of excitons is no longer possible, the\ncarrier recombination lifetime increases and the spin lifetime is found to\ndecrease dramatically with concentration due to fast spin relaxation with free\nphotoholes. In this high density regime, both the electrons that recombine\nthrough the e-A0 transition and through the b-b transition have the same spin\nrelaxation time.",
        "positive": "Effect of substrate temperature on the optoelectronic properties of DC\n  magnetron sputtered copper oxide films: Copper oxide thin films are deposited on quartz substrates by DC magnetron\nsputtering and the effect of deposition temperature on their optoelectronic\nproperties is examined in detail. Scanning Electron Microscopy (SEM), X-ray\ndiffraction (XRD) analysis, Raman spectroscopy, UV-Vis spectroscopy, and\nfour-probe sheet resistance measurements are used to characterize the surface\nmorphology, structural, optical, and electrical properties respectively.\nDeposition is carried out at room temperature and between 200 and 300 {\\deg}C.\nXRD analysis indicates that the oxide formed is primarily Cu$_2$O and the\nabsorption spectra show the films have a critical absorption edge at around 300\nnm. The sheet resistance gradually decreases with increase in deposition\ntemperature thereby increasing the conductivity of these thin films. Also\nobserved is the increase in band gap from 2.20 eV for room temperature\ndeposition to 2.35 eV at 300 {\\deg}C. The optical band gap and the variation of\nsheet resistance with temperature shows that the microstructure plays a vital\nrole in their behavior. These transformation characteristics are of huge\ntechnological importance having variety of applications including transparent\nsolar cell fabrication."
    },
    {
        "anchor": "Interface magnetism in Fe2O3/FeTiO3-heterostructures: To resolve the microscopic origin of magnetism in the Fe2O3/FeTiO3-system, we\nhave performed density functional theory calculations taking into account\non-site Coulomb repulsion. By varying systematically the concentration,\ndistribution and charge state of Ti in a hematite host, we compile a phase\ndiagram of the stability with respect to the end members and find a clear\npreference to form layered arrangements as opposed to solid solutions. The\ncharge mismatch at the interface is accommodated through Ti4+ and a\ndisproportionation in the Fe contact layer into Fe2+, Fe3+, leading to\nuncompensated moments in the contact layer and giving first theoretical\nevidence for the lamellar magnetism hypothesis. This interface magnetism is\nassociated with impurity levels in the band gap showing halfmetallic behavior\nand making Fe2O3/FeTiO3 heterostructures prospective materials for spintronics\napplications.",
        "positive": "Absence of topological Hall effect in Fe$_x$Rh$_{100-x}$ epitaxial\n  films: revisiting their phase diagram: A series of Fe$_x$Rh$_{100-x}$ ($30 \\leq x \\leq 57$) films were epitaxially\ngrown using magnetron sputtering, and were systematically studied by\nmagnetization-, electrical resistivity-, and Hall resistivity measurements.\nAfter optimizing the growth conditions, phase-pure Fe$_{x}$Rh$_{100-x}$ films\nwere obtained, and their magnetic phase diagram was revisited. The\nferromagnetic (FM) to antiferromagnetic (AFM) transition is limited at narrow\nFe-contents with $48 \\leq x \\leq 54$ in the bulk Fe$_x$Rh$_{100-x}$ alloys. By\ncontrast, the FM-AFM transition in the Fe$_x$Rh$_{100-x}$ films is extended to\ncover a much wider $x$ range between 33 % and 53 %, whose critical temperature\nslightly decreases as increasing the Fe-content. The resistivity jump and\nmagnetization drop at the FM-AFM transition are much more significant in the\nFe$_x$Rh$_{100-x}$ films with $\\sim$50 % Fe-content than in the Fe-deficient\nfilms, the latter have a large amount of paramagnetic phase. The\nmagnetoresistivity (MR) is rather weak and positive in the AFM state, while it\nbecomes negative when the FM phase shows up, and a giant MR appears in the\nmixed FM- and AFM states. The Hall resistivity is dominated by the ordinary\nHall effect in the AFM state, while in the mixed state or high-temperature FM\nstate, the anomalous Hall effect takes over. The absence of topological Hall\nresistivity in Fe$_{x}$Rh$_{100-x}$ films with various Fe-contents implies that\nthe previously observed topological Hall effect is most likely extrinsic. We\npropose that the anomalous Hall effect caused by the FM iron moments at the\ninterfaces nicely explains the hump-like anomaly in the Hall resistivity. Our\nsystematic investigations may offer valuable insights into the spintronics\nbased on iron-rhodium alloys."
    },
    {
        "anchor": "Stretching and breaking of chemical bonds, correlation of electrons, and\n  radical properties of covalent species: Chemical bonds are considered in light of correlation of valence electrons\nthat is strengthened when the bond is dissociated. In the framework of the\nunrestricted Hartree-Fock single-reference version of the configuration\ninteraction theory, effectively unpaired electrons lay the foundation of the\nelectron correlation measure in terms of total number of the electrons\n(molecular chemical susceptibility). graphs and their singularities with\nrespect to the interatomic distance allow presenting a quantitative description\nof stretching and breaking of chemical bonds. The approach validity is\ndemonstrated on a large number of bonds of different order and chemical\ncomposition.",
        "positive": "Surface zeta potential and diamond seeding on gallium nitride films: Measurement of zeta potential of Ga and N-face gallium nitride has been\ncarried out as function of pH. Both the faces show negative zeta potential in\nthe pH range 5.5-9. The Ga face has an isoelectric point at pH 5.5. The N-face\nshows higher negative zeta potential due to larger concentration of adsorbed\noxygen. Zeta potential data clearly showed that H-terminated diamond seed\nsolution at pH 8 will be optimal for the self assembly of a monolayer of\ndiamond nanoparticles on the GaN surface. Subsequent growth of thin diamond\nfilms on GaN seeded with H-terminated diamond seeds produced fully coalesced\nfilms confirming a seeding density in excess of 10$^{12}$ cm$^{-2}$. This\ntechnique removes the requirement for a low thermal conduction seeding layer\nlike silicon nitride on GaN."
    },
    {
        "anchor": "Crystal structures of spin-Jahn-Teller ordered MgCr_2O_4 and ZnCr_2O_4: Magnetic ordering in the geometrically frustrated magnetic oxide spinels\nMgCr_2O_4 and ZnCr_2O_4 is accompanied by a structural change that helps\nrelieve the frustration. Analysis of high-resolution synchrotron X-ray\nscattering reveals that the low-temperature structures are well described by a\ntwo-phase model of tetragonal I4_1/amd and orthorhombic Fddd symmetries. The\nCr_4 tetrahedra of the pyrochlore lattice are distorted at these\nlow-temperatures, with the Fddd phase displaying larger distortions than the\nI4_1/amd phase. The spin-Jahn-Teller distortion is approximately one order of\nmagnitude smaller than is observed in first-order Jahn-Teller spinels such as\nNiCr_2O_4 and CuCr_2O_4. In analogy with NiCr_2O_4 and CuCr_2O_4, we further\nsuggest that the precise nature of magnetic ordering can itself provide a\nsecond driving force for structural change.",
        "positive": "Analytical modeling of demagnetizing effect in magnetoelectric\n  ferrite/PZT/ferrite trilayers taking into account a mechanical coupling: In this paper, we investigate the demagnetizing effect in ferrite/PZT/ferrite\nmagnetoelectric (ME) trilayer composites consisting of commercial PZT discs\nbonded by epoxy layers to Ni-Co-Zn ferrite discs made by a reactive Spark\nPlasma Sintering (SPS) technique. ME voltage coefficients (transversal mode)\nwere measured on ferrite/PZT/ferrite trilayer ME samples with different\nthicknesses or phase volume ratio in order to highlight the influence of the\nmagnetic field penetration governed by these geometrical parameters.\nExperimental ME coefficients and voltages were compared to analytical\ncalculations using a quasi-static model. Theoretical demagnetizing factors of\ntwo magnetic discs that interact together in parallel magnetic structures were\nderived from an analytical calculation based on a superposition method. These\nfactors were introduced in ME voltage calculations which take account of the\ndemagnetizing effect. To fit the experimental results, a mechanical coupling\nfactor was also introduced in the theoretical formula. This reflects the\ndifferential strain that exists in the ferrite and PZT layers due to shear\neffects near the edge of the ME samples and within the bonding epoxy layers.\nFrom this study, an optimization in magnitude of the ME voltage is obtained.\nLastly, an analytical calculation of demagnetizing effect was conducted for\nlayered ME composites containing higher numbers of alternated layers (). The\nadvantage of such a structure is then discussed."
    },
    {
        "anchor": "Electric field control of phonon angular momentum in perovskite\n  BaTiO$_3$: We find that in BaTiO$_3$ the phonon angular momentum is dominantly pointing\nin directions perpendicular to the electrical polarization. Therefore, external\nelectric field in ferroelectric BaTiO$_3$ does not control only the direction\nof electrical polarization, but also the direction of phonon angular momentum.\nThis finding opens up the possibility for electric-field control of physical\nphenomena that rely on phonon angular momentum. We construct an intuitive\nmodel, based on our first-principles calculations, that captures the origin of\nthe relationship between phonon angular momentum and electric polarization.",
        "positive": "Finite-size effect of antiferromagnetic transition and electronic\n  structure in LiFePO4: The finite-size effect on the antiferromagnetic (AF) transition and\nelectronic configuration of iron has been observed in LiFePO4. Determination of\nthe scaling behavior of the AF transition temperature (TN) versus the\nparticle-size dimension (L) in the critical regime 1-TN(L)/TN(XTL)\\simL^-1\nreveals that the activation nature of the AF ordering strongly depends on the\nsurface energy. In addition, the effective magnetic moment that reflects the\nelectronic configuration of iron in LiFePO4 is found to be sensitive to the\nparticle size. An alternative structural view based on the polyatomic ion\ngroups of (PO4)3- is proposed."
    },
    {
        "anchor": "Exploring the Impact of Configurational Entropy on the Design and\n  Development of CoNi-Based Superalloys for Sustainable Applications: A comprehensive literature review on recently rediscovered Co- and/or\nCoNi-based superalloys, strengthened by the {\\gamma}' phase, revealed a\nrelationship between the configurational entropy of the system and the\n{\\gamma}' solvus temperature. This study was conducted on a high Cr CoNi-based\nsuperalloy system with high configurational entropy to test our hypothesis\nbased on the sustainable metallurgy framework. Thermodynamic calculations were\nperformed to design the chemical compositions, followed by vacuum casting and\nheat treatments to produce the desired alloys. The microstructures were\ncharacterized using a scanning electron microscope, electron backscattered\ndiffraction, transmission electron microscope, and differential thermal\nanalysis. Microhardness and nanoindentation tests were employed to measure the\nmechanical properties. The results showed that both the configurational entropy\nand the type of alloying elements determine the final high-temperature\nperformance of the alloys. We found that to enhance the higher {\\gamma}' solvus\ntemperature, the configurational entropy should be increased by adding\n{\\gamma}' stabilizing elements. The microstructural and mechanical\ncharacteristics of the designed alloys before and after heat treatments are\ndiscussed in detail. The outcome of this study is beneficial for developing\ncobalt-based high-entropy superalloys with appropriate processing windows and\nfreezing ranges for advanced sustainable manufacturing purposes, such as using\npowder bed fusion technologies.",
        "positive": "Monte-Carlo simulation of localization dynamics of excitons in ZnO and\n  CdZnO quantum well structures: Localization dynamics of excitons was studied for ZnO/MgZnO and CdZnO/MgZnO\nquantum wells (QW). The experimental photoluminescence (PL) and absorption data\nwere compared with the results of Monte Carlo simulation in which the excitonic\nhopping was modeled. The temperature-dependent PL linewidth and Stokes shift\nwere found to be in a qualitatively reasonable agreement with the hopping\nmodel, with accounting for an additional inhomogeneous broadening for the case\nof linewidth. The density of localized states used in the simulation for the\nCdZnO QW was consistent with the absorption spectrum taken at 5 K."
    },
    {
        "anchor": "Anisotropic Charge Distribution Induced by Spin Polarization in\n  La$_{0.6}$Sr$_{0.4}$MnO$_{3}$ Thin Films Studied by X-ray Magnetic Linear\n  Dichroism: Magnetic anisotropy of epitaxially grown thin films is affected by the strain\nfrom the substrates due to a combined effect of distorted electronic structure\nand spin-orbit interaction (SOI). As an inverse process, one expects an\nanisotropy of the electronic structure induced by magnetization in the presence\nof SOI. We have studied the charge-density anisotropy induced by magnetization\nin thin films of the ferromagnetic metal La$_{1-x}$Sr$_{x}$MnO$_3$ via x-ray\nmagnetic linear dichroism (XMLD). XMLD measurements on thin films with various\nthicknesses have shown that the XMLD intensity is proportional to the square of\nthe ferromagnetic moment. Using the XMLD sum rule and cluster-model\ncalculation, it has been shown that more Mn 3$d$ electrons are distributed in\norbitals elongated along the direction parallel to the spin polarization than\nin orbitals elongated in the direction perpendicular to it. The cluster-model\ncalculation has shown that the effect of tensile strain from the SrTiO$_3$\nsubstrate on the XMLD spectra is also consistent with the observed XMLD\nspectral line shapes.",
        "positive": "Topological insulator Bi2Se3 films on rare earth iron garnets and their\n  high-quality interfaces: The integration of quantum materials like topological insulators (TIs) with\nmagnetic insulators (MIs) has important technological implications for\nspintronics and quantum computing. Here we report excellent crystallinity of\nc-axis oriented epitaxial TI films Bi2Se3 grown on MI films, a rare earth iron\ngarnet (ReIG), such as thulium iron garnet (Tm3Fe5O12, TmIG) by molecular beam\nepitaxy (MBE) with a Se-buffered low-temperature (SBLT) growth technique. We\ndemonstrated a streaky reflection high-energy electron diffraction pattern\nstarting from the very first quintuple layer of Bi2Se3, indicating the\nhigh-quality interface between TmIG and Bi2Se3, a prerequisite for studying\ninterfacial exchange coupling effects. The strong interfacial exchange\ninteraction was manifested by observations of anomalous Hall effect in the\nBi2Se3/TmIG bilayer and a shift of ferromagnetic resonance field of TmIG\ninduced by Bi2Se3. We have reproducibly grown high-quality Bi2Se3/ReIG and\ninterfaces using this new TI growth method, which may be applied to grow other\ntypes of van der Waals (vdW) hetero-structures."
    },
    {
        "anchor": "Strain-controlled fundamental gap and structure of bulk black phosphorus: We study theoretically the structural and electronic response of layered bulk\nblack phosphorus to in-layer strain. Ab initio density functional theory (DFT)\ncalculations reveal that the strain energy and interlayer spacing display a\nstrong anisotropy with respect to the uniaxial strain direction. To correctly\ndescribe the dependence of the fundamental band gap on strain, we used the\ncomputationally more involved GW quasiparticle approach that is free of\nparameters and superior to DFT studies, which are known to underestimate gap\nenergies. We find that the band gap depends sensitively on the in-layer strain\nand even vanishes at compressive strain values exceeding about 2%, thus\nsuggesting a possible application of black P in strain-controlled infrared\ndevices.",
        "positive": "Temperature-Dependent Diffuse Reflectance Measurements of Ceramic\n  Powders in the Near- and Mid-Infrared Spectra: This study focuses on experimentally measuring temperature-dependent diffuse\nreflectance in the near- and mid-infrared spectra for ceramic particles with\napplications as heat-transfer and thermal-storage media in concentrated solar\npower (CSP) plants. Specifically, a commercially available sintered bauxite\nceramic powder, ACCUCAST ID80, and its primary chemical constituents, alumina\n(Al2O3) and silica (SiO2), are measured using a Fourier transform infrared\nspectrometer (FTIR) coupled with a specialized diffuse reflectance accessory\nand a heated stage. Room-temperature diffuse reflectance measurements show\nincreased absorption in tests with greater mass fractions of the ceramic\nsamples. There is a strong correlation in the measured reflectance spectra of\nACCUCAST with alumina and silica in the spectral range 2000-500 cm-1. For the\nfirst time, temperature-dependent diffuse reflectance measurements are reported\nfor ACCUCAST, including a novel technique for accessing reflectance values\nabove the limiting temperature of the background material KBr. All three\nmaterials exhibit a calculated emittance of ~0.9 at room temperature. However,\nthis value drops to 0.68 at 1000 C for ACCUCAST and ~0.43 for alumina and\nsilica. Thermal cycling in air from 25 C to 1000 C resulted in a visible color\nchange from dark grey to light orange for ACCUCAST and a subsequent 5X greater\nincrease in reflectance at 4000 cm-1 as compared to ACCUCAST thermally cycled\nat 1000 C in vacuum. Alumina and silica spectra proved to be largely unaffected\nby thermal cycling under atmospheric and evacuated conditions."
    },
    {
        "anchor": "Lifetimes of Shockley electrons and holes at the Cu(111) surface: A theoretical many-body analysis is presented of the electron-electron\ninelastic lifetimes of Shockley electrons and holes at the (111) surface of Cu.\nFor a description of the decay of Shockley states both below and above the\nFermi level, single-particle wave functions have been obtained by solving the\nSchr\\\"odinger equation with the use of an approximate one-dimensional\npseudopotential fitted to reproduce the correct bulk energy bands and\nsurface-state dispersion. A comparison with previous calculations and\nexperiment indicates that inelastic lifetimes are very sensitive to the actual\nshape of the surface-state single-particle orbitals beyond the $\\bar\\Gamma$\n(${\\bf k}_\\parallel=0$) point, which controls the coupling between the Shockley\nelectrons and holes.",
        "positive": "Characterization of the 2D Su-Schrieffer-Heeger Model with\n  Second-Nearest-Neighbor Interactions: It is known that a two dimensional dimerized Su-Schrieffer-Heeger model can\nproduce a nontrivial topological phase. It is a simple nearest-neighbor model\nwith either two or four lattice sites in in two dimensions.\nSu-Schrieffer-Heeger model is easy to analyse but neglects important\ninteraction in physical systems. In this work, an extended version of this\nmodel is proposed which includes all possible second nearest neighbor\ninteractions in order to make it more feasible to describe realistic systems.\nThe topological phases and properties of the model are characterized using a\npolarization invariant. It is further shown that second nearest neighbor\ninteractions can be used to evoke a topological phase transition as well."
    },
    {
        "anchor": "Raman and first-principles study of the pressure induced Mott-insulator\n  to metal transition in bulk FePS$_3$: Recently discovered class of 2D materials based on transition metal\nphosphorous trichalcogenides exhibit antiferromagnetic ground state, with\npotential applications in spintronics. Amongst them, FePS$ _{3} $ is a Mott\ninsulator with a band gap of $\\sim$ 1.5 eV. This study using Raman spectroscopy\nalong with first-principles density functional theoretical analysis examines\nthe stability of its structure and electronic properties under pressure. Raman\nspectroscopy reveals two phase transitions at 4.6 GPa and 12 GPa marked by the\nchanges in pressure coefficients of the mode frequencies and the number of\nsymmetry allowed modes. FePS$_3$ transforms from the ambient monoclinic C2/m\nphase with a band gap of 1.54 eV to another monoclinic C2/m (band gap of 0.1\neV) phase at 4.6 GPa, followed by another transition at 12 GPa to the metallic\ntrigonal P-31m phase. Our work complements recently reported high pressure\nX-ray diffraction studies.",
        "positive": "Stable ferromagnetism and doping induced half-metallicity in asymmetric\n  graphene nanoribbons: We propose a class of graphene nanoribbons showing strong intrinsic\nferromagnetic behavior due to their asymmetry. Such ribbons are based on a\nzig-zag edged backbone surmounted by a periodic, triangular notched region of\nvariable size. The electronic properties as a function of the topology are\ninvestigated. Interestingly, substitutional doping by boron or nitrogen induces\nhalf-metallicity. The most effective doping sites can be inferred from the band\nstructure. Given the present rapid development of bottom-up strategies for the\nsynthesis of atomically precise carbon nanostructures the proposed class of\nnanoribbons emerges as a real candidate for spintronic applications at ambient\ntemperature."
    },
    {
        "anchor": "An Improved Description of the Dielectric Breakdown in Oxides Based on a\n  Generalized Weibull distribution: In this work, we address modal parameter fluctuations in statistical\ndistributions describing charge-to-breakdown $(Q_{BD})$ and/or\ntime-to-breakdown $(t_{BD})$ during the dielectric breakdown regime of\nultra-thin oxides, which are of high interest for the advancement of electronic\ntechnology. We reobtain a generalized Weibull distribution ($q$-Weibull), which\nproperly describes $(t_{BD})$ data when oxide thickness fluctuations are\npresent, in order to improve reliability assessment of ultra-thin oxides by\ntime-to-breakdown $(t_{BD})$ extrapolation and area scaling. The incorporation\nof fluctuations allows a physical interpretation of the $q$-Weibull\ndistribution in connection with the Tsallis statistics. In support to our\nresults, we analyze $t_{BD}$ data of SiO$_2$-based MOS devices obtained\nexperimentally and theoretically through a percolation model, demonstrating an\nadvantageous description of the dielectric breakdown by the $q$-Weibull\ndistribution.",
        "positive": "Perspective: Molecular beam epitaxy of antiperovskite oxides: Antiperovskites, or inverse perovskites, have recently emerged as a material\nclass with a plethora of promising electronic properties. This perspective\ndescribes the molecular beam epitaxy (MBE) growth of oxide antiperovskites\nSr$_3$PbO and Sr$_3$SnO. We show that MBE offers great potential not only in\ngrowing antiperovskites with high structural quality, but also in providing a\nmeans to seamlessly connect with advanced characterization tools, including\nx-ray photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED),\nreflection high-energy electron diffraction (RHEED), and scanning tunneling\nmicroscopy (STM), to facilitate the analyses of their intrinsic properties. The\ninitial results point toward the feasibility of atomically controlled\nantiperovskite growth, which could open doors to study topological and\ncorrelated electronic states in an electronic environment quite distinct from\nwhat is available in conventional complex oxides."
    },
    {
        "anchor": "Electrically detected paramagnetic resonance in Ag-paint coated DPPH: We describe a simple experimental method to detect electron paramagnetic\nresonance (EPR) in polycrystalline 2,2-diphenyl-1-picrylhydrazyl (DPPH) sample,\nthe standard g-marker for EPR spectroscopy, without using a cavity resonator or\na prefabricated waveguide. It is shown that microwave(MW) current injected into\na layer of silver paint coated on an insulating DPPH sample is able to excite\nthe paramagnetic resonance in DPPH. As the applied dc magnetic field H is\nswept, the high-frequency resistance of the Ag-paint layer, measured at room\ntemperature with a single port impedance analyzer in the MW frequency range 1\nto 2.5 GHz, exhibits a sharp peak at a critical value of the dc field (H =\nHres) while the reactance exhibits a dispersion-like behavior around the same\nfield value for a given frequency. Hres increases linearly with the frequency\nof MW current. We interpret the observed features in the impedance to EPR in\nDPPH driven by the Oersted magnetic field arising from the MW current in the\nAg-paint layer. We also confirm the occurrence of EPR in DPPH independently\nusing a coplanar waveguide-based broadband technique. This technique has the\npotential to investigate other EPR active inorganic and organic compounds.",
        "positive": "Flat Dielectric Response in 3BaO-3TiO2-B2O3 Glasses: X-ray powder diffraction (XRD) along with differential thermal analysis (DTA)\ncarried out on the as-quenched samples in the 3BaO-3TiO2-B2O3 system confirmed\ntheir amorphous and glassy nature, respectively. The dielectric constants in\nthe 1 kHz-1 MHz frequency range were measured as a function of temperature\n(323-748 K). The dielectric constant and loss were found to be frequency\nindependent in the 323-473 K temperature range. The dielectric behavior was\nconsistent with the universal dielectric response (UDR). The temperature\ncoefficient of dielectric constant was estimated using Havinga's formula and\nfound to be 16 ppm.K-1. The electrical relaxation was rationalized using the\nelectric modulus formalism. The dielectric constant and loss were 17 \\pm 0.5\nand 0.005 \\pm 0.001, respectively at 323 K in the 1 kHz-1 MHz frequency range\nwhich may be of considerable interest to capacitor industry."
    },
    {
        "anchor": "Stuffed Rare Earth Garnets: We report the synthesis and magnetic characterization of stuffed rare earth\ngallium garnets, RE3+xGa5-xO12 (RE=Lu, Yb, Er, Dy, Gd), for x up to 0.5. The\nexcess rare earth ions partly fill the octahedral sites normally fully occupied\nby Ga3+, forming disordered pairs of corner-shared face-sharing magnetic\ntetrahedra. The Curie-Weiss constants and observed effective moments per rare\nearth are smaller than are seen for the unstuffed gallium garnets. No\nsignificant change in the field-dependent magnetization is observed but missing\nentropy is seen when integrating the low-temperature heat capacity to 0.5 K.",
        "positive": "Computational insights and the observation of SiC nanograin assembly:\n  towards 2D silicon carbide: While an increasing number of two-dimensional (2D) materials, including\ngraphene and silicene, have already been realized, others have only been\npredicted. An interesting example is the two-dimensional form of silicon\ncarbide (2D-SiC). Here, we present an observation of atomically thin and\nhexagonally bonded nanosized grains of SiC assembling temporarily in graphene\noxide pores during an atomic resolution scanning transmission electron\nmicroscopy experiment. Even though these small grains do not fully represent\nthe bulk crystal, simulations indicate that their electronic structure already\napproaches that of 2D-SiC. This is predicted to be flat, but some doubts have\nremained regarding the preference of Si for sp$^{3}$ hybridization. Exploring a\nnumber of corrugated morphologies, we find completely flat 2D-SiC to have the\nlowest energy. We further compute its phonon dispersion, with a Raman-active\ntransverse optical mode, and estimate the core level binding energies. Finally,\nwe study the chemical reactivity of 2D-SiC, suggesting it is like silicene\nunstable against molecular absorption or interlayer linking. Nonetheless, it\ncan form stable van der Waals-bonded bilayers with either graphene or hexagonal\nboron nitride, promising to further enrich the family of two-dimensional\nmaterials once bulk synthesis is achieved."
    },
    {
        "anchor": "Ground state structure of BaFeO$_{3}$: Density Functional Theory\n  Calculations: Using density functional theory calculations, the ground state structure of\nBaFeO$_3$ (BFO) is investigated with local spin density approximation (LSDA).\nCubic, tetragonal, orthorhombic, and rhombohedral types BFO are considered to\ncalculate the formation enthalpy. The formation enthalpies reveal that cubic is\nthe most stable structure of BFO. Small energy difference between the cubic and\ntetragonal suggests a possible tetragonal BFO. Ferromagnetic(FM) and\nanitiferromagnetic (AFM) coupling between the Fe atoms show that all the\nstriochmetric BFO are FM. The energy difference between FM and AFM shows room\ntemperature ferromagnetism in cubic BFO in agreement with the experimental\nwork. The LSDA calculated electronic structures are metallic in all studied\ncrystallographic phases of BFO. Calculations including the Hubbard potential\n$U,i.e.$ LSDA+$U$, show that all phases of BFO are half-metallic consistent\nwith the integer magnetic moments. The presence of half-metallicity is\ndiscussed in terms of electronic band structures of BFO.",
        "positive": "Vibrational Spectra of MO (M=Sn/Pb) in Their Bulk and Single Layer\n  Forms: Role of Avoided Crossing in their Thermodynamic Properties: We report ab-initio calculations of the phonon dispersion relation on the\nbulk and single layer of SnO and PbO. We identify Raman active modes and\ninfrared active modes at the zone center {\\Gamma} point. In agreement with\nexperimental observations of Raman spectroscopy measurement, we find that A1g\nmode is higher in frequency than that of Eg mode. Moreover, the reason behind\nthe shift of A2u mode to higher frequency for monolayer of both SnO and PbO is\nrevealed from our calculations. We also find that long-range Coulomb\ninteraction enhances the dielectric constant and Born effective charges in bulk\nSnO and bulk PbO, compared to their monolayer. Here, we observe avoided\ncrossing or Landau degeneracy between longitudinal acoustics (LA) and low\nenergetic transverse optical (TO) modes in bulk form of both SnO and PbO.\nAdditionally, monolayer SnO also shows low energetic Raman modes (Eg and A1g)\nof same frequency as bulk. As a result, we notice avoided crossing between LA\nand TO modes in monolayer SnO. Interestingly, higher Born effective charge and\nlow dielectric constant enhances self-force constants and the interatomic force\nconstants (IFCs) between the M-O bonds. The enhanced force constants give rise\nto higher vibrational frequency of phonon modes for monolayer PbO. Our studies\nreveal that due to avoided crossing between two degenerate bands, the phonon\ndispersion near high symmetry X point lowers specific heat and vibrational\nentropy in bulk SnO, bulk PbO and only in monolayer SnO upto temperature 150 K.\nMoreover, the large mass difference between Pb and Oxygen atoms and absence of\ninterlayer van der Waal interactions give rise to high phonon vibration which\nreduces the occurrence of band crossing between two degenerate energy levels.\nThe absence of avoided crossing leads higher specific heat and vibrational\nentropy in monolayer PbO at low temperatures."
    },
    {
        "anchor": "Ytterbium divalency and lattice disorder in near-zero thermal expansion\n  YbGaGe: While near-zero thermal expansion (NZTE) in YbGaGe is sensitive to\nstoichiometry and defect concentration, the NZTE mechanism remains elusive. We\npresent x-ray absorption spectra that show unequivocally that Yb is nearly\ndivalent in YbGaGe and the valence does not change with temperature or with\nnominally 1% B or 5% C impurities, ruling out a valence-fluctuation mechanism.\nMoreover, substantial changes occur in the local structure around Yb with B and\nC inclusion. Together with inelastic neutron scattering measurements, these\ndata indicate a strong tendency for the lattice to disorder, providing a\npossible explanation for NZTE in YbGaGe.",
        "positive": "Magnetomechanical effects in the elastic polymer composites containing\n  different volume fraction of ferromagnetic powder particles: In the present work a detailed thermodynamic consideration for the magnetic\nfree energy of the composite material consisting of the ferromagnetic powder\nparticles embedded into a polymer matrix is given. We estimate their\nmagnetostatic interaction energy and its dependence on the microscopic\ndistribution of the magnetization and the magnetic field in the composite\nmaterial. We also define the hydrostatic component of the mechanical force\ndeveloped and the volume change effect caused by the magnetostatic interactions\nin such composites."
    },
    {
        "anchor": "Switching magnetization of nano-scale ferromagnetic particle using\n  non-local spin injection: We have performed non-local spin injection into a nano-scale ferromagnetic\nparticle configured in a lateral spin valve structure to switch its\nmagnetization only by spin current. The non-local spin injection aligns the\nmagnetization of the particle parallel to the magnetization of the spin\ninjector. The responsible spin current for switching is estimated from the\nexperiment to be about 200 $\\mu$A, which is reasonable compared with the values\nobtained for conventional pillar structures. Interestingly the switching always\noccurs from anti-parallel to parallel in the particle/injector magnetic\nconfigurations, whereas no opposite switching is observed. Possible reasons for\nthis discrepancy are discussed.",
        "positive": "Diffusion processes in germanium and silicon films grown on Si$_3$N$_4$\n  substrates: In this article, the results of investigation of processes occurring during\nthe molecular-beam deposition of germanium layers on Si$_3$N$_4$ dielectric\nsubstrates within a wide range of the Ge film growth temperatures (30 to\n600{\\deg}C) are presented. The intensity of the IR absorption bands related to\nthe vibrations of the N$-$H and Si$-$N bonds are established to decrease with\nthe increase of the Ge deposition temperature. It appears that this phenomenon\ncannot be explained only as a thermally activated process. Simultaneously, the\npeak corresponding to the Ge$-$N vibration bonds emerges in the X-ray\nphotoelectron spectra. We suppose that the deposition of germanium layers on\nSi3N4 dielectric substrates containing hydrogen atoms causes the diffusion of\nhydrogen atoms from the dielectric layer into the growing film. The\nexperimental results may be interpreted in terms of a model, according to which\nthe migration of hydrogen atoms from the Si$_3$N$_4$ layer into the growing\ngermanium film is due to the difference in chemical potentials of hydrogen\natoms in the dielectric layer and the germanium film. This process initiates\nthe diffusion of germanium atoms in the opposite direction, into the\nSi$_3$N$_4$ layer, where they connect to free bonds of nitrogen atoms arising\ndue to the escape of hydrogen atoms. The analogous processes occur during the\ndeposition of silicon layers on Si$_3$N$_4$ substrates."
    },
    {
        "anchor": "Modification of poly(L-lactide) and polycaprolactone bioresorbable\n  polymeric materials by RF plasma discharge: a preliminary study evaluating\n  EA-hy 926 cell attachment: Surface modification of poly(L-lactide) (L-PLA) and polycaprolactone (PCL)\nbioresorbable polymers by radio-frequency thermal glow discharge plasma is\nreported. Improved biocompatibility of L-PLA and PCL materials was obtained by\nemploying hydroxyapatite target sputtering in Ar+ plasma as evidenced by the\nchange of L-PLA and PCL properties from highly hydrophobic to hydrophilic, with\nabsolute wettability obtained for both materials, and enhanced endothelial\nhybrid cell line EA-hy 926 attachment to modified surfaces. For the latter,\nsurface properties that suppress adverse cellular responses (e.g. apoptosis,\nnecrosis) were also attained. Surface roughness and surface free energy were\nfound to increase significantly for both polymers under prolonged plasma\nexposure and, a longer chain aliphatic PCL were found to display a marginally\nbetter post plasma-treated biocompatibility compared to L-PLA.",
        "positive": "Excitations in time-dependent density-functional theory: An approximate solution to the time-dependent density functional theory\n(TDDFT) response equations for finite systems is developed, yielding\ncorrections to the single-pole approximation. These explain why allowed\nKohn-Sham transition frequencies and oscillator strengths are usually good\napproximations to the true values, and why sometimes they are not. The\napproximation yields simple expressions for G\\\"orling-Levy perturbation theory\nresults, and a method for estimating expectation values of the unknown\nexchange-correlation kernel."
    },
    {
        "anchor": "Long-term stability of phase-separated Half-Heusler compounds: Half-Heusler (HH) compounds have shown high Figure of merits up to 1.5. The\nkey to these high thermoelectric efficiencies is an intrinsic phase separation,\nwhich occurs in multicomponent Half-Heusler compounds and leads to an\nsignificantly reduction of the thermal conductivity. For commercial\napplications, compatible n- and p-type materials are essential and their\nthermal stability under operating conditions, e.g. for an automotive up to 873\nK, needs to be guaranteed. For the first time, the long-term stability of n-\nand p-type HH materials is proved. We investigated HH materials based on the\nTi0.3Zr0.35Hf0.35NiSn-system after 500 cycles (1700 h) from 373 to 873 K. Both\ncompounds exhibit a maximum Seebeck coefficient of S around 210 muV/K and an\nintrinsic phase separation into two HH phases. The dendritic microstructure is\ntemperature resistant and maintained the low thermal conductivity values (kappa\nless than 4 W/Km). Our results emphasize that phase-separated HH compounds are\nsuitable low cost materials and can lead to enhanced thermoelectric\nefficiencies beyond the set benchmark for industrial applications.",
        "positive": "Full control of solid-state electrolytes for electrostatic gating: Ionic gating is a powerful technique to realize field-effect transistors\n(FETs) enabling experiments not possible otherwise. So far, ionic gating has\nrelied on the use of top-electrolyte gates, which pose experimental constraints\nand make device fabrication complex. Promising results obtained recently in\nFETs based on solid-state electrolytes remain plagued by spurious phenomena of\nunknown origin, preventing proper transistor operation, and causing limited\ncontrol and reproducibility. Here we explore a class of solid-state\nelectrolytes for gating (Lithium-ion conducting glass-ceramics, LICGCs),\nidentify the processes responsible for the spurious phenomena and\nirreproducible behavior,and demonstrate properly functioning transistors\nexhibiting high density ambipolar operation with gate capacitance of ~20-50\n$\\mu$F/cm$^2$ (depending on the polarity of the accumulated charges). Using\ntwo-dimensional semiconducting transition-metal dichalcogenides we demonstrate\nthe ability to implement ionic-gate spectroscopy to determine the\nsemiconducting bandgap, and to accumulate electron densities above 10$^{14}$\ncm$^{-2}$, resulting in gate-induced superconductivity in MoS$_2$ multilayers.\nAs LICGCs are implemented in a back-gate configuration, they leave the surface\nof the material exposed, enabling the use of surface-sensitive techniques (such\nas scanning tunneling microscopy and photoemission spectroscopy) impossible so\nfar in ionic-liquid gated devices. They also allow double ionic gated devices\nproviding independent control of charge density and electric field."
    },
    {
        "anchor": "Neighbors Map: an Efficient Atomic Descriptor for Structural Analysis: Accurate structural analysis is essential to gain physical knowledge and\nunderstanding of atomic-scale processes in materials from atomistic\nsimulations. However, traditional analysis methods often reach their limits\nwhen applied to crystalline systems with thermal fluctuations, defect-induced\ndistortions, partial vitrification, etc. In order to enhance the means of\nstructural analysis, we present a novel descriptor for encoding atomic\nenvironments into 2D images, based on a pixelated representation of graph-like\narchitecture with weighted edge connections of neighboring atoms. This\ndescriptor is well adapted for Convolutional Neural Networks and enables\naccurate structural analysis at a low computational cost. In this paper, we\nshowcase a series of applications, including the classification of crystalline\nstructures in distorted systems, tracking phase transformations up to the\nmelting temperature, and analyzing liquid-to-amorphous transitions in pure\nmetals and alloys. This work provides the foundation for robust and efficient\nstructural analysis in materials science, opening up new possibilities for\nstudying complex structural processes, which can not be described with\ntraditional approaches.",
        "positive": "Brillouin light scattering study of Co$_{2}$Cr$_{0.6}$Fe$_{0.4}$Al and\n  Co$_{2}$FeAl Heusler compounds: The thermal magnonic spectra of Co$_{2}$Cr$_{0.6}$Fe$_{0.4}$Al (CCFA) and\nCo$_2$FeAl were investigated using Brillouin light scattering spectroscopy\n(BLS). For CCFA, the exchange constant A (exchange stiffness D) is found to be\n0.48 $\\mu$erg/cm (203 meV A$^2$), while for Co$_2$FeAl the corresponding values\nof 1.55 $\\mu$erg/cm (370 meV A$^2$) were found. The observed asymmetry in the\nBLS spectra between the Stokes and anti-Stokes frequencies was assigned to an\ninterplay between the asymmetrical profiles of hybridized Damon-Esbach and\nperpendicular standing spin-wave modes, combined with the optical sensitivity\nof the BLS signal to the upper side of the CCFA or Co$_2$FeAl film."
    },
    {
        "anchor": "First principles studies of the electronic and structural properties of\n  the rutile VO$_{2}$(110) surface and its oxygen-rich terminations: We present a Density Functional Theory (DFT) study of the structural and\nelectronic properties of bare rutile VO$_{2}$(110) surfaces and its oxygen-rich\nterminations. We discuss the performance of various DFT functionals, including\nPBE, PBE+U (U = 2 eV), SCAN and SCAN+rVV functionals with non-magnetic and\nferromagnetic spin ordering. We predict the presence of a ring-like termination\nthat is electronically and structurally related to a V$_{2}$O$_{5}$(001)\nmonolayer and shows a higher stability than pure oxygen adsorption phases.\nDespite the fact that the calculated phase stabilities depend on the chosen\nfunctional, our results show that employing the spin-polarized SCAN functional\noffers a good compromise yielding both a reasonable description of the\nstructural and electronic properties of the rutile VO$_{2}$ bulk phase and the\nenthalpy of formation for different stages of vanadium oxidation.",
        "positive": "Hollow carbon sphere/metal oxide nanocomposite anodes for lithium-ion\n  batteries: Hollow carbon spheres (HCS) covered with metal oxide nanoparticles (SnO2 and\nMnO2, respectively) were successfully synthesized and investigated regarding\ntheir potential as anode materials for lithium-ion batteries. Raman\nspectroscopy shows a high degree of graphitization for the HCS host structure.\nThe mesoporous nature of the nanocomposites is confirmed by\nBrunauer-Emmett-Teller analysis. For both metal oxides under study, the metal\noxide functionalization of HCS yields a significant increase of electrochemical\nperformance. The charge capacity of HCS/SnO2 is 370 mAh/g after 45 cycles (266\nmAh/g in HCS/MnO2) which clearly exceeds the value of 188 mAh/g in pristine\nHCS. Remarkably, the data imply excellent long term cycling stability after 100\ncycles in both cases. The results hence show that mesoporous HCS/metal oxide\nnanocomposites enable exploiting the potential of metal oxide anode materials\nin Lithium-ion batteries by providing a HCS host structure which is both\nconductive and stable enough to accommodate big volume change effects."
    },
    {
        "anchor": "Polarization superposition of room-temperature polariton condensation: A methodology for forming a qubit state is essential for quantum applications\nof room temperature polaritons. While polarization degree of freedom is\nexpected as a possible means for this purpose, the coupling of linearly\npolarized polariton condensed states has been still a challenging issue. In\nthis study, we show a polarization superposition of a polariton condensed\nstates in an all-inorganic perovskite microcavity at room temperature. We\nrealized the energy resonance of the two orthogonally polarized polariton modes\nwith the same number of antinodes by exploiting the blue shift of the polariton\ncondensed state. The polarization coupling between the condensed states results\nin a polarization switching in the polariton lasing emission. The orthorhombic\ncrystal structure of the perovskite active layer and/or a slight off-axis\norientation of the perovskite crystal axis from the normal direction of\nmicrocavity plane enable the interaction between the two orthogonally polarized\nstates. These observations demonstrate a great promise of polariton as a room\ntemperature qubit technology.",
        "positive": "Electronic structures of ternary iron arsenides AFe$_2$As$_2$ (A=Ba, Ca,\n  or Sr): We have studied the electronic and magnetic structures of the ternary iron\narsenides AFe$_2$As$_2$ (A = Ba, Ca, or Sr) using the first-principles density\nfunctional theory. The ground states of these compounds are in a collinear\nantiferromagnetic order, resulting from the interplay between the nearest and\nthe next-nearest neighbor superexchange antiferromagnetic interactions bridged\nby As $4p$ orbitals. The correction from the spin-orbit interaction to the band\nstructure is small. The pressure can reduce dramatically the magnetic moment\nand diminish the collinear antiferromagnetic order. Based on the calculations,\nwe propose that the low energy dynamics of these materials is described\neffectively by a $t-J_H-J_1-J_2$-type model."
    },
    {
        "anchor": "Localized spin-orbit polaron in magnetic Weyl semimetal\n  Co$_3$Sn$_2$S$_2$: The kagome lattice Co$_3$Sn$_2$S$_2$ exhibits the quintessential topological\nphenomena of a magnetic Weyl semimetal such as the chiral anomaly and Fermi-arc\nsurface states. Probing its magnetic properties is crucial for understanding\nthis correlated topological state. Here, using spin-polarized scanning\ntunneling microscopy/spectroscopy (STM/S), we report the discovery of localized\nspin-orbit polarons (SOPs) with three-fold rotation symmetry nucleated around\nsingle-S vacancies in Co$_3$Sn$_2$S$_2$. The SOPs carry a spin-polarized\nmagnetic moment and a large orbital magnetization of a topological origin\nassociated with the Berry phase and the persistent circulating current.\nAppreciable magneto-elastic coupling of the SOP is detected by atomic force\nmicroscope and STM. Our findings suggest that the SOPs can enhance magnetism\nand stability of the magnetic Weyl nodes for more robust\ntime-reversal-symmetry-breaking topological phenomena. Controlled engineering\nof the SOPs may pave the way toward practical applications in functional\nquantum devices.",
        "positive": "Ultra-hard rhombohedral carbon from crystal chemistry rationale and\n  first principles: A new ultra-hard rhombohedral carbon rh-C4 (or hexagonal h-C12) is reported\nas derived from 3R graphite through crystal chemistry construction and ground\nstate energy within the density functional theory. An extended hexagonal\nthree-dimensional network of h-C12 is formed of C4 tetrahedra alike in h-C4\nlonsdaleite (hexagonal diamond). The electronic band structure of rh-C4 is\ncharacteristic of insulator with Egap = 4 eV similarly to diamond. From the set\nof elastic constants a larger value of bulk modulus versus lonsdaleite, and the\nlargest Vickers hardness (HV) versus both forms of diamond were derived."
    },
    {
        "anchor": "Fracture of the $C$15 CaAl$_2$ Laves phase at small length-scales: The cubic $C$15 CaAl$_2$ Laves phase is a crucial brittle intermetallic\nprecipitate in Mg-Al-Ca alloys. Although knowledge of the mechanical properties\nof coexisting phases is essential for improved alloy design, the fracture\ntoughness is not yet studied experimentally due to the need for miniaturised\ntesting. Here, micropillar splitting and microcantilever bending are used to\nexperimentally determine the toughness of CaAl$_2$. It is found that the\ntoughness value of ~1 $MPa\\cdot\\sqrt m$ from pillar splitting is largely\ninsensitive to sample heat treatment, ion beam used for fabrication,\nmicropillar diameter, and surface orientation. From nanoindentation supported\nby electron channelling contrast imaging and backscatter diffraction, fracture\nis observed to take place mostly on {011} planes. Atomistic fracture\nsimulations on a model $C$15 Laves phase showed that the preference of {011}\ncleavage planes over the more energetically favourable {111} is due to lattice\ntrapping and kinetics controlling fracture. Using rectangular microcantilever\nbending tests where the notch plane was misoriented to the closest possible\n{112} cleavage plane by ~8{\\deg}, and the closest {001}, {011} and {111} plane\nby >20{\\deg}, a toughness of ca. 2 $MPa\\cdot\\sqrt m$ was determined along with\nthe electron microscopy observation of significant deviations of the crack\npath, demonstrating that preferential crystallographic cleavage planes\ndetermine the toughness in this material. Further investigation using\npentagonal microcantilevers with precise alignment of the notch with the\ncleavage planes revealed similar fracture toughness values for different\nlow-index planes. The results presented here are the first detailed\nexperimental study of fracture toughness of the $C$15 CaAl$_2$ Laves phase, and\ncan be understood in terms of crack plane and crack front dependent fracture\ntoughness.",
        "positive": "Anomalies in the temperature evolution of the Dirac states in a\n  topological crystalline insulator SnTe: Discovery of topologically protected surface states, believed to be immune to\nweak disorder and thermal effects, opened up a new avenue to reveal exotic\nfundamental science and advanced technology. While time-reversal symmetry plays\nthe key role in most such materials, the bulk crystalline symmetries such as\nmirror symmetry preserve the topological properties of topological crystalline\ninsulators (TCIs). It is apparent that any structural change may alter the\ntopological properties of TCIs. To investigate this relatively unexplored\nlandscape, we study the temperature evolution of the Dirac fermion states in an\narchetypical mirror-symmetry protected TCI, SnTe employing high-resolution\nangle-resolved photoemission spectroscopy and density functional theory\nstudies. Experimental results reveal a perplexing scenario; the bulk bands\nobserved at 22 K move nearer to the Fermi level at 60 K and again shift back to\nhigher binding energies at 120 K. The slope of the surface Dirac bands at 22 K\nbecomes smaller at 60 K and changes back to a larger value at 120 K. Our\nresults from the first-principles calculations suggest that these anomalies can\nbe attributed to the evolution of the hybridization physics with complex\nstructural changes induced by temperature. In addition, we discover drastically\nreduced intensity of the Dirac states at the Fermi level at high temperatures\nmay be due to complex evolution of anharmonicity, strain, etc. These results\naddress robustness of the topologically protected surface states due to thermal\neffects and emphasize importance of covalency and anharmonicity in the\ntopological properties of such emerging quantum materials."
    },
    {
        "anchor": "Study of ion beam induced mixing in nano-layered Si/C multilayer\n  structures: The effects of ion beam induced atomic mixing and subsequent thermal\ntreatment in Si/C multilayer structures are investigated by use of the\ntechnique of grazing incidence X-ray diffraction (GIXRD) and Raman\nspectroscopy. The [Si (3.0 nm) / C (2.5 nm)]x10 /Si multilayer films were\nprepared by electron beam evaporation under ultra high vacuum (UHV)\nenvironment. The layer thicknesses were measured using in-situ quartz crystal\noscillator. These multilayer films were subjected to 40 keV Ar+ ion irradiation\nwith fluences 5E-16 (low fluence) and 1E-17 ions / cm2 (high fluence).The\nas-prepared and irradiated multilayer samples were annealed at 773 K for one\nhour. The GIXRD and Raman spectroscopy results reveal the formation of\ndifferent phases of SiC in these multilayer structures. Deposition induced\nreactions at the nano-structured interface and subsequent room temperature Ar\nion irradiation at low fluence result in formation of the hexagonal SiC phase.\nHigh fluence Ar+ ion irradiation and subsequent annealing at 773 K for one hour\nleads to precipitation of the cubic-SiC phase.",
        "positive": "Simulation of ion-implanted boron redistribution under different\n  conditions of the transient enhanced diffusion suppression: It has been shown by means of impurity diffusion simulation that\nion-implanted boron redistribution at the annealing temperatures 800^{\\circ}C\nand lower is governed by the long-range migration of nonequilibrium impurity\ninterstitials regardless of the methods used for the transient enhanced\ndiffusion suppression. The relative amounts of impurity atoms, which are being\ntransferred to the transient interstitial position, have been determined and\ntime-average migration lengths of nonequilibrium boron interstitials have been\nobtained."
    },
    {
        "anchor": "Tracing the thermal mechanism in femtosecond spin dynamics: We compare femtosecond pump-probe experiments in Ni and micromagnetic\nmodelling based on the Landau-Lifshitz-Bloch equation coupled to a\ntwo-temperature model, revealing a predominant thermal ultrafast\ndemagnetization mechanism. We show that both spin (femtosecond demagnetization)\nand electron-phonon (magnetization recovery) rates in Ni increase as a function\nof the laser pump fluence. The slowing down for high fluences arises from the\nincreased longitudinal relaxation time.",
        "positive": "Nanoscale Structural and Electronic Properties of Cellulose/Graphene\n  Interfaces: The development of electronic devices based on the functionalization of\n(nano)cellulose platforms relies upon an atomistic understanding of the\nstructural, and electronic properties of the combined system,\ncellulose/functional element. In this work, we present a theoretical study of\nthe nanocellulose/graphene interface (nCL/G) based on first-principles\ncalculations. We find that the binding energies of both hydrophobic/G\n(nCL$^{\\rm phob}$/G) and hydrophilic/G (nCL$^{\\rm phil}$/G) interfaces are\nprimarily dictated by the van der Waals interactions, and are comparable with\nthat of their 2D interface counterparts. We verify that the energetic\npreference of nCL$^{\\rm phob}$/G has been reinforced by the inclusion of an\naqueous media via the implicit solvation model. Further structural\ncharacterization was carried out using a set of simulations of Carbon K-edge\nX-ray absorption spectra to identify and distinguish the key absorption\nfeatures of the nCL$^{\\rm phob}$/G and nCL$^{\\rm phil}$/G interfaces. The\nelectronic structure calculations reveal that the linear energy bands of\ngraphene lie in the band gap of the nCL, sheet, while depletion/accumulation\ncharge density regions are observed. We show that external agents, i.e.\nelectric field and mechanical strain, allow for tunability of the Dirac cone\nand the charge density at the interface. The control/maintenance of the Dirac\ncone states in nCL/G is an important feature for the development of electronic\ndevices based on cellulosic platforms."
    },
    {
        "anchor": "Dzyaloshinskii-Moriya interaction and Hall effects in the skyrmion phase\n  of MnFeGe alloys: We carry out density functional theory calculations which demonstrate that\nthe electron dynamics in the skyrmion phase of Fe-rich Mn$_{1-x}$Fe$_x$Ge\nalloys is governed by Berry phase physics. We observe that the magnitude of the\nDzyaloshinskii-Moriya interaction, directly related to the mixed space-momentum\nBerry phases, changes sign and magnitude with concentration $x$ in direct\ncorrelation with the data of Shibata {\\it et al.}, Nature Nanotech. {\\bf 8},\n723 (2013). The computed anomalous and topological Hall effects in FeGe are\nalso in good agreement with available experiments. We further develop a simple\ntight-binding model able to explain these findings. Finally, we show that the\nadiabatic Berry phase picture is violated in the Mn-rich limit of the alloys.",
        "positive": "Magnetic properties of cobalt ultrathin film structures controlled by\n  buffer layer roughness: Growth optimization of multilayers is a topic of interest due to their unique\nphysical properties. Systems containing magnetic materials, such as\nplatinum-cobalt, have been studied because of their potential for technological\napplications, e.g. spintronics, magnetic storage and magnetic sensors. Since\nthe magnetic properties of thin layers are strongly related to the growth\nparameters, the fine tuning of these parameters is necessary to produce\nmultilayers with specific properties required in various applications. Here, an\nefficient approach to tune the coercive field of Co ultrathin films in the\nmultilayer by varying the underlayer thickness is demonstrated. Using magnetron\nsputtering, we prepared multilayer systems of Au(x)/Pt(5nm)/Co(0.7nm)/Au(5nm)\nwith various thicknesses of Au underlayer. The surface morphology of\nAu(x)/Pt(5nm) stack on which Co layer was deposited was studied by atomic force\nmicroscopy. We show the possibility to control the interfacial roughness by\nchanging the Au underlayer thickness due to its island-like growth mechanism\n(Volmer-Weber mode). As the nominal thickness of Au increases, the islands grow\nin larger lateral size, resulting in a higher overall roughness of the layer\nsurface. Magnetization measurements indicate a direct influence of the\nunderlayer roughness on the coercivity of the multilayers by promoting\nadditional magnetic anisotropy. With thickness of the Au layer up to 20 nm, we\ncan change the coercive field in the range from ~200 Oe to ~1100 Oe, while\nremaining a nearly constant saturation magnetization. The use of Cu replacing\nAu underlayer in the same multilayers was also investigated, demonstrating the\npossibility of coercivity adjustment using different materials. The results are\nimportant for applications where the magnetic properties of multilayer\nstructures based on Co thin films could be adjusted via buffer layer roughness\nengineering."
    },
    {
        "anchor": "Dynamic Hardness Evolution in Metals from Impact Induced Gradient\n  Dislocation Density: A clear understanding of the dynamic behavior of metals is critical for\ndeveloping superior structural materials as well as for improving material\nprocessing techniques such as cold spray and shot peening. Using a high\nvelocity (from 120 m/s to 700 m/s; strain rates >10^7 1/s) micro-projectile\nimpact testing and quasistatic (strain rates: 10^-2 1/s) nanoindentation, we\ninvestigate the strain-rate-dependent mechanical behavior of single-crystal\naluminum substrates with (001), (011), and (111) crystal orientations. For all\nthree crystal orientations, the dynamic hardness initially increases with\nincreasing impact velocity and reaches a plateau regime at hardness 5 times\nhigher than that of at quasistatic indentations. Based on coefficient of\nrestitution and post mortem transmission Kikuchi diffraction analyses, we show\nthat distinct plastic deformation mechanisms with a gradient dislocation\ndensity evolution govern the dynamic behavior. We also discover a distinct\ndeformation regime-stable plastic regime-that emerge beyond the deeply plastic\nregime with unique strain rate insensitive microstructure evolution and dynamic\nhardness. Our work additionally demonstrates an effective approach to introduce\nstrong spatial gradient in dislocation density in metals by high-velocity\nprojectile impacts to enhance surface mechanical properties, as it can be\nemployed in material processing techniques such as shot peening and surface\nmechanical attrition treatment.",
        "positive": "Modeling of internal mechanical failure of all-solid-state batteries\n  during electrochemical cycling, and implications for battery design: This is the first quantitative analysis of mechanical reliability of\nall-solid state batteries. Mechanical degradation of the solid electrolyte (SE)\nis caused by intercalation-induced expansion of the electrode particles, within\nthe constrain of a dense microstructure. A coupled electro-chemo-mechanical\nmodel was implemented to quantify the material properties that cause a SE to\nfracture. The treatment of microstructural details is essential to the\nunderstanding of stress-localization phenomena and fracture. A cohesive zone\nmodel is employed to simulate the evolution of damage. In the numerical tests,\nfracture is prevented only if electrode-particle's expansion is lower than 7.5%\nand the solid-electrolyte's fracture energy higher than $G_c = 4$ J m$^{-2}$.\nPerhaps counter-intuitively, the analyses show that compliant solid\nelectrolytes (with Young's modulus in the order of E$_{SE} = 15$ GPa) are more\nprone to micro-cracking. This result, captured by our non-linear kinematics\nmodel, contradicts the speculations that sulfide SEs are more suitable for the\ndesign of bulk-type batteries than oxide SEs. Mechanical degradation is linked\nto the battery power-density. Fracture in solid Li-ion conductors represents a\nbarrier for Li transport, and accelerates the decay of rate performance."
    },
    {
        "anchor": "Isotope quantum effects in the metallization transition in liquid\n  hydrogen: Quantum effects in condensed matter normally only occur at low temperatures.\nHere we show a large quantum effect in high-pressure liquid hydrogen at\nthousands of Kelvins. We show that the metallization transition in hydrogen is\nsubject to a very large isotope effect, occurring hundreds of degrees lower\nthan the equivalent transition in deuterium. We examined this using path\nintegral molecular dynamics simulations which identify a liquid-liquid\ntransition involving atomization, metallization, and changes in viscosity,\nspecific heat and compressibility. The difference between H$_2$ and D$_2$ is a\nquantum mechanical effect which can be associated with the larger zero-point\nenergy in H$_2$ weakening the covalent bond. Our results mean that experimental\nresults on deuterium must be corrected before they are relevant to\nunderstanding hydrogen at planetary conditions.",
        "positive": "Molecular Dynamics Study of Self-Diffusion in Zr: We employed a recently developed semi-empirical Zr potential to determine the\ndiffusivities in the hcp and bcc Zr via molecular dynamics simulation. The\npoint defect concentration was determined directly from MD simulation rather\nthan from theoretical methods using T=0 calculations. We found that the\ndiffusion proceeds via the interstitial mechanism in the hcp Zr and both the\nvacancy and interstitial mechanisms give contribution in diffusivity in the bcc\nZr. The agreement with the experimental data is excellent for the hcp Zr and\nfor the bcc Zr it is rather good at high temperatures but there is a\nconsiderable disagreement at low temperatures."
    },
    {
        "anchor": "Broadband pump-probe study of biexcitons in chemically exfoliated\n  layered WS$_{2}$: Strong light-matter interactions in layered transition metal dichalcogenides\n(TMDs) open up vivid possibilities for novel exciton-based devices. The optical\nproperties of TMDs are dominated mostly by the tightly bound excitons and more\ncomplex quasiparticles, the biexcitons. Instead of physically exfoliated\nmonolayers, the solvent-mediated chemical exfoliation of these 2D crystals is a\ncost-effective, large-scale production method suitable for real device\napplications. We explore the ultrafast excitonic processes in WS$_{2}$\ndispersion using broadband femtosecond pump-probe spectroscopy at room\ntemperature. We detect the biexcitons experimentally and calculate their\nbinding energies, in excellent agreement with earlier theoretical predictions.\nUsing many-body physics, we show that the excitons act like Weiner-Mott\nexcitons and explain the origin of excitons via first-principles calculations.\nOur detailed time-resolved investigation provides ultrafast radiative and\nnon-radiative lifetimes of excitons and biexcitons in WS$_{2}$. Indeed, our\nresults demonstrate the potential for excitonic quasiparticle-controlled\nTMDs-based devices operating at room temperature.",
        "positive": "Site preference of transition-metal elements in L10-TiAl: A\n  first-principles study: The site preference of 3d (Ti-Cu), 4d (Zr-Ag) and 5d (Hf-Au) transition-metal\nelements in L10 TiAl is studied using a combination of first-principles\nsupercell calculations and the statistical mechanical Wagner-Schottky model.\nOur key finding is that both temperature and alloy stoichiometry can strongly\naffect the site occupancy behavior of ternary alloying elements in L10 TiAl. We\nfurther predict that the tendency of transition metals to occupy the Al sites\nin TiAl increases with increasing d-electron number along a series."
    },
    {
        "anchor": "Implanted Bottom Gate for Epitaxial Graphene on Silicon Carbide: We present a technique to tune the charge density of epitaxial graphene via\nan electrostatic gate that is buried in the silicon carbide substrate. The\nresult is a device in which graphene remains accessible for further\nmanipulation or investigation. Via nitrogen or phosphor implantation into a\nsilicon carbide wafer and subsequent graphene growth, devices can routinely be\nfabricated using standard semiconductor technology. We have optimized samples\nfor room temperature as well as for cryogenic temperature operation. Depending\non implantation dose and temperature we operate in two gating regimes. In the\nfirst, the gating mechanism is similar to a MOSFET, the second is based on a\ntuned space charge region of the silicon carbide semiconductor. We present a\ndetailed model that describes the two gating regimes and the transition in\nbetween.",
        "positive": "Sharp enhancement on thermoelectric figure-of-merit of post-transition\n  metal chalcogenides (PTMCs) using heterostructures with Mexican-hat valence\n  band: Post-transition metal chalcogenides (PTMCs) such as GaSe, GaS, InSe, and InS\nhave been proposed as promising thermoelectric materials due to low lattice\nconductivity, originating from the atomically layered structure, high Seebeck\ncoefficient, and the anticipation that its figure-of-merit be improved when\nthinned to few-layers as the band structure turns into Mexican-hat valence band\n(MHVB). Here we show by ab initio calculations that the MHVB should be present\neven on thick films of InSe/GaSe type-II heterostructures, and a 50%\nenhancement on thermoelectric figure-of-merit zT at room-temperature is\nexpected when compared with bulk InSe."
    },
    {
        "anchor": "Learning dislocation dynamics mobility laws from large-scale MD\n  simulations: The computational method of discrete dislocation dynamics (DDD), used as a\ncoarse-grained model of true atomistic dynamics of lattice dislocations, has\nbecome of powerful tool to study metal plasticity arising from the collective\nbehavior of dislocations. As a mesoscale approach, motion of dislocations in\nthe DDD model is prescribed via the mobility law; a function which specifies\nhow dislocation lines should respond to the driving force. However, the\ndevelopment of traditional hand-crafted mobility laws can be a cumbersome task\nand may involve detrimental simplifications. Here we introduce a\nmachine-learning (ML) framework to streamline the development of data-driven\nmobility laws which are modeled as graph neural networks (GNN) trained on\nlarge-scale Molecular Dynamics (MD) simulations of crystal plasticity. We\nillustrate our approach on BCC tungsten and demonstrate that our GNN mobility\nimplemented in large-scale DDD simulations accurately reproduces the\nchallenging tension/compression asymmetry observed in ground-truth MD\nsimulations while correctly predicting the flow stress at lower straining rate\nconditions unseen during training, thereby demonstrating the ability of our\nmethod to learn relevant dislocation physics. Our DDD+ML approach opens new\npromising avenues to improve fidelity of the DDD model and to incorporate more\ncomplex dislocation motion behaviors in an automated way, providing a faithful\nproxy for dislocation dynamics several orders of magnitude faster than\nground-truth MD simulations.",
        "positive": "Ultrafast dynamics of electrons excited by femtosecond laser pulses:\n  spin polarization and spin-polarized currents: Laser radiation incident on a ferromagnetic sample produces excited electrons\nand currents whose spin polarization must not be aligned with the magnetization\n-- an effect due to spin-orbit coupling that is ubiquitous in spin- and\nangle-resolved photoemission. In this Paper, we report on a systematic\ninvestigation of the dynamics of spin polarization and spin-polarized currents\nproduced by femtosecond laser pulses, modeled within our theoretical framework\nEVOLVE. The spin polarization depends strongly on the properties of the laser\npulse and on the sample composition, as is shown by comparing results for\nCu(100), Co(100), and a Co/Cu heterostructure. We find a transition from\ncoherence before the laser pulse's maximum to incoherence thereafter. Moreover,\nthe time dependence of the spin-polarization components induced by spin-orbit\ncoupling differ significantly in Cu and Co: in Cu, we find long-period\noscillations with tiny rapid modulations, whereas in Co prominent rapid\noscillations with long period ones are superimposed. The pronounced spatial\ndependencies of the signals underline the importance of inhomogeneities, in\nparticular magnetic/non-magnetic interfaces `act as source' for ultrafast\nspin-polarization effects. Our investigation provides detailed insight into\nelectron dynamics during and shortly after a femtosecond laser excitation."
    },
    {
        "anchor": "Spatial Mapping of Electrostatics and Dynamics across 2D\n  Heterostructures: In situ electron microscopy is a key tool for understanding the mechanisms\ndriving novel phenomena in 2D structures. Unfortunately, due to various\npractical challenges, technologically relevant 2D heterostructures prove\nchallenging to address with electron microscopy. Here, we use the differential\nphase contrast imaging technique to build a methodology for probing local\nelectrostatic fields during electrical operation with nanoscale precision in\nsuch materials. We find that by combining a traditional DPC setup with a high\npass filter, we can largely eliminate electric fluctuations emanating from\nshort-range atomic potentials. With this method, a priori electric field\nexpectations can be directly compared with experimentally derived values to\nreadily identify inhomogeneities and potentially problematic regions. We use\nthis platform to analyze the electric field and charge density distribution\nacross layers of hBN and MoS2.",
        "positive": "Formation and decay of electron-hole droplets in diamond: We study the formation and decay of electron-hole droplets in diamonds at\nboth low and high temperatures under different excitations by master equations.\nThe calculation reveals that at low temperature the kinetics of the system\nbehaves as in direct-gap semiconductors, whereas at high temperature it shows\nmetastability as in traditional indirect-gap semiconductors. Our results at low\ntemperature are consistent with the experimental findings by Nagai {\\em et al.}\n[Phys. Rev. B {\\bf 68}, 081202 (R) (2003)]. The kinetics of the e-h system in\ndiamonds at high temperature under both low and high excitations is also\npredicted."
    },
    {
        "anchor": "From wetting to melting along grain boundaries using phase field and\n  sharp interface methods: We investigate the ability of a multi-order parameter phase field model with\nobstacle potentials to describe grain boundary premelting in equilibrium\nsituations. In agreement with an energetic picture we find that the transition\nbetween dry and wet grain boundaries at the bulk melting point is given by the\nthreshold $2\\sigma_{sl}=\\sigma_{gb}$, with $\\sigma_{sl}$ being the solid-melt\ninterfacial energy and $\\sigma_{gb}$ the energy of a dry grain boundary. The\npredictions for premelting are confirmed by simulations using the phase field\npackage OpenPhase. For the prediction of the kinetics of melting along grain\nboundaries in pure materials, taking into account the short ranged interactions\nwhich are responsible for the grain boundary premelting, a sharp interface\ntheory is developed. It confirms that for overheated grain boundaries the\nmelting velocity is reduced (increased) for non-wetting (wetting) grain\nboundaries. Numerical steady state predictions are in agreement with a fully\nanalytical solution in a subset of the parameter space. Phase field simulations\nconfirm the predictions of the sharp interface theory.",
        "positive": "Investigation on the Physical Properties of Two Laves Phase Compounds\n  HRh2 (H = Ca and La): A DFT Study: Structural, elastic, electronic and optical properties of laves phase\nintermetallic compounds CaRh2 and LaRh2 prototype with MgCu2 are investigated\nby using the first principle calculations. These calculations stand on density\nfunctional theory (DFT) from CASTEP code. The calculated lattice parameters are\nconsistent with the experimental values. The significant elastic properties,\nlike as bulk modulus, shear modulus, Youngs modulus and the Poissons ratio are\ndetermined by applying the Voigt Reuss Hill (VRH) approximation. The analysis\nof Pughs ratio shows the ductile nature of both the phases. Metallic\nconductivity is observed for both the compounds. Most of the contribution\noriginates from Rh 4d states at Fermi level in DOS. The study of bonding\ncharacteristics reveals the existence of ionic and metallic bonds in both\nintermetallics. The study of optical properties indicates that maximum\nreflectivity occurs in low energy region implying the characteristics of high\nconductance of both the phases. Absorption quality of both the phases is good\nin the visible region."
    },
    {
        "anchor": "Pt-induced nanowires on Ge(001): a DFT study: We study formation of the nanowires formed after deposition of Pt on a\nGe(001) surface. The nanowires form spontaneously after high temperature\nannealing. They are thermodynamically stable, only one atom wide and up to a\nfew hundred atoms long. Ab initio density functional theory calculations are\nperformed to identify possible structures of the Pt-Ge (001) surface with\nnanowires on top. A large number of structures is studied. With nanowires that\nare formed out of Pt or Ge dimers or mixed Pt-Ge dimers. By comparing simulated\nscanning tunneling microscopy images with experimental ones we model the\nformation of the nanowires and identify the geometries of the different phases\nin the formation process. We find that the formation of nanowires on a\nPt-Ge(001) surface is a complex process based on increasing the Pt density in\nthe top layers of the Ge(001) surface. Most remarkably we find the nanowires to\nconsist of germanium dimers placed in troughs lined by mixed Pt-Ge dimer rows.",
        "positive": "All-wurtzite (In,Ga)As-(Ga,Mn)As core-shell nanowires grown by molecular\n  beam epitaxy: Structural and magnetic properties of (In,Ga)As-(Ga,Mn)As core-shell\nnanowires grown by molecular beam epitaxy on GaAs(111)B substrate with gold\ncatalyst have been investigated.(In,Ga)As core nanowires were grown at high\ntemperature (500 {\\deg}C) whereas (Ga,Mn)As shells were deposited on the\n{1-100} side facets of the cores at much lower temperature (220 {\\deg}C). High\nresolution transmission electron microscopy images and high spectral resolution\nRaman scattering data show that both the cores and the shells of the nanowires\nhave wurtzite crystalline structure. Scanning and transmission electron\nmicroscopy observations show smooth (Ga,Mn)As shells containing 5% of Mn\nepitaxially deposited on (In,Ga)As cores containing about 10% of In, without\nany misfit dislocations at the core-shell interface. With the In content in the\n(In,Ga)As cores larger than 5% the (In,Ga)As lattice parameter is higher than\nthat of (Ga,Mn)As and the shell is in the tensile strain state. Elaborated\nmagnetic studies indicate the presence of ferromagnetic coupling in (Ga,Mn)As\nshells at the temperatures in excess of 33 K. This coupling is maintained only\nin separated mesoscopic volumes resulting in an overall superparamagnetic\nbehavior which gets blocked below ~17 K."
    },
    {
        "anchor": "Phononic band structure of honeycomb lattice with defects, using\n  spectrally formulated finite element method: A spectrally formulated finite element analysis based methodology has been\nproposed to calculate phononic band structure of reticulated honeycomb lattices\nhaving translationally invariant repetitive elements called unit cells. Bloch\nformulation captures dynamics of infinite structure through that of a unit\ncell. While conventional FEM is generally used for analyzing dynamics of such\nunit systems, here, constituent structural members are treated as 1D waveguide\nand modeled as Timoshenko beam frame element, enabling application of spectral\nFEM, suitable for accurately analyzing the dynamics, particularly efficient at\nvery high frequencies. Using exact solutions as shape functions spares dense\nmeshing. Resulting eigenvalue problem is solved by Wittrick-Williams method, an\niterative scheme. Subsequently, band structures are obtained for supercells-\nunits comprising multiple elemental unit cells; compared and reconciled with\nthose obtained using elemental cell (termed primitive unit cell to distinguish\nfrom supercell). Primitive cell band structures are reconstructed from\nSupercell band structures. Supercell band structures show some spurious bands,\nwhich are explained in terms of band folding in the primitive cell band\nstructure. Supercell allows treatment of defects as a periodic feature with\ncertain defect density. Of particular observation in such band structures is\nthe separation of bands, known as degeneracy breaking.",
        "positive": "Static Friction between Elastic Solids due to Random Asperities: Several workers have established that the Larkin domains for two three\ndimensional nonmetallic elastic solids in contact with each other at a\ndisordered interface are enormously large. This implies that there should be\nnegligible static friction per unit area in the macroscopic solid limit.\n  The present work argues that the fluctuations in the heights of the random\nasperities at the interface that occur in the Greenwood-Williamson model can\naccount for static friction."
    },
    {
        "anchor": "Estimation of residual carrier density near the Dirac point in graphene\n  through quantum capacitance measurement: We discuss the residual carrier density (n*) near the Dirac point (DP) in\ngraphene estimated by quantum capacitance (CQ) and conductivity measurements.\nThe CQ at the DP has a finite value and is independent of the temperature. A\nsimilar behavior is also observed for the conductivity at the DP, because their\norigin is residual carriers induced externally by charged impurities. The n*\nextracted from CQ, however, is often smaller than that from the conductivity,\nsuggesting that the mobility in the puddle region is lower than that in the\nlinear region. The CQ measurement should be employed for estimating n*\nquantitatively.",
        "positive": "Cleaning graphene: comparing heat treatments in air and in vacuum: Surface impurities and contamination often seriously degrade the properties\nof two-dimensional materials such as graphene. To remove contamination, thermal\nannealing is commonly used. We present a comparative analysis of annealing\ntreatments in air and in vacuum, both ex situ and \"pre-situ\", where an\nultra-high vacuum treatment chamber is directly connected to an\naberration-corrected scanning transmission electron microscope. While ex situ\ntreatments do remove contamination, it is challenging to obtain atomically\nclean surfaces after ambient transfer. However, pre-situ cleaning with\nradiative or laser heating appears reliable and well suited to clean graphene\nwithout undue damage to its structure."
    },
    {
        "anchor": "Fe/V and Fe/Co (001) superlattices: growth, anisotropy, magnetisation\n  and magnetoresistance: Some physical properties of bcc Fe/V and Fe/Co (001) superlattices are\nreviewed. The dependence of the magnetic anisotropy on the in-plane strain\nintroduced by the lattice mismatch between Fe and V is measured and compared to\na theoretical derivation. The dependence of the magnetic anisotropy (and\nsaturation magnetisation) on the layer thickness ratio Fe/Co is measured and a\nvalue for the anisotropy of bcc Co is derived from extrapolation. The\ninterlayer exchange coupling of Fe/V superlattices is studied as a function of\nthe layer thickness V (constant Fe thickness) and layer thickness of Fe\n(constant V thickness). A region of antiferromagnetic coupling and GMR is found\nfor V thicknesses 12-14 monolayers. However, surprisingly, a 'cutoff' of the\nantiferromagnetic coupling and GMR is found when the iron layer thickness\nexceeds about 10 monolayers.",
        "positive": "Domain Structures in Confined Nanoferroelectrics: Phase Field Approach: Phase field modeling of domain structures in ferroelectrics nanorods of\ndifferent shape and sizes is presented. The vortex domain configurations in\nconfined ferroelectrics have been explored by varying the ratio of the energies\nof electrostatic and elastic interactions. It is shown that a strong effect of\nthe electrostatic interactions can cause the formation of 90o domain walls that\ndo not satisfy the condition of strain compatibility. A good agreement between\nthe results of phase field modeling and the results of atomistic calculations\nfor nano ferroelectrics demonstrates that the phase field approach provides an\neffective tool for the analysis of domain structures in nano-ferroelectrics."
    },
    {
        "anchor": "Low damping and microstructural perfection of sub-40nm-thin yttrium iron\n  garnet films grown by liquid phase epitaxy: The field of magnon spintronics is experiencing an increasing interest in the\ndevelopment of solutions for spin-wave-based data transport and processing\ntechnologies that are complementary or alternative to modern CMOS\narchitectures. Nanometer-thin yttrium iron garnet (YIG) films have been the\ngold standard for insulator-based spintronics to date, but a potential process\ntechnology that can deliver perfect, homogeneous large-diameter films is still\nlacking. We report that liquid phase epitaxy (LPE) enables the deposition of\nnanometer-thin YIG films with low ferromagnetic resonance losses and\nconsistently high magnetic quality down to a thickness of 20 nm. The obtained\nepitaxial films are characterized by an ideal stoichiometry and perfect film\nlattices, which show neither significant compositional strain nor geometric\nmosaicity, but sharp interfaces. Their magneto-static and dynamic behavior is\nsimilar to that of single crystalline bulk YIG. We found, that the Gilbert\ndamping coefficient alpha is independent of the film thickness and close to 1 x\n10-4, and that together with an inhomogeneous peak-to-peak linewidth broadening\nof delta H0|| = 0.4 G, these values are among the lowest ever reported for YIG\nfilms with a thickness smaller than 40 nm. These results suggest, that\nnanometer-thin LPE films can be used to fabricate nano- and micro-scaled\ncircuits with the required quality for magnonic devices. The LPE technique is\neasily scalable to YIG sample diameters of several inches.",
        "positive": "First-principles study of the relaxor ferroelectricity of Ba(Zr,Ti)O$_3$: Ba(Zr,Ti)O$_3$ is a lead-free relaxor ferroelectric. Using the\nfirst-principles method, the ferroelectric dipole moments for pure BaTiO$_3$\nand Ba(Zr,Ti)O$_3$ supercells have been studied. All possible ion\nconfigurations of BaZr$_{0.5}$Ti$_{0.5}$O$_3$ and BaZr$_{0.25}$Ti$_{0.75}$O$_3$\nare constructed in a $2\\times2\\times2$ supercell. For the half-substituted\ncase, divergence of ferroelectric properties has been found among these\nstructures, which seriously depends on the arrangement of Ti and Zr ions. Thus\nour results provide a reasonable explanation to the relaxor behavior of\nBa(Zr,Ti)O$_3$. In addition, a model based on the thermal statistics gives the\naveraged polarization for Ba(Zr,Ti)O$_3$, which depends on the temperature of\nsynthesis. Our result is helpful to understand and tune the relaxor\nferroelectricity of lead-free Ba(Zr,Ti)O$_3$."
    },
    {
        "anchor": "Current distribution in metallic multilayers from resistance\n  measurements: The in-plane current profile within multilayers of generic structure\nTa/Pt/(CoNi)/Pt/Ta is investigated. A large set of samples where the thickness\nof each layer is systematically varied was grown, followed by the measurement\nof the sheet resistance of each sample. The data are analyzed by a series of\nincreasingly elaborate models, from a macroscopic engineering approach to\nmesoscopic transport theory. Non-negligible variations of the estimated\nrepartition of current between the layers are found. The importance of having\nadditional structural data is highlighted.",
        "positive": "Dynamical Control of Interlayer Excitons and Trions in\n  WSe$_2$/Mo$_{0.5}$W$_{0.5}$Se$_2$ Heterobilayer via Tunable Near-Field Cavity: Emerging photo-induced excitonic processes in transition metal dichalcogenide\n(TMD) heterobilayers, e.g., coupling, dephasing, and energy transfer of intra-\nand inter-layer excitons, allow new opportunities for ultrathin photonic\ndevices. Yet, with the associated large degree of spatial heterogeneity,\nunderstanding and controlling their complex competing interactions at the\nnanoscale remains a challenge. Here, we present an all-round dynamic control of\nintra- and inter-layer excitonic processes in a\nWSe$_2$/Mo$_{0.5}$W$_{0.5}$Se$_2$ heterobilayer using multifunctional\ntip-enhanced photoluminescence (TEPL) spectroscopy. Specifically, we control\nthe radiative recombination path and emission rate, electronic bandgap energy,\nand neutral to charged exciton conversion with <20 nm spatial resolution in a\nreversible manner. It is achieved through the tip-induced engineering of Au\ntip-heterobilayer distance and interlayer distance, GPa scale local pressure,\nand plasmonic hot-electron injection respectively, with simultaneous\nspectroscopic TEPL measurements. This unique nano-opto-electro-mechanical\ncontrol approach provides new strategies for developing versatile\nnano-excitonic devices based on TMD heterobilayers."
    },
    {
        "anchor": "Suns-V$_\\textrm{OC}$ characteristics of high performance kesterite solar\n  cells: Low open circuit voltage ($V_{OC}$) has been recognized as the number one\nproblem in the current generation of Cu$_{2}$ZnSn(Se,S)$_{4}$ (CZTSSe) solar\ncells. We report high light intensity and low temperature Suns-$V_{OC}$\nmeasurement in high performance CZTSSe devices. The Suns-$V_{OC}$ curves\nexhibit bending at high light intensity, which points to several prospective\n$V_{OC}$ limiting mechanisms that could impact the $V_{OC}$, even at 1 sun for\nlower performing samples. These V$_{OC}$ limiting mechanisms include low bulk\nconductivity (because of low hole density or low mobility), bulk or interface\ndefects including tail states, and a non-ohmic back contact for low carrier\ndensity CZTSSe. The non-ohmic back contact problem can be detected by\nSuns-$V_{OC}$ measurements with different monochromatic illumination. These\nlimiting factors may also contribute to an artificially lower $J_{SC}$-$V_{OC}$\ndiode ideality factor.",
        "positive": "Electronic structure of the molecule based magnet Cu PM(NO3)2 (H2O)2: We present density functional calculations on the molecule based S=1/2\nantiferromagnetic chain compound Cu PM(NO3)2 (H2O)2; PM = pyrimidine. The\nproperties of the ferro- and antiferromagnetic state are investigated at the\nlevel of the local density approximation and with the hybrid functional B3LYP.\nSpin density maps illustrate the exchange path via the pyrimidine molecule\nwhich mediates the magnetism in the one-dimensional chain. The computed\nexchange coupling is antiferromagnetic and in reasonable agreement with the\nexperiment. It is suggested that the antiferromagnetic coupling is due to the\npossibility of stronger delocalization of the charges on the nitrogen atoms,\ncompared to the ferromagnetic case. In addition, computed isotropic and\nanisotropic hyperfine interaction parameters are compared with recent NMR\nexperiments."
    },
    {
        "anchor": "Robust Diamond/\\b{eta}-Ga2O3 Hetero-p-n-junction Via Mechanically\n  Integrating Their Building Blocks: We report a novel approach for crafting robust diamond/\\b{eta}-Ga2O3\nhetero-p-n-junctions through the mechanical integration of their bulk\nmaterials. This resulting heterojunction, with a turn-on voltage of ~2.7 V at\nroom temperature, exhibits resilient electrical performance across a\ntemperature spectrum up to 125{\\deg}C, displaying minimal hysteresis-measuring\nas low as 0.2 V at room temperature and below 0.7 V at 125{\\deg}C. Remarkably,\nthe ideality factor achieves a record low value of 1.28, setting a new\nbenchmark for diamond/ \\b{eta}-Ga2O3 heterojunctions. The rectification ratio\nreaches over 10^8 at different temperatures. This effortlessly fabricated and\nremarkably resilient diamond/Ga2O3 hetero-p-n-junction pioneers a novel pathway\nfor the exploration and fabrication of heterojunctions for ultra-wide bandgap\nsemiconductors with substantial lattice mismatch and different thermal\nexpansion coefficients.",
        "positive": "Highly Fluorinated Graphene: We give the results of density functional calculations for graphene with a\nwidely varying fluorine adsorptions. We give a systematic analysis of the\nadsorption energies, lattice constants, bulk modulus, bandgap openings, and\nmagnetic properties. We find that a number of different adsorption geometries\nand a range of physical properties can occur for each adsorbate coverage. The\nsystems are found to range from metallic to semiconducting with widely vary\nband gaps, and a number of interesting magnetic phases are found. We expect\nthat many of these structures may occur in real materials systems. Further that\na listing of the properties found here may help in determining what fluorinated\ngraphenes are produced experimentally."
    },
    {
        "anchor": "Magnetoelectric effect arising from a field-induced pseudo Jahn-Teller\n  distortion in a rare earth magnet: Magnetoelectric materials are attractive for several applications, including\nactuators, switches, and magnetic field sensors. Typical mechanisms for\nachieving a strong magnetoelectric coupling are rooted in transition metal\nmagnetism. In sharp contrast, here we identify CsEr(MoO4)2 as a magnetoelectric\nmaterial without magnetic transition metal ions, thus ensuring that the Er ions\nplay a key role in achieving this interesting property. Our detailed study\nincludes measurements of the structural, magnetic, and electric properties of\nthis material. Bulk characterization and neutron powder diffraction show no\nevidence for structural phase transitions down to 0.3 K and therefore\nCsEr(MoO4)2 maintains the room temperature P2/c space group over a wide\ntemperature range without external magnetic field. These same measurements also\nidentify collinear antiferromagnetic ordering of the Er3+ moments below TN =\n0.87 K. Complementary dielectric constant and pyroelectric current measurements\nreveal that a ferroelectric phase (P ~ 0.5 nC/cm2) emerges when applying a\nmodest external magnetic field, which indicates that this material has a strong\nmagnetoelectric coupling. We argue that the magnetoelectric coupling in this\nsystem arises from a pseudo Jahn-Teller distortion induced by the magnetic\nfield.",
        "positive": "First-principles molecular dynamics simulations of proton diffusion in\n  cubic BaZrO3 perovskite under strain conditions: First-principles molecular dynamics simulations have been employed to analyze\nthe proton diffusion in cubic BaZrO3 perovskite at 1300K, and a non-linear\neffect of an applied isometric strain of 2% on the lattice parameter has been\nobserved. The structural and electronic properties of BaZrO3 are analyzed,\nbased on Density Functional Theory calculations, and after an analysis of the\nelectronic structure, we provide a possible explanation for an enhanced ionic\nconductivity, that can be caused by the formation of a preferential path for\nproton diffusion under compressive strain conditions."
    },
    {
        "anchor": "Microscopic evidence for a chiral superconducting order parameter in the\n  heavy fermion superconductor UTe2: Spin-triplet superconductivity is a condensate of electron pairs with spin-1\nand an odd-parity wavefunction. A particularly interesting manifestation of\ntriplet pairing is a chiral p-wave state which is topologically non-trivial and\na natural platform for realizing Majorana edge modes. Triplet pairing is\nhowever rare in solid state systems and so far, no unambiguous identification\nhas been made in any bulk compound. Since pairing is most naturally mediated by\nferromagnetic spin fluctuations, uranium based heavy fermion systems containing\nf electron elements that can harbor both strong correlations and magnetism are\nconsidered ideal candidate spin-triplet superconductors. In this work we\npresent scanning tunneling microscopy (STM) studies of the newly discovered\nheavy fermion superconductor, UTe2 with a T$_{SC}$ of 1.6 K. We find signatures\nof coexisting Kondo effect and superconductivity which show competing spatial\nmodulations within one unit-cell. STM spectroscopy at step edges show\nsignatures of chiral in-gap states, predicted to exist at the boundaries of a\ntopological superconductor. Combined with existing data indicating triplet\npairing, the presence of chiral edge states suggests that UTe2 is a strong\ncandidate material for chiral-triplet topological superconductivity.",
        "positive": "Magnetotransport properties of a polarization-doped three-dimensional\n  electron slab: We present evidence of strong Shubnikov-de-Haas magnetoresistance\noscillations in a polarization-doped degenerate three-dimensional electron slab\nin an Al$_{x}$Ga$_{1-x}$N semiconductor system. The degenerate free carriers\nare generated by a novel technique by grading a polar alloy semiconductor with\nspatially changing polarization. Analysis of the magnetotransport data enables\nus to extract an effective mass of $m^{\\star}=0.19 m_{0}$ and a quantum\nscattering time of $\\tau_{q}= 0.3 ps$. Analysis of scattering processes helps\nus extract an alloy scattering parameter for the Al$_{x}$Ga$_{1-x}$N material\nsystem to be $V_{0}=1.8eV$."
    },
    {
        "anchor": "Commensurability between element symmetry and the number of skyrmions\n  governing skyrmion diffusion in confined geometries: Magnetic skyrmions are topological magnetic structures, which exhibit\nquasi-particle properties and can show enhanced stability against perturbation\nfrom thermal noise. Recently, thermal Brownian diffusion of these\nquasi-particles has been found in continuous films and applications in\nunconventional computing have received significant attention, which however\nrequire structured elements. Thus, as the next necessary step, we here study\nskyrmion diffusion in confined geometries and find it to be qualitatively\ndifferent: The diffusion is governed by the interplay between the total number\nof skyrmions and the structure geometry. In particular, we ascertain the effect\nof circular and triangular geometrical confinement and find that for triangular\ngeometries the behavior is drastically different for the cases when the number\nof skyrmions in the element is either commensurate or incommensurate with a\nsymmetric filling of the element. This influence of commensurability is\ncorroborated by simulations of a quasi-particle model.",
        "positive": "Density functional simulation of small Fe nanoparticles: We calculate from first principles the electronic structure, relaxation and\nmagnetic moments in small Fe particles, applying the numerical local orbitals\nmethod in combination with norm-conserving pseudopotentials. The accuracy of\nthe method in describing elastic properties and magnetic phase diagrams is\ntested by comparing benchmark results for different phases of crystalline iron\nto those obtained by an all-electron method. Our calculations for the\nbipyramidal Fe_5 cluster qualitatively and quantitatively confirm previous\nplane-wave results that predicted a non-collinear magnetic structure. For\nlarger bcc-related (Fe_35) and fcc-related (Fe_38, Fe_43, Fe_62) particles, a\nlarger inward relaxation of outer shells has been found in all cases,\naccompanied by an increase of local magnetic moments on the surface to beyond 3\nmu_B."
    },
    {
        "anchor": "The Defects Genome of 2D Janus Transition Metal Dichalcogenides: Two-dimensional (2D) Janus Transition Metal Dichalcogenides (TMDs) have\nattracted much interest due to their exciting quantum properties arising from\ntheir unique two-faced structure, broken-mirror symmetry, and consequent\ncolossal polarisation field within the monolayer. While efforts have been made\nto achieve high-quality Janus monolayers, the existing methods rely on highly\nenergetic processes that introduce unwanted grain-boundary and point defects\nwith still unexplored effects on the material's structural and excitonic\nproperties Through High-resolution scanning transmission electron microscopy\n(HRSTEM), density functional theory (DFT), and optical spectroscopy\nmeasurements; this work introduces the most encountered and energetically\nstable point defects. It establishes their impact on the material's optical\nproperties. HRSTEM studies show that the most energetically stable point\ndefects are single (Vs and Vse) and double chalcogen vacancy (Vs-Vse),\ninterstitial defects (Mi), and metal impurities (MW) and establish their\nstructural characteristics. DFT further establishes their formation energies\nand related localized bands within the forbidden band. Cryogenic excitonic\nstudies on h-BN-encapsulated Janus monolayers offer a clear correlation between\nthese structural defects and observed emission features, which closely align\nwith the results of the theory. The overall results introduce the defect genome\nof Janus TMDs as an essential guideline for assessing their structural quality\nand device properties.",
        "positive": "Single nitrogen vacancy centers in chemical vapor deposited diamond\n  nanocrystals: Nanodiamond crystals containing single color centers have been grown by\nchemical vapor deposition (CVD). The fluorescence from individual crystallites\nwas directly correlated with crystallite size using a combined atomic force and\nscanning confocal fluorescence microscope. Under the conditions employed, the\noptimal size for single optically active nitrogen-vacancy (NV) center\nincorporation was measured to be 60 to 70 nm. The findings highlight a strong\ndependence of NV incorporation on crystal size, particularly with crystals less\nthan 50 nm in size."
    },
    {
        "anchor": "Developing Dipole-scheme Heterojunction Photocatalysts: The high recombination rate of photogenerated carriers is the bottleneck of\nphotocatalysis, severely limiting the photocatalytic efficiency. Here, we\ndevelop a dipole-scheme (D-scheme for short) photocatalytic model and materials\nrealization. The D-scheme heterojunction not only can effectively separate\nelectrons and holes by a large polarization field, but also boosts\nphotocatalytic redox reactions with large driving photovoltages and without any\ncarrier loss. By means of first-principles and GW calculations, we propose a\nD-scheme heterojunction prototype with two real polar materials, PtSeTe/LiGaS2.\nThis D-scheme photocatalyst exhibits a high capability of the photogenerated\ncarrier separation and near-infrared light absorption. Moreover, our\ncalculations of the Gibbs free energy imply a high ability of the hydrogen and\noxygen evolution reaction by a large driving force. The proposed D-scheme\nphotocatalytic model is generalized and paves a valuable route of significantly\nimproving the photocatalytic efficiency.",
        "positive": "Raman and Photoluminescence Study of Dielectric and Thermal Effects on\n  Atomically Thin MoS2: Atomically thin two-dimensional molybdenum disulfide (MoS2) sheets have\nattracted much attention due to their potential for future electronic\napplications. They not only present the best planar electrostatic control in a\ndevice, but also lend themselves readily for dielectric engineering. In this\nwork, we experimentally investigated the dielectric effect on the Raman and\nphotoluminescence (PL) spectra of monolayer MoS2 by comparing samples with and\nwithout HfO2 on top by atomic layer deposition (ALD). Based on considerations\nof the thermal, doping, strain and dielectric screening influences, it is found\nthat the red shift in the Raman spectrum largely stems from modulation doping\nof MoS2 by the ALD HfO2, and the red shift in the PL spectrum is most likely\ndue to strain imparted on MoS2 by HfO2. Our work also suggests that due to the\nintricate dependence of band structure of monolayer MoS2 on strain, one must be\ncautious to interpret its Raman and PL spectroscopy."
    },
    {
        "anchor": "Reflection and implantation of low energy helium with tungsten surfaces: Reflection and implantation of low energy helium (He) ions by tungsten (W)\nsubstrate are studied using molecular dynamics (MD) simulations. Motivated by\nthe ITER divertor design, our study considers a range of W substrate\ntemperatures (300 K, 1000 K, 1500 K), a range of He atom incidence energies\n($\\le$100 eV) and a range of angles of incidence ($0^{\\circ}$-$75^{\\circ}$)\nwith respect to substrate normal. The MD simulations quantify the reflection\nand implantation function, the integrated moments such as the particle/energy\nreflection coefficients and average implantation depths. Distributions of\nimplantation depths, reflected energy, polar and azimuthal angles of reflection\nare obtained, as functions of simulation parameters, such as W substrate\ntemperature, polar angle of incidence, the energy of incident He, and the type\nof W substrate surface. Comparison between the MD simulation results, the\nresults obtained using SRIM simulation package, and the existing experimental\nand theoretical results is provided.",
        "positive": "Global fixed point proof of time-dependent density-functional theory: We reformulate and generalize the uniqueness and existence proofs of\ntime-dependent density-functional theory. The central idea is to restate the\nfundamental one-to-one correspondence between densities and potentials as a\nglobal fixed point question for potentials on a given time-interval. We show\nthat the unique fixed point, i.e. the unique potential generating a given\ndensity, is reached as the limiting point of an iterative procedure. The\none-to-one correspondence between densities and potentials is a straightforward\nresult provided that the response function of the divergence of the internal\nforces is bounded. The existence, i.e. the v-representability of a density, can\nbe proven as well provided that the operator norms of the response functions of\nthe members of the iterative sequence of potentials have an upper bound. The\ndensities under consideration have second time-derivatives that are required to\nsatisfy a condition slightly weaker than being square-integrable. This approach\navoids the usual restrictions of Taylor-expandability in time of the uniqueness\ntheorem by Runge and Gross [Phys.Rev.Lett.52, 997 (1984)] and of the existence\ntheorem by van Leeuwen [Phys.Rev.Lett. 82, 3863 (1999)]. Owing to its\ngenerality, the proof not only answers basic questions in density-functional\ntheory but also has potential implications in other fields of physics."
    },
    {
        "anchor": "A Methodology for Thermal Simulation of Interconnects Enabled by Model\n  Reduction with Material Property Variation: A thermal simulation methodology is developed for interconnects enabled by a\ndata-driven learning algorithm accounting for variations of material\nproperties, heat sources and boundary conditions (BCs). The methodology is\nbased on the concepts of model order reduction and domain decomposition to\nconstruct a multi-block approach. A generic block model is built to represent a\ngroup of interconnect blocks that are used to wire standard cells in the\nintegrated circuits (ICs). The blocks in this group possess identical geometry\nwith various metal/via routings. The data-driven model reduction method is thus\napplied to learn material property variations induced by different metal/via\nroutings in the blocks, in addition to the variations of heat sources and BCs.\nThe approach is investigated in two very different settings. It is first\napplied to thermal simulation of a single interconnect block with similar BCs\nto those in the training of the generic block. It is then implemented in\nmulti-block thermal simulation of a FinFET IC, where the interconnect structure\nis partitioned into several blocks each modeled by the generic block model.\nAccuracy of the generic block model is examined in terms of the metal/via\nroutings, BCs and thermal discontinuities at the block interfaces.",
        "positive": "Giant barocaloric effects in natural rubber: A relevant step toward\n  solid-state cooling: Solid-state cooling based on i-caloric effects has shown to be a promising\nalternative to the conventional refrigeration devices. Only very recently, the\nresearch on barocaloric materials is receiving a deal of attention due to the\ndemonstration of giant barocaloric effects in shape-memory alloys. Regarding\npolymers, there is still a lack of literature, despite their high caloric\npotential. Thus, we present here giant barocaloric effects in natural rubber, a\nlow-cost and environmental friendly elastomer polymer. The maximum values of\nentropy and temperature changes are larger than those previously reported for\nany promising barocaloric material. Moreover, the huge normalized temperature\nchange and refrigerant capacity exhibited by natural rubber confirm its high\npotential for cooling applications. We also verify a relevant dependence of the\nbarocaloric effect on the glass transition in natural rubber. Our findings\nsuggest that commercial refrigeration devices based on barocaloric effects from\nelastomer polymers can be envisaged in the near future."
    },
    {
        "anchor": "Dielectric engineering of hot carrier generation by quantized plasmons\n  in embedded silver nanoparticles: Understanding and controlling properties of plasmon-induced hot carriers is a\nkey step towards next-generation photovoltaic and photocatalytic devices. Here,\nwe uncover a route to engineering hot-carrier generation rates of silver\nnanoparticles by designed embedding in dielectric host materials. Extending our\nrecently established quantum-mechanical approach to describe the decay of\nquantized plasmons into hot carriers we capture both external screening by the\nnanoparticle environment and internal screening by silver d-electrons through\nan effective electron-electron interaction. We find that hot-carrier generation\ncan be maximized by engineering the dielectric host material such that the\nenergy of the localized surface plasmon coincides with the highest value of the\nnanoparticle joint density of states. This allows us to uncover a path to\ncontrol the energy of the carriers and the amount produced, for example a large\nnumber of relatively low-energy carriers are obtained by embedding in strongly\nscreening environments.",
        "positive": "An analysis of (the lack of) slip transfer between near-cube oriented\n  grains in pure Al: Slip transfer across grain boundaries was studied in annealed polycrystalline\nAl foils deformed in uniaxial tension by means of the analysis of the slip\ntraces on the specimen surface. Grain orientations and selected grain boundary\nmisorientations were measured on both surfaces of the sample using electron\nback-scattered diffraction mapping. It was found that most of the grains were\nwithin 15{\\deg} of a cube orientation and approximately half of the grains\npercolated through the specimen thickness. The Luster-Morris m' parameter (that\ncan be computed from the surface grain orientation) was used to assess the\nlikelihood of slip transfer across boundaries. It was found that transfer\nacross grain boundaries was rare in near-cube oriented grains, and convincing\nevidence was only found when m' > 0.97, which corresponds to low-angle\nboundaries with <15{\\deg} misorientation. This behavior was explained by the\npresence of many active slip slips in near-cube oriented grains that favor\nself-accommodation of the grain shape to the evolving boundary conditions\nimposed by neighboring grains instead of promoting slip transfer across the\nboundary. These results indicate that the alignment between slip planes and\nslip directions across the boundary is not the only important metric to\ndetermine the threshold for slip transfer, as the particular details of\ndeformation in each grain (such as the number of available slip systems) also\nmust be considered."
    },
    {
        "anchor": "Chern insulators without band inversion in MoS2 monolayers with 3d\n  adatoms: Electronic and topological properties of MoS2 monolayers endowed with 3d\ntransition metal (TM) adatoms (V-Fe) are explored by using ab initio methods\nand k.p models. Without the consideration of the Hubbard U interaction, the V,\nCr, and Fe adatoms tend to locate on the top of the Mo atoms, while the most\nstable site for the Mn atom is at the hollow position of the Mo-S hexagon.\nAfter the Hubbard U is applied, the most stable sites of all the systems become\nthe top of the Mo atoms. Chern insulators without band inversion are achieved\nin these systems. The V and Fe adsorption systems are the best candidates to\nproduce the topological states. The k.p model calculations indicate that these\ntopological states are determined by the TM magnetism, the C3v crystal field\nfrom the MoS2 substrate, and the TM atomic spin-orbit coupling (SOC). The\nspecial two-meron pseudospin texture is found to contribute to the topology.\nThe apparent difference between the Berry curvatures for the V and Fe\nadsorption systems are also explored. Our results widen the understanding to\nthe Chern insulators and are helpful for the applications of the MoS2\nmonolayers in the future electronics and spintronics.",
        "positive": "First-principles calculation of scattering potentials of Si-Ge and Sn-Ge\n  dimers on Ge(001) surfaces: The scattering potential of the defects on Ge(001) surfaces is investigated\nby first-principles methods. The standing wave in the spatial map of the local\ndensity of states obtained by wave function matching is compared to the image\nof the differential conductance measured by scanning tunneling spectroscopy.\nThe period of the standing wave and its phase shift agree with those in the\nexperiment. It is found that the scattering potential becomes a barrier when\nthe electronegativity of the upper atom of the dimer is larger than that of the\nlower atom, while it acts as a well in the opposite case."
    },
    {
        "anchor": "Optical Rotatory Dispersion of $\u03b1$-quartz: It is shown that some formulae describing optical rotatory dispersion of\n$\\alpha$-quartz with the aid of two Drude's terms reduce to the combined\nformula containing one Drude's and one Chandrasekhar's term. Comparison of\nvarious formulae describing the experimental data of $\\alpha$-quartz leads to\nthe conclusion that the optical activity of this crystal is due to its crystal\nstructure only, that means the optical activity is not of molecular origin.\nFurther the rotatory strengths are discussed with the regard to coupled\noscillator model and to the structure of $\\alpha$-quartz.",
        "positive": "Dilute moment n-type ferromagnetic semiconductor Li(Zn,Mn)As: We propose to replace Ga in (Ga,Mn)As with Li and Zn as a route to high Curie\ntemperature, carrier mediated ferromagnetism in a dilute moment n-type\nsemiconductor. Superior material characteristics, rendering Li(Zn,Mn)As a\nrealistic candidate for such a system, include unlimited solubility of the\nisovalent substitutional Mn impurity and carrier concentration controlled\nindependently of Mn doping by adjusting Li-(Zn,Mn) stoichiometry. Our\npredictions are anchored by detail ab initio calculations and comparisons with\nthe familiar and directly related (Ga,Mn)As, by the microscopic physical\npicture we provide for the exchange interaction between Mn local moments and\nelectrons in the conduction band, and by analysis of prospects for the\ncontrolled growth of Li(Zn,Mn)As materials."
    },
    {
        "anchor": "Van der Waals contribution to the inelastic atom-surface scattering: A calculation of the inelastic scattering rate of Xe atoms on Cu(111) is\npresented. We focus in the regimes of low and intermediate velocities, where\nthe energy loss is mainly associated to the excitation electron-hole pairs in\nthe substrate. We consider trajectories parallel to the surface and restrict\nourselves to the Van der Waals contribution. The decay rate is calculated\nwithin a self-energy formulation. The effect of the response function of the\nsubstrate is studied by comparing the results obtained with two different\napproaches: the Specular Reflection Model and the Random Phase Approximation.\nIn the latter, the surface is described by a finite slab and the wave functions\nare obtained from a one-dimensional model potential that describes the main\nfeatures of the surface electronic structure while correctly retains the\nimage-like asymptotic behaviour. We have also studied the influence of the\nsurface state on the calculation, finding that it represents around 50% of the\ntotal probability of electron-hole pairs excitation.",
        "positive": "Growth and characterization of $\u03b1$-Sn thin films on In- and Sb-rich\n  reconstructions of InSb(001): $\\alpha$-Sn thin films can exhibit a variety of topologically non-trivial\nphases. Both studying the transitions between these phases and making use of\nthese phases in eventual applications requires good control over the electronic\nand structural quality of $\\alpha$-Sn thin films. $\\alpha$-Sn growth on InSb\noften results in out-diffusion of indium, a p-type dopant. By growing\n$\\alpha$-Sn via molecular beam epitaxy on the Sb-rich c(4$\\times$4) surface\nreconstruction of InSb(001) rather than the In-rich c(8$\\times$2), we\ndemonstrate a route to substantially decrease and minimize this indium\nincorporation. The reduction in indium concentration allows for the study of\nthe surface and bulk Dirac nodes in $\\alpha$-Sn via angle-resolved\nphotoelectron spectroscopy without the common approaches of bulk doping or\nsurface dosing, simplifying topological phase identification. The lack of\nindium incorporation is verified in angle-resolved and -integrated ultraviolet\nphotoelectron spectroscopy as well as in clear changes in the Hall response."
    },
    {
        "anchor": "Strongly Modulated Ambipolar Characteristics of Few-layer Black\n  Phosphorus in Oxygen: Two-dimensional black phosphorus has been configured as field-effect\ntransistors, showing an intrinsic symmetric ambipolar transport characteristic.\nHere, we demonstrate the strongly modulated ambipolar characteristics of\nfew-layer black phosphorus in oxygen. Pure oxygen exposure can dramatically\ndecrease the electron mobility of black phosphorus without degrading the hole\ntransport. The transport characteristics can be nearly recovered upon annealing\nin Argon. This reveals that oxygen molecules are physisorbed on black\nphosphorus. In contrast, oxygen exposure upon light illumination exhibits a\nsignificant attenuation for both electron and hole transport, originating from\nthe photoactivated oxidation of black phosphorus, which is corroborated by in\nsitu X-ray photoelectron spectroscopy characterization. Our findings clarify\nthe predominant role of oxygen in modulating ambipolar characteristics of black\nphosphorus, thereby providing deeper insight to the design of black phosphorus\nbased complementary electronics.",
        "positive": "X-ray Absorption Near Edge Structure of FePt nanoclusters: X-ray Absorption Near Edge Structure [XANES] of FePt nanoclusters has been\nstudied using a full multiple scattering, self-consistent field [SCF],\nreal-space Green`s function approach realized via the powerful ab initio FEFF8\ncode. One purpose of our study is to determine the sensitivity of Pt L3 edge\nwith respect to the size and shape of the FePt nanoclusters. We also give the\nresults of the calculations with respect to the Fe L3 edge. Calculations are\nmade with and without core-hole for two main reasons, to check and cross-check\nthe FEFF code and also since in some cases it is known such as Pt clusters that\nbetter results are obtained without the core-hole. This is mainly because the\nscreening electron will occupy empty d or f states and correspondingly reduce\nthe white line intensity."
    },
    {
        "anchor": "Better band gaps for wide-gap semiconductors from a locally corrected\n  exchange-correlation potential that nearly eliminates self-interaction errors: This work constitutes a comprehensive and improved account of\nelectronic-structure and mechanical properties of silicon-nitride (Si3N4)\npolymorphs via van Leeuwen and Baerends (LB) exchange-corrected local density\napproximation (LDA) that enforces the exact exchange potential asymptotic\nbehavior. The calculated lattice constant, bulk modulus, and electronic band\nstructure of Si3N4 polymorphs are in good agreement with experimental results.\nWe also show that, for a single electron in a hydrogen atom, spherical well, or\nharmonic oscillator, the LB-corrected LDA reduces the (self-interaction) error\nto exact total energy to ~10%, a factor of three to four lower than standard\nLDA, due to a dramatically improved representation of the exchange-potential.",
        "positive": "Zero Poisson' s Ratio and Suppressed Mechanical Anisotropy in BP/SnSe\n  Van der Waals Heterostructure: A First-principles Study: Black phosphorene and its analogs have attracted intensive attention due to\ntheir unique puckered structures, anisotropic characteristics, and negative\nPoisson's ratio. The van der Waals heterostructures assembly by stacking\ndifferent materials may show novel physical properties which the parent\nmaterials don't possess. In this work, the first-principles calculations were\nperformed to study the mechanical properties of the BP/SnSe van der Waals\nheterostructure. Interestingly, a near-zero Poisson's ratio vzx was found in\nBP/SnSe heterostructure. In addition, compared to the parent materials BP and\nSnSe with strong in-plane anisotropic mechanical properties, the BP/SnSe\nheterostructure shows strongly suppressed anisotropy. Our findings suggest that\nthe vdW heterostructure could show quite different mechanical properties from\nthe parent materials and provide new opportunities for the mechanical\napplications of the heterostructures."
    },
    {
        "anchor": "Three-dimensional topological insulators: A review on host materials: In recent years, three-dimensional topological insulators (3DTI) as a novel\nstate of quantum matter have become a hot topic in the fields of condensed\nmatter physics and materials sciences. To fulfill many spectacularly novel\nquantum phenomena predicted in 3DTI, real host materials are of crucial\nimportance. In this review paper, we first introduce general methods of\nsearching for new 3DTI based on the density-functional theory. Then, we review\nthe recent progress on materials realization of 3DTI including simple elements,\nbinary compounds, ternary compounds, and quaternary compounds. In these\npotential host materials, some of them have already been confirmed by\nexperiments while the others are not yet. The 3DTI discussed here does not\ncontain the materials with strong electron-electron correlation. Lastly, we\ngive a brief summary and some outlooks in further studies.",
        "positive": "Linear and quadratic magnetoresistance in the semimetal SiP2: Multiple mechanisms for extremely large magnetoresistance (XMR) found in many\ntopologically nontrivial/trivial semimetals have been theoretically proposed,\nbut experimentally it is unclear which mechanism is responsible in a particular\nsample. In this article, by the combination of band structure calculations,\nnumerical simulations of magnetoresistance (MR), Hall resistivity and de\nHaas-van Alphen (dHvA) oscillation measurements, we studied the MR anisotropy\nof SiP$_{2}$ which is verified to be a topologically trivial, incomplete\ncompensation semimetal. It was found that as magnetic field, $H$, is applied\nalong the $a$ axis, the MR exhibits an unsaturated nearly linear $H$\ndependence, which was argued to arise from incomplete carriers compensation.\nFor the $H$ $\\parallel$ [101] orientation, an unsaturated nearly quadratic $H$\ndependence of MR up to 5.88 $\\times$ 10$^{4}$$\\%$ (at 1.8 K, 31.2 T) and\nfield-induced up-turn behavior in resistivity were observed, which was\nsuggested due to the existence of hole open orbits extending along the $k_{x}$\ndirection. Good agreement of the experimental results with the simulations\nbased on the calculated Fermi surface (FS) indicates that the topology of FS\nplays an important role in its MR."
    },
    {
        "anchor": "Phonon-limited carrier mobilities and Hall factors in 4H-SiC from first\n  principles: Charge carrier mobility is at the core of semiconductor materials and devices\noptimization, and Hall measurement is one of the most important techniques for\nits characterization. The Hall factor, defined as the ratio between Hall and\ndrift mobilities, is of particular importance. Here we study the effect of\nanisotropy by computing the drift and Hall mobility tensors of a\ntechnologically important wide-band-gap semiconductor, 4H-silicon carbide\n(4H-SiC) from first principles. With $GW$ electronic structure and \\textit{ab\ninitio} electron-phonon interactions, we solve the Boltzmann transport equation\nwithout fitting parameters. The calculated electron and hole mobilities agree\nwith experimental data. The electron Hall factor strongly depends on the\ndirection of external magnetic field $\\mathbf{B}$, and the hole Hall factor\nexhibits different temperature dependency for $\\mathbf{B}\\parallel c$ and\n$\\mathbf{B}\\perp c$. We explain this by the different equienergy surface shape\narising from the anisotropic and non-parabolic band structure, together with\nthe energy-dependent electron-phonon scattering.",
        "positive": "Influence of simple metals on the stability of $\\langle a\\rangle$ basal\n  screw dislocations in hexagonal titanium alloys: Basal slip acts as a secondary deformation mode in hexagonal close-packed\ntitanium and becomes one of the primary mechanisms in titanium alloyed with\nsimple metals. As these solute elements also lead to a pronounced reduction of\nthe energy of the basal stacking fault, one can hypothesize that they promote\nbasal dissociation of dislocations which can then easily glide in the basal\nplanes. Here, we verify the validity of this hypothesis using ab initio\ncalculations to model the interaction of a screw dislocation with indium (In)\nand tin (Sn). These calculations confirm that these simple metals are attracted\nby the stacking fault existing in the dislocation core when it is dissociated\nin a basal plane, but this interaction is not strong enough to stabilize a\nplanar configuration, even for a high solute concentration in the core. Energy\nbarrier calculations reveal that basal slip, in the presence of In and Sn,\nproceeds without any planar dissociation, with the dislocation being spread in\npyramidal and prismatic planes during basal slip like in pure Ti. The\ncorresponding energy barrier is higher in presence of solute atoms, showing\nthat In and Sn do not ease basal slip but increase the corresponding lattice\nfriction. This strengthening of basal slip by solute atoms is discussed in view\nof available experimental data."
    },
    {
        "anchor": "Superconductivity at 161 K in Thorium Hydride $ThH_{10}$: Synthesis and\n  Properties: Here we report targeted high-pressure synthesis of two novel high-$T_C$\nhydride superconductors, $P6_3/mmc$-$ThH_9$ and $Fm\\bar{3}m$-$ThH_{10}$, with\nthe experimental critical temperatures ($T_C$) of 146 K and 159-161 K and upper\ncritical magnetic fields ($\\mu$$H_C$) 38 and 45 Tesla at pressures 170-175\nGigapascals, respectively. Superconductivity was evidenced by the observation\nof zero resistance and a decrease of $T_C$ under external magnetic field up to\n16 Tesla. This is one of the highest critical temperatures that has been\nachieved experimentally in any compounds, along with such materials as\n$LaH_{10}$, $H_3S$ and $HgBa_2Ca_xCu_2O_{6+z}$. Our experiments show that\n$fcc$-$ThH_{10}$ has stabilization pressure of 85 GPa, making this material\nunique among all known high-$T_C$ metal polyhydrides. Two recently predicted\nTh-H compounds, $I4/mmm$-$ThH_4$ (> 86 GPa) and $Cmc2_1$-$ThH_6$ (86-104 GPa),\nwere also synthesized. Equations of state of obtained thorium polyhydrides were\nmeasured and found to perfectly agree with the theoretical calculations. New\nphases were examined theoretically and their electronic, phonon, and\nsuperconducting properties were calculated.",
        "positive": "Electrochemical and mechanical behaviors of dissimilar friction stir\n  welding between 5086 and 6061 aluminum alloy: The electrochemical behavior and mechanical properties of friction stir\nwelded AA5086 and AA6061 Al alloys were investigated. Micro-hardness\nmeasurements and tensile tests showed that the heat-affected zone (HAZ) in\nAA6061 had minimum hardness value (i.e., 88 HV) and served as failure site in\nthe dissimilar weld. Corrosion testing revealed that the minimum value of Icorr\nappeared in the HAZ 5086 (0.54 uA/cm2) and HAZ 5086 was most resistant to\ncorrosion. The AA 5086 side of the weld showed better corrosion resistance than\nthe AA 6061 side."
    },
    {
        "anchor": "Book-keeping of Ion and Electron Currents in the Point Defect Model and\n  Role of an Electron Channel at the metal/film Interface in Determining the\n  Forms of the metal-film potential and the film-solution potential drops: In any consistent electrochemical systems model that addresses more than one\ninterface, the total current at the interfaces should be equal to one another\nand to the current in the external circuit. The point defect model of Macdonald\nand co-workers fails to recognize this basic requirement. Hence there is no\nassurance that currents predicted by the PDM will be the same at the metal/film\nand the film/solution interfaces. This deficiency is corrected in the present\nwork. Besides, The point defect model lacks a proper book-keeping of ion and\nelectron currents and in particular missed the role of a purely electron\nchannel (e-channel) at the metal/film interface [1]. In this work we describe\nthis book-keeping, include the e-channel and show how this affects the forms of\nthe metal-film and film-solution potential drops.",
        "positive": "Machine Learning Based Prediction of Polaron-Vacancy Patterns on the\n  TiO$_2$(110) Surface: The multifaceted physics of oxides is shaped by their composition and the\npresence of defects, which are often accompanied by the formation of polarons.\nThe simultaneous presence of polarons and defects, and their complex\ninteractions, pose challenges for first-principles simulations and experimental\ntechniques. In this study, we leverage machine learning and a first-principles\ndatabase to analyze the distribution of surface oxygen vacancies (V$_{\\rm O}$)\nand induced small polarons on rutile TiO$_2$(110), effectively disentangling\nthe interactions between polarons and defects. By combining neural-network\nsupervised learning and simulated annealing, we elucidate the inhomogeneous\nV$_{\\rm O}$ distribution observed in scanning probe microscopy (SPM). Our\ninnovative approach allows us to understand and predict defective surface\npatterns at previously inaccessible length scales, identifying the specific\nrole of individual types of defects. Specifically, surface-polaron-stabilizing\nV$_{\\rm O}$-configurations are identified, which could have consequences for\nsurface reactivity."
    },
    {
        "anchor": "Effects of the Electronic Structure, Phase Transition, and Localized\n  Dynamics of Atoms in the Formation of Tiny Particles of Gold: In addition to the self-governing properties, tiny metallic colloids are the\nbuilding blocks of larger particles. This topic has been the subject of many\nstudies. This work discusses the results of three different experiments.\nAttained dynamics of the atoms also play a role in developing tiny particles.\nAtoms at the solution surface can also bind by the nano energy packets. Arrays\nof atoms convert into structures of smooth elements. When electron streams\nimpinge on gold atoms at a fixed angle, atoms can elongate further. Traveling\nphotons along the interface affect the atomic arrays. Gold atoms can also\ndevelop different tiny particles in solution. Various factors to their\ndevelopment contribute. The present work also considers the analyses of some\ntiny-sized particles. In the processing of tiny-metallic colloids at different\nparameters, major leveled modifications of atoms took place. The study also\ndiscusses the influence of traveling photons along the matter-solution\ninterface. This study highlights the fundamental process of developing a\nvariety of tiny particles. Several possibilities may open through the\npulse-based process to develop engineered materials.",
        "positive": "Theoretical Investigation of Charge Transfer Between Two Defects in a\n  Wide-Bandgap Semiconductor: Charge traps in the semiconductor bulk (bulk charge traps) make it difficult\nto predict the electric field within wide-bandgap semiconductors. The issue is\nthe daunting number of bulk charge-trap candidates which means the treatment of\nbulk charge traps is generally qualitative or uses generalized models that do\nnot consider the trap's particular electronic structure. The electric field\nwithin a wide-bandgap semiconductor is nonetheless a crucial quantity in\ndetermining the operation of semiconductor devices and the performance of\nsolid-state single-photon emitters embedded within the semiconductor devices.\nIn this work we accurately compute the average electric field measured at the\nlocation of N$V^-$ charged defects for the substitutional N (N$_\\text{C}$)\nconcentration of $n_{\\text{N}_\\text{C}} \\approx 1.41\\times10^{18}$ cm$^{-3}$\nfor the commonly used oxygen-terminated diamond (see [D. A. Broadway $et$\n$al$., Nature Electronics 1, 502 (2018)]). We achieve this result by evaluating\nthe leading-order contribution to the electric field far away from the surface,\nwhich comes from the N$_\\text{C}$ defects that induce the ionization of the\nN$V^-$. Our results use density-functional theory (DFT) and the principle of\nband bending. Our work has the potential to aid both in the prediction of the\nfunctioning of semiconductor devices and in the prediction and correction of\nthe spectral diffusion that often plagues the optical frequencies of\nsolid-state single-photon emitters upon repeated photoexcitation measurements.\nOur results for the timescales involved in thermally driven charge transfer\nalso have the potential to aid in investigations of charge dynamics."
    },
    {
        "anchor": "Electronic structure of spheroidal fullerenes: Graphite is an example of a layered material that can be bent to form\nfullerenes which promise important applications in electronic nanodevices. The\nspheroidal geometry of a slightly elliptically deformed sphere was used as a\npossible approach to fullerenes. We assumed that for a small deformation the\neccentricity of the spheroid is much more smaller then one. We are interested\nin the elliptically deformed fullerenes C70 as well as in C60 and its spherical\ngeneralizations like big C240 and C540 molecules. In the next study the\nexpanded field-theory model was proposed to study the electronic states near\nthe Fermi energy in spheroidal fullerenes. The low energy electronic wave\nfunctions obey a two-dimensional Dirac equation on a spheroid with two kinds of\ngauge fluxes taken into account. We shown exactly how a small deformation of\nspherical fullerenes provokes an appearance of fine structure in the electronic\nenergy spectrum as compared to the spherical case. The effect of a weak uniform\nmagnetic field on the electronic structure of slightly deformed fullerene\nmolecules was also studied. We shown that the fine structure of the electronic\nenergy spectrum is very sensitive to the orientation of the magnetic field. We\nfound that the magnetic field pointed in the x direction does not influence the\nfirst electronic level whereas it causes a splitting of the second energy\nlevel.",
        "positive": "What can the activation energy tell about the energetics at grain\n  boundaries in polycrystalline organic films?: Charge-carrier transport at the semiconductor-gate dielectric interface in\norganic field-effect transistors is critically dependent on the degree of\ndisorder in the typically semi-crystalline semiconductor layer. Charge trapping\ncan occur at the interface as well as in the current-carrying semiconductor\nlayer itself. A detailed and systematic understanding of the role of grain\nboundaries between crystallites and how to avoid their potentially detrimental\neffects is still an important focus of research in the organic electronics\ncommunity. A typical macroscopic measurement technique to extract information\nabout the energetics of the grain boundaries is an activation energy\nmeasurement. Here, we compare detailed experiments on the energetic properties\nof monolayer thin films implemented in organic field-effect transistors, having\ncontrolled numbers of grain boundaries within the channel region to kinetic\nMonte-Carlo simulations of charge-carrier transport to elucidate the influence\nof grain boundaries on the extracted activation energies. Two important\nfindings are: 1) whereas the energy at the grain boundary does not change with\nthe number of grain boundaries in a thin film, both the measured and simulated\nactivation energy increases with the number of grain boundaries. 2) In\nsimulations where both energy barriers and valleys are present at the grain\nboundaries there is no systematic relation between the number of grain\nboundaries and extracted activation energies. We conclude, that a macroscopic\nmeasurement of the activation energy can serve as general quality indicator of\nthe thin film, but does not allow microscopic conclusions about the energy\nlandscape of the thin film."
    },
    {
        "anchor": "Interpretation of experimental evidence of the topological Hall effect: The topological Hall effect in magnetic materials is considered the ultimate\ntrademark of the skyrmion phase. The phenomenon is identified by distinct\nnon-monotonic features in the Hall effect signal presumed to be the evidence of\nthe topological origin. It is demonstrated here that similar features,\nunrelated to the skyrmion physics, arise in heterogeneous ferromagnets when\ncomponents of the material exhibit the extraordinary Hall effect with opposite\npolarities. Relevance of this mechanism to the published data is discussed.",
        "positive": "Molecular transport through capillaries made with atomic-scale precision: Nanometre-scale pores and capillaries have long been studied because of their\nimportance in many natural phenomena and their use in numerous applications. A\nmore recent development is the ability to fabricate artificial capillaries with\nnanometre dimensions, which has enabled new research on molecular transport and\nled to the emergence of nanofluidics. But surface roughness in particular makes\nit challenging to produce capillaries with precisely controlled dimensions at\nthis spatial scale. Here we report the fabrication of narrow and smooth\ncapillaries through van der Waals assembly, with atomically flat sheets at the\ntop and bottom separated by spacers made of two-dimensional crystals with a\nprecisely controlled number of layers. We use graphene and its multilayers as\narchetypal two-dimensional materials to demonstrate this technology, which\nproduces structures that can be viewed as if individual atomic planes had been\nremoved from a bulk crystal to leave behind flat voids of a height chosen with\natomic-scale precision. Water transport through the channels, ranging in height\nfrom one to several dozen atomic planes, is characterized by unexpectedly fast\nflow (up to 1 metre per second) that we attribute to high capillary pressures\n(about 1,000 bar) and large slip lengths. For channels that accommodate only a\nfew layers of water, the flow exhibits a marked enhancement that we associate\nwith an increased structural order in nanoconfined water. Our work opens up an\navenue to making capillaries and cavities with sizes tunable to {\\aa}ngstr\\\"om\nprecision, and with permeation properties further controlled through a wide\nchoice of atomically flat materials available for channel walls."
    },
    {
        "anchor": "Anisotropic thermoelectric properties of EuCd$_{2}$As$_{2}$ : An\n  Ab-initio study: In search of better thermoelectric materials, we have systematically\ninvestigated the thermoelectric properties of a 122 Zintl phase compound\nEuCd$_{2}$As$_{2}$ using \\textit{ab-initio} density functional theory and\nsemi-classical Boltzmann transport theory within constant relaxation time\napproximation. Considering the ground state magnetic structure which is A-type\nantiferromagnetic (A-AFM) and non-magnetic (NM) structure, we evaluated various\nthermoelectric parameters such as Seebeck coefficient, electrical and thermal\nconductivity, power factor and figure of merit (ZT) as function temperature as\nwell as chemical potential. Almost all thermoelectric parameters show\nanisotropy between $xx$ and $zz$ directions which is stronger in case of A-AFM\nthan in NM. Both A-AFM and NM phase of the compound display better\nthermoelectric performance when hole doped. We observed high Seebeck\ncoefficient and low electronic thermal conductivity in A-AFM phase along $zz$\ndirection. The remarkably high ZT of 1.79 at 500 K in A-AFM phase and ZT$\\sim$1\nin NM phase suggest that EuCd$_{2}$As$_{2}$ is a viable thermoelectric material\nwhen p-doped.",
        "positive": "Ferromagnetism in Insulating, Doped Diluted Magnetic Semiconductors: We report results of a Monte Carlo study of doped, diluted magnetic\nsemiconductors in the low carrier density (insulating) regime. We find that the\nsystem undergoes a transition from a paramagnet at high temperatures to a\nferromagnet at low temperatures. However, in strong contrast to uniform\nsystems, disorder effects dominate the entire collective behavior, leading to\nvery unconventional properties such as (1) magnetization curves that cannot be\ndescribed by theories based on critical fluctuations, or on spin wave analysis\nover any significant fraction of the phase diagram; (2) a large peak in\nsusceptibilty well below the ordering temperature; and (3) specific heat curves\nthat point out the inadequacy of a classical Heisenberg model for spin-5/2 Mn\nions. A picture of percolating magnetic polarons appears to describe the data\nwell, and leads to a prescription for correcting the unphysical results of the\nclassical continuous spin model in terms of a discrete vector model."
    },
    {
        "anchor": "Wave propagation and homogenization in 2D and 3D lattices: a\n  semi-analytical approach: Wave motion in two- and three-dimensional periodic lattices of beam members\nsupporting longitudinal and flexural waves is considered. An analytic method\nfor solving the Bloch wave spectrum is developed, characterized by a\ngeneralized eigenvalue equation obtained by enforcing the Floquet condition.\nThe dynamic stiffness matrix is shown to be explicitly Hermitian and to admit\npositive eigenvalues. Lattices with hexagonal, rectangular, tetrahedral and\ncubic unit cells are analyzed. The semi-analytical method can be asymptotically\nexpanded for low frequency yielding explicit forms for the Christoffel matrix\ndescribing wave motion in the quasistatic limit.",
        "positive": "Magnetoresistance in YBi and LuBi semimetals due to nearly perfect\n  carrier compensation: Monobismuthides of yttrium and lutetium are shown as new representatives of\nmaterials which exhibit extreme magnetoresistance and magnetic-field-induced\nresistivity plateau. At low temperatures and in magnetic field of 9T the\nmagnetoresistance attains the order of magnitude of 10,000% and 1,000%, on YBi\nand LuBi, respectively. Our thorough examination of electron transport\nproperties of both compounds show that observed features are the consequence of\nnearly perfect carrier compensation rather than of possible nontrivial topology\nof electronic states. The field-induced plateau of electrical resistivity can\nbe explained with Kohler scaling. Anisotropic multi-band model of electronic\ntransport describes very well the magnetic field dependence of electrical\nresistivity and Hall resistivity. Data obtained from the Shubnikov-de Haas\noscillations analysis also confirm that Fermi surface of each compound contains\nalmost equal amounts of holes and electrons. First-principle calculations of\nelectronic band structure are in a very good agreement with the experimental\ndata."
    },
    {
        "anchor": "Ionic Charge Imbalance in Perovskite Solar Cells: Ion migration in perovskite solar cells is usually analyzed and understood in\nterms of charge neutrality condition. However, several recent reports indicate\npossibility of ionic imbalance in the active layer due to external ion\nmigration and/or chemical reactions. In this context, here we explore the\ninfluence of ionic charge neutrality on the performance of perovskite solar\ncells. Our results indicate that ionic imbalance leads to an asymmetry in the\ndevice electrostatics, which have interesting implications on the impact of\nmaterial/interface degradation, hysteresis, and finally on the long-term\nstability and influence of optimal device architecture (NIP vs. PIN).",
        "positive": "Lattice dynamics in the paraelectric phase of PbHfO$_3$ studied by\n  inelastic X-ray scattering: We report the results of an inelastic X-ray scattering study of the lattice\ndynamics in the paraelectric phase of the antiferroelectric lead hafnate\nPbHfO$_3$. The study reveals an avoided crossing between the transverse\nacoustic and transverse optic phonon modes propagating along the [1 1 0]\ndirection with [1 -1 0] polarization. The static susceptibility with respect to\nthe generally incommensurate modulations is shown to increase on cooling for\nthe entire $\\Gamma$-M direction. We consider different approaches to the data\nanalysis that correspond to different models for the temperature evolution of\nthe dynamic susceptibility function. A number of similarities and differences\nbetween the lattice dynamics of PbHfO$_3$ and PbZrO$_3$ are described."
    },
    {
        "anchor": "Three dimensional valency mapping in CeO$_{2-x}$ nanocrystals: Using electron tomography in combination with spatially resolved electron\nenergy-loss spectroscopy at high energy resolution, we are able to map the\nvalency of the Ce ions in CeO$_{2-x}$ nanocrystals. Our three-dimensional\nresults show a clear facet-dependent reduction shell at the surface of ceria\nnanoparticles; {111} surface facets show a low surface reduction, whereas at\n{001} surface facets the cerium ions are more likely to be reduced over a\nlarger surface shell. The novelty of this generic tomographic technique is that\nit allows a full three dimensional datacube to be reconstructed, containing a\nfull electron energy-loss spectrum in each voxel. The ability to extract an\nelectron energy-loss spectrum in each point of a reconstructed datacube,\nenables the three-dimensional investigation of a plethora of material-specific\nphysical properties such as valency, chemical composition, oxygen coordination\nor bond lengths. These experiments will trigger the synthesis of nanomaterials\nwith improved properties and the design of nanostructures with novel\nfunctionalities.",
        "positive": "Interplay between phonons and anisotropic elasticity drives negative\n  thermal expansion in PbTiO$_3$: We use first-principles theory to show that the ingredients assumed to be\nessential to the occurrence of negative thermal expansion (NTE) -- rigid unit\nphonon modes with negative Gr\\\"{u}neisen parameters -- are neither sufficient\nnor necessary for a material to undergo NTE. Instead, we find that NTE in\nPbTiO$_3$ involves a delicate interplay between the phonon properties of a\nmaterial (Gr\\\"{u}neisen parameters) and its anisotropic elasticity. These\nunique insights open new avenues in our fundamental understanding of the\nthermal properties of materials, and in the search for NTE in new materials\nclasses."
    },
    {
        "anchor": "Hot Phonon and Carrier Relaxation in Si(100) Determined by Transient\n  Extreme Ultraviolet Spectroscopy: The thermalization of hot carriers and phonons gives direct insight into the\nscattering processes that mediate electrical and thermal transport. Obtaining\nthe scattering rates for both hot carriers and phonons currently requires\nmultiple measurements with incommensurate timescales. Here, transient\nextreme-ultraviolet (XUV) spectroscopy on the silicon 2p core level at 100 eV\nis used to measure hot carrier and phonon thermalization in Si(100) from tens\nof femtoseconds to 200 ps following photoexcitation of the indirect transition\nto the {\\Delta} valley at 800 nm. The ground state XUV spectrum is first\ntheoretically predicted using a combination of a single plasmon pole model and\nthe Bethe-Salpeter equation (BSE) with density functional theory (DFT). The\nexcited state spectrum is predicted by incorporating the electronic effects of\nphoto-induced state-filling, broadening, and band-gap renormalization into the\nground state XUV spectrum. A time-dependent lattice deformation and expansion\nis also required to describe the excited state spectrum. The kinetics of these\nstructural components match the kinetics of phonons excited from the\nelectron-phonon and phonon-phonon scattering processes following\nphotoexcitation. Separating the contributions of electronic and structural\neffects on the transient XUV spectra allows the carrier population, the\npopulation of phonons involved in inter- and intra-valley electron-phonon\nscattering, and the population of phonons involved in phonon-phonon scattering\nto be quantified as a function of delay time.",
        "positive": "Hole-doped cobalt-based Heusler phases as prospective high-performance\n  high-temperature thermoelectrics: Materials design based on first-principles electronic calculations has proven\na fruitful strategy to identify new thermoelectric materials with a favorable\nfigure of merit. Recent electronic structure calculations predict that in\ncobalt-based half-Heusler systems a power factor higher than in CoTiSb can be\nachieved upon p-type doping of CoVSn, CoNbSn, CoTaSn, CoMoIn, and CoWIn. Here,\nusing a first-principles approach and semi-classical Boltzmann transport\ntheory, we investigate the electrical and thermal transport properties of these\nmaterials. The calculated thermal conductivity at room temperature of all the\nsystems is lower than that of CoTiSb, with CoMoIn and CoWIn having an almost\n3-fold lower thermal conductivity than CoTiSb. We also provide conservative\nestimates of the figure of merit for these systems which all turn out to be\nhigher than in CoTiSb and to have a maximum value for CoWIn."
    },
    {
        "anchor": "Spin-Torque Diode Measurements of MgO-Based Magnetic Tunnel Junctions\n  with Asymmetric Electrodes: We present a detailed study of the spin-torque diode effect in\nCoFeB/MgO/CoFe/NiFe magnetic tunnel junctions. From the evolution of the\nresonance frequency with magnetic field at different angles, we clearly\nidentify the free-layer mode and find an excellent agreement with simulations\nby taking into account several terms for magnetic anisotropy. Moreover, we\ndemonstrate the large contribution of the out-of-plane torque in our junctions\nwith asymmetric electrodes compared to the in-plane torque. Consequently, we\nprovide a way to enhance the sensitivity of these devices for the detection of\nmicrowave frequency.",
        "positive": "Microscopic theory of singlet exciton fission. I. General formulation: Singlet fission, a spin-allowed energy transfer process generating two\ntriplet excitons from one singlet exciton, has the potential to dramatically\nincrease the efficiency of organic solar cells. However, the dynamical\nmechanism of this phenomenon is not fully understood and a complete,\nmicroscopic theory of singlet fission is lacking. In this work, we assemble the\ncomponents of a comprehensive microscopic theory of singlet fission that\nconnects excited state quantum chemistry calculations with finite-temperature\nquantum relaxation theory. We elaborate on the distinction between localized\ndiabatic and delocalized adiabatic bases for the interpretation of singlet\nfission experiments in both the time and frequency domains. We discuss various\napproximations to the exact density matrix dynamics and propose Redfield theory\nas an ideal compromise between speed and accuracy for the detailed\ninvestigation of singlet fission in dimers, clusters, and crystals.\nInvestigations of small model systems based on parameters typical of singlet\nfission demonstrate the numerical accuracy and practical utility of this\napproach."
    },
    {
        "anchor": "Elastic constants of polycrystalline steel evaluated with laser\n  generated surface acoustic waves: We report on a laser generated and detected surface acoustic wave method for\nevaluating the elastic constants of micro-crystals composing polycrystalline\nsteel. The method is based on the measurement of surface wave velocities in\nmany micro-crystals oriented randomly relative to both the wave propagation\ndirection and the sample surface. The surface wave velocity distribution is\nobtained experimentally thanks to the scanning potentiality of the method and\nis then compared to the theoretical one. The inverse problem can then be\nsolved, leading to the determination of three elastic constants of the cubic\nsymmetry micro-crystals. Extensions of the method to the characterization of\ntexture, preferential orientation of micro-crystals or welds could be foreseen.",
        "positive": "Non-adiabatic effects during the dissociative adsorption of O2 at\n  Ag(111)? A first-principles divide and conquer study: We study the gas-surface dynamics of O2 at Ag(111) with the particular\nobjective to unravel whether electronic non-adiabatic effects are contributing\nto the experimentally established inertness of the surface with respect to\noxygen uptake. We employ a first-principles divide and conquer approach based\non an extensive density-functional theory mapping of the adiabatic potential\nenergy surface (PES) along the six O2 molecular degrees of freedom. Neural\nnetworks are subsequently used to interpolate this grid data to a continuous\nrepresentation. The low computational cost with which forces are available from\nthis PES representation allows then for a sufficiently large number of\nmolecular dynamics trajectories to quantitatively determine the very low\ninitial dissociative sticking coefficient at this surface. Already these\nadiabatic calculations yield dissociation probabilities close to the scattered\nexperimental data. Our analysis shows that this low reactivity is governed by\nlarge energy barriers in excess of 1.1 eV very close to the surface.\nUnfortunately, these adiabatic PES characteristics render the dissociative\nsticking a rather insensitive quantity with respect to a potential spin or\ncharge non-adiabaticity in the O2-Ag(111) interaction. We correspondingly\nattribute the remaining deviations between the computed and measured\ndissociation probabilities primarily to unresolved experimental issues with\nrespect to surface imperfections."
    },
    {
        "anchor": "Phonon Spectroscopy with Sub-meV Resolution by Femtosecond X-ray Diffuse\n  Scattering: We present a reconstruction of the transverse acoustic phonon dispersion of\ngermanium from femtosecond time-resolved x-ray diffuse scattering measurements\nat the Linac Coherent Light Source. We demonstrate an energy resolution of 0.3\nmeV with momentum resolution of 0.01 nm^-1 using 10 keV x-rays with a bandwidth\nof ~ 1 eV. This high resolution was achieved simultaneously for a large section\nof reciprocal space including regions closely following three of the principle\nsymmetry directions. The phonon dispersion was reconstructed with less than\nthree hours of measurement time, during which neither the x-ray energy, the\nsample orientation, nor the detector position were scanned. These results\ndemonstrate how time-domain measurements can complement conventional frequency\ndomain inelastic scattering techniques.",
        "positive": "Reply to the Comment on 'Unraveling Photoinduced Spin Dynamics in the\n  Topological Insulator Bi2Se3': Reply to the Comment [arXiv:1609.04476] on a recent work in PRL [Phys. Rev.\nLett. 116, 036601 (2016), arXiv:1511.02994v2]."
    },
    {
        "anchor": "Thin Film Substrates from the Raman spectroscopy point of view: We have investigated ten standard single crystal substrates of complex oxides\non the account of their applicability in the Raman spectroscopy based thin film\nresearch. In this study we suggest a spectra normalization procedure that\nutilizes a comparison of the substrate Raman spectra to those of\nwell-established Raman reference materials. We demonstrate that MgO, LaGaO3,\n(LaAlO3)_0.3(Sr2AlTaO6)_0.7 (LSAT), DyScO3, YAlO3, and LaAlO3 can be of\npotential use for a Raman based thin film research. At the same time TiO2\n(rutile), NdGaO3, SrLaAlO4, and SrTiO3 single crystals exhibit multiple phonon\nmodes accompanied by strong Raman background that substantially hinder the\nRaman based thin film experiments.",
        "positive": "Enhancement of Coulomb interactions in semiconductor nanostructures by\n  dielectric confinement: We present a theoretical analysis of the effect of dielectric confinement on\nthe Coulomb interaction in dielectrically modulated quantum structures. We\ndiscuss the implications of the strong enhancement of the electron-hole and\nelectron-electron coupling for two specific examples: (i) GaAs-based quantum\nwires with remote oxide barriers, where combined quantum and dielectric\nconfinements are predicted to lead to room temperature exciton binding, and\n(ii) semiconductor quantum dots in colloidal environments, where the many-body\nground states and the addition spectra are predicted to be drastically altered\nby the dielectric environment."
    },
    {
        "anchor": "Multiphase Magnetic Systems: Measurement and Simulation: Multiphase magnetic systems are common in nature and are increasingly being\nrecognized in technical applications. One characterization method which has\nshown great promise for determining separate and collective effects of\nmultiphase magnetic systems is first order reversal curves (FORCs). Several\nexamples are given of FORC patterns which provide distinguishing evidence of\nmultiple phases. In parallel, a visualization method for understanding\nmultiphase magnetic interaction is given, which allocates Preisach magnetic\nelements as an input 'Preisach hysteron distribution pattern' (PHDP) to enable\nsimulation of different 'wasp-waisted' magnetic behaviors. These simulated\nsystems allow reproduction of different major hysteresis loop, FORC pattern,\nand switching field distributions of real systems and parameterized theoretical\nsystems. The experimental FORC measurements and FORC diagrams of four\ncommercially obtained magnetic materials, particularly those sold as\nnanopowders, shows that these materials are often not phase pure. They exhibit\ncomplex hysteresis behaviors that are not predictable based on relative phase\nfraction obtained by characterization methods such as diffraction. These\nmultiphase materials, consisting of various fractions of BaFe12O19,\nepsilon-Fe2O3, and gamma-Fe2O3, are discussed.",
        "positive": "Hole spin polarization in GaAlAs:Mn structures: A self-consistent calculation of the electronic properties of GaAlAs:Mn\nmagnetic semiconductor quantum well structures is performed including the\nHartree term and the sp-d exchange interaction with the Mn magnetic moments.\nThe spin polarization density is obtained for several structure configurations.\nAvailable experimental results are compared with theory."
    },
    {
        "anchor": "Functionalization of Single Layer MoS$_2$ Honeycomb Structures: Based on the first-principles plane wave calculations, we studied the\nfunctionalization of the two-dimensional single layer MoS$_2$ structure via\nadatom adsorption and vacancy defect creation. Minimum energy adsorption sites\nare determined for sixteen different adatoms, each gives rise to diverse\nproperties. Bare, single layer MoS$_2$, which is normally a nonmagnetic, direct\nband gap semiconductor, attains a net magnetic moment upon adsorption of\nspecific transition metal atoms, as well as silicon and germanium atoms. The\nlocalized donor and acceptor states in the band gap expand the utilization of\nMoS$_2$ in nanoelectronics and spintronics. Specific adatoms, like C and O,\nattain significant excess charge upon adsorption to single layer MoS$_{2}$\nwhich may be useful for its tribological applications. Each MoS$_{2}$-triple\nvacancy created in a single layer MoS$_{2}$ gives rise to a net magnetic\nmoment, while other vacancy defects related with Mo and S atoms do not\ninfluence the nonmagnetic ground state. Present results are also relevant for\nthe surface of graphitic MoS$_2$.",
        "positive": "Online Search Tool for Graphical Patterns in Electronic Band Structures: We present an online graphical pattern search tool for electronic band\nstructure data contained within the Organic Materials Database (OMDB) available\nat https://omdb.diracmaterials.org/search/pattern. The tool is capable of\nfinding user-specified graphical patterns in the collection of thousands of\nband structures from high-throughput ab initio calculations in the online\nregime. Using this tool, it only takes a few seconds to find an arbitrary\ngraphical pattern within the ten electronic bands near the Fermi level for\n26,739 organic crystals. The tool can be used to find realizations of\nfunctional materials characterized by a specific pattern in their electronic\nstructure, for example, Dirac materials, characterized by a linear crossing of\nbands; topological insulators, characterized by a \"Mexican hat\" pattern or an\neffectively free electron gas, characterized by a parabolic dispersion. The\nsource code of the developed tool is freely available at\nhttps://github.com/OrganicMaterialsDatabase/EBS-search and can be transferred\nto any other electronic band structure database. The approach allows for an\nautomatic online analysis of a large collection of band structures where the\namount of data makes its manual inspection impracticable."
    },
    {
        "anchor": "Electronic Structures of N-doped Graphene with Native Point Defects: Nitrogen doping in graphene has important implications in graphene-based\ndevices and catalysts. We have performed the density functional theory\ncalculations to study the electronic structures of N-doped graphene with\nvacancies and Stone-Wales defect. Our results show that monovacancies in\ngraphene act as hole dopants and that two substitutional N dopants are needed\nto compensate for the hole introduced by a monovacancy. On the other hand,\ndivacancy does not produce any free carriers. Interestingly, a single N dopant\nat divacancy acts as an acceptor rather than a donor. The interference between\nnative point defect and N dopant strongly modifies the role of N doping\nregarding the free carrier production in the bulk pi bands. For some of the\ndefects and N dopant-defect complexes, localized defect pi states are partially\noccupied. Discussion on the possibility of spin polarization in such cases is\ngiven. We also present qualitative arguments on the electronic structures based\non the local bond picture. We have analyzed the 1s-related x-ray photoemission\nand adsorption spectroscopy spectra of N dopants at vacancies and Stone-Wales\ndefect in connection with the experimental ones. We also discuss characteristic\nscanning tunneling microscope (STM) images originating from the electronic and\nstructural modifications by the N dopant-defect complexes. STM imaging for\nsmall negative bias voltage will provide important information about possible\nactive sites for oxygen reduction reaction.",
        "positive": "Electronic properties of silica nanowires: Thin nanowires of silicon oxide were studied by pseudopotential density\nfunctional electronic structure calculations using the generalized gradient\napproximation. Infinite linear and zigzag Si-O chains were investigated. A wire\ncomposed of three-dimensional periodically repeated Si4O8 units was also\noptimized, but this structure was found to be of limited stability. The\ngeometry, electronic structure, and Hirshfeld charges of these silicon oxide\nnanowires were computed. The results show that the Si-O chain is metallic,\nwhereas the zigzag chain and the Si4O8 nanowire are insulators."
    },
    {
        "anchor": "Valence electron concentration- and N vacancy-induced elasticity in\n  cubic early transition metal nitrides: Motivated by frequently reported deviations from stoichiometry in cubic\ntransition metal nitride (TMNx) thin films, the effect of N-vacancy\nconcentration on the elastic properties of cubic TiNx, ZrNx, VNx, NbNx, and\nMoNx (0.72<x<1.00) is systematically studied by density functional theory (DFT)\ncalculations. The predictions are validated experimentally for VNx\n(0.77<x<0.97). The DFT results indicate that the elastic behavior of the TMNx\ndepends on both the N-vacancy concentration and the valence electron\nconcentration (VEC) of the transition metal: While TiNx and ZrNx exhibit\nvacancy-induced reductions in elastic modulus, VNx and NbNx show an increase.\nThese trends can be rationalized by considering vacancy-induced changes in\nelastic anisotropy and bonding. While introduction of N-vacancies in TiNx\nresults in a significant reduction of elastic modulus along all directions and\na lower average bond strength of Ti-N, the vacancy-induced reduction in [001]\ndirection of VNx is overcompensated by the higher stiffness along [011] and\n[111] directions, resulting in a higher average bond strength of V-N. To\nvalidate the predicted vacancy-induced changes in elasticity experimentally,\nclose-to-single-crystal VNx (0.77<x<0.97) are grown on MgO(001) substrates. As\nthe N-content is reduced, the relaxed lattice parameter a0, as probed by X-ray\ndiffraction, decreases from 4.128 A to 4.096 A. This reduction in lattice\nparameter is accompanied by an anomalous 11% increase in elastic modulus, as\ndetermined by nanoindentation. As the experimental data agree with the\npredictions, the elasticity enhancement in VNx upon N-vacancy formation can be\nunderstood based on the concomitant changes in elastic anisotropy and bonding.",
        "positive": "Angular dependence of the electrically driven and detected ferromagnetic\n  resonance in Ni$_{36}$Fe$_{64}$ wires: We study the angular dependence of ferromagnetic resonance (FMR) in\nNi$_{36}$Fe$_{64}$ wires using both traditional microwave-absorption and\nelectrical-detection techniques. In our experiments we apply a static magnetic\nfield at an angle $\\theta$ with respect to the wire, while the microwave\ncurrent, which is responsible for driving FMR, is always flowing along the\nwire. For different $\\theta$s we find a very similar behavior for both\nmicrowave-absorption and electrically-detected FMR -- the resonance magnetic\nfield follows a simple \"$1/\\cos(\\theta)$\" dependence. This simple behavior\nhighlights the importance of the relative orientation between the driving\ncurrent and magnetic field. We also investigated the dependence of the\nelectrically detected FMR on dc and rf (microwave) current magnitudes. As\nexpected, the resonance signal increases linearly with both the applied dc\ncurrent and the microwave power."
    },
    {
        "anchor": "Manipulation of magnetic anisotropy of 2D magnetized graphene by\n  ferroelectric In$_2$Se$_3$: The capacity to externally manipulate magnetic properties is highly desired\nfrom both fundamental and technological perspectives, particularly in the\ndevelopment of magnetoelectronics and spintronics devices. Here, using\nfirst-principles calculations, we have demonstrated the ability of controlling\nthe magnetism of magnetized graphene monolayers by interfacing them with a\ntwo-dimensional ferroelectric material. When the 3$d$ transition metal (TM) is\nadsorbed on the graphene monolayer, its magnetization easy axis can be flipped\nfrom in-plane to out-of-plane by the ferroelectric polarization reversal of\nIn$_2$Se$_3$, and the magnetocrystalline anisotropy energy (MAE) can be high to\n-0.692 meV/atom when adopting the Fe atom at bridge site with downward\npolarization. This may be a universal method since the 3$d$ TM-adsorbed\ngraphene has a very small MAE, which can be easily manipulated by the\nferroelectric polarization. As a result, the inherent mechanism is analyzed by\nsecond variation method.",
        "positive": "Formation of lead halide perovskite precursors in solution: Insight from\n  electronic-structure theory: Understanding the formation of lead halide (LH) perovskite solution\nprecursors is crucial to gain insight into the evolution of these materials to\nthin films for solar cells. Using density-functional theory in conjunction with\nthe polarizable continuum model, we investigate 18 complexes with chemical\nformula PbX$_2$M$_4$, where X = Cl, Br, I and M are common solvent molecules.\nThrough the analysis of structural properties, binding energies, and charge\ndistributions, we clarify the role of halogen species and solvent molecules in\nthe formation of LH perovskite precursors. We find that interatomic distances\nare critically affected by the halogen species, while the energetic stability\nis driven by the solvent coordination to the backbones. Regardless of the\nsolvent, lead iodide complexes are more strongly bound than the others. Based\non the charge distribution analysis, we find that all solvent molecules bind\ncovalently with the LH backbones and that Pb-I and Pb-Br bonds lose ionicity in\nsolution. Our results contribute to clarify the physical properties of LH\nperovskite solution precursors and offer a valuable starting point for further\ninvestigations on their crystalline intermediates."
    },
    {
        "anchor": "Machine-learning accelerated geometry optimization in molecular\n  simulation: Geometry optimization is an important part of both computational materials\nand surface science because it is the path to finding ground state atomic\nstructures and reaction pathways. These properties are used in the estimation\nof thermodynamic and kinetic properties of molecular and crystal structures.\nThis process is slow at the quantum level of theory because it involves an\niterative calculation of forces using quantum chemical codes such as density\nfunctional theory (DFT), which are computationally expensive, and which limit\nthe speed of the optimization algorithms. It would be highly advantageous to\naccelerate this process because then one could either do the same amount of\nwork in less time, or more work in the same time. In this work, we provide a\nneural network (NN) ensemble based active learning method to accelerate the\nlocal geometry optimization for multiple configurations simultaneously. We\nillustrate the acceleration on several case studies including bare metal\nsurfaces, surfaces with adsorbates, and nudged elastic band (NEB) for two\nreactions. In all cases the accelerated method requires fewer DFT calculations\nthan the standard method. In addition, we provide an ASE-optimizer Python\npackage to make the usage of the NN ensemble active learning for geometry\noptimization easier.",
        "positive": "First-Principles Study of Strain Effect on Thermoelectric Properties of\n  LaP and LaAs: Rare-earth monopnictides have attracted much attention due to their unusual\nelectronic and topological properties for potential device applications. Here,\nwe study rock-salt structured lanthanum monopnictides LaX (X = P, As) by\ndensity functional theory (DFT) simulations. We show systematically that a\nmeta-GGA functional combined with scissor correction can efficiently and\naccurately compute electronic structures on a fine DFT $k$-grid, which is\nnecessary for converging thermoelectric calculations. We also show that strain\nengineering can effectively improve thermoelectric performance. Under the\noptimal condition of 2% tensile strain and carrier concentration\n$n=3\\times10^{20}~\\textrm{cm}^{-3}$, LaP at temperature 1200 K can achieve a\nfigure of merit $ZT$ value $>2$, which is enhanced by 90% compared to the\nunstrained value. With carrier doping and strain engineering, lanthanum\nmonopnictides thereby could be promising high-temperature thermoelectric\nmaterials."
    },
    {
        "anchor": "Production and application of metal-based nanoparticles: A number of metal-based nanopowders such kinds as Fe, Co, Fe/Co alloy, Fe/C,\nFe/organic shell were successfully produced by aerosol synthesis method. The\nmechanism of nanoparticles formation and the influence of experimental\nparameters on shape, size distribution, structure, chemical and phase\ncomposition of oxide-, carbon-, or organic- coated nanoparticles were\nevaluated. The sizes of particles can be varied from 6-100 nm with narrow size\ndistribution. The several application fields of synthesized nanoparticles have\nbeen studied.",
        "positive": "Microstructure-based fatigue life model of metallic alloys with bilinear\n  Coffin-Manson behavior: A microstructure-based model is presented to predict the fatigue life of\npolycrystalline metallic alloys which present a bilinear Coffin-Manson\nrelationship. The model is based in the determination of the maximum value of a\nfatigue indicator parameter obtained from the plastic energy dissipated by\ncycle in the microstructure. The fatigue indicator parameter was obtained by\nmeans of the computational homogenization of a representative volume element of\nthe microstructure using a crystal-plasticity finite element model. The\nmicrostructure-based model was applied to predict the low cyclic fatigue\nbehavior of IN718 at 400$^\\circ$C which exhibits a bilinear Coffin-Manson\nrelationship under the assumption that this behavior is triggered by a\ntransition from highly localized plasticity at low cyclic strain amplitudes to\nmore homogeneous deformation at high cyclic strain amplitudes. The model\npredictions were in very good agreement with the experimental results for a\nwide range of cyclic strain amplitudes and two strain ratios ($R_\\epsilon$ = 0\nand -1) and corroborated the initial hypothesis. Moreover, they provided a\nmicromechanical explanation for the influence of the strain ratio on the\nfatigue life at low cyclic strain amplitudes."
    },
    {
        "anchor": "Radiation-resistant aluminium alloy for space missions in the extreme\n  environment of the solar system: Future human-based exploration of our solar system requires the invention of\nmaterials that can resist harsh environments. Age-hardenable aluminium alloys\nwould be attractive candidates for structural components in long-distance\nspacecrafts, but their radiation resistance to solar energetic particles is\ninsufficient. Common hardening phases dissolve and displacement damage occurs\nin the alloy matrix, which strongly degrades properties. Here we present an\nalloy where hardening is achieved by T-phase, featuring a giant unit cell and\nhighly-negative enthalpy of formation. The phase shows record radiation\nsurvivability and can stabilize an ultrafine-grained structure upon temperature\nand radiation in the alloy, therby successfully preventing displacement damage\nto occur. Such concept can be considered ideal for the next-generation space\nmaterials and the design of radiation resistant alloy.",
        "positive": "The order-disorder character of the (3x3) to (sqrt3 x sqrt3)R30&#176;\n  phase transition of Sn on Ge(111): Growing attention has been drawn in the past years to the \\alpha-phase\n  (1/3 monolayer) of Sn on Ge(111), which undergoes a transition from the low\ntemperature (3x3) phase to the room temperature (\\sqrt3 x \\sqrt3)R30&#176; one.\nOn the basis of scanning tunnelling microscopy experiments, this transition was\nclaimed to be the manifestation of a surface charge density wave (SCDW), i.e. a\nperiodic redistribution of charge, possibly accompanied by a periodic lattice\ndistortion, which determines a change of the surface symmetry.\n  Recent He diffraction studies of the (3x3) long range order have shown the\ntransition to be of the order-disorder type with a critical temperature Tc=220\nK and belonging to the 3-state Potts' universality class. These findings\nclearly exclude an SCDW driven mechanism at 220 K, but they cannot exclude the\noccurence of a displacive transition at higher temperature. Here we present\nphotoelectron diffraction data taken at 300 K and photoemission data taken up\nto 500 K (which is the maximum temperature where the (\\sqrt3 x \\sqrt3)R30&#176;\nis stable) . From our analysis it is shown that the atomic structure of the Sn\noverlayer does not change throughout the transition up to 500 K. As a\nconsequence the displacive hypothesis must be discarded in favour of a genuine\norder-disorder model."
    },
    {
        "anchor": "Anomalous transverse acoustic phonon broadening in the relaxor\n  ferroelectric Pb(Mg_1/3Nb_2/3)O_3: The intrinsic linewidth $\\Gamma_{TA}$ of the transverse acoustic (TA) phonon\nobserved in the relaxor ferroelectric compound\nPb(Mg$_{1/3}$Nb$_{2/3})_{0.8}$Ti$_{0.2}$O$_3$ (PMN-20%PT) begins to broaden\nwith decreasing temperature around 650 K, nearly 300 K above the ferroelectric\ntransition temperature $T_c$ ($\\sim 360$ K). We speculate that this anomalous\nbehavior is directly related to the condensation of polarized, nanometer-sized,\nregions at the Burns temperature $T_d$. We also observe the ``waterfall''\nanomaly previously seen in pure PMN, in which the transverse optic (TO) branch\nappears to drop precipitously into the TA branch at a finite momentum transfer\n$q_{wf} \\sim 0.15$ \\AA$^{-1}$. The waterfall feature is seen even at\ntemperatures above $T_d$. This latter result suggests that the PNR exist as\ndynamic entities above $T_d$.",
        "positive": "Structural and dielectric properties of glasses in the system\n  TeO2-CaCu3Ti4O12: The glasses in the system (100-x)TeO2-xCaCu3Ti4O12, (x=0.25 to 3 mol %) were\nfabricated. The color varied from olive green to brown as the CaCu3Ti4O12\n(CCTO) content increased in TeO2 matrix. The X-ray powder diffraction and\ndifferential scanning calorimetric analyses that were carried out on the\nas-quenched samples confirmed their amorphous and glassy nature respectively.\nThe dielectric constant and loss in the 100 Hz-1MHz frequency range were\nmonitored as a function of temperature (50-400oC). The dielectric constant and\nthe loss (D) increased as the CCTO content increased in TeO2 at all the\nfrequencies and temperatures under investigation. Further, the effective\ndielectric constant and D were found to be frequency independent in the\n50-200oC temperature range. The value obtained for the loss at 1MHz was 0.0019\nwhich was typical of low loss materials, and exhibited near constant loss (NCL)\nin the 100Hz-1MHz frequency range. The electrical relaxation was rationalized\nusing the electric modulus formalism. These glasses may be of considerable\ninterest as substrates for high frequency circuit elements in conventional\nsemiconductor industries owing to their high thermal stability."
    },
    {
        "anchor": "Angular dependent resonant photoemission processes at the 2p thresholds\n  in nickel metal: Angle-resolved valence-band resonant photoemission of nickel metal has been\nmeasured close to the 2p core-level thresholds with synchrotron radiation. The\nwell-known 6-eV correlation satellite has an intensity enhancement of about two\norders of magnitude at resonance. The angular dependence of the photoemission\nintensity has been studied as function of photon energy and provides\nunambiguous evidence for interference effects all the way up to the resonance\nmaximum. The observation of different angular asymmetries, {\\beta}, for the\nvalence band and the satellite is discussed in connection to the origin of the\nresonant photoemission process and the character of the satellite.",
        "positive": "Monolayer phosphorene under time-dependent magnetic field: We obtain the exact wave function of a monolayer phosphorene under a low-\nintensity time-dependent magnetic field using the dynamical invariant method.\nWe calculate the quantum-mechanical energy expectation value and the transition\nprobability for a constant and an oscillatory magnetic field. For the former we\nobserve that the Landau level energy varies linearly with the quantum numbers n\nand m and the magnetic field intensity B_0. No transition takes place. For the\nlatter, we observe that the energy oscillates in time, increasing linearly with\nthe Landau level n and m and nonlinearly with the magnetic field. The (k,l) to\n(n,m) transitions take place only for l=m. We investigate the (0,0) to (n,0)\nand (1,l) and (2,l) probability transitions."
    },
    {
        "anchor": "Durable, ultrathin, and antifouling polymer brush coating for efficient\n  condensation heat transfer: Heat exchangers are made of metals because of their high heat conductivity\nand mechanical stability. Metal surfaces are inherently hydrophilic, leading to\ninefficient filmwise condensation. It is still a challenge to coat these metal\nsurfaces with a durable, robust and thin hydrophobic layer, which is required\nfor efficient dropwise condensation. Here, we report the non-structured and\nultrathin (~6 nm) polydimethylsiloxane (PDMS) brushes on copper that sustain\nhigh-performing dropwise condensation in high supersaturation. Due to the\nflexible hydrophobic siloxane polymer chains, the coating has low resistance to\ndrop sliding and excellent chemical stability. The PDMS brushes can sustain\ndropwise condensation for up to ~8 h during exposure to 111 {\\deg}C saturated\nsteam flowing at 3 m/s, with a 5-7 times higher heat transfer coefficient\ncompared to filmwise condensation. The surface is self-cleaning and can reduce\nbacterial attachment by 99%. This low-cost, facile, fluorine-free, and scalable\nmethod is suitable for a great variety of condensation heat transfer\napplications.",
        "positive": "Multiple high-pressure phase transitions in BiFeO3: We investigate the high-pressure phase transitions in BiFeO3 by single\ncrystal and powder x-ray diffraction, as well as single crystal Raman\nspectroscopy. Six phase transitions are reported in the 0-60 GPa range. At low\npressures, up to 15 GPa, 4 transitions are evidenced at 4, 5, 7 and 11 GPa. In\nthis range, the crystals display large unit cells and complex domain\nstructures, which suggests a competition between complex tilt systems and\npossibly off-center cation displacements. The non polar Pnma phase remains\nstable over a large pressure range between 11 and 38 GPa, where the distortion\n(tilt angles) changes only little with pressure. The two high-pressure phase\ntransitions at 38 and 48 GPa are marked by the occurence of larger unit cells\nand an increase of the distorsion away from the cubic parent perovskite cell.\nWe find no evidence for a cubic phase at high pressure, nor indications that\nthe structure tends to become cubic. The previously reported insulator-to-metal\ntransition at 50 GPa appears to be symmetry breaking."
    },
    {
        "anchor": "Momentum-space imaging of ultra-thin electron liquids in delta-doped\n  silicon: Two-dimensional dopant layers ($\\delta$-layers) in semiconductors provide the\nhigh-mobility electron liquids (2DELs) needed for nanoscale quantum-electronic\ndevices. Key parameters such as carrier densities, effective masses, and\nconfinement thicknesses for 2DELs have traditionally been extracted from\nquantum magnetotransport. In principle, the parameters are immediately readable\nfrom the one-electron spectral function that can be measured by angle-resolved\nphotoemission spectroscopy (ARPES). Here, buried 2DEL $\\delta$-layers in\nsilicon are measured with soft X-ray (SX) ARPES to obtain detailed information\nabout their filled conduction bands and extract device-relevant properties.\nThis study takes advantage of the larger probing depth and photon energy range\nof SX-ARPES relative to vacuum ultraviolet (VUV) ARPES to accurately measure\nthe $\\delta$-layer electronic confinement. The measurements are made on\nambient-exposed samples and yield extremely thin ($\\approx 1$ $nm$) and dense\n($\\approx$ $10^{14}$ $cm^2$) 2DELs. Critically, this method is used to show\nthat $\\delta$-layers of arsenic exhibit better electronic confinement than\n$\\delta$-layers of phosphorus fabricated under identical conditions.",
        "positive": "Impersonating a Superconductor: High-Pressure BaCoO$_3$, an Insulating\n  Ferromagnet: We report the high-pressure synthesis (6 GPa, 1200 $^{\\circ}$C) and ambient\npressure characterization of hexagonal HP-BaCoO$_3$. The material (with the 2H\ncrystal structure) has a short intrachain Co-Co distance of about 2.07\n$\\text{\\r{A}}$. Our magnetization investigation revealed robust diamagnetic\nbehavior below approximately 130 K when exposed to weak applied magnetic fields\n(10 Oe) and a distinct half-levitation phenomenon below that temperature, such\nas is often observed for superconductors. Its field-dependent magnetization\nprofile, however, unveils the characteristics of ferromagnetism, marked by a\nsubstantial magnetic retentivity of 0.22(1) ${\\mu}_B$/Co at a temperature of 2\nK. Electrical resistivity measurements indicate that HP-BaCoO$_3$ is a\nferromagnetic insulator, not a superconductor."
    },
    {
        "anchor": "Giant semiclassical magnetoresistance in high mobility TaAs2 semimetal: We report the observation of colossal positive magnetoresistance (MR) in\nsingle crystalline, high mobility TaAs2 semimetal. The excellent fit of MR by a\nsingle quadratic function of the magnetic field B over a wide temperature range\n(T = 2-300 K) suggests the semiclassical nature of the MR. The measurements of\nHall effect and Shubnikov-de Haas oscillations, as well as band structure\ncalculations suggest that the giant MR originates from the nearly perfectly\ncompensated electrons and holes in TaAs2. The quadratic MR can even exceed\n1,200,000% at B = 9 T and T = 2 K, which is one of the largest values among\nthose of all known semi-metallic compounds including the very recently\ndiscovered WTe2 and NbSb2. The giant positive magnetoresistance in TaAs2, which\nnot only has a fundamentally different origin from the negative colossal MR\nobserved in magnetic systems, but also provides a nice complemental system that\nwill be beneficial for applications in magnetoelectronic devices",
        "positive": "Machine learning of microscopic ingredients for graphene oxide/cellulose\n  interaction: Understanding the role of microscopic attributes in nanocomposites allows for\na controlled and, therefore, acceleration in experimental system designs. In\nthis work, we extracted the relevant parameters controlling the graphene oxide\nbinding strength to cellulose by combining first-principles calculations and\nmachine learning algorithms. We were able to classify the systems among two\nclasses with higher and lower binding energies, which are well defined based on\nthe isolated graphene oxide features. By a theoretical X-ray photoelectron\nspectroscopy analysis, we show the extraction of these relevant features.\nAdditionally, we demonstrate the possibilities of a refined control within a\nmachine learning regression between the binding energy values and the system's\ncharacteristics. Our work presents a guiding map to the control graphene\noxide/cellulose interaction."
    },
    {
        "anchor": "Influence of ferroelastic domain walls on thermal conductivity: Enabling on-demand control of heat flow is key for the development of\nnext-generation electronic devices, solid-state heat pumps, and thermal logic.\nHowever, precise and agile tuning of the relevant microscopic material\nparameters for adjusting thermal conductivities remains elusive. Here, we study\nseveral single crystals of lanthanum aluminate (LaAlO$_{3}$) with different\ndomain structures and show that ferroelastic domain walls behave as boundaries\nthat act like efficient controllers to govern thermal conductivity. At low\ntemperature (3 K), we demonstrate a fivefold reduction in thermal conductivity\ninduced by domain walls orthogonal to the heat flow and a twofold reduction\nwhen they are parallel to the heat flow. Atomistic calculations fully support\nthis experimental observation. By breaking down phonon scattering mechanisms,\nwe also analyze the temperature dependence of the thermal conductivity to\nderive a quantitative relation between thermal conductivity variations and\ndomain wall organization and density.",
        "positive": "Mobile Kink Solitons in a Van der Waals Charge-Density-Wave Layer: Kinks, point-like geometrical defects along dislocations, domain walls, and\nDNA, are stable and mobile, as solutions of a sine-Gordon wave equation. While\nthey are widely investigated for crystal deformations and domain wall motions,\nelectronic properties of individual kinks have received little attention. In\nthis work, electronically and topologically distinct kinks are discovered along\nelectronic domain walls in a correlated van der Waals insulator of\n1$T$-TaS$_2$. Mobile kinks and antikinks are identified as trapped by pinning\ndefects and imaged in scanning tunneling microscopy. Their atomic structures\nand in-gap electronic states are unveiled, which are mapped approximately into\nSu-Schrieffer-Heeger solitons. The twelve-fold degeneracy of the domain walls\nin the present system guarantees an extraordinarily large number of distinct\nkinks and antikinks to emerge. Such large degeneracy together with the robust\ngeometrical nature may be useful for handling multilevel information in van der\nWaals materials architectures."
    },
    {
        "anchor": "A discrete nonlinear mass transfer equation with applications in\n  solid-state sintering of ceramic materials: The evolution of grain structures in materials is a complex and multiscale\nprocess that determines the material's final properties. Understanding the\ndynamics of grain growth is a key factor for controlling this process. We\npropose a phenomenological approach, based on a nonlinear, discrete mass\ntransfer equation for the evolution of an arbitrary initial grain size\ndistribution. Transition rates for mass transfer across grains are assumed to\nfollow the Arrhenius law, but the activation energy depends on the degree of\namorphization of each grain. We argue that the magnitude of the activation\nenergy controls the final (sintered) grain size distribution, and we verify\nthis prediction by numerical simulation of mass transfer in a one-dimensional\ngrain aggregate.",
        "positive": "Optical imaging of strain-mediated phase coexistence during\n  electrothermal switching in a Mott insulator: Resistive-switching -- the current-/voltage-induced electrical resistance\nchange -- is at the core of memristive devices, which play an essential role in\nthe emerging field of neuromorphic computing. This study is about resistive\nswitching in a Mott-insulator, which undergoes a thermally driven\nmetal-to-insulator transition. Two distinct switching mechanisms were reported\nfor such a system: electric-field-driven resistive switching and electrothermal\nresistive switching. The latter results from an instability caused by Joule\nheating. Here, we present the visualization of the reversible resistive\nswitching in a planar V$_2$O$_3$ thin-film device using high-resolution\nwide-field microscopy in combination with electric transport measurements. We\ninvestigate the interaction of the electrothermal instability with the\nstrain-induced spontaneous phase-separation in the V$_2$O$_3$ thin film at the\nMott-transition. The photomicrographs show the formation of a narrow metallic\nfilament with a minimum width $\\lesssim$ 500\\,nm. Although the filament\nformation and the overall shape of the current-voltage characteristics (IVCs)\nare typical of an electrothermal breakdown, we also observe atypical effects\nlike oblique filaments, filament splitting, and hysteretic IVCs with\nsawtooth-like jumps at high currents in the low-resistance regime. We were able\nto reproduce the experimental results in a numerical model based on a\ntwo-dimensional resistor network. This model demonstrates that resistive\nswitching, in this case, is indeed electrothermal and that the intrinsic\nheterogeneity is responsible for the atypical effects. This heterogeneity is\nstrongly influenced by strain, thereby establishing a link between switching\ndynamics and structural properties."
    },
    {
        "anchor": "Mechanical properties of ultra-hard nanocrystalline cubic boron nitride: Nanostructure and mechanical properties of bulk nanocristalline cubic boron\nnitride have been studied by transmission electron microscopy, and micro- and\nnanoindentation. The obtained data on hardness, elastic properties and fracture\ntoughness clearly indicate that nano-cBN belongs to a family of advanced\nultra-hard materials.",
        "positive": "Comment on '[N(CH3)3H]2ZnCl4: Ferroelectric properties and\n  characterization of phase transitions by Raman spectroscopy': The authors of paper commented claim that trimethylammonium\ntetrachlorozincate crystal shows at 282 K the ferroelectric-paraelectric phase\ntransition. But no ferroelectric hysteresis loop was observed below this\ntemperature. Moreover, in the low-temperature phase the ferroelectric domain\nwalls should exist giving dielectric relaxation in a low frequency electric\nfield. The authors conclude that the phase transition is of the second order.\nThis conclusion is contrary to the DSC data where the phase transition has a\nstrong first order character. In the whole measured temperature range the\ndielectric loss is 100 times higher than the real part of dielectric constant."
    },
    {
        "anchor": "Devil's staircase transition of the electronic structures in CeSb: Solids with competing interactions often undergo complex phase transitions\nwith a variety of long-periodic modulations. Among such transition, devil's\nstaircase is the most complex phenomenon, and for it, CeSb is the most famous\nmaterial, where a number of the distinct phases with long-periodic\nmagnetostructures sequentially appear below the Neel temperature. An evolution\nof the low-energy electronic structure going through the devil's staircase is\nof special interest, which has, however, been elusive so far despite the\n40-years of intense researches. Here we use bulk-sensitive angle-resolved\nphotoemission spectroscopy and reveal the devil's staircase transition of the\nelectronic structures. The magnetic reconstruction dramatically alters the band\ndispersions at each transition. We moreover find that the well-defined band\npicture largely collapses around the Fermi energy under the long-periodic\nmodulation of the transitional phase, while it recovers at the transition into\nthe lowest-temperature ground state. Our data provide the first direct evidence\nfor a significant reorganization of the electronic structures and spectral\nfunctions occurring during the devil's staircase.",
        "positive": "Zone-folded longnitude acoustic phonons driving self-trapped state\n  emission in colloidal CdSe nanoplate superlattice: Colloidal cadmium chalcogenide nanoplates are two-dimensional semiconductors\nthat have shown great application prospect for light-emitting technologies.\nSelf-trapped state (STS), a special localized state originated from strong\nelectron-phonon coupling (EPC), has great potential in one-step white light\nluminance owing to its broadband emission linewidth. However, achieving STS in\ncadmium chalcogenide nanocrystals is extremely challenging due to their\nintrinic weak EPC nature. By building hybrid superlattice (SL) structures via\nself-assembly of colloidal CdSe nanoplates (NPLs), we demonstrated an emergence\nof zone-folded longnitude acoustic phonons (ZFLAP) differ from monodispersed\nNPLs, and observed a broadband STS emission in spectra range of 450-600 nm.\nThrough femtosecond transient absorption and impulsive vibrational\nspectroscopy, we revealed that STS is generated in time scale of ~500 fs and is\ndriven by strong coupling of excitons and ZFLAPs with Huang-Rhys parameter as\nlarge as ~22.7. Our findings provide a new avenue for generating and\nmanipulating STS emission by artificially designing and building hybrid\nperiodic structures superior to single material optimization."
    },
    {
        "anchor": "High Performance Calculation of Magnetic Properties and Simulation of\n  Nonequilibrium Phenomena in nanofilms: Images of surface topography of ultrathin magnetic films have been used for\nMonte Carlo simulations in the framework of the ferromagnetic Ising model to\nstudy the hysteresis and thermal properties of nanomaterials. For high\nperformance calculations was used super-scalable parallel algorithm for the\nfinding of the equilibrium configuration. The changing of a distribution of\nspins on the surface during the reversal of the magnetization and the dynamics\nof nanodomain structure of thin magnetic films under the influence of changing\nexternal magnetic field was investigated.",
        "positive": "Suppressing dynamical diffraction artefacts in differential phase\n  contrast scanning transmission electron microscopy of long-range\n  electromagnetic fields via precession: In differential phase contrast scanning transmission electron microscopy\n(DPC-STEM), variability in dynamical diffraction resulting from changes in\nsample thickness and local crystal orientation (due to sample bending) can\nproduce contrast comparable to that arising from the long-range electromagnetic\nfields probed by this technique. Through simulation we explore the scale of\nthese dynamical diffraction artefacts and introduce a metric for the magnitude\nof their confounding contribution to the contrast. We show that precession over\nan angular range of a few milliradian can suppress this confounding contrast by\none-to-two orders of magnitude. Our exploration centres around a case study of\nGaAs near the [011] zone-axis orientation using a probe-forming aperture\nsemiangle on the order of 0.1 mrad at 300 keV, but the trends found and\nmethodology used are expected to apply more generally."
    },
    {
        "anchor": "Impact of Size and Thermal Gradient on Supercooling of Phase Change\n  Materials for Thermal Energy Storage: Phase change material based thermal energy storage has many current and\npotential applications in the heating and cooling of buildings, battery and\nelectronics thermal management, thermal textiles, and dry cooling of power\nplants. However, connecting lab scale thermal data obtained on DSC to the\nperformance of large-scale practical systems has been a major challenge\nprimarily due to the dependence of supercooling on the size and temperature\ngradient of the system. In this work we show how a phase change material's\nsupercooling behavior can be characterized experimentally using common lab\nscale thermal analysis techniques. We then develop a statistics based\ntheoretical model that uses the lab scale data on small samples to\nquantitatively predict the supercooling performance for a general thermal\nenergy storage application of any size with temperature gradients. Finally, we\nvalidate the modeling methodology by comparing to experimental results for\nsolid-solid phase change in neopentyl glycol, which shows how the model\nsuccessfully predicts the changes in supercooling temperature across a large\nrange of cooling rates (2 orders of magnitude) and volumes (3 orders of\nmagnitude). By accounting for thermal gradients, the model avoids ~2x error\nincurred by lumped approximations.",
        "positive": "Raman Tensor Calculation for Magnesium Phthalocyanine: We present ab-initio density functional (DFT) calculations of the vibrational\nspectra of neutral Magnesium phthalocyanine (MgPc) molecule and of its Raman\nscattering intensities."
    },
    {
        "anchor": "Multiaxial Kitagawa analysis of A356-T6: Experimental Kitagawa analysis has been performed on A356-T6 containing\nnatural and artificial defects. Results are obtained with a load ratio of R =\n-1 for three different loadings: tension, torsion and combined tension-torsion.\nThe critical defect size determined is 400 \\pm 100 \\mum in A356-T6 under\nmultiaxial loading. Below this value, the microstructure governs the endurance\nlimit mainly through Secondary Dendrite Arm Spacing (SDAS). Four theoretical\napproaches are used to simulate the endurance limit characterized by a Kitagawa\nrelationship are compared: Murakami relationships [Y Murakami, Metal Fatigue:\nEffects of Small Defects and Nonmetallic Inclusions, Elsevier, 2002.],\ndefect-crack equivalency via Linear Elastic Fracture Mechanics (LEFM), the\nCritical Distance Method (CDM) proposed by Susmel and Taylor [L. Susmel, D.\nTaylor. Eng. Fract. Mech. 75 (2008) 15.] and the gradient approach proposed by\nNadot [Y. Nadot, T. ~Billaudeau. Eng. Fract. Mech. 73 (2006) 1.]. It is shown\nthat the CDM and gradient methods are accurate; however fatigue data for three\nloading conditions is necessary to allow accurate identification of an\nendurance limit.",
        "positive": "First-Principles Prediction of the Softening of the Silicon Shock\n  Hugoniot Curve: Shock compression of silicon (Si) under extremely high pressures (>100 Mbar)\nwas investigated by using two first-principles methods of orbital-free\nmolecular dynamics (OFMD) and path integral Monte Carlo (PIMC). While pressures\nfrom the two methods agree very well, PIMC predicts a second compression\nmaximum because of 1s electron ionization that is absent in OFMD calculations\nsince Thomas-Fermi-based theories lack shell structure. The Kohn-Sham density\nfunctional theory is used to calculate the equation of state (EOS) of warm\ndense silicon for low-pressure loadings (P < 100 Mbar). Combining these\nfirst-principles EOS results, the principal shock Hugoniot curve of silicon for\npressures varying from 1 Mbar to above 10 Gbar was derived. We find that\nsilicon is 20% or more softer than what was predicted by widely-used EOS\nmodels. Existing high-pressure experimental data (P = 1 - 2 Mbar) seem to\nindicate this softening behavior of Si, which calls for future strong-shock\nexperiments (P > 10 Mbar) to benchmark our results."
    },
    {
        "anchor": "Second-principles method including electron and lattice degrees of\n  freedom: We present a first-principles-based (second-principles) scheme that permits\nlarge-scale materials simulations including both atomic and electronic degrees\nof freedom on the same footing. The method is based on a predictive\nquantum-mechanical theory, e.g., Density Functional Theory, and its accuracy\ncan be systematically improved at a very modest computational cost. Our\napproach is based on dividing the electron density of the system into a\nreference part - typically corresponding to the system's neutral,\ngeometry-dependent ground state - and a deformation part - defined as the\ndifference between the actual and reference densities. We then take advantage\nof the fact that the bulk part of the system's energy depends on the reference\ndensity alone; this part can be efficiently and accurately described by a force\nfield, thus avoiding explicit consideration of the electrons. Then, the effects\nassociated to the difference density can be treated perturbatively with good\nprecision by working in a suitably chosen Wannier function basis. Further, the\nelectronic model can be restricted to the bands of interest. All these features\ncombined yield a very flexible and computationally very efficient scheme. Here\nwe present the basic formulation of this approach, as well as a practical\nstrategy to compute model parameters for realistic materials. We illustrate the\naccuracy and scope of the proposed method with two case studies, namely, the\nrelative stability of various spin arrangements in NiO and the formation of a\ntwo-dimensional electron gas at the interface between band insulators LaAlO$_3$\nand SrTiO$_3$. We conclude by discussing ways to overcome the limitations of\nthe present approach (most notably, the assumption of a fixed bonding\ntopology), as well as its many envisioned possibilities and future extensions.",
        "positive": "Design, theory, and measurement of a polarization insensitive absorber\n  for terahertz imaging: We present the theory, design, and realization of a polarization-insensitive\nmetamaterial absorber for terahertz frequencies. We derive\ngeometrical-independent conditions for effective medium absorbers in general,\nand for resonant metamaterials specically. Our fabricated design reaches and\nabsorptivity of 78% at 1.145 Thz"
    },
    {
        "anchor": "Coherent Atomically-Thin Superlattices with Engineered Strain: Epitaxy forms the basis of modern electronics and optoelectronics. We report\ncoherent atomically-thin superlattices, in which different transition metal\ndichalcogenide monolayers--despite large lattice mismatches--are repeated and\nintegrated without dislocations. Grown by a novel omnidirectional epitaxy,\nthese superlattices display fully-matched lattice constants across\nheterointerfaces while maintaining a surprisingly isotropic lattice structure\nand triangular symmetry. This strong epitaxial strain is precisely engineered\nvia the nanoscale supercell dimensions, thereby enabling broad tuning of the\noptical properties and producing photoluminescence peak shifts as large as 250\nmeV. We present theoretical models to explain this coherent growth as well as\nthe energetic interplay governing the flat-rippled configuration space in these\nstrained monolayers. Such coherent superlattices provide novel building blocks\nwith targeted functionalities at the atomically-thin monolayer limit.",
        "positive": "Borophane: Stable Two-dimensional Anisotropic Dirac Material with\n  Ultrahigh Fermi Velocity: Recent synthesis of monolayer borophene (triangle boron monolayer) on the\nsubstrate opens the era of boron nanosheet (Science, 350, 1513,\n$\\mathbf{2015}$), but the structural stability and novel physical properties\nare still open issues. Here we demonstrated borophene can be stabilized with\nfully surface hydrogenation, called as borophane, from first-principles\ncalculations. Most interesting, it shows that borophane has direction-dependent\nDirac cones, which are mainly contributed by in-plane \\emph{p$_{x}$} and\n\\emph{p$_{y}$} orbitals of boron atoms. The Dirac fermions possess an ultrahigh\nFermi velocity up to 3.0$\\times$10$^{6}$ m/s, 4 times higher than that of\ngraphene. The Young's modules are calculated to be 129 and 200 GPa$\\cdot$nm\nalong two different directions, which is comparable with steel. The ultrahigh\nFermi velocity and high mechanical feature render borophane ideal for\nnanoelectronics applications."
    },
    {
        "anchor": "Metallic Hydrogen Sublattice and Proton Mobility in Copper Hydride at\n  High Pressure: Atomic and electronic structures of Cu2H and CuH have been investigated by\nhigh pressure NMR spectroscopy, X-ray diffraction and ab-initio calculations.\nMetallic Cu2H was synthesized at a pressure of 40 GPa, and semi-metallic CuH at\n90 GPa, found stable up to 160 GPa. Experiments and computations suggest the\nformation of a metallic 1H-sublattice as well as a high 1H mobility of ~10-7\ncm2/s in Cu2H. Comparison of Cu2H and FeH data suggests that deviations from\nFermi gas behavior, formation of conductive hydrogen networks, and high 1H\nmobility could be common features of metal hydrides.",
        "positive": "Generating Weyl semimetals from alkali metals: We report the discovery of a time-reversal symmetric Weyl semimetal obtained\nby modifying a model Hamiltonian describing the electronic properties of\nconventional alkali metals. The artificially generated Weyl semimetal features\nfour isolated Weyl nodes in its bulk band structure and displays characteristic\nsurface Fermi arcs arising from topologically protected surface states. The\nWeyl semimetal occurs as an intermediate state between a conventional band\ninsulator and a three-dimensional topological insulator. The generation of\ntopological Weyl semimetals from conventional metals opens a new route towards\nthe deterministic design of simple materials hosting Weyl fermions."
    },
    {
        "anchor": "Structure of transition metal clusters: A force-biased Monte Carlo\n  approach: We present a force-biased Monte Carlo (FMC) method for structural modeling of\ntransition metal clusters of Fe, Ni, and Cu with 5 to 60 atoms. By employing\nthe Finnis-Sinclair potential for Fe and the Sutton-Chen potential for Ni and\nCu, the total energy of the clusters is minimized using a method that utilizes\natomic forces in Monte Carlo simulations. The structural configurations of the\nclusters obtained from this biased Monte Carlo approach are analyzed and\ncompared with the same from the Cambridge Cluster Database (CCD). The results\nshow that the total-energy of the FMC clusters is very close to the\ncorresponding value of the CCD clusters as listed in the Cambridge Cluster\nDatabase. A comparison of the FMC and CCD clusters is presented by computing\nthe pair-correlation function, the bond-angle distribution, and the\ndistribution of atomic-coordination numbers in the first-coordination shell,\nwhich provide information about the two-body and three-body correlation\nfunctions, the local atomic structure, and the bonding environment of the atoms\nin the clusters.",
        "positive": "Tunable Low Density Palladium Nanowire Foams: Nanostructured palladium foams offer exciting potential for applications in\ndiverse fields such as catalyst, fuel cell, and particularly hydrogen storage\ntechnologies. We have fabricated palladium nanowire foams using a cross-linking\nand freeze-drying technique. These foams have a tunable density down to 0.1% of\nthe bulk, and a surface area to volume ratio of up to 1,540,000:1. They exhibit\nhighly attractive characteristics for hydrogen storage, in terms of loading\ncapacity, rate of absorption and heat of absorption. The hydrogen\nabsorption/desorption process is hysteretic in nature, accompanied by\nsubstantial lattice expansion/contraction as the foam converts between Pd and\nPdHx."
    },
    {
        "anchor": "Elastic propagation of fast electron vortices through amorphous\n  materials: In this work, we study the elastic scattering behavior of electron vortices\nwhen propagating through amorphous samples. We use a formulation of the\nmultislice approach in cylindrical coordinates to theoretically investigate the\nredistribution of intensity between different angular momentum components due\nto scattering. To corroborate and elaborate on our theoretical results, we\nperform extensive numerical simulations on three model systems (Si$_3$N$_4$,\nFe$_{0.8}$B$_{0.2}$, Pt) for a wide variety of experimental parameters to\nquantify the purity of the vortices, the net angular momentum transfer, and the\nvariability of the results with respect to the random relative position between\nthe electron beam and the scattering atoms. These results will help scientists\nto further improve the creation of electron vortices and enhance applications\ninvolving them.",
        "positive": "Internal friction study of dislocation dynamics in thermally aged\n  Fe-1%Cu-C alloys: Internal friction study of dislocation dynamics in thermally aged Fe-1%Cu-C\nalloys."
    },
    {
        "anchor": "Ab initio many-body photoemission theory of transverse energy\n  distribution of photoelectrons: PbTe(111) as a case study with experimental\n  comparisons: This manuscript presents, to our knowledge, the first fully ab initio\nmany-body photoemission framework to predict the transverse momentum\ndistributions and the mean transverse energies (MTEs) of photoelectrons from\nsingle-crystal photocathodes. The need to develop such a theory stems from the\nlack of studies that provide complete understanding of the underlying\nfundamental processes governing the transverse momentum distribution of\nphotoelectrons emitted from single crystals. For example, initial predictions\nbased on density-functional theory calculations of effective electron masses\nsuggested that the (111) surface of PbTe would produce very small MTEs ($\\leq$\n15 meV), whereas our experiments yielded MTEs ten to twenty times larger than\nthese predictions, and also exhibited a lower photoemission threshold than\npredicted. The ab initio framework presented in this manuscript correctly\nreproduces the magnitude of the MTEs from our measurements in PbTe(111) and\nalso the observed photoemission below the predicted threshold. Our results show\nthat photoexcitations into bulk-like states and coherent, many-body\nelectron-photon-phonon scattering processes, both of which initial predictions\nignored, indeed play important roles in photoemission from PbTe(111). Finally,\nfrom the lessons learned, we recommend a procedure for rapid computational\nscreening of potential single-crystal photocathodes for applications in\nnext-generation ultrafast electron diffraction and X-ray free-electron lasers,\nwhich will enable new, significant advances in condensed matter research.",
        "positive": "Spin-Peierls transition in TiOCl: Temperature-dependent x-ray diffraction of the low-dimensional spin 1/2\nquantum magnet TiOCl shows that the phase transition at T_{c2} = 90 K\ncorresponds to a lowering of the lattice symmetry. Below T_{c1} = 66 K a\ntwofold superstructure develops, that indicates the formation of spin-singlet\npairs via direct exchange between neighboring Ti atoms, while the role of\nsuperexchange is found to be negligible. TiOCl thus is identified as a\nspin-Peierls system of pure 1D chains of atoms. The first-order character of\nthe transition at T_{c1} is explained by the competition between the\nstructurally deformed state below T_{c2} and the spin-Peierls state below\nT_{c1}."
    },
    {
        "anchor": "First Principles Phase Diagram Calculations for the\n  Octahedral-Interstitial System ZrO$_{X}$, $0 \\leq X \\leq 1/2$: First principles based phase diagram calculations were performed for the\noctahedral-interstitial solid solution system \\alpha ZrOX (\\alpha Zr[\n]_(1-X)OX; [ ]=Vacancy; 0 \\leq X \\leq 1/2). The cluster expansion method was\nused to do a ground state analysis, and to calculate the phase diagram. The\npredicted diagram has four ordered ground-states in the range 0 \\leq X \\leq\n1/2, but one of these, at X=5/12, is predicted to disproportionate at T \\approx\n20K, well below the experimentally investigated range T \\approx 420K. Thus, at\nT \\succeq 420K, the first-principles based calculation predicts three ordered\nphases rather than the four that have been reported by experimentalists.",
        "positive": "Metallurgical synthesis methods for Mg-Al-Ca scientific model materials: Mg-based alloys are industrially used for structural applications, both as\nsolid solutions alloys and as composites containing intermetallic compounds.\nHowever, a further development in terms of mechanical properties requires the\ninvestigation of underlying causalities between synthesis, processing and\nmicrostructure to adjust the mechanical and the corrosion properties, ideally\ndown to the near atomic scale. Such fundamental scientific investigations with\nhigh resolution characterisation techniques require model materials of\nexceptionally high purity and strictly controlled microstructure e.g. with\nrespect to grain size, morphology, chemical homogeneity as well as content and\nsize of oxide inclusions. In this context, the Mg-Al-Ca system appears\nexceptionally challenging from a metallurgical perspective due to the high\nreactivity and high vapor pressures, so that conventional industrial techniques\ncannot be successfully deployed. Here, we demonstrate the applicability of\nvarious scientific synthesis methods from arc melting over solution growth to\ndiffusion couples, extending to effects and parameters for thermo-mechanical\nprocessing. Suitable pathways to overcome the specific challenges of the\nMg-Al-Ca system are demonstrated, as well as the persistent limitations of the\ncurrent state of the art laboratory metallurgy technology."
    },
    {
        "anchor": "Tuning the Dirac point to the Fermi level in the ternary topological\n  insulator (Bi$_{1-x}$Sb$_{x}$)$_{2}$Te$_{3}$: In order to stabilize Majorana excitations within vortices of proximity\ninduced topological superconductors, it is mandatory that the Dirac point\nmatches the Fermi level rather exactly, such that the conventionally confined\nstates within the vortex are well separated from the Majorana-type excitation.\nHere, we show by angle resolved photoelectron spectroscopy that\n(Bi$_{1-x}$Sb$_{x}$)$_{2}$Te$_{3}$ thin films with $x=0.94$ prepared by\nmolecular beam epitaxy and transferred in ultrahigh vacuum from the molecular\nbeam epitaxy system to the photoemission setup matches this condition. The\nDirac point is within 10 meV around the Fermi level and we do not observe any\nbulk bands intersecting the Fermi level.",
        "positive": "Bipolar charge-carrier injection in semiconductor/insulator/conductor\n  heterostructures: self-consistent consideration: A self-consistent model of bipolar charge-carrier injection and transport\nprocesses in a semiconductor/insulator/conductor system is developed which\nincorporates space-charge effects in the description of the injection process.\nThe amount of charge-carriers injected is strongly determined by the energy\nbarrier emerging at the contact, but at the same time the electrostatic\npotential generated by the injected charge-carriers modifies the height of this\ninjection barrier itself. In our model, self-consistency is obtained by\nassuming continuity of the electric displacement and of the electrochemical\npotential all over the system. The constituents of the system are properly\ntaken into account by means of their respective density of state distributions.\nThe consequences resulting from our model are discussed on the basis of an\nindium tin oxide/organic semiconductor/conductor structure. The distributions\nof the charge carriers and the electric field through the electrodes and the\norganic layer are calculated. The recombination- and current-voltage\ncharacteristics are analyzed for different heights of injection barriers and\nvarying values of the recombination rate and compared with the measured\ncurrent-voltage dependences for an indium tin oxide/poly(phenylene vinylene)/Ca\nstructure. The voltage dependences of the recombination efficiency for the\ndifferent values of injection barriers and recombination rate reveal optimum\nconditions for the device performance."
    },
    {
        "anchor": "Thermal transport in SiC nanostructures: SiC is a robust semiconductor material considered ideal for high-power\napplication due to its material stability and large bulk thermal conductivity\ndefined by the very fast phonons. In this paper, however, we show that both\nmaterial-interface scattering and total-internal reflection significantly limit\nthe SiC-nanostructure phonon transport and hence the heat dissipation in a\ntypical device. For simplicity we focus on planar SiC nanostructures and\ncalculate the thermal transport both parallel to the layers in a\nsubstrate/SiC/oxide heterostructure and across a SiC/metal gate or contact. We\nfind that the phonon-interface scattering produces a heterostructure thermal\nconductivity significantly smaller than what is predicted in a traditional\nheat-transport calculation. We also document that the high-temperature heat\nflow across the metal/SiC interface is limited by total-internal reflection\neffects and maximizes with a small difference in the metal/SiC sound\nvelocities.",
        "positive": "Capturing Excitonic Effects in Lead Iodide Perovskites from Many-Body\n  Perturbation Theory: Lead iodide perovskites have attracted considerable interest in the upcoming\nphotovoltaic technologies and optoelectronic devices. Therefore, an accurate\ntheoretical description of the electronic and optical properties especially to\nunderstand the excitonic effects in this class of materials is of scientific\nand practical interest. However, despite several theoretical research\nendeavours in past, the most accurate analysis of the key electronic parameters\nfor solar cell performance, such as optical properties, effective mass, exciton\nbinding energy (E$_B$) and the radiative exciton lifetime are still largely\nunknown. Here, we employ state-of-the-art first-principles based methodologies\nviz. hybrid functional(HSE06) combined with spin-orbit coupling (SOC),\nmany-body perturbation theory (GW, BSE), model-BSE (mBSE), Wannier-Mott (WM)\nand Density Functional Perturbation Theory (DFPT). By taking a prototypical\nmodel system viz. APbI$_3$ (A = Formamidinium (FA), methylammonium (MA), and\nCs), an exhaustive analysis is presented on the theoretical understanding of\nthe optical, electronic and excitonic properties. We show that tuning of exact\nexchange parameter ($\\alpha$) in HSE06 calculations incorporating SOC, followed\nby single shot GW, and BSE play a pivotal role in obtaining a reliable\npredictions for the experimental bandgap. We demonstrate that mBSE approach\nimproves the feature of optical spectra w.r.t experiments. Furthermore, WM\napproach and ionic contribution to dielectric screening (below 16 meV)\nameliorate the E$_B$. Our results reveal that the direct-indirect band gap\ntransition (Rashba splitting) may be a factor responsible for the reduced\ncharge carrier recombination rate in MAPbI$_3$ and FAPbI$_3$. The role of\ncation ''A'' for procuring the long-lived exciton lifetime is well understood.\nThis proposed methodology allows to design new materials with tailored\nexcitonic properties."
    },
    {
        "anchor": "The effect of finite-temperature and anharmonic lattice dynamics on the\n  thermal conductivity of ZrS2 monolayer: self-consistent phonon calculations: Two-dimensional (2D) ZrS2 monolayer (ML) has emerged as a promising candidate\nfor thermoelectric (TE) device applications due to its high TE figure of merit,\nwhich is mainly contributed by its inherently low lattice thermal conductivity.\nThis work investigates the effect of the lattice anharmonicity driven by\ntemperature-dependent phonon dispersions on thermal transport of ZrS2 ML. The\ncalculations are based on the self-consistent phonon (SCP) theory to calculate\nthe thermodynamic parameters along with the lattice thermal conductivity. The\nhigher- order (quartic) force constants were extracted by using an efficient\ncompressive sensing lattice dynamics technique, which estimates the necessary\ndata based on the emerging machine learning program as an alternative of\ncomputationally expensive density functional theory calculations. Resolve of\nthe degeneracy and hardening of the vibrational frequencies of low-energy\noptical modes were predicted upon including the quartic anharmonicity. As\ncompared to the conventional Boltzmann transport equation (BTE) approach, the\nlattice thermal conductivity of the optimized ZrS2 ML unit cell within SCP +\nBTE approach is found to be significantly enhanced (e.g., by 21% at 300 K).\nThis enhancement is due to the relatively lower value of phonon linewidth\ncontributed by the anharmonic frequency renormalization included in the SCP\ntheory. Mainly, the conventional BTE approach neglects the temperature\ndependence of the phonon frequencies due to the consideration of harmonic\nlattice dynamics and treats the normal process of three-phonon scattering\nincorrectly due to the use of quasi-particle lifetimes. These limitations are\naddressed in this work within the SCP + BTE approach, which signifies the\nvalidity and accuracy of this approach.",
        "positive": "Matching Conditions in Atomistic-Continuum Modeling of Materials: A new class of matching condition between the atomistic and continuum regions\nis presented for the multi-scale modeling of crystals. They ensure the accurate\npassage of large scale information between the atomistic and continuum regions\nand at the same time minimize the reflection of phonons at the interface. These\nmatching conditions can be made adaptive if we choose appropriate weight\nfunctions. Applications to dislocation dynamics and friction between\ntwo-dimensional atomically flat crystal surfaces are described."
    },
    {
        "anchor": "Intercalation of metal into transition metal dichalcogenides in molten\n  salts: Van der Waals (vdW) layered materials have drawn tremendous interests due to\ntheir unique properties. Atom intercalation in the vdW gap of layered materials\ncan tune their electronic structure and generate unexpected properties. Here we\nreport a chemical-scissor mediated method that enables metal intercalation into\ntransition metal dichalcogenides (TMDCs) in molten salts. By using this\napproach, various guest metal atoms (Mn, Fe, Co, Ni, Cu, and Ag) were\nintercalated into various TMDCs hosts (such as TiS2, NbS2, TaS2, TiSe2, NbSe2,\nTaSe2 and Ti0.5V0.5S2). The structure of the intercalated compound and\nintercalation mechanism was investigated. The results indicate that the vdW gap\nand valence state of TMDCs can be modified through metal intercalation, and the\nintercalation behavior is dictated by the electron work function. Such a\nchemical-scissor mediated intercalation provides an approach to tune the\nphysical and chemical properties of TMDCs, which may open an avenue in\nfunctional application ranging from energy conversion to electronics.",
        "positive": "Excitonic parameters of InxGa1-xAs-GaAs heterostructures with quantum\n  wells at low temperatures: Characteristics of GaAs/In$_{x}$Ga$_{1-x}$As/GaAs heterostructures with a\nsingle quantum well, which were obtained at various growth parameters, are\nevaluated according to the results of measurements of low-temperature\nphotoluminescence spectra and their corresponding theoretical analysis."
    },
    {
        "anchor": "Contribution of inter- and intraband transitions into electron-phonon\n  coupling in metals: We recently developed an approach for calculation of the electron-phonon\n(electron-ion in a more general case) coupling in materials based on\ntight-binding molecular dynamics simulations. In the present work we utilize\nthis approach to study partial contributions of inter- and intraband electron\nscattering events into total electron-phonon coupling in Al, Au, Cu elemental\nmetals and in AlCu alloy. We demonstrate that the interband scattering plays an\nimportant role in electron-ion energy exchange process in Al and AlCu, whereas\nintraband $d-d$ transitions are dominant in Au and Cu. Moreover, inter- and\nintraband transitions exhibit qualitatively different dependencies on the\nelectron temperature. Our findings should be taken into account for\ninterpretation of experimental results on electron-phonon coupling parameter.",
        "positive": "Spectrally narrow exciton luminescence from monolayer MoS2 exfoliated\n  onto epitaxially grown hexagonal BN: The strong light-matter interaction in transition Metal dichalcogenides\n(TMDs) monolayers (MLs) is governed by robust excitons. Important progress has\nbeen made to control the dielectric environment surrounding the MLs, especially\nthrough hexagonal boron nitride (hBN) encapsulation, which drastically reduces\nthe inhomogeneous contribution to the exciton linewidth. Most studies use\nexfoliated hBN from high quality flakes grown under high pressure. In this\nwork, we show that hBN grown by molecular beam epitaxy (MBE) over a large\nsurface area substrate has a similarly positive impact on the optical emission\nfrom TMD MLs. We deposit MoS$_2$ and MoSe$_2$ MLs on ultrathin hBN films (few\nMLs thick) grown on Ni/MgO(111) by MBE. Then we cover them with exfoliated hBN\nto finally obtain an encapsulated sample : exfoliated hBN/TMD ML/MBE hBN. We\nobserve an improved optical quality of our samples compared to TMD MLs\nexfoliated directly on SiO$_2$ substrates. Our results suggest that hBN grown\nby MBE could be used as a flat and charge free substrate for fabricating\nTMD-based heterostructures on a larger scale."
    },
    {
        "anchor": "Global Structure Search for Molecules on Surfaces: Efficient Sampling\n  with Curvilinear Coordinates: Efficient structure search is a major challenge in computational materials\nscience. We present a modification of the basin hopping global geometry\noptimization approach that uses a curvilinear coordinate system to describe\nglobal trial moves. This approach has recently been shown to be efficient in\nstructure determination of clusters [Nano Letters 15, 8044-8048 (2015)] and is\nhere extended for its application to covalent, complex molecules and large\nadsorbates on surfaces. The employed, automatically constructed delocalized\ninternal coordinates are similar to molecular vibrations, which enhances the\ngeneration of chemically meaningful trial structures. By introducing flexible\nconstraints and local translation and rotation of independent geometrical\nsubunits we enable the use of this method for molecules adsorbed on surfaces\nand interfaces. For two test systems, trans-$\\beta$-ionylideneacetic acid\nadsorbed on a Au(111) surface and methane adsorbed on a Ag(111) surface, we\nobtain superior performance of the method compared to standard optimization\nmoves based on Cartesian coordinates.",
        "positive": "BerkeleyGW: A Massively Parallel Computer Package for the Calculation of\n  the Quasiparticle and Optical Properties of Materials and Nanostructures: BerkeleyGW is a massively parallel computational package for electron\nexcited-state properties that is based on the many-body perturbation theory\nemploying the ab initio GW and GW plus Bethe-Salpeter equation methodology. It\ncan be used in conjunction with many density-functional theory codes for\nground-state properties, including PARATEC, PARSEC, Quantum ESPRESSO, OCTOPUS\nand SIESTA. The package can be used to compute the electronic and optical\nproperties of a wide variety of material systems from bulk semiconductors and\nmetals to nanostructured materials and molecules. The package scales to\n10,000's of CPUs and can be used to study systems containing up to 100's of\natoms."
    },
    {
        "anchor": "Pulsed laser deposition growth of heteroepitaxial\n  YBa2Cu3O7/La0.67Ca0.33MnO3 superlattices on NdGaO3 and\n  Sr0.7La0.3Al0.65Ta0.35O3 substrates: Heteroepitaxial superlattices of [YBa2Cu3O7(n)/ La0.67Ca0.33MnO3(m)]x, where\nn and m are the number of YBCO and LCMO monolayers and x the number of bilayer\nrepetitions, have been grown with pulsed laser deposition on NdGaO3 (110) and\nSr0.7La0.3Al0.65Ta0.35O3 (LSAT) (001). These substrates are well lattice\nmatched with YBCO and LCMO and, unlike the commonly used SrTiO3, they do not\ngive rise to complex and uncontrolled strain effects due to structural\ntransitions at low temperature. The growth dynamics and the structure have been\nstudied in-situ with reflection high energy electron diffraction (RHEED) and\nex-situ with scanning transmission electron microscopy (STEM), x-ray\ndiffraction, and neutron reflectometry. The individual layers are found to be\nflat and continuous over long lateral distances with sharp and coherent\ninterfaces and with a well-defined thickness of the individual layer. The only\nvisible defects are antiphase boundaries in the YBCO layers that originate from\nperovskite unit cell height steps at the interfaces with the LCMO layers. We\nalso find that the first YBCO monolayer at the interface with LCMO has an\nunusual growth dynamics and is lacking the CuO chain layer while the subsequent\nYBCO layers have the regular Y-123 structure. Accordingly, the CuO2 bilayers at\nboth the LCMO/YBCO and the YBCO/LCMO interfaces are lacking one of their\nneighboring CuO chain layers and thus half of their hole doping reservoir.\nNevertheless, from electric transport measurements on asuperlattice with n=2 we\nobtain evidence that the interfacial CuO2 bilayers remain conducting and even\nexhibit the onset of a superconducting transition at very low temperature.\nFinally, we show from dc magnetization and neutron reflectometry measurements\nthat the LCMO layers are strongly ferromagnetic.",
        "positive": "Chemical potential dependent gap-opening at the Dirac surface states of\n  Bi2Se3 induced by aggregated substitutional Cr atoms: With angle-resolved photoemission spectroscopy, gap-opening is resolved at up\nto room temperature in the Dirac surface states of molecular beam epitaxy grown\nCr-doped Bi2Se3 topological insulator films, which however show no long-range\nferromagnetic order down to 1.5 K. The gap size is found decreasing with\nincreasing electron doping level. Scanning tunneling microscopy and first\nprinciples calculations demonstrate that substitutional Cr atoms aggregate into\nsuperparamagnetic multimers in Bi2Se3 matrix, which contribute to the observed\nchemical potential dependent gap-opening in the Dirac surface states without\nlong-range ferromagnetic order."
    },
    {
        "anchor": "Atomic level understanding of site-specific interactions in\n  Polyaniline/TiO2 composite: The results of spin-polarized density functional theory calculations find\nthat band gap engineering can be achieved by site-specific interactions in a\ncomposite consisting of polyaniline and TiO2 nanoparticles. Interactions in the\ncomposite matrix are found to be mediated by Ti atoms inducing dependency of\nlocation of the conduction band minimum on the polyaniline site which is being\nprobed by TiO2. This dependency is due to subtle changes in the nature of\nvalance or conduction states near Fermi level introduced by the interacting\nmatrix sites. The results therefore suggest that optimization of the synthesis\nparameters at atomic level can be an effective way to improve performance of a\nphotovoltaic device based on PAni- TiO2 composite.",
        "positive": "Epitaxial-strain-induced multiferroicity in SrMnO$_{3}$ from first\n  principles: First-principles density-functional calculations reveal a large spin-phonon\ncoupling in cubic SrMnO$_{3}$, with ferromagnetic ordering producing a polar\ninstability. Through combination of this coupling with the strain-polarization\ncoupling characteristic of perovskites, the bulk antiferromagnetic paraelectric\nground state of SrMnO$_3$ is shown to be driven to a previously unreported\nmultiferroic ferroelectric-ferromagnetic state by increasing epitaxial strain,\nboth tensile and compressive. This state has a computed polarization and\nestimated Curie temperature above 54 $\\mu$C/cm$^2$ and 92 K. Large mixed\nmagnetic-electric-elastic responses are predicted in the vicinity of the phase\nboundaries."
    },
    {
        "anchor": "Theoretical and experimental investigation of optical absorption\n  anisotropy in $\u03b2$-Ga2O3: The question of optical bandgap anisotropy in the monoclinic semiconductor\n$\\beta$-Ga2O3 was revisited by combining accurate optical absorption\nmeasurements with theoretical analysis, performed using different advanced\ncomputation methods. As expected, the bandgap edge of bulk $\\beta$-Ga2O3 was\nfound to be a function of light polarization and crystal orientation, with the\nlowest onset occurring at polarization in the ac crystal plane around 4.5-4.6\neV; polarization along b unambiguously shifts the onset up by 0.2 eV. The\ntheoretical analysis clearly indicates that the shift of the b onset is due to\na suppression of the transition matrix elements of the three top valence bands\nat $\\Gamma$ point.",
        "positive": "Anomalous thermal expansion in $\u03b1$-titanium: We provide a complete quantitative explanation for the anisotropic thermal\nexpansion of hcp Ti at low temperature. The observed negative thermal expansion\nalong the c-axis is reproduced theoretically by means of a parameter free\ntheory which involves both the electron and phonon contributions to the free\nenergy. The thermal expansion of titanium is calculated and found to be\nnegative along the c-axis for temperatures below $\\sim$ 170 K, in good\nagreement with observations. We have identified a saddle-point Van Hove\nsingularity near the Fermi level as the main reason for the anisotropic thermal\nexpansion in $\\alpha-$titanium."
    },
    {
        "anchor": "Electronic structure and symmetry of valence states of epitaxial NiTiSn\n  and NiZr$_{0.5}$Hf$_{0.5}$Sn thin films by hard x-ray photoelectron\n  spectroscopy: The electronic band structure of thin films and superlattices made of Heusler\ncompounds with NiTiSn and NiZr$_{0.5}$Hf$_{0.5}$Sn composition was studied by\nmeans of polarization dependent hard x-ray photoelectron spectroscopy. The\nlinear dichroism allowed to distinguish the symmetry of the valence states of\nthe different types of layered structures. The films exhibit a larger amount of\n{\\it \"in-gap\"} states compared to bulk samples. It is shown that the films and\nsuperlattices grown with NiTiSn as starting layer exhibit an electronic\nstructure close to bulk materials.",
        "positive": "Validity of the N\u00e9el-Arrhenius model for highly anisotropic\n  Co_xFe_{3-x}O_4 nanoparticles: We report a systematic study on the structural and magnetic properties of\nCo_{x}Fe_{3-x}O_{4} magnetic nanoparticles with sizes between $5$ to $25$ nm,\nprepared by thermal decomposition of Fe(acac)_{3} and Co(acac)_{2}. The large\nmagneto-crystalline anisotropy of the synthesized particles resulted in high\nblocking temperatures ($42$ K \\leqq $T_B$ $\\leqq 345$ K for $5 \\leqq$ d $\\leqq\n13$ nm ) and large coercive fields ($H_C \\approxeq 1600$ kA/m for $T = 5$ K).\nThe smallest particles ($<d>=5$ nm) revealed the existence of a magnetically\nhard, spin-disordered surface. The thermal dependence of static and dynamic\nmagnetic properties of the whole series of samples could be explained within\nthe N\\'{e}el-Arrhenius relaxation framework without the need of ad-hoc\ncorrections, by including the thermal dependence of the magnetocrystalline\nanisotropy constant $K_1(T)$ through the empirical Br\\\"{u}khatov-Kirensky\nrelation. This approach provided $K_1(0)$ values very similar to the bulk\nmaterial from either static or dynamic magnetic measurements, as well as\nrealistic values for the response times ($\\tau_0 \\simeq 10^{-10}$ s).\nDeviations from the bulk anisotropy values found for the smallest particles\ncould be qualitatively explained based on Zener\\'{}s relation between $K_1(T)$\nand M(T)."
    },
    {
        "anchor": "Magnetic and transport properties of Mo substituted\n  La0.67Ba0.33Mn1-xMoxO3 perovskite system: The effect of doping Mo for Mn on the magnetic and transport properties of\nthe colossal magnetoresistance material, La0.67Ba0.33MnO3, has been studied.\nCompounds of the series La0.67Ba0.33Mn1-xMoxO3 (x=0.0 to 0.1) have been\nprepared and found to crystallize in the orthorhombic structure (space group\nPbnm). Energy Dispersive X-ray Analysis (EDAX) measurements confirm the\nstoichiometry of all the samples. Magnetotransport and magnetization\nmeasurements reveal that the metal-insulator transition temperature (Tp)\ndecreases from 330K for x=0 to 255K for x=0.1. The change in Tp on Mo\nsubstitution is relatively much smaller than the corresponding change observed\non substitution by other transition elements, such as Ti, Fe, Co, Ni, etc.\nFurther, the ferromagnetic transition temperature (TC) is nearly unchanged by\nMo substitution. This is in striking contrast to the large decrease in TC\nobserved with substitution of above-mentioned 3d elements. These unusual\nmagnetic and transport properties of La0.67Ba0.33Mn1-xMoxO3 may be either due\nto the formation of magnetic pair between Mn and Mo or due to strong\nMo(4d)-O(2p) overlap, which in turn, may affect the Mn-Mn interaction via the\noxygen atoms",
        "positive": "Edge-Soliton-Mediated Vortex-Core Reversal Dynamics: We report a new reversal mechanism of magnetic vortex cores in nanodot\nelements driven by out-of-plane currents, occurring through two coupled\nedge-solitons via dynamic transformations between magnetic solitons of\ndifferent topological charges. This mechanism differs completely from the well\nknown switching process mediated by the creation and annihilation of\nvortex-antivortex pairs in terms of the associated topological solitons,\nenergies, and spin-wave emissions. Strongly localized out-of-plane gyrotropic\nfields induced by the fast motion of the two coupled edge-solitons enable a\nmagnetization dip that plays a crucial role in the formation of the reversed\ncore magnetization. This work provides a new physical insight into the dynamic\ntransformations of magnetic solitons in nanoelements."
    },
    {
        "anchor": "Optical and electronic properties of sub-surface conducting layers in\n  diamond created by MeV B-implantation at elevated temperatures: Boron implantation with in-situ dynamic annealing is used to produce highly\nconductive sub-surface layers in type IIa (100) diamond plates for the search\nof a superconducting phase transition. Here we demonstrate that high-fluence\nMeV ion-implantation, at elevated temperatures avoids graphitization and can be\nused to achieve doping densities of 6 at.%. In order to quantify the diamond\ncrystal damage associated with implantation Raman spectroscopy was performed,\ndemonstrating high temperature annealing recovers the lattice. Additionally,\nlow-temperature electronic transport measurements show evidence of charge\ncarrier densities close to the metal-insulator-transition. After electronic\ncharacterization, secondary ion mass spectrometry was performed to map out the\nion profile of the implanted plates. The analysis shows close agreement with\nthe simulated ion-profile assuming scaling factors that take into account an\naverage change in diamond density due to device fabrication. Finally, the data\nshow that boron diffusion is negligible during the high temperature annealing\nprocess.",
        "positive": "Perturbation of a lattice spectral band by a nearby resonance: A soluble model of weakly coupled \"molecular\" and \"nuclear\" Hamiltonians is\nstudied in order to exhibit explicitly the mechanism leading to the enhancement\nof fusion probability in case of a narrow near-threshold nuclear resonance. We,\nfurther, consider molecular cells of this type being arranged in lattice\nstructures. It is shown that if the real part of the narrow nuclear resonance\nlies within the molecular band generated by the intercellular interaction, an\nenhancement, proportional to the inverse width of the nuclear resonance, is to\nbe expected."
    },
    {
        "anchor": "Origin of giant spin-lattice coupling and the suppression of\n  ferroelectricity in EuTiO3 from first principles: We elucidate the microscopic mechanism that causes a suppression of\nferroelectricity and an enhancement of octahedral rotations in EuTiO3 from\nfirst principles. We find that the hybridization of the rare-earth Eu 4f states\nwith the B-site Ti cation drives the system away from ferroelectricity. We also\nshow that the magnetic order dependence of this hybridization is the dominant\nsource of spin-phonon coupling in this material. Our results underline the\nimportance of rare-earth f electrons on the lattice dynamics and stability of\nthese transition metal oxides.",
        "positive": "Inversion of the Diffraction Pattern from an Inhomogeneously Strained\n  Crystal using an Iterative Algorithm: The displacement field in highly non uniformly strained crystals is obtained\nby addition of constraints to an iterative phase retrieval algorithm. These\nconstraints include direct space density uniformity and also constraints to the\nsign and derivatives of the different components of the displacement field.\nThis algorithm is applied to an experimental reciprocal space map measured\nusing high resolution X-ray diffraction from an array of silicon lines and the\nobtained component of the displacement field is in very good agreement with the\none calculated using a finite element model."
    },
    {
        "anchor": "Causality and Passivity in Elastodynamics: What are the constraints placed on the frequency dependent constitutive\ntensors of elastodynamics by the requirements that the linear elastodynamic\nsystem under consideration be both causal (effects succeed causes) and passive\n(system doesn't produce energy)? Compared to electromagnetism, elastodynamics\nis complicated by its generally non diagonalizable constitutive tensors. In\nthis paper we clarify the constraints that causality and passivity place on\nvery general forms of elastodynamic constitutive relations. Specifically we\nshow that the satisfaction of passivity (and causality) directly requires that\nthe hermitian parts, as defined later, of the Fourier transforms of the time\nderivatives of the elastodynamic constitutive tensors be positive semi-definite\nat all frequencies. Additionally, we show that the conditions subsequently\nrequire that the non-hermitian parts of the Fourier transforms of the\nconstitutive tensors, when divided by the imaginary number $i$, be positive\nsemi-definite for positive values of frequency and negative semi-definite for\nnegative values of frequency. We show that when major symmetries are assumed\nthese definiteness relations apply simply to the real and imaginary parts of\nthe relevant tensors. For diagonal and one-dimensional problems, these positive\nsemi-definiteness relationships reduce to simple inequality relations. Finally\nwe extend the results to highly general constitutive relations which include\nthe Willis inhomogeneous relations as a special case.",
        "positive": "Electronic Structure of a Two-Dimensional Graphene-Like Topological\n  Insulator, Bi14Rh3I9: Very recently, a new two-dimensional graphene-like topological insulator,\nBi14Rh3I9, has been synthesized. The Bi-Rh sheets with a strong spin-orbit\ninteraction are graphene analogues with a honeycomb net composed of RhBi8\ncubes. Here we derive the low-energy effective Hamiltonian involving spin-orbit\ncoupling for Bi14Rh3I9. In the absence of spin-orbit coupling, the Bi-Rh sheets\nshow two inequivalent Dirac cones at the corners of the hexagonal Brillouin\nzone. The spin-orbit interaction opens a 2400 K bandgap at the Dirac points and\nestablishes the quantum spin Hall effect in the Bi-Rh sheets. Our result\nindicates that the Bi14Rh3I9 may combine many unique electronic properties of\ngraphene and topological insulators, and it should host a combination of\nquantum valley and spin Hall effects."
    },
    {
        "anchor": "Comparison of first-principles methods to extract magnetic parameters in\n  ultra-thin films: Co/Pt(111): We compare three distinct computational approaches based on first-principles\ncalculations within density functional theory to explore the magnetic exchange\nand the Dzyaloshinskii-Moriya interactions (DMI) of a Co monolayer on Pt(111),\nnamely (i) the method of infinitesimal rotations of magnetic moments based on\nthe Korringa-Kohn-Rostoker (KKR) Green function method, (ii) the generalized\nBloch theorem applied to spiraling magnetic structures and (iii) supercell\ncalculations with non-collinear magnetic moments, the latter two being based on\nthe full-potential linearized augmented plane wave (FLAPW) method. In\nparticular, we show that the magnetic interaction parameters entering\nmicromagnetic models describing the long-wavelength deviations from the\nferromagnetic state might be different from those calculated for fast rotating\nmagnetic structures, as they are obtained by using (necessarily rather small)\nsupercell or large spin-spiral wave-vectors. In the micromagnetic limit, which\nwe motivate to use by an analysis of the Fourier components of the domain-wall\nprofile, we obtain consistent results for the spin stiffness and DMI\nspiralization using methods (i) and (ii). The calculated spin stiffness and\nCurie temperature determined by subsequent Monte Carlo simulations are\nconsiderably higher than estimated from the bulk properties of Co, a\nconsequence of a significantly increased nearest-neighbor exchange interaction\nin the Co-monolayer (+50%). The calculated results are carefully compared with\nthe literature.",
        "positive": "Electron-phonon relaxation and excited electron distribution in gallium\n  nitride: We develop a theory of energy relaxation in semiconductors and insulators\nhighly excited by the long-acting external irradiation. We derive the equation\nfor the non-equilibrium distribution function of excited electrons. The\nsolution for this function breaks up into the sum of two contributions. The\nlow-energy contribution is concentrated in a narrow range near the bottom of\nthe conduction band. It has the typical form of a Fermi distribution with an\neffective temperature and chemical potential. The effective temperature and\nchemical potential in this low-energy term are determined by the intensity of\ncarriers' generation, the speed of electron-phonon relaxation, rates of\ninter-band recombination and electron capture on the defects. In addition,\nthere is a substantial high-energy correction. This high-energy 'tail' covers\nlargely the conduction band. The shape of the high-energy 'tail' strongly\ndepends on the rate of electron-phonon relaxation but does not depend on the\nrates of recombination and trapping. We apply the theory to the calculation of\na non-equilibrium distribution of electrons in irradiated GaN. Probabilities of\noptical excitations from the valence to conduction band and electron-phonon\ncoupling probabilities in GaN were calculated by the density functional\nperturbation theory. Our calculation of both parts of distribution function in\ngallium nitride shows that when the speed of electron-phonon scattering is\ncomparable with the rate of recombination and trapping then the contribution of\nthe non-Fermi 'tail' is comparable with that of the low-energy Fermi-like\ncomponent. So the high-energy contribution can affect essentially the charge\ntransport in the irradiated and highly doped semiconductors."
    },
    {
        "anchor": "First-principles study on Small Polaron and Li diffusion in layered\n  LiCoO2: Li-ion conductivity is one of the essential properties that determine the\nperformance of cathode materials for Li-ion batteries. Here, using the density\nfunctional theory, we investigate the polaron stability and its effect on the\nLi-ion diffusion in layered LiCoO2 with different magnetic orderings. The\nlocalized Co4+ polaron appears in the magnetic configurations and sets the\nLi-diffusion barrier of ~0.34 eV. The polaron also migrates in the opposite\ndirection to the Li-diffusion direction. On the other hand, the polaron does\nnot form in the non-magnetic structure, and the Li diffusion barrier without\nthe polaron is 0.21 eV. Although the existence of the polaron increases the\ndiffusion barrier, the magnetically ordered structures are more energetically\nstable during the migration than the non-magnetic case. Thus, our work\nadvocates the hole polaron migration scenario for Li-ion diffusion. Moreover,\nwe demonstrate that the strong electron correlation of Co ions plays an\nessential role in stabilizing the Co4+ polaron.",
        "positive": "High-dimensional Bayesian Optimization of Hyperparameters for an\n  Attention-based Network to Predict Materials Property: a Case Study on\n  CrabNet using Ax and SAASBO: Expensive-to-train deep learning models can benefit from an optimization of\nthe hyperparameters that determine the model architecture. We optimize 23\nhyperparameters of a materials informatics model, Compositionally-Restricted\nAttention-Based Network (CrabNet), over 100 adaptive design iterations using\ntwo models within the Adaptive Experimentation (Ax) Platform. This includes a\nrecently developed Bayesian optimization (BO) algorithm, sparse axis-aligned\nsubspaces Bayesian optimization (SAASBO), which has shown exciting performance\non high-dimensional optimization tasks. Using SAASBO to optimize CrabNet\nhyperparameters, we demonstrate a new state-of-the-art on the experimental band\ngap regression task within the materials informatics benchmarking platform,\nMatbench (~4.5% decrease in mean absolute error (MAE) relative to incumbent).\nCharacteristics of the adaptive design scheme as well as feature importances\nare described for each of the Ax models. SAASBO has great potential to both\nimprove existing surrogate models, as shown in this work, and in future work,\nto efficiently discover new, high-performing materials in high-dimensional\nmaterials science search spaces."
    },
    {
        "anchor": "Domain walls of ferroelectric BaTiO3 within the\n  Ginzburg-Landau-Devonshire phenomenological model: Mechanically compatible and electrically neutral domain walls in tetragonal,\northorhombic and rhombohedral ferroelectric phases of BaTiO3 are systematically\ninvestigated in the framework of the phenomenological\nGinzburg-Landau-Devonshire (GLD) model with parameters of Ref. [Hlinka and\nMarton, Phys. Rev. 74, 104104 (2006)]. Polarization and strain profiles within\ndomain walls are calculated numerically and within an approximation leading to\nthe quasi-one-dimensional analytic solutions applied previously to the\nferroelectric walls of the tetragonal phase [W. Cao and L.E. Cross, Phys. Rev.\n44, 5 (1991)]. Domain wall thicknesses and energy densities are estimated for\nall mechanically compatible and electrically neutral domain wall species in the\nentire temperature range of ferroelectric phases. The model suggests that the\nlowest energy walls in the orthorhombic phase of BaTiO3 are the 90-degree and\n60-degree walls. In the rhombohedral phase, the lowest energy walls are the\n71-degree and 109-degree walls. All these ferroelastic walls have thickness\nbelow 1 nm except for the 90-degree wall in the tetragonal phase and the\n60-degree S-wall in the orthorhombic phase, for which the larger thickness of\nthe order of 5 nm was found. The antiparallel walls of the rhombohedral phase\nhave largest energy and thus they are unlikely to occur. The calculation\nindicates that the lowest energy structure of the 109-degree wall and few other\ndomain walls in the orthorhombic and rhombohedral phases resemble Bloch-like\nwalls known from magnetism.",
        "positive": "Frequency non-reciprocity of surface spin wave in Permalloy thin films: Surface spin waves in thin Permalloy films are studied by means of\npropagative spin wave spectroscopy. We observe a systematic difference of up to\nseveral tens of MHz when comparing the frequencies of counter-propagating\nwaves. This frequency non-reciprocity effect is modeled using an analytical\ndipole-exchange theory that considers the mutual influence of non-reciprocal\nspin wave modal profiles and differences in magnetic anisotropies at the two\nfilm surfaces. At moderate film thickness (20 nm and below), the frequency\nnon-reciprocity scales linearly with the wave vector and quadratically with the\nthickness, whereas a more complex non-monotonic behavior is observed at larger\nthickness. Our work suggests that surface wave frequency non-reciprocity can be\nused as an accurate spectroscopic probe of magnetic asymmetries in thin\nferromagnetic films."
    },
    {
        "anchor": "Bifurcation of the Kirkendall marker plane and the role of Ni and other\n  impurities on the growth of Kirkendall voids in the Cu Sn system: The presence of bifurcation of the Kirkendall marker plane, a very special\nphenomenon discovered recently, is found in a technologically important Cu Sn\nsystem. It was predicted based on estimated diffusion coefficients; however,\ncould not be detected following the conventional inert marker experiments. As\nreported in this study, we could detect the locations of these planes based on\nthe microstructural features examined in SEM and TEM. This strengthens the\nconcept of the physicochemical approach that relates microstructural evolution\nwith the diffusion rates of components and imparts finer understanding of the\ngrowth mechanism of phases. The estimated diffusion coefficients at the\nKirkendall marker planes indicates that the reason for the growth of the\nKirkendall voids is the nonconsumption of excess vacancies which are generated\ndue to unequal diffusion rate of components. Systematic experiments using\ndifferent purity of Cu in this study indicates the importance of the presence\nof impurities on the growth of voids, which increases drastically for greather\nthan 0.1 wt percent impurity. The growth of voids increases drastically for\nelectroplated Cu, commercially pure Cu and Cu(0.5 at percent Ni) indicating the\nadverse role of both inorganic and organic impurities. Void size and number\ndistribution analysis indicates the nucleation of new voids along with the\ngrowth of existing voids with the increase in annealing time. The newly found\nlocation of the Kirkendall marker plane in the Cu3Sn phase indicates that voids\ngrow on both the sides of this plane which was not considered earlier for\ndeveloping theoretical models.",
        "positive": "Lack of Pinning for Rigid Sliding Monolayers in Microbalance Experiments: Recent work on the dynamics of monolayers on a metallic substrate attached to\na quartz oscillator has provided interesting data on kinetic friction at the\nmicroscopic level. Sliding of the film relative to the substrate is often\nobserved even in situations in which theory seems to predict that the film\nshould be pinned by substrate imperfections. In this letter we propose, in\norder to attempt to resolve this issue, that if the defect potentials have a\nrange of a little more than an atomic spacing, the net forces on the film due\nto the defects are likely to be quite small due to cancellations."
    },
    {
        "anchor": "Single channel conductance of H$_2$ molecules attached to platinum or\n  palladium electrodes: We report a detailed theoretical study of the bonding and conduction\nproperties of an hydrogen molecule joining either platinum or palladium\nelectrodes. We show that an atomic arrangement where the molecule is placed\nperpendicular to the electrodes is unstable for all distances between\nelectrodes. In contrast, the configuration where the molecule bridges the\nelectrodes is stable in a wide range of distances. In this last case the\nbonding state of the molecule does not hybridize with the leads and remains\nlocalized within the junction. As a result, this state does not transmit charge\nso that electronic transport is carried only through the anti-bonding state.\nThis fact leads to conductances of 1 $G_0$ at most, where $G_0=2e^2/h$. We\nindeed find that G is equal to 0.9 and 0.6 $G_0$ for Pt and Pd contacts\nrespectively.",
        "positive": "A novel two-dimensional all-carbon Dirac node-line semimetal: Carbon allotropes have vast potential in various applications, including\nsuperconductivity, energy storage, catalysis, and photoelectric semiconductor\ndevices. Recently, there has been significant research interest in exploring\nnew carbon materials that exhibit unique electronic structures. Here, we\npropose a novel two-dimensional (2D) carbon allotrope called TCH-SSH-2D, which\npossesses a Dirac node-line (DNL) semimetallic state. The structure of\nTCH-SSH-2D is derived from the TCH-type Archimedean polyhedral carbon cluster\nunits, combined with the SSH lattice model, possessing a space group of\ntetragonal P4/mmm. Using first-principles calculations, we demonstrate that the\nsystem is dynamically, thermodynamically, and mechanically stable. It exhibits\nan energetically favorable structure with no imaginary frequency in the phonon\ndispersion curves and elastic constants satisfying the Born-Huang stability\ncriterion. Our findings not only contribute to a deeper understanding of the\ncarbon allotrope family but also provide an opportunity to explore unique Dirac\nstates in two-dimensional pure carbon systems."
    },
    {
        "anchor": "Elimination of the linearization error and improved basis-set\n  convergence within the FLAPW method: We analyze in detail the error that arises from the linearization in\nlinearized augmented-plane-wave (LAPW) basis functions around predetermined\nenergies $E_l$ and show that it can lead to undesirable dependences of the\ncalculated results on method-inherent parameters such as energy parameters\n$E_l$ and muffin-tin sphere radii. To overcome these dependences, we evaluate\napproaches that eliminate the linearization error systematically by adding\nlocal orbitals (LOs) to the basis set. We consider two kinds of LOs: (i)\nconstructed from solutions $u_l(r,E)$ to the scalar-relativistic approximation\nof the radial Dirac equation with $E>E_l$ and (ii) constructed from second\nenergy derivatives $\\partial^2 u_l(r,E) / \\partial E^2$ at $E=E_l$. We find\nthat the latter eliminates the error most efficiently and yields the density\nfunctional answer to many electronic and materials properties with very high\nprecision. Finally, we demonstrate that the so constructed LAPW+LO basis shows\na more favorable convergence behavior than the conventional LAPW basis due to a\nbetter decoupling of muffin-tin and interstitial regions, similarly to the\nrelated APW+lo approach, which requires an extra set of LOs to reach the same\ntotal energy, though.",
        "positive": "The effect of stripe domain structure on dynamic permeability of thin\n  ferromagnetic films with out-of-plane uniaxial anisotropy: The permeability is calculated for a thin ferromagnetic film with the stripe\ndomain structure and out-of-plane uniaxial magnetic anisotropy. Analytical\nexpressions for the frequency dependence of components of permeability tensor\nare derived with the use of the Smit-Beljers method, with the thickness of\ndomain walls and the domain wall motion being neglected. The effect of the\ndomain width and the angle between the anisotropy axis and the film plane on\nthe frequency dependence of the permeability is analyzed. General equations\nrelating the static permeability components and the ferromagnetic resonance\nfrequencies are found. The results of the approach are applied to the\nderivation of the constraint for the microwave permeability of thin\nferromagnetic films. The analysis of the constraint as a function of the axis\ndeviation angle, the domain aspect ratio and the damping parameter allows the\nconditions to be found for maximal microwave permeability. The results obtained\nmay be useful in connection with the problem of developing high-permeable\nmicrowave magnetic materials."
    },
    {
        "anchor": "Rubber friction on wet and dry road surfaces: the sealing effect: Rubber friction on wet rough substrates at low velocities is typically 20-30%\nsmaller than for the corresponding dry surfaces. We show that this cannot be\ndue to hydrodynamics and propose a novel explanation based on a sealing effect\nexerted by rubber on substrate \"pools\" filled with water. Water effectively\nsmoothens the substrate, reducing the major friction contribution due to\ninduced viscoelastic deformations of the rubber by surface asperities. The\ntheory is illustrated with applications related to tire-road friction.",
        "positive": "An XMCD study of magnetism and valence state in iron-substituted\n  strontium titanate: Room temperature ferromagnetism was characterized for thin films of\nSrTi$_{0.6}$Fe$_{0.4}$O$_{3-{\\delta}}$ grown by pulsed laser deposition on\nSrTiO$_{3}$ and Si substrates under different oxygen pressures and after\nannealing under oxygen and vacuum conditions. X-ray magnetic circular dichroism\ndemonstrated that the magnetization originated from Fe$^{2+}$ cations, whereas\nFe$^{3+}$ and Ti$^{4+}$ did not contribute. Films with the highest magnetic\nmoment (0.8 {\\mu}B per Fe) had the highest measured Fe$^{2+}$:Fe${^3+}$ ratio\nof 0.1 corresponding to the largest concentration of oxygen vacancies ({\\delta}\n= 0.19). Post-growth annealing treatments under oxidizing and reducing\nconditions demonstrated quenching and partial recovery of magnetism\nrespectively, and a change in Fe valence states. The study elucidates the\nmicroscopic origin of magnetism in highly Fe-substituted\nSrTi$_{1-x}$Fe$_x$O$_{3-{\\delta}}$ perovskite oxides and demonstrates that the\nmagnetic moment, which correlates with the relative content of Fe$^{2+}$ and\nFe$^{3+}$, can be controlled via the oxygen content, either during growth or by\npost-growth annealing."
    },
    {
        "anchor": "Giant optical birefringence of semiconductor nanowire metamaterials: Semiconductor nanowires exhibit large polarization anisotropy for the\nabsorption and emission of light, making them ideal building blocks for novel\nphotonic metamaterials. Here, we demonstrate that a high density of aligned\nnanowires exhibits giant optical birefringence, a collective phenomenon\nobservable uniquely for collections of wires. The nanowire material was grown\non gallium phosphide (GaP) (111) in the form of vertically standing GaP\nnanowires. We obtain the largest optical birefringence to date, with a\ndifference between the in-plane and out-of-plane refractive indices of 0.80 and\na relative birefringence of 43%. These values exceed by a factor of 75 the\nnatural birefringence of quartz and a by more than a factor of two the highest\nvalues reported so far in other artificial materials. By exploiting the\nspecific crystallographic growth directions of the nanowires on the substrate,\nwe further demonstrate full control over the orientation of the optical\nbirefringence effect in the metamaterial.",
        "positive": "Strong spin-Hall and Nernst effects in a p-band semimetal: Since spin currents can be generated, detected, and manipulated via the spin\nHall effect (SHE), the design of strong SHE materials has become a focus in the\nfield of spintronics. Because of the recent experimental progress also the spin\nNernst effect (SNE), the thermoelectrical counterpart of the SHE, has attracted\nmuch interest. Empirically strong SHEs and SNEs are associated with $d$-band\ncompounds, such as transition metals and their alloys -- the largest spin Hall\nconductivity (SHC) in a $p$-band material is $\\sim 450$\n$\\left(\\hbar/e\\right)\\left(\\Omega\\cdot cm\\right)^{-1}$ for a Bi-Sb alloy, which\nis only about a fifth of platinum. This raises the question whether either the\nSHE and SNE are naturally suppressed in $p$-bands compounds, or favourable\n$p$-band systems were just not identified yet. Here we consider the $p$-band\nsemimetal InBi, and predict it has a record SHC $\\sigma_{xy}^{z}\\approx 1100 \\\n\\left(\\hbar/e\\right)\\left(\\Omega\\cdot cm\\right)^{-1}$ which is due to the\npresence of nodal-lines in its band structure. Also the spin-Nernst\nconductivity $\\alpha_{zx}^y\\approx 1.2 \\ (\\hbar/e)(A/m\\cdot K)$ is very large,\nbut our analysis shows its origin is different as the maximum appears in a\ndifferent tensor element. This insight gained on InBi provides guiding\nprinciples to obtain a strong SHE and SNE in $p$-band materials and establishes\na more comprehensive understanding of the relationship between the SHE and SNE."
    },
    {
        "anchor": "Analytical Study of Thermal Annealing Behaviour of Erbium Emission in\n  Er2O3-Sol-Gel Silica Films: Room-temperature 1535-nm-band photoluminescence in ~126 nm silica films (6\nat. % doping), produced by spin-coating an Er2O3 and tetraethylorthosilicate\nsol-gel formulation on silicon substrates, was studied as a function of vacuum\nfurnace annealing (500 to 1050 degrees C). Emission is strongly enhanced for\nannealing near 850 degrees C, which is shown by modeling the temperature\ndependence as arising from thermally-activated removal of hydroxyl ions.\nSuitability of such a process for silicon-based applications is discussed.",
        "positive": "Hidden wallpaper fermion and third-order topological insulator: Nonsymmorphic symmetry can induce exotic wallpaper fermions, e.g., hourglass\nfermion, fourfold-degenerate Dirac fermion, and M\\\"obius fermion, as commonly\nbelieved only in nonsymmorphic wallpaper groups. Here, we extend the notion of\nwallpaper fermions to symmorphic wallpaper groups, and remarkably uncover the\nemergence of long-awaited third-order topological insulators. The symmetry\nanalysis and k $\\cdot$ p models reveal that nonessential symmetries play an\nessential role for obtaining the previously overlooked hidden surface spectrum.\nBased on this, we present the hourglass fermion, fourfold-degenerate Dirac\nfermion, and M\\\"obius fermion in the (001) surface of Tl$_4$XTe$_3$ (X = Pb/Sn)\nwith a symmorphic wallpaper group $p4m$. Remarkably, 16 helical corner states\nreside on eight corners in Kramers pair, rendering the first real electronic\nmaterial of third-order topological insulator. A time-reversal polarized\noctupole polarization is defined to uncover the nontrivial third-order\ntopology, as is implemented by the 2$^{nd}$ and 3$^{rd}$ order Wilson loop\ncalculations. Our results could considerably broaden the range of wallpaper\nfermions and lay the foundation for future experimental investigations of\nthird-order topological insulators."
    },
    {
        "anchor": "Statistical Mechanics of the Glass Transition in One-Component Liquids\n  with Anisotropic Potential: We study a recently introduced model of one-component glass-forming liquids\nwhose constituents interact with anisotropic potential. This system is\ninteresting per-se and as a model of liquids like glycerol (interacting via\nhydrogen bonds) which are excellent glass formers. We work out the statistical\nmechanics of this system, encoding the liquid and glass disorder using\nappropriate quasi-particles (36 of them). The theory provides a full\nexplanation of the glass transition phenomenology, including the identification\nof a diverging length scale and a relation between the structural changes and\nthe diverging relaxation times.",
        "positive": "Universal polarization energies for defects in monolayer, surface and\n  bulk hexagonal boron nitride : A finite-size fragments GW approach: We study defect energy levels in hexagonal boron-nitride with varying number\nof layers using a fragment many-body $GW$ formalism, taking as examples the\nparadigmatic carbon-dimer and $C_BV_N$ defects. We show that a single layer can\nbe fragmented in polarizable finite-size areas reproducing faithfully the\neffect of the dielectric environment, dramatically facilitating the study at\nthe many-body level of point defects in the dilute limit. The evolution of\ndefect energy levels from the monolayer to a $n$-layer system due to increased\nscreening, labeled polarization energies, follow a simple $({\\Delta P}/n +\nP_{\\infty})$ behavior. The coefficients $\\Delta P$ and $P_{\\infty}$ are found\nto be close-to-universal, with opposite signs for holes and electrons,\ncharacterizing mainly the host and the position of the defect (surface or\nbulk), but hardly the defect type. Our results rationalize the evolution of\ndefect energy levels with layers number, allowing to safely extrapolate results\nobtained for the monolayer to few-layers, surface or bulk \\textit{h}-BN. The\npresent many-body fragment approach further opens the door to studying\ndisordered 2D layers."
    },
    {
        "anchor": "Single layer of MX3 (M=Ti, Zr; X=S, Se, Te): a new platform for\n  nano-electronics and optics: A serial of two dimensional titanium and zirconium trichalcogenides\nnanosheets MX3 (M=Ti, Zr; X=S, Se, Te) are investigated based on\nfirst-principles calculations. The evaluated low cleavage energy indicates that\nstable two dimensional monolayers can be exfoliated from their bulk crystals in\nexperiment. Electronic studies reveal very rich electronic properties in these\nmonolayers, including metallic TiTe3 and ZrTe3, direct band gap semiconductor\nTiS3 and indirect band gap semiconductors TiSe3, ZrS3 and ZrSe3. The band gaps\nof all the semiconductors are between 0.57~1.90 eV, which implies their\npotential applications in nano-electronics. And the calculated effective masses\ndemonstrate highly anisotropic conduction properties for all the\nsemiconductors. Optically, TiS3 and TiSe3 monolayers exhibit good light\nabsorption in the visible and near-infrared region respectively, indicating\ntheir potential applications in optical devices. In particular, the highly\nanisotropic optical absorption of TiS3 monolayer suggests it could be used in\ndesigning nano optical waveguide polarizers.",
        "positive": "Modified Becke-Johnson potential investigation of half-metallic Heusler\n  compounds: We have investigated the electronic structures of various potentially\nhalf-metallic Heusler compounds with the Tran-Blaha modified Becke-Johnson\n(TB-mBJLDA) potential within the density functional theory. The half-metallic\ngaps are considerably enhanced with respect to values from the\nPerdew-Burke-Ernzerhof (PBE) functional. In particular the unoccupied densities\nof states are modified by mBJLDA, and agreement with experiment is considerably\nworse than for PBE. The agreement of the densities of states can be improved by\nreducing the Tran-Blaha parameter c. However, ground state properties such as\nthe hyperfine fields are more accurately described by PBE than by mBJLDA.\nDespite its success for ionic and covalent semiconductors and insulators, we\nconclude that mBJLDA is not a suitable approximation for half-metallic Heusler\ncompounds."
    },
    {
        "anchor": "Anomalous Hall magnetoresistance in a ferromagnet: The anomalous Hall effect, observed in conducting ferromagnets with broken\ntime-reversal symmetry, offers the possibility to couple spin and orbital\ndegrees of freedom of electrons in ferromagnets. In addition to charge, the\nanomalous Hall effect also leads to spin accumulation at the surfaces\nperpendicular to both the current and magnetization direction. Here we\nexperimentally demonstrate that the spin accumulation, subsequent spin\nbackflow, and spin-charge conversion can give rise to a different type of spin\ncurrent related magnetoresistance, dubbed here as the anomalous Hall\nmagnetoresistance, which has the same angular dependence as the recently\ndiscovered spin Hall magnetoresistance. The anomalous Hall magnetoresistance is\nobserved in four types of samples: co-sputtered (Fe1-xMnx)0.6Pt0.4, Fe1-xMnx\nand Pt multilayer, Fe1-xMnx with x = 0.17 to 0.65 and Fe, and analyzed using\nthe drift-diffusion model. Our results provide an alternative route to study\ncharge-spin conversion in ferromagnets and to exploit it for potential\nspintronic applications.",
        "positive": "Ultrafast light-induced magnetization in non-magnetic films: from\n  orbital and spin Hall phenomena to the inverse Faraday effect: The field of orbitronics has emerged with great potential to impact\ninformation technology by enabling environmentally friendly electronic devices.\nThe main electronic degree of freedom at play is the orbital angular momentum,\nwhich can give rise to a myriad of phenomena such as the orbital Hall effect\n(OHE), torques and orbital magnetoelectric effects. Here, we explore via\nrealistic time-dependent electronic structure simulations the magnetic response\nof a non-magnetic material, an ultrathin Pt film, to ultrafast laser pulses of\ndifferent polarizatons and helicities. We demonstrate the generation of\nsignificant orbital and spin magnetizations and identify the underlying\nmechanisms consisting of the interplay of the OHE, inverse Faraday effect and\nspin-orbit interaction. Our discoveries advocate for the prospect of encoding\nmagnetic information using light in materials that are not inherently magnetic."
    },
    {
        "anchor": "Giant Rashba effect at the topological surface of PrGe revealing\n  antiferromagnetic spintronics: Rashba spin-orbit splitting in the magnetic materials opens up a new\nperspective in the field of spintronics. Here, we report a giant Rashba-type\nspin-orbit effect on PrGe [010] surface in the paramagnetic phase with Rashba\ncoefficient {\\alpha}_R=5 eV{\\AA}. Significant changes in the electronic band\nstructure has been observed across the phase transitions from paramagnetic to\nantiferromagnetic (44 K) and from antiferromagnetic to the ferromagnetic ground\nstate (41.5 K). We find that Pr 4f states in PrGe is strongly hybridized with\nthe Pr 5d and Ge 4s-4p states near the Fermi level. The behavior of Rashba\neffect is found to be different in the k_x and the k_y directions showing\nelectron-like and the hole-like bands, respectively. The possible origin of\nRashba effect in the paramagnetic phase is related to the anti-parallel spin\npolarization present in this system. First-principles density functional\ncalculations of Pr terminated surface with the anti-parallel spins shows a fair\nagreement with the experimental results. We find that the anti-parallel spins\nare strongly coupled to the lattice such that the PrGe system behaves like weak\nferromagnetic system. Analysis of the energy dispersion curves at different\nmagnetic phases showed that there is a competition between the\nDzyaloshinsky-Moriya interaction and the exchange interaction which gives rise\nto the magnetic ordering in PrGe. Supporting evidences of the presence of\nDzyaloshinsky-Moriya interaction are observed as anisotropic magnetoresistance\nwith respect to field direction and first-order type hysteresis in the X-ray\ndiffraction measurements. A giant negative magnetoresistance of 43% in the\nantiferromagnetic phase and tunable Rashba parameter with temperature across\nthe magnetic transitions makes this material a suitable candidate for\ntechnological application in the antiferromagnetic spintronic devices.",
        "positive": "Robust topological surface states of Bi2Se3 thin films on amorphous\n  SiO2/Si substrate and a large ambipolar gating effect: The recent emergence of topological insulators (TI) has spurred intensive\nefforts to grow TI thin films on various substrates. However, little is known\nabout how robust the topological surface states (TSS) are against disorders and\nother detrimental effects originating from the substrates. Here, we report\nobservation of a well-defined TSS on Bi2Se3 films grown on amorphous SiO2\n(a-SiO2) substrates and a large gating effect on these films using the\nunderneath doped-Si substrate as the back gate. The films on a-SiO2 were\ncomposed of c-axis ordered but random in-plane domains. However, despite the\nin-plane randomness induced by the amorphous substrate, the transport\nproperties of these films were superior to those of similar films grown on\nsingle-crystalline Si(111) substrates, which are structurally better matched\nbut chemically reactive with the films. This work sheds light on the importance\nof chemical compatibility, compared to lattice matching, for the growth of TI\nthin films, and also demonstrates that the technologically-important and\ngatable a-SiO2/Si substrate is a promising platform for TI films."
    },
    {
        "anchor": "Core Electron Binding Energies in Solids from Periodic All-Electron\n  $\u0394$-Self-Consistent-Field Calculations: Theoretical calculations of core electron binding energies are important for\naiding the interpretation of experimental core level photoelectron spectra. In\nprevious work, the $\\Delta$-Self-Consistent-Field ($\\Delta$-SCF) method based\non density functional theory has been shown to yield highly accurate 1s and 2p\nbinding energies in free molecules. However, most experimental work is\nconcerned with solids, not gases. In this study, we demonstrate the application\nof the all-electron $\\Delta$-SCF method to periodic systems. A consideration of\nthe experimentally accessible points of reference leads to the definition of a\ncore electron binding energy in a solid as the difference between the total\nenergies of two $N-1$ electron systems: one with an explicit, localized core\nhole, and one with an electron removed from the highest occupied state. The\ncalculation of each of these quantities is addressed. In addition, the analogy\nbetween a localized core hole and a charged defect in a solid is highlighted,\nand the extrapolation of calculated core electron binding energies to the\ninfinite supercell limit is discussed. It is found that the extrapolated values\nof the core electron binding energies from periodic $\\Delta$-SCF calculations\nagree well with experimental results for both metallic and insulating systems,\nwith a mean absolute error of 0.24 eV for the 15 core levels considered in this\nstudy.",
        "positive": "Magnetic Modulation in Mechanical Alloyed Cr1.4fe0.6o3 Oxide: We have synthesized Cr1.4Fe0.6O3 compound through mechanical alloying of\nCr2O3 and Fe2O3 powders and subsequent thermal annealing. The XRD spectrum, SEM\npicture and microanalysis of EDAX spectrum have been used to understand the\nstructural evolution in the alloyed compound. The alloyed samples are matching\nto rhombohedral structure with R3C space group. The observation of a modulated\nmagnetic order confirmed a systematic diffusion of Fe atoms into the Cr sites\nof lattice structure. A field induced magnetic behaviour is seen in the field\ndependence of magnetization data of the annealed samples. The behaviour is\nsignificantly different from the mechanical alloyed samples. The experimental\nresults provided the indications of considering the present material as a\npotential candidate for opto-electronic applications."
    },
    {
        "anchor": "Properties and influence of microstructure and crystal defects in\n  Fe$_2$VAl modified by laser surface remelting: Laser surface remelting can be used to manipulate the microstructure of cast\nmaterial. Here, we present a detailed analysis of the microstructure of\nFe$_2$VAl following laser surface remelting. Within the melt pool, elongated\ngrains grow nearly epitaxially from the heat-affected zone. These grains are\nseparated by low-angle grain boundaries with 1{\\deg}-5{\\deg} misorientations.\nSegregation of vanadium, carbon, and nitrogen at grain boundaries and\ndislocations is observed using atom probe tomography. The local electrical\nresistivity was measured by an in-situ four-point-probe technique. A smaller\nincrease in electrical resistivity is observed at these low-angle grain\nboundaries compared to high-angle grain boundaries in a cast sample. This\nindicates that grain boundary engineering could potentially be used to\nmanipulate thermoelectric properties.",
        "positive": "Machine learning of twin/matrix interfaces from local stress field: Twinning is an important deformation mode in plastically deformed hexagonal\nclose-packed materials. The extremely high twin growth rates at the nanoscale\nmake atomistic simulations an attractive method for investigating the role of\nindividual twin/matrix interfaces such as twin boundaries and basal-prismatic\ninterfaces in twin growth kinetics. Unfortunately, there is no single framework\nthat allows researchers to differentiate such interfaces automatically, neither\nin experimental in-situ transmission electron microscopy analysis images nor in\natomistic simulations. Moreover, the presence of alloying elements introduces\nsubstantial noise to local atomic environments, making it nearly impossible to\nidentify which atoms belong to which interface. Here, with the help of advanced\nmachine learning methods, we provide a proof-of-concept way of using the local\nstress field distribution as an indicator for the presence of interfaces and\nfor determining their types. We apply such an analysis to the growth of twin\nembryos in Mg-10 at.% Al alloys under constant stress and constant strain\nconditions, corresponding to two extremes of high and low strain rates,\nrespectively. We discover that the kinetics of such growth is driven by\nhigh-energy basal-prismatic interfaces, in line with our experimental\nobservations for pure Mg."
    },
    {
        "anchor": "Exchange torque in noncollinear spin density functional theory with a\n  semilocal exchange functional: We present a semilocal exchange-correlation energy functional for\nnoncollinear spin density functional theory based on short-range expansions of\nthe spin-resolved exchange hole and the two-body density matrix. Our functional\nis explicitly derived for noncollinear magnetism, U(1) and SU(2) gauge\ninvariant, and gives rise to nonvanishing exchange-correlation torques. Testing\nthe functional for frustrated antiferromagnetic chromium clusters, the exchange\npart is shown to perform favorably compared to the far more expensive Slater\nand optimized effective potentials, and a delicate interplay between exchange\nand correlation torques is uncovered.",
        "positive": "Landau-Lifshitz-Bloch equation for ferrimagnets with higher-order\n  interaction: We present a micromagnetic formulation for modeling the magnetization\ndynamics and thermal equilibrium in ferrimagnetic materials at low and elevated\ntemperatures. The formulation is based on a mean field approximation (MFA). In\nthis formulation, the ferrimagnet is described micromagnetically by two coupled\nsublattices with corresponding interactions, including inter- and\nintra-sublattice micromagnetic exchange as well as four-spin interactions\ndescribed as an inter-sublattice molecular field with a cubic dependence of the\nmagnetization. The MFA is used to derive a Landau Lifshitz Bloch type equation\nfor ferrimagnetic material, including cases with a ferromagnetic -\nantiferromagnetic phase transitions. For validation, the results obtained via\nthe presented model are compared with recent experimental data for phase\ntransitions in FeRh."
    },
    {
        "anchor": "Over the shear paradigm: Deformation twinning and martensitic transformations are displacive\ntransformations; they are defined by high speed collective displacements of the\natoms, the existence of a parent/daughter orientation relationship, and plate\nor lath morphologies. The current crystallographic models of deformation\ntwinning in metals are based on the 150 year-old concept of simple shear. For\nmartensitic transformations, a generalized version of simple shear called\ninvariant plane strain takes into account the volume change; it is associated\nwith one or two simple shears in the phenomenological theory of martensitic\ncrystallography built more than 60 years ago. As simple shears would involve\nunrealistic stresses, dislocation/disconnection-mediated versions of the usual\ncrystallographic models of displacive transformations have been developed over\nthe last decades. However, fundamental questions remain unsolved. How do the\natoms move? How could dislocations be created and propagate in a coordinated\nway at the speed of sound? In order to solve these issues an approach that is\nnot based on simple shear nor on dislocation/disconnection has been applied to\ndifferent displacive transformations over the last years. It assumes that the\natoms are hard-spheres, which permits for any specific orientation relationship\nto determine the atomics trajectories, the lattice distortion and shuffling (if\nrequired) as analytical functions of a unique angular parameter. The aim of the\npresent paper is to give a brief historical review of the current models based\non the shear concept and of their dislocation-mediated versions, and to\nintroduce the new paradigm of angular distortion. Examples will be taken by\nusing some recent publications. The possibilities offers by this approach in\nmechanics and thermodynamics are briefly discussed.",
        "positive": "A Methodology to Determine Tooling Interface Temperature and Traction\n  Conditions from Measured Force and Torque in Materials Processing Simulations\n  Based on Multimesh Error Estimation: A methodology is presented for estimating average values for the temperature\nand the frictional traction over a tool-workpiece interface using measured\nvalues of force and torque applied to the tool. The approach was developed\nspecifically for friction stir welding and friction stir processing\napplications, but is sufficiently general to be of use in a variety of other\nprocesses that involve sliding contact and heating at a tool-workpiece\ninterface. The methodology works with a finite element framework that is\nintended to predict the evolution of the microstructural state of the workpiece\nmaterial as it undergoes a complex thermomechanical history imposed by the\nprocess tooling. We employ a three-dimensional, Eulerian, finite element\nformulation; it includes coupling among the solutions for velocity, temperature\nand material state evolution. A critical element of the methodology is a\nprocedure to estimate the tool interface traction and temperature from typical,\nmeasured values of force and torque. The procedure leads naturally to an\nintuitive basis for estimating error that is used in conjunction with multiple\nmeshes to assure convergence. The methodology is demonstrate for a suite of\nthree experiments that had been previously published as part of a study on the\neffect of weld speed on friction stir welding. The probe interface temperatures\nand torques are estimated for all three weld speeds and the multi-mesh error\nestimation methodology is employed to quantify the rate of convergence.\nFinally, comparison of computed and measured power usage is used as a further\nvalidation. Using the converged results, trends in the material flow,\ntemperature, stress, deformation rate and material state with changing weld\nconditions are examined."
    },
    {
        "anchor": "Carbon-Rich Carbon Nitride Monolayers with Dirac Cones: Dumbbell C4N: Two-dimensional (2D) carbon nitride materials play an important role in\nenergy-harvesting, energy-storage and environmental applications. Recently, a\nnew carbon nitride, 2D polyaniline (C3N) was proposed [PNAS 113 (2016)\n7414-7419]. Based on the structure model of this C3N monolayer, we propose two\nnew carbon nitride monolayers, named dumbbell (DB) C4N-I and C4N-II. Using\nfirst-principles calculations, we systematically study the structure,\nstability, and band structure of these two materials. In contrast to other\ncarbon nitride monolayers, the orbital hybridization of the C/N atoms in the DB\nC4N monolayers is sp3. Remarkably, the band structures of the two DB C4N\nmonolayers have a Dirac cone at the K point and their Fermi velocities are\ncomparable to that of graphene. This makes them promising materials for\napplications in high-speed electronic devices. Using a tight-binding model, we\nexplain the origin of the Dirac cone.",
        "positive": "Ab initio study on the magneto-structural properties of MnAs: The magnetic and structural properties of MnAs are studied with ab initio\nmethods, and by mapping total energies onto a Heisenberg model. The stability\nof the different phases is found to depend mainly on the volume and on the\namount of magnetic order, confirming previous experimental findings and\nphenomenological models. It is generally found that for large lattice constants\nthe ferromagnetic state is favored, whereas for small lattice constants\ndifferent antiferromagnetic states can be stabilized. In the ferromagnetic\nstate the structure with minimal energy is always hexagonal, whereas it becomes\northorhombically distorted if there is an antiferromagnetic component in the\nhexagonal plane. For the paramagnetic state the stable cell is found to be\northorhombic up to a critical lattice constant of about 3.7 Angstrom, above\nwhich it remains hexagonal. This leads to the second order structural phase\ntransition between paramagnetic states at about 400 K, where the lattice\nparameter increases above this critical value with rising temperature due to\nthe thermal expansion. For the paramagnetic state an analytic approximation for\nthe magnitude of the orthorhombic distortion as a function of the lattice\nconstant is given. Within the mean field approximation the dependence of the\nCurie temperature on the volume and on the orthorhombic distortion is\ncalculated. For orthorhombically distorted cells the Curie temperature is much\nsmaller than for hexagonal cells. This is mainly due to the fact that some of\nthe exchange coupling constants in the hexagonal plane become negative for\ndistorted cells. With these results a description of the susceptibility as\nfunction of temperature is given."
    },
    {
        "anchor": "Orientational interaction and ordering of Cd_4 tetrahedra in a\n  quasicrystal approximant: We model the quasicrystal-related structure CaCd$_6$, a bcc packing of\nicosahedral clusters containing tetrahedra which undergo orientational\norderings at T<100 K. We use general schemes to evaluate an effective\nHamltonian for inter-tetrahedron orientations, based on all-atom relaxations,\neither in terms of discrete cluster orientations, or of continuous rotation\nangles. The effective Hamiltonian is used in Monte Carlo simulations to find\nthe (complex) ground state ordering pattern as a function of pressure. A\npreliminary investigation of thermal transitions found (in part of the pressure\nrange) two different first-order transitions occurring below 100 K.",
        "positive": "Pressurizing Field-Effect Transistors of Few-Layer MoS2 in a Diamond\n  Anvil Cell: Hydrostatic pressure applied using diamond anvil cells (DAC) has been widely\nexplored to modulate physical properties of materials by tuning their lattice\ndegree of freedom. Independently, electrical field is able to tune the\nelectronic degree of freedom of functional materials via, for example, the\nfield-effect transistor (FET) configuration. Combining these two orthogonal\napproaches would allow discovery of new physical properties and phases going\nbeyond the known phase space. Such experiments are, however, technically\nchallenging and have not been demonstrated. Herein, we report a feasible\nstrategy to prepare and measure FETs in a DAC by lithographically patterning\nthe nanodevices onto the diamond culet. Multiple-terminal FETs were fabricated\nin the DAC using few-layer MoS2 and BN as the channel semiconductor and\ndielectric layer, respectively. It is found that the mobility, conductance,\ncarrier concentration, and contact conductance of MoS2 can all be significantly\nenhanced with pressure. We expect that the approach could enable unprecedented\nways to explore new phases and properties of materials under coupled\nmechano-electrostatic modulation."
    },
    {
        "anchor": "Vibrational Dynamics within the Embedded-Atom-Method Formalism and the\n  Relationship to Born-von-K\u00e1rm\u00e1n Force Constants: We derive expressions for the dynamical matrix of a crystalline solid with\ntotal potential energy described by an embedded-atom-method (EAM) potential. We\nmake no assumptions regarding the number of atoms per unit cell. These\nequations can be used for calculating both bulk phonon modes as well the modes\nof a slab of material, which is useful for the study of surface phonons. We\nfurther discuss simplifications that occur in cubic lattices with one atom per\nunit cell. The relationship of Born-von-K\\'arm\\'an (BvK) force constants -\nwhich are readily extracted from experimental vibrational dispersion curves -\nto the EAM potential energy is discussed. In particular, we derive equations\nfor BvK force constants for bcc and fcc lattices in terms of the functions that\ndefine an EAM model. The EAM - BvK relationship is useful for assessing the\nsuitability of a particular EAM potential for describing vibrational spectra,\nwhich we illustrate using vibrational data from the bcc metals K and Fe and the\nfcc metal Au.",
        "positive": "Correlation between microstructure deflections and film/substrate\n  curvature under generalized stress fields: In this article we develop an analytical theory that correlates the\nmacroscopic curvature of stressed film/substrate systems with the microscopic\nin-plane and out-of-plane deflections of planar rotators. Extending this\nstress-deflection relations in the case of nonlinear stress fields and\nvalidating the results with the aid of finite element simulations. We use this\ntheory to study the heteroepitaxial growth of cubic silicon carbide on silicon\n(100) and discover that due, to defects generated on the silicon substrate\nduring the carbonization process, wafer curvature techniques may not allow the\ndetermination of the stress field in the grown films either quantitatively or\nqualitatively."
    },
    {
        "anchor": "Colossal dielectric constants in single-crystalline and ceramic\n  CaCu3Ti4O12 investigated by broadband dielectric spectroscopy: In the present work the authors report results of broadband dielectric\nspectroscopy on various samples of CaCu3Ti4O12, including so far only rarely\ninvestigated single crystalline material. The measurements extend up to 1.3\nGHz, covering more than nine frequency decades. We address the question of the\norigin of the colossal dielectric constants and of the relaxational behavior in\nthis material, including the second relaxation reported in several recent\nworks. For this purpose, the dependence of the temperature- and\nfrequency-dependent dielectric properties on different tempering and surface\ntreatments of the samples and on ac-field amplitude are investigated. Broadband\nspectra of a single crystal are analyzed by an equivalent circuit description,\nassuming two highly resistive layers in series to the bulk. Good fits could be\nachieved, including the second relaxation, which also shows up in single\ncrystals. The temperature- and frequency-dependent intrinsic conductivity of\nCCTO is consistent with the Variable Range Hopping model. The second relaxation\nis sensitive to surface treatment and, in contrast to the main relaxation, also\nis strongly affected by the applied ac voltage. Concerning the origin of the\ntwo insulating layers, we discuss a completely surface-related mechanism\nassuming the formation of a metal-insulator diode and a combination of surface\nand internal barriers.",
        "positive": "Mechanical force involved multiple fields switching of both local\n  ferroelectric and magnetic domain in a Bi5Ti3FeO15 thin film: Multiferroics have received intense attention due to their great application\npotential in multi-state information storage devices and new types of sensors.\nCoupling among ferroic orders such as ferroelectricity, (anti-)ferromagnetism,\nferroelasticity, etc. will enable dynamic interaction between these ordering\nparameters. Direct visualization of such coupling behaviour in single phase\nmultiferroic materials is highly desirable for both applications and\nfundamental study. Manipulation of both ferroelectric and magnetic domains of\nBi5Ti3FeO15 thin film using electric field and external mechanical force is\nreported, which confirms the magnetoelectric coupling in Bi5Ti3FeO15, indicates\nthe electric and magnetic orders are coupled through ferroelasticity. Due to\nthe anisotropic relaxation of ferroelastic strain, the back-switching of\nout-of-plane electric domains is not as obvious as in-plane. An inevitable\ndestabilization of the coupling between elastic and magnetic ordering happens\nbecause of the elastic strain relaxation, which result in a subsequent decay of\nmagnetic domain switching. Mechanical force applied on the surface of\nBi5Ti3FeO15 film generates by an AFM tip will effectively drive a transition of\nthe local ferroelastic strain state, reverse both the polarization and\nmagnetization in a way similar to an electric field. Current work provides a\nframework for exploring cross-coupling among multiple orders and potential for\ndeveloping novel nanoscale functional devices."
    },
    {
        "anchor": "Pore morphology evolution and atom distribution of doped Fe2O3 foams\n  developed by freeze-casting after redox cycling: Chemical looping water splitting systems operate at relatively high\ntemperatures (450-800 degree C) to produce, purify, or store hydrogen by the\ncyclic reduction and oxidation (redox) of a solid oxygen carrier. Therefore, to\nimprove long-term operation, it is necessary to develop highly stable oxygen\ncarriers with large specific surface areas. In this work, highly interconnected\ndoped Fe2O3 foams are fabricated through the freeze-casting technique, and the\naid of a submicrometric camphene-based suspension to prevent Fe sintering and\npore clogging during redox operation. The influence of the dopant elements (Al\nand Ce) over the pore morphology evolution, and redox performances are\nexamined. The use of an Fe2O3 porous structure with initial pore size above 100\nmicrons shows a significant reduction of the sample densification, and the\naddition of Al2O3 by the co-precipitation process proves to be beneficial in\npreventing the generation of a core-shell structure following redox processing.",
        "positive": "Coherent manipulation of magnetization precession in ferromagnetic\n  semiconductor (Ga,Mn)As with successive optical pumping: We report dynamic control of magnetization precession by light alone. A\nferromagnetic (Ga,Mn)As epilayer was used for experiments. Amplitude of\nprecession was modulated to a large extent by tuning the time interval between\ntwo successive optical pump pulses which induced torques on magnetization\nthrough a non-thermal process. Nonlinear effect in precession motion was also\ndiscussed."
    },
    {
        "anchor": "Increased material differentiation through multi-contrast x-ray imaging:\n  a preliminary evaluation of potential applications to the detection of threat\n  materials: Most material discrimination in security inspections is based on dual-energy\nx-ray imaging, which enables the determination of a material's effective atomic\nnumber (Zeff) as well as electron density and its consequent classification as\norganic or inorganic. Recently phase-based \"dark-field\" x-ray imaging\napproaches have emerged that are sensitive to complementary features of a\nmaterial, namely its unresolved microstructure. It can therefore be speculated\nthat their inclusion in the security-based imaging could enhance material\ndiscrimination, for example of materials with similar electron densities and Z\neff but different microstructures. In this paper, we present a preliminary\nevaluation of the advantages that such a combination could bear. Utilising an\nenergy-resolved detector for a phase-based dark-field technique provides\ndual-energy attenuation and dark-field images simultaneously. In addition,\nsince we use a method based on attenuating x-ray masks to generate the\ndark-field images, a fifth (attenuation) image at a much higher photon energy\nis obtained by exploiting the x-rays transmitted through the highly absorbing\nmask septa. In a first test, a threat material is imaged against a non-threat\none, and we show how their discrimination based on maximising their relative\ncontrast through linear combinations of two and five imaging channels leads to\nan improvement in the latter case. We then present a second example to show how\nthe method can be extended to discrimination against more than one non-threat\nmaterial, obtaining similar results. Albeit admittedly preliminary, these\nresults indicate that significant margins of improvement in material\ndiscrimination are available by including additional x-ray contrasts in the\nscanning process.",
        "positive": "First principle study of the thermal conductance in graphene nanoribbon\n  with vacancy and substitutional silicon defect: The thermal conductance in graphene nanoribbon with a vacancy or silicon\npoint defect (substitution of C by Si atom) is investigated by non-equilibrium\nGreen's function (NEGF) formalism combined with first-principle calculations\ndensity-functional theory with local density approximation. An efficient\ncorrection to the force constant matrix is presented to solve the conflict\nbetween the long-range character of the {\\it ab initio} approach and the\nfirst-nearest-neighboring character of the NEGF scheme. In nanoribbon with a\nvacancy defect, the thermal conductance is very sensitive to the position of\nthe vacancy defect. A vacancy defect situated at the center of the nanoribbon\ngenerates a saddle-like surface, which greatly reduces the thermal conductance\nby strong scattering to all phonon modes; while an edge vacancy defect only\nresults in a further reconstruction of the edge and slightly reduces the\nthermal conductance. For the Si defect, the position of the defect plays no\nrole for the value of the thermal conductance, since the defective region is\nlimited within a narrow area around the defect center."
    },
    {
        "anchor": "Mapping momentum-dependent electron-phonon coupling and non-equilibrium\n  phonon dynamics with ultrafast electron diffuse scattering: Despite their fundamental role in determining material properties, detailed\nmomentum-dependent information on the strength of electron-phonon and\nphonon-phonon coupling (EPC and PPC, respectively) across the entire Brillouin\nzone (BZ) has proved difficult to obtain. Here we demonstrate that ultrafast\nelectron diffuse scattering (UEDS) directly provides such information. By\nexploiting symmetry-based selection rules and time-resolution, scattering from\ndifferent phonon branches can be distinguished even without energy resolution.\nUsing graphite as a model system, we show that UEDS patterns map the relative\nEPC and PPC strength through their profound sensitivity to photoinduced changes\nin phonon populations. We measure strong EPC to the $K$-point transverse\noptical phonon of $A_1'$ symmetry ($K-A_1'$) and along the entire longitudinal\noptical branch between $\\Gamma-K$, not only to the $\\Gamma-E_{2g}$ phonon as\npreviously emphasized. We also determine that the subsequent phonon relaxation\npathway involves three stages; decay via several identifiable channels to\ntransverse acoustic (TA) and longitudinal acoustic (LA) phonons (1-2 ps),\nintraband thermalization of the non-equilibrium TA/LA phonon populations (30-40\nps) and interband relaxation of the LA/TA modes (115 ps). Combining UEDS with\nultrafast angle-resolved photoelectron spectroscopy will yield a complete\npicture of the dynamics within and between electron and phonon subsystems,\nhelping to unravel complex phases in which the intertwined nature of these\nsystems have a strong influence on emergent properties.",
        "positive": "Size effects in micro and nanoscale materials fracture: Micro and nanoscale materials have remarkable mechanical properties, such as\nenhanced strength and toughness, but usually display sample-to-sample\nfluctuations and non-trivial size effects, a nuisance for engineering\napplications and an intriguing problem for science. Our understanding of\nsize-effects in small-scale materials has progressed considerably in the past\nfew years thanks to a growing number of experimental measurements on carbon\nbased nanomaterials, such as graphene carbon nanotubes, and on crystalline and\namorphous micro/nanopillars and micro/nanowires. At the same time, increased\ncomputational power allowed atomistic simulations to reach experimentally\nrelevant sample sizes. From the theoretical point of view, the standard\nanalysis and interpretation of experimental and computational data relies on\ntraditional extreme value theories developed decades ago for macroscopic\nsamples, with recent work extending some of the limiting assumptions of the\noriginal theories. In this review, we discuss the recent experimental and\nnumerical literature on micro and nanoscale fracture size effects, illustrate\nexisting theories pointing out their advantages and limitations and finally\nprovide a tutorial for analyzing fracture data from micro and nanoscale\nsamples. We discuss a broad spectrum of materials but provide at the same time\na unifying theoretical framework that should be helpful for materials\nscientists working on micro and nanoscale mechanics."
    },
    {
        "anchor": "Theoretical Insights into Non-Arrhenius Behaviors of Thermal Vacancies\n  in Anharmonic Crystals: Vacancies are prevalent point defects in crystals, but their thermal\nresponses are elusive. Herein, we formulate a simple theoretical model to shed\nlight on the vacancy evolution during heating. Vibrational excitations are\nthoroughly investigated via moment recurrence techniques in quantum statistical\nmechanics. On that basis, we carry out numerical analyses for Ag, Cu, and Ni\nwith the Sutton-Chen many-body potential. Our results reveal that the\nwell-known Arrhenius law is insufficient to describe the proliferation of\nvacancies. Specifically, anharmonic effects lead to a strong nonlinearity in\nthe Gibbs energy of vacancy formation. Our physical picture is well supported\nby previous simulations and experiments.",
        "positive": "Radial deformation measurements of isolated pairs of single-walled\n  carbon nanotubes: Interactions between atoms of bound single-walled carbon nanotubes (SWNTs)\nare known to cause measurable distortion to the tube's original circular\ncross-section frame. High-resolution transmission electron microscope (TEM)\ninvestigation was used here to directly image and verify these radial\ndeformations. The data presented here provide, for the first time, direct\nmeasurements of the deformations due to the interactions between isolated pairs\nof nanotubes. The deformation data is compared to previously reported\nexperimental and simulation results."
    },
    {
        "anchor": "Influence of Steel Alloying Components on Martensite Tetragonality: A formerly developed method aimed at determining the constituents of a merged\nX-ray pattern doublet was applied to estimate the fact that low-carbon\nmartensite with high concentration of strong carbide-forming elements possesses\nabnormally small tetragonality(c/a < 1). The article treats the nature of\ncarbide-forming and non-carbide-forming steel components influence on the\ntetragonality of martensite.",
        "positive": "Effective Mg Incorporation in CdMgO Alloy on Quartz Substrate Grown by\n  Plasma-assisted MBE: The development of CdMgO ternary alloy with a single cubic phase is\nchallenging but meaningful work for technological advancement. In this work, we\nhave grown a series of Cd1-xMgxO ternary random alloys with various Mg\nconcentrations (x = 0, 30, 32, 45, and 55%) on quartz substrate by\nplasma-assisted molecular beam epitaxy (PA-MBE) technique. The structural\ninvestigations of alloys were performed using the X-ray diffraction (XRD)\ntechnique. The decreases in average crystallite size and lattice parameters\nwere observed with an increase in Mg content in the alloys. XRD analysis\nconfirms a single cubic phase is obtained for alloy compositions. The elemental\nand morphological studies were carried out using energy dispersive x-ray (EDX)\nspectroscopy and atomic force microscope (AFM) technique, respectively. The\noptical investigation was carried out using UV-Vis spectroscopy. The optical\nbandgaps were estimated using the Tauc relation and it was varied from 2.34 eV\nto 3.47 eV by varying the Mg content from zero to 55% in the alloys. The Urbach\nenergy increases from 112 meV to 350 meV which suggests a more disordered\nlocalized state with an increase in Mg incorporation in the alloys."
    },
    {
        "anchor": "Nothing moves a surface: vacancy mediated surface diffusion: We report scanning tunneling microscopy observations, which imply that all\natoms in a close-packed copper surface move frequently, even at room\ntemperature. Using a low density of embedded indium `tracer' atoms, we\nvisualize the diffusive motion of surface atoms. Surprisingly, the indium atoms\nseem to make concerted, long jumps. Responsible for this motion is an ultra-low\ndensity of surface vacancies, diffusing rapidly within the surface. This\ninterpretation is supported by a detailed analysis of the displacement\ndistribution of the indium atoms, which reveals a shape characteristic for the\nvacancy mediated diffusion mechanism that we propose.",
        "positive": "Comparative study of phonon spectrum and thermal expansion of graphene,\n  silicene, germanene and blue phosphorene: Based on first-principles calculation using density functional theory, we\nstudy the vibrational properties and thermal expansion of mono-atomic\ntwo-dimensional honeycomb lattices: graphene, silicene, germanene and blue\nphosphorene. We focus on the similarities and differences of their properties,\nand try to understand them from their lattice structures. We illustrate that,\nfrom graphene to blue phosphorene, phonon bandgap develops due to large\nbuckling-induced mixing of the in-plane and out-of-plane phonon modes. This\nmixing also influences their thermal properties. Using quasi-harmonic\napproximation, we find that all of them show negative thermal expansion at room\ntemperature."
    },
    {
        "anchor": "Linear scaling electronic structure calculations and accurate sampling\n  with noisy forces: Numerical simulations based on electronic structure calculations are finding\never growing applications in many areas of physics. A major limiting factor is\nhowever the cubic scaling of the algorithms used. Building on previous work [F.\nR. Krajewski and M. Parrinello, Phys.Rev. B71, 233105 (2005)] we introduce a\nnovel statistical method for evaluating the inter-atomic forces which scales\nlinearly with system size and is applicable also to metals. The method is based\non exact decomposition of the fermionic determinant and on a mapping onto a\nfield theoretical expression. We solve exactly the problem of sampling the\nBoltzmann distribution with noisy forces. This novel approach can be used in\nsuch diverse fields as quantum chromodynamics, quantum Monte Carlo or colloidal\nphysics.",
        "positive": "Dispersive read-out of ferromagnetic resonance for strongly coupled\n  magnons and microwave photons: We demonstrate the dispersive measurement of ferromagnetic resonance in a\nyttrium iron garnet sphere embedded within a microwave cavity. The reduction in\nthe longitudinal magnetization at resonance is measured as a frequency shift in\nthe cavity mode coupled to the sphere. This measurement is a result of the\nintrinsic non-linearity in magnetization dynamics, indicating a promising route\ntowards experiments in magnon cavity quantum electro-dynamics."
    },
    {
        "anchor": "Machine learning reveals orbital interaction in crystalline materials: We propose a novel representation of crystalline materials named\norbital-field matrix (OFM) based on the distribution of valence shell\nelectrons. We demonstrate that this new representation can be highly useful in\nmining material data. Our experiment shows that the formation energies of\ncrystalline materials, the atomization energies of molecular materials, and the\nlocal magnetic moments of the constituent atoms in transition metal--rare-earth\nmetal bimetal alloys can be predicted with high accuracy using the OFM.\nKnowledge regarding the role of coordination numbers of transition-metal and\nrare-earth metal elements in determining the local magnetic moment of\ntransition metal sites can be acquired directly from decision tree regression\nanalyses using the OFM.",
        "positive": "Cyanographone and Isocyanographone $-$ two asymmetrically functionalized\n  graphene pseudohalides and their potential use in chemical sensing: Graphene pseudohalides are natural candidates for use in molecular sensing\ndue to their greater chemical activity as compared to both graphene halides and\npristine graphene. Though their study is still in its infancy, being hindered\nuntil recently by the unavailability of both selective and efficient procedures\nfor their synthesis, they promise to considerably widen the application\npotential of chemically modified graphenes. Herein, we employ vdW-DFT to study\nthe structural and electronic properties of two selected graphene pseudohalides\nnamely cyanographone and isocyanographone and investigate the potential use of\nthe latter as a chemical sensor via electron transport calculations."
    },
    {
        "anchor": "An efficient hybrid orbital representation for quantum Monte Carlo\n  calculations: The scale and complexity of quantum system to which real-space quantum Monte\nCarlo (QMC) can be applied in part depends on the representation and memory\nusage of the trial wavefunction. B-splines, the computationally most efficient\nbasis set, can have memory requirements exceeding the capacity of a single\ncomputational node. This situation has traditionally forced a difficult choice\nof either using slow internode communication or a potentially less accurate but\nsmaller basis set such as Gaussians. Here, we introduce a hybrid representation\nof the single particle orbitals that combine a localized atomic basis set\naround atomic cores and B-splines in the interstitial regions to reduce the\nmemory usage while retaining high speed of evaluation and either retaining or\nincreasing overall accuracy. We present a benchmark calculation for NiO\ndemonstrating a superior accuracy while using only one eighth the memory\nrequired for conventional B-splines. The hybrid orbital representation\ntherefore expands the overall range of systems that can be practically studied\nwith QMC.",
        "positive": "Design and Synthesis of Clathrate LaB8 with Superconductivity: Boron-based clathrate materials, typically with three-dimensional networks of\nB atoms, have tunable properties through substitution of guest atoms, but the\ntuning of B cages themselves has not yet been developed. By combining crystal\nstructural search with the laser-heated diamond anvil cell technique, we\nsuccessfully synthesized a new B-based clathrate boride, LaB8, at ~108 GPa and\n~2100 K. The novel structure has a B-richest cage, with 26 B atoms\nencapsulating a single La atom. LaB8 demonstrates phonon-mediated\nsuperconductivity with an estimated transition temperature of 14 K at ambient\npressure, mainly originating from electron-phonon coupling of B cage. This work\ncreates a prototype platform for subsequent investigation on tunable electronic\nproperties through the choice of captured atoms."
    },
    {
        "anchor": "Effect of cluster size of chalcogenide glass nanocolloidal solutions on\n  the surface morphology of spin-coated amorphous films: Amorphous chalcogenide thin film deposition can be achieved by a spin-coating\ntechnique from proper solutions of the corresponding glass. Films produced in\nthis way exhibit certain grain texture, which is presumably related to the\ncluster size in solution. This paper deals with the search of such a\ncorrelation between grain size of surface morphology of as-deposited\nspin-coated As33S67 chalcogenide thin films and cluster size of the glass in\nbutylamine solutions. Optical absorption spectroscopy and dynamic light\nscattering were employed to study optical properties and cluster size\ndistributions in the solutions at various glass concentrations. Atomic force\nmicroscopy is used to study the surface morphology of the surface of\nas-deposited and thermally stabilized spin-coated films. Dynamic light\nscattering revealed a concentration dependence of cluster size in solution.\nSpectral-dependence dynamic light scattering studies showed an interesting\nathermal photo-aggregation effect in the liquid state.",
        "positive": "Structural and Vibrational Properties of the TiOPc monolayer on Ag(111): The evolution of titanyl-phthalocyanine (TiOPc) thin films on Ag(111) has\nbeen investigated using IRAS, SPA-LEED and STM. In the (sub)monolayer regime\nvarious phases are observed that can be assigned to a 2D gas, a commensurate\nand a point-on-line phase. In all three phases the non-planar TiOPc molecule is\nadsorbed on Ag(111) in an oxygen-up configuration with the molecular\npi-conjugated backbone oriented parallel to the surface. The commensurate phase\nreveals a high packing density, containing two molecules at inequivalent\nadsorption sites within the unit cell. Both molecules assume different\nazimuthal orientations which is ascribed to preferred sites and azimuthal\norientations with respect to the Ag(111) substrate and, to a lesser extent, to\na minimization of repulsive Pauli interactions between adjacent molecules at\nshort distances. At full saturation of the monolayer the latter interaction\nbecomes dominant and the commensurate long range order is lost. DFT\ncalculations have been used to study different adsorption geometries of TiOPc\non Ag(111). The most stable configurations among those with pointing up oxygen\natoms (bridge+, bridgex, topx) seem to correspond to those identified\nexperimentally. The calculated dependence of the electronic structure and\nmolecular dipole on the adsorption site and configuration is found to be rather\nsmall."
    },
    {
        "anchor": "Anisotropy of Earth's D\" layer and stacking faults in the MgSiO3\n  post-perovskite phase: The post-perovskite phase of (Mg,Fe)SiO3 is believed to be the main mineral\nphase of the Earth's lowermost mantle (the D\" layer). Its properties explain\nnumerous geophysical observations associated with this layer - for example, the\nD'' discontinuity, its topography and seismic anisotropy within the layer. Here\nwe use a novel simulation technique, first-principles metadynamics, to identify\na family of low-energy polytypic stacking-fault structures intermediate between\nthe perovskite and post-perovskite phases. Metadynamics trajectories identify\nplane sliding involving the formation of stacking faults as the most favourable\npathway for the phase transition, and as a likely mechanism for plastic\ndeformation of perovskite and postperovskite. In particular, the predicted slip\nplanes are (010) for perovskite (consistent with experiment) and (110) for\npostperovskite (in contrast to the previously expected (010) slip planes).\nDominant slip planes define the lattice preferred orientation and elastic\nanisotropy of the texture. The (110) slip planes in post-perovskite require a\nmuch smaller degree of lattice preferred orientation to explain geophysical\nobservations of shear-wave anisotropy in the D\" layer.",
        "positive": "Organic-inorganic Copper(II)-based Material: a Low-Toxic, Highly Stable\n  Light Absorber beyond Organolead Perovskites: Lead halide perovskite solar cells have recently emerged as a very promising\nphotovoltaic technology due to their excellent power conversion efficiencies;\nhowever, the toxicity of lead and the poor stability of perovskite materials\nremain two main challenges that need to be addressed. Here, for the first time,\nwe report a lead-free, highly stable C6H4NH2CuBr2I compound. The C6H4NH2CuBr2I\nfilms exhibit extraordinary hydrophobic behavior with a contact angle of\napproximately 90 degree, and their X-ray diffraction patterns remain unchanged\neven after four hours of water immersion. UV-Vis absorption spectrum shows that\nC6H4NH2CuBr2I compound has an excellent optical absorption over the entire\nvisible spectrum. We applied this copper-based light absorber in printable\nmesoscopic solar cell for the initial trial and achieved a power conversion\nefficiency of 0.5%. Our study represents an alternative pathway to develop\nlow-toxic and highly stable organic-inorganic hybrid materials for photovoltaic\napplication."
    },
    {
        "anchor": "Crystal and magnetic structures of the spin-trimer compounds Ca3 Cu3xNix\n  (PO4)4 (x=0,1,2): Crystal and magnetic structures of a series of novel quantum spin trimer\nsystem Ca3Cu3xNix(PO4)4 (x=0,1,2) were studied by neutron powder diffraction at\nthe temperatures 1.5-290 K. The composition with one Ni per trimer (x=1) has a\nmonoclinic structure (space group P 21 /a, no. 14) with the unit cell\nparameters a = 17.71 A, b = 4.89 A, c = 8.85 A and = 123.84 deg at T=290 K. The\n(x=2) composition crystallizes in the C 2/c space group (no. 15) with the\ndoubled unit cell along c-axis. Each trimer is formed by two crystallographic\npositions: one in the middle and the second one at the ends of the trimer. We\nhave found that the middle position is occupied by the Cu2+, whereas the end\npositions are equally populated with the Cu2+ and Ni2+ for (x=1) while in the\n(x=2) the trimers were found to be of only one type Ni-Cu-Ni. Below TN = 20 K\nthe (x=2) compound shows an antiferromagnetic ordering with propagation vector\nstar {[1/2,1/2, 0], [-1/2,1/2, 0]} The magnetic structure is very well\ndescribed with the irreducible representation tau22 using both arms of the star\n{k} with the magnetic moments 1.89(1) muB and 0.62(2) muB for Ni2+ and Cu2+\nions, respectively. We note that our powder diffraction data cannot be fitted\nby a model containing only one arm of the propagation vector star. The\nCu/Ni-spins form both parallel and antiparallel configurations in the different\ntrimers, implying substantial effect of the inter-trimer interaction on the\noverall magnetic structure.",
        "positive": "Identification of 2H and 3R polytypes of MoS2 layered crystals using\n  photoluminescence spectroscopy: The excitonic radiative recombination of intercalated Cl2 molecules for two\ndifferent polytypes 2H-MoS2 and 3R-MoS2 layered crystals are presented. The\nstructure of the excitonic emission is unique and provides a robust\nexperimental signature of crystal polytype investigated. This result is\nconfirmed by X-ray diffraction analysis and DFT electronic band structure\ncalculations. Thus, the bound exciton emission provides a nondestructive\nfingerprint for the reliable identification of the polytype of MoS2 layered\ncrystals."
    },
    {
        "anchor": "Detuning dependence of high-order harmonic generation in monolayer\n  transition metal dichalcogenides: We theoretically investigate detuning-dependent properties of high-order\nharmonic generation (HHG) in monolayer transition metal dichalcogenides\n(TMDCs). In contrast to HHG in conventional materials, TMDCs show both parallel\nand perpendicular emissions with respect to the incident electric field. We\nfind that such an anomalous emission can be artificially controlled by the\nfrequency detuning of the incident electric fields, i.e., the parallel and\nperpendicular HHG can be strongly enhanced by multiphoton resonances. This\npeculiar phenomenon would provide a way for controlling HHG in TMDCs and\nstimulate the realization of novel optical devices.",
        "positive": "Tailoring strain in SrTiO3 compound by low energy He+ irradiation: The ability to generate a change of the lattice parameter in a near-surface\nlayer of a controllable thickness by ion implantation of strontium titanate is\nreported here using low energy He+ ions. The induced strain follows a\ndistribution within a typical near-surface layer of 200 nm as obtained from\nstructural analysis. Due to clamping effect from the underlying layer, only\nperpendicular expansion is observed. Maximum distortions up to 5-7% are\nobtained with no evidence of amorphisation at fluences of 1E16 He+ ions/cm2 and\nion energies in the range 10-30 keV."
    },
    {
        "anchor": "Laser induced ultrafast 3d and 4f spin dynamics in CoDy ferrimagnetic\n  alloys as a function of temperature: We report on an element- and time-resolved investigation of femtosecond laser\ninduced ultrafast dynamics of 3d and 4f spins in a ferrimagnetic Co80Dy20 alloy\nas a function of temperature. We observe an increase of the Co3d characteristic\ndemagnetization time and a decrease of the Dy4f demagnetization time when the\ntemperature is approaching the Curie temperature. It suggests that the critical\nslowing down regime, which affects the laser induced ultrafast dynamics in pure\n3d transition metals and 4f rare-earth ferromagnetic layers, vanishes for the\nDy sublattice in the CoDy alloy, in line with the theoretical predictions of\nthe Landau-Lifshitz-Bloch model.",
        "positive": "Static and Dynamic Monte Carlo Simulations of Br Electrodeposition on\n  Ag(100): We study the static and dynamic properties of bromine electrosorption onto\nsingle-crystal silver (100) electrodes by Monte Carlo simulation. At room\ntemperature the system displays a second-order phase transition between a\nlow-coverage disordered phase at more negative electrode potentials and a\nc(2x2) ordered phase with bromine coverage 1/2 at more positive potentials. We\nexplore the phase diagram and demonstrate that the broad shoulder observed in\nroom-temperature cyclic voltammograms is due to local fluctuations resembling\nordered phases with coverage 1/4 which exist in the model at much lower\ntemperatures. We construct a dynamic Monte Carlo algorithm using a thermally\nactivated stochastic barrier-hopping model for the microscopic dynamics. We use\nthis algorithm to study the phase ordering and disordering processes following\nsudden potential steps between the disordered phase and the c(2x2) phase and to\nstudy the sweep-rate dependence in simulated cyclic-voltammetry experiments."
    },
    {
        "anchor": "Exchange coupling in transition-metal nano-clusters on Cu(001) and\n  Cu(111) surfaces: We present results of density-functional calculations on the magnetic\nproperties of Cr, Mn, Fe and Co nano-clusters (1 to 9 atoms large) supported on\nCu(001) and Cu(111). The inter-atomic exchange coupling is found to depend on\ncompeting mechanisms, namely ferromagnetic double exchange and\nantiferromagnetic kinetic exchange. Hybridization-induced broadening of the\nresonances is shown to be important for the coupling strength. The cluster\nshape is found to weaken the coupling via a mechanism that comprises the\ndifferent orientation of the atomic d-orbitals and the strength of\nnearest-neighbour hopping. Especially in Fe clusters, a correlation of binding\nenergy and exchange coupling is also revealed.",
        "positive": "A STM model for Kondo Resonance on surface based on Schwinger-Keldysh\n  Contour: The paper had been withdrawn due to some technical problems. New version will\nbe uploaded near future."
    },
    {
        "anchor": "Temperature Dependence of the Viscoelastic Properties of a Natural\n  Gastropod Mucus by Brillouin Light Scattering Spectroscopy: Brillouin spectroscopy was used to probe the viscoelastic properties of a\nnatural gastropod mucus at GHz frequencies over the range -11 $^\\circ$C $\\leq T\n\\leq$ 52 $^\\circ$C. Anomalies in the temperature dependence of mucus\nlongitudinal acoustic mode peak parameters and associated viscoelastic\nproperties at $T = -2.5^\\circ$C, together with the appearance of a peak due to\nice at this temperature, suggest that the mucus undergoes a phase transition\nfrom a viscous liquid state to one in which liquid mucus and solid ice phases\ncoexist. Failure of this transition to proceed to completion even at -11\n$^\\circ$C is attributed to glycoprotein-water interaction. The temperature\ndependence of the viscoelastic properties and the phase behaviour suggest that\nwater molecules bind to glycoprotein at a temperature above the onset of\nfreezing and that the reduced ability of this bound water to take on a\nconfiguration that facilitates freezing is responsible for the observed\nfreezing point depression and gradual nature of the liquid-solid transition.",
        "positive": "Ab initio study of CrNF: the first half-metallic ferromagnet nitride\n  fluoride mimicking CrO2: Based on the different covalent versus ionic chemical bonding and\nisoelectronic rutile CrO2, CrNF is proposed starting from ordered rutile\nderivative structures subjected to full geometry optimizations. The ground\nstate structure defined from cohesive energies is of MgUO4-type, characterized\nby short covalent Cr-N and long ionic Cr-F distances. Like CrO2 it is a\nhalf-metallic ferromagnet with M = 2 Bohr Magnetons integer magnetization per\nformula unit with reduced band gap at minority spins. Major differences of\nmagnetic response to pressure characterize CrNF as a soft ferromagnet versus\nhard magnetic CrO2. The chemical bonding properties point to prevailing\ncovalent Cr-N versus ionic Cr-F bonding. Synthesis routes with two different\nprotocols are proposed and analyzed."
    },
    {
        "anchor": "Influence of the presence of multiple resonances on material parameter\n  determination using broadband ferromagnetic resonance spectroscopy: The influence of the presence of multiple resonances in ferromagnetic\nresonance spectra on extracted material parameters is investigated using\nnumerical simulations. Our results show that the systematic error of assuming\nan incorrect number of resonances for a material can lead to the extraction of\nmaterial parameters that significantly deviate from any of the true material\nparameters. When noise is present in experimental ferromagnetic resonance\nspectra increasing the frequency range of the broadband characterization can\nsignificantly reduce the error-margins when the data is analyzed assuming the\ncorrect number of resonances present in the material. For the cases\ninvestigated in this study it was found that analyzing the data using a single\nresonance results in extracted gyromagnetic ratios and effective magnetization\nparameters that are consistent with the weighted average of the true material\nparameters. We further provide a cautionary example regarding the extraction of\nthe inhomogeneous linewidth broadening and damping parameters of materials that\ncontain an unknown number of resonances.",
        "positive": "Direct visualization and control of SrOx segregation on semiconducting\n  Nb doped SrTiO3 (100) surface: We investigated how SrOx segregates on a Nb doped SrTiO3 (100) surface by in\nair annealing. Using atomic force and photoemission electron microscopes, we\ncan directly visualize the morphology and the electronic phase changes with\nSrOx segregation. SrOx islands less than 2 micron meter in size and 1-5 unit\ncells thick nucleate first and grow in a labyrinth domain pattern. After\nprolonged annealing, SrOx forms a ~10 nm thick film. We show that the domain\npattern can be controlled by introducing a surface miscut angle of SrTiO3.\nAdditionally, the segregated SrOx has a lower work function, compared to that\nof SrTiO3. These results suggest that the control and tunability of SrOx\nsegregation is applicable to the design of a new functional electronic devices\nin the semiconducting SrTiO3 based heterostructure."
    },
    {
        "anchor": "Qualitative model of high-$T_c$ superconductivity: We suggest a qualitative model of a high-$T_c$ superconductor, based on\nconsiderations of thermodynamics of phase transitions. As an example, we\nconsider the Mott transition and classify 5 solid phases around it. In our\nmodel, a combined electronic and structural instability causes segregation into\neither neutral or charged phases. A charged precipitate with a quantized\nelectric charge is a collective excitation of electrons, stabilized by a\ncollective athermal displacement of ions; this local variation of the charge\ndensity, accompanied by a local lattice deformation, can behave as a\nquasi\\-particle. A condensate of charged bosonic quasi\\-particles is\nresponsible for the superconductivity.",
        "positive": "$\\textit{Ab initio}$ anharmonic thermodynamic properties of cubic\n  CaSiO$_3$ perovskite: We present an $\\textit{ab initio}$ study of the thermodynamic properties of\ncubic CaSiO$_3$ perovskite (CaPv) over the pressure and temperature range of\nthe Earth's lower mantle. We compute the anharmonic phonon dispersions\nthroughout the Brillouin zone by utilizing the phonon quasiparticle approach,\nwhich characterizes the intrinsic temperature dependence of phonon frequencies\nand, in principle, captures full anharmonicity. Such temperature-dependent\nphonon dispersions are used to calculate $\\textit{ab initio}$ free energy in\nthe thermodynamic limit ($N \\rightarrow \\infty$) within the framework of the\nphonon gas model. Accurate free energy calculations enable us to investigate\ncubic CaPv's thermodynamic properties and thermal equation of state, where\nanharmonic effects are demonstrated. The present methodology provides an\nimportant theoretical approach for exploring phase boundaries, thermodynamic,\nand thermoelastic properties of strongly anharmonic materials at high pressures\nand temperatures."
    },
    {
        "anchor": "Voltage control of magnon spin currents in antiferromagnetic Cr2O3: Voltage-controlled spintronic devices utilizing the spin degree of freedom\nare desirable for future applications, and may allow energy-efficient\ninformation processing. Pure spin current can be created by thermal excitations\nin magnetic systems via the spin Seebeck effect (SSE). However, controlling\nsuch spin currents, only by electrical means, has been a fundamental challenge.\nHere, we investigate voltage control of the SSE in the antiferromagnetic\ninsulator Cr2O3. We demonstrate that the SSE response generated in this\nmaterial can be effectively controlled by applying a bias voltage, owing to the\nsensitivity of the SSE to the orientation of the magnetic sublattices as well\nas the existence of magnetoelectric couplings in Cr2O3. Our experimental\nresults are explained using a model based on the magnetoelectric effect in\nCr2O3.",
        "positive": "Nanoscale manipulation of the Mott insulating state coupled to charge\n  order in 1T-TaS2: Quantum states of strongly correlated electrons are of prime importance to\nunderstand exotic properties of condensed matter systems and the\ncontrollability over those states promises unique electronic devices such as a\nMott memory. As a recent example, a ultrafast switching device was demonstrated\nusing the transition between the correlated Mott insulating state and a\nhidden-order metallic state of a layered transition metal dichalcogenides\n1T-TaS2. However, the origin of the hidden metallic state was not clear and\nonly the macroscopic switching by laser pulse and carrier injection was\nreported. Here, we demonstrate the nanoscale manipulation of the Mott\ninsulating state of 1T-TaS2. The electron pulse from a scanning tunneling\nmicroscope switches the insulating phase locally into a metallic phase which is\ntextured with irregular domain walls in the charge density wave (CDW) order\ninherent to this Mott state. The metallic state is a novel correlated phase\nnear the Mott criticality with a coherent feature at the Fermi energy, which is\ninduced by the moderate reduction of electron correlation due to the\ndecoherence in CDW. This work paves the avenue toward novel nanoscale\nelectronic devices based on correlated electrons."
    },
    {
        "anchor": "Parity-odd multipoles, magnetic charges and chirality in haematite\n  (alfa-Fe2O3): Collinear and canted magnetic motifs in haematite were investigated by\nKokubun et al. (2008) using x-ray Bragg diffraction magnified at the iron\nK-edge, and analyses of observations led to various potentially interesting\nconclusions. We demonstrate that the reported analyses for both non-resonant\nand resonant magnetic diffraction at low energies near the absorption K-edge\nare not appropriate. In its place, we apply a radically different formulation,\nthoroughly tried and tested, that incorporates all magnetic contributions to\nresonant x-ray diffraction allowed by the established chemical and magnetic\nstructures. Essential to a correct formulation of diffraction by a magnetic\ncrystal with resonant ions at sites that are not centres of inversion symmetry\nare parity-odd atomic multipoles, time-even (polar) and time-odd\n(magneto-electric), that arise from enhancement by the electric-dipole (E1) -\nelectric-quadrupole (E2) event. Analyses of azimuthal-angle scans on two\nspace-group forbidden reflections, hexagonal (0, 0, 3)h and (0, 0, 9)h,\ncollected by Kokubun et al. above and below the Morin temperature (TM = 250K),\nallow us to obtain good estimates of contributing polar and magneto-electric\nmultipoles, including the iron anapole. We show, beyond reasonable doubt, that\navailable data are inconsistent with parity-even events only (E1-E1 and E2-\nE2). For future experiments, we show that chiral states of haematite couple to\ncircular polarization and differentiate E1-E2 and E2-E2 events, while the\ncollinear motif supports magnetic charges.",
        "positive": "MPInterfaces: A Materials Project based Python Tool for High-Throughput\n  Computational Screening of Interfacial Systems: A Materials Project based open-source Python tool, MPInterfaces, has been\ndeveloped to automate the high-throughput computational screening and study of\ninterfacial systems. The framework encompasses creation and manipulation of\ninterface structures for solid/solid hetero-structures, solid/implicit solvents\nsystems, nanoparticle/ligands systems; and the creation of simple\nsystem-agnostic workflows for in depth computational analysis using\ndensity-functional theory or empirical energy models. The package leverages\nexisting open-source high-throughput tools and extends their capabilities\ntowards the understanding of interfacial systems. We describe the various\nalgorithms and methods implemented in the package. Using several test cases, we\ndemonstrate how the package enables high-throughput computational screening of\nadvanced materials, directly contributing to the Materials Genome Initiative\n(MGI), which aims to accelerate the discovery, development, and deployment of\nnew materials."
    },
    {
        "anchor": "Structural and optical properties of cobalt slanted columnar thin films\n  conformally coated with graphene by chemical vapor deposition: A slanted cobalt sculptured columnar thin film was fabricated using glancing\nangle deposition, and coated subsequently with graphene using a low temperature\nchemical vapor deposition process. The graphene deposition process preserves\nshape and geometry of the sculptured thin film, which was confirmed by scanning\nelectron microscopy. According to the Raman spectroscopy results, the graphene\ncoating is two to three monolayers thick and has a high defect concentration.\nThe graphene coverage within the sculptured thin film is determined from\ngeneralized spectroscopic ellipsometry using a generalized anisotropic\nBruggeman effective medium approximation. The graphene coverage as well as\nstructural parameters of the thin film agree excellently with electron\nmicroscopy and Raman observations, and suggest that the graphene coating is\nconformal.",
        "positive": "Mapping domain junctions using 4D-STEM: toward controlled properties of\n  epitaxially grown transition metal dichalcogenide monolayers: Epitaxial growth has become a promising route to achieve highly crystalline\ncontinuous two-dimensional layers. However, high-quality layer production with\nexpected electrical properties is still challenging due to the defects induced\nby the coalescence between imperfectly aligned domains. In order to control\ntheir intrinsic properties at the device scale, the synthesized materials\nshould be described as a patchwork of coalesced domains. Here, we report\nmulti-scale and multistructural analysis on highly oriented epitaxial WS$_2$\nand WSe$_2$ monolayers using scanning transmission electron microscopy (STEM)\ntechniques. Characteristic domain junctions are first identified and classified\nbased on the detailed atomic structure analysis using aberration corrected STEM\nimaging. Mapping orientation, polar direction and phase at the micrometer scale\nusing four-dimensional STEM enabled to access the density and the distribution\nof the specific domain junctions. Our results validate a readily applicable\nprocess for the study of highly oriented epitaxial transition metal\ndichalcogenides, providing an overview of synthesized materials from large\nscale down to atomic scale with multiple structural information."
    },
    {
        "anchor": "Impact of seed density on continuous ultrathin nanodiamond film\n  formation: an analytical approach: An analytical mean field approach for describing the time evolution of film\ngrowth by seeding has been developed. The modeling deals with the generic case\nof anisotropic growth with different growth rates, respectively on -- and\nnormal to -- the substrate plane. The finite size of the seeds is considered by\nincluding spatial correlation effects among seeds through hard-core\ninteractions. The approach, based on probability theory, provides solution in\nclosed form for mean film thickness as a function of substrate coverage, seed\ndensity and initial size of the seeds. For negligible values of the initial\ncoverage of the substrate by seeds, manageable analytical expressions are\nattained. The model has been validated by comparison with experimental data\navailable in the literature. This study is significant in connection to the\npossibility of determining optimal growth conditions for ultrathin\nnanocrystalline diamond (NCD) film. In fact, the knowledge of the\nseeding/nucleation density that allows a given minimum average thickness of\ncontinuous film is of utmost importance for the development of technologically\nadvanced applications.",
        "positive": "Proximitized Materials: Advances in scaling down heterostructures and having an improved interface\nquality together with atomically-thin two-dimensional materials suggest a novel\napproach to systematically design materials. A given material can be\ntransformed through proximity effects whereby it acquires properties of its\nneighbors, for example, becoming superconducting, magnetic, topologically\nnontrivial, or with an enhanced spin-orbit coupling. Such proximity effects not\nonly complement the conventional methods of designing materials by doping or\nfunctionalization, but can also overcome their various limitations. In\nproximitized materials it is possible to realize properties that are not\npresent in any constituent region of the considered heterostructure. While the\nfocus is on magnetic and spin-orbit proximity effects with their applications\nin spintronics, the outlined principles provide also a broader framework for\nemploying other proximity effects to tailor materials and realize novel\nphenomena."
    },
    {
        "anchor": "Topology Classification from Chiral Symmetry: Chiral Phase Index and\n  Spin Correlations in Graphene Nanoribbons: Topology concepts have significantly deepened of our understanding in recent\nyears of the electronic properties of one-dimensional (1D) nano structures such\nas the graphene nanoribbons. Controlling topological electronic properties of\nGNRs has been demonstrated in both theoretical studies and experimental\nrealization. Most previous works rely on classification theory requiring both\ntime reversal and spatial symmetry of a unit cell in the 1D bulk material that\nis commensurate to its boundary. To access boundary structures that lead to\nunit cell with no spatial symmetry and to generalize the theory, we propose\nhere another classification scheme, using chiral symmetry, to arrive at a Z\nclassification that is not only applicable to GNRs with arbitrary terminations,\nbut also to any general 1D chiral structures. This theory, combining with\nLieb's theorem, moreover enables access to the electron's spin degree of\nfreedom, allowing for investigation of spin physics.",
        "positive": "Dissipation and adhesion hysteresis between (010) forsterite surfaces\n  using molecular-dynamics simulation and the Jarzynski equality: Dissipation and adhesion are important in many areas of materials science,\nincluding friction and lubrication, cold spray deposition, and\nmicro-electromechanical systems (MEMS). Another interesting problem is the\nadhesion of mineral grains during the early stages of planetesimal formation in\nthe early solar system. Molecular-dynamics (MD) simulation has often been used\nto elucidate dissipative properties, most often in the simulation of sliding\nfriction. In this paper, we demonstrate how the reversible and irreversible\nwork associated with interactions between planar surfaces can be calculated\nusing the dynamical contact simulation approach based on MD and empirical\npotentials. Moreover, it is demonstrated how the approach can obtain the\nfree-energy $\\Delta A(z)$ as a function of separation between two slabs using\nthe Jarzynksi equality applied to an ensemble of trajectories which deviate\nsignificantly from equilibrium. Furthermore, the dissipative work can also be\nobtained using this method without the need to compute an entire cycle from\napproach to retraction. It is expected that this technique might be used to\nefficiently compute dissipative properties which might enable the use of more\naccurate approaches including density-functional theory. In this paper, we\npresent results obtained for forsterite surfaces both with and without\nMgO-vacancy surface defects. It is shown that strong dissipation is possible\nwhen MgO-vacancy defects are present. The mechanism for strong dissipation is\nconnected to the tendency of less strongly-bound surface units to undergo large\ndisplacements including mass transfer between the two surfaces. Systems with\nstrong dissipation tend to exhibit a long-tailed distribution rather than the\nGaussian distribution often anticipated in near-equilibrium applications of the\nJE."
    },
    {
        "anchor": "Stoichiometry control of the electronic properties of the\n  LaAlO_3/SrTiO_3 heterointerface: We investigate the effect of the laser parameters of pulsed laser deposition\non the film stoichiometry and electronic properties of LaAlO_3/SrTiO_3 (001)\nheterostructures. The La/Al ratio in the LaAlO_3 films was varied over a wide\nrange from 0.88 to 1.15, and was found to have a strong effect on the interface\nconductivity. In particular, the carrier density is modulated over more than\ntwo orders of magnitude. The film lattice expansion, caused by cation\nvacancies, is found to be the important functional parameter. These results can\nbe understood to arise from the variations in the electrostatic boundary\nconditions, and their resolution, with stoichiometry.",
        "positive": "Excited-state potential-energy surfaces of metal-adsorbed organic\n  molecules from Linear Expansion \u0394-Self-Consistent Field\n  Density-Functional Theory (\u0394SCF-DFT): Accurate and efficient simulation of excited state properties is an important\nand much aspired cornerstone in the study of adsorbate dynamics on metal\nsurfaces. To this end, the recently proposed linear expansion \\Delta\nSelf-Consistent Field (le\\Delta SCF) method by Gavnholt et al. [Phys. Rev. B\n78, 075441 (2008)] presents an efficient alternative to time consuming\nquasi-particle calculations. In this method the standard Kohn-Sham equations of\nDensity-Functional Theory are solved with the constraint of a non-equilibrium\noccupation in a region of Hilbert-space resembling gas-phase orbitals of the\nadsorbate. In this work we discuss the applicability of this method for the\nexcited-state dynamics of metal-surface mounted organic adsorbates,\nspecifically in the context of molecular switching. We present necessary\nadvancements to allow for a consistent quality description of excited-state\npotential-energy surfaces (PESs), and illustrate the concept with the\napplication to Azobenzene adsorbed on Ag(111) and Au(111) surfaces. We find\nthat the explicit inclusion of substrate electronic states modifies the\ntopologies of intra-molecular excited-state PESs of the molecule due to image\ncharge and hybridization effects. While the molecule in gas phase shows a clear\nenergetic separation of resonances that induce isomerization and backreaction,\nthe surface-adsorbed molecule does not. The concomitant possibly simultaneous\ninduction of both processes would lead to a significantly reduced switching\nefficiency of such a mechanism."
    },
    {
        "anchor": "La-doped CH3NH3BaI3 : A Promising Transparent Conductor: Hybrid perovskites (CH3NH3PbI3) is one of the most promising novel materials\nfor solar harvesting. Toxicity of lead (Pb), however, has always remained a\nconcern. We investigated the electronic structure of complete replacement of Pb\nby alkaline earths (Ca, Sr, Ba) and found it to be wide band gapped (Eg)\nsemiconductors (band gap ~ 3.7 to 4.0 eV), and hence not suitable as absorber\nmaterial. This opens up a new avenue to explore these materials as transparent\nconductor (TC). We doped CH3NH3BaI3 (largest Eg) with La, which shifts its\nFermi level (EF) at conduction band bottom and induces states at EF for\nconduction. This is precisely what is required for a transparent conductor.\nOptical and transport properties simulated from linear response (within Density\nFunctional Theory (DFT)) calculations suggested it to be a very good TC\nmaterial with a high figure of merit ({\\sigma}/{\\alpha}), where {\\sigma} is the\nelectrical conductivity and {\\alpha} is the optical absorption coefficient.\nThis claim is also supported by our calculated results on density of states at\nEF, effective mass, carrier concentration etc. at various La-doping. We propose\nCH3NH3(Ba1-xLax)I3 (x~12.5%) to be a good TC material to be used in a all\nperovskite solar cell.",
        "positive": "Spin tunneling in junctions with disordered ferromagnets: We provide compelling evidence to establish that, contrary to one's\nelementary guess, the tunneling spin polarization (TSP) of amorphous CoFeB is\nlarger than that of highly textured fcc CoFeB. First principles atomic and\nelectronic structure calculations reveal striking agreement between the\nmeasured TSP and the predicted s-electron spin polarization. Given the\ndisordered structure of the ternary alloy, not only do these results strongly\nendorse our communal understanding of tunneling through AlOx, but they also\nportray the key concepts that demand primary consideration in such complex\nsystems."
    },
    {
        "anchor": "A Phase-Field Discrete Element Method to study chemo-mechanical coupling\n  in granular materials: This paper presents an extension of the discrete element method using a\nphase-field formulation to incorporate grain shape and its evolution. The\nintroduction of a phase variable enables an effective representation of grain\ngeometry and facilitates the application of physical laws, such as\nchemo-mechanical couplings, for modeling shape changes. These physical laws are\nsolved numerically using the finite element method coupled in a staggered\nscheme to the discrete element model. The efficacy of the proposed Phase-Field\nDiscrete Element Model (PFDEM) is demonstrated through its ability to\naccurately capture the real grain shape in a material subjected to dissolution\nonly and compute the stress evolution. It is then applied to model the\nphenomenon of pressure solution involving dissolution and precipitation in\ngranular materials at the microscale and enables to reproduce the creep\nresponse observed experimentally. This framework contributes to the enhanced\nunderstanding and simulation of complex behaviors in granular materials and\nsedimentary rocks for many geological processes like diagenesis or earthquake\nnucleation.",
        "positive": "Resonant tunneling in a quantum oxide superlattice: Resonant tunnelling is a quantum mechanical process that has long been\nattracting both scientific and technological attention owing to its intriguing\nunderlying physics and unique applications for high-speed electronics. The\nmaterials system exhibiting resonant tunnelling, however, has been largely\nlimited to the conventional semiconductors, partially due to their excellent\ncrystalline quality. Here we show that a deliberately designed transition metal\noxide superlattice exhibits a resonant tunnelling behaviour with a clear\nnegative differential resistance. The tunnelling occurred through an atomically\nthin, lanthanum {\\delta}-doped SrTiO3 layer, and the negative differential\nresistance was realized on top of the bipolar resistance switching typically\nobserved for perovskite oxide junctions. This combined process resulted in an\nextremely large resistance ratio (~10^5) between the high and low-resistance\nstates. The unprecedentedly large control found in atomically thin\n{\\delta}-doped oxide superlattices can open a door to novel oxide-based\nhigh-frequency logic devices."
    },
    {
        "anchor": "Training models using forces computed by stochastic electronic structure\n  methods: Quantum Monte Carlo (QMC) can play a very important role in generating\naccurate data needed for constructing potential energy surfaces. We argue that\nQMC has advantages in terms of a smaller systematic bias and an ability to\ncover phase space more completely. The stochastic noise can ease the training\nof the machine learning model. We discuss how stochastic errors affect the\ngeneration of effective models by analyzing the errors within a linear least\nsquares procedure, finding that there is an advantage to having many relatively\nimprecise data points for constructing models. We then analyze the effect of\nnoise on a model of many-body silicon finding that noise in some situations\nimproves the resulting model. We then study the effect of QMC noise on two\nmachine learning models of dense hydrogen used in a recent study of its phase\ndiagram. The noise enable us to estimate the errors in the model. We conclude\nwith a discussion of future research problems.",
        "positive": "Breakdown of compensation and persistence of non-saturating\n  magnetoresistance in WTe2 thin flakes: We present a detailed study of magnetoresistance \\r{ho}xx(H), Hall effect\n\\r{ho}xy(H), and electrolyte gating effect in thin (<100 nm) exfoliated\ncrystals of WTe2. We observe quantum oscillations in H of both \\r{ho}xx(H) and\n\\r{ho}xy(H), and identify four oscillation frequencies consistent with previous\nreports in thick crystals. \\r{ho}xy(H) is linear in H at low H consistent with\nnear-perfect electron-hole compensation, however becomes nonlinear and changes\nsign with increasing H, implying a breakdown of compensation. A field-dependent\nratio of carrier concentrations p/n can consistently explain \\r{ho}xx(H) and\n\\r{ho}xy(H) within a two-fluid model. We also employ an electrolytic gate to\nhighly electron-dope WTe2 with Li. The non-saturating \\r{ho}xx(H) persists to H\n= 14 T with magnetoresistance ratio exceeding 2 x 104 %, even with significant\ndeviation from perfect electron-hole compensation (p/n = 0.84), where the\ntwo-fluid model predicts a saturating \\r{ho}xx(H). Our results suggest\nelectron-hole compensation is not the mechanism for extremely large\nmagnetoresistance in WTe2, other alternative explanations need to be\nconsidered."
    },
    {
        "anchor": "Intrinsic interface states in InAs-AlSb heterostructures: We examine the possibility of intrinsic interface states bound to the plane\nof In-Sb chemical bonds at InAs/AlSb interfaces. Careful parameterization of\nthe bulk materials in the frame of the extended basis spds^* tight-binding\nmodel and recent progress in predictions of band offsets severely limit the\nspan of tight-binding parameters describing this system. We find that a\nheavy-hole like interface state bound to the plane of In-Sb bonds exists for a\nlarge range of values of the InSb/InAs band offset.",
        "positive": "Lattice dynamics of photoexcited insulators from constrained\n  density-functional perturbation theory: We present a constrained density functional perturbation theory scheme for\nthe calculation of structural and harmonic vibrational properties of insulators\nin the presence of an excited and thermalized electron-hole plasma. The method\nis ideal to tame ultrafast light induced structural transitions in the regime\nwhere the photocarriers thermalize faster than the lattice, the electron-hole\nrecombination time is longer than the phonon period and the photocarrier\nconcentration is large enough to be approximated by an electron-hole plasma.\nThe complete derivation presented here includes total energy, forces and stress\ntensor, variable cell structural optimization, harmonic vibrational properties\nand the electron-phonon interaction. We discuss in detail the case of zone\ncenter optical phonons not conserving the number of electrons and inducing a\nFermi shift in the photo-electron and hole distributions. We validate our\nimplementation by comparing with finite differences in Te and VSe2. By\ncalculating the evolution of the phonon spectrum of Te, Si and GaAs as a\nfunction of the fluence of the incoming laser light, we demonstrate that even\nat low fluences, corresponding to approximately 0.1 photocarriers per cell, the\nphonon spectrum is substantially modified with respect to the ground state one\nwith new Kohn anomalies appearing and a substantial softening of zone center\noptical phonons. Our implementation can be efficiently used to detect\nreversible transient phases and irreversible structural transition induced by\nultrafast light absorption."
    },
    {
        "anchor": "Feature-rich electronic properties of aluminum-doped graphenes: The electronic properties of aluminum-doped graphenes enriched by\nmulti-orbital hybridizations are investigated using first-principles\ncalculations. The feature-rich electronic structures exhibit the quasi-rigid\nred shifts of the carbon-created energy bands, the Al-dominated valence and\nconduction bands, and many free electrons in the conduction Dirac cone. These\nare directly reflected in the special structures of density of states (DOS).\nThe Al- and alkali-induced high free carrier densities are almost the same.\nThere exist certain important differences among the Al-, alkali- and\nhalogen-doped grapehenes, such as, the buckled or planar graphene, the\npreserved or seriously distorted Dirac cone, the existence of the\nadatom-dominated valence bands, the free electrons or holes, the degenerate or\nsplitting spin-related states, and the simple or complicated peaks in DOS. The\nsimilarities and differences mainly come from the diverse orbital\nhybridizations in adatom-C bonds, as indicated from the atom-dominated bands,\nthe spatial charge distributions and the orbital-projected DOS.",
        "positive": "Mechanical Properties of Graphene Papers: Graphene-based papers attract particular interests recently owing to their\noutstanding properties, the key of which is their layer-by-layer hierarchical\nstructures similar to the biomaterials such as bone, teeth and nacre, combining\nintralayer strong sp2 bonds and interlayer crosslinks for efficient load\ntransfer. Here we firstly study the mechanical properties of various interlayer\nand intralayer crosslinks via first-principles calculations and then perform\ncontinuum model analysis for the overall mechanical properties of\ngraphene-based papers. We find that there is a characteristic length scale\nl_{0}, defined as \\Sqrt{Dh_{0}/4G}, where D is the stiffness of the graphene\nsheet, h_{0} and G are the height of interlayer crosslink and shear modulus\nrespectively. When the size of the graphene sheets exceeds 3l_{0}, the\ntension-shear (TS) chain model that are widely used for nanocomposites fails to\npredict the overall mechanical properties of the graphene-based papers. Instead\nwe proposed here a deformable tension-shear (DTS) model by considering the\nelastic deformation of the graphene sheets, also the interlayer and intralayer\ncrosslinks. The DTS is then applied to predict the mechanics of graphene-based\npaper materials under tensile loading. According to the results we thus obtain,\noptimal design strategies are provided for designing graphene papers with\nultrahigh stiffness, strength and toughness."
    },
    {
        "anchor": "Full potential LAPW calculation of electron momentum density and related\n  properties of Li: Electron momentum density and Compton profiles in Lithium along $<100 >$,\n$<110>$, and $<111>$ directions are calculated using Full-Potential Linear\nAugmented Plane Wave basis within generalized gradient approximation. The\nprofiles have been corrected for correlations with Lam-Platzman formulation\nusing self-consistent charge density. The first and second derivatives of\nCompton profiles are studied to investigate the Fermi surface breaks. Decent\nagreement is observed between recent experimental and our calculated values.\nOur values for the derivatives are found to be in better agreement with\nexperiments than earlier theoretical results. Two-photon momentum density and\none- and two-dimensional angular correlation of positron annihilation radiation\nare also calculated within the same formalism and including the\nelectron-positron enhancement factor.",
        "positive": "Statistical Thermodynamics of Dislocations in Solids: This review is a simplified summary of the thermodynamic dislocation theory,\nwith special emphasis on the role of an effective temperature. Materials\nscientists, for decades, have asserted that statistical thermodynamics is not\napplicable to dislocations. By use of simple, first-principles analyses and\ncomparisons with experimental data, I argue that these scientists have been\nwrong, and that this venerable field urgently needs to be revitalized because\nof its wide-ranging fundamental and technological importance. In addition to\ndescribing recent progress in understanding strain hardening, yielding, shear\nbanding, and the like, I argue that the thermodynamic dislocation theory can\nlead to a much needed, first-principles understanding of brittle and ductile\nfracture in crystalline solids."
    },
    {
        "anchor": "Anisotropic Infrared Response and Orientation-dependent Strain-tuning of\n  the Electronic Structure in Nb2SiTe4: Two-dimensional materials with tunable in-plane anisotropic infrared response\npromise versatile applications in polarized photodetectors and field-effect\ntransistors. Black phosphorus is a prominent example. However, it suffers from\npoor ambient stability. Here, we report the strain-tunable anisotropic infrared\nresponse of a layered material Nb2SiTe4, whose lattice structure is similar to\nthe 2H-phase transition metal dichalcogenides (TMDCs) with three different\nkinds of building units. Strikingly, some of the strain-tunable optical\ntransitions are crystallographic axis-dependent, even showing opposite shift\nwhen uniaxial strain is applied along two in-plane principal axes. Moreover,\nG0W0-BSE calculations show good agreement with the anisotropic extinction\nspectra. The optical selection rules are obtained via group theory analysis,\nand the strain induced unusual shift trends are well explained by the orbital\ncoupling analysis. Our comprehensive study suggests that Nb2SiTe4 is a good\ncandidate for tunable polarization-sensitive optoelectronic devices.",
        "positive": "Ferromagnetism in 2D Vanadium Diselenide: Two-dimensional (2D) Van der Waals ferromagnets carry the promise of\nultimately miniature spintronics and information storage devices. Among the\nnewly discovered 2D ferromagnets all inherit the magnetic ordering from their\nbulk ancestors. Here we report a new 2D ferromagnetic semiconductor at room\ntemperature, 2H phase vanadium diselenide (VSe2) which show ferromagnetic at 2D\nform only. This unique 2D ferromagnetic semiconductor manifests an enhanced\nmagnetic ordering owing to structural anisotropy at 2D limit."
    },
    {
        "anchor": "Robust broad spectral photodetection (UV-NIR) and ultra high\n  responsivity investigated in nanosheets and nanowires of Bi2Te3 under harsh\n  nano-milling conditions: Due to miniaturization of device dimensions, the next generations\nphotodetector based devices are expected to be fabricated from robust\nnanostructured materials. Hence there is an utmost requirement of investigating\nexotic optoelectronic properties of nanodevices fabricated from new novel\nmaterials and testing their performances at harsh conditions. The recent\nadvances on 2D layered materials indicate exciting progress on broad spectral\nphotodetection (BSP) but still there is a great demand for fabricating\nultra-high performance photodetectors made from single material sensing broad\nelectromagnetic spectrum since the detection range 325 nm to 1550 nm is not\ncovered by the conventional Si or InGaAs photodetectors. Alternatively, Bi2Te3\nis a layered material, possesses exciting optoelectronic, thermoelectric,\nplasmonics properties. Here we report robust photoconductivity measurements on\nBi2Te3 nanosheets and nanowires demonstrating BSP from UV to NIR. The\nnanosheets of Bi2Te3 show the best ultra-high photoresponsivity (~74 A/W at\n1550 nm ). Further these nanosheets when transform into nanowires using harsh\nFIB milling conditions exhibit about one order enhancement in the\nphotoresponsivity without affecting the performance of the device even after 4\nmonths of storage at ambient conditions. An ultra-high photoresponsivity and\nBSP indicate exciting robust nature of topological insulator based nanodevices\nfor optoelectronic applications.",
        "positive": "Antiskyrmions and their electrical footprint in crystalline mesoscale\n  structures of Mn$_{1.4}$PtSn: Skyrmionic materials hold the potential for future information technologies,\nsuch as racetrack memories. Key to that advancement are systems that exhibit\nhigh tunability and scalability, with stored information being easy to read and\nwrite by means of all-electrical techniques. Topological magnetic excitations\nsuch as skyrmions and antiskyrmions, give rise to a characteristic topological\nHall effect. However, the electrical detection of antiskyrmions, in both thin\nfilms and bulk samples has been challenging to date. Here, we apply\nmagneto-optical microscopy combined with electrical transport to explore the\nantiskyrmion phase as it emerges in crystalline mesoscale structures of the\nHeusler magnet Mn$_{1.4}$PtSn. We reveal the Hall signature of antiskyrmions in\nline with our theoretical model, comprising anomalous and topological\ncomponents. We examine its dependence on the vertical device thickness, field\norientation, and temperature. Our atomistic simulations and experimental\nanisotropy studies demonstrate the link between antiskyrmions and a complex\nmagnetism that consists of competing ferromagnetic, antiferromagnetic, and\nchiral exchange interactions, not captured by micromagnetic simulations."
    },
    {
        "anchor": "Analysis of magneto-optical Kerr spectra of ferrimagnetic Mn$_4$N: Simulations of magneto-optical Kerr effect in biaxially strained Mn$_4$N are\nperformed using density functional theory and linear response theory. We\nconsider three ferrimagnetic phases, two collinear and one noncollinear, which\nhave been corroborated separately by earlier studies. The simulated spectra are\ncompared to magneto-optical data available in recent literature. A collinear\nferrimagnetic phase with a small saturation magentization, a large\nperpendicular anisotropy, and Curie temperature above 700~K is found to be\nconsistent with the measured spectra. We hypothesise that an admixture of the\nnoncollinear phase, which could explain the lower than predicted net moment and\nmagnetic anisotropy observed experimentally, is also present.",
        "positive": "Spin Waves in a Periodically Layered Magnetic Nanowire: We report a simple theoretical derivation of the spectrum and damping of spin\nwaves in a cylindrical periodically structured magnetic nanowire (cylindrical\nmagnonic crystal) in the \"effective medium\" approximation. The dependence of\nthe \"effective\" magnetic parameters upon the individual layer parameters is\nshown to be different from the arithmetic average over the volume of the\nsuperlattice. The formulae that are obtained can be applied firstly in the\ndescription of spin wave dispersion in the first allowed band of the structure;\nand secondly in the design of a magnonic crystal with band-gaps in an arbitrary\npart of the spin wave spectrum."
    },
    {
        "anchor": "Local probing of the field emission stability of vertically aligned\n  multiwalled carbon nanotubes: Metallic cantilever in high vacuum atomic force microscope has been used as\nanode for field emission experiments from densely packed vertically aligned\nmulti-walled carbon nanotubes. The high spatial resolution provided by the\nscanning probe technique allowed precise setting of the tip-sample distance in\nthe submicron region. The dimension of the probe (curvature radius below 50nm)\nallowed to measure current contribution from sample areas smaller than 1um^2.\nThe study of long-term stability evidenced that on these small areas the field\nemission current remains stable (within 10% fluctuations) several hours (at\nleast up to 72 hours) at current intensities between 10-5A and 10-8A.\nImprovement of the current stability has been observed after performing\nlong-time Joule heating conditioning to completely remove possible adsorbates\non the nanotubes.",
        "positive": "Damage threshold in pre-heated materials exposed to intense X-rays: Materials exposed to ultrashort intense x-ray irradiation may experience\nvarious damaging conditions depending on the in-situ temperature. A pre-heated\ntarget exposed to intense x-rays plays a crucial role in numerous systems of\nphysical-technical importance, ranging from the heavily-, and repeatedly\nradiation-loaded optics at x-ray free-electron laser facilities, to the first\nwall of prospective inertial fusion reactors. We study theoretically the damage\nthreshold dependence on the temperature in different classes of materials: an\ninsulator (diamond), a semiconductor (silicon), a metal (tungsten), and an\norganic polymer (PMMA). The numerical techniques used here enable us to trace\nthe evolution of both, an electronic state and atomic dynamics of the\nmaterials. It includes damage mechanisms such as thermal damage (induced by an\nincrease of the atomic temperature due to energy transfer from x-ray-excited\nelectrons) and nonthermal phase transitions (induced by changes in the\ninteratomic potential due to excitation of electrons). We demonstrate that in\nthe pre-heated materials, typically, the thermal damage threshold stays the\nsame or lowers with the increase of the in-situ temperature, whereas nonthermal\ndamage thresholds may be lowered or raised, depending on the particular\nmaterial and specifics of the damage kinetics."
    },
    {
        "anchor": "Decoherence of electron spin qubits in Si-based quantum computers: Direct phonon spin-lattice relaxation of an electron qubit bound by a donor\nimpurity or quantum dot in SiGe heterostructures is investigated. The aim is to\nevaluate the importance of decoherence from this mechanism in several important\nsolid-state quantum computer designs operating at low temperatures. We\ncalculate the relaxation rate $1/T_1$ as a function of [100] uniaxial strain,\ntemperature, magnetic field, and silicon/germanium content for Si:P bound\nelectrons. The quantum dot potential is much smoother, leading to smaller\nsplittings of the valley degeneracies. We have estimated these splittings in\norder to obtain upper bounds for the relaxation rate. In general, we find that\nthe relaxation rate is strongly decreased by uniaxial compressive strain in a\nSiGe-Si-SiGe quantum well, making this strain an important positive design\nfeature. Ge in high concentrations (particularly over 85%) increases the rate,\nmaking Si-rich materials preferable. We conclude that SiGe bound electron\nqubits must meet certain conditions to minimize decoherence but that\nspin-phonon relaxation does not rule out the solid-state implementation of\nerror-tolerant quantum computing.",
        "positive": "Control and characterization of the preferential crystalline orientation\n  of MoS2 2D flakes in printed layers: The recent development of Liquid Phase Exfoliation (LPE) of 2D materials has\nenabled the formulation of inks with rheological properties adapted to numerous\nliquid deposition methods. This has allowed the fabrication of various types of\nprinted devices with unique features stemming from the nano-structure of the\nprinted 2D layers. In this short communication, we demonstrate that the\npreferred crystalline orientation of printed MoS2 flakes depends drastically\nupon the printing method employed to deposit the layers. Using angle resolved\nX-Ray Diffraction (XRD) to measure Pole Figure and subsequently calculate\nOrientation Distribution Functions (ODF), we show that the spin-coating method\nyields the best basal fiber texture, most likely because of the shear force at\nwork on the flakes during the deposition process. This interim report thereby\npaves the way to further investigations and fine control of the preferred\ncrystalline orientation of printed 2D flakes for the development of dedicated\ndevices."
    },
    {
        "anchor": "Resonant inelastic x-ray scattering probes the electron-phonon coupling\n  in the spin-liquid kappa-(BEDT-TTF)2Cu2(CN)3: Resonant inelastic x-ray scattering at the N K edge reveals clearly resolved\nharmonics of the anion plane vibrations in the kappa-(BEDT-TTF)2Cu2(CN)3\nspin-liquid insulator. Tuning the incoming light energy at the K edge of two\ndistinct N sites permits to excite different sets of phonon modes. Cyanide CN\nstretching mode is selected at the edge of the ordered N sites which are more\nstrongly connected to the BEDT-TTF molecules, while positionally disordered N\nsites show multi-mode excitation. Combining measurements with calculations on\nan anion plane cluster permits to estimate the sitedependent electron-phonon\ncoupling of the modes related to nitrogen excitation.",
        "positive": "Evaluating Gilbert Damping in Magnetic Insulators from First Principles: Magnetic damping has a significant impact on the performance of various\nmagnetic and spintronic devices, making it a long-standing focus of research.\nThe strength of magnetic damping is usually quantified by the Gilbert damping\nconstant in the Landau-Lifshitz-Gilbert equation. Here we propose a\nfirst-principles based approach to evaluate the Gilbert damping constant\ncontributed by spin-lattice coupling in magnetic insulators. The approach\ninvolves effective Hamiltonian models and spin-lattice dynamics simulations. As\na case study, we applied our method to Y$_3$Fe$_5$O$_{12}$, MnFe$_2$O$_4$ and\nCr$_2$O$_3$. Their damping constants were calculated to be $0.8\\times10^{-4}$,\n$0.2\\times10^{-4}$, $2.2\\times 10^{-4}$, respectively at a low temperature. The\nresults for Y$_3$Fe$_5$O$_{12}$ and Cr$_2$O$_3$ are in good agreement with\nexperimental measurements, while the discrepancy in MnFe$_2$O$_4$ can be\nattributed to the inhomogeneity and small band gap in real samples. The\nstronger damping observed in Cr$_2$O$_3$, compared to Y$_3$Fe$_5$O$_{12}$,\nessentially results from its stronger spin-lattice coupling. In addition, we\nconfirmed a proportional relationship between damping constants and the\ntemperature difference of subsystems, which had been reported in previous\nstudies. These successful applications suggest that our approach serves as a\npromising candidate for estimating the Gilbert damping constant in magnetic\ninsulators."
    },
    {
        "anchor": "Strain driven migration of In during the growth of InAs/GaAs quantum\n  posts: Using the mechano-optical stress sensor technique, we observe a\ncounter-intuitive reduction of the compressive stress when InAs is deposited on\nGaAs (001) during growth of quantum posts. Through modelling of the strain\nfields, we find that such anomalous behaviour can be related to the\nstrain-driven detachment of In atoms from the crystal and their surface\ndiffusion towards the self-assembled nanostructures.",
        "positive": "Dynamical effects in Bragg coherent x-ray diffraction imaging on finite\n  crystals: We present simulations of Bragg Coherent X-ray Diffractive Imaging (CXDI)\ndata from finite crystals in the frame of the dynamical theory of x-ray\ndiffraction. The developed approach is based on numerical solution of modified\nTakagi-Taupin equations and can be applied for modeling of a broad range of\nx-ray diffraction experiments with finite three-dimensional crystals of\narbitrary shape also in the presence of strain. We performed simulations for\nnanocrystals of a cubic and hemispherical shape of different sizes and provided\na detailed analysis of artifacts in the Bragg CXDI reconstructions introduced\nby the dynamical diffraction. A convenient way to treat effects of refraction\nand absorption supported by analytical derivations is described. Our results\nelucidate limitations for the kinematical approach in the Bragg CXDI and\nsuggest a natural criterion to distinguish between kinematical and dynamical\ncases in coherent x-ray diffraction on a finite crystal."
    },
    {
        "anchor": "Surfactant-aided exfoliation of molydenum disulphide for ultrafast pulse\n  generation through edge-state saturable absorption: We use liquid phase exfoliation to produce dispersions of molybdenum\ndisulphide (MoS2) nanoflakes in aqueous surfactant solutions. The chemical\nstructures of the bile salt surfactants play a crucial role in the exfoliation\nand stabilization of MoS2. The resultant MoS2 dispersions are heavily enriched\nin single and few (<6) layer flakes with large edge to surface area ratio. We\nuse the dispersions to fabricate free-standing polymer composite wide-band\nsaturable absorbers to develop mode-locked and Q- switched fibre lasers,\ntunable from 1535-1565 and 1030-1070 nm, respectively. We attribute this\nsub-bandgap optical absorption and its nonlinear saturation behaviour to\nedge-mediated states introduced within the material band-gap of the exfoliated\nMoS2 nanoflakes.",
        "positive": "Two New Members of the Covalent Organic Frameworks Family: Crystalline\n  2D-Oxocarbon and 3D-Borocarbon Structures: While graphene oxide (GO) is representative of a disordered phase of\noxocarbons with lackluster electronic properties, the coexistence of ordered,\nstoichiometric solid-state carbon oxides with graphene brings renewed momentum\nto the exploration of two-dimensional crystalline oxocarbons. This enduring\nsubject, spanning decades, has recently witnessed significant advancements. In\nthis context, our study delves into a novel material class, COF-66, notable for\nits meticulously ordered two-dimensional crystalline structure and intrinsic\nporosity. Employing a global optimization algorithm alongside\ndensity-functional calculations, our investigation highlights a standout member\nwithin the COF-66 family exceptional quasi-flat oxocarbon (C6O6)exhibiting an\nunconventional oxygen-decorated pore configuration. This pioneering study\nintroduces C6O6 as an innovative entrant into the crystalline carbon oxide\narena, augmenting the established understanding alongside the well-recognized\ngraphene oxide and two graphene monoxide, i.e. {\\alpha}-GMO and \\b{eta}-GMO.\nExpanding the exploration, the COF-66 series encompasses 2D-porous carbon\nnitride (C6N6) and the recently synthesized 2D-porous boroxine (B6O6), adhering\nto a generalized stoichiometry of X6Y6, where X = B, C, and Y = B, N, O, with X\n6= Y. Remarkably, the entire COF-66 ensemble adopts a 2D-crystalline framework,\nwith the exception of C6B6, which assumes a distinct 3D-crystalline\narrangement. Employing the PBE (HSE06) level of theory, our electronic\nstructure calculations yield band gap values of 0.01 (0.05) eV, 3.68 (5.29) eV,\n0.00 (0.23) eV, and 1.53 (3.09) eV for B6N6, B6O6, C6B6, and C6N6,\nrespectively, reinforcing and aligning with prior investigations."
    },
    {
        "anchor": "Probing magnetic orbitals and Berry curvature with circular dichroism in\n  resonant inelastic X-ray scattering: Resonant inelastic X-ray scattering (RIXS) can probe localized excitations at\nselected atoms in materials, including particle-hole transitions between the\nvalence and conduction bands. These transitions are governed by fundamental\nproperties of the corresponding Bloch wave-functions, including orbital and\nmagnetic degrees of freedom, and quantum geometric properties such as the Berry\ncurvature. In particular, orbital angular momentum (OAM), which is closely\nlinked to the Berry curvature, can exhibit a nontrivial momentum dependence. We\ndemonstrate how information on such OAM textures can be extracted from the\ncircular dichroism in RIXS. Based on accurate modeling with first-principles\ntreatment of the key ingredient -- the light-matter interaction -- we simulate\ndichroic RIXS spectra for the prototypical transition metal dichalcogenide\nMoSe$_2$ and the two-dimensional topological insulator 1T$^\\prime$-MoS$_2$.\nGuided by an intuitive picture for the optical selection rules, we discuss how\nthe momentum-dependent OAM manifests itself in the dichroic RIXS signal if one\ncontrols the momentum transfer. Our calculations are performed for typical\nexperimental geometries and parameter regimes, and demonstrate the possibility\nof observing the predicted circular dichroism in forthcoming experiments. Thus,\nour work establishes a new avenue to observing Berry curvature and topological\nstates in quantum materials.",
        "positive": "Ultrafast asymmetric Rosen-Zener-like coherent phonon responses observed\n  in silicon: We investigate the spectral profiles of time signals attributed to coherent\nphonon generation in an undoped Si crystal. Here, the retarded\nlongitudinal-optical (LO) phonon Green function relevant to the temporal\nvariance of induced charge density of ionic cores is calculated by employing\nthe polaronic quasiparticle model developed by the authors [Y. Watanabe et al.,\nPhys. Rev. B 95, 014301 (2017); ibid., 96, 125204 (2017)]. The spectral\nasymmetry is revealed in the frequency domain of the signals under the\ncondition that an LO phonon mode stays almost energetically resonant with a\nplasmon mode in the early time region; this lasts for approximately 100 fs\nimmediately after the irradiation of an ultrashort pump-laser pulse. It is\nunderstood that based on the adiabatic picture in time, this asymmetry is\ncaused by the Rosen-Zener coupling between both modes. The associated\nexperimental results are obtained by measuring time-dependent electro-optic\nreflectivity signals, and it is proved that these are in harmony with the\ncalculated ones. The spectra become more symmetric, as the photoexcited carrier\ndensity further changes from that meeting the above condition to higher and\nlower sides of carrier densities. Moreover, the effect of optical nutation of\ncarrier density on the CP signals is addressed, and the present results are\ncompared with the asymmetry caused by transient Fano resonance, and the\nspectral profiles observed in a GaAs crystal in the text."
    },
    {
        "anchor": "Unusual polarization patterns in flat epitaxial ferroelectric\n  nanoparticles: Interest in epitaxial ferroelectric nanoislands was growing rapidly in recent\nyears driven by their potential for devices, especially ultradense memories.\nRecent advances in the \"bottom- up\" (self-assembly) nanometer scale techniques\nhave opened up the opportunities of fabricating high-quality epitaxial\nferroelectric nanoislands with extremely small thickness and lateral size on\nthe order of 1 nm and 20 nm, respectively. On the other hand, recent emergence\nof powerful probes, such as piezoresponse force microscopy (PFM), has enabled\nimaging of a local domain structure with sub-10 nm resolution. In spite of\nthose developments, a clear understanding of the polarization patterns in\nepitaxial ferroelectric nanoislands is lacking, and some important\ncharacteristics, like a critical lateral size for ferroelectricity, are not yet\nestablished. Here, we perform ab-initio studies of non-electroded epitaxial\nPb(Zr0.5Ti0.5)O3 and BaTiO3 nanoislands and show the existence of novel\npolarization patterns driven by the misfit strains and/or anisotropy energy.\nThe results allow interpretation of the data and design of the ferroelectric\nnanostructures with tailored response to external field.",
        "positive": "Why Ultrafast Photo-induced CO Desorption Dominates over Oxidation on\n  Ru(0001): CO oxidation on Ru(0001) is a long-standing example of a reaction that, being\nthermally forbidden in ultra-high vacuum, can be activated by femtosecond laser\npulses. In spite of its relevance, the precise dynamics of the photo-induced\noxidation process as well as the reasons behind the dominant role of the\ncompeting CO photo-desorption remain unclear. Here we use ab initio molecular\ndynamics with electronic friction that account for the highly excited and\nnon-equilibrated system created by the laser to investigate both reactions. Our\nsimulations successfully reproduce the main experimental findings: the\nexistence of photo-induced oxidation and desorption, the large desorption to\noxidation branching ratio, and the changes in the O K-edge X-ray absorption\nspectra attributed to the initial stage of the oxidation process. Now, we are\nable to monitor in detail the ultrafast CO desorption and CO oxidation\noccurring in the highly-excited system and to disentangle what causes the\nunexpected inertness to the otherwise energetically favored oxidation."
    },
    {
        "anchor": "Chemical Bond-Based Representation of Materials: This paper introduces a new representation method that is mainly based on\nchemical bonds among atoms in materials. Each chemical bond and its surrounded\natoms are considered as a unified unit or a local structure that is expected to\nreflect a part of materials' nature. First, a material is separated into local\nstructures; and then represented as matrices, each of which is computed by\nusing information about the corresponding chemical bond as well as\norbital-field matrices of two related atoms. After that, all local structures\nof the material are utilized by using the statistics point of view. In the\nexperiment, the new method was applied into a materials informatics application\nthat aims at predicting atomization energies using QM7 data set. The results of\nthe experiment show that the new method is more effective than two\nstate-of-the-art representation methods in most of the cases.",
        "positive": "Exciton-phonon interaction calls for a revision of the \"exciton\" concept: The concept of \\textit{optical} exciton - a photo-excited bound electron-hole\npair within a crystal - is routinely used to interpret and model a wealth of\nexcited-state phenomena in semiconductors. Beside originating sub-band gap\nsignatures in optical spectra, optical excitons have also been predicted to\ncondensate, diffuse, recombine, relax. However, all these phenomena are rooted\non a theoretical definition of the excitonic state based on the following\nsimple picture: \"excitons\" are actual particles that both appear as peaks in\nthe linear absorption spectrum and also behave as well-defined quasiparticles.\nIn this paper we show, instead, that the electron-phonon interaction decomposes\nthe initial optical excitons into \\textit{elemental} excitons, the latter being\na different kind of bound electron-hole pairs lacking the effect caused by the\ninduced, classical, electric field. This is demonstrated within a many-body\nperturbation theory approach starting from the interacting electronic\nHamiltonian including both electron-phonon and electron-hole interactions. We\nthen apply the results on two realistic systems, monolayer MoS$_2$ (where the\nlowest-bound exciton is optically inactive) and monolayer MoSe$_2$ (where it is\noptically active), using first-principles methods to compute the exciton-phonon\ncoupling matrix elements. Among the consequences of optical-elemental\ndecomposition, we point to a homogeneous broadening of absorption peaks\noccurring even for the lowest-bound optical exciton, we demonstrate this by\ncomputing exciton-phonon transition rates. More generally, our findings suggest\nthat the optical excitons gradually lose their initial structure and evolve as\nelemental excitons. These states can be regarded as the real intrinsic\nexcitations of the interacting system, the ones that survive when the external\nperturbation and the induced electric fields have vanished."
    },
    {
        "anchor": "Mean-field potential calculations of high-pressure equation of state for\n  shock-compressed BeO: A systematic study of the Hugoniot equation of state, phase transition, and\nthe other thermodynamic properties including the Hugoniot temperature, the\nelectronic and ionic heat capacities, and the Gr\\\"{u}neisen parameter for\nshock-compressed BeO, is presented by calculating the total free energy. The\nmethod of calculations combines first-principles treatment for 0-K and finite-T\nelectronic contribution and the mean-field-potential approach for the\nvibrational contribution of the lattice ion to the total energy. Our calculated\nHugoniot shows good agreement with the experimental data.",
        "positive": "Comparing molecules and solids across structural and alchemical space: Evaluating the (dis)similarity of crystalline, disordered and molecular\ncompounds is a critical step in the development of algorithms to navigate\nautomatically the configuration space of complex materials. For instance, a\nstructural similarity metric is crucial for classifying structures, searching\nchemical space for better compounds and materials, and driving the next\ngeneration of machine-learning techniques for predicting the stability and\nproperties of molecules and materials. In the last few years several strategies\nhave been designed to compare atomic coordination environments. In particular,\nthe Smooth Overlap of Atomic Positions (SOAP) has emerged as an elegant\nframework to obtain translation, rotation and permutation-invariant descriptors\nof groups of atoms, driven by the design of various classes of machine-learned\ninter-atomic potentials. Here we discuss how one can combine such local\ndescriptors using a Regularized Entropy Match (REMatch) approach to describe\nthe similarity of both whole molecular and bulk periodic structures,\nintroducing powerful metrics that enable the navigation of alchemical and\nstructural complexity within a unified framework. Furthermore, using this\nkernel and a ridge regression method we can predict atomization energies for a\ndatabase of small organic molecules with a mean absolute error below 1kcal/mol,\nreaching an important milestone in the application of machine-learning\ntechniques to the evaluation of molecular properties."
    },
    {
        "anchor": "Stress field prediction in fiber-reinforced composite materials using a\n  deep learning approach: Computational stress analysis is an important step in the design of material\nsystems. Finite element method (FEM) is a standard approach of performing\nstress analysis of complex material systems. A way to accelerate stress\nanalysis is to replace FEM with a data-driven machine learning based stress\nanalysis approach. In this study, we consider a fiber-reinforced matrix\ncomposite material system and we use deep learning tools to find an alternative\nto the FEM approach for stress field prediction. We first try to predict stress\nfield maps for composite material systems of fixed number of fibers with\nvarying spatial configurations. Specifically, we try to find a mapping between\nthe spatial arrangement of the fibers in the composite material and the\ncorresponding von Mises stress field. This is achieved by using a convolutional\nneural network (CNN), specifically a U-Net architecture, using true stress maps\nof systems with same number of fibers as training data. U-Net is a\nencoder-decoder network which in this study takes in the composite material\nimage as an input and outputs the stress field image which is of the same size\nas the input image. We perform a robustness analysis by taking different\ninitializations of the training samples to find the sensitivity of the\nprediction accuracy to the small number of training samples. When the number of\nfibers in the composite material system is increased for the same volume\nfraction, a finer finite element mesh discretization is required to represent\nthe geometry accurately. This leads to an increase in the computational cost.\nThus, the secondary goal here is to predict the stress field for systems with\nlarger number of fibers with varying spatial configurations using information\nfrom the true stress maps of relatively cheaper systems of smaller fiber\nnumber.",
        "positive": "Enhanced photocatalytic efficiency of layered CdS/CdSe heterostructures:\n  Insights from first principles electronic structure calculations: Metal sulfides are emerging as an important class of materials for\nphotocatalytic applications, because of their high photo responsive nature in\nthe wide visible light range. CdS in this class of materials, have a direct\nband gap of 2.4 eV, have gained special attention due to the relative position\nof its conduction band minimum, which is very close to the energies of the\nreduced protons. However, the photogenerated holes in the valence band of CdS\nare prone to oxidation and destroy its structure during photocatalysis. Thus\nconstructing a CdS based heterostructure would be an effective strategy for\nimproving the photocatalytic performance. In this work we have done a detail\ntheoretical investigation based on hybrid density functional theory calculation\nto get insight into the energy band structure, mobility and charge transfer\nacross the CdS/CdSe heterojunction. The results indicate that CdS/CdSe forms\ntype-II heterostructure that has several advantages in improving the\nphotocatalytic efficiency under visible light irradiation."
    },
    {
        "anchor": "Electron-phonon mediated spin-flip as driving mechanism for ultrafast\n  magnetization dynamics in 3$d$ ferromagnets: Despite intense experimental effort, theoretical proposals and modeling\napproaches, a lack of consensus exists about the intrinsic mechanisms driving\nultrafast magnetization dynamics in 3$d$ ferromagnets. In this work, we find\nevidence of electron-phonon mediated spin-flip as the driving mechanism for the\nultrafast magnetization dynamics in all three 3$d$ ferromagnets; nickel, iron\nand cobalt. We use a microscopic three temperature model with parameters\ncalculated from first-principles, which has been validated by direct comparison\nto the electron and lattice dynamics extracted from previous experiments. By\ndirect comparison to the experimentally measured magnetization dynamics for\ndifferent laser fluence, we determine the spin-flip probability of each\nmaterial. In contrast to previous findings but in agreement to ab-initio\npredictions, we find that relatively small values of the spin-flip probability\nenable ultrafast demagnetization in all three 3$d$ ferromagnets.",
        "positive": "Improving the operational stability of thermoelectric Zn$_4$Sb$_3$ by\n  segmentation: The mixed ionic-electronic conductor $\\beta$-Zn$_4$Sb$_3$ is a cheap and high\nperforming thermoelectric material, but under operating conditions with a\ntemperature gradient and a running current, the material decomposes as Zn\nreadily migrates in the structure. Here, we report an improved stability of\n$\\beta$-Zn$_4$Sb$_3$ by introducing ion-blocking interfaces of stainless steel\nto segment the sample, produced by a rapid one-step Spark Plasma Sintering\nsynthesis. The stability of the samples is tested under temperature gradients\nand electric currents, which reveals significantly improved stability of the\nsegmented samples compared to unsegmented samples. The segmented samples are\nstable under temperature gradient from 250{\\deg}C to room temperature with no\nexternal current, whereas the unsegmented sample decomposes into ZnSb and Zn\nunder the same conditions. The thermoelectric figure of merit, zT, of the\nsegmented sample is slightly reduced, mainly due to the increased thermal\nconductivity. In conclusion, a rapid one-step synthesis of segmented\n$\\beta$-Zn$_4$Sb$_3$ is developed, which successfully improves the long-term\noperational stability by blocking the Zn ion migration."
    },
    {
        "anchor": "A space-time gauge theory for modeling ductile damage and its NOSB\n  peridynamic implementation: Local translational and scaling symmetries in space-time is exploited for\nmodelling ductile damage in metals and alloys over wide ranges of strain rate\nand temperature. The invariant energy density corresponding to the ductile\ndeformation is constructed through the gauge invariant curvature tensor by\nimposing the Weyl like condition. The energetics of the plastic deformation is\nbrought in through the gauge compensating field emerged due to local\ntranslation. Invariance of the energy density under the local action of\ntranslation and scaling is preserved through minimally replaced space-time\ngauge covariant operators. Minimal replacement introduces two non-trivial gauge\ncompensating fields pertaining to local translation and scaling. These are used\nto describe ductile damage, including plastic flow and micro-crack evolution in\nthe material. A space-time pseudo-Riemannian metric is used to lay out the\nkinematics in a finite-deformation setting. Recognizing the available insights\nin classical theories of viscoplasticity, we also establish a correspondence of\nthe gauge compensating field due to spatial translation with Kr\\\"{o}ner's\nmultiplicative decomposition of the deformation gradient. Thermodynamically\nconsistent coupling between viscoplasticity and ductile damage is ensured\nthrough an appropriate degradation function. Non-ordinary state-based (NOSB)\nperidynamics (PD) discretization of the model is used for numerical\nimplementation. The model's viability is tested in reproducing a few\nexperimentally known facts, viz., strain rate locking in the stress-strain\nresponse, whose origin is traced to a nonlinear microscopic inertia term\narising out of the space-time translation symmetry. Finally, we solved 2D and\naxisymmetric deformation problems for qualitatively validating the model's\nviability. NOSB peridynamics axisymmetric formulation in finite deformation\nsetup is also presented.",
        "positive": "Adsorption geometry and electronic structure of iron phthalocyanine on\n  Ag surfaces: A LEED and photoelectron momentum mapping study: We present a comprehensive study of the adsorption behavior of iron\nphthalocyanine on the low-index crystal faces of silver. By combining\nmeasurements of the reciprocal space by means of photoelectron momentum mapping\nand low energy electron diffraction, the real space adsorption geometries are\nreconstructed. At monolayer coverage ordered superstructures exist on all\nstudied surfaces containing one molecule in the unit cell in case of Ag(100)\nand Ag(111), and two molecules per unit cell for Ag(110). The azimuthal tilt\nangle of the molecules against the high symmetry directions of the substrate is\nderived from the photoelectron momentum maps. A comparative analysis of the\nmomentum patterns on the substrates with different symmetry indicates that both\nconstituents of the twofold degenerate FePc lowest unoccupied molecular orbital\nare occupied by charge transfer from the substrate at the interface."
    },
    {
        "anchor": "Pore space analysis of beech wood: the vessel network: Water transport in wood is vital for the survival of trees. With synchrotron\nradiation X-ray tomographic microscopy (SRXTM), it becomes possible to\ncharacterize and quantify the 3D network formed by vessels that are responsible\nfor longitudinal transport. In the present paper, the spatial size dependence\nof vessels and the organization inside single growth rings in terms of vessel\ninduced porosity was studied by SRXTM. Network characteristics, such as\nconnectivity, were deduced by digital image analysis from the processed\ntomographic data and related to known complex network topologies.",
        "positive": "Magnetoresistance in Single Layer Graphene: Weak Localization and\n  Universal Conductance Fluctuation Studies: We report measurements of magnetoresistance in single-layer graphene as a\nfunction of gate voltage (carrier density) at 250 mK. By examining signatures\nof weak localization (WL) and universal conductance fluctuations (UCF), we find\na consistent picture of phase coherence loss due to electron-electron\ninteractions. The gate-dependence of the elastic scattering terms suggests that\nthe effect of trigonal warping, i.e., the non-linearity of the dispersion\ncurves, may be strong at high carrier densities, while intra-valley scattering\nmay dominate close to the Dirac point. In addition, a decrease in UCF amplitude\nwith decreasing carrier density can be explained by a corresponding loss of\nphase coherence."
    },
    {
        "anchor": "Confirmation of the monoclinic Cc space group for the ground state phase\n  of Pb(Zr0.525Ti0.475)O3 (PZT525): A Combined Synchrotron X-Ray and Neutron\n  Powder Diffraction Study: The low temperature antiferrodistortive phase transition in a\npseudo-tetragonal composition of PZT with x=0.525 is investigated through a\ncombined synchrotron x-ray and neutron powder diffraction study. It is shown\nthat the superlattice peaks cannot be correctly accounted for in the Rietveld\nrefinement using R3c or R3c+Cm structural models, whereas the Cc space group\ngives excellent fits to the superlattice peaks as well as to the perovskite\npeaks. This settles at rest the existing controversies about the structure of\nthe ground state phase of PZT in the MPB region.",
        "positive": "Semi-metals as potential thermoelectric materials: case of HgTe: The best thermoelectric materials are believed to be heavily doped\nsemiconductors. The presence of a bandgap is assumed to be essential to achieve\nlarge thermoelectric power factor and figure of merit. In this work, we study\nHgTe as an example semimetal with competitive thermoelectric properties. We\nemploy ab initio calculations with hybrid exchange-correlation functional to\naccurately describe the electronic band structure in conjunction with the\nBoltzmann Transport theory to investigate the electronic transport properties.\nWe show that intrinsic HgTe, a semimetal with large disparity in its electron\nand hole masses, has a high thermoelectric power factor that is comparable to\nthe best known thermoelectric materials. We also calculate the lattice thermal\nconductivity using first principles calculations and evaluate the overall\nfigure of merit. Finally, we prepare semi-metallic HgTe samples and we\ncharacterize their transport properties. We show that our theoretical\ncalculations agree well with the experimental data"
    },
    {
        "anchor": "Cooling power analysis of a small scale 4 K pulse tube cryocooler driven\n  by an oil-free low input power Helium compressor: Here we report the performance of a small scale 4 K pulse tube cryocooler\noperating with a low input power reaching a minimum temperature of 2.2 K, as\nwell as a cooling capacity of over 240 mW at 4.2 K. The compressor is air\ncooled and can be supplied by single phase power sockets. With an input power\nof about 1.3 kW the coefficient of performance reaches values of up to 185\nmW/kW, which is among the highest currently reported values for small to medium\npower pulse tubes. The combination of an oil-free Helium compressor and low\nmaintenance pulse tube cryocooler provides a unique miniaturized, energy\nefficient and mobile cooling tool for applications at 4 K and below.",
        "positive": "Influence of annealing parameters on the ferromagnetic properties of\n  optimally passivated (Ga,Mn)As epilayers: The influence of annealing parameters - temperature and time - on the\nmagnetic properties of As-capped (Ga,Mn)As epitaxial thin films have been\ninvestigated. The dependence of the transition temperature (Tc) on annealing\ntime marks out two regions. The Tc peak behavior, characteristic of the first\nregion, is more pronounced for thick samples, while for the second\n(`saturated') region the effect of the annealing time is more pronounced for\nthin samples. A right choice of the passivation medium, growth conditions along\nwith optimal annealing parameters routinely yield Tc-values of ~ 150 K and\nabove, regardless of the thickness of the epilayers."
    },
    {
        "anchor": "Electron-Phonon Beyond Fr\u00f6hlich: Dynamical Quadrupoles in Polar and\n  Covalent Solids: We include the treatment of quadrupolar fields beyond the Fr\\\"ohlich\ninteraction in the first-principles electron-phonon vertex in semiconductors.\nSuch quadrupolar fields induce long-range interactions that have to be taken\ninto account for accurate physical results. We apply our formalism to Si\n(nonpolar), GaAs, and GaP (polar) and demonstrate that electron mobilities show\nlarge errors if dynamical quadrupoles are not properly treated.",
        "positive": "Electronic Transport in Two-Dimensional Materials: Two-dimensional (2D) materials have captured the attention of the scientific\ncommunity due to the wide range of unique properties at nanometer-scale\nthicknesses. While significant exploratory research in 2D materials has been\nachieved, the understanding of 2D electronic transport and carrier dynamics\nremains in a nascent stage. Furthermore, since prior review articles have\nprovided general overviews of 2D materials or specifically focused on charge\ntransport in graphene, here we instead highlight charge transport mechanisms in\npost-graphene 2D materials with particular emphasis on transition metal\ndichalcogenides and black phosphorus. For these systems, we delineate the\nintricacies of electronic transport including bandstructure control with\nthickness and external fields, valley polarization, scattering mechanisms,\nelectrical contacts, and doping. In addition, electronic interactions between\n2D materials are considered in the form of van der Waals heterojunctions and\ncomposite films. This review concludes with a perspective on the most promising\nfuture directions in this fast-evolving field."
    },
    {
        "anchor": "Room temperature exchange bias in BiFeO3 / Co-Fe bilayers: Thin highly epitaxial BiFeO$_3$ films were prepared on SrTiO$_3$ (100)\nsubstrates by reactive magnetron co-sputtering. Detailed MOKE measurements on\nBiFeO$_3$/Co-Fe bilayers were performed to investigate the exchange bias as a\nfunction of the films thicknesses and Co-Fe stoichiometries. We found a maximum\nexchange bias of H$_{\\mathrm{eb}}$=92 Oe and a coercive field of\nH$_{\\mathrm{c}}$=89 Oe for a 12.5 nm thick BiFeO$_3$ film with a 2 nm thick Co\nlayer. The unidirectional anisotropy is clearly visible in in-plane rotational\nMOKE measurements. AMR measurements reveal a strongly increasing coercivity\nwith decreasing temperature, but no significant change in the exchange bias\nfield.",
        "positive": "Interfaces between buckling phases in Silicene: Ab initio density\n  functional theory calculations: The buckled structure of silicene leads to the possibility of new kinds of\nline defects that separate regions with reversed buckled phases. In the present\nwork we show that these new grain boundaries have very low formation energies,\none order of magnitude smaller than grain boundaries in graphene. These defects\nare stable along different orientations, and they can all be differentiated by\nSTM images. All these defects present local dimerization between the Si atoms,\nwith the formation of $\\pi$-bonds. As a result, these defects are preferential\nadsorption sites when compared to the pristine region. Thus, the combination of\nlow formation energy and higher reactivity of these defects may be cleverly\nused to design new nano-structures embedded in silicene."
    },
    {
        "anchor": "Single-photon emitting diode in silicon carbide: Electrically driven single-photon emitting devices have immediate\napplications in quantum cryptography, quantum computation and single-photon\nmetrology. Mature device fabrication protocols and the recent observations of\nsingle defect systems with quantum functionalities make silicon carbide (SiC)\nan ideal material to build such devices. Here, we demonstrate the fabrication\nof bright single photon emitting diodes. The electrically driven emitters\ndisplay fully polarized output, superior photon statistics (with a count rate\nof $>$300 kHz), and stability in both continuous and pulsed modes, all at room\ntemperature. The atomic origin of the single photon source is proposed. These\nresults provide a foundation for the large scale integration of single photon\nsources into a broad range of applications, such as quantum cryptography or\nlinear optics quantum computing.",
        "positive": "The electronic-structure origin of cation disorder in transition-metal\n  oxides: Cation disorder is an important design criterion for technologically relevant\ntransition-metal (TM) oxides, such as radiation-tolerant ceramics and Li-ion\nbattery electrodes. In this letter, we use a combination of first-principles\ncalculations, normal mode analysis, and band-structure arguments to pinpoint a\nspecific electronic-structure effect that influences the stability of\ndisordered phases. We find that the electronic configuration of a TM ion\ndetermines to which extent the structural energy is affected by site\ndistortions. This mechanism explains the stability of disordered phases with\nlarge ionic radius differences and provides a concrete guideline for the\ndiscovery of novel disordered compositions."
    },
    {
        "anchor": "One-Dimensional Twisted and Tubular Structures of Zinc Oxide by\n  Semiconductor-Catalyzed Vapor-Liquid-Solid Synthesis: The exploration of new catalysts for the vapor-liquid-solid (VLS) synthesis\nof one-dimensional (1-D) materials promises to yield new morphologies and\nfunctionality. Here, we show, for the model ZnO system, that this possible\nusing a semiconductor (Ge) catalyst. In particular, two unusual morphologies\nare described: twisted nanowires and twisted nanotubes, in addition to the\nusual straight nanowires. The twisted nanotubes show large hollow cores and\nsurprisingly high twisting rates (up to 9o/{\\mu}m), which cannot be easily\nexplained through the Eshelby twist model. A combination of ex situ and in situ\ntransmission electron microscopy measurements suggest that the hollow core\nresults from a competition between growth and etching at the Ge-ZnO interface\nduring synthesis. The twisting rate is consistent with a softening of elastic\nrigidity. These results indicate that the use of unconventional, nonmetallic\ncatalysts provide opportunities to synthesize unusual oxide structures with\npotentially useful properties.",
        "positive": "Nanodiamond Collective Electron States and their Localization: The existence and localization of collective electron states for nanodiamond\nparticles were studied both by solving a one-particle one-dimensional\nSchr\\\"odinger equation in the Kronig-Penney potential and by ab initio\ncomputations of ground state wavefunctions of diamondoids C78H64, C123H100 and\nC211H140 at the DFT R-B3LYP/6-31G(d,p) level of theory. Three distinct classes\nof collective electron states have been found: collective bonding orbitals\nresembling the morphology of 3D-modulated particle in a box solutions;\nsurface-localized non-bonding conductive Tamm states and subsurface-localized\nbonding states for non-uniformly compressed nanodiamond. Quantum-mechanical\nanalysis shows that collective unpaired electrons are intrinsic to nanodiamond.\nTheir subsurface localization is described in terms of surface compression\narising from a self-consistency condition of the electron-nuclear wavefunction.\nIntrinsic spin existence is supposed to result from the collective and spread\nnature of subsurface orbitals, allowing spin-density fluctuation effects to\nbecome significant on this length scale. Suggested model allows to explain free\nspins of nanodiamond exhibited in experiments."
    },
    {
        "anchor": "Microstructure Evolution of Solid Oxide Fuel Cell Anodes Characterized\n  by Persistent Homology: Uncovering microstructure evolution mechanisms that accompany the long-term\noperation of solid oxide fuel cells is a fundamental challenge in designing a\nmore durable energy system for the future. To date, the study of fuel cell\nstack degradation has focused mainly on electrochemical performance and, more\nrarely, on averaged microstructural parameters. Here we show an alternative\napproach in which an evolution of three-dimensional microstructural features is\nstudied using electron tomography coupled with topological data analysis. The\nlatter produces persistent images of microstructure before and after long-term\noperation of electrodes. Those images unveil a new insight into the degradation\nprocess of three involved phases: nickel, pores, and yttrium-stabilized\nzirconium.",
        "positive": "Enhancement of TC and reentrant spin-glass transition in\n  La0.86Ca0.14Mn1-yCryO3 (y = 0, 0.1 and 0.2): We report on the structural, frequency dependent ac susceptibility, dc\nmagnetization and magnetoresistance (MR) measurements on polycrystalline\nsamples of La0.86Ca0.14Mn1-yCryO3(y = 0, 0.1 and 0.2) prepared by sol-gel\ntechnique. For y = 0, a paramagnetic to ferromagnetic transition was observed\nat TC = 185 K. For y = 0.1, the value of TC = 200 K, an increase of 15 K and\nfor y = 0.2, the TC = 195 K, an increase of 10 K. The imaginary part of the ac\nsusceptibility of all the three samples shows a secondary transition at Tf <\nTC. For y = 0, there is no definite law to account for the frequency dependence\nof Tf and is attributed to a transition arising out of a canted structure.\nHowever, in the case of y = 0.1 and 0.2, the frequency dependence indicate the\npresence of a reentrant spin glass transition at Tf. Though all the three\nsamples show a semi-conducting behavior between 300 and 5 K, a negative MR was\nobserved corresponding to TC and Tf. The value of MR decreased for the Cr\nsubstituted samples."
    },
    {
        "anchor": "Temperature effect on lattice and electronic structures of WTe$_2$ from\n  first-principles study: Tungsten ditelluride (WTe$_2$) exhibits extremely large and unsaturated\nmagnetoresistance (MR). Due to the large spatially extensions of Te-5p and W-5d\norbitals, the electronic properties of WTe$_2$ are sensitive to the lattice\nstructures, which can probably affect the strongly temperature dependent MR\nfound in experiment. Based on first-principle calculations, we investigate the\ntemperature effect on the lattice and electronic structures of WTe$_2$. Our\nnumerical results show that the thermal expansion coefficients of WTe$_2$ are\nhighly anisotropic and considerably large. However, the temperature (less than\n300 K) has ignorable effect on the Fermi surface of WTe$_2$. Our theoretical\nresults clarify that the thermal expansion is not the main reason of the\ntemperature-induced rapid decrease of magnetoresistance.",
        "positive": "Shear bands in materials processing: Understanding the mechanics of flow\n  localization from Zener's time to the present: Shear banding is a material instability in large strain plastic deformation\nof solids, where otherwise homogeneous flow becomes localized in narrow\nmicrometer-scale bands. Shear bands have broad implications for materials\nprocessing and failure under dynamic loading in a wide variety of material\nsystems ranging from metals to rocks. This year marks 75 years since the\npublication of Zener and Hollomon's pioneering work on shear bands which is\nwidely credited with drawing the attention of the mechanics community to shear\nbands and related localization phenomena. There has since been significant\nexperimental and theoretical investigation into the onset of shear banding.\nYet, given the extremely small length and time scales associated with band\ndevelopment, several challenges persist in studying the evolution of single\nbands. Recent full-field displacement measurements, coupled with numerical\nmodeling, have only begun to ameliorate this problem. This article summarizes\nour present understanding of plastic flow dynamics around single shear bands\nand the subsequent transition to fracture, with special applications to\nmaterials processing. We begin with a semi-historical look at some of Zener's\nearly ideas on shear bands and discuss recent advances in experimental methods\nfor mapping localized flow during band formation, including direct \\emph{in\nsitu} imaging as well as \\emph{ex situ}/post-mortem analyses. Classical\ntheories are revisited in the light of recently published experimental data.\nShear bands exhibit a wealth of complex flow characteristics that bear striking\nresemblance to boundary layer phenomena in fluid flows. It is hoped that these\nwill help further our understanding of shear band dynamics, the subsequent\ntransition to fracture, and lead to practical `control' strategies for\nsuppressing shear band-driven failures in processing applications."
    },
    {
        "anchor": "High-output CPP-GMR sensor with synthetic-ferrimagnet free layer and\n  enhanced spin-torque critical currents: It is shown that the maximum stable output of a CPP-GMR sensor is increased\nsignificantly by using a synthetic ferrimagnet free layer, provided the\nelectron current flows from free layer to reference layer. This free layer\nallows a larger magnetoresistance ratio for a given free layer magnetic moment,\nand in addition results in a greater than three-fold increase in the critical\ncurrent above which spin-torque instability of the free layer occurs. In read\nheads with net free layer moments equivalent to only 4.5nm of Ni80Fe20, this\neffect is shown to result in sustainable sense current densities above 2e8\nA/cm2.",
        "positive": "Magnetoresistance effects in the metallic antiferromagnet Mn$_2$Au: In antiferromagnetic spintronics, it is essential to separate the resistance\nmodifications of purely magnetic origin from other effects generated by current\npulses intended to switch the N\\'eel vector. We investigate the\nmagnetoresistance effects resulting from magnetic field induced reorientations\nof the staggered magnetization of epitaxial antiferromagnetic Mn2Au(001) thin\nfilms. The samples were exposed to 60 T magnetic field pulses along different\ncrystallographic in-plane directions of Mn2Au(001), while their resistance was\nmeasured. For the staggered magnetization aligned via a spin-flop transition\nparallel to the easy [110]-direction, an ansiotropic magnetoresistance of -0.15\n% was measured. In the case of a forced alignment of the staggered\nmagnetization parallel to the hard [100]-direction, evidence for a larger\nanisotropic magnetoresistance effect was found. Furthermore, transient\nresistance reductions of about 1 % were observed, which we associate with the\nannihilation of antiferromagnetic domain walls by the magnetic field pulses."
    },
    {
        "anchor": "Magnetic properties of icosahedral quasicrystals and their cubic\n  approximants in the Cd-Mg-RE (RE = Gd, Tb, Dy, Ho, Er, and Tm) systems: A systematic investigation has been performed to elucidate effects of\nRare-Earth (RE) type and local atomic configuration on magnetic properties of\nicosahedral quasicrystal (iQC) and their cubic approximants (2/1 and 1/1 ACs)\nin the ternary Cd-Mg-RE (RE = Gd, Tb, Dy, Ho, Er, and Tm) systems. At low\ntemperatures, iQC and 2/1 ACs exhibit spin-glass-like freezing for RE = Gd, Tb,\nDy, and Ho, while Er and Tm systems do not show freezing behaviour down to the\nbase temperature ~ 2 K. The 1/1 ACs exhibit either spin-glass-like freezing or\nantiferromagnetic (AFM) ordering depending on their constituent Mg content. The\nTf values show increasing trend from iQC to 2/1 and 1/1 ACs. In contrast, the\nabsolute values of Weiss temperature for iQCs are larger than those in 2/1 and\n1/1 ACs, indicating that the total AFM interactions between the neighboring\nspins are larger in aperiodic, rather than periodic systems. Competing spin\ninteractions originating from the long-range Ruderman-Kittel-Kasuya-Yoshida\nmechanism along with chemical disorder of Cd/Mg ions presumably account for the\nobserved spin-glass-like behavior in Cd-Mg-RE iQCs and ACs.",
        "positive": "libvdwxc: A library for exchange-correlation functionals in the vdW-DF\n  family: We present libvdwxc, a general library for evaluating the energy and\npotential for the family of vdW-DF exchange--correlation functionals. libvdwxc\nprovides an efficient implementation of the vdW-DF method and can be interfaced\nwith various general-purpose DFT codes. Currently, the GPAW and Octopus codes\nimplement interfaces to libvdwxc. The present implementation emphasizes\nscalability and parallel performance, and thereby enables \\textit{ab initio}\ncalculations of nanometer-scale complexes. The numerical accuracy is\nbenchmarked on the S22 test set whereas parallel performance is benchmarked on\nligand-protected gold nanoparticles\n($\\text{Au}_{144}(\\text{SC}_{11}\\text{NH}_{25})_{60}$) up to 9696 atoms."
    },
    {
        "anchor": "Mori-Tanaka Based Estimates of Effective Thermal Conductivity of Various\n  Engineering Materials: The purpose of this paper is to present a simple micromechanics-based model\nto estimate the effective thermal conductivity of real-world macroscopically\nisotropic materials of matrix-inclusion type. The methodology is based on the\nwell-established Mori-Tanaka method for composite media reinforced with\nellipsoidal inclusions, extended to account for imperfect thermal contact at\nthe matrix-inclusion interface, random orientation of particles and particle\nsize distribution. Using simple ensemble averaging arguments, we show that the\noriginal Mori-Tanaka relations are still applicable for these complex systems,\nprovided that the inclusion conductivity is appropriately modified. Such\nconclusion is supported by the verification of the model against a detailed\nfinite-element study as well as its validation against experimental data for a\nwide range of engineering material systems.",
        "positive": "Limitations of mean-field approximations in describing shift-current and\n  injection-current in materials: We theoretically investigate bulk photovoltaic effects, with a specific focus\non shift-current and injection-current. Initially, we perform a numerical\nanalysis of the direct current (dc) induced by a laser pulse with a\none-dimensional model, utilizing mean-field theories such as time-dependent\nHartree--Fock and time-dependent Hartree methods. Our numerical results,\nobtained with mean-field theories, reveal that the dc component of the current\nexists even after irradiation with linearly polarized light as a second-order\nnonlinear effect, indicating the generation of injection current. Conversely,\nwhen we employ the independent particle approximation, no injection current is\ngenerated by linearly polarized light. To develop the microscopic understanding\nof injection current within the mean-field approximation, we further analyze\nthe dc component of the current with the perturbation theory, employing the\nmean-field approximations, the independent-particle approximation, and the\nexact solution of the many-body Schr\\\"odinger equation. The perturbation\nanalysis clarifies that the injection current induced by linearly polarized\nlight under the mean-field approximations is an artifact caused by population\nimbalance, created through quantum interference from unphysical self-excitation\npathways. Therefore, investigation of many-body effects on the bulk\nphotovoltaic effects have to be carefully conducted in mean-field schemes due\nto potential contamination by unphysical dc current. Additionally, we perform\nthe first-principles electron dynamics calculation for BaTiO$_3$ based on the\ntime-dependent density functional theory, and we confirm that the above\nfindings from the one-dimensional model calculation and the perturbation\nanalysis apply to realistic systems."
    },
    {
        "anchor": "Structural, electronic, and dynamical properties of amorphous gallium\n  arsenide: a comparison between two topological models: We present a detailed study of the effect of local chemical ordering on the\nstructural, electronic, and dynamical properties of amorphous gallium arsenide.\nUsing the recently-proposed ``activation-relaxation technique'' and empirical\npotentials, we have constructed two 216-atom tetrahedral continuous random\nnetworks with different topological properties, which were further relaxed\nusing tight-binding molecular dynamics. The first network corresponds to the\ntraditional, amorphous, Polk-type, network, randomly decorated with Ga and As\natoms. The second is an amorphous structure with a minimum of wrong (homopolar)\nbonds, and therefore a minimum of odd-membered atomic rings, and thus\ncorresponds to the Connell-Temkin model. By comparing the structural,\nelectronic, and dynamical properties of these two models, we show that the\nConnell-Temkin network is energetically favored over Polk, but that most\nproperties are little affected by the differences in topology. We conclude that\nmost indirect experimental evidence for the presence (or absence) of wrong\nbonds is much weaker than previously believed and that only direct structural\nmeasurements, i.e., of such quantities as partial radial distribution\nfunctions, can provide quantitative information on these defects in a-GaAs.",
        "positive": "Surface States and Resonances in Field Emission from Low Index Facets of\n  Clean Tungsten: The energies, widths, and shapes of features observed in the total energy\ndistributions in field emission from W(100) and W(111) are compared with the\nresults of a full-potential LAPW calculation of the surface density of states\nbased on a supercell model of the crystal structure at the metal-vacuum\ninterface. The Swanson hump on W(100) is attributed to two bands of surface\nstates and surface resonances of dz^2 symmetry that are highly localised at the\ncenter of the surface Brillouin zone (Gamma_bar), and a second peak observed at\nlower energy is attributed to a band of surface resonances, also of dz^2\nsymmetry, centred at 0.11 A^(-1) along Gamma_bar to X_bar. The energy scale of\nthe calculated total energy distribution is compressed by about 20% relative to\nthe experimental data. The present calculation yields strong evidence that the\nbroad asymmetric peak observed on W(111) is due to emission from a band of\nsurface resonances. Further calculations for W(111) are proposed both to test\nthe accuracy of the band model and to take into account the velocity factor\nthat enters in a calculation of the emission current."
    },
    {
        "anchor": "Electric field control of magnetic phase transitions in Ni3V2O8: We report on the electric field control of magnetic phase transition\ntemperatures in multiferroic Ni3V2O8 thin films. Using magnetization\nmeasurements, we find that the phase transition temperature to the canted\nantiferromagnetic state is suppressed by 0.2 K in an electric field of 30 MV/m,\nas compared to the unbiased sample. Dielectric measurements show that the\ntransition temperature into the magnetic state associated with ferroelectric\norder increases by 0.2 K when the sample is biased at 25 MV/m. This electric\nfield control of the magnetic transitions can be qualitatively understood using\na mean field model incorporating a tri-linear coupling between the magnetic\norder parameters and spontaneous polarization.",
        "positive": "Fe2+:ZnMgSe single crystals, a new material for active elements of\n  tunable lasers for 4-5 mkm: Proposed is a new laser material for the making of active elements of tunable\nlasers for mid IR region (4-5 mkm) - Zn1-xMgxSe (0.11<x<0.42) single crystals\ndoped with Fe2+ ions. The optical transmission spectra of Fe2+:Zn0.89Mg0.11Se\nand Fe2+:Zn0.69Mg0.31Se samples contain strong absorption bands with maxima at\n3.212 and 3.374 mkm, respectively. The generation band maximum of the wide-gap\nsemiconductor laser material Fe2+ :Zn1-xMgxSe shifts towards longer wavelengths\nwith the rise of the concentration of Mg in the crystalline matrix."
    },
    {
        "anchor": "Crystal structure and Raman active lattice vibrations of magnetic\n  topological insulators MnBi2Te4 n(Bi2Te3) (n = 0, 1, . . . , 6): Further to the structure of the intrinsic magnetic topological insulators\nMnBi2Te4 n(Bi2Te3) with n<4, where index n is the number of quintuple\nTe-Bi-Te-Bi-Te building blocks inserted between the neighboring septuple\nTe-Bi-Te-Mn-Te-Bi-Te building blocks, the structure of the members with n=4, 5\nand 6 was studied using X-ray powder diffraction. The unit cell parameters and\natomic positions were calculated. The obtained and available structural data\nwere summarized to show that the crystal structure of all members of MnBi2Te4\nn(Bi2Te3) follows the cubic close packing principle, independently of the space\ngroup of the given member. Confocal Raman spectroscopy was then applied.\nComparative analysis of the number, frequency, symmetry, and broadening of the\nvibration modes responsible for the lines in the Raman spectra of the systems\nwith n=1,. . . ,6, as well as MnBi2Te4 (n=0) and Bi2Te3 (n=infinity) has shown\nthat lattice dynamics of MnBi2Te4 n(Bi2Te3) with n>0 overwhelmingly dominates\nby the cooperative atomic displacements in the quintuple building blocks.",
        "positive": "Thick ferromagnetic films and their anisotropies as described by second\n  order perturbed Heisenberg Hamiltonian: Second and fourth order anisotropy dependence of energy of thick simple cubic\nferromagnetic films with 10000 layers is explained using Heisenberg Hamiltonian\nwith second order perturbation in this manuscript. The second and fourth order\nanisotropy constants were assumed to be constants through out the film. When\nthe fourth order anisotropy is given by fourth order anisotropy of 6, the\nsc(001) ferromagnetic thick films with 10000 layers can be easily oriented in\n0.6 radians direction for the energy parameters given this report. Under the\ninfluence of the second order anisotropy given by second order anisotropy of\n6.3, the easy direction of sc(001) film with 10000 layers is given by 0.66\nradians. Although the energy varies periodically in all cases, the maximum\nenergy considerably decreases with fourth order anisotropy constant. According\nto 3-D plots, energy under influence of second order anisotropy is larger than\nenergy under influence of fourth order anisotropy."
    },
    {
        "anchor": "Machine-learned model Hamiltonian and strength of spin-orbit interaction\n  in strained Mg2X (X = Si, Ge, Sn, Pb): Machine-learned multi-orbital tight-binding (MMTB) Hamiltonian models have\nbeen developed to describe the electronic characteristics of intermetallic\ncompounds $\\rm Mg_2Si, Mg_2Ge, Mg_2Sn$, and $\\rm Mg_2Pb$ subject to strain. The\nMMTB models incorporate spin-orbital mediated interactions and they are\ncalibrated to the electronic band structures calculated via density functional\ntheory (DFT) by a massively parallelized multi-dimensional Monte-Carlo search\nalgorithm. The results show that a machine-learned five-band tight-binding\nmodel reproduces the key aspects of the valence band structures in the entire\nBrillouin zone. The five-band model reveals that compressive strain localizes\nthe contribution of the $3s$ orbital of $\\rm Mg$ to the conduction bands and\nthe outer shell $p$ orbitals of $\\rm X~(X=Si,Ge,Sn,Pb)$ to the valence bands.\nIn contrast, tensile strain has a reversed effect as it weakens the\ncontribution of the $3s$ orbital of $\\rm Mg$ and the outer shell $p$ orbitals\nof $\\rm X$ to the conduction bands and valence bands, respectively. The $\\pi$\nbonding in the $\\rm Mg_2X$ compounds is negligible compared to the $\\sigma$\nbonding components, which follow the hierarchy\n$|\\sigma_{sp}|>|\\sigma_{pp}|>|\\sigma_{ss}|$, and the largest variation against\nstrain belongs to $\\sigma_{pp}$. The five-band model allows for estimating the\nstrength of spin-orbit coupling (SOC) in $\\rm Mg_2X$ and obtaining its\ndependence on the atomic number of $\\rm X$ and strain. Further, the band\nstructure calculations demonstrate a significant band gap tuning and band\nsplitting due to strain. A compressive strain of $-10\\%$ can open a band gap at\nthe $\\Gamma$ point in metallic $\\rm Mg_2Pb$, whereas a tensile strain of\n$+10\\%$ closes the semiconducting band gap of $\\rm Mg_2Si$. A tensile strain of\n$+5\\%$ removes the three-fold degeneracy of valence bands at the $\\Gamma$ point\nin semiconducting $\\rm Mg_2Ge$.",
        "positive": "Tunneling Magnetoresistance in Noncollinear Antiferromagnetic Tunnel\n  Junctions: Antiferromagnetic (AFM) spintronics has emerged as a subfield of spintronics\ndriven by the advantages of antiferromagnets producing no stray fields and\nexhibiting ultrafast magnetization dynamics. The efficient method to detect an\nAFM order parameter, known as the N\\'eel vector, by electric means is critical\nto realize concepts of AFM spintronics. Here, we demonstrate that non-collinear\nAFM metals, such as Mn3Sn, exhibit a momentum dependent spin polarization which\ncan be exploited in AFM tunnel junctions to detect the N\\'eel vector. Using\nfirst-principles calculations based on density functional theory, we predict a\ntunneling magnetoresistance (TMR) effect as high as 300% in AFM tunnel\njunctions with Mn3Sn electrodes, where the junction resistance depends on the\nrelative orientation of their N\\'eel vectors and exhibits four non-volatile\nresistance states. We argue that the spin-split band structure and the related\nTMR effect can also be realized in other non-collinear AFM metals like Mn3Ge,\nMn3Ga, Mn3Pt, and Mn3GaN. Our work provides a robust method for detecting the\nN\\'eel vector in non-collinear antiferromagnets via the TMR effect, which may\nbe useful for their application in AFM spintronic devices."
    },
    {
        "anchor": "Magnetic Properties and Large Coercivity of MnxGa Nanostructures: To investigate structure-property correlations, high-coercivity MnxGa\nnanoparticles were synthesized by the method of sequential deposition of Ga and\nMn fluxes using molecular beam epitaxy. Spontaneous nanostructuring was\nassisted by the use of an Au precursor and thermal annealing, and the growth\nproperties, structure and magnetic properties were characterized. Atomic force\nmicroscopy revealed average particle dimensions of 100 nm and X-ray diffraction\nrevealed a dominant tetragonal D022 crystal structures. Magnetic\ncharacterization at room temperature identified the presence of two magnetic\nphases, dominated by a high-coercivity (2.3 T) component in addition to a\nlow-coercivity component.",
        "positive": "Operando optical tracking of single-particle ion dynamics and phase\n  transitions in battery electrodes: Key to advancing lithium-ion battery technology, and in particular fast\ncharging capabilities, is our ability to follow and understand the dynamic\nprocesses occurring in operating materials under realistic conditions, in real\ntime, and on the nano- to meso-scale. Currently, operando imaging of\nlithium-ion dynamics requires sophisticated synchrotron X-ray or electron\nmicroscopy techniques, which do not lend themselves to high-throughput material\nscreening. This limits rapid and rational materials improvements. Here we\nintroduce a simple lab-based, optical interferometric scattering microscope to\nresolve nanoscopic lithium-ion dynamics in battery materials and apply it to\nfollow the repeated cycling of the archetypical cathode material\nLi$_\\textit{x}$CoO$_2$. The method allows us to visualise directly the\ninsulator-metal, solid solution and lithium ordering phase transitions in this\nmaterial. We determine rates of lithium insertion and removal at the\nsingle-particle level and identify different mechanisms that occur on charge\nvs. discharge. Finally, we capture the dynamic formation of domain boundaries\nbetween different crystal orientations associated with the monoclinic lattice\ndistortion at around Li$_{0.5}$CoO$_2$. The high throughput nature of our\nmethodology allows many particles to be sampled across the entire electrode\nand, moving forward, will enable exploration of the role of dislocations,\nmorphologies and cycling rate on battery degradation. The generality of our\nimaging concept means that it can be applied to study any battery electrode,\nand more broadly, systems where the transport of ions is associated with\nelectronic or structural changes, including nanoionic films, ionic conducting\npolymers, photocatalytic materials and memristors."
    },
    {
        "anchor": "Singlet-triplet splitting, correlation and entanglement of two electrons\n  in quantum dot molecules: Starting with an accurate pseudopotential description of the single-particle\nstates, and following by configuration-interaction treatment of correlated\nelectrons in vertically coupled, self-assembled InAs/GaAs quantum\ndot-molecules, we show how simpler, popularly-practiced approximations, depict\nthe basic physical characteristics including the singlet-triplet splitting,\ndegree of entanglement (DOE) and correlation. The mean-field-like\nsingle-configuration approaches such as Hartree-Fock and local spin density,\nlacking correlation, incorrectly identify the ground state symmetry and give\ninaccurate values for the singlet-triplet splitting and the DOE. The Hubbard\nmodel gives qualitatively correct results for the ground state symmetry and\nsinglet-triplet splitting, but produces significant errors in the DOE because\nit ignores the fact that the strain is asymmetric even if the dots within a\nmolecule are identical. Finally, the Heisenberg model gives qualitatively\ncorrect ground state symmetry and singlet-triplet splitting only for rather\nlarge inter-dot separations, but it greatly overestimates the DOE as a\nconsequence of ignoring the electron double occupancy effect.",
        "positive": "Skyrmions in thin films with easy-plane magnetocrystalline anisotropy: We demonstrate that chiral skyrmionic magnetization configurations can be\nfound as the minimum energy state in B20 thin film materials with easy-plane\nmagnetocrystalline anisotropy with an applied magnetic field perpendicular to\nthe film plane. Our observations contradict results from prior analytical work,\nbut are compatible with recent experimental investigations. The size of the\nobserved skyrmions increases with the easy-plane magnetocrystalline anisotropy.\nWe use a full micromagnetic model including demagnetization and a\nthree-dimensional geometry to find local energy minimum (metastable)\nmagnetization configurations using numerical damped time integration. We\nexplore the phase space of the system and start simulations from a variety of\ninitial magnetization configurations to present a systematic overview of\nanisotropy and magnetic field parameters for which skyrmions are metastable and\nglobal energy minimum (stable) states."
    },
    {
        "anchor": "Probing surface recombination velocities in semiconductors using\n  two-photon microscopy: The determination of minority-carrier lifetimes and surface recombination\nvelocities is essential for the development of semiconductor technologies such\nas solar cells. The recent development of two-photon time-resolved microscopy\nallows for better measurements of bulk and subsurface interfaces properties.\nHere we analyze the diffusion problem related to this optical technique. Our\nthree-dimensional treatment enables us to separate lifetime (recombination)\nfrom transport effects (diffusion) in the photoluminescence intensity. It also\nallows us to consider surface recombination occurring at a variety of\ngeometries: a single plane (representing an isolated exposed or buried\ninterface), two parallel planes (representing two inequivalent interfaces), and\na spherical surface (representing the enclosing surface of a grain boundary).\nWe provide fully analytical results and scalings directly amenable to data\nfitting, and apply those to experimental data collected on heteroepitaxial\nCdTe/ZnTe/Si.",
        "positive": "Changes in polarization dictate necessary approximations for modeling\n  electronic de-excitation intensity: an application to X-ray emission: We systematically investigate the underlying relations among different levels\nof approximation for simulating electronic de-excitations, with a focus on\nmodeling X-ray emission spectroscopy (XES). Using Fermi's golden rule and\nexplicit modeling of the initial, core-excited state and the final,\nvalence-hole state, we show that XES can be accurately modeled by using orbital\noptimization for the various final states within a Slater-determinant\nframework. However, in this paper, we introduce a much cheaper approach reliant\nonly on a single self-consistent field for all the final states, and show that\nit is typically sufficient. Further approximations reveal that these\nfundamentally many-body transitions can be reasonably approximated by\nprojections of ground state orbitals, but that the ground state alone is\ninsufficient. Furthermore, except in cases where the core-ionization induces\nnegligible changes in polarization, linear-response approaches within the\nadiabatic approximation will have difficulty in accurately modeling\nde-excitation to the core level. Therefore, change in the net dipole moment of\nthe valence electrons can serve as a metric for the validity of the\nlinear-response approximation."
    },
    {
        "anchor": "Data-driven study of composition-dependent phase compatibility in NiTi\n  shape memory alloys: The martensitic transformation in NiTi-based Shape Memory Alloys (SMAs)\nprovides a basis for shape memory effect and superelasticity, thereby enabling\napplications requiring solid-state actuation and large recoverable shape\nchanges upon mechanical load cycling. In order to tailor the transformation to\na particular application, the compositional dependence of properties in\nNiTi-based SMAs, such as martensitic transformation temperatures and\nhysteresis, has been exploited. However, the compositional design space is\nlarge and complex, and experimental studies are expensive. In this work, we\ndevelop an interpretable piecewise linear regression model that predicts the\n$\\lambda_2$ parameter, a measure of compatibility between austenite and\nmartensite phases, and an (indirect) factor that is well-correlated with\nmartensitic transformation hysteresis, based on the chemical features derived\nfrom the alloy composition. The model is capable of predicting, for the first\ntime, the type of martensitic transformation for a given alloy chemistry. The\nproposed model is validated by experimental data from the literature as well as\nin-house measurements. The results show that the model can effectively\ndistinguish between $B19$ and $B19^{\\prime}$ regions for any given composition\nin NiTi-based SMAs and accurately estimate the $\\lambda_2$ parameter. Our\nanalysis also reveals that the weighted average of the quotient of the first\nionization energy and the Voronoi coordination number is a key compositional\ncharacteristic that correlates with the $\\lambda_2$ parameter and thermodynamic\nresponses, including the transformation hysteresis, martensite start\ntemperature, and critical temperature. The work herein demonstrates the\npotential of data-driven methodologies for understanding and designing\nNiTi-based SMAs with desired transformation characteristics.",
        "positive": "Diffusion and transformation kinetics of small Helium clusters in bulk\n  Tungsten: The production of energy through nuclear fusion poses serious challenges\nrelated to the stability and performance of materials in extreme conditions. In\nparticular, the constant bombardment of the walls of the reactor with high\ndoses of He ions is known to lead to deleterous changes in their\nmicrostructures. These changes follow from the aggregation of He into bubbles\nthat can grow and blister, potentially leading to the contamination of the\nplasma, or to the degradation of their mechanical properties. We\ncomputationally study the behavior of small clusters of He atoms in W in\nconditions relevant to fusion energy production. Using a wide range of\ntechniques, we investigate the thermodynamics of the clusters and their\nkinetics in terms of diffusivity, growth, and breakup, as well as mutation into\nnano-bubbles. Our study provides the essential ingredients to model the early\nstages of He exposure leading up to the nucleation of He bubbles."
    },
    {
        "anchor": "On-chip artificial magnon-polariton device for voltage control of\n  electromagnetically induced transparency: We demonstrate an on-chip device utilizing the concept of artificial cavity\nmagnon-polariton (CMP) coupling between the microwave cavity mode and the\ndynamics of the artificial magnetism in a split ring resonator. This on-chip\ndevice allows the easy tuning of the artificial CMP gap by using a DC voltage\nsignal, which enables tuneable electrodynamically induced transparency. The\nhigh tunability of the artificial magnon-polariton system not only enables the\nstudy of the characteristic phenomena associated with distinct coupling\nregimes, but also may open up avenues for designing novel microwave devices and\nultra-sensitive sensors.",
        "positive": "Ta2NiSe5: a candidate topological excitonic insulator with multiple band\n  inversions: The electronic structures and topological properties of the orthorhombic and\nmonoclinic phases of the quasi-one-dimensional excitonic insulator Ta2NiSe5 are\ninvestigated based on density functional theory. In contrast to a single parity\nor band inversion across the Fermi level in many topological insulators studied\npreviously, there are multiple parity and band inversions with or without\nspin-orbit coupling in both phases of Ta2NiSe5, resulting in more complex and\ntopologically nontrivial electronic structures. The Dirac cone type surface\nstates of the low-temperature monoclinic phase are also obtained. In this\npaper, we demonstrate that Ta2NiSe5 is a promising candidate as a\nthree-dimensional topological excitonic insulator."
    },
    {
        "anchor": "Precise Determination of Minimum Achievable Temperature for Solid-State\n  Optical Refrigeration: We measure the minimum achievable temperature (MAT) as a function of\nexcitation wavelength in anti-Stokes fluorescence cooling of high purity\nYb3+-doped LiYF4 (Yb:YLF) crystal. Such measurements were obtained by\ndeveloping a sensitive noncontact thermometry that is based on a two-band\ndifferential luminescence spectroscopy using balanced photo-detectors. These\nmeasurements are in excellent agreement with the prediction of the laser\ncooling model and identify MAT of 110 K at 1020 nm, corresponding to E4-E5\nStark manifold transition in Yb:YLF crystal.",
        "positive": "Pressure-induced Phonon Softenings and the Structural and Magnetic\n  Transitions in CrO$_{2}$: To investigate the pressure-induced structural transitions of chromium\ndioxide (CrO$_{2}$), phonon dispersions and total energy band structures are\ncalculated as a function of pressure. The first structural transition has been\nconfirmed at P$\\approx$ 10 GPa from the ground state tetragonal CrO$_{2}$\n(t-CrO$_{2}$) of rutile type to orthorhombic CrO$_{2}$ (o-CrO$_{2}$) of\nCaCl$_{2}$ type. The half-metallic property is found to be preserved in\no-CrO$_{2}$. The softening of Raman-active B$_{1g}$ phonon mode, which is\nresponsible for this structural transition, is demonstrated. The second\nstructural transition is found to occur for P$\\geq$ 61.1 GPa from ferromagnetic\n(FM) o-CrO$_{2}$ to nonmagnetic (NM) monoclinic CrO$_{2}$ (m-CrO$_{2}$) of\nMoO$_{2}$ type, which is related to the softening mode at {\\bf q} =\nR(1/2,0,1/2). The third structural transition has been newly identified at P=\n88.8 GPa from m-CrO$_{2}$ to cubic CrO$_{2}$ of CaF$_{2}$ type that is a FM\ninsulator."
    },
    {
        "anchor": "Magnetostrictive hysteresis of TbCo/CoFe multilayers and magnetic\n  domains: Magnetic and magnetostrictive hysteresis loops of TbCo/CoFe multilayers under\nfield applied along the hard magnetization axis are studied using vectorial\nmagnetization measurements, optical deflectometry and magneto optical Kerr\nmicroscopy. Even a very small angle misalignment between hard axis and magnetic\nfield direction is shown to drastically change the shape of magnetization and\nmagnetostrictive torsion hysteresis loops. Two kinds of magnetic domains are\nrevealed during the magnetization: big regions with opposite rotation of\nspontaneous magnetization vector and spontaneous magnetic domains which appear\nin a narrow field interval and provide an inversion of this rotation.\n  We show that the details of the hysteresis loops of our exchange-coupled\nfilms can be described using the classical model of homogeneous magnetization\nrotation of single uniaxial films and the configuration of observed domains.\nThe understanding of these features is crucial for applications (for MEMS or\nmicroactuators) which benefit from the greatly enhanced sensitivity near the\npoint of magnetic saturation at the transverse applied field.",
        "positive": "Ab initio study of energetics and structures of heterophase interfaces:\n  from coherent to semicoherent interfaces: Density functional theory calculations have been performed to study the\nstructures and energetics of coherent and semicoherent TiC/Fe interfaces. A\nsystematic method for determining the interfacial energy for the semicoherent\ninterface with misfit dislocation network has been developed. The obtained\ninterfacial energies are used to calculate the aspect ratios for the disc-like\nprecipitates and a quantitative agreement with the experimental results is\nreached. Based on the obtained interfacial energies and atomic structure\ndetails, we propose models for describing the evolution of the interfacial\nenergy with respect to the size of TiC precipitate for heterogeneous nucleation\non an edge dislocation, shedding light on the thermodynamics of precipitate\nnucleation and growth. The present method can be easily applied to any\nheterophase interfaces between metals and oxides/carbides/nitrides."
    },
    {
        "anchor": "Inversion Domain Boundaries in Wurzite GaN: We present two models for the atomic structure of inversion domain boundaries\nin wurzite GaN, that have not been discussed in existing literature. Using\ndensity functional theory, we find that one of these models has a lower\nformation energy than a previously proposed model known as Holt-$IDB$. Although\nthis newly proposed model has a formation energy higher that the accepted lower\nenergy structure, known as $IDB^*$, we argue that it can be formed under\ntypical growth conditions. We present evidence that it may have been already\nobserved in experiments, albeit misidentified as Holt-$IDB$. Our analysis was\nfacilitated by a convenient notation, that we introduced, to characterize these\nmodels; it is based on the mismatch in crystal stacking sequence across the\n$\\{10\\overline{1}0\\}$ plane. Additionally, we introduce an improved method to\ncalculate energies of certain domain walls that challenge the periodic boundary\nconditions needed for plane-wave density functional theory methods. This new\nmethod provides improved estimations of domain wall energies.",
        "positive": "Surface Van Hove Singularity Enabled Efficient Catalysis: The Cases of\n  CO Oxidation and Hydrogen Evolution Reactions: Surface Van Hove singularity (SVHS), defined as the surface states near the\nFermi level (EF) in low-dimensional systems, triggers exciting physical\nphenomena distinct from bulk. We herein explore theoretically the potential\nrole of SVHS in catalysis taking CO oxidation reaction as prototype over\ngraphene/Ca2N (Gra/Ca2N) heterojunction and Pt2HgSe3 (001) surface. It is\ndemonstrated that both systems with SVHS could serve as an electron bath to\npromote O2 adsorption and subsequent CO oxidation with low energy barriers of\n0.2 ~ 0.6 eV for Gra/Ca2N and Pt2HgSe3 (001) surface. Importantly, the\ncatalytically active sites associated with SVHS are well-defined and uniformly\ndistributed over the whole surface plane, which is superior to the commonly\nadopted defect or doping strategy, and further the chemical reactivity of SVHS\nalso can be tuned easily via adjusting its position with respect to EF. Our\nstudy demonstrates the enabling power of SVHS, and provides novel physical\ninsights into the promising potential role of VHS in designing high-efficiency\ncatalysts."
    },
    {
        "anchor": "Negative thermal expansion near the precipice of structural stability in\n  open perovskites: Negative thermal expansion (NTE) describes the anomalous propensity of\nmaterials to shrink when heated. Since its discovery, the NTE effect has been\nfound in a wide variety of materials with an array of magnetic, electronic and\nstructural properties. In some cases, the NTE originates from phase competition\narising from the electronic or magnetic degrees of freedom but we here focus on\na particular class of NTE which originates from intrinsic dynamical origins\nrelated to the lattice degrees of freedom, a property we term\n\\textit{structural} negative thermal expansion (SNTE). Here we review some\nselect cases of NTE which strictly arise from anharmonic phonon dynamics, with\na focus on open perovskite lattices. We find that NTE is often present close in\nproximity to competing structural phases, with structural phase transition\nlines terminating near $T$=0 K yielding the most superlative displays of the\nSNTE effect. We further provide a theoretical model to make precise the\nproposed relationship among the signature behavior of SNTE, the proximity of\nthese systems to structural quantum phase transitions and the effects of phase\nfluctuations near these unique regions of the structural phase diagram. The\neffects of compositional disorder on NTE and structural phase stability in\nperovskites are discussed.",
        "positive": "Cluster Generation Under Pulsed Laser Ablation Of Compound\n  Semiconductors: A comparative experimental study of pulsed laser ablation in vacuum of two\nbinary semiconductors, zinc oxide and indium phosphide, has been performed\nusing IR-and visible laser pulses with particular attention to cluster\ngeneration. Neutral and cationic Zn\\_n O\\_m and In\\_n P\\_m particles of various\nstoichiometry have been produced and investigated by time-of-flight mass\nspectrometry. At ZnO ablation, large cationic (n>9) and all neutral clusters\nare mainly stoichiometric in the ablation plume. In contrast, indium phosphide\nclusters are strongly indium-rich with In\\_4 P being a magic cluster. Analysis\nof the plume composition upon laser exposure has revealed congruent\nvaporization of ZnO and a disproportionate loss of phosphorus by the irradiated\nInP surface. Plume expansion conditions under ZnO ablation are shown to be\nfavourable for stoichiometric cluster formation. A delayed vaporization of\nphosphorus under InP ablation has been observed that results in generation of\noff-stoichiometric clusters."
    },
    {
        "anchor": "Micromagnetic Simulations for Spin Transfer Torque in Magnetic\n  Multilayers: We investigate the spin transfer torque (STT) in the magnetic multilayer\nstructures with micromagnetic simulations. We implement the STT contribution\nfor the magnetic multilayer structures in addition to the\nLandau-Lifshitz-Gilbert (LLG) micromagnetic simulators. Not only the Sloncewski\nSTT term, the zero, first, and second order field- like terms are also\nconsidered, and the effects of the Oersted field by the current are addressed.\nWe determine the switching current densities of the free layer with the\nexchange biased synthetic ferrimagnetic reference layers for various cases.",
        "positive": "Effective-medium theory for infinite-contrast, 2D-periodic, linear\n  composites with strongly anisotropic matrix behavior: dilute limit and\n  cross-over behavior: The overall behavior of a 2D lattice of voids embedded in an anisotropic\nmatrix is investigated in the limit of vanishing porosity f. An\neffective-medium model (of the Hashin-Shtrikman type) which accounts for\nelastic interactions between neighboring voids, is compared to Fast Fourier\nTransform numerical solutions and, in the limits of infinite anisotropy, to\nexact results. A cross-over between regular and singular dilute regimes is\nfound, driven by a characteristic length which depends on f and on the\nanisotropy strength. The singular regime, where the leading dilute correction\nto the elastic moduli is an O(f^{1/2}), is related to strain localization and\nto change in character - from elliptic to hyperbolic - of the governing\nequations."
    },
    {
        "anchor": "Prediction Of A Multi-Center Bonded Solid Boron Hydride for Hydrogen\n  Storage: An ideal material for on-board hydrogen storage must release hydrogen at\npractical temperature and pressure and also regenerate efficiently under\nsimilarly gentle conditions. Therefore, thermodynamically, the hydride material\nmust lie within a narrow range near the hydrogenation/dehydrogenation phase\nboundary. Materials involving only conventional bonding mechanisms are unlikely\nto meet these requirements. In contrast, materials containing certain\nfrustrated bonding are designed to be on the verge of frustration-induced phase\ntransition, and they may be better suited for hydrogen storage. Here we propose\na novel layered solid boron hydride and show its potential for hydrogen\nstorage. The absence of soft phonon modes confirms the dynamical stability of\nthe structure. Charging the structure significantly softens hydrogen-related\nphonon modes. Boron-related phonons, in contrast, are either hardened or not\nsignificantly affected by electron doping. These results suggest that\nelectrochemical charging may facilitate hydrogen release while the underlying\nboron network remains intact for subsequent rehydrogenation.",
        "positive": "Topology-dependent conjugation effects in graphdiyne molecular fragments: Graphdiynes (GDYs) as two-dimensional carbon structures based on sp2\nhybridized aromatic rings connected by sp-hybridized acetylenic linear links\nare gathering an increasing popularity, both for their peculiar properties and\nfor the promising applications. In these materials, structural features affect\nthe degree of pi-electron conjugation resulting in different electronic,\noptical and vibrational properties. In particular, how topology, connectivity\nbetween sp and sp2 domains and system size are related with the final\nproperties is fundamental to understand structure-property relationships and to\ntailor the properties by proper structure design. By using a computational\napproach based on density functional theory calculations, we here investigate\nstructure-property relations in a class of 1D and 2D GDY molecular fragments as\nbuilding block models of extended structures. By analysing how the structure\ncan modulate the pi-electron conjugation in these systems, HOMO-LUMO gap is\nfound to depend on the peculiar topology and connections between linear sp\ndomains and aromatic units. A topological indicator is computed, showing a\ntrend with the gap and with the frequency of the main vibrational mode\noccurring in Raman spectra. Our findings can contribute to guide the molecular\ndesign of new GDY-based sp-sp2 carbon materials, aiming at tuning their\nproperties by precise control of the structure."
    },
    {
        "anchor": "Impact of finite temperatures on the transport properties of Gd from\n  first principles: Finite temperature effects have a pronounced impact on the transport\nproperties of solids. In magnetic systems, besides the scattering of conduction\nelectrons by impurities and phonons, an additional scattering source coming\nfrom the magnetic degrees of freedom must be taken into account. A\nfirst-principle scheme which treats all these scattering effects on equal\nfooting was recently suggested within the framework of the multiple scattering\nformalism. Employing the alloy analogy model treated by means of the CPA,\nthermal lattice vibrations and spin fluctuations are effectively taken into\naccount. In the present work the temperature dependence of the longitudinal\nresistivity and the anomalous Hall effect in the strongly correlated metal Gd\nis considered. The comparison with experiments demonstrates that the proposed\nnumerical scheme does provide an adequate description of the electronic\ntransport at finite temperatures.",
        "positive": "The stress tensor in Thermodynamics and Statistical Mechanics: We prove that the stress tensor, tau^{ab}, of a molecular system with\narbitrary, short-range interactions can be point-wisely expressed as the\nfunctional derivative of the partition function with respect to the local\ndeformation tensor. In this approach the set of components of tau^{ab} has a\nsimple interpretation as the set of Lagrangian multipliers which need to be\nintroduced to enforce the conditions relating point particle displacements to\nthe body local deformation tensor. The question of the non-uniqueness of the\nformula for tau^{ab} is discussed."
    },
    {
        "anchor": "Spontaneous creation and annihilation dynamics and strain-limited\n  stability of magnetic skyrmions: Magnetic skyrmions are topological magnetic spin structures exhibiting\nparticle-like behaviour. They are of strong interest from a fundamental\nviewpoint and for application, where they have potential to act as information\ncarriers in future low-power computing technologies. Importantly, skyrmions\nhave high physical stability because of topological protection. However, they\nhave potential to deform according to their local energy environment. Here we\ndemonstrate that, in regions of high exchange energy density, skyrmions may\nexhibit such extreme deformation that spontaneous merging with nearest\nneighbours or spawning new skyrmions is favoured to attain a lower energy\nstate. Using transmission electron microscopy and a high-speed imaging\ndetector, we observe dynamics involving distinct configurational states, in\nwhich transitions are accompanied by spontaneous creation or annihilation of\nskyrmions. These observations raise important questions regarding the limits of\nskyrmion stability and topological charge conservation, while also suggesting a\nmeans of control of skyrmion creation and annihilation.",
        "positive": "2D graphitic-like gallium nitride and structural selectivity in\n  confinement at graphene/SiC interface: Predictive first-principles calculations suggest graphitic-like GaN to be\ntheoretically possible. Thus far, it has not been experimentally reported. We\nreport on GaN monolayer in a buckled geometry obtained in confinement at\ngraphene/SiC interface by metalorganic chemical vapor deposition (MOCVD).\nConductive atomic force microscopy (C-AFM) has been employed to probe vertical\ncurrent injection through the graphene/SiC interface and to establish the\nuniformity of the intercalated areas. Scanning transmission electron microscopy\n(S/TEM) has been employed for atomic resolution imaging and spectroscopy.\nDiscontinuity in the anticipated stacking sequence of graphitic-like GaN\nmonolayers has been exposed and reasoned as a case of simultaneous formation of\nGa-N and Ga-O bonds. The formation of Ga-O bonds acquires importance in\ninstigating chemical-species-specific structural selectivity in confinement at\natom-size scale."
    },
    {
        "anchor": "Proton Irradiation Induced Defects in \\b{eta}-Ga2O3: a combined EPR and\n  Theory Study: Proton irradiation of both n-type and semi-insulating bulk samples of\n\\b{eta}-Ga2O3 leads to the formation of one paramagnetic defect with spin\nS=1/2, monoclinic point symmetry, a g-tensor with principal values of\ngb=2.0313, gc=2.0079, ga*= 2.0025 and quasi isotropic superhyperfine\ninteraction of 13G with two equivalent Ga neigbours. Its high introduction rate\nindicates it to be a primary irradiation induced defect. At low temperature,\nphotoexcitation transforms this defect into a different metastable S=1/2 center\nwith principal g-values of gb=2.0064, gc=2.0464, ga*= 2.0024 and a reduced\nhyperfine interaction of 9G. This metastable defect is stable up to T=100K,\nwhen it switches back to the previous configuration. Density functional theory\ncalculations of the Spin Hamiltonian parameters of various intrinsic defects\nare carried out using the Gauge Including Projector Augmented Wave method in\norder to determine the microscopic structure of these defects.Our results do\nnot support the intuitive model of the isolated octahedral or tetrahedral\ngallium vacancy, VGa2-, but favor the model of a gallium vacancy complex\nVGa-Gai-VGa.",
        "positive": "Towards Magnonic Logic and Neuromorphic Computing: Controlling\n  Spin-Waves by Spin-Polarized Current: Spin-waves (magnons) are among the prime candidates for building fast yet\nenergy-efficient platforms for information transport and computing. We here\ndemonstrate theoretically and in state-of-the-art micromagnetic simulation the\neffects that strategically-injected spin-polarized current can have on\ncontrolling magnonic transport. We reveal analytically that the Zhang-Li\nspin-transfer-torque induced by applied current is analogous to the\nDzyaloshinskii-Moriya interaction for scattering the magnons in the linear\nregime, to then provide a generalized Snell's law that describes the spin-wave\npropagation across regions with different current densities. We validate the\nlatter in numerical simulations of realistic systems, and exemplify how these\nfindings may help advance the design of spin-wave logic and neuromorphic\ncomputing devices."
    },
    {
        "anchor": "Exploring electronic, optical, and phononic properties of MgX (X=C, N,\n  and O) monolayers using first principle calculations: The electronic, the thermal, and the optical properties of hexagonal MgX\nmonolayers (where X=C, N, and O) are investigated via first principles studies.\nAb-initio molecular dynamic, AIMD, simulations using NVT ensembles are\nperformed to check the thermodynamic stability of the monolayers. We find that\nan MgO monolayer has semiconductor properties with a good thermodynamic\nstability, while the MgC and the MgN monolayers have metallic characters. The\ncalculated phonon band structures of all the three considered monolayers shows\nno imaginary nonphysical frequencies, thus indicating that they all have\nexcellent dynamic stability. The MgO monolayer has a larger heat capacity then\nthe MgC and the MgN monolayers. The metallic monolayers demonstrate optical\nresponse in the IR as a consequence of the metal properties, whereas the\nsemiconducting MgO monolayer demonstrates an active optical response in the\nnear-UV region. The optical response in the near-UV is beneficial for\nnanoelectronics and photoelectric applications. A semiconducting monolayer is a\ngreat choice for thermal management applications since its thermal properties\nare more attractive than those of the metallic monolayer in terms of heat\ncapacity, which is related to the change in the internal energy of the system.",
        "positive": "On the role of confinement on solidification in pure materials and\n  binary alloys: We use a phase-field model to study the effect of confinement on dendritic\ngrowth, in a pure material solidifying in an undercooled melt, and in the\ndirectional solidification of a dilute binary alloy. Specifically, we observe\nthe effect of varying the vertical domain extent ($\\delta$) on tip selection,\nby quantifying the dendrite tip velocity and curvature as a function of\n$\\delta$, and other process parameters. As $\\delta$ decreases, we find that the\noperating state of the dendrite tips becomes significantly affected by the\npresence of finite boundaries. For particular boundary conditions, we observe a\nswitching of the growth state from 3-D to 2-D at very small $\\delta$, in both\nthe pure material and alloy. We demonstrate that results from the alloy model\ncompare favorably with those from an experimental study investigating this\neffect."
    },
    {
        "anchor": "Investigation of thermal stability of hydrogenated amorphous Si/Ge\n  multilayers: Thermal stability of hydrogenated amorphous Si/Ge multilayers has been\ninvestigated by Scanning Electron Microscopy (SEM), Transmission Electron\nMicroscopy (TEM) and Small-Angle X-Ray Diffraction (SAXRD) techniques.\nAmorphous H-Si/Ge multilayers were prepared by RF sputtering with 1.5 and 6\nml/min H2 flow-rate. It is shown by Elastic Recoil Detection Analysis (ERDA)\nthat the hydrogen concentration increased by increasing H2 flow-rate. Annealing\nof the samples was carried out at 400 and 450 oC for several hours. It has been\nobserved that samples prepared with 6 ml/min flow-rate at both annealing\ntemperatures underwent significant structural changes: the surface of the\nsamples was visibly roughened, gas bubbles were formed and craters were\ncreated. The decay of the periodic structure of Si and Ge layers in these types\nof multilayers was faster than in non-hydrogenated samples. Samples prepared\nwith 1.5 ml/min flow-rate have similar behaviour at 450 oC, but at 400 oC the\ndecay of the first order SAXRD peaks was slower than in case of the\nnon-hydrogenated multilayers. Qualitatively the observed behaviour can be\nexplained by the fast desorption of the saturated hydrogen, leading to the\nformation of bubbles and craters at 450 oC, as well as, at 400oC in the sample\nwith lower H-content, by the possible passivation of the dangling bonds\nresulting in a slowing down of the diffusion intermixing.",
        "positive": "A Layered Spin 1/2 polymorph of titanium triiodide: A previously unreported layered spin 1/2 triangular lattice polymorph of TiI3\nis described, synthesized under 6 GPa of applied pressure at 900 C, but stable\nat atmospheric pressure. This air-sensitive material has a CdI2-type layered\nstructure (P-3m1 (#164), a = 4.012 A and c = 6.641 A at 120 K, Z = 1 of\nTi0.667I2) with an in-plane triangular lattice, related to that of TiI4\n(Ti0.5I2). Although the TiI3 formula is consistent with expectations for a\nlayered honeycomb lattice of spin 1/2 Ti(III), there appears to be disorder in\nthe crystal structure. Magnetic susceptibility and heat capacity measurements\nsuggest that the material undergoes several low temperature phase transitions."
    },
    {
        "anchor": "Ultrafast X-ray Diffraction Thermometry Measures the Influence of Spin\n  Excitations on the Heat Transport through nanolayers: We investigate the heat transport through a rare earth multilayer system\ncomposed of Yttrium (Y), Dysprosium (Dy) and Niobium (Nb) by ultrafast X-ray\ndiffraction. This is an example of a complex heat flow problem on the\nnanoscale, where several different quasi-particles carry the heat. The Bragg\npeak positions of each layer represent layer-specific thermometers that measure\nthe energy flow through the sample after excitation of the Y top-layer with\nfs-laser pulses. In an experiment-based analytic solution to the nonequilibrium\nheat transport problem, we derive the individual contributions of the spins and\nthe coupled electron-lattice system to the heat conduction. The full\ncharacterization of the spatiotemporal energy flow at different starting\ntemperatures reveals that the spin excitations of antiferromagnetic Dy speed up\nthe heat transport into the Dy layer at low temperatures, whereas the heat\ntransport through this layer and further into the Y and Nb layers underneath is\nslowed down. The experimental findings are compared to the solution of the heat\nequation using macroscopic temperature-dependent material parameters without\nseparation of spin- and phonon contributions to the heat. We explain, why the\nsimulated energy density matches our experiment-based derivation of the heat\ntransport, although the simulated thermoelastic strain in this simulation is\nnot even in qualitative agreement.",
        "positive": "Oriented Asymmetric Wave Propagation and Refraction Bending in\n  Hyperbolic Media: Crystal quartz is a well-known anisotropic medium with optically active\nphonons in the THz region where hyperbolic phonon-polaritons can be excited.\nHere, we use this material to illustrate how the behavior of bulk and surface\nhyperbolic polaritons can be drastically modified by changing the orientation\nof the crystal's anisotropy axis with respect to its surface. We demonstrate,\nboth theoretically and experimentally, phenomena associated with the\norientation of hyperbolic media. We show the consequences of slight changes in\nthe crystal's orientation in various ways, from the creation of hyperbolic\nsurface phonon-polaritons to the demonstration of oriented asymmetric\ntransmission of radiation passing through a hyperbolic medium."
    },
    {
        "anchor": "Generalizing Fowler-Nordheim Tunneling Theory for an Arbitrary Power Law\n  Barrier: Herein, the canonical Fowler-Nordheim theory is extended by computing the\nzero-temperature transmission probability for the more general case of a\nbarrier described by a fractional power law. An exact analytical formula is\nderived, written in terms of Gauss hypergeometric functions, that fully capture\nthe transmission probability for this generalized problem, including screened\ninteraction with the image potential. First, the quality of approximation\nagainst the so far most advanced formulation of Fowler-Nordheim, where the\ntransmission is given in terms of elliptic integrals, is benchmarked. In the\nfollowing, as the barrier is given by a power law, in detail, the dependence of\nthe transmission probability on the exponent of the power law is analyzed. The\nformalism is compared with results of numerical calculations and its possible\nexperimental relevance is discussed. Finally, it is discussed how the presented\nsolution can be linked in some specific cases with an exact quantum-mechanical\nsolution of the quantum well problem.",
        "positive": "Micromagnetic simulations of absoption spectra in magnetic nanodots,\n  r.f. field perpendicular to the samples' plane: Recently developed eigenvalue method is being used to calculate absorption\nspectra in magnetic square nanodots and nanodisks. Obtained results are being\ncompared with both theoretical and experimental results obtained previously for\nsuch structures."
    },
    {
        "anchor": "Orbital magnetization in periodic insulators: Working in the Wannier representation, we derive an expression for the\norbital magnetization of a periodic insulator. The magnetization is shown to be\ncomprised of two contributions, an obvious one associated with the internal\ncirculation of bulk-like Wannier functions in the interior, and an unexpected\none arising from net currents carried by Wannier functions near the surface.\nEach contribution can be expressed as a bulk property in terms of Bloch\nfunctions in a gauge-invariant way. Our expression is verified by comparing\nnumerical tight-binding calculations for finite and periodic samples.",
        "positive": "Consistent optical and electrical determination of carrier\n  concentrations for the accurate modeling of the transport properties of\n  n-type Ge: A consistent methodology is presented to extract carrier concentrations in\nn-type Ge from measurements of the infrared dielectric function and the Hall\neffect. In the case of the optical measurements, usually carried out using\nspectroscopic ellipsometry, the carrier concentration is affected by the doping\ndependence of the conductivity effective mass, which is computed using a model\nof the electronic density of states that accounts for non-parabolicity and is\nfit to electronic structure calculations. Carrier concentrations obtained from\nHall measurements require a knowledge of the Hall factor, which is arbitrarily\nset equal to unit in most practical applications. We have calculated the Hall\nfactor for n-Ge using a model that accounts for scattering with phonons and\nwith ionized impurities. We show that determinations of the carrier\nconcentration n using our computed effective mass and Hall factor virtually\neliminates any systematic discrepancy between the two types of measurement. We\nthen use these results to compute majority carrier mobilities from measured\nresistivity values, to compare with measurements of minority carrier\nmobilities, and to fit empirical expressions to the doping dependence of the\nmobilities that can be used to model Ge devices."
    },
    {
        "anchor": "Excitons in Bulk and Layered Chromium Tri-Halides: From Frenkel to the\n  Wannier-Mott Limit: Excitons with large binding energies $\\sim$2-3 eV in CrX$_{3}$ are\nhistorically characterized as being localized (Frenkel) excitons that emerge\nfrom the atomic $d{-}d$ transitions between the Cr-3$d$-$t_{2g}$ and $e_{g}$\norbitals. The argument has gathered strength in recent years as the excitons in\nrecently made monolayers are found at almost the same energies as the bulk. The\nLaporte rule, which restricts such parity forbidden atomic transitions, can\nrelax if, at least, one element is present: spin-orbit coupling, odd-parity\nphonons or Jahn-Teller distortion. While what can be classified as a purely\nFrenkel exciton is a matter of definition, we show using an advanced first\nprinciples parameter-free approach that these excitons in CrX$_{3}$, in both\nits bulk and monolayer variants, have band-origin and do not require the\nrelaxation of Laporte rule as a fundamental principle. We show that, the\ncharacter of these excitons is mostly determined by the Cr-$d$ orbital\nmanifold, nevertheless, they appear only as a consequence of X-p states\nhybridizing with the Cr-$d$. The hybridization enhances as the halogen atom\nbecomes heavier, bringing the X-$p$ states closer to the Cr-$d$ states in the\nsequence Cl{\\textrightarrow}Br{\\textrightarrow}I, with an attendant increase in\nexciton intensity and decrease in binding energy. By applying a range of\ndifferent kinds of perturbations, we show that, moderate changes to the\ntwo-particle Hamiltonian that essentially modifies the Cr-$d$-X-$p$\nhybridization, can alter both the intensities and positions of the exciton\npeaks. A detailed analysis of several deep lying excitons, with and without\nstrain, reveals that the exciton is most Frenkel like in CrCl$_{3}$ and\nacquires mixed Frenkel-Wannier character in CrI$_{3}$.",
        "positive": "Large-scale correlated study of excited state absorptions in naphthalene\n  and anthracene: In this paper, we report theoretical calculations of the photo-induced\nabsorption (PA) spectrum of naphthalene and anthracene, with the aim of\nunderstanding those excited states, which are invisible in the linear optical\nabsorption. The excited state absorption spectra are computed from the\n$1B_{2u}^{+}$ and the $1B_{3u}^{+}$ states, and a detailed analysis of the\nmany-body character of the states contributing to various peaks in the spectra\nis presented. The calculations are performed using the Pariser-Parr-Pople (PPP)\nHamiltonian, along with the full configuration interaction (FCI) technique. The\nrole of Coulomb parameters used in the PPP Hamiltonian is examined by\nconsidering standard Ohno parameters, as well as a screened set of parameters.\nThe results of our calculations are extensively compared with the experimental\ndata where available, and very good agreement has been obtained. Moreover, our\ncalculations predict the presence of high intensity features which, to the best\nof our knowledge have not been explored earlier. We also present concrete\npredictions on the polarization properties of the PA spectrum, which can be\nverified in experiments performed on oriented samples."
    },
    {
        "anchor": "First-principles Green's-function method for surface calculations: a\n  pseudopotential localized basis set approach: We present an efficient implementation of a surface Green's-function method\nfor atomistic modeling of surfaces within the framework of density functional\ntheory using a pseudopotential localized basis set approach. In this method,\nthe system is described as a truly semi-infinite solid with a surface region\ncoupled to an electron reservoir, thereby overcoming several fundamental\ndrawbacks of the traditional slab approach. The versatility of the method is\ndemonstrated with several applications to surface physics and chemistry\nproblems that are inherently difficult to address properly with the slab\nmethod, including metal work function calculations, band alignment in thin-film\nsemiconductor heterostructures, surface states in metals and topological\ninsulators, and surfaces in external electrical fields. Results obtained with\nthe surface Green's-function method are compared to experimental measurements\nand slab calculations to demonstrate the accuracy of the approach.",
        "positive": "Asymptotic and intermediate long-time behavior of nuclear free induction\n  decays in polycrystalline solids and powders: Free induction decay (FID) measured by nuclear magnetic resonance (NMR) in a\npolycrystalline solid is the isotropic average of the FIDs for individual\nsingle crystallites. It has been recently proposed theoretically and verified\nexperimentally that the long-time behavior of single-crystal FIDs has the\nuniversal form of exponentially decaying sinusoidal oscillations.\nPolycrystalline averaging complicates the situation theoretically, while the\navailable experimental evidence is also ambiguous. Exponentially decaying\nsinusoidal oscillations have been observed for Xe-129 in polycrystalline solid\nxenon but not for F-19 in the powder of CaF2. In this paper, we present the\nfirst principles FID calculations for the powders of both CaF2 and solid xenon.\nIn both cases, the asymptotic long-time behavior has the expected form of\nexponentially decaying sinusoidal oscillations, which is determined by the\nsingle crystallite FID with the slowest exponential decay. However, this\nbehavior appears only at rather small values of the signal that have not yet\nbeen measured in experiments. At intermediate times accessible experimentally,\na polycrystalline FID depends on the distribution of the exponential decay\nconstants and oscillation frequencies for single crystallite FIDs. In CaF2,\nthese parameters are relatively broadly distributed, and as a result, the\nsinusoidal long-time oscillations become somewhat washed out. In contrast, the\nsingle crystallite parameters are more clustered in solid xenon, and, as a\nresult, the experimentally observable range is characterized by well-defined\noscillation frequency and exponential decay constant even though both of these\nparameters do not represent the true long-time behavior. The above difference\nof the intermediate FID behavior originates from the difference of the crystal\nstructures of solid xenon and CaF2."
    },
    {
        "anchor": "Giant optical enhancement of strain gradient in ferroelectric thin films\n  and its physics origin: The coupling between strain gradients and polarization, known as\nflexoelectricity, offers a new mechanism to control the functionality of\ndielectric materials. However, for the effect to be practically attractive,\ndynamic control of the strain gradient with magnitudes far exceeding those\nachievable via mechanical deformation (~10 $m^{-1}$) is needed.\nStrain-engineered thin films exhibit extraordinary strain gradients of\n$10^5-10^6 m{-1}$ arising from structural relaxation within a short space range\nthat greatly enhances the steady-state flexoelectric effect. Here we report a\ngiant, optically initiated dynamic enhancement of the strain gradient, also on\nthe order of $10^5 -10^6 m^{-1}$, in ferroelectric BiFeO3 epitaxial thin films\nvia time-dependent coherence analysis of X-ray diffractions. The finding opens\nthe door for dynamic coupling of the flexoelectric effect with light, making\noptical switching of polarization, and thus application such as direct optical\nwriting of non-volatile ferroelectric memory, possible. A combination of\ntime-resolved X-ray scattering and optical spectroscopy shows that the\nenhancement of the strain gradient is due to a piezoelectric effect driven by a\ntransient screening electric field, opening the opportunity for new ways of\nstudying flexoelectric effect in strain engineered ferroelectric thin films.",
        "positive": "Hydrogenated-Graphene encapsulated Graphene: A versatile material for\n  device applications: Graphene and its heterostructures exhibit interesting electronic properties\nand are explored for quantum spin Hall effect(QSHE) and magnetism based device\napplications. In present work, we propose a heterostructure of graphene\nencapsulated by hydrogenated graphene which could be a promising candidate for\na variety of device applications. We have carried out DFT calculations on this\nsystem to check its feasibility to be a versatile material. We found that\nelectronic states of multilayer pristine graphene, especially Dirac cone, an\nimportant feature to host QSHE, can be preserved by sandwiching it by fully\nhydrogenated graphene. Interference of electronic states of hydrogenated\ngraphene was insignificant with those of graphene. States of graphene were also\nfound to be stable upon application of electric field up to 2.5V/nm. For device\napplications, multilayer graphene or its heterostructures are required to be\ndeposited on a substrate, which interacts with system opening up a gap at Dirac\ncone making it less suitable for QSHE applications and hydrogenated graphene\ncan prevent it. Magnetization in these hydrogenated graphene sandwiched\ngraphene may be induced by creating vacancies or distortions in hydrogenated\ngraphene, which was found to have minimal effect on graphenes electronic\nstates, thus providing an additional degree of manipulation. We also performed\na set of calculations to explore its applicability for detecting some\nmolecules. Our results on trilayer graphene encapsulated by hydrogenated\ngraphene indicate that all these observations can be generalized to systems\nwith a larger number of graphene layers, indicating that multilayer graphene\nsandwiched between two hydrogenated graphene is a versatile material that can\nbe used in QSHE, sensor devices, etc."
    },
    {
        "anchor": "Synthesis of Dispersed Metal Particles for Applications in\n  Photovoltaics, Catalysis, and Electronics: In colloid and nanoparticle chemistry, particle size, shape, crystallinity,\nsurface morphology and composition are controlled by employing the mechanisms\nof burst nucleation, diffusional growth, aggregation, or their combinations.\nHere we review and survey practical examples of recently developed methods for\npreparing metal colloids and nanoparticles for industrial applications such as\nphotovoltaics, catalysis, and consumer electronics. We discuss relevant\ntheoretical models, many of which are general, and identify growth mechanisms\nthat play a major role in other systems and applications as well.",
        "positive": "Superior effect of edge relative to basal plane functionalization of\n  graphene in enhancing polymer-graphene nanocomposite thermal conductivity-A\n  combined molecular dynamics and Greens functions study: To achieve high thermal conductivity (k) of polymer graphene nanocomposites,\nit is critically important to achieve efficient thermal coupling between\ngraphene and its surrounding polymers through effective functionalization\nschemes. In this work, we demonstrate that edge-functionalization of graphene\nnanoplatelets (GnPs) can enable a larger enhancement of effective thermal\nconductivity in polymer-graphene nanocomposites, relative to basal plane\nfunctionalization. Effective thermal conductivity for edge case is predicted,\nthrough molecular dynamics simulations, to be up to 48% higher relative to\nbasal plane bonding for 35 wt.% graphene loading with 10 layers thick\nnanoplatelets. This unique result opens up promising new avenues for achieving\nhigh thermal-conductivity polymer materials, which is of key importance for a\nwide range of thermal management technologies. The anisotropy of thermal\ntransport in single layer graphene leads to very high in-plane thermal\nconductivity (~2000 W/mK) compared to the low out-of-plane thermal conductivity\n(~10 W/mK). Likewise, in multilayer graphene nanoplatelet (GnP), the thermal\nconductivity across the layers is even lower due to the weak van der Waals\nbonding between each pair of layers. Edge functionalization couples the polymer\nchains to the high in-plane thermal conduction pathway of graphene, thus\nleading to high overall high composite thermal conductivity. Basal-plane\nfunctionalization, however, lowers the thermal resistance between the polymer\nand the surface graphene sheets of the nanoplatelet only, causing the heat\nconduction through inner layers to be less efficient, thus resulting in basal\nplane scheme to be outperformed by edge scheme. The present study fundamentally\nenables novel pathways for achieving high thermal-conductivity polymer\ncomposites."
    },
    {
        "anchor": "Step bunching of vicinal 6H-SiC{0001} surfaces: We use kinetic Monte Carlo simulations to understand growth- and\netching-induced step bunching of 6H-SiC{0001} vicinal surfaces oriented towards\n[1-100] and [11-20]. By taking account of the different rates of surface\ndiffusion on three inequivalent terraces, we reproduce the experimentally\nobserved tendency for single bilayer height steps to bunch into half unit cell\nheight steps. By taking account of the different mobilities of steps with\ndifferent structures, we reproduce the experimentally observed tendency for\nadjacent pairs of half unit cell height steps to bunch into full unit cell\nheight steps. A prediction of our simulations is that growth-induced and\netching-induced step bunching lead to different surface terminations for the\nexposed terraces when full unit cell height steps are present.",
        "positive": "Roughness evolution induced by third-body wear: Surface roughness is a key factor when it comes to friction and wear, as well\nas to other physical properties. These phenomena are controlled by mechanisms\nacting at small scales, in which the topography of apparently-flat surfaces is\nrevealed. Roughness in natural surfaces has been reported to conform to\nself-affine statistics in a wide variety of settings (ranging from earthquake\nphysics to micro-electro-mechanical devices), meaning that the height profile\ncan be described using a spectrum where the amplitude is proportional to its\nwavelength raised to a constant power, which is related to a statistical\nparameter named Hurst exponent. We analyze the roughness evolution in atomistic\nsurfaces during molecular dynamics simulations of wear. Both pairs of\ninitially-flat and initially-rough surfaces in contact are worn by a third body\nformed by particles trapped between them during relative sliding. During the\nfirst sliding stages, the particles trapped between the first bodies scratch\nthe surfaces. Once the former become coated with atoms from the latter, the\nwear process slows down and becomes \"adhesive-like\". The initial particle sizes\nare consistent with the minimum size to be expected for the debris, but tend to\ngrow by material removal from the surfaces and to agglomerate. We show that,\nfor the particular configurations under consideration, the surface roughness\nseems to converge to a steady state characterized by Hurst exponent close to\n0.8, independently of the initial conditions."
    },
    {
        "anchor": "Dirac semimetal and topological phase transitions in A3Bi (A=Na, K, Rb): The three-dimensional (3D) Dirac point, where two Weyl points overlap in\nmomentum space, is usually unstable and hard to realize. Here we show, based on\nthe first-principles calculations and effective model analysis, that\ncrystalline $A_3$Bi ($A$=Na, K, Rb) are Dirac semimetals with bulk 3D Dirac\npoints protected by crystal symmetry. They possess non-trivial Fermi arcs on\nthe surfaces, and can be driven into various topologically distinct phases by\nexplicit breaking of symmetries. Giant diamagnetism, linear quantum\nmagnetoresistance, and quantum spin-Hall effect will be expected for such\ncompounds.",
        "positive": "Lattice dynamics and Raman spectrum of supertetragonal PbVO3: Lead vanadate PbVO3 is a polar crystal with a P4mm space group at ambient\nconditions. It is isostructural with the model soft-mode driven ferroelectric\nPbTiO3, but differs from it by the so-called 'supertetragonal' elongation of\nits unit cell. In this paper, we report a combined study of the lattice\ndynamics of PbVO3 by Raman spectroscopy at room temperature and first-principle\ncalculations. All zone-center transverse optical (TO) phonon modes are\nidentified by polarized, angle-dependent Raman spectroscopy and assigned as\nfollows: E modes at 136, 269, 374 and 508 cm-1, A1 modes at 188, 429 and 874\ncm-1 and B1 mode at 319 cm-1. The calculations confirm the experimental\nsymmetry assignment and allow to obtain the longitudinal (LO) phonons\nwavenumbers. Besides, we analyze the mode eigenvectors in detail, in order to\nidentify the atomic displacements associated with each mode and compare them\nwith PbTiO3. In spite of their differences in chemistry and strain, the phonon\neigenvectors are found to be remarkably comparable in both compounds. We\ndiscuss the position of the ferroelectric soft mode in PbVO3 as compared to\nPbTiO3. A sizeable splitting of the B1+E modes appears as a characteristic\nfeature of supertetragonal phases. The peculiarity of the vanadyl V-O bond\nfrequency in PbVO3 is also addressed."
    },
    {
        "anchor": "Anisotropic Electron-Photon-Phonon Coupling in Layered MoS2: Transition metal dichalcogenide, especially MoS2 has attracted lot of\nattention recently owing to its tunable visible range band gap and anisotropic\nelectronic and transport properties. Here, we report a comprehensive inelastic\nlight scattering measurements on CVD grown (horizontally and vertically aligned\nflakes) as well as single crystal flakes of MoS2, probing the anisotropic\noptical response via studying the polarization dependence intensity of the\nRaman active phonon modes as a function of different incident photon energy and\nflake thickness. Our polarization dependent Raman studies intriguingly revealed\nstrong anisotropic behavior reflected in the anomalous renormalization of the\nmodes intensity as a function of flake thickness, phonons and photon energy.\nOur observations reflects the strong anisotropic light-matter interaction in\nthis high crystalline symmetric layered MoS2 system especially for the in-plane\nvibrations, which is crucial for understanding as well application of these\nmaterials for future application such as optoelectronic applications.",
        "positive": "Dipolar coupling and multidomain states in perpendicularly polarized\n  nanostructures: Stripe states in multilayer systems with perpendicular polarization are\ninvestigated by analytical calculations within a general continuum approach,\napplicable to ferromagnetic, ferroelectric, or ferroelastic nanoscale\nsuperlattices. The competition between the long-range depolarization effect and\nshort-range interlayer couplings can stabilize monodomain states and unusual\nstripe phase ground states with antiparallel polarization in adjacent layers.\nGeometric parameters of stable stripe domain states and the phase transitions\nlines between single domain states, aligned and antialigned stripe states have\nbeen derived. The theory is applied to analyze multidomain states and phase\ntransitions in antiferromagnetically coupled multilayers [CoPt]/Ru."
    },
    {
        "anchor": "Collective Behaviour of Cr$^{3+}$ ions in Ruby Revealed by Whispering\n  Gallery Modes: We present evidence for collective action of Cr$^{3+}$ ion impurities in a\nhighly doped ruby crystal at microwave frequencies. The cylindrical geometry of\nthe crystal allows for the creation of a superradiant, or \"spin-mode\" doublet,\nwith spatial structure similar to that of microwave whispering gallery modes\n(WGMs). This results in a strict criteria of selection rules regarding the\ninteraction of resonant WGMs and spin-modes; namely that only modes with the\nsame wavenumber and azimuthal phase may interact. What results is an avoided\nlevel crossing between the two, in which both WGM doublet constituents are seen\nto interact with the spin resonance. We demonstrate that a four harmonic\noscillator model is necessary to accurately describe this result.",
        "positive": "Predicting polarization enhancement in multicomponent ferroelectric\n  superlattices: Ab initio calculations are utilized as an input to develop a simple model of\npolarization in epitaxial short-period CaTiO3/SrTiO3/BaTiO3 superlattices grown\non a SrTiO3 substrate. The model is then combined with a genetic algorithm\ntechnique to optimize the arrangement of individual CaTiO3, SrTiO3 and BaTiO3\nlayers in a superlattice, predicting structures with the highest possible\npolarization and a low in-plane lattice constant mismatch with the substrate.\nThis modelling procedure can be applied to a wide range of layered\nperovskite-oxide nanostructures providing guidance for experimental development\nof nanoelectromechanical devices with substantially improved polar properties."
    },
    {
        "anchor": "The crystalline structure of orthorhombic SrRuO$_3$: Application of\n  hybrid scheme to the density functionals revised for solids: The crystalline structure of ground-state orthorhombic SrRuO$_3$ is\nreproduced by applying hybrid density functional theory scheme to the\nfunctionals based on the revised generalized-gradient approximations for\nsolid-state calculations. The amount of Hartree-Fock (HF) exchange energy is\nvaried in the range of $5-20\\%$ in order to systematically ascertain the\noptimum value of HF mixing which in turn ensures the best correspondence to the\nexperimental measurements. Such investigation allows to expand the set of tools\nthat could be used for the efficient theoretical modelling of, for example,\nonly recently stabilized phases of SrRuO$_3$.",
        "positive": "Stochastic Simulation of Nonequilibrium Heat Conduction in Extended\n  Molecule Junctions: Understanding phononic heat transport processes in molecular junctions is a\ncentral issue in the developing field of nanoscale heat conduction and\nmanipulation. Here we present a Stochastic Nonequlibrium Molecular Dynamics\nsimulation framework to investigate heat transport processes in molecular\njunctions in and beyond the linear response regime. We use extended molecular\nmodels which filter Markovian heat reservoirs through an intermediate substrate\nregion, to provide a realistic and controllable effective bath spectral\ndensity. The results obtained for alkanedithol molecules connecting gold\nsubstrates agree with previous nonequilibrium Green's function calculations in\nfrequency domain, and match recent experimental measurements (e.g. thermal\nconductance around 20 pW/K for alkanedithiols in single molecular junctions)\nClassical MD simulations using the full molecular forcefield and quantum\nLandauer-type calculations based on the harmonic part of the same forcefield\nare compared, and the similarity of the results indicate that heat transport is\ndominated by modes in the lower frequency range. Heat conductance simulations\non polyynes of different lengths illuminates the effects of molecular\nconjugation on thermal transport."
    },
    {
        "anchor": "Dependence of atomic arrangement on length of flat bands in zigzag BC2N\n  nanoribbons: We theoretically study the electronic properties of BC2N nanoribbons with\nzigzag edges using a tight binding model. We show that the zigzag BC2N\nnanoribbons have the flat bands and edge states when atoms are arranged as\nB-C-N-C along the zigzag lines. The length of the flat bands in the wavevector\nspace depends on the atomic arrangement. This property can be explained by the\ndeviation of the linear dispersion of the BC2N sheet from K point of the\nhoneycomb lattice. The charge distributions in the edge states depend on the\natomic arrangement. We also show that the charge distribution of the edge\nstates in zigzag BC2N nanoribbons where the outermost sites are occupied with B\nand N atoms is different from those in conventional graphene zigzag edge. Such\ncharge distribution causes different magnetic structures. We investigate the\nmagnetic structure of BC2N nanoribbons with zigzag edges using the Hubbard\nmodel within a mean field approximation. At the zigzag edge where the outermost\nsites are occupied with B and N atoms, ferromagnetic structure appears when the\nsite energies are larger than the on-site Coulomb interaction.",
        "positive": "Band Structure and Polarization Effects in Photothermoelectric\n  Spectroscopy of a Bi2Se3 Device: Bi2Se3 is a prototypical topological insulator which has a small band gap\n(~0.3 eV) and topologically protected conducting surface states. This material\nexhibits quite strong thermoelectric effects. Here we show in a mechanically\nexfoliated thick (~100 nm) nanoflake device that we can measure the energy\ndependent optical absorption through the photothermoelectric effect. Spectral\nsignatures are seen for a number of optical transitions between the valence and\nconduction bands, including a broad peak at 1.5 eV which is likely dominated by\nbulk band-to-band optical transitions but is at the same energy as the well\nknown optical transition between the two topologically protected conducting\nsurface states. We also observe a surprising linear polarization dependence in\nthe response of the device that reflects the influence of the metal contacts."
    },
    {
        "anchor": "Synthesis and characterization of chloride doped polyaniline by bulk\n  oxidative chemical polymerization.Doping effect on electrical conductivity: Conductive polymers or \"organic metals\" are highly engineered nanostructured\nmaterials made from organic building blocks. They are candidates as molecular\nwires for nanotechnology applications in molecular electronics. The conduction\nin these polymers is due to the presence of delocalized molecular orbitals. In\nthis work, we present the synthesis of chloride doped polyaniline by bulk\noxidative chemical polymerization using a solid aniline salt as a monomer\ninstead of liquid aniline to diminish toxic hazards. The FTIR and UV-visible\nspectra confirmed the expected structure of the polymer. The electrical\nconductivity measured using a four-probe method was 1.7 S/cm. The dependence of\nimpedance modulus on frequency was measured using an HP impedance analyzer in\nthe range 10 kHz-13 MHz. The influence of doping and the preparation\ntemperature on the electrical conductivity were also investigated.",
        "positive": "Direct observation of spin-polarised bulk bands in an\n  inversion-symmetric semiconductor: Methods to generate spin-polarised electronic states in non-magnetic solids\nare strongly desired to enable all-electrical manipulation of electron spins\nfor new quantum devices. This is generally accepted to require breaking global\nstructural inversion symmetry. In contrast, here we present direct evidence\nfrom spin- and angle-resolved photoemission spectroscopy for a strong spin\npolarisation of bulk states in the centrosymmetric transition-metal\ndichalcogenide WSe$_2$. We show how this arises due to a lack of inversion\nsymmetry in constituent structural units of the bulk crystal where the\nelectronic states are localised, leading to enormous spin splittings up to\n$\\sim\\!0.5$ eV, with a spin texture that is strongly modulated in both real and\nmomentum space. As well as providing the first experimental evidence for a\nrecently-predicted `hidden' spin polarisation in inversion-symmetric materials,\nour study sheds new light on a putative spin-valley coupling in\ntransition-metal dichalcogenides, of key importance for using these compounds\nin proposed valleytronic devices."
    },
    {
        "anchor": "Foundations of stochastic time-dependent current-density functional\n  theory for open quantum systems: Potential pitfalls and rigorous results: We clarify some misunderstandings on the time-dependent current density\nfunctional theory for open quantum systems we have recently introduced [M. Di\nVentra and R. D'Agosta, Phys. Rev. Lett. {\\bf 98}, 226403 (2007)]. We also show\nthat some of the recent formulations attempting to improve on this theory\nsuffer from some inconsistencies, especially in establishing the mapping\nbetween the external potential and the quantities of interest. We offer a\ngeneral argument about this mapping, showing that it must fulfill certain\n\"dimensionality\" requirements.",
        "positive": "A coarse-grained phase-field crystal model of plastic motion: The phase-field crystal model in its amplitude equation approximation is\nshown to provide an accurate description of the deformation field in defected\ncrystalline structures, as well as of dislocation motion. We analyze in detail\nthe elastic distortion and stress regularization at a dislocation core and show\nhow the Burgers vector density can be directly computed from the topological\nsingularities of the phase-field amplitudes. Distortions arising from these\namplitudes are then supplemented with non-singular displacements to enforce\nmechanical equilibrium. This allows for the consistent separation of plastic\nand elastic time scales in this framework. A finite element method is\nintroduced to solve the combined amplitude and elasticity equations, which is\napplied to a few prototypical configurations in two spatial dimensions for a\ncrystal of triangular lattice symmetry: i) the stress field induced by an edge\ndislocation with an analysis of how the amplitude equation regularizes stresses\nnear the dislocation core, ii) the motion of a dislocation dipole as a result\nof its internal interaction, and iii) the shrinkage of a rotated grain. We also\ncompare our results with those given by other extensions of classical\nelasticity theory, such as strain-gradient elasticity and methods based on the\nsmoothing of Burgers vector densities near defect cores."
    },
    {
        "anchor": "Self-Organization of a 2D Lattice on a Surface of Ge Single Crystal\n  after Irradiation with Yag: ND Laser: Experimentally observed self-organization of a 2D lattice on the surface of\nGe single crystal after irradiation by pulsed YAG: Nd laser is repoted. The\ncalculation of time depended distribution of temperature in bulk of the Ge\nsample show that overheating of the crystal lattice occurs at laser radiation\nintensities exceeding 30MW/cm2.The two temperature gradients are exists.",
        "positive": "Surface influence on stability and structure of III-V nanorods:\n  First-principles studies: We report ab initio investigations of hexagon-shaped, [111]/[0001] oriented\nIII-V semiconductor nanowires with varying crystal structure, surface\npassivation, surface orientation, and diameter. Their stability is dominated by\nthe free surface energies of the corresponding facets which differ only weakly\nfrom those of free surfaces. We observe a phase transition between local\nzinc-blende and wurtzite geometry versus preparation conditions of the\nsurfaces, which is accompanied by a change in the facet orientation. The\ninfluence of the actual III-V compound remains small. The atomic relaxation of\nnanowires gives rise to smaller bond lengths in comparison to the bulk\nzinc-blende structures resulting also in somewhat reduced bilayer thicknesses\nparallel to the growth direction."
    },
    {
        "anchor": "Nonharmonic Phonons in $\u03b1$-Iron at High Temperatures: Phonon densities of states (DOS) of bcc $\\alpha$-$^{57}$Fe were measured from\nroom temperature through the 1044K Curie transition and the 1185K fcc\n$\\gamma$-Fe phase transition using nuclear resonant inelastic x-ray scattering.\nAt higher temperatures all phonons shift to lower energies (soften) with\nthermal expansion, but the low transverse modes soften especially rapidly above\n700K, showing strongly nonharmonic behavior that persists through the magnetic\ntransition. Interatomic force constants for the bcc phase were obtained by\niteratively fitting a Born-von K\\'{a}rm\\'{a}n model to the experimental phonon\nspectra using a genetic algorithm optimization. The second-nearest-neighbor\nfitted axial force constants weakened significantly at elevated temperatures.\nAn unusually large nonharmonic behavior is reported, which increases the\nvibrational entropy and accounts for a contribution of 35 meV/atom in the free\nenergy at high temperatures. The nonharmonic contribution to the vibrational\nentropy follows the thermal trend of the magnetic entropy, and may be coupled\nto magnetic excitations. A small change in vibrational entropy across the\n$\\alpha$-$\\gamma$ structural phase transformation is also reported.",
        "positive": "Ab initio Ultrafast Spin Dynamics in Solids: Spin relaxation and decoherence is at the heart of spintronics and spin-based\nquantum information science. Currently, theoretical approaches that can\naccurately predict spin relaxation of general solids including necessary\nscattering pathways and capable for ns to ms simulation time are urgently\nneeded. We present a first-principles real-time density-matrix approach based\non Lindblad dynamics to simulate ultrafast spin dynamics for general\nsolid-state systems. Through the complete first-principles descriptions of\npump, probe and scattering processes including electron-phonon,\nelectron-impurity and electron-electron scatterings with self-consistent\nelectronic spin-orbit couplings, our method can directly simulate the ultrafast\npump-probe measurements for coupled spin and electron dynamics over ns at any\ntemperatures and doping levels. We first apply this method to a prototypical\nsystem GaAs and obtain excellent agreement with experiments. We find that the\nrelative contributions of different scattering mechanisms and phonon modes\ndiffer considerably between spin and carrier relaxation processes. In sharp\ncontrast to previous work based on model Hamiltonians, we point out that the\nelectron-electron scattering is negligible at room temperature but becomes\ndominant at low temperatures for spin relaxation in n-type GaAs. We further\nexamine ultrafast dynamics in novel spin-valleytronic materials - monolayer and\nbilayer WSe2 with realistic defects. We find that spin relaxation is highly\nsensitive to local symmetry and chemical bonds around defects. Our work\nprovides a predictive computational platform for spin dynamics in solids, which\nhas unprecedented potentials for designing new materials ideal for spintronics\nand quantum information technology."
    },
    {
        "anchor": "Polaronic Contributions to Friction in a Manganite Thin Film: Despite the huge importance of friction in regulating movement in all natural\nand technological processes, the mechanisms underlying dissipation at a sliding\ncontact are still a matter of debate. Attempts to explain the dependence of\nmeasured frictional losses at nanoscale contacts on the electronic degrees of\nfreedom of the surrounding materials have so far been controversial. Here, it\nis proposed that friction can be explained by considering damping of stick-slip\npulses in a sliding contact. Based on friction force microscopy studies of\nLa$_{(1-x)}$Sr$_x$MnO$_3$ films at the ferromagnetic-metallic to\nparamagnetic-polaronic conductor phase transition, it is confirmed that the\nsliding contact generates thermally-activated slip pulses in the nanoscale\ncontact, and argued that these are damped by direct coupling into phonon bath.\nElectron-phonon coupling leads to the formation of Jahn-Teller polarons and a\nclear increase in friction in the high temperature phase. There is no evidence\nfor direct electronic drag on the atomic force microscope tip nor any\nindication of contributions from electrostatic forces. This intuitive scenario,\nthat friction is governed by the damping of surface vibrational excitations,\nprovides a basis for reconciling controversies in literature studies as well as\nsuggesting possible tactics for controlling friction.",
        "positive": "Direct observation of optically induced transient structures in graphite\n  using ultrafast electron crystallography: We use ultrafast electron crystallography to study structural changes induced\nin graphite by a femtosecond laser pulse. At moderate fluences of ~< 21mJ/cm^2,\nlattice vibrations are observed to thermalize on a time scale of ~8ps. At\nhigher fluences approaching the damage threshold, lattice vibration amplitudes\nsaturate. Following a marked initial contraction, graphite is driven\nnonthermally into a transient state with sp^3-like character, forming\ninterlayer bonds. Using ab initio density functional calculations, we trace the\ngoverning mechanism back to electronic structure changes following the\nphoto-excitation."
    },
    {
        "anchor": "Dark exciton optical spectroscopy of a semiconducting quantum dot\n  embedded in a nanowire: Photoluminescence of a single CdSe quantum dot embedded in a ZnSe nanowire\nhas been investigated. It has been found that the dark exciton has a strong\ninfluence on the optical properties. The most visible influence is the strongly\nreduced excitonic emission compared to the biexcitonic one. Temperature\ndependent lifetime measurements have allowed us to measure a large splitting of\n$\\Delta E = 6 $ meV between the dark and the bright exciton as well as the spin\nflip rates between these two states.",
        "positive": "Effective Hamiltonian Methods for Predicting the Electrocaloric Behavior\n  of BaTiO3: The perovskite crystal BaTiO3 is modeled using a first-principles based\neffective Hamiltonian and molecular dynamics simulations are performed to\nestimate the pyroelectric response. The electrocaloric temperature change,\n\\DeltaT, is calculated for different temperatures and externally applied\nelectric fields. It is found that it is possible to achieve a large \\DeltaT,\naround 5-6 K, for a relatively small electric field gradient, less than 100\nkV/cm, if the applied fields have a small absolute magnitude."
    },
    {
        "anchor": "Controlled Transformation of Electrical, Magnetic and Optical Material\n  Properties by Ion Beams: Key circumstance of radical progress for technology of XXI century is the\ndevelopment of a technique which provides controllable producing\nthree-dimensional patterns incorporating regions of nanometer sizes and\nrequired physical and chemical properties. Our paper for the first time\nproposes the method of purposeful direct transformation of the most important\nsubstance physical properties, such as electrical, magnetic, optical and others\nby controllable modification of solid state atomic constitution.\n  The basis of the new technology is discovered by us effect of selective atom\nremoving out of thin di- and polyatomic films by beams of accelerated\nparticles. Potentials of that technique have been investigated and confirmed by\nour numerous experiments. It has been shown, particularly, that selective atom\nremoving allows to transform in a controllable way insulators into metals,\nnon-magnetics into magnetics, to change radically optical features and some\nother properties of materials.\n  The opportunity to remove selectively atoms of a certain sort out of solid\nstate compounds is, as such, of great interest in creating technology\nassociated primarily with needs of nanoelectronics as well as many other\n\"nano-problems\" of XXI century.",
        "positive": "Mid-infrared optical properties of pyrolytic boron nitride in the 390 to\n  1050 $^{\\circ}$C temperature range using spectral emissivity measurements: This paper shows a systematic experimental and theoretical study on the\ntemperature dependence of the infrared optical properties of pyrolytic boron\nnitride (pBN), from 390 to 1050 $^{\\circ}$CC for wavelengths between 4 and 16\n{\\mu}m. The temperature dependence of these properties has never been analyzed\nbefore. The measured emissivity spectra were fitted to a dielectric function\nmodel and an effective medium approximation. The phonon frequencies and\ndielectric constants agreed well with room temperature experimental values from\nthe literature, as well as with ab initio and first principles calculations. In\naddition, the phonon frequencies of the perpendicular mode and the dielectric\nconstants of the parallel mode showed an appreciable parabolic temperature\ndependence, which justifies the interest of more theoretical efforts in order\nto explain this behavior. Finally, the results of this work demonstrate that\nthermal emission spectroscopy allows obtaining the values of the optical and\ndielectric parameters of impure ceramic materials in a simple manner as a\nfunction of temperature."
    },
    {
        "anchor": "Large spin Hall angle and spin mixing conductance in highly resistive\n  antiferromagnetic Mn2Au: Antiferromagnetic (AFM) materials recently have shown interest in the\nresearch in spintronics due to its zero stray magnetic field, high anisotropy,\nand spin orbit coupling. In this context, the bi-metallic AFM Mn2Au has drawn\nattention because it exhibits unique properties and its Neel temperature is\nvery high. Here, we report spin pumping and inverse spin Hall effect\ninvestigations in Mn2Au and CoFeB bilayer system using ferromagnetic resonance.\nWe found large spin Hall angle {\\theta}_SH = 0.22",
        "positive": "Lattice swelling and modulus change in a helium-implanted tungsten\n  alloy: X-ray micro-diffraction, surface acoustic wave measurements, and\n  multiscale modelling: Using X-ray micro-diffraction and surface acoustic wave spectroscopy, we\nmeasure lattice swelling and elastic modulus changes in a W-1%Re alloy after\nimplantation with 3110 appm of helium. A fraction of a percent observed lattice\nexpansion gives rise to an order of magnitude larger reduction in the surface\nacoustic wave velocity. A multiscale elasticity, molecular dynamics, and\ndensity functional theory model is applied to the interpretation of\nobservations. The measured lattice swelling is consistent with the relaxation\nvolume of self-interstitial and helium-filled vacancy defects that dominate the\nhelium-implanted material microstructure. Molecular dynamics simulations\nconfirm the elasticity model for swelling. Elastic properties of the implanted\nsurface layer also change due to defects. The reduction of surface acoustic\nwave velocity predicted by density functional theory calculations agrees\nremarkably well with experimental observations."
    },
    {
        "anchor": "Surface melting of nanoscopic epitaxial films: By introducing finite size surface and interfacial excess quantities,\ninteractions between interfaces are shown to modify the usual surface\npremelting phenomenon. It is the case of surface melting of a thin solid film s\ndeposited on a planar solid substrate S. More precisely to the usual wetting\ncondition of the solid s by its own melt l, necessary for premelting (wetting\nfactor F<0), is adjoined a new quantity G describing the interactions of the\nl/s interface with the s/S interface. When G>0 this interface attraction boosts\nthe premelting so that a two stage boosted surface premelting is foreseen: a\ncontinuous premelting, up to roughly half the deposited film, is followed by an\nabrupt first order premelting. When G<0 these interfaces repell each other so\nthat premelting is refrained and the film remains partly solid above the bulk\nmelting point (overheating) what is called astride melting. Elastic stress\nmodifies both types of melting curves. Bulk and surface stresses have to be\ndistinguished.",
        "positive": "Spin decoherence in n-type GaAs: the effectiveness of the third-body\n  rejection method for electron-electron scattering: We study the spin decoherence in n-type bulk GaAs for moderate electronic\ndensities at room temperature using Ensemble Monte Carlo method. We demonstrate\nthat the third-body rejection method devised by Ridley can be successfully\nadapted to Ensemble Monte Carlo algorithm, and used to tackle the problem of\nthe electron-electron contribution to spin decoherence."
    },
    {
        "anchor": "Orientational Ordering of Nonplanar Phthalocyanines on Cu(111): Strength\n  and Orientation of the Electric Dipole Moment: In order to investigate the orientational ordering of molecular dipoles and\nthe associated electronic properties, we studied the adsorption of\nchlorogallium phthalocyanine molecules (GaClPc, Pc=C_32N_8H_16) on Cu(111)\nusing the X-ray standing wave technique, photoelectron spectroscopy, and\nquantum chemical calculations. We find that for sub-monolayer coverages on\nCu(111) the majority of GaClPc molecules adsorb in a 'Cl-down' configuration by\nforming a covalent bond to the substrate. For bilayer coverages the XSW data\nindicate a co-existence of the 'Cl-down' and 'Cl-up' configuration on the\nsubstrate. The structural details established for both cases and supplementary\ncalculations of the adsorbate system allow us to analyze the observed change of\nthe work function.",
        "positive": "Melting dislocation transition in composite lithium greases with\n  copper(II) carboxylate mesogenic additives: We propose the theoretical description for the temperature and concentration\nphase transformations in composite lithium grease doped with the mesogenic\nadditives of the copper(II) carboxylates family, copper(II) valerate and\nisovalerate, in the concentration range 1, 5, 10, 20 wt. percents. The changes\nin character of specific electric conductivity of these composites manifested\nin experiments on dielectric spectroscopy in the measuring electric field of\nthe frequencies 100 Hz - 1 MHz and polarization microscopy, are reliable caused\nby reversible phase transitions from the discotic phase to isotropic one or at\nheating from room temperature to 391 K. We study correlations between defect\nstructure and electrical properties of these composites using the model of the\nBKT transition. This transformation from the discotic to isotropic phase is\nassociated with the evolution of topological defects dislocations induced by\nthe mesogenic additives. The screw, transverse edge and longitudinal\ndislocations are realized in this case. We apply the numerical Monte Carlo\ntechnique to define their critical properties in the BKT transition."
    },
    {
        "anchor": "Comparison of dislocation density tensor fields derived from discrete\n  dislocation dynamics and crystal plasticity simulations of torsion: The importance of accurate simulation of the plastic deformation of ductile\nmetals to the design of structures and components is well-known. Many\ntechniques exist that address the length scales relevant to deformation pro-\ncesses, including dislocation dynamics (DD), which models the interaction and\nevolution of discrete dislocation line segments, and crystal plasticity (CP),\nwhich incorporates the crystalline nature and restricted motion of dis-\nlocations into a higher scale continuous field framework. While these two\nmethods are conceptually related, there have been only nominal efforts focused\non the system-level material response that use DD-generated information to\nenhance the fidelity of plasticity models. To ascertain to what degree the\npredictions of CP are consistent with those of DD, we compare their global and\nmicrostructural response in a number of deformation modes. After using\nnominally homogeneous compression and shear deformation dislocation dynamics\nsimulations to calibrate crystal plasticity flow rule parameters, we compare\nnot only the system-level stress-strain response of prismatic wires in torsion\nbut also the resulting geometrically necessary dislocation density fields. To\nestablish a connection between explicit description of dislocations and the\ncontinuum assumed with crystal plasticity simulations, we ascertain the minimum\nlength-scale at which meaningful dislocation density fields appear. Our results\nshow that, for the case of torsion, the two material models can produce\ncomparable spatial dislocation density distributions.",
        "positive": "Morphology of Thin Films of Gold Grown on CaF2 (100) and (111): Thin films of gold were deposited on single crystalline CaF2 substrates of\n(100) and (111) orientation by thermal evaporation. The resulting film\nstructure was analyzed by means of atomic force microscopy in dependence of\nsubstrate temperature and deposition thickness. A marked substrate dependency\nwas found. On CaF2 (100), extended and flat plateaus with diameters of several\nhundreds of nanometers form in a network-like arrangement for deposition\nthicknesses between 30 and 45 nm. On CaF2 (111), closed films of small average\nroughness develop at film thicknesses between 70 and 90 nm. These films do not\nexhibit, however, the extended plateaus present in the former case. On basis of\nthe rule of Brueck and Engel, epitaxial growth of Au (100) crystallites on both\nsurfaces is suggested. For both substrates, the epitaxial temperature was\ndetermined to Te = 320 C"
    },
    {
        "anchor": "The high-pressure alpha/beta phase transition in lead sulphide (PbS):\n  X-ray powder diffraction and quantum mechanical calculations: The high-pressure behaviour of PbS was investigated by angular dispersive\nX-ray powder diffraction up to pressures of 6.8 GPa. Experiments were\naccompanied by first principles calculations at the density functional theory\nlevel. By combining both methods reliable data for the elastic properties of\nrock-salt type alpha- and high-pressure beta-PbS could be obtained. beta-PbS\ncould be determined to crystallise in the CrB-type (B33), with space group\nCmcm. The reversible ferro-elastic alpha/beta transition is of first order. It\nis accompanied by a large volume discontinuity of about 5% and a coexistence\nregion of the two phases. A gliding mechanism of {001} bilayers along one of\nthe cubic <110>-directions governs the phase transition which can be described\nin terms of group/subgroup relationships via a common subgroup, despite its\nreconstructive character. The quadrupling of the primitive unit cell indicates\na wave vector (0,0,pi/a) on the Delta-line of the Brillouin zone.",
        "positive": "Anomalous sign inversion of spin-orbit torque in\n  ferromagnetic/nonmagnetic bilayer systems due to self-induced spin-orbit\n  torque: Self-induced spin-orbit torques (SI-SOTs) in ferromagnetic (FM) layers have\nbeen overlooked when estimating the spin Hall angle (SHA) of adjacent\nnonmagnetic (NM) layers. In this work, we observe anomalous sign inversion of\nthe total SOT in the spin-torque ferromagnetic resonance due to the enhanced\nSI-SOT, and successfully rationalize the sign inversion through a theoretical\ncalculation considering the SHE in both the NM and FM layers. The findings show\nthat using an FM layer whose SHA sign is the same as that of the NM achieves\nefficient SOT-magnetization switching with the assistance of the SI-SOT. The\ncontribution of the SI-SOT becomes salient for a weakly conductive NM layer,\nand conventional analyses that do not consider the SI-SOT can overestimate the\nSHA of the NM layer by a factor of more than 150."
    },
    {
        "anchor": "Electrodynamic Response and Stability of Molecular Crystals: We show that electrodynamic dipolar interactions, responsible for long-range\nfluctuations in matter, play a significant role in the stability of molecular\ncrystals. Density functional theory calculations with van der Waals\ninteractions determined from a semilocal \"atom-in-a-molecule\" model result in a\nlarge overestimation of the dielectric constants and sublimation enthalpies for\npolyacene crystals from naphthalene to pentacene, whereas an accurate treatment\nof non-local electrodynamic response leads to an agreement with the measured\nvalues for both quantities. Our findings suggest that collective response\neffects play a substantial role not only for optical excitations, but also for\ncohesive properties of non-covalently bound molecular crystals.",
        "positive": "Asymmetric Pt/Co/Pt structure as a platform for extracting pure spin\n  Hall torque: We have quantitatively studied the spin-orbit torque purely generated by the\nspin Hall effect in a wide range of temperatures by intensionally eliminating\nthe Rashba spin-orbit torque using Pt/Co/Pt trilayers with asymmetric\nthicknesses of the top and bottom Pt layers. The vanishingly small contribution\nfrom the Rashba effect has been confirmed through the vector measurements of\nthe current-induced effective fields. In order to precisely determine the value\nof the spin Hall torque, the complete cancelation of the spin Hall torque has\nbeen verified by fabricating symmetric Pt/Co/Pt structure on SiO2 and Gd3Ga5O12\n(GGG) substrates. Despite of the complete cance- lation on the GGG substrate,\nthe spin Hall torque cannot be completely canceled out even when the top and\nbottom Pt layers have same thicknesses on the SiO2 substrate, which suggests\nthat Pt/Co/Pt trilayers on a GGG substrate is a suitable system for precise\nmeasurements of the spin Hall torque. The result of the vector measurements on\nPt/Co/Pt/GGG from 300 to 10 K shows that the spin Hall torque is almost\nindependent of temperature, which is quantitatively reproduced under the\nassumption of the temperature-independent spin Hall angle of Pt."
    },
    {
        "anchor": "Thermal evolution of silicon carbide electronic bands: Direct observation of temperature dependence of individual bands of\nsemiconductors for a wide temperature region is not straightforward, in\nparticular. However, this fundamental property is a prerequisite in\nunderstanding the electron-phonon coupling of semiconductors. Here we apply\n\\emph{ab initio} many body perturbation theory to the electron-phonon coupling\non hexagonal silicon carbide (SiC) crystals and determine the temperature\ndependence of the bands. We find a significant electron-phonon renormalization\nof the band gap at 0~K. Both the conduction and valence bands shift at elevated\ntemperatures exhibiting a different behavior. We compare our theoretical\nresults with the observed thermal evolution of SiC band edges, and discuss our\nfindings in the light of high temperature SiC electronics and defect qubits\noperation.",
        "positive": "Dirac Material Graphene: The paper presents the author view on spin-rooted properties of graphene\nsupported by numerous experimental and calculation evidences. Dirac fermions of\ncrystalline graphene and local spins of graphene molecules are suggested to\nmeet a strict demand - different orbitals for different spins- which leads to a\nlarge spectrum of effects caused by spin polarization of electronic states. The\nconsequent topological non-triviality, making graphene topological insulator,\nand local spins, imaging graphene chemical activity, are proposed to discuss\nsuch peculiar properties of graphene as high temperature ferromagnetism and\noutstanding chemical behavior. The connection of these new findings with\ndifficulties met at attempting to convert semimetal graphene into semiconductor\none is discussed."
    },
    {
        "anchor": "Anomalous effects in conductivity of thin film samples obtained by\n  thermolysis of PVC in solution: It was stated earlier that in the samples of PVC films plasticized by a new\ntype of plasticizer (modifier-A) abnormal transitions are possible from the\nstate of low electrical conductivity to the state of high conductivity. For the\nfirst time a similar anomalous transition is demonstrated in thin-film samples\nof (partially dehydrochlorinated) PVC obtained by thermolysis in solution,\nwithout use of any special additives, plasticizers, ionizing radiation, etc.\n  Anomalous effects of conductivity in the experimental data obtained clearly\ncorrelate with a concentration of conjugated double bonds (polyvinylen\nfragments) in the main chain of thermalized PVC macromolecules.",
        "positive": "The Kinetics of Primary Alpha Plate Growth in Titanium Alloys: The kinetics of primary alpha-Ti colony/Widmanstatten plate growth from the\nbeta are examined, comparing model to experiment. The plate growth velocity\ndepends sensitively both on the diffusivity D(T) of the rate-limiting species\nand on the supersaturation around the growing plate. These result in a maxima\nin growth velocity around 40 K below the transus, once sufficient\nsupersaturation is available to drive plate growth. In Ti-6246, the plate\ngrowth velocity was found to be around 0.32 um min-1 at 850 oC, which was in\ngood agreement with the model prediction of 0.36 um min-1 . The solute field\naround the growing plates, and the plate thickness, was found to be quite\nvariable, due to the intergrowth of plates and soft impingement. This solute\nfield was found to extend to up to 30 nm, and the interface concentration in\nthe beta was found to be around 6.4 at.% Mo. It was found that increasing O\ncontent will have minimal effect on the plate lengths expected during\ncontinuous cooling; in contrast, Mo approximately doubles the plate lengths\nobtained for every 2 wt.% Mo reduction. Alloys using V as the beta stabiliser\ninstead of Mo are expected to have much faster plate growth kinetics at\nnominally equivalent V contents. These findings will provide a useful tool for\nthe integrated design of alloys and process routes to achieve tailored\nmicrostructures."
    },
    {
        "anchor": "Thermodynamic ground states of platinum metal nitrides: The thermodynamic stabilities of various phases of the nitrides of the\nplatinum metal elements are systematically studied using density functional\ntheory. It is shown that for the nitrides of Rh, Pd, Ir and Pt two new crystal\nstructures, in which the metal ions occupy simple tetragonal lattice sites,\nhave lower formation enthalpies at ambient conditions than any previously\nproposed structures. The region of stability with respect to those structures\nextends to 17 GPa for PtN2. Calculations show that the PtN2 simple tetragonal\nstructures at this pressure are thermodynamically stable also with respect to\nphase separation. The fact that the local density and generalized gradient\napproximations predict different values of the absolute formation enthalpies as\nwell different relative stabilities between simple tetragonal and the pyrite or\nmarcasite structures are further discussed.",
        "positive": "Influence of s-d interfacial scattering on the magnetoresistance of\n  magnetic tunnel junctions: We propose the two-band s-d model to describe theoretically a diffuse regime\nof the spin-dependent electron transport in magnetic tunnel junctions (MTJ's)\nof the form F/O/F where F's are 3d transition metal ferromagnetic layers and O\nis the insulating spacer. We aim to explain the strong interface sensitivity of\nthe tunneling properties of MTJ's and investigate the influence of electron\nscattering at the nonideal interfaces on the degradation of the TMR magnitude.\nThe generalized Kubo formalism and the Green's functions method were used to\ncalculate the conductance of the system. The vertex corrections to the\nconductivity were found with the use of \"ladder\" approximation combined with\nthe coherent-potential approximation (CPA) that allowed to consider the case of\nstrong electron scattering. It is shown that the Ward identity is satisfied in\nthe framework of this approximation that provides the necessary condition for a\nconservation of a tunneling current. Based on the known results of ab-initio\ncalculations of the TMR for ballistic junctions, we assume that exchange split\nquasi-free s-like electrons with the density of states being greater for the\nmajority spin sub-band give the main contribution to the TMR effect. We show\nthat, due to interfacial inter-band scattering, the TMR can be substantially\nreduced even down to zero value. This is related to the fact that delocalized\nquasi-free electrons can scatter into the strongly localized d sub-band with\nthe density of states at the Fermi energy being larger for minority spins\ncompared to majority spins. It is also shown that spin-flip electron scattering\non the surface magnons within the interface leads to a further decrease of the\nTMR at finite temperature."
    },
    {
        "anchor": "Mathematical theory of diffusion in solids: solutions in the\n  semi-infinite body and solution to a diffusion problem with a variable\n  boundary condition: A review of solutions of solid-state diffusion problems in infinite and\nsemi-infinite bodies is presented. Based on the identified solutions for the\nsemi-infinite body a two-step diffusion problem is discussed in detail with the\nfirst step characterized by a Dirichlet constant concentration condition and\nthe second step by a Neumann condition.",
        "positive": "First-principles LDA+U and GGA+U study of neptunium dioxide: We have performed a systematic first-principles investigation to calculate\nthe electronic structures, mechanical properties, and phonon dispersion curves\nof NpO$_{2}$. The local density approximation$+U$ and the generalized gradient\napproximation$+U$ formalisms have been used to account for the strong on-site\nCoulomb repulsion among the localized Np $5f$ electrons. By choosing the\nHubbard \\emph{U} parameter around 4 eV, the orbital occupancy characters of Np\n5\\emph{f} and O 2\\emph{p} are in good agreement with recent experiments [J.\nNucl. Mater. \\textbf{389}, 470 (2009)]. Comparing with our previous study of\nThO$_{2}$, we note that stronger covalency exists in NpO$_{2}$ due to the more\nlocalization behavior of 5\\emph{f} electrons of Np in line with the\nlocalization-delocalization trend exhibited by the actinides series."
    },
    {
        "anchor": "Electronic structure and magnetism in doped semiconducting half-Heusler\n  compounds: We have studied in details the electronic structure and magnetism in M (Mn\nand Cr) doped semiconducting half-Heusler compounds FeVSb, CoTiSb and NiTiSn\n(XM$_{x}$Y$_{1-x}$Z) in a wide concentration range using local-spin density\nfunctional method in the framework of tight-binding linearized muffin tin\norbital method(TB-LMTO) and supercell approach. Our calculations indicate that\nsome of these compounds are not only ferromagnetic but also half-metallic and\nmay be useful for spintronics applications. The electronic structure of the\ndoped systems is analyzed with the aid of a simple model where we have\nconsidered the interaction between the dopant transition metal (M) and the\nvalence band X-Z hybrid. We have shown that the strong X-d - M-d interaction\nplaces the M-d states close to the Fermi level with the M-t$_{2g}$ states lying\nhigher in energy in comparison to the M-e$_{g}$ states. Depending on the number\nof available d-electrons, ferromagnetism is realized provided the d-manifold is\npartially occupied. The tendencies toward ferromagnetic(FM) or\nantiferromagnetic(AFM) behavior are discussed within Anderson-Hasegawa models\nof super-exchange and double-exchange. In our calculations for Mn doped NiTiSn,\nthe strong preference for FM over AFM ordering suggests a possible high Curie\ntemperature for these systems.",
        "positive": "Magnetic phase transitions in Ta/CoFeB/MgO multilayers: We study thin films and magnetic tunnel junction nanopillars based on\nTa/Co$_{20}$Fe$_{60}$B$_{20}$/MgO multilayers by electrical transport and\nmagnetometry measurements. These measurements suggest that an ultrathin\nmagnetic oxide layer forms at the Co$_{20}$Fe$_{60}$B$_{20}$/MgO interface. At\napproximately 160 K, the oxide undergoes a phase transition from an insulating\nantiferromagnet at low temperatures to a conductive weak ferromagnet at high\ntemperatures. This interfacial magnetic oxide is expected to have significant\nimpact on the magnetic properties of CoFeB-based multilayers used in spin\ntorque memories."
    },
    {
        "anchor": "Bosonic behavior of excitons and screening: a consistent calculation: Excitons have recently been shown to deviate from pure bosons at densities a\nhundred times smaller than the Mott density. The corresponding calculations\nrelied on the unscreened excitonic ground state wavefunction. A consistent\ninclusion of screening, by use of the fundamental eigenfunction of the\nHulth\\'{e}n potential, vindicates this approximation.",
        "positive": "This paper as been withdrawn: This paper as been withdrawn. This paper as been withdrawn. This paper as\nbeen withdrawn. This paper as been withdrawn. This paper as been withdrawn.\nThis paper as been withdrawn."
    },
    {
        "anchor": "Spatially uniform resistance switching of low current, high endurance\n  titanium-niobium-oxide memristors: We analyzed micrometer-scale titanium-niobium-oxide prototype memristors,\nwhich exhibited low write-power (<3 {\\mu}W) and energy (<200 fJ/bit/{\\mu}m2),\nlow read-power (~nW), and high endurance (>millions of cycles). To understand\ntheir physico-chemical operating mechanisms, we performed in-operando\nsynchrotron x-ray transmission nanoscale spectromicroscopy using an\nultra-sensitive time-multiplexed technique. We observed only spatially uniform\nmaterial changes during cell operation, in sharp contrast to the frequently\ndetected formation of a localized conduction channel in transition-metal-oxide\nmemristors. We also associated the response of assigned spectral features\ndistinctly to non-volatile storage (resistance change) and writing of\ninformation (application of voltage and Joule heating). These results provide\ncritical insights into high-performance memristors that will aid in device\ndesign, scaling and predictive circuit-modeling, all of which are essential for\nthe widespread deployment of successful memristor applications.",
        "positive": "Influence of strain on magnetization and magnetoelectric effect in\n  La0.7A0.3MnO3 / PMN-PT(001) (A = Sr; Ca): We investigate the influence of a well-defined reversible biaxial strain\n<=0.12 % on the magnetization (M) of epitaxial ferromagnetic manganite films. M\nhas been recorded depending on temperature, strain and magnetic field in 20 -\n50 nm thick films. This is accomplished by reversibly compressing the isotropic\nin-plane lattice parameter of the rhombohedral piezoelectric 0.72PMN-0.28PT\n(001) substrates by application of an electric field E <= 12 kV cm-1. The\nmagnitude of the total variable in-plane strain has been derived.\nStrain-induced shifts of the ferromagnetic Curie temperature (Tc) of up to 19 K\nwere found in La0.7Sr0.3MnO3 (LSMO) and La0.7Ca0.3MnO3 films and are\nquantitatively analysed for LSMO within a cubic model. The observed large\nmagnetoelectric coupling coefficient alpha=mu0 dM/dE <= 6 10-8 s m-1 at ambient\ntemperature results from the strain-induced M change in the\nmagnetic-film-ferroelectric-substrate system. It corresponds to an enhancement\nof mu0 DeltaM <= 19 mT upon biaxial compression of 0.1 %. The extraordinary\nlarge alpha originates from the combination of three crucial properties: (i)\nthe strong strain dependence of M in the ferromagnetic manganites, (ii) large\npiezo-strain of the PMN-PT substrates and (iii) effective elastic coupling at\nthe film-substrate interface."
    },
    {
        "anchor": "Hole-mediated ferromagnetism in tetrahedrally coordinated semiconductors: A mean field model of ferromagnetism mediated by delocalized or weakly\nlocalized holes in zinc-blende and wurzite diluted magnetic semiconductors is\npresented. The model takes into account: (i) strong spin-orbit and kp couplings\nin the valence band; (ii) the effect of strain upon the hole density-of-states,\nand (iii) the influence of disorder and carrier-carrier interactions,\nparticularly near the metal-to-insulator transition. A quantitative comparison\nbetween experimental and theoretical results for (Ga,Mn)As demonstrates that\ntheory describes the values of the Curie temperatures observed in the studied\nsystems as well as explain the directions of the easy axis and the magnitudes\nof the corresponding anisotropy fields as a function of biaxial strain.\nFurthermore, the model reproduces unusual sign, magnitude, and temperature\ndependence of magnetic circular dichroism in the spectral region of the\nfundamental absorption edge. Chemical trends and various suggestions concerning\ndesign of novel ferromagnetic semiconductor systems are described.",
        "positive": "In situ characterisation of nanoscale electromechanical properties of\n  quasi-two-dimensional MoS2 and MoO3: Precise manipulation of electronic band structures of two-dimensional (2D)\ntransition metal dichalcogenides and oxides (TMD&Os) via localised strain\nengineering is an exciting avenue for exploiting their unique characteristics\nfor electronics, optoelectronics, and nanoelectromechanical systems (NEMS)\napplications. This work experimentally demonstrates that mechanically-induced\nelectrical transitions can be engineered in quasi-2D molybdenum disulphide\n(MoS2) and molybdenum trioxide (MoO3) using an in situ electrical\nnanoindentation technique. It is shown that localised strains on such quasi-2D\nlayers can induce carrier transport alterations, thereby changing their\nelectrical conduction behaviour. Such strain effects offer a potential tool for\nprecisely manipulating the electronic transport properties of 2D TMD&Os, and\nunderstanding the interactions of the atomic electronic states in such layered\nmaterials."
    },
    {
        "anchor": "A carbon-nanofiber glass composite with high electrical conductivity: The use of oxide glasses is pervasive throughout everyday amenities and\ncommodities. Such glasses are typically electrical insulators, and endowing\nthem with electrical conductivity without changing their salutary mechanical\nproperties, weight, or thermoformability enables new applications in\nmultifunctional utensils, smart windows, and automotive parts. Previous\nstrategies to impart electrical conductivity include modifying the glass\ncomposition or forming a solid-in-solid composite of the glass and a conductive\nphase. Here we demonstrate using the latter strategy the highest reported\nroom-temperature electrical conductivity in a bulk oxide glass 1800 S/m\ncorresponding to the theoretical limit for the loading fraction of the\nconductive phase. This is achieved through glass-sintering of a mixture of\ncarbon nanofibers and oxide flint F2 or soda lime glasses, with the bulk\nconductivity further enhanced by a polyethylene-block-poly(ethylene glycol)\nadditive. A theoretical model provides predictions that are in excellent\nagreement with the dependence of conductivity of these composites on the\ncarbon-loading fraction. Moreover, nanoscale electrical characterization of the\ncomposite samples provides evidence for the existence of a connected network of\ncarbon nanofibers throughout the bulk. Our results establish a potentially\nlow-cost approach for producing large volumes of highly conductive glass\nindependently of the glass composition.",
        "positive": "High-pressure CaF2 revisited: a new high-temperature phase and the role\n  of phonons in the search for superionic conductivity: We recently proposed a high-pressure and high-temperature P-62m-symmetry\npolymorph for CaF2 on the basis of ab-initio random structure searching and\ndensity-functional theory calculations [Phys. Rev. B 95, 054118 (2017)]. We\nrevisit this polymorph using both ab-initio and classical molecular dynamics\nsimulations. The structure undergoes a phase transition to a superionic phase\nin which calcium ions lie on a bcc-symmetry lattice (space group Im-3m), a\nphase not previously discussed for the group-II difluorides. We demonstrate\nthat modelling this phase transition is surprisingly difficult, and requires\nvery large simulation cells (at least 864 atoms) in order to observe correct\nqualitative and quantitative behaviour. The prediction of superionic behaviour\nin P-62m-CaF2 was originally made through the observation of a lattice\ninstability at the harmonic level in DFT calculations. Using superionic\nalpha-CaF2, CeO2, beta-PbF2 and Li2O as examples, we examine the potential of\nusing phonons as a means to search for superionic materials, and propose that\nthis offers an affordable way to do so."
    },
    {
        "anchor": "Kinetically-stabilized Ferroelectricity in Bulk Singlecrystalline HfO2:Y\n  without Wake-up Effects: HfO2, a simple binary oxide, holds ultra-scalable ferroelectricity integrable\ninto silicon technology. Polar orthorhombic (Pbc21) form in ultra-thin-films\nascribes as the plausible root-cause of the astonishing ferroelectricity, which\nhas thought not attainable in bulk crystals. Though, perplexities remain\nprimarily due to the polymorphic nature and the characterization challenges at\nsmall-length scales. Herein, utilizing a state-of-the-art Laser-Diode-heated\nFloating Zone technique, we report ferroelectricity in bulk single-crystalline\nHfO2:Y as well as the presence of anti-polar Pbca phase at different Y\nconcentrations. Neutron diffraction and atomic imaging demonstrate (anti-)polar\ncrystallographic signatures and abundant 90o/180o ferroelectric domains in\naddition to the switchable polarization with little wake-up effects.\nDensity-functional theory calculations suggest that the Yttrium doping and\nrapid cooling are the key factors for the desired phase. Our observations\nprovide new insights into the polymorphic nature and phase controlling of HfO2,\nremove the upper size limit for ferroelectricity, and also pave a new road\ntoward the next-generation ferroelectric devices.",
        "positive": "Fracture Toughness of Metallic Glasses: Ductile-to-Brittle Transition?: Quantitative understanding of the fracture toughness of metallic glasses,\nincluding the associated ductile-to-brittle transitions, is not yet available.\nHere we use a simple model of plastic deformation in glasses, coupled to an\nadvanced Eulerian level set formulation for solving complex free boundary\nproblems, to calculate the fracture toughness of metallic glasses as a function\nof the degree of structural relaxation corresponding to different annealing\ntimes near the glass temperature. Our main result indicates the existence of an\nelasto-plastic crack tip instability for sufficiently relaxed glasses,\nresulting in a marked drop in the toughness, which we interpret as a\nductile-to-brittle transition similar to experimental observations."
    },
    {
        "anchor": "A Method for Predicting Nonequilibrium Thermal Expansion Using\n  Steepest-Entropy-Ascent Quantum Thermodynamics: Steepest-entropy-ascent quantum thermodynamics (SEAQT) is an intriguing\napproach that describes equilibrium and dynamic processes in a self-consistent\nway. The applicability is limited to mainly gas phases because of a complex\neigenstructure (eigenvalues and eigenfunctions) of solid or liquid phases. In\nthis contribution, the SEAQT modeling is extended to a condensed phase by\nconstructing a simplified eigenstructure (so-called pseudo-eigenstructure), and\nthe applicability is demonstrated by calculating the thermal expansion of\nmetallic silver in three cases: (a) at stable equilibrium, (b) along three\nirreversible paths from an initial nonequilibrium state to stable equilibrium,\nand (c) along an irreversible path between two stable equilibrium states. The\nSEAQT framework with an anharmonic pseudo-eigenstructure predicts reasonable\nvalues for equilibrium thermal expansion. For the irreversible cases\nconsidered, the SEAQT approach makes it possible to predict the time-dependence\nof lattice relaxations from the initial state to the final state.",
        "positive": "Density-based crystal plasticity : from the discrete to the continuum: Because of the enormous range of time and space scales involved in\ndislocation dynamics, plastic modeling at macroscale requires a continuous\nformulation. In this paper, we present a rigorous formulation of the transition\nbetween the discrete, where plastic flow is resolved at the scale of individual\ndislocations, and the continuum, where dislocations are represented by\ndensities. First, we focus on the underlying coarse-graining procedure and show\nthat the emerging correlation-induced stresses are scale-dependent. Each of\nthese stresses can be expanded into the sum of two components. The first one\ndepends on the local values of the dislocation densities and always opposes the\nsum of the applied stress and long-range mean field stress generated by the\ngeometrically necessary dislocation (GND) density; this stress acts as a\nfriction stress. The second component depends on the local gradients of the\ndislocation densities and is inherently associated to a translation of the\nelastic domain; therefore, it acts as a back-stress. We also show that these\nfriction and back- stresses contain symmetry-breaking components that make the\nlocal stress experienced by dislocations to depend on the sign of their Burgers\nvector."
    },
    {
        "anchor": "Molecular pillar approach to grow vertical covalent organic framework\n  nanosheets on graphene: new hybrid materials for energy storage: Hybrid 2D-2D materials composed by perpendicularly oriented covalent organic\nframework (COFs) and graphene were prepared and tested for energy storage\napplications. Diboronic acid molecules covalently attached to graphene oxide\n(GO) were used as nucleation sites for directing vertical growth of COF-1\nnanosheets (v-COF-GO). The hybrid material shows forest of COF-1 nanosheets\nwith thickness of ~3 to 15 nm in edge-on orientation relative to GO. The same\nreaction performed in absence of molecular pillars resulted in uncontrollable\ngrowth of thick COF-1 platelets parallel to the surface of GO. The v-COF-GO was\nconverted into conductive carbon material preserving the nanostructure of\nprecursor with ultrathin porous carbon nanosheets grafted to graphene in\nedge-on orientation. It was demonstrated as high-performance electrode material\nfor supercapacitors. The molecular pillar approach can be used for preparation\nof many other 2D-2D materials with control of their relative orientation.",
        "positive": "Second harmonic microscopy of monolayer MoS2: We show that the lack of inversion symmetry in monolayer MoS2 allows strong\noptical second harmonic generation. Second harmonic of an 810-nm pulse is\ngenerated in a mechanically exfoliated monolayer, with a nonlinear\nsusceptibility on the order of 1E-7 m/V. The susceptibility reduces by a factor\nof seven in trilayers, and by about two orders of magnitude in even layers. A\nproof-of-principle second harmonic microscopy measurement is performed on\nsamples grown by chemical vapor deposition, which illustrates potential\napplications of this effect in fast and non-invasive detection of crystalline\norientation, thickness uniformity, layer stacking, and single-crystal domain\nsize of atomically thin films of MoS2 and similar materials."
    },
    {
        "anchor": "High-Pressure Synthesis of a Pentazolate Salt: The pentazolates, the last all-nitrogen members of the azole series, have\nbeen notoriously elusive for the last hundred years despite enormous efforts to\nmake these compounds in either gas or condensed phases. Here we report a\nsuccessful synthesis of a solid state compound consisting of isolated\npentazolate anions N5-, which is achieved by compressing and laser heating\ncesium azide (CsN3) mixed with N2 cryogenic liquid in a diamond anvil cell. The\nexperiment was guided by theory, which predicted the transformation of the\nmixture at high pressures to a new compound, cesium pentazolate salt (CsN5).\nElectron transfer from Cs atoms to N5 rings enables both aromaticity in the\npentazolates as well as ionic bonding in the CsN5 crystal. This work provides a\ncritical insight into the role of extreme conditions in exploring unusual\nbonding routes that ultimately lead to the formation of novel high nitrogen\ncontent species.",
        "positive": "Levy Flight of Photoexcited Minority Carriers in Moderately Doped\n  Semiconductors: Theory and Observation: Spatial spread of minority carriers produced by optical excitation in\nsemiconductors is usually well described by a diffusion equation. The classical\ndiffusion process can be viewed as a result of a random walk of particles in\nwhich every step has the same probability distribution with a finite second\nmoment. This allows applying the central limit theorem to the calculation of\nthe particle distribution after many steps. However, in moderately doped\ndirect-gap semiconductors the photon recycling process can radically modify the\nspatial spread. For this process, the steps in the random walk are defined by\nthe reabsorption length of photons produced in radiative recombination. The\nstep distribution has an asymptotic power-law decline. Moments of this\ndistribution diverge and the displacement is governed by rare but large steps.\nRandom walk of this kind is called the Levy flight. It corresponds to an\nanomalously large spread in space and a modified (\"super-diffusive\") temporal\nevolution. Here we discuss the first direct observation of the hole profile in\nn-doped InP samples over distances of the order of a centimeter and more than\ntwo orders of magnitude in hole concentration. Luminescence spectra and\nintensity were studied as a function of distance from the photo-excitation in a\nrather unusual geometry (homogeneous excitation of the wafer edge and\nobservation of the luminescence spectra from the broadside). The intensity is\nproportional to the minority-carrier concentration and exhibits a slow\npower-law drop-off with no changes in the spectral shape. This power law gives\na direct evidence of Levy-flight transport. It has enabled us to evaluate the\nindex of the distribution, the characteristic distance of the minority-carrier\nspread and the photon recycling factor. The results are in good agreement with\nthe theoretical analysis."
    },
    {
        "anchor": "Volume Contraction at a Grain Boundary in Vanadium: It is a conventional wisdom that symmetry breakdown at grain boundaries in\ncrystals introduces volume expansion and there has been no confirmed evidence\nof volume contraction at a grain boundary in any kind of crystals. We report\nsurprising volume contraction at the Sigma3(111) grain boundary in vanadium.\nThe lattice distortion near this grain boundary is found to drive the local\nstructure toward a hypothetical {\\omega} phase, which is only slightly less\nstable than the bcc phase. Compressing lattice constant a of the {\\omega}-phase\ndown to the value of bcc, as is the case at the Sigma3(111) grain boundary,\nresults in smaller c than in bcc structure, and hence the volume contraction.\nWe also find such a volume contraction impedes the segregation of Ti and H,\nwhile enhances that of Cr, and hence a significant influence on material\nproperties. The discovery adds fundamental new knowledge of condensed matter,\nand may also point to new techniques in grain boundary engineering of novel\nmaterials through volume control.",
        "positive": "Atomistic simulations of the interaction of basal dislocations with\n  MgZn$_2$ precipitates in Mg alloys: The interaction between Mg edge basal dislocations and rod-shaped\n$\\beta_1'$-MgZn$_2$ precipitates was studied by atomistic simulations using a\nnew interatomic potential. The atomistic model was carefully built taking into\naccount the experimental information about the orientation relationship between\nthe matrix and the precipitate to ensure minimum energy interfaces. It was\nfound that the dislocations initially overcame the precipitate by the formation\nof an Orowan loop that penetrated in the precipitate. The precipitate was\nfinally sheared after several Orowan loops were piled-up. The number of loops\nnecessary to shear the precipitate decreased as precipitate cross-section\ndecreased and the temperature increased but was independent of the precipitate\nspacing. Precipitate shearing did not take place along well-defined\ncrystallographic planes but it was triggered by the accumulation of the elastic\nenergy in the precipitate which finally led to formation of an amorphous layer\nbelow and above the slip plane of the basal dislocations. The kink induced in\nthe precipitate by this mechanism was in good agreement with transmission\nelectron microscopy observations."
    },
    {
        "anchor": "The valley Nernst effect in WSe$_2$: The Hall effect can be extended by inducing a temperature gradient in lieu of\nelectric field that is known as the Nernst (-Ettingshausen) effect. The\nrecently discovered spin Nernst effect in heavy metals continues to enrich the\npicture of Nernst effect-related phenomena. However, the collection would not\nbe complete without mentioning the valley degree of freedom benchmarked by the\nobservation of the valley Hall effect. Here we show the experimental evidence\nof its missing counterpart, the valley Nernst effect. Using millimeter-sized\nWSe$_{2}$ mono-multi-layers and the ferromagnetic resonance-spin pumping\ntechnique, we are able to apply a temperature gradient by off-centering the\nsample in the radio frequency cavity and address a single valley through\nspin-valley coupling. The combination of a temperature gradient and the valley\npolarization leads to the valley Nernst effect in WSe$_{2}$ that we detect\nelectrically at room temperature. The valley Nernst coefficient is in very good\nagreement with the predicted value.",
        "positive": "Unchanged thermopower enhancement at the semiconductor-metal transition\n  in correlated FeSb$_{2-x}$Te$_x$: Substitution of Sb in FeSb$_2$ by less than 0.5% of Te induces a transition\nfrom a correlated semiconductor to an unconventional metal with large effective\ncharge carrier mass $m^*$. Spanning the entire range of the semiconductor-metal\ncrossover, we observed an almost constant enhancement of the measured\nthermopower compared to that estimated by the classical theory of electron\ndiffusion. Using the latter for a quantitative description one has to employ an\nenhancement factor of 10-30. Our observations point to the importance of\nelectron-electron correlations in the thermal transport of FeSb$_2$, and\nsuggest a route to design thermoelectric materials for cryogenic applications."
    },
    {
        "anchor": "Adiabatic-connection fluctuation-dissipation density-functional theory\n  based on range separation: An adiabatic-connection fluctuation-dissipation theorem approach based on a\nrange separation of electron-electron interactions is proposed. It involves a\nrigorous combination of short-range density functional and long-range random\nphase approximations. This method corrects several shortcomings of the standard\nrandom phase approximation and it is particularly well suited for describing\nweakly-bound van der Waals systems, as demonstrated on the challenging cases of\nthe dimers Be$_2$ and Ne$_2$.",
        "positive": "Large cross-polarized Raman signal in CrI$_3$: A first-principles study: We find unusually large cross-polarized (and anti-symmetric) Raman signature\nof A$_{\\rm g}$ phonon mode in CrI$_3$, in agreement with experiments. The\nsignal is present only when the following three effects are considered in\nconcert: ferromagnetism on Cr atoms, spin-orbit interaction, and resonant\neffects. Somewhat surprisingly, we find that the relevant spin-orbit\ninteraction potential originates from iodine atoms, despite magnetism being\nmostly on chromium atoms. We analyze the Raman signature as a function of\nmagnetic order, the direction of the magnetic moment, energy and polarization\nof light used for Raman scattering, as well as carrier lifetime. In addition to\na strong cross-polarized Raman signal, we also find unusually strong phonon\nmodulated magneto-optical Kerr effect (MOKE) in CrI$_3$."
    },
    {
        "anchor": "Influence of point defects on the electronic and topological properties\n  of monolayer WTe$_2$: In some topological insulators, such as graphene and WTe$_2$, band inversion\noriginates from chemical bonding and space group symmetry, in contrast to\nmaterials such as Bi$_2$Se$_3$, where the band inversion derives from\nrelativistic effects in the atoms. In the former, band inversion is susceptible\nto changes of the chemical environment, e.g. by defects, while the latter are\nless affected by defects due to the larger energy scale associated with atomic\nrelativistic effects. Motivated by recent experiments, we study the effect of\nTe-vacancies and Te-adatoms on the electronic properties of WTe$_2$. We find\nthat the Te-vacancies have a formation energy of $2.21$ eV, while the formation\nenergy of the Te-adatoms is much lower with $0.72$ eV. The vacancies strongly\ninfluence the band structure and we present evidence that band inversion is\nalready reversed at the nominal composition of WTe$_{1.97}$. In contrast, we\nshow that the adatoms do not change the electronic structure in the vicinity of\nthe Fermi level and thus the topological properties. Our findings indicate that\nTe-adatoms should be present in thin films that are grown in a Te-rich\nenvironment, and we suggest that they have been observed in scanning tunneling\nmicroscopy experiments.",
        "positive": "Optical Determination of Electron-Phonon Coupling in Carbon Nanotubes: We report on an optical method to directly measure electron-phonon coupling\nin carbon nanotubes by correlating the first and second harmonic of the\nresonant Raman excitation profile. The method is applicable to 1D and 0D\nsystems and is not limited to materials that exhibit photoluminescence.\nExperimental results for electron-phonon coupling with the radial breathing\nmode in 5 different nanotubes show coupling strengths from 3-11 meV, depending\non chirality. The results are in good agreement with the chirality and diameter\ndependence calculated by Goupalov et al."
    },
    {
        "anchor": "Contrary Effect of B and N Doping into Graphene and Graphene Oxide\n  Heterostructures with MoS$_2$ on Interface Function and Hydrogen Evolution: Molybdenum disulfide (MoS$_2$) attracts attention as a high efficient and low\ncost photocatalyst for hydrogen production, but suffers from low conductance\nand high recombination rate of photo-generated charge carriers. In this work,\nwe investigate the MoS$_2$ heterostructures with graphene variants (GVs),\nincluding graphene, graphene oxide, and their boron- and nitrogen-doped\nvariants, by using first-principles calculations. Systematic comparison between\ngraphene and graphene oxide composites is performed, and contrary effect of B\nand N doping on interface function and hydrogen evolution is clarified. We find\nthat upon the formation of the interfaces some amount of electronic charge\ntransfers from the GV side to the MoS$_2$ layer, inducing the creation of\ninterface dipole and the reduction of work function, which is more pronounced\nin the graphene oxide composites. Moreover, our results reveal that N doping\nenhances the interface functions by forming donor-type interface states,\nwhereas B doping reduces those functions by forming acceptor-type interface\nstates. However, the B-doped systems exhibit lower Gibbs free energy difference\nfor hydrogen adsorption on GV side than the N-doped systems, which deserves\nmuch consideration in the design of new functional photocatalysts.",
        "positive": "Strong anisotropic interaction controls unusual sticking and scattering\n  of CO at Ru(0001): Complete sticking at low incidence energies and broad angular scattering\ndistributions at higher energies are often observed in molecular beam\nexperiments on gas-surface systems which feature a deep chemisorption well and\nlack early reaction barriers. Although CO binds strongly on Ru(0001),\nscattering is characterized by rather narrow angular distributions and sticking\nis incomplete even at low incidence energies. We perform molecular dynamics\nsimulations, accounting for phononic (and electronic) energy loss channels, on\na potential energy surface based on first principles electronic structure\ncalculations that reproduce the molecular beam experiments. We demonstrate that\nthe mentioned unusual behavior is a consequence of a very strong rotational\nanisotropy in the molecule-surface interaction potential. Beyond the\ninterpretation of scattering phenomena, we also discuss implications of our\nresults for the recently proposed role of a precursor state for the desorption\nand scattering of CO from ruthenium."
    },
    {
        "anchor": "Multiscale Computation with Interpolating Wavelets: Multiresolution analyses based upon interpolets, interpolating scaling\nfunctions introduced by Deslauriers and Dubuc, are particularly well-suited to\nphysical applications because they allow exact recovery of the multiresolution\nrepresentation of a function from its sample values on a finite set of points\nin space. We present a detailed study of the application of wavelet concepts to\nphysical problems expressed in such bases. The manuscript describes algorithms\nfor the associated transforms which, for properly constructed grids of variable\nresolution, compute correctly without having to introduce extra grid points. We\ndemonstrate that for the application of local homogeneous operators in such\nbases, the non-standard multiply of Beylkin, Coifman and Rokhlin also proceeds\nexactly for inhomogeneous grids of appropriate form. To obtain less stringent\nconditions on the grids, we generalize the non-standard multiply so that\ncommunication may proceed between non-adjacent levels. The manuscript concludes\nwith timing comparisons against naive algorithms and an illustration of the\nscale-independence of the convergence rate of the conjugate gradient solution\nof Poisson's equation using a simple preconditioning, suggesting that this\napproach leads to an O(n) solution of this equation.",
        "positive": "Enhanced electron correlations in the new binary stannide PdSn4: a\n  homologue of the Dirac nodal arc semimetal PtSn4: The advent of nodal-line semi-metals, i.e. systems in which the conduction\nand valence bands cross each other along a closed trajectory (line or loop)\ninside the Brillouin zone, has opened up a new arena for the exploration of\ntopological condensed matter in which, due to a vanishing density of states\nnear the Fermi level, electron correlation effects may also play an important\nrole. In spite of this conceptual richness however, material realization of\nnodal-line (loop) fermions is rare, with PbTaSe2, ZrSiS and PtSn4 the only\npromising known candidates. Here we report the synthesis and physical\nproperties of a new compound PdSn4 that is isostructural with PtSn4 yet\npossesses quasiparticles with significantly enhanced effective masses. In\naddition, PdSn4 displays an unusual polar angular magnetoresistance which at a\ncertain field orientation, varies linearly with field up to 55 Tesla. Our study\nsuggests that, in association with its homologue PtSn4 whose low-lying\nexcitations were recently claimed to possess Dirac node arcs, PdSn4 may be a\npromising candidate in the search for novel topological states with enhanced\ncorrelation effects."
    },
    {
        "anchor": "Influence of hydrogenation on the vibrational density of states of\n  magnetocaloric\n  $\\mathrm{LaFe}_\\mathrm{11.4}\\mathrm{Si}_\\mathrm{1.6}\\mathrm{H}_{1.6}$: We report on the impact of magnetoelastic coupling on the magnetocaloric\nproperties of LaFe$_{11.4}$Si$_{1.6}$H$_{1.6}$ in terms of the vibrational\ndensity of states, which we determined with $^{57}$Fe nuclear resonant\ninelastic X-ray scattering measurements and with density-functional-theory\nbased first-principles calculations in the ferromagnetic low-temperature and\nparamagnetic high-temperature phase. In experiments and calculations, we\nobserve pronounced differences in the shape of the Fe-partial VDOS between\nnon-hydrogenated and hydrogenated samples. This shows that hydrogen does not\nonly shift the temperature of the first-order phase transition, but also\naffects the elastic response of the Fe-subsystem significantly. In turn, the\nanomalous redshift of the Fe VDOS, observed by going to the low-volume PM\nphase, survives hydrogenation. As a consequence, the change in the Fe specific\nvibrational entropy $\\Delta S_\\mathrm{lat}$ across the phase transition has the\nsame sign as the magnetic and electronic contribution. DFT calculations show\nthat the same mechanism, which is a consequence of the itinerant electron\nmetamagnetism associated with the Fe subsystem, is effective in both the\nhydrogenated and he hydrogen-free compounds. Although reduced by 50 % as\ncompared to the hydrogen-free system, the measured change $\\Delta\nS_\\mathrm{lat}$ of 3.2\\pm1.9 J/kgK across the FM to PM transition contributes\nwith 35 % significantly and cooperatively to the total isothermal entropy\nchange $\\Delta S_\\mathrm{iso}$. Hydrogenation is observed to induce an overall\nblueshift of the Fe-VDOS with respect to the H-free compound; this effect,\ntogether with the enhanced Debye temperature observed, is a fingerprint of the\nhardening of the Fe sublattice by hydrogen incorporation. In addition, the mean\nDebye velocity of sound of LaFe$_{11.4}$Si$_{1.6}$H$_{1.6}$ was determined from\nthe NRIXS and the DFT data.",
        "positive": "Deep learning analysis of polaritonic waves images: Deep learning (DL) is an emerging analysis tool across sciences and\nengineering. Encouraged by the successes of DL in revealing quantitative trends\nin massive imaging data, we applied this approach to nano-scale deeply\nsub-diffractional images of propagating polaritonic waves in complex materials.\nWe developed a practical protocol for the rapid regression of images that\nquantifies the wavelength and the quality factor of polaritonic waves utilizing\nthe convolutional neural network (CNN). Using simulated near-field images as\ntraining data, the CNN can be made to simultaneously extract polaritonic\ncharacteristics and materials parameters in a timescale that is at least three\norders of magnitude faster than common fitting/processing procedures. The\nCNN-based analysis was validated by examining the experimental near-field\nimages of charge-transfer plasmon polaritons at Graphene/{\\alpha}-RuCl3\ninterfaces. Our work provides a general framework for extracting quantitative\ninformation from images generated with a variety of scanning probe methods."
    },
    {
        "anchor": "Impact of Cr-O hyrbidization in ACrO3 (A=La, Y): A Theoretical\n  Investigation: Electronic properties of spin polarized antiferromagnetic ACrO3 (A = La, Y)\nare explored with Hubbard Model using Density Functional Theory (DFT). These\ntwo isostructural systems are investigated using the different Hubbard energy\nand analyzed the hybridization of chromium 3d orbitals and oxygen 2p orbitals\nand the change in energy band gaps against the Hubbard energy. The bond length\nand bond angle affect significantly the orbital contributions of Cr-3d and O-2p\nelectrons for both the system. We noticed that the Cr-O hybridization affects\nthe orbital degeneracy and is substantiated with partial density of states.\nThese results emphasize the contribution of Hubbard energy in correlated\nelectron systems.",
        "positive": "Role of Berry phase theory for describing orbital magnetism: From\n  magnetic heterostructures to topological orbital ferromagnets: We address the importance of the modern theory of orbital magnetization for\nspintronics. Based on an all-electron first-principles approach, we demonstrate\nthat the predictive power of the routinely employed \"atom-centered\"\napproximation is limited to materials like elemental bulk ferromagnets, while\nthe application of the modern theory of orbital magnetization is crucial in\nchemically or structurally inhomogeneous systems such as magnetic thin films,\nand materials exhibiting non-trivial topology in reciprocal and real\nspace,~e.g.,~Chern insulators or non-collinear systems. We find that the modern\ntheory is particularly crucial for describing magnetism in a class of materials\nthat we suggest here $-$ topological orbital ferromagnets."
    },
    {
        "anchor": "Thermoelectric La-doped SrTiO3 epitaxial layers with single-crystal\n  quality: from nanometer to micrometer and mosaicity effects: High-quality thermoelectric LaxSr1-xTiO3 (LSTO) layers (here with x = 0.2),\nwith thicknesses ranging from 20 nm to 700 nm, have been epitaxially grown on\nSrTiO3(001) substrates by enhanced solid-source oxide molecular-beam epitaxy.\nAll films are atomically flat (with rms roughness < 0.2 nm), with low mosaicity\n(<0.1{\\deg}), and present very low electrical resistivity (<5 x 10-4 ohm.cm at\nroom temperature), one order of magnitude lower than commercial Nb-doped SrTiO3\nsingle-crystalline substrate. The conservation of transport properties within\nthis thickness range has been confirmed by thermoelectric measurements where\nSeebeck coefficients of around -60 microV/K have been found for all films,\naccordingly. Finally, a correlation is given between the mosaicity and the\n(thermo)electric properties. These functional LSTO films can be integrated on\nSi in opto-microelectronic devices as transparent conductor, thermoelectric\nelements or in non-volatile memory structures.",
        "positive": "Effects of applied strain on radiation damage generation in\n  body-centered cubic iron: Radiation damage in body-centered cubic (BCC) Fe has been extensively studied\nby computer simulations to quantify effects of temperature, impinging particle\nenergy, and the presence of extrinsic particles. However, limited investigation\nhas been conducted into the effects of mechanical stresses and strain. In a\nreactor environment, structural materials are often mechanically strained, and\nan expanded understanding of how this strain affects the generation of defects\nmay be important for predicting microstructural evolution and damage\naccumulation under such conditions. In this study, we have performed molecular\ndynamics simulations in which various types of homogeneous strains are applied\nto BCC Fe and the effect on defect generation is examined. It is found that\nvolume-conserving shear strains yield no statistically significant variations\nin the stable number of defects created via cascades in BCC Fe. However,\nstrains that result in volume changes are found to produce significant effects\non defect generation."
    },
    {
        "anchor": "First Principles Studies on 3-Dimentional Strong Topological Insulators:\n  Bi2Te3, Bi2Se3 and Sb2Te3: Bi2Se3, Bi2Te3 and Sb2Te3 compounds are recently predicted to be\n3-dimentional (3D) strong topological insulators. In this paper, based on\nab-initio calculations, we study in detail the topological nature and the\nsurface states of this family compounds. The penetration depth and the\nspin-resolved Fermi surfaces of the surface states will be analyzed. We will\nalso present an procedure, from which highly accurate effective Hamiltonian can\nbe constructed, based on projected atomic Wannier functions (which keep the\nsymmetries of the systems). Such Hamiltonian can be used to study the\nsemi-infinite systems or slab type supercells efficiently. Finally, we discuss\nthe 3D topological phase transition in Sb2(Te1-xSex)3 alloy system.",
        "positive": "Novel dielectric anomalies due to spin-chains above and below Neel\n  temperature in Ca3Co2O6: We bring out novel dielectric behavior of a spin-chain compound, Ca3Co2O6,\nundergoing Neel order at (T_N=) 24 K. It is found that the virgin curve in the\nplot of isothermal dielectric constant versus magnetic-field lies outside the\n'butterfly-shaped' envelope curve well below T_N (e.g., 2.6 K), with a\nsignature of a partial arrest of the high-field magnetoelectric ME) phase in\nzero-field after travelling through magnetic-field-induced magnetic\ntransitions. This behavior is in contrast to that observed in the isothermal\nmagnetization data. Thus, this work brings out a novel case for\n'phase-coexistence phenomenon' due to ME coupling. Another strange finding is\nthat there is a weak, but a broad, peak in dielectric constant around 85 - 115\nK well above T_N, attributable to incipient spin-chain magnetic ordering. This\nfinding should inspire further work to study ME coupling on artificial\nassemblies of magnetic chains, also keeping in mind miniaturization required\nfor possible applications."
    },
    {
        "anchor": "Structural defects induced by Fe-ion implantation in TiO2: X-ray photoelectron spectroscopy (XPS) and resonant x-ray emission\nspectroscopy (RXES) measurements of pellet and thin film forms of TiO$_2$ with\nimplanted Fe ions are presented and discussed. The findings indicate that\nFe-implantation in a TiO$_2$ pellet sample induces heterovalent cation\nsubstitution (Fe$^{2+}\\rightarrow$ Ti$^{4+}$) beneath the surface region. But\nin thin film samples, the clustering of Fe atoms is primarily detected. In\naddition to this, significant amounts of secondary phases of Fe$^{3+}$ are\ndetected on the surface of all doped samples due to oxygen exposure. These\nexperimental findings are compared with density functional theory (DFT)\ncalculations of formation energies for different configurations of structural\ndefects in the implanted TiO$_2$:Fe system. According to our calculations, the\nclustering of Fe-atoms in TiO$_2$:Fe thin films can be attributed to the\nformation of combined substitutional and interstitial defects. Further, the\ndifferences due to Fe doping in pellet and thin film samples can ultimately be\nattributed to different surface to volume ratios.",
        "positive": "A Novel Route for the Inclusion of Metal Dopants in Silicon: We report a new method to introduce metal atoms into silicon wafers, using\nnegligible thermal budget. Molecular thin films are irradiated with\nultra-violet (UV) light releasing metal species into the semiconductor\nsubstrate. Secondary ion mass spectrometry (SIMS) and X-ray absorption\nspectroscopy (XAS) show that Mn is incorporated into Si as an interstitial\ndopant. We propose that our method can form the basis of a generic low-cost,\nlow-temperature technology that could lead to the creation of ordered dopant\narrays."
    },
    {
        "anchor": "Towards intrinsic phonon transport in single-layer MoS$_2$: The intrinsic lattice thermal conductivity of MoS$_2$ is an important aspect\nin the design of MoS$_2$-based nanoelectronic devices. We investigate the\nlattice dynamics properties of MoS$_2$ by first principles calculations. The\nintrinsic thermal conductivity of single-layer MoS$_2$ is calculated using the\nBoltzmann transport equation for phonons. The obtained thermal conductivity\nagrees well with the measurements. The contributions of acoustic and optical\nphonons to the lattice thermal conductivity are evaluated. The size dependence\nof thermal conductivity is investigated as well.",
        "positive": "On the detection of surface spin freezing in iron oxide nanoparticles\n  and its long-term evolution under ambient oxidation: Exchange bias effects linked to surface spin freezing (SSF) are commonly\nfound in iron oxide nanoparticles, while signatures of SSF in low-field\ntemperature-dependent magnetization curves have been much less frequently\nreported. Here, we present magnetic properties of dense assemblies of\nsimilar-sized (~ 8 nm diameter) particles synthesized by a magnetite (sample\nS1) and a maghemite (sample S2) method, and the influence of long-term (4-year)\nsample aging under ambient conditions on these properties. The size of the\nexchange bias field of the different sample (fresh or aged) states is found to\ncorrelate with (a) whether a low-temperature hump feature signaling the SSF\ntransition is detected in out-of-phase ac susceptibility or zero-field-cooled\n(ZFC) dc magnetization recorded at low field and with (b) the prominence of\nirreversibility between FC and ZFC curves recorded at high field. Sample S1\ndisplays a lower magnetization than S2, and it is in S1 where the largest SSF\neffects are found. These effects are significantly weakened by aging but remain\nlarger than the SSF effects in S2, where the influence of aging is considerably\nsmaller. A non-saturating component due to spin disorder in S1 also weakens\nwith aging, accompanied by, we infer, an increase in the superspin and the\nradius of the ordered nanoparticle cores. X-ray diffraction and M\\\"ossbauer\nspectroscopy provide indication of maghemite-like stoichiometry in both aged\nsamples as well as thicker disordered particle shells in aged-S1 relative to\naged-S2 (crystallographically-disordered and spin-disordered according to\ndiffraction and M\\\"ossbauer, respectively). The pronounced diminution in SSF\neffects with aging in S1 is attributed to a (long-term) transition, caused by\nambient oxidation, from magnetite-like to maghemite-like stoichiometry, and a\nconcomitant softening of the spin-disordered shell anisotropy..."
    },
    {
        "anchor": "Optical properties of Bi2Te2Se at ambient and high pressure: The temperature dependence of the complex optical properties of the\nthree-dimensional topological insulator Bi2Te2Se is reported for light\npolarized in the a-b planes at ambient pressure, as well as the effects of\npressure at room temperature. This material displays a semiconducting character\nwith a bulk optical gap of 300 meV at 295 K. In addition to the two expected\ninfrared-active vibrations observed in the planes, there is additional fine\nstructure that is attributed to either the removal of degeneracy or the\nactivation of Raman modes due to disorder. A strong impurity band located at\n200 cm^{-1} is also observed. At and just above the optical gap, several\ninterband absorptions are found to show a strong temperature and pressure\ndependence. As the temperature is lowered these features increase in strength\nand harden. The application of pressure leads to a very abrupt closing of the\ngap above 8 GPa, and strongly modifies the interband absorptions in the\nmid-infrared spectral range. While ab initio calculations fail to predict the\ncollapse of the gap, they do successfully describe the size of the band gap at\nambient pressure, and the magnitude and shape of the optical conductivity.",
        "positive": "Nodal Line Spin-gapless Semimetals and High-quality Candidate Materials: Spin-gapless semimetals (SGSMs), which generate 100\\% spin polarization, are\nviewed as promising semi-half-metals in spintronics with high speed and low\nconsumption. We propose and characterize a new $\\mathbb{Z_{\\mathrm{2}}}$ class\nof topological nodal line (TNL) in SGSMs. The proposed TNLSGSMs are protected\nby space-time inversion symmetry or glide mirror symmetry with two-dimensional\n(2D) fully spin-polarized nearly flat surface states. Based on first-principles\ncalculations and effective model analysis, a series of high-quality materials\nwith $\\textit{R}\\overline{3}\\textit{c}$ and $\\textit{R}{3}\\textit{c}$ space\ngroups are predicted to realize such TNLSGSMs (chainlike). The 2D fully\nspin-polarized nearly flat surface states may provide a route to achieving\nequal spin pairing topological superconductivity as well as topological\ncatalysts."
    },
    {
        "anchor": "X-ray Nano-imaging of a Heterogeneous Structural Phase Transition in\n  V2O3: Controlling the Mott transition through strain engineering is crucial for\nadvancing the development and application of memristive and neuromorphic\ncomputing devices. Yet, Mott insulators are heterogeneous due to intrinsic\nphase boundaries and extrinsic defects, posing significant challenges to fully\nunderstanding the impact of local microscopic distortions on the local Mott\ntransition, which demands structural characterizations at the relevant length\nscale. Here, using a synchrotron-based scanning X-ray nanoprobe, we studied the\nreal-space structural heterogeneity during the structural phase transition in a\nV2O3 thin film, with a resolution of 30 nm. Through temperature-dependent\nmetal-insulator phase coexistence mapping, we report a variation in the local\ntransition temperature of up to 7 K across the film and the presence of the\ntransition hysteresis at the nanoscale. Furthermore, a detailed quantitative\nanalysis demonstrates that the spatial heterogeneity of the transition is\nclosely tied to the tilting of crystallographic planes in the pure insulating\nphase. We develop a structural model allowing us to interpret these tilts as\nvariation of the monoclinic distortion during the rhombohedral-monoclinic phase\ntransition. Our work highlights the impact of local heterogeneous lattice\ndistortions on the Mott transition and lays the groundwork for future\ninnovations in harnessing strain heterogeneity within Mott systems for the\nnext-generation computational technologies.",
        "positive": "Nanoscale Tantalum Layer Controlling the Magnetic Coupling between Two\n  Ferromagnetic Electrodes via Insulator of a Magnetic Tunnel Junction: Ability to tailor the nature of the magnetic coupling between two\nferromagnetic electrodes can enable the realization of new spintronics device\nsystems. This paper discusses our finding that deposition of an ultrathin\ntantalum (Ta) on the NiFe top electrode reversed the nature of\ninter-ferromagnetic electrode coupling. We observed that the deposition of ~ 5\nnm Ta on the top of a magnetic tunnel junction with Ta( 2 nm)/Co(5 nm)/NiFe (5\nnm)/AlOx( 2 nm)/NiFe (10-15 nm) configuration changed the magnetic coupling\nbetween two ferromagnetic electrodes from antiferromagnetic to ferromagnetic.\nWe investigated Ta effect using multiple magnetic characterizations like\nferromagnetic resonance, magnetometry, and polarized neutron reflectometry.\nFerromagnetic resonance characterization was very sensitive for detecting the\nchanges in magnetic coupling via the insulating spacer. This simple approach of\nadding Ta film to alter the magnetic coupling can impact the other burgeoning\nareas like molecular spintronics. We found that preexisting magnetic coupling\nbetween two ferromagnetic electrodes impacted the resultant magnetic properties\nof magnetic tunnel junctions based molecular spintronics devices."
    },
    {
        "anchor": "Effective Dielectric Response of Metamaterials: We use a homogenization procedure for Maxwell's equations in order to obtain\nin the local limit the frequency ($\\omega$) dependent macroscopic dielectric\nresponse $\\epsilon^M(\\omega)$ of metamaterials made of natural constituents\nwith any geometrical shape repeated periodically with any structure. We\nillustrate the formalism calculating $\\epsilon^M(\\omega)$ for several\nstructures. For dielectric rectangular inclusions within a conducting material\nwe obtained a very anisotropic response which changes along one direction from\nconductor-like at low $\\omega$ to a resonant dielectric-like at large $\\omega$,\nattaining a very small reflectance at intermediate frequencies unrelated to\nsurface plasmon excitation and which can be tuned through geometrycal\ntayloring. A similar behavior is obtained for other shapes close to the\npercolation threshold.",
        "positive": "Multiscale modeling of resistive switching in gold nanogranular films: Metallic nanogranular films display a complex dynamical response to a\nconstant bias, showing up as atypical resistive switching mechanism which could\nbe used to create electrical components for neuromorphic applications. To model\nsuch a phenomenon we use a multiscale approach blending together an ab initio\ntreatment of the electric current at the nanoscale, a molecular dynamical\napproach dictating structural rearrangements, and a finite-element solution of\nthe heat equation for heat propagation in the sample. We also consider\nstructural changes due to electromigration which are modelled on the basis of\nexperimental observations on similar systems. Within such an approach, we\nmanage to describe some distinctive features of the resistive switching\noccurring in nanogranular film and provide a physical interpretation at the\nmicroscopic level."
    },
    {
        "anchor": "Bayesian Optimization in Materials Science: A Survey: Bayesian optimization is used in many areas of AI for the optimization of\nblack-box processes and has achieved impressive improvements of the state of\nthe art for a lot of applications. It intelligently explores large and complex\ndesign spaces while minimizing the number of evaluations of the expensive\nunderlying process to be optimized. Materials science considers the problem of\noptimizing materials' properties given a large design space that defines how to\nsynthesize or process them, with evaluations requiring expensive experiments or\nsimulations -- a very similar setting. While Bayesian optimization is also a\npopular approach to tackle such problems, there is almost no overlap between\nthe two communities that are investigating the same concepts. We present a\nsurvey of Bayesian optimization approaches in materials science to increase\ncross-fertilization and avoid duplication of work. We highlight common\nchallenges and opportunities for joint research efforts.",
        "positive": "Investigation of the Electric Field and Charge Density Distribution of\n  pristine and defective 2D WSe$_2$ by Differential Phase Contrast Imaging: Most properties of solid materials are defined by their internal electric\nfield and charge density distributions which so far have been difficult to\nmeasure with sufficient spatial resolution. For 2D materials, the electric\nfield at the atomic level in particular influences the optoelectronic\nproperties. In this study, the atomic-scale electric field and charge density\ndistribution of 2D WSe$_2$ are revealed by using an emerging microscopy\ntechnique, differential phase contrast (DPC) imaging in the scanning\ntransmission electron microscope (STEM). Combined with high-angle annular\ndark-field imaging the charge density distribution of bi- and trilayers of\nWSe$_2$ is mapped. A measured higher positive charge density located at the\nselenium atomic columns compared to the tungsten atomic columns is reported,\nand possible reasons are discussed. Furthermore, the change in the electric\nfield distribution of a selenium point defect in a trilayer is investigated\nexhibiting a characteristic electric field distribution in the vicinity of the\ndefect: there are characteristic regions with locally enhanced and with locally\nreduced electric field magnitudes compared to the pristine lattice."
    },
    {
        "anchor": "Electronic response and bandstructure modulation of carbon nanotubes in\n  a transverse electrical field: The electronic properties of carbon nanotubes in a uniform transverse field\nare investigated within a single orbital tight-binding model. For doped\nnanotubes, the dielectric function is found to depend not only on symmetry of\nthe tube, but also on radius and Fermi level position. Bandgap opening/closing\nis predicted for zigzag tubes, while it is found that armchair tubes always\nremain metallic, which is explained by the symmetry in their configuration. The\nbandstructures for both types are considerably modified when the field strength\nis large enough to mix neighboring subbands.",
        "positive": "Structural relaxation around substitutional Cr3+ in pyrope garnet: The structural environment of substitutional Cr3+ ion in a natural pyrope\nMg3Al2Si3O12 has been investigated by Cr K-edge Extended X-ray Absorption Fine\nStructure (EXAFS) and X-ray Absorption Near Edge Structure (XANES) coupled with\nfirst-principles computations. The Cr-O distance is close to that in\nknorringite Mg3Cr2Si3O12, indicating a full relaxation of the first neighbors.\nThe local C3i symmetry of the octahedral Y site is retained during Cr-Al\nsubstitution. The second and third shells of neighbors (Mg and Si) relax only\npartially. Site relaxation is accommodated by strain-induced bond buckling,\nwith angular tilts of the Si-centered tetrahedra around the Cr-centered\noctahedron, and by a radial deformation of the Mg-centered dodecahedra."
    },
    {
        "anchor": "Vanadium doped beta-Ga2O3 single crystals: Growth, Optical and Terahertz\n  characterization: We report the growth of electrically-resistive vanadium-doped beta-Ga2O3\nsingle crystals via the optical floating zone technique. By carefully\ncontrolling the growth parameters V-doped crystals with very high electrical\nresistivity compared to the usual n-type V-doped beta-Ga2O3 (ne~10^(18)/cm^3)\ncan be synthesized. The optical properties of such high resistive V-doped\nb-Ga2O3 are significantly different compared to the undoped and n-doped\ncrystals. We study the polarization-dependent Raman spectra,\npolarization-dependent transmission, temperature-dependent photoluminescence in\nthe optical wavelength range and the THz transmission properties in the 0.2 -\n2.6 THz range. The V-doped insulating Ga2O3 crystals show strong birefringence\nwith refractive index contrast Dn of 0.3+-0.02 at 1 THz, suggesting it to be an\nideal material for optical applications in the THz region.",
        "positive": "Structural and electronic phase evolution of Tin dioxide: We investigate the effect of controlled annealing on the structural and\nelectronic phase evolution of Tin dioxide from Tin (II) oxyhydroxide prepared\nby simple precipitation method. Thermogravimetric analysis suggests a complex\nweight loss-gain process involved, passing through an intermediate phase of tin\noxide nanoparticles. The probable structural and electronic phase evolution is\ndiscussed using detailed X-ray diffraction and X-ray photoelectron spectroscopy\ninvestigations."
    },
    {
        "anchor": "Correct implementation of polarization constants in wurtzite materials\n  and impact on III-nitrides: Accurate values for polarization discontinuities between pyroelectric\nmaterials are critical for understanding and designing the electronic\nproperties of heterostructures. For wurtzite materials, the zincblende\nstructure has been used in the literature as a reference to determine the\neffective spontaneous polarization constants. We show that, because the\nzincblende structure has a nonzero formal polarization, this method results in\na spurious contribution to the spontaneous polarization differences between\nmaterials. In addition, we address the correct choice of \"improper\" versus\n\"proper\" piezoelectric constants. For the technologically important III-nitride\nmaterials GaN, AlN, and InN, we determine polarization discontinuities using a\nconsistent reference based on the layered hexagonal structure and the correct\nchoice of piezoelectric constants, and discuss the results in light of\navailable experimental data.",
        "positive": "Electronic correlations in short period (CrAs)$_n$/(GaAs)$_n$\n  ferromagnetic heterostructures: We investigate half-metallicity in [001] stacked (CrAs)$_n$/(GaAs)$_n$\nheterostructures with $n \\leq 3$ by means of a combined many-body and\nelectronic structure calculation. Interface states in the presence of strong\nelectronic correlations are discussed for the case $n=1$. For $n=2,3$ our\nresults indicate that the minority spin half-metallic gap is suppressed by\nlocal correlations at finite temperatures, and continuously shrinks upon\nincreasing the heterostructure period. Although around room temperature the\nmagnetization of the heterostructure deviates by only $2%$ from the ideal\ninteger value, finite temperature polarization at $E_F$ is reduced by at least\n$25%$. Below the Fermi level the minority spin highest valence states are found\nto localize more on the GaAs layers while lowest conduction states have a\nmany-body origin. Our results, therefore, suggest that in these\nheterostructures holes and electrons remain separated among different layers."
    },
    {
        "anchor": "Magnetoelectric oscillations in quasi-2D ferrite disk particles: In this paper we show that magnetic-dipolar-mode (MDM) oscillations of a\nquasi-2D ferrite disk are characterized by unique symmetry features with\ntopological phases resulting in appearance of the magnetoelectric (ME)\nproperties. The entire ferrite disk can be characterized as a pair of two,\nelectric and magnetic, coupled eigen moments. However, there is no a \"glued\npair\" of two dipoles. An external electromagnetic field in the near-field\nregion \"views\" such a ME particle, as a system with a normally oriented eigen\nelectric moment and an in-plane rotating eigen magnetic dipole moment.",
        "positive": "Reply to comment on \"Thermal effects -- an alternative mechanism for\n  plasmon-assisted photocatalysis\": Reply to comment on \"Thermal effects -- an alternative mechanism for\nplasmon-assisted photocatalysis\" by P. Jain [Chem. Sci., 2020, 11, DOI:\n10.1039/D0SC02914A]"
    },
    {
        "anchor": "On the propagation of temperature-rate waves and traveling waves in\n  rigid conductors of the Graffi--Franchi--Straughan type: We examine second-sound phenomena in a class of rigid, thermally conducting,\nsolids that are described by a special case of the Maxwell--Catteneo flux law.\nEmploying both analytical and numerical methods, we examine both\ntemperature-rate waves and thermal traveling waves in this class of thermal\nconductor, which have recently been termed Graffi--Franchi--Straughan type\nconductors. In the present study, the temperature-dependent nature of the\nthermal relaxation time, which is the distinguishing feature of this class of\nconductors, gives rise to a variety of nonlinear effects; in particular,\nfinite-time temperature-rate wave blow-up and temperature traveling waveforms\nwhich exhibit a \"tongue\". The presentation concludes with a discussion of\npossible follow-on studies.",
        "positive": "Structural and Magnetic Properties of Er3Fe5-xAlxO12 Garnets: Er3Fe5-xAlxO12 (0.0 < x < 0.8) garnets were prepared by ball milling and\nsintering at 1300 C. Rietveld refinement of the samples revealed a garnet\nstructure with Ia3d symmetry. The lattice parameter, cell volume, X-ray density\nand magnetization of the prepared garnets decreased with the increase of Al\ncontent (x). The coercivity of the garnets increased with x, but remained\ngenerally low, being below 20 Oe. Low temperature magnetic measurements versus\ntemperature indicated that the magnetization of x = 0.0 exhibited a\ncompensation temperature at -186 C, however, x = 0.8 exhibited a minimum at a\nhigher temperature of -134 C."
    },
    {
        "anchor": "On the calculation of the bandgap of periodic solids with MGGA\n  functionals using the total energy: During the last few years, it has become more and more clear that functionals\nof the meta generalized gradient approximation (MGGA) are more accurate than\nGGA functionals for the geometry and energetics of electronic systems. However,\nMGGA functionals are also potentially more interesting for the electronic\nstructure, in particular when the potential is non-multiplicative (i.e., when\nMGGAs are implemented in the generalized Kohn-Sham framework), which may help\nto get more accurate bandgaps. Here, we show that the calculation of bandgap of\nsolids with MGGA functionals can be done very accurately also in a\nnon-self-consistent manner. This scheme uses only the total energy and can,\ntherefore, be very useful when the self-consistent implementation of a\nparticular MGGA functional is not available. Since self-consistent MGGA\ncalculations may be difficult to converge, the non-self-consistent scheme may\nalso help to speed-up the calculations. Furthermore, it can be applied to any\nother types of functionals, for which the implementation of the corresponding\npotential is not trivial.",
        "positive": "Room temperature strain-induced Landau levels in graphene on a\n  wafer-scale platform: Graphene is a powerful playground for studying a plethora of quantum\nphenomena. One of the remarkable properties of graphene arises when it is\nstrained in particular geometries and the electrons behave as if they were\nunder the influence of a magnetic field. Previously, these strain-induced\npseudomagnetic fields have been explored on the nano- and micrometer-scale\nusing scanning probe and transport measurements. Heteroepitaxial strain, in\ncontrast, is a wafer-scale engineering method. Here, we show that\npseudomagnetic fields can be generated in graphene through wafer-scale\nepitaxial growth. Shallow triangular nanoprisms in the SiC substrate generate\nstrain-induced uniform fields of 41 T. This enables the observation of\nstrain-induced Landau levels at room temperature, as detected by angle-resolved\nphotoemission spectroscopy, and confirmed by model calculations and scanning\ntunneling microscopy measurements. Our work demonstrates the feasibility of\nexploiting strain-induced quantum phases in two-dimensional Dirac materials on\na wafer-scale platform, opening the field to new applications."
    },
    {
        "anchor": "Mesoscopic simulations of the in situ NMR spectra of porous carbon based\n  supercapacitors: Electronic structure and adsorbent reorganisation effects: In situ NMR spectroscopy is a powerful technique to investigate charge\nstorage mechanisms in carbon-based supercapacitors thanks to its ability to\ndistinguish ionic and molecular species adsorbed in the porous electrodes from\nthose in the bulk electrolyte. The NMR peak corresponding to the adsorbed\nspecies shows a clear change of chemical shift as the applied potential\ndifference is varied. This variation in chemical shift is thought to originate\nfrom a combination of ion reorganisation in the pores and changes in ring\ncurrent shifts due to the changes of electronic density in the carbon. While\nprevious Density Functional Theory calculations suggested that the electronic\ndensity has a large effect, the relative contributions of these two effects is\nchallenging to untangle. Here, we use mesoscopic simulations to simulate NMR\nspectra and investigate the relative importance of ion reorganisation and ring\ncurrents on the resulting chemical shift. The model is able to predict chemical\nshifts in good agreement with NMR experiments and indicates that the ring\ncurrents are the dominant contribution. A thorough analysis of a specific\nelectrode/electrolyte combination for which detailed NMR experiments have been\nreported allows us to confirm that local ion reorganisation has a very limited\neffect but the relative quantities of ions in pores of different sizes, which\ncan change upon charging/discharging, can lead to a significant effect. Our\nfindings suggest that in situ NMR spectra of supercapacitors may provide\ninsights into the electronic structure of carbon materials in the future.",
        "positive": "2D Single Crystal of High-Temperature Phase Cuprous Iodide under Ambient\n  Conditions: Two-dimensional (2D) materials, with their structural uniqueness, exceptional\nproperties, and wide-ranging applications, show unprecedented prospects in\nfundamental physics research and industrial applications. 2D \\b{eta}-phase\ncuprous iodide (\\b{eta}-CuI) is a promising candidate for overcoming the\nchallenges of insufficient P-type transparent conductive materials, with\nmultiple predicted unique properties. Previous experimental results show that\n\\b{eta}-CuI only occurs at elevated temperatures between 645 and 675 K. Many\nefforts are made to stabilize \\b{eta}-CuI at room temperature through\nsurface/interface engineering. However, the resulting composites limit the\nperformance and application of pure 2D \\b{eta}-CuI. Here, we demonstrate\nexperimentally that isolated 2D \\b{eta}-CuI single crystals can exist stably\nunder ambient conditions, a high-temperature phase CuI found at room\ntemperature. We validate the simultaneous existence of {\\gamma}-CuI and\n\\b{eta}-CuI in the synthesized CuI. The previous neglect of \\b{eta}-CuI\ncrystals can be ascribed to factors including their low content, small\ndimensions, and lack of ingenious experimental characterization. Moreover, the\ntheoretical calculation further confirms dynamically and thermally stable of\nthe monolayer \\b{eta}-CuI, which has an ultra-wide direct band-gap (3.66 eV).\nOur findings challenge the traditional understanding of \\b{eta}-CuI as a\nhigh-temperature phase of CuI, instead providing a new definition that 2D\n\\b{eta}-CuI exhibits remarkable stability under ambient conditions."
    },
    {
        "anchor": "A Practical Introduction to Density Functional Theory: These lecture notes contain a brief practical introduction to doing density\nfunctional theory calculations for crystals using the open source Quantum\nEspresso software. The level is aimed at graduate students who are studying\ncondensed matter or solid state physics, either theoretical or experimental.",
        "positive": "Spectroscopic analysis of vibrational coupling in multi-molecular\n  excited states: Multi-molecular excited states accompanied by an intra- and inter-molecular\ngeometric relaxation are commonly encountered in optical and electrooptical\nstudies and applications of organic semiconductors as, for example excimers or\ncharge transfer states. Understanding the dynamics of these states is crucial\nto improve organic devices such as light emitting diodes and solar cells. Their\nfull microscopic description, however, demands for sophisticated tools such as\nab-initio quantum chemical calculations which come at the expenses of high\ncomputational costs and are prone to errors by assumptions as well as iterative\nalgorithmic procedures. Hence, the analysis of spectroscopic data is often\nconducted on a phenomenological level only. Here, we present a toolkit to\nanalyze temperature dependent luminescence data and gain first insights into\nthe relevant microscopic parameters of the molecular system at hand. By means\nof a Franck-Condon based approach considering a single effective\ninter-molecular vibrational mode and different potentials for the ground and\nexcited state we are able to explain the luminescence spectra of such\nmulti-molecular states. We demonstrate that by applying certain reasonable\nsimplifications the luminescence of charge transfer states as well as excimers\ncan be satisfactorily reproduced for temperatures ranging from cryogenics to\nabove room temperature. We present a semi-classical and a quantum-mechanical\ndescription of our model and, for both cases, demonstrate its applicability by\nanalyzing the temperature depended luminescence of the amorphous donor-acceptor\nheterojunction tetraphenyldibenzoperiflanthene:C$_{60}$ as well as\npolycrystalline zinc-phthalocyanine to reproduce the luminescence spectra and\nextract relevant system parameters such as the excimer binding energy."
    },
    {
        "anchor": "Controlling the density of the 2DEG at the SrTiO3/LaAlO3 interface: The polar discontinuity at the SrTiO3/LaAlO3 interface (STO/LAO) can in\nprinciple sustain an electron density of 3.3E14 cm-2 (0.5 electrons per unit\ncell). However, experimentally observed densities are more than an order of\nmagnitude lower. Using a combination of first-principles and\nSchrodinger-Poisson simulations we show that the problem lies in the asymmetric\nnature of the structure, i.e., the inability to form a second LAO/STO interface\nthat is a mirror image of the first, or to fully passivate the LAO surface. Our\ninsights apply to oxide interfaces in general, explaining for instance why the\nSrTiO3/GdTiO3 interface has been found to exhibit the full density of 3.3E14\ncm-2.",
        "positive": "High resolution determination of ferromagnetic metallic limit in\n  epitaxial La1-xCaxMnO3 films on NdGaO3: The physical properties of manganites depend strongly on sample morphology,\nprobably due to strain. We investigate the influence of NdGaO3 substrates on\nthe limit of the ferromagnetic-metallic phase field in La1-xCaxMnO3, doping\nwith x=1% resolution. Films with x=0.40 show a metal-insulator transition, but\nthe ferromagnetic volume fraction is half the spin aligned value. Films with\nx=0.41 are similar but the metal-insulator transition is not always seen. Films\nwith x=0.42, 0.43, 0.44, 0.45 are insulating, and the magnetization is\ndramatically reduced. The observed phase boundary indicates where to search for\nenhanced phase separation effects that may be exploited in thin films and\ndevices."
    },
    {
        "anchor": "Effects of strain on the valence band structure and exciton-polariton\n  energies in ZnO: The uniaxial stress dependence of the band structure and the\nexciton-polariton transitions in wurtzite ZnO is thoroughly studied using\nmodern first-principles calculations based on the HSE+G0W0 approach, k p\nmodeling using the deformation potential framework, and polarized\nphotoluminescence measurements. The ordering of the valence bands [A(G7),\nB(G9), C(G7)] is found to be robust even for high uniaxial and biaxial strains.\nTheoretical results for the uniaxial pressure coefficients and splitting rates\nof the A, B, and C valence bands and their optical transitions are obtained\nincluding the effects of the spin-orbit interaction. The excitonic deformation\npotentials are derived and the stress rates for hydrostatic pressure are\ndetermined based on the results for uniaxial and biaxial stress. In addition,\nthe theory for the stress dependence of the exchange interaction and\nlongitudinal-transversal splitting of the exciton-polaritons is developed using\nthe basic exciton functions of the quasi-cubic approximation and taking the\ninteraction between all exciton states into account. It is shown that the\nconsideration of these effects is crucial for an accurate description of the\nstress dependence of the optical spectra in ZnO. The theoretical results are\ncompared to polarized photoluminescence measurements of different ZnO\nsubstrates as function of uniaxial pressure and experimental values reported in\nthe literature demonstrating an excellent agreement with the computed pressure\ncoefficients.",
        "positive": "Two-dimensional Kagome-in-Honeycomb materials (MN$_4$)$_3$C$_{32}$ (M=Pt\n  or Mn): We propose two novel two-dimensional (2D) topological materials,\n(PtN$_4$)$_3$C$_{32}$ and (MnN$_4$)$_3$C$_{32}$, with a special geometry that\nwe named as kagome-in-honeycomb (KIH) lattice structure, to illustrate the\ncoexistence of the paradigmatic states of kagome physics, Dirac fermions and\nflat bands, that are difficult to be simultaneously observed in\nthree-dimensional realistic systems. In such system, MN$_4$(M=Pt or Mn)\nmoieties are embedded in honeycomb graphene sheet according to kagome lattice\nstructure, thereby resulting in a KIH lattice. Using the first-principles\ncalculations, we have systemically studied the structural, electronic, and\ntopological properties of these two materials. In the absence of spin-orbit\ncoupling (SOC), they both exhibit the coexistence of Dirac/quadratic-crossing\ncone and flat band near the Fermi level. When SOC is included, a sizable\ntopological gap is opened at the Dirac/quadratic-crossing nodal point. For\nnonmagnetic (PtN$_4$)$_3$C$_{32}$, the system is converted into a\n$\\mathbb{Z}_2$ topological quantum spin Hall insulator defined on a curved\nFermi level, while for ferromagnetic (MnN$_4$)$_3$C$_{32}$, the material is\nchanged from a half-semi-metal to a quantum anomalous Hall insulator with\nnonzero Chern number and nontrivial chiral edge states. Our findings not only\npredict a new family of 2D quantum materials, but also provide an\nexperimentally feasible platform to explore the emergent kagome physics,\ntopological quantum Hall physics, strongly correlated phenomena, and theirs\nfascinating applications."
    },
    {
        "anchor": "Ternary Alkali Metal Copper Chalcogenides ACuX (A= Na, K and X= S, Se,\n  Te): Promising Candidate for Solar Harvesting Applications: We report a comprehensive first-principles study of the relative stability of\nthe various possible crystal structures, and the electronic and optical\nproperties of ternary alkali metal chalcogenides ACuX (A= Na/K and X= S/Se/Te)\ncompounds through density functional theory (DFT) calculations. The energetics\nand phonon spectra of greater than 700 structures were compared, and seven\npossible stabilized structures of six ACuX compounds were identified using the\nfixed composition evolutionary search method. Our electronic band structure\nsimulation confirms that all the ternary ACuX compounds are direct band gap\nsemiconductors, with the band gap lying between 0.83 eV to 2.88 eV. These\ncompounds exhibit directly allowed electronic transitions from the valence band\nto the conduction band, which leads to a significant strength of optical\ntransition probability. This yields a sharp rise in the optical absorption\nspectra (ranging between 10$^4$ to 10$^5$ cm$^{-1}$) near the energy gap. The\nestimated spectroscopic limited maximum efficiency (SLME) is about 18% for an 8\n$\\mu$m thick NaCuTe film. For other ACuX compounds, the SLME ranges between 10%\nto 13%. In addition, we also explored the feasibility of these ternary ACuX\ncompounds for photocatalytic water splitting applications and found that they\ncan be promising candidates as photocathodes for hydrogen evolution reactions.\nWith a large spread in the band gap and interesting band topology near Fermi\nlevel, these chalcogenides can be quite fertile for other energy applications\nsuch as thermoelectric, LED, etc.",
        "positive": "A- and B-Exciton Photoluminescence Intensity Ratio as a Measure of\n  Sample Quality for Transition Metal Dichalcogenide Monolayers: The photoluminescence (PL) in monolayer transition metal dichalcogenides\n(TMDs) is dominated by recombination of electrons in the conduction band with\nholes in the spin-orbit split valence bands, and there are two distinct\nemission features referred to as the A-peak (ground state exciton) and B-peak\n(higher spin-orbit split state). The intensity ratio of these two features\nvaries widely and several contradictory interpretations have been reported. We\nanalyze the room temperature PL from MoS2, MoSe2, WS2, and WSe2 monolayers and\nshow that these variations arise from differences in the non-radiative\nrecombination associated with defect densities. Hence, the relative intensities\nof the A- and B-emission features can be used to qualitatively asses the\nnon-radiative recombination, and thus the quality of the sample. A low B/A\nratio is indicative of low defect density and high sample quality. Emission\nfrom TMD monolayers is governed by unique optical selection rules which make\nthem promising materials for valleytronic operations. We observe a notably\nhigher valley polarization in the B-exciton relative to the A-exciton. The high\npolarization is a consequence of the shorter B-exciton lifetime resulting from\nrapid relaxation of excitons from the B-exciton to the A-exciton of the valence\nband."
    },
    {
        "anchor": "Direct coupling of first-principles calculations with replica exchange\n  Monte Carlo sampling of ion disorder in solids: We demonstrate the feasibility of performing sufficient configurational\nsampling of disordered oxides directly from first principles without resorting\nto the use of fitted models such as cluster expansion. This is achieved by\nharnessing the power of modern-day cluster supercomputers using the replica\nexchange Monte Carlo method coupled directly with structural relaxation and\nenergy calculation performed by density functional codes. The idea is applied\nsuccessfully to the calculation of the temperature-dependence of the degree of\ninversion in the cation sublattice of MgAl$_2$O$_4$ spinel oxide. The\npossibility of bypassing fitting models will lead to investigation of\ndisordered systems where cluster expansion is known to perform badly: for\nexample, systems with large lattice deformation due to defects, or systems\nwhere long-range interactions dominate such as electrochemical interfaces.",
        "positive": "A stable and low loss oxide for superconducting qubits: The dielectric loss of amorphous oxide layers is a major limiting factor for\nthe coherent time of superconducting qubits. Usually, the surface oxides of\nsuperconductor film are lossy and unstable in air. To increase the coherence\ntime, it is essential for qubits to have stable and low dielectric loss oxides,\neither as barrier or passivation layers. Here, we demonstrate that a kind of\namorphous tantalum oxide on Ta film is robust and stable by means of chemical\nand structural analysis. Such kind of oxide layer forms in a self-limiting\nprocess on the surface of {\\alpha}-Ta (110) film in piranha solution, yielding\nstable thickness and steady chemical composition. Quarter-wavelength coplanar\nwaveguide resonators are made to study the loss of this oxide. An internal\nquality factor of above three million is measured at single photon level for\nfresh device, and it is still over two million even after exposed to air for\nmonths. Furthermore, we propose a method to fabricate all-tantalum\nsuperconducting qubits using this kind of oxide as the dielectric and\npassivation layers."
    },
    {
        "anchor": "Critical enhancement of the spin Hall effect by spin fluctuations: The spin Hall (SH) effect, the conversion of the electric current to the spin\ncurrent along the transverse direction, relies on the relativistic spin-orbit\ncoupling (SOC). Here, we develop a microscopic theory on the mechanisms of the\nSH effect in magnetic metals, where itinerant electrons are coupled with\nlocalized magnetic moments via the Hund exchange interaction and the SOC. Both\nantiferromagnetic metals and ferromagnetic metals are considered. It is shown\nthat the SH conductivity can be significantly enhanced by the spin fluctuation\nwhen approaching the magnetic transition temperature of both cases. For\nantiferromagnetic metals, the pure SH effect appears in the entire temperature\nrange, while for ferromagnetic metals, the pure SH effect is expected to be\nreplaced by the anomalous Hall effect below the transition temperature. We\ndiscuss possible experimental realizations and the effect of the quantum\ncriticality when the antiferromagnetic transition temperature is tuned to zero\ntemperature.",
        "positive": "Giant Thermal Enhancement of the Electric Polarization in Ferrimagnetic\n  BiFe$_{1-x}$Co$_{x}$O$_{3}$ Solid Solutions Near Room Temperature: Thermal excitations typically reduce the electric polarization in\nferroelectric materials. Here, we show by means of first-principles\ncalculations that multiferroic BiFe$_{1-x}$Co$_{x}$O$_{3}$ solid solutions with\n$0.25 \\le x \\le 0.50$ (BFCO) represent a noteworthy exception to this\nbehaviour. In particular, we find that at room temperature and for moderate\npressures of $0.1$-$1.0$ GPa, depending on the composition, the electric\npolarization of bulk BFCO increases by $\\sim 200$%. The origin of such an\nexceptional behavior is a phase transformation involving a low-$T$ rhombohedral\n(${\\cal R}$) phase and a high-$T$ super-tetragonal (${\\cal T}$) phase. Both\n${\\cal R}$ and ${\\cal T}$ phases are ferrimagnetic near room temperature with\nan approximate net magnetization of $0.13$$\\mu_{B}$ per formula unit.\nContrarily to what occurs in either bulk BiFeO$_{3}$ or BiCoO$_{3}$, the ${\\cal\nT}$ phase is stabilized over the ${\\cal R}$ by increasing temperature due to\nits higher vibrational entropy. This extraordinary $T$-induced ${\\cal R} \\to\n{\\cal T}$ phase transition is originated by polar phonon modes involving\nconcerted displacements of transition-metal and oxygen ions."
    },
    {
        "anchor": "Fracture behavior of MOF monoliths revealed by nanoindentation and\n  nanoscratch: Monolithic metal-organic frameworks (MOFs) represent a promising solution for\nthe industrial implementation of this emerging class of multifunctional\nmaterials, due to their structural stability. When compared to MOF powders,\nmonoliths exhibit other intriguing properties like hierarchical porosity, that\nsignificantly improves volumetric adsorption capacity. The mechanical\ncharacterization of MOF monoliths plays a pivotal role in their industrial\nexpansion, but so far, several key aspects remain unclear. In particular, the\nfracture behavior of MOF monoliths has not been explored. In this work, we\nstudied the initiation and propagation of cracks in four prototypical MOF\nmonoliths, namely ZIF-8, HKUST-1, MIL-68 and MOF-808. We observed that shear\nfaults inside the contact area represent the main failure mechanism of MOF\nmonoliths and are the source of radial cracks. MIL-68 and MOF-808 showed a\nremarkably high resistance to cracking, which can be ascribed to their\nconsolidated nanostructure.",
        "positive": "Chemical characterization of dislocation in yttria-stabilized zirconia: This study demonstrates that a space charge layer is formed on dislocation\nduring mechanical deformation at elevated temperature. High density of\ndislocation lines is generated in bulk single crystalline Y2O3 stabilized ZrO2\n(YSZ) by uniaxial compression at elevated temperature. The creation of\ndislocation is proven with transmission electron microscopy (TEM). Then,\nenergy-dispersive X-ray spectroscopy (EDS) and electron energy loss\nspectroscopy (EELS) are used to explore the changes in the composition on and\naway from the dislocation lines. Also, it is clarified that segregation of\ndopant atoms (yttrium) on the dislocation line is induced by high temperature\nannealing. Comparing the compositional variations with and without thermal\nannealing, we study the space charge layer formed on dislocation lines in a\ndoped system."
    },
    {
        "anchor": "Maximally-localized Wannier functions for entangled energy bands: We present a method for obtaining well-localized Wannier-like functions (WFs)\nfor energy bands that are attached to or mixed with other bands. The present\nscheme removes the limitation of the usual maximally-localized WFs method (N.\nMarzari and D. Vanderbilt, Phys. Rev. B 56, 12847 (1997)) that the bands of\ninterest should form an isolated group, separated by gaps from higher and lower\nbands everywhere in the Brillouin zone. An energy window encompassing N bands\nof interest is specified by the user, and the algorithm then proceeds to\ndisentangle these from the remaining bands inside the window by filtering out\nan optimally connected N-dimensional subspace. This is achieved by minimizing a\nfunctional that measures the subspace dispersion across the Brillouin zone. The\nmaximally-localized WFs for the optimal subspace are then obtained via the\nalgorithm of Marzari and Vanderbilt. The method, which functions as a\npostprocessing step using the output of conventional electronic-structure\ncodes, is applied to the s and d bands of copper, and to the valence and\nlow-lying conduction bands of silicon. For the low-lying nearly-free-electron\nbands of copper we find WFs which are centered at the tetrahedral interstitial\nsites, suggesting an alternative tight-binding parametrization.",
        "positive": "Enhancement of Coherent Phonon Amplitude in Phase-change Materials by\n  Near-infrared Laser Irradiation: We have examined the effect of pump-probe photon energy on the amplitude of\ncoherent optical phonons in a prototypical phase change material using a\nfemtosecond time-resolved transmission technique. The photon energy was varied\nbetween 0.8 and 1.0 eV (corresponding to the wavelength of 1550 and 1200 nm), a\nrange over which there is significant optical contrast between the crystalline\nand amorphous phases of Ge$_{2}$Sb$_{2}$Te$_{5}$ (GST225). It was found that in\ncrystalline GST225 the coherent phonon amplitude monotonically increases as the\nphoton energy increases, indicating that the phonon amplitude is enhanced by\ninterband optical absorption, which is associated with the imaginary part of\nthe dielectric function. In amorphous GST225, in contrast, the coherent phonon\namplitude does not depend on the photon energy, remaining almost constant over\nthe tuning range. A possible contribution from the polarizability associated\nwith resonant bonding nature of GST225 is discussed."
    },
    {
        "anchor": "Anisotropic dielectric functions, band-to-band transitions, and critical\n  points in \u03b1-Ga2O3: We use a combined generalized spectroscopic ellipsometry and density\nfunctional theory approach to determine and analyze the anisotropic dielectric\nfunctions of an $\\alpha$-Ga$_2$O$_3$ thin film. The sample is grown epitaxially\nby plasma-assisted molecular beam epitaxy on $m$-plane sapphire. Generalized\nspectroscopic ellipsometry data from multiple sample azimuths in the spectral\nrange from 0.73 eV to 8.75 eV are simultaneously analyzed. Density functional\ntheory is used to calculate the valence and conduction band structure. We\nidentify, for the indirect-bandgap material, two direct band-to-band\ntransitions with $M_0$-type van Hove singularities for polarization\nperpendicular to the $c$ axis, $E_{0,\\perp}=5.46(6)$ eV and\n$E_{0,\\perp}=6.04(1)$ eV, and one direct band-to-band transition with\n$M_1$-type van Hove singularity for polarization parallel with\n$E_{0,||}=5.44(2)$ eV. We further identify excitonic contributions with small\nbinding energy of 7 meV associated with the lowest ordinary transition, and a\nhyperbolic exciton at the $M_1$-type critical point with large binding energy\nof 178 meV.",
        "positive": "Structural instability of EuTiO3 from X-ray powder diffraction: We have recently predicted and subsequently verified experimentally by\nspecific heat measurements that EuTiO3 undergoes a structural phase transition\nat elevated temperature TS = 282 K. The origin of the phase transition has been\nattributed to the softening of a transverse acoustic mode stemming from an\noxygen octahedral rotation analogous to SrTiO3. Here we demonstrate that the\ntheoretical interpretation is correct by using high resolution laboratory X-ray\npowder diffraction which evidences a cubic to tetragonal phase transition in\nEuTiO3. The room temperature structure could be refined in with a = 3.9082(2)\n{\\AA} and at 100 K the refinement in the tetragonal space group resulted in a =\n5.5192(2) and c = 7.8164(8) {\\AA}."
    },
    {
        "anchor": "Spin wave spectra of single crystal CoPS$_3$: The spin waves in single crystals of the layered van der Waals\nantiferromagnet CoPS$_3$ have been measured using inelastic neutron scattering.\nThe data show four distinct spin wave branches with large ($\\gtrsim 14$ meV)\nenergy gaps at the Brillouin zone center indicating significant anisotropy. The\ndata were modelled using linear spin wave theory derived from a Heisenberg\nHamiltonian. Exchange interactions up to the third nearest-neighbour in the\nlayered planes were required to fit the data with ferromagnetic $J_1 = -1.37$\nmeV between first neighbours, antiferromagnetic $J_3 = 3.0$ meV between third\nneighbours, and a very small $J_2 = 0.09$ meV between second neighbours. A\nbiaxial single-ion anisotropy was required, with a collinear term $D^x = -0.77$\nmeV for the axis parallel to the aligned moment direction and a coplanar term\n$D^z=6.07$ meV for an axis approximately normal to the layered crystal planes.",
        "positive": "Local Manipulation of Skyrmion Lattice in Fe3GaTe2 at Room Temperature: Motivated by advances in spintronic devices, an extensive exploration is\nunderway to uncover materials that host topologically protected spin textures,\nexemplified by skyrmions. One critical challenge involved in the potential\napplication of skyrmions in van der Waals (vdW) materials is the attainment and\nmanipulation of skyrmions at room temperature. In this study, we report the\ncreation of intrinsic skyrmion state in van der Waals ferromagnet Fe3GaTe2. By\nemploying variable temperature magnetic force microscopy, the skyrmion lattice\ncan be locally manipulated on Fe3GaTe2 flake. The ordering of skyrmion state is\nfurther analyzed. Our result suggest Fe3GaTe2 emerges as a highly promising\ncontender for the realization of skyrmion-based layered spintronic memory\ndevices."
    },
    {
        "anchor": "Assessing the efficiency of first-principles basin-hopping sampling: We present a systematic performance analysis of first-principles\nbasin-hopping (BH) runs, with the target to identify all low-energy isomers of\nsmall Si and Cu clusters described within density-functional theory. As\nrepresentative and widely employed move classes we focus on single-particle and\ncollective moves, in which one or all atoms in the cluster at once are\ndisplaced in a random direction by some prescribed move distance, respectively.\nThe analysis provides detailed insights into the bottlenecks and governing\nfactors for the sampling efficiency, as well as simple rules-of-thumb for\nnear-optimum move settings, that are intriguingly independent of the distinctly\ndifferent chemistry of Si and Cu. At corresponding settings, the observed\nperformance of the BH algorithm employing two simple, general-purpose move\nclasses is already very good, and for the small systems studied essentially\nlimited by frequent revisits to a few dominant isomers.",
        "positive": "Topological Insulators: An in-depth Review of their Use in Modelocked\n  Fiber Lasers: Topological Insulators (TIs) exhibit exciting optical properties, which opens\nup a new pathway to generate ultrashort pulses from fiber lasers. Layered TIs\ndisplay distinct saturable absorption property due to excited state absorption,\nas compared to their bulk structures. Moreover, the electronic structures of\nthe films of TIs depend on the thickness of the films due to the quantum\nconfinement of the electrons. By virtue of this, the nanoparticles of TIs play\na key role in all-fiber modelocked laser. By tweaking the crystal structures of\nTIs, it is possible to generate ultrashort pulses across the visible,\nnear-infrared and mid-infrared wavelengths. Starting from the crystal\nstructures and density of states calculations, how different topological\ninsulators can be fabricated and integrated as an efficient passive saturable\nabsorber in all-fiber modelocked lasers with the capability of producing\nfundamental to high-harmonic pulse generation are described clearly in this\nreview report. Moreover, this report reviews the current state-of-art of\nTI-based saturable absorbers and their applications in different regimes of\nmodelocked fiber lasers."
    },
    {
        "anchor": "Direct correlation between aromatization of carbon- rich organic matter\n  and its visible electronic absorption edge: The evolution of the electronic absorption edge of type I, II and III kerogen\nis studied by diffuse reflectance UV-Visible absorption spectroscopy. The\nfunctional form of the electronic absorption edge for all kerogens measured is\nin excellent agreement with the \"Urbach tail\" phenomenology. The Urbach decay\nwidth extracted from the exponential fit within the visible range is strongly\ncorrelated with the aliphatic/aromatic ratio in isolated kerogen, regardless of\nthe kerogen type. No correlation is found between the decay width and the\naverage size of aromatic clusters, which is explained in terms of a non-linear\nincrease in optical absorption with increasing size of the aromatic clusters\ndetermined by 13C NMR. Further, absorption spectra calculated with density\nfunctional theory calculations on proxy ensemble models of kerogen are in\nexcellent agreement with the experimental results. The correlation of the decay\nwidth with conventional maturity indicators such as vitrinite reflectance is\nfound to be good within a particular kerogen type, but not consistent across\ndifferent kerogen types, reflecting systematic variations in bulk composition\nfor different type kerogen types with the same vitrinite reflectance. Thus,\ndiffuse reflectance visible absorption spectroscopy is presented as a rapid,\ncalibrated and non-destructive method to monitor both the maturity and the\nchemical composition of kerogen. The chemical insight of kerogen in relation to\nits optical absorption provided by this methodology may serve for rapid\nscreening of kerogen for electronics and optical devices in place of\nfunctionalized produced carbon.",
        "positive": "Manipulating domain wall chirality by current pulses in Permalloy/Ir\n  nanostrips: Using magnetic force microscopy and micromagnetic simulations, we studied the\neffect of Oersted magnetic fields on the chirality of transverse magnetic\ndomain walls in Fe$_{20}$Ni$_{80}$/Ir bilayer nanostrips. Applying nanosecond\ncurrent pulses with a current density of around $2\\times10^{12}$ A/m$^2$, the\nchirality of a transverse domain wall could be switched reversibly and\nreproducibly. These current densities are similar to the ones used for\ncurrent-induced domain wall motion, indicating that the Oersted field may\nstabilize the transverse wall chirality during current pulses and prevent\ndomain wall transformations."
    },
    {
        "anchor": "Micromechanics-Based Simulations of Compressive and Tensile Testing on\n  Lime-Based Mortars: The purpose of this paper is to propose a continuum micromechanics model for\nthe simulation of uniaxial compressive and tensile tests on lime-based mortars,\nin order to predict their stiffness, compressive and tensile strengths, and\ntensile fracture energy. In tension, we adopt an incremental strain-controlled\nform of the Mori-Tanaka scheme with a damageable matrix phase, while a simple\n$J_2$ yield criterion is employed in compression. To reproduce the behavior of\nlime-based mortars correctly, the scheme must take into account shrinkage\ncracking among aggregates. This phenomenon is introduced into the model via\npenny-shaped cracks, whose density is estimated on the basis of a particle size\ndistribution combined with the results of finite element analyses of a single\ncrack formation between two spherical inclusions. Our predictions show a good\nagreement with experimental data and explain the advantages of compliant\ncrushed brick fragments, often encountered in ancient mortars, over stiff sand\nparticles. The validated model provides a reliable tool for optimizing the\ncomposition of modern lime-based mortars with applications in conservation and\nrestoration of architectural heritage.",
        "positive": "Reversal of current blockade through multiple trap correlations: Current noise in electronic devices usually arises from uncorrelated charging\nevents, with individual transitions resolved only at low temperatures. However,\nin 1-D nanotube-based transistors, we have observed random telegraph signal\n(RTS) with unprecedented signal-to-noise ratio at room temperature. In\naddition, we find evidence for cooperative multi-trap interactions that give\nrise to a characteristically terminated RTS: current blockade induced by one\ntrap is found to fully reverse through electrostatic `passivation' by another.\nOur observations are well described by a robust quantum transport model that\ndemonstrates how strong correlation and fast varying potentials can resolve\nenergetically proximal states along a 1-D channel."
    },
    {
        "anchor": "Hierarchical colloidal nanostructures - from fundamentals to\n  applications: Editorial for the Special Issue of \"Zeitschrift fuer Physikalische Chemie\" on\n\"Hierarchical Colloidal Nanostructures\"",
        "positive": "Coarse Grained Density Functional Theories for Metallic Alloys:\n  Generalized Coherent Potential Approximations and Charge Excess Functional\n  Theory: The class of the Generalized Coherent Potential Approximations (GCPA) to the\nDensity Functional Theory (DFT) is introduced within the Multiple Scattering\nTheory formalism for dealing with, ordered or disordered, metallic alloys. All\nGCPA theories are based on a common ansatz for the kinetic part of the\nHohenberg-Kohn functional and each theory of the class is specified by an\nexternal model concerning the potential reconstruction. The GCPA density\nfunctional consists of marginally coupled local contributions, does not depend\non the details of the charge density and can be exactly rewritten as a function\nof the appropriate charge multipole moments associated with each lattice site.\nA general procedure based on the integration of the 'qV' laws is described that\nallows for the explicit construction the same function. The coarse grained\nnature of the GCPA density functional implies great computational advantages\nand is connected with the O(N) scalability of GCPA algorithms. Moreover, it is\nshown that a convenient truncated series expansion of the GCPA functional leads\nto the Charge Excess Functional (CEF) theory [E. Bruno, L. Zingales and Y.\nWang, Phys. Rev. Lett. {\\bf 91}, 166401 (2003)] which here is offered in a\ngeneralized version that includes multipolar interactions. CEF and the GCPA\nnumerical results are compared with status of art LAPW full-potential density\nfunctional calculations for 62, bcc- and fcc-based, ordered CuZn alloys, in all\nthe range of concentrations. These extensive tests show that the discrepancies\nbetween GCPA and CEF are always within the numerical accuracy of the\ncalculations, both for the site charges and the total energies. Furthermore,\nGCPA and CEF very carefully reproduce the LAPW site charges and the total\nenergy trends."
    },
    {
        "anchor": "Quantum Anomalous Hall Effect in Antiferromagnetism: So far, experimentally realized quantum anomalous Hall (QAH) insulators all\nexhibit ferromagnetic order and the QAH effect only occurs at very low\ntemperatures. On the other hand, up to now the QAH effect in antiferromagnetic\n(AFM) materials has never been reported. In this letter, we realize the QAH\neffect by proposing a four-band lattice model with static AFM order, which\nindicates that the QAH effect can be found in AFM materials. Then, as a\nprototype, we demonstrate that a monolayer CrO can be switched from an AFM Weyl\nsemimetal to an AFM QAH insulator by applying strain, based on symmetry\nanalysis and the first-principles electronic structure calculations. Our work\nnot only proposes a new scenario to search for QAH insulators in materials, but\nalso reveals a way to considerably increase the critical temperature of the QAH\nphase.",
        "positive": "Observation of extremely long exciton lifetime in Janus-MoSTe monolayer: The electron-hole separation efficiency is a key factor that determines the\nperformance of two-dimensional (2D) transition metal dichalcogenides (TMDs) and\ndevices. Therefore, searching for novel 2D TMD materials with long timescale of\ncarrier lifetime becomes one of the most important topics. Here, based on the\ntimedomain density functional theory (TD-DFT), we propose a brand new TMD\nmaterial, namely janus-MoSTe, which exhibits a strong build-in electric field.\nOur results show that in janus-MoSTe monolayer, the exciton consisting of\nelectron and hole has a relatively wide spatial extension and low binding\nenergy. In addition, a slow electron-hole recombination process is observed,\nwith timescale on the order of 1.31 ns, which is even comparable with those of\nvan der Waals (vdW) heterostructures. Further analysis reveals that the\nextremely long timescale for electron-hole recombination could be ascribed to\nthe strong Coulomb screening effect as well as the small overlap of\nwavefunctions between electrons and holes. Our findings establish the build-in\nelectric field as an effective factor to control the electron-hole\nrecombination dynamics in TMD monolayers and facilitate their future\napplications in light detecting and harvesting."
    },
    {
        "anchor": "Remarkable enhancement in catechol sensing by the decoration of\n  selective transition metals in biphenylene sheet: A systematic\n  first-principles study: Motivated by the recent successful synthesis of biphenylene structure\n[Science 372, (2021), 852], we have explored the sensing properties of this\nmaterial towards the catechol biomolecule by performing the first-principles\ndensity functional theory and molecular dynamics simulations. Pristine\nbiphenylene sheet adsorbs catechol molecule with a binding energy of -0.35 eV,\nwhich can be systematically improved by decorating the transition metals (Ag,\nAu, Pd, and Ti) at various possible sites of biphenylene. It is observed that\nthe catechol molecule is adsorbed on Pd and Ti-decorated biphenylene sheets\nwith strong adsorption energies of -1.00 eV and -2.54 eV, respectively. The\ninteraction of the catechol molecule with biphenylene and metal-decorated\nbiphenylene is due to the charge transfer from the O-2p orbitals of the\ncatechol molecule to the C-2p orbitals of biphenylene and d-orbitals of metals\nin metal-decorated biphenylene, respectively. From the Bader charge\ncalculation, we found that 0.05e amount of charge is transferred from the\ncatechol molecule to pristine biphenylene, which gets almost double (~0.1e) for\nthe Ti-decorated biphenylene sheet. The diffusion energy barrier for the\nclustering of the Pd and Ti atoms comes out to be 2.39 eV and 4.29 eV, computed\nby performing the climbing-image nudged elastic band calculations. We found\nthat the catechol molecule gets desorbed from the pristine biphenylene sheet\neven at 100 K but remains attached to metal (Pd, Ti) decorated biphenylene\nsheets at room temperature by performing the ab-initio molecular dynamics\nsimulations. The Ti-decorated biphenylene sheet has more sensitivity toward\ncatechol adsorption while the Pd-decorated biphenylene sheet has a suitable\nrecovery time at 500 K. The results suggest that the Pd and Ti-decorated\nbiphenylene sheets are promising materials for catechol detection.",
        "positive": "Crystal growth and electronic properties of a 3D Rashba material, BiTeI,\n  with adjusted carrier concentrations: 3D Rashba materials can be a leading player in spin-related novel phenomena,\nranging from the metallic extreme (unconventional superconductivity) to the\ntransport intermediate (spin Hall effects) to the novel insulating variant (3D\ntopological insulating states). As the essential backbone for both fundamental\nand applied research of such a 3D Rashba material, this study established the\ngrowth of sizeable single crystals of a candidate compound BiTeI with adjusted\ncarrier concentrations. Three techniques (standard vertical Bridgman, modified\nhorizontal Bridgman, and vapour transport) were employed, and BiTeI crystals (>\n1 * 1 * 0.2 mm3) with fundamentally different electronic states from metallic\nto insulating were successfully grown by the chosen techniques. The 3D Rashba\nelectronic states, including the Fermi surface topology, for the corresponding\ncarrier concentrations of the obtained BiTeI crystals were revealed by\nrelativistic first-principles calculations."
    },
    {
        "anchor": "A Nexafs Study of Nitric Oxide Layers Adsorbed from a nitrite Solution\n  onto a Pt(111) Surface: NO molecules adsorbed on a Pt(111) surface from dipping in an acidic nitrite\nsolution are studied by near edge X-ray absorption fine structure spectroscopy\n(NEXAFS), X-ray photoelectron spectroscopy (XPS), low energy electron\ndiffraction (LEED) and scanning tunnelling microscopy (STM) techniques. LEED\npatterns and STM images show that no long range ordered structures are formed\nafter NO adsorption on a Pt(111) surface. Although the total NO coverage is\nvery low, spectroscopic features in N K-edge and O K-edge absorption spectra\nhave been singled out and related to the different species induced by this\npreparation method. From these measurements it is concluded that the NO\nmolecule is adsorbed trough the N atom in an upright conformation. The maximum\nsaturation coverage is about 0.3 monolayers, and although nitric oxide is the\nmajor component, nitrite and nitrogen species are slightly co-adsorbed on the\nsurface. The results obtained from this study are compared with those\npreviously reported in the literature for NO adsorbed on Pt(111) under UHV\nconditions.",
        "positive": "Coupling of microwave magnetic dynamics in thin ferromagnetic films to\n  stripline transducers in the geometry of the broadband stripline\n  ferromagnetic resonance: We constructed a quasi-analytical self-consistent model of the\nstripline-based broadband ferromagnetic resonance (FMR) measurements of\nferromagnetic films. Exchange-free description of magnetization dynamics in the\nfilms allowed us to obtain simple analytical expressions. They enable quick and\nefficient numerical simulations of the dynamics. With this model we studied the\ncontribution of radiation losses to the ferromagnetic resonance linewidth, as\nmeasured with the stripline FMR. We found that for films with large\nconductivity of metals the radiation losses are significantly smaller than for\nmagneto-insulating films. Excitation of microwave eddy currents in these\nmaterials contributes to the total microwave impedance of the system. This\nleads to impedance mismatch with the film environment resulting in decoupling\nof the film from the environment and, ultimately, to smaller radiation losses.\nWe also show that the radiation losses drop with an increase in the stripline\nwidth and when the sample is lifted up from the stripline surface. Hence, in\norder to eliminate this measurement artifact one needs to use wide striplines\nand introduce a spacer between the film and the sample surface. The radiation\nlosses contribution is larger for thicker films."
    },
    {
        "anchor": "Na-ion Dynamics in the Solid Solution Na$_{\\rm x}$Ca$_{1- \\rm\n  x}$Cr$_2$O$_4$ Studied by Muon Spin Rotation and Neutron Diffraction: In this work we present systematic set of measurements carried out by muon\nspin rotation/relaxation ($\\mu^+$SR) and neutron powder diffraction (NPD) on\nthe solid solution Na$_{\\rm x}$Ca$_{1- \\rm x}$Cr$_2$O$_4$. This study\ninvestigates Na-ion dynamics in the quasi-1D (Q1D) diffusion channels created\nby the honeycomb-like arrangement of CrO$_6$ octahedra, in the presence of\ndefects introduced by Ca doping. With increasing Ca content, the size of the\ndiffusion channels is enlarged, however, this effect does not enhance the Na\nion mobility. Instead the overall diffusivity is hampered by the local defects\nand the Na hopping probability is lowered. The diffusion mechanism in Na$_{\\rm\nx}$Ca$_{1- \\rm x}$Cr$_2$O$_4$ was found to be interstitial and the activation\nenergy as well as diffusion coefficient were determined for all the members of\nthe solid solution.",
        "positive": "Hydrogen plasma exposure of In/ITO bilayers as an effective way for\n  dispersing In nanoparticles: We address the production of indium nanoparticles (In NPs) from In thin films\nthermally evaporated on both c-Si substrates and sputtered indium tin oxide\n(ITO) as well as from sputtered ITO thin films, exposed to a hydrogen (H2)\nplasma. On the one hand, we show that evaporated In thin films grow in\nVolmer-Weber (VW) mode; H2 plasma reduces their surface oxide and substrate\nannealing reshapes them from flat islands into spheres, without any remarkable\nsurface migration or coalescence. On the other hand, we studied the In NPs\nformation on the ITO thin films and on In/ITO bilayer structures, by varying\nthe H2 plasma exposure time and the substrate temperature. This led us to\npostulate that the main role of H2 plasma is to release In atoms from ITO\nsurface. At low substrate temperature (100{\\deg}C), In NPs grow on ITO surface\nvia a solid phase VW mode, similar to evaporated In thin films, while at\n300{\\deg}C, small In droplets preferentially nucleate along the ITO grain\nboundaries where ITO reduction rate and atomic diffusion coefficient are higher\ncompared with the ITO grain surface. As the droplets grow larger and connect\nwith each other, larger ones (1-2 um microns) are suddenly formed based on a\nliquid phase growth-connection-coalescence process. This phenomenon is even\nstronger in the case of In/ITO bilayer where the large In drops resulting from\nthe evaporated In connect with the smaller NPs resulting from ITO reduction and\nrapidly merge into very large NPs (15 um)"
    },
    {
        "anchor": "TiO2 as an electrostatic template for epitaxial growth of EuO on\n  MgO(001) by reactive molecular beam epitaxy: We investigate the initial growth modes and the role of interfacial\nelectrostatic interactions of EuO epitaxy on MgO(001) by reactive molecular\nbeam epitaxy. A TiO2 interfacial layer is employed to produce high quality\nepitaxial growth of EuO on MgO(001) with a 45{\\deg} in plane rotation. For\ncomparison, direct deposition of EuO on MgO, without the TiO2 layer shows a\nmuch slower time evolution in producing a single crystal film. Conceptual\narguments of electrostatic repulsion of like-ions are introduced to explain the\nincreased EuO quality at the interface with the TiO2 layer. It is shown that\nultrathin EuO films in the monolayer regime can be produced on the TiO2 surface\nby substrate-supplied oxidation and that such films have bulk-like magnetic\nproperties.",
        "positive": "Engineering magnetic anisotropy and the surface of epitaxial Fe films\n  using ion beam erosion; unveiling self-assembly and tunability: The engineering of surface morphology and structure of the thin film is one\nof the essential technological assets for regulating the physical properties\nand functionalities of thin film-based devices. This study investigates the\nevolution of surface structure and magnetic anisotropy in epitaxially grown\nultrathin Fe films on MgO (001) substrates subjected to multiple cycles of ion\nbeam erosion (IBE) after growth. Ultrathin Fe film grows in 3D island mode and\nexhibits intrinsic fourfold magnetic anisotropy. After a few cycles of IBE, the\nfilm displays an induced uniaxial magnetic anisotropy that leads to a split in\nthe hysteresis loop. In addition, clear and conclusive evidence of IBE mediated\n(2x2) reconstruction of the Fe surface has been observed. We also demonstrate\nthat thermal annealing can reversibly tune the induced UMA and surface\nreconstruction. The feasibility of the IBE technique by properly selecting ion\nbeam parameters for modification of surface structure has been highlighted\napart from conventional methods of tailoring the morphology for tuning of UMA.\nThus, the present work paves a way to explore the IBE-induced self-assembling\nphenomena further."
    },
    {
        "anchor": "Room temperature Ferromagnetism in Th1-xFexO2-d (x = 0.0, 0.05, 0.10,\n  0.15, 0.20 and 0.25) nanoparticles: Nanocrystalline (Th1-xFex)O2-d particles with different Fe concentrations (x\n= 0.0, 0.05, 0.10, 0.15, 0.20 and 0.25) have been prepared by a gel combustion\nmethod. Rietveld refinement analyses of X-ray diffraction data revealed the\nformation of an impurity free cubic type Th1-xFexO2-d structure up to x = 0.20.\nThis observation is further confirmed from the detailed studies conducted on 10\nat. percent Fe doped ThO2 using high-resolution transmission electron\nmicroscopy (HRTEM) imaging and indexing of the selected-area electron\ndiffraction (SAED) patterns. DC Magnetization studies as a function field\nindicate that they are ferromagnetic with Curie temperature (Tc) well above\nroom temperature.",
        "positive": "Magnetic structure and properties of a vanthoffite mineral Na6Mn(SO4)4: A detailed analysis of the magnetic properties of a vanthoffite type mineral\nNa6Mn(SO4)4 basedon dc magnetization, low temperature neutron powder\ndiffraction and theoretical calculations is reported. The mineral crystallizes\nin a monoclinic system with space group P21/c, where MnO6 octahedra are linked\nvia SO4 tetrahedra. This gives rise to super-exchange interaction between two\nMn2+ ions mediated by two nonmagnetic bridging anions and leads to an\nantiferromagnetic ordering below 3 K. The magnetic structure derived from\nneutron powder diffraction at 1.7 K depicts an antiferromagnetic spin\narrangement in the bc plane of the crystal. The magnetic properties are\nmodelled by numerical calculations using exact diagonalization technique, which\nfits the experimental results and provides antiferromagnetic ground state of\nNa6Mn(SO4)4."
    },
    {
        "anchor": "Evidence of a coupled electron-phonon liquid in NbGe$_2$: Whereas electron-phonon scattering typically relaxes the electron's momentum\nin metals, a perpetual exchange of momentum between phonons and electrons\nconserves total momentum and can lead to a coupled electron-phonon liquid with\nunique transport properties. This theoretical idea was proposed decades ago and\nhas been revisited recently, but the experimental signatures of an\nelectron-phonon liquid have been rarely reported. We present evidence of such a\nbehavior in a transition metal ditetrelide, NbGe$_2$, from three different\nexperiments. First, quantum oscillations reveal an enhanced quasiparticle mass,\nwhich is unexpected in NbGe$_2$ due to weak electron-electron correlations,\nhence pointing at electron-phonon interactions. Second, resistivity\nmeasurements exhibit a discrepancy between the experimental data and calculated\ncurves within a standard Fermi liquid theory. Third, Raman scattering shows\nanomalous temperature dependence of the phonon linewidths which fits an\nempirical model based on phonon-electron coupling. We discuss structural\nfactors, such as chiral symmetry, short metallic bonds, and a low-symmetry\ncoordination environment as potential sources of coupled electron-phonon\nliquids.",
        "positive": "Systematic investigation of the structure of the Si(553)-Au surface from\n  first principles: We present here a comprehensive search for the structure of the Si(553)-Au\nreconstruction. More than two hundred different trial structures have been\nstudied using first-principles density-functional calculations with the SIESTA\ncode. An iterative procedure, with a step-by-step increase of the accuracy and\ncomputational cost of the calculations, was used to allow for the study of this\nlarge number of configurations. We have considered reconstructions restricted\nto the topmost bilayer and studied two types: i) \"flat\" surface-bilayer models,\nwhere atoms at the topmost bilayer present different coordinations and\nregistries with the underlying bulk, and ii) nine different models based on the\nsubstitution of a silicon atom by a gold atom in different positions of a\n$\\pi$-bonded chain reconstruction of the Si(553) surface. We have developed a\ncompact notation that allows us to label and identify all these structures.\nThis is very useful for the automatic generation of trial geometries and\ncounting the number of inequivalent structures, i.e., structures having\ndifferent bonding topologies. The most stable models are those that exhibit a\nhoneycomb-chain structure at the step edge. One of our models (model f2)\nreproduces the main features of the room temperature photoemission and\nscanning-tunneling microscopy data. Thus we conclude that f2 structure is a\ngood candidate for the high temperature structure of the Si(553)-Au surface."
    },
    {
        "anchor": "Optical nonlinearity enhancement of graded metal-dielectric composite\n  films: We have derived the local electric field inside graded metal-dielectric\ncomposite films with weak nonlinearity analytically, which further yields the\neffective linear dielectric constant and third-order nonlinear susceptibility\nof the graded structures. As a result, the composition-dependent gradation can\nproduce a broad resonant plasmon band in the optical region, resulting in a\nlarge enhancement of the optical nonlinearity and hence a large figure of\nmerit.",
        "positive": "A two-species continuum model for aeolian sand ripples: We formulate a continuum model for aeolian sand ripples consisting of two\nspecies of grains: a lower layer of relatively immobile clusters, with an upper\nlayer of highly mobile grains moving on top. We predict analytically the ripple\nwavelength, initial ripple growth rate and threshold saltation flux for ripple\nformation. Numerical simulations show the evolution of realistic ripple\nprofiles from initial surface roughness via ripple growth and merger."
    },
    {
        "anchor": "Water and Ion Transfer to Narrow Carbon Nanotubes: Roles of Exterior and\n  Interior: Narrow carbon nanotubes (CNTs) desalinate water, mimicking water channels of\nbiological membranes, yet the physics behind selectivity, especially, the\neffect of the membrane embedding CNTs on water and ion transfer, is still\nunclear. Here, we report $ab$ $initio$ analysis of the energies involved in\ntransfer of water and K$^+$ and Cl$^-$ ions from solution to empty and\nwater-filled 0.68 nm CNTs, for different dielectric constants $\\epsilon$ of the\nsurrounding matrix. The transfer energies computed for $1 \\leq \\epsilon <\n\\infty$ permit a transparent breakdown of the transfer energy to three main\ncontributions: binding to CNT, intra-CNT hydration, and dielectric polarization\nof the matrix. The latter scales inversely with $\\epsilon$ and is of the order\n$10^2$/$\\epsilon$ kJ/mol for both ions, which may change ion transfer from\nfavorable to unfavorable, depending on ion, $\\epsilon$, and CNT diameter. This\nmay have broad implications for designing and tuning selectivity of\nnanochannel-based devices.",
        "positive": "Engineering and improving the magnetic properties of thin Fe layers\n  through exchange coupling with hard magnetic Dysprosium layers: We report on a comprehensive study of the magnetic coupling between soft\nmagnetic Fe layers and hard magnetic Dysprosium (Dy) layers at low temperatures\n(4.2 - 120K). For our experiments we prepared thin films of Fe and Dy and\nmultilayers of Fe/Dy by ultra-high vacuum sputtering. The magnetic properties\nof each material were determined with a superconducting quantum interference\ndevice. Furthermore, we performed magnetoresistance measurements with similarly\ngrown, microstructured devices, where the anisotropic magnetoresistance (AMR)\neffect was used to identify the magnetization state of the samples. By\nanalyzing and comparing the corresponding data of Fe and Dy, we show that the\npresence of a Dy layer on top of the Fe layer significantly influences its\nmagnetic properties and makes it magnetically harder. We perform a systematic\nevaluation of this effect and its dependence on temperature and on the\nthickness of the soft magnetic layer. All experimental results can consistently\nbe explained with exchange coupling at the interface between the Fe and the Dy\nlayer. Our experiments also yield a negative sign of the AMR effect of thin Dy\nfilms, and an increase of the Dy films' Curie temperature, which is due to\ngrowth conditions."
    },
    {
        "anchor": "Superdiffusive heat conduction in semiconductor alloys -- II. Truncated\n  L\u00e9vy formalism for experimental analysis: Nearly all experimental observations of quasi-ballistic heat flow are\ninterpreted using Fourier theory with modified thermal conductivity. Detailed\nBoltzmann transport equation (BTE) analysis, however, reveals that the\nquasi-ballistic motion of thermal energy in semiconductor alloys is no longer\nBrownian but instead exhibits L\\'evy dynamics with fractal dimension $\\alpha <\n2$. Here, we present a framework that enables full 3D experimental analysis by\nretaining all essential physics of the quasi-ballistic BTE dynamics\nphenomenologically. A stochastic process with just two fitting parameters\ndescribes the transition from pure L\\'evy superdiffusion as short length and\ntime scales to regular Fourier diffusion. The model provides accurate fits to\ntime domain thermoreflectance raw experimental data over the full modulation\nfrequency range without requiring any `effective' thermal parameters and\nwithout any a priori knowledge of microscopic phonon scattering mechanisms.\nIdentified $\\alpha$ values for InGaAs and SiGe match ab initio BTE predictions\nwithin a few percent. Our results provide experimental evidence of fractal\nL\\'evy heat conduction in semiconductor alloys. The formalism additionally\nindicates that the transient temperature inside the material differs\nsignificantly from Fourier theory and can lead to improved thermal\ncharacterization of nanoscale devices and material interfaces.",
        "positive": "Structure, stability and defects of single layer h-BN in comparison to\n  graphene: We study by molecular dynamics the structural properties of single layer h-BN\nin comparison to graphene. We show that the Tersoff bond order potential\ndeveloped for BN by Albe, Moller and Heinig gives a thermally stable hexagonal\nsingle layer with a bending constant kappa= 0.54 eV at T = 0. We find that the\nnon-monotonic behaviour of the lattice parameter, the expansion of the\ninteratomic distance and the growth of the bending rigidity with temperature\nare qualitatively similar to those of graphene. Conversely, the energetics of\npoint defects is extremely different: instead of Stone Wales defects, the two\nlowest energy defects in h-BN involve either a broken bond or an out of plane\ndisplacement of a N atom to form a tetrahedron with three B atoms in the plane.\nWe provide the formation energies and an estimate of the energy barriers."
    },
    {
        "anchor": "Single-Crystalline Metallic Films Induced by van der Waals Epitaxy on\n  Black Phosphorus: The properties of metal-semiconductor junctions are often unpredictable\nbecause of non-ideal interfacial structures, such as interfacial defects or\nchemical reactions introduced at junctions. Black phosphorus (BP), an elemental\ntwo-dimensional (2D) semiconducting crystal, possesses the puckered atomic\nstructure with high chemical reactivity, and the establishment of a realistic\natomic-scale picture of BP's interface toward metallic contact has remained\nelusive. Here we examine the interfacial structures and properties of\nphysically-deposited metals of various kinds on BP. We find that Au, Ag, and Bi\nform single-crystalline films with (110) orientation through guided van der\nWaals epitaxy. Transmission electron microscopy and X-ray photoelectron\nspectroscopy confirm that atomically sharp van der Waals metal-BP interfaces\nforms with exceptional rotational alignment. Under a weak metal-BP interaction\nregime, the BP's puckered structure play an essential role in the adatom\nassembly process and can lead to the formation of a single crystal, which is\nsupported by our theoretical analysis and calculations. The experimental survey\nalso demonstrates that the BP-metal junctions can exhibit various types of\ninterfacial structures depending on metals, such as the formation of\npolycrystalline microstructure or metal phosphides. This study provides a\nguideline for obtaining a realistic view on metal-2D semiconductor interfacial\nstructures, especially for atomically puckered 2D crystals.",
        "positive": "Combining Landau Zener Theory and Kinetic Monte Carlo Sampling for Small\n  Polaron Mobility of Doped BiVO4: Transition metal oxides such as \\ce{BiVO4} are promising materials as\nphotoelectrodes in solar-to-fuel conversion applications. However, their\nperformance is limited by the low carrier mobility (especially electron\nmobility) due to the formation of small polarons. Recent experimental studies\nshow improved carrier mobility and conductivity by atomic dopings. We studied\nthe small polaron hopping mobility in pristine and doped \\ce{BiVO4} by\ncombining Landau-Zener theory and kinetic Monte Carlo (kMC) simulation fully\nfrom first-principles, and investigated the effect of dopant-polaron\ninteractions on the mobility. We found polarons are spontaneously formed at V\nin both pristine and Mo/W doped \\ce{BiVO4}, which can only be described\ncorrectly by density function theory (DFT) with the Hubbard correction (DFT+U)\nor hybrid exchange-correlation functional but not local or semi-local\nfunctionals. We found DFT+U and dielectric dependant hybrid functional (DDH)\ngive similar electron hopping barriers, which are also similar between the room\ntemperature monoclinic phase and the tetragonal phase. The calculated electron\nmobility agrees well with experimental values, which is around $10^{-4}$\ncm$^2$V$^{-1}$s$^{-1}$. We found the electron polaron transport in \\ce{BiVO4}\nis neither fully adiabatic nor nonadiabatic, and the first and second nearest\nneighbor hoppings have significantly different adiabacity in spite of similar\nhopping barriers. We further computed polaron mobility in the presence of\ndifferent dopants and showed that Cr substitution of V is an electron trap\nwhile Mo and W are \"repulsive\" centers, mainly due to the minimization of local\nlattice expansion by dopants and electron polarons. The dopants with\n\"repulsive\" interactions to polarons are promising for mobility improvement due\nto larger wavefunction overlap and delocalization of locally concentrated\npolarons."
    },
    {
        "anchor": "What is the valence of Mn in Ga$_{1-x}$Mn$_x$N?: We investigate the current debate on the Mn valence in Ga$_{1-x}$Mn$_x$N, a\ndiluted magnetic semiconductor (DMSs) with a potentially high Curie\ntemperature. From a first-principles Wannier-function analysis, we\nunambiguously find the Mn valence to be close to $2+$ ($d^5$), but in a mixed\nspin configuration with average magnetic moments of 4$\\mu_B$. By integrating\nout high-energy degrees of freedom differently, we further derive for the first\ntime from first-principles two low-energy pictures that reflect the intrinsic\ndual nature of the doped holes in the DMS: 1) an effective $d^4$ picture ideal\nfor local physics, and 2) an effective $d^5$ picture suitable for extended\nproperties. In the latter, our results further reveal a few novel physical\neffects, and pave the way for future realistic studies of magnetism. Our study\nnot only resolves one of the outstanding key controversies of the field, but\nalso exemplifies the general need for multiple effective descriptions to\naccount for the rich low-energy physics in many-body systems in general.",
        "positive": "Reliable operation of Cr$_2$O$_3$:Mg/ $\u03b2$-Ga$_2$O$_3$ p-n\n  heterojunction diodes at 600$^\\circ$C: $\\beta$-Ga$_2$O$_3$-based semiconductor heterojunctions have recently\ndemonstrated improved performance at high voltages and elevated temperatures\nand are thus promising for applications in power electronic devices and\nharsh-environment sensors. However, the long-term reliability of these\nultra-wide band gap (UWBG) semiconductor devices remains barely addressed and\nmay be strongly influenced by chemical reactions at the p-n heterojunction\ninterface. Here, we experimentally demonstrate operation and evaluate the\nreliability of Cr$_2$O$_3$:Mg/ $\\beta$-Ga$_2$O$_3$ p-n heterojunction diodes at\nduring extended operation at 600$^\\circ$C, as well as after 30 repeated cycles\nbetween 25-550$^\\circ$C. The calculated pO2-temperature phase stability diagram\nof the Ga-Cr-O material system predicts that Ga$_2$O$_3$ and Cr$_2$O$_3$ should\nremain thermodynamically stable in contact with each other over a wide range of\noxygen pressures and operating temperatures. The fabricated Cr$_2$O$_3$:Mg /\n$\\beta$-Ga$_2$O$_3$ p-n heterojunction diodes show room-temperature on/off\nratios >10$^4$ at $\\pm$5V and a breakdown voltage (V$_{Br}$) of -390V. The\nleakage current increases with increasing temperature up to 600$^\\circ$C, which\nis attributed to Poole-Frenkel emission with a trap barrier height of 0.19 eV.\nOver the course of a 140-hour thermal soak at 600$^\\circ$C, both the device\nturn-on voltage and on-state resistance increase from 1.08V and 5.34\nm$\\Omega$-cm$^2$ to 1.59V and 7.1 m$\\Omega$-cm$^2$ respectively. This increase\nis attributed to the accumulation of Mg and MgO at the Cr$_2$O$_3$/Ga$_2$O$_3$\ninterface as observed from TOF-SIMS analysis. These findings inform future\ndesign strategies of UWBG semiconductor devices for harsh environment operation\nand underscore the need for further reliability assessments for\n$\\beta$-Ga$_2$O$_3$ based devices."
    },
    {
        "anchor": "Understanding XANES spectra of two-temperature warm dense copper using\n  ab initio simulation: Using ab initio molecular-dynamics simulations combined with linear-response\ntheory, we studied the x-ray absorption near-edge spectra (XANES) of a\ntwo-temperature dense copper plasma. As the temperature increases, XANES\nspectra exhibit a pre-edge structure balanced by a reduction of the absorption\njust behind the edge. By performing systematic simulations for various\nthermodynamic conditions, we establish a formulation to deduce the electronic\ntemperature Te directly from the spectral integral of the pre-edge that can be\nused for various thermodynamic conditions encountered in a femtosecond heating\nexperiment where thermal non equilibrium and expanded states have to be\nconsidered.",
        "positive": "Temperature-dependent Gilbert damping of Co2FeAl thin films with\n  different degree of atomic order: Half-metallicity and low magnetic damping are perpetually sought for in\nspintronics materials and full Heusler alloys in this respect provide\noutstanding properties. However, it is challenging to obtain the well-ordered\nhalf-metallic phase in as-deposited full Heusler alloys thin films and theory\nhas struggled to establish a fundamentals understanding of the temperature\ndependent Gilbert damping in these systems. Here we present a study of the\ntemperature dependent Gilbert damping of differently ordered as-deposited\nCo2FeAl full Heusler alloy thin films. The sum of inter- and intraband electron\nscattering in conjunction with the finite electron lifetime in Bloch states\ngovern the Gilbert damping for the well-ordered phase in contrast to the\ndamping of partially-ordered and disordered phases which is governed by\ninterband electronic scattering alone. These results, especially the ultralow\nroom temperature intrinsic damping observed for the well-ordered phase provide\nnew fundamental insights to the physical origin of the Gilbert damping in full\nHeusler alloy thin films."
    },
    {
        "anchor": "Self-energy of dislocations and dislocation pileups: A continuum model of dislocation pileups that takes the self-energy of\ndislocations into account is proposed. An analytical solution describing the\ndistribution of dislocations in equilibrium is found from the energy\nminimization. Based on this solution we show (i) the existence of a critical\nthreshold stress for the equilibrium of dislocations within a double pileup,\nand (ii) the existence of a non-linear regime in which the number of\ndislocations in a double pileup does not scale linearly with the resolved\nexternal shear stress, contrary to the classical double pileup model.",
        "positive": "Issues and Challenges in Orbital-free Density Functional Calculations: Solving the Euler equation which corresponds to the energy minimum of a\ndensity functional expressed in orbital-free form involves related but distinct\ncomputational challenges. One is the choice between all-electron and\npseudo-potential calculations and, if the latter, construction of the\npseudo-potential. Another is the stability, speed, and accuracy of solution\nalgorithms. Underlying both is the fundamental issue of satisfactory quality of\nthe approximate functionals (kinetic energy and exchange-correlation). We\naddress both computational issues and illustrate them by some comparative\nperformance testing of our recently developed modified-conjoint generalized\ngradient approximation kinetic energy functionals. Comparisons are given for\natoms, diatomic molecules, and some simple solids."
    },
    {
        "anchor": "Anisotropic thermal expansion of AEFe2As2 (AE = Ba, Sr, Ca) single\n  crystals: We report anisotropic thermal expansion of the parent, AEFe2As2 (AE = Ba, Sr,\nand Ca), compounds. Above the structural/antiferromagnetic phase transition\nanisotropy of the thermal expansion coefficients is observed, with the\ncoefficient along the a-axis being significantly smaller than the coefficient\nfor the c-axis. The high temperature (200 K < T < 300 K) coefficients\nthemselves have similar values for the compounds studied. The sharp anomalies\nassociated with the structural/antiferromagnetic phase transitions are clearly\nseen in the thermal expansion measurements. For all three pure compounds the\n\"average\" a-value increases and the c-lattice parameter decreases on warming\nthrough the transition with the smallest change in the lattice parameters\nobserved for SrFe2As2. The data are in general agreement with the literature\ndata from X-ray and neutron diffraction experiments.",
        "positive": "Theory of electron-plasmon coupling in semiconductors: The ability to manipulate plasmons is driving new developments in\nelectronics, optics, sensing, energy, and medicine. Despite the massive\nmomentum of experimental research in this direction, a predictive\nquantum-mechanical framework for describing electron-plasmon interactions in\nreal materials is still missing. Here, starting from a many-body Green's\nfunction approach, we develop an ab initio approach for investigating\nelectron-plasmon coupling in solids. As a first demonstration of this\nmethodology, we show that electron-plasmon scattering is the primary mechanism\nfor the cooling of hot carriers in doped silicon, it is key to explain measured\nelectron mobilities at high doping, and it leads to a quantum zero-point\nrenormalization of the band gap in agreement with experiment."
    },
    {
        "anchor": "Phonon modes and Raman signatures of MnBi2nTe3n+1 (n=1,2,3,4) magnetic\n  topological heterostructures: An intrinsic antiferromagnetic topological insulator $\\mathrm{MnBi_2Te_4}$\ncan be realized by intercalating Mn-Te bilayer chain in a topological\ninsulator, $\\mathrm{Bi_2Te_3}$. $\\mathrm{MnBi_2Te_4}$ provides not only a\nstable platform to demonstrate exotic physical phenomena, but also easy\ntunability of the physical properties. For example, inserting more\n$\\mathrm{Bi_2Te_3}$ layers in between two adjacent $\\mathrm{MnBi_2Te_4}$\nweakens the interlayer magnetic interactions between the $\\mathrm{MnBi_2Te_4}$\nlayers. Here we present the first observations on the inter- and intra-layer\nphonon modes of $\\mathrm{MnBi_{2n}Te_{3n+1}}$ (n=1,2,3,4) using cryogenic\nlow-frequency Raman spectroscopy. We experimentally and theoretically\ndistinguish the Raman vibrational modes using various polarization\nconfigurations. The two peaks at 66 cm$^{-1}$ and 112 cm$^{-1}$ show an\nabnormal perturbation in the Raman linewidths below the magnetic transition\ntemperature due to spin-phonon coupling. In $\\mathrm{MnBi_4Te_7}$, the\n$\\mathrm{Bi_2Te_3}$ layers induce Davydov splitting of the A$_{1g}$ mode around\n137 cm$^{-1}$ at 5 K. Using the linear chain model, we estimate the\nout-of-plane interlayer force constant to be $(3.98 \\pm 0.14) \\times 10^{19}$\nN/m$^3$ at 5 K, three times weaker than that of $\\mathrm{Bi_2Te_3}$. Our work\ndiscovers the dynamics of phonon modes of the $\\mathrm{MnBi_2Te_4}$ and the\neffect of the additional $\\mathrm{Bi_2Te_3}$ layers, providing the\nfirst-principles guidance to tailor the physical properties of layered\nheterostructures.",
        "positive": "Failure Processes in Embedded Monolayer Graphene under Axial Compression: Exfoliated monolayer graphene flakes were embedded in a polymer matrix and\nloaded under axial compression. By monitoring the shifts of the 2D Raman\nphonons of rectangular flakes of various sizes under load, the critical strain\nto failure was determined. Prior to loading care was taken for the examined\narea of the flake to be free of residual stresses. The critical strain values\nfor first failure were found to be independent of flake size at a mean value of\n-0.60 % corresponding to a yield stress of -6 GPa. By combining Euler mechanics\nwith a Winkler approach, we show that unlike buckling in air, the presence of\nthe polymer constraint results in graphene buckling at a fixed value of strain\nwith an estimated wrinkle wavelength of the order of 1-2 nm. These results were\ncompared with DFT computations performed on analogue coronene/ PMMA oligomers\nand a reasonable agreement was obtained."
    },
    {
        "anchor": "Continuous melting and thermal-history-dependent freezing in the\n  confined Na-K eutectic alloy: 23Na NMR studies of the Na-K eutectic alloy embedded into porous glass with 7\nnm pores showed that melting of Na2K confined nanoparticles is a continuous\nprocess with smooth changes in the Knight shift of a narrow resonance line and\nnuclear spin relaxation between those in the crystalline and liquid states. The\nintermediate state which occurs upon melting is stable and more favorable than\nthe liquid state. The inverse freezing transformation can be sharp as at a\nfirst order transition or continuous depending on the initial temperature of\ncooling. The results suggest revision of theoretical predictions for the\nmelting and freezing transitions in confined geometry.",
        "positive": "Ultra-broadband photodetection of Weyl semimetal TaAs up to infrared 10\n  \u03bcm range at room temperature: Photodetectors with broadband optical response have promising applications in\nmany advanced optoelectronic and photonic devices. Especially, those with the\ndetection range up to mid-infrared at room temperature are very challenging and\nhighly desired. Recently, Weyl semimetal has been discovered and proposed to be\nfavorable for photodetection since in general it breaks Lorentz invariance to\nhave tilted chiral Weyl cones around Fermi level, which leads to chirality\ndependent photocurrents at arbitrarily long wavelength. Furthermore, the linear\ndispersion bands in Weyl cones result in very high carrier mobility and much\nreduced thermal carrier compared with the parabolic ones in narrow-gap\nsemiconductors. Here, we report that the Weyl semimetal TaAs based\nphotodetector can operate at room temperature with spectral range from blue\n(438.5 nm) to mid-infrared (10.29 {\\mu}m) light wavelengths and the\nresponsibility and detectivity is more than 78 uA W-1 and 1.88*107 Jones,\nrespectively. This is the first photodetector made by a Weyl semimetal and\nshows its promising in room-temperature mid-infrared photodetection."
    },
    {
        "anchor": "Spin-Orbit Coupling and Ion Displacements in Multiferroic TbMnO3: The electronic and magnetic properties of TbMnO3 leading to its ferroelectric\n(FE) polarization were investigated on the basis of relativistic density\nfunctional theory (DFT) calculations. In agreement with experiment, we show\nthat the spin-spiral plane of TbMnO3 can be either the bc- or ab-plane, but not\nthe ac-plane. As for the mechanism of FE polarization, our work reveals that\nthe \"pure electronic\" model by Katsura, Nagaosa and Balatsky (KNB) is\ninadequate in predicting the absolute direction of FE polarization. For the\nab-plane spin-spiral state of TbMnO3, the direction of FE polarization\npredicted by the KNB model is opposite to that predicted by DFT calculations.\nIn determining the magnitude and the absolute direction of FE polarization in\nspin-spiral states, it is found crucial to consider the displacements of the\nions from their ecntrosymmetric positions.",
        "positive": "Influence of amorphous phase on coercivity in SmCo5-Cu nanocomposites: Severe plastic deformation of powder blends consisting of SmCo5-Cu results in\nmagnetically hardened nanocomposite bulk materials. The microstructure is\ncontinuously refined with increasing torsional deformation, yet, coercivity\nsaturates at a certain level of strain. Transmission electron microscopy (TEM)\ninvestigation of the microstructure reveals a partial amorphization of the\nSmCo5 phase due to high-pressure torsion by 20 applied rotations. In this\namorphous matrix nanocrystals are embedded. The effect of these experimentally\nobserved microstructural features on the magnetic properties are investigated\nby micromagnetic simulations, which show that an increasing volume fraction of\nnanocrystals is beneficial for higher coercivities. For a fixed volume fraction\nof nanocrystals the simulations reveal an increasing coercivity with decreasing\nthe size of the nanocrystals due to increasing number of interfaces acting as\npinning sites. Furthermore, our micromagnetic simulations disclose the\nmechanisms of the saturation and decline of magnetic hardening due to the\nstrain induced by high-pressure torsion. The calculated coercivity fits very\nwell to the experimentally observed coercivity of Hc=1.34 T. The knowledge can\nalso be used to develop and provide optimization strategies from the\nmicrostructure perspective."
    },
    {
        "anchor": "Spin dynamics of electrons in the first excited subband of a\n  high-mobility low-density 2D electron system: We report on time-resolved Kerr rotation measurements of spin coherence of\nelectrons in the first excited subband of a high-mobility low-density\ntwo-dimensional electron system in a GaAs/Al0.35Ga0.65As heterostructure. While\nthe transverse spin lifetime (T2*) of electrons decreases monotonically with\nincreasing magnetic field, it has a non-monotonic dependence on the\ntemperature, with a peak value of 596 ps at 36 K, indicating the effect of\ninter-subband electron-electron scattering on the electron spin relaxation. The\nspin lifetime may be long enough for potential device application with\nelectrons in excited subbands.",
        "positive": "The Complex Systems and Biomedical Sciences group at the ESRF: current\n  status and new opportunities after Extremely Brilliant Source upgrade: The Complex System and Biomedical Sciences (CBS) group at the European\nSynchrotron Radiation Facility (ESRF) in Grenoble is dedicated to the study of\na broad family of materials and systems, including soft and hard condensed\nmatter, nanomaterials, and biological materials. The main experimental methods\nused for this purpose are X-ray diffraction, reflectivity, scattering, photon\ncorrelation spectroscopy, and time-resolved X-ray scattering/diffraction. After\na recent and successful Extremely Brilliant Source (EBS) upgrade, the Grenoble\nsynchrotron has become the first of the 4th generation high energy facilities,\nwhich offers unprecedented beam parameters for its user community, bringing new\nexperimental opportunities for the exploration of the nanoscale structure,\nkinetics, and dynamics of a myriad of systems. In this contribution, we present\nthe impact of the recent upgrade on the selected beamlines in the CBS group and\na summary of recent scientific activities after the facility reopening."
    },
    {
        "anchor": "Elastic properties of cubic crystals: Every's versus Blackman's diagram: Blackman's diagram of two dimensionless ratios of elastic constants is\nfrequently used to correlate elastic properties of cubic crystals with\ninteratomic bondings. Every's diagram of a different set of two dimensionless\nvariables was used by us for classification of various properties of such\ncrystals. We compare these two ways of characterization of elastic properties\nof cubic materials and consider the description of various groups of materials,\ne.g. simple metals, oxides, and alkali halides. With exception of intermediate\nvalent compounds, the correlation coefficients for Every's diagrams of various\ngroups of materials are greater than for Blackaman's diagrams, revealing the\nexistence of a linear relationship between two dimensionless Every's variables.\nAlignment of elements and compounds along lines of constant Poisson's ratio\n$\\nu(<100>,\\textbf{m})$, ($\\textbf{m}$ arbitrary perpendicular to <100>) is\nobserved. Division of the stability region in Blackman's diagram into region of\ncomplete auxetics, auxetics and non-auxetics is introduced. Correlations of a\nscaling and an acoustic anisotropy parameter are considered.",
        "positive": "Polaron transport and thermoelectric behavior in La-doped SrTiO3 thin\n  films with elemental vacancies: Electrodynamic properties of La-doped SrTiO3 thin films with controlled\nelemental vacancies have been investigated using optical spectroscopy and\nthermopower measurement. In particular, we observed a correlation between the\npolaron formation and thermoelectric properties of the transition metal oxide\n(TMO) thin films. With decreasing oxygen partial pressure during the film\ngrowth (P(O2)), a systematic lattice expansion was observed along with the\nincreased elemental vacancy and carrier density, experimentally determined\nusing optical spectroscopy. Moreover, we observed an absorption in the\nmid-infrared photon energy range, which is attributed to the polaron formation\nin the doped SrTiO3 system. Thermopower of the La-doped SrTiO3 thin films could\nbe largely modulated from -120 to -260 {\\mu}V K-1, reflecting an enhanced\npolaronic mass of ~3 < mpolron/m < ~4. The elemental vacancies generated in the\nTMO films grown at various P(O2) influences the global polaronic transport,\nwhich governs the charge transport behavior, including the thermoelectric\nproperties."
    },
    {
        "anchor": "Microstructure and interface studies of LaVO3/SrVO3 superlattices: The structure and interface characteristics of (LaVO3)6m(SrVO3)m\nsuperlattices deposited on (100)-SrTiO3 (STO) substrate were studied using\nTransmission Electron Microscopy (TEM). Cross-section TEM studies revealed that\nboth LaVO3 (LVO) and SrVO3 (SVO) layers are good single crystal quality and\nepitaxially grown with respect to the substrate. It is evidenced that LVO\nlayers are made of two orientational variants of a distorted perovskite\ncompatible with bulk LaVO3 while SVO layers suffers from a tetragonal\ndistortion due to the substrate induced stain. Electron Energy Loss\nSpectroscopy (EELS) investigations indicate changes in the fine structure of\nthe V L23 edge, related to a valence change between the LaVO3 and SrVO3 layers.",
        "positive": "Signature of Hanle Precession in Trilayer MoS2: Theory and Experiment: Valley-spin coupling in transition-metal dichalcogenides (TMDs) can result in\nunusual spin transport behaviors under an external magnetic field. Nonlocal\nresistance measured from 2D materials such as TMDs via electrical Hanle\nexperiments are predicted to exhibit nontrivial features, compared with results\nfrom conventional materials due to the presence of intervalley scattering as\nwell as a strong internal spin-orbit field. Here, for the first time, we report\nthe all-electrical injection and non-local detection of spin polarized carriers\nin trilayer MoS_2 films. We calculate the Hanle curves theoretically when the\nseparation between spin injector and detector is much larger than spin\ndiffusion length, \\lamda_s. The experimentally observed curve matches the\ntheoretically-predicted Hanle shape under the regime of slow intervalley\nscattering. The estimated spin life-time was found to be around 110 ps at 30 K."
    },
    {
        "anchor": "Manipulating Multiple Order Parameters via Oxygen Vacancies: The case of\n  Eu0.5Ba0.5TiO3-\u03b4: Controlling functionalities, such as magnetism or ferroelectricity, by means\nof oxygen vacancies (VO) is a key issue for the future development of\ntransition metal oxides. Progress in this field is currently addressed through\nVO variations and their impact on mainly one order parameter. Here we reveal a\nnew mechanism for tuning both magnetism and ferroelectricity simultaneously by\nusing VO. Combined experimental and density-functional theory studies of\nEu0.5Ba0.5TiO3-{\\delta}, we demonstrate that oxygen vacancies create Ti3+ 3d1\ndefect states, mediating the ferromagnetic coupling between the localized Eu\n4f7 spins, and increase an off-center displacement of Ti ions, enhancing the\nferroelectric Curie temperature. The dual function of Ti sites also promises a\nmagnetoelectric coupling in the Eu0.5Ba0.5TiO3-{\\delta}.",
        "positive": "Multi-modal Spectroscopic Study of Surface Termination Evolution in\n  Cr2TiC2Tx MXene: Control of surface functionalization of MXenes holds great potential, and in\nparticular, may lead to tuning of magnetic and electronic order in the recently\nreported magnetic Cr2TiC2Tx. Here, vacuum annealing experiments of Cr2TiC2Tx\nare reported with in situ electron energy loss spectroscopy and novel in situ\nCr K-edge extended energy loss fine structure analysis, which directly tracks\nthe evolution of the MXene surface coordination environment. These in situ\nprobes are accompanied by benchmarking synchrotron X-ray absorption fine\nstructure measurements and density functional theory calculations. With the\netching method used here, the MXene has an initial termination chemistry of\nCr2TiC2O1.3F0.8. Annealing to 600 C results in the complete loss of -F, but -O\ntermination is thermally stable up to (at least) 700 C. These findings\ndemonstrate thermal control of -F termination in Cr2TiC2Tx and offer a first\nstep towards termination engineering this MXene for magnetic applications.\nMoreover, this work demonstrates high energy electron spectroscopy as a\npowerful approach for surface characterization in 2D materials."
    },
    {
        "anchor": "Threshold displacement energy map of Frenkel pair generation in $\\rm\n  Ga_2O_3$ from machine-learning-driven molecular dynamics simulations: $\\beta$ phase gallium oxide ($\\beta$-$\\rm Ga_2O_3$) demonstrates tremendous\npotential for electronics applications and offers promising prospects for\nintegration into future space systems with the necessity of high radiation\nresistance. Therefore, a comprehensive understanding of the threshold\ndisplacement energy (TDE) and the radiation-induced formation of Frenkel pairs\n(FPs) in this material is vital but has not yet been thoroughly studied. In\nthis work, we performed over 5,000 molecular dynamics simulations using our\nmachine-learning potentials to determine the TDE and investigate the formation\nof FPs. The average TDEs for the two Ga sites, Ga1 (tetrahedral site) and Ga2\n(octahedral site), are 22.9 and 20.0 eV, respectively. While the average TDEs\nfor the three O sites are nearly uniform, ranging from 17.0 to 17.4 eV. The\ngenerated TDE maps reveal significant differences in displacement behavior\nbetween these five atomic sites. Our developed defect identification methods\nsuccessfully categorize various types of FPs in this material, with more than\nten types of Ga FPs being produced during our simulations. O atoms are found to\nform two main types of FPs and the O split interstitial site on O1 site is most\ncommon. Finally, the recombination behavior and barriers of Ga and O FPs\nindicate that the O FP has a higher possibility of recovery upon annealing. Our\nfindings provide important insights into the studies of radiation damage and\ndefects in $\\rm Ga_2O_3$ and can contribute to the design and development of\n$\\rm Ga_2O_3$-based devices",
        "positive": "Schwarzite and schwarzynes based load-bear resistant radial cellular\n  griding-based 3D printed structures: Nature-occurring structures exhibiting unique topological features such as\ncomplex and gradient porosity has been the basis to create new materials and/or\nstructures. Most studies have been focused on complex periodic porous\nstructures but gradient porous ones have not been yet fully investigated for\nstable structural designs. In this work, we have proposed and tested a new\napproach to create cellular griding structures, in which the mass density\nvaries from the center to the borders, i.e, a radial gradient. To create these\nnew structures we exploited the topology of two carbon-based families with\ndifferent pore sizes, the schwarzites, and schwarzynes. We created fully\natomistic models that were translated into macroscale ones that were then 3D\nprinted. The mechanical behavior of the gradient structures was investigated by\nmolecular dynamics simulations and mechanical compression tests of the printed\nmodels. Our results show that their mechanical response can be engineered (for\ninstance, in terms of energy absorption, ballistic performance, etc.) and can\noutperform their corresponding density uniform structures."
    },
    {
        "anchor": "Wave-diffusion theory of spin transport in metals after ultrashort-pulse\n  excitation: Spin and charge-current dynamics after ultrafast spin-polarized excitation in\na normal metal are studied theoretically using a wave-diffusion theory. It is\nshown analytically how this macroscopic approach correctly describes the\nballistic and diffusive properties of spin and charge transport, but also\napplies to the intermediate regime between these two limits. Using the\nwave-diffusion equations we numerically analyze spin and charge dynamics after\nultrafast excitation of spin polarized carriers in thin gold films. Assuming\nslightly spin-dependent momentum relaxation times, we find that a unified\ntreatment of diffusive and ballistic transport yields robust signatures in the\nspin and charge dynamics, which are in qualitative agreement with recent\nexperimental results [Phys. Rev. Lett 107, 076601 (2011)]. The influence of\nboundary effects on the temporal signatures of spin transport is also studied.",
        "positive": "Measuring a population of spin waves from the electrical noise of an\n  inductively coupled antenna: We study how a population of spin waves can be characterized from the\nanalysis of the electrical microwave noise delivered by an inductive antenna\nplaced in its vicinity. The measurements are conducted on a synthetic\nantiferromagnetic thin stripe covered by a micron-sized antenna that feeds a\nspectrum analyser after amplification. The antenna noise contains two\ncontributions. The population of incoherent spin waves generates a fluctuating\nfield that is sensed by the antenna: this is the \"magnon noise\". The antenna\nnoise also contains the contribution of the electronic fluctuations: the\nJohnson-Nyquist noise. The latter depends on all impedances within the\nmeasurement circuit, which includes the antenna self-inductance. As a result,\nthe electronic noise contains information about the magnetic susceptibility of\nthe stripe, though it does not inform on the absolute amplitude of the magnetic\nfluctuations. For micrometer-sized systems at thermal equilibrium, the\nelectronic noise dominates and the pure magnon noise cannot be determined. If\nin contrast the spinwave bath is not at thermal equilibrium with the\nmeasurement circuit, and if the spin wave population can be changed then one\ncould measure a mode-resolved effective magnon temperature provided specific\nprecautions are implemented."
    },
    {
        "anchor": "Interaction of excitons with magnetic topological defects in 2D magnetic\n  monolayers: localization and anomalous Hall effect: Novel 2D material CrI3 reveals unique combination of 2D ferromagnetism and\nrobust excitonic response. We demonstrate that the possibility of the formation\nof magnetic topological defects, such as Neel skyrmions, together with large\nexcitonic Zeeman splitting, leads to giant scattering asymmetry, which is the\nnecessary prerequisite for the excitonic anomalous Hall effect. In addition,\nthe diamagnetic effect breaks the inversion symmetry, and in certain cases can\nresult in exciton localization on the skyrmion. This enables the formation of\nmagnetoexcitonic quantum dots with tunable parameters.",
        "positive": "Channel Length Scaling of MoS2 MOSFETs: In this article, we investigate electrical transport properties in ultrathin\nbody (UTB) MoS2 two-dimensional (2D) crystals with channel lengths ranging from\n2 {\\mu}m down to 50 nm. We compare the short channel behavior of sets of\nMOSFETs with various channel thickness, and reveal the superior immunity to\nshort channel effects of MoS2 transistors. We observe no obvious short channel\neffects on the device with 100 nm channel length (Lch) fabricated on a 5 nm\nthick MoS2 2D crystal even when using 300 nm thick SiO2 as gate dielectric, and\nhas a current on/off ratio up to ~109. We also observe the on-current\nsaturation at short channel devices with continuous scaling due to the carrier\nvelocity saturation. Also, we reveal the performance limit of short channel\nMoS2 transistors is dominated by the large contact resistance from the Schottky\nbarrier between Ni and MoS2 interface, where a fully transparent contact is\nneeded to achieve a high-performance short channel device."
    },
    {
        "anchor": "Positive temperature-dependent thermal conductivity induced by wavelike\n  phonons in complex Ag-based argyrodites: The phonon transport mechanisms and the anomalous temperature-dependent\nlattice thermal conductivities (kL) in Ag-based argyrodites have not been fully\nunderstood. Herein, we systematically study the phonon thermal transport of\nfive Ag-based crystalline argyrodites Ag7PS6, Ag7AsS6, Ag8SnS6, Ag8GeS6 and\nAg9GaS6 utilizing perturbation theory and the unified theory thermal transport\nmodel. Our results show that, as the complexity of the unit cell increases, the\nproportion of the population terms falls while the coherence contributions\nbecome more significant, leading to the relatively weak temperature-dependent\nkL of Ag7PS6 and Ag7AsS6, while the more complex crystalline argyrodites,\nAg8SnS6, Ag8GeS6 and Ag9GaS6, exhibiting a glass-like behavior in their\ntemperature dependence of kL. We attribute the positive temperature-dependent\nand ultralow kL of Ag8SnS6, Ag8GeS6 and Ag9GaS6 to the dominance of wavelike\nphonons and the strong phonon broadening. Furthermore, using laser flash\nmeasurements and the homogeneous non-equilibrium molecular dynamics simulations\nbased on accurate machine learning neuroevolution potentials, we provide\nfurther evidence for the glass-like temperature-dependent kL of Ag8SnS6 and\nAg8GeS6.",
        "positive": "Magnetic-field enhanced high-thermoelectric performance in topological\n  Dirac semimetal Cd$_3$As$_2$ crystal: Thermoelectric materials can be used to convert heat to electric power\nthrough the Seebeck effect. We study magneto-thermoelectric figure of merit\n(ZT) in three-dimensional Dirac semimetal Cd$_3$As$_2$ crystal. It is found\nthat enhancement of power factor and reduction of thermal conductivity can be\nrealized at the same time through magnetic field although magnetoresistivity is\ngreatly increased. ZT can be highly enhanced from 0.17 to 1.1 by more than six\ntimes around 350 K under a perpendicular magnetic field of 7 Tesla. The huge\nenhancement of ZT by magnetic field arises from the linear Dirac band with\nlarge Fermi velocity and the large electric thermal conductivity in\nCd$_3$As$_2$. Our work paves a new way to greatly enhance the thermoelectric\nperformance in the quantum topological materials."
    },
    {
        "anchor": "Universal amorphous-amorphous transition in GexSe1-x glasses under\n  pressure: Pressure induced structural modifications in vitreous Ge$_{x}$Se$_{100-x}$\n(where 10 $\\leq$ x $\\leq$ 25)are investigated using X-ray absorption\nspectroscopy (XAS) along with supplementary X-ray diffraction (XRD) experiments\nand ab initio molecular dynamics (AIMD) simulations. Universal changes in\ndistances and angle distributions are observed when scaled to reduced\ndensities. All compositions are observed to remain amorphous under pressure\nvalues up to 42 GPa. The Ge-Se interatomic distances extracted from XAS data\nshow a two-step response to the applied pressure; a gradual decrease followed\nby an increase at around 15-20 GPa, depending on the composition. This increase\nis attributed to the metallization event that can be traced with the red shift\nin Ge K edge energy which is also identified by the principal peak position of\nthe structure factor. The densification mechanisms are studied in details by\nmeans of AIMD simulations and compared to the experimental results. The\nevolution of bond angle distributions, interatomic distances and coordination\nnumbers are examined and lead to similar pressure-induced structural changes\nfor any composition.",
        "positive": "Two-Dimensional Scandium Carbide Monolayer and its Nanotubes: A two-dimensional scandium carbide monolayer with a Sc3C10 primitive cell\n(Sc3C10 sheet) has been identified using first-principles density functional\ntheory. In the Sc3C10 sheet, there is a similar basic structure to the one in\nthe Volleyballene Sc20C60, the Sc8C10 subunit, in which two connected carbon\npentagons are surrounded by one scandium octagon. The hybridization between Sc\nd orbitals and C s-p orbitals is crucial for stabilizing the Sc3C10 sheet. Ab\ninitio molecular dynamics simulations demonstrate that this Sc3C10 sheet is\nexceptionally stable. In addition, a series of stable ScC nanotubes have been\nobtained by rolling up this Sc3C10 sheet. All nanotubes studied have been found\nto be metallic."
    },
    {
        "anchor": "A first-principles characterization of the structure and electronic\n  structure of $\u03b1$-S and Rh-S chalcogenides: We have used first-principles calculations to study the structural,\nelectronic, and thermodynamic properties of the three known forms of Rh-S\nchalcogenides: Rh$_2$S$_3$, Rh$_3$S$_4$, and Rh$_{17}$S$_{15}$. Only the first\nof these materials of interest for catalysis had been studied previously within\nthis approach. We find that Rh$_{17}$S$_{15}$ crystallizes in a {\\em\nPm}\\={3}{\\em m} centrosymmetric structure, as believed experimentally but never\nconfirmed. We show band structures and densities of states for these compounds.\nFinally, we also investigated the ground state structure of solid sulfur\n($\\alpha$-S), one of the few elements that represents a challenge for full\nfirst-principles calculations due to its demanding 128-atom unit cell and\ndispersion interactionis between S$_8$ units.",
        "positive": "Electronic structure and magnetic properties of Gd-doped and Eu-rich EuO: The effects of Gd doping and O vacancies on the magnetic interaction and\nCurie temperature of EuO are studied using first-principles calculations.\nLinear response calculations in the virtual crystal approximation show a broad\nmaximum in the Curie temperature as a function of doping, which results from\nthe combination of the saturating contribution from indirect exchange and a\ndecreasing contribution from the f-d hopping mechanism. Non-Heisenberg\ninteraction at low doping levels and its effect on the Curie temperature are\nexamined. The electronic structure of a substitutional Gd and of an O vacancy\nin EuO are evaluated. When the 4f spins are disordered, the impurity state goes\nfrom single to double occupation, but correlated bound magnetic polarons are\nnot ruled out. At higher vacancy concentrations typical for Eu-rich EuO films,\nthe impurity states broaden into bands and remain partially filled. To go\nbeyond the homogeneous doping picture, magnetostructural cluster expansions are\nconstructed, which describe the modified exchange parameters near Gd dopants or\nO vacancies. Thermodynamic properties are studied using Monte Carlo\nsimulations. The Curie temperature for Gd-doped EuO agrees with the results of\nthe virtual crystal approximation and shows a maximum of about 150 K. At 3.125%\nvacancy concentration the Curie temperature increases to 120 K, consistent with\nexperimental data for Eu-rich film samples."
    },
    {
        "anchor": "Composition Patterning in Systems Driven by Competing Dynamics: We study an alloy system where short-ranged, thermally-driven diffusion\ncompetes with externally imposed, finite-ranged, athermal atomic exchanges, as\nis the case in alloys under irradiation. Using a Cahn-Hilliard-type approach,\nwe show that when the range of these exchanges exceeds a critical value,\nlabyrinthine concentration patterns at a mesoscopic scale can be stabilized.\nFurthermore, these steady-state patterns appear only for a window of the\nfrequency of forced exchanges. Our results suggest that ion beams may provide a\nnovel route to stabilize and tune the size of nanoscale structural features in\nmaterials.",
        "positive": "Quantitative characterization of surface topography using spectral\n  analysis: Roughness determines many functional properties of surfaces, such as\nadhesion, friction, and (thermal and electrical) contact conductance. Recent\nanalytical models and simulations enable quantitative prediction of these\nproperties from knowledge of the power spectral density (PSD) of the surface\ntopography. The utility of the PSD is that it contains statistical information\nthat is unbiased by the particular scan size and pixel resolution chosen by the\nresearcher. In this article, we first review the mathematical definition of the\nPSD, including the one- and two-dimensional cases, and common variations of\neach. We then discuss strategies for reconstructing an accurate PSD of a\nsurface using topography measurements at different size scales. Finally, we\ndiscuss detecting and mitigating artifacts at the smallest scales, and\ncomputing upper/lower bounds on functional properties obtained from models. We\naccompany our discussion with virtual measurements on computer-generated\nsurfaces. This discussion summarizes how to analyze topography measurements to\nreconstruct a reliable PSD. Analytical models demonstrate the potential for\ntuning functional properties by rationally tailoring surface topography -\nhowever, this potential can only be achieved through the accurate, quantitative\nreconstruction of the power spectral density of real-world surfaces."
    },
    {
        "anchor": "Decouple Electronic and Phononic Transport in Nanotwinned Structure: A\n  New Strategy for Enhancing the Figure-of-merit of Thermoelectrics: Thermoelectrics (TE) materials manifest themselves in direct conversion of\ntemperature differences to electric power and vice versa. Despite remarkable\nadvances have been achieved in the past decades for various TE systems, the\nenergy conversion efficiencies of TE devices, which is characterized by a\ndimensionless figure-of-merit (ZT ), remain a generally poor factor that\nseverely limits their competitiveness and range of employment. The bottleneck\nfor substantially boosting ZT coefficient lies in the strong interdependence of\nthe physical parameters involved in electronic and phononic transport. Here, we\npropose a new strategy of incorporating nanotwinned structures to decouple the\nelectronic and phononic transport. Combining the new concept of nanotwin with\nthe previously widely used nanocrystalline approach, the power factor of the Si\nnanotwin-nanocrystalline heterostructures is enhanced by 120% compared to bulk\ncrystalline Si, while the lattice thermal conductivity is reduced to a level\nwell below the amorphous limit, yielding a theoretical limit of 0.43 for ZT\ncoefficient at room temperature. This value is almost two orders of magnitude\nlarger than that for bulk Si and twice of the polycrystalline Si. Even for the\nexperimentally existing nanotwin-nanocrystalline heterostructures (e.g. grain\nsize of 5 nm), the ZT coefficient can be as high as 0.2 at room temperature,\nwhich is the highest ZT value among all the Si based bulk nanostructures so\nfar. Such substantial improvement stems from two aspects: (1) the improvement\nof the power factor is caused by the increase of Seebeck coefficient\n(degeneracy of the band valley) and the enhancement of electrical conductivity\n(the reduction of the effective band mass); (2) the significant reduction of\nthe lattice thermal conductivity is mainly caused by the extremely strong\nphonon-grain boundary and phonon-twin boundary scattering.",
        "positive": "Predicting colloidal crystals from shapes via inverse design and machine\n  learning: A fundamental challenge in materials design is linking building block\nattributes to crystal structure. Addressing this challenge is particularly\ndifficult for systems that exhibit emergent order, such as entropy-stabilized\ncolloidal crystals. We combine recently developed techniques in inverse design\nwith machine learning to construct a model that correctly classifies the\ncrystals of more than ten thousand polyhedral shapes into 13 different\nstructures with a predictive accuracy of 96% using only two geometric shape\nmeasures. With three measures, 98% accuracy is achieved. We test our model on\npreviously reported colloidal crystal structures for 71 symmetric polyhedra and\nobtain 92% accuracy. Our findings (1) demonstrate that entropic colloidal\ncrystals are controlled by surprisingly few parameters, (2) provide a\nquantitative model to predict these crystals solely from the geometry of their\nbuilding blocks, and (3) suggest a prediction paradigm that easily generalizes\nto other self-assembled materials."
    },
    {
        "anchor": "X-ray study of structural domains in the near-surface region of\n  SrTiO3-substrates with Y0.6Pr0.4Ba2Cu3O7$ / La2/3Ca1/3MnO3 superlattices\n  grown on top: We investigated with synchrotron x-ray diffraction and reflectometry the\nformation of structural domains in the near-surface region of single\ncrystalline SrTiO3 (001) substrates with Y0.6Pr0.4Ba2Cu3O7 / La2/3Ca1/3MnO3\nsuperlattices grown on top. We find that the antiferrodistortive\ncubic-to-tetragonal transition, which occurs at T_STO = 104K in the bulk and at\na considerably higher temperature of at least 120K in the surface region of\nSrTiO3, has only a weak influence on the domain formation. The strongest\nchanges occur instead in the vicinitiy of the tetragonal-to-orthorhombic\ntransition in SrTiO3 around 65K, where pronounced surface facets develop that\nreach deep (at least several micrometers) into the SrTiO3 substrate. These\nmicrometer-sized facets are anisotropic and tilted with respect to one another\nby up to 0.5deg along the shorter direction. Finally, we find that a third\nstructural transition below 30K gives rise to significant changes in the spread\nof the c-axis parameters. Overall, our data provide evidence for a strong\nmutual interaction between the stuctural properties of the SrTiO3 surface and\nthe multilayer grown on top.",
        "positive": "Strain-engineered A-type antiferromagnetic order in YTiO$_3$: a\n  first-principles calculation: The epitaxial strain effects on the magnetic ground state of YTiO$_3$ films\ngrown on LaAlO$_3$ substrates have been studied using the first-principles\ndensity-functional theory. With the in-plane compressive strain induced by\nLaAlO$_3$ (001) substrate, A-type antiferromagnetic order emerges against the\noriginal ferromagnetic order. This phase transition from ferromagnet to A-type\nantiferromagnet in YTiO$_3$ film is robust since the energy gain is about 7.64\nmeV per formula unit despite the Hubbard interaction and modest lattice\nchanges, even though the A-type antiferromagnetic order does not exist in any\n$R$TiO$_3$ bulks."
    },
    {
        "anchor": "General solution for quantitative dark-field contrast imaging with\n  grating interferometers: Dark-field contrast imaging with grating interferometers has proven to hold\nhuge potential for numerous applications with X-rays and with neutrons\nconveying biology and medicine as well as engineering and magnetism,\nrespectively. However, a concept to extract quantitative information is still\nmissing. Here a general theory as well as a measurement strategy is introduced,\nallowing extraction of quantitative small-angle scattering information such as\nstructure sizes and scattering cross sections. The validity of the description\nis demonstrated by a specific example from literature.",
        "positive": "Microscopic Aspects of Magnetic Lattice Demagnetizing Factors: The demagnetizing factor N is of both conceptual interest and practical\nimportance. Considering localized magnetic moments on a lattice, we show that\nfor non-ellipsoidal samples, N depends on the spin dimensionality (Ising, XY,\nor Heisenberg) and orientation, as well as the sample shape and susceptibility.\nThe generality of this result is demonstrated by means of a recursive analytic\ncalculation as well as detailed Monte Carlo simulations of realistic model spin\nHamiltonians. As an important check and application, we also make an accurate\nexperimental determination of N for a representative collective paramagnet\n(i.e. the Dy2Ti2O7 spin ice compound) and show that the temperature dependence\nof the experimentally determined N agrees closely with our theoretical\ncalculations. Our conclusion is that the well established practice of\napproximating the true sample shape with \"corresponding ellipsoids\" for systems\nwith long-range interactions will in many cases overlook important effects\nstemming from the microscopic aspects of the system under consideration."
    },
    {
        "anchor": "A simple, static and stage mounted direct electron detector based\n  electron backscatter diffraction system: To engineer the next generation of advanced materials we must understand\ntheir microstructure, and this requires microstructural characterization. This\ncan be achieved through the collection of high contrast, data rich, and\ninsightful microstructural maps. Electron backscatter diffraction (EBSD) has\nemerged as a popular tool available within the scanning electron microscope\n(SEM), where maps are realized through the repeat capture and analysis of\nKikuchi diffraction patterns. Typical commercial EBSD systems require large and\nsophisticated detectors that are mounted on the side of the SEM vacuum chamber\nwhich can be limiting in terms of widespread access to the technique. In this\nwork, we present an alternative open-hardware solution based upon a compact\nEBSD system with a simple, static geometry that uses an off-the-shelf direct\nelectron detector co-mounted with a sample. This simple stage is easy to\nmanufacture and improves our knowledge of the diffraction geometry\nsignificantly. Microscope and detector control is achieved through software\napplication programming interface (API) integration. After pattern capture,\nanalysis of the diffraction patterns is performed using open-source analysis\nwithin AstroEBSD. To demonstrate the potential of this set up, we present two\nsimple EBSD experiments using line scan and mapping. We hope that the present\nsystem can inspire simpler EBSD system design for widespread access to the EBSD\ntechnique and promote the use of open-source software and hardware in the\nworkflow of EBSD experiments.",
        "positive": "Potential energy surface prediction of Alumina polymorphs using graph\n  neural network: The process of design and discovery of new materials can be significantly\nexpedited and simplified if we can learn effectively from available data. Deep\nlearning (DL) approaches have recently received a lot of interest for their\nability to speed up the design of novel materials by predicting material\nproperties with precision close to experiments and ab-initio calculations. The\napplication of deep learning to predict materials properties measured by\nexperiments are valuable yet challenging due to the limited amount of\nexperimental data. Most of the existing approaches to predict properties from\ncomputational data have also been directed towards specific material\nproperties. In this work, we extend this approach, by proposing Landscape\nCrystal Graph Convolution Network(LCGCN), an accurate and transferable deep\nlearning framework based on graph convolutional networks. LCGCN directly learns\nthe potential energy surface (PES) from atomic configurations. This approach\ncan enable transferable models that can predict different material properties.\nWe apply this framework to bulk crystals (i.e. Al2O3), and test it by\ncalculating potential energy surfaces at different temperatures and across\ndifferent phases of crystal."
    },
    {
        "anchor": "Wedge disclination description of emergent core-shifted grain boundaries\n  at free surfaces: Emergent grain boundaries at free surface control material properties such as\nnanomaterial strength, catalysis, and corrosion. Recently the restructuring of\nemergent boundaries on copper (111) surfaces was discovered experimentally and\natomic calculations point to its universality in fcc metal systems.\nRestructuring is due to a preference for boundaries to shift their tilt axis\nacross the (1-10) plane towards [112] and ultimately to form low energy [112]\ncore shifted boundaries (CSBs). However, the observed geometry of these\nemergent boundaries is not reproduced by atomic calculations and the driving\nforce is still controversial due to inconsistencies between the computational\ncontinuum analysis and atomic calculations. Here, using atomic calculations\nthat involve a methodical shift of the dislocation core, we confirmed the core\nshift of emergent boundaries observed in experiment and reconciled the atomic\ncalculations with the elastic analysis through the inclusion of a straight\nwedge disclination at the free surface.",
        "positive": "Multilayer Silicene: a clear evidence: One year after the publication of the seminal paper on monolayer 3 by 3\nreconstructed silicene grown on a silver (111) substrate, evidence of the\nsynthesis of epitaxial root3 by root3 reconstructed multilayer silicene hosting\nDirac fermions was presented. Although a general consensus was immediately\nreached in the former case, in the latter one, the mere existence of multilayer\nsilicene was questioned and strongly debated. Here, we demonstrate by means of\na comprehensive x-ray crystallographic study, that multilayer silicene is\neffectively realized upon growth at rather low growth temperatures\n(~200{\\deg}C), while, instead, 3D growth of silicon crystallites takes place at\nhigher temperatures, (~300{\\deg}C). This transition to bulk like silicon\nperfectly explains the various data presented and discussed in the literature\nand solves their conflicting interpretations."
    },
    {
        "anchor": "Field induced long-range-ordering in an S=1 quasi-one-dimensional\n  Heisenberg antiferromagnet: We have measured the heat capacity and magnetization of the spin one\none-dimensional Heisenberg antiferromagnet NDMAP and constructed a magnetic\nfield versus temperature phase diagram. We found a field induced long-range\nmagnetic ordering. We have been successful in explaining the phase diagram\ntheoretically.",
        "positive": "Optical Visualization of Radiative Recombination at Partial Dislocations\n  in GaAs: Individual dislocations in an ultra-pure GaAs epilayer are investigated with\nspatially and spectrally resolved photoluminescence imaging at 5~K. We find\nthat some dislocations act as strong non-radiative recombination centers, while\nothers are efficient radiative recombination centers. We characterize\nluminescence bands in GaAs due to dislocations, stacking faults, and pairs of\nstacking faults. These results indicate that low-temperature,\nspatially-resolved photoluminescence imaging can be a powerful tool for\nidentifying luminescence bands of extended defects. This mapping could then be\nused to identify extended defects in other GaAs samples solely based on\nlow-temperature photoluminescence spectra."
    },
    {
        "anchor": "Hydrogen Atoms on Zigzag Graphene Nanoribbons: Chemistry and Magnetism\n  Meet at the Edge: Although the unconventional $\\pi$-magnetism at the zigzag edges of graphene\nholds promise for a wide array of applications, whether and to what degree it\nplays a role in their chemistry remains poorly understood. Here, we investigate\nthe addition of a hydrogen atom $-$ the simplest yet the most experimentally\nrelevant adsorbate $-$ to zigzag graphene nanoribbons (ZGNRs). We show that the\n$\\pi$-magnetism governs the chemistry of ZGNRs, giving rise to a site-dependent\nreactivity of the carbon atoms and driving the hydrogenation process to the\nnanoribbon edges. Conversely, the chemisorbed hydrogen atom governs the\n$\\pi$-magnetism of ZGNRs, acting as a spin-$\\frac{1}{2}$ paramagnetic center in\nthe otherwise antiferromagnetic ground state and spin-polarizing the charge\ncarriers at the band extrema. Our findings establish a comprehensive picture of\nthe peculiar interplay between chemistry and magnetism that emerges at the\nzigzag edges of graphene.",
        "positive": "Anisotropic Gigahertz Antiferromagnetic Resonances of the Easy-Axis van\n  der Waals Antiferromagnet CrSBr: We report measurements of antiferromagnetic resonances in the van der Waals\neasy-axis antiferromagnet CrSBr. The interlayer exchange field and\nmagnetocrystalline anisotropy fields are comparable to laboratory magnetic\nfields, allowing a rich variety of gigahertz-frequency dynamical modes to be\naccessed. By mapping the resonance frequencies as a function of the magnitude\nand angle of applied magnetic field we identify the different regimes of\nantiferromagnetic dynamics. The spectra show good agreement with a\nLandau-Lifshitz model for two antiferromagnetically-coupled sublattices,\naccounting for inter-layer exchange and triaxial magnetic anisotropy. Fits\nallow us to quantify the parameters governing the magnetic dynamics: at 5 K,\nthe interlayer exchange field is $\\mu_0 H_E =$ 0.395(2) T, and the hard and\nintermediate-axis anisotropy parameters are $\\mu_0 H_c =$ 1.30(2) T and $\\mu_0\nH_a =$ 0.383(7) T. The existence of within-plane anisotropy makes it possible\nto control the degree of hybridization between the antiferromagnetic resonances\nusing an in-plane magnetic field."
    },
    {
        "anchor": "Application of the Tool--Narayanaswamy--Moynihan model to the study of\n  the alpha relaxation by thermally stimulated depolarization currents: The dielectric alpha relaxation is the dielectric manifestation of the glass\ntransition. In spite of this fact, the more commonly used models, the Arrhenius\nmodel and the Williams--Landel--Ferry model, do not take into account the\nstructural state of the system to modelize this relaxation. In thermally\nstimulated discharge current (TSDC) experiments, the sample is out of\nequilibrium during most of the discharge ramp. Not surprisingly, the capability\nof these models to represent the data points at temperatures well below the\nglass transition temperature is very poor. To overcome this limitation, we have\nused the Tool--Narayanaswamy-Moynihan (TNM) model, that takes into account the\nstructural state of the system, to modelize TSDC data. Although it is mostly\napplied to calorimetric and volumetric experiments we show how it can be\nemployed on dielectric data. The numerical results support the applicability of\nthe model and suggest how the dielectric and the structural relaxation times\nmay be related. The TNM model turns out to be physically sound since the\nmodelization of dielectric data gives also a reasonable structural kinetics of\nthe system. The qualitative differences between the TNM model and the\nequilibrium models for different TSDC experiments is discussed. Experimental\ndata coming from TSDC experiments where the thermal history of the sample is\nchanged do not provide additional evidence but nevertheless are compatible with\nthe parameter values that were obtained in the fits to the TNM model.",
        "positive": "Interaction between concentric Tubes in DWCNTs: A detailed investigation of the Raman response of the inner tube radial\nbreathing modes (RBMs) in double-wall carbon nanotubes is reported. It revealed\nthat the number of observed RBMs is two to three times larger than the number\nof possible tubes in the studied frequency range. This unexpected increase in\nRaman lines is attributed to a splitting of the inner tube response. It is\nshown to originate from the possibility that one type of inner tube may form in\ndifferent types of outer tubes and the fact that the inner tube RBM frequency\ndepends on the diameter of the enclosing tube. Finally, a comparison of the\ninner tube RBMs and the RBMs of tubes in bundles gave clear evidence that the\ninteraction in a bundle is stronger than the interaction between inner and\nouter tubes."
    },
    {
        "anchor": "Insight into Two-Dimensional Borophene: Five-Center Bond and\n  Phonon-Mediated Superconductivity: We report a previously unknown monolayer borophene allotrope and we call it\nsuper-B with a flat structure based on the ab initio calculations. It has good\nthermal, dynamical, and mechanical stability compared with many other typical\nborophenes. We find that super-B has a fascinating chemical bond environment\nconsisting of standard sp, sp2 hybridizations, and delocalized five-center\nthree-electron $\\pi$ bond, called $\\pi$(5c-3e). This particular electronic\nstructure plays a pivotal role in stabilizing the super-B chemically. By extra\ndoping, super-B can be transformed into a Dirac material from pristine metal.\nLike graphene, it can also sustain tensile strain smaller than 24%, indicating\nsuperior flexibility. Moreover, due to the small atomic mass and large density\nof states at the Fermi level, super-B has the highest critical temperature Tc\nof 25.3 K in single-element superconductors at ambient conditions. We attribute\nthis high Tc of super-B to the giant anharmonicity of two linear acoustic\nphonon branches and an unusually low optic phonon mode. These predictions\nprovide new insight into the chemical nature of low dimensional boron\nnanostructures and highlight the potential applications of designing flexible\ndevices and high Tc superconductors.",
        "positive": "Influence of Mutual Drag of Light and Heavy Holes on conductivity of\n  p-Silicon and p-Germanium: Conductivity of p-Si and p-Ge is considered for two band model with due\nregard for mutual drag of light and heavy holes. It is shown that for small and\nmoderate temperatures this drag significantly diminishes drift velocity of\nlight holes and, as result, the total conductivity of crystal. Considered here\ndrag-effect appears as well in the form of nonmonotonous dependences of\nconductivity on temperature and carrier density."
    },
    {
        "anchor": "Ab initio study of ferromagnetism induced by magnetic impurities in\n  rutile TiO2: Using the first-principles density-functional approach, magnetic properties\nof Mn-, Fe-, Co-, and Ni-doped rutile TiO2 were investigated for two different\nimpurity concentrations (25% and 6.25%). Calculations were performed with the\nFull-Potential Linearized-Augmented Plane Waves (FLAPW) method, assuming that\nthe magnetic impurities substitutionally replace the Ti ions. Our results show\nthat the systems (with the exception of Ni-doped TiO2) are ferromagnetic. We\nalso found that polarization mainly occurs at the impurity sites, and the\nmagnetic moments of the impurities are independent of the impurity\nconcentration.",
        "positive": "High-Performance Thermoelectric Oxides Based on Spinel Structure: High-performance thermoelectric oxides could offer a great energy solution\nfor integrated and embedded applications in sensing and electronics industries.\nOxides, however, often suffer from low Seebeck coefficient when compared with\nother classes of thermoelectric materials. In search of high-performance\nthermoelectric oxides, we present a comprehensive density functional\ninvestigation, based on GGA$+U$ formalism, surveying the 3d and 4d\ntransition-metal-containing ferrites of the spinel structure. Consequently, we\npredict MnFe$_2$O$_4$ and RhFe$_2$O$_4$ have Seebeck coefficients of $\\sim \\pm\n600$ $\\mu$V K$^{-1}$ at near room temperature, achieved by light hole and\nelectron doping. Furthermore, CrFe$_2$O$_4$ and MoFe$_2$O$_4$ have even higher\nambient Seebeck coefficients at $\\sim \\pm 700$ $\\mu$V K$^{-1}$. In the latter\ncompounds, the Seebeck coefficient is approximately a flat function of\ntemperature up to $\\sim 700$ K, offering a tremendous operational convenience.\nAdditionally, MoFe$_2$O$_4$ doped with $10^{19}$ holes/cm$^3$ has a calculated\nthermoelectric power factor of $689.81$ $\\mu$W K$^{-2}$ m$^{-1}$ at $300$ K,\nand $455.67$ $\\mu$W K$^{-2}$ m$^{-1}$ at $600$ K. The thermoelectric properties\npredicted here can bring these thermoelectric oxides to applications at lower\ntemperatures traditionally fulfilled by more toxic and otherwise burdensome\nmaterials."
    },
    {
        "anchor": "The role of low-energy phonons with mean-free-paths >0.8 um in heat\n  conduction in silicon: Despite recent progress in the first-principles calculations and measurements\nof phonon mean-free-paths (MFPs), contribution of low-energy phonons to heat\nconduction in silicon is still inconclusive, as exemplified by the\ndiscrepancies between different first-principles calculations. Here we\ninvestigate the contribution of low-energy phonons with MFP>0.8 um by\naccurately measuring the cross-plane thermal conductivity of crystalline\nsilicon films by time-domain thermoreflectance (TDTR), over a wide range of\nfilm thickness 1-10 um and temperature 100-300 K. We employ a dual-frequency\nTDTR approach to improve the accuracy of our cross-plane thermal conductivity\nmeasurements. We find from our cross-plane thermal conductivity measurements\nthat phonons with MFP>0.8 um contribute 53 W/m-K (37%) to heat conduction in Si\nat 300 K while phonons with MFP>3 um contribute 523 W/m-K (61%) at 100 K, >20%\nlower than the first-principles predictions by Lindsay et al. of 68 W/m-K (47%)\nand 695 W/m-K (77%), respectively. Using a relaxation times approximation (RTA)\nmodel, we demonstrate that macroscopic damping (e.g., Akhieser's damping)\neliminates the contribution of phonons with mean-free-paths >30 um at 300 K,\nwhich contributes 15 W/m-K (10%) to heat conduction in Si according to Lindsay\net al. Thus we propose that omission of the macroscopic damping for low-energy\nphonons in the first-principles calculations could be one of the possible\nexplanations for the observed discrepancy between our measurements and\ncalculations by Lindsay et al. Our work provides an important benchmark for\nfuture measurements and calculations of the distribution of phonon\nmean-free-paths in crystalline silicon.",
        "positive": "Coexistence of multiple metastable polytypes in rhombohedral bismuth: Derivative structural polytypes coexisting with the rhombohedral A7 structure\nof elemental bismuth (Bi) have been discovered at ambient condition, based on\nmicrostructure analyses of pure Bi samples treated under high pressure and high\ntemperature conditions. Three structures with atomic positions close to those\nof the A7 structure have been identified through first-principles calculations,\nshowing these polytypes energetically comparable to the A7 structure under\nambient condition. Simulated diffraction data are in excellent agreement with\nthe experimental observations. We argue that previously reported variations in\nphysical properties (e.g., density, melting point, electrical conductivity, and\nmagnetism) in bismuth could be due to the formation of these polytypes. The\ncoexistence of metastable derivative structural polytypes may be a widely\noccurring phenomenon in other elemental materials"
    },
    {
        "anchor": "Emergence of current branches in a series array of negative differential\n  resistance circuit elements: We study a series array of nonlinear electrical circuit elements that possess\nnegative differential resistance and find that \\emph{heterogeneity} in the\nelement properties leads to the presence of multiple branches in\ncurrent-voltage curves and a non-uniform distribution of voltages across the\nelements. An inhomogeneity parameter $r_{max}$ is introduced to characterize\nthe extent to which the individual element voltages deviate from one another,\nand it is found to be strongly dependent on the rate of change of applied\nvoltage. Analytical expressions are derived for the dependence of $r_{max}$ on\nvoltage ramping rate in the limit of fast ramping and are confirmed by direct\nnumerical simulation.",
        "positive": "Impact of cation redox chemistry on continuous hydrothermal synthesis of\n  2D-Ni(Co/Fe) hydroxides: Continuous hydrothermal flow synthesis (CHFS) is a facile, upscalable and\ncost-efficient synthetic method enabling the nanostructuring of advanced\nfunctional materials in steady conditions, i.e. not in batch synthesis. In this\npaper, we use CHFS to crystallize NiCo- and NiFe-hydroxides in water solution\nwith 2D nanofeatures. By tuning the synthetic parameters, we disclose the key\nrole of the cation redox chemistry in the transition between two competitive\nphases: from 2D-nanoplatelets of brucite to layered double hydroxides (LDH).\nFor controlling the precipitation of different Ni, Fe, Co-hydroxide phases, we\npropose the combined use of an oxidizing (H2O2) and a complexing (NH3) agent.\nAt temperatures as low as 80 {\\deg}C, the presence of H2O2 and a low\nconcentration of NH3 favour the Ni2+/Co3+ over Ni2+/Co2+ oxidation states,\nshifting the product structure from brucite phase (temperatures > 80 {\\deg}C)\nto LDH. Conversely, for the NiFe-hydroxides the transition from LDH\n(temperatures < 80 {\\deg}C) to brucite phase (temperatures > 80 {\\deg}C) is\ncontrolled by the reaction temperature only. Due to the high stability of Fe3+,\nthe synthesis of NiFe products by CHFS does not require oxidizing and\ncomplexing agents, resulting in a robust process for large-scale production."
    },
    {
        "anchor": "Conduction Electron Spin-Flipping at Sputtered Co(90)Fe(10)/Cu\n  Interfaces: From measurements of the current-perpendicular-to-plane (CPP)\nmagnetoresistance of ferromagnetically coupled [Co(90)Fe(10)/Cu]xn multilayers,\nwithin sputtered Permalloy-based double exchange biased spin-valves, we\ndetermine the parameter delta[(Co(90)Fe(10))/Cu] = 0.19 +/- 0.04 that sets the\nprobability P of spin-flipping at a Co(90)Fe(10)/Cu interface via the equation\nP = 1 - exp(-delta).",
        "positive": "Imbibition in Disordered Media: The physics of liquids in porous media gives rise to many interesting\nphenomena, including imbibition where a viscous fluid displaces a less viscous\none. Here we discuss the theoretical and experimental progress made in recent\nyears in this field. The emphasis is on an interfacial description, akin to the\nfocus of a statistical physics approach. Coarse-grained equations of motion\nhave been recently presented in the literature. These contain terms that take\ninto account the pertinent features of imbibition: non-locality and the\nquenched noise that arises from the random environment, fluctuations of the\nfluid flow and capillary forces. The theoretical progress has highlighted the\npresence of intrinsic length-scales that invalidate scale invariance often\nassumed to be present in kinetic roughening processes such as that of a\ntwo-phase boundary in liquid penetration. Another important fact is that the\nmacroscopic fluid flow, the kinetic roughening properties, and the effective\nnoise in the problem are all coupled. Many possible deviations from simple\nscaling behaviour exist, and we outline the experimental evidence. Finally,\nprospects for further work, both theoretical and experimental, are discussed."
    },
    {
        "anchor": "Analysis of the Robustness of Conventional and Topologically Protected\n  Edge States in Phononic Crystal Plates: In this work we theoretically study the interface acoustic states of\nresonators on a thin plate with topologically protected and conventional\ndesigns. Topologically protected interface state is first analyzed by employing\nthe conception of breaking inversion symmetry within the unit cell of a\nhoneycomb lattice for cylindrical and spherical resonators; we further\ndemonstrate the robustness of the wave propagation along a zig-zag path\ncontaining sharp corners, defect and disorder. The wave propagation ceases to\nbe preserved if we increase the degree of disorder along the zig-zag path. In\nparallel, the conventional interface state is also designed and compared to the\nsame situations. We found that the conventional interface state suffers back\nscattering in the zig-zag path while it can show a more confined wave transport\nin some cases. The presence of a defect along the propagation path scatters the\nconventional interface wave and in particular can prohibit a full propagation\nin presence of a localized state at the defect. If the zig-zag path is made\ndisordered, the propagation of the conventional interface mode can be conserved\nat given frequencies for a low random degree and disappears for higher random\ndegree as the interface bands become flat in dispersion and turn to localized\nstates. Finally, we show that the immunity of the topologically protected\ndesign needs the interface to be surrounded by at least two hexagons of the\nphononic crystals on both sides, especially at the sharp corners in the zig-zag\npath, while the conventional design only needs one hexagon bulk media with the\nadvantage of compact wave transport. This work puts a step forward for the\ninterface states in micro-/nano-scale characterization and figures out the\nbehaviors for both topologically protected and conventional interface states.",
        "positive": "Topological Crystalline Insulators: The recent discovery of topological insulators has revived interest in the\ntopological properties of insulating band structures. In this work, we extend\nthe topological classification of insulating band structures to include certain\npoint group symmetry of crystals. We find a class of three-dimensional\n\"topological crystalline insulators\" which have metallic surface states on\ncertain high symmetry crystal surfaces. These topological crystalline\ninsulators can be viewed as the counterpart of topological insulators in\nmaterials without spin-orbit coupling. Their surface states have quadratic band\ndegeneracy instead of linear Dirac dispersion. Their band structures are\ncharacterized by new Z2 invariants. We hope this work will enlarge the family\nof topological phases in band insulators and stimulate the search for them in\nreal materials."
    },
    {
        "anchor": "Free-standing bialkali photocathodes using atomically thin substrates: We report successful deposition of high quantum efficiency (QE) bialkali\nantimonide K2CsSb photocathodes on graphene films. The results pave a pathway\ntowards an ultimate goal of encapsulating technologically-relevant\nphotocathodes for accelerator technology with an atomically-thin protecting\nlayer to enhance lifetime while minimizing QE losses. A QE of 17 % at ~3.1 eV\n(405 nm) is the highest value reported so far on graphene substrates and is\ncomparable to that obtained on stainless steel and nickel reference substrates.\nThe spectral responses of the photocathodes on graphene exhibit signature\nfeatures of K2CsSb including the characteristic absorption at ~2.5 eV.\nMaterials characterization based on X-ray fluorescence (XRF) and X-ray\ndiffraction (XRD) reveals that the composition and crystal quality of these\nphotocathodes deposited on graphene is comparable to those deposited on a\nreference substrate. Quantitative agreement between optical calculations and QE\nmeasurements for the K2CsSb on free suspended graphene and a graphene coated\nmetal substrate further confirms the high quality interface between the\nphotocathodes and graphene. Finally, a correlation between the QE and graphene\nquality as characterized by Raman spectroscopy suggests that a lower density of\natomistic defects in the graphene films leads to higher QE of the deposited\nK2CsSb photocathodes.",
        "positive": "Giant electron-phonon interactions in molecular crystals and the\n  importance of non-quadratic coupling: We investigate electron-phonon coupling in the molecular crystals CH$_4$,\nNH$_3$, H$_2$O, and HF, using first-principles quantum mechanical calculations.\nWe find vibrational corrections to the electronic band gaps at zero temperature\nof -1.97 eV, -1.01 eV, -1.52 eV, and -1.62 eV, respectively, which are\ncomparable in magnitude to those from electron-electron correlation effects.\nMicroscopically, the strong electron-phonon coupling arises in roughly equal\nmeasure from the almost dispersionless high-frequency molecular modes and from\nthe lower frequency lattice modes. We also highlight the limitations of the\nwidely used Allen-Heine-Cardona theory, which gives significant discrepancies\ncompared to our more accurate treatment."
    },
    {
        "anchor": "Thermal Hall effect in a van der Waals triangular magnet FeCl2: Thermal transport is a pivotal probe for studying low-energy, charge-neutral\nquasi-particles in insulating magnets. In this Letter, we report an observation\nof large magneto-thermal conductivity and thermal Hall effect (THE) in a van\nder Waals antiferromagnet FeCl2. The magneto-thermal conductivity reaches over\n~700%, indicating strong magnon-phonon coupling. Furthermore, we find an\nappreciable thermal Hall signal which changes sign concurrently with the\nspin-flip transition from the antiferromagnetic state to the polarized\nferromagnetic state. Our theoretical calculations suggest that, in addition to\nthe Berry curvature induced at the anticrossing points of the hybridized magnon\nand acoustic phonon modes of FeCl2, other mechanisms are needed to account for\nthe magnitude of the observed THE.",
        "positive": "Strain Engineering of Quantum Emitters in Hexagonal Boron Nitride: Quantum emitters in hexagonal boron nitride (hBN) are promising building\nblocks for the realization of integrated quantum photonic systems. However,\ntheir spectral inhomogeneity currently limits their potential applications.\nHere, we apply tensile strain to quantum emitters embedded in few-layer hBN\nfilms and realize both red and blue spectral shifts with tuning magnitudes up\nto 65 meV, a record for any two-dimensional quantum source. We demonstrate\nreversible tuning of the emission and related photophysical properties. We also\nobserve rotation of the optical dipole in response to strain, suggesting the\npresence of a second excited state. We derive a theoretical model to describe\nstrain-based tuning in hBN, and the rotation of the optical dipole. Our work\ndemonstrates the immense potential for strain tuning of quantum emitters in\nlayered materials to enable their employment in scalable quantum photonic\nnetworks."
    },
    {
        "anchor": "Switchable in-plane anomalous Hall effect by magnetization orientation\n  in monolayer $\\mathrm{Mn}_{3}\\mathrm{Si}_{2}\\mathrm{Te}_{6}$: In-plane anomalous Hall effect (IPAHE) is a unconventional anomalous Hall\neffect (AHE) with the Hall current flows in the plane spanned by the\nmagnetization or magnetic field and the electric field. Here, we predict a\nstable two-dimensional ferromagnetic monolayer\n$\\mathrm{Mn}_{3}\\mathrm{Si}_{2}\\mathrm{Te}_{6}$ with collinear ordering of Mn\nmoments in the basal plane. Moreover, we reveal that the monolayer\n$\\mathrm{Mn}_{3}\\mathrm{Si}_{2}\\mathrm{Te}_{6}$ possesses a substantial\nperiodic IPAHE due to the threefold rotational symmetry, which can be switched\nby changing the magnetization orientation by external magnetic fields. In\naddition, we briefly discuss the impacts of moderate strains on the electronic\nstates and AHE, which lead to a near quantized Hall conductivity. Our work\nprovides a potential platform for realizing a sizable and controllable IPAHE\nthat greatly facilatates the application of energy-efficient spintronic\ndevices.",
        "positive": "Thickness dependence of the resistivity of Platinum group metal thin\n  films: We report on the thin film resistivity of several platinum-group metals (Ru,\nPd, Ir, Pt). Platinum-group thin films show comparable or lower resistivities\nthan Cu for film thicknesses below about 5\\,nm due to a weaker thickness\ndependence of the resistivity. Based on experimentally determined mean linear\ndistances between grain boundaries as well as ab initio calculations of the\nelectron mean free path, the data for Ru, Ir, and Cu were modeled within the\nsemiclassical Mayadas--Shatzkes model [Phys. Rev. B 1, 1382 (1970)] to assess\nthe combined contributions of surface and grain boundary scattering to the\nresistivity. For Ru, the modeling results indicated that surface scattering was\nstrongly dependent on the surrounding material with nearly specular scattering\nat interfaces with SiO2 or air but with diffuse scattering at interfaces with\nTaN. The dependence of the thin film resistivity on the mean free path is also\ndiscussed within the Mayadas--Shatzkes model in consideration of the\nexperimental findings."
    },
    {
        "anchor": "Quantifying the effect of hydrogen on dislocation dynamics: A\n  three-dimensional discrete dislocation dynamics framework: We present a new framework to quantify the effect of hydrogen on dislocations\nusing large scale three-dimensional (3D) discrete dislocation dynamics (DDD)\nsimulations. In this model, the first order elastic interaction energy\nassociated with the hydrogen-induced volume change is accounted for. The\nthree-dimensional stress tensor induced by hydrogen concentration, which is in\nequilibrium with respect to the dislocation stress field, is derived using the\nEshelby inclusion model, while the hydrogen diffusion is treated as a continuum\nprocess. This newly developed framework is utilized to quantify the effect of\ndifferent hydrogen concentrations on the dynamics of a glide dislocation in the\nabsence of an applied stress field as well as on the spacing between\ndislocations in an array of parallel edge dislocations. A shielding effect is\nobserved for materials having a large hydrogen diffusion coefficient, with the\nshield effect leading to the homogenization of the shrinkage process leading to\nthe glide loop maintaining its circular shape, as well as resulting in a\ndecrease in dislocation separation distances in the array of parallel edge\ndislocations. On the other hand, for materials having a small hydrogen\ndiffusion coefficient, the high hydrogen concentrations around the edge\ncharacters of the dislocations act to pin them. Higher stresses are required to\nbe able to unpin the dislocations from the hydrogen clouds surrounding them.\nFinally, this new framework can open the door for further large scale studies\non the effect of hydrogen on the different aspects of dislocation-mediated\nplasticity in metals. With minor modifications of the current formulations, the\nframework can also be extended to account for general inclusion-induced stress\nfield in discrete dislocation dynamics simulations.",
        "positive": "Nano-thermodynamics of chemically induced graphene-diamond\n  transformation: Nearly two-dimensional diamond, or diamane, is coveted as ultrathin\n$sp^3$-carbon film with unique mechanics and electro-optics. The very thinness\n($~h$) makes it possible for the surface chemistry, e.g. adsorbed atoms, to\nshift the bulk phase thermodynamics in favor of diamond, from multilayer\ngraphene. Thermodynamic theory coupled with atomistic first principles\ncomputations predicts not only the reduction of required pressure\n($p/p_{\\infty}>1-h_0/h$), but also the nucleation barriers, definitive for the\nkinetic feasibility of diamane formation. Moreover, the optimal adsorbent\nchair-pattern on a bilayer graphene results in a cubic diamond lattice, while\nfor thicker precursors the adsorbent boat-structure tends to produce hexagonal\ndiamond (lonsdaleite), if graphene was in AA` stacking to start with. As\nadsorbents, H and F are conducive to diamond formation, while Cl appears\nsterically hindered."
    },
    {
        "anchor": "Multiferroic hexagonal ferrites (h-RFeO$_3$, R=Y, Dy-Lu): an\n  experimental review: Hexagonal ferrites (h-RFeO$_3$, R=Y, Dy-Lu) have recently been identified as\na new family of multiferroic complex oxides.\n  The coexisting spontaneous electric and magnetic polarizations make\nh-RFeO$_3$ rare-case ferroelectric ferromagnets at low temperature.\n  Plus the room-temperature multiferroicity and predicted magnetoelectric\neffect, h-RFeO$_3$ are promising materials for multiferroic applications.\n  Here we review the structural, ferroelectric, magnetic, and magnetoelectric\nproperties of h-RFeO$_3$.\n  The thin film growth is also discussed because it is critical in making high\nquality single crystalline materials for studying intrinsic properties.",
        "positive": "Electronic structure and photoluminescence properties of Zn-ion\n  implanted silica glass before and after thermal annealing: The results of XPS core-level and valence band measurements,\nphotoluminescence spectra of a-SiO2 implanted by Zn-ions (E=30 keV, D=1*1017\ncm^-2) and Density Functional Theory calculations of electronic structure as\nwell as formation energies of structural defects in silica glass induced by\nZn-ion implantation are presented. Both theory and experiment show that it is\nenergetically more favorable for implanted zinc ions to occupy the interstitial\npositions instead of cation substitution. As a result, the Zn-ions embedded to\ninterstitials, form chemical bonds with the surrounding oxygen atoms, formation\nZnO-like nanoparticles and oxygen-deficient SiOx matrix. The subsequent thermal\nannealing at 900 0C (1 hr) strongly reduces the amount of ZnO nanoparticles and\ninduces the formation of {\\alpha}-Zn2SiO4 phase which markedly enhances the\ngreen emission."
    },
    {
        "anchor": "Effect of homogenization on precipitation behavior and strengthening of\n  17-4PH stainless steel fabricated using laser powder bed fusion: Effective post-heat treatment is critical to achieve desired microstructure\nfor high-performance in additively manufactured (AM) components. In this work,\nthe influence of homogenization on microstructure-property relationship in\n17-4PH steels has been investigated. Precipitation of NbC, oxides, and\n{\\epsilon}-Cu were observed in the as-built 17-4PH steels. To design an optimum\npost-heat treatment, homogenization was performed at 1050oC for different times\nfollowed by aging at 482oC for 1 hour. It was identified that homogenization\nfor 1 hour followed by aging leads to the best combination of strength and\nductility due to the refinement of martensite and prior austenite grains.\nImproved tensile properties were achieved for the post-heat-treated alloys that\nexceeded the traditionally fabricated 17-4PH steels. Through comprehensive\nmicrostructure characterization, it was deduced that the incoherent\n{\\epsilon}-Cu precipitates in the as-built alloy were dissolved through\nhomogenization, and subsequently, re-precipitated as coherent Cu-rich clusters\nduring aging. This study demonstrates that altering the precipitation behavior\nusing post-heat treatment is an effective pathway to significantly improve the\nmechanical properties of AM alloys.",
        "positive": "Permanent-magnet-based transverse thermoelectric generator with high\n  fill factor driven by anomalous Nernst effect: A transverse thermoelectric generator for magnetic-field-free and\nhigh-density power generation utilizing the anomalous Nernst effect is\nconstructed and its performance is characterized. By alternately stacking two\ndifferent permanent magnets with the large coercivity and anomalous Nernst\ncoefficients of opposite sign, transverse thermoelectric voltage and power can\nbe generated in the absence of external magnetic fields and enhanced owing to a\nthermopile structure without useless electrode layers. In the\npermanent-magnet-based stack, the magnetic attractive force enables easy\nconstruction of the thermopile structure with a high fill factor. In this\nstudy, we construct a bulk module consisting of twelve pairs of SmCo$_5$- and\nNd$_2$Fe$_{14}$B-type permanent magnets with respectively having the positive\nand negative anomalous Nernst coefficients, whose fill factor reaches ~80%,\nwhereas that of conventional thermoelectric modules based on the Seebeck effect\nis typically 30-60%. We demonstrate magnetic-field-free anomalous Nernst power\ngeneration up to 177 $\\mu$W at a temperature difference of 75 K around room\ntemperature, which corresponds to the largest anomalous Nernst power density of\n65 $\\mu$W/cm$^2$. The presented module structure concept will provide a design\nguideline for high-performance transverse thermoelectric power generation."
    },
    {
        "anchor": "$d_{xz/yz}$ Orbital Subband Structures and Chiral Orbital Angular\n  Momentum in the (001) Surface States of SrTiO$_3$: We have performed angle resolved photoemission spectroscopy (ARPES)\nexperiments on the surface states of SrTiO$_3$(001) using linearly and\ncircularly polarized light to investigate the subband structures of\nout-of-plane $d_{xz/yz}$ orbitals and chiral orbital angular momentum (OAM).\nThe data taken in the first Brillouin zone reveal new subbands for $d_{xz/yz}$\norbitals with Fermi wave vectors of 0.25 and 0.45 $\\mathrm{\\AA}^{-1}$ in\naddition to the previously reported ones. As a result, there are at least two\nsubbands for all the Ti 3d t$_{2g}$ orbitals. Our circular dichroism ARPES data\nis suggestive of a chiral OAM structure in the surface states and may provide\nclues to the origin of the linear Rashba-like surface band splitting.",
        "positive": "Multiple transfer of angular momentum quanta from a spin-polarized hole\n  to magnetic ions in ZnMnSe/ZnBeSe quantum wells: The magnetization kinetics in (Zn,Mn)Se/(Zn,Be)Se quantum wells has been\nstudied on a ps-time scale after pulsed laser excitation. The magnetization\ninduced by an external magnetic field is reduced by up to 30% during ~100 ps\ndue to spin and energy transfer from photocarriers to Mn spin system. The giant\nZeeman splitting leads to a complete spin polarization of the carriers,\nresulting in a strong suppression of flip-flop processes between carriers and\nmagnetic ions. Therefore a multiple angular momentum transfer from each\nspin-polarized hole to the Mn ions becomes the dominant mechanism in the\nmagnetization dynamics. A model based on spin-momentum coupling in the valence\nband is suggested for explaining this transfer."
    },
    {
        "anchor": "Coordination motifs and large-scale structural organization in atomic\n  clusters: The structure of nanoclusters is complex to describe due to their\nnoncrystallinity, even though bonding and packing constraints limit the local\natomic arrangements to only a few types. A computational scheme is presented to\nextract coordination motifs from sample atomic configurations. The method is\nbased on a clustering analysis of multipole moments for atoms in the first\ncoodination shell. Its power to capture large-scale structural properties is\ndemonstrated by scanning through the ground state of the Lennard-Jones and\nC$_{60}$ clusters collected at the Cambridge Cluster Database.",
        "positive": "Copper alloys deterioration due to anthropogenic action: Results are presented from several samples taken from leaves of the Pardon\nPortico of Mosque-Cathedral of Cordoba, where an alteration on their surface\nwas detected. Metal samples analyzed using X-ray microanalysis and powder x-ray\ndiffraction were predominantly constituted by copper with some amounts of zinc\nattributed to brass, whereas other samples were also constituted by copper, tin\nand lead attributed to bronze. Surface samples were analyzed using the same\ntechniques. In addition Fourier transform infrared spectroscopy was also\nused.The main compound identified in all the surface of the leaves is copper\nchloride hydroxide (atacamite). Lead chlorides have also been found. These data\nshow that the sudden alteration that appears may be attributed to the use of\nsome cleaning product containing chloride. Other compounds detected in the\nsurface were gypsum, quartz and oxalates coming from environmental\ncontamination."
    },
    {
        "anchor": "Carrier dynamics in silicon nanowires studied via femtosecond transient\n  optical spectroscopy from 1.1 to 3.5 eV: We present femtosecond transient transmission (or absorbance) measurements in\nsilicon nanowires in the energy range 1.1-3.5 eV, from below the indirect\nband-gap to above the direct band-gap. Our pump-probe measurements allow us to\ngive a complete picture of the carrier dynamics in silicon. In this way we\nperform an experimental study with a spectral completeness that lacks in the\nwhole literature on carrier dynamics in silicon. A particular emphasis is given\nto the dynamics of the transient absorbance at the energies relative to the\ndirect band gap at 3.3 eV. Indeed, the use of pump energies below and above 3.3\neV allowed us to disentangle the dynamics of electrons and holes in their\nrespective bands. The band gap renormalization of the direct band gap is also\ninvestigated for different pump energies. A critical discussion is given on the\nresults below 3.3 eV where phonon-assisted processes are required in the\noptical transitions.",
        "positive": "Development of Si based anodes for Li-ion batteries from a rational\n  component design: Inspired by the wisdom of metallurgists in designing new alloys, the\nIntegrated Computational Materials Engineering (ICME) based design strategy is\nproposed for development of Si based anodes for Li-ion batteries (LIBs). The\nstrategy starts with a rational component design of Si-X, where X is the\nadditive component(s) helping to overcome the problems of the pure Si anodes.\nAn optimization of the composition, structure, property and performance of the\nSi-X anode is followed to fulfill the requirements for its commercialization.\nIn addition to the widely applied designing scheme for the nanostructured Si\nanodes, the presently proposed one from the ICME based rational component\ndesign is expected to accelerate the discovery of the promising Si based anodes\nfor commercial LIBs."
    },
    {
        "anchor": "A self-similar morphology detected in a composite produced by\n  densification of co-crumpled metallic thin foils: A new kind of composite were manufactured by densification of co-crumpled\naluminium and tantalum thin foils using close die compression. It was shown by\noptical micrography that its microstructure is highly interlocked. The\nmorphology was analysed quantitatively in terms of the following three\nparameters: the area of the foil interface per unit volume, the interface\ntortuosity, and a characteristic of the local orientation of the foil surface.\nBased on these parameters, co-crumpled material studied has been compared with\nconventional laminates. A fractal nature of its self-similar structure was\nrevealed.",
        "positive": "Pressure driven Weyl-topological insulator phase transition in Weyl\n  semimetal SrSi$_{2}$: Using DFT-based first-principles calculations, we demonstrate the tuning of\nthe electronic structure of Weyl semimetal SrSi$_{2}$ via external uniaxial\nstrain. The uniaxial strain facilitates the opening of bandgap along $\\Gamma$-X\ndirection and subsequent band inversion between Si $p$ and Sr $d$ orbitals.\nZ$_{2}$ invariants and surface states reveal conclusively that SrSi$_{2}$ under\nuniaxial strain is a strong topological insulator. Hence, uniaxial strain\ndrives the semimetallic SrSi$_{2}$ into fully gapped topological insulating\nstate depicting a semimetal to topological insulator phase transition. Our\nresults highlight the suitability of uniaxial strain to gain control over the\ntopological phase transitions and topological states in SrSi$_{2}$."
    },
    {
        "anchor": "Nitrogen doped In$_2$O$_3$-ZnO nanocomposite thin film based sensitive\n  and selective ethanol sensor: Nanocomposite metal oxide thin films exhibit assuring qualities in the field\nof gas sensors because of the collective opportunities provided by the\nheterointerface formation. In this work, we present the synthesis of nitrogen\ndoped mesoporous In$_2$O$_3$-ZnO nano-composite thin films by simple wet\nchemical method using urea as the nitrogen precursor. SEM investigation\nsuggests formation of mesoporous nano-composite thin films, where the\nuniformity of surface pore distribution depends on the relative proportion of\nIn$_2$O$_3$ and ZnO in the composites. HRTEM investigation suggest formation of\nsharp interfaces between N-In$_2$O$_3$ and N-ZnO grains in the nano-composite\nthin films. The nano-composite thin films have been tested for their ethanol\nsensing performance over an extensive range of temperature, ethanol vapor\nconcentration and relative humidity. Nitrogen doped nano-composite thin film\nwith equal proportion of In$_2$O$_3$ and ZnO exhibits excellent ethanol sensing\nperformance at a reasonable operating temperature (~94 % at 200 {\\deg}C for 50\nppm of ethanol), fast response time (~two seconds), stability over time,\nenhanced resilience against humidity and selectivity to ethanol over various\nother volatile organic compounds.",
        "positive": "Ab initio electronic and geometrical structures of\n  tripotassium-intercalated phenanthrene: The geometrical and electronic structure of tripotassium doped phenanthrene,\n\\ce{K3C14H10}, have been studied by first-principles density functional theory.\nThe main effect of potassium doping is to inject charge in the narrow\nphenanthrene conduction band, rendering the system metallic. The Fermi surface\nfor the experimental X-rays unit cell is composed of two sheets with marked one\nand two dimensional character respectively."
    },
    {
        "anchor": "Stochastic sampling of quadrature grids for the evaluation of\n  vibrational expectation values: The thermal lines method for the evaluation of vibrational expectation values\nof electronic observables [B. Monserrat, Phys. Rev. B 93, 014302 (2016)] was\nrecently proposed as a physically motivated approximation offering balance\nbetween the accuracy of direct Monte Carlo integration and the low\ncomputational cost of using local quadratic approximations. In this paper we\nreformulate thermal lines as a stochastic implementation of quadrature grid\nintegration, analyze the analytical form of its bias, and extend the method to\nmultiple point quadrature grids applicable to any factorizable harmonic or\nanharmonic nuclear wave function. The bias incurred by thermal lines is found\nto depend on the local form of the expectation value, and we demonstrate that\nthe use of finer quadrature grids along selected modes can eliminate this bias,\nwhile still offering a ~30% lower computational cost than direct Monte Carlo\nintegration in our tests.",
        "positive": "Influence of defects on ferroelectric and electrocaloric properties of\n  BaTiO$_3$: We report modifications of the ferroelectric and electrocaloric properties of\nBaTiO$_3$ by defects. For this purpose, we have combined \\textit{ab\ninitio}-based molecular dynamics simulations with a simple model for defects.\nWe find that different kinds of defects modify the ferroelectric transition\ntemperatures and polarization, reduce the thermal hysteresis of the transition\nand are no obstacle for a large caloric response. For a locally reduced\npolarization the ferroelectric transition temperature and the adiabatic\nresponse are slightly reduced. For polar defects an intriguing picture emerges.\nThe transition temperature is increased by polar defects and the temperature\nrange of the large caloric response is broadened. Even more remarkable, we find\nan inverse caloric effect in a broad temperature range."
    },
    {
        "anchor": "Phase-field modeling of crystal nucleation in undercooled liquids -- A\n  review: We review how phase-field models contributed to the understanding of various\naspects of crystal nucleation including homogeneous and heterogeneous\nprocesses, and their role in microstructure evolution. We recall results\nobtained both by the conventional phase-field approaches that rely on spatially\naveraged (coarse grained) order parameters in capturing freezing, and by the\nrecently developed phase-field crystal models that work on the molecular scale,\nwhile employing time averaged particle densities, and are regarded as simple\ndynamical density functional theories of classical particles. Besides simpler\ncases of homogeneous and heterogeneous nucleation, phenomena addressed by these\ntechniques include precursor assisted nucleation, nucleation in eutectic and\nphase separating systems, phase selection via competing nucleation processes,\ngrowth front nucleation (a process, in which grains of new orientations form at\nthe solidification front) yielding crystal sheaves and spherulites, and\ntransition between the growth controlled cellular and the nucleation dominated\nequiaxial solidification morphologies.",
        "positive": "Functional relations for the density functional exchange and correlation\n  functionals connecting functionals at three densities: It is shown that the DFT exchange and correlation functionals satisfy an\nexpression that couples exchange and correlation functionals and functional\nderivatives evaluated at three different densities and for two particle\nnumbers. This equation can be used as a stringent test to check the internal\nself-consistency of approximations to the exchange and correlation functionals."
    },
    {
        "anchor": "Why is EXAFS analysis for multicomponent metals so hard? Challenges and\n  opportunities for measuring ordering in complex concentrated alloys using\n  x-ray absorption spectroscopy: Short range order is a critical driver of properties (e.g. corrosion\nresistance and tensile strength) in multicomponent alloys such as complex\nconcentrated alloys (CCAs). Extended x-ray absorption fine structure (EXAFS) is\na powerful technique well suited for quantifying this short range order.Here,\nwe described in detail the characteristics of CCAs that make the already\nchallenging task of analyzing EXAFS data even more difficult. We then\nillustrate novel paths towards robust and scalable quantitative SRO analysis\nwhich will accelerate the scientific understanding and development of CCAs.",
        "positive": "Structural origin of plasticity in strained high-entropy alloy: High-entropy alloys (HEAs) are solid solutions of multiple elements with\nequal atomic ratios which present an innovative pathway for de novo alloy\nengineering. While there exist extensive studies to ascertain the important\nstructural aspects governing their mechanical behaviors, elucidating the\nunderlying deformation mechanisms still remains a challenge. Using atomistic\nsimulations, we probe the particle rearrangements in a yielding, model HEA\nsystem to understand the structural origin of its plasticity. We find the\nplastic deformation is initiated by irreversible topological fluctuations which\ntend to spatially localize in regions termed as soft spots which consist of\nparticles actively participating in slow vibrational motions, an observation\nstrikingly reminiscent of nonlinear glassy rheology. Due to the varying local\nelastic moduli resulting from the loss of compositional periodicity, these\nplastic responses exhibit significant spatial heterogeneity and are found to be\ninversely correlated with the distribution of local electronegativity. Further\nmechanical loading promotes the cooperativity among these local plastic events\nand triggers the formation of dislocation loops. As in strained crystalline\nsolids, different dislocation loops can further merge together and propagate as\nthe main carrier of large-scale plastic deformation. However, the energy\nbarriers located at the spatial regions with higher local electronegativity\nseverely hinders the motion of dislocations. By delineating the transient\nmechanical response in terms of atomic configuration, our computational\nfindings shed new light on understanding the nature of plasticity of\nsingle-phase HEA."
    },
    {
        "anchor": "Ab initio thermodynamics of hydrocarbons relevant to graphene growth at\n  solid and liquid Cu surfaces: Using ab initio thermodynamics, the stability of a wide range of hydrocarbon\nadsorbates under various chemical vapor deposition (CVD) conditions\n(temperature, methane and hydrogen pressures) used in experimental graphene\ngrowth protocols at solid and liquid Cu surfaces has been explored. At the\nemployed high growth temperatures around the melting point of Cu, we find that\ncommonly used thermodynamic models such as the harmonic oscillator model may no\nlonger be accurate. Instead, we account for the translational and rotational\nmobility of adsorbates using a recently developed hindered translator and\nrotator model or a two-dimensional ideal gas model. The thermodynamic\nconsiderations turn out to be crucial for explaining experimental results and\nallow us to improve and extend the findings of earlier theoretical studies\nregarding the role of hydrogen and hydrocarbon species in CVD. In particular,\nwe find that smaller hydrocarbons will completely dehydrogenate under most CVD\nconditions. For larger clusters our results show that metal-terminated and\nhydrogen-terminated edges have very similar stabilities. While both cluster\ntypes might thus form during the experiment, we show that the low binding\nstrength of clusters with hydrogen-terminated edges could result in instability\ntowards desorption.",
        "positive": "Quantitative analysis of valence photoemission spectra and quasiparticle\n  excitations at chromophore-semiconductor interfaces: Investigating quasiparticle excitations of molecules on surfaces through\nphotoemission spectroscopy forms a major part of nanotechnology research.\nResolving spectral features at these interfaces requires a comprehensive theory\nof electron removal and addition processes in molecules and solids which\ncaptures the complex interplay of image charges, thermal effects and\nconfigurational disorder. We here develop such a theory and calculate the\nquasiparticle energy-level alignment and the valence photoemission spectrum for\nthe prototype biomimetic solar cell interface between anatase TiO2 and the N3\nchromophore. By directly matching our calculated photoemission spectrum to\nexperimental data we clarify the atomistic origin of the chromophore peak at\nlow binding energy. This case study sets a new standard in the interpretation\nof photoemission spectroscopy at complex chromophore/semiconductor interfaces."
    },
    {
        "anchor": "Importance of the catalytic effect of the substrate in the functionality\n  of lubricant additives: the case of MoDTC: Molybdenum dithiocarbamates (MoDTCs) are lubricant additives very efficient\nin reducing the friction of steel and they are employed in a number of\nindustrial applications. The functionality of these additives is ruled by the\nchemical interactions occurring at the buried sliding interface, which are of\nkey importance for the improvement of the lubrication performance. Yet, these\ntribochemical processes are very difficult to monitor in real time. Ab initio\nmolecular dynamics simulations are the ideal tool to shed light into such a\ncomplicated reactivity. In this work we perform ab initio simulations, both in\nstatic and tribological conditions, to understand the effect of surface\noxidation on the tribochemical reactivity of MoDTC and we find that when the\nsurfaces are covered by oxygen, the first dissociative steps of the additives\nare significantly hindered. Our preliminary tribological tests on oxidized\nsteel discs support these results. Bare metallic surfaces are necessary for a\nstable adsorption of the additives, their quick decomposition, and the\nformation of a durable MoS$_2$ tribolayer. This work demonstrates the\nimportance of the catalytic role of the substrate and confirms the full\ncapability of the computational protocol in the pursuit of materials and\ncompounds more efficient in reducing friction.",
        "positive": "Statistical mechanics of kinks on a gliding screw dislocation: The ability of a body-centered cubic metal to deform plastically is limited\nby the thermally activated glide motion of screw dislocations, which are line\ndefects with a mobility exhibiting complex dependence on temperature, stress,\nand dislocation segment length. We derive an analytical expression for the\nvelocity of dislocation glide, based on a statistical mechanics argument, and\nidentify an apparent phase transition marked by a critical temperature above\nwhich the activation energy for glide effectively halves, changing from the\nformation energy of a double kink to that of a single kink. The analysis is in\nquantitative agreement with direct kinetic Monte Carlo simulations."
    },
    {
        "anchor": "Spin and orbital magnetic moments in perpendicularly magnetized\n  Ni$_{1-x}$Co$_{2+y}$O$_{4-z}$ epitaxial thin films: Effects of site-dependent\n  cation valence states: We carried out x-ray absorption spectroscopy (XAS) and x-ray magnetic\ncircular dichroism (XMCD) spectroscopy and investigated cation valence states\nand spin and orbital magnetic moments in the inverse-spinel ferrimagnet\nNi$_{1-x}$Co$_{2+y}$O$_{4-z}$ (NCO) epitaxial films with the perpendicular\nmagnetic anisotropy. We show that the oxygen pressure P$_{O2}$ during the film\ngrowth by pulsed laser deposition influences not only the cation stoichiometry\n(site-occupation) but also the cation valence state. Our XAS results show that\nthe Ni in the O$_{h}$-site is in the intermediate valence state between +2 and\n+3, Ni$^{(2+\\delta)+}$ (0<$\\delta$<1), whose nominal valence state (the\n$\\delta$ value) varies depending on P$_{O2}$. On the other hand, the Co in the\noctahedral (O$_{h}$) and tetrahedral (T$_{d}$) sites respectively have the\nvalence state close to +3 and +2. We also find that the XMCD signals originate\nmainly from the T$_{d}$-site Co$^{2+}$ (Co$_{Td}$) and O$_{h}$-site\nNi$^{(2+\\delta)+}$ (Ni$_{Oh}$), indicating that these cation valence states are\nthe key in determining the magnetic and transport properties of NCO films.\nInterestingly, the valence state of Ni$^{(2+\\delta)+}$ that gives rise to the\nXMCD signal remains unchanged independent of P$_{O2}$. The electronic structure\nof Ni$^{(2+\\delta)+}$ that is responsible for the magnetic moment and\nelectrical conduction differs from those of Ni$^{2+}$ and Ni$^{3+}$. In\naddition, the orbital magnetic moment originating from Co$_{Td}$ is as large as\n0.14 $\\mu_{B}/Co_{Td}$ and parallel to the magnetization while the Ni$_{Oh}$\norbital moment is as small as 0.07 $\\mu_{B}/Ni_{Oh}$ and is rather isotropic.\nThe Co$_{Td}$ therefore plays the key role in the perpendicular magnetic\nanisotropy of the films. Our results demonstrate the significance of the\nsite-dependent cations valence states for the magnetic and transport properties\nof NCO films.",
        "positive": "A First-Principles Study of Zinc Oxide Honeycomb Structures: We present a first-principles study of the atomic, electronic, and magnetic\nproperties of two-dimensional (2D), single and bilayer ZnO in honeycomb\nstructure and its armchair and zigzag nanoribbons. In order to reveal the\ndimensionality effects, our study includes also bulk ZnO in wurtzite,\nzincblende, and hexagonal structures. The stability of 2D ZnO, its nanoribbons\nand flakes are analyzed by phonon frequency, as well as by finite temperature\nab initio molecular-dynamics calculations. 2D ZnO in honeycomb structure and\nits armchair nanoribbons are nonmagnetic semiconductors but acquire net\nmagnetic moment upon the creation of zinc-vacancy defect. Zigzag ZnO\nnanoribbons are ferromagnetic metals with spins localized at the oxygen atoms\nat the edges and have high spin polarization at the Fermi level. However, they\nchange to nonmagnetic metal upon termination of their edges with hydrogen\natoms. From the phonon calculations, the fourth acoustical mode specified as\ntwisting mode is also revealed for armchair nanoribbon. Under tensile stress\nthe nanoribbons are deformed elastically maintaining honeycomblike structure\nbut yield at high strains. Beyond yielding point honeycomblike structure\nundergo a structural change and deform plastically by forming large polygons.\nThe variation in the electronic and magnetic properties of these nanoribbons\nhave been examined under strain. It appears that plastically deformed\nnanoribbons may offer a new class of materials with diverse properties."
    },
    {
        "anchor": "Energy conversion processes with perovskite-type materials: Mixed oxides derived from the perovskite structure by combination of A- and\nB-site elements and by partial substitution of oxygen provide an immense\nplayground of physico-chemical properties. Here, we account for own research\nconducted at the Paul Scherrer Institute on perovskite-type oxides and\noxynitrides used in electrochemical, photo(electro)chemical and catalytic\nprocesses aiming at facing energy relevant issues.",
        "positive": "Low activation, refractory, high entropy alloys for nuclear applications: Two new, low activation high entropy alloys (HEAs) TiVZrTa and TiVCrTa are\nstudied for use as in-core, structural nuclear materials for in-core nuclear\napplications. Low-activation is a desirable property for nuclear reactors, in\nan attempt to reduce the amount of high level radioactive waste upon\ndecommissioning, and for consideration in fusion applications.The alloy TiVNbTa\nis used as a starting composition to develop two new HEAs; TiVZrTa and TiVCrTa.\nThe new alloys exhibit comparable indentation hardness and modulus, to the\nTiVNbTa alloy in the as-cast state. After heavy ion implantation the new alloys\nshow an increased irradiation resistance."
    },
    {
        "anchor": "Terahertz-driven magnetism dynamics in the orthoferrite DyFeO3: Terahertz driven magnetization dynamics are explored in the orthoferrite\nDyFeO3. A high-field, single cycle THz pulse is used to excite magnon modes in\nthe crystal together with other resonances. Both quasi-ferromagnetic and\nquasi-antiferromagnetic magnon modes are excited and appear in time-resolved\nmeasurements of the Faraday rotation. Other modes are also observed in the\nmeasurements of the time-resolved linear birefringence. Analysis of the\nexcitation process reveals that despite larger than expected electro-optical\nsusceptibility it is mainly the THz magnetic field that couples to the\nquasi-ferromagnetic and quasi-antiferromagnetic magnon branches.",
        "positive": "Dielectric Properties of Noncrystalline HfSiON: The dielectric properties of noncrystalline hafnium silicon oxynitride\n(HfSiON) films with a variety of atomic compositions were investigated. The\nfilms were deposited by reactive sputtering of Hf and Si in an O, N, and Ar\nmixture ambient. The bonding states, band-gap energies, atomic compositions,\nand crystallinities were confirmed by X-ray photoelectron spectroscopy (XPS),\nreflection electron energy loss spectroscopy (REELS), Rutherford backscattering\nspectrometry (RBS), and X-ray diffractometry (XRD), respectively. The optical\n(high-frequency) dielectric constants were optically determined by the square\nof the reflective indexes measured by ellipsometry. The static dielectric\nconstants were electrically estimated by the capacitance of Au/HfSiON/Si(100)\nstructures. It was observed that low N incorporation in the films led to the\nformation of only Si-N bonds without Hf-N bonds. An abrupt decrease in band-gap\nenergies was observed at atomic compositions corresponding to the boundary\nwhere Hf-N bonds start to form. By combining the data for the atomic\nconcentrations and bonding states, we found that HfSiON can be regarded as a\npseudo-quaternary alloy consisting of four insulating components: SiO$_2$,\nHfO$_2$, Si$_3$N$_4$, and Hf$_3$N$_4$. The optical and static dielectric\nconstants for the films showed a nonlinear dependence on the N concentration,\nwhose behavior can be understood in terms of abrupt Hf-N bond formation."
    },
    {
        "anchor": "Detection of boson peak and fractal dynamics of disordered system using\n  terahertz spectroscopy: Disordered systems exhibit universal excitation, referred to as the boson\npeak, in the terahertz region. Meanwhile, the so-called fracton is expected to\nappear in the nanoscale region owing to the self-similar structure of monomers\nin polymeric glasses. We demonstrate that such excitations can be detected\nusing terahertz spectroscopy. For the interaction between terahertz light and\nthe vibrational density of states of the fractal structure, we formulate an\ninfrared light-vibration coupling coefficient for the fracton region.\nAccordingly, we show that information concerning fractal and fracton dimensions\nappears in the exponent of the absorption coefficient. Finally, using terahertz\ntime-domain spectroscopy and low-frequency Raman scattering, we experimentally\nobserve these universal excitations in a protein lysozyme system that has an\nintrinsically disordered and self-similar nature in a single supramolecule.\nThese findings are applicable to disordered and polymeric glasses in general\nand will be key to understanding universal dynamics of disordered systems by\nterahertz light.",
        "positive": "Splitting of a nondegenerate phonon mode in PrFe3(BO3)4: 4f\n  crystal-field level between TO and LO phonon frequencies: A new effect originating from the crystal-field-excitation - phonon coupling\nwas observed (in the far infrared spectra of a multiferroic PrFe3(BO3)4). The\nreststrahlen band corresponding to the A2 symmetry nondegenerate phonon mode\nnear 50 cm-1 (1.5 THz) splits into two bands at about 100 K, well above TN = 32\nK. These bands shift and narrow progressively with further lowering the\ntemperature, demonstrating pronounced peculiarities at TN. The observed effects\nwere explained by an interaction of the A2 phonon mode with the 4f\ncrystal-field electronic excitation of Pr3+ whose frequency falls into the TO -\nLO frequency region of the phonon mode. Inversion of the TO and LO frequencies\nfor the electronic excitation and a formation of coupled electron-phonon modes\nare discussed. Fitting of the TO frequency vs temperature experimental plots by\ntheoretical curves revealed the value 14.6 cm-1 for the electron-phonon\ncoupling constant."
    },
    {
        "anchor": "Comparison of jump frequencies of 111In/Cd tracer atoms in Sn3R and In3R\n  phases having the L12 structure (R = rare-earth): Measurements were made of jump frequencies of 111In/Cd tracer atoms on the\nSn-sublattice in rare-earth tri-stannides having the L12 crystal structure via\nperturbed angular correlation spectroscopy (PAC). Phases studied were Sn3R (R=\nLa, Ce, Pr, Nd, Sm and Gd). Earlier measurements on isostructural rare-earth\ntri-indides showed that the dominant diffusion mechanism changed along that\nseries. The dominant mechanism was determined by comparing jump frequencies\nmeasured at opposing phase boundary compositions (that is, more In-rich and\nmore In-poor). Jump frequencies were observed to be greater at the In-rich\nboundary composition in light lanthanide indides and greater at the In-poor\nboundary composition in heavy-lanthanide indides. These observations were\nattributed to predominance of diffusion via rare-earth vacancies in the former\ncase and indium vacancies in the latter. Contrary to results for the indides,\njump frequencies found in the present work are greater for the Sn-poor boundary\ncompositions of the stannides, signaling that diffusive jumps are controlled by\nSn-vacancies. Possible origins of these differences in diffusion mechanisms are\ndiscussed.",
        "positive": "Model Hamiltonian for Topological Insulators: In this paper we give the full microscopic derivation of the model\nHamiltonian for the three dimensional topological insulators in the $Bi_2Se_3$\nfamily of materials ($Bi_2Se_3$, $Bi_2Te_3$ and $Sb_2Te_3$). We first give a\nphysical picture to understand the electronic structure by analyzing atomic\norbitals and applying symmetry principles. Subsequently, we give the full\nmicroscopic derivation of the model Hamiltonian introduced by Zhang {\\it et al}\n[\\onlinecite{zhang2009}] based both on symmetry principles and the ${\\bf\nk}\\cdot{\\bf p}$ perturbation theory. Two different types of $k^3$ terms, which\nbreak the in-plane full rotation symmetry down to three fold rotation symmetry,\nare taken into account. Effective Hamiltonian is derived for the topological\nsurface states. Both the bulk and the surface models are investigated in the\npresence of an external magnetic field, and the associated Landau level\nstructure is presented. For more quantitative fitting to the first principle\ncalculations, we also present a new model Hamiltonian including eight energy\nbands."
    },
    {
        "anchor": "F and Vk centres in LaF3, CeF3 crystals: Optical absorption properties of additively colored in calcium vapor and\nX-irradiated crystals with tysonite structure, LaF3 and CeF3, were studied in\n1.5-5.5 eV energy range. Photobleaching with 1.9 eV light and dichroism of the\nabsorption bands were investigated.The absorption band at 3.75 eV with half\nwidth of 1.1 eV is observed in X-irradiated LaF3, similar to the\nVk-centre-bands observed in other fluorides. No such band is observed in\nX-irradiated CeF3.\n  In additively colored CeF3 absorption bands at 1.7 eV, 2.15 eV are observed.\nThese bands can be attributed to F centres. Additive coloration upon heating in\ncalcium vapor did not produce any new absorption band in LaF3 crystals while\nformation of metallic inclusions, most likely La precipitates were observed.\nFor X-irradiated LaF3 and CeF3, at temperature below 110K the photo-bleachable,\ndichroic bands are observed: near 2 eV -band perpendicular to c-axis, 2.6-2.7\neV -band along c-axis. F centres occupying the vacancies of fluoride F(1)\nlayers in X-irradiated crystals and F-centres occupying all fluoride vacancies\nin additively colored crystals are proposed to be observed",
        "positive": "Design and Application of Variable Temperature Environmental Capsule for\n  Scanning Electron Microscopy in Gases and Liquids at Ambient Conditions: Scanning electron microscopy (SEM) of nanoscale objects in their native\nconditions and at different temperatures are of critical importance in\nrevealing details of their interactions with ambient environments. Currently\navailable environmental capsules are equipped with thin electron transparent\nmembranes and allow imaging the samples at atmospheric pressure. However these\ncapsules do not provide the temperature control over the sample. Here we\ndeveloped and tested a thermoelectric cooling / heating setup for available\nenvironmental capsules to allow ambient pressure in situ SEM studies over the\n-15 {\\deg}C to 100 {\\deg}C temperature range in gaseous, liquid, and frozen\nenvironments. The design of the setup also allows correlation of the SEM with\noptical microscopy and spectroscopy. As a demonstration of the possibilities of\nthe developed approach, we performed real-time in situ microscopy studies of\nwater condensation on a surface of wing scales of Morpho sulkowskyi butterfly.\nWe have found that the initial water nucleation takes place on the top of the\nscale ridges. These results confirmed earlier discovery of a polarity gradient\nof the ridges of Morpho butterflies. Our developed thermoelectric cooling /\nheating setup for available SEM environmental capsules promises to impact\ndiverse needs for in-situ nano-characterization including materials science and\ncatalysis, micro-instrumentation and device reliability, chemistry and biology."
    },
    {
        "anchor": "Magnetoelectric coupling in a ferroelectric/ferromagnetic chain revealed\n  by ferromagnetic resonance: Understanding the multiferroic coupling is one of the key issues in the feld\nof multiferroics. As shown here theoretically, the ferromagnetic resonance\n(FMR) renders possible an access to the magnetoelectric coupling coefficient in\ncomposite multiferroics. This we evidence by a detailed analysis and numerical\ncalculations of FMR in an unstrained chain of BaTiO3 in the tetragonal phase in\ncontact with Fe, including the effect of depolarizing field. The spectra of the\nabsorbed power in FMR are found to be sensitive to the orientation of the\ninterface electric polarization and to an applied static electric field. Here\nwe propose a method for measuring the magnetoelectric coupling coefficient by\nmeans of FMR.",
        "positive": "Band dispersion and electronic lifetimes in crystalline organic\n  semiconductors: The consequences of several microscopic interactions on the photoemission\nspectra of crystalline organic semiconductors (OSC) are studied theoretically.\nIt is argued that their relative roles can be disentangled by analyzing both\ntheir temperature and their momentum/energy dependence. Our analysis shows that\nthe polaronic thermal band narrowing, that is the foundation of most theories\nof electrical transport in OSC, is inconsistent in the range of microscopic\nparameters appropriate for these materials. An alternative scenario is proposed\nto explain the experimental trends."
    },
    {
        "anchor": "Investigating the magnetic ground state of the skyrmion host material\n  Cu$_{2}$OSeO$_{3}$ using long-wavelength neutron diffraction: We present long-wavelength neutron diffraction data measured on both single\ncrystal and polycrystalline samples of the skyrmion host material\nCu$_{2}$OSeO$_{3}$. We observe magnetic satellites around the $(0\\bar{1}1)$\ndiffraction peak not accessible to other techniques, and distinguish helical\nfrom conical spin textures in reciprocal space. We confirm successive\ntransitions from helical to conical to field polarised ordered spin textures as\nthe external magnetic field is increased. The formation of a skyrmion lattice\nwith propagation vectors perpendicular to the field direction is observed in a\nregion of the field-temperature phase diagram that is consistent with previous\nreports. Our measurements show that not only the field-polarised phase but also\nthe helical ground state are made up of ferrimagnetic clusters instead of\nindividual spins. These clusters are distorted Cu tetrahedra, where the spin on\none Cu ion is anti-aligned with the spin on the three other Cu ions.",
        "positive": "Non-parametric Local Pseudopotentials with Machine Learning: a Tin\n  Pseudopotential Built Using Gaussian Process Regression: We present novel non-parametric representation math for local\npseudopotentials (PP) based on Gaussian Process Regression (GPR). Local\npseudopotentials are needed for materials simulations using Orbital-Free\nDensity Functional Theory (OF-DFT) to reduce computational cost and to allow\nkinetic energy functional (KEF) application only to the valence density.\nMoreover, local PPs are important for the development of accurate KEFs for\nOF-DFT as they are only available for a limited number of elements. We optimize\nlocal PPs of tin (Sn) using GP regression to reproduce the experimental lattice\nconstants of {\\alpha}- and \\b{eta}-Sn, the energy difference between these two\nphases as well as their electronic structure and charge density distributions,\nwhich are obtained with Kohn-Sham Density Functional Theory employing\nsemi-local PPs. The use of a non-parametric GPR-based PP representation avoids\ndifficulties associated with the use of parametrized functions and has the\npotential to construct an optimal local PP independent of prior assumptions.\nThe GPR-based Sn local PP results in well-reproduced bulk properties of\n{\\alpha}- and \\b{eta}-tin, and electronic valence densities similar to those\nobtained with semi-local PP."
    },
    {
        "anchor": "Antisite disorder and phase segregation in Mn$_{2}$NiSn: A systematic study of crystal structure, local structure, magnetic and\ntransport properties in quenched and temper annealed Ni$_{2-x}$Mn$_{1+x}$Sn\nalloys indicate the formation of Mn$_3$Sn type structural defects caused by an\nantisite disorder between Mn and Sn occupying the Y and Z sublattices of\nX$_2$YZ Heusler structure. The antisite disorder is caused by the substitution\nof Ni by Mn at the X sites. On temper annealing, these defects segregate and\nphase separate into $L2_1$ Heusler and $D0_{19}$ Mn$_3$Sn type phases.",
        "positive": "Thin films with precisely engineered nanostructures: Synthesis of rationally designed nanostructured materials with optimized\nmechanical properties, e.g., high strength with considerable ductility,\nrequires rigorous control of diverse microstructural parameters including the\nmean size, size dispersion and spatial distribution of grains. However,\ncurrently available synthesis techniques can seldom satisfy these requirements.\nHere, we report a new methodology to synthesize thin films with unprecedented\nmicrostructural control via systematic, in-situ seeding of nanocrystals into\namorphous precursor films. When the amorphous films are subsequently\ncrystallized by thermal annealing, the nanocrystals serve as preferential grain\nnucleation sites and control their microstructure. We demonstrate the\ncapability of this approach by precisely tailoring the size, geometry and\nspatial distribution of nanostructured grains in structural (TiAl) as well as\nfunctional (TiNi) thin films. The approach, which is applicable to a broad\nclass of metallic alloys and ceramics, enables explicit microstructural control\nof thin film materials for a wide spectrum of applications."
    },
    {
        "anchor": "Electrical conductivity of vanadium dioxide switching channel: The electrical conductivity of the switching channel of vanadium dioxide\nthin-film sandwich structures is studied over a wide temperature range (15-300\nK). It is shown that the electrical resistance of the channel varies with\ntemperature as R~exp(aT-b/T) in the high-temperature region (above 70 K). The\nexperimental results are discussed from the viewpoint of the small polaron\nhopping conduction theory which takes into account the influence of thermal\nlattice vibrations onto the resonance integral.",
        "positive": "Room-temperature ferromagnetism in dielectric GaN(Gd): We present an explanation of recently observed giant magnetic moment and\nroom-temperature ferromagnetism in the dielectric GaN doped with Gd. Our\napproach uses the polarization mechanism of exchange interaction, which occurs\nif the d-level of Gd appears in the bandgap close to the valence band edge.\nCalculated ferromagnetic critical temperature and the value of the magnetic\nmoment well correspond to experimental findings."
    },
    {
        "anchor": "Complex magnetic phases enriched by charge density waves in topological\n  semimetals GdSb_xTe_{2-x-\u03b4}: The interplay of crystal symmetry, magnetism, band topology and electronic\ncorrelation can be the origin of quantum phase transitions in condensed matter.\nParticularly, square-lattice materials have been serving as a versatile\nplatform to study the rich phenomena resulting from that interplay. In this\nwork, we report a detailed magnetic study on the square-lattice based magnetic\ntopological semimetals GdSb_{x}Te_{2-x-{\\delta}}. We report the H-T magnetic\nphase diagrams along three crystallographic orientations and show that, for\nthose materials where a charge density wave distortion is known to exist, many\ndifferent magnetic phases are identified. In addition, the data provides a clue\nto the existence of an antiferromagnetic skyrmion phase, which has been\ntheoretically predicted but not experimentally confirmed in a bulk material\nyet.",
        "positive": "A polarization-induced 2D hole gas in undoped gallium nitride quantum\n  wells: The long-missing polarization-induced two-dimensional hole gas is finally\nobserved in undoped gallium nitride quantum wells. Experimental results provide\nunambiguous proof that a 2D hole gas in GaN grown on AlN does not need acceptor\ndoping, and can be formed entirely by the difference in the internal\npolarization fields across the semiconductor heterojunction. The measured 2D\nhole gas densities, about $4 \\times 10^{13}$ cm$^{-2}$, are among the highest\namong all known semiconductors and remain unchanged down to cryogenic\ntemperatures. Some of the lowest sheet resistances of all wide-bandgap\nsemiconductors are seen. The observed results provide a new probe for studying\nthe valence band structure and transport properties of wide-bandgap nitride\ninterfaces, and simultaneously enable the missing component for gallium\nnitride-based p-channel transistors for energy-efficient electronics."
    },
    {
        "anchor": "Machine learning with systematic density-functional theory calculations:\n  Application to melting temperatures of single and binary component solids: A combination of systematic density functional theory (DFT) calculations and\nmachine learning techniques has a wide range of potential applications. This\nstudy presents an application of the combination of systematic DFT calculations\nand regression techniques to the prediction of the melting temperature for\nsingle and binary compounds. Here we adopt the ordinary least-squares\nregression (OLSR), partial least-squares regression (PLSR), support vector\nregression (SVR) and Gaussian process regression (GPR). Among the four kinds of\nregression techniques, the SVR provides the best prediction. In addition, the\ninclusion of physical properties computed by the DFT calculation to a set of\npredictor variables makes the prediction better. Finally, a simulation to find\nthe highest melting temperature toward the efficient materials design using\nkriging is demonstrated. The kriging design finds the compound with the highest\nmelting temperature much faster than random designs. This result may stimulate\nthe application of kriging to efficient materials design for a broad range of\napplications.",
        "positive": "Magnetic glass in Shape Memory Alloy : Ni45Co5Mn38Sn12: The first order martensitic transition in the ferromagnetic shape memory\nalloy Ni45Co5Mn38Sn12 is also a magnetic transition and has a large field\ninduced effect. While cooling in the presence of field this first order\nmagnetic martensite transition is kinetically arrested. Depending on the\ncooling field, a fraction of the arrested ferromagnetic austenite phase\npersists down to the lowest temperature as a magnetic glassy state, similar to\nthe one observed in various intermetallic alloys and in half doped manganites.\nA detailed investigation of this first order ferromagnetic austenite (FM-A) to\nlow magnetization martensite (LM-M) state transition as a function of\ntemperature and field has been carried out by magnetization measurements.\nExtensive cooling and heating in unequal field (CHUF) measurements and a novel\nfield cooled protocol for isothermal MH measurements (FC-MH) are utilized to\ninvestigate the glass like arrested states and show a reverse martensite\ntransition. Finally, we determine a field -temperature (HT) phase diagram of\nNi45Co5Mn38Sn12 from various magnetization measurements which brings out the\nregions where thermodynamic and metastable states co-exist in the HT space\nclearly depicting this system as a 'Magnetic Glass'."
    },
    {
        "anchor": "Current-induced switching of thin film $\u03b1$-Fe$_2$O$_3$ devices\n  imaged using a scanning single-spin microscope: Electrical switching of N\\'eel order in an antiferromagnetic insulator is\ndesirable as a basis for memory applications. Unlike electrically-driven\nswitching of ferromagnetic order via spin-orbit torques, electrical switching\nof antiferromagnetic order remains poorly understood. Here we investigate the\nlow-field magnetic properties of 30 nm thick, c-axis oriented\n$\\alpha$-Fe$_2$O$_3$ Hall devices using a diamond nitrogen-vacancy (NV) center\nscanning microscope. Using the canted moment of $\\alpha$-Fe$_2$O$_3$ as a\nmagnetic handle on its N\\'eel vector, we apply a saturating in-plane magnetic\nfield to create a known initial state before letting the state relax in low\nfield for magnetic imaging. We repeat this procedure for different in-plane\norientations of the initialization field. We find that the magnetic field\nimages are characterized by stronger magnetic textures for fields along\n$[\\bar{1}\\bar{1}20]$ and $[11\\bar{2}0]$, suggesting that despite the expected\n3-fold magneto-crystalline anisotropy, our $\\alpha$-Fe$_2$O$_3$ thin films have\nan overall in-plane uniaxial anisotropy. We also study current-induced\nswitching of the magnetic order in $\\alpha$-Fe$_2$O$_3$. We find that the\nfraction of the device that switches depends on the current pulse duration,\namplitude and direction relative to the initialization field. Specifically, we\nfind that switching is most efficient when current is applied along the\ndirection of the initialization field.",
        "positive": "High Thermal Conductivity in Wafer Scale Cubic Silicon Carbide Crystals: High thermal conductivity electronic materials are critical components for\nhigh-performance electronic and photonic devices as either active functional\nmaterials or thermal management materials. We report an isotropic high thermal\nconductivity over 500 W m-1K-1 at room temperature in high-quality wafer-scale\ncubic silicon carbide (3C-SiC) crystals, which is the second highest among\nlarge crystals (only surpassed by diamond). Furthermore, the corresponding\n3C-SiC thin films are found to have record-high in-plane and cross-plane\nthermal conductivity, even higher than diamond thin films with equivalent\nthicknesses. Our results resolve a long-lasting puzzle that the literature\nvalues of thermal conductivity for 3C-SiC are perplexingly lower than the\nstructurally more complex 6H-SiC. Further analysis reveals that the observed\nhigh thermal conductivity in this work arises from the high purity and high\ncrystal quality of 3C-SiC crystals which excludes the exceptionally strong\ndefect-phonon scatterings in 3C-SiC. Moreover, by integrating 3C-SiC with other\nsemiconductors by epitaxial growth, we show that the measured 3C-SiC-Si TBC is\namong the highest for semiconductor interfaces. These findings not only provide\ninsights for fundamental phonon transport mechanisms, also suggest that 3C-SiC\nmay constitute an excellent wide-bandgap semiconductor for applications of\npower electronics as either active components or substrates."
    },
    {
        "anchor": "Aging of a nanostructured Zn50Se50 alloy produced by mechanical alloying: The aging of a nanocrystalline equiatomic ZnSe alloy produced by mechanical\nalloying was investigated using X-ray diffraction (XRD) and differential\nscanning calorimetry (DSC) techniques. The measured XRD patterns showed that Se\natoms located at interfacial component migrated with aging giving raise to a\ncrystalline selenium (c-Se) phase. DSC spectra of heat-treated samples at\ntemperatures above 221oC followed by quenching showed that the c-Se particles\nchanged to the amorphous state. It was also observed that the as-milled and\naged samples are highly hydrophilic. The lattice parameters and the average\ncrystallite sizes were calculated as a function of time of aging and\ntemperature of heat treatment.",
        "positive": "Layer-by-layer resistive switching: multi-state functionality due to\n  electric-field-induced healing of \"dead\" layers: Materials exhibiting reversible resistive switching in electrical fields are\nhighly demanded for functional elements in oxide electronics. In particular,\nmultilevel switching effects allow for advanced applications like neuromorphic\ncircuits. Here we report on a structurally driven switching mechanism involving\nthe so-called `dead layers' of perovskite manganite surfaces. Forming a tunnel\nbarrier whose thickness can be changed in monolayer steps by electrical fields,\nthe switching effect exhibits well-defined and robust resistive states."
    },
    {
        "anchor": "Cooling Dynamics of a Gold Nanoparticle in a Host Medium Under Ultrafast\n  Laser Pulse Excitation: A Ballistic-Diffusive Approach: We present a numerical model allowing to determine the electron and lattice\ntemperature dynamics in a gold nanoparticle under subpicosecond pulsed\nexcitation, as well as that of the surrounding medium. For this, we have used\nthe electron-phonon coupling equation in the particle with a source term linked\nwith the laser pulse, and the ballistic-diffusive equations for heat conduction\nin the host medium. Our results show that the heat transfer rate from the\nparticle to the matrix is significantly smaller than the prediction of\nFourier's law. Consequently, the particle temperature rise is much larger and\nits cooling dynamics is much slower than that obtained using Fourier's law,\nwhich is attributed to the nonlocal and nonequilibrium heat conduction in the\nvicinity of the nanoparticle. These results are expected to be of great\nimportance for interpreting pump-probe experiments performed on single\nnanoparticles or nanocomposite media.",
        "positive": "Crystal Toolkit: A Web App Framework to Improve Usability and\n  Accessibility of Materials Science Research Algorithms: Crystal Toolkit is an open source tool for viewing, analyzing and\ntransforming crystal structures, molecules and other common forms of materials\nscience data in an interactive way. It is intended to help beginners rapidly\ndevelop web-based apps to explore their own data or to help developers make\ntheir research algorithms accessible to a broader audience of scientists who\nmight not have any training in computer programming and who would benefit from\ngraphical interfaces. Crystal Toolkit comes with a library of ready-made\ncomponents that can be assembled to make complex web apps: simulation of powder\nand single crystalline diffraction patterns, convex hull phase diagrams,\nPourbaix diagrams, electronic band structures, analysis of local chemical\nenvironments and symmetry, and more. Crystal Toolkit is now powering the\nMaterials Project website frontend, providing user-friendly access to its\ndatabase of computed materials properties. In the future, it is hoped that new\nvisualizations might be prototyped using Crystal Toolkit to help explore new\nforms of data being generated by the materials science community, and that this\nin turn can help new materials scientists develop intuition for how their data\nbehaves and the insights that might be found within. Crystal Toolkit will\nremain a work-in-progress and is open to contributions from the community."
    },
    {
        "anchor": "Ultrafast Temperature Profile Calculation in Ic Chips: One of the crucial steps in the design of an integrated circuit is the\nminimization of heating and temperature non-uniformity. Current temperature\ncalculation methods, such as finite element analysis and resistor networks have\nconsiderable computation times, making them incompatible for use in routing and\nplacement optimization algorithms. In an effort to reduce the computation time,\nwe have developed a new method, deemed power blurring, for calculating\ntemperature distributions using a matrix convolution technique in analogy with\nimage blurring. For steady state analysis, power blurring was able to predict\nhot spot temperatures within 1 degree C with computation times 3 orders of\nmagnitude faster than FEA. For transient analysis the computation times where\nenhanced by a factor of 1000 for a single pulse and around 100 for multiple\nfrequency application, while predicting hot spot temperature within about 1\ndegree C. The main strength of the power blurring technique is that it exploits\nthe dominant heat spreading in the silicon substrate and it uses superposition\nprinciple. With one or two finite element simulations, the temperature point\nspread function for a sophisticated package can be calculated. Additional\nsimulations could be used to improve the accuracy of the point spread function\nin different locations on the chip. In this calculation, we considered the\ndominant heat transfer path through the back of the IC chip and the heat sink.\nHeat transfer from the top of the chip through metallization layers and the\nboard is usually a small fraction of the total heat dissipation and it is\nneglected in this analysis.",
        "positive": "Towards pump-probe experiments of defect dynamics with short ion beam\n  pulses: A novel, induction type linear accelerator, the Neutralized Drift Compression\neXperiment (NDCX-II), is currently being commissioned at Berkeley Lab. This\naccelerator is designed to deliver intense (up to 3x1011 ions/pulse), 0.6 to\n~600 ns duration pulses of 0.13 to 1.2 MeV lithium ions at a rate of about 2\npulses per minute onto 1 to 10 mm scale target areas. When focused to\nmm-diameter spots, the beam is predicted to volumetrically heat micrometer\nthick foils to temperatures of ~30,000 K. At lower beam power densities, the\nshort excitation pulse with tunable intensity and time profile enables\npump-probe type studies of defect dynamics in a broad range of materials. We\nbriefly describe the accelerator concept and design, present results from beam\npulse shaping experiments and discuss examples of pump-probe type studies of\ndefect dynamics following irradiation of materials with intense, short ion beam\npulses from NDCX-II."
    },
    {
        "anchor": "Information Processing with Pure Spin Currents in Silicon: Spin\n  Injection, Extraction, Manipulation and Detection: We demonstrate that information can be transmitted and processed with pure\nspin currents in silicon. Fe/Al2O3 tunnel barrier contacts are used to produce\nsignificant electron spin polarization in the silicon, generating a spin\ncurrent which flows outside of the charge current path. The spin orientation of\nthis pure spin current is controlled in one of three ways: (a) by switching the\nmagnetization of the Fe contact, (b) by changing the polarity of the bias on\nthe Fe/Al2O3 (injector) contact, which enables the generation of either\nmajority or minority spin populations in the Si, providing a way to\nelectrically manipulate the injected spin orientation without changing the\nmagnetization of the contact itself, and (c) by inducing spin precession\nthrough application of a small perpendicular magnetic field. Spin polarization\nby electrical extraction is as effective as that achieved by the more common\nelectrical spin injection. The output characteristics of a planar silicon three\nterminal device are very similar to those of non-volatile giant\nmagnetoresistance metal spin-valve structures",
        "positive": "Electrochemical Properties and Crystal Structure of Li+ / H+\n  Cation-exchanged LiNiO2: LiNiO2 has high energy density but easily reacts with moisture in the\natmosphere and deteriorates. We performed qualitative and quantitative\nevaluations of the degraded phase of LiNiO2 and the influence of the structural\nchange on the electrochemical properties of the phase. Li1-xHxNiO2 phase with\ncation exchange between Li+ and H+ was confirmed by thermogravimetric analysis\nand Karl Fischer titration measurement. As the H concentration in LiNiO2\nincreased, the rate capability deteriorated, especially in the low-temperature\nrange and under low state of charge. Experimental and density functional theory\n(DFT) calculation results suggested that this outcome was due to increased\nactivation energy of Li+ diffusion owing to cation exchange. Rietveld analysis\nof X-ray diffraction and DFT calculation confirmed that the c lattice parameter\nand Li-O layer reduced because of the Li+/H+ cation exchange. These results\nindicate that LiNiO2 modified in the atmosphere has a narrowed Li-O layer,\nwhich is the Li diffusion path, and the rate characteristics are degraded."
    },
    {
        "anchor": "Comprehensive ab initio study of effects of alloying elements on\n  generalized stacking fault energies of Ni and Ni$_3$Al: Excellent high-temperature mechanical properties of Ni-based single crystal\nsuperalloys (NSCSs) are attributed to the yield strength anomaly of Ni$_{3}$Al\nthat is intimately related to generalized stacking fault energies (GSFEs).\nTherefore, clarifying the effects of alloying elements on the GSFEs is of great\nsignificance for alloys design. Here, by means of ab initio density functional\ntheory calculations, we systematically calculated the GSFEs of different slip\nsystems of Ni and Ni$_{3}$Al without and with alloying elements using the alias\nshear method. We obtained that for Ni, except for magnetic elements Mn, Fe, and\nCo, most of alloying elements decrease the unstable stacking fault energy\n($\\gamma_{usf}$) of the $[01\\bar{1}](111)$ and $[11\\bar{2}](111)$ slip systems\nand also decrease the stable stacking fault energy ($\\gamma_{sf}$) of the\n$[11\\bar{2}](111)$ slip system. For Ni$_{3}$Al, most of alloying elements in\ngroups IIIB-VIIB show a strong Al site preference. Except for Mn and Fe, the\nelements in groups VB-VIIB and the first column of group VIII increase the\nvalues of $\\gamma_{usf}$ of different slip systems of Ni$_{3}$Al. On the other\nhand, the elements in groups IIIB-VIIB also increase the value of\n$\\gamma_{sf}$. We found that Re is an excellent strengthening alloying element\nthat significantly increases the slip barrier of the tailing slip process for\nNi, and also enhances the slip barrier of the leading slip process of three\nslip systems for Ni$_{3}$Al. W and Mo exhibit similar effects as Re. We\npredicted that Os, Ru, and Ir are good strengthening alloying elements as well,\nsince they show the strengthening effects on both the leading and tailing slip\nprocess for Ni and Ni$_{3}$Al.",
        "positive": "Growth at high substrate coverage can decrease the grain boundary\n  roughness of 2D materials: Grain boundary roughness can affect electronic and mechanical properties of\ntwo-dimensional materials. This roughness depends crucially on the growth\nprocess by which the two-dimensional material is formed. To investigate the key\nmechanisms that govern the roughness, we have performed kinetic Monte Carlo\nsimulations of a simple model that includes particle attachment, detachment,\nand diffusion. We have studied the closure of the gap between two flakes during\ngrowth, and the subsequent formation of the grain boundary (GB) for a broad\nrange of model parameters. The well known near-equilibrium (attachment-limited)\nand unstable (diffusion-limited) growth regimes are identified, but we also\nobserve a third regime when the precursor flux is sufficiently high to fully\ncover the gap between the edges. This high coverage regime forms GBs with\nspatially uncorrelated roughness, which quickly relax to smoother\nconfigurations. Extrapolating the numerical results (with support from a\ntheoretical approach) to edge lengths and gap widths of some micrometers, we\nconfirm the advantage of this regime to produce GBs with minimal roughness\nfaster than near-equilibrium conditions. This suggests an unexpected route\ntowards efficient growth of two-dimensional materials with smooth GBs."
    },
    {
        "anchor": "Validation of moment tensor potentials for fcc and bcc metals using\n  EXAFS spectra: Machine-learning potentials for materials, namely the moment tensor\npotentials (MTPs), were validated using experimental EXAFS spectra for the\nfirst time. The MTPs for four metals (bcc W and Mo, fcc Cu and Ni) were\nobtained by the active learning algorithm of fitting to the results of the\ncalculations using density functional theory (DFT). The MTP accuracy was\nassessed by comparing metal K-edge EXAFS spectra obtained experimentally and\ncomputed from the results of molecular dynamics (MD) simulations. The\nsensitivity of the method to various aspects of the MD and DFT models was\ndemonstrated using Ni as an example. Good agreement was found for W, Mo and Cu\nusing the recommended PAW pseudopotentials, whereas a more accurate\npseudopotential with 18 valence electrons was required for Ni to achieve a\nsimilar agreement. The use of EXAFS spectra allows one to estimate the MTP\nability in reproducing both average and dynamic atomic structures.",
        "positive": "Microscopic imaging of elastic deformation in diamond via in-situ stress\n  tensor sensors: The precise measurement of mechanical stress at the nanoscale is of\nfundamental and technological importance. In principle, all six independent\nvariables of the stress tensor, which describe the direction and magnitude of\ncompression/tension and shear stress in a solid, can be exploited to tune or\nenhance the properties of materials and devices. However, existing techniques\nto probe the local stress are generally incapable of measuring the entire\nstress tensor. Here, we make use of an ensemble of atomic-sized in-situ strain\nsensors in diamond (nitrogen-vacancy defects) to achieve spatial mapping of the\nfull stress tensor, with a sub-micrometer spatial resolution and a sensitivity\nof the order of 1 MPa (corresponding to a strain of less than $10^{-6}$). To\nillustrate the effectiveness and versatility of the technique, we apply it to a\nbroad range of experimental situations, including mapping the elastic stress\ninduced by localized implantation damage, nano-indents and scratches. In\naddition, we observe surprisingly large stress contributions from functional\nelectronic devices fabricated on the diamond, and also demonstrate sensitivity\nto deformations of materials in contact with the diamond. Our technique could\nenable in-situ measurements of the mechanical response of diamond\nnanostructures under various stimuli, with potential applications in strain\nengineering for diamond-based quantum technologies and in nanomechanical\nsensing for on-chip mass spectroscopy."
    },
    {
        "anchor": "Single Crystal Growth Tricks and Treats: Single crystal growth is a widely explored method of synthesizing materials\nin the solid state. The last few decades have seen significant improvements in\nthe techniques used to synthesize single crystals, but there has been\ncomparatively little discussion on ways to disseminate this knowledge. We aim\nto change that. Here we describe the principles of known single crystal growth\ntechniques as well as lesser-known variations that have assisted in the\noptimization of defect control in known materials. We offer a perspective on\nhow to think about these synthesis methods in a grand scheme. We consider the\ntemperature interdependence with the reaction time as well as ways to carry out\nsynthesis to scale up and address some outstanding synthesis challenges. We\nhope our descriptions will aid in technological advancements as well as further\ndevelopments to gain even better control over synthesis.",
        "positive": "Epitaxially strained SnTiO$_{3}$ at finite temperatures: Combining effective Hamiltonian and direct $ab$ $initio$ computation, we\nobtain the phase diagram of SnTiO$_{3}$ with respect to epitaxial strain and\ntemperature, demonstrating the complex features of the phase diagram and\nproviding insight into the epitaxially strained SnTiO$_{3}$, a presumably\nsimple perovskite. In the phase diagram, two triple points are found, which may\nbe exploited to to achieve high-performance piezoelectric effects. On the other\nhand, despite the inclusion of the degree of freedoms related to oxygen\noctahedron tilting, it is found that ferroelectric displacements dominate the\nstructural phases over the whole strain misfit range. Finally, it is shown that\nthe SnTiO$_{3}$ can be converted from hard to soft ferroelectrics with\nepitaxial strain."
    },
    {
        "anchor": "Overheated Topological Hall Effect: The topological Hall effect (THE) originates from the real-space Berry phase\nthat an electron gains when its spin follows the spatially varying non-trivial\nmagnetization textures, such as skyrmions. Such topologically protected\nmagnetization textures can provide great potential for information storage and\nprocessing. Since directly imaging the skyrmions or detecting the magnetic\ndiffraction of skyrmion lattice are significantly more challenging than\nconducting Hall measurements, THE has been widely used to attest the presence\nof skyrmions. However, the key feature of THE, namely the bump/dip in the Hall\nsignal is not sufficient proof of THE. Here, we use empirical numerical\nmodeling to demonstrate all possible THE-like signals that two anomalous Hall\neffect (AHE) signals with opposite signs can superpose. Besides the\nreproduction of many published results by the numerical model, we propose an\nexotic {\\lq THE\\rq} could, in principle, emerge with finely tuned two-channel\nAHE. The importance of the scrupulous re-examination of the THE observed in\nexperiments cannot be exaggerated.",
        "positive": "Study of electronic and magnetic properties and related x-ray absorption\n  spectroscopy of ultrathin Co films on BaTiO$_3$: We present a first-principles study of electronic and magnetic properties of\nthin Co films on a BaTiO$_3$(001) single crystal. The crystalline structure of\n1, 2, and 3 monolayer thick Co films was determined and served as input for\ncalculations of the electronic and magnetic properties of the films. The\nestimation of exchange constants indicates that the Co films are ferromagnetic\nwith a high critical temperature, which depends on the film thickness and the\ninterface geometry. In addition, we calculated x-ray absorption spectra,\nrelated magnetic circular dichroism (XMCD) and linear dichroism (XLD) of the Co\nL$_{2,3}$ edges as a function of Co film thickness and ferroelectric\npolarization of BaTiO$_3$. We found characteristic features, which depend\nstrongly on the magnetic properties and the structure of the film. While there\nis only a weak dependence of XMCD spectra on the ferroelectric polarization,\nthe XLD of the films is much more sensitive to the polarization switching,\nwhich could possibly be observed experimentally."
    },
    {
        "anchor": "Topology hierarchy of transition metal dichalcogenides built from\n  quantum spin Hall layers: The evolution of the physical properties of two-dimensional material from\nmonolayer limit to the bulk reveals unique consequences from dimension\nconfinement and provides a distinct tuning knob for applications. Monolayer\n1T'-phase transition metal dichalcogenides (1T'-TMDs) with ubiquitous quantum\nspin Hall (QSH) states are ideal two-dimensional building blocks of various\nthree-dimensional topological phases. However, the stacking geometry was\npreviously limited to the bulk 1T'-WTe2 type. Here, we introduce the novel\n2M-TMDs consisting of translationally stacked 1T'-monolayers as promising\nmaterial platforms with tunable inverted bandgaps and interlayer coupling. By\nperforming advanced polarization-dependent angle-resolved photoemission\nspectroscopy as well as first-principles calculations on the electronic\nstructure of 2M-TMDs, we revealed a topology hierarchy: 2M-WSe2, MoS2, and\nMoSe2 are weak topological insulators (WTIs), whereas 2M-WS2 is a strong\ntopological insulator (STI). Further demonstration of topological phase\ntransitions by tunning interlayer distance indicates that band inversion\namplitude and interlayer coupling jointly determine different topological\nstates in 2M-TMDs. We propose that 2M-TMDs are parent compounds of various\nexotic phases including topological superconductors and promise great\napplication potentials in quantum electronics due to their flexibility in\npatterning with two-dimensional materials.",
        "positive": "New Boys and Girls in Phosphorene Family from Gene Recombination:\n  Different from Parents, Excellent than Parents: Based on the crystal structures of the previously proposed low energy\nphosphorene allotropes {\\eta}-P and {\\theta}-P (Nano. Lett. 2015, 15, 3557), we\npropose five new structural stable phosphorene boys (XX-XY or XY-XY) and girls\n(XX-XX) through gene (XY from {\\eta}-P and XX from {\\theta}-P) recombination\nmethods. All of these five new phosphorene allotropes are obviously different\nfrom their parents, showing very different and fascinating two-dimensional\npatterns between each other. The dynamical stabilities of these phosphorene\nallotropes are confirmed positive and some of them are confirmed energetically\nmore favorable than their parents ({\\eta}-P and {\\theta}-P). Especially, the\nXX-XX type girl G1-P is confirmed energetically more favorable than all the\npreviously proposed phosphorene allotropes, including black phosphorene\n({\\alpha}-P, ACS Nano, 2014, 8, 4033) and blue phosphorene ({\\beta}-P, Phys.\nRev. Lett. 2014, 112, 176802), which is expected to be synthesized in future\nexperiment through vapor deposition. Our results show that such a new promising\nphosphorene allotrope G1-P is an excellent candidate for potential applications\nin nano-electronics according to its middle band gap about 1.58 eV from\nDFT-HSE06 calculation."
    },
    {
        "anchor": "High-temperature oxygen monolayer structures on W(110) revisited: Systematic studies of the two high-temperature monolayer oxygen structures\nthat exist on the (110) tungsten surface were performed using low-energy\nelectron microscopy and diffraction measurements. Our work questions the\ncommonly accepted interpretation from the literature that striped oxygen\nsuperstructures arise from alternating site-exchanged (S-E) domains. We\npostulate that the superstructures originate from a misfit between tungsten and\noxygen lattices while the striped appearance corresponds to a moir\\'e pattern.\nMoreover, we show that the two structures, indicated as 113- and 337-phases due\nto the characteristic directions of the respective moir\\'e patterns, differ\nconsiderably in their symmetry properties. This suggests that oxygen atoms in\nthe two overlayers occupy different adsorption sites on average. In particular,\nthe 113-phase features rotational domains that retain mirror symmetries with\nrespect to the [001] and [1-10] directions, whereas the 337-phase is\ncharacterized by the appearance of additional domains due to the breaking of\nthese symmetries. We propose structural models for both phases that\nconsistently explain their unusual properties and suggest a universal mechanism\nfor the thermal evolution of oxygen monolayer adsorbed on W(110).",
        "positive": "Why Some Interfaces Cannot be Sharp: A central goal of modern materials physics and nanoscience is control of\nmaterials and their interfaces to atomic dimensions. For interfaces between\npolar and non-polar layers, this goal is thwarted by a polar catastrophe that\nforces an interfacial reconstruction. In traditional semiconductors this\nreconstruction is achieved by an atomic disordering and stoichiometry change at\nthe interface, but in multivalent oxides a new option is available: if the\nelectrons can move, the atoms don`t have to. Using atomic-scale electron energy\nloss spectroscopy we find that there is a fundamental asymmetry between\nionically and electronically compensated interfaces, both in interfacial\nsharpness and carrier density. This suggests a general strategy to design sharp\ninterfaces, remove interfacial screening charges, control the band offset, and\nhence dramatically improving the performance of oxide devices."
    },
    {
        "anchor": "Ultrasonic preparation of mesoporous silica using pyridinium ionic\n  liquid: Mesoporous silica matrices have been prepared via classic acid catalyzed and\nsono-catalyzed sol-gel routes. Tetramethoxysilan (TMOS) and\nmethyl-trimethoxysilane (MTMS) were used as silica precursors, and\nN-butyl-3-methylpyridinium tetrafluoroborate ([bmPy][BF4]) was employed as\nco-solvent and pore template. The ionic liquid (IL) to silica mole ratio was\nvaried between 0.007 and 0.07. Nitrogen adsorption-desorption and small-angle\nneutron scattering measurements were used to characterize the obtained\nmaterials. The ionic liquid played the role of catalyst that affected the\nformation of the primary xerogel particles, and changed the porosity of the\nmaterials. Ultrasound treatment resulted in microstructure change on the level\nof the colloid particle aggregates. In comparison with IL containing xerogels,\nthe IL containing sonogels show increased pore diameter, bigger pore volumes\nand diminished surface areas.",
        "positive": "Charge Transport in Polycrystalline Graphene: Challenges and\n  Opportunities: Graphene has attracted significant interest both for exploring fundamental\nscience and for a wide range of technological applications. Chemical vapor\ndeposition (CVD) is currently the only working approach to grow graphene at\nwafer scale, which is required for industrial applications. Unfortunately, CVD\ngraphene is intrinsically polycrystalline, with pristine graphene grains\nstitched together by disordered grain boundaries, which can be either a\nblessing or a curse. On the one hand, grain boundaries are expected to degrade\nthe electrical and mechanical properties of polycrystalline graphene, rendering\nthe material undesirable for many applications. On the other hand, they exhibit\nan increased chemical reactivity, suggesting their potential application to\nsensing or as templates for synthesis of one-dimensional materials. Therefore,\nit is important to gain a deeper understanding of the structure and properties\nof graphene grain boundaries. Here, we review experimental progress on\nidentification and electrical and chemical characterization of graphene grain\nboundaries. We use numerical simulations and transport measurements to\ndemonstrate that electrical properties and chemical modification of graphene\ngrain boundaries are strongly correlated. This not only provides guidelines for\nthe improvement of graphene devices, but also opens a new research area of\nengineering graphene grain boundaries for highly sensitive electrobiochemical\ndevices."
    },
    {
        "anchor": "Bismuth and Antimony Based Oxyhalides and Chalcohalides as Potential\n  Optoelectronic Materials: In the last decade the ns$^2$ cations (e.g., Pb$^{2+}$ and Sn$^{2+}$) based\nhalides have emerged as one of the most exciting new classes of optoelectronic\nmaterials, as exemplified by for instance hybrid perovskite solar absorbers.\nThese materials not only exhibit unprecedented performance in some cases, but\nthey also appear to break new ground with their unexpected properties, such as\nextreme tolerance to defects. However, because of the relatively recent\nemergence of this class of materials, there remain many yet to be fully\nexplored compounds. Here we assess a series of bismuth/antimony oxyhalides and\nchalcohalides using consistent first principles methods to ascertain their\nproperties and obtain trends. Based on these calculations, we identify a subset\nconsisting of three types of compounds that may be promising as solar\nabsorbers, transparent conductors, and radiation detectors. Their electronic\nstructure, connection to the crystal geometry, and impact on band-edge\ndispersion and carrier effective mass are discussed.",
        "positive": "Finite size effects in a model for plasticity of amorphous composites: We discuss the plastic behavior of an amorphous matrix reinforced by hard\nparticles. A mesoscopic depinning-like model accounting for Eshelby elastic\ninteractions is implemented. Only the effect of a plastic disorder is\nconsidered. Numerical results show a complex size-dependence of the effective\nflow stress of the amorphous composite. In particular the departure from the\nmixing law shows opposite trends associated to the competing effects of the\nmatrix and the reinforcing particles respectively. The reinforcing mechanisms\nand their effects on localization are discussed. Plastic strain is shown to\ngradually concentrate on the weakest band of the system. This correlation of\nthe plastic behavior with the material structure is used to design a simple\nanalytical model. The latter nicely captures reinforcement size effects in\n$-(\\log N/N)^{1/2}$ observed numerically. Predictions of the effective flow\nstress accounting for further logarithmic corrections show a very good\nagreement with numerical results."
    },
    {
        "anchor": "The limits of the total crystal-field splittings: The crystal-fields causing $|J>$ electron states splittings of the same\nsecond moment $\\sigma^{2}$ can produce different total splittings $\\Delta E$\nmagnitudes. Based on the numerical data on crystal-field splittings for the\nrepresentative sets of crystal-field Hamiltonians ${\\cal H}_{\\rm\nCF}=\\sum_{k}\\sum_{q}B_{kq}C_{q}^{(k)}$ with fixed indexes either $k$ or $q$,\nthe potentials leading to the extreme $\\Delta E$ have been identified. For all\ncrystal-fields the admissible ranges $(\\Delta E_{min},\\Delta E_{max})$ have\nbeen found numerically for $1\\leq J\\leq 8$. The extreme splittings are reached\nin the crystal-fields for which ${\\cal H}_{\\rm CF}s$ are the definite\nsuperpositions of the $C_{q}^{(k)}$ components with different rank $k=2,4$ and\n6 and the same index $q$. Apart from few exceptions, the lower limits $\\Delta\nE_{min}$ occur in the axial fields of ${\\cal H}_{\\rm\nCF}(q=0)=B_{20}C_{0}^{(2)}+B_{40}C_{0}^{(4)}+B_{60}C_{0}^{(6)}$, whereas the\nupper limits $\\Delta E_{max}$ in the low symmetry fields of ${\\cal H}_{\\rm\nCF}(q=1)=B_{21}C_{1}^{(2)}+B_{41}C_{1}^{(4)}+B_{61}C_{1}^{(6)}$. Mixing the\n${\\cal H}_{\\rm CF}$ components with different $q$ yields a secondary effect and\ndoes not determine the extreme splittings. The admissible $\\Delta E_{min}$\nchanges with $J$ from $2.00\\sigma$ to $2.40\\sigma$, whereas the $\\Delta\nE_{max}$ from $2.00\\sigma$ to $4.10\\sigma$. The maximal gap $\\Delta\nE_{max}-\\Delta E_{min}=2.00\\sigma$ has been found for the states $|J=4>$. Not\nall the nominally allowed total splittings, preserving $\\sigma^{2}=const$\ncondition, are physically available, and in consequence not all virtual\nsplittings diagrams can be observed in real crystal-fields.",
        "positive": "Free Energy Driven Transfer of Charge in Dense Electrochemically Active\n  Monomolecular Films: The interest in monomolecular films as electric conductors arises from the\nsearch for innovative materials. The utility of non-covalently bonded films is\nlimited because they are mechanically unstable and consist of poorly connected\ndomains. Consequently, charge transfers in these films are limited to the\ndistances in the order of a micrometer. Here we show that a recently developed\ngas phase assembling method (Burtman, V., Zelichenok, A., Yitzchaik, S. (1999)\nAngewandte Chemie Inter. Ed. 38, 2041-2045.), which produces robust dense\nmonolayers of NTCDI covalently attached to the surface of silicon, allows one\nto overcome this scale limitation. These virtually insulating monolayers can be\nphoto-chemically populated with cation-radicals via ejection of electrons into\nthe semi-conducting base. The positive charges of cation-radicals can migrate\nas far as several millimeters within microseconds in a random walk fashion thus\ndemonstrating the macroscopic connectivity of the film. Since the charges exist\nas cation-radicals, which are potent oxidants, their migration is coupled to\ntransfer of the free energy of their reduction and is driven by the redox\npotential gradient. Reduction of cation-radicals by an anode converts this free\nenergy into electromotive force. We show how these films can be implemented in\nsolar energy conversion and basic time-resolved distance-controlled studies of\nsequences of ultra-fast electron transfers."
    },
    {
        "anchor": "Simulations of Trions and Biexcitons in Layered Hybrid Organic-Inorganic\n  Lead Halide Perovskites: Behaving like atomically-precise two-dimensional quantum wells with\nnon-negligible dielectric contrast, the layered HOIPs have strong electronic\ninteractions leading to tightly bound excitons with binding energies on the\norder of 500 meV. These strong interactions suggest the possibility of larger\nexcitonic complexes like trions and biexcitons, which are hard to study\nnumerically due to the complexity of the layered HOIPs. Here, we propose and\nparameterize a model Hamiltonian for excitonic complexes in layered HOIPs and\nwe study the correlated eigenfunctions of trions and biexcitons using a\ncombination of diffusion Monte Carlo and very large variational calculations\nwith explicitly correlated Gaussian basis functions. Binding energies and\nspatial structures of these complexes are presented as a function of the layer\nthickness. The trion and biexciton of the thinnest layered HOIP have binding\nenergies of 35 meV and 44 meV, respectively, whereas a single exfoliated layer\nis predicted to have trions and biexcitons with equal binding enegies of 48\nmeV. We compare our findings to available experimental data and to that of\nother quasi-two-dimensional materials.",
        "positive": "Resonant Magnetic X-ray Diffraction Study on the Triangular Lattice\n  Antiferromagnet GdPd2Al3: Resonant magnetic x-ray diffraction experiments were carried out on the\nstacked triangular lattice antiferromagnet GdPd2Al3. The experiments revealed\nan expected initial collinear c-axis order at TN1 followed by an additional\nin-plane order at TN2, while at the same time we found that the ground state is\na helically ordered state of a very long incommensurate period of approximately\n700A. The distribution of K-domains was highly anisotropic, and the domain with\nthe modulation vector normal to the surface of the crystal was ascendant.\nLow-field magnetization is discussed on the basis of the observed\nincommensurate magnetic structure."
    },
    {
        "anchor": "Real-Space Magnetic Imaging of the Multiferroic Spinels MnV2O4 and Mn3O4: Controlling multiferroic behavior in materials will enable the development of\na wide variety of technological applications. However, the exact mechanisms\ndriving multiferroic behavior are not well understood in most materials. Two\nsuch materials are the spinels MnV2O4 and Mn3O4, where mechanical strain is\nthought to play a role in determining magnetic behavior. Bulk studies of MnV2O4\nhave yielded conflicting and inconclusive results, due in part to the presence\nof mesoscale magnetic inhomogeneity, which complicates the interpretation of\nbulk measurements. To study the sub-micron-scale magnetic properties of\nMn-based spinel materials, we performed magnetic force microscopy (MFM) on\nMnV2O4 samples subject to different levels of mechanical strain. We also used a\ncrystal grain mapping technique to perform spatially registered MFM on Mn3O4.\nThese local investigations revealed 100-nm-scale \"stripe\" modulations in the\nmagnetic structure of both materials. In MnV2O4, the magnetization of these\nstripes is estimated to be Mz $\\approx$ 105 A/m, which is on the order of the\nsaturation magnetization reported previously. Cooling in a strong magnetic\nfield eliminated the stripe patterning only in the low-strain sample of MnV2O4.\nThe discovery of nanoscale magnetostructural inhomogeneity that is highly\nsusceptible to magnetic field control in these materials necessitates both a\nrevision of theoretical proposals and a reinterpretation of experimental data\nregarding the low-temperature phases and magnetic-field-tunable properties of\nthese Mn-based spinels.",
        "positive": "Biochars at the molecular level. Part 2 -- Development of realistic\n  molecular models of biochars: Biochars have been attracting renewed attention as economical and\nenvironmentally friendly carbon sequestration materials with a diverse range of\napplications. However, experimental developments may be limited by the lack of\nmolecular-level knowledge of the key interactions driving these applications.\nMolecular modelling techniques, such as molecular dynamics simulations, offer a\nsystematic and reproducible alternative and yield atomistic insights into\nphysicochemical processes, allowing the identification of adsorption mechanisms\nand, through this, informing and guiding experimental development. In this\nwork, on the basis of the critical assessment of the analytical techniques for\ncharacterisation of biochars and collation of a large volume of experimental\ndata, we develop molecular models of three woody biochar materials,\nrepresentative of those produced under low-, medium-, and high-temperature\ntreatments. We characterise these models, validating them against experimental\ndata, and share them with the research community. Furthermore, we detail our\niterative approach to the design of these biochar models, discuss what we have\nlearned about the relationship between biochar composition and its morphology,\nand finally share all of the building blocks used to create these biochar\nmodels. With this work, we hope to speed up the uptake of molecular dynamics\nsimulations for the study and development of biochar materials and, to this\nend, we distribute our easy-to-use surface-exposed biochar models ready for the\nadsorption studies."
    },
    {
        "anchor": "Topological chiral kagome lattice: Chirality, a fundamental structural property of crystals, can induce many\nunique topological quantum phenomena. In kagome lattice, unconventional\ntransports have been reported under tantalizing chiral charge order. Here, we\nshow how by deforming the kagome lattice to obtain a three-dimensional (3D)\nchiral kagome lattice in which the key band features of the non-chiral 2D\nkagome lattice - flat energy bands, van Hove singularities (VHSs), and\ndegeneracies - remain robust in both the $k_z$ = 0 and $\\pi$ planes in momentum\nspace. Given the handedness of our kagome lattice, degenerate momentum points\npossess quantized Chern numbers, ushering in the realization of Weyl fermions.\nOur 3D chiral kagome lattice surprisingly exhibits 1D behavior on its surface,\nwhere topological surface Fermi arc states connecting Weyl fermions are\ndispersive in one momentum direction and flat in the other direction. These 1D\nFermi arcs open up unique possibilities for generating unconventional non-local\ntransport phenomena at the interfaces of domains with different handedness, and\nthe associated enhanced conductance as the separation of the leads on the\nsurface is increased. Employing first-principles calculations, we investigate\nin-depth the electronic and phononic structures of representative materials\nwithin the ten space groups that can support topological chiral kagome\nlattices. Our study opens a new research direction that integrates the\nadvantages of structural chirality with those of a kagome lattice and thus\nprovides a new materials platform for exploring unique aspects of correlated\ntopological physics in chiral lattices.",
        "positive": "Structural and magnetic properties of ZnO:TM (TM: Co,Mn) nanopowders: We report on the structural and magnetic characterization of Co0.1Zn0.9O and\nMn0.1Zn0.9O nanopowders obtained by a soft chemistry route. We show that those\nsamples fired at low temperatures display a ferromagnetic interaction that can\nnot be attributed to the presence of impurities. A magnetic aging mechanism is\nobserved, reflecting the key role played by defects in the stabilization of\nferromagnetism in this kind of diluted magnetic semiconductors."
    },
    {
        "anchor": "An image processing pipeline for in-situ dynamic X-ray imaging of\n  directional solidification of metal alloys in thin cells: We present an image processing algorithm developed for quantitative analysis\nof directional solidification of metal alloys in thin cells using X-ray\nimaging. Our methodology allows to identify the fluid volume, fluid channels\nand cavities, and to separate them from the solidified structures. It also\nallows morphological analysis within the solid fraction, including automatic\ndecomposition into dominant grains by orientation and connectivity. In\naddition, the interplay between solidification and convection can be studied by\ncharacterizing convection plumes in the fluid, and solute concentrations above\nthe developing solidification front. The image filters used enable the\ndeveloped code (open-source) to work reliably even for single images with low\nsignal-to-noise ratio, low contrast-to-noise ratio, and low image resolution.\nThis is demonstrated by applying the code to several dynamic in situ X-ray\nimaging experiments with a solidifying gallium-indium alloy in a thin cell.\nGrain (and global) dendrite orientation statistics, convective plume\nparameterization, etc. can be obtained from the code output. The limitations of\nthe presented approach are also explained.",
        "positive": "KMC-MD Investigations of Hyperthermal Copper Deposition on Cu(111): Detailed KMC-MD (kinetic Monte Carlo-molecular dynamics) simulations of\nhyperthermal energy (10-100 eV) copper homoepitaxy have revealed a re-entrant\nlayer-by-layer growth mode at low temperatures (50K) and reasonable fluxes (1\nML/s). This growth mode is the result of atoms with hyperthermal kinetic\nenergies becoming inserted into islands when the impact site is near a step\nedge. The yield for atomic insertion as calculated with molecular dynamics near\n(111) step edges reaches a maxima near 18 eV. KMC-MD simulations of growing\nfilms and a minima in the RMS roughness as a function of energy near 25 eV. We\nfind that the RMS roughness saturates just beyond 0.5 ML of coverage in films\ngrown with energies greater than 25 eV due to the onset of adatom-vacancy\nformation near 20 eV. Adatom-vacancy pairs increase the island nuclei density\nand the step edge density which increases the number of sites available to\ninsert atoms. Smoothest growth in this regime is achieved by maximizing island\nand step edge densities, which consequently reverses the traditional roles of\ntemperature and flux: low temperatures and high fluxes produce the smoothest\nsurfaces in these films. Dramatic increases in island densities are found to\npersist at room temperature,where island densities increase an order of\nmagnitude from 20 to 150 eV."
    },
    {
        "anchor": "Avoiding the $H_c=0$ anomaly using FORC+ (expanded version of paper\n  GG-05, MMM-Intermag 2019): In conventional FORC (First Order Reversal Curve) analysis of a magnetic\nsystem, reversible and low-coercivity irreversible materials are treated as\nbeing qualitatively different: the FORC distribution shows low-coercivity\nmaterials but completely hides reversible (zero-coercivity) ones. This\ndistinction is artificial -- as the coercivity approaches zero, the physical\nproperties of an irreversible material change smoothly into those of a\nreversible material. We have developed a method (called FORC+, implemented in\nfree software at http://MagVis.org) for displaying the reversible properties of\na system (a reversible switching-field distribution, R-SFD) together with the\nirreversible ones (the usual FORC distribution), so that there is no sudden\ndiscontinuity in the display when the coercivity becomes zero. We will define a\n\"FORC+ dataset\" to include the usual FORC distribution, the R-SFD, the\nsaturation magnetization, and what we will call the \"lost hysteron\ndistribution\" (LHD) such that no information is lost -- the original FORC\ncurves can be exactly recovered from the FORC+ dataset. We also give some\nexamples of the application of FORC+ to real data -- it uses a novel\ncomplementary-color display that minimizes the need for smoothing. In systems\nwhich switch suddenly (thus having sharp structures in the FORC distribution)\ndirect display of un-smoothed raw data allows visualization of sharp structures\nthat would be washed out in a conventional smoothed FORC display. This is an\nexpanded version of paper GG-05, MMM-Intermag 2019, with a discrete derivation\nof the FORC distribution (Eq. 1) and an additional example (Fig. 7).",
        "positive": "High Efficiency Graphene Solar Cells by Chemical Doping: We demonstrate single layer graphene/n-Si Schottky junction solar cells that\nunder AM1.5 illumination exhibit a power conversion efficiency (PCE) of 8.6%.\nThis performance, achieved by doping the graphene with\nbis(trifluoromethanesulfonyl)amide, exceeds the native(undoped) device\nperformance by a factor of 4.5 and the best previously reported PCE in similar\ndevices by a factor of nearly 6. Current-voltage, capacitance-voltage and\nexternal quantum efficiency measurements show the enhancement to be due to the\ndoping induced shift in the graphene chemical potential which increases the\ngraphene carrier density (decreasing the cell series resistance) and increases\nthe built-in potential."
    },
    {
        "anchor": "Cr doped III-V nitrides: potential candidates for spintronics: Studies of Cr-doped III-V nitrides, dilute magnetic alloys, in the\nzinc-blende crystal structure are presented. The objective of the work is to\ninvestigate half-metallicity in Al(0.75)Cr(0.25)N, Ga(0.75)Cr(0.25)N and\nIn(0.75)Cr(0.25)N for their possible application in the spin based electronic\ndevices. The calculated spin polarized band structures, electronic properties\nand magnetic properties of these compounds reveal that Al0.75Cr0.25N and\nGa0.75Cr0.25N are half-metallic dilute magnetic semiconductors while\nIn0.75Cr0.25N is metallic in nature. The present theoretical predictions\nprovide evidence that some Cr doped III-V nitrides can be used in spintronics\ndevices.",
        "positive": "Three-dimensional magnetic flux-closure patterns in mesoscopic Fe\n  islands: We have investigated three-dimensional magnetization structures in numerous\nmesoscopic Fe/Mo(110) islands by means of x-ray magnetic circular dichroism\ncombined with photoemission electron microscopy (XMCD-PEEM). The particles are\nepitaxial islands with an elongated hexagonal shape with length of up to 2.5\nmicrometer and thickness of up to 250 nm. The XMCD-PEEM studies reveal\nasymmetric magnetization distributions at the surface of these particles.\nMicromagnetic simulations are in excellent agreement with the observed magnetic\nstructures and provide information on the internal structure of the\nmagnetization which is not accessible in the experiment. It is shown that the\nmagnetization is influenced mostly by the particle size and thickness rather\nthan by the details of its shape. Hence, these hexagonal samples can be\nregarded as model systems for the study of the magnetization in thick,\nmesoscopic ferromagnets."
    },
    {
        "anchor": "Scalable production of single 2D van der Waals layers through atomic\n  layer deposition: Bilayer silica on metal foils and films: The self-limiting nature of atomic layer deposition (ALD) makes it an\nappealing option for growing single layers of two-dimensional van der Waals\n(2D-VDW) materials. In this paper it is demonstrated that a single layer of a\n2D-VDW form of SiO2 can be grown by ALD on Au and Pd polycrystalline foils and\nepitaxial films. The silica was deposited by two cycles of bis (diethylamino)\nsilane and oxygen plasma exposure at 525 K. Initial deposition produced a\nthree-dimensionally disordered silica layer; however, subsequent annealing\nabove 950 K drove a structural rearrangement resulting in 2D-VDW; this\nannealing could be performed at ambient pressure. Surface spectra recorded\nafter annealing indicated that the two ALD cycles yielded close to the silica\ncoverage obtained for 2D-VDW silica prepared by precision SiO deposition in\nultra-high vacuum. Analysis of ALD-grown 2D-VDW silica on a Pd(111) film\nrevealed the co-existence of amorphous and incommensurate crystalline 2D\nphases. In contrast, ALD growth on Au(111) films produced predominantly the\namorphous phase while SiO deposition in UHV led to only the crystalline phase,\nsuggesting that the choice of Si source can enable phase control.",
        "positive": "Adiabatic transformation as a search tool for new topological\n  insulators: distorted ternary Li$_2$AgSb-class semiconductors and related\n  compounds: We demonstrate that first-principles based adiabatic continuation approach is\na very powerful and efficient tool for constructing topological phase diagrams\nand locating non-trivial topological insulator materials. Using this technique,\nwe predict that the ternary intermetallic series Li$_2M'X$ where $M'$=Cu, Ag,\nAu, or Cd, and $X$=Sb, Bi, or Sn, hosts a number of topological insulators with\nremarkable functional variants and tunability. We also predict that several\nIII-V semimetallic compounds are topologically non-trivial. We construct a\ntopological phase diagram in the parameter space of the atomic numbers of atoms\nin Li$_2M'X$ compounds, which places a large number of topological materials\npresented in this work as well as in earlier studies within a single unified\ntopological framework. Our results demonstrate the efficacy of adiabatic\ncontinuation as a useful tool for exploring topologically nontrivial alloying\nsystems and for identifying new topological insulators even when the underlying\nlattice does not possess inversion symmetry, and the approaches based on parity\nanalysis are not viable."
    },
    {
        "anchor": "Shaping single walled nanotubes: We show that electron irradiation in a dedicated scanning transmission\nmicroscope can be used as a nano-electron-lithography technique allowing the\ncontrolled reshaping of single walled carbon and boron nitride nanotubes. The\nrequired irradiation conditions have been optimised on the basis of total\nknock-on cross sections calculated within density functional based methods. It\nis then possible to induce morphological modifications, such as a change of the\ntube chirality, by removing severals tens of atoms with a nanometrical spatial\nresolution. These irradiation techniques could open new opportunities for\nnano-engeneering a large variety of nanostructured materials.",
        "positive": "Study on the Fermi level of microstructured Silicon with impurities\n  introduced by chalcogenides and their affect on solar cell efficiency: Microstructured Silicon, which is obtained by irradiating the surface of a\nSilicon wafer with femtosecond laser pulses under certain circumstances, has\nunusual optical properties such as the strong absorption of light with\nwavelength from 0.25{\\mu}m to 17{\\mu}m. So it holds great promise in the\nintermediate band solar cell (IBSC). Some articles have discussed the\nelectronic structure associating with simple substitutional impurities in\nSilicon introduced by chalcogenides. And on this basis, after high temperature\nannealing treatment, we establish the mode of impurity levels of\nmicrostructured Silicon introduced by sulfur and oxygen. Using generalized\nstatistics of multi-level,we analyze the probability of electronic in all local\nenergy levels and the relationship among Fermi level, temperature and the\ndensity of impurities. Then the theoretical conversion efficiency of the\ncorresponding IBSC is discussed with the Detailed Balance Theory. And the issue\nof making high efficiency solar cells based on femtosecond laser\nmicrostructured Silicon is discussed in detail."
    },
    {
        "anchor": "Multiferroic nature of charge-ordered rare earth manganites: Charge-ordered rare earth manganites Nd0.5Ca0.5MnO3, La0.25Nd0.25Ca0.5MnO3,\nPr0.7Ca0.3MnO3 and Pr0.6Ca0.4MnO3 are found to exhibit dielectric constant\nanomalies around the charge-ordering or the magnetic transition temperatures.\nMagnetic fields have a marked effect on the dielectric properties, indicating\nthe presence of coupling between the magnetic and electrical order parameters.\nThe observation of magnetoferroelectricity in these manganites is in accord\nwith the recent theoretical predictions of Khomskii and coworkers.",
        "positive": "Electron Emission from Diamondoids: A Diffusion Quantum Monte Carlo\n  Study: We present density-functional theory (DFT) and quantum Monte Carlo (QMC)\ncalculations designed to resolve experimental and theoretical controversies\nover the optical properties of H-terminated C nanoparticles (diamondoids). The\nQMC results follow the trends of well-converged plane-wave DFT calculations for\nthe size dependence of the optical gap, but they predict gaps that are 1-2 eV\nhigher. They confirm that quantum confinement effects disappear in diamondoids\nlarger than 1 nm, which have gaps below that of bulk diamond. Our QMC\ncalculations predict a small exciton binding energy and a negative electron\naffinity (NEA) for diamondoids up to 1 nm, resulting from the delocalized\nnature of the lowest unoccupied molecular orbital. The NEA suggests a range of\npossible applications of diamondoids as low-voltage electron emitters."
    },
    {
        "anchor": "Multiple Localized States and Magnetic Orderings in Partially Open\n  Zigzag Carbon Nanotube Superlattices: An Ab Initio Study: Using first-principles calculations, we examine the electronic and magnetic\nproperties of partially open zigzag carbon nanotube (CNT) superlattices. It is\nfound that depending on their opening degree, these superlattices can exhibit\nmultiple localized states around the Fermi energy. More importantly, some\nelectronic states confined in some parts of the structure even have special\nmagnetic orderings. We demonstrate that, as a proof of principle, some\npartially open zigzag CNT superlattices are by themselves giant (100%)\nmagnetoresistive devices. Furthermore, the localized(and spin-polarized) states\nas well as the band gaps of the superlattices could be further modulated by\nexternal electric fields perpendicular to the tube axis, and a bias voltage\nalong the tube axis may be used to control the conductance of two spin states.\nWe believe that these results will open the way to the production of novel\nnanoscale electronic and spintronic devices.",
        "positive": "Synthetic Multiferroic Interconnects for Magnetic Logic Circuits: In this work, we consider the possibility of using synthetic multiferroics\ncomprising piezoelectric and magnetostrictive materials as an interconnect for\nnano magnetic logic circuits. The proposed interconnect resembles a parallel\nplate capacitor filled with a piezoelectric, where one of the plates is made of\na magnetoelastic material. The operation of the interconnect is based on the\neffect of stress-mediated anisotropy modulation, where an electric field\napplied across the piezoelectric material produces stress, which, in turn,\naffects the anisotropy field in the magnetostrictive material. We present the\nresults of numerical modeling illustrating signal propagation through the\ninterconnect. The model combines electric and magnetic parts, where the\nelectric part describes the distribution of an electric field through the\npiezoelectric and the magnetic part describes the change of magnetization in\nthe magnetoelastic layer. The model is based on the Landau-Lifshitz-Gilbert\nequation with the electric field dependent anisotropy term included. The\nutilization of the electro-magnetic coupling makes it possible to amplify\nmagnetic signal during its propagation via energy conversion from the electric\nto magnetic domains. Potentially, synthetic multiferroic interconnects can be\nimplemented in a variety of spin-based devices ensuring reliable and low-energy\nconsuming data transmission. According to the estimates, the group velocity of\nmagnetic signals may be up to 100 km/s with energy dissipation less than aJ per\nbit per 100nm. The fundamental limits and practical shortcoming of the proposed\napproach are also discussed."
    },
    {
        "anchor": "Combined hybrid functional and DFT+$U$ calculations for metal\n  chalcogenides: In the density-functional studies of materials with localized electronic\nstates, the local/semilocal exchange-correlation functionals are often either\ncombined with a Hubbard parameter $U$ as in the LDA+$U$ method or mixed with a\nfraction of exactly computed (Fock) exchange energy yielding a hybrid\nfunctional. Although some inaccuracies of the semilocal density approximations\nare thus fixed to a certain extent, the improvements are not sufficient to make\nthe predictions agree with the experimental data. Here we put forward the\nperspective that the hybrid functional scheme and the LDA+$U$ method should be\ntreated as complementary, and propose to combine the range-separated (HSE)\nhybrid functional with the Hubbard $U$. We thus present a variety of HSE+$U$\ncalculations for a set of II-VI semiconductors, consisting of zinc and cadmium\nmonochalcogenides, along with comparison to the experimental data. Our findings\nimply that an optimal value $U^\\ast$ of the Hubbard parameter could be\ndetermined, which ensures that the HSE+$U^\\ast$ calculation reproduces the\nexperimental band gap. It is shown that an improved description not only of the\nelectronic structure but also of the crystal structure and energetics is\nobtained by adding the $U^\\ast$ term to the HSE functional, proving the utility\nof HSE+$U^\\ast$ approach in modeling semiconductors with localized electronic\nstates.",
        "positive": "Modified embedded-atom method interatomic potentials for the Mg-Al alloy\n  system: We developed new modified embedded-atom method (MEAM) interatomic potentials\nfor the Mg-Al alloy system using a first-principles method based on density\nfunctional theory (DFT). The materials parameters, such as the cohesive energy,\nequilibrium atomic volume, and bulk modulus, were used to determine the MEAM\nparameters. Face-centered cubic, hexagonal close packed, and cubic rock salt\nstructures were used as the reference structures for Al, Mg, and MgAl,\nrespectively. The applicability of the new MEAM potentials to atomistic\nsimulations for investigating Mg-Al alloys was demonstrated by performing\nsimulations on Mg and Al atoms in a variety of geometries. The new MEAM\npotentials were used to calculate the adsorption energies of Al and Mg atoms on\nAl (111) and Mg (0001) surfaces. The formation energies and geometries of\nvarious point defects, such as vacancies, interstitial defects and\nsubstitutional defects, were also calculated. We found that the new MEAM\npotentials give a better overall agreement with DFT calculations and\nexperiments when compared against the previously published MEAM potentials."
    },
    {
        "anchor": "Stochastic model and kinetic Monte Carlo simulation of solute\n  interactions with stationary and moving grain boundaries. II. Application to\n  two-dimensional systems: In Part I of this work, we proposed a stochastic model describing solute\ninteractions with stationary and moving grain boundaries (GBs) and applied it\nto planar GBs in 1D systems. The model reproduces nonlinear GB dynamics, solute\nsaturation in the segregation atmosphere, and all basic features of the solute\ndrag effect. Part II of this work extends the model to 2D GBs represented by\nsolid-on-solid interfaces. The model predicts a GB roughening transition in\nstationary GBs and reversible dynamic roughening in moving GBs. The impacts of\nthe GB roughening on GB migration mechanisms, GB mobility, and the solute drag\nare studied in detail. The threshold effect in GB dynamics is explained by the\ndynamic roughening transition, which is amplified in the presence of solute\nsegregation. The simulation results are compared with the classical models by\nCahn and L\\\"ucke-St\\\"uwe and previous computer simulations.",
        "positive": "Probing charge pumping and relaxation of the chiral anomaly in a Dirac\n  semimetal: The linear band crossings of 3D Dirac and Weyl semimetals are characterized\nby a charge chirality, the parallel or anti-parallel locking of electron spin\nto its momentum. Such materials are believed to exhibit a ${\\bf E} \\cdot {\\bf\nB}$ chiral magnetic effect that is associated with the near conservation of\nchiral charge. Here, we use magneto-terahertz spectroscopy to study epitaxial\nCd$_3$As$_2$ films and extract their conductivities $\\sigma(\\omega)$ as a\nfunction of ${\\bf E} \\cdot {\\bf B}$. As field is applied, we observe a\nremarkably sharp Drude response that rises out of the broader background. Its\nappearance is a definitive signature of a new transport channel and consistent\nwith the chiral response, with its spectral weight a measure of the net chiral\ncharge and width a measure of the scattering rate between chiral species. The\nfield independence of the chiral relaxation establishes that it is set by the\napproximate conservation of the isospin that labels the crystalline point-group\nrepresentations."
    },
    {
        "anchor": "Growing low-dimensional supramolecular crystals directly from 3D\n  particles: We show that one-dimensional (1D) nanostructures and two-dimensional (2D)\nsupramolecular crystals of organic semiconductors can be grown on substrates\nunder ambient conditions directly from three-dimensional (3D) organic crystals.\nThe approach does not require dissolving, melting or evaporating of the source\ncrystals and is based on the Organic Solid-Solid Wetting Deposition (OSWD). We\nexemplify our approach by the pigment quinacridone (QAC). Scanning Tunnelling\nMicroscopy (STM) investigations show that the structures of the resulting 2D\ncrystals are similar to the chain arrangement of the alpha and beta QAC\npolymorphs and are independent of the 3D source crystal polymorph (gamma).\nFurthermore, distinct 1D chains can be produced systematically.",
        "positive": "Recent Progress in the Computational Many-Body Theory of Metal Surfaces: In this article we describe recent progress in the computational many-body\ntheory of metal surfaces, and focus on current techniques beyond the\nlocal-density approximation of density-functional theory. We overview various\napplications to ground and excited states. We discuss the exchange-correlation\nhole, the surface energy, and the work function of jellium surfaces, as\nobtained within the random-phase approximation, a time-dependent\ndensity-functional approach, and quantum Monte Carlo methods. We also present a\nsurvey of recent quasiparticle calculations of unoccupied states at both\njellium and real surfaces."
    },
    {
        "anchor": "Accurate Determination of the Band-Gap Energy of the Rare-Earth Niobate\n  Series: In this work, we report diffuse reflectivity measurements in InNbO4, ScNbO4,\nYNbO4, and eight different rare-earth niobates. From a comparison with the\nestablished values of the band gap of InNbO4 and ScNbO4, we have found that the\nbroadly used Tauc plot analysis leads to erroneous estimates of the band-gap\nenergy of niobates. In contrast, accurate results are obtained considering\nexcitonic contributions using the Elliot-Toyozawa model. We have found that\nYNbO4 and the rare-earth niobates are wide band-gap materials. The band-gap\nenergy is 3.25 eV for CeNbO4, 4.35 eV for LaNbO4, 4.5 eV for YNbO4, and 4.73 -\n4.93 eV for SmNbO4, EuNbO4, GdNbO4, DyNbO4, HoNbO4, and YbNbO4. An explanation\nfor the obtained results will be presented. The fact that the band-gap energy\nis nearly not affected by the rare-earth substitution from SmNbO4 to YbNbO4 and\nthe circumstance that these are the compounds with the largest band gap are a\nconsequence of the fact that the band structure near the Fermi level originates\nmainly from Nb 4d and O 2p orbitals. We hypothesize that YNbO4, CeVO4, and\nLaNbO4 have smaller band gaps because of the contribution from rare-earth atom\n4d or 5f states to the states near the Fermi level.",
        "positive": "Finite-temperature surface elasticity of crystalline solids: Surface energies and surface elasticity largely affect the mechanical\nresponse of nanostructures as well as the physical phenomenon associated with\nsurfaces such as evaporation and adsorption. Studying surface energies at\nfinite temperatures is therefore of immense interest for nanoscale\napplications. However, calculating surface energies and derived quantities from\natomistic ensembles is usually limited to zero temperature or involve\ncumbersome thermodynamic integration techniques at finite temperature. Here, we\nillustrate a technique to identify the energy and elastic properties of\nsurfaces of solids at non-zero temperature based on a Gaussian phase packets\n(GPP) approach (which in the isothermal limit coincides with a maximum-entropy\nformulation). Using this setup, we investigate the effect of temperature on the\nsurface properties of different crystal faces for six pure metals -- copper,\nnickel, alumimum, iron, tungsten and vanadium -- thus covering both FCC and BCC\nlattice structures. While the obtained surface energies and stresses usually\nshow a decreasing trend with increasing temperature, the elastic constants do\nnot show such a consistent trend across the different materials and are quite\nsensitive to temperature changes. Validation is performed by comparing the\nobtained surface energy densities of selected BCC and FCC materials to those\ncalculated via molecular dynamics."
    },
    {
        "anchor": "Unraveling a Structure-Property Relationship for Methylammonium Lead/Tin\n  Trihalide Organic-Inorganic Hybrid Perovskite Solar Cells: The esoteric importance of intermolecular hydrogen bonding interaction to\ndesign novel methylammonium trihalide organic-inorganic hybrid perovskite solar\ncell materials is uncovered, establishing the unified structure-property\nrelationship between the calculated Y...H intermolecular hydrogen bonding\ndistance and the experimentally reported onset of optical absorption (bandgap)\nfor the bulk geometries of the ten-membered methylammonium lead trihalide\n(CH3NH3PbY3) perovskite solar cell series, where Y = X (X = Cl, Br, I) and the\nmixed halogen derivatives. The same relationship is also revealed for the\nten-membered methylammonium tin trihalide (CH3NH3SnY3) perovskite solar cell\nseries. The relationship unequivocally demonstrates that the intermolecular\nhydrogen bonding interaction does not only enforce the aforesaid materials to\nbecome functional for optoelectronic application, but also serve as an asset to\npartially address the often debated question what is the role played by the\nCH3NH3+ organic cation.",
        "positive": "Second order kinetic Kohn-Sham lattice model: In this work we introduce a new semi-implicit second order correction scheme\nto the kinetic Kohn-Sham lattice model. The new approach is validated by\nperforming realistic exchange-correlation energy calculations of atoms and\ndimers of the first two rows of the periodic table finding good agreement with\nthe expected values. Additionally we simulate the ethane molecule where we\nrecover the bond lengths and compare the results with standard methods.\nFinally, we discuss the current applicability of pseudopotentials within the\nlattice kinetic Kohn-Sham approach."
    },
    {
        "anchor": "Structural stability, electronic band structure, and optoelectronic\n  properties of quaternary chalcogenide CuZn2MS4 (M =In and Ga) compounds via\n  first principles: Quaternary chalcogenide compositions have been broadly explored due to their\npromising potential for various optoelectronic applications. The band\nstructure, density of states and optical properties of CuZn2InS4 and CuZn2GaS4\nfor kesterite and stannite structures were studied with full potential\naugmented plane wave method (FP-LAPW) via Wien2k code. The total energy in\nequilibrium was calculated for different possible crystal structures and their\nphase stability, and transitions with p-d orbitals were analyzed. The\nabsorption coefficient, dielectric function, and refractive index of these\nmaterials were also explored within a broad range of energy. We compared the\ncalculated band gap values with available experimental results.",
        "positive": "Electronic and phononic properties of cinnabar: ab initio calculations\n  and some experimental results: We report ab initio calculations of the electronic band structure, the\ncorresponding optical spectra, and the phonon dispersion relations of trigonal\nalpha-HgS (cinnabar). The calculated dielectric functions are compared with\nunpublished optical measurements by Zallen and coworkers. The phonon dispersion\nrelations are used to calculate the temperature and isotopic mass dependence of\nthe specific heat which has been compared with experimental data obtained on\nsamples with the natural isotope abundances of the elements Hg and S (natural\nminerals and vapor phase grown samples) and on samples prepared from isotope\nenriched elements by vapor phase transport. Comparison of the calculated\nvibrational frequencies with Raman and ir data is also presented. Contrary to\nthe case of cubic beta-HgS (metacinnabar), the spin-orbit splitting of the top\nvalence bands at the Gamma-point of the Brillouin zone (Delta_0) is positive,\nbecause of a smaller admixture of 5d core electrons of Hg. Calculations of the\nlattice parameters, and the pressure dependence of Delta_0 and the\ncorresponding direct gap E_0~2eV are also presented. The lowest absorption edge\nis confirmed to be indirect."
    },
    {
        "anchor": "Incorporating quasiparticle and excitonic properties into material\n  discovery: In recent years, GW-BSE has been proven to be extremely successful in\nstudying the quasiparticle (QP) bandstructures and excitonic effects in the\noptical properties of materials. However, the massive computational cost\nassociated with such calculations restricts their applicability in\nhigh-throughput material discovery studies. Recently, we developed a Python\nworkflow package, $py$GWBSE, to perform high-throughput GW-BSE simulations. In\nthis work, using $py$GWBSE we create a database of various QP properties and\nexcitonic properties of over 350 chemically and structurally diverse materials.\nDespite the relatively small size of the dataset, we obtain highly accurate\nsupervised machine learning (ML) models via the dataset. The models predict the\nquasiparticle gap with an RMSE of 0.36 eV, exciton binding energies of\nmaterials with an RMSE of 0.29 eV, and classify materials as high or low\nexcitonic binding energy materials with classification accuracy of 90%. We\nexemplify the application of these ML models in the discovery of 159\nvisible-light and 203 ultraviolet-light photoabsorber materials utilizing the\nMaterials Project database.",
        "positive": "Chemical bonding in chalcogenides: the concept of multi-centre\n  hyperbonding: The precise nature of chemical-bonding interactions in amorphous, and\ncrystalline, chalcogenides is still unclear due to the complexity arising from\nthe delocalization of bonding, and non-bonding, electrons. Although an\nincreasing degree of electron delocalization for elements down a column of the\nperiodic table is widely recognized, its influence on chemical-bonding\ninteractions, and on consequent material properties, of chalcogenides has not\npreviously been comprehensively understood from an atomistic point of view.\nHere, we provide a chemical-bonding framework for understanding the behaviour\nof chalcogenides (and, in principle, other lone-pair materials) by studying\nprototypical Telluride non-volatile-memory, 'phase-change' materials (PCMs),\nand related chalcogenide compounds, via density-functional-theory,\nmolecular-dynamics (DFT-MD) simulations. Identification of the presence of\npreviously unconsidered multi-centre 'hyperbonding'\n(lone-pair-antibonding-orbital) interactions elucidates not only the origin of\nvarious material properties, and their contrast in magnitude between amorphous\nand crystalline phases, but also the very similar chemical-bonding nature\nbetween crystalline PCMs and one of the bonding subgroups (with the same bond\nlength) found in amorphous PCMs, in marked contrast to existing viewpoints. The\nstructure-property relationship established from this new bonding-interaction\nperspective will help in designing improved chalcogenide materials for diverse\napplications, based on a fundamental chemical-bonding point of view."
    },
    {
        "anchor": "Experimental corroboration of the Mulheran-Blackman explanation of the\n  scale invariance in thin film growth: the case of InAs quantum dots on\n  GaAs(001): Mulheran and Blackman have provided a simple and clear explanation of the\nscale invariance of the island size distribution at the early stage of film\ngrowth [Phil. Mag. Lett. 72, 55 (1995)]. Their theory is centered on the\nconcept of capture zone properly identified by Voronoi cell. Here we\nsubstantiate experimentally their theory by studying the scale invariance of\nInAs quantum dots (QDs) forming on GaAs(001) substrate. In particular, we show\nthat the volume distributions of QDs well overlap the corrisponding\nexperimental distributions of the Voronoi-cell areas. The interplay between the\nexperimental data and the numerical simulations allowed us to determine the\nspatial correlation length among QDs.",
        "positive": "A method for measuring the nonlinear response in dielectric spectroscopy\n  through third harmonics detection: We present a high sensitivity method allowing the measurement of the non\nlinear dielectric susceptibility of an insulating material at finite frequency.\nIt has been developped for the study of dynamic heterogeneities in supercooled\nliquids using dielectric spectroscopy at frequencies 0.05 Hz < f < 30000 Hz .\nIt relies on the measurement of the third harmonics component of the current\nflowing out of a capacitor. We first show that standard laboratory electronics\n(amplifiers and voltage sources) nonlinearities lead to limits on the third\nharmonics measurements that preclude reaching the level needed by our physical\ngoal, a ratio of the third harmonics to the fundamental signal about 7 orders\nof magnitude lower than 1. We show that reaching such a sensitivity needs a\nmethod able to get rid of the nonlinear contributions both of the measuring\ndevice (lock-in amplifier) and of the excitation voltage source. A bridge using\ntwo sources fulfills only the first of these two requirements, but allows to\nmeasure the nonlinearities of the sources. Our final method is based on a\nbridge with two plane capacitors characterized by different dielectric layer\nthicknesses. It gets rid of the source and amplifier nonlinearities because in\nspite of a strong frequency dependence of the capacitors impedance, it is\nequilibrated at any frequency. We present the first measurements of the\nphysical nonlinear response using our method. Two extensions of the method are\nsuggested."
    },
    {
        "anchor": "Wetting layer thickness and early evolution of epitaxially strained thin\n  films: We propose a physical model which explains the existence of finite thickness\nwetting layers in epitaxially strained films. The finite wetting layer is shown\nto be stable due to the variation of the non-linear elastic free energy with\nfilm thickness. We show that anisotropic surface tension gives rise to a\nmetastable enlarged wetting layer. The perturbation amplitude needed to\ndestabilize this wetting layer decreases with increasing lattice mismatch. We\nobserve the development of faceted islands in unstable films.",
        "positive": "Correlation between spin state and activity for hydrogen evolution: Spin plays a key role in physical and chemical reactions, such as oxygen\nevolution and hydrogen evolution reactions (OER/HER); but the spin-activity\ncorrelation has remained unclear. Based on a transition metal (TM)-doped PtN2\nmonolayer model with a well-defined spin center as adsorption site, we here\nreveal that only active spin state can enhance the strength of hydrogen\nadsorption, while inert spin state offers very little influence. Specifically,\nthe unpaired electron along the out-of-plane direction such as in dZ2 orbital,\nacting as an active spin state, will strongly hybridize with hydrogen,\nresulting in enhanced hydrogen binding energy because dZ2 orbital is just\nenough to accommodate two electrons to form a bonding orbital. While the\nin-plane unpaired electron such as in dX2-Y2 orbital, plays a negligible role\nin adsorbing hydrogen atom. This is verified by a series of single atom\ncatalysts comprising of PtN2 monolayer by replacing Pt atom with a TM (Fe, Co,\nNi, Ru, Rh, Pd, Os, or Ir) atom, or subsequent adsorbing a Cl atom. One of the\nmost promising materials is Pd@PtN2-Cl that offers superior HER activity, even\nbetter than pure Pt. This work uncovers the nature of spin-activity\ncorrelation, thus paving the way for the design of high-performance catalysts\nthrough spin-engineering."
    },
    {
        "anchor": "Investigating and understanding the effects of multiple femtosecond\n  laser scans on the surface topography of metallic specimens: The majority of studies performed on the formation of surface features by\nfemtosecond laser radiation focuses on single scan procedures, i.e. solely\nmanipulating the laser beam once over the target area to fabricate different\nsurface topographies. In this work, the effect of scanning stainless steel 304\nmultiple times with femtosecond laser pulses is thoroughly investigated over a\nwide range of fluences. The resultant laser-induced surface topographies can be\ncategorized into two different regimes. In the low fluence regime\n$(F_{{\\Sigma}line,max} < 130 ~J/cm^2)$, ellipsoidal cones (randomly distributed\nsurface protrusions covered by several layers of nanoparticles) are formed.\nBased on chemical, crystallographic, and topographical analyses, we conclude\nthat these ellipsoidal cones are composed of unablated steel whose conical\ngeometry offers a significant degree of fluence reduction (35-52%). Therefore,\nthe rest of the irradiated area is preferentially ablated at a higher rate than\nthe ellipsoidal cones. The second, or high fluence regime\n$(F_{{\\Sigma}line,max} > 130~ J/cm^2)$ consists of laser-induced surface\npatterns such as columnar and chaotic structures. Here, the surface topography\nshowed little to no change even when the target was scanned repeatedly. This is\nin stark contrast to the ellipsoidal cones in the first regime, which evolve\nand grow continuously as more laser passes are applied.",
        "positive": "Infrared phonon activity in pristine graphite: We study experimentally and theoretically the Fano-shaped phonon peak at 1590\ncm$^{-1}$ (0.2 eV) in the in-plane optical conductivity of pristine graphite.\nWe show that the anomalously large spectral weight and the Fano asymmetry of\nthe peak can be qualitatively accounted for by a charged-phonon theory. A\ncrucial role in this context is played by the particle-hole asymmetry of the\nelectronic $\\pi$-bands."
    },
    {
        "anchor": "Magnetic properties of nanoparticles compacts with controlled broadening\n  of the particle size distribution: Binary random compacts with different proportions of small (volume V) and\nlarge (volume 2V) bare maghemite nanoparticles (NPs) are used to investigate\nthe effect of controllably broadening the particle size distribution on the\nmagnetic properties of magnetic NP assemblies with strong dipolar interaction.\nA series of eight random mixtures of highly uniform 9.0 and 11.5 nm diameter\nmaghemite particles prepared by thermal decomposition are studied. In spite of\nseverely broadened size distributions in the mixed samples, well defined\nsuperspin glass transition temperatures are observed across the series, their\nvalues increasing linearly with the weight fraction of large particles.",
        "positive": "Peculiar band geometry induced giant shift current in ferroelectric SnTe\n  monolayer: The bulk photovoltaic effect (BPVE) refers to the phenomenon of generating\nphotocurrent or photovoltage in homogeneous noncentrosymmetric materials under\nillumination, and the intrinsic contribution to the BPVE is known as the shift\ncurrent effect. We calculate the shift current conductivities of the\nferroelectric SnTe monolayer using first-principles methods. We find that the\nmonolayer SnTe has giant shift-current conductivity near the valley points.\nMore remarkably, the linear optical absorption coefficient at this energy is\nvery small, and therefore leads to an enormous Glass coefficient that is four\norders of magnitude larger than that of BaTiO$_3$. The unusual shift-current\neffects are further investigated using a three-band model. We find that the\ngiant shift current conductivities and Glass coefficient are induced by the\nnontrivial energy band geometries near the valley points, where the\nshift-vector diverges. This is a prominent example that the band geometry can\nplay essential roles in the fundamental properties of solids."
    },
    {
        "anchor": "Antiferromagnetic dichroism and Davydov splitting of 3d-excitons in a\n  complex multisublattice magnetoelectric CuB2O4: The space and time symmetry breaking at magnetic phase transitions in\nmultiferroics results in a number of strongly pronounced optical effects. Our\nhigh-resolution spectroscopic study of 3d- excitons in a complex\nmulti-sublattice magnetoelectric CuB2O4 demonstrates that, among those, a large\nantiferromagnetic linear dichroism is observed which is highly\nsublattice-sensitive to subtle changes in the spin subsystems. We prove that\nthe discovered linear dichroism is related microscopically to the magnetic\nDavydov splitting of the exciton states. We announce a novel magnetic phase\ntransition and argue that an elliptical spiral structure rather than a simple\ncircular helix is realized in the incommensurate phase, these findings being\noverlooked in previous studies by optical and other techniques. We claim that\nthis spectroscopic method can be effectively applied to other materials for\nrevealing hidden features of magnetic structures and phase transitions.",
        "positive": "Ferromagnetism in layered metallic Fe1/4TaS2 in the presence of\n  conventional and Dirac carriers: In this paper we present the microscopic origin of the ferromagnetism of\nFe0.25TaS2 and its finite-temperature magnetic properties. We first obtain the\nband structures of Fe0.25TaS2 by the first-principles calculations and find\nthat both conventional and Dirac carriers coexist in metallic Fe0.25TaS2.\nAccordingly, considering the spin-orbit coupling of Fe 3d ion, we derive an\neffective RKKY-type Hamiltonian between Fe spins in the presence of both the\nconventional parabolic-dispersion and the Dirac linear-dispersion carriers,\nwhich contains a Heisenberg-like, an Ising-like and an XY-like term. In\naddition, we obtain the ferromagnetic Curie temperature Tc by using the cluster\nself-consistent field method. Our results could address not only the high\nferromagnetic Curie temperature, but also the large magnetic anisotropy in\nFexTaS2."
    },
    {
        "anchor": "Thermal transport evolution due to nanostructural transformations in\n  Ga-doped indium-tin-oxide thin films: We report on a comprehensive theoretical and experimental investigation of\nthermal conductivity in indium-tin-oxide (ITO) thin films with various Ga\nconcentrations (0-30 at. %) deposited by spray pyrolysis technique. X-Ray\ndiffraction (XRD) and scanning electron microscopy have shown a structural\ntransformation in the range 15-20 at. % Ga from the nanocrystalline to the\namorphous phase. Room temperature femtosecond time domain thermoreflectance\nmeasurements showed nonlinear decrease of thermal conductivity in the range\n2.0-0.5 W/(m K) depending on Ga doping level. Comparing density functional\ntheory calculations with XRD data it was found that Ga atoms substitute In\natoms in the ITO nanocrystals retaining Ia-3 space group symmetry. The\ncalculated phonon dispersion relations revealed that Ga doping leads to the\nappearance of hybridized metal atom vibrations with avoided-crossing behavior.\nThese hybridized vibrations possess shortened mean free paths and are the main\nreason behind the thermal conductivity drop in nanocrystalline phase. An\nevolution from propagative to diffusive phonon thermal transport in ITO:Ga with\n15-20 at. % of Ga was established. The suppressed thermal conductivity of\nITO:Ga thin films deposited by spray pyrolysis may be crucial for their\nthermoelectric applications.",
        "positive": "Unveiling the room temperature magnetoelectricity of troilite FeS: The amazing possibility of magnetoelectric crystals to cross couple electric\nand magnetic properties without the need of time-dependent Maxwell's equations\nhas attracted a lot of interest in material science. This enthusiasm has\nre-emerged during the last decade where magnetoelectric and multiferroic\ncrystals have captivated a tremendous number of studies, mostly driven by the\nquest of low-power-consumption spintronic devices. While several new candidates\nhave been discovered, the desirable magnetoelectric coupling at room\ntemperature is still sparse and calls for new promising candidates. Here, we\nshow from first-principles studies that the troilite phase of the iron sulfide\nbased compounds, one of the most common mineral of Earth, Moon, Mars or\nmeteors, is magnetoelectric up to temperatures as high as 415 K."
    },
    {
        "anchor": "New Polymorphs of Two-Dimensional Indium Selenide with Enhanced\n  Electronic Properties: The two-dimensional (2D) semiconductor indium selenide (InSe) has attracted\nsignificant interest due its unique electronic band structure, high electron\nmobility and wide tunability of its band gap energy achieved by varying the\nlayer thickness. All these features make 2D InSe a potential candidate for\nadvanced electronic and optoelectronic applications. Here, we report on the\ndiscovery of new polymorphs of InSe with enhanced electronic properties. Using\na global structure search that combines artificial swarm intelligence with\nfirst-principles energetic calculations, we identify polymorphs that consist of\na centrosymmetric monolayer belonging to the point group D$_{3d}$, distinct\nfrom the well-known polymorphs based on the D$_{3h}$ monolayers that lack\ninversion symmetry. The new polymorphs are thermodynamically and kinetically\nstable, and exhibit a wider optical spectral response and larger electron\nmobilities compared to the known polymorphs. We discuss opportunities to\nsynthesize these newly discovered polymorphs and viable routes to identify them\nby X-ray diffraction, Raman spectroscopy and second harmonic generation\nexperiments.",
        "positive": "Thickness dependence of the degree of spin polarization of the\n  electrical current in permalloy thin films: Spin-polarized electrical transport is investigated in $\nAl_{2}O_{3}/Ni_{80}Fe_{20}/Al_{2}O_{3}$ thin films for permalloy thickness\nbetween 6 and 20nm. The degree of spin-polarization of the current flowing in\nthe plane of the film is measured through the current induced spin wave Doppler\nshift. We find that it decreases as the film thickness decreases, from 0.72 at\n20nm to 0.46 at 6nm. This decrease is attributed to a spin depolarization\ninduced by the film surfaces. A model is proposed which takes into account the\ncontributions of the different sources of electron scattering (alloy disorder,\nphonons, thermal magnons, grain boundaries, film surfaces) to the measured\nspin-dependent resistivities."
    },
    {
        "anchor": "Close packed structure with finite range interaction: computational\n  mechanics of layer pair interaction: The stacking problem is approached by computational mechanics, using an Ising\nnext nearest neighbor model. Computational mechanics allows to treat the\nstacking arrangement as an information processing system in the light of a\nsymbol generating process. A general method for solving the stochastic matrix\nof the random Gibbs field is presented, and then applied to the problem at\nhand. The corresponding phase diagram is then discussed in terms of the\nunderlying $\\epsilon$-machine, or optimal finite state machine, describing\nstatistically the system. The occurrence of higher order polytypes at the\nborders of the phase diagram is also analyzed. Discussion of the applicability\nof the model to real system such as ZnS and Cobalt is done. The method derived\nis directly generalizable to any one dimensional model with finite range\ninteraction.",
        "positive": "Pressure, temperature, and orientation dependent thermal conductivity of\n  $\u03b1$-1,3,5-trinitro-1,3,5-triazinane ($\u03b1$-RDX): We use reverse non-equilibrium molecular dynamics (RNEMD) simulations to\ndetermine the thermal conductivity in $\\alpha$-RDX in the <100>, <010>, and\n<001> crystallographic directions. Simulations are carried out with the\nSmith-Bharadwaj non-reactive empirical interatomic potential [Smith &\nBharadwaj, J. Phys. Chem. B 103, 3570(1999)], which represents the\nthermo-elastic properties of RDX with good accuracy. As an illustration, we\nreport the temperature and pressure dependence of lattice constants of\n$\\alpha$-RDX, which compare well with experimental and ab initio results, as do\nlinear and volume thermal expansion coefficients, which we also calculate. We\nfind that the thermal conductivity depends linearly on the inverse temperature\nin the 200-400K regime due to the decrease in the phonon mean free path. The\nthermal conductivity also exhibits anisotropy, with a maximum difference at\n300K of 24% between the <001> and <010> directions, an effect that remains when\ntemperature increases. Thermal conductivity in the <100> direction is mostly\nbetween the two other directions, although crossovers are predicted with <001>\nat high temperature, and <010> at low temperature under pressure. We observe\nthat the thermal conductivity varies linearly with pressure up to 4 GPa. The\ndata are fitted to analytical functions for interpolation/extrapolation and use\nin continuum simulations. MD results are validated against experiments using\nimpulsive stimulated thermal scattering (ISTS) on RDX single crystals at 293K\nand ambient pressure, showing good qualitative and quantitative agreement: same\nordering between the three principal orientations, and an average error of 10%\nbetween the experiments and the model. These results provide confidence that\nthe extracted analytical functions using the RNEMD methodology and the\nSmith-Bharadwaj potential can be applied to model the thermal conductivity of\n$\\alpha$-RDX."
    },
    {
        "anchor": "Neutron scattering study of commensurate magnetic ordering in single\n  crystal CeSb$_2$: Temperature and field-dependent magnetization $M(H,T)$ measurements and\nneutron scattering study of a single crystal CeSb$_2$ are presented. Several\nanomalies in the magnetization curves have been confirmed at low magnetic\nfield, i.e., 15.6 K, 12 K, and 9.8 K. These three transitions are all\nmetamagnetic transitions (MMT), which shift to lower temperatures as the\nmagnetic field increases. The anomaly at 15.6 K has been suggested as\nparamagnetic (PM) to ferromagnetic (FM) phase transition. The anomaly located\nat around 12 K is antiferromagnetic-like transition, and this turning point\nwill clearly split into two when the magnetic field $H\\geq0.2$ T. Neutron\nscattering study reveals that the low temperature ground state of CeSb$_2$\norders antiferromagnetically with commensurate propagation wave vectors\n$\\textbf{k}=(-1,\\pm1/6,0)$ and $\\textbf{k}=(\\pm1/6,-1,0)$, with N\\'eel\ntemperature $T_N\\sim9.8$ K. This transition is of first-order, as shown in the\nhysteresis loop observed by the field cooled cooling (FCC) and field cooled\nwarming (FCW) processes.",
        "positive": "Silicon in the Quantum Limit: Quantum Computing and Decoherence in\n  Silicon Architectures: Semiconductor architectures hold promise for quantum information processing\n(QIP) applications due to their large industrial base and perceived scalability\npotential. Electron spins in silicon in particular may be an excellent\narchitecture for QIP and also for spin electronics (spintronics) applications.\nWhile the charge of an electron is easily manipulated by charged gates, the\nspin degree of freedom is well isolated from charge fluctuations. Inherently\nsmall spin-orbit coupling and the existence of a spin-zero Si isotope\nfacilitate long single spin qubit coherence times. Here we consider the\nrelaxation properties of localized electronic states in silicon due to donors,\nquantum wells, and quantum dots, including effects due to phonons and Rashba\nspin-orbit coupling. Our analysis is impeded by the complicated, many-valley\nband structure of silicon and previously unaddressed physics in silicon quantum\nwells. We find that electron spins in silicon and especially strained silicon\nhave excellent decoherence properties. Where possible we compare with\nexperiment to test our theories. We go beyond issues of coherence in a quantum\ncomputer to problems of control and measurement. Precisely what makes spin\nrelaxation so long in semiconductor architectures makes spin measurement so\ndifficult. To address this, we propose a new scheme for spin readout which has\nthe added benefit of automatic spin initialization, a vital component of\nquantum computing and quantum error correction. Our results represent important\npractical milestones on the way to the design and construction of a\nsilicon-based quantum computer."
    },
    {
        "anchor": "Surface oxides, carbides, and impurities on RF superconducting Nb and\n  Nb3Sn: A comprehensive analysis: Surface structures on radio-frequency (RF) superconductors are crucially\nimportant in determining their interaction with the RF field. Here we\ninvestigate the surface compositions, structural profiles, and valence\ndistributions of oxides, carbides, and impurities on niobium (Nb) and\nniobium-tin (Nb3Sn) in situ under different processing conditions. We establish\nthe underlying mechanisms of vacuum baking and nitrogen processing in Nb and\ndemonstrate that carbide formation induced during high-temperature baking,\nregardless of gas environment, determines subsequent oxide formation upon air\nexposure or low-temperature baking, leading to modifications of the electron\npopulation profile. Our findings support the combined contribution of surface\noxides and second-phase formation to the outcome of ultra-high vacuum baking\n(oxygen processing) and nitrogen processing. Also, we observe that\nvapor-diffused Nb3Sn contains thick metastable oxides, while electrochemically\nsynthesized Nb3Sn only has a thin oxide layer. Our findings reveal fundamental\nmechanisms of baking and processing Nb and Nb3Sn surface structures for\nhigh-performance superconducting RF and quantum applications",
        "positive": "Raman spectra of epitaxial graphene on SiC and of epitaxial graphene\n  transferred to SiO2: Raman spectra were measured for mono-, bi- and trilayer graphene grown on SiC\nby solid state graphitization, whereby the number of layers was pre-assigned by\nangle-resolved ultraviolet photoemission spectroscopy. It was found that the\nonly unambiguous fingerprint in Raman spectroscopy to identify the number of\nlayers for graphene on SiC(0001) is the linewidth of the 2D (or D*) peak. The\nRaman spectra of epitaxial graphene show significant differences as compared to\nmicromechanically cleaved graphene obtained from highly oriented pyrolytic\ngraphite crystals. The G peak is found to be blue-shifted. The 2D peak does not\nexhibit any obvious shoulder structures but it is much broader and almost\nresembles a single-peak even for multilayers. Flakes of epitaxial graphene were\ntransferred from SiC onto SiO2 for further Raman studies. A comparison of the\nRaman data obtained for graphene on SiC with data for epitaxial graphene\ntransferred to SiO2 reveals that the G peak blue-shift is clearly due to the\nSiC substrate. The broadened 2D peak however stems from the graphene structure\nitself and not from the substrate."
    },
    {
        "anchor": "Fracture of bio-cemented sands: Bio-chemical reactions enable the production of biomimetic materials such as\nsandstones. In the present study, microbiologically-induced calcium carbonate\nprecipitation (MICP) is used to manufacture laboratory-scale specimens for\nfracture toughness measurement. The mode I and mixed-mode fracture toughnesses\nare measured as a function of cementation, and are correlated with strength,\npermeability and porosity. A micromechanical model is developed to predict the\ndependence of mode I fracture toughness upon the degree of cementation. In\naddition, the role of the crack tip $T$-stress in dictating kink angle and\ntoughness is determined for mixed mode loading. At a sufficiently low degree of\ncementation, the zone of microcracking in the vicinity of the crack tip is\nsufficiently large for a crack tip $K$-field to cease to exist and for crack\nkinking theory to not apply. The interplay between cementation and fracture\nproperties of sedimentary rocks is explained; this understanding underpins a\nwide range of rock fracture phenomena including hydraulic fracture.",
        "positive": "Low temperature tunneling current enhancement in silicide/Si Schottky\n  contacts with nanoscale barrier width: The low temperature electrical behavior of adjacent silicide/Si Schottky\ncontacts with or without dopant segregation is investigated. The electrical\ncharacteristics are very well modeled by thermionic-field emission for\nnon-segregated contacts separated by micrometer-sized gaps. Still, an excess of\ncurrent occurs at low temperature for short contact separations or\ndopant-segregated contacts when the voltage applied to the device is\nsufficiently high. From two-dimensional self-consistent non-equilibrium Green's\nfunction simulations, the dependence of the Schottky barrier profile on the\napplied voltage, unaccounted for in usual thermionic-field emission models, is\nfound to be the source of this deviation."
    },
    {
        "anchor": "A small shoulder of optical absorption in polycrystalline HfO2 by LDA+U\n  approach: The dielectric function of the wide-gap optical material HfO2 is investigated\nby the local density approximation (LDA) +U approach. We focus on the origin of\nthe shoulder-like structure near the edge of the band gap in the imaginary part\nof the dielectric function, which has been observed on the thin films of\nmonoclinic HfO2. A comparison study on the three polymorphs of hafnia shows\nthat regardless of the underlying crystal structure, the existence of the\nshoulder is directly controlled by the value of the shortest length of Hf-O\nbonds. The proposition is further supported by the numerical simulations of\nisostatic pressing. A possible implication in high-pressure measurements is\nsuggested accordingly.",
        "positive": "Nonlinear acoustic characterization of heterogeneous plasticity in bent\n  aluminium samples: Knowledge of the state of plastic deformation in metallic structures is vital\nto prevent failure. This is why non-destructive acoustic tests based on the\nmeasurement of first order elastic constants have been developed and\nintensively used. However, plastic deformations, which are usually\nheterogeneous in space, may be invisible to these methods if the variation of\nthe elastic constants is too small. In recent years, digital image correlation\ntechniques, based on measurements carried out at the surface of a sample, have\nbeen successfully used in conjunction with finite element modeling to gain\ninformation about plastic deformation in the sample interior. Acoustic waves\ncan penetrate deep into a sample and offer the possibility of probing into the\nbulk of a plastically deformed material. Previously, we have demonstrated that\nnonlinear acoustic methods are far more sensitive to changes in dislocation\ndensity than linear ones. Here, we show that the nonlinear Second Harmonic\nGeneration method (SHG) is sensitive enough to detect different zones of von\nMises stress as well as effective plastic strain in centimeter-size aluminium\npieces. This is achieved by way of ultrasonic measurements on a sample that has\nundergone a three-point bending test. Because of the relatively low stress and\nsmall deformations, the sample undergoes plastic deformation by dislocation\nproliferation. Thus, we conclude that the nonlinear parameter measured by SHG\nis also sensitive to dislocation density. Our experimental results agree with\nnumerical results obtained by Finite Element Method (FEM) modeling. We also\nsupport the acoustic results by X-Ray Diffraction measurements (XRD). Although\nintrusive and less accurate, they also agree with the acoustic measurements and\nplastic deformations in finite element simulations."
    },
    {
        "anchor": "Dynamical Projective Operatorial Approach (DPOA) for out-of-equilibrium\n  systems and its application to TR-ARPES: Efficiently simulating real materials under the application of a\ntime-dependent field and computing reliably the evolution over time of relevant\nresponse functions, such as the TR-ARPES signal or differential transient\noptical properties, has become one of the main concerns of modern condensed\nmatter theory in response to the recent developments in all areas of\nexperimental out-of-equilibrium physics. In this manuscript, we propose a novel\nmodel-Hamiltonian method, the dynamical projective operatorial approach (DPOA),\ndesigned and developed to overcome some of the limitations and drawbacks of\ncurrently available methods. Relying on (i) many-body second-quantization\nformalism and composite operators, DPOA is in principle capable of handling\nboth weakly and strongly correlated systems, (ii) tight-binding approach and\nwannierization of DFT band structures, DPOA naturally deals with the complexity\nand the very many degrees of freedom of real materials, (iii) dipole gauge and\nPeierls substitution, DPOA is built to address pumped systems and, in\nparticular, pump-probe spectroscopies, (iv) a Peierls expansion we have devised\nad hoc, DPOA is numerically extremely efficient and fast. The latter expansion\nclarifies how single- and multi-photon resonances, rigid shifts, band\ndressings, and different types of sidebands emerge and allows understanding the\nrelated phenomenologies. Comparing DPOA to the single-particle density-matrix\napproach and the Houston method (this latter is generalized to\nsecond-quantization formalism), we show how it can compute multi-particle\nmulti-time correlation functions and go well beyond these approaches for real\nmaterials. We also propose protocols for evaluating the strength of single- and\nmulti-photon resonances and for assigning the residual excited electronic\npopulation at each crystal momentum and band to a specific excitation process.\nThe expression for ...",
        "positive": "Electronic Phase Separation in Manganite/Insulator Interfaces: By using a realist microscopic model, we study the electric and magnetic\nproperties of the interface between a half metallic manganite and an insulator.\nWe find that the lack of carriers at the interface debilitates the double\nexchange mechanism, weakening the ferromagnetic coupling between the Mn ions.\nIn this situation the ferromagnetic order of the Mn spins near the interface is\nunstable against antiferromagnetic CE correlations, and a separation between\nferromagnetic/metallic and antiferromagnetic/insulator phases at the interfaces\ncan occur. We obtain that the insertion of extra layers of undoped manganite at\nthe interface introduces extra carriers which reinforce the double exchange\nmechanism and suppress antiferromagnetic instabilities."
    },
    {
        "anchor": "Ab initio calculation of the magnetic Gibbs free energy of materials\n  using magnetically constrained supercells: We present a first-principles approach for the computation of the magnetic\nGibbs free energy of materials using magnetically constrained supercell\ncalculations. Our approach is based on an adiabatic approximation of slowly\nvarying local moment orientations, the so-called finite-temperature disordered\nlocal moment picture. It describes magnetic phase transitions and how\nelectronic and/or magnetostructural mechanisms generate a discontinuous\n(first-order) character. We demonstrate that the statistical mechanics of the\nlocal moment orientations can be described by an affordable number of supercell\ncalculations containing noncollinear magnetic configurations. The applicability\nof our approach is illustrated by firstly studying the ferromagnetic state in\nbcc Fe. We then investigate the temperature-dependent properties of a\ntriangular antiferromagnetic state stabilizing in two antiperovskite systems\nMn$_3$AN (A = Ga, Ni). Our calculations provide the negative volume expansion\nof these materials as well as the ab initio origin of the discontinuous\ncharacter of the phase transitions, electronic and/or magnetostructural, in\ngood agreement with experiment.",
        "positive": "A new generation of effective core potentials from correlated and\n  spin-orbit calculations: selected heavy elements: We introduce new correlation consistent effective core potentials (ccECPs)\nfor the elements I, Te, Bi, Ag, Au, Pd, Ir, Mo, and W with $4d$, $5d$, $6s$ and\n$6p$ valence spaces. These ccECPs are given as a sum of spin-orbit averaged\nrelativistic effective potential (AREP) and effective spin-orbit (SO) terms.\nThe construction involves several steps with increasing refinements from more\nsimple to fully correlated methods. The optimizations are carried out with\nobjective functions that include weighted many-body atomic spectra,\nnorm-conservation criteria, and spin-orbit splittings. Transferability tests\ninvolve molecular binding curves of corresponding hydride and oxide dimers. The\nconstructed ccECPs are systematically better and in a few cases on par with\nprevious effective core potential (ECP) tables on all tested criteria and\nprovide a significant increase in accuracy for valence-only calculations with\nthese elements. Our study confirms the importance of the AREP part in\ndetermining the overall quality of the ECP even in the presence of sizable\nspin-orbit effects. The subsequent quantum Monte Carlo (QMC) calculations point\nout the importance of accurate trial wave functions which in some cases (mid\nseries transition elements) require treatment well beyond single-reference."
    },
    {
        "anchor": "Crystal Structure Manipulation of the Exchange Bias in an\n  Antiferromagnetic Film: Exchange bias is one of the most extensively studied phenomena in magnetism,\nsince it exerts a unidirectional anisotropy to a ferromagnet (FM) when coupled\nto an antiferromagnet (AFM) and the control of the exchange bias is therefore\nvery important for technological applications, such as magnetic random access\nmemory and giant magnetoresistance sensors. In this letter, we report the\ncrystal structure manipulation of the exchange bias in epitaxial hcp Cr2O3\nfilms. By epitaxially growing twined (10-10) oriented Cr2O3 thin films, of\nwhich the c axis and spins of the Cr atoms lie in the film plane, we\ndemonstrate that the exchange bias between Cr2O3 and an adjacent permalloy\nlayer is tuned to in-plane from out-of-plane that has been observed in (0001)\noriented Cr2O3 films. This is owing to the collinear exchange coupling between\nthe spins of the Cr atoms and the adjacent FM layer. Such a highly anisotropic\nexchange bias phenomenon is not possible in polycrystalline films.",
        "positive": "Microstructure-dependent local strain behavior in polycrystals through\n  in situ scanning electron microscope tensile experiments: Digital image correlation of laser-ablated platinum nanoparticles on the\nsurface of a polycrystalline metal (nickel-based superalloy Rene 88DT) was used\nto obtain the local strain behavior from an in situ scanning electron\nmicroscope tensile experiment at room temperature. By fusing this information\nwith crystallographic orientations from EBSD, a subsequent analysis shows that\nthe average maximum shear strain tends to increase with increasing Schmid\nfactor. Additionally, the range of the extreme values for the maximum shear\nstrain also increases closer to the grain boundary, signifying that grain\nboundaries and triple junctions accumulate plasticity at strains just beyond\nyield in polycrystalline Rene 88DT. In situ experiments illuminating\nmicrostructure-property relationships of this ilk may be important for\nunderstanding damage nucleation in polycrystalline metals at high temperatures."
    },
    {
        "anchor": "Theoretical prediction and experimental study of a ferromagnetic shape\n  memory alloy: Ga_2MnNi: We predict the existence of a new ferromagnetic shape memory alloy Ga_2MnNi\nusing density functional theory. The martensitic start temperature (T_M) is\nfound to be approximately proportional to the stabilization energy of the\nmartensitic phase (deltaE_tot) for different shape memory alloys. Experimental\nstudies performed to verify the theoretical results show that Ga_2MnNi is\nferromagnetic at room temperature and the T_M and T_C are 780K and 330K,\nrespectively. Both from theory and experiment, the martensitic transition is\nfound to be volume conserving that is indicative of shape memory behavior.",
        "positive": "Band structure derived properties of HfO2 from first principles\n  calculations: The electronic band structures and optical properties of cubic, tetragonal,\nand monoclinic phases of HfO2 are calculated using the first-principles linear\naugmented plane-wave method, within the density functional theory and\ngeneralized gradient approximation, and taking into account full-relativistic\ncontributions. From the band structures, the electron- and hole-effective\nmasses were obtained. Relativistic effects play an important role, which is\nreflected in the effective masses values and in the detailed structure of the\ndielectric function. The calculated imaginary part of the dielectric function\nand refractive index are in good agreement with the data reported in the\nliterature."
    },
    {
        "anchor": "Thermoballistic spin-polarized electron transport in paramagnetic\n  semiconductors: Spin-polarized electron transport in diluted magnetic semiconductors (DMS) in\nthe paramagnetic phase is described within the thermoballistic transport model.\nIn this (semiclassical) model, the ballistic and diffusive transport mechanisms\nare unified in terms of a thermoballistic current in which electrons move\nballistically across intervals enclosed between arbitrarily distributed points\nof local thermal equilibrium. The contribution of each interval to the current\nis governed by the momentum relaxation length. Spin relaxation is assumed to\ntake place during the ballistic electron motion. In paramagnetic DMS exposed to\nan external magnetic field, the conduction band is spin-split due to the giant\nZeeman effect. In order to deal with this situation, we extend our previous\nformulation of thermoballistic spin-polarized transport so as to take into\naccount an arbitrary (position-dependent) spin splitting of the conduction\nband. The current and density spin polarizations as well as the\nmagnetoresistance are each obtained as the sum of an equilibrium term\ndetermined by the spin-relaxed chemical potential, and an off-equilibrium\ncontribution expressed in terms of a spin transport function that is related to\nthe splitting of the spin-resolved chemical potentials. The procedures for the\ncalculation of the spin-relaxed chemical potential and of the spin transport\nfunction are outlined. As an illustrative example, we apply the thermoballistic\ndescription to spin-polarized transport in DMS/NMS/DMS heterostructures formed\nof a nonmagnetic semiconducting sample (NMS) sandwiched between two DMS layers.\nWe evaluate the current spin polarization and the magnetoresistance for this\ncase and, in the limit of small momentum relaxation length, find our results to\nagree with those of the standard drift-diffusion approch to electron transport.",
        "positive": "Wannier interpolation of one-particle Green's functions from\n  coupled-cluster singles and doubles (CCSD): We propose two schemes for interpolation of the one-particle Green's function\n(GF) calculated within coupled-cluster singles and doubles (CCSD) method for a\nperiodic system. They use Wannier orbitals for circumventing huge cost for a\nlarge number of sampled k points. One of the schemes is the direct\ninterpolation, which obtains the GF straightforwardly by using Fourier\ntransformation. The other is the self-energy-mediated interpolation, which\nobtains the GF via the Dyson equation. We apply the schemes to a LiH chain and\ntrans-polyacetylene and examine their validity in detail. It is demonstrated\nthat the direct-interpolated GFs suffer from numerical artifacts stemming from\nslow convergence of CCSD GFs in real space, while the self-energy-mediated\ninterpolation provides more physically appropriate GFs due to the localized\nnature of CCSD self-energies. Our schemes are also applicable to other\nexplicitly correlated methods capable of providing GFs."
    },
    {
        "anchor": "Noninvasive Photodelamination of van der Waals Semiconductors for\n  High-Performance Electronics: Atomically thin two-dimensional (2D) van der Waals semiconductors are\npromising candidate materials for post-silicon electronics. However, it remains\nchallenging to attain completely uniform monolayer semiconductor wafers free of\nover-grown islands. Here, we report the observation of the energy funneling\neffect and ambient photodelamination phenomenon in inhomogeneous few-layer\nWS$_2$ flakes under low illumination fluencies down to several nW/$\\mu$m$^{2}$\nand its potential as a non-invasive post-etching strategy for selectively\nstripping the local excessive overlying islands. Photoluminescent tracking on\nthe photoetching traces reveals relatively fast etching rates around\n$0.3-0.8\\,\\mu$m/min at varied temperatures and an activation energy of\n$1.7\\,$eV. By using crystallographic and electronic characterization, we also\nconfirm the non-invasive nature of the low-power photodelamination and the\nhighly preserved lattice quality in the as-etched monolayer products, featuring\na comparable average density of atomic defects (ca.$4.2\\times\n10^{13}\\,$cm$^{-2}$) to pristine flakes and a high electron mobility up to\n$80\\,$cm$^{2}\\cdot$V$^{-1}\\cdot$s$^{-1}$) at room temperature. This approach\nopens a non-invasive photoetching route for thickness uniformity management in\n2D van der Waals semiconductor wafers for electronic applications.",
        "positive": "Palladium: A localised paramagnetism: We report on the origin of ferromagnetic like behaviour observed for 2.4 nm\nsize Pd nanoparticles. Localised magnetic moments on metallic surfaces have\nbeen recently shown to induce orbital motion of the itinerant electrons via\nspin-orbit coupling. As a result of this coupling the magnetic anisotropy is\nenhanced and the surface magnetic moments can be blocked up to above room\ntemperature. Since Pd has been customary treated as a paradigmatic itinerant\nsystem, localisation of magnetic moments at its surfaces was not initially\nexpected. However, it is shown, through the experimental thermal dependence of\nboth magnetic susceptibility and Hall resistance, that magnetism of bulk Pd, is\na localised paramagnetism and, consequently, can give rise to permanent\nmagnetism at its surface. Such surface permanent magnetism is experimentally\nobserved only when the percentage of surface moments is outstanding as is the\ncase for nanoparticles."
    },
    {
        "anchor": "First-Principles Study of Secondary Slip in Zirconium: Although the favored glide planes in hexagonal close-packed Zr are prismatic,\nscrew dislocations can escape their habit plane to glide in either pyramidal or\nbasal planes. Using abinitio calculations within the nudged elastic band\nmethod, we show that, surprisingly, both events share the same thermally\nactivated process with an unusual conservative motion of the prismatic stacking\nfault perpendicularly to itself. Halfway through the migration, the screw\ndislocation adopts a nonplanar metastable configuration with stacking faults in\nadjacent prismatic planes joined by a two-layer pyramidal twin.",
        "positive": "Stability and electronic properties of planar defects in quaternary\n  I2-II-IV-VI4 semiconductors: Extended defects such as stacking faults and anti-site domain boundaries can\nperturb the band edges in Cu$_2$ZnSnS$_4$ and Cu$_2$ZnSnSe$_4$, acting as a\nweak electron barrier or a source for electron capture, respectively. In order\nto find ways to prohibit the formation of planar defects, we investigated the\neffect of chemical substitution on the stability of the intrinsic stacking\nfault and metastable polytypes and analyze their electrical properties.\nSubstitution of Ag for Cu makes stacking faults less stable, whereas the other\nsubstitutions (Cd and Ge) promote their formation. Ge substitution has no\neffect on the electron barrier of the intrinsic stacking fault, but Cd\nsubstitution reduces the barrier energy and Ag substitution makes the stacking\nfault electron capture. While Cd substitution stabilizes the stannite\nstructure, chemical substitutions make the primitive-mixed CuAu (PMCA)\nstructure less stable with respect to the ground-state kesterite structure."
    },
    {
        "anchor": "Hydrothermal Synthesis of Carbon and Sulfur Mono-Doped Sodium Tantalates: A set of experiments was conducted to synthesize doped and undoped sodium\ntantalates with carbon and sulfur in energy efficient single-step hydrothermal\nprocess. Undoped sodium tantalate nanocubes were synthesized at 140$^\\circ$C\nand doped one at 180$^\\circ$C for 12 hours in rich alkaline atmosphere. The\nsizes of undoped, carbon-doped, and sulfur-doped sodium tantalate nanocubes\nwere 38 nm, 45 nm, and 40 nm, respectively. The morphological, elemental,\ncompositional, structural, thermal, and photophysical properties of\nas-synthesized doped and undoped sodium tantalate (NaTaO$_3$) were\ncharacterized using scanning electron microscope (SEM), energy dispersive x-ray\nspectroscope (EDS), Raman spectroscopy, X-ray powder diffraction (XRD), thermal\ngravimetric analysis (TGA), Fourier transform infrared spectrophotometer\n(FTIR), and UV-vis spectrophotometer. The sulfur doped NaTaO$_3$ shows a higher\nphotocatalytic activity in degradation of methylene blue than carbon doped and\nthe undoped NaTaO$_3$. The band gaps of undoped NaTaO$_3$, carbon doped\nc-NaTaO$_3$, and sulfur doped s-NaTaO$_3$ were calculated to be 3.94 eV, 3.8\neV, and 3.52 eV, respectively using Tauc plot.",
        "positive": "Handbook on Best Practice for Minimising Beam Induced Damage during IBA: This handook is intended as a resource for scientists who use Ion Beam\nAnalysis (IBA), to help them understand and minimise beam damage induced during\nthe analysis. The basic physics of ion-matter interactions, from the perspectve\nof damage induced by the beam during Ion Beam Analysis, is presented at a level\nsuitable for post-graduate students. The specificities of damage induced in\nwidely used IBA techniques such as Backscattering Spectrometry (RBS), Nuclear\nReaction Analysis (NRA), Elastic Recoil Detection Analysis (ERDA) and\nParticle-Induced X-ray Emission (PIXE) are presented, followed by sections on\ndamage induced during analysis of different classes of materials such as\nmetals, semiconductors or polymers. A comprehensive bibliography is included."
    },
    {
        "anchor": "Recent progress in exploring magnetocaloric materials: Magnetic refrigeration based on the magnetocaloric effect (MCE) of materials\nis a potential technique that has prominet advantages over the currently used\ngas compression-expansion technique in the sense of its high efficiency and\nenvironment friendship. In this article, our recent progress in explorating\neffective MCE materials is reviewed with the emphasis on the MCE in the\nLaFe13-xSix-based alloys with a first order magnetic transition discovered by\nus. These alloys show large entropy changes in a wide temperature range near\nroom temperature. Effects of magnetic rare-earth doping, interstitial atom, and\nhigh pressure on the MCE have been systematically studied. Special issues such\nas appropriate approaches to determining the MCE associated with the\nfirst-order magnetic transition, the depression of magnetic and thermal\nhystereses, and the key factors determining the magnetic exchange in alloys of\nthis kind are discussed. The applicability of the giant MCE materials to the\nmagnetic refrigeration near ambient temperature is evaluated. A brief review of\nother materials with significant MCE is also presented in the article.",
        "positive": "On the \"Causality Paradox\" of Time-Dependent Density Functional Theory: I show that the so-called causality paradox of time-dependent density\nfunctional theory arises from an incorrect formulation of the variational\nprinciple for the time evolution of the density. The correct formulation not\nonly resolves the paradox in real time, but also leads to a new expression for\nthe causal exchange-correlation kernel in terms of Berry curvature.\nFurthermore, I show that all the results that were previously derived from\nsymmetries of the action functional remain valid in the present formulation.\nFinally, I develop a model functional theory which explicitly demonstrates the\nworkings of the new formulation."
    },
    {
        "anchor": "Stacking-Mediated Diffusion of Ruthenium Nanoclusters in Graphite: The diffusion, penetration and intercalation of metallic atomic dopants is an\nimportant question for various graphite applications in engineering and\nnanotechnology. We have performed systematic first-principles calculations of\nthe behaviour of ruthenium nanoclusters on a graphene monolayer and\nintercalated into a bilayer. Our computational results show that at a\nsufficiently high density of single Ru atom interstitials, intercalated atoms\ncan shear the surrounding lattice to an AA stacking configuration, an effect\nwhich weakens with increasing cluster size. Moreover, the interlayer stacking\nconfiguration, in turn, has a significant effect on cluster diffusion. We\ntherefore find different trends in diffusivity as a function of cluster size\nand interlayer stacking. For monolayer graphene and an AA graphene bilayer, the\nformation of small clusters generally lowers diffusion barriers, while the\nopposite behaviour is found for the preferred AB stacking configuration. These\nresults demonstrate that conditions of local impurity concentration and\ninterlayer disregistry are able to regulate the diffusivity of metallic\nimpurities in graphite.",
        "positive": "A Temperature Analysis of High-power AlGaN/GaN HEMTs: Galliumnitride has become a strategic superior material for space, defense\nand civil applications, primarily for power amplification at RF and mm-wave\nfrequencies. For AlGaN/GaN high electron mobility transistors (HEMT), an\noutstanding performance combined together with low cost and high flexibility\ncan be obtained using a System-in-a-Package (SIP) approach. Since thermal\nmanagement is extremely important for these high power applications, a hybrid\nintegration of the HEMT onto an AlN carrier substrate is proposed. In this\nstudy we investigate the temperature performance for AlGaN/GaN HEMTs integrated\nonto AlN using flip-chip mounting. Therefore, we use thermal simulations in\ncombination with experimental results using micro-Raman spectroscopy and\nelectrical dc-analysis."
    },
    {
        "anchor": "Thermal and nonthermal melting of silicon under femtosecond x-ray\n  irradiation: As it is known from visible light experiments, silicon under femtosecond\npulse irradiation can undergo the so-called 'nonthermal melting' if the density\nof electrons excited from the valence to the conduction band overcomes a\ncertain critical value. Such ultrafast transition is induced by strong changes\nin the atomic potential energy surface, which trigger atomic relocation.\nHowever, heating of a material due to the electron-phonon coupling can also\nlead to a phase transition, called 'thermal melting'. This thermal melting can\noccur even if the excited-electron density is much too low to induce\nnon-thermal effects. To study phase transitions, and in particular, the\ninterplay of the thermal and nonthermal effects in silicon under a femtosecond\nx-ray irradiation, we propose their unified treatment by going beyond the\nBorn-Oppenheimer approximation within our hybrid model based on tight binding\nmolecular dynamics. With our extended model we identify damage thresholds for\nvarious phase transitions in irradiated silicon. We show that electron-phonon\ncoupling triggers the phase transition of solid silicon into a low-density\nliquid phase if the energy deposited into the sample is above $\\sim0.65$ eV per\natom. For the deposited doses of over $\\sim0.9$ eV per atom, solid silicon\nundergoes a phase transition into high-density liquid phase triggered by an\ninterplay between electron-phonon heating and nonthermal effects. These\nthresholds are much lower than those predicted with the Born-Oppenheimer\napproximation ($\\sim2.1$ eV/atom), and indicate a significant contribution of\nelectron-phonon coupling to the relaxation of the laser-excited silicon. We\nexpect that these results will stimulate dedicated experimental studies,\nunveiling in detail various paths of structural relaxation within\nlaser-irradiated silicon.",
        "positive": "Investigation of the effect of Au2O3 dopant on elastic properties of\n  PbO-B2O3-SeO2: Er2O3 glass ceramics by ultrasonic techniques: Various elastic coefficients of Au2O3 doped PbO-B2O3-SeO2:Er2O3 (PBSE) glass\nceramics were evaluated as functions of Au2O3 content using ultrasonic velocity\nmeasurements. The elastic coefficients and micro-hardness showed a decreasing\ntendency with the concentration of Au2O3. Such decrease is attributed to the\nincreasing concentration of gold metallic particles and [SeO3]2- groups that\nacted as modifiers and induced imperfections in these samples. Obtained results\nwere observed to be consistent with the conclusions drawn from spectroscopic\nstudies that include X-ray photoelectron spectroscopy (XPS), infrared (IR),\nphotoluminescence (PL) and positron annihilation (PAL) spectroscopy studies.\nOverall, these studies have revealed that even though, the presence of gold\nmetallic particles is preferable for achieving superior luminescence and\nelectrical properties, presence of such particles caused to decrease the\nelastic coefficients and micro-hardness of these glass ceramics. However, when\nthe concentration of Au2O3 is increased beyond 0.075 mol%, we have observed a\nslight increase of elastic coefficients and micro-hardness."
    },
    {
        "anchor": "A Brief Review and Perspective on the Functional Biodegradable Films for\n  Food Packaging: High-performance, environmentally-friendly biodegradable packaging as\nsubstitutes for conventional plastics becomes severe demand to nowadays economy\nand society. As an aliphatic aromatic copolyester PBAT is recognized as the\npreferred alternative to traditional plastics. However, the relatively high\ncost and weak properties obstacles the widespread adoption of PBAT.\nModification pertaining to improve the properties, lower the cost, and include\nthe functional additives of PBAT is a continuous effort to meet the needs of\nfood accessibility, antibacterial properties, oxygen resistance, high\nmechanical strength, stable size, low moisture absorption, and various gas\npermeability for commercial competitiveness.",
        "positive": "Effect of lattice excitations on transient near edge X-ray absorption\n  spectroscopy: Time-dependent and constituent-specific spectral changes in soft near edge\nX-ray spectroscopy (XAS) of an [Fe/MgO]$_8$ metal/insulator heterostructure\nupon laser excitation are analyzed at the O K-edge with picosecond time\nresolution. The oxygen absorption edge of the insulator features a uniform\nintensity decrease of the fine structure at elevated phononic temperatures,\nwhich can be quantified by a simple simulation and fitting procedure presented\nhere. Combining X-ray absorption spectroscopy with ultrafast electron\ndiffraction measurements and ab initio calculations demonstrate that the\ntransient intensity changes in XAS can be assigned to a transient lattice\ntemperature. Thus, the sensitivity of transient near edge XAS to phonons is\ndemonstrated."
    },
    {
        "anchor": "Localization and hybridization of electronic states in thin films of Ag\n  on V(100): We have studied the electronic states in 1-5 layers thick Ag films on V(100),\nby means of ab initio density functional calculations. Due to the mismatch of\nthe electronic structure of Ag and V, quantum well states of both sp and d\ncharacter localized on Ag films are formed. We find that the hybridization of\nthe Ag quantum well states with the V orbitals is nevertheless important, and\nmust be taken into account in order to fully understand the observed\nproperties, in particular the energies and the dispersion of the photoemission\npeaks in ARPES experiments.",
        "positive": "Imaging the magnetic states in an actinide ferromagnet UMn$_2$Ge$_2$: We present studies of the magnetic domain structure of UMn$_2$Ge$_2$ single\ncrystals using a home-built low temperature magnetic force microscope. The\nmaterial has two distinct magnetic ordering temperatures, originating from the\nMn and U moments. At room temperature, where the Mn moments dominate, there are\nflower-like domain patterns similar to those observed in uniaxial ferromagnets.\nAfter exposing the sample to a one-tesla magnetic field near 40 K, the\nevolution of the magnetic domains are imaged through zero-field warming up to\n200 K. Near the ordering temperature of the uranium moments a clear change in\nthe domain wall motion is observed. The domain size analysis of the flower-like\npattern reveals that the domain structure is consistent with a model of\nbranching domains."
    },
    {
        "anchor": "Impact of particle size on the magnetic properties of highly crystalline\n  Yb3+ substituted Ni-Zn nanoferrites: Yb-substituted Ni-Zn ferrites have been synthesized using sol-gel auto\ncombustion method. The structural characterization of the compositions has been\nperformed by X-ray diffraction analysis, field emission scanning electron\nmicroscopy (FESEM), quantum design physical properties measurement system\n(PPMS). That ensured the formation of single phase cubic spinel structure.\nCrystallite and average grain size are calculated and found to decrease with\nincreasing Yb3+ contents. Saturation magnetization and Bohr magnetic moment\ndecrease while the coercivity increases with the increase in Yb3+ contents\nsuccessfully explained by the Neels collinear two sub-lattice model and\ncritical size effect, respectively. Critical particle size has been estimated\nat 6.4 nm, the transition point between single domain regime (below the\ncritical size) and multi-domain regime (beyond the critical size). Curie\ntemperature reduces due to the weakening of A-O-B super exchange interaction\nand redistribution of cations, confirmed by the M-T graph. The compositions\nretain ferromagnetic ordered structured below Curie temperature and above Curie\ntemperature, it becomes paramagnetic, making them plausible candidates for high\ntemperature magnetic device applications. The relative quality factor peak is\nobtained at a very high frequency, indicating the compositions could also be\napplicable for high frequency magnetic device applications.",
        "positive": "Giant magnetostriction in La2CoMnO6 synthesized by microwave irradiation: Polycrystalline insulating ferromagnetic double perovskite La2CoMnO6\npossessing monoclinic structure and a high ferromagnetic Curie temperature (TC\n= 222 K) was rapidly synthesized ( 30 min) by irradiating stoichiometric\nmixture of oxides with the microwave. The sample exhibits negative\nmagnetostriction, i.e., contraction of length along the magnetic field\ndirection in the ferromagnetic state. At 10 K, the parallel magnetostriction\ndoes not show saturation up to a magnetic field of 50 kOe where it reaches 610\nppm which is one of the highest values of magnetostriction found so far among\nperovskite oxides with 3d ions. The magnitude of magnetostriction decreases\nmonotonically as the temperature increases and becomes negligible above TC. The\ngiant magnetostriction in this double perovskite is suggested to originate from\nlarge spin-orbit coupling associated with Co2+ (d7) cation. The obtained\nmagnetostriction value is comparable to 630 ppm in an identical composition\nobtained through solid-state reaction over several days in a conventional\nfurnace which indicates the advantages of microwave-assisted synthesis in\nsaving reaction time and electric power without deteriorating physical\nproperties."
    },
    {
        "anchor": "Resonance Interaction Induced by Metal Surfaces Catalyses Atom Pair\n  Breakage: We present the theory for retarded resonance interaction between two\nidentical atoms at arbitrary positions near a metal surface. The dipole-dipole\nresonance interaction force that binds isotropically excited atom pairs\ntogether in free space may turn repulsive close to an ideal (totally\nreflecting) metal surface. On the other hand, close to an infinitely permeable\nsurface it may turn more attractive. We illustrate numerically how the\ndipole-dipole resonance interaction between two oxygen atoms near a metal\nsurface may provide a repulsive energy of the same order of magnitude as the\nground-state binding energy of an oxygen molecule. As a complement we also\npresent results from density-functional theory.",
        "positive": "New spin injection scheme based on spin gapless semiconductors: A\n  first-principles study: Spin injection efficiency based on conventional and/or half-metallic\nferromagnet/semiconductor is greatly limited by the Schmidt obstacle due to\nconductivity mismatch, here we proposed that by replacing the metallic\ninjectors with spin gapless semiconductors can significantly reduce the\nconductive mismatch to enhance spin injection efficiency. By performing first\nprinciples calculations based on superlattice structure, we have studied the\nrepresentative system of Mn2CoAl/semiconductor spin injector scheme. The\nresults showed that a high spin polarization was maintained at the interface in\nsystems of Mn2CoAl/Fe2VAl constructed with (100) interface and Mn2CoAl/GaAs\nwith (110) interface, and the latter is expected to possess long spin diffusion\nlength. Inherited from the spin gapless feature of Mn2CoAl, a pronounced dip\nwas observed around the Fermi level in the majority-spin density-of-states in\nboth systems, suggesting fast transport of the low-density carriers."
    },
    {
        "anchor": "Chemical instability of free-standing boron monolayers and properties of\n  oxidized borophene sheets: In this work we report results of step-by-step modeling of the oxidation of\nfree-standing boron monolayers of different types. Results of the calculations\ndemonstrate that the process of the oxidation is always exothermic and lead\ntoward the formation of foam-like boron oxide films with incorporated\nnon-oxidized small boron clusters. Some of these boron-oxide films demonstrate\nthe presence of chemically stable magnetic centers. Evaluation of the physical\nproperties of oxidized boprophene sheets (OBS) demonstrate it possible\napplication in solar energy, as sensors and coating against leakage of\nhydrogen.",
        "positive": "Finite strain constitutive modeling for shape memory alloys considering\n  transformation-induced plasticity and two-way shape memory effect: This work presents a three-dimensional constitutive model for shape memory\nalloys considering the TRansformation-Induced Plasticity (TRIP) as well as the\nTwo-Way Shape Memory Effect (TWSME) through a large deformation framework. The\npresented logarithmic strain based model is able to capture the large strains\nand rotations exhibited by SMAs under general thermomechanical cycling. By\nusing the martensitic volume fraction, transformation strain, internal stress,\nand TRIP strain tensors as internal state variables, the model is capable to\ncapture the stress-dependent TRIP generation when SMAs are subjected to a\nmultiaxial stress state, as well as the TWSME for thermomechanically trained\nSMAs under load-free conditions. A detailed implementation procedure of the\nproposed model is presented through a user-defined material subroutine within a\nfinite element framework allowing for solving different Boundary Value Problems\n(BVPs). Comprehensive instruction on calibrating the model parameters as well\nas the derivation of continuum tangent stiffness matrix are also provided. In\nthe end, the simulated cyclic pseudoelastic and actuation responses by the\npresented model for a wide range of SMA material systems under both uniaxial\nand multiaxial stress states are compared against experimental results to\nvalidate the proposed modeling capabilities."
    },
    {
        "anchor": "Tuning of the hole spin relaxation time in single self-assembled\n  In$_{1-x}$Ga$_x$As/GaAs quantum dots by electric field: We investigate the electric field tuning of the phonon-assisted hole spin\nrelaxation in single self-assembled In$_{1-x}$Ga$_{x}$As/GaAs quantum dots,\nusing an atomistic empirical pseudopotential method. We find that the electric\nfield along the growth direction can tune the hole spin relaxation time for\nmore than one order of magnitude. The electric field can prolong or shorten the\nhole spin lifetime and the tuning shows an asymmetry in terms of the field\ndirection. The asymmetry is more pronounced for the taller the dot. The results\nshow that the electric field is an effective way to tune the hole\nspin-relaxation in self-assembled QDs.",
        "positive": "Steam Degradation of Ytterbium Disilicate Environmental Barrier\n  Coatings: Effect of Composition, Microstructure and Temperature: Recession of environmental barrier coatings (EBC) in environments containing\nsteam is a pressing concern that requires further research before their\nimplementation in gas turbine engines can be realized. In this work,\nfree-standing plasma sprayed Yb2Si2O7 coatings were exposed to flowing steam at\n1350 {\\deg}C and 1400 {\\deg}C for 96 h. Three samples were investigated, one\ncoating with a low porosity level (< 3 %) and 1 wt.% Al2O3 representing\ntraditional EBCs; and two coatings with higher porosity levels (~20 %)\nrepresenting abradable EBCs. Phase composition and microstructural evolution\nwere studied in order to reveal the underlying mechanism for the interaction\nbetween high temperature steam and ytterbium disilicate. The results show\ndepletion of Yb2SiO5 near the surface and formation of ytterbium garnet\n(Yb3Al5O12) on top of all three coatings due to the reaction with gaseous\nAl-containing impurities coming from the alumina furnace tubes. The 1 wt.%\nAl2O3 added to the EBC sample exacerbated the formation of garnet at 1400\n{\\deg}C compared to the abradable samples, which presented lower quantities of\ngarnet. Additionally, inter-splat boundaries were visible after exposure,\nindicating preferential ingress of gaseous Al-containing impurities through the\nsplat boundaries"
    },
    {
        "anchor": "Is N-doped SrO magnetic? A first-principles view: N-doped SrO seems to be one of the model systems for d^0 magnetism, in which\nmagnetism (or ideally, ferromagnetism) was ascribed to the localized N 2p spins\nmediated by delocalized O 2p holes. Here we offer a different view, using\ndensity functional calculations. We find that N-doped SrO with solely\nsubstitutional N impurities as widely assumed in the literature is unstable,\nand instead that a pairing state of substitutional and interstitial N\nimpurities is significantly more stable and has a much lower formation energy\nthan the former by 6.7 eV. The stable (N_{sub}-N_{int})^{2-} dimers behave like\na charged (N_2)^{2-} molecule and have each a molecular spin=1. However, their\nspin-polarized molecular levels lie well inside the wide band gap of SrO and\nthus the exchange interaction is negligibly weak. As a consequence, N-doped SrO\ncould not be ferromagnetic but paramagnetic.",
        "positive": "Optical to UV spectra and birefringence of SiO$_2$ and TiO$_2$:\n  First-principles calculations with excitonic effects: A first principles approach is presented for calculations of optical --\nultraviolet (UV) spectra including excitonic effects. The approach is based on\nBethe-Salpeter equation calculations using the \\textsc{NBSE} code combined with\nground-state density-functional theory calculations from the electronic\nstructure code \\textsc{ABINIT}. Test calculations for bulk Si are presented,\nand the approach is illustrated with calculations of the optical spectra and\nbirefringence of $\\alpha$-phase SiO$_2$ and the rutile and anatase phases of\nTiO$_2$. An interpretation of the strong birefringence in TiO$_2$ is presented."
    },
    {
        "anchor": "Thermal conductivity measurements of PTFE and Al$_2$O$_3$ ceramic at\n  sub-Kelvin temperatures: The design of low temperature bolometric detectors for rare event searches\nnecessitates careful selection and characterization of structural materials\nbased on their thermal properties. We measure the thermal conductivities of\npolytetrafluoroethylene (PTFE) and Al$_2$O$_3$ ceramic (alumina) in the\ntemperature ranges of 0.17-0.43 K and 0.1-1.3 K, respectively. For the former,\nwe observe a quadratic temperature dependence across the entire measured range.\nFor the latter, we see a cubic dependence on temperature above ~0.3 K, with a\nlinear contribution below that temperature. This paper presents our measurement\ntechniques, results, and theoretical discussions. Keywords: Thermal\nConductivity, PTFE, Al$_2$O$_3$ ceramic, Bolometer",
        "positive": "Probing the interface magnetism in the FeMn/NiFe exchange bias system\n  using magnetic second harmonic generation: Second harmonic generation magneto-optic Kerr effect (SHMOKE) experiments,\nsensitive to buried interfaces, were performed on a polycrystalline NiFe/FeMn\nbilayer in which areas with different exchange bias fields were prepared using\n5 KeV He ion irradiation. Both reversible and irreversible uncompensated spins\nare found in the antiferromagnetic layer close to the interface with the\nferromagnetic layer. The SHMOKE hysteresis loop shows the same exchange bias\nfield as obtained from standard magnetometry. We demonstrate that the exchange\nbias effect is controlled by pinned uncompensated spins in the\nantiferromagnetic layer."
    },
    {
        "anchor": "Indirect Mechanism of Au adatom Diffusion on the Si(100) Surface: Calculations of the diffusion of a Au adatom on the dimer reconstructed\nSi(100)-2x1 surface reveal an interesting mechanism that differs significantly\nfrom a direct path between optimal binding sites, which are located in between\ndimer rows. Instead, the active diffusion mechanism involves promotion of the\nadatom to higher energy sites on top of a dimer row and then fast migration\nalong the row, visiting ca. a hundred sites at room temperature, before falling\nback down into an optimal binding site. This top-of-row mechanism becomes more\nimportant the lower the temperature is. The calculations are carried out by\nfinding minimum energy paths on the energy surface obtained from density\nfunctional theory within the PBEsol functional approximation followed by\nkinetic Monte Carlo simulations of the diffusion over a range of temperature\nfrom 200 K to 900 K. While the activation energy for the direct diffusion\nmechanism is calculated to be 0.84 eV, the effective activation energy for the\nindirect mechanism is on average 0.56 eV.",
        "positive": "Tuning the Magnetization of Manganese (II) Carbonate by Intracrystalline\n  Amino Acids: Incorporation of organic molecules into the lattice of inorganic crystalline\nhosts is a common phenomenon in biomineralization, and has been shown to alter\nvarious properties of the crystalline host. Taking this phenomenon as our\nsource of inspiration, we show herein that incorporation of specific single\namino acids into the lattice of manganese (II) carbonate strongly alters its\ninherent magnetic properties. At room temperature, the magnetic susceptibility\nof the amino-acid-incorporating paramagnetic MnCO3 decreases, following a\nsimple rule of mixtures. When cooled below the N\\'eel temperature, however, the\nopposite trend is observed, namely an increase in magnetic susceptibility\nmeasured in a high magnetic field. Such an increase, accompanied by a drastic\nchange in the N'eel phase transformation temperature, results from a decrease\nin MnCO3 orbital overlapping and the weakening of superexchange interactions."
    },
    {
        "anchor": "Compound Defects in Halide Perovskites: A First-Principles Study of\n  CsPbI$_3$: Lattice defects affect the long-term stability of halide perovskite solar\ncells. Whereas simple point defects, i.e., atomic interstitials and vacancies,\nhave been studied in great detail, here we focus on compound defects that are\nmore likely to form under crystal growth conditions, such as compound vacancies\nor interstitials, and antisites. We identify the most prominent defects in the\narchetype inorganic perovskite CsPbI$_3$, through first-principles density\nfunctional theory (DFT) calculations. We find that under equilibrium conditions\nat room temperature, the antisite of Pb substituting Cs forms in a\nconcentration comparable to those of the most prominent point defects, whereas\nthe other compound defects are negligible. However, under nonequilibrium\nthermal and operating conditions, other complexes also become as important as\nthe point defects. Those are the Cs substituting Pb antisite, and, to a lesser\nextent, the compound vacancies of PbI$_2$ or CsPbI$_3$ units, and the I\nsubstituting Cs antisite. These compound defects only lead to shallow or\ninactive charge carrier traps, which testifies to the electronic stability of\nthe halide perovskites. Under operating conditions with a quasi Fermi level\nvery close to the valence band, deeper traps can develop.",
        "positive": "Statistical analysis of the material, geometrical and imperfection\n  characteristics of structural stainless steels and members: Traditional member-based two-step design approaches included in current\nstructural codes for steel structures, as well as more recent system-based\ndirect-design alternatives, require building rigorous structural reliability\nframeworks for the calibration of partial coefficients (resistance factors) to\nachieve specified target reliability requirements. Key design parameters\naffecting the strength of structures and their random variations are generally\nmodelled by nominal or characteristic values in design standards, which are\ncombined with partial coefficients that need to be calibrated from measurements\non real samples. While the statistical characterization of material and\ngeometric properties of structural steels has been consolidated over the last\ndecades, information about the characterization of structural stainless steels\nis virtually non-existent due to the limited pool of available data. Thus, this\npaper presents the basic ingredient for developing reliability frameworks for\nstainless steel structures and components by statistically characterizing the\nmain random parameters affecting their strength through a comprehensive\ndatabase collected from the literature. Based on the collected data,\nappropriate probabilistic models are proposed for geometric properties,\nmaterial properties, imperfections and residual stresses of different stainless\nsteel alloys and cross-section or product types. The data is equally applicable\nto member-based reliability analyses as described in existing codes and\nsystem-based analyses targeted at the direct-design of stainless steel\nstructures by advanced analysis."
    },
    {
        "anchor": "$GW$100: a plane wave perspective for small molecules: In a recent work, van Setten and coworkers have presented a carefully\nconverged $G_0W_0$ study of 100 closed shell molecules [J. Chem. Theory Comput.\n11, 5665 (2015)]. For two different codes they found excellent agreement to\nwithin few 10 meV if identical Gaussian basis sets were used. We inspect the\nsame set of molecules using the projector augmented wave method and the Vienna\nab initio simulation package (VASP). For the ionization potential, the basis\nset extrapolated plane wave results agree very well with the Gaussian basis\nsets, often reaching better than 50 meV agreement. In order to achieve this\nagreement, we correct for finite basis set errors as well as errors introduced\nby periodically repeated images. For electron affinities below the vacuum level\ndifferences between Gaussian basis sets and VASP are slightly larger. We\nattribute this to larger basis set extrapolation errors for the Gaussian basis\nsets. For quasi particle (QP) resonances above the vacuum level, differences\nbetween VASP and Gaussian basis sets are, however, found to be substantial.\nThis is tentatively explained by insufficient basis set convergence of the\nGaussian type orbital calculations as exemplified for selected test cases.",
        "positive": "FIM tips in SPM: Apex orientation and temperature considerations on atom\n  transfer and diffusion: Atoms transferred to W(111) and W(110) tip apices from the Au(111) surface\nduring tunneling and approach to mechanical contact experiments in STM are\ncharacterized in FIM at room temperature and at 158 K. The different activation\nenergies for diffusion on the (111) and (110) tip planes and the experiment\ntemperature are shown to be important factors controlling the extent of changes\nto the atomic structure of the tip. W(111) tips are much better suited to\nscanning probe studies which require the characterization of an atomically\ndefined tip and subsequent verification of its integrity in FIM. The statistics\nof the observed spikes in the tunneling current when the tips are approached to\nAu(111) are interpreted using a simple model of adatoms diffusing through the\nSTM junction."
    },
    {
        "anchor": "Crystal nucleation and cluster-growth kinetics in a model glass under\n  shear: Crystal nucleation and growth processes induced by an externally applied\nshear strain in a model metallic glass are studied by means of nonequilibrium\nmolecular dynamics simulations, in a range of temperatures. We observe that the\nnucleation-growth process takes place after a transient, induction regime. The\ncritical cluster size and the lag-time associated with this induction period\nare determined from a mean first-passage time analysis. The laws that describe\nthe cluster growth process are studied as a function of temperature and strain\nrate. A theoretical model for crystallization kinetics that includes the time\ndependence for nucleation and cluster growth is developed within the framework\nof the Kolmogorov-Johnson-Mehl-Avrami scenario and is compared with the\nmolecular dynamics data. Scalings for the cluster growth laws and for the\ncrystallization kinetics are also proposed and tested. The observed nucleation\nrates are found to display a nonmonotonic strain rate dependency.",
        "positive": "Dark Field X-ray Microscopy Below Liquid-Helium Temperature: The Case of\n  NaMnO2: Dark field X-ray microscopy (DFXM) is an experimental technique employed to\ninvestigate material properties by probing their 'mesoscale,' or microscale\nstructures, in a bulk-sensitive manner using hard X-rays at synchrotron\nradiation sources. However, challenges remain when it comes to applications of\nthis technique to examine low-temperature phenomena in quantum materials, which\nexhibit complex phase transitions at cryogenic temperatures. One such material\nis NaMnO2, which hosts an antiferromagnetic transition at 45 K that is\nsuspected to coincide with local structural transitions from its majority\nmonoclinic phase to nanoscale triclinic domains. Direct observation of local\nheterogeneities and this effect at low temperatures in NaMnO2 is an important\nstep in understanding this material, and serves as an ideal candidate study for\nexpanding the DFXM experimental design space. This paper details a foundational\nhigh-resolution DFXM study, down to liquid-helium temperature and below,\nconducted to explore phase transitions in NaMnO2. The outlined experiment\nushers in the evaluation of other functional materials at low temperatures\nusing this technique."
    },
    {
        "anchor": "Near Field Scanning Optical Imaging of Gold Nanoparticles in the\n  Sub-Wavelength Limit: The near-field scanning optical microscopic (NSOM) imaging of Au\nnanoparticles with size in the sub-wavelength limit (<wavelength/2N.A.) is\nreported. The NSOM imaging technique can resolve the objects which is beyond\nthe scope of optical microscope using visible light (wavelength=500 nm) with\nobjectives having a numerical aperture (N.A.) close to unity. The role of\nevanescent waves which is an exponentially decaying field with higher momenta\ni.e., lower wavelengths compared to that of normal light, in the metal\ndielectric interface is realized for imaging of noble metal nanostructures with\nsub-wavelength dimension in the near field. However, the confined light with\ncomponents of evanescent waves, emanating from the NSOM probe, interacts with\nthe oscillating dipoles present in the sub-diffraction limited nanostructures\nand produce propagating waves, which can be recorded by the far field detector.\nThe light-matter interactions of Au nanoparticles of diameters in the range of\n10-150 nm probed by the NSOM technique with a visible excitation of 532 nm are\nreported. The strong surface plasmon resonance (SPR) related absorption of Au\nnanoparticles is envisaged for explaining the contrast variations in the\nrecorded NSOM images.",
        "positive": "Influence of Annealing Conditions on Structure and Optical Properties of\n  Copper Nanoparticles Embedded in Silica Matrix: Copper nanoparticles have been grown in silica matrix by annealing of the\nsol-gel prepared porous matrix impregnated with the copper nitrate. The\nannealing has been performed in air, successively in air and hydrogen, and in\nhydrogen. Cu nanoparticles in size range of 2-65 nm have been grown depending\non annealing conditions. Annealing in air results in copper oxide nanoparticles\n(Cu2O) growth as well. Transmission electron microscopy (TEM) and optical\nspectroscopy of the copper nanoparticles in silica matrix have been performed.\nThe copper nanoparticles of two types are grown: spherical mature particles and\nelliptical seed particles. The surface plasmon peak has been observed clearly\nin absorption spectra of Cu nanoparticles. Surface plasmon peak in absorption\nspectra of Cu nanoparticles demonstrates slight blue shift with decrease of the\nparticle size. The half-width of the surface plasmon peak decreases appreciably\nat the lowering of temperature from 293 K to 77 and 4.2K that is due to strong\nelectron-phonon interaction. The low-frequency Raman scattering data are in\nagreement with electron microscopy and absorption data. Photoluminescence from\nthe copper nanoparticles has been observed. Efficiency of the luminescence\nincreases appreciably at the decrease of particle size. The observed increase\nis explained, probably, by the coupling of the excited incoming and outgoing\nemitted photons with surface plasmon."
    },
    {
        "anchor": "Ultra-low lattice thermal conductivity induces high-performance\n  thermoelectricity in Janus group-VIA binary monolayers: In this paper, the electrical transport, thermal transport, and\nthermoelectric properties of three new Janus STe$_{2}$, SeTe$_{2}$, and\nSe$_{2}$Te monolayers are systematically studied by first-principles\ncalculations, as well as the comparative with available literature's results\nusing different methods. It is found that the Seebeck coefficient and\nconductivity have opposite dependence on temperature, and we illustrate this\nphenomenon in detail. The decrease of the thermoelectric power factor (PF) with\ntemperature originates from the decrease in conductivity. To obtain accurate\nand convergent lattice thermal conductivity, the root mean square (RMS) is\ncalculated to obtain a reasonable cutoff radius for the calculation of\nthird-order forces. Janus STe$_{2}$, SeTe$_{2}$, and Se$_{2}$Te monolayers\nexhibit ultra-low lattice thermal conductivity of 0.2, 0.133, and\n4.81$\\times10^{-4}$ W/mK at 300 K, which result from the strong coupling effect\nbetween the acoustic mode and the low-frequency optical branch, low phonon\ngroup velocity, small phonon lifetime, and large anharmonicity. Consequently,\nultra-high $\\textit{ZT}$ values of 2.11 (2.09), 3.28 (4.24), and 3.40 (6.51)\nfor n-type(p-type) carrier doping of STe$_{2}$, SeTe$_{2}$, and Se$_{2}$Te are\nobtained, indicating that they are promising thermoelectric materials.",
        "positive": "Understanding magnetoelectric switching in BiFeO$_3$ thin films: In this work we use a phenomenological theory of ferroelectric switching in\nBiFeO$_3$ thin films to uncover the mechanism of the two-step process that\nleads to the reversal of the weak magnetization of these materials. First, we\nintroduce a realistic model of a BiFeO$_3$ film, including the Landau energy of\nisolated domains as well as the constraints that account for the presence of\nthe substrate and the multidomain configuration found experimentally. We use\nthis model to obtain statistical information about the switching behavior - by\nrunning dynamical simulations based on the Landau-Khalatnikov time-evolution\nequation, including thermal fluctuations - and we thus identify the factors\nthat drive the two-step polarization reversal observed in the experiments.\nAdditionally, we apply our model to test potential strategies for optimizing\nthe switching characteristics."
    },
    {
        "anchor": "Synthesis and structural/microstructural characteristics of antimony\n  doped tin oxide $(Sn_{1-x}Sb_{x}O_{2-\u03b4})$: Bulk samples of $(Sn_{1-x}Sb_{x}O_{2-\\delta})$ with x = 0.00, 0.10, 0.20,\n0.30 are synthesized by solid-state reaction route. Samples were characterized\nby X-ray powder diffraction (XRD), scanning electron microscopy (SEM),\ntransmission electron microscopy (TEM) and UV-Vis spectroscopy. The x-ray\ndiffraction patterns indicate that the gross structure/phase of $(Sn_{1-x}$\n$Sb_{x}O_{2-\\delta})$ do not change with the substitution of antimony (Sb) up\nto x = 0.30. The surface morphological examination with SEM revealed the fact\nthat the grain size in the antimony doped sample is larger than that of undoped\none and hence pores/voids between the grains increase with Sb concentration up\nto 0.30. TEM image of undoped sample indicates that the $SnO_{2}$ grains have\ndiameters ranging from 25 to 120 nm and most grains are in cubic or spherical\nshape. As antimony content increases, the nanocubes/spheres are converted into\nmicrocubes/spheres. The reflectance of $Sn_{1-x}Sb_{x}O_{2-\\delta}$ samples\nincreases whereas absorbance of these samples decreases with the increased\nconcentration of antimony (Sb) for the wavelength range 360 - 800 nm. The\nenergy bandgap of Sb doped - $SnO_{2}$ samples were obtained from optical\nabsorption spectra by UV-Vis absorption spectroscopy. Upon increasing the Sb\nconcentration the bandgap of the samples was found to increase from 3.367 eV to\n3.558 eV.",
        "positive": "Is it possible to grow amorphous normal nanosprings ?: Nanosprings have been object of intense investigations in recent years. They\ncan be classified as normal or binormal depending on the geometry of their\ncross-section. Normal amorphous nanosprings have not been observed\nexperimentally up to now, and only recently the synthesis of a crystalline ZnO\nnormal nanohelix has been reported. We discuss the shape of the catalyst in\nterms of the cross-sectional shape of the nanospring, and show that, within the\nvapor-liquid-solid model, the growth of amorphous normal nanospring is not\nenergetically favoured."
    },
    {
        "anchor": "A functional renormalization group approach to electronic structure\n  calculations for systems without translational symmetry: A formalism for electronic-structure calculations is presented that is based\non the functional renormalization group (FRG). The traditional FRG has been\nformulated for systems that exhibit a translational symmetry with an associated\nFermi surface, which can provide the organization principle for the\nrenormalization group (RG) procedure. We here advance an alternative\nformulation, where the RG-flow is organized in the energy-domain rather than in\nk-space. This has the advantage that it can also be applied to inhomogeneous\nmatter lacking a band-structure, such as disordered metals or molecules. The\nenergy-domain FRG ({\\epsilon}FRG) presented here accounts for Fermi-liquid\ncorrections to quasi-particle energies and particle-hole excitations. It goes\nbeyond the state of the art GW-BSE, because in {\\epsilon}FRG the Bethe-Salpeter\nequation (BSE) is solved in a self-consistent manner. An efficient\nimplementation of the approach that has been tested against exact\ndiagonalization calculations and calculations based on the density matrix\nrenormalization group is presented.\n  Similar to the conventional FRG, also the {\\epsilon}FRG is able to signalize\nthe vicinity of an instability of the Fermi-liquid fixed point via runaway flow\nof the corresponding interaction vertex. Embarking upon this fact, in an\napplication of {\\epsilon}FRG to the spinless disordered Hubbard model we\ncalculate its phase-boundary in the plane spanned by the interaction and\ndisorder strength. Finally, an extension of the approach to finite temperatures\nand spin S = 1/2 is also given.",
        "positive": "Electron doping induced stable ferromagnetism in two-dimensional GdI_3\n  monolayer: As a two-dimensional material with a hollow hexatomic ring structure,\nN\\'eel-type anti-ferromagnetic (AFM) GdI3 can be used as a theoretical model to\nstudy the effect of electron doping. Based on first-principles calculations, we\nfind that the Fermi surface nesting occurs when more than 1/3 electron per Gd\nis doped, resulting in the failure to obtain a stable ferromagnetic (FM) state.\nMore interestingly, GdI3 with appropriate Mg/Ca doping (1/6 Mg/Ca per Gd) turns\nto be half-metallic FM state. This AFM-FM transition results from the transfer\nof doped electrons to the spatially expanded Gd-5d orbital, which leads to the\nFM coupling of local half-full Gd-4f electrons through 5d-4f hybridization.\nMoreover, the shortened Gd-Gd length is the key to the formation of the stable\nferromagnetic coupling. Our method provides new insights into obtaining stable\nFM materials from AFM materials."
    },
    {
        "anchor": "Disruption of the $sp^2$ bonding by the compression of the\n  $\u03c0$-electronic orbitals of graphene at various stacking orders: We investigate the behaviour of the $\\pi$-electrons under compression and the\neffect of the stacking order of graphene layers. First we find that electrons\ncan hardly be squeezed through the $sp^2$ network, regardless of the stacking\norder. The largely deformed electronic orbitals (mainly those of\n$\\pi$-electrons) under compression along the $\\textit{c}$-axis increase\ninterlayer interaction between graphene layers as expected, but surprisingly in\na similar way for the A-A and Bernal stacking. On the other hand, the large\nout-of-plane compression shifts the in-plane phonon frequencies of A-A stacked\ngraphene layers significantly and very differently from Bernal stacked layers.\nWe attribute these results to the $sp^2$-electrons filling the low-density\ncentral area in a carbon hexagon under compression for the A-A stacking, hence\nresulting in a non-monotonic change of the $sp^2$-bonding. The results strongly\nsuggest not to ignore 3D features of a 2D material.",
        "positive": "The thermodynamic and kinetic properties of hydrogen dimers on graphene: The thermodynamic and kinetic properties of hydrogen adatoms on graphene are\nimportant to the materials and devices based on hydrogenated graphene. Hydrogen\ndimers on graphene with coverages varying from 0.040 to 0.111 ML (1.0 ML $=\n3.8\\times10^{15}$cm$^{-2}$) were considered in this report. The thermodynamic\nand kinetic properties of H, D and T dimers were studied by ab initio\nsimulations. The vibrational zero-point energy corrections were found to be not\nnegligible in kinetics, varying from 0.038 (0.028, 0.017) to 0.257 (0.187,\n0.157) eV for H (D, T) dimers. The isotope effect exhibits as that the kinetic\nmobility of a hydrogen dimer decreases with increasing the hydrogen mass. The\nsimulated thermal desorption spectra with the heating rate $\\alpha = 1.0$ K/s\nwere quite close to experimental measurements. The effect of the interaction\nbetween hydrogen dimers on their thermodynamic and kinetic properties were\nanalyzed in detail."
    },
    {
        "anchor": "Hyperfine tensors of nitrogen-vacancy center in diamond from \\emph{ab\n  initio} calculations: We determine and analyze the charge and spin density distributions of\nnitrogen-vacancy (N-V) center in diamond for both the ground and excited states\nby \\emph{ab initio} supercell calculations. We show that the hyperfine tensor\nof $^{15}$N nuclear spin is negative and strongly anisotropic in the excited\nstate, in contrast to previous models used extensively to explain electron spin\nresonance measurements. In addition, we detect a significant redistribution of\nthe spin density due to excitation that has serious implications for the\nquantum register applications of N-V center.",
        "positive": "Recombination of radiation defects in solid methane - neutron sources\n  and cryo-volcanism on celestial bodies: Physicochemical properties of solid methane exposed to ionizing radiation\nhave attracted significant interest in recent years. Here we present new trends\nin the study of radiation effects in solid methane. We particularly focus on\nrelaxation phenomena in solid methane pre-irradiated by energetic neutrons and\nelectron beam. We compare experimental results obtained in the temperature\nrange from 10K to 100K with a model based on the assumption that radiolysis\ndefect recombinations happen in two stages, at two different temperatures. In\nthe case of slow heating up of the solid methane sample, irradiated at 10K, the\nfirst wave of recombination occurs around 20K with a further second wave taking\nplace between 50 and 60K. We also discuss the role of the recombination\nmechanisms in burp phenomenon discovered by J. Carpenter in the late 1980s. An\nunderstanding of these mechanisms is vital for the designing and operation of\nsolid methane moderators used in advanced neutron sources and could also be a\npossible explanation for the driving forces behind cryo-volcanism on celestial\nbodies."
    },
    {
        "anchor": "Magnetic properties of the helimagnet Cr1/3NbS2 observed by muSR: We have performed muon spin rotation/relaxation (muSR) measurements on single\ncrystals of the chiral helimagnet Cr1/3NbS2 at zero to low magnetic field. The\ntransition from the paramagnetic to helical magnetically ordered phase at zero\nfield is marked by the onset of a coherent oscillation of the zero-field muon\nspin polarization below a critical temperature Tc. An enhancement of the muon\nspin precession frequency is observed below T ~ 50K, where anomalous behavior\nhas been observed in bulk transport measurements. The enhanced precession\nfrequency indicates a low-temperature modification of the helical magnetic\nstructure. A Landau free energy analysis suggests that the low-temperature\nchange in the magnetic structure is caused by a structural change, whereas the\nmagnetic order above Tc is the result of an attractive interaction between the\nferromagnetic moment induced by the applied field and the magnetic moments of\nthe helical structure. We also suggest a longer periodicity of helicity below T\n~ 50K, which can be verified by neutron scattering.",
        "positive": "Different Photostability of BiVO4 in Near-pH-Neutral Electrolytes: Photoelectrochemical water splitting is a promising route to produce hydrogen\nfrom solar energy. However, corrosion of semiconducting photoelectrodes remains\na fundamental challenge for their practical application. The stability of\nBiVO4, one of the best performing photoanode materials, is systematically\nexamined here using an illuminated scanning flow cell to measure its\ndissolution operando. The dissolution rates of BiVO4 under illumination depend\non the electrolyte and decrease in the order: borate (pH=9.3) > phosphate\n(pH=7.2) > citrate (pH=7.0). BiVO4 exhibits an inherent lack of stability\nduring the oxygen evolution reaction (OER), while hole-scavenging citrate\nelectrolyte offers kinetic protection. The dissolution of Bi peaks at different\npotentials than the dissolution of V in phosphate buffer, whereas both ions\ndissolve simultaneously in borate buffer. The life cycle of a 90 nm BiVO4 film\nis monitored during one hour of light-driven OER in borate buffer. The\nphotocurrent and dissolution rates show independent trends with time,\nhighlighting the importance to measure both quantities operando. Dissolution\nrates are correlated to the surface morphology and chemistry characterized\nusing electron microscopy, X-ray photoelectron spectroscopy and atom probe\ntomography. These correlative measurements further the understanding on\ncorrosion processes of photoelectrodes down to the nanoscopic scale to\nfacilitate their future developments."
    },
    {
        "anchor": "Crystal field coefficients for yttrium analogues of\n  rare-earth/transition-metal magnets using density-functional theory in the\n  projector-augmented wave formalism: We present a method of calculating crystal field coefficients of\nrare-earth/transition-metal (RE-TM) magnets within density-functional theory\n(DFT). The principal idea of the method is to calculate the crystal field\npotential of the yttrium analogue (\"Y-analogue\") of the RE-TM magnet, i.e. the\nmaterial where the lanthanide elements have been substituted with yttrium. The\nadvantage of dealing with Y-analogues is that the methodological and conceptual\ndifficulties associated with treating the highly-localized 4f electrons in DFT\nare avoided, whilst the nominal valence electronic structure principally\nresponsible for the crystal field is preserved. In order to correctly describe\nthe crystal field potential in the core region of the atoms we use the\nprojector-augmented wave formalism of DFT, which allows the reconstruction of\nthe full charge density and electrostatic potential. The Y-analogue crystal\nfield potentials are combined with radial 4f charge densities obtained in\nself-interaction-corrected calculations on the lanthanides to obtain crystal\nfield coefficients. We demonstrate our method on a test set of 10 materials\ncomprising 9 RE-TM magnets and elemental Tb. We show that the calculated easy\ndirections of magnetization agree with experimental observations, including a\ncorrect description of the anisotropy within the basal plane of Tb and\nNdCo$_5$. We further show that the Y-analogue calculations generally agree\nquantitatively with previous calculations using the open-core approximation to\ntreat the 4f electrons, and argue that our simple approach may be useful for\nlarge-scale computational screening of new magnetic materials.",
        "positive": "Structural properties of Co$_{2}$TiSi films on GaAs(001): Co$_{2}$TiSi films were grown by molecular beam epitaxy on GaAs(001) and\nanalyzed using reflection high-energy electron diffraction, and electron\nmicroscopy. In addition, X-ray diffraction was combined with lattice parameter\ncalculations by density functional theory comparing the \\textit{L$2_1$} and\n\\textit{B}2 structures and considering the influence of non--stoichiometry.\nColumnar growth is found and attributed to inhomogeneous epitaxial strain from\nnon-random alloying. In films with thicknesses up to 13~nm these columns may be\nthe origin of perpendicular magnetization with the easy axis perpendicular to\nthe sample surface. We found \\textit{L$2_1$} and \\textit{B}2 ordered regions,\nhowever the [Co]/[Ti]--ratio is changing in dependence of the position in the\nfilm. The resulting columnar structure is leading to anisotropic\n\\textit{B}2--ordering with the best order parallel to the axes of the columns."
    },
    {
        "anchor": "Termination control of electronic phases in oxide thin films and\n  interfaces: LaAlO3/SrTiO3(001): A wealth of intriguing properties emerge in the seemingly simple system\ncomposed of the band insulators LaAlO3 and SrTiO3 such as a two-dimensional\nelectron gas, superconductivity and magnetism. In this paper we review the\ncurrent insight obtained from first principles calculations on the mechanisms\ngoverning the behavior of thin LaAlO3 films on SrTiO3(001). In particular, we\nexplore the strong dependence of the electronic properties on the surface and\ninterface termination, the finite film thickness, lattice polarization and\ndefects. A further aspect that is addressed is how the electronic behavior and\nfunctionality can be tuned by a SrTiO3 capping layer, adsorbates and metallic\ncontacts. Lastly, we discuss recent reports on the coexistence of magnetism and\nsuperconductivity in this system for what they might imply about the electronic\nstructure of this system.",
        "positive": "Anion-Anion Bonding and the Topology in Ternary Iridium Seleno-Stannides: The synthesis and physical properties of two new and one known Ir-Sn-Se\ncompound are reported. Their crystal structures are elucidated with\ntransmission electron microscopy and powder X-ray diffraction. IrSn0.45Se1.55\nis a pyrite phase which consists of tilted corner-sharing IrX6 octahedra with\nrandomly distributed (Sn-Se)4- and (Se-Se)2- dimers. Ir2Sn3Se3 is a trigonally\ndistorted skutterudite that consists of cooperatively tilted corner-sharing\nIrSn3Se3 octahedra with ordered (Sn-Se)24- tetramers. Ir2SnSe5 is a layered,\ndistorted \\b{eta}-MnO2 (pyrolusite) structure consisting of a double IrSe6\noctrahedral row, corner-sharing in the a direction and edge-sharing in the b\ndirection. This distorted pyrolusite contains (Se-Se)2- dimers, Se2- anions,\nand each double row is \"capped\" with a (Sn-Se)n polymeric chain. Resistivity,\nspecific heat, and magnetization measurements show that all three have\ninsulating and diamagnetic behavior, indicative of low spin 5d6 Ir3+.\nElectronic structure calculations on Ir2Sn3Se3 show a single, spherical,\nnon-spin-orbit split valence band, and suggest that Ir2Sn3Se3 is topologically\nnon-trivial under tensile strain, due to inversion of Ir-d and Se-p states."
    },
    {
        "anchor": "First-Principles Prediction of Two-Dimensional B3C2P3 and B2C4P2:\n  Structural Stability, Fundamental Properties, and Renewable Energy\n  Applications: The existence of two novel hybrid two-dimensional (2D) monolayers, 2D B3C2P3\nand 2D B2C4P2, has been predicted based on the density functional theory\ncalculations. It has been shown that these materials possess structural and\nthermodynamic stability. 2D B3C2P3 is a moderate band gap semiconductor, while\n2D B2C4P2 is a zero band gap semiconductor. It has also been shown that 2D\nB3C2P3 has a highly tunable band gap under the effect of strain and substrate\nengineering. Moreover, 2D B3C2P3 produces low barriers for dissociation of\nwater and hydrogen molecules on its surface, and shows fast recovery after\ndesorption of the molecules. The novel materials can be fabricated by carbon\ndoping of boron phosphide, and directly by arc discharge and laser ablation and\nvaporization. Applications of 2D B3C2P3 in renewable energy and straintronic\nnanodevices have been proposed.",
        "positive": "Nonequilibrium Polaritonics - Nonlinear Effects and Optical Switching: We report a theoretical non-equilibrium description of polaritonics and we\npropose ultrafast all- optical switching due to highly nonlinear polaritonics.\nThe electronic band structure within gold (Au) nano grains is modified by\nexternal laser light. The Au grains are coupled to a single mode photonic\nwaveguide and we derive a strong transmission reduction of switching\noriginating from the establishd quantum interference with a finite lifetime."
    },
    {
        "anchor": "Polarization characteristics of adatoms self-diffusing on metal surfaces\n  under high electric fields: Although atomic diffusion on metal surfaces under high electric fields has\nbeen studied theoretically and experimentally since the 1970s, its accurate and\nquantitative theoretical description remains a significant challenge. In our\nprevious work, we developed a theoretical framework that describes the atomic\ndynamics on metal surfaces in the presence of an electric field in terms of the\nlocal polarization characteristics of the surface at the vicinity of a moving\natom. Here, we give a deeper analysis of the physics underlying this framework,\nintroducing and rigorously defining the concept of the effective polarization\ncharacteristics (permanent dipole moment $\\mu$ and polarizability $\\alpha$) of\na moving atom on a metal surface, which are shown to be the relevant atomic\nquantities determining the dynamics of a moving atom via a compact equation. We\nuse density functional theory (DFT) to calculate $\\mu$ and $\\alpha$ of a W\nadatom moving on a W {110} surface, where additional adatoms are present in its\nvicinity. We analyze the dependence of $\\mu$ and $\\alpha$ and hence the\nmigration barriers under electric fields on the local atomic environments (LAE)\nof an adatom. We find that the LAE significantly affects $\\mu$ and $\\alpha$ of\na moving atom in the limited cases we studied, which implies that further\nsystematic DFT calculations are needed to fully parameterize surface diffusion\nin terms of energy barriers for long-term large scale simulations, such as our\nrecently developed Kinetic Monte Carlo model for surface diffusion under\nelectric field.",
        "positive": "Impact of Four-Valent Doping on the Crystallographic Phase Formation for\n  Ferroelectric HfO$_2$ from First-Principles: Implications for Ferroelectric\n  Memory and Energy-Related Applications: The ferroelectric properties of nanoscale silicon doped HfO$_2$ promise a\nmultitude of applications ranging from ferroelectric memory to energy-related\napplications. The reason for the unexpected behavior has not been clearly\nproven and presumably include contributions from size effects and doping\neffects. Silicon incorporation in HfO$_2$ is investigated computationally by\nfirst-principles using different density functional theory (DFT) methods.\nFormation energies of interstitial and substitutional silicon in HfO$_2$ paired\nwith and without an oxygen vacancy prove the substitutional defect as the most\nlikely. Within the investigated concentration window up to 12.5 formula unit %,\nsilicon doping alone is not sufficient to stabilize the polar and orthorhombic\ncrystal phase (p-o-phase), which has been identified as the source of the\nferroelectricity in HfO$_2$. On the other hand, silicon incorporation is one of\nthe strongest promoters of the p-o-phase and the tetragonal phase (t-phase)\nwithin the group of investigated dopants, confirming the experimental\nferroelectric window. Besides silicon, the favoring effects on the energy of\nother four-valent dopants, C, Ge, Ti, Sn, Zr and Ce, are examined, revealing Ce\nas a very promising candidate. The evolution of the volume changes with\nincreasing doping concentration of these four-valent dopants shows an inverse\ntrend for Ce in comparison to silicon. To complement this study, the\ngeometrical incorporation of the dopants in the host HfO$_2$ lattice was\nanalyzed."
    },
    {
        "anchor": "Can magneto-transport properties provide insight into the functional\n  groups in semiconducting MXenes?: The Hall scattering factor of Sc2CF2, Sc2CO2 and Sc2C(OH)2 is calculated\nusing Rode's iterative approach by solving the Boltzmann transport equation.\nThis is carried out in conjunction with calculations based on density\nfunctional theory. The electrical transport in Sc2CF2, Sc2CO2, and Sc2C(OH)2 is\nmodelled by accounting for both elastic (acoustic and piezoelectric) and\ninelastic (polar optical phonon) scattering. Polar optical phonon (POP)\nscattering is the most significant mechanism in these MXenes. We observe that\nthere is a window of carrier concentration where Hall factor acts dramatically;\nSc2CF2 obtains an incredible high value of 2.49 while Sc2CO2 achieves a very\nsmall value of approximately 0.5, and Sc2C(OH)2 achieves the so called ideal\nvalue of 1. We propose in this paper that such Hall factor behaviour has\nsignificant promise in the field of surface group identification in MXenes, an\nissue that has long baffled researchers.",
        "positive": "Aluminum oxide nucleation in the early stages of atomic layer deposition\n  on epitaxial graphene: In this work, the nucleation and growth mechanism of aluminum oxide (Al2O3)\nin the early stages of the direct atomic layer deposition (ALD) on monolayer\nepitaxial graphene (EG) on silicon carbide (4H-SiC) has been investigated by\natomic force microscopy (AFM) and Raman spectroscopy. Contrary to what is\ntypically observed for other types of graphene, a large and uniform density of\nnucleation sites was observed in the case of EG and ascribed to the presence of\nthe buffer layer at EG/SiC interface. The deposition process was characterized\nby Al2O3 island growth in the very early stages, followed by the formation of a\ncontinuous Al2O3 film (2.4 nm thick) after only 40 ALD cycles due to the\nislands coalescence, and subsequent layer-by-layer growth. Raman spectroscopy\nanalyses showed low impact of the ALD process on the defects density and doping\nof EG. The EG strain was also almost unaffected by the deposition in the regime\nof island growth and coalescence, whereas a significant increase was observed\nafter the formation of a compact Al2O3 film. The obtained results can have\nimportant implications for device applications of epitaxial graphene requiring\nthe integration of ultra-thin high-k insulators."
    },
    {
        "anchor": "Re-discovering micro-emulsion electrolytes: a biphasic electrolyte\n  platform for Organic redox flow batteries: Redox flow batteries (RFBs) have gained popularity as large-scale energy\nstorage systems for wind and solar powered grids. Modern RFB systems are based\non highly corrosive and/or flammable electrolytes. Organic redox active species\nfor RFBs are gaining commercial traction, but there is a trade-off in choosing\naqueous or non-aqueous electrolytes in terms of rate capabilities, energy\ndensity, safety and cost. While modification of organic redox molecules to\nmitigate these issues is prevalent in the literature, the search for novel\nelectrolyte systems is scarce. Here we present microemulsion-based electrolytes\nas an alternative for the next generation of organic RFBs. Micro-emulsion\nelectrolytes (MEs) offer the advantages of decoupled solubility and ionic\nconductivity, broad electrochemical windows, non-flammability, simple\nfabrication modes and low cost of constituent chemicals. The electrochemical\nproperties of organic redox species in MEs have been investigated for RFB\nrequirements and a proof-of-concept flow cell with a widely studied redox\nsystem and a commercial membrane is shown. The compositions of MEs can be\ntailored to the redox system, making them a platform of electrolytes for all\norganic redox systems under consideration and benefit.",
        "positive": "On performance of thin-film meso-structured perovskite solar cell\n  through experimental analysis and device simulation: In the last few years there is an unprecedented progress in the increase of\nthe power conversion efficiency of perovskite solar cells. Evidently, further\nadvances of the efficiency of these devices will depend on the constraints\nimposed by the optical and electronic properties of their constituents. Quite\napparently that during the manufacturing process of a solar cell, there is an\ninevitable variation in the thicknesses of various functional layers, which\naffects the optoelectronic characteristics of the final sample. In this work a\npossible strategy of the analysis of the solar cell performance is suggested,\nbased on statistically averaging procedure of experimental data. We present a\ncase study, in which the optoelectronic properties of the meso-structured\nperovskite solar cell (with a mesoporous TiO$_2$ layer) are analysed within the\nmethod providing a deeper understanding of the device operation. This method\nenables an assessment of the overall quality of the device, pointing pathways\ntowards the maximum efficiency design of a perovskite solar cell by material\nproperties tuning."
    },
    {
        "anchor": "Functionalizing graphene by embedded boron clusters: We present a model system that might serve as a blueprint for the controlled\nlayout of graphene based nanodevices. The systems consists of chains of B7\nclusters implanted in a graphene matrix, where the boron clusters are not\ndirectly connected. We show that the graphene matrix easily accepts these\nalternating boron chains, and that the implanted boron components may\ndramatically modify the electronic properties of graphene based nanomaterials.\nThis suggests a functionalization of graphene nanomaterials, where the\nsemiconducting properties might be supplemented by parts of the graphene matrix\nitself, but the basic wiring will be provided by alternating chains of\nimplanted boron clusters that connect these areas.",
        "positive": "Communication: Charge-Population Based Dispersion Interactions for\n  Molecules and Materials: We introduce a system-independent method to derive effective atomic C$_6$\ncoefficients and polarizabilities in molecules and materials purely from charge\npopulation analysis. This enables the use of dispersion-correction schemes in\nelectronic structure calculations without recourse to electron-density\npartitioning schemes and expands their applicability to semi-empirical methods\nand tight-binding Hamiltonians. We show that the accuracy of our method is en\npar with established electron-density partitioning based approaches in\ndescribing intermolecular C$_6$ coefficients as well as dispersion energies of\nweakly bound molecular dimers, organic crystals, and supramolecular complexes.\nWe showcase the utility of our approach by incorporation of the recently\ndeveloped many-body dispersion (MBD) method [Tkatchenko et al., Phys. Rev.\nLett. 108, 236402 (2012)] into the semi-empirical Density Functional\nTight-Binding (DFTB) method and propose the latter as a viable technique to\nstudy hybrid organic-inorganic interfaces."
    },
    {
        "anchor": "Stability of Implanted Transition Metal Dopants in Rock-salt Oxides: Transition metals (TMs) implanted in oxides with rock-salt crystal structures\n(for example MgO and BaO) are assumed to substitute cations (Mg in case of MgO)\nfrom the lattice sites. We show that not all implanted TMs substitute cations\nbut can be stable in interstitial sites as well. Stability of TM (Sc--Zn)\ndopants in various charge states in MgO and BaO has been investigated in the\nframework of density functional theory. We propose an effective way to\ncalculate stability of implanted metals that let us predict site preference\n(interstitial or substitution) of the dopant in the host. We find that two\nfactors govern the preference for an interstitial site: i) relative ionic\nradius and ii) relative oxygen affinity of cation and the TM dopants. If the\nradius of the cation is much larger than TM dopant, as in BaO, TM atoms always\nsit at interstitial sites. On the other hand, if the radius of the cation is\ncomparable to that of the dopant TM, as in case of MgO, the transition of the\npreferred defect site, from substituting lattice Mg atom (Sc to Mn) to\noccupying interstitial site (Fe to Zn) is observed. This transition can be\nattributed to the change in the oxygen affinity of the TM atoms from Sc to Zn.\nOur results also explain experiments on Ni and Fe atoms implanted in MgO. This\nis the first-time we have shown that TM dopants can be stable at interstitial\nsites in stable compounds, which could potentially give rise to exotic\nproperties.",
        "positive": "Optical fingerprint of non-covalently functionalized transition metal\n  dichalcogenides: Atomically thin transition metal dichalcogenides (TMDs) hold promising\npotential for applications in optoelectronics. Due to their direct band gap and\nthe extraordinarily strong Coulomb interaction, TMDs exhibit efficient\nlight-matter coupling and tightly bound excitons. Moreover, large spin orbit\ncoupling in combination with circular dichroism allows for spin and valley\nselective optical excitation. As atomically thin materials, they are very\nsensitive to changes in the surrounding environment. This motivates a\nfunctionalization approach, where external molecules are adsorbed to the\nmaterials surface to tailor its optical properties. Here, we apply the density\nmatrix theory to investigate the potential of non-covalently functionalized\nTMDs. Considering exemplary spiropyran molecules with a strong dipole moment,\nwe predict spectral redshifts and the appearance of an additional side peak in\nthe absorption spectrum of functionalized TMDs. We show that the molecular\ncharacteristics, e.g. coverage, orientation and dipole moment, crucially\ninfluence the optical properties of TMDs, leaving a unique optical fingerprint\nin the absorption spectrum. Furthermore, we find that the molecular dipole\nmoments open a channel for coherent intervalley coupling between the\nhigh-symmetry K and K' points which may open new possibilities for\nspin-valleytronics application."
    },
    {
        "anchor": "Analytic solution for electrons and holes in graphene under\n  electromagnetic radiation: gap appearance and non-linear current effects: We find the exact solution of graphene s carriers under electromagnetic\nradiation. To obtain such solution, we combine Floquet theory with a trial\nsolution. Then the energy spectrum is obtained without using any approximation.\nUsing such results, we prove that the energy spectrum presents a gap opening\nwhich depends on de radiation frequency and electric wave intensity, whereas\nthe current shows a strongly non-linear behaviour.",
        "positive": "Spin relaxation due to the Bir-Aronov-Pikus mechanism in intrinsic and\n  $p$-type GaAs quantum wells from a fully microscopic approach: We study the electron spin relaxation in intrinsic and $p$-type (001) GaAs\nquantum wells by constructing and numerically solving the kinetic spin Bloch\nequations. All the relevant scatterings are explicitly included, especially the\nspin-flip electron-heavy hole exchange scattering which leads to the\nBir-Aronov-Pikus spin relaxation. We show that, due to the neglection of the\nnonlinear terms in the electron-heavy hole exchange scattering in the\nFermi-golden-rule approach, the spin relaxation due to the Bir-Aronov-Pikus\nmechanism is greatly exaggerated at moderately high electron density and low\ntemperature in the literature. We compare the spin relaxation time due to the\nBir-Aronov-Pikus mechanism with that due to the D'yakonov-Perel' mechanism\nwhich is also calculated from the kinetic spin Bloch equations with all the\nscatterings, especially the spin-conserving electron-electron and\nelectron-heavy hole scatterings, included. We find that, in intrinsic quantum\nwells, the effect from the Bir-Aronov-Pikus mechanism is much smaller than that\nfrom the D'yakonov-Perel' mechanism at low temperature, and it is smaller by no\nmore than one order of magnitude at high temperature. In $p$-type quantum\nwells, the spin relaxation due to the Bir-Aronov-Pikus mechanism is also much\nsmaller than the one due to the D'yakonov-Perel' mechanism at low temperature\nand becomes comparable to each other at higher temperature when the hole\ndensity and the width of the quantum well are large enough. We claim that\nunlike in the bulk samples, the Bir-Aronov-Pikus mechanism hardly dominates the\nspin relaxation in two-dimensional samples."
    },
    {
        "anchor": "Carbon nanotube array vias for interconnect applications: The material and electrical properties of the CNT single vias and array vias\ngrown by microwave plasma-enhanced chemical vapor deposition were investigated.\nThe diameters of multiwall carbon nanotubes (MWNTs) grown on the bottom\nelectrode of Ta decrease with increasing pretreatment power and substrate\ntemperature while the effects of the growth power and methane flow ratio are\ninsignificant The decrease of CNT diameters leads to the decrease of the CNT\nvia diode devices. The increase of growth power enhances the CNT graphitization\ndegree and thue the conductivity of CNT via diode devices. In the same via\nregion, the MWNT diode resistances of the array vias are lower than those of\nthe single vias. The MWNT diode resistances on the bottom electrode of titanium\nare lower than those on the bottom electrode of tantalum. It may be attributed\nto the smaller tube diameters on the bottom electrode of Ti and the work\nfunction difference between Ta and Ti films with respect to the work function\nof CNTs.",
        "positive": "Possible applications of Mo2C in the orthorhombic and hexagonal phases\n  explored via ab-initio investigations of elastic, bonding, optoelectronic and\n  thermophysical properties: Binary carbides demonstrate attractive set of physical properties that are\nsuitable for numerous and diverse applications. In the present study, we have\nexplored the structural properties, electronic structures, elastic constants,\nacoustic behaviors, phonon dispersions, optical properties, and various\nthermophysical properties of binary orthogonal and hexagonal Mo2C compounds in\ndetails via first-principles calculations using the density functional theory\n(DFT). The calculated ground state lattice parameters in both the symmetries\nare in excellent agreement with available experimental results. The calculated\nelectronic band structure, density of states, and optical properties of Mo2C in\nboth structures reveal metallic features. The orthorhombic crystal shows higher\nlevel mechanical and thermal anisotropy compared to that in the hexagonal\nphase. The elastic constants and phonon dispersion calculations show that, in\nboth structures, Mo2C is mechanically and dynamically stable. A comprehensive\nmechanical and thermophysical study shows that both phases possess high\nstructural stability, reasonably good machinability, ductile nature, high\nhardness, low compressibility, high Debye temperature and high melting\ntemperature. Moreover, the electronic energy density of states, electron\ndensity distribution, elastic properties, and Mulliken bond population analyses\nindicate that the structures under consideration consist of mixed bonding\ncharacteristics with ionic and covalent contributions. High reflectivity over\nwide spectral range makes the compound suitable as reflecting coating. Both the\nstructures are efficient absorber of ultraviolet radiation. The refractive\nindices are quite high in the infrared to visible range."
    },
    {
        "anchor": "Ionic liquid gating of SrTiO$_3$ lamellas fabricated with a focused ion\n  beam: In this work, we combine two previously-incompatible techniques for defining\nelectronic devices: shaping three-dimensional crystals by focused ion beam\n(FIB), and two-dimensional electrostatic accumulation of charge carriers. The\nprincipal challenge for this integration is nanometer-scale surface damage\ninherent to any FIB-based fabrication. We address this by using a sacrificial\nprotective layer to preserve a selected pristine surface. The test case\npresented here is accumulation of 2D carriers by ionic liquid gating at the\nsurface of a micron-scale SrTiO$_3$ lamella. Preservation of surface quality is\nreflected in superconductivity of the accumulated carriers. This technique\nopens new avenues for realizing electrostatic charge tuning in materials that\nare not available as large or exfoliatable single crystals, and for patterning\nthe geometry of the accumulated carriers.",
        "positive": "Spin-correlated exciton-polaritons in a van der Waals magnet: Strong coupling between light and elementary excitations is emerging as a\npowerful tool to engineer the properties of solid-state systems.\nSpin-correlated excitations that couple strongly to optical cavities promise\ncontrol over collective quantum phenomena such as magnetic phase transitions,\nbut their suitable electronic resonances have yet to be found. Here we report\nstrong light-matter coupling in $\\textrm{NiPS}_3$, a van der Waals\nantiferromagnet with highly correlated electronic degrees of freedom. A\npreviously unobserved class of polaritonic quasiparticles emerges from the\nstrong coupling between its spin-correlated excitons and the photons inside a\nmicrocavity. Detailed spectroscopic analysis in conjunction with a microscopic\ntheory provides unique insights into the origin and interactions of these\nexotic magnetically coupled excitations. Our work introduces van der Waals\nmagnets to the field of strong light-matter physics and provides a path towards\nthe design and control of correlated electron systems via cavity quantum\nelectrodynamics."
    },
    {
        "anchor": "Equations of state for solids at high pressures and temperatures from\n  shock-wave data: This paper deals with the analytic derivation of a complete equation of state\n(EOS) for solids from shock-wave data in the range of pressures and\ntemperatures, attained by detonation of chemical explosives. The caloric, the\nthermal and the incomplete EOS are determined as well. An equation for the\nshock temperature along the Hugoniot curve is derived also.",
        "positive": "Three-Dimensional Elastic Compatibility: Twinning in Martensites: We show how the St.Venant compatibility relations for strain in three\ndimensions lead to twinning for the cubic to tetragonal transition in\nmartensitic materials within a Ginzburg-Landau model in terms of the six\ncomponents of the symmetric strain tensor. The compatibility constraints\ngenerate an anisotropic long-range interaction in the order parameter\n(deviatoric strain) components. In contrast to two dimensions, the free energy\nis characterized by a \"landscape\" of competing metastable states. We find a\nvariety of textures, which result from the elastic frustration due to the\neffects of compatibility. Our results are also applicable to structural phase\ntransitions in improper ferroelastics such as ferroelectrics and\nmagnetoelastics, where strain acts as a secondary order parameter."
    },
    {
        "anchor": "Dynamical Jahn-Teller effect of fullerene anions: The dynamical Jahn-Teller effect of C$_{60}^{n-}$ anions ($n = $ 1-5) is\nstudied using the numerical diagonalization of the linear $p^n \\otimes 8d$\nJahn-Teller Hamiltonian with the currently established coupling parameters. It\nis found that in all anions the Jahn-Teller effect stabilizes the low-spin\nstates, resulting in the violation of Hund's rule. The energy gain due to the\nJahn-Teller dynamics is found to be comparable to the static Jahn-Teller\nstabilization. The Jahn-Teller dynamics influences the thermodynamic properties\nvia strong variation of the density of vibronic states with energy. Thus, the\nlarge vibronic entropy in the low-spin states enhances the effective spin gap\nof C$_{60}^{3-}$ quenching the spin crossover. From the calculations of the\neffective spin gap in function of the Hund's rule coupling, we found that the\nlatter should amount 40 $\\pm$ 5 meV in order to cope with the violation of\nHund's rule and to reproduce the large spin gap. With the obtained numerical\nsolutions the matrix elements of electronic operators for the low-lying\nvibronic levels and the vibronic reduction factors are calculated for all\nanions.",
        "positive": "Non-empirical Generalized Gradient Approximation Free Energy Functional\n  for Orbital-free Simulations: We report the first wholly non-empirical generalized gradient approximation,\nnon-interacting free energy functional for orbital-free density functional\ntheory and use that new functional to provide forces for finite-temperature\nmolecular dynamics simulations in the warm dense matter (WDM) regime The new\nfunctional provides good-to-excellent agreement with reference Kohn-Sham\ncalculations under WDM conditions at a minuscule fraction of the computational\ncost of corresponding orbital-based simulations."
    },
    {
        "anchor": "Lead Iodide Perovskite Light-Emitting Field-Effect Transistor: Despite the widespread use of solution-processable hybrid organic-inorganic\nperovskites in photovoltaic and light-emitting applications, determination of\ntheir intrinsic charge transport parameters has been elusive due to the\nvariability of film preparation and history-dependent device performance. Here\nwe show that screening effects associated to ionic transport can be effectively\neliminated by lowering the operating temperature of methylammonium lead iodide\nperovskite (CH3NH3PbI3) field-effect transistors (FETs). Field-effect carrier\nmobility is found to increase by almost two orders of magnitude below 200 K,\nconsistent with phonon scattering limited transport. Under balanced ambipolar\ncarrier injection, gate-dependent electroluminescence is also observed from the\ntransistor channel, with spectra revealing the tetragonal to orthorhombic phase\ntransition. This first demonstration of CH3NH3PbI3 light-emitting FETs provides\nintrinsic transport parameters to guide materials and solar cell optimization,\nand will drive the development of new electro-optic device concepts, such as\ngated light emitting diodes and lasers operating at room temperature.",
        "positive": "Magnetoelectric coupling and decoupling in multiferroic hexagonal YbFeO3\n  thin films: The coupling between ferroelectric and magnetic orders in multiferroic\nmaterials and the nature of magnetoelectric (ME) effects are enduring\nexperimental challenges. In this work, we have studied the response of\nmagnetization to ferroelectric switching in thin-film hexagonal YbFeO3, a\nprototypical improper multiferroic. The bulk ME decoupling and potential\ndomain-wall ME coupling were revealed using x-ray magnetic circular dichroism\n(XMCD) measurements with in-situ ferroelectric polarization switching. Our\nLandau theory analysis suggests that the bulk ME-coupled ferroelectric\nswitching path has a higher energy barrier than that of the ME-decoupled path;\nthis extra barrier energy is also too high to be reduced by the magneto-static\nenergy in the process of breaking single magnetic domains into multi-domains.\nIn addition, the reduction of magnetization around the ferroelectric domain\nwalls predicted by the Landau theory may induce the domain-wall ME coupling in\nwhich the magnetization is correlated with the density of ferroelectric domain\nwalls. These results provide important experimental evidence and theoretical\ninsights into the rich possibilities of ME couplings in hexagonal ferrites,\nsuch as manipulating the magnetic states by an electric field."
    },
    {
        "anchor": "Spin relaxation under identical Dresselhaus and Rashba coupling\n  strengths in GaAs quantum wells: Spin relaxation under identical Dresselhaus and Rashba coupling strengths in\nGaAs quantum wells is studied in both the traditional collinear statistics,\nwhere the energy spectra do not contain the spin-orbit coupling terms, and the\nhelix statistics, where the spin-orbit couplings are included in the energy\nspectra. We show that there is only marginal difference between the spin\nrelaxation times obtained from these two different statistics. We further show\nthat with the cubic term of the Dresselhaus spin-orbit coupling included, the\nspin relaxation time along the (1,1,0) direction becomes finite, although it is\nstill much longer than that along the other two perpendicular directions. The\nproperties of the spin relaxation along this special direction under varies\nconditions are studied in detail.",
        "positive": "Vibrational spectra of C60C8H8 and C70C8H8 in the rotor-stator and\n  polymer phases: C60-C8H8 and C70-C8H8 are prototypes of rotor-stator cocrystals. We present\ninfrared and Raman spectra of these materials and show how the rotor-stator\nnature is reflected in their vibrational properties. We measured the\nvibrational spectra of the polymer phases poly(C60C8H8) and poly(C70C8H8)\nresulting from a solid state reaction occurring on heating. Based on the\nspectra we propose a connection pattern for the fullerene in poly(C60C8H8),\nwhere the symmetry of the C60 is D2h. On illuminating the C60-C8H8 cocrystal\nwith green or blue light a photochemical reaction was observed leading to a\nsimilar product to that of the thermal polymerization."
    },
    {
        "anchor": "p-Type semiconducting properties in lithium-doped MgO single crystals: The phenomenally large enhancement in conductivity observed when Li-doped MgO\ncrystals are oxidized at elevated temperatures was investigated by dc and ac\nelectrical measurements in the temperature interval 250-673 K. The\nconcentration of ([Li]^{0}) centers (Li^{+} ions each with a trapped hole)\nresulting from oxidation was monitored by optical absorption measurements.\n  Both dc and ac experiments provide consistent values for the bulk resistance.\nThe electricalconductivity of oxidized MgO:Li crystals increases linearly with\nthe concentration of ([Li]^{0}) centers. The conductivity is thermally\nactivated with an activation energy of (0.70 +/- 0.01) eV, which is independent\nof the ([Li]^{0}) content. The \\textit{standard semiconducting} mechanism\nsatisfactorily explains these results. Free holes are the main contribution to\nband conduction as they are trapped at or released from the ([Li]^{0})-acceptor\ncenters.\n  In as-grown MgO:Li crystals, electrical current increases dramatically with\ntime due to the formation of ([Li]^{0}) centers. The activation energy values\nbetween 1.3 and 0.7 eV are likely a combination of the activation energy for\nthe creation of ([Li]^{0}) centers and the activation energy of ionization of\nthese centers. Destruction of ([Li]^{0}) centers can be induced in oxidized\ncrystals by application of an electric field due to Joule heating up to\ntemperatures at which ([Li]^{0}) centers are not stable.",
        "positive": "Pressure Engineering of the Dirac Fermions in Quasi-One-Dimensional\n  Tl$_2$Mo$_6$Se$_6$: Topological band dispersions other than the standard Dirac or Weyl fermions\nhave garnered the increasing interest in materials science. Among them, the\ncubic Dirac fermions were recently proposed in the family of\nquasi-one-dimensional conductors A$_2$Mo$_6$X$_6$ (A= Na, K, In, Tl; X= S, Se,\nTe), where the band crossing is characterized by a linear dispersion in one\n$k$-space direction but the cubic dispersion in the plane perpendicular to it.\nIt is not yet clear, however, how the external perturbations can alter these\nnontrivial carriers and ultimately induce a new distinct quantum phase. Here we\nstudy the evolution of Dirac fermions, in particular the cubic Dirac crossing,\nunder external pressure in the representative quasi-one-dimensional\nTl$_2$Mo$_6$Se$_6$ via the first-principles calculations. Specifically, it is\nfound that the topological properties, including the bulk Dirac crossings and\nthe topological surface states, change progressively under pressure up to 50\nGPa where it undergoes a structural transition from the hexagonal phase to\nbody-centered tetragonal phase. Above 50 GPa, the system is more likely to be\ntopologically trivial. Further, we also investigate its phonon spectra, which\nreveals a gradual depletion of the negative phonon modes with pressure,\nconsistent with the more three-dimensional Fermi surface in the high-pressure\nphase. Our work may provide a useful guideline for further experimental search\nand the band engineering of the topologically nontrivial fermions in this\nintriguing state of matter."
    },
    {
        "anchor": "Modelling of Nonlocal Effects in Electromechanical Nano-Switches: Dielectric nano-swithes made of the materials that exhibit piezoelectric\nand/or flexoelectric properties with significant electro-mechanical coupling\nare considered. In this case, a nonuniform strain field may locally break\ninversion symmetry and induce polarization even in nonpiezoelectrics. At\nreducing dimensions to the nanoscale, the flexoelectric effect demonstrates the\nnonlocality of the dielectric materials and plays more significant role than\npiezoelectric effect. The flexoelectric effect is included into consideration\nvia additional term coupling strain gradient and polarization in the electric\nenthalpy density. The equations of motion of the improved Euler-Bernoulli and\nTimoshenko beam models, and 2-D plate theory have been obtained.",
        "positive": "Slater-Pauling behavior in half-metallic magnets: We review the appearance of Slater-Pauling rules in half-metallic magnets.\nThese rules have been derived using ab-initio electronic structure calculations\nand directly connect the electronic properties (existence of minority-spin\nenergy gap) to the magnetic properties (total spin magnetic moment) in these\ncompounds. Their exact formulation depends on the half-metallic family under\nstudy and they can be easily derived if the hybridization of the orbitals at\nvarious sites is taken into account."
    },
    {
        "anchor": "Buckling of graphene/MoS$_2$ van der Waals heterostructures: the misfit\n  strain effect: Van der Waals heterostructures are constructed by stacking different atomic\nlayers and can inherit many novel electronic and optical properties from the\nconstituting atomic layers. Mechanical stability is of key importance for the\nhigh performance of nano devices based on the van der Waals heterostructure. In\nparticular, buckling instability is a critical mechanical issue for the\nheterostructure due to its two-dimensional nature. Using graphene/MoS$_2$\nheterostructure as an example, the present work demonstrates the relationship\nbetween the buckling instability and the inevitable misfit strain in the\nheterostructure by molecular dynamics simulations. The misfit strain has rather\ndifferent effects on the buckling phenomenon depending on the magnitude of the\nmisfit strain.\n  (1) For negative misfit strain, the buckling stability of the heterostructure\nis reduced by the misfit strain. It is because the graphene layer, which\ninitiates the buckling process in the heterostructure of negative misfit\nstrain, is pre-compressed by the misfit strain that accelerates the buckling of\nthe graphene layer.\n  (2) For small positive misfit strain, the buckling stability for the\ngraphene/MoS$_2$ heterostructure is elevated. The underlying mechanism is that\nthe graphene layer initiates the buckling process of the heterostructure and is\npre-stretched by the small positive misfit strain, which decelerates the\nbuckling of the graphene layer.\n  (3) For large positive misfit strain, the graphene layer is pre-stretched\nwhile the MoS$_2$ layer is considerably pre-compressed, so the buckling of the\nheterostructure is initiated by the MoS$_2$ layer. As a consequence, the\nbuckling stability of the graphene/MoS$_2$ heterostructure is reduced by the\nincrease of large positive misfit strain. These findings shall be valuable for\nunderstanding mechanical properties of van der Waals heterostructures.",
        "positive": "Nucleation and cap formation on symmetric metal nanocatalysts: A first\n  step towards chirality-controlled single-walled carbon nanotube growth: Symmetric minima of surface potential energy of a nanocatalyst act as\nnucleation sites for chirally selective initial growth of single walled carbon\ntubes at low temperatures. The nucleation sites are sites of maximum\ncoordination number of the adsorbed carbon. We show this using the five fold\nsymmetry of a pentagonal pyramid of an icosahedron. Initial zigzag structure\nfrom nucleation sites results in formation of hexagons and pentagons that\nresult in anomalous cap formation. Possible cap lift off mechanism is\ndiscussed."
    },
    {
        "anchor": "Giant magnetoresistance and extraordinary magnetoresistance in\n  inhomogeneous semiconducting DyNiBi: The semiconducting half-Heulser compound DyNiBi shows a negative giant\nmagnetoresistance (GMR) below 200 K. Except for a weak deviation, this\nmagnetoresistance scales roughly with the square of the magnetization in the\nparamagnetic state, and is related to the metal-insulator transition. At low\ntemperature, a positive magnetoresistance is found, which can be suppressed by\nhigh fields. The magnitude of the positive magnetoresistance changes slightly\nwith the amount of impurity phase.",
        "positive": "Calculation and properties of trap structural functions for various\n  spatially correlated systems: Thermoluminescence (TL) kinetics in spatially inhomogeneous systems can be\nstudied by various Monte Carlo algorithms. Recently, a new analytical approach\nwas suggested for the isolated cluster model. The theory is based on the\nconcept of trap structural functions (TSFs). TSFs depend solely on topological\nproperties of solids. Therefore, knowing TSFs for traps and recombination\ncentres it is possible to calculate TL for various parameters, e.g. different\nheating schemes and different energy configurations. This paper presents some\nproperties and methods of calculation of TSFs. Structural character of TSFs is\nverified numerically. It is shown that for simple cluster systems it is\npossible to calculate the functions analytically."
    },
    {
        "anchor": "Nonradiative DKR processes: revisiting the theory. II.\n  Electron-vibrational mode coupling: We summarize a few proposals for mixing F center states through the mediation\nof an appropriate symmetry-breaking vibrational mode. Electron-mode coupling\nenergies odd-order in the mode coordinates are characteristic of the\npseudo-Jahn-Teller mixing of nearly-degenerate opposite-parity electronic\nstates mediated by an odd-parity vibrational mode. Coupling energies even order\nin the vibrational coordinates lead to a pseudo-Renner mixing of even parity\nnearly-degenerate states or to dynamic-Renner mixing of degenerate states of\nwhatever symmetry. Both Renner mixing energies add up to widen the crossover\nsplitting of the adiabatic energies thereby enhancing the nonradiative\ndeexcitation rate.",
        "positive": "Structural dynamics in hybrid halide perovskites: Bulk Rashba splitting,\n  spin texture, and carrier localization: The extended carrier lifetime in hybrid halide perovskites was attributed to\na quasi-indirect band gap that arises due to Rashba splitting in both\nconduction and valence band edges. In this paper, we present results for an\neffective relativistic band structure of (CH3NH3)PbI3 with the focus on the\ndispersion of electronic states near the band edges of (CH3NH3)PbI3 affected by\nthermal structural fluctuations. We establish a relation between the magnitude\nof Rashba splitting and a deviation of Pb-atom from its centrosymmetric site\nposition in the PbI6 octahedron. For the splitting energy to reach the thermal\nenergy kT~26 meV (room temperature), the displacement should be of the order\n0.3 Ang, which is far above the static displacements of Pb-atoms in the\ntetragonal phase of (CH3NH3)PbI3. The significant dynamic enhancement of the\nRashba splitting observed at earlier simulation times (less than 2 ps) later\nweakens and becomes less than the thermal energy despite the average\ndisplacement of Pb-atoms remaining large (0.37 Ang). It is randomization of\nPb-displacement vectors and associated cancelation of the net effective\nmagnetic field acting on electrons at the conduction band edge is responsible\nfor reduction of the Rashba splitting. The lattice dynamics also leads to\ndeterioration of Bloch character for states in the valence band leading to\nsubsequent localization of holes, which affects bipolar mobility of charge\ncarriers in (CH3NH3)PbI3. These results call into question the quasi-indirect\nband gap as a reason for the long carrier lifetime observed in (CH3NH3)PbI3 at\nroom temperature. An alternative mechanism involves dynamic localization of\nholes and their reduced overlap with electrons in reciprocal space."
    },
    {
        "anchor": "Data-driven studies of magnetic two-dimensional materials: We use a data-driven approach to study the magnetic and thermodynamic\nproperties of van der Waals (vdW) layered materials. We investigate monolayers\nof the form A$_2$B$_2$X$_6$, based on the known material Cr$_2$Ge$_2$Te$_6$,\nusing density functional theory (DFT) calculations and machine learning methods\nto determine their magnetic properties, such as magnetic order and magnetic\nmoment. We also examine formation energies and use them as a proxy for chemical\nstability. We show that machine learning tools, combined with DFT calculations,\ncan provide a computationally efficient means to predict properties of such\ntwo-dimensional (2D) magnetic materials. Our data analytics approach provides\ninsights into the microscopic origins of magnetic ordering in these systems.\nFor instance, we find that the X site strongly affects the magnetic coupling\nbetween neighboring A sites, which drives the magnetic ordering. Our approach\nopens new ways for rapid discovery of chemically stable vdW materials that\nexhibit magnetic behavior.",
        "positive": "On the limits of surface fractal behaviour in silica. A virtual\n  adsorbates simulation: A computer simulation technique, suited to replicate real adsorption\nexperiments, was applied to pure simulated silica in order to gain insight into\nthe fractal regime of its surface. The previously reported experimental fractal\ndimension was closely approached and the hitherto uncharted lower limit of\nfractal surface behaviour is reported herein."
    },
    {
        "anchor": "Ultrafast Hole-Spin Dynamics in Optically Excited Bulk GaA: We present experimental and theoretical results on hole-spin dynamics in bulk\nGaAs after ultrafast optical excitation. The experimental differential\ntransmission are compared with a dynamical calculation of the momentum-resolved\nhole distributions, which includes the carrier-carrier, carrier-phonon and\ncarrier-impurity interaction at the level of Boltzmann scattering integrals. We\nobtain good agreement with the experimentally determined hole-spin relaxation\ntimes, but point out that depending on how the spin-polarization dynamics is\nextracted, deviations from an exponential decay at short times occur. We also\nstudy theoretically the behavior of the spin-relaxation for heavily p-doped\nGaAs at low temperatures.",
        "positive": "Tuning of thermoelectric properties with changing Se content in Sb2Te3: Polycrystalline Sb 2 Te 3-x Se x (0.0 < x < 1.0) samples were synthesized by\nthe solid state reaction method. The structural analysis showed that up to the\nmaximal concentration of Se, the samples possess the Rhombohedral crystal\nsymmetry (space group R 3 m ). Increase of Se content increases the resistivity\nof the samples. Variation of phonon frequencies, observed from Raman\nspectroscopic study, depict anomalous behaviour around x = 0.2. The sample Sb 2\nTe 2.8 Se 0.2 also shows maximum Seebeck coefficient, carrier concentration and\nthermoelectric power factor. Nature of scattering mechanism controlling the\nthermopower data has been explored. The thermoelectric properties of the\nsynthesized materials have been analyzed theoretically in the frame of\nBoltzmann equation approach."
    },
    {
        "anchor": "Contrast mechanisms in secondary electron e-beam induced current\n  (SEEBIC) imaging: Over the last few years, a new mode for imaging in the scanning transmission\nelectron microscope (STEM) has gained attention as it permits the direct\nvisualization of sample conductivity and electrical connectivity. When the\nelectron beam (e-beam) is focused on the sample in the STEM, secondary\nelectrons (SEs) are generated. If the sample is conductive and electrically\nconnected to an amplifier, the SE current can be measured as a function of the\ne-beam position. This scenario is similar to the better-known scanning electron\nmicroscopy (SEM)-based technique, electron beam induced current (EBIC) imaging\nexcept the signal in STEM is generated by the emission of SEs, hence the name\nSEEBIC, and in this case the current flows in the opposite direction. Here, we\nprovide a brief review of recent work in this area, examine the various\ncontrast generation mechanisms associated with SEEBIC, and illustrate its use\nfor the characterization of graphene nanoribbon devices.",
        "positive": "Observation of Weyl nodes and Fermi arcs in TaP: A Weyl semimetal possesses spin-polarized band-crossings, called Weyl nodes,\nconnected by topological surface arcs. The low-energy excitations near the\ncrossing points behave the same as massless Weyl fermions, leading to exotic\nproperties like chiral anomaly. To have the transport properties dominated by\nWeyl fermions, Weyl nodes need to locate nearly at the chemical potential and\nenclosed by pairs of individual Fermi surfaces with nonzero Fermi Chern\nnumbers. Combining angle-resolved photoemission spectroscopy and\nfirst-principles calculation, here we show that TaP is a Weyl semimetal with\nonly single type of Weyl fermions, topologically distinguished from TaAs where\ntwo types of Weyl fermions contribute to the low-energy physical properties.\nThe simple Weyl fermions in TaP are not only of fundamental interests but also\nof great potential for future applications. Fermi arcs on the Ta-terminated\nsurface are observed, which appear in a different pattern from that on the\nAs-termination in TaAs and NbAs."
    },
    {
        "anchor": "Magnetization, specific heat, and thermal conductivity of hexagonal\n  ErMnO$_3$ single crystals: We report a study of magnetism and magnetic transitions of hexagonal\nErMnO$_3$ single crystals by magnetization, specific heat and heat transport\nmeasurements. Magnetization data show that the $c$-axis magnetic field induces\nthree magnetic transitions at 0.8, 12 and 28 T. The specific heat shows a peak\nat 2.2 K, which is due to a magnetic transition of Er$^{3+}$ moments. For\nlow-$T$ thermal conductivity ($\\kappa$), a clear dip-like feature appears in\n$\\kappa(H)$ isotherm at 1--1.25 T for $H \\parallel ab$; while in the case of $H\n\\parallel c$, a step-like increase is observed at 0.5--0.8 T. The transition\nfields in $\\kappa(H)$ are in good agreement with those obtained from\nmagnetization, and the anomaly of $\\kappa$ can be understood by a spin-phonon\nscattering scenario. The natures of magnetic structures and corresponding\nfield-induced transitions at low temperatures are discussed.",
        "positive": "Electron Transport Through Ag-Silicene-Ag Junctions: For several years the electronic structure properties of the novel\ntwo-dimensional system silicene have been studied extensively. Electron\ntransport across metal-silicence junctions, however, remains relatively\nunexplored. To address this issue, we developed and implemented a theoretical\nframework that utilizes the tight-binding Fisher-Lee relation to span\nnon-equilibrium Green's function (NEGF) techniques, the scattering method, and\nsemiclassical Boltzmann transport theory. Within this hybrid quantum-classical,\ntwo-scale framework, we calculated transmission and reflection coefficients of\nmonolayer and bilayer Ag-silicene-Ag junctions using the NEGF method in\nconjunction with density functional theory; derived and calculated the group\nvelocities; and computed resistance using the semi-classical Boltzmann\nequation. We found that resistances of these junctions are $\\sim${}$ 0.08 \\fom$\nfor monolayer silicene junctions and $\\sim${}$ 0.3 \\fom$ for bilayer ones,\nfactors of $\\sim$8 and $\\sim$2, respectively, smaller than Sharvin resistances\nestimated via the Landauer formalism."
    },
    {
        "anchor": "Magnetization reversal and domain structures in perpendicular synthetic\n  antiferromagnets prepared on rigid and flexible substrates: Ferromagnetic (FM) layers separated by nonmagnetic metallic spacer layers can\nexhibit Ruderman Kittel Kasuya Yosida (RKKY) coupling which may lead to a\nstable synthetic antiferromagnetic (SAF) phase. In this article we study\nmagnetization reversal in [Co/Pt] layers by varying the number of bilayer\nstacks (Pt/Co) as well as thickness of Ir space layer tIr on rigid Si(100) and\nflexible polyimide substrates. The samples with tIr = 1.0 nm shows a FM\ncoupling whereas samples with tIr = 1.5 nm shows an AFM coupling between the FM\nlayers. At tIr = 2.0 nm, it shows a bow-tie shaped hysteresis loop indicating a\ncanting of magnetization at the reversal. Higher anisotropy energy as compared\nto the interlayer exchange coupling (IEC) energy is an indication of the\nsmaller relative angle between the magnetization of lower and upper FM layers.\nWe have also demonstrated the strain induced modification of IEC as well as\nmagnetization reversal phenomena. The IEC shows a slight decrease upon\napplication of compressive strain and increase upon application of tensile\nstrain which indicates the potential of SAFs in flexible spintronics.",
        "positive": "Observation of magnetism in Au thin films: Direct magnetization measurements of thin gold films are presented. These\nmeasurements integrate the signal from the thin film under study and the\nmagnetic contribution of the film's interface with the substrate. The\ndiamagnetic contribution to the signal from the bulk substrate is of the same\norder as the noise level. we find that thin gold films can exhibit positive\nmagnetization. The character of their magnetic behavior is strongly substrate\ndependent."
    },
    {
        "anchor": "Colossal switchable photocurrents in topological Janus transition metal\n  dichalcogenides: Nonlinear optical properties, such as bulk photovoltaic effects, possess\ngreat potential in energy harvesting, photodetection, rectification, etc. To\nenable efficient light-current conversion, materials with strong\nphoto-responsivity are highly desirable. In this work, we predict that\nmonolayer Janus transition metal dichalcogenides (JTMDs) in the 1T' phase\npossess colossal nonlinear photoconductivity owing to their topological band\nmixing, strong inversion symmetry breaking, and small electronic bandgap. 1T'\nJTMDs have inverted bandgaps on the order of 10 meV and are exceptionally\nresponsive to light in the terahertz (THz) range. By first-principles\ncalculations, we reveal that 1T' JTMDs possess shift current (SC) conductivity\nas large as $2300 ~\\rm nm \\cdot \\mu A / V^2$, equivalent to a\nphoto-responsivity of $2800 ~\\rm mA/W$. The circular current (CC) conductivity\nof 1T' JTMDs is as large as $10^4~ \\rm nm \\cdot \\mu A / V^2$. These remarkable\nphoto-responsivities indicate that the 1T' JTMDs can serve as efficient\nphotodetectors in the THz range. We also find that external stimuli such as the\nin-plane strain and out-of-plane electric field can induce topological phase\ntransitions in 1T' JTMDs and that the SC can abruptly flip their directions.\nThe abrupt change of the nonlinear photocurrent can be used to characterize the\ntopological transition and has potential applications in 2D optomechanics and\nnonlinear optoelectronics.",
        "positive": "Fast polymerization at low temperature of an infrared radiation cured\n  epoxy-amine adhesive: In the industry, the cure time of two-component adhesives is very important\nfor a cost-effective manufacturing. Too fast, it does not favor the application\nof the product and the control of bonded joints. Too slow, it leads to long\nprocess times and too high process costs. The best compromises are\ntwo-component adhesives that cure slowly at room temperature and can reach full\npolymerization in minutes, on demand. In this paper, the curing behavior of a\nmodel poly-epoxide adhesive (a stoichiometric mixture of a pure epoxy and\namine) polymerized with infrared radiation will be studied. The kinetic\nfollow-up of this polymerization will be carried out by thermal analysis\n(determination of the residual heat peak by Differential Scanning\nCalorimetry-DSC). This study paves the way to a cold and universal\ncure-on-demand process, which means achieved in few minutes at low temperature\nwithout any initiators, catalysts or accelerators. Basically, infrared curing\ncan be possible thanks to an increase in temperature (called thermal effect).\nBut it has been shown that a \"non-thermal effect\" could also be involved in\naccelerating kinetics with infrared. This increase due to a non-thermal effect,\nsuggested as a function of the infrared radiative flux, has been shown to be\npossible thanks to the absorption of infrared radiation, leading to a reduction\nin the energy barrier of the primary epoxy/amine reaction."
    },
    {
        "anchor": "A General Principle: \u03c0-Conjugated Confinement Maximizes Band Gap of\n  DUV NLO Materials: Current nonlinear optical materials face a conventional limitation on the\ntradeoff between band gap and birefringence, especially in the deep UV spectral\nregion. To circumvent such a dilemma, we propose a general principle, a\n{\\pi}-conjugated confinement, to partially decouple the inter group\n{\\pi}-conjugated interactions with the separation of a non-{\\pi}-conjugated\ngroup so as to maximize the band gap in comparison with those of simple\n{\\pi}-conjugated salts, such as borates, carbonates. Meanwhile, to maintain a\nlarge optical anisotropy. We uncover that the {\\pi}-conjugated confinement is a\nshared structural feature for all the known DUV NLO materials with favorable\nproperties (45 compounds), and thus, it provides an essential design criterion.\nGuided by this principle, the carbonophosphate is predicted theoretically for\nthe first time as a promising DUV candidate system, Sr3Y[PO4][CO3]3 and\nNa3X[PO4][CO3] (X = Ba, Sr, Ca, Mg) exhibit an enhanced birefringence that is\n3-24 times larger than that of the simple phosphate, as well as an increased\nband gap that is 0.2-1.7 eV wider than that of the simple carbonate.\nEspecially, the shortest SHG output of Sr3Y[PO4][CO3]3 is at {\\lambda}PM = 181\nnm, being the shortest one among phosphates to date.",
        "positive": "Hidden interplay of current-induced spin and orbital torques in bulk\n  Fe$_3$GeTe$_2$: Low crystal symmetry of magnetic van der Waals materials naturally promotes\nspin-orbital complexity unachievable in common magnetic materials used for\nspin-orbit torque switching. Here, using first-principles methods, we\ndemonstrate that an interplay of spin and orbital degrees of freedom has a\nprofound impact on spin-orbit torques in a prototype van der Waals ferromagnet:\nFe$_3$GeTe$_2$ (FGT). While we show that bulk FGT hosts strong \"hidden\"\ncurrent-induced torques harvested by each of its layers, we uncover that their\norigin alternates between the conventional spin flux torque and the so-called\norbital torque as the magnetization direction is varied. A drastic difference\nin the behavior of the two types of torques results in a non-trivial evolution\nof switching properties with doping. Our findings promote the design of\nnon-equilibrium orbital properties as the guiding mechanism for crafting the\nproperties of spin-orbit torques in layered van der Waals materials."
    },
    {
        "anchor": "Bulk motion of granular matter in an agitated cylindrical bed: Experimental results are reported for the bulk motion induced in a bed of\ngranular matter contained in a cylindrical pan with a flat bottom subjected to\nsimultaneous vertical and horizontal vibrations. The motion in space of the\nmoving pan is quantified. A number of distinct bulk dynamical modes are\nobserved in which the particle bed adopts different shapes and motions. At the\nlowest pan excitation frequency $\\omega$, the bed forms a ``heap,'' and rotates\nabout the cylinder axis. As $\\omega$ is increased, a more complex ``toroidal''\nmode appears in which the bed takes the shape of a torus; in this mode,\ncirculation occurs both about the cylinder axis, and also radially, with\nparticles moving from the outer edge of the pan to the centre on the top\nsurface of the bed, and back to the outer edge along the pan bottom. At the\nhighest $\\omega$, surface modulations (``surface waves'' and ``sectors'') of\nthe toroidal mode occur. The origin of this family of behavior in terms of the\npan motion is discussed.",
        "positive": "Topological Kagome magnet Co3Sn2S2 thin flakes with high electron\n  mobility and large anomalous Hall effect: Magnetic Weyl semimetals attract considerable interest not only for their\ntopological quantum phenomena but also as an emerging materials class for\nrealizing quantum anomalous Hall effect in the two-dimensional limit. A\nshandite compound Co3Sn2S2 with layered Kagome-lattices is one such material,\nwhere vigorous efforts have been devoted to synthesize the two-dimensional\ncrystal. Here we report a synthesis of Co3Sn2S2 thin flakes with a thickness of\n250 nm by chemical vapor transport method. We find that this facile bottom-up\napproach allows the formation of large-sized Co3Sn2S2 thin flakes of\nhigh-quality, where we identify the largest electron mobility (~2,600\ncm2V-1s-1) among magnetic topological semimetals, as well as the large\nanomalous Hall conductivity (~1,400 {\\Omega}-1cm-1) and anomalous Hall angle\n(~32 %) arising from the Berry curvature. Our study provides a viable platform\nfor studying high-quality thin flakes of magnetic Weyl semimetal and stimulate\nfurther research on unexplored topological phenomena in the two-dimensional\nlimit."
    },
    {
        "anchor": "Composition induced diffused to relaxor ferroelectric phase transition\n  in lead-free (1-x)(Li0.12Na0.88)NbO3-xBaTiO3 (0 to x to 0.40) ferroelectric\n  ceramics: (1-x)Li0.12Na0.88NbO3-xBaTiO3 (0 to x to 0.40) ferroelectric ceramics were\nprepared using conventional ceramics route and their phase transitional\nbehavior is investigated by using dielectric spectroscopy. The\ntemperature-dependent dielectric permittivity epsilon'(T) shows a diffused\nferroelectric-paraelectric transition for all compositions. An acceptable and\ncompetent characterizing parameter (D) of diffused phase transition (DPT),\ndefined by Uchino et al. [J Am Ceram Soc 2010;93:4011], was measured and\nvalidated. Interestingly, a crossover from diffused ferroelectric phase\ntransition (FE-DPT) to relaxor ferroelectric (RFE) transition is found for the\ncomposition x greater than equal to 0.225. The FE-DPT is characterized by a\nfrequency-independent temperature of dielectric maxima (Tm), while a RFE is\nfound to have frequency-dependent Tm satisfying Vogel-Fulcher relation. The\ncomposition induced crossover is attributed to the dynamics of different PNR\nsize and relaxation times that varies with different BaTiO3 content (x) leading\nto the appearance of a FE-DPT or RFE.",
        "positive": "Quenched magnetic moment in Mn-doped amorphous Si\n  (\\textit{a}-Mn$_{x}$Si$_{1-x}$) across the metal-insulator transition: The magnetic and electrical transport properties of Mn-doped amorphous\nsilicon (\\textit{a-}Mn$_{x}$Si$_{1-x}$) thin films have been measured. The\nmagnetic susceptibility obeys the Curie-Weiss law for a wide range of $x$\n(0.005-0.175) and the saturation moment is small. While all Mn atoms contribute\nto the electrical transport, only a small fraction (interstitial Mn$^{2+}$\nstates with $J$=$S$=5/2) contribute to the magnetization. The majority of the\nMn atoms do not possess any magnetic moment, contrary to what is predicted by\nthe Ludwig-Woodbury model for Mn in crystalline silicon. Unlike\n\\textit{a-}Gd$_{x}$Si$_{1-x}$ films which have an enormous \\textit{negative}\nmagnetoresistance, \\textit{a-}Mn$_{x}$Si$_{1-x}$ films have only a small\n\\textit{positive} magnetoresistance, which can be understood by this quenching\nof the Mn moment."
    },
    {
        "anchor": "Comparative High Pressure Raman Study of Boron Nitride Nanotubes and\n  Hexagonal Boron Nitride: High pressure Raman experiments on Boron Nitride multi-walled nanotubes show\nthat the intensity of the vibrational mode at ~ 1367 cm-1 vanishes at ~ 12 GPa\nand it does not recover under decompression. In comparison, the high pressure\nRaman experiments on hexagonal Boron Nitride show a clear signature of a phase\ntransition from hexagonal to wurtzite at ~ 13 GPa which is reversible on\ndecompression. These results are contrasted with the pressure behavior of\ncarbon nanotubes and graphite.",
        "positive": "Funneling and spin-orbit coupling in transition-metal dichalcogenide\n  nanotubes and wrinkles: Strain engineering provides a powerful means to tune the properties of\ntwo-dimensional materials. Accordingly, numerous studies have investigated the\neffect of bi- and uniaxial strain. Yet, the strain fields in many systems such\nas nanotubes and nanoscale wrinkles are intrinsically inhomogeneous and the\nconsequences of this symmetry breaking are much less studied. Understanding how\nthis affects the electronic properties is crucial especially since wrinkling is\na powerful method to apply strain to two-dimensional materials in a controlled\nmanner. In this paper, we employ density functional theory to understand the\ncorrelation between the atomic and the electronic structure in nanoscale\nwrinkles and nanotubes of the prototypical transition metal dichalcogenide\n$\\mathrm{WSe}_2$. Our research shows that the symmetry breaking in these\nstructures leads to strong Rashba-like splitting of the bands at the $\\Gamma$\npoint and they thus may be utilized in future tunable spintronic devices. The\ninhomogeneous strain reduces the band gap and leads to a localization of the\nband edges in the highest-curvature region, thus funneling excitons there.\nMoreover, we show how wrinkles can be modeled as nanotubes with the same\ncurvature and when this comparison breaks down and further inhomogenities have\nto be taken into account."
    },
    {
        "anchor": "A recommendation engine for suggesting unexpected thermoelectric\n  chemistries: The experimental search for new thermoelectric materials remains largely\nconfined to a limited set of successful chemical and structural families, such\nas chalcogenides, skutterudites, and Zintl phases. In principle, computational\ntools such as density functional theory (DFT) offer the possibility of\nrationally guiding experimental synthesis efforts toward very different\nchemistries. However, in practice, predicting thermoelectric properties from\nfirst principles remains a challenging endeavor, and experimental researchers\ngenerally do not directly use computation to drive their own synthesis efforts.\nTo bridge this practical gap between experimental needs and computational\ntools, we report an open machine learning-based recommendation engine\n(http://thermoelectrics.citrination.com) for materials researchers that\nsuggests promising new thermoelectric compositions, and evaluates the\nfeasibility of user-designed compounds. We show that this engine can identify\ninteresting chemistries very different from known thermoelectrics.\nSpecifically, we describe the experimental characterization of one example set\nof compounds derived from our engine, RE12Co5Bi (RE = Gd, Er), which exhibits\nsurprising thermoelectric performance given its unprecedentedly high loading\nwith metallic d and f block elements, and warrants further investigation as a\nnew thermoelectric material platform.",
        "positive": "Yield Strength-Plasticity Trade-Off and Uncertainty Quantification for\n  Machine-learning-based Design of Refractory High-Entropy Alloys: Development of process-structure-property relationships in materials science\nis an important and challenging frontier which promises improved materials and\nreduced time and cost in production. Refractory high entropy alloys (RHEAs) are\na class of materials that are capable of excellent hightemperature properties.\nHowever, due to their multi-component nature, RHEAs have a vast composition\nspace which presents challenges for traditional experimental exploration. Here,\nquantitative models of compressive yield strength and room-temperature\nplasticity are developed through a deep learning approach. Uncertainty\nquantification is performed through a variety of statistical validation\ntechniques. Model predictions are experimentally validated through collection\nof recent literature and the synthesis and experimental characterization of two\nnew, unreported RHEAs: AlMoTaTiZr and Al0.239Mo0.123Ta0.095Ti0.342Zr0.201.\nFinally, through the application of model interpretability, features having the\ngreatest impact on both the mechanical property and uncertainty of the deep\nlearning models are revealed, and shown to agree well with current physics and\nmaterials science theory."
    },
    {
        "anchor": "Vortex motion in chilarity-controlled pair of magnetic disks: We investigate the influence of the vortex chirality on the magnetization\nprocesses of a magnetostatically coupled pair of magnetic disks. The magnetic\nvortices with opposite chiralities are realized by introducing asymmetry into\nthe disks. The motion of the paired vortices are studied by measuring the\nmagnetoresistance with lock-in resistance bridge technique. The vortex\nannihilation process is found to depend on the moving directions of the\nmagnetic vorticies. The experimental results are well reproduced by the\nmicromagnetic simulation.",
        "positive": "Electronic Structure of Strongly Correlated Systems Emerging from\n  Combining Path-Integral Renormalization Group with Density Functional\n  Approach: A new scheme of first-principles computation for strongly correlated electron\nsystems is proposed. This scheme starts from the local-density approximation\n(LDA) at high-energy band structure, while the low-energy effective Hamiltonian\nis constructed by a downfolding procedure using combinations of the constrained\nLDA and the GW method. Thus obtained low-energy Hamiltonian is solved by the\npath-integral renormalization-group method, where spatial and dynamical\nfluctuations are fully considered. An application to Sr$_2$VO$_4$ shows that\nthe scheme is powerful in agreement with experimental results. It further\npredicts a nontrivial orbital-stripe order."
    },
    {
        "anchor": "Point defects in epitaxial silicene on Ag(111) surface: Silicene, a counterpart of graphene, has achieved rapid development due to\nits exotic electronic properties and excellent compatibility with the mature\nsilicon-based semiconductor technology. Its low room-temperature mobility of\nabout 100 cm2V-1s-1, however, inhibits device applications such as in\nfield-effect transistors. Generally, defects and grain boundaries would act as\nscattering centers and thus reduce the carrier mobility. In this paper, the\nmorphologies of various point defects in epitaxial silicene on Ag(111) surfaces\nhave been systematically investigated using first-principles calculations\ncombined with experimental scanning tunneling microscope (STM) observations.\nThe STM signatures for various defects in epitaxial silicene on Ag(111) surface\nare identified. In particular, the formation energies of point defects in\nAg(111)-supported silicene sheets show an interesting dependence on the\nsuperstructures, which, in turn, may have implications for controlling the\ndefect density during the synthesis of silicene. Through estimating the\nconcentrations of various point defects in different silicene superstructures,\nthe mystery of the defective appearance of v13*v13 silicene in experiments is\nrevealed, and 4*4 silicene sheet is thought to be the most suitable structure\nfor future device applications.",
        "positive": "Prediction of Band Structure of $Bi_2Te_3$-related Binary and Ternary\n  Thermoelectric Materials: Density functional calculations have performed to study the band structures\nof $Bi_2Te_3$-related binary ($Bi_2Te_3$, $Sb_2Te_3$, $Bi_2Se_3$, and\n$Sb_2Se_3$) and $Sb$/$Se$ doped ternary compounds [$(Bi_{1-x}Sb_x)_2Te_3$ and\n$Bi_2(Te_{1-y}Se_y)_3$]. It is found that the band gap can be increased by $Sb$\ndoping and it is monotonically increased by $Se$ doping. In ternary compounds,\nthe change of the conduction band structure is more significant, as compared to\nthe change of valence band. The band degeneracy of valence band maximum is\nmaintained to be 6 in binaries and ternaries. However, as going from $Bi_2Te_3$\nto $Sb_2Te_3$ ($Bi_2Se_3$), the degeneracy of conduction band minimum is\nreduced from 6 to 2(1). Based on the results of band structures, we suggest the\nsuitable stoichiometries of ternary compounds for high thermoelectric\nperformance."
    },
    {
        "anchor": "Prediction and understanding of barocaloric effects in orientationally\n  disordered materials from molecular dynamics simulations: Due to its high energy efficiency and environmental friendliness, solid-state\ncooling based on the barocaloric (BC) effect represents a promising alternative\nto traditional refrigeration technologies relying on greenhouse gases. Plastic\ncrystals displaying orientational order-disorder solid-solid phase transitions\nhave emerged among the most gifted materials on which to realize the full\npotential of BC solid-state cooling. However, a comprehensive understanding of\nthe atomistic mechanisms on which order-disorder BC effects are sustained is\nstill missing, and rigorous and systematic methods for quantitatively\nevaluating and anticipating them have not been yet established. Here, we\npresent a computational approach for the assessment and prediction of BC\neffects in orientationally disordered materials that relies on atomistic\nmolecular dynamics simulations and emulates quasi-direct calorimetric BC\nmeasurements. Remarkably, the proposed computational approach allows for a\nprecise determination of the partial contributions to the total entropy\nstemming from the vibrational and molecular orientational degrees of freedom.\nOur BC simulation method is applied on the technologically relevant material\nCH$_{3}$NH$_{3}$PbI$_{3}$ (MAPI), finding giant BC isothermal entropy changes\n($|\\Delta S_{\\rm BC}| \\sim 10$ J K$^{-1}$ kg$^{-1}$) under moderate pressure\nshifts of $\\sim 0.1$ GPa. Intriguingly, our computational analysis of MAPI\nreveals that changes in the vibrational degrees of freedom of the molecular\ncations, not their reorientational motion, have a major influence on the\nentropy change that accompanies the order-disorder solid-solid phase\ntransition.",
        "positive": "Composition and optical properties of (In,Ga)As nanowires grown by\n  group-III-assisted molecular beam epitaxy: (In,Ga) alloy droplets are used to catalyse the growth of (In,Ga)As nanowires\nby molecular beam epitaxy on Si(111) substrates. The composition, morphology\nand optical properties of these nanowires can be tuned by the employed\nelemental fluxes. To incorporate more than 10% of In, a high In/(In+Ga) flux\nratio above 0.7 is required. We report a maximum In content of almost 30% in\nbulk (In,Ga)As nanowires for an In/(In+Ga) flux ratio of 0.8. However, with\nincreasing In/(In+Ga) fl ux ratio, the nanowire length and diameter are notably\nreduced. Using photoluminescence and cathodoluminescence spectroscopy on\nnanowires covered by a passivating (In,Al)As shell, two luminescence bands are\nobserved. A significant segment of the nanowires shows homogeneous emission,\nwith a wavelength corresponding to the In content in this segment, while the\nconsumption of the catalyst droplet leads to a spectrally-shifted emission band\nat the top of the nanowires. The (In,Ga)As nanowires studied in this work\nprovide a new approach for the integration of infrared emitters on Si\nplatforms."
    },
    {
        "anchor": "Estimation of the effects of Y and Zn atoms on the elastic properties of\n  Mg solid solution: Mg-based alloys have recently attracted major interest in view of their\npotential applications in the aerospace, aircraft and automotive industries.\nHere, we show that the effects of Y and Zn atoms on their compressibility can\nbe reliably estimated by a simple thermodynamical model deduced by means of\nfirst-principles calculations based on density functional theory that just\nappeared.",
        "positive": "Constructing coarse-grained skyrmion potentials from experimental data\n  with Iterative Boltzmann Inversion: In an effort to understand skyrmion behavior on a coarse-grained level,\nskyrmions are often described as 2D quasi particles evolving according to the\nThiele equation. Interaction potentials are the key missing parameters for\npredictive modeling of experiments. We apply the Iterative Boltzmann Inversion\ntechnique commonly used in soft matter simulations to construct potentials for\nskyrmion-skyrmion and skyrmion-magnetic material boundary interactions from a\nsingle experimental measurement without any prior assumptions of the potential\nform. We find that the two interactions are purely repulsive and can be\ndescribed by an exponential function for experimentally relevant skyrmions.\nThis captures the physics on experimental time and length scales that are of\ninterest for most skyrmion applications and typically inaccessible to atomistic\nor micromagnetic simulations."
    },
    {
        "anchor": "Realization of AlSb in the double layer honeycomb structure: a robust\n  new class of two-dimensional material: Exploring new two-dimensional (2D) van der Waals (vdW) systems is at the\nforefront of materials physics. Here, through molecular beam epitaxy on\ngraphene-covered SiC(0001), we report successful growth of AlSb in the\ndouble-layer honeycomb (DLHC) structure, a 2D vdW material which has no direct\nanalogue to its 3D bulk and is predicted kinetically stable when freestanding.\nThe structural morphology and electronic structure of the experimental 2D AlSb\nare characterized with spectroscopic imaging scanning tunneling microscopy and\ncross-sectional imaging scanning transmission electron microscopy, which\ncompare well to the proposed DLHC structure. The 2D AlSb exhibits a bandgap of\n0.93 eV versus the predicted 1.06 eV, which is substantially smaller than the\n1.6 eV of bulk. We also attempt the less-stable InSb DLHC structure; however,\nit grows into bulk islands instead. The successful growth of a DLHC material\nhere opens the door for the realization of a large family of novel 2D DLHC\ntraditional semiconductors with unique excitonic, topological, and electronic\nproperties.",
        "positive": "A comparative study of CO adsorption on flat, stepped and kinked Au\n  surfaces using density functional theory: Our ab initio calculations of CO adsorption energies on low miller index\n(111), (100), stepped (211), and kinked (532) gold surfaces show a strong\ndependence on local coordination with a reduction in Au atom coordination\nleading to higher binding energies. We find trends in adsorption energies to be\nsimilar to those reported in experiments and calculations for other metal\nsurfaces. The (532) surface provides insights into these trends because of the\navailability of a large number of kink sites which naturally have the lowest\ncoordination (6). We also find that, for all surfaces, an increase in CO\ncoverage triggers a decrease in the adsorption energy. Changes in the\nwork-function upon CO adsorption, as well as the frequencies of the CO\nvibrational modes are calculated, and their coverage dependence is reported."
    },
    {
        "anchor": "Spin orbit coupling and Lorentz force enhanced efficiency of TiO2 based\n  dye sensitized solar cells: We report on the effect of the strong spin orbit coupling and the Lorentz\nforce on the efficiency of TiO2 based dye sensitized solar cells. Upon\ninclusion of Ho2O3, due to the strong spin orbit coupling of the rare earth\nHo3+ ion, we do see 13 percent enhancement in the efficiency. We attribute such\nan enhancement in power conversion efficiency to the increased lifetime of the\nphoto-excited excitons. Essentially, a Ho3+ ion accelerates the phenomenon of\nthe spin rephasing or the intersystem crossing of the excitons in a\nphotosensitizer. Increase in the absorbance and decrease in the\nphotoluminescence intensity suggests a decrease in the recombination rate,\nhinting an enhanced charge transport and is in accordance with our\nelectrochemical impedance spectra and the J V characteristics. From the above\nwe strongly believe that enhanced efficiency of the device is due to increased\nintersystem crossing which would accelerate the exciton dissociation. On top of\nspin orbit interaction, a configuration where the electric and magnetic fields\nare perpendicular to each other helped in enhancing the efficiency by 16\npercent, suggesting that the Lorentz force also plays a dominant role in\ncontrolling the charge transport of the photo-generated charge carriers. We\nstrongly believe that this simple and novel strategy of improving the\nefficiency may pave the way for realizing higher efficiency dye sensitized\nsolar cells.",
        "positive": "Vibrational and optical properties of MoS$_2$: from monolayer to bulk: Molybdenum disulfide, MoS2, has recently gained considerable attention as a\nlayered material where neighboring layers are only weakly interacting and can\neasily slide against each other. Therefore, mechanical exfoliation allows the\nfabrication of single and multi-layers and opens the possibility to generate\natomically thin crystals with outstanding properties. In contrast to graphene,\nit has an optical gap of 1.9 eV. This makes it a prominent candidate for\ntransistor and opto-electronic applications. Single-layer MoS$_2$ exhibits\nremarkably different physical properties compared to bulk MoS$_2$ due to the\nabsence of interlayer hybridization. For instance, while the band gap of bulk\nand multi-layer MoS$_2$ is indirect, it becomes direct with decreasing number\nof layers. In this review, we analyze from a theoretical point of view the\nelectronic, optical, and vibrational properties of single-layer, few-layer and\nbulk MoS$_2$. In particular, we focus on the effects of spin-orbit interaction,\nnumber of layers, and applied tensile strain on the vibrational and optical\nproperties. We examine the results obtained by different methodologies, mainly\nab initio approaches. We also discuss which approximations are suitable for\nMoS$_2$ and layered materials. The effect of external strain on the band gap of\nsingle-layer MoS$_2$ and the crossover from indirect to direct band gap is\ninvestigated. We analyze the excitonic effects on the absorption spectra. The\nmain features, such as the double peak at the absorption threshold and the\nhigh-energy exciton are presented. Furthermore, we report on the phonon\ndispersion relations of single-layer, few-layer and bulk MoS$_2$. Based on the\nlatter, we explain the behavior of the Raman-active $A_{1g}$ and $E^1_{2g}$\nmodes as a function of the number of layers."
    },
    {
        "anchor": "Spectroscopic study of native defects in the semiconductor to metal\n  phase transition in V2O5 nanostructure: Vanadium is a transition metal with multiple oxidation states and V2O5 is the\nmost stable form among them. Besides catalysis, chemical sensing and\nphoto-chromatic applications, V2O5 is also reported to exhibit a semiconductor\nto metal transition (SMT) at a temperature range of 530-560K. Even though,\nthere are debates in using the term 'SMT' for V2O5, the metallic behavior above\ntransition temperature and its origin are of great interests in the scientific\ncommunity. In this study, V2O5 nanostructures were deposited on SiO2/Si\nsubstrate by vapour transport method using Au as catalyst. Temperature\ndependent electrical measurement confirms the SMT in V2O5 without any\nstructural change. Temperature dependent photoluminescence analysis proves the\nappearance of oxygen vacancy related peaks due to reduction of V2O5 above the\ntransition temperature, as also inferred from temperature dependent Raman\nspectroscopic studies. The newly evolved defect levels in the V2O5 electronic\nstructure with increasing temperature is also understood from the downward\nshift of the bottom most split-off conduction bands due to breakdown of pd{\\pi}\nbonds leading to metallic behavior in V2O5 above the transition temperature.",
        "positive": "Symmetry breaking in frustrated systems: effective fluctuation spectrum\n  due to coupling effects: We study the Langevin dynamics of a d-dimensional Ginzburg-Landau Hamiltonian\nwith isotropic long range repulsive interactions. We show that, once the\nsymmetry is broken, there is a coupling between the mean value of the local\nfield and its fluctuations, generating an anisotropic effective fluctuation\nspectrum. This anisotropy has many interesting dynamical consequences. In the\ninfinite time limit, static results are recovered which can be compared with\nthe well known Brazovskii's transition to a state with modulated order. Our\nstudy reveals that the modulated solution appears continuously in d = 3\ncontrary to what is found in the usual approach neglecting coupling of modes,\nwhile for d < 3 transitions are still discontinuous. Analytical results for\npositional and orientational order parameters are also obtained and interpreted\nin the context of recent discussions."
    },
    {
        "anchor": "Ammonium Fluoride as a Hydrogen-disordering Agent for Ice: The removal of residual hydrogen disorder from various phases of ice with\nacid or base dopants at low temperatures has been a focus of intense research\nfor many decades. As an antipode to these efforts, we now show using neutron\ndiffraction that ammonium fluoride (NH4F) is a hydrogen-disordering agent for\nthe hydrogen-ordered ice VIII. Cooling its hydrogen-disordered counterpart ice\nVII doped with 2.5 mol% ND4F under pressure leads to a hydrogen-disordered ice\nVIII with ~31% residual hydrogen disorder illustrating the long-range\nhydrogen-disordering effect of ND4F. The doped ice VII could be supercooled by\n~20 K with respect to the hydrogen-ordering temperature of pure ice VII after\nwhich the hydrogen-ordering took place slowly over a ~60 K temperature window.\nThese findings demonstrate that ND4F-doping slows down the hydrogen-ordering\nkinetics quite substantially. The partial hydrogen order of the doped sample is\nconsistent with the antiferroelectric ordering of pure ice VIII. Yet, we argue\nthat local ferroelectric domains must exist between ionic point defects of\nopposite charge. In addition to the long-range effect of NH4F-doping on\nhydrogen-ordered water structures, the design principle of using topological\ncharges should be applicable to a wide range of other 'ice-rule' systems\nincluding spin ices and related polar materials.",
        "positive": "Structural, Thermal and Electrical properties of Poly(methyl\n  methacrylate)-CaCu3Ti4O12 composite sheets fabricated via melt mixing: Poly(Methyl Methacrylate) (PMMA) and CaCu3Ti4O12 (CCTO) composites were\nfabricated via melt mixing followed by hot pressing technique. These were\ncharacterized using X-ray diffraction (XRD), thermo gravimetric (TGA), Thermo\nMechanical (TMA), Differential scanning calorimetry (DSC), Fourier transform\ninfrared (FTIR), and Impedance analyser for their structural, thermal and\ndielectric properties. Composites were found to have better thermal stability\nthan that of pure PMMA. However, there was no significant difference in the\nglass transition (Tg) temperature between the polymer and the composite. The\nappearance of additional vibrational frequencies in the range 400-600 cm-1 in\nFTIR spectra indicated a possible interaction between PMMA and CCTO. The\ncomposite, with 38 Vol % of CCTO (in PMMA), exhibited remarkably low dielectric\nloss at high frequencies and the low frequency relaxation is attributed to the\nspace charge polarization/MWS effect. The origin of AC conductivity\nparticularly in the high frequency region was attributed to the electronic\npolarization."
    },
    {
        "anchor": "The effect of changing electrode metal on solution-processed flexible\n  titanium dioxide memristors: Flexible solution processed memristors show different behaviour dependent on\nthe choice of electrode material. Use of gold for both electrodes leads to\nswitchable WORM (Write Once Read Many times) resistive devices. Use of\naluminium for both electrodes increases the richness of behaviour allowing both\ncurved and triangular memristive switching resistance memories. A comparison\ndevice with an aluminium bottom electrode and gold top electrode only exhibited\nsignificant memristive resistance switching when the aluminium electrode was\nthe cathode, suggesting that the electrode is acting as a source/sink of oxygen\nanions. When the gold electrode was the cathode this electrode was deformed by\noxygen evolution. These results demonstrate that aluminium is helpful for\nstabilising and promoting memristive behaviour in sol-gel TiO$_2$ devices and\nthat changing electrodes from aluminium to gold creates fundamentally different\ndevice characteristics.",
        "positive": "Ultrahigh-Field Hole Cyclotron Resonance Absorption in InMnAs Films: We have carried out an ultrahigh-field cyclotron resonance study of p-type\nIn1-xMnxAs films, with Mn composition x ranging from 0% to 2.5%, grown on GaAs\nby low-temperature molecular-beam epitaxy. Pulsed magnetic fields up to 500 T\nwere used to make cyclotron resonance observable in these low-mobility samples.\nThe clear observation of hole cyclotron resonance is direct evidence of the\nexistence of a large number of itinerant, effective-mass-type holes rather than\nlocalized d-like holes. It further suggests that the p-d exchange mechanism is\nmore favorable than the double exchange mechanism in this narrow gap InAs-based\ndilute magnetic semiconductor. In addition to the fundamental heavy-hole and\nlight-hole cyclotron resonance absorption appearing near the\nhigh-magnetic-field quantum limit, we observed many inter-Landau-level\nabsorption bands whose transition probabilities are stronglydependent on the\nsense of circular polarization of the incident light."
    },
    {
        "anchor": "Collective modes in uniaxial incommensurate-commensurate systems with\n  the real order parameter: The basic Landau model for uniaxial systems of the II class is nonintegrable,\nand allows for various stable and metastable periodic configurations, beside\nthat representing the uniform (or dimerized) ordering. In the present paper we\ncomplete the analysis of this model by performing the second order variational\nprocedure, and formulating the combined Floquet-Bloch approach to the ensuing\nnonstandard linear eigenvalue problem. This approach enables an analytic\nderivation of some general conclusions on the stability of particular states,\nand on the nature of accompanied collective excitations. Furthermore, we\ncalculate numerically the spectra of collective modes for all states\nparticipating in the phase diagram, and analyze critical properties of\nGoldstone modes at all second order and first order transitions between\ndisordered, uniform and periodic states. In particular it is shown that the\nGoldstone mode softens as the underlying soliton lattice becomes more and more\ndilute.",
        "positive": "The relativistic 5f electronic structure of delocalized $\u03b1$-U and\n  localized $\u03b4$-Pu from the self consistent vertex corrected GW approach\n  and X-ray Emission Spectroscopy: The recently developed self-consistent vertex corrected GW method is used to\ncalculate the 5f electronic structure in delocalized $\\alpha$-U and localized\n$\\delta$-Pu, each of which is confirmed by the historical experimental\napproaches of direct and inverse photoemission. Tender X-Ray Emission\nSpectroscopy (XES), in a novel application to 5f electronic structure, is used\nto experimentally prove the existence of 5f delocalization in $\\alpha$-U."
    },
    {
        "anchor": "Variational-asymptotic homogenization of thermoelastic periodic\n  materials with thermal relaxation: A multiscale asymptotic homogenization method for periodic microstructured\nmaterials in presence of thermoelasticity with periodic spatially dependent one\nrelaxation time is introduced. The asymptotic expansions of the\nmicro-displacement and the micro-temperature fields are rewritten on the\ntransformed Laplace space and expressed as power series of the microstructural\nlength scale, leading to a set of recursive differential problems over the\nperiodic unit cell. The solution of such cell problems leads to the\nperturbation functions. Up-scaling and down-scaling relations are then defined,\nand the latter allow expressing the microscopic fields in terms of the\nmacroscopic ones and their gradients. Average field equations of infinite order\nare also derived. The efficiency of the proposed technique was tested in\nrelation to a bi dimensional orthotropic layered body with orthotropy axis\nparallel to the direction of the layers, where the mechanical and temperature\nconstitutive properties were well stabilised. The dispersion curves of the\nhomogenized medium, truncated at the first order are compared with the\ndispersion curves of the heterogeneous continuum obtained by the Floquet-Bloch\ntheory. The results obtained with the two different approaches show a very good\nagreement.",
        "positive": "Effects of Bending on Raman-active Vibration Modes of Carbon Nanotubes: We investigate vibration modes and their Raman activity of single-walled\ncarbon nanotubes that are bent within their intrinsic elastic limits. By\nimplementing novel boundary conditions for density-functional based\ntight-binding, and using non-resonant bond polarization theory, we discover\nthat Raman activity can be induced by bending. Depending on the degree of\nbending, high-energy Raman peaks change their positions and intensities\nsignificantly. These effects can be explained by migration of nodes and\nantinodes along tube circumference. We discuss the challenge of associating the\npredicted spectral changes with experimental observations."
    },
    {
        "anchor": "Photorealistic modelling of metals from first principles: The colours of metals have attracted the attention of humanity since ancient\ntimes, and coloured metals, in particular gold compounds, have been employed\nfor tools and objects symbolizing the aesthetics of power. In this work we\ndevelop a comprehensive framework to obtain the reflectivity and colour of\nmetals, and show that the trends in optical properties and the colours can be\npredicted by straightforward first-principles techniques based on standard\napproximations. We apply this to predict reflectivity and colour of several\nelemental metals and of different types of metallic compounds (intermetallics,\nsolid solutions and heterogeneous alloys), considering mainly binary alloys\nbased on noble metals. We validate the numerical approach through an extensive\ncomparison with experimental data and the photorealistic rendering of known\ncoloured metals.",
        "positive": "Low-energy silicon allotropes with strong absorption in the visible for\n  photovoltaic applications: We present state-of-the-art first-principle calculations of the electronic\nand optical properties of silicon allotropes with interesting characteristics\nfor applications in thin-film solar cells. These new phases consist of\ndistorted sp$^3$ silicon networks and have a lower formation energy than other\nexperimentally produced silicon phases. Some of these structures turned out to\nhave quasi-direct and dipole-allowed band gaps in the range 0.8--1.5\\,eV, and\nto display absorption coefficients comparable with those of chalcopyrites used\nin thin-film record solar cells."
    },
    {
        "anchor": "Spatial reorientation of azobenzene side groups of a liquid crystalline\n  polymer induced with linearly polarized light: The photoinduced 3D orientational structures in the films of liquid\ncrystalline polyester, containing azobenzene side groups, are studied both\nexperimentally and theoretically. By using the null ellipsometry and the UV\nabsorption methods, preferential in-plane alignment of the azobenzene fragments\nand in-plane reorientation under irradiation with polarized UV light are\nestablished. The uniaxial and biaxial orientational configurations of the\nazobenzene chromophores are detected. The biaxiality is observed in the\nintermediate stages of irradiation, whereas the uniaxial structure is\nmaintained in the photosaturated state. The components of the order parameter\ntensor of the azobenzene fragments are estimated for the initial state and\nafter different doses of irradiation. The proposed theory takes into account\nbiaxiality of the induced structures. Numerical analysis of the master\nequations for the order parameter tensor is found to yield the results that are\nin good agreement with the experimental dependencies of the order parameter\ncomponents on the illumination time.",
        "positive": "Anisotropic Optical Properties of Layered Germanium Sulfide: Two-dimensional (2D) layered materials, transition metal dichalcogenides and\nblack phosphorus, have attracted much interest from the viewpoints of\nfundamental physics and device applications. The establishment of new\nfunctionalities in anisotropic layered 2D materials is a challenging but\nrewarding frontier, owing to their remarkable optical properties and prospects\nfor new devices. Here, we report the anisotropic optical properties of layered\n2D monochalcogenide of germanium sulfide (GeS). Three Raman scattering peaks\ncorresponding to the B3g, A1g, and A2g modes with strong polarization\ndependence are demonstrated in the GeS flakes, which validates polarized Raman\nspectroscopy as an effective method for identifying the crystal orientation of\nanisotropic layered GeS. Photoluminescence (PL) is observed with a peak at\naround 1.66 eV that originates from the direct optical transition in GeS at\nroom temperature. Moreover, determination of the polarization dependent\ncharacteristics of the PL and absorption reveals an anisotropic optical\ntransition near the band edge of GeS, which is also supported by the density\nfunctional theory calculations. This anisotropic layered GeS presents the\nopportunities for the discovery of new physical phenomena and will find\napplications that exploit its anisotropic properties."
    },
    {
        "anchor": "Composition determination of quaternary GaAsPN layers from single XRD\n  measurement of quasi-forbidden (002) reflection: GaAsPN layers with a thickness of 30nm were grown on GaP substrates with\nmetalorganic vapor phase epitaxy to study the feasibility of a single X-ray\ndiffraction (XRD) measurement for full composition determination of quaternary\nlayer material. The method is based on the peak intensity of a quasi-forbidden\n(002) reflection which is shown to vary with changing arsenic content for\nGaAsPN. The method works for thin films with a wide range of arsenic contents\nand shows a clear variation in the reflection intensity as a function of\nchanging layer composition. The obtained thicknesses and compositions of the\ngrown layers are compared with accurate reference values obtained by Rutherford\nbackscattering spectroscopy combined with nuclear reaction analysis\nmeasurements. Based on the comparison, the error in the XRD defined material\ncomposition becomes larger with increasing nitrogen content and layer\nthickness. This suggests that the dominating error source is the deteriorated\ncrystal quality due to the nonsubstitutional incorporation of nitrogen into the\ncrystal lattice and strain relaxation. The results reveal that the method\noverestimates the arsenic and nitrogen content within error margins of about\n0.12 and about 0.025, respectively.",
        "positive": "Influence of electric fields on absorption spectra of AAB-stacked\n  trilayer graphene: The band structures and optical properties of AAB-stacked trilayer graphenes\n(AAB-TLG) are calculated by the tight-binding model and gradient approximation.\nThree pairs of the energy bands exhibit very different energy dispersions at\nlow energy and saddle points at the middle energy. At zero electric field,\n$3$$^2$ excitation channels exist in both the low and middle frequencies, and\ncause the very rich joint density of states (JDOS). However, the structures in\nthe JDOS do not appear in the absorption spectra completely. Due to the\ndifferent contributions from the velocity metric elements, some excitation\ntransitions disappear in the spectra. Furthermore, the frequency and the\nexistence of the absorption structures are affected by the increase of the\nelectric field from zero."
    },
    {
        "anchor": "STM study of the preparation of clean Ta(110) and the subsequent growth\n  of two-dimensional Fe islands: This report deals with the preparation of a clean Ta(110) surface,\ninvestigated by means of scanning tunneling microscopy/spectroscopy as well as\nby low-energy electron diffraction and Auger electron spectroscopy. The surface\ninitially exhibits a surface reconstruction induced by oxygen contamination.\nThis reconstruction can be removed by annealing at high temperatures under\nultrahigh vacuum conditions. The reconstruction-free surface reveals a surface\nresonance at a bias voltage of about -500 mV. The stages of the transformation\nare presented and discussed. In a next step, Fe islands were grown on top of\nTa(110) and investigated subsequently. An intermixing regime was identified for\nannealing temperatures of (550 - 590) K.",
        "positive": "Mutual phase-locking in high frequency microwave nanooscillators as\n  function of field angle: We perform a qualitative analysis of phase locking in a double point-contact\nspinvalve system by solving the Landau-Lifshitz-Gilbert-Slonzewski equation\nusing a hybrid-finite-element method. We show that the phase-locking behaviour\ndepends on the applied field angle. Starting from a low field angle, the\nlocking-current difference between the current through contact A and B\nincreases with increasing angle up to a maximum of 14 mA at 30 degree and it\ndecreases thereafter until it reaches a minimum of 1 mA at 75 degree. The\ntunability of the phase-lock frequency with current decreases linearly with\nincreasing out of plane angle from 45 to 21 MHz/mA."
    },
    {
        "anchor": "First-principles study of structural disorder, site preference, chemical\n  bonding and transport properties of Mg-doped tetrahedrite: Tetrahedrite-based ($\\textrm{Cu}_{12}\\textrm{Sb}_{4}\\textrm{S}_{13}$)\nmaterials are candidates for good thermoelectric generators due to their\nintrinsic, very low thermal conductivity and high power factor. One of the\ncurrent limitations is virtual absence of tetrahedrites exhibiting n--type\nconductivity. In this work, first-principles calculations are carried out to\nstudy Mg-doped tetrahedrite,\n$\\textrm{Mg}_{x}\\textrm{Cu}_{12}\\textrm{Sb}_{4}\\textrm{S}_{13}$ with\npossibility of predicting n--type material in mind. Different concentrations\nand modifications of the structure are investigated for their formation\nenergies, preferred site occupation and change in local environment around\ndopants. Mg atoms tend to occupy 6b site, while introduced excess Cu prefers\n24g site. Introduction of elements in those sites display different effect on\nnearby rattling Cu(2) atom. Topological analysis shows that tetrahedrite\nexhibits ionic, closed-shell bonds with some degree of covalency. Majority of\nthe bonds weakens with increasing content of Mg; structure becomes increasingly\nless stable, which is also expressed by global instability and bond strain\nindexes. Achieving n--type conductivity was predicted by the calculations for\nstructures with $x>1.0$, however increasing enthalpy of formation and lack of\nstability might suggest limit of solubility and difficulties in obtaining those\nexperimentally.",
        "positive": "Simple model of the static exchange-correlation kernel of a uniform\n  electron gas with long-range electron-electron interaction: A simple approximate expression in real and reciprocal spaces is given for\nthe static exchange-correlation kernel of a uniform electron gas interacting\nwith the long-range part only of the Coulomb interaction. This expression\ninterpolates between the exact asymptotic behaviors of this kernel at small and\nlarge wave vectors which in turn requires, among other thing, information from\nthe momentum distribution of the uniform electron gas with the same interaction\nthat have been calculated in the G0W0 approximation. This exchange-correlation\nkernel as well as its complement analogue associated to the short-range part of\nthe Coulomb interaction are more local than the Coulombic exchange-correlation\nkernel and constitute potential ingredients in approximations for recent\nadiabatic connection fluctuation-dissipation and/or density functional theory\napproaches of the electronic correlation problem based on a separate treatment\nof long-range and short-range interaction effects."
    },
    {
        "anchor": "Hydrogen supersaturated layers in H/D plasma-loaded tungsten: A global\n  model based on thermodynamics, kinetics and density functional theory data: In this work, we combine Density Functional Theory data with a Thermodynamic\nand a kinetic model to determine the total concentration of hydrogen implanted\nin the sub-surface of tungsten exposed to a hydrogen flux. The sub-surface\nhydrogen concentration is calculated given a flux of hydrogen, a temperature of\nimplantation, and the energy of the incoming hydrogen ions as independent\nvariables. This global model is built step by step; an equilibrium between\natomic hydrogen within bulk tungsten and a molecular hydrogen gas phase is\nfirst considered, and the calculated solubility is compared with experimental\nresults. Subsequently, a kinetic model is used to determine the chemical\npotential for hydrogen in the sub-surface of tungsten. Combining both these\nmodels, two regimes are established in which hydrogen is preferentially trapped\nat either interstitial sites or in vacancies. We deduce from our model that the\nexistence of these two regimes is driven by the temperature of the implanted\ntungsten sample; above a threshold or transition temperature is the\ninterstitial regime, below is the vacancy regime in which super-saturated\nlayers form within tenths of angstrom below the surface. A simple analytical\nexpression is derived for the coexistence of the two regimes depending on the\nimplantation temperature, the incident energy and the flux of the hydrogen ions\nwhich we use to plot the corresponding phase diagram.",
        "positive": "Electronic and magnetic properties of substitutional Mn clusters in\n  (Ga,Mn)As: The magnetization and hole distribution of Mn clusters in (Ga,Mn)As are\ninvestigated by all-electron total energy calculations using the projector\naugmented wave method within the density-functional formalism. It is found that\nthe energetically most favorable clusters consist of Mn atoms surrounding one\ncenter As atom. As the Mn cluster grows the hole band at the Fermi level splits\nincreasingly and the hole distribution gets increasingly localized at the\ncenter As atom. The hole distribution at large distances from the cluster does\nnot depend significantly on the cluster size. As a consequence, the spin-flip\nenergy differences of distant clusters are essentially independent of the\ncluster size. The Curie temperature $T_C$ is estimated directly from these\nspin-flip energies in the mean field approximation. When clusters are present\nestimated $T_C$ values are around 250 K independent of Mn concentration whereas\nfor a uniform Mn distribution we estimate a $T_C$ of about 600 K."
    },
    {
        "anchor": "Multi-excitons in self-assembled InAs/GaAs quantum dots: A\n  pseudopotential, many-body approach: We use a many-body, atomistic empirical pseudopotential approach to predict\nthe multi-exciton emission spectrum of a lens shaped InAs/GaAs self-assembled\nquantum dot. We discuss the effects of (i) The direct Coulomb energies,\nincluding the differences of electron and hole wavefunctions, (ii) the exchange\nCoulomb energies and (iii) correlation energies given by a configuration\ninteraction calculation. Emission from the groundstate of the $N$ exciton\nsystem to the $N-1$ exciton system involving $e_0\\to h_0$ and $e_1\\to h_1$\nrecombinations are discussed. A comparison with a simpler single-band,\neffective mass approach is presented.",
        "positive": "A ternary map of Ni-Mn-Ga Heusler alloys from ab initio calculations: In the present work, the aspects of magnetic and structural properties of\nNi-Mn-Ga alloys are described in the framework of fist-principles approach and\nmapped into ternary composition diagrams. The stable atomic arrangement and\nmagnetic alignment for compositions with cubic austenite and tetragonal\nmartensite structures across phase diagrams are predicted. It is shown that Ni-\nand Ga-rich compositions possess the regular Heusler structure in contrast to\nMn-rich compositions with inverse Heusler structure as favorable one.\nCompositions with unstable austenite structure are concentrated in the left and\nright sides of diagram whereas compositions with unstable martensite structure\nare located in the low-middle part of diagram. The magnetic phase diagrams\nshowing regions with the ferromagnetic order and the complex ferrimagnetic\norder for austenitic and martensitic compositions are obtained. The results of\ncalculations are in a good agreement with available experimental data."
    },
    {
        "anchor": "Bilayer borophene: The effects of substrate and stacking: Bilayer borophene has recently attracted much interest due to its outstanding\nmechanical and electronic properties. The interlayer interactions of these\nbilayers are reported differently in theoretical and experimental studies.\nHerein, we design and investigate bilayer beta12-borophene, by first-principles\ncalculations. Our results show that the interlayer distance of the relaxed\nAA-stacked bilayer is about 2.5 A, suggesting a van der Waals (vdW) interlayer\ninteraction. However, this is not supported by previous experiments, therefore\nby constraining the interlayer distance, we propose a preferred model which is\nclose to experimental records. This preferred model has one covalent interlayer\nbond in every unit cell (single-pillar). Further, we argue that the preferred\nmodel is nothing but the relaxed model under a 2% compression. Additionally, we\ndesigned three substrate-supported bilayers on the Ag, Al, and Au substrates,\nwhich lead to double-pillar structures. Afterward, we investigate the AB\nstacking, which forms covalent bonds in the relaxed form, without the need for\ncompression or substrate. Moreover, phonon dispersion shows that, unlike the AA\nstacking, the AB stacking is stable in freestanding form. Subsequently, we\ncalculate the mechanical properties of the AA and AB stackings. The ultimate\nstrengths of the AA and the AB stackings are 29.72 N/m at 12% strain and 23.18\nN/m at 8% strain, respectively. Moreover, the calculated Young's moduli are 419\nN/m and 356 N/m for the AA and the AB stackings, respectively. These results\nshow the superiority of bilayer borophene over bilayer MoS2 in terms of\nstiffness and compliance. Our results can pave the way for future studies on\nbilayer borophene structures.",
        "positive": "High pressure induced precipitation in Al7075 alloy: Precipitate-matrix interactions govern the mechanical behavior of precipitate\nstrengthened Al-based alloys. These alloys find a wide range of applications\nranging from aerospace to automobile and naval industries due to their low cost\nand high strength to weight ratio. Structures made from Al-based alloys undergo\ncomplex loading conditions such as high strain rate impact, which involves high\npressures. Here we use diamond anvil cells to study the behavior of Al-based\nAl7075 alloy under quasi-hydrostatic and non-hydrostatic pressure up to ~53\nGPa. In situ X-ray diffraction (XRD) and pre- and post-compression transmission\nelectron microscopy (TEM) imaging are used to analyze microstructural changes\nand estimate high pressure strength. We find a bulk modulus of 75.2 +- 1.9 GPa\nusing quasi-hydrostatic pressure XRD measurements. XRD showed that\nnon-hydrostatic pressure leads to a significant increase in defect density and\npeak broadening with pressure cycling. XRD mapping under non-hydrostatic\npressure revealed that the region with the highest local pressure had the\ngreatest increase in defect nucleation, whereas the region with the largest\nlocal pressure gradient underwent texturing and had larger grains. TEM analysis\nshowed that pressure cycling led to the nucleation and growth of many\nprecipitates. The significant increase in defect and precipitate density leads\nto an increase in strength for Al7075 alloy at high pressures."
    },
    {
        "anchor": "Correlating Nanoscale Structure with Electrochemical Property of Solid\n  Electrolyte Interphases in Solid-State Battery Electrodes: Here, we correlate the nanoscale morphology and chemical composition of solid\nelectrolyte interphases (SEI) with the electrochemical property of\ngraphite-based composite electrodes. Using electrochemical strain microscopy\n(ESM) and X-ray photoelectron spectroscopy (XPS), changes of chemical\ncomposition and morphology (Li and F distribution) in SEI layers on the\nelectrodes as a function of solid electrolyte contents are analyzed. As a\nresult, we find a strong correlation between morphological variations on the\nelectrode, Li and F distribution in SEI layer, and Coulomb efficiency. This\ncorrelation determines the optimum composition of the composite electrode\nsurface that can maximize the physical and chemical uniformity of the solid\nelectrolyte on the electrode, which is a key parameter to increase\nelectrochemical performance in solid-state batteries.",
        "positive": "Structures and Optical Absorption of Bi2OS2 and LaOBiS2: The band gaps of isostructural Bi2OS2 and LaOBiS2 were examined using optical\nabsorption and discussed with the band structures calculated based on the\ncrystal structures determined using synchrotron X-ray diffraction. The Bi 6p\nand S 3p orbitals in the Bi-S plane were computationally predicted to\nconstitute the bands near the Fermi level. The optical reflectance spectra of\nBi2OS2 and LaOBiS2 showed optical band gaps of ca. 1.0 eV, which were close to\nthe computationally calculated direct band gaps of ca. 0.8 eV. Our results show\nthat Bi2OS2 and LaOBiS2 are semiconductors containing direct band gaps of\n0.8-1.0 eV, and they are suggested to be candidates for optoelectronic\nmaterials in the near-infrared region without highly toxic elements."
    },
    {
        "anchor": "Piezomagnetic effect as a counterpart of negative thermal expansion in\n  magnetically frustrated Mn-based antiperovskite nitrides: Electric-field control of magnetization promises to substantially enhance the\nenergy efficiency of device applications ranging from data storage to\nsolid-state cooling. However, the intrinsic linear magnetoelectric effect is\ntypically small in bulk materials. In thin films electric-field tuning of\nspin-orbit interaction phenomena (e.g., magnetocrystalline anisotropy) has been\nreported to achieve a partial control of the magnetic state. Here we explore\nthe piezomagnetic effect (PME), driven by frustrated exchange interactions,\nwhich can induce a net magnetization in an antiferromagnet and reverse its\ndirection via elastic strain generated piezoelectrically. Our $ab~initio$ study\nof PME in Mn-antiperovskite nitrides identified an extraordinarily large PME in\nMn$_3$SnN available at room temperature. We explain the magnitude of PME based\non features of the electronic structure and show an inverse-proportionality\nbetween the simulated zero-temperature PME and the negative thermal expansion\nat the magnetic (N\\'eel) transition measured by Takenaka et al. in 9\nantiferromagnetic Mn$_3$AN systems.",
        "positive": "Wavelength extension beyond 1.5 micrometer in symmetric InAs quantum\n  dots on InP(111)A using droplet epitaxy: By using a C3v symmetric (111) surface as a growth substrate, we are able to\nachieve high structural symmetry in self-assembled quantum dots, which are\nsuitable for use as quantum-entangled photon emitters. Here we report on the\nwavelength controllability of InAs dots on InP(111)A, which we realized by\ntuning the ternary alloy composition of In(Al,Ga)As barriers that were\nlattice-matched to InP. We changed the peak emission wavelength systematically\nfrom 1.3 to 1.7 micrometer by barrier band gap tuning. The observed spectral\nshift agreed with the result of numerical simulations that assumed a measured\nshape distribution independent of barrier choice."
    },
    {
        "anchor": "The Thiocyanate Anion is a Primary Driver of Carbon Dioxide Capture by\n  Ionic Liquids: Carbon dioxide, CO2, capture by room-temperature ionic liquids (RTILs) is a\nvivid research area featuring both accomplishments and frustrations. This work\nemploys the PM7-MD method to simulate adsorption of CO2 by\n1,3-dimethylimidazolium thiocyanate at 300 K. The obtained result evidences\nthat the thiocyanate anion plays a key role in gas capture, whereas the impact\nof the 1,3-dimethylimidazolium cation is mediocre. Decomposition of the\ncomputed wave function on the individual molecular orbitals confirms that\nCO2-SCN binding extends beyond just expected electrostatic interactions in the\nion-molecular system and involves partial sharing of valence orbitals.",
        "positive": "Modified Band Alignment Method to Obtain Hybrid Functional Accuracy from\n  Standard DFT: Application to Defects in Highly Mismatched III-V:Bi Alloys: This paper provides an accurate theoretical defect energy database for pure\nand Bi-containing III-V (III-V:Bi) materials and investigates efficient methods\nfor high-throughput defect calculations based on corrections of results\nobtained with local and semi-local functionals. Point defects as well as\nnearest-neighbor and second-nearest-neighbor pair defects were investigated in\ncharge states ranging from -5 to 5. Ga-V:Bi systems (GaP:Bi, GaAs:Bi, and\nGaSb:Bi) were thoroughly investigated with significantly slower, higher\nfidelity hybrid Heyd-Scuseria-Ernzerhof (HSE) and significantly faster, lower\nfidelity local density approximation (LDA) calculations. In both approaches\nspurious electrostatic interactions were corrected with the Freysoldt\ncorrection. The results were verified against available experimental results\nand used to assess the accuracy of a previous band alignment correction. Here,\na modified band alignment method is proposed in order to better predict the HSE\nvalues from the LDA ones. The proposed method allows prediction of defect\nenergies with values that approximate those from the HSE functional at the\ncomputational cost of LDA (about 20x faster for the systems studied here).\nTests of selected point defects in In-V:Bi materials resulted in corrected LDA\nvalues having a mean absolute error (MAE)=0.175 eV for defect levels vs. HSE.\nThe method was further verified on an external database of defects and\nimpurities in CdX (X=S, Se, Te) systems, yielding a MAE=0.194 eV. These tests\ndemonstrate the correction to be sufficient for qualitative and\nsemi-quantitative predictions, and may suggest transferability to many\nsemiconductor systems without significant loss in accuracy. Properties of the\nremaining In-V:Bi defects and all Al-V:Bi defects were predicted with the use\nof the modified band alignment method."
    },
    {
        "anchor": "Comment on the paper: \"Water content and its effect on ultrasound\n  propagation in concrete- the possibility of NDE\". Ultrasonic 38(2000) 546-552\n  by Etsuzo Ohdaira and Nobuyoshi Masuzawa: The fundamental application of the ultrasonic pulse velocity method (UPV) in\nthe study of concrete, consist in the analysis and estimation of the mechanical\nproperties (compressive strength). The precission of the estimation may be\ndependent on the incidence of various factors, one of which is the water\ncontent acquired by the sample of concrete. In [Etsuzo] a lineal dependence of\nthe UPV in terms of the water content for different dosifications of concrete\nis proposed. This paper presents an analysis of that dependence proving that an\nexponential model describes better the behavior of the velocity as function of\nwater content.",
        "positive": "Pressure-constant Monte Carlo simulation of phase I of solid CO2 up to\n  10 GPa at T = 200 K using Kihara potential model: This article is a continuation of the past three papers, arXiv:1711.04976\n(2017), arXiv:1809.04291 (2018), and arXiv:2006.09673v2 (2020), in which\nconfigurations of the molecules around a vacancy in solid CO2 with the Pa3\nstructure (phase I) were calculated by the Monte Carlo (MC) simulation\ntechnique at T < 200 K and at a nominal pressure of P = 1 atm using lattice\nconstants determined in reference to experimental data. For the intermolecular\npotential, the Kihara model of a rod-shape core with zero diameter was used.\nFor theoretical consistency, however, the lattice constant should be determined\nby a pressure-constant MC simulation, i.e. by the NPT simulation. It was\nanticipated that the NPT simulation, successful for monoatomic molecular\nfluids, might not work straightforwardly for solid CO2 because of the\nnon-spherical molecular shape and interactions. In fact, it was found in the\npresent work that the protocol of the standard NPT simulation had to be\nmodified for solid CO2 to achieve an equilibrium lattice constant, given an\nexternal pressure, within practical computer time and capacity. The modified\nprotocol was used to calculate the P-V relation at 1 bar and from 2 to 10 GPa\nat which a structural phase transition is known to take place. The temperature\nwas fixed at 200 K. As a result, the calculated P-V relation was similar to\nthose in previous theoretical works, the molar volume being roughly 0.5 %\nsmaller than experimental data."
    },
    {
        "anchor": "Sc2CX (X=N2, ON, O2) MXenes as a promising anode material: A\n  first-principles study: MXenes' tunable properties make them excellent candidates for many\napplications in future nanoelectronics. In this work, we explore the\nsuitability of Sc$_2$CX (X=N$_2$, ON, O$_2$) MXenes to act as the active anode\nmaterials in Na-ion based batteries (NIBs) by means of \\textsl{ab initio}\nsimulations. After analyzing the structural and elastic properties of all the\npossible models to evaluate the energetically favorable N and O\nfunctionalization sites, our calculations show that both Sc$_2$CON and\nSc$_2$CN$_2$ present a clear metallic character, making them potential\ncandidates as anode materials. The investigation of the most relevant features\nfor anode performance, such as the adsorption and diffusion of Na atoms, the\nintrinsic capacity, the open circuit voltage, and the storage capacity show\nthat both systems are serious alternatives to the most common 2D materials\ncurrently employed in alkali metal batteries. In particular, Sc$_2$CN$_2$\npresents a better diffusion behavior thanks to the absence of Na clustering on\nits surface, with optimal diffusion barriers comparable to other 2D materials\nsuch as MoN$_2$, while the values of diffusion barriers for Sc$_2$CON are at\nleast three times smaller than those found for other anode candidates.\nSimilarly, while the capacity of Sc$_2$CON is close to the one reported for 2D\nSc$_2$C, Sc$_2$CN$_2$ possesses a power density more than twice higher than the\nones of 2D materials such as Sc$_2$C, graphite, and MoS$_2$. Our results thus\nconfirm the urge for further experimental exploration of the MXene Sc$_2$CX\n(X=N$_2$, ON, O$_2$) family as anode material in NIBs.",
        "positive": "Intrinsic chiral field as vector potential of the magnetic current in\n  the zig-zag lattice of magnetic dipoles: Chiral magnetic insulators manifest novel phases of matter where the sense of\nrotation of the magnetization is associated with exotic transport phenomena.\nEffective control of such phases and their dynamical evolution points to the\nsearch and study of chiral fields like the Dzyaloshinskii-Moriya interaction.\nHere we combine experiments, numerics, and theory to study a zig-zag dipolar\nlattice as a model of an interface between magnetic in-plane layers with\nperpendicular magnetization. The zig-zag lattice comprises two parallel\nsublattices of dipoles with perpendicular easy plane of rotation. The dipolar\nenergy of the system is exactly separable into a sum of symmetric and\nantisymmetric long-range exchange interactions between dipoles, where the\nantisymmetric coupling generates a nonlocal Dzyaloshinskii-Moriya field which\nstabilizes winding textures with the form of chiral solitons. The\nDzyaloshinskii-Moriya interaction acts as a vector potential or gauge field of\nthe magnetic current and gives rise to emergent magnetic and electric fields\nthat allow the manifestation of the magnetoelectric effect in the system."
    },
    {
        "anchor": "Seebeck-driven transverse thermoelectric generation in on-chip devices: An unconventional approach to enhance the transverse thermopower by combining\nmagnetic and thermoelectric materials, namely the Seebeck-driven transverse\nthermoelectric generation (STTG), has been proposed and demonstrated recently.\nHere, we improve on the previously used sample structure and achieve large\ntransverse thermopower over 40 $\\mu$V K$^{-1}$ due to STTG in on-chip devices.\nWe deposited polycrystalline Fe-Ga alloy films directly on n-type Si\nsubstrates, where Fe-Ga and Si serve as the magnetic and thermoelectric\nmaterials, respectively. Using microfabrication, contact holes were created\nthrough the SiO$_{x}$ layer at the top of Si to electrically connect the Fe-Ga\nfilm with the Si substrate. These thin devices with simple structure clearly\nexhibited enhancement of transverse thermopower due to STTG, and the obtained\nvalues agreed well with the estimation over a wide range of the size ratio\nbetween the Fe-Ga film and the Si substrate.",
        "positive": "Bandgap narrowing in Mn doped GaAs probed by room-temperature\n  photoluminescence: The electronic band structure of the (Ga,Mn)As system has been one of the\nmost intriguing problems in solid state physics over the past two decades.\nDetermination of the band structure evolution with increasing Mn concentration\nis a key issue to understand the origin of ferromagnetism. Here we present room\ntemperature photoluminescence and ellipsometry measurements of\nGa_{100%-x}Mn_{x}As alloy. The up-shift of the valence-band is proven by the\nred shift of the room temperature near band gap emission from the\nGa_{100%-x}Mn_{x}As alloy with increasing Mn content. It is shown that even a\ndoping by 0.02 at.% of Mn affects the valence-band edge and it merges with the\nimpurity band for a Mn concentration as low as 0.6 at.%. Both X-ray diffraction\npattern and high resolution cross-sectional TEM images confirmed full\nrecrystallization of the implanted layer and GaMnAs alloy formation."
    },
    {
        "anchor": "Novel Two-dimensional SiC2 Sheet with Full Pentagon Network: We propose a promising two-dimensional nano-sheet of SiC2 (SiC2-pentagon)\nconsisting of tetrahedral silicon atoms and triple-linked carbon atoms in a\nfully-pentagon network. The SiC2-pentagon with buckled configuration is more\nfavorable than its planar counterpart and previously proposed SiC2-silagraphene\nwith tetra-coordinate silicon atoms; and its dynamical stability is confirmed\nthrough phonon analyzing. Buckled SiC2-pentagon is an indirect-band-gap\nsemiconductor with a gap of 1.388 eV. However, its one-dimensional nanoribbons\ncan be metals or semiconductors depending on the edge type, shape, and\ndecoration. Finally, we propose a method to produce the buckled SiC2-pentagon\nthrough chemical exfoliation on the beta-SiC(001)-c(2*2) SDB surface.",
        "positive": "Molecular theory of graphene chemical modification: The chapter is devoted to chemical uniqueness of graphene. In view of\nmolecular theory, the latter is a consequence of benzenoid packing of carbon\natoms, based on three neighbors to each carbon atom leaving the atom fourth\nvalence electron (the odd one) on its own. Due to rather large C-C distances,\nthe odd electrons of graphene molecules are correlated whereupon the molecules\nare radicalized and molecular chemistry of graphene is the chemistry of\ndangling bonds. The chapter presents the description of the\nmolecular-theory-dangling-bond view on graphene molecule hydrogenation and\noxidation. Specific peculiarities of the graphene molecular chemistry related\nto size-dependent topochemical features are discussed, as well"
    },
    {
        "anchor": "Shear Stresses in Shock-Compressed Covalent Solids: Shear stresses are the driving forces for the creation of both point and\nextended defects in crystals subjected to high pressures and temperatures.\nRecently, we observed anomalous elastic materials response in shock-compressed\nsilicon and diamond in the course of our MD simulations and were able to relate\nthis phenomenon to non-monotonic dependence of shear stress on uniaxial\ncompression of the material. Here we report results of combined density\nfunctional theory (DFT) and classical interatomic potentials studies of shear\nstresses in shock compressed covalent solids such as diamond and silicon for\nthree low-index crystallographic directions, <100>, <110>, <111>. We observed a\nnon-monotonic dependence of DFT shear stresses for all three crystallographic\ndirections which indicates that anomalous elastic response of shock compressed\nmaterial is a real phenomenon and not an artifact of interatomic potentials\nused in MD simulations.",
        "positive": "Simulation of the band structure of InAs/GaSb type II superlattices\n  utilizing multiple energy band theories: Antimonide type II superlattices is expected to overtake HgCdTe as the\npreferred materials for infrared detection due to their excellent photoelectric\nproperties and flexible and adjustable band structures. Among these compounds,\nInAs/GaSb type II superlattices represents the most commonly studied materials.\nHowever, the sophisticated physics associated with the antimonide-based bandgap\nengineering concept started at the beginning of 1990s gave a new impact and\ninterest in development of infrared detector structures within academic and\nnational laboratories. InAs/GaSb superlattices is a type II disconnected band\nstructure with electrons and holes confined in the InAs and GaSb layers,\nrespectively. The electron micro-band and hole micro-band can be regulated\nseparately by adjusting the InAs and GaSb layers, which facilitates the design\nof superlattice structures and maximizes the amount of energy band offset.\nThese works constituted a theoretical basis for the effective utilization of\nthe InAs/GaSb system in material optimization and designing new SL structures;\nthey also provided an opportunity for the preparation and rapid development of\nInAs/GaSb T2SLs. In this paper, we systematically review several widely used\nmethods for simulating superlattice band structures, including the kp\nperturbation method, envelope function approximation, empirical pseudopotential\nmethod, empirical tight-binding method, and first-principles calculations. With\nthe limitations of different theoretical methods proposed, the simulation\nmethods have been modified and developed to obtain reliable InAs/GaSb SL energy\nband calculation results. The objective of this work is to provide a reference\nfor designing InAs/GaSb type II superlattice band structures."
    },
    {
        "anchor": "Atoms of None of the Elements Ionize While Atoms of Inert Behavior Split\n  by Photonic Current: It is customary to refer to atoms by stating positive or negative charges\nwhen they lose or gain electrons. However, thinking about the related\nprinciples and phenomena of ionization has become confusing. It is also\nnecessary to realize that atoms of suitable elements can execute the interstate\ndynamics of qualified electrons. Atoms also undertake transition states. Atoms\ncan elongate. Atoms can expand. Atoms can contract. Under a suitable input\npower, flowing inert gas atoms can split. Upon splitting, inert gas atoms are\nconverted into electron streams. By carrying photons, when electron streams\nimpinge on atoms, atoms with solid behavior further elongate. Otherwise,\nelongated atoms at least deform. These atomic behaviors validate that they\ncannot ionize. When the flowing inert gas atoms split, the characteristics of\nthe photons become apparent. The splitting of inert gas atoms, the carrying of\nphotons by electron streams, and the lighting of traveling photons validate\nthat an electric current is a photonic current. The surface and interface\nimages of differently processed materials resulting from various microscopic\ninvestigations are due to the resolving powers of the characteristic photons.\nSeveral well-known principles also validate that an electric current is a\nphotonic current. This study enables us to understand the basic and applied\nsciences.",
        "positive": "Monte Carlo simulation of GaAs(001) homoepitaxy: By carrying out Monte Carlo simulations based on the two-species atomic-scale\nkinetic growth model of GaAs(001) homoepitaxy and comparing the results with\nscanning tunneling microscope images, we show that initial growing islands\nundergo the structural transformation before adopting the proper beta2(2x4)\nreconstruction."
    },
    {
        "anchor": "Phonons and Oxygen Diffusion in Bi2O3 and (Bi0.7Y0.3)2O3: We report investigation of phonons and oxygen diffusion in Bi2O3 and\n(Bi0.7Y0.3)2O3. The phonon spectra have been measured in Bi2O3 at high\ntemperatures up to 1083 K using inelastic neutron scattering. Ab-initio\ncalculations have been used to compute the individual contributions of the\nconstituent atoms in Bi2O3 and (Bi0.7Y0.3)2O3 to the total phonon density of\nstates. Our computed results indicate that as temperature is increased, there\nis a complete loss of sharp peak structure in the vibrational density of\nstates. Ab-initio molecular dynamics simulations show that even at 1000 K in\n{\\delta}-phase Bi2O3, Bi-Bi correlations remain ordered in the crystalline\nlattice while the correlations between O-O show liquid like disordered\nbehavior. In the case of (Bi0.7Y0.3)2O3, the O-O correlations broadened at\naround 500 K indicating that oxygen conductivity is possible at such low\ntemperatures in (Bi0.7Y0.3)2O3 although the conductivity is much less than that\nobserved in the undoped high temperature {\\delta}-phase of Bi2O3. This result\nis consistent with the calculated diffusion coefficients of oxygen and\nobservation by QENS experiments. Our ab-initio molecular dynamics calculations\npredict that macroscopic diffusion is attainable in (Bi0.7Y0.3)2O3 at much\nlower temperatures, which is more suited for technological applications. Our\nstudies elucidate the easy directions of diffusion in {\\delta}-Bi2O3 and\n(Bi0.7Y0.3)2O3.",
        "positive": "2D and 3D topological phases in BiTe$X$ compounds: Recently, it was shown that quantum spin Hall insulator (QSHI) phase with a\ngap wide enough for practical applications can be realized in the ultra thin\nfilms constructed from two inversely stacked structural elements of trivial\nband insulator BiTeI. Here, we study the edge states in the free-standing\nBi$_2$Te$_2$I$_2$ sextuple layer (SL) and the electronic structure of the\nBi$_2$Te$_2$I$_2$ SL on the natural BiTeI substrate. We show that the\ntopological properties of the Bi$_2$Te$_2$I$_2$ SL on this substrate keep\n$\\mathbb Z_2$ invariant. We also demonstrate that ultra thin centrosymmetric\nfilms constructed in the similar manner but from related material BiTeBr are\ntrivial band insulators up to five-SL film thickness. In contrast to\nBi$_2$Te$_2$I$_2$ for which the stacking of nontrivial SLs in 3D limit gives a\nstrong topological insulator (TI) phase, strong TI is realized in 3D\nBi$_2$Te$_2$Br$_2$ in spite of the SL is trivial. For the last material of the\nBiTe$X$ ($X$=I,Br,Cl) series, BiTeCl, both 2D and 3D centrosymmetric phases are\ncharacterized by topologically trivial band structure."
    },
    {
        "anchor": "Towards quantification of the ratio of the single and double wall carbon\n  nanotubes in their mixtures:An In situ Raman spectroelectrochemical study: Mixtures containing different weight ratios of single wall carbon nanotubes\n(SWCNT) and double wall carbon nanotubes (DWCNT) were prepared and studied by\nin-situ Raman spectroelectrochemistry. Two components of the G-prime mode in\nthe Raman spectra, which can be resolved at high electrode potentials, were\nassigned to the signals from inner tubes of DWCNT and outer tubes of DWCNT\ntogether with SWCNT. The dependence of the ratios of these two components of\nthe G-prime mode on the nominal amount of SWCNT and DWCNT in the samples was\nsimulated so that the residual amount of SWCNT in the original DWCNT could be\ndetermined. Additionally, the individual contributions of all components of\ncarbon nanotubes into the total area of the G-prime mode at high electrode\npotentials were estimated from the simulation.",
        "positive": "Electrical conduction processes in ZnO in a wide temperature range\n  20--500 K: We have investigated the electrical conduction processes in as-grown and\nthermally cycled ZnO single crystal as well as as-grown ZnO polycrystalline\nfilms over the wide temperature range 20--500 K. In the case of ZnO single\ncrystal between 110 and 500 K, two types of thermal activation conduction\nprocesses are observed. This is explained in terms of the existence of both\nshallow donors and intermediately deep donors which are consecutively excited\nto the conduction band as the temperature increases. By measuring the\nresistivity $\\rho(T)$ of a given single crystal after repeated thermal cycling\nin vacuum, we demonstrate that oxygen vacancies play an important role in\ngoverning the shallow donor concentrations but leave the activation energy\n($\\simeq27\\pm$2 meV) largely intact. In the case of polycrystalline films, two\ntypes of thermal activation conduction processes are also observed between\n$\\sim$150 and 500 K. Below $\\sim$150 K, we found an additional conduction\nprocess due to the nearest-neighbor-hopping conduction mechanism which takes\nplace in the shallow impurity band. As the temperatures further decreases below\n$\\sim$80 K, a crossover to the Mott variable-range-hopping conduction process\nis observed. Taken together with our previous measurements on $\\rho (T)$ of ZnO\npolycrystalline films in the temperature range 2--100 K [Y. L. Huang {\\it et\nal.}, J. Appl. Phys. \\textbf{107}, 063715 (2010)], this work establishes a\nquite complete picture of the overall electrical conduction mechanisms in the\nZnO material from liquid-helium temperatures up to 500 K."
    },
    {
        "anchor": "Anisotropic Dielectric Breakdown Strength of Single Crystal Hexagonal\n  Boron Nitride: Dielectric breakdown has historically been of great interest from the\nperspectives of fundamental physics and electrical reliability. However, to\ndate, the anisotropy in the dielectric breakdown has not been discussed. Here,\nwe report an anisotropic dielectric breakdown strength (EBD) for h-BN, which is\nused as an ideal substrate for two-dimensional (2D) material devices. Under a\nwell-controlled relative humidity, EBD values in the directions both normal and\nparallel to the c axis (EBD+c & EBD//c) were measured to be 3 and 12 MV/cm,\nrespectively. When the crystal structure is changed from sp3 of cubic-BN (c-BN)\nto sp2 of h-BN, EBD+c for h-BN becomes smaller than that for c-BN, while EBD//c\nfor h-BN drastically increases. Therefore, h-BN can possess a relatively high\nEBD concentrated only in the direction parallel to the c axis by conceding a\nweak bonding direction in the highly anisotropic crystal structure. This\nexplains why the EBD//c for h-BN is higher than that for diamond. Moreover, the\npresented EBD value obtained from the high quality bulk h-BN crystal can be\nregarded as the standard for qualifying the crystallinity of h-BN layers grown\nvia chemical vapor deposition for future electronic applications.",
        "positive": "Pressure-induced Topological Phase Transitions in Rock-salt\n  Chalcogenides: By means of a comprehensive theoretical investigation, we show that external\npressure can induce topological phase transitions in IV-VI semiconducting\nchalcogenides with rock-salt structure. These materials satisfy mirror\nsymmetries that are needed to sustain topologically protected surface states,\nat variance with time-reversal symmetry responsible for gapless edge states in\n$\\mathcal{Z}_{2}$ topological insulators. The band inversions at high-symmetry\npoints in the Brillouin zone that are related by mirror symmetry, are brought\nabout by an \"asymmetric\" hybridization between cation and anion $sp$ orbitals.\nBy working out the microscopic conditions to be fulfilled in order to maximize\nthis hybridization, we identify materials in the rock-salt chalcogenide class\nthat are prone to undergo a topological phase transition induced by pressure\nand/or alloying. Our model analysis is fully comfirmed by complementary\nadvanced \\textit{first-principles} calculations and \\textit{ab initio}-based\ntight-binding simulations."
    },
    {
        "anchor": "Electric control of antiferromagnets: In the past five years, most of the paradigmatic concepts employed in\nspintronics have been replicated substituting ferromagnets by antiferromagnets\nin critical parts of the devices. The numerous research efforts directed to\nmanipulate and probe the magnetic moments in antiferromagnets have been\ngradually established a new and independent field known as antiferromagnetic\nspintronics. In this paper, we focus on the electrical control and detection of\nantiferromagnetic moments at a constant temperature. We address separately the\nexperimental results concerning insulating and metallic thin films as they\ncorrespond to voltage and electrical current controlled devices, respectively.\nFirst, we present results on the voltage control of antiferromagnetic order in\ninsulating thin films. The experiments show that voltage pulses can switch the\nchirality of a modulated antiferromagnetic structure. Second, we describe the\nrecent advances in metallic antiferromagnetic systems. We present results\nobtained with the first USB-operated portable device able to perform the\nnon-volatile electrical current-induced switching of an antiferromagnet\ncombined with magnetoresistive readout at room temperature. We discuss on\npotential applications that can be realized using antiferromagnetic memory\ncells.",
        "positive": "Colossal Spin-Phonon Anomalies and the Ferroelectric Phase Transition in\n  the Model Multiferroic Bifeo3: We report a temperature-dependent Raman and neutron scattering investigation\nof the multiferroic material bismuth ferrite BiFeO3 (BFO)."
    },
    {
        "anchor": "van der Waals Interactions Between Thin Metallic Wires and Layers: Quantum Monte Carlo (QMC) methods have been used to obtain accurate\nbinding-energy data for pairs of parallel thin metallic wires and layers\nmodeled by 1D and 2D homogeneous electron gases. We compare our QMC binding\nenergies with results obtained within the random phase approximation, finding\nsignificant quantitative differences and disagreement over the asymptotic\nbehavior for bilayers at low densities. We have calculated pair-correlation\nfunctions for metallic biwire and bilayer systems. Our QMC data could be used\nto investigate van der Waals energy functionals.",
        "positive": "Large anomalous Hall effect in single crystals of the kagome Weyl\n  ferromagnet Fe$_3$Sn: The material class of kagome metals has rapidly grown and has been\nestablished as a field to explore the interplay between electronic topology and\nmagnetism. In this work, we report a combined theoretical and experimental\nstudy of the anomalous Hall effect of the ferromagnetic kagome metal Fe$_3$Sn.\nThe compound orders magnetically at 725 K and presents an easy-plane\nanisotropy. Hall measurements in single crystals below room temperature yield\nan anomalous Hall conductivity $\\sigma_{xy}\\sim500\\,(\\Omega\\textrm{cm})^{-1}$,\nwhich is found to depend weakly on temperature. This value is in good agreement\nwith the band-intrinsic contribution obtained by density-functional\ncalculations. Our calculations also yield the correct magnetic anisotropy\nenergy and predict the existence of Weyl nodes near the Fermi energy."
    },
    {
        "anchor": "The super-super exchange mechanism in iron-based antiperovskite\n  chalco-halides: By using the first-principles electronic structure calculations, we have\nsystematically studied the magnetism in three recently synthesized iron-based\nantiperovskite chalco-halides: Ba$_3$(FeS$_4$)Cl, Ba$_3$(FeS$_4$)Br, and\nBa$_3$(FeSe$_4$)Br. These compounds consist of edge-sharing Ba$Q_6$ ($Q$=Cl or\nBr) octahedra intercalated with isolated Fe$X_4$ ($X$=S or Se) tetrahedra. We\nfind that even though the shortest distances between the nearest-neighboring Fe\natoms in these three compounds already exceed 6 \\AA, much larger than the bond\nlength of a chemical bonding, they all remarkably show antiferromagnetic (AFM)\ncoupling along $b$ axis with very weak spin-spin correlation along $a$ axis.\nOur study shows that the mechanism underlying this novel AFM coupling is such a\nnew type of exchange interaction between the nearest-neighboring Fe-based\nsuper-moments mediated by Ba cations, which we call the super-super exchange\ninteraction, in which each magnetic Fe atom partially polarizes its four\nnearest-neighboring $X$ atoms to form a super-moment through $p$-$d$ orbital\nhybridization and the $X$ atoms in neighboring Fe$X_4$ tetrahedra along $b$\naxis antiferromagnetically couple with each others through the intermediate Ba\ncations. Different from the conventional superexchange, here it is cations\nrather than anions that mediate two neighboring super-moments. According to the\ncalculated strength of the AFM coupling, we predict that among these compounds\nthe highest AFM phase transition temperature $T_N$ may reach 110 K in\nBa$_3$(FeSe$_4$)Br, in comparison with the observed $T_N$s of 84 K in\nBa$_3$(FeS$_4$)Br and 95 K in Ba$_3$(FeS$_4$)Cl.",
        "positive": "Identifying the Alloy Structures of Germanene Grown on Al(111) Surface: While the growth of germanene has been claimed on many substrates, the exact\ncrystal structures remain controversial. Here, we systematically explore the\npossible structures formed by Ge deposition onto Al(111) surface by combining\ndensity-functional theory (DFT) and global optimization algorithm. We show\nthat, by high-level random-phase approximation (RPA) calculations, the\nformation of germanene on Al(111) is energetically unfavorable with positive\nformation energy. The two experimental phases are identified as honeycomb\nalloys Al3Ge3/Al(111)(r7xr7) and Al3Ge4/Al(111)(3x3), by combining ab initio\nevolutionary simulations, RPA calculations, and available experimental data\nfrom scanning tunneling microscopy (STM) and low-energy electron diffraction\n(LEED). Al3Ge4/Al(111)(3x3) is an interesting structure with a vacancy in the\nsubstrate, which accounts for the dark clover pattern in the experimental STM\nimage. Our results clarify the structural controversy of the Ge/Al(111) system\nand indicate the fabrication of germanene may remain challenging."
    },
    {
        "anchor": "Strained Si, Ge and SiGe alloys modeling with full-zone k.p method\n  optimized from first principle calculation: The electronic energy band structure of strained and unstrained Si, Ge and\nSiGe alloys is examined in this work using thirty-level k.p analysis. The\nenergy bands are at first obtained with ab initio calculations based on the\nLocal-Density-Approximation of Density-Functional Theory, including a GW\ncorrection and relativistic effects. The so-calculated band structure is then\nused to extract the unknown k.p fitting parameters with a conjugate-gradient\noptimization procedure. In a similar manner, the results of ab initio\ncalculations for strained materials are used to fit the unknown deformation\npotentials that are included in the present k.p Hamiltonian following the Pikus\nand Bir correction scheme. We show that the present k.p model is an efficient\nnumerical method, as far as computational time is concerned, that reproduces\naccurately the overall band structure, as well as the bulk effective density of\nstates and the carrier effective masses, for both strained and unstrained\nmaterials. As an application, the present thirty-level k.p model is used to\ndescribe the band offsets and the variations of the carrier effective masses in\na strained material, a Si(1-x)Gex/Si(1-y)Gey layer system.",
        "positive": "Area-selective deposition and B $\u03b4$-doping of Si(100) with\n  BCl$_{3}$: B-doped $\\delta$-layers were fabricated in Si(100) using BCl$_{3}$ as a\ndopant precursor in ultrahigh vacuum. BCl$_{3}$ adsorbed readily at room\ntemperature, as revealed by scanning tunneling microscopy (STM) imaging.\nAnnealing at elevated temperatures facilitated B incorporation into the Si\nsubstrate. Secondary ion mass spectrometry (SIMS) depth profiling demonstrated\na peak B concentration $>$ 1.2(1) $\\times$ 10$^{21}$ cm$^{-3}$ with a total\nareal dose of 1.85(1) $\\times$ 10$^{14}$ cm$^{-2}$ resulting from a 30 L\nBCl$_{3}$ dose at 150 $^{\\circ}$C. Hall bar measurements of a similar sample\nwere performed at 3.0 K revealing a sheet resistance of $R_{\\mathrm{s}}$ = 1.91\nk$\\Omega\\square^{-1}$, a hole concentration of $n$ = 1.90 $\\times$ 10$^{14}$\ncm$^{-2}$ and a hole mobility of $\\mu$ = 38.0 cm$^{2}$V$^{-1}$s$^{-1}$ without\nperforming an incorporation anneal. Further, the conductivity of several\nB-doped $\\delta$-layers showed a log dependence on temperature suggestive of a\ntwo-dimensional system. Selective-area deposition of BCl$_{3}$ was also\ndemonstrated using both H- and Cl-based monatomic resists. In comparison to a\ndosed area on bare Si, adsorption selectivity ratios for H and Cl resists were\ndetermined by SIMS to be 310(10):1 and 1529(5):1, respectively, further\nvalidating the use of BCl$_{3}$ as a dopant precursor for atomic precision\nfabrication of acceptor-doped devices in Si."
    },
    {
        "anchor": "Intrinsic life-time and external manipulation of Neel states in\n  antiferromagnetic adatom spins on semiconductor surfaces: It has been proposed that antiferromagnetic Fe adatom spins on semiconductor\nCu-N surfaces can be used to store information [S. Loth {\\it et al}, Science\n\\textbf{335}, 196 (2012)]. Here, we investigate spin dynamics of such\nantiferromagnetic systems through Monte Carlo simulations. We find out the\ntemperature and size laws of switching rates of N\\'{e}el states and show that\nthe N\\'{e}el states can become stable enough for the information storage when\nthe number of spins reaches to one or two dozens of the Fe spins. We also\nexplore promising methods for manipulating the N\\'{e}el states. These could\nhelp realize information storage with such antiferromagnetic spin systems.",
        "positive": "Virtual trions in the photoluminescence of monolayer transition-metal\n  dichalcogenides: Photoluminescence experiments from monolayer transition-metal dichalcogenides\noften show that the binding energy of trions is conspicuously similar to the\nenergy of optical phonons. This enigmatic coincidence calls into question\nwhether phonons are involved in the radiative recombination process. We address\nthis problem, unraveling an intriguing optical transition mechanism. Its\ninitial state is a localized charge (electron or hole) and delocalized exciton.\nThe final state is the localized charge, phonon and photon. In between, the\nintermediate state of the system is a virtual trion formed when the localized\ncharge captures the exciton through emission of the phonon. We analyze the\ndifference between radiative recombinations that involve real and virtual\ntrions (i.e., with and without a phonon), providing useful ways to distinguish\nbetween the two in experiment."
    },
    {
        "anchor": "Oscillatory tilt effect in a metal in a weak magnetic field: The oscillatory tilt effect in a normal metal at external magnetic field is\ndiscovered. The oscillatory tilt effect is characterized by the oscillations of\nultrasound attenuation in a metal at external magnetic field as predicted in\n[1]. The dimension of the non-central cross-section of the Fermi surface and\nthe velocity of electrons in a high pure Gallium single crystal at external\nmagnetic field are found. At the low frequencies of ultrasonic signal, the\n\"inverse\" oscillatory tilt effect in a high pure Gallium single crystal at the\nexternal magnetic field is observed.",
        "positive": "Strain-Enhanced Mobility of Monolayer MoS2: Strain engineering is an important method for tuning the properties of\nsemiconductors and has been used to improve the mobility of silicon transistors\nfor several decades. Recently, theoretical studies have predicted that strain\ncan also improve the mobility of two-dimensional (2D) semiconductors, e.g. by\nreducing intervalley scattering or lowering effective masses. Here, we\nexperimentally show strain-enhanced electron mobility in monolayer MoS2\ntransistors with uniaxial tensile strain, on flexible substrates. The on-state\ncurrent and mobility are nearly doubled with tensile strain up to 0.7%, and\ndevices return to their initial state after release of strain. We also show a\ngate-voltage-dependent gauge factor up to 200 for monolayer MoS2, which is\nhigher than previous values reported for sub-1 nm thin piezoresistive films.\nThese results demonstrate the importance of strain engineering 2D\nsemiconductors for performance enhancements in integrated circuits, or for\napplications such as flexible strain sensors."
    },
    {
        "anchor": "Effects of a Conducting Sphere Moving Through a Gradient Magnetic Field: We examine several conducting spheres moving through a magnetic field\ngradient. An analytical approximation is derived and an experiment is conducted\nto verify the analytical solution. The experiment is simulated as well to\nproduce a numerical result. Both the low and high magnetic Reynolds number\nregimes are studied. Deformation of the sphere is noted in the high Reynolds\nnumber case. It is suggested that this deformation effect could be useful for\ndesigning or enhancing present protection systems against space debris.",
        "positive": "Spin dynamics of electrons and holes interacting with nuclei in\n  MAPbI$_3$ perovskite single crystals: Methylammonium lead triiodine (MAPbI$_3$) is a material representative of the\nhybrid organic-inorganic lead halide perovskites which attract currently great\nattention due to their photovoltaic efficiency and bright optoelectronic\nproperties. Here, the coherent spin dynamics of charge carriers and spin\ndependent phenomena induced by the carrier interaction with nuclear spins are\nstudied in MAPbI$_3$ single crystals, using time-resolved Kerr rotation at\ncryogenic temperatures in magnetic fields up to 3 T. Spin dephasing times up to\na few nanoseconds and a longitudinal spin relaxation time of 37 ns are\nmeasured. The Larmor spin precession of both resident electrons and holes is\nidentified in the Kerr rotation signals. The Land\\'e factors ($g$-factors) in\nthe orthorhombic crystal phase show a strong anisotropy, ranging for the holes\nfrom $-0.28$ to $-0.71$ and for the electrons from $+2.46$ to $+2.98$, while\nthe $g$-factor dispersion of about 1% is rather small. An exciton $g$-factor of\n$+2.3$ is measured by magneto-reflectivity. A dynamic nuclear polarization by\nmeans of spin polarized electrons and holes is achieved in tilted magnetic\nfields giving access to the carrier-nuclei exchange interaction and the nuclei\nspin relaxation time exceeding 16 minutes."
    },
    {
        "anchor": "Hydrogen-induced metallization of the $\u03b2$-SiC(001) Si-rich surface: This paper has been withdrawn by the authors (see text).",
        "positive": "Photocatalytic Activity of Pulsed Laser Deposited TiO2 Thin Films: Nanostructured TiO2 thin films were prepared by pulsed laser deposition (PLD)\non indium doped tin oxide (ITO) substrates. Results from X-ray photoelectron\nspectroscopy (XPS) show that Ti 2p core level peaks shift toward the lower\nbinding energy with decrease in the buffer gas pressure (O2:Ar = 1:1). This\nsuggests that oxygen vacancies are created under insufficient oxygen\nconditions. Anatase to rutile ratio is also found to be system pressure\ndependent. Under deposition pressure of 750 mTorr only anatase phase was\nobserved even at 1073 K substrate temperature which is much higher that the\nbulk anatase to rutile phase transformation temperature. The deposited TiO2\nthin films were fabricated as photoanodes for photoelectrochemical (PEC)\nstudies. PEC measurements on TiO2 photoanodes show that the flatband potential\n(Vfb) increases by 0.088 eV on absolute vacuum energy scale (AVS) with decrease\nin the deposition pressure, from 750 to 250 mTorr at 873K. The highest incident\nphoton to current conversion efficiency [IPCE(lambda)] of 2.5 to 6 % was\nobtained from the thin films prepared at substrate temperature of 873K.\nCombining the results from XPS and PEC studies, we conclude that the deposition\npressure affects the concentration of the oxygen vacancies which changes the\nelectronic structure of the TiO2. With reference to photoelectrochemical\ncatalytic performance, our results suggest that it is possible to adjust the\nFermi energy level and structure of TiO2 thin films by controlling the buffer\ngas pressure and temperature to align the energy of the flatband potential\n(Vfb) with respect to specific redox species in the electrolyte."
    },
    {
        "anchor": "Femtosecond trimer quench cycled at megahertz rates in the\n  unconventional charge-density wave material $1\\textit{T'}-\\text{TaTe}_2$: Ultrafast optical switching of materials properties is of great relevance\nboth for future technological applications as well as gaining fundamental\nphysical insights to microscopic couplings and nonequilibrium phenomena.\nTransition-metal dichalcogenides (TMDCs) combine photo-sensitivity with strong\ncorrelations, furthering rich phase diagrams and enhanced tunability. Owing to\nits chemical composition, $1\\textit{T'}-\\text{TaTe}_2$ exhibits an\nelectronically and structurally unique set of charge-density waves (CDWs),\nfeaturing increased conductivity and a reduced prominence of amplitude modes.\nCompared to other charge-ordered TMDCs, only very few studies addressed the\nultrafast response of this material to optical excitation. In particular, the\nquestion whether such unconventional properties translate to unusual quench\ndynamics remains largely unresolved. Here, we investigate the structural\ndynamics in $1\\textit{T'}-\\text{TaTe}_2$ by means of ultrafast nanobeam\nelectron diffraction. The experiments are carried out with a tailored sample\ndesign that allows for excitation at 2$\\,$MHz repetition rate, higher than any\nstructural phase transformation probed thus far. Harnessing the enhanced\nresolution and sensitivity of this approach, we reveal a strongly directional\ncooperative atomic motion during the one-dimensional quench of the\nlow-temperature trimer lattice. These dynamics are completed within less than\n500$\\,$fs, substantially faster than reported previously. In striking contrast,\nthe periodic lattice distortion of the room-temperature phase is unusually\nrobust against high-density electronic excitation. In conjunction with the\nknown sensitivity of $1\\textit{T'}-\\text{TaTe}_2$ to chemical doping, we thus\nexpect the material to serve as a versatile platform for tunable structural\ncontrol by optical stimuli.",
        "positive": "Trap-Assisted Auger-Meitner Recombination from First Principles: Trap-assisted nonradiative recombination is known to limit the efficiency of\noptoelectronic devices, but the conventional multi-phonon emission (MPE)\nprocess fails to explain the observed loss in wide-band-gap materials. Here we\nhighlight the role of trap-assisted Auger-Meitner (TAAM) recombination, and\npresent a first-principles methodology to determine TAAM rates due to defects\nor impurities in semiconductors or insulators. We assess the impact on\nefficiency of light emitters in a recombination cycle that may include both\nTAAM and carrier capture via MPE. We apply the formalism to the technologically\nrelevant case study of a calcium impurity in InGaN, where a Shockley-Read-Hall\nrecombination cycle involving MPE alone cannot explain the experimentally\nobserved nonradiative loss. We find that, for band gaps larger than 2.5 eV, the\ninclusion of TAAM results in recombination rates that are orders of magnitude\nlarger than recombination rates based on MPE alone, demonstrating that TAAM can\nbe a dominant nonradiative process in wide-band-gap materials. Our\ncomputational formalism is general and can be applied to the calculation of\nTAAM rates in any semiconducting or insulating material."
    },
    {
        "anchor": "Multiple-scattering approach for multi-spin chiral magnetic\n  interactions: Application to the one- and two-dimensional Rashba electron gas: Various multi-spin magnetic exchange interactions (MEI) of chiral nature have\nbeen recently unveiled. Owing to their potential impact on the realisation of\ntwisted spin-textures, their implication in spintronics or quantum computing is\nvery promising. Here, I address the long-range behavior of multi-spin MEI on\nthe basis of a multiple-scattering formalism implementable in Green functions\nbased methods. I consider the impact of spin-orbit coupling (SOC) as described\nin the one- (1D) and two-dimensional (2D) Rashba model, from which the\nanalytical forms of the four- and six-spin interactions are extracted and\ncompared to the bilinear isotropic, anisotropic and Dzyaloshinskii-Moriya\ninteractions (DMI). Similarly to the DMI between two sites $i$ and $j$, there\nis a four-spin chiral vector perpendicular to the bond connecting the two\nsites. The oscillatory behavior of the MEI and their decay as function of\ninteratomic distances are analysed and quantified for the Rashba surfaces\nstates characterizing Au surfaces. The interplay of beating effects and\nstrength of SOC gives rise to a wide parameter space where chiral MEI are more\nprominent than the isotropic ones. The multi-spin interactions for a plaquette\nof $N$ magnetic moments decay like $\\{q_F^{N-d} P^{\\frac{1}{2}(d-1)}L\\}^{-1}$\nsimplifying to $\\{q_F^{N-d} R^{\\left[1+\\frac{N}{2}(d-1)\\right]}N\\}^{-1}$ for\nequidistant atoms, where $d$ is the dimension of the mediating electrons, $q_F$\nthe Fermi wave vector, $L$ the perimeter of the plaquette while $P$ is the\nproduct of interatomic distances. This recovers the behavior of the bilinear\nMEI, $\\{q_F^{2-d} R^{d}\\}^{-1}$, and shows that increasing the perimeter of the\nplaquette weakens the MEI. More important, the power-law pertaining to the\ndistance-dependent 1D MEI is insensitive to the number of atoms in the\nplaquette in contrast to the linear dependence associated with the 2D MEI.",
        "positive": "Poling effect on distribution of quenched random fields in a uniaxial\n  relaxor ferroelectric: The frequency dependence of the dielectric permitivity's maximum has been\nstudied for poled and unpoled doped relaxor strontium barium niobate\n$Sr_{0.61}Ba_{0.39}Nb_{2}O_{6}:Cr^{3+}$ (SBN-61:Cr). In both cases the maximum\nfound is broad and the frequency dispersion is strong. The present view of\nrandom fields compensation in the unpoled sample is not suitable for explaining\nthis experimental result. We propose a new mechanism where the dispersion of\nquenched random electric fields, affecting the nanodomains, is minimized after\npoling. We test our proposal by numerical simulations on a random field Ising\nmodel. Results obtained are in agreement with the polarization's measurements\npresented by Granzow et al. [Phys. Rev. Lett {\\bf 92}, 065701 (2004)]."
    },
    {
        "anchor": "Interplay between O defects and SiC stacking at the SiC/SiO$_2$\n  interface: We investigate the effect of SiC stacking on the 4H-SiC/SiO$_2$ interface,\nboth in the presence and absence of O defects, which appear during thermal\noxidation, via first principles calculations. It is known that 4H-SiC(0001) has\ntwo different surface types, depending on which of the two lattice sites, $h$\nor $k$, is at the surface [K. Arima \\textit{et al}., Appl. Phys. Lett.\n\\textbf{90}, 202106 (2007)]. We find interlayer states along the conduction\nband edge of SiC, whose location changes depending on the interface type, and\nthus too the effect of defects. When $h$ sites are directly at the interface, O\ndefects remove interfacial conduction band edge states. On the other hand, when\n$k$ sites are at the interface, the conduction band edge is insensitive to the\npresence of O defects. These differences will impact on the operation of SiC\ndevices because the most commonly used SiC based metal-oxide-semiconductor\nfield-effect transistors rely on the electronic structure of the conduction\nband.",
        "positive": "First-Principles Study of Elasticity and Electronic Structure of\n  Incompressible Osmium Diboride: Recently, osmium diboride (OsB2) has attracted considerable attention as an\nincompressible and hard material. We investigate the structural property,\nelastic constants, and electronic structure of orthorhombic OsB2 by the\nfirst-principles total energy calculations. The calculations are performed\nwithin the density functional framework using the projector augmented plane\nwave method. The structural properties and bulk modulus of OsB2 compare well\nwith experimental data. The nine independent elastic constants of orthorhombic\nOsB2 at zero-pressure have also been calculated by symmetry-general\nleast-squares extraction method. We have analyzed the mechanical stability of\northorhombic OsB2 in term of the calculated elastic constants. A detailed study\nof the electronic structure and the charge-density redistribution reveal the\nfeatures of strong covalent B-B and Os-B bondings in orthorhombic OsB2. The\norbital hybridization and the characteristics of bonding orbitals in OsB2 are\nidentified. Orthorhombic OsB2 exhibits a metallic character and the states at\nFermi level mainly come from the $d$ orbital of Os atoms."
    },
    {
        "anchor": "Effect of structural distortion and nature of bonding on the electronic\n  properties of defect and Li doped CulnSe2Chalcopyrite Semiconductors: We report the structural and electronic properties of chalcopyrite\nsemiconductors CuInSe2, CuIn2 Se4 and Cu0.5Li0.5InSe2. Our calculation is based\non Density functional Theory within tight binding linear muffin-tin orbital\n(TB-LMTO) method. The calculated lattice constants, anion displacement (u),\ntetragonal distortion ({\\eta} = c/2a) and bond lengths agree well with\nexperimental values. Our result shows these compounds are direct band gap\nsemiconductors. Our calculated band gaps, 0.79eV and 1.08 eV of CuInSe2 and\nCu0.5Li0.5InSe2 respectively agree well with the experimental values within the\nlimitation of LDA. The band gap of CuIn2Se4 is found to be 1.50 eV. The band\ngap reduces by 59.57%, 23.61% and 48.82% due to p-d hybridization and reduces\nby 16.85%, 9.10% and 0.92% due to structural distortion for CuInSe2, CuIn2Se4\nand Cu0.5Li0.5InSe2 respectively. We also discuss the effect of bond nature on\nelectronic properties of all three compounds.",
        "positive": "Tracking Microstructure of Crystalline Materials: A Post-Processing\n  Algorithm for Atomistic Simulations: Atomistic simulations have become a powerful tool in materials research due\nto the extremely fine spatial and temporal resolution provided by such\ntechniques. In order to understand the fundamental principles which govern\nmaterial behavior at the atomic scale and directly connect to experimental\nworks, it is necessary to quantify the microstructure of materials simulated\nwith atomistics. Specifically, quantitative tools for identifying crystallites,\ntheir crystallographic orientation, and overall sample texture do not currently\nexist. Here, we develop a post-processing algorithm capable of characterizing\nsuch features, while also documenting their evolution during a simulation. In\naddition, the data is presented in a way that parallels the visualization\nmethods used in traditional experimental techniques. The utility of this\nalgorithm is illustrated by analyzing several types of simulation cells which\nare commonly found in the atomistic modeling literature, but could also be\napplied to a variety of other atomistic studies which require precise\nidentification and tracking of microstructure."
    },
    {
        "anchor": "The excited state structure of the nitrogen-vacancy center in diamond: Optical and microwave double resonance techniques are used to obtain the\nexcited state structure of single nitrogen-vacancy centers in diamond. The\nexcited state is an orbital doublet and it is shown that it can be split and\nassociated transition strengths varied by external electric fields and by\nstrain. A group theoretical model is developed. It gives a good account of the\nobservations and contributes to an improved understanding of the electronic\nstructure of the center. The findings are important for quantum information\nprocessing and other applications of the center.",
        "positive": "Micromagnetics of rare-earth efficient permanent magnets: The development of permanent magnets containing less or no rare-earth\nelements is linked to profound knowledge of the coercivity mechanism.\nPrerequisites for a promising permanent magnet material are a high spontaneous\nmagnetization and a sufficiently high magnetic anisotropy. In addition to the\nintrinsic magnetic properties the microstructure of the magnet plays a\nsignificant role in establishing coercivity. The influence of the\nmicrostructure on coercivity, remanence, and energy density product can be\nunderstood by {using} micromagnetic simulations. With advances in computer\nhardware and numerical methods, hysteresis curves of magnets can be computed\nquickly so that the simulations can readily provide guidance for the\ndevelopment of permanent magnets. The potential of rare-earth reduced and free\npermanent magnets is investigated using micromagnetic simulations. The results\nshow excellent hard magnetic properties can be achieved in grain boundary\nengineered NdFeB, rare-earth magnets with a ThMn12 structure, Co-based\nnano-wires, and L10-FeNi provided that the magnet's microstructure is\noptimized."
    },
    {
        "anchor": "First-principles kinetic Monte Carlo simulations for heterogeneous\n  catalysis, applied to the CO oxidation at RuO2(110): We describe a first-principles statistical mechanics approach enabling us to\nsimulate the steady-state situation of heterogeneous catalysis. In a first step\ndensity-functional theory together with transition-state theory is employed to\nobtain the energetics of all relevant elementary processes. Subsequently the\nstatistical mechanics problem is solved by the kinetic Monte Carlo method,\nwhich fully accounts for the correlations, fluctuations, and spatial\ndistributions of the chemicals at the surface of the catalyst under\nsteady-state conditions. Applying this approach to the catalytic oxidation of\nCO at RuO2(110), we determine the surface atomic structure and composition in\nreactive environments ranging from ultra-high vacuum (UHV) to technologically\nrelevant conditions, i.e. up to pressures of several atmospheres and elevated\ntemperatures. We also compute the CO2 formation rates (turnover frequencies).\nThe results are in quantitative agreement with all existing experimental data.\nWe find that the high catalytic activity of this system is intimately connected\nwith a disordered, dynamic surface ``phase'' with significant compositional\nfluctuations. In this active state the catalytic function results from a\nself-regulating interplay of several elementary processes.",
        "positive": "Computational Optimization of MnBi to Enhance Energy Product: High energy density magnets are preferred over induction magnets for many\napplications, including electric motors used in flying rovers, electric\nvehicles, and wind turbines. However, several issues related to cost and supply\nwith state-of-the-art rare-earth-based magnet necessities development of\nhigh-flux magnets containing low cost, earth-abundant materials. Here, we\ndemonstrate the possibility of tuning magnetization and magnetocrystalline\nanisotropy of one of the candidate materials, MnBi, by alloying it with foreign\nelements. By using the density functional theory in the high-throughput\nfashion, we consider the possibility of alloying MnBi with all possible metal\nand non-metal elements in the periodic table and found that MnBi-based alloys\nwith Pd, Pt, Rh, Li, and O are stable against decomposition to constituent\nelements and have larger magnetization, energy product compared and magnetic\nanisotropy compared to MnBi We consider the possibility of these elements\noccupying half and all of the available empty sites. Combined with other\nfavorable properties of MnBi, such as high Curie temperature and earth\nabundancy of constituents elements, we envision the possibility of MnBi-based\nhigh-energy-density magnets."
    },
    {
        "anchor": "Investigation of the Young's modulus and thermal expansion of amorphous\n  titania-doped tantala films: The current generation of advanced gravitational wave detectors utilize\ntitania-doped tantala/silica multilayer stacks for their mirror coatings. The\nproperties of the low-refractive-index silica are well known; however, in the\nabsence of detailed direct measurements, the material parameters of Young's\nmodulus and coefficient of thermal expansion (CTE) of the high refractive index\nmaterial, titania-doped tantala, have been assumed to be equal to values\nmeasured for pure tantala coatings. In order to ascertain the true values\nnecessary for thermal noise calculations, we have undertaken measurements of\nYoung's modulus and CTE through the use of nanoindentation and thermal-bending\nmeasurements. The measurements were designed to assess the effects of titania\ndoping concentration and post-deposition heat-treatment on the measured values\nin order to evaluate the possibility of optimizing material parameters to\nfurther improve thermal noise in the detector. Young's modulus measurements on\npure tantala and 25% and 55% titania-doped tantala show a wide range of values,\nfrom 132 to 177 GPa, dependent on both titania concentration and\nheat-treatment. Measurements of CTE give values of (3.9 +/- 0.1) x 10^-6 K^-1\nand (4.9 +/- 0.3) x 10^-6 K^-1 for 25% and 55% titania-doped tantala,\nrespectively, without dependence on post-deposition heat-treatment.",
        "positive": "Anisotropic magnetic properties and tunable conductivity in\n  two-dimensional layered NaCrX2 (X=Te,Se,S) single crystals: Monolayer NaCrX2 (X=Te,Se,S) were theoretically proposed to be\ntwo-dimensional intrinsic ferromagnetic semiconductors while their physical\nproperties have not been thoroughly investigated in bulk single crystals. We\nreport the single-crystal growth, structural, magnetic and electronic transport\nproperties of NaCr(Te1-xSex)2 (0 6 x 6 1) and NaCrS2. For NaCr(Te1-xSex)2, the\nstrong perpendicular magnetic anisotropy of NaCrTe2 can be gradually tuned to\nbe a nearly isotropic one by Se-doping. Meanwhile, a systematic change in the\nconductivity with increasing x is observed, displaying a doping-induced\nmetal-insulator-like transition. Under magnetic field larger than 30 koe, both\nNaCrTe2 and NaCrSe2 can be polarized to a ferromagnetic state. While for\nNaCrS2, robust antiferromagnetism is observed up to 70 kOe and two\nfield-induced metamagnetic transitions are identified along H||ab. These\nintriguing properties together with the potential to be exfoliated down to\nfew-layer thickness make NaCrX2 (X=Te,Se,S) promising for exploring spintronic\napplications."
    },
    {
        "anchor": "QSGW calculation of the work functions of Al(111) and Al(100) surfaces: Modifications to the quasiparticle self-consistent GW (QSGW) method needed to\ncorrectly describe metal/vacuum interfaces and other systems having extended\nregions with small electron density are identified and implemented. The\nmethod's accuracy is investigated by calculating work functions for the\nAl(111), Al(100), and Al(110) surfaces. We find that the results for work\nfunction do not depend on the DFT functional employed to calculate the starting\nHamiltonian and that QSGW yield results in quantitative agreement with data\nfrom ultrahigh vacuum experiments.",
        "positive": "Tuning the intermediate reaction barriers by CuPd catalyst to improve\n  the selectivity of electroreduction CO2 to C2 products: Electrochemical CO2 reduction is a promising strategy for utilization of CO2\nand intermittent excess electricity. Cu is the only single-metal catalyst that\ncan electrochemically convert CO2 to multi-carbon products. However, Cu has an\nundesirable selectivity and activity for C2 products, due to its insufficient\namount of CO* for C-C coupling. Considering the strong CO2 adsorption and\nultra-fast reaction kinetics of CO* formation on Pd, an intimate CuPd(100)\ninterface was designed to lower the intermediate reaction barriers and then\nimprove the efficiency of C2 products. Density functional theory (DFT)\ncalculations showed that the CuPd(100) interface has enhanced CO2 adsorption\nand decreased CO2* hydrogenation energy barrier, which are beneficial for C-C\ncoupling. The potential-determining step (PDS) barrier of CO2 to C2 products on\nCuPd(100) interface is 0.61 eV, which is lower than that on Cu(100) (0.72 eV).\nMotivated by the DFT calculation, the CuPd(100) interface catalyst was prepared\nby a facile chemical solution method and demonstrated by transmission electron\nmicroscope (TEM). The CO2 temperature programmed desorption (CO2-TPD) and gas\nsensor experiments proved the enhancements of CO2 adsorption and CO2*\nhydrogenation abilities on CuPd(100) interface catalyst. As a result, the\nobtained CuPd(100) interface catalyst exhibits a C2 Faradaic efficiency of 50.3\n(+/-) 1.2% at -1.4 VRHE in 0.1 M KHCO3, which is 2.1 times higher than\n23.6(+/-) 1.5% of Cu catalyst. This work provides a rational design of Cu-based\nelectrocatalyst for multi-carbon products by fine-tuning the intermediate\nreaction barriers."
    },
    {
        "anchor": "Facet dependent surface energy gap on magnetic topological insulators: Magnetic topological insulators (MnBi$_2$Te$_4$)(Bi$_2$Te$_3$)$_n$\n($n=0,1,2,3$) are promising to realize exotic topological states such as the\nquantum anomalous Hall effect (QAHE) and axion insulator (AI), where the\nBi$_2$Te$_3$ layer introduces versatility to engineer electronic and magnetic\nproperties. However, whether surface states on the Bi$_2$Te$_3$ terminated\nfacet are gapless or gapped is debated, and its consequences in thin-film\nproperties are rarely discussed. In this work, we find that the Bi$_2$Te$_3$\nterminated facets are gapless for $n \\ge 1$ compounds by calculations. Despite\nthat the surface Bi$_2$Te$_3$ (one layer or more) and underlying MnBi$_2$Te$_4$\nlayers hybridize and give rise to a gap, such a hybridization gap overlaps with\nbulk valence bands, leading to a gapless surface after all. Such a metallic\nsurface poses a fundamental challenge to realize QAHE or AI, which requires an\ninsulating gap in thin films with at least one Bi$_2$Te$_3$ surface. In theory,\nthe insulating phase can still be realized in a film if both surfaces are\nMnBi$_2$Te$_4$ layers. Otherwise, it requires that the film thickness is less\nthan 10$\\sim$20 nm to push down bulk valence bands via the size effect. Our\nwork paves the way to understand surface states and design bulk-insulating\nquantum devices in magnetic topological materials.",
        "positive": "Using $G_0W_0$ Level Alignment to Identify Catechol's Structure on\n  TiO$_2$(110): We perform state-of-the-art calculations for a prototypical dye sensitized\nsolar cell: catechol on rutile TiO$_2$(110). Catechol is often used as an\nanchoring group for larger more complex organic and inorganic dyes on TiO$_2$\nand forms a type II heterojunctions on TiO$_2$(110). In particular, we compare\nquasiparticle (QP) $G_0W_0$ with hybrid exchange correlation functional (HSE)\ndensity functional theory (DFT) calculations for the catechol-rutile\nTiO$_2$(110) interface. In so doing, we provide a theoretical interpretation of\nultraviolet photoemission spectroscopy (UPS) and inverse photoemission\nspectroscopy (IPES) experiments for this prototypical system. Specifically, we\ndemonstrate that the position, presence, and intensity of peaks associated with\ncatechol's HOMO, intermolecular OH$-$O bonds, and interfacial hydrogen bonds to\nthe surface bridging O atoms (O$_{br}$H$-$C and O$_{br}$H$-$O) may be used to\nfingerprint deprotonation of catechol's OH anchoring groups. Furthermore, our\nresults suggest deprotonation of these groups, while being nearly isoenergetic\nat high coverages, may significantly increase the photovoltaic efficiency of\ncatechol$-$TiO$_2$(110) interfaces."
    },
    {
        "anchor": "A hunt for ultrahard materials: Recent results on search (theoretical prediction, high-pressure synthesis,\netc.) for novel superhard and ultrahard materials are briefly reviewed.",
        "positive": "Resistive switching of tetraindolyl derivative in ultrathin films: A\n  potential candidate for non-volatile memory applications: Bipolar resistive switching using organic molecule is very promising for\nmemory application owing to their advantages like simple device structure, low\nmanufacturing cost, their stability and flexibility etc. Herein we report\nLangmuir-Blodgett and spin-coated film based bipolar resistive switching\ndevices using organic material indole derivative. Pressure - area per molecule\nisotherm, Brewster Angle Microscopy, Atomic Force Microscopy and Scanning\nElectron Microscopy were used to have an idea about organization and morphology\nof the organic material onto thin film. Based on device structure and\nmeasurement protocol it is observed that the device made up of 1 shows\nnon-volatile Resistive Random Access Memory behaviour with very high memory\nwindow, data sustainability and repeatability.Oxidation-reduction process as\nwell as electric field driven conduction are the key behind such switching\nbehaviour.Due to very good data retention, repeatability, stability and high\ndevice yield the switching device designed using compound 1may be a potential\ncandidate for memory applications."
    },
    {
        "anchor": "Fully strained epitaxial Ti_{1-x}Mg_xN(001) layers: Ti1-xMgxN(001) layers with 0.00 {\\leq} x {\\leq} 0.49 are deposited on\nMgO(001) by reactive magnetron co-sputtering from titanium and magnesium\ntargets in 5 mTorr pure N2 at 600 {\\deg}C. X-ray diffraction {\\omega}-2{\\theta}\nscans, {\\omega}-rocking curves, {\\phi}-scans, and high resolution reciprocal\nspace maps show that the Ti1-xMgxN layers are rock-salt structure single\ncrystals with a cube-on-cube epitaxial relationship with the substrates:\n(001)TiMgN{\\parallel} (001)MgO and [100]TiMgN{\\parallel} [100]MgO. Layers with\nthickness d = 35-58 nm are fully strained, with an in-plane lattice parameter\nof 4.212{\\pm}0.001 {\\AA} matching that of the MgO substrate, while the\nout-of-plane lattice parameter increases with x from 4.251 {\\AA} for TiN(001)\nto 4.289 {\\AA} for Ti0.51Mg0.49N(001). This yields a relaxed lattice parameter\nfor Ti1-xMgxN(001) of ao = (1-x)aTiN + xaMgN - bx(1-x), where aTiN = 4.239\n{\\AA}, aMgN = 4.345 {\\AA}, and the bowing parameter b = 0.113 {\\AA}. In\ncontrast, thicker Ti1-xMgxN(001) layers with d = 110-275 nm are partially (pure\nTiN) or fully (x = 0.37 and 0.39) relaxed, indicating a critical thickness for\nrelaxation of 50-100 nm. The in-plane x-ray coherence length is large (100-400\nnm) for fully strained layers with 0.00 {\\leq} x {\\leq} 0.45 but drops by an\norder of magnitude for x = 0.49 as the composition approaches the phase\nstability limit. It is also an order of magnitude smaller for thicker (d {\\leq}\n110 nm) layers, which is attributed to strain relaxation through the nucleation\nand growth of misfit dislocations facilitated by glide of threading\ndislocations.",
        "positive": "Strain distribution in polycrystals: Theory and Application for\n  Diffraction Experiments: Randomly textured polycrystalline materials of constituents with highly\nanisotropic nature of grains can be considered globally isotropic. In order to\ndetermine the isotropic properties, like elasticity or conductivity, we propose\na theory for averaging the coefficients of the corresponding tensors unifying\nVoigt's, Reuss' or other self-consistent homogenization theories. We apply the\nmethod to determine elastic moduli of untextured polycrystals with arbitrary\ncrystal structures, recovering experimental data with high precision for cubic\nmaterials. We show that the average moduli can be used to predict analytically\nstress and strain states inside individual grains as proven by the comparison\nwith neutron diffraction measurements. Finally, we discuss a few possible\ngeneralizations for textured materials for further applications."
    },
    {
        "anchor": "Bottom up synthesis of multifunctional nanoporous graphene: Nanosize pores can turn semimetallic graphene into a semiconductor and from\nbeing impermeable into the most efficient molecular sieve membrane. However,\nscaling the pores down to the nanometer, while fulfilling the tight structural\nconstraints imposed by applications, represents an enormous challenge for\npresent top-down strategies. Here we report a bottom-up method to synthesize\nnanoporous graphene comprising an ordered array of pores separated by ribbons,\nwhich can be tuned down to the one nanometer range. The size, density,\nmorphology and chemical composition of the pores are defined with atomic\nprecision by the design of the molecular precursors. Our measurements further\nreveal a highly anisotropic electronic structure, where orthogonal\none-dimensional electronic bands with an energy gap of ~1 eV coexist with\nconfined pore states, making the nanoporous graphene a highly versatile\nsemiconductor for simultaneous sieving and electrical sensing of molecular\nspecies.",
        "positive": "The Efficacy of Fiction or More on the Charge State of Ti in TiO2 and\n  Formal Oxidation States: We argue that Ti4+ is not a realistic description of Ti in TiO2."
    },
    {
        "anchor": "The Best Nanoparticle Size Distribution for Minimum Thermal Conductivity: Which sizes of nanoparticles embedded in a crystalline solid yield the lowest\nthermal conductivity? Nanoparticles have long been demonstrated to reduce the\nthermal conductivity of crystals by scattering phonons, but most previous works\nassumed the nanoparticles to have a single size. Here, we use optimization\nmethods to show that the best nanoparticle size distribution to scatter the\nbroad thermal phonon spectrum is not a similarly broad distribution but rather\nseveral discrete peaks at well-chosen nanoparticle radii. For SiGe, the best\nsize distribution yields a thermal conductivity below that of amorphous\nsilicon. Further, we demonstrate that a simplified distribution yields nearly\nthe same low thermal conductivity and can be readily fabricated. Our work\nprovides important insights into how to manipulate the full spectrum of phonons\nand will guide the design of more efficient thermoelectric materials.",
        "positive": "Transferable empirical pseudopotenials from machine learning: Machine learning is used to generate empirical pseudopotentials that\ncharacterize the local screened interactions in the Kohn-Sham Hamiltonian. Our\napproach incorporates momentum-range-separated rotation-covariant descriptors\nto capture crystal symmetries as well as crucial directional information of\nbonds, thus realizing accurate descriptions of anisotropic solids. Trained\nempirical potentials are shown to be versatile and transferable such that the\ncalculated energy bands and wave functions without cumbersome self-consistency\nreproduce conventional ab initio results even for semiconductors with defects,\nthus fostering faster and faithful data-driven materials researches."
    },
    {
        "anchor": "Epitaxial Growth and Domain Structure Imaging of Kagome Magnet\n  Fe$_3$Sn$_2$: Magnetic materials with kagome crystal structure exhibit rich physics such as\nfrustrated magnetism, skyrmion formation, topological flat bands, and\nDirac/Weyl points. Until recently, most studies on kagome magnets have been\nperformed on bulk crystals or polycrystalline films. Here we report the\nsynthesis of high-quality epitaxial films of topological kagome magnet\nFe$_3$Sn$_2$ by atomic layer molecular beam epitaxy. Structural and magnetic\ncharacterization of Fe$_3$Sn$_2$ on epitaxial Pt(111) identifies highly ordered\nfilms with c-plane orientation and an in-plane magnetic easy axis. Studies of\nthe local magnetic structure by anomalous Nernst effect imaging reveals\nin-plane oriented micrometer size domains. The realization of high-quality\nfilms by atomic layer molecular beam epitaxy opens the door to explore the rich\nphysics of this system and investigate novel spintronic phenomena by\ninterfacing Fe$_3$Sn$_2$ with other materials.",
        "positive": "Extraordinary strain hardening from dislocation loops in defect-free Al\n  nanocubes: The interaction of crystalline defects leads to strain hardening in bulk\nmetals. Metals with high stacking fault energy (SFE), such as aluminum, tend to\nhave low strain hardening rates due to an inability to form stacking faults and\ndeformation twins. Here, we use in situ SEM mechanical compressions to find\nthat colloidally synthesized defect-free 114 nm Al nanocubes combine a high\nlinear strain hardening rate of 4.1 GPa with a high strength of 1.1 GPa. These\nnanocubes have a 3 nm self-passivating oxide layer that has a large influence\non mechanical behavior and the accumulation of dislocation structures.\nPost-compression TEM imaging reveals stable prismatic dislocation loops and the\nabsence of stacking faults. MD simulations relate the formation of dislocation\nloops and strain hardening to the surface oxide. These results indicate that\nslight modifications to surface and interfacial properties can induce enormous\nchanges to mechanical properties in high SFE metals."
    },
    {
        "anchor": "Field free switching through bulk spin-orbit torque in L10-FePt films\n  deposited on vicinal substrates: L10-FePt distinguishes itself for its ultrahigh perpendicular magnetic\nanisotropy (PMA), which enables memory cells with sufficient thermal stability\nto scale down to 3 nm. The recently discovered \"bulk\" spin-orbit torques in\nL10-FePt provide an efficient and scalable way to manipulate the L10-FePt\nmagnetization. However, the existence of external field during the switching\nlimits its practical application, and therefore field-free switching of the\nL10-FePt is in highly demand. In this manuscript, we demonstrate the field-free\nswitching of the L10-FePt by growing it on vicinal MgO (001) substrates. This\nmethod is different from previously established strategies, as it does not need\nto add other functional layers or create asymmetry in the film structure. We\ndemonstrate the field-free switching is robust and can withstand strong field\ndisturbance up to ~1 kOe. The dependence on vicinal angle, film thickness, and\ngrowth temperature demonstrated a wide operation window for the field-free\nswitching of the L10-FePt. We confirmed that the physical origin of the\nfield-free switching is the vicinal surface-induced the tilted anisotropy of\nL10-FePt. We quantitatively characterize the spin-orbit torques in the L10-FePt\nfilms, and found the spin-orbit torques are not significantly influenced by the\nlattice strain from vicinal substrates. Our results extend beyond the\nestablished strategies to realize field-free switching, and potentially could\nbe applied to other magnetic and antiferromagnetic systems.",
        "positive": "Kinetics of segregation formation in the vicinity of edge dislocation in\n  fcc metals: We use new equations for the interstitial impurity diffusion fluxes under\nstrain to study impurity atom redistribution in the vicinity of dislocations.\nTwo levels of simulation are applied. The first one is evaluation of\ncoefficients that determine the influence of strain tensor components on\ninterstitial diffusion fluxes in FCC structures. For this purpose we have\ndeveloped a model into the framework of a molecular static method taking into\naccount an atom environment both near the interstitial site and for the\nsaddle-point configuration. The second level is modeling the interstitial\nsegregation formation based on nonlinear diffusion equations that take strains\ngenerated by defects into account. The results show that the distributions of\nthe interstitials near the dislocations have quite complicated characters and\nthe vacancy distribution has a qualitatively different character as compared\nwith the carbon distribution."
    },
    {
        "anchor": "Primitive to conventional geometry projection for efficient phonon\n  transport calculations: The primitive Wigner-Seitz cell and corresponding first Brillouin zone (FBZ)\nare typically used in calculations of lattice vibrational and transport\nproperties as they contain the smallest number of degrees of freedom and thus\nhave the cheapest computational cost. However, in complex materials, the FBZ\ncan take on irregular shapes where lattice symmetries are not apparent. Thus,\nconventional cells (with more atoms and regular shapes) are often used to\ndescribe materials, though dynamical and transport calculations are more\nexpensive. Here we discuss an efficient anharmonic lattice dynamic method that\nmaps conventional cell dynamics to primitive cell dynamics based on\ntranslational symmetries. This leads to phase interference conditions that act\nlike conserved quantum numbers and a conservation rule for phonon scattering\nthat is hidden in conventional dynamics which significantly reduces\ncomputational cost. We demonstrate this method for phonon transport in a\nvariety of materials with inputs from first-principles calculations and\nattribute its efficiency to reduced scattering phase space and fewer summations\nin scattering matrix element calculations.",
        "positive": "Machine-Learning-Assisted Construction of Ternary Convex Hull Diagrams: In the search for novel intermetallic ternary alloys, much of the effort goes\ninto performing a large number of ab-initio calculations covering a wide range\nof compositions and structures. These are essential to build a reliable convex\nhull diagram. While density functional theory (DFT) provides accurate\npredictions for many systems, its computational overheads set a throughput\nlimit on the number of hypothetical phases that can be probed. Here, we\ndemonstrate how an ensemble of machine-learning spectral neighbor-analysis\npotentials (SNAPs) can be integrated into a workflow for the construction of\naccurate ternary convex hull diagrams, highlighting regions fertile for\nmaterials discovery. Our workflow relies on using available binary-alloy data\nboth to train the SNAP models and to create prototypes for ternary phases. From\nthe prototype structures, all unique ternary decorations are created and used\nto form a pool of candidate compounds. The SNAPs are then used to pre-relax the\nstructures and screen the most favourable prototypes, before using DFT to build\nthe final phase diagram. As constructed, the proposed workflow relies on no\nextra first-principles data to train the machine-learning surrogate model and\nyields a DFT-level accurate convex hull. We demonstrate its efficacy by\ninvestigating the Cu-Ag-Au and Mo-Ta-W ternary systems."
    },
    {
        "anchor": "Carrier-Density Control of the Quantum-Confined 1$T$-TiSe$_2$\n  Charge-Density-Wave: Using angle-resolved photoemission spectroscopy, combined with first\nprinciple and coupled self-consistent Poisson-Schr\\\"odinger calculations, we\ndemonstrate that potassium (K) atoms adsorbed on the low-temperature phase of\n1$T$-TiSe$_2$ induce the creation of a two-dimensional electron gas (2DEG) and\nquantum confinement of its charge-density-wave (CDW) at the surface. By further\nchanging the K coverage, we tune the carrier-density within the 2DEG that\nallows us to nullify, at the surface, the electronic energy gain due to exciton\ncondensation in the CDW phase while preserving a long-range structural order.\nOur study constitutes a prime example of a controlled exciton-related many-body\nquantum state in reduced dimensionality by alkali-metal dosing.",
        "positive": "Calculating linear response functions for finite temperatures on the\n  basis of the alloy analogy model: A scheme is presented that is based on the alloy analogy model and allows to\naccount for thermal lattice vibrations as well as spin fluctuations when\ncalculating response quantities in solids. Various models to deal with spin\nfluctuations are discussed concerning their impact on the resulting temperature\ndependent magnetic moment, longitudinal conductivity and Gilbert damping\nparameter. It is demonstrated that using the Monte Carlo (MC) spin\nconfiguration as an input, the alloy analogy model is capable to reproduce\nresults of MC simulations on the average magnetic moment within all spin\nfluctuation models under discussion. On the other hand, response quantities are\nmuch more sensitive to the spin fluctuation model. Separate calculations\naccounting for either the thermal effect due to lattice vibrations or spin\nfluctuations show their comparable contributions to the electrical conductivity\nand Gilbert damping. However, comparison to results accounting for both thermal\neffects demonstrate violation of Matthiessen's rule, showing the non-additive\neffect of lattice vibrations and spin fluctuations. The results obtained for\nbcc Fe and fcc Ni are compared with the experimental data, showing rather good\nagreement for the temperature dependent electrical conductivity and Gilbert\ndamping parameter."
    },
    {
        "anchor": "Influence of anti-site disorder and electron-electron correlations on\n  the electronic structure of CeMnNi$_4$: CeMnNi$_4$ exhibits an unusually large spin polarization, but its origin has\nbaffled researchers for more than a decade. We use bulk sensitive hard x-ray\nphotoelectron spectroscopy (HAXPES) and density functional theory based on the\nGreen's function technique to demonstrate the importance of electron-electron\ncorrelations of both the Ni 3$d$ ($U_{Ni}$) and Mn 3$d$ ($U_{Mn}$) electrons in\nexplaining the valence band of this multiply correlated material. We show that\nMn-Ni anti-site disorder as well as $U_{Ni}$ play crucial role in enhancing its\nspin polarization: anti-site disorder broadens a Ni 3$d$ minority-spin peak\nclose to the Fermi level ($E_F$), while an increase in $U_{Ni}$ shifts it\ntowards $E_F$, both leading to a significant increase of minority-spin states\nat $E_F$. Furthermore, rare occurrence of a valence state transition between\nthe bulk and the surface is demonstrated highlighting the importance of HAXPES\nin resolving the electronic structure of materials unhindered by surface\neffects.",
        "positive": "First-principles investigation of interfacial reconstruction in\n  epitaxial SrTiO$_3$/Si photocathodes: Epitaxial SrTiO$_3$ (STO) on Si is nowadays the benchmark initial platform\nfor the further addition of functional oxides on Si. Starting the growth of STO\non a Sr-passivated Si substrate with 1/2 monolayer (ML) Sr coverage and a (1\n$\\times$ 2) reconstructed Si surface with rows of Si dimers, the final\nSTO/Sr/Si stack exhibits 1 ML Sr coverage and a (1 $\\times$ 1) Si surface\nwithout dimer. Using first-principles density functional theory calculations,\nwe investigate how the interface evolves from 1/2 ML to 1 ML Sr coverage,\nconcluding that the latter is indeed most stable and that the reconstruction of\nthe interface takes place during the early stage of the layer-by-layer\ndeposition. Going further, we determine the band alignment of the final stable\ninterface and assess its potential interest as photocathode for water\nreduction."
    },
    {
        "anchor": "Van der Waals pressure and its effect on trapped interlayer molecules: Van der Waals assembly of two-dimensional (2D) crystals continue attract\nintense interest due to the prospect of designing novel materials with\non-demand properties. One of the unique features of this technology is the\npossibility of trapping molecules or compounds between 2D crystals. The trapped\nmolecules are predicted to experience pressures as high as 1 GPa. Here we\nreport measurements of this interfacial pressure by capturing\npressure-sensitive molecules and studying their structural and conformational\nchanges. Pressures of 1.2 +/- 0.3 GPa are found using Raman spectrometry for\nmolecular layers of one nanometer in thickness. We further show that this\npressure can induce chemical reactions and several trapped salts or compounds\nare found to react with water at room temperature, leading to 2D crystals of\nthe corresponding oxides. This pressure and its effect should be taken into\naccount in studies of van der Waals heterostructures and can also be exploited\nto modify materials confined at the atomic interfaces.",
        "positive": "Synthesis and characterization of vertically oriented hybrid Zn2GeO4-ZnO\n  beaded nanowire arrays and Zn2GeO4 nanotubes: Vertically aligned, beaded zinc germinate (Zn2GeO4)/ zinc oxide (ZnO) hybrid\nnanowire arrays were successfully synthesized by a vapor-solid process via a\ncatalyst-free approach. The as-synthesized products were characterized using\nX-ray diffraction, scanning electron microscopy and transmission electron\nmicroscopy equipped with an energy-dispersive X-ray spectrometer. TEM studies\nrevealed the beaded microstructures of the Zn2GeO4/ZnO nanowire. Furthermore,\nZn2GeO4 nanotubes were synthesized after wet etching treatments on Zn2GeO4/ZnO\nhybrid nanowires."
    },
    {
        "anchor": "Characterization of Defect Structure in Electrodeposited Nanocrystalline\n  Ni Films: The microstructure of electrodeposited Ni films produced without and with\norganic additives (saccharin and formic acid) was investigated by X-ray\ndiffraction (XRD) line profile analysis and cross-sectional transmission\nelectron microscopy (TEM). Whereas the general effect of these additives on the\nmicrostructure (elimination of columnar growth as well as grain refinement) was\nreproduced, the pronounced intention of this study was to compare the results\nof various seldom-used high-performance structural characterization methods on\nidentical electrodeposited specimens in order to reveal fine details of\nstructural changes qualitatively not very common in this field. In the film\ndeposited without additives, a columnar structure was observed showing\nsimilarities to the T-zone of structure zone models. Both formic acid and\nsaccharin additives resulted in equiaxed grains with reduced size, as well as\nincreased dislocation and twin fault densities in the nanocrystalline films.\nMoreover, the structure became homogeneous and free of texture within the total\nfilm thickness due to the additives. Saccharin yielded smaller grain size and\nlarger defect density than formic acid. A detailed analysis of the grain size\nand twin boundary spacing distributions was carried out with the complementary\napplication of TEM and XRD, by carefully distinguishing between the TEM and XRD\ngrain sizes.",
        "positive": "Theoretical prediction of Curie temperature in two-dimensional\n  ferromagnetic monolayer: Theoretical prediction of Curie temperature (TC) is of vital importance for\ndesigning the spintronic devices in two-dimensional (2D) ferromagnetic\nmaterials. Herein, based on the extensive investigation of Monte Carlo\nsimulations, we summary and propose an improved method to estimate TC more\nprecisely, which includes the different contributions of multiple near-neighbor\ninteractions. Taking monolayer CrI3 as an example, the trends of TC with\nbiaxial strain are investigated via Monte Carlo simulations, mean-field\nformulas and our method. Besides, our method is not only accurate and\nconvenient to predicting the TC in 2D ferromagnetic honeycomb lattice CrI3 but\nit can be extended for predicting the TC of other 2D lattices. Our work paves\nthe way to accelerate the prediction and discovery of novel 2D ferromagnets for\nspintronic applications."
    },
    {
        "anchor": "Thermographic measurements of the spin Peltier effect in\n  metal/yttrium-iron-garnet junction systems: The spin Peltier effect (SPE), heat-current generation due to spin-current\ninjection, in various metal (Pt, W, and Au single layers and Pt/Cu\nbilayer)/ferrimagnetic insulator (yttrium iron garnet: YIG) junction systems\nhas been investigated by means of a lock-in thermography (LIT) method. The SPE\nis excited by a spin current across the metal/YIG interface, which is generated\nby applying a charge current to the metallic layer via the spin Hall effect.\nThe LIT method enables the thermal imaging of the SPE free from the\nJoule-heating contribution. Importantly, we observed spin-current-induced\ntemperature modulation not only in the Pt/YIG and W/YIG systems but also in the\nAu/YIG and Pt/Cu/YIG systems, excluding the possible contamination by anomalous\nEttingshausen effects due to proximity-induced ferromagnetism near the\nmetal/YIG interface. As demonstrated in our previous study, the SPE signals are\nconfined only in the vicinity of the metal/YIG interface; we buttress this\nconclusion by reducing a spatial blur due to thermal diffusion in an infrared\nemission layer on the sample surface used for the LIT measurements. We also\nfound that the YIG-thickness dependence of the SPE is similar to that of the\nspin Seebeck effect measured in the same Pt/YIG sample, implying the reciprocal\nrelation between them.",
        "positive": "Disordered Hyperuniform Solid State Materials: Disordered hyperuniform (DHU) states are recently discovered exotic states of\ncondensed matter. DHU systems are similar to liquids or glasses in that they\nare statistically isotropic and lack conventional long-range translational and\norientational order. On the other hand, they completely suppress normalized\ninfinite-wavelength density fluctuations like crystals, and in this sense\npossess a hidden long-range order. Very recently, there are several exciting\ndiscoveries of disordered hyperuniformity in solid-state materials, including\namorphous carbon nanotubes, amorphous 2D silica, amorphous graphene, defected\ntransition metal dichalcogenides, defected pentagonal 2D materials, and\nmedium/high-entropy alloys. It has been found the DHU states of these materials\noften possess a significantly lower energy than other disorder models, and can\nlead to unique electronic and thermal transport properties, which resulted from\nmechanisms distinct from those identified for their crystalline counterparts.\nFor example, DHU states can enhance electronic transport in 2D amorphous\nsilica; DHU medium/high-entropy alloys realize the Vegard's law, and possess\nenhanced electronic band gaps and thermal transport at low temperatures. These\nunique properties open up many promising potential device applications in\noptoelectronics and thermoelectrics. Here, we provide a focused review on these\nimportant new developments of hyperuniformity in solid-state materials, taking\nan applied and ``materials'' perspective, which complements the existing\nreviews on hyperuniformity in physical systems and photonic materials. Future\ndirections and outlook are also provided, with a focus on the design and\ndiscovery of DHU quantum materials for quantum information science and\nengineering."
    },
    {
        "anchor": "Effects of physical and chemical pressure on charge density wave\n  transitions in LaAg1-xAuxSb2 single crystals: The structural characterization and electrical transport measurements at\nambient and applied pressures of the compounds of the La(Ag1-xAux)Sb2 family\nare presented. Up to two charge density wave (CDW) transitions could be\ndetected upon cooling from room temperature and an equivalence of the effects\nof chemical and physical pressure on the CDW ordering temperatures was observed\nwith the unit cell volume being a salient structural parameter. As such\nLa(Ag1-xAux)Sb2 is a rare example of a non-cubic system that exhibits good\nagreement between the effects of applied, physical, pressure and changes in\nunit cell volume from steric changes induced by isovalent substitution.\nAdditionally, for La(Ag0.54Au0.46)Sb2 anomalies in low temperature electrical\ntransport were observed in the pressure range where the lower charge density\nwave is completely suppressed.",
        "positive": "Diffusion properties of electrons in GaN crystals subjected to electric\n  and magnetic fields: We studied the diffusion coefficient of hot electrons of GaN crystals in\nmoderate electric (1...10 kV/cm) and magnetic (1...4 T) fields. Two\nconfigurations, parallel and crossed fields, are analysed. The study was\ncarried out for compensated bulk-like GaN samples at different lattice\ntemperatures (30...300 K) and impurity concentrations (10^16..10^17 cm^{-3}).\nWe found that at low lattice temperatures and low impurity concentrations,\nelectric-field dependencies of the transverse-to-current components of the\ndiffusion tensor are non-monotonic for both configurations, while the diffusion\nprocesses are greatly controlled by the magnetic field. With an increase of the\nlattice temperature or the impurity concentration, the behaviour of the\ndiffusion tensor becomes more monotonous and less affected by the magnetic\nfield. We showed that such behaviour of the diffusion processes is due to the\ndistinct kinetics of the hot electrons in polar semiconductors with strong\nelectron-optical phonon coupling. We suggest that measurements of the diffusion\ncoefficient of the electrons subjected to electric and magnetic fields\nfacilitate the identification of features of different electron transport\nregimes and the development of more efficient devices and practical\napplications."
    },
    {
        "anchor": "Precise calibration of Mg concentration in MgxZn1-xO thin films grown on\n  ZnO substrates: The growth techniques for MgxZn1-xO thin films have advanced at a rapid pace\nin recent years, enabling the application of this material to a wide range of\noptical and electrical applications. In designing structures and optimizing\ndevice performances, it is crucial that the Mg content of the alloy be\ncontrollable and precisely determined. In this study, we have established\nlaboratory-based methods to determine the Mg content of MgxZn1-xO thin films\ngrown on ZnO substrates, ranging from the solubility limit of x ~ 0.4 to the\ndilute limit of x < 0.01. For the absolute determination of Mg content,\nRutherford backscattering spectroscopy is used for the high Mg region above x =\n0.14, while secondary ion mass spectroscopy is employed to quantify low Mg\ncontent. As a lab-based method to determine the Mg content, c-axis length is\nmeasured by X-ray diffraction and is well associated with Mg content. The\ninterpolation enables the determination of Mg content to x = 0.023, where the\npeak from the ZnO substrate overlaps the MgxZn1-xO peak in standard laboratory\nequipment, and thus quantitative determination. At dilute Mg contents below x =\n0.023, the localized exciton peak energy of the MgxZn1-xO films as measured by\nphotoluminescence is found to show a linear Mg content dependence, which is\nwell resolved from the free exciton peak of ZnO substrate down to x = 0.0043.\nOur results demonstrate that X-ray diffraction and photoluminescence in\ncombination are appropriate methods to determine Mg content in a wide Mg range\nfrom x = 0.004 to 0.40 in a laboratory environment.",
        "positive": "Structure and Properties of Epitaxial Thin Films of Bi2fecro6: A\n  Multiferroic Material Postulated by Ab-Initio Computation: Experimental results on Bi2FeCrO6 (BFCO) epitaxial films deposited by laser\nablation on SrTiO3 substrates are presented. It has been theoretically\npredicted using first-principles density functional theory that BFCO is\nferrimagnetic (with a magnetic moment of 2muB per formula unit) and\nferroelectric (with a polarization of ~80 microC/cm2 at 0K). The crystal\nstructure investigated using X-ray diffraction shows that the films are\nepitaxial with a high degree of crystallinity. Chemical analysis carried out by\nX-ray Microanalysis and X-ray Photoelectron Spectroscopy indicates the correct\ncationic stoichiometry in the BFCO layer, namely (Bi:Fe:Cr = 2:1:1).\nCross-section high-resolution transmission electron microscopy images together\nwith selected area electron diffraction confirm the crystalline quality of the\nepitaxial BFCO films with no identifiable foreign phase or inclusion. The\nmultiferroic character of BFCO is proven by piezoresponse force microscopy\n(PFM) and magnetic measurements showing that the films exhibit ferroelectric\nand magnetic hysteresis at room temperature. The local piezoelectric\nmeasurements show the presence of ferroelectric domains and their switching at\nthe sub-micron scale."
    },
    {
        "anchor": "Synthesis parameter effect detection using quantitative representations\n  and high dimensional distribution distances: Detection of effects of the parameters of the synthetic process on the\nmicrostructure of materials is an important, yet elusive goal of materials\nscience. We develop a method for detecting effects based on copula theory, high\ndimensional distribution distances, and permutational statistics to analyze a\ndesigned experiment synthesizing plutonium oxide from Pu(III) Oxalate. We\ndetect effects of strike order and oxalic acid feed on the microstructure of\nthe resulting plutonium oxide, which match the literature well. We also detect\nexcess bivariate effects between the pairs of acid concentration, strike order\nand precipitation temperature.",
        "positive": "Biferroic YCrO3: YCrO3 which has a monoclinic structure, shows weak ferromagnetism below 140 K\n(TN) and a ferroelectric transition at 473 K accompanied by hysteresis. We have\ndetermined the structure and energetics of YCrO3 with ferromagnetic and\nantiferromagnetic ordering by means of first-principles density functional\ntheory calculations, based on pseudopotentials and a plane wave basis. The\nnon-centrosymmetric monoclinic structure is found to be lower in energy than\nthe orthorhombic structure, supporting the biferroic nature of YCrO3."
    },
    {
        "anchor": "Random packing of spheres in Menger sponge: Random packing of spheres inside fractal collectors of dimension 2 < d < 3 is\nstudied numerically using Random Sequential Adsorption (RSA) algorithm. The\npaper focuses mainly on the measurement of random packing saturation limit.\nAdditionally, scaling properties of density autocorrelations in the obtained\npacking are analyzed. The RSA kinetics coefficients are also measured. Obtained\nresults allow to test phenomenological relation between random packing\nsaturation density and collector dimension. Additionally, performed simulations\ntogether with previously obtained results confirm that, in general, the known\ndimensional relations are obeyed by systems having non-integer dimension, at\nleast for d < 3.",
        "positive": "Controlling phase transition in monolayer metal diiodides XI$_{2}$ (X:\n  Fe, Co, and Ni) by carrier doping: We applied the generalized Bloch theorem to verify the ground state (most\nstable state) in monolayer metal diiodides 1T-XI$_{2}$ (X: Fe, Co, and Ni), a\nfamily of metal dihalides, using the first-principles calculations. The ground\nstate, which can be ferromagnetic, antiferromagnetic, or spiral state, was\nspecified by a wavevector in the primitive unit cell. While the ground state of\nFeI$_{2}$ is ferromagnetic, the spiral state becomes the ground state for\nCoI$_{2}$ and NiI$_{2}$. Since the multiferroic behavior in the metal dihalide\ncan be preserved by the spiral structure, we believe that CoI$_{2}$ and\nNiI$_{2}$ are promising multiferroic materials in the most stable state. When\nthe lattice parameter increases, we also show that the ground state of\nNiI$_{2}$ changes to a ferromagnetic state while others still keep their\ninitial ground states. For the last discussion, we revealed the phase\ntransition manipulated by hole-electron doping due to the spin-spin competition\nbetween the ferromagnetic superexchange and the antiferromagnetic direct\nexchange. These results convince us that metal diiodides have many benefits for\nfuture spintronic devices."
    },
    {
        "anchor": "Statistical approach to flow stress and generalized Hall-Petch law for\n  equilibrium polycrystalline materials: A theory of flow stress, including the yield strength is proposed for the\nclass of PC materials with equilibrium defect structure (EDS), which is\nestablished in the PC material after series of $N_0$ similar treatments of\nsevere plastic deformation at fixed temperature T and characterized by\nstabilized scalar dislocation density (SDD) and average grain size d. We\ncalculate both the stationary SDD $\\rho(b,d,T)$ and suggest a way to calculate\n$\\varepsilon$-evolution of an equilibrium SDD $\\rho_{\\varepsilon}$ in PC sample\nunder quasy-static loading depending on the average size $d$ of a grain in the\nrange of $10^{-8}- 10^{-2}$ m, on grain boundaries orientation. The analytical\ndependence is realized within a disclination-dislocation mechanism in\napproximation of single dislocation ensemble for given phase and T. It is based\non a statistical model of Boltzmann-like distribution (smoothly dependent on a\nstrain ${\\varepsilon}$) for discrete energy spectrum in each grain of a\nsingle-mode one-phase PC material with respect to quasi-stationary levels under\nplastic loading with the highest level equal to the energy of dislocation with\nmaximal length. The difference of equilibrium SDD, $\\rho_{\\varepsilon}- \\rho$,\nleads to a flow stress from the Taylor strain hardening mechanism containing\n(for $\\varepsilon$ = $0.002$) the normal and anomalous Hall-Petch relations for\ncoarse and nanocrystalline grains, respectively, and gains a maximum at floe\nstress values for an extreme size containing $d_0$ of order $10^{-8}- 10^{-7}$\nm. The maximum undergoes a shift to the region of larger grains for decreasing\ntemperatures, revealing temperature-dimension effect. Coincidence is well\nestablished between the theoretical and experimental data on ${\\sigma}_y$ for\nthe materials with EDS with BCC (${\\alpha}$-Fe), FCC (Cu, Al, Ni) and HCP\n(${\\alpha}$-Ti, Zr) crystal lattices with closely packed grains at T=300K.",
        "positive": "Parallel Stitching of Two-Dimensional Materials: Diverse parallel stitched two-dimensional heterostructures are synthesized,\nincluding metal-semiconductor (graphene-MoS2), semiconductor-semiconductor\n(WS2-MoS2), and insulator-semiconductor (hBN-MoS2), directly through selective\nsowing of aromatic molecules as the seeds in chemical vapor deposition (CVD)\nmethod. Our methodology enables the large-scale fabrication of lateral\nheterostructures with arbitrary patterns, and clean and precisely aligned\ninterfaces, which offers tremendous potential for its application in integrated\ncircuits."
    },
    {
        "anchor": "Linear response theories for interatomic exchange interactions: In 1987, Liechtenstein et al. came up with the idea to formulate the problem\nof interatomic exchange interactions, which would describe the energy change\ncaused by the infinitesimal rotations of spins, in terms of the magnetic\nsusceptibility. The formulation appears to be very generic and, for isotropic\nsystems, expresses the energy change in the form of the Heisenberg model,\nirrespectively on which microscopic mechanism stands behind the interaction\nparameters. Moreover, this approach establishes the relationship between the\nexchange interactions and the electronic structure obtained, for instance, in\nthe first-principles calculations based on the density functional theory. The\npurpose of this review is to elaborate basic ideas of the linear response\ntheories for the exchange interactions as well as more recent developments. The\nspecial attention is paid to the approximations underlying the original method\nof Liechtenstein et al. in comparison with its more recent and more rigorous\nextensions, the roles of the on-site Coulomb interactions and the ligand\nstates, and calculations of antisymmetric Dzyaloshinskii-Moriya interactions,\nwhich can be performed alongside with the isotropic exchange, within one\ncomputational scheme. The abilities of the linear response theories as well as\nmany theoretical nuances, which may arise in the analysis of interatomic\nexchange interactions, are illustrated on magnetic van der Walls materials\nCr$X_3$ ($X$$=$ Cl, I), half-metallic ferromagnet CrO$_2$, ferromagnetic Weyl\nsemimetal Co$_3$Sn$_2$S$_2$, and orthorhombic manganites $A$MnO$_3$ ($A$$=$ La,\nHo), known for the peculiar interplay of the lattice distortion, spin, and\norbital ordering.",
        "positive": "Cycloidal magnetism driven ferroelectricity in double tungstate\n  LiFe(WO$_4$)$_2$: Tungstates $A$WO$_4$ with the wolframite structure characterized by the\n$A$O$_6$ octahedral zigzag chains along the $c$-axis, can be magnetic if\n$A$=Mn, Fe, Co, Cu, Ni. Among them, MnWO$_4$ is a unique member with a cycloid\nMn$^{2+}$ spin order developed at low temperature, leading to an interesting\ntype-II multiferroic behavior. However, so far no other multiferroic material\nin the tungstate family has been found. In this work, we present the synthesis\nand the systematic study of the double tungstate LiFe(WO$_4$)$_2$. Experimental\ncharacterizations including structural, thermodynamic, magnetic, neutron powder\ndiffraction, and pyroelectric measurements, unambiguously confirm that\nLiFe(WO$_4$)$_2$ is the secondly found multiferroic system in the tungstate\nfamily. The cycloidal magnetism driven ferroelectricity is also verified by\ndensity functional theory calculations. Although here the magnetic couplings\nbetween Fe ions are indirect, namely via the so-called super-super-exchanges,\nthe temperatures of magnetic and ferroelectric transitions are surprisingly\nmuch higher than those of MnWO$_4$."
    },
    {
        "anchor": "Fabrication and structural characterization of diamond-coated tungsten\n  tips: Coating metal nanotips with a negative electron affinity material like\nhydrogen-terminated diamond bears promise for a high brightness photocathode.\nWe report a recipe on the fabrication of diamond coated tungsten tips. A\ntungsten wire is etched electrochemically to a nanometer sharp tip, dip-seeded\nin diamond suspension and subsequently overgrown with a diamond film by\nplasma-enhanced chemical vapor deposition. With dip-seeding only, the seeding\ndensity declines towards the tip apex due to seed migration during solvent\nevaporation. The migration of seeds can be counteracted by nitrogen gas flow\ntowards the apex, which makes coating of the apex with nanometer-thin diamond\npossible. At moderate gas flow, diamond grows homogeneously at shaft and apex\nwhereas at high flow diamond grows in the apex region only. With this\ntechnique, we achieve a thickness of a few tens of nanometers of diamond\ncoating within less than 1 $\\mu$m away from the apex. Conventional transmission\nelectron microscopy (TEM), electron diffraction and electron energy loss\nspectroscopy confirm that the coating is composed of dense nanocrystalline\ndiamond with a typical grain size of 20 nm. High resolution TEM reveals\ngraphitic paths between the diamond grains.",
        "positive": "In search of antiferromagnetic interlayer coupling in diluted magnetic\n  thin films with RKKY interaction: We study a model thin film containing diluted bilayer structure with the RKKY\nlong-range interaction. The magnetic subsystem is composed of two magnetically\ndoped layers, separated by an undoped nonmagnetic spacer and placed inside a\nwider film modelled by a quantum well of infinite depth. We focus our study on\nthe range of parameters for which the antiferromagnetic coupling between the\nmagnetic layers can be expected. The critical temperatures for such system are\nfound and their dependence on magnetic layer thickness and charge carriers\nconcentration is discussed. The magnetization distribution within each magnetic\nlayer is calculated as a function of layer thickness. The external field\nrequired to switch the mutual orientation of layer magnetizations from\nantiferromagnetic to ferromagnetic state is also discussed."
    },
    {
        "anchor": "Effective spin-mixing conductance of heavy-metal-ferromagnet interfaces: The effective spin-mixing conductance (G_eff) of a heavy metal/ferromagnet\n(HM/FM) interface characterizes the efficiency of the interfacial spin\ntransport.Accurately determining G_eff is critical to the quantitative\nunderstanding of measurements of direct and inverse spin Hall effects. G_eff is\ntypically ascertained from the inverse dependence of magnetic damping on the FM\nthickness under the assumption that spin pumping is the dominant mechanism\naffecting this dependence.Here we report that, this assumption fails badly in\nmany in-plane magnetized prototypical HM/FM systems in the nm-scale thickness\nregime. Instead, the majority of the damping is from two-magnon scattering at\nthe FM interface, while spin-memory-loss scattering at the interface can also\nbe significant.If these two effects are neglected, the results will be an\nunphysical \"giant\" apparent G_eff and hence considerable underestimation of\nboth the spin Hall ratio and the spin Hall conductivity in inverse/direct spin\nHall experiments.",
        "positive": "Role of the Non-Collinear Polarizer Layer in Spin Transfer Torque\n  Switching Processes: We have recently reported that the spin transfer torque switching current\ndensity is very sensitive to not only the junction sizes but also the exchange\nstiffness constants of the free layer according to the micromagnetic\nsimulations. The results are very complicate and far from the macro-spin model\nbecause of the non-coherent spin switching processes. The dependence of the\nswitching current density on the junction sizes and the exchange stiffness\nconstants becomes systematic when we employ the non-collinear polarizer layer.\nIt is found that the non-collinear polarizer layer enhances the coherency of\nthe spin dynamics by breaking symmetric spin configurations."
    },
    {
        "anchor": "Ab initio approach for thermodynamic surface phases with full\n  consideration of anharmonic effects -- the example of hydrogen at Si(100): A reliable description of surfaces structures in a reactive environment is\ncrucial to understand materials functions. We present a first-principles theory\nof replica-exchange grand-canonical-ensemble molecular dynamics (REGC-MD) and\napply it to evaluate phase equilibria of surfaces in reactive gas-phase\nenvironment. We identify the different surface phases and locate phase\nboundaries including triple and critical points. The approach is demonstrated\nby addressing open questions for the Si(100) surface in contact with a hydrogen\natmosphere. In the range from 300 to 1 000 K, we find 25 distinct\nthermodynamically stable surface phases, for which we also provide microscopic\ndescriptions. Most of the identified phases, including few order-disorder phase\ntransitions, have not yet been observed experimentally. The REGC-MD-derived\nphase diagram shows significant, qualitative differences to the description by\nthe state-of-the-art \"ab initio atomistic thermodynamics\" approach.",
        "positive": "Ground states and magnetization process for an triangular lattice array\n  of magnetic dots with perpendicular anisotropy: We analyzed the ground state of the array of magnetic particles (magnetic\ndots) which form a two-dimensional triangular lattice, and magnetic moment of\nwhich is perpendicular to the plane of the lattice, in the presence of external\nmagnetic field. In the small fields long range dipole-dipole interaction leads\nto the specific antiferromagnetic order, where two out of six nearest neighbors\nof the particle have the same direction of magnetization moment and four - the\nopposite one. It is shown that magnetization process in such array of particles\nas opposed to the rectangular lattices results from the formation of the\nmagnetized topological defects (dislocations) in the shape of the domain walls."
    },
    {
        "anchor": "FEpX -- Finite Element Polycrystals: Theory, Finite Element Formulation,\n  Numerical Implementation and Illustrative Examples: FEpX is a modeling framework for computing the elastoplastic deformations of\npolycrystalline solids. Using the framework, one can simulate the mechanical\nbehavior of aggregates of crystals, referred to as virtual polycrystals, over\nlarge strain deformation paths. This article presents the theory, the finite\nelement formulation, and important features of the numerical implementation\nthat collectively define the modeling framework. The article also provides\nseveral examples of simulating the elastoplastic behavior of polycrystalline\nsolids to illustrate possible applications of the framework. There is an\nassociated finite element code, also referred to as FEpX, that is based on the\nframework presented here and was used to perform the simulations presented in\nthe examples. The article serves as a citable reference for the modeling\nframework for users of that code. Specific information about the formats of the\ninput and output data, the code architecture, and the code archive are\ncontained in other documents.",
        "positive": "Pressure-induced 1T to 3R structural phase transition in metallic VSe2:\n  X-ray diffraction and first-principles theory: We study pressure-induced structural evolution of vanadium diselenide (VSe2),\na 1T polymorphic member of the transition metal di-chalcogenide (TMD) family\nusing synchrotron-based powder X-ray diffraction (PXRD) and first-principles\ndensity functional theory (DFT). Our XRD results reveal anomalies at P ~4 GPa\nin c/a ratio, V-Se bond length and Se-V-Se bond angle signalling an\nisostructural transition. This is followed by a first order structural\ntransition from 1T (space group P-3m1) phase to a 3R (space group R-3m) phase\nat P ~11 GPa due to sliding of adjacent Se-V-Se layers. We present various\nscenarios to understand the experimental results within DFT and find that the\n1T to 3R transition can be captured only after inclusion of enthalpic\ncorrection associated with errors in cell volume with underestimated transition\npressure. The abrupt increase in the Debye-Waller factors of Se atoms by a\nfactor of ~4 and hence the anharmonic effects across the structural transition\npressure are hitherto not reported so far and hint a possible way to understand\nthe mismatch between the experimental and theoretical transition pressure\nvalues."
    },
    {
        "anchor": "Thermal instability of decahedral structures in platinum nanoparticles: We conduct molecular dynamics simulations of 887 and 1389-atom decahedral\nplatinum nanoparticles using an embedded atom potential. By constructing\nmicrocanonical caloric curves, we identify structural transitions from\ndecahedral to fcc in the particles prior to melting. The transitions take place\nduring phase coexistence and appear to occur via melting of the decahedral\nstructure and subsequent recrystallisation into the fcc structure.",
        "positive": "Lattice polarization effects on the screened Coulomb interaction $W$ of\n  the GW approximation: In polar insulators where longitudinal and transverse optical phonon modes\ndiffer substantially, the electron-phonon coupling affects the energy-band\nstructure primarily through the long-range Fr\\\"ohlich contribution to the Fan\nterm. This diagram has the same structure as the $GW$ self-energy where $W$\noriginates from the electron part of the screened coulomb interaction. The two\ncan be conveniently combined by combining electron and lattice contributions to\nthe polarizability. Both contributions are nonanalytic at the origin, and\ndiverge as $1/q^2$ so that the predominant contribution comes from a small\nregion around $q{=}0$. Here we adopt a simple estimate for the Fr\\\"ohlich\ncontribution by assuming that the entire phonon part can be attributed to a\nsmall volume of $q$ near $q{=}0$. We estimate the magnitude for\n$\\mathbf{q}{\\rightarrow}0$ from a generalized Lyddane-Sachs-Teller relation,\nand the radius from the inverse of the polaron length scale. The gap correction\nis shown to agree with Fr\\\"ohlich's simple estimate $-\\alpha_P\\omega_L/2$ of\nthe polaron effect."
    },
    {
        "anchor": "Occupational Disorder as the Origin of Flattening of the Acoustic Phonon\n  Branches in the Clathrate Ba$_{8}$Ga$_{16}$Ge$_{30}$: In the search for high-performance thermoelectrics, materials such as\nclathrates have drawn attention due to having both glass-like low phonon\nthermal conductivity and crystal-like high electrical conductivity.\nBa$_{8}$Ga$_{16}$Ge$_{30}$ (BGG) has a loosely bound guest Ba atom trapped\ninside rigid Ga/Ge cage structures. Avoided crossings between acoustic phonons\nand the flat guest atom branches have been proposed to be the source of the low\nlattice thermal conductivity of BGG. Ga/Ge site disorder with Ga and Ge\nexchanging places in different unit cells has also been reported. We used\ntime-of-flight neutron scattering to measure the complete phonon spectrum in a\nlarge single crystal of BGG and compared these results with predictions of\ndensity functional theory to elucidate the effect of the disorder on\nheat-carrying phonons. Experimental results agreed much better with the\ncalculation assuming the disorder than with the calculation assuming the\nordered configuration. Although atomic masses of Ga and Ge are nearly\nidentical, we found that disorder strongly reduces phonon group velocities,\nwhich significantly reduces thermal conductivity. Our work points at a new path\ntowards optimizing thermoelectrics.",
        "positive": "Gigantic Anisotropy of Self-Induced Spin-Orbit Torque in Weyl\n  Ferromagnet Co2MnGa: Spin-orbit torque (SOT) is receiving tremendous attention from both\nfundamental and application-oriented aspects. Co2MnGa, a Weyl ferromagnet that\nis in a class of topological quantum materials, possesses cubic-based high\nstructural symmetry, the L21 crystal ordering, which should be incapable of\nhosting anisotropic SOT in conventional understanding. Here we show the\ndiscovery of a gigantic anisotropy of self-induced SOT in Co2MnGa. The\nmagnitude of the SOT is comparable to that of heavy metal/ferromagnet bilayer\nsystems despite the high inversion symmetry of the Co2MnGa structure. More\nsurprisingly, a sign inversion of the self-induced SOT is observed for\ndifferent crystal axes. This finding stems from the interplay of the\ntopological nature of the electronic states and their strong modulation by\nexternal strain. Our research enriches the understanding of the physics of\nself-induced SOT and demonstrates a versatile method for tuning SOT\nefficiencies in a wide range of materials for topological and spintronic\ndevices."
    },
    {
        "anchor": "Magnetic domain wall motion by spin transfer: The discovery that a spin polarized current can exert a large torque on a\nferromagnet through a transfusion of spin angular momentum, offers a new way to\ncontrol a magnetization by simple current injection, without the help of an\napplied external field. Spin transfer can be used to induce magnetization\nreversals and oscillations, or to control the position of a magnetic domain\nwall. In this review, we focus on this last mechanism, which is today the\nsubject of an extensive research, both because the microscopic details for its\norigin are still debated, but also because promising applications are at stake\nfor non-volatile magnetic memories.",
        "positive": "First-principles calculations on the mechanical, electronic, magnetic\n  and optical properties of two-dimensional Janus Cr$_2$TeX (X= P, As, Sb)\n  monolayers: Janus materials possess extraordinary physical, chemical, and mechanical\nproperties caused by symmetry breaking. Here, the mechanic properties,\nelectronic structure, magnetic properties, and optical properties of Janus\nCr$_2$TeX (X= P, As, Sb) monolayers are systematically investigated by the\ndensity functional theory. Janus Cr$_2$TeP, Cr$_2$TeAs, and Cr$_2$TeSb are\nintrinsic ferromagnetic (FM) half-metals with wide spin gaps and half-metallic\ngaps. Monte Carlo simulations based on the Heisenberg model estimate the Curie\ntemperature (\\emph{T}$_c$) of these monolayers are about 583, 608, and 597 K,\nrespectively. Additionally, it is found that Cr$_2$TeX (X= P, As, Sb)\nmonolayers still exhibit FM half-metallic properties under biaxial strain from\n-6% to 6%. At last, the Cr$_2$TeP monolayer has a higher absorption coefficient\nthan the Cr$_2$TeAs and Cr$_2$TeSb monolayers in the visible region. The\nresults predict that Janus Cr$_2$TeX (X= P, As, Sb) monolayers with novel\nproperties have good potential for applications in future nanodevices."
    },
    {
        "anchor": "Graphene-based spintronic components: A major challenge of spintronics is in generating, controlling and detecting\nspin-polarized current. Manipulation of spin-polarized current, in particular,\nis difficult. We demonstrate here, based on calculated transport properties of\ngraphene nanoribbons, that nearly +-100% spin-polarized current can be\ngenerated in zigzag graphene nanoribbons (ZGNRs) and tuned by a source-drain\nvoltage in the bipolar spin diode, in addition to magnetic configurations of\nthe electrodes. This unusual transport property is attributed to the intrinsic\ntransmission selection rule of the spin subbands near the Fermi level in ZGNRs.\nThe simultaneous control of spin current by the bias voltage and the magnetic\nconfigurations of the electrodes provides an opportunity to implement a whole\nrange of spintronics devices. We propose theoretical designs for a complete set\nof basic spintronic devices, including bipolar spin diode, transistor and logic\ngates, based on ZGNRs.",
        "positive": "High-pressure neutron study of the morphotropic PZT: phase transitions\n  in a two-phase system: In piezoelectric ceramics the changes in the phase stabilities versus stress\nand temperature in the vicinity of the phase boundary play a central role. The\npresent study was dedicated to the classical piezoelectric,\nlead-zirconate-titanate (PZT) ceramic with composition\nPb(Zr$_{0.54}$Ti$_{0.46}$)O$_3$ at the Zr-rich side of the morphotropic phase\nboundary at which both intrinsic and extrinsic contributions to\npiezoelectricity are significant. The pressure-induced changes in this\ntwo-phase (rhombohedral $R3c$+monoclinic $Cm$ at room temperature and\n$R3c+P4mm$ above 1 GPa pressures) system were studied by high-pressure neutron\npowder diffraction technique. The experiments show that applying pressure\nfavors the $R3c$ phase, whereas the $Cm$ phase transforms continuously to the\n$P4mm$, which is favored at elevated temperatures due to the competing entropy\nterm. The $Cm\\rightarrow R3c$ phase transformation is discontinuous. The\ntransformation contributes to the extrinsic piezoelectricity. An important\ncontribution to the intrinsic piezoelectricity was revealed: a large\ndisplacement of the $B$ cations (Zr and Ti) with respect to the oxygen anions\nis induced by pressure. Above 600 K a phase transition to a cubic phase took\nplace. Balance between the competing terms dictates the curvature of the phase\nboundary. After high-pressure experiments the amount of rhombohedral phase was\nlarger than initially, suggesting that on the Zr-rich side of the phase\nboundary the monoclinic phase is metastable."
    },
    {
        "anchor": "A nonlinear symmetry breaking effect in shear cracks: Shear cracks propagation is a basic dynamical process that mediates\ninterfacial failure. We develop a general weakly nonlinear elastic theory of\nshear cracks and show that these experience tensile-mode crack tip deformation,\nincluding possibly opening displacements, in agreement with Stephenson's\nprediction. We quantify this nonlinear symmetry breaking effect, under\ntwo-dimensional deformation conditions, by an explicit inequality in terms of\nthe first and second order elastic constants in the quasi-static regime and\nsemi-analytic calculations in the fully dynamic regime. Our general results are\napplied to various materials. Finally, we discuss available works in the\nliterature and note the potential relevance of elastic nonlinearities for\nfrictional cracks.",
        "positive": "Hydrodynamic theory of freezing: Nucleation and polycrystalline growth: Structural aspects of crystal nucleation in undercooled liquids are explored\nusing a nonlinear hydrodynamic theory of crystallization proposed recently [G.\nI. Toth et al., J. Phys.: Condens. Matter 26, 055001 (2014)], which is based on\ncombining fluctuating hydrodynamics with the phase-field crystal theory. We\nshow that in this hydrodynamic approach not only homogeneous and heterogeneous\nnucleation processes are accessible, but also growth front nucleation, which\nleads to the formation of new (differently oriented) grains at the solid-liquid\nfront in highly undercooled systems. Formation of dislocations at the\nsolid-liquid interface and interference of density waves ahead of the\ncrystallization front are responsible for the appearance of the new\norientations at the growth front that lead to spherulite-like nanostructures."
    },
    {
        "anchor": "Microstructure and structural modulation of lutetium dihydride LuH2 as\n  seen via transmission electron microscopy: Structural investigations conducted using transmission electron microscopy\n(TEM) on LuH2 synthesized under atmospheric pressure (AP-LuH2) and\nnitrogen-doped LuH2 synthesized under high pressure (HP-LuH2) have revealed\nnumerous microstructural phenomena. Both materials show a clear superstructure\nmodulation with wave vector, q^* = 1/4 (2-20), and this modulation can be well\ninterpreted by the displacements of Lu atoms. Further investigations on the\nnitrogen-doped HP-LuH2 materials reveal the appearance of high-density\nantiphase boundaries, in particular, domain walls of a few atomic layer\nthickness without structural modulation can be observed, suggesting possible\ninterface properties could be detected in this system. In-situ TEM observations\nof AP-LuH2 suggest that no evident structural phase transition occurs between\n94 K and 673 K.",
        "positive": "Domain structure dynamics in the ferromagnetic Kagome-lattice Weyl\n  semimetal Co$_3$Sn$_2$S$_2$: Co$_3$Sn$_2$S$_2$, a Weyl semimetal that consists of layers of Kagome\nlattices, transitions from a high-temperature paramagnetic phase to a\nlow-temperature ferromagnetic phase below 177 K. The phase transition occurs\nthrough an intermediate non-trivial magnetic phase, the so-called \"A\"-phase\njust below the Curie temperature. The \"A\"-phase was earlier linked with a\ncompeting anti-ferromagnetic phase, a spin-glass phase and certain indirect\nmeasurements indicated the possibility of magnetic Skyrmions in this phase. We\nhave imaged the magnetic domain structure in a single crystal of\nCo$_3$Sn$_2$S$_2$ at different temperatures, magnetic fields and field-angles\nby magnetic force microscopy. At low temperatures, we observed stripe domains\nindicating presence of uniaxial anisotropy. Above 130 K, the domain walls\nbecome mobile and they tend to align relatively easily when the magnetic field\nis increased along the $c$-axis than in the $a-b$ plane. Our detailed study of\nfield-dependent domain dynamics reveal that the anomalous nature of the phase\ntransition just below $T_c$ is dominantly governed by domain wall motion."
    },
    {
        "anchor": "Towards the growth of single-crystal boron nitride monolayer on Cu: Atom-layered hexagonal boron nitride (hBN), with excellent stability, flat\nsurface and large bandgap, has been reported to be the best 2D insulator to\nopen up the great possibilities for exciting potential applications in\nelectronics, optoelectronics and photovoltaics. The ability to grow\nhigh-quality large single crystals of hBN is at the heart for those\napplications, but the size of single-crystal 2D BN is less than a millimetre\ntill now. Here, we report the first epitaxial growth of a 10*10 cm2\nsingle-crystal hBN monolayer on a low symmetry Cu(110) \"vicinal surface\". The\ngrowth kinetics, unidirectional alignment and seamless stitching of hBN domains\nare unambiguously illustrated using centimetre- to the atomic-scale\ncharacterization techniques. The findings in this work are expected to\nsignificantly boost the massive applications of 2D materials-based devices, and\nalso pave the way for the epitaxial growth of broad non-centrosymmetric 2D\nmaterials.",
        "positive": "Spectrally-resolved dielectric function of amorphous and crystalline\n  GeTe nanoparticle thin films: Phase-change materials (PCMs), which are well-established in optical and\nrandom-access memories, are increasingly studied for emerging topics such as\nbrain-inspired computing and active photonics. These applications take\nadvantage of the pronounced reflectivity and resistivity changes that accompany\nthe structural transition in PCMs from their amorphous to crystalline state.\nHowever, PCMs are typically fabricated as thin films via sputtering, which is\ncostly, requires advanced equipment, and limits the sample and device design.\nHere, we investigate a simpler and more flexi-ble approach for applications in\ntunable photonics: the use of sub-10 nm colloidal PCM nanoparticles (NPs). We\nreport the optical properties of amorphous and crystalline germanium telluride\n(GeTe) NP thin films from the infrared to the ultraviolet spectral range. Using\nspectroscopic ellipsometry with support from cross-sectional scanning electron\nmicroscopy, atomic force microscopy, and absorption spectroscopy, we extract\nrefractive indices n, extinction coefficients k, and band gaps Eg and compare\nto values known for sputtered GeTe thin films. We find a decrease of n and k\nand an increase of Eg for NP-based GeTe films, yielding insights into\nsize-dependent property changes for nanoscale PCMs. Furthermore, our results\nreveal the suitability of GeTe NPs for tunable photonics in the near-infrared\nand visible spectral range. Finally, we studied sample reproducibility and\naging of our NP films. We found that the colloidally-prepared PCM thin films\nwere stable for at least two months stored under nitrogen, further supporting\nthe great promise of these materials in applications."
    },
    {
        "anchor": "SPS-Sintered NaTaO3-Fe2O3 Composite exhibits Large Seebeck Coefficient\n  and Electric Current: NaTaO3-50wt% Fe2O3 composite ceramics showed a large Seebeck voltage of -300\nmV at a temperature gradient of 650 K yielding a constant Seebeck coefficient\nof more than -500 microV/K over a wide temperature range. We report for the\nfirst time that SPS sintering at low temperature 870K could maintain the\nshort-circuit current of -80 microA, which makes this thermoelectric material a\npossible candidate for high-temperature applications up to 1623 K. The reason\nfor the good performance is the interface between Fe2O3 and surrounding NaTaO3\nperovskite. When spark-plasma sintering (SPS) is used, constitutional vacancies\ndisappeared and the electric conductivity increases remarkably yielding ZT of\n0.016.",
        "positive": "Modeling solid-state dewetting of a single-crystal binary alloy thin\n  films: Dewetting of a binary alloy thin film is studied using a continuum\nmany-parameter model that accounts for the surface and bulk diffusion, the bulk\nphase separation, the surface segregation and the particles formation.\nAnalytical solution is found for the quasistatic equilibrium concentration of a\nsurface-segregated atomic species. This solution is factored into the nonlinear\nand coupled evolution PDEs for the bulk composition and surface morphology.\nStability of a planar film surface with respect to small perturbations of the\nshape and composition is analyzed, revealing the dependence of the particles\nsize on major physical parameters. Computations show various scenarios of the\nparticles formation and the redistribution of the alloy components inside the\nparticles and on their surface. In most situations, for the alloy film composed\ninitially of 50% A and 50% B atoms, a core-shell particles are formed, and they\nare located atop a wetting layer that is modestly rich in the B phase. Then the\nparticles shell is the nanometric segregated layer of the A phase, and the core\nis the alloy that is modestly rich in the A phase."
    },
    {
        "anchor": "Chalcogenide perovskite BaZrS3 thin-film electronic and optoelectronic\n  devices by low temperature processing: Owing to its superior visible light absorption and high chemical stability,\nchalcogenide perovskite barium zirconium sulfide has attracted significant\nattention in the past few years as a potential alternative to hybrid halide\nperovskites for optoelectronics. However, the high processing temperatures of\nBaZrS3 thin films at above 1000 C severely limits their potential for device\napplications. Herein, we report the synthesis of BaZrS3 thin films at\ntemperatures as low as 500 C, by changing the chemical reaction pathway. The\nsingle phase BaZrS3 thin film was confirmed by X-ray diffraction and Raman\nspectroscopies. Atomic force microscopy and scanning electron microscopy show\nthat crystalline size and surface roughness were consistently reduced with\ndecreasing annealing temperature. The lower temperatures further eliminate\nsulfur vacancies and carbon contaminations associated with high temperature\nprocessing. The ability to synthesize chalcogenide perovskite thin films at\nlower temperatures removes a major hurdle for their device fabrication. The\nphotodetectors demonstrate fast response and an on/off ratio of 80. The\nfabricated field effect transistors show an ambipolar behavior with electron\nand hole mobilities of 16.8 cm2/Vs and 2.6 cm2/Vs, respectively.",
        "positive": "Large topological Hall effect in an easy-cone ferromagnet (Cr0.9B0.1)Te: The Berry phase understanding of electronic properties has attracted special\ninterest in condensed matter physics, leading to phenomena such as the\nanomalous Hall effect and the topological Hall effect. A non-vanishing Berry\nphase, induced in momentum space by the band structure or in real space by a\nnon-coplanar spin structure, is the origin of both effects. Here, we report a\nsign conversion of the anomalous Hall effect and a large topological Hall\neffect in (Cr0.9B0.1)Te single crystals. The spin reorientation from an\neasy-axis structure at high temperature to an easy-cone structure below 140 K\nleads to conversion of the Berry curvature, which influences both, anomalous\nand topological, Hall effects in the presence of an applied magnetic field and\ncurrent. We compare and summarize the topological Hall effect in four\ncategories with different mechanisms and have a discussion into the possible\nartificial fake effect of topological Hall effect in polycrystalline samples,\nwhich provides a deep understanding of the relation between spin structure and\nHall properties."
    },
    {
        "anchor": "The Origin of Deformation Induced Topological Anisotropy in Silica Glass: Oxide glasses with a network structure are omnipresent in daily life. Often,\nthey are regarded as isotropic materials; however, structural anisotropy can be\ninduced through processing in mechanical fields and leads to unique materials\nproperties. Unfortunately, due to the lack of local, atomic-scale analysis\nmethods, the microscopic mechanisms leading to anisotropy remained elusive.\nUsing novel analysis methods on glasses generated by molecular dynamics\nsimulations, this paper provides a microscopic understanding of topological\nanisotropy in silica (SiO$_2$) glass under mechanical loads. The anisotropy\nobserved in silica glass originates from a preferred orientation of SiO$_4$\ntetrahedra at both short- and medium-range levels that can be controlled via\nthe mode of mechanical loading. The findings elucidate the relation between the\ndeformation protocol and the resulting anisotropic structure of the silica\nnetwork (involving both persistent and transient effects), and thus provide\nimportant insight for the design of oxide glasses with tailored materials\nproperties.",
        "positive": "Formation of non-cubic nanoparticles from cubic MgO in intensified\n  self-burning of magnesium: When Mg metal burns in air the resulting rock-salt MgO smoke consists of\nperfect [100] cubes of about 100 nm. On contrast, we found that intensification\nof self-burning of Mg micropowder either by injecting it into oxy-hydrogen\ndiffusion flame or under an infrared laser beam switches the growth mechanism\nproducing mostly single-crystalline spheres and terraced nanoparticles. MgO\nmolecule condensation onto primary spherical nanoparticles can account for\ngeneration of terraced nanoparticles with regular steps proportional to the\nnanoparticle size."
    },
    {
        "anchor": "On the influence of nanometer-thin antiferromagnetic surface layer on\n  ferromagnetic CrO$_2$: We present magnetic stray field measurements performed on a single\nmicro-crystal of the half metallic ferromagnet CrO$_2$, covered by a naturally\ngrown 2\\,-\\,5\\,nm surface layer of antiferromagnetic (AFM) Cr$_2$O$_3$. The\ntemperature variation of the stray field of the micro-crystal measured by\nmicro-Hall magnetometry shows an anomalous increase below $\\sim$\\,60\\,K. We\nfind clear evidence that this behavior is due to the influence of the AFM\nsurface layer, which could not be isolated in the corresponding bulk\nmagnetization data measured using SQUID magnetometry. The distribution of\npinning potentials, analyzed from Barkhausen jumps, exhibits a similar\ntemperature dependence. Overall, the results indicate that the surface layer\nplays a role in defining the potential landscape seen by the domain\nconfiguration in the ferromagnetic grain.",
        "positive": "Defects-driven magnetism in bulk $\u03b1$-Li$ _{3}$N: \\textit{Ab-initio} calculations based on density functional theory with local\nspin density approximation are used to study defects-driven magnetism in bulk\n$\\alpha$-Li$ _{3}$N. Our calculations show that bulk Li$ _{3} $N is a\nnon-magnetic semiconductor. Two types of Li vacancies (Li-I and Li-II) are\nconsidered, and Li-vacancies (either Li-I or Li-II type) can induce magnetism\nin Li$ _{3}$N with a total magnetic moment of 1.0 $\\mu_{\\rm B}$ which arises\nmainly due to partially occupied N-$p$-orbitals around the Li vacancies. The\ndefect formation energies dictate that Li-II vacancy, which is in the Li$\n_{2}$N plane, is thermodynamically more stable as compared with Li-I vacancy.\nThe electronic structures of Li-vacancies show half-metallic behavior. On the\nother hand N-vacancy does not induce magnetism and has a larger formation\nenergy than Li-vacancies. N vacancy derived bands at the Fermi energy are\nmainly contributed by the Li atoms. Carbon is also doped at Li-I and Li-II\nsites, and it is expected that doping C at Li-I site is thermodynamically more\nstable as compared with Li-II site. Carbon can induce metallicity with zero\nmagnetic moment when doped at Li-I site, whereas magnetism is observed when\nLi-II site is occupied by the C impurity atom and C-driven magnetism is spread\nover the N atoms as well. Carbon can also induce half-metallic magnetism when\ndoped at N site in Li$ _{3}$N, and has a smaller defect formation energy as\ncompared with Li-II site doping. The ferromagnetic (FM) and antiferromagnetic\n(AFM) coupling between the C atoms is also investigated, and we conclude that\nFM state is more stable than the AFM state."
    },
    {
        "anchor": "Probing local lattice distortion in medium- and high-entropy alloys: The atomic-level tunability that results from alloying multiple transition\nmetals with d electrons in concentrated solid solution alloys (CSAs), including\nhigh-entropy alloys (HEAs), has produced remarkable properties for advanced\nenergy applications, in particular, damage resistance in high-radiation\nenvironments. The key to understanding CSAs radiation performance is\nquantitatively characterizing their complex local physical and chemical\nenvironments. In this study, the local structure of a FeCoNiCrPd HEA is\nquantitatively analyzed with X-ray total scattering and extended X-ray\nabsorption fine structure methods. Compared to FeCoNiCr and FeCoNiCrMn,\nFeCoNiCrPd with a quasi-random alloy structure has a strong local lattice\ndistortion, which effectively pins radiation-induced defects. Distinct from a\nrelaxation behavior in FeCoNiCr and FeCoNiCrMn, ion irradiation further\nenhanced the local lattice distortion in FeCoNiCrPd due to a preference for\nforming Pd-Pd atomic pairs.",
        "positive": "Mechanical Properties of Penta-Graphene Nanotubes: Penta-graphene is the name given to a novel puckered monolayer of carbon\natoms tightly packed into an inerratic pentagonal network, theoretically, which\nexhibits excellent thermal and mechanical stability and can be rolled into\npenta-graphene nanotubes (PGNTs). Herein, we perform the first simulation study\nof mechanical properties of PGNTs under uniaxial tension. In addition to\ncomparable mechanical properties with that of carbon nanotubes (CNT), it is\nfound that PGNTs possess promising extensibility with typical plastic behavior\ndue to the irreversible pentagon-to-polygon structural transformation and the\nhexagon carbon ring becomes the dominating structural motif after the\ntransformation. The plastic characteristic of PGNTs is inherent with\nstrain-rate and tube-diameter independences. Moreover, within ultimate\ntemperature (T<1100 K), tensile deformed PGNTs manifest similar phase\ntransition with an approximate transition ratio from pentagon to hexagon. The\nintrinsic insight provides a fundamental understanding of mechanic properties\nof PGNTs, which should open up a novel perspective for the design of plastic\ncarbon-based nanomaterials."
    },
    {
        "anchor": "Magnetoelectric effect in layered ferrite/PZT composites. Study of the\n  demagnetizing effect on the magnetoelectric behavior: We report the use of high magnetomechanical coupling ferrites in\nmagnetoelectric (ME) layered composites. Bilayer samples combining $(Ni_{0.973}\nCo_{0.027})_{1-x} Zn_x Fe_2 O_4$ ferrites ($x = 0-0.5$) synthesized by non\nconventional reactive Spark Plasma Sintering and commercial lead zirconate\ntitanate (PZT) were characterized in term of ME voltage coefficients measured\nat sub-resonant frequency. Strong ME effects are obtained and we show that an\nannealing at 1000$^\\circ$C and a quenching in air improve the piezomagnetic\nbehavior of Zn-rich compositions. A theoretical model that predicts the ME\nbehavior was developed, focusing our work on the demagnetizing effects in the\ntransversal mode as well as the longitudinal mode. The model shows that: (i)\nhigh ME coefficients are obtained when ferrites with high magnetomechanical\ncoupling are used in bilayer ME composites, (ii) the ME behavior in transversal\nand longitudinal modes is quite similar, and differences in the shapes of the\nME curves are mainly due the demagnetizing effects, (iii) in the transversal\nmode, the magnetic field penetration depends on the ferrite layer thickness and\nthe ME coefficient is affected accordingly. The two later points are confirmed\nby measurements on ME samples and calculations. Performances of the ME\ncomposites made with high magnetomechanical coupling ferrites are compared to\nthose obtained using Terfenol-D materials in the same conditions of size,\nshape, and volume ratio. It appears that a ferrite with an optimized\ncomposition has performances comparable to those obtained with Terfenol-D\nmaterial. Nevertheless, the fabrication processes of ferrites are quite\nsimpler. Finally, a ferrite/PZT based ME composite was used as a current\nsensor.",
        "positive": "Optical signatures of multifold fermions in the chiral topological\n  semimetal CoSi: We report the optical conductivity in high-quality crystals of the chiral\ntopological semimetal CoSi, which hosts exotic quasiparticles known as\nmultifold fermions. We find that the optical response is separated into several\ndistinct regions as a function of frequency, each dominated by different types\nof quasiparticles. The low-frequency intraband response is captured by a narrow\nDrude peak from a high-mobility electron pocket of double Weyl quasi-particles,\nand the temperature dependence of the spectral weight is consistent with its\nFermi velocity. By subtracting the low-frequency sharp Drude and phonon peaks\nat low temperatures, we reveal two intermediate quasi-linear inter-band\ncontributions separated by a kink at 0.2 eV. Using Wannier tight-binding models\nbased on first-principle calculations, we link the optical conductivity above\nand below 0.2 eV to interband transitions near the double Weyl fermion and a\nthreefold fermion, respectively. We analyze and determine the chemical\npotential relative to the energy of the threefold fermion, revealing the\nimportance of transitions between a linearly dispersing band and a flat band.\nMore strikingly, below 0.1 eV our data are best explained if spin-orbit\ncoupling is included, suggesting that at these energies the optical response is\ngoverned by transitions between a previously unobserved four-fold spin-3/2 node\nand a Weyl node. Our comprehensive combined experimental and theoretical study\nprovides a way to resolve different types of multifold fermions in CoSi at\ndifferent energy. More broadly our results provide the necessary basis to\ninterpret the burgeoning set of optical and transport experiments in chiral\ntopological semimetals."
    },
    {
        "anchor": "Quasi-nondegenerate pump-probe magnetooptical experiment in GaAs/AlGaAs\n  heterostructure based on spectral filtration: We report on a quasi-nondegenerate pump-probe technique that is based on\nspectral-filtration of femtosecond laser pulses by a pair of\nmutually-spectrally-disjunctive interference filters. This cost- and\nspace-efficient approach can be used even in pump-probe microscopy where\ncollinear propagation of pump and probe pulses is dictated by utilization of a\nmicroscopic objective. This technique solves the contradictory requirements on\nan efficient removal of pump photons from the probe beam, to achieve a good\nsignal-to-noise ratio, simultaneously with a needed spectral proximity of the\nexcitation and probing, which is essential for magnetooptical study of many\nmaterial systems. Importantly, this spectral-filtration of 100 fs long laser\npulses does not affect considerably the resulting time-resolution, which\nremains well below 500 fs. We demonstrate the practical applicability of this\ntechnique with close but distinct wavelengths of pump and probe pulses in\nspatially- and time-resolved spin-sensitive magnetooptical Kerr effect (MOKE)\nexperiment in GaAs/AlGaAs heterostructure, where a high-mobility spin system is\nformed after optical injection of electrons at wavelengths close to MOKE\nresonance. In particular, we studied the time- and spatial-evolutions of\ncharge-related (reflectivity) and spin-related (MOKE) signals. We revealed that\nthey evolve in a similar but not exactly the same way which we attributed to\ninterplay of several electron many-body effects in GaAs.",
        "positive": "Kirchhoff rods with nonhomogeneous cross section: The Kirchhoff's theory for thin, inextensible, elastic rods with\nnonhomogeneous cross section is studied. The Young's and shear moduli of the\nrod are considered to vary radially, and it is shown that an analytical\nsolution for the constitutive relations can be obtained for circular cross\nsection and constant Poisson's ratio. We comment on possible applications of\nour results."
    },
    {
        "anchor": "Theory of charge density wave depinning by electromechanical effect: We discuss the first theory for the depinning of low dimensional,\nincommensurate, charge density waves (CDWs) in the strong electron-phonon (e-p)\nregime. Arguing that most real CDWs systems invariably develop a gigantic\ndielectric constant (GDC) at very low frequencies, we propose an\nelectromechanical mechanism which is based on a local field effect. At zero\nelectric field and large enough e-p coupling the structures are naturally\npinned by the lattice due to its discreteness, and develop modulation functions\nwhich are characterized by discontinuities. When the electric field is turned\non, we show that it exists a finite threshold value for the electric field\nabove which the discontinuities of the modulation functions vanish due to CDW\ndeformation. The CDW is then free to move. The signature of this\npinning/depinning transition as a function of the increasing electric field can\nbe directly observed in the phonon spectrum by using inelastic neutrons or\nX-rays experiments.",
        "positive": "Ratchet Effect in Magnetization Reversal of Stoner Particles: A new strategy is proposed aimed at substantially reducing the minimal\nmagnetization switching field for a Stoner particle. Unlike the normal method\nof applying a static magnetic field which must be larger than the magnetic\nanisotropy, a much weaker field, proportional to the damping constant in the\nweak damping regime, can be used to switch the magnetization from one state to\nanother if the field is along the motion of the magnetization. The concept is\nto constantly supply energy to the particle from the time-dependent magnetic\nfield to allow the particle to climb over the potential barrier between the\ninitial and the target states."
    },
    {
        "anchor": "Can CF(3)-functionalized La@C(60) be isolated experimentally and become\n  superconducting?: Superconducting behavior even under harsh ambient conditions is expected to\noccur in La@C(60) if it could be isolated from the primary metallofullerene\nsoot when functionalized by CF(3) radicals. We use ab initio density functional\ntheory calculations to compare the stability and electronic structure of C(60)\nand the La@C(60) endohedral metallofullerene to their counterparts\nfunctionalized by CF(3). We found that CF(3) radicals favor binding to C(60)\nand La@C(60), and have identified the most stable isomers. Structures with an\neven number m of radicals are energetically preferred for C(60) and structures\nwith odd m for La@C(60) due to the extra charge on the fullerene. This is\nconsistent with a wide HOMO-LUMO gap in La@C(60)(CF(3))(m) with odd m, causing\nextra stabilization in the closed-shell electronic configuration. CF(3)\nradicals are both stabilizing agents and molecular separators in a metallic\ncrystal, which could increase the critical temperature for superconductivity.",
        "positive": "Photoluminescence Study of Carbon Nanotubes: ultiwalled carbon nanotubes, prepared by both electric arc discharge and\nchemical vapor deposition methods, show a strong visible light emission in\nphotoluminescence experiments. All the samples employed in the experiments\nexhibit nearly same super-linear intensity dependence of the emission bands on\nthe excitation intensity, and negligible temperature dependence of the central\nposition and the line shapes of the emission bands. Based upon theoretical\nanalysis of the electronic band structures and optical transition, it is\nsuggested that besides the electronic transitions across the fundamental gap,\nthe transitions between pi and sigma conduction bands are the major source of\nthe light emissions. A two-step transition mechanism is proposed."
    },
    {
        "anchor": "Vibrational effects in x-ray absorption (XAS) and resonant inelastic\n  x-ray scattering (RIXS) using a semiclassical scheme: A new method is presented for describing vibrational effects in x-ray\nabsorption spectroscopy (XAS) and resonant inelastic x-ray scattering (RIXS)\nusing a combination of the classical Franck-Condon (FC) approximation and\nclassical trajectories run on the core-excited state. The formulation of RIXS\nis an extension of the semiclassical Kramers-Heisenberg (SCKH) formalism of\nRef. {Ljungberg_2010} to the resonant case, retaining approximately the same\ncomputational cost. To overcome difficulties with connecting the absorption and\nemission processes in RIXS the classical FC approximation is used for the\nabsorption, which is seen to work well provided that a zero-point-energy\ncorrection is included.\n  In the case of core-excited states with dissociative character the method is\ncapable of closely reproducing the main features for one-dimensional test\nsystems, compared to the quantum mechanical formulation. Due to the good\naccuracy combined with the relatively low computational cost, the method has\nlarge potential of being used for complex systems with many degrees of freedom,\nsuch as liquids and surface adsorbates.",
        "positive": "Solitons in the Crossover between Band Insulator and Mott Insulator:\n  Application to TTF-Chloranil under Pressure: Based on the Phase Hamiltonian, two types of solitons are found to exist in\nthe crossover region between band insulator and Mott insulator in\none-dimension. Both of these solitons have fractional charges but with\ndifferent spins, zero and 1/2, respectively. The results are in accord with the\nexperimental results by Kanoda et al. for TTF-Chloranil under pressure."
    },
    {
        "anchor": "Surface state at $BaSnO_3$ evidenced by angle-resolved photoemission\n  spectroscopy and ab initio calculations: Perovskite alkaline earth stannates, such as $BaSnO_3$ and $SrSnO_3$, showing\nlight transparency and high electrical conductivity (when doped), have become\npromising candidates for novel optoelectrical devices. Such devices are mostly\nbased on hetero-structures and understanding of their electronic structure,\nwhich usually deviates from the bulk, is mandatory for exploring a full\napplication potential. Employing angle-resolved photoemission spectroscopy and\nab initio calculations we reveal the existence of a 2-dimensional metallic\nstate at the $SnO_2$-terminated surface of a 1\\% La-doped $BaSnO_3$ thin film.\nThe observed surface state is characterized by distinct carrier density and a\nsmaller effective mass in comparison with the corresponding bulk values. The\nsmall surface effective mass of about $0.12m_e$ can cause an improvement of the\nelectrical conductivity of BSO based heterostructures.",
        "positive": "Electronic and vibrational spectroscopy of miscible MgO-ZnO ternary\n  alloys: The ordered structure of MgO-ZnO alloy system is a versatile tunable optical\nmaterial promising for diverse optoelectronic applications. However, isovalent\nand isostructural alloy compositions of MgO-ZnO are generally unstable at\nambient conditions. Using state-of-the-art \\textit{ab initio} evolutionary\nsimulations, we predict and study the properties of stable phases of MgO-ZnO.\nWe establish the dynamical stability of the predicted crystal structures\nthrough the phonon and Raman spectroscopy. Detailed analyses of two of the most\nstable structures reveal highly tunable properties that could be explored for\nphotonic and optical applications."
    },
    {
        "anchor": "Critical exponents of the order parameter of diffuse ferroelectric phase\n  transitions in the solid solutions based on lead germanate: studies of\n  optical rotation: In this work we show that the critical exponents of the order parameter\n(CEOPs) of diffuse ferroelectric phase transitions (DFEPTs) occurring in lead\ngermanate-based crystals can be determined using experimental temperature\ndependences of their optical rotation. We also describe the approach that\nsuggests dividing a crystal sample into many homogeneous unit cells, each of\nwhich is characterized by a non-diffuse phase transition with a specific local\nCurie temperature. Using this approach, the CEOPs have been determined for the\npure Pb$_{5}$Ge$_{3}$O$_{11}$ crystals, the solid solutions\nPb$_{5}$(Ge$_{1-x}$Si$_{x}$)$_{3}$O$_{11}$ ($x = $0.03, 0.05, 0.10, 0.20, 0.40)\nand (Pb$_{1-x}$Ba$_{x}$)$_{5}$Ge$_{3}$O$_{11}$ ($x =$ 0.02, 0.05), and the\ndoped crystals Pb$_{5}$Ge$_{3}$O$_{11}$:Li$^{3+}$ (0.005 wt. %),\nPb$_{5}$Ge$_{3}$O$_{11}$:La$^{3+}$ (0.02 wt. %),\nPb$_{5}$Ge$_{3}$O$_{11}$:Eu$^{3+}$ (0.021 wt. %),\nPb$_{5}$Ge$_{3}$O$_{11}$:Li$^{3+}$, Bi$^{3+}$ (0.152 wt.~\\%) and\nPb$_{5}$Ge$_{3}$O$_{11}$:Cu$^{2+}$ (0.14 wt. %). Comparison of our approach\nwith the other techniques used for determining the Curie temperatures and the\nCEOPs of DFEPTs testifies to its essential advantages.",
        "positive": "Complex magnetic textures in Ni/Ir$_{n}$/Pt(111) ultrathin films: A combined approach using first-principles calculations and spin dynamics\nsimulations is applied to study Ni/Ir$_{n}$/Pt(111) ($n=0,1,2$) films. The\nlowest-energy states are predicted to be spin-spirals but with a minute (of the\norder of a few $\\mu$eV/atom) energy difference with skyrmionic states. The\nspontaneous low temperature skyrmions, with $\\sim15$ nm to $\\sim35$ nm size,\narise from a large Dzyaloshinskii-Moriya (DM) and Heisenberg exchange\ninteractions ratio and, in particular, from a large in-plane DM vector\ncomponent for nearest neighbors. The skyrmions become larger and more dispersed\nwith the enhancement of the Ir buffer thickness. Also, with increasing $n$, the\nskyrmions stability decrease when an external magnetic field is applied or the\ntemperature is raised. For $n=0$ and $n=1$, we found that metastable\nskyrmioniums can occur, which are characterized by a slightly lower stability\nwith respect to the external fields and larger critical currents, compared to\nskyrmions."
    },
    {
        "anchor": "Noise influence on electron dynamics in semiconductors driven by a\n  periodic electric field: Studies about the constructive aspects of noise and fluctuations in different\nnon-linear systems have shown that the addition of external noise to systems\nwith an intrinsic noise may result in a less noisy response. Recently, the\npossibility to reduce the diffusion noise in semiconductor bulk materials by\nadding a random fluctuating contribution to the driving static electric field\nhas been tested. The present work extends the previous theories by considering\nthe noise-induced effects on the electron transport dynamics in low-doped\nn-type GaAs samples driven by a high-frequency periodic electric field\n(cyclostationary conditions). By means of Monte Carlo simulations, we calculate\nthe changes in the spectral density of the electron velocity fluctuations\ncaused by the addition of an external correlated noise source. The results\nreported in this paper confirm that, under specific conditions, the presence of\na fluctuating component added to an oscillating electric field can reduce the\ntotal noise power. Furthermore, we find a nonlinear behaviour of the spectral\ndensity with the noise intensity. Our study reveals that, critically depending\non the external noise correlation time, the dynamical response of electrons\ndriven by a periodic electric field receives a benefit by the constructive\ninterplay between the fluctuating field and the intrinsic noise of the system.",
        "positive": "Comment on \"Bound states of edge dislocations: The quantum dipole\n  problem in two dimensions\": We show that the numerical results contained in a recent paper are affected\nby a non optimal implementation of the methods which have been used to obtain\nthese results. A careful analysis done using the Rayleigh-Ritz method provides\na rigorous upper bound for the energy of the ground state of an electron in a\ntwo dimensional potential generated by the edge dislocation, as well as precise\nvalues for the excited states. The extrapolation of the results corresponding\nto different subspaces is used to obtain a precise estimate of the fundamental\nenergy of the model. The energies of the first 500 states that we have\ncalculated are in perfect agreement with the expected asymptotic behavior."
    },
    {
        "anchor": "Energy dissipation from confined states in nanoporous molecular networks: Crystalline nanoporous molecular networks are assembled on the Ag(111)\nsurface, where the pores confine electrons originating from the surface state\nof the metal. Depending on the pore sizes and their coupling, an antibonding\nlevel is shifted upwards by 0.1 to 0.3 eV as measured by scanning tunneling\nmicroscopy. On molecular sites, a down-shifted bonding state is observed, which\nis occupied under equilibrium conditions. Low-temperature force spectroscopy\nreveals energy dissipation peaks and jumps of frequency shifts at bias\nvoltages, which are related to the confined states. The dissipation maps show\ndelocalization on the supra-molecular assembly and a weak distance-dependence\nof the dissipation peaks. These observations indicate that two-dimensional\narrays of coupled quantum dots are formed, which are quantitatively\ncharacterized by their quantum capacitances and resonant tunneling rates. Our\nwork provides a method for studying the capacitive and dissipative response of\nquantum materials with nanomechanical oscillators.",
        "positive": "Electronic Structure of FeAl Alloy Studied by Resonant Photoemission\n  Spectroscopy and Ab Initio Calculations: Resonant photoemission spectroscopy has been used to investigate the\ncharacter of Fe 3d states in FeAl alloy. Fe 3d states have two different\ncharacter, first is of itinerant nature located very close to the Fermi level,\nand second, is of less itinerant (relatively localized character), located\nbeyond 2 eV below the Fermi level. These distinct states are clearly\ndistinguishable in the resonant photoemission data. Comparison between the\nresults obtained from experiments and first principle based electronic\nstructure calculation show that the origin of the itinerant character of the Fe\n3d states is due to the ordered B2 structure, whereas the relatively less\nitinerant (localized) Fe 3d states are from the disorders present in the\nsample. The exchange splitting of the Fe 3s core level peak confirms the\npresence of local moment in this system. It is found that the itinerant\nelectrons arise due to the hybridization between Fe 3d and Al 3s-3p states.\nPresence of hybridization is observed as a shift in the Al 2p core-level\nspectra as well as in the X-ray near edge absorption spectra towards lower\nbinding energy. Our photoemission results are thus explained by the\nco-existence of ordered and disordered phases in the system."
    },
    {
        "anchor": "Capacitance characterization of Graphene/n-Si Schottky junction solar\n  cell with MOS capacitor: We have demonstrated a simple and accurate method for characterizing the\ncapacitance of Graphene/n-Si Schottky junction solar cells (GSSCs) which embed\nthe metal-oxide-semiconductor (MOS) capacitor. We measured two types of GSSCs,\none with thermal annealing treatments (w-a) and one without (wo-a). It was\nfound that the wo-a GSSC exhibits a two-step feature in the phase versus\nforward bias voltage relationship, which may be attributed to the presence of\npolymethyl methacrylate residues. By considering the capacitance of the MOS\ncapacitor (Cmos) and its standard deviation, we successfully obtained the\ncapacitance of the Schottky junction (CSch), and evaluated meaningful built-in\npotentials (Schottky barrier heights) which are 0.51V (0.78eV) and 0.47V\n(0.75eV) for the w-a and wo-a GSSCs, respectively, by the Mott-Schottky\nanalysis. We also briefly discuss the relationship between CSch and the Nyquist\nand Bode plots, finding that the RC time constant decreases due to the\nsubtraction of Cmos.",
        "positive": "Properties of atomic intercalated carbon K4 crystals: The stability of atomic intercalated carbon $K_{4}$ crystals, XC$_{2}$ (X=H,\nLi, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ga, Ge, As, Se, Br, Rb\nor Sr) is evaluated by geometry optimization and frozen phonon analysis based\non first principles calculations. Although C $K_{4}$ is unstable, NaC$_{2}$ and\nMgC$_{2}$ are found to be stable. It is shown that NaC$_{2}$ and MgC$_{2}$ are\nmetallic and semi conducting, respectively."
    },
    {
        "anchor": "Selectivity in Ligand Functionalization of Photocatalytic Metal Oxide\n  Nanoparticles for Phase Transfer and Self-assembly Applications: Functionalization of photocatalytic metal oxide nanoparticles of TiO2, ZnO,\nWO3 and CuO with amine-terminated (oleylamine) and thiol-terminated\n(1-dodecanethiol) alkyl chained ligands was studied under ambient conditions. A\nhigh selectivity was observed in the binding specificity of a ligand towards\nnanoparticles of these different oxides. It was observed that oleylamine binds\nstably to only TiO2 and WO3, while 1-dodecanethiol binds stably only to ZnO and\nCuO. Similarly, polar to non-polar solvent phase transfer of TiO2 and WO3\nnanoparticles could be achieved by using oleylamine, but not by\n1-dodecanethiol, while the contrary holds for ZnO and CuO. The surface\nchemistry of ligand functionalized nanoparticles was probed by ATR-FTIR\nspectroscopy, that enabled to elucidate the occupation of the ligands at the\nactive sites. The photo-stability of the ligands on the nanoparticle surface\nwas determined by the photocatalytic self-cleaning properties of the material.\nWhile TiO2 and WO3 degrade the ligands within 24 hours under both UV and\nvisible light, ligands on ZnO and CuO remain unaffected. The gathered insights\nare also highly relevant from an application point of view. As an example,\nsince the ligand functionalized nanoparticles are hydrophobic in nature, they\ncan thus be self-assembled at the air-water interface, for obtaining\nnanoparticle films with demonstrated photocatalytic as well as anti-fogging\nproperties.",
        "positive": "Understanding the Influence of Receptive Field and Network Complexity in\n  Neural-Network-Guided TEM Image Analysis: Trained neural networks are promising tools to analyze the ever-increasing\namount of scientific image data, but it is unclear how to best customize these\nnetworks for the unique features in transmission electron micrographs. Here, we\nsystematically examine how neural network architecture choices affect how\nneural networks segment, or pixel-wise separate, crystalline nanoparticles from\namorphous background in transmission electron microscopy (TEM) images. We focus\non decoupling the influence of receptive field, or the area of the input image\nthat contributes to the output decision, from network complexity, which\ndictates the number of trainable parameters. We find that for low-resolution\nTEM images which rely on amplitude contrast to distinguish nanoparticles from\nbackground, the receptive field does not significantly influence segmentation\nperformance. On the other hand, for high-resolution TEM images which rely on a\ncombination of amplitude and phase contrast changes to identify nanoparticles,\nreceptive field is a key parameter for increased performance, especially in\nimages with minimal amplitude contrast. Our results provide insight and\nguidance as to how to adapt neural networks for applications with TEM datasets."
    },
    {
        "anchor": "Magnetic instabilities in doped Fe$_2YZ$ full-Heusler thermoelectric\n  compounds: Thermoelectricity is a promising avenue for harvesting energy but large-scale\napplications are still hampered by the lack of highly-efficient low-cost\nmaterials. Recently, Fe$_2YZ$ Heusler compounds were predicted theoretically to\nbe interesting candidates with large thermoelectric power factor. Here, we show\nthat under doping conditions compatible with thermoelectric applications, these\nmaterials are prone to an unexpected magnetic instability detrimental to their\nthermoelectric performance. We rationalize the physics at the origin of this\ninstability, provide guidelines for avoiding it and discuss its impact on the\nthermoelectric power factor. Doing so, we also point out the shortcomings of\nthe rigid band approximation commonly used in high-throughput theoretical\nsearches of new thermoelectrics.",
        "positive": "Atomistic Study of Irradiation-Induced Plastic and Lattice Strain in\n  Tungsten: We demonstrate a practical way to perform decomposition of the elasto-plastic\ndeformation directly from atomistic simulation snapshots. Through molecular\ndynamics simulations on a large single crystal, we elucidate the intricate\nprocess of converting plastic strain, atomic strain, and rigid rotation during\nirradiation. Our study highlights how prismatic dislocation loops act as\ninitiators of plastic strain effects in heavily irradiated metals, resulting in\nexperimentally measurable alterations in lattice strain. We show the onset of\nplastic strain starts to emerge at high dose, leading to the spontaneous\nemergence of dislocation creep and irradiation-induced lattice swelling. This\nphenomenon arises from the agglomeration of dislocation loops into a\ndislocation network. Furthermore, our numerical framework enables us to\ncategorize the plastic transformation into two distinct types: pure slip events\nand slip events accompanied by lattice swelling. The latter type is\nparticularly responsible for the observed divergence in interstitial and\nvacancy counts, and also impacts the behavior of dislocations, potentially\nactivating non-conventional slip systems."
    },
    {
        "anchor": "Charge density wave induced nodal lines in LaTe$_3$: LaTe$_3$ is a noncentrosymmetric (NC) material with time reversal (TR)\nsymmetry in which the charge density wave (CDW) is hosted by the Te bilayers.\nHere, we show that LaTe$_3$ hosts a Kramers nodal line (KNL), a twofold\ndegenerate nodal line that connects the TR invariant momenta in NC achiral\nsystems, using angle resolved photoemission spectroscopy (ARPES), density\nfunctional theory (DFT), effective band structure (EBS) calculated by band\nunfolding, and symmetry arguments. DFT incorporating spin-orbit coupling (SOC)\nreveals that the KNL -- protected by the TR and lattice symmetries -- imposes\ngapless crossings between the bilayer-split CDW-induced shadow bands and the\nmain bands. In excellent agreement with the EBS, ARPES data corroborate the\npresence of the KNL and show that the crossings traverse the Fermi level.\nFurthermore, spinless nodal lines - entirely gapped out by the SOC - are formed\nby the linear crossings of the shadow and main bands with a high Fermi\nvelocity.",
        "positive": "Magneto-transport studies on (Pr1/3Sm2/3)2/3A1/3MnO3 (A = Ca, Sr and Ba)\n  compounds: Magnetic and transport properties of (Pr1/3Sm2/3)2/3A1/3MnO3 (A = Ca, Sr and\nBa) compounds, prepared by the citrate gel route, have been investigated. These\ncompounds are found to crystallize in the orthorhombic structure. Charge\nordering transport behavior is indicated only in Ca-substituted compound. The\nSr- and Ba-substituted compounds show metal-insulator transition and\nsemiconducting-like behavior, respectively. The magnetoresistance is highest in\nthe Ba substituted compound. All the three samples show irreversibility in\nmagnetization as a function of temperature in zero-field cooled (ZFC) and field\ncooled (FC) plots. The non-saturating magnetization, even at 5K and 4 Tesla\nfield, are observed in Ca as well Ba-substituted compounds."
    },
    {
        "anchor": "Optical characterization of GaN by N+ implantation into GaAs at elevated\n  temperature: Both hexagonal wurtzite and cubic zinc blend GaN phases were synthesized in\nGaAs by 50 keV N+ implantation at 400 deg C and subsequent annealing at 900 deg\nC for 15 min in N2 ambient. Crystallographic structural and Raman scattering\nstudies revealed that GaN phases were grown for fluence above 2x1017 cm-2.\nTemperature-dependent photoluminescence study showed sharp direct band-to-band\ntransition peak ~3.32 eV at temperature <= 200K. The intermediate bandgap\nvalue, with respect to ~3.4 eV for hexagonal and ~3.27 eV for cubic phases of\nGaN is an indicative for the formation of mixed hexagonal and cubic phases.",
        "positive": "Dense and single-phase KTaO$_{3}$ ceramics obtained by spark plasma\n  sintering: Potassium tantalate (KTaO$_{3}$) is a promising material for dielectric\napplications at low temperature. However, dense and single-phase ceramics\ncannot be obtained by conventional sintering because of the evaporation of\npotassium that leads to secondary phases. Here, we demonstrate that spark\nplasma sintering is a suitable method to obtain dense and single-phase\nKTaO$_{3}$ ceramics, by optimizing three parameters: initial composition,\ntemperature, and pressure. A 2 mol% K-excess in the precursors leads to a large\ngrain growth and dense single-phase ceramics. Without K-excess, a small amount\nof secondary phase (K$_{6}$Ta$_{10.8}$O$_{30}$) is observed at the surface but\ncan be removed by polishing. At 10 K, the dielectric permittivity is 4 times\nhigher in the ceramic from the 2 mol% K-excess powder, because of the larger\ngrain size. The thermal conductivity decreases with decreasing grain size and\nstays above the thermal conductivity of KNbO$_{3}$ ceramics."
    },
    {
        "anchor": "Lattice Green's function for crystals containing a planar interface: Flexible boundary condition methods couple an isolated defect to a\nharmonically responding medium through the bulk lattice Green's function; in\nthe case of an interface, interfacial lattice Green's functions. We present a\nmethod to compute the lattice Green's function for a planar interface with\narbitrary atomic interactions suited for the study of line defect/interface\ninteractions. The interface is coupled to two different semi-infinite bulk\nregions, and the Green's function for interface-interface, bulk-interface and\nbulk-bulk interactions are computed individually. The elastic bicrystal Green's\nfunction and the bulk lattice Green's function give the interaction between\nbulk regions. We make use of partial Fourier transforms to treat in-plane\nperiodicity. Direct inversion of the force constant matrix in the partial\nFourier space provides the interface terms. The general method makes no\nassumptions about the atomic interactions or crystal orientations. We simulate\na screw dislocation interacting with a $(10\\bar{1}2)$ twin boundary in Ti using\nflexible boundary conditions and compare with traditional fixed boundary\nconditions results. Flexible boundary conditions give the correct core\nstructure with significantly less atoms required to relax by energy\nminimization. This highlights the applicability of flexible boundary conditions\nmethods to modeling defect/interface interactions by \\textit{ab initio}\nmethods.",
        "positive": "A possible source of spin-polarized electrons: The inert\n  graphene/Ni(111) system: We report on an investigation of spin-polarized secondary electron emission\nfrom the chemically inert system: graphene/Ni(111). An ordered passivated\ngraphene layer (monolayer of graphite, MG) was formed on Ni(111) surface via\ncracking of propylene gas. The spin-polarization of the secondary electrons\nobtained from this system upon photoemission is only slightly lower than the\none from the clean Ni surface, but does not change upon large oxygen exposure.\nThese results suggest to use such passivated Ni(111) surface as a source of\nspin-polarized electrons stable against adsorption of reactive gases."
    },
    {
        "anchor": "Hall effect of quasi-hole gas in organic single-crystal transistors: Hall effect is detected in organic field-effect transistors, using\nappropriately shaped rubrene (C42H28) single crystals. It turned out that\ninverse Hall coefficient, having a positive sign, is close to the amount of\nelectric-field induced charge upon the hole accumulation. The presence of the\nnormal Hall effect means that the electromagnetic character of the surface\ncharge is not of hopping carriers but resembles that of a two-dimensional\nhole-gas system.",
        "positive": "On the effects of transformation strain induced by hydride precipitation: One of the main degradation mechanisms of the zirconium alloys used in\nnuclear reactors is hydrogen embrittlement and hydride formation. The formation\nof zirconium hydrides is accompanied by a transformation strain, the effects of\nwhich on the development of localized deformation zones are not\nwell-understood. This study uses a crystal plasticity finite element model that\nis coupled with diffusion subroutines to quantify such effects. For this\npurpose, a zirconium specimen was hydrided in the absence of any external\nmechanical loads. With the use of electron backscatter diffraction, the\nrotation fields around interacting intragranular hydrides as well as those\nlocated at grain boundaries or triple points were measured at a high spatial\nresolution. The as-measured zirconium and hydride morphologies were mapped to\nthe model for numerical simulation. Both numerical and experimental results\nshow that hydride precipitation induces large rotation fields within the\nzirconium matrix, where such rotations are at their maximum in the vicinity of\nhydride tips. While the crystallographic orientations and shapes of hydrides\naffect the magnitude of rotation fields, both experimental and modeling results\nrevealed the development of discrete and parallel geometrically necessary\ndislocation fields and a strong interaction among neighboring hydrides. It is\nshown that the stress field resulting from hydride precipitation affects the\npatterning of hydrogen distribution, which in return affects further hydride\ninterlinking."
    },
    {
        "anchor": "The Effect of Cesium Carbonate on PCBM Aggregation in Films: Surface-pressure isotherms, X-ray reflectivity and X-ray near-total\nreflection fluorescence were used to study the properties of\n1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]C$_{61}$ (PCBM) that was pre-mixed\nwith cesium carbonate and spread as a film at the air-water interface. The\npre-mixed PCBM with cesium carbonate demonstrated a strikingly strong effect on\nthe organization of the film. Whereas films formed from pure PCBM solution were\nrough due to strong inter-molecular interactions, the films formed from the\nmixture were much smoother. This indicates that the cesium carbonate moderates\nthe inter-molecular interactions among PCBM molecules, hinting that the cesium\ndiffusion observed in inverted organic photovoltaics and the likely ensuing\nionic Cs-PCBM interaction decreases aggregation tendency of PCBM. This implies\nthat the use of cesium salts affects the morphology of the organic layer and\nconsequently improves the efficiency of these devices.",
        "positive": "Porosity dependence of powder compaction constitutive parameters:\n  Determination based on spark plasma sintering tests: The modeling of powder compaction process, such as spark plasma sintering\n(SPS), requires the determination of the visco-plastic deformation behavior of\nthe particle material including the viscosity moduli. The establishment of\nthese parameters usually entails a long and difficult experimental campaign\nwhich in particular involves several hot isostatic pressing tests. A more\nstraightforward method based on the coupled sinter-forging and die compaction\ntests, which can be easily carried out in a regular SPS device, is presented.\nCompared to classical creep mechanism studies, this comprehensive experimental\napproach can reveal the in situ porous structure morphology influence on the\nsintering process."
    },
    {
        "anchor": "Electronic effects in radiation-induced collision cascades in nickel: The accurate treatment of electronic effects in multi-million atom\nsimulations of radiation-induced collision cascades is crucial for reliable\npredictions of primary radiation damage. In this work, we explore the\nperformance of a recently developed two-temperature molecular dynamics model\nimplementing an electron density-dependent coupling of electronic and atomic\nsubsystems for cascade simulations in nickel. We show that the parameter-free\nmodel realistically captures the instantaneous energy losses during all stages\nof the highly non-equilibrium cascade process. Simulations predict two distinct\ncoupling regimes, corresponding to the rapid electronic stopping energy losses\nin the early stages of the cascade and to the electron-phonon coupling\nmechanism in the later stages, without the use of separate coupling terms. The\nintermediate stage of the cascade dynamics displays a complex energy transfer\nbetween the subsystems, which cannot be validated by comparison to either\nelectronic stopping or electron-phonon coupling theories. We therefore compare\nthe predicted atomic mixing, which is sensitive to the energy losses during the\nintermediate cascade stage, with experimental ion beam mixing measurements. We\nfind good agreement with the experiments, validating the coupling model for the\nintermediate stage of cascades. Predictions of final defect numbers and cluster\nsizes are found in line with the predictions of conventional electronic\nstopping-based methods, while significantly reducing the theoretical\nuncertainty in the predictions of conventional models stemming from arbitrary\nchoices of thresholds for different coupling terms. Our results represent a\nnotable improvement in cascade damage predictions in nickel, providing\nvalidation of the electron density-dependent coupling model for radiation\ndamage simulations in general.",
        "positive": "Simultaneous Learning of Several Materials Properties from Incomplete\n  Databases with Multi-Task SISSO: The identification of descriptors of materials properties and functions that\ncapture the underlying physical mechanisms is a critical goal in data-driven\nmaterials science. Only such descriptors will enable a trustful and efficient\nscanning of materials spaces and possibly the discovery of new materials.\nRecently, the sure-independence screening and sparsifying operator (SISSO) has\nbeen introduced and was successfully applied to a number of materials-science\nproblems. SISSO is a compressed-sensing based methodology yielding predictive\nmodels that are expressed in form of analytical formulas, built from simple\nphysical properties. These formulas are systematically selected from an immense\nnumber (billions or more) of candidates. In this work, we describe a powerful\nextension of the methodology to a 'multi-task learning' approach, which\nidentifies a single descriptor capturing multiple target materials properties\nat the same time. This approach is specifically suited for a heterogeneous\nmaterials database with scarce or partial data, e.g., in which not all\nproperties are reported for all materials in the training set. As showcase\nexamples, we address the construction of materials-properties maps for the\nrelative stability of octet-binary compounds, considering several crystal\nphases simultaneously, and the metal/insulator classification of binary\nmaterials distributed over many crystal-prototypes."
    },
    {
        "anchor": "Large area and structured epitaxial graphene produced by confinement\n  controlled sublimation of silicon carbide: After the pioneering investigations into graphene-based electronics at\nGeorgia Tech (GT), great strides have been made developing epitaxial graphene\non silicon carbide (EG) as a new electronic material. EG has not only\ndemonstrated its potential for large scale applications, it also has become an\ninvaluable material for fundamental two-dimensional electron gas physics\nshowing that only EG is on route to define future graphene science. It was long\nknown that graphene mono and multilayers grow on SiC crystals at high\ntemperatures in ultra-high vacuum. At these temperatures, silicon sublimes from\nthe surface and the carbon rich surface layer transforms to graphene. However\nthe quality of the graphene produced in ultrahigh vacuum is poor due to the\nhigh sublimation rates at relatively low temperatures. The GT team developed\ngrowth methods involving encapsulating the SiC crystals in graphite enclosures,\nthereby sequestering the evaporated silicon and bringing growth process closer\nto equilibrium. In this confinement controlled sublimation (CCS) process, very\nhigh quality graphene is grown on both polar faces of the SiC crystals. Since\n2003, over 50 publications used CCS grown graphene, where it is known as the\n\"furnace grown\" graphene. Graphene multilayers grown on the carbon-terminated\nface of SiC, using the CCS method, were shown to consist of decoupled high\nmobility graphene layers. The CCS method is now applied on structured silicon\ncarbide surfaces to produce high mobility nano-patterned graphene structures\nthereby demonstrating that EG is a viable contender for next-generation\nelectronics. Here we present the CCS method and demonstrate several of\nepitaxial graphene's outstanding properties and applications.",
        "positive": "Computational Design of Nanoclusters by Property-Based Genetic\n  Algorithms: Tuning the Electronic Properties of (TiO$_2$)$_n$ Clusters: In order to design clusters with desired properties, we have implemented a\nsuite of genetic algorithms tailored to optimize for low total energy, high\nvertical electron affinity (VEA), and low vertical ionization potential (VIP).\nApplied to (TiO$_2$)$_n$ clusters, the property-based optimization reveals the\nunderlying structure-property relations and the structural features that may\nserve as active sites for catalysis. High VEA and low VIP are correlated with\nthe presence of several dangling-O atoms and their proximity, respectively. We\nshow that the electronic properties of (TiO$_2$)$_n$ up to n=20 correlate more\nstrongly with the presence of these structural features than with size."
    },
    {
        "anchor": "Pressure-induced amorphization, crystal-crystal transformations and the\n  memory glass effect in interacting particles in two dimensions: We study a model of interacting particles in two dimensions to address the\nrelation between crystal-crystal transformations and pressure-induced\namorphization. On increasing pressure at very low temperature, our model\nundergoes a martensitic crystal-crystal transformation. The characteristics of\nthe resulting polycrystalline structure depend on defect density, compression\nrate, and nucleation and growth barriers. We find two different limiting cases.\nIn one of them the martensite crystals, once nucleated, grow easily\nperpendicularly to the invariant interface, and the final structure contains\nlarge crystals of the different martensite variants. Upon decompression almost\nevery atom returns to its original position, and the original crystal is fully\nrecovered. In the second limiting case, after nucleation the growth of\nmartensite crystals is inhibited by energetic barriers. The final morphology in\nthis case is that of a polycrystal with a very small crystal size. This may be\ntaken to be amorphous if we have only access (as experimentally may be the\ncase) to the angularly averaged structure factor. However, this `X-ray\namorphous' material is anisotropic, and this shows up upon decompression, when\nit recovers the original crystalline structure with an orientation correlated\nwith the one it had prior to compression. The memory effect of this X-ray\namorphous material is a natural consequence of the memory effect associated to\nthe underlying martensitic transformation. We suggest that this kind of\nmechanism is present in many of the experimental observations of the memory\nglass effect, in which a crystal with the original orientation is recovered\nfrom an apparently amorphous sample when pressure is released.",
        "positive": "Criteria for accurate determination of the magnon relaxation length from\n  the nonlocal spin Seebeck effect: The nonlocal transport of thermally generated magnons not only unveils the\nunderlying mechanism of the spin Seebeck effect, but also allows for the\nextraction of the magnon relaxation length ($\\lambda_m$) in a magnetic\nmaterial, the average distance over which thermal magnons can propagate. In\nthis study, we experimentally explore in yttrium iron garnet (YIG)/platinum\nsystems much further ranges compared with previous investigations. We observe\nthat the nonlocal SSE signals at long distances ($d$) clearly deviate from a\ntypical exponential decay. Instead, they can be dominated by the nonlocal\ngeneration of magnon accumulation as a result of the temperature gradient\npresent away from the heater, and decay geometrically as $1/d^2$. We emphasize\nthe importance of looking only into the exponential regime (i.e., the\nintermediate distance regime) to extract $\\lambda_m$. With this principle, we\nstudy $\\lambda_m$ as a function of temperature in two YIG films which are 2.7\nand 50 $\\mu$m in thickness, respectively. We find $\\lambda_m$ to be around 15\n$\\mu$m at room temperature and it increases to 40 $\\mu$m at $T=$ 3.5 K. Finite\nelement modeling results agree with experimental studies qualitatively, showing\nalso a geometrical decay beyond the exponential regime. Based on both\nexperimental and modeling results we put forward a general guideline for\nextracting $\\lambda_m$ from the nonlocal spin Seebeck effect."
    },
    {
        "anchor": "Quantum anomalous Hall effect in stable 1T-YN$_2$ monolayer with a large\n  nontrivial band gap and high Chern number: The quantum anomalous Hall (QAH) effect is a topologically nontrivial phase,\ncharacterized by a non-zero Chern number defined in the bulk and chiral edge\nstates in the boundary. Using first-principles calculations, we demonstrate the\npresence of the QAH effect in 1T-YN$_2$ monolayer, which was recently predicted\nto be a Dirac half metal without spin-orbit coupling (SOC). We show that the\ninclusion of SOC opens up a large nontrivial band gap of nearly $0.1$ eV in the\nelectronic band structure. This results in the nontrivial bulk topology which\nis confirmed by the calculation of Berry curvature, anomalous Hall conductance\nand the presence of chiral edge states. Remarkably, a high Chern number $C = 3$\nis found, and there are three corresponding gapless chiral edge states emerging\ninside the bulk gap. Our results open a new avenue in searching for QAH\ninsulators with high temperature and high Chern numbers, which can have\nnontrivial practical applications.",
        "positive": "Delocalisation enables efficient charge generation in organic\n  photovoltaics, even with little to no energetic offset: Organic photovoltaics (OPVs) are promising candidates for solar-energy\nconversion, with device efficiencies continuing to increase. However, the\nprecise mechanism of how charges separate in OPVs is not well understood\nbecause low dielectric constants produce a strong attraction between the\ncharges, which they must overcome to separate. Separation has been thought to\nrequire energetic offsets at donor-acceptor interfaces, but recent materials\nhave enabled efficient charge generation with small offsets, or with none at\nall in neat materials. Here, we extend delocalised kinetic Monte Carlo (dKMC)\nto develop a three-dimensional model of charge generation that includes\ndisorder, delocalisation, and polaron formation in every step from\nphotoexcitation to charge separation. Our simulations show that delocalisation\ndramatically increases charge-generation efficiency, partly by enabling\nexcitons to dissociate in the bulk. Therefore, charge generation can be\nefficient even in devices with little to no energetic offset, including neat\nmaterials. Our findings demonstrate that the underlying quantum-mechanical\neffect that improves the charge-separation kinetics is faster and\nlonger-distance hops between delocalised states, mediated by hybridised states\nof exciton and charge-transfer character."
    },
    {
        "anchor": "Spin wave theory study of neutron intensity, magnetic field, and\n  anisotropy of Type IIA FCC antiferromagnet: We study the spin dynamics in a 3D quantum antiferromagnet on a face-centered\ncubic (FCC) lattice. The effects of magnetic field, single-ion anisotropy, and\nbiquadratic interactions are investigated using linear spin wave theory with\nspins in a canted basis about the Type IIA FCC antiferromagnetic ground state\nstructure which is known to be stable. We calculate the expected finite\nfrequency neutron scattering intensity and give qualitative criteria for\ntypical FCC materials MnO and CoO. The magnetization reduction due to quantum\nzero point fluctuations is also analyzed.",
        "positive": "Site-substitution in GdMnO3 : effects on structural, electronic and\n  magnetic properties: We report on detailed structural, electronic and magnetic studies of\nGdMn$_{1-x}$Cr$_x$O$_3$ for Cr doping levels 0 $\\le$ $x$ $\\le$ 1. In the solid\nsolutions, the Jahn-Teller distortion associated with Mn$^{3+}$ ions gives rise\nto major changes in the ${bc}$-plane sub-lattice and also the effective orbital\nordering in the ${ab}$-plane, which persist up to the compositions $x$ $\\sim$\n0.35. These distinct features in the lattice and orbital degrees of freedom are\nalso correlated with $bc$-plane anisotropy of the local Gd environment. A\ngradual evolution of electronic states with doping is also clearly seen in O\n$K$-edge x-ray absorption spectra. Evidence of magnetization reversal in\nfield-cooled-cooling mode for $x$ $\\ge$ 0.35 coinciding the Jahn-Teller\ncrossover, suggests a close correlation between magnetic interaction and\nstructural distortion. These observations indicate a strong entanglement\nbetween lattice, spin, electronic and orbital degrees of freedom. The\nnonmonotonic variation of remnant magnetization can be explained by doping\ninduced modification of magnetic interactions. Density functional theory\ncalculations are consistent with a layer-by-layer type doping with\nferromagnetic (antiferomagnetic) coupling between Mn (Cr) ions for intermediate\ncompound ($x$ = 0.5), which is distinct from that observed for the end members\nGMnO$_3$ and GdCrO$_3$."
    },
    {
        "anchor": "Coverage Dependence of the Level Alignment for Methanol on TiO$_2$(110): Electronic level alignment at the interface between an adsorbed molecular\nlayer and a semiconducting substrate determines the activity and efficiency of\nmany photocatalytic materials. We perform $G_0W_0$ calculations to determine\nthe coverage dependence of the level alignment for a prototypical\nphotocatalytic interface: 1/2 and 1 monolayer (ML) intact and dissociated\nCH$_3$OH on rutile TiO$_2$(110). We find changes in the wavefunction's spatial\ndistribution, and a consequent renormalization of the quasiparticle energy\nlevels, as a function of CH$_3$OH coverage and dissociation. Our results\nsuggest that the occupied molecular levels responsible for hole trapping are\nnot those observed in the ultraviolet photoemission spectroscopy (UPS)\nspectrum. Rather, they are those of isolated CH$_3$O on the surface. We find\nthe unoccupied molecular levels have either 2D character with weight above the\nsurface at 1 ML coverage, or significant hybridization with the surface at 1/2\nML coverage. These results suggest the resonance observed in the two photon\nphooemission (2PP) spectrum arises from excitations to unoccupied \"Wet\nelectron\" levels with 2D character.",
        "positive": "Stanene: A Good Platform for Topological Insulator and Topological\n  Superconductor: Two dimensional (2D) topological insulators (TIs) and topological\nsuperconductors (TSCs) have been intensively studied for recent years due to\nits great potential for dissipationless electron transportation and\nfault-tolerant quantum computing, respectively. Here we focus on stanene, the\ntin analogue of graphene, to give a brief review of its development as a\ncandidate for both 2D TI and TSC. Stanene is proposed to be a TI with a large\ngap of 0.3 eV, and its topological properties are sensitive to various factors,\ne.g., the lattice constants, chemical functionalization and layer thickness,\nwhich offer various methods for phase tunning. Experimentally, the inverted gap\nand edge states are observed recently, which are strong evidence for TI. In\naddition, stanene is also predicted to be a time reversal invariant TSC by\nbreaking inversion symmetry, supporting helical Majorana edge modes. The\nlayer-dependent superconductivity of stanene is recently confirmed by both\ntransport and scanning tunneling microscopy measurements. This review gives a\ndetailed introduction to stanene and its topological properties and some\nprospects are also discussed."
    },
    {
        "anchor": "A Laboratory-based Hard X-ray Monochromator for High-Resolution X-ray\n  Emission Spectroscopy and X-ray Absorption Near Edge Structure Measurements: We report the development of a laboratory-based Rowland-circle monochromator\nthat incorporates a low poer x-ray (bremsstrahlung) tube source, a\nspherically-bent crystal analyzer (SBCA), and an energy-resolving solid-state\ndetector. This relatively inexpensive, introductory level instrument achieves\n1-eV energy resolution for photon energies of 5 keV to 10 keV while also\ndmeonstrating a net efficiency previously seen only in laboratory\nmonochromators having much coarser energy resolution. Despite the use of only a\ncompact, air-cooled 10 W x-ray tube, we find count rates for nonresonant x-ray\nemission spectroscopy (XES) comparable to those achived at monochromatized\nspectroscopy beamlines at synchrotron light sources. For x-ray absorption near\nedge structure (XANES), the monochromatized flux is small (due to the use of a\nlow-powered x-ray generator) but still useful for routine transmission-mode\nstudies of concentrated samples. These results indicate that upgrading to a\nstandard commercial high-powered line-focused x-ray tube or rotating anode\nx-ray generator would result in monochromatized fluxes of order 10^6 to 10^7\nphotons/s with no loss in energy resolution. This work establishes core\ntechnical capabilities for a rejuvenation of laboratory-based x-ray\nspectroscopies that could have special relevance for contemporary research on\ncatalytic or electrical energy storage systems using transition-metal,\nlanthanide, or noble-metal active species.",
        "positive": "Evolution of Glassy Carbon Microstructure: In Situ Transmission Electron\n  Microscopy of the Pyrolysis Process: Glassy carbon is a graphene-rich form of elemental carbon obtained from\npyrolysis of polymers, which is composed of three-dimensionally arranged,\ncurved graphene fragments alongside fractions of disordered carbon and voids.\nPyrolysis encompasses gradual heating of polymers above 900 degree C under\ninert atmosphere, followed by cooling to room temperature. Here we report on an\nexperimental method to perform in situ high-resolution transmission electron\nmicroscopy (HR-TEM) for the direct visualization of microstructural evolution\nin a pyrolyzing polymer in the 500-1200 degree C temperature range. The results\nare compared with the existing microstructural models of glassy carbon.\nReported experiments are performed at 80 kV acceleration voltage using\nMEMS-based heating chips as sample substrates to minimize any undesired\nbeam-damage or sample preparation induced transformations. The outcome suggests\nthat the geometry, expansion and atomic arrangement within the resulting\ngraphene fragments constantly change, and that the intermediate structures\nprovide important cues on the evolution of glassy carbon. A complete\nunderstanding of the pyrolysis process will allow for a general process tuning\nspecific to the precursor polymer for obtaining glassy carbon with pre-defined\nproperties."
    },
    {
        "anchor": "Melting and Rippling Phenomenan in Two Dimensional Crystals with\n  localized bonding: We calculate Root Mean Square (RMS) deviations from equilibrium for atoms in\na two dimensional crystal with local (e.g. covalent) bonding between close\nneighbors. Large scale Monte Carlo calculations are in good agreement with\nanalytical results obtained in the harmonic approximation. When motion is\nrestricted to the plane, we find a slow (logarithmic) increase in fluctuations\nof the atoms about their equilibrium positions as the crystals are made larger\nand larger. We take into account fluctuations perpendicular to the lattice\nplane, manifest as undulating ripples, by examining dual layer systems with\ncoupling between the layers to impart local rigidly (i.e. as in sheets of\ngraphene made stiff by their finite thickness). Surprisingly, we find a rapid\ndivergence with increasing system size in the vertical mean square deviations,\nindependent of the strength of the interplanar coupling. We consider an\nattractive coupling to a flat substrate, finding that even a weak attraction\nsignificantly limits the amplitude and average wavelength of the ripples. We\nverify our results are generic by examining a variety of distinct geometries,\nobtaining the same phenomena in each case.",
        "positive": "Adsorption of Alkali, Alkaline Earth and Transition Metal Atoms on\n  Silicene: The adsorption characteristics of alkali, alkaline earth and transition metal\nadatoms on silicene, a graphene-like monolayer structure of silicon, are\nanalyzed by means of first-principles calculations. In contrast to graphene,\ninteraction between the metal atoms and the silicene surface is quite strong\ndue to its highly reactive buckled hexagonal structure. In addition to\nstructural properties, we also calculate the electronic band dispersion, net\nmagnetic moment, charge transfer, workfunction and dipole moment of the metal\nadsorbed silicene sheets. Alkali metals, Li, Na and K, adsorb to hollow site\nwithout any lattice distortion. As a consequence of the significant charge\ntransfer from alkalis to silicene metalization of silicene takes place. Trends\ndirectly related to atomic size, adsorption height, workfunction and dipole\nmoment of the silicene/alkali adatom system are also revealed. We found that\nthe adsorption of alkaline earth metals on silicene are entirely different from\ntheir adsorption on graphene. The adsorption of Be, Mg and Ca turns silicene\ninto a narrow gap semiconductor. Adsorption characteristics of eight transition\nmetals Ti, V, Cr, Mn, Fe, Co, Mo and W are also investigated. As a result of\ntheir partially occupied d orbital, transition metals show diverse structural,\nelectronic and magnetic properties. Upon the adsorption of transition metals,\ndepending on the adatom type and atomic radius, the system can exhibit metal,\nhalf-metal and semiconducting behavior. For all metal adsorbates the direction\nof the charge transfer is from adsorbate to silicene, because of its high\nsurface reactivity. Our results indicate that the reactive crystal structure of\nsilicene provides a rich playground for functionalization at nanoscale."
    },
    {
        "anchor": "Lattice dynamics and electronic structure of energetic solids LiN3 and\n  NaN3: A first principles study: We report density functional theory calculations on the crystal structure,\nelastic, lattice dynamics and electronic properties of iso-structural layered\nmonoclinic alkali azides, LiN3 and NaN3. The effect of van der Waals\ninteractions on the ground- state structural properties is studied by using\nvarious dispersion corrected density functionals. Based on the equilibrium\ncrystal structure, the elastic constants, phonon dispersion and phonon density\nof states of the compounds are calculated. The accurate energy band gaps are\nobtained by using the recently developed Tran Blaha-modified Becke Johnson\n(TB-mBJ) functional and found that both the azides are direct band gap\ninsulators.",
        "positive": "Effective Model for Fractional Topological Corner Modes in Quasicrystals: High-order topological insulators (HOTIs), as generalized from topological\ncrystalline insulators (TCIs), are characterized with lower-dimensional\nmetallic boundary states protected by spatial symmetries of a crystal, whose\ntheoretical framework based on band inversion at special $k$-points cannot be\nreadily extended to quasicrystals because quasicrystals contain rotational\nsymmetries that are not compatible with crystals, and momentum is no longer a\ngood quantum number. Here, we develop a low-energy effective model underlying\nHOTI states in 2D quasicrystals for all possible rotational symmetries. By\nimplementing a novel Fourier transform developed recently for quasicrystals and\napproximating the long-wavelength behavior by their large-scale average, we\nconstruct an effective $k \\cdot p$ Hamiltonian to capture the band inversion at\nthe center of a pseudo-Brillouin zone (PBZ). We show that an in-plane Zeeman\nfield can induce mass-kinks at the intersection of adjacent edges of a 2D\nquasicrystal TI and generate corner modes (CMs) with fractional charge,\nprotected by rotational symmetries. Our model predictions are confirmed by\nnumerical tight-binding calculations. Furthermore, when the quasicrystal is\nproximitized by an \\textit{s}-wave superconductor, Majorana CMs can also be\ncreated by tuning the field strength and chemical potential. Our work affords a\ngeneric approach to studying the low-energy physics of quasicrystals, in\nassociation with topological excitations and fractional statistics."
    },
    {
        "anchor": "Direct observation of domain wall structures in curved permalloy wires\n  containing an anti-notch: The formation and field response of head-to-head domain walls in curved\npermalloy wires, fabricated to contain a single anti-notch, have been\ninvestigated using Lorentz microscopy. High spatial resolution maps of the\nvector induction distribution in domain walls close to the anti-notch have been\nderived and compared with micromagnetic simulations. In wires of 10 nm\nthickness the walls are typically of a modified asymmetric transverse wall\ntype. Their response to applied fields tangential to the wire at the anti-notch\nlocation was studied. The way the wall structure changes depends on whether the\nfield moves the wall away from or further into the notch. Higher fields are\nneeded and much more distorted wall structures are observed in the latter case,\nindicating that the anti-notch acts as an energy barrier for the domain wall.",
        "positive": "Molecular dynamics simulations of surface modification formations on\n  polycrystalline Cu under high electric fields: Vacuum breakdowns in particle accelerators and other devices operating at\nhigh electric fields is a common problem in the operation of these devices. It\nhas been proposed that the onset of vacuum breakdowns is associated with\nappearance of surface protrusions while the device is in operation under high\nelectric field. Moreover, the breakdown tolerance of an electrode material was\ncorrelated with the type of lattice structure of the material. In the current\npaper we conduct molecular dynamics simulations of nanocrystalline copper\nsurfaces and show the possibility of protrusion growth under the stress exerted\non the surface by an applied electrostatic field. We show the importance of\ngrain boundaries on the protrusion formation and establish a linear\nrelationship between the necessary electrostatic stress for protrusion\nformation and the temperature of the system. We show that time for protrusion\nformation increases with the lowering electrostatic field and give the\nArrhenius extrapolation to the case of lower fields. General discussion of the\nprotrusion formation mechanisms in the case of polycrystalline copper surfaces\nis presented."
    },
    {
        "anchor": "Defect complex formation in TiO2 nanoparticles by sub-band excitation: Anatase TiO2 is an indirect band-gap material with large degree of\nsub-stoichiometry, selective excitation of its native defect reveals\npolychromatic emission in blue, green and red spectral regions due to self\ntrapped excitons and singlet-singlet transition of defect states. Electron spin\nresonance measurement in dark shows presence of isolated Ti+3, deep lying, and\nsurface lying VO at 1.986, 2.04 and 2.023 g values respectively, whereas , on\nexposure with visible light in situ ESR measurement reveals the formation of\ndefect complex of Ti+3-VO and Ti+4-V+O.",
        "positive": "Finite size and volume effects in line node semimetals: a\n  first-principles investigation: We systematically study the bulk and finite size effects on the band\nstructure of prototypical line node materials using density functional theory\nbased computations. For the bulk system, we analyze quantum oscillations with\nchanges in the Fermi surface topology. We show that ultra thin slabs are\ngapped, with the first signatures of the line node appearing beyond a critical\nthickness. Further, motivated by possibility of tuning the bulk line node, we\nfind that the line node radius is rather sensitive to bulk volume change. Based\non this observation, we propose that application of pressure or suitable\nsubstrate engineering can be used as an effective means to control and tune the\nline node and the accompanying surface drumhead states."
    },
    {
        "anchor": "Glass-like features of crystalline solids in the quantum critical regime: There has been growing interest in structural quantum phase transitions and\nquantum fluctuations of phonons in the research area of condensed matter\nphysics. Here, we report the observation of glass-like features in the lattice\nheat capacity of a stuffed tridymite-type crystal, Ba1-xSrxAl2O4, a candidate\ncompound of quantum paraelectrics. Substitutional chemical suppression of the\nferroelectric phase transition temperature (TC) of Ba1-xSrxAl2O4 results in the\ndisappearance of the TC at x=0.07. For the compositional window of x=0.2-0.5,\nthe lattice heat capacity is enhanced below approximately 10 K and diverges\nfrom the T3-scaling law below 2.5 K. Synchrotron X-ray diffraction experiments\non single crystals reveal the weakly correlated disorder in the crystal\nstructure that survives down to low temperature; this disorder is responsible\nfor the observed excess heat capacity. These features can be considered one of\nthe manifestations of structural quantum fluctuations.",
        "positive": "First-principles study of structural stability, dynamical and mechanical\n  properties of Li2FeSiO4 polymorphs: Li2FeSiO4 is an important alternative cathode for next generation Li-ion\nbatteries due to its high theoretical capacity (330 mA h/g). However, its\ndevelopment has faced significant challenges arising from structural complexity\nand poor ionic conductivity. In the present work, the relative stability,\nelectronic structure, thermodynamics, and mechanical properties of potential\ncathode material Li2FeSiO4 and its polymorphs have been studied by\nstate-of-the-art density-functional calculations. Among the 11 structural\narrangements considered for the structural optimization calculations, the\nexperimentally known monoclinic P21 modification is found to be the ground\nstate structure. The application of pressure originates a sequence of phase\ntransitions according to P21 - Pmn21 - I222, and the estimated values of the\ncritical pressure are found to be 0.38 and 1.93 GPa. The electronic structures\nreveal that all the considered polymorphs have a non-metallic character, with\nband gap values varying between 3.0 and 3.2 eV. The energy differences between\ndifferent polymorphs are small, and most of these structures are dynamically\nstable. On the other hand, the calculation of single crystal elastic constants\nreveals that only few Li2FeSiO4 polymorphs are mechanically stable. At room\ntemperature, the diffusion coefficient calculations of Li2FeSiO4 in different\npolymorphs reveal that Li-ion conductivity of this material is destitute."
    },
    {
        "anchor": "Intrinsic Spin Decay Length in Antiferromagnetic Insulator: We report intrinsic spin decay length of an antiferromagnetic insulator. We\nfound that at an antiferromagnetic/ferromagnetic interface, a spin current\ngenerated by spin pumping is strongly suppressed by two-magnon scattering. By\neliminating the two-magnon contribution, we discovered that the characteristic\nlength of spin decay in NiO changes by two-orders of magnitude through the\nparamagnetic to antiferromagnetic transition. The spin decay length in the\nantiferromagnetic state is longer than 100 nm, which is an order of magnitude\nlonger than previously believed. These results provide a crucial piece of\ninformation for the fundamental understanding of the physics of spin transport.",
        "positive": "Dynamics of antiferromagnetic skyrmion in absence and presence of\n  pinning defect: A theoretical study on the dynamics of an antiferromagnetic (AFM) skyrmion is\nindispensable for revealing the underlying physics and understanding the\nnumerical and experimental observations. In this work, we present a reliable\ntheoretical treatment of the spin current induced motion of an AFM skyrmion in\nthe absence and presence of pinning defect. For an ideal AFM system free of\ndefect, the skyrmion motion velocity as a function of the intrinsic parameters\ncan be derived, based on the concept that the skyrmion profile agrees well with\nthe 360 domain wall formula, leading to an explicit description of the skyrmion\ndynamics. However, for an AFM lattice containing a defect, the skyrmion can be\npinned and the depinning field as a function of damping constant and pinning\nstrength can be described by the Thiele approach. It is revealed that the\ndepinning behavior can be remarkably influenced by the time dependent\noscillation of the skyrmion trajectory. The present theory provides a\ncomprehensive scenario for manipulating the dynamics of AFM skyrmion,\ninformative for future spintronic applications based on antiferromagnets."
    },
    {
        "anchor": "Efficient Estimation of Band Gaps in Transition-Metal Oxides and\n  Chalcogenides using Density Functional Theory: The performance of two modern density-functionals, HSE06 and TB-mBJ, on\npredicting electronic structures of metal oxides, chalcogenides and nitrides,\nis studied in terms of band gaps, band structure and projected\ndensity-of-states. Contrary to GGA, hybrid functionals and GGA+U, both new\nfunctionals are able to predict band gaps with an appreciable accuracy of 25%\nand thus allow the screening of various classes of (mixed) metal oxides at\nmodest computational cost. The calculated electronic structures are largely\nunaffected by the choice of basis functions and software implementation.",
        "positive": "Density-Dependent Electron Transport and Precise Modeling of GaN HEMTs: We report on the direct measurement of two-dimensional sheet charge density\ndependence of electron transport in AlGaN/GaN high electron mobility\ntransistors. Pulsed IV measurements established increasing electron velocities\nwith decreasing sheet charge densities, resulting in saturation velocity of 1.9\nx 10^7 cm/s at a low sheet charge density of 7.8 x 10^11 cm-2. A new optical\nphonon emission-based electron velocity model for GaN is also presented. It\naccommodates stimulated LO phonon emission which clamps the electron velocity\nwith strong electron-phonon interaction and long LO phonon lifetime in GaN. A\ncomparison with the measured density-dependent saturation velocity shows that\nit captures the dependence rather well. Finally, the experimental result is\napplied in TCAD-based device simulator to predict DC and small signal\ncharacteristics of a reported GaN HEMT. Good agreement between the simulated\nand reported experimental results validated the measurement presented in this\nreport and established accurate modeling of GaN HEMTs."
    },
    {
        "anchor": "Synthesis of FeNi tetrataenite phase by means of chemical precipitation: FeNi L10 (tetrataenite) phase has great perspectives for hard magnetic\nmaterials production. In this paper it was synthesized in chemically\nco-precipitated FeNi nanopowder by means of thermal treating included cycling\nof oxidation and reduction processes at 320 {\\deg}C. The presence of FeNi L10\nphase in the samples was confirmed by magnetic measurements and DSC analysis.",
        "positive": "Anomalous differential conductance of In-Bi2Te3 contact: The differential conductance of In/Bi2Te3 contact under cryogenic temperature\nis investigated. Anomalous zero/finite bias differential conductance has been\nobserved. The dependence of the observed anomalous differential conductance on\nmagnetic field and temperature is studied. Data analysis indicates that the\nanomalous differential conductance is caused by the peculiar transport\nproperties of the superconducting Indium/Bi2Te3 interface where Andreev\nreflection plays a key role."
    },
    {
        "anchor": "Kinetic Monte Carlo Study of Electrochemical Growth in a Heteroepitaxial\n  System: Structural and kinetic aspects of 2-D irreversible metal deposition under\npotentiostatic conditions are analyzed by means of dynamic Monte Carlo\nsimulations employing embedded atom potentials for a model system. Three\nlimiting models, all considering adatom diffusion, were employed to describe\nadatom deposition.The first model (A) considers adatom deposition on any free\nsubstrate site on the surface at the same rate. The second model (B) considers\nadatom deposition only on substrate sites which exhibit no neighboring sites\noccupied by adatoms. The third model (C) allows deposition at higher rates on\nsites presenting neighboring sites occupied by adatoms.",
        "positive": "Stable Half-Metallic Monolayers of FeCl$_2$: The structural, electronic and magnetic properties of single layers of Iron\nDichloride (FeCl$_{2}$) were calculated using first principles calculations. We\nfound that the 1T phase of the single layer FeCl$_{2}$ is 0.17 eV/unit cell\nmore favorable than its 1H phase. The structural stability is confirmed by\nphonon calculations. We found that 1T-FeCl$_{2}$ possess three Raman-active\n(130, 179 and 237 cm$^{-1}$) and one Infrared-active (279 cm$^{-1}$) phonon\nbranches. The electronic band dispersion of the 1T-FeCl$_{2}$ is calculated\nusing both GGA-PBE and DFT-HSE06 functionals. Both functionals reveal that the\n1T-FeCl$_{2}$ has a half-metallic ground state with a Curie temperature of 17\nK."
    },
    {
        "anchor": "Phonon modes and topological phonon properties in (GaN)x/(AlN)x and\n  (AlGaN)x/(GaN)x superlattices: To effectively regulate thermal transport for the near-junction thermal\nmanagement of GaN electronics, it is imperative to gain an understanding of the\nphonon characteristics of GaN nanostructures, particularly the topological\nphonon properties connected to low-dissipation surface phonon states. In this\nwork, a comprehensive study on phonon modes and topological phonon properties\nis performed from first principles in (GaN)x/(AlN)x and (AlGaN)x/(GaN)x\n(x=1,2,3) superlattices. Phonon modes, including the dispersion relation,\ndensity of states, and participation ratio, were calculated for six GaN\nsuperlattices. The participation ratio results did not reveal the localized\nphonon mode. In topological phonon analyses, it is found that Weyl phonons with\na Chern number of 1(-1) are present in all six GaN superlattices, consisting of\ntrivial (GaN) and nontrivial (AlN and AlGaN) combinations. These phonons are\nlocated on either side of the kz = 0 plane symmetrically in the Brillouin zone.\nWith the increase in the number of phonon branches in superlattices, the number\nof Weyl phonon points also increases from dozens to hundreds. One Weyl phonon\nwith significant and clean surface states is selected and analyzed for each GaN\nsuperlattice. Among them, the Weyl phonon in (GaN)2/(AlN)2 superlattice mainly\nresults from the lattice vibrations of Al and Ga atoms, while the Weyl phonons\nin other superlattices mainly result from the lattice vibrations of N atoms.\nThe Weyl phonons at opposite kz planes form pairs in (GaN)2/(AlN)2, AlGaN/GaN,\nand (AlGaN)2/(GaN)2. Effects of strain including biaxial and uniaxial strain on\nWeyl phonons in GaN/AlN and AlGaN/GaN superlattices are investigated. Results\nindicate that Weyl phonons persist in large strain states, however, no\nmonoclinic trend is observed due to the accidental degeneracy of these\nsuperlattices.",
        "positive": "Indirect Exchange Interaction in Fully Metal-Semiconductor Separated\n  SWCNTs Revealed by ESR: The ESR response from highly metal-semiconductor(M-SC) separated SWCNTs for\ntemperatures T between 0.39 and 200 K is characteristically different for the\ntwo systems. The signal originates from defect spins but interaction with free\nelectrons leads to a larger line width for M tubes. The latter decreases with\nincreasing T whereas it increases with T for SC tubes. The spins undergo a\nferromagnetic phase transition below around 10 K. Indirect exchange is\nsuggested to be responsible for the spin-spin interaction, supported by RKKY\ninteraction in the case of M tubes. For SC tubes spin-lattice relaxation via an\nOrbach process is suggested to determine the line width."
    },
    {
        "anchor": "Polymorphism in Bi-based perovskite oxides: a first-principles study: Under normal conditions, bulk crystals of BiScO$_3$ , BiCrO$_3$, BiMnO$_3$,\nBiFeO$_3$, and BiCoO$_3$ present three very different variations of the\nperovskite structure: an antipolar phase, a rhombohedral phase with a large\npolarization along the space diagonal of the pseudocubic unit cell, and a\nsupertetragonal phase with even larger polarization. With the aim of\nunderstanding the causes for this variety, we have used a genetic algorithm to\nsearch for minima in the surface energy of these materials. Our results show\nthat the number of these minima is very large when compared to that of typical\nferroelectric perovskites like BaTiO$_3$ and PbTiO$_3$ , and that a fine energy\nbalance between them results in the large structural differences seen. As\nbyproducts of our search we have identified charge-ordering structures with low\nenergy in BiMnO$_3$ , and several phases with energies that are similar to that\nof the ground state of BiCrO$_3$. We have also found that a inverse\nsupertetragonal phase exists in bulk, likely to be favored in films epitaxially\ngrown at large values of tensile misfit strain.",
        "positive": "Robotic fabrication of high-quality lamellae for aberration-corrected\n  transmission electron microscopy: Aberration-corrected scanning transmission electron microscopy (STEM) is\nwidely used for atomic-level imaging of materials. To accelerate the discovery\nof new materials based on atomic-level investigations, the throughput of\naberration-corrected STEM experiments becomes more and more important. However,\nthe throughput of the full workflow of aberration-corrected STEM is still quite\nlow. A fundamental problem is that the preparation of high-quality thin STEM\nsamples (lamellae) depends on manual operation. Here, inspired by the recent\nsuccesses of \"robot scientists\", we demonstrate robotic fabrication of\nhigh-quality lamellae by focused-ion-beam (FIB) with full automation software.\nFirst, we show that robotic FIB can prepare lamellae with a high success rate,\nwhere the robotic FIB controls rough-milling, lift-out, and final-thinning\nprocesses. Then, we optimize the FIB parameters of the final-thinning process\nfor single crystal Si. Aberration-corrected STEM imaging of these Si lamellae\nshows atomic-level images with 55 pm resolution. We also demonstrate robotic\nfabrication of high-quality lamellae of SrTiO3 and sapphire. The robotic FIB\nsystem will resolve the current bottleneck of the full workflow of\naberration-corrected STEM analysis and accelerate materials discovery based on\natomic-level imaging."
    },
    {
        "anchor": "Quantification of local geometry and local symmetry in models of\n  disordered materials: We suggest two metrics for assessing the quality of atomistic configurations\nof disordered materials, both of which are based on quantifying the\norientational distribution of neighbours around each atom in the configuration.\nThe first metric is that of geometric invariance: i.e., the extent to which the\nneighbour arrangements are as similar as possible for different atoms, allowing\nfor variations in frame of reference. The second metric concerns the degree of\nlocal symmetry. We propose that for a set of configurations with equivalent\npair correlations, ranking highly those configurations with low geometric\ninvariance but with high local symmetry selects for structural simplicity in a\nway that does not rely on formal group theoretical language (and hence\nlong-range periodic order). We show that these metrics rank a range of SiO2 and\na-Si configurations in an intuitive manner, and are also significantly more\nsensitive to unphysical features of those configurations in a way that metrics\nbased on pair correlations are not. We also report that implementation of the\nmetrics within a reverse Monte Carlo algorithm gives rise to an energy\nlandscape that is too coarse (at least in this initial implementation) for\namorphous structure \"solution\".",
        "positive": "Role of tip size, orientation, and structural relaxations in\n  first-principles studies of magnetic exchange force microscopy and\n  spin-polarized scanning tunneling microscopy: Using first-principles calculations based on density functional theory (DFT),\nwe investigate the exchange interaction between a magnetic tip and a magnetic\nsample which is detected in magnetic exchange force microscopy (MExFM) and also\noccurs in spin-polarized scanning tunneling microscopy (SP-STM) experiments. As\na model tip-sample system, we choose Fe tips and one monolayer Fe on W(001)\nwhich exhibits a checkerboard antiferromagnetic structure and has been\npreviously studied with both SP-STM and MExFM. We calculate the exchange forces\nand energies as a function of tip-sample distance using different tip models\nranging from single Fe atoms to Fe pyramids consisting of up to 14 atoms. We\nfind that modelling the tip by a single Fe atom leads to qualitatively\ndifferent tip-sample interactions than using clusters consisting of several\natoms. Increasing the cluster size changes the calculated forces quantitatively\nenhancing the detectable exchange forces. Rotating the tip with respect to the\nsurface unit cell has only a small influence on the tip-sample forces.\nInterestingly, the exchange forces on the tip atoms in the nearest and\nnext-nearest layers from the apex atom are non-negligible and can be opposite\nto that on the apex atom for a small tip. In addition, the apex atom interacts\nnot only with the surface atoms underneath but also with nearest-neighbors in\nthe surface. We find that structural relaxations of tip and sample due to their\ninteraction depend sensitively on the magnetic alignment of the two systems. As\na result the onset of significant exchange forces is shifted towards larger\ntip-sample separations which facilitates their measurement in MExFM. At small\ntip-sample separations, structural relaxations of tip apex and surface atoms\ncan either enhance or reduce the magnetic contrast measured in SP-STM"
    },
    {
        "anchor": "Highly efficient, dual state emission from an organic semiconductor: We report highly efficient, simultaneous fluorescence and phosphorescence\n(74% yield) at room temperature from a single molecule ensemble of (BzP)PB\ndispersed into a polymer host. The slow phosphorescence (208 ms lifetime) is\nvery efficient (50%) at room temperature and only possible because the\nnon-radiative rate for the triplet state is extremely low. The ability of an\norganic molecule to function as an efficient dual state emitter at room\ntemperature is unusual and opens new fields of applications including the use\nas broadband down-conversion emitters, optical sensors and attenuators, exciton\nprobes, and spin-independent intermediates for F\\\"orster resonant energy\ntransfer.",
        "positive": "Enhanced magnetization of ultrathin NiFe$_2$O$_4$ films on\n  SrTiO$_3$(001) related to cation disorder and anomalous strain: NiFe$_2$O$_4$ thin films with varying thickness were grown on SrTiO$_3$(001)\nby reactive molecular beam epitaxy. Soft and hard x-ray photoelectron\nspectroscopy measurements reveal a homogeneous cation distribution throughout\nthe whole film with stoichiometric Ni:Fe ratios of 1:2 independent of the film\nthickness. Low energy electron diffraction and high resolution (grazing\nincidence) x-ray diffraction in addition to x-ray reflectivity experiments were\nconducted to obtain information of the film surface and bulk structure,\nrespectively. For ultrathin films up to 7.3 nm, lateral tensile and vertical\ncompressive strain is observed, contradicting an adaption at the interface of\nNiFe$_2$O$_4$ film and substrate lattice. The applied strain is accompanied by\nan increased lateral defect density, which is decaying for relaxed thicker\nfilms and attributed to the growth of lateral grains. Determination of cationic\nsite occupancies in the inverse spinel structure by analysis of site sensitive\ndiffraction peaks reveals low tetrahedral occupancies for thin, strained\nNiFe$_2$O$_4$ films, resulting in partial presence of deficient rock salt like\nstructures. These structures are assumed to be responsible for the enhanced\nmagnetization of up to $\\sim$250\\% of the NiFe$_2$O$_4$ bulk magnetization as\nobserved by superconducting quantum interference device magnetometry for\nultrathin films below 7.3 nm thickness."
    },
    {
        "anchor": "Metrics for measuring distances in configuration spaces: In order to characterize molecular structures we introduce configurational\nfingerprint vectors which are counterparts of quantities used experimentally to\nidentify structures. The Euclidean distance between the configurational\nfingerprint vectors satisfies the properties of a metric and can therefore\nsafely be used to measure dissimilarities between configurations in the high\ndimensional configuration space. We show that these metrics correlate well with\nthe RMSD between two configurations if this RMSD is obtained from a global\nminimization over all translations, rotations and permutations of atomic\nindices. We introduce a Monte Carlo approach to obtain this global minimum of\nthe RMSD between configurations.",
        "positive": "Phase-field Modeling of Eutectic Solidification: From Oscillations to\n  Invasion: We develop a phase-field model of eutectic growth that uses three phase\nfields, admits strictly binary interfaces as stable solutions, and has a smooth\nfree energy functional. We use this model to simulate oscillatory limit cycles\nin two-dimensional lamellar growth, and find a continuous evolution from\nlow-amplitude oscillations to successive invasions of one solid phase by the\nother when the lamellar spacing is varied."
    },
    {
        "anchor": "Coexistence of glassy antiferromagnetism and giant magnetoresistance\n  (GMR) in Fe/Cr multilayer structures: Using temperature-dependent magnetoresistance and magnetization measurements\non Fe/Cr multilayers that exhibit pronounced giant magnetoresistance (GMR), we\nhave found evidence for the presence of a glassy antiferromagnetic (GAF) phase.\nThis phase reflects the influence of interlayer exchange coupling (IEC) at low\ntemperature (T < 140K) and is characterized by a field-independent glassy\ntransition temperature, Tg, together with irreversible behavior having\nlogarithmic time dependence below a \"de Almeida and Thouless\" (AT) critical\nfield line. At room temperature, where the GMR effect is still robust, IEC\nplays only a minor role, and it is the random potential variations acting on\nthe magnetic domains that are responsible for the antiparallel interlayer\ndomain alignment.",
        "positive": "Ultrafast electron dynamics in Au/Fe/MgO(001) analyzed by Au- and\n  Fe-selective pumping in time-resolved two-photon photoemission spectroscopy:\n  Separation of excitations in adjacent metallic layers: The transport of optically excited, hot electrons in heterostructures is\nanalyzed by femtosecond, time-resolved two-photon photoelectron emission\nspectroscopy (2PPE) for epitaxial Au/Fe/MgO(001). We compare the temporal\nevolution of the 2PPE intensity upon optically pumping Fe or Au, while the\nprobing occurs on the Au surface. In the case of Fe-side pumping, assuming\nindependent relaxation in the Fe and Au layers, we determine the hot electron\nrelaxation times in these individual layers by an analysis of the Au layer\nthickness dependence of the observed, effective electron lifetimes in the\nheterostructure. We show in addition that such a systematic analysis fails for\nthe case of Au-side pumping due to the spatially distributed optical excitation\ndensity, which varies with the Au layer thickness. This work extends a previous\nstudy [Beyazit et al., Phys. Rev. Lett. 125, 076803 (2020)] by new data leading\nto reduced error bars in the determined lifetimes and by a non-linear term in\nthe Au-thickness dependent data analysis which contributes for similar Fe and\nAu film thicknesses."
    },
    {
        "anchor": "Band Structure Mapping of Bilayer Graphene via Quasiparticle Scattering: A perpendicular electric field breaks the layer symmetry of Bernal-stacked\nbilayer graphene, resulting in the opening of a band gap and a modification of\nthe effective mass of the charge carriers. Using scanning tunneling microscopy\nand spectroscopy, we examine standing waves in the local density of states of\nbilayer graphene formed by scattering from a bilayer/trilayer boundary. The\nquasiparticle interference properties are controlled by the bilayer graphene\nband structure, allowing a direct local probe of the evolution of the band\nstructure of bilayer graphene as a function of electric field. We extract the\nSlonczewski-Weiss-McClure model tight binding parameters as $\\gamma_0 = 3.1$\neV, $\\gamma_1 = 0.39$ eV, and $\\gamma_4 = 0.22$ eV.",
        "positive": "Vibrational properties of alpha- and sigma-phase Fe-Cr alloy: Experimental investigation as well as theoretical calculations, of the\nFe-partial phonon density-of-states (DOS) for nominally Fe_52.5Cr_47.5 alloy\nhaving (a) alpha- and (b) sigma-phase structure were carried out. The former at\nsector 3-ID of the Advanced Photon Source, using the method of nuclear resonant\ninelastic X-ray scattering, and the latter with the direct method [K. Parlinski\net al., Phys. Rev. Lett. {78, 4063 (1997)]. The characteristic features of\nphonon DOS, which differentiate one phase from the other, were revealed and\nsuccessfully reproduced by the theory. Various data pertinent to the dynamics\nsuch as Lamb-Mossbauer factor, f, kinetic energy per atom, E_k, and the mean\nforce constant, D, were directly derived from the experiment and the\ntheoretical calculations, while vibrational specific heat at constant volume,\nC_V, and vibrational entropy, S were calculated using the Fe-partial DOS. Using\nthe values of f and C_V, we determined values for Debye temperatures, T_D. An\nexcellent agreement for some quantities derived from experiment and\nfirst-principles theory, like C_V and quite good one for others like D and S\nwas obtained."
    },
    {
        "anchor": "Structure and electronic properties of transition-metal/Mg bimetallic\n  clusters at realistic temperatures and oxygen partial pressures: Composition, atomic structure, and electronic properties of TM$_x$Mg$_y$O$_z$\nclusters (TM = Cr, Ni, Fe, Co, $x+y \\leq 3$) at realistic temperature $T$ and\npartial oxygen pressure $p_{\\textrm{O}_2}$ conditions are explored using the\n{\\em ab initio} atomistic thermodynamics approach. The low-energy isomers of\nthe different clusters are identified using a massively parallel cascade\ngenetic algorithm at the hybrid density-functional level of theory. On\nanalyzing a large set of data, we find that the fundamental gap E$_\\textrm{g}$\nof the thermodynamically stable clusters are strongly affected by the presence\nof Mg-coordinated O$_2$ moieties. In contrast, the nature of the transition\nmetal does not play a significant role in determining E$_\\textrm{g}$. Using\nE$_\\textrm{g}$ of a cluster as a descriptor of its redox properties, our\nfinding is against the conventional belief that the transition metal plays the\nkey role in determining the electronic and therefore chemical properties of the\nclusters. High reactivity may be correlated more strongly with oxygen content\nin the cluster than with any specific TM type.",
        "positive": "Effects of Quantum and Dielectric Confinement on the Emission of\n  Cs-Pb-Br Composites: The halide perovskite CsPbBr$_3$ belongs to the Cs-Pb-Br material system,\nwhich features two additional thermodynamically stable ternary phases,\nCs$_4$PbBr$_6$ and CsPb$_2$Br$_5$. The coexistence of these phases and their\nreportedly similar photoluminescence have resulted in a debate on the nature of\nthe emission in these systems. Here, we combine optical and microscopic\ncharacterization with an effective mass, correlated electron-hole model of\nexcitons in confined systems, to investigate the emission properties of the\nternary phases in the Cs-Pb-Br system. We find that all Cs-Pb-Br phases exhibit\ngreen emission and the non-perovskite phases exhibit photoluminescence quantum\nyields orders of magnitude larger than CsPbBr$_3$. In particular, we measure\nblue- and red-shifted emission for the Cs- and Pb-rich phases, respectively,\nstemming from embedded CsPbBr$_3$ nanocrystals. Our model reveals that the\ndifference in emission shift is caused by the combined effects of nanocrystal\nsize and different band mismatch. Furthermore, we demonstrate the importance of\nincluding the dielectric mismatch in the calculation of the emission energy for\nCs-Pb-Br composites. Our results explain the reportedly limited blue shift in\nCsPbBr$_3$@Cs$_4$PbBr$_6$ composites and rationalize some of its differences\nwith CsPb$_2$Br$_5$."
    },
    {
        "anchor": "Lattice Thermal Conductivity from First Principles and Active Learning\n  with Gaussian Process Regression: The lattice thermal conductivity ($\\kappa_{\\ell}$) is a key materials\nproperty in power electronics, thermal barriers, and thermoelectric devices.\nIdentifying a wide pool of compounds with low $\\kappa_{\\ell}$ is particularly\nimportant in the development of materials with high thermoelectric efficiency.\nThe present study contributed to this with a reliable machine learning (ML)\nmodel based on a training set consisting of 268 cubic compounds. For those,\n$\\kappa_{\\ell}$ was calculated from first principles using the\ntemperature-dependent effective potential (TDEP) method based on forces and\nphonons calculated by density functional theory (DFT). 238 of these were\npreselected and used to train an initial ML model employing Gaussian process\nregression (GPR). The model was then improved with active learning (AL) by\nselecting the 30 compounds with the highest GPR uncertainty as new members of\nan expanded training set. This was used to predict $\\kappa_{\\ell}$ of the 1574\ncubic compounds in the \\textsc{Materials Project} (MP) database with a\nvalidation R2-score of 0.81 and Spearman correlation of 0.93. Out of these, 27\ncompounds were predicted to have very low values of $\\kappa_{\\ell}$ ($\\leq 1.3$\nat 300~K), which was verified by DFT calculations. Some of these have not\npreviously been reported in the literature, suggesting further investigations\nof their electronic thermoelectric properties.",
        "positive": "Magnetic torque anomaly in the quantum limit of the Weyl semi-metal NbAs: Electrons in materials with linear dispersion behave as massless Weyl- or\nDirac-quasiparticles, and continue to intrigue physicists due to their close\nresemblance to elusive ultra-relativistic particles as well as their potential\nfor future electronics. Yet the experimental signatures of Weyl-fermions are\noften subtle and indirect, in particular if they coexist with conventional,\nmassive quasiparticles. Here we report a large anomaly in the magnetic torque\nof the Weyl semi-metal NbAs upon entering the \"quantum limit\" state in high\nmagnetic fields, where topological corrections to the energy spectrum become\ndominant. The quantum limit torque displays a striking change in sign,\nsignaling a reversal of the magnetic anisotropy that can be directly attributed\nto the topological properties of the Weyl semi-metal. Our results establish\nthat anomalous quantum limit torque measurements provide a simple experimental\nmethod to identify Weyl- and Dirac- semi-metals."
    },
    {
        "anchor": "Second-order nonadiabatic couplings from time-dependent density\n  functional theory: Evaluation in the immediate vicinity of\n  Jahn-Teller/Renner-Teller intersections: For a rigorous quantum simulation of nonadiabatic dynamics of electrons and\nnuclei, knowledge of not only first-order but also second-order nonadiabatic\ncouplings (NAC), is required. Here we propose a method to efficiently calculate\nsecond-order NAC from time-dependent density functional theory (TDDFT), on the\nbasis of the Casida ansatz adapted for the computation of first-order NAC,\nwhich has been justified in our previous work and can be shown to be valid for\ncalculating second-order NAC between ground state and singly excited states\nwithin the Tamm-Dancoff approximation. Test calculations of second-order NAC in\nthe immediate vicinity of Jahn-Teller and Renner-Teller intersections show that\ncalculation results from TDDFT, combined with modified linear response theory,\nagree well with the prediction from the Jahn-Teller / Renner-Teller models.\nContrary to the diverging behavior of first-order NAC near all types of\nintersection points, the Cartesian components of second-order NAC are shown to\nbe negligibly small near Renner-Teller glancing intersections, while they are\nsignificantly large near the Jahn-Teller conical intersections. Nevertheless,\nthe components of second-order NAC can cancel each other to a large extent in\nJahn-Teller systems, indicating the background of neglecting second-order NAC\nin practical dynamics simulations. On the other hand, it is shown that such a\ncancellation becomes less effective in an elliptic Jahn-Teller system and thus\nthe role of second-order NAC needs to be evaluated in the rigorous framework.\nOur study shows that TDDFT is promising to provide accurate data of NAC for\nfull quantum mechanical simulation of nonadiabatic processes.",
        "positive": "Probing correlations in the exciton landscape of a moir\u00e9\n  heterostructure: Excitons are two-particle correlated bound states that are formed due to\nCoulomb interaction between single-particle holes and electrons. In the\nsolid-state, cooperative interactions with surrounding quasiparticles can\nstrongly tailor the exciton properties and potentially even create new\ncorrelated states of matter. It is thus highly desirable to access such\ncooperative and correlated exciton behavior on a fundamental level. Here, we\nfind that the ultrafast transfer of an exciton's hole across a type-II\nband-aligned moir\\'e heterostructure leads to a surprising sub-200-fs upshift\nof the single-particle energy of the electron being photoemitted from the\ntwo-particle exciton state. While energy relaxation usually leads to an\nenergetic downshift of the spectroscopic signature, we show that this unusual\nupshift is a clear fingerprint of the correlated interactions of the electron\nand hole parts of the exciton quasiparticle. In this way, time-resolved\nphotoelectron spectroscopy is straightforwardly established as a powerful\nmethod to access exciton correlations and cooperative behavior in\ntwo-dimensional quantum materials. Our work highlights this new capability and\nmotivates the future study of optically inaccessible correlated excitonic and\nelectronic states in moir\\'e heterostructures."
    },
    {
        "anchor": "A critical assessment on Kassapoglou's statistical model for composites\n  fatigue: Kassapoglou recently proposed a model for fatigue of composite materials\nwhich seems to suggest that fatigue SN curve can be entirely predicted on the\nbasis of the statistical distribution of static strengths. The original\nabstract writes \"Expressions for the cycles to failure as a function of R ratio\nare derived. These expressions do not require any curve fitting and do not\ninvolve any experimentally determined parameters. The fatigue predictions do\nnot require any fatigue tests for calibration\". These surprisingly ambitious\nclaims and attractive results deserve careful scrutiny. We contend that the\nresults seem to be due to a number of approximations and incorrect derivations,\nand one particular misleading assumption, which make the model not conform to a\nfatigue testing in a given specimen with resulting SN curve distribution. The\nquantitative agreement of some predictions (the scatter of distribution of\nfatigue lives being close to the mode value found in typical composites of\naeronautical interest in the large Navy database) should not motivate any\nenthusiasm. It is believed that a proper statistical treatment of the fatigue\nprocess should not make wear-out constants disappear, and hence the SN curves\nwould depend on them, and not just on scatter of static data. These serious\nconcerns explain the large discrepancies found by 3 independent studies which\ntried to apply Kassapoglou's model to composite fatigue data, and to other well\nknown results.",
        "positive": "Efficient all-optical helicity dependent switching of spins in a\n  Pt/Co/Pt film by a dual-pulse excitation: All-optical helicity dependent switching (AO-HDS), deterministic control of\nmagnetization by circularly polarized laser pulses, allows to efficiently\nmanipulate spins without the need of a magnetic field. However, AO-HDS in\nferromagnetic metals so far requires many laser pulses for fully switching\ntheir magnetic states. Using a combination of a short, 90-fs linearly polarized\npulse and a subsequent longer, 3-ps circularly polarized pulse, we demonstrate\nthat the number of pulses for full magnetization reversal can be reduced to 4\npulse pairs in a single stack of Pt/Co/Pt. The obtained results suggest that\nthe dual-pulse approach is a potential route towards realizing efficient AO-HDS\nin ferromagnetic metals."
    },
    {
        "anchor": "Failure mechanisms of graphene under tension: Recent experiments established pure graphene as the strongest material known\nto mankind, further invigorating the question of how graphene fails. Using\ndensity functional theory, we reveal the mechanisms of mechanical failure of\npure graphene under a generic state of tension. One failure mechanism is a\nnovel soft-mode phonon instability of the $K_1$-mode, whereby the graphene\nsheet undergoes a phase transition and is driven towards isolated benzene rings\nresulting in a reduction of strength. The other is the usual elastic\ninstability corresponding to a maximum in the stress-strain curve. Our results\nindicate that finite wave vector soft modes can be the key factor in limiting\nthe strength of monolayer materials.",
        "positive": "Influence of irradiation on defect spin coherence in silicon carbide: Irradiation-induced lattice defects in silicon carbide (SiC) have already\nexceeded their previous reputation as purely performance-inhibiting. With their\nremarkable quantum properties, such as long room-temperature spin coherence and\nthe possibility of downscaling to single-photon source level, they have proven\nto be promising candidates for a multitude of quantum information applications.\nOne of the most crucial parameters of any quantum system is how long its\nquantum coherence can be preserved. By using the pulsed optically detected\nmagnetic resonance (ODMR) technique, we investigate the spin-lattice relaxation\ntime ($T_1$) and spin coherence time ($T_2$) of silicon vacancies in 4H-SiC\ncreated by neutron, electron and proton irradiation in a broad range of\nfluences. We also examine the effect of irradiation energy and sample\nannealing. We establish a robustness of the $T_1$ time against all types of\nirradiation and reveal a universal scaling of the $T_2$ time with the emitter\ndensity. Our results can be used to optimize the coherence properties of\nsilicon vacancy qubits in SiC for specific tasks."
    },
    {
        "anchor": "A Single Mobility Function for the Square-Lattice Ising Model and Its\n  Application to Calibrated Monte Carlo Kinetics: Computational experiments are used to show that grain boundary mobility is\nindependent of driving force in a two-dimensional, square-lattice Ising model\nwith Metropolis kinetics. This is established over the entire Monte Carlo\ntemperature range. A calibration methodology is then introduced which endows\nthe Monte Carlo algorithm with time and length scales and allows the Monte\nCarlo parameters to be expressed directly in terms of experimentally measurable\nparameters. A comparison of results obtained for a variety of driving forces\nand temperature conditions indicates that such Calibrated Monte Carlo models\nare able to capture the grain boundary kinetics predicted by sharp-interface\ntheory.",
        "positive": "Topological nodal-line fermions in ZrSiSe and ZrSiTe: The discovery of topological semimetal phase in three-dimensional (3D)\nsystems is a new breakthrough in topological material research. Dirac\nnodal-line semimetal is one of the three topological semimetal phases\ndiscovered so far; it is characterized by linear band crossing along a\nline/loop, contrasted with the linear band crossing at discrete momentum points\nin 3D Dirac and Weyl semimetals. The study of nodal-line semimetal is still at\ninitial stage; only three material systems have been verified to host nodal\nline fermions until now, including PbTaSe2, PtSn 4and ZrSiS. In this letter, we\nreport evidence of nodal line fermions in ZrSiSe and ZrSiTe probed in de Haas -\nvan Alphen (dHvA) quantum oscillations. Although ZrSiSe and ZrSiTe share\nsimilar layered structure with ZrSiS, our measurements of angular dependences\nof dHvA oscillations indicate the Fermi surface (FS) enclosing Dirac nodal line\nis of 2D character in ZiSiTe, in contrast with 3D-like FS in ZrSiSe and ZrSiS.\nAnother important property revealed in our experiment is that the nodal line\nfermion density in ZrSi(S/Se) (~ 10^20-10^21 cm^-3) is much higher than the\nDirac/Weyl fermion density of any known topological materials. In addition, we\nhave demonstrated ZrSiSe and ZrSiTe single crystals can be thinned down to 2D\natomic thin layers through microexfoliation, which offers a promising platform\nto verify the predicted 2D topological insulator in the monolayer materials\nwith ZrSiS-type structure"
    },
    {
        "anchor": "Excitons in carbon nanotubes: an ab initio symmetry-based approach: The optical absorption spectrum of the carbon (4,2) nanotube is computed\nusing an ab-initio many-body approach which takes into account excitonic\neffects. We develop a new method involving a local basis set which is symmetric\nwith respect to the screw symmetry of the tube. Such a method has the\nadvantages of scaling faster than plane-wave methods and allowing for a precise\ndetermination of the symmetry character of the single particle states,\ntwo-particle excitations, and selection rules. The binding energy of the\nlowest, optically active states is approximately 0.8 eV. The corresponding\nexciton wavefunctions are delocalized along the circumference of the tube and\nlocalized in the direction of the tube axis.",
        "positive": "Temperature induced transition from p-n to n-n electronic behavior in\n  Ni0.07Zn0.93O/Mg0.21Zn0.79O heterojunction: The transport characteristics across the pulsed laser deposited\nNi0.07Zn0.93O/Mg0.21Zn0.79O heterojunction exhibits p-n type semiconducting\nproperties at 10 K while at 100 K, its characteristics become similar to that\nof an n-n junction. The reason for the same is attributed to the role of larger\nelectronegativity of Ni as compared to Mg at 10 K and ionization of impurity\nstates at 100 K. The above behavior is confirmed by performing the Hall\nmeasurements."
    },
    {
        "anchor": "Heisenberg Exchange and Dzyaloshinskii-Moriya Interaction in Ultrathin\n  CoFeB Single and Multilayers: We present results of the analysis of Brillouin Light Scattering (BLS)\nmeasurements of spin waves performed on ultrathin single and multirepeat CoFeB\nlayers with adjacent heavy metal layers. From a detailed study of the spin-wave\ndispersion relation, we independently extract the Heisenberg exchange\ninteraction (also referred to as symmetric exchange interaction), the\nDzyaloshinskii-Moriya interaction (DMI, also referred to as antisymmetric\nexchange interaction), and the anisotropy field. We find a large DMI in CoFeB\nthin films adjacent to a Pt layer and nearly vanishing DMI for CoFeB films\nadjacent to a W layer. Furthermore, the residual influence of the dipolar\ninteraction on the dispersion relation and on the evaluation of the Heisenberg\nexchange parameter is demonstrated. In addition, an experimental analysis of\nthe DMI on the spin-wave lifetime is presented. All these parameters play a\ncrucial role in designing skyrmionic or spin-orbitronic devices.",
        "positive": "Spin-orbit splitting of image states: We quantify the effect of the spin-orbit interaction on the Rydberg-like\nseries of image state electrons at the (111) and (001) surface of Ir, Pt and\nAu. Using relativistic multiple-scattering methods we find Rashba-like\ndispersions with Delta E(K)=gamma K with values of gamma for n=1 states in the\nrange 38-88 meV Angstrom. Extending the phase-accumulation model to include\nspin-orbit scattering we find that the splittings vary like 1/(n+a)^3 where a\nis the quantum defect and that they are related to the probability of spin-flip\nscattering at the surface. The splittings should be observable experimentally\nbeing larger in magnitude than some exchange-splittings that have been resolved\nby inverse photoemission, and are comparable to linewidths from inelastic\nlifetimes."
    },
    {
        "anchor": "Real-time ab initio description of the photon-echo mechanisms in\n  extended systems: the case study of bulk GaAs: In this paper we present an ab initio real-time analysis of free polarization\ndecay and photon echo in extended systems. As a prototype material, we study\nbulk GaAs driven by ultra-short laser pulses of 10 fs (energy spread of 0.4\neV), with frequency tuned in the continuum of the optical spectrum. We compute\nthe electronic polarization P(t), and define a computational procedure to\nextract the echo signal in the dipole approximation. Results are obtained in\nboth the low and high field regime, and compared with a two-levels system (TLS)\nmodel, with parameters extracted from the ab initio simulations. ab initio\nresults are in optimal agreement with the TLS in the low-field case, whereas\nsome differences are observed in the high-field regime where the multi-band\nnature of GaAs becomes relevant. In the high field regime we compute the pulse\narea, and look for fluences with pulse area close to {\\pi}. We highlight that\nsuch fluences are well below the damage threshold of GaAs. However a unique\nvalue of the area cannot be defined, due to the strong dependence of the\ntransition dipoles in the energy window excited by the laser pulse.",
        "positive": "The Interplay Between Solute Atoms and Vacancy Clusters in Magnesium\n  Alloys: Atomic-scale calculations indicate that both stress effects and chemical\nbinding contribute to the redistribution of solute in the presence of vacancy\nclusters in magnesium alloys. As the size of the vacancy cluster increases,\nchemical binding becomes more important relative to stress. By affecting the\ndiffusivity of vacancies and vacancy clusters, solute atoms facilitate\nclustering and stabilize the resulting vacancy clusters, increasing their\npotential to promote solute segregation and to serve as heterogeneous\nnucleation sites during precipitation. Experimental observation of solute\nsegregation in simultaneously deformed and aged Mg-Al alloys provides support\nfor this mechanism."
    },
    {
        "anchor": "Lie groups in nonequilibrium thermodynamics: Geometric structure behind\n  viscoplasticity: Poisson brackets provide the mathematical structure required to identify the\nreversible contribution to dynamic phenomena in nonequilibrium thermodynamics.\nThis mathematical structure is deeply linked to Lie groups and their Lie\nalgebras. From the characterization of all the Lie groups associated with a\ngiven Lie algebra as quotients of a universal covering group, we obtain a\nnatural classification of rheological models based on the concept of discrete\nreference states and, in particular, we find a clear-cut and deep distinction\nbetween viscoplasticity and viscoelasticity. The abstract ideas are illustrated\nby a naive toy model of crystal viscoplasticity, but similar kinetic models are\nalso used for modeling the viscoplastic behavior of glasses. We discuss some\nimplications for coarse graining and statistical mechanics.",
        "positive": "Experimental Observation of Kondo-Fano Resonant Tunneling in\n  Silicon-Doped GaAs/AlAs Multiple Quantum Wells: We report experimental observation of Kondo-Fano resonant tunneling in\nSi-doped GaAs/AlAs multiple quantum wells. The spectrum of differential\ntunneling conductance at low bias shows a strong temperature dependent\nresonance, whose peak is split in the presence of a magnetic field,\ncharacteristic of a Kondo resonance. The data is well explained as a resonant\ntunneling of conduction electrons at the Fermi level through the doped silicon\nimpurity states inside the wells by using an impurity Anderson model. The\nCoulomb blockade resonance of the impurity states induces a Fano dip above the\nKondo resonance."
    },
    {
        "anchor": "In-Liquido Computation with Electrochemical Transistors and Mixed\n  Conductors for Intelligent Bioelectronics: Next-generation implantable computational devices require long-term stable\nelectronic components capable of operating in, and interacting with,\nelectrolytic surroundings without being damaged. Organic electrochemical\ntransistors (OECTs) emerged as fitting candidates. However, while single\ndevices feature impressive figures of merit, integrated circuits (ICs) immersed\nin a common electrolytes are hard to realize using electrochemical transistors,\nand there is no clear path forward for optimal top-down circuit design and\nhigh-density integration. The simple observation that two OECTs immersed in the\nsame electrolytic medium will inevitably interact hampers their implementation\nin complex circuitry. The electrolyte's ionic conductivity connects all the\ndevices in the liquid, producing unwanted and often unforeseeable dynamics.\nMinimizing or harnessing this crosstalk has been the focus of very recent\nstudies.\n  In this Perspective, we discuss the main challenges, trends, and\nopportunities for realizing OECT-based circuitry in a liquid environment that\ncould circumnavigate the hard limits of engineering and human physiology. We\nanalyze the most successful approaches in autonomous bioelectronics and\ninformation processing. Elaborating on the strategies to circumvent and harness\ndevice crosstalk proves that platforms capable of complex computation and even\nmachine learning can be realized in-liquido using mixed ionic-electronic\nconductors.",
        "positive": "Water-Induced Bimetallic Alloy Surface Segregation: A First Principle\n  Study: Bimetallic alloys have drawn extensive attentions in materials science due to\ntheir widespread applications in electronics, engineering and catalysis. A very\nfundamental question of alloy is its surface segregation phenomenon. Many\nrecent observations have shown that reactive gases or supports may have strong\neffects on alloy segregation. However, segregation in water, the most common\nsolvent and environment, has not received enough attention. In this paper we\ngive the quantitative descriptions on the surface segregation energies of 23\ntransition-metal impurities in Cu hosts under the conditions of water\nadsorption by performing density functional theory (DFT) calculations. The\ngeneral trends in the changes of segregation energies caused by water\nadsorption are established. Our results show water adsorption could induce\nstrong surface segregation tendencies for early and middle transition metals in\nCu alloys. This finding not only prompts us to re-examine the potential effects\nof water on bimetallic alloy surfaces, but would be also very helpful as a\nguide for the further theoretical and experimental studies in this field."
    },
    {
        "anchor": "Second-harmonic generation and linear electro-optical coefficients of\n  SiC polytypes and nanotubes: The second-order nonlinear optical susceptibility ($\\chi_{abc}^{(2)}$) and\nlinear electro-optical coefficient ($r_{abc}$) of a large number of\nsingle-walled zigzag, armchair and chiral SiC nanotubes (SiC-NTs) as well as\nbulk SiC polytypes (2H-, 4H-, 6H- and 3C-SiC) and single graphitic SiC sheet\nhave been calculated from first-principles. The calculations are based on\ndensity functional theory in the local density approximation and highly\naccurate full-potential projector augmented-wave method is used. Both the\nzigzag and chiral SiC-NTs are found to exhibit large second-order nonlinear\noptical behavior with the $\\chi_{abc}^{(2)}$ and $r_{abc}$ coefficients being\nup to ten-times larger than that of bulk SiC polytypes, and also being up to\nthirteen-times larger than the counterparts of the corresponding BN-NTs,\nindicating that SiC-NTs are promising materials for nonlinear optical and\nopto-electric applications. The prominant features in the spectra of\n$\\chi_{abc}^{(2)}(-2\\omega,\\omega,\\omega)$ of the SiC-NTs are correlated with\nthe features in the linear optical dielectric function $\\epsilon (\\omega)$ in\nterms of single-photon and two-photon resonances.",
        "positive": "Theory of spin loss at metallic interfaces: Interfacial spin-flip scattering plays an important role in magnetoelectronic\ndevices. Spin loss at metallic interfaces is usually quantified by matching the\nmagnetoresistance data for multilayers to the Valet-Fert model, while treating\neach interface as a fictitious bulk layer whose thickness is $\\delta$ times the\nspin-diffusion length. By employing the properly generalized circuit theory and\nthe scattering matrix approaches, we derive the relation of the parameter\n$\\delta$ to the spin-flip transmission and reflection probabilities at an\nindividual interface. It is found that $\\delta$ is proportional to the square\nroot of the probability of spin-flip scattering. We calculate the spin-flip\ntransmission probability for flat and rough Cu/Pd interfaces using the\nLandauer-B\\\"uttiker method based on the first-principles electronic structure\nand find $\\delta$ in reasonable agreement with experiment."
    },
    {
        "anchor": "Machine learning accelerated discovery of corrosion-resistant\n  high-entropy alloys: Corrosion has a wide impact on society, causing catastrophic damage to\nstructurally engineered components. An emerging class of corrosion-resistant\nmaterials are high-entropy alloys. However, high-entropy alloys live in\nhigh-dimensional composition and configuration space, making materials designs\nvia experimental trial-and-error or brute-force ab initio calculations almost\nimpossible. Here we develop a physics-informed machine-learning framework to\nidentify corrosion-resistant high-entropy alloys. Three metrics are used to\nevaluate the corrosion resistance, including single-phase formability, surface\nenergy and Pilling-Bedworth ratios. We used random forest models to predict the\nsingle-phase formability, trained on an experimental dataset. Machine learning\ninter-atomic potentials were employed to calculate surface energies and\nPilling-Bedworth ratios, which are trained on first-principles data fast\nsampled using embedded atom models. A combination of random forest models and\nhigh-fidelity machine learning potentials represents the first of its kind to\nrelate chemical compositions to corrosion resistance of high-entropy alloys,\npaving the way for automatic design of materials with superior corrosion\nprotection. This framework was demonstrated on AlCrFeCoNi high-entropy alloys\nand we identified composition regions with high corrosion resistance. Machine\nlearning predicted lattice constants and surface energies are consistent with\nvalues by first-principles calculations. The predicted single-phase formability\nand corrosion-resistant compositions of AlCrFeCoNi agree well with experiments.\nThis framework is general in its application and applicable to other materials,\nenabling high-throughput screening of material candidates and potentially\nreducing the turnaround time for integrated computational materials\nengineering.",
        "positive": "Quantifying Dynamic Tilting in Halide Perovskites: Chemical Trends and\n  Local Correlations: Halide perovskites have emerged as one of the most interesting materials for\noptoelectronic applications due to their favorable properties, such as\ndefect-tolerance and long charge carrier lifetimes, which are attributed to\ntheir dynamic softness. However, this softness has led to apparent\ndisagreements between the local instantaneous and global average structures of\nthese materials. In this work, we assess the local tilt angles of octahedra in\nthe perovskite structure through large-scale molecular dynamics simulations\nusing machine learned potentials based on density functional theory. We compare\nstructural properties given by different density functionals, namely PBE,\nPBEsol, SCAN, and vdW-DF-cx, and establish trends across a family of CsMX3 with\nM=Sn or Pb and X=Cl, Br or I perovskites. Notably, we demonstrate a strong\nshort-range ordering that persists even in the cubic phase of halide\nperovskites. This ordering is reminiscent of the tetragonal phase and bridges\nthe disordered local structure and the global cubic arrangement. Our results\nprovide a deeper understanding of the structural properties of halide\nperovskites and their local distortions, which is crucial for further\nunderstanding their optoelectronic properties."
    },
    {
        "anchor": "Analysis of dynamic failure of the discrete chain structure with\n  non-local interactions: In the present work the steady-state crack propagation in a chain of\noscillators with non-local interactions is considered. The interactions are\nmodeled as linear springs while the crack is presented by the absence of extra\nsprings. The problem is reduced to the Wiener-Hopf type and solution is\npresented in terms of inverse Fourier transform. It is shown that the non-local\ninteractions may change the structure of the problem solution well-known from\nthe classical local interactions formulation. In particular, it may change the\nrange of the region of stable crack motion. The conclusions of the analysis are\nsupported by numerical results. Namely, the observed phenomenon is partially\nclarified by evaluation of the structure profiles on the crack line ahead.",
        "positive": "Anisotropy of exchange stiffness based on atomic-scale magnetic\n  properties in rare-earth permanent magnet Nd$_2$Fe$_{14}$B: We examine the anisotropic properties of the exchange stiffness constant,\n$\\mathcal{A}$, for rare-earth permanent magnet, Nd$_2$Fe$_{14}$B, by connecting\nanalyses with two different scales of length, i.e., Monte Carlo (MC) method\nwith an atomistic spin model and Landau-Lifshitz-Gilbert (LLG) equation with a\ncontinuous magnetic model. The atomistic MC simulations are performed on the\nspin model of Nd$_2$Fe$_{14}$B constructed from ab-initio calculations, and the\nLLG micromagnetics simulations are performed with the parameters obtained by\nthe MC simulations. We clarify that the amplitude and the thermal property of\n$\\mathcal{A}$ depend on the orientation in the crystal, which are attributed to\nthe layered structure of Nd atoms and weak exchange couplings between Nd and Fe\natoms. We also confirm that the anisotropy of $\\mathcal{A}$ significantly\naffects the threshold field for the magnetization reversal (coercivity) given\nby the depinning process."
    },
    {
        "anchor": "Flow Visualization of The Buoyancy-induced Convective Heat Transfer in\n  Electronics Cooling: The aim of this work is to develop a simple optical method for the\nvisualization of the natural convection flow generated in an electronic system\nduring its normal operation. The presented experimental set-up allows to reveal\nlocal refractive index changes in a phase objects. A fringe pattern is\nacquired, through the cooling fluid under analysis, with a digital camera two\ntimes: the first one with the fluid at rest, the second one with the thermal\nload due to the electronic device normal operation. By the means of the MATLAB\nprocessing of the acquired images it&#8217;s possible to reveal the shape and\nthe directions of the thermal flow lines for the cooling fluid. In this way we\ncan obtain a deeper understanding of the optimal convection working volume or\ninformation for the optimization of the relative spatial positioning of the\nseveral electronic components in a complex electronic system, like a printed\ncircuit board (PCB). The proposed technique has been tested on two typical heat\nextraction situations recurrent in the electronic devices. In this paper are\npresented the experimental results of the visualization of the convective flow,\nin air, for an heat sink and a power resistor.",
        "positive": "Tuning the polarization-induced free hole density in nanowires graded\n  from GaN to AlN: We report a systematic study of p-type polarization induced doping in graded\nAlGaN nanowire light emitting diodes grown on silicon wafers by plasma-assisted\nmolecular beam epitaxy. The composition gradient in the p-type base is varied\nin a set of samples from 0.7 %Al/nm to 4.95 %Al/nm corresponding to negative\nbound polarization charge densities of 2.2x10^18 cm^-3 to 1.6x10^19 cm^-3.\nCapacitance measurements and energy band modeling reveal that for gradients\ngreater than or equal to 1.30 %Al/nm, the deep donor concentration is\nnegligible and free hole concentrations roughly equal to the bound polarization\ncharge density are achieved up to 1.6x10^19 cm^-3 at a gradient of 4.95 %Al/nm.\nAccurate grading lengths in the p- and n-side of the pn-junction are extracted\nfrom scanning transmission electron microscopy images and are used to support\nenergy band calculation and capacitance modeling. These results demonstrate the\nrobust nature of p-type polarization doping in nanowires and put an upper bound\non the magnitude of deep donor compensation."
    },
    {
        "anchor": "Electronic Structure and Thermoelectric Properties of Half-Heusler\n  Alloys NiTZ: We have investigated the electronic and thermoelectric properties of\nhalf-Heusler alloys NiTZ (T = Sc, and Ti; Z = P, As, Sn, and Sb) having 18\nvalence electron. Calculations are performed by means of density functional\ntheory and Boltzmann transport equation with constant relaxation time\napproximation, validated by NiTiSn. The chosen half-Heuslers are found to be an\nindirect band gap semiconductor, and the lattice thermal conductivity is\ncomparable with the state-of-the-art thermoelectric materials. The estimated\npower factor for NiScP, NiScAs, and NiScSb reveals that their thermoelectric\nperformance can be enhanced by appropriate doping rate. The value of ZT found\nfor NiScP, NiScAs, and NiScSb are 0.46, 0.35, and 0.29, respectively at 1200 K.",
        "positive": "A Decade of Piezoresponse Force Microscopy: Progress, Challenges and\n  Opportunities: Coupling between electrical and mechanical phenomena is a near-universal\ncharacteristic of inorganic and biological systems alike, with examples ranging\nfrom ferroelectric perovskites to electromotor proteins in cellular membranes.\nUnderstanding electromechanical functionality in materials such as\nferroelectric nanocrystals, thin films, relaxor ferroelectrics, and biosystems\nrequires probing these properties on the nanometer level of individual grain,\ndomain, or protein fibril. In the last decade, Piezoresponse Force Microscopy\n(PFM) was established a powerful tool for nanoscale imaging, spectroscopy, and\nmanipulation of ferroelectric and piezoelectric materials. Here, we present\nprinciples and recent advances in PFM, including vector and frequency dependent\nimaging of piezoelectric materials, briefly review applications for\nferroelectric materials, discuss prospects for electromechanical imaging of\nlocal crystallographic and molecular orientations and disorder, and summarize\nfuture challenges and opportunities for PFM emerging in the second decade since\nits invention."
    },
    {
        "anchor": "Layer Dependence of Stacking Order in Nonencapsulated Few-layer CrI3: Long-range magnetic orders in atomically thin ferromagnetic CrI3 give rise to\nnew fascinating physics and application perspectives. The physical properties\nof two-dimensional (2D) ferromagnetism CrI3 are significantly influenced by\ninterlayer spacing and stacking order, which are sensitive to the hydrostatic\npressure and external environments. However, there remains debate on the\nstacking order at low temperature. Here, we study the interlayer coupling and\nstacking order of non-encapsulated 2-5 layer and bulk CrI3 at 10 K by Raman\nspectroscopy; demonstrate a rhombohedral stacking in both antiferromagnetic and\nferromagnetic CrI3. The opposite helicity dependence of Ag and Eg modes arising\nfrom phonon symmetry further validate the rhombohedral stacking. An anomalous\ntemperature-dependent behavior is observed due to spin-phonon coupling below 60\nK. Our work provides insights into the interlayer coupling and stacking orders\nof 2D ferromagnetic materials.",
        "positive": "Electrical detection of the spin reorientation transition in\n  antiferromagnetic TmFeO$_3$ thin films by spin Hall magnetoresistance: TmFeO$_3$ (TFO) is a canted antiferromagnet that undergoes a spin\nreorientation transition (SRT) with temperature between 82 K and 94 K in single\ncrystals. In this temperature region, the N\\'eel vector continuously rotates\nfrom the crystallographic $c$-axis (below 82 K) to the $a$-axis (above 94 K).\nThe SRT allows for a temperature control of distinct antiferromagnetic states\nwithout the need for a magnetic field, making it apt for applications working\nat THz frequencies. For device applications, thin films of TFO are required as\nwell as an electrical technique for reading out the magnetic state. Here we\ndemonstrate that orthorhombic TFO thin films can be grown by pulsed laser\ndeposition and the detection of the SRT in TFO thin films can be accessed by\nmaking use of the all electrical spin Hall magnetoresistance (SMR), in good\nagreement for the temperature range where the SRT occurs. Our results\ndemonstrate that one can electrically detect the SRT in insulators."
    },
    {
        "anchor": "Emission of Linearly Polarized Single Photons from Quantum Dots\n  Contained in Nonpolar, Semipolar, and Polar Sections of Pencil-Like InGaN/GaN\n  Nanowires: A pencil-like morphology of homoepitaxially grown GaN nanowires is exploited\nfor the fabrication of thin conformal intrawire InGaN nanoshells which host\nquantum dots in nonpolar, semipolar and polar crystal regions. All three\nquantum dot types exhibit single photon emission with narrow emission line\nwidths and high degrees of linear optical polarization. The host crystal region\nstrongly affects both single photon wavelength and emission lifetime, reaching\nsubnanosecond time scales for the non- and semipolar quantum dots. Localization\nsites in the InGaN potential landscape, most likely induced by indium\nfluctuations across the InGaN nanoshell, are identified as the driving\nmechanism for the single photon emission. The hereby reported pencil-like InGaN\nnanoshell is the first single nanostructure able to host all three types of\nsingle photon sources and is, thus, a promising building block for tunable\nquantum light devices integrated into future photonic circuits.",
        "positive": "The Effects of Geometry on a-Si:H Solar Cell Performance: We present a model for simulating performance of 3D nano -coaxial and\n-hemispherical thin film solar cells. The material system considered in these\nsimulations is hydrogenated amorphous silicon (a-Si:H), with solar cells\nfabricated in an n-i-p stacking architecture. Simulations for the performance\nof the planar a-Si:H device are compared against simulations performed using\nSCAPS-1D and found to be in close agreement. Electrical and optical properties\nof devices are discussed for the respective geometries. Maximum power point\nefficiencies are plotted as a function of i-layer thickness for insight into\noptimizing spatial parameters. Simulation results show that while geometrical\nchanges in the energy band diagram impact charge carrier collection, a-Si:H\nsolar cell performance is most significantly impacted by light absorption\nproperties associated with nanoscopic arrays of non-planar structures. We\ncompare our simulations to results of fabricated nanocoaxial a-Si:H solar cells\nand infer the mechanisms of enhanced absorption observed experimentally in such\nsolar cells."
    },
    {
        "anchor": "Perspective: Heusler interfaces -- opportunities beyond spintronics?: Heusler compounds, in both cubic and hexagonal polymorphs, exhibit a\nremarkable range of electronic, magnetic, elastic, and topological properties,\nrivaling that of the transition metal oxides. To date, research on these\nquantum materials has focused primarily on bulk magnetic and thermoelectric\nproperties or on applications in spintronics. More broadly, however, Heuslers\nprovide a platform for discovery and manipulation of emergent properties at\nwell-defined crystalline interfaces. Here, motivated by advances in the\nepitaxial growth of layered Heusler heterostructures, I present a vision for\nHeusler interfaces, focusing on the frontiers and challenges that lie beyond\nspintronics. The ability to grow these materials epitaxially on technologically\nimportant semiconductor substrates, such as GaAs, Ge, and Si, provides a direct\npath for their integration with modern electronics. Further advances will\nrequire new methods to control the stoichiometry and defects to \"electronic\ngrade\" quality, and to control the interface abruptness and ordering at the\natomic scale.",
        "positive": "Minimum energy paths for dislocation nucleation in strained epitaxial\n  layers: We study numerically the minimum energy path and energy barriers for\ndislocation nucleation in a two-dimensional atomistic model of strained\nepitaxial layers on a substrate with lattice misfit. Stress relaxation\nprocesses from coherent to incoherent states for different transition paths are\ndetermined using saddle point search based on a combination of repulsive\npotential minimization and the Nudged Elastic Band method. The minimum energy\nbarrier leading to a final state with a single misfit dislocation nucleation is\ndetermined. A strong tensile-compressive asymmetry is observed. This asymmetry\ncan be understood in terms of the qualitatively different transition paths for\nthe tensile and compressive strains."
    },
    {
        "anchor": "Apertureless Near-Field Second Harmonic Microscopy with Bare Tapered\n  Optical Fiber Tips: We present a near-field optical technique for second harmonic imaging using\nbare tapered optical fiber tip illuminated with femtosecond laser pulses.\nEnhancement of electric field at the tip of the fiber results in enhanced\nsecond harmonic generation (SHG) from the sample region near the tip. This SH\nemission is collected by the same tapered fiber. Spatial distribution of SHG\nfrom thin ferroelectric Pb(Zr_xTi_1-x)O_3 films and model metal-ferroelectric\ndevices has been studied. Spatial resolution on the order of 80 nm has been\nachieved. This is the first time diffraction limit is surpassed in SH\nmicroscopic measurements. Electric field induced changes in SHG from individual\ngrains and/or domains of ferroelectric thin films have been observed.",
        "positive": "Raman Spectroscopy of Bi2Se3-xTex (x= 0 to 3) Topological Insulator\n  Crystals: We report crystal growth and Raman spectroscopy characterization of pure and\nmixed bulk topological insulators. The series comprises of both binary and\nternary tetradymite topological insulators. We analyzed in detail the Raman\npeaks of vibrational modes as out of plane Ag, and in plane Eg for both binary\nand ternary tetradymite topological insulators. Both out of plane Ag exhibit\nobvious atomic size dependent peak shifts and the effect is much lesser for the\nformer than the latter. The situation is rather interesting for in plane Eg,\nwhich not only shows the shift but rather a broader hump like structure. The de\nconvolution of the same show two clear peaks, which are understood in terms of\nthe presence of separate in plane BiSe and BiTe modes in mixed tetradymite\ntopological insulators. Summarily, various Raman modes of well-characterized\npure and mixed topological insulator single crystals are reported and discussed\nin this article."
    },
    {
        "anchor": "Spin wave excitations in exchange biased IrMn/CoFe bilayers: Using an atomistic spin model, we have simulated spin wave injection and\npropagation into antiferromagnetic IrMn from an exchange coupled CoFe layer.\nThe spectral characteristics of the exited spin waves have a complex beating\nbehavior arising from the non-collinear nature of the antiferromagnetic order.\nWe find that the frequency response of the system depends strongly on the\nstrength and frequency of oscillating field excitations. We also find that the\nstrength of excited spin waves strongly decays away from the interfacial layer\nwith a frequency dependent attenuation. Our findings suggest that spin waves\ngenerated by coupled ferromagnets are too weak to reverse IrMn in their\nentirety even with resonant excitation of a coupled ferromagnet. However,\nefficient spin wave injection into the antiferromagnet is possible due to the\nnon-collinear nature of the IrMn spin ordering.",
        "positive": "Two-dimensional InSe/WS$_2$ heterostructure with enhanced optoelectronic\n  performance in the visible region: Two-dimensional (2D) InSe and WS$_2$ exhibit promising characteristics for\noptoelectronic and photoelectrochemical applications, e.g. photodetection and\nphotocatalytic water splitting. However, both of them have poor absorption of\nvisible light due to wide band gaps. 2D InSe has high electron mobility but low\nhole mobility, while 2D WS$_2$ is on the opposite. Here, we design a 2D\nheterostructure composed of their monolayers and study its optoelectronic\nproperties by first-principles calculations. Our results show that the\nheterostructure has a direct band gap of 2.19 eV, which is much smaller than\nthose of the monolayers mainly due to a type-II band alignment: the valence\nband maximum and the conduction band minimum of monolayer InSe are lower than\nthose of monolayer WS$_2$, respectively. The visible-light absorption is\nenhanced considerably, e.g. about fivefold (threefold) increase at the\nwavelength of 490 nm in comparison to monolayer InSe (WS$_2$). The type-II band\nalignment also facilitates the spatial separation of photogenerated\nelectron-hole pairs, i.e., electrons (holes) reside preferably in the InSe\n(WS$_2$) layer. The two layers complement each other in carrier mobilities of\nthe heterostructure: the photogenerated electrons and holes inherit the large\nmobilities from the InSe and WS$_2$ monolayers, respectively."
    },
    {
        "anchor": "$\\mathrm{O_2}$ reduction at a DMSO/Cu(111) model battery interface: In order to develop a better understanding of electrochemical $\\mathrm{O_2}$\nreduction in non-aqueous solvents, we apply two-photon photoelectron\nspectroscopy to probe the dynamics of $\\mathrm{O_2}$ reduction at a\nDMSO/Cu(111) model battery interface. By analyzing the temporal evolution of\nthe photoemission signal, we observe the formation of $\\mathrm{O_2^-}$ from a\ntrapped electron state at the DMSO/vacuum interface. We find the vertical\nbinding energy of $\\mathrm{O_2^-}$ to be 3.80 $\\pm$ 0.05 eV, in good agreement\nwith previous results from electrochemical measurements, but with improved\naccuracy, potentially serving as a basis for future calculations on the\nkinetics of electron transfer at electrode interfaces. Modelling the\n$\\mathrm{O_2}$ diffusion through the DMSO layer enables us to quantify the\nactivation energy of diffusion (31 $\\pm$ 6 meV), the diffusion constant (1\n$\\pm$ 1$\\cdot 10^{-8}$ cm$^2$/s), and the reaction quenching distance for\nelectron transfer to $\\mathrm{O_2}$ in DMSO (12.4 $\\pm$ 0.4 $\\unicode{x212B}$),\na critical value for evaluating possible mechanisms for electrochemical side\nreactions. These results ultimately will inform the development and\noptimization of metal-air batteries in non-aqueous solvents.",
        "positive": "A new class of intrinsic magnet: two-dimensional yttrium sulphur\n  selenide: Exploring and controlling magnetism in two-dimensional (2D) layered magnetic\ncrystals, as well as their inclusion in heterogeneous assemblies, provide an\nunprecedented opportunity for fundamental science and technology. To date,\nhowever, there are only a few known intrinsic 2D magnets. Here we predict a\nnovel 2D intrinsic magnet, yttrium sulfur selenide (YSSe), using\nfirst-principles calculations. The magnetism of this transition metal\ndichalcogenide originates from the partially-filled $3p$- and $4p$-orbitals of\nthe chalcogens, unlike other known intrinsic magnets where magnetism arises\nfrom the partially-filled $3d$- and $4f$-orbitals. The unconventional magnetism\nin YSSe is a result of a unique combination of its structural and electronic\nproperties. We further show that a lack of mirror symmetry results in\npiezoelectric properties, while the broken space- and time-symmetry ensures\nvalley polarization. YSSe is a rare magnetic-piezoelectric material that can\nenable novel spintronics, valleytronics, and quantum technologies."
    },
    {
        "anchor": "On the nature of change in Ni oxidation state in BaTiO3-SrTiO3 system: XAFS studies of Ni-doped Ba$_{1-x}$Sr$_x$TiO$_3$ solid solution reveal that\nthe Ni oxidation state changes from 4 in SrTiO$_3$ to 2.5 in BaTiO$_3$ when\nvarying $x$. This change is accompanied by a noticeable change in the\ninteratomic Ni-O distances in the first shell. The first-principles\ncalculations show that nickel creates an impurity band in the forbidden band\ngap of BaTiO$_3$ and SrTiO$_3$, which explains the appearance of intense\nabsorption of Ni-doped samples in the visible region. The analysis of the\nelectronic structure of doped crystals and calculations of the oxygen vacancy\nformation energy in them show that different oxidation states of Ni in\nSrTiO$_3$ and BaTiO$_3$ can be explained by different formation energies of the\noxygen vacancies in these compounds.",
        "positive": "Direct and Scalable Chemical Vapor Deposition of Ultrathin Low-Noise\n  MoS2 Membranes on Apertures: We show that atomically thin molybdenum disulfide (MoS2) crystals can grow\nwithout any underlying substrates into free-standing atomically-thin layers,\nmaintaining their planar 2D form. Using this property, we present a new\nmechanism for 2D crystal synthesis, i.e. reagent-limited nucleation near an\naperture edge followed by reactions that allow crystal growth into the\nfree-space of the aperture. Such an approach enables us, for the first time,\nthe direct and selective growth of freestanding membranes of atomically thin\nMoS2 layers across micrometer-scale pre-fabricated solid-state apertures in\nSiNx membranes. Under optimal conditions, MoS2 grows preferentially across\napertures, resulting in sealed membranes that are one to a few atomic layers\nthick. Since our method involves free-space growth and is devoid of either\nsubstrates or transfer, it is conceivably the most contamination-free method\nfor obtaining 2D crystals reported so far. The membrane quality was\ninvestigated using atomic-resolution transmission electron microscopy, Raman\nspectroscopy, photoluminescence spectroscopy, and low-noise ion-current\nrecordings through nanopores fabricated in such membranes."
    },
    {
        "anchor": "Interplay between Phase Transformation Instabilities and Spatiotemporal\n  Reaction Heterogeneities in Particulate Intercalation Electrodes: Lithium-ion batteries rely on particulate porous electrodes to realize high\nperformance, especially the fast-charging capability. To minimize the\nparticle-wise reaction heterogeneities that may lead to local hot spots, deeper\nunderstandings of these electrodes at the mesoscale, i.e. hundreds of\nparticles, have become an urgent need. This study reveals that the seemingly\nrandom reaction heterogeneities are actually controlled by the interplay\nbetween the non-equilibrium material thermodynamics and the external\nelectrochemical driving force. Our operando experiments confirm the true\nworking current density around a single particle that is much higher than the\nglobally averaged current density, can change the behavior of phase\ntransformation. The combined theoretical and experimental analyses reveal that\nunlike other phase-transforming porous electrodes, not all phase separation\nprocesses in graphite can be suppressed at high currents, due to the\ncharacteristics of the concentration-dependent exchange current density. The\ninsights highlight the necessity to incorporate materials thermodynamics into\nelectrochemical models to ensure self-consistent understandings of practical\nporous electrodes toward precision design and management.",
        "positive": "Neutral defects in SrTiO3 studied with screened hybrid density\n  functional theory: The properties of neutral defects in SrTiO3 are calculated using the screened\nhybrid density functional of Heyd, Scuseria, and Ernzerhof. The formation\nenergies, the crystal field splittings affecting the SrTiO3 band structure, and\nthe relaxation geometries around each defect are discussed. Oxygen vacancies\nintroduced in SrTiO3 are found to cause a small tetragonal elongation of the\nlattice along the z-axis. The resulting conduction band minimum electron\neffective masses deviate from the bulk values and support the proposal of\nenhanced electron mobility along the direction of the compressive strain. The\nlocations of the various defect bands within the SrTiO3 gap are estimated\nwithout introducing any post hoc corrections, thus allowing a more reliable\ncomparison with experiment."
    },
    {
        "anchor": "Fermi surface tomography: Fermi surfaces, three-dimensional (3D) abstract interfaces that define the\noccupied energies of electrons in a solid, are important for characterizing and\npredicting the thermal, electrical, magnetic, and optical properties of\ncrystalline metals and semiconductors [1]. Angle-resolved photoemission\nspectroscopy (ARPES) is the only technique directly probing the Fermi surface\nby measuring the Fermi momenta (kF) from energy and angular distribution of\nphotoelectrons dislodged by monochromatic light [2]. Existing electron\nanalyzers are able to determine a number of kF-vectors simultaneously, but\ncurrent technical limitations prohibit a direct high-resolution 3D Fermi\nsurface mapping. As a result, no such datasets exist, strongly limiting our\nknowledge about the Fermi surfaces and restricting a detailed comparison with\nthe widely available nowadays calculated 3D Fermi surfaces. Here we show that\nusing a simpler instrumentation, based on the Fourier electron optics combined\nwith a retardation field of the detector, it is possible to perform 3D-mapping\nwithin a very short time interval and with very high resolution. We present the\nfirst detailed experimental 3D Fermi surface recorded in the full Brillouin\nzone along the kz-direction as well as other experimental results featuring\nmultiple advantages of our technique. In combination with various light\nsources, including synchrotron radiation, our methodology and instrumentation\noffer new opportunities for high-resolution ARPES in the physical and life\nsciences.",
        "positive": "Out-of-plane polarization and topological magnetic vortices in\n  multiferroic CrPSe$_3$: Two-dimensional (2D) multiferroic materials are ideal systems for exploring\nnew coupling mechanisms between different ferroic orders and producing novel\nquantum phenomena with potential applications. We employed first-principles\ndensity functional theory calculations to discover intrinsic ferroelectric and\nanti-ferroelectric phases of CrPSe$_3$, which show ferromagnetic order and\ncompete with the centrosymmetric phase with an antiferromagnetic order. Our\nanalysis show that the electrical dipoles of such type-I multiferroic phases\ncome from the out-of-plane displacements of phosphorus ions due to the\nstereochemically active lone pairs. The coupling between polar and magnetic\norders creates the opportunity for tunning the magnetic ground state by\nswitching from the centrosymmetric to the ferroelectric phase using an\nout-of-plane electric field. In ferroelectric and antiferroelectric phases, the\ncombination of easy-plane anisotropy and Dzyaloshinskii-Moriya interactions\n(DMI) indicate they can host topological magnetic vortices like meron pairs."
    },
    {
        "anchor": "Coupling quantum circuits to magnetic molecular qubits: This thesis explores the coupling of magnetic systems to quantum circuits in\nthe context of quantum computing applications. In particular we study the\ncoupling of superconducting coplanar waveguide resonators to Single Molecule\nMagnets (SMMs) . The combination of approaches from the fields of Cavity\nQuantum electrodynamics (QED) and Circuit QED with those from the field of\nmolecular magnetism con provide unique opportunities for quantum computing. We\ninvestigate the necessary conditions for coupling single spins and spin\nensembles to resonators and what characteristics SMMs should have in order to\nprovide interesting alternatives as quantum bits. We present test measurements\nof several magnetic samples using both broadband spectroscopy with open\nwaveguides and EPR spectroscopy using coplanar waveguide resonators. We also\ndesign, fabricate, and test nanometric constrictions in superconducting\nresonators with the objective of improving their coupling to single spins. We\nevaluate the performance of these constricted resonators in comparison to\nunmodified resonators.",
        "positive": "Structure-Dynamics Correlation in Metallic Glass Revealed by\n  5-Dimensional Scanning Transmission Electron Microscopy: Dynamic and structural heterogeneities play an important role in glass\ntransition phenomena and in the formation of amorphous structures. Since\nstructure and dynamics are mutually related, it is expected that there exists\nsome relation between them; however, this relation has not been characterized\nby a direct experiment. Elucidation of this relation is the key to identifying\nthe structure responsible for the rapid freezing of atomic motion during the\nglass transition. In this study, we simultaneously observed the dynamic and\nstructural heterogeneities near the glass transition temperature in\nZr50Cu40Al10 using five-dimensional scanning transmission electron microscopy,\nwhich is capable of recording the spatiotemporal distribution of electron\ndiffraction pattern. Dynamic and structural heterogeneities were visualized\nwith sub-nanometer resolution upon heating in situ, and a spatial correlation\nbetween them was observed up to the glass transition temperature. Simultaneous\nmeasurements of dynamic and structural heterogeneities directly revealed that\nthe ordered atomic structure had slow dynamics and that the order decreased\nwith temperature."
    },
    {
        "anchor": "Van der Waals bonding in layered compounds from advanced\n  first-principles calculations: Although the precise microscopic knowledge of van der Waals interactions is\ncrucial for understanding bonding in weakly bonded layered compounds, very\nlittle quantitative information on the strength of interlayer interaction in\nthese materials is available, either from experiments or simulations. Here,\nusing many-body perturbation and advanced density-functional theory techniques,\nwe calculate the interlayer binding and exfoliation energies for a large number\nof layered compounds and show that, independent of the electronic structure of\nthe material, the energies for most systems are around 20 meV/\\AA$^2$. This\nuniversality explains the successful exfoliation of a wide class of layered\nmaterials to produce two-dimensional systems, and furthers our understanding\nthe properties of layered compounds in general.",
        "positive": "Crossover of Three-Dimensional Topological Insulator of Bi2Se3 to the\n  Two-Dimensional Limit: Bi2Se3 is theoretically predicted1 2and experimentally observed2,3 to be a\nthree dimensional topological insulator. For possible applications, it is\nimportant to understand the electronic structure of the planar device. In this\nwork, thickness dependent band structure of molecular beam epitaxy grown\nultrathin films of Bi2Se3 is investigated by in situ angle-resolved\nphotoemission spectroscopy. An energy gap is observed for the first time in the\ntopologically protected metallic surface states of bulk Bi2Se3 below the\nthickness of six quintuple layers, due to the coupling between the surface\nstates from two opposite surfaces of the Bi2Se3 film. The gapped surface states\nexhibit sizable Rashba-type spin-orbit splitting, due to breaking of structural\ninversion symmetry induced by SiC substrate. The spin-splitting can be\ncontrolled by tuning the potential difference between the two surfaces."
    },
    {
        "anchor": "Interface-anisotropy induced asymmetry of intermixing in bilayers: The ion-sputtering induced intermixing is studied by molecular dynamics (MD)\nsimulations and by Auger electron spectroscopy depth profiling (AES-DP)\nanalysis in Pt/Ti/Si substrate (Pt/Ti) and Ta/Ti/Pt/Si substrate (Ti/Pt)\nmultilayers. Experimental evidence is found for the asymmetry of intermixing in\nPt/Ti and in Ti/Pt. An unexpected enhancement of the injection of the heavy Pt\natoms into the Ti substrate is observed both by AES-DP and by MD simulations.\nIn Ti/Pt we get a much weaker interdiffusion than in Pt/Ti. The asymmetry is\nexplained by the backscattering of hyperthermal particles at the\nmass-anisotropic interface and which is reproduced by computer atomistic\nsimulations. The AES-DP measurements support our earlier predictions (P.\nS\\\"ule, M. Menyh\\'ard, Phys. Rev., {\\bf B71}, 113413 (2005)) obtained for\nmass-anisotropic bilayers.",
        "positive": "Carbon Irradiated SI-GaAs for Photoconductive THz Detection: We report here a photoconductive material for THz generation and detection\nwith sub-picosecond carrier lifetime made by C12 (Carbon) irradiation on\ncommercially available semi-insulating (SI) GaAs. We are able to reduce the\ncarrier lifetime of SI-GaAs down to sub-picosecond by irradiating it with\nvarious irradiation dosages of Carbon (C12) ions. With an increase of the\nirradiation dose from ~1012 /cm2 to ~1015 /cm2 the carrier lifetime of SI-GaAs\nmonotonously decreases to 0.55 picosecond, resulting in strongly improved THz\npulse detection compared with normal SI-GaAs."
    },
    {
        "anchor": "Nano-Graphene Oxide for Cellular Imaging and Drug Delivery: Two-dimensional graphene offers interesting electronic, thermal and\nmechanical properties that are currently explored for advanced electronics,\nmembranes and composites. Here we synthesize and explore the biological\napplication of nano-graphene oxide NGO, single-layer graphene oxide sheets down\nto a few nanometers in lateral width. We develop functionalization chemistry to\nimpart solubility and compatibility of NGO in biological environments. We\nobtain size separated pegylated NGO sheets that are soluble in buffers and\nserum without agglomeration. The NGO sheets are found to be photoluminescent in\nthe visible and infrared regions. The intrinsic photoluminescence of NGO is\nused for live cell imaging in the near-infrared with little background. We\nfound that simple physisorption via pi-stacking can be used for loading\ndoxorubicin, a widely used cancer drug onto NGO functionalized with antibody\nfor selective cancer cell killing in vitro. Owing to the small size, intrinsic\noptical properties, large specific surface area,low cost, and useful\nnon-covalent interactions with aromatic drug molecules, NGO is a promising new\nmaterial for biological and medical applications.",
        "positive": "Transverse thermoelectric effect in La0.67Sr0.33MnO3|SrRuO3\n  superlattices: Transverse thermoelectric effects in response to an out-of-plane heat current\nhave been studied in an external magnetic field for ferromagnetic superlattices\nconsisting of La0.67Sr0.33MnO3 and SrRuO3 layers. The superlattices were\nfabricated on SrTiO3 substrates by pulsed laser deposition. We found that the\nsign of the transverse thermoelectric voltage for the superlattices is opposite\nto that for La0.67Sr0.33MnO3 and SrRuO3 single layers at 200 K, implying an\nimportant role of spin Seebeck effects inside the superlattices. At 10 K, the\nmagnetothermoelectric curves shift from the zero field due to an\nantiferromagnetic coupling between layers in the superlattices."
    },
    {
        "anchor": "Gap and spin texture engineering of Dirac topological states at the\n  Cr-Bi$_2$Se$_3$ interface: The presence of an exchange field in topological insulators reveals novel\nspin related phenomena derived from the combination of topology and magnetism.\nIn the present work we show the controlled occurrence of either metallic or\ngapped topological Dirac states at the interface between ultrathin Cr films and\nthe Bi$_2$Se$_3$ surface. The opening and closing of the gap at the Dirac point\nis caused by the spin reorientation transitions arising in the Cr films. We\nfind that atom thin layers of Cr adhered to Bi$_2$Se$_3$ surfaces present a\nmagnetic ground state with ferromagnetic planes coupled antiferromagnetically.\nAs the thickness of the Cr film increases stepwise from one to three atomic\nlayers, the direction of the magnetization changes twice from out-of-plane to\nin-plane and to out-of-plane again. The out of plane magnetization drives the\ngap opening and the topological surface states acquire a circular meron spin\nstructure. Therefore, the Cr spin reorientation leads to the metal/insulator\ntransition in the Bi$_2$Se$_3$ surface and to the correlated modification of\nthe surface state spin texture. Consequently, the thickness of the Cr film\nprovides an effective and controllable mechanism to modify the metallic or\ngapped nature, as well as the spin texture of the topological Dirac states.",
        "positive": "Concept study for a high-efficiency nanowire-based thermoelectric: Materials capable of highly efficient, direct thermal-to-electric energy\nconversion would have substantial economic potential. Theory predicts that\nthermoelectric efficiencies approaching the Carnot limit can be achieved at low\ntemperatures in one-dimensional conductors that contain an energy filter such\nas a double-barrier resonant tunneling structure. The recent advances in growth\ntechniques suggest that such devices can now be realized in heterostructured,\nsemiconductor nanowires. Here we propose specific structural parameters for\nInAs/InP nanowires that may allow the experimental observation of near-Carnot\nefficient thermoelectric energy conversion in a single nanowire at low\ntemperature."
    },
    {
        "anchor": "Enhancing the Adhesion of Graphene to Polymer Substrates by Controlled\n  Defect Formation: The mechanical integrity of composite materials depends primarily on the\ninterface strength and the defect density of the reinforcement which is the\nprovider of enhanced strength and stiffness. In the case of graphene/ polymer\nnanocomposites which are characterized by an extremely large interface region,\nany defects in the inclusion (such as folds, cracks, holes etc.) will have a\ndetrimental effect to the internal strain distribution and the resulting\nmechanical performance. This conventional wisdom, however, can be challenged if\nthe defect size is reduced beyond the critical size for crack formation to the\nlevel of atomic vacancies. In that case, there should be no practical effect on\ncrack propagation and depending on the nature of the vacancies the interface\nstrength may be in fact increase. In this work we employed argon ion (Ar+)\nbombardment and subsequent exposure to hydrogen (H2) to induce (as revealed by\nX-ray & Ultraviolet photoelectron spectroscopy (XPS/UPS) and Raman\nspectroscopy) passivated atomic single vacancies to CVD graphene. The modified\ngraphene was subsequently transferred to PMMA bars and the morphology,\nwettability and the interface adhesion of the CVD graphene/PMMA system were\ninvestigated with Atomic Force Microscopy technique and Raman analysis. The\nresults obtained showed clearly an overall improved mechanical behavior of\ngraphene/polymer interface, since an increase as well a more uniform shift\ndistribution with strain is observed. This paves the way for interface\nengineering in graphene/polymer systems which, in pristine condition, suffer\nfrom premature graphene slippage and subsequent failure.",
        "positive": "Electronic chemical potentials of porous metal-organic frameworks: The binding energy of an electron in a material is a fundamental\ncharacteristic, which determines a wealth of important chemical and physical\nproperties. For metal-organic frameworks this quantity is hitherto unknown. We\npresent a general approach for determining the vacuum level of porous\nmetal-organic frameworks and apply it to obtain the first ionisation energy for\nsix prototype materials including zeolitic, covalent and ionic frameworks. This\napproach for valence band alignment can explain observations relating to the\nelectrochemical, optical and electrical properties of porous frameworks."
    },
    {
        "anchor": "Surface effects on the electronic energy loss of charged particles\n  entering a metal surface: Surface effects on the electronic energy loss of charged particles entering a\nmetal surface are investigated within linear-response theory, in the framework\nof time-dependent density functional theory. Interesting phenomena occur in the\nloss spectra originated by the boundary (bregenzung) effect, which is as a\nconsequence of the orthogonality of surface and bulk excitation modes. Our\ncalculations indicate that the presence of a non-abrupt electron-density\nprofile at the surface severely affects the nature of surface excitations, as\ndeduced from comparison with simplified models.",
        "positive": "Relaxation volumes of microscopic and mesoscopic irradiation-induced\n  defects in tungsten: The low energy structures of irradiation-induced defects have been studied in\ndetail, as these determine the available modes by which a defect can diffuse or\nrelax. As a result, there are many studies concerning the relative energies of\npossible defect structures, and empirical potentials are commonly fitted to or\nevaluated with respect to these energies. But recently [Dudarev et al Nuclear\nFusion 2018], we have shown how to determine the stresses, strains and swelling\nof reactor components under irradiation from the elastic properties of\nensembles of irradiation-induced defects. These elastic properties have\nreceived comparatively little attention. Here we evaluate relaxation volumes of\nirradiation-induced defects in tungsten computed with empirical potentials, and\ncompare to density functional theory results where available. Different\nempirical potentials give different results, but some potential-independent\ntrends in relaxation volumes can be identified. We show that the relaxation\nvolume of small defects can be predicted to within 10% from their point-defect\ncount. For larger defects we provide empirical fits for the relaxation volume\nof as a function of size. We demonstrate that the relaxation volume associated\nwith a single primary-damage cascade can be estimated from the primary knock-on\natom (PKA) energy. We conclude that while annihilation of vacancy- and\ninterstitial- character defects will invariably reduce the total relaxation\nvolume of the cascade debris, empirical potentials disagree whether coalescence\nof defects will reduce or increase the total relaxation volume."
    },
    {
        "anchor": "Role of intermetallic phases in initiation and propagation of\n  intergranular corrosion of an Al-Li-Cu-Mg alloy: Intermetallic phases in a recently developed Al-Li-Cu-Mg alloy have been\ninvestigated to understand their roles in the initiation and propagation\nprocesses of intergranular corrosion. Corrosion initiation involves trenching\nformation in the Al matrix adjacent to the large particles of Al7Cu2(Fe, Mn)\nphases. These phases containing Li are electrochemically active and susceptible\nto self-dissolution via a de-alloying mechanism during corrosion process. The\nsubsurface particles of Al7Cu2(Fe, Mn) and Al20Cu2Mn3 phases act as the\ninternal cathodes for continuous corrosion propagation along the\nparticle-matrix interface and the associated grain boundaries. Corrosion\npropagation along the particle-matrix interface was facilitated by the anodic\ndissolution of the surrounding Al matrix due to the micro-galvanic interaction\nwith the cathodic intermetallic phases. In addition, T1 (Al2CuLi) precipitates\nand the isolated particles of Al7Cu2(Fe, Mn) and Al20Cu2Mn3 phases were\ndissolved along the path of corrosion propagation. The dissolved metal ions\nwere redeposited through the network of crevice.",
        "positive": "Tunable intrinsic ferromagnetic topological phases in bulk van der Waals\n  crystal MnSb6Te10: Intrinsic ferromagnetism is a crucial ingredient to realize quantum anomalous\nHall effect in quasi two dimensional materials, thus the search of intrinsic\nferromagnetic topological materials is one of the most concerned issues in the\nfield of topological phases of matter. In this work, combining magnetotransport\nmeasurements, first principles calculations, and angle-resolved photoemission\nspectroscopy studies, we find that in MnSb6Te10, the n = 2 member of the\nMnSb2Te4/(Sb2Te3)n family, the strong magnetic competition realizes a fragile\nferromagnetic ground state, which whereas easily enters into ferrimagnetic and\nthe Z_2 antiferromagnetic topological insulator phase with warming to higher\ntemperature. Interestingly, the system stays in an inversion-symmetry-protected\naxion insulator phase in the ferromagnetic ground state as well as in the\nexternal magnetic field driven spin-polarized FM phase and can be converted\ninto a Weyl semimetal with multiple Weyl nodes in the valence bands with hole\ndoping, which are manifested by the measured notable intrinsic anomalous Hall\neffect. Our work thus provides an intrinsic magnetic topological material which\nis highly tunable into versatile topological phases by temperature, magnetic\nfield, as well as carrier doping."
    },
    {
        "anchor": "Fully parameter-free calculation of optical spectra for insulators,\n  semiconductors and metals from a simple polarization functional: We present a fully parameter-free density-functional approach for the\naccurate description of optical absorption spectra of insulators,\nsemiconductors and metals. We show that this can be achieved within\ntime-dependent current-density-functional theory using a simple dynamical\npolarization functional. We derive this functional from physical principles\nthat govern optical spectra. Our method is truly predictive because not a\nsingle parameter is used. In particular, we do not use an \\textit{ad-hoc}\nmaterial-dependent broadening parameter to compare theory to experiment as is\nusually done. Our approach is numerically efficient; the cost equals that of a\ncalculation within the random-phase approximation.",
        "positive": "Polarons, free charge localisation and effective dielectric permittivity\n  in oxides: This review will deal with several types of free charge localisation in\noxides and their consequences on the effective dielectric spectra of such\nmaterials. The first one is the polaronic localisation at the unit cell scale\non residual impurities in ferroelectric networks. The second one is the\ncollective localisation of free charge at macroscopic interfaces like surfaces,\nelectrodes and grain boundaries in ceramics. Polarons have been observed in\nmany oxide perovskites mostly when cations having several stable electronic\nconfigurations are present. In manganites, the density of such polarons is so\nhigh as to drive a net lattice of interacting polarons. On the other hand, in\nferroelectric materials like BaTiO3 and LiNbO3, the density of polarons is\nusually very small but they can influence strongly the macroscopic\nconductivity. The contribution of such polarons to the dielectric spectra of\nferroelectric materials is described. Even residual impurities as for example\nIron can induce well defined anomalies at very low temperatures. This is mostly\nresulting from the interaction between localised polarons and the highly\npolarisable ferroelectric network in which they are embedded. The case of such\nresidual polarons in SrTiO3 will be described in more details, emphasizing the\nquantum polaron state at liquid helium temperatures. Recently, several\nnon-ferroelectric oxides have been shown to display giant effective dielectric\npermittivity. It is first shown that the frequency/temperature behaviour of\nsuch parameters is very similar in very different compounds (donor doped\nBaTiO3, CaCu3Ti4O12, LuFe2O4,Li doped NiO,...). This similarity calls for a\ncommon origin of the giant dielectric permittivity in these compounds. A space\ncharge localisation at macroscopic interfaces can be the key for such extremely\nhigh dielectric permittivity."
    },
    {
        "anchor": "Symmetry of the carbon nanotube modes and their origin from the phonon\n  branches of graphene: A new group-theory method to relate a spectrum of carbon nanotubes with that\nof a graphene monolayer is elaborated. The spectrum reconstruction is performed\nusing a virtual intermediate planar periodic structure. Selected irreducible\nrepresentations of its space symmetry group and all those of the nanotube one\nare isomorphic and therefore span the correlated excitations. The method is\napplied to study the origin of the zone-center phonon modes of chiral and\nachiral carbon nanotubes. The structure of the G-band for particular types of\nnanotubes is determined. The results obtained could be useful for experimental\nindexing of the carbon nanotubes by means of Raman spectroscopy.",
        "positive": "Symmetry-broken crystal structure of elemental boron at low temperature: The crystal structure of boron is unique among chemical elements, highly\ncomplex, and imperfectly known. Experimentalists report the beta-rhombohedral\n(black) form is stable over all temperatures from absolute zero to melting.\nHowever, early calculations found its energy to be greater than the energy of\nthe alpha-rhombohedral (red) form, implying beta cannot be stable at low\ntemperatures. Furthermore, beta exhibits partially occupied sites, seemingly in\nconflict with the thermodynamic requirement that entropy vanish at low\ntemperature. Using electronic density functional theory methods and an\nextensive search of the configuration space we find a unique, energy minimizing\npattern of occupied and vacant sites that can be stable at low temperatures but\nthat breaks the beta-rhombohedral symmetry. Even lower energies occur within\nlarger unit cells. Alternative configurations lie nearby in energy, allowing\nthe entropy of partial occupancy to stabilize the beta-rhombohedral structure\nthrough a phase transition at moderate temperature."
    },
    {
        "anchor": "Energy derivatives in real-space diffusion Monte Carlo: We present unbiased, finite--variance estimators of energy derivatives for\nreal--space diffusion Monte Carlo calculations within the fixed--node\napproximation. The derivative $d_\\lambda E$ is fully consistent with the\ndependence $E(\\lambda)$ of the energy computed with the same time step. We\naddress the issue of the divergent variance of derivatives related to\nvariations of the nodes of the wave function, both by using a regularization\nfor wave function parameter gradients recently proposed in variational Monte\nCarlo, and by introducing a regularization based on a coordinate\ntransformation. The essence of the divergent variance problem is distilled into\na particle-in-a-box toy model, where we demonstrate the algorithm.",
        "positive": "Importance of non-local electron correlations in BaNiS$_{2}$ semimetal\n  from quantum oscillations studies: By means of Shubnikov-de-Haas and de-Haas-van-Alphen oscillations, and ab\ninitio calculations, we have studied the Fermi surface of high-quality\nBaNiS$_2$ single crystals, with mean free path $l \\sim 400 ~\\text{\\AA}$. The\nangle and temperature dependence of quantum oscillations indicates a\nquasi-two-dimensional Fermi surface, made of an electron-like tube centred at\n$\\Gamma$, and of 4 hole-like cones, generated by Dirac bands, weakly dispersive\nin the out-of-plane direction. Ab initio electronic structure calculations, in\nthe density functional theory framework, show that the inclusion of screened\nexchange is necessary to account for the experimental Fermi pockets. Therefore,\nthe choice of the functional becomes crucial. A modified HSE hybrid functional\nwith 7% of exact exchange outperforms both GGA and GGA+U density functionals,\nsignalling the importance of non-local screened-exchange interactions in\nBaNiS$_2$, and, more generally, in $3d$ compensated semimetals."
    },
    {
        "anchor": "Interaction of highly nonlinear solitary waves with linear elastic media: We study the interaction of highly nonlinear solitary waves in granular\ncrystals, with an adjacent linear elastic medium. We investigate the effects of\ninterface dynamics on the reflection of incident waves and on the formation of\nprimary and secondary reflected waves. Experimental tests are performed to\ncorrelate the linear medium geometry, materials, and mass with the formation\nand propagation of the reflected waves. We compare the experimental results\nwith theoretical analysis based on the long-wavelength approximation and with\nnumerical predictions obtained from discrete particle models. Studying\nvariations of the reflected wave's velocity and amplitude, we describe how the\npropagation of primary and secondary reflected waves responds sensitively to\nthe states of the adjacent linear media. Experimental results are found to be\nin agreement with the theoretical analysis and numerical simulation. This\npreliminary study establishes the foundation for utilizing reflected solitary\nwaves as novel information carriers in nondestructive evaluation of elastic\nmaterial systems.",
        "positive": "Properties of real metallic surfaces: Effects of density functional\n  semilocality and van der Waals nonlocality: We have computed the surface energies, work functions, and interlayer surface\nrelaxations of clean (111), (110), and (100) surfaces of Al, Cu, Ru, Rh, Pd,\nAg, Pt, and Au. Many of these metallic surfaces have technological or catalytic\napplications. We compare experimental reference values to those of the local\ndensity approximation (LDA), the Perdew-Burke-Ernzerhof (PBE) generalized\ngradient approximation (GGA), the PBEsol (PBE for solids) GGA, the SCAN\nmeta-GGA, and SCAN+rVV10 (SCAN with a long-range van der Waals or vdW\ncorrection). The closest agreement with uncertain experimental values is\nachieved by the simplest density functional (LDA) and by the most sophisticated\ngeneral-purpose one (SCAN+rVV10). The long-range vdW interaction increases the\nsurface energies by about 10%, and the work functions by about 1%. LDA works\nfor metal surfaces through a stronger-than-usual error cancellation. PBE yields\nthe most-underestimated and presumably least accurate surface energies and work\nfunctions. Surface energies within the random phase approximation (RPA) are\nalso reported. Interlayer relaxations from different functionals are in\nreasonable agreement with one another, and usually with experiment."
    },
    {
        "anchor": "Comments on the paper Growth and Characterization of Pure and\n  Thiourea-Doped L-Alanine Single Crystals for NLO Devices: we show that the pure and thiourea-doped glycyl-L-alanine hydrochloride (GLAH\nand TU-GLAH) crystals claimed to have been grown by the authors of the title\npaper (Journal of Russian Laser Research, 34, 346-350 (2013)) are dubious\ncrystals.",
        "positive": "Shear relaxation behind the shock front in $\\langle$110$\\rangle$\n  Molybdenum - From the Atomic Scale to Continuous Dislocation Fields: In this work we study shock-induced plasticity in Mo single crystals,\nimpacted along the <110> crystal orientation. In particular, the shear\nrelaxation behind the shock front is quantitatively inspected. Molecular\ndynamics (MD) simulations are employed to simulate the deformation during\nshock, followed by post-processing to identify and quantify the dislocation\nlines nucleated behind the shock front. The information on the dislocation\nlines is ensemble averaged inside slabs of the simulation box and over\ndifferent realizations of the MD simulations, from which continuous dislocation\nfields are extracted using the Discrete-to-Continuous method. The continuous\ndislocation fields are correlated with the stress and strain fields obtained\nfrom the MD simulations. Based on this analysis, we show that the elastic\nprecursor overshoots the shear stress, after which dislocations on a specific\ngroup of slip planes are nucleated, slightly lagging behind the elastic front.\nConsequently, the resolved shear stress is relaxed, but the principal lateral\nstress increases. The latter leads to an increase in the resolved shear stress\non a plane parallel to the shock wave, resulting in an additional retarded\nfront of dislocation nucleation on planes parallel to the shock front. Finally,\nthe two-stage process of plasticity results in an isotropic stress state in the\nplane parallel to the shock wave. The MD simulation results are employed to\ncalculate the dislocation densities on specific slip planes and the plastic\ndeformation behind the shock, bridging the gap between the information on the\natomic scale and the continuum level."
    },
    {
        "anchor": "Micropillar compression of single crystal tungsten carbide, Part 2:\n  Lattice rotation axis to identify deformation slip mechanisms: The plastic deformation mechanisms of tungsten carbide at room and elevated\ntemperatures influence the wear and fracture properties of WC-Co hardmetal\ncomposite materials. The relationship between residual defect structures,\nincluding glissile and sessile dislocations and stacking faults, and the slip\ndeformation activity, which produce slip traces, is not clear. Part 1 of this\nstudy showed that {10-10} was the primary slip plane at all measured\ntemperatures and orientations, but secondary slip on the basal plane was\nactivated at 600 {\\deg}C, which suggests that <a> dislocations can cross-slip\nonto the basal plane at 600 {\\deg}C. In the present work, Part 2, lattice\nrotation axis analysis of deformed WC micropillar mid-sections was used to\ndiscriminate <a> prismatic slip from multiple <c+a> prismatic slip in WC, which\nenabled the dislocation types contributing to plastic slip to be distinguished,\nindependently of TEM residual defect analysis. Prismatic-oriented micropillars\ndeformed primarily by multiple <c+a> prismatic slip at room temperature, but by\n<a> prismatic slip at 600 {\\deg}C. Deformation in the near-basal oriented\npillar at 600 {\\deg}C can be modelled as prismatic slip along <c> constrained\nby the indenter face and pillar base. Secondary <a> basal slip, which was\nobserved near the top of the pillar, was activated to maintain deformation\ncompatibility with the indenter face. The lattice rotations, buckled pillar\nshape, mechanical data, and slip traces observed in the pillar are all\nconsistent with this model.",
        "positive": "Nanoscale imaging of unusual photo-acoustic waves in thin flake VTe$_2$: Controlling acoustic phonons, the carriers of sound and heat, has been\nattracting great attention toward the manipulation of sonic and thermal\nproperties in nanometric devices. In particular, the photo-acoustic effect\nusing ultrafast optical pulses has a promising potential to optically\nmanipulate phonons in picoseconds time regime. However, its mechanism has been\nso far mostly based on the commonplace thermoelastic expansion in isotropic\nmedia, limiting the spectrum of potential applications. We investigate a\nconceptually new mechanism of photo-acoustic effect involving the structural\ninstability, by utilizing a transition-metal dichalcogenide VTe$_2$ with the\nribbon-type charge-density-wave (CDW). Ultrafast electron microscope imaging\nand diffraction measurements reveal the generation and propagation of unusual\nacoustic waves in the nanometric thin plate associated with the optically\ninduced instantaneous charge-density-wave dissolution. Our results highlight\nthe capability of photo-induced structural instability as a source of coherent\nacoustic waves."
    },
    {
        "anchor": "Ultrafast Modification of the Polarity at LaAlO$_3$/SrTiO$_3$ Interfaces: Oxide growth with semiconductor-like accuracy has led to atomically precise\nthin films and interfaces that exhibit a plethora of phases and functionalities\nnot found in the oxide bulk material. This yielded spectacular discoveries such\nas the conducting, magnetic or even superconducting LaAlO$_3$/SrTiO$_3$\ninterfaces separating two prototypical insulating perovskite materials. All\nthese investigations, however, consider the static state at the interface,\nalthough studies on fast oxide interface dynamics would introduce a powerful\ndegree of freedom to understanding the nature of the LaAlO$_3$/SrTiO$_3$\ninterface state. Here we show that the polarization state at the\nLaAlO$_3$/SrTiO$_3$ interface can be optically enhanced or attenuated within\npicoseconds. Our observations are explained by a model based on charge\npropagation effects in the interfacial vicinity and transient polarization\nbuildup at the interface.",
        "positive": "On the reliability of various enhancement theories for a description of\n  electron-positron densities in metals: Four theoretical approaches to calculate momentum densities of\nelectron-positron annihilation pairs (MDAP) in crystalline solids are\nconfronted with 3D densities reconstructed from two-dimensional angular\ncorrelation (2D-ACAR) data for copper, chromium, and yttrium. It is shown that\nthe Bloch-modified ladder theory, in contrast to other approaches, is able to\ndescribe - at least qualitatively - the MDAP profiles for all metals\ninvestigated."
    },
    {
        "anchor": "Pressure-Induced Enhancement of the Magnetic Anisotropy in\n  Mn(N(CN)$_{2}$)$_{2}$: Using dc and ac magnetometry, the pressure dependence of the magnetization of\nthe three-dimensional antiferromagnetic coordination polymer\nMn(N(CN)$_{2}$)$_{2}$ was studied up to 12 kbar and down to 8K. The magnetic\ntransition temperature, $T_c$, increases dramatically with applied pressure\n$(P)$, where a change from $T_c(P=\\text{ambient}) = 16.0$ K to\n$T_c(P=12.1$~kbar$) = 23.5$ K was observed. In addition, a marked difference in\nthe magnetic behavior is observed above and below 7.1 kbar. Specifically, for\n$P<7.1$ kbar, the differences between the field-cooled and zero-field-cooled\n(fc-zfc) magnetizations, the coercive field, and the remanent magnetization\ndecrease with increasing pressure. However, for $P>7.1$ kbar, the behavior is\ninverted. Additionally, for $P>8.6$ kbar, minor hysteresis loops are observed.\nAll of these effects are evidence of the increase of the superexchange\ninteraction and the appearance of an enhanced exchange anisotropy with applied\npressure.",
        "positive": "Offsets and polarization at strained AlN/GaN polar interfaces: The strain induced by lattice mismatch at the interface is responsible for\nthe different value of the band discontinuities observed recently for the\nAlN/GaN (AlN on GaN) and the GaN/AlN (GaN on AlN) polar (0001) interface. We\npresent a first-principles calculation of valence band offsets, interface\ndipoles, strain-induced piezoelectric fields, relaxed geometric structure, and\nformation energies. Our results confirm the existence of a large\nforward-backward asymmetry for this interface."
    },
    {
        "anchor": "Linear complexions directly modify dislocation motion in face-centered\n  cubic alloys: Linear complexions are defect phases that form in the presence of\ndislocations and thus are promising for the direct control of plasticity. In\nthis study, atomistic simulations are used to model the effect of linear\ncomplexions on dislocation-based mechanisms for plasticity, demonstrating\nunique behaviors that differ from classical dislocation glide mechanisms.\nLinear complexions impart higher resistance to the initiation and continuation\nof dislocation motion when compared to solid solution strengthening in all of\nthe face-centered cubic alloys investigated here, with the exact strengthening\nlevel determined by the linear complexion type. Stacking fault linear\ncomplexions impart the most pronounced strengthening effect, as the dislocation\ncore is delocalized, and initiation of plastic flow requires a dislocation\nnucleation event. The nanoparticle and platelet array linear complexions impart\nstrengthening by acting as pinning sites for the dislocations, where the\ndislocations unpin one at a time through bowing mechanisms. For the\nnanoparticle arrays, this event occurs even though the obstacles do not cross\nthe slip plane and instead only interact through modification of the\ndislocation's stress field. The bowing modes observed in the current work\nappear similar to traditional Orowan bowing around classical precipitates but\ndiffer in a number of important ways depending on the complexion type. As a\nwhole, this study demonstrates that linear complexions are a unique tool for\nmicrostructure engineering that can allow for the creation of alloys with new\nplastic deformation mechanisms and extreme strength.",
        "positive": "Misfit strain-induced buckling for transition-metal dichalcogenide\n  lateral heterostructures: a molecular dynamics study: Molecular dynamics simulations are performed to investigate the misfit\nstrain-induced buckling of the transition-metal dichalcogenide (TMD) lateral\nheterostructures, denoted by the seamless epitaxial growth of different TMDs\nalong the in-plane direction. The Stillinger-Weber potential is utilized to\ndescribe both the interaction for each TMD and the coupling between different\nTMDs, i.e., MX2 (with M=Mo, W and X=S, Se, Te). It is found that the misfit\nstrain can induce strong buckling of the free-standing TMD lateral\nheterostructures of large area, resulting from the TMDs' atomic-thick nature.\nThe buckling phenomenon occurs in a variety of TMD lateral heterostructures of\ndifferent compositions and in various patterns. Our findings raise a\nfundamental mechanical challenge for the structural stability of the\nfree-standing TMD lateral heterostructures."
    },
    {
        "anchor": "Structure and Dynamics of Boron Nitride Nanoscrolls: Carbon nanoscrolls (CNSs) are structures formed by rolling up graphene layers\ninto a papyruslike shape. CNNs have been experimentally produced by different\ngroups. Boron nitride nanoscrolls (BNNSs) are similar structures using boron\nnitride instead of graphene layers. In this work we report molecular mechanics\nand molecular dynamics results for the structural and dynamical aspects of BNNS\nformation. Similarly to CNS, BNNS formation is dominated by two major energy\ncontributions, the increase in the elastic energy and the energetic gain due to\nvan der Waals interactions of the overlapping surface of the rolled layers. The\narmchair scrolls are the most stable configuration while zigzag scrolls are\nmetastable structures which can be thermally converted to armchair. Chiral\nscrolls are unstable and tend to evolve to zigzag or armchair configurations\ndepending on their initial geometries. The possible experimental routes to\nproduce BNNSs are also addressed.",
        "positive": "Electronic structure and magnetic properties of Mn and Fe impurities\n  near GaAs (110) surface: Combining density-functional theory calculations and microscopic\ntight-binding models, we investigate theoretically the electronic and magnetic\nproperties of individual substitutional transition-metal impurities (Mn and Fe)\npositioned in the vicinity of the (110) surface of GaAs. For the case of the\n$[\\rm Mn^{2+}]^0$ plus acceptor-hole (h) complex, the results of a\ntight-binding model including explicitly the impurity $d$-electrons are in good\nagreement with approaches that treat the spin of the impurity as an effective\nclassical vector. For the case of Fe, where both the neutral isoelectronic\n$[\\rm Fe^{3+}]^0$ and the ionized $[\\rm Fe^{2+}]^-$ states are relevant to\naddress scanning tunneling microscopy (STM) experiments, the inclusion of\n$d$-orbitals is essential. We find that the in-gap electronic structure of Fe\nimpurities is significantly modified by surface effects. For the neutral\nacceptor state $[{\\rm Fe}^{2+}, h]^0$, the magnetic-anisotropy dependence on\nthe impurity sublayer resembles the case of $[{\\rm Mn}^{2+}, h]^0$. In\ncontrast, for $[{\\rm Fe}^{3+}]^{0}$ electronic configuration the magnetic\nanisotropy behaves differently and it is considerably smaller. For this state\nwe predict that it is possible to manipulate the Fe moment, e.g. by an external\nmagnetic field, with detectable consequences in the local density of states\nprobed by STM."
    },
    {
        "anchor": "Extending intergranular normal-stress distributions using symmetries of\n  linear-elastic polycrystalline materials: Intergranular normal stresses (INS) are critical in the initiation and\nevolution of grain boundary damage in polycrystalline materials. To model the\neffects of such microstructural damage on a macroscopic scale, knowledge of INS\nis usually required statistically at each representative volume element\nsubjected to various loading conditions. However, calculating INS distributions\nfor different stress states can be cumbersome and time-consuming. This study\nproposes a new method to extend the existing INS distributions to arbitrary\nloading conditions using the symmetries of a polycrystalline material composed\nof randomly oriented linear-elastic grains with arbitrary lattice symmetry. The\nmethod relies on a fact that INS distributions can be accurately reproduced\nfrom the first (typically) ten statistical moments, which depend trivially on\njust three stress invariants and a few material invariants due to assumed\nisotropy and material linearity of the polycrystalline model. While these\nmaterial invariants are complex averages, they can be extracted numerically\nfrom a few existing INS distributions and tabulated for later use. Practically,\nonly three such INS distributions at properly selected loadings are required to\nprovide all relevant material invariants for the first 11 statistical moments,\nwhich can then be used to reconstruct the INS distribution for arbitrary\nloading conditions. The proposed approach is demonstrated to be accurate and\nfeasible for an arbitrarily selected linear-elastic material under various\nloading conditions.",
        "positive": "Growth of nanostructures by cluster deposition : a review: This paper presents a comprehensive analysis of simple models useful to\nanalyze the growth of nanostructures obtained by cluster deposition. After\ndetailing the potential interest of nanostructures, I extensively study the\nfirst stages of growth (the submonolayer regime) by kinetic Monte-Carlo\nsimulations. These simulations are performed in a wide variety of experimental\nsituations : complete condensation, growth with reevaporation, nucleation on\ndefects, total or null cluster-cluster coalescence... The main scope of the\npaper is to help experimentalists analyzing their data to deduce which of those\nprocesses are important and to quantify them. A software including all these\nsimulation programs is available at no cost on request to the author. I\ncarefully discuss experiments of growth from cluster beams and show how the\nmobility of the clusters on the surface can be measured : surprisingly high\nvalues are found. An important issue for future technological applications of\ncluster deposition is the relation between the size of the incident clusters\nand the size of the islands obtained on the substrate. An approximate formula\nwhich gives the ratio of the two sizes as a function of the melting temperature\nof the material deposited is given. Finally, I study the atomic mechanisms\nwhich can explain the diffusion of the clusters on a substrate and the result\nof their mutual interaction (simple juxtaposition, partial or total\ncoalescence...)"
    },
    {
        "anchor": "Nonlinear optical properties of undoped and doped with Zr and Nb KTiOPO4\n  crystals: The structure of the ferroelectric phase of undoped KTiOPO$_4$ and its solid\nsolutions with zirconium and niobium is studied from first principles within\nthe density functional theory. The second-order nonlinear susceptibility tensor\nand the spontaneous polarization of these materials are obtained. It is shown\nthat an improvement in nonlinear optical properties of KTiOPO$_4$ upon its\ndoping with Zr and Nb cannot be explained by a systematic change in the\ncomposition of crystals and is apparently associated with the occurrence of\ndefects. Possible structures of such defects are discussed.",
        "positive": "Magnetization Dissipation in the Ferromagnetic Semiconductor (Ga,Mn)As: We compute the Gilbert damping in (Ga,Mn)As based on the scattering theory of\nmagnetization relaxation. The disorder scattering is included\nnon-perturbatively. In the clean limit, the spin-pumping from the localized\nd-electrons to the itinerant holes dominates the relaxation processes. In the\ndiffusive regime, the breathing Fermi-surface effect is balanced by the effects\nof interband scattering, which cause the Gilbert damping constant to saturate\nat around 0.005. In small samples, the system shape induces a large anisotropy\nin the Gilbert damping."
    },
    {
        "anchor": "A New Approach to the Synthesis of Conjugated Polymer: Nanocrystal\n  Composites for Heterojunction Optoelectronics: We report a simple one pot process for the preparation of lead sulphide (PbS)\nnanocrystals in the conjugated polymer MEH-PPV, and we demonstrate electronic\ncoupling between the two components.",
        "positive": "Phase-field Crystals with Elastic Interactions: We report on a novel extension of the recent phase-field crystal (PFC) method\nintroduced in [Elder et al., Phys. Rev. Lett., Vol. 88, 245701:1-4 (2002)],\nwhich incorporates elastic interactions as well as crystal plasticity and\ndiffusive dynamics. In our model, elastic interactions are mediated through\nwave modes that propagate on time scales many orders of magnitude slower than\natomic vibrations but still much faster than diffusive times scales. This\nallows us to preserve the quintessential advantage of the PFC model: the\nability to simulate atomic-scale interactions and dynamics on time scales many\norders of magnitude longer than characteristic vibrational time scales. We\ndemonstrate the two different modes of propagation in our model and show that\nsimulations of grain growth and elasto-plastic deformation are consistent with\nthe microstructural properties of nanocrystals."
    },
    {
        "anchor": "A Coherent Physics Picture of Topological Insulators at Single-Particle\n  Level: The study of topological property of band insulators is an interesting branch\nof condensed matter physics. Two types of topologically nontrivial insulators\nhave been extensively studied. The first type is characterized by a nonzero\nTKNN invariant or Chern number[1] which is directly related to the quantization\nof Hall conductance in the integer quantum Hall effect. Haledane propose a\nmodel with this type of band structure even in the absence of a macroscopic\nmagnetic field[2]. We refer to such materials \"Chern insulator\". The second\ntype called \"Z2 topological insulators\" is proposed recently[3, 4]. Quantum\nspin Hall effect has been predicted and observed in such systems.[5, 6].\nDespite the recent intensively study there are still some fundamental problems\nthat aren't quite clear about Z2 insulators even at the single-particle level.\nFor example, it's claimed that Z2 insulators will return to its origin state\nafter two cycles, thus coupling to the reservoirs is important for the Z2\ninsulators to continuously pump spin[7]. Theoretical and experimental results\nshow quantum spin Hall effect is an edge state transport property of the\nmaterials and coupling to the reservoir seems not play an important role. So\nthe Z2 picture is not satisfactory in explaining these phenomena. We study the\nrelationship of the ground states of Z2 insulators and that of Chern insulator.\nCombined with the results of recent researches on polarization of Chern\ninsulators[8] and topology of edge states[9] we propose a coherent physics\npicture of topological insulators.",
        "positive": "Vortex Ferroelectric Domains, Large-loop Weak Ferromagnetic Domains, and\n  Their Decoupling in Hexagonal (Lu, Sc)FeO3: The direct domain coupling of spontaneous ferroelectric polarization and net\nmagnetic moment can result in giant magnetoelectric (ME) coupling, which is\nessential to achieve mutual control and practical applications of\nmultiferroics. Recently, the possible bulk domain coupling, the mutual control\nof ferroelectricity (FE) and weak ferromagnetism (WFM) have been theoretically\npredicted in hexagonal LuFeO3. Here, we report the first successful growth of\nhighly-cleavable Sc-stabilized hexagonal Lu0.6Sc0.4FeO3 (h-LSFO) single\ncrystals, as well as the first visualization of their intrinsic cloverleaf\npattern of vortex FE domains and large-loop WFM domains. The vortex FE domains\nare on the order of 0.1-1 {\\mu}m in size. On the other hand, the loop WFM\ndomains are ~100 {\\mu}m in size, and there exists no interlocking of FE and WFM\ndomain walls. These strongly manifest the decoupling between FE and WFM in\nh-LSFO. The domain decoupling can be explained as the consequence of the\nstructure-mediated coupling between polarization and dominant in-plane\nantiferromagnetic spins according to the theoretical prediction, which reveals\nintriguing interplays between FE, WFM, and antiferromagnetic orders in h-LSFO.\nOur results also indicate that the magnetic topological charge tends to be\nidentical to the structural topological charge. This could provide new insights\ninto the induction of direct coupling between magnetism and ferroelectricity\nmediated by structural distortions, which will be useful for the future\napplications of multiferroics."
    },
    {
        "anchor": "The Electromigration Force in Metallic Bulk: The voltage induced driving force on a migrating atom in a metallic system is\ndiscussed in the perspective of the Hellmann-Feynman force concept, local\nscreening concepts and the linear-response approach. Since the force operator\nis well defined in quantum mechanics it appears to be only confusing to refer\nto the Hellmann-Feynman theorem in the context of electromigration. Local\nscreening concepts are shown to be mainly of historical value. The physics\ninvolved is completely represented in ab initio local density treatments of\ndilute alloys and the implementation does not require additional precautions\nabout screening, being typical for jellium treatments. The linear-response\napproach is shown to be a reliable guide in deciding about the two\ncontributions to the driving force, the direct force and the wind force.\nResults are given for the wind valence for electromigration in a number of FCC\nand BCC metals, calculated using an {\\it ab initio} KKR-Green's function\ndescription of a dilute alloy.",
        "positive": "Electron energy loss spectroscopy database synthesis and automation of\n  core-loss edge recognition by deep-learning neural networks: The ionization edges encoded in the electron energy loss spectroscopy (EELS)\nspectra enable advanced material analysis including composition analyses and\nelemental quantifications. The development of the parallel EELS instrument and\nfast, sensitive detectors have greatly improved the acquisition speed of EELS\nspectra. However, the traditional way of core-loss edge recognition is\nexperience based and human labor dependent, which limits the processing speed.\nSo far, the low signal-noise ratio and the low jump ratio of the core-loss\nedges on the raw EELS spectra have been challenging for the automation of edge\nrecognition. In this work, a convolutional-bidirectional long short-term memory\nneural network (CNN-BiLSTM) is proposed to automate the detection and elemental\nidentification of core-loss edges from raw spectra. An EELS spectral database\nis synthesized by using our forward model to assist in the training and\nvalidation of the neural network. To make the synthesized spectra resemble the\nreal spectra, we collected a large library of experimentally acquired EELS core\nedges. In synthesize the training library, the edges are modeled by fitting the\nmulti-gaussian model to the real edges from experiments, and the noise and\ninstrumental imperfectness are simulated and added. The well-trained CNN-BiLSTM\nnetwork is tested against both the simulated spectra and real spectra collected\nfrom experiments. The high accuracy of the network, 94.9 %, proves that,\nwithout complicated preprocessing of the raw spectra, the proposed CNN-BiLSTM\nnetwork achieves the automation of core-loss edge recognition for EELS spectra\nwith high accuracy."
    },
    {
        "anchor": "Twisted bilayer graphene fabricated by direct bonding in a high vacuum: Twisted bilayer graphene (TBG), in which two monolayer graphene are stacked\nwith an in-plane rotation angle, has recently become a hot topic due to unique\nelectronic structures. TBG is normally produced in air by the tear-and-stack\nmethod of mechanical exfoliation and transferring graphene flakes, by which a\nsizable, millimeter-order area, and importantly clean interface between layers\nare hard to obtain. In this study, we resolved these problems by directly\ntransferring the easy-to-exfoliate CVD-grown graphene on SiC substrate to\ngraphene in a high vacuum without using any transfer assisting medium and\nobserved electronic band modulations due to the strong interlayer coupling.",
        "positive": "Pervasive beyond room-temperature ferromagnetism in a doped van der\n  Waals magnet: Ni doped Fe$_5$GeTe$_2$ with $T_{\\text{C}}$ up to 478 K: The existence of long range magnetic order in low dimensional magnetic\nsystems, such as the quasi-two-dimensional (2D) van der Waals (vdW) magnets,\nhas attracted intensive studies of new physical phenomena. The vdW\nFe$_N$GeTe$_2$ ($N$ = 3, 4, 5; FGT) family is exceptional owing to its vast\ntunability of magnetic properties. Particularly, a ferromagnetic ordering\ntemperature ($T_{\\text{C}}$) above room temperature at $N$ = 5 (F5GT) is\nobserved. Here, our study shows that, by nickel (Ni) substitution of iron (Fe)\nin F5GT, a record high $T_{\\text{C}}$ = 478(6) K is achieved. Importantly,\npervasive, beyond-room-temperature ferromagnetism exists in almost the entire\ndoping range of the phase diagram of Ni-F5GT. We argue that this striking\nobservation in Ni-F5GT can be possibly due to several contributing factors, in\nwhich the structural alteration enhanced 3D magnetic couplings might be\ncritical for enhancing the ferromagnetic order."
    },
    {
        "anchor": "Unconventional Charge-density-wave Order in a Dilute d-band\n  Semiconductor: Electron-lattice coupling effects in low dimensional materials give rise to\ncharge density wave (CDW) order and phase transitions. These phenomena are\ncritical ingredients for superconductivity and predominantly occur in metallic\nmodel systems such as doped cuprates, transition metal dichalcogenides, and\nmore recently, in Kagome lattice materials. However, CDW in semiconducting\nsystems, specifically at the limit of low carrier concentration region, is\nuncommon. Here, we combine electrical transport, synchrotron X-ray diffraction\nand optical spectroscopy to discover CDW order in a quasi-one-dimensional (1D),\ndilute d-band semiconductor, BaTiS3, which suggests the existence of strong\nelectron-phonon coupling. The CDW state further undergoes an unusual transition\nfeaturing a sharp increase in carrier mobility. Our work establishes BaTiS3 as\na unique platform to study the CDW physics in the dilute filling limit to\nexplore novel electronic phases.",
        "positive": "The origin of phase separation in binary aluminosilicate glasses: The quest for hard and tough transparent oxide glasses is at the core of\nglass science and technology. Aluminosilicate glasses exhibiting nanoscale\nphase separation emerge as promising candidates for such materials.\nNevertheless, proper control of the phase separation represents a daunting\nchallenge due to its elusive origins. Here we employ large-scale molecular\ndynamics simulations and structural analysis to unravel the underlying\nmechanisms of the phase separation in aluminosilicate. The observed phase\nseparation originates from an arrangement of SiO$_4$ and AlO$_n$ polyhedra,\nwhich manifests from the second coordination shell and extends to higher\nshells. This specific arrangement is driven by repulsion between the polyhedra,\nreaching its maximum at around 50 mol% of Al$_2$O$_3$. This behavior becomes\npronounced around and below the glass transition temperature. This work sheds\nlight on the origin of phase separation and provides a route for further\nexploration across other compositions to develop glasses with adapted\nmechanical performance."
    },
    {
        "anchor": "Optical characterization of a-Si:H thin films grown by Hg-Photo-CVD: This submission is a duplicate of cond-mat/0608646.",
        "positive": "First-principles Study of Carrier Mobility in MX (M=Sn, Pb; X=P, As)\n  Monolayers: Compounds from groups IV and V have been the focus of recent research due to\ntheir impressive physical characteristics and structural stability. In this\nstudy, the MX monolayers (M=Sn, Pb; N=P, As) are investigated with\nfirst-principles calculations based on Boltzmann transport theory. The results\nshow that SnP, SnAs, and PbAs all exhibit indirect band gaps, whereas PbP is\nthe only semiconductor with a direct band gap. One important finding is that\nintravalley scattering has a significant impact on electron-phonon coupling.\nInterestingly, changes in carrier concentration do not affect the electron\nmobility within these MX monolayers, with SnP exhibiting the highest electron\nmobility among them. Subsequently, the SnP under a 6% biaxial strain is further\nexplored and the results demonstrated a considerable increase in electron\nmobility to 2,511.9 cm^2/Vs, which is attributable to decreased scattering.\nThis suggests that MX monolayers, especially SnP, are promising options for 2D\nsemiconductor materials in the future."
    },
    {
        "anchor": "Giant Rashba splitting of quasi-1D surface states on\n  Bi/InAs(110)-(2$\\times$1): Electronic states on the Bi/InAs(110)-(2$\\times$1) surface and its\nspin-polarized structure are revealed by angle-resolved photoelectron\nspectroscopy (ARPES), spin-resolved ARPES, and density-functional-theory\ncalculation. The surface state showed quasi-one-dimensional (Q1D) dispersion\nand a nearly metallic character; the top of the hole-like surface band is just\nbelow the Fermi level. The size of the Rashba parameter ($\\alpha_{\\rm R}$)\nreached quite a large value ($\\sim$5.5 eV\\AA). The present result would provide\na fertile playground for further studies of the exotic electronic phenomena in\n1D or Q1D systems with the spin-split electronic states as well as for advanced\nspintronic devices.",
        "positive": "Clustering in a precipitate free GeMn magnetic semiconductor: We present the first study relating structural parameters of precipitate free\nGe0.95Mn0.05 films to magnetisation data. Nanometer sized clusters - areas with\nincreased Mn content on substitutional lattice sites compared to the host\nmatrix - are detected in transmission electron microscopy (TEM) analysis. The\nfilms show no overall spontaneous magnetisation at all down to 2K. The TEM and\nmagnetisation results are interpreted in terms of an assembly of\nsuperparamagnetic moments developing in the dense distribution of clusters.\nEach cluster individually turns ferromagnetic below an ordering temperature\nwhich depends on its volume and Mn content."
    },
    {
        "anchor": "Scaling law for crystal nucleation time in glasses: Due to high viscosity, glassy systems evolve slowly to the ordered state.\nResults of molecular dynamics simulation reveal that the structural ordering in\nglasses becomes observable over \"experimental\" (finite) time-scale for the\nrange of phase diagram with high values of pressure. We show that the\nstructural ordering in glasses at such conditions is initiated through the\nnucleation mechanism, and the mechanism spreads to the states at extremely deep\nlevels of supercooling. We find that the scaled values of the nucleation time,\n$\\tau_1$ (average waiting time of the first nucleus with the critical size), in\nglassy systems as a function of the reduced temperature, $\\widetilde{T}$, are\ncollapsed onto a single line reproducible by the power-law dependence. This\nscaling is supported by the simulation results for the model glassy systems for\na wide range of temperatures as well as by the experimental data for the\nstoichiometric glasses at the temperatures near the glass transition.",
        "positive": "Voltage control of magnetic anisotropy in epitaxial Ru/Co2FeAl/MgO\n  heterostructures: Voltage control of magnetic anisotropy (VCMA) in magnetic heterostructures is\na key technology for achieving energy-efficiency electronic devices with\nultralow power consumption. Here, we report the first demonstration of the VCMA\neffect in novel epitaxial Ru/Co2FeAl(CFA)/MgO heterostructures with interfacial\nperpendicular magnetic anisotropy (PMA). Perpendicularly magnetized tunnel\njunctions with the structure of Ru/CFA/MgO were fabricated and exhibited an\neffective voltage control on switching fields for the CFA free layer. A large\nVCMA coefficient of 108 (139) fJ/Vm for the CFA film was achieved at room\ntemperature (4 K). The interfacial stability in the heterostructure was\nconfirmed by repeating measurements. Temperature dependences of both the\ninterfacial PMA and the VCMA effect were also investigated. It is found that\nthe temperature dependences follow power laws of the saturation magnetization\nwith an exponent of ~2. The significant VCMA effect observed in this work\nindicates that the Ru/CFA/MgO heterostructure could be one of the promising\ncandidates for spintronic devices with voltage control."
    },
    {
        "anchor": "Dislocation structure and mobility in the layered semiconductor InSe: A\n  first-principles study: The structure and mobility of dislocations in the layered semiconductor InSe\nis studied within a multiscale approach based on generalized Peierls--Nabarro\nmodel with material-specific parametrization derived from first principles. The\nplasticity of InSe turns out to be attributed to peculiarities of the\ngeneralized stacking fault relief for the interlayer dislocation slips such as\nexistence of the stacking fault with a very low energy and low energy barriers.\nOur results give a consistent microscopic explanation of recently observed\n[Science {\\bf 369}, 542 (2020)] exceptional plasticity of InSe.",
        "positive": "Thermal Analysis and Phase Diagram of the LiF-BiF3 System: Differential thermal analysis up to complete melting was performed for the\ncomplete pseudobinary system LiF-BiF3. Melts with high bismuth fluoride\nconcentration show severe evaporation, nevertheless even pure BiF3 could be\nmolten at 655 deg. C. The system contains one intermediate compound BiLiF4\nwhich melts by peritectic decomposition under the formation of LiF at 415 deg.\nC. The eutectic between BiLiF4 and BiF3 melts at 415 deg. C. By thermodynamic\nassessment the following parameters were found for BiLiF4: \\Delta H=-1514900\nJ/mol, S=158.5 J/mol K, c_p=166.173 -0.01072 T (in J/mol K). The melt has\nnegative excess Gibbs free energy."
    },
    {
        "anchor": "Microscopic Treatment of Solute Trapping and Drag: The long wavelength limit of a recent microscopic phase field crystal (PFC)\ntheory of a binary alloy mix- ture is used to derive an analytical\napproximation for the segregation coefficient as a function of the interface\nvelocity, and relate it to the two-point correlation function of the liquid and\nthe thermodynamic properties of solid and liquid phases. Our results offer the\nfirst analytic derivation of solute segregation and solute drag de- rived from\na microscopic model, and analytically support recent molecular dynamics and\nfully numerical PFC simulations. Our analytical result also provides an\nindependent framework, motivated from classical density functional theory, from\nwhich to elucidate the fundamental nature of solute drag, which is still highly\ncontested in the literature.",
        "positive": "Magnetic Instabilities and Phase Diagram of the Double-Exchange Model in\n  Infinite Dimensions: Dynamical mean-field theory is used to study the magnetic instabilities and\nphase diagram of the double-exchange (DE) model with Hund's coupling J_H >0 in\ninfinite dimensions. In addition to ferromagnetic (FM) and antiferromagnetic\n(AF) phases, the DE model supports a broad class of short-range ordered (SRO)\nstates with extensive entropy and short-range magnetic order. For any site on\nthe Bethe lattice, the correlation parameter q of a SRO state is given by the\naverage q=<sin^2(theta_i/2)>, where theta_i is the angle between any spin and\nits neighbors. Unlike the FM (q=0) and AF (q=1) transitions, the transition\ntemperature of a SRO state (T_{SRO}) with 0<q<1 cannot be obtained from the\nmagnetic susceptibility. But a solution of the coupled Green's functions in the\nweak-coupling limit indicates that a SRO state always has a higher transition\ntemperature than the AF for all fillings p<1 and even than the FM for 0.26\\le p\n\\le 0.39. For 0.39<p<0.73, where both the FM and AF phases are unstable for\nsmall J_H, a SRO phase has a non-zero T_{SRO} except close to p=0.5. As J_H\nincreases, T_{SRO} eventually vanishes and the FM dominates. For small J_H, the\nT=0 phase diagram is greatly simplified by the presence of the SRO phase. A SRO\nphase is found to have lower energy than either the FM or AF phases for 0.26\\le\np<1. Phase separation (PS) disappears as J_H-->0 but appears for J_H\\neq 0. For\np near 1, PS occurs between an AF with p=1 and either a SRO or a FM phase. The\nstability of a SRO state at T=0 can be understood by examining the interacting\nDOS,which is gapped for any nonzero J_H in an AF but only when J_H exceeds a\ncritical value in a SRO state."
    },
    {
        "anchor": "Rate-and-State Theory of Plastic Deformation Near a Circular Hole: We show that a simple rate-and-state theory accounts for most features of\nboth time-independent and time-dependent plasticity in a spatially\ninhomogeneous situation, specifically, a circular hole in a large stressed\nplate. Those features include linear viscoelastic flow at small applied\nstresses, strain hardening at larger stresses, and a dynamic transition to\nviscoplasticity at a yield stress. In the static limit, this theory predicts\nthe existence of a plastic zone near the hole for some but not all ranges of\nparameters. The rate-and-state theory also predicts dynamic failure modes that\nwe believe may be relevant to fracture mechanics.",
        "positive": "Are LLMs Ready for Real-World Materials Discovery?: Large Language Models (LLMs) create exciting possibilities for powerful\nlanguage processing tools to accelerate research in materials science. While\nLLMs have great potential to accelerate materials understanding and discovery,\nthey currently fall short in being practical materials science tools. In this\nposition paper, we show relevant failure cases of LLMs in materials science\nthat reveal current limitations of LLMs related to comprehending and reasoning\nover complex, interconnected materials science knowledge. Given those\nshortcomings, we outline a framework for developing Materials Science LLMs\n(MatSci-LLMs) that are grounded in materials science knowledge and hypothesis\ngeneration followed by hypothesis testing. The path to attaining performant\nMatSci-LLMs rests in large part on building high-quality, multi-modal datasets\nsourced from scientific literature where various information extraction\nchallenges persist. As such, we describe key materials science information\nextraction challenges which need to be overcome in order to build large-scale,\nmulti-modal datasets that capture valuable materials science knowledge.\nFinally, we outline a roadmap for applying future MatSci-LLMs for real-world\nmaterials discovery via: 1. Automated Knowledge Base Generation; 2. Automated\nIn-Silico Material Design; and 3. MatSci-LLM Integrated Self-Driving Materials\nLaboratories."
    },
    {
        "anchor": "Method for characterizing bulk recombination using photoinduced\n  absorption: The influence of reaction order and trap-assisted recombination on\ncontinuous-wave photoinduced absorption measurements is clarified through\nanalytical calculations and numerical simulations. The results reveal the\ncharacteristic influence of different trap distributions and enable\ndistinguishing between shallow exponential and Gaussian distributions as well\nas systems dominated by direct recombination by analyzing the temperature\ndependence of the in-phase and quadrature signals. The identifying features are\nthe intensity dependence of the in-phase at high intensity,\n$\\textit{PA}_\\text{I}\\propto I^{\\gamma_\\text{HI}}$, and the frequency\ndependence of the quadrature at low frequency, $\\textit{PA}_\\text{Q}\\propto\n\\omega^{\\gamma_\\text{LF}}$. For direct recombination $\\gamma_\\text{HI}$ and\n$\\gamma_\\text{LF}$ are temperature independent, for an exponential distribution\nthey depend on the characteristic energy $E_\\text{ch}$ as\n$\\gamma_\\text{HI}=1/(1+E_\\text{ch}/kT)$ and $\\gamma_\\text{LF}=kT/E_\\text{ch}$\nwhile a Gaussian distribution shows $\\gamma_\\text{HI}$ and $\\gamma_\\text{LF}$\nas functions of $I$ and $\\omega$, respectively.",
        "positive": "Effect of Exchange Interaction and Spin-Orbit Coupling on Spin Splitting\n  in CdSnX (X = S, Se and Te) nanoribbons: We have studied the topological properties of free standing Sn doped cadmium\nchalcogenide (CdSnX, X = S, Se and Te) nanoribbons of varying widths and three\ntypes of edges viz., distorted armchair, normal armchair and normal zigzag\nedges. The unsatisfied bonds of X and Sn atoms at the edges cause non-zero\nvalues of the magnetic moment. This introduces an exchange field leading to\ninverted band structure. The electronic band structures of distorted armchair\nedge nanoribbons also exhibit different types of spin splitting property for\ndifferent X atoms due to the different local orbital angular momentum at\nspecific X atomic site with the inclusion of spin orbit coupling (SOC). The gap\nopening at the band crossings near the Fermi level after inclusion of SOC are\nmainly due to SOC of Sn atom and are responsible for the electron and hole\npockets making the system topologically exotic. All the distorted edge\nnanoribbons show metallic behaviour with non-zero magnetic moments. Amongst CdX\n(X = S, Se and Te) nanoribbons, systems containing S atoms exhibit Weyl-like\nsemi-metallic behavior and not much change with width, that of Se atoms exhibit\nZeeman-type spin splitting and significant change with varying width, whereas\nsystems containing Te atoms show signature of Rashba spin splitting along with\nZeeman-type spin splitting and moderate change with varying width. The armchair\nedge nanoribbons show wide gap semiconducting behaviour. Zeeman-type spin\nsplitting is seen in the valence band region for systems containing S atoms and\nRashba spin splitting is visible in the conduction band region for systems\ncontaining Se and Te atoms. For zigzag edge nanoribbons, no such signature of\nspin splitting is observed although all the nanoribbons acquire very high\nmagnetic moments."
    },
    {
        "anchor": "Modelling electron-phonon interactions in graphene with curved space\n  hydrodynamics: We introduce a different perspective describing electron-phonon interactions\nin graphene based on curved space hydrodynamics. Interactions of phonons with\ncharge carriers increase the electrical resistivity of the material. Our\napproach captures the lattice vibrations as curvature changes in the space\nthrough which electrons move following hydrodynamic equations. In this picture,\ninertial corrections to the electronic flow arise naturally effectively\nproducing electron-phonon interactions. The strength of the interaction is\ncontrolled by a coupling constant, which is temperature independent. We apply\nthis model to graphene and recover satisfactorily the linear scaling law for\nthe resistivity that is expected at high temperatures. Our findings open up a\nnew perspective of treating electron-phonon interactions in graphene, and also\nin other materials where electrons can be described by the Fermi liquid theory.",
        "positive": "Unusual acceleration and size effects in grain boundary migration with\n  shear coupling: Grain boundary (GB) migration is widely believed to maintain a linear\nrelation between its displacement and time under a constant driving force. In\nthis study, we investigated the migration behaviors of a set of GBs in Ni by\napplying the synthetic driving force and shear stress via atomistic\nsimulations. It was found that the displacements of some shear-coupling GBs do\nnot exhibit a linear or approximately linear relation with the time, as widely\nassumed, but evidently exhibit an acceleration tendency. Moreover, the boundary\nvelocity significantly decreases when increasing the bicrystal size\nperpendicular to the GB plane. These behaviors were verified to be independent\nof the magnitude and type of driving force but closely related to the\ntemperature and revealed to be unique to shear-coupling GBs exhibiting a rise\nin the kinetic energy component along the shear direction. Moreover, after many\nattempts, we found that the acceleration in migration and size effect can be\nlargely alleviated by adopting one specific kind of boundary condition.\nNevertheless, the continuous rise of kinetic energy still exists and leads to\nthe true driving force for GB migration lower than the nominally applied value.\nFor that reason, a technique is proposed to extract the true driving force\nbased on a quantitative analysis of the work-energy relation in the bicrystal\nsystem. Accordingly, the calculated true mobility shows that the recently\nproposed mobility tensor may not be symmetric at relatively large driving\nforces."
    },
    {
        "anchor": "Electronic structure of shallow donor state associated with muonium in\n  rutile TiO$_2$: The hyperfine structure of the interstitial muonium (Mu) center in rutile\n(TiO$_2$, weakly $n$-type) has been identified by means of muon spin rotation\ntechnique. The angle-resolved hyperfine parameter has a tetragonal anisotropy\nwithin the $ab$ plane and axial anisotropy along the $c$ axis, strongly\nsuggesting that Mu simulates the known local structure of interstitial hydrogen\n(H) located at an off-center position within a channel along $c$ axis, and the\nelectron wave function bound to Mu is highly delocalized (~1.5 nm along $c$\naxis, ~0.8 nm for $a$ axis). The ionization energy of Mu ($\\rightarrow \\mu^+ +\ne^-$) due to thermal activation is deduced to be 1.2(4) meV, as is directly\ninferred from the disappearance of Mu signal above ~8 K. These observations\nsuggest that electronic level associated with Mu (as well as H) is situated\nnear the bottom of the conduction band, serving as a shallow donor state in\nrutile.",
        "positive": "Quantum ring models and action-angle variables: We suggest to use the action-angle variables for the study of properties of\n(quasi)particles in quantum rings. For this purpose we present the action-angle\nvariables for three two-dimensional singular oscillator systems. The first one\nis the usual (Euclidean) singular oscillator, which plays the role of the\nconfinement potential for the quantum ring. We also propose two singular\nspherical oscillator models for the role of the confinement system for the\nspherical ring. The first one is based on the standard Higgs oscillator\npotential. We show that, in spite of the presence of a hidden symmetry, it is\nnot convenient for the study of the system's behaviour in a magnetic field. The\nsecond model is based on the so-called CP(1) oscillator potential and respects\nthe inclusion of a constant magnetic field."
    },
    {
        "anchor": "The Winner Takes It All: Carbon Supersedes Hexagonal Boron Nitride with\n  Graphene on Transition Metals at High Temperatures: The production of high-quality hexagonal boron nitride (h-BN) is essential\nfor the ultimate performance of two-dimensional (2D) materials-based devices,\nsince it is the key 2D encapsulation material. Here, a decisive guideline is\nreported for fabricating high-quality h-BN on transition metals: It is crucial\nto exclude carbon from h-BN related process. Otherwise carbon prevails over\nboron and nitrogen due to its larger binding energy, thereupon forming graphene\non metals after high-temperature annealing. We demonstrate the surface\nreaction-assisted conversion from h-BN to graphene with high-temperature\ntreatments. The pyrolysis temperature Tp is an important quality indicator for\nh-BN/metals. When the temperature is lower than Tp, the quality of h-BN layer\nis improved upon annealing. While the annealing temperature is above Tp, in\ncase of carbon-free conditions, the h-BN disintegrates and nitrogen desorbs\nfrom the surface more easily than boron, eventually leading to clean metal\nsurfaces. However, once the h-BN layer is exposed to carbon, graphene forms on\nPt(111) in the high-temperature regime. This not only provides an indispensable\nprinciple (avoid carbon) for fabricating high-quality h-BN materials on\ntransition metals, but also offers a straightforward method for the surface\nreaction-assisted conversion from h-BN to graphene on Pt(111).",
        "positive": "Conduction Mechanisms in Epitaxial NiO/Graphene Gas Sensors: Integrated, highly sensitive and reversible sensor devices for toxic and\nhazardous gases in environmental pollution monitoring can be realized with\ngraphene-based materials. Here we show that, single layer graphene grown on SiC\ncan be utilized to implement sensor devices being extremely sensitive towards\nNO2 showing an n-type response. A second type of sensor with an added NiO layer\non top of the single layer graphene changed its response to p-type but did not\nreduce its sensitivity. We show that the conduction switch from n-type to\np-type was not a consequence of an alteration of the graphene layer but is\nfound to be an effect of the NiO layer. We find that the NiO leads to lowering\nof the Fermi level to a point that a crossing of the Dirac Point in the\ngraphene switched the conduction type. These sensors were tested in the 100 ppb\nNO2 regime, showing good response and a detection limit extrapolated to be\nbelow 1 ppb. This new NiO/graphene/SiC configuration can be an attractive\np-type sub-ppb sensor platform for NO2 and related gases."
    },
    {
        "anchor": "Formation of periodical metal oxide multilayer structures for the X-ray\n  standing wave applications: Periodical multilayer (ML) structures can be used as generators of X-ray\nstanding waves (XSW) for investigation of objects and processes on solid/liquid\nand solid/gas interfaces. In this paper, we investigate the specific\nrequirements to the structural properties of the multilayer structures for XSW\napplication. We consider the effect of typical defects in the ML structure on\nthe X-ray standing wave formation and show that the X-ray standing wave is very\nrobust against the random imperfection in the multilayer structure. In\ncontrast, the roughness of the topmost layer will have a strong influence on\nthe XSW experimental results, as the ML serves as a support for the\ninvestigated objects, so that the surface geometry gets directly translated\ninto the objects. In the experimental part of this work, we have used the\nion-beam deposition to grow Ni/Al metal- and metal oxide-based multilayers and\ninvestigate with AFM their surface quality. The presented results demonstrate\nthat metal oxides can be successfully used as basic material for X-ray\nmultilayer standing wave generators.",
        "positive": "Evolutionary search for new high-k dielectric materials: methodology and\n  applications to hafnia-based oxides: High-k dielectric materials are important as gate oxides in microelectronics\nand as potential dielectrics for capacitors. In order to enable computational\ndiscovery of novel high-k dielectric materials, we propose a fitness model\n(energy storage density) that includes the dielectric constant, bandgap, and\nintrinsic breakdown field. This model, used as fitness function in conjunction\nwith first-principles calculations and global optimization evolutionary\nalgorithm USPEX, efficiently leads to practically important results. We found a\nnumber of high-fitness structures of SiO2 and HfO2, some of which correspond to\nknown phases and some are new. The results allow us to propose characteristics\n(genes) common to high-fitness structures - these are the coordination\npolyhedra and their degree of distortion. Our variable-composition searches in\nthe HfO2-SiO2 system uncovered several high-fitness states. This hybrid\nalgorithm opens up a new avenue of discovering novel high-k dielectrics with\nboth fixed and variable compositions, and will speed up the process of\nmaterials discovery."
    },
    {
        "anchor": "Commensurate and incommensurate magnetic order in spin-1 chains stacked\n  on the triangular lattice in Li$_2$NiW$_2$O$_8$: We report thermodynamic properties, magnetic ground state, and microscopic\nmagnetic model of the spin-1 frustrated antiferromaget Li$_{2}$NiW$_{2}$O$_{8}$\nshowing successive transitions at $T_{\\rm N1}\\simeq 18$ K and $T_{\\rm N2}\\simeq\n12.5$ K in zero field. Nuclear magnetic resonance and neutron diffraction\nreveal collinear and commensurate magnetic order with the propagation vector\n$\\mathbf k=(\\frac12,0,\\frac12)$ below $T_{\\rm N2}$. The ordered moment of 1.8\n$\\mu_B$ at 1.5 K is directed along $[0.89(9),-0.10(5),-0.49(6)]$ and matches\nthe magnetic easy axis of spin-1 Ni$^{2+}$ ions, which is determined by the\nscissor-like distortion of the NiO$_6$ octahedra. Incommensurate magnetic\norder, presumably of spin-density-wave type, is observed in the region between\n$T_{\\rm N2}$ and $T_{\\rm N1}$. Density-functional band-structure calculations\nput forward a three-dimensional spin lattice with spin-1 chains running along\nthe $[01\\bar 1]$ direction and stacked on a spatially anisotropic triangular\nlattice in the $ab$ plane. We show that the collinear magnetic order in\nLi$_2$NiW$_2$O$_8$ is incompatible with the triangular lattice geometry and\nthus driven by a pronounced easy-axis single-ion anisotropy of Ni$^{2+}$.",
        "positive": "Controlling ferroelectric hysteresis offsets in PbTiO$_{3}$ based\n  superlattices: Ferroelectric materials are characterized by degenerate ground states with\nmultiple polarization directions. In a ferroelectric capacitor this should\nmanifest as equally favourable up and down polarization states. However, this\nideal behavior is rarely observed in ferroelectric thin films and superlattice\ndevices, which generally exhibit a built-in bias which favors one polarization\nstate over the other. Often this polarization asymmetry can be attributed to\nthe electrodes. In this study we examine bias in PbTiO$_3$-based ferroelectric\nsuperlattices that is not due to the electrodes, but rather to the nature of\nthe defects that form at the interfaces during growth. Using a combination of\nexperiments and first-principles simulations, we are able to explain the sign\nof the observed built-in bias and its evolution with composition. Our insights\nallow us to design devices with zero built-in bias by controlling the\ncomposition and periodicity of the superlattices."
    },
    {
        "anchor": "Combined Fast Reversible Liquid-like Elastic Deformation with\n  Topological Phase Transition in Na$_3$Bi: By means of first-principles calculations, we identified the structural phase\ntransition of Na$_3$Bi from hexagonal ground state to cubic $cF$16 phase above\n0.8 GPa, in agreement with the experimental findings. Upon the releasing of\npressure, \\emph{cF}16 phase of Na$_3$Bi is mechanically stable at ambient\ncondition. The calculations revealed that the $cF$16 phase is topological\nsemimetal, in similarity to well-known HgTe and it even exhibits an unusually\nlow $C^\\prime$ modulus (only about 1.9 GPa) and a huge anisotropy, $A^u$ of as\nhigh as 11, the third highest value among all known cubic crystals in their\nelastic behaviors. These facts render \\emph{cF}16-type Na$_3$Bi very soft with\na liquid-like elastic deformation in the (110)$<$1$\\overline{1}$0$>$ slip\nsystem. Importantly, as accompanied with this deformation, Na$_3$Bi shows a\ntopological phase transition from a topological semimetal state at its\nstrain-free cubic phase to a topological insulating state at its distorted\nphase. Because the $C^\\prime$ elastic deformation almost costs no energy in a\nreversible and liquid-like soft manner, \\emph{cF}16-type Na$_3$Bi would\npotentially provide a fast on/off switching way between topological insulator\nand topological semimetal, which would be beneficial to the quantum electronic\ndevices for practical applications.",
        "positive": "Combining phonon accuracy with high transferability in Gaussian\n  approximation potential models: Machine learning driven interatomic potentials, including Gaussian\napproximation potential (GAP) models, are emerging tools for atomistic\nsimulations. Here, we address the methodological question of how one can fit\nGAP models that accurately predict vibrational properties in specific regions\nof configuration space, whilst retaining flexibility and transferability to\nothers. We use an adaptive regularization of the GAP fit that scales with the\nabsolute force magnitude on any given atom, thereby exploring the Bayesian\ninterpretation of GAP regularization as an \"expected error\", and its impact on\nthe prediction of physical properties for a material of interest. The approach\nenables excellent predictions of phonon modes (to within 0.1-0.2 THz) for\nstructurally diverse silicon allotropes, and it can be coupled with existing\nfitting databases for high transferability. These findings and workflows are\nexpected to be useful for GAP-driven materials modeling more generally."
    },
    {
        "anchor": "Degenerate skyrmionic states in synthetic antiferromagnets: Topological magnetic textures, characterized by integer topological charge\n$S$, are potential candidates in future magnetic logic and memory devices, due\nto their smaller size and expected low threshold current density for their\nmotion. An essential requirement to stabilize them is the Dzyaloshinskii-Moriya\ninteraction (DMI) which promotes a particular chirality, leading to a unique\nvalue of $S$ in a given material. However, recently coexistence of skyrmions\nand antiskyrmions, with opposite topological charge, in frustrated ferromagnets\nhas been predicted using $J_1$--$J_2$--$J_3$ classical Heisenberg model, which\nopens new perspectives, to use the topological charge as an additional degree\nof freedom. In this work, we propose another approach of using a synthetic\nantiferromagnetic (SAF) system, where one of the ferromagnetic (FM) layer has\nisotropic and the other FM layer has anisotropic DMI to promote the existence\nof skyrmions and antiskyrmions, respectively. A frustrated interaction arises\ndue to the coupling between the magnetic textures in the FM layers, which\nenables the stabilization and coexistence of 6 novel elliptical topological\ntextures.",
        "positive": "Role of occupied d bands in the dynamics of excited electrons and holes\n  in Ag: The role that occupied $d$ bands play in the inelastic lifetime of bulk and\nsurface states in Ag is investigated from the knowledge of the quasiparticle\nself-energy. In the case of bulk electrons, $sp$ bands are taken to be\nfree-electron like. For surface states, the surface band structure of $sp$\nstates is described with the use of a realistic one-dimensional hamiltonian.\nThe presence of occupied $d$ states is considered in both cases by introducing\na polarizable background. We obtain inelastic lifetimes of bulk electrons that\nare in good agreement with first-principles band-structure calculations. Our\nsurface-state lifetime calculations indicate that the agreement with measured\nlifetimes of both crystal-induced and image-potential induced surface states on\nAg(100) and Ag(111) is considerably improved when the screening of $d$\nelectrons is taken into account."
    },
    {
        "anchor": "Structure and relaxor ferroelectric behavior of novel tungsten bronze\n  type ceramic, Sr5BiTi3Nb7O30: A novel lead-free tungsten bronze type ceramic Sr5BiTi3Nb7O30, was prepared\nby a conventional solid-state reaction route. The room-temperature crystal\nstructure shows an average structure with centro-symmetric space group P4/mbm\nidentified by synchrotron XRD. Temperature dependence of dielectric\npermittivity indicates that Sr5BiTi3Nb7O30 is a ferroelectric relaxor with Tm\nnear 260 K. The ceramic displays stronger frequency dispersion and lower\nphase-transition temperature compared with Sr6Ti2Nb8O30. A macroscopic and\nphenomenological statistical model was employed to describe the temperature\ndependence of their dielectric responses. The calculated size of polar\nnanoregions (PNRs) of Sr5BiTi3Nb7O30 compared with Sr6Ti2Nb8O30 implies that\nthe stronger diffusion phase transition for the former is related to the\ndisorder emerged in both A and B sites. The smaller PNRs can be activated at\nlower temperature but have smaller electrical dipole moment. This is the origin\nof relaxor behavior of Sr5BiTi3Nb7O30 with lower Tm and dielectric\npermittivity. The PNRs is related to a local structure with a polar space group\nP4bm, which contributes to the dielectric frequency dispersion of relaxor\nbehavior. This work opens up a promising feasible route to the development of\nrelaxor ferroelectrics in tungsten bronze type oxides.",
        "positive": "Metastable structure of photoexcited WO$_{3}$ determined by the\n  pump--probe extended X-ray absorption fine structure spectroscopy and\n  constrained thorough search analysis: We have determined the local structure of photoexcited metastable WO$_3$\ncreated 150 ps after 400 nm laser irradiation by the pulse pump--probe\nL$_3$-edge extended X-ray absorption fine structure spectroscopy and the\nconstrained thorough search analysis. We have found a highly distorted\noctahedral local structure with one of the shortest W=O bonds being further\nshortened to 1.66 \\AA while the other five bonds were elongated even though\ntheoretical calculations predicted the reverse change. We discuss this\ncontradiction and propose a possible structure for the metastable state."
    },
    {
        "anchor": "Solvent-dependent termination, size and stability in polyynes synthesis\n  by laser ablation in liquids: In recent years there has been a growing interest in sp-carbon chains as\npossible novel nanostructures. An example of sp-carbon chains are the so-called\npolyynes, characterized by the alternation of single and triple bonds that can\nbe synthesized by pulsed laser ablation in liquid (PLAL) of a graphite target.\nIn this work, by exploiting different solvents in the PLAL process, e.g. water,\nacetonitrile, methanol, ethanol, and isopropanol, we systematically investigate\nthe solvent role in polyyne formation and stability. The presence of methyland\ncyano-groups in the solutions influences the termination of polyynes, allowing\nto detect, in addition to hydrogen-capped polyynes up to HC22H, methyl-capped\npolyynes up to 18 carbon atoms (i.e. HCnCH3) and cyanopolyynes up to HC12CN.\nThe assignment of each species was done by UV-Vis spectroscopy and supported by\ndensity functional theory simulations of vibronic spectra. In addition,\nsurface-enhanced Raman spectroscopy allowed to observe differences, due to\ndifferent terminations (hydrogen, methyl-and cyano group), in the shape and\npositions of the characteristic Raman bands of the size-selected polyynes. The\nevolution in time of each polyyne has been investigated evaluating the\nchromatographic peak area, and the effect of size, terminations and solvents on\npolyynes stability has been individuated.",
        "positive": "Generative Design of inorganic compounds using deep diffusion language\n  models: Due to the vast chemical space, discovering materials with a specific\nfunction is challenging. Chemical formulas are obligated to conform to a set of\nexacting criteria such as charge neutrality, balanced electronegativity,\nsynthesizability, and mechanical stability. In response to this formidable\ntask, we introduce a deep learning-based generative model for material\ncomposition and structure design by learning and exploiting explicit and\nimplicit chemical knowledge. Our pipeline first uses deep diffusion language\nmodels as the generator of compositions and then applies a template-based\ncrystal structure prediction algorithm to predict their corresponding\nstructures, which is then followed by structure relaxation using a universal\ngraph neural network-based potential. The density functional theory (DFT)\ncalculations of the formation energies and energy-above-the-hull analysis are\nused to validate new structures generated through our pipeline. Based on the\nDFT calculation results, six new materials, including Ti2HfO5, TaNbP, YMoN2,\nTaReO4, HfTiO2, and HfMnO2, with formation energy less than zero have been\nfound. Remarkably, among these, four materials, namely Ti2$HfO5, TaNbP, YMoN2,\nand TaReO4, exhibit an e-above-hull energy of less than 0.3 eV. These findings\nhave proved the effectiveness of our approach."
    },
    {
        "anchor": "Nucleation of interfacial shear cracks in thin films on disordered\n  substrates: We formulate a theoretical model of the shear failure of a thin film tethered\nto a rigid substrate. The interface between film and substrate is modeled as a\ncohesive layer with randomly fluctuating shear strength/fracture energy. We\ndemonstrate that, on scales large compared with the film thickness, the\ninternal shear stresses acting on the interface can be approximated by a\nsecond-order gradient of the shear displacement across the interface. The model\nis used to study one-dimensional shear cracks, for which we evaluate the\nstress-dependent probability of nucleation of a critical crack. This is used to\ndetermine the interfacial shear strength as a function of film geometry and\nstatistical properties of the interface.",
        "positive": "The role of pressure-induced stacking faults on the magnetic properties\n  of gadolinium: Experimental data show that under pressure, Gd goes through a series of\nstructural transitions hcp to Sm-type (close-packed rhombohedral) to dhcp that\nis accompanied by a gradual decrease of the Curie temperature and magnetization\ntill the collapse of a finite magnetization close to the dhcp structure. We\nexplore theoretically the pressure-induced changes of the magnetic properties,\nby describing these structural transitions as the formation of fcc stackings\nfaults. Using this approach, we are able to describe correctly the variation of\nthe Curie temperature with pressure, in contrast to a static structural model\nusing the hcp structure."
    },
    {
        "anchor": "Predicting highly correlated hydride-ion diffusion in SrTiO$_3$ crystals\n  based on the fragment kinetic Monte Carlo method with machine-learning\n  potential: Oxyhydrides have drawn attention because of their fast ion conductivity and\nstrong reducing properties. Recently, hydride ion migration in\nSrTiO$_{3-x}$H$_{x}$ oxyhydride crystals has been investigated, showing that\nhydride ion migration is blocked by slow oxygen diffusion. In this study, we\ninvestigate the hydride-ion migration mechanism using a kinetic Monte Carlo\napproach to understanding the relationship between the hydride and oxygen ions.\nThe difficulties in applying the method to hydride and oxygen ion migration\ninvolve complex changes in the ionic migration barrier, which shifts\ndynamically depending on the characteristics of the surrounding hydride and\noxygen ions. We can predict these complex changes using a machine-learning\nneural network model. The simulation can then be performed using this model to\npredict the temperature-dependent ionic-migration behavior. We found that our\nsimulation results with respect to the activation barrier for hydride ion\ndiffusion accorded well with those obtained by experiment. We also found that\nhydride ion migration is affected by slow oxygen diffusion and that oxygen\ndiffusion is accelerated by changes in the ionic migration barriers. The\nparallel-processing efficiency of our proposed method was 84.92 \\% for our\n1,000-CPU implementation, suggesting that the approach should be widely\napplicable to simulations of ionic migration in crystals at a reasonable\ncomputational cost.",
        "positive": "Structural phase transition and its consequences on optical behavior of\n  LaV$_{1-x}$Nb$_x$O$_4$: We present the structural, electronic, vibrational, and photoluminescence\nproperties of polycrystalline LaV$_{1-x}$Nb$_x$O$_4$ ($x =$ 0--0.2) samples at\nroom temperature. The substitution of Nb at the V site shows the fascinating\nstructural and optical behavior due to their isoelectronic character and larger\nionic radii of Nb$^{5+}$ as compared to the V$^{5+}$. The Rietveld refinement\nof x-ray diffraction patterns demonstrate that the $x=$ 0 sample exist in a\nmonoclinic (P2$_1$/n) phase, whereas for the $x >$ 0, both monoclinic and\nscheelite-tetragonal (I4$_1$/a) phases co-exist in a certain proportion.\nInterestingly, a monotonous enhancement in the Raman spectral intensity with Nb\nsubstitution is correlated with the substitution induced increase in the\nscheelite-tetragonal phase. The x-ray absorption measurements reveal that the\nLa ions exist in a trivalent oxidation state, while V and Nb cations possess 5+\noxidation state in tetrahedral coordination. Moreover, the Fourier-transform\ninfrared (FTIR) spectra indicate that the Nb substitution give origin to some\nadditional IR modes owing to the deformation of the VO$_4$$^{3-}$ tetrahedra\nand mixing of monoclinic and tetragonal phases. The photoluminescence\nmeasurements on these samples exhibit broadband spectra and their deconvolution\ndesignate the availability of more than one electron-hole pairs recombination\ncenter."
    },
    {
        "anchor": "Ge-substitutional defects and the r3xr3 <--> 3x3 transition in\n  alpha--SnGe(111): The structure and energetics of Ge substitutional defects on the\nalpha-Sn/Ge(111) surface are analyzed using Density Functional Theory (DFT)\nmolecular dynamics (MD) simulations. An isolated Ge defect induces a very local\ndistortion of the 3x3 reconstruction, confined to a significant downwards\ndisplacement (-0.31 A) at the defect site and a modest upward displacement\n(0.05 A) of the three Sn nearest neighbours with partially occupied dangling\nbonds. Dynamical fluctuations between the two degenerate ground states yield\nthe six-fold symmetry observed around a defect in the experiments at room\ntemperature. Defect-defect interactions are controlled by the energetics of the\ndeformation of the 3x3 structure: They are negligible for defects on the\nhoneycomb lattice and quite large for a third defect on the hexagonal lattice,\nexplaining the low temperature defect ordering.",
        "positive": "Ultratransparent glass-ceramics: the structure factor and the quenching\n  of the Rayleigh scattering: Glass-ceramics with nanocrystals present a transparency higher than that\nexpected from the theory of Rayleigh scattering. This ultra-transparency is\nattributed to the spatial correlation of the nanoparticles. The structure\nfactor is calculated for a simple model system, the random sequential addition\nof equal spheres, at different volume filling factor. The spatial correlation\ngiven by the constraint that particles cannot superimpose produces a\ndiffraction peak with a low $S(q)$ in its low-$q$ tail, which is relevant for\nlight scattering. The physical mechanism producing high transparency in\nglass-ceramics is demonstrated to be the low density fluctuation in the number\nof scatterers."
    },
    {
        "anchor": "Comparing different approaches to model the atomic structure of a\n  ternary decagonal quasicrystal: It is shown that the covering approach with a single decagonal prototile can\nbe transformed into a hexagon, boat and star tiling. Particularly, the atomic\ndecoration recently proposed by Cockayne and Widom (Phys. Rev. Lett. 81, 598\n(1998)) as a structure model for the decagonal phase is investigated. There,\nconflicts with the prototile approach arise which are due to specific\npeculiarities of the decoration. The above model is compared with recent\nexperimental images which give strong support to its main features, but\ncontradict competing structure proposals. The implications for the\nstabilization mechanism are discussed.",
        "positive": "Effective electronic response of a system of metallic cylinders: The electronic response of a composite consisting of aligned metallic\ncylinders in vacuum is investigated, on the basis of photonic band structure\ncalculations. The effective long-wavelength dielectric response function is\ncomputed, as a function of the filling fraction. A spectral representation of\nthe effective response is considered, and the surface mode strengths and\npositions are analyzed. The range of validity of a Maxwell-Garnett-like\napproach is discussed, and the impact of our results on absorption spectra and\nelectron energy-loss phenomena is addressed."
    },
    {
        "anchor": "Stoner factors of doped 122 Fe-based superconductors: First principles\n  results: A comprehensive study on the evolution of Stoner factor with doping\nconcentration for various doped 122 systems (like BaFe$_2$As$_2$,\nSrFe$_2$As$_2$) of Fe-based superconductors is presented. Our first principles\nelectronic structure calculations reveal that for Co/Ru (electron or\niso-electronic) doping at Fe sites or P doping at As sites result in a\nreduction of Stoner factor with increasing doping concentration. On the\ncontrary, in case of Na/K (hole) doping at the Ba sites, Stoner factor is\nenhanced for higher doping concentrations. This may be considered as an\nindicator of elevation of \"magnetic fluctuation\" in these systems. We find that\nthe Stoner factor uniquely follows the variation of the pnictide height\nz$_{As}$/Fe-As bond length with various kinds of doping. Our calculated Fermi\nsurfaces explicate the diversities in the behaviour of Stoner factors for\nvarious doped 122 systems ; larger degree of Fermi surface nesting, larger the\nvalue of Stoner factor and vice versa.",
        "positive": "Origin of Mechanical and Dielectric Losses from Two-Level Systems in\n  Amorphous Silicon: Amorphous silicon contains tunneling two-level systems, which are the\ndominant energy loss mechanisms for amorphous solids at low temperatures. These\ntwo-level systems affect both mechanical and electromagnetic oscillators and\nare believed to produce thermal and electromagnetic noise and energy loss.\nHowever, it is unclear whether the two-level systems that dominate mechanical\nand dielectric losses are the same; the former relies on phonon-TLS coupling,\nwith an elastic field coupling constant, $\\gamma$, while the latter depends on\na TLS dipole moment, $p_0$, which couples to the electromagnetic field.\nMechanical and dielectric loss measurements as well as structural\ncharacterization were performed on amorphous silicon thin films grown by\nelectron beam deposition with a range of growth parameters. Samples grown at\n425 $^{\\circ}$C show a large reduction of mechanical loss (34 times) and a far\nsmaller reduction of dielectric loss (2.3 times) compared to those grown at\nroom temperature. Additionally, mechanical loss shows lower loss per unit\nvolume for thicker films, while dielectric loss shows lower loss per unit\nvolume for thinner films. Analysis of these results indicate that mechanical\nloss correlates with atomic density, while dielectric loss correlates with\ndangling bond density, suggesting a different origin for these two energy\ndissipation processes in amorphous silicon."
    },
    {
        "anchor": "Elastic and electronic properties of fluorite RuO_2 from first principle: The elastic, thermodynamic, and electronic properties of fluorite RuO_2 under\nhigh pressure are investigated by plane-wave pseudopotential density functional\ntheory. The optimized lattice parameters, elastic constants, bulk modulus, and\nshear modulus are consistent with other theoretical values. The phase\ntransition from modified fluorite-type to fluorite is 88 GPa (by localized\ndensity approximation, LDA) or 115.5 GPa (by generalized gradient\napproximation, GGA). The Young's modulus and Lam\\'e's coefficients are also\nstudied under high pressure. The structure turned out to be stable for the\npressure up to 120 GPa by calculating elastic constants. In addition, the\nthermodynamic properties, including the Debye temperature, heat capacity,\nthermal expansion coefficient, Gr\\\"uneisen parameter, and Poisson's ratio, are\ninvestigated. A small band gap is found in the electronic structure of fluorite\nRuO_2 and the bandwidth increases with the pressure. Also, the present\nmechanical and electronic properties demonstrate that the bonding nature is a\ncombination of covalent, ionic, and metallic contributions.",
        "positive": "First-principles study of electronic band structure and elastic\n  properties of superconducting nanolaminate Ti2InC: The full-potential linearized augmented plane wave method with the\ngeneralized gradient approximation for the exchange-correlation potential\n(FLAPW-GGA) is used to predict the electronic and elastic properties of the\nnewly discovered superconducting nanolaminate Ti2InC. The band structure,\ndensity of states and Fermi surface features are discussed. The optimized\nlattice parameters, independent elastic constants, bulk and shear moduli,\ncompressibility are evaluated and discussed. The elastic parameters of the\npolycrystalline Ti2InC ceramics are estimated numerically for the first time."
    },
    {
        "anchor": "Navigating at Will on the Water Phase Diagram: Despite the simplicity of its molecular unit, water is a challenging system\nbecause of its uniquely rich polymorphism and predicted but yet unconfirmed\nfeatures. Introducing a novel space of generalized coordinates that capture\nchanges in the topology of the interatomic network, we are able to\nsystematically track transitions among liquid, amorphous and crystalline forms\nthroughout the whole phase diagram of water, including the nucleation of\ncrystals above and below the melting point. Our approach, based on molecular\ndynamics and enhanced sampling / free energy calculation techniques, is not\nspecific to water and could be applied to very different structural phase\ntransitions, paving the way towards the prediction of kinetic routes connecting\npolymorphic structures in a range of materials.",
        "positive": "Measurement of the dynamical dipolar coupling in a pair of magnetic\n  nano-disks using a Ferromagnetic Resonance Force Microscope: We perform an extensive experimental spectroscopic study of the collective\nspin-wave dynamics occurring in a pair of magnetic nano-disks coupled by the\nmagneto-dipolar interaction. For this, we take advantage of the stray field\ngradient produced by the magnetic tip of a ferromagnetic resonance force\nmicroscope (f-MRFM) to continuously tune and detune the relative resonance\nfrequencies between two adjacent nano-objects. This reveals the anti-crossing\nand hybridization of the spin-wave modes in the pair of disks. At the exact\ntuning, the measured frequency splitting between the binding and anti-binding\nmodes precisely corresponds to the strength of the dynamical dipolar coupling\n$\\Omega$. This accurate f-MRFM determination of $\\Omega$ is measured as a\nfunction of the separation between the nano-disks. It agrees quantitatively\nwith calculations of the expected dynamical magneto-dipolar interaction in our\nsample."
    },
    {
        "anchor": "Reversible modifications of linear dispersion - graphene between boron\n  nitride monolayers: Electronic properties of the graphene layer sandwiched between two hexagonal\nboron nitride sheets have been studied using the first-principles calculations\nand the minimal tight-binding model. It is shown that for the ABC-stacked\nstructure in the absence of external field the bands are linear in the vicinity\nof the Dirac points as in the case of single-layer graphene. For certain atomic\nconfiguration, the electric field effect allows opening of a band gap of over\n230 meV. We believe that this mechanism of energy gap tuning could\nsignificantly improve the characteristics of graphene-based field-effect\ntransistors and pave the way for future electronic applications.",
        "positive": "Quantum dot self-assembly driven by a surfactant-induced morphological\n  instability: In strained heteroepitaxy, two-dimensional (2D) layers can exhibit a critical\nthickness at which three-dimensional (3D) islands self-assemble, relieving\nmisfit strain at the cost of an increased surface area. Here we show that such\na morphological phase transition can be induced on-demand using surfactants. We\nexplore Bi as a surfactant in the growth of InAs on GaAs(110), and find that\nthe presence of surface Bi induces Stranski-Krastanov growth of 3D islands,\nwhile growth without Bi always favors 2D layer formation. Exposing a static two\nmonolayer thick InAs layer to Bi rapidly transforms the layer into 3D islands.\nDensity functional theory calculations reveal that Bi reduces the energetic\ncost of 3D island formation by modifying surface energies. These 3D\nnanostructures behave as optically active quantum dots. This work illustrates\nhow surfactants can enable quantum dot self-assembly where it otherwise would\nnot occur."
    },
    {
        "anchor": "Fast long-wavelength exchange spin waves in partially-compensated Ga:YIG: Spin waves in yttrium iron garnet (YIG) nano-structures attract increasing\nattention from the perspective of novel magnon-based data processing\napplications. For short wavelengths needed in small-scale devices, the group\nvelocity is directly proportional to the spin-wave exchange stiffness constant\n$\\lambda_\\mathrm{ex}$. Using wave vector resolved Brillouin Light Scattering\n(BLS) spectroscopy, we directly measure $\\lambda_\\mathrm{ex}$ in Ga-substituted\nYIG thin films and show that it is about three times larger than for pure YIG.\nConsequently, the spin-wave group velocity overcomes the one in pure YIG for\nwavenumbers $k > 4$ rad/$\\mu$m, and the ratio between the velocities reaches a\nconstant value of around 3.4 for all $k > 20$ rad/$\\mu$m. As revealed by\nvibrating-sample magnetometry (VSM) and ferromagnetic resonance (FMR)\nspectroscopy, Ga:YIG films with thicknesses down to 59 nm have a low Gilbert\ndamping ($\\alpha < 10^{-3}$), a decreased saturation magnetization $\\mu_0\nM_\\mathrm{S}~\\approx~20~$mT and a pronounced out-of-plane uniaxial anisotropy\nof about $\\mu_0 H_{\\textrm{u1}} \\approx 95 $ mT which leads to an out-of-plane\neasy axis. Thus, Ga:YIG opens access to fast and isotropic spin-wave transport\nfor all wavelengths in nano-scale systems independently of dipolar effects.",
        "positive": "Graphene-ionic liquid interfacial potential drop from DFT-MD simulations: Ionic liquids (IL) are promising electrolytes for electrochemical\napplications due to their remarkable stability and high charge density.\nMolecular dynamics simulations are essential for better understanding the\ncomplex phenomena occurring at the electrode-IL interface. In this work, we\nhave studied the interface between graphene and 1-ethyl-3-methyl-imidazolium\ntetrafluoroborate IL, using density functional theory-based molecular dynamics\nsimulations at variable surface charge densities. We have disassembled the\nelectrical double layer potential drop into two main components: one involving\natomic charges and the other - dipoles. The latter component arises due to the\nelectronic polarisation of the surface and is related to concepts hotly debated\nin the literature, such as the Thomas-Fermi screening length, effective surface\ncharge plane, and quantum capacitance."
    },
    {
        "anchor": "Periodic elastic nanodomains in ultrathin tetrogonal-like BiFeO3 films: We present a synchrotron grazing incidence x-ray diffraction analysis of the\ndomain structure and polar symmetry of highly strained BiFeO3 thin films grown\non LaAlO3 substrate. We revealed the existence of periodic elastic nanodomains\nin the pure tetragonal-like BFO ultrathin films down to a thickness of 6 nm. A\nunique shear strain accommodation mechanism is disclosed. We further\ndemonstrated that the periodicity of the nanodomains increases with film\nthickness but deviates from the classical Kittel's square root law in ultrathin\nthickness regime (6 - 30 nm). Temperature-dependent experiments also reveal the\ndisappearance of periodic modulation above 90C due to a MC-MA structural phase\ntransition.",
        "positive": "Origin of Pyroelectricity in LiNbO3: We use molecular dynamics with a first-principles based shell model potential\nto study pyroelec- tricity in lithium niobate. We find that the primary\npyroelectric effect is dominant, and pyroelec- tricity can be understood simply\nfrom the anharmonic change in crystal structure with temperature and the Born\neffective charges on the ions. This opens a new experimental route to studying\npy- roelectricity, as candidate pyroelectric materials can be studied with\nX-ray diffraction as a function of temperature in conjunction with theoretical\neffective charges. We also predict an appreciable pressure effect on\npyroelectricity, which could be used to optimize materials pyroelectricity, and\nthe converse electrocaloric effect, peak as Tc is approached."
    },
    {
        "anchor": "Electronic properties and metrology of the diamond NV- center under\n  pressure: The negatively charged nitrogen-vacancy (NV-) center in diamond has realized\nnew frontiers in quantum technology. Here, the center's optical and spin\nresonances are observed under hydrostatic pressures up to 60 GPa. Our\nobservations motivate powerful new techniques to measure pressure and image\nhigh pressure magnetic and electric phenomena. Our observations further reveal\na fundamental inadequacy of the current model of the center and provide new\ninsight into its electronic structure.",
        "positive": "Non-Reciprocal Interactions Induced by Water in Confinement: Water mediates electrostatic interactions via the orientation of its dipoles\naround ions, molecules, and interfaces. This induced water polarization\nconsequently influences multiple phenomena. In particular, water polarization\nmodulated by nanoconfinement affects ion adsorption and transport, biomolecular\nself-assembly, and surface chemical reactions. Therefore, it is of paramount\nimportance to understand how water-mediated interactions change at the\nnanoscale. Here we show that near the graphene surface anion-cation\ninteractions do not obey the translational and isotropic symmetries of\nCoulomb's law. We identify a new property, referred to as non-reciprocity,\nwhich describes the non-equivalent and directional interaction between two\noppositely charged ions near the confining surface when their positions with\nrespect to the interface are exchanged. Specifically, upon exchange of the two\nions' positions along the surface normal direction the interaction energy\nchanges by about 5$k_BT$. In both cases, confinement enhances the attraction\nbetween two oppositely charged ions near the graphene surface, while\nintercalation of one ion into the graphene layers shifts the interaction to\nrepulsive. While the water permittivity in confinement is different from that\nin bulk, the effects observed here via molecular dynamics simulations and X-ray\nreflectivity experiments cannot be accounted for by current permittivity\nmodels. Our work shows that the water structure is not enough to infer\nelectrostatic interactions near interfaces."
    },
    {
        "anchor": "Temperature-dependent photo-response in multiferroic BiFeO$_3$ revealed\n  by transmission measurements: We studied the light-induced effects in BiFeO$_3$ single crystals as a\nfunction of temperature by means of optical spectroscopy. Here we report the\nobservation of several light-induced absorption features, which are discussed\nin terms of the photostriction effect and are interpreted in terms of excitons.\nThe temperature dependence of their energy position suggests a possible\ncoupling between the excitons and the lattice vibrations. Moreover, there are\nhints for anomalies in the temperature evolution of the excitonic features,\nwhich might be related to the temperature-induced magnetic phase transitions in\nBiFeO$_3$. Our findings suggest a coupling between light-induced excitons and\nthe lattice and spin degrees of freedom, which might be relevant for the\nobserved ultrafast photostriction effect in multiferroic BiFeO$_3$.",
        "positive": "An effective Landau-type model of Hf$_x$Zr$_{1-x}$O$_2$ thin film -\n  graphene nanostructure: To describe the charge-polarization coupling in the nanostructure formed by a\nthin Hf$_x$Zr$_{1-x}$O$_2$ film with a single-layer graphene as a top\nelectrode, we develop the \"effective\" Landau-Ginzburg-Devonshire model. This\napproach is based on the parametrization of the Landau expansion coefficients\nfor the polar (FE) and antipolar (AFE) orderings in thin Hf$_x$Zr$_{1-x}$O$_2$\nfilms from a limited number of polarization-field curves and hysteresis loops.\nThe Landau expansion coefficients are nonlinearly dependent on the film\nthickness h and Zr/[Hf+Zr] ratio x, in contrast to h-independent and linearly\nx-dependent expansion coefficients of a classical Landau energy. We explain the\ndependence of the Landau expansion coefficients by the strong nonmonotonic\ndependence of the polar properties on the Hf$_x$Zr$_{1-x}$O$_2$ film thickness,\ngrain size and surface energy. The proposed Landau free energy with five\n\"effective\" expansion coefficients, which are interpolation functions of x and\nh, describes the continuous transformation of polarization dependences on\napplied electric field and hysteresis loop shapes induced by the changes of x\nand h in the range 0 < x < 1 and 5 nm < h < 35 nm. Using the effective free\nenergy, we demonstrated that the polarization of Hf$_x$Zr$_{1-x}$O$_2$ films\ninfluences strongly on the graphene conductivity, and the full correlation\nbetween the distribution of polarization and charge carriers in graphene is\nrevealed. In accordance with our modeling, the polarization of the (5 - 25) nm\nthick Hf$_x$Zr$_{1-x}$O$_2$ films, which are in the ferroelectric-like or\nantiferroelectric-like states for the chemical compositions 0.35 < x < 0.95,\ndetermine the concentration of carriers in graphene and can control its field\ndependence. The result can be promising for creation of next generation\nSi-compatible nonvolatile memories and graphene-ferroelectric FETs."
    },
    {
        "anchor": "Comments on \"Recent Developments in Plasmon-Assisted Photocatalysis -- a\n  Personal Perspective\": The authors of preprint arXiv:2009.00286 and paper Appl. Phys. Lett. 117,\n130501 (2020), Y. Sivan and Y. Dubi, made several wrong and inconsistent\ncomments on our papers [J. Phys. Chem. C 117, 16616-16631 (2013), ACS Photonics\n4 (11), 2759-2781 (2017)]. Moreover, the authors of arXiv:2009.00286 addressed\nin their comments features that were not present in our paper [ACS Photonics 4\n(11), 2759-2781 (2017)]. In this document we go through the comments made in\narXiv:2009.00286, which we found to be wrong and misleading.",
        "positive": "Importance of correlation effects in hcp iron revealed by a\n  pressure-induced electronic topological transition: We discover that hcp phases of Fe and Fe0.9Ni0.1 undergo an electronic\ntopological transition at pressures of about 40 GPa. This topological change of\nthe Fermi surface manifests itself through anomalous behavior of the Debye\nsound velocity, c/a lattice parameter ratio and M\\\"ossbauer center shift\nobserved in our experiments. First-principles simulations within the dynamic\nmean field approach demonstrate that the transition is induced by many-electron\neffects. It is absent in one-electron calculations and represents a clear\nsignature of correlation effects in hcp Fe."
    },
    {
        "anchor": "Tuning the magnetic exchange via a control of orbital hybridization in\n  Cr2(Te1-xWx)O6: We report the complex magnetic phase diagram and electronic structure of\nCr2(Te1-xWx)O6 systems. While compounds with different x values possess the\nsame crystal structure, they display different magnetic structures below and\nabove xc = 0.7, where both the transition temperature TN and sublattice\nmagnetization (Ms) reach a minimum. Unlike many known cases where magnetic\ninteractions are controlled either by injection of charge carriers or by\nstructural distortion induced via chemical doping, in the present case it is\nachieved by tuning the orbital hybridization between Cr 3d and O 2p orbitals\nthrough W 5d states. The result is supported by ab-initio electronic structure\ncalculations. Through this concept, we introduce a new approach to tune\nmagnetic and electronic properties via chemical doping.",
        "positive": "Revealing the role of \u03a33{112} Si grain boundary local structures\n  in impurity segregation: The interfacial structure of a silicon grain boundary (Si-GB) plays a\ndecisive role on its chemical functionalization and has implications in diverse\nphysical-chemical properties of the material. Therefore, GB interface is\nparticularly relevant when the material is employed in high performance\ntechnological applications. Here, we studied from first principles the role of\nGB interface by providing an atomistic understanding of two different\n$\\Sigma$3\\{112\\} Si-GB models. These models are (1$\\times$1) and (1$\\times$2)\n$\\Sigma$3\\{112\\} Si-GBs which lead to different structural reconstruction.\nStarting from these two models, we have shown that geometry optimization has an\nimportant role on the structural reconstruction of the GB interface and\ntherefore on its properties. For this reason, we discussed different\nmethodologies to define an optimal relaxation protocol. The influence of the\nlocal structures in (1$\\times$1) and (1$\\times$2) models have also been\ninvestigated in the presence of vacancies where different light impurities of\ndifferent valency (C, N, H, O) can segregate. We studied how local structures\nin (1$\\times$1) and (1$\\times$2) models are modified by the presence of\nvacancies and impurities. These structural modifications have been correlated\nwith the changes of the energetics and electronic properties of the GBs. The\nbehavior of (1$\\times$1) and (1$\\times$2) models demonstrated to be\nsignificantly different. The interaction with vacancies and the segregation of\nC, N, H and O are significantly different depending on the type of local\nstructures present in $\\Sigma$3\\{112\\} Si-GB."
    },
    {
        "anchor": "Third-order charge transport in a magnetic topological semimetal: Magnetic topological materials and their physical signatures are a focus of\ncurrent research. Here, by first-principles calculations and symmetry analysis,\nwe reveal topological semimetal states in an existing antiferromagnet ThMn2Si2.\nDepending on the N\\'eel vector orientation, the topological band crossings near\nthe Fermi level form either a double-nodal loop or two pairs of Dirac\npoints,which are all fourfold degenerate and robust under spin-orbit coupling.\nThese topological features produce large Berry connection polarizability, which\nleads to enhanced nonlinear transport effects. Particularly, we evaluate the\nthird order current response, which dominates the transverse charge current. We\nshow that the nonlinear response can be much more sensitive to topological\nphase transitions than linear response, which offers a powerful tool for\ncharacterizing magnetic topological semimetals.",
        "positive": "A new interpretation of the dynamic structure model of ion transport in\n  molten and solid glasses: We explore progress in understanding the behaviour of cation conducting\nglasses, within the context of an evolving ''dynamic structure model'' (DSM).\nThis behaviour includes: in single cation glasses a strong dependence of ion\nmobility on concentration, and in mixed cation glasses a range of anomalies\nknown collectively as the mixed alkali effect. We argue that this rich\nphenomenology arises from the emergence during cooling of a well-defined\nstructure in glass melts resulting from the interplay of chemical interactions\nand thermally driven ionic motions. The new DSM proposes the existence of a new\nsite relaxation process, involving the shrinkage of empty $\\bar A$ sites (thus\ntailored to the needs of $A^+$ ions), and the concurrent emergence of empty\n$C'$&#146;sites, which interrupt the conduction pathways. This reduction of\n$\\bar A$ sites is responsible in the molten glass for the sharp fall in\nconductivity as temperature drops towards $T_g$. The $C'$ sites play an\nimportant role also in the mixed alkali effect, especially in regard to the\npronounced asymmetries in diffusion behaviour of dissimilar cations."
    },
    {
        "anchor": "Origin of Reduced Polaron Recombination in Organic Semiconductor Devices: We propose a model to explain the reduced bimolecular recombination rate\nfound in state-of-the-art bulk heterojunction solar cells. When compared to the\nLangevin recombination, the experimentally observed rate is one to four orders\nof magnitude lower, but gets closer to the Langevin case for low temperatures.\nOur model considers the organic solar cell as device with carrier concentration\ngradients, which form due to the electrode/blend/electrode device\nconfiguration. The resulting electron concentration under working conditions of\na solar cell is higher at the cathode than at the anode, and vice versa for\nholes. Therefore, the spatially dependent bimolecular recombination rate,\nproportional to the local product of electron and hole concentration, is much\nlower as compared to the calculation of the recombination rate based on the\nextracted and thus averaged charge carrier concentrations. We consider also the\ntemperature dependence of the recombination rate, which can for the first time\nbe described with our model.",
        "positive": "Sn delta-doping in GaAs: We have prepared a number of GaAs structures delta-doped by Sn using the\nwell-known molecular beam epitaxy growth technique. The samples obtained for a\nwide range of Sn doping densities were characterised by magnetotransport\nexperiments at low temperatures and in high magnetic fields up to 38 T.\nHall-effect and Shubnikov-de Haas measurements show that the electron densities\nreached are higher than for other delta-dopants, like Si and Be. The maximum\ncarrier density determined by the Hall effect equals 8.4x10^13 cm^-2. For all\nsamples several Shubnikov-de Haas frequencies were observed, indicating the\npopulation of multiple subbands. The depopulation fields of the subbands were\ndetermined by measuring the magnetoresistance with the magnetic field in the\nplane of the delta-layer. The experimental results are in good agreement with\nselfconsistent bandstructure calculations. These calculation shows that in the\nsample with the highest electron density also the conduction band at the L\npoint is populated."
    },
    {
        "anchor": "Unveiling the outstanding oxygen mass transport properties of Mn-rich\n  perovskites in grain boundary-dominated La0.8Sr0.2(Mn1-xCox)0.85O3-d\n  nanostructures: Ion transport in solid-state devices is of great interest for current and\nfuture energy and information technologies. A superior enhancement of several\norders of magnitude of the oxygen diffusivity has been recently reported for\ngrain boundaries in lanthanum strontium manganites. However, the significance\nand extent of this unique phenomenon is not yet established. Here, we fabricate\na thin film continuous composition map of the La0.8Sr0.2(Mn1-xCox)0.85O3-d\nfamily revealing a substantial enhancement of the grain boundary oxygen mass\ntransport properties for the entire range of compositions. Through\nisotope-exchange depth profiling coupled to secondary ion mass spectroscopy, we\nshow that this excellent performance is not directly linked to the bulk of the\nmaterial but to the intrinsic nature of the grain boundary. In particular, the\ngreat increase of the oxygen diffusion in Mn-rich compositions unveils an\nunprecedented catalytic performance in the field of Mixed Ionic Electronic\nConductors. These results present grain boundaries engineering as a novel\nstrategy for designing highly performing materials for solid state ionics based\ndevices.",
        "positive": "Pentagons in the Si$(331)-(12\\times1)$ surface reconstruction: The microscopic structure of the high-index Si$(331)-(12\\times1)$ surface is\ninvestigated combining scanning tunneling microscopy with ab initio\ncalculations. We present a structural model of the Si(331) surface, employing a\nreconstruction element composed of six pentagons integrated to the structure of\nthe adjacent pentamer with an interstitial atom. We demonstrate that\nappropriately arranged additional pentagons significantly lower the surface\nenergy of the high-index surface. The model predicts the existence of multiple\nSi(331) buckled configurations with similar energies."
    },
    {
        "anchor": "Hyperbolicity in 2D transition metal ditellurides induced by electronic\n  bands nesting: Naturally occurring hyperbolic plasmonic media is rare, and was only recently\nobserved in the 1T$'$ phase of WTe$_2$. We elucidate on the physical origin of\nthis strong infrared hyperbolic response, and attribute it to band-nested\nanisotropic interband transitions. Such phenomenon does not occur in general\nanisotropic materials, at least not in their pristine state. However,\nband-nested anisotropic interband transitions can in principle be induced via\nproper electronic band nesting. We illustrate this principle and demonstrate a\ntopological elliptic-to-hyperbolic transition in MoTe$_2$ via strain\nengineering, which is otherwise non-hyperbolic.",
        "positive": "On the Rapid Estimation of Permeability for Porous Media Using Brownian\n  Motion Paths: We describe two efficient methods of estimating the fluid permeability of\nstandard models of porous media by using the statistics of continuous Brownian\nmotion paths that initiate outside a sample and terminate on contacting the\nporous sample. The first method associates the \"penetration depth\" with a\nspecific property of the Brownian paths, then uses the standard relation\nbetween penetration depth and permeability to calculate the latter. The second\nmethod uses Brownian paths to calculate an effective capacitance for the\nsample, then relates the capacitance, via angle-averaging theorems to the\ntranslational hydrodynamic friction of the sample. Finally, a result of\nFelderhof is used to relate the latter quantity to the permeability of the\nsample. We find that the penetration depth method is highly accurate in\npredicting permeability of porous material."
    },
    {
        "anchor": "Measurement of Surface Acoustic Wave Resonances in Ferroelectric Domains\n  by Microwave Microscopy: Surface Acoustic Wave (SAW) resonances were imaged within a closed domain in\nthe ferroelectric LiTaO$_3$ via scanning Microwave Impedance Microscopy (MIM).\nThe MIM probe is used for both SAW generation and measurement, allowing\ncontact-less measurement within a mesoscopic structure. Measurements taken over\na range of microwave frequencies are consistent with a constant acoustic\nvelocity, demonstrating the acoustic nature of the measurement.",
        "positive": "Stochastic model for transfer of gaseous particles in polymer/CNT\n  nanocomposites with interfacial regions: In this work a stochastic model of gaseous transfer in polymer/CNT\nnanocomposites is presented. The model takes into account interfacial areas,\ni.e. polymer depletion regions. The local regime of transport is controlled by\nthe density of the polymer. In a dense polymer, this regime corresponds to the\nordinary diffusion, while in free volume regions it corresponds to the\nballistic transport. The introduction of a free volume and/or a depleted\npolymer layer near to a CNT wall, leads to the emergence of anomalous\ndiffusion. We have demonstrated how the anomalous diffusion regime changes in\nthe presence of nanotubes for different distributions of polymer density. The\npresented approach allows us to describe the threshold effect in the diffusion\ncoefficient as a function of CNTs density in polymer/CNT nanocomposites."
    },
    {
        "anchor": "Ultrafast charge transfer and vibronic coupling in a laser-excited\n  hybrid inorganic/organic interface: Hybrid interfaces formed by inorganic semiconductors and organic molecules\nare intriguing materials for opto-electronics. Interfacial charge transfer is\nprimarily responsible for their peculiar electronic structure and optical\nresponse. Hence, it is essential to gain insight into this fundamental process\nalso beyond the static picture. Ab initio methods based on real-time\ntime-dependent density-functional theory coupled to the Ehrenfest molecular\ndynamics scheme are ideally suited for this problem. We investigate a\nlaser-excited hybrid inorganic/organic interface formed by the electron\nacceptor molecule 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane\n(F4TCNQ) physisorbed on a hydrogenated silicon cluster, and we discuss the\nfundamental mechanisms of charge transfer in the ultrashort time window\nfollowing the impulsive excitation. The considered interface is $p$-doped and\nexhibits charge transfer in the ground state. When it is excited by a resonant\nlaser pulse, the charge transfer across the interface is additionally\nincreased, but contrary to previous observations in all-organic donor/acceptor\ncomplexes, it is not further promoted by vibronic coupling. In the considered\ntime window of 100~fs, the molecular vibrations are coupled to the electron\ndynamics and enhance intramolecular charge transfer. Our results highlight the\ncomplexity of the physics involved and demonstrate the ability of the adopted\nformalism to achieve a comprehensive understanding of ultrafast charge transfer\nin hybrid materials.",
        "positive": "Structural, dielectric and energy storage properties of\n  BaO-Na2O-Nb2O5-P2O5 glass-ceramic: A series of (1-x)[(2BaO-0,5Na2O)-1P2O5] -xNb2O5 (BNPN, x=0,41, 0,43, 0,45,\n0,48) glass-ceramics based on phosphate glasses have been prepared via a\ncontrolled-crystallization route. The structure, dielectric properties,\ninterfacial polarization, and energy storage properties were systematically\ninvestigated. The x-ray diffraction results showed the simultaneous presence of\nBa2NaNb5O15 tungsten bronze structure (TTB) and the NaNbO3 perovskite. A stable\ndielectric constant over a temperature range from 25-200{\\deg}C, low dielectric\nlosses less than 0,03, and excellent frequency stability at room temperature\nwere obtained. The decrease in niobium content promoted TTB crystallization\nwith the improvement of the high dielectric properties of the system. The\noptimum of the dielectric constant and recoverable energy storage density were\nobtained for BNP41 crystallized at 1000{\\deg}C. Analyses of the complex\nimpedance indicated that the niobium content and crystallization temperature\naffect the interfacial polarization."
    },
    {
        "anchor": "Landau Level optical Hall effect spectroscopy on two- and\n  three-dimensional layered materials with graphene and graphite as examples: We present a comprehensive study of the band structure of two- and\nthree-dimensional hexagonal layered materials using Landau Level optical Hall\neffect spectroscopy investigations, employing graphene and graphite as model\nsystems. We study inter-Landau-level transitions in highly oriented pyrolytic\ngraphite and a stack of multilayer graphene on C-face 6\\textit{H}-SiC, using\ndata from reflection-type optical Hall effect measurements in the mid-infrared\nspectral range at sample temperatures of $T=1.5$~K and magnetic fields up to\n$B=8$~T. We describe a comprehensive dielectric polarizability model for\ninter-Landau-level transitions, which permits analysis of the optical Hall\neffect data. From their magnetic field dependence we identify sets of H- and\nK-point inter-Landau-level transitions in graphite and sets of\ninter-Landau-level transition from decoupled graphene single, and coupled\ngraphene bi-, tri-, and quad-layer for the multilayer graphene stack. For\ninter-Landau-level transitions in decoupled graphene single-layers and H-point\ntransitions in graphite we observe polarization mode preserving behavior,\nrequiring symmetric magneto-optical contributions to the corresponding\ndielectric tensors. Inter-Landau-level transitions in coupled graphene layers\nas well as K-point transitions in graphite exhibit polarization mode mixing\nbehavior, requiring antisymmetric magneto-optical contributions to the\ncorresponding dielectric tensors. From the circular-polarization-averaged\ninter-Landau-level transition energies and the energy splitting between right-\nand left-handed circular polarized inter-Landau-level transitions we determine\nthe model parameters in the Slonczewski-Weiss-McClure band structure\napproximation for two- and three-dimensional hexagonal layered materials, with\ngraphene and graphite as examples.",
        "positive": "Sign reversal of magnetoresistance and p to n transition in Ni doped ZnO\n  thin film: We report the magnetoresistance and nonlinear Hall effect studies over a wide\ntemperature range in pulsed laser deposited Ni0.07Zn0.93O thin film. Negative\nand positive contributions to magnetoresistance at high and low temperatures\nhave been successfully modeled by the localized magnetic moment and two band\nconduction process involving heavy and light hole subbands, respectively.\nNonlinearity in the Hall resistance also agrees well with the two channel\nconduction model. A negative Hall voltage has been found for T $\\gte 50 K$,\nimplying a dominant conduction mainly by electrons whereas positive Hall\nvoltage for T less than 50 K shows hole dominated conduction in this material.\nCrossover in the sign of magnetoresistance from negative to positive reveals\nthe spin polarization of the charge carriers and hence the applicability of Ni\ndoped ZnO thin film for spintronic applications."
    },
    {
        "anchor": "Formation and dynamics of small polarons on the rutile TiO$_2$(110)\n  surface: Charge trapping and formation of polarons is a pervasive phenomenon in\ntransition metal oxide compounds, in particular at the surface, affecting\nfundamental physical properties and functionalities of the hosting materials.\nHere we investigate via first-principle techniques the formation and dynamics\nof small polarons on the reduced surface of titanium dioxide, an archetypal\nsystem for polarons, for a wide range of oxygen vacancy concentrations. We\nreport how the essential features of polarons can be adequately accounted in\nterms of few quantities: the local structural and chemical environment, the\nattractive interaction between negatively charged polarons and positively\ncharged oxygen vacancies, and the spin-dependent polaron-polaron Coulomb\nrepulsion. We combined molecular dynamics simulations on realistic samples\nderived from experimental observations with simplified static models, aiming to\ndisentangle the various variables at play. We find that depending on the\nspecific trapping site, different types of polarons can be formed, with\ndistinct orbital symmetries and different degree of localization and structural\ndistortion. The energetically most stable polaron site is the subsurface Ti\natom below the undercoordinated surface Ti atom, owing to a small energy cost\nto distort the lattice and a suitable electrostatic potential. Polaron-polaron\nrepulsion and polaron-vacancy attraction determine the spatial distribution of\npolarons as well as the energy of the polaronic in-gap state. In the range of\nexperimentally reachable oxygen vacancy concentrations the calculated data are\nin excellent agreement with observations, thus validating the overall\ninterpretation.",
        "positive": "The influence of superparamagnetism on exchange anisotropy at\n  CoO/[Co/Pd] interfaces: Magnetic systems exhibiting exchange bias effect are being considered as\nmaterials for applications in data storage devices, sensors and biomedicine. As\nthe size of new mag- netic devices is being continuously reduced, the influence\nof thermally induced instabilities in magnetic order has to be taken into\naccount during their fabrication process. In this study we show the influence\nof superparamagnetism on magnetic properties of exchange-biased [CoO/Co/Pd]10\nmultilayer. We find that the process of progressive thermal blocking of the\nsuperparamagnetic clusters causes an unusually fast rise of the exchange\nanisotropy field and coercivity, and promotes the easy axis switching to\nout-of-plane direction."
    },
    {
        "anchor": "Elastic energy of multi-component solid solutions and strain origins of\n  phase stability in high-entropy alloys: The elastic energy of mixing for multi-component solid solutions is derived\nby generalizing Eshelby's sphere-in-hole model for binary alloys. By surveying\nthe dependence of the elastic energy on chemical composition and lattice\nmisfit, we propose a lattice strain coefficient {\\lambda}*. Applying to several\nhigh-entropy alloys and superalloys, we found that most solid solution alloys\nare stable when {\\lambda}*<0.16, analogous to the Hume-Rothery atomic-size rule\nfor binary alloys. We also reveal that the polydispersity index {\\delta},\nfrequently used for describing strain in multi-component alloys, is directly\nrelated to the elastic energy (e) with e=q{\\delta}^2, q being an elastic\nconstant. Furthermore, the effects of (i) the number and (ii) the atomic-size\ndistribution of constituting elements on the phase stability of high-entropy\nalloys were quantified. The present derivations open for richer considerations\nof elastic effects in high-entropy alloys, offering immediate support for\nquantitative assessments of their thermodynamic properties and studying related\nstrengthening mechanisms.",
        "positive": "Low-frequency modes in the Raman spectrum of sp-sp2 nanostructured\n  carbon: A novel form of amorphous carbon with sp-sp2 hybridization has been recently\nproduced by supersonic cluster beam deposition showing the presence in the film\nof both polyynic and cumulenic species [L. Ravagnan et al. Phys. Rev. Lett. 98,\n216103 (2007)]. Here we present a in situ Raman characterization of the low\nfrequency vibrational region (400-800 cm-1) of sp-sp2 films at different\ntemperatures. We report the presence of two peaks at 450 cm-1 and 720 cm-1. The\nlower frequency peak shows an evolution with the variation of the sp content\nand it can be attributed, with the support of density functional theory (DFT)\nsimulations, to bending modes of sp linear structures. The peak at 720 cm-1\ndoes not vary with the sp content and it can be attributed to a feature in the\nvibrational density of states activated by the disorder of the sp2 phase."
    },
    {
        "anchor": "Failure mechanisms of single-crystal silicon electrodes in lithium-ion\n  batteries: Long-term durability is a major obstacle limiting the widespread use of\nlithium ion batteries (LIBs) in heavy-duty applications and others demanding\nextended lifetime. As one of the root causes of degradation and failure of\nbattery performance, the electrode failure mechanisms are still unknown. Here,\nwe reveal the fundamental fracture mechanisms of single-crystal silicon\nelectrodes over extended lithiation/delithiation cycles, using electrochemical\ntesting, microstructure characterization, fracture mechanics, and finite\nelement analysis. Anisotropic lithium invasion causes crack initiation\nperpendicular to the electrode surface, followed by growth through the\nelectrode thickness. The low fracture energy of the lithiated/unlithiated\nsilicon interface provides a weak microstructural path for crack deflection,\naccounting for the crack patterns and delamination observed after repeated\ncycling. Based on this physical understanding, we demonstrate how electrolyte\nadditives can heal electrode cracks and provide strategies to enhance the\nfracture resistance in future LIBs from surface chemical, electrochemical, and\nmaterial science perspectives.",
        "positive": "Engineering chromium related single photon emitters in single crystal\n  diamond: Color centers in diamond as single photon emitters, are leading candidates\nfor future quantum devices due to their room temperature operation and\nphotostability. The recently discovered chromium related centers are\nparticularly attractive since they possess narrow bandwidth emission and a very\nshort lifetime. In this paper we investigate the fabrication methodologies to\nengineer these centers in monolithic diamond. We show that the emitters can be\nsuccessfully fabricated by ion implantation of chromium in conjunction with\noxygen or sulfur. Furthermore, our results indicate that the background\nnitrogen concentration is an important parameter, which governs the probability\nof success to generate these centers."
    },
    {
        "anchor": "Antiferromagnetic $\u03b1$-MnTe: Molten-Salt-Assisted Chemical Vapor\n  Deposition Growth and Magneto-Transport Properties: Antiferromagnetic (AF) materials are attracting increasing interest of\nresearch in magnetic physics and spintronics. Here, we report controllable\nsynthesis of room-temperature AF $\\alpha$-MnTe nanocrystals (N\\'eel temperature\n~ 307 K) via molten-salt-assisted chemical vapor deposition method. The growth\nkinetics are investigated regarding the dependence of flake dimension and\nmacroscopic shape on growth time and temperature. The high crystalline quality\nand atomic structure are confirmed by various crystallographic characterization\nmeans. Cryogenic magneto-transport measurements reveal anisotropic\nmagnetoresistance (MR) response and a complicated dependence of MR on\ntemperature, owing to the subtle competition among multiple scattering\nmechanisms of thermally excited magnetic disorders (magnon drag), magnetic\ntransition and thermally populated lattice phonons. Overall positive MR\nbehavior with twice transitions in magnitude is observed when out-of-plane\nexternal magnetic field ($B$) is applied, while a transition from negative to\npositive MR response is recorded when in-plane $B$ is applied. The rich\nmagnetic transport properties render $\\alpha$-MnTe a promising material for\nexploiting functional components in magnetic devices.",
        "positive": "Photoinduced features of energy band gap in quaternary Cu2CdGeS4\n  crystals: Quaternary chalcogenide crystal Cu2CdGeS4 was studied both experimentally and\ntheoretically in the present paper. Investigations of polarized fundamental\nabsorption spectra demonstrated a high sensitivity to external light\nillumination. The photoinduced changes were studied using the cw 532 nm green\nlaser with energy density about 0.4 J/cm2. The spectral maximum of the\nphotoinduced anisotropy was observed at spectral energies equal to about 1.4 eV\n(energy gap equal to about 1.85 eV) corresponding to maximal density of the\nintrinsic defect levels. Spectroscopic measurements were performed for\npolarized and un-polarized photoinducing laser light to separate contribution\nof the intrinsic defect states from the pure states of the valence and\nconduction bands. To understand the origin of the observed photoinduced\nabsorption near the fundamental edge, the benchmark first-principles\ncalculations of the structural, electronic, optical and elastic properties of\nCu2CdGeS4 were performed in the general gradient approximation (GGA) and local\ndensity approximation (LDA) approaches. The calculated dielectric function and\noptical absorption spectra exhibit some anisotropic behavior within the\n0.15...0.20 eV energy range near the absorption edge; the optical anisotropy\nwas also found in the deep inter-band transition spectral range. Peculiar\nfeatures of chemical bonds in Cu2CdGeS4 were revealed by studying the electron\ndensity distribution. Possible intrinsic defects are shown to affect\nconsiderably the optical absorption spectra. Pressure effects on the structural\nand electronic properties were modeled by optimizing the crystal structure and\ncalculating all relevant properties at elevated hydrostatic pressure. The first\nestimations of the bulk modulus (69 GPa (GGA) or 91 GPa (LDA)) and its pressure\nderivative for Cu2CdGeS4 are reported."
    },
    {
        "anchor": "Tracking ultrafast change of multiterahertz broadband response functions\n  in a photoexcited Dirac semimetal Cd$_3$As$_2$ thin film: The electromagnetic response of Dirac semimetals in the infrared and\nterahertz frequency ranges is attracting growing interest for potential\napplications in optoelectronics and nonlinear optics. The interplay between the\nfree-carrier response and interband transitions in the gapless, linear\ndispersion relation plays a key role in enabling novel functionalities. Here we\ninvestigate ultrafast dynamics in thin films of a photoexcited Dirac semimetal\nCd$_3$As$_2$ by probing the broadband response functions as complex quantities\nin the multiterahertz region (10-45 THz, 40-180 meV, or 7-30 $\\mu$m), which\ncovers the crossover between the inter and intraband response. We resolve\ndynamics of the photoexcited nonthermal electrons which merge with originally\nexisting carriers to form a single thermalized electron gas and how it is\nfacilitated by high-density excitation. We also demonstrate that a large\nreduction of the refractive index by 80% dominates the nonequilibrium infrared\nresponse, which can be utilized for designing ultrafast switches in active\noptoelectronics.",
        "positive": "Magnetic interactions of substitutional Mn pairs in GaAs: We employ a kinetic-exchange tight-binding model to calculate the magnetic\ninteraction and anisotropy energies of a pair of substitutional Mn atoms in\nGaAs as a function of their separation distance and direction. We find that the\nmost energetically stable configuration is usually one in which the spins are\nferromagnetically aligned along the vector connecting the Mn atoms. The\nferromagnetic configuration is characterized by a splitting of the topmost\nunoccupied acceptor levels, which is visible in scanning tunneling microscope\nstudies when the pair is close to the surface and is strongly dependent on pair\norientation. The largest acceptor splittings occur when the Mn pair is oriented\nalong the <110> symmetry direction, and the smallest when they are oriented\nalong <100>. We show explicitly that the acceptor splitting is not simply\nrelated to the effective exchange interaction between the Mn local moments. The\nexchange interaction constant is instead more directly related to the width of\nthe distribution of all impurity levels -- occupied and unoccupied. When the Mn\npair is at the (110) GaAs surface, both acceptor splitting and effective\nexchange interaction are very small except for the smallest possible Mn\nseparation."
    },
    {
        "anchor": "Soft-Chemical Synthesis, Structure Evolution, and Insulator-to-Metal\n  Transition in a Prototypical Metal Oxide, \u03bb-RhO$_2$: ${\\lambda}$-RhO$_2$, a prototype 4d transition metal oxide, has been prepared\nby oxidative delithiation of spinel LiRh$_2$O$_4$ using ceric ammonium nitrate.\nAverage-structure studies of this RhO$_2$ polytype, including synchrotron\npowder X-ray diffraction and electron diffraction, indicate the room\ntemperature structure to be tetragonal, in the space group I41/amd, with a\nfirst-order structural transition to cubic Fd-3m at T = 345 K on warming.\nSynchrotron X-ray pair distribution function analysis and $^7$Li solid state\nnuclear magnetic resonance measurements suggest that the room temperature\nstructure displays local Rh-Rh bonding. The formation of these local dimers\nappears to be associated with a metal-to insulator transition with a\nnon-magnetic ground state, as also supported by density functional theory-based\nelectronic structure calculations. This contribution demonstrates the power of\nsoft chemistry to kinetically stabilize a surprisingly simple binary oxide\ncompound.",
        "positive": "Electronic Correlation-driven Exotic Quantum Phase Transitions in\n  Infinite-layer Manganese Oxide: Despite the intensive interest in copper- and nickel-based superconductivity\nin infinite-layer structures, the physical properties of many other\ninfinite-layer transition-metal oxides remain largely unknown. Here we unveil,\nby the first-principles calculations, the electronic correlation-driven quantum\nphase transitions in infinite-layer SrMnO2, where spin and charge orders are\nstrongly interwoven. At weak electronic correlation region, SrMnO2 is a\nferromagnetic metal with anisotropic spin transportation, as a promising spin\nvalve under room-temperature. At middle electronic correlation region, a\nstructural transition accompanied by charge/bond disproportion occurs as a\nconsequence of Fermi surface nesting, resulting in a ferromagnetic insulator\nwith reduced Curie temperature. At strong electronic correlation region,\nanother structural transition occurs that drives the system into degenerately\nantiferromagnetic insulators with tunable magnetic order by piezoelectricity, a\nnew type of multiferroics. Therefore, infinite-layer SrMnO2 is possibly a\nunique system on the quantum critical point, where electronic correlation can\ninduce noticeable Fermi surface evolutions and small perturbations can realize\nremarkable quantum phase transitions."
    },
    {
        "anchor": "White-Light Emission from Annealed ZnO:Si Nanocomposite Thin Films: As grown ZnO:Si nanocomposites of different compositional ratios were\nfabricated by thermal evaporation techniques. These films were subjected to\npost deposition annealing under high vacuum at a temperature of $\\rm 250C^o$\nfor 90min. The photoluminescence (PL) spectra of annealed samples have shown\nmarked improvements both in terms of intensity and broadening. For the first\ntime in ZnO:Si nanocomposite films we see huge UV, red and orange peaks at 310,\n570 and 640nm. Structural and Raman analysis show formation of a Zn-Si-O shell\naround ZnO nano clusters wherein on heating $\\rm Zn_2SiO_4$ compound forms. The\nnew emissions are due to $\\rm Zn_2SiO_4$ which completes white light spectrum.",
        "positive": "Temperature dependence of (111) and (110) ceria surface energy: High temperature properties of ceria surfaces are important for many\napplications. Here we report the temperature dependences of surface energy for\nthe (111) and (110) CeO2 obtained in the framework of the extended two-stage\nupsampled thermodynamic integration using Langevin dynamics (TU-TILD). The\nmethod was used together with machinelearning potentials called moment tensor\npotentials (MTPs), which were fitted to the results of the ab initio MD\ncalculations for (111) and (110) CeO2 at different temperatures. The parameters\nof MTPs training and fitting were tested and the optimal algorithm for the\nceria systems was proposed. We found that the temperature increases from 0 K to\n2100 K led to the decrease of the Helmholtz free energy of (111) CeO2 from 0.78\nJ/m2 to 0.64 J/m2. The energy of (110) CeO2 dropped from 1.19 J/m2 at 0 K to\n0.92 J/m2 at 1800 K. We show that it is important to take anharmonicity into\naccount as simple consideration of volume expansion gives wrong temperature\ndependences of the surface energies."
    },
    {
        "anchor": "Strain Engineering of Selective Chemical Adsorption on Monolayer MoS_2: Nanomaterials are prone to influence by chemical adsorption because of their\nlarge surface to volume ratios. This enables sensitive detection of adsorbed\nchemical species which, in turn, can tune the property of the host material.\nRecent studies discovered that single and multilayer molybdenum disulfide\n(MoS_2) films are ultra sensitive to several important environmental molecules.\nHere we report new findings from ab initio calculations that reveal\nsubstantially enhanced adsorption of NO and NH3 on strained monolyaer MoS2 with\nsignificant impact on the properties of the adsorbates and MoS2 layer. The\nmagnetic moment of adsobed NO can be turned between 0 and 1 uB, strain also\ninduces an electronic phase transition between half-metal and metal. Adsorption\nof NH3 weakens the MoS2 layer considerably, which explains the large discrepacy\nbetween the experimentally measured strength and breaking strain of MoS2 film\nfrom previous theoretical predictions. On the other hand, adsorption of NO2, CO\nand CO2 is insensitive to the strain condition in the MoS2 layer. This\ncontrasting behavior allows sensitive strain engineering of selective chemical\nadsorption on MoS2 with effective tuning of mechanical, electronic and magnetic\nproperties. These result suggest new design strategies for constructing MoS2\nbased ultrahigh sensitivity nanoscale sensor and electromechanical devices.",
        "positive": "A ferromagnetic Eu-Pt surface compound grown below hexagonal boron\n  nitride: One of the fundamental applications for monolayer-thick 2D materials is their\nuse as protective layers of metal surfaces and in-situ intercalated reactive\nmaterials in ambient conditions. Here we investigate the structural,\nelectronic, and magnetic properties, as well as the chemical stability in air\nof a very reactive metal, Europium, after intercalation between a hexagonal\nboron nitride (hBN) layer and a Pt substrate. We demonstrate that Eu\nintercalation leads to a hBN-covered ferromagnetic EuPt$_2$ surface alloy with\ndivalent Eu$^{2+}$ atoms at the interface. We expose the system to ambient\nconditions and find a partial conservation of the di-valent signal and hence\nthe Eu-Pt interface. The use of a curved Pt substrate allows us to explore the\nchanges in the Eu valence state and the ambient pressure protection at\ndifferent substrate planes. The interfacial EuPt$_2$ surface alloy formation\nremains the same, but the resistance of the protecting hBN layer to ambient\nconditions is reduced, likely due to a rougher surface and a more discontinuous\nhBN coating."
    },
    {
        "anchor": "Ordering and multiple phase transitions in ultra-thin nickelate\n  superlattices: We interpret via advanced ab initio calculations the multiple phase\ntransitions observed recently in ultra-thin LaNiO$_{3}$/LaAlO$_{3}$\nsuperlattices. The ground state is insulating, charge-ordered, and\nantiferromagnetic due to concurrent structural distortion and weak valency\ndisproportionation. We infer distinct transitions at 40 K and 150 K,\nrespectively, from antiferromagnetic order to moment disorder, and from\nstructurally-dimerized insulator to an undistorted metallic Pauli paramagnet\n(exhibiting a cuprate-like Fermi surface). The results are in satisfactory\nagreement with experiment.",
        "positive": "Gating effects in antiferromagnetic CuMnAs: Antiferromagnets (AFs) attract much attention due to potential applications\nin spintronics. Both the electric current and the electric field are considered\nas tools suitable to control properties and the N\\'eel vector direction of AFs.\nAmong AFs, CuMnAs has been shown to exhibit specific properties that result in\nthe existence of the current-induced spin-orbit torques commensurate with spin\ndirections and topological Dirac quasiparticles. Here, we report on the\nobservation of a reversible effect of an electric field on the resistivity of\nCuMnAs thin films, employing ionic liquid as a gate insulator. The data allow\nto determine the carrier type, concentration, and mobility independently of the\nHall effect that may be affected by an anomalous component."
    },
    {
        "anchor": "Self-Assembled formation of long, thin, and uncoalesced GaN nanowires on\n  crystalline TiN films: We investigate in detail the self-assembled nucleation and growth of GaN\nnanowires by molecular beam epitaxy on crystalline TiN films. We demonstrate\nthat this type of substrate allows the growth of long and thin GaN nanowires\nthat do not suffer from coalescence, which is in contrast to the growth on Si\nand other substrates. Only beyond a certain nanowire length that depends on the\nnanowire number density and exceeds here 1.5 {\\mu}m, coalescence takes place by\nbundling, i.e. the same process as on Si. By analyzing the nearest neighbor\ndistance distribution, we identify diffusion-induced repulsion of neighboring\nnanowires as the main mechanism limiting the nanowire number density during\nnucleation on TiN. Since on Si the final number density is determined by\nshadowing of the impinging molecular beams by existing nanowires, it is the\ndifference in adatom surface diffusion that enables on TiN the formation of\nnanowire ensembles with reduced number density. These nanowire ensembles\ncombine properties that make them a promising basis for the growth of\ncore-shell heterostructures.",
        "positive": "Probing Carrier Dynamics in sp$^{3}$-Functionalized Single-Walled Carbon\n  Nanotubes with Time-Resolved Terahertz Spectroscopy: The controlled introduction of covalent sp$^{3}$ defects into semiconducting\nsingle-walled carbon nanotubes (SWCNTs) gives rise to exciton localization and\nred-shifted near-infrared luminescence. The single-photon emission\ncharacteristics of these functionalized SWCNTs make them interesting candidates\nfor electrically driven quantum light sources. However, the impact of sp$^{3}$\ndefects on the carrier dynamics and charge transport in carbon nanotubes\nremains an open question. Here, we use ultrafast, time-resolved optical-pump\nterahertz-probe spectroscopy as a direct and quantitative technique to\ninvestigate the microscopic and temperature-dependent charge transport\nproperties of pristine and functionalized (6,5) SWCNTs in dispersions and thin\nfilms. We find that sp$^{3}$ functionalization increases charge carrier\nscattering, thus reducing the intra-nanotube carrier mobility. In combination\nwith electrical measurements of SWCNT network field-effect transistors, these\ndata enable us to distinguish between contributions of intra-nanotube band\ntransport, sp$^{3}$ defect scattering and inter-nanotube carrier hopping to the\noverall charge transport properties of nanotube networks."
    },
    {
        "anchor": "Theoretical investigation of methane under pressure: We present computer simulations of liquid and solid phases of condensed\nmethane at pressures below 25 GPa, between 150 and 300 K, where no appreciable\nmolecular dissociation occurs. We used molecular dynamics (MD) and metadynamics\ntechniques, and empirical potentials in the rigid molecule approximation, whose\nvalidity was confirmed a posteriori by carrying out it ab initio MD simulations\nfor selected pressure and temperature conditions. Our results for the melting\nline are in satisfactory agreement with existing measurements. We find that the\nfcc crystal transforms into a hcp structure with 4 molecules per unit cell (B\nphase) at about 10 GPa and 150 K, and that the B phase transforms into a\nmonoclinic high pressure phase above 20 GPa. Our results for solid/solid phase\ntransitions are consistent with those of Raman studies but the phase boundaries\nestimated in our calculations are at higher pressure than those inferred from\nspectroscopic data.",
        "positive": "Optical markers of magnetic phase transition in CrSBr: Here, we investigate the role of the interlayer magnetic ordering of CrSBr in\nthe framework of $\\textit{ab initio}$ calculations and by using optical\nspectroscopy techniques. These combined studies allow us to unambiguously\ndetermine the nature of the optical transitions. In particular,\nphotoreflectance measurements, sensitive to the direct transitions, have been\ncarried out for the first time. We have demonstrated that optically induced\nband-to-band transitions visible in optical measurement are remarkably well\nassigned to the band structure by the momentum matrix elements and energy\ndifferences for the magnetic ground state (A-AFM). In addition, our study\nreveals significant differences in electronic properties for two different\ninterlayer magnetic phases. When the magnetic ordering of A-AFM to FM is\nchanged, the crucial modification of the band structure reflected in the\ndirect-to-indirect band gap transition and the significant splitting of the\nconduction bands along the $\\Gamma-Z$ direction are obtained. In addition,\nRaman measurements demonstrate a splitting between the in-plane modes\n$B^2_{2g}$/$B^2_{3g}$, which is temperature dependent and can be assigned to\ndifferent interlayer magnetic states, corroborated by the DFT+U study.\nMoreover, the $B^2_{2g}$ mode has not been experimentally observed before.\nFinally, our results point out the origin of interlayer magnetism, which can be\nattributed to electronic rather than structural properties. Our results reveal\na new approach for tuning the optical and electronic properties of van der\nWaals magnets by controlling the interlayer magnetic ordering in adjacent\nlayers."
    },
    {
        "anchor": "Disentangling structural and kinetic components of the\n  \u03b1-relaxation in supercooled metallic liquids: The particle motion associated to the {\\alpha}-relaxation in supercooled\nliquids is still challenging scientists due to its difficulty to be probed\nexperimentally. By combining synchrotron techniques, we found the existence of\nmicroscopic structure-dynamics relationships in Pt42.5Cu27Ni9.5P21 and\nPd42.5Cu27Ni9.5P21 liquids which allows us to disentangle structural and\nkinetic contributions to the {\\alpha}-process. While the two alloys show\nsimilar kinetic fragilities, their structural fragilities differ and correlate\nwith the temperature dependence of the stretching parameter describing the\ndecay of the density fluctuations. This implies that the evolution of dynamical\nheterogeneities in supercooled alloys is determined by the rigidity of the melt\nstructure. We find also that the atomic motion not only reflects the\ntopological order but also the chemical short-range order, which can lead to a\nsurprising slowdown of the {\\alpha}-process at the mesoscopic length scale.\nThese results will contribute to the comprehension of the glass transition,\nwhich is still missing.",
        "positive": "Hydrogen Surfactant Assisted Coherent Growth of GaN on ZnO Substrate: Heterostructures of wurtzite based devices have attracted great research\ninterests since the tremendous success of GaN in light emitting diodes (LED)\nindustry. Among the possible heterostructure material candidates, high quality\nGaN thin films on inexpensive and lattice matched ZnO substrate are both\ncommercially and technologically desirable. However, the energy of ZnO polar\nsurfaces is much lower than that of GaN polar surfaces. Therefore, the\nintrinsic wetting condition forbids such heterostructures. As a result, poor\ncrystal quality and 3D growth mode were obtained. To dramatically change the\ngrowth mode of the heterostructure, we propose to use hydrogen as a surfactant,\nconfirmed by our first principles calculations. Stable H involved surface\nconfigurations and interfaces are investigated, with the help of newly\ndeveloped algorithms. By applying the experimental Gibbs free energy of H$_2$,\nwe also predict the temperature and chemical potential of H, which is critical\nin experimental realizations of our strategy. This novel approach will for the\nfirst time make the growth of high quality GaN thin films on ZnO substrates\npossible. We believe that our new strategy may reduce the manufactory cost and\nimprove the crystal quality and the efficiency of GaN based devices."
    },
    {
        "anchor": "Tracing potential energy surfaces of electronic excitations via their\n  transition origins: application to Oxirane: We show that the transition origins of electronic excitations identified by\nquantified natural transition orbital (QNTO) analysis can be employed to\nconnect potential energy surfaces (PESs) according to their character across a\nwiderange of molecular geometries. This is achieved by locating the switching\nof transition origins of adiabatic potential surfaces as the geometry changes.\nThe transition vectors for analysing transition origins are provided by linear\nresponse time-dependent density functional theory (TDDFT) calculations under\nthe Tamm-Dancoff approximation. We study the photochemical CO ring opening of\noxirane as an example and show that the results corroborate the traditional\nGomer-Noyes mechanism derived experimentally. The knowledge of specific states\nfor the reaction also agrees well with that given by previous theoretical work\nusing TDDFT surface-hopping dynamics that was validated by high-quality quantum\nMonte Carlo calculations. We also show that QNTO can be useful for considerably\nlarger and more complex systems: by projecting the excitations to those of a\nreference oxirane molecule, the approach is able to identify and analyse\nspecific excitations of a trans-2,3-diphenyloxirane molecule.",
        "positive": "Surface relaxation and ferromagnetism of Rh(001): The significant discrepancy between first-principles calculations and\nexperimental analyses for the relaxation of the (001) surface of rhodium has\nbeen a puzzle for some years. In this paper we present density functional\ntheory calculations using the local-density approximation and the generalized\ngradient approximation of the exchange-correlation functional. We investigate\nthe thermal expansion of the surface and the possibility of surface magnetism.\nThe results throw light on several, hitherto overlooked, aspects of metal\nsurfaces. We find, that, when the free energy is considered, density-functional\ntheory provides results in good agreement with experiments."
    },
    {
        "anchor": "Optical scattering resonances of single plasmonic nanoantennas: We investigate the far-field optical resonances of individual dimer\nnanoantennas using confocal scattering spectroscopy. Experiments on a\nsingle-antenna array with varying arm lengths and interparticle gap sizes show\nlarge spectral shifts of the plasmon modes due to a combination of geometrical\nresonances and plasmon hybridization. All resonances are considerably broadened\ncompared to those of small nanorods in the quasistatic limit, which we\nattribute to a greatly enhanced radiative damping of the antenna modes. The\nscattering spectra are compared with rigorous model calculations that\ndemonstrate both the near-field and far-field characteristics of a half-wave\nantenna.",
        "positive": "Perspective: Exciton polarons in two-dimensional hybrid metal-halide\n  perovskites: While polarons --- charges bound to a lattice deformation induced by\nelectron-phonon coupling --- are primary photoexcitations at room temperature\nin bulk metal-halide hybrid organic-inorganic perovskites (HOIP), excitons ---\nCoulomb-bound el\\-ectron-hole pairs --- are the stable quasi-particles in their\ntwo-dimensional (2D) analogues. Here we address the fundamental question: are\npolaronic effects consequential for excitons in 2D-HIOPs? Based on our recent\nwork, we argue that polaronic effects are manifested intrinsically in the\nexciton spectral structure, which is comprised of multiple non-degenerate\nresonances with constant inter-peak energy spacing. We highlight our own\nmeasurements of population and dephasing dynamics that point to the apparently\ndeterministic role of polaronic effects in excitonic properties. We contend\nthat an interplay of long-range and short-range exciton-lattice couplings give\nrise to exciton polarons, a character that fundamentally establishes their\neffective mass and radius, and consequently, their quantum dynamics. Finally,\nwe highlight opportunities for the community to develop the rigorous\ndescription of exciton polarons in 2D-HIOPs to advance their fundamental\nunderstanding as model systems for condensed-phase materials in which\nlattice-mediated correlations are fundamental to their physical properties."
    },
    {
        "anchor": "Non-destructive measurement of in-operando lithium concentration in\n  batteries via x-ray Compton scattering: Non-destructive determination of lithium distribution in a working battery is\nkey for addressing both efficiency and safety issues. Although various\ntechniques have been developed to map the lithium distribution in electrodes,\nthese methods are mostly applicable to test cells. Here we propose the use of\nhigh-energy x-ray Compton scattering spectroscopy to measure the local lithium\nconcentration in closed electrochemical cells. A combination of experimental\nmeasurements and parallel first-principles computations is used to show that\nthe shape parameter S of the Compton profile is linearly proportional to\nlithium concentration and thus provides a viable descriptor for this important\nquantity. The merits and applicability of our method are demonstrated with\nillustrative examples of LixMn2O4 cathodes and a working commercial lithium\ncoin battery CR2032.",
        "positive": "Strong light-matter coupling in lead halide perovskite quantum dot\n  solids: Strong coupling between lead halide perovskite materials and optical\nresonators enables both the polaritonic control of the photophysical properties\nof these emerging semiconductors and the observation of novel fundamental\nphysical phenomena. However, the difficulty to achieve optical-quality\nperovskite quantum dot (PQD) films showing well-defined excitonic transitions\nhas prevented the study of strong light-matter coupling in these materials,\ncentral to the field of optoelectronics. Herein we demonstrate the formation at\nroom temperature of multiple cavity exciton-polaritons in metallic resonators\nembedding highly transparent Cesium Lead Bromide quantum dot (CsPbBr3-QD)\nsolids, revealed by a significant reconfiguration of the absorption and\nemission properties of the system. Our results indicate that the effects of\nbiexciton interaction or large polaron formation, frequently invoked to explain\nthe properties of PQDs, are seemingly absent or compensated by other more\nconspicuous effects in the CsPbBr3-QD optical cavity. We observe that strong\ncoupling enables a significant reduction of the photoemission linewidth, as\nwell as the ultrafast switching of the optical absorption, controllable by\nmeans of the excitation fluence. We find that the interplay of the polariton\nstates with the large dark state reservoir play a decisive role in determining\nthe dynamics of the emission and transient absorption properties of the\nhybridized light-quantum dot solid system. Our results open the route for the\ninvestigation of PQD solids as polaritonic optoelectronic materials."
    },
    {
        "anchor": "Anomalous Nernst and Hall effects in magnetized platinum and palladium: We study the anomalous Nernst effect (ANE) and anomalous Hall effect (AHE) in\nproximity-induced ferromagnetic palladium and platinum which is widely used in\nspintronics, within the Berry phase formalism based on the relativistic band\nstructure calculations. We find that both the anomalous Hall ($\\sigma_{xy}^A$)\nand Nernst ($\\alpha_{xy}^A$) conductivities can be related to the spin Hall\nconductivity ($\\sigma_{xy}^S$) and band exchange-splitting ($\\Delta_{ex}$) by\nrelations $\\sigma_{xy}^A =\\Delta_{ex}\\frac{e}{\\hbar}\\sigma_{xy}^S(E_F)'$ and\n$\\alpha_{xy}^A =\n-\\frac{\\pi^2}{3}\\frac{k_B^2T\\Delta_{ex}}{\\hbar}\\sigma_{xy}^s(\\mu)\"$,\nrespectively. In particular, these relations would predict that the\n$\\sigma_{xy}^A$ in the magnetized Pt (Pd) would be positive (negative) since\nthe $\\sigma_{xy}^S(E_F)'$ is positive (negative). Furthermore, both\n$\\sigma_{xy}^A$ and $\\alpha_{xy}^A$ are approximately proportional to the\ninduced spin magnetic moment ($m_s$) because the $\\Delta_{ex}$ is a linear\nfunction of $m_s$. Using the reported $m_s$ in the magnetized Pt and Pd, we\npredict that the intrinsic anomalous Nernst conductivity (ANC) in the magnetic\nplatinum and palladium would be gigantic, being up to ten times larger than,\ne.g., iron, while the intrinsic anomalous Hall conductivity (AHC) would also be\nsignificant.",
        "positive": "A family of high-temperature ferromagnetic monolayers with locked\n  spin-dichroism-mobility anisotropy: MnNX and CrCX (X=Cl, Br, I; C=S, Se, Te): Two-dimensional magnets have received increasing attention since Cr2Ge2Te6\nand CrI3 were experimentally exfoliated and measured in 2017. Although layered\nferromagnetic metals were demonstrated at room temperature, a layered\nferromagnetic semiconductor with high Curie temperature (Tc) is yet to be\nunveiled. Here, we theoretically predicted a family of high Tc ferromagnetic\nmonolayers, namely MnNX and CrCX (X=Cl, Br and I; C=S, Se and Te). Their Tc\nvalues were predicted from over 100 K to near 500 K with Monte Carlo\nsimulations using an anisotropic Heisenberg model. Eight members among them\nshow semiconducting bandgaps varying from roughly 0.23 to 1.85 eV. These\nsemiconducting monolayers also show extremely large anisotropy, i.e. ~101 for\neffective masses and ~102 for carrier mobilities, along the two in-plane\nlattice directions of these layers. Additional orbital anisotropy leads to a\nspin-locked linear dichroism, in different from previously known circular and\nlinear dichroisms in layered materials. Together with the mobility anisotropy,\nit offers a spin-, dichroism- and mobility-anisotropy locking. These results\nmanifest the potential of this 2D family for both fundamental research and high\nperformance spin-dependent electronic and optoelectronic devices."
    },
    {
        "anchor": "Structural Determination of Nanocrystalline Si Films Using Ellipsometry\n  and Raman Spectroscopy: Single phase nano and micro crystalline silicon films deposited using SiF4/H2\nplasma at different H2 dilution levels were studied at initial and terminal\nstages of film growth with spectroscopic ellipsometry (SE), Raman scattering\n(RS) and atomic force microscopy (AFM). The analysis of data obtained from SE\nelucidates the microstructural evolution with film growth in terms of the\nchanges in crystallite sizes and their volume fractions, crystallite\nconglomeration and film morphology. The effect of H2 dilution on film\nmicrostructure and morphology, and the corroborative findings from AFM studies\nare discussed. Our SE results evince two distinct mean sizes of crystallites in\nthe material after a certain stage of film growth. The analysis of Raman\nscattering data for such films has been done using a bimodal size distribution\nof crystallite grains, which yields more accurate and physically rational\nmicrostructural picture of the material.",
        "positive": "Optically Induced Avoided Crossing in Graphene: Degenerate states in condensed matter are frequently the cause of unwanted\nfluctuations, which prevent the formation of ordered phases and reduce their\nfunctionalities. Removing these degeneracies has been a common theme in\nmaterials design, pursued for example by strain engineering at interfaces.\nHere, we explore a non-equilibrium approach to lift degeneracies in solids. We\nshow that coherent driving of the crystal lattice in bi- and multilayer\ngraphene, boosts the coupling between two doubly-degenerate modes of E1u and\nE2g symmetry, which are virtually uncoupled at equilibrium. New vibronic states\nresult from anharmonic driving of the E1u mode to large amplitdues, boosting\nits coupling to the E2g mode. The vibrational structure of the driven state is\nprobed with time-resolved Raman scattering, which reveals laser-field dependent\nmode splitting and enhanced lifetimes. We expect this phenomenon to be\ngenerally observable in many materials systems, affecting the non-equilibrium\nemergent phases in matter."
    },
    {
        "anchor": "Nanoscale Surface Analysis on Second Generation Advanced High Strength\n  Steel after Hot Dip Galvanizing: Second Generation advanced high strength steel is the material of choice for\nmodern automotive structural parts because of its outstanding maximal\nelongation and tensile strength. Nonetheless there is still a lack of corrosion\nprotection for this material due to the fact that cost efficient hot dip\ngalvanizing can not be applied. The reason for the insufficient coatability\nwith zinc is found in the segregation of manganese to the surface during\nannealing and the formation of manganese oxides prior coating. This work\nanalyses the structure and chemical composition of the surface oxides on so\ncalled nano-TWIP (twinning induced plasticity) steel on the nanoscopic scale\nafter hot dip galvanizing in a simulator with employed analytical methods\ncomprising scanning Auger electron spectroscopy (SAES), energy dispersive x-ray\nspectroscopy (EDX), and focused ion beam (FIB) for cross section preparation.\nBy the combination of these methods it was possible to obtain detailed chemical\nimages serving a better understanding which processes exactly occur on the\nsurface of this novel kind of steel and how to promote in the future for this\nmaterial system galvanic protection.",
        "positive": "Coexistence of Tunable Weyl Points and Topological Nodal Lines in\n  Ternary Transition-Metal Telluride TaIrTe4: We report a combined theoretical and experimental study on TaIrTe4, a\npotential candidate of the minimal model of type-II Weyl semimetals.\nUnexpectedly, an intriguing node structure with twelve Weyl points and a pair\nof nodal lines protected by mirror symmetry was found by first-principle\ncalculations, with its complex signatures such as the topologically non-trivial\nband crossings and topologically trivial Fermi arcs cross-validated by\nangle-resolved photoemission spectroscopy. Through external strain, the number\nof Weyl points can be reduced to the theoretical minimum of four, and the\nappearance of the nodal lines can be switched between different mirror planes\nin momentum space. The coexistence of tunable Weyl points and nodal lines\nestablishes ternary transition-metal tellurides as a unique test ground for\ntopological state characterization and engineering."
    },
    {
        "anchor": "Frequency-dependent dielectric function of semiconductors with\n  application to physisorption: The dielectric function is one of the most important quantities that\ndescribes the electrical and optical properties of solids. Accurate modeling of\nthe frequency-dependent dielectric function has great significance in the study\nof the long-range van der Waals (vdW) interaction for solids and adsorption. In\nthis work, we calculate the frequency-dependent dielectric functions of\nsemiconductors and insulators using the $GW$ method with and without exciton\neffects, as well as efficient semilocal density functional theory (DFT), and\ncompare these calculations with a model frequency-dependent dielectric\nfunction. We find that for semiconductors with moderate band gaps, the model\ndielectric functions, $GW$ values, and DFT calculations all agree well with\neach other. However, for insulators with strong exciton effects, the model\ndielectric functions have a better agreement with accurate $GW$ values than the\nDFT calculations, particularly in high-frequency region. To understand this, we\nrepeat the DFT calculations with scissors correction, by shifting DFT Kohn-Sham\nenergy gap to match the experimental band gap. We find that scissors correction\nonly moderately improves the DFT dielectric function in low-frequency region.\nBased on the dielectric functions calculated with different methods, we make a\ncomparative study by applying these dielectric functions to calculate the vdW\ncoefficients ($C_3$ and $C_5$) for adsorption of rare-gas atoms on a variety of\nsurfaces. We find that the vdW coefficients obtained with the nearly-free\nelectron gas-based model dielectric function agree quite well with those\nobtained from the $GW$ dielectric function, in particular for adsorption on\nsemiconductors, leading to an overall error of less than 7% for $C_3$ and 5%\nfor $C_5$. This demonstrates the reliability of the model dielectric function\nfor the study of physisorption.",
        "positive": "Thermoelectric power factor of Bi-Sb-Te and Bi-Te-Se alloys and doping\n  strategy: First-principles study: By performing first principles calculations combined with Boltzmann transport\nequations, we calculate the thermoelectric power factor (PF) of Bi-Sb-Te and\nBi-Te-Se ternary alloys as a function of alloy composition ratio, carrier\nconcentration, and temperature. The point defect formation energy calculations\nalso perform to search potential n-type dopant candidates in ternaries."
    },
    {
        "anchor": "Long-Range Magnetic Exchange Pathways in Complex Clusters from\n  First-Principles: This work builds a bridge between density functional theory (DFT) and model\ninterpretations of Anderson's superexchange theory by constructing a\n$f$-$d$-$p$ model with DFT Wannier functions to enable a direct quantum\nmany-body solution within an embedding approach. When applied to long-range\nmagnetic interactions in a Mn-Ce magnetic molecule, we are able to obtain\nnumerical insights about double exchange and superexchange interactions. Direct\nmetal-metal charge transfer processes are generally weak in this molecule,\nwhich leads to small contributions from double exchange interactions. For\nlong-range interactions, Mn-Ce charge transfer is not significant compared to\nCe-O charge transfer. The unusual superexchange between Mn atoms with different\nvalence states is identified as the dominant mechanism. This procedure opens a\npath for quantitative understanding of different exchange interactions in\ncomplex magnetic systems, including molecular magnets, transition metal organic\nframeworks, and other solid materials.",
        "positive": "Structural properties of TaAs Weyl semimetal thin films grown by\n  molecular beam epitaxy on GaAs(001) substrates: Thin crystalline layers of TaAs Weyl semimetal (9 and 18 nm thick) are grown\nby molecular beam epitaxy on GaAs(001) substrates. The (001) planes of the\ntetragonal TaAs lattice are parallel to the GaAs(001) substrate, but the\ncorresponding in-plane crystallographic directions of the substrate and the\nlayer are rotated by 45{\\deg}. In spite of a substantial lattice mismatch\n(about 19%) between GaAs(001) substrate and TaAs epilayer no misfit\ndislocations are observed at the GaAs(001)/TaAs(001) interface. Only stacking\nfault defects in TaAs are detected with transmission electron microscopy.\nThorough X-ray diffraction measurements and analysis of the in-situ reflection\nhigh energy electron diffraction images indicates that TaAs layers are fully\nrelaxed already at the initial deposition stage. Atomic force microscopy\nimaging reveals the columnar structure of the layers, with lateral (parallel to\nthe layer surface) columns about 20 nm wide and 200 nm long. Both X-ray\ndiffraction and transmission electron microscopy measurements indicate that the\ncolumns share the same orientation and crystalline structure."
    },
    {
        "anchor": "Selective enhancement of coherent optical phonons using THz-rate pulse\n  train: Selective enhancement of coherent optical phonons in Bi-Sb mixed crystals has\nbeen performed using terahertz (THz) rate pulse trains generated by spatial\nphase modulation of femtosecond pulse with a liquid-crystal spatial light\nmodulator. The profile of the shaped pulse train has a flat-toped shape. The\nBi-Bi, Bi-Sb, and Sb-Sb vibrations can be enhanced and canceled selectively for\npulse trains with a suitable repetition rate.",
        "positive": "Extremal collision sequences of particles on a line: optimal\n  transmission of kinetic energy: The transmission of kinetic energy through chains of inelastically colliding\nspheres is investigated for the case of constant coefficient of restitution\n\\epsilon=const and impact-velocity dependent coefficient \\epsilon(v) for\nviscoelastic particles. We derive a theory for the optimal distribution of\nparticle masses which maximize the energy transfer along the chain and check it\nnumerically. We found that for \\epsilon=const the mass distribution is a\nmonotonous function which does not depend on the value of \\epsilon. In\ncontrast, for \\epsilon(v) the mass distribution reveals a pronounced maximum,\ndepending on the particle properties and on the chain length. The system\ninvestigated demonstrates that even for small and simple systems the velocity\ndependence of the coefficient of restitution may lead to new effects with\nrespect to the same systems under the simplifying approximation \\epsilon=const."
    },
    {
        "anchor": "A non-singular continuum theory of point defects using gradient\n  elasticity of bi-Helmholtz type: In this paper, we develop a non-singular continuum theory of point defects\nbased on a second strain gradient elasticity theory, the so-called gradient\nelasticity of bi-Helmholtz type. Such a generalized continuum theory possesses\na weak nonlocal character with two internal material lengths and provides a\nmechanics of defects without singularities. Gradient elasticity of bi-Helmholtz\ntype gives a natural and physical regularization of the classical singularities\nof defects, based on higher order partial differential equations. Point defects\nembedded in an isotropic solid are considered as eigenstrain problem in\ngradient elasticity of bi-Helmholtz type. Singularity-free fields of point\ndefects are presented. The displacement field as well as the first, the second\nand the third gradients of the displacement are derived and it is shown that\nthe classical singularities are regularized in this framework. This model\ndelivers non-singular expressions for the displacement field, the first\ndisplacement gradient and the second displacement gradient. Moreover, the\nplastic distortion (eigendistortion) and the gradient of the plastic distortion\nof a dilatation centre are also non-singular and are given in terms of a form\nfactor (shape function) of a point defect. Singularity-free expressions for the\ninteraction energy and the interaction force between two dilatation centres and\nfor the interaction energy and the interaction force of a dilatation centre in\nthe stress field of an edge dislocation are given. The results are applied to\ncalculate the finite self-energy of a dilatation centre.",
        "positive": "Tunable mechanical properties of the graphene/MoS2 tubal van der Waals\n  heterostructure: We propose a tubal van der Waals heterostructure by rolling up the graphene\nand MoS2 atomic layers into a tubal form. We illustrate that the interlayer\nspace for the tubal van der Waals heterostructure can be varied in a specific\nrange, which is determined by the competition between the interlayer van der\nWaals force and the mechanical properties of the atomic layers. The variability\nof the interlayer space can be utilized to efficiently tune mechanical\nproperties of the tubal van der Waals heterostructure. More specifically, we\ndemonstrate that the Poisson's ratio of the tubal van der Waals heterostructure\ncan be manipulated by a factor of two by varying the interlayer space from 1.44\nto 4.44. Our work promotes a new member with tunable Poisson's ratio to the van\nder Waals heterostructure family."
    },
    {
        "anchor": "Tracking single atoms in a liquid environment: The chemical behaviour of single metal atoms largely depends on the local\ncoordination environment, including interactions with the substrate and with\nthe surrounding gas or liquid. However, the key instrumentation for studying\nsuch systems at the atomic scale generally requires high vacuum conditions,\nlimiting the degree to which the aforementioned environmental parameters can be\ninvestigated. Here we develop a new platform for transmission electron\nmicroscopy investigation of single metal atoms in liquids and study the dynamic\nbehaviour of individual platinum atoms on the surface of a single layer MoS2\ncrystal in water. To achieve the record single atom resolution, we introduce a\ndouble liquid cell based on a 2D material heterostructure, which allows us to\nsubmerge an atomically thin membrane with liquid on both sides while\nmaintaining the total specimen thickness of only ~ 70 nm. By comparison with an\nidentical specimen imaged under high vacuum conditions, we reveal drastic\ndifferences in the single atom resting sites and atomic hopping behaviour,\ndemonstrating that in situ imaging conditions are essential to gain complete\nunderstanding of the chemical activity of individual atoms. These findings pave\nthe way for in situ liquid imaging of chemical processes with single atom\nprecision.",
        "positive": "Method for Identifying Crystalline Phases in X-ray Diffraction Data from\n  Multiphase Samples: A new method for identifying crystalline phases in X-ray diffraction data has\nbeen proposed, which is especially useful for the study of multiphase materials\n(more than eight - ten phases) with a relatively low content (less than 1 - 3\nwt\\%). The method is based on a statistical analysis of data and provides an\nunambiguous non-quantitative criterion for the presence of one or another phase\nin the material. It has been shown that the method works reliably in cases\nwhere a significant number of reflexes (more than several dozen) on the\ndiffraction pattern are comparable with intensity-to-noise ratio."
    },
    {
        "anchor": "FPEOS: A First-Principles Equation of State Table of Deuterium for\n  Inertial Confinement Fusion Applications: Understanding and designing inertial confinement fusion (ICF) implosions\nthrough radiation-hydrodynamics simulations rely on the accurate knowledge of\nthe equation of state (EOS) of the deuterium and tritium fuels. To minimize the\ndrive energy for ignition, the imploding shell of DT fuel must be kept as cold\nas possible. Such low-adiabat ICF implosions can access to coupled and\ndegenerate plasma conditions, in which the analytical or chemical EOS models\nbecome inaccurate. Using the path-integral Monte Carlo (PIMC) simulations we\nhave derived a first-principles EOS (FPEOS) table of deuterium that covers\ntypical ICF fuel conditions at densities ranging from 0.002 to 1596 g/cm3 and\ntemperatures of 1.35 eV to 5.5 keV. We report the internal energy and the\npressure, and discuss the structure of the plasma in terms of pair-correlation\nfunctions. When compared with the widely used SESAME table and the revised\nKerley03 table, discrepancies in the internal energy and in the pressure are\nidentified for moderately coupled and degenerate plasma conditions. In contrast\nto the SESAME table, the revised Kerley03 table is in better agreement with our\nFPEOS results over a wide range of densities and temperatures. Although subtle\ndifferences still exist for lower temperatures (T < 10 eV) and moderate\ndensities (1 to 10 g/cc), hydrodynamics simulations of cryogenic ICF implosions\nusing the FPEOS table and the Kerley03 table have resulted in similar results\nfor the peak density, areal density ({\\rho}R), and neutron yield, which are\nsignificantly different from the SESAME simulations.",
        "positive": "Kinetic energy density functionals from the Airy gas, with an\n  application to the atomization kinetic energies of molecules: We construct and study several semilocal density functional approximations\nfor the positive Kohn-Sham kinetic energy density. These functionals fit the\nkinetic energy density of the Airy gas and they can be accurate for integrated\nkinetic energies of atoms, molecules, jellium clusters and jellium surfaces. We\nfind that these functionals are the most accurate ones for atomization kinetic\nenergies of molecules and for fragmentation of jellium clusters. We also report\nthat local and semilocal kinetic energy functionals can show \"binding\" when the\ndensity of a spin unrestricted Kohn-Sham calculation is used."
    },
    {
        "anchor": "Substitutional nickel impurities in diamond: decoherence-free subspaces\n  for quantum information processing: The electronic and magnetic properties of a neutral substitutional nickel\n(Ni$_s^0$) impurity in diamond are studied using density functional theory in\nthe generalized gradient approximation. The spin-one ground state consists of\ntwo electrons with parallel spins, one located on the nickel ion in the $3d^9$\nconfiguration and the other distributed among the nearest-neighbor carbons. The\nexchange interaction between these spins is due to $p-d$ hybridization and is\ncontrollable with compressive hydrostatic or uniaxial strain, and for\nsufficient strain the antiparallel spin configuration becomes the ground state.\nHence, the Ni impurity forms a controllable two-electron exchange-coupled\nsystem that should be a robust qubit for solid-state quantum information\nprocessing.",
        "positive": "Giant thermopower and figure of merit in single-molecule devices: We present a study of the thermopower $S$ and the dimensionless figure of\nmerit $ZT$ in molecules sandwiched between gold electrodes. We show that for\nmolecules with side groups, the shape of the transmission coefficient can be\ndramatically modified by Fano resonances near the Fermi energy, which can be\ntuned to produce huge increases in $S$ and $ZT$. This shows that molecules\nexhibiting Fano resonances have a high efficiency of thermoelectric cooling\nwhich is not present for conventional un-gated molecules with only delocalized\nstates along their backbone."
    },
    {
        "anchor": "Quantum Prediction of Ultra-Low Thermal Conductivity in Lithium\n  Intercalation Materials: Lithium-intercalated layered transition-metal oxides, LixTMO2, brought about\na paradigm change in rechargeable batteries in recent decades and show promise\nfor use in memristors, a type of device for future neural computing and on-chip\nstorage. Thermal transport properties, although being a crucial element in\nlimiting the charging/discharging rate, package density, energy efficiency, and\nsafety of batteries as well as the controllability and energy consumption of\nmemristors, are poorly managed or even understood yet. Here, for the first\ntime, we employ quantum calculations including high-order lattice anharmonicity\nand find that the thermal conductivity k of LixTMO2 materials is significantly\nlower than hitherto believed. More specifically, the theoretical upper limit of\nk of LiCoO2 is 6 W/m-K, 2-6 times lower than the prior theoretical predictions.\nDelithiation further reduces k by 40-70% for LiCoO2 and LiNbO2. Grain\nboundaries, strains, and porosity are yet additional causes of\nthermal-conductivity reduction, while Li-ion diffusion and electrical transport\nare found to have only a minor effect on phonon thermal transport. The results\nelucidate several long-standing issues regarding the thermal transport in\nlithium-intercalated materials and provide guidance toward designing\nhigh-energy-density batteries and controllable memristors.",
        "positive": "Three terminal capacitance technique for magnetostriction and thermal\n  expansion measurements: An instrument has been constructed to measure a large range of\nmagnetostriction and thermal expansion between room temperature and 4 K in a\nsuperconductive split-coil magnet, that allows investigation in magnetic fields\nup to 12 T. The very small bulk samples (up to 1 mm in size) as well as big\nones (up to 13 mm) of the irregular form can be measured. The possibility of\nmagnetostriction investigation in thin films is shown. A general account is\ngiven of both electrical and the mechanical aspects of the design of\ncapacitance cell and their associated electronic circuitry. A simple lever\ndevice is proposed to increase the sensitivity twice. The resulting obtained\nsensitivity can be 0.5 Angstrom. The performance of the technique is\nillustrated by some preliminary measurements of the magnetostriction of\nsuperconducting MgB2, thermal expansion of (La0.8Ba0.2)0.93MnO3 single crystal\nand magnetoelastic behavior of the Ni/Si(111) and\nLa0.7Sr0.3CoO3/SAT0.7CAT0.1LA0.2(001) cantilevers."
    },
    {
        "anchor": "A combinatorial approach for studying the effect of Mg concentration on\n  precipitation in an Al-Cu-Li alloy: We apply a combinatorial approach to study the influence of Mg concentration\non the precipitation kinetics in an Al-Cu-Li alloy using a diffusion couple\nmade by linear friction welding. The precipitation kinetics is monitored in the\ncomposition gradient material using simultaneous space and time-resolved\nin-situ small-angle X-ray scattering measurements during ageing, and the\nstrengthening of the precipitates is evaluated by micro-hardness profiles. This\ndata provides an evaluation of the amount of Mg necessary to promote\nprecipitation of the T1-Al2CuLi phase.",
        "positive": "A Molecular Dynamics Study of Self-Diffusion in Stoichiometric B2-NiAl\n  crystals: Self-diffusion parameters in stoichiometric B2-NiAl solid state crystals were\nestimated by molecular statics/dynamics simulations with the study of required\nsimulation time to stabilise diffusivity results. An extrapolation procedure to\nimprove the diffusion simulation results was proposed. Calculations of volume\ndiffusivity for the B2 type NiAl in the 1224 K to 1699 K temperature range were\nperformed using the embedded atom model potential. The results obtained here\nare in much better agreement with the experimental results than the theoretical\nestimates obtained with other methods."
    },
    {
        "anchor": "A novel concept of pseudo ternary diffusion couple for the estimation of\n  diffusion coefficients in multicomponent systems: A pseudo ternary diffusion couple technique in a multicomponent system by\nsimplifying the mathematical complications of Onsager formalism is proposed for\nthe estimation of composition dependent values of the interdiffusion\ncoefficients. This is otherwise impossible following the conventional method in\na system with more than three components. Other alternative methods estimate\nthe average diffusion coefficients over a composition range of random choice\nand lack physical significance. This method can be followed in a multicomponent\nsystem with any number of components on the condition that only three\ncomponents develop diffusion profiles keeping others as constant.",
        "positive": "Effective structural unit analysis in hexagonal close packed alloys --\n  reconstruction of parent beta microstructures & crystal orientation post\n  processing analysis: Materials with an allotropic phase transformation can result in the formation\nof microstructures where grains have orientation relationships (ORs) determined\nby the transformation history. These microstructures influence the final\nmaterial properties. In zirconium alloys, there is a solid-state body centred\ncubic (BCC) to hexagonal close packed (HCP) phase transformation, where the\ncrystal orientations of the HCP phase can be related to the parent BCC\nstructure via the Burgers orientation relationship (BOR). In the present work,\nwe adapt a reconstruction code developed for steels which uses a Markov Chain\nclustering algorithm to analyse electron backscatter diffraction (EBSD) maps\nand apply this to the HCP and BCC BOR. This algorithm is released as\nopen-source code (via github, as ParentBOR). The algorithm enables new post\nprocessing of the original and reconstructed data set to analyse the variants\nof the HCP alpha-phase that are present and understand shared crystal planes\nand shared lattice directions within each parent beta grain, and we anticipate\nthat this assists in understanding the transformation related deformation\nproperties of the final microstructure. Finally, we compare the ParentBOR code\nwith recently released reconstruction codes implemented in MTEX to reveal\ndifferences and similarities in how the microstructure is described."
    },
    {
        "anchor": "Large-Area Aiming Synthesis of WSe2 Monolayers: The monolayer transition metal dichalcogenides have recently attracted much\nattention owing to their potential in valleytronics, flexible and low-power\nelectronics and optoelectronic devices. Recent reports have demonstrated the\ngrowth of large-size 2-dimensional MoS2 layers by the sulfurization of\nmolybdenum oxides. However, the growth of transition metal selenide monolayer\nhas still been a challenge. Here we report that the introduction of hydrogen in\nthe reaction chamber helps to activate the selenization of WO3, where\nlarge-size WSe2 monolayer flakes or thin films can be successfully grown.",
        "positive": "GaN/AlN Quantum Dots for Single Qubit Emitters: We study theoretically the electronic properties of $c$-plane GaN/AlN quantum\ndots (QDs) with focus on their potential as sources of single polarized photons\nfor future quantum communication systems. Within the framework of eight-band\nk.p theory we calculate the optical interband transitions of the QDs and their\npolarization properties. We show that an anisotropy of the QD confinement\npotential in the basal plane (e.g. QD elongation or strain anisotropy) leads to\na pronounced linear polarization of the ground state and excited state\ntransitions. An externally applied uniaxial stress can be used to either induce\na linear polarization of the ground-state transition for emission of single\npolarized photons or even to compensate the polarization induced by the\nstructural elongation."
    },
    {
        "anchor": "Exciton-phonon interaction in the strong coupling regime in hexagonal\n  boron nitride: The temperature-dependent optical response of excitons in semiconductors is\ncontrolled by the exciton-phonon interaction. When the exciton-lattice coupling\nis weak, the excitonic line has a Lorentzian profile resulting from motional\nnarrowing, with a width increasing linearly with the lattice temperature $T$.\nIn contrast, when the exciton-lattice coupling is strong, the lineshape is\nGaussian with a width increasing sublinearly with the lattice temperature,\nproportional to $\\sqrt{T}$. While the former case is commonly reported in the\nliterature, here the latter is reported for the first time, for hexagonal boron\nnitride. Thus the theoretical predictions of Toyozawa [Progr. Theor. Phys. 20,\n53 (1958)] are supported by demonstrating that the exciton-phonon interaction\nis in the strong coupling regime in this Van der Waals crystal.",
        "positive": "Laser induced surface magnetization in Floquet-Weyl semimetals: We investigate optically induced magnetization in Floquet-Weyl semimetals\ngenerated by irradiation of a circularly-polarized continuous-wave laser from\nthe group II-V narrow gap semiconductor Zn$_3$As$_2$ in a theoretical manner.\nHere, this trivial and nonmagnetic crystal is driven by the laser with a nearly\nresonant frequency with a band gap to generate two types of Floquet-Weyl\nsemimetal phases composed of different spin states. These two phases host\nnontrivial two-dimensional surface states pinned to the respective pairs of the\nWeyl points. By numerically evaluating the laser-induced transient\ncarrier-dynamics, it is found that both spins are distributed in an uneven\nmanner on the corresponding surface states due to significantly different\nexcitation probabilities caused by the circularly-polarized laser with the\nnearly resonant frequency. It is likely that such spin-polarized surface states\nproduce surface magnetization, and furthermore the inverse Faraday effect also\ncontributes almost as much as the spin magnetization. To be more specific,\nexcited carries with high density of the order of $10^{21}\\: {\\rm cm}^{-3}$ are\ngenerated by the laser with electric field strength of a few MV/cm to result in\nthe surface magnetization that becomes asymptotically constant with respect to\ntime, around 1 mT. The magnitude and the direction of it depend sharply on both\nof the intensity and frequency of the driving laser, which would be detected by\nvirtue of the magneto-optic Kerr effect."
    },
    {
        "anchor": "Effect of doping of zinc oxide on the hole mobility of\n  poly(3-hexylthiophene) in hybrid transistors: Hybrid field effect transistors based on the organic polymer\npoly(3-hexylthiophene) (P3HT) and inorganic zinc oxide were investigated. In\nthis report we present one of the first studies on hybrid transistors employing\none polymeric transport layer. The sol-gel processed ZnO was modified via Al\ndoping between 0.8 and 10 at.%, which allows a systematic variation of the zinc\noxide properties, i.e. electron mobility and morphology. With increasing doping\nlevel we observe on the one hand a decrease of the electron mobilities by two\norders of magnitude,on the other hand doping enforces a morphological change of\nthe zinc oxide layer which enables the infiltration of P3HT into the inorganic\nmatrix. X-ray reflectivity (XRR) measurements confirm this significant change\nin the interface morphology for the various doping levels. We demonstrate that\ndoping of ZnO is a tool to adjust the charge transport in ZnO/P3HT hybrids,\nusing one single injecting metal (Au bottom contact) on a SiO2 dielectric. We\nobserve an influence of the zinc oxide layer on the hole mobility in P3HT which\nwe can modify via Al doping of ZnO. Hence, maximum hole mobility of 5e-4\ncm^2/Vs in the hybrid system with 2 at.% Al doping. 5 at.% Al doping leads to a\nbalanced mobility in the organic/inorganic hybrid system but also to a small\non/off ratio due to high off-currents.",
        "positive": "Reorganization energy from charge transport measurements in a\n  monolithically$-$integrated molecular device: Intermolecular charge transfer reactions are key processes in physical\nchemistry. The electron-transfer rates depend on a few system's parameters,\nsuch as temperature, electromagnetic field, distance between adsorbates and,\nespecially, the molecular reorganization energy. This microscopic greatness is\nthe energetic cost to rearrange each single$-$molecule and its surrounding\nenvironment when a charge is transferred. Reorganization energies are measured\nby electrochemistry and spectroscopy techniques as well as at the\nsingle-molecule limit using atomic force microscopy approaches, but not from\ntemperature$-$dependent charge transport measurements nor in a\nmonolithically$-$integrated molecular device. Nowadays self$-$rolling\nnanomembrane (rNM) devices, with strain$-$engineered mechanical properties,\non$-$a$-$chip monolithic integration, and operable in distinct environments,\novercome those challenges. Here, we investigate the charge transfer reactions\noccurring within a ca. 6 nm thick copper$-$phthalocyanine (CuPc) film employed\nas electrode-spacer in a monolithically integrated nanocapacitor. Employing the\nrNM technology allows us to measure the molecules' charge$-$transport\ndependence on temperature for different electric fields. Thereby, the CuPc\nreorganization energy is determined as (930 $\\pm$ 40) meV, whereas density\nfunctional theory (DFT) calculations support our findings with the atomistic\npicture of the CuPc charge transfer reaction. Our approach presents a\nconsistent route towards electron transfer reaction characterization using\ncurrent$-$voltage spectroscopy and provides insight into the role of the\nmolecular reorganization energy when it comes to electrochemical nanodevices."
    },
    {
        "anchor": "Hydrogen dissociation catalyzed by carbon coated nickel nanoparticles:\n  experiment and theory: Based on combination of experimental measurements and first-principles\ncalculations we report a novel carbon-based catalytic material and describe\nsignificant acceleration of the hydrogenation of magnesium at room temperature\nin presence of nickel nanoparticles wrapped in multilayer graphene. Increase of\nthe rate of magnesium hydrogenation in contrast to the mix of graphite and\nnickel nanoparticles evidences intrinsic catalytic properties of explored\nnanocomposites. Results of simulations demonstrate that the doping from metal\nsubstrate and the presence of Stone-Wales defects turn multilayer graphene from\nchemically inert to chemically active mode. The role of the size of\nnanoparticles and temperature are also discussed.",
        "positive": "Nanoscale clusters in the high performance thermoelectric AgPbmSbTem+2: The local structure of the AgPbmSbTem+2 series of thermoelectric materials\nhas been studied using the atomic pair distribution function (PDF) method.\nThree candidate-models were attempted for the structure of this class of\nmaterials using either a one-phase or a two-phase modeling procedure. Combining\nmodeling the PDF with HRTEM data we show that AgPbmSbTem+2 contains nanoscale\ninclusions with composition close to AgPb3SbTe5 randomly embedded in a PbTe\nmatrix."
    },
    {
        "anchor": "Defect thermodynamics and kinetics in thin strained ferroelectric films:\n  the interplay of possible mechanisms: We present a theoretical description of the influence of misfit strain on\nmobile defects dynamics in thin strained ferroelectric films. Self-consistent\nsolutions obtained by coupling the Poissons equation for electric potential\nwith continuity equations for mobile donor and electron concentrations and\ntime-dependent Landau-Ginzburg-Devonshire equations reveal that the Vegard\nmechanism (chemical pressure) leads to the redistribution of both charged and\nelectro-neutral defects in order to decrease the effective stress in the film.\nInternal electric fields, both built-in and depolarization ones, lead to a\nstrong accumulation of screening space charges (charged defects and electrons)\nnear the film interfaces. Importantly, the corresponding screening length is\ngoverned by the misfit strain and Vegard coefficient. Mobile defects dynamics,\nkinetics of polarization and electric current reversal are defined by the\ncomplex interplay between the donor, electron and phonon relaxation times,\nmisfit strain, finite size effect and Vegard stresses.",
        "positive": "Self-repairing high entropy oxides: All biological organisms, from plants to living creatures, can heal minor\nwounds and damage. The realization of a similar self-healing capacity in\ninorganic materials has been a design target for many decades. This would\nrepresent a breakthrough in materials engineering, enabling many novel\ntechnological applications, since such materials would be able to resist damage\ncaused by electromagnetic irradiation and/or mechanical impact. Here we\ndemonstrate that a high-entropy oxide is intrinsically capable of undergoing an\nautonomous self-repairing process. Transmission electron microscopy revealed\nthat the spinel structure of (AlCoCrCu0.5FeNi)3O4 can regrow and repair itself\nat the atomic level when damaged. Density functional theory calculations reveal\nthat the extra enthalpy stored in the high entropy material during fabrication\ncan be released to effectively heal macroscopic defects by regrowing into a\npartially ordered state. This extraordinary self-repairing phenomenon makes\nthis new material highly desirable as a coating, enabling structures used in\nharsh environments to better withstand damage, such as cosmic irradiation in\nspace, nuclear irradiation in nuclear power facilities, or tribological damage.\nMost importantly, our results set the general design principles for the\nsynthesis of self-repairing materials."
    },
    {
        "anchor": "Observation of Dirac-like band dispersion in LaAgSb$_2$: We present a combined angle-resolved photoemission spectroscopy (ARPES) and\nfirst-principles calculations study of the electronic structure of LaAgSb$_2$\nin the entire first Brillouin zone. We observe a Dirac-cone-like structure in\nthe vicinity of the Fermi level formed by the crossing of two linear energy\nbands, as well as the nested segments of Fermi surface pocket emerging from the\ncone. Our ARPES results show the close relationship of the Dirac cone to the\ncharge-density-wave ordering, providing consistent explanations for exotic\nbehaviors in this material.",
        "positive": "Copper ion dynamics and phase segregation in Cu-rich tetrahedrite: an\n  NMR study: $^{63}$Cu NMR measurements are reported for the Cu-rich phase of\n\\ch{Cu_{12+x}Sb4S13} ($x \\lesssim 2$) and compared to \\ch{Cu12Sb4S13}. We\nidentify the NMR signatures of the phase segregation into Cu-poor ($x \\approx\n0$) and Cu-rich ($x \\lesssim 2$) phases, with the metal-insulator transition\nobserved in \\ch{Cu12Sb4S13} suppressed in the Cu-rich phase. Based on NMR $T_1$\nand $T_2$ measurements, the results demonstrate Cu-ion hopping below room\ntemperature with an activation energy of $\\sim$150 meV for the Cu-rich phase,\nconsistent with superionic behavior. The NMR results also demonstrate the\neffects of Cu-ion mobility in the \\ch{Cu12Sb4S13} phase, but with a larger\nactivation barrier. We identify a small difference in NMR Knight shift for the\nmetallic phase of \\ch{Cu12Sb4S13}, compared to the Cu-rich phase, and when\ncompared to DFT calculations the results indicate a mix of hyperfine\ncontributions to the metallic shift."
    },
    {
        "anchor": "Magnon mediated spin pumping by coupled ferrimagnetic garnets\n  heterostructure: Spin pumping has significant implications for spintronics, providing a\nmechanism to manipulate and transport spins for information processing.\nUnderstanding and harnessing spin currents through spin pumping is critical for\nthe development of efficient spintronic devices. The use of a magnetic\ninsulator with low damping, enhances the signal-to-noise ratio in crucial\nexperiments such as spin-torque ferromagnetic resonance (FMR) and spin pumping.\nA magnetic insulator coupled with a heavy metal or quantum material offers a\nmore straight forward model system, especially when investigating spin-charge\ninterconversion processes to greater accuracy. This simplicity arises from the\nabsence of unwanted effects caused by conduction electrons unlike in\nferromagnetic metals. Here, we investigate the spin pumping in coupled\nferrimagnetic (FiM) Y3Fe5O12 (YIG)/Tm3Fe5O12 (TmIG) bilayers combined with\nheavy-metal (Pt) using the inverse spin Hall effect (ISHE). It is observed that\nmagnon transmission occurs at both of the FiMs FMR positions. The enhancement\nof spin pumping voltage (Vsp) in the FiM garnet heterostructures is attributed\nto the strong interfacial exchange coupling between FiMs. The modulation of Vsp\nis achieved by tuning the bilayer structure. Further, the spin mixing\nconductance for these coupled systems is found to be 10^18 m^-2. Our findings\ndescribe a novel coupled FiM system for the investigation of magnon coupling\nproviding new prospects for magnonic devices.",
        "positive": "Aluminum functionalized silicene: a potential anode material for alkali\n  metal ion batteries: We have investigated the possibility of using aluminum functionalized\nsilicene trilayers (ABC-Si$_4$Al$_2$) as an anode material for alkali metal ion\nbatteries (AMIBs). First, we studied the thermodynamic stability of\nABC-Si$_4$Al$_2$ using ab-initio molecular dynamics simulations, showing that\nthis material remains stable up to 600 K. Then, we explored the properties of\nalkali metal atoms (Li, Na, K) adsorption in ABC-Si$_4$Al$_2$, finding several\navailable sites with high adsorption energies. Moreover, we computed the\ndiffusion properties of those atoms along high-symmetry paths using the nudged\nelastic band method. The results indicated diffusion barriers as low as those\nin graphite, especially for Na (0.32 eV) and K (0.22 eV), which allows those\nions to migrate easily on the material's surface. Our studies also revealed\nthat the full loaded Li$_4$Si$_4$Al$_2$, Na$_2$Si$_4$Al$_2$, and\nK$_2$Si$_4$Al$_2$ systems provide low open-circuit voltage, ranging from 0.14\nto 0.49 V, and large theoretical capacity of 645 mAh/g for Li- and 322 mAh/g\nfor Na- and K-ion batteries, values that are close to the ones in other anode\nmaterials, such as graphite, TiO$_2$, and silicene-based systems. Those results\nindicate that aluminum functionalized few-layer silicene is a promising\nmaterial for AMIBs anodes, particularly for Na- and K-ion batteries."
    },
    {
        "anchor": "Elastic properties of superconducting LiFeAs from first principles: The first-principles FLAPW-GGA calculations of the elastic properties of\nrecently discovered superconducting LiFeAs are reported. The independent\nelastic constants (Cij), bulk modulus, compressibility, and shear modulus are\nevaluated and discussed. Additionally, numerical estimates of the elastic\nparameters of the polycrystalline LiFeAs ceramics are performed for the first\ntime.",
        "positive": "XPS Supported INS and DRIFT Spectroscopy of sp2 Amorphous Carbons: We carried out a joint analysis of the INS, DRIFT, and XPS spectra of a set\nof sp2 amorphous carbons of the highest carbonization rank representing natural\nsubstances (shungite carbon, anthraxolite, and anthracite), technical graphenes\n(laboratory reduced graphene oxides), and industrial products (carbon blacks).\nIt was determined, that the DRIFT spectra of the studied substances consist of\ntwo components determined by hydrogen and oxygen compositions in the\ncircumference of graphene molecules, which represent the basic structural units\nof amorphic compounds. Methine groups typify the hydrogen component of natural\namorphics while hydroxymethyls and methyls do the same job for the studied\ntechnical graphenes and hydroxyfurans for carbon blacks. A particular\nspecificity of the methine-based hydrogen compositions to enhance electrooptic\ncharacteristics of the DRIFT spectrum of carbon atoms has been established. A\ncomparable analysis of DRIFT and XPS spectra has allowed a reliable\npersonification of the oxygen functional groups compositions of the studied\namorphics resulting in a set of dependable molecular models of their basic\nstructural units."
    },
    {
        "anchor": "Ab initio quantum transport in AB-stacked bilayer penta-silicene using\n  atomic orbitals: The current carried by a material subject to an electric field is\nmicroscopically inhomogeneous and can be modelled using scattering theory, in\nwhich electrons undergo collisions with the microscopic objects they encounter.\nWe herein present a methodology for parameter-free calculations of the current\ndensity from first-principles using Density Functional Theory, Wannier\nfunctions and scattering matrices. The methodology is used on free-standing\nAB-stacked bilayer penta-silicene. This new Si allotrope has been proposed to\nhave a higher stability than any of its hexagonal bilayer counterparts.\nFurthermore, its semiconducting properties make it ideal for use in electronic\ncomponents. We unveil the role of the pz orbitals in the transport through a\nthree-dimensional quantum wire and present current density streamlines that\nreveal the locations of the highest charge flow. The present methodology can be\nexpanded to accommodate many electron degrees of freedom, the application of\nelectromagnetic fields and many other physical phenomena involved in device\noperation.",
        "positive": "Ab initio approach for atomic relaxations in supported magnetic clusters: We present a newly developed scheme for atomic relaxations of magnetic\nsupported clusters. Our approach is based on the full potential\nKorringa-Kohn-Rostoker Green's function method and the second moment\ntight-binding approximation for many-body potentials. We demonstrate that only\na few iterations in ab initio calculations are necessary to find an equilibrium\nstructure of supported clusters. As an example, we present our results for\nsmall Co clusters on Cu(001). Changes in electronic and magnetic states of\nclusters due to atomic relaxations are revealed."
    },
    {
        "anchor": "Radiative damping in wave guide based FMR measured via analysis of\n  perpendicular standing spin waves in sputtered Permalloy films: The damping $\\alpha$ of the spinwave resonances in 75 nm, 120 nm, and 200nm\n-thick Permalloy films is measured via vector-network-analyzer\nferromagnetic-resonance (VNA-FMR) in the out-of-plane geometry. Inductive\ncoupling between the sample and the waveguide leads to an additional radiative\ndamping term. The radiative contribution to the over-all damping is determined\nby measuring perpendicular standing spin waves (PSSWs) in the Permalloy films,\nand the results are compared to a simple analytical model. The damping of the\nPSSWs can be fully explained by three contributions to the damping: The\nintrinsic damping, the eddy-current damping, and the radiative damping. No\nother contributions were observed. Furthermore, a method to determine the\nradiative damping in FMR measurements with a single resonance is suggested.",
        "positive": "Band-Edge Orbital Engineering of Perovskite Semiconductors for\n  Optoelectronic Applications: Lead (Pb) halide perovskites have achieved great success in recent years due\nto their excellent optoelectronic properties, which is largely attributed to\nthe lone-pair s orbital-derived antibonding states at the valence band edge.\nGuided by the key band-edge orbital character, a series of ns2-containing\n(i.e., Sn2+, Sb3+, Bi3+) Pb-free perovskite alternatives have been explored as\npotential photovoltaic candidates. On the other hand, based on the band-edge\norbital components (i.e., M2+ s and p/X- p orbitals), a series of strategies\nhave been proposed to optimize their optoelectronic properties by modifying the\natomic orbitals and orbital interactions. Therefore, understanding the\nband-edge electronic features from the recently reported halide perovskites is\nessential for future material design and device optimization. Here, this\nPerspective first attempts to establish the band-edge orbital-property\nrelationship using a chemically intuitive approach, and then rationalizes their\nsuperior properties and understands the trends in electronic properties. We\nhope that this Perspective will provide atomic-level guidance and insights\ntoward the rational design of perovskite semiconductors with outstanding\noptoelectronic properties."
    },
    {
        "anchor": "Ultra-fast relaxation of electrons in wide-gap dielectrics: Low-energy electrons scattered in the conduction band of a dielectric solid\nshould behave like Bloch electrons and will interact with perturbations of the\natomic lattice, i.e. with phonons. Thus the phonon-based description of\nlow-energy scattering within an energy band structure of a solid bears certain\nadvantages against common free-electron scattering mechanisms. Moreover, the\ninelastic scattering is described by the dielectric energy loss function. With\nthese collective scattering models we have performed the simulation of excited\nelectron relaxation and attenuation in the insulator SiO2. After excitation to\na mean initial energy of several eV their energy relaxation occurs within a\nshort time interval of 200 fs to full thermalization. There is a very rapid\nimpact ionization cooling connected with cascading of electrons at the\nbeginning during the first 10 fs, followed by much slower attenuation due to\nphonon losses in wide-gap dielectrics and insulators.",
        "positive": "Spin-orbit fields in ferromagnetic metal/semiconductor junctions: The methodology used to obtain the values of the spin-orbit couplings from\nthe spin expectation values from perturbation theory was incorrect. As a result\nFigs. 2 and 3 are incorrect."
    },
    {
        "anchor": "Observation and control of the weak topological insulator state in ZrTe5: A quantum spin Hall insulator hosts topological states at the one-dimensional\nedge, along which backscattering by nonmagnetic impurities is strictly\nprohibited and dissipationless current flows. Its 3D analogue, a weak\ntopological insulator (WTI), possesses similar quasi-1D topological states\nconfined at side surfaces of crystals. The enhanced confinement could provide a\nroute for dissipationless current and better advantages for applications\nrelative to the widely studied strong topological insulators. However, the\ntopological side surface is usually not cleavable and is thus hard to observe\nby angle-resolved photoemission spectroscopy (ARPES), which has hindered the\nrevealing of the electronic properties of WTIs. Here, we visualize the\ntopological surface states of the WTI candidate ZrTe5 for the first time by\nspin and angle-resolved photoemission spectroscopy: a quasi-1D band with\nspin-momentum locking was revealed on the side surface. We further demonstrate\nthat the bulk band gap in ZrTe5 is controlled by strain to the crystal,\nrealizing a more stabilized WTI state or an ideal Dirac semimetal state\ndepending on the direction of the external strain. The highly directional\nspin-current and the tunable band gap we found in ZrTe5 will provide an\nexcellent platform for applications.",
        "positive": "Sum-rules for electron energy-loss near-edge spectra: We derive four sum-rule expressions for spectra measured in electron\nenergy-loss near edge structure experiments. These sum-rules permit the\ndetermination spin and orbital magnetic moments, spin-orbit interaction and\nnumber of states, analogously to the sum rules of x-ray magnetic circular\ndichroism. The derivation of the sum-rules is based on dynamical electron\ndiffraction theory and the properties of the mixed dynamic form-factor. The\naccuracy of the sum-rules is tested by a complete evaluation of the thickness\ndependent electron energy-loss spectra for iron, cobalt, and nickel crystals.\nWe find that the sum-rules reproduce both spin and orbital moments with very\ngood accuracy. Our results provide a foundation for the use of the energy loss\nmagnetic chiral dichroism technique as a quantitative probe of element specific\nmagnetic properties."
    },
    {
        "anchor": "Learning phase transitions in ferrimagnetic GdFeCo alloys: We present results on the identification of phase transitions in\nferrimagnetic GdFeCo alloys using machine learning. The approach for finding\nphase transitions in the system is based on the `learning by confusion' scheme,\nwhich allows one to characterize phase transitions using a universal $W$-shape.\nBy applying the `learning by confusion' scheme, we obtain 2D $W$-a shaped\nsurface that characterizes a triple phase transition point of the GdFeCo alloy.\nWe demonstrate that our results are in the perfect agreement with the procedure\nof the numerical minimization of the thermodynamical potential, yet our\nmachine-learning-based scheme has the potential to provide a speedup in the\ntask of the phase transition identification.",
        "positive": "X-ray diffraction from dislocation half-loops in epitaxial films: X-ray diffraction from dislocation half-loops consisting of a misfit segment\nand two threading arms extending from it to the surface is calculated by the\nMonte Carlo method. The diffraction profiles and reciprocal space maps are\ncontrolled by the ratio of the total lengths of the misfit and the threading\nsegments of the half-loops. A continuous transformation from the diffraction\ncharacteristic of misfit dislocations to that of threading dislocations with\nincreasing thickness of an epitaxial film is studied. Diffraction from\ndislocations with edge and screw threading arms is considered and the\ncontributions of both types of dislocations are compared."
    },
    {
        "anchor": "Topological phases in hydrogenated gallenene and in its group elements: Nontrivial topology of Dirac (DSMs), Weyl (WSMs) and nodal line semimetals\n(NLSMs) are delineated by the novel band crossings near the Fermi level in the\nbulk and the appearance of exotic surface states. Among them, nodal line\nsemimetals have gained immense interest due to the formation of one-dimensional\nnodal ring near the Fermi level. Using density funtional theory (DFT)\ncalculations, we report that two dimensional (2D) NLSM phase can be hosted on\nhydrogen passivated (010) surface of gallium (gallenene) and on other group 13\nelements, without inclusion of spin-orbit coupling (SOC). NLSM in these 2D\nsystems is protected by the presence of crystalline (CS) along with inversion\n(IS) and the time reversal symmetry (TRS). In the presence of SOC, aluminane\npreserved its topological NLSM phase while in other single layered group 13\nelements, a gap opened at the nodal point due to relatively stronger SOC\neffect. On applying tensile strain along with the inclusion of SOC, hydrogen\npassivated gallenene (gallenane) evolves into quantum spin Hall insulator with\nan indirect bandgap of 28 meV. The appearance of long range dissipationless\nlinearly dispersive helical edge states and a large gap in gallenane make it\npromising for room temperature spintronics applications.",
        "positive": "The effect of inserted NiO layer on spin-Hall magnetoresistance in\n  Pt/NiO/YIG heterostructures: We investigate the spin-current transport through antiferromagnetic insulator\n(AFMI) by means of the spin-Hall magnetoressitance (SMR) over a wide\ntemperature range in Pt/NiO/Y$_3$Fe$_5$O$_{12}$ (Pt/NiO/YIG) heterostructures.\nBy inserting the AFMI NiO layer, the SMR dramatically decreases by decreasing\nthe temperature down to the antiferromagnetically ordered state of NiO, which\nimplies that the AFM order prevents rather than promotes the spin-current\ntransport. On the other hand, the magnetic proximity effect (MPE) on induced Pt\nmoments by YIG, which entangles with the spin-Hall effect (SHE) in Pt, can be\nefficiently screened, and pure SMR can be derived by insertion of NiO. The dual\nroles of the NiO insertion including efficiently blocking the MPE and\ntransporting the spin current from Pt to YIG are outstanding compared with\nother antiferromagnetic (AFM) metal or nonmagnetic metal (NM)."
    },
    {
        "anchor": "Atomic and molecular adsorption on transition-metal carbide (111)\n  surfaces from density-functional theory: A trend study of surface electronic\n  factors: This study explores atomic and molecular adsorption on a number of early\ntransition-metal carbides (TMC's) by means of density-functional theory\ncalculations. Trend studies are conducted with respect to both period and group\nin the periodic table, choosing the substrates ScC, TiC, VC, ZrC, NbC,\ndelta-MoC, TaC, and WC and the adsorbates H, B, C, N, O, F, NH, NH2, and NH3.\nTrends in adsorption strength are explained in terms of surface electronic\nfactors, by correlating the calculated adsorption energy values with the\ncalculated surface electronic structures. The results are rationalized with use\nof a concerted-coupling model (CCM), which has previously been applied\nsuccesfully to the description of adsorption on TiC(111) and TiN(111) surfaces\n[Solid State Commun. 141, 48 (2007)]. First, the clean TMC(111) surfaces are\ncharacterized by calculating surface energies, surface relaxations, Bader\ncharges, and surface-localized densities of states (DOS's). Detailed\ncomparisons between surface and bulk DOS's reveal the existence of\ntransition-metal localized SR's (TMSR's) in the pseudogap and of several\nC-localized SR's (CSR's) in the upper valence band on all considered TMC(111)\nsurfaces. Then, atomic and molecular adsorption energies, geometries, and\ncharge transfers are presented. An analysis of the adsorbate-induced changes in\nsurface DOS's reveals a presence of both adsorbate--TMSR and adsorbate--CSR's\ninteractions, of varying strengths depending on the surface and the adsorbate.\nThese variations are correlated to the variations in adsorption energies. The\nresults are used to generalize the content and applications of the previously\nproposed CCM to this larger class of substrates and adsorbates. Implications\nfor other classes of materials, for catalysis, and for other surface processes\nare discussed.",
        "positive": "Ab-inito study on different phases of ferromagnetic CeMnNi4: Using first-principles density functional calculations, we study the possible\nphases of CeMnNi$_{4}$ and show that the ground state is ferromagnetic. We\nobserved the hexagonal phase to be lowest in energy whereas experimentally\nobserved cubic phase lies slightly higher in energy. We optimized the structure\nin both phases and in all different magnetic states to explore the possibility\nof the structural and magnetic phase transitions at ground state. We do not\nfind any phase transitions between the magnetic and non-magnetic phases. The\ncalculated structural, magnetic properties of cubic phase are in excellent\nagreement with experiments. Further, we do not observe half metallic behavior\nin any of the phases. However, the cubic phase does have fewer density of\nstates for down-spin component giving a possibility of forming half metallic\nphase artificially, introducing vacancies, and disorder in lattice."
    },
    {
        "anchor": "PyNanospacing: TEM image processing tool for strain analysis and\n  visualization: The diverse spectrum of material characteristics including band gap,\nmechanical moduli, color, phonon and electronic density of states, along with\ncatalytic and surface properties are intricately intertwined with the atomic\nstructure and the corresponding interatomic bond-lengths. This interconnection\nextends to the manifestation of interplanar spacings within a crystalline\nlattice. Analysis of these interplanar spacings and the comprehension of any\ndeviations, whether it be lattice compression or expansion, commonly referred\nto as strain, hold paramount significance in unraveling various unknowns within\nthe field. Transmission Electron Microscopy (TEM) is widely used to capture\natomic-scale ordering, facilitating direct investigation of interplanar\nspacings. However, creating critical contour maps for visualizing and\ninterpreting lattice stresses in TEM images remains a challenging task. Here we\ndeveloped a Python code for TEM image processing that can handle a wide range\nof materials including nanoparticles, 2D materials, pure crystals and solid\nsolutions. This algorithm converts local differences in interplanar spacings\ninto contour maps allowing for a visual representation of lattice expansion and\ncompression. The tool is very generic and can significantly aid in analyzing\nmaterial properties using TEM images, allowing for a more in-depth exploration\nof the underlying science behind strain engineering via strain contour maps at\nthe atomic level.",
        "positive": "Reconstructed Momentum Density and Fermi Surface in Cu0.9Al0.1: A reconstruction technique based on Radon transforms is used to obtain 3D\nelectron momentum density rho(p) using nine recently measured high-resolution\nCompton profiles (CPs) from a Cu_{0.9}Al_{0.1} disordered alloy single crystal.\nThe method was also applied to nine corresponding theoretical CPs computed\nwithin the KKR-CPA first-principles scheme in order to show that our\nreconstruction procedure reproduces rho(p) reasonably. We comment briefly on\nhow well a map of the Fermi surface (FS) can be obtained by folding the\nreconstructed rho(p) into the first Brillouin zone."
    },
    {
        "anchor": "Threshold voltage and space charge in organic transistors: We investigate rubrene single-crystal field-effect transistors, whose\nstability and reproducibility are sufficient to measure systematically the\nshift in threshold voltage as a function of channel length and source-drain\nvoltage. The shift is due to space-charge transferred from the contacts, and\ncan be modeled quantitatively without free fitting parameters, using Poisson's\nequation, and by assuming that the density of states in rubrene is that of a\nconventional inorganic semiconductor. Our results demonstrate the consistency,\nat the quantitative level, of a variety of recent experiments on rubrene\ncrystals, and show how the use of FET measurements can enable the determination\nof microscopic parameters (e.g., the effective mass of charge carriers).",
        "positive": "First-principles study of mechanical and electronic properties of bent\n  monolayer transition metal dichalcogenides: The mechanical and electronic properties of transition metal dichalcogenide\n(TMD) monolayers corresponding to transition groups IV, VI, and X are explored\nunder mechanical bending from first principles calculations using the strongly\nconstrained and appropriately normed (SCAN) meta-GGA (MGGA). SCAN provides an\naccurate description of the phase stability of the TMD monolayers. Our\ncalculated lattice parameters and other structural parameters agree well with\nexperiment. We find that bending stiffness (or flexural rigidity) increases as\nthe transition metal group goes from IV to X to VI, with the exception of\nPdTe$_2$. Variation in mechanical properties (local strain, physical thickness)\nand electronic properties (local charge density, band structure) with bending\ncurvature is discussed. The local strain profile of these TMD monolayers under\nmechanical bending is highly non-uniform. The mechanical bending tunes not only\nthe thickness of the TMD monolayers but also the local charge distribution as\nwell as the band structures, adding more functionalization options to these\nmaterials."
    },
    {
        "anchor": "Excitonic coupling dominates the homogeneous photoluminescence\n  excitation linewidth in semicrystalline polymeric semiconductors: We measure the homogeneous excitation linewidth of regioregular\npoly(3-hexylthiophene), a model semicrystalline polymeric semiconductor, by\nmeans of two-dimensional coherent photoluminescence excitation spectroscopy. At\na temperature of 8\\,K, we find a linewidth that is always $\\gtrsim 110$\\,meV\nfull-width-at-half-maximum, which is a significant fraction of the total\nlinewidth. It displays a spectral dependence and is minimum near the 0--0\norigin peak. We interpret this spectral dependence of the homogeneous\nexcitation linewidth within the context of a weakly coupled aggregate model.",
        "positive": "Theoretical determination of the Raman spectra of MgSiO3 perovskite and\n  post-perovskite at high pressure: We use the density functional perturbation theory to determine for the first\ntime the pressure evolution of the Raman intensities for a mineral, the two\nhigh-pressure structures of MgSiO3 perovskite and post-perovskite. At high\npressures, the Raman powder spectra reveals three main peaks for the perovskite\nstructure and one main peak for the post-perovskite structure. Due to the large\ndifferences in the spectra of the two phases Raman spectroscopy can be used as\na good experimental indication of the phase transition."
    },
    {
        "anchor": "A Deep-learning Model for Fast Prediction of Vacancy Formation in\n  Diverse Materials: The presence of point defects such as vacancies plays an important role in\nmaterial design. Here, we demonstrate that a graph neural network (GNN) model\ntrained only on perfect materials can also be used to predict vacancy formation\nenergies ($E_{vac}$) of defect structures without the need for additional\ntraining data. Such GNN-based predictions are considerably faster than density\nfunctional theory (DFT) calculations with reasonable accuracy and show the\npotential that GNNs are able to capture a functional form for energy\npredictions. To test this strategy, we developed a DFT dataset of 508 $E_{vac}$\nconsisting of 3D elemental solids, alloys, oxides, nitrides, and 2D monolayer\nmaterials. We analyzed and discussed the applicability of such direct and fast\npredictions. We applied the model to predict 192494 $E_{vac}$ for 55723\nmaterials in the JARVIS-DFT database.",
        "positive": "Ab initio prediction of the mechanical properties of alloys: The case of\n  Ni/Mn-doped ferromagnetic Fe: First-principles alloy theory, formulated within the exact muffin-tin\norbitals method in combination with the coherent-potential approximation, is\nused to study the mechanical properties of ferromagnetic body-centered cubic\n(bcc) Fe$_{1-x}$M$_x$ alloys (M=Mn or Ni, $0\\le x \\le 0.1$). We consider\nseveral physical parameters accessible from \\emph{ab initio} calculations and\ntheir combinations in various phenomenological models to compare the effect of\nMn and Ni on the properties of Fe. Alloying is found to slightly alter the\nlattice parameters and produce noticeable influence on elastic moduli. Both Mn\nand Ni decrease the surface energy and the unstable stacking fault energy\nassociated with the $\\{110\\}$ surface facet and the $\\{110\\}\\langle111\\rangle$\nslip system, respectively. Nickel is found to produce larger effect on the\nplanar fault energies than Mn. The semi-empirical ductility criteria by Rice\nand Pugh consistently predict that Ni enhances the ductility of Fe but give\ncontradictory results in the case of Mn doping. The origin of the discrepancy\nbetween the two criteria is discussed and an alternative measure of the\nductile-brittle behavior based on the theoretical cleavage strength and\nsingle-crystal shear modulus $G\\{110\\}\\langle111\\rangle$ is proposed."
    },
    {
        "anchor": "Transmission Studies of Left-handed Materials: Left-handed materials are studied numerically using an improved version of\nthe transfer-matrix method. The transmission, reflection, the phase of the\nreflection and the absorption are calculated and compared with experiments for\nboth single split-ring resonators (SRR) with negative permeability and\nleft-handed materials (LHMs) which have both the permittivity and permeability\nnegative. Our results suggest ways of positively identifying materials that\nhave both permittivity and permeability negative, from materials that have\neither permeability or permittivity negative.",
        "positive": "Strain, nano-phase separation, multi-scale structures and function of\n  advanced materials: Recent atomic pair distribution function results from our group from\nmanganites and cuprate systems are reviewed in light of the presence of\nmulti-scale structures. These structures have a profound effect on the material\nproperties"
    },
    {
        "anchor": "Intrinsic defects and mid-gap states in quasi-one-dimensional Indium\n  Telluride: Recently, intriguing physical properties have been unraveled in anisotropic\nsemiconductors, in which the in-plane electronic band structure anisotropy\noften originates from the low crystallographic symmetry. The atomic chain is\nthe ultimate limit in material downscaling for electronics, a frontier for\nestablishing an entirely new field of one-dimensional quantum materials.\nElectronic and structural properties of chain-like InTe are essential for\nbetter understanding of device applications such as thermoelectrics. Here, we\nuse scanning tunneling microscopy/spectroscopy (STM/STS) measurements and\ndensity functional theory (DFT) calculations to directly image the in-plane\nstructural anisotropy in tetragonal Indium Telluride (InTe). As results, we\nreport the direct observation of one-dimensional In1+ chains in InTe. We\ndemonstrate that InTe exhibits a band gap of about 0.40 +-0.02 eV located at\nthe M point of the Brillouin zone. Additionally, line defects are observed in\nour sample, were attributed to In1+ chain vacancy along the c-axis, a general\nfeature in many other TlSe-like compounds. Our STS and DFT results prove that\nthe presence of In1+ induces localized gap state, located near the valence band\nmaximum (VBM). This acceptor state is responsible for the high intrinsic p-type\ndoping of InTe that we also confirm using angle-resolved photoemission\nspectroscopy.",
        "positive": "Phononic Helical Nodal Lines with $\\mathcal{PT}$ Protection in MoB$_{2}$: While condensed matter systems host both Fermionic and Bosonic\nquasi-particles, reliably predicting and empirically verifying topological\nstates is only mature for Fermionic electronic structures, leaving topological\nBosonic excitations sporadically explored. This is unfortunate, as Bosonic\nsystems such a phonons offer the opportunity to assess spinless band structures\nwhere nodal lines can be realized without invoking special additional symetries\nto protect against spin-orbit coupling. Here we combine first-principles\ncalculations and meV-resolution inelastic x-ray scattering to demonstrate the\nfirst realization of parity-time reversal ($\\mathcal{PT}$) symmetry protected\nhelical nodal lines in the phonon spectrum of MoB$_{2}$. This structure is\nunique to phononic systems as the spin-orbit coupling present in electronic\nsystems tends to lift the degeneracy away from high-symmetry locations. Our\nstudy establishes a protocol to accurately identify topological Bosonic\nexcitations, opening a new route to explore exotic topological states in\ncrystalline materials."
    },
    {
        "anchor": "An efficient material search for room temperature topological magnons: Topologically protected magnon surface states are highly desirable as an\nideal platform to engineer low-dissipation spintronics devices. However,\ntheoretical prediction of topological magnons in strongly correlated materials\nproves to be challenging because the ab initio density functional theory\ncalculations fail to reliably predict magnetic interactions in correlated\nmaterials. Here, we present a symmetry-based approach, which predicts\ntopological magnons in magnetically ordered crystals, upon applying external\nperturbations such as magnetic/electric fields and/or mechanical strains. We\napply this approach to carry out an efficient search for magnetic materials in\nthe Bilbao Crystallographic Server, where, among 198 compounds with an over\n300-K transition temperature, we identify 12 magnetic insulators that support\nroom-temperature topological magnons. They feature Weyl magnons with surface\nmagnon arcs and magnon axion insulators with either chiral surface or hinge\nmagnon modes, offering a route to realize energy-efficient devices based on\nprotected surface magnons.",
        "positive": "Static disorder and structural correlations in the low temperature phase\n  of lithium imide: Based on ab-initio molecular dynamics simulations, we investigate the low\ntemperature crystal structure of Li2NH which in spite of its great interest as\nH-storage material is still matter of debate. The dynamical simulations reveal\na precise correlation in the fractional occupation of Li sites which leads\naverage atomic positions in excellent agreement with diffraction data and\nsolves inconsistencies of previous proposals."
    },
    {
        "anchor": "Tunnel magnetoresistance of magnetic junctions with cubic symmetry of\n  the layers: A tunnel magnetic junction is considered with magnetic hard and magnetic soft\nlayers of cubic symmetry. The magnetic switching is analyzed of the layers by a\nmagnetic field perpendicular to the initial magnetizations. In such a\nsituation, an additional peak of the TMR ratio appears at the magnetic field\nvalue lower substantially than the anisotropy energy of the soft layer.",
        "positive": "Matrices, bases and matrix elements for cubic double crystallographic\n  groups: Matrices of the irreducible representations of double crystallographic point\ngroups O, Td, Ox{1,I} and Tdx{1,I} are derived. The characteristic polynomials\n(spinor bases) up to the sixth power are obtained. The method for the\nderivation of the general form of an arbitrary matrix element of a\nvector/tensor quantity is developed; as an application, the kp matrix elements\nare calculated. It is demonstrated that the other known method for obtaining\nthe bases of the irreducible representations of the double groups\n(LS-diagonalization of a linear combination of spherical harmonics) is\nunreliable."
    },
    {
        "anchor": "Quantum Mechanical Assessment of Optimal Photovoltaic Conditions in\n  Organic Solar Cells: Recombination losses contribute to reduce $J_{SC}$, $V_{OC}$ and the fill\nfactor of organic solar cells. Recent advances in non-fullerene organic\nphotovoltaics have shown, nonetheless, that efficient charge generation can\noccur under small energetic driving forces ($\\Delta E_{DA}$) and low\nrecombination losses. To shed light on this issue, we set up a coarse-grained\nopen quantum mechanical model for investigating the charge generation dynamics\nsubject to various energy loss mechanisms. The influence of energetic driving\nforce, Coulomb interaction, vibrational disorder, geminate recombination,\ntemperature and external bias are included in the analysis of the optimal\nphotovoltaic conditions for charge carrier generation. The assessment reveals\nthat the overall energy losses are not only minimized when $\\Delta E_{DA}$\napproaches the effective reorganization energy at the interface but also become\ninsensitive to temperature and electric field variations. It is also observed\nthat a moderate reverse bias reduces geminate recombination losses\nsignificantly at vanishing driving forces, where the charge generation is\nstrongly affected by temperature.",
        "positive": "Neutron diffraction studies and the magnetism of an ordered perovskite:\n  Ba2CoTeO6: The complex perovskite Ba2CoTeO6 (BCTO) has been synthesised, and the crystal\nstructure and magnetic properties have been investigated using a combination of\nX-ray and neutron powder diffraction, electron microscopy and dielectric,\ncalorimetric and magnetic measurements. It was shown that at room temperature\nthis compound adopts the 6L-trigonal perovskite structure, space group P-3m (N\n164) (a= 5.7996(1){\\AA}, c=14.2658(3){\\AA}). The structure comprises dimers of\nface-sharing octahedra as well as octahedra which share only vertices with\ntheir neighbours. A long-range antiferromagnetically ordered state has been\nidentified from neutron diffraction and magnetic studies. The magnetic\ndiffraction peaks were registered below the magnetic transition at about 15 K\nand a possible model for the magnetic structure is proposed. The structural and\nmagnetic features of this compound are discussed and compared with those of\nother Co-based quaternary oxides adopting the perovskite structure."
    },
    {
        "anchor": "Electronic bands of III-V semiconductor polytypes and their alignment: The quasiparticle band structures of four polytypes 3C, 6H, 4H, and 2H of\nGaP, GaAs, GaSb, InP, InAs, and InSb are computed with high accuracy including\nspin-orbit interaction applying a recently developed approximate calculation\nscheme, the LDA-1/2 method. The results are used to derive band offsets\n  $\\Delta E_c$ and $\\Delta E_v$ for the conduction and valence bands between\ntwo polytypes. The alignment of the band structures is based on the\nbranch-point energy\n  $E_{\\rm BP}$ for each polytype. The aligned electronic structures are used to\nexplain properties of heterocrystalline but homomaterial junctions.\n  The gaps and offsets allow to discuss spectroscopic results obtained recently\nfor such junctions in III-V nanowires.",
        "positive": "Crystal field excitations and magnons: their roles in oxyselenides\n  Pr2O2M2OSe2 (M = Mn, Fe): We present the results of neutron scattering experiments to study the crystal\nand magnetic structures of the Mott-insulating transition metal oxyselenides\nPr2O2M2OSe2 (M = Mn, Fe). The structural role of the non-Kramers Pr3+ ion is\ninvestigated and analysis of Pr3+ crystal field excitations performed.\nLong-range order of Pr3+ moments in Pr2O2Fe2OSe2 can be induced by an applied\nmagnetic field."
    },
    {
        "anchor": "Electronic and Optical Properties of Oligothiophene-F4TCNQ\n  Charge-Transfer Complexes: The Role of Donor Conjugation Length: We investigate from first-principles many-body theory the role of the donor\nconjugation length in doped organic semiconductors forming charge-transfer\ncomplexes (CTCs) exhibiting partial charge transfer. We consider\noligothiophenes (nT) with an even number of rings ranging from four to ten,\ndoped by the strong acceptor\n2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4TCNQ). The decrease of\nthe electronic gaps upon increasing nT size is driven by the reduction of the\nionization energy with the electron affinity remaining almost constant. The\noptical gaps exhibit a different trend, being at approximately the same energy\nregardless of the donor length. The first excitation retains the same\noscillator strength and Frenkel-like character in all systems. While in\n4T-F4TCNQ also higher-energy excitations preserve this nature, in CTCs with\nlonger nT oligomers charge-transfer excitations and Frenkel excitons localized\non the donor appear above the absorption onset. Our results offer important\ninsight into the structure-property relations of CTCs, thus contributing to a\ndeeper understanding of doped organic semiconductors.",
        "positive": "Quantum-phase two-dimensional materials: The modification of electronic band structures and the subsequent tuning of\nelectrical, optical, and thermal material properties is a central theme in the\nengineering and fundamental understanding of solid-state systems. In this\nscenario, atomically thin materials offer an appealing platform because they\nare extremely susceptible to electric and magnetic gating, as well as to\ninterlayer hybridization in stacked configurations, providing the means to\ncustomize and actively modulate their response functions. Here, we introduce a\nradically different approach to material engineering relying on the\nself-interaction that electrons in a two-dimensional material experience when\nan electrically neutral structure is placed in its vicinity. Employing rigorous\ntheoretical methods, we show that electrons in a semiconductor atomic monolayer\nacquire a quantum phase resulting from the image potential induced by the\npresence of a neighboring periodic array of conducting ribbons, which in turn\nproduces strong modifications in the optical, electrical, and thermal\nproperties of the monolayer, specifically giving rise to the emergence of\ninterband optical absorption, plasmon hybridization, and metal-insulator\ntransitions. Beyond its fundamental interest, material engineering based on the\nquantum phase induced by noncontact neighboring structures represents a\ndisruptive approach to tailor the properties of atomic layers for application\nin nanodevices."
    },
    {
        "anchor": "Andreev Reflection Spectroscopy in Transition Metal Oxides: Here we review the literature concerning measurement of the Andreev\nreflection between a superconductor (S) and ferromagnet (F), with particular\nattention to the case where the ferromagnet is a transition metal oxide. We\ndiscuss the practicality of utilisation of the current models for determination\nof the transport current spin polarisation and examine the evidence for Andreev\nbound states.",
        "positive": "Enhancement of Carrier Mobility in Semiconductor Nanostructures by\n  Dielectric Engineering: We propose a technique for achieving large improvements in carrier mobilities\nin 2- and 1-dimensional semiconductor nanostructures by modifying their\ndielectric environments. We show that by coating the nanostructures with\nhigh-$\\kappa$ dielectrics, scattering from Coulombic impurities can be strongly\ndamped. Though screening is also weakened, the damping of Coulombic scattering\nis much larger, and the resulting improvement in mobilities of carriers can be\nas much as an order of magnitude for thin 2D semiconductor membranes, and more\nfor semiconductor nanowires."
    },
    {
        "anchor": "Intrinsic spin-orbit torque arising from Berry curvature in\n  metallic-magnet/Cu-oxide interface: We report the observation of the intrinsic damping-like spin-orbit torque\n(SOT) arising from the Berry curvature in metallic-magnet/CuO$_x$\nheterostructures. We show that a robust damping-like SOT, an order of magnitude\nlarger than a field-like SOT, is generated in the heterostructure despite the\nabsence of the bulk spin-orbit effect in the CuO$_x$ layer. Furthermore, by\ntuning the interface oxidation level, we demonstrate that the field-like SOT\nchanges drastically and even switches its sign, which originates from oxygen\nmodulated spin-dependent disorder. These results provide an important\ninformation for fundamental understanding of the physics of the SOTs.",
        "positive": "First-principles study of excitonic effects in Raman intensities: The ab initio prediction of Raman intensities for bulk solids usually relies\non the hypothesis that the frequency of the incident laser light is much\nsmaller than the band gap. However, when the photon frequency is a sizeable\nfraction of the energy gap, or higher, resonance effects appear. In the case of\nsilicon, when excitonic effects are neglected, the response of the solid to\nlight increases by nearly three orders of magnitude in the range of frequencies\nbetween the static limit and the gap. When excitonic effects are taken into\naccount, an additional tenfold increase in the intensity is observed. We\ninclude these effects using a finite-difference scheme applied on the\ndielectric function obtained by solving the Bethe-Salpeter equation. Our\nresults for the Raman susceptibility of silicon show stronger agreement with\nexperimental data compared with previous theoretical studies. For the sampling\nof the Brillouin zone, a double-grid technique is proposed, resulting in a\nsignificant reduction in computational effort."
    },
    {
        "anchor": "Critical effect of cubic phase on aging in 3 mol% yttria-stabilized\n  zirconia ceramics for hip replacement prosthesis: The isothermal tetragonal-to-monoclinic transformation of 3Y-TZP ceramics\nsintered at two different temperatures (1450{\\deg}C and 1550{\\deg}C) and\nduration (2 and 5 h) is investigated at 134{\\deg}C in steam. Particular\nattention is paid to the presence of a cubic phase and its effect on isothermal\naging. Sintering at 1550{\\deg}C can result in a significant amount of large\ncubic grains in the specimens, that have a detrimental impact on aging\nresistance, especially for the first stage of the aging process. Cubic grains\nappear to be enriched in yttrium, which in turn leads to a depletion of yttrium\nin the neighboring tetragonal grains. These grains will act as nucleation sites\nfor tetragonal-to-monoclinic transformation. Even for specimens sintered at\nlower temperature, i.e. 1450{\\deg}C, the presence of a cubic phase is expected\nfrom the phase diagram, leading to a significant effect on aging sensitivity.",
        "positive": "Nuclear Spin Crossover in Dense Molecular Hydrogen: The laws of quantum mechanics are often tested against the behaviour of the\nlightest element in the periodic table, hydrogen. One of the most striking\nproperties of molecular hydrogen is the coupling between molecular rotational\nproperties and nuclear spin orientations, giving rise to the spin isomers\northo- and para-hydrogen. At high pressure, as intermolecular interactions\nincrease significantly, the free rotation of H2 molecules is increasingly\nhindered, and consequently a modification of the coupling between molecular\nrotational properties and the nuclear spin system can be anticipated. To date,\nhigh-pressure experimental methods have not been able to observe nuclear spin\nstates at pressures approaching 100 GPa and consequently the effect of high\npressure on the nuclear spin statistics could not be directly measured. Here,\nwe present in-situ high-pressure nuclear magnetic resonance data on molecular\nhydrogen in its hexagonal phase I up to 123 GPa at room temperature. While our\nmeasurements confirm the presence of I=1 ortho-hydrogen at low pressures, above\n70 GPa, where inter- and intramolecular distances become comparable, we observe\na crossover in the nuclear spin statistics from a spin-1 quadrupolar to a\nspin-1/2 dipolar system, evidencing the loss of spin isomer distinction. These\nobservations represent a unique case of a nuclear spin crossover phenomenon in\nquantum solids."
    },
    {
        "anchor": "First-principles Study of Electronic and Dielectric Properties of ZrO2\n  and HfO2: Using density-functional theory with ultrasoft pseudopotentials, we\npreviously investigated the structural and electronic properties of the\nlow-pressure (cubic, tetragonal, and monoclinic) phases of ZrO2 and HfO2, in\norder to elucidate phonon modes, Born effective charge tensors, and especially\nthe lattice dielectric response in these phases. We now extend this previous\nwork by carrying out similar calculations on the two high-pressure orthorhombic\nphases, and by providing density-of-states and band-gap information on all\npolymorphs. Our results show that the electronic structures and dielectric\nresponses are strongly phase-dependent. In particular, the monoclinic phases of\nZrO2 and HfO2 are found to have a strongly anisotropic dielectric tensor and a\nrather small orientational average (epsilon_0) compared to the two other\nlow-pressure phases. Our calculations show that epsilon_0 is even smaller in\nthe orthorhombic phases.",
        "positive": "Lattice correlation of Hubbard excitons in a Mott insulator Sr2IrO4 and\n  reconstruction of their hopping dynamics via time-dependent coherence\n  analysis of the Bragg diffraction: In correlated oxides the coupling of quasiparticles to other degrees of\nfreedom such as spin and lattice plays critical roles in the emergence of\nsymmetry-breaking quantum ordered states such as high temperature\nsuperconductivity. We report a strong lattice coupling of photon induced\nHubbard excitonic quasiparticles in spin-orbital coupling Mott insulator\nSr2IrO4. Combining time-resolved optical spectroscopy techniques, we further\nreconstructed spatiotemporal map of the diffusion of quasiparticles via\ntime-dependent coherence analysis of the x-ray Bragg diffraction peak. Due to\nthe unique electronic configuration of the exciton, the strong lattice\ncorrelation is unexpected but extends the similarity between Sr2IrO4 and\ncuprates under highly non-equilibrium conditions. The coherence analysis method\nwe developed may have important implications for characterizing the structure\nand carrier dynamics in a wider group of oxide heterostructures."
    },
    {
        "anchor": "Nonlinear optical probe of tunable surface electrons on a topological\n  insulator: We use ultrafast laser pulses to experimentally demonstrate that the\nsecond-order optical response of bulk single crystals of the topological\ninsulator Bi$_2$Se$_3$ is sensitive to its surface electrons. By performing\nsurface doping dependence measurements as a function of photon polarization and\nsample orientation we show that second harmonic generation can simultaneously\nprobe both the surface crystalline structure and the surface charge of\nBi$_2$Se$_3$. Furthermore, we find that second harmonic generation using\ncircularly polarized photons reveals the time-reversal symmetry properties of\nthe system and is surprisingly robust against surface charging, which makes it\na promising tool for spectroscopic studies of topological surfaces and buried\ninterfaces.",
        "positive": "Evidence of quasi-2D Fermi surface and non-trivial electronic topology\n  in kagome lattice magnet GdV6Sn6 using de Haas van Alphen oscillations: The shape of the Fermi surface, the effective mass of carriers, and the\ntopologically non-trivial nature of electronic bands of kagome magnet GdV6Sn6\nare investigated using de Haas van Alphen (dHvA) oscillations measurements. Our\ntemperature and angle dependent torque magnetometry measurements reveal at\nleast seven different frequencies ranging from ~90 T up to ~9000 T. These\nfrequencies correspond to extremal areas of Fermi surface ranging from ~1% up\nto 50% of the first Brillouin zone, qualitatively consistent with electronic\nstructure calculations. The angle dependent dHvA oscillations frequencies\nindicate that all pockets of Fermi surface are mostly two-dimensional. We also\nfind evidence of the presence of lighter (0.58 m0) as well as heavier (2.25 m0)\nelectrons through the analysis of the temperature dependence of dominant\nfrequencies, reflecting the features of correlated and Dirac like dispersions\nin the electronic structure. The estimation of the Berry phase indicates the\ntopologically non-trivial nature of the lowest frequency band containing\nlighter electrons. This is consistent with the presence of Dirac-like linear\ndispersion in the electronic structure."
    },
    {
        "anchor": "Macroscopic elastic stress and strain produced by irradiation: Using the notion of eigenstrain produced by the defects formed in a material\nexposed to high energy neutron irradiation, we develop a method for computing\nmacroscopic elastic stress and strain arising in components of a fusion power\nplant during operation. In a microstructurally isotropic material, the primary\ncause of macroscopic elastic stress and strain fields is the spatial variation\nof neutron exposure. We show that under traction-free boundary conditions, the\nvolume-average elastic stress always vanishes, signifying the formation of a\nspatially heterogeneous stress state, combining compressive and tensile elastic\ndeformations at different locations in the same component, and resulting solely\nfrom the spatial variation of radiation exposure. Several case studies\npertinent to the design of a fusion power plant are analysed analytically and\nnumerically, showing that a spatially varying distribution of defects produces\nsignificant elastic stresses in ion-irradiated thin films, pressurised\ncylindrical tubes and breeding blanket modules.",
        "positive": "The role of excitons and trions on electron spin polarization in quantum\n  wells: We have studied the time evolution of the electron spin polarization under\ncontinuous photoexcitation in remotely n-doped semiconductor quantum wells. The\ndoped region allows us to get the necessary excess of free electrons to form\ntrions. We have considered electron resonant photoexcitation at free, exciton\nand trion electron energy levels. Also, we have studied the relative effect of\nphotoexcitation energy density and doping concentration. In order to obtain the\ntwo-dimensional density evolution of the different species, we have performed\ndynamic calculations through the matrix density formalism. Our results indicate\nthat photoexcitation of free electron level leads to a higher spin\npolarization. Also, we have found that increasing the photoexcitation energy or\ndiminishing the doping enhances spin polarization."
    },
    {
        "anchor": "Enhanced Bimolecular Recombination of Charge Carriers in Amorphous\n  Organic Semiconductors: Overcoming the Langevin Limit: We consider the bimolecular charge carrier recombination in amorphous organic\nsemiconductors having a special kind of energetic disorder where energy levels\nfor electrons and holes at a given transport site move in the same direction\nwith the variation of some disorder governing parameter (the parallel\ndisorder). This particular kind of disorder could be found in materials where\nthe dominant part of the energetic disorder is provided by the conformational\ndisorder. Contrary to the recently studied case of electrostatic disorder, the\nconformational disorder, if spatially correlated, leads to the increase of the\nrecombination rate constant which becomes greater than the corresponding\nLangevin rate constant. Probably, organic semiconductors with the dominating\nconformational disorder represent the first class of amorphous organic\nsemiconductors where the recombination rate constant could overcome the\nLangevin limit.",
        "positive": "Electric-field-induced stress relaxation in alpha-phase poly(vinylidene\n  fluoride) films: The relationship between elastic fatigue and electrical cyclic loading in\nalpha-phase poly(vinylidene fluoride) films has been investigated. Our\nexperimental studies have shown that the electric-field-induced fatigue\nbehavior can be described by a stress relaxation, which belongs to the\nKohlrausch function group, and the corresponding exponent is a modified\ntwo-parameter Weibull distribution function."
    },
    {
        "anchor": "Are Small Polarons Always Detrimental to Transparent Conducting Oxides ?: Transparent conducting oxides (TCOs) are essential to many technologies\nincluding solar cells and transparent electronics. The search for high\nperformance n- or p-type TCOs has mainly focused on materials offering\ntransport through band carriers instead of small polarons. In this work, we\nbreak this paradigm and demonstrate using well-known physical models that, in\ncertain circumstances, TCOs exhibiting transport by small polarons offer a\nbetter combination of transparency and conductivity than materials conducting\nthrough band transport. We link this surprising finding to the fundamentally\ndifferent physics of optical absorption for band and polaronic carriers. Our\nwork rationalizes the good performances of recently emerging small-polaronic\nCr-based p-type TCOs such as Sr-doped LaCrO$_3$ and outlines design principles\nfor the development of high-performance TCOs based on transport by small\npolarons. This opens new avenues for the discovery of high-performance TCOs\nespecially p-type.",
        "positive": "Optimized substrates and measurement approaches for Raman spectroscopy\n  of graphene nanoribbons: The on-surface synthesis of graphene nanoribbons (GNRs) allows for the\nfabrication of atomically precise narrow GNRs. Despite their exceptional\nproperties which can be tuned by ribbon width and edge structure, significant\nchallenges remain for GNR processing and characterization. In this\ncontribution, we use Raman spectroscopy to characterize different types of GNRs\non their growth substrate and to track their quality upon substrate transfer.\nWe present a Raman-optimized (RO) device substrate and an optimized mapping\napproach that allows for acquisition of high-resolution Raman spectra,\nachieving enhancement factors as high as 120 with respect to signals measured\non standard SiO2/Si substrates. We show that this approach is well-suited to\nroutinely monitor the geometry-dependent low-frequency modes of GNRs. In\nparticular, we track the radial breathing-like mode (RBLM) and the shear-like\nmode (SLM) for 5-, 7- and 9-atom wide armchair GNRs (AGNRs) and compare their\nfrequencies with first-principles calculations."
    },
    {
        "anchor": "Exact dynamical exchange-correlation kernel of a weakly inhomogeneous\n  electron gas: The dynamical exchange-correlation kernel $f_{xc}$ of a non-uniform electron\ngas is an essential input for the time-dependent density functional theory of\nelectronic systems. The long-wavelength behavior of this kernel is known to be\nof the form $f_{xc}= \\alpha/q^2$ where $q$ is the wave vector and $\\alpha$ is a\nfrequency-dependent coefficient. We show that in the limit of weak\nnon-uniformity the coefficient $\\alpha$ has a simple and exact expression in\nterms of the ground-state density and the frequency-dependent kernel of a {\\it\nuniform} electron gas at the average density. We present an approximate\nevaluation of this expression for Si and discuss its implications for the\ntheory of excitonic effects.",
        "positive": "Nonlinear conductivity in CaRuO3 thin films measured by short current\n  pulses: Metals near quantum critical points have been predicted to display universal\nout-of equilibrium behavior in the steady current-carrying state. We have\nstudied the non-linear conductivity of high-quality CaRuO$_3$ thin films with\nresidual resistivity ratio up to 57 using micro-second short, high-field\ncurrent pulses at low temperatures. Even for the shortest pulses of $5\\mu$s,\nJoule heating persists, making it impossible to observe a possible universal\nnon-linearity. Much shorter pulses are needed for the investigation of\nuniversal non-linear conductivity."
    },
    {
        "anchor": "Origin of multistate resistive switching in Ti/manganite/Si$O_x$/Si\n  heterostructures: We report on the growth and characterization of\nTi/$La_{1/3}$$Ca_{2/3}$Mn$O_3$/Si$O_x$/n-Si memristive devices. We demonstrate\nthat using current as electrical stimulus unveils an intermediate resistance\nstate, in addition to the usual high and low resistance states that are\nobserved in standard voltage controlled experiments. Based on thorough\nelectrical characterization (impedance spectroscopy, current-voltage curves\nanalysis), we disclose the contribution of three different microscopic regions\nof the device to the transport properties: an ohmic incomplete metallic\nfilament, a thin manganite layer below the filament tip exhibiting\nPoole-Frenkel like conduction, and the SiOx layer with an electrical response\nwell characterized by a Child-Langmuir law. Our results suggest that the\nexistence of the SiOx layer plays a key role in the stabilization of the\nintermediate resistance level, indicating that the combination of two or more\nactive RS oxides adds functionalities in relation to single-oxide devices. We\nunderstand that these multilevel devices are interesting and promising as their\nfabrication procedure is rather simple and they are fully compatible with\nstandard Si-based electronics.",
        "positive": "Origin of correlated diffuse scattering in the hexagonal manganites: We use a combination of first-principles density functional calculations and\nspin-dynamics simulations to explain the unusual diffuse inelastic neutron\nscattering in the hexagonal multiferroic yttrium manganite, YMnO$_3$. Using\nsymmetry considerations, we construct a model spin Hamiltonian with parameters\nderived from our density functional calculations and show that it captures the\nmeasured behavior. We then show that the observed directionality in the\nstructured diffuse scattering in momentum space is a hallmark of the triangular\ngeometry, and that its persistence across a wide range of temperatures, both\nabove and below the N\\'eel temperature, T$_\\text{N}$, is a result of the strong\nmagnetic frustration. We predict that this diffuse scattering exists in a\nyet-to-be-observed modulated continuum of energies, that its associated spin\nexcitations have distinct in-plane and out-of-plane character and that the\nfrustration influences the magnetism below the N\\'eel temperature. Finally, we\nshow that visualizing the magnetic order in terms of composite trimer\nmagnetoelectric monopoles and toroidal moments, rather than individual spins,\nprovides insight into the real space fluctuations, revealing clusters of\nemerging order in the paramagnetic state, as well as collective short-range\nexcitations in the ordered antiferromagnetic phase. Our understanding of this\ndirectional diffuse scattering in such a wide temperature range, both below and\nabove T$_\\text{N}$, provides new insight into the magnetic phase transitions in\nfrustrated systems."
    },
    {
        "anchor": "Quantitative measurement of the surface charge density: We present a method of measuring the charge density on dielectric surfaces.\nSimilar to electrostatic force microscopy we record the electrostatic\ninteraction between the probe and the sample surface, but at large tip-sample\ndistances. For calibration we use a pyroelectric sample which allows us to\nalter the surface charge density by a known amount via a controlled temperature\nchange. For proof of principle we determined the surface charge density under\nambient conditions of ferroelectric lithium niobate.",
        "positive": "Large magnetic gap at the Dirac point in a Mn-induced Bi$_2$Te$_3$\n  heterostructure: Magnetically doped topological insulators enable the quantum anomalous Hall\neffect (QAHE) which provides quantized edge states for lossless charge\ntransport applications. The edge states are hosted by a magnetic energy gap at\nthe Dirac point but all attempts to observe it directly have been unsuccessful.\nThe gap size is considered crucial to overcoming the present limitations of the\nQAHE, which so far occurs only at temperatures one to two orders of magnitude\nbelow its principle limit set by the ferromagnetic Curie temperature $T_C$.\nHere, we use low temperature photoelectron spectroscopy to unambiguously reveal\nthe magnetic gap of Mn-doped Bi$_2$Te$_3$ films, which is present only below\n$T_C$. Surprisingly, the gap turns out to be $\\sim$90 meV wide, which not only\nexceeds $k_BT$ at room temperature but is also 5 times larger than predicted by\ndensity functional theory. By an exhaustive multiscale structure\ncharacterization we show that this enhancement is due to a remarkable structure\nmodification induced by Mn doping. Instead of a disordered impurity system, it\nforms an alternating sequence of septuple and quintuple layer blocks, where Mn\nis predominantly incorporated in the septuple layers. This self-organized\nheterostructure substantially enhances the wave-function overlap and the size\nof the magnetic gap at the Dirac point, as recently predicted. Mn-doped\nBi$_2$Se$_3$ forms a similar heterostructure, however, only a large,\nnonmagnetic gap is formed. We explain both differences based on the higher\nspin-orbit interaction in Bi$_2$Te$_3$ with the most important consequence of a\nmagnetic anisotropy perpendicular to the films, whereas for Bi$_2$Se$_3$ the\nspin-orbit interaction it is too weak to overcome the dipole-dipole\ninteraction. Our findings provide crucial insights for pushing the lossless\ntransport properties of topological insulators towards room-temperature\napplications."
    },
    {
        "anchor": "Quantum spin Hall phase in neutral zigzag graphene ribbons: We present a detailed description of the nature of the wavefunction and spin\ndistribution of the zero energy modes of zigzag graphene ribbons (ZGRs) in the\npresence of the intrinsic spin_orbit (I-SO) interaction. These states\ncharacterize the quantum spin Hall (QSH) phase in graphene ribbons. We provide\nanalytic expressions for wavefunctions and show how these evolve as the\nstrength of the interaction and the ribbon width are changed. For odd-width\nribbons, we show that its insulating nature precludes the existence of a QSH\nphase. For these systems the I-SO interaction is predicted to have a stronger\neffect as shown by the enhancement of the gap as the interaction strength is\nturned on.",
        "positive": "Low Temperature Ageing Behaviour of U-Nb $\u03b1''$ Phase Alloys: Ageing mechanisms of the U-5\\,\\%wtNb system have been investigated on samples\nexposed to temperatures of 150$\\,^{\\circ}$C for up to 5000\\,hours. A variety of\nsurface and bulk analytic techniques have been used to investigate phase,\nchemical and crystallographic changes. Characterisation of microstructural\nevolution was carried out through secondary electron microscopy (SEM), energy\ndispersive x-ray spectroscopy (EDS), electron backscatter diffraction (EBSD),\ntransmission electron microscopy (TEM) and x-ray diffraction (XRD). This\ninvestigation suggests crystallographic defects such as twinning furthers the\nmartensitic tendencies with ageing. Resizing of the lattice and shuffling of\natoms results in a small progression from the $\\alpha''$ towards the $\\alpha'$\nphase."
    },
    {
        "anchor": "Observation of a two-dimensional electron gas at the surface of annealed\n  SrTiO3 single crystals by scanning tunneling spectroscopy: Scanning tunneling spectroscopy suggests the formation of a two dimensional\nelectron gas (2DEG) on the TiO2 terminated surface of undoped SrTiO3 single\ncrystals annealed at temperature lower than 400 {\\deg}C in ultra high vacuum\nconditions. Low energy electron diffraction indicates that the 2D metallic\nSrTiO3 surface is not structurally reconstructed, suggesting that non-ordered\noxygen vacancies created in the annealing process introduce carriers leading to\nan electronic reconstruction. The experimental results are interpreted in a\nframe of competition between oxygen diffusion from the bulk to the surface and\noxygen loss from the surface itself.",
        "positive": "Space-charge effects in high-energy photoemission: Pump-and-probe photoelectron spectroscopy (PES) with femtosecond pulsed\nsources opens new perspectives in the investigation of the ultrafast dynamics\nof physical and chemical processes at the surfaces and interfaces of solids.\nNevertheless, for very intense photon pulses a large number of photoelectrons\nare simultaneously emitted and their mutual Coulomb repulsion is sufficiently\nstrong to significantly modify their trajectory and kinetic energy. This\nphenomenon, referred as space-charge effect, determines a broadening and shift\nin energy for the typical PES structures and a dramatic loss of energy\nresolution. In this article we examine the effects of space charge in PES with\na particular focus on time-resolved hard X-ray (~10 keV) experiments. The\ntrajectory of the electrons photoemitted from pure Cu in a hard X-ray PES\nexperiment has been reproduced through $N$-body simulations and the broadening\nof the photoemission core-level peaks has been monitored as a function of\nvarious parameters (photons per pulse, linear dimension of the photon spot,\nphoton energy). The energy broadening results directly proportional to the\nnumber $N$ of electrons emitted per pulse (mainly represented by secondary\nelectrons) and inversely proportional to the linear dimension $a$ of the photon\nspot on the sample surface, in agreement with the literature data about\nultraviolet and soft X-ray experiments. The evolution in time of the energy\nbroadening during the flight of the photoelectrons is also studied. Despite its\ndetrimental consequences on the energy spectra, we found that space charge has\nnegligible effects on the momentum distribution of photoelectrons and a\nmomentum broadening is not expected to affect angle-resolved experiments.\nStrategy to reduce the energy broadening and the feasibility of hard X-ray PES\nexperiments at the new free-electron laser facilities are discussed."
    },
    {
        "anchor": "Ab Initio Discovery of Novel Crystal Structure Stability in Barium and\n  Sodium-Calcium Compounds under Pressure using DFT: Group I/II materials exhibit unexpected structural phase transitions at high\npressures, providing potential insight into the origins of elemental\nsuperconductivity. We present here a computational study of elemental barium\nand binary sodium-calcium alloys to identify both known and unknown phases of\nbarium under pressure, as well as stable high-pressure compounds in the\nimmiscible Na-Ca system. To predict stability, we performed density functional\ntheory calculations on randomly generated structures and evolved them using a\ngenetic algorithm. For barium, we observed all of the expected phases and a\nnumber of new metastable structures, excluding the incommensurate Ba-IV\nstructure. We also observed a heretofore unreported structure (\\alpha-Sm)\npredicted to be the ground state from 30-42 GPa. In the Na-Ca system, we\ndemonstrate feasibility of our search method, but have been unable to predict\nany stable compounds. These results have improved the efficacy of the genetic\nalgorithm, and should provide many promising directions for future work.",
        "positive": "Mesoscale simulations of shockwave energy dissipation via chemical\n  reactions: We use a particle-based mesoscale model that incorporates chemical reactions\nat a coarse-grained level to study the response of materials that undergo\nvolume-reducing chemical reactions under shockwave-loading conditions. We find\nthat such chemical reactions can attenuate the shockwave and characterize how\nthe parameters of the chemical model affect this behavior. The simulations show\nthat the magnitude of the volume collapse and velocity at which the chemistry\npropagates are critical to weaken the shock, whereas the energetics in the\nreactions play only a minor role. Shock loading results in transient states\nwhere the material is away from local equilibrium and, interestingly, chemical\nreactions can nucleate under such non-equilibrium states. Thus, the timescales\nfor equilibration between the various degrees of freedom in the material affect\nthe shock-induced chemistry and its ability to attenuate the propagating shock."
    },
    {
        "anchor": "Rotational modes in molecular magnets with antiferromagnetic Heisenberg\n  exchange: In an effort to understand the low temperature behavior of recently\nsynthesized molecular magnets we present numerical evidence for the existence\nof a rotational band in systems of quantum spins interacting with\nnearest-neighbor antiferromagnetic Heisenberg exchange. While this result has\npreviously been noted for ring arrays with an even number of spin sites, we\nfind that it also applies for rings with an odd number of sites as well as for\nall of the polytope configurations we have investigated (tetrahedron, cube,\noctahedron, icosahedron, triangular prism, and axially truncated icosahedron).\nIt is demonstrated how the rotational band levels can in many cases be\naccurately predicted using the underlying sublattice structure of the spin\narray. We illustrate how the characteristics of the rotational band can provide\nvaluable estimates for the low temperature magnetic susceptibility.",
        "positive": "Impact of nitrogen incorporation on interface states in (100)Si/HfO2: The influence of nitrogen incorporation on the energy distribution of\ninterface states in the (100)Si/HfO2 system and their passivation by hydrogen\nhave been studied. The results are compared to those of nominally N-free\nsamples. The nitrogen in the (100)Si/HfO2 entity is found to increase the trap\ndensity, most significantly, in the upper part of Si band gap, in which energy\nrange nitrogen incorporation prevents passivation of interface traps by\nhydrogen. At the same time, passivation of fast interface traps in the lower\npart of the band gap proceeds efficiently, provided the thickness of the\nnitrogen containing interlayer is kept within a few monolayers. The minimal\ninterface trap density below the midgap achieved after passivation in H2 is\ndominated by the presence of slow N-related states, likely located in the\ninsulator. As inferred from capacitance-voltage and ac conductance analysis,\nthe lowest density of electrically active defects [(8-9)x10 10 eV-1cm-2 at\n0.4-0.5 eV from the top of the Si valence band edge] is achieved both in the\nN-free and N-containing (100)Si/HfO2 structuresafter post-deposition anneal at\n800C in (N2+5%O2) followed by passivation in molecular hydrogen at 400C for 30\nmin."
    },
    {
        "anchor": "T>0 ensemble state density functional theory revisited: A logical foundation of equilibrium state density functional theory in a\nKohn-Sham type formulation is presented on the basis of Mermin's treatment of\nthe grand canonical state. it is simpler and more satisfactory compared to the\nusual derivation of ground state theory, and free of remaining open points of\nthe latter. It may in particular be relevant with respect to cases of\nspontaneous symmetry breaking like non-collinear magnetism and orbital order.",
        "positive": "Transformation Pathways of Silica under High Pressure: Concurrent molecular dynamics simulations and ab initio calculations show\nthat densification of silica under pressure follows a ubiquitous two-stage\nmechanism. First, anions form a close-packed sub-lattice, governed by the\nstrong repulsion between them. Next, cations redistribute onto the interstices.\nIn cristobalite silica, the first stage is manifest by the formation of a\nmetastable phase, which was observed experimentally a decade ago, but never\nindexed due to ambiguous diffraction patterns. Our simulations conclusively\nreveal its structure and its role in the densification of silica."
    },
    {
        "anchor": "Local Temperature Redistribution and Structural Transition During\n  Joule-Heating-Driven Conductance Switching in VO2: Joule-heating induced conductance-switching is studied in VO2, a Mott\ninsulator. Complementary in-situ techniques including optical characterization,\nblackbody microscopy, scanning transmission x-ray microscopy (STXM) and\nnumerical simulations are used. Abrupt redistribution in local temperature is\nshown to occur upon conductance-switching along with a structural phase\ntransition, at the same current.",
        "positive": "Comparison of the Green-Kubo and homogeneous non-equilibrium molecular\n  dynamics methods for calculating thermal conductivity: Different molecular dynamics methods like the direct method, the Green-Kubo\n(GK) method and homogeneous non-equilibrium molecular dynamics (HNEMD) method\nhave been widely used to calculate lattice thermal conductivity\n($\\kappa_\\ell$). While the first two methods have been used and compared quite\nextensively, there is a lack of comparison of these methods with the HNEMD\nmethod. Focusing on the underlying computational parameters, we present a\ndetailed comparison of the GK and HNEMD methods for both bulk and vacancy Si\nusing the Stillinger-Weber potential. For the bulk calculations, we find both\nmethods to perform well and yield $\\kappa_\\ell$ within acceptable\nuncertainties. In case of the vacancy calculations, HNEMD method has a slight\nadvantage over the GK method as it becomes computationally cheaper for lower\n$\\kappa_\\ell$ values. This study could promote the application of HNEMD method\nin $\\kappa_\\ell$ calculations involving other lattice defects like nanovoids,\ndislocations, interfaces."
    },
    {
        "anchor": "Fast and accessible first-principles calculations of vibrational\n  properties of materials: We present example applications of an approach to first-principles\ncalculations of vibrational properties of materials implemented within the\nExabyte.io platform. We deploy models based on the Density Functional\nPerturbation Theory to extract the phonon dispersion relations and densities of\nstates for an example set of 35 samples and find the results to be in agreement\nwith prior similar calculations. We construct modeling workflows that are both\naccessible, accurate, and efficient with respect to the human time involved.\nThis is achieved through efficient parallelization of the tasks for the\nindividual vibrational modes. We report achieved speedups in the 10-100 range,\napproximately, and maximum attainable speedups in the 30-300 range,\ncorrespondingly. We analyze the execution times on the current up-to-date\ncomputational infrastructure centrally available from a public cloud provider.\nResults and all associated data, including the materials and simulation\nworkflows, are made available online in an accessible, repeatable and\nextensible setting.",
        "positive": "Microscopic Electronic Wavefunction and interactions between quasi\n  particles in Empirical Tight-Binding Theory: A procedure to obtain single-electron wavefunctions within the tight-binding\nformalism is proposed. It is based on linear combinations of Slater-type\norbitals whose screening coefficients are extracted from the optical matrix\nelements of the tight-binding Hamiltonian. Bloch functions obtained for\nzinc-blende semiconductors in the extended-basis spds* tight-binding model\ndemonstrate very good agreement with first-principles wavefunctions. We apply\nthis method to the calculation of electron-hole exchange interaction, and\nobtain the dispersion of excitonic fine structure of bulk GaAs. Beyond\nsemiconductor nanostructures, this work is a fundamental step toward modeling\nmany-body effects from post-processing single particle wavefunctions within the\ntight-binding theory."
    },
    {
        "anchor": "Which Ion Dominates Temperature and Pressure Response of Halide\n  Perovskites and Elpasolites?: Halide perovskite and elpasolite semiconductors are extensively studied for\noptoelectronic applications due to their excellent performance together with\nsignificant chemical and structural flexibility. However, there is still\nlimited understanding of their basic elastic properties and how they vary with\ncomposition and temperature, which is relevant for synthesis and device\noperation. To address this, we performed temperature- and pressure-dependent\nsynchrotron-based powder X-ray diffraction (XRD). In contrast to previous\npressure-dependent XRD studies, our relatively low pressures (ambient to 0.06\nGPa) enabled us to investigate the elastic properties of halide perovskites and\nelpasolites in their ambient crystal structure. We find that halide perovskites\nand elpasolites show common trends in the bulk modulus and thermal expansivity.\nBoth materials become softer as the halide ionic radius increases from Cl to Br\nto I, exhibiting higher compressibility and larger thermal expansivity. The\nmixed-halide compositions show intermediate properties to the pure compounds.\nContrary, cations show a minor effect on the elastic properties. Finally, we\nobserve that thermal phase transitions in e.g., MAPbI3 and CsPbCl3 lead to a\nsoftening of the lattice, together with negative expansivity for certain\ncrystal axes, already tens of degrees away from the transition temperature.\nHence, the range in which the phase transition affects thermal and elastic\nproperties is substantially broader than previously thought. These findings\nhighlight the importance of considering the temperature-dependent elastic\nproperties of these materials, since stress induced during manufacturing or\ntemperature sweeps can significantly impact the stability and performance of\nthe corresponding devices.",
        "positive": "Tailoring Exchange Couplings in Magnetic Topological\n  Insulator/Antiferromagnet Heterostructures: Magnetic topological insulators such as Cr-doped (Bi,Sb)2Te3 provide a\nplatform for the realization of versatile time-reversal symmetry-breaking\nphysics. By constructing heterostructures with N\\'eel order in an\nantiferromagnetic CrSb and magnetic topological order in Cr-doped (Bi,Sb)2Te3,\nwe realize emergent interfacial magnetic phenomena which can be tailored\nthrough artificial structural engineering. Through deliberate geometrical\ndesign of heterostructures and superlattices, we demonstrate the use of\nantiferromagnetic exchange coupling in manipulating the magnetic properties of\nthe topological surface massive Dirac fermions. This work provides a new\nframework on integrating topological insulators with antiferromagnetic\nmaterials and unveils new avenues towards dissipationless topological\nantiferromagnetic spintronics."
    },
    {
        "anchor": "Evolutionary Metadynamics: a Novel Method to Predict Crystal Structures: A novel method for crystal structure prediction, based on metadynamics and\nevolutionary algorithms, is presented here. This technique can be used to\nproduce efficiently both the ground state and metastable states easily\nreachable from a reasonable initial structure. We use the cell shape as\ncollective variable and evolutionary variation operators developed in the\ncontext of the USPEX method [Oganov, Glass, \\textit{J. Chem. Phys.}, 2006,\n\\textbf{124}, 244704; Lyakhov \\textit{et al., Comp. Phys. Comm.}, 2010,\n\\textbf{181}, 1623; Oganov \\textit{et al., Acc. Chem. Res.}, 2011, \\textbf{44},\n227] to equilibrate the system as a function of the collective variables. We\nillustrate how this approach helps one to find stable and metastable states for\nAl$_2$SiO$_5$, SiO$_2$, MgSiO$_3$, and carbon. Apart from predicting crystal\nstructures, the new method can also provide insight into mechanisms of phase\ntransitions.",
        "positive": "Model for a Macroscopically Disordered Conductor with an Exactly Linear\n  High-Field Magnetoresistance: We calculate the effective resistivity of a macroscopically disordered two\ndimensional conductor consisting of two components in a perpendicular magnetic\nfield. When two components have equal area fractions, we use a duality theorem\nto show that the magnetoresistance is non-saturating and at high fields varies\nexactly linearly with magnetic field. At other compositions, an effective\nmedium calculation leads to a saturating magnetoresistance. We briefly discuss\npossible connections between these results and magnetoresistance measurements\non heavily disordered chalconide semiconductors."
    },
    {
        "anchor": "Non-magnetic ground state of Ni adatoms on Te-terminated bismuth\n  chalcogenide topological insulators: We report on the quenching of single Ni adatom moments on Te-terminated\nBi2Te2Se and Bi2Te3 topological insulator surfaces. The effect becomes\nmanifested as a missing X-ray magnetic circular dichroism for resonant L3,2\ntransitions into partially filled Ni 3d states of occupancy n_d = 9.2. On the\nbasis of a comparative study of Ni and Fe using scanning tunneling microscopy\nand ab initio calculations we are able to relate the element specific moment\nformation to a local Stoner criterion. While Fe adatoms form large spin moments\nof m_s = 2.54 mu_B with out-of-plane anisotropy due to a sufficiently large\ndensity of states at the Fermi energy, Ni remains well below an effective\nStoner threshold for local moment formation. With the Fermi level remaining in\nthe bulk band gap after adatom deposition, non-magnetic Ni and preferentially\nout-of-plane oriented magnetic Fe with similar structural properties on\nBi2Te2Se surfaces constitute a perfect platform to study off-on effects of\ntime-reversal symmetry breaking on topological surface states.",
        "positive": "Inversion symmetry breaking induced triply degenerate points in orderly\n  arranged PtSeTe family materials: $k$ paths exactly with $C_{3v}$ symmetry allow to find triply degenerate\npoints (TDPs) in band structures. The paths that host the type-II Dirac points\nin PtSe$_2$ family materials also have the $C_{3v}$ spatial symmetry. However,\ndue to Kramers degeneracy (the systems have both inversion symmetry and time\nreversal symmetry), the crossing points in them are Dirac ones. In this work,\nbased on symmetry analysis, first-principles calculations, and $k\\cdot p$\nmethod, we predict that PtSe$_2$ family materials should undergo topological\ntransitions if the inversion symmetry is broken, \\emph{i.e.} the Dirac fermions\nin PtSe$_2$ family materials split into TDPs in PtSeTe family materials (PtSSe,\nPtSeTe, and PdSeTe) with orderly arranged S/Se (Se/Te). It is different from\nthe case in high-energy physics that breaking inversion symmetry $I$ leads to\nthe splitting of Dirac fermion into Weyl fermions. We also address a possible\nmethod to achieve the orderly arranged in PtSeTe family materials in\nexperiments. Our study provides a real example that Dirac points transform into\nTDPs, and is helpful to investigate the topological transition between Dirac\nfermions and TDP fermions."
    },
    {
        "anchor": "Exciton mass and exciton spectrum in the cuprous oxide: Excitons with a radius of a few lattice constants can be affected by strong\ncentral-cell corrections, leading to significant deviations of the optical\nspectrum from the hydrogen-like Rydberg series, and also to an enhancement of\nthe exciton mass. We present an approach to this situation based on a lattice\nmodel that incorporates the effects of a non-parabolic band structure, short\ndistance corrections to the Coulomb interaction between electrons and holes,\nspin-orbit and exchange coupling. The lattice model allows for observation of\nthe crossover from large radius Wannier to small radius Frenkel excitons\nwithout invoking a continuum approximation. We apply the lattice model approach\nespecially to the yellow exciton series in the cuprous oxide, for which the\noptical spectrum and exciton mass enhancement are obtained through adaptation\nof only a few model parameters to material-specific values. Our results predict\na strongly anisotropic ortho-exciton mass.",
        "positive": "Controlling the Polarity of the Transient Ferromagnetic-Like State in\n  Ferrimagnets: After the application of an ultrashort laser pulse, the antiferromagnetic\nalignment in rare earth-transition metal alloys can temporarily become\nferromagnetic with the rare-earth polarity.\n  Proposed models merely describe this effect, without showing the route for\nits manipulation. Here we use extensive atomistic spin model simulations and\nmicromagnetic theory for ferrimagnets at elevated temperatures to predict that\nthe polarity of this transient ferromagnetic-like state can be controlled by\ninitial temperature. We show that this arises because the magnetic response of\neach lattice has a different temperature dependence, at low temperatures the\ntransition metal responds faster than the rare earth, while at high\ntemperatures this role is interchanged. Our findings contribute to the physical\nunderstanding and control of this state and thus open new perspectives for its\nuse in ultrafast magnetic devices."
    },
    {
        "anchor": "From 2D to 3D: graphene moulding for transparent and flexible probes: Chemical vapor deposition (CVD) has been widely adopted as the most scalable\nmethod to obtain single layer graphene. Incorporating CVD graphene in planar\ndevices can be performed via well established wet transfer methods or thermal\nadhesive release. Nevertheless, for applications involving 3D shapes, methods\nadopted for planar surface provide only a crude solution if a continuous,\ntear-free, wrinkle-free graphene layer is required. In this work, we present\nthe fabrication and characterization of PDMS-supported 3D graphene probes. To\naccommodate 3D geometries, we perform CVD on catalysts possessing a non-trivial\n3D topology, serving to mold the grown graphene to a final non-trivial 3D\nshape. This advance overcomes challenges observed in standard transfer\nprocesses that can result in uneven coverage, wrinkles and tears. To\ndemonstrate the potential of our new transfer approach, we apply it to\nfabricate graphene electrical probes. Graphene, due to its flexibility,\ntransparency and conductivity, is an ideal material with which to replace\nconventional metal based probes. In particular, with a contact resistance in\nthe order of tens of kOhm, these graphene probes may find applications, such as\nin electrophysiology studies.",
        "positive": "55~Tesla coercive magnetic field in frustrated Sr$_3$NiIrO$_6$: We have measured extremely large coercive magnetic fields of up to 55~T in\nSr$_3$NiIrO$_6$, with a switched magnetic moment $\\approx 0.8~\\mu_{\\rm B}$ per\nformula unit. As far as we are aware, this is the largest coercive field\nobserved thus far. This extraordinarily hard magnetism has a completely\ndifferent origin from that found in conventional ferromagnets. Instead, it is\ndue to the evolution of a frustrated antiferromagnetic state in the presence of\nstrong magnetocrystalline anisotropy due to the overlap of spatially-extended\nIr$^{4+}$ 5$d$ orbitals with oxygen 2$p$ and Ni$^{2+}$ 3$d$ orbitals. This work\nhighlights the unusual physics that can result from combining the extended $5d$\norbitals in Ir$^{4+}$ with the frustrated behaviour of triangular lattice\nantiferromagnets."
    },
    {
        "anchor": "First-principles study of excitons in the optical spectra of silver\n  chloride: Silver chloride is a material that has been investigated and used for many\ndecades. Of particular interest are its optical properties, but only few\nfundamental theoretical studies exist. We present first-principles results for\nthe optical properties of AgCl, obtained using time-dependent density\nfunctional theory and many-body perturbation theory. We show that optical\nproperties exhibit strong excitonic effects, which are correctly captured only\nby solving the Bethe-Salpeter equation starting from quasiparticle\nself-consistent GW results. Numerical simulations are made feasible by using a\nmodel screening for the electron-hole interaction in a way that avoids the\ncalculation of the static dielectric constant. A thorough analysis permits us\nto discuss localization in bright and dark excitons of silver chloride.",
        "positive": "Robustness of avalanche dynamics in sheared amorphous solids as probed\n  by transverse diffusion: Using numerical simulations, we perform an extensive finite-size analysis of\nthe transverse diffusion coefficient in a sheared 2D amorphous solid, over a\nbroad range of strain rates, at temperatures up to the supercooled liquid\nregime. We thus obtain direct qualitative evidence for the persistence of\ncorrelations between elementary plastic events up to the vicinity of the glass\ntransition temperature $T_g$. A quantitative analysis of the data, combined\nwith a previous study of the $T$- and $\\dot\\gamma$-dependence of the\nmacroscopic stress \\cite{ChattorajCaroliLemaitre2010}, leads us to conclude\nthat the average avalanche size remains essentially unaffected by temperature\nup to $T\\sim0.75 T_g$."
    },
    {
        "anchor": "Theory of the spontaneous buckling of doped graphene: Graphene is a realization of an esoteric class of materials -- electronic\ncrystalline membranes. We study the interplay between the free electrons and\nthe two-dimensional crystal, and find that it induces a substantial effect on\nthe elastic structure of the membrane. For the hole-doped membrane, in\nparticular, we predict a spontaneous buckling. In addition, attenuation of\nelastic waves is expected, due to the effect of corrugations on the bulk\nmodulus. These discoveries have a considerable magnitude in graphene, affecting\nboth its mesoscopic structure, and its electrical resistivity, which has an\ninherent asymmetry between hole- and electron-doped graphene.",
        "positive": "Ni(111)|Graphene|h-BN Junctions as Ideal Spin Injectors: Deposition of graphene on top of hexagonal boron nitride (h-BN) was very\nrecently demonstrated while graphene is now routinely grown on Ni. Because the\nin-plane lattice constants of graphite, h-BN, graphite-like BC2N and of the\nclose-packed surfaces of Co, Ni and Cu match almost perfectly, it should be\npossible to prepare ideal interfaces between these materials which are\nrespectively, a semimetal, insulator, semiconductor, ferromagnetic and\nnonmagnetic metals. Using parameter-free energy minimization and electronic\ntransport calculations, we show how h-BN can be combined with the perfect spin\nfiltering property of Ni|graphite and Co|graphite interfaces to make perfect\ntunnel junctions or ideal spin injectors (SI) with any desired resistance-area\nproduct."
    },
    {
        "anchor": "Human Perception-Inspired Grain Segmentation Refinement Using\n  Conditional Random Fields: Accurate segmentation of interconnected line networks, such as grain\nboundaries in polycrystalline material microstructures, poses a significant\nchallenge due to the fragmented masks produced by conventional computer vision\nalgorithms, including convolutional neural networks. These algorithms struggle\nwith thin masks, often necessitating intricate post-processing for effective\ncontour closure and continuity. Addressing this issue, this paper introduces a\nfast, high-fidelity post-processing technique, leveraging domain knowledge\nabout grain boundary connectivity and employing conditional random fields and\nperceptual grouping rules. This approach significantly enhances segmentation\nmask accuracy, achieving a 79% segment identification accuracy in validation\nwith a U-Net model on electron microscopy images of a polycrystalline oxide.\nAdditionally, a novel grain alignment metric is introduced, showing a 51%\nimprovement in grain alignment, providing a more detailed assessment of\nsegmentation performance for complex microstructures. This method not only\nenables rapid and accurate segmentation but also facilitates an unprecedented\nlevel of data analysis, significantly improving the statistical representation\nof grain boundary networks, making it suitable for a range of disciplines where\nprecise segmentation of interconnected line networks is essential.",
        "positive": "Full-plane persistent spin textures with cubic order intrinsic and\n  anisotropic band splitting in bulk Lead-free materials: Spin-orbit coupling (SOC) effects occurring in noncentrosymmetric materials\nare known to be responsible for nontrivial spin configurations and a number of\nemergent physical phenomena such as electrical control of spin degrees of\nfreedom and spin-to-charge conversion. The materials preserving a uniform spin\nconfiguration in the momentum-space, known as persistent spin texture (PST),\nprovide long carrier spin lifetimes through persistent spin helix (PSH)\nmechanism. However, most of the PST studied till now are attributed to the\nlinear in \\textbf{\\textit{k}} splitting and cease to exist locally around\ncertain high-symmetry-point of first Brillouin Zone (FBZ). The persistent spin\ntextures with purely cubic spin splittings have drawn attention owing to unique\nbenefits in spin transport. Here, by using the relativistic first-principles\ncalculations supplemented with \\textbf{\\textit{k.p}} analysis, we report the\nemergence of purely cubic splitting (PCS) belonging to $D_{3h}$ point group,\nwhich is enforced by in-plane mirror and three-fold rotation operations. In\naddition, the in-plane mirror symmetry operation sustains the PST in larger\nregion (i.e. full planes) of FBZ alongside giant spin splitting. Our results\nalso demonstrate how application of uniaxial strain could be envisaged to tune\nthe magnitude of the PCS, preserving the PST. The observed PSTs provide a route\nto non-dephasing spin transport with larger spin-Hall conductivity, thus\noffering a promising platform for future spintronics devices."
    },
    {
        "anchor": "Magnetic properties of single atoms of Fe and Co on Ir(111) and Pt(111): In using the fully relativistic versions of the Embedded Cluster and Screened\nKorringa-Kohn-Rostoker methods for semi-infinite systems the magnetic\nproperties of single adatoms of Fe and Co on Ir(111) and Pt(111) are studied.\nIt is found that for Pt(111) Fe and Co adatoms are strongly perpendicularly\noriented, while on Ir(111) the orientation of the magnetization is only\nout-of-plane for a Co adatom, for an Fe adatom it is in-plane. For comparison\nalso the so-called band energy parts of the anisotropy energy of a single layer\nof Fe and Co on these two substrates are shown. The obtained results are\ncompared to recent experimental studies using e.g. the spin-polarized STM\ntechnique.",
        "positive": "Strain-induced large band-gap topological insulator in a new stable\n  silicon allotrope: dumbbell silicene: By the generalized gradient approximation in framewok of density functional\ntheory, we investigate a 2D topological insulator of new silicon allotrope\n(call dumbbell silicene synthesized recently by Cahangirov et al) through\ntuning external compression strain, and find a topological quantum phase\ntransition from normal to topological insulator, i.e., the dumbbell silicene\ncan turn a two-dimensional topological insulator with an inverted band gap. The\nobtained maximum topological nontrivial band gap about 12 meV under isotropic\nstrain is much larger than that for previous silicene, and can be further\nimproved to 36 meV by tuning anisotropic strain, which is sufficiently large to\nrealize quantum spin Hall effect even at room-temperature, and thus is\nbeneficial to the fabrication of high-speed spintronics devices. Furthermore,\nwe confirm that the boron nitride sheet is an ideal substrate for the\nexperimental realization of the dumbbell silicene under external strain,\nmaintaining its nontrivial topology. These properties make the two-dimensional\ndumbbell silicene a good platform to study novel quantum states of matter,\nshowing great potential for future applications in modern silicon-based\nmicroelectronics industry."
    },
    {
        "anchor": "DNA-Au (111) Interactions and Transverse Charge Transport Properties for\n  DNA-Based Electronic Devices: DNAs charge transfer and self-assembly characteristics have made it a\nhallmark of molecular electronics for the past two decades. A fast and\nefficient charge transfer mechanism with programmable properties using DNA\nnanostructures is required for DNA-based nanoelectronics applications and\ndevices. The ability to integrate DNA with inorganic substrates becomes\ncritical in this process. Such integrations may effect the conformation of DNA,\naltering the charge transport properties. Thus, using molecular dynamics\nsimulations and first-principles calculations in conjunction with Greens\nfunction approach, we explore the impact of Au (111) substrate on the\nconformation of DNA and analyze its effect on the charge transport. Our results\nindicate that DNA sequence, leading its molecular conformation on Au substrate,\nis critical to engineer charge transport properties. We demonstrate that DNA\ncan fluctuate on a gold substrate, sampling various distinct conformations over\ntime. The energy levels, spatial locations of molecular orbitals and the DNA/Au\ncontact atoms can differ between these distinct conformations. Depending on the\nsequence, at HOMO, the charge transmission differs up to 60 times between the\ntop ten conformations. We demonstrate that the relative positions of the\nnucleobases are critical in determining the conformations and the coupling\nbetween orbitals. We anticipate these results can be extended to other\ninorganic surfaces and pave the way for understanding DNA inorganic interface\ninteraction for future DNA-based electronic devices.",
        "positive": "Towards the computational experiment: We give a brief account of the current limitations and possibilities in the\nfield of computational simulation of materials. We then focus on the effect\nthat the emergence of machine learning interatomic potentials is having on the\nfield and how it will affect its evolution in the near future."
    },
    {
        "anchor": "Surface morphology, structure and transport property of NaxCoO2 thin\n  films grown by pulsed laser deposition: In this paper, we report the growth of NaxCoO2 thin films by pulsed-laser\ndeposition (PLD). It is shown that the concentration of sodium is very\nsensitive to the substrate temperature and the target-substrate distance due to\nthe evaporation of sodium during the deposition. alpha prime-phase Na0.75CoO2\nand gamma- phase Na0.71CoO2 thin films can be obtained with different\nconditions. Correspondingly, the surface morphology of the films changes from\nflake-like to particle-like. The temperature dependence of resistivity for the\nfilms prepared with the optimal condition shows metallic behavior, consistent\nwith the data of NaxCoO2 single crystals. This work demonstrates that PLD is a\npromising technique to get high quality NaxCoO2 thin films.",
        "positive": "Microscopic mechanism for mechanical polishing of diamond (110) surfaces: Mechanically induced degradation of diamond, as occurs during polishing, is\nstudied using total--energy pseudopotential calculations. The strong asymmetry\nin the rate of polishing between different directions on the diamond (110)\nsurface is explained in terms of an atomistic mechanism for nano--groove\nformation. The post--polishing surface morphology and the nature of the\npolishing residue predicted by this mechanism are consistent with experimental\nevidence."
    },
    {
        "anchor": "A hybrid functional for the exchange-correlation kernel in\n  time-dependent density functional theory: A review of the approximations in any time-dependent density functional\ncalculation of excitation energies is given. The single-pole approximation for\nthe susceptibility is used to understand errors in popular approximations for\nthe exchange-correlation kernel. A new hybrid of exact exchange and adiabatic\nlocal density approximation is proposed and tested on the He and Be atoms.",
        "positive": "Electronic structure of Co_xTiSe_2 and Cr_xTiSe_2: The results of investigations of intercalated compounds Cr_xTiSe_2 and\nCo_xTiSe_2 by X-ray photoelectron spectroscopy (XPS) and X-ray emission\nspectroscopy (XES) are presented. The data obtained are compared with\ntheoretical results of spin-polarized band structure calculations. A good\nagreement between theoretical and experimental data for the electronic\nstructure of the investigated materials has been observed. The interplay\nbetween the M3d--Ti3d hybridization (M=Cr, Co) and the magnetic moment at the M\nsite is discussed. A 0.9 eV large splitting of the core Cr2p{3/2} level was\nobserved, which reveals a strong exchange magnetic interaction of 3d-2p\nelectrons of Cr. In the case of a strong localization of the Cr3d electrons\n(for x<0.25), the broadening of the CrL spectra into the region of the states\nabove the nominal Fermi level was observed and attributed to X-ray re-emission.\nThe measured kinetic properties are in good accordance with spectral\ninvestigations and band calculation results."
    },
    {
        "anchor": "Ferroelectric Switching Pathways and Domain Structure of\n  SrBi$_2$(Ta,Nb)$_2$O$_9$ from First Principles: Several families of layered perovskite oxide ferroelectrics exhibit a\ncoupling between polarization and structural order parameters, such as\noctahedral rotation distortions. This coupling provides opportunities for novel\nelectric field-based manipulation of material properties, and also stabilizes\ncomplex domain patterns and domain wall vortices. Amongst layered perovskites\nwith such coupled orders, the Aurivillius-phase oxides SrBi$_2B_2$O$_9$\n($B$=Ta, Nb) are well-known for their excellent room temperature ferroelectric\nperformance. This work combines group theoretic analysis with density\nfunctional theory calculations to examine the ferroelectric switching processes\nof SrBi$_2B_2$O$_9$. Low-energy two-step ferroelectric switching paths are\nidentified, with polarization reversal facilitated by structural order\nparameter rotations. Analysis of the domain structure reveals how the relative\nenergetics of the coupled order parameters translates into a network of several\ndistinct domain wall types linked by domain wall vortex structures. Comparisons\nare made between the ferroelectric switching and domain structure of\nSrBi$_2B_2$O$_9$ and those of the layered $n$=2 Ruddlesden-Popper hybrid\nimproper ferroelectrics. The results provide new insight into how ferroelectric\nproperties may be optimized by engineering the complex crystal structures of\nAurivllius-phase oxides.",
        "positive": "First-Principles Prediction of Electronic Transport in Experimental\n  Semiconductor Heterostructures via Physics-Based Machine Learning: First-principles techniques for electronic transport property prediction have\nseen rapid progress in recent years. However, it remains a challenge to model\nheterostructures incorporating variability due to fabrication processes.\nMachine-learning (ML)-based materials informatics approaches (MI) are\nincreasingly used to accelerate design and discovery of new materials with\ntargeted properties, and extend the applicability of first-principles\ntechniques to larger systems. However, few studies exploited MI to learn\nelectronic structure properties and use the knowledge to predict the respective\ntransport coefficients. In this work, we propose an\nelectronic-transport-informatics (ETI) framework that trains on ab initio\nmodels of small systems and predicts thermopower of silicon/germanium\nheterostructures beyond the length-scale accessible with first-principles\ntechniques, matching measured data. We demonstrate application of MI to extract\nimportant physics that determines electronic transport in semiconductor\nheterostructures, breaking from combinatorial strategies pursued especially for\nthermoelectric materials. We anticipate that ETI would have broad applicability\nto diverse materials classes."
    },
    {
        "anchor": "Approaching Ferrite-Based Exchange-Coupled Nanocomposites as Permanent\n  Magnets: During the past decade, CoFe2O4 (hard)/Co-Fe alloy (soft) magnetic\nnanocomposites have been routinely prepared by partial reduction of CoFe2O4\nnanoparticles. Monoxide (i.e., FeO or CoO) has often been detected as a\nbyproduct of the reduction, although it remains unclear whether the formation\nof this phase occurs during the reduction itself or at a later stage. Here, a\nnovel reaction cell was designed to monitor the reduction in situ using\nsynchrotron powder X-ray diffraction (PXRD). Sequential Rietveld refinements of\nthe in situ data yielded time-resolved information on the sample composition\nand confirmed that the monoxide is generated as an intermediate phase. The\nmacroscopic magnetic properties of samples at different reduction stages were\nmeasured by means of vibrating sample magnetometry (VSM), revealing a magnetic\nsoftening with increasing soft phase content, which was too pronounced to be\nexclusively explained by the introduction of soft material in the system. The\nelemental compositions of the constituent phases were obtained from joint\nRietveld refinements of ex situ high-resolution PXRD and neutron powder\ndiffraction (NPD) data. It was found that the alloy has a tendency to emerge in\na Co-rich form, inducing a Co deficiency on the remaining spinel phase, which\ncan explain the early softening of the magnetic material.",
        "positive": "Inevitable Si surface passivation prior to III-V/Si epitaxy: A strong\n  impact on wetting properties: Here, we quantitatively estimate the impact of the inevitable Si surface\npassivation prior to III-V/Si hetero-epitaxy on the surface energy of the Si\ninitial substrate, and explore its consequences for the description of wetting\nproperties. Density Functional Theory is used to determine absolute surface\nenergies of P- and Ga-passivated Si surfaces and their dependencies with the\nchemical potential. Especially, we show that, while a ~90 meV/$\\r{A}^2$ surface\nenergy is usually considered for the nude Si surface, surface passivation by\nGa- or P- atoms leads to a strong stabilization of the surface, with a surface\nenergy in the [50-75 meV/$\\r{A}^2$] range. The all-ab initio analysis of the\nwetting properties indicate that a complete wetting situation would become\npossible only if the initial passivated Si surface could be destabilized by at\nleast 15 meV/$\\r{A}^2$ or if the III-V (001) surface could be stabilized by the\nsame amount."
    },
    {
        "anchor": "Chirality-induced asymmetric magnetic nucleation in Pt/Co/AlOx ultrathin\n  microstructures: The nucleation of reversed magnetic domains in Pt/Co/AlO$_{x}$\nmicrostructures with perpendicular anisotropy was studied experimentally in the\npresence of an in-plane magnetic field. For large enough in-plane field,\nnucleation was observed preferentially at an edge of the sample normal to this\nfield. The position at which nucleation takes place was observed to depend in a\nchiral way on the initial magnetization and applied field directions. An\nexplanation of these results is proposed, based on the existence of a sizable\nDzyaloshinskii-Moriya interaction in this sample. Another consequence of this\ninteraction is that the energy of domain walls can become negative for in-plane\nfields smaller than the effective anisotropy field.",
        "positive": "Nutational switching in ferromagnets and antiferromagnets: It was demonstrated recently that on ultrashort time scales magnetization\ndynamics does not only exhibit precession but also nutation. Here, we\ninvestigate how nutation can contribute to spin switching leading towards\nultrafast data writing. We use analytic theory and atomistic spin simulations\nto discuss the behavior of ferromagnets and antiferromagnets in high-frequency\nmagnetic fields. In ferromagnets, linearly polarized fields align the\nmagnetization perpendicular to the external field, enabling $90^{\\circ}$\nswitching. For circularly polarized fields in the $xy$ plane, the magnetization\ntilts to the $z$ direction. During this tilting, it rotates around the $z$\naxis, allowing $180^{\\circ}$ switching. In antiferromagnets, external fields\nwith frequencies higher than the nutation frequency align the order parameter\nparallel to the field direction, while for lower frequencies it is oriented\nperpendicular to the field. The switching frequency increases with the magnetic\nfield strength, and it deviates from the Larmor frequency, making it possible\nto outpace precessional switching in high magnetic fields."
    },
    {
        "anchor": "One directional Polarized Neutron Reflectometry with optimized reference\n  layer method: In the past decade, several neutron reflectometry methods for determining the\nmodulus and phase of the complex reflection coefficient of an unknown\nmultilayer thin film have been worked out among which the method of variation\nof surroundings and reference layers are of highest interest. These methods\nwere later modified for measurement of the polarization of the reflected beam\ninstead of the measurement of the intensities. In their new architecture, these\nmethods not only suffered from the necessity of change of experimental setup,\nbut also another difficulty was added to their experimental implementations.\nThis deficiency was related to the limitations of the technology of the neutron\nreflectometers that could only measure the polarization of the reflected\nneutrons in the same direction as the polarization of the incident beam. As the\ninstruments are limited, the theory has to be optimized so that the experiment\ncould be performed. In a recent work, we developed the method of variation of\nsurroundings for one directional polarization analysis. In this new work, the\nmethod of reference layer with polarization analysis has been optimized to\ndetermine the phase and modulus of the unknown film with measurement of the\npolarization of the reflected neutrons in the same direction as the\npolarization of the incident beam.",
        "positive": "Green reconstruction of MIL-100 (Fe) in water for high crystallinity and\n  enhanced guest encapsulation: MIL-100 (Fe) is a highly porous metal-organic framework (MOF), considered as\na promising carrier for drug delivery, and for gas separation and capture\napplications. However, this functional material suffers from elaborated and\ntoxic synthesis that may hinder its biomedical use and large-scale production\nto afford commercial applications. Herein, we report a green mechanochemical\nwater immersion approach to yield highly crystalline MIL100 (Fe) material.\nSubsequently, we have harnessed this strategy for facile fabrication of\ndrug@MOF composite systems, comprising (guests) 5-fluorouracil, caffeine, or\naspirin encapsulated in the pores of (host) MIL-100 (Fe). Inelastic neutron\nscattering was uniquely used to probe the guest host interactions arising from\npore confinement of the drug molecules, giving additional insights into the\nreconstruction mechanism. Our results pave the way to the green production of\nMIL type materials and bespoke guest-encapsulated composites by minimizing the\nuse of toxic chemicals, whilst enhancing energy efficiency and material's life\ncycle central to biotechnological applications."
    },
    {
        "anchor": "Effects of surface chemical modifications on the adhesion of metallic\n  interfaces. An high-throughput analysis: Chemical interactions between two surfaces in contact play a crucial role in\ndetermining the mechanical and tribological behavior of solid interfaces. These\ninteractions can be quantified via adhesion energy, that is a measure of the\nstrength by which two surfaces bind together. Several works in literature\nreport how the presence of chemisorbed atoms at homo- and heterogeneous\nsolid-solid interfaces drastically change their proprieties. A precise\nevaluation of how different species at solid contacts modulates their adhesion\nwould be extremely beneficial for a range of different technological fields:\nfrom metallurgy to nuclear fusion. In this work we have used and\nhigh-throughput approach to systematically explore the effects of the presence\nof non-metallic elements, at different concentrations, on the adsorption and\nadhesion energies of different homogeneous metallic interfaces. Together with\nthe databases for the adsorption and the adhesion energies, we calculated\nseveral other properties such as the charge transferred at the interface, the\nd-band edge shift for the substrate the Bond order and the interfacial density\nredistribution for the hundreds of systems analyzed. These values were used to\ndefine different trends with respect to chemical and concentration parameters\nthat could be useful for the development of engineered interfaces with selected\nproperties. In particular we noticed how the substrate with low filling of\nd-band are the most prone to adsorb ad-atoms and how the adsorption of almost\nall non-metallic elements decreases the adhesion energy of solid interfaces,\nparticularly in the case of Fluorine. Carbon and Boron were the only two\nad-atoms species that showed an opposite trend increasing the adhesion energy\ninstead.",
        "positive": "Chiral Topological Insulators, Superconductors and other competing\n  orders in three dimensions: We discuss the proximate phases of a three-dimensional system with Dirac-like\ndispersion. Using the cubic lattice with plaquette $\\pi$-flux as a model, we\nfind, among others phases, a chiral topological insulator and singlet\ntopological superconductor. While the former requires a special \"chiral\"\nsymmetry, the latter is stable as long as time reversal and SU(2) spin rotation\nsymmetry are present. These phases are characterized by stable surface Dirac\nfermion modes, and by an integer topological invariant in the bulk. The key\nfeatures of these phases are readily understood in a two dimensional limit with\nan appropriate pairing of Dirac nodes between layers. This Dirac node-pairing\npicture is also shown to apply to $Z_2$ topological insulators protected by\ntime-reversal symmetry (TRS). The nature of point-like topological defects in\nthese phases is also investigated, revealing an interesting duality relation\nbetween these topological phases and the Neel phase."
    },
    {
        "anchor": "Theoretical Study of Corundum as an Ideal Gate Dielectric Material for\n  Graphene Transistors: Using physical insights and advanced first-principles calculations, we\nsuggest that corundum is an ideal gate dielectric material for graphene\ntransistors. Clean interface exists between graphene and Al-terminated (or\nhydroxylated) Al2O3 and the valence band offsets for these systems are large\nenough to create injection barrier. Remarkably, a band gap of {\\guillemotright}\n180 meV can be induced in graphene layer adsorbed on Al-terminated surface,\nwhich could realize large ON/OFF ratio and high carrier mobility in graphene\ntransistors without additional band gap engineering and significant reduction\nof transport properties. Moreover, the band gaps of graphene/Al2O3 system could\nbe tuned by an external electric field for practical applications.",
        "positive": "High-contrast modulation of light with light by control of surface\n  plasmon polariton wave coupling: We have demonstrated a new mechanism for modulating light with light by\ncontrolling the efficiency with which light is coupled into a plasmon polariton\nwave. An optical fluence of 15 mJ/cm^2 in the control channel is sufficient to\nachieve nearly a 10-fold intensity modulation of the signal beam reflected from\na Glass/MgF_2/Ga structure. The mechanism depends on a nanoscale light-induced\nstructural transformation in the gallium layer and has transient switching\ntimes of the order of a few tens of nanoseconds. It offers high modulation\ncontrast for signals in the visible and near infrared spectral ranges."
    },
    {
        "anchor": "Atomic Structure of Graphene on SiO2: We employ scanning probe microscopy to reveal atomic structures and nanoscale\nmorphology of graphene-based electronic devices (i.e. a graphene sheet\nsupported by an insulating silicon dioxide substrate) for the first time.\nAtomic resolution STM images reveal the presence of a strong spatially\ndependent perturbation, which breaks the hexagonal lattice symmetry of the\ngraphitic lattice. Structural corrugations of the graphene sheet partially\nconform to the underlying silicon oxide substrate. These effects are obscured\nor modified on graphene devices processed with normal lithographic methods, as\nthey are covered with a layer of photoresist residue. We enable our experiments\nby a novel cleaning process to produce atomically-clean graphene sheets.",
        "positive": "Large scale GW calculations: We present GW calculations of molecules, ordered and disordered solids and\ninterfaces, which employ an efficient contour deformation technique for\nfrequency integration, and do not require the explicit evaluation of virtual\nelectronic states, nor the inversion of dielectric matrices. We also present a\nparallel implementation of the algorithm which takes advantage of separable\nexpressions of both the single particle Green's function and the screened\nCoulomb interaction. The method can be used starting from density functional\ntheory calculations performed with semi-local or hybrid functionals. We applied\nthe newly developed technique to GW calculations of systems of unprecedented\nsize, including water/semiconductor interfaces with thousands of electrons."
    },
    {
        "anchor": "Topological layered n-type thermoelectrics based on bismuth telluride\n  solid solutions: In topological n-type thermoelectrics based on $Bi_{2}Te_{3}$ with atomic\nsubstitutions Bi $\\rightarrow$ In, Te $\\rightarrow$ Se, S, the morphology and\nthe surface states of Dirac fermions on the interlayer (0001) surface of van\nder Waals were studied by scanning tunneling microscopy and spectroscopy\n(STM/STS) techniques. By the STM method, the dark and light spots on the\nsurface were found, which intensities depend on the composition and\nthermoelectric properties of solid solutions. The observed surface morphology\nfeatures in the solid solutions are explained by distortions of surface\nelectronic states originated by atomic substitutions, influence of doping\nimpurity, and formation of structural defects. Fast Fourier transform (FFT) of\nthe morphology STM images of the (0001) surface were used to obtain the\ninterference patterns of the quasiparticles excitation caused by surface\nelectrons scattering by defects. The Dirac point energy and its fluctuations,\npeak energies of surface defects, the positions of the valence and conduction\nband edges, and the energy gap were determined from an analysis of tunneling\nspectra. A correlation between the parameters of surface states of Dirac\nfermions and thermoelectric properties was found. Thus, a contribution of the\nfermions surface states increases with rise of the surface concentration in\nsolid solutions with high power factor, and the largest concentration value was\nobserved in the $Bi_{1.98}In_{0.02}Te_{2.85}Se_{0.15}$ composition. The\ndependences of Fermi energy on the wave vector for different solid solutions\nare described by a set of Dirac cone sections, which are close within the\nlimits of the fluctuations of the Dirac point energy that explained by weak\nchanges of the Fermi velocity in the compositions at studied atomic\nsubstitutions in the bismuth telluride sublattices.",
        "positive": "Potential ring of Dirac nodes in a new polymorph of Ca$_3$P$_2$: We report the crystal structure of a new polymorph of Ca$_3$P$_2$, and an\nanalysis of its electronic structure. The crystal structure was determined\nthrough Rietveld refinements of powder synchrotron x-ray diffraction data.\nCa$_3$P$_2$ is found to be a variant of the Mn$_5$Si$_3$ structure type, with a\nCa ion deficiency compared to the ideal 5:3 stoichiometry to yield a\ncharge-balanced compound. We also report the observation of a secondary phase,\nCa$_5$P$_3$H, in which the Ca and P sites are fully occupied and the presence\nof interstitial hydride ions creates a closed-shell electron-precise compound.\nWe show via electronic structure calculations of Ca$_3$P$_2$ that the compound\nis stabilized by a gap in the density of states compared to the hypothetical\ncompound Ca$_5$P$_3$. Moreover, the calculated band structure of Ca$_3$P$_2$\nindicates that it should be a three-dimensional Dirac semimetal with a highly\nunusual ring of Dirac nodes at the Fermi level. The Dirac states are protected\nagainst gap opening by a mirror plane in a manner analogous to graphene. The\nresults suggest that further study of the electronic properties of Ca$_3$P$_2$\nwill be of interest."
    },
    {
        "anchor": "Control of Propagating Spin Waves via Spin Transfer Torque in a Metallic\n  Bilayer Waveguide: We investigate the effect of a direct current on propagating spin waves in a\nCoFeB/Ta bilayer structure. Using the micro-Brillouin light scattering\ntechnique, we observe that the spin wave amplitude may be attenuated or\namplified depending on the direction of the current and the applied magnetic\nfield. Our work suggests an effective approach for electrically controlling the\npropagation of spin waves in a magnetic waveguide and may be useful in a number\nof applications such as phase locked nano-oscillators and hybrid information\nprocessing devices.",
        "positive": "Irradiation-induced strain localization and strain burst suppression\n  investigated by microcompression and concurrent acoustic emission experiments: Plastic deformation of microsamples is characterised by large intermittent\nstrain bursts caused by dislocation avalanches. Here we investigate how ion\nirradiation affects this phenomenon during single slip single crystal\nplasticity. To this end, in situ compression of Zn micropillars oriented for\nbasal slip was carried out in a SEM. The unique experimental setup also allowed\nthe concurrent recording of the acoustic emission (AE) signals emitted from the\nsample during deformation. It was shown that irradiation introduced a\nhomogeneous distribution of basal dislocation loops that lead to hardening of\nthe sample as well as strain softening due to dislocation channeling at larger\nstrains. With the used deformation protocol strain burst sizes were found to be\ndecreased due to channeling. The concurrently recorded AE events were\ncorrelated with the strain bursts and their analysis provided additional\ninformation of the details of collective dislocation dynamics. It was found\nthat the rate of AE events decreased significantly upon irradiation, however,\nother statistical properties did not change. This was attributed to the\nappearance of a new type of plastic events dominated by short-range\ndislocation-obstacle interactions that cannot be detected by AE sensors."
    },
    {
        "anchor": "Band alignment and directional stability in abrupt and polar-compensated\n  Si/ZnS interface calculations: We perform a first principles investigation of Si/ZnS interface properties\nfor the [111], [100], and [110] directions, including single-substitution\npolar-compensated interfaces. The asymmetry of general interface directions\nposes known challenges for standard methods of calculation: a multiplicity of\ninterface distinctions, artificial electric fields, and indeterminacy of\norientation stability. By placing each distinct interface in a variety of\nsupercell environments, we demonstrate that the spread of both band offsets and\ninterface enthalpies is acceptably small for reasonable cell lengths, removing\nthe need for corrections involving inappropriate assumptions or computationally\nexpensive structures. Both the orientation and the ionic character of abrupt\n(111) zinc blende interfaces are shown to affect band alignment and interface\nenthalpy. We find that the band offsets for the compensated and abrupt (111)\nand (100) interfaces lie on a strongly bimodal distribution of total width\ngreater than 1.2 eV, while the (110) band offset lies near the distribution\nmidpoint. The midpoint agrees with previous experiments on (100) interfaces,\nbut only one peak of the distribution agrees with (111) interface experiments,\nindicating that the grown macroscopic (111) interfaces had significant\nselectivity among the possible microscopic interfaces. The polar-compensated\ninterfaces are shown to be more stable than the corresponding abrupt interfaces\nover most growth conditions.",
        "positive": "Oxide perovskite BaSnO3: A promising high-temperature thermoelectric\n  material for transparent conducting oxides: The new technology of energy conversion must be developed to ensure energy\nsustainability. Thermoelectric (TE) materials provide an effective means to\nsolve the energy crisis. As a potential TE candidate, the TE properties of\nperovskite have received extensively attention. We here investigate the TE\ntransport properties of the transparent conducting oxide (TCO) BaSnO3 by\nfirst-principles calculations. We find that the BaSnO3 perovskite exhibits\noutstanding dynamic and thermal stabilities, which provide excellent electronic\nand thermal transport properties simultaneously. These properties contribute to\nthe remarkable Seebeck coefficient and power factor, which gives rise to the ZT\nof n-0.37 and p-1.52 at 900 K. Additionally, doping and nanostructure open\nprospects for effectively improving the TE properties of BaSnO3. Our work\nprovides a basis for further optimizing the TE transport properties of cubic\nBaSnO3 and may have worthwhile practical significance for applying cubic\nperovskite to the high-temperature thermoelectric field."
    },
    {
        "anchor": "Royal Society Inaugural Article Perspective: Multiferroics Beyond\n  Electric-Field Control of Magnetism: Multiferroic materials, with their combined and coupled magnetism and\nferroelectricity, providea playground for studying new physics and chemistry as\nwell as a platform for development ofnovel devices and technologies. Based on\nmy July 2017 Royal Society Inaugural Lecture, I review recent progress and\npropose future directions in the fundamentals and applications of\nmultiferroics, with a focus on unanticipated developments outside of the core\nactivity of electric-field control of magnetism.",
        "positive": "Quantum Monte Carlo study of Doppler broadening of positron annihilation\n  radiation in semiconductors and insulators: Positron annihilation in solid state matter can be utilized to detect and\nidentify open-volume defects. The momentum distribution of the annihilation\nradiation is an important observable in positron-based measurements, and can\nreveal information on the chemical surroundings of the defect sites. In this\nwork we present a variational quantum Monte Carlo method for simulation of the\nmomentum densities of annihilating electron-positron pairs in semiconductors\nand insulators. We study finite-size effects, effects of lattice vibrations,\nand different levels of trial wave functions. Small simulation cells and simple\nwave function forms are found to be sufficient for accurate calculations in\nsimulation of pristine lattices, enabling cheap accumulation of results. We\ncompare calculated predictions of the Doppler broadening of the 511-keV\n2{\\gamma} annihilation line of the in aluminium nitride and silicon against\nexperimental data measured from reference samples. Our results achieve better\nagreement with experiments in the these materials than conventional\nstate-of-the-art methods, and proves that direct modeling of the\nelectron-positron correlations is important for a supporting theory of positron\nannihilation sprectroscopies"
    },
    {
        "anchor": "Effects of Li doping on H-diffusion in MgH$_2$: a first-principles study: The effects of Li doping in MgH$_2$ on H-diffusion process are investigated,\nusing first-principles calculations. We have identified two key effects: (1)\nThe concentration of H vacancy in the $+1$ charge state (V$_H^{+1}$) can\nincrease by several orders of magnitude upon Li doping, which significantly\nincreases the vacancy mediated H diffusion rate. It is caused by the preferred\ncharge states of substitutional Li in the $-1$ state (Li$_{Mg}^{-1}$) and of\ninterstitial Li in the $+1$ state (Li$_i^{+1}$), which indirectly reduce the\nformation energy of V$_H^{+1}$ by up to 0.39 eV depending on the position of\nFermi energy. (2) The interaction between V$_H^{+1}$ and Li$_{Mg}^{-1}$ is\nfound to be attractive with a binding energy of 0.55 eV, which immobilizes the\nV$_H^{+1}$ next to Li$_{Mg}^{-1}$ at high Li doping concentration. As a result,\nthe competition between these two effects leads to large enhancement of H\ndiffusion at low Li doping concentration due to the increased H-vacancy\nconcentration, but only limited enhancement at high Li concentration due to the\nimmobilization of H vacancies by too many Li.",
        "positive": "Enabling discovery of materials through enhanced generalisability of\n  deep learning models: The road towards the discovery of new, useful materials is full of\nimperfections. Machine learning, which is currently the power horse of material\ndiscovery when it works in concert with density functional theory, has been\nable to accelerate the discovery of new materials for various applications by\nlearning the properties of known, stable materials to infer the properties of\nunknown, deformed materials. Physics-informed machine learning (PIML) is\nparticularly believed to bridge the gap between known materials and the\nvirtually infinite space of crystal structures with imperfections such as\ndefects, grain boundaries, composition disorders and others. State of the art\nPIML models struggle to bridge this gap, however. In this work we show that a\ncritical correction of the physics underpinning a PIML, our direct integration\nof external potential (DIEP) method, which mimics the integration of the\nexternal potential term in typical density functional theory calculations,\nimproves the generalisability of the model to a range of imperfect structures,\nincluding diamond defects. DIEP has the potential of enhancing the accuracy of\npotential energy surface prediction, which can accelarate structure discovery."
    },
    {
        "anchor": "Atomic Layer Epitaxy of Kagome Magnet Fe${_3}$Sn${_2}$ and Sn-modulated\n  Heterostructures: Magnetic materials with kagome crystal structure exhibit rich physics such as\nfrustrated magnetism, skyrmion formation, topological flat bands, and\nDirac/Weyl points. Until recently, most studies on kagome magnets have been\nperformed on bulk crystals or polycrystalline films. Here we report the atomic\nlayer molecular beam epitaxy synthesis of high-quality thin films of\ntopological kagome magnet Fe${_3}$Sn${_2}$. Structural and magnetic\ncharacterization of Fe${_3}$Sn${_2}$ on epitaxial Pt(111) identifies highly\nordered films with c-plane orientation and an in-plane magnetic easy axis.\nStudies of the local magnetic structure by anomalous Nernst effect imaging\nreveals in-plane oriented micrometer size domains. Superlattice structures\nconsisting of Fe${_3}$Sn${_2}$ and Fe${_3}$Sn are also synthesized by atomic\nlayer molecular beam epitaxy, demonstrating the ability to modulate the sample\nstructure at the atomic level. The realization of high-quality films by atomic\nlayer molecular beam epitaxy opens the door to explore the rich physics of this\nsystem and investigate novel spintronic phenomena by interfacing\nFe${_3}$Sn${_2}$ with other materials.",
        "positive": "Topologically protected surface states in a centrosymmetric\n  superconductor beta-PdBi2: The topological aspects of electrons in solids emerge in realistic matters as\nrepresented by topological insulators. They are expected to show a variety of\nnew magneto-electric phenomena, and especially the ones hosting\nsuperconductivity are strongly desired as the candidate for topological\nsuperconductors (TSC). Possible TSC materials have been mostly developed by\nintroducing carriers into topological insulators, nevertheless, those\nexhibiting indisputable superconductivity free from inhomogeneity are very few.\nHere we report on the observation of topologically-protected surface states in\na centrosymmetric layered superconductor, beta-PdBi2, by utilizing spin- and\nangle-resolved photoemission spectroscopy. Besides the bulk bands, several\nsurface bands, some of which crossing the Fermi level, are clearly observed\nwith symmetrically allowed in-plane spin-polarizations. These surface states\nare precisely evaluated to be topological, based on the Z2 invariant analysis\nin analogy to 3-dimensional strong topological insulators. beta-PdBi2 may offer\na TSC realized without any carrier-doping or applying pressure, i.e. a solid\nstage to investigate the topological aspect in the superconducting condensate."
    },
    {
        "anchor": "Mechanisms of shock-induced initiation at micro-scale defects in\n  energetic crystal-binder systems: Crystals of energetic materials, such as HMX, embedded in plastic binders are\nthe building blocks of plastic-bonded explosives. Such heterogeneous energetic\nmaterials contain microstructural features such as sharp corners, interfaces\nbetween crystal and binder, intra- and extra-granular voids, and other defects.\nEnergy localization or hotspots arise during shock interaction with the\nmicrostructural heterogeneities, leading to the initiation of PBXs. In this\npaper, high-resolution numerical simulations are performed to elucidate the\nmechanistic details of shock-induced initiation in a PBX; we examine four\ndifferent mechanisms: Shock-focusing at sharp corners or edges and its\ndependency on the shape of the crystal, and the strength of the applied shock;\ndebonding between crystal and binder interfaces; collapse of voids in the\nbinder located near an HMX crystal; and the collapse of voids within HMX\ncrystals. Insights are obtained into the relative contributions of these\nmechanisms to the ignition and growth of hotspots. Understanding these\nmechanisms of energy localization and their relative importance for hotspot\nformation and initiation sensitivity of PBXs will aid in the design of\nenergetic material-driven systems with controlled sensitivity, to prevent\naccidental initiation and ensure reliable performance.",
        "positive": "Atomic bonding and electrical characteristics of metallic and\n  semi-metallic elements: In this paper, we use density functional theory to calculate the electronic\nstructure and properties of 46 metallic and semi-metallic elements. The binding\nenergy and bond charge model (BBC) model is combined with the tight binding and\ndensity functional tight binding approaches to obtain quantitative information\nabout atomic bonding at the atomic scale and to understand the contributions\nand effects of deformation energy density, energy shifts, and atomic bonding on\nthe Hamiltonian."
    },
    {
        "anchor": "Low temperature and high magnetic field performance of a commercial\n  piezo-actuator probed $via$ laser interferometry: The advances in the fields of scanning probe microscopy, scanning tunneling\nspectroscopy, point contact spectroscopy and point contact Andreev reflection\nspectroscopy to study the properties of conventional and quantum materials at\ncryogenic conditions have prompted the development of nanopositioners and\nnanoscanners with enhanced spatial resolution. Piezoelectric-actuator stacks as\nnanopositioners with working strokes $>100~\\mu\\mathrm{m}$ and positioning\nresolution $\\sim$(1-10) nm are desirable for both basic research and industrial\napplications. However, information on the performance of most commercial\npiezoelectric-actuators in cryogenic environment and in the presence of\nmagnetic fields in excess of 5\\,T is generally not available. In particular,\nthe magnitude, rate and the associated hysteresis of the piezo-displacement at\ncryogenic temperatures are the most relevant parameters that determine whether\na particular piezoelectric-actuator can be used as a nanopositioner. Here, the\ndesign and realization of an experimental set-up based on interferometric\ntechniques to characterize a commercial piezoelectric-actuator over a\ntemperature range of $2~\\mathrm{K}\\leq{T}\\leq260~\\mathrm{K}$ and magnetic\nfields up to 6\\,T is presented. The studied piezoelectric-actuator has a\nmaximum displacement of $30~\\mu\\mathrm{m}$ at room temperature for a maximum\ndriving voltage of 75\\,V, which reduces to $1.2~\\mu\\mathrm{m}$ with an absolute\nhysteresis of $\\left(9.1\\pm3.3\\right)~\\mathrm{nm}$ at $T=2\\,\\mathrm{K}$. The\nmagnetic field is shown to have no substantial effect on the piezo properties\nof the studied piezoelectric-actuator stack.",
        "positive": "Structural evolution of the elastic properties in nano-structured AlN\n  film: A study of the transverse acoustic phonons on nano-structured AlN films has\nbeen carried out by using high-resolution micro-Brillouin spectroscopy. Dense\nfilms have been deposited by radio frequency (r.f.) magnetron sputtering under\nultra high vacuum at room temperature. Films with different morphologies were\nprepared and investigated by transmission electron microscopy and Brillouin\nSpectroscopy (equiaxed nano-sized, nano-columnar grains and amorphous phase).\nResults show a dependence of the transverse modes on the nano-structure. The\nnano-columnar film exhibits two transversal modes as expected for the AlN\nw{\\\"u}rtzite while the equiaxed nano-sized and the amorphous films only exhibit\none isotropic transverse mode as expected in amorphous materials. One important\nresult is that the sound propagation velocity in the AlN amorphous phase is\nhigher than the one in the non-textured nano-crystalline phase. This phenomenon\nhas, however, already been observed in ferroelectric ceramics."
    },
    {
        "anchor": "Giant Anomalous Nernst Effect in Noncollinear Antiferromagnetic Mn-based\n  Antiperovskite Nitrides: The anomalous Nernst effect (ANE) - the generation of a transverse electric\nvoltage by a longitudinal heat current in conducting ferromagnets or\nantiferromagnets - is an appealing approach for thermoelectric power generation\nin spin caloritronics. The ANE in antiferromagnets is particularly convenient\nfor the fabrication of highly efficient and densely integrated thermopiles as\nlateral configurations of thermoelectric modules increase the coverage of heat\nsource without suffering from the stray fields that are intrinsic to\nferromagnets. In this work, using first-principles calculations together with a\ngroup theory analysis, we systematically investigate the spin order-dependent\nANE in noncollinear antiferromagnetic Mn-based antiperovskite nitrides\nMn$_{3}X$N ($X$ = Ga, Zn, Ag, and Ni). The ANE in Mn$_{3}X$N is forbidden by\nsymmetry in the R1 phase but amounts to its maximum value in the R3 phase.\nAmong all Mn$_{3}X$N compounds, Mn$_{3}$NiN presents the most significant\nanomalous Nernst conductivity of 1.80 AK$^{-1}$m$^{-1}$ at 200 K, which can be\nfurther enhanced if strain, electric, or magnetic fields are applied. The ANE\nin Mn$_{3}$NiN, being one order of magnitude larger than that in the famous\nMn$_{3}$Sn, is the largest one discovered in antiferromagnets so far. The giant\nANE in Mn$_{3}$NiN originates from the sharp slope of the anomalous Hall\nconductivity at the Fermi energy, which can be understood well from the Mott\nrelation. Our findings provide a novel host material for realizing\nantiferromagnetic spin caloritronics which promises exciting applications in\nenergy conversion and information processing.",
        "positive": "Electrical detection and nucleation of a magnetic skyrmion in a magnetic\n  tunnel junction observed via operando magnetic microscopy: Magnetic skyrmions are topological spin textures which are envisioned as\nnanometre scale information carriers in magnetic memory and logic devices. The\nrecent demonstration of room temperature stabilization of skyrmions and their\ncurrent induced manipulation in industry compatible ultrathin films were first\nsteps towards the realisation of such devices. However, important challenges\nremain regarding the electrical detection and the low-power nucleation of\nskyrmions, which are required for the read and write operations. Here, we\ndemonstrate, using operando magnetic microscopy experiments, the electrical\ndetection of a single magnetic skyrmion in a magnetic tunnel junction (MTJ) and\nits nucleation and annihilation by gate voltage via voltage control of magnetic\nanisotropy. The nucleated skyrmion can be further manipulated by both gate\nvoltage and external magnetic field, leading to tunable intermediate resistance\nstates. Our results unambiguously demonstrate the readout and voltage\ncontrolled write operations in a single MTJ device, which is a major milestone\nfor low power skyrmion based technologies."
    },
    {
        "anchor": "Microstructure-sensitive uncertainty quantification for crystal\n  plasticity finite element constitutive models using stochastic collocation\n  methods: Uncertainty quantification (UQ) plays a major role in verification and\nvalidation of computational engineering models and simulations, and establishes\ntrust in the predictive capability of computational models. In the materials\nscience and engineering context, where the\nprocess-structure-property-performance linkage is well known to be the only\nroad mapping from manufacturing to engineering performance, numerous integrated\ncomputational materials engineering (ICME) models have been developed across a\nwide spectrum of length-scales and time-scales to relieve the burden of\nresource-intensive experiments. Within the structure-property linkage, crystal\nplasticity finite element method (CPFEM) models have been widely used since\nthey are one of a few ICME toolboxes that allow numerical predictions,\nproviding the bridge from microstructure to properties and performances.\nSeveral constitutive models have been proposed to capture the mechanics and\nplasticity behavior of materials. While some UQ studies have been performed,\nthe robustness and uncertainty of these constitutive models have not been\nrigorously established. In this work, we apply a stochastic collocation (SC)\nmethod to quantify the uncertainty of the three most commonly used constitutive\nmodels in CPFEM, namely phenomenological models (with and without twinning),\nand dislocation-density-based constitutive models, for three different types of\ncrystal structures, namely face-centered cubic (fcc) copper (Cu), body-centered\ncubic (bcc) tungsten (W), and hexagonal close packing (hcp) magnesium (Mg). Our\nnumerical results not only quantify the uncertainty of these constitutive\nmodels in stress-strain curves, but also analyze the global sensitivity of the\nunderlying constitutive parameters with respect to the initial yield behavior,\nwhich may be helpful for robust constitutive model calibration works in the\nfuture.",
        "positive": "Microscopic nature of the asymmetric hysteresis in the insulator-metal\n  transition of VO$_2$ revealed by spectroscopic ellipsometry: Systematic spectroscopic ellipsometry investigations have been performed in\norder to elucidate the asymmetric insulator-to-metal transition in thin VO$_2$\nfilms. The comprehensive analysis of the obtained macroscopic optical response\nyields a hysteretic behavior, and in particular its asymmetry, when performed\nin the framework of an anisotropic effective medium approximation taking into\naccount the volume fraction of the metal inclusions as well as their shape. We\nreveal microscopic details of the percolation transition, namely that the shape\nof the metal inclusions goes through several plateaus, as seen in the evolution\nof the shape factor on both sides of the transition region and resulting in\ndifferent critical volume fractions at the transition for the heating and\ncooling cycles."
    },
    {
        "anchor": "Influence of Thermal Cycling on Giant Magnetocaloric Effect of\n  Gd5Si1.3Ge2.7 Thin Film: In the lifetime of a magnetic refrigerator the materials are subjected to\nmillions of thermal magnetic cycles, so it is of the utmost importance to\npredict the behavior of such materials when subjected to related work\nconditions. Thus, in this work we investigated the influence of thermal cycling\nin the microstructure, magnetic phase transition and magnetic entropy change of\na Gd5Si1.3Ge2.7 thin film up to 1000 cycles. In a first stage, till 450 cycles,\nthe hysteresis area of the magnetization curves as a function of temperature\nwas found to decrease 16% with thermal cycling, due to an arresting of the\nO(II) phase caused by internal strain. Nonetheless, after 1000 cycles there is\na clear loss of the magneto-structural transition. For all thermal cycles the\nO(I) phase remains unchanged. Therefore, prolonged thermal cycling leads to a\nstrong reduction of the O(II) phase, attributed to an internal pressure\nbuild-up, caused by the large number of expansion/compression cycles that the\nO(II) phase undergoes across the magnetostructural transition.",
        "positive": "Analytical Model for the Optical Functions of Indium Gallium Nitride\n  with Application to Thin Film Solar Photovoltaic Cells: This paper presents the preliminary results of optical characterization using\nspectroscopic ellipsometry of wurtzite indium gallium nitride (InxGa1-xN) thin\nfilms with medium indium content (0.38<x<0.68) that were deposited on silicon\ndioxide using plasma-enhanced evaporation. A Kramers-Kronig consistent\nparametric analytical model using Gaussian oscillators to describe the\nabsorption spectra has been developed to extract the real and imaginary\ncomponents of the dielectric function ({\\epsilon}1, {\\epsilon}2) of InxGa1-xN\nfilms. Scanning electron microscope (SEM) images are presented to examine film\nmicrostructure and verify film thicknesses determined from ellipsometry\nmodelling. This fitting procedure, model, and parameters can be employed in the\nfuture to extract physical parameters from ellipsometric data from other\nInxGa1-xN films."
    },
    {
        "anchor": "L\u00e9vy-flight intermixing: anomalous nanoscale diffusion in Pt/Ti: Probing the anomalous nanoscale intermixing using molecular dynamics (MD)\nsimulations in Pt/Ti bilayer we reveal the superdiffusive nature of interfacial\natomic transport. It is shown that the Pt atoms undergo anomalous atomic\ntransport across the anisotropic interface of Pt/Ti with suprisingly high rates\nwhich can be characterized as L\\'evy flights. L\\'evy flight is not a unique\nphenomenon in nature, however, no such events have been reported yet for bulk\ninterdiffusion. In particular, the low-energy (0.5 keV) ion-sputtering induced\ntransient enhanced intermixing has been studied by MD simulations. Ab initio\ndensity functional calculations have been used to check and reparametrize the\nemployed heteronuclear interatomic potential. The L\\'evy-intermixing behavior\nexplains the high diffusity tail in the concentration profile obtained by Auger\nelectron spectroscopy depth profiling (AES-DP) analysis in Pt/Ti bilayer\n(reported in ref.: P. S\\\"ule, {\\em et al.}, J. Appl. Phys., {\\bf 101}, 043502\n(2007)).",
        "positive": "Effect of crystalline anisotropy on vertical (-201) and (010) beta-Ga2O3\n  Schottky barrier diodes on EFG single-crystal substrates: Vertical (-201) and (010) beta-Ga2O3 Schottky barrier diodes (SBDs) were\nfabricated on single-crystal substrates grown by edge-defined film-fed growth\n(EFG) method. High resolution X-ray diffraction (HRXRD) and atomic force\nmicroscopy (AFM) confirmed good crystal quality and surface morphology of the\nsubstrates. The electrical properties of both devices, including\ncurrent-voltage (I-V) and capacitance-voltage (C-V) characteristics, were\ncomprehensively measured and compared. The (-201) and (010) SBDs exhibited\non-resistances (Ron) of 0.56 and 0.77 m{\\Omega}cm2, turn-on voltages (Von) of\n1.0 and 1.3 V, Schottky barrier heights (SBH) of 1.05 and 1.20 eV, electron\nmobilities of 125 and 65 cm2/(Vs), respectively, with a high on-current of ~1.3\nkA/cm2 and on/off ratio of ~109. The (010) SBD had a larger Von and SBH than\n(-201) SBD due to anisotropic surface properties (i.e., surface Fermi level\npinning and band bending), as supported by X-ray photoelectron spectroscopy\n(XPS) measurements. Temperature-dependent I-V also revealed the inhomogeneous\nnature of the SBH in both devices, where (-201) SBD showed a more uniform SBH\ndistribution. The homogeneous SBH was also extracted: 1.33 eV for (-201) SBD\nand 1.53 eV for (010) SBD. The reverse leakage current of the devices was well\ndescribed by the two-step trap-assisted tunneling model and the one-dimensional\nvariable range hopping conduction (1D-VRH) model. The (-201) SBD showed larger\nleakage current due to its lower SBH and smaller activation energy. These\nresults indicate the crystalline anisotropy of beta-Ga2O3 can affect the\nelectrical properties of vertical SBDs and should be taken into consideration\nwhen designing beta-Ga2O3 electronics."
    },
    {
        "anchor": "Tunable Half-metallic Magnetism in Atom-thin Holey Two-dimensional\n  C$_2$N Monolayer: Exploring two-dimensional (2D) materials with magnetic ordering is a focus of\ncurrent research. It remains a challenge to achieve tunable magnetism in a\nmaterial of one-atom-thickness without introducing extrinsic magnetic atoms or\ndefects. Here, based on first-principles calculations, we propose that tunable\nferromagnetism can be realized in the recently synthesized holey 2D C$_2$N\n($h$2D-C$_2$N) monolayer via purely electron doping that can be readily\nachieved by gating. We show that owing to the prominent van Hove singularity in\nthe band structure, the material exhibits ferromagnetism even at a small doping\nlevel. Remarkably, over a wide doping range of 4$\\times$10$^{13}$/cm$^2$ to\n8$\\times$10$^{13}$/cm$^2$, the system becomes half-metallic, with carriers\nfully spin-polarized. The estimated Curie temperature can be up to 320 K.\nBesides gating, we find that the magnetism can also be effectively tuned by\nlattice strain. Our result identifies $h$2D-C$_2$N as the first material with\nsingle-atom-thickness that can host gate-tunable room-temperature half-metallic\nmagnetism, suggesting it as a promising platform to explore nanoscale magnetism\nand flexible spintronic devices.",
        "positive": "Potential of monolayer charge: We introduce the potential of monolayer charge (PMC) as a new milepost in\nelectrical double-layer (EDL) studies. We have estimated the PMC values for\ninterfaces of Au(111) and a set of frisbee-shaped polycyclic heteroaromatic\nhydrocarbon ions using density functional theory (DFT) calculations. The\nresults suggest that increasing the ions area allows the formation of ionic\nmonolayers at experimentally achievable potentials. We provide an analytical\nexpression between ion area, surface--ion distance, ionic charge, and the\ncorresponding PMC value to guide the experimental verification. Further\ncomputational and experimental investigations of the PMC as the reference\npotential will contribute to developing fundamental electrochemistry and\nestablishing interfacial electrophysics."
    },
    {
        "anchor": "Microstructural and morphological properties of homoepitaxial (001)ZnTe\n  layers investigated by x-ray diffuse scattering: The microstructural and morphological properties of homoepitaxial (001)ZnTe\nlayers are investigated by x-ray diffuse scattering. High resolution reciprocal\nspace maps recorded close to the ZnTe (004) Bragg peak show different diffuse\nscattering features. One kind of cross-shaped diffuse scattering streaks along\n<111> directions can be attributed to stacking faults within the epilayers.\nAnother kind of cross-shaped streaks inclined at an angle of about 80deg with\nrespect to the <110> in-plane direction arises from the morphology of the\nepilayers. (abridged version)",
        "positive": "Theory of I-V Characteristics of Magnetic Josephson Junctions: We analyze the electrical characteristics of a circuit consisting of a free\nthin-film magnetic layer and source and drain electrodes that have opposite\nmagnetization orientations along the free magnet's two hard directions. We find\nthat when the circuit's current exceeds a critical value there is a sudden\nresistance increase which can be large in relative terms if the currents to\nsource or drain are strongly spin polarized and the free magnet is thin. This\nbehavior can be partly understood in terms of a close analogy between the\nmagnetic circuit and a Josephson junction."
    },
    {
        "anchor": "Diamagnetic magnetocaloric effect due to a transversal oscillating\n  magnetic field: The present Letter describes the magnetocaloric effect of a diamagnetic\nmaterial with a magnetic field $B_\\parallel$ along the $z$ axis and a\ntransversal and oscillating field $B_\\perp (\\ll B_\\parallel)$ parallel to the\n$x-y$ plane. We show that the magnetocaloric potentials due to a change in\n$B_\\parallel$ is the same as those due to a change in the frequency of\n$B_\\perp$. These results raise the possibility of building magnetocaloric\ndevices without moving parts, since changing frequency is a simple electronic\nissue, while changing the field from permanent magnets depends on mechanical\naspects.",
        "positive": "Topological nature of FeSe$_{0.5}$Te$_{0.5}$ superconductor: We demonstrate, using first-principles calculations, that the electronic\nstructure of FeSe$_{1-x}$Te$_{x}$ ($x$=0.5) is topologically non-trivial,\ncharacterized by an odd $\\mathbb Z_2$ invariant and Dirac cone type surface\nstates, in sharp contrast to the end member FeSe ($x$=0). This topological\nstate is induced by the enhanced three-dimensionality and spin-orbit coupling\ndue to Te substitution (compared to FeSe), characterized by a band inversion at\nthe $Z$ point of the Brillouin zone, which is confirmed by our ARPES\nmeasurements. The results suggest that the surface of FeSe$_{0.5}$Te$_{0.5}$\nmay support a non-trivial superconducting channel in proximity to the bulk."
    },
    {
        "anchor": "Charge Carrier Transport in Iron Pyrite Thin Films: Disorder Induced\n  Variable Range Hopping: The origin of p-type conductivity and the mechanism responsible for low\ncarrier mobility was investigated in pyrite (FeS2) thin films. Temperature\ndependent resistivity measurements were performed on polycrystalline and\nnanostructured thin films prepared by three different methods. Films have a\nhigh hole density and low mobility regardless of the method used for their\npreparation. The charge transport mechanism is determined to be nearest\nneighbour hopping (NNH) at near room temperature with Mott-type variable range\nhopping (VRH) of holes via localized states occurring at lower temperatures.\nDensity functional theory (DFT) predicts that sulfur vacancy induced localized\ndefect states will be situated within the band gap with the charge remaining\nlocalized around the defect. The data indicate that the electronic properties\nincluding hopping transport in pyrite thin films can be correlated to sulfur\nvacancy related defect. The results provide insights on electronic properties\nof pyrite thin films and its implications for charge transport",
        "positive": "Quantum Emission From Hexagonal Boron Nitride Monolayers: Atomically thin van der Waals crystals have recently enabled new scientific\nand technological breakthroughs across a variety of disciplines in materials\nscience, nanophotonics and physics. However, non-classical photon emission from\nthese materials has not been achieved to date. Here we report room temperature\nquantum emission from hexagonal boron nitride nanoflakes. The single photon\nemitter exhibits a combination of superb quantum optical properties at room\ntemperature that include the highest brightness reported in the visible part of\nthe spectrum, narrow line width, absolute photo-stability, a short excited\nstate lifetime and a high quantum efficiency. Density functional theory\nmodeling suggests that the emitter is the antisite nitrogen vacancy defect that\nis present in single and multi-layer hexagonal boron nitride. Our results\nconstitute the unprecedented potential of van der Waals crystals for\nnanophotonics, optoelectronics and quantum information processing."
    },
    {
        "anchor": "Computational Study of Electron Paramagnetic Resonance Spectra for Li\n  and Ga Vacancies in LiGaO2: A computational study of the Electron Paramagnetic Resonance (EPR)\n$g$-tensors and hyperfine tensors of Li and Ga vacancies in LiGaO$_2$ is\npresented. Density Functinal Theory (DFT) calculations are carried out of the\nGa and Li vacancies using the DFT+U approach in the charge states which carry\nan unpaired spin. In both vacancies the hole is located on one oxygen\n$p$-orbital adjacent to the vacancy. Apical and different basal plane O are\nconsidered. The magnetic resonance parameters of the defects are determined\nusing the Gauge Including Projector Augmented Wave (GIPAW) method. The EPR\nspectra of $V_\\mathrm{Ga}^{2-}$ is characterized by a quasi-isotropic\nsuperhyperfine (SHF) interaction with one Ga nucleus and for the apical O spin\ngives a $g$-tensor with maximum oriented along the bond direction from that O\nto its other Ga neighbor. For $V_\\mathrm{Li}^0$ there is a quasi-isotropic SHF\ninteraction with two Ga nuclei and the $g$-tensor maximum is along ${\\bf c}$\nfor the basal plane O spin. Both of these are in agreement with experiment but\nwe predict also the $g$-tensors for the other possible localization of the\nspins as well as the small hyperfine splittings (as yet not observed) on Li.\nThe energies of formation and transition levels of the corresponding defects\nprovide insight into the conditions required to activate these EPR spectra.",
        "positive": "Pressure induced emergence of visible luminescence in $Cs_3Bi_2Br_9$:\n  Effect of structural distortion in optical behaviour: We report emergence of photoluminescence at room temperature in trigonal\n$Cs_3Bi_2Br_9$ at high pressures. Enhancement in intensity with pressure is\nfound to be driven by increase in distortion of $BiBr_6$ octahedra and\niso-structural transitions. Electronic band structure calculations show the\nsample in the high pressure phase to be an indirect band gap semiconductor. The\nluminescence peak profile show signatures related to the recombination of free\nand self trapped excitons, respectively. Blue shift of the both peaks till\nabout 4.4 GPa are due to the exciton recombination before relaxation due to the\ndecrease in exciton lifetime with scattering from phonons"
    },
    {
        "anchor": "First-principles theory of low-energy electron diffraction and quantum\n  interference in few-layer graphene: We present a computationally efficient method to incorporate\ndensity-functional theory into the calculation of reflectivity in low-energy\nelectron microscopy. The reflectivity is determined by matching plane waves\nrepresenting the electron beams to the Kohn-Sham wave functions calculated for\na finite slab in a supercell. We show that the observed quantum interference\neffects in the reflectivity spectra of a few layers of graphene on a substrate\ncan be reproduced well by the calculations using a moderate slab thickness.",
        "positive": "Unusually High and Anisotropic Thermal Conductivity in Amorphous Silicon\n  Nanostructures: Amorphous Si (a-Si) nanostructures are ubiquitous in numerous electronic and\noptoelectronic devices. Amorphous materials are considered to possess the lower\nlimit to the thermal conductivity (k), which is ~1 W/m-K for a-Si. However,\nrecent work suggested that k of micro-thick a-Si films can be greater than 3\nW/m-K, which is contributed by propagating vibrational modes, referred to as\n\"propagons\". However, precise determination of k in a-Si has been elusive.\nHere, we used novel structures of a-Si nanotubes and suspended a-Si films that\nenabled precise in-plane k measurement within a wide thickness range of 5 nm to\n1.7 um. We showed unexpectedly high in plane k in a-Si nanostructures, reaching\n~3.0 and 5.3 W/m-K at 100 nm and 1.7 um, respectively. Furthermore, the\nmeasured in plane k is significantly higher than the cross-plane k on the same\nfilms. This usually high and anisotropic k in the amorphous Si nanostructures\nmanifests the surprising broad propaganda mean free path distribution, which is\nfound to range from 10 nm to 10 um, in the disordered and atomically isotropic\nstructure. This result provides an unambiguous answer to the century-old\nproblem regarding the mean free path distribution of propagons and also shed\nlight on the design and performance of numerous a-Si based electronic and\noptoelectronics devices."
    },
    {
        "anchor": "Skin layer of BiFeO3 single crystals: A surface layer (\"skin\") that is functionally and structurally different from\nthe bulk was found in single crystals of BiFeO3. Impedance analysis indicates\nthat a previously reported anomaly at T* ~ 275 \\pm 5 ^/circC corresponds to a\nphase transition confined at the surface of BiFeO3. X-ray photoelectron\nspectroscopy and X-ray diffraction as a function of both incidence angle and\nphoton wavelength unambiguously confirm the existence of a skin with an\nestimated skin depth of few nanometres, elongated out-of-plane lattice\nparameter, and lower electron density. Temperature-dependent x-ray diffraction\nhas revealed that the skin's out of plane lattice parameter changes abruptly at\nT*, while the bulk preserves an unfeatured linear thermal expansion. The\ndistinct properties of the skin are likely to dominate in large surface to\nvolume ratios scenarios such as fine grained ceramics and thin films, and\nshould be particularly relevant for electronic devices that rely on interfacial\ncouplings such as exchange bias.",
        "positive": "Phonon Control of Magnetic Relaxation in the Pyrochlore Slab Compounds\n  SCGO and BSZCGO: We are interested in the phonon response in the frustrated magnets\nSrCr$_{9x}$Ga$_{12-9x}$O$_{19}$ (SCGO) and\nBa$_{2}$Sn$_{2}$ZnCr$_{7x}$Ga$_{10-7x}$O$_{22}$ (BSZCGO). The motivation of the\nstudy is the recently discovered, phonon-driven, magnetic relaxation in the\nSCGO compound [Mutka et al. PRL {\\bf 97} 047203 (2006)] pointing out the\nimportance of a low-energy ($\\hbar\\omega\\sim$7 meV) phonon mode. In neutron\nscattering experiments on these compounds the phonon signal is partly masked by\nthe magnetic signal from the Cr moments and we have therefore examined in\ndetail the non-magnetic isostructural counterparts SrGa$_{12}$O$_{19}$ (SGO)\nand Ba$_{2}$Sn$_{2}$ZnGa$_{10}$O$_{22}$ (BSZGO). Our {\\it ab-initio} lattice\ndynamics calculations on SGO reveal a peak in the vibrational density of states\nmatching with the neutron observations on SGO and SCGO. A strong contribution\nin the vibrational density of states comes from the partial contribution of the\nGa atoms on the 2b and 12k sites, involving modes at the M--point of the\nhexagonal system. These modes comprise dynamics of the kagom\\'e planes of the\npyrochlore slab magnetic sub-lattice, 12k sites, and therefore can drive\nmagnetic relaxation via spin-phonon coupling. Both BSZCGO and BSZGO show a\nsimilar low-energy Raman peak but no corresponding peak in the neutron\ndetermined density of states of BSZGO is seen. However, a strong non-Debye\nenhancement of low-energy phonon response is observed. We attribute this\nparticular feature to the Zn/Ga disorder on the 2$d$ -site, already evoked\nearlier to affect the magnetic properties of BSZCGO. We propose that this\ndisorder-induced phonon response explains the absence of a characteristic\nenergy scale and the much faster magnetic relaxation observed in BSZCGO."
    },
    {
        "anchor": "Sr1.5Ba0.5Zn2Fe12O22 Hexaferrites Ferromagnetic Resonance and Nonlinear\n  Excitation for Magneto-Electric Devices: A magneto electric (ME) effect was reported [1] for the insulator material of\nhelimagnetic hexaferrite of Sr1.5Ba0.5Zn2Fe12O22. In this study we are\ninterested in investigating this materials ferromagnetic resonance to define\nits internal anisotropy fields. By using a vibrating sample magnetometer (VSM)\nand ferromagnetic resonance (FMR) analysis we realized that this helical\nhexaferrite has about -0.5 kOe exchange anisotropy field of HE. Also, by using\nan alternative free energy model we derived this materials Polder tensor and\nits ferromagnetic resonance condition. Meanwhile, we were able to show a\npotential magneto electric coupling by nonlinear excitation of planar helical\nhexaferrite, in which a magnetic nonlinear excitation is integrated into\ndielectric permittivity.\n  Index Terms, Ferrites, ferromagnetic resonances, and magnetic nonlinear\nexcitations.",
        "positive": "Quasicrystal structure prediction: A review: Predicting quasicrystal structures is a multifaceted problem that can involve\npredicting a previously unknown phase, predicting the structure of an\nexperimentally observed phase, or predicting the thermodynamic stability of a\ngiven structure. We survey the history and current state of these prediction\nefforts with a focus on methods that have improved our understanding of the\nstructure and stability of known metallic quasicrystal phases. Advances in the\nstructural modeling of quasicrystals, along with first principles total energy\ncalculation and statistical mechanical methods that enable the calculation of\nquasicrystal thermodynamic stability, are illustrated by means of cited\nexamples of recent work."
    },
    {
        "anchor": "DFT Perspective of Hydrogen Storage on Porous Materials: In this chapter, the physisorption of hydrogen molecules in porous materials\nas possible hydrogen storage systems has been reviewed. Owing to the weak\ninteraction between H2 molecules and the adsorbent, high storage capacities are\ntypically reached only at cryogenic temperature. Different classes of porous\nmaterials possessing different structure and composition have been designed for\nhydrogen storage applications using computational methods and especially with\nthe aid of DFT methods. The adsorption energies for hydrogen in different\nporous materials have been increases by the doping of light weight alkali and\nalkali earth metals. Ab initio molecular dynamics has been carried out to know\nthe stability of the newly functionalized materials. GCMC methods have been\nemployed to know the gravimetric and volumetric uptake percentage of the newly\nfunctionalized materials. Therefore, the combined approach provides a better\nunderstanding and designing new materials to operate at near room temperature\nfor the reversible hydrogen storage application.",
        "positive": "Separation and Electrical Properties of Self-Organized Graphene/Graphite\n  Layers: Intrinsic layered structure of graphite is the source of ongoing and\nexpanding search of ways of obtaining low-cost and promising graphite thin\nlayers. We report on a novel method of obtaining and separating rubbed graphite\nsheets by using water soluble NaCl substrate. The electrical behavior of sheets\nwas characterized by current-voltage measurements. An in-plane electrical\nunisotropy depending on rubbing direction is discovered. Optical microscopy\nobservations combined with discovered non-linear electrical behavior revealed\nthat friction leads to the formation of sheet makeup which contain an optically\ntransparent lamina of self-organized few-layer graphene."
    },
    {
        "anchor": "Spinodal Decomposition-Enabled Halide Perovskite Double Heterostructure\n  with Reduced Fr\u00f6hlich Electron-Phonon Coupling: Epitaxial III-V semiconductor heterostructures are key components in modern\nmicroelectronics, electro-optics and optoelectronics. With superior\nsemiconducting properties, halide perovskite materials are rising as promising\ncandidates for coherent heterostructure devices. In this report, spinodal\ndecomposition is proposed and experimentally implemented to produce epitaxial\ndouble heterostructures in halide perovskite system. Pristine epitaxial mixed\nhalide perovskites rods and films were synthesized via Van der Waals epitaxy by\nchemical vapor deposition method. At room temperature, photon was applied as a\nknob to regulate the kinetics of spinodal decomposition and classic coarsening.\nBy this approach, halide perovskite double heterostructures were created\ncarrying epitaxial interfaces and outstanding optical properties. Reduced\nFr\\\"ohlich electron-phonon coupling was discovered in coherent halide double\nheterostructure, which is hypothetically attributed to the classic phonon\nconfinement effect widely existing in III-V double heterostructures. The\nability to develop coherent double heterostructures in halide perovskites paves\nan avenue to exploring halide perovskite-based quantum wells and superlattices\nfor high-performance and low-cost optoelectronics, electro-optics and\nmicroelectronics.",
        "positive": "Thermal and electrical characterization of\n  poly(vinyl)alcohol)/poly(vinylidene fluoride) blends reinforced with\n  nano-grapheneplatelets: Nano-graphene /polymer composites can functionas pressure induced\nelectro-switches, at concentrations around their conductivity percolation\nthreshold. Close to the critical point, the pressure dependence of the electron\ntunneling through the polymer barrier separating nanon-graphenes results from\nthecompetition among shorteningof the tunneling length and the increase of the\npolymer's polarizability. Such switching behaviorwas recentlyobserved\ninpolyvinyl alcohol (PVA) loaded withnano-graphene platelets (NGPs). In this\nwork, PVA is blended withh alpha-poly(vinylidene fluoride) (PVdF)and NGPs.\nCoaxial mechanical stress and electric field render the nano-composite\npiezoelectric. We investigate the influence of heterogeneity, thermal\nproperties, phase transitions and kinetic processes occurring in the polymer\nmatrix on the macroscopicelectrical conductivity and interfacial polarization\nin casted specimens. Furthermore, the effect of electro-activity of PVdF grains\non the electric and thermal properties are comparatively studied. Broadband\nDielectricspectroscopy is employed to resolve and inspect electron transport\nand trapping with respect to thermal transitions and kineticprocessestraced via\nDifferential Scanning Calorimetry. The harmonic electric field applied during a\nBDS sweep induces volume modifications of the electro-active PVdF grains,\nwhile, electro-activity of PVdF grains can disturb the internal electric field\nthat free (or bound) electric. The dc conductivity and dielectric relaxation\nwas found to exhibit weakdependencies."
    },
    {
        "anchor": "Quasiparticle electronic structure of phthalocyanine:TMD interfaces from\n  first-principles $GW$: Interfaces formed between monolayer transition metal dichalcogenides (TMDs)\nand (metallo)phthalocyanine molecules are promising in energy applications and\nprovide a platform for studying mixed-dimensional molecule-semiconductor\nheterostructures in general. An accurate characterization of the frontier\nenergy level alignment at these interfaces is key in the fundamental\nunderstanding of the charge transfer dynamics between the two photon absorbers.\nHere, we employ the first-principles substrate screening $GW$ approach to\nquantitatively characterize the quasiparticle electronic structure of a series\nof interfaces: metal-free phthalocyanine (H$_2$Pc) adsorbed on monolayer MX$_2$\n(M=Mo, W; X=S, Se) and zinc phthalocyanine (ZnPc) adsorbed on MoX$_2$ (X=S,\nSe). Furthermore, we reveal the dielectric screening effect of the commonly\nused $\\alpha$-quartz (SiO$_2$) substrate on the H$_2$Pc:MoS$_2$ interface,\nusing the dielectric embedding $GW$ approach. Our calculations furnish the\nfirst set of $GW$ results for these interfaces, providing structure-property\nrelationship across a series of similar systems and benchmarks for future\nexperimental and theoretical studies.",
        "positive": "Screened-exchange density functional theory description of the\n  electronic structure and phase stability of the chalcopyrite materials\n  AgInSe$_2$ and AuInSe$_2$: We present a systematic assessment of the structural properties, the\nelectronic density of states, the charge densities, and the phase stabilities\nof AgInSe$_2$ and AuInSe$_2$ using screened exchange hybrid density functional\ntheory, and compare their properties to those of CuInSe$_2$. For AgInSe$_2$,\nhybrid density functional theory properly captures several experimentally\nmeasured properties, including the increase in the band gap and the change in\nthe direction of the lattice distortion parameter $u$ in comparison to\nCuInSe$_2$. While the electronic properties of AuInSe$_2$ have not yet been\nexperimentally characterized, we predict it to be a small gap ($\\approx 0.15$\neV) semiconductor. We also present the phase stability of AgInSe$_2$ and\nAuInSe$_2$ according to screened-exchange density functional theory, and\ncompare the results to predictions from conventional density functional theory,\nresults tabulated from several online materials data repositories, and\nexperiment (when available). In comparison to conventional density functional\ntheory, the hybrid functional predicts phase stabilities of AgInSe$_2$ in\nbetter agreement with experiment: discrepancies in the calculated formation\nenthalpies are reduced by approximately a factor of three, from $\\approx$ 0.20\neV/atom to $\\approx$ 0.07 eV/atom, similar to the improvement observed for\nCuInSe$_2$. We further predict that AuInSe$_2$ is not a stable phase, and can\nonly be present under non-equilibrium conditions."
    },
    {
        "anchor": "Localized excited charge carriers generate ultrafast inhomogeneous\n  strain in the multiferroic BiFeO$_3$: We apply ultrafast X-ray diffraction with femtosecond temporal resolution to\nmonitor the lattice dynamics in a thin film of multiferroic BiFeO$_3$ after\nabove-bandgap photoexcitation. The sound-velocity limited evolution of the\nobserved lattice strains indicates a quasi-instantaneous photoinduced stress\nwhich decays on a nanosecond time scale. This stress exhibits an inhomogeneous\nspatial profile evidenced by the broadening of the Bragg peak. These new data\nrequire substantial modification of existing models of photogenerated stresses\nin BiFeO$_3$: the relevant excited charge carriers must remain localized to be\nconsistent with the data.",
        "positive": "Ideal regularization of the Coulomb singularity in exact exchange by\n  Wigner-Seitz truncated interactions: towards chemical accuracy in non-trivial\n  systems: Hybrid density functionals show great promise for chemically-accurate first\nprinciples calculations, but their high computational cost limits their\napplication in non-trivial studies, such as exploration of reaction pathways of\nadsorbents on periodic surfaces. One factor responsible for their increased\ncost is the dense Brillouin-zone sampling necessary to accurately resolve an\nintegrable singularity in the exact exchange energy. We analyze this\nsingularity within an intuitive formalism based on Wannier-function\nlocalization and analytically prove Wigner-Seitz truncation to be the ideal\nmethod for regularizing the Coulomb potential in the exchange kernel. We show\nthat this method is limited only by Brillouin-zone discretization errors in the\nKohn-Sham orbitals, and hence converges the exchange energy exponentially with\nthe number of k-points used to sample the Brillouin zone for all but\nzero-temperature metallic systems. To facilitate the implementation of this\nmethod, we develop a general construction for the plane-wave Coulomb kernel\ntruncated on the Wigner-Seitz cell in one, two or three lattice directions. We\ncompare several regularization methods for the exchange kernel in a variety of\nreal systems including low-symmetry crystals and low-dimensional materials. We\nfind that our Wigner-Seitz truncation systematically yields the best k-point\nconvergence for the exchange energy of all these systems and delivers an\naccuracy to hybrid functionals comparable to semi-local and screened-exchange\nfunctionals at identical k-point sets."
    },
    {
        "anchor": "High throughput thermal conductivity of high temperature solid phases:\n  The case of oxide and fluoride perovskites: Using finite-temperature phonon calculations and machine-learning methods, we\ncalculate the mechanical stability of about 400 semiconducting oxides and\nfluorides with cubic perovskite structures at 0 K, 300 K and 1000 K. We find 92\nmechanically stable compounds at high temperatures -- including 36 not\nmentioned in the literature so far -- for which we calculate the thermal\nconductivity. We demonstrate that the thermal conductivity is generally smaller\nin fluorides than in oxides, largely due to a lower ionic charge, and describe\nsimple structural descriptors that are correlated with its magnitude.\nFurthermore, we show that the thermal conductivities of most cubic perovskites\ndecrease more slowly than the usual $T^{-1}$ behavior. Within this set, we also\nscreen for materials exhibiting negative thermal expansion. Finally, we\ndescribe a strategy to accelerate the discovery of mechanically stable\ncompounds at high temperatures.",
        "positive": "Secondary electron emission and yield spectra of metals from Monte Carlo\n  simulations and experiments: In this work, we present a computational method, based on the Monte Carlo\nstatistical approach, for calculating electron energy emission and yield\nspectra of metals, such as copper, silver and gold. The calculation of these\nobservables proceeds via the Mott theory to deal with the elastic scattering\nprocesses, and by using the Ritchie dielectric approach to model the electron\ninelastic scattering events. In the latter case, the dielectric function, which\nrepresents the starting point for the evaluation of the energy loss, is\nobtained from experimental reflection electron energy loss spectra. The\ngeneration of secondary electrons upon ionization of the samples is also\nimplemented in the calculation. A remarkable agreement is obtained between both\ntheoretical and experimental electron emission spectra and yield curves."
    },
    {
        "anchor": "Synthesis and Thin Films of Thermally Robust Quartet (S = 3/2) Ground\n  State Triradical: High spin (S=3/2) organic triradicals may offer enhanced properties with\nrespect to several emerging technologies, but those synthesized to date\ntypically exhibit small doublet quartet energy gaps and/or possess limited\nthermal stability and processability. We report a quartet ground state\ntriradical 3, synthesized by a Pd(0)-catalyzed radical-radical cross-coupling\nreaction, which possesses two doublet-quartet energy gaps, DeltaEDQ ~ 0.2-0.3\nkcal mol-1 and DealtaEDQ2 ~ 1.2-1.8 kcal mol-1. The triradical has a 70+%\npopulation of the quartet ground state at room temperature, and good thermal\nstability with onset of decomposition at > 160 {\\deg}C under inert atmosphere.\nMagnetic properties of 3 are characterized by SQUID magnetometry in polystyrene\nglass and by quantitative EPR spectroscopy. Triradical 3 is evaporated under\nultra-high vacuum to form thin films of intact triradicals on silicon\nsubstrate, as confirmed by high resolution X-ray photoelectron spectroscopy.\nAFM and SEM images of the around 1 nm thick films indicate that the triradical\nmolecules form islands on the substrate. The films are stable under ultra-high\nvacuum for at least 17 h but show onset of decomposition after 4 h at ambient\nconditions. The drop-cast films are less prone to degradation in air and have\nlonger lifetime.",
        "positive": "Gold Nanoparticle Superlattice in Porous Silica and Low Temperature\n  Catalytic CO Oxidation: The practical use of nanoparticle superlattices (NPSLs) which are of great\ninterest as materials with designed functionalities is often limited by their\nlack of structural stability under various utilization conditions. Here, we\nreport a new method for directly synthesizing NPSL fully embedded in\nhierarchically porous silica which provides exceptional stability and efficient\npathways for reactant molecules, making the NPSL highly efficient catalyst. The\nsuperlattices made of 12 nm gold nanoparticles exhibit exceptionally high\ncatalytic activity for CO oxidation at low temperature, showing higher activity\nthan that of small gold nanoparticles (ca. 3 nm) supported on metal oxides. The\ngold NPSL also shows unprecedented stability, maintaining its structural\nstability and catalytic activity without any signature of degradation over a\nmonth of continuous catalytic reaction, which present one significant step\nforward to realizing the great potentials of gold catalysts in automotive\nemission control and green chemistry industry."
    },
    {
        "anchor": "Manipulating waves with LEGO$^{\\circledR}$ bricks: A versatile\n  experimental platform for metamaterial architectures: In this letter, we discuss a versatile, fully-reconfigurable experimental\nplatform for the investigation of phononic phenomena in metamaterial\narchitectures. The approach revolves around the use of 3D laser vibrometry to\nreconstruct global and local wavefield features in specimens obtained through\nsimple arrangements of LEGO$^{\\circledR}$ bricks on a thin baseplate. The\nagility by which it is possible to reconfigure the brick patterns into a nearly\nendless spectrum of topologies makes this an effective approach for rapid\nexperimental proof of concept, as well as a powerful didactic tool, in the\narena of phononic crystals and metamaterials engineering. We use our platform\nto provide a compelling visual illustration of important spatial wave\nmanipulation effects (waveguiding and seismic isolation), and to elucidate\nfundamental dichotomies between Bragg-based and locally resonant bandgap\nmechanisms.",
        "positive": "Pressure effects on the Raman spectrum of $CaZnF_4$: The pressure influence on the lattice vibration of $CaZnF_4$ has been studied\nby Raman diffusion up to 17 GPa. Most Raman frequencies increase with\nincreasing pressure. Three singularities in the pressure induced frequency\nevolution are observed around 1.5 GPa, 10 GPa and 17 GPa. The samples\npressurized to 17 GPa or higher do not revert to the ambient pressure phase\nafter being released, the new phase showing different Raman spectra from the\nordinary one. It is suggested that $CaZnF_4$ undergoes probably sudden lattice\ndeformations at about 1.5 GPa and 10 GPa, and an irreversible phase\ntransformation above 17 GPa."
    },
    {
        "anchor": "Evolutionary approach for finding the atomic structure of steps on\n  stable crystal surfaces: The problem addressed here can be concisely formulated as follows: given a\nstable surface orientation with a known reconstruction and given a direction in\nthe plane of this surface, find the atomic structure of the steps oriented\nalong that direction. We report a robust and generally applicable\nvariable-number genetic algorithm for step structure determination and\nexemplify it by determining the structure of monatomic steps on\nSi(114)-$2\\times 1$. We show how the location of the step edge with respect to\nthe terrace reconstructions, the step width (number of atoms), and the\npositions of the atoms in the step region can all be simultaneously determined.",
        "positive": "Photonic crystal optical waveguides for on-chip Bose-Einstein\n  condensates: We propose an on-chip optical waveguide for Bose-Einstein condensates based\non the evanescent light fields created by surface states of a photonic crystal.\nIt is shown that the modal properties of these surface states can be tailored\nto confine the condensate at distances from the chip surface significantly\nlonger that those that can be reached by using conventional index-contrast\nguidance. We numerically demonstrate that by index-guiding the surface states\nthrough two parallel waveguides, the atomic cloud can be confined in a\ntwo-dimensional trap at about 1$\\mu$m above the structure using a power of\n0.1mW."
    },
    {
        "anchor": "On parent structures of near-ambient nitrogen-doped lutetium hydride\n  superconductor: Recently, near-ambient superconductivity has been experimentally evidenced in\na nitrogen-doped lutetium hydride by Dasenbrock-Gammon \\emph{et al.} [Nature\n615, 244 (2023)], which yields a remarkable maximum $T_c$ of 294 K at just 10\nkbar. However, due to the difficulty of x-ray diffraction (XRD) in identifying\nlight elements such as hydrogen and nitrogen, the crystal structure of the\nsuperconductor remains elusive, in particular for the actual stoichiometry of\nhydrogen and nitrogen and their atomistic positions. This holds even for its\nparent structure. Here, we set out to address this issue by performing a\nthorough density functional theory study on the structural, electronic,\ndynamical, and optical properties of lutetium hydrides. Through thermal and\nlattice dynamic analysis as well as XRD and superconductor color comparisons,\nwe unambiguously clarified that the parent structures are a mixture of dominant\nLuH$_2$ phase of the CaF$_2$-type (instead of originally proposed LuH$_3$\nstructure of $Fm\\bar{3}m$ space group) and minor LuH phase of the NaCl-type.",
        "positive": "A novel symmetry in nanocarbons: pre-constant discrete principal\n  curvature structure: Since the first-principles calculations in quantum chemistry precisely\nprovide possible configurations of carbon atoms in nanocarbons, we have\nanalyzed the geometrical structure of the possible carbon configurations and\nfound that there exists a novel symmetry in the nanocarbons, i.e., the\npre-constant discrete principal curvature (pCDPC) structure. In terms of the\ndiscrete principal curvature based on the discrete geometry for trivalent\noriented graphs developed by Kotani, Naito, and Omori (Comput. Aided Geom.\nDesign, $\\bf{58}$, (2017), 24-54), we numerically investigated discrete\nprincipal curvature distribution of the nanocarbons, C$_{60}$, carbon\nnanotubes, C$_{120}$ (C$_{60}$ dimer), and C$_{60}$-polymers (peanut-shaped\nfullerene polymers). While the C$_{60}$ and nanotubes have the constant\ndiscrete principal curvature (CDPC) as we expected, it is interesting to note\nthat the C$_{60}$-polymers and C$_{60}$ dimer also have the almost constant\ndiscrete principal curvature, i.e., pCDPC, which is surprising. A nontrivial\npCDPC structure with revolutionary symmetry is available due to discreteness,\nthough it has been overlooked in geometry. In discrete geometry, there appears\na center axisoid which is the discrete analogue of the center axis in the\ncontinuum differential geometry but has three-dimensional structure rather than\na one-dimensional curve due to its discrete nature. We demonstrated that such\npCDPC structure exists in nature, namely in the C$_{60}$-polymers. Furthermore,\nsince we found that there is a positive correlation between the degree of the\nCDPC structure and stability of the configurations for certain class of the\nC$_{60}$-polymers, we also revealed the origin of the pCDPC structure from an\naspect of materials science."
    },
    {
        "anchor": "Band splitting with vanishing spin polarizations in noncentrosymmetric\n  crystals: The Dresselhaus and Rashba effects are well-known phenomena in solid-state\nphysics, in which spin-orbit coupling (SOC) splits spin-up and spin-down energy\nbands of nonmagnetic non-centrosymmetric crystals. Here, we discover a new\nphenomenon, dubbed as band splitting with vanishing spin polarizations (BSVSP),\nin which, as usual, SOC splits the energy bands in nonmagnetic\nnon-centrosymmetric systems; surprisingly, however, both split bands show no\nnet spin polarization along certain high-symmetry lines in the Brillouin zone.\nIn order to rationalize this phenomenon, we propose a new classification of\npoint groups into pseudo-polar and non-pseudo-polar groups. By means of\nfirst-principles simulations, we demonstrate that BSVSP can take place in both\nsymmorphic (e.g., bulk GaAs) and non-symmorphic systems (e.g., two dimensional\nferroelectric SnTe). Furthermore, we propose a novel linear magnetoelectric\ncoupling in reciprocal space, which could be employed to tune the spin\npolarization with an external electric field. The BSVSP effect and its\nmanipulation could therefore pave a new way to novel spintronic devices.",
        "positive": "Atoms to topological electronic materials: A bedtime story for beginners: In this review, We discussed the theoretical foundation and experimental\ndiscovery of different topological electronic states of material in condensed\nmatter. At first, we briefly reviewed the conventional electronic states, which\nhave been realized in band theory of solid. Next, the simplest non-trivial\ninsulating phase (Integer Quantum Hall State) and the concept of topological\norder in condensed matter electronic system have been introduced. In the\nfollowing sections, we discussed Quantum Spin Hall (QSH) State in two\ndimensions (2D), and reviewed the theoretical and experimental developments\nfrom 2D QSH state to 3D topological insulators (TI). Subsequently, we gave a\nbrief overview on theoretical and experimental understanding on recently\ndiscovered topological Dirac semimetals, Weyl semimetals, three-, six- , and\neight-fold degenerate semimetals, and Nodal line semimetals. Then, topological\ncrystalline insulator, which can not be considered as a descendent of Quantum\nSpin Hall or Integer Quantum Hall insulator, has been introduced. Finally, we\ndiscussed the presence of magnetism in some topological materials and its\nconsequence on electronic band structure."
    },
    {
        "anchor": "Chemical assembly of atomically thin transistors and circuits in a large\n  scale: Next-generation electronics calls for new materials beyond silicon for\nincreased functionality, performance, and scaling in integrated circuits.\nCarbon nanotubes and semiconductor nanowires are at the forefront of these\nmaterials, but have challenges due to the complex fabrication techniques\nrequired for large-scale applications. Two-dimensional (2D) gapless graphene\nand semiconducting transition metal dichalcogenides (TMDCs) have emerged as\npromising electronic materials due to their atomic thickness, chemical\nstability and scalability. Difficulties in the assembly of 2D electronic\nstructures arise in the precise spatial control over the metallic and\nsemiconducting atomic thin films. Ultimately, this impedes the maturity of\nintegrating atomic elements in modern electronics. Here, we report the\nlarge-scale spatially controlled synthesis of the single-layer semiconductor\nmolybdenum disulfide (MoS2) laterally in contact with conductive graphene.\nTransition electron microscope (TEM) studies reveal that the single-layer MoS2\nnucleates at the edge of the graphene, creating a lateral 2D heterostructure.\nWe demonstrate such chemically assembled 2D atomic transistors exhibit high\ntransconductance (10 uS), on-off ratios (10^6), and mobility (20 cm^2 V^-1\ns^-1). We assemble 2D logic circuits, such as a heterostructure NMOS inverter\nwith a high voltage gain, up to 70, enabled by the precise site selectivity\nfrom atomically thin conducting and semiconducting crystals. This scalable\nchemical assembly of 2D heterostructures may usher in a new era in\ntwo-dimensional electronic circuitry and computing.",
        "positive": "Stability of different phases of (C60)2 Structures: We investigate the possible binding configurations of pairs of C60 molecules\nwhen pushed against each other. Tersoff potential, which represents\nintramolecular interactions well, has been used to calculate potential\nenergies. We begin relaxation of atomic coordinates at various distances of\nseparation and for all possible mutual orientations of the two molecules. As a\nresult, we have been able to show that several minimum energy configurations\nexist. Some of these configurations have not been reported earlier. Only two\ntypes of dimer structures, involving interlinkage through a single bond, or\nthrough so called 2+2 cycloaddition, have been commonly referred in the\nliterature. Our calculation shows that apart from these configurations, many\ninteresting composite phases also result, such as fused and peanut structures\nand (5,5) and (10,0) nanotubes. A link with experiment to find these structures\ncan be established by application of suitable critical applied pressure in the\nsolid phase, accompanied by high temperature corresponding to orientational\nmelting so that suitable mutual orientations are available. High energy\nmolecular beams of C60 incident upon C60 layers could also achieve the same."
    },
    {
        "anchor": "Observation of Bulk Plasticity in a Polycrystalline Titanium Alloy by\n  Diffraction Contrast Tomography and Topotomography: The mechanical properties of polycrystalline metals are governed by the\ninteraction of defects that are generated by deformation within the 3D\nmicrostructure. In materials that deform by slip, the plasticity is usually\nhighly heterogeneous within the microstructure. Many experimental tools can be\nused to observe the results of slip events at the free surface of a sample;\nhowever, there are only a few methods for imaging these events in the bulk. In\nthis article, the imaging of bulk slip events within the 3D microstructure are\nenabled by the combined use of X-ray diffraction contrast tomography and\ntopotomography. Correlative measurements between high-resolution digital image\ncorrelation, X-ray diffraction contrast tomography, topotomography and phase\ncontrast tomography are performed during deformation of Ti-7Al to investigate\nthe sensitivity of the X-ray topotomography method for the observation of slip\nevents in the bulk. Much larger neighborhoods of grains were able to be mapped\nthan in previous studies, enabling quantitative measurements of slip\ntransmission. Significant differences were observed between surface and bulk\ngrains, indicating the need for 3D observations of plasticity to better\nunderstand deformation in polycrystalline materials.",
        "positive": "A spin wave diode: A diode, a device allowing unidirectional signal transmission, is a\nfundamental element of logic structures and lies in the heart of modern\ninformation systems. Spin wave or magnon, representing a collective\nquasi-particle excitation of the magnetic order in magnetic materials, is a\npromising candidate of information carrier for the next generation\nenergy-saving technologies. Here we propose a scalable and reprogrammable pure\nspin wave logic hardware architecture using domain walls and surface anisotropy\nstripes as waveguides on a single magnetic wafer. We demonstrate theoretically\nthe design principle of the simplest logic component, a spin wave diode,\nutilizing the chiral bound states in a magnetic domain wall with\nDzyaloshiskii-Moriya interaction, and confirm its performance through\nmicromagnetic simulations. Our findings open a new vista for realizing\ndifferent types of pure spin wave logic components and finally achieving an\nenergy-efficient and hardware-reprogrammable spin wave computer."
    },
    {
        "anchor": "Static magnetic proximity effect in Pt/Ni$_{1-x}$Fe$_x$ bilayers\n  investigated by x-ray resonant magnetic reflectivity: We present x-ray resonant magnetic reflectivity (XRMR) as a very sensitive\ntool to detect proximity induced interface spin polarization in Pt/Fe,\nPt/Ni$_{33}$Fe$_{67}$, Pt/Ni$_{81}$Fe$_{19}$ (permalloy), and Pt/Ni bilayers.\nWe demonstrate that a detailed analysis of the reflected x-ray intensity gives\ninsight in the spatial distribution of the spin polarization of a non-magnetic\nmetal across the interface to a ferromagnetic layer. The evaluation of the\nexperimental results with simulations based on optical data from ab initio\ncalculations provides the induced magnetic moment per Pt atom in the spin\npolarized volume adjacent to the ferromagnet. We find the largest spin\npolarization in Pt/Fe and a much smaller magnetic proximity effect in Pt/Ni.\nAdditional XRMR experiments with varying photon energy are in good agreement\nwith the theoretical predictions for the energy dependence of the magnetooptic\nparameters and allow identifying the optical dispersion $\\delta$ and absorption\n$\\beta$ across the Pt L3-absorption edge.",
        "positive": "Ripple formation on Nickel irradiated with radially polarized\n  femtosecond beams: We report on the morphological effects induced by the inhomogeneous\nabsorption of radially polarized femtosecond laser irradiation of nickel (Ni)\nin sub-ablation conditions. A theoretical prediction of the morphology profile\nis performed and the role of surface plasmon excitation in the production of\nself-formed periodic ripples structures is evaluated. Results indicate a\nsmaller periodicity of the ripples profile compared to that attained under\nlinearly polarized irradiation conditions. A combined hydrodynamical and\nthermoelastic model is presented in laser beam conditions that lead to material\nmelting. The simulation results are presented to be in good agreement with the\nexperimental findings. The ability to control the size of the morphological\nchanges via modulating the beam polarization may provide an additional route\nfor controlling and optimizing the outcome of laser micro-processing"
    },
    {
        "anchor": "Size-dependent concentration of N0 paramagnetic centres in HPHT\n  nanodiamonds: Size-calibrated commercial nanodiamonds synthesized by high-pressure\nhigh-temperature (HPHT) technique were studied by high-frequency W and\nconventional X band electron paramagnetic resonance (EPR) spectroscopy. The\nnumbers of spins in the studied samples were estimated. The core-shell model of\nthe HPHT nanodiamonds was proposed to explain the observed dependence of the\nconcentration of the N0 paramagnetic centers. Two other observed paramagnetic\ncenters are attributed to the two types of structures in the nanodiamond shell.",
        "positive": "Relation between chemical force and tunneling current in point contacts:\n  a simple model: Aim of this paper is to find out a simple model, which provides more insight\ninto the relation between the tunneling current and the chemical force arising\nduring formation of atomic contact in between a SPM probe and surface atom."
    },
    {
        "anchor": "Formation of complex films with water-soluble CTAB molecules: This communication reports the formation of complex Langmuir monolayer at the\nair-water interface with the water-soluble -trimethyl ammonium bromide (CTAB)\nmolecules when interacted with the stearic acid (SA) molecules. The reaction\nkinetics of the formation of the CTAB-SA complex was monitored by observing the\nsurface pressure versus time graph. Multilayered LB films of this complex doped\nwith congo red was successfully formed onto a quartz substrate. UV-Vis\nabsorption and steady state fluorescence spectroscopic characteristics of this\ndoped LB films confirms the successful incorporation of congo red molecules in\nto the CTAB-SA complex films.",
        "positive": "Note: Derivative divide, a method for the analysis of broadband\n  ferromagnetic resonance in the frequency domain: Broadband ferromagnetic resonance (bbFMR) spectroscopy is an established\nexperimental tool to quantify magnetic properties. Due to frequency-dependent\ntransmission of the microwave setup, bbFMR measurements in the frequency domain\nrequire a suitable background removal method. Here, we present a measurement\nand data analysis protocol that allows to perform quantitative frequency-swept\nbbFMR measurements without the need for a calibration of the microwave setup.\nThe method, its limitations and advantages are described in detail. Finally the\nmethod is applied to evaluate FMR spectra of a permalloy thin film. The\nextracted material parameters are in very good agreement with those obtained\nusing a conventional analysis in field-space."
    },
    {
        "anchor": "Phonon thermal conductivity by non-local non-equilibrium molecular\n  dynamics: Non-equilibrium (NE) molecular dynamics (MD), or NEMD, gives a \"direct\"\nsimulation of thermal conductivity kappa. Heat H(x) is added and subtracted in\nequal amounts at different places x. After steady state is achieved, the\ntemperature T(x) is found by averaging over finite sections. Usually the aim is\nto extract a value of dT/dx from a place distant from sources and sinks of\nheat. This yields an effective kappa(L) for the thermal conductivity, L being\nthe system size. The result is then studied as a function of L, to extract the\nbulk limit kappa. Here instead, our heat is H(x)~sin(qx), where q=2pi/L. This\ncauses a steady-state temperature T_0 + Delta T sin(2pi x/L). A thermal\nconductivity kappa(q) is extracted, which is well converged at the chosen q (or\nL). Bulk conductivity kappa requires taking the q to 0 limit. The method is\ntested for liquid and crystalline argon. One advantage is reduced computational\nnoise at a given total MD run time. Another advantage is that kappa(q) has a\nmore physical meaning than kappa(L). It can be easily studied using\nPeierls-Boltzmann transport theory. New formulas for kappa(q) in simplified\nDebye-type models give new insight about extrapolation to q to 0 or 1/L to 0.\nIn particular, it is shown that kappa(L$ is unlikely to behave as kappa -C/L,\nand much more likely to behave as kappa-C'/sqrt(L). Convergence problems\nencountered in computational cells with very large aspect ratios\nL(parallel)/L(perp) are also analyzed. Some details are contained in the\n\"Supplemental Material\" file.",
        "positive": "Strain-mediated magnetoelectric coupling in\n  magnetostrictive/piezoelectric heterostructures and resulting high frequency\n  effects: Magnetoelectric coupling terms are derived in piezoelectric/magnetostrictive\n(multiferroic) thin film heterostructures using Landau-Ginzburg free energy\nexpansions in terms of strain and by considering strain boundary conditions\nbetween the two materials. Then, a general effective medium method for solving\nfor the complete electromagnetic susceptibility tensor of such heterostructures\nis used to calculate the ferromagnetic resonance frequency in a\nBaTiO$_3$/NiFe$_2$O$_4$ superlattice. This method differs from existing methods\nfor treating magnetoelectric heterostructures since the magnetic and electric\ndipolar fields are not assumed constant but vary from one film to another. The\nferromagnetic resonance frequency shift is calculated as a function of applied\nelectric field and is compared to some experimental results."
    },
    {
        "anchor": "Phonon Optimized Potentials: Molecular dynamics (MD) simulations have been extensively used to study\nphonons and gain insight, but direct comparisons to experimental data are often\ndifficult, due to a lack of empirical interatomic potentials (EIPs) for\ndifferent systems. As a result, this issue has become a major barrier to\nrealizing the promise associated with advanced atomistic level modeling\ntechniques. Here, we present a general method for specifically optimizing EIPs\nfrom ab initio inputs for the study of phonon transport properties, thereby\nresulting in phonon optimized potentials (POPs). The method uses a genetic\nalgorithm (GA) to directly fit to the key properties that determine whether or\nnot the atomic level dynamics and most notably the phonon transport are\ndescribed properly.",
        "positive": "Accessing the conduction band dispersion in CH3NH3PbI3 single crystals: The conduction band structure in methylammonium lead iodide (CH3NH3PbI3) was\nstudied both by angle-resolved two-photon photoemission spectroscopy (AR-2PPE)\nwith low-photon intensity and angle-resolved low-energy inverse photoelectron\nspectroscopy (AR-LEIPS). Clear energy dispersion of the conduction band along\nthe {\\Gamma}M direction was observed by these independent methods under\ndifferent temperatures, and the dispersion was found to be consistent with band\ncalculations under the cubic phase. The effective mass of the electrons at the\n{\\Gamma} point was estimated to be (0.20+-0.05)m0 at 90 K. The observed energy\nposition was largely different between the AR-LEIPS and AR-2PPE, demonstrating\nthe electron correlation effects on the band structures. The present results\nalso indicate that the surface structure in CH3NH3PbI3 provides the\ncubic-dominated electronic property even at lower temperatures."
    },
    {
        "anchor": "Mechanism of ferroelectric instabilities in non d^0 perovskites: LaCrO_3\n  versus CaMnO_3: The incompatibility of partial d occupation on the perovskite B-site with the\nstandard charge transfer mechanism for ferroelectricity has been a central\nparadigm in multiferroics research. Nevertheless, it was recently shown by\ndensity functional theory calculations that CaMnO_3 exhibits a polar\ninstability that even dominates over the octahedral tilting for slightly\nenlarged unit cell volume. Here, we present similar calculations for LaCrO_3,\nwhich has the same d^3 B-site electron configuration as CaMnO_3. We find that\nLaCrO_3 exhibits a very similar, albeit much weaker, polar instability as\nCaMnO_3. In addition, while the Born effective charge (BEC) of the Mn^{4+}\ncation in CaMnO_3 is highly anomalous, the BEC of Cr^{3+} in LaCrO_3 is only\nslightly enhanced. By decomposing the BECs into contributions of individual\nWannier functions we show that the ferroelectric instabilities in both systems\ncan be understood in terms of charge transfer between TM d and O p states,\nanalogously to the standard d^0 perovskite ferroelectrics.",
        "positive": "Global property prediction: A benchmark study on open source,\n  perovskite-like datasets: Screening combinatorial space for novel materials - such as perovskite-like\nones for photovoltaics - has resulted in a high amount of simulated\nhigh-troughput data and analysis thereof. This study proposes a comprehensive\ncomparison of structural-fingerprint based machine-learning models on seven\nopen-source databases of perovskite-like materials to predict bandgaps and\nenergies. It shows that none of the given methods are able to capture arbitrary\ndatabases evenly, while underlining that commonly used metrics are highly\ndatabase dependent in typical workflows. In addition the applicability of\nvariance selection and autoencoders to significantly reduce fingerprint size\nindicates that models built with common fingerprints only rely on a submanifold\nof the available fingerprint space."
    },
    {
        "anchor": "Computational study of structural and elastic properties of random\n  AlGaInN alloys: In this work we present a detailed computational study of structural and\nelastic properties of cubic AlGaInN alloys in the framework of Keating valence\nforce field model, for which we perform accurate parametrization based on state\nof the art DFT calculations. When analyzing structural properties, we focus on\nconcentration dependence of lattice constant, as well as on the distribution of\nthe nearest and the next nearest neighbour distances. Where possible, we\ncompare our results with experiment and calculations performed within other\ncomputational schemes. We also present a detailed study of elastic constants\nfor AlGaInN alloy over the whole concentration range. Moreover, we include\nthere accurate quadratic parametrization for the dependence of the alloy\nelastic constants on the composition. Finally, we examine the sensitivity of\nobtained results to computational procedures commonly employed in the Keating\nmodel for studies of alloys.",
        "positive": "Thermoelectric transport properties of electron doped pyrite FeS2: Pyrite FeS$_2$ has been investigated for a wide range of applications,\nincluding thermoelectrics due to previous observation of large thermopower at\nroom-temperature. However, the values of thermopower reported in the literature\nis extremely sensitive to the nature of sample -- whether they are natural or\nlab grown, bulk crystals or thin films -- and an ambiguity in the magnitude and\nsign of thermopower of pure FeS$_2$ exists. Variation in the magnitude of\nroom-temperature thermopower has also been observed in Co-doped samples.\nTherefore, it is of interest to clarify the intrinsic thermopower of this\nsystem that could be measured in more pure samples. In this paper, we\ninvestigate the thermoelectric properties of Co-doped FeS$_2$ using first\nprinciples calculations. We apply three different doping schemes to understand\nthe effect of electron doping in FeS$_2$, namely explicit Co-substitution,\njellium doping and electron addition within rigid band approximation (RBA)\npicture. The calculated thermopower is less than $-50$ $\\mu$V/K for all values\nof Co doping that we studied, suggesting that this system may not be useful in\nthermoelectric applications. Interestingly, we find that RBA substantially\noverestimates the magnitude of calculated thermopower compared to the explicit\nCo-substitution and jellium doping schemes. The overestimation occurs because\nthe changes in the electronic structure due to doping-induced structural\nmodification and charge screening is not taken into account by the rigid shift\nof the Fermi level within RBA. RBA is frequently used in first principles\ninvestigations of the thermopower of doped semiconductors, and Co-substituted\nFeS$_2$ illustrates a case where it fails."
    },
    {
        "anchor": "The melting behavior of lutetium aluminum perovskite LuAlO3: DTA measurements with mixtures of aluminum oxide and lutetium oxide around\nthe 1:1 perovskite composition were performed up to 1970 deg. C. A peak with\nonset 1901 deg C was due to the melting of the eutectic Lu4Al2O9 (monoclinic\nphase) and LuAlO3 (perovskite). Neither peritectic melting of the perovskite\nnor its decomposition in the solid phase could be resolved experimentally. The\nmaximum of the eutectic peak size is near x=0.44, on the Lu-rich side of the\nperovskite, which is consistent with the conclusion that LuAlO3 melts\nperitectically at ca. 1907 deg. C as proposed by Wu, Pelton, J. Alloys Compd.\n179 (1992) 259. Thermodynamic equilibrium calculations reveal, that under\nstrongly reducing conditions (oxygen partial pressure <10^{-13} bar)\naluminum(III) oxide can be reduced to suboxides or even Al metal. It is shown\nthat under such conditions a new phase field with liquid Al can appear.",
        "positive": "On the existence of ethylenediaminetetraacetic acid (EDTA) doped zinc\n  sulphate heptahydrate crystal: It is argued that the ethylenediaminetetraacetic acid (EDTA) doped zinc\nsulphate heptahydrate crystal reported by Raja et al Spectrochim Acta 99A\n(2012) 23 is the well known zinc sulphate heptahydrate."
    },
    {
        "anchor": "Phosphorescence by trapping defects in boric acid induced by thermal\n  processing: The phosphorescence of boric acid at room temperature is a puzzling\nphenomenon subject to controversial interpretations although the role of\nstructural defects has not yet been considered. Heat treatments of boric acid\ncause its transformation into the metaboric phase and amorphous boron oxide.\nThe structural changes after thermal processing can create defects that become\ncenters of luminescence and recombination channels in the visible range. In the\npresent work, we have thermally processed commercial boric acid at different\ntemperatures. Samples treated between 200 and 400{\\deg}C exhibit remarkable\nphosphorescence in the visible range. At around 480 and 528 nm, two distinct\nphosphorescent emissions occur, associated with trapped charge carriers\nrecombinations identified by thermoluminescence and electron paramagnetic\nresonance spectroscopy. Our structural and optical studies suggest that the\nactivation of boric acid phosphorescence after heat treatment is correlated\nwith the presence of defects. The afterglow results from a trapping and\ndetrapping process, which delays the recombination at the active optical\ncenters. Time-dependent density functional study of defective BOH molecules and\nclusters shows the emergence of near UV and blue optical transitions in\nabsorption. These defects trigger the photoluminescence in thermally processed\nboric acid samples.",
        "positive": "Resonant switching using spin valves: Using micromagnetics we demonstrate that the r.f. field produced by a spin\nvalve can be used to reverse the magnetization in a magnetic nanoparticle. The\nr.f. field is generated using a current that specifically excites a uniform\nspin wave in the spin valve. This current is swept such that the\nchirped-frequency generated by the valve matches the angular dependent resonant\nfrequency of the anisotropy-dominated magnetic nanoparticle, as a result of\nwhich the magnetization reversal occurs. The switching is fast, requires\ncurrents similar to those used in recent experiments with spin valves, and is\nstable with respect to small perturbations. This phenomenon can potentially be\nemployed in magnetic information storage devices or recently discussed magnetic\ncomputing schemes."
    },
    {
        "anchor": "Modernist Materials Synthesis: Finding Thermodynamic Shortcuts with\n  Hyperdimensional Chemistry: Synthesis remains a challenge for advancing materials science. A key focus of\nthis challenge is how to enable selective synthesis, particularly as it\npertains to metastable materials. This perspective addresses the question: how\ncan ``spectator'' elements, such as those found in double ion exchange\n(metathesis) reactions, enable selective materials synthesis? By observing\nreaction pathways as they happen (\\emph{in situ}) and calculating their\nenergetics using modern computational thermodynamics, we observe transient,\ncrystalline intermediates that suggest that many reactions attain a local\nthermodynamic equilibrium dictated by local chemical potentials far before\nachieving a global equilibrium set by the average composition. Using this\nknowledge, one can thermodynamically ``shortcut'' unfavorable intermediates by\nincluding additional elements beyond those of the desired target, providing\naccess to a greater number of intermediates with advantageous energetics and\nselective phase nucleation. Ultimately, data-driven modeling that unites\nfirst-principles approaches with experimental insights will refine the accuracy\nof emerging predictive retrosynthetic models for complex materials synthesis.",
        "positive": "Thermally driven spin and charge currents in thin NiFe2O4/Pt films: We present results on the longitudinal spin Seebeck effect (LSSE) shown by\nsemiconducting ferrimagnetic NiFe2O4/Pt films from room temperature down to 50K\nbase temperature. To the best of our knowledge, this is the first observation\nof spin caloric effect in NiFe2O4 thin films. The temperature dependence of the\nconductivity has been studied in parallel to obtain information about the\norigin of the electric potentials detected at the Pt coverage of the\nferrimagnet in order to distinguish the LSSE from the anomalous Nernst effect.\nFurthermore, the dependence of the LSSE on temperature gradients as well as the\ninfluence of an external magnetic field direction is investigated."
    },
    {
        "anchor": "Metalloboranes from first-principles calculations: A candidate for\n  high-density hydrogen storage: Using first principles calculations, we show the high hydrogen storage\ncapacity of a new class of compounds, metalloboranes. Metalloboranes are\ntransition metal (TM) and borane compounds that obey a novel-bonding scheme. We\nhave found that the transition metal atoms can bind up to 10 H2 molecules.",
        "positive": "Hetero-epitaxial EuO Interfaces Studied by Analytic Electron Microscopy: With nearly complete spin polarization, the ferromagnetic semiconductor\neuropium monoxide could enable next-generation spintronic devices by providing\nefficient ohmic spin injection into silicon. Spin injection is greatly affected\nby the quality of the interface between the injector and silicon. Here, we use\natomic-resolution scanning transmission electron microscopy in conjunction with\nelectron energy loss spectroscopy to directly image and chemically characterize\na series of EuO|Si and EuO|YAlO3 interfaces fabricated using different growth\nconditions. We identify the presence of europium silicides and regions of\ndisorder at the EuO|Si interfaces, imperfections that could significantly\nreduce spin injection efficiencies via spin-flip scattering."
    },
    {
        "anchor": "In-situ NMR Measurements of Vapor Deposited Ice: In-situ NMR spin-lattice relaxation measurements were performed on several\nvapor deposited ices. The measurements, which span more than 6 orders of\nmagnitude in relaxation times, show a complex spin-lattice relaxation pattern\nthat is strongly dependent on the growth conditions of the sample. The\nrelaxation patterns change from multi-timescale relaxation for samples grown at\ntemperatures below the amorphous-crystalline transition temperature to single\nexponential recovery for samples grown above the transition temperature. The\nslow-relaxation contribution seen in cold-grown samples exhibits a temperature\ndependence, and becomes even slower after the sample is annealed at 200K. The\nfast-relaxation contribution seen in these samples, does not seem to change or\ndisappear even when heating to temperatures where the sample is evaporated. The\npossibility that the fast relaxation component is linked to the microporous\nstructures in amorphous ice samples is further examined using an environmental\nelectron scanning microscope. The images reveal complex meso-scale microporous\nstructures which maintain their morphology up to their desorption temperatures.\nThese findings, support the possibility that water molecules at pore surfaces\nmight be responsible for the fast-relaxation contribution. Furthermore, the\nresults of this study indicate that the pore-collapse dynamics observed in the\npast in amorphous ices using other experimental techniques, might be\neffectively inhibited in samples which are grown by relatively fast vapor\ndeposition.",
        "positive": "Electronic and Magnetic Characterization of Epitaxial VSe$_2$ Monolayers\n  on Superconducting NbSe$_2$: Vertical integration of two-dimensional (2D) van der Waals (vdW) materials\nwith different quantum ground states is predicted to lead to novel electronic\nproperties that are not found in the constituent layers. Here, we present the\ndirect synthesis of superconductor-magnet hybrid heterostructures by combining\nsuperconducting niobium diselenide (NbSe$_2$) with the monolayer (ML) vanadium\ndiselenide (VSe$_2$). More significantly, the in-situ growth in ultra-high\nvacuum (UHV) allows to produce a clean and an atomically sharp interfaces.\nCombining different characterization techniques and density-functional theory\n(DFT) calculations, we investigate the electronic and magnetic properties of\nVSe$_2$ on NbSe$_2$. Low temperature scanning tunneling microscopy (STM)\nmeasurements demonstrate a reduction of the superconducting gap on VSe$_2$\nlayer. This together with the lack of charge density wave signatures indicates\nmagnetization of the sheet, but not of a conventional itinerant ferromagnet."
    },
    {
        "anchor": "Magnetic Proximity Effects in Transition-Metal Dichalcogenides:\n  Converting Excitons: The two-dimensional character and reduced screening in monolayer\ntransition-metal dichalcogenides (TMDs) lead to the ubiquitous formation of\nrobust excitons with binding energies orders of magnitude larger than in bulk\nsemiconductors. Focusing on neutral excitons, bound electron-hole pairs, that\ndominate the optical response in TMDs, it is shown that they can provide\nfingerprints for magnetic proximity effects in magnetic heterostructures. These\nproximity effects cannot be described by the widely used single-particle\ndescription, but instead reveal the possibility of a conversion between\noptically inactive and active excitons by rotating the magnetization of the\nmagnetic substrate. With recent breakthroughs in fabricating Mo- and W-based\nmagnetic TMD-heterostructures, this emergent optical response can be directly\ntested experimentally.",
        "positive": "Electronic structure of Mu-complex donor state in rutile TiO$_2$: The hyperfine structure of the interstitial muonium (Mu) in rutile (TiO$_2$,\nweakly $n$-type) has been identified by means of a muon spin rotation\ntechnique. The angle-resolved hyperfine parameters exhibit a tetragonal\nanisotropy within the $ab$ plane and axial anisotropy with respect to the\n$\\langle 001\\rangle$ ($\\hat{c}$) axis. This strongly suggests that the Mu is\nbound to O (forming an OH bond) at an off-center site within a channel along\nthe $\\hat{c}$ axis, while the unpaired Mu electron is localized around the\nneighboring Ti site. The hyperfine parameters are quantitatively explained by a\nmodel that considers spin polarization of the unpaired electron at both the Ti\nand O sites, providing evidence for the formation of Mu as a Ti-O-Mu complex\nparamagnetic state. The disappearance of the Mu signal above $\\sim$10 K\nsuggests that the energy necessary for the promotion of the unpaired electron\nto the conduction band by thermal activation is of the order of $10^1$ meV.\nThese observations suggest that, while the electronic structure of Mu (and\nhence H) differs considerably from that of the conventional shallow level donor\ndescribed by the effective mass model, Mu supplies a loosely bound electron,\nand thus, serves as a donor in rutile."
    },
    {
        "anchor": "Anisotropy effects on Rashba and topological insulator spin polarized\n  surface states: a unified phenomenological description: Spin polarized two-dimensional electronic states have been previously\nobserved on metallic surface alloys with giant Rashba splitting and on the\nsurface of topological insulators. We study the surface band structure of these\nsystems, in a unified manner, by exploiting recent results of k.p theory. The\nmodel suggests a different way to address the effect of anisotropy in Rashba\nsystems. Changes in the surface band structure of various Rashba compounds can\nbe captured by a single effective parameter which quantifies the competition\nbetween the Rashba effect and the hexagonal warping of the constant energy\ncontours. The same model provides a unified phenomenological description of the\nsurface states belonging to materials with topologically trivial and\nnon-trivial band structures.",
        "positive": "Na2V3O7, a frustrated nanotubular system with spin-1/2 diamond rings: Following the recent discussion on the puzzling nature of the interactions in\nthe nanotubular system Na2V3O7, we present a detailed ab-initio microscopic\nanalysis of its electronic and magnetic properties. By means of a non-trivial\ndownfolding study we propose an effective model in terms of tubes of nine-site\nrings with the geometry of a spin-diamond necklace with frustrated inter-ring\ninteractions. We show that this model provides a quantitative account of the\nobserved magnetic behavior."
    },
    {
        "anchor": "Plasmonic excitations in noble metals: The case of Ag: The delicate interplay between plasmonic excitations and interband\ntransitions in noble metals is described by means of {\\it ab initio}\ncalculations and a simple model in which the conduction electron plasmon is\ncoupled to the continuum of electron-hole pairs. Band structure effects,\nspecially the energy at which the excitation of the $d$-like bands takes place,\ndetermine the existence of a subthreshold plasmonic mode, which manifests\nitself in Ag as a sharp resonance at 3.8 eV. However, such a resonance is not\nobserved in the other noble metals. Here, this different behavior is also\nanalyzed and an explanation is provided.",
        "positive": "Spin Spirals in Surface Alloys on Ru(0001): A First-principles Study: We have used ab initio density functional theory to compute the magnetic\nground states of the surface alloy systems FeAu$_2$/Ru(0001) and\nMnAu$_2$/Ru(0001). For both systems, we find that the lowest energy magnetic\nconfiguration corresponds to a left-rotating spin spiral, in which the sense of\nrotation is determined by the Dzyaloshinskii-Moriya interaction. These spirals\nare lower in energy than the ferromagnetic configuration by 3-4 meV per nm$^2$.\nWe also find that FeAu$_2$/Ru(0001) has a significantly high magnetic\nanisotropy energy, of the order 1 meV per Fe atom. By comparing with the\ncorresponding freestanding alloy monolayers, we find that the presence of the\nRu substrate plays a significant role in determining the magnetic properties of\nthe surface alloy systems."
    },
    {
        "anchor": "On the high accuracy lattice-parameters determination by n-beam\n  diffraction: Theory and application to the InAs quantum dots grown over\n  GaAs(001) substrate system: Ultra-precise lattice parameter measurements in single crystals are\nachievable, in principle, by X-ray multiple diffraction (XMD) experiments. Tiny\nsample misalignments have hindered the systematic usage of XMD in studies where\naccuracy is an important issue. In this work, theoretical basement and methods\nfor correcting general misalignment errors are presented. As a practical\ndemonstration, the induced strain of buried InAs quantum dots grown on GaAs\n(001) substrates is determined. Such a demonstration confirms the possibility\nto investigate epitaxial nanostructures via the strain field that they generate\nin the substrate crystalline lattice.\n  This work was supported by the Brazilian founding agencies FAPESP (grant\nnumbers 02/10185-3 and 02/10387-5), CNPq (proc. number 301617/95-3 and\n150144/03-2) and LNLS (under proposal number D12A-XRD1 2490/03).",
        "positive": "Evaluation of the AMOEBA force field for simulating metal halide\n  perovskites in the solid state and in solution: In this work, we compare existing non-polarizable force fields developed to\nstudy the solid or solution phases of hybrid organic-inorganic halide\nperovskites with the AMOEBA polarizable force field. The aim is to test whether\nmore computationally expensive polarizable force fields like AMOEBA offer\nbetter transferability between solution and solid phases, with the ultimate\ngoal being the study of crystal nucleation, growth and other interfacial\nphenomena involving these ionic compounds. In the context of hybrid\nperovskites, AMOEBA force field parameters already exist for several elements\nin solution and we decided to leave them unchanged and to only parameterize the\nmissing ones (Pb\\textsuperscript{2+} and\nCH\\textsubscript{3}NH\\textsubscript{3}\\textsuperscript{+} ions) in order to\nmaximise transferability and avoid over-fitting to the specific examples\nstudied here. Overall, we find that AMOEBA yields accurate hydration free\nenergies (within 5\\%) for typical ionic species while showing the correct\nordering of stability for the different crystal polymorphs of\nCsPbI\\textsubscript{3} and\nCH\\textsubscript{3}NH\\textsubscript{3}PbI\\textsubscript{3}. While the existing\nparameters do not accurately reproduce all transition temperatures and lattice\nparameters, AMOEBA offers better transferability between solution and solid\nstates than existing non-polarizable force fields."
    },
    {
        "anchor": "The Equivalence Between Unit-Cell Twinning and Tiling in Icosahedral\n  Quasicrystals: It is shown that tiling in icosahedral quasicrystals can also be properly\ndescribed by cyclic twinning at the unit cell level. The twinning operation is\napplied on the primitive prolate golden rhombohedra, which can be considered a\nresult of a distorted face-centered cubic parent structure. The shape of the\nrhombohedra is determined by an exact space filling, resembling the forbidden\nfive-fold rotational symmetry. Stacking of clusters, formed around multiply\ntwinned rhombic hexecontahedra, keeps the rhombohedra of adjacent clusters in\ndiscrete relationships. Thus periodicities, interrelated as members of a\nFibonacci series, are formed. The intergrown twins form no obvious twin\nboundaries and fill the space in combination with the oblate golden\nrhombohedra, formed between clusters in contact. Simulated diffraction patterns\nof the multiply twinned rhombohedra and the Fourier transform of an extended\nmodel structure are in full accord with the experimental diffraction patterns\nand can be indexed by means of three-dimensional crystallography.",
        "positive": "Influence of nanoscale regions on Raman spectra of complex perovskites: New approach on interpretation and processing of Raman spectra of complex\nperovskites is suggested. Raman spectra of $PbMg_{1/3}Nb_{2/3}O_{3}$ and $%\nPbSc_{1/2}Ta_{1/2}O_{3}$ are successfully described on the basis of the\nphonon-confinement model and validity of the method is demonstrated on good\nagreement of experimentally obtained and computer simulated spectra of another\ncomplex perovskite, $BaMg_{1/3}Ta_{2/3}O_{3}$. The study showed that the size\nof nanoscale regions is a kind of an inborn characteristic of the sample and is\nnot temperature dependent. For $PbSc_{1/2}Ta_{1/2}O_{3}$, two special\ntemperature points, approximately 400 K and 600 K are found from the analysis\nof the temperature behaviour of obtained mode parameters."
    },
    {
        "anchor": "Deposition of La2Zr2O7 Film by Chemical Solution Deposition: La2Zr2O7 (LZO) formation of bulk powders and of films by Chemical Solution\nDeposition (CSD) process have been studied using propionates. The treatment\ninvolved a one step cycle in the reducing forming gas (Ar-5%H2) to be\ncompatible with Ni-5at%W RABITS. Large amount of residual carbon was found in\nLZO powders formed in these conditions (10 wt %). The volume fraction of the\ncube texture in LZO films on Ni-5at%w RABITS was found to be a function of the\nspeed of the gas flown above sample. This phenomenon is discussed in\nconsidering the C deposited from the carbon-containing gases emitted during the\npyrolysis of the precursor. Using proper conditions (950 ^\\circC and the speed\nof gas of 6.8\\times10^{-2} m/s), LZO films with good surface crystallinity\ncould be obtained on Ni-5at%W RABITS as demonstrated by X-ray diffraction,\nelectron backscattered diffraction and RHEED. The existence of residual carbon\nin oxide films is a common question to films deposited by CSD processes under\nreducing condition.",
        "positive": "The role of intrinsic atomic defects in a Janus MoSSe/XN (X = Al, Ga)\n  heterostructure: a first principles study: The interactions between different layers in van der Waals heterostructures\nhave a significant impact on the electronic and optical characteristics. By\nutilizing the intrinsic dipole moment of Janus transition metal dichalcogenides\n(TMDs), it is possible to tune these interlayer interactions. We systematically\ninvestigate structural and electronic properties of Janus MoSSe\nmonolayer/graphene-like Aluminum Nitrides (MoSSe/g-AlN) heterostructures with\npoint defects by employing density functional theory calculations with the\ninclusion of the nonlocal van der Waals correction. The findings indicate that\nthe examined heterostructures are energetically and thermodynamically stable,\nand their electronic structures can be readily modified by creating a\nheterostructure with the defects in g-AlN monolayer. This heterostructure\nexhibits an indirect semiconductor with the band gap of 1.627 eV which is in\nthe visible infrared region. It can be of interest for photovoltaic\napplications. When a single N atom or Al atom is removed from a monolayer of\ng-AlN in the heterostructure, creating vacancy defects, the material exhibits\nsimilar electronic band structures with localized states within the band gap\nwhich can be used for deliberately tailoring the electronic properties of the\nMoSSe/g-AlN heterostructure. These tunable results can offer exciting\nopportunities for designing nanoelectronics devices based on MoSSe/g-AlN\nheterojunctions."
    },
    {
        "anchor": "Optical conductivity of hydrogenated graphene from first principles: We investigate the effect of hydrogen coverage on the optical conductivity of\nsingle-side hydrogenated graphene from first principles calculations. To\naccount for different degrees of uniform hydrogen coverage we calculate the\ncomplex optical conductivity for graphene supercells of various sizes, each\ncontaining a single additional hydrogen atom. We use the linearized augmented\nplane wave (LAPW) method, as implemented in the WIEN2k density functional\ntheory code, to show that the hydrogen coverage strongly influences the complex\noptical conductivity and thus the optical properties, such as absorption, of\nhydrogenated graphene. We find that the optical conductivity of graphene in the\ninfrared, visible, and ultraviolet range has different characteristic features\ndepending on the degree of hydrogen coverage. This opens up new possibilities\nto tailor the optical properties of graphene by reversible hydrogenation, and\nto determine the hydrogen coverage of hydrogenated graphene samples in the\nexperiment by contact-free optical absorption measurements.",
        "positive": "Giant $g$-factors of Natural Impurities in Synthetic Quartz: We report the observation of $g$-factors of natural paramagnetic impurities\nin a pure synthetic quartz crystal at milli-Kelvin temperatures. Measurements\nare made by performing spectroscopy using multiple high-$Q$ Whispering Gallery\nModes sustained in the crystal. Extreme sensitivity of the method at low\ntemperatures allows the determination of natural residual impurities introduced\nduring the crystal growth. We observe $g$-factors that significantly differ\nfrom integer multiples of the electron $g$-factor in vacuum, and with values of\nup to $7.6$, which reveals much stronger coupling between impurities and the\ncrystal lattice than in previous studies. Both substitutional and interstitial\nions are proposed as candidates for the observed interactions."
    },
    {
        "anchor": "Exploration of stable compounds, crystal structures, and\n  superconductivity in the Be-H system: Using first-principles variable-composition evolutionary methodology, we\nexplored the high-pressure structures of beryllium hydrides between 0 and 400\nGPa. We found that BeH$_2$ remains the only stable compound in this pressure\nrange. The pressure-induced transformations are predicted as $Ibam$\n$\\rightarrow $ $P\\bar{3}m1$ $\\rightarrow $ $R\\bar{3}m$ $ \\rightarrow $ $Cmcm$ $\n\\rightarrow $ $P4/nmm$, which occur at 24, 139, 204 and 349 GPa, respectively.\n$P\\bar{3}m1$ and $R\\bar{3}m$ structures are layered polytypes based on close\npackings of H atoms with Be atoms filling octahedral voids in alternating\nlayers. $Cmcm$ and $P4/nmm$ structures have 3D-networks of strong bonds, but\nalso feature rectanular and squre, respectively, layers of H atoms with short\nH-H distances. $P\\bar{3}m1$ and $R\\bar{3}m$ are semiconductors while $Cmcm$ and\n$P4/nmm$ are metallic. We have explored superconductivity of both metallic\nphases, and found large electron-phonon coupling parameters of $ \\lambda $=0.63\nfor $Cmcm$ (resulting in a $T_c$ of 32.1-44.1 K) at 250 GPa and $ \\lambda\n$=0.65 for $P4/nmm$ ($T_c$ = 46.1-62.4 K) at 400 GPa. The dependence of $T_c$\non pressure indicates that $T_c$ initially increases to a maximum of 45.1 K for\n$Cmcm$ at 275 GPa and 97.0 K for $P4/nmm$ at 365 GPa, and then decreases with\nincreasing pressure for both phases.",
        "positive": "Electrical and thermal conductivities of reduced graphene\n  oxide/polystyrene composites: The author reports an experimental study of electrical and thermal transport\nin reduced graphene oxide (RGO)/polystyrene (PS) composites. The electrical\nconductivity ($\\sigma$) of RGO/PS composites with different RGO concentrations\nat room temperature shows a percolation behavior with the percolation threshold\nof ~ 0.25 vol.%. Their temperature-dependent electrical conductivity follows\nEfros-Shklovskii (ES) variable range hopping (VRH) conduction in the\ntemperature range of 30 to 300 K. The thermal conductivity ($\\kappa$) of\ncomposites is enhanced by ~ 90 % as the concentration is increased from 0 to 10\nvol.%. The thermal conductivity of composites approximately linearly increases\nwith increasing temperature from 150 to 300 K. Composites with a higher\nconcentration show a stronger temperature dependence in the thermal\nconductivity."
    },
    {
        "anchor": "Giant anisotropic magnetostriction in Pr$_{0.5}$Sr$_{0.5}$MnO$_3$: Magnetic, linear thermal expansion (LTE), anisotropic ($\\lambda_t$) and\nvolume ($\\omega $) magnetostriction properties of Pr$_{0.5}$Sr$_{0.5}$MnO$_3$\nwere investigated. The LTE decreases smoothly from 300 K without a clear\nanomaly either around the Curie (T$_C$ = 270 K) or the Neel temperature (T$_N$\n= 100 K) and it exhibits hysteresis over a wide temperature range (60 K-270 K)\nupon warming. Isothermal magnetization study suggests that 13 % of the\nferromagnetic phase coexists with 87 % of the antiferromagnetic phase at 25 K.\nThe parallel and perpendicular magnetostrictions undergo rapid changes during\nthe metamagnetic transition. Contrary to the isotropic giant volume\nmagnetostriction reported in manganites so far, this compound exhibits a giant\nanisotropic magnetostriction ($\\lambda_t \\approx 10^{-3}$) and smaller volume\n($\\omega \\approx 10^{-4}$) magnetostrictions below T$_N$. We suggest that the\nfield induced antiferromagnetic to ferromagnetic transition is accompanied by a\nstructural transition from the d$_{x^2-y^2}$ orbital ordered antiferromagnetic\n(orthorhombic) to the orbital disordered ferromagnetic (tetragonal) phase. The\nmetamagnetic transition proceeds through nucleation and growth of the\nferromagnetic domains at the expense of the antiferromagnetic phase. The\npreferential orientation of the ferromagnetic (tetragonal) domains along the\nfield direction increases the linear dimension of the sample in the field\ndirection and decreases in the orthogonal direction leading to the observed\ngiant anisotropic magnetostriction effect. Our study also suggests that\nnanodomains of the low temperature antiferromagnetic phase possibly exist in\nthe temperature region T$_N$ < T < T$_C$.",
        "positive": "Ab initio Calculations of the Vibrational Modes of MnAs and Ga1-xMnxAs: In this work, we present our theoretical results for the equation of state\nand the phonon dispersions of MnAs, as well as the Mn concentration dependence\nof both the lattice parameter and the phonon frequencies of the cubic GaMnAs\nalloys. The results are in good agreement with the experimental results\nwhenever this comparison is possible. Based on the obtained results, the\nlattice constants and the phonon frequencies of the alloys do not obey the\nVegard rule."
    },
    {
        "anchor": "Environment Dependent Interatomic Potential for Bulk Silicon: We use recent theoretical advances to develop a new functional form for\ninteratomic forces in bulk silicon. The theoretical results underlying the\nmodel include a novel analysis of elastic properties for the diamond and\ngraphitic structures and inversions of ab initio cohesive energy curves. The\ninteraction model includes two-body and three-body terms which depend on the\nlocal atomic environment through an effective coordination number. This\nformulation is able to capture successfully: (i) the energetics and elastic\nproperties of the ground state diamond lattice; (ii) the covalent\nre-hybridization of undercoordinated atoms; (iii) and a smooth transition to\nmetallic bonding for overcoordinated atoms. Because the essential features of\nchemical bonding in the bulk are built into the functional form, this model\npromises to be useful for describing interatomic forces in silicon bulk phases\nand defects. Although this functional form is remarkably realistic by usual\nstandards, it contains a small number of fitting parameters and requires\ncomputational effort comparable to the most efficient existing models. In a\ncompanion paper, a complete parameterization of the model is given, and\nexcellent performance for condensed phases and bulk defects is demonstrated.",
        "positive": "Parent grain reconstruction from partially or fully transformed\n  microstructures in MTEX: A versatile generic framework for parent grain reconstruction from fully or\npartially transformed child microstructures was integrated into the open-source\ncrystallographic toolbox MTEX. The framework extends traditional parent grain\nreconstruction, phase transformation and variant analysis to all parent-child\ncrystal symmetry combinations. The inherent versatility of the universally\napplicable parent grain reconstruction methods, and the ability to conduct\nin-depth variant analysis are showcased via example workflows that can be\nprogrammatically modified by users to suit their specific applications. This is\nhighlighted by three applications namely, $\\alpha$-to-$\\gamma$ reconstruction\nin a lath martensitic steel, $\\alpha$-to-$\\beta$ reconstruction in a Ti alloy,\nand a two-step reconstruction from $\\alpha$-to-$\\varepsilon$-to-$\\gamma$ in a\ntwinning and transformation -induced plasticity steel. Advanced orientation\nrelationship discovery and analysis options, including variant analysis, is\ndemonstrated via the add-on function library, ORTools."
    },
    {
        "anchor": "Extraction of Isotropic Electron-Nuclear Hyperfine Coupling Constants of\n  Paramagnetic Point Defects from Near-Zero Field Magnetoresistance Spectra via\n  Least Squares Fitting to Models Developed from the Stochastic Quantum\n  Liouville Equation: We report on a method by which we can systematically extract spectroscopic\ninformation such as isotropic electron-nuclear hyperfine coupling constants\nfrom near-zero field magnetoresistance spectra. The method utilizes a least\nsquares fitting of models developed from the stochastic quantum Liouville\nequation. We applied our fitting algorithm to two distinct material systems:\nSi/SiO2 MOSFETs, and a-Si:H MIS capacitors. Our fitted results and hyperfine\nparameters are in reasonable agreement with existing knowledge of the defects\npresent in the systems. Our work indicates that the NZFMR response and fitting\nof the NZFMR spectrum via models developed from the stochastic quantum\nLiouville equation could be a relatively simple yet powerful addition to the\nfamily of spin-based techniques used to explore the chemical and structural\nnature of point defects in semiconductor devices and insulators.",
        "positive": "Electrically-detected magnetic resonance in ion-implanted Si:P\n  nanostructures: We present the results of electrically-detected magnetic resonance (EDMR)\nexperiments on silicon with ion-implanted phosphorus nanostructures, performed\nat 5 K. The devices consist of high-dose implanted metallic leads with a square\ngap, into which Phosphorus is implanted at a non-metallic dose corresponding to\n10^17 cm^-3. By restricting this secondary implant to a 100 nm x 100 nm region,\nthe EDMR signal from less than 100 donors is detected. This technique provides\na pathway to the study of single donor spins in semiconductors, which is\nrelevant to a number of proposals for quantum information processing."
    },
    {
        "anchor": "Strain induced band gap deformation of H/F passivated graphene and h-BN\n  sheet: Strain induced band gap deformations of hydrogenated/fluorinated graphene and\nhexagonal BN sheet have been investigated using first principles density\nfunctional calculations. Within harmonic approximation, the deformation is\nfound to be higher for hydrogenated systems than for the fluorinated systems.\nInterestingly, our calculated band gap deformation for hydrogenated/fluorinated\ngraphene and BN sheets are positive, while those for pristine graphene and BN\nsheet are found to be negative. This is due to the strong overlap between\nnearest neighbor {\\pi} orbitals in the pristine sheets, that is absent in the\npassivated systems. We also estimate the intrinsic strength of these materials\nunder harmonic uniaxial strain, and find that the in-plane stiffness of\nfluorinated and hydrogenated graphene are close, but larger in magnitude as\ncompared to those of fluorinated and hydrogenated BN sheet.",
        "positive": "Room temperature charge-to-spin conversion from q-2DEG at SrTiO3-based\n  interfaces: Interfacial two-dimensional electron gas (2DEG), especially the SrTiO3-based\nones at the unexpected interface of insulators, have emerged to be a promising\ncandidate for efficient charge-spin current interconversion. In this article,\nto gain insight into the mechanism of the charge-spin current interconversion\nat the oxide-based 2DEG, we focused on conducting interfaces between insulating\nSrTiO3 and two types of aluminium-based amorphous insulators, namely SrTiO3/AlN\nand SrTiO3/Al2O3, and estimated their charge-spin conversion efficiency,\n{\\theta}_cs. The two types of amorphous insulators were selected to explicitly\nprobe the overlooked contribution of oxygen vacancy to the {\\theta}_cs. We\nproposed a mechanism to explain results of spin-torque ferromagnetic resonance\n(ST-FMR) measurements and developed an analysis protocol to reliably estimate\nthe {\\theta}_cs of the oxide based 2DEG. The resultant {\\theta}_cs/t, where t\nis the thickness of the 2DEG, were estimated to be 0.244 nm-1 and 0.101 nm-1\nfor the SrTiO3/AlN and SrTiO3/Al2O3, respectively, and they are strikingly\ncomparable to their crystalline counterparts. Furthermore, we also observe a\nlarge direct current modulation of resonance linewidth in SrTiO3/AlN samples,\nconfirming its high {\\theta}_cs and attesting an oxygen-vacancy-enabled\ncharge-spin conversion. Our findings emphasize the defects' contribution to the\ncharge-spin interconversion, especially in the oxide-based low dimensional\nsystems, and provide a way to create and enhance charge-spin interconversion\nvia defect engineering."
    },
    {
        "anchor": "Reduced Density Matrix Functional for Many-Electron Systems: Reduced density matrix functional theory for the case of solids is presented\nand a new exchange correlation functional based on a fractional power of the\ndensity matrix is introduced. We show that compared to other functionals, this\nproduces more accurate results for both finite systems. Moreover, it captures\nthe correct band gap behavior for conventional semiconductors as well as\nstrongly correlated Mott insulators, where a gap is obtained in absence of any\nmagnetic ordering.",
        "positive": "Observation of Effective Pseudospin Scattering in ZrSiS: 3D Dirac semimetals are an emerging class of materials that possess\ntopological electronic states with a Dirac dispersion in their bulk. In\nnodal-line Dirac semimetals, the conductance and valence bands connect along a\nclosed path in momentum space, leading to the prediction of pseudospin vortex\nrings and pseudospin skyrmions. Here, we use Fourier transform scanning\ntunneling spectroscopy (FT-STS) at 4.5 K to resolve quasiparticle interference\n(QPI) patterns at single defect centers on the surface of the line nodal\nsemimetal zirconium silicon sulfide (ZrSiS). Our QPI measurements show\npseudospin conservation at energies close to the line node. In addition, we\ndetermine the Fermi velocity to be $\\hbar v_F = 2.65 \\pm 0.10$ eV {\\AA} in the\n{\\Gamma}-M direction ~300 meV above the Fermi energy $E_F$, and the line node\nto be ~140 meV above $E_F$. More importantly, we find that certain scatterers\ncan introduce energy-dependent non-preservation of pseudospins, giving rise to\neffective scattering between states with opposite valley pseudospin deep inside\nvalence and conduction bands. Further investigations of quasiparticle\ninterference at the atomic level will aid defect engineering at the synthesis\nlevel, needed for the development of lower-power electronics via\ndissipationless electronic transport in the future."
    },
    {
        "anchor": "Boundary-induced phase in epitaxial iron layers: We report the discovery of a boundary-induced body-centered tetragonal (bct)\niron phase in thin films deposited on MgAl$_{2}$O$_{4}$ ($001$) substrates. We\npresent evidence for this phase using detailed x-ray analysis and ab-initio\ndensity functional theory calculations. A lower magnetic moment and a rotation\nof the easy magnetisation direction are observed, as compared to body-centered\ncubic (bcc) iron. Our findings expand the range of known crystal and magnetic\nphases of iron, providing valuable insights for the development of\nheterostructure devices using ultra-thin iron layers.",
        "positive": "EPR studies of the 105 K phase transition in SrTiO3 with the non-cubic\n  Fe5+ as local probe and a reinterpretation of other Fe5+ centres: The 105 K second-order displacive phase transition of SrTiO3 has been studied\nwith the help of Electron Paramagnetic Resonance. The photochromic non-cubic\nFe5+ centre is used as local probe. Critical phenomena, characterized by an\nexponent {\\beta} = 1/3, are presented. Line broadening effects are interpreted\nas stemming from time-dependent fluctuations near the phase transition point.\nThe data are consistent with those reported earlier on the Fe3+-VO pair centre,\nindicating cooperative effects in the crystal. Also a model for the non-cubic\nFe5+ is proposed, i.e., the ion is substitutional for Ti4+ with an empty\nadjacent expanded octahedron. Other Fe5+ centres in SrTiO3 and BaTiO3 are\nreviewed and reinterpreted."
    },
    {
        "anchor": "Spin-to-charge conversion by spin pumping in sputtered polycrystalline\n  Bi$_x$Se$_{1-x}$: Topological materials are of high interest due to the promise to obtain low\npower and fast memory devices based on efficient spin-orbit torque switching or\nspin-orbit magnetic state read-out. In particular, sputtered polycrystalline\nBi$_x$Se$_{1-x}$ is one of the materials with more potential for this purpose\nsince it is relatively easy to fabricate and has been reported to have a very\nhigh spin Hall angle. We study the spin-to-charge conversion in\nBi$_x$Se$_{1-x}$ using the spin pumping technique coming from the ferromagnetic\nresonance in a contiguous permalloy thin film. We put a special emphasis on the\ninterfacial properties of the system. Our results show that the spin Hall angle\nof Bi$_x$Se$_{1-x}$ has an opposite sign to the one of Pt. The charge current\narising from the spin-to-charge conversion is, in contrast, lower than Pt by\nmore than one order of magnitude. We ascribe this to the interdiffusion of\nBi$_x$Se$_{1-x}$ and permalloy and the changes in chemical composition produced\nby this effect, which is an intrinsic characteristic of the system and is not\nconsidered in many other studies.",
        "positive": "A first principles metal-semiconductor interaction study: Aluminum\n  adsorption on Ga-rich GaAs(100)-(2x1) and beta(4x2) surfaces: Ab initio self-consistent total energy calculations using second order\nMoller-Plesset perturbation theory and Hay-Wadt effective core potentials with\nassociated basis sets (HWECP's) for gallium and arsenic have been used to\ninvestigate the chemisorption properties of atomic aluminum on the Ga-rich\nGaAs(100)-(2x1) and beta(4x2) surfaces. Finite sized hydrogen saturated\nclusters with the experimental zinc-blende lattice constant of 5.654 ang. and\nthe energy optimized Ga dimer bond length of 2.758 ang. have been used to model\nthe semiconductor surface. To investigate the effects of the core electrons of\naluminum in the adsorption process, we have represented the Al adatom with both\nHWECP's and an all electron 6-311++G** basis set. Detailed energetics of\nchemisorption on the (100) surface layer including adsorption beneath the\nsurface layer at an interstitial site are investigated. Mulliken population\nanalysis and highest occupied molecular orbital-lowest unoccupied molecular\norbital (HOMO-LUMO) gaps are reported for all considered sites of\nchemisorption."
    },
    {
        "anchor": "A Novel Proposal for Manufacturing Steel: OSRAM's CO$_2$ Steel Making\n  Process: In this paper, we propose a concept to utilise Carbon-dioxide for\nSteel-Making and would like to name it after the first author as\nOSRAM-CO$_2$-SM process. We found in our lab experiments that the carbon\ncontent in high-carbon ferro-chrome metallic powders has come down from 7% to\n1% when pure CO$_2$ gas with partial pressure of 1 atmosphere is passed through\na horizontal retort furnace maintained at 1100$^o$ C for 24 hours. Our results\nclearly demonstrated that decarburisation can be very effective, when CO$_2$ is\nused at temperatures where it is unstable and the Boudouard reaction which is\nendothermic in nature is more favoured. Based on these findings, we propose the\nOSRAM-CO$_2$-SM process in which CO$_2$ shall be used as the decarburising\nagent. CO$_2$ is to be passed into a specially designed converter provided with\nheating mechanism to maintain the contents from blast furnace in a molten state\nfor decarburisation of the melt. The out coming hot gases consisting of CO has\nto be burnt in a combustion chamber with stochiometric proportions of pure\nO$_2$ to produce CO$_2$ at a partial pressure close to 1 atm.The process will\nbe extremely useful as it involves reuse and recycle of CO$_2$ and in turn\nwould reduce the overall amount of CO$_2$ discharged into the atmosphere.",
        "positive": "First-principles study of the magnetic anisotropy of ultrathin B-, C-,\n  and N-doped FeCo films: Iron-based layered systems are of great interest because of their ability to\ntune effective material parameters such as magnetic anisotropy energy (MAE).\nThe influence of the crystallographic structure of Fe, its thickness, and the\npresence of other layers above and below the Fe layer on magnetic parameters,\nsuch as the MAE of the studied system, is an intriguing and important topic\nfrom an application point of view. Here, we present a density functional theory\n(DFT) study of the magnetic anisotropy of nine-monolayer Fe, FeCo, and FeCo\nfilms with B, C, and N dopants placed in octahedral interstitial positions. The\ntheoretical study is based on calculations using the full-potential\nlocal-orbital code FPLO and the generalized gradient approximation. The\nchemical disorder in the FeCo layers was modeled using the virtual crystal\napproximation. The structures of the layers were subjected to optimization of\nthe geometry of the interlayer spacings and the neighborhood of the dopant\nsites. We determined the local magnetic moments and the excess charge at each\nlayer position. We also identified the influence of dopant atoms on the\nmagnetic properties of FeCo layers, such as magnetization and magnetic\nanisotropy."
    },
    {
        "anchor": "Thickness Dependent Parasitic Channel Formation at AlN/Si Interfaces: The performance of GaN-on-Silicon electronic devices is severely degraded by\nthe presence of a parasitic conduction pathway at the nitride-substrate\ninterface which contributes to switching losses and lower breakdown voltages.\nThe physical nature of such a parasitic channel and its properties are however,\nnot well understood. We report on a pronounced thickness dependence of the\nparasitic channel formation at AlN/Si interfaces due to increased surface\nacceptor densities at the interface in silicon. The origin of these surface\nacceptors is analyzed using secondary ion mass spectroscopy measurements and\ntraced to thermal acceptor formation due to Si-O-N complexes. Low-temperature\n(5K) magneto-resistance (MR) data reveals a transition from positive to\nnegative MR with increasing AlN film thickness indicating the presence of an\ninversion layer of electrons which also contributes to parasitic channel\nformation but whose contribution is secondary at room temperatures.",
        "positive": "Assessing density functionals using many body theory for hybrid\n  perovskites: Which density functional is the \"best\" for structure simulations of a\nparticular material? A concise, first principles, approach to answer this\nquestion is presented. The random phase approximation (RPA)--- an accurate many\nbody theory--- is used to evaluate various density functionals. To demonstrate\nand verify the method, we apply it to the hybrid perovskite MAPbI$_3$, a\npromising new solar cell material. The evaluation is done by first creating\nfinite temperature ensembles for small supercells using RPA molecular dynamics,\nand then evaluating the variance between the RPA and various approximate\ndensity functionals for these ensembles. We find that, contrary to recent\nsuggestions, van der Waals functionals do not improve the description of the\nmaterial, whereas hybrid functionals and the SCAN (strongly constrained\nappropriately normed) density functional yield very good agreement with the\nRPA. Finally, our study shows that in the room temperature tetragonal phase of\nMAPbI$_3$, the molecules are preferentially parallel to the shorter lattice\nvectors but reorientation on ps timescales is still possible."
    },
    {
        "anchor": "Unexpected Xe cations and superconductivity in Y-Xe compounds under\n  pressure: The metal-based noble gas compounds exhibit interesting behavior of\nelectronic valence states under pressure. For example, Xe upon compression can\ngain electrons from the alkali metal, or lose electrons unexpectedly to Fe and\nNi, toward formation of stable metal compounds. In addition, the Na2He is not\neven stabilized by the local chemical bonds but via the long-range Coulomb\ninteractions. Herein, by using the first-principles calculations and the\nunbiased structure searching techniques, we uncover that the transition metal Y\nis able to react with Xe above 60 GPa within various Y-Xe stochiometries,\nnamely the YXe, YXe2, YXe3 and Y3Xe structures. Surprisingly, it is found that\nall the resulting compounds are intermetallic and Xe atoms are positively\ncharged. We also argue that the pressure-induced changes of the energy orbital\nfilling are responsible for the electron transfer from Xe to Y. Meanwhile, the\nPeierls-like mechanism is found to stabilize the energetically most favorable\nYXe-Pbam phase. Furthermore, the predicted YXe-Pbam, YXe-Pnnm, and YXe3-I4/mcm\nphases are discovered to be phonon-mediated superconductors under pressure,\nwith the critical superconducting temperatures in the range of approximately\n3-4K, 7-10K, and 5-6K, respectively. In summary, our work promotes further\nunderstanding of the crystal structures and electronic properties of the\nmetal-based noble gas compounds.",
        "positive": "Surface Core Level Shifts of Clean and Oxygen Covered Ru(0001): We have performed high resolution XPS experiments of the Ru(0001) surface,\nboth clean and covered with well-defined amounts of oxygen up to 1 ML coverage.\nFor the clean surface we detected two distinct components in the Ru 3d_{5/2}\ncore level spectra, for which a definite assignment was made using the high\nresolution Angle-Scan Photoelectron Diffraction approach. For the p(2x2),\np(2x1), (2x2)-3O and (1x1)-O oxygen structures we found Ru 3d_{5/2} core level\npeaks which are shifted up to 1 eV to higher binding energies. Very good\nagreement with density functional theory calculations of these Surface Core\nLevel Shifts (SCLS) is reported. The overriding parameter for the resulting Ru\nSCLSs turns out to be the number of directly coordinated O atoms. Since the\ncalculations permit the separation of initial and final state effects, our\nresults give valuable information for the understanding of bonding and\nscreening at the surface, otherwise not accessible in the measurement of the\ncore level energies alone."
    },
    {
        "anchor": "Ballistic vs Diffusive Transport in Current-Induced Magnetization\n  Switching: We test whether current-induced magnetization switching due to\nspin-transfer-torque in ferromagnetic/non-magnetic/ferromagnetic (F/N/F)\ntrilayers changes significantly when scattering within the N-metal layers is\nchanged from ballistic to diffusive. Here ballistic corresponds to a ratio r =\nlambda/t greater than or equal to 3 for a Cu spacer layer, and diffusive to r =\nlambda/t less than or equal to 0.4 for a CuGe alloy spacer layer, where lambda\nis the mean-free-path in the N-layer of fixed thickness t = 10 nm. The average\nswitching currents for the alloy spacer layer are only modestly larger than\nthose for Cu. The best available model predicts a much greater sensitivity of\nthe switching currents to diffuse scattering in the spacer layer than we see.",
        "positive": "Environmental Effects in Mechanical Properties of Few-layer Black\n  Phosphorus: We report on the mechanical properties of few-layer black phosphorus (BP)\nnanosheets, in high vacuum and as a function of time of exposure to atmospheric\nconditions [1]. BP flakes with thicknesses ranging from 4 to 30 nm suspended\nover circular holes are characterized by nanoindentations using an atomic force\nmicroscope tip. From measurements in high vacuum an elastic modulus of 46+/-10\nGPa and breaking strength of 2.4+/-1 GPa are estimated. Both magnitudes are\nindependent of the thickness of the flakes. Our results show that the exposure\nto air has substantial influence in the mechanical response of flakes thinner\nthan 6 nm but small effects on thicker flakes."
    },
    {
        "anchor": "Structure, Stability and Mechanical Properties of Boron-Rich Mo-B\n  Phases: A Computational Study: Molybdenum borides were studied theoretically using first-principles\ncalculations, empirical total energy model and global optimization techniques\nto determine stable crystal structures. Our calculations reveal the structures\nof known Mo-B phases, attaining close agreement with experiment. Following our\ndeveloped lattice model, we describe in detail the crystal structure of\nboron-rich $MoB_x$ phases with 3<x<9 as the hexagonal $P6_3/mmc$-$MoB_3$\nstructure with Mo atoms partially replaced by triangular boron units. The most\nenergetically stable arrangement of these $B_3$ units corresponds to their\nuniform distribution in the bulk of the crystal structure, which leads to the\nformation of a disordered nonstoichiometric phase, with ordering arising at\ncompositions close to x=5 due to a strong repulsive interaction between\nneighboring $B_3$ units. The most energetically favorable structures of $MoB_x$\ncorrespond to the compositions 4<x<5, with $MoB_5$ being the boron-richest\nstable phase. The estimated hardness of $MoB_5$ is 37-39 GPa, suggesting that\nthe boron-rich phases are potentially superhard.",
        "positive": "Temperature-dependent mechanical properties of ZrC and HfC from first\n  principles: In order to gain insight into the effect of elevated temperature on\nmechanical performance of ZrC and HfC, the temperature-dependent elastic\nconstants of these two carbides have been systematically studied using two\ndifferent methods (first-principles qusi-harmonic approximation and\nfirst-principles qusi-static approximation). Isoentropic C$_{11}$ gradually\ndecrease and the isoentropic C$_{12}$ slightly increases for ZrC and HfC under\ntemperature. While the isoentropic C$_{44}$ of both ZrC and HfC is insensitive\nto the temperature. In both ZrC and HfC cases, the decline of\ntemperature-dependent C$_{11}$ calculated from QHA is more pronounced than from\nQSA. Temperature effects on modulus of elasticity, poisson's ratio, elastic\nanisotropy, hardness and fracture toughness are further explored and discussed.\nThe results indicate that degradation of B, G and E estimated from QHA is more\nserious than these from QSA at high temperature. From room temperature to 2500\nK, the theoretical decreasing slope (from QHA) of B, G, and E is 0.38\nGPa$\\cdot$K$^{-1}$, 0.30 GPa$\\cdot$K$^{-1}$, and 0.32 GPa$\\cdot$K$^{-1}$ for\nZrC and 0.33 GPa$\\cdot$K$^{-1}$, 0.29 GPa$\\cdot$K$^{-1}$, and 0.30\nGPa$\\cdot$K$^{-1}$ for HfC."
    },
    {
        "anchor": "Small polaron formation in dangling-bond wires on the Si(001) surface: From electronic structure calculations, we find that carriers injected into\ndangling-bond atomic wires on the Si(001) surface will self-trap to form\nlocalised polaron states. The self-trapping distortion takes the form of a\nlocal suppression of the buckling of the dimers in the wire, and is\nqualitatively different for the electron and hole polarons. This result points\nto the importance of polaronic effects in understanding electronic motion in\nsuch nanostructures.",
        "positive": "From first- to second-order phase transitions in hybrid improper\n  ferroelectrics through entropy stabilisation: Hybrid improper ferroelectrics (HIFs) have been intensely studied over the\nlast few years to gain understanding of their temperature induced phase\ntransitions and ferroelectric switching pathways. Here we report a switching\nfrom first- to second-order phase transition pathway for topical HIFs\n$Ca_{3-x}Sr_xTi_2O_7$, which is driven by the differing entropies of the phases\nthat we identify as being associated with the dynamic motion of octahedral\ntilts and rotations. A greater understanding of the transition pathways in this\nclass of layered perovskites, which host many physical properties that are\ncoupled to specific symmetries and octahedral rotation and tilt distortions --\nsuch as superconductivity, negative thermal expansion, fast ion conductivity,\nferroelectricity, among others -- is a crucial step in creating novel\nfunctional materials by design."
    },
    {
        "anchor": "Tip-Induced $\u03b2$-Hydrogen Dissociation in an Alkyl Group Bound on\n  Si(001): Atomic-scale chemical modification of surface-adsorbed ethyl groups on\nSi(001) was induced and studied by means of scanning tunneling microscopy.\nTunneling at sample bias > +1.5V leads to tip-induced C-H cleavage of a\n$\\beta$-hydrogen of the covalently bound ethyl configuration. The reaction is\ncharacterized by the formation of an additional Si-H and a Si-C bond. The\nreaction probability shows a linear dependence on the tunneling current at 300\nK; the reaction is largely suppressed at 50 K. The observed tip-induced surface\nreaction at room temperature is thus attributed to a one-electron excitation in\ncombination with thermal activation.",
        "positive": "Effect of doping and In-composition on gain of long wavelength\n  III-nitride QDs: In this work, we calculate material gain for long wavelength III-nitride InN\nand AlInN quantum dot (QD) structures. Strain and QD inhomogeneity are included\nin the calculations. The study covers (800-2300 nm) wavelength range which is\nimportant in optical communications. While p-doping is shown to be efficient to\nincreasing gain, changing QD size (especially QD radius) is more efficient to\nvary wavelength. The results predicted that n-doped QD structures are promises\nfor broad band laser applications."
    },
    {
        "anchor": "Novel temperature operated electrooptical materials based on K2ZnCl4:\n  PVA polymer nanocomposites: We have discovered significant temperature anomalies of the linear\nelectrooptical (EOE) coefficients for the K2ZnCl4 nanocrystallites embedded\ninto the polymer matrices. The EOE efficiency was operated by external\ndc-electric field and UV polarized laser light. The maximal enhancement of EOE\noutput was achieved within the temperature range 375 K-420 K. This temperature\nrange corresponds to existence of incommensurate structural modulation. The\nmaximally achieved field induced EOE efficiency was equal to about 1.4 pm/V for\noff-diagonal EOE tensor component. The size and NC content dependences have\nbeen explored for the size range (20 nm-1500 nm) and contents varying within\nthe 25%-35%. For the sizes about 1200 nm, the EOE is commensurable with the EOE\nof the bulk crystals and is equal to about 0.6 pm/V.",
        "positive": "Density-functional investigation of rhombohedral stacks of graphene:\n  topological surface states, nonlinear dielectric response, and bulk limit: A DFT-based investigation of rhombohedral (ABC)-type graphene stacks in\nfinite static electric fields is presented. Electronic band structures and\nfield-induced charge densities are compared with related literature data as\nwell as with own results on (AB) stacks. It is found, that the undoped\nAB-bilayer has a tiny Fermi line consisting of one electron pocket around the\nK-point and one hole pocket on the line K-$\\Gamma$. In contrast to (AB) stacks,\nthe breaking of translational symmetry by the surface of finite (ABC) stacks\nproduces a gap in the bulk-like states for slabs up to a yet unknown critical\nthickness $N^{\\rm semimet} \\gg 10$, while ideal (ABC) bulk ($\\beta$-graphite)\nis a semi-metal. Unlike in (AB) stacks, the ground state of (ABC) stacks is\nshown to be topologically non-trivial in the absence of external electric\nfield. Consequently, surface states crossing the Fermi level must unavoidably\nexist in the case of (ABC)-type stacking, which is not the case in (AB)-type\nstacks. These surface states in conjunction with the mentioned gap in the\nbulk-like states have two major implications. First, electronic transport\nparallel to the slab is confined to a surface region up to the critical layer\nnumber $N^{\\rm semimet}$. Related implications are expected for stacking domain\nwalls and grain boundaries. Second, the electronic properties of (ABC) stacks\nare highly tunable by an external electric field. In particular, the dielectric\nresponse is found to be strongly nonlinear and can e.g. be used to discriminate\nslabs with different layer numbers. Thus, (ABC) stacks rather than (AB) stacks\nwith more than two layers should be of potential interest for applications\nrelying on the tunability by an electric field."
    },
    {
        "anchor": "Spatially dispersive circular photogalvanic effect in a Weyl semimetal: Weyl semimetals are gapless topological states of matter with broken\ninversion and/or time reversal symmetry, which can support unconventional\nresponses to externally applied electrical, optical and magnetic fields. Here\nwe report a new photogalvanic effect in type-II WSMs, MoTe2 and Mo0.9W0.1Te2,\nwhich are observed to support a circulating photocurrent when illuminated by\ncircularly polarized light at normal incidence. This effect occurs exclusively\nin the inversion broken phase, where crucially we find that it is associated\nwith a spatially varying beam profile via a new dispersive contribution to the\ncircular photogalvanic effect (s-CPGE). The response functions derived for\ns-CPGE reveal the microscopic mechanism of this photocurrent, which are\ncontrolled by terms that are allowed in the absence of inversion symmetry,\nalong with asymmetric carrier excitation and relaxation. By evaluating this\nresponse for a minimal model of a Weyl semimetal, we obtain the frequency\ndependent scaling behavior of this form of photocurrent. These results\ndemonstrate opportunities for controlling photoresponse by patterning optical\nfields to store, manipulate and transmit information over a wide spectral\nrange.",
        "positive": "High-pressure synthesis of rock salt LiMeO2-ZnO (Me = Fe3+, Ti3+) solid\n  solutions: Metastable LiMeO2-ZnO (Me = Fe3+, Ti3+) solid solutions with rock salt\ncrystal structure have been synthesized by solid state reaction of ZnO with\nLiMeO2 complex oxides at 7.7 GPa and 1350-1450 K. Structure, phase composition,\nthermal stability and thermal expansion of the recovered samples have been\nstudied by X-ray diffraction with synchrotron radiation. At ambient pressure\nrock salt LiMeO2-ZnO solid solutions are kinetically stable up to 670-800 K\ndepending on the composition."
    },
    {
        "anchor": "Remarkable enhancement in crystalline perfection, Second Harmonic\n  Generation Efficiency, Optical Transparency and laser damage threshold in KDP\n  crystals by L-threonine doping: Effect of L-threonine (LT) doping on crystalline perfection, second harmonic\ngeneration (SHG) efficiency, optical transparency and laser damage threshold\n(LDT) in potassium dihydrogen phosphate (KDP) crystals grown by slow\nevaporation solution technique (SEST) has been investigated. The influence of\ndoping on growth rate and morphology of the grown crystals has also been\nstudied. Powder X-ray diffraction data confirms the crystal structure of KDP\nand shows a systematic variation in intensity of diffraction peaks in\ncorrelation with morphology due to varying LT concentration. No extra phase\nformation was observed which is further confirmed by Fourier Transform (FT)\nRaman studies. High-resolution X-ray diffraction curves indicate that\ncrystalline perfection has been improved to a great extent at low\nconcentrations with a maximum perfection at 1 mol% doping. At higher\nconcentrations (5 to 10 mol%), it is slightly reduced due to excess\nincorporation of dopants at the interstitial sites of the crystalline matrix.\nLDT has been increased considerably with increase in doping concentration,\nwhereas SHG efficiency was found to be maximum at 1 mol% in correlation with\ncrystalline. The optical transparency for doped crystals has been increased as\ncompared to that of pure KDP with a maximum value at 1 mol% doping.",
        "positive": "Beyond double-resonant Raman scattering: UV Raman spectroscopy on\n  graphene, graphite and carbon nanotubes: We present an analysis of deep-UV Raman measurements of graphite, graphene\nand carbon nanotubes. For excitation energies above the strong optical\nabsorption peak at the $M$ point in the Brillouin zone ($\\approx\n4.7\\,\\text{eV}$), we partially suppress double-resonant scattering processes\nand observe the two-phonon density of states of carbon nanomaterials. The\nmeasured peaks are assigned to contributions from LO, TO, and LA phonon\nbranches, supported by calculations of the phonon dispersion. Moreover, we gain\naccess to the infrared-active $E_{1u}$ mode in graphite. By lowering the\nexcitation energy and thus allowing double-resonant scattering processes, we\ndemonstrate the rise of the \\textit{2D} mode in graphite with ultra-short\nphonon wave vectors."
    },
    {
        "anchor": "Observing and modeling the sequential pairwise reactions that drive\n  solid-state ceramic synthesis: Solid-state synthesis from powder precursors is the primary processing route\nto advanced multicomponent ceramic materials. Designing ceramic synthesis\nroutes is usually a laborious, trial-and-error process, as heterogeneous\nmixtures of powder precursors often evolve through a complicated series of\nreaction intermediates. Here, we show that phase evolution from multiple\nprecursors can be modeled as a sequence of pairwise interfacial reactions, with\nthermodynamic driving forces that can be efficiently calculated using ab initio\nmethods. Using the synthesis of the classic high-temperature superconductor\nYBa$_2$Cu$_3$O$_{6+x}$ (YBCO) as a representative system, we rationalize how\nreplacing the common BaCO$_3$ precursor with BaO$_2$ redirects phase evolution\nthrough a kinetically-facile pathway. Our model is validated from in situ X-ray\ndiffraction and in situ microscopy observations, which show rapid YBCO\nformation from BaO$_2$ in only 30 minutes. By combining thermodynamic modeling\nwith in situ characterization, we introduce a new computable framework to\ninterpret and ultimately design synthesis pathways to complex ceramic\nmaterials.",
        "positive": "Anomalous Hall hysteresis in Tm3Fe5O12/Pt with strain-induced\n  perpendicular magnetic anisotropy: We demonstrate robust interface strain-induced perpendicular magnetic\nanisotropy in atomically flat ferrimagnetic insulator Tm3Fe5O12 films grown\nwith pulsed laser deposition on substituted-Gd3Ga5O12 substrate which maximizes\nthe tensile strain at the interface. In bilayers consisting of Pt and TIG, we\nobserve large squared Hall hysteresis loops over a wide range of thicknesses of\nPt at room temperature. When a thin Cu layer is inserted between Pt and TIG,\nthe Hall hysteresis magnitude decays but stays finite as the thickness of Cu\nincreases up to 5 nm. However, if the Cu layer is placed atop Pt instead, the\nHall hysteresis magnitude is consistently larger than when the Cu layer with\nthe same thickness is inserted in between for all Cu thicknesses. These results\nsuggest that both the proximity-induced ferromagnetism and spin current\ncontribute to the anomalous Hall effect."
    },
    {
        "anchor": "Direct Measure of Giant Magnetocaloric Entropy Contributions in Ni-Mn-In: Off-stoichiometric alloys based on Ni 2 MnIn have drawn attention due to the\ncoupled first order magnetic and structural transformations, and the large\nmagnetocaloric entropy associated with the transformations. Here we describe\ncalorimetric and magnetic studies of four compositions. The results provide a\ndirect measure of entropy changes contributions including at the first-order\nphase transitions, and thereby a determination of the maximum field-induced\nentropy change corresponding to the giant magnetocaloric effect. We find a\nlarge excess entropy change, attributed to magneto-elastic coupling, but only\nin compositions with no ferromagnetic order in the high-temperature austenite\nphase. Furthermore, a molecular field model corresponding to antiferromagnetism\nof the low-temperature phases is in good agreement, and nearly independent of\ncomposition, despite significant differences in overall magnetic response of\nthese materials.",
        "positive": "Controlling adsorbate vibrational lifetimes using superlattices: We propose using short-period superlattices as substrates to control the\nvibrational relaxation dynamics of adsorbate overlayers. The mass modulation of\nsuperlattices creates both band gaps and large spectral enhancements in the\nphonon density of states. These modifications can dramatically alter the\ncoupling between vibrational modes of the adsorbate overlayer and the substrate\nlattice, thereby significantly affecting the lifetime of adsorbate modes."
    },
    {
        "anchor": "Nucleation and step-edge barriers always destabilize step-flow growth of\n  a vicinal surface: We consider the effect of nucleation on a one-dimensional stepped surface,\nfinding that step-flow growth is metastable for any strength of the additional\nstep-edge barrier. The surface is made unstable by the formation of a critical\nnucleus, whose lateral size is related to the destabilization process on a\nhigh-symmetry surface. Arguments based on a critical nucleus of height two,\nwhich suggest the existence of a fully stable regime for small barrier, fail to\ndescribe this phenomenon.",
        "positive": "An Interpretable Boosting-based Predictive Model for Transformation\n  Temperatures of Shape Memory Alloys: In this study, we demonstrate how the incorporation of appropriate feature\nengineering together with the selection of a Machine Learning (ML) algorithm\nthat best suits the available dataset, leads to the development of a predictive\nmodel for transformation temperatures that can be applied to a wide range of\nshape memory alloys. We develop a gradient boosting ML surrogate model capable\nof predicting Martensite Start, Martensite Finish, Austenite Start, and\nAustenite Finish transformation temperatures with an average accuracy of more\nthan 95% by explicitly taking care of potential distribution changes when\nmodeling different alloy systems. We included heat treatment, rolling,\nextrusion processing parameters, and alloy system categorical features in the\nmodel input features to achieve more accurate and realistic results. In\naddition, using Shapley values, which are calculated based on the average\nmarginal contribution of features to all possible coalitions, this study was\nable to gain insights into the governing features and their effect on predicted\ntransformation temperatures, providing a unique opportunity to examine the\ncritical parameters and features in martensite transformation temperatures."
    },
    {
        "anchor": "Electronic and Structural Properties of Janus SMoSe/MoX$_2$ (X=S,Se)\n  In-plane Heterojunctions: A DFT Study: The electronic and structural properties of Janus MoSSe/MoX$_2$ (X=S,Se)\nin-plane heterojunctions, endowed with single-atom vacancies, were studied\nusing density functional theory calculations. The stability of these structures\nwas verified from cohesion energy calculations. Results showed that single-atom\nvacancies induce the appearance of flat midgap states, and a substantial amount\nof charge is localized in the vicinity of these defects. As a consequence,\nthese heterojunctions presented an intrinsic dipole moment. No bond\nreconstructions were noted by removing an atom from the lattice, regardless of\nits chemical species. Our calculations predicted indirect electronic bandgap\nvalues between 1.6-1.7 eV.",
        "positive": "On the fundamental aspect of the first Kelvin's relation in\n  thermoelectricity: Kelvin's relations may be considered as cornerstones in the theory of\nthermoelectricity. Indeed, they gather together the three thermoelectric\neffects, associated respectively with Seebeck, Peltier and Thomson, to get a\nunique and consistent description of thermoelectric phenomena. However, their\nphysical status in literature are quite different. On the one hand, the second\nKelvin's relation is associated with the microscopic reversibility, considered\nas a fundamental thermodynamical property. On the other hand, the first\nKelvin's relation is traditionally introduced only as a convenient mathematical\nrelation between Seebeck and Thomson coefficients. In the present article, we\nstress that, contrary to common believes, this relation may demonstrates deeper\ninsights than a bold mathematical expression between thermoelectric\ncoefficients. It actually reflects the coexistence of two different mechanisms\ntaking place inside thermoelectric systems: Energy conversion and\nreorganization of heat flow when Seebeck coefficient varies."
    },
    {
        "anchor": "Many-body effects on the quasiparticle band structure and optical\n  response of single-layer penta-NiN$_2$: We present a comprehensive first-principles study on the optoelectronic\nproperties of the single-layer nickel diazenide (penta-NiN$_2$), a recently\nsynthesized Cairo pentagonal 2D semiconductor. We carry out $ab$ $initio$\ncalculations based on the density-functional theory (DFT) and many-body\nperturbation theory, within the framework of Green's functions, to describe the\nquasiparticle properties and analyze the excitonic effects on the optical\nproperties of monolayer penta-NiN$_2$. Our results reveal a quasiparticle band\ngap of approximately 1 eV within the eigenvalue self-consistent $GW$ approach,\ncorroborating the monolayer penta-NiN$_2$'s potential in optoelectronics.\nRemarkably, the acoustic phonon-limited carrier mobility for the monolayer\npenta-NiN$_2$ exhibits an ultra-high hole mobility of $84{\\times}10^4$\ncm$^2$/V$\\cdot$s. Furthermore, our findings indicate that the material's band\ngap exhibits an anomalous negative dependence on temperature. Despite being a\ntwo-dimensional material, monolayer penta-NiN$_2$ presents resonant excitons in\nits most prominent absorption peak. Therefore, penta-NiN$_2$ boasts compelling\nand promising properties that merit exploration in optoelectronics and\nhigh-speed devices.",
        "positive": "Nanomagnetic toggle switching of vortex cores on the picosecond time\n  scale: We present an ultrafast route for a controlled, toggle switching of magnetic\nvortex cores with ultrashort unipolar magnetic field pulses. The switching\nprocess is found to be largely insensitive to extrinsic parameters, like sample\nsize and shape, and it is faster than any field-driven magnetization reversal\nprocess previously known from micromagnetic theory. Micromagnetic simulations\ndemonstrate that the vortex core reversal is mediated by a rapid sequence of\nvortex-antivortex pair-creation and annihilation sub-processes. Specific\ncombinations of field pulse strength and duration are required to obtain a\ncontrolled vortex cores reversal. The operational range of this reversal\nmechanism is summarized in a switching diagram for a 200 nm Permalloy disk."
    },
    {
        "anchor": "Quantum Stress Focusing in Descriptive Chemistry: We show that several important concepts of descriptive chemistry, such as\natomic shells, bonding electron pairs and lone electron pairs, may be described\nin terms of {\\it quantum stress focusing}, i.e. the spontaneous formation of\nhigh-pressure regions in an electron gas. This description subsumes previous\nmathematical constructions, such as the Laplacian of the density and the\nelectron localization function, and provides a new tool for visualizing\nchemical structure. We also show that the full stress tensor, defined as the\nderivative of the energy with respect to a local deformation, can be easily\ncalculated from density functional theory.",
        "positive": "Rietveld refinement of ZrSiO4: application of a phenomenological model\n  of anisotropic peak width: The anisotropic broadening of ZrSiO4 sample is modelled using the Stephens's\nphenomenological model for anisotropic line broadening and the three\ndimensional strain distribution in the sample is plotted. The micro-structural\nparameters like domain size and dislocation density are estimated using the\nvariance method."
    },
    {
        "anchor": "On the interpretation of valence band photoemission spectra at\n  organic-metal interfaces: Adsorption of organic molecules on well-oriented single crystal coinage metal\nsurfaces fundamentally affects the energy distribution curve of ultra-violet\nphotoelectron spectroscopy spectra. New features not present in the spectrum of\nthe pristine metal can be assigned as \"interface states\" having some degree of\nmolecule-substrate hybridization. Here it is shown that interface states having\nmolecular orbital character can easily be identified at low binding energy as\nisolated features above the featureless substrate sp-plateau. On the other hand\nmuch care must be taken in assigning adsorbate-induced features when these lie\nwithin the d-band spectral region of the substrate. In fact, features often\ninterpreted as characteristic of the molecule-substrate interaction may\nactually arise from substrate photoelectrons scattered by the adsorbates. This\nphenomenon is illustrated through a series of examples of noble-metal\nsingle-crystal surfaces covered by monolayers of large pi-conjugated organic\nmolecules.",
        "positive": "Origin of traps and charge transport mechanism in hafnia: In this study, we demonstrated experimentally and theoretically that oxygen\nvacancies are responsible for the charge transport in HfO$_2$. Basing on the\nmodel of phonon-assisted tunneling between traps, and assuming that the\nelectron traps are oxygen vacancies, good quantitative agreement between the\nexperimental and theoretical data of current-voltage characteristics were\nachieved. The thermal trap energy of 1.25 eV in HfO$_2$ was determined based on\nthe charge transport experiments."
    },
    {
        "anchor": "Topological Dirac Nodal Lines and Surface Charges in fcc Alkaline Earth\n  Metals: In nodal-line semimetals, the gaps close along loops in ${\\bf k}$ space,\nwhich are not at high-symmetry points. Typical mechanisms for the emergence of\nnodal lines involve mirror symmetry and the $\\pi$ Berry phase. Here, we show\nvia ab initio calculations that fcc calcium (Ca), strontium (Sr) and ytterbium\n(Yb) have topological nodal lines with the $\\pi$ Berry phase near the Fermi\nlevel, when spin-orbit interaction is neglected. In particular, Ca becomes a\nnodal-line semimetal at high pressure. Owing to nodal lines, the Zak phase\nbecomes either $\\pi$ or 0 depending on the wavavector ${\\bf k}$, and the $\\pi$\nZak phase leads to surface polarization charge. Carriers eventually screen it,\nleaving behind large surface dipoles. In materials with nodal lines, both the\nlarge surface polarization charge and the emergent drumhead surface states\nenhance Rashba splitting when heavy adatoms are present, as we have shown to\noccur in Bi/Sr(111) and in Bi/Ag(111).",
        "positive": "Evidence for the intrinsic ferromagnetism of semiconductor (Ga,Cr)As\n  revealed by magnetic circular dichroism: To clarify whether or not (Ga,Cr)As is an intrinsic diluted magnetic\nsemiconductor, a systematic study of the magnetic circular dichroism (MCD) was\ncarried out for a series of (Ga,Cr)As epilayers grown by the low-temperature\nmolecular-beam epitaxy technique. The present work provides unambiguous\nevidence for the intrinsic ferromagnetism of the (Ga,Cr)As epilayers with all\nthe necessary properties in accordance with that of a diluted magnetic\nsemiconductor, especially the hysteresis characteristics, which is opened up in\nthe magnetic field dependence of MCD."
    },
    {
        "anchor": "Growth and characterization of insulating ferromagnetic semiconductor\n  (Al,Fe)Sb: We investigate the crystal structure, transport and magnetic properties of\nFe-doped ferromagnetic semiconductor (Al1-x,Fex)Sb thin films up to x = 14%\ngrown by molecular beam epitaxy. All the samples show p-type conduction at room\ntemperature and insulating behavior at low temperature. The (Al1-x,Fex)Sb thin\nfilms with x lower or equal to 10% maintain the zinc blende crystal structure\nof the host material AlSb. The (Al1-x,Fex)Sb thin film with x = 10% shows\nintrinsic ferromagnetism with a Curie temperature (TC) of 40 K. In the\n(Al1-x,Fex)Sb thin film with x = 14%, a sudden drop of mobility and TC was\nobserved, which may be due to microscopic phase separation. The observation of\nferromagnetism in (Al,Fe)Sb paves the way to realize a spin-filtering tunnel\nbarrier that is compatible with well-established III-V semiconductor devices.",
        "positive": "Graphene-like Dirac states and Quantum Spin Hall Insulators in the\n  square-octagonal MX2 (M=Mo, W; X=S, Se, Te) Isomers: We studied the square-octagonal lattice of the transition metal\ndichalcogenide MX$_2$ (with $M$=Mo, W; $X$=S, Se and Te), as an isomer of the\nnormal hexagonal compound of MX$_2$. By band structure calculations, we observe\nthe graphene-like Dirac band structure in a rectangular lattice of MX$_2$ with\nnonsymmorphic space group symmetry. Two bands with van Hove singularity points\ncross each at the Fermi energy, leading to two Dirac cones that locates at\nopposite momenta. Spin-orbit coupling can open a nontrivial gap at these Dirac\npoints and induce the quantum spin Hall (QSH) phase, the 2D topological\ninsulator. Here, square-octagonal MX$_2$ structures realize the interesting\ngraphene physics, such as Dirac bands and QSH effect, in the transition metal\ndichalcogenides."
    },
    {
        "anchor": "Introduction to the theory of left-handed media: This paper is devoted to investigating the physically interesting optical and\nelectromagnetic properties, phenomena and effects of wave propagation in the\nnegative refractive index materials, which is often referred to as the {\\it\nleft-handed media} in the literature. This paper covers a wide range of\nsubjects and related topics of left-handed media such as many mathematical\ntreatment of fundamental effects ({\\it e.g.}, the reflection and the refraction\nlaws on the interface between LH and RH media, the group velocity and energy\ndensity in dispersive materials, the negative optical refractive index\nresulting from a moving regular medium, the reversal of Doppler effect in\nleft-handed media, the reversal of Cerenkov radiation in left-handed media, the\noptical refractive index of massive particles and physical meanings of\nleft-handed media, the anti-shielding effect and negative temperature in\nleft-handed media, {\\it etc.}), and their some applications to certain areas\n({\\it e.g.}, three kinds of compact thin subwavelength cavity resonators\n(rectangular, cylindrical, spherical) made of left-handed media, the photon\ngeometric phases due to helicity inversions inside a periodical fiber made of\nleft-handed media, {\\it etc.}).",
        "positive": "Magnetic and structural studies of G-phase compound\n  Mn$_6$Ni$_{16}$Si$_7$: Transition metal compounds with complex crystal structures tend to\ndemonstrate interesting magnetic coupling resulting in unusual magnetic\nproperties. In this work, the structural and magnetic characterization of a\nsingle crystal of the Ni-Mn-Si based G-phase compound, Mn$_6$Ni$_{16}$Si$_7$,\ngrown by the Czochralski method, is reported. In this structure isolated\noctahedral Mn$_6$ clusters form a f.c.c. lattice. As each octahedron consists\nof eight edge-sharing equilateral triangles, the possibility for geometric\nfrustration exists. Magnetization and specific heat measurements showed two\nmagnetic phase transitions at 197 K and 50 K, respectively. At 100 K neutron\ndiffraction on powder samples shows a magnetic structure with k = (001) in\nwhich only four of the six Mn spins per cluster order along $<100>$ directions\ngiving a two dimensional magnetic structure consistent with intra-cluster\nfrustration. Below the 50 K phase transition the Mn spins cant away from\n$<100>$ directions and a weak moment develops on the two remaining Mn\noctahedral sites."
    },
    {
        "anchor": "Mechanisms of GaN quantum dot formation during nitridation of Ga\n  droplets: We have examined the formation mechanisms of GaN quantum dots (QDs) via\nannealing of Ga droplets in a nitrogen flux. We consider the temperature and\nsubstrate dependence of the size distributions of droplets and QDs, as well as\nthe relative roles of Ga/N diffusivity and GaN nucleation rates on QD\nformation. We report on two competing mechanisms mediated by Ga surface\ndiffusion, namely QD formation at or away from pre-existing Ga droplets. We\ndiscuss the relative roles of nucleation and coarsening dominant growth, as\nwell as the polytype selection, on various substrates. The new insights provide\nan opportunity for tailoring QD size and polytype distributions for a wide\nrange of III-N semiconductor QDs.",
        "positive": "Microwave magnetic dynamics in ferromagnetic metallic nanostructures\n  lacking inversion symmetry: In this work we carried out systematic experimental and theoretical\ninvestigations of the ferromagnetic (FMR) response of quasi-two-dimensional\nmagnetic nano-objects - microscopically long nanostripes made of ferromagentic\nmetals. We were interested in the impact of the symmetries of this geometry on\nthe FMR response. Three possible scenarios, from which the inversion symmetry\nbreak originated, were investigated:(1) from the shape of the stripe\ncross-section, (2) from the double-layer structure of the stripes with exchange\ncoupling between the layers, and (3) from the single-side incidence of the\nmicrowave magnetic field on the plane of the nano-pattern. The latter scenario\nis characteristic of the stripline FMR configuration. It was found that the\ncombined effect of the three symmetry breaks is much stronger than the impacts\nof each of these symmetry breaks separately."
    },
    {
        "anchor": "On the Variability of Grain Boundary Mobility in the Isoconfigurational\n  Ensemble: Recent grain growth experiments have revealed that the same type of grain\nboundary can have very different mobilities depending on its local\nmicrostructure. In this work, we use molecular dynamics simulations to quantify\nuncertainty in the reduced mobility of curved grain boundaries for different\ntypes of boundary conditions and over a range of initial velocity seeds. We\nconsider cylindrical island grains in Ni with a [001] tilt axis as a model\nsystem. Unexpectedly, we find large variation in the reduced mobility of curved\ngrain boundaries depending on both the imposed constraints and the initial\nvelocity distribution. We perform a dynamic propensity analysis inspired from\nstudies of glass forming liquids to analyze sources of variation in reduced\nmobility. Our work highlights the significant impact of initial velocity\ndistributions on grain boundary motion which has not been analyzed in prior\nwork.",
        "positive": "Lattice dynamics effects on finite-temperature stability of\n  $R_{1-x}$Fe$_{x}$ ($R$ = Y, Ce, Nd, Sm, and Dy) alloys from first principles: We report the effects of lattice dynamics on thermodynamic stability of\nbinary $R_{1-x}$Fe$_x$ $(0<x<1)$ compounds ($R$: rare-earth elements, Y, Ce,\nNd, Sm, and Dy) at finite temperature predicted by first-principles calculation\nbased on density functional theory (DFT). We first demonstrate that the\nthermodynamic stability of $R_{1-x}$Fe$_x$ $(0<x<1)$ alloys cannot be predicted\naccurately by the conventional approach, where only the static DFT energy at $T\n= 0$ K is used. This issue can be overcome by considering the entropy\ncontribution, including electronic and vibrational free energies, and we\nobtained convex hull plots at finite temperatures that successfully explain the\nthermodynamic stability of various known compounds. Our systematic calculation\nindicates that vibrational entropy helps stabilize various $R_{1-x}$Fe$_x$\ncompounds with increasing temperature. In particular, experimentally reported\n$R_2$Fe$_{17}$ compounds are predicted to become thermodynamically stable above\n$\\sim$800 K. We also show that thermodynamic stability is rare-earth dependent\nand discuss its origin. Besides the experimentally reported structures, the\nstability of two new monoclinic $R$Fe$_{12}$ structures found by Ishikawa\n\\textit{et al.} [Phys. Rev. Mater.~\\textbf{4}, 104408 (2020)] based on a\ngenetic algorithm are investigated. These monoclinic phases are found to be\ndynamically stable and have larger magnetization than the ThMn$_{12}$-type\n$R$Fe$_{12}$. Although they are thermodynamically unstable, the formation\nenergies decrease significantly with increasing temperature, indicating the\npossibility of synthesizing these compounds at high temperatures."
    },
    {
        "anchor": "Mechanical Characterization of Superelastic NiTi Nanofoams by Molecular\n  Dynamics Simulations: Nanoporous metals or nanofoams are a promising material class that is\nconsidered for sensing, actuation, and catalysis. To date, they mostly based on\nsimple noble metals such as nanoporous gold, which exhibit peculiar\nstress-strain response different from the bulk material. At the same time bulk\nalloys such as NiTi feature a reversible martensitic phase transition giving\nrise to interesting shape memory and superelastic effects. Combining the rich\nmechanics of NiTi with the geometrical features of a nanofoam is expected to\nimprove the mechanical performance of this material. In this atomistic study we\nexplore the behavior of a NiTi nanofoam at varying temperature and its reaction\nto (cyclic) compression. Using molecular dynamics simulations we track the\nmicroscopic processes enabling reversible deformation as well as the mechanical\nfailure mechanisms of the NiTi nanofoam.",
        "positive": "Evolution of ordered nanoporous phases during h-BN growth: Controlling\n  the route from gas-phase precursor to 2D material by $\\textit{in-situ}$\n  monitoring: Large-area single-crystal monolayers of two-dimensional (2D) materials such\nas graphene and hexagonal boron nitride (h-BN) can be grown by chemical vapour\ndeposition (CVD). However, the high temperatures and fast timescales at which\nthe conversion from a gas-phase precursor to the 2D material appear, make it\nextremely challenging to simultaneously follow the atomic arrangements. We\nutilise helium atom scattering to discover and control the growth of novel 2D\nh-BN nanoporous phases during the CVD process. We find that prior to the\nformation of h-BN from the gas-phase precursor, a metastable $(3\\times3)$\nstructure is formed, and that excess deposition on the resulting 2D h-BN leads\nto the emergence of a $(3\\times4)$ structure. We illustrate that these\nnanoporous structures are produced by partial dehydrogenation and\npolymerisation of the borazine precursor upon adsorption. These steps are\nlargely unexplored during the synthesis of 2D materials and we unveil the rich\nphases during CVD growth. Our results provide significant foundations for 2D\nmaterials engineering in CVD, by adjusting or carefully controlling the growth\nconditions and thus exploiting these intermediate structures for the synthesis\nof covalent self-assembled 2D networks."
    },
    {
        "anchor": "Towards chemically neutral carbon cleaning processes: Plasma cleaning of\n  Ni, Rh, and Al reflective optical coatings and thin Al filters for Free\n  Electron Lasers and synchrotron beamline applications: The choice of a reflective optical coating or filter material has to be\nadapted to the intended field of application. This is mainly determined by the\nrequired photon energy range or by the required reflection angle. Among various\nmaterials, nickel and rhodium are standard materials used as reflective\ncoatings for synchrotron mirrors. Conversely, Aluminum is one of the most\ncommonly used materials for extreme ultraviolet (EUV) and soft X-ray filters.\nHowever, both of these types of optics are subject to carbon contamination,\nbeing increasingly problematic for the operation of the high-performance free\nelectron laser (FEL) and synchrotron beamlines. For this reason, an inductively\ncoupled plasma (ICP) source has been used in conjunction with N2/O2/H2 and\nN2/H2 feedstock gas plasmas. Results from the chemical surface analysis of the\nabove materials before and after plasma treatment using X-ray photoelectron\nspectroscopy (XPS) are reported. We conclude that a favorable combination of an\nN2/H2 plasma feedstock gas mixture leads to the best chemical surface\npreservation of Ni, Rh, and Al while removing the carbon contaminations.\nHowever, this feedstock gas mixture does not remove C contaminations as rapidly\nas, e.g., a N2/O2/H2 plasma which induces the surface formation of NiO and\nNiOOH in Ni and RhOOH in Rh foils. As an applied case, we demonstrate the\nsuccessful carbon removal from ultrathin Al filters previously used at the\nFERMI FEL1 using a N2/H2 plasma.",
        "positive": "A Microscopy Approach to Investigating the Energetics of Small Supported\n  Metal Clusters: Metal clusters are partway between molecular and bulk systems and thus\nexhibit special physical and chemical properties. Atoms can rearrange within a\ncluster to form different structural isomers. Internal degrees of freedom and\nthe interaction with the support - which both are dependent on cluster size -\ncan promote diffusion across a support. Here, we show how fast scanning\ntunneling microscopy (FastSTM) can be used to investigate such dynamical\nbehavior of individual clusters on the example of Pdn (1<=n<=19) on a hexagonal\nboron nitride nanomesh on Rh(111), in particular pertaining to minority species\nand rare events. By tuning the cluster size and varying the temperature to\nmatch the dynamics to the FastSTM frame rate, we followed steady state\ndiffusion of clusters and atoms inside the nanomesh pore and reversible cluster\nisomerization in situ. While atoms diffuse along the rim of a pore, a small\ncluster experiences a corrugation in the potential energy landscape and jumps\nbetween six sites around the center of the pore. The atom and cluster diffusion\nbetween pores is strongly influenced by defects."
    },
    {
        "anchor": "Electronic, magnetic properties and correlation effects in the layered\n  quaternary iron oxyselenide Na2Fe2Se2O from first principles: By means of the first-principle calculations, we have investigated\nelectronic, magnetic properties and correlation effects for the newly\ndiscovered layered oxyselenide Na2Fe2Se2O. Our results reveal that the electron\ncorrelations in the Fe 3d bands promote a transition of Na2Fe2Se2O from\nmagnetic metallic or half-metallic states to the antiferromagnetic\nMott-insulating state. In addition, the bonding picture in Na2Fe2Se2O is\ndescribed as an anisotropic mixture of ionic and covalent contributions.",
        "positive": "Influence of surface passivation on ultrafast carrier dynamics and\n  terahertz radiation generation in GaAs: The carrier dynamics of photoexcited electrons in the vicinity of the surface\nof (NH4)2S-passivated GaAs were studied via terahertz (THz) emission\nspectroscopy and optical-pump THz-probe spectroscopy. THz emission spectroscopy\nmeasurements, coupled with Monte Carlo simulations of THz emission, revealed\nthat the surface electric field of GaAs reverses after passivation. The\nconductivity of photoexcited electrons was determined via optical-pump\nTHz-probe spectroscopy, and was found to double after passivation. These\nexperiments demonstrate that passivation significantly reduces the surface\nstate density and surface recombination velocity of GaAs. Finally, we have\ndemonstrated that passivation leads to an enhancement in the power radiated by\nphotoconductive switch THz emitters, thereby showing the important influence of\nsurface chemistry on the performance of ultrafast THz photonic devices."
    },
    {
        "anchor": "Observation of inverse magnetocaloric effect in magnetic-field-induced\n  austenite phase of Heusler Alloys Ni50-xCoxMn31.5Ga18.5 (x = 9 and 9.7): Magnetocaloric effect (MCE), magnetization, specific heat, and\nmagnetostriction measurements were performed in both pulsed and steady high\nmagnetic fields to investigate the magnetocaloric properties of Heusler alloys\nNi50-xCoxMn31.5Ga18.5 (x = 9 and 9.7). From direct MCE measurements for\nNi41Co9Mn31.5Ga18.5 up to 56 T, a steep temperature drop was observed for\nmagnetic-field-induced martensitic transformation (MFIMT), designated as\ninverse MCE. Remarkably, this inverse MCE is apparent not only with MFIMT, but\nalso in the magnetic-field-induced austenite phase. Specific heat measurements\nunder steady high magnetic fields revealed that the magnetic field variation of\nthe electronic entropy plays a dominant role in the unconventional\nmagnetocaloric properties of these materials. First-principles based\ncalculations performed for Ni41Co9Mn31.5Ga18.5 and Ni45Co5Mn36.7In13.3 revealed\nthat the magnetic-field-induced austenite phase of Ni41Co9Mn31.5Ga18.5 is more\nunstable than that of Ni45Co5Mn36.7In13.3 and that it is sensitive to slight\ntetragonal distortion. We conclude that the inverse MCE in the\nmagnetic-field-induced austenite phase is realized by marked change in the\nelectronic entropy through tetragonal distortion induced by the externally\napplied magnetic field.",
        "positive": "Perovskite ThTaN3: a Large Thermopower Topological Crystalline Insulator: ThTaN$_3$, a rare cubic perovskite nitride semiconductor, has been studied\nusing {\\it ab initio} methods. Spin-orbit coupling (SOC) results in band\ninversion and a band gap of 150 meV at the zone center. In spite of the trivial\n$Z_2$ indices, two pairs of spin-polarized surface bands cross the gap near the\nzone center, indicating that this system is a topological crystalline insulator\nwith the mirror Chern number of $|{\\cal C}_m|=2$ protected by the mirror and\n$C_4$ rotational symmetries. Additionally, SOC doubles the Seebeck coefficient,\nleading to a maximum of $\\sim$400 $\\mu$V/K at 150 K for carrier-doping levels\nof several $10^{17}$/cm$^3$. ThTaN$_3$ combines excellent bulk thermopower with\nparallel conduction through topological surface states that provide a platform\nfor large engineering devices with ever larger figures of merit."
    },
    {
        "anchor": "Noncollinearity-modulated electronic properties of the monolayer CrI$_3$: Introducing noncollinear magnetization into a monolayer CrI$_3$ is proposed\nto be an effective approach to modulate the local electronic properties of the\ntwo-dimensional (2D) magnetic material. Using first-principles calculation, we\nillustrate that both the conduction and valence bands in the monolayer CrI$_3$\nare lowered down by spin spiral states. The distinct electronic structure of\nthe monolayer noncollinear CrI$_3$ can be applied in nanoscale functional\ndevices. As a proof of concept, we show that a magnetic domain wall can form a\none-dimensional conducting channel in the 2D semiconductor via proper gating.\nOther possible applications such as electron-hole separation and identical\nquantum dots are also discussed.",
        "positive": "Atomic defects and dopants in ternary Z-phase transition-metal nitrides\n  CrMN with M=V, Nb, Ta investigated with density functional theory: A density functional theory study of atomic defects and dopants in ternary\nZ-phase transition-metal nitrides CrMN with M=V, Nb, or Ta is presented.\nVarious defect formation energies of native point defects and of substitutional\natoms of other metal elements which are abundant in the steel as well, are\nevaluated. The dependence thereof on the thermodynamic environment, i.e. the\nchemical conditions of a growing Z-phase precipitate, is studied and different\ngrowth scenarios are compared. The results obtained may help to relate results\nof experimental atomic-scale analysis, by atom probe tomography or transmission\nelectron microscopy, to the theoretical modeling of the formation process of\nthe Z phase from binary transition metal nitrides."
    },
    {
        "anchor": "Engineering the Electronic Structure of Two-Dimensional Materials with\n  Near-Field Electrostatic Effects of Self-Assembled Organic Layers: We compute the electronic structure of two-dimensional (2D) materials\ndecorated with self-assembled organic monolayers using density functional\ntheory. We find that 2D materials are strongly impacted by near-field\nelectrostatic effects resulting from high multipoles of the organic layer\nelectronic density. We show that this effect can lead to significant (~0.5V)\nmodulation of the in-plane potential experienced by electrons in 2D materials\nwithin ~4\\AA from the molecular layer, with a transition between near- and\nfar-field depending on the lateral extent of the molecules. We develop a theory\nof this effect, showing that the electrostatic potential of the molecular layer\ncan be approximated by a discretized planar charge density derived from the\nmolecular structure and multipoles. Solving this model computationally and\nanalytically, we propose implementations of this effect to generate novel\nelectronic properties for electrons in 2D materials, such as band gap opening\nand anisotropic group velocity modulation for monolayer graphene from\nexperimentally achievable molecular assemblies.",
        "positive": "Extracting the intrinsic switching field distribution in perpendicular\n  media: a comparative analysis: We introduce a new method based on the first-order-reversal-curve (FORC)\ndiagram to extract the intrinsic (microscopic) switching-field distribution\n(SFD) of perpendicular recording media (PRM). To demonstrate the viability of\nthe method, we micromagnetically simulated FORCs for PRM with known SFD and\ncompare the extracted SFD with the SFD obtained by means of two different\nmethods that are based on recoil loops, too, which however rely on mean-field\napproximations and assumptions on the shape of the SFD. The FORC method turns\nout to be the most accurate algorithm over a broad range of dipolar interaction\nstrengths, where the other methods overestimate the width of the SFD."
    },
    {
        "anchor": "Molecule signatures in photoluminescence spectra of transition metal\n  dichalcogenides: Monolayer transition metal dichalcogenides (TMDs) show an optimal\nsurface-to-volume ratio and are thus promising candidates for novel molecule\nsensor devices. It was recently predicted that a certain class of molecules\nexhibiting a large dipole moment can be detected through the activation of\noptically inaccessible (dark) excitonic states in absorption spectra of\ntungsten-based TMDs. In this work, we investigate the molecule signatures in\nphotoluminescence spectra in dependence of a number of different experimentally\naccessible quantities, such as excitation density, temperature as well as\nmolecular characteristics including the dipole moment and its orientation,\nmolecule-TMD distance, molecular coverage and distribution. We show that under\ncertain optimal conditions, even room temperature detection of molecules can be\nachieved.",
        "positive": "The Small Unit Cell Reconstructions of SrTiO3 (111): We analyze the basic structural units of simple reconstructions of the (111)\nsurface of SrTiO3 using density functional calculations. The prime focus is to\nanswer three questions: what is the most appropriate functional to use; how\naccurate are the energies; what are the dominant low-energy structures and\nwhere do they lie on the surface phase diagram. Using test calculations of\nrepresentative small molecules we compare conventional GGA with higher-order\nmethods such as the TPSS meta-GGA and on-site hybrid methods PBE0 and TPSSh,\nthe later being the most accurate. There are large effects due to reduction of\nthe metal d oxygen sp hybridization when using the hybrid methods which are\nequivalent to a dynamical GGA+U, which leads to rather substantial improvements\nin the atomization energies of simple calibration molecules, even though the\nd-electron density for titanium compounds is rather small. By comparing the\nerrors of the different methods we are able to generate an estimate of the\ntheoretical error, which is about 0.25eV per 1x1 unit cell, with changes of\n0.5-1.0 eV per 1x1 cell with the more accurate method relative to conventional\nGGA. An analysis of the plausible structures reveals an unusual low-energy\nTiO2-rich configuration with an unexpected distorted trigonal biprismatic\nstructure. This structure can act as a template for layers of either TiO or\nTi2O3, consistent with experimental results as well as, in principle, Magnelli\nphases. The results also suggest that both the fracture surface and the\nstoichiometric SrTiO3 (111) surface should spontaneously disproportionate into\nSrO and TiO2 rich domains, and show that there are still surprises to be found\nfor polar oxide surfaces."
    },
    {
        "anchor": "Magnetic circular dichroism in X-ray fluorescence of Heusler alloys at\n  threshold excitation: The results of fluorescence measurements of magnetic circular dichroism (MCD)\nin Mn L_2,L_3 X-ray emission and absorption for Heusler alloys NiMnSb and\nCo2MnSb are presented. Very intense resonance Mn L_3 emission is found at the\nMn 2p_3/2 threshold and is attributed to a peculiarity of the threshold\nexcitation in materials with the half-metallic character of the electronic\nstructure. A theoretical model for the description of resonance scattering of\npolarized x-rays is suggested.",
        "positive": "Electronic structure and magnetism of transition metal doped Zn12O12\n  clusters: Role of defects: We present a comprehensive study of the energetics and magnetic properties of\nZnO clusters doped with 3d transition metals (TM) using ab initio density\nfunctional calculations in the framework of generalized gradient approximation\n+ Hubbard U (GGA+U) method. Our results within GGA+U for all 3d dopants except\nTi indicate that antiferromagnetic interaction dominates in a neutral,\ndefect-free cluster. Formation energies are calculated to identify the stable\ndefects in the ZnO cluster. We have analyzed in details the role of these\ndefects to stabilize ferromagnetism when the cluster is doped with Mn, Fe, and\nCo. Our calculations reveal that in the presence of charged defects the\ntransition metal atoms residing at the surface of the cluster may have an\nunusual oxidation state, that plays an important role to render the cluster\nferromagnetic. Defect induced magnetism in ZnO clusters without any TM dopants\nis also analyzed. These results on ZnO clusters may have significant\ncontributions in the nanoengineering of defects to achieve desired\nferromagnetic properties for spintronic applications."
    },
    {
        "anchor": "Influence of surface diffusion on catalytic reactivity of spatially\n  inhomogeneous surfaces mean field modeling: Kinetics of model catalytic processes proceeding on inhomogeneous surfaces is\nstudied. We employ an extended mean-field model that takes into account surface\ninhomogeneities. The influence of surface diffusion of adsorbent on the\nkinetics of the catalytic process is investigated. It is shown that diffusion\nis responsible for differences in the reaction rate of systems with different\narrangements of active sites. The presence of cooperative effects between\ninactive and active sites is demonstrated and the conditions when these effects\nare important are discussed. We show that basic catalytic phenomena on\nnonuniform surfaces can be studied with mean-field modeling methods.",
        "positive": "Structure and stability of Ba-Cu-Ge type-I clathrates: We have prepared samples of nominal type Ba(8)Cu(x)Ge(46-x) by induction\nmelting and solid state reaction. Analysis shows that these materials form\ntype-I clathrates, with copper content between x = 4.9 and 5.3, nearly\nindependent of the starting composition. We used x-ray powder diffraction and\nsingle-crystal electron diffraction to confirm the cubic type-I clathrate\nstructure, while electron microprobe measurements confirmed the stability of\nthe x = 5 composition. This result differs from the corresponding Ag and Au\nclathrates, and was not known previously due perhaps to the similar Cu and Ge\nform factors in x-ray diffraction. The observed composition adheres very\ntightly to a valence-counting scheme, in agreement with a Zintl-type stability\nmechanism. This implies a gap in the electronic density of states, also in\ncontrast to the metallic behavior of the Au and Ag analogs. Magnetization\nmeasurements showed a large diamagnetic response in the Ba-Cu-Ge clathrate.\nThis behavior is consistent with semiconducting or semimetallic behavior, and\nis similar to that of a number of intermetallic semiconductors."
    },
    {
        "anchor": "Chemical Diffusion at Mixed Ionic Electronic Semiconductor Interfaces\n  and comparison with La2NiO4+d epitaxial thin films: A simple model to describe Mixed Ionic Electronic Conductors (MIEC) in terms\nof standard semiconductor physics is described. This model allows to understand\ndefect equilibrium and charge transport at ideal heterojunctions between\nmaterials simultaneously conducting electronic and ionic point defects and to\nexplore how rectifying effects on the electronic or ionic currents may affect\nthe chemical diffusion and voltage at the interfaces under polarization. We\nfound qualitatively good agreement with experimental measurements of the\nelectrical conductivity relaxation of La2NiO4+d thin films epitaxially grown on\nNdGaO3 (110) substrates when the possible oxygen exchange between film and\nsubstrate is taken into account. We discuss the implications of this model to\nunderstand space charge layer formation and chemical diffusion on oxide thin\nfilm heterostructures when exposed to high temperatures and different oxygen\npartial pressures.",
        "positive": "Boosting photocatalytic water splitting of polymeric C$_{60}$ by reduced\n  dimensionality from 2D monolayer to 1D chain: Recent synthesis of monolayer fullerene networks [$Nature$ 606, 507 (2022)]\nprovides new opportunities for photovoltaics and photocatalysis because of\ntheir versatile crystal structures for further tailoring of electronic, optical\nand chemical function. To shed light on the structural aspects of\nphotocatalytic water splitting performance of fullerene nanomaterials, we\ncompare the photocatalytic properties of individual polymeric fullerene chains\nand monolayer fullerene networks from first principles calculations. It is\nfound that the photocatalytic efficiency can be further optimised by reducing\ndimensionality from 2D to 1D. The conduction band edge of the polymeric\nC$_{60}$ chain provides a much higher external potential for the hydrogen\nreduction reaction than its monolayer counterparts over a wider range of pH\nvalues, and the surface active sites in the 1D chain are two times more than\nthose in the 2D networks from a thermodynamic perspective. These observations\nrender the 1D fullerene polymer a more promising candidate as a photocatalyst\nfor the hydrogen evolution reaction than monolayer fullerene networks."
    },
    {
        "anchor": "Analysis of over-magnetization of elemental transition metal solids from\n  the SCAN Density Functional: Recent investigations have found that the strongly constrained and\nappropriately normed (SCAN) meta-GGA exchange-correlation functional\nsignificantly over-magnetizes elemental Fe, Co, and Ni solids. For the\nparadigmatic case, bcc Fe, the error relative to experiment is $\\gtrsim 20 \\%$.\nComparative analysis of magnetization results from SCAN and its\n\\textit{deorbitalized} counterpart, SCAN-L, leads to identification of the\nsource of the discrepancy. It is not from the difference between Kohn-Sham\n(SCAN-L) and generalized Kohn-Sham (SCAN) procedures. The key is the\niso-orbital indicator $\\alpha$ (the ratio of the local Pauli and Thomas-Fermi\nkinetic energy densities). Its \\textit{deorbitalized} counterpart, $\\alpha_L$,\nhas more dispersion in both spin channels with respect to magnetization in an\napproximate region between 0.6 Bohr and 1.2 Bohr around an Fe nucleus. The\noverall effect is that the SCAN switching function evaluated with $\\alpha_L$\nreduces the energetic disadvantage of the down channel with respect to up\ncompared to the original $\\alpha$, which in turn reduces the magnetization.\nThis identifies the cause of the SCAN magnetization error as insensitivity of\nthe SCAN switching function to $\\alpha$ values in the approximate range $0.5\n\\lesssim \\alpha \\lesssim 0.8$ and oversensitivity for $\\alpha \\gtrsim 0.8$.",
        "positive": "Metal-insulator transition and electroresistance in lanthanum/calcium\n  manganites La_<1-x>Ca_<x>MnO_<3> (x = 0-0.5) from voltage-current-temperature\n  surfaces: Of the perovskites, ABX_<3>, a subset of special interest is the family in\nwhich the A site is occupied by a lanthanide ion, the B site by a rare earth\nand X is oxygen, as such materials often exhibit a large change in electrical\nresistance in a magnetic field, a phenomenon known as \"colossal\"\nmagnetoresistance (MR). Two additional phenomena in this family have also drawn\nattention: the metal-insulator transition (MIT) and electroresistance (ER). The\nMIT is revealed by measuring resistance as a function of temperature, and\nobserving a change in the sign of the gradient. ER - the dependence of the\nresistance on applied current - is revealed by measuring resistance as a\nfunction of applied current. Up until now, the phenomena of MIT and ER have\nbeen treated separately. Here we report simultaneous observation of the MIT and\nER in the lanthanum/calcium manganites. We accomplish this by measuring\nvoltage-current curves over a wide temperature range (10-300 K) allowing us to\nbuild up an experimental voltage surface over current-temperature axes. These\ndata directly lead to resistance surfaces. This approach provides additional\ninsight into the phenomena of electrical transport in the lanthanum/calcium\nmanganites, in particular the close connection of the maximum ER to the\noccurrence of the MIT in those cases of a paramagnetic insulator (PMI) to\nferromagnetic metal (FMM) transition."
    },
    {
        "anchor": "Resistive switching effects on the spatial distribution of phases in\n  metal-complex oxide interfaces: In order to determine the key parameters that control the resistive switching\nmechanism in metal-complex oxides interfaces, we have studied the electrical\nproperties of metal / YBa2Cu3O7-d (YBCO) interfaces using metals with different\noxidation energy and work function (Au, Pt, Ag) deposited by sputtering on the\nsurface of a YBCO ceramic sample. By analyzing the IV characteristics of the\ncontact interfaces and the temperature dependence of their resistance, we\ninferred that ion migration may generate or cancel conducting filaments, which\nmodify the resistance near the interface, in accordance with the predictions of\na recent model.",
        "positive": "The multifunctionality of lanthanum-strontium cobaltite nanopowder:\n  high-pressure magnetic and excellent electrocatalytic properties for OER: Simultaneous study of magnetic and electrocatalytic properties of cobaltites\nunder extreme conditions expands understanding of physical and chemical\nprocesses proceeding in them with the possibility of their further practical\napplication. Therefore, La0.6Sr0.4CoO3 (LSCO) nanopowders have been synthesized\nat different annealing temperatures tann = 850, 875, 900 C, and their\nmultifunctional properties have been studied comprehensively. As tann\nincreases, the rhombohedral perovskite structure of the LSCO becomes more\nsingle-phase, whereas average particle size and dispersion grow. Co ions are in\nmixed valence states, including major Co3+ and Co4+ components. It has been\nfound that the LSCO-900 shows two main Curie temperatures, TC1 and TC2,\nassociated with a particle size distribution. As an external hydrostatic\npressure P increases, average <TC1> and <TC2> increase from 253 and 175 K under\nambient pressure to 268 and 180 K under P = 0.8 GPa, respectively. At the same\ntime, the antiferromagnetic temperature TAFM and blocking temperature TB also\nincrease from 145 and 169 K to 158 and 170 K, respectively. The increment of\n<dTC/dP> for the smaller and bigger particles is sufficiently high and equals\n10 and 13 K/GPa, respectively. The magnetocaloric effect in the LSCO-900\nnanopowder is relatively weak but with an extremely wide peak > 50 K that makes\nthis composition interesting to be used as one of the components of the\ncomposite expanding its working temperature window. Moreover, all LSCO samples\nshowed excellent electrocatalytic performance for the overall water splitting\n(OER) process (overpotentials only 265-285 mV at a current density of 10\nmA/cm2) with minimal values for LSCO-900. Based on the XPS data, it was found\nthat the formation of a dense amorphous layer on the surface of the particles\nensures high stability as a catalyst (at least 24 h) during electrolysis in 1 M\nKOH electrolyte."
    },
    {
        "anchor": "Ab initio theory of the spin-dependent conductivity tensor and the spin\n  Hall effect in random alloys: We present an extension of the relativistic electron transport theory for the\nstandard (charge) conductivity tensor of random alloys within the tight-binding\nlinear muffin-tin orbital method to the so-called spin-dependent conductivity\ntensor, which describes the Kubo linear response of spin currents to external\nelectric fields. The approach is based on effective charge- and spin-current\noperators, that correspond to intersite electron transport and that are\nnonrandom, which simplifies the configuration averaging by means of the\ncoherent potential approximation. Special attention is paid to the Fermi sea\nterm of the spin-dependent conductivity tensor, which contains a nonzero\nincoherent part, in contrast to the standard conductivity tensor. The developed\nformalism is applied to the spin Hall effect in binary random nonmagnetic\nalloys, both on a model level and for Pt-based alloys with an fcc structure. We\nshow that the spin Hall conductivity consists of three contributions (one\nintrinsic and two extrinsic) which exhibit different concentration dependences\nin the dilute limit of an alloy. Results for selected Pt alloys (Pt-Re, Pt-Ta)\nlead to the spin Hall angles around 0.2; these sizable values are obtained for\ncompositions that belong to thermodynamically equilibrium phases. These alloys\ncan thus be considered as an alternative to other systems for efficient charge\nto spin conversion, which are often metastable crystalline or amorphous alloys.",
        "positive": "Magnetic Relaxation in Two Dimensional Assembly of Dipolar Interacting\n  Nanoparticles: Using the two-level approximation of the energy barrier, we perform extensive\nkinetic Monte Carlo simulations to probe the relaxation characteristics in a\ntwo-dimensional ($L^{}_x\\times L^{}_y$) array of magnetic nanoparticle as a\nfunction of dipolar interaction strength $h^{}_d$, aspect ratio\n$A^{}_r=L^{}_y/L^{}_x$, and temperature $T$. In the case of weak dipolar\ninteraction ($h^{}_d\\approx0$) and substantial temperature, the magnetic\nrelaxation follows the N\\'eel Brown model as expected. Interestingly, the\ndipolar interaction of enough strength is found to induce antiferromagnetic\ncoupling in the square arrangement of MNPs ($A^{}_r=1.0$), resulting in the\nfastening of magnetic relaxation with $h^{}_d$. There is also a rapid increase\nin relaxation even with $A^{}_r<100$ above a particular dipolar interaction\nstrength $h^{\\star}_d$, which gets enhanced with $A^{}_r$. Remarkably, there is\na slowing down of magnetic relaxation with $h^{}_d$ for the highly anisotropic\nsystem such as linear chain of MNPs. It is because the dipolar interaction\ninduces ferromagnetic interaction in such a case. The thermal fluctuations also\naffect the relaxation properties drastically. In the case of weak dipolar\nlimit, magnetization relaxes rapidly with $T$ because of enhancement in thermal\nfluctuations. The effect of dipolar interaction and aspect ratio on the\nmagnetic relaxation is also clearly indicated in the variation of N\\'eel\nrelaxation time $\\tau^{}_N$. In the presence of strong dipolar interaction\n($h^{}_d>0.3$) and $A^{}_r=1.0$, $\\tau^{}_N$ decreases with $h^{}_d$ for a\ngiven temperature. On the other hand, there is an increase in $\\tau^{}_N$ with\n$h^{}_d$ for huge $A^{}_r$ $(>100)$. We believe that the concepts presented in\nthis work are beneficial for the efficient use of self-assembled MNPs array in\ndata storage and other related applications."
    },
    {
        "anchor": "Coexistence of multiple interfacial states at heterogeneous solid/liquid\n  interface: The growing trend towards engineering interfacial complexion (or phase)\ntransitions has been seen in the grain boundary and solid surface\nsystems.Meanwhile, little attention has been paid to the chemically\nheterogeneous solid/liquid interfaces. In this work, novel in-plane\nmulti-interfacial states coexist within the Cu(111)/Pb(l) interface at a\ntemperature just above the Pb freezing point is uncovered using atomistic\nsimulations.Four monolayer interfacial states, i.e., two CuPb alloy liquids and\ntwo pre-freezing Pb solids, are observed coexisting within two interfacial\nlayers sandwiched between the bulk solid Cu and bulk liquid Pb. Through\ncomputing the spatial variations of various properties along the direction\nnormal to the in-plane solid-liquid boundary lines for both interfacial layers,\na rich and varied picture depicting the inhomogeneity and anisotropy in the\nmechanical, thermodynamical, and dynamical properties is presented. The bulk\nvalues extracted from the in-plane profiles suggest that each interfacial state\nexamined has distinct equilibrium values from each other and significantly\ndeviates from those of the bulk solid and liquid phases, and indicate that the\ncomplexion (or phase) diagrams for the Cu(111)/Pb(l) interface bears a\nresemblance to that of the eutectic binary alloy systems, instead of the\nmonotectic phase diagram for the bulk CuPb alloy. The reported data could\nsupport the development of interfacial complexion (or phase) diagrams and\ninterfacial phase rules and provide a new guide for regulating heterogeneous\nnucleation and wetting processes.",
        "positive": "Meshless simulation for thermo-mechanical properties of single-walled\n  carbon nanotubes based on the thermal-related higher order Cauchy-Born rule: In the present paper, a temperature-dependent meshless numerical framework\nbased on the thermo-related quasi-continuum constitutive model is developed for\npredicting the thermal mechanical properties of single-walled carbon nanotubes\n(SWCNTs) at finite temperature. The extended thermal-related higher order\nCauchy-Born (THCB) rule included second order deformation gradient relates the\ndeformation of bond vectors of the atomic system and that of the continuous\nmedium, which can capture the curvature effect of carbon nanotubes (CNTs)\nconveniently. Helmholtz free energy is employed to allow for the thermal effect\nof SWCNTs. In the meshless numerical implementations of the theory, the Newton\niteration method is applied to find the equilibrium configuration of a SWCNT\nsubjected to large deformation at a prescribed temperature only with the nodal\ndisplace parameters as optimization variables. The finite deformation behaviors\nof armchair and zigzag SWCNTs under axial compression and torsion are tested.\nIt is shown that the simulation results are in good agreement with those\nobtained by molecular dynamic methods even with fewer meshless nodes used."
    },
    {
        "anchor": "Time Driven Subwavelength Focusing with Negative Refraction: Flat lens concept based on negative refraction proposed by Veselago in 1968\nhas been mostly investigated in monochromatic regime. It was recently\nrecognized that time development of the super-lensing effect discovered in 2000\nby Pendry is yet to be assessed and may spring surprises: Time-dependent\nillumination could improve the spatial resolution of the focusing. We\ninvestigate dynamics of flexural wave focusing by a 45\\degre-tilted square\nlattice of circular holes drilled in a Duraluminium plate. Time-resolved\nexperiments reveal that the focused image shrinks with time below diffraction\nlimit, with a lateral resolution increasing from 0.8 $\\lambda$ to 0.35\n$\\lambda$, whereas focusing under harmonic excitation remains diffraction\nlimited. Modal analysis reveals the role in pulse reconstruction of radiating\nlens resonances, which repeatedly self-synchronize at the focal spot to shape a\nsuper-oscillating field.",
        "positive": "Epitaxial Growth of Monolayer PdTe2 and Patterned PtTe2 by Direct\n  Tellurization of Pd and Pt surfaces: Two-dimensional (2D) palladium ditelluride (PdTe2) and platinum ditelluride\n(PtTe2) are two Dirac semimetals which demonstrate fascinating quantum\nproperties such as superconductivity, magnetism and topological order,\nillustrating promising applications in future nanoelectronics and\noptoelectronics. However, the synthesis of their monolayers is dramatically\nhindered by strong interlayer coupling and orbital hybridization. In this\nstudy, an efficient synthesis method for monolayer PdTe2 and PtTe2 is\ndemonstrated. Taking advantages of the surface reaction, epitaxial growth of\nlarge-area and high quality monolayers of PdTe2 and patterned PtTe2 is achieved\nby direct tellurization of Pd(111) and Pt(111). A well-ordered PtTe2 pattern\nwith Kagome lattice formed by Te vacancy arrays is successfully grown.\nMoreover, multilayer PtTe2 can be also obtained and potential excitation of\nDirac plasmons is observed. The simple and reliable growth procedure of\nmonolayer PdTe2 and patterned PtTe2 gives unprecedented opportunities for\ninvestigating new quantum phenomena and facilitating practical applications in\noptoelectronics."
    },
    {
        "anchor": "Structural, electronic, and magnetic properties of ZnTe doped with\n  transition metal Mn: In this article, we examine the structure and the electronic, optical, and\nmagnetic properties of ZnTe before and after doping with the transition metal\nMn. The ab initio calculations of this compound were performed using the full\npotential linearized extended full potential planar waveform (FP-LAPW) in the\ncontext of density functional theory (DFT) implemented in the Wien2K code. The\npotential for exchange and correlation was addressed by the generalized\ngradient approximation (GGA) approximation. The electronic properties show that\nthe ZnTe material exhibits semiconductor behavior before doping. As a result,\nit becomes semimetal after doping. The findings attained by Monte Carlo\nsimulations display that the ZnMnTe material goes from an antiferromagnetic\nphase to the paramagnetic phase at the Neel temperature value TN =159.31 K.",
        "positive": "Electronic structure study by means of X-ray spectroscopy and\n  theoretical calculations of the \"ferric star\" single molecule magnet: The electronic structure of the single molecule magnet system\nM[Fe(L)2]3*4CHCl3 (M=Fe,Cr; L=CH3N(CH2CH2O)2) has been studied using X-ray\nphotoelectron spectroscopy, X-ray absorption spectroscopy, soft X-ray emission\nspectroscopy, and density functional calculations. There is good agreement\nbetween theoretical calculations and experimental data. The valence band mainly\nconsists of three bands between 2 eV and 30 eV. Both theory and experiments\nshow that the top of the valence band is dominated by the hybridization between\nFe 3d and O 2p bands. From the shape of the Fe 2p spectra it is argued that Fe\nin the molecule is most likely in the 2+ charge state. Its neighboring atoms\n(O,N) exhibit a magnetic polarisation yielding effective spin S=5/2 per iron\natom, giving a high spin state molecule with a total S=5 effective spin for the\ncase of M = Fe."
    },
    {
        "anchor": "Energy Localization Efficiency in TATB Pore Collapse Mechanisms: Atomistic and continuum scale modeling efforts have shown that shock induced\ncollapse of porosity can occur via a wide range of mechanisms dependent on pore\nmorphology, shockwave pressure, and material properties. The mechanisms that\noccur under weaker shocks tend to be more efficient at localizing thermal\nenergy, but do not result in high, absolute temperatures or spatially large\nlocalizations compared to mechanisms found under strong shock conditions.\nHowever, the energetic material TATB undergoes a wide range of collapse\nmechanisms that are not typical of similar materials, leaving the collapse\nmechanisms and the resultant energy localization from collapse, i.e., hotspots,\nrelatively uncharacterized. Therefore, we present pore collapse simulations of\ncylindrical pores in TATB for a wide range of pore sizes and shock strengths\nthat trigger viscoplastic collapses that occur almost entirely perpendicular to\nthe shock direction for weak shocks and hydrodynamic-like collapses for strong\nshocks that do not break the strong hydrogen bonds of the TATB basal planes.\nThe resulting hotspot temperature fields from these mechanisms follow trends\nthat differ considerably from other energetic materials; hence we compare them\nunder normalized temperature values to assess the relative efficiency of each\nmechanism to localize energy. The local intra-molecular strain energy of the\nhotspots is also assessed to better understand the physical mechanisms behind\nthe phenomena that leads to a latent potential energy.",
        "positive": "Surface structures of ZrO$_2$ films on Rh(111): From two layers to bulk\n  termination: We have studied zirconia films on a Rh(111) substrate with thicknesses in the\nrange of 2-10 monolayers (ML) using scanning tunneling microscopy (STM) and\nlow-energy electron diffraction (LEED). Zirconia was deposited using a\nUHV-compatible sputter source, resulting in layer-by-layer growth and good\nuniformity of the films. For thicknesses of 2-4 ML, a layer-dependent influence\nof the substrate on the structure of the thin films is observed. Beyond this\nthickness, films show a (2 $\\times$ 1) or a distorted (2 $\\times$ 2) surface\nstructure with respect to cubic ZrO$_2$(111); these structures correspond to\ntetragonal and monoclinic zirconia, respectively. The tetragonal phase occurs\nfor annealing temperatures of up to 730 {\\deg}C; transformation to the\nthermodynamically stable monoclinic phase occurs after annealing at 850 {\\deg}C\nor above. High-temperature annealing also breaks up the films and exposes the\nRh(111) substrate. We argue that the tetragonal films are stabilized by oxygen\ndeficiency, while the monoclinic films are only weakly defective and show band\nbending at defects and grain boundaries. This observation is in agreement with\npositive charge being responsible for the grain-boundary blocking effect in\nzirconia-based solid electrolytes. Our work introduces the tetragonal and\nmonoclinic 5 ML-thick ZrO$_2$ films on Rh(111) as well-suited model system for\nsurface-science studies on ZrO$_2$ as they do not exhibit the charging problems\nof thicker films or the bulk material and show better homogeneity and stability\nthan the previously-studied ZrO$_2$/Pt(111) system."
    },
    {
        "anchor": "Causes of ferroelectricity in HfO$_{2}$-based thin films: An $\\textit{ab\n  initio}$ perspective: We present a comprehensive first principles study of doped hafnia in order to\nunderstand the formation of the ferroelectric orthorhombic [001] grains.\nAssuming that tetragonal grains are present during the early stages of growth,\nmatching plane analysis shows that tetragonal [100] grains can transform into\northorhombic [001] during thermal annealing, when they are laterally confined\nby other grains. We show that among 0%, 2% and %4 Si doping, 4% doping provides\nthe best conditions for the tetragonal [100] to orthorhombic [001]\ntransformation. This also holds for Al doping. We also show that for\nHf$_{x}$Zr$_{1-x}$O$_{2}$, where we have studied\n${x}=1.00,0.75,0.50,0.25,0.00$, the value ${x}=0.50$ provides the most\nfavorable conditions for the desired transformation. In order for this\ntransformation to be preferred over the tetragonal [100] to monoclinic [100]\ntransformation, out-of-plane confinement also needs to be present, as supplied\nby a top electrode. Our findings illuminate the mechanism that causes\nferroelectricity in hafnia-based films and provide an explanation for common\nexperimental observations for the optimal ranges of doping in Si:HfO$_{2}$,\nAl:HfO$_{2}$ and Hf$_{x}$Zr$_{1-x}$O$_{2}$. We also present model thin film\nheterostructure computations of Ir/HfO$_{2}$/Ir stacks in order to isolate the\ninterface effects, which we show to be significant.",
        "positive": "Delayed formation of coherent LO phonon-plasmon coupled modes in n-type\n  and p-type GaAs measured using a femtosecond coherent control technique: Coherent control experiments using a pair of collinear femtosecond laser\npulses have been carried out to manipulate longitudinal optical (LO)\nphonon-plasmon coupled (LOPC) modes in both p- and n-type GaAs. By tuning the\ninterpulse separation, remarkably distinct responses have been observed in the\ntwo samples. To understand the results obtained a phenomenological model taking\nthe delayed formation of coherent LOPC modes into account is proposed. The\nmodel suggests that the lifetime of coherent LOPC modes plays a key role and\nthe interference of the coherent LO phonons excited successively by two pump\npulses strongly affects the manipulation of coherent LOPC modes."
    },
    {
        "anchor": "Localization of Yttrium Segregation within YSZ Grain Boundary\n  Dislocation Cores: Ionic conductivity blocking at grain boundaries in polycrystalline\nelectrolytes is one of the main obstacles that need to be overcome in order to\nimprove the performance of solid state fuel cells and batteries. To this aim,\nharnessing the physical properties of grain boundaries in ionic conducting\nmaterials such as yttria stabilized zirconia (YSZ) down to the atomic scale\narises as a greatly important task. Here we present a structural and\ncompositional analysis of a single grain boundary in a 9 mol% yttria content\nYSZ bicrystal by means of aberration corrected scanning transmission electron\nmicroscopy. Our studies combine strain and compositional atomic resolution\nanalysis with density-functional-theory calculations in order to find a\npreferential segregation of yttrium to the expansive atomic sites at the grain\nboundary dislocation cores. These results address a crucial step towards the\nunderstanding of the physical properties of grain boundaries down to atomic\ndimensions.",
        "positive": "Ordering of atomic mono-layers on a (001) cubic crystal surface: The self-organization of a chemi-sorbed mono-layer is studied as a two\ndimensional ordering process in presence of surface stress. As proved\npreviously for a single phase separation, a steady surface state is yielded\nfrom the competition between the domain boundary energy and the surface stress\nelastic energy. In the present letter, the resulting patterns are shown to\ndepend on the interplay between the symmetries of both the internal layer order\nand the underlying crystal. For experimental relevance, our study is focussed\non a (001) copper surface and we believe to enhance a route to stabilize novel\nsurface nanostructures."
    },
    {
        "anchor": "Correlations in the chain melting of host-guest Calcium: In this paper, we study chain melting state in the commensurate host-guest\nstructure of calcium. We trained a NN (neural network) force field with\nDeepMD-kit, and by implementing classical simulations, we found that the\nconvergence of z-proejcted MSD of guest atoms needs at least 8192-atom\nsupercell. We ascribe the origination of chain melting to the phase transition\nat 600 K, in which the arrangement of guest chains transform from a\ncheckerboard pattern to a stripe pattern, and the energy barrier of sliding\nchains against each other is obviously reduced. We also found that the chain\nmelting state of calcium could be separated into two 2D (two-dimensional) and\n3D (three-dimensional) disorder, with distinct chain dynamics.",
        "positive": "Direct Evidence of Metallic Bands in a Monolayer Boron Sheet: The search for metallic boron allotropes has attracted great attention in the\npast decades and recent theoretical works predict the existence of metallicity\nin monolayer boron. Here, we synthesize the \\b{eta}12-sheet monolayer boron on\na Ag(111) surface and confirm the presence of metallic boron-derived bands\nusing angle-resolved photoemission spectroscopy. The Fermi surface is composed\nof one electron pocket at the S point and a pair of hole pockets near the X\npoint, which is supported by the first-principles calculations. The metallic\nboron allotrope in \\b{eta}12 sheet opens the way to novel physics and chemistry\nin material science."
    },
    {
        "anchor": "Topological transitions to Weyl states in bulk Bi$_2$Se$_3$: Effect of\n  hydrostatic pressure and doping: Bi$_2$Se$_3$, a layered three dimensional (3D) material, exhibits topological\ninsulating properties due to presence of surface states and a band gap of 0.3\neV in the bulk. We study the effect hydrostatic pressure $P$ and doping with\nrare earth elements on the topological aspect of this material in bulk from a\nfirst principles perspective. Our study shows that under a moderate pressure of\nP$>$7.9 GPa, the bulk electronic properties show a transition from an\ninsulating to a Weyl semi-metal state due to band inversion. This electronic\ntopological transition may be correlated to a structural change from a layered\nvan der Waals material to a 3D system observed at $P$=7.9 GPa. At large $P$\ndensity of states have significant value at the Fermi-energy. Intercalating Gd\nwith a small doping fraction between Bi$_2$Se$_3$ layers drives the system to a\nmetallic anti-ferromagnetic state, with Weyl nodes below the Fermi-energy. At\nthe Weyl nodes time reversal symmetry is broken due to finite local field\ninduced by large magnetic moments on Gd atoms. However, substituting Bi with Gd\ninduces anti-ferromagnetic order with an increased direct band gap. Our study\nprovides novel approaches to tune topological transitions, particularly in\ncapturing the elusive Weyl semimetal states, in 3D topological materials.",
        "positive": "Magnetoelasticity-driven phase inversion of ultrafast spin precession in\n  NixFe100-x thin films: We present strong evidences for the deterministic role of magnetoelasticity\nin ultrafast spin dynamics of ferromagnetic NixFe100-x alloy films. Without a\nchange in the crystal structure, we observed sudden Pi-phase inversion of the\nspin precession in the range of x = 87.0 - 97.5. In addition, it was found that\nthe phase was continuously changed and reversed its sign by varying the pump\nfluence. These cannot be explained simply by temperature dependence of\nmagnetocrystalline, demagnetizing, and Zeeman fields which have been\nconventionally considered so far in describing the spin dynamics. Through the\ntemperature- and composition-dependent simulations adding the magnetoelastic\nfield generated from the lattice thermal strain, we revealed that the\nconventional and magnetoelastic fields were competing around x = 95.3, where\nthe spin dynamics showed the largest phase shift. For analytic understanding,\nwe further show that the temperature-dependent interplay of the Curie\ntemperature, saturation magnetization, and magnetostriction, which are\ndemonstrated to be the most important macroscopic parameters, determines the\nultrafast spin dynamics. Our extensive study emphasizes that magnetoelasticity\nis the key ingredient for fully understanding the driving mechanism of\nultrafast spin dynamics."
    },
    {
        "anchor": "Interfacial properties of 2D WS2 on SiO2 substrate from x-ray\n  photoelectron spectroscopy and first-principles calculations: Two-dimensional (2D) WS2 films were deposited on SiO2 wafers, and the related\ninterfacial properties were investigated by high-resolution x-ray photoelectron\nspectroscopy (XPS) and first-principles calculations. Using the direct\n(indirect) method, the valence band offset (VBO) at monolayer WS2/SiO2\ninterface was found to be 3.97 eV (3.86 eV), and the conduction band offset\n(CBO) was 2.70 eV (2.81 eV). Furthermore, the VBO (CBO) at bulk WS2/SiO2\ninterface is found to be about 0.48 eV (0.33 eV) larger due to the interlayer\norbital coupling and splitting of valence and conduction band edges. Therefore,\nthe WS2/SiO2 heterostructure has a Type I energy-band alignment. The band\noffsets obtained experimentally and theoretically are consistent except the\nnarrower theoretical bandgap of SiO2. The theoretical calculations further\nreveal a binding energy of 75 meV per S atom and the totally separated partial\ndensity of states, indicating a weak interaction and negligible Fermi level\npinning effect between WS2 monolayer and SiO2 surface. Our combined\nexperimental and theoretical results provide proof of the sufficient VBOs and\nCBOs and weak interaction in 2D WS2/SiO2 heterostructures.",
        "positive": "Creating and modulating electronic states on noble metal surfaces:\n  ultrathin Ag islands on Si(111)-7$\\times$7 as a prototype: Various-thickness Ag islands were prepared on Si(111)-7$\\times$7 using the\none-step deposition at a high substrate temperature. An electronic state\ncentered at -0.40$\\sim$-0.15eV versus E$_{Fermi}$, detectable on the surface of\nthe Ag islands thinner than 9 layers, was created by the electronic\nhybridization between Ag and Si at the Ag-Si interface. Scanning tunneling\nmicroscopy/spectroscopy and density functional theory revealed that the\nthickness of Ag islands determined the strength of the hybridization, leading\nto a modulation to the energy and intensity of the state on the surface."
    },
    {
        "anchor": "Entering voltage hysteresis in phase separating materials: revealing the\n  thermodynamic origin of a newly discovered phenomenon and its impact on the\n  electric response of a battery: Hysteresis is a general phenomenon regularly observed in measurements of\nvarious materials properties such as magnetism, elasticity, capillary pressure,\nadsorption, battery voltage etc. Usually, the hysteretic behaviour is an\nintrinsic property that cannot be avoided or circumvented in dynamic operation\nof the system. Here we show, however, that at least as regards the hysteretic\nbehaviour of phase-separating battery materials, one can enter (deeply) into\nthe hysteretic loop in specific, yet realistic, transient operating conditions.\nWithin the hysteretic loop a (significant) portion of particle population\nresides in an intraparticle phase separated state. Interestingly, the\ntransition to the more conventional interparticle phase separation state found\noutside the hysteretic loop is very slow. Further, we establish a direct\ninterrelation between the intraparticle phase separated electrode state and\naltered electric response of the electrode, which significantly impacts DC and\nAC characteristics of the battery. The experimental evidence of entering the\nhysteretic loop and the resulting altered response of the battery are explained\nbased on thermodynamic reasoning, advanced modelling and insightful\nexperiments. We believe that the understanding of this phenomenon will help\noptimise the diagnostics and monitoring of batteries, while also providing\npertinent motivation for the enhancement of battery design and performance.",
        "positive": "Analysis of incubation time preceding the Ga-assisted nucleation and\n  growth of GaAs nanowires on Si(111): The incubation time preceding nucleation and growth of surface nanostructures\nis interesting from a fundamental viewpoint but also of practical relevance as\nit determines statistical properties of nanostructure ensembles such as size\nhomogeneity. Using in situ reflection high-energy electron diffraction, we\naccurately deduce the incubation times for Ga-assisted GaAs nanowires grown on\nunpatterned Si(111) substrates by molecular beam epitaxy under different\nconditions. We develop a nucleation model that explains and fits very well the\ndata. We find that, for a given temperature and Ga flux, the incubation time\nalways increases with decreasing As flux and becomes infinite at a certain\nminimum flux, which is larger for higher temperature. For given As and Ga\nfluxes, the incubation time always increases with temperature and rapidly tends\nto infinity above 640 {\\deg}C under typical conditions. The strong temperature\ndependence of the incubation time is reflected in a similar variation of the\nnanowire number density with temperature. Our analysis provides understanding\nand guidance for choosing appropriate growth conditions that avoid unnecessary\nmaterial consumption, long nucleation delays, and highly inhomogeneous\nensembles of nanowires. On a more general ground, the existence of a minimum\nflux and maximum temperature for growing surface nanostructures should be a\ngeneral phenomenon pertaining for a wide range of material-substrate\ncombinations."
    },
    {
        "anchor": "Thermal conductivity reduction in\n  (Zr$_{0.25}$Ta$_{0.25}$Nb$_{0.25}$Ti$_{0.25}$)C high entropy carbide from\n  extrinsic lattice defects: High entropy carbides ceramics with randomly-distributed multiple principal\ncations have shown high temperature stability, low thermal conductivity, and\npossible radiation tolerance. While chemical disorder has been shown to\nsuppress thermal conductivity in these materials, little investigation has been\nmade on the effects of additional, extrinsically-generated structural defects\non thermal transport. Here, (Zr$_{0.25}$Ta$_{0.25}$Nb$_{0.25}$Ti$_{0.25}$)C is\nexposed to Zr ions to generate a micron-scale, structural-defect-bearing layer.\nThe reduction in lattice thermal transport is measured using laser\nthermoreflectance. Conductivity changes from different implantation\ntemperatures suggest dislocation loops contribute little to phonon scattering\nwhile nanoscale defects serve as effective scatterers, offering a pathway for\nthermal engineering.",
        "positive": "Ferroelectricity Driven by Twisting of Silicate Tetrahedral Chains: Conventional perovskite-type ferroelectrics are based on octahedral units of\noxygen, and often comprise toxic Pb to achieve robust ferroelectricity. Here,\nwe report the ferroelectricity in a silicate-based compound, Bi2SiO5 (BSO),\ninduced by a structural instability of the corresponding silicate tetrahedral\nchains. A low-energy phonon mode condenses at ~ 673 K to induce the proper\nferroelectric phase transition. Polarization switching was observed in a BSO\nsingle crystal with a coercive field of 30 kV/cm and a spontaneous polarization\nof 0.3 microC/cm2 along a direction normal to the cleavage plane. The in-plane\npolarization was estimated by first principles calculations to be 23\nmicroC/cm2. The present findings provide a new guideline for designing\nferroelectric materials based on SiO4 tetrahedral units, which is ubiquitously\nfound in natural minerals."
    },
    {
        "anchor": "Ising and XY paramagnons in two-dimensional 2H-NbSe$_2$: Paramagnons are the collective modes that govern the spin response of nearly\nmagnetic conductors. In some cases they mediate electron pairing leading to\nsuperconductivity. This scenario may occur in 2H-NbSe$_2$ monolayers, that\nfeature spin-valley coupling on account of spin-orbit interactions and their\nlack of inversion symmetry. Here we explore spin anisotropy of paramagnons both\nfor non-centrosymmetric Kane-Mele-Hubbard models for 2H-NbSe$_2$ monolayers\ndescribed with a DFT-derived tight-binding model. In the infinite wavelength\nlimit we find spatially uniform paramagnons with energies around $1$~meV that\nfeature a colossal off-plane uniaxial magnetic anisotropy, with quenched\ntransversal spin response. At finite wave vectors, longitudinal and transverse\nchannels reverse roles: XY fluctuations dominate within a significant portion\nof the Brillouin zone. Our results show that 2H-NbSe$_2$ is close to a\nCoulomb-driven in-plane (XY) spin density wave instability.",
        "positive": "Ab Initio Many-body Study of Cobalt Adatoms Adsorbed on Graphene: Many recent calculations have been performed to study a Co atom adsorbed on\ngraphene, with significantly varying results on the nature of the bonding. We\nuse auxiliary-field quantum Monte Carlo (AFQMC) and a size-correction embedding\nscheme to accurately calculate the binding energy of Co on graphene. We find\nthat as a function of the distance h between the Co atom and the six-fold\nhollow site, there are three distinct ground states corresponding to three\nelectronic configurations of the Co atom. Two of these states provide binding\nand exhibit a double-well feature with nearly equal binding energy of 0.4 eV at\nh = 1.51 and h = 1.65 angstroms, corresponding to low-spin $^2$Co (3d9 4s0) and\nhigh-spin $^4$Co (3d8 4s1), respectively."
    },
    {
        "anchor": "Defect Role in the Carrier Tunable Topological Insulator\n  (Bi$_{1-x}$Sb$_x$)$_2$Te$_3$ Thin Films: Alloys of Bi$_2$Te$_3$ and Sb$_2$Te$_3$ ((Bi$_{1-x}$Sb$_x$)$_2$Te$_3$) have\nplayed an essential role in the exploration of topological surface states,\nallowing us to study phenomena that would otherwise be obscured by bulk\ncontributions to conductivity. Thin films of these alloys have been\nparticularly important for tuning the energy of the Fermi level, a key step in\nobserving spin-polarized surface currents and the quantum anomalous Hall\neffect. Previous studies reported the chemical tuning of the Fermi level to the\nDirac point by controlling the Sb:Bi composition ratio, but the optimum ratio\nvaries widely across various studies with no consensus. In this work, we use\nscanning tunneling microscopy and Landau level spectroscopy, in combination\nwith X-ray photoemission spectroscopy to isolate the effects of growth factors\nsuch as temperature and composition, and to provide a microscopic picture of\nthe role that disorder and composition play in determining the carrier density\nof epitaxially grown (Bi,Sb)$_2$Te$_3$ thin films. Using Landau level\nspectroscopy, we determine that the ideal Sb concentration to place the Fermi\nenergy to within a few meV of the Dirac point is $x\\sim 0.7$. However, we find\nthat the post- growth annealing temperature can have a drastic impact on\nmicroscopic structure as well as carrier density. In particular, we find that\nwhen films are post-growth annealed at high temperature, better crystallinity\nand surface roughness are achieved; but this also produces a larger Te defect\ndensity, adding n-type carriers. This work provides key information necessary\nfor optimizing thin film quality in this fundamentally and technologically\nimportant class of materials.",
        "positive": "The importance of intra-molecular electron spin relaxation in small\n  molecular semiconductors: Electron spin relaxation rate (eSR) is investigated on several organic\nsemiconductors of different morphologies and molecular structures, using\navoided level crossing muon spectroscopy as a local spin probe. We find that\ntwo functionalized acenes (polycrystalline tri(isopropyl)silyl-pentacene and\namorphous 5,6,11,12-tetraphenyltetracene) exhibit eSRs with an Arrhenius-like\ntemperature dependence, each with two characteristic energy scales similar to\nthose expected from vibrations. Polycrystalline tris(8-hydroxyquinolate)gallium\nshows a similar behavior. The observed eSR for these molecules is no greater\nthan 0.85 MHz at 300 K. The variety of crystal structures and transport regimes\nthat these molecules possess, as well as the local nature of the probe,\nstrongly suggest an intra-molecular phenomenon general to many organic\nsemiconductors, contrasting the commonly assumed spin relaxation models based\non inter-molecular charge carrier transport."
    },
    {
        "anchor": "ImageMech: From image to particle spring network for mechanical\n  characterization: The emerging demand for advanced structural and biological materials calls\nfor novel modeling tools that can rapidly yield high-fidelity estimation on\nmaterials properties in design cycles. Lattice spring model (LSM), a\ncoarse-grained particle spring network, has gained attention in recent years\nfor predicting the mechanical properties and giving insights into the fracture\nmechanism with high reproducibility and generalizability. However, to simulate\nthe materials in sufficient detail for guaranteed numerical stability and\nconvergence, most of the time a large number of particles are needed, greatly\ndiminishing the potential for high-throughput computation and therewith data\ngeneration for machine learning frameworks. Here, we implement CuLSM, a\nGPU-accelerated CUDA C++ code realizing parallelism over the spring list\ninstead of the commonly used spatial decomposition, which requires intermittent\nupdates on the particle neighbor list. Along with the image-to-particle\nconversion tool Img2Particle, our toolkit offers a fast and flexible platform\nto characterize the elastic and fracture behaviors of materials, expediting the\ndesign process between additive manufacturing and computer-aided design. With\nthe growing demand for new lightweight, adaptable, and multi-functional\nmaterials and structures, such tailored and optimized modeling platform has\nprofound impacts, enabling faster exploration in design spaces, better quality\ncontrol for 3D printing by digital twin techniques, and larger data generation\npipelines for image-based generative machine learning models.",
        "positive": "Hydrodynamic coarsening in phase-separated silicate melts: Using in-situ synchrotron tomography, we investigate the coarsening dynamics\nof barium borosilicate melts during phase separation. The 3-D geometry of the\ntwo interconnected phases is determined thanks to image processing. We observe\na linear growth of the size of domains with time, at odds with the sublinear\ndiffusive growth usually observed in phase-separating glasses or alloys. Such\nlinear coarsening is attributed to viscous flow inside the bicontinuous phases,\nand quantitative measurements show that the growth rate is well explained by\nthe ratio of surface tension over viscosity. The geometry of the domains is\nshown to be statistically similar at different times, provided that the\nmicrostructure is rescaled by the average domain size. Complementary\nexperiments on melts with a droplet morphology demonstrate that viscous flow\nprevails over diffusion in the large range of domain sizes measured in our\nexperiments (1 - 80 microns)."
    },
    {
        "anchor": "Reentrant semiconducting behavior in polymerized fullerite structures\n  with increasing sp3-carbon content: The electronic behavior of polymerized fullerite structures, ranging from\none-dimensional to three-dimensional polymers, was studied using density\nfunctional theory. The bandgap across these structures decreases with the rise\nof sp3-carbon content until metallic behavior is observed. A further increase\ninduces a reopening of the bandgap, revealing a reentrant semiconducting\nbehavior in this class of materials. This behavior is understood in terms of\nthe new electronic states originated by polymeric bonding and the effect of the\nvolume reduction on the dispersion of sp2-states. This study highlights the\nfullerite polymers as a magnificent platform to tune electronic properties.",
        "positive": "Inelastic hard-rods in a periodic potential: A simple model of inelastic hard-rods subject to a one-dimensional array of\nidentical wells is introduced. The energy loss due to inelastic collisions is\nbalanced by the work supplied by an external stochastic heat-bath. We explore\nthe effect of the spatial non uniformity on the steady states of the system.\nThe spatial variations of the density, granular temperature and pressure\ninduced by the gradient of the external potential are investigated and compared\nwith the analogous variations in an elastic system. Finally, we study the\nclustering process by considering the relaxation of the system starting from a\nuniform homogeneous state."
    },
    {
        "anchor": "Predicting Creep Failure by Machine Learning -- Which Features Matter?: Spatial and temporal features are studied with respect to their predictive\nvalue for failure time prediction in subcritical failure with machine learning\n(ML). Data are generated from simulations of a novel, brittle random fuse model\n(RFM), as well as elasto-plastic finite element simulations (FEM) of a\nstochastic plasticity model with damage, both models considering stochastic\nthermally activated damage/failure processes in disordered materials. Fuse\nnetworks are generated with hierarchical and nonhierarchical architectures.\nRandom forests - a specific ML algorithm - allow us to measure the feature\nimportance through a feature's average error reduction. RFM simulation data are\nfound to become more predictable with increasing system size and temperature.\nIncreasing the load or the scatter in local materials properties has the\nopposite effect. Damage accumulation in these models proceeds in stochastic\navalanches, and statistical signatures such as avalanche rate or magnitude have\nbeen discussed in the literature as predictors of incipient failure. However,\nin the present study such features proved of no measurable use to the ML\nmodels, which mostly rely on global or local strain for prediction. This\nsuggests the strain as viable quantity to monitor in future experimental\nstudies as it is accessible via digital image correlation.",
        "positive": "Observation of domain wall bimerons in chiral magnets: Topological defects embedded in or combined with domain walls have been\nproposed in various systems, some of which are referred to as domain wall\nskyrmions or domain wall bimerons. However, the experimental observation of\nsuch topological defects remains an ongoing challenge. Here, using Lorentz\ntransmission electron microscopy, we report the experimental discovery of\ndomain wall bimerons in chiral magnet Co-Zn-Mn(110) thin films. By applying a\nmagnetic field, multidomain structures develop, and simultaneously, chained and\nisolated bimerons arise as the localized state between the domains with the\nopposite in-plane components of net magnetization. The multidomain formation is\nattributed to magnetic anisotropy and dipolar interaction, and domain wall\nbimerons are stabilized by the Dzyaloshinskii-Moriya interaction. In addition,\nmicromagnetic simulations show that domain wall bimerons appear for a wide\nrange of conditions in chiral magnets with cubic magnetic anisotropy. Our\nresults promote further study in various fields of physics."
    },
    {
        "anchor": "Excitons in few-layer hexagonal boron nitride: Davydov splitting and\n  surface localization: Hexagonal boron nitride (hBN) has been attracting great attention because of\nits strong excitonic effects. Taking into account few-layer systems, we\ninvestigate theoretically the effects of the number of layers on quasiparticle\nenergies, absorption spectra, and excitonic states, placing particular focus on\nthe Davydov splitting of the lowest bound excitons. We describe how the\ninter-layer interaction as well as the variation in electronic screening as a\nfunction of layer number $N$ affects the electronic and optical properties.\nUsing both \\textit{ab initio} simulations and a tight-binding model for an\neffective Hamiltonian describing the excitons, we characterize in detail the\nsymmetry of the excitonic wavefunctions and the selection rules for their\ncoupling to incoming light. We show that for $N > 2$, one can distinguish\nbetween surface excitons that are mostly localized on the outer layers and\ninner excitons, leading to an asymmetry in the energy separation between split\nexcitonic states. In particular, the bound surface excitons lie lower in energy\nthan their inner counterparts. Additionally, this enables us to show how the\nlayer thickness affects the shape of the absorption spectrum.",
        "positive": "Photoconductivity and Photoemission of Diamond Under Femtosecond Vuv\n  Irradiation: In order to gain some insight on the electronic relaxation mechanisms\noccuring in diamond under high intensity laser excitation and/or VUV\nexcitation, we studied experimentally the pulsed conductivity induced by\nfemtosecond VUV pulses, as well as the energy spectra of the photoelectrons\nreleased by the same irradiation. The source of irradiation consists in highly\ncoherent VUV pulses obtained through high order harmonic generation of a high\nintensity femtosecond pulse at a 1.55 eV photon energy (titanium-doped sapphire\nlaser). Harmonics H9 to H17 have been used for photoconductivity (PC) and\nharmonics H13 to H27 for photoemission experiments (PES). As the photon energy\nis increased, it is expected that the high energy photoelectrons will generate\nsecondary e-h pairs, thus increasing the excitation density and consequently\nthe PC signal. This is not what we observe : the PC signal first increases for\nH9 to H13, but then saturates and even decreases. Production of low energy\nsecondary e-h pairs should also be observed in the PES spectrum. In fact we\nobserve very few low energy electrons in the PES spectrum obtained with H13 and\nH15, despite the sufficient energy of the generated free carriers. At the other\nend (H21 and above), a very intense low energy secondary electron peak is\nobserved. As a help to interprete such data, we realized the first ab initio\ncalculations of the electronic lifetime of quasiparticles, in the GW\napproximation in a number of dielectrics including diamond. We find that the\nresults are quite close to a simple \"Fermi-liquid\" estimation using the\nelectronic density of diamond. We propose that a quite efficient mechanism\ncould be the excitation of plasmons by high energy electrons, followed by the\nrelaxation of plasmons into individual e-h pairs."
    },
    {
        "anchor": "Strain-Engineered Widely-Tunable Perfect Absorption Angle in Black\n  Phosphorus from First-Principles: Using the density functional theory of electronic structure, we compute the\nanisotropic dielectric response of bulk black phosphorus subject to strain.\nEmploying the obtained permittivity tensor, we solve Maxwell's equations and\nstudy the electromagnetic response of a layered structure comprising a film of\nblack phosphorus stacked on a metallic substrate. Our results reveal that a\nsmall compressive or tensile strain, $\\sim 4\\%$, exerted either perpendicular\nor in the plane to the black phosphorus growth direction, efficiently controls\nthe epsilon-near-zero response, and allows a perfect absorption tuning from\nlow-angle of the incident beam $\\theta=0^\\circ$ to high values $\\theta\\approx\n90^\\circ$ while switching the energy flow direction. Incorporating a spatially\ninhomogeneous strain model, we also find that for certain thicknesses of the\nblack phosphorus, near-perfect absorption can be achieved through controlled\nvariations of the in-plane strain. These findings can serve as guidelines for\ndesigning largely tunable perfect electromagnetic wave absorber devices.",
        "positive": "Exciton-Dominated Core-Level Absorption Spectra of Hybrid\n  Organic-Inorganic Lead Halide Perovskites: In a combined theoretical and experimental work, we investigate X-ray\nAbsorption Near-Edge Structure (XANES) spectroscopy of the I $L_3$ and the Pb\n$M_5$ edges of the methylammonium lead iodide ($\\textrm{MAPbI}_3$) hybrid\ninorganic-organic perovskite and its binary phase $\\textrm{PbI}_2$. The\nabsorption onsets are dominated by bound excitons with sizable binding energies\nof a few hundred meV and pronounced anisotropy. The spectra of both materials\nexhibit remarkable similarities, suggesting that the fingerprints of core\nexcitations in $\\textrm{MAPbI}_3$ are essentially given by its inorganic\ncomponent, with negligible influence from the organic groups. The theoretical\nanalysis complementing experimental observations provides the conceptual\ninsights required for a full characterization of this complex material."
    },
    {
        "anchor": "Ten-nanometer surface intrusions in room temperature silicon: Defects ~10 nm in size, with number densities ~10^{10} cm^{-2}, form\nspontaneously beneath ion-milled, etched, or HF-dipped silicon surfaces\nexamined in our Ti-ion getter-pumped transmission electron microscope (TEM)\nafter exposure to air. They appear as weakly-strained non-crystalline\nintrusions into silicon bulk, that show up best in the TEM under conditions of\nstrong edge or bend contrast. If ambient air exposure is <10 minutes, defect\nnucleation and growth can be monitored {\\em in situ}. Possible mechanisms of\nformation are discussed.",
        "positive": "Enhancement of electron hot spot relaxation in photoexcited plasmonic\n  structures by thermal diffusion: We demonstrate that in confined plasmonic metal structures subject to\nultra-fast laser excitation electron thermal diffusion can provide relaxation\nfaster than the energy transfer to the lattice. This relaxation occurs due to\nexcitation of nanometer-sized hot spots in the confined structure and the\nsensitivity of its optical parameters to the perturbation in these regions.\nBoth factors become essential when the plasmonic resonance condition is met for\nboth excitation and detection. A pump-probe experiment on plasmonic gold\nlattices shows sub-picosecond relaxation with the characteristic times\nwell-described by a two-temperature model. The results suggest that dynamical\noptical response in plasmonic structures can be tuned by selection of the\nstructural geometry as well as the choice of wavelength and polarization of the\nexcitation and detection light."
    },
    {
        "anchor": "Pt-Decorated PdCo@Pd/C Core-Shell Nanoparticles with Enhanced Stability\n  and Electrocatalytic Activity for Oxygen Reduction Reaction: A simple method for the preparation of PdCo@Pd core-shell nanoparticles\nsupported on carbon has been developed using an adsorbate-induced surface\nsegregation effect. The stability and electrocatalytic activity for the oxygen\nreduction of PdCo@Pd nanoparticles was enhanced by a small amount of Pt,\ndeposited via a spontaneous displacement reaction. The facile method described\nherein is suitable for large-scale lower cost production and significantly\nlowers the Pt loading and thus cost. The as-prepared PdCo@Pd and Pd-decorated\nPdCo@Pd nanocatalysts have higher methanol-tolerance for the ORR when compared\nto Pt/C, and are promising cathode catalysts for fuel cell applications.",
        "positive": "Dislocation impediment by the grain boundaries in polycrystals: Thermodynamic dislocation theory incorporating dislocation impediment by the\ngrain boundaries is developed to analyze the shear test of polycrystals. With a\nsmall set of physics based material parameters, we are able to simulate the\nstress-strain curves for the load and its reversal, which are consistent with\nthe experimental curves of Thuillier and Manach [2009]. Representative\ndistributions of plastic slip under load and its reversal are presented, and\ntheir evolution explains the extended length of the transition stage during\nload reversal."
    },
    {
        "anchor": "A substitutional quantum defect in WS$_2$ discovered by high-throughput\n  computational screening and fabricated by site-selective STM manipulation: Point defects in two-dimensional materials are of key interest for quantum\ninformation science. However, the space of possible defects is immense, making\nthe identification of high-performance quantum defects extremely challenging.\nHere, we perform high-throughput (HT) first-principles computational screening\nto search for promising quantum defects within WS$_2$, which present localized\nlevels in the band gap that can lead to bright optical transitions in the\nvisible or telecom regime. Our computed database spans more than 700 charged\ndefects formed through substitution on the tungsten or sulfur site. We found\nthat sulfur substitutions enable the most promising quantum defects. We\ncomputationally identify the neutral cobalt substitution to sulfur (Co$_{\\rm\nS}^{0}$) as very promising and fabricate it with scanning tunneling microscopy\n(STM). The Co$_{\\rm S}^{0}$ electronic structure measured by STM agrees with\nfirst principles and showcases an attractive new quantum defect. Our work shows\nhow HT computational screening and novel defect synthesis routes can be\ncombined to design new quantum defects.",
        "positive": "Application of Machine Learning to Sporadic Experimental Data for\n  Understanding Epitaxial Strain Relaxation: Understanding epitaxial strain relaxation is one of the key challenges in\nfunctional thin films with strong structure-property relation. Herein, we\nemploy an emerging data analytics approach to quantitatively evaluate the\nunderlying relationships between critical thickness (hc) of strain relaxation\nand various physical and chemical features, despite the sporadic experimental\ndata points available. First, we have collected and refined reported hc of\nperovskite oxide thin film/substrate system to construct a consistent\nsub-dataset which captures a common trend among the varying experimental\ndetails. Then, we employ correlation analyses and feature engineering to find\nthe most relevant feature set which include Poisson's ratio and lattice\nmismatch. With the insight offered by correlation analyses and feature\nengineering, machine learning (ML) models have been trained to deduce a decent\naccuracy, which has been further validated experimentally. the demonstrated\nframework is expected to be efficiently extended to the other classes of thin\nfilms in understanding hc."
    },
    {
        "anchor": "Experimental study of negative photoconductivity in n-PbTe(Ga) epitaxial\n  films: We report on low-temperature photoconductivity (PC) in n-PbTe(Ga) epitaxial\nfilms prepared by the hot-wall technique on <111>-BaF_2 substrates. Variation\nof the substrate temperature allowed us to change the resistivity of the films\nfrom 10^8 down to 10_{-2} Ohm x cm at 4.2 K. The resistivity reduction is\nassociated with a slight excess of Ga concentration, disturbing the Fermi level\npinning within the energy gap of n-PbTe(Ga). PC has been measured under\ncontinuous and pulse illumination in the temperature range 4.2-300 K. For films\nof low resistivity, the photoresponse is composed of negative and positive\nparts. Recombination processes for both effects are characterized by\nnonexponential kinetics depending on the illumination pulse duration and\nintensity. Analysis of the PC transient proves that the negative\nphotoconductivity cannot be explained in terms of nonequilibrium charge\ncarriers spatial separation of due to band modulation. Experimental results are\ninterpreted assuming the mixed valence of Ga in lead telluride and the\nformation of centers with a negative correlation energy. Specifics of the PC\nprocess is determined by the energy levels attributed to donor Ga III, acceptor\nGa I, and neutral Ga II states with respect to the crystal surrounding. The\nenergy level corresponding to the metastable state Ga II is supposed to occur\nabove the conduction band bottom, providing fast recombination rates for the\nnegative PC. The superposition of negative and positive PC is considered to be\ndependent on the ratio of the densities of states corresponding to the donor\nand acceptor impurity centers.",
        "positive": "Dominant two-dimensional electron-phonon interactions in the bulk Dirac\n  semimetal Na3Bi: Bulk Dirac semimetals (DSMs) exhibit unconventional transport properties and\nphase transitions due to their peculiar low-energy band structure. Yet the\nelectronic interactions governing nonequilibrium phenomena in DSMs are not\nfully understood. Here we show that electron-phonon (e-ph) interactions in a\nprototypical bulk DSM, Na3Bi, are predominantly two-dimensional (2D). Our\nfirst-principles calculations discover a 2D optical phonon with strong e-ph\ninteractions associated with in-plane vibrations of Na atoms. We show that this\n2D mode governs e-ph scattering and charge transport in Na3Bi, and induces a\ndynamical phase transition to a Weyl semimetal. Our work advances quantitative\nanalysis of electron interactions in topological semimetals and reveals\ndominant low-dimensional interactions in bulk quantum materials."
    },
    {
        "anchor": "SIMPRE: Installation and User Manual: This is the installation and used manual of SIMPRE 1.1, a fortran77 code that\ncan implement different effective electrostatic models based on point charges\naround a rare earth ion. The program calculates the full set of crystal field\nparameters, Stark energy levels and spin wave functions, as well as magnetic\nproperties. The package has already been successfully applied to several\nmononuclear systems with single-molecule magnetic behavior. The determination\nof effective point charge parameters in these studies facilitates its\napplication to new systems. SIMPRE was presented in DOI:10.1002/jcc.23341, and\nSIMPRE 1.1, an updated version that follows the prevailing Crystal Field\nconventions was presented in DOI:10.1002/jcc.23699.",
        "positive": "Free-standing cubic gauche nitrogen stable at 760 K under ambient\n  pressure: Cubic gauche nitrogen (cg-N) has received wide attention due to its high\nenergy density and environmental friendliness. However, existing synthesis\nmethods for cg-N predominantly rely on the high-pressure techniques, or the\nutilization of nanoconfined effects using highly toxic and sensitive sodium\nazide as precursor, which significantly restrict the practical application of\ncg-N as high energy density materials (HDEM). Here, based on the\nfirst-principles simulations, we find that the adsorption of potassium on the\ncg-N surface exhibits superior stabilization compared to sodium. Then, we chose\nthe safer potassium azide as raw material for synthesizing cg-N. Through\nplasma-enhanced chemical vapor deposition treatment, the free-standing cg-N was\nsuccessfully synthesized without the need of high-pressure and nanoconfined\neffects. Importantly, it demonstrates excellent thermal stability up to 760 K,\nand then a rapid and intense thermal decomposition occurs, exhibiting typical\nbehaviors of HDEM thermal decomposition. Our work has significantly promoted\nthe practical application of cg-N as HDEM."
    },
    {
        "anchor": "Magnetoelectric properties of the multiferroic CuCrO$_2$ studied by\n  means of ab initio calculations and Monte Carlo simulations: Motivated by the discovery of multiferroicity in the geometrically frustrated\ntriangular antiferromagnet CuCrO$_2$ below its N\\'eel temperature $T_N$, we\ninvestigate its magnetic and ferroelectric properties using ab initio\ncalculations and Monte Carlo simulations. Exchange interactions up to the third\nnearest neighbors in the $ab$ plane, inter-layer interaction and single ion\nanisotropy constants in CuCrO$_2$ are estimated by series of density functional\ntheory calculations. In particular, our results evidence a hard axis along the\n[110] direction due to the lattice distortion that takes place along this\ndirection below $T_N$. Our Monte Carlo simulations indicate that the system\npossesses a N\\'eel temperature $T_N\\approx27$ K very close to the ones reported\nexperimentally ($T_N = 24-26$ K). Also we show that the ground state is a\nproper-screw magnetic configuration with an incommensurate propagation vector\npointing along the [110] direction. Moreover, our work reports the emergence of\nspin helicity below $T_N$ which leads to ferroelectricity in the extended\ninverse Dzyaloshinskii-Moriya model. We confirm the electric control of spin\nhelicity by simulating $P$-$E$ hysteresis loops at various temperatures.",
        "positive": "Spin-resolved second-order correlation energy of the two-dimensional\n  uniform electron gas: For the two-dimensional electron gas, the exact high-density limit of the\ncorrelation energy is evaluated here numerically for all values of the spin\npolarization. The result is spin-resolved into $\\uparrow\\uparrow$,\n$\\uparrow\\downarrow$, and $\\downarrow\\downarrow$ contributions and parametrized\nanalytically. Interaction-strength interpolation yields a simple model (LSD)\nfor the correlation energy at finite densities."
    },
    {
        "anchor": "Finite element method calculations of ZnO nanowires for nanogenerators: The bending of a nonconducting piezoelectric ZnO nanowire is simulated by\nfinite element method calculations. The top part is bent by a lateral force,\nwhich could be applied by an atomic force microscope (AFM) tip. The generated\nelectrical potential is 0.3 V. This relatively high signal is, however,\ndifficult to measure, due to the low capacitance of the ZnO nanowire (4x10^{-5}\npF) as compared to the capacitance of most preamplifiers (5 pF). A further\nproblem arises from the semiconducting properties of experimentally fabricated\nZnO nanowires which causes the disappearance of the voltage signal within\npicoseconds.",
        "positive": "Hybrid single-pair charge-2 Weyl semimetals: Intuitively, the dispersion characteristics of Weyl nodes with opposite\ncharges in single-pair charge-2 Weyl semimetals are the same, quadratic or\nlinear. We theoretically predicted that single-pair hybrid charge-2 Weyl\nsemimetals (the nodes with opposite charges show quadratic Weyl and linear\ncharge-2 Dirac characteristics, respectively) can be protected by specific\nnonsymmorphic symmetries in spinless systems. Moreover, the symmetries force\nthe pair of Weyl points locate at the center and corners of the first Brillouin\nzone (FBZ), respectively. Consequently, nontrivial surface states run through\nthe entire FBZ of the system fascinating for future experimental detection and\ndevice applications. The hybrid phase is further verified with the help of\nfirst-principles calculations for the phonon states in realistic material of\nNa$_2$Zn$_2$O$_3$. The new phase will not only broaden the understanding of the\nWeyl semimetals, but also provide an interesting platform to investigate the\ninteraction between the two types of Weyl fermions with different dispersions."
    },
    {
        "anchor": "Nonaffine lattice dynamics with the Ewald method reveals strongly\n  nonaffine elasticity of \u03b1-quartz: A lattice dynamical formalism based on nonaffine response theory is derived\nfor non-centrosymmetric crystals, accounting for long-range interatomic\ninteractions using the Ewald method. The framework takes equilibrated static\nconfigurations as input to compute the elastic constants in excellent agreement\nwith both experimental data and calculations under strain. Besides this\nmethodological improvement, which enables faster evaluation of elastic\nconstants without the need of explicitly simulating the deformation process,\nthe framework provides insights into the nonaffine contribution to the elastic\nconstants of {\\alpha}-quartz. It turns out that, due to the non-centrosymmetric\nlattice structure, the nonaffine (softening) correction to the elastic\nconstants is very large, such that the overall elastic constants are at least\n3-4 times smaller than the affine Born-Huang estimat",
        "positive": "Lower current-driven exchange switching threshold in noncollinear\n  magnetic junctions under high spin injection: Current-induced switching is considered in a magnetic junction. The junction\nincludes pinned and free ferromagnetic layers which work in the regime of the\nhigh spin injection. It is shown that in such a regime the exchange\nmagnetization reversal threshold can be lowered up to two times when the axes\nof the layers are noncollinear."
    },
    {
        "anchor": "Electrochemical characterization of a Fe-based shape memory alloy in an\n  alkaline medium and the behaviour in aggressive conditions: A Fe-17Mn-6Si-19Cr-4Ni-1(V,C) shape memory steel (SMS) was characterised\nelectrochemically in its unstrained and pre-strained conditions. The work\nfocused on analysing the passive films generated in alkaline conditions, and on\nthe behaviour of those passive samples in various Cl/OH ratios. The passive\nfilms were developed by cyclic voltammetry and their characterisation was\nperformed by electrochemical impedance spectroscopy (EIS) and X-ray\nphotoelectron spectroscopy (XPS); these tests were also carried out in 304 L\nstainless steel specimens for comparison purposes. The results indicated that\nthe film characteristics (thickness and composition) were similar in all the\nsamples, although higher corrosion resistance was observed in the 304 L due to\nthe higher Cr content. In addition, the behaviour of the passive samples in\naggressive conditions was assessed by potentiodynamic measurements. The results\nstated that the shape memory steels were more sensitive than the stainless\nsteel to the aggressive conditions, especially when the alloy was pre-strained.\nIt was also observed that the SMS exhibited a characteristic corrosion\nmorphology localized at the grain boundaries.",
        "positive": "Formation of Mn2+ in La2/3Ca1/3MnO3 Thin Films due to Air Exposure: We report on the chemical stability of La2/3Ca1/3MnO3 thin films. X-ray\nabsorption spectroscopy at the Mn L-edge and O K-edge makes evident deviations\nfrom the nominally expected (2/3-1/3) Mn3+/Mn4+ ratio after the growth of thin\nfilms on LaAlO3 substrates. As-grown thin films, exhibiting Curie temperature,\nTC, well below that of the LCMO bulk material, develop an unexpected Mn2+\ncontribution after a few days of air exposure which increases with time.\nMoreover, a reduction of the saturation magnetization, MS, is also detected.\nThe similarity of the results obtained by electron yield and fluorescence yield\ndemonstrates that the location of the Mn valence anomalies are not confined to\na narrow surface region of the film but can extend throughout the film\nthickness in case of granular films. High temperature annealing not only\nimproves the magnetic and transport properties of such as-grown films but also\nrecovers the expected 2/3-1/3 Mn3+/Mn4+ ratio, which thereafter is stable to\nair exposure. Similar results on La2/3Ca1/3MnO3 films grown on SrTiO3 and\nNdGaO3 substrates demonstrate that there is no direct relation between the\nobserved Mn valence instability and the strain state of the films due to their\nlattice mismatch with the substrate. A mechanism for the formation of Mn2+ ions\nformation is discussed."
    },
    {
        "anchor": "High Throughput Screening of Ternary Nitrides with Convolutional Neural\n  Networks: The development of new materials is a core aspect of advancement in synthesis\nand application for industry. There is a vast number of possible chemical\npermutations of the basic elements that can be explored to synthesize materials\nthat possess attractive catalytic, mechanical and electrical properties that\nmay not be easily accessible to traditional experimental methods for various\nreasons, including cost and time considerations. Nitrides, as examples, require\nvery stringent and precise conditions to successfully synthesize making their\nexperimental exploration very slow. In this paper, we employ the use of machine\nlearning algorithms to predict the bulk properties of Ternary Metal Nitrides\n(TMN), specifically their bulk modulus which is correlated with the hardness of\nthe material. We were able to develop a consistent model with encouraging\naccuracy, that was able to predict the bulk moduli of materials that previously\ndid not have computed values. The model was trained on $10^3$ ternary materials\nwith known elastic properties and defined structures, and was able to predict\nthe bulk modulus of $\\thickapprox 1,000$ Ternary Metal Nitrides (TMNs) to\n$\\thickapprox 80\\%$ accuracy. This approach is orders of magnitude faster than\nthe traditional computational approaches like density functional theory\n(DFT)\\cite{dft-paper} which makes exploratory identification of materials with\npromising properties fast. We propose that such models be used to select\ninteresting candidates for high throughput computation from first principles.",
        "positive": "Verification of Short-Range Order and Its Impact on the Properties of\n  the CrCoNi Medium Entropy Alloy: Traditional metallic alloys are mixtures of elements where the atoms of\nminority species tend to distribute randomly if they are below their solubility\nlimit, or lead to the formation of secondary phases if they are above it.\nRecently, the concept of medium/high entropy alloys (MEA/HEA) has expanded this\nview, as these materials are single-phase solid solutions of generally\nequiatomic mixtures of metallic elements that have been shown to display\nenhanced mechanical properties. However, the question has remained as to how\nrandom these solid solutions actually are, with the influence of chemical\nshort-range order (SRO) suggested in computational simulations but not seen\nexperimentally. Here we report the first direct observation of SRO in the\nCrCoNi MEA using high resolution and energy-filtered transmission electron\nmicroscopy. Increasing amounts of SRO give rise to both higher stacking fault\nenergy and hardness. These discoveries suggest that the degree of chemical\nordering at the nanometer scale can be tailored through thermomechanical\nprocessing, providing a new avenue for tuning the mechanical properties of\nMEA/HEAs."
    },
    {
        "anchor": "Defects and persistent luminescence in Eu-doped SrAl$_2$O$_4$: We investigate native point defects and rare-earth (co)dopants in\nSrAl$_2$O$_4$ using hybrid density-functional defect calculations. Europium\n(Eu) and dysprosium (Dy) are found to be mixed valence and energetically most\nfavorable at the Sr lattice sites. However, unlike Eu where both Eu$^{2+}$ and\nEu$^{3+}$ can be realized in synthesis, Dy is stable predominantly as\nDy$^{3+}$, and the divalent Dy$^{2+}$ may only be photogenerated under\nirradiation. On the basis of an analysis of Eu-related band-defect (including\ncharge-transfer) and interconfigurational $5d$-$4f$ optical transitions, we\nassign the characteristic broad blue (445 nm) and green (520 nm) emission bands\nin Eu$^{2+}$-doped SrAl$_2$O$_4$ to the $4f^65d^1$ $\\rightarrow$ $4f^7$\ntransition in Eu$^{2+}$ incorporated at the Sr1 and Sr2 sites, respectively.\nStrontium interstitials (not oxygen vacancies, in contrast to what is commonly\nbelieved) and Dy$_{\\rm Sr}$ can act as efficient electron traps for\nroom-temperature persistent luminescence. This work calls for a re-assessment\nof certain assumptions regarding specific carrier trapping centers made in all\nmechanisms previously proposed for the persistent luminescence in Eu- and\n(Eu,Dy)-doped SrAl$_2$O$_4$. It also serves as a methodological template for\nthe understanding and design of rare-earth doped phosphors.",
        "positive": "Skyrmions in CeFeB Amorphous Nanodisks: Rare earth Fe B permanent magnets are usually used because of their excellent\nmagnetic performance at room temperature. The high price of these elements\npushes some researchers to find new alternatives. From rare earth elements\ncerium (Ce) is considered as the most abundant and cheap, therefore, the\ninterest was focused to study the properties of alloys based on this element in\nrecent years. In this work, we investigate the magnetization behavior of CeFeB\nnanodisks in presence of Dzyaloshinskii Moriya interaction. We show that\ntopological structures, Neel skyrmions, in particular, could be nucleated\nspontaneously in this kind of system. We also study skyrmions behavior in the\npresence of finite temperature. We demonstrate that CeFeB nanodisks could host\nmagnetic skyrmions at room temperature."
    },
    {
        "anchor": "Revisiting the crystal structure of the equilibrium S (Al2CuMg) phase in\n  Al-Cu-Mg alloys using X-ray absorption spectroscopy (XAFS): Even though, the crystal structure of the intermediate (S') and the\nequilibrium S (Al2CuMg) phase were subject of many investigations by using\nmostly imaging or diffraction techniques, the results remain still\ncontroversial. In this study, we used X-ray absorption spectroscopy (XAFS) to\nverify the correct structure considering the well-known models reported by\nPerlitz & Westgren (PW), Mondolfo, Radmilovic & Kilaas and Yan et al. The\nstructure was confirmed by direct comparison to simulated XAFS spectra using\nthe software tool FDMNES. Our results support the widely accepted PW model as\nthe correct structure while other models do not match our observations.",
        "positive": "Electric field and tip geometry effects on dielectrophoretic growth of\n  carbon nanotube nanofibrils on scanning probes: Single-wall carbon nanotube (SWNT) nanofibrils were assembled onto a variety\nof conductive scanning probes including atomic force microscope (AFM) tips and\nscanning tunnelling microscope (STM) needles using positive dielectrophoresis\n(DEP). The magnitude of the applied electric field was varied in the range of\n1-20 V to investigate its effect on the dimensions of the assembled SWNT\nnanofibrils. Both length and diameter grew asymptotically as voltage increased\nfrom 5 to 18 V. Below 4 V, stable attachment of SWNT nanofibrils could not be\nachieved due to the relatively weak DEP force versus Brownian motion. At\nvoltages of 20 V and higher, low quality nanofibrils resulted from\nincorporating large amounts of impurities. For intermediate voltages, optimal\nnanofibrils were achieved, though pivotal to this assembly is the wetting\nbehaviour upon tip immersion in the SWNT suspension drop. This process was\nmonitored in situ to correlate wetting angle and probe geometry (cone angles\nand tip height), revealing that probes with narrow cone angles and long shanks\nare optimal. It is proposed that this results from less wetting of the probe\napex, and therefore reduces capillary forces and especially force transients\nduring the nanofibril drawing process. Relatively rigid probes (force constant\n>= 2 N/m) exhibited no perceivable cantilever bending upon wetting and\nde-wetting, resulting in the most stable process control."
    },
    {
        "anchor": "Understanding disorder in 2D materials: the case of carbon doping of\n  Silicene: We investigate the effect of lattice disorder and local correlation effects\nin finite and periodic silicene structures caused by carbon doping using\nfirst-principles calculations. For both finite and periodic silicene\nstructures, the electronic properties carbon-doped monolayers are dramatically\nchanged by controlling the doping sites in the structures, which is related to\nthe amount of disorder introduced in the lattice and electron-electron\ncorrelation effects. By changing the position of the carbon dopants, we found\nthat a Mott-Anderson transition is achieved. Moreover, the band gap is\ndetermined by the level of lattice disorder and electronic correlation effects.\nFinally, these structures are ferromagnetic even under disorder which has\npotential applications in Si-based nanoelectronics, such as field-effect\ntransistors (FETs).",
        "positive": "The third conformer of graphane: A first principles DFT based study: We propose, on the basis of our first principles density functional based\ncalculations, a new isomer of graphane, in which the C-H bonds of a hexagon\nalternate in 3-up, 3-down fashion on either side of the sheet. This 2D puckered\nstructure called 'stirrup' has got a comparable stability with the previously\ndiscovered chair and boat conformers of graphane. The physico-chemical\nproperties of this third conformer are found to be similar to the other two\nconformers of graphane with an insulating direct band gap of 3.1 eV at the\n{\\Gamma} point. Any other alternative hydrogenation of the graphene sheet\ndisrupts its symmetric puckered geometry and turns out to be energetically less\nfavorable."
    },
    {
        "anchor": "On Site Raman Analysis of Iznik Pottery Glazes and Pigments: On site Raman analyses were performed at the Mus\\'{e}e national de\nC\\'{e}ramique, S\\`{e}vres, France, on rare Iznik (former Nicaea) pottery\nproduced from ~1480 to ~1620. A comparison is made with a series of shards. The\ntown of production of these potteries was highly disputed in the 80's and many\nquestions still remain. The potential of glaze on-site analyses as a\nclassification/datating tool is evaluated. The structure of the silicate glaze\ndoes not change with the sample (index of polymerisation ~ 0.5-0.8, indicating\na lead silicate composition; characteristic Si-O stretching mode doublet at\n\\~985 and 1030-1050 cm-1). By contrast the corresponding signature of most of\nthe \"K\\\"{u}tahya\" wares peaks at ~1070-1090 cm-1. The lowest index is measured\nfor a brilliant overglazed red bole, according to a lower temperature of\n(post)firing. The different crystalline phases identified in the glaze are\n&#61537;-quartz, haematite, spinel, cassiterite, uvarovite garnet and zircon.\nWhite colour arises from &#61537;-quartz slip in most samples studied.\nCassiterite (SnO2) opacifier is only present in some early blue-and-white\nceramics (Master of the Knots and Baba Nakkas style, ca. 1510-1530) and we do\nnot have other evidence of its intentional use as an opacifier. Intentional\naddition of tin oxide is likely for colour lightening in some red, blue and in\nclear green boles. At least two types of red glazes and two types of\nCr-containing green pigments are evidenced.",
        "positive": "Towards scanning nanostructure x-ray microscopy: We demonstrate spatial mapping of the local and nano-scale structure of thin\nfilm objects using spatially resolved PDF analysis of synchrotron x-ray\ndiffraction data. This is demonstrated in a lab-on-chip combinatorial array of\nsample spots containing catalytically interesting nanoparticles deposited from\nliquid precursors using an ink-jet liquid handling system. We present a\nsoftware implementation of the whole protocol including an approach for\nautomated data acquisition and analyis using the atomic pair distribution\nfunction (PDF) method. The protocol software can handle semi-automated data\nreduction, normalization and modelling, with user-defined recipes generating a\ncomprehensive collection of metadata and analysis results. By slicing the\ncollection using included functions it was possible to build images of the 2D\nobject containing using different quantities for contrast, allowing us to\ndetermine the spatial map relating to different aspects of the local structure\non the array."
    },
    {
        "anchor": "Hybrid System for Solar Energy Conversion with Nano-Structured\n  Electrodes: Solar energy is clean and renewable but has a low flux density. The lack of a\ncontinuous and reliable power supply reduces their average daily output. Since\nthe infrared part is not utilized to produce electricity, conventional\nphotovoltaic cells use only about half of the solar spectrum. Direct radiation\nflux is also necessary for solar Stirling engine to work efficiently. The\nhybrid system can largely overcome these problems. The design combines the\nphotovoltaic and energy storage-integrated Stirling engine or thermal field\nemission technologies in the same concentrating solar power system, providing a\ngreat potential in terms of energy production per unit area. The photovoltaic\ncells can be deposited on the concentrating solar power main mirror to allow\nthe system to collect and convert the diffuse component of the light. The\ndesign allows utilization of existing equipment, particularly a high-grade\nparabolic dish or midgrade Fresnel concentrator for rooftop installation. To\noptimize the use of solar energy, beam splitters thermally decouple the modules\nby splitting the solar spectrum into three spectral ranges and directing\nvisible, ultraviolet and infrared radiation into the photovoltaic cells,\ngate/Cs-filled gap and cavity-type solar receiver, respectively. A\nphoton-enhanced gate electrode creates on the cathode surface an electrostatic\nfield large enough to compensate space charge field and initiates thermal field\nemission process. In the thermal field emission cathodes with nano-structured\nsurfaces, the current density can reach values close to the field emission\nlimit. The design of the electrodes based on nano-structured emission materials\nwere experimentally explored by the co-authors. In these experiments,\nefficiency of heat-to-electricity conversion was investigated and conditions\nfor advanced nano-materials application for harvesting solar energy were found.",
        "positive": "Charge transfer effects, thermo- and photochromism in single crystal CVD\n  synthetic diamond: We report on the effects of thermal treatment and ultraviolet irradiation on\nthe point defect concentrations and optical absorption profiles of single\ncrystal CVD synthetic diamond. All thermal treatments were below 850 K, which\nis lower than the growth temperature and unlikely to result in any structural\nchange. UV-visible absorption spectroscopy measurements showed that upon\nthermal treatment (823 K), various broad absorption features diminished: an\nabsorption band at 270 nm (used to deduce neutral single substitutional\nnitrogen (NS 0) concentrations), and also two broad features centred at\napproximately 360 and 520 nm. Point defect centre concentrations as a function\nof temperature were also deduced using electron paramagnetic resonance (EPR)\nspectroscopy. Above ~500 K, we observed a decrease in the concentration of NS 0\ncentres and a concomitant increase in the negatively charged\nnitrogen-vacancy-hydrogen complex (NVH \\bar) concentration. Both transitions\nexhibited an activation energy between 0.6 and 1.2 eV, which is lower than that\nfor the NS 0 donor (~1.7 eV). Finally, it was found that illuminating samples\nwith intense short-wave ultraviolet light recovered the NS 0 concentration and\nalso the 270, 360 and 520 nm absorption features. From these results, we\npostulate a valence-band mediated charge-transfer process between NVH and\nsingle nitrogen centres with an acceptor trap depth for NVH of 0.6- 1.2 eV.\nBecause the loss of NS 0 concentration is greater than the increase in NVH \\bar\nconcentration we also suggest the presence of another unknown acceptor existing\nat a similar energy as NVH. The extent to which the colour in CVD synthetic\ndiamond is dependent on prior history is discussed."
    },
    {
        "anchor": "Accessing slip activity in high purity tin with electron backscatter\n  diffraction and measurement of slip strength: Beta-tin has been used widely as an interconnect in modern electronics. To\nimprove the understanding of the reliability of these components, we directly\nmeasure the critical resolved shear stress of individual slip systems in\nbeta-tin using micropillar compression tests at room temperature with crystal\norientations near-[100] and [001] in the loading direction within a large grain\nhigh purity tin (99.99%) sample. This activates the (110)[1-11]/2,\n(110)[1-1-1]/2, (010)[001] and (110)[001] slip systems. Analysis of the slip\ntraces and load-displacement curves enables measurement of the critical\nresolved shear stress for epsilon=10^(-4) of\ntau_(CRSS)^({110}<1-11>/2)=10.4+/-0.4 and tau_(CRSS)^({010}<001>)=3.9+/-0.3\nMPa.",
        "positive": "Molten flux growth of single crystals of quasi-1D hexagonal chalcogenide\n  BaTiS3: BaTiS3, a quasi-1D complex chalcogenide, has gathered considerable scientific\nand technological interest due to its giant optical anisotropy and electronic\nphase transitions. However, the synthesis of high-quality BaTiS3 crystals,\nparticularly those featuring crystal sizes of millimeters or larger, remains a\nchallenge. Here, we investigate the growth of BaTiS3 crystals utilizing a\nmolten salt flux of either potassium iodide, or a mixture of barium chloride\nand barium iodide. The crystals obtained through this method exhibit a\nsubstantial increase in volume compared to those synthesized via the chemical\nvapor transport method, while preserving their intrinsic optical and electronic\nproperties. Our flux growth method provides a promising route towards the\nproduction of high-quality, large-scale single crystals of BaTiS3, which will\ngreatly facilitate advanced characterizations of BaTiS3 and its practical\napplications that require large crystal dimensions. Additionally, our approach\noffers an alternative synthetic route for other emerging complex chalcogenides."
    },
    {
        "anchor": "Robust Weyl semimetallic phase in face-centered orthogonal C6 with\n  helical carbon chains: The exploration of topological phases in carbon allotropes offers a\nfascinating avenue to realize topological devices based on carbon materials.\nHere, using first-principles calculations, we propose a novel metastable carbon\nallotrope, which possesses exotically helical carbon chains bridged by\nquadrangle-rings. This unique structure with sp2-sp3 bonding networks\ncrystallizes in a noncentrosymmetric face-centered orthogonal (fco) lattice\nwith six atoms in a unit cell, thus named fco-C6. The considerable stability of\nfco-C6 is confirmed by phonon spectra, elastic constants, and ab initio\nmolecular dynamics simulations. More importantly, fco-C6 exhibits extraordinary\nelectronic properties with the minimum number of Weyl points in a time-reversal\npreserved Weyl system. The symmetry arguments reveal that the Weyl points are\nguaranteed to lie along the high-symmetry pathes and thus well separated in\nmomentum space, exhibiting the robustness of topologically protected features.\nWe investigate the topological surface states of fco-C6 projected on a\nsemi-infinite (010) surface. There are only nontrivial Fermi arcs across the\nFermi surface, which facilitates their measurements in experiments and further\napplications in carbon allotropes.",
        "positive": "High-frequency dielectric spectroscopy of batio3 core - silica shell\n  nanocomposites: Problem of interdiffusion: Three types of BaTiO3 core - amorphous nano-shell composite ceramics were\nprocessed from the same core-shell powder by standard sintering, spark-plasma\nsintering and two-step sintering techniques and characterized by XRD, HRSEM and\nbroad-band dielectric spectroscopy in the frequency range 10^3 - 10^13 Hz\nincluding the THz and IR range. The samples differed by porosity and by the\namount of interdiffusion from the cores to shells, in correlation with their\nincreasing porosity. The dielectric spectra were also calculated using suitable\nmodels based on effective medium approximation. The measurements revealed a\nstrong dielectric dispersion below the THz range, which cannot be explained by\nthe modeling, and whose strength was in correlation with the degree of\ninterdiffusion. We assigned it to an effect of the interdiffusion layers,\ngiving rise to a strong interfacial polarization. It appears that the\nhigh-frequency dielectric spectroscopy is an extremely sensitive tool for\ndetection of any gradient layers and sample inhomogeneities even in dielectric\nmaterials with negligible conductivity."
    },
    {
        "anchor": "Tailoring magnetic and hyperthermia properties of biphase iron oxide\n  nanocubes through post-annealing: Tailoring the magnetic properties of iron oxide nanosystems is essential to\nexpand their biomedical applications. In this study, the 34 nm iron oxide\nnanocubes with two phases consisting of Fe3O4 and alpha-Fe2O3 were annealed for\n2 hours in the presence of O2, N2, He, and Ar to tune the respective phase\nvolume fractions and control the magnetic properties. X-ray diffraction and\nmagnetic measurements were carried out post-treatment to evaluate the changes\nof the treated samples compared to the as-prepared, which showed an enhancement\nof the alpha-Fe2O3 phase in the samples annealed with O2, while the others\nindicated Fe3O4 enhancement. Furthermore, the latter samples indicated\nenhancements in the crystallinity and saturation magnetization while coercivity\nenhancement was most significant in the samples annealed with O2, resulting in\nthe highest specific absorption rates (up to 1000 W/g) in all the applied\nfields of 800, 600, and 400 Oe in agar during magnetic hyperthermia\nmeasurements. The general enhancement in the specific absorption rate\npost-annealing underscores the importance of the annealing atmosphere in the\nenhancement of the magnetic and structural properties of nanostructures.",
        "positive": "Modelling Localisation and Spatial Scaling of Constitutive Behaviour: a\n  Kinematically Enriched Continuum Approach: It is well known that classical constitutive models fail to capture the\npost-peak material behaviour, due to localisation of deformation. In such cases\nthe concept of Representative Volume Element (RVE) on which classical continuum\nmodels rest ceases to exist and hence the smearing out of local inhomogeneities\nover the whole RVE is no longer correct. This paper presents a new approach to\ncapturing localised failure in quasi-brittle materials, focusing on the\nkinematic enrichment of the constitutive model to describe correctly the\nbehaviour of a volume element with an embedded localisation band. The resulting\nmodels possess an intrinsic length scale which in this case is the width of the\nembedded localisation band. The behaviour therefore scales with both the width\nof the localisation band and the size of the volume on which the model is\ndefined. As a consequence, size effects are automatically captured in addition\nto the model capability in capturing behaviour at the scale of the localisation\nzone."
    },
    {
        "anchor": "Electronic, vibrational and transport properties of pnictogen\n  substituted ternary skutterudites: First principles calculations are used to investigate electronic band\nstructure and vibrational spectra of pnictogen substituted ternary\nskutterudites. We compare the results with the prototypical binary composition\nCoSb$_3$ to identify the effects of substitutions on the Sb site, and evaluate\nthe potential of ternary skutterudites for thermoelectric applications.\nElectronic transport coefficients are computed within the Boltzmann transport\nformalism assuming a constant relaxation time, using a new methodology based on\nmaximally localized Wannier function interpolation. Our results point to a\nlarge sensitivity of the electronic transport coefficients to carrier\nconcentration and to scattering mechanisms associated with the enhanced\npolarity. The ionic character of the bonds is used to explain the detrimental\neffect on the thermoelectric properties.",
        "positive": "GW method with the self-consistent Sternheimer equation: We propose a novel approach to quasiparticle GW calculations which does not\nrequire the computation of unoccupied electronic states. In our approach the\nscreened Coulomb interaction is evaluated by solving self-consistent\nlinear-response Sternheimer equations, and the noninteracting Green's function\nis evaluated by solving inhomogeneous linear systems. The frequency-dependence\nof the screened Coulomb interaction is explicitly taken into account. In order\nto avoid the singularities of the screened Coulomb interaction the calculations\nare performed along the imaginary axis, and the results are analytically\ncontinued to the real axis through Pade' approximants. As a proof of concept we\nimplemented the proposed methodology within the empirical pseudopotential\nformalism and we validated our implementation using silicon as a test case. We\nexamine the advantages and limitations of our method and describe promising\nfuture directions."
    },
    {
        "anchor": "Ferroelectricity in (K@C$_{60}$)$_n$: A theoretical analysis of the ground state of long-chain (K@C$_{60}$)$_n$ is\npresented. Within mean field theory, a ferroelectric ground state is found to\nbe stable because of the pseudo-Jahn-Teller mixing of the b$_{1u}$ and the\nb$_{2g}$ band with a zone-center optical phonon involving the displacement of\nthe endohedral K^+ ions. A phase diagram for this model is derived in the\nnarrow bandwidth regime.",
        "positive": "Using high multipolar orders to reconstruct the sound velocity in\n  piezoelectrics from lattice dynamics: Information over the phonon band structure is crucial to predicting many\nthermodynamic properties of materials, such as thermal transport coefficients.\nHighly accurate phonon dispersion curves can be, in principle, calculated in\nthe framework of density-functional perturbation theory (DFPT). However,\nwell-established techniques can run into trouble (or even catastrophically\nfail) in the case of piezoelectric materials, where the acoustic branches\nhardly reproduce the physically correct sound velocity. Here we identify the\nculprit in the higher-order multipolar interactions between atoms, and\ndemonstrate an effective procedure that fixes the aforementioned issue. Our\nstrategy drastically improves the predictive power of perturbative\nlattice-dynamical calculations in piezoelectric crystals, and is directly\nimplementable for high-throughput generation of materials databases."
    },
    {
        "anchor": "Topological Materials: Weyl Semimetals: Topological insulators and topological semimetals are both new classes of\nquantum materials, which are characterized by surface states induced by the\ntopology of the bulk band structure. Topological Dirac or Weyl semimetals show\nlinear dispersion round nodes, termed the Dirac or Weyl points, as the\nthree-dimensional analogue of graphene. We review the basic concepts and\ncompare these topological states of matter from the materials perspective with\na special focus on Weyl semimetals. The TaAs family is the ideal materials\nclass to introduce the signatures of Weyl points in a pedagogical way, from\nFermi arcs to the chiral magneto-transport properties, followed by the hunting\nfor the type-II Weyl semimetals in WTe2, MoTe2 and related compounds. Many\nmaterials are members of big families and topological properties can be tuned.\nAs one example, we introduce the multifuntional topological materials, Heusler\ncompounds, in which both topological insulators and magnetic Weyl semimetals\ncan be found. Instead of a comprehensive review, this article is expected to\nserve as a helpful introduction and summary by taking a snapshot of the quickly\nexpanding field.",
        "positive": "Sensitive SQUID magnetometry for studying nano-magnetism: The superconducting quantum interference device (SQUID) magnetometer is one\nof the most sensitive experimental techniques to magnetically characterize\nsamples with high sensitivity. Here we present a detailed discussion of\npossible artifacts and pitfalls characteristic for commercial SQUID\nmagnetometers. This includes intrinsic artifacts which stem from the inherent\ndesign of the magnetometer as well as potential issues due to the user. We\nprovide some guidelines how to avoid and correct these, which is of particular\nimportance when the proper magnetization of nano-scale objects shall be\nestablished in cases where its response is dwarfed by that of the substrate it\ncomes with, a situation frequently found in the field of nano-magnetism."
    },
    {
        "anchor": "Response of the lattice across the filling-controlled Mott\n  metal-insulator transition of a rare earth titanate: The lattice response of a prototype Mott insulator, SmTiO3, to hole doping is\ninvestigated with atomic-scale spatial resolution. SmTiO3 films are doped with\nSr on the Sm site with concentrations that span the insulating and metallic\nsides of the filling-controlled Mott metal-insulator transition (MIT). The\nGdFeO3-type distortions are investigated using an atomic resolution scanning\ntransmission electron microscopy technique that can resolve small lattice\ndistortions with picometer precision. We show that these distortions are\ngradually and uniformly reduced as the Sr concentration is increased without\nany phase separation. Significant distortions persist into the metallic state.\nThe results present a new picture of the physics of this prototype\nfilling-controlled MIT, which is discussed.",
        "positive": "Relation between Effective Conductivity and Susceptibility of Two --\n  Component Rhombic Checkerboard: The heterogeneity of composite leads to the extra charge concentration at the\nboundaries of different phases that results essentially nonzero effective\nelectric susceptability. The relation between tensors of effective electric\nsusceptability $\\hat\\chi_{ef}$ and effective conductivity $\\hat\\sigma_{ef}$ of\nthe infinite two--dimensional two--component regular composite with rhombic\ncells structure has been established. The degrees of electric field singularity\nat corner points of cells are found by constructing the integral equation for\nthe effective conductivity problem. The limits of weak and strong contrast of\npartial conductivities $\\sigma_1,\\sigma_2$ are considered. The results are\nvalid for thin films and cylindrical samples."
    },
    {
        "anchor": "Magnetic monopole and string excitations in a two-dimensional spin ice: We study the magnetic excitations of a square lattice spin-ice recently\nproduced in an artificial form, as an array of nanoscale magnets. Our analysis,\nbased upon the dipolar interaction between the nanomagnetic islands, correctly\nreproduces the ground-state observed experimentally. In addition, we find\nmagnetic monopole-like excitations effectively interacting by means of the\nusual Coulombic plus a linear confining potential, the latter being related to\na string-like excitation binding the monopoles pairs, what indicates that the\nfractionalization of magnetic dipoles may not be so easy in two dimensions.\nThese findings contrast this material with the three-dimensional analogue,\nwhere such monopoles experience only the Coulombic interaction. We discuss,\nhowever, two entropic effects that affect the monopole interactions: firstly,\nthe string configurational entropy may loose the string tension and then, free\nmagnetic monopoles should also be found in lower dimensional spin ices;\nsecondly, in contrast to the string configurational entropy, an entropically\ndriven Coulomb force, which increases with temperature, has the opposite effect\nof confining the magnetic defects.",
        "positive": "Magnon contribution to the magnetoresistance of iron nanowires deposited\n  using pulsed electrodeposition: Iron nanowires with a square cross section are grown by pulsed\nelectrodeposition within a newly developed nanochannel template that allows for\neasy characterization. Measurements of the magnetoresistance as a function of\nmagnetic field and temperature are performed within a large parameter window\nallowing for the investigation of the magnonic contribution to the\nmagnetoresistance of electrodeposited iron nanowires. Values for the\ntemperature dependent magnon stiffness D(T) are extracted."
    },
    {
        "anchor": "Embedding for bulk systems using localized atomic orbitals: We present an embedding approach for semiconductors and insulators based on\nor- bital rotations in the space of occupied Kohn-Sham orbitals. We have\nimplemented our approach in the popular VASP software package. We demonstrate\nits power for defect structures in silicon and polaron formation in titania,\ntwo challenging cases for conventional Kohn-Sham density functional theory.",
        "positive": "Toward the computational prediction of muon sites and interaction\n  parameters: The rapid developments of computational quantum chemistry methods and\nsupercomputing facilities motivate the renewed interest in the analysis of the\nmuon/electron interactions in $\\mu$SR experiments with \\emph{ab initio}\napproaches. Modern simulation methods seem to be able to provide the answers to\nthe frequently asked questions of many $\\mu$SR experiments: where is the muon?\nIs it a passive probe? What are the interaction parameters governing the\nmuon-sample interaction? In this review we describe some of the approaches used\nto provide quantitative estimations of the aforementioned quantities and we\nprovide the reader with a short discussion on the current developments in this\nfield."
    },
    {
        "anchor": "Delta Machine Learning for Predicting Dielectric Properties and Raman\n  Spectra: Raman spectroscopy is an important characterization tool with diverse\napplications in many areas of research. We propose a machine learning method\nfor predicting polarizabilities with the goal of providing Raman spectra from\nmolecular dynamics trajectories at reduced computational cost. A\nlinear-response model is used as a first step and symmetry-adapted machine\nlearning is employed for the higher-order contributions as a second step. We\ninvestigate the performance of the approach for several systems including\nmolecules and extended solids. The method can reduce training set sizes\nrequired for accurate dielectric properties and Raman spectra in comparison to\na single-step machine learning approach.",
        "positive": "Auger recombination and carrier multiplication in embedded silicon and\n  germanium nanocrystals: For Si and Ge nanocrystals (NCs) embedded in wide band-gap matrices, Auger\nrecombination (AR) and carrier multiplication (CM) lifetimes are computed\nexactly in a three-dimensional real space grid using empirical pseudopotential\nwave functions. Our results in support of recent experimental data offer new\npredictions. We extract simple Auger constants valid for NCs. We show that both\nSi and Ge NCs can benefit from photovoltaic efficiency improvement via CM due\nto the fact that under an optical excitation exceeding twice the band gap\nenergy, the electrons gain lion's share from the total excess energy and can\ncause a CM. We predict that CM becomes especially efficient for hot electrons\nwith an excess energy of about 1 eV above the CM threshold."
    },
    {
        "anchor": "A self-assembled periodic nanoporous framework in aqueous solutions of\n  the DNA tetramer GCCG: The collective behavior of the shortest DNA oligomers in high concentration\naqueous solutions is an unexplored frontier of DNA science and technology. Here\nwe broaden the realm of DNA nanoscience by demonstrating that single-component\naqueous solutions of the DNA 4-base oligomer GCCG can spontaneously organize\ninto three-dimensional (3D) periodic mesoscale frameworks. This oligomer can\nform B-type double helices by Watson-Crick (WC) pairing, into tiled\nbrickwork-like duplex strands, which arrange into mutually parallel arrays and\nform the nematic and columnar liquid crystal phases, as is typical for long WC\nchains. However, at DNA concentrations above 400mg/mL, these solutions nucleate\nand grow an additional mesoscale framework phase, comprising a periodic network\non a three dimensional body-centered cubic (BCC) lattice. This lattice is an\narray of nodes (valence-8, each formed by a pair of quadruplexes of GCCG\nterminal Gs), connected with a separation of 6.6 nm by struts (6-GCCG-long WC\nduplexes). This 3D-ordered DNA framework is of low density (DNA volume fraction\n~0.2), but, due to its 3D crystal structure, is osmotically incompressible over\nits phase range. Atomistic simulations confirm the stability of such\nstructures, which promise to form the basis of novel families of simply and\ninexpensively made nanoscale frameworks for templating and selection\napplications.",
        "positive": "Phase separation in hydrogen-helium mixtures at Mbar pressures: The properties of hydrogen-helium mixtures at Mbar pressures and intermediate\ntemperatures (4000 to 10000 K) are calculated with first-principles molecular\ndynamics simulations. We determine the equation of state as a function of\ndensity, temperature, and composition and, using thermodynamic integration, we\nestimate the Gibbs free energy of mixing, thereby determining the temperature,\nat a given pressure, when helium becomes insoluble in dense metallic hydrogen.\nThese results are directly relevant to models of the interior structure and\nevolution of Jovian planets. We find that the temperatures for the demixing of\nhelium and hydrogen are sufficiently high to cross the planetary adiabat of\nSaturn at pressures around 5 Mbar; helium is partially miscible throughout a\nsignificant portion of the interior of Saturn, and to a lesser extent in\nJupiter."
    },
    {
        "anchor": "Effect of spin glass frustration on exchange bias in NiMn/CoFeB bilayers: Exchange bias in ferromagnetic/antiferromagnetic systems can be explained in\nterms of various interfacial phenomena. Among these spin glass frustration can\naffect the magnetic properties in exchange bias systems. Here we have studied a\nNiMn/CoFeB exchange bias system in which spin glass frustration seems to play a\ncrucial role. In order to account the effect of spin glass frustration on\nmagnetic properties, we have performed the temperature and cooling field\ndependence of exchange bias. We have observed the decrease of exchange bias\nfield (HEB) with cooling field (HFC) whereas there is not significant effect on\ncoercive field (HC). Exponential decay of HEB and HC is found in these exchange\nbias systems. Further, training effect measurements have been performed to\nstudy the spin relaxation mechanism. We have fitted the training effect data\nwith frozen and rotatable spin relaxation model. We have investigated the ratio\nof relaxation rate of interfacial rotatable and frozen spins in this study. The\ntraining effect data are also fitted with various other models. Further, we\nobserved the shifting of peak temperature towards higher temperature with\nfrequency from the ac susceptibility data.",
        "positive": "Comparative Analysis of Tight-Binding models for Transition Metal\n  Dichalcogenides: We provide a comprehensive analysis of the prominent tight-binding (TB)\nmodels for transition metal dichalcogenides (TMDs) available in the literature.\nWe inspect the construction of these TB models, discuss their parameterization\nused and conduct a thorough comparison of their effectiveness in capturing\nimportant electronic properties. Based on these insights, we propose a novel TB\nmodel for TMDs designed for enhanced computational efficiency. Utilizing\n$MoS_2$ as a representative case, we explain why specific models offer a more\naccurate description. Our primary aim is to assist researchers in choosing the\nmost appropriate TB model for their calculations on TMDs."
    },
    {
        "anchor": "Frustrated network of indirect exchange paths between tetrahedrally\n  coordinated Co in Ba2CoO4: We present a detailed study of the electronic and magnetic interactions of\nBa2CoO4, structurally very uncommon because of the isolated CoO4 distorted\ntetrahedral coordination. We show the presence of Co(d)-O(p) hybridized states\ncharacterized by spin polarized oxygen atoms, with their magnetic moments\nparallel to that on Co. The calculated isotropic exchange interaction\nparameters, which include the contributions from ligand spins, demonstrate the\npresence of a 3D network of magnetic couplings, that are partially frustrated\nin the identified magnetic ground state. Our results indicate that the dominant\nindirect exchange mechanism responsible for this ground state is mediated by O\natoms along the Co-O...O-Co path.",
        "positive": "Enhanced interface perpendicular magnetic anisotropy in Ta|CoFeB|MgO\n  using nitrogen doped Ta underlayers: We show that the magnetic characteristics of Ta|CoFeB|MgO magnetic\nheterostructures are strongly influenced by doping the Ta underlayer with\nnitrogen. In particular, the saturation magnetization drops upon doping the Ta\nunderlayer, suggesting that the doped underlayer acts as a boron diffusion\nbarrier. In addition, the thickness of the magnetic dead layer decreases with\nincreasing nitrogen doping. Surprisingly, the interface magnetic anisotropy\nincreases to ~1.8 erg/cm2 when an optimum amount of nitrogen is introduced into\nthe Ta underlayer. These results show that nitrogen doped Ta serves as a good\nunderlayer for Spintronics applications including magnetic tunnel junctions and\ndomain wall devices."
    },
    {
        "anchor": "Phonon quarticity induced by changes in phonon-tracked hybridization\n  during lattice expansion and its stabilization of rutile TiO$_2$: Although the rutile structure of TiO$_2$ is stable at high temperatures, the\nconventional quasiharmonic approximation predicts that several acoustic phonons\ndecrease anomalously to zero frequency with thermal expansion, incorrectly\npredicting a structural collapse at temperatures well below 1000\\,K. Inelastic\nneutron scattering was used to measure the temperature dependence of the phonon\ndensity of states (DOS) of rutile TiO$_2$ from 300 to 1373\\,K. Surprisingly,\nthese anomalous acoustic phonons were found to increase in frequency with\ntemperature. First-principles calculations showed that with lattice expansion,\nthe potentials for the anomalous acoustic phonons transform from quadratic to\nquartic, stabilizing the rutile phase at high temperatures. In these modes, the\nvibrational displacements of adjacent Ti and O atoms cause variations in\nhybridization of $3d$ electrons of Ti and $2p$ electrons of O atoms. With\nthermal expansion, the energy variation in this \"phonon-tracked hybridization\"\nflattens the bottom of the interatomic potential well between Ti and O atoms,\nand induces a quarticity in the phonon potential.",
        "positive": "Interstitial-Boron Solution Strengthened WB$_{3+x}$: By means of variable-composition evolutionary algorithm coupled with density\nfunctional theory and in combination with aberration-corrected high-resolution\ntransmission electron microscopy experiments, we have studied and characterized\nthe composition, structure and hardness properties of WB$_{3+x}$ ($x$ $<$ 0.5).\nWe provide robust evidence for the occurrence of stoichiometric WB$_3$ and\nnon-stoichiometric WB$_{3+x}$ both crystallizing in the metastable $hP$16\n($P6_3/mmc$) structure. No signs for the formation of the highly debated WB$_4$\n(both $hP$20 and $hP$10) phases were found. Our results rationalize the\nseemingly contradictory high-pressure experimental findings and suggest that\nthe interstitial boron atom is located in the tungsten layer and vertically\ninterconnect with four boron atoms, thus forming a typical three-center boron\nnet with the upper and lower boron layers in a three-dimensional covalent\nnetwork, which thereby strengthen the hardness."
    },
    {
        "anchor": "A tight-binding investigation of biaxial strain induced topological\n  phase transition in GeCH$_3$: We propose a tight-binding (TB) model, that includes spin-orbit coupling\n(SOC), to describe the electronic properties of methyl-substituted germanane\n(GeCH$_3$). This model gives an electronic spectrum in agreement with first\nprinciple results close to the Fermi level. Using the $\\mathbb{Z}_2$ formalism,\nwe show that a topological phase transition from a normal insulator (NI) to a\nquantum spin Hall (QSH) phase occurs at 11.6\\% biaxial tensile strain. The\nsensitivity of the electronic properties of this system on strain, in\nparticular its transition to the topological insulating phase, makes it very\nattractive for applications in strain sensors and other microelectronic\napplications.",
        "positive": "A method of calculating bandstructure in real-space with application to\n  all-electron and full potential: We introduce a practical and efficient approach for calculating the\nall-electron full potential bandstructure in real space, employing a finite\nelement basis. As an alternative to the k-space method, the method involves the\nself-consistent solution of the Kohn-Sham equation within a larger finite\nsystem that encloses the unit-cell. It is based on the fact that the net\npotential of the unit-cell converges at a certain radius point. Bandstructure\nresults are then obtained by performing non-self-consistent calculations in the\nBrillouin zone. Numerous numerical experiments demonstrate that the obtained\nvalence and conduction bands are in excellent agreement with the\npseudopotential k-space method. Moreover, we successfully observe the band\nbending of core electrons."
    },
    {
        "anchor": "ZnS/Diamond Composite Coatings for Infrared Transmission Applications\n  Formed by the Aerosol Deposition Method: The deposition of nano-crystalline ZnS/diamond composite protective coatings\non silicon, sapphire, and ZnS substrates, as a preliminary step to coating\ninfrared transparent ZnS substrates from powder mixtures by the aerosol\ndeposition method is presented. Advantages of the aerosol deposition method\ninclude the ability to form dense, nanocrystalline films up to hundreds of\nmicrons thick at room temperature and at a high deposition rate on a variety of\nsubstrates. Deposition is achieved by creating a pressure gradient that\naccelerates micrometer-scale particles in an aerosol to high velocity.\n  Upon impact with the target substrate the particles fracture and embed.\nContinued deposition forms the thick compacted film. Deposition from an\naerosolized mixture of ZnS and diamond powders onto all targets results in\nlinear trend from apparent sputter erosion of the substrate at 100% diamond to\nformation of a film with increasing fractions of ZnS. The crossover from\nabrasion to film formation on sapphire occurs above about 50% ZnS and a mixture\nof 90% ZnS and 10% diamond forms a well-adhered film of about 0.7 \\mu m\nthickness at a rate of 0.14 \\mu m/min. Resulting films are characterized by\nscanning electron microscopy, profilometry, infrared transmission spectroscopy,\nand x-ray photoemission spectroscopy. These initial films mark progress toward\nthe future goal of coating ZnS substrates for abrasion resistance.",
        "positive": "Polarization description of successive ferroelectric switching in hafnia: Intertwined ionic conduction and ferroelectric (FE) switching in HfO2 lead to\nextensive focuses. To describe its fundamental phenomena, we present a\nfree-energy model describing the potential of ferroelectrics with successive FE\nswitching paths, and extend the domain model of ionic conduction to\nferroelectric domains. Associate theoretical analyses and first-principles\ncalculations suggest a nesting-domain pattern with opposite piezoelectric loops\nduring the nucleation-and-growth process in displacive FE-HfO2. A collective\noxygen ion conduction mechanism is also proposed with a field-dependent ionic\nconductivity following the Merz's law. We conclude that the ionic\nconductibility is concomitant with the ferroelectricity in HfO2, and it may\nprovide a new venue for pursuing low temperature fast oxide-ion conductors and\nartificial synapses."
    },
    {
        "anchor": "Heat transfer by mobile low-frequency phonons and \"localized\" modes in\n  cryocrystal solutions: The temperature and volume dependences of the thermal conductivity of solid\nKr(1-x)Xe(x)solution are analyzed within the model in which heat is transferred\nby mobile low-frequency phonons; above the phonon mobility edge this is done by\n\"localized\" modes migrating randomly from site to site. The phonon mobility\nedge (w0)is determined from the condition that the phonon mean -free path\nrestricted by Umklapp processes and point defects scattering cannot be smaller\nthan one-half the phonon wavelength. The Bridgman coefficient is the weighted -\nmean over these modes whose volume dependences differ widely. It is shown that\nthe amount of heat transferred by the \"localized\" modes above 100 K is quite\nlarge even in pure Kr and it increases with rising temperature and impurity\nconcentration.",
        "positive": "Signatures of novel magnon-phonon coupling in frustrated double\n  perovskite square lattices: Low-dimensional frustrated magnetic square networks feature a variety of\nunconventional phases with novel emergent excitations. Often these excitations\nare intertwined and manifest into intriguing phenomena, an area that has\nremained largely unexplored in square-lattice systems, especially, double\nperovskites (A2BB'O6). In this study, we explore these interactions between the\nfundamental excitations such as phonons and magnons in square-lattice\nSr2CuTeO6, Sr2CuWO6, and Ba2CuWO6 isostructural double perovskites that exhibit\nboth short-ranged (TS) as well as long-ranged Neel antiferromagnetic (TN)\ntransitions. Our Raman measurements at variable temperatures reveal an\nintriguing broad peak (identified as 2-magnon (2M)) surviving beyond TS for\nW-based compositions contrary to the Te-based system, suggesting a key role of\ndiamagnetic B'-site cation on their magnetism. The thermal response of 2M\nintriguingly shows signatures of correlation with phonons and control over\ntheir anharmonicity, depicting magnon-phonon interaction. Further, a few\nphonons exhibit anomalies across the magnetic transitions implying the presence\nof spin-phonon coupling. In particular, the phonon modes at ~ 194 cm-1 of\nSr2CuTeO6 and ~ 168 cm-1 of Sr2CuWO6, that show a strong correlation with the\n2M, exhibit the strongest spin-phonon coupling suggesting their roles in\nmediating magnon-phonon interactions in these systems."
    },
    {
        "anchor": "Hydrogen Release from Sodium Alanate Observed by Time-resolved Neutron\n  Backscattering: Innermolecular motion in Na3AlH6 gives rise to a Lorentzian spectrum with a\nwavenumber-independent width of about 1 micro-eV at 180 deg C, which is\nprobably due to rotation of AlH6 tetrahedra. There is no such quasielastic line\nin NaAlH4 or NaH. Based on this finding, time-resolved measurements on the\nneutron backscattering spectrometer SPHERES were used to monitor the\ndecomposition kinetics of sodium alanate, NaAlH4 to Na3AlH6 to NaH. Both\nreaction steps were found to be accelerated by autocatalysis, most likely at\nthe surfaces of Na3AlH6 and NaH crystallites.",
        "positive": "TaCo$_{2}$Te$_{2}$: An air-stable, magnetic van der Waals material with\n  high mobility: Van der Waals (vdW) materials are an indispensable part of functional device\ntechnology due to their versatile physical properties and ease of exfoliating\nto the low-dimensional limit. Among all the compounds investigated so far, the\nsearch for magnetic vdW materials has intensified in recent years, fueled by\nthe realization of magnetism in two dimensions (2D). However, metallic magnetic\nvdW systems are still uncommon. In addition, they rarely host high-mobility\ncharge carriers, which is an essential requirement for high-speed electronic\napplications. Another shortcoming of 2D magnets is that they are highly air\nsensitive. Using chemical reasoning, we introduce TaCo2Te2 as an air-stable,\nhigh-mobility, magnetic vdW material. It has a layered structure, which\nconsists of Peierls distorted Co chains and a large vdW gap between the layers.\nWe find that the bulk crystals can be easily exfoliated and the obtained thin\nflakes are robust to ambient conditions after four months of monitoring using\nan optical microscope. We also observe signatures of canted antiferromagntic\nbehavior at low-temperature. TaCo2Te2 shows a metallic character and a large,\nnon-saturating, anisotropic magnetoresistance. Furthermore, our Hall data and\nquantum oscillation measurements reveal the presence of both electron- and\nhole-type carriers and their high mobility."
    },
    {
        "anchor": "1/f Noise in Thin Films of Topological Insulator Materials: We report results of investigation of the low-frequency excess noise in\ndevice channels made from topological insulators - a new class of materials\nwith a bulk insulating gap and conducting surface states. The thin-film bismuth\nselenide samples were prepared by the \"graphene-like\" mechanical exfoliation\nfrom bulk crystals. The fabricated four-contact devices had linear current -\nvoltage characteristics in the low-bias regime. The current fluctuations had\nthe noise spectral density proportional to 1/f for the frequency f below 10\nkHz. The noise spectral density followed the quadratic dependence on the drain\n- source current. The obtained data is important for planning transport\nexperiments with topological insulators. We suggest that achieving the pure\ntopological insulator phase with the current conduction through the \"protected\"\nsurface states can lead to noise reduction via suppression of certain\nscattering mechanisms.",
        "positive": "Chemically Tailoring Semiconducting Two-Dimensional Transition Metal\n  Dichalcogenides and Black Phosphorus: Two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDCs)\nand black phosphorus (BP) have beneficial electronic, optical, and physical\nproperties at the few-layer limit. As atomically thin materials, 2D TMDCs and\nBP are highly sensitive to their environment and chemical modification,\nresulting in a strong dependence of their properties on substrate effects,\nintrinsic defects, and extrinsic adsorbates. Furthermore, the integration of 2D\nsemiconductors into electronic and optoelectronic devices introduces unique\nchallenges at metal-semiconductor and dielectric-semiconductor interfaces.\nHere, we review emerging efforts to understand and exploit chemical effects to\ninfluence the properties of 2D TMDCs and BP. In some cases, surface chemistry\nleads to significant degradation, thus necessitating the development of robust\npassivation schemes. On the other hand, appropriately designed chemical\nmodification can be used to beneficially tailor electronic properties, such as\ncontrolling doping levels and charge carrier concentrations. Overall, chemical\nmethods allow substantial tunability of the properties of 2D TMDCs and BP,\nthereby enabling significant future opportunities to optimize performance for\ndevice applications."
    },
    {
        "anchor": "Fast Scanning Probe Microscopy via Machine Learning: Non-rectangular\n  scans with compressed sensing and Gaussian process optimization: Fast scanning probe microscopy enabled via machine learning allows for a\nbroad range of nanoscale, temporally resolved physics to be uncovered. However,\nsuch examples for functional imaging are few in number. Here, using\npiezoresponse force microscopy (PFM) as a model application, we demonstrate a\nfactor of 5.8 improvement in imaging rate using a combination of sparse spiral\nscanning with compressive sensing and Gaussian processing reconstruction. It is\nfound that even extremely sparse scans offer strong reconstructions with less\nthan 6 % error for Gaussian processing reconstructions. Further, we analyze the\nerror associated with each reconstructive technique per reconstruction\niteration finding the error is similar past approximately 15 iterations, while\nat initial iterations Gaussian processing outperforms compressive sensing. This\nstudy highlights the capabilities of reconstruction techniques when applied to\nsparse data, particularly sparse spiral PFM scans, with broad applications in\nscanning probe and electron microscopies.",
        "positive": "Self-assembly of cylinder forming diblock copolymers on modulated\n  substrates: a simulation study: Self-consistent field theory (SCFT) and strong segregation theory (SST) are\nused to explore the parameter space governing the self-assembly of cylinder\nforming block copolymers (BCPs) on a modulated substrate. The stability of\nin-plane cylinders aligning parallel or perpendicular to substrate corrugation\nis investigated for different barrier height and spacing for a weakly\npreferential substrate. Within the conditions of our simulations, the results\nindicate that cylinder alignment orthogonal to substrate undulation is promoted\nat low barrier height when substrate is preferential to minority block,\nindependent of barrier spacing. Commensurability is shown to play a limited\nrole in the assembly of orthogonal meshes. Parallel alignment is readily\nachieved at larger barrier height, near condition of commensuration between\nbarrier spacing and polymer equilibrium period. This is particularly true when\nsubstrate is attractive to majority block. The interplay between barrier shape\nand substrate affinity can be utilized in nanotechnology application such as\nmesh creation, density multiplication, and 3D BCP morphologies."
    },
    {
        "anchor": "Realization of multiple topological states and topological phase\n  transitions in (4,0) carbon nanotube derivatives: Exploring various topological states (TS) and topological phase transitions\n(TPT) has attracted great attention in condensed matter physics. However, so\nfar, there is rarely a typical material system that can be used as a platform\nto study the TS and TPT as the system transforms from one-dimensional (1D)\nnanoribbons to two-dimensional (2D) sheet then to three-dimensional (3D) bulk.\nHere, we first propose that some typical TS in 1D, 2D, and 3D systems can be\nrealized in a tight-binding (TB) model. Following the TB model and further\nbased on first-principles electronic structure calculations, we demonstrate\nthat the structurally stable (4,0) carbon nanotube derivatives are an ideal\nplatform to explore the semiconductor/nodal-point semimetal states in 1D\nnanoribbons [1D-(4,0)-C16H4 and 1D-(4,0)-C32H4], nodal-ring semimetal state in\n2D sheet [2D-(4,0)-C16], and nodal-cage semimetal state in 3D bulk\n[3D-(4,0)-C16]. Furthermore, we calculate the characteristic band structures\nand the edge/surface states of 2D-(4,0)-C16 and 3D-(4,0)-C16 to confirm their\nnontrivial topological properties. Our work not only provides new excellent 2D\nand 3D members for the topological carbon material family, but also serves as\nan ideal template for the study of TS and TPT with the change of system\ndimension.",
        "positive": "Electron properties of fluorinated single-layer graphene transistors: We have fabricated transistor structures using fluorinated single-layer\ngraphene flakes and studied their electronic properties at different\ntemperatures. Compared with pristine graphene, fluorinated graphene has very\nlarge and strongly temperature dependent resistance in the electro-neutrality\nregion. We show that fluorination creates a mobility gap in graphene's spectrum\nwhere electron transport takes place via localised electron states."
    },
    {
        "anchor": "Phase Stability and Raman/IR Signatures of Ni-Doped MoS$_2$ from\n  Density-Functional Theory Studies: Ni-doped MoS$_2$ is a layered material with useful tribological,\noptoelectronic, and catalytic properties. Experiment and theory on doped\nMoS$_2$ has focused mostly on monolayers or finite particles: theoretical\nstudies of bulk Ni-doped MoS$_2$ are lacking and the mechanisms by which Ni\nalters bulk properties are largely unsettled. We use density functional theory\ncalculations to determine the structure, mechanical properties, electronic\nproperties, and formation energies of bulk Ni-doped 2H-MoS$_2$ as a function of\ndoping concentration. We find four meta-stable structures: Mo or S\nsubstitution, and tetrahedral (t-) or octahedral (o-) intercalation. We compute\nphase diagrams as a function of chemical potential to guide experimental\nsynthesis. A convex hull analysis shows that t-intercalation (favored over\no-intercalation) is quite stable against phase segregation and in comparison\nwith other compounds containing Ni, Mo, and S; the doping formation energy is\naround 0.1 meV/atom. Intercalation forms strong interlayer covalent bonds and\ndoes not increase the $c$-parameter. Ni-doping creates new states in the\nelectronic density of states in MoS$_2$ and shifts the Fermi level, which are\nof interest for tuning the electronic and optical properties. We calculate the\ninfrared and Raman spectra and find new peaks and shifts in existing peaks that\nare unique to each dopant site, and therefore may be used to identify the site\nexperimentally, which has been a challenge to do conclusively.",
        "positive": "Efficient NMR measurement and data analysis supported by the Bayesian\n  inference : The case of the heavy fermion compound YbCo2Zn20: We propose a data-driven technique to infer microscopic physical quantities\nfrom nuclear magnetic resonance(NMR) spectra, in which the data size and\nquality required for the Bayesian inference are investigated. The $^{59}$Co-NMR\nmeasurement of YbCo$_2$Zn$_{20}$ single crystal generates complex spectra with\n28 peaks. By exploiting the site symmetry in the crystal structure, the\nisotropic Knight shift $K_{iso}$ and nuclear quadrupole resonance(NQR)\nfrequency $\\nu_Q$ were estimated to be $K_{iso} = 0.7822 \\pm 0.0090 \\%$, $\\nu_Q\n= 2.008 \\pm 0.016$ MHz ( T = 20 K, H $\\simeq$ 10.2 T) by analyzing only 30 data\npoints from one spectrum. The estimation of $\\nu_Q$ is consistent with the\nprecise value obtained in the NQR experiment. Our method can significantly\nreduce the measurement time and the computational cost of data analysis in NMR\nexperiments."
    },
    {
        "anchor": "Theoretical Study of Carbon Clusters in Silicon Carbide Nanowires: Using first-principles methods we performed a theoretical study of carbon\nclusters in silicon carbide nanowires. We examined small clusters with carbon\ninterstitials and antisites in hydrogen-passivated SiC nanowires growth along\nthe [100] and [111] directions. The formation energies of these clusters were\ncalculated as a function of the carbon concentration. We verified that the\nenergetic stability of the carbon defects in SiC nanowires depends strongly on\nthe composition of the nanowire surface: the energetically most favorable\nconfiguration in carbon-coated [100] SiC nanowire is not expected to occur in\nsilicon-coated [100] SiC nanowire. The binding energies of some aggregates were\nalso obtained, and they indicate that the formation of carbon clusters in SiC\nnanowires is energetically favored.",
        "positive": "Structural and electronic properties of rare earth chromites: A\n  computational and experimental study: In this work, the structural, optical, and electronic properties of\nrare-earth perovskites of the general formula RCrO3, where R represents the\nrare-earth Gd, Tb, Dy, Ho, Er, and Tm, have been studied in detail. These\ncompounds were synthesized through a facile citrate route. X-ray diffraction,\nRaman spectroscopy, and UV-Vis spectroscopy were used to reveal the structural\nevolutions in RCrO3. The lattice parameter, Cr3+-O2--Cr3+ bond angle, and CrO6\noctahedral distortions were found to strongly depend on the ionic radii of the\nrare-earth element. First-principles calculations based on density-functional\ntheory within the generalized gradient approximation (GGA) of Perdew- Burke-\nErnzerhof (PBE) and strongly constrained-and-appropriately normed (SCAN)\nmeta-GGA were also employed to calculate the structural and electronic\nproperties of RCrO3. The ground-state energy, lattice constants, electronic\nstructure, and density of states (DOS) of RCrO3 were calculated. These provide\nsome insights into the electronic characteristics of the series of RCrO3\ncompounds. The calculated values of lattice parameters and band gaps with\nHubbard U correction (SCAN+U) agree well with values measured experimentally\nand show more accuracy in predicting the ground-state crystal structure and\nband structure compared to PBE+U approximation. The band gap of RCrO3 is found\nto be independent of the ionic radii of the element R from both experiments and\ncalculations"
    },
    {
        "anchor": "Chemical Aspects of the Antiferromagnetic Topological Insulator\n  MnBi$_{2}$Te$_{4}$: Crystal growth of MnBi$_{2}$Te$_{4}$ has delivered the first experimental\ncorroboration of the 3D antiferromagnetic topological insulator state. Our\npresent results confirm that the synthesis of MnBi$_{2}$Te$_{4}$ can be\nscaled-up and strengthen it as a promising experimental platform for studies of\na crossover between magnetic ordering and non-trivial topology. High-quality\nsingle crystals of MnBi$_{2}$Te$_{4}$ are grown by slow cooling within a narrow\nrange between the melting points of Bi$_{2}$Te$_{3}$ (586 {\\deg}C) and\nMnBi$_{2}$Te$_{4}$ (600 {\\deg}C). Single crystal X-ray diffraction and electron\nmicroscopy reveal ubiquitous antisite defects in both cation sites and,\npossibly, Mn vacancies. Powders of MnBi$_{2}$Te$_{4}$ can be obtained at\nsubsolidus temperatures, and a complementary thermochemical study establishes a\nlimited high-temperature range of phase stability. Nevertheless, quenched\npowders are stable at room temperature and exhibit long-range antiferromagnetic\nordering below 24 K. The expected Mn(II) out-of-plane magnetic state is\nconfirmed by the magnetization, X-ray photoemission, X-ray absorption and\nlinear dichroism data. MnBi$_{2}$Te$_{4}$ exhibits a metallic type of\nresistivity in the range 4.5-300 K. The compound is an n-type conductor that\nreaches a thermoelectric figure of merit up to ZT = 0.17. Angle-resolved\nphotoemission experiments provide evidence for a surface state forming a gapped\nDirac cone.",
        "positive": "Defect-induced exchange bias in a single SrRuO3 layer: Exchange bias stems from the interaction between different magnetic phases\nand therefore it generally occurs in magnetic multilayers. Here we present a\nlarge exchange bias in a single SrRuO3 layer induced by helium ion irradiation.\nWhen the fluence increases, the induced defects not only suppress the\nmagnetization and the Curie temperature, but also drive a metal-insulator\ntransition at a low temperature. In particular, a large exchange bias field up\nto around 0.36 T can be created by the irradiation. This large exchange bias is\nrelated to the coexistence of different magnetic and structural phases that are\nintroduced by embedded defects. Our work demonstrates that spintronic\nproperties in complex oxides can be created and enhanced by applying ion\nirradiation."
    },
    {
        "anchor": "Combinatorial tuning of electronic structure and thermoelectric\n  properties in Co$_2$MnAl$_{1-x}$Si$_x$ Weyl semimetals: A tuning of Fermi level (E$_F$) near Weyl points is one of the promising\napproaches to realize large anomalous Nernst effect (ANE). In this work, we\nintroduce an efficient approach to tune E$_F$ for the Co$_2$MnAl Weyl semimetal\nthrough a layer-by-layer combinatorial deposition of Co$_2$MnAl$_{1-x}$Si$_x$\n(CMAS) thin film. A single-crystalline composition-spread film with x varied\nfrom 0 to 1 was fabricated. The structural characterization reveals the\nformation of single-phase CMAS alloy throughout the composition range with a\ngradual improvement of L2$_1$ order with x similar to the co-sputtered single\nlayered film, which validates the present fabrication technique. Hard X-ray\nphotoemission spectroscopy for the CMAS composition-spread film directly\nconfirmed the rigid band-like E$_F$ shift of approximately 0.40 eV towards the\ncomposition gradient direction from x = 0 to 1. The anomalous Ettingshausen\neffect (AEE), the reciprocal of ANE, has been measured for whole x range using\na single strip along the composition gradient using the lock-in thermography\ntechnique. The similarity of the x dependence of observed AEE and ANE signals\nclearly demonstrates that the AEE measurement on the composition spread film is\nan effective approach to investigate the composition dependence of ANE of Weyl\nsemimetal thin films and realize the highest performance without fabricating\nseveral films, which will accelerate the research for ANE-based energy\nharvesting",
        "positive": "Basis functions on the grain boundary space: Theory: With the increasing availability of experimental and computational data\nconcerning the properties and distribution of grain boundaries in\npolycrystalline materials, there is a corresponding need to efficiently and\nsystematically express functions on the grain boundary space. A grain boundary\ncan be described by the rotations applied to two grains on either side of a\nfixed boundary plane, suggesting that the grain boundary space is related to\nthe space of rotations. This observation is used to construct an orthornormal\nfunction basis, allowing effectively arbitrary functions on the grain boundary\nspace to be written as linear combinations of the basis functions. Moreover, a\nprocedure is developed to construct a smaller set of basis functions consistent\nwith the crystallographic point group symmetries, grain exchange symmetry, and\nthe null boundary singularity. Functions with the corresponding symmetries can\nbe efficiently expressed as linear combinations of the symmetrized basis\nfunctions. An example is provided that shows the efficacy of the symmetrization\nprocedure."
    },
    {
        "anchor": "The Raman fingerprint of rhombohedral graphite: Multi-layer graphene with rhombohedral stacking is a promising carbon phase\npossibly displaying correlated states like magnetism or superconductivity due\nto the occurrence of a flat surface band at the Fermi level. Recently, flakes\nof thickness up to 17 layers were tentatively attributed ABC sequences although\nthe Raman fingerprint of rhombohedral multilayer graphene is currently unknown\nand the 2D resonant Raman spectrum of Bernal graphite not understood. We\nprovide a first principles description of the 2D Raman peak in three and four\nlayers graphene (all stackings) as well as in Bernal, rhombohedral and an\nalternation of Bernal and rhombohedral graphite. We give practical\nprescriptions to identify long range sequences of ABC multi-layer graphene. Our\nwork is a prerequisite to experimental non-destructive identification and\nsynthesis of rhombohedral graphite.",
        "positive": "Dynamics of Graphene/Al Interfaces using COMB3 Potentials: This work describes the development of a third-generation charge optimized\nmany-body (COMB3) potential for Al-C and its application to the investigation\nof aluminum/graphene nanostructures. In particular, the new COMB3 potential was\nused to investigate the interactions of aluminum surfaces with pristine and\ndefective graphene sheets. Classical molecular dynamics simulations were\nperformed at temperatures of 300-900K to investigate the structural evolution\nof these interfaces. The results indicate that although the interfaces between\nAl and graphene are mostly weakly bonded, aluminum carbide can form under the\nright conditions, including the presence of vacancy defects in graphene,\nundercoordinated Al in surface regions with sharp boundaries, and at high\ntemperatures. COMB3 potentials were further used to examine a new method to\ntransfer graphene between Al surfaces as well as between Al and Cu surfaces by\ncontrolling the angle of the graphene between the two surfaces. The findings\nindicate that by controlling the peeling angles it is possible to transfer\ngraphene without any damage from the surface having greater graphene/surface\nadhesion to another surface with less adhesion."
    },
    {
        "anchor": "Crack tip kinematics reveal the cohesive zone structure in brittle\n  hydrogel fracture: When brittle hydrogels fail, several mechanisms conspire to alter the state\nof stress near the tip of a crack, and it is challenging to identify which\nmechanism is dominant. In the fracture of brittle solids, a sufficient\nfar-field stress results in the complete loss of structural strength as the\nmaterial `unzips' at the tip of a crack, where stresses are concentrated.\nDirect studies of the so-called small-scale yielding zone, where deformation is\nlarge, are sparing. Using hydrogels as a model brittle solid, we probe the\nsmall-scale yielding region with a combination of microscopy methods that\nresolve the kinematics of the deformation. A zone over which most of the energy\nis dissipated through the loss of cohesion is identified in the immediate\nsurroundings of the crack tip. With direct measurements, we determine the scale\nand structure of this zone, and identify how the specific loss mechanisms in\nthis hydrogel material might generalize for brittle material failure.",
        "positive": "Vegetable ash as raw material in the production of glasses and enamels,\n  for example the contemporary vegetable ashes from Burgundy, France: The powdery nature and high alkali content of vegetable ashes make them ideal\nraw materials to be used as modifiers of silicate compositions (glasses,\nenamels and ceramics). Their utilisation since ancient times is described in\nthe literature of the history of glasses, but studies on the analyses of their\ncomposition are still limited. We discuss here the compositions of tree and\nshrub ashes (wattle, hawthorn, oak, green oak, olive wood, elm, poplar, apple\ntree, vine shoot), of plants (carex, fern, dogwood), of cereals (wheat, maize,\nrice), threshing waste and hay, mainly harvested in Maconnais, near Taiz\\'e\n(Sa\\^one-et-Loire, France), by the potter Brother D. de Montmolin. The\ncontributions in alkali modifiers (Na2O, K2O), alkaline-earth (CaO, MgO) and in\nsilica are discussed in view of the data gathered from the literature of the\nhistory of techniques used in the production of ceramics, enamels and glasses.\nThe huge variation in composition is usually attributed to recycling and is\nquestioned by the very broad range of compositions that we obtained in the\nanalyses of the ashes."
    },
    {
        "anchor": "How to reveal metastable skyrmionic spin structures by spin-polarized\n  scanning tunneling microscopy: We predict the occurrence of metastable skyrmionic spin structures such as\nantiskyrmions and higher-order skyrmions in ultra-thin transition-metal films\nat surfaces using Monte Carlo simulations based on a spin Hamiltonian\nparametrized from density functional theory calculations. We show that such\nspin structures will appear with a similar contrast in spin-polarized scanning\ntunneling microscopy (SP-STM) images. Both skyrmions and antiskyrmions display\na circular shape for out-of-plane magnetized tips and a two-lobe butterfly\ncontrast for in-plane tips. An unambiguous distinction can be achieved by\nrotating the tip magnetization direction without requiring the information of\nall components of the magnetization.",
        "positive": "Scattering by flexural phonons in suspended graphene under back gate\n  induced strain: We have studied electron scattering by out-of-plane (flexural) phonon modes\nin doped suspended graphene and its effect on charge transport. In the\nfree-standing case (absence of strain) the flexural branch shows a quadratic\ndispersion relation, which becomes linear at long wavelength when the sample is\nunder tension due to the rotation symmetry breaking. In the non-strained case,\nscattering by flexural phonons is the main limitation to electron mobility.\nThis picture changes drastically when strains above $\\bar{u}=10^{-4}\nn(10^{12}\\,\\text{cm}^{-2})$ are considered. Here we study in particular the\ncase of back gate induced strain, and apply our theoretical findings to recent\nexperiments in suspended graphene."
    },
    {
        "anchor": "Identification and characterization of icosahedral metallic nanowires: We present and discuss an algorithm to identify and characterize the long\nicosahedral structures (staggered pentagonal nanowires with 1-5-1-5 atomic\nstructure) that appear in Molecular Dynamics simulations of metallic nanowires\nof different species subjected to stretching. The use of the algorithm allows\nthe identification of pentagonal rings forming the icosahedral structure as\nwell as the determination of its number, and the maximum length of the\npentagonal nanowire. The algorithm is tested with some ideal structures to show\nits ability to discriminate between pentagonal rings and other ring structures.\nWe applied the algorithm to Ni nanowires with temperatures ranging between 4K\nand 865K, stretched along the [100] direction. We studied statistically the\nformation of pentagonal nanowires obtaining the distributions of the maximum\nlength and number of rings as function of the temperature. The pentagonal\nnanowire maximum length distribution presents a peaked shape, with peaks locate\nat fixes distances whose separa-tion corresponds to the distance between two\nconsecutive pentagonal rings.",
        "positive": "Tailored nano-columnar La$_2$NiO$_4$ cathodes for improved electrode\n  performance: La$_2$NiO$_4$ is a very promising cathode material for intermediate and low\ntemperature solid oxide cell applications, due to its good electronic and ionic\nconductivity, together with its high oxygen exchange activity with a low\nactivation energy. Oxygen incorporation and transport in La$_2$NiO$_4$ (L2NO4)\nthin films is limited by surface reactions. Hence, tailoring the morphology is\nexpected to lead to an overall improvement of the electrode performance. We\nreport on the growth of nano-architectured La$_2$NiO$_4$ thin film electrodes\nby Pulsed Injection Metal Organic Vapour Deposition (PI-MOCVD), achieving\nvertically gapped columns with multi-fold active surface area, leading to much\nfaster oxygen exchange. This nano-columnar structure is rooted in a dense\nbottom layer serving as good electronic and ionic conduction pathway. The\nmicrostructure is tuned by modification of the growth temperature and\ncharacterised by SEM, TEM and XRD. We studied the effect of surface activity by\nelectrical conductivity relaxation measurements in fully dense and\nnano-columnar La$_2$NiO$_4$ thin films of various thicknesses grown on several\ndifferent single crystal substrates. Our results demonstrate that the increased\nsurface area, in combination with the opening of different surface\nterminations, leads to a significant enhancment of the total exchange activity\nin our films with optimized nano-architectured microstructure."
    },
    {
        "anchor": "Fine-Tuning of the Excitonic Response in Monolayer WS2 Domes via Coupled\n  Pressure and Strain Variation: We present a spectroscopic investigation into the vibrational and\noptoelectronic properties of WS2 domes in the 0-0.65 GPa range. The pressure\nevolution of the system morphology, deduced by the combined analysis of Raman\nand photoluminescence spectra, revealed a significant variation in the dome's\naspect ratio. The modification of the dome shape caused major changes in the\nmechanical properties of the system resulting in a sizable increase of the\nout-of-plane compressive strain while keeping the in-plane tensile strain\nunchanged. The variation of the strain gradients drives a non-linear behavior\nin both the exciton energy and radiative recombination intensity, interpreted\nas the consequence of a hybridization mechanism between the electronic states\nof two distinct minima in the conduction band. Our results indicate that\npressure and strain can be efficiently combined in low dimensional systems with\nunconventional morphology to obtain modulations of the electronic band\nstructure not achievable in planar crystals.",
        "positive": "Evidence of 1D behaviour of He$^4$ confined within carbon-nanotube\n  bundles: We present the first low-temperature thermodynamic investigation of the\ncontrolled physisorption of He$^{4}$ gas in carbon single-wall nanotube (SWNT)\nsamples. The vibrational specific heat measured between 100 mK and 6 K\ndemonstrates an extreme sensitivity to outgassing conditions. For bundles with\na few number of NTs the extra contribution to the specific heat, C$_{ads}$,\noriginating from adsorbed He$^{4}$ at very low density displays 1D behavior,\ntypical for He atoms localized within linear channels as grooves and\ninterstitials, for the first time evidenced. For larger bundles, C$_{ads}$\nrecovers the 2D behaviour akin to the case of He$^{4}$ films on planar\nsubstrates (grafoil)."
    },
    {
        "anchor": "Effects of s,p - d and s - p exchange interactions probed by exciton\n  magnetospectroscopy in (Ga,Mn)N: Near band-gap photoluminescence and reflectivity in magnetic field are\nemployed to determine the exchange-induced splitting of free exciton states in\nparamagnetic wurtzite Ga1-xMnxN, x < 1%, grown on sapphire substrates by\nmetal-organic vapor phase epitaxy. The band gap is found to increase with x.\nThe giant Zeeman splitting of all three excitons A, B and C is resolved,\nenabling the determination of the apparent exchange integrals N0alpha(app) =\n0.0 +/- 0.1 eV and N0beta(app) = +0.8 +/- 0.2 eV. These non-standard values and\nsigns of the s - d and p - d exchange energies are explained in terms of recent\ntheories that suggest a contribution of the electron-hole exchange to the spin\nsplitting of the conduction band and a renormalization of the free hole\nspin-splitting by a large p - d hybridization. According to these models, in\nthe limit of a strong p - d coupling, the band gap of (Ga,Mn)N increases with x\nand the order of hole spin subbands is reversed, as observed.",
        "positive": "Giant nonlinear anomalous Hall effect induced by spin-dependent band\n  structure evolution: Anomalous Hall effect (AHE) is the key transport signature unlocking\ntopological properties of magnetic materials. While AHE is usually proportional\nto the magnetization, the nonlinearity suggests the existence of complex\nmagnetic and electron orders. Nonlinear AHE includes the topological Hall\neffect (THE) that has been widely used to identify the presence of spin\nchirality in real space. But it can in principle be induced by band structure\nevolution via Berry curvatures in the reciprocal space. This effect has been\nlargely overlooked due to the intertwined mechanisms in both real and\nreciprocal spaces. Here, we observed a giant nonlinear AHE with the resistivity\nup to 383.5 uohm cm, contributing unprecedentedly 97% of the total Hall\nresponse in EuCd2As2. Moreover, it can be further enhanced by tilting the\nmagnetic field 30{\\deg} away from [001] direction, reaching a large anomalous\nHall angle up to 21%. Although it shows exactly the same double-peak feature as\nTHE, our scaling analysis and first-principles calculations reveal that the\nBerry phase is extremely sensitive to the spin canting, and nonlinear AHE is a\nconsequence of band structure evolution under the external magnetic fields.\nWhen the spins gradually tilt from the in-plane antiferromagnetic ground state\nto out-of-plane direction, band crossing and band inversion occur, introducing\na bandgap at {\\Gamma} point at a canting angle of 45{\\deg}. That contributes to\nthe enhancement of Berry curvature and consequently a large intrinsic Hall\nconductivity. Our results unequivocally reveal the sensitive dependence of band\nstructures on spin tilting process under external magnetic fields and its\npronounced influence on the transport properties, which also need to be taken\ninto consideration in other magnetic materials."
    },
    {
        "anchor": "Structural Alternation Correlated to the Conductivity Enhancement of\n  PEDOT:PSS Films by Secondary Doping: \"Secondary doping\" in\npoly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) is quite\neffective and a frequently used method for the conductivity enhancement. This\nsimple approach, the addition of co-solvents to the PEDOT:PSS solution before\nfilm fabrication, is an essential way to derive the high electrical performance\nof PEDOT:PSS, but the mechanism still remains unclear. In this study, nanoscale\nstructural changes synchronized with the conductivity enhancement via secondary\ndoping in PEDOT:PSS films were investigated. During secondary doping with\nethylene glycol near the critical dopant concentration, non-crystalized PEDOT\nmolecules uncoupled from PSS chains and then underwent nano-crystallization.\nThese structural changes might be the key driving force for conductivity\nenhancement via secondary doping.",
        "positive": "Variation of the fundamental band gap nature in curved two-dimensional\n  WS2: We report a strain-induced direct-to-indirect band gap transition in\nmechanically deformed WS2 monolayers (MLs). The necessary amount of strain is\nattained by proton irradiation of bulk WS2 and the ensuing formation of\none-ML-thick, H2-filled domes. The electronic properties of the curved MLs are\nmapped by spatially- and time-resolved micro-photoluminescence revealing the\nmechanical stress conditions that trigger the variation of the band gap\ncharacter. This general phenomenon, also observed in MoS2 and WSe2, further\nincreases our understanding of the electronic structure of transition metal\ndichalcogenide MLs and holds a great relevance for their optoelectronic\napplications."
    },
    {
        "anchor": "Efficient and Accurate Machine-Learning Interpolation of Atomic Energies\n  in Compositions with Many Species: Machine-learning potentials (MLPs) for atomistic simulations are a promising\nalternative to conventional classical potentials. Current approaches rely on\ndescriptors of the local atomic environment with dimensions that increase\nquadratically with the number of chemical species. In this article, we\ndemonstrate that such a scaling can be avoided in practice. We show that a\nmathematically simple and computationally efficient descriptor with constant\ncomplexity is sufficient to represent transition-metal oxide compositions and\nbiomolecules containing 11 chemical species with a precision of around 3\nmeV/atom. This insight removes a perceived bound on the utility of MLPs and\npaves the way to investigate the physics of previously inaccessible materials\nwith more than ten chemical species.",
        "positive": "Numerical adiabatic potentials of orthorhombic Jahn-Teller effects\n  retrieved from ultrasound attenuation experiments. Application to the SrF2:Cr\n  crystal: A methodology is worked out to retrieve the numerical values of all the main\nparameters of the six-dimensional adiabatic potential energy surface (APES) of\na polyatomic system with a quadratic T-term Jahn-Teller effect (JTE) from\nultrasound experiments. The method is based on a verified assumption that\nultrasound attenuation and speed encounter anomalies when the direction of\npropa- gation and polarization of its wave of strain coincides with the\ncharacteristic directions of symmetry breaking in the JTE. For the SrF2:Cr\ncrystal, employed as a basic example, we observed anomaly peaks in the\ntemperature dependence of attenuation of ultrasound at frequencies of 50-160\nMHz in the temperature interval of 40-60 K for the wave propagating along the\n[110] direction, for both the longitudinal and shear modes, the latter with two\npolarizations along the [001] and [110] axes, respectively. We show that these\nanomalies are due to the ultrasound relaxation by the system of non-interacting\nCr2+ JT centers with orthorhombic local distortions. The interpretation of the\nex- perimental findings is based on the T2g (eg +t2g) JTE problem including the\nlinear and quadratic terms of vibronic interactions in the Hamiltonian and the\nsame-symmetry modes reduced to one interaction mode. Combining the experimental\nresults with a theoretical analysis we show that on the complicated\nsix-dimensional APES of this system with three tetragonal, four trigonal, and\nsix orthorhombic extrema points, the latter are global minima, while the former\nare saddle points, and we estimate numerically all the main parameters of this\nsurface, including the linear and quadratic vibronic coupling constants, the\nprimary force constants, the coordinates of all the extrema points and their\nenergies, the energy barrier between the orthorhombic minima, and the tunneling\nsplitting of the ground vibrational states."
    },
    {
        "anchor": "Structural characterisation of tin fluorophosphate glasses doped with\n  Er2O3: EXAFS and confocal Raman microscopy have been used to study\n50SnF2.(20-x)SnO.30P2O5.xEr2O3 (x=0, 0.1, 0.25) glasses. EXAFS data reveal an\naverage coordination of Sn to O of 1.5 in both undoped glass and Er-doped glass\nsamples. The first coordination sphere of Er in glasses doped with Er2O3 was\nfound to have 9 F atom neighbours at an average bond length of 2.292+/-0.005\n{\\AA}, indicating that Er preferentially bonds with F. Raman spectra clearly\nshow the emergence of orthophosphate Q0 units on addition of Er2O3. The\nsaturation of Er solubility is found to be between 0.25 and 0.5 mol$\\%$ Er2O3.\nAn increase of the glass transition temperature from $\\sim$80{\\deg}C in undoped\nglass to $\\sim$87{\\deg}C in samples doped with 0.25 mol$\\%$ Er2O3 was also\nobserved. This process is accompanied by an increase in the difference between\nthe crystallisation and glass transition temperatures, which is usually\nassociated with improved thermal stability of the glass.",
        "positive": "Properties of spatial arrangement of V-type defects in irradiated\n  materials: 3D-modelling: We consider the dynamics of pattern formation in a system of point defects\nunder sustained irradiation within the framework of the rate theory. In our\nstudy we generalize the standard approach taking into account a production of\ndefects by elastic fields and a stochastic production representing internal\nmultiplicative noise. Using 3D-modelling we have shown that with the damage\nrate growth, a morphology of clusters composed of vacancies changes. The same\neffect is observed with variation in the multiplicative noise intensity.\nStationary patterns are studied by means of correlation analysis."
    },
    {
        "anchor": "Doping Concentration Modulation in Vanadium Doped Monolayer Molybdenum\n  Disulfide for Synaptic Transistors: Doping is an effective way to modify the electronic property of\ntwo-dimensional (2D) materials and endow them with new functionalities.\nHowever, wide-range control of the substitutional doping concentration with\nlarge scale uniformity remains challenging in 2D materials. Here we report\nin-situ chemical vapor deposition growth of vanadium (V) doped monolayer\nmolybdenum disulfide (MoS2) with widely tunable doping concentrations ranging\nfrom 0.3 to 13.1 at%. The key to regulate the doping concentration lies in the\nuse of appropriate V precursors with different doping abilities, which also\ngenerate a large-scale uniform doping effect. Artificial synaptic transistors\nwere fabricated by using the heavily doped MoS2 as the channel material for the\nfirst time. Synaptic potentiation, depression and repetitive learning processes\nare mimicked by the gate-tunable channel conductance change in such transistors\nwith abundant V atoms to trap/detrap electrons. This work shows a feasible\nmethod to dope monolayer 2D semiconductors and demonstrates their use in\nartificial synaptic transistors.",
        "positive": "Imaging dynamic exciton interactions and coupling in transition metal\n  dichalcogenides: Transition metal dichalcogenides (TMDs) are regarded as a possible materials\nplatform for quantum information science and related device applications. In\nTMD monolayers, the dephasing time and inhomogeneity are crucial parameters for\nany quantum information application. In TMD heterostructures, coupling strength\nand interlayer exciton lifetimes are also parameters of interest. However, many\ndemonstrations in TMDs can only be realized at specific spots on the sample,\npresenting a challenge to the scalability of these applications. Here, using\nmulti-dimensional coherent imaging spectroscopy (MDCIS), we shed light on the\nunderlying physics - including dephasing, inhomogeneity, and strain - for a\nMoSe$_2$ monolayer and identify both promising and unfavorable areas for\nquantum information applications. We furthermore apply the same technique to a\nMoSe$_2$/WSe$_2$ heterostructure. Despite the notable presence of strain and\ndielectric environment changes, coherent and incoherent coupling, as well as\ninterlayer exciton lifetimes are mostly robust across the sample. This\nuniformity is despite a significantly inhomogeneous interlayer exciton\nphotoluminescence distribution that suggests a bad sample for device\napplications. This robustness strengthens the case for TMDs as a\nnext-generation materials platform in quantum information science and beyond."
    },
    {
        "anchor": "A Perspective on the Grouping and Categorization of Nanomaterials: The development of science-based categorization strategies for regulatory\npurposes is not a simple task. It requires understanding the needs and capacity\nof a wide variety of stakeholders and should consider the potential risks and\nunintended consequences. For an evolving science area, such as\nnanotechnologies, the overall uncertainties of designing an effective\ncategorization scheme can be significant. Future nanomaterials may be far more\ncomplex and may integrate far different functionalities than modern\nnanomaterials. There is much that has been learned from our experience with\nlegacy nanomaterials and particulate substances in general. Most of the modern\nnanomaterials are not new nor dramatically different from parent or existing\nchemical substances, however there are some nuances. Applying these learnings\nto define reasonable science-based categories that consider how different\nemerging nanomaterials might be from existing known substances (while\nintegrating sound concepts as they develop) would be a pragmatic and flexible\npath forward. However, there are many barriers down this road including a need\nfor improvement and updates to chemical classification systems to improve\nhazard and risk communications, while promoting transparency and consistency.",
        "positive": "Dynamic Quantized Fracture Mechanics: A new quantum action-based theory, Dynamic Quantized Fracture Mechanics\n(DQFM), is presented that modifies continuum-based dynamic fracture mechanics.\nThe crack propagation is assumed as quantized in both space and time. The\nstatic limit case corresponds to Quantized Fracture Mechanics (QFM), that we\nhave recently developed to predict the strength of nanostructures."
    },
    {
        "anchor": "Kinetics of moisture absorption in mixtures for iron foundry: The moisture absorption in granulated materials used in foundry technologies\nis analyzed. The absorption process has a diffusive behavior mainly. A simple\nexperimental technique, in which the wet weight increment was recorded as the\nexperimental parameter and an analytic method with computing procedure to find\nthe parameters characterizing the process was used. The determination of these\nparameters by traditional methods is a very difficult task so, very refined and\nexpensive trials are needed. The fitting of the model permits to determine the\ndiffusion coefficient and the moisture concentration in the separation surface\nbetween the sample and the environment. The concentration profiles are\nestablished for different times. Finally, the possibility of occurrence of\nsuperimposed diffusive processes in some materials is analyzed and the\ndiffusion coefficient and the amount of moisture incorporated by each process\nare calculated.",
        "positive": "Assessing exchange-correlation functionals for heterogeneous catalysis\n  of nitrogen species: Increasing interest in sustainable synthesis of ammonia, nitrates, and urea\nhas led to an increase in studies of catalytic conversion between\nnitrogen-containing compounds using heterogeneous catalysts. Density functional\ntheory (DFT) is commonly employed to obtain molecular-scale insight into these\nreactions, but there have been relatively few assessments of the\nexchange-correlation functionals that are best suited for heterogeneous\ncatalysis of nitrogen compounds. Here, we assess a range of functionals ranging\nfrom the generalized gradient approximation (GGA) to the random phase\napproximation (RPA) for the formation energies of gas-phase nitrogen species,\nthe lattice constants of representative solids from several common classes of\ncatalysts (metals, oxides, and metal-organic frameworks (MOFs)), and the\nadsorption energies of a range of nitrogen-containing intermediates on these\nmaterials. The results reveal that the choice of exchange-correlation\nfunctional and van der Waals correction can have a surprisingly large effect\nand that increasing the level of theory does not always improve the accuracy\nfor nitrogen-containing compounds. This suggests that the selection of\nfunctionals should be carefully evaluated on the basis of the specific reaction\nand material being studied."
    },
    {
        "anchor": "Al doped graphene: A promising material for hydrogen storage at room\n  temperature: A promising material for hydrogen storage at room temperature-Al doped\ngraphene was proposed theoretically by using density functional theory\ncalculation. Hydrogen storage capacity of 5.13 wt% was predicted at T = 300 K\nand P = 0.1 Gpa with adsorption energy Eb = -0.260 eV/H2. This is close to the\ntarget of 6 wt% and satisfies the requirement of immobilization hydrogen with\nEb of -0.2 ~ -0.4 eV/H2 at ambient temperature and modest pressure for\ncommercial applications specified by U.S. Department of Energy. It is believed\nthat the doped Al varies the electronic structures of both C and H2. The bands\nof H2 overlapping with those of Al and C synchronously are the underlying\nmechanism of hydrogen storage capacity enhancement.",
        "positive": "Geometrically-Controlled Microscale Patterning and Epitaxial Lateral\n  Overgrowth of Nitrogen-Polar GaN: In this study we report on a novel two-step epitaxial growth technique that\nenables a significant improvement of the crystal quality of nitrogen-polar GaN.\nThe starting material is grown on 4{\\deg} vicinal sapphire substrates by metal\norganic vapour phase epitaxy, with an initial high-temperature sapphire\nnitridation to control polarity. The material is then converted into a regular\narray of hexagonal pyramids by wet-etch in a KOH solution, and subsequently\nregrown to coalesce the pyramids back into a smooth layer of improved crystal\nquality. The key points that enable this technique are the control of the array\ngeometry, obtained by exploiting the anisotropic behaviour of the wet-etch\nstep, and the use of regrowth conditions that preserve the orientation of the\npyramids' sidewalls. In contrast, growth conditions that cause an excessive\nexpansion of the residual (000-1) facets on the pyramids' tops cause the onset\nof a very rough surface morphology upon full coalescence. An X-ray diffraction\nstudy confirms the reduction of the threading dislocation density as the\nregrowth step develops. The analysis of the relative position of the 000-2 GaN\npeak with respect to the 0006 sapphire peak reveals a macroscopic tilt of the\npyramids, probably induced by the large off-axis substrate orientation. This\ntilt correlates very well with an anomalous broadening of the 000-2 diffraction\npeaks at the beginning of the regrowth step."
    },
    {
        "anchor": "$\\textit{Ab initio}$ study of phosphorus anodes for lithium and\n  sodium-ion batteries: Phosphorus has received recent attention in the context of high-capacity and\nhigh-rate anodes for lithium and sodium-ion batteries. Here, we present a first\nprinciples structure prediction study combined with NMR calculations which\ngives us insights into its lithiation/sodiation process. We report a variety of\nnew phases phases found by AIRSS and the atomic species swapping methods. Of\nparticular interest, a stable Na$_5$P$_4$-C2/m structure and locally stable\nstructures found less than 10 meV/f.u. from the convex hull, such as\nLi$_4$P$_3$-P2$_1$2$_1$2$_1$, NaP$_5$-Pnma and Na$_4$P$_3$-Cmcm. The mechanical\nstability of Na$_5$P$_4$-C2/m and Li$_4$P$_3$-P2$_1$2$_1$2$_1$ has been studied\nby first principles phonon calculations . We have calculated average voltages\nwhich suggests that black phosphorus (BP) can be considered as a safe anode in\nlithium-ion batteries due to its high lithium insertion voltage, 1.5 V;\nmoreover, BP exhibits a relatively low theoretical volume expansion compared\nwith other intercalation anodes, 216\\% ($\\Delta V/V$). We identify that\nspecific ranges in the calculated shielding can be associated with specific\nionic arrangements, results which play an important role in the interpretation\nof NMR spectroscopy experiments. Since the lithium-phosphides are found to be\ninsulating even at high lithium concentrations we show that Li-P-doped phases\nwith aluminium have electronic states at the Fermi level suggesting that using\naluminium as a dopant can improve the electrochemical performance of P anodes.",
        "positive": "Carrier density change in Colossal Magnetoresistive Pyrochlore Tl2Mn2O7: Hall resistivity and magneto-thermopower have been measured for colossal\nmagnetoresistive Tl2Mn2O7 over wide temperature and magnetic-field ranges.\nThese measurements revealed that a small number of free electron-like carriers\nis responsible for the magneto-transport properties. In contrast to perovskite\nCMR materials, the anomalous Hall coefficient is negligible even in the\nferromagnetic state due to negligibly small skew scattering. The characteristic\nfeature in Tl2Mn2O7 is that the carrier density changes with temperature and\nthe magnetic field. The carrier density increases around TC as the temperature\nis lowered or as the magnetic field is increased, which explains the CMR of\nthis material. The conduction-band-edge shift, which is caused by the strong\ns-d interaction between localized Mn moments and s-like conduction electrons,\nis a possible mechanism for the carrier density change."
    },
    {
        "anchor": "Synthesis of Epitaxial Single-Layer MoS$_2$ on Au(111): We present a method for synthesizing large area epitaxial single-layer\nMoS$_2$ on the Au(111) surface in ultrahigh vacuum. Using scanning tunneling\nmicroscopy and low energy electron diffraction, the evolution of the growth is\nfollowed from nanoscale single-layer MoS$_2$ islands to a continuous MoS$_2$\nlayer. An exceptionally good control over the MoS$_2$ coverage is maintained\nusing an approach based on cycles of Mo evaporation and sulfurization to first\nnucleate the MoS$_2$ nano-islands and then gradually increase their size.\nDuring this growth process the native herringbone reconstruction of Au(111) is\nlifted as shown by low energy electron diffraction measurements. Within these\nMoS$_2$ islands, we identify domains rotated by 60$^{\\circ}$ that lead to\natomically sharp line defects at domain boundaries. As the MoS$_2$ coverage\napproaches the limit of a complete single-layer, the formation of bilayer\nMoS$_2$ islands is initiated. Angle-resolved photoemission spectroscopy\nmeasurements of both single and bilayer MoS$_2$ samples show a dramatic change\nin their band structure around the center of the Brillouin zone. Brief exposure\nto air after removing the MoS$_2$ layer from vacuum is not found to affect its\nquality.",
        "positive": "Ultrafast nonadiabatic phonon renormalization in photoexcited\n  single-layer MoS$_2$: Comprehending nonequilibrium electron-phonon dynamics at the microscopic\nlevel and at the short time scales is one of the main goals in condensed matter\nphysics. Effective temperature models and time-dependent Boltzmann equations\nare standard techniques for exploring and understanding nonequilibrium state\nand the corresponding scattering channels. However, these methods consider only\nthe time evolution of carrier occupation function, while the self-consistent\nphonon dressing in each time instant coming from the nonequilibrium population\nis ignored, which makes them less suitable for studying ultrafast phenomena\nwhere softening of the phonon modes plays an active role. Here, we combine\nab-initio time-dependent Boltzmann equations and many-body phonon self-energy\ncalculations to investigate the full momentum- and mode-resolved nonadiabatic\nphonon renormalization picture in the MoS$_2$ monolayer under nonequilibrium\nconditions. Our results show that the nonequilibrium state of photoexcited\nMoS$_2$ is governed by multi-valley topology of valence and conduction bands\nthat brings about characteristic anisotropic electron-phonon thermalization\npaths and the corresponding phonon renormalization of strongly-coupled modes\naround high-symmetry points of the Brillouin zone. As the carrier population is\nthermalized towards its equilibrium state, we track in time the evolution of\nthe remarkable phonon anomalies induced by nonequilibrium and the overall\nenhancement of the phonon relaxation rates. This work shows potential\nguidelines to tailor the electron-phonon relaxation channels and control the\nphonon dynamics under extreme photoexcited conditions."
    },
    {
        "anchor": "First-principles study of luminescence in Eu$^{2+}$-doped inorganic\n  scintillators: Luminescence in Eu$^{2+}$ activated materials corresponds to a transition\nfrom an excited state where the lowest Eu 5$d$ level is filled with one\nelectron (often called the (Eu$^{2+}$)$^*$ state) to the ground state with\nhalf-filled 4$f$ shell with seven electrons of the same spin. We have performed\ntheoretical calculations based on Density Functional Theory to determine the\nground state band structure of Eu-doped materials as well as study the\n(Eu$^{2+}$)$^*$ excited state. Calculations were performed on Eu doped\nmaterials, experimentally known to be either scintillators or\nnon-scintillators, in order to relate theoretically calculable parameters to\nexperimentally observed properties. Applying criteria previously developed for\nCe-doped systems (A.Canning, A. Chaudhry, R. Boutchko and N.\nGr\\o{}nbech-Jensen, Phys. Rev. B Vol.83, 125115 (2011)) to new Eu-doped\nmaterials we developed a list of candidate materials for new bright Eu\nactivated scintillators. Ba$_2$CsBr$_5$:Eu is an example of a new bright\nscintillator from our candidate list that has been synthesized in\nmicrocrystalline powder form. As discussed in our previous paper on Ce-doped\nmaterials this approach was designed as a systematic high-throughput method to\naid in the discovery of new bright scintillator materials by prioritization and\ndown-selection on the large number of potential new materials.",
        "positive": "OPTIMADE, an API for exchanging materials data: The Open Databases Integration for Materials Design (OPTIMADE) consortium has\ndesigned a universal application programming interface (API) to make materials\ndatabases accessible and interoperable. We outline the first stable release of\nthe specification, v1.0, which is already supported by many leading databases\nand several software packages. We illustrate the advantages of the OPTIMADE API\nthrough worked examples on each of the public materials databases that support\nthe full API specification."
    },
    {
        "anchor": "Surface spin canting in Fe3O4 and CoFe2O4 nanoparticles probed by high\n  resolution electron energy loss spectroscopy: High resolution electron energy loss spectroscopy (HR-EELS) is utilized to\nprobe the surface spin canting in nanoparticles of two technologically\nimportant magnetic materials, i.e. Fe3O4 and CoFe2O4 (CFO). A soft experimental\ntechnique is developed that is capable of extracting EELS spectra with one\natomic plane resolution recorded in a single frame. This yields information at\ndifferent depth of the nanoparticle from the surface to the core regions with\nhigh signal to noise ratio and without beam damage. This enables comparing the\nfine structures between the surface and core regions of the nanoparticles. The\nresults confirm earlier observations of uniformly oriented spin canting\nstructure for CFO with additional information on atom site-selective spin\ncanting information. In case of Fe3O4 preferred canting orientation forming\ncore and shell structure is deduced. Unlike earlier reports based on polarized\nspin-flip neutron scattering measurement, it is possible to narrow down the\npossible canting angles for Fe3O4 (Td, Oh tilts 40{\\deg}, 40{\\deg}) and CFO\n(Td, Oh tilts 17{\\deg}, 17{\\deg}) from the experimental spectra combined with\nthe first principle based calculation considering non-collinear magnetism. In\naddition, the role of Dzyaloshinskii-Moriya interaction in stabilizing the spin\ncanting at the nanoparticle surface is discussed. The results demonstrate that\nHREELS can be a powerful technique to probe the magnetic structure in\nnano-dimensional systems and has advantages over neutron based techniques in\nterms of superior spatial resolution, site specific information and easy of\nsample preparation.",
        "positive": "Upper bound on the disordered density of sphere packing and the Kepler\n  Conjecture: The average distance of the equal hard spheres is introduced to evaluate the\ndensity of a given arrangement. The absolute smallest value is two radii\nbecause the spheres can not be closer to each other than their diameter. The\nabsolute densest arrangement of two, three and four spheres is defined, which\ngives the absolute highest density in one, two and three dimensions. The\nabsolute highest density of equal spheres in three dimensions is the\ntetrahedron formed by the centers of four spheres touching each other with\ndensity of 0.7796. The density of this tetrahedron unit can be maintained only\nlocally because the tetrahedron units can not be expanded to form a tightly\npacked arrangement in three dimensions. The maximum number of tetrahedron units\nthat one sphere is able to accommodate is twenty which corresponds to the\ndensity of 0.684. The only compatible formation of equal spheres which can be\nmixed with tetrahedron is octahedron. In order to mix the tetrahedron and\noctahedron units certain geometrical constrains must be satisfied. It is shown\nthat the only possible mixture of tetrahedrons and octahedrons units is the one\nwhich accommodates eight tetrahedron and six octahedron vertexes which is\nidentical to FCC and an alternative proof for the Kepler conjecture. It is\nsuggested that there is a density gap between the FCC density and the highest\ndensity of disordered arrangements and that the icosahedrons configuration with\nits 0.684 density represents the upper bound on the disordered arrangements."
    },
    {
        "anchor": "Spin-polarized electronic surface states of Re(0001): an ab-initio\n  investigation: We study the electronic structure of the Re(0001) surface by means of\nab-initio techniques based on the Fully Relativistic (FR) Density Functional\nTheory (DFT) and the Projector Augmented-Wave (PAW) method. We identify the\nmain surface states and resonances and study in detail their energy dispersion\nalong the main symmetry lines of the SBZ. Moreover, we discuss the effect of\nspin-orbit coupling on the energy splittings and the spin-polarization of the\nmain surface states and resonances. Whenever possible, we compare the results\nwith previously studied heavy metals surfaces. We find empty resonances,\nlocated below a gap similar to the L-gap of the (111) fcc surfaces, that have a\ndownward dispersion and cross the Fermi level, similarly to the recently\nstudied Os(0001) surface. Their spin polarization at the Fermi level is similar\nto that predicted by the Rashba model, but the usual level crossing at\n$\\bar{\\Gamma}$ is not found with our slab thickness. Moreover, for selected\nstates, we follow the spin polarization along the high symmetry lines,\ndiscussing its behavior with respect to ${\\bf k}_{\\parallel}$, the wave-vector\nparallel to the surface.",
        "positive": "Efficient quantum-chemical geometry optimization and the structure of\n  large icosahedral fullerenes: Geometry optimization is efficient using generalized Gaunt coefficients,\nwhich significantly limit the amount of cross differentiation for multi-center\nintegrals of high-angular-momentum solid-harmonic basis sets. We parameterize\nthe fully analytic formulation of density functional theory (ADFT), called the\nSlater-Roothaan method, developed in our group to give the exact geometry of\nC60 fullerene. The parametrized ADFT is subsequently used to optimize\ngeometries of most stable C240, C540, C960, C1500 and C2160 icosahedral\nfullerenes. The calculations are all electron, the orbital basis set includes d\nfunctions and the exchange-correlation-potential basis set includes f\nfunctions. The calculation of C2160 fullerene employed about 39000 basis\nfunctions and is the largest calculation reported on any isolated molecule\nto-date. The evolution of interatomic distance and atomization energy from C60\nto graphite has been investigated."
    },
    {
        "anchor": "mDCThermalC: A program for calculating thermal conductivity quickly and\n  accurately: mDCThermalC is a program written in Python for computing lattice thermal\nconductivity of crystalline bulk materials using the modified Debye-Callaway\nmodel. Building upon the traditional Debye-Callaway theory, the modified model\nobtains the lattice thermal conductivity by averaging the contributions from\nacoustic and optical branches based on their specific heat. The only inputs of\nthis program are the phonon spectrum, phonon velocity and Gruneisen parameter,\nall of which can be calculated using third-party ab initio packages, making the\nmethod fully parameter-free. This leads to a fast and accurate evaluation and\nenables high-throughput calculations of lattice thermal conductivity even in\nlarge and complex systems. In addition, this program calculates the specific\nheat and phonon relaxation times for different scattering processes, which will\nbe beneficial for understanding the phonon transfer behavior.",
        "positive": "Phonon dispersion, Raman spectra and evidence for spin-phonon coupling\n  in MnV$_2$O$_4$ from first-principles: MnV$_2$O$_4$ in the spinel structure is known to exhibit coupled orbital and\nspin ordering, and its Raman spectra show interesting anomalies in its\nlow-temperature phase. With a goal to explain this behavior involving coupled\nspins and phonons, we determine here the spin-phonon couplings in MnV$_2$O$_4$\nfrom a theoretical analysis of its phonon spectra and their dependence on\nspin-ordering and electron correlations, obtained from first-principles density\nfunctional theoretical calculations. Using these in an analysis based on a\nLandau-like theory, we uncover the mechanism governing the Raman anomalies\nobserved in its low-temperature phase."
    },
    {
        "anchor": "Crystallization and non-crystallization of Lennard-Jones particles\n  studied by molecular dynamics simulation: What lattice Lennard-Jones (LJ) solid favors, the lattice identification of\nsimulated system and the microstructures of liquid and non-crystalline solid\nare three important questions in condensed physics and material science and are\naddressed in this paper. Both the crystallization and non-crystallization of LJ\nparticles have been investigated by molecular dynamic (MD) simulation without\nsetting any initial Bravais lattice. To identify the Bravais lattice of\nsimulated system, two distribution functions of both the angles between one\nparticle and its nearest neighbors and the distances between particles have\nbeen proposed. The final identification can be made by comparing these two\ncalculated distribution functions with those of ideal Bravais lattices and\nchecking the particle arrangement of simulated system. Our results have shown\nthat simulated systems show either the face-centered cubic (fcc) lattice or the\nhexagonal close-packed (hcp) lattice. The microstructure of non-crystalline\nsystem is similar to that of LJ liquid at a temperature near the\ncrystallization temperature, and shows no order of the second nearest neighbors\nin comparison with that of crystalline system. This paper has proposed a new\nway of investigating the microstructure of material and its evolution, and\npaved the way for MD simulation of large scale particle system consisting of\nmore than one million particles.",
        "positive": "Transport and optical properties of the chiral semiconductor Ag3AuSe2: Previous band structure calculations predicted Ag3AuSe2 to be a semiconductor\nwith a band gap of approximately 1 eV. Here, we report single crystal growth of\nAg3AuSe2 and its transport and optical properties. Single crystals of Ag3AuSe2\nwere synthesized by slow-cooling from the melt, and grain sizes were confirmed\nto be greater than 2 mm using electron backscatter diffraction. Optical and\ntransport measurements reveal that Ag3AuSe2 is a highly resistive semiconductor\nwith a band gap of and activation energy around 0.3 eV. Our first-principles\ncalculations show that the experimentally-determined band gap lies between the\npredicted band gaps from GGA and hybrid functionals. We predict band inversion\nto be possible by applying tensile strain. The sensitivity of the gap to Ag/Au\nordering, chemical substitution, and heat treatment merit further\ninvestigation."
    },
    {
        "anchor": "Thermodynamic dislocation theory of high-temperature deformation in\n  aluminum and steel: The statistical-thermodynamic dislocation theory developed in previous papers\nis used here in an analysis of high-temperature deformation of aluminum and\nsteel. Using physics-based parameters that we expect theoretically to be\nindependent of strain rate and temperature, we are able to fit experimental\nstress-strain curves for three different strain rates and three different\ntemperatures for each of these two materials. Our theoretical curves include\nyielding transitions at zero strain in agreement with experiment. We find that\nthermal softening effects are important even at the lowest temperatures and\nsmallest strain rates.",
        "positive": "Strain-driven light polarization switching in deep ultraviolet nitride\n  emitters: Residual strain plays a critical role in determining the crystalline quality\nof nitride epitaxial layers and in modifying their band structure; this often\nleads to several interesting physical phenomena. It is found, for example, that\ncompressive strain in AlxGa1-xN layers grown on AlyGa1-yN (x<y) templates\nresults in an anti-crossing of the valence bands at considerably much higher Al\ncomposition than expected. This happens even in the presence of large and\nnegative crystal field splitting energy for AlxGa1-xN layers. A judicious\nmagnitude of the compressive strain can support vertical light emission (out of\nthe c-plane) from AlxGa1-xN quantum wells up to x\\approx 0.80, which is\ndesirable for the development of deep ultraviolet light-emitting diodes\ndesigned to operate below 250nm with transverse electric polarization\ncharacteristics."
    },
    {
        "anchor": "Composition and reactivity on Pd/Au(111) surface: A first-principle\n  study: Atomic configurations of two or three Pd substituents on the Au(111) surface\nare investigated using the first-principles pseudopotential plane wave\napproach. Pd atoms are found to form second neighborhoods on PdAu(111). The\nPd-d band becomes narrow and well below the Fermi level, very different from\nthose in a Pd film or bulk Pd. Nevertheless, surface Pd atoms are still active\nand serve as independent attractive centers towards adsorbates. The special\nensembles are important for catalysis applications because of their ability to\nconfine reactants in a small region.",
        "positive": "Spontaneous supercrystal formation during a strain-engineered\n  metal-insulator transition: Mott metal-insulator transitions possess electronic, magnetic, and structural\ndegrees of freedom promising next generation energy-efficient electronics. We\nreport a previously unknown, hierarchically ordered state during a Mott\ntransition and demonstrate correlated switching of functional electronic\nproperties. We elucidate in-situ formation of an intrinsic supercrystal in a\nCa2RuO4 thin film. Machine learning-assisted X-ray nanodiffraction together\nwith electron microscopy reveal multi-scale periodic domain formation at and\nbelow the film transition temperature (TFilm ~ 200-250 K) and a separate\nanisotropic spatial structure at and above TFilm. Local resistivity\nmeasurements imply an intrinsic coupling of the supercrystal orientation to the\nmaterial's anisotropic conductivity. Our findings add an additional degree of\ncomplexity to the physical understanding of Mott transitions, opening\nopportunities for designing materials with tunable electronic properties."
    },
    {
        "anchor": "Quantum oscillations, thermoelectric coefficients and the Fermi surface\n  of semi-metallic WTe2: We present a study of angle-resolved quantum oscillations of electric and\nthermoelectric transport coefficients in semi-metallic WTe$_{2}$, which has the\nparticularity of displaying a large B$^{2}$ magneto-resistance. The Fermi\nsurface consists of two pairs of electron-like and hole-like pockets of equal\nvolumes in a \"Russian doll\" structure. Carrier density, Fermi energy, mobility\nand the mean-free-path of the system are quantified. An additional frequency is\nobserved above a threshold field and attributed to magnetic breakdown across\ntwo orbits. In contrast to all other dilute metals, the Nernst signal remains\nlinear in magnetic field even in the high-field ($\\omega_c\\tau \\gg 1$) regime.\nSurprisingly, none of the pockets extend across the c-axis of the first\nBrillouin zone, making the system a three-dimensional metal with moderate\nanisotropy in Fermi velocity yet a large anisotropy in mean-free-path.",
        "positive": "Unconventional Optical Response in Engineered Au-Ag Nanostructures: This article describes the optical properties of nanostructures composed of\nsilver particles embedded into a gold matrix. In previous studies these\nmaterials were shown to exhibit temperature dependent transitions to a highly\nconductive and strongly diamagnetic state. Here we describe the anomalous\noptical properties of these nanostructures. Most notably, these materials fail\nto obey Mie theory and exhibit an unconventional resonance with a maximum at\nabout 4 eV, while the usual gold and silver localized surface plasmon\nresonances are suppressed. This effect implies a significant deviation from the\nbulk dielectric functions of gold and silver. We further resolved this\nresonance into its absorbance and scattering sub-parts. It is observed that the\nresonance is largely comprised of scattering, with negligible losses even at\nultraviolet frequencies."
    },
    {
        "anchor": "Magnetic phases of skyrmion-hosting GaV$_4$S$_{8-y}$Se$_{y}$ ($y = 0, 2,\n  4, 8$) probed with muon spectroscopy: We present the results of a muon-spin spectroscopy investigation of\nGaV$_4$S$_{8-y}$Se$_{y}$ with $y=0, 2, 4$ and 8. Zero-field measurements\nsuggest that GaV$_{4}$Se$_{8}$ and GaV$_{4}$S$_{8}$ have distinct magnetic\nground states, with the latter material showing an anomalous\ntemperature-dependence of the local magnetic field. It is not possible to\nevolve the magnetic state continuously between these two systems, with the\nintermediate $y=2$ and $4$ materials showing glassy magnetic behaviour at low\ntemperature. The skyrmion lattice (SkL) phase is evident in the $y=0$ and 8\nmaterials through an enhanced response of the muon-spin relaxation to the\nemergent dynamics that accompany the SkL. For our polycrystalline samples of\nGaV$_4$Se$_{8}$, this enhanced dynamic response is confined to a smaller region\nof the magnetic field-temperature phase diagram than the previous reports of\nthe SkL in single crystals.",
        "positive": "Giant saturation magnetization effect in epitaxial Fe16N2 thin films\n  grown on MgO (001) substrate: Whether {\\alpha}double prime-Fe16N2 possesses a giant saturation\nmagnetization (Ms) has been a daunting problem among magnetic researchers for\nalmost 40 years, mainly due to the unshakable faith of famous Slater-Pauling\n(SP) curve and poor consistency on evaluating its Ms. Here we demonstrate that,\nusing epitaxy and mis-fit strain imposed by an underlying substrate, the\nin-plane lattice constant of Fe16N2 thin films can be fine tuned to create\nfavorable conditions for exceptionally large saturation magnetization. Combined\nstudy using polarized neutron reflectometry and X-ray diffraction shows that\nwith increasing strain at the interface the Ms of these film can be changed\nover a broad range, from ~2.1T (non-high Ms) up to ~3.1T (high Ms). We suggest\nthat the equilibrium in-plane lattice constant of Fe16N2 sits in the vicinity\nof the spin crossover point, in which a transition between low spin to high\nspin configuration of Fe sites can be realized with sensitive adjustment of\ncrystal structure."
    },
    {
        "anchor": "Giant Rashba spin splitting in strained KTaO3 ultrathin films for\n  circular photogalvanic currents: Strong Rashba effects at surfaces and interfaces have attracted great\nattention for basic scientific exploration and practical applications. Here,\nthe first-principles investigation shows that giant and tunable Rashba effects\ncan be achieved in KTaO$_3$ (KTO) ultrathin films by applying biaxial stress.\nWhen increasing the in-plane compressive strain nearly to -5\\%, the Rashba spin\nsplitting energy reaches $E_{R}=140$ meV, approximately corresponding to the\nRashba coupling constant $\\alpha_{R}=1.3$ eV {\\AA}. We investigate its\nstrain-dependent crystal structures, energy bands, and related properties, and\nthereby elucidate the mechanism for the giant Rashba effects. Furthermore, we\nshow that giant Rashba spin splitting can be kept in the presence of SrTiO$_3$\ncapping layer and/or Si substrate, and strong circular photogalvanic effect can\nbe achieved to generate spin-polarized currents in the KTO thin films or\nrelated heterostructures, which are promising for future spintronic and\noptoelectronic applications.",
        "positive": "Geometric and disorder -- type magnetic frustration in ferrimagnetic\n  \"114\" Ferrites: Role of diamagnetic Li+ and Zn2+ cation substitution: The comparative study of the substitution of zinc and lithium for iron in the\n\"114\" ferrites, YBaFe4O7 and CaBaFe4O7, shows that these diamagnetic cations\nplay a major role in tuning the competition between ferrimagnetism and magnetic\nfrustration in these oxides. The substitution of Li or Zn for Fe in the cubic\nphase YBaFe4O7 leads to a structural transition to a hexagonal phase\nYBaFe4-xMxO7, for M = Li (0.30 < x < 0.75) and for M = Zn (0.40 < x < 1.50). It\nis seen that for low doping values i.e. x = 0.30 (for Li) and x = 0.40 (for\nZn), these diamagnetic cations induce a strong ferrimagnetic component in the\nsamples, in contrast to the spin glass behaviour of the cubic phase. In all the\nhexagonal phases, YBaFe4-xMxO7 and CaBaFe4-xMxO7 with M = Li and Zn, it is seen\nthat in the low doping regime (x ~ 0.3 to 0.5), the competition between\nferrimagnetism and 2 D magnetic frustration is dominated by the average valency\nof iron. In contrast, in the high doping regime (x ~ 1.5), the emergence of a\nspin glass is controlled by the high degree of cationic disorder, irrespective\nof the iron valency."
    },
    {
        "anchor": "Efficient Real Space Solution of the Kohn-Sham Equations with Multiscale\n  Techniques: We present a multigrid algorithm for self consistent solution of the\nKohn-Sham equations in real space. The entire problem is discretized on a real\nspace mesh with a high order finite difference representation. The resulting\nself consistent equations are solved on a heirarchy of grids of increasing\nresolution with a nonlinear Full Approximation Scheme, Full Multigrid\nalgorithm. The self consistency is effected by updates of the Poisson equation\nand the exchange correlation potential at the end of each eigenfunction\ncorrection cycle. The algorithm leads to highly efficient solution of the\nequations, whereby the ground state electron distribution is obtained in only\ntwo or three self consistency iterations on the finest scale.",
        "positive": "An efficient and accurate decomposition of the Fermi operator: We present a method to compute the Fermi function of the Hamiltonian for a\nsystem of independent fermions, based on an exact decomposition of the\ngrand-canonical potential. This scheme does not rely on the localization of the\norbitals and is insensitive to ill-conditioned Hamiltonians. It lends itself\nnaturally to linear scaling, as soon as the sparsity of the system's density\nmatrix is exploited. By using a combination of polynomial expansion and\nNewton-like iterative techniques, an arbitrarily large number of terms can be\nemployed in the expansion, overcoming some of the difficulties encountered in\nprevious papers. Moreover, this hybrid approach allows us to obtain a very\nfavorable scaling of the computational cost with increasing inverse\ntemperature, which makes the method competitive with other Fermi operator\nexpansion techniques. After performing an in-depth theoretical analysis of\ncomputational cost and accuracy, we test our approach on the DFT Hamiltonian\nfor the metallic phase of the LiAl alloy."
    },
    {
        "anchor": "Some problems of low-dimensional physics: Fermi and kinetic energy are usually calculated in periodic boundary\nconditions model, which is not self-consistent for low-dimensional problems,\nwhere particles are confined. Thus for confined particles the potential box\nmodel was used self-consistently to calculate Fermi and kinetic energies in 3-,\n2-, and 1-dimensional cases. This approach is much more logical and\nself-consistent. Then the conditions for neglecting dimensions, that is\nconditions under which the movement of particles in the box could be considered\nas 2- and 1- dimensional, were derived.",
        "positive": "Spectral Stiffness Microplane Model for Quasibrittle Textile Composites: The present contribution proposes a general constitutive model to simulate\nthe orthotropic stiffness, pre-peak nonlinearity, failure envelopes, and the\npost-peak softening and fracture of textile composites. Following the\nmicroplane model framework, the constitutive laws are formulated in terms of\nstress and strain vectors acting on planes of several orientations within the\nmaterial meso-structure. The model exploits the spectral decomposition of the\northotropic stiffness tensor to define orthogonal strain modes at the\nmicroplane level. These are associated to the various constituents at the\nmesoscale and to the material response to different types of deformation.\nStrain-dependent constitutive equations are used to relate the microplane\neigenstresses and eigenstrains while a variational principle is applied to\nrelate the microplane stresses at the mesoscale to the continuum tensor at the\nmacroscale. Thanks to these features, the resulting spectral stiffness\nmicroplane formulation can easily capture various physical inelastic phenomena\ntypical of fiber and textile composites such as: matrix microcracking,\nmicro-delamination, crack bridging, pullout, and debonding. The application of\nthe model to a twill 2$\\times$2 shows that it can realistically predict its\nuniaxial as well as multi-axial behavior. Furthermore, the model shows\nexcellent agreement with experiments on the axial crushing of composite tubes,\nthis capability making it a valuable design tool for crashworthiness\napplications. The formulation is computationally efficient, easy to calibrate\nand adaptable to other kinds of composite architectures of great current\ninterest such as 2D and 3D braids or 3D woven textiles."
    },
    {
        "anchor": "Frequency-selective near-field enhancement of radiative heat transfer\n  via photonic-crystal slabs: a general computational approach for arbitrary\n  geometries and materials: We demonstrate the possibility of achieving enhanced frequency-selective\nnear-field radiative heat transfer between patterned (photonic crystal) slabs\nat designable frequencies and separations, exploiting a general numerical\napproach for computing heat transfer in arbitrary geometries and materials\nbased on the finite-difference time-domain method. Our simulations reveal a\ntradeoff between selectivity and near-field enhancement as the slab--slab\nseparation decreases, with the patterned heat transfer eventually reducing to\nthe unpatterned result multiplied by a fill factor (described by a standard\nproximity approximation). We also find that heat transfer can be further\nenhanced at selective frequencies when the slabs are brought into a\nglide-symmetric configuration, a consequence of the degeneracies associated\nwith the non-symmorphic symmetry group.",
        "positive": "Theory of single atom manipulation with a scanning probe tip: Force\n  signatures, constant-height, and constant-force scans: We report theoretical results predicting the atomic manipulation of a silver\natom on a Si(001) surface by a scanning probe tip, and providing insight into\nthe manipulation phenomena. A molecular mechanics technique has been used, the\nsystem being described by a quantum chemistry method for the short-range\ninteractions and an analytical model for the long-range ones. Taking into\naccount several shapes, orientations, and chemical natures of the scanning tip,\nwe observed four different ways to manipulate the deposited atom in a\nconstant-height mode. In particular, the manipulation is predicted to be\npossible with a Si(111) tip for different tip shapes and adatom locations on\nthe silicon surface. The calculation of the forces during the manipulation\nrevealed that specific variations can be associated with each kind of process.\nThese force signatures, such as the tip height signatures observed in scanning\ntunneling microscope experiments, could be used to deduce the process involved\nin an experiment. Finally, we present preliminary results about the\nmanipulation in constant-force mode."
    },
    {
        "anchor": "Determination of the Fermi Level Position in Dilute Magnetic\n  Ga$_{1-x}$Mn$_{x}$N Films: We report on a combined theoretical and experimental determination of the\nFermi level position in wurtzite Ga$_{1-x}$Mn$_{x}$N films with $x=4\\%$ and\n$x=10\\%$ as grown by molecular beam epitaxy. By means of ellipsometric\nmeasurements the real part of the frequency-dependent conductivity is\ndetermined. An electronic model in the framework of the effective bond-orbital\nmodel is parameterized in order to theoretically reproduce the measured\ntransport properties. Predictions for the long-wavelength behaviour as a\nfunction of the Fermi level are made. The corresponding density of states\nobtained in this model is in qualitative agreement with first-principle\ncalculations. The absence of a significant experimental peak in the AC\nconductivity for small frequencies indicates that the Fermi level lies in a gap\nbetween two Mn-related impurity bands in the host band gap.",
        "positive": "Visible evidence to magnetism of graphene oxide: Graphene oxide continues to amaze scientific community for multiple\npotentials in a broad span of applications such as catalysts, adsorbents,\noxidants, etc., determined by constant unveiling of its fantastic natures. Of\nthem, magnetism is not ultimately identified and directly observed by naked\neyes. Herein, we report graphene oxide directionally migrated and deposited\ntogether simply under external magnetic field from common Nd-Fe-B magnet,\nwhereas the ferromagnetism of graphene oxide did not exhibit that strong as\niron. Therefore, we illustrated this interesting pathway to keep close to such\n2D carbon materials and potentially promoted magnetic-oriented applications."
    },
    {
        "anchor": "PT-symmetry enabled spin circular photogalvanic effect in\n  antiferromagnetic insulators: The short timescale spin dynamics in antiferromagnets is an attractive\nfeature from the standpoint of ultrafast spintronics. Yet generating highly\npolarized spin currents at room temperature remains a fundamental challenge for\nantiferromagnets. We propose a spin circular photogalvanic effect (spin-CPGE),\nin which circularly polarized light can produce a spin current without net\ncharge current at room temperature, through an \"injection-current-like\"\nmechanism in parity-time(PT)-symmetric antiferromagnetic (AFM) insulators. We\ndemonstrate this effect by first-principles simulations of bilayer CrI3 and\nroom-temperature AFM hematite. Our calculations show that the spin-CPGE is\nsignificant, and the magnitude of spin photo-current is comparable with the\nwidely observed charge photocurrent in ferroelectric materials. Interestingly,\nthis spin photocurrent is not sensitive to spin-orbit interactions, which were\nregarded as fundamental mechanisms for generating spin current. Given the fast\nresponse of light-matter interactions, large energy scale, and insensitivity to\nspin-orbit interactions, our work gives hope to realizing a fast-dynamic and\ntemperature-robust pure spin current in a wide range of PT-symmetric AFM\nmaterials, including weak-relativistic magnetic insulators and topological\naxion insulators.",
        "positive": "Magnetic properties of Fe/Dy multilayers: a Monte Carlo investigation: We investigate the magnetic properties of a Heisenberg ferrimagnetic\nmultilayer by using Monte Carlo simulations. The aim of this work is to study\nthe local structural anisotropy model which is a possible origin of the\nperpendicular magnetic anisotropy in transition metal/rare earth amorphous\nmultilayers. We have considered a face centered cubic lattice where each site\nis occupied by a classical Heisenberg spin. We have introduced in our model of\namorphous multilayers a small fraction of crystallized Fe-Dy nanoclusters with\na mean anisotropy axis along the deposition direction. We show that a\ncompetition in the energy terms takes place between the mean uniaxial\nanisotropy of the Dy atoms in the nanoclusters and the random anisotropy of the\nDy atoms in the matrix."
    },
    {
        "anchor": "Electron spin relaxation in X-valley of indirect bandgap AlxGa1-xAs: A\n  new horizon for the realization of next generation spin-photonic devices: GaAs/AlGaAs quantum well (QW) system is utilized to investigate the electron\nspin relaxation in the satellite X-valley of indirect band gap Al0.63Ga0.37As\nepitaxial layers through polarization resolved photo-luminescence excitation\nspectroscopy. Solving the rate equations, steady state electronic distribution\nin various valleys of AlxGa1-xAs is estimated against continues photo carrier\ngeneration and an expression for the degree of circular polarization (DCP) of\nphotoluminescence coming from the adjacent quantum well (QW) is derived.\nAmalgamating the experimental results with analytical expressions, the X-valley\nelectron spin relaxation time ({\\tau}_S^X) is determined to be 2.7 +/- 0.1 ps\nat 10 K. To crosscheck its validity, theoretical calculations are performed\nbased on Density Functional Theory within the framework of the projector\naugmented wave method, which support the experimental result quite well.\nFurther, temperature dependence of {\\tau}_S^X is studied over 10-80 K range,\nwhich is explained by considering the intra-valley scattering of carriers in\nthe X-valley of indirect band gap AlGaAs barrier layer. It is learnt that the\nstrain induced modification of band structure lifts the degeneracy in X-valley,\nwhich dominates the electron spin relaxation beyond 50 K. Furthermore, the DCP\nspectra of hot electrons in indirect band gap AlGaAs layers is found to be\nsignificantly different compared to that of direct bandgap AlGaAs. It is\nunderstood as a consequence of linear k dependent Dresselhaus spin splitting\nand faster energy relaxation procedure in the X-valley. Findings of this work\ncould provide a new horizon for the realization of next generation\nspin-photonic devices which are less sensitive to Joule heating.",
        "positive": "Mobility of <c+a> dislocations in zirconium: Plasticity in hexagonal close-packed zirconium is mainly controlled by the\nglide of dislocations with 1/3<1-210> Burgers vectors. As these dislocations\ncannot accommodate deformation in the [0001] direction , twinning or glide of\n<c+a> dislocations, i.e. dislocations with 1/3<1-213> Burgers vector, have to\nbe activated. We have performed in situ straining experiments in a transmission\nelectron microscope to study the glide of <c+a> dislocations in two different\nzirconium samples, pure zirconium and Zircaloy-4, at room temperature. These\nexperiments show that <c+a> dislocations exclusively glide in first-order\npyramidal planes with cross-slip being activated. A much stronger lattice\nfriction is opposing the glide of <c+a> dislocations when their orientation\ncorresponds to the <a> direction defined by the intersection of their glide\nplane with the basal plane. This results in long dislocations straightened\nalong <a> which glide either viscously or jerkily. This <a> direction governs\nthe motion of segments with other orientations, whose shape is merely driven by\nthe minimization of the line tension. The friction due to solute atoms is also\ndiscussed."
    },
    {
        "anchor": "A mystery of \"sluggish diffusion\" in high-entropy alloys: the truth or a\n  myth?: High entropy alloys (HEAs) are considered as a novel class of materials with\na large number of components available in nearly equatomic proportions. One of\nthe characteristic properties of HEAs was believed to be so-called \"sluggish\"\ndiffusion. The faith on this myth instead of rigorous experimental analysis\nplayed such a dominant role that the first set of data on interdiffusion, in\nfact based on an improper analysis, were cited in hundreds of articles to state\nthe presence of sluggishness of diffusion rates in high entropy alloys. In this\nreview, the recent data on atomic diffusion in HEAs are critically discussed.\nThe discussion is focused on tracer diffusion which is already measured\ndominantly for polycrystalline, but in some cases for single crystalline\nhigh-entropy alloys. Alternatively, a rigorous analysis of the interdiffuson\nexperiments, which provide the diffusion rates of chemical species, too,\nbecomes more and more sophisticated for three and more elements in an alloy and\nit is challenging to derive physically sound quantities from a general\nmulticomponent diffusion experiment. Most promising in this case is the\ndiffusion couple technique, especially the so-called pseudo-binary approach.\nThis approach is analyzed with a focus on the applicability and the possible\nerrors induced if up-hill diffusion appears. It is shown that atomic diffusion\nin HEAs cannot a priori be considered as sluggish and both atomic interactions\nas well as correlation effects are responsible for the observed trends. Even if\nestimated on the same homologous scale, the diffusion retardation induced by a\n\"high entropy\" in FCC crystals is not simply proportional to the number of\nalloying components and it is shown to be similar to that induced by the L12\nordering in a binary system. Furthermore, the importance of cross-correlations\nin diffusion of different species in HEAs is highlighted.",
        "positive": "Band gap unification of partially Si-substituted single wall carbon\n  nanotubes: The atomic and electronic structure of a set of pristine single wall SiC\nnanotubes as well as Si-substituted carbon nanotubes and a SiC sheet was\nstudied by the LDA plane wave band structure calculations. Consecutive\nsubstitution of carbon atoms by Si leads to a gap opening in the energetic\nspectrum of the metallic (8,8) SWCNT with approximately quadratic dependence of\nthe band gap upon the Si concentration. The same substitution for the\nsemiconductor (10,0) SWCNT results in a band gap minimum (0.27 eV) at ~25% of\nSi concentration. In the Si concentration region of 12-18%, both types of\nnanotubes have less than 0.5 eV direct band gaps at the Gamma-Gamma point. The\ncalculation of the chiral (8,2) SWSi_0.15C_0.85NT system gives a similar (0.6\neV) direct band gap. The regular distribution of Si atoms in the atomic lattice\nis by ~0.1 eV/atom energetically preferable in comparison with a random\ndistribution. Time dependent DFT calculations showed that the silicon\nsubstitution sufficiently increases (roughly by one order of magnitude) the\ntotal probability of optical transitions in the near infrared region, which is\ncaused by the opening of the direct band gap in metallic SWCNTs, the\nunification of the nature and energy of band gaps of all SWCNT species, the\nlarge values of <Si3p|r|Si3s> radial integrals and participation of Si3d states\nin chemical bonding in both valence and conductance bands."
    },
    {
        "anchor": "A Generalizable Machine-learning Potential of Ag-Au Nanoalloys and its\n  Application on Surface Reconstruction, Segregation and Diffusion: Owing to the excellent catalysis properties of Ag-Au binary nanoalloy,\nnanostructured Ag-Au, such as Ag-Au nanoparticles and nanopillars, have been\nunder intense investigation. To achieve high accuracy in molecular simulations\nof the Ag-Au nanoalloys, the surface properties are required to be modeled with\nfirst-principles precision. In this work, we propose a generalizable\nmachine-learning interatomic potential for the Ag-Au nanoalloys based on deep\nneural networks, trained from a database constructed with the first-principle\ncalculations. This potential is highlighted by the accurate prediction of Au\n(111) surface reconstruction and the segregation of Au towards the Ag-Au\nnanoalloy surface, where the empirical force field failed in both cases.\nMoreover, regarding the adsorption and diffusion of adatoms on surfaces, the\noverall performance of our potential is better than the empirical force fields.\nWe stress that the reported surface properties are blind to the potential\nmodeling in the sense that none of the surface configurations is explicitly\nincluded in the training database, therefore, the reported potential is\nexpected to have a strong ability of generalization to a wide range of\nproperties and to play a key role in the investigation of nanostructured Ag-Au\nevolution, where the accurate descriptions of free surfaces are necessary.",
        "positive": "First Principles Modeling of Mn(II) Migration above and Dissolution from\n  Li(x)Mn(2)O(4) (001) Surfaces: Density functional theory and ab initio molecular dynamics simulations are\napplied to investigate the migration of Mn(II) ions to above-surface sites on\nspinel Li(x)Mn(2)O(4) (001) surfaces, the subsequent Mn dissolution into the\norganic liquid electrolyte, and the detrimental effects on graphite anode solid\nelectrolyte interphase (SEI) passivating films after Mn(II) ions diffuse\nthrough the separator. The dissolution mechanism proves complex, the\nmuch-quoted Hunter disproportionation of Mn(III) to form Mn(II) is far from\nsufficient. Key steps that facilitate Mn(II) loss include concerted\nliquid/solid-state motions, proton-induced weakening of Mn-O bonds forming\nmobile OH- surface groups, and chemical reactions of adsorbed decomposed\norganic fragments. Mn(II) lodged between the inorganic Li(2)CO(3) and organic\nlithium ethylene dicarbonate (LEDC) anode SEI components facilitates\nelectrochemical reduction and decomposition of LEDC. These findings help inform\nfuture design of protective coatings, electrolytes, additives, and interfaces."
    },
    {
        "anchor": "Construction of accurate machine learning force fields for copper and\n  silicon dioxide: Recently, the machine learning force field has emerged as a powerful atomic\nsimulation approach for its high accuracy and low computational cost. However,\nits applications in the multi-component materials are relatively less. In this\nstudy, the ML force fields are constructed for both elemental material (Cu) and\nbinary material (SiO2). The atomic environments are described by the structural\nfingerprint that takes the bond angle into account, and then, different ML\ntechniques, including linear regression, neural network and mixture model\nmethod, are used to learn the structure-force relationship. We found that the\nuse of angular structural fingerprint and mixture model method significantly\nimproves the accuracy of ML force fields. In addition, we discussed the\neffective structural fingerprints auto-selection method based on LASSO and the\ngenetic algorithm. The atomic simulations carried out with ML force fields are\nin excellent agreement with ab initio calculations.",
        "positive": "Engineering relativistic effects in ferroelectric SnTe: Spin-orbit coupling is increasingly seen as a rich source of novel phenomena,\nas shown by the recent excitement around topological insulators and Rashba\neffects. We here show that the addition of ferroelectric degrees of freedom to\na semiconductor featuring topologically-non-trivial properties, such as SnTe,\nmerges the intriguing field of spin-orbit-driven physics with non-volatile\nfunctionalities appealing for spintronics. By using a variety of modelling\ntechniques, we show that a strikingly rich sequence of phases can be induced in\nSnTe, when going from a room-temperature cubic phase to a low-temperature\nferroelectric structure, ranging from a topological crystalline insulator to a\ntime-reversal-invariant $Z_2$ topological insulator to a \"ferroelectric Rashba\nsemiconductor\", exhibiting a huge electrically-controllable Rashba effect in\nthe bulk band structure."
    },
    {
        "anchor": "Multiple Dirac cones at the surface of the topological metal LaBi: The rare-earth monopnictide LaBi exhibits exotic magneto-transport properties\nincluding an extremely large and anisotropic magnetoresistance. Experimental\nevidence for topological surface states is still missing although band\ninversions have been postulated to induce a topological phase in LaBi. By\nemploying angle-resolved photoemission spectroscopy (ARPES) in conjunction with\n$ab~initio$ calculations, we have revealed the existence of surface states of\nLaBi through the observation of three Dirac cones: two coexist at the corners\nand one appears at the center of the Brillouin zone. The odd number of surface\nDirac cones is a direct consequence of the odd number of band inversions in the\nbulk band structure, thereby proving that LaBi is a topological, compensated\nsemi-metal, which is equivalent to a time-reversal invariant topological\ninsulator. Our findings provide insight into the topological surface states of\nLaBi's semi-metallicity and related magneto-transport properties.",
        "positive": "Oxide layer thickness effects on the resistance switching\n  characteristics of Ti/TiO2-NT/Au structure: Self-ordered nanotubular titania TiO2-NT with outer tube diameter of 45 nm\nare synthesized using the anodic oxidation of titanium foil. Four sets of\nmemristors with 100 ${\\mu}m$ diameter based on Ti/TiO2-NT/Au sandwich\nstructures with an oxide layer thickness of 80, 120, 160 and 200 nm are\nfabricated. Current-voltage (CV) characteristics for the obtained samples in\nthe static and dynamic operation modes are studied. Resistance in high and low\nresistance states is estimated. Basing on the analysis of the CV\ncharacteristics in dynamic mode (> 14 000 switchings) a prospective of use for\nsynthesized Ti/TiO2-NT/Au micromemristors with oxide layer thickness of 160 nm\nin non-volatile memory is shown.\n  Keywords: anodic titania, titanium dioxide nanotubes, nanotubular structure,\nmemristor, resistive switching"
    },
    {
        "anchor": "Effect of multinary substitution on electronic and transport properties\n  of TiCoSb based half-Heusler alloys: The electronic structures of TixZrx/2CoPbxTex, TixZrx/2Hfx/2CoPbxTex (x =\n0.5), and the parent compound TiCoSb were investigated using the full potential\nlinearized augmented plane wave method. The thermoelectric transport properties\nof these alloys are calculated on the basis of semi-classical Boltzmann\ntransport theory. From the band structure calculations we show that the\nsubstitution of Zr,Hf in the Ti site and Pb and Te in the Sb site lower the\nband gap value and also change the indirect band (IB) gap of TiCoSb to the\ndirect band (DB) gap. The calculated band gap of TiCoSb, TixZrx/2CoPbxTex, and\nTixZrx/2Hfx/2CoPbxTex are 1.04 eV (IB), 0.92 eV (DB), and 0.93 eV (DB),\nrespectively. All these alloys follow the empirical rule of 18 valence-electron\ncontent which is essential for bringing semiconductivity in half Heusler\nalloys. It is shown that the substitution of Hf at the Ti site improve the ZT\nvalue (~1.05) at room temperature, whereas there is no significant difference\nin ZT is found at higher temperature. Based on the calculated thermoelectric\ntransport properties, we conclude that the appropriate concentration of Hf\nsubstitution can further improve the thermoelectric performance of\nTixZrx/2Hfx/2CoPbxTex.",
        "positive": "Local sheet conductivity and sheet current density mapping using a\n  single scanning voltage probe: We demonstrate how a single scanning voltage probe can be used to map the\nlocal conductivity and current density in a thin film with no a priori\nknowledge of the geometry of the electrical contacts. With state-of-the-art\nscanning voltage probes, under appropriate conditions such mapping should be\npossible down to nanometer scales. The technique requires two non-colinear\nvoltage scans. When only one voltage map is available, determination of the\nconductivity is not possible because the solution to the governing equation is\nnot unique. The only restriction on the technique is that the sheet\nconductivity is a local function of position."
    },
    {
        "anchor": "Evanescent Gain in \"Trapped Rainbow\" Negative Refractive Index\n  Heterostructures: We theoretically and numerically analyze a five-layer \"trapped rainbow\"\nwaveguide made of a passive negative refractive index (NRI) core layer and gain\nstrips in the cladding. Analytic transfer-matrix calculations and full-wave\ntime-domain simulations are deployed to calculate, both in the frequency- and\nin the time-domain, the losses or gain experienced by complex-wavevector and\ncomplex-frequency modes. We find an excellent agreement between five distinct\nsets of results, all showing that the use of evanescent pumping (gain) can\ncompensate the losses in the NRI slow-light regime.",
        "positive": "Direct Observation of Giant Saturation Magnetization in Fe16N2: Magnetic materials with giant saturation magnetization have been a holy grail\nfor magnetic researchers and condensed matter physicists for decades because of\nits great scientific and technological impacts. As described by the famous\nSlater-Pauling curve the material with highest Ms is the Fe65Co35 alloy. This\nwas challenged in 1972 by a report on the compound Fe16N2 with Ms much higher\nthan that of Fe65Co35. Following this claim, there have been enormous efforts\nto reproduce this result and to understand the magnetism of this compound.\nHowever, the reported Ms by different groups cover a broad range, mainly due to\nthe unavailability of directly assessing Ms in Fe16N2. In this article, we\nreport a direct observation of the giant saturation magnetization up to 2500\nemu/cm3 using polarized neutron reflectometry (PNR) in epitaxial constrained\nFe16N2 thin films prepared using a low-energy and surface-plasma-free\nsputtering process. The observed giant Ms is corroborated by a previously\nproposed Cluster + Atom model, the characteristic feature of which, namely, the\ndirectional charge transfer is evidenced by polarization-dependent x-ray\nabsorption near edge spectroscopy (XANES)."
    },
    {
        "anchor": "Photoinduced Phase Transitions: Optically induced ultrafast electronic excitations with sufficiently long\nlifetimes may cause strong effects on phase transitions like structural and\nnonmetal to metal ones. Examples are transitions diamond to graphite, graphite\nto graphene, non-metal to metal, solid to liquid and vapor to liquid, solid. A\nspectacular case is photo-induced water condensation. These non-equilibrium\ntransitions are an ultrafast response, on a few hundred fs-time scale, to the\nfast electronic excitations. The energy of the photons is converted into\nelectronic one via electronic excitations changing the cohesive energy. This\nchanges the chemical potential controlling the phase transition. In view of the\nadvances in laser optics photon induced transitions are expected to become an\nactive area in non-equilibrium physics and phase transition dynamics.\nConservation laws like energy or angular momentum conservation control the time\nduring which the transitions occur. Since the photon induced effects result\nlargely from weakening or strenghtening of the bonding between the atoms or\nmolecules transitions like solid/liquid etc. can be shifted in both directions.\nPhotoinduced transitions will be discussed from an unified point of view.",
        "positive": "Topologically confined states at corrugations of gated bilayer graphene: We investigate the electronic and transport properties of gated bilayer\ngraphene with one corrugated layer, which results in a stacking AB/BA boundary.\nWhen a gate voltage is applied to one layer, topologically protected gap states\nappear at the corrugation, which reveal as robust transport channels along the\nstacking boundary. With increasing size of the corrugation, more localized,\nquantum-well-like states emerge. These finite-size states are also conductive\nalong the fold, but in contrast to the stacking boundary states, which are\ngapless, they present a gap. We have also studied periodic corrugations in\nbilayer graphene; our findings show that such corrugations between AB- and\nBA-stacked regions behave as conducting channels that can be easily identified\nby their shape."
    },
    {
        "anchor": "A non-isothermal, non-equimolar transient kinetic model for gas-solid\n  reactions: A numerical model is presented, designed to simulate the kinetic and thermal\nbehaviour of a porous pellet in which any gas-solid reaction is taking place.\nIts novelty consists in the fact that it can deal with reactions whether they\nare exothermic or endothermic, whether they are equimolar or not, whether they\nare reversible or irreversible, and further reactions in the transient regime\nand even the possible presence of inert gases and solids can be treated. The\nnumerical scheme is based on the finite volume method in an implicit\nformulation, with a specific treatment of the thermal source term for strongly\nexothermic reactions. The model was validated by comparison with analytical and\nnumerical solutions from the literature and was used to simulate the exothermic\nreaction involved in the oxidation of zinc sulphide.",
        "positive": "Ge growth on ion-irradiated Si self-affine fractal surfaces: We have carried out scanning tunneling microscopy experiments under ultrahigh\nvacuum condition to study the morphology of ultrathin Ge films eposited on\npristine Si(100) and ion-irradiated Si(100) self-affine fractal surfaces. The\npristine and the ion-irradiated Si(100) surface have roughness exponents of\nalpha=0.19+/-0.05 and alpha=0.82+/-0.04 respectively. These measurements were\ncarried out on two halves of the same sample where only one half was\nion-irradiated. Following deposition of a thin film of Ge (~6 A) the roughness\nexponents change to 0.11+/-0.04 and 0.99+/-0.06, respectively. Upon Ge\ndeposition, while the roughness increases by more than an order of magnitude on\nthe pristine surface, a smoothing is observed for the ion-irradiated surface.\nFor the ion-irradiated surface the correlation length xi increases from 32 nm\nto 137 nm upon Ge deposition. Ge grows on Si surfaces in the Stranski-Krastanov\nor layer-plus-island mode where islands grow on a wetting layer of about three\natomic layers. On the pristine surface the islands are predominantly of square\nor rectangular shape, while on the ion-irradiated surface the islands are\nnearly diamond shaped. Changes of adsorption behaviour of deposited atoms\ndepending on the roughness exponent (or the fractal dimension) of the substrate\nsurface are discussed."
    },
    {
        "anchor": "Carrier mediated reduction of stiffness in nanoindented crystalline\n  Si(100): We report the observation of carrier mediated decrease in the stiffness of\ncrystalline (c)-Si(100) under nanoindentation. The apparent elastic modulii of\nheavily dopes (1E21 cm-3) p- and n-type c-Si are observed to be lower by 5.-7.5\npercent that the estimated value for intrinsic (1E14 cm-3) c-Si. The deviation\nobserved with respect to elastic modulus remarkably matches with the estimated\nvalue while considering the electronic elastic strain effect on carrier\nconcentration as an influence of negative pressure coefficient of band gap for\nSi. The value is predominantly higher than the reported value of a decrease of\n1-3 percent in stiffness as an effect of impurity in c-Si.",
        "positive": "Predicted reentrant melting of dense hydrogen at ultra-high pressures: The phase diagram of hydrogen is one of the most important challenges in\nhigh-pressure physics and astrophysics. Especially, the melting of dense\nhydrogen is complicated by dimer dissociation, metallization and nuclear\nquantum effect of protons, which together lead to a cold melting of dense\nhydrogen when above 500 GPa. Nonetheless, the variation of the melting curve at\nhigher pressures is virtually uncharted. Here we report that using ab initio\nmolecular dynamics and path integral simulations based on density functional\ntheory, a new atomic phase is discovered, which gives an uplifting melting\ncurve of dense hydrogen when beyond 2 TPa, and results in a reentrant\nsolid-liquid transition before entering the Wigner crystalline phase of\nprotons. The findings greatly extend the phase diagram of dense hydrogen, and\nput metallic hydrogen into the group of alkali metals, with its melting curve\nclosely resembling those of lithium and sodium. [With erratum. And the\nstructural information of C2221 phase is also provided in this version]"
    },
    {
        "anchor": "Machine learning density functionals from the random-phase approximation: Kohn-Sham density functional theory (DFT) is the standard method for\nfirst-principles calculations in computational chemistry and materials science.\nMore accurate theories such as the random-phase approximation (RPA) are limited\nin application due to their large computational cost. Here, we construct a DFT\nsubstitute functional for the RPA using supervised and unsupervised machine\nlearning (ML) techniques. Our ML-RPA model can be interpreted as a non-local\nextension to the standard gradient approximation. We train an ML-RPA functional\nfor diamond surfaces and liquid water and show that ML-RPA can outperform the\nstandard gradient functionals in terms of accuracy. Our work demonstrates how\nML-RPA can extend the applicability of the RPA to larger system sizes, time\nscales and chemical spaces.",
        "positive": "Preparation and ferroelectric properties of (124)-oriented SrBi4Ti4O15\n  ferroelectric thin film on (110)-oriented LaNiO3 electrode: A (124)-oriented SrBi4Ti4O15 (SBTi) ferroelectric thin film with high volume\nfraction of {\\alpha}SBTi(124)=97% was obtained using a metal organic\ndecomposition process on SiO2/Si substrate coated by (110)-oriented LaNiO3\n(LNO) thin film. The remanent polarization and coercive field for\n(124)-oriented SBTi film are 12.1 {\\mu}C/cm2 and 74 kV/cm, respectively. No\nevident fatigue of (124)-oriented SBTi thin film can be observed after\n1{\\times}10e9 switching cycles. Besides, the (124)-oriented SBTi film can be\nuniformly polarized over large areas using a piezoelectric-mode atomic force\nmicroscope. Considering that the annealing temperature was 650{\\deg}C and the\nthickness of each deposited layer was merely 30 nm, a long-range epitaxial\nrelationship between SBTi(124) and LNO(110) facets was proposed. The epitaxial\nrelationship was demonstrated based on the crystal structures of SBTi and LNO."
    },
    {
        "anchor": "Type-I and type-II Dirac fermions in graphene with nitrogen-molecule\n  line defects: Recently, type-II Dirac fermions characterized by strongly titled Dirac cones\nhave been proposed. The new fermions exhibit unique physical properties\ndifferent from the type-I Dirac fermions in graphene, and thus attract\ntremendous attentions. Up to date, all type-II fermions are only found in the\nheavy compounds with strong spin obit coupling. Here, we propose that both\ntype-I and type-II Dirac fermions can exist in the graphene embedding\nnitrogen-molecule line defects (NMLDs). While the types of Dirac fermions are\ndetermined by the size W of graphene nanoribbons between the line defects. By\ncomparing the two types of Dirac fermions, their different physical properties\nand originations are revealed directly. Remarkably, the type-I Dirac points\ninduce one Fermi arc corresponding to edge states along the armchair direction,\nwhile the type-II Dirac points induce two Fermi arcs corresponding to two sets\nof edge states along the zigzag direction. These results not only expand our\nviews on the Dirac fermions in two-dimensional structures, but also extend\ntheir applications in electronics.",
        "positive": "A review of thermal transport and electronic properties of borophene: In recent years, two-dimensional boron sheets (borophene) have been\nexperimentally synthesized and theoretically observed as promising conductor or\ntransistor with novel thermal and electronic properties. We first give a\ngeneral survey of some notable electronic properties of borophene, including\nthe superconductivity and topological characters. We then mainly review the\nbasic approaches, thermal transport, as well as the mechanical properties of\nborophene with different configurations. This review gives a general\nunderstanding of some of the crucial thermal transport and electronic\nproperties of borophene, and also calls for further experimental investigations\nand applications on certain scientific community."
    },
    {
        "anchor": "Retention and Recycling of Deuterium in Liquid Lithium-Tin Slab Studied\n  by First-Principles Molecular Dynamics: Understanding the retention and recycling of hydrogen isotopes in liquid\nmetal plasma-facing materials such as liquid Li, Sn, and Li-Sn are of\nfundamental importance in designing magnetically confined fusion reactors. We\nperform first-principles molecules dynamics simulations of liquid Li-Sn slab\nwith inserted D atoms to provide microscopic insights into the interactions of\nD with Li-Sn liquid metal. We observe evaporation of D$_2$ and LiD molecules\nout of the Li-Sn slabs. With detailed analysis, we unveil a cooperative process\nof forming D$_2$ molecules in liquid Li-Sn, where Li atoms act as catalytic\ncenters to trap a D atom before another D comes nearby to form a molecule, and\nthe surplus charges are transferred from D$_2$ to nearby Sn atoms. Furthermore,\nwe predict a temperature window in which D$_2$ molecules can escape to vacuum,\nwhile LiD molecules cannot. The above findings deepen our understanding of\ninteractions between hydrogen isotopes and Li-Sn liquid metal.",
        "positive": "Voltage-induced strain control of the magnetic anisotropy in a Ni thin\n  film on flexible substrate: Voltage-induced magnetic anisotropy has been quantitatively studied in\npolycrystalline Ni thin film deposited on flexible substrate using microstrip\nferromagnetic resonance. This anisotropy is induced by a piezoelectric actuator\non which the film/substrate system was glued. In our work, the control of the\nanisotropy through the applied elastic strains is facilitated by the compliant\nelastic behavior of the substrate. The in-plane strains in the film induced by\nthe piezoelectric actuation have been measured by the digital image correlation\ntechnique. Non-linear variation of the resonance field as function of the\napplied voltage is found and well reproduced by taking into account the non\nlinear and hysteretic variations of the induced in-plane strains as function of\nthe applied voltage. Moreover, we show that initial uniaxial anisotropy\nattributed to compliant substrate curvature is fully compensated by the voltage\ninduced anisotropy."
    },
    {
        "anchor": "Large Frequency Change with Thickness in Interlayer Breathing Mode -\n  Significant Interlayer Interactions in Few Layer Black Phosphorus: Bulk black phosphorus (BP) consists of puckered layers of phosphorus atoms.\nFew-layer BP, obtained from bulk BP by exfoliation, is an emerging candidate as\na channel material in post-silicon electronics. A deep understanding of its\nphysical properties and its full range of applications are still being\nuncovered. In this paper, we present a theoretical and experimental\ninvestigation of phonon properties in few-layer BP, focusing on the\nlow-frequency regime corresponding to interlayer vibrational modes. We show\nthat the interlayer breathing mode A3g shows a large redshift with increasing\nthickness; the experimental and theoretical results agreeing well. This\nthickness dependence is two times larger than that in the chalcogenide\nmaterials such as few-layer MoS2 and WSe2, because of the significantly larger\ninterlayer force constant and smaller atomic mass in BP. The derived interlayer\nout-of-plane force constant is about 50% larger than that in graphene and MoS2.\nWe show that this large interlayer force constant arises from the sizable\ncovalent interaction between phosphorus atoms in adjacent layers, and that\ninterlayer interactions are not merely of the weak van der Waals type. These\nsignificant interlayer interactions are consistent with the known surface\nreactivity of BP, and have been shown to be important for electric-field\ninduced formation of Dirac cones in thin film BP.",
        "positive": "Enhanced Curie temperature and skyrmion stability in room temperature\n  ferromagnetic semiconductor CrISe monolayer: We report CrISe monolayer as a room temperature ferromagnetic semiconductor\nwith the Curie temperature ($T_C$), magnetic anisotropy energy (MAE) and band\ngap being 322 K, 113 $\\mu$eV and 0.67 eV, respectively. The $T_C$ and MAE can\nbe further enhanced up to 385 K and 313 $\\mu$eV by tensile strain. More\ninterestingly, the magnetic easy axis can be switched between off-plane and\nin-plane by compressive strain. Particularly, due to the broken inversion\nsymmetry and strong spin-orbit coupling of Se atoms, a large\nDzyaloshinskii-Moriya interaction (DMI) of 2.40 meV is obtained. More\nimportantly, by micromagnetic simulations, stable skyrmions with sub-10 nm\nradius are stabilized by the large DMI above room temperature in a wide range\nof strain from $-2\\%$ to $6\\%$. Our work demonstrates CrISe as a promising\ncandidate for next-generation skyrmion-based information storage devices and\nprovides guidance for the research of DMI and skyrmions in room temperature\nferromagnetic semiconductors."
    },
    {
        "anchor": "Linear Dichroism Conversion in Quasi One-Dimensional Perovskite\n  Chalcogenide: Anisotropic photonic materials with linear dichroism are crucial components\nin many sensing, imaging and communication applications. Such materials play an\nimportant role as polarizers, filters and wave-plates in photonic devices and\ncircuits. Conventional crystalline materials with optical anisotropy typically\nshow unidirectional linear dichroism over a broad wavelength range. The linear\ndichroism conversion phenomenon has not been observed in crystalline materials.\nHere, we report the investigation of the unique linear dichroism conversion\nphenomenon in quasi-one-dimensional (quasi-1D) hexagonal perovskite\nchalcogenide BaTiS3. The material shows record level of optical anisotropy\nwithin the visible wavelength range. In contrast to conventional anisotropic\noptical materials, the linear dichroism polarity in BaTiS3 makes an orthogonal\nchange at an optical wavelength corresponding to the photon energy of 1.78 eV.\nFirst principle calculations reveal that this anomalous linear dichroism\nconversion behavior originates from different selection rules of the optical\ntransitions from the parallel bands in the BaTiS3 material. Wavelength\ndependent polarized Raman spectroscopy further confirms this phenomenon. Such\nmaterial with linear dichroism conversion property can facilitate new ability\nto control and sense the energy and polarization of light, and lead to novel\nphotonic devices such as polarization-wavelength selective detectors and lasers\nfor multispectral imaging, sensing and optical communication applications.",
        "positive": "Phonon-limited Mobility of 2D Semiconductors: Quadrupole Scattering and\n  Free-carrier Screening: Two-dimensional (2D) semiconductors have demonstrated great potential for\nnext-generation electronics and optoelectronics. An important property for\nthese applications is the phonon-limited charge carrier mobility. The common\napproach to calculate the mobility from first principles relies on the\ninterpolation of the electron-phonon coupling (EPC) matrix. However, it\nneglects the scattering by the dynamical quadrupoles generated by phonons,\nlimiting its accuracy. Here we present a first-principles method to incorporate\nthe quadrupole scattering, which results in a much better interpolation quality\nand thus a more accurate mobility as exemplified by monolayer MoS2 and InSe.\nThis method also allows for a natural incorporation of the effects of the free\ncarriers, enabling us to efficiently compute the screened EPC and thus the\nmobility for doped semiconductors. Particularly, we find that the electron\nmobility of InSe is more sensitive to the carrier concentration than that of\nMoS2 due to the stronger long-range scattering in intrinsic InSe. With\nincreasing electron concentration, the InSe mobility can reach ~4 times of the\nintrinsic value, then decrease owing to the involvement of heavier electronic\nstates. Our work provides accurate and efficient methods to calculate the\nphonon-limited mobility in the intrinsic and doped 2D materials, and improves\nthe fundamental understanding of their transport mechanism."
    },
    {
        "anchor": "Absorption $\\textit{versus}$ Adsorption: High-Throughput Computation of\n  Impurities in 2D Materials: Doping of a two-dimensional (2D) material by impurity atoms occurs\n\\textit{via} two distinct mechanisms: absorption of the dopants by the 2D\ncrystal or adsorption on its surface. To distinguish the relevant mechanism, we\nsystematically dope 53 experimentally synthesized 2D monolayers by 65 different\nchemical elements in both absorption and adsorption sites. The resulting 17,598\ndoped monolayer structures were generated using the newly developed ASE\n\\texttt{DefectBuilder} -- a Python tool to set up point defects in 2D and bulk\nmaterials -- and subsequently relaxed by an automated high-throughput density\nfunctional theory (DFT) workflow. We find that interstitial positions are\npreferred for small dopants with partially filled valence electrons in host\nmaterials with large lattice parameters. On the contrary, adatoms are favored\nfor dopants with a low number of valence electrons due to lower coordination of\nadsorption sites compared to interstitials. The relaxed structures,\ncharacterization parameters, defect formation energies, and magnetic moments\n(spins) are available in an open database to help advance our understanding of\ndefects in 2D materials.",
        "positive": "Giant widening of interface magnetic layer in almost compensated iron\n  garnet: A two-sublattice ferrimagnet undergoes a transition from a collinear to\ncanted magnetic phase at magnetic field oriented along an easy magnetization\ndirection. In this work, we study the transition by means of the\nmagneto-optical Faraday effect in a thin film of compensated iron garnet\n(Lu$_{3-{\\rm{x}}}$Bi$_{\\rm{x}}$)(Fe$_{5-{\\rm{y}}-{\\rm{z}}}$Ga$_{\\rm{y}}$Al$_{\\rm{z}}$)O$_{12}$\ngrown on Gd$_3$Ga$_5$O$_{12}$ substrate. In the immediate vicinity of the\ncompensation temperature a precursor of the transition with a complex shape was\nobserved. Using a special sample with variable thickness we demonstrate an\ninterfacial origin of the precursor. Diffusion of gadolinium from the substrate\ninto the film forms a thin intermixed layer with enhanced magnetization. It\ninduces an extended inhomogeneous magnetic structure in the film. A two-step\nshape of the precursor appears due to an easy-plane anisotropy of the\nintermixed magnetic layer. We emphasize that an effective width of the\ninhomogeneous magnetization distribution in the film grows enormously while\napproaching the compensation temperature."
    },
    {
        "anchor": "Magnetic anisotropy driven by ligand in 4d transition metal oxide SrRuO3: The origin of magnetic anisotropy in magnetic compounds is a longstanding\nissue in solid state physics and nonmagnetic ligand ions are considered to\ncontribute little to magnetic anisotropy. Here, we introduce the concept of\nligand driven magnetic anisotropy in a complex transition-metal oxide. We\nconducted X ray absorption and X ray magnetic circular dichroism spectroscopies\nat the Ru and O edges in the 4d ferromagnetic metal SrRuO3. Systematic\nvariation of the sample thickness in the range below 10 nm allowed us to\ncontrol the localization of Ru 4d t2g states, which affects the magnetic\ncoupling between the Ru and O ions. We found that the orbital magnetization of\nthe ligand induced via hybridization with the Ru 4d orbital determines the\nmagnetic anisotropy in SrRuO3.",
        "positive": "Formation of atomic nanoclusters on graphene sheets: The formation of atomic nanoclusters on suspended graphene sheets have been\ninvestigated by employing a Molecular dynamics simulation at finite\ntemperature. Our systematic study is based on temperature dependent Molecular\ndynamics simulations of some transition and alkali atoms on suspended graphene\nsheets. We find that the transition atoms aggregate and make various size\nnanoclusters distributed randomly on graphene surface. We also report that most\nalkali atoms make one atomic layer on graphene sheets. Interestingly, the\npotassium atoms almost deposit regularly on the surface at low temperature. We\nexpect from this behavior that the electrical conductivity of a suspended\ngraphene doped by potassium atoms would be much higher than the case doped by\nthe other atoms at low temperature."
    },
    {
        "anchor": "Lithium Diffusion & Magnetism in Battery Cathode Material\n  LixNi1/3Co1/3Mn1/3O2: We have studied low-temperature magnetic properties as well as\nhigh-temperature lithium ion diffusion in the battery cathode materials\nLixNi1/3Co1/3Mn1/3O2 by the use of muon spin rotation/relaxation. Our data\nreveal that the samples enter into a 2D spin-glass state below TSG=12 K. We\nfurther show that lithium diffusion channels become active for T>Tdiff=125 K\nwhere the Li-ion hopping-rate [nu(T)] starts to increase exponentially.\nFurther, nu(T) is found to fit very well to an Arrhenius type equation and the\nactivation energy for the diffusion process is extracted as Ea=100 meV.",
        "positive": "Combined cluster and atomic displacement expansion for solid solutions\n  and magnetism: Finite temperature disordered solid solutions and magnetic materials are\ndifficult to study directly using first principles calculations, due to the\nlarge unit cells and many independent samples that are required. In this work,\nwe develop a combined cluster expansion and atomic displacement expansion,\nwhich we fit to first principles energies, forces, and stresses. We then use\nthe expansion to calculate thermodynamic quantities at nearly first principles\nlevels of accuracy. We demonstrate that by treating all the relevant degrees of\nfreedom explicitly, we can achieve improved convergence properties as compared\nto a simple cluster expansion, and our model naturally includes both\nconfigurational and vibrational entropy. In addition, we can treat coupling\nbetween structural and chemical or magnetic degrees of freedom. As examples, we\nuse our expansion to calculate properties of Si$_{1-x}$Ge$_x$, magnetic MnO, Al\nwith vacancies, and Ba$_x$Sr$_{1-x}$TiO$_3$."
    },
    {
        "anchor": "Damping of Landau levels in neutral graphene at low magnetic fields: A\n  phonon Raman scattering study: Landau level broadening mechanisms in electrically neutral and quasineutral\ngraphene were investigated through micro-magneto-Raman experiments in three\ndifferent samples, namely, a natural single-layer graphene flake and a\nback-gated single-layer device, both deposited over Si/SiO2 substrates, and a\nmultilayer epitaxial graphene employed as a reference sample. Interband Landau\nlevel transition widths were estimated through a quantitative analysis of the\nmagnetophonon resonances associated with optically active Landau level\ntransitions crossing the energy of the E_2g Raman-active phonon. Contrary to\nmultilayer graphene, the single-layer graphene samples show a strong damping of\nthe low-field resonances, consistent with an additional broadening contribution\nof the Landau level energies arising from a random strain field. This extra\ncontribution is properly quantified in terms of a pseudomagnetic field\ndistribution Delta_B = 1.0-1.7 T in our single-layer samples.",
        "positive": "Comparative study of the compensated semi-metals LaBi and LuBi : A\n  first-principles approach: We have investigated the electronic structures of LaBi and LuBi, employing\nthe full-potential all electron method as implemented in Wien2k. Using this, we\nhave studied in detail both the bulk and the surface states of these materials.\nFrom our band structure calculations we find that LuBi, like LaBi, is a\ncompensated semi-metal with almost equal and sizable electron and hole pockets.\nIn analogy with experimental evidence in LaBi, we thus predict that LuBi will\nalso be a candidate for extremely large magneto-resistance (XMR), which should\nbe of immense technological interest. Our calculations reveal that LaBi,\ndespite being gapless in the bulk spectrum, displays the characteristic\nfeatures of a $\\mathbb{Z}_{2}$ topological semi-metal, resulting in gapless\nDirac cones on the surface, whereas LuBi only shows avoided band inversion in\nthe bulk and is thus a conventional compensated semi-metal with extremely large\nmagneto-resistance."
    },
    {
        "anchor": "On the possibility to observe relations between quantum measurements and\n  the entropy of phase transitions in Zn$_2$(BDC)$_2$(DABCO): The work interprets experimental data for the heat capacity of\nZn2(BDC)2(DABCO) in the region of second-order phase transitions. The proposed\nunderstanding of the processes occurring during phase transitions may be\nhelpful to reveal quantum Zeno effects in metal-organic frameworks (MOFs) with\nevolving (unstable) structural subsystems and to establish relations between\nquantum measurements and the entropy of phase transitions.",
        "positive": "High frequency magnetic behavior through the magnetoimpedance effect in\n  CoFeB/(Ta, Ag, Cu) multilayered ferromagnetic thin films: We studied the dynamics of magnetization through an investigation of the\nmagnetoimpedance effect in CoFeB/(Ta, Ag, Cu) multilayered thin films grown by\nmagnetron sputtering. Impedance measurements were analyzed in terms of the\nmechanisms responsible for their variations at different frequency intervals\nand the magnetic and structural properties of the multilayers. Analysis of the\nmechanisms responsible for magnetoimpedance according to frequency and external\nmagnetic field showed that for the CoFeB/Cu multilayer, ferromagnetic resonance\n(FMR) contributes significantly to the magnetoimpedance effect at frequencies\nclose to 470 MHz. This frequency is low when compared to the results obtained\nfor CoFeB/Ta and CoFeB/Ag multilayers and is a result of the anisotropy\ndistribution and non-formation of regular bilayers in this sample. The MImax\nvalues occurred at different frequencies according to the used non-magnetic\nmetal. Variations between 25% and 30% were seen for a localized frequency band,\nas in the case of CoFeB/Ta and CoFeB/Ag, as well as for a wide frequency range,\nin the case of CoFeB/Cu."
    },
    {
        "anchor": "Two Hydrodynamic Models of Granular Convection: We present two continuum models A and B to study the convective instability\nof granular materials subjected to vibrations. We carry out the linear\nstability analysis for model A and uncover the instability mechanism as a\nsupercritical bifurcation of a bouncing solution. We also explicitly determine\nthe onset of convection as a function of control parameters. The results of\nsimulations are in excellent agreement with the stability analysis. Additional\nfeature of the model B is the inclusion of the relaxation term in the momentum\nequation, which appears to be crucial in capturing what is missing in model A,\nin particular, in reproducing experimental convection patterns for large aspect\nratio, both vertically, in which case convective rolls move toward the surface,\nand horizontally, in which case convective rolls survive near the wall but are\nsuppressed in the bulk region.",
        "positive": "Hybrid cold and hot-wall chamber for fast synthesis of uniform graphene: We introduce a novel modality in the CVD growth of graphene which combines\nthe cold-wall and hot-wall reaction chambers. This hybrid mode preserves the\nadvantages of a cold-wall chamber as the fast growth and low fuel consumption,\nbut boosts the quality of the growth towards conventional CVD with hot-wall\nchambers. The synthesized graphene is uniform and monolayer. The electronic\ntransport measurements shows great improvements in charge carrier mobility\ncompared to graphene synthesized in a normal cold-wall reaction chamber. Our\nresults promise the development of a fast and cost-efficient growth of high\nquality graphene, suitable for scalable industrial applications."
    },
    {
        "anchor": "Modeling coupled spin and lattice dynamics: A unified model of molecular and atomistic spin dynamics is presented\nenabling simulations both in microcanonical and canonical ensembles without the\nnecessity of additional phenomenological spin damping. Transfer of energy and\nangular momentum between the lattice and the spin systems is achieved by a\ncoupling term based upon the spin-orbit interaction. The characteristic spectra\nof the spin and phonon systems are analyzed for different coupling strength and\ntemperatures. The spin spectral density shows magnon modes together with the\nuncorrelated noise induced by the coupling to the lattice. The effective\ndamping parameter is investigated showing an increase with both coupling\nstrength and temperature. The model paves the way to understanding magnetic\nrelaxation processes beyond the phenomenological approach of the Gilbert\ndamping and the dynamics of the energy transfer between lattice and spins.",
        "positive": "The influence of short range forces on melting along grain boundaries: We investigate a model which couples diffusional melting and nanoscale\nstructural forces via a combined nano-mesoscale description. Specifically, we\nobtain analytic and numerical solutions for melting processes at grain\nboundaries influenced by structural disjoining forces in the experimentally\nrelevant regime of small deviations from the melting temperature. Though\nspatially limited to the close vicinity of the tip of the propagating melt\nfinger, the influence of the disjoining forces is remarkable and leads to a\nstrong modification of the penetration velocity. The problem is represented in\nterms of a sharp interface model to capture the wide range of relevant length\nscales, predicting the growth velocity and the length scale describing the\npattern, depending on temperature, grain boundary energy, strength and length\nscale of the exponential decay of the disjoining potential. Close to\nequilibrium the short-range effects near the triple junctions can be expressed\nthrough a contact angle renormalisation in a mesoscale formulation. For higher\ndriving forces strong deviations are found, leading to a significantly higher\nmelting velocity than predicted from a purely mesoscopic description."
    },
    {
        "anchor": "Ultra-uniform Nanocrystalline Materials via Two-Step Sintering: Nanocrystalline metals and ceramics with <100 nm grain sizes and superior\nproperties (e.g., mechanical strength, hardness, fracture toughness and stored\ndielectric energy) are of great interest. Much has been discussed about\nachieving nano grains, but little is known about maintaining grain-size\nuniformity that is critical for material reliability. An especially intriguing\nquestion is whether it is possible to achieve a size distribution narrower than\nwhat Hillert[1] theoretically predicted for normal grain growth, a possibility\nsuggested, for growth with a higher growth exponent, by the generalized\nmean-field theory[2] of Lifshitz, Slyozov, Wagner (LSW)[3,4] and Hillert but\nnever realized in practice. We demonstrate that this can be achieved in bulk\nmaterials with an appropriately designed two-step sintering route that (a)\ntakes advantage of the large growth exponent in the intermediate sintering\nstage to form a most uniform microstructure despite porosity remaining, and (b)\nfreezes the grain growth thereon while continuing densification to reach full\ndensity. The resultant dense bulk Al2O3 ceramic has an average grain size of 34\nnm and a much narrower size distribution than Hillert's prediction. Bulk Al2O3\nwith a grain-size distribution narrower than the particle-size distribution of\nstarting powders was also demonstrated using this strategy, as were highly\nuniform bulk engineering metals and ceramics of either high purity and high\nmelting points (Mo and W-Re) or highly complex compositions (core-shell BaTiO3\nand 0.87BaTiO3-0.13Bi(Zn2/3(Nb0.85Ta0.15)1/3)O3).",
        "positive": "Equation of state of metallic hydrogen from Coupled Electron-Ion Monte\n  Carlo simulations: We present a study of hydrogen at pressures higher than molecular\ndissociation using the Coupled Electron-Ion Monte Carlo method. These\ncalculations use the accurate Reptation Quantum Monte Carlo method to estimate\nthe electronic energy and pressure while doing a Monte Carlo simulation of the\nprotons. In addition to presenting simulation results for the equation of state\nover a large region of phase space, we report the free energy obtained by\nthermodynamic integration. We find very good agreement with DFT calculations\nfor pressures beyond 600 GPa and densities above $\\rho=1.4 g/cm^3$. Both\nthermodynamic as well as structural properties are accurately reproduced by DFT\ncalculations. This agreement gives a strong support to the different\napproximations employed in DFT, specifically the approximate\nexchange-correlation potential and the use of pseudopotentials for the range of\ndensities considered. We find disagreement with chemical models, which suggests\na reinvestigation of planetary models, previously constructed using the\nSaumon-Chabrier-Van Horn equations of state."
    },
    {
        "anchor": "Research of X-ray induced conductivity of ZnSe sensors for their\n  application in isotopic thickness gauges: Measurements of intrinsic conductivity and X-ray induced conductivity were\nperformed on specially undopped ZnSe samples. The measurements demonstrated\nthat sensors made of ZnSe have minor intrinsic conductivity when heating up to\nthe temperature of 180 {\\deg}C, and significant X-ray induced conductivity.\nDose dependence \"dose rate - current\" is described with simple power function\nwhich considerably simplifies calibration of sensors. This results can be used\nduring the designing of high-temperature X-ray and gamma-radiation detectors\nfor radiation hot rolling thickness gauges which are widely used in the\nmetallurgy.",
        "positive": "Photocatalytic Properties of Anisotropic $\u03b2$-PtX$_2$ (X= S, Se) and\n  Janus $\u03b2$-PtSSe monolayers: The highly efficient photocatalytic water splitting to produce clean energy\nrequires novel semiconductor materials to achieve high solar-to-hydrogen energy\nconversion efficiency. Herein, the photocatalytic properties of anisotropic\n$\\beta$-PtX$_2$ (X=S, Se) and Janus $\\beta$-PtSSe monolayers are investigated\nbased on density functional theory. Small cleavage energy for \\{beta}-PtS2\n(0.44 J/m2) and $\\beta$-PtSe$_2$ (0.40 J/m$^2$) endorses the possibility of\ntheir mechanical exfoliation from respective layered bulk material. The\ncalculated results find \\{beta}-PtX2 monolayers to have an appropriate bandgap\n(~1.8-2.6 eV) enclosing the water redox potential, light absorption\ncoefficients (~104 cm$^{-1}$), and excitons binding energy (~0.5-0.7 eV), which\nfacilitates excellent visible-light driven photocatalytic performance.\nRemarkably, an inherent structural anisotropy leads to the anisotropic and high\ncarrier mobility (up to ~5 x 10$^3$ cm$^2$ V$^{-1}$ S$^{-1}$) leading to fast\ntransport of photogenerated carriers. Notably, the small required external\npotential to derive hydrogen evolution reaction and oxygen evolution reaction\nprocesses with an excellent solar-to-hydrogen energy conversion efficiency of\n$\\beta$-PtSe$_2$ (~16%) and $\\beta$-PtSSe (~18%) makes them promising\ncandidates for solar water splitting applications."
    },
    {
        "anchor": "Averting the infrared catastrophe in the gold standard of quantum\n  chemistry: Coupled-cluster theories can be used to compute ab initio electronic\ncorrelation energies of real materials with systematically improvable accuracy.\nHowever, the widely-used coupled cluster singles and doubles plus perturbative\ntriples (CCSD(T)) method is only applicable to insulating materials. For\nzero-gap materials the truncation of the underlying many-body perturbation\nexpansion leads to an infrared catastrophe. Here, we present a novel\nperturbative triples formalism that yields convergent correlation energies in\nmetallic systems. Furthermore, the computed correlation energies for the three\ndimensional uniform electron gas at metallic densities are in good agreement\nwith quantum Monte Carlo results. At the same time the newly proposed method\nretains all desirable properties of CCSD(T) such as its accuracy for insulating\nsystems as well as its low computational cost compared to a full inclusion of\nthe triples. This paves the way for ab initio calculations of real metals with\nchemical accuracy.",
        "positive": "Phonon-phonon coupling in bismuth vanadate over a large temperature\n  range across the monoclinic phase: In this work we study phonon-phonon coupling in bismuth vanadate (BiVO4),\nknown for its second-order transition involving a variety of coupling\nmechanisms. Using Raman spectroscopy as a probe, we identify two optical\ncoupled phonon modes of the VO4 tetrahedron and study them by varying light\npolarization and temperature. The coupling manifests in non-Lorentzian\nline-shapes of Raman peaks and frequency shifts. We use theoretical framework\nof coupled damped harmonic oscillators to model the coupling and capture the\nphenomena in the temperature evolution of the coupling parameters. The coupling\nis negligible at temperatures below 100 K and later increases in magnitude with\ntemperature until 400 K. The sign of the coupling parameter depends on the\nlight polarization direction, causing either phonon attraction or repulsion.\nAfter 400 K the phonon-phonon coupling diminishes when approaching phase\ntransition at which the phonon modes change their symmetry and the coupling is\nno longer allowed."
    },
    {
        "anchor": "Implementation of an all-electron GW Approximation using the Projector\n  Augmented Wave method: I. Formulation and application to the electronic\n  structure of semiconductors: We have implemented the so called GW approximation (GWA) based on an\nall-electron full-potential Projector Augmented Wave (PAW) method. For the\nscreening of the Coulomb interaction W we tested three different plasmon-pole\ndielectric function models, and showed that the accuracy of the quasiparticle\nenergies is not sensitive to the the details of these models. We have then\napplied this new method to compute the quasiparticle band structure of some\nsmall, medium and large-band-gap semiconductors: Si, GaAs, AlAs, InP, SiMg$_2$,\nC and (insulator) LiCl. A special attention was devoted to the convergence of\nthe self-energy with respect to both the {\\bf k}-points in the Brillouin zone\nand to the number of reciprocal space $\\bf G$-vectors. The most important\nresult is that although the all-electron GWA improves considerably the\nquasiparticle band structure of semiconductors, it does not always provide the\ncorrect energy band gaps as originally claimed by GWA pseudopotential type of\ncalculations. We argue that the decoupling between the valence and core\nelectrons is a problem, and is some what hidden in a pseudopotential type of\napproach.",
        "positive": "Probing oppositely charged surfactant and copolymer interactions by\n  isothermal titration microcalorimetry: The complexation between charged-neutral block copolymers and oppositely\ncharged surfactants was investigated by light scattering experiments and by\nisothermal titration calorimetry (ITC). The copolymer was poly(sodium\nacrylate)-b-poly(acrylamide) and the surfactant dodecyltrimethylammonium\nbromide (DTAB). In a previous report, we had shown that the copolymers and the\nsurfactants co-assembled spontaneously into colloidal complexes. Depending of\nthe charge ratio Z = [DTA+]/[COO-], the complexes were either single surfactant\nmicelles decorated by copolymers, or core-shell hierarchical structures. ITC\nwas performed in order to investigate the thermodynamics of the complex\nformation. Titrations of copolymers by surfactants and of surfactants by\ncopolymers revealed that the electrostatic co-assembly was an endothermic\nreaction, suggesting a process dominated by the entropy of the counterions.\nHere we found that the thermodynamic quantities associated with the reaction\ndepended on the mixing order. When surfactants were added stepwise to\ncopolymers, the titration was associated with the formation of single micelles\ndecorated by a unique polymer. Above a critical charge ratio, the micelles\nrearranged themselves into 100 nm colloidal complexes in a collective process\nwhich displayed the following features : i) the process was very slow as\ncompared to the timescale of Brownian diffusion, ii) the thermodynamic\nsignature was a endothermic peak and iii) the stoichiometry between the\npositive and negative charges was modified from n = 0.48 (single micelles) to\n0.75 (core-shell complexes). The amount of polyelectrolytes needed for the\ncomplex formation exceeded the number required to compensate the net micellar\ncharge, confirming the evidence of overcharging in the complex formation."
    },
    {
        "anchor": "Tunability and Losses of Mid-infrared Plasmonics in Heavily Doped\n  Germanium Thin Films: Heavily-doped semiconductor films are very promising for application in\nmid-infrared plasmonic devices because the real part of their dielectric\nfunction is negative and broadly tunable in this wavelength range. In this work\nwe investigate heavily n-type doped germanium epilayers grown on different\nsubstrates, in-situ doped in the $10^{17}$ to $10^{19}$ cm$^{-3}$ range, by\ninfrared spectroscopy, first principle calculations, pump-probe spectroscopy\nand dc transport measurements to determine the relation between plasma edge and\ncarrier density and to quantify mid-infrared plasmon losses. We demonstrate\nthat the unscreened plasma frequency can be tuned in the 400 - 4800 cm$^{-1}$\nrange and that the average electron scattering rate, dominated by scattering\nwith optical phonons and charged impurities, increases almost linearly with\nfrequency. We also found weak dependence of losses and tunability on the\ncrystal defect density, on the inactivated dopant density and on the\ntemperature down to 10 K. In films where the plasma was optically activated by\npumping in the near-infrared, we found weak but significant dependence of\nrelaxation times on the static doping level of the film. Our results suggest\nthat plasmon decay times in the several-picosecond range can be obtained in\nn-type germanium thin films grown on silicon substrates hence allowing for\nunderdamped mid-infrared plasma oscillations at room temperature.",
        "positive": "Multi-scale energy homogenization for 3D printed microstructures with a\n  Diritchlet boundary condition relaxation under plastic deformation: The present work is a proof of concept of the capabilities of paralellization\nin the calculation of metamaterials in a non-linear regime. In this work we\nsubdivided the bulk material into subregions where the mechanical properties\nare homogenized energetically. We demonstrate that the calculation can be\nsubdivided to save RAM memory and fit the local non-linear behaviour of the\nmetamaterial. This methodology has the potentiality to be implemented in the\nparallelization of those calculations, where the right estimation of the energy\nof the local processes at every step is important."
    },
    {
        "anchor": "Magnetic Roughness and Domain Correlations in Antiferromagnetically\n  Coupled Multilayers: The in-plane correlation lengths and magnetic disorder of magnetic domains in\na transition metal multilayer have been studied using neutron scattering\ntechniques. A new theoretical framework is presented connecting the observed\nscattering to the in-plane correlation length and the dispersion of the local\nmagnetization vector about the mean macroscopic direction. The results\nunambiguously show the highly correlated nature of the antiferromagnetically\ncoupled domain structure vertically throughout the multilayer. We are easily\nable to relate the neutron determined magnetic dispersion and domain\ncorrelations to magnetization and magnetotransport experiments.",
        "positive": "Topological Phase Transition in a Magnetic Weyl Semimetal: Topological Weyl semimetals (TWSs) are exotic crystals possessing emergent\nrelativistic Weyl fermions connected by unique surface Fermi-arcs (SFAs) in\ntheir electronic structures. To realize the TWS state, certain symmetry (such\nas the inversion or time reversal symmetry) must be broken, leading to a\ntopological phase transition (TPT). Despite the great importance in\nunderstanding the formation of TWSs and their unusual properties, direct\nobservation of such a TPT has been challenging. Here, using a recently\ndiscovered magnetic TWS Co3Sn2S2, we were able to systematically study its TPT\nwith detailed temperature dependence of the electronic structures by\nangle-resolved photoemission spectroscopy. The TPT with drastic band structures\nevolution was clearly observed across the Curie temperature (TC = 177 K),\nincluding the disappearance of the characteristic SFAs and the recombination of\nthe spin-split bands that leads to the annihilation of Weyl points with\nopposite chirality. These results not only reveal important insights on the\ninterplay between the magnetism and band topology in TWSs, but also provide a\nnew method to control their exotic physical properties."
    },
    {
        "anchor": "Comparison of long-range corrected kernels and range-separated hybrids\n  for excitons in solids: The most accurate theoretical method to describe excitons is the solution of\nthe Bethe-Salpeter equation in the GW approximation (GW-BSE). However, because\nof its computation cost, time-dependent density functional theory (TDDFT) is\nbecoming the alternative approach to GW-BSE to describe excitons in solids.\nNowadays, the most efficient strategy to describe optical spectra of solids in\nTDDFT is to use long-range corrected exchange-correlation kernels on top of GW\nor scissor-corrected energies. In recent years, a different strategy based on\nrange-separated hybrid functionals started to be developed in the framework of\ntime-dependent generalised Kohn-Sham density functional theory (TDGKSDFT).\nHere, we compare the performance of long-range corrected kernels with\nrange-separated hybrid functionals for the description of excitons in solids.\nThis comparison has the purpose to weight the pros and cons of using\nrange-separated hybrid functionals, giving new perspectives for theoretical\ndevelopments of these functionals. We illustrate the comparison for the case of\nSi and LiF, representative of solid state excitons.",
        "positive": "New Results for the Nonlocal Kardar-Parisi-Zhang Equation: In this paper various predictions for the scaling exponents of the Nonlocal\nKardar-Parisi-Zhang (NKPZ) equation are discussed. I use the Self-Consistent\nExpansion (SCE), and obtain results that are quite different from result\nobtained in the past, using Dynamic Renormalization Group analysis (DRG), a\nScaling Approach (SA) and a self-consistent Mode Coupling approach (MC). It is\nshown that the results obtained using SCE recover an exact result for a\nsubfamily of the NKPZ models in one dimension, while all the other methods fail\nto do so. It is also shown that the SCE result is the only one that is\ncompatible with simple observations on the dependence of the dynamic exponent\n$z$ in the NKPZ model on the exponent $\\rho$ characterizing the decay of the\nnonlinear interaction. The reasons for the failure of other methods to deal\nwith NKPZ are also discussed."
    },
    {
        "anchor": "Phase field crystal modeling of early stage precipitation and clustering: A phase field crystal model is used to investigate the mechanisms of\nformation and growth of early clusters in quenched/aged dilute binary alloys, a\nphenomenon typically outside the scope of molecular dynamics time scales. We\nshow that formation of early sub-critical clusters is triggered by the stress\nrelaxation effect of quenched-in defects, such as dislocations, on the energy\nbarrier and the critical size for nucleation. In particular, through analysis\nof system energetics, we demonstrate that the growth of sub-critical clusters\ninto overcritical sizes occurs due to the fact that highly strained areas in\nthe lattice locally reduce or even eliminate the free energy barrier for a\nfirst-order transition.",
        "positive": "High-strain-induced local modification of the electronic properties of\n  VO$_2$ thin films: Vanadium dioxide (VO2) is a popular candidate for electronic and optical\nswitching applications due to its well-known semiconductor-metal transition.\nIts study is notoriously challenging due to the interplay of long and short\nrange elastic distortions, as well as the symmetry change, and the electronic\nstructure changes. The inherent coupling of lattice and electronic degrees of\nfreedom opens the avenue towards mechanical actuation of single domains. In\nthis work, we show that we can manipulate and monitor the reversible\nsemiconductor-to-metal transition of VO2 while applying a controlled amount of\nmechanical pressure by a nanosized metallic probe using an atomic force\nmicroscope. At a critical pressure, we can reversibly actuate the phase\ntransition with a large modulation of the conductivity. Direct tunneling\nthrough the VO2-metal contact is observed as the main charge carrier injection\nmechanism before and after the phase transition of VO2. The tunneling barrier\nis formed by a very thin but persistently insulating surfacelayer of the VO2.\nThe necessary pressure to induce the transition decreases with temperature. In\naddition, we measured the phase coexistence line in a hitherto unexplored\nregime. Our study provides valuable information on pressure-induced electronic\nmodifications of the VO2 properties, as well as on nanoscale metal-oxide\ncontacts, which can help in the future design of oxide electronics."
    },
    {
        "anchor": "Compact representation of one-particle wavefunctions and scalar fields\n  obtained from electronic-structure calculations: We present a code-independent compact representation of one-electron\nwavefunctions and other volumetric data (electron density, electrostatic\npotential, etc.) produced by electronic-structure calculations. The compactness\nof the representation insures minimization of digital storage requirements for\nthe computational data, while the code-independence makes the data ready for\n\"big data\" analytics. Our approach allows to minimize differences between\noriginal and the new representation, and is in principle information-lossless.\nThe procedure for obtaining the wavefunction representation is closely related\nto construction of natural atomic orbitals, and benefits from the localization\nof Wannier functions. Thus, our approach fits perfectly any infrastructure\nproviding a code-independent tool set for electronic-structure data analysis.",
        "positive": "Electronic Structure of Monolayer and Bilayer Black Phosphorus with\n  Charged Defects: We use an atomistic approach to study the electronic properties of monolayer\nand bilayer black phosphorus in the vicinity of a charged defect. In\nparticular, we combine screened defect potentials obtained from\nfirst-principles linear response theory with large-scale tight-binding\nsimulations to calculate the wavefunctions and energies of bound acceptor and\ndonor states. As a consequence of the anisotropic band structure, the defect\nstates in these systems form distorted hydrogenic orbitals with a different\nordering than in isotropic materials. For the monolayer, we study the\ndependence of the binding energies of charged adsorbates on the defect height\nand the dielectric constant of a substrate in an experimental setup. We also\ncompare our results to an anisotropic effective mass model and find\nquantitative and qualitative differences when the charged defect is close to\nthe black phosphorus or when the screening from the substrate is weak. For the\nbilayer, we compare results for charged adsorbates and charged intercalants and\nfind that intercalants induce more prominent secondary peaks in the local\ndensity of states because they interact strongly with electronic states on both\nlayers. These new insights can be directly tested in scanning tunneling\nspectroscopy measurements and enable a detailed understanding of the role of\nCoulomb impurities in electronic devices."
    },
    {
        "anchor": "Fractal dimension and size scaling of domains in thin films of\n  multiferroic BiFeO3: We have analyzed the morphology of ferroelectric domains in very thin films\nof multiferroic BiFeO3. Unlike the more common stripe domains observed in\nthicker films BiFeO3 or in other ferroics, the domains tend not to be straight,\nbut irregular in shape, with significant domain wall roughening leading to a\nfractal dimensionality. Also contrary to what is usually observed in other\nferroics, the domain size appears not to scale as the square root of the film\nthickness. A model is proposed in which the observed domain size as a function\nof film thickness can be directly linked to the fractal dimension of the\ndomains.",
        "positive": "Multiscale Modeling of Shock Wave Localization in Porous Energetic\n  Material: Shock wave interactions with defects, such as pores, are known to play a key\nrole in the chemical initiation of energetic materials. The shock response of\nhexanitrostilbene is studied through a combination of large scale reactive\nmolecular dynamics and mesoscale hydrodynamic simulations. In order to extend\nour simulation capability at the mesoscale to include weak shock conditions (<\n6 GPa), atomistic simulations of pore collapse are used to define a strain rate\ndependent strength model. Comparing these simulation methods allows us to\nimpose physically-reasonable constraints on the mesoscale model parameters. In\ndoing so, we have been able to study shock waves interacting with pores as a\nfunction of this viscoplastic material response. We find that the pore collapse\nbehavior of weak shocks is characteristically different to that of strong\nshocks."
    },
    {
        "anchor": "Wave propagation in non-centrosymmetric beam-lattices with lumped\n  masses: discrete and micropolar modelling: The in-plane acoustic behavior of non-centrosymmetric lattices having nodes\nendowed with mass and gyroscopic inertia and connected by massless ligaments\nwith asymmetric elastic properties has been analysed through a discrete model\nand a continuum micropolar model. In the first case the propagation of harmonic\nwaves and the dispersion functions have been obtained by the discrete\nFloquet-Bloch approach. It is shown that the optical branch departs from a\ncritical point with vanishing group velocity and for the considered cases this\nbranch is decreasing for increasing the norm of the wave vector from the long\nwave limit. A micropolar continuum model, useful to approximate the discrete\nmodel, has been derived through a continualization method based on a\ndown-scaling law based on a second-order Taylor expansion of the generalized\nmacro-displacement field. It is worth noting that the second order elasticity\ntensor coupling curvatures and micro-couples turns out to be negative defined\nalso in the general case of non-centrosymmetric lattice. The eigenvalue problem\ngoverning the harmonic propagation in the micropolar non-centrosymmetric\ncontinuum results in general characterized by a hermitian full matrix that is\nexact up to the second order in the wave vector. Examples concerning square and\nequilateral triangular lattices and their acoustic properties have been\nanalysed from both the exact Lagrangian model (within the assumed hypotheses)\nand the micropolar approximate model. Finally, in consideration of the negative\ndefiniteness of the second order elastic tensor of the micropolar model, the\nloss of strong hyperbolicity of the equation of motion has been investigated.",
        "positive": "Origin of Hinge-Like Mechanism in Single-Layer Black Phosphorus: the\n  Angle-Angle Cross Interaction: The single-layer black phosphorus is characteristic for its puckered\nconfiguration that possesses the hinge-like mechanism, which leads to the\nhighly anisotropic in-plane Poisson's ratios and the negative out-of-plane\nPoisson's ratio. We reveal that the hinge-like mechanism can be attributed to\nthe angle-angle cross interaction, which, combined with the bond stretching and\nangle bending interactions, is able to provide a good description of the\nmechanical properties in the single-layer black phosphorus. We also propose a\nnonlinear angle-angle cross interaction, which follows the form of the\nStillinger-Weber potential and is advantageous for molecular dynamics\nsimulations of single-layer black phosphorous under large deformations."
    },
    {
        "anchor": "Phase retrieval for Bragg coherent diffraction imaging at high X-ray\n  energies: Coherent X-ray beams with energies $\\geq 50$ keV can potentially enable\nthree-dimensional imaging of atomic lattice distortion fields within individual\ncrystallites in bulk polycrystalline materials through Bragg coherent\ndiffraction imaging (BCDI). However, the undersampling of the diffraction\nsignal due to Fourier space compression at high X-ray energies renders\nconventional phase retrieval algorithms unsuitable for three-dimensional\nreconstruction. To address this problem we utilize a phase retrieval method\nwith a Fourier constraint specifically tailored for undersampled diffraction\ndata measured with coarse-pitched detector pixels that bin the underlying\nsignal. With our approach, we show that it is possible to reconstruct\nthree-dimensional strained crystallites from an undersampled Bragg diffraction\ndata set subject to pixel-area integration without having to physically\nupsample the diffraction signal. Using simulations and experimental results, we\ndemonstrate that explicit modeling of Fourier space compression during phase\nretrieval provides a viable means by which to invert high-energy BCDI data,\nwhich is otherwise intractable.",
        "positive": "Prediction of a new potential high-pressure structure of FeSiO$_3$: We predict a new candidate high-temperature high-pressure structure of\nFeSiO$_3$ with space-group symmetry Cmmm by applying an evolutionary algorithm\nwithin DFT+U that we call post-perovskite II (PPv-II). An exhaustive search\nfound no other competitive candidate structures with ABO$_3$ composition. We\ncompared the X-ray diffraction (XRD) pattern of FeSiO$_3$ PPv-II with\nexperimental results of the recently reported H-phase of (Fe,Mg)SiO$_3$. The\nintensities and positions of two main X-ray diffraction peaks of PPv-II\nFeSiO$_3$ compare well with those of the H-phase. We also calculated the static\nequation of state, the enthalpy and the bulk modulus of the PPv-II phase and\ncompared it with those of perovskite (Pv) and post-perovskite (PPv) phases of\nFeSiO$_3$. According to the static DFT+U computations the PPv-II phase of\nFeSiO$_3$ is less stable than Pv and PPv phases under lower mantle pressure\nconditions at 0 K and has a higher volume. PPv-II may be entropically\nstabilized, and may be a stable phase in Earth$'$s lower mantle, coexisting\nwith $\\alpha$-PbO$_2$ (Columbite-structured) silica and perovskite, or with\nmagnesiowustite or ferropericlase, depending on bulk composition."
    },
    {
        "anchor": "Liquid-liquid transition in supercooled silicon determined by\n  first-principles simulation: First principles molecular dynamics simulations reveal a liquid-liquid phase\ntransition in supercooled elemental silicon. Two phases coexist below\n$T_c\\approx 1232K$. The low density phase is nearly tetra-coordinated, with a\npseudogap at the Fermi surface, while the high density phase is more highly\ncoordinated and metallic in nature. The transition is observed through the\nformation of van der Waals loops in pressure-volume isotherms below $T_c$.",
        "positive": "Relaxors, spin-, Stoner- and cluster-glasses: It is argued that the main characteristic features of displacive relaxor\nferrolectrics of the form ${\\rm{A(B,B')}\\rm{O}}_3$ with isovalent ${\\rm{B,B'}}$\ncan be explained and understood in terms of a soft-pseudospin analogue of\nconventional spin glasses as extended to itinerant magnet systems. The emphasis\nis on conceptual comprehension and on stimulating new perspectives with respect\nto previous and future studies. Some suggestions are made for further studies\nboth on actual real systems and on test model systems to probe further. The\ncase of heterovalent systems is also considered briefly."
    },
    {
        "anchor": "Role of anisotropy in determining stability of electrodeposition at\n  solid-solid interfaces: We investigate the stability of electrodeposition at solid-solid interfaces\nfor materials exhibiting an anisotropic mechanical response. The stability of\nelectrodeposition or resistance to the formation of dendrites is studied within\na linear stability analysis. The deformation and stress equations are solved\nusing the Stroh formalism and faithfully recover the boundary conditions at the\ninterface. The stability parameter is used to quantify the stability of\ndifferent solid-solid interfaces incorporating the full anisotropy of the\nelastic tensor of the two materials. Results show a high degree of variability\nin the stability parameter depending on the crystallographic orientation of the\nsolids in contact, and point to opportunities for exploiting this effect in\ndeveloping Li metal anodes.",
        "positive": "Thermodynamic properties of liquid mercury to 520 K and 7 GPa from\n  acoustic velocity measurements: Ultrafast acoustics measurements on liquid mercury have been performed at\nhigh pressure and temperature in diamond anvils cell using picosecond acoustic\ninterferometry. We extract the density of mercury from adiabatic sound\nvelocities using a numerical iterative procedure. The pressure and temperature\ndependence of the thermal expansion, the isothermal compressibilty, the\nisothermal bulk modulus and its pressure derivative are derived up to 7 GPa and\n520 K. In the high pressure regime, the sound velocity values, at a given\ndensity, are shown to be only slightly dependent on the specific temperature\nand pressure conditions. The density dependence of sound velocity at low\ndensity is consistent with that observed with our data at high density in the\nmetallic liquid state."
    },
    {
        "anchor": "Ultrafast relaxation of symmetry-breaking photo-induced atomic forces: We present a first-principles method for the calculation of the\ntemperature-dependent relaxation of symmetry-breaking atomic driving forces in\nphotoexcited systems. We calculate the phonon-assisted decay of the\nphotoexcited force on the low-symmetry $E_g$ mode following absorption of an\nultrafast pulse in the prototypical group-V semimetals, Bi, Sb and As. The\nforce decay lifetimes for Bi and Sb are of the order of $10$ fs and in good\nagreement with recent experiments, demonstrating that electron-phonon\nscattering is the dominant mechanism relaxing the symmetry-breaking forces.\nCalculations for a range of absorbed photon energies suggest that larger\namplitude, symmetry-breaking atomic motion may be induced by choosing a pump\nphoton energy which maximises the product of the initial $E_g$ force and its\nlifetime. We also find that the high-symmetry $A_{1g}$ force undergoes a\npartial decay to a non-zero constant on similar timescales, which has not yet\nbeen measured in experiments. We observe that the imaginary part of the\nelectron self-energy, averaged over the photoexcited carrier distribution,\nprovides a reasonable estimate for the decay rate of symmetry-breaking forces.",
        "positive": "Algorithm for distance list extraction from pair distribution functions: We present an algorithm to extract the distance list from atomic pair\ndistribution functions (PDFs) in a highly automated way. The algorithm is\nconstructed via curve fitting based on a Debye scattering equation model. Due\nto the non-convex nature of the resulting optimization problem, a number of\ntechniques are developed to overcome various computational difficulties. A key\ningredient is a new approach to obtain a reasonable initial guess based on the\ntheoretical properties of the mathematical model. Tests on various\nnanostructured samples show the effectiveness of the initial guess and the\naccuracy and overall good performance of the extraction algorithm. This\napproach could be extended to any spectrum that is approximated as a sum of\nGaussian functions."
    },
    {
        "anchor": "Dynamical local connector approximation for electron addition and\n  removal spectra: Realistic calculations of electron addition and removal spectra rely most\noften on Green's functions and complex, non-local self-energies. We introduce a\nshortcut to obtain the spectral function directly from a local and\nfrequency-dependent, yet real, potential. We calculate this potential in the\nhomogeneous electron gas (HEG), and we design a connector which prescribes the\nuse of the HEG results to calculate spectral functions of real materials.\nBenchmark results for several solids demonstrate the potential of our approach.",
        "positive": "Numerical Simulation of Magnetic Interactions in Polycrystalline YFeO3: The magnetic behavior of polycrystalline yttrium orthoferrite was studied\nfrom the experimental and theoretical points of view. Magnetization\nmeasurements up to 170 kOe were carried out on a single-phase YFeO3 sample\nsynthesized from heterobimetallic alkoxides. The complex interplay between\nweak-ferromagnetic and antiferromagnetic interactions, observed in the\nexperimental M(H) curves, was successfully simulated by locally minimizing the\nmagnetic energy of two interacting Fe sublattices. The resulting values of\nexchange field (H_E = 5590 kOe), anisotropy field (H_A = 0.5 kOe) and\nDzyaloshinsky-Moriya antisymmetric field (H_D = 149 kOe) are in good agreement\nwith previous reports on this system."
    },
    {
        "anchor": "Passivity of Metals: Potential-Step Transients for Passive Current\n  Density and Barrier Layer Thickness in the Point Defect Model: In an earlier pre-print we developed a variant of the point defect model that\ncorrected a flaw in one of the defect reactions and to be specific reaction 3\nof the original point defect model was replaced by reaction 3prime of the\nvariant. Here we apply the corrected model to find the time evolution of the\npassive current density and the barrier layer thickness. Though the functional\nforms agree with the forms reported earlier by Macdonald and co-workers, the\ncomposition of the parameters differ significantly. This explains the\nexperimental success of the flawed model. This semblance is also manifested in\nthe diagnostics for the current transient involving the time-derivative of the\ncurrent density. The present theory will be useful for the correct analysis of\ntransients which result from switching the potential in the anodic or cathodic\ndirection from an initial steady state.",
        "positive": "Enhancement of valley polarization at high photoexcited densities in\n  MoS2 monolayers: We have investigated the steady-sate valley polarization and valley coherence\nof encapsulated MoS2 monolayer as a function of the temperature and the power\ndensity with a continuous wave laser excitation. Both valley polarization and\ncoherence exhibit a non-monotonic dependence on sample temperature, attaining a\nlocal maximum at T=40 K. This has been recently attributed to a motional\nnarrowing effect: an enhancement of the valley relaxation time occurs when the\nscattering rate increases. At a fixed temperature of T=6 K, a two-fold increase\nof the steady-state valley polarization is achieved by increasing the laser\nexcitation power, which we attribute to a local heating induced by the energy\nrelaxation of photoexcited excitons outside the light cone and to an increase\nin the exciton-exciton scattering rate. In contrast, in the same power range\nonly a moderate enhancement of valley coherence is observed. Further increasing\nthe excitation power leads to a small reduction of valley polarization but a\ndramatic loss of valley coherence. Supported by spatial imaging of the\nexcitonic luminescence and polarization, we attribute this behaviour to the\ndetrimental role of exciton-exciton interactions on the pure dephasing rate."
    },
    {
        "anchor": "Sub-picosecond photo-induced displacive phase transition in\n  two-dimensional MoTe$_2$: Photo-induced phase transitions (PIPTs) provide an ultrafast,\nenergy-efficient way for precisely manipulating the topological properties of\ntransition-metal ditellurides, and can be used to stabilize a topological phase\nin an otherwise semiconducting material. Using first-principles calculations,\nwe demonstrate that the PIPT in monolayer MoTe$_2$ from the semiconducting 2H\nphase to the topological 1T$'$ phase can be triggered purely by electronic\nexcitations that soften multiple lattice vibrational modes. These softenings,\ndriven by a Peierls-like mechanism within the conduction bands, lead to\nstructural symmetry breaking within sub-picosecond timescales, which is shorter\nthan the timescale of a thermally driven phase transition. The transition is\npredicted to be triggered by photons with energies over $1.96$\\,eV, with an\nassociated excited carrier density of $3.4\\times10^{14}$\\,cm$^{-2}$, which\nenables a controllable phase transformation by varying the laser wavelength.\nOur results provide insight into the underlying physics of the phase transition\nin 2D transition-metal ditellurides, and show an ultrafast phase transition\nmechanism for manipulation of the topological properties of 2D systems.",
        "positive": "Low-Dimensional Conduction Mechanisms in Highly Conductive and\n  Transparent Conjugated Polymers: Electronic conduction in conjugated polymers is of emerging technological\ninterest for high-performance optoelectronic and thermoelectric devices. A\ncompletely new aspect and understanding of the conduction mechanism on\nconducting polymers is introduced, allowing the applicability of materials to\nbe optimized. The charge-transport mechanism is explained by direct\nexperimental evidence with a very well supported theoretical model."
    },
    {
        "anchor": "Mass uptake during oxidation of metallic alloys: literature data\n  collection, analysis, and FAIR sharing: The area-normalized change of mass ($\\Delta$m/A) with time during the\noxidation of metallic alloys is commonly used to assess oxidation resistance.\nAnalyses of such data can also aid in evaluating underlying oxidation\nmechanisms. We performed an exhaustive literature search and digitized\nnormalized mass change vs. time data for 407 alloys. To maximize the impact of\nthese and future mass uptake data, we developed and published an open, online,\ncomputational workflow that fits the data to various models of oxidation\nkinetics, uses Bayesian statistics for model selection, and makes the raw data\nand model parameters available via a queryable database. The tool, Refractory\nOxidation Database (https://nanohub.org/tools/refoxdb/), uses nanoHUB's Sim2Ls\nto make the workflow and data (including metadata) findable, accessible,\ninteroperable, and reusable (FAIR). We find that the models selected by the\noriginal authors do not match the most likely one according to the Bayesian\ninformation criterion (BIC) in 71% of the cases. Further, in 56% of the cases,\nthe published model was not even in the top 3 models according to the BIC.\nThese numbers were obtained assuming an experimental noise of 2.5% of the mass\ngain range, a smaller noise leads to more discrepancies. The RefOxDB tool is\nopen access and researchers can add their own raw data (those to be included in\nfuture publications, as well as negative results) for analysis and to share\ntheir work with the community. Such consistent and systematic analysis of open,\ncommunity generated data can significantly accelerate the development of\nmachine-learning models for oxidation behavior and assist in the understanding\nand improvement of oxidation resistance.",
        "positive": "Finite-size effects on the dynamic susceptibility of CoPhOMe\n  single-chain molecular magnets in presence of a static magnetic field: The static and dynamic properties of the single-chain molecular magnet\n[Co(hfac)$_2$NITPhOMe] are investigated in the framework of the Ising model\nwith Glauber dynamics, in order to take into account both the effect of an\napplied magnetic field and a finite size of the chains. For static fields of\nmoderate intensity and short chain lengths, the approximation of a\nmono-exponential decay of the magnetization fluctuations is found to be valid\nat low temperatures; for strong fields and long chains, a multi-exponential\ndecay should rather be assumed. The effect of an oscillating magnetic field,\nwith intensity much smaller than that of the static one, is included in the\ntheory in order to obtain the dynamic susceptibility $\\chi(\\omega)$. We find\nthat, for an open chain with $N$ spins, $\\chi(\\omega)$ can be written as a\nweighted sum of $N$ frequency contributions, with a sum rule relating the\nfrequency weights to the static susceptibility of the chain. Very good\nagreement is found between the theoretical dynamic susceptibility and the ac\nsusceptibility measured in moderate static fields ($H_{\\rm dc}\\le 2$ kOe),\nwhere the approximation of a single dominating frequency turns out to be valid.\nFor static fields in this range, new data for the relaxation time, $\\tau$\nversus $H_{\\rm dc}$, of the magnetization of CoPhOMe at low temperature are\nalso well reproduced by theory, provided that finite-size effects are included."
    },
    {
        "anchor": "Study of the charge profile of thermally poled electrets: The charge profile of thermally poled electrets has been studied using two\ndifferent methods, laser induced pressure pulse (LIPP) and pulsed\nelectroacoustic (PEA), to gain insight into the mechanisms that are activated\nand assess which is the most appropriate method to study the charge profile.\nDisc--shaped PET samples have been conventionally poled to activate both the\nalpha and the rho relaxation and, right after, partially discharged up to a\ntemperature Tpd. In this way, samples with a different combination of dipolar\nand space charge polarization have been obtained. Both LIPP and PEA reveal\nasymmetric profiles for Tpd below the glass transition temperature, that\nprogressively become antisymmetric for higher temperatures. The shape and\nevolution of the charge profiles can be explained assuming injection of\nnegative carriers from the anode that enhances the trapping of positive\ncarriers near this electrode. It can be observed that PEA is able to detect a\nwider variety of polarization mechanisms in the system while LIPP gives a\nsimpler picture of the charge profile.",
        "positive": "Improved model for the thermal conductivity of binary metallic systems: We extended and corrected Mott's two-band model for the\ncomposition-dependence of thermal and electrical conductivity in binary metal\nalloys based on high-throughput time-domain thermoreflectance (TDTR)\nmeasurements on diffusion multiples and scatterer-density calculations from\nfirst principles. Examining PdAg, PtRh, AuAg, AuCu, PdCu, PdPt, and NiRh binary\nalloys, we found that the nature of the two dominant scatterer-bands considered\nin the Mott model changes with the alloys, and should be interpreted as a\ncombination of the dominant element-specific s- and/or d-orbitals. Using\ncalculated orbital and element-resolved density-of-states values calculated\nwith density functional theory as input, we determined the correct orbital mix\nthat dominates electron scattering for all examined alloys and find excellent\nagreement between fitted models and experiments. The proposed description of\nthe composition dependence of the resistivity can be readily implemented into\nthe CALPHAD framework."
    },
    {
        "anchor": "Structural, dielectric, electrocaloric, and energy storage properties of\n  lead free Ba$_{0.975}$La$_{0.017}$(ZrxTi$_{0.95-x}$)Sn$_{0.05}$O$_3$ (x =\n  0.05; 0.20) ceramics: A-site deficient Ba$_{0.975}$La$_{0.017}$(ZrxTi$_{0.95-x}$)Sn$_{0.05}$O$_3$\n(x = 0.05; 0.20) ceramics (BLaZ100xTS) were synthesized using the solid-state\nreaction. The microstructural study revealed a high density and low porosity in\nthe studied ceramics. Besides, grain size lower than 1.5 micrometer was\nobserved in the studied compounds, which is due to the incorporation of the\nrare earth element (lanthanum). X-ray diffraction and Raman studies revealed\nthat BLaZ5TS and BLaZ20TS crystallize in a perovskite-type structure with\ntetragonal and cubic symmetry, respectively. The dielectric study showed a\nnormal ferroelectric-paraelectric phase transition for BLaZ5TS while a diffuse\nphase transition is noticed for BLaZ20TS sample. The energy-storage density and\nthe associated energy efficiency were determined from the P-E loops versus\ntemperature and the calculated values are comparable with results obtained on\nBCZT systems. Furthermore, the adiabatic temperature change (Delta)T was\ncalculated through the indirect method and a relatively high value of\n(Delta)T/(Delta)E = 0.2 10-6 K m/V is obtained in BLaZ5TS system. The\nsimultaneous presence of energy storage property and electrocaloric\nresponsivity makes this system a promising environmentally friendly candidate\nfor application in electronic devices.",
        "positive": "Frequency dependent dielectric properties of Al/ maleic anhydride (MA)\n  /p-Si structures: Al/ maleic anhydride (MA) /p-Si organic Schottky devices were fabricated on a\np-Si semiconductor wafer by spin coating. The frequency and voltage dependent\ndielectric constant of Al/MA/p-Si have been investigated. Dielectric properties\nand electrical conductivity of contact structures have been investigated in\ndetail by using spectroscopic technique in a wide range of frequencies and\napplied bias voltages at room temperature. The values of dielectric constant,\ndielectric loss, dielectric loss tangent, real and imaginary parts of the\nelectrical modulus and ac electrical conductivity were found considerably\nsensitive to frequency and applied bias voltage especially in depletion and\naccumulation regions. Experimental results indicate that the values of\ndielectric constant show a steep decrease with increasing frequency for each\nvoltage. The values of dielectric loss as a function of voltage show a jump,\nand dielectric loss decreases with decreasing voltage and increasing frequency.\nThe weak increasing of the ac electrical conductivity on frequency is observed.\nThe real part of electric modulus increases with increasing frequency. Also,\nthe imaginary part of electric modulus shows a peak and the peak position\nshifts to higher frequency with increasing applied voltage. It can be concluded\nthat the interfacial polarization can be more easily occurred at low\nfrequencies and the majority of interface states at metal semiconductor\ninterface contributes to deviation of dielectric properties of Al/MA/p-Si\nstructures."
    },
    {
        "anchor": "Surface Instability of Icicles: Quantitatively-unexplained stationary waves or ridges often encircle icicles.\nSuch waves form when roughly 0.1 mm-thick layers of water flow down the icicle.\nThese waves typically have a wavelength of 1cm approximately independent of\nexternal temperature, icicle thickness, and the volumetric rate of water flow.\nIn this paper we show that these waves can not be obtained by naive\nMullins-Sekerka instability, but are caused by a quite new surface instability\nrelated to the thermal diffusion and hydrodynamic effect of thin water flow.",
        "positive": "The Open Catalyst 2020 (OC20) Dataset and Community Challenges: Catalyst discovery and optimization is key to solving many societal and\nenergy challenges including solar fuels synthesis, long-term energy storage,\nand renewable fertilizer production. Despite considerable effort by the\ncatalysis community to apply machine learning models to the computational\ncatalyst discovery process, it remains an open challenge to build models that\ncan generalize across both elemental compositions of surfaces and adsorbate\nidentity/configurations, perhaps because datasets have been smaller in\ncatalysis than related fields. To address this we developed the OC20 dataset,\nconsisting of 1,281,040 Density Functional Theory (DFT) relaxations\n(~264,890,000 single point evaluations) across a wide swath of materials,\nsurfaces, and adsorbates (nitrogen, carbon, and oxygen chemistries). We\nsupplemented this dataset with randomly perturbed structures, short timescale\nmolecular dynamics, and electronic structure analyses. The dataset comprises\nthree central tasks indicative of day-to-day catalyst modeling and comes with\npre-defined train/validation/test splits to facilitate direct comparisons with\nfuture model development efforts. We applied three state-of-the-art graph\nneural network models (CGCNN, SchNet, Dimenet++) to each of these tasks as\nbaseline demonstrations for the community to build on. In almost every task, no\nupper limit on model size was identified, suggesting that even larger models\nare likely to improve on initial results. The dataset and baseline models are\nboth provided as open resources, as well as a public leader board to encourage\ncommunity contributions to solve these important tasks."
    },
    {
        "anchor": "Multiscale modeling of plastic deformation of molybdenum and tungsten:\n  I. Atomistic studies of the core structure and glide of 1/2<111> screw\n  dislocations at 0 K: Owing to their non-planar cores 1/2<111> screw dislocations govern the\nplastic deformation of BCC metals. Atomistic studies of the glide of these\ndislocations at 0 K have been performed using Bond Order Potentials for\nmolybdenum and tungsten that account for the mixed metallic and covalent\nbonding in transition metals. When applying pure shear stress in the slip\ndirection it displays significant twinning-antitwinning asymmetry for\nmolybdenum but not for tungsten. However, for tensile/compressive loading the\nSchmid law breaks down in both metals, principally due to the effect of shear\nstresses perpendicular to the slip direction that alter the dislocation core.\nRecognition of this phenomenon forms a basis for the development of physically\nbased yield criteria that capture the breakdown of the Schmid law in BCC\nmetals. Moreover, dislocation glide may be preferred on {110} planes other than\nthe most highly stressed one, which is reminiscent of the anomalous slip\nobserved in many BCC metals.",
        "positive": "Dynamics of magnetic moments coupled to electrons and lattice\n  oscillations: Inspired by the models of A. Rebei and G. J. Parker and A. Rebei et. al., we\nstudy a physical model which describes the behaviour of magnetic moments in a\nferromagnet. The magnetic moments are associated to 3d electrons which interact\nwith conduction band electrons and with phonons. We study each interaction\nseparately and then collect the results assuming that the electron-phonon\ninteraction can be neglected. For the case of the spin-phonon interaction, we\nstudy the derivation of the equations of motion for the classical spin vector\nand find that the correct behaviour, as given by the Brown equation for the\nspin vector and the Bloch equation, using the results obtained by D. A. Garanin\nfor the average over fluctuations of the spin vector, can be obtained in the\nhigh temperature limit. At finite temperatures we show that the Markovian\napproximation for the fluctuations is not correct for time scales below some\nthermal correlation time $\\tau_{Th}$. For the case of electrons we workout a\nperturbative expansion of the Feynman-Vernon functional. We find the expression\nfor the random field correlation function. The composite model (as well as the\nindividual models) is shown to satisfy a fluctuation-dissipation theorem for\nall temperature regimes if the behaviour of the coupling constants of the\nphonon-spin interaction remains unchanged with the temperature. The equations\nof motion are derived."
    },
    {
        "anchor": "H4O and other hydrogen-oxygen compounds at giant-planet core pressures: Water and hydrogen at high pressure make up a substantial fraction of the\ninteriors of giant planets. Using ab initio random structure search methods we\ninvestigate the ground-state crystal structures of water, hydrogen, and\nhydrogen-oxygen compounds. We find that, at pressures beyond 14 Mbar, excess\nhydrogen is incorporated into the ice phase to form a novel structure with H4O\nstoichiometry. We also predict two new ground state structures, P2_1/m and\nI4/mmm, for post-C2/m water ice.",
        "positive": "Anomalous Ferromagnetism in TbMnO3 Thin Films: Magnetometry, x-ray, and neutron scattering have been used to study the\nstructural and magnetic properties of a TbMnO3 thin film grown on a [001]\nSrTiO3 substrate by pulsed laser deposition. Although bulk TbMnO3 is a low\ntemperature antiferromagnet, magnetometry measurements indicate the presence of\nlow temperature ferromagnetism. Depth profiling by x-ray and polarized neutron\nreflectometry reveals a net sample magnetization that is commensurate with the\nfilm thickness, indicating that the observed ferromagnetism is not due to an\naltered surface phase (such as Mn3O4), or external impurities that might give\nrise to an artificial magnetic signal. Instead, these results show that the\nferromagnetism is an intrinsic property of the TbMnO3 film."
    },
    {
        "anchor": "Magnetotransport Properties and Fermi Surface Topology of Nodal line\n  Semimetal InBi: In the present study, we have discussed the up-turn behavior in the\nresistivity pattern of the topological nodal line semimetal InBi. We argued\nthat such nature could be generalized with a mathematical model, that can be\napplied to any compounds exhibiting similar behavior. The extremely high\nmagnetoresistance (XMR) has also been explained by the carrier compensation in\nthe compound, estimated from the Hall conductivity. Moreover, from the study of\nSubhnikov-de Haas (SdH) oscillation and density functional theory (DFT), we\nobtained the complete three-dimensional (3D) Fermi surface topology of the\ncompound InBi. A detailed understanding of carriers' behavior has been\ndiscussed using those studies. We have also unfurled the topology of each\nelectron and hole pocket and its possible modulation with electron and hole\ndoping.",
        "positive": "Stretching magnetism with an electric field in a nitride semiconductor: By direct magnetization measurements, performed employing a new detection\nscheme, we demonstrate an electrical control of magnetization in wurtzite\n(Ga,Mn)N. In this dilute magnetic insulator the Fermi energy is pinned by Mn\nions in the mid-gap region, and the Mn3+ ions show strong single-ion\nanisotropy. We establish that (Ga,Mn)N sustains an electric field up to at\nleast 5 MV/cm, indicating that Mn doping turns GaN into a worthwhile\nsemi-insulating material. Under these conditions, the magnetoelectric coupling\nmay be driven by the inverse piezoelectric effect that stretches the elementary\ncell along the c axis and, thus, affects the magnitude of magnetic anisotropy.\nWe develop a corresponding theory and show that it describes the experimentally\ndetermined dependence of magnetization on the electric field quantitatively\nwith no adjustable parameters as a function of the magnetic field and\ntemperature. In this way, our work bridges two research domains developed so\nfar independently: piezoelectricity of wurtzite semiconductors and electrical\ncontrol of magnetization in hybrid and composite magnetic structures containing\npiezoelectric components."
    },
    {
        "anchor": "Absence of zero-field-cooled exchange bias effect in single crystalline\n  La2-xAxCoMnO6 (A = Ca, Sr) compounds: Magnetic properties of A2BB'O6 (A = rare or alkaline earth ions; B,B' =\ntransition metal ions) double perovskites are of great interest due to their\npotential spintronic applications. Particularly fascinating is the zero field\ncooled exchange bias (ZEB) effect observed for the hole doped La2-xAxCoMnO6\npolycrystalline samples. In this work we synthesize La2CoMnO6,\nLa1.5Ca0.5CoMnO6, and La1.5Sr0.5CoMnO6 single crystals by the floating zone\nmethod and study their magnetic behavior. The three materials are\nferromagnetic. Surprisingly, we observe no zero or even conventional exchange\nbias effect for the Ca and Sr doped single crystals, in sharp contrast to\npolycrystalline samples. This absence indicates that the lack of grain\nboundaries and spin glass-like behavior, not observed in our samples, might be\nkey ingredients for the spontaneous exchange bias phenomena seen in\npolycrystalline samples.",
        "positive": "Porous silicon formation and electropolishing: Electrochemical etching of silicon in hydrofluoride containing electrolytes\nleads to pore formation for low and to electropolishing for high applied\ncurrent. The transition between pore formation and polishing is accompanied by\na change of the valence of the electrochemical dissolution reaction. The local\netching rate at the interface between the semiconductor and the electrolyte is\ndetermined by the local current density. We model the transport of reactants\nand reaction products and thus the current density in both, the semiconductor\nand the electrolyte. Basic features of the chemical reaction at the interface\nare summarized in law of mass action type boundary conditions for the transport\nequations at the interface. We investigate the linear stability of a planar and\nflat interface. Upon increasing the current density the stability flips either\nthrough a change of the valence of the dissolution reaction or by a nonlinear\nboundary conditions at the interface."
    },
    {
        "anchor": "Manipulation of type-I and type-II Dirac points in PdTe2 superconductor\n  by external pressure: A pair of type-II Dirac cones in PdTe$_2$ was recently predicted by theories\nand confirmed in experiments, making PdTe$_2$ the first material that processes\nboth superconductivity and type-II Dirac fermions. In this work, we study the\nevolution of Dirac cones in PdTe$_2$ under hydrostatic pressure by the\nfirst-principles calculations. Our results show that the pair of type-II Dirac\npoints disappears at 6.1 GPa. Interestingly, a new pair of type-I Dirac points\nfrom the same two bands emerges at 4.7 GPa. Due to the distinctive band\nstructures compared with those of PtSe$_2$ and PtTe$_2$, the two types of Dirac\npoints can coexist in PdTe$_2$ under proper pressure (4.7-6.1 GPa). The\nemergence of type-I Dirac cones and the disappearance of type-II Dirac ones are\nattributed to the increase/decrease of the energy of the states at $\\Gamma$ and\n$A$ point, which have the anti-bonding/bonding characters of interlayer Te-Te\natoms. On the other hand, we find that the superconductivity of PdTe$_2$\nslightly decreases with pressure. The pressure-induced different types of Dirac\ncones combined with superconductivity may open a promising way to investigate\nthe complex interactions between Dirac fermions and superconducting\nquasi-particles.",
        "positive": "Electrical properties of Bi-implanted amorphous chalcogenide films: The impact of Bi implantation on the conductivity and the thermopower of\nGeTe, Ge-Sb-Te, and Ga- La-S films is investigated. The enhanced conductivity\nappears to be notably sensitive to a dose of an implant. Incorporation of Bi in\namorphous chalcogenide films at doses up to 1x1015 cm-2 is seen not to change\nthe majority carrier type and activation energy for the conduction process.\nHigher implantation doses may reverse the majority carrier type in the studied\nfilms. Electron conductivity was observed in GeTe films implanted with Bi at a\ndose of 2x1016 cm-2. These studies indicate that native coordination defects\npresent in amorphous chalcogenide semiconductors can be deactivated by means of\nion implantation. A substantial density of implantation-induced traps in the\nstudied films and their interfaces with silicon is inferred from analysis of\nthe space-charge limited current and capacitance-voltage characteristics taken\non Au/amorphous chalcogenide/Si structures."
    },
    {
        "anchor": "Transformable Biomimetic Liquid Metal Chameleon: Liquid metal (LM) is of current core interest for a wide variety of newly\nemerging areas. However, the functional materials thus made so far by LM only\ncould display a single silver-white appearance. Here in this study, the new\nconceptual colorful LM marbles working like transformable biomimetic chameleons\nwere proposed and fabricated from LM droplets through encasing them with\nfluorescent nano-particles. We demonstrated that this unique LM marble can be\nmanipulated into various stable magnificent appearances as one desires. And it\ncan also splitt and merge among different colors. Such multifunctional LM\nchameleon is capable of responding to the outside electric-stimulus and\nrealizing shape transformation and discoloration behaviors as well. Further\nmore, the electric-stimuli has been disclosed to be an easy going way to\ntrigger the release of nano/micro-particles from the LM. The present\nfluorescent biomimetic liquid metal chameleon is expected to offer important\nopportunities for diverse unconventional applications, especially in a wide\nvariety of functional smart material and color changeable soft robot areas.",
        "positive": "Out-of-plane carrier spin in transition-metal dichalcogenides under\n  electric current: In a multilayer comprising ferromagnet and heavy metal, in-plane carrier spin\nis induced by applied electric current owing to Rashba spin-orbit coupling,\nwhile the out-of-plane component is absent. We propose the out-of-plane carrier\nspin can emerge in ferromagnetic transition-metal dichalcogenides monolayer, by\nsymmetry arguments and first-principles calculations. An intrinsic spin-orbit\ncoupling in the monolayer provides valley-contrasting Zeeman-type spin\nsplitting for generating the vertical induced spin. The current direction can\nbe exploited to tune the induced spin, accompanied with valley polarization.\nThe exotic spin accumulation paves an accessible way for perpendicular\nmagnetization switching and electric control of valleys."
    },
    {
        "anchor": "Electron-Beam Manipulation of Silicon Impurities in Single-Walled Carbon\n  Nanotubes: The recent discovery that impurity atoms in crystals can be manipulated with\nfocused electron irradiation has opened novel perspectives for top-down atomic\nengineering. These achievements have been enabled by advances in electron\noptics and microscope stability, but also in the preparation of suitable\nmaterials with impurity elements incorporated via ion and electron-beam\nirradiation or chemical means. Here it is shown that silicon heteroatoms\nintroduced via plasma irradiation into the lattice of single-walled carbon\nnanotubes (SWCNTs) can be manipulated using a focused 55-60 keV electron probe\naimed at neighboring carbon sites. Moving the silicon atom mainly along the\nlongitudinal axis of large 2.7 nm diameter tubes, more than 90 controlled\nlattice jumps were recorded and the relevant displacement cross sections\nestimated. Molecular dynamics simulations show that even in 2 nm SWCNTs the\nthreshold energies for out-of-plane dynamics are different than in graphene,\nand depend on the orientation of the silicon-carbon bond with respect to the\nelectron beam as well as the local bonding of the displaced carbon atom and its\nneighbors. Atomic-level engineering of SWCNTs where the electron wave functions\nare more strictly confined than in two-dimensional materials may enable the\nfabrication of tunable electronic resonators and other devices.",
        "positive": "Theory of orbital magnetic quadrupole moment and magnetoelectric\n  susceptibility: We derive a quantum-mechanical formula of the orbital magnetic quadrupole\nmoment (MQM) in periodic systems by using the gauge-covariant gradient\nexpansion. This formula is valid for insulators and metals at zero and finite\ntemperature. We also prove a direct relation between the MQM and\nmagnetoelectric (ME) susceptibility for insulators at zero temperature. It\nindicates that the MQM is a microscopic origin of the ME effect. Using the\nformula, we quantitatively estimate these quantities for room-temperature\nantiferromagnetic semiconductors BaMn$_2$As$_2$ and CeMn$_2$Ge$_{2 - x}$Si$_x$.\nWe find that the orbital contribution to the ME susceptibility is comparable\nwith or even dominant over the spin contribution."
    },
    {
        "anchor": "Quantum Electrodynamics is Crucial for Plasmonic Resonance of Metallic\n  Nanostructures: Plasmonic resonance of a metallic nanostructure results from coherent motion\nof its conduction electrons driven by incident light. At the resonance, the\ninduced dipole in the nanostructure is proportional to the number of the\nconduction electrons, hence $10^{7}$ times larger than that in an atom. The\ninteraction energy between the induced dipole and fluctuating virtual field of\nthe incident light can reach a few tenths of an eV. Therefore, the classical\nelectromagnetism dominating the field becomes inadequate. We argue that quantum\nelectrodynamics (QED) should be used instead as the fundamental theory to\ndescribe the virtual field and its interaction with the electrons. Based on\nQED, we derive analytic expressions for the plasmonic resonant frequency, which\ndepends on three easily accessible material parameters. The analytic theory\nreproduces very well the experimental data, and can be used for rational design\nof materials.",
        "positive": "Pseudopotentials for high-throughput DFT calculations: The increasing use of high-throughput density-functional theory (DFT)\ncalculations in the computational design and optimization of materials requires\nthe availability of a comprehensive set of soft and transferable\npseudopotentials. Here we present design criteria and testing results for a new\nopen-source \"GBRV\" ultrasoft pseudopotential library that has been optimized\nfor use in high-throughput DFT calculations. We benchmark the GBRV potentials,\nas well as two other pseudopotential sets available in the literature, to\nall-electron calculations in order to validate their accuracy. The results\nallow us to draw conclusions about the accuracy of modern pseudopotentials in a\nvariety of chemical environments."
    },
    {
        "anchor": "Room Temperature Structural, Magnetic and Dielectric Characteristics of\n  La Doped CuO Bulk Multiferroic: In this manuscript, we report room temperature structural, microstructural,\noptical, dielectric, and magnetic properties of CuO and Cu0.995La0.005\nceramics, synthesized by solid-state reaction method. La doping in CuO leads to\nthe evolution of compact and dense microstructure with reduced porosity. Due to\nnoticeable differences in the ionic radii of, La doping creates vacancy defects\nwhich induce considerable strain in the CuO lattice resulting in a reduction in\nthe lattice parameters and cell volume. However, both ceramics processes a\nsimilar monoclinic structure with the C2/c space group. Detailed\ncharacterization using XPS, Raman, and FTIR spectroscopy confirmed the\nincorporation of the La3+ in CuO lattice. Interestingly, La doping enhances the\ndielectric constant by more than three times and results in a reduced leakage\ncurrent. The onset of a large dielectric constant is attributed to dense\nmicrostructure and strain/distortion in CuO lattice after La doping.\nAdditionally, the band-gap of Cu0.995La0.005 ceramics decreases which is\nattributed to increased vacancy defect concentration that creates intermediate\ndopant energy level within bandgap of CuO matrix. Furthermore, improvement in\nmagnetic and dielectric properties is also discussed and correlated with the\ngrain size in La-doped CuO.",
        "positive": "Giant exciton Mott density in anatase TiO2: Elucidating the carrier density at which strongly bound excitons dissociate\ninto a plasma of uncorrelated electron-hole pairs is a central topic in the\nmany-body physics of semiconductors. However, there is a lack of information on\nthe high-density response of excitons absorbing in the near-to-mid ultraviolet,\ndue to the absence of suitable experimental probes in this elusive spectral\nrange. Here, we present a unique combination of many-body perturbation theory\nand state-of-the-art ultrafast broadband ultraviolet spectroscopy to unveil the\ninterplay between the ultraviolet-absorbing two-dimensional excitons of anatase\nTiO$_2$ and a sea of electron-hole pairs. We discover that the critical density\nfor the exciton Mott transition in this material is the highest ever reported\nin semiconductors. These results deepen our knowledge of the exciton Mott\ntransition and pave the route toward the investigation of the exciton phase\ndiagram in a variety of wide-gap insulators."
    },
    {
        "anchor": "Synergism between B and Nb improves fire resistance in microalloyed\n  steels: The development of new fire-resistant steels represents a challenge in\nmaterials science and engineering of utmost importance. Alloying elements such\nas Nb and Mo are generally used to improve the strength at both room- and\nhigh-temperatures due to, for example, the formation of precipitates and harder\nmicroconstituents. In this study we show alternatively that the addition of\nsmall amounts of boron in Nb-microalloyed steels may play a crucial role in\nmaintaining the mechanical properties at high temperatures. The 66\\,\\%\nyield-strength criteria for fire resistance is achieved at $\\approx\n574$\\,{\\deg}C for a boron steel, whereas without boron this value reaches\n$\\approx 460$\\,{\\deg}C, a remarkable boron-induced mechanical strengthening\nenhancement. DFT calculations show that boron additions can lower the vacancy\nformation energy when compared to pure ferrite and, for Nb-B steels, there is a\nfurther 24\\,\\% reduction, suggesting that the boron-niobium combination acts as\nan effective pinning-based strengthening agent.",
        "positive": "Ab initio investigation on oxygen defect clusters in UO2+x: By first-principles LSDA+U calculations, we revealed that the current\nphysical picture of defective uranium dioxide suggested solely by neutron\ndiffraction analysis is unsatisfactory. An understanding based on quantum\ntheory has been established as a thermodynamical competition among point\ndefects and cuboctahedral cluster, which naturally interprets the puzzled\norigin of the asymmetric O' and O'' interstitials. It also gives a clear and\nconsistent agreement with most available experimental data. Unfortunately, the\nobserved high occupation of O'' site cannot be accounted for in this picture\nand is still a challenge for theoretical simulations."
    },
    {
        "anchor": "Three-dimensional Printing of Mycelium Hydrogels into Living Complex\n  Materials: Biological living materials, such as animal bones and plant stems, are able\nto self-heal, regenerate, adapt and make decisions under environmental\npressures. Despite recent successful efforts to imbue synthetic materials with\nsome of these remarkable functionalities, many emerging properties of complex\nadaptive systems found in biology remain unexplored in engineered living\nmaterials. Here, we report on a three-dimensional printing approach that\nharnesses the emerging properties of fungal mycelium to create living complex\nmaterials that self-repair, regenerate and adapt to the environment while\nfulfilling an engineering function. Hydrogels loaded with the fungus Ganoderma\nlucidum are 3D printed into lattice architectures to enable mycelial growth in\na balanced exploration and exploitation pattern that simultaneously promotes\ncolonization of the gel and bridging of air gaps. To illustrate the potential\nof such living complex materials, we 3D print a robotic skin that is\nmechanically robust, self-cleaning, and able to autonomously regenerate after\ndamage.",
        "positive": "New type of incommensurate magnetic ordering in Mn3TeO6: The complex metal oxide Mn3TeO6 exhibits a corundum related structure and has\nbeen prepared both in forms of single crystals by chemical transport reactions\nand of polycrystalline powders by a solid state reaction route. The crystal\nstructure and magnetic properties have been investigated using a combination of\nX-ray and neutron powder diffraction, electron microscopy, calorimetric and\nmagnetic measurements. At room temperature this compound adopts a trigonal\nstructure, space group R3 with a = 8.8679(1) {\\AA}, c = 10.6727(2) {\\AA}. A\nlong-range magnetically ordered state is identified below 23 K. An unexpected\nfeature of this magnetic structure is several types of Mn-chains. Under the\naction of the incommensurate magnetic propagation vector k = [0, 0, 0.4302(1)]\nthe unique Mn site is split into two magnetically different orbits. One orbit\nforms a perfect helix with the spiral axis along the c-axis while the other\norbit has a sine wave character along the c-axis."
    },
    {
        "anchor": "Pushing the detection limit of Magnetic Circular Dichroism to 2 nm: Magnetic Circular Dichroism (MCD) is a standard technique for the study of\nmagnetic properties of materials in synchrotron beamlines. We present here a\nnew scattering geometry in the Transmission Electron Microscope through which\nMCD can be observed with unprecedented spatial resolution. A convergent\nelectron beam is used to scan a multilayer Fe/Au sample and record energy loss\nspectra. Differences in the spectra induced by the magnetic moments of the Fe\natoms can be resolved with a resolution of 2 nm. This is a breakthrough\nachievement when compared both to the previous EMCD resolution (200 nm) or the\nbest XMCD experiments (approx. 20 nm), with an improvement of two and one order\nof magnitude, respectively.",
        "positive": "Ferromagnetic van der Waals crystal VI3: We report structural, physical properties and electronic structure of van der\nWaals (vdW) crystal VI3. Detailed analysis reveals that VI3 exhibits a\nstructural transition from monoclinic C2/m to rhombohedral R-3 at Ts ~ 79 K,\nsimilar to CrX3 (X = Cl, Br, I). Below Ts, a long-range ferromagnetic (FM)\ntransition emerges at Tc ~ 50 K. The local moment of V in VI3 is close to the\nhigh-spin state V3+ ion (S = 1). Theoretical calculation suggests that VI3 may\nbe a Mott insulator with the band gap of about 0.84 eV. In addition, VI3 has a\nrelative small interlayer binding energy and can be exfoliated easily down to\nfew layers experimentally. Therefore, VI3 is a candidate of two-dimensional FM\nsemiconductor. It also provides a novel platform to explore 2D magnetism and\nvdW heterostructures in S = 1 system."
    },
    {
        "anchor": "Structural defects in MBE-grown CdTe-based heterojunctions for\n  photovoltaic applications: Structural defects in the p-ZnTe/i-CdTe/n-CdTe single-crystalline\nheterojunctions designed for photovoltaic applications have been investigated\nby transmission electron microscopy (TEM) and deep-level transient spectroscopy\n(DLTS). Lattice parameters and misfit strain in the undoped CdTe absorber\nlayers of the heterojunctions, grown by the molecular-beam epitaxy technique on\ntwo different substrates, GaAs and CdTe, have been determined with\nhigh-resolution X-ray diffractometry. A dense network of misfit dislocations at\nthe lattice-mismatched CdTe/GaAs and ZnTe/CdTe interfaces and numerous\nthreading dislocations and stacking faults have been shown by the\ncross-sectional TEM imaging of the heterojunctions. The DLTS measurements\nrevealed five deep-level traps in the heterojunctions grown on the GaAs\nsubstrates and only three of them in the heterojunctions grown on CdTe. One of\nthe traps, showing the exponential capture kinetics of charge carriers, has\nbeen identified as associated with the double acceptor level of Cd vacancies in\nthe CdTe absorber layers. All the other traps have been attributed to the\nelectronic states of extended defects, presumably dislocations, on the grounds\nof their logarithmic capture kinetics. Two of these traps, displaying the\nlargest values of their capture cross-section and the properties characteristic\nof bandlike electronic states, have been ascribed to the core states of\ndislocations. It is argued that they are most likely responsible for decreased\nlifetime of photo-excited carriers resulting in a low energy conversion\nefficiency of solar cells based on similarly grown heterojunctions.",
        "positive": "Dopant-vacancy binding effects in Li-doped magnesium hydride: We use a combination of ab initio calculations and statistical mechanics to\ninvestigate the substitution of Li+ for Mg2+ in magnesium hydride (MgH2)\naccompanied by the formation of hydrogen vacancies with positive charge (with\nrespect to the original ion at the site). We show here that the binding energy\nbetween dopants and vacancy defects leads to a significant fraction of trapped\nvacancies and therefore a dramatic reduction of the number of free vacancies\navailable for diffusion. The concentration of free vacancies initially\nincreases with dopant concentration, but reaches a maximum at around 1 mol% Li\ndoping and slowly decreases with further doping. At the optimal level of\ndoping, the corresponding concentration of free vacancies is much higher than\nthe equilibrium concentrations of charged and neutral vacancies in pure MgH2 at\ntypical hydrogen storage conditions. We also show that Li-doped MgH2 is\nthermodynamically metastable with respect to phase separation into pure\nmagnesium and lithium hydrides at any significant Li concentration, even after\nconsidering the stabilization provided by dopant-vacancy interactions and\nconfigurational entropic effects. Our results suggest that lithium doping may\nenhance hydrogen diffusion hydride, but only to a limited extent determined by\nan optimal dopant concentration and conditioned to the stability of the doped\nphase."
    },
    {
        "anchor": "Level repulsion and evanescent waves in sonic crystals: This work theoretically and experimentally reports the evanescent connections\nbetween propagating bands in periodic acoustic materials. The complex band\nstructures obtained by solving for the $k(\\omega)$ problem reveal a complete\ninterpretation of the propagation properties of these systems. The prediction\nof evanescent modes, non predicted by classical $\\omega(\\vec{k})$ methods, is\nof interest for the understanding of these propagation properties. Complex band\nstructures provide an interpretation of the evanescent coupling and the level\nrepulsion states showing the possibility to control of evanescent waves in\nperiodic materials.",
        "positive": "Mode- and Space- Resolved Thermal Transport of Alloy Nanostructures: Nanostructured semiconducting alloys obtain ultra-low thermal conductivity as\na result of the scattering of phonons with a wide range of mean-free-paths\n(MFPs). In these materials, long-MFP phonons are scattered at the nanoscale\nboundaries whereas short-MFP high-frequency phonons are impeded by disordered\npoint defects introduced by alloying. While this trend has been validated by\nsimplified analytical and numerical methods, an ab-initio space-resolved\napproach remains elusive. To fill this gap, we calculate the thermal\nconductivity reduction in porous alloys by solving the mode-resolved Boltzmann\ntransport equation for phonons using the finite-volume approach. We analyze\ndifferent alloys, length-scales, concentrations, and temperatures, obtaining a\nvery large reduction in the thermal conductivity over the entire configuration\nspace. For example, a ~97% reduction is found for Al$_{0.8}$In$_{0.2}$As with\n25% porosity. Furthermore, we employ these simulations to validate our recently\nintroduced \"Ballistic Correction Model\" (BCM), an approach that estimates the\neffective thermal conductivity using the characteristic MFP of the bulk alloy\nand the length-scale of the material. The BCM is then used to provide guiding\nprinciples in designing alloy-based nanostructures. Notably, it elucidates how\nporous alloys such as Si$_{x}$Ge$_{1-x}$ obtain larger thermal conductivity\nreduction compared to porous Si or Ge, while also explaining why we should not\nexpect similar behavior in alloys such as Al$_{x}$In$_{1-x}$As. By taking into\naccount the synergy from scattering at different scales, we provide a route for\nthe design of materials with ultra-low thermal conductivity."
    },
    {
        "anchor": "White Lines and 3d-Occupancy for the 3d Transition-Metal Oxides: Electron energy-loss spectrometry was employed to measure the white lines at\nthe L23 absorption edges of the 3d transition-metal oxides and lithium\ntransition-metal oxides. The white-line ratio (L3/L2) was found to increase\nbetween d^0 and d^5 and decrease between d^5 and d^10, consistent with previous\nresults for the transition metals and their oxides. The intensities of the\nwhite lines, normalized to the post-edge background, are linear for the 3d\ntransition-metal oxides and lithium transition-metal oxides. An empirical\ncorrelation between normalized white-line intensity and 3d occupancy is\nestablished. It provides a method for measuring changes in the 3d-state\noccupancy. As an example, this empirical relationship is used to measure\nchanges in the transition-metal valences of Li_{1-x}Ni_{0.8}Co_{0.2}O_2 in the\nrange of 0 < x < 0.64. In these experiments the 3d occupancy of the nickel ion\ndecreased upon lithium deintercalation, while the cobalt valence remained\nconstant.",
        "positive": "Optical property modification of ZnO: Effect of 1.2 MeV Ar irradiation: We report a systematic study on 1.2 MeV Ar^8+ irradiated ZnO by x-ray\ndiffraction (XRD), room temperature photoluminescence (PL) and\nultraviolet-visible (UV-Vis) absorption measurements. ZnO retains its wurtzite\ncrystal structure up to maximum fluence of 5 x 10^16 ions/cm^2. Even, the width\nof the XRD peaks changes little with irradiation. The UV-Vis absorption spectra\nof the samples, unirradiated and irradiated with lowest fluence (1 x 10^15\nions/cm^2), are nearly same. However, the PL emission is largely quenched for\nthis irradiated sample. Red shift of the absorption edge has been noticed for\nhigher fluence. It has been found that red shift is due to at least two defect\ncenters. The PL emission is recovered for 5 x 10^15 ions/cm^2 fluence. The\nsample colour is changed to orange and then to dark brown with increasing\nirradiation fluence. Huge resistivity decrease is observed for the sample\nirradiated with 5 x 10^15 ions/cm^2 fluence. Results altogether indicate the\nevolution of stable oxygen vacancies and zinc interstitials as dominant defects\nfor high fluence irradiation."
    },
    {
        "anchor": "Transition-Metal Nitride Halide Dielectrics for Transition-Metal\n  Dichalcogenide Transistors: Using first-principles calculations, we investigate six transition-metal\nnitride halides (TMNHs): HfNBr, HfNCl, TiNBr, TiNCl, ZrNBr, and ZrNCl as\npotential van der Waals (vdW) dielectrics for transition metal dichalcogenide\n(TMD) channel transistors. We calculate the exfoliation energies and bulk\nphonon energies and find that the six TMNHs are exfoliable and\nthermodynamically stable. We calculate both the optical and static dielectric\nconstants in the in-plane and out-of-plane directions for both monolayer and\nbulk TMNHs. In monolayers, the out-of-plane static dielectric constant ranges\nfrom 5.04 (ZrNCl) to 6.03 (ZrNBr) whereas in-plane dielectric constants range\nfrom 13.18 (HfNBr) to 74.52 (TiNCl). We show that the bandgap of TMNHs ranges\nfrom 1.53 eV (TiNBr) to 3.36 eV (HfNCl) whereas the affinity ranges from 4.01\neV (HfNBr) to 5.60 eV (TiNCl). Finally, we estimate the dielectric leakage\ncurrent density of transistors with six TMNH monolayer dielectrics with five\nmonolayer channel TMDs (MoS2, MoSe2, MoTe2, WS2, and WSe2). For p-MOS TMD\nchannel transistors, 19 out of 30 combinations have a smaller leakage current\ncompared to monolayer hexagonal boron nitride (hBN), a well-known vdW\ndielectric. The smallest monolayer leakage current of 2.14*10-9 A/cm2 is\npredicted for a p-MOS WS2 transistor with HfNCl as a gate dielectric. HfNBr,\nHfNCl, ZrNBr, and ZrNCl are also predicted to yield small leakage currents in\ncertain p-MOS TMD transistors.",
        "positive": "A New Line Defect in NdTiO3 Perovskite: Perovskite oxides form an eclectic class of materials owing to their\nstructural flexibility in accommodating cations of different sizes and\nvalences. They host well known point and planar defects, but so far no line\ndefect has been identified other than dislocations. Using analytical scanning\ntransmission electron microscopy (STEM) and ab initio calculations we have\ndetected and characterized the atomic and electronic structures of a novel line\ndefect in NdTiO3 perovskite. It appears in STEM images as a perovskite cell\nrotated by 45 degrees. It consists of self-organized Ti-O vacancy lines\nreplaced by Nd columns surrounding a central Ti-O octahedral chain containing\nTi4+ ions, as opposed to Ti3+ in the host. The distinct Ti valence in this line\ndefect introduces the possibility of engineering exotic conducting properties\nin a single preferred direction and tailoring novel desirable functionalities\nin this Mott insulator."
    },
    {
        "anchor": "NMR comparative study of PbMg_1/3Nb_2/3O_3 and PbSc_1/2Nb_1/2O_3 local\n  structure: The 93Nb and 45Sc NMR spectra in PbSc_1/2Nb_1/2O_3 (PSN) and\nPbMg_1/3Nb_2/3O_3 (PMN) disordered relaxor ferroelectrics at the temperature T\n> T_0 (T_0 is the temperature of the dielectric susceptibility maximum) have\nbeen studied. Spectra analysis was performed on the base both of the analytical\ndescription of NMR lines shapes, allowing for homogeneous and inhomogeneous\nbroadening related to a random distribution of the electric field gradients and\nnumerical Monte Carlo method taking into account electric field gradients\noriginated from random distribution of Mg, Sc and Nb ions (which may be shifted\nor not) over B-type cation sites. The observed 1/2 -1/2 transition spectrum\nboth of the 93Nb and 45Sc nuclei in the PSN was shown to contain a narrow (3-4\nkHz) almost isotropic part and a broad strongly anisotropic part. These two\ncomponents of NMR spectra are related to 1:1 Sc/Nb ordered and compositionally\ndisordered regions of the crystal, respectively. It was shown that in the\ndisordered regions Sc^3+, Nb^5+ and O^2- ions are shifted from their cubic\nlattice sites at one of three possible directions: <100>, <110> or <111>. In\nPMN the NMR spectrum of 93Nb contains practically only the broad component. The\nportion of unbroadened spectrum that may correspond to ideal 1:2 regions\naccounts only for 1-2 percent of the total integral intensity. No evidance was\nobtained about existence of the 1:1 regions in PMN. The NMR data demonstrate\nthat in PMN the cubic symmetry at T > T_0 is locally broken due to ions shifts\nsimilar to that in disordered PSN. The values of the ion shifts were estimated\nin the point charges point dipoles approximation of the electric field\ngradients calculation both in the PSN and PMN.",
        "positive": "Delta-doped \\b{eta}-Ga2O3 thin films and\n  \\b{eta}-(Al0.26Ga0.74)2O3/\\b{eta}-Ga2O3 heterostructures grown by\n  metalorganic vapor-phase epitaxy: We report on silicon delta doping of metalorganic vapor-phase epitaxy-grown\n\\b{eta}-Ga2O3 thin films using silane precursor. Delta-doped \\b{eta}-Ga2O3\nepitaxial films are characterized using capacitance-voltage profiling and\nsecondary-ion mass spectroscopy. Electron sheet charge density in the range of\n2.9e12 cm-2 to 8e12 cm-2 with a half width at half maximum ranging from 6.2 nm\nto 3.5 nm is measured. We also demonstrate a high density (6.4e12 cm-2)\ndegenerate two-dimensional electron gas using a delta-doped\n\\b{eta}-(Al0.26Ga0.74)2O3/\\b{eta}-Ga2O3 heterostructure.The total charge could\nalso include a contribution from a parallel channel in the\n\\b{eta}-(Al0.26Ga0.74)2O3 alloy barrier."
    },
    {
        "anchor": "Electronic excitations of the charged nitrogen-vacancy center in diamond\n  obtained using time-independent variational density functional calculations: Elucidation of the mechanism for optical spin initialization of point defects\nin solids in the context of quantum applications requires an accurate\ndescription of the excited electronic states involved. While variational\ndensity functional calculations have been successful in describing the ground\nstate of a great variety of systems, doubts have been expressed in the\nliterature regarding the ability of such calculations to describe electronic\nexcitations of point defects. A direct orbital optimization method is used here\nto perform time-independent, variational density functional calculations of a\nprototypical defect, the negatively charged nitrogen-vacancy center in diamond.\nThe calculations include up to 511 atoms subject to periodic boundary\nconditions and the excited state calculations require similar computational\neffort as ground state calculations. Contrary to some previous reports, the use\nof local and semilocal density functionals gives the correct ordering of the\nlow-lying triplet and singlet states, namely ${}^{3}A_2 < {}^{1}E < {}^{1}A_1 <\n{}^{3}E$. Furthermore, the more advanced meta generalized gradient\napproximation functionals give results that are in remarkably good agreement\nwith high-level, many-body calculations as well as available experimental\nestimates, even for the excited singlet state which is often referred to as\nhaving multireference character. The lowering of the energy in the triplet\nexcited state as the atom coordinates are optimized in accordance with\nanalytical forces is also close to the experimental estimate and the resulting\nzero-phonon line triplet excitation energy is underestimated by only 0.15 eV.\nThe approach used here is found to be a promising tool for studying electronic\nexcitations of point defects in, for example, systems relevant for quantum\ntechnologies.",
        "positive": "High Performance WSe2 Field-Effect Transistors via Controlled Formation\n  of In-Plane Heterojunctions: Monolayer WSe2 is a two dimensional (2D) semiconductor with a direct bandgap,\nand it has been recently explored as a promising material for electronics and\noptoelectronics. Low field effect mobility is the main constraint preventing\nWSe2 from becoming one of the competing channel materials for field-effect\ntransistors (FETs). Recent results have demonstrated that chemical treatments\ncan modify the electrical properties of transition metal dichalcogenides\n(TMDCs) including MoS2 and WSe2. Here, we report that controlled heating in air\nsignificantly improves device performance of WSe2 FETs in terms of on-state\ncurrents and field-effect mobilities. Specifically, after heating at optimized\nconditions, chemical vapor deposition grown monolayer WSe2 FETs showed an\naverage FET mobility of 31 cm2/Vs and on/off current ratios up to 5*108. For\nfew-layer WSe2 FETs, after the same treatment applied, we achieved a high\nmobility up to 92 cm2/Vs. These values are significantly higher than FETs\nfabricated using as-grown WSe2 flakes without heating treatment, demonstrating\nthe effectiveness of air heating on the performance improvements of WSe2 FETs.\nThe underlying chemical processes involved during air heating and the formation\nof in-plane heterojunctions of WSe2 and WO3-x, which is believed to be the\nreason for the improved FET performance, were studied by spectroscopy and\ntransmission electron microscopy. We further demonstrated that by combining air\nheating method developed in this work with supporting 2D materials on BN\nsubstrate, we achieved a noteworthy field effect mobility of 83 cm2/Vs for\nmonolayer WSe2 FETs. This work is a step towards controlled modification of the\nproperties of WSe2 and potentially other TMDCs, and may greatly improve device\nperformance for future applications of 2D materials in electronics and\noptoelectronics."
    },
    {
        "anchor": "QM/MM description of periodic systems: A QM/MM implementation for periodic systems is reported. This is done for the\ncase of molecules and for systems with two and three-dimensional periodicity,\nwhich is suitable to model electrolytes in contact with electrodes. Tests on\ndifferent water-containing systems, ranging from the water dimer up to liquid\nwater indicate the correctness of the scheme. Furthermore, molecular dynamics\nsimulations are performed, as a possible direction to study realistic systems.",
        "positive": "Density Functional Theory and Deep-learning to Accelerate Data Analytics\n  in Scanning Tunneling Microscopy: We introduce the first systematic database of scanning tunneling microscope\n(STM) images obtained using density functional theory (DFT) for two-dimensional\n(2D) materials, calculated using the Tersoff-Hamann method. It currently\ncontains data for 716 exfoliable 2D materials. Examples of the five possible\nBravais lattice types for 2D materials and their Fourier-transforms are\ndiscussed. All the computational STM images generated in this work will be made\navailable on the JARVIS-DFT website\n(https://www.ctcms.nist.gov/~knc6/JVASP.html). We find excellent qualitative\nagreement between the computational and experimental STM images for selected\nmaterials. As a first example application of this database, we train a\nconvolution neural network (CNN) model to identify Bravais lattices from the\nSTM images. We believe the model can aid high-throughput experimental data\nanalysis. These computational STM images can directly aid the identification of\nphases, analyzing defects and lattice-distortions in experimental STM images,\nas well as be incorporated in the autonomous experiment workflows."
    },
    {
        "anchor": "Effect of rigid body motion in phase-field models of solid-state\n  sintering: In the last two decades, many phase-field models for solid-state sintering\nhave been published. Two groups of models have emerged, with and without the\ncontribution of rigid body motion. This paper first describes the previously\npublished phase-field model with an advection term driven by rigid body motion.\nThe model is then used to investigate the differences between models with and\nwithout rigid body motion in new benchmark geometries exhibiting markedly\ndifferent behavior. Sensitivity studies concerning the parameters of the\nrigid-body motion model are conducted and their effects on equilibrium and\nkinetic properties explored. In particular, it is shown by simulations that a\nshrinkage rate independent of system size requires the inclusion of an\nadvection term. Finally, the reason behind this behavior is explored and\nimplications for diffusion-only models are drawn.",
        "positive": "300 K Ferromagnetic Magnetic Circular Dichroism in Co2+-doped ZnO\n  Activated by Shallow Donors: Cobalt-doped ZnO (Co2+:ZnO) films were studied by magnetic circular dichroism\n(MCD) spectroscopy. A broad 300 K ferromagnetic MCD signal was observed between\n1.4 and 4.0 eV after introducing shallow donor states by exposure of\nparamagnetic Co2+:ZnO films to zinc vapor. The new sub-bandgap ferromagnetic\nMCD intensity is attributed to low-energy photoionization transitions\noriginating from a spin-split donor impurity band in ferromagnetic Co2+:ZnO."
    },
    {
        "anchor": "Polymorphic PtBi2: Growth, structure and superconducting properties: PtBi$_2$ is a polymorphic system with interesting electronic properties. Here\nwe report optimized crystal growth and structural characterization of\npyrite-type and trigonal modification of PtBi$_2$. Selected area electron\ndiffraction, X-ray powder diffraction and further Rietveld refinement confirms\nthat trigonal PtBi$_2$ crystallizes in non-centrosymmetric $P31m$ space group,\npyrite-type PtBi$_2$ in $Pa\\bar{3}$ space group. Series of\nPt$_{1-x}$Rh$_x$Bi$_2$ samples was obtained for $x=0, 0.03, 0.35$ in the\ntrigonal PtBi$_2$ structure. These Pt$_{1-x}$Rh$_x$Bi$_2$ compounds become\nsuperconducting where critical temperature increases from $T_c=600$ mK for\n$x=0$ up to $T_c=2.7$ K for $x=0.35$. Furthermore we calculate the electronic\nband structure, using the structure parameters obtained. The calculated density\nof states (DOS) shows a minimum for the stochiometric compound at the Fermi\nlevel. These findings warrant further research by broader array of experimental\ntechniques, as well as the effect of the substitution on the non-trivial band\nstructure.",
        "positive": "Charge density waves and Fermi level pinning in monolayer and bilayer\n  SnSe$_2$: Materials with reduced dimensionality often exhibit exceptional properties\nthat are different from their bulk counterparts. Here we report the emergence\nof a commensurate 2 $\\times$ 2 charge density wave (CDW) in monolayer and\nbilayer SnSe$_2$ films by scanning tunneling microscope. The visualized spatial\nmodulation of CDW phase becomes prominent near the Fermi level, which is pinned\ninside the semiconductor band gap of SnSe$_2$. We show that both CDW and Fermi\nlevel pinning are intimately correlated with band bending and virtual induced\ngap states at the semiconductor heterointerface. Through interface engineering,\nthe electron-density-dependent phase diagram is established in SnSe$_2$. Fermi\nsurface nesting between symmetry inequivalent electron pockets is revealed to\ndrive the CDW formation and to provide an alternative CDW mechanism that might\nwork in other compounds."
    },
    {
        "anchor": "A Hybrid model for the origin of photoluminescence from Ge nanocrystals\n  in SiO$_2$ matrix: In spite of several articles, the origin of visible luminescence from\ngermanium nanocrystals in SiO$_2$ matrix is controversial even today. Some\nauthors attribute the luminescence to quantum confinement of charge carriers in\nthese nanocrystals. On the other hand, surface or defect states formed during\nthe growth process, have also been proposed as the source of luminescence in\nthis system. We have addressed this long standing query by simultaneous\nphotoluminescence and Raman measurements on germanium nanocrystals embedded in\nSiO$_2$ matrix, grown by two different techniques: (i) low energy\nion-implantation and (ii) atom beam sputtering. Along with our own experimental\nobservations, we have summarized relevant information available in the\nliterature and proposed a \\emph{Hybrid Model} to explain the visible\nphotoluminescence from nanocrystalline germanium in SiO$_2$ matrix.",
        "positive": "Elucidating proximity magnetism through polarized neutron reflectometry\n  and machine learning: Polarized neutron reflectometry is a powerful technique to interrogate the\nstructures of multilayered magnetic materials with depth sensitivity and\nnanometer resolution. However, reflectometry profiles often inhabit a\ncomplicated objective function landscape using traditional fitting methods,\nposing a significant challenge to parameter retrieval. In this work, we develop\na data-driven framework to recover the sample parameters from polarized neutron\nreflectometry data with minimal user intervention. We train a variational\nautoencoder to map reflectometry profiles with moderate experimental noise to\nan interpretable, low-dimensional space from which sample parameters can be\nextracted with high resolution. We apply our method to recover the scattering\nlength density profiles of the topological insulator-ferromagnetic insulator\nheterostructure Bi$_2$Se$_3$/EuS exhibiting proximity magnetism, in good\nagreement with the results of conventional fitting. We further analyze a more\nchallenging reflectometry profile of the topological insulator-antiferromagnet\nheterostructure (Bi,Sb)$_2$Te$_3$/Cr$_2$O$_3$ and identify possible interfacial\nproximity magnetism in this material. We anticipate the framework developed\nhere can be applied to resolve hidden interfacial phenomena in a broad range of\nlayered systems."
    },
    {
        "anchor": "Exploring Phononic Properties of Two-Dimensional Materials using Machine\n  Learning Interatomic Potentials: Phononic properties are commonly studied by calculating force constants using\nthe density functional theory (DFT) simulations. Although DFT simulations offer\naccurate estimations of phonon dispersion relations or thermal properties, but\nfor low-symmetry and nanoporous structures the computational cost quickly\nbecomes very demanding. Moreover, the computational setups may yield\nnonphysical imaginary frequencies in the phonon dispersion curves, impeding the\nassessment of phononic properties and the dynamical stability of the considered\nsystem. Here, we compute phonon dispersion relations and examine the dynamical\nstability of a large ensemble of novel materials and compositions. We propose a\nfast and convenient alternative to DFT simulations which derived from\nmachine-learning interatomic potentials passively trained over computationally\nefficient ab-initio molecular dynamics trajectories. Our results for diverse\ntwo-dimensional (2D) nanomaterials confirm that the proposed computational\nstrategy can reproduce fundamental thermal properties in close agreement with\nthose obtained via the DFT approach. The presented method offers a stable,\nefficient, and convenient solution for the examination of dynamical stability\nand exploring the phononic properties of low-symmetry and porous 2D materials.",
        "positive": "Formation and Thermal Stability of sub-10 nm Carbon Templates on Si(100): We report a lithographic process for creating high-resolution (<10 nm) carbon\ntemplates on Si(100). A scanning electron microscope, operating under low\nvacuum (10E-6 mbar), produces a carbon-containing deposit (\"contamination\nresist\") on the silicon surface via electron-stimulated dissociation of ambient\nhydrocarbons, water and other adsorbed molecules. Subsequent annealing at\ntemperatures up to 1320 K in ultra-high vacuum removes SiO2 and other\ncontaminants, with no observable change in dot shape. The annealed structures\nare compatible with subsequent growth of semiconductors and complex oxides.\nCarbon dots with diameter as low as 3.5 nm are obtained with a 200 us\nelectron-beam exposure time."
    },
    {
        "anchor": "Tunable Band Gaps of In$_x$Ga$_{1-x}$N Alloys: From Bulk to\n  Two-Dimensional Limit: Using first-principles calculations combined with a semi-empirical van der\nWaals dispersion correction, we have investigated structural parameters, mixing\nenthalpies, and band gaps of buckled and planar few-layer In$_x$Ga$_{1-x}$N\nalloys. We predict that the free-standing buckled phases are less stable than\nthe planar ones. However, with hydrogen passivation, the buckled\nIn$_x$Ga$_{1-x}$N alloys become more favorable. Their band gaps can be tuned\nfrom 6 eV to 1 eV with preservation of direct band gap and well-defined Bloch\ncharacter, making them promising candidate materials for future light-emitting\napplications. Unlike their bulk counterparts, the phase separation could be\nsuppressed in these two-dimensional systems due to reduced geometrical\nconstraints. In contrast, the disordered planar thin films undergo severe\nlattice distortion, nearly losing the Bloch character for valence bands;\nwhereas the ordered planar ones maintain the Bloch character yet with the\nhighest mixing enthalpies.",
        "positive": "Charge ordering in Nd1=2Sr1=2MnO3 Nanoparticles: Nanoparticles of Nd1=2Sr1=2MnO3 of average particle sizes 12 nm and 25 nm are\nprepared by sol-gel technique. Transport, magnetotransport, magnetization and\nI-V characteristics studies have been performed on the nanoparticles. Although\nthe particle size is order of magnitude smaller than the correlation length of\ncharge ordering of the bulk material,the existence of charge ordered state has\nbeen observed in the nanoparticles at low temperature."
    },
    {
        "anchor": "An efficient method for calculating spatially extended electronic states\n  of large systems with a divide-and-conquer approach: We present an efficient post-processing method for calculating the electronic\nstructure of nanosystems based on the divide-and-conquer approach to density\nfunctional theory (DC-DFT), in which a system is divided into subsystems whose\nelectronic structure is solved separately. In this post process, the Kohn-Sham\nHamiltonian of the total system is easily derived from the orbitals and orbital\nenergies of subsystems obtained by DC-DFT without time-consuming and redundant\ncomputation. The resultant orbitals spatially extended over the total system\nare described as linear combinations of the orbitals of the subsystems. The\nsize of the Hamiltonian matrix can be much reduced from that for conventional\ncalculation, so that our method is fast and applicable to general huge systems\nfor investigating the nature of electronic states.",
        "positive": "Effect of surface chemistry on incorporation of nanoparticles within\n  calcite single crystals: Inclusion of additives into calcite crystals allows one to embed non-native\nproprieties into the inorganic matrix and obtain new functional materials. Up\nto now, few parameters have been taken into account to evaluate the efficiency\nof inclusion of an additive. Taking inspiration from Nature, we grew calcite\ncrystals in the presence of fluorescent silica nanoparticles carrying different\nfunctional groups (PluS-X) to investigate the effect of surface chemistry on\nthe inclusion of the additives. PluS-X allowed us to keep constant all the\nparticle characteristics, including size, while changing exposed functional\ngroups and thus Zeta-potential. The effect on crystal morphology, the loading\nand distribution of PluS-X within the crystals have been evaluated with\ndifferent microscopy techniques. Our data indicate that hydroxyl functionalized\nparticles are entrapped more efficiently inside calcite single crystals without\ndistortion of the crystal structure and inhibition of the growth."
    },
    {
        "anchor": "Femtosecond laser driven molecular dynamics on surfaces: Photodesorption\n  of molecular oxygen from Ag(110): We simulate the femtosecond laser induced desorption dynamics of a diatomic\nmolecule from a metal surface by including the effect of the electron and\nphonon excitations created by the laser pulse. Following previous models, the\nlaser induced surface excitation is treated through the two temperature model,\nwhile the multidimensional dynamics of the molecule is described by a classical\nLangevin equation, in which the friction and random forces account for the\naction of the heated electrons. In this work, we propose the additional use of\nthe generalized Langevin oscillator model to also include the effect of the\nenergy exchange between the molecule and the heated surface lattice in the\ndesorption dynamics. The model is applied to study the laser induced desorption\nof O$_2$ from the Ag(110) surface, making use of a six-dimensional potential\nenergy surface calculated within density functional theory. Our results reveal\nthe importance of the phonon mediated process and show that, depending on the\nvalue of the electronic density in the surroundings of the molecule adsorption\nsite, its inclusion can significantly enhance or reduce the desorption\nprobabilities.",
        "positive": "Ambipolar Property of Isolated Hydrogen in Oxide Materials Revealed by\n  Muon: The study on the electronic state of muon as pseudo-hydrogen (represented by\nthe elemental symbol Mu) has long been appreciated as one of the few methods to\nexperimentally access the electronic state of dilute hydrogen (H) in\nsemiconductors and dielectrics. Meanwhile, theoretical predictions on the\nelectronic state of H in these materials by first-principles calculations using\ndensity functional theory (DFT) do not always agree with the observed states of\nMu, standing as an obstacle to integrating the findings of both Mu and H. In\nthis paper, we provide resolution to this problem by a semi-quantitative model\nthat enables systematic understanding of the electronic states of Mu in most\noxides."
    },
    {
        "anchor": "Subcoercive and multilevel ferroelastic remnant states with resistive\n  readout: Ferroelectric devices use their electric polarization ferroic order as the\nswitching and storage physical quantity for memory applications. However,\nadditional built-in physical quantities and memory paradigms are requested for\napplications. We propose here to take advantage of the multiferroic properties\nof ferroelectrics, using ferroelasticity to create a remnant strain, persisting\nafter stressing the material by converse piezoelectricity means. While large\nelectric fields are needed to switch the polarization, here writing occurs at\nsubcoercive much lower field values, which can efficiently imprint multiple\nremnant strain states. A proof-of-principle device, with the simplest and\nnon-optimized resistance strain detection design, is shown here to exhibit\n13-memory states of high reproducibility and reliability. The related\nadvantages in lower power consumption and limited device fatigue make our\napproach relevant for applications.",
        "positive": "Intrinsic Magnon Nernst Effects in Pyrochlore Iridate Thin Films: We theoretically study the magnon spin thermal transport using a strong\ncoupling approach in pyrochlore iridate trilayer thin films grown along the\n[111] direction. As a result of the Dzyaloshinskii-Moriya interaction (DMI),\nthe spin configuration of the ground state is an all-in/all-out ordering on\nneighboring tetrahedra of the pyrochlore lattice. In such a state, the system\nhas an inversion symmetry and a Nernst-type thermal spin current response is\nwell defined. We calculate the temperature dependence of the magnon Nernst\nresponse with respect to the magnon band topology controlled by the spin-orbit\ncoupling parameters and observe topologically protected chiral edge modes over\na range of parameters. Our study complements prior work on the magnon thermal\nHall effect in thin-film pyrochlore iridates and suggests that the [111] grown\nthin-film pyrochlore iridates are a promising candidate for thermal spin\ntransport and spin caloritronic devices."
    },
    {
        "anchor": "Empirical tight binding parameters for GaAs and MgO with explicit basis\n  through DFT mapping: The Empirical Tight Binding(ETB) method is widely used in atomistic device\nsimulations. The reliability of such simulations depends very strongly on the\nchoice of basis sets and the ETB parameters. The traditional way of obtaining\nthe ETB parameters is by fitting to experiment data, or critical theoretical\nbandedges and symmetries rather than a foundational mapping. A further\nshortcoming of traditional ETB is the lack of an explicit basis. In this work,\na DFT mapping process which constructs TB parameters and explicit basis from\nDFT calculations is developed. The method is applied to two materials: GaAs and\nMgO. Compared with the existing TB parameters, the GaAs parameters by DFT\nmapping show better agreement with the DFT results in bulk band structure\ncalculations and lead to different indirect valleys when applied to nanowire\ncalculations. The MgO TB parameters and TB basis functions are also obtained\nthrough the DFT mapping process.",
        "positive": "On the giant deformation and ferroelectricity of guanidinium nitrate: The extraordinary properties of materials accompanying their phase\ntransitions are exciting from the perspectives of scientific research and new\napplications. Most recently, Karothu et al.1 described guanidinium nitrate,\n[C(NH2)3]+[NO3]-, hereafter GN, as a ferroelectric semiconducting organic\ncrystal with exceptional actuating properties. However, the ferroelectric and\nsemiconducting properties of this hybrid organic-inorganic material were not\nconfirmed by the experimental results, and the reproducibility of the large\nstroke associated with the first-order transition is questionable, because the\nGN crystals are inherently susceptible to the formation of defects. Besides,\nprevious extensive studies on GN were not acknowledged."
    },
    {
        "anchor": "Characterization of crystal structure and precipitation crystallography\n  of a new MgxAl2-xGd phase in Mg97Al1Gd2 alloy: The composition, crystal structure and precipitation crystallography of a\nnewly found precipitate are characterized by a Cs-corrected scanning\ntransmission electron microscopy (STEM). The composition of the plate-like\nprecipitate could be expressed as MgxAl2-xGd (x = 0.38), and its crystal\nstructure is the same as the fcc type Laves phases Mg2Gd and Al2Gd with the\nlattice parameter of 7.92 Angstrom (space group No. 227, Fd-3m). The\norientation relationship between the matrix and precipitate is found to be\n(0001)m // (111)p and [10-10]m // [1-10]p, and the habit plane is parallel to\n(0001)m // (111)p plane. In addition, this preferred crystallography of phase\ntransformation is well explained based on the atomic matching in the interface.",
        "positive": "Graphene-Passivated Nickel as an Oxidation-Resistant Electrode for\n  Spintronics: We report on graphene-passivated ferromagnetic electrodes (GPFE) for spin\ndevices. GPFE are shown to act as spin-polarized oxidation-resistant\nelectrodes. The direct coating of nickel with few layer graphene through a\nreadily scalable chemical vapour deposition (CVD) process allows the\npreservation of an unoxidized nickel surface upon air exposure. Fabrication and\nmeasurement of complete reference tunneling spin valve structures demonstrates\nthat the GPFE is maintained as a spin polarizer and also that the presence of\nthe graphene coating leads to a specific sign reversal of the\nmagneto-resistance. Hence, this work highlights a novel oxidation-resistant\nspin source which further unlocks low cost wet chemistry processes for\nspintronics devices."
    },
    {
        "anchor": "Molecular Beam Epitaxy of thin HfTe2 semimetal films: Epitaxial thin films of 1T-HfTe2 semimetal are grown by MBE on AlN(0001)\nsubstrates. The measured in-plane lattice parameter indicates an unstrained\nfilm which is also azimuthally aligned with the AlN substrate, albeit with an\nin-plane mosaic spread, as it would be expected for van der Waals epitaxy.\nAngle resolved photoemission spectroscopy combined with first principles\nelectronic band structure calculations show steep linearly dispersing\nconduction and valence bands which cross near the Brillouin zone center,\nproviding evidence that HfTe2 /AlN is an epitaxial topological Dirac semimetal.",
        "positive": "Ferromagnetic one dimensional Ti atomic chain: Using the full potential linearized augmented plane wave (FLAPW) method, we\nhave explored the magnetic properties of one dimensional (1D) Ti atomic chain.\nAstonishingly, we for the first time observed that the 1D Ti atomic chain has\nferromagnetic ground state even on NiAl(110) surface although the Ti has no\nmagnetic moment in bulk or macroscopic state. It was found that the physical\nproperty of direct exchange interaction among Ti atoms occurred in free\nstanding state is well preserved on NiAl(110) surface and this feature has an\nessential role in ferromagnetism of 1D Ti atomic chain. It was shown that the\nm=$|2|$ state has the largest contribution to the magnetic moment of Ti atom\ngrown on NiAl(110) surface. In addition, we found that the magnetic dipole\ninteraction is a key factor in the study of magnetic anisotropy, not the\nmagnetocrystalline anisotropy arising from spin-orbit interaction."
    },
    {
        "anchor": "Nature of Adsorption on TiC(111): Extensive density-functional calculations are performed for chemisorption of\natoms in the three first periods (H, B, C, N, O, F, Al, Si, P, S, and Cl) on\nthe polar TiC(111) surface. Calculations are also performed for O on TiC(001),\nfor full O(1x1) monolayer on TiC(111), as well as for bulk TiC and for the\nclean TiC(111) and (001) surfaces. Detailed results concerning atomic\nstructures, energetics, and electronic structures are presented. For the bulk\nand the clean surfaces, previous results are confirmed. In addition, new\ndetailed results are given on the presence of C-C bonds in the bulk and at the\nsurface, as well as on the presence of a Ti-based surface resonance (TiSR) at\nthe Fermi level and of C-based surface resonances (CSR's) in the lower part of\nthe surface upper valence band (UVB). For the adsorption, adsorption energies\nE_ads and relaxed geometries are presented, showing great variations\ncharacterized by pyramid-shaped E_ads trends within each period. An\nextraordinarily strong chemisorption is found for the O atom, 8.8 eV/adatom. On\nthe basis of the calculated electronic structures, a concerted-coupling model\nfor the chemisorption is proposed, in which two different types of\nadatom-substrate interactions work together to provide the obtained strong\nchemisorption: (i) adatom-TiSR and (ii) adatom-CSR's. This model is used to\nsuccessfully describe the essential features of the calculated E_ads trends.\nThe fundamental nature of this model, based on the Newns-Anderson model, should\nmake it apt for general application to transition-metal carbides and nitrides,\nand for predictive purposes in technological applications, like cutting-tool\nmultilayer coatings and MAX phases.",
        "positive": "Coevolutionary search for optimal materials in the space of all possible\n  compounds: Over the past decade, evolutionary algorithms, data mining, and other methods\nshowed great success in solving the main problem of theoretical\ncrystallography: finding the stable structure for a given chemical composition.\nHere we develop a method that addresses the central problem of computational\nmaterials science: the prediction of material(s), among all possible\ncombinations of all elements, that possess the best combination of target\nproperties. This nonempirical method combines our new coevolutionary approach\nwith the carefully restructured \"Mendelevian\" chemical space, energy filtering,\nand Pareto optimization to ensure that the predicted materials have optimal\nproperties and a high chance to be synthesizable. The first calculations,\npresented here, illustrate the power of this approach. In particular, we find\nthat diamond (and its polytypes, including lonsdaleite) are the hardest\npossible materials and that bcc-Fe has the highest zero-temperature\nmagnetization among all possible compounds."
    },
    {
        "anchor": "Investigation of oxygen-vacancy complexes in diamond by means of\n  \\textit{ab initio} calculations: Point defects in diamond may act as quantum bits. Recently, oxygen-vacancy\nrelated defects have been proposed to the origin of the so-called ST1 color\ncenter in diamond that can realize a long-living solid-state quantum memory.\nMotivated by this proposal we systematically investigate oxygen-vacancy\ncomplexes in diamond by means of first principles density functional theory\ncalculations. We find that all the considered oxygen-vacancy defects have a\nhigh-spin ground state in their neutral charge state, which disregards them as\nan origin for the ST1 color center. We identify a high-spin metastable\noxygen-vacancy complex and characterize their magnetooptical properties for\nidentification in future experiments.",
        "positive": "Dielectric layer dependent surface plasmon effect of metallic\n  nanoparticles on silicon substrate: The electromagnetic interaction between Ag nanoparticles on the top of the Si\nsubstrate and the incident light has been studied by numerical simulations. It\nis found that the presence of a dielectric layer with different thickness leads\nto varied resonance wavelength and scattering cross section, and consequently\nshifted photocurrent response over all wavelengths. These different behaviors\nare determined by whether the dielectric layer is beyond the domain where the\nnear field of nanoparticles takes effect, and geometrical optics effects must\nbe taken into account. It is revealed that for particle of a certain size, an\nappropriate dielectric layer thickness is desirable to achieve the best\nabsorption performance. For a certain thickness of dielectric layer, an\nappropriate granular size is also desirable. These observations have\nsubstantial applications for the optimization of surface plasmon enhanced\nsilicon solar cells."
    },
    {
        "anchor": "Influence of Carbon Content on the Crystallographic Structure of Boron\n  Carbide Films: Boron carbide thin films were synthesised by laser-assisted chemical vapour\ndeposition (LCVD), using a CO2 laser beam and boron trichloride and methane as\nprecursors. Boron and carbon contents were measured by electron probe\nmicroanalysis (EPMA). Microstructural analysis was carried out by Raman\nmicrospectroscopy and glancing incidence X-ray diffraction (GIXRD) was used to\nstudy the crystallographic structure and to determine the lattice parameters of\nthe polycrystalline films. The rhombohedral-hexagonal boron carbide crystal\nlattice constants were plotted as a function of the carbon content, and the\nnon-linear observed behaviour is interpreted on the basis of the complex\nstructure of boron carbide.\n  Keywords: Boron carbide; Laser CVD; crystallographic structure; micro-Raman\nspectroscopy.",
        "positive": "The morphology and temperature dependent tensile properties of diamond\n  nanothreads: The ultrathin one-dimensional sp3 diamond nanothreads (NTHs), as successfully\nsynthesised recently, have greatly augmented the interests from the carbon\ncommunity. In principle, there can exist different stable NTH structures. In\nthis work, we studied the mechanical behaviours of three representative NTHs\nusing molecular dynamics simulations. It is found that the mechanical\nproperties of NTH can vary significantly due to morphology differences, which\nare believed to originate from the different stress distributions determined by\nits structure. Further studies have shown that the temperature has a\nsignificant impact on the mechanical properties of the NTH. Specifically, the\nfailure strength/strain decreases with increasing temperature, and the\neffective Young's modulus appears independent of temperature. The remarkable\nreduction of the failure strength/strain is believed to be resulted from the\nincreased bond re-arrangement process and free lateral vibration at high\ntemperatures. In addition, the NTH is found to have a relatively high bending\nrigidity, and behaves more like flexible elastic rod. This study highlights the\nimportance of structure-property relation and provides a fundamental\nunderstanding of the tensile behaviours of different NTHs, which should shed\nlight on the design and also application of the NTH-based nanostructures as\nstrain sensors and mechanical connectors."
    },
    {
        "anchor": "High-entropy ceramics: propelling applications through disorder: Disorder enhances desired properties, as well as creating new avenues for\nsynthesizing materials. For instance, hardness and yield stress are improved by\nsolid-solution strengthening, a result of distortions and atomic size\nmismatches. Thermo-chemical stability is increased by the preference of\nchemically disordered mixtures for high-symmetry super-lattices. Vibrational\nthermal conductivity is decreased by force-constant disorder without\nsacrificing mechanical strength and stiffness. Thus, high-entropy ceramics\npropel a wide range of applications: from wear resistant coatings and thermal\nand environmental barriers to catalysts, batteries, thermoelectrics and nuclear\nenergy management. Here, we discuss recent progress of the field, with a\nparticular emphasis on disorder-enhanced properties and applications.",
        "positive": "Magnetocaloric performance of RE$_{11}$Co$_4$In$_9$ (RE = Tb, Er): The magnetocaloric effect in RE$_{11}$Co$_4$In$_9$ (RE = Tb, Er) has been\nstudied by means of magnetometric measurements in the function of temperature\nand applied magnetic field. The maximum magnetic entropy change ($-\\Delta\nS_{\\mathrm{M}}^{\\mathrm{max}}$) at magnetic flux density change\n($\\Delta\\mu_{0}H$) 0-9 T has been determined to be 5.51\nJ$\\cdot$kg$^{-1}\\cdot$K$^{-1}$ at 47.4 K for Tb$_{11}$Co$_4$In$_9$ and 14.28\nJ$\\cdot$kg$^{-1}\\cdot$K$^{-1}$ at 12.3 K for Er$_{11}$Co$_4$In$_9$, while\ntemperature averaged entropy change (TEC) with 3 K span equals 5.50 and 14.14\nJ$\\cdot$kg$^{-1}\\cdot$K$^{-1}$ for RE = Tb and Er, respectively. The relative\ncooling power (RCP) and refrigerant capacity (RC) equal respectively 522.1 and\n391.2 J$\\cdot$kg$^{-1}$ in Tb$_{11}$Co$_4$In$_9$ and 605.2 and 463.1\nJ$\\cdot$kg$^{-1}$ in Er$_{11}$Co$_4$In$_9$."
    },
    {
        "anchor": "Ultrafast Electronic Dynamics of a Weyl Semimetal MoTe$_2$ Revealed by\n  Time and Angle Resolved Photoemission Spectroscopy: A Weyl semimetal is a new type of topological quantum phase with intriguing\nphysics near the Weyl nodes. Although the equilibrium state of Weyl semimetals\nhas been investigated, the ultrafast dynamics near the Weyl node in the\nnonequilibrium state is still missing. Here by performing time and angle\nresolved photoemission spectroscopy on type-II Weyl semimetal MoTe$_2$, we\nreveal the dispersion of the unoccupied states and identify the Weyl node at 70\nmeV above E$_F$. Moreover, by tracking the ultrafast relaxation dynamics near\nthe Weyl node upon photo-excitation with energy, momentum and temporal\nresolution, two intrinsic recovery timescales are observed, a fast one of 430\nfs and a slow one of 4.1 ps, which are associated with hot electron cooling by\noptical phonon cascade emission and anharmonic decay of hot optical phonons\nrespectively. The electron population shows a metallic response, and the two\ntemperature model fitting of the transient electronic temperature gives an\nelectron-phonon coupling constant of $\\lambda\\langle\\Omega^2\\rangle\\simeq32$\n$\\textrm{meV}^2$. Our work provides important dynamic information for\nunderstanding the relaxation mechanism of a Weyl semimetal and for exploiting\npotential applications using ultrafast optical control.",
        "positive": "Donor-acceptor co-adsorption ratio controls structure and electronic\n  properties of two-dimensional alkali-organic networks on Ag(100): The results are presented of a detailed combined experimental and theoretical\ninvestigation of the influence of coadsorbed electron-donating alkali atoms and\nthe prototypical electron acceptor molecule TCNQ\n(7,7,8,8-tetracyanoquinodimethane) on the Ag(100) surface. Several coadsorption\nphases were characterised by scanning tunnelling microscopy, low energy\nelectron diffraction, and soft-X-ray photoelectron spectroscopy. Quantitative\nstructural data were obtained using normal incidence X-ray standing wave\n(NIXSW) measurements and compared with the results of density functional theory\n(DFT) calculations using several different methods of dispersion correction.\nGenerally good agreement between theory and experiment was achieved for the\nquantitative structures, albeit with prediction of the alkali atom heights\nbeing challenging for some methods. The adsorption structures depend\nsensitively on the interplay of molecule-metal charge transfer and long-range\ndispersion forces, which are controlled by the composition ratio between alkali\natoms and TCNQ. The large difference in atomic size between K and Cs has\nnegligible effects on stability, whereas increasing the ratio of K:TCNQ from\n1:4 to 1:1 leads to a weakening of molecule-metal interaction strength in\nfavour of stronger ionic bonds within the two-dimensional alkali-organic\nnetwork. A strong dependence of the work function on the alkali donor-TCNQ\nacceptor co-adsorption ratio is predicted."
    },
    {
        "anchor": "Imaging graphene moir\u00e9 superlattices via scanning Kelvin probe\n  microscopy: Moir\\'e superlattices in van der Waals heterostructures are gaining\nincreasing attention because they offer new opportunities to tailor and explore\nunique electronic phenomena when stacking 2D materials with small twist angles.\nHere, we reveal local surface potentials associated with stacking domains in\ntwisted double bilayer graphene (TDBG) moir\\'e superlattices. Using a\ncombination of both lateral Piezoresponse Force Microscopy (LPFM) and Scanning\nKelvin Probe Microscopy (SKPM), we distinguish between Bernal (ABAB) and\nrhombohedral (ABCA) stacked graphene and directly correlate these stacking\nconfigurations with local surface potential. We find that the surface potential\nof the ABCA domains is ~15 mV higher (smaller work function) than that of the\nABAB domains. First-principles calculations based on density functional theory\nfurther show that the different work functions between ABCA and ABAB domains\narise from the stacking dependent electronic structure. We show that, while the\nmoir\\'e superlattice visualized by LPFM can change with time, imaging the\nsurface potential distribution via SKPM appears more stable, enabling the\nmapping of ABAB and ABCA domains without tip-sample contact-induced effects.\nOur results provide a new means to visualize and probe local domain stacking in\nmoir\\'e superlattices along with its impact on electronic properties.",
        "positive": "Effect of Surface Roughness on Early Stage Oxidation Behavior of Ni-Base\n  Superalloy IN 625: In the present work the effect of surface roughness on oxidation behavior\nduring the early stages of high temperature exposure of Ni-base superalloy IN\n625 is described. The surface roughness was described using standard contact\nprofilometer as well as novel method, fractal analysis. It was found that the\ndifferent surface preparation resulted in a difference in roughness with a\nparameter increase of at least one order of magnitude for the ground sample as\ncompared with the polished sample. The oxidation test was performed in a\nhorizontal tube furnace. Post exposure analyses including glow discharge\noptical emission spectrometry (GD OES) and scanning electron microscopy (SEM),\nwhich revealed that grinding lowers the oxidation kinetics of IN 625. It was\nfound that surface preparation influences the oxide scale composition and\nmorphology. The hypothesis explaining the mechanism responsible for the changes\nin oxidation behavior is proposed as well."
    },
    {
        "anchor": "Exploring Exciton and Polaron Dominated Photo-physical Phenomena in\n  Ruddlesden-Popper Phases of Ban+1ZrnS3n+1 (n=[1-3]) from Many Body\n  Perturbation Theory: Ruddlesden-Popper (RP) phases of\nBa$_{\\textrm{n+1}}$Zr$_{\\textrm{n}}$S$_{\\textrm{3n+1}}$ (n=[1-3]) are evolved\nas new promising class of chalcogenide perovskites in the field of\noptoelectronics, especially in solar cells. However, detailed studies regarding\nits optical, excitonic, polaronic and transport properties are hitherto\nunknown. Here, we have explored the excitonic and polaronic effect in RP phases\nof Ba$_{\\textrm{n+1}}$Zr$_{\\textrm{n}}$S$_{\\textrm{3n+1}}$ (n=[1-3]) using\nseveral first-principles based state-of-the-art methodologies under the\nframework of Many Body Perturbation Theory. Unlike it's bulk counterpart, the\noptical and excitonic anisotropy are observed in\nBa$_{\\textrm{n+1}}$Zr$_{\\textrm{n}}$S$_{\\textrm{3n+1}}$ (n=[1-3]) RP phases.\nFrom Wannier-Mott approach, we show that in the RP phases of this class of\nchalcogenide perovskites, capturing the ionic contribution to the dielectric\nconstant is important. We report significant ionic contribution and relatively\nsmaller electron-phonon coupling constant for\nBa$_{\\textrm{n+1}}$Zr$_\\textrm{n}$S$_{\\textrm{3n+1}}$ in comparison to the bulk\nBaZrS$_3$. The exciton binding energy is found to be dependent on the presence\nof large electron-phonon coupling. The charge carrier mobility is maximum in\nBa$_2$ZrS$_4$, computed employing deformation potential of the same. As per our\nanalysis, the optical phonon modes are observed to dominate the acoustic phonon\nmodes, leading to decrease in polaron mobility on increasing n in\nBa$_{\\textrm{n+1}}$Zr$_{\\textrm{n}}$S$_{\\textrm{3n+1}}$ (n=[1-3]).",
        "positive": "Origin of the exotic electronic states in antiferromagnetic NdSb: Using angle resolved photoemission spectroscopy measurements and first\nprinciple calculations, we report that the possible unconventional 2q\nantiferromagnetic (AFM) order in NdSb can induce unusual modulation on its\nelectronic structure. The obvious extra bands observed in the AFM phase of NdSb\nare well reproduced by theoretical calculations, in which the Fermi-arc-like\nstructures and sharp extra bands are originated from the in-gap surface states.\nHowever, they are demonstrated to be topological trivial. By tuning the\nchemical potential, the AFM phase of NdSb would go through a topological phase\ntransition, realizing a magnetic topological insulator phase. Hence, our study\nsheds new light on the rare earth monopnictides for searching unusual AFM\nstructure and the potential of intrinsic magnetic topological materials."
    },
    {
        "anchor": "Magnetoactive elastomer based on superparamagnetic nanoparticles with\n  Curie point close to room temperature: A magnetoactive elastomer (MAE) consisting of single-domain La0.8Ag0.2Mn1.2O3\nnanoparticles with a Curie temperature close to room temperature (TC = 308 K)\nin a silicone matrix has been prepared and comprehensively studied. It has been\nfound that at room temperature and above, MAE particles are magnetized\nsuperparamagnetically with a low coercivity below 10 Oe, and the influence of\nmagnetic anisotropy on the appearance of a torque is justified. A coupling\nbetween magnetization and magnetoelasticity has been also established. The\nmechanisms of the appearance of magnetoelasticity, including the effect of MAE\nrearrangement and MAE compression by magnetized particles, have been revealed.\nIt has been found that the magnetoelastic properties of MAE have critical\nfeatures near TC. The magnetoelastic properties of MAE disappear at T > TC and\nare restored at T < TC. This makes it possible to use MAE at room temperature\nas a smart material for devices with self-regulating magnetoelastic properties.",
        "positive": "Single-shot multi-level all-optical magnetization switching mediated by\n  spin-polarized hot electron transport: All-optical ultrafast magnetization switching in magnetic material thin film\nwithout the assistance of an applied external magnetic field is being explored\nfor future ultrafast and energy-efficient magnetic storage and memories. It has\nbeen shown that femto-second light pulses induce magnetization reversal in a\nlarge variety of magnetic materials. However, so far, only GdFeCo-based\nferrimagnetic thin films exhibit magnetization switching via a single optical\npulse. Here we demonstrate the single-pulse switching of Co/Pt multilayers\nwithin a magnetic spin-valve structure ([Co/Pt] / Cu / GdFeCo) and further show\nthat the four possible magnetic configurations of the spin valve can be\naccessed using a sequence of single femto-second light pulses. Our experimental\nstudy reveals that the magnetization final state of the ferromagnetic [Co/Pt]\nlayer is determined by spin-polarized hot electrons generated by the light\npulse interactions with the GdFeCo layer. This work provides a new approach to\ndeterministically switch ferromagnetic layers and a pathway to engineering\nmaterials for opto-magnetic multi-bit recording."
    },
    {
        "anchor": "Machine Learning methods for interatomic potentials: application to\n  boron carbide: Total energies of crystal structures can be calculated to high precision\nusing quantum-based density functional theory (DFT) methods, but the\ncalculations can be time consuming and scale badly with system size. Cluster\nexpansions of total energy as a linear superposition of pair, triplet and\nhigher interactions can efficiently approximate the total energies but are best\nsuited to simple lattice structures. To model the total energy of boron\ncarbide, with a complex crystal structure, we explore the utility of machine\nlearning methods ($L_1$-penalized regression, neural network, Gaussian process\nand support vector regression) that capture certain non-linear effects\nassociated with many-body interactions despite requiring only pair frequencies\nas input. Our interaction models are combined with Monte Carlo simulations to\nevaluate the thermodynamics of chemical ordering.",
        "positive": "Affordable inline structuration measurements of printable mortar with a\n  pocket shear vane: The control of mortar rheology is of paramount importance in the design of\nsystems and structures in 3D printing concrete by extrusion. This is\nparticularly sensitive for two-component (2K) processes that use an accelerator\nto switch the printed mortar very quickly from a liquid behavior to a\nsufficiently solid behavior to be able to be printed. It is necessary to set up\nsimple and effective tests within a precise methodological framework to qualify\nmaterials evolving so quickly in an industrial context. It is obvious that\ninline solutions, that is to say, post-printing solutions, will be more\ndesirable than benchtop-type solutions reproducing the printing conditions as\nwell as possible, but imperfectly. After some main key points about measuring\nthe structuration of mortars, we propose an original inline test using a pocket\nshear vane tester. The protocols are precisely described and the simplicity and\nquality of the results are demonstrated."
    },
    {
        "anchor": "Defect topology and annihilation by cooperative cascading movement of\n  atoms in highly neutron irradiated graphite: Graphite has been used as neutron moderator or reflector in many nuclear\nreactors. The irradiation of graphite in a nuclear reactor results in a complex\npopulation of defects. Heating of the irradiated graphite at high temperatures\nresults in annihilation of the defects with release of an unusually large\nenergy, called the Wigner energy. From various experiments on highly irradiated\ngraphite samples from CIRUS reactor at Trombay and ab-initio simulations, we\nhave for the first time identified various 2-, 3- and 4-coordinated topological\nstructures in defected graphite, and provided microscopic mechanism of defect\nannihilation on heating and release of the Wigner energy. The annihilation\nprocess involves cascading cooperative movement of atoms in two steps involving\nan intermediate structure. Our work provides new insights in understanding of\nthe defect topologies and annihilation in graphite which is of considerable\nimportance to wider areas of graphitic materials including graphene and carbon\nnanotubes.",
        "positive": "Impact of misfit strain on the properties of tetragonal Pb(Zr,Ti)O3 thin\n  film heterostructures: Heterostructures consisting of PbZr0.2Ti0.8O3 and PbZr0.4Ti0.6O3 films grown\non a SrTiO3 (100) substrate with a SrRuO3 bottom electrode were prepared by\npulsed laser deposition. Using the additional interface provided by the\nferroelectric bilayer structure and changing the sequence of the layers, the\ndislocation content and domain patterns were varied. The resulting\nmicrostructure was investigated by transmission electron microscopy.\nMacroscopic ferroelectric measurements have shown a large impact of the\nformation of dislocations and the a/c domain structure on the ferroelectric\npolarization and dielectric constant. A thermodynamic analysis using the\nLANDAU-GINZBURG-DEVONSHIRE approach that takes into account the ratio of the\nthicknesses of the two ferroelectric layers and electrostatic coupling is used\nto describe the experimental data."
    },
    {
        "anchor": "Absence of Structural Impact of Noble Nanoparticles on P3HT: PCBM Blends\n  for Plasmon Enhanced Bulk-Heterojunction Organic Solar Cells Probed by\n  Synchrotron Grazing Incidence X-Ray Diffraction: The incorporation of noble metal nanoparticles, displaying localized surface\nplasmon resonance, in the active area of donor-acceptor bulk-heterojunction\norganic photovoltaic devices is an industrially compatible light trapping\nstrategy, able to guarantee better absorption of the incident photons and give\nan efficiency improvement between 12% and 38%. In the present work, we\ninvestigate the effect of Au and Ag nanoparticles blended with P3HT: PCBM on\nthe P3HT crystallization dynamics by synchrotron grazing incidence X-ray\ndiffraction. We conclude that the presence of (1) 80nm Au, (2) mix of 5nm,\n50nm, 80nm Au, (3) 40nm Ag, and (4) 10nm, 40nm, 60nm Ag colloidal\nnanoparticles, at different concentrations below 0.3 wt% in P3HT: PCBM blends,\ndoes not affect the behaviour of the blends themselves.",
        "positive": "Investigation of the phase occurrence and H sorption properties in the\n  Y33.33Ni66.67-xAlx (0 <= x <= 33.33) system: The Y33.33Ni66.67-xAlx system has been investigated in the region 0 <= x <=\n33.3. The alloys were synthesized by induction melting. Phase occurrence and\nstructural properties were studied by X-Ray powder Diffraction (XRD). The Al\nsolubility in each phase has been investigated by XRD and Electron Probe\nMicro-Analysis (EPMA). The hydrogenation properties were characterized by\npressure-composition isotherm measurements and kinetic curves at 473 K. For x =\n0, the binary Y33.33Ni66.67 alloy crystallizes in the cubic superstructure with\nF4-3m space group and ordered Y vacancies. For 1.67 <= x <= 8.33, the alloys\ncontain mainly Y(Ni, Al)2 and Y(Ni, Al)3 pseudobinary phases; while for 16.67\n<= x <= 33.33 they are mainly formed by ternary line compounds Y3Ni6Al2,\nY2Ni2Al and YNiAl. Contrary to the binary Y33.33Ni66.67, Y(Ni, Al)2\npseudo-binary compounds crystalize in C15 phase (space group Fd-3m ) with\ndisordered Y vacancies. The solubility limit of Al in the C15 YNi2-yAly phase\nis y = 0.11 (i.e., x = 3.67). The Y(Ni, Al)3 phase changes from rhombohedral\n(PuNi3-type, R-3m) to hexagonal (CeNi3-type, P63/mmc) structure for x\nincreasing from 5.00 to 6.67. Upon hydrogenation, the disproportion of C15\nY(Ni, Al)2 and losses of crystallinity of YNi and Y2Ni2Al are the main reasons\ncausing capacity decay of Y33.33Ni66.67-xAlx (0 <= x <= 33.33) alloys upon\ncycling."
    },
    {
        "anchor": "Enhanced Gilbert Damping in Re doped FeCo Films: A Combined Experimental\n  and Theoretical Study: The effects of rhenium doping in the range 0 to 10 atomic percent on the\nstatic and dynamic magnetic properties of Fe65Co35 thin films have been studied\nexperimentally as well as with first principles electronic structure\ncalculations focusing on the change of the saturation magnetization and the\nGilbert damping parameter. Both experimental and theoretical results show that\nthe saturation magnetization decreases with increasing Re doping level, while\nat the same time Gilbert damping parameter increases. The experimental low\ntemperature saturation magnetic induction exhibits a 29 percent decrease, from\n2.31 T to 1.64 T, in the investigated doping concentration range, which is more\nthan predicted by the theoretical calculations. The room temperature value of\nthe damping parameter obtained from ferromagnetic resonance measurements,\ncorrecting for extrinsic contributions to the damping, is for the undoped\nsample 0.0027, which is close to the theoretically calculated Gilbert damping\nparameter. With 10 atomic percent Re doping, the damping parameter increases to\n0.0090, which is in good agreement with the theoretical value of 0.0073. The\nincrease in damping parameter with Re doping is explained by the increase in\ndensity of states at Fermi level, mostly contributed by the spin-up channel of\nRe. Moreover, both experimental and theoretical values for the damping\nparameter are observed to be weakly decreasing with decreasing temperature.",
        "positive": "High-pressure hydrothermal growth and characterization of Sr3Os4O14\n  single crystals: Single crystals of the novel strontium osmate Sr3Os4O14 have been grown by\nthe hydrothermal method using opposed anvil high-pressure and high-temperature\ntechnique. The reaction took place in sealed gold capsules at 3 GPa and a\ntemperature of 1100 C, with water acting as a solvent. The employed method\nyields up to 1 mm crystals with quite uncommon double-terminated morphologies.\nThe crystal structure was identified as tetragonal by single-crystal X-ray\ndiffraction, with lattice parameters a = 12.2909(8) A and c = 7.2478(5) A. The\nstructural analysis suggests P42nm or P42/mnm as a possible space group. In\ngeneral, the structure belongs to the pyrochlore type and is composed of a\nnetwork of symmetrically arranged OsO6 octahedra. Resistivity measurements\nevidence a metallic behavior, accompanied by a temperature-independent\nparamagnetism. Heat capacity measurements reveal a slightly enhanced value of\nthe Sommerfeld coefficient 34 mJ/mol K2. Superconductivity has not been\nobserved down to 2 K."
    },
    {
        "anchor": "Ultra-clean isotope engineered double-walled carbon nanotubes as\n  tailored hosts to trace the growth of carbyne: Increasing attention is currently given to carbyne, the sp1 hybridized\none-dimensional carbon allotrope, because of its predicted outstanding\nmechanical, optical, and electrical properties. Although recently substantial\nprogress has been reported on confined carbyne synthesized inside double-walled\ncarbon nanotubes (DWCNTs), its formation mechanism and precursors for growth\nremain elusive. Here, we show a rational design of isotope engineered\nultra-clean DWCNTs as tailored hosts to trace the growth of carbyne, which\nallows to identify the precursor and unravel the formation mechanism of carbyne\nduring high-vacuum annealing at high-temperatures. Using this approach,\nultra-clean DWCNTs with 80.4% 13C-enriched inner walls and outer tubes of\nnaturally abundant served to unambiguously prove that only the carbonaceous\nmaterials inside the DWCNTs can act as precursors. The exchange of C atoms\nbetween inner and outer tubes happens without any growth of carbyne. After\napplying a secondary oxidation step, it is possible to produce the carbonaceous\nprecursors from the partially oxidized DWCNTs. In this manner, not only carbyne\nwith a record of ~28.8% 13C enrichment is grown, but concomitant healing,\nreorganization and regrowth of the DWCNTs occurs. This work enables to identify\nthe precursor and trace the growth mechanism of confined carbyne with\nengineered properties. This is a crucial step, towards accessing the full\napplication potential of confined carbyne hybrids by tailoring not only the\nisotopic fillers, but also the inner and outer tubes of the DWCNT hosts.",
        "positive": "Non-destructive characterization techniques for battery performance and\n  lifecycle assessment: As global energy demands escalate, and the use of non-renewable resources\nbecome untenable, renewable resources and electric vehicles require far better\nbatteries to stabilize the new energy landscape. To maximize battery\nperformance and lifetime, understanding and monitoring the fundamental\nmechanisms that govern their operation throughout their life cycle is crucial.\nUnfortunately, from the moment batteries are sealed until their end-of-life,\nthey remain a black box, and our current knowledge of a commercial battery s\nhealth status is limited to current (I), voltage (V), temperature (T), and\nimpedance (R) measurements, at the cell or even module level during use.\nElectrochemical models work best when the battery is new, and as state\nreckoning drifts leading to an over-reliance on insufficient data to establish\nconservative safety margins resulting in the systematic under-utilization of\ncells and batteries. While the field of operando characterization is not new,\nthe emergence of techniques capable of tracking commercial battery properties\nunder realistic conditions has unlocked a trove of chemical, thermal, and\nmechanical data that has the potential to revolutionize the development and\nutilization strategies of both new and used lithium-ion devices. In this\nreview, we examine the latest advances in non-destructive operando\ncharacterization techniques, including electrical sensors, optical fibers,\nacoustic transducers, X-ray-based imaging and thermal imaging (IR camera or\ncalorimetry), and their potential to improve our comprehension of degradation\nmechanisms, reduce time and cost, and enhance battery performance throughout\nits life cycle."
    },
    {
        "anchor": "Ab-initio study of gap opening and screening effects in gated bilayer\n  graphene: The electronic properties of doped bilayer graphene in presence of bottom and\ntop gates have been studied and characterized by means of Density Functional\nTheory calculations. Varying independently the bottom and top gates it is\npossible to control separately the total doping charge on the sample, and the\naverage external electric field acting on the bilayer. We show that, at fixed\ndoping level, the band gap at the K point in the Brillouin zone depends\nlinearly on the average electric field, whereas the corresponding\nproportionality coefficient has a non-monotonic dependence on doping. We find\nthat the DFT-calculated band gap at K, for small doping levels, is roughly half\nof the band gap obtained with standard Tight Binding approach. We show that\nthis discrepancy arises from an underestimate, in the TB model, of the\nscreening of the system to the external electric field. In particular, on the\nbasis of our DFT results we observe that, when the bilayer graphene is in\npresence of an external electric field, both an interlayer and an intralayer\nscreening occur. Only the interlayer screening is included in TB calculations,\nwhile both screenings are fundamental for the description of the band gap\nopening. We finally provide a general scheme to obtain the full band structure\nof the gated bilayer graphene, for an arbitrary value of the external electric\nfield and of the doping.",
        "positive": "A Theoretical Study Of Elastic, Electronic, Optical and Thermodynamic\n  Properties Of AlB2 AND TaB2: Using ab initio method we have studied the structural, elastic, electronic,\noptical and thermodynamic properties of AlB2 and TaB2. We have used plane wave\npseudopotential with generalised gradient approximation as implemented in\nCASTEP program. The independent elastic constants, bulk modulus, Young's\nmodulus, shear modulus, anisotropic factor, Pugh ratio, etc are calculated.\nThis results show that AlB2 and TaB2 are mechanically stable. We have also\ncalculated the band structure and density of states. Band structure results\nshow that AlB2 and TaB2 show metallic behaviour. In order to understand the\nelectronic properties in a better way we have also calculated dielectric\nfunction, refractive index, absorption coefficient, conductivity, loss function\nand reflectivity. Results of absorption coefficient and conductivity are in\ngood agreement with the band structure results. The effect of temperature and\npressure on the bulk modulus, Debye temperature, specific heat and also on the\nthermal expansion coefficient are derived from the quasi-harmonic Debye model\nwith phononic effect in both cases.The results for the elastic and electronic\nproperties are compared to experimental measurements and with the results\nobtained in different band-structure calculations, however, no optical data are\navailable for comparison."
    },
    {
        "anchor": "Observation of three-state nematicity and domain evolution in\n  atomically-thin antiferromagnetic NiPS3: Nickel phosphorus trisulfide (NiPS3), a van der Waals (vdW) 2D\nantiferromagnet, has captivated enormous attention for its intriguing physics\nin recent years. However, despite its fundamental importance in physics of\nmagnetism and promising potential for technological applications, the study of\nmagnetic domains in NiPS3 down to atomically thin is still lacking. Here, we\nreport the layer-dependent magnetic characteristics and magnetic domains within\nantiferromagnetic NiPS3 by employing linear dichroism (LD) combined with\npolarized microscopy, spin-correlated photoluminescence (PL), and Raman\nspectroscopy. Our results reveal the existence of the\nparamagnetic-to-antiferromagnetic phase transition in bulk to bilayer NiPS3\nwith stronger spin fluctuation in thinner NiPS3. Furthermore, our study\nidentifies three distinct antiferromagnetic domains within atomicallythin NiPS3\nand captures the thermally-activated domain evolution. Our findings provide\ncrucial insights for the development of antiferromagnetic spintronics and\nrelated technologies.",
        "positive": "Role of interface reaction on resistive switching of Metal/a-TiO2/Al\n  RRAM devices: For the clear understanding of the role of interface reaction between top\nmetal electrode and titanium oxide layer, we investigated the effects of\nvarious top metals on the resistive switching in Metal/a-TiO2/Al devices. The\ntop Al device with the highest oxygen affinity showed the best memory\nperformance, which is attributed to the fast formation of interfacial layer\n(Al-Ti-O), as confirmed by high resolution transmission electron microscopy and\nelectron dispersive spectroscopy. Hence, we concluded that the interface layer,\ncreated by the redox reaction between top metal electrode and TiO2 layer, plays\na crucial role in bipolar resistive switching behaviors of metal/TiO2/Al\nsystems."
    },
    {
        "anchor": "Internal Structure of Metal Vacancies in Cubic Carbides: A combinatorial approach is employed to investigate the atomic and electronic\nstructures of a metal vacancy in titanium carbide. It turns out that the usual\nrelaxed geometry of the vacancy is just a metastable state representing a local\nenergy minimum. Using ab initio calculations and by systematically searching\nthrough the configurational space of a Ti monovacancy, we identify a multitude\nof local minima with reconstructed geometry that are lower in energy. Among\nthem, there is a planar configuration with two displaced carbons forming a\ndimer inside the vacancy. This structure has the optimal number and order of\nC-C bonds making it the global minimum. Further calculations show that this\nreconstructed geometry is also the ground state of metal vacancies in other\ncarbides such as ZrC, HfC, and VC. The reconstructed metal vacancies are\ncharacterized by localized electron states due to the relatively short C-C\nbonds. The defect states lie just below the upper and lower valence bands. The\nexistence of reconstructed vacancy configurations is essential for\nunderstanding the mechanism of metal self-diffusion in transition-metal\ncarbides.",
        "positive": "A universal description of III-V/Si epitaxial growth processes: Here, we experimentally and theoretically clarify III-V/Si crystal growth\nprocesses. Atomically-resolved microscopy shows that mono-domain 3D islands are\nobserved at the early stages of AlSb, AlN and GaP epitaxy on Si, independently\nof misfit. It is also shown that complete III-V/Si wetting cannot be achieved\nin most III-V/Si systems. Surface/interface contributions to the free energy\nvariations are found to be prominent over strain relief processes. We finally\npropose a general and unified description of III-V/Si growth processes,\nincluding the description of antiphase boundaries formation."
    },
    {
        "anchor": "Spin-Hall magnetoresistance and spin Seebeck effect in spin-spiral and\n  paramagnetic phases of multiferroic CoCr2O4 films: We report on the spin-Hall magnetoresistance (SMR) and spin Seebeck effect\n(SSE) in multiferroic CoCr2O4 (CCO) spinel thin films with Pt contacts. We\nobserve a large enhancement of both signals below the spin-spiral (Ts = 28 K)\nand the spin lock-in transitions (T_{lock_in} = 14 K). The SMR and SSE response\nin the spin lock-in phase are one order of magnitude larger than those observed\nat the ferrimagnetic transition temperature (Tc = 94 K), which indicates that\nthe interaction between spins at the Pt|CCO interface is more efficient in the\nnon-collinear magnetic state below Ts and T_{lock-in}. At T > Tc, magnetic\nfield-induced SMR and SSE signals are observed, which can be explained by a\nhigh interface susceptibility. Our results show that the spin transport at the\nPt|CCO interface is sensitive to the magnetic phases but cannot be explained\nsolely by the bulk magnetization.",
        "positive": "Role of structural relaxations, chemical substitutions and polarization\n  fields on the potential line-up in [0001] wurtzite GaN/Al systems: First-principles full-potential linearized augmented plane wave (FLAPW)\ncalculations are performed to clarify the role of the interface geometry on\npiezoelectric fields and on potential line-ups at the [0001]-wurtzite and\n[111]-zincblende GaN/Al junctions. The electric fields (polarity and magnitude)\nare found to be strongly affected by atomic relaxations in the interface\nregion. A procedure is tested to evaluate the Schottky barrier in the presence\nof electric fields and used to show that their effect is quite small (a few\ntenths of an eV). These calculations assess the rectifying behaviour of the\nGaN/Al contact, giving very good agreement with experimental values for the\nbarrier. Stimulated by the complexity of the problem, we disentangle chemical\nand structural effects on the relevant properties (such as the potential\ndiscontinuity and electric fields) by studying auxiliary unrelaxed\nnitride/metal systems. Focusing on simple electronegativity arguments, we\noutline the leading mechanisms that result in the final values of the electric\nfields and Schottky barriers in these ideal interfaces. Finally, the\ntransitivity rule in the presence of two inequivalent junctions is proved to\ngive reliable results."
    },
    {
        "anchor": "On fundamental mechanisms in dye sensitized solar cells through the\n  behaviour of different mesoporous titanium dioxide films: Understanding mechanisms in DSSCs is fundamental for their improvement; this\nincludes the nanocrystalline semiconducting layer behaviour. Different\nmesoporous TiO2 layers are fabricated and analyzed for possible use in DSSC\nsolar cells. The preparations included the addition of P123 triblock copolymer\nas structuring agent to the synthesized anatase sol. This preparation was also\nmixed with Degussa P25 nanoparticles in one case and polystyrene latex in\nanother. Mesoporous mixed TiO2-SiO2 thin layers were also analyzed. The diverse\nmorphology and features are studied by microscopic techniques and by means of\nspectral quantum efficiency of a photoelectrochemical cell (PEC) that uses as\nphotoelectrode the unsensitized porous TiO\\_2 layer. Contact angle measurements\nare also performed. We have found that a very high specific area due to very\nsmall nanocrystals and small pores can hinder electrolyte penetration in the\npores formed by TiO\\_2 nanograins, affecting photoelectrodes efficiency.",
        "positive": "Co-development of significant elastic and reversible plastic deformation\n  in nanowires: When a material is subjected to an applied stress, the material will\nexperience recoverable elastic deformation followed by permanent plastic\ndeformation at the point when the applied stress exceeds the yield stress of\nthe material. Microscopically, the onset of the plasticity usually indicates\nthe activation of dislocation motion, which is considered to be the primary\nmechanism of plastic deformation. Once plastic deformation is initiated,\nfurther elastic deformation is negligible owing to the limited increase in the\nflow stress caused by work hardening. Here we present experimental evidence and\nquantitative analysis of simultaneous development of significant elastic\ndeformation and dislocation-based plastic deformation in single crystal GaAs\nnanowires (NWs) under bending deformation up to a total strain of ~ 6%. The\nobservation is in sharp contrast to the previous notions regarding the\ndeformation modes. Most of the plastic deformation recovers spontaneously when\nthe external stress is released, and therefore resembles an elastic deformation\nprocess."
    },
    {
        "anchor": "A high-throughput ab initio review of platinum-group alloy systems: We report a comprehensive study of the binary systems of the platinum group\nmetals with the transition metals, using high-throughput first-principles\ncalculations. These computations predict stability of new compounds in 38\nbinary systems where no compounds have been reported in the literature\nexperimentally, and a few dozen of as yet unreported compounds in additional\nsystems. Our calculations also identify stable structures at compound\ncompositions that have been previously reported without detailed structural\ndata and indicate that some experimentally reported compounds may actually be\nunstable at low temperatures. With these results we construct enhanced\nstructure maps for the binary alloys of platinum group metals. These are much\nmore complete, systematic and predictive than those based on empirical results\nalone.",
        "positive": "Correct and accurate polymorphic energy ordering of transition-metal\n  monoxides obtained from semilocal and onsite-hybrid exchange-correlation\n  approximations: The relative energetic stability of the structural phases of common\nantiferromagnetic transition-metal oxides (MnO, FeO, CoO, and NiO) within the\nsemilocal and hybrid density functionals are fraught with difficulties. In\nparticular, MnO is known to be the most difficult case for almost all common\nsemilocal and hybrid density approximations. Here, we show that the\nmeta-generalized gradient approximation (meta-GGA) constructed from the\ncuspless hydrogen model and Pauli kinetic energy density (MGGAC) can lead to\nthe correct ground state of MnO. The relative energy differences of zinc-blende\n(zb) and rock-salt (rs) structures as computed using MGGAC are found to be in\nnice agreement with those obtained from high-level correlation methods like the\nrandom phase approximation or quantum Monte Carlo techniques. Besides, we have\nalso applied the onsite hybrid functionals (closely related to DFT+U ) based on\nGGA and meta-GGA functionals, and it is shown that a relatively high amount of\nHartree-Fock exchange is necessary to obtain the correct ground-state\nstructure. Our present investigation suggests that the semilocal MGGAC and\nonsite hybrids, both being computationally cheap, as methods of choice for the\ncalculation of the relative stability of antiferromagnetic transition-metal\noxides having potential applications in solid-state physics and structural\nchemistry."
    },
    {
        "anchor": "The Efficiency Limit of CH3NH3PbI3 Perovskite Solar Cells: With the consideration of photon recycling effect, the efficiency limit of\nmethylammonium lead iodide (CH3NH3PbI3) perovskite solar cells is predicted by\na detailed balance model. To obtain convincing predictions, both AM 1.5\nspectrum of Sun and experimentally measured complex refractive index of\nperovskite material are employed in the detailed balance model. The roles of\nlight trapping and angular restriction in improving the maximal output power of\nthin-film perovskite solar cells are also clarified. The efficiency limit of\nperovskite cells (without the angular restriction) is about 31%, which\napproaches to Shockley-Queisser limit (33%) achievable by gallium arsenide\n(GaAs) cells. Moreover, the Shockley-Queisser limit could be reached with a 200\nnm-thick perovskite solar cell, through integrating a wavelength-dependent\nangular-restriction design with a textured light-trapping structure.\nAdditionally, the influence of the trap-assisted nonradiative recombination on\nthe device efficiency is investigated. The work is fundamentally important to\nhigh-performance perovskite photovoltaics.",
        "positive": "Machine learning predictions of superalloy microstructure: Gaussian process regression machine learning with a physically-informed\nkernel is used to model the phase compositions of nickel-base superalloys. The\nmodel delivers good predictions for laboratory and commercial superalloys, with\n$R^2>0.8$ for all but two components of each of the $\\gamma$ and $\\gamma'$\nphases, and $R^2=0.924$ ($\\mathrm{RMSE}=0.063$) for the $\\gamma'$ fraction. For\nfour benchmark SX-series alloys the methodology predicts the $\\gamma'$ phase\ncomposition with $\\mathrm{RMSE}=0.006$ and the fraction with\n$\\mathrm{RMSE}=0.020$, superior to the $0.007$ and $0.021$ respectively from\nCALPHAD. Furthermore, unlike CALPHAD Gaussian process regression quantifies the\nuncertainty in predictions, and can be retrained as new data becomes available."
    },
    {
        "anchor": "Effectiveness of nanoinclusions for reducing bipolar effects in\n  thermoelectric materials: Bipolar carrier transport is often a limiting factor in the thermoelectric\nefficiency of narrow bandgap materials (such as Bi2Te3 and PbTe) at high\ntemperatures due to the introduction of an additional term to the thermal\nconductivity and a reduction in the Seebeck coefficient. In this work, we\npresent a theoretical investigation into the ability of nanoinclusions to\nreduce the detrimental effect of bipolar transport. Using the quantum\nmechanical non equilibrium Greens function (NEGF) transport formalism, we\nsimulate electronic transport through two-dimensional systems containing\ndensely packed nanoinclusions, separated by distances similar to the electron\nmean free path. Specifically, considering an n type material, where the bipolar\neffect comes from the valence band, we insert nanoinclusions that impose\npotential barriers only for the minority holes. We then extract the materials\nelectrical conductivity, Seebeck coefficient, and electronic thermal\nconductivity including its bipolar contribution. We show that nanoinclusions\ncan indeed have some success in reducing the minority carrier transport and the\nbipolar effect on both the electronic thermal conductivity and the Seebeck\ncoefficient. The benefits from reducing the bipolar conductivity are larger the\nmore conductive the minority band is to begin with (larger hole mean free path\nin particular), as expected. Interestingly, however, the benefits on the\nSeebeck coefficient and the power factor are even more pronounced not only when\nthe minority mean free path is large, but when it is larger compared to the\nmajority conduction band mean free path. Finally, we extract an overall\nestimate for the benefits that nanoinclusions can have on the ZT figure of\nmerit.",
        "positive": "Non-Arrhenius relaxation of the Heisenberg model with dipolar and\n  anisotropic interactions: The dynamical properties of a 2D Heisenberg model with dipolar interactions\nand perpendicular anisotropy are studied using Monte Carlo simulations in two\ndifferent ordered regions of the equilibrium phase diagram. We find a\ntemperature defining a dynamical transition below which the relaxation suddenly\nslows down and the system aparts from the typical Arrhenius relaxation to a\nVogel-Fulcher-Tamann law. This anomalous behavior is observed in the scaling of\nthe magnetic relaxation and may eventually lead to a freezing of the system.\nThrough the analysis of the domain structures we explain this behavior in terms\nof the domains dynamics. Moreover, we calculate the energy barriers\ndistribution obtained from the data of the magnetic viscosity. Its shape\nsupports our comprehension of both, the Vogel-Fulcher-Tamann dynamical slowing\ndown and the freezing mechanism."
    },
    {
        "anchor": "p-type doping in CVD grown MoS2 using Nb: We report on the first demonstration of p-type doping in large area few-layer\nfilms of (0001)-oriented chemical vapor deposited (CVD) MoS2. Niobium was found\nto act as an efficient acceptor up to relatively high density in MoS2 films.\nFor a hole density of 4 x 1020 cm-3 Hall mobility of 8.5 cm2V-1s-1 was\ndetermined, which matches well with the theoretically expected values. XRD and\nRaman characterization indicate that the film had good out-of-plane crystalline\nquality. Absorption measurements showed that the doped sample had similar\ncharacteristics to high-quality undoped samples, with a clear absorption edge\nat 1.8 eV. This demonstration of p-doping in large area epitaxial MoS2 could\nhelp in realizing a wide variety of electrical and opto-electronic devices\nbased on layered metal dichalcogenides.",
        "positive": "Topological phonons in an inhomogeneously strained silicon-4: Large spin\n  dependent thermoelectric response and thermal spin transfer torque due to\n  topological electronic magnetism of phonons: The superposition of flexoelectronic doping and topological phonons give rise\nto topological electronic magnetism of phonon in an inhomogeneously strained Si\nin the bilayer structure with metal. In case of ferromagnetic metal and Si\nbilayer structure, the flexoelectronic doping will also give rise to larger\nspin current, which will lead to large spin to charge conversion due to\ntopological electronic magnetism of phonon. By applying a temperature\ndifference to ferromagnetic metal/Si bilayer structure under an applied strain\ngradient, a large thermoelectric response can be generated. In this\nexperimental study, we report a large spin dependent thermoelectric response at\nNi80Fe20/Si bilayer structure. The spin dependent response is found to be an\norder of magnitude larger than that in Pt thin films and similar to topological\ninsulators surface states in spite of negligible intrinsic spin-orbit coupling\nof Si. This large response is attributed to the flexoelectronic doping and\ntopological electronic magnetism of phonons, which was uncovered using\ntopological Nernst effect measurement. This alternative and novel approach of\nusing inhomogeneous strain engineering to address both spin current density and\nspin to charge conversion can open a new window to the realization of\nspintronics and spin-caloritronics devices using metal and doped-semiconductor\nlayered materials."
    },
    {
        "anchor": "Geometrical theory of the shift current in presence of disorder and\n  interaction: The electric field of light induces--in a non centrosymmetric insulator--a dc\ncurrent, quadratic in the field magnitude, and called \"shift current\". When\naddressed from a many-electron viewpoint, the shift current has a simple\nexplanation and a simple formulation as well, deeply rooted in quantum\ngeometry. The basic formula is then specialized to the independent-electron\ncase, first for a disordered system in a supercell formulation, and then for a\ncrystalline system. In the latter case the known shift-current formula is\nretrieved in a very transparent way.",
        "positive": "Cubine, a superconducting 2-dimensional copper-bismuth nano sheet: We report on the discovery of a 2-dimensional copper-bismuth nano sheet from\n\\textit{ab initio} calculations, which we call cubine. According to our\npredictions, single layers of cubine can be isolated from the recently reported\nhigh-pressure CuBi bulk material (metastable at ambient conditions) at an\nenergetic cost of merely $\\approx 20$~meV/\\AA$^2$, comparable to separating\nsingle layers of graphene from graphite. Our calculations suggest that cubine\nhas remarkable electronic and electrochemical properties: It is a\nsuperconductor with a moderate electron-phonon coupling $\\lambda=0.5$, leading\nto a $T_c$ of $\\approx1$~K, and can be readily intercalated with lithium with a\nhigh diffusibility, rendering it a promising candidate material as an anode in\nlithium-ion batteries."
    },
    {
        "anchor": "A non incremental variational principle for brittle fracture: The aim of the paper is to propose a paradigm shift for the variational\napproach of brittle fracture. Both dynamics and the limit case of statics are\ntreated in a same framework. By contrast with the usual incremental approach,\nwe use a space-time principle covering the whole loading and crack evolution.\nThe emphasis is given on the modelling of the crack extension by the internal\nvariable formalism and a dissipation potential as in plasticity, rather than\nGriffith's original approach based on the surface area. The new formulation\nappears to be more fruitful for generalization than the standard theory.",
        "positive": "Electron-Phonon Dynamics in an Ensemble of Nearly Isolated Nanoparticles: We investigate the electron population dynamics in an ensemble of nearly\nisolated insulating nanoparticles, each nanoparticle modeled as an electronic\ntwo-level system coupled to a single vibrational mode. We find that at short\ntimes the ensemble-averaged excited-state population oscillates but has a\ndecaying envelope. At long times, the oscillations become purely sinusoidal\nabout a ``plateau'' population, with a frequency determined by the\nelectron-phonon interaction strength, and with an envelope that decays\nalgebraically as t^-{1/2} We use this theory to predict electron-phonon\ndynamics in an ensemble of Y_2 O_3 nanoparticles."
    },
    {
        "anchor": "Wavepacket representation of leads for efficient simulations of\n  time-dependent electronic transport: We present theoretical foundations and numerical demonstration of an\nefficient method for performing time-dependent many-electron simulations for\nelectronic transport. The method employs the concept of stroboscopic wavepacket\nbasis for the description of electrons' dynamics in the semi-infinite leads.The\nrest of the system can be treated using common propagation schemes for finite\nelectronic systems. We use the implementation of our method to study the\ntime-dependent current response in armchair graphene nano-ribbons (AGNR) with\nsizes up to 800 atoms described within tight-binding approximation. The\ncharacter of the time-dependent current is studied for different magnitudes of\nthe bias voltage, variable width and length of AGNRs, different positions of\nthe current measurement, and for full and reduced coupling of the AGNRs to the\nelectrodes.",
        "positive": "Investigating charge trapping in ferroelectric thin films through\n  transient measurements: A measurement technique is presented to quantify the polarization loss in\nferroelectric thin films as a function of delay time during the first 100s\nafter switching. This technique can be used to investigate charge trapping in\nferroelectric thin films by analyzing the magnitude and rate of polarization\nloss. Exemplary measurements have been performed on Hf0.5Zr0.5O2 (HZO) and\nHZO/Al2O3 films, as a function of pulse width and temperature. It is found that\nthe competing effects of the depolarization field, internal bias field and\ncharge trapping lead to a characteristic Gaussian dependence of the rate of\npolarization loss on the delay time. From this, a charge trapping and screening\nmodel could be identified which describes the dynamics of polarization loss on\nshort timescales."
    },
    {
        "anchor": "Surface lattice Green's functions for high-entropy alloys: We study the surface elastic response of pure Ni, the random alloy FeNiCr and\nan average FeNiCr alloy in terms of the surface lattice Green's function. We\npropose a scheme for computing per-site Green's function and study their\nper-site variations. The average FeNiCr alloy accurately reproduces the mean\nGreen's function of the full random alloy. Variation around this mean is\nlargest near the edge of the surface Brillouin-zone and decays as $q^{-2}$ with\nwavevector $q$ towards the $\\Gamma$-point. We also present expressions for the\ncontinuum surface Green's function of anisotropic solids of finite and infinite\nthickness and show that the atomistic Green's function approaches continuum\nnear the $\\Gamma$-point. Our results are a first step towards efficient contact\ncalculations and Peierls-Nabarro type models for dislocations in high-entropy\nalloys.",
        "positive": "Room-temperature magnetoelectric effect in lead-free multiferroic\n  $(1-x)$ Ba$_{0.95}$Ca$_{0.05}$Ti$_{0.89}$Sn$_{0.11}$O$_3$-$(x)$CoFe$_2$O$_4$\n  particulate composites: Multiferroic particulate composites $(1-x)$\nBa$_{0.95}$Ca$_{0.05}$Ti$_{0.89}$Sn$_{0.11}$O$_3$-$(x)$CoFe$_2$O$_4$ with ($x$\n= 0.1, 0.2, 0.3, 0.4 and 0.5) have been prepared by mechanical mixing of the\ncalcined and milled individual ferroic phases. X-ray diffraction and Raman\nspectroscopy analysis confirmed the formation of both perovskite\nBa$_{0.95}$Ca$_{0.05}$Ti$_{0.89}$Sn$_{0.11}$O$_3$ (BCTSn) and spinel\nCoFe$_2$O$_4$ (CFO) phases without the presence of additional phases. The\nmorphological properties of the composites were provided by using Field\nEmission Scanning Electron Microscopy. The BCTSn-CFO composites exhibit\nmultiferroic behavior at room temperature, as evidenced by ferroelectric and\nferromagnetic hysteresis loops. The magnetoelectric (ME) coupling was measured\nunder a magnetic field up to 10 kOe and the maximum ME response found to be 0.1\nmV /cm/ Oe for the composition 0.7 BCTSn-0.3 CFO exhibiting a high degree of\npseudo-cubicity and large density."
    },
    {
        "anchor": "Uncovering structure-property relationships of materials by subgroup\n  discovery: Subgroup discovery (SGD) is presented here as a data-mining approach to help\nfind interpretable local patterns, correlations, and descriptors of a target\nproperty in materials-science data. Specifically, we will be concerned with\ndata generated by density-functional theory calculations. At first, we\ndemonstrate that SGD can identify physically meaningful models that classify\nthe crystal structures of 82 octet binary semiconductors as either rocksalt or\nzincblende. SGD identifies an interpretable two-dimensional model derived from\nonly the atomic radii of valence s and p orbitals that properly classifies the\ncrystal structures for 79 of the 82 octet binary semiconductors. The SGD\nframework is subsequently applied to 24 400 configurations of neutral gas-phase\ngold clusters with 5 to 14 atoms to discern general patterns between\ngeometrical and physicochemical properties. For example, SGD helps find that\nvan der Waals interactions within gold clusters are linearly correlated with\ntheir radius of gyration and are weaker for planar clusters than for nonplanar\nclusters. Also, a descriptor that predicts a local linear correlation between\nthe chemical hardness and the cluster isomer stability is found for the\neven-sized gold clusters.",
        "positive": "Novel Dirac Electron in Single-Component Molecular Conductor\n  [Pd(dddt)$_2$]: Dirac electrons in a single-component molecular conductor [Pd(dddt)$_2$]\nunder pressure have been examined using a tight-binding model which consists of\nHOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular\nOrbital) functions in four molecules per unit cell. The Dirac cone between the\nconduction and valence bands comes from the property that HOMO has ungerade\nsymmetry and LUMO has gerade symmetry. The Dirac point forms a loop in the\nthree-dimensional Brillouin zone, which is symmetric with respect to the plane\nof $k_y$ = 0 where $k_y$ is the intralayer momentum along the molecular\nstacking direction, i.e., with the largest (HOMO-HOMO, LUMO-LUMO) transfer\nenergy. The parity at TRIM (time reversal invariant momentum) is calculated\nusing the inversion symmetry around the lattice point of the crystal. It is\nshown that such an exotic Dirac electron is understood from the parity of the\nwave function at the TRIM and also from an effective Hamiltonian."
    },
    {
        "anchor": "Tight-binding molecular-dynamics studies of defects and disorder in\n  covalently-bonded materials: Tight-binding (TB) molecular dynamics (MD) has emerged as a powerful method\nfor investigating the atomic-scale structure of materials --- in particular the\ninterplay between structural and electronic properties --- bridging the gap\nbetween empirical methods which, while fast and efficient, lack\ntransferability, and ab initio approaches which, because of excessive\ncomputational workload, suffer from limitations in size and run times. In this\nshort review article, we examine several recent applications of TBMD in the\narea of defects in covalently-bonded semiconductors and the amorphous phases of\nthese materials.",
        "positive": "Imperfectly coordinated water molecules pave the way for homogeneous ice\n  nucleation: Water freezing is ubiquitous on Earth, affecting many areas from biology to\nclimate science and aviation technology. Probing the atomic structure in the\nhomogeneous ice nucleation process from scratch is of great value but still\nexperimentally unachievable. Theoretical simulations have found that ice\noriginates from the low-mobile region with increasing abundance and persistence\nof tetrahedrally coordinated water molecules. However, a detailed microscopic\npicture of how the disordered hydrogen-bond network rearranges itself into an\nordered network is still unclear. In this work, we use a deep neural network\n(DNN) model to \"learn\" the interatomic potential energy from quantum mechanical\ndata, thereby allowing for large-scale and long molecular dynamics (MD)\nsimulations with ab initio accuracy. The nucleation mechanism and dynamics at\natomic resolution, represented by a total of 36 $\\mu$s-long MD trajectories,\nare deeply affected by the structural and dynamical heterogeneity in\nsupercooled water. We find that imperfectly coordinated (IC) water molecules\nwith high mobility pave the way for hydrogen-bond network rearrangement,\nleading to the growth or shrinkage of the ice nucleus. The hydrogen-bond\nnetwork formed by perfectly coordinated (PC) molecules stabilizes the nucleus,\nthus preventing it from vanishing and growing. Consequently, ice is born\nthrough competition and cooperation between IC and PC molecules. We anticipate\nthat our picture of the microscopic mechanism of ice nucleation will provide\nnew insights into many properties of water and other relevant materials."
    },
    {
        "anchor": "Anomalous optical and electronic properties of dense sodium: Based on ab initio density-functional-theory using generalized gradient\napproximation, we systematically study the optical and electronic properties of\nthe insulating dense sodium phase (Na-hp4) reported recently [Ma \\textit{et\nal.}, Nature \\textbf{458}, 182 (2009)]. The structure is found optically\nanisotropic and transparent to visible light, which can be well interpreted\nusing its electronic band structure and angular moment decomposed density of\nstates. Through the bader analysis of Na-hp4 at different pressures, we\nconclude that ionicity exists in the structure and becomes stronger with\nincreasing pressure. In addition, the absorption spectra in the energy range\nfrom 1.4 to 2.4 eV are compared with recent experimental results and found good\nagreement. It is found that the deep-lying valence electrons participate in the\ninterband transition.",
        "positive": "Iron-rich Fe-O compounds with closest-packed layers at core pressures: Oxygen solubility in solid iron is extremely low, even at high pressures and\ntemperatures. Thus far, no Fe-O compounds between Fe and FeO endmembers have\nbeen reported experimentally. We observed chemical reactions of Fe with FeO or\nFe$_2$O$_3$ $in\\ situ$ x-ray diffraction experiments at 220-260 GPa and\n3,000-3,500 K. The refined diffraction patterns are consistent with a series of\nFe$_n$O (n $>$ 1) compounds (e.g., Fe$_{25}$O$_{13}$ and Fe$_{28}$O$_{14}$)\nidentified using the adaptive genetic algorithm. Like $\\epsilon$-Fe in the\nhexagonal close-packed (hcp) structure, the structures of Fe$_n$O compounds\nconsist of oxygen-only close-packed monolayers distributed between iron-only\nlayers. $Ab\\ initio$ calculations show systematic electronic properties of\nthese compounds that have ramifications for the physical properties of Earth's\ninner core."
    },
    {
        "anchor": "Giant negative thermal expansion covering room temperature in\n  nanocrystalline GaNxMn3: Materials with negative thermal expansion (NTE), which contract upon heating,\nare of great interest both technically and fundamentally. Here, we report giant\nNTE covering room temperature in mechanically milled antiperovksite GaNxMn3\ncompounds. The micrograin GaNxMn3 exhibits a large volume contraction at the\nantiferromagnetic (AFM) to paramagnetic (PM) (AFM-PM) transition within a\ntemperature window ({\\Delta}T) of only a few kelvins. The grain size reduces to\n~ 30 nm after slight milling, while {\\Delta}T is broadened to 50K. The\ncorresponding coefficient of linear thermal expansion ({\\alpha}) reaches ~ -70\nppm/K, which is almost two times larger than those obtained in chemically doped\nantiperovskite compounds. Further reducing grain size to ~ 10 nm, {\\Delta}T\nexceeds 100 K and {\\alpha} remains as large as -30 ppm/K (-21 ppm/K) for x =\n1.0 (x = 0.9). Excess atomic displacements together with the reduced structural\ncoherence, revealed by high-energy X-ray pair distribution functions, are\nsuggested to delay the AFM-PM transition. By controlling the grain size via\nmechanically alloying or grinding, giant NTE may also be achievable in other\nmaterials with large lattice contraction due to electronic or magnetic phase\ntransitions.",
        "positive": "Bulk and film synthesis pathways to ternary magnesium tungsten nitrides: Bulk solid state synthesis of nitride materials usually leads to\nthermodynamically stable, cation-ordered crystal structures, whereas thin film\nsynthesis tends to favor disordered, metastable phases. This dichotomy is\ninconvenient both for basic materials discovery, where non-equilibrium thin\nfilm synthesis methods can be useful to overcome reaction kinetic barriers, and\nfor practical technology applications where stable ground state structures are\nsometimes required. Here, we explore the uncharted Mg-W-N chemical phase space,\nusing rapid thermal annealing to reconcile the differences between thin film\nand bulk powder syntheses. Combinatorial co-sputtering synthesis from Mg and W\ntargets in a N$_2$ environment yielded cation-disordered Mg-W-N phases in the\nrocksalt (0.1< Mg/(Mg+W) <0.9), and hexagonal boron nitride (0.7< Mg/(Mg+W)\n<0.9) structure types. In contrast, bulk synthesis produced a cation-ordered\npolymorph of MgWN$_2$ that consists of alternating layers of rocksalt-like\n[MgN$_6$] octahedra and nickeline-like [WN$_6$] trigonal prisms (denoted\n\"rocksaline\"). Thermodynamic calculations corroborate these observations,\nshowing rocksaline MgWN$_2$ is stable while other polymorphs are metastable. We\nalso show that rapid thermal annealing can convert disordered rocksalt films to\nthis cation-ordered polymorph near the MgWN$_2$ stoichiometry. Electronic\nstructure calculations suggest that this rocksalt-to-rocksaline structural\ntransformation should also drive a metallic-to-semiconductor transformation. In\naddition to revealing three new phases (rocksalt MgWN$_2$ and Mg$_3$WN$_4$,\nhexagonal boron nitride Mg$_3$WN$_4$, and rocksaline MgWN$_2$), these findings\nhighlight how rapid thermal annealing can control polymorphic transformations,\nadding a new strategy for exploration of thermodynamic stability in uncharted\nphase spaces."
    },
    {
        "anchor": "The Landau-Lifshitz-Bloch equation for ferrimagnetic materials: We derive the Landau-Lifshitz-Bloch (LLB) equation for a two-component\nmagnetic system valid up to the Curie temperature. As an example, we consider\ndisordered GdFeCo ferrimagnet where the ultrafast optically induced\nmagnetization switching under the action of heat alone has been recently\nreported. The two-component LLB equation contains the longitudinal relaxation\nterms responding to the exchange fields from the proper and the neighboring\nsublattices. We show that the sign of the longitudinal relaxation rate at high\ntemperatures can change depending on the dynamical magnetization value and a\ndynamical polarisation of one material by another can occur. We discuss the\ndifferences between the LLB and the Baryakhtar equation, recently used to\nexplain the ultrafast switching in ferrimagnets. The two-component LLB equation\nforms basis for the largescale micromagnetic modeling of nanostructures at high\ntemperatures and ultrashort timescales.",
        "positive": "Large-scale surface reconstruction energetics of Pt(100) and Au(100) by\n  all-electron DFT: The low-index surfaces of Au and Pt all tend to reconstruct, a fact that is\nof key importance in many nanostructure, catalytic, and electrochemical\napplications. Remarkably, some significant questions regarding their structural\nenergies remain even today, in particular for the large-scale quasihexagonal\nreconstructed (100) surfaces: Rather dissimilar reconstruction energies for Au\nand Pt in available experiments, and experiment and theory do not match for Pt.\nWe here show by all-electron density-functional theory that only large enough\n\"(5 x N)\" approximant supercells capture the qualitative reconstruction energy\ntrend between Au(100) and Pt(100), in contrast to what is often done in the\ntheoretical literature. Their magnitudes are then in fact similar, and closer\nto the measured value for Pt(100); our calculations achieve excellent agreement\nwith known geometric characteristics and provide direct evidence for the\nelectronic reconstruction driving force."
    },
    {
        "anchor": "A Quantum-Chemical Bonding Database for Solid-State Materials: An in-depth insight into the chemistry and nature of the individual chemical\nbonds is essential for understanding materials. Bonding analysis is thus\nexpected to provide important features for large-scale data analysis and\nmachine learning of material properties. Such chemical bonding information can\nbe computed using the LOBSTER software package, which post-processes modern\ndensity functional theory data by projecting the plane wave-based wave\nfunctions onto a local, atomic orbital basis. With the help of a fully\nautomatic workflow, the VASP and LOBSTER software packages are used to generate\nthe data. We then perform bonding analyses on 1520 compounds (insulators and\nsemiconductors) and provide the results as a database. The database structure\nof the bonding analysis database, which allows easy data retrieval, is also\nexplained. The projected densities of states and bonding indicators are\nbenchmarked on standard density-functional theory computations and available\nheuristics, respectively. Lastly, we illustrate the predictive power of bonding\ndescriptors by constructing a machine-learning model for phononic properties,\nwhich shows an increase in prediction accuracies by 27 % (mean absolute errors)\ncompared to a benchmark model differing only by not relying on any\nquantum-chemical bonding features.",
        "positive": "Magnetic structure and phase diagram in a spin-chain system:\n  Ca$_3$Co$_2$O$_6$: The low-temperature structure of the frustrated spin-chain compound\nCa$_3$Co$_2$O$_6$ is determined by the ground state of the 2D Ising model on\nthe triangular lattice. At high-temperatures it transforms to the honeycomb\nmagnetic structure. It is shown that the crossover between the two magnetic\nstructures at 12 K arises from the entropy accumulated in the disordered\nchains. This interpretation is in an agreement with the experimental data.\nGeneral rules for for the phase diagram of frustrated Ising chain compounds are\nformulated."
    },
    {
        "anchor": "Ferroelectric Properties of Monoclinic Pb(Mg1/3Nb2/3)O3 - PbTiO3\n  Crystals: A monoclinic phase was recently discovered near the morphotropic phase\nboundary in several high-performance piezoelectric perovskite solid solutions,\nbut its properties have not been reported. In this paper the dielectric, piezo-\nand ferroelectric properties of the monoclinic Pm phase in the\n(1-x)Pb(Mg1/3Nb2/3)O3 -xPbTiO3 perovskite system are studied. In a\n(001)-oriented crystal of composition x=0.33, ferroelectric hysteresis loops\nwith remanent polarization of 23 uC/cm^2 are displayed. In poled monoclinic\ncrystals, under unipolar drive up to 10 kV/cm, the domain walls remain\nunchanged, the polarization and longitudinal strain change almost linearly, but\nthe piezoelectric response (d33=9x10^(-10) C/N) is much weaker than in the\nrhombohedral phase of close composition. The relative dielectric permittivity\nof the Pm phase is also smaller (with a small-signal value of ~ 2500), but the\npiezoelectric constant (g33 = 3 x10^(-2) m^2/C) and the electromechanical\ncoupling factor (kt = 0.60) are practically the same as in the rhombohedral\nphase. The properties of the various phases in the range of the morphotropic\nphase boundary are related to the different rotation paths of the polarization\nvector induced by the external drive.",
        "positive": "Low-temperature thermal transport and thermopower of monolayer\n  transition metal dichalcogenide semiconductors: We study the low temperature thermal conductivity of single-layer transition\nmetal dichalcogenides. In the low temperature regime where heat is carried\nprimarily through transport of electrons, thermal conductivity is linked to\nelectrical conductivity through the Wiedemann-Franz law. Using a \\textit{k.p}\nHamiltonian that describes the $ K $ and $ K^{'} $ valley edges, we compute the\nzero-frequency electric (Drude) conductivity using the Kubo formula to obtain a\nnumerical estimate for the thermal conductivity. The impurity scattering\ndetermined transit time of electrons which enters the Drude expression is\nevaluated within the self-consistent Born approximation. The analytic\nexpressions derived show that low temperature thermal conductivity 1) is\ndetermined by the band gap at the valley edges in monolayer TMDCs and 2) in\npresence of disorder which can give rise to the variable range hopping regime,\nthere is a distinct reduction. Additionally, we compute the Mott thermopower\nand demonstrate that under a high frequency light beam that sets up a Floquet\nHamiltonian, a valley-resolved thermopower can be obtained. A closing summary\nreviews the implications of results followed by a brief discussion on\napplicability of the Wiedemann-Franz law and its breakdown in context of the\npresented calculations."
    },
    {
        "anchor": "Large magnetic anisotropy predicted for rare-earth free Fe16-xCoxN2\n  alloys: Structures and magnetic properties of Fe16-xCoxN2 are studied using adaptive\ngenetic algorithm and first-principles calculations. We show that substituting\nFe by Co in Fe16N2 with Co/Fe ratio smaller than 1 can greatly improve the\nmagnetic anisotropy of the material. The magnetocrystalline anisotropy energy\nfrom first-principles calculations reaches 3.18 MJ/m3 (245.6 {\\mu}eV per metal\natom) for Fe12Co4N2, much larger than that of Fe16N2 and is one of the largest\namong the reported rare-earth free magnets. From our systematic crystal\nstructure searches, we show that there is a structure transition from\ntetragonal Fe16N2 to cubic Co16N2 in Fe16-xCoxN2 as the Co concentration\nincreases, which can be well explained by electron counting analysis. Different\nmagnetic properties between the Fe-rich (x < 8) and Co-rich (x > 8) Fe16-xCoxN2\nis closely related to the structural transition.",
        "positive": "The Effect of Strained Bonds on the Electronic Structure of Amorphous\n  Silicon: Several amorphous silicon structures were generated using a classical\nmolecular dynamics (MD) protocol of melting and quenching with different\nquenching rates. An analysis of the calculated electronic properties of these\nstructures revealed that the midgap state density of a-Si which is of interest\nfor solar cell and thin film transistor applications can be correlated to bond\nangle standard deviation. We also found that this parameter can strongly\ndetermine the excess energy of a-Si, which is an important criteria in\ntheoretically generating realistic atomic structures of a-Si."
    },
    {
        "anchor": "Simulation and optimisation of terahertz emission from InGaAs and InP\n  photoconductive switches: We simulate the terahertz emission from laterally-biased InGaAs and InP using\na three-dimensional carrier dynamics model in order to optimise the\nsemiconductor material. Incident pump-pulse parameters of current Ti:Sapphire\nand Er:fibre lasers are chosen, and the simulation models the semiconductor's\nbandstructure using parabolic Gamma, L and X valleys, and heavy holes. The\nemitted terahertz radiation is propagated within the semiconductor and into\nfree space using a model based on the Drude-Lorentz dielectric function. As the\nInGaAs alloy approaches InAs an increase in the emitted power is observed, and\nthis is attributed to a greater electron mobility. Additionally,\nlow-temperature grown and ion-implanted InGaAs are modelled using a finite\ncarrier trapping time. At sub-picosecond trapping times the terahertz bandwidth\nis found to increase significantly at the cost of a reduced emission power.",
        "positive": "First-principles study of band offsets in ferromagnetic semiconductor\n  heterojunctions: We report valence and conduction band alignments and offsets for\nheterojunctions between CdCr2Se4, an n-type ferromagnetic semiconductor, and\nthe non-magnetic materials Si and GaAs, evaluated using density functional\ntheory. We explore numerically the impact of different interface features on\nthe type of band alignment and the magnitude of the offsets. For example, we\nfind it is energetically favorable to deplete Cr atoms from the layers at the\ninterface; this also leads to band alignments smaller in magnitude compared to\nthose obtained for Cr-rich interfaces and ideal for electrical spin-injection\ninto either Si or Ga-terminated GaAs substrates."
    },
    {
        "anchor": "Response properties of III-V dilute magnetic semiconductors: interplay\n  of disorder, dynamical electron-electron interactions and band-structure\n  effects: A theory of the electronic response in spin and charge disordered media is\ndeveloped with the particular aim to describe III-V dilute magnetic\nsemiconductors like GaMnAs. The theory combines a detailed k.p description of\nthe valence band, in which the itinerant carriers are assumed to reside, with\nfirst-principles calculations of disorder contributions using an\nequation-of-motion approach for the current response function. A fully dynamic\ntreatment of electron-electron interaction is achieved by means of\ntime-dependent density functional theory. It is found that collective\nexcitations within the valence band significantly increase the carrier\nrelaxation rate by providing effective channels for momentum relaxation. This\nmodification of the relaxation rate, however, only has a minor impact on the\ninfrared optical conductivity in GaMnAs, which is mostly determined by the\ndetails of the valence band structure and found to be in agreement with\nexperiment.",
        "positive": "Beyond Wavelets: Exactness theorems and algorithms for physical\n  calculations: This paper develops the use of wavelets as a basis set for the solution of\nphysical problems exhibiting behavior over wide-ranges in length scale. In a\nsimple diagrammatic language, this article reviews both the mathematical\nunderpinnings of wavelet theory and the algorithms behind the fast wavelet\ntransform. This article underscores the fact that traditional wavelet bases are\nfundamentally ill-suited for physical calculations and shows how to go beyond\nthese limitations by the introduction of the new concept of semicardinality,\nwhich leads to the profound, new result that basic physical couplings may be\ncomputed {\\em without approximatation} from very sparse information, thereby\novercoming the limitations of traditional wavelet bases in the treatment of\nphysical problems. The paper then explores the convergence rate of conjugate\ngradient solution of the Poisson equation in both semicardinal and lifted\nwavelet bases and shows the first solution of the Kohn-Sham equations using a\nnovel variational principle."
    },
    {
        "anchor": "Electric control of spin injection into a ferroelectric semiconductor: Electric-field control of spin-dependent properties has become one of the\nmost attractive phenomena in modern materials research due the promise of new\ndevice functionalities. One of the paradigms in this approach is to\nelectrically toggle the spin polarization of carriers injected into a\nsemiconductor using ferroelectric polarization as a control parameter. Using\nfirst-principles density functional calculations, we explore the effect of\nferroelectric polarization of electron-doped BaTiO3 (n-BaTiO3) on the\nspin-polarized transmission across the SrRuO3/n-BaTiO3 (001) interface. Our\nstudy reveals that the interface transmission is negatively spin-polarized and\nthat ferroelectric polarization reversal leads to a change in the transport\nspin polarization from -65% to -98%. We show that this effect stems from the\nlarge difference in Fermi wave vectors between up- and down-spins in\nferromagnetic SrRuO3 and a change in the transport regime driven by\nferroelectric polarization switching. The predicted sizeable change in the spin\npolarization provides a non-volatile mechanism to electrically control spin\ninjection in semiconductor-based spintronics devices.",
        "positive": "Stress orientation of second-phase in alloys: Hydrides in zirconium\n  alloys: A model for precipitation of the plate-shaped second-phase under applied\nstress is presented. The precipitates in the matrix-precipitate system are\nrepresented by their local volume fraction and an orientation parameter that\ndefines the alignment of a precipitate platelet in a given direction. Kinetic\nequations, based on diffusion theory and classical nucleation theory, are used\nto describe the time evolution of these two parameters. The model is used to\ndescribe the stress orientation of hydrides in Zr-alloys in light of\nexperiments."
    },
    {
        "anchor": "Magnetic nanocomposites at microwave frequencies: Most conventional magnetic materials used in the electronic devices are\nferrites, which are composed of micrometer-size grains. But ferrites have small\nsaturation magnetization, therefore the performance at GHz frequencies is\nrather poor. That is why functionalized nanocomposites comprising magnetic\nnanoparticles (e.g. Fe, Co) with dimensions ranging from a few nm to 100 nm,\nand embedded in dielectric matrices (e.g. silicon oxide, aluminium oxide) have\na significant potential for the electronics industry. When the size of the\nnanoparticles is smaller than the critical size for multidomain formation,\nthese nanocomposites can be regarded as an ensemble of particles in\nsingle-domain states and the losses (due for example to eddy currents) are\nexpected to be relatively small. Here we review the theory of magnetism in such\nmaterials, and we present a novel measurement method used for the\ncharacterization of the electromagnetic properties of composites with\nnanomagnetic insertions. We also present a few experimental results obtained on\ncomposites consisting of iron nanoparticles in a dielectric matrix.",
        "positive": "Ab initio study on the effects of transition metal doping of Mg2NiH4: Mg2NiH4 is a promising hydrogen storage material with fast (de)hydrogenation\nkinetics. Its hydrogen desorption enthalpy, however, is too large for practical\napplications. In this paper we study the effects of transition metal doping by\nfirst-principles density functional theory calculations. We show that the\nhydrogen desorption enthalpy can be reduced by ~0.1 eV/H2 if one in eight Ni\natoms is replaced by Cu or Fe. Replacing Ni by Co atoms, however, increases the\nhydrogen desorption enthalpy. We study the thermodynamic stability of the\ndopants in the hydrogenated and dehydrogenated phases. Doping with Co or Cu\nleads to marginally stable compounds, whereas doping with Fe leads to an\nunstable compound. The optical response of Mg2NiH4 is also substantially\naffected by doping. The optical gap in Mg2NiH4 is ~1.7 eV. Doping with Co, Fe\nor Cu leads to impurity bands that reduce the optical gap by up to 0.5 eV."
    },
    {
        "anchor": "Topotactic phase transformation of the brownmillerite SrCoO2.5 to the\n  perovskite SrCoO3-\u03b4: Oxygen stoichiometry is one of the most important elements in determining the\nphysical properties of transition metal oxides (TMOs). A small fractional\nchange in the oxygen content, resulting in the variation of valence state of\nthe transition metal, can drastically modify the materials functionalities. In\nparticular, TMOs with mixed valences have attracted attention for many energy\napplications. Previous studies also showed that the ability to control the\nnumber of d-band electron populations and detailed spin configurations is\ncritical for improved catalytic performance of TMOs. In this context,\nSrCoO$_{x}$ (2.5 < x < 3.0) is an ideal class of materials due to the existence\nof two structurally distinct topotatic phases, i.e. the brownmillerite\nSrCoO$_{2.5}$(BM-SCO) and the perovskite SrCoO$_{3}$. Especially, BM-SCO has\natomically-ordered one-dimensional vacancy channels, which can accommodate\nadditional oxygen. Moreover, SrCoO$_{x}$ exhibits a wide spectrum of physical\nproperties depending on the oxygen stoichiometry. Since SrCoOx has only a\nsingle knob to control the Co valence state without cation doping, it is an\nattractive material for studying the valence state dependent physical\nproperties. However, so far, the growth of high quality single crystalline\nmaterials has not been much studied due to difficulty in controlling the right\noxidation state. In this work, we report on the epitaxial growth of BM-SCO\nsingle crystalline films on SrTiO3 by pulsed laser epitaxy. In order to examine\nthe topotactic phase transformation to the perovskite SrCoO$_{3-\\delta}$, some\nof samples were subsequently in-situ annealed at various oxygen pressure\nP(O$_{2}$). We found that post-annealing in high P(O$_{2}$) (> several hundreds\nof Torr) could fill some of oxygen vacancies accompanying systematic evolution\nin electronic, magnetic, and thermoelectric properties.",
        "positive": "Fe3O4(110)-(1x3) Revisited: Periodic (111) Nano-Facets: The structure of the Fe3O4(110)-(1x3) surface was studied with scanning\ntunneling microscopy (STM), low-energy electron diffraction (LEED), and\nreflection high energy electron diffraction (RHEED). The so-called\none-dimensional reconstruction is characterised by bright rows that extend\nhundreds of nanometers in the [1-10] direction and have a periodicity of 2.52\nnm in [001] in STM. It is concluded that this reconstruction is the result of a\nperiodic faceting to expose {111}-type planes with a lower surface energy."
    },
    {
        "anchor": "Robust Room-Temperature Quantum Spin Hall Effect in\n  Methyl-functionalized InBi honeycomb film: Two-dimensional (2D) group-III-V honeycomb films have attracted significant\ninterest for their potential application in fields of quantum computing and\nnanoeletronics. Searching for 2D III-V films with high structural stability and\nlarge-gap are crucial for the realizations of dissipationless transport edge\nstates using quantum spin Hall (QSH) effect. Based on first-principles\ncalculations, we predict that the methyl-functionalized InBi monolayer\n(InBiCH3) has no dynamic instability, and host a QSH state with a band gap as\nlarge as 0.29 eV, exhibiting an interesting electronic behavior viable for\nroom-temperature applications. The topological characteristic is confirmed by\ns-pxy bands inversion, topological invariant Z2 number, and the time-reversal\nsymmetry protected helical edge states. Noticeably, the QSH states are tunable\nand robust against the mechanical strain, electric field and different levels\nof methyl coverages. We also find that InBiCH3 supported on h-BN substrate\nmaintains a nontrivial QSH state, which harbors the edge states lying within\nthe band gap of substrate. These findings demonstrate that the\nmethyl-functionalized III-V films may be a good QSH platform for device design\nand fabrication in spintronics.",
        "positive": "Low-Frequency Current Fluctuations in Graphene-like Exfoliated\n  Thin-Films of Topological Insulators: We report on the low-frequency current fluctuations and electronic noise in\nthin-films made of bismuth selenide topological insulators. The films were\nprepared via the graphene-like mechanical exfoliation and used as the current\nconducting channels in the four- and two-contact devices. Analysis of the\nresistance dependence on the film thickness indicates that the surface\ncontribution to conductance is dominant in our samples. It was established that\nthe current fluctuations have the noise spectrum close to the pure 1/f in the\nfrequency range from 1 to 10 kHz (f is the frequency). The relative noise\namplitude S/I^2 for the examined films was increasing from ~5x10^-8 to 5x10^-6\n(1/Hz) as the resistance of the channels varied from ~10^3 to 10^5 Ohms. The\nobtained noise data is important for understanding electron transport through\nthe surface and volume of topological insulators, and proposed applications of\nthis class of materials."
    },
    {
        "anchor": "Analysis of electron-positron momentum spectra of metallic alloys as\n  supported by first-principles calculations: Electron-positron momentum distributions measured by the coincidence Doppler\nbroadening method can be used in the chemical analysis of the annihilation\nenvironment, typically a vacancy-impurity complex in a solid. In the present\nwork, we study possibilities for a quantitative analysis, i.e., for\ndistinguishing the average numbers of different atomic species around the\ndefect. First-principles electronic structure calculations self-consistently\ndetermining electron and positron densities and ion positions are performed for\nvacancy-solute complexes in Al-Cu, Al-Mg-Cu, and Al-Mg-Cu-Ag alloys. The\nensuing simulated coincidence Doppler broadening spectra are compared with\nmeasured ones for defect identification. A linear fitting procedure, which uses\nthe spectra for positrons trapped at vacancies in pure constituent metals as\ncomponents, has previously been employed to find the relative percentages of\ndifferent atomic species around the vacancy [A. Somoza et al. Phys. Rev. B 65,\n094107 (2002)]. We test the reliability of the procedure by the help of\nfirst-principles results for vacancy-solute complexes and vacancies in\nconstituent metals.",
        "positive": "A self-similar ordered structure with a non-crystallographic point\n  symmetry: A new class of self-similar ordered structures with non-crystallographic\npoint symmetries is presented. Each of these structures, named\nsuperquasicrystals, is given as a section of a higher-dimensional \"crystal\"\nwith recursive superlattice structures. Such structures turn out to be\nlimit-quasiperiodic, distinguishing themselves from quasicrystals which are\nquasiperiodic. There exist a few real materials that seem to be promising\ncandidates for superquasicrystals."
    },
    {
        "anchor": "Origins of minimized lattice thermal conductivity and enhanced\n  thermoelectric performance in WS2/WSe2 lateral superlattice: We report a configuration strategy for improving the thermoelectric (TE)\nperformance of two-dimensional (2D) transition metal dichalcogenide (TMDC) WS2\nbased on the experimentally prepared WS2/WSe2 lateral superlattice (LS)\ncrystal. On the basis of density function theory combined with Boltzmann\ntransport equation, we show that the TE figure of merit zT of monolayer WS2 is\nremarkably enhanced when forming into a WS2/WSe2 LS crystal. This is primarily\nascribed to the almost halved lattice thermal conductivity due to the enhanced\nanharmonic processes. Electronic transport properties parallel (xx) and\nperpendicular (yy) to the superlattice period are highly symmetric for both p-\nand n-doped LS owing to the nearly isotropic lifetime of charger carriers. The\nspin-orbital effect causes a significant split of conduction band and leads to\nthree-fold degenerate sub-bands and high density of states (DOS), which offers\nopportunity to obtain the high n-type Seebeck coefficient (S). Interestingly,\nthe separated degenerate sub-bands and upper conduction band in monolayer WS2\nform a remarkable stairlike DOS, yielding a higher S. The hole carriers with\nmuch higher mobility than electrons reveal the high p-type power factor and the\npotential to be good p-type TE materials with optimal zT exceeds 1 at 400K in\nWS2/WSe2 LS.",
        "positive": "Mn L3,2 X-ray Absorption Spectroscopy And Magnetic Circular Dichroism In\n  Ferromagnetic (Ga,Mn)P: We have measured the X-ray absorption (XAS) and X-ray magnetic circular\ndichroism (XMCD) at the Mn L3,2 edges in ferromagnetic Ga1-xMnxP films for\n0.018<x<0.042. Large XMCD asymmetries at the L3 edge indicate significant\nspin-polarization of the density of states at the Fermi energy. The spectral\nshapes of the XAS and XMCD are nearly identical with those for Ga1-xMnxAs\nindicating that the hybridization of Mn d states and anion p states is similar\nin the two materials. Finally, compensation with sulfur donors not only lowers\nthe ferromagnetic Curie temperature but also reduces the spin polarization of\nthe hole states."
    },
    {
        "anchor": "Core-hole-induced dynamical effects in the x-ray emission spectrum of\n  liquid methanol: We compute the x-ray emission spectrum (XES) of liquid methanol, with the\ndynamical effects that result from the creation of the core hole included in a\nsemiclassical way. Our method closely reproduces a fully quantum mechanical\ndescription of the dynamical effects for relevant one-dimensional models of the\nhydrogen-bonded methanol molecules. For the liquid we find excellent agreement\nwith the experimental spectrum, including the large isotope effect in the first\nsplit peak. The dynamical effects depend sensitively on the initial structure\nin terms of the local hydrogen-bonding (H-bonding) character; non-donor\nmolecules contribute mainly to the high-energy peak while molecules with a\nstrong donated H-bond contribute to the peak at lower energy. The spectrum thus\nreflects the initial structure mediated by the dynamical effects that are,\nhowever, seen to be crucial in order to reproduce the intensity distribution of\nthe recently measured spectrum.",
        "positive": "\"Graphene-Like\" Exfoliation of Atomically-Thin Bismuth Telluride Films: We report on graphene-like exfoliation of the large-area crystalline films\nand ribbons of bismuth telluride with the thicknesses of a few atoms. It is\ndemonstrated that bismuth telluride, the most important material for\nthermoelectric industry, can be mechanically separated into its building blocks\n-[Te-Bi-Te-Bi-Te]- atomic five-folds with the thickness of ~1 nm and even\nfurther - to subunits with smaller thicknesses. The atomically-thin crystals\ncan be structured into suspended crystalline ribbons providing quantum\nconfinement in two dimensions. The quasi two-dimensional (2-D) crystals of\nbismuth telluride revealed high electrical conductivity. The proposed\natomic-layer engineering of bismuth telluride opens up a principally new route\nfor drastic enhancement of the thermoelectric figure of merit."
    },
    {
        "anchor": "The Crossover from Impurity to Valence Band in Diluted Magnetic\n  Semiconductors: The Role of the Coulomb Attraction by Acceptor: The crossover between an impurity band (IB) and a valence band (VB) regime as\na function of the magnetic impurity concentration in models for diluted\nmagnetic semiconductors (DMS) is studied systematically by taking into\nconsideration the Coulomb attraction between the carriers and the magnetic\nimpurities. The density of states and the ferromagnetic transition temperature\nof a Spin-Fermion model applied to DMS are evaluated using Dynamical Mean-Field\nTheory (DMFT) and Monte Carlo (MC) calculations. It is shown that the addition\nof a square-well-like attractive potential can generate an IB at small enough\nMn doping $x$ for values of the $p-d$ exchange $J$ that are not strong enough\nto generate one by themselves. We observe that the IB merges with the VB when\n$x >= x_c$ where $x_c$ is a function of $J$ and the Coulomb attraction strength\n$V$. Using MC calculations, we demonstrate that the range of the Coulomb\nattraction plays an important role. While the on-site attraction, that has been\nused in previous numerical simulations, effectively renormalizes $J$ for all\nvalues of $x$, an unphysical result, a nearest-neighbor range attraction\nrenormalizes $J$ only at very low dopings, i.e., until the bound holes wave\nfunctions start to overlap. Thus, our results indicate that the Coulomb\nattraction can be neglected to study Mn doped GaSb, GaAs, and GaP in the\nrelevant doping regimes, but it should be included in the case of Mn doped GaN\nthat is expected to be in the IB regime.",
        "positive": "Abnormal behavior of Cs polyoxides under high pressure: High-pressure can transform the structures and compositions of materials\neither by changing the relative strengths of bonds or by altering the oxidation\nstates of atoms. Both effects cause unconventional compositions in novel\ncompounds that have been synthesized or predicted in large numbers in the past\ndecade. What naturally follows is a question: what if pressure imposes strong\neffects on both chemical bonds and atomic orbitals in the same material. A\nsystematic DFT and crystal structure search study of Cs polyoxides under high\npressure shows a striking transition of chemistry due to the activation of the\nCs 5p core electrons. Opposing to the general trend of polyoxides, the O-O\nbonds disappear in Cs polyoxides and Cs and O atoms form molecules and\nmonolayers with strong Cs-O covalent bonds. Especially, the abnormal transition\nof structure and chemical bonds happens to CsO, a solid peroxide that is stable\nunder ambient pressure, at 221 GPa, which can be accessed by current\nhigh-pressure experiments."
    },
    {
        "anchor": "Temperature dependence in interatomic potentials and an improved\n  potential for Ti: The process of deriving an interatomic potentials represents an attempt to\nintegrate out the electronic degrees of freedom from the full quantum\ndescription of a condensed matter system. In practice it is the derivatives of\nthe interatomic potentials which are used in molecular dynamics, as a model for\nthe forces on a system. These forces should be the derivative of the free\nenergy of the electronic system, which includes contributions from the entropy\nof the electronic states. This free energy is weakly temperature dependent, and\nalthough this can be safely neglected in many cases there are some systems\nwhere the electronic entropy plays a significant role. Here a method is\nproposed to incorporate electronic entropy in the Sommerfeld approximation into\nempirical potentials. The method is applied as a correction to an existing\npotential for titanium. Thermal properties of the new model are calculated, and\na simple method for fixing the melting point and solid-solid phase transition\ntemperature for existing models fitted to zero temperature data is presented.",
        "positive": "Landau Theory of Altermagnetism: We formulate a Landau theory for altermagnets, a class of colinear\ncompensated magnets with spin-split bands. Starting from the non-relativistic\nlimit, this Landau theory goes beyond a conventional analysis by including\nspin-space symmetries, providing a simple framework for understanding the key\nfeatures of this family of materials. We find a set of multipolar secondary\norder parameters connecting existing ideas about the spin symmetries of these\nsystems, their order parameters and the effect of non-zero spin-orbit coupling.\nWe account for several features of canonical altermagnets such as RuO$_2$, MnTe\nand CuF$_2$ that go beyond symmetry alone, relating the order parameter to key\nobservables such as magnetization, anomalous Hall conductivity and\nmagneto-elastic and magneto-optical probes. Finally, we comment on\ngeneralizations of our framework to a wider family of exotic magnetic systems\nderiving from the zero spin-orbit coupled limit."
    },
    {
        "anchor": "Room-temperature multiferroic hexagonal LuFeO$_3$ films: The crystal and magnetic structures of single-crystalline hexagonal LuFeO$_3$\nfilms have been studied using x-ray, electron and neutron diffraction methods.\nThe polar structure of these films are found to persist up to 1050 K; and the\nswitchability of the polar behavior is observed at room temperature, indicating\nferroelectricity. An antiferromagnetic order was shown to occur below 440 K,\nfollowed by a spin reorientation resulting in a weak ferromagnetic order below\n130 K. This observation of coexisting multiple ferroic orders demonstrates that\nhexagonal LuFeO$_3$ films are room-temperature multiferroics.",
        "positive": "Structural evolution of bismuth sodium titanate induced by A-site\n  non-stoichiometry: Neutron powder diffraction studies: We performed neutron powder diffraction measurements on\n(Bi$_{0.5}$Na$_{0.5+x}$)TiO$_3$ and (Bi$_{0.5+y}$Na$_{0.5}$)TiO$_3$ to study\nstructural evolution induced by the non-stoichiometry. Despite the\nnon-stoichiometry, the local structure ($r$$\\leq$ 3.5 {\\AA}) from the pair\ndistribution function analysis is barely affected by the sodium deficit of up\nto -5 mol%. With increasing pair distance, however, the atomic pair\ncorrelations weaken due to the disorder caused by the sodium deficiency.\nAlthough the sodium and the bismuth share the same crystallographic site, their\nnon-stoichiometry have rather opposite effects as revealed from a distinctive\ndistortion of the Bragg peaks. In addition, Rietveld refinement demonstrates\nthat the octahedral tilting is continually suppressed by the sodium deficit of\nup to -5 mol%. This is contrary to the effect of the bismuth deficiency, which\nenhances the octahedral tilting."
    },
    {
        "anchor": "The layered compound CaClFeP is an Arsenic-free high $T_c$ iron-pnictide: We first analyze why the iron pnictides with high $T_c$ superconductivity so\nfar are As-based, by the Hund's rule correlation picture, then examine the\nP-based and Sb-based cases, respectively. Consequently, we propose that CaClFeP\nwith ZrCuSiAs-type structure is an As-free high $T_c$ iron-pnictide. The\nsubsequent density functional theory calculations show that the ground state of\nCaClFeP is of a collinearly antiferromagnetic order on Fe moments with\nstructural distortion, resulting from the interplay between the strong nearest\nand next-nearest neighbor antiferromagnetic superexchange interactions bridged\nby P atoms, similar as the As-based pnictides. The other P-based pnictides are\neither nonmagnetic or magnetic but with weak exchange interactions. The\nSb-based pnictides unlikely show high $T_c$ superconductivity because of the\nexistence of robust ferromagnetic order.",
        "positive": "High-pressure phase behaviors of titanium dioxide revealed by a\n  $\u0394$-learning potential: Titanium dioxide has been extensively studied in the rutile or anatase\nphases, while its high-pressure phases are less well understood, despite that\nmany are thought to have interesting optical, mechanical and electrochemical\nproperties. First-principles methods such as density functional theory (DFT)\nare often used to compute the enthalpies of TiO$_2$ phases at 0~K, but they are\nexpensive and thus impractical for long time-scale and large system-size\nsimulations at finite temperatures. On the other hand, cheap empirical\npotentials fail to capture the relative stablities of the various polymorphs.\nTo model the thermodynamic behaviors of ambient and high-pressure phases of\nTiO$_2$, we design an empirical model as a baseline, and then train a machine\nlearning potential based on the difference between the DFT data and the\nempirical model. This so-called $\\Delta$-learning potential contains long-range\nelectrostatic interactions, and predicts the 0~K enthalpies of stable TiO$_2$\nphases that are in good agreement with DFT. We construct a pressure-temperature\nphase diagram of TiO$_2$ in the range $0<P<70$~GPa and $100<T<1500$~K. We then\nsimulate dynamic phase transition processes, by compressing anatase at\ndifferent temperatures. At 300~K, we observe predominantly\nanatase-to-baddeleyite transformation at about 20~GPa, via a martensitic\ntwo-step mechanism with highly ordered and collective atomic motion. At 2000~K,\nanatase can transform into cotunnite around 45-55~GPa in a thermally-activated\nand probabilistic manner, accompanied by diffusive movement of oxygen atoms.\nThe pressures computed for these transitions show good agreement with\nexperiments. Our results shed light on how to synthesize and stabilize\nhigh-pressure TiO$_2$ phases, and our method is generally applicable to other\nfunctional materials with multiple polymorphs."
    },
    {
        "anchor": "Solvent Exfoliation of Electronic-Grade, Two-Dimensional Black\n  Phosphorus: Solution dispersions of two-dimensional (2D) black phosphorus (BP), often\nreferred to as phosphorene, are achieved by solvent exfoliation. These\npristine, electronic-grade BP dispersions are produced with anhydrous, organic\nsolvents in a sealed tip ultrasonication system, which circumvents BP\ndegradation that would otherwise occur via solvated oxygen or water. Among\nconventional solvents, n-methyl-pyrrolidone (NMP) is found to provide stable,\nhighly concentrated (~0.4 mg/mL) BP dispersions. Atomic force microscopy,\nscanning electron microscopy, transmission electron microscopy, Raman\nspectroscopy, and X-ray photoelectron spectroscopy show that the structure and\nchemistry of solvent-exfoliated BP nanosheets are comparable to mechanically\nexfoliated BP flakes. Additionally, residual NMP from the liquid-phase\nprocessing suppresses the rate of BP oxidation in ambient conditions.\nSolvent-exfoliated BP nanosheet field-effect transistors (FETs) exhibit\nambipolar behavior with current on/off ratios and mobilities up to ~10000 and\n~50 cm^2/(V*s), respectively. Overall, this study shows that stable, highly\nconcentrated, electronic-grade 2D BP dispersions can be realized by scalable\nsolvent exfoliation, thereby presenting opportunities for large-area,\nhigh-performance BP device applications.",
        "positive": "Photophysics of charge-transfer excitons in thin films of \u03c0-conjugated\n  polymers: We develop a theory of the electronic structure and photophysics of\ninteracting chains of \\pi- conjugated polymers to understand the differences\nbetween solutions and films. While photoexcitation generates only the\nintrachain exciton in solutions, the optical exciton as well as weakly allowed\ncharge-transfer excitons are generated in films. We extend existing theories of\nthe lowest polaronpair and charge-transfer excitons to obtain descriptions of\nthe excited states of these interchain species, and show that a significant\nfraction of ultrafast photoinduced absorptions in films originate from the\nlowest charge-transfer exciton. Our proposed mechanism explains the\nsimultaneous observation of polaronlike induced absorption features peculiar to\nfilms in ultrafast spectroscopy and the absence of mobile charge carriers as\ndeduced from other experiments. We also show that there is a 1:1 correspondence\nbetween the essential states that describe the photophysics of single chains\nand of interacting chains that constitute thin films."
    },
    {
        "anchor": "L1$_0$ FePt thin films with tilted and in-plane magnetic anisotropy:\n  first-principles study: Ultrathin L1$_0$ films with different $c$-axis orientations relative to the\nfilm plane are promising candidates for data storage materials. In this work,\nwithin the framework of density functional theory, we calculated the magnetic\nproperties of ultrathin L1$_0$ (111) and (010) films with thicknesses ranging\nfrom 4 to 16 atomic monolayers (from about 0.8 to 3.5~nm). The highest average\nmagnetic moments are observed for the thinnest films considered, and with\nincreasing film thickness, the values converge towards the magnetic moment for\nbulk. The observed increase comes mainly from enhanced moments in the two\natomic monolayers closest to the surface of the films. The easy axis of\nmagnetization of (111) films prefers an alignment close to the tetragonal axis,\nan example of tilted magnetic anisotropy. The 6-monolayer (111) film (about\n1.3~nm thick) inclines the easy axis of magnetization of about 45{\\deg} to the\nfilm plane, which can find use in applications. The (010) films show an\nin-plane easy magnetization axis in a unique L1$_0$ tetragonal direction. This\nis an unusual type of in-plane anisotropy, as the particular direction\npreference is very strong. The computational results encourage further\nexperimental studies of L1$_0$ systems with tilted and in-plane fixed magnetic\nanisotropy.",
        "positive": "Large Second Harmonic Kerr rotation in GaFeO3 thin films on YSZ buffered\n  Silicon: Epitaxial thin films of gallium iron oxide (GaFeO3) are grown on (001)\nsilicon by pulsed laser deposition (PLD) using yttrium-stabilized zirconia\n(YSZ) buffer layer. The crystalline template buffer layer is in-situ PLD grown\nthrough the step of high temperature stripping of the intrinsic silicon surface\noxide. The X-ray diffraction pattern shows c-axis orientation of YSZ and b-axis\norientation of GaFeO3 on Si (100) substrate. The ferromagnetic transition\ntemperature (TC ~ 215 K) is in good agreement with the bulk data. The films\nshow a large nonlinear second harmonic Kerr rotation of ~15 degrees in the\nferromagnetic state."
    },
    {
        "anchor": "Implications of magnetic and magnetodielectric behavior of GdCrTiO5: We have carried out dc magnetization (M), heat-capacity (C) and dielectric\nstudies down to 2K for the compound GdCrTiO5, crystallizing in orthorhombic\nPbam structure, in which well-known multiferroics RMn2O5 (R= Rare-earths) form.\nThe points of emphasis are: (i) The magnetic ordering temperature of Cr appears\nto be suppressed compared to that in isostructural Nd counterpart, NdCrTiO5,\nfor which the Neel temperature is about 21 K. This finding on the Gd compound\nsuggests that Nd 4f orbital plays a role on the magnetism of Cr in contrast to\na proposal long ago. (ii) Dielectric constant does not exhibit any notable\nfeature below about 30 K in the absence of external magnetic field, but a peak\nappears and gets stronger with the application of external magnetic fields,\nsupporting the existence of magnetodielectric coupling. (iii) The dielectric\nanomalies appear even near 100 K, which can be attributed to short-range\nmagnetic-order. We also observe a gain in spectral weight below about 150 K in\nRaman spectra in the frequency range 150 to 400 cm-1, which could be magnetic\nin origin supporting short-range magnetic order. It is of interest to explore\nwhether geometrically frustration plays any role on the dielectric properties\nof this family, as in the case of RMn2O5.",
        "positive": "PASCal: A principal-axis strain calculator for thermal expansion and\n  compressibility determination: We describe a web-based tool (PASCal; Principal Axis Strain Calculator) aimed\nat simplifying the determination of principal coefficients of thermal expansion\nand compressibilities from variable-temperature and variable-pressure lattice\nparameter data. In a series of three case studies, we use PASCal to re-analyse\npreviously-published lattice parameter data and show that additional scientific\ninsight is obtainable in each case. First, the two-dimensional metal-organic\nframework Cu-SIP-3 is found to exhibit the strongest area-negative thermal\nexpansion (NTE) effect yet observed; second, the widely-used explosive HMX\nexhibits much stronger mechanical anisotropy than had previously been\nanticipated, including uniaxial NTE driven by thermal changes in molecular\nconformation; and, third, the high-pressure form of the mineral malayaite is\nshown to exhibit a strong negative linear compressibility (NLC) effect that\narises from correlated tilting of SnO6 and SiO4 coordination polyhedra."
    },
    {
        "anchor": "A physics-informed neural network for quantifying the microstructure\n  properties of polycrystalline Nickel using ultrasound data: We employ physics-informed neural networks (PINNs) to quantify the\nmicrostructure of a polycrystalline Nickel by computing the spatial variation\nof compliance coefficients (compressibility, stiffness and rigidity) of the\nmaterial. The PINN is supervised with realistic ultrasonic surface acoustic\nwavefield data acquired at an ultrasonic frequency of 5 MHz for the\npolycrystalline material. The ultrasonic wavefield data is represented as a\ndeformation on the top surface of the material with the deformation measured\nusing the method of laser vibrometry. The ultrasonic data is further\ncomplemented with wavefield data generated using a finite element based solver.\nThe neural network is physically-informed by the in-plane and out-of-plane\nelastic wave equations and its convergence is accelerated using adaptive\nactivation functions. The overarching goal of this work is to infer the spatial\nvariation of compliance coefficients of materials using PINNs, which for\nultrasound involves the spatially varying speed of the elastic waves. More\nbroadly, the resulting PINN based surrogate model shows a promising approach\nfor solving ill-posed inverse problems, often encountered in the\nnon-destructive evaluation of materials.",
        "positive": "Modeling slow deformation of polygonal particles using DEM: We introduce two improvements in the numerical scheme to simulate collision\nand slow shearing of irregular particles. First, we propose an alternative\napproach based on simple relations to compute the frictional contact forces.\nThe approach improves efficiency and accuracy of the Discrete Element Method\n(DEM) when modeling the dynamics of the granular packing. We determine the\nproper upper limit for the integration step in the standard numerical scheme\nusing a wide range of material parameters. To this end, we study the kinetic\nenergy decay in a stress controlled test between two particles. Second, we show\nthat the usual way of defining the contact plane between two polygonal\nparticles is, in general, not unique which leads to discontinuities in the\ndirection of the contact plane while particles move. To solve this drawback, we\nintroduce an accurate definition for the contact plane based on the shape of\nthe overlap area between touching particles, which evolves continuously in\ntime."
    },
    {
        "anchor": "Physical properties and thermal stability of Fe5GeTe2 single crystals: The magnetic and transport properties of Fe-deficient Fe5GeTe2 single\ncrystals (Fe5-xGeTe2 with x~0.3) were studied and the impact of thermal\nprocessing was explored. Quenching crystals from the growth temperature has\nbeen previously shown to produce a metastable state that undergoes a strongly\nhysteretic first-order transition upon cooling below ~100K. The first-order\ntransition impacts the magnetic properties, yielding an enhancement in the\nCurie temperature T_C from 270 to 310K. In the present work, T_HT ~550K has\nbeen identified as the temperature above which metastable crystals are obtained\nvia quenching. Diffraction experiments reveal a structural change at this\ntemperature, and significant stacking disorder occurs when samples are slowly\ncooled through this temperature range. The transport properties are\ndemonstrated to be similar regardless of the crystal's thermal history. The\nscattering of charge carriers appears to be dominated by moments fluctuating on\nthe Fe(1) sublattice, which remain dynamic down to 100-120K. Maxima in the\nmagnetoresistance and anomalous Hall resistance are observed near 120K. The\nHall and Seebeck coefficients are also impacted by magnetic ordering on the\nFe(1) sublattice. The data suggest that both electrons and holes contribute to\nconduction above 120K, but that electrons dominate at lower temperature when\nall of the Fe sublattices are magnetically ordered. This study demonstrates a\nstrong coupling of the magnetism and transport properties in Fe5-xGeTe2 and\ncomplements the previous results that demonstrated strong magnetoelastic\ncoupling as the Fe(1) moments order. The published version of this manuscript\nis DOI:10.1103/PhysRevMaterials.3.104401 (2019)",
        "positive": "Effect of Synchrotron Polarization in Grazing Incidence X-ray\n  Fluorescence analysis: Total reflection x-ray fluorescence (TXRF) spectroscopy has seen a remarkable\nprogress over the past years. Numerous applications in basic and applied\nsciences prove its importance. The large spectral background which is a major\ndetrimental factor in the conventional x-ray fluorescence technique, limits the\nelement detection sensitivities of the technique to ppm range. This spectral\nbackground reduces to a great extent in the TXRF technique due to the low\nextinction depth of the primary incident x-ray beam. In synchrotron radiation\n(SR) based TXRF measurements the spectral background reduces further because of\nthe polarization of the synchrotron x-ray beam. Here, we discuss in detail the\ninfluence of synchrotron polarization on the spectral background in a\nfluorescence spectrum and its significance towards TXRF detection\nsensitivities. We provide a detailed theoretical description and show that how\nanisotropic scattering probability densities of the Compton and Elastic\nscattered x-rays depend on the scattering angle ({\\theta}) and azimuthal angle\n({\\phi}) in the polarization plane of the SR beam."
    },
    {
        "anchor": "Calculating dispersion interactions using maximally-localized Wannier\n  functions: We investigate a recently developed approach [P. L. Silvestrelli, Phys. Rev.\nLett. 100, 053002 (2008); J. Phys. Chem. A 113, 5224 (2009)] that uses\nmaximally localized Wannier functions to evaluate the van der Waals\ncontribution to the total energy of a system calculated with density-functional\ntheory. We test it on a set of atomic and molecular dimers of increasing\ncomplexity (argon, methane, ethene, benzene, phthalocyanine, and copper\nphthalocyanine) and demonstrate that the method, as originally proposed, has a\nnumber of shortcomings that hamper its predictive power. In order to overcome\nthese problems, we have developed and implemented a number of improvements to\nthe method and show that these modifications give rise to calculated binding\nenergies and equilibrium geometries that are in closer agreement to results of\nquantum-chemical coupled-cluster calculations.",
        "positive": "Designing Perturbative Metamaterials from Discrete Models: From Veselago\n  lenses to topological insulators: Discrete models provide concise descriptions of complex physical phenomena,\nsuch as negative refraction, topological insulators, and Anderson localization.\nWhile there are multiple tools to obtain discrete models that demonstrate\nparticular phenomena, it remains a challenge to find metamaterial designs that\nreplicate the behavior of desired nontrivial discrete models. Here we solve\nthis problem by introducing a new class of metamaterial, which we term\n'perturbative metamaterial', consisting of weakly interacting unit cells. The\nweak interaction allows us to associate each element of the discrete model\n(individual masses and springs) to individual geometric features of the\nmetamaterial, thereby enabling a systematic design process. We demonstrate our\napproach by designing 2D mechanical metamaterials that realize Veselago lenses,\nzero-dispersion bands, and topological insulators. While our selected examples\nare within the mechanical domain, the same design principle can be applied to\nacoustic, thermal, and photonic metamaterials composed of weakly interacting\nunit cells."
    },
    {
        "anchor": "Mechanical and Electronic Properties of Ferromagnetic GaMnAs Using\n  Ultrafast Coherent Acoustic Phonons: Ultrafast two-color pump-probe measurements, involving coherent acoustic\nphonon (CAP) waves, have provided information simultaneously on the mechanical\nproperties and on the electronic structure of ferromagnetic GaMnAs. The elastic\nconstant C11 of Ga1-xMnxAs (0.03<x<0.07) are observed to be systematically\nsmaller than those of GaAs. Both C11 and Vs of GaMnAs are found to increase\nwith temperature (78 K<T<295 K), again in contrast to the opposite behavior in\nGaAs. In addition, the fundamental bandgap (at E0 critical point) of Ga1-xMnxAs\nis found to shift slightly to higher energies with Mn concentration.",
        "positive": "Ab-initio analysis of structural, electronic, and optical properties of\n  a-Si:H: We present a first-principles study of the structural, electronic, and\noptical properties of hydrogenated amorphous silicon (a-Si:H). To this end,\natomic configurations of a-Si:H with 72 and 576 atoms respectively are\ngenerated using molecular dynamics. Density functional theory calculations are\nthen applied to these configurations to obtain the electronic wave functions.\nThese are analyzed and characterized with respect to their localization and\ntheir contribution to the density of states, and are used for calculating\nab-initio absorption spectra of a-Si:H. The results show that both the size and\nthe defect structure of the configurations modify the electronic and optical\nproperties and in particular the value of the band gap. This value could be\nimproved by calculating quasi-particle (QP) corrections to the single-particle\nspectra using the G$_0$W$_0$ method. We find that the QP corrections can be\ndescribed by a set of scissors shift parameters, which can also be used in\ncalculations of larger structures."
    },
    {
        "anchor": "Coalescence constraints of many-body systems in one dimension: For one-dimensional many-body systems interacting via the \\textit{Coulomb\nforce} and with \\textit{arbitrary} external potential energy, we derive\n(\\textit{i}) the \\textit{node coalescence condition} for the wave function.\nThis condition rigorously proves the following: (\\textit{ii}) that the\nparticles satisfy \\textit{only} a node coalescence condition; (\\textit{iii})\nthat irrespective of their charge or statistics, the particles cannot coalesce;\n(\\textit{iv}) that the particles cannot cross each other, and must be ordered;\n(\\textit{v}) the particles are therefore distinguishable; (\\textit{vi}) as such\ntheir statistics are not significant; (\\textit{vii}) conclusions similar to\nthose of the spin-statistics theorem of quantum field theory are arrived at via\nnon-relativistic quantum mechanics; (\\textit{viii}) the noninteracting system\n\\textit{cannot} be employed as the lowest-order in a perturbation theory of the\ninteracting system. (\\textit{ix}) Finally, the coalescence condition for\nparticles with the short-ranged delta-function interaction and\n\\textit{arbitrary} external potential energy, is also derived. These particles\ncan coalesce and cross each other.",
        "positive": "Electronic Structure and Stability of Cs$_{2}$TiX$_{6}$ and\n  Cs$_{2}$ZrX$_{6}$ (X$=$Br,I) Vacancy Ordered Double Perovskites: Vacancy ordered halide perovskites have been extensively investigated as\npromising lead-free alternatives to halide perovskites for various\nopto-electronic applications. Among these Cs$_{2}$TiBr$_{6}$ has been reported\nas a stable absorber with interesting electronic and optical properties, such\nas a band-gap in the visible, and long carrier diffusion lengths. Yet, a\nthorough theoretical analysis of the exhibited properties is still missing in\norder to further assess its application potential from a materials design point\nof view. In this letter, we perform a detailed analysis for the established\nTi-based compounds and investigate the less-known materials based on Zr. We\ndiscuss in details their electronic properties and band symmetries, highlight\nthe similarity between the materials in terms of properties, and reveal limits\nfor tuning electronic and optical properties within this family of vacancy\nordered double perovskites that share the same electron configuration. We also\nshow the challenges to compute accurate and meaningful quasi-particle\ncorrections at GW level. Furthermore, we address their chemical stability\nagainst different decomposition reaction pathways, identifying stable regions\nfor the formation of all materials, while probing their mechanical stability\nemploying phonon calculations. We predict that Cs$_{2}$ZrI$_{6}$, a material\npractically unexplored to-date, shall exhibit a quasi-direct electronic\nband-gap well within the visible range, the smallest charge carrier effective\nmasses within the Cs$_{2}$BX$_{6}$ (B=Ti,Zr; X=Br, I) compounds, and a good\nchemical stability."
    },
    {
        "anchor": "Effects of deposition temperature on the mechanical and structural\n  properties of amorphous Al-Si-O thin films prepared by RF magnetron\n  sputtering: Aluminosilicate (Al-Si-O) thin films containing up to 31 at. % Al and 23 at.\n% Si were prepared by reactive RF magnetron co-sputtering. Mechanical and\nstructural properties were measured by indentation and specular reflectance\ninfrared spectroscopy at varying Si sputtering target power and substrate\ntemperature in the range 100 to 500 {\\deg}C. It was found that an increased\nsubstrate temperature and Al/Si ratio give denser structure and consequently\nhigher hardness (7.4 to 9.5 GPa) and reduced elastic modulus (85 to 93 GPa)\nwhile at the same time lower crack resistance (2.6 to 0.9 N). The intensity of\nthe infrared Si-O-Si/Al asymmetric stretching vibrations shows a linear\ndependence with respect to Al concentration. The Al-O-Al vibrational band (at\n1050 cm-1) shifts towards higher wavenumbers with increasing Al concentration\nwhich indicates a decrease of the bond length, evidencing denser structure and\nhigher residual stress, which is supported by the increased hardness. The same\nAl-O-Al vibrational band (at 1050 cm-1) shifts towards lower wavenumber with\nincreasing substrate temperature indicating an increase in the of the average\ncoordination number of Al.",
        "positive": "Interplay among Work Function, electronic structure and stoichiometry in\n  nanostructured vanadium oxides films: The work function is the parameter of greatest interest in many technological\napplications involving charge exchange mechanisms at the interface. The\npossibility to produce samples with a controlled work function is then\nparticularly interesting, albeit challenging. We synthetized nanostructured\nvanadium oxides films by a room temperature Supersonic Cluster Beam Deposition\nmethod, obtaining samples with tunable stoichiometry and work function (3.7-7\neV). We present an investigation of the electronic structure of several\nvanadium oxides films as a function of the oxygen content via in-situ Auger,\nvalence-band photoemission spectroscopy and work function measurements. The\nexperiments probed the partial 3d density of states, highlighting the presence\nof strong V3d-O2p and V3d-V4s hybridization which influence 3d occupation. We\nshow how controlling the stoichiometry of the sample implies a control over\nwork function, and that the access to nanoscale quantum confinement can be\nexploited to increase the work function of the sample relative to the bulk\nanalogue. In general, the knowledge of the interplay among work function,\nelectronic structure, and stoichiometry is strategic to match nanostructured\noxides to their target applications."
    },
    {
        "anchor": "A multi $k$-point nonadiabatic molecular dynamics for periodic systems: With the rapid development of ultra-fast experimental techniques used for\ncarrier dynamics in solid-state systems, a microscopic understanding of the\nrelated phenomena, particularly a first-principle calculation is highly\ndesirable. Non-adiabatic molecular dynamics (NAMD) offers a real-time direct\nsimulation of the carrier transfer or carrier thermalization. However, when\napplied to a periodic supercell, due to the $\\Gamma$-point phonon movement\nduring the molecular dynamics, there is no supercell electronic $k$-point\ncrossing during the NAMD simulation. This often leads to a significant\nunderestimation of the transition rate due to significant energy gaps in the\nsingle supercell $k$-point band structure. In this work, based on the surface\nhopping scheme used for NAMD, we propose a practical method to enable the\ncross-$k$ transition for a periodic system. We demonstrate our formalism by\nshowing that the hot electron thermalization process by the multi $k$-point\nNAMD in a small supercell is equivalent to such simulation in a large supercell\nwith single $\\Gamma$ $k$-point. The hot carrier thermalization process in the\nbulk silicon is also carried out and compared with the recent ultra-fast\nexperiments with excellent agreements.",
        "positive": "Realizing an Epitaxial Stanene with an Insulating Bandgap: Stanene, a single atomic layer of Sn in a honeycomb lattice, is predicted a\ncandidate wide bandgap two-dimensional (2D) topological insulator and can host\nintriguing topological states of matter such as quantum anomalous Hall effect\nand topological superconductivity with different surface modifications. Despite\nintensive research efforts, one still cannot obtain bulk-insulating stanene\nsamples-a prerequisite for any transport studies and applications of stanene.\nHere we show the experimental realization of an epitaxial stanene with an\ninsulating bulk bandgap by using PbTe(111) substrates. With low-temperature\nmolecular beam epitaxy, we are able to grow single layer stanene on PbTe(111).\nIn-situ angle-resolved photoemission spectroscopy shows the characteristic\nstanene bands with its Fermi level lying in the bandgap. Doping Sr in PbTe\nremoves the substrate states located in the stanene gap, resulting in a stanene\nsample with truly insulating bulk. This experimental progress paves the way for\nstudies of stanene-based topological quantum effects."
    },
    {
        "anchor": "Universal theory of spin-momentum-orbital-site locking: Spin textures, i.e., the distribution of spin polarization vectors in\nreciprocal space, exhibit diverse patterns determined by symmetry constraints,\nresulting in a variety of spintronic phenomena. Here, we propose a universal\ntheory to comprehensively describe the nature of spin textures by incorporating\nthree symmetry flavors of reciprocal wavevector, atomic orbital and atomic\nsite. Such approach enables us to establish a complete classification of spin\ntextures constrained by the little co-group and predict unprecedentedly\nreported spin texture types, such as Zeeman-type spin splitting in\nantiferromagnets and quadratic spin texture. To examine the impact of atomic\norbitals and sites, we predict orbital-dependent spin texture and anisotropic\nspin-momentum-site locking effects and corresponding material candidates\nvalidated through first-principles calculations. Our theory not only covers all\npossible spin textures in crystal solids described by magnetic space groups,\nbut also introduces new possibilities for designing innovative spin textures by\nthe coupling of multiple degrees of freedom.",
        "positive": "Complete crystallographic, spin-electronic and magnetic structure of\n  (Co0.2Cr0.2Fe0.2Mn0.2Ni0.2)3O4: Unraveling the suppression of entropy in high\n  entropy oxides: High entropy oxides (HEOs) are a rapidly emerging class of functional\nmaterials consisting of multiple principal cations. The original paradigm of\nHEOs assumes cationic occupations with the highest possible configurational\nentropy allowed by the composition and crystallographic structure. However, the\nfundamental question remains on the actual degree of configurational disorder\nin HEOs, especially, in systems with a low enthalpy barriers for cation\nanti-site mixing. Considering the experimental limitations due to the presence\nof multiple principal cations in HEOs, here we utilize a robust and\ncross-referenced characterization approach using soft X-ray magnetic circular\ndichroism, hard X-ray absorption spectroscopy, M\\\"ossbauer spectroscopy,\nneutron powder diffraction and SQUID magnetometry to study the competition\nbetween crystal field stabilization energy and configurational entropy\ngoverning the cation occupation in a spinel HEO (S-HEO),\n(Co$_{0.2}$Cr$_{0.2}$Fe$_{0.2}$Mn$_{0.2}$Ni$_{0.2}$)$_3$O$_4$. In contrast to\nthe previous studies, the derived complete structural and spin-electronic\nmodel,\n(Co$_{0.6}$Fe$_{0.4}$)(Cr$_{0.3}$Fe$_{0.1}$Mn$_{0.3}$Ni$_{0.3}$)$_2$O$_4$,\nhighlights a significant deviation from the hitherto assumed paradigm of\nentropy-driven non-preferential distribution of cations in HEOs. An immediate\ncorrelation of this result can be drawn with bulk as well as the local element\nspecific magnetic properties, which are intrinsically dictated by cationic\noccupations in spinels. The real local lattice picture presented here provides\nan alternate viewpoint on ionic arrangement in HEOs, which is of fundamental\ninterest for predicting and designing their structure-dependent\nfunctionalities."
    },
    {
        "anchor": "Gold nanowires and their chemical modifications: Equilibrium structure, local densities of states, and electronic transport in\na gold nanowire made of a four-atom chain supported by two gold electrodes,\nwhich has been imaged recently by high-resolution electron microscopy, and\nchemical modification of the wire via the adsorption of a methylthiol molecule,\nare investigated with ab-initio local density functional simulations. In the\nbare wire at the imaged geometry the middle two atoms dimerize, and the\nstructure is strongly modified by the adsorption of the molecule with an\naccompanying increase of the ballistic conductance through the wire.",
        "positive": "On the energetic origin of self-limiting trenches formed around Ge/Si\n  quantum dots: At high growth temperatures, the misfit strain at the boundary of Ge quantum\ndots on Si(001) is relieved by formation of trenches around the base of the\nislands. The depth of the trenches has been observed to saturate at a level\nthat depends on the base-width of the islands. Using finite element\nsimulations, we show that the self-limiting nature of trench depth is due to a\ncompetition between the elastic relaxation energy gained by the formation of\nthe trench and the surface energy cost for creating the trench. Our simulations\npredict a linear increase of the trench depth with the island radius, in\nquantitative agreement with the experimental observations of Drucker and\ncoworkers."
    },
    {
        "anchor": "A note on the electrochemical nature of the thermoelectric power: While thermoelectric transport theory is well established and widely applied,\nthere remains some degree of confusion on the proper thermodynamic definition\nof the Seebeck coefficient (or thermoelectric power) which is a measure of the\nstrength of the mutual interaction between electric charge transport and heat\ntransport. Indeed, as one considers a thermoelectric system, it is not always\nclear whether the Seebeck coefficient is to be related to the gradient of the\nsystem's chemical potential or to the gradient of its electrochemical\npotential. This pedagogical article aims to shed light on this confusion and\nclarify the thermodynamic definition of the thermoelectric coupling. First, we\nrecall how the Seebeck coefficient is experimentally determined. We then turn\nto the analysis of the relationship between the thermoelectric power and the\nrelevant potentials in the thermoelectric system: As the definitions of the\nchemical and electrochemical potentials are clarified, we show that, with a\nproper consideration of each potential, one may derive the Seebeck coefficient\nof a non-degenerate semiconductor without the need to introduce a contact\npotential as seen sometimes in the literature. Furthermore, we demonstrate that\nthe phenomenological expression of the electrical current resulting from\nthermoelectric effects may be directly obtained from the drift-diffusion\nequation.",
        "positive": "Theoretical insights on structural, electronic and thermoelectric\n  properties of inorganic biphenylene: non-benzenoid Boron nitride: The first-principles calculations predict a stable biphenylene carbon network\n(BPN) like the Boron-nitride structure named inorganic biphenylene network\n(I-BPN). A comparison has been done between BPN and I-BPN to examine the\nstability of the I-BPN monolayer. We calculate the formation energy, phonon\ndispersion and mechanical parameters: young modulus and Poisson ratio for\nmechanical stability. It has been found that the stability of I-BPN is\ncomparable with the BPN. The lattice transport properties reveal that the\nphonon thermal conductivity of I-BPN is 10th order low than the BPN. The\nelectronic band structure reveals that I-BPN is a semiconductor with an\nindirect bandgap of 1.88 eV with valence band maximum (VBM) at Y and conduction\nband maximum (CBM) at the X high symmetry point. In addition, the\nthermoelectric parameters, such as the seebeck coefficient, show the highest\npeak value of 0.00292 V/K at 324K. Electronic transport properties reveal that\nI-BPN is highly anisotropic along the x and y-axes. Furthermore, the\nthermoelectric power factor as a function of chemical potential shows a peak\nvalue of 0.0056 W/mK2 (900K) along the x-axis in the p-type doping region. An\nelectronic figure of merit shows an amplified peak approach to 1. The total\nfigure of merit (including lattice transport parameters) shows peak values of\n0.378 (0.21) for p-type and 0.24 (0.198) n-type regions along the x(y)\ndirection. It is notice that the obtain ZT peaks values are higher than any B-N\ncompositions."
    },
    {
        "anchor": "Phase transition in saturated porous media: pore-fluid segregation in\n  consolidation: Consider the consolidation process typical of soils, this phenomenon is\nexpected not to exhibit a unique state of equilibrium, depending on the\n\\textit{external loading} and the constitutive parameters. Beyond the standard\nsolution, also pore-fluid segregation, which is typically associated with\nfluidization of the granular material, can arise. Pore-fluid segregation has\nbeen recognized as a phenomenon typical of the short time behavior of a\nsaturated porous slab or a saturated porous sphere, during consolidation. In\nboth circumstances Biot's three dimensional model provides time increasing\nvalues of the water pressure (and fluid mass density) at the center of the slab\n(or of the sphere), at early times, if the Lam\\'{e} constant $\\mu$ of the\nskeleton is different from zero. This localized pore-fluid segregation is known\nin the literature as Mandel--Cryer effect. In this paper a non linear\nporomechanical model is formulated. The model is able to describe the\noccurrence of two states of equilibrium and the switching from one to the other\nby considering a kind of \\textit{phase transition}. Extending classical Biot's\ntheory a more than quadratic strain energy potential is postulated, depending\non the strain of the porous material and the variation of the fluid mass\ndensity (measured with respect to the skeleton reference volume). When the\nconsolidating pressure is strong enough the existence of two distinct minima is\nproven.",
        "positive": "Understanding coupled mass-heat transport in fluids by\n  approach-to-equilibrium molecular dynamics: We present a generalization of AEMD approach, routinely applied to estimate\nthermal conductivity, to the more general case in which Soret and Dufour\neffects determine a coupled heat-mass transfer. We show that, by starting from\nmicroscopical definitions of heat and mass currents, conservation laws dictates\nthe form of the differential equations governing the time evolution. In\nparticular, we focus to the well specific case in which a closed-form solution\nof the system is possible and derive the analytical form of time-evolution of\ntemperature and concentration scalar fields in the case in which step-like\ninitial profiles are imposed across a rectangular simulation cell. The validity\nof this new generalized expression is finally validated using as benchamrk\nsystem a two-component Lennard-Jones liquid system, for which generalized\ndiffusivities are estimated in different reduced temperature and density region\nof phase diagram."
    },
    {
        "anchor": "The Einsteinian T(3)-Gauge Approach and the Stress Tensor of the Screw\n  Dislocation in the Second Order: Avoiding the Cut-off at the Core: A translational gauge approach of the Einstein type is proposed for obtaining\nthe stresses that are due to non-singular screw dislocation. The stress\ndistribution of second order around the screw dislocation is classically known\nfor the hollow circular cylinder with traction-free external and internal\nboundaries. The inner boundary surrounds the dislocation's core, which is not\ncaptured by the conventional solution. The present gauge approach enables us to\ncontinue the classically known quadratic stresses inside the core. The gauge\nequation is chosen in the Hilbert--Einstein form, and it plays the role of\nnon-conventional incompatibility law. The stress function method is used, and\nit leads to the modified stress potential given by two constituents: the\nconventional one, say, the `background' and a short-ranged gauge contribution.\nThe latter just causes additional stresses, which are localized. The asymptotic\nproperties of the resulting stresses are studied. Since the gauge contributions\nare short-ranged, the background stress field dominates sufficiently far from\nthe core. The outer cylinder's boundary is traction-free. At sufficiently\nmoderate distances, the second order stresses acquire regular continuation\nwithin the core region, and the cut-off at the core does not occur. Expressions\nfor the asymptotically far stresses provide self-consistently new length scales\ndependent on the elastic parameters. These lengths could characterize an\nexteriority of the dislocation core region.",
        "positive": "Field Effect Magnetization Reversal in Ferromagnetic Semiconductor\n  Quantum Wells: We predict that a novel bias-voltage assisted magnetization reversal process\nwill occur in Mn doped II-VI semiconductor quantum wells or heterojunctions\nwith carrier induced ferromagnetism. The effect is due to strong\nexchange-coupling induced subband mixing that leads to electrically tunable\nhysteresis loops. Our model calculations are based on the mean-field theory of\ncarrier induced ferromagnetism in Mn-doped quantum wells and on a\nsemi-phenomenological description of the host II-VI semiconductor valence\nbands."
    },
    {
        "anchor": "Dzyaloshinskii-Moriya Interaction-Induced Magnetoelectric Coupling in a\n  tetrahedral Molecular Spin-Frustrated System: We have investigated magnetoelectric coupling in the single-molecule magnet\n$\\mathrm{Mn}_{4}\\mathrm{Te}_{4}(\\mathrm{P}\\mathrm{Et}_{3})_{4}$ with\ntetrahedral spin frustration. Our density functional studies found that an\nelectric dipole moment can emerge with various non-collinear spin orderings.\nThe forms of spin-dependent dipole are determined and consistent with that in\nnon-centrosymmetric magnets driven by the Dzyaloshinskii-Moriya interaction.\nWriting a parameterized spin Hamiltonian, after solving for eigenvalues and\neigenstates we quantified the magnetoelectric coupling by calculating the\nthermal average of the electric and magnetic susceptibilities, which can be\ninfluenced by external magnetic and electric fields, respectively. The\nquadratic relations are expected to be observable in experiments.",
        "positive": "Stabilization of NbTe3, VTe3, and TiTe3 via Nanotube Encapsulation: The structure of MX3 transition metal trichalcogenides (TMTs, with M a\ntransition metal and X a chalcogen) is typified by one-dimensional (1D) chains\nweakly bound together via van der Waals interactions. This structural motif is\ncommon across a range of M and X atoms (e.g. NbSe3, HfTe3, TaS3), but not all M\nand X combinations are stable. We report here that three new members of the MX3\nfamily which are not stable in bulk, specifically NbTe3, VTe3, and TiTe3, can\nbe synthesized in the few- to single-chain limit via nano-confined growth\nwithin the stabilizing cavity of multi-walled carbon nanotubes. Transmission\nelectron microscopy (TEM) and atomic-resolution scanning transmission electron\nmicroscopy (STEM) reveal the chain-like nature and the detailed atomic\nstructure. The synthesized materials exhibit behavior unique to few-chain\nquasi-1D structures, such as multi-chain spiraling and a trigonal\nanti-prismatic rocking distortion in the single-chain limit. Density functional\ntheory (DFT) calculations provide insight into the crystal structure and\nstability of the materials, as well as their electronic structure."
    },
    {
        "anchor": "Half-metallic Dirac cone in zigzag-graphene-nanoribbon/graphene: The Dirac electrons of graphene, an intrinsic zero gap semiconductor,\nuniquely carry spin and pseudospin that give rise to many fascinating\nelectronic and transport properties. While isolated zigzag graphene nanoribbons\nare antiferromagnetic semiconductors, we show by means of first-principles and\ntight-binding calculations that zigzag graphene nanoribbons supported on\ngraphene are half-metallic as a result of spin- and pseudospin-symmetry\nbreaking. In particular, half-metallic Dirac cones are formed at K (K') near\nthe Fermi level. The present results demonstrate that the unique combination of\nspin and pseudospin in zigzag graphene nanoribbons may be used to manipulate\nthe electronic properties of graphene, and may have practical implications for\npotential graphene-based nanoelectronic applications.",
        "positive": "Simultaneous Bright- and Dark-Field X-ray Microscopy at X-ray Free\n  Electron Lasers: The structures, strain fields, and defect distributions in solid materials\nunderlie the mechanical and physical properties across numerous applications.\nMany modern microstructural microscopy tools characterize crystal grains,\ndomains and defects required to map lattice distortions or deformation, but are\nlimited to studies of the (near) surface. Generally speaking, such tools cannot\nprobe the structural dynamics in a way that is representative of bulk behavior.\nSynchrotron X-ray diffraction based imaging has long mapped the deeply embedded\nstructural elements, and with enhanced resolution, Dark Field X-ray Microscopy\n(DFXM) can now map those features with the requisite nm-resolution. However,\nthese techniques still suffer from the required integration times due to\nlimitations from the source and optics. This work extends DFXM to X-ray free\nelectron lasers, showing how the $10^{12}$ photons per pulse available at these\nsources offer structural characterization down to 100 fs resolution (orders of\nmagnitude faster than current synchrotron images). We introduce the XFEL DFXM\nsetup with simultaneous bright field microscopy to probe density changes within\nthe same volume. This work presents a comprehensive guide to the multi-modal\nultrafast high-resolution X-ray microscope that we constructed and tested at\ntwo XFELs, and shows initial data demonstrating two timing strategies to study\nassociated reversible or irreversible lattice dynamics."
    },
    {
        "anchor": "Evolution of the domain topology in a ferroelectric: Topological materials, including topological insulators, magnets with\nSkyrmions and ferroelectrics with topological vortices, have recently attracted\nphenomenal attention in the materials science community. Complex patterns of\nferroelectric domains in hexagonal REMnO3 (RE: rare earths) turn out to be\nassociated with the macroscopic emergence of Z2xZ3 symmetry. The results of our\ndepth profiling of crystals with a self-poling tendency near surfaces reveal\nthat the partial dislocation (i.e., wall-wall) interaction, not the interaction\nbetween vortices and antivortices, is primarily responsible for topological\ncondensation through the macroscopic breaking of the Z2-symmetry.",
        "positive": "Engineering strong magnetoelectricity using a hexagonal 2D material on\n  electron-doped hexagonal LuFeO$_3$: Cubic perovskite-structure ABO$_3$ and A$_{1-x}$A$^{\\prime}$$_x$BO$_3$-type\noxides have been investigated extensively while their hexagonal-structure\nversions have received minimal attention, even though they are multiferroic and\ncan form heterostructures with the manifold hexagonal two-dimensional\nmaterials. Hexagonal ferrites of the form RFeO$_3$, where R is yttrium or a\nrare-earth element such as Lu, Yb, etc., feature coupled ferroelectricity (FE)\nand weak-ferromagnetism (wFM), exhibiting linear magnetoelectricity. Their only\ndrawback is weak ferromagnetism. In this paper, we employ\ndensity-functional-theory (DFT) calculations on hexagonal LuFeO$_3$ ($h$-LFO),\ntargeting its magnetic ordering by electron doping,anticipating\nspin-disproportionation of the Fe sublattices. Indeed, we show that\nspin-disproportionation in heavily-electron-doped versions\nLu$_{1-x}$Hf$_x$FeO$_3$ ($h$-LHFO), especially for x=1/3 and 1/2, leads to\nrobust out-of-plane collinear ferrimagnetism that is stable at room\ntemperature. Furthermore, the robust ferroelectricity of $h$-LFO persists via a\nJahn-Teller metal-to-insulator transition. Finally, we construct a\n$h$-LHFO/$h$-2D heterostructure, where $h$-2D stands for the FE/FM monolayer\nMnSTe, and demonstrate strong magnetoelectric coupling, namely manipulation of\nmagnetic skyrmions in MnSTe by an external electric field through the $h$-LHFO\npolarization, opening up a new realm for magnetoelectric applications."
    },
    {
        "anchor": "Local Aspects of Hydrogen-Induced Metallization of the\n  ZnO(10$\\mathbf{\\overline{1}}$0) Surface: This study combines surface-sensitive photoemission experiments with density\nfunctional theory (DFT) to give a microscopic description of H\nadsorption-induced modifications of the ZnO(10${\\overline{1}}$0) surface\nelectronic structure. We find a complex adsorption behavior caused by a strong\ncoverage dependence of the H adsorption energies: Initially, O--H bond\nformation is energetically favorable and H acting as an electron donor leads to\nthe formation of a charge accumulation layer and to surface metallization. The\nincrease of the number of O--H bonds leads to a reversal in adsorption energies\nsuch that Zn--H bonds become favored at sites close to existing O--H bonds,\nwhich results in a gradual extenuation of the metallization. The corresponding\nsurface potential changes are localized within a few nanometers both laterally\nand normal to the surface. This localized character is experimentally\ncorroborated by using sub-surface bound excitons at the\nZnO(10${\\overline{1}}$0) surface as a local probe. The pronounced and\ncomparably localized effect of small amounts of hydrogen at this surface\nstrongly suggests metallic character of ZnO surfaces under technologically\nrelevant conditions and may, thus, be of high importance for energy level\nalignment at ZnO-based junctions in general.",
        "positive": "A Universal Criterion of Melting: Melting is analyzed dynamically as a problem of localization at a\nliquid-solid interface. A Lindemann-like criterion of melting is derived in\nterms of particular vibrational amplitudes, which turn out to equal a universal\nquotient (about one-tenth) of the molecular spacing, at the interface. The near\nuniversality of the Lindemann ratio apparently arises owing to strongly\noverdamped dynamics near melting, and despite the anharmonic interactions'\nbeing system-specific. A similar criterion is derived for structural\ndisplacements in the bulk of the {\\em solid}, in particular the premelted\nlayer; the criterion is no longer strictly universal, but still depends only on\nthe harmonic properties of the solid. We further compute the dependence of the\nmagnitude of the elemental molecular translations, in deeply supercooled\nfluids, on the temperature and the high frequency elastic constants. We show\nexplicitly that the surface tension between distinct liquid states, near the\nglass transition of a supercooled liquid, is nearly evenly split between\nentropic and energetic contributions."
    },
    {
        "anchor": "Structures of Cylindrical Ultrathin Copper Nanowires: To investigate cylindrical ultrathin copper nanowires, we performed atomistic\nsimulations using the steepest descent method. The stable structures of the\ncylindrical ultrathin copper nanowires were multi-shell packs composed of\ncoaxial cylindrical shells with {111}-like surfaces. Semiclassical orbits in a\ncircle and circular rolling of a triangular network could explain the\nstructures of the cylindrical ultrathin multi-shell copper nanowires. A\ncalculation of the angular correlation function and the radial distribution\nfunction for nanowires showed that the structural properties of nanowires\nbecame closer to those of the bulk with increasing nanowire diameter.",
        "positive": "Laser induced ultrafast demagnetization: an \\emph{ab-initio} perspective: Time-dependent density functional theory is implemented in an all electron\nsolid-state code for the case of fully non-collinear spins. We use this to\nstudy laser induced demagnetization in Fe, Co and Ni. It is shown that this\ndemagnetization is a two-step process: excitation of a fraction of electrons\nfollowed by spin-flip transitions of the remaining localized electrons. These\nresults successfully explain several experimental features such as the time-lag\nbetween the start of the pulse and demagnetization and spin-flip excitations\ndominating the physics. We further show that it is possible to control the\nmoment loss by tunable laser parameters like frequency, duration and intensity."
    },
    {
        "anchor": "From Prediction to Action: Critical Role of Performance Estimation for\n  Machine-Learning-Driven Materials Discovery: Materials discovery driven by statistical property models is an iterative\ndecision process, during which an initial data collection is extended with new\ndata proposed by a model-informed acquisition function--with the goal to\nmaximize a certain \"reward\" over time, such as the maximum property value\ndiscovered so far. While the materials science community achieved much progress\nin developing property models that predict well on average with respect to the\ntraining distribution, this form of in-distribution performance measurement is\nnot directly coupled with the discovery reward. This is because an iterative\ndiscovery process has a shifting reward distribution that is\nover-proportionally determined by the model performance for exceptional\nmaterials. We demonstrate this problem using the example of bulk modulus\nmaximization among double perovskite oxides. We find that the in-distribution\npredictive performance suggests random forests as superior to Gaussian process\nregression, while the results are inverse in terms of the discovery rewards. We\nargue that the lack of proper performance estimation methods from pre-computed\ndata collections is a fundamental problem for improving data-driven materials\ndiscovery, and we propose a novel such estimator that, in contrast to na\\\"ive\nreward estimation, successfully predicts Gaussian processes with the \"expected\nimprovement\" acquisition function as the best out of four options in our\ndemonstrational study for double perovskites. Importantly, it does so without\nrequiring the over thousand ab initio computations that were needed to confirm\nthis prediction.",
        "positive": "A generic method for modelling the behavior of anisotropic metallic\n  materials : application to recrystallized zirconium alloys: A simplified polycrystalline model (the so-called RL model) is proposed to\nsimulate the anisotropic viscoplastic behavior of metallic materials. A generic\nmethod is presented that makes it possible to build a simplified anisotropic\nmaterial texture, based on the principal features of the pole figures. The\nmethod is applied to a recrystallized zirconium alloy, used as clad material in\nthe fuel rods of nuclear power plants. An important database consisting in\nmechanical tests performed on Zircaloy tubes is collected. Only a small number\nof tests (pure tension, pure shear) are used to identify the material\nparameters, and the texture parameters. It is shown that six crystallographic\norientations (6 \"grains\") are sufficient to describe the large anisotropy of\nsuch hcp alloy. The identified crystallographic orientations match the\nexperimental pole figures of the material, not used in the identification\nprocedure. Special attention is paid to the predictive ability of the model,\ni.e., its ability to simulate correctly experimental tests not belonging to the\nidentification database. These predictive results are good, thanks to an\nidentification procedure that enables to consider the contribution of each slip\nsystem in each crystallographic orientation."
    },
    {
        "anchor": "Radial elasticity of multi-walled carbon nanotubes: We report an experimental and a theoretical study of the radial elasticity of\nmulti-walled carbon nanotubes as a function of external radius. We use atomic\nforce microscopy and apply small indentation amplitudes in order to stay in the\nlinear elasticity regime. The number of layers for a given tube radius is\ninferred from transmission electron microscopy, revealing constant ratios of\nexternal to internal radii. This enables a comparison with molecular dynamics\nresults, which also shed some light onto the applicability of Hertz theory in\nthis context. Using this theory, we find a radial Young modulus strongly\ndecreasing with increasing radius and reaching an asymptotic value of 30 +/- 10\nGPa.",
        "positive": "Improved Performance of Organic Light-Emitting Transistors Enabled by\n  Polyurethane Gate Dielectric: Organic light-emitting transistors (OLETs) are multifunctional optoelectronic\ndevices that combine in a single structure the advantages of organic light\nemitting diodes (OLEDs) and organic field-effect transistors (OFETs). However,\nlow charge mobility and high threshold voltage are critical hurdles to\npractical OLETs implementation. This work reports on the improvements obtained\nby using polyurethane films as dielectric layer material in place of the\nstandard poly(methylmethacrylate) (PMMA) in OLET devices. It was found that\npolyurethane drastically reduces the number of traps in the device thereby\nimproving electrical and optoelectronic device parameters. In addition, a model\nwas developed to rationalize an anomalous behavior at the pinch-off voltage.\nOur findings represent a step forward to overcome the limiting factors of OLETs\nthat prevent their use in commercial electronics by providing a simple route\nfor low-bias device operation."
    },
    {
        "anchor": "High-temperature spin-wave propagation in BiFeO3: relation to the\n  Polomska transition: In bismuth ferrite thin films the cycloidal spiral spin structure is\nsuppressed, and as a result the spin-wave magnon branches of long wavelength\nare reduced from a dozen to one, at \\omega = 19.2 cm-1 (T=4K). This spin wave\nhas not been measured previously above room temperature, but in the present\nwork we show via Raman spectroscopy that it is an underdamped propagating wave\nuntil 455 K. This has important room-temperature device implications. The data\nshow that \\omega(T) follows an S=5/2 Brillouin function and hence its Fe+3 ions\nare in the high-spin 5/2 state and not the low-spin S=1/2 state. The spin wave\ncannot be measured as a propagating wave above 455 K. We also suggest that\nsince this temperature is coincident with the mysterious \"Polomska transition\"\n(M. Polomska et al., Phys. Stat. Sol. A 23, 567, (1974)) at 458+/-5 K, that\nthis may be due to overdamping.",
        "positive": "Fast Intercalation of Lithium in Semi-Metallic \u03b3-GeSe Nanosheet:\n  A New Group-IV Monochalcogenide for Lithium-Ion Battery Application: Existence of van der Waals gaps renders two-dimensional (2D) materials ideal\npassages of lithium for being used as anode materials. However, the requirement\nof good conductivity significantly limits the choice of 2D candidates. So far\nonly graphite is satisfying due to its relatively high conductivity. Recently,\na new polymorph of layered germanium selenide (Gamma-GeSe) was proven to be\nsemimetal in its bulk phase with a higher conductivity than graphite while its\nmonolayer behaves semiconducting. In this work, by using first-principles\ncalculations, we examined the possibility of using this new group-IV\nmonochalcogenide, Gamma-GeSe, as anode in the Li-ion battery (LIBs). Our\nstudies revealed that Li atom would form an ionic adsorption with adjacent\nselenium atoms at the hollow site and exist in cationic state (lost 0.89 e to\nGamma-GeSe). Results of climbing image-nudged elastic band show the diffusion\nbarrier of Li is 0.21 eV in the monolayer limit, which can activate a\nrelatively fast diffusion even at room temperature on the Gamma-GeSe surface.\nThe calculated theoretical average voltages range from 0.071 to 0.015 V at\ndifferent stoichiometry of LixGeSe with minor volume variation, suggesting its\npotential application as anode of LIBs. The predicted moderate binding energy,\na low open circuit voltage (comparable to graphite) and a fast motion of Li\nsuggests that Gamma-GeSe nanosheet can be chemically exfoliated via Li\nintercalation and a promising candidate as the anode material for LIBs."
    },
    {
        "anchor": "Converting normal insulators into topological insulators via tuning\n  orbital levels: Tuning the spin-orbit coupling strength via foreign element doping and/or\nmodifying bonding strength via strain engineering are the major routes to\nconvert normal insulators to topological insulators. We here propose an\nalternative strategy to realize topological phase transition by tuning the\norbital level. Following this strategy, our first-principles calculations\ndemonstrate that a topological phase transition in some cubic perovskite-type\ncompounds CsGeBr$_3$ and CsSnBr$_3$ could be facilitated by carbon\nsubstitutional doping. Such unique topological phase transition predominantly\nresults from the lower orbital energy of the carbon dopant, which can pull down\nthe conduction bands and even induce band inversion. Beyond conventional\napproaches, our finding of tuning the orbital level may greatly expand the\nrange of topologically nontrivial materials.",
        "positive": "Adaptive modulations of martensites: Modulated phases occur in numerous functional materials like giant\nferroelectrics and magnetic shape memory alloys. To understand the origin of\nthese phases, we review and generalize the concept of adaptive martensite. As a\nstarting point, we investigate the coexistence of austenite, adaptive 14M phase\nand tetragonal martensite in Ni-Mn-Ga magnetic shape memory alloy epitaxial\nfilms. The modulated martensite can be constructed from nanotwinned variants of\na tetragonal martensite phase. By combining the concept of adaptive martensite\nwith branching of twin variants, we can explain key features of modulated\nphases from a microscopic view. This includes phase stability, the sequence of\n6M-10M-NM intermartensitic transitions, and magnetocrystalline anisotropy."
    },
    {
        "anchor": "Use of real-time Fourier Transform Infrared Reflectivity as an in situ\n  monitor of YBCO film growth and processing: Fourier Transform Infrared (FTIR) spectroscopy has been utilized during high\nrate E-beam evaporation/deposition of YBa2Cu3O7 (YBCO). The results demonstrate\nthe great utility of FTIR as an in situ monitor of YBCO deposition and\nprocessing. We detect different (amorphous/fine polycrystalline) insulating\npre-existing phases to the high Tc superconducting phase which appear to have\ndistinct reflectivity fingerprints dominated by thin film interference effects,\nas a function of temperature and oxygen pressure. These fingerprints reveal\nsome of the kinetic and thermodynamic pathways during the growth of YBCO.",
        "positive": "Electronic Structure of the Ferromagnetic Semiconductor Fe-doped Ge\n  Revealed by Soft X-ray Angle-Resolved Photoemission Spectroscopy: Ge$_{1-x}$Fe$_{x}$ (Ge:Fe) shows ferromagnetic behavior up to a relatively\nhigh temperature of 210 K, and hence is a promising material for spintronic\napplications compatible with Si technology. We have studied its electronic\nstructure by soft x-ray angle-resolved photoemission spectroscopy (SX-ARPES)\nmeasurements in order to elucidate the mechanism of the ferromagnetism. We\nobserved finite Fe 3$d$ components in the states at the Fermi level ($E_{F}$)\nin a wide region in momentum space and $E_{F}$ was located above the\nvalence-band maximum (VBM). First-principles supercell calculation also\nsuggested that the $E_{F}$ is located above the VBM, within the narrow\nspin-down $d$($e$) band and within the spin-up impurity band of the deep\nacceptor-level origin derived from the strong $p$-$d$($t_{2}$) hybridization.\nWe conclude that the narrow $d$($e$) band is responsible for the ferromagnetic\ncoupling between Fe atoms while the acceptor-level-originated band is\nresponsible for the transport properties of Ge:Fe."
    },
    {
        "anchor": "Imposing equilibrium on measured 3-D stress fields using Hodge\n  decomposition and FFT-based optimization: We present a methodology to impose micromechanical constraints, i.e. stress\nequilibrium at grain and sub-grain scale, to an arbitrary (non-equilibrated)\nvoxelized stress field obtained, for example, by means of synchrotron X-ray\ndiffraction techniques. The method consists in finding the equilibrated stress\nfield closest (in $L^2$-norm sense) to the measured non-equilibrated stress\nfield, via the solution of an optimization problem. The extraction of the\ndivergence-free (equilibrated) part of a general (non-equilibrated) field is\nperformed using the Hodge decomposition of a symmetric matrix field, which is\nthe generalization of the Helmholtz decomposition of a vector field into the\nsum of an irrotational field and a solenoidal field. The combination of: a) the\nEuler-Lagrange equations that solve the optimization problem, and b) the Hodge\ndecomposition, gives a differential expression that contains the bi-harmonic\noperator and two times the curl operator acting on the measured stress field.\nThese high-order derivatives can be efficiently performed in Fourier space. The\nmethod is applied to filter the non-equilibrated parts of a synthetic piecewise\nconstant stress fields with a known ground truth, and stress fields in Gum\nMetal, a beta-Ti-based alloy measured in-situ using Diffraction Contrast\nTomography (DCT). In both cases, the largest corrections were obtained near\ngrain boundaries.",
        "positive": "Prediction of stable insulating intermetallic compounds: We explore the stability of structure exhibiting hybridization gaps across a\nbroad range of binary and ternary intermetallic compositions by means of band\nstructure and total energy calculations. This search reveals previously unknown\nmetal-based insulators, some with large gaps exceeding 1 eV, such as Al2Fe and\nAl4IrRe. We confirm large gaps using a hybrid density functional including\nexact exchange, and predict a gap of 2.2 eV for AlMnSi in the Pearson type tP6\nstructure, which is a chemically ordered ternary variant of the prototype MoSi2\n(Pearson type tI6) structure."
    },
    {
        "anchor": "Topological Control on Atomic Networks' Relaxation Under Stress: Upon loading, atomic networks can feature delayed viscoplastic relaxation.\nHowever, the effect of composition and structure on such a relaxation remains\npoorly understood. Herein, relying on accelerated molecular dynamics\nsimulations and topological constraint theory, we investigate the relationship\nbetween atomic topology and stress-induced relaxation, by taking the example of\ncreep deformations in calcium--silicate--hydrates, the binding phase of\nconcrete. Under constant shear stress, C--S--H is found to feature delayed\nlogarithmic shear deformations. We demonstrate that the propensity for\nrelaxation is minimum for isostatic atomic networks, which are characterized by\nthe simultaneous absence of floppy internal modes of relaxation and eigen\nstress. This suggests that topological nano-engineering could lead to the\ndiscovery of non-aging materials.",
        "positive": "Anisotropic ultrafast electron dynamics induced by high-field terahertz\n  pulses in n-doped InGaAs: The anisotropic effective mass of electrons is directly measured using\ntime-resolved THz- pump/THz-probe techniques in a n-doped InGaAs semiconductor\nthin film. A microscopic theory is used to attribute this anisotropy in the THz\nprobe transmission to the nonparabolicity of the conduction band.\nSelf-consistent light-matter coupling is shown to contribute significantly to\nthe THz response."
    },
    {
        "anchor": "On the use of DMT approximations in adhesive contacts, with remarks on\n  random rough contacts: The contact between rough surfaces with adhesion is an extremely difficult\nproblem, and the approximation of the DMT theory (to neglect deformations due\nto attractive forces), originally developed for spherical contact of very small\nradius, are receiving some new interest. The DMT approximation leads to\nextremely large overestimate of the adhesive forces in the case of spherical\ncontact, except at pull-off. For cylindrical contact, the opposite trend is\nfound for larger contact areas. These findings suggest some caution in solving\nrough contacts with DMT models, unless the Tabor parameter is really low.\nFurther approximate models like that of Pastewka & Robbins' may be explained to\nwork only for a coincidence of error cancellation in their range of parameters.",
        "positive": "The structural stability and polarization analysis of rhombohedral phase\n  HfO2: A comparative theoretical study is presented for the rhombohedral R3 and R3m\nphase HfO2, of two possible forms in its heavily Zr-doped ferroelectric thin\nfilms found recently in experiments. Their structural stability and\npolarization under the in-plane compressive strain are comprehensively\ninvestigated. We discovered that there is a phase transition from R3 to R3m\nphase under the biaxial compressive strain. Both the direction and amplitude of\ntheir polarization can be tuned by the strain. By performing a symmetry mode\nanalysis, we are able to understand its improper nature of the\nferroelectricity. These results may help to shed light on the understanding of\nthe hafnia ferroelectric thin films."
    },
    {
        "anchor": "Flexible and biocompatible microelectrode arrays fabricated by\n  supersonic cluster beam deposition on SU-8: We fabricated highly adherent and electrically conductive micropatterns on\nSU-8 by supersonic cluster beam deposition (SCBD). This technique is based on\nthe acceleration of neutral metallic nanoparticles produced in the gas phase.\nThe kinetic energy acquired by the nanoparticles allows implantation in a SU-8\nlayer, thus producing a metal-polymer nanocomposite thin layer. The\nnanocomposite shows ohmic electrical conduction and it can also be used as an\nadhesion layer for further metallization with a metallic overlayer. We\ncharacterized the electrical conduction, adhesion and biocompatibility of\nmicrodevices obtained by SCBD on SU-8 demonstrating the compatibility of our\napproach with standard lift off technology on 4\" wafer. A self-standing and\nflexible Micro Electrode Array has been produced. Cytological tests with\nneuronal cell lines demonstrated an improved cell growth and a spontaneous\nconfinement of cells on the nanocomposite layer.",
        "positive": "Three-Dimensional Topological Insulators in I-III-VI$_2$ and II-IV-V$_2$\n  Chalcopyrite Semiconductors: The recent discovery of topological insulators with exotic metallic surface\nstates has garnered great interest in the fields of condensed matter physics\nand materials science. A number of spectacular quantum phenomena have been\npredicted when the surface states are under the influence of magnetism and\nsuperconductivity, which could open up new opportunities for technological\napplications in spintronics and quantum computing. To achieve this goal,\nmaterial realization of topological insulators with desired physical properties\nis of crucial importance. Based on first-principles calculations, here we show\nthat a large number of ternary chalcopyrite compounds of composition\nI-III-VI$_2$ and II-IV-V$_2$ can realize the topological insulating phase in\ntheir native states. The crystal structure of chalcopyrites is derived from the\nfrequently used zinc-blende structure, and many of them possess a close lattice\nmatch to important mainstream semiconductors, which is essential for a smooth\nintegration into current semiconductor technology. The diverse optical,\nelectrical and structural properties of chalcopyrite semiconductors, and\nparticularly their ability to host room-temperature ferromagnetism, make them\nappealing candidates for novel spintronic devices."
    },
    {
        "anchor": "Magnetic properties of Quantum Corrals from first principles\n  calculations: We present calculations for electronic and magnetic properties of surface\nstates confined by a circular quantum corral built of magnetic adatoms (Fe) on\na Cu(111) surface. We show the oscillations of charge and magnetization\ndensities within the corral and the possibility of the appearance of\nspin--polarized states. In order to classify the peaks in the calculated\ndensity of states with orbital quantum numbers we analyzed the problem in terms\nof a simple quantum mechanical circular well model. This model is also used to\nestimate the behaviour of the magnetization and energy with respect to the\nradius of the circular corral. The calculations are performed fully\nrelativistically using the embedding technique within the\nKorringa-Kohn-Rostoker method.",
        "positive": "Positron Induced Electron Emission from Graphite: In this paper, we present and analyze measurements of the positron induced\nelectron spectra (PIES) from highly oriented pyrolytic graphite (HOPG). The\nspectra were obtained using a time of flight spectrometer attached to a\nvariable energy positron beam. In the first measurements presented, the system\nwas configured to obtain high resolution data from the annihilation induced KVV\nAuger transition of carbon. In the second set of data presented, PIES spectra\nwere obtained for 3 different positron beam energies (1.25 eV, 3.5 eV and 4.5\neV). The resulting time of flight (ToF)-PIES exhibit contributions arising from\neither positron annihilation induced Auger processes (PAES), Auger mediated\npositron sticking (AMPS), or secondary electron emission. Our analysis\nindicates that for incident positron energies 3.5 eV and less, the ToF-PIES can\nbe accounted for considering only two mechanisms: positron annihilation induced\nAuger processes or positron sticking."
    },
    {
        "anchor": "Lattice Expansion of (Ga,Mn)As: The Role of Substitutional Mn and of the\n  Compensating Defects: We apply the density-functional technique to determine the lattice constant\nof GaAs supercells containing Mn_Ga, Mn_int, and As_Ga impurities, and use a\nlinear interpolation to describe the dependence of the lattice constant a of\nGa_{1-x}Mn_xAs on the concentrations of these impurities. The results of the\nsupercell calculations confirm that Mn_Ga does not contribute to the lattice\nexpansion. The increase of a is due to both Mn_int and As_Ga, that are both\ncreated in the as-grown (Ga,Mn)As in proportion to x, and that are most\nprobably present in a remarkable amount also in the best annealed materials.",
        "positive": "Structure refinement from 'Digital' Large Angle Convergent Beam Electron\n  Diffraction Patterns: We use semi-automated data acquisition and processing to produce digital\nlarge angle CBED (D-LACBED) patterns. We demonstrate refinements of atomic\ncoordinates and isotropic Debye-Waller factors for well-known materials using\nsimulations produced with a neutral, spherical independent atom model. We find\nthat atomic coordinate refinements in Al2O3 have sub-pm precision and accuracy.\nIsotropic DWFs are accurate for Cu, a simple fcc metal, but do not agree with\nX-ray measurements of GaAs or Al2O3. This indicates that models of bonding will\nbe essential to fully interpret D-LACBED data."
    },
    {
        "anchor": "Band gap control via tuning of inversion degree in CdIn$_2$S$_4$ spinel: Based on theoretical arguments we propose a possible route for controlling\nthe band-gap in the promising photovoltaic material CdIn$_2$S$_4$. Our\n\\textit{ab initio} calculations show that the experimental degree of inversion\nin this spinel (fraction of tetrahedral sites occupied by In) corresponds\napproximately to the equilibrium value given by the minimum of the theoretical\ninversion free energy at a typical synthesis temperature. Modification of this\ntemperature, or of the cooling rate after synthesis, is then expected to change\nthe inversion degree, which in turn sensitively tunes the electronic band-gap\nof the solid, as shown here by accurate screened hybrid functional\ncalculations.",
        "positive": "Excitation Mechanisms of Er Optical Centers in GaN Epilayers: We report direct evidence of two mechanisms responsible for the excitation of\noptically active Er3+ ions in GaN epilayers grown by metal-organic chemical\nvapor deposition. These mechanisms, resonant excitation via the higher-lying\ninner 4f shell transitions and band-to-band excitation of the semiconductor\nhost, lead to narrow emission lines from isolated and the defect-related Er\ncenters. However, these centers have different photoluminescence spectra, decay\ndynamics, and excitation cross sections. The isolated Er optical center, which\ncan be excited by either mechanism, has the same decay dynamics, but possesses\na much higher cross-section under band-to-band excitation. In contrast, the\ndefect-related Er center can only be excited through band-to-band excitation\nbut has the largest cross-section. These results explain the difficulty in\nachieving gain in Er doped GaN and indicate new approaches for realization of\noptical amplification, and possibly lasing, at room temperature."
    },
    {
        "anchor": "Growth-sequence-dependent interface magnetism of SrIrO$_3$ -\n  La$_{0.7}$Sr$_{0.3}$MnO$_3$ bilayers: Bilayers of the oxide 3d ferromagnet La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ (LSMO) and\nthe 5d paramagnet SrIrO$_{3}$ (SIO) with large spin-orbit coupling (SOC) have\nbeen investigated regarding the impact of interfacial SOC on magnetic order.\nFor the growth sequence of LSMO on SIO, ferromagnetism is strongly altered and\nlarge out-of-plane-canted anisotropy associated with lacking magnetic\nsaturation up to 4 T has been observed. Thin bilayer films have been grown\ncoherently in both growth sequences on SrTiO$_3$ (001) by pulsed laser\ndeposition and structurally characterized by scanning transmission electron\nmicroscopy (STEM) and x-ray diffraction (XRD). Measurements of magnetization\nand field-dependent Mn L$_{2,3}$ edge x-ray magnetic circular dichroism (XMCD)\nreveal changes of LSMO magnetic order which are strong in LSMO on SIO and weak\nin LSMO underneath of SIO. We attribute the impact of the growth sequence to\nthe interfacial lattice structure/symmetry which is known to influence the\ninterfacial magnetic coupling.",
        "positive": "Dual-channel charge transfer doping of graphene by sulfuric acid: Two-dimensional materials represented by graphene and transition metal\ndichalcogenides undergo charge transfer (CT) processes and become hole-doped in\nstrong mineral acids. Nonetheless, their mechanisms remain unclear or\ncontroversial. This work proposes and verifies two distinctive CT channels in\nsulfuric acids, respectively driven by oxygen reduction reaction involving\nO2/H2O redox couples and reduction of bisulfate or related species.\nAcid-induced changes in the charge density of graphene were in-situ quantified\nas a function of oxygen content using Raman spectroscopy. At acid\nconcentrations lower than 6 M, the former channel is operative, requiring\ndissolved O2. Above 6 M, the degree of CT was even higher because the former is\ncooperated with by the latter channel, which does not need dissolved oxygen.\nThe mechanism revealed in this study will advance our fundamental understanding\nof how low-dimensional materials interact with chemical environments."
    },
    {
        "anchor": "High Curie temperature and high hole mobility in diluted magnetic\n  semiconductors (B, Mn)X (X = N, P, As, Sb): Doping nonmagnetic semiconductors with magnetic impurities is a feasible way\nto obtain diluted magnetic semiconductors (DMSs). It is generally accepted that\nfor the most extensively studied DMS, (Ga, Mn)As, its highest Curie temperature\nT$_{\\text{C}}$ was achieved at 200 K with a Mn concentration of approximately\n16% in experiments. A recent experiment reported record-breaking high electron\nand hole mobilities in the semiconductor BAs [Science 377, 437 (2022)]. Since\nBAs shares the same zinc-blende structure with GaAs, here we predict four DMSs\n(B, Mn)X (X = N, P, As, Sb) by density functional theory calculations. Our\nresults indicate that a significantly higher T$_{\\text{C}}$ in the range of 254\nK to 300 K for (B, Mn)As with a Mn concentration of around 15.6%, and even\nhigher T$_{\\text{C}}$ values above the room temperature for (B, Mn)N and (B,\nMn)P with a Mn concentration exceeding 12.5%. Furthermore, we have predicted a\nlarge hole mobility of 1561 cm$^{\\text{2}}$V$^{\\text{-1}}$s$^{\\text{-1}}$ at\n300 K for (B, Mn)As with a Mn concentration of about 3.7%, which is three\norders of magnitude larger than the hole mobility of 4\ncm$^{\\text{2}}$V$^{\\text{-1}}$s$^{\\text{-1}}$ at 300 K observed in the\nexperiment for (Ga, Mn)As. Our findings predict the emergence of a new family\nof DMS, (B, Mn)X, and are expected to stimulate both experimental and\ntheoretical studies of the DMS with high T$_{\\text{C}}$ and high mobilities.",
        "positive": "Monolayer MoS$_2$ Strained to 1.3\\% with a Microelectromechanical System: We report on a modified transfer technique for atomically thin materials\nintegrated onto microelectromechanical systems (MEMS) for studying strain\nphysics and creating strain-based devices. Our method tolerates the non-planar\nstructures and fragility of MEMS, while still providing precise positioning and\ncrack free transfer of flakes. Further, our method used the transfer polymer to\nanchor the 2D crystal to the MEMS, which reduces the fabrication time,\nincreases the yield, and allowed us to exploit the strong mechanical coupling\nbetween 2D crystal and polymer to strain the atomically thin system. We\nsuccessfully strained single atomic layers of molybdenum disulfide (MoS$_2$)\nwith MEMS devices for the first time and achieved greater than 1.3\\% strain,\nmarking a major milestone for incorporating 2D materials with MEMS We used the\nestablished strain response of MoS$_2$ Raman and Photoluminescence spectra to\ndeduce the strain in our crystals and provide a consistency check. We found\ngood comparison between our experiment and literature."
    },
    {
        "anchor": "Anomalous random correlations of force constants on the lattice\n  dynamical properties of disordered Au-Fe alloys: Au-Fe alloys are of immense interest due to their biocompatibility, anomalous\nhall conductivity, and applications in various medical treatment. However,\nirrespective of the method of preparation, they often exhibit a high-level of\ndisorder, with properties sensitive to the thermal or magnetic annealing\ntemperatures. We calculate lattice dynamical properties of Au$_{1-x}$Fe$_x$\nalloys using density functional theory methods, where, being a multisite\nproperty, reliable interatomic force constant (IFC) calculations in disordered\nalloys remain a challenge. We follow a two fold approach: (1) an accurate IFC\ncalculation in an environment with nominally zero chemical pair correlations to\nmimic the homogeneously disordered alloy; and (2) a configurational averaging\nfor the desired phonon properties (e.g., dispersion, density of states, and\nentropy). We find an anomalous change in the IFC's and phonon dispersion (split\nbands) near $x$=0.19, which is attributed to the local stiffening of the Au-Au\nbonds when Au is in the vicinity of Fe. Other results based on mechanical and\nthermo-physical properties reflect a similar anomaly: Phonon entropy, e.g.,\nbecomes negative below $x$=0.19, suggesting a tendency for chemical unmixing,\nreflecting the onset of miscibility gap in the phase diagram. Our results match\nfairly well with reported data, wherever available.",
        "positive": "Breakthrough in HAXPES Performance Combining Full-Field k-Imaging with\n  Time-of-Flight Recording: We established a new approach to hard-X-ray photoelectron spectroscopy\n(HAXPES). The instrumental key feature is an increase of the dimensionality of\nthe recording scheme from 2D to 3D. A high-energy momentum microscope can\ndetect electrons with initial kinetic energies more than 6 keV with high\nangular resolution < 0.1{\\deg}. The large k-space acceptance of the special\nobjective lens allows for simultaneous full-field imaging of many Brillouin\nzones. Combined with time-of-flight parallel energy recording, this method\nyields maximum parallelization of data acquisition. In a pilot experiment at\nthe new beamline P22 at PETRA III, Hamburg, count rates of more than $10^{6}$\ncounts per second in the d-band complex of transition metals established an\nunprecedented HAXPES recording speed. It was found that the concept of\ntomographic k-space mapping previously demonstrated in the soft X-ray regime\nworks equally well in the hard X-ray range. Sharp valence band k-patterns of Re\ncollected at an excitation energy of 6 keV correspond to direct transitions to\nthe 28th repeated Brillouin zone. Given the high X-ray brilliance\n(1.1x$10^{13}$ hv/s in a spot of less than 20x15 $mu^{2}$), the 3D bulk\nBrillouin zone can be mapped in a few hours. X-ray photoelectron diffraction\n(XPD) patterns with < 0.1{\\deg} resolution are recorded within minutes.\nPreviously unobserved fine details in the diffractograms reflect the large\nnumber of scatterers, several $10^{4}$ to $10^{6}$, depending on energy. The\nshort photoelectron wavelength (an order of magnitude smaller than the\ninteratomic distance) amplifies phase differences and makes hard X-ray XPD with\nhigh resolution a very sensitive structural tool. The high count rates pave the\nway towards spin-resolved HAXPES using an imaging spin filter."
    },
    {
        "anchor": "Chemical vapour deposition synthetic diamond: materials, technology and\n  applications: Substantial developments have been achieved in the synthesis of chemical\nvapour deposition (CVD) diamond in recent years, providing engineers and\ndesigners with access to a large range of new diamond materials. CVD diamond\nhas a number of outstanding material properties that can enable exceptional\nperformance in applications as diverse as medical diagnostics, water treatment,\nradiation detection, high power electronics, consumer audio, magnetometry and\nnovel lasers. Often the material is synthesized in planar form, however\nnon-planar geometries are also possible and enable a number of key\napplications. This article reviews the material properties and characteristics\nof single crystal and polycrystalline CVD diamond, and how these can be\nutilized, focusing particularly on optics, electronics and electrochemistry. It\nalso summarizes how CVD diamond can be tailored for specific applications,\nbased on the ability to synthesize a consistent and engineered high performance\nproduct.",
        "positive": "Full-frequency dynamical Bethe-Salpeter equation without frequency and a\n  study of double excitations: The Bethe-Salpeter equation (BSE) that results from the GW approximation to\nthe self-energy is a frequency-dependent (nonlinear) eigenvalue problem due to\nthe dynamically screened Coulomb interaction between electrons and holes. The\ncomputational time required for a numerically exact treatment of this frequency\ndependence is $O(N^6)$, where $N$ is the system size. To avoid the common\nstatic screening approximation, we show that the full-frequency dynamical BSE\ncan be exactly reformulated as a frequency-independent eigenvalue problem in an\nexpanded space of single and double excitations. When combined with an\niterative eigensolver and the density fitting approximation to the electron\nrepulsion integrals, this reformulation yields a dynamical BSE algorithm whose\ncomputational time is $O(N^5)$, which we verify numerically. Furthermore, the\nreformulation provides direct access to excited states with dominant double\nexcitation character, which are completely absent in the spectrum of the\nstatically screened BSE. We study the $2^1A_\\mathrm{g}$ state of butadiene,\nhexatriene, and octatetraene and find that GW/BSE overestimates the excitation\nenergy by about 1.5-2 eV and significantly underestimates the double excitation\ncharacter."
    },
    {
        "anchor": "Ab initio pseudopotentials for electronic structure calculations of\n  poly-atomic systems using density-functional theory: The package fhi98PP allows one to generate norm-conserving pseudopotentials\nadapted to density-functional theory total-energy calculations for a multitude\nof elements throughout the periodic table, including first-row and transition\nmetal elements. The package also facilitates a first assessment of the\npseudopotentials' transferability, either in semilocal or fully separable form,\nby means of simple tests carried out for the free atom. Various\nparameterizations of the local-density approximation and the generalized\ngradient approximation for exchange and correlation are implemented.",
        "positive": "Experimental observation of anisotropic Adler-Bell-Jackiw anomaly in\n  type-II Weyl semimetal WTe$_{1.98}$ crystals at the quasi-classical regime: The asymmetric electron dispersion in type-II Weyl semimetal theoretically\nhosts anisotropic transport properties. Here we observe the significant\nanisotropic Adler-Bell-Jackiw (ABJ) anomaly in the Fermi-level delicately\nadjusted WTe$_{1.98}$ crystals. Quantitatively, $C_w$ , a coefficient\nrepresenting intensity of ABJ anomaly, along a- and b-axis of WTe$_{1.98}$ are\n0.030 and 0.051 T$^{-2}$ at 2 K, respectively. We found that\ntemperature-sensitive ABJ anomaly is attributed to topological phase transition\nfrom type-II Weyl semimetal to trivial semimetal, which is verified by\nfirst-principles calculation using experimentally determined lattice parameters\nat different temperatures. Theoretical electrical transport study reveals that\nobservation of ansotropic ABJ both along a- and b-axis in WTe$_{1.98}$ is\nattributed to electrical transport in the quasi-classical regime. Our work may\nsuggest that electron-doped WTe$_2$ is an ideal playground to explore the novel\nproperties in type-II Weyl semimetals."
    },
    {
        "anchor": "Parity-breaking in single-element phases: Ferroelectric-like elemental\n  polar metals: Polar metals based on binary and ternary compounds have been demonstrated in\nliterature. Here, we propose a design principle for ferroelectric-like\nelemental polar metals and relate it to real materials. The design principle is\nthat, to be an elemental polar metal, atoms should occupy at least two\ninequivalent Wyckoff positions in a crystal with a polar space group, where\ninversion symmetry is spontaneously broken. According to this rule, we propose\nthe first class of potential ferroelectric-like elemental polar metals in a\ndistorted {\\alpha}-La-like structure with a polar space group P63mc in which\ntwo inequivalent Wyckoff positions 2a (0, 0, z) and 2b (1/3, 2/3, z) are\noccupied by group-V elements (phosphorus, arsenic, antimony, and bismuth).\nAnalyses based on first-principles calculations indicate that the dynamically\nstable polar phase results from a lone pair driven polar distortion of the\nnonploar phase in P63/mmc symmetry where two inequivalent Wyckoff positions 2a\n(0, 0, 0) and 2c (1/3, 2/3, 1/4) are occupied. This ferroelectric-like\ntransition involves a transition from a metallic state to a semimetallic state.\nThese predicted polar phases are metastable with respect to their corresponding\nground phases. Moreover, ionic bonding characters are found due to the\ninequivalence in Wyckoff positions between group-V atoms. Our work opens a\nroute to single-element parity-breaking phases.",
        "positive": "Compensation-dependence of magnetic and electrical properties in\n  Ga1-xMnxP: We demonstrate the control of the hole concentration in Ga1-xMnxP over a wide\nrange by introducing compensating vacancies. The resulting evolution of the\nCurie temperature from 51 K to 7.5 K is remarkably similar to that observed in\nGa1-xMnxAs despite the dramatically different character of hole transport\nbetween the two material systems. The highly localized nature of holes in\nGa1-xMnxP is reflected in the accompanying increase in resistivity by many\norders of magnitude. Based on variable-temperature resistivity data we present\na general picture for hole conduction in which variable-range hopping is the\ndominant transport mechanism in the presence of compensation."
    },
    {
        "anchor": "Hysteretic magnetoresistance in polymeric diodes: We report on hysteretic organic magnetoresistance (OMAR) in polymeric diodes.\nWe found that magnitude and lineshape of OMAR depends strongly on the scan\nspeed of the magnetic field and on the time delay between two successive\nmeasurements. The time-dependent OMAR phenomenon is universal for diodes made\nwith various polymers. However, the width and magnitude of OMAR varied with the\npolymeric material. The suggestive reason for this hysteretic behavior are\ntrapped carriers, which in presence of a magnetic field changes the\nferromagnetic ground-state of the polymer leading to long spin relaxation time.\nThese experimental observations are significant for clarification of the OMAR\nphenomenon.",
        "positive": "Resonant States in the Electronic Structure of the High Performance\n  Thermoelectrics AgPb$_{m}SbTe$_{2+m}$ ; The Role of Ag-Sb Microstructures: Ab initio electronic structure calculations based on gradient corrected\ndensity functional theory were performed on a class of novel quaternary\ncompounds AgPb$_{m}SbTe$_{2+m}$, which were found to be excellent high\ntemperature thermoelctrics with large figure of merit ZT ~2.2 at 800K. We find\nthat resonant states appear near the top of the valence and bottom of the\nconduction bands of bulk PbTe when Ag and Sb replace Pb. These states can be\nunderstood in terms of modified Te-Ag(Sb) bonds. Electronic structure near the\ngap depends sensitively on the microstructural arrangements of Ag-Sb atoms,\nsuggesting that large ZT values may originate from the nature of these ordering\narrangements."
    },
    {
        "anchor": "Strain driven onset of non-trivial topological insulating states in\n  Zintl Sr$_2X$ compounds ($X$=Pb, Sn): We explore the topological behavior of the binary Zintl phase of the alkaline\nearth metals based compounds Sr$_2$Pb and Sr$_2$Sn using both standard and\nhybrid density functional theory. It is found that Sr$_2$Pb lies on the verge\nof a topological instability which can be suitably tuned through the\napplication of a small uniaxial expansion strain ($>$ 3%). The resulting\nnon-trivial topologically insulating state display well-defined metallic states\nin the Sr$_{2}$Pb(010) surface, whose evolution is studied as a function of the\nfilm thickness.",
        "positive": "Simulation Study of Sulfonate Cluster Swelling in Ionomers: We have performed simulations to study how increasing humidity affects the\nstructure of Nafion-like ionomers under conditions of low sulfonate\nconcentration and low humidity. At the onset of membrane hydration, the\nclusters split into smaller parts. These subsequently swell, but then maintain\nconstant the number of sulfonates per cluster. We find that the distribution of\nwater in low-sulfonate membranes depends strongly on the sulfonate\nconcentration. For a relatively low sulfonate concentration, nearly all the\nside-chain terminal groups are within cluster formations, and the average water\nloading per cluster matches the water content of membrane. However, for a\nrelatively higher sulfonate concentration the water-to-sulfonate ratio becomes\nnon-uniform. The clusters become wetter, while the inter-cluster bridges become\ndrier. We note the formation of unusual shells of water-rich material that\nsurround the sulfonate clusters."
    },
    {
        "anchor": "Effective elastic moduli of polymer bonded explosives from finite\n  element simulations: Finite element analysis has been used successfully to estimate the effective\nproperties of many types of composites. The prediction of effective elastic\nmoduli of polymer-bonded explosives provides a new challenge. These particulate\ncomposites contain extremely high volume fractions of explosive particles ($>$\n0.90). At room temperature and higher, the Young's modulus of the particles can\nbe 20,000 times that of the binder. Under these conditions, rigorous bounds and\nanalytical approximations for effective elastic properties predict values that\nare orders of magnitude different from the experimental values. In this work,\nan approach is presented that can be used to predict three-dimensional\neffective elastic moduli from two-dimensional finite element simulations. The\napproach is validated by comparison with differential effective medium\nestimates and three-dimensional finite element simulations.",
        "positive": "Screening and understanding Li adsorption on 2-dimensional metallic\n  materials by learning physics: Two-dimensional (2D) materials have received considerable attention as\npossible electrodes in Li-ion batteries (LIBs), although a deeper understanding\nof the Li adsorption behavior as well as broad screening of the materials space\nis still needed. In this work, we build a high-throughput screening scheme that\nincorporates a learned interaction. First, density functional theory and graph\nconvolution networks are utilized to calculate minimum Li adsorption energies\nfor a small set of 2D metallic materials. The data is then used to find a\ndependence of the minimum Li adsorption energies on the sum of ionization\npotential, work function of the 2D metal, and coupling energy between Li+ and\nsubstrate. Our results show that variances of elemental properties and density\nare the most correlated features with coupling. To illustrate the applicability\nof this approach, the model is employed to show that some fluorides and\nchromium oxides are potential high-voltage materials with adsorption energies <\n-7 eV, and the found physics is used as the design principle to enhance the Li\nadsorption ability of graphene. This physics-driven approach shows higher\naccuracy and transferability compared with purely data-driven models."
    },
    {
        "anchor": "Alloying induces directionally-dependent mobility and alters migration\n  mechanisms of faceted grain boundaries: Faceted grain boundaries exhibit unusual segregation and migration\ntendencies. To gain a deeper understanding of how solute atoms interact with\nfaceted interfacial structures during migration, this study probes the\nmigration behavior of a faceted $\\Sigma$11 boundary in Cu doped with Ag atoms.\nThe solutes are found to segregate to the facet with more free volume and\nstrongly reduce boundary velocity in one migration direction, but not the\nother, due to the presence of a directionally-dependent motion mechanism that\ncan escape solute pinning and therefore speed up migration. Hence, a new\nmechanism of chemically-induced anisotropy in grain boundary mobility is\nuncovered by these simulations.",
        "positive": "A Comparison of Anodic TiO2 Nanotube Membranes used for Front-side\n  Illuminated Dye-Sensitized Solar Cells: In the present work we compare TiO2 nanotube lift-off strategies for the\nconstruction of front-side illuminated dye-sensitized solar cells (DSSCs).\nAnodic nanotube layers were detached from the metallic back contact by using\ndifferent techniques and transferred onto an FTO substrate. We show that if we\nuse an optimized potential step treatment to fabricate membranes, DSSC cell\nefficiencies can be significantly increased (>8%). This improved efficiency is\nascribed to higher specific dye-loading and enhanced electron transport\nproperties of optimally fabricated TiO2 nanotube membranes."
    },
    {
        "anchor": "Iodine intercalation in Bi/Ca/Co/O layered cobaltites: This paper has been withdrawn",
        "positive": "Conductivity states changes in plasticized PVC films near breakdown\n  threshold voltages values: The near threshold \"soft breakdown\" measurements of PVC films conductivity\nare investigated. In a wide range of external electric field strength for\nvarious rather thick (>20 mkm) PVC films the resistance shows strong\nnonlinearity and seems to enter high conductive state close to the breakdown\nthreshold. For our \"thick\" films boundary conditions electrode surface\nspecifics should not be so important as in thin polymer films experiments. Both\nfast, instant mechanisms of nonlinearity, and effects of accumulation and delay\nresponce were observed. The phenomena corresponding to reversible transitions\nin a state with rather high conductivity, seems to be similar to ones\nregistered earlier in thin layers of some broad-bandgap polymers. In a range of\nrelatively low field intensity, far from a threshold breakdown, as a result of\nreversible switches between normal and high resistivity states a polymer film\nin a standard measuring cell formed a relaxation generator giving a loud enough\nsound signal with frequency increasing with the increase of external field."
    },
    {
        "anchor": "Phonon Fingerprints of CsPb2Br5 Single Crystals: CsPb2Br5 is a stable, water-resistant, material derived from CsPbBr3\nperovskite and featuring two-dimensional Pb-Br framework separated by Cs\nlayers. Both compounds can coexist at nano- length scale, which often produces\nconflicting optical spectroscopy results. We present a complete set of\npolarized Raman spectra of nonluminescent CsPb2Br5 single crystals that reveals\nthe symmetry and frequency of nondegenerate Raman active phonons accessible\nfrom the basal (001) plane. The experimental results are in good agreement with\ndensity functional perturbation theory simulations, which suggests that the\ncalculated frequencies of yet unobserved double degenerate Raman and infrared\nphonons are also reliable. Unlike CsPbBr3, the lattice dynamics of CsPb2Br5 is\nstable as evidenced by the calculated phonon dispersion. The sharp Raman lines\nand lack of a dynamic- disorder-induced central peak in the spectra at room\ntemperature indicate that the coupling of Cs anharmonic motion to Br atoms,\nknown to cause the dynamic disorder in CsPbBr3, is absent in CsPb2Br5.",
        "positive": "Controllable patterning and CVD growth of isolated carbon nanotubes with\n  direct parallel writing of catalyst using Dip Pen Nanolithography: We report a process to fabricate carbon nanotubes (CNT) by chemical vapor\ndeposition at predetermined location. This process was enabled by patterning\ncatalyst nanoparticles directly on silicon substrates with nanometer-scale\nprecision using Dip Pen Nanolithography(R) (DPN(R)). A multi-pen writing method\nwas employed to increase the patterning rate. The development of new molecular\ninks for the deposition of the precursor catalyst resulted in a high yield of\nisolated carbon nanotubes, ideal for subsequent device fabrication. Here, we\ndemonstrate the advantages of the new method for producing high quality\nisolated CNT in scalable array geometries."
    },
    {
        "anchor": "Blue light-emitting diode based on ZnO: A near-band-edge bluish electroluminescence (EL) band centered at around 440\nnm was observed from ZnO p-i-n homojunction diodes through a semi-transparent\nelectrode deposited on the p-type ZnO top layer. The EL peak energy coincided\nwith the photoluminescence peak energy of an equivalent p-type ZnO layer,\nindicating that the electron injection from the n-type layer to the p-type\nlayer dominates the current, giving rise to the radiative recombination in the\np-type layer. The imbalance in charge injection is considered to originate from\nthe lower majority carrier concentration in the p-type layer, which is one or\ntwo orders of magnitude lower than that in the n-type one. The current-voltage\ncharacteristics showed the presence of series resistance of several hundreds\nohms, corresponding to the current spread resistance within the bottom n-type\nZnO. The employment of conducting ZnO substrates may solve the latter problem.",
        "positive": "Heteroepitaxy of FCC-on-FCC Systems of Large Misfit: To understand the effects of lattice mismatch on heteroepitaxial growth, we\nhave studied the equilibrium structure and orientation relationships (ORs) of\nFCC films grown epitaxially on FCC substrates, using molecular dynamics\nsimulations in conjunction with embedded atom method potentials. Three\nfilm/substrate systems have been investigated, namely: Ag on Cu, Ag on Ni and\nPb on Al. These systems cover a significant range of lattice mismatch, from\n12.6% for Ag/Cu to 21.8% for Pb/Al. For each system, the ORs of films on six\ndifferent substrate orientations, namely: (100), (511), (311), (211), (322) and\n(111), have been investigated. Films on these susbstrates cover a gradual\ntransition from the oct-cube orientation relationship, which occurs only on\n(100) substrates, to the heterotwin orientation relationship, which often\noccurs on (111) substrates. It is found that the resulting ORs vary\nsystematically with substrate orientation, but that the pattern of variation is\nalmost identical for all three systems, and therefore largely independent of\nmismatch. However, the manner in which mismatch is accommodated does depend on\nthe magnitude of mismatch. Simulations point to an important role for\nedge-to-edge matching and defects such as stacking faults. An analysis of these\nresults in terms of transformation strains highlights the distinction between\nthe ORs, which are largely independent of mismatch, and the local interfacial\nstructure, which changes directly with mismatch."
    },
    {
        "anchor": "Surface Effects on the Piezoelectricity of ZnO Nanowires: We utilize classical molecular dynamics to study surface effects on the\npiezoelectric properties of ZnO nanowires as calculated under uniaxial loading.\nAn important point to our work is that we have utilized two types of surface\ntreatments, those of charge compensation and surface passivation, to eliminate\nthe polarization divergence that otherwise occurs due to the polar (0001)\nsurfaces of ZnO. In doing so, we find that if appropriate surface treatments\nare utilized, the elastic modulus and the piezoelectric properties for ZnO\nnanowires having a variety of axial and surface orientations are all reduced as\ncompared to the bulk value as a result of polarization-reduction in the polar\n[0001] direction. The reduction in effective piezoelectric constant is found to\nbe independent of the expansion or contraction of the polar (0001) surface in\nresponse to surface stresses. Instead, the surface polarization and thus\neffective piezoelectric constant is substantially reduced due to a reduction in\nthe bond length of the Zn-O dimer closest to the polar (0001) surface.\nFurthermore, depending on the nanowire axial orientation, we find in the\nabsence of surface treatment that the piezoelectric properties of ZnO are\neither effectively lost due to unphysical transformations from the wurtzite to\nnon-piezoelectric d-BCT phases, or also become smaller with decreasing nanowire\nsize. The overall implication of this study is that if enhancement of the\npiezoelectric properties of ZnO is desired, then continued miniaturization of\nsquare or nearly square cross section ZnO wires to the nanometer scale is not\nlikely to achieve this result.",
        "positive": "Vitreous silica distends in helium gas: acoustic vs. static\n  compressibilities: Sound velocities of vitreous silica are measured under He compression in the\npressure range 0-6 GPa by Brillouin light scattering. It is found that the\nwell-known anomalous maximum in the pressure dependence of the compressibility\nis suppressed by He incorporation into the silica network. This shows that the\nelastic anomaly relates to the collapse of the largest interstitial voids in\nthe structure. The huge difference between the static and the acoustic\ncompressibilities indicates that the amount of incorporated helium still\nincreases at 6 GPa."
    },
    {
        "anchor": "Tunable Finite-Sized Chains to Control Magnetic Relaxation: The magnetic dynamics of low-dimensional iron ion chains have been studied\nwith regards to the tunable finite-sized chain length using iron phthalocyanine\nthin films. The deposition temperature varies the diffusion length during thin\nfilm growth by limiting the average crystal size in the range from 40 to 110\nnm. Using a method common for single chain magnets, the magnetic relaxation\ntime for each chain length is determined from temporal remanence data and fit\nto a stretched exponential form in the temperature range below 5 K, the onset\nfor magnetic hysteresis. A temperature-independent master curve is generated by\nscaling the remanence by its relaxation time to fit the energy barrier for spin\nreversal, and the single spin relaxation time. The energy barrier of 95 K is\nfound to be independent of the chain length. In contrast, the single spin\nrelaxation time increases with longer chains from under 1 ps to 800 ps. We show\nthat thin films provide the nano-architecture to control magnetic relaxation\nand a testbed to study finite-size effects in low-dimensional magnetic systems.",
        "positive": "Atomic and electronic structure of monolayer graphene on 6H-SiC(000-1)(3\n  x 3) : a scanning tunneling microscopy study: We present an investigation of the atomic and electronic structure of\ngraphene monolayer islands on the 6H-SiC(000-1)(3x3) (SiC(3x3)) surface\nreconstruction using scanning tunneling microscopy (STM) and spectroscopy\n(STS). The orientation of the graphene lattice changes from one island to the\nother. In the STM images, this rotational disorder gives rise to various\nsuperlattices with periods in the nm range. We show that those superlattices\nare moir\\'e patterns (MPs) and we correlate their apparent height with the\nstacking at the graphene/SiC(3x3) interface. The contrast of the MP in STM\nimages corresponds to a small topographic modulation of the graphene layer.\n  From STS measurements we find that the substrate surface presents a 1,5 eV\nwide bandgap encompassing the Fermi level. This substrate surface bandgap\nsubsists below the graphene plane. The tunneling spectra are spatially\nhomogeneous on the islands within the substrate surface gap, which shows that\nthe MPs do not impact the low energy electronic structure of graphene. We\nconclude that the SiC(3 x 3) reconstruction efficiently passivates the\nsubstrate surface and that the properties of the graphene layer which grows on\ntop of it should be similar to those of the ideal material."
    },
    {
        "anchor": "Effect of disorder on the optical response of NiPt and Ni$_3$Pt alloys: In this communication we present a detailed study of the effect of chemical\ndisorder on the optical response of Ni$_{1-x}$Pt$_x$ (0.1$\\leq$ x $\\leq$0.75)\nand Ni$_{3(1-x)/3}$Pt$_x$ (0.1$\\leq$ x $\\leq$0.3). We shall propose a formalism\nwhich will combine a Kubo-Greenwood approach with a DFT based tight-binding\nlinear muffin-tin orbitals (TB-LMTO) basis and augmented space recursion (ASR)\ntechnique to explicitly incorporate the effect of disorder. We show that\nchemical disorder has a large impact on optical response of Ni-Pt systems. In\nordered Ni-Pt alloys, the optical conductivity peaks are sharp. But as we\nswitch on chemical disorder, the UV peak becomes broadened and its position as\na function of composition and disorder carries the signature of a phase\ntransition from NiPt to Ni$_3$Pt with decreasing Pt concentration.\nQuantitatively this agrees well with Massalski's Ni-Pt phase diagram\n\\cite{massal}. Both ordered NiPt and Ni$_3$Pt have an optical conductivity\ntransition at 4.12 eV. But disordered NiPt has an optical conductivity\ntransition at 3.93 eV. If we decrease the Pt content, it results a chemical\nphase transition from NiPt to Ni$_3$Pt and shifts the peak position by 1.67 eV\nto the ultraviolet range at 5.6 eV. There is a significant broadening of UV\npeak with increasing Pt content due to enhancement of 3d(Ni)-5d(Pt) bonding.\nChemical disorder enhances the optical response of NiPt alloys nearly one order\nof magnitude. Our study also shows the fragile magnetic effect on optical\nresponse of disordered Ni$_{1-x}$Pt$_x$ (0.4$<$ x $<$0.6) binary alloys. Our\ntheoretical predictions agree more than reasonably well with both earlier\nexperimental as well as theoretical investigations.",
        "positive": "Crystal structure evolution in the van der Waals transition metal\n  trihalides: Most transition-metal trihalides are dimorphic. The representative\nchromium-based triad, CrCl3, CrBr3, CrI3, is characterized by the\nlow-temperature phase adopting the trigonal BiI3 type while the structure of\nthe high-temperature phase is monoclinic of AlCl3 type (C2/m). The structural\ntransition between the two crystallographic phases is of the first-order type\nwith large thermal hysteresis in CrCl3 and CrI3. We studied crystal structures\nand structural phase transitions of vanadium-based counterparts VCl3, VBr3, and\nVI3 by measuring specific heat, magnetization, and X-ray diffraction as\nfunctions of temperature and observed an inverse situation. In these cases, the\nhigh-temperature phase has a higher symmetry while the low-temperature\nstructure reveals a lower symmetry. The structural phase transition between\nthem shows no measurable hysteresis in contrast to CrX3. Possible relations of\nthe evolution of the ratio c/a of the unit cell parameters, types of crystal\nstructures, and nature of the structural transitions in V and Cr trihalides are\ndiscussed."
    },
    {
        "anchor": "Inversion of ferrimagnetic magnetization by ferroelectric switching via\n  a novel magnetoelectric coupling: Although several multiferroic materials/heterostructures have been\nextensively studied, finding strong magnetoelectric couplings for the electric\nfield control of the magnetization remains challenging. Here, a novel\ninterfacial magnetoelectric coupling based on three components (ferroelectric\ndipole, magnetic moment, and antiferromagnetic order) is analytically\nformulated. As an extension of carrier-mediated magnetoelectricity, the new\ncoupling is shown to induce an electric-magnetic hysteresis loop. Realizations\nemploying BiFeO$_3$ bilayers grown along the [$111$] axis are proposed. Without\ninvolving magnetic phase transitions, the magnetization orientation can be\nswitched by the carrier modulation driven by the field effect, as confirmed\nusing first-principles calculations.",
        "positive": "Isolated highly localized bands in $\\mathrm{YbI_2}$ monolayer caused by\n  $4f$ orbitals: The novel electronic structures can induce unique physical properties in\ntwo-dimensional (2D) materials. In this work, we report isolated highly\nlocalized bands in $\\mathrm{YbI_2}$ monolayer by the first-principle\ncalculations within generalized gradient approximation (GGA) plus spin-orbit\ncoupling (SOC). It is found that $\\mathrm{YbI_2}$ monolayer is an indirect-gap\nsemiconductor using both GGA and GGA+SOC. The calculations reveal that Yb-$4f$\norbitals constitute isolated highly localized bands below the Fermi level at\nthe absence of SOC, and the bands are split into the $j = 7/2$ and $j = 5/2$\nstates with SOC. The isolated highly localized bands can lead to very large\nSeebeck coefficient and very low electrical conductivity in p-type doping by\nproducing very large effective mass of the carrier. It is proved that isolated\nhighly localized bands have very strong stability again strain, which is very\nimportant for practical application. When the onsite Coulomb interaction is\nadded to the Yb-$4f$ orbitals, isolated highly localized bands persist, and\nonly their relative positions in the gap change. These findings open a new\nwindow to search for novel electronic structures in 2D materials."
    },
    {
        "anchor": "Theoretical Atomic Volumes of fcc Thorium and Plutonium: The zero-presssure zero-temperature equilibrium volume and bulk modulus are\ncalculated for fcc Th and Pu by two independent all-electron, full-potential,\nelectronic-structure methods: the full-potential linear augmented-plane-wave\n(FLAPW) method and the linear combinations of Gaussian type orbitals-fitting\nfunction (LCGTO-FF) method. The results produced by these two distinctly\ndifferent electronic-structure techniques are in excellent agreement with each\nother, but differ significantly from a previous calculation using the\nfull-potential linear muffin-tin-orbital (FP-LMTO) method. The theoretically\ncalculated equilibrium volumes are nearly 10% larger than the previous FP-LMTO\ncalculations. While the new theoretical volume for Th is in good agreement with\nexperiment when the generalized gradient approximation is used, the calculated\nequilibrium volume for fcc Pu remains substantially smaller than experiment in\nqualitative agreement with previous calculations.",
        "positive": "Transient spin injection efficiencies at ferromagnet/metal interfaces: Spin injection across interfaces driven by ultrashort optical pulses on\nfemtosecond timescales constitutes a new way to design spintronics\napplications. Targeted utilization of this phenomenon requires knowledge of the\nefficiency of non-equilibrium spin injection. From a quantitative comparison of\nab-initio time-dependent density functional theory and interface-sensitive,\ntime-resolved non-linear optical experiment, we determine the spin injection\nefficiencies (SIE) across ferromagnetic/metal interfaces and discuss their\nmicroscopic origin, i.e. the influence of spin-orbit coupling and the interface\nelectronic structure. Moreover, we find that the SIE can be optimized through\nlaser pulse and materials parameters, namely the fluence, pulse duration, and\nsubstrate material."
    },
    {
        "anchor": "Ultrafast, highly-sensitive infrared photodetectors based on\n  two-dimensional oxyselenide crystals: Infrared detection and sensing is deeply embedded in modern technology and\nhuman society and its development has always been benefitting from the\ndiscovery of new photoelectric response materials. The rise of two-dimensional\n(2D) materials, thanks to their distinct electronic structure, extreme\ndimensional confinement and strong light-matter interactions, provides new\nmaterial platform for next-generation infrared photodetection. Ideal infrared\ndetectors should have fast respond, high sensitivity and air-stability, which\nis rare to meet at the same time for all existing 2D materials, either\ngraphene, transition metal dichalcogenide or black phosphorous. Herein we\ndemonstrate a new infrared photodetector based on 2D Bi2O2Se crystals, whose\nmain characteristics are superb in the whole 2D family: high sensitivity of ~65\nA/W at 1200 nm and ultrafast intrinsic photoresponse of ~1 ps at room\ntemperature. Such great performance is attributed to the suitable electronic\nbandgap and high carrier mobility of 2D oxyselenide. With additional merits of\nmass production, excellent stability and flexibility, 2D oxyselenide detectors\nshould open new avenues in highly-sensitive, high-speed, low-cost, flexible\ninfrared photodetection and imaging.",
        "positive": "Phase diagram of mixed system of ferroelectric relaxors in the random\n  field theory framework: We suggest a random field based model for calculation of physical properties\nof mixed ferroelectric relaxors. Our model naturally incorporates the different\norientations of electric dipoles (related to different solid solution\ncomponents) as well as the contribution of nonlinear and correlation effects of\nrandom field. We calculate the transition temperature $T_c$ as well as\nconcentrational and temperature dependence of order parameters."
    },
    {
        "anchor": "Supercell formation in epitaxial rare-earth ditelluride thin films: Square net tellurides host an array of electronic ground states and commonly\nexhibit charge-density-wave ordering. Here we report the epitaxy of\nDyTe$_{2-\\delta}$ on atomically flat MgO (001) using molecular beam epitaxy.\nThe films are single phase and highly oriented as evidenced by transmission\nelectron microscopy and X-ray diffraction measurements. Epitaxial strain is\nevident in films and is relieved as the thickness increases up to a value of\napproximately 20 unit cells. Diffraction features associated with a supercell\nin the films are resolved which is coupled with Te-deficiency. First principles\ncalculations attribute the formation of this defect lattice to nesting\nconditions in the Fermi surface, which produce a periodic occupancy of the\nconducting Te square-net, and opens a band gap at the chemical potential. This\nwork establishes the groundwork for exploring the role of strain in tuning\nelectronic and structural phases of epitaxial square-net tellurides and related\ncompounds.",
        "positive": "High temperature memory in (Pb/La)(Zr/Ti)O_3 as intrinsic of the relaxor\n  state rather than due to defect relaxation: It has been recently shown that the memory of multiple aging stages, a\nphenomenon considered possible only below the glass transition of some glassy\nsystems, appears also above that temperature range in the relaxor ferroelectric\n(Pb/La)(Zr/Ti)O_3 (PLZT). Doubts exist whether memory at such high temperature\nis intrinsic of the glassy relaxor state or is rather due to migration of\nmobile defects. It is shown that the memory in the electric susceptibility and\nelastic compliance of PLZT 9/65/35 is not enhanced but depressed by mobile\ndefects like O vacancies, H defects and mobile charges resulting from their\nionization. In addition, memory is drastically reduced at La contents slightly\nbelow the relaxor region of the phase diagram, unless aging is protracted for\nlong times (months at room temperature). This is considered as evidence that in\nthe non relaxor case memory is indeed due to slow migration of defects, while\nin the La rich case it is intrinsic of the relaxor state, even above the\ntemperature of the susceptibility maximum."
    },
    {
        "anchor": "On-Surface Carbon Nitride Growth from Polymerization of\n  2,5,8-Triazido-s-heptazine: Carbon nitrides have recently come into focus for photo- and thermal\ncatalysis, both as support materials for metal nanoparticles as well as\nphotocatalysts themselves. While many approaches for the synthesis of\nthree-dimensional carbon nitride materials are available, only top-down\napproaches by exfoliation of powders lead to thin film flakes of this\ninherently two-dimensional material. Here, we describe an in situ on-surface\nsynthesis of monolayer 2D carbon nitride films, as a first step towards precise\ncombination with other 2D materials. Starting with a single monomer precursor,\nwe show that 2,5,8-triazido-s-heptazine (TAH) can be evaporated intact,\ndeposited on a single crystalline Au(111) or graphite support, and activated\nvia azide decomposition and subsequent coupling to form a covalent\npolyheptazine network. We demonstrate that the activation can occur in three\npathways, via electrons (X-ray illumination), photons (UV illumination) and\nthermally. Our work paves the way to coat materials with extended carbon\nnitride networks which are, as we show, stable under ambient conditions.",
        "positive": "Tunable light-emission through the range 1.8-3.2 eV and p-type\n  conductivity at room temperature for nitride semiconductors, Ca(Mg1-xZnx)2N2\n  (x=0-1): The ternary nitride CaZn2N2, composed only of earth-abundant elements, is a\nnovel semiconductor with a band gap of 1.8 eV. First-principles calculations\npredict that continuous Mg substitution at the Zn site will change the optical\nband gap in a wide range from ~3.3 eV to ~1.9 eV for Ca(Mg1-xZnx)2N2 (x = 0-1).\nIn this study, we demonstrate that a solid-state reaction at ambient pressure\nand a high-pressure synthesis at 5 GPa produce x = 0 and 0.12, and x = 0.12-1\npolycrystalline samples, respectively. It is experimentally confirmed that the\noptical band gap can be continuously tuned from ~3.2 eV to ~1.8 eV, a range\nvery close to that predicted by theory. Band-to-band photoluminescence is\nobserved at room temperature in the ultravioletfired region depending on x. A\n2% Na doping at the Ca site of CaZn2N2 converts its highly resistive state to a\np-type conducting state. Particularly, the x = 0.50 sample exhibits intense\ngreen emission with a peak at 2.45 eV (506 nm) without any other emission from\ndeep-level defects. These features meet the demands of the III-V group nitride\nand arsenide/phosphide light-emitting semiconductors."
    },
    {
        "anchor": "An improved exchange-correlation potential for polarizability and\n  dissociation in DFT: We propose a novel approach to the problem of polarizabilities and\ndissociation in electric fields from the static limit of the Vignale-Kohn (VK)\nfunctional. We consider the response to the purely scalar part of the VK\nresponse potential.This potential has ground-state properties that notably\nimprove over the full VK response density and over usual (semi-)local\nfunctionals. The correct qualitative behavior of our potentials means that it\nis expected to work well for polarizabilities in cases such as the H$_2$ chain,\nand it will also correctly dissociate open-shell fragments in a field.",
        "positive": "RBS/Channeling characterization of Ru(0001) and thin epitaxial\n  Ru/Al$_2$O$_3$(0001) films: Thin epitaxial films of metals on insulating substrates are essential for\nmany applications, as conducting layers, in magnetic devices or as templates\nfor further growth. In this work, we report on the growth of epitaxial Ru films\non single-crystalline Al$_2$O$_3$(0001) substrates by magnetron sputtering and\ntheir subsequent systematic characterization using Rutherford backscattering\nspectrometry of He ions both in random and in channeling conditions. We include\nresults of a Ru(0001) single crystal for comparison. Analysis of channeling\nshows that films thicker than 35 nm grow with (0001) orientation, a\nwell-defined epitaxial relation with the substrate and a high degree of crystal\nquality, comparable to the Ru(0001) single crystal. Thinner films of down to 7\nnm in thickness, for which relaxation of epitaxial strain is not complete,\nproduce a similar degree of dechanneling. The surface of the films can be\nprepared in a clean and ordered state in order to allow further epitaxial\ngrowth on top."
    },
    {
        "anchor": "Proximity-free enhancement of anomalous Nernst effects in metallic\n  multilayers: The anomalous Nernst effect (ANE) has been investigated in\nalternately-stacked multilayer films comprising paramagnetic and ferromagnetic\nmetals. We found that the ANE is enhanced with increasing the number of the\nparamagnet/ferromagnet interfaces with keeping the total thickness of the films\nconstant, and that the enhancement appears even in the absence of magnetic\nproximity effects; similar behavior was observed not only in Pt/Fe multilayers\nbut also in Au/Fe and Cu/Fe multilayers free from proximity ferromagnetism.\nThis universal enhancement of the ANE in the metallic multilayers suggests the\npresence of unconventional interface-induced thermoelectric conversion in the\nFe films attached to the paramagnets.",
        "positive": "Lattice dynamics of endotaxial silicide nanowires: Self-organized silicide nanowires are considered as main building blocks of\nfuture nanoelectronics and have been intensively investigated. In\nnanostructures, the lattice vibrational waves (phonons) deviate drastically\nfrom those in bulk crystals, which gives rise to anomalies in thermodynamic,\nelastic, electronic, and magnetic properties. Hence, a thorough understanding\nof the physical properties of these materials requires a comprehensive\ninvestigation of the lattice dynamics as a function of the nanowire size. We\nperformed a systematic lattice dynamics study of endotaxial FeSi$_2$ nanowires,\nforming the metastable, surface-stabilized $\\alpha$-phase, which are in-plane\nembedded into the Si(110) surface. The average widths of the nanowires ranged\nfrom 24 to 3 nm, their lengths ranged from several $\\mu$m to about 100 nm. The\nFe-partial phonon density of states, obtained by nuclear inelastic scattering,\nexhibits a broadening of the spectral features with decreasing nanowire width.\nThe experimental data obtained along and across the nanowires unveiled a\npronounced vibrational anisotropy that originates from the specific orientation\nof the tetragonal $\\alpha$-FeSi$_2$ unit cell on the Si(110) surface. The\nresults from first-principles calculations are fully consistent with the\nexperimental data and allow for a comprehensive understanding of the lattice\ndynamics of endotaxial silicide nanowires."
    },
    {
        "anchor": "Optical and electrical properties of Nd3+doped Na2O-ZnO-TeO2 Material: Neodymium doped Na2O-ZnO-TeO2 (NZT) glasses were prepared by the conventional\nmelt quenching technique. DTA and TG were used to confirmation of glass\npreparation through the glass transition temperature at 447{\\deg}C for the\nglass system. The analysis of FTIR spectra and X-ray diffraction described the\nnature of the samples were ionic and amorphous respectively. The optical\nbandgap energy was estimated using absorption spectra and found to be decreased\nfrom 2.63eV to 1.32 eV due to the increase of doping concentration. The\nintensity of the emission spectra was enhanced for the higher concentration of\nNd3+ ions. The dielectric constant of the glass samples was found to be\nconstant for the large range of frequency (3 kHz to 1 MHz). The variation of\nconductivity with the temperature of the samples had shown the Arrhenius\nmechanism of conduction.",
        "positive": "Heat Capacity of oxide scale in the range from 0 C to 1300 C:\n  Generalized estimates with account for movability of phase transitions: The known data on the heat capacity of magnetite (Fe3O4), hematite (Fe2O3)\nand iron (Fe) at different temperatures are approximated by formulas containing\nphase transition temperatures as varying parameters. This allows to take into\naccount the effect of phase transition shifts, for example, due to impurities,\nlattice defects, grain sizes or high cooling rates. For this purpose, the\nentire target temperature range from 0 C to 1300 C is divided by phase\ntransition temperatures into separate intervals. The conjugation of the\napproximating functions between the intervals at the magnetic transition point\nis performed without a gap, and at the point of polymorphic transformation\n(alpha Fe - gamma Fe) with a finite gap of heat capacity values. For wustite\nFe1-xO which does not experience phase transformations, the temperature\ndependence of the heat capacity is approximated by a single smooth function. In\ncombination with previously obtained formulas for the density of iron oxides\nand iron the proposed approximations allow us to estimate the specific mass\nheat capacity of oxide scale depending of its structural composition and\ntemperature. By model calculations it is shown that at temperatures of 200 C\nand 900 C specific mass heat capacity of oxide scale practically does not\ndepend on the percentage of its individual components and is approximately 750\nand 850 J/(kg K) respectively. At a temperature of about 575 C, on contrary,\nactually possible variations in the composition of oxide scale can lead to a\nchange in its specific heat capacity from 850 to 1150 J/(kg K). The obtained\ndependencies are recommended for use in mathematical modeling of production and\nprocessing of steel products in the presence of oxide scale on their surface"
    },
    {
        "anchor": "First principles study of the surface of silica and sodium silicate\n  glasses: We use \\textit{ab initio} molecular dynamics simulations to investigate the\nproperties of the dry surface of pure silica and sodium silicate glasses. The\nsurface layers are defined based on the atomic distributions along the\ndirection ($z-$direction) perpendicular to the surfaces. We show that these\nsurfaces have a higher concentration of dangling bonds as well as two-membered\n(2M) rings than the bulk samples. Increasing concentration of Na$_2$O reduces\nthe proportion of structural defects.\n  From the vibrational density of states, one concludes that 2M rings have a\nunique vibrational signature at a frequency $\\approx850$~cm$^{-1}$, compatible\nwith experimental findings.\n  We also find that, due to the presence of surfaces, the atomic vibration in\nthe $z-$direction is softer than for the two other directions. The electronic\ndensity of states shows clear the differences between the surface and interior\nand we can attribute these to specific structural units. Finally, the analysis\nof the electron localization function allows to get insight on the influence of\nlocal structure and the presence of Na on the nature of chemical bonding in the\nglasses.",
        "positive": "Unraveling the magnetic softness in Fe-Ni-B based nanocrystalline\n  material by magnetic small-angle neutron scattering: We employ magnetic small-angle neutron scattering to investigate the magnetic\ninteractions in $(Fe_{0.7}Ni_{0.3})_{86}B_{14}$ alloy, a HiB-NANOPERM-type soft\nmagnetic nanocrystalline material, which exhibits an ultrafine microstructure\nwith an average grain size below 10 nm. The neutron data reveal a significant\nspin-misalignment scattering, which is mainly related to the jump of the\nlongitudinal magnetization at internal particle-matrix interfaces. The field\ndependence of the neutron data can be well described by the micromagnetic\nsmall-angle neutron scattering theory. In particular, the theory explains the\n'clover-leaf-type' angular anisotropy observed in the purely magnetic neutron\nscattering cross section. The presented neutron-data analysis also provides\naccess to the magnetic interaction parameters, such as the exchange-stiffness\nconstant, which plays a crucial role towards the optimization of the magnetic\nsoftness of Fe-based nanocrystalline materials."
    },
    {
        "anchor": "Hierarchical Nano-Porous Layer with Persistent Superhydrophilicity and\n  High Transparency Etched onto Silicate Glass: We have developed a hierarchical nano-porous layer (HNL) on a silicate glass\nby simple alkaline etching method. The HNL has a three-dimensionally-continuous\nsponge-like structure with a pore size of a few tens of nm at its apparent\nsurface. The pore size gradually decreases from the apparent surface to the\ninterface of the porous layer and the bulk substrate. This HNL gives two\nsignificant properties to glass: (1) higher optical transparency than untreated\nglass by 7% for all over the visible light. (2) long persistent\nsuperhydrophilicity with a water contact angle of 5 degree for more than 140\ndays. The superhydrophilicity also realizes anti-fogging and anti-fouling\nfunctionalities.",
        "positive": "Photocarrier relaxation in two-dimensional semiconductors: Two-dimensional (2D) crystals of semiconducting transition metal\ndichalcogenides (TMD) absorb a large fraction of incident photons in the\nvisible frequencies despite being atomically thin. It has been suggested that\nthe strong absorption is due to the parallel band or \"band nesting\" effect and\ncorresponding divergence in the joint density of states. Here, we show using\nphotoluminescence excitation spectroscopy that the band nesting in mono- and\nbilayer MX$_2$ (M = Mo, W and X = S, Se) results in excitation-dependent\ncharacteristic relaxation pathways of the photoexcited carriers. Our\nexperimental and simulation results reveal that photoexcited electron-hole\npairs in the nesting region spontaneously separate in the $k$-space, relaxing\ntowards immediate band extrema with opposite momentum. These effects imply that\nthe loss of photocarriers due to direct exciton recombination is temporarily\nsuppressed for excitation in resonance with band nesting. Our findings\nhighlight the potential for efficient hot carrier collection using these\nmaterials as the absorbers in optoelectronic devices."
    },
    {
        "anchor": "The structural, elastic, electronic and optical properties of MgCu under\n  pressure: A first-principles study: The effect of pressure on the structural, elastic and electronic properties\nof the intermetallic compound MgCu with a CsCl-type structure have been\ninvestigated using ab-initio technique. The optical properties have been\nstudied under normal pressure. We have carried out the plane-wave\npseudopotential approach within the framework of the first-principle density\nfunctional theory (DFT) implemented within the CASTEP code. The calculated\nstructural parameters show a good agreement with the experimental and other\ntheoretical results.",
        "positive": "CO oxidation by Pt2/Fe3O4: metastable dimer and support configurations\n  facilitate lattice oxygen extraction: Heterogeneous catalysts based on sub-nanometer metal clusters often exhibit\nstrongly size-dependent properties, and the addition or removal of a single\natom can make all the difference. Identifying the most active species and\ndeciphering the reaction mechanism is extremely difficult, however, because it\nis often not clear how the catalyst evolves in operando. Here, we utilize a\ncombination of atomically resolved scanning probe microscopies, spectroscopic\ntechniques, and density functional theory (DFT)-based calculations to study CO\noxidation by a model Pt/Fe3O4(001) single-atom catalyst. We demonstrate that\n(PtCO)2 dimers, formed dynamically through the agglomeration of mobile\nPt-carbonyl species, catalyse a reaction involving the oxide support to form\nCO2. Pt2 dimers produce one CO2 molecule before falling apart into two adatoms,\nreleasing the second CO. Interestingly, Olattice extraction only becomes facile\nwhen both the Pt-dimer and the Fe3O4 support can access metastable\nconfigurations, suggesting that substantial, concerted rearrangements of both\ncluster and support must be considered for reactions occurring at elevated\ntemperature."
    },
    {
        "anchor": "Ferroelectric thin films properties: depolarization field and Landau\n  free-energy coefficients renormalization: The calculation of the polarization in ferroelectric thin films is performed\nusing an analytical solution of the Euler-Lagrange differential equation with\nboundary conditions with different extrapolation lengths of positive sign on\nthe surfaces. The depolarization field effect is taken into account in the\nmodel for a short-circuited single domain film, that is a perfect insulator. It\nis shown that the calculation of the polarization and other properties profiles\nand average values can be reduced to the minimization of the free energy\nexpressed as a power series of the average polarization with a renormalized\ncoefficient which depends on temperature, film thickness, extrapolation\nlengths, and a coefficient for the polarization gradient term in the free\nenergy functional, the depolarization field being also included into the\nrenormalized coefficient. The function defining the space distribution\nproperties is calculated as well and its amplitude is shown to coincide with\nthe average polarization. The detailed calculations of the spontaneous\npolarization, dielectric susceptibility and pyrocoefficient is performed. The\ndivergence of the dielectric susceptibility and pyrocoefficient for critical\nparameters of the thickness induced ferroelectric phase transition, namely at\ntemperature T(cl) and critical length l(c), is shown to exist with and without\nthe depolarization field contribution, although the values of T(cl) and l(c)\nare different in both cases. The detailed analysis of the depolarization field\nspace distribution and of this field dependence on temperature and film\nthickness is performed.",
        "positive": "Atomistic Simulations of Flash Memory Materials Based on Chalcogenide\n  Glasses: In this chapter, by using ab-initio molecular dynamics, we introduce the\nlatest simulation results on two materials for flash memory devices: Ge2Sb2Te5\nand Ge-Se-Cu-Ag. This chapter is a review of our previous work including some\nof our published figures and text in Cai et al. (2010) and Prasai & Drabold\n(2011) and also includes several new results."
    },
    {
        "anchor": "Effect of the reduction process on the field emission performance of\n  reduced graphene oxide cathodes: The electron field emission (FE) properties of reduced graphene oxide (rGO)\ncathodes produced by three different reduction methods were assessed and\ncompared. In particular, chemical reduction techniques, using either NaOH or\nKOH as reducing agents, were compared with thermal reduction (TR) methods. Xray\nphotoelectron spectroscopy (XPS) measurements revealed that different reduction\ntechniques led to different GO lattice parameters. Furthermore, the work\nfunction measured with ultraviolet photoelectron spectroscopy (UPS) varied\namong the samples giving rise to different electron emission characteristics.\nIn particular, the cathodes prepared by the TR method presented the best FE\nperformance, showing a turnon field of as low as ca. 1.8 V mm^-1 and a field\nenhancement factor of ca. 1300, which was very close however to that shown by\nthe NaOH-reduced sheets. The worst FE properties were exhibited by the\nKOH-reduced nanosheets. In light of the above results, the role of the\ndifferent reduction techniques as well as the final rGO lattice characteristics\nwith regards to the emission performance are evaluated and discussed.",
        "positive": "High-angular resolution electron backscatter diffraction as a new tool\n  for mapping lattice distortion in geological minerals: Analysis of distortions of the crystal lattice within individual mineral\ngrains is central to the investigation of microscale processes that control and\nrecord tectonic events. These distortions are generally combinations of lattice\nrotations and elastic strains, but a lack of suitable observational techniques\nhas prevented these components being mapped simultaneously and routinely in\nearth science laboratories. However, the technique of high-angular resolution\nelectron backscatter diffraction (HR-EBSD) provides the opportunity to\nsimultaneously map lattice rotations and elastic strains with exceptional\nprecision, on the order of 0.01 degree for rotations and 10-4 in strain, using\na scanning electron microscope. Importantly, these rotations and lattice\nstrains relate to densities of geometrically necessary dislocations and\nresidual stresses. Recent works have begun to apply and adapt HR-EBSD to\ngeological minerals, highlighting the potential of the technique to provide new\ninsights into the microphysics of rock deformation. Therefore, the purpose of\nthis overview is to provide a summary of the technique, to identify caveats and\ntargets for further development, and to suggest areas where it offers potential\nfor major advances. In particular, HREBSD is well suited to characterising the\nroles of different dislocation types during crystal plastic deformation and to\nmapping heterogeneous internal stress fields associated with specific\ndeformation mechanisms/microstructures or changes in temperature, confining\npressure, or applied deviatoric stress. These capabilities make HR-EBSD a\nparticularly powerful new technique for analysing the microstructures of\ndeformed geological materials."
    },
    {
        "anchor": "First-principles calculations of spin spirals in Ni2MnGa and Ni2MnAl: We report here non-collinear magnetic configurations in the Heusler alloys\nNi2MnGa and Ni2MnAl which are interesting in the context of the magnetic shape\nmemory effect. The total energies for different spin spirals are calculated and\nthe ground state magnetic structures are identified. The calculated dispersion\ncurves are used to estimate the Curie temperature which is found to be in good\nagreement with experiments. In addition, the variation of the magnetic moment\nas a function of the spiral structure is studied. Most of the variation is\nassociated with Ni, and symmetry constraints relevant for the magnetization are\nidentified. Based on the calculated results, the effect of the constituent\natoms in determining the Curie temperature is discussed.",
        "positive": "Self-Assembled Triply Periodic Minimal Surfaces as moulds for Photonic\n  Band Gap Materials: We propose systems with structures defined by self-assembled triply periodic\nminimal surfaces (STPMS) as candidates for photonic bandgap materials. To\nsupport our proposal we have calculated the photonic bands for different STPMS\nand we have found that, at least, the double diamond and gyroid structures\npresent full photonic bandgaps. Given the great variety of systems which\ncrystalize in these structures, the diversity of possible materials that form\nthem and the range of lattice constants they present, the construction of\nphotonic bandgap materials with gaps in the visible range may be presently\nwithin reach."
    },
    {
        "anchor": "Thermal Sublimation: a Scalable and Controllable Thinning Method for the\n  Fabrication of Few-Layer Black Phosphorus: In this work, we reported uniform layer-by-layer sublimation of black\nphosphorus under heating below 600 K. The uniformity and crystallinity of BP\nsamples after thermal thinning were confirmed by Raman spectra and 2D Raman\nimaging. A uniform and crystalline bilayer black phosphorus flake with an area\nof 180 um^2 was prepared with this method. No micron scale defects were\nobserved. The sublimation rate of BP was around 0.18 nm / min at 500 K and 1.5\nnm / min at 550 K. Both room and high temperature Raman peak intensity ratio\nSi/A2g vs. BP thickness relations were established for in-situ thickness\ndetermination. The sublimation thinning method was shown to be a controllable\nand scalable approach to prepare few-layer black phosphorus.",
        "positive": "1/t pressure and fermion behaviour of water in two dimensions: A variety of metal vacuum systems display the celebrated 1/t pressure, namely\npower-law dependence on time t, with the exponent close to unity, the origin of\nwhich has been a long-standing controversy. Here we propose a chemisorption\nmodel for water adsorbates, based on the argument for fermion behaviour of\nwater vapour adsorbed on a stainless-steel surface, and obtain analytically the\npower-law behaviour of pressure, with an exponent of unity. Further, the model\npredicts that the pressure should depend on the temperature T according to\nT^(3/2), which is indeed confirmed by our experiment. Our results should help\nelucidate the unique characteristics of the adsorbed water."
    },
    {
        "anchor": "On fracture criteria for dynamic crack propagation in elastic materials\n  with couple stresses: The focus of the article is on fracture criteria for dynamic crack\npropagation in elastic materials with microstructures. Steady-state propagation\nof a Mode III semi-infinite crack subject to loading applied on the crack\nsurfaces is considered. The micropolar behavior of the material is described by\nthe theory of couple-stress elasticity developed by Koiter. This constitutive\nmodel includes the characteristic lengths in bending and torsion, and thus it\nis able to account for the underlying microstructures of the material. Both\ntranslational and micro-rotational inertial terms are included in the balance\nequations, and the behavior of the solution near to the crack tip is\ninvestigated by means of an asymptotic analysis. The asymptotic fields are used\nto evaluate the dynamic J-integral for a couple-stress material, and the energy\nrelease rate is derived by the corresponding conservation law. The propagation\nstability is studied according to the energy-based Griffith criterion and the\nobtained results are compared to those derived by the application of the\nmaximum total shear stress criterion.",
        "positive": "Flexible Sensory Platform Based on an Electrolyte-Gated Oxide Neuron\n  Transistor: Inspired by the dendritic integration and spiking operation of a biological\nneuron, flexible oxide-based neuron transistors gated by solid-state\nelectrolyte films are fabricated on flexible plastic substrates for biochemical\nsensing applications. When a quasi-static dual-gate laterally synergic sensing\nmode is adopted, the neuron transistor sensor shows a high pH sensitivity of\n~105 mV/pH, which is higher than the Nernst limit. Our results demonstrate that\nsingle-spike dynamic mode can remarkably improve the pH sensitivity, reduce\nresponse/recover time and power consumption. We also find that appropriate\ndepression applied on the sensing gate electrode can further enhance the pH\nsensitivity and reduce the power consumption. Our flexible neuron transistors\nprovide a new-concept sensory platform for biochemical detection with high\nsensitivity, rapid response and ultralow power consumption."
    },
    {
        "anchor": "Thermal Expansion and Diffusion Coefficients of Carbon Nanotube-Polymer\n  Composites: Classical molecular dynamics (MD) simulations employing Brenner potential for\nintra-nanotube interactions and Van der Waals forces for polymer-nanotube\ninterfaces are used to invetigate the thermal expansion and diffusion\ncharacteristics of carbon nanotube-polyethylene composites. Additions of carbon\nnanotubes to polymer matrix are found to increase the glass transition\ntemperature Tg, and thermal expansion and diffusion coefficients in the\ncomposite above Tg. These findings could have implications in CNT composite\nprocessing, coating and painting applications.",
        "positive": "Graphene to Graphane: A Theoretical Study: Graphane is a two-dimensional system consisting of a single layer of fully\nsaturated (sp$^3$ hybridization) carbon atoms. In an ideal graphane structure\nC-H bonds exhibit an alternating pattern (up and down with relation to the\nplane defined by the carbon atoms). In this work we have investigated using\n\\textit{ab initio} and reactive molecular dynamics simulations the role of H\nfrustration (breaking the H atoms up and down alternating pattern) in\ngraphane-like structures. Our results show that significant percentage of\nuncorrelated H frustrated domains are formed in the early stages of the\nhydrogenation process leading to membrane shrinkage and extensive membrane\ncorrugations. These results also suggest that large domains of perfect\ngraphane-like structures are unlikely to be formed, H frustrated domains are\nalways present."
    },
    {
        "anchor": "Spin transport and dynamics in all-oxide perovskite\n  La$_{2/3}$Sr$_{1/3}$MnO$_3$/SrRuO$_3$ bilayers probed by ferromagnetic\n  resonance: Thin films of perovskite oxides offer the possibility of combining emerging\nconcepts of strongly correlated electron phenomena and spin current in magnetic\ndevices. However, spin transport and magnetization dynamics in these complex\noxide materials are not well understood. Here, we experimentally quantify spin\ntransport parameters and magnetization damping in epitaxial perovskite\nferromagnet/paramagnet bilayers of La$_{2/3}$Sr$_{1/3}$MnO$_3$/SrRuO$_3$\n(LSMO/SRO) by broadband ferromagnetic resonance spectroscopy. From the SRO\nthickness dependence of Gilbert damping, we estimate a short spin diffusion\nlength of $\\lesssim$1 nm in SRO and an interfacial spin-mixing conductance\ncomparable to other ferromagnet/paramagnetic-metal bilayers. Moreover, we find\nthat anisotropic non-Gilbert damping due to two-magnon scattering also\nincreases with the addition of SRO. Our results demonstrate LSMO/SRO as a\nspin-source/spin-sink system that may be a foundation for examining\nspin-current transport in various perovskite heterostructures.",
        "positive": "Interlayer-spin-interaction-driven Sliding Ferroelectricity in a van der\n  Waals Magnetic Heterobilayer: Sliding ferroelectricity is widely existed in van der Waals (vdW)\ntwo-dimensional (2D) multilayers, exhibiting great potential on low-dissipation\nnon-volatile memories. However, in a vdW heterostructure, interlayer sliding\nusually fails to reverse or distinctly change the electric polarization, which\nmakes the electrical control difficult in practice. Here we propose that in a\nvdW magnetic system, the interlayer spin interaction could provide an extra\ndegree-of-freedom to remarkably tune the electric polarization. Combining\ntight-binding model analysis and first-principles calculations, we show that in\nthe CrI3/MnSe2 and other vdW magnetic heterobilayers, the switching of the\ninterlayer magnetic order can greatly change, even reverse the off-plane\nelectronic polarization. Furthermore, interlayer sliding causes a non-volatile\nswitching of the magnetic order and, thus, reverses the electric polarization,\nsuggesting a non-volatile magnetoelectric coupling effect. These findings will\nsignificantly advances the development of 2D ferroelectrics and multiferroics\nfor spintronic applications."
    },
    {
        "anchor": "Compression and phase diagram of lithium hydrides at elevated pressures\n  and temperatures by first-principles calculations: High pressure and high temperature properties of AB (A = $^6$Li, $^7$Li; B =\nH, D, T) are investigated with first-principles method comprehensively. It is\nfound that the H$^{-}$ sublattice features in the low-pressure electronic\nstructure near the Fermi level of LiH are shifted to that dominated by the\nLi$^{+}$ sublattice in compression. The lattice dynamics is studied in\nquasi-harmonic approximation, from which the phonon contribution to the free\nenergy and the isotopic effects are accurately modelled with the aid of a\nparameterized double-Debye model. The obtained equation of state (EOS) matches\nperfectly with available static experimental data. The calculated principal\nHugoniot is also in accordance with that derived from shock wave experiments.\nUsing the calculated principal Hugoniot and the previous theoretical melting\ncurve, we predict a shock melting point at 56 GPa and 1923 K. In order to\nestablish the phase diagram for LiH, the phase boundaries between the B1 and B2\nsolid phases are explored. The B1-B2-liquid triple point is determined at about\n241 GPa and 2413 K. The remarkable shift in the phase boundaries by isotopic\neffect and temperature reveal the significant role played by lattice\nvibrations. Furthermore, the Hugoniot of the static-dynamic coupling\ncompression is assessed. Our EOS suggests that a precompression of the sample\nto 50 GPa will allow the shock Hugoniot passing through the triple point and\nentering the B2 solid phase. This transition leads to a discontinuity with 4.6%\nvolume collapse, about four times greater than the same B1-B2 transition at\nzero temperature.",
        "positive": "Macroscopic yarns of FeCl$_{3}$-intercalated collapsed carbon nano-tubes\n  with high doping and stability: Macroscopic arrays of highly crystalline nanocarbons offer the possibility of\nmodifying the electronic structure of their low dimensional constituents, for\nexample through doping, and studying the resulting collective bulk behaviour.\nInsertion of electron donors or acceptors between graphitic layers is an\nattractive method to reversibly increase charge carrier concentra-tion without\ndisruption of the sp$2$-conjugated system. This work demonstrates FeCl$_{3}$\nintercalation into fibres made up of collapsed (flattened) carbon nanotubes.\nThe bundles of collapsed CNTs, similar to crystallites of graphitic\nnanoribbons, host elongated layered FeCl$_{3}$ crystals of hundreds of $nm$\nlong, much longer than previous reports on graphitic materials and directly\nobservable by transmission electron microscopy and X-ray diffraction.\nIntercalated CNT fibres remain stable after months of exposure to ambient\nconditions, partly due to the spontaneous formation of passivating monolayers\nof FeClO at the crystal edge, preventing both desorption of intercalant and\nfurther hydrolysis. Raman spectroscopy shows substantial electron transfer from\nthe CNTs to FeCl$_{3}$, a well-known acceptor, as observed by G band upshifts\nas large as $25 cm^{-1}$. After resolving Raman features for the inner and\nouter layers of the collapsed CNTs, strain and dynamic effect contributions of\ncharge transfer to the Raman upshift could be decoupled, giving a Fermi level\ndownshift of $- 0.72 eV$ and a large average free carrier concentration of\n$5.3X10^{13}$ $cm^{-2}$ ($0.014$ electrons per carbon atom) in the intercalated\nsystem. Four-probe resistivity measurements show an increase in conductivity by\na factor of six upon intercalation"
    },
    {
        "anchor": "An all-electron product-basis set: application to plasmon anisotropy in\n  simple metals: An efficient basis set for products of all-electron wave functions is\nproposed, which comprises plane waves defined over the entire unit cell and\norbitals confined to small non-overlapping spheres. The size of the set and the\nbasis functions are, in principle, independent of the computational parameters\nof the band structure method. The approach is implemented in the extended LAPW\nmethod, and its properties and accuracy are discussed. The method is applied to\nanalyze the dielectric response of the simple metals Al, Na, Li, K, Rb, and Cs\nwith a focus on the origin of the anisotropy of the plasmon dispersion in Al\nand Na. The anisotropy is traced to tiny structures of the one-particle\nexcitation spectra of Al and Na, and relevant experimental observations are\nexplained.",
        "positive": "Thermally excited spin-current in metals with embedded ferromagnetic\n  nanoclusters: We show that a thermally excited spin-current naturally appears in metals\nwith embedded ferromagnetic nanoclusters. When such materials are subjected to\na magnetic field, a spin current can be generated by a temperature gradient\nacross the sample as a signature of electron-hole symmetry breaking in a metal\ndue to the electron spin-flip scattering from polarised magnetic moments. Such\na spin current can be observed via a giant magneto-thermopower which tracks the\npolarisation state of the magnetic subsystem and is proportional to the\nmagnetoresistance. Our theory explains the recent experiment on Co clusters in\ncopper by S. Serrano-Guisan \\textit{et al} [Nature Materials AOP,\ndoi:10.1038/nmat1713 (2006)]"
    },
    {
        "anchor": "Bond order potential for FeSi: A new parameter set has been derived for FeSi using the Albe-Erhart-type bond\norder potential (BOP) and the PONTIFIX code for fitting the parameters on a\nlarge training set of various polymorphs. Ab initio calculations are also\ncarried out to study the relative stability of various polymorphs and to use\nthe obtained data in the training set. The original BOP formalism was unable to\naccount for the correct energetic relationship between the B20\n($\\epsilon$-FeSi) and B2 (CsCl) phases and notoriusly slightly favors\nincorrectly the B2 polymorph. In order to correct this improper behavior the\nBOP potential has been extended by a Columbic term (BOP+C) in order to account\nfor the partial ionic character of FeSi. Using this potential we are able to\naccount for the correct phase order between the most stable B20 and B2 (CsCl)\npolymorphs when the net atomic charges are properly set. Although this brings\nin a new somewhat uncertain parameter (the net charges) one can adjust properly\nthe BOP+C potential for specific problems. To demonstrate this we study under\nhigh pressure the B2 phase which becomes more stable vs. B20 as it is found\nexperimentally and expected to be taken place in the Earth mantle. The obtained\nBOP has also been tested for the metallic and semiconducting disilicides\n($\\alpha$-FeSi$_2$ and $\\beta$-FeSi$_2$) and for the Si/$\\beta$-FeSi$_2$\nheterostructure. The obtained BOP, as many other BOP, overestimates the melting\npoint ($T_m$) of the B20 phase by $\\sim 1000$ K if the parameters in the radial\npart of the potential were obtained according to the Pauling relation (regular\nway).",
        "positive": "Symmetry of the Hyperfine and Quadrupole Interactions of Boron Vacancies\n  in a Hexagonal Boron Nitride: The concept of optically addressable spin states of deep level defects in\nwide band gap materials is successfully applied for the development of quantum\ntechnologies. Recently discovered negatively charged boron vacancy defects (VB)\nin hexagonal boron nitride (hBN) potentially allow a transfer of this concept\nonto atomic thin layers due to the van der Waals nature of the defect host.\nHere, we experimentally explore all terms of the VB spin Hamiltonian reflecting\ninteractions with the three nearest nitrogen atoms by means of conventional\nelectron spin resonance and high frequency (94 GHz) electron-nuclear double\nresonance. We establish symmetry, anisotropy, and principal values of the\ncorresponding hyperfine interaction (HFI) and nuclear quadrupole interaction\n(NQI). The HFI can be expressed in the axially symmetric form as Aperp = 45.5\nMHz and Apar = 87 MHz, while the NQI is characterized by quadrupole coupling\nconstant Cq = 1.96 MHz with slight rhombisity parameter n = (Pxx - Pyy)/Pzz =\n-0.070. Utilizing a conventional approach based on a linear combination of\natomic orbitals and HFI values measured here, we reveal that almost all spin\ndensity (84 %) of the VB electron spin is localized on the three nearest\nnitrogen atoms. Our findings serve as valuable spectroscopic data and direct\nexperimental demonstration of the VB spin localization in a single two\ndimensional BN layer."
    },
    {
        "anchor": "Signature of weakly coupled $f$ electrons and conduction electrons in\n  magnetic Weyl semimetal candidates PrAlSi and SmAlSi: Magnetic topological materials are a class of compounds with the underlying\ninterplay of nontrivial band topology and magnetic spin configuration.\nExtensive interests have been aroused due to their application potential\ninvolved with an array of exotic quantum states. With angle-resolved\nphotoemission spectroscopy and first-principles calculations, here we study the\nelectronic properties of two magnetic Weyl semimetal candidates PrAlSi and\nSmAlSi. Though the two compounds harbor distinct magnetic ground states\n(ferromagnetic and antiferromagnetic for PrAlSi and SmAlSi, respectively) and\n4$f$ shell fillings, we find that they share quite analogous low-energy band\nstructure. By the measurements across the magnetic transitions, we further\nreveal that there is no evident evolution of the band structure in both\ncompounds and the experimental spectra can be well reproduced by the\nnonmagnetic calculations, together suggesting a negligible effect of the\nmagnetism on their electronic structures and a possibly weak coupling between\nthe localized 4$f$ electrons and the itinerant conduction electrons. Our\nresults offer essential insights into the interactions between magnetism,\nelectron correlations, and topological orders in the $R$Al$X$ ($R$ = light rare\nearth and $X$ = Si or Ge) family.",
        "positive": "Non-Reciprocal Thermal Material by Spatio-Temporal Modulation: The thermal properties of a material with a spatio-temporal modulation in\nboth the thermal conductivity and the mass density are studied. The special\nconfiguration studied here consists of a modulation in a wave-like fashion. It\nis found that these materials behaves, in an effective way, as materials with\nan internal convection-like term that provides them of non-reciprocal\nproperties, in the sense that the flow of heat has different properties when it\npropagates in the same direction or in the opposite one to the modulation of\nthe parameters. An effective medium description is presented which accurately\ndescribes the modulated material, and numerical simulations supports both the\nnon-reciprocal properties and the effective medium description. It is found\nthat these materials are promising candidates for the design of thermal diodes\nand other advanced devices for the control of the heat flow at all scales."
    },
    {
        "anchor": "Electronic Origin of Half-metal to Semiconductor Transition and Colossal\n  Magnetoresistance in Spinel HgCr2Se4: Half-metals are ferromagnets hosting spin-polarized conducting carriers and\ncrucial for spintronics applications. The chromium spinel HgCr2Se4 represents a\nunique type of half-metal, which features a half-metal to semiconductor\ntransition (HMST) and exhibits colossal magnetoresistance (CMR) across the\nferromagnetic-paramagnetic (FM-PM) transition. Using angle-resolved\nphotoemission spectroscopy (ARPES), we find that the Fermi surface of n-type\nHgCr2Se4 (n-HgCr2Se4) consists of a single electron pocket which moves above\nthe Fermi level (EF) upon the FM-PM transition, leading to the HMST. Such a\nLifshitz transition manifests a giant band splitting which originates from the\nexchange interaction unveiled with a specific chemical nonstoichiometry. The\nexchange band splitting and the chemical nonstoichiometry are two key\ningredients to the HMST and CMR, consistent with our ab-initio calculation. Our\nfindings provide spectroscopic evidences of the electronic origin of the\nanomalous properties of HgCr2Se4, which address the unique phase transition in\nhalf-metals.",
        "positive": "Theoretical study of the stability of the tetradymite-like phases of\n  Sb$_2$S$_3$, Bi$_2$S$_3$, and Sb$_2$Se$_3$: We report a comparative theoretical study of the \\textit{Pnma} and\n\\textit{R-3m} phases of Sb$_2$S$_3$, Bi$_2$S$_3$, and Sb$_2$Se$_3$ close to\nambient pressure.\n  Our enthalpy calculations at 0 K show that at ambient pressure the\n\\textit{R-3m} (tetradymite-like) phase of Sb$_2$Se$_3$ is energetically more\nstable than the \\textit{Pnma} phase, contrary to what is observed for\nSb$_2$S$_3$ and Bi$_2$S$_3$, and irrespective of the exchange-correlation\nfunctional employed in the calculations.\n  The result for Sb$_2$Se$_3$ is in contradiction to experiments where all\nthree compounds are usually grown in the \\textit{Pnma} phase.\n  This result is further confirmed by free-energy calculations taking into\naccount the temperature dependence of the unit-cell volumes and phonon\nfrequencies.\n  Lattice dynamics and elastic tensor calculations further show that both\n\\textit{Pnma} and \\textit{R-3m} phases of Sb$_2$Se$_3$ are dynamically and\nmechanically stable at zero applied pressure.\n  Since these results suggest that the formation of the \\textit{R-3m} phase for\nSb$_2$Se$_3$ should be feasible at close to ambient conditions, we provide a\ntheoretical crystal structure and simulated Raman and infrared spectra to help\nin its identification. We also discuss the results of the two published works\nthat have claimed to have synthesized tetradymite-like Sb$_2$Se$_3$.\n  Finally, the stability of the \\textit{R-3m} phase across the three group-15\n\\textit{A$_2$X$_3$} sesquichalcogenides is analysed based on their van der\nWaals gap and X-X in-plane geometry."
    },
    {
        "anchor": "Kinetic Theory of the Heat Capacity of Two-Level Systems: It is shown that measured heat capacity depends on the rate of the\ntemperature variation and on the initial state of a system. It is calculated\nhere in the framework of two-level model. Fenomenological approach gives the\nsame results.",
        "positive": "Deep Learning Order Parameter for Polymer Phase Transition: We report a deep learning (DL) framework viz. deep autoencoder that\nautonomously discovers an appropriate order parameter from molecular dynamics\n(MD) simulation data to characterize the coil to globule phase transition of a\npolymer. The deep autoencoder encodes the 3N dimensional MD trajectory of a\npolymer in a one-dimensional feature space and, subsequently, decodes the\none-dimensional feature to its original 3N dimensional polymer trajectory. The\nfeature space representation of a polymer provides a new order parameter that\naccurately describes the coil to globule phase transition as a function of\ntemperature. This method is very generic and extensible to identify flexible\norder parameters to characterize wide range of phase transitions that take\nplace in polymers and other soft materials. Moreover, this MD-DL approach is\ncomputational very efficient than a pure MD based characterization of phase\ntransition, and has potential implications in accelerating phase prediction."
    },
    {
        "anchor": "Controlling the Local Spin-Polarization at the Organic-Ferromagnetic\n  Interface: By means of ab initio calculations and spin-polarized scanning tunneling\nmicroscopy experiments we show how to manipulate the local spin-polarization of\na ferromagnetic surface by creating a complex energy dependent magnetic\nstructure. We demonstrate this novel effect by adsorbing organic molecules\ncontaining pi(pz)-electrons onto a ferromagnetic surface, in which the\nhybridization of the out-of-plane pz atomic type orbitals with the d-states of\nthe metal leads to the inversion of the spin-polarization at the organic site\ndue to a pz - d Zener exchange type mechanism. As a key result, we demonstrate\nthat it is possible to selectively inject spin-up and spin-down electrons from\nthe same ferromagnetic surface, an effect which can be exploited in future\nspintronic devices.",
        "positive": "Simulation of thermodynamic properties of magnetic transition metals\n  from an efficient tight-binding model: Atomic scale simulations at finite temperature are an ideal approach to study\nthe thermodynamic properties of magnetic transition metals. However, the\ndevelopment of interatomic potentials explicitly taking into account magnetic\nvariables is a delicate task. In this context, we present a tight-binding model\nfor magnetic transition metals in the Stoner approximation. This potential is\nintegrated into a Monte Carlo structural relaxations code where trials of\natomic displacements as well as fluctuations of local magnetic moments are\nperformed to determine the thermodynamic equilibrium state of the considered\nsystems. As an example, the Curie temperature of cobalt is investigated while\nshowing the important role of atomic relaxations. Furthermore, our model is\ngeneralized to other transition metals highlighting a local magnetic moment\ndistribution that varies with the gradual filling of the d states.\nConsequently, the successful validation of the potential for different magnetic\nconfigurations indicates its great transferability makes it a good choice for\natomistic simulations sampling a large configuration space."
    },
    {
        "anchor": "Interplay of octahedral rotations and breathing distortions in charge\n  ordering perovskite oxides: We investigate the structure--property relationships in $AB$O$_3$ perovskites\nexhibiting octahedral rotations and cooperative octahedral breathing\ndistortions (CBD) using group theoretical methods. Rotations of octahedra are\nubiquitous in the perovskite family, while the appearance of breathing\ndistortions -- oxygen displacement patterns that lead to approximately uniform\ndilation and contraction of the $B$O$_6$ octahedra -- are rarer in compositions\nwith a single, chemically unique $B$-site. The presence of a CBD relies on\nelectronic instabilities of the $B$-site cations, either orbital degeneracies\nor valence-state fluctuations, and often appear concomitant with charge order\nmetal--insulator transitions or $B$-site cation ordering. We enumerate the\nstructural variants obtained from rotational and breathing lattice modes and\nformulate a general Landau functional describing their interaction. We use this\ninformation and combine it with statistical correlation techniques to evaluate\nthe role of atomic scale distortions on the critical temperatures in\nrepresentative charge ordering nickelate and bismuthate perovskites. Our\nresults provide new microscopic insights into the underlying\nstructure--property interactions across electronic and magnetic phase\nboundaries, suggesting plausible routes to tailor the behavior of functional\noxides by design.",
        "positive": "Electric field control and optical signature of entanglement in quantum\n  dot molecules: The degree of entanglement of an electron with a hole in a vertically coupled\nself-assembled dot molecule is shown to be tunable by an external electric\nfield. Using atomistic pseudopotential calculations followed by a configuration\ninteraction many-body treatment of correlations, we calculate the electronic\nstates, degree of entanglement and optical absorption. We offer a novel way to\nspectroscopically detect the magnitude of electric field needed to maximize the\nentanglement."
    },
    {
        "anchor": "The Ground state of BiFeO3: Low temperature magnetic phase transitions\n  revisited: Recent neutron diffraction and NMR studies suggest that the incommensurately\nmodulated spin cycloid structure of BiFeO3 is stable down to 4.2 K, whereas DC\n[M(T)] and AC [\\c{hi} ({\\omega}, T)] magnetization, and caloric studies have\nrevealed several magnetic transitions including a spin glass transition around\n25 K. The two sets of observations are irreconcilable and to settle this, it is\nimportant to first verify if the low temperature magnetic transitions are\nintrinsic to BiFeO3 or some of them are offshoots of oxygen vacancies and the\nassociated redox reaction involving conversion of Fe3+ to Fe2+. We present here\nthe results of M (T) and \\c{hi} ({\\omega}, T) measurements on pure and 0.3 wt%\nMnO2 doped BiFeO3 samples in the 2 to 300 K temperature range. It is shown that\nMnO2 doping increases the resistivity of the samples by three orders of\nmagnitude as a result of reduced oxygen vacancy concentration. A comparative\nstudy of the M (T) and AC \\c{hi} ({\\omega}, T) results on two types of samples\nreveals that the transitions around 25 K, 110 K and 250 K may be intrinsic to\nBiFeO3. The widely reported transition at 50 K is argued to be defect induced,\nas it is absent in the doped samples. We also show that the spin glass\ntransition temperature TSG is less than the spin glass freezing temperature\n(Tf), as expected for both canonical and cluster glasses, in marked contrast to\nan earlier report of TSG > Tf which is unphysical. We have also observed a cusp\ncorresponding to the spin glass freezing at Tf in ZFC M (T) data not observed\nso far by previous workers. We argue that the ground state of BiFeO3 consists\nof the coexistence of the spin glass phase with the long range ordered AFM\nphase with a cycloidal spin structure.",
        "positive": "Jahn-Teller, polarity and insulator-to-metal transition in BiMnO3 at\n  high pressure: The interaction of coexisting structural instabilities in multiferroic\nmaterials gives rise to intriguing coupling phenomena and extraordinarily rich\nphase diagrams, both in bulk materials and strained thin films. Here we\ninvestigate the multiferroic BiMnO3 with its peculiar 6s2 electrons and four\ninteracting mechanisms: electric polarity, octahedra tilts, magnetism, and\ncooperative Jahn-Teller distortion. We have probed structural transitions under\nhigh pressure by synchrotron x-ray diffraction and Raman spectroscopy up to 60\nGPa. We show that BiMnO3 displays under pressure a rich sequence of five phases\nwith a great variety of structures and properties, including a metallic phase\nabove 53 GPa and, between 37 and 53 GPa, a strongly elongated monoclinic phase\nthat allows ferroelectricity, which contradicts the traditional expectation\nthat ferroelectricity vanishes under pressure. Between 7 and 37 GPa, the Pnma\nstructure remains remarkably stable but shows a reduction of the Jahn-Teller\ndistortion in a way that differs from the behavior observed in the archetypal\northorhombic Jahn-Teller distorted perovskite LaMnO3."
    },
    {
        "anchor": "Excitons in InP, GaP, GaInP quantum dots: Insights from time-dependent\n  density functional theory: Colloidal quantum dots (QDs) of group III-V are considered as promising\ncandidates for next-generation environmentally friendly light emitting devices,\nyet there appears to be only limited understanding of the underlying electronic\nand excitonic properties. Using large-scale density functional theory with the\nhybrid B3LYP functional solving the single-particle states and time-dependent\ndensity functional theory accounting for the many-body excitonic effects, we\nhave identified the structural, electronic and excitonic optical properties of\nInP, GaP and GaInP QDs containing up to a thousand atoms or more. The\ncalculated optical gap of InP QD appears in excellent agreement with available\nexperiments, and it scales nearly linearly with the inverse diameter. The\nradiative exciton decay lifetime is found to increase surprisingly linearly\nwith increasing the dot size. For GaP QDs, we predict an unusual electronic\nstate crossover at diameter around 1.5 nm whereby the nature of the lowest\nunoccupied molecular orbital (LUMO) state switches its symmetry from\n$\\Gamma_{5}$-like at larger diameter to $\\Gamma_{1}$-like at smaller diameter.\nAfter the crossover, the absorption intensity of the band-edge exciton states\nis significantly enhanced. Finally, we find that Vegard's law holds very well\nfor GaInP random alloyed quantum dots down to ultra-small sizes with less than\na hundred atoms. The obtained energy gap bowing parameter of this common-cation\ncompound in QD regime appears positive, size-dependent and much smaller than\nits bulk parentage. The volume deformation, dominating over the charge exchange\nand structure relaxation effects, is mainly responsible for the QD energy gap\nbowing. The present work provides a road map for a variety of electronic and\noptical properties of colloidal QDs in group III-V that can guide spectroscopic\nstudies.",
        "positive": "Bilayer Graphene Growth via a Penetration Mechanism: From both fundamental and technical points of view, a precise control of the\nlayer number of graphene samples is very important. To reach this goal, atomic\nscale mechanisms of multilayer graphene growth on metal surfaces should be\nunderstood. Although it is a geometrically favorable pathway to transport\ncarbon species to interface and then form a new graphene layer there,\npenetration of a graphene overlayer is not a chemically straightforward\nprocess. In this study, the possibility of different active species to\npenetrate a graphene overlayer on Cu(111) surface is investigated based on\nfirst principles calculations. It is found that carbon atom penetration can be\nrealized via an atom exchange process, which leads to a new graphene growth\nmechanism. Based on this result, a bilayer graphene growth protocol is proposed\nto obtain high quality samples. Such a penetration possibility also provides a\ngreat flexibility for designed growth of graphene nanostructures."
    },
    {
        "anchor": "Characterizing oxygen atoms in perovskite and pyrochlore oxides using\n  ADF-STEM at a resolution of a few tens of picometers: We present an aberration corrected scanning transmission electron microscopy\n(ac-STEM) analysis of the perovskite (LaFeO3) and pyrochlore (Yb2Ti2O7 and\nPr2Zr2O7) oxides and demonstrate that both the shape and contrast of visible\natomic columns in annular dark-field (ADF) images are sensitive to the presence\nof nearby atoms of low atomic number (e.g. oxygen). We show that point defects\n(e.g. oxygen vacancies), which are invisible - or difficult to observe due to\nlimited sensitivity - in X-ray and neutron diffraction measurements, are the\norigin of the complex magnetic ground state of pyrochlore oxides. In addition,\nwe present, for the first time, a method by which light atoms can be resolved\nin quantitative ADF-STEM images. Using this method, we resolved oxygen atoms in\nperovskite and pyrochlore oxides.",
        "positive": "Magneto-transport and electronic structures in MoSi$_2$ bulks and thin\n  films with different orientations: We report a comprehensive study of magneto-transport properties in MoSi$_2$\nbulk and thin films. Textured MoSi$_2$ thin films of around 70 nm were\ndeposited on silicon substrates with different orientations. Giant\nmagnetoresistance of 1000% was observed in sintered bulk samples while MoSi$_2$\nsingle crystals exhibit a magnetoresistance (MR) value of 800% at low\ntemperatures. At the low temperatures, the MR of the textured thin films show\nweak anti-localization behaviour owing to the spin orbit coupling effects. Our\nfirst principle calculation show the presence of surface states in this\nmaterial. The resistivity of all the MoSi$_2$ thin films is significantly low\nand nearly independent of the temperature, which is important for electronic\ndevices."
    },
    {
        "anchor": "Wave function of a photoelectron and its collapse in the photoemission\n  process: Based on the first-order perturbation theory, we show that the wave function\nof a photoelectron is a wave packet with the same width as the incident light\npulse. Photoelectron detection measurements revealed that the widths of signal\npulses were much shorter than the light pulse and independent of the origin\n(photoemission or other noises), which is an experimental observation of the\nwave function collapse. Signal pulses of photoelectrons were distributed along\nthe time axis within the same width as the light pulse, consistent with the\ninterpretation of a wave function as a probability distribution.",
        "positive": "Electrochemical Strain Microscopy with Blocking Electrodes: The Role of\n  Electromigration and Diffusion: Electrochemical strains are a ubiquitous feature of solid state ionic devices\nranging from ion batteries and fuel cells to electroresistive and memristive\nmemories. Recently, we proposed a scanning probe microscopy (SPM) based\napproach, referred as electrochemical strain microscopy (ESM), for probing\nlocal ionic flows and electrochemical reactions in solids based on bias-strain\ncoupling. In ESM, the sharp SPM tip concentrates the electric field in a small\n(10-50 nm) region of material, inducing interfacial electrochemical processes\nand ionic flows. The resultant electrochemical strains are determined from\ndynamic surface displacement and provide information on local electrochemical\nfunctionality. Here, we analyze image formation mechanism in ESM for a special\ncase of mixed electronic-ionic conductor with blocking tip electrode, and\ndetermine frequency dependence of response, role of diffusion and\nelectromigration effects, and resolution and detection limits."
    },
    {
        "anchor": "Strain Engineering on the Excitonic Properties of Monolayer GaSe: This paper investigates strain effects on the electronic and optical\nproperties of monolayer GaSe using first-principles calculations. The\ndeformation significantly alters energy dispersion, band gap, and the band edge\nstates of GaSe. The band gap evolution exhibits both linearly and nonlinearly\nwith the strains, and strongly depending on the types of deformation and the\ndirection of the modifications. The external mechanical strains also\nsignificantly tailor the optical properties of GaSe, the exciton binding energy\nis strongly reduced when the tensile strain is applied, while the opposite way\nis true for compressive stress. Moreover, the inhomogeneous strain also induces\nstrong polarization in the absorption spectra. Our calculations demonstrate\nthat the electronic and optical properties of GaSe monolayer can be\nsignificantly tuned by using strain engineering which appears as a promising\nway to design novel optoelectronic devices.",
        "positive": "The comparative defect study on the polymeric transfer of MoS2\n  monolayers: The defect-free transfer of chemical vapour deposition (CVD) grown monolayer\nMoS2 is important for both fabrication of 2D devices and fundamental point of\nview for various studies where substrate effects need to be minimized. Among\nmany transfer techniques, two well-known techniques that use the polymer as\ncarriers are wet-transfer technique and the surface-energy-assisted transfer\ntechnique. In this work, we transferred a single CVD grown monolayer MoS2 by\nthese two transfer methods on a similar substrate, and the intervention of\nstrain and defects in the transfer process is probed by Raman and\nphotoluminescence (PL) spectroscopy, respectively. We found that the\nconventional and commonly used wet transfer technique degraded the monolayer\ndue to KOH contamination. In contrast, monolayers transferred using the\nsurface-energy-assisted transfer method possess structural integrity and\noptical quality on a par with the as-grown MoS2 layers. As compared to the wet\nprocess a strain-free transfer was recorded in the surface-energy-assisted\ntechnique using Raman spectroscopic studies."
    },
    {
        "anchor": "Origin of the two-dimensional electron gas at LaAlO3/SrTiO3 interfaces:\n  The role of oxygen vacancies and electronic reconstruction: The relative importance of atomic defects and electron transfer in explaining\nconductivity at the crystalline LaAlO3/SrTiO3 interface has been a topic of\ndebate. Metallic interfaces with similar electronic properties produced by\namorphous oxide overlayers on SrTiO3 have called in question the original\npolarization catastrophe model. We resolve the issue by a comprehensive\ncomparison of (100)-oriented SrTiO3 substrates with crystalline and amorphous\noverlayers of LaAlO3 of different thicknesses prepared under different oxygen\npressures. For both types of overlayers, there is a critical thickness for the\nappearance of conductivity, but its value is always 4 unit cells (around 1.6\nnm) for the oxygen-annealed crystalline case, whereas in the amorphous case,\nthe critical thickness could be varied in the range 0.5 to 6 nm according to\nthe deposition conditions. Subsequent ion milling of the overlayer restores the\ninsulating state for the oxygen-annealed crystalline heterostructures but not\nfor the amorphous ones. Oxygen post-annealing removes the oxygen vacancies, and\nthe interfaces become insulating in the amorphous case. However, the interfaces\nwith a crystalline overlayer remain conducting with reduced carrier density.\nThese results demonstrate that oxygen vacancies are the dominant source of\nmobile carriers when the LaAlO3 overlayer is amorphous, while both oxygen\nvacancies and polarization catastrophe contribute to the interface conductivity\nin unannealed crystalline LaAlO3/SrTiO3 heterostructures, and the polarization\ncatastrophe alone accounts for the conductivity in oxygen-annealed crystalline\nLaAlO3/SrTiO3 heterostructures. Furthermore, we find that the crystallinity of\nthe LaAlO3 layer is crucial for the polarization catastrophe mechanism in the\ncase of crystalline LaAlO3 overlayers.",
        "positive": "Study of helium irradiation induced hardening in MNHS steel: A recently developed reduced activation ferritic/martensitic steel MNHS was\nirradiated with 200keV He ions to a fluence of 1E21ions/m^2 at 450 celsius\ndegree and 1E20ions/m^2 at 300 celsius degree and 450 celsius degree,\nrespectively. The irradiation hardening of the steel was investigated by\nnanoindentation measurements combined with transmission electron microscopy\n(TEM) analysis. Dispersed barrier-hardening (DBH) model was applied to predict\nthe hardness increments based on TEM analysis. The predicted hardness\nincrements are consistent with the values obtained by nanoindentation tests. It\nis found that dislocation loops and He bubbles are hard barriers against\ndislocation motion and they are the main contributions to He\nirradiation-induced hardening of MNHS steel. The obstacle strength of He\nbubbles is stronger than the obstacle strength of dislocation loops."
    },
    {
        "anchor": "Modeling of cyclic creep in the finite strain range using a nested\n  multiplicative split: A new phenomenological model of cyclic creep is proposed which is suitable\nfor applications involving finite creep deformations of the material. The model\naccounts for the the effect of the transient increase of the creep strain rate\nupon the load reversal. In order to extend the applicability range of the\nmodel, the creep process is fully coupled to the classical Kachanov-Rabonov\ndamage evolution. As a result, the proposed model describes all the three\nstages of creep. Large strain kinematics is described in a geometrically exact\nmanner using the assumption of a nested multiplicative split, originally\nproposed by Lion for finite strain plasticity. The model is thermodynamically\nadmissible, objective, and w-invariant. Implicit time integration of the\nproposed evolution equations is discussed. The corresponding numerical\nalgorithm is implemented into the commercial FEM code MSC.MARC. Using this\ncode, the model is validated using real experimental data on cyclic torsion of\na thick-walled tubular specimen made of the D16T aluminium alloy. The\nnumerically computed stress distribution exhibits a \"skeletal point\" within the\nspecimen.",
        "positive": "Introduction to bulk metallic glass composite and its recent\n  applications: Bulk metallic glass (BMG) materials are hot topics in recent years, not to\nmention BMG matrix composites, which further improve the magnetic and\nmechanical properties of BMG materials. BMG and BMG matrix materials are fast\ndeveloping and promising materials in modern industry due to their\nextraordinary properties such as high strength, low density, excellent\nresistibility to high temperature and corrosion. In this paper, I reviewed\nprocessing and application of several recently developed BMG and BMG matrix\nmaterials."
    },
    {
        "anchor": "In-situ quantitative measurement of electric fields in zinc oxide thin\n  films using electrostatic force microscopy: Zinc oxide (ZnO) is the most important material for the fabrication of modern\nvaristors (variable resistors). It is known that the highly nonlinear\ncurrent-voltage relationship of ZnO varistors is due to effects taking place at\nthe grain boundaries. For an accurate investigation of the mechanism of this\nprocess, techniques are required that allow a direct observation of local\nelectric fields in varistor samples. The objective of this study is to show\nthat an atomic force microscope in a set-up as an electrostatic force\nmicroscope is capable of the in-situ observation and measurement of an applied\nelectric field in samples of ZnO thin films. The technique of Surface Potential\nImaging was used to investigate laterally applied electric fields in this type\nof sample for the first time. The local change of the electric field across the\nsamples was monitored and quantified. It was observed here that the morphology\nof the surface is convoluted into the surface potential images and the\nmagnitude of this effect was quantified by taking surface potential images\nwithout an applied electric field. For the given measurement conditions, a\nheight difference of 80 nm in the topography image resulted in a voltage\ndifference of roughly 66 mV in the surface potential image. A simple model was\nprovided that attributes this observation to the surroundings of the surface\natom closest to the imaging tip.",
        "positive": "Spin-wave-induced lateral temperature gradient in a YIG thin film/GGG\n  system excited in an ESR cavity: Lateral thermal gradient of an yttrium iron garnet (YIG) film under the\nmicrowave application in the cavity of the electron spin resonance system (ESR)\nwas measured at room temperature by fabricating a Cu/Sb thermocouple onto it.\nTo date, thermal transport in YIG films caused by the Damon-Eshbach mode (DEM)\n- the unidirectional spin-wave heat conveyer effect - was demonstrated only by\nthe excitation using coplanar waveguides. Here we show that effect exists even\nunder YIG excitation using the ESR cavity - tool often employed to realize spin\npumping. The temperature difference observed around the ferromagnetic resonance\n(FMR) field under the 4 mW microwave power peaked at 13 mK. The observed\nthermoelectric signal indicates the imbalance of the population between the\nDEMs that propagate near the top and bottom surfaces of the YIG film. We\nattribute the DEM population imbalance to the different magnetic damping near\nthe top and bottom YIG surfaces. Additionally, the spin wave dynamics of the\nsystem were investigated using the micromagnetic simulations. The micromagnetic\nsimulations confirmed the existence of the DEM imbalance in the system with the\nincreased Gilbert damping at one of the YIG interfaces. The reported results\nare indispensable for the quantitative estimation of the electromotive force in\nthe spin-charge conversion experiments using ESR cavities."
    },
    {
        "anchor": "Comment on 3D Penrose Tiling of the Icosahedral Quasicrystalline Phase: A recent arXiv contribution makes the case that the quasicrystallinephase is\ndue to twinning, albeit with a different twinning scheme than thatpresented by\nPauling. It appears to us that this approach, though novel, hasno validity.",
        "positive": "Two-dimensional quantum oscillations of the conductance at LaAlO3/SrTiO3\n  interfaces: We report on a study of magnetotransport in LaAlO3/SrTiO3 interfaces\ncharacterized by mobilities of the order of several thousands cm$^{2}$/Vs. We\nobserve Shubnikov-de Haas oscillations that indicate a two-dimensional\ncharacter of the Fermi surface. The frequency of the oscillations signals a\nmultiple sub-bands occupation in the quantum well or a multiple valley\nconfiguration. From the temperature dependence of the oscillation amplitude we\nextract an effective carrier mass $m^{*}\\simeq1.45$\\,$m_{e}$. An electric field\napplied in the back-gate geometry increases the mobility, the carrier density\nand the oscillation frequency."
    },
    {
        "anchor": "Interplay of Physically Different Properties Leading to Challenges in\n  Separating Lanthanide Cations -- an Ab Initio Molecular Dynamics and\n  Experimental Study: The lanthanide elements have well-documented similarities in their chemical\nbehavior, which makes the valuable trivalent lanthanide cations (Ln(III))\nparticularly difficult to separate from each other in water. In this work, we\napply ab initio molecular dynamics simulations to compare the free energies\n(Delta G(ads)) associated with the adsorption of lanthanide cations to silica\nsurfaces at a pH condition where SiO- groups are present. The predicted Delta\nG(ads) for lutetium (Lu(III)) and europium (Eu(III)) are similar within\nstatistical uncertainties; this is in qualitative agreement with our batch\nadsorption measurements on silica. This finding is remarkable because the two\ncations exhibit hydration free energies (Delta G(hyd}) that differ by >2 eV,\ndifferent hydration numbers, and different hydrolysis behavior far from silica\nsurfaces. We observe that the similarity in Lu(III) and Eu(III) Delta G(ads) is\nthe result of a delicate cancellation between the difference in Eu(III) and\nLu(III) hydration (Delta G(hyd})), and their difference in binding energies to\nsilica. We propose that disrupting this cancellation at the two end points,\neither for adsorbed or completely desorbed lanthanides (e.g., via\nnanoconfinment or mixed solvents), will lead to effective Ln separation.",
        "positive": "Raman Spectral Indicators of Catalyst Decoupling for Transfer of CVD\n  Grown 2D Materials: Through a combination of monitoring the Raman spectral characteristics of 2D\nmaterials grown on copper catalyst layers, and wafer scale automated detection\nof the fraction of transferred material, we reproducibly achieve transfers with\nover 97.5% monolayer hexagonal boron nitride and 99.7% monolayer graphene\ncoverage, for up to 300 mm diameter wafers. We find a strong correlation\nbetween the transfer coverage obtained for graphene and the emergence of a\nlower wavenumber 2D- peak component, with the concurrent disappearance of the\nhigher wavenumber 2D+ peak component during oxidation of the catalyst surface.\nThe 2D peak characteristics can therefore act as an unambiguous predictor of\nthe success of the transfer. The combined monitoring and transfer process\npresented here is highly scalable and amenable for roll-to-roll processing."
    },
    {
        "anchor": "Anomalous thermal oxidation of gadolinium thin films deposited on\n  silicon by high pressure sputtering: Thin gadolinium metallic layers were deposited by high-pressure sputtering in\npure Ar atmosphere. Subsequently, in situ thermal oxidation was performed at\ntemperatures ranging from 150 to 750 $^\\circ$C. At an oxidation temperature of\n500 $^\\circ$C the films show a transition from monoclinic structure to a\nmixture of monoclinic and cubic. Regrowth of interfacial SiO$_x$ is observed as\ntemperature is increased, up to 1.6 nm for 750 $^\\circ$C. This temperature\nyields the lowest interface trap density, 4e10 eV$^{-1}$ cm$^{-2}$, but the\neffective permittivity of the resulting dielectric is only 7.4. The reason of\nthis low value is found on the oxidation mechanism, which yields a surface with\nlocated bumps. These bumps increase the average thickness, thus reducing the\ncapacitance and therefore the calculated permittivity.",
        "positive": "Anomalous binding of Fe atoms in chromium: Binding of 57Fe atoms in a metallic chromium was investigated in a Cr-Fe\nalloy, containing less than 0.1 at% Fe enriched to ~95 % in 57Fe isotope, using\n57Fe-site Mossbauer spectroscopy. The binding force was derived from the Debye\ntemperature, T_D, that, in turn, was calculated from the temperature dependence\nof the central shift of the Mossbauer spectra recorded in the range of 80 to\n330 K. Following a temperature dependence of the line width that shows a\nminimum at ~155 K, two temperature intervals were considered: a low temperature\none (LT) ranging from 80 to 155 K, and the T_D - value of 292 (12) K or 279\n(34) K, and a high temperature one (HT) ranging from 155 to 330 K with the T_D\n- value of 399 (15) or 399 (25) K, depending on the fitting procedure. The\ncorresponding values of the harmonic force (spring) constant are: 35.4 N/m and\n66.1 N/m or 33.8 N/m and 66.1 N/m for the LT and HT, respectively. This means\nthat in the HT range the binding force of 57Fe atoms by the Cr matrix is by a\nfactor of ~1.9 - 2 stronger than that in the LT range. This anomaly is possibly\nrelated with a different polarization of the spin-density waves in the LT and\nHT \"phases\"."
    },
    {
        "anchor": "Strong spatial dispersion in wire media in the very large wavelength\n  limit: It is found that there exist composite media that exhibit strong spatial\ndispersion even in the very large wavelength limit. This follows from the study\nof lattices of ideally conducting parallel thin wires (wire media). In fact,\nour analysis reveals that the description of this medium by means of a local\ndispersive uniaxial dielectric tensor is not complete, leading to unphysical\nresults for the propagation of electromagnetic waves at any frequencies. Since\nnon--local constitutive relations have been usually considered in the past as a\nsecond order approximation, meaningful in the short wavelength limit, the\naforementioned result presents a relevant theoretical interest. In addition,\nsince such wire media have been recently used as a constituent of some discrete\nartificial media (or metamaterials), the reported results open the question of\nthe relevance of the spatial dispersion in the characterization of these\nartificial media.",
        "positive": "Hydrogen trapping and embrittlement in high-strength Al-alloys: Ever more stringent regulations on greenhouse gas emissions from\ntransportation motivate efforts to revisit materials used for vehicles.\nHigh-strength Al-alloys often used in aircrafts could help reduce the weight of\nautomobiles, but are susceptible to environmental degradation. Hydrogen (H)\n\"embrittlement\" is often pointed as the main culprit, however, the mechanisms\nunderpinning failure are elusive: atomic-scale analysis of H inside an alloy\nremains a challenge, and this prevents deploying alloy design strategies to\nenhance the materials' durability. Here we successfully performed near-atomic\nscale analysis of H trapped in second-phase particles and at grain boundaries\nin a high-strength 7xxx Al-alloy. We used these observations to guide atomistic\nab-initio calculations which show that the co-segregation of alloying elements\nand H favours grain boundary decohesion, while the strong partitioning of H\ninto the second-phases removes solute H from the matrix, hence preventing\nH-embrittlement. Our insights further advance the mechanistic understanding of\nH-assisted embrittlement in Al-alloys, emphasizing the role of H-traps in\nretarding cracking and guiding new alloy design."
    },
    {
        "anchor": "Terahertz spectroscopy for all-optical spintronic characterization of\n  the spin-Hall-effect metals Pt, W and Cu$_{80}$Ir$_{20}$: Identifying materials with an efficient spin-to-charge conversion is crucial\nfor future spintronic applications. The spin Hall effect is a central mechanism\nas it allows for the interconversion of spin and charge currents. Spintronic\nmaterial research aims at maximizing its efficiency, quantified by the spin\nHall angle $\\Theta_{\\textrm{SH}}$ and the spin-current relaxation length\n$\\lambda_{\\textrm{rel}}$. We develop an all-optical method with large sample\nthroughput that allows us to extract $\\Theta_{\\textrm{SH}}$ and\n$\\lambda_{\\textrm{rel}}$. Employing terahertz spectroscopy, we characterize\nmagnetic metallic heterostructures involving Pt, W and Cu$_{80}$Ir$_{20}$ in\nterms of their optical and spintronic properties. We furthermore find\nindications that the interface plays a minor role for the spin-current\ntransmission. Our analytical model is validated by the good agreement with\nliterature DC values. These findings establish terahertz emission spectroscopy\nas a reliable tool complementing the spintronics workbench.",
        "positive": "Linearized force constants method for lattice dynamics in mixed\n  semiconductors: A simple and accurate method of calculating phonon spectra in mixed\nsemiconductors alloys, on the basis of preliminarily (from first principles)\nrelaxed atomic structure, is proposed and tested for (Zn,Be)Se and (Ga,In)As\nsolid solutions. The method uses an observation that the interatomic force\nconstants, calculated ab initio for a number of microscopic configurations in\nthe systems cited, show a clear linear variation of the main (diagonal) values\nof the interatomic force constants with the corresponding bond length. We\nformulate simple rules about how to recover the individual 3x3 subblocks of the\nforce constants matrix in their local (bonds-related) coordinate systems and\nhow to transform them into a global (crystal cell-related) coordinate system.\nTest calculations done for 64-atom supercells representing different\nconcentrations of (Zn,Be)Se and (Ga,In)As show that the phonon frequencies and\ncompositions of eigenvectors are faithfully reproduced in a linearized force\nconstants calculation, as compared to true ab initio calculations."
    },
    {
        "anchor": "Change in the Crystallization Features of Supercooled Liquid Metal with\n  an Increase in the Supercooling Level: The process of homogeneous crystal nucleation has been considered in a model\nliquid, where the interparticle interaction is described by a short-range\nspherical oscillatory potential. Mechanisms of initiating structural ordering\nin the liquid at various supercooling levels, including those corresponding to\nan amorphous state, have been determined. The sizes and shapes of formed\ncrystal grains have been estimated statistically. The results indicate that the\nmechanisms of nucleation occurs throughout the entire considered temperature\nrange. The crystallization of the system at low supercooling levels occurs\nthrough a mononuclear scenario. A high concentration of crystal nuclei formed\nat high supercooling levels (i.e., at temperatures comparable to and below the\nglass transition temperature $T_g$) creates the semblance of the presence of\nbranched structures, which is sometimes erroneously interpreted as a signature\nof phase separation. The temperature dependence of the maximum concentration of\ncrystal grains demonstrates two regimes the transition between which occurs at\na temperature comparable to the glass transition temperature $T_g$.",
        "positive": "Robust half-metallicity and metamagnetism in Fe_{x}Co_{1-x}S_{2}: The Fe_{x}Co_{1-x}S_{2} system is predicted, on the basis of density\nfunctional calculations, to be a half metal for a large range of\nconcentrations. Unlike most known half metals, the half metallicity in this\nsystem should be very stable with respect to crystallographic disorder and\nother types of defects. The endmember of the series, CoS_{2}, is not a half\nmetal, but exhibits interesting and unusual magnetic properties which can,\nhowever, be reasonably well understood within the density functional theory,\nparticularly with the help of the extended Stoner model. Calculations suggest\nstrong electron-phonon and electron-magnon coupling in the system, and probably\na bad metal behavior at high temperatures."
    },
    {
        "anchor": "Structure and Strength of Dislocation Junctions: An Atomic Level\n  Analysis: The quasicontinuum method is used to simulate three-dimensional\nLomer-Cottrell junctions both in the absence and in the presence of an applied\nstress. The simulations show that this type of junction is destroyed by an\nunzipping mechanism in which the dislocations that form the junction are\ngradually pulled apart along the junction segment. The calculated critical\nstress needed for breaking the junction is comparable to that predicted by line\ntension models. The simulations also demonstrate a strong influence of the\ninitial dislocation line directions on the breaking mechanism, an effect that\nis neglected in the macroscopic treatment of the hardening effect of junctions.",
        "positive": "Multi-Mode Front Lens for Momentum Microscopy: Part II Experiments: We have experimentally demonstrated different operating modes for the front\nlenses of the momentum microscopes described in Part I. Measurements at\nenergies from vacuum UV at a high-harmonic generation (HHG)-based source to the\nsoft and hard X-ray range at a synchrotron facility validated the results of\ntheoretical ray-tracing calculations. The key element is a ring electrode\nconcentric with the extractor electrode, which can tailor the field in the gap.\nFirst, the gap-lens-assisted extractor mode reduces the field strength at the\nsample while mitigating image aberrations. This mode gave good results in all\nspectral ranges. Secondly, by compensating the field at the sample surface with\na negative voltage at the ring electrode we can operate in zero-field mode,\nwhich is beneficial for operando experiments. Finally, higher negative voltages\nestablish the repeller mode, which removes all slow electrons below a certain\nkinetic energy to eliminate the primary contribution to the space-charge\ninteraction in pump-probe experiments. The switch from extractor to repeller\nmode is associated with a reduction in the k-field-of-view (10-20 % at\nhard-X-ray energies, increasing to ~50% at low energies). Real-space imaging\nalso benefits from the new lens modes as confirmed by ToF-XPEEM imaging with\n650 nm resolution."
    },
    {
        "anchor": "Inducing and Optimizing Magnetism in Graphene Nanomesh: Using first-principles calculations, we explore the electronic and magnetic\nproperties of graphene nanomesh (GNM), a regular network of large vacancies,\nproduced either by lithography or nanoimprint. When removing an equal number of\nA and B sites of the graphene bipartite lattice, the nanomesh made mostly of\nzigzag (armchair) type edges exhibit antiferromagnetic (spin unpolarized)\nstates. In contrast, in situation of sublattice symmetry breaking, stable\nferri(o)magnetic states are obtained. For hydrogen-passivated nanomesh, the\nformation energy is dramatically decreased, and ground state is found to\nstrongly depend on the vacancies shape and size. For triangular shaped holes,\nthe obtained net magnetic moments increase with the number difference of\nremoved A and B sites in agreement with Lieb's theorem for even A+B. For odd\nA+B triangular meshes and all cases of non-triangular nanomeshes including the\none with even A+B, Lieb's theorem does not hold anymore which can be partially\nattributed to introduction of armchair edges. In addition, large triangular\nshaped GNM could be as robust as non-triangular GNMs, providing possible\nsolution to overcome one of crucial challenges for the sp-magnetism. Finally,\nsignificant exchange splitting values as large as $\\sim 0.5$ eV can be obtained\nfor highly asymmetric structures evidencing the potential of GNM for room\ntemperature carbon based spintronics. These results demonstrate that a turn\nfrom 0-dimensional graphene nanoflakes throughout 1-dimensional graphene\nnanoribbons with zigzag edges to GNM breaks localization of unpaired electrons\nand provides deviation from the rules based on Lieb's theorem. Such\ndelocalization of the electrons leads the switch of the ground state of system\nfrom antiferromagnetic narrow gap insulator discussed for graphene nanoribons\nto ferromagnetic or nonmagnetic metal.",
        "positive": "Elastic vs. plastic strain relaxation in coalesced GaN nanowires: an\n  x-ray diffraction study: The coalescence in dense arrays of spontaneously formed GaN nanowires\nproceeds by bundling: adjacent nanowires bend and merge at their top, thus\nreducing their surface energy at the expense of the elastic energy of bending.\nWe give a theoretical description of the energetics of this bundling process.\nThe bending energy is shown to be substantially reduced by the creation of\ndislocations at the coalescence joints. A comparison of experimental and\ncalculated x-ray diffraction profiles from ensembles of bundled nanowires\ndemonstrates that a large part of the bending energy is indeed relaxed by\nplastic deformation. The residual bending manifests itself by extended tails of\nthe diffraction profiles."
    },
    {
        "anchor": "Bleaching of optical activity induced by UV Laser exposure in natural\n  silica: We report experimental data on two types of natural silica, differing for\ntheir OH content, irradiated with UV photons (4.66 eV) from a pulsed Nd:YAG\nlaser. Irradiation induces a reduction of the absorption band at 5.12eV and of\nthe associated emissions at 3.14eV and 4.28eV, ascribed to twofold coordinated\nGe (=Ge'') centers pre-existing in our samples. The bleaching is mainly due to\nthe post-irradiation conversion of =Ge'' into the paramagnetic H(II) center via\ntrapping of a H atom. Comparison with literature data points out the\npeculiarities of silica with a low Ge concentration as regards UV induced\ntransformations.",
        "positive": "Mesoscopic study on historic masonry: This paper presents a comprehensive approach to the evaluation of macroscopic\nmaterial parameters for natural stone and quarry masonry. To that end, a\nreliable non-linear material model on a meso-scale is developed to cover the\nrandom arrangement of stone blocks and quasi-brittle behaviour of both basic\ncomponents, as well as the impaired cohesion and tensile strength on the\ninterface between the blocks and mortar joints. The paper thus interrelates the\nfollowing three problems: (i) definition of a suitable periodic unit cell (PUC)\nrepresenting a particular masonry structure; (ii) derivation of material\nparameters of individual constituents either experimentally or running a mixed\nnumerical-experimental problem; (iii) assessment of the macroscopic material\nparameters including the tensile and compressive strengths and fracture energy."
    },
    {
        "anchor": "Layer-dependent electronic structures and magnetic ground states of\n  polar-polar $\\rm{LaVO_3/KTaO_3}$ (001) interfaces: Employing a first-principles and model Hamiltonian approach, we work out the\nelectronic properties of polar-polar LaVO$_3$/KTaO$_3$ (LVO/KTO, 001)\nhetero-interfaces, considering configurations with up to six layers of KTO and\nfive layers of LVO. Our computational analyses indicate the existence of\nmultiple Lifshitz transitions (LT) within the $t_{2g}$ bands, potentially\nmanifesting in elevated thermal conductivity and Seebeck coefficient. The\nLifshitz transitions can be fine-tuned by adjusting the number of LVO layers or\napplying gate voltage. Contrary to experimental report, the spin-orbit coupling\nis found to be negligible, originating solely from the Ta $5d_{xy}$-derived\nband of KTO, while the 5$d_{xz}$ and 5$d_{yz}$ bands are considerably away from\nthe Fermi level and LVO overlayers playing no role in it. The magnetic\nproperties of the interfaces, due to Vanadium ions, exhibit a pronounced\nsensitivity to the number of LVO and KTO layers. Spin-polarized density of\nstates reveals that the interfaces featuring ferromagnetic (FM) ground states\nare \\textit{half-metallic}. The small energy differences between\nantiferromagnetic (AFM) and ferromagnetic (FM) configurations suggest a\npotential coexistence of competing AFM and FM ground states within these\ninterfaces. Moreover, we find that an insulator to metal transition at the\ninterface requires a distinct number of LVO layers: a half-metallic FM state\nappears for two and more LVO layers and a metallic AFM state is found from four\nLVO layers onwards. The experimentally observed critical thickness for\nmetallicity, therefore, requires consideration of the magnetic interactions.\nAdditionally, we observe that the oxygen-mediated superexchange mechanism\ngoverns the behavior of AFM insulators, whereas direct exchange is responsible\nfor the metallic and \\textit{half-metallic} traits.",
        "positive": "Multi-component low and high entropy metallic coatings synthesized by\n  pulsed magnetron sputtering: This paper presents the findings of the synthesis of multicomponent (Al, W,\nNi, Ti, Nb) alloy coatings from mosaic targets. For the study, a pulsed\nmagnetron sputtering method was employed under different plasma generation\nconditions: modulation frequency (10 Hz and 1000 Hz), and power (600 W and 1000\nW). The processes achieved two types of alloy coatings, high entropy and\nclassical alloys. After the deposition processes, scanning electron microscopy,\nX-ray diffraction, and energy-dispersive X-ray spectroscopy techniques were\nemployed to find the morphology, thickness, and chemical and phase compositions\nof the coatings. Nanohardness and its related parameters, namely H3.Er2, H.E,\nand 1.Er2H ratios, were measured. An annealing treatment was performed to\nestimate the stability range for the selected coatings. The results indicated\nthe formation of as-deposited coatings exhibiting an amorphous structure as a\nsingle-phase solid solution. The process parameters had an influence on the\nresulting morphology-a dense and homogenous as well as a columnar morphology,\nwas obtained. The study compared the properties of high-entropy alloy (HEA)\ncoatings and classical alloy coatings concerning their structure and chemical\nand phase composition. It was found that the change of frequency modulation and\nthe post-annealing process contributed to the increase in the hardness of the\nmaterial in the case of HEA coatings."
    },
    {
        "anchor": "Ultra-low glassy thermal conductivity and controllable, promising\n  thermoelectric properties in crystalline o-CsCu5S3: We thoroughly investigate the microscopic mechanisms of the thermal transport\nin orthorhombic \\textit{o}-CsCu$_5$S$_3$ by integrating the\nfirst-principles-based self-consistent phonon calculations (SCP) with the\nlinearized Wigner transport equation (LWTE). Our methodology takes into account\ncontributions to phonon energy shifts and phonon scattering rates from both\nthree- and four-phonon processes. Additionally, it incorporates the\noff-diagonal terms of heat flux operators to calculate the total thermal\nconductivity. The predicted $\\kappa_\\mathrm{L}$ with an extremely weak\ntemperature dependence following $\\sim T^{-0.33}$, in good agreement with\nexperimental values along with the parallel to the Bridgman growth direction.\nSuch nonstandard temperature dependence of $\\kappa_\\mathrm{L}$ can be traced\nback to the dual particlelike-wavelike behavior exhibited by thermal phonons.\nSpecifically, the coexistence of the stochastic oscillation of Cs atoms and\nmetavalent bonding among interlayer Cu-S atoms limits the particle-like phonon\npropagation and enhances the wave-like tunneling of phonons. Simultaneously,\nthe electrical transport properties are determined by employing a precise\nmomentum relaxation-time approximation (MRTA) within the framework of the\nlinearized Boltzmann transport equation (LBTE). By properly adjusting the\ncarrier concentration, excellent thermoelectric performance is achieved, with a\nmaximum thermoelectric conversion efficiency of 18.4$\\%$ observed at 800 K in\n\\textit{p}-type \\textit{o}-CsCu$_5$S$_3$.} Our work not only elucidates the\nanomalous thermal transport behavior in the copper-based chalcogenide\n\\textit{o}-CsCu$_5$S$_3$ but also provides insights for manipulating its\nthermal and electronic properties for potential thermoelectric applications.",
        "positive": "Exciton band structure of V$_2$O$_5$: Excitonic effects due to the correlation of electrons and holes in excited\nstates of matter dominate the optical spectra of many interesting materials.\nThey are usually studied in the long-wavelength limit. Here we investigate\nexcitons at non-vanishing momentum transfer, corresponding to shorter\nwavelengths. We calculate the exciton dispersion in the prototypical layered\noxide V$_2$O$_5$ by solving the Bethe-Salpeter equation of many-body\nperturbation theory. We discuss the change of excitation energy and intensity\nas a function of wavevector for bright and dark excitons, respectively, and we\nanalyze the origin of the excitons along their dispersion. We highlight the\nimportant role of the electron-hole exchange with its impact on the exciton\ndispersion, the singlet-triplet splitting and the difference between the\nimaginary part of the macroscopic dielectric function and the loss function."
    },
    {
        "anchor": "Electric field induced metallic behavior in thin crystals of\n  ferroelectric \u03b1-In2Se3: Ferroelectric semiconductor field effect transistors (FeSmFETs), which employ\nferroelectric semiconducting thin crystals of {\\alpha}-In2Se3 as the channel\nmaterial as opposed to the gate dielectric in conventional ferroelectric FETs\n(FeFETs) were prepared and measured from room to the liquid-helium\ntemperatures. These FeSmFETs were found to yield evidence for the reorientation\nof the electrical polarization and an electric field induced metallic state in\n{\\alpha}-In2Se3. Our findings suggest that FeSmFETs can serve as a platform for\nthe fundamental study of ferroelectric metals as well as the exploration of the\nintegration of data storage and logic operations in the same device.",
        "positive": "Doping nature of native defects in 1T-TiSe2: The transition metal dichalcogenide 1T-TiSe2 is a quasi two-dimensional\nlayered material with a charge density wave (CDW) transition temperature of\nTCDW 200 K. Self-doping effects for crystals grown at different temperatures\nintroduce structural defects, modify the temperature dependent resistivity and\nstrongly perturbate the CDW phase. Here we study the structural and doping\nnature of such native defects combining scanning tunneling\nmicroscopy/spectroscopy and ab initio calculations. The dominant native single\natom dopants we identify in our single crystals are intercalated Ti atoms, Se\nvacancies and Se substitutions by residual iodine and oxygen."
    },
    {
        "anchor": "Direct observation of correlation time of dynamic nuclear polarization\n  in single quantum dots: The spin interaction between an electron and nuclei was investigated\noptically in a single self-assembled InAlAs quantum dot (QD). In spin dynamics,\nthe correlation time of the coupled electron-nuclear spin system and the\nelectron spin relaxation time play a crucial role. We examined on a positively\ncharged exciton in a QD to evaluate these key time constants directly via the\ntemporal evolution measurements of the Overhauser shift and the degree of\ncircular polarization. In addition, the validity of our used spin dynamics\nmodel was discussed in the context of the experimentally obtained key\nparameters.",
        "positive": "Nonvolatile Electric Field Control of Thermal Magnons in the Absence of\n  an Applied Magnetic Field: Spin transport through magnetic insulators has been demonstrated in a variety\nof materials and is an emerging pathway for next-generation spin-based\ncomputing. To modulate spin transport in these systems, one typically applies a\nsufficiently strong magnetic field to allow for deterministic control of\nmagnetic order. Here, we make use of the well-known multiferroic\nmagnetoelectric, BiFeO3, to demonstrate non-volatile, hysteretic,\nelectric-field control of thermally excited magnon current in the absence of an\napplied magnetic field. These findings are an important step toward\nmagnon-based devices, where electric-field-only control is highly desirable."
    },
    {
        "anchor": "Tuning the multiferroic mechanisms of TbMnO3 by epitaxial strain: A current challenge in the field of magnetoelectric multiferroics is to\nidentify systems that allow a controlled tuning of states displaying distinct\nmagnetoelectric responses. Here we show that the multiferroic ground state of\nthe archetypal multiferroic TbMnO3 is dramatically modified by epitaxial\nstrain. Neutron diffraction reveals that in highly strained films the magnetic\norder changes from the bulk-like incommensurate bc-cycloidal structure to\ncommensurate magnetic order. Concomitant with the modification of the magnetic\nground state, optical second-harmonic generation (SHG) and electric\nmeasurements show an enormous increase of the ferroelectric polarization, and a\nchange in its direction from along the c- to the a-axis. Our results suggest\nthat the drastic change of multiferroic properties results from a switch of the\nspin-current magnetoelectric coupling in bulk TbMnO3 to symmetric\nmagnetostriction in epitaxially-strained TbMnO3. These findings experimentally\ndemonstrate that epitaxial strain can be used to control single-phase\nspin-driven multiferroic states.",
        "positive": "Magnetization switching in polycrystalline Mn3Sn thin film induced by\n  self-generated spin-polarized current: Electrical manipulation of spins is essential to design state-of-the-art\nspintronic devices and commonly relies on the spin current injected from a\nsecond heavy-metal material. The fact that chiral antiferromagnets produce spin\ncurrent inspires us to explore the magnetization switching of chiral spins\nusing self-generated spin torque. Here, we demonstrate the electric switching\nof noncollinear antiferromagnetic state in Mn3Sn by observing a crossover from\nconventional spin-orbit torque to the self-generated spin torque when\nincreasing the MgO thickness in Ta/MgO/Mn3Sn polycrystalline films. The spin\ncurrent injection from the Ta layer can be controlled and even blocked by\nvarying the MgO thickness, but the switching sustains even at a large MgO\nthickness. Furthermore, the switching polarity reverses when the MgO thickness\nexceeds around 3 nm, which cannot be explained by the spin-orbit torque\nscenario due to spin current injection from the Ta layer. Evident\ncurrent-induced switching is also observed in MgO/Mn3Sn and Ti/Mn3Sn bilayers,\nwhere external injection of spin Hall current to Mn3Sn is negligible. The\ninter-grain spin-transfer torque induced by spin-polarized current explains the\nexperimental observations. Our findings provide an alternative pathway for\nelectrical manipulation of non-collinear antiferromagnetic state without\nresorting to the conventional bilayer structure."
    },
    {
        "anchor": "Direct and indirect electrocaloric measurements using multilayer\n  capacitors: We report the discovery of serendipitous electrocaloric effects in commercial\nmultilayer capacitors based on ferroelectric BaTiO3. Direct thermometry records\n~0.5 K changes due to 300 kV cm-1, over a wide range of temperatures near and\nabove room temperature. Similar results are obtained indirectly, via\nthermodynamic analysis of ferroelectric hysteresis loops. We compare and\ncontrast these two results. Optimised electrocaloric multilayer capacitors\ncould find applications in future cooling technologies.",
        "positive": "sp$^{2}$/sp$^{3}$ bonding controlling mechanism at the\n  $\u03b1$-Al$_{2}$O$_{3}|$graphene interface: First-principles calculations reported here illuminate the effects of the\ninterfacial properties of $\\alpha$-Al$_{2}$O$_{3}$ and graphene, with emphasis\non the structural and electronic properties. Various contact interfaces and\ndifferent $\\alpha$-Al$_{2}$O$_{3}$ surface terminations are considered with on\nand slightly-off stoichiometric aluminium oxide. We show that depending on\nwhether aluminium or oxygen is in contact with graphene, an $sp^{3}$ structural\ndeformation and spontaneous spin-polarization may occur next to the interface\ncontact. Interestingly, some cases cause a $p$-type doping in the graphene band\nstructure, depending on the initial $\\alpha$-Al$_{2}$O$_{3}$ geometry placed on\ngraphene. The importance of leaving the surface dangling bonds of alumina\nsaturated or not is also highlighted, and we show that it might be a control\nmechanism for opening a gap in graphene by the influence of the $sp^{3}$ bond\nbetween oxygen and carbon atoms at the interface. We discuss the potential of\nutilizing this sensitivity for practical applications."
    },
    {
        "anchor": "Increasing the mobility and power-electronics figure of merit of AlGaN\n  with atomically thin AlN/GaN digital-alloy superlattices: Alloy scattering in random AlGaN alloys drastically reduces the electron\nmobility and therefore the power-electronics figure of merit. As a result, Al\ncompositions greater than 75% are required to obtain even a two-fold increase\nof the Baliga figure of merit compared to GaN. However, beyond approximately\n80% Al composition, donors in AlGaN undergo the DX transition which makes\nimpurity doping increasingly more difficult. Moreover, the contact resistance\nincreases exponentially with increasing Al content, and integration with\ndielectrics becomes difficult due to the upward shift of the conduction band.\nAtomically thin superlattices of AlN and GaN, also known as digital alloys, are\nknown to grow experimentally under appropriate growth conditions. These\nchemically ordered nanostructures could offer significantly enhanced figure of\nmerit compared to their random-alloy counterparts due to the absence of alloy\nscattering, as well as better integration with contact metals and dielectrics.\nIn this work, we investigate the electronic structure and phonon-limited\nelectron mobility of atomically thin AlN/GaN digital-alloy superlattices using\nfirst-principles calculations based on density-functional and many-body\nperturbation theory. The band gap of the atomically thin superlattices reaches\n4.8 eV, and the in-plane (out-of-plane) mobility is 369 (452) cm$^2$ V$^{-1}$\ns$^{-1}$. Using the modified Baliga figure of merit that accounts for the\ndopant ionization energy, we demonstrate that atomically thin AlN/GaN\nsuperlattices with a monolayer sublattice periodicity have the highest modified\nBaliga figure of merit among several technologically relevant ultra-wide\nband-gap materials, including random AlGaN, $\\beta$-Ga$_{2}$O$_{3}$, cBN, and\ndiamond.",
        "positive": "Low temperature properties of whispering gallery modes in isotopically\n  pure silicon 28: Whispering Gallery (WG) mode resonators have been machined from a boule of\nsingle-crystal isotopically pure silicon-28. Before machining, the as-grown rod\nwas measured in a cavity, with the best Bragg confined modes exhibiting\nmicrowave $Q$-factors on the order of a million for frequencies between 10 and\n15 GHz. After machining the rod into smaller cylindrical WG mode resonators,\nthe frequencies of the fundamental mode families were used to determine the\nrelative permittivity of the material to be $11.488\\pm0.024$ near 4 K, with the\nprecision limited only by the dimensional accuracy of the resonator. However,\nthe Q-factors were degraded by the machining to below $4\\times10^4$. Raman\nspectroscopy was used to optimize post-machining surface treatments to restore\nhigh $Q$-factors. This is an enabling step for the use of such resonators for\nhybrid quantum systems and frequency conversion applications, as silicon-28\nalso has very low phonon losses, can host very narrow linewidth spin ensembles\nand is a material commonly used in optical applications."
    },
    {
        "anchor": "Nonlinear phonon Hall effects in ferroelectrics: its existence and\n  non-volatile electrical control: Nonlinear Hall effects have been previously investigated in\nnon-centrosymmetric systems for electronic systems. However, they only exist in\nmetallic systems and are not compatible with ferroelectrics since these latter\nare insulators, hence limiting their applications. On the other hand,\nferroelectrics naturally break inversion symmetry and can induce a non-zero\nBerry curvature. Here, we show that a non-volatile electric-field control of\nheat current can be realized in ferroelectrics through the nonlinear phonon\nHall effects. More precisely, based on Boltzmann equation under the\nrelaxation-time approximation, we derive the equation for nonlinear phonon Hall\neffects, and further show that the behaviors of nonlinear phonon (Boson) Hall\neffects are very different from nonlinear Hall effects for electrons (Fermion).\nOur work provides a route for electric-field control of thermal Hall current in\nferroelectrics.",
        "positive": "First-principles study on the stability and electronic structure of\n  monolayer GaSe with trigonal-antiprismatic structure: The structural stability and electronic states of GaSe monolayer with\ntrigonal-antiprismatic (AP) structure, which is a recently discovered new\npolymorph, were studied by first-principles calculations. The AP phase GaSe\nmonolayer was found stable, and the differences in energy and lattice constant\nwere small when compared to those calculated for a GaSe monolayer with\nconventional trigonal-prismatic (P) structure which was found to be the ground\nstate. Moreover, it was revealed that the relative stability of P phase and AP\nphase GaSe monolayers reverses under tensile strain. These calculation results\nprovide insight into the formation mechanism of AP phase GaSe monolayers in\nepitaxially-grown GaSe thin films."
    },
    {
        "anchor": "Impact of Spin Wave Dispersion on Surface Acoustic Wave Velocity: The dependence of the velocity of surface acoustic wave (SAW) as a function\nof an external applied magnetic field is investigated in a Fe thin film\nepitaxially grown on a piezoelectric GaAs substrate. The SAW velocity is\nobserved to strongly depend on both the amplitude and direction of the magnetic\nfield. To interpret the experimental data a phenomenological approach to the\nrelative change in SAW velocity is implemented. We find that the experimental\nvelocity variation can be well reproduced provided that the spin wave\ndispersion is taken into account. The validity of this phenomenological model\nis attested by the comparison with a quasi-exact magnetoelastic one.",
        "positive": "The nonlocal correlation: A key to the solution of the CO adsorption\n  puzzle: We study the chemisorption of CO molecule into sites of different\ncoordination on (111) surfaces of late 4d and 5d transition metals. In an\nattempt to solve the well-known CO adsorption puzzle we have applied the\nrelatively new vdW-DF theory of nonlocal correlation. The application of the\nvdW-DF functional in all considered cases improves or completely solves the\ndiscrepancies of the adsorption site preference and improves the value of the\nadsorption energy. By introducing a cutoff distance for nonlocal interaction we\npinpoint the length scale at which the correlation plays a major role in the\nsystems considered."
    },
    {
        "anchor": "Thermal fracture as a framework for quasi-static crack propagation: We address analytically and numerically the problem of crack path prediction\nin the model system of a crack propagating under thermal loading. We show that\none can explain the instability from a straight to a wavy crack propagation by\nusing only the principle of local symmetry and the Griffith criterion. We then\nargue that the calculations of the stress intensity factors can be combined\nwith the standard crack propagation criteria to obtain the evolution equation\nfor the crack tip within any loading configuration. The theoretical results of\nthe thermal crack problem agree with the numerical simulations we performed\nusing a phase field model. Moreover, it turns out that the phase-field model\nallows to clarify the nature of the transition between straight and oscillatory\ncracks which is shown to be supercritical.",
        "positive": "What is missing in autonomous discovery: Open challenges for the\n  community: Self-driving labs (SDLs) leverage combinations of artificial intelligence,\nautomation, and advanced computing to accelerate scientific discovery. The\npromise of this field has given rise to a rich community of passionate\nscientists, engineers, and social scientists, as evidenced by the development\nof the Acceleration Consortium and recent Accelerate Conference. Despite its\nstrengths, this rapidly developing field presents numerous opportunities for\ngrowth, challenges to overcome, and potential risks of which to remain aware.\nThis community perspective builds on a discourse instantiated during the first\nAccelerate Conference, and looks to the future of self-driving labs with a\ntempered optimism. Incorporating input from academia, government, and industry,\nwe briefly describe the current status of self-driving labs, then turn our\nattention to barriers, opportunities, and a vision for what is possible. Our\nfield is delivering solutions in technology and infrastructure, artificial\nintelligence and knowledge generation, and education and workforce development.\nIn the spirit of community, we intend for this work to foster discussion and\ndrive best practices as our field grows."
    },
    {
        "anchor": "Phase transitions in titanium with an analytic bond-order potential: Titanium is the base material for a number of technologically important\nalloys for energy conversion and structural applications. Atomic-scale studies\nof Ti-based metals employing first-principles methods, such as density\nfunctional theory, are limited to ensembles of a few hundred atoms. To perform\nlarge-scale and/or finite temperature simulations, computationally more\nefficient interatomic potentials are required. In this work, we coarse grain\nthe tight-binding (TB) approximation to the electronic structure and develop an\nanalytic bond-order potential (BOP) for Ti by fitting to the energies and\nforces of elementary deformations of simple structures. The BOP predicts the\nstructural properties of the stable and defective phases of Ti with a quality\ncomparable to previous TB parametrizations at a much lower computational cost.\nThe predictive power of the model is demonstrated for simulations of\nmartensitic transformations.",
        "positive": "Persistence of Island Arrangements During Layer-by-Layer Growth Revealed\n  Using Coherent X-rays: Understanding surface dynamics during epitaxial film growth is key to growing\nhigh quality materials with controllable properties. X-ray photon correlation\nspectroscopy (XPCS) using coherent x-rays opens new opportunities for in situ\nobservation of atomic-scale fluctuation dynamics during crystal growth. Here,\nwe present the first XPCS measurements of 2D island dynamics during\nhomoepitaxial growth in the layer-by-layer mode. Analysis of the results using\ntwo-time correlations reveals a new phenomenon - a memory effect in island\nnucleation sites on successive crystal layers. Simulations indicate that this\npersistence in the island arrangements arises from communication between\nislands on different layers via adatoms. With the worldwide advent of new\ncoherent x-ray sources, the XPCS methods pioneered here will be widely\napplicable to atomic-scale processes on surfaces."
    },
    {
        "anchor": "Copper Replaces Tin: A Copper based Gelling Catalyst for Poly-Urethane\n  from Discarded Motherboard: A discarded motherboard based eco-friendly copper catalyst has been\nprogrammed to replace the industrially used tin based catalyst DBTDL. The\ncatalyst has been characterized by UV-Vis spectroscopy, FT-IR and TEM. Using\nthe catalyst reaction conditions is optimized and under the optimized\ncondition, both polyurethane and polyurethane foam are prepared, thus proving\nthe generality of the catalyst to be used in industries. A possible mechanism\nhas also been proposed.",
        "positive": "High Pressure Suppression of Plasticity due to Over-Nucleation of Shear\n  Strain: High pressure shear band formation is a critical phenomenon in energetic\nmaterials due to its influence on both mechanical strength and mechanochemical\nactivation. While shear banding is know to occur in a variety of these\nmaterials, the governing dynamics of the mechanisms is not well defined for\nmolecular crystals. We conduct molecular dynamics simulations of shock wave\ninduced shear band formation in the energetic material\n1,3,5-trinitroperhydro-1,3,5-triazine (RDX) to assess shear band nucleation\nprocesses. We find, that at high pressures, the initial formation sites for\nshear bands 'over-nucleate' and rapidly lower deviatoric stresses prior to\nshear band formation and growth. This results in the suppression of plastic\ndeformation. A local cluster analysis is used to quantify and contrast this\nmechanism with a more typical shear banding seen at lower pressures. These\nresults demonstrate a mechanism that is reversible in nature and that\nsupersedes shear band formation at increased pressures. We anticipate that\nthese results will have a broad impact on the modeling and development of high\nstrain rate application materials such as those for high explosives and\nhypersonic systems."
    },
    {
        "anchor": "Comprehensive modeling of Joule heated cantilever probes: The thermo-electrical properties of a complex silicon cantilever structure\nused in thermal scanning probe lithography are modeled based on well\nestablished empirical laws for the thermal conductivity in silicon, the\nelectrical conductivity in the degenerate silicon support structure, and a\ncomprehensive physical model of the electrical conductivity in the low-doped\nheater structure. The model calculations are performed using a set of\nphysically well defined material parameters and finite element methods to solve\nthe coupled thermal and electrical diffusion equations in the cantilever. The\nmaterial parameters are determined from a non-linear regression fit of the\nnumerical results to corresponding measured data which also includes Raman\nmeasurements of the heater temperature. Excellent agreement between predicted\nand measured data in the absence of air cooling is obtained if a tapered doping\nprofile in the heater is used. The heat loss through the surrounding air is\nalso studied in a parameter free three-dimensional simulation. The simulation\nreveals that the heater temperature can be accurately predicted from the\nelectrical power supplied to the cantilever via a global scaling of the power\nin the power-temperature correlation function which can be determined from the\nvacuum simulation.",
        "positive": "Ab initio GW many-body effects in graphene: We present an {\\it ab initio} many-body GW calculation of the self-energy,\nthe quasiparticle band plot and the spectral functions in free-standing undoped\ngraphene. With respect to other approaches, we numerically take into account\nthe full ionic and electronic structure of real graphene and we introduce\nelectron-electron interaction and correlation effects from first principles.\nBoth non-hermitian and also dynamical components of the self-energy are fully\ntaken into account. With respect to DFT-LDA, the Fermi velocity is\nsubstantially renormalized and raised by a 17%, in better agreement with\nmagnetotransport experiments. Furthermore, close to the Dirac point the linear\ndispersion is modified by the presence of a kink, as observed in ARPES\nexperiments. Our calculations show that the kink is due to low-energy $\\pi \\to\n\\pi^*$ single-particle excitations and to the $\\pi$ plasmon. Finally, the GW\nself-energy does not open the band gap."
    },
    {
        "anchor": "Relation of open circuit voltage to charge carrier density in organic\n  bulk heterojunction solar cells: The open circuit voltage Voc and the corresponding charge carrier density\nwere measured in dependence of temperature and illumination intensity by\ncurrent-voltage and charge extraction measurements for P3HT:PCBM and\nP3HT:bisPCBM solar cells. At lower temperatures a saturation of Voc was\nobserved which can be explained by energetic barriers at the contacts\n(metal-insulator-metal model). Such injection barriers can also influence Voc\nat room temperature and limit the performance of the working solar cell, as was\nassured by macroscopic device simulations on temperature-dependent IV\ncharacteristics. However, under most conditions - room temperature and low\nbarriers - Voc is given by the effective bandgap.",
        "positive": "Optimization of the growth of the van der Waals materials Bi2Se3 and\n  (Bi0.5In0.5)2Se3 by molecular beam epitaxy: The naturally existing chalcogenide Bi2Se3 is topologically nontrivial due to\nthe band inversion caused by strong spin-orbit coupling inside the bulk of the\nmaterial. The surface states are spin polarized, protected by the\ntime-inversion symmetry, and thus robust to the scattering caused by\nnon-magnetic defects. A high purity topological insulator thin film can be\neasily grown via molecular beam epitaxy (MBE) on various substrates to enable\nnovel electronics, optics, and spintronics applications. However, the unique\nsurface state properties have historically been limited by the film quality,\nwhich is evaluated by crystallinity, surface morphology, and transport data.\nHere we propose and investigate different MBE growth strategies to improve the\nquality of Bi2Se3 thin films grown by MBE. In addition, growths of topological\ntrivial insulator (Bi0.5In0.5)2Se3 (BIS) are also investigated. BIS is often\nused as a buffer layer or separation layer for topological insulator\nheterostructures. Based on the surface passivation status, we have classified\nthe substrates into two categories, self-passivated or unpassivated, and\ndetermine the optimal growth mechanisms on the representative sapphire and\nGaAs, respectively. Growth temperature is a crucial control parameter for the\nvan der Waals epitaxy for both types of substrates. For Bi2Se3 on GaAs, the\nsurface passivation status determines the dominant growth mechanism."
    },
    {
        "anchor": "Magnetic ordering above room temperature in the sigma-phase of Fe66V34: Magnetic properties of four sigma-phase Fe_(100-x)V_x samples with\n34.4<x<55.1 were investigated by Mossbauer spectroscopy and magnetic\nmeasurements in the temperature interval 5-300 K. Four magnetic quantities viz.\nhyperfine field, Curie temperature, magnetic moment and susceptibility were\ndetermined. The sample containing 34.4 at% V was revealed to exhibit the\nlargest values found up to now for the sigma-phase for average hyperfine field,\nB = 12.1 T, average magnetic moment per Fe atom, m = 0.89 mB, and Curie\ntemperature, TC = 315.5 K. The quantities were shown to be strongly correlated\nwith each other. In particular, TC is linearly correlated with m with a slope\nof 406.5 K/mB, as well as B is so correlated with m yielding 14.3 T/mB for the\nhyperfine coupling constant.",
        "positive": "Significant Dzyaloshinskii-Moriya Interaction at Graphene-Ferromagnet\n  Interfaces due to Rashba-effect: The possibility of utilizing the rich spin-dependent properties of graphene\nhas attracted great attention in pursuit of spintronics advances. The promise\nof high-speed and low-energy consumption devices motivates a search for layered\nstructures that stabilize chiral spin textures such as topologically protected\nskyrmions. Here we demonstrate that chiral spin textures are induced at\ngraphene/ferromagnetic metal interfaces. This is unexpected because graphene is\na weak spin-orbit coupling material and is generally not expected to induce\nsufficient Dzyaloshinskii-Moriya interaction to affect magnetic chirality. We\ndemonstrate that graphene induces a new type of Dzyaloshinskii-Moriya\ninteraction due to a Rashba effect. First-principles calculations and\nexperiments using spin-polarized electron microscopy show that this\ngraphene-induced Dzyaloshinskii-Moriya interaction can have similar magnitude\nas at interfaces with heavy metals. This work paves a new path towards\ntwo-dimensional material based spin orbitronics."
    },
    {
        "anchor": "First principles study of the electronic and magnetic structures of the\n  tetragonal and orthorhombic phases of Ca3Mn2O7: On the basis of density functional theory electronic band structure\ncalculations using the augmented spherical wave method, the electronic and\nmagnetic properties of the orthorhombic and tetragonal phases of Ca3Mn2O7 were\ninvestigated and the spin exchange interactions of the orthorhombic phase were\nanalyzed. Our calculations show that the magnetic insulating states are more\nstable than the non-magnetic metallic state for both polymorphs of Ca3Mn2O7,\nthe orthorhombic phase is more stable than the tetragonal phase, and the ground\nstate of the orthorhombic phase is antiferromagnetic. The total energies\ncalculated for the three spin states of the orthorhombic phase of Ca3Mn2O7 led\nto estimates of the spin exchange interactions Jnn = -3.36 meV and Jnnn = -0.06\nmeV. The accuracy of these estimates were tested by calculating the Curie-Weiss\ntemperature within the mean-field approximation.",
        "positive": "Impact of boron atom clustering on the electronic structure of (B,In)N\n  alloys: Tailoring the electronic and optical properties of nitride-based alloys for\noptoelectronic applications in the ultraviolet and red spectral range has\nattracted significant attention in recent years. Adding boron nitride (BN) to\nindium gallium nitride, (In,Ga)N, alloys, can help to control the lattice\nmismatch between (In,Ga)N and GaN and may thus allow reduction of strain\nrelated defect formation. However, understanding of the impact of BN on the\nelectronic properties of III-N alloys, in particular the influence of\nexperimentally observed boron atom clustering, is sparse. This work presents\nfirst-principles calculations investigating the electronic properties of\n(B,In)N alloys with boron contents between 2% and 7%. Special attention is paid\nto the impact of the alloy microstructure. While the results show that the\nlattice constants of such alloys largely agree with lattice constants\ndetermined from a Vegard approximation, the electronic properties strongly\ndepend on the local boron atom configurations. For instance, if boron atoms are\ndispersed throughout the structure and are not sharing nitrogen atoms, the band\ngap of (B,In)N alloys is largely unaffected and stays close to the gap of\npristine InN. However, in the case of boron atom clustering, e.g., when boron\natoms are sharing nitrogen atoms, the band gap can be strongly reduced, often\nleading to a metallic state in (B,In)N alloys. These strong band gap reductions\nare mainly driven by carrier localization effects in the valence band. The\ncalculations thus show that the electronic structure of (B,In)N alloys strongly\ndepends on the alloy microstructure and that boron atom clustering plays an\nimportant role in understanding the electronic and optical properties of these\nemerging materials."
    },
    {
        "anchor": "Universal recovery of the bright-exciton level-degeneracy in quantum\n  dots without structural symmetry: The lack of structural symmetry which usually characterizes semiconductor\nquantum dots lifts the energetic degeneracy of the bright excitonic states and\nhampers severely their use as high fidelity sources of entangled photons. We\ndemonstrate experimentally and theoretically that it is always possible to\nrestore the excitonic degeneracy by the simultaneous application of large\nstrain and electric fields, despite the fact that this possibility has\nfundamentally been doubted. This is achieved by using one external perturbation\nto align the polarization of the exciton emission along the axis of the second\nperturbation, which then erases completely the energy splitting of the states.\nThis result, which holds for any QD structure, highlights the potential of\ncombining complementary external fields to create artificial atoms meeting the\nstringent requirements posed by scalable semiconductor-based\nquantum-technology.",
        "positive": "Stress Induced Structural Transformations in Au Nanocrystals: Nanocrystals can exist in multiply twinned structures like the icosahedron,\nor single crystalline structures like the cuboctahedron or Wulff-polyhedron.\nStructural transformation between these polymorphic structures can proceed\nthrough diffusion or displacive motion. Experimental studies on nanocrystal\nstructural transformations have focused on high temperature diffusion mediated\nprocesses. Thus, there is limited experimental evidence of displacive motion\nmediated structural transformations. Here, we report the high-pressure\nstructural transformation of 6 nm Au nanocrystals under nonhydrostatic pressure\nin a diamond anvil cell that is driven by displacive motion. In-situ X-ray\ndiffraction and transmission electron microscopy were used to detect the\ntransformation of multiply twinned nanocrystals into single crystalline\nnanocrystals. High-pressure single crystalline nanocrystals were recovered\nafter unloading, however, the nanocrystals quickly reverted back to multiply\ntwinned state after redispersion in toluene solvent. The dynamics of recovery\nwas captured using transmission electron microscopy which showed that the\nrecovery was governed by surface recrystallization and rapid twin boundary\nmotion. We show that this transformation is energetically favorable by\ncalculating the pressure-induced change in strain energy. Molecular dynamics\nsimulations showed that defects nucleated from a region of high stress region\nin the interior of the nanocrystal, which make twin boundaries unstable.\nDeviatoric stress driven Mackay transformation and dislocation/disclination\nmediated detwinning are hypothesized as possible mechanisms of high-pressure\nstructural transformation."
    },
    {
        "anchor": "Thermoelectric properties of Fe$_{2}$VAl at high temperature region: A\n  combined experimental and theoretical study: Heusler type compounds have long been recognized as potential thermoelectric\n(TE) materials. Here, the experimentally observed TE properties of Fe$_{2}$VAl\nare understood through electronic structure calculations in the temperature\nrange of $300-800$ K. The observed value of $S$ is $\\sim-$138 $\\mu$V/K at 300\nK. Then, the $|S|$ decreases with increase in temperature up to the highest\ntemperature with the value of $\\sim-$18 $\\mu$V/K at 800 K. The negative sign of\n$S$ in the full temperature window signifies the dominating $n$-type character\nof the compound. The temperature dependent of electrical conductivity, $\\sigma$\n(thermal conductivity, $\\kappa$) exhibits the increasing (decreasing) trend\nwith the values of $\\sim$1.2 $\\times$ 10$^{5}$ $\\Omega^{-1}$m$^{-1}$\n($\\sim$23.7 W/m-K) and $\\sim$2.2 $\\times$ 10$^{5}$ $\\Omega^{-1}$m$^{-1}$\n($\\sim$15.3 W/m-K) at 300 K and 800 K, respectively. In order to understand\nthese transport properties, the DFT based semi-classical Boltzmann theory is\nused. The contributions of multi-band electron and hole pockets are found to be\nmainly responsible for the temperature dependent trend of these properties. The\ndecrement of $|S|$ and increment of $\\sigma/\\tau$ $\\&$ $\\kappa_{e}/\\tau$\n($\\tau$ is relaxation time) with temperature is directly related with the\ncontribution of multiple hole pockets. Present study suggests that DFT based\nelectronic calculations provide reasonably good explanations of experimental TE\nproperties of Fe$_{2}$VAl in the high temperature range of $300-800$ K.",
        "positive": "Sub-micrometer phonon mean free paths in metal-organic frameworks\n  revealed by machine-learning molecular dynamics simulations: Metal-organic frameworks (MOFs) are a family of materials that have high\nporosity and structural tunability and hold great potential in various\napplications, many of which requiring a proper understanding of the thermal\ntransport properties. Molecular dynamics (MD) simulations play an important\nrole in characterizing the thermal transport properties of various materials.\nHowever, due to the complexity of the structures, it is difficult to construct\naccurate empirical interatomic potentials for reliable MD simulations of MOFs.\nTo this end, we develop a set of accurate yet highly efficient machine-learned\npotentials for three typical MOFs, including MOF-5, HKUST-1, and ZIF-8, using\nthe neuroevolution potential approach as implemented in the GPUMD package, and\nperform extensive MD simulations to study thermal transport in the three MOFs.\nAlthough the lattice thermal conductivity (LTC) values of the three MOFs are\nall predicted to be smaller than 1 $\\rm{W/(m\\ K)}$ at room temperature, the\nphonon mean free paths (MFPs) are found to reach the sub-micrometer scale in\nthe low-frequency region. As a consequence, the apparent LTC only converges to\nthe diffusive limit for micrometer single crystals, which means that the LTC is\nheavily reduced in nanocrystalline MOFs. The sub-micrometer phonon MFPs are\nalso found to be correlated with a moderate temperature dependence of LTC\nbetween those in typical crystalline and amorphous materials. Both the large\nphonon MFPs and the moderate temperature dependence of LTC fundamentally change\nour understanding of thermal transport in MOFs."
    },
    {
        "anchor": "Automatic Identification of Crystal Structures and Interfaces via\n  Artificial-Intelligence-based Electron Microscopy: Characterizing crystal structures and interfaces down to the atomic level is\nan important step for designing advanced materials. Modern electron microscopy\nroutinely achieves atomic resolution and is capable to resolve complex\narrangements of atoms with picometer precision. Here, we present AI-STEM, an\nautomatic, artificial-intelligence based method, for accurately identifying key\ncharacteristics from atomic-resolution scanning transmission electron\nmicroscopy (STEM) images of polycrystalline materials. The method is based on a\nBayesian convolutional neural network (BNN) that is trained only on simulated\nimages. AI-STEM automatically and accurately identifies crystal structure,\nlattice orientation, and location of interface regions in synthetic and\nexperimental images. The model is trained on cubic and hexagonal crystal\nstructures, yielding classifications and uncertainty estimates, while no\nexplicit information on structural patterns at the interfaces is included\nduring training. This work combines principles from probabilistic modeling,\ndeep learning, and information theory, enabling automatic analysis of\nexperimental, atomic-resolution images.",
        "positive": "Molecular Dynamics Simulations of Tensile Behavior of Copper: Molecular dynamics simulations on tensile deformation of initially defect\nfree single crystal copper nanowire oriented in <001>{100} has been carried out\nat 10 K under adiabatic and isothermal loading conditions. The tensile\nbehaviour was characterized by sharp rise in stress in elastic regime followed\nby sudden drop at the point of dislocation nucleation. The important finding is\nthat the variation in dislocation density is correlated with the observed\nstress-strain response. Several interesting micro- structural features were\nobserved during tensile deformation such as slip, phase transformation and\npentagonal structure in necking region affecting the plastic deformation\nbehaviour of single crystal copper nanowire."
    },
    {
        "anchor": "Electrochemical lithium intercalation in nanosized manganese oxides: X-ray amorphous manganese oxides were prepared by reduction of sodium\npermanganate by lithium iodide in aqueous medium (MnOx-I) and by decomposition\nof manganese carbonate at moderate temperature (MnOx-C). TEM showed that these\nmaterials are not amorphous, but nanostructured, with a prominent spinel\nsubstructure in MnOx-C. These materials intercalate lithium with capacities up\nto 200 mAh/g at first cycle (potential window 1.8-4.3 V) and 175 mAh/g at 100th\ncycle. Best performances for MnOx-C are obtained with cobalt doping. Potential\nelectrochemical spectroscopy shows that the initial discharge induces a 2-phase\ntransformation in MnOx-C phases, but not in MnOx-I ones. EXAFS and XANES\nconfirm the participation of manganese in the redox process, with variations in\nlocal structure much smaller than in known long-range crystallized manganese\noxides. X-ray absorption spectroscopy also shows that cobalt in MnOx-C is\ndivalent and does not participate in the electrochemical reaction.",
        "positive": "Structural Domain Walls in Polar Hexagonal Manganites: We present a microscopic first-principles study of the neutral structural\ndomain walls (DWs) in the multiferroic hexagonal manganites, which have been\nshown to exhibit cross-couplings between ferroelectricity and struc- tural\nantiphase. We find that, in contradiction with previously proposed models, the\ninterlocked antiphase- ferroelectric domain walls have approximately zero\nwidth, and their energy is lower than that of antiphase-only or\nferroelectric-only domain walls. Furthermore, we show that the\nferroelectric-only and antiphase-only DWs are superpositions of interlocked\nantiphase ferroelectric (AP+FE) DWs and intermediate domains inevitably exist\nthrough the DWs. Our results shed light on the question of why only AP+FE DWs\nare observed and how the topological defects emerge in polar hexagonal\nmanganites."
    },
    {
        "anchor": "DISO: A Domain Ontology for Modeling Dislocations in Crystalline\n  Materials: Crystalline materials, such as metals and semiconductors, nearly always\ncontain a special defect type called dislocation. This defect decisively\ndetermines many important material properties, e.g., strength, fracture\ntoughness, or ductility. Over the past years, significant effort has been put\ninto understanding dislocation behavior across different length scales via\nexperimental characterization techniques and simulations. This paper introduces\nthe dislocation ontology (DISO), which defines the concepts and relationships\nrelated to linear defects in crystalline materials. We developed DISO using a\ntop-down approach in which we start defining the most general concepts in the\ndislocation domain and subsequent specialization of them. DISO is published\nthrough a persistent URL following W3C best practices for publishing Linked\nData. Two potential use cases for DISO are presented to illustrate its\nusefulness in the dislocation dynamics domain. The evaluation of the ontology\nis performed in two directions, evaluating the success of the ontology in\nmodeling a real-world domain and the richness of the ontology.",
        "positive": "Cathodic Carbon Chemically Adsorbs Carbon Dioxide: Why Is it True?: Large-scale applications are waiting for an optimal CO2 scavenger to\nreinforce CCS and CCU technologies. We herein introduce and succinctly validate\na new philosophy of capturing gaseous CO2 by negatively-charged carbonaceous\nstructures. The chemical absorption of CO2 turns out possible thanks to the\nemergence of significant nucleophilic interaction carbon centers upon applying\nvoltage. The carbonaceous cathode, therefore, may serve as a prototype of a new\nCO2 sorbent. As a model to simulate chemisorption, we used a small-sized\ngraphene quantum dot (GQD). According to the recorded reaction profiles, the\nnegatively charged GQD containing 16 carbon atoms readily reacts with the CO2\nmolecule and produces carboxylated GQD. In turn, the activation energy (60\nkJ/mol) and energy effect (-55 kJ/mol) for the reaction in water appeared\nsurprisingly competitive in the context of the literature. We hypothesize that\nthe carbonaceous cathode deserves in-depth experimental research as a possible\nCO2 chemical sorbent. Despite we used GQD for simulations, the encouraging\nresults can be extrapolated to other nanoscale carbons and, more importantly,\nto the activated carbon species widely employed in modern electrochemical\ndevices."
    },
    {
        "anchor": "Polycrystalline MnBi as a transverse thermoelectric material: To assess the potential of polycrystalline MnBi as a transverse\nthermoelectric material, we have experimentally investigated its anomalous\nNernst effect (ANE) by means of the heat flux method. We prepared MnBi samples\nby powder metallurgy; this technique allows the preparation of samples in\narbitrary shapes with the possibility to tailor their magnetic properties. In\nthe material exhibiting the highest remanent magnetization, we found a value of\nthe ANE thermopower of -1.1 $\\mu$V/K at 1 T, after the compensation of the\nordinary Nernst effect from pure bismuth present inside the polycrystalline\nsample. This value is comparable with those reported in the literature for\nsingle crystals.",
        "positive": "Exploring physics of ferroelectric domain walls via Bayesian analysis of\n  atomically resolved STEM data: The physics of ferroelectric domain walls is explored using the Bayesian\ninference analysis of atomically resolved STEM data. We demonstrate that domain\nwall profile shapes are ultimately sensitive to the nature of the order\nparameter in the material, including the functional form of\nGinzburg-Landau-Devonshire expansion, and numerical value of the corresponding\nparameters. The preexisting materials knowledge naturally folds in the Bayesian\nframework in the form of prior distributions, with the different order\nparameters forming competing (or hierarchical) models. Here, we explore the\nphysics of the ferroelectric domain walls in BiFeO3 using this method, and\nderive the posterior estimates of relevant parameters. More generally, this\ninference approach both allows learning materials physics from experimental\ndata with associated uncertainty quantification, and establishing guidelines\nfor instrumental development answering questions on what resolution and\ninformation limits are necessary for reliable observation of specific physical\nmechanisms of interest."
    },
    {
        "anchor": "General Scattering Mechanism and Transport in Graphene: Using quasi-time dependent semi-classical transport theory in RTA, we\nobtained coupled current equations in the presence of time varying field and\nbased on general scattering mechanism $\\tau \\propto \\mathcal{E}^{\\beta}$. We\nfind that close to the Dirac point, the characteristic exponent $\\beta = +2$\ncorresponds to acoustic phonon scattering. $\\beta = +1$ long-range Coulomb\nscattering mechanism. $\\beta = -1$ is short-range delta potential scattering in\nwhich the conductivity is constant of temperature. The $\\beta = 0$ case is\nballistic limit. In the low energy dynamics of Dirac electrons in graphene, the\neffect of the time-dependent electric field is to alter just the electron\ncharge by $e \\to e(1 + (\\Omega \\tau)^2)$ making electronic conductivity\nnon-linear. The effect of magnetic filed is also considered.",
        "positive": "General corner charge formulas in various tetrahedral and cubic space\n  groups: In some insulators, corner charges are fractionally quantized, due to the\ntopological invariant called a filling anomaly. The previous theories of\nfractional corner charges have been mostly limited to two-dimensional systems.\nIn three dimensions, only limited cases have been studied. In this study, we\nderive formulas for the filling anomaly and the corner charge in various\ncrystals with all the tetrahedral and cubic space groups. We discuss that the\nquantized corner charge requires the crystal shapes to be vertex-transitive\npolyhedra. We show that the formula of the filling anomaly is universally given\nby the difference between electronic and ionic charges at the Wyckoff position\n1a. The fractional corner charges appear by equally distributing the filling\nanomaly to all the corners of the crystal. We also derive the k-space formulas\nfor the fractional corner charge. In some cases, the corner charge is not\ndetermined solely from the irreps at high-symmetry k-points. In such cases, we\nintroduce a new Z2 topological invariant to determine the corner charge."
    },
    {
        "anchor": "Precise Damage Shaping in Self-Sensing Composites Using Electrical\n  Impedance Tomography and Genetic Algorithms: Fiber-reinforced composites with nanofiller-modified polymer matrices have\nimmense potential to improve the safety of high-risk engineering structures.\nThese materials are intrinsically self-sensing because their electrical\nconductivity is affected by deformations and damage. This property, known as\npiezoresistivity, has been extensively leveraged for conductivity-based damage\ndetection via electrical resistance change methods and tomographic imaging\ntechniques such as electrical impedance tomography (EIT). Although these\ntechniques are very effective at detecting the presence of damage, they suffer\nfrom an inability to provide precise information about damage shape, size, or\nmechanism. This is particularly detrimental for laminated composites which can\nsuffer from complex failure modes, such as delaminations, that are difficult to\ndetect. To that end, we herein propose a new technique for precisely\ndetermining damage shape and size in self-sensing composites. Our technique\nmakes use of a genetic algorithm (GA) integrated with realistic physics-based\ndamage models to recover precise damage shape from conductivity changes imaged\nvia EIT. We experimentally validate this technique on carbon nanofiber\n(CNF)-modified glass fiber-reinforced polymer (GFRP) laminates by considering\ntwo specific damage mechanisms: through-holes and delaminations. Our results\nshow that this novel technique can accurately reconstruct multiple\nthrough-holes with radii as small as 1.19 mm and delaminations caused by low\nvelocity impacts. These findings illustrate that coupling piezoresistivity with\nconductivity-based spatial imaging techniques and physics-based inversion\nstrategies can enable damage shaping capabilities in self-sensing composite\nstructures.",
        "positive": "Evidence of Topological Surface State in Three-Dimensional Dirac\n  Semimetal Cd3As2: The three-dimensional topological semimetals represent a new quantum state of\nmatter. Distinct from the surface state in the topological insulators that\nexhibits linear dispersion in two-dimensional momentum plane, the\nthree-dimensional semimetals host bulk band dispersions linearly along all\ndirections, forming discrete Dirac cones in three-dimensional momentum space.\nIn addition to the gapless points (Weyl/Dirac nodes) in the bulk, the\nthree-dimensional Weyl/Dirac semimetals are also characterized by\n\"topologically protected\" surface state with Fermi arcs on their specific\nsurface. The Weyl/Dirac semimetals have attracted much attention recently they\nprovide a venue not only to explore unique quantum phenomena but also to show\npotential applications. While Cd3As2 is proposed to be a viable candidate of a\nDirac semimetal, more experimental evidence and theoretical investigation are\nnecessary to pin down its nature. In particular, the topological surface state,\nthe hallmark of the three-dimensional semimetal, has not been observed in\nCd3As2. Here we report the electronic structure of Cd3As2 investigated by\nangle-resolved photoemission measurements on the (112) crystal surface and\ndetailed band structure calculations. The measured Fermi surface and band\nstructure show a good agreement with the band structure calculations with two\nbulk Dirac-like bands approaching the Fermi level and forming Dirac points near\nthe Brillouin zone center. Moreover, the topological surface state with a\nlinear dispersion approaching the Fermi level is identified for the first time.\nThese results provide strong experimental evidence on the nature of\ntopologically non-trivial three-dimensional Dirac cones in Cd3As2."
    },
    {
        "anchor": "Breakdown of Conventional Winding Number Calculation in One-Dimensional\n  Lattices with Interactions Beyond Nearest Neighbors: Topological insulators hold promises to realize exotic quantum phenomena in\nelectronic, photonic, and phononic systems. Conventionally, topological\nindices, such as winding numbers, have been used to predict the number of\ntopologically protected domain-wall states (TPDWSs) in topological insulators,\na signature of the topological phenomenon called bulk-edge correspondence.\nHere, we demonstrate theoretically and experimentally that the number of TPDWSs\nin a mechanical Su-Schrieffer-Heeger (SSH) model can be higher than the winding\nnumber depending on the strengths of beyond-nearest-neighbor interactions,\nrevealing the breakdown of the winding number prediction. Alternatively, we\nresort to the Berry connection to accurately characterize the number and\nspatial features of TPDWSs in SSH systems, further confirmed by the\nJackiw-Rebbi theory proving that the multiple TPDWSs correspond to the bulk\nDirac cones. Our findings deepen the understanding of complex network dynamics\nand offer a generalized paradigm for precise TPDWS prediction in potential\napplications involving localized vibrations, such as drug delivery and quantum\ncomputing.",
        "positive": "Orientational Contribution to the Giant Electrostriction Effect and\n  Dielectric Permittivity in Relaxors: A microscopic model is developed considering randomly oriented polar regions\nstuck to the directions of random fields or stresses. The application of an\nexternal field (stress) in this model results in a dielectric and acoustic\nreply connected with a polarization (strain) rotation. Polarization (strain)\nfluctuation contributions are also studied."
    },
    {
        "anchor": "Landau Level Spectroscopy of Dirac Electrons in a Polar Semiconductor\n  with Giant Rashba Spin Splitting: Optical excitations of BiTeI with large Rashba spin splitting have been\nstudied in an external magnetic field ($B$) applied parallel to the polar axis.\nA sequence of transitions between the Landau levels (LLs), whose energies are\nin proportion to $\\sqrt{B}$ were observed, being characteristic of massless\nDirac electrons. The large separation energy between the LLs makes it possible\nto detect the strongest cyclotron resonance even at room temperature in\nmoderate fields. Unlike in 2D Dirac systems, the magnetic field induced\nrearrangement of the conductivity spectrum is directly observed.",
        "positive": "Observation of chiral solitons in the quantum spin liquid phase of\n  LiCuVO$_4$: Quantum spin liquids represent a magnetic ground state arising in the\npresence of strong quantum fluctuations that preclude ordering down to zero\ntemperature and leave clear fingerprints in the excitation spectra. While\ntheory bears a variety of possible quantum spin liquid phases their\nexperimental realization is still scarce. Here, we report the first\nexperimental evidence of a vector-chiral quantum spin liquid state in the\n$S=1/2$ spin chain compound LiCuVO$_4$ from measurements of the complex\npermittivity $\\varepsilon^*$ in the GHz range. In zero magnetic field our\nresults show short-lived thermally activated chiral fluctuations above the\nmultiferroic phase transition at $T_\\mathrm{N}=2.4$ K with divergent life-times\nwhen approaching $T_\\mathrm{N}$. In $\\varepsilon^*$ this fluctuation dynamics\nare seen as the slowing down of a relaxation with a critical dynamical exponent\n$\\nu_\\xi z \\approx 1.3$ in agreement with mean-field predictions. When using a\nmagnetic field to suppress $T_N$ towards 0 K the influence of quantum\nfluctuations is increased until they condense into the chrial spin liquid phase\nbelow 400 mK. Within this phase we measure a nearly-gapless chiral soliton\nexcitation with a tiny energy gap of $E_\\mathrm{SE}\\approx14.1$ $\\mu$eV."
    },
    {
        "anchor": "Ultrasoft pseudopotentials with kinetic energy density support:\n  implementing the modified Becke-Johnson potential: We extend the Vanderbilt ultrasoft pseudopotential scheme by adding kinetic\nenergy density terms, in order to use meta-GGA exchange potentials, such as the\nBecke-Johnson or Tran-Blaha potentials, in the planewave-pseudopotential\nimplementation of Density Functional Theory. Having implemented kinetic energy\naugmentation and non-linear core correction terms in the CASTEP density\nfunctional package, we evaluate the validity of our approach by comparing the\ncalculated electronic structure of isolated atoms and semiconductor crystals to\nall-electron benchmark calculations. Based on our results, we provide\nrecommendations for the practical use of the Tran-Blaha exchange in\nplanewave-pseudopotential codes.",
        "positive": "Experimental discovery of bulk-disclination correspondence: Most natural and artificial materials have crystalline structures from which\nabundant topological phases emerge [1-6]. The bulk-edge correspondence,\nwidely-adopted in experiments to determine the band topology from edge\nproperties, however, becomes inadequate in discerning various topological\ncrystalline phases [7-17], leading to great challenges in the experimental\nclassification of the large family of topological crystalline materials [4-6].\nTheories predict that disclinations, ubiquitous crystallographic defects,\nprovide an effective probe of crystalline topology beyond edges [18-21], which,\nhowever, has not yet been confirmed in experiments. Here, we report the\nexperimental discovery of the bulk-disclination correspondence which is\nmanifested as the fractional spectral charge and robust bound states at the\ndisclinations. The fractional disclination charge originates from the\nsymmetry-protected bulk charge patterns---a fundamental property of many\ntopological crystalline insulators (TCIs). Meanwhile, the robust bound states\nat disclinations emerge as a secondary, but directly observable property of\nTCIs. Using reconfigurable photonic crystals as photonic TCIs with higher-order\ntopology, we observe those hallmark features via pump-probe and near-field\ndetection measurements. Both the fractional charge and the localized states are\ndemonstrated to emerge at the disclination in the TCI phase but vanish in the\ntrivial phase. The experimental discovery of bulk-disclination correspondence\nunveils a novel fundamental phenomenon and a new paradigm for exploring\ntopological materials."
    },
    {
        "anchor": "Nature of magnetism and transport in BxCyNz thin films: The intriguing\n  role of nitrogen defects in the electronic structure: Boron carbonitride (BxCyNz) represents an interesting family of materials\ncontaining all light elements and two dimensional graphene like hybrid layers.\nAlthough rich literature exists on this peculiar material in chemically\nprocessed form, there are relatively fewer reports on device application-worthy\nthin film form. This form also offers a natural platform for basic studies on\nimportant aspects such as magnetism and transport, which have attracted\nattention in the context of ferromagnetism in doped and defect carbon systems.\nThus, in this work we have grown thin films of this compound using Pulsed Laser\nDeposition (PLD) method, and investigated their magnetic and transport\nproperties in their entirety along with the detailed electronic structure using\nvarious spectroscopic techniques like X-ray photoelectron spectroscopy (XPS),\nValence Band Spectroscopy (VBS) and X-ray absorption near edge spectroscopy\n(XANES). In depth analysis of the typical role of dopants and defects,\nespecially the prevalent nitrogen defects, is elucidated using Density\nFunctional Theory (DFT) calculations to understand the experimental\nobservations. A dramatic crossover in the transport mechanism of charge\ncarriers is observed in this system with the change in doping level of specific\nnitrogen defects. A robust and high saturation magnetization is achieved in BCN\nfilms which is higher by almost hundred times as compared to that in similarly\ngrown undoped carbon film. An anomalous transition and increase in coercive\nfield is also observed at low temperature. A careful analysis brings out the\nintriguing role of specific nitrogen defects in defining the peculiar nature\nand concentration dependence of the physical properties of this system.",
        "positive": "Control of polymorphism during epitaxial growth of hyperferroelectric\n  candidate LiZnSb on GaSb (111)B: A major challenge for ferroelectric devices is the depolarization field,\nwhich competes with and often destroys long-range polar order in the limit of\nultrathin films. Recent theoretical predictions suggest a new class of\nmaterials, termed hyperferroelectics, that should be robust against the\ndepolarization field and enable ferroelectricity down to the monolayer limit.\nHere we demonstrate the epitaxial growth of hexagonal LiZnSb, one of the\nhyperferroelectric candidate materials, by molecular-beam epitaxy on GaSb\n(111)B substrates. Due to the high volatility of all three atomic species, we\nfind that LiZnSb can be grown in an adsorption-controlled window, using an\nexcess zinc flux. Within this window, the desired polar hexagonal phase is\nstabilized with respect to a competing cubic polymorph, as revealed by X-ray\ndiffraction and transmission electron microscopy measurements. First-principles\ncalculations show that for moderate amounts of epitaxial strain and moderate\nconcentrations of Li vacancies, the cubic LiZnSb phase is lower in formation\nenergy than the hexagonal phase, but only by a few meV per formula unit.\nTherefore we suggest that kinetics plays a role in stabilizing the desired\nhexagonal phase at low temperatures. Our results provide a path towards\nexperimentally demonstrating ferroelectricity and hyperferroelectricity in a\nnew class of ternary intermetallic compounds."
    },
    {
        "anchor": "Gas-to-nanotextile: high-performance materials from floating 1D\n  nanoparticles: Suspended in the gas phase, 1D inorganic nanoparticles (nanotubes and\nnanowires) grow to hundreds of microns in a second and can be thus directly\nassembled into freestanding network materials. The corresponding process\ncontinuously transforms gas precursors into aerosols into aerogels into\nmacroscopic nanotextiles. By enabling the assembly of very high aspect ratio\nnanoparticles, this processing route has translated into high-performance\nstructural materials, transparent conductors and battery anodes, amongst other\nembodiments. This paper reviews progress in the application of such\nmanufacturing process to nanotubes and nanowires. It analyses 1D nanoparticle\ngrowth through floating catalyst chemical vapour deposition (FCCVD), in terms\nof reaction selectivity, scalability and its inherently ultra-fast growth rates\n(107-108 atoms per second) up to 1000 times faster than for substrate CVD. We\nsummarise emerging descriptions of the formation of aerogels through\npercolation theory and multi-scale models for the collision and aggregation of\n1D nanoparticles. The paper shows that macroscopic ensembles of 1D\nnanoparticles resemble textiles in their porous network structure, high\nflexibility and damage-tolerance. Their bulk properties depend strongly on\ninter-particle properties and are dominated by alignment and volume fraction.\nSelected examples of nanotextiles that surpass granular and monolithic\nmaterials include structural fibres with polymer-like toughness, transparent\nconductors, and slurry-free composite electrodes for energy storage.",
        "positive": "Laser-induced torques in spin spirals: We investigate laser-induced torques in magnetically non-collinear\nferromagnets with a spin-spiral magnetic structure using \\textit{ab-initio}\ncalculations. Since spin-spirals may be used to approximate the magnetization\ngradients locally in domain walls and skyrmions, our method may be used to\nobtain the laser-induced torques in such objects from a multiscale approach.\nEmploying the generalized Bloch-theorem we obtain the electronic structure\ncomputationally efficiently. We employ our method to assess the laser-induced\ntorques in bcc Fe, hcp Co, and L$_{1}0$ FePt when a spin-spiral magnetic\nstructure is imposed. We find that the laser-induced torques in these\nmagnetically noncollinear systems may be orders of magnitude larger than those\nin the corresponding magnetically collinear systems and that they exist both\nfor linearly and circularly polarized light. This result suggests that\nlaser-induced torques driven by noncollinear magnetic order or by magnetic\nfluctuations may contribute significantly to processes in ultrafast magnetism."
    },
    {
        "anchor": "Investigation by STEM-EELS of helium density in nanobubbles formed in\n  aged palladium tritides: 3He nanobubbles created by radioactive decay of tritium in palladium tritide\nare investigated after several years of aging. Scanning Transmission Electron\nMicroscopy Electron Energy-Loss Spectroscopy (STEM-EELS) has been used to\nmeasure helium density from the helium K-edge around 23 eV. Helium densities\nwere found between 20 and 140 (+/-30) He/nm3 and the corresponding nanobubble\npressures range between 0.1 and 3 (+/-0.2) GPa. Measuring helium density and\nmapping He atoms by STEM-EELS enables to differentiate bubbles from empty\ncavities in the palladium tritide matrix.",
        "positive": "Unravelling spontaneous Bloch-type skyrmion in centrosymmetric\n  two-dimensional magnets: The realization of magnetic skyrmions in two-dimensional (2D) magnets holds\ngreat promise for both fundamental research and device applications. Despite\nrecent progress, two-dimensional skyrmion hosts are still limited, due to the\nfact that most 2D magnets are centrosymmetric and thus lack\nDzyaloshinskii-Moriya interaction (DMI). We show here, using a general analysis\nbased on symmetry, that Bloch-type skyrmions can, in fact, be stabilized in 2D\nmagnets, due to the interplay between in-plane component (dx) of second\nnearest-neighbor DMI and magnetic anisotropy. Its validity is demonstrated in\nthe Cr2Ge2Te6 monolayer, which is also verified by recent experiments. Our work\ngives a clear direction for experimental studies of 2D magnetic materials to\nstabilize skyrmions and should greatly enrich the research on magnetic\nskyrmions in 2D lattices."
    },
    {
        "anchor": "X-ray standing wave and reflectometric characterization of multilayer\n  structures: Microstructural characterization of synthetic periodic multilayers by x-ray\nstanding waves have been presented. It has been shown that the analysis of\nmultilayers by combined x-ray reflectometry (XRR) and x-ray standing wave (XSW)\ntechniques can overcome the deficiencies of the individual techniques in\nmicrostructural analysis. While interface roughnesses are more accurately\ndetermined by the XRR technique, layer composition is more accurately\ndetermined by the XSW technique where an element is directly identified by its\ncharacteristic emission. These aspects have been explained with an example of a\n20 period Pt/C multilayer. The composition of the C-layers due to Pt\ndissolution in the C-layers, Pt$_{x}$C$_{1-x}$, has been determined by the XSW\ntechnique. In the XSW analysis when the whole amount of Pt present in the\nC-layers is assumed to be within the broadened interface, it l eads to larger\ninterface roughness values, inconsistent with those determined by the XRR\ntechnique. Constraining the interface roughness values to those determined by\nthe XRR technique, requires an additional amount of dissolved Pt in the\nC-layers to expl ain the Pt fluorescence yield excited by the standing wave\nfield. This analysis provides the average composition Pt$_{x}$C$_{1-x}$ of the\nC-layers .",
        "positive": "The Piezoresponse Force Microscopy of surface layers and thin films:\n  effective response and resolution function: Signal formation mechanism of Piezoresponse Force Microscopy of piezoelectric\nsurface layers and thin films on stiff and elastically matched substrates is\nanalyzed and thickness dependence of effective piezoelectric response, object\ntransfer function components and Rayleigh two-point resolution are derived.\nObtained exact series and simple Pade approximations can be applied for the\neffective piezoresponse analytical calculations in the case of films capped on\ndifferent substrates. The effective piezoresponse is thickness dependent for\npiezoelectric films on substrates with low dielectric permittivity (extrinsic\nsize effect), whereas the thickness dependence is essentially suppressed for\ngiant permittivity or metallic substrates. Thus implications of analysis for\nferroelectric data storage and device applications are discussed."
    },
    {
        "anchor": "Structural, Electronic, and Magnetic Properties of HiPIMS Grown Co-N\n  Thin Films: We studied the growth behavior, structural, electronic, and magnetic\nproperties of cobalt nitride (Co-N) thin films deposited using direct current\n(dc) and high power impulse magnetron sputtering (HiPIMS) processes. The N$_2$\npartial gas flow (\\pn) was varied in close intervals to achieve the optimum\nconditions for the growth of tetra cobalt nitride (\\tcn) phase. We found that\nCo-N films grown using HiPIMS process adopt (111) orientation as compared to\nthe growth taking place along the (100) direction in the dcMS process. It was\nobserved that HiPIMS grown Co-N~films were superior in terms of crystallite\nsize and uniform surface morphology. The local structure of films was\ninvestigated using x-ray absorption fine structure (XAFS) measurements. We\nfound that the high energy of adatoms in the HiPIMS technique assisted in the\ngreater stabilization of fcc-Co and novel \\tcn~phase relative to the dcMS\nprocess. Magnetic properties of Co-N thin films were studied using\nmagneto-optical Kerr effect, vibrating sample magnetometry and polarized\nneutron reflectivity. It was found that though the saturation magnetization\nremains almost similar in films grown by dcMS or HiPIMS processes, they differ\nin terms of their magnetic anisotropy. Such variation can be understood in\nterms of differences in the growth mechanisms in dcMS and HiPIMS processes\naffecting the local structure of resulting \\tcn~phase.",
        "positive": "A basic electro-topological descriptor for the prediction of organic\n  molecule geometries by simple machine learning: This paper proposes a machine learning (ML) method to predict stable\nmolecular geometries from their chemical composition. The method is useful for\ngenerating molecular conformations which may serve as initial geometries for\nsaving time during expensive structure optimizations by quantum mechanical\ncalculations of large molecules. Conformations are found by predicting the\nlocal arrangement around each atom in the molecule after trained from a\ndatabase of previously optimized small molecules. It works by dividing each\nmolecule in the database into minimal building blocks of different type. The\nalgorithm is then trained to predict bond lengths and angles for each type of\nbuilding block using an electro-topological fingerprint as descriptor. A\nconformation is then generated by joining the predicted blocks. Our model is\nable to give promising results for optimized molecular geometries from the\nbasic knowledge of the chemical formula and connectivity. The method trends to\nreproduce interatomic distances within test blocks with RMSD under $0.05$ \\r{A}"
    },
    {
        "anchor": "Surface Chemical Reactivity of Ultrathin Pd(111) Films on Ru(0001):\n  Importance of Orbital Symmetry in the Application of the d-Band Model: The chemical bonding of adsorbate molecules on transition-metal surfaces is\nstrongly influenced by the hybridization between the molecular orbitals and the\nmetal d-band. The strength of this interaction is often correlated with the\nlocation of the metal d-band center relative to the Fermi level. Here, we\nexploit finite size effects in the electronic structure of ultrathin Pd(111)\nfilms grown on Ru(0001) to tune their reactivity by changing the film thickness\none atom layer at a time, while keeping all other variables unchanged.\nInterestingly, while bulk Pd(111) is reactive towards oxygen, Pd(111) films\nbelow five monolayers are surprisingly inert. This observation is fully in line\nwith the d-band model prediction when applied to the orbitals involved in the\nbonding. The shift of the d-band center with film thickness is primarily\nattributed to shifts in the partial density of states associated with the 4dxz\nand 4dyz orbitals. This study gives an in-depth look into the orbital specific\ncontributions to the surface chemical reactivity, providing new insights that\ncould be useful in surface catalysis.",
        "positive": "Multi-scale Modeling of Plasticity Nearby Precipitates in Nanostructured\n  Materials: Precipitation strengthening is one of the most effective methods to design\nalloys with the desired combination of strength and ductility. The main\nmechanism of strengthening is generally known to be the interaction between\ndislocations and precipitates. When a dislocation encounters a precipitate, it\nbends and therefore the level of applied stress to the precipitate increases.\nOnce the applied stress reaches the precipitate resistance, it passes the\nprecipitate. Dislocations can bypass precipitates either by forming the Orowan\nloops or by cutting them. In this research, the focus is set on a small domain\nnearby precipitates to investigate their effects on the effective plastic\nstrain. Both penetrable and impenetrable precipitates are considered. Two\nscales are coupled to model this phenomenon, the nano-micro scale where\nplasticity is determined by explicit three-dimensional discrete dislocation\ndynamics analysis and the continuum scale where the finite element method is\napplied. With this hybrid approach, complex problems in plastic deformation of\nnanostructured materials can be addressed. Finally, the relation between the\nprecipitate resistance and the effective plastic strain is investigated."
    },
    {
        "anchor": "Direct Experimental Evidence for the Hybridization of Organic Molecular\n  Orbitals with Substrate States at Interfaces: PTCDA on Silver: We demonstrate the application of orbital k-space tomography for the analysis\nof the bonding occurring at metal-organic interfaces. Using angle-resolved\nphotoelectron spectroscopy (ARPES), we probe the spatial structure of the\nhighest occupied molecular orbital (HOMO) and the former lowest unoccupied\nmolecular orbital (LUMO) of one monolayer\n3,4,9,10-perylenetetracarboxylic-dianhydride (PTCDA) on Ag(110) and (111)\nsurfaces and in particular the influence of the hybridization between the\norbitals and the electronic states of the substrate. We are able to quantify\nand localize the substrate contribution to the LUMO and thus prove the\nmetal-molecule hybrid character of this complex state.",
        "positive": "Going for Gold(-Standard): Attaining Coupled Cluster Accuracy in\n  Oxide-Supported Nanoclusters: Metal nanoclusters supported on oxide surfaces are widely-used catalysts that\nboasts sharply enhanced activity over their bulk, especially for the coinage\nmetals: Au, Ag and Cu. These properties depend sensitively on the nanocluster\nstructure, which are challenging to model with density functional theory (DFT)\n-- the workhorse modelling technique. Leveraging the recently developed SKZCAM\nprotocol, we perform the first ever benchmark study of coinage metal structures\non the MgO surface with coupled cluster theory [CCSD(T)] -- the gold-standard\nmodelling technique. We investigate a comprehensive range of DFT models\n(exchange-correlation functional and dispersion correction) and our benchmarks\nreveal that none of the investigated models can accurately describe this\nsystem. We demonstrate that this arises from inadequate account of metal-metal\ninteractions in the nanocluster and propose a high-level correction which\nprovides reference accuracy at low cost. This forges a path towards studying\nlarger systems, which we highlight by benchmarking Au$_{20}$ on MgO, a\nchallenging system where DFT models have disagreed on its ground state\nstructure."
    },
    {
        "anchor": "Generation and modulation of multiple 2D bulk photovoltaic effects in\n  space-time reversal asymmetric 2H-FeCl2: The two-dimensional (2D) bulk photovoltaic effect (BPVE) is a cornerstone for\nfuture highly efficient 2D solar cells and optoelectronics. The ferromagnetic\nsemiconductor 2H-FeCl2 is shown to realize a new type of BPVE in which spatial\ninversion (P), time reversal (T), and space-time reversal (PT) symmetries are\nbroken (PT-broken). Using density functional theory and perturbation theory, we\nshow that 2H-FeCl2 exhibits giant photocurrents, photo-spin-currents, and\nphoto-orbital-currents under illumination by linearly polarized light. The\ninjection-like and shift-like photocurrents coexist and propagate in different\ndirections. The material also demonstrates substantial photoconductance,\nphoto-spin-conductance, and photo-orbital-conductance, with magnitudes up to\n4650 (nm{\\cdot}{\\mu}A/V2), 4620 (nm{\\cdot}{\\mu}A/V2 {\\hbar}/2e), and 6450\n(nm{\\cdot}{\\mu}A/V2 {\\hbar}/e), respectively. Furthermore, the\ninjection-currents, shift-spin-currents, and shift-orbital-currents can be\nreadily switched via rotating the magnetizations of 2H-FeCl2. These results\ndemonstrate the superior performance and intriguing control of a new type of\nBPVE in 2H-FeCl2.",
        "positive": "Experimental and analytical insights on fracture trajectories in brittle\n  materials with voids: Analytical models have been developed for fracture propagation over the last\nseveral decades and are now considered with renewed interest; the range of\ntheir applicability varies for different materials and different loading\nconditions. Systematic experimental measurements and numerical simulations are\npresented against an asymptotic prediction for the crack trajectory developing\nin solids with small voids (of circular and elliptical shape). The experiments\nalso cover the dynamic regime, where new features involving crack kinking and\nroughness of the fracture surface occur."
    },
    {
        "anchor": "Spin-resolved off-specular neutron scattering from magnetic domain walls\n  using the polarized $^3He$ gas spin filter: We report on the use of the polarized $^3$He gas filter and neutron resonant\nenhancement techniques for the measurement of spin-polarized diffuse neutron\nscattering due to ferromagnetic domains. A CoO/Co exchange biased bilayer was\ngrown on a Ti/Cu/$Al_2O_3$ neutron resonator template. The system is cooled in\nan applied magnetic field of $H_a=2000$ Oe through the N\\'{e}el temperature of\nthe antiferromagnet to 10 K where the applied magnetic field is swept as to\nmeasure the magnetic hysteresis loop. After the second magnetization reversal\nat the coercive field $H_{c2}=+ 230$ Oe, the system is supposed to approach the\noriginal magnetic configuration. In order to prove that this is not the case\nfor our exchange biased bilayer, we have measured four off-specular maps I++,\nI+-, I-+, I-- at $H_a \\approx + 370$ Oe, where the Co magnetic spins were\nmostly reversed. They show a striking behavior in the total reflection region:\nwhile the nonspin-flip scattering exhibits no diffuse reflectivity, the\nspin-flip scattering shows strong diffuse scattering at incident angles which\nsatisfy the resonance conditions. Moreover the spin-flip off-specular part of\nthe reflectivity is asymmetric. The I-+ intensity occurs at higher exit angles\nthan the specularly reflected neutrons, and the I+- intensity is shifted to\nlower angles. Their intensities are noticeably different and there is a\nsplitting of the resonance positions for the up and down neutron spins\n($\\alpha_{n} ^{+} \\ne \\alpha_{n} ^{-}$) . Additionally, a strong influence of\nthe stray fields from magnetic domains to the resonance splitting is observed.",
        "positive": "Control of ternary alloy composition during remote epitaxy on graphene: Understanding the sticking coefficient $\\sigma$, i.e., the probability of an\nadatom sticking to a surface, is essential for controlling the stoichiometry\nduring epitaxial film growth. However, $\\sigma$ on monolayer graphene-covered\nsurfaces and its impact on remote epitaxy are not understood. Here, using\nmolecular-beam epitaxial (MBE) growth of the magnetic shape memory alloy\nNi$_2$MnGa, we show that the sticking coefficients for metals on\ngraphene-covered MgO (001) are less than one and are temperature and element\ndependent, as revealed by ion backscattering spectrometry (IBS) and energy\ndispersive x-ray spectroscopy (EDS). This lies in stark contrast with most\ntransition metals sticking on semiconductor and oxide substrates, for which\n$\\sigma$ is near unity at typical growth temperatures ($T<800\\degree$C). By\ninitiating growth below $400 \\degree$ C, where the sticking coefficients are\ncloser to unity and wetting on the graphene surface is improved, we demonstrate\nepitaxy of Ni$_2$MnGa films with controlled stoichiometry that can be\nexfoliated to produce freestanding membranes. Straining these membranes tunes\nthe magnetic coercive field. Our results provide a route to synthesize\nmembranes with complex stoichiometries whose properties can be manipulated via\nstrain."
    },
    {
        "anchor": "Nanoengineered Curie Temperature in Laterally-Patterned Ferromagnetic\n  Semiconductor Heterostructures: We demonstrate the manipulation of the Curie temperature of buried layers of\nthe ferromagnetic semiconductor (Ga,Mn)As using nanolithography to enhance the\neffect of annealing. Patterning the GaAs-capped ferromagnetic layers into\nnanowires exposes free surfaces at the sidewalls of the patterned (Ga,Mn)As\nlayers and thus allows the removal of Mn interstitials using annealing. This\nleads to an enhanced Curie temperature and reduced resistivity compared to\nunpatterned samples. For a fixed annealing time, the enhancement of the Curie\ntemperature is larger for narrower nanowires.",
        "positive": "Nanoscale control of exchange bias with BiFeO3 thin films: We demonstrate a direct correlation between the domain structure of\nmultiferroic BiFeO3 thin films and exchange bias of Co0.9Fe0.1/BiFeO3\nheterostructures. Two distinct types of interactions, an enhancement of the\ncoercive field (exchange enhancement) and an enhancement of the coercive field\ncombined with large shifts of the hysteresis loop (exchange bias), have been\nobserved in these heterostructures, which depend directly on the type and\ncrystallography of the nanoscale (2 nm) domain walls in the BiFeO3 film. We\nshow that the magnitude of the exchange bias interaction scales with the length\nof 109 degree ferroelectric domain walls in the BiFeO3 thin films which have\nbeen probed via piezoresponse force microscopy and x-ray magnetic circular\ndichroism."
    },
    {
        "anchor": "Revealing two heat-annealing related photoproduct systems and widely\n  existed subgrain domains in organolead perovskite: For highly interested organolead perovskite based solar cells, the\nphotoproducts are regarded as the co-existed exciton and free carriers. In this\nstudy, we carefully re-examined this conclusion with our recently developed\ndensity-resolved spectroscopic method. Heat-annealing related two photoproduct\nsystems are observed. We found that the widely accepted model is only true for\nsingle crystal and freshly made films without heat-annealing. For those\nsufficiently heat-annealed films, another system presenting significant\nemissive exciton-carrier collision (ECC) is discovered. In addition, the\nappearing of ECC indicates the emerging of an internal morphology after heat\nannealing, which is assigned to a recently discussed twinning subgrain\nstructure. We proved that such subgrain structures broadly exist in perovskite\nfilms. This finding could prove the morphological basis for high performance of\nperovskite working layers.",
        "positive": "CaCu3Ti4O12 (CCTO) ceramics for capacitor applications: CaCu3Ti4O12 (CCTO) ceramics are potential candidates for capacitor\napplications due to their large dielectric permittivity (e') values of up to\n300 000. The underlying mechanism for the high e' is an internal barrier layer\ncapacitor (IBLC) structure of insulating grain boundaries (GB) and conducting\ngrain interiors (bulk). This behaviour is reviewed and discussed in detail. The\norigin of the IBLC structure is attributed to a small Cu non-stoichiometry in\nnominally insulating CaCu3Ti4O12, which varies between the GBs and bulk. Such\nnon-stoichiometry effects are studied in detail by analyzing bulk ceramics of\ndifferent composition within the ternary CaO-CuO-TiO2 phase diagram using X-ray\ndiffraction (XRD), scanning electron microscopy (SEM) and impedance\nspectroscopy (IS). At least two defect mechanisms are suggested to exist. It is\nfurther shown that the development of the defect mechanisms in CCTO and the\nconcomitant formation of the IBLC structure strongly depend on the processing\nconditions of CCTO ceramic pellets such as the sintering temperature. Nominally\nstoichiometric CCTO bulk ceramics sintered at different temperatures are\nanalyzed using XRD, SEM and IS. The performance of CCTO ceramics for IBLC\napplications is controlled by subtle modifications in the compound\nstoichiometry that is strongly dependent on the ceramic sintering temperature."
    },
    {
        "anchor": "Lattice-dynamics and in-plane antiferromagnetism in MnxZn1_xPS3 across\n  the entire composition range: Alloyed MnxZn1_xPS3 samples have been grown covering the whole compositional\nrange and studied by means of Raman spectroscopy at temperatures covering from\n4K up to 850K. Our results, supported by SQUID magnetic measurements, allowed,\nfrom one hand, to complete the magnetic phase diagram of MnxZn1_xPS3 and\nestablish x>0.3 as the composition at which the alloy retains\nantiferromagnetism and, from the other hand, to identify the Raman signatures\nindicative of a magnetic transition. The origin of these Raman signatures is\ndiscussed in terms of spin-phonon coupling resulting in the appearance of low-\nand high-frequency zone-folded phonon modes. For the alloy, an assignment of\nthe 1st and 2nd order modes is provided with the aid of first-principle\nlattice-dynamical calculations. The compositional dependence of all phonon\nmodes is described and the presence of zone-folded modes is shown to take place\nfor both, the alloy and MnPS3. Finally, a comparison of the Raman spectra of\nZnPS3 to other compounds of the transition-metal phosphorous trisulfide family\nallowed shows that low-frequency phonon peaks exhibit an abnormally large\nbroadening. This is consistent with previous claims on the occurrence of a\nsecond-order Jahn-Teller effect that takes place for ZnPS3 and Zn-rich\nMnxZn1_xPS3.",
        "positive": "Graphene induced tunability of the surface plasmon resonance: Tunability of the surface plasmon resonance wavelength is demonstrated by\nvarying the thickness of Al2O3 spacer layer inserted between the graphene and\nnanoparticles. By varying the spacer layer thickness from 0.3 to 1.8 nm, the\nresonance wavelength is shifted from 583 to 566 nm. The shift is due to a\nchange in the electromagnetic field coupling strength between the localized\nsurface plasmons excited in the gold nanoparticles and a single layer graphene\nfilm. In contrast, when the graphene film is absent from the system, no\nnoticeable shift in the resonance wavelength is observed upon varying the\nspacer thickness."
    },
    {
        "anchor": "Sexiphenyl on Cu(100): nc-AFM tip functionalization and identification: The contrast obtained in scanning tunneling microscopy (STM) and atomic force\nmicroscopy (AFM) images is determined by the tip termination and symmetry.\nFunctionalizing the tip with a single metal atom, CO molecule or organic\nspecies has been shown to provide high spatial resolution and insights into\ntip-surface interactions. A topic where this concept is utilized is the\nadsorption of organic molecules at surfaces. With this work we aim to\ncontribute to the growing database of organic molecules that allow assignment\nby intra-molecular imaging. We investigated the organic molecule\npara-sexiphenyl (C36H26, 6P) on Cu(100) using low-temperature STM and\nnon-contact AFM with intra-molecular resolution. In the sub-monolayer regime we\nfind a planar and flat adsorption with the 6P molecules rotated 10{\\deg} off\nthe <010> directions. In this configuration, four of the six phenyl rings\noccupy almost equivalent sites on the surface. The 6P molecules are further\ninvestigated with CO- functionalized tips, in comparison to a single-atom metal\nand 6P-terminated tip. We also show that the procedure of using adsorbed CO to\ncharacterize tips introduced by Hofmann et al. Phys. Rev. B 112 (2014) 066101\nis useful when the tip is terminated with an organic molecule.",
        "positive": "Theory of composite-band Wannier states and order-N electronic-structure\n  calculations: From the order-N electronic-structure formulation, a Hamiltonian is derived,\nof which lowest eigen state is the generalized or composite-band Wannier state.\nThis Hamiltonian maps the locality of the Wannier state to that of a virtual\nimpurity state and to a perturbation from a bonding orbital. These theories are\ndemonstrated in the diamond-structure solids, where the Wannier states are\nconstructed by a practical order-N algorithm with the Hamiltonian. The results\ngive a prototypical picture of the Wannier states in covalent-bonded systems."
    },
    {
        "anchor": "Polydopamine-Coated TiO2 Nanotubes for Selective Photocatalytic\n  Oxidation of Benzyl Alcohol to Benzaldehyde under Visible Light: TiO2 nanotube arrays grown by anodization were coated with thin layers of\npolydopamine as visible light sensitizer. The PDA-coated TiO2 scaffolds were\nused as photocatalyst for selective oxidation of benzyl alcohol under\nmonochromatic irradiation at 473 nm. Benzaldehyde was selectively formed and no\nby-products could be detected. A maximized reaction yield was obtained in\nO2-saturated acetonitrile. A mechanism is proposed that implies firstly the\ncharge carrier generation in polydopamine as a consequence of visible light\nabsorption. Secondly, photo-promoted electrons are injected in TiO2 conduction\nband, and subsequently transferred to dissolved O2 to form oxygen radical\nanions. These radicals react with benzyl alcohol and lead to its selective\ndehydrogenation oxidation towards benzaldehyde.",
        "positive": "Quantifying work function differences using low-energy electron\n  microscopy: the case of mixed-terminated strontium titanate: For many applications, it is important to measure the local work function of\na surface with high lateral resolution. Low-energy electron microscopy is\nregularly employed to this end since it is, in principle, very well suited as\nit combines high-resolution imaging with high sensitivity to local\nelectrostatic potentials. For surfaces with areas of different work function,\nhowever, lateral electrostatic fields inevitably associated with work function\ndiscontinuities deflect the low-energy electrons and thereby cause artifacts\nnear these discontinuities. We use ray-tracing simulations to show that these\nartifacts extend over hundreds of nanometers and cause an overestimation of the\ntrue work function difference near the discontinuity by a factor of 1.6 if the\nstandard image analysis methods are used. We demonstrate on a mixed-terminated\nstrontium titanate surface that comparing LEEM data with detailed ray-tracing\nsimulations leads to much a more robust estimate of the work function\ndifference."
    },
    {
        "anchor": "Impurity scattering in the bulk of topological insulators: We study in this paper time-reversal $\\delta$-impurity scattering effects in\nthe bulk of topological insulators (TI) in two and three dimensions.\nSpecifically we consider how impurity scattering strength is affected by the\nbulk band structure of topological insulators. An interesting band inversion\neffect associated with the change of the system from ordinary to topological\ninsulator is pointed out. Experimental consequences of our findings are\ndiscussed.",
        "positive": "Simulation of ion demixing in halide perovskites using Cahn-Hilliard\n  equation: Light-induced ion demixing in mixed-halide perovskites is simulated\nnumerically using the phenomenological Cahn-Hilliard equation. In the model we\nconsider the energy of local elastic deformation as well as the contribution of\nfree carriers, assuming both the polaron and the bandgap-fluctuation models.\nThe simulation shows that elastic deformation suppresses the demixing while\nfree carriers promote it, however both effects lead to different ion\ndistributions. The free-carrier-induced demixing appears only for larger\nstarting random fluctuations of the ion concentration."
    },
    {
        "anchor": "Implementation of the SCAN Exchange-Correlation Functional with\n  Numerical Atomic Orbitals: Kohn-Sham density functional theory (DFT) is nowadays widely used for\nelectronic structure theory simulations, and the accuracy and efficiency of DFT\nrely on approximations of the exchange-correlation functional. By inclusion of\nthe kinetic energy density $\\tau$, the meta-generalized-gradient approximation\n(meta-GGA) family of functionals achieves better accuracy and flexibility while\nretaining the efficiency of semi-local functionals. The SCAN meta-GGA\nfunctional has been proven to yield accurate results for solid and molecular\nsystems. We implement meta-GGA functionals with both numerical atomic orbitals\nand plane wave basis in the ABACUS package. Apart from the exchange-correlation\npotential, we also discuss the evaluation of force and stress. To validate our\nimplementation, we perform finite-difference tests and convergence tests with\nthe SCAN meta-GGA functional. We further test water hexamers, weakly\ninteracting molecules of the S22 dataset, as well as 13 semiconductors. The\nresults show satisfactory agreements with previous calculations and available\nexperimental values.",
        "positive": "Atomic motion in solids with dimpled potentials: Polymorphic solids of the same chemical composition can have different atomic\nstructures; in each polymorph atoms vibrate around a local potential energy\nminimum (LPEM). If transformations to other structures have sufficiently high\nenthalpy barriers, then each polymorph is either stable or metastable; it is\nstationary and does not spontaneously change with time. But what happens, if\nthose barriers are low? As examples, we consider NiTi shape memory alloy\nexhibiting a large elastocaloric effect, and selected elemental solids. We\nsuggest a model for dynamically polymorphic solids, where multiple LPEMs are\nvisited by ergodic motion of a single atom. We predict that upon cooling a\ndynamically polymorphic phase should undergo a symmetry-breaking first-order\nphase transition, accompanied by a finite change of the lattice entropy. We\ndiscuss 3 methods used to calculate phonons in solids with non-harmonic dimpled\natomic potentials, and compare theoretical predictions to experiment."
    },
    {
        "anchor": "Low energy exciton pocket at finite momentum in tetracene molecular\n  solids: The excited state dynamics in organic semiconductors plays an important role\nfor many processes associated with light absorption and emission. We have\nstudied the momentum dependence of the lowest singlet excitons in tetracene\nmolecular solids, an archetype system for other organic semiconductors. Our\nresults reveal an anisotropic bandstructure of these excitons with an energy\nminimum at finite momentum, i. e., a low energy exciton pocket. The existence\nof such low energy states might have important consequences for the\nphotophysical behavior, also in view of applications in, e. g., organic solar\ncells. Our studies stress the importance of momentum dependent considerations\nin organic systems.",
        "positive": "Band gaps in pseudopotential self-consistent GW calculations: For materials which are incorrectly predicted by density functional theory to\nbe metallic, an iterative procedure must be adopted in order to perform GW\ncalculations. In this paper we test two iterative schemes based on the\nquasi-particle and pseudopotential approximations for a number of inorganic\nsemiconductors whose electronic structures are well known from experiment.\nIterating just the quasi-particle energies yields a systematic, but modest\noverestimate of the band gaps, confirming conclusions drawn earlier for CaB_6\nand YH_3. Iterating the quasi-particle wave functions as well gives rise to an\nimbalance between the Hartree and Fock potentials and results in bandgaps in\nfar poorer agreement with experiment."
    },
    {
        "anchor": "Differentiable thermodynamic modeling: A new framework of thermodynamic modeling is proposed by introducing the\nconcept of differentiable programming, where all the thermodynamic observables\nincluding both thermochemical quantities and phase equilibria can be\ndifferentiated with respect to the underlying model parameters, thus allowing\nthe models learned by gradient-based optimization. It is shown that\nthermodynamic modeling and deep learning can be seamlessly integrated and\nunified within this framework. A preliminary successful application is\ndemonstrated for the Cu-Rh system. It is expected that thermodynamic modeling\nin a deep learning style can increase prediction power of models, and provide\nmore effective guidance for design, synthesis and optimization of\nmulti-component materials with complex chemistry via learning various types of\ndata.",
        "positive": "Gamma-irradiation influence on the initial magnetic conductivity of\n  based on the system Fe-Si-B amorphous and nanocrystalline alloys: The dependence of initial magnetic permeability {\\mu}i of based on the\nFe-Si-B amorphous and nanocrystalline alloys on the {\\gamma}-irradiation dose\nwas investigated by the method of inductance factor determination. It was\ndetermined that the alloying of amorphous Fe-Si-B alloys by nickel and\nmolybdenum increases the radiation sensitivity of the {\\mu}i. Initial magnetic\npermeability of nanocrystalline magnetic alloys is less sensitive to the action\nof {\\gamma}-irradiation as compared with the alloyed amorphous alloys. Has been\nsuggested that radiation influence on the initial magnetic permeability are\ncaused by creation of non-magnetic incorporation in structure of amorphous\nalloys as well as amorphous matrix of nanocrystalline alloys."
    },
    {
        "anchor": "A many-body GW+BSE investigation of electronic and optical properties of\n  C2N: A newly synthesized layered material C2N was investigated based on many- body\nperturbation theory using GW plus Bethe-Salpeter equation approach. The\nelectronic band gap was determined to be ranging from 3.75 to 1.89 eV from\nmonolayer to bulk. Significant GW quasiparticle corrections, of more than 0.9\neV, to the Kohn-Sham band gaps from the local density approximation (LDA)\ncalculations are found. Strong excitonic effects play a crucial role in optical\nproperties. We found large binding energies of greater than 0.6 eV for bound\nexcitons in few-layer C2N, while it is only 0.04 eV in bulk C2N. All the\nstructures exhibit strong and broad optical absorption in the visible light\nregion, which makes C2N a promising candidate for solar energy conversion, such\nas photocatalytic water splitting.",
        "positive": "Effects of the local chemical environment on vacancy diffusion in\n  multi-principal element alloys: Multi-principal element alloys (MPEAs) are exciting systems showing\nremarkable properties compared to conventional materials due to their\nexceedingly large compositional space and spatially varying chemical\nenvironment. However, predicting fundamental properties from the local chemical\nenvironment is challenging due to the large scale of the problem. To\ninvestigate this fundamental problem, we employ a combination of atomistic\nsimulations (using ab-initio and molecular dynamics) and convolutional neural\nnetworks (CNNs) to evaluate point defect and migration energies in an equimolar\nCoFeCrNi MPEA. We show how energies of point defects can be predicted with\nreasonable accuracy using a small subset of local chemical environments. Using\nthe CNNs, we develop a lattice Monte Carlo simulation that computes the\nmigration path and diffusivities of vacancies. Remarkably, our work illustrates\nhow the local chemical environment leads rise to a distribution function of the\npoint defect energies, which is responsible for the macroscopic diffusivity of\nvacancies. In particular, we observed that vacancies get trapped in super\nbasins surrounded by large migration and connected with low migration energy\nstates. As a result, vacancy diffusivity is highly dependent on the environment\nand could change several orders of magnitude for a given temperature. Our works\nillustrate the importance of understanding properties in MPEAs depending on the\nlocal chemical environment and the ability of CNN to provide a model for\ncomputing energies in high-dimensional spaces, which can be used to scale\nthings up to higher-order models."
    },
    {
        "anchor": "Terahertz Optics Driven Phase Transition in Two-Dimensional\n  Multiferroics: Displacive martensitic phase transition is potentially promising in\nsemiconductor based data storage applications with fast switching speed. In\naddition to traditional phase transition materials, the recently discovered\ntwo-dimensional ferroic materials are receiving lots of attention owing to\ntheir fast ferroic switching dynamics, which could tremendously boost data\nstorage density and enhance read/write speed. In this study, we propose that a\nterahertz laser with an intermediate intensity and selected frequency can\ntrigger ferroic order switching in two-dimensional multiferroics, which is a\ndamage-free noncontacting approach. Through first-principles calculations, we\ntheoretically and computationally investigate optically induced electronic,\nphononic, and mechanical responses of two experimentally fabricated\nmultiferroic (with both ferroelastic and ferroelectric) materials, \\b{eta}-GeSe\nand {\\alpha}-SnTe monolayer. We show that the relative stability of different\norientation variants can be effectively manipulated via the polarization\ndirection of the terahertz laser, which is selectively and strongly coupled\nwith the transverse optical phonon modes. The transition from one orientation\nvariant to another can be barrierless, indicating ultrafast transition kinetics\nand the conventional nucleation-growth phase transition process can be\navoidable.",
        "positive": "Fine structure of the band edge excitons and trions in CdSe/CdS\n  core/shell nanocrystals: We present a theoretical description of excitons and positively and\nnegatively charged trions in \"giant\" CdSe/CdS core-shell nanocrystals (NCs).\nThe developed theory provides the parameters describing the fine structure of\nexcitons in CdSe/CdS core/thick shell NCs as a function of the CdSe/CdS\nconduction band offset and the CdSe core radius. We have also developed a\ngeneral theory describing the fine structure of positively charged trions\ncreated in semiconductor NCs with a degenerate valence band. The calculations\ntake into account the complex structure of the CdSe valence band and\ninter-particle Coulomb and exchange interaction. Presented in this paper are\nthe CdSe core size and CdSe/CdS conduction band offset dependences (i) of the\npositively charged trion fine structure, (ii) of the binding energy of the\nnegatively charged trion, and (iii) of the radiative decay time for excitons\nand trions. The results of theoretical calculations are in qualitative\nagreement with available experimental data."
    },
    {
        "anchor": "A real-space grid implementation of the Projector Augmented Wave method: A grid-based real-space implementation of the Projector Augmented Wave (PAW)\nmethod of P. E. Blochl [Phys. Rev. B 50, 17953 (1994)] for Density Functional\nTheory (DFT) calculations is presented. The use of uniform 3D real-space grids\nfor representing wave functions, densities and potentials allows for flexible\nboundary conditions, efficient multigrid algorithms for solving Poisson and\nKohn-Sham equations, and efficient parallelization using simple real-space\ndomain-decomposition. We use the PAW method to perform all-electron\ncalculations in the frozen core approximation, with smooth valence wave\nfunctions that can be represented on relatively coarse grids. We demonstrate\nthe accuracy of the method by calculating the atomization energies of twenty\nsmall molecules, and the bulk modulus and lattice constants of bulk aluminum.\nWe show that the approach in terms of computational efficiency is comparable to\nstandard plane-wave methods, but the memory requirements are higher.",
        "positive": "Scale-dependent optimized homoepitaxy of InAs(111)A: We combined in-situ scanning tunneling microscopy (STM) with the conventional\ngrowth characterization methods of atomic force microscopy (AFM) and reflection\nhigh energy electron diffraction (RHEED) to simultaneously assess atomic-scale\nimpurities and the larger-scale surface morphology of molecular beam epitaxy\n(MBE) grown homoepitaxial InAs(111)A. By keeping a constant substrate\ntemperature and indium flux while increasing the As$_2$ flux, we find two\ndiffering MBE growth parameter regions for optimized surface roughness on the\nmacro and atomic scale. In particular, we show that a pure step-flow regime\nwith strong suppression of hillock formation can be achieved, even on\nsubstrates without intentional offcut. On the other hand, an indium adatom\ndeficient, low atomic defect surface can be observed for a high hillock\ndensity. We identify the main remaining point defect on the latter surface by\ncomparison to STM simulations. Furthermore, we provide a method for extracting\nroot-mean-square surface roughness values and discuss their use for surface\nquality optimization by comparison to scale-dependent, technologically relevant\nsurface metrics. Finally, mapping the separately optimized regions of the\ngrowth parameter space should provide a guide for future device engineering\ninvolving epitaxial InAs(111)A growth."
    },
    {
        "anchor": "Atomically Sharp Internal Interface in a Chiral Weyl Semimetal Nanowire: Internal interfaces in Weyl semimetals (WSMs) are predicted to host distinct\ntopological features that are different from the commonly studied external\ninterfaces (crystal-to-vacuum boundaries). However, the lack of atomically\nsharp and crystallographically oriented internal interfaces in WSMs makes it\ndifficult to experimentally investigate hidden topological states buried inside\nthe material. Here, we study a unique internal interface known as merohedral\ntwin boundary in chemically synthesized single-crystal nanowires (NWs) of CoSi,\na chiral WSM of space group P213 (No. 198). High resolution scanning\ntransmission electron microscopy reveals that this internal interface is (001)\ntwin plane and connects two enantiomeric counterparts at an atomically sharp\ninterface with inversion twinning. Ab-initio calculations show localized\ninternal Fermi arcs at the (001) twin boundary that can be clearly\ndistinguished from both external Fermi arcs and bulk states. These merohedrally\ntwinned CoSi NWs provide an ideal material system to probe unexplored\ntopological properties associated with internal interfaces in WSMs.",
        "positive": "Ewald summation for ferroelectric perovskites with charges and dipoles: Ewald summation is an important technique used to deal with long-range\nCoulomb interaction. While it is widely used in simulations of molecules and\nsolid state materials, many important results are dispersed in literature and\ntheir implementations are often buried deep in large software packages. Since\nreliable and systematic calculation of Coulomb interaction is critical for the\ninvestigation of perovskites, here we start from the fundamentals of Ewald\nsummation and derive clear expressions for long-range charge-charge,\ndipole-dipole, and charge-dipole interactions, which can be readily used for\nnumerical computations. We also provide the interaction matrix for efficient\nMonte Carlo simulations involving charges and dipoles, implementing them in a\nPython software package. A new type of interaction matrix, which accounts for\nthe electrostatic energy change when ions are displaced, is also derived and\nimplemented. These results are the foundations for the investigation of\nferroelectric perovskites."
    },
    {
        "anchor": "CTZS Thin Films Grown by a Sequential Deposition of Precursors: A comparative study of the structural, optical and morphological properties\nof Cu2ZnSnS4 (CZTS) thin films prepared by two different techniques was\nperformed. One consists of sequential evaporation of the elemental metallic\nprecursors under a flux of sulphur supplied by evaporation from an effusion\ncell (physical vapor deposition-PVD) and the second one is a solution-based\nchemical route where thin layers of CuS, SnS and ZnS are deposited sequentially\nby diffusion membrane- assisted chemical bath deposition techniques; the\nmembranes are used to optimize the kinetic growth through a moderate control of\nthe release of the metal into CBD solution by osmosis. The present comparative\nstudy is helpful to the synthesis of kesterite nanostructured thin films.",
        "positive": "Hysteretic \"Magnetic-Transport-Structural\" Transition in \"114\"\n  Cobaltites: Size Mismatch Effect: The triple \"magnetic-transport-structural\" transition versus temperature in\nthree series of \"114\" cobaltites - Y1-xYbxBaCo4O7, Y1-xCaxBaCo4O7 and\nYb1-xCaxBaCo4O7 - has been studied using magnetic, transport and differential\nscanning calorimetric measurements. The effect of the size mismatch {\\sigma}2,\ndue to cationic disordering at the Ln sites upon such a transition is shown for\nthe first time in a triangular lattice. We show that increasing <rLn> has an\neffect of increasing TS dramatically, while the size mismatch {\\sigma}2 at the\nLn sites decreases TS substantially. Moreover, the cationic mismatch at the Ln\nsites modifies the nature of the hysteretic transition by turning the sharp\nfirst order transition seen in the undoped samples into an intermix of first\nand second order transitions. These results are discussed on the basis of the\nparticular nature of the high temperature form which exhibits a hexagonal close\npacked structure (space group: P63mc) with respect to the low temperature\northorhombic form (space group: Pbn21), the latter corresponding to a\ndistortion of the former due to a puckering of the kagom\\'e layers."
    },
    {
        "anchor": "Microscopic insights on field induced switching and domain wall motion\n  in orthorhombic ferroelectrics: Surprisingly little is known about the microscopic processes that govern\nferroelectric switching in orthorhombic ferroelectrics.\n  To study microscopic switching processes we combine ab initio-based molecular\ndynamics simulations and data science on the prototypical material BaTiO$_3$.\nWe reveal two different field regimes: For moderate field strengths, the\nswitching is dominated by domain wall motion while a fast bulk-like switching\ncan be induced for large fields. Switching in both field regimes follows a\nmulti-step process via polarization directions perpendicular to the applied\nfield. In the former case, the moving wall is of Bloch character and hosts\ndipole vortices due to nucleation, growth, and crossing of two dimensional\n90$^{\\circ}$ domains. In the second case, the local polarization shows a\ncontinuous correlated rotation via a an intermediate tetragonal multidomain\nstate.",
        "positive": "Perpendicular magnetic anisotropy in Pt/Co-based full Heusler alloy/MgO\n  thin films structures: Perpendicular magnetic anisotropy (PMA) in ultrathin magnetic structures is a\nkey ingredient for the development of electrically controlled spintronic\ndevices. Due to their relatively large spin-polarization, high Curie\ntemperature and low Gilbert damping the Co-based full Heusler alloys are of\nspecial importance from a scientific and applications point of view. Here, we\nstudy the mechanisms responsible for the PMA in Pt/Co-based full Heusler\nalloy/MgO thin films structures. We show that the ultrathin Heusler films\nexhibit strong PMA even in the absence of magnetic annealing. By means of\nferromagnetic resonance experiments, we demonstrate that the effective\nmagnetization shows a two-regime behavior depending on the thickness of the\nHeusler layers. Using Auger spectroscopy measurements, we evidence\ninterdiffusion at the underlayer/Heusler interface and the formation of an\ninterfacial CoFe-rich layer which causes the two-regime behavior. In the case\nof the ultrathin films, the interfacial CoFe-rich layer promotes the strong PMA\nthrough the electronic hybridization of the metal alloy and oxygen orbitals\nacross the ferromagnet/MgO interface. In addition, the interfacial CoFe-rich\nlayer it is also generating an increase of the Gilbert damping for the\nultrathin films beyond the spin-pumping effect. Our results illustrate that the\nstrong PMA is not an intrinsic property of the Heusler/MgO interface but it is\nactively influenced by the interdiffusion, which can be tuned by a proper\nchoice of the underlayer material, as we show for the case of the Pt, Ta and Cr\nunderlayers."
    },
    {
        "anchor": "Electronic, structural, and elastic properties of metal nitrides XN (X =\n  Sc, Y): A first principle study: We utilized a simple, robust, first principle method, based on basis set\noptimization with the BZW-EF method, to study the electronic and related\nproperties of transition metal mono-nitrides: ScN and YN. We solved the KS\nsystem of equations self-consistently within the linear combination of atomic\norbitals (LCAO) formalism. It is shown that the band gap and low energy\nconduction bands, as well as elastic and structural properties, can be\ncalculated with a reasonable accuracy when the LCAO formalism is used to obtain\nan optimal basis. Our calculated, indirect electronic band gap\n(E$^\\mathrm{\\Gamma-X}_g$) is 0.79 (LDA) and 0.88 eV (GGA) for ScN. In the case\nof YN, we predict an indirect band gap (E$^\\mathrm{\\Gamma-X}_g$) of 1.09 (LDA)\nand 1.15 eV (GGA). We also calculated the equilibrium lattice constants, the\nbulk moduli (B$_{o}$), effective masses, and elastic constants for both\nsystems. Our calculated values are in excellent agreement with experimental\nones where the latter are available.",
        "positive": "Gate-tunable spin-charge conversion and a role of spin-orbit interaction\n  in graphene: The small spin-orbit interaction of carbon atoms in graphene promises a long\nspin diffusion length and potential to create a spin field-effect transistor.\nHowever, for this reason, graphene was largely overlooked as a possible\nspin-charge conversion material. We report electric gate tuning of the\nspin-charge conversion voltage signal in a single-layer graphene. Using spin\npumping from yttrium iron garnet ferrimagnetic insulator and ionic liquid top\ngate we determined that the inverse spin Hall effect is the dominant\nspin-charge conversion mechanism in a single-layer graphene. From the gate\ndependence of the electromotive force we showed dominance of the intrinsic over\nRashba spin-orbit interaction: a long-standing question in graphene research."
    },
    {
        "anchor": "Conductance switching in a molecular device: the role of sidegroups and\n  intermolecular interactio: We report first-principles studies of electronic transport in monolayers of\nTour wires functionalized with different side groups. An analysis of the\nscattering states and transmission eigenchannels suggests that the\nfunctionalization does not strongly affect the resonances responsible for\ncurrent flow through the monolayer. However, functionalization has a\nsignificant effect on the interactions within the monolayer, so that monolayers\nwith NO$_2$ side groups exhibit local minima associated with twisted\nconformations of the molecules. We use our results to interpret observations of\nnegative differential resistance and molecular memory in monolayers of NO$_2$\nfunctionalized molecules in terms of a twisting of the central ring induced by\nan applied bias potential.",
        "positive": "High-throughput screening of metal-porphyrin-like graphenes for\n  selective capture of carbon dioxide: Nano-materials, such as metal-organic frameworks, have been considered to\ncapture CO$_2$. However, their application has been limited largely because\nthey exhibit poor selectivity for flue gases and low capture capacity under low\npressures. We perform a high-throughput screening for selective CO$_2$ capture\nfrom flue gases by using first principles thermodynamics. We find that elements\nwith empty d orbitals selectively attract CO$_2$ from gaseous mixtures under\nlow CO$_2$ pressures at 300 K and release it at ~450 K. CO$_2$ binding to\nelements involves hybridization of the metal d orbitals with the CO$_2$ $\\pi$\norbitals and CO$_2$-transition metal complexes were observed in experiments.\nThis result allows us to perform high-throughput screening to discover novel\npromising CO$_2$ capture materials with empty d orbitals and predict their\ncapture performance under various conditions. Moreover, these findings provide\nphysical insights into selective CO$_2$ capture and open a new path to explore\nCO$_2$ capture materials."
    },
    {
        "anchor": "Band gap analysis and carrier localization in cation-disordered\n  ZnGeN$_2$: Cation site disorder provides a degree of freedom in the growth of ternary\nnitrides for tuning the technologically relevant properties of a material\nsystem. For example, the band gap of ZnGeN$_2$ changes when the ordering of the\nstructure deviates from that of its ground state. By combining the perspectives\nof carrier localization and defect states, we analyze the impact of different\ndegrees of disordering on electronic properties in ZnGeN$_2$, addressing a gap\nin current studies which focus on dilute or fully disordered systems. The\npresent study demonstrates changes in the density of states and localization of\ncarriers in ZnGeN$_2$ calculated using band gap-corrected density functional\ntheory and hybrid calculations on partially disordered supercells generated\nusing the Monte Carlo method. We use localization and density of states to\ndiscuss the ill-defined nature of a band gap in a disordered material,\ncomparing multiple definitions of the energy gap in the context of theory and\nexperiment. Decreasing the order parameter results in a large reduction of the\nband gap in disordered cases. The reduction in band gap is due in part to\nisolated, localized states that form above the valence band continuum and are\nassociated with nitrogen coordinated by more zinc than germanium. The\nprevalence of defect states in all but the perfectly ordered structure creates\nchallenges for incorporating disordered ZnGeN$_2$ into optical devices, but the\nlocalization associated with these defects provides insight into mechanisms of\nelectron/hole recombination in the material.",
        "positive": "Single Crystal Sapphire at milli-Kelvin Temperatures: Observation of\n  Electromagnetically Induced Thermal Bistability in High Q-factor Whispering\n  Gallery Modes: Resonance modes in single crystal sapphire ($\\alpha$-Al$_2$O$_3$) exhibit\nextremely high electrical and mechanical Q-factors ($\\approx 10^9$ at 4K),\nwhich are important characteristics for electromechanical experiments at the\nquantum limit. We report the first cooldown of a bulk sapphire sample below\nsuperfluid liquid helium temperature (1.6K) to as low as 25mK. The\nelectromagnetic properties were characterised at microwave frequencies, and we\nreport the first observation of electromagnetically induced thermal bistability\nin whispering gallery modes due to the material $T^3$ dependence on thermal\nconductivity and the ultra-low dielectric loss tangent. We identify \"magic\ntemperatures\" between 80 to 2100 mK, the lowest ever measured, at which the\nonset of bistability is suppressed and the frequency-temperature dependence is\nannulled. These phenomena at low temperatures make sapphire suitable for\nquantum metrology and ultra-stable clock applications, including the possible\nrealization of the first quantum limited sapphire clock."
    },
    {
        "anchor": "Ab Initio Many-Body Perturbation Theory Calculations of the Electronic\n  and Optical Properties of Cyclometalated Ir(III) Complexes: Cyclometalled Ir(III) compounds are the preferred choice as organic emitters\nin Organic Light Emitting Diodes. In practice, the presence of the transition\nmetals surrounded by carefully designed ligands allows the fine tuning of the\nemission frequency as well as a good efficiency of the device. To support the\ndevelopment of new compounds the experimental measurements are generally\ncompared with ab-initio calculation of the absorption and emission spectra. The\nstandard approach for these calculations is TDDFT with hybrid exchange and\ncorrelation functional like the B3LYP. Due to the size of these compounds the\napplication of more complex quantum chemistry approaches can be challenging. In\nthis work we used Many Body Perturbation Theory approaches (in particular the\nGW approximation with the Bethe-Salpeter equation) implemented in gaussian\nbasis sets, to calculate the quasiparticle properties and the adsorption\nspectra of six cyclometalled Ir(III) complexes going behind TDDFT. In the\npresented results we compared standard TDDFT simulation with BSE calculations\nperformed on top on perturbative G 0 W 0 and accounting for eigenvalue self\nconsistency. Moreover, in order to investigate in detail the effect of the DFT\nstarting point, we concentrate on Ir(ppy) 3 performing GW-BSE simulations\nstarting from different DFT exchange and correlation potentials.",
        "positive": "Dynamic Simulation of Structural Phase Transitions in Magnetic Iron: The occurrence of bcc-fcc ($\\alpha$-$\\gamma$) and fcc-bcc ($\\gamma$-$\\delta$)\nphase transitions in magnetic iron stems from the interplay between magnetic\nexcitations and lattice vibrations. However, this fact has never been proven by\na direct dynamic simulation, treating non-collinear magnetic fluctuations and\ndynamics of atoms, and their coupling at a finite temperature. Starting from a\nlarge set of data generated by ab initio simulations, we derive non-collinear\nmagnetic many-body potentials for bcc and fcc iron describing fluctuations in\nthe vicinity of near perfect lattice positions. We then use spin-lattice\ndynamics simulations to evaluate the difference between free energies of bcc\nand fcc phases, assessing their relative stability within a unified dynamic\npicture. We find two intersections between the bcc and fcc free energy curves,\nwhich correspond to $\\alpha$-$\\gamma$ bcc-fcc and $\\gamma$-$\\delta$ fcc-bcc\nphase transitions. The maximum fcc-bcc free energy difference over the\ntemperature interval between the two phase transition points is 2 meV, in\nagreement with other experimental and theoretical estimates."
    },
    {
        "anchor": "Thermoelectric Properties of Nanocomposite Heavy Fermion CeCu6: Samples of heavy fermion compound CeCu6 were prepared by hot-press technique.\nTemperature-dependent (5-300 K) thermoelectric transport properties of the\nsamples were measured. The dimensionless figure-of-merit (ZT) was optimized by\nvarying the hot-pressing temperature. Our measurements of thermal conductivity\nshow that the lowest hot pressing temperature (450 C) produces the lowest\nthermal conductivity. Electrical resistivity increases significantly while the\nSeebeck coefficient decreases with decrease in the hot pressing temperature. As\nthe hot-pressing temperature decreases, electronic contribution to the total\nthermal conductivity decreased more rapidly than the lattice contribution did.\nAs a result, for lower hot-pressing temperature the gain in thermal\nconductivity reduction was offset by the loss in power factor. Our ZT\ncalculations show a broad peak with a maximum value of 0.024 at 60 K for the\nsample hot pressed at 800 C. The pronounced low-temperature ZT peak emphasizes\nthe importance of this heavy fermion system as a potential p-type\nthermoelectric for solid state cooling applications.",
        "positive": "Order-disorder transition in the Cd-Ca cubic approximant: Recent experiments discovered an order-disorder transition occuring at low\ntemperatures in large unit 1/1 cell cubic approximants of the stable Cd-based\nbinary alloy quasicrystals. The transition is related to correlations among\norientational degrees of freedom whose separations are around 12 \\AA. We\nanalyze the interactions between the degrees of freedom using {\\em ab-initio}\ncalculations for Cd-Ca alloys and derive an equivalent antiferromagnetic Ising\nmodel which shows a similar phase transition. However, the calculated\ntransition temperature is higher than observed experimentally, indicating that\nthe actual structure and its order-disorder transition are more complex than\noriginally proposed. A side-benefit of our study is the discovery of a\ncanonical-cell decoration model for the Cd-Ca icosahedral phase."
    },
    {
        "anchor": "Room-temperature nanoseconds spin relaxation in WTe2 and MoTe2 thin\n  films: The Weyl semimetal WTe2 and MoTe2 show great potential in generating large\nspin currents since they possess topologically-protected spin-polarized states\nand can carry a very large current density. In addition, the intrinsic\nnoncentrosymmetry of WTe2 and MoTe2 endows with a unique property of crystal\nsymmetry-controlled spin-orbit torques. An important question to be answered\nfor developing spintronic devices is how spins relax in WTe2 and MoTe2. Here,\nwe report a room-temperature spin relaxation time of 1.2 ns (0.4 ns) in WTe2\n(MoTe2) thin film using the time-resolved Kerr rotation (TRKR). Based on ab\ninitio calculation, we identify a mechanism of long-lived spin polarization\nresulting from a large spin splitting around the bottom of the conduction band,\nlow electron-hole recombination rate and suppression of backscattering required\nby time-reversal and lattice symmetry operation. In addition, we find the spin\npolarization is firmly pinned along the strong internal out-of-plane magnetic\nfield induced by large spin splitting. Our work provides an insight into the\nphysical origin of long-lived spin polarization in Weyl semimetals which could\nbe useful to manipulate spins for a long time at room temperature.",
        "positive": "Edge waves and localisation in lattices containing tilted resonators: The paper presents the study of waves in a structured geometrically chiral\nsolid. A special attention is given to the analysis of the Bloch-Floquet waves\nin a doubly periodic high-contrast lattice containing tilted resonators.\nDirac-like dispersion of Bloch waves in the structure is identified, studied\nand applied to wave-guiding and wave-defect interaction problems. The work is\nextended to the transmission problems and models of fracture, where\nlocalisation and edge waves occur. The theoretical derivations are accompanied\nwith numerical simulations and illustrations."
    },
    {
        "anchor": "Nitrogen overgrowth as a catalytic mechanism during diamond chemical\n  vapour deposition: Nitrogen is frequently included in chemical vapour deposition feed gases to\naccelerate diamond growth. While there is no consensus for an atomistic\nmechanism of this effect, existing studies have largely focused on the role of\nsub-surface nitrogen and nitrogen-based adsorbates. In this work, we\ndemonstrate the catalytic effect of surface-embedded nitrogen in nucleating new\nlayers of (100) diamond. To do so we develop a model of nitrogen overgrowth\nusing density functional theory. Nucleation of new layers occurs through C\ninsertion into a C--C surface dimer. However, we find that C insertion into a\nC--N dimer has substantially reduced energy requirements. In particular, the\nrate of the key dimer ring-opening and closing mechanism is increased 400-fold\nin the presence of nitrogen. Full incorporation of the substitutional nitrogen\ndefect is then facilitated through charge transfer of an electron from the\nnitrogen lone pair to charge acceptors on the surface. This work provides a\ncompelling mechanism for the role of surface-embedded nitrogen in enhancing\n(100) diamond growth through the nucleation of new layers. Furthermore, it\ndemonstrates a pathway for substitutional nitrogen formation during chemical\nvapour deposition which can be extended to study the creation of\ntechnologically relevant nitrogen-based defects.",
        "positive": "Observation of Fermi arc spin texture in TaAs: We have investigated the spin texture of surface Fermi arcs in the recently\ndiscovered Weyl semimetal TaAs using spin- and angle-resolved photoemission\nspectroscopy. The experimental results demonstrate that the Fermi arcs are\nspin-polarized. The measured spin texture fulfills the requirement of mirror\nand time reversal symmetries and is well reproduced by our first-principles\ncalculations, which gives strong evidence for the topologically nontrivial Weyl\nsemimetal state in TaAs. The consistency between the experimental and\ncalculated results further confirms the distribution of chirality of the Weyl\nnodes determined by first-principles calculations."
    },
    {
        "anchor": "Current-Density Functional Theory of the Response of Solids: The response of an extended periodic system to a homogeneous field (of\nwave-vector $q=0$) cannot be obtained from a $q=0$ time-dependent density\nfunctional theory (TDDFT) calculation, because the\n  Runge-Gross theorem does not apply. Time-dependent {\\em current}-density\nfunctional theory is needed and demonstrates that one key ingredient missing\nfrom TDDFT is the macroscopic current. In the low-frequency limit, in certain\ncases, density polarization functional theory is recovered and a formally exact\nexpression for the polarization functional is given.",
        "positive": "Suppression of Spin Pumping at Metal Interfaces: An electrically conductive metal typically transmits or absorbs a spin\ncurrent. Here, we report on evidence that interfacing two metal thin films can\nsuppress spin transmission and absorption. We examine spin pumping in\nferromagnet/spacer/ferromagnet heterostructures, in which the spacer --\nconsisting of metallic Cu and Cr thin films -- separates the ferromagnetic\nspin-source and spin-sink layers. The Cu/Cr spacer largely suppresses spin\npumping -- i.e., neither transmitting nor absorbing a significant amount of\nspin current -- even though Cu or Cr alone transmits a sizable spin current.\nThe antiferromagnetism of Cr is not essential for the suppression of spin\npumping, as we observe similar suppression with Cu/V spacers where V is a\nnonmagnetic analogue of Cr. We speculate that diverse combinations of\nspin-transparent metals may form interfaces that suppress spin pumping,\nalthough the underlying mechanism remains unclear. Our work may stimulate a new\nperspective on understanding and engineering spin transport in metallic\nmultilayers."
    },
    {
        "anchor": "Fitting of structural parameters to small angle neutron scattering data\n  for nickel-chromium-aluminum alloy in frames of quantum mechanics and classic\n  models of polydispersed spheres: Modified Yukawa's potential is used to fit model parameters of nucleus to the\nsmall angle thermal neutron scattering data on the nickel-chromium-aluminum\nalloy at the transferred momentum $Q$ and effective nucleus radius $R$\nproduction satisfied by condition $Q R \\le \\hbar$. Analytical polydisperse\nsphere model is used to calculate a neutron scattering intensity and to\ndetermine most probable macroscopic sphere radius $R_0$ at $Q R_0 \\ge 3\\hbar$.\nCombination of gauss, Relay and Schulze-Zimm distributions can be used to fit\nmodel parameters to experimental data. Fast algorithm and program of fitting to\ndata is proposed.",
        "positive": "Effect of local environment on crossluminescence kinetics in SrF2:Ba and\n  CaF2:Ba solid solutions: Spectral and kinetic properties of extrinsic crossluminescence (CL) in\nSrF2:Ba(1%) and CaF2:Ba(1%) are compared with those of intrinsic CL in BaF2 and\nare analyzed taking into account EXAFS data obtained at the Ba LIII edge and\nresults of first-principles calculations. The CL decay time was revealed to be\nlonger in SrF2:Ba and CaF2:Ba compared to BaF2. This fact contradicts the\nexpected acceleration of luminescence decay which could result from an\nincreased overlap of wave functions in solid solutions due to shortening of the\nBa-F distance obtained in both EXAFS measurements and first-principles\ncalculations. This discrepancy is explained by the effect of migration and\nsubsequent non-radiative decay of the Ba(5p) core holes in BaF2 and by\ndecreasing of the probability of optical transitions between Ba(5p) states and\nthe valence band in SrF2:Ba and CaF2:Ba predicted by first-principles\ncalculations."
    },
    {
        "anchor": "Molecular dynamics simulation of UO2 nanocrystals melting under isolated\n  and periodic boundary conditions: Melting of uranium dioxide (UO2) nanocrystals has been studied by molecular\ndynamics (MD) simulation. Ten recent and widely used sets of pair potentials\nwere assessed in the rigid ion approximation. Both isolated (in vacuum) and\nperiodic boundary conditions (PBC) were explored. Using barostat under PBC the\npressure dependences of melting point were obtained. These curves intersected\nzero near -20 GPa, saturated near 25 GPa and increased nonlinearly in between.\nUsing simulation of surface under isolated boundary conditions (IBC)\nrecommended melting temperature and density jump were successfully reproduced.\nHowever, the heat of fusion is still underestimated. These melting\ncharacteristics were calculated for nanocrystals of cubic shape in the range of\n768-49 152 particles (volume range of 10-1000 nm^3). The obtained reciprocal\nsize dependences decreased nonlinearly. Linear and parabolic extrapolations to\nmacroscopic values are considered. The parabolic one is found to be better\nsuited for analysis of the data on temperature and heat of melting.",
        "positive": "Electrical Control of Large Rashba Effect in Oxide Heterostructures: Large Rashba effect efficiently tuned by an external electric field is highly\ndesired for spintronic devices. Using first-principles calculations, we\ndemonstrate that large Rashba splitting is locked at conduction band minimum in\nferroelectric Bi(Sc/Y/La/Al/Ga/In)O3/PbTiO3 heterostructures where the position\nof Fermi level is precisely controlled via its stoichiometry. Fully reversible\nRashba spin texture and drastic change of Rashba splitting strength with\nferroelectric polarization switching are realized in the symmetric and\nasymmetric heterostructures, respectively. By artificially tuning the local\nferroelectric displacement and the orbital hybridization, the synergetic effect\nof local potential gradient and orbital overlap on the dramatic change of\nsplitting strength is confirmed. These results improve the feasibility of\nutilizing Rashba spin-orbit coupling in spintronic devices."
    },
    {
        "anchor": "Spin-orbit-torque magnetization switching of a three terminal\n  perpendicular magnetic tunnel junction: We report on the current-induced magnetization switching of a three-terminal\nperpendicular magnetic tunnel junction by spin-orbit torque and the read-out\nusing the tunnelling magnetoresistance (TMR) effect. The device is composed of\na perpendicular Ta/FeCoB/MgO/FeCoB stack on top of a Ta current line. The\nmagnetization of the bottom FeCoB layer can be switched reproducibly by the\ninjection of current pulses with density $5\\times10^{11}$ A/m$^2$ in the Ta\nlayer in the presence of an in-plane bias magnetic field, leading to the\nfull-scale change of the TMR signal. Our work demonstrates the proof of concept\nof a perpendicular spin-orbit torque magnetic memory cell.",
        "positive": "Multicaloric effects in Metamagnetic Heusler Ni-Mn-In under uniaxial\n  stress and magnetic field: The world's growing hunger for artificial cold on the one hand, and the ever\nmore stringent climate targets on the other, pose an enormous challenge to\nmankind. Novel, efficient and environmentally friendly refrigeration\ntechnologies based on solid-state refrigerants can offer a way out of the\nproblems arising from climate-damaging substances used in conventional\nvapor-compressors. Multicaloric materials stand out because of their large\ntemperature changes which can be induced by the application of different\nexternal stimuli such as a magnetic, electric, or a mechanical field. Despite\nthe high potential for applications and the interesting physics of this group\nof materials, only few studies focus on their investigation by direct methods.\nIn this paper, we report on the advanced characterization of all relevant\nphysical quantities that determine the multicaloric effect of a Ni-Mn-In\nHeusler compound. We have used a purpose-designed calorimeter to determine the\nisothermal entropy and adiabatic temperature changes resulting from the\ncombined action of magnetic field and uniaxial stress on this metamagnetic\nshape-memory alloy. From these results, we can conclude that the multicaloric\nresponse of this alloy by appropriate changes of uniaxial stress and magnetic\nfield largely outperforms the caloric response of the alloy when subjected to\nonly a single stimulus. We anticipate that our findings can be applied to other\nmulticaloric materials, thus inspiring the development of refrigeration devices\nbased on the multicaloric effect."
    },
    {
        "anchor": "Directional Phonon Suppression Function as a Tool for the Identification\n  of Ultralow Thermal Conductivity Materials: Boundary-engineering in nanostructures has the potential to dramatically\nimpact the development of materials for high-efficiency conversion of thermal\nenergy directly into electricity. In particular, nanostructuring of\nsemiconductors can lead to strong suppression of heat transport with little\ndegradation of electrical conductivity. Although this combination of material\nproperties is promising for thermoelectric materials, it remains largely\nunexplored. In this work, we introduce a novel concept, the directional phonon\nsuppression function, to unravel boundary-dominated heat transport in\nunprecedented detail. Using a combination of density functional theory and the\nBoltzmann transport equation, we compute this quantity for nanoporous silicon\nmaterials. We first compute the thermal conductivity for the case with aligned\ncircular pores, confirming a significant thermal transport degradation with\nrespect to the bulk. Then, by analyzing the information on the directionality\nof phonon suppression in this system, we identify a new structure of\nrectangular pores with the same porosity that enables a four-fold decrease in\nthermal transport with respect to the circular pores. Our results illustrate\nthe utility of the directional phonon suppression function, enabling new\navenues for systematic thermal conductivity minimization and potentially\naccelerating the engineering of next-generation thermoelectric devices.",
        "positive": "Direct observation of Landau level resonance and mass generation in\n  Dirac semimetal Cd3As2 thin films: Three-dimensional topological Dirac semimetals have hitherto stimulated\nunprecedented research interests as a new class of quantum materials. Breaking\ncertain types of symmetries has been proposed to enable the manipulation of\nDirac fermions; and that was soon realized by external modulations such as\nmagnetic fields. However, an intrinsic manipulation of Dirac states, which is\nmore efficient and desirable, remains a significant challenge. Here, we report\na systematic study of quasi-particle dynamics and band evolution in Cd3As2 thin\nfilms with controlled Chromium (Cr) doping by both magneto-infrared\nspectroscopy and electrical transport. For the first time, we observe\nsquare-root-B relation of inter-Landau-level resonance in undoped Cd3As2 Dirac\nsemimetal, an important signature of ultra-relativistic Dirac state\ninaccessible in previous optical experiments. A crossover from quantum to\nquasi-classical behavior makes it possible to directly probe the mass of Dirac\nfermions. Importantly, Cr doping allows for a Dirac mass acquisition and\ntopological phase transition enabling a desired dynamic control of Dirac\nfermions. Corroborating with the density-functional theory calculations, we\nshow that the mass generation is essentially driven by explicit C4 rotation\nsymmetry breaking and the resultant Dirac gap engineering through Cr\nsubstitution for Cd atoms. The manipulation of the system symmetry and Dirac\nmass in Cd3As2 thin films provides a tuning knob to explore the exotic states\nstemming from the parent phase of Dirac semimetals."
    },
    {
        "anchor": "Ab initio Study of Valley Line on a Total-Energy Surface for Zone-Center\n  Distortions of Ferroelectric Perovskite Oxides BaTiO3 and PbTiO3: An ab initio structure optimization technique is newly developed to determine\nthe valley line on a total-energy surface for zone-center distortions of\nferroelectric perovskite oxides and is applied to barium titanate BaTiO3 and\nlead titanate PbTiO3. The proposed technique is an improvement over King-Smith\nand Vanderbilt's scheme [Phys. Rev. B 49, p.5828 (1994)] of evaluating total\nenergy as a function of the amplitude of atomic displacements. The results of\nnumerical calculations show that total energy can be expressed as a\nfourth-order function of the amplitude of atomic displacements in BaTiO3 but\nnot in PbTiO3.",
        "positive": "Synthesis of La0.5Ca0.5-x xMnO3 nanocrystalline manganites by sucrose\n  assisted auto combustion route and study of their structural, magnetic and\n  magnetocaloric properties: Perovskite manganite La0.5Ca0.5-x xMnO3 (LCMO) nanomaterials were elaborated\nusing the sucrose modified auto combustion method. Rietveld refinements of the\nX-ray diffraction patterns of the crystalline structure confirm a single-phase\northorhombic state with Pbnm space group (No. 62). The Ca-vacancies were\nvoluntarily created in the LCMO structure in order to study their influence on\nthe magnetic behaviour in the system. The magnetic susceptibility was found to\nbe highly enhanced in the sample with Ca-vacancies.\nParamagnetic-to-ferromagnetic phase transition was evidenced in both samples\naround 254 K. This transition is, characterized by a drastic jump of the\nsusceptibility in the sample with Ca-vacancies. The maximum of entropy change,\nobserved for both compounds at magnetic field of 6T was 2.30 J kg-1K-1 and 2.70\nJ kg-1K-1 for the parent compound and the lacunar one respectively. The\nmagnetocaloric adiabatic temperature change value calculated by indirect method\nwas 5.6 K and 5.2 K for the non-lacunar and Ca-vacancy compound, respectively.\nThe Ca-lacunar La0.5Ca0.5-x xMnO3 (x=0.05) reported in this work demonstrated\noverall enhancement of the magnetocaloric effect over the LCMO. The technique\nused to elaborate LCMO materials was beneficial to enhance the magnetocaloric\neffect and magnetic behaviour. Therefore, we conclude that this less costly\nenvironmentally friendly system can be considered as more advantageous\ncandidate for magnetic refrigeration applications then the commonly Gd-based\ncompounds."
    },
    {
        "anchor": "Relating melting trends and elasticity in simple metals: an empirical\n  potential approach: We demonstrate that the melting points and other thermodynamic quantities of\nthe alkali metals can be calculated based on static crystalline properties. To\ndo this we derive analytic interatomic potentials for the alkali metals fitted\nprecisely to cohesive and vacancy energies, elastic moduli, lattice parameter\nand crystal stability. These potentials are then used to calculate melting\npoints by simulating the equilibration of solid and liquid samples in thermal\ncontact at ambient pressure. With the exception of lithium, remarkably good\nagreement is found with experimental values. The instability of the bcc\nstructure in Li and Na at low temperatures is also reproduced, and, unusually,\nis not due to a soft T1N phonon mode. No forces or finite temperature\nproperties are included in the fit, so this demonstrates a surprisingly high\nlevel of intrinsic transferrability in the simple potentials. Currently, there\nare few potentials available for the alkali metals, so in, addition to\ndemonstrating trends in behaviour, we expect that the potentials will be of\nbroad general use.",
        "positive": "Efficient Green Emission from Edge States in Graphene Perforated by\n  Nitrogen Plasma Treatment: Plasma functionalization of graphene is one of the facile ways to tune its\ndoping level without the need for wet chemicals making graphene\nphotoluminescent. Microscopic corrugations in the two-dimensional structure of\nbilayer CVD graphene having a quasi-free-suspended top layer, such as graphene\nripples, nanodomes, and bubbles, may significantly enhance local reactivity\nleading to etching effects on exposure to plasma. Here, we discovered that\nbilayer CVD graphene treated with nitrogen plasma exhibits efficient\nUV-green-red emission, where the excitation at 250 nm leads to\nphotoluminescence with the peaks at 390, 470, and 620 nm, respectively. By\nusing Raman scattering and spectroscopic ellipsometry, we investigated doping\neffects induced by oxygen or nitrogen plasma on the optical properties of\nsingle- and bilayer CVD graphene. The surface morphology of the samples was\nstudied by atomic force microscopy. It is revealed that the top sheet of\nbilayer graphene becomes perforated after the treatment by nitrogen plasma. Our\ncomprehensive study indicates that the dominant green emission is associated\nwith the edge defect structure of perforated graphene filled with nitrogen. The\ndiscovered efficient emission appearing in nitrogen plasma treated perforated\ngraphene may have a significant potential for the development of advanced\noptoelectronic materials."
    },
    {
        "anchor": "Structural and electronic properties of V2O5 and their tuning by doping\n  with 3d elements - Modelling with DFT+U method and dispersion correction: New electrode materials for alkaline-ion batteries are a timely topic. Among\nmany promising candidates, V2O5 is one of the most interesting cathode\nmaterials. While having very high theoretical capacity, in practice, its\nperformance is hindered by low stability and poor conductivity. As regards\ntheoretical descriptions of V2O5, common DFT-GGA calculations fail to reproduce\nboth the electronic and crystal structure. While the band gap is\nunderestimated, the interlayer spacing is overestimated as weak dispersion\ninteractions are not properly described within GGA. Here we show that the\ncombination of the DFT+U method and semi-empirical D2 correction can compensate\nfor the drawbacks of the GGA approximation when it comes to the modelling of\nV2O5. When compared to common PBE calculations, with a modest increase of the\ncomputational cost, PBE+U+D2 fully reproduced the experimental band gap of\nV2O5, while the errors in the lattice parameters are only a few percent. Using\nthe proposed PBE+U+D2 methodology we studied V2O5 doped with 3d elements (from\nSc to Zn). We show that both the structural and electronic parameters are\naffected by doping. Most importantly, a significant increase of conductivity is\nexpected upon doping, which is of great importance for the application of V2O5\nin metal-ion batteries.",
        "positive": "Theoretical study of ternary silver fluorides AgMF4 (M = Co, Ni, Cu)\n  formation at pressures up to 20 GPa: Only several compounds bearing Ag(II) cation and other transition metal\ncation have been known. Herein, we predict stability and crystal structures of\nhypothetical ternary silver(II) fluorides with copper, nickel and cobalt in 1:1\nstoichiometry at pressure range from 0 GPa up to 20 GPa within the frame of\nDensity Functional Theory. Calculations show that AgCoF4 could be synthesized\nalready at ambient conditions but this compound would host diamagnetic Ag(I)\nand high-spin Co(III). However, at increased pressure ternary fluorides of\nAg(II) featuring Cu and Ni could be synthesized, in the pressure windows of\n7-14 and 8-15 GPa, respectively. All title compounds would be semiconducting\nand magnetically ordered."
    },
    {
        "anchor": "Full characterization and modelling of graded interfaces in a high\n  lattice-mismatch axial nanowire heterostructure: Controlling the strain level in nanowire heterostructures is critical for\nobtaining coherent interfaces of high crystalline quality and for the setting\nof functional properties such as photon emission, carrier mobility or\npiezoelectricity. In a nanowire axial heterostructure featuring a sharp\ninterface, strain is set by the materials lattice mismatch and the nanowire\nradius. Here, we show that introducing a graded interface in nanowire\nheterostructures offers an additional parameter to control strain. For a given\ninterface length and lattice mismatch, we first derive theoretically the\nmaximum nanowire radius below which coherent growth is possible. We validate\nthese findings by growing and characterizing various In(Ga)As/GaAs nanowire\nheterostructures with graded interfaces. Furthermore, we perform a complete\nchemical and structural characterization of the interface by combining\nenergy-dispersive X-ray spectroscopy and high resolution transmission electron\nmicroscopy. In the case of coherent growth, we directly observe that the\nmismatch strain relaxes elastically on the side walls of the nanowire around\nthe interface area, while the core of the nanowire remains partially strained.\nMoreover, our experimental data show good agreement with finite element\ncalculations. This analysis confirms in particular that mechanical strain is\nlargely reduced by interface grading. Overall, our work extends the parameter\nspace for the design of nanowire heterostructures, thus opening new\nopportunities for nanowire optoelectronics.",
        "positive": "Development of radioactive beams at ALTO: Part 1. Physicochemical\n  comparison of different types of UCx targets using a multivariate statistical\n  approach: The optimization of the microstructure of the UCx target is a key point since\nmany years in the field of ISOL method. The ultimate goal is to facilitate the\nrelease of the fission products, especially those with short half-lives.\nFourteen UCx samples were synthetized from different uranium and carbon sources\nusing three mixing protocols. All carburized samples were systematically\ncharacterized in terms of nature and proportion phases, grain and aggregate\nsize, open and close porosity proportion and open pore size distribution. Our\nresults were analysed using a multivariate statistical approach in order to\nremove any subjective bias. Strong correlations between the physicochemical\ncharacteristics of the samples as well as the impact of the synthesis process\nhave been highlighted. In particular, using carbon nanotubes as carbon source\ncombined with a new method of mixing is the key parameter to limit the\nsintering and to obtain samples with small grains and a high porosity well\ndistributed over small pores. Moreover the microstructure obtained proved to be\nstable at high temperature."
    },
    {
        "anchor": "Carbon dimer defect as a source of the 4.1 eV luminescence in hexagonal\n  boron nitride: We propose that the carbon dimer defect in hexagonal boron nitride gives rise\nto the ubiquitous narrow luminescence band with a zero-phonon line of 4.08 eV\n(usually labeled the 4.1 eV band). Our first-principles calculations are based\non hybrid density functionals that provide a reliable description of wide\nband-gap materials. The calculated zero-phonon line energy of 4.3 eV is close\nto the experimental value, and the deduced Huang-Rhys factor of ${S \\approx\n2.0}$, indicating modest electron-phonon coupling, falls within the\nexperimental range. The optical transition occurs between two localized\n$\\pi$-type defects states, with a very short radiative lifetime of 1.2\nnanoseconds, in very good accord with experiments.",
        "positive": "Depth evolution of YBa2Cu3O7-d ultrathin films probed by X-ray\n  photoemission spectroscopy: X-ray photoemission spectroscopy has been used to investigate the depth\ndependent crystal structures and chemical compositions of sequentially\nchemical-etched YBa2Cu3O7-d (YBCO) ultrathin film superconductors. In the\nnear-interface region the crystal structure is severely oxygen deficient and of\ntetragonal symmetry. We consider this a revelation of retarded oxygen diffusion\ninto the O(1) sites during the post-deposition annealing in the presence of\ninterface mismatch strain. Near the free surface, the oxygen-deficiency was\nmuch alleviated because of the partial strain relaxation and the crystal\nsymmetry becomes orthorhombic. Compared with as-deposited films of equivalent\nthickness, which is less oxygen deficient and shows superconducting transition,\nthe stripped-down near-interface layer exhibits no sign of superconductivity."
    },
    {
        "anchor": "A Rigorous Method of Calculating Exfoliation Energies from First\n  Principles: The exfoliation energy, the energy required to peel off an atomic layer from\nthe surface of a bulk material, is of fundamental importance in the science and\nengineering of two-dimensional materials. Traditionally, the exfoliation energy\nof a material has been obtained from first principles by calculating the\ndifference in the ground-state energy between (i) a slab of $N$ atomic layers\n($N \\gg 1$) and (ii) a slab of $N-1$ atomic layers plus an atomic layer\nseparated from the slab. In this paper, we prove that the exfoliation energy\ncan be obtained exactly as the difference in the ground-state energy between a\nbulk material (per atomic layer) and a single isolated layer. The proposed\nmethod is (i) tremendously lower in computational cost than the traditional\napproach since it does not require calculations on thick slabs, (ii) still\nvalid even if there is a surface reconstruction of any kind, (iii) capable of\ntaking into account the relaxation of the single exfoliated layer (both\nin-plane lattice parameters and atomic positions), and (iv) easily combined\nwith all kinds of many-body computational methods. As a proof of principles, we\ncalculated exfoliation energies of graphene, hexagonal boron nitride, MoS$_2$\nand phosphorene using density-functional theory. In addition, we found that the\nin-plane relaxation of an exfoliated layer accounts for 5% of one-layer\nexfoliation energy of phosphorene while it is negligible (< 0.4%) in the other\ncases.",
        "positive": "Unconventional Large Linear Magnetoresistance in Cu$_{2-x}$Te: We report a large linear magnetoresistance in Cu$_{2-x}$Te, reaching\n$\\Delta\\rho/\\rho(0)$ = 250\\% at 2 K in a 9 T field. This is observed for\nsamples with $x$ in the range 0.13 to 0.22, and the results are comparable to\nthe effects observed in Ag$_2 X$ materials, although in this case the results\nappear for a much wider range of bulk carrier density. Examining the magnitude\nvs. crossover field from low-field quadratic to high-field linear behavior, we\nshow that models based on classical transport behavior best explain the\nobserved results. The effects are traced to misdirected currents due to\ntopologically inverted behavior in this system, such that stable surface states\nprovide the high mobility transport channels. The resistivity also crosses over\nto a $T^2$ dependence in the temperature range where the large linear MR\nappears, an indicator of electron-electron interaction effects within the\nsurface states. Thus this is an example of a system in which these interactions\ndominate the low-temperature behavior of the surface states."
    },
    {
        "anchor": "Quantum Flexoelectricity in Low Dimensional Systems: Symmetry breaking at surfaces and interfaces and the capability to support\nlarge strain gradients in nanoscale systems enable new forms of\nelectromechanical coupling. Here we introduce the concept of quantum\nflexoelectricity, a phenomenon that is manifested when the mechanical\ndeformation of non-polar quantum systems results in the emergence of net dipole\nmoments and hence linear electromechanical coupling proportional to local\ncurvature. The concept is illustrated in carbon systems, including\npolyacetylene and nano graphitic ribbons. Using density functional theory\ncalculations for systems made of up to 400 atoms, we determine the\nflexoelectric coefficients to be of the order of ~ 0.1 e, in agreement with the\nprediction of linear theory. The implications of quantum flexoelectricity on\nelectromechanical device applications, and physics of carbon based materials\nare discussed.",
        "positive": "Energy ordering of grain boundaries in Cr2O3: Insights from theory: The grain boundaries, GBs, of corundum Cr2O3 are known to play an important\nrole in the diffusion of ions within the oxide, which is an important\nphenomenon for the corrosion of the stainless steels. The extent of the growth\nof oxide layers in stainless steel depends upon which interfaces are preferred\nwithin Cr2O3. Therefore, we have constructed four different grain boundary\nplanes (rhombohedral, basal, prismatic and pyramidal) and their various\nassociated interface symmetries known in literature for corundum Al2O3. Their\nstructural, electronic, and energetic properties are investigated theoretically\nwith periodic calculations using the DFT+U approach. We find that the prismatic\nscrew GB with a Cr-O plane interface is the energetically preferred GB with the\nrhombohedral GB with screw symmetry and Cr vacancy termination being the second\nenergetically preferred GB. The increase of the number of in-plane Cr atoms at\nthe interface of prismatic GB enhances the stability which is also evident in\nthe electronic density of states."
    },
    {
        "anchor": "d0 Ferromagnetism in Ag-doped Monoclinic ZrO2 Compounds: Recently d0 or intrinsic ferromagnetism was believed to provide an\nalternative pathway to transition metal induced ferromagnetism in oxide. In\npursuit of augmenting the area of d0 ferromagnetism; we have undertaken to\nstudy the crystal structure and magnetic properties of Ag-doped ZrO2 compounds.\nPolycrystalline samples of Zr1-xAgxO2 (with x=0, 0.02, 0.04, 0.06 and 0.08)\nwere prepared by solid-state reaction route. All the prepared compounds are\nfound to crystallize in monoclinic symmetry of ZrO2. In our study, pure ZrO2\ncompound exhibits paramagnetic behavior. However, the Ag-doped ZrO2 compounds\nexhibit ferromagnetic to paramagnetic transition. The Curie temperature was\nfound to increase from 28.7 K for x=0.02 to 173.2 K for x= 0.08 doped ZrO2.\nThus, the introduction of Ag in ZrO2 induces ferromagnetism with a large\nThetaC. The measurements of hysteresis curves indicate that Ag doped ZrO2\ncompounds exhibit hysteresis loops with a coercivity of around 1350 Oe.\nMoreover, increase in Ag concentration resulted increase in the value of\nsaturation magnetization (MS); the maximum value of MS was recorded as 0.01\n{\\mu}B/Ag ion for x= 0.06 sample. The sintering of sample at high temperature\n(13500C) diminishes the ferromagnetism and it leads to paramagnetic behaviour.",
        "positive": "Ferroelectricity in Incommensurate Magnets: We review the phenomenology of coupled magnetic and electric order parameters\nfor systems in which ferroelectric and incommensurate magnetic order occur\nsimultaneously. We discuss the role that such materials might play in\nfabricating novel magnetoelectric devices. Then we briefly review the\nmean-field description of ferroelectricity and modulated magnetic ordering as a\npreliminary to analyzing the symmetry of the interaction between the\nspontaneous polarization and the order parameters describing long-range\nmodulated magnetic ordering. As illustration we show how this formulation\nprovides a phenomenological explanation for the observed phase transitions in\nNi$_3$V$_2$O$_8$ and TbMnO$_3$ in which ferroelectric and magnetic order\nparameters simultaneously become nonzero at a single phase transition. In\naddition, this approach explains the fact that the spontaneous polarization\nonly appears along a specific crystallographic direction. We analyze the\nsymmetry of the strain dependence of the exchange tensor and show that it is\nconsistent with the macroscopic symmetry analysis. We conclude with a brief\ndiscussion of how our approach might be relevant in understanding other systems\nwith coupled magnetic and ferroelectric order, and more importantly, how these\nprinciples relate to the search for materials with larger magnetoelectric\ncouplings at room temperature."
    },
    {
        "anchor": "^{63,65}Cu NMR and NQR evidence for an unusual spin dynamics in PrCu_2\n  below 100 K: We report the results of a $^{63,65}$Cu NMR/NQR study probing the\nintermetallic compound PrCu$_2$. The previously claimed onset of magnetic order\nat 65 K, indicated in a $\\mu$SR study, is not confirmed. Based on our data we\ndiscuss different possible reasons for this apparent discrepancy, including a\nnon negligible influence of the implanted muons on their environment. Competing\ndipolar and quadrupolar interactions lead to unusual features of the\nmagnetic-ion/conduction-electron system, different from those of common\nintermetallics exhibiting structural or magnetic instabilities.",
        "positive": "Vibrational temperature of the adlayer in \"hot atom\" reaction mechanism: Hot-atoms reactions mechanisms bring about reaction rates which are several\norders of magnitude higher than those expected in the case of ad-atoms which\nhave thermalized with the surface. This paper addresses the issue of a possible\nthermodynamic characterization of the adlayer under reactive conditions and at\nthe steady state. In turn, this implies to tackle the question of determining\nthe temperature of the ad-atoms. This is done by means of a nonequilibrium\nstatistical thermodynamic approach, by exploiting a suitable definition of the\nentropy. The interplay between reaction rate, vibrational temperature of the\nad-atoms and adsorbed quantities is highlighted. It is shown that the\nvibrational temperature depends on reaction rate logarithmically and exhibits a\nnon-linear scaling on physical quantities linked to the energetics of the\nreaction, namely the adsorption energy and the binding energy of the molecule.\nThe present modeling is also discussed in connection with response equations of\nnonequilibrium thermodynamics."
    },
    {
        "anchor": "Novel Bismaleimide Resin/Silsesquioxane and Titania Nanocomposites by\n  the Sol-Gel Process: the Preparation, Morphology, Thermal and\n  Thermo-mechanical Properties: Bismaleimide(BMI) resin/silsesquioxane or titania nanocomposites were\nsynthesized from bismaleimide resin and SiO3/2 or TiO2 via the sol-gel process\nof N-{\\gamma}-triethoxylsilylpropyl-maleamic acid (TESPMA) or\ntetrabutyltitanate (Ti(OnBu)4, TBT), respectively, in the presence of the\nAP-BMI prepolymers. These nanocomposite materials were characterized by FT-IR,\nFE-SEM, TGA and DMA. It was found that the nano-scale SiO3/2 or TiO2 particles\nwere formed in the AP-BMI resin matrix and the average original particle size\nof the dispersed phase in the nanocomposites was less than 100nm, but the\nparticle aggregates with bigger size existed. Obvious improvements of Tg and\nthe heat resistance of the AP-BMI resin were achieved by introduction of the\nnano-sized SiO3/2 inorganic phase, and the modulus at high temperatures was\nimproved too. The incorporation of nano-scale TiO2 particles into the AP-BMI\nresin improved the Tg of the polymer, but lowered the thermal resistance of the\nmaterial, and improved the modulus of the material at lower temperatures, but\nlowered the modulus at higher temperatures.",
        "positive": "Ideal Spin Filters: Theoretical Study of Electron Transmission Through\n  Ordered and Disordered Interfaces Between Ferromagnetic Metals and\n  Semiconductors: It is predicted that certain atomically ordered interfaces between some\nferromagnetic metals (F) and semiconductors (S) should act as ideal spin\nfilters that transmit electrons only from the majority spin bands or only from\nthe minority spin bands of the F to the S at the Fermi energy, even for F with\nboth majority and minority bands at the Fermi level. Criteria for determining\nwhich combinations of F, S and interface should be ideal spin filters are\nformulated. The criteria depend only on the bulk band structures of the S and F\nand on the translational symmetries of the S, F and interface. Several examples\nof systems that meet these criteria to a high degree of precision are\nidentified. Disordered interfaces between F and S are also studied and it is\nfound that intermixing between the S and F can result in interfaces with spin\nanti-filtering properties, the transmitted electrons being much less spin\npolarized than those in the ferromagnetic metal at the Fermi energy. A patent\napplication based on this work has been commenced by Simon Fraser University."
    },
    {
        "anchor": "On the search for the chiral anomaly in Weyl semimetals: The negative\n  longitudinal magnetoresistance: Recently, the existence of massless chiral (Weyl) fermions has been\npostulated in a class of semi-metals with a non-trivial energy dispersion.These\nmaterials are now commonly dubbed Weyl semi-metals (WSM).One predicted property\nof Weyl fermions is the chiral or Adler-Bell-Jackiw anomaly, a chirality\nimbalance in the presence of parallel magnetic and electric fields. In WSM, it\nis expected to induce a negative longitudinal magnetoresistance (NMR), the\nchiral magnetic effect.Here, we present experimental evidence that the\nobservation of the chiral magnetic effect can be hindered by an effect called\n\"current jetting\". This effect also leads to a strong apparent NMR, but it is\ncharacterized by a highly non-uniform current distribution inside the sample.\nIt appears in materials possessing a large field-induced anisotropy of the\nresistivity tensor, such as almost compensated high-mobility semimetals due to\nthe orbital effect.In case of a non-homogeneous current injection, the\npotential distribution is strongly distorted in the sample.As a consequence, an\nexperimentally measured potential difference is not proportional to the\nintrinsic resistance.Our results on the MR of the WSM candidate materials NbP,\nNbAs, TaAs, TaP exhibit distinct signatures of an inhomogeneous current\ndistribution, such as a field-induced \"zero resistance' and a strong dependence\nof the `measured resistance\" on the position, shape, and type of the voltage\nand current contacts on the sample. A misalignment between the current and the\nmagnetic-field directions can even induce a \"negative resistance\".\nFinite-element simulations of the potential distribution inside the sample,\nusing typical resistance anisotropies, are in good agreement with the\nexperimental findings. Our study demonstrates that great care must be taken\nbefore interpreting measurements of a NMR as evidence for the chiral anomaly in\nputative Weyl semimetals.",
        "positive": "Hybrid improper dipolar density wave in NaLaCoWO$_6$: Hybrid Improper Ferroelectricity (HIF) allows the generation of an electrical\npolarization in the AA'BB'O$_6$ double perovskite materials thanks to the\ncombination of two non-polar octahedral distortions. Nevertheless, for selected\ncombination of the A/A' cations a non-polar incommensurate phase is observed\nwith average symmetry $C2/m$. Thanks to a detailed crystallographic description\nof the incommensurate phase, based on electron, neutron and x-ray diffraction\ndata, we show that the incommensurate modulation is related to an abrupt change\nof the out-of-phase tilting along the a- and c-axis whereas the tilting along\nthe b-axis remain constant across the structure. By using group theory and\nsymmetry analysis we show that we observe an incommensurate analog of HIF which\ninduces a hybrid improper dipolar density wave in NaLaCoWO$_6$. The dipolar\nordering is due also in this case to a trilinear invariant involving the\ncommensurate and incommensurate octahedra tilting's."
    },
    {
        "anchor": "Ground and Excited Electronic Structures of Electride and Alkalide\n  Units: The Cases of Metal-Tren, -Azacryptand, and -TriPip222 Complexes: A systematic electronic structure analysis was conducted for M(L)$_n$\nmolecular electrides and their corresponding alkalide units M(L)$_n$M' (M/M' =\nNa, K and L = Tren, Azacryptand, TriPip222 and $n$ = 1, 2). All complexes\nbelong to the superalkali category owing to their low ionization potentials.\nThe saturated molecular electrides display M+(L)n-form with a greatly diffused\nquasispherical electron cloud. They were identified as superatoms considering\nthe contours of populating atomic-type molecular orbitals. The observed\nsuperatomic Aufbau order of M(Tren)$_2$ is 1S, 1P, 1D, 1F, 2S, 2P, and 1G and\nit is consistent with those of M(Azacryptand) and M(TriPip222) up to the\nanalyzed 1F level. Their excitation energies decrease gradually moving from\nM(Tren)$_2$ to M(Azacryptand) and to M(TriPip222). The studied alkalide\ncomplexes carry [M(L)$_n$]$^+$M'$^-$ ionic structure and their dissociation\nenergies vary in the sequence of K(L)$_n$@Na > Na(L)$_n$N@a > K(L)$_n$@K >\nNa(L)$_n$@K. Similar to molecular electrides, the anions of alkalide units\noccupy electrons in diffuse Rydberg-like orbitals. In this work, excited states\nof [M(L)$_n$@M']$^{0,+,-}$ and their trends are also analyzed.",
        "positive": "About negative refraction and left handed materials: Here I present an overview of recent studies of the phenomenon of negative\nrefraction and left-handed materials. I will discuss some basic questions\npertinent to the problem. It is pointed out that the current claims of negative\nrefraction and left handed materials are not conclusive. To support our\nconsideration, I will start with the fundamental physics."
    },
    {
        "anchor": "Polytypism and Unexpected Strong Interlayer Coupling of two-Dimensional\n  Layered ReS2: The anisotropic two-dimensional (2D) van der Waals (vdW) layered materials,\nwith both scientific interest and potential application, have one more\ndimension to tune the properties than the isotropic 2D materials. The\ninterlayer vdW coupling determines the properties of 2D multi-layer materials\nby varying stacking orders. As an important representative anisotropic 2D\nmaterials, multilayer rhenium disulfide (ReS2) was expected to be random\nstacking and lack of interlayer coupling. Here, we demonstrate two stable\nstacking orders (aa and a-b) of N layer (NL, N>1) ReS2 from ultralow-frequency\nand high-frequency Raman spectroscopy, photoluminescence spectroscopy and\nfirst-principles density functional theory calculation. Two interlayer shear\nmodes are observed in aa-stacked NL-ReS2 while only one interlayer shear mode\nappears in a-b-stacked NL-ReS2, suggesting anisotropic-like and isotropic-like\nstacking orders in aa- and a-b-stacked NL-ReS2, respectively. The frequency of\nthe interlayer shear and breathing modes reveals unexpected strong interlayer\ncoupling in aa- and a-b-NL-ReS2, the force constants of which are 55-90% to\nthose of multilayer MoS2. The observation of strong interlayer coupling and\npolytypism in multi-layer ReS2 stimulate future studies on the structure,\nelectronic and optical properties of other 2D anisotropic materials.",
        "positive": "Effect of next-nearest neighbor coupling on the optical spectra in\n  bilayer graphene: We investigate the dependence of the optical conductivity of bilayer graphene\n(BLG) on the intra- and inter-layer interactions using the most complete model\nto date. We show that the next nearest-neighbor intralayer coupling introduces\nnew features in the low-energy spectrum that are highly sensitive to sample\ndoping, changing significantly the ``universal'' conductance. Further, its\ninterplay with interlayer couplings leads to an anisotropy in conductance in\nthe ultraviolet range. We propose that experimental measurement of the optical\nconductivity of intrinsic and doped BLG will provide a good benchmark for the\nrelative importance of intra- and inter-layer couplings at different doping\nlevels."
    },
    {
        "anchor": "Reformulating hyperdynamics without a transition state theory dividing\n  surface: Reformulating hyperdynamics without using a transition state theory (TST)\ndividing surface makes it possible to accelerate conventional molecular\ndynamics (MD) simulation using a broader range of bias potentials. A new scheme\nto calculate the boost factor is also introduced that makes the hyperdynamics\nmethod more accurate and efficient. Novel bias potentials using the\nhyper-distance and the potential energy slope and curvature along the direction\nvector from a minimum to a current position can significantly reduce the\ncomputational overhead required. Results simulating an atomic force microscope\n(AFM) system validate the new methodology.",
        "positive": "Observation of Kibble-Zurek behavior near the Lifshitz point in\n  ferroelectrics with incommensurate phase: We have investigated non-equilibrium properties of proper uniaxial\nSn$_2$P$_2$(Se$_x$S$_{1-x}$)$_6$ ferroelectrics with the Type II incommensurate\nphase above Lifshitz point $x_{\\rm LP} \\sim 0.28$. We measured dielectric\nsusceptibility with cooling and heating rate ranging 0.002-0.1~K/min, and\nhigh-resolution ultrasound experiments and hypersound Brillouin scattering. For\nsamples with $x \\geqslant 0.28$ clear anomalies were observed at incommensurate\nsecond order transition ($T_i$) and at first order lock-in transition ($T_c$)\nin the regime of very slow cooling rate, whereas the intermediate IC phase is\nnot observed when the rate is faster then 0.1~K/min. In general, increasing the\ncooling rate leads to smearing the anomaly at $T_c$. We explain this effect in\nterms of Kibble-Zurek model for non-equilibrium second order phase transitions.\nIn the ferroelectrics with strongly nonlinear local potential cooling rate\ndefines concentration of domain walls and their size: domain width decreases\nwhen cooling rate increases. At certain conditions the size of domain is\ncomparable to the incommensurate phase modulation period, which lies in\nmicrometer scale in the vicinity of Lifshitz point and leads to pinning of the\nmodulation period by domain wall."
    },
    {
        "anchor": "Epitaxial Ferroelectric La-doped Hf0.5Zr0.5O2 Thin Films: Doping ferroelectric Hf0.5Zr0.5O2 with La is a promising route to improve\nendurance. However, the beneficial effect of La on the endurance of\npolycrystalline films may be accompanied by degradation of the retention. We\nhave investigated the endurance - retention dilemma in La-doped epitaxial\nfilms. Compared to undoped epitaxial films, large values of polarization are\nobtained in a wider thickness range, whereas the coercive fields are similar,\nand the leakage current is substantially reduced. Compared to polycrystalline\nLa-doped films, epitaxial La-doped films show more fatigue but there is not\nsignificant wake-up effect and endurance-retention dilemma. The persistent\nwake-up effect common to polycrystalline La-doped Hf0.5Zr0.5O2 films, is\nlimited to a few cycles in epitaxial films. Despite fatigue, endurance in\nepitaxial La-doped films is more than 1010 cycles, and this good property is\naccompanied by excellent retention of more than 10 years. These results\ndemonstrate that wake-up effect and endurance-retention dilemma are not\nintrinsic in La-doped Hf0.5Zr0.5O2.",
        "positive": "Dispersive Elastodynamics of 1D Banded Materials and Structures: Design: Within periodic materials and structures, wave scattering and dispersion\noccur across constituent material interfaces leading to a banded frequency\nresponse. In an earlier paper, the elastodynamics of one-dimensional periodic\nmaterials and finite structures comprising these materials were examined with\nan emphasis on their frequency-dependent characteristics. In this work, a novel\ndesign paradigm is presented whereby periodic unit cells are designed for\ndesired frequency band properties, and with appropriate scaling, these cells\nare used as building blocks for forming fully periodic or partially periodic\nstructures with related dynamical characteristics. Through this multiscale\ndispersive design methodology, which is hierarchical and integrated, structures\ncan be devised for effective vibration or shock isolation without needing to\nemploy dissipative damping mechanisms. The speed of energy propagation in a\ndesigned structure can also be dictated through synthesis of the unit cells.\nCase studies are presented to demonstrate the effectiveness of the methodology\nfor several applications. Results are given from sensitivity analyses that\nindicate a high level of robustness to geometric variation."
    },
    {
        "anchor": "HOMO band structure and anisotropic effective hole mass in thin\n  crystalline Pentacene films: The band dispersion of the two highest occupied molecular orbital\n(HOMO)-derived bands in thin crystalline Pentacene films grown on Bi(001) was\ndetermined by photoemission spectroscopy. Compared to first-principles\ncalculations our data show a significantly smaller band width and a much larger\nband separation indicating that the molecular interactions are weaker than\npredicted by theory--a direct contradiction to previous reports by Kakuta et\nal. [Phys. Rev. Lett. 98, 247601 (2007)]. The effective hole mass m* at M-bar\nis found to be anisotropic and larger than theoretically predicted. Comparison\nof m* to field effect mobility measurements shows that the band structure has a\nstrong influence on the mobility even at room temperature where we estimate the\nscattering rate to be tau ~3 fs.",
        "positive": "Ordered arrays of InGaN/GaN dot-in-a-wire nanostructures as single\n  photon emitters: The realization of reliable single photon emitters operating at high\ntemperature and located at predetermined positions still presents a major\nchallenge for the development of solid-state systems for quantum light\napplications. We demonstrate single-photon emission from two-dimensional\nordered arrays of GaN nanowires containing InGaN nano-disks. The structures\nwere fabricated by molecular beam epitaxy on (0001) GaN-on-sapphire templates\npatterned with nanohole masks prepared by colloidal lithography.\nLow-temperature cathodoluminescence measurements reveal the spatial\ndistribution of light emitted from a single nanowire heterostructure. The\nemission originating from the topmost part of the InGaN regions covers the\nblue-to-green spectral range and shows intense and narrow quantum dot-like\nphotoluminescence lines. These lines exhibit an average linear polarization\nratio of 92%. Photon correlation measurements show photon antibunching with a\ng(2)(0) values well below the 0.5 threshold for single photon emission. The\nantibunching rate increases linearly with the optical excitation power,\nextrapolating to the exciton decay rate of ~1 ns-1 at vanishing pump power.\nThis value is comparable with the exciton lifetime measured by time-resolved\nphotoluminescence. Fast and efficient single photon emitters with controlled\nspatial position and strong linear polarization are an important step towards\nhigh-speed on-chip quantum information management."
    },
    {
        "anchor": "Ballistic quantum transport in L-shaped Vertical Halo-Implanted\n  p+-GaSb/InAs n-TFETs: In the present work, we have investigated ballistic quantum transport in\nvertical halo implanted p plus minus GaSb InAs n TFETs. We have investigated\nthe current voltage characteristics, ON current, OFF current leakage,\nsubthreshold swing variation as function of gate length, drain length, gate\nundercut, equivalent oxide thickness, High K and drain thickness. The\nelectrostatic control, I V performances and optimization of device structure\nare carried out for novel L shaped nonlinear geometry n TFETs. In the n TFETs\ndevice p plus minus GaSb InAs heterostructure gives rise to type III broken gap\nband alignment. In this geometry the gate electric field and tunnel junction\ninternal field are oriented in same direction and assist the Band to Band\ntunnelling process. To study the ballistic quantum transport in this L shaped\nnonlinear geometry we used 3 D, full-band atomistic sp3d5s spin orbital coupled\ntight binding method based quantum mechanical simulator which works on the\nbasis of Non Equilibrium Green Function formalism to solve coupled Poisson Schr\n\"odinger equation self consistently for potentials and Local Density of state.",
        "positive": "Improving fretting corrosion resistance of CoCrMo alloy with TiSiN and\n  ZrN coatings for orthopedic applications: Total hip replacement is the most effective treatment for late stage\nosteoarthritis. However, adverse local tissue reactions (ALTRs) associated with\nfretting corrosion have been observed in patients with modular total hip\nimplants. The purpose of this study is to increase the fretting corrosion\nresistance of the CoCrMo alloy and the associated metal ion release by applying\nhard coatings to the surface. Cathodic arc evaporation technique (arc-PVD) was\nused to deposit TiSiN and ZrN hard coatings on to CoCrMo substrates. The\nmorphology, chemical composition, crystal structures and residual stress of the\ncoatings were characterized by scanning electron microscopy, energy dispersive\nx-ray spectroscopy, and X-ray diffractometry. Hardness, elastic modulus, and\nadhesion of the coatings were measured by nano-indentation, nano-scratch test,\nand the Rockwell C test. Fretting corrosion resistance tests of coated and\nuncoated CoCrMo discs against Ti6Al4V spheres were conducted on a four-station\nfretting testing machine in simulated body fluid at 1Hz for 1 million cycles.\nPost-fretting samples were analyzed for morphological changes, volume loss and\nmetal ion release. Our analyses showed better surface finish and lower residual\nstress for ZrN coating, but higher hardness and better scratch resistance for\nTiSiN coating. Fretting results demonstrated substantial improvement in\nfretting corrosion resistance of CoCrMo with both coatings. ZrN and TiSiN\ndecreased fretting volume loss by more than 10 times and 1000 times,\nrespectively. Both coatings showed close to 90% decrease of Co ion release\nduring fretting corrosion tests. Our results suggest that hard coating\ndeposition on CoCrMo alloy can significantly improve its fretting corrosion\nresistance and could thus potentially alleviate ALTRs in metal hip implants."
    },
    {
        "anchor": "A Novel Material for In Situ Construction on Mars: Experiments and\n  Numerical Simulations: A significant step in space exploration during the 21st century will be human\nsettlement on Mars. Instead of transporting all the construction materials from\nEarth to the red planet with incredibly high cost, using Martian soil to\nconstruct a site on Mars is a superior choice. Knowing that Mars has long been\nconsidered a \"sulfur-rich planet\", a new construction material composed of\nsimulated Martian soil and molten sulfur is developed. In addition to the raw\nmaterial availability for producing sulfur concrete and a strength reaching\nsimilar or higher levels of conventional cementitious concrete, fast curing,\nlow temperature sustainability, acid and salt environment resistance, 100%\nrecyclability are appealing superior characteristics of the developed Martian\nConcrete. In this study, different percentages of sulfur are investigated to\nobtain the optimal mixing proportions. Three point bending, unconfined\ncompression and splitting tests were conducted to determine strength\ndevelopment, strength variability, and failure mechanisms. The test results\nshow that the strength of Martian Concrete doubles that of sulfur concrete\nutilizing regular sand. It is also shown that the particle size distribution\nplays an important role in the mixture's final strength. Furthermore, since\nMartian soil is metal rich, sulfates and, potentially, polysulfates are also\nformed during high temperature mixing, which might contribute to the high\nstrength. The optimal mix developed as Martian Concrete has an unconfined\ncompressive strength of above 50 MPa. The formulated Martian Concrete is\nsimulated by the Lattice Discrete Particle Model (LDPM), which exhibits\nexcellent ability in modeling the material response under various loading\nconditions.",
        "positive": "An atomically efficient, highly stable and redox active Ce0.5Tb0.5Ox (3%\n  mol.)/MgO catalyst for total oxidation of methane: Redox and catalytic performance in total methane oxidation of a\nnonostructured ceria-terbia catalyst supported on magnesia is presented and\ncompared to that of a pure ceria catalyst supported on MgO. The investigated\nmaterial, Ce0.5Tb0.5Ox (3% mol.)/MgO, features several remarkable properties: a\nquite low total molar loading of the two lanthanide elements, high\nreducibility, as well as very high oxygen storage capacity al low temperatures\nand higher activity than MgO-supported ceria. In terms of lanthanide atomic\ncontent the catalytic performance of Ce0.5Tb0.5Ox (3% mol.)/MgO largely\nimproves compared to that of bulk type ceria and ceria-magnesia solid\nsolutions. Such a behavior implies proper optimization of the usage of\nlanthanide elements. A second contribution to atomic economy in the catalyst\ndesign relates to the fact that the new formulation demonstrate a stabilyty in\nthe redox and catalytic performance against very high temperature treatments.\nAn investigation on the structure of both the fresh and high-temperature-aged\ncatalyst at the atomic scale by means of complementary aberration corrected\nmicroscopy techniques, reveals the ocuurrence of a variety of exotic,\nlanthanide-containing nanostructures, which span fron isolated, atomically\ndispersed Ln species to nonometer-sized CeTbO2-x patches, extended CeTbO2-x\nbilayers and 2D CeTbO2-x nanoparticles. Nanoanalytical results evidence the\nmixing of the two lanthanides at atomic levels in these nanostructures. The\ncombined effects of nanostructuring, mixing of the lanthanides at the atomic\nlevel, and interaction with the MgO oxide are the roots of the improvement in\nfuntional, redox and catalytic properties of the novel Ce0.5Tb0.5Ox (3%\nmol.)/MgO catalyst."
    },
    {
        "anchor": "Large scale synthesis of 2D graphene oxide by mechanical milling of 3D\n  carbon nanoparticles in air: Graphene oxide (GO) is one of the important functional materials. Large-scale\nsynthesis of it is very challenging. Following a simple cost-effective route,\nlarge-scale GO was produced by mechanical (ball) milling, in air, of carbon\nnanoparticles (CNPs) present in carbon soot in the present study. The thickness\nof the GO layer was seen to decrease with an increase in milling time. Ball\nmilling provided the required energy to acquire the in-plane graphitic order in\nthe CNPs reducing the disorders in it. As the surface area of the layered\nstructure became more and more with the increase in milling time, more and more\noxygen of air got attached to the carbon in graphene leading to the formation\nof GO. An increase in the time of the ball mill up to 5 hours leads to a\nsignificant increase in the content of GO. Thus ball milling can be useful to\nproduce large-scale two-dimensional GO for a short time.",
        "positive": "Multi-field approach in mechanics of structural solids: We overview the basic concepts, models, and methods related to the\nmulti-field continuum theory of solids with complex structures. The multi-field\ntheory is formulated for structural solids by introducing a macrocell\nconsisting of several primitive cells and, accordingly, by increasing the\nnumber of vector fields describing the response of the body to external\nfactors. Using this approach, we obtain several continuum models and explore\ntheir essential properties by comparison with the original structural models.\nStatic and dynamical problems as well as the stability problems for structural\nsolids are considered. We demonstrate that the multi-field approach gives a way\nto obtain families of models that generalize classical ones and are valid not\nonly for long-, but also for short-wavelength deformations of the structural\nsolid. Some examples of application of the multi-field theory and directions\nfor its further development are also discussed."
    },
    {
        "anchor": "Symmetry and polarity of the voltage-controlled magnetic anisotropy\n  studied by the Anomalous Hall effect: The voltage-controlled magnetic anisotropy (VCMA) effect in FeB and FeB/W\nfilms was measured by four independent methods. All measurements are consistent\nand show the same tendency. The coercive field, Hall angle, anisotropy field,\nthe magnetization switching time and retention time linearly decrease when the\ngate voltage increases and they linearly increase when the gate voltage\ndecreases.",
        "positive": "Heterostructures of MXenes and N-doped graphene as highly active\n  bifunctional electrocatalysts: MXenes with versatile chemistry and superior electrical conductivity are\nprevalent candidate materials for energy storage and catalysts. Inspired by\nrecent experiments of hybridizing MXenes with carbon materials, here we\ntheoretically design a series of heterostructures of N-doped graphene supported\nby MXene monolayers as bifunctional electrocatalysts for the oxygen reduction\nreaction (ORR) and hydrogen evolution reaction (HER). Our first-principles\ncalculations show that the graphitic sheet on V2C and Mo2C MXenes are highly\nactive with an ORR overpotential down to 0.36 V and reaction free energies for\nthe HER approaching zero, both with low kinetic barriers. Such outstanding\ncatalytic activities originate from the electronic coupling between the\ngraphitic sheet and the MXene, and can be correlated with the pz band center of\nsurface carbon atoms and the work function of the heterostructures. Our\nfindings screen a novel form of highly active electrocatalysts by taking\nadvantage of the fast charge transfer kinetics and strong interfacial coupling\nof MXenes, and illuminate a universal mechanism for modulating the catalytic\nproperties of two-dimensional hybrid materials."
    },
    {
        "anchor": "Characterization of Semiconducting Materials Using the Van der Pauw\n  Method: Semiconductors are currently an active topic of study due to the endless\nrange of applications in electronic hardware and computer engineering. In this\nexperiment, the material properties (i.e. resistivity $\\rho$, Hall coefficient\n$R_{H}$, and mobility $\\mu$) of a doped GaAs sheet is described by utilizing\nHall Effect and the Van der Pauw method with varying temperature $T$ and\nmagnetic field values $B$. It is determined that the sample is an $n$-type\nsemiconductor using the sign of $R_H$, which is measured to be $R_H = -2.9\n\\times 10^{-12} \\pm 0.1 \\times 10^{-14} ~ \\text{m}^{3} \\text{C}^{-1}$, at $T =\n303 ~\\text{K}$ and $B = 3.3 ~\\text{kGs}$. Furthermore, the rate of change for\nthe slope $R_H$ and $T$ is increasing along $B$ at the rate of $\\Delta k/\n\\Delta B = \\left(3.6 \\pm 0.5 \\right) \\times 10^{-16} ~\\text{m}^3 (\\text{CK}\n\\cdot \\text{kGs})^{-1}$, meaning the charge accumulation caused by the current\nand Lorentz force is quadratic in $B$. It is also discovered that $\\mu$, and\ntherefore the electron drift velocity is reduced proportionally at higher\n$T$-values. This method provides a potential analogue in quantum scales with\nthe Quantum Hall Effect and characterisation of quantum dots.",
        "positive": "AFLOW: An automatic framework for high-throughput materials discovery: Recent advances in computational materials science present novel\nopportunities for structure discovery and optimization, including uncovering of\nunsuspected compounds and metastable structures, electronic structure, surface,\nand nano-particle properties. The practical realization of these opportunities\nrequires systematic generation and classification of the relevant computational\ndata by high-throughput methods. In this paper we present Aflow (Automatic\nFlow), a software framework for high-throughput calculation of crystal\nstructure properties of alloys, intermetallics and inorganic compounds. The\nAflow software is available for the scientific community on the website of the\nmaterials research consortium, aflowlib.org. Its geometric and electronic\nstructure analysis and manipulation tools are additionally available for online\noperation at the same website. The combination of automatic methods and user\nonline interfaces provide a powerful tool for efficient quantum computational\nmaterials discovery and characterization."
    },
    {
        "anchor": "Synthesis and Characterization of a LiFe0.6Mn0.4PO4 Olivine Cathode for\n  Application in a New Lithium Polymer Battery: A LiFe0.6Mn0.4PO4 (LFMP) cathode exploiting the olivine structure is herein\nsynthesized and characterized in terms of structure, morphology, and\nelectrochemical features in a lithium cell. The material shows reversibility of\nthe electrochemical process which evolves at 3.5 and 4 V versus Li+/Li due to\nthe Fe+2/Fe+3 and Mn+2/Mn+3 redox couples, respectively, as determined by\ncyclic voltammetry. The LFMP has a well-defined olivine structure revealed by\nX-ray diffraction, a morphology consisting of submicron particle aggregated\ninto micrometric clusters as indicated by scanning and transmission electron\nmicroscopy, with a carbon weight ratio of about 4% as suggested by\nthermogravimetry. The electrode is used in lithium cells subjected to\ngalvanostatic cycling with a conventional liquid electrolyte, and demonstrates\na maximum capacity of 130 mAh g-1, satisfactory rate capability, excellent\nefficiency, and a stable trend. Therefore, the material is studied in a lithium\nmetal polymer cell exploiting an electrolyte based on polyethylene glycol\ndimethyl ether with a solid configuration. The cell reveals very promising\nfeatures in terms of capacity, efficiency, and retention, and suggests the LFMP\nmaterial as a suitable electrode for polymer batteries characterized by\nincreased energy density and remarkable safety.",
        "positive": "Random sequential adsorption of trimers and hexamers: Adsorption of trimers and hexamers built of identical spheres was studied\nnumerically using the Random Sequential Adsorption (RSA) algorithm. Particles\nwere adsorbed on a two dimensional, flat and homogeneous surface. Numerical\nsimulations allow to establish the maximal random coverage ratio, RSA kinetics\nas well as the Available Surface Function (ASF), which is crucial for\ndetermining kinetics of the adsorption process obtained experimentally.\nAdditionally, the density autocorrelation function was measured. All the\nresults were compared with previous results obtained for spheres, dimers and\ntetramers."
    },
    {
        "anchor": "Two-dimensional TiOx nanostructures on Au(111): a Scanning Tunneling\n  Microscopy and Spectroscopy investigation: We investigated the growth of titanium oxide two-dimensional (2D)\nnanostructures on Au(111), produced by Ti evaporation and post-deposition\noxidation. Scanning tunneling microscopy and spectroscopy (STM and STS) and\nlow-energy electron diffraction (LEED) measurements characterized the\nmorphological, structural and electronic properties of the observed structures.\nFive distinct TiO\\sub{x} phases were identified: the \\emph{honeycomb} and\n\\emph{pinwheel} phases appear as monolayer films wetting the gold surface,\nwhile nanocrystallites of the \\emph{triangular}, \\emph{row} and \\emph{needle}\nphases grow mainly over the honeycomb or pinwheel layers. Density Functional\nTheory (DFT) investigation of the honeycomb structure supports a $(2\\times 2)$\nstructural model based on a Ti-O bilayer having $\\text{Ti}_2\\text{O}_3$\nstoichiometry. The pinwheel phase was observed to evolve, for increasing\ncoverage, from single triangular crystallites to a well-ordered film forming a\n$(4\\sqrt{7}\\times 4\\sqrt{7})R19.1^\\circ$ superstructure, which can be\ninterpreted within a moir\\~A\\c{opyright}-like model. Structural characteristics\nof the other three phases were disclosed from the analysis of high-resolution\nSTM measurements. STS measurements revealed a partial metallization of\nhoneycomb and pinwheel and a semiconducting character of row and triangular\nphases.",
        "positive": "Comparative Dielectric Behavior of PbFe$_{1 / 2}$Ta$_{1 / 2}$O$_{3}$ and\n  NaNbO$_{3}$:Gd Relaxor-Like Crystals: Experimental data obtained for PbFe$_{1 / 2}$Ta$_{1 / 2}$O$_{3}$ (PFT) and\nNaNbO$_{3}$: Gd (NaNbGd) single crystals show a diffused dielectric\npermittivity peak that is inherent to relaxor ferroelectrics. However some\ndeviations from the normal relaxor properties were also observed and are under\ndiscussion. One of the key features of the relaxors is the existence of the\nBurns temperature, at which the polar regions appear. We found out that PFT\nshows this feature but the NaNbGd dielectric behavior is different. We analyse\nthese properties within a phenomenological theory and propose a microscopic\nmodel."
    },
    {
        "anchor": "Essential properties of Li/Li$^+$ graphite intercalation compounds: The essential properties of graphite-based 3D systems are thoroughly\ninvestigated by the first-principles method. Such materials cover a simple\nhexagonal graphite, a Bernal graphite, and the stage-1 to stage-4 Li/Li$^+$\ngraphite intercalation compounds. The delicate calculations and the detailed\nanalyses are done for their optimal stacking configurations, bong lengths,\ninterlayer distances, free electron $\\&$ hole densities, Fermi levels,\ntransferred charges in chemical bondings, atom- or ion-dominated energy bands,\nspatial charge distributions and the significant variations after\nintercalation, Li-/Li$^+$- $\\&$ C-orbital-decomposed DOSs. The above-mentioned\nphysical quantities are sufficient in determining the critical orbital\nhybridizations responsible for the unusual fundamental properties. How to\ndramatically alter the low-lying electronic structures by modulating the\nquest-atom/quest-ion concentration is one of focuses, e.g., the drastic changes\non the Fermi level, band widths, and number of energy bands. The theoretical\npredictions on the stage-n-dependent band structures could be examined by the\nhigh-resolution angle-resolved photoemission spectroscopy (ARPES). Most\nimportant, the low-energy DOSs near the Fermi might provide the reliable data\nfor estimating the free carrier density due to the interlayer atomic\ninteractions or the quest-atom/quest-ion intercalation. The van Hove\nsingularities, which mainly arise from the critical points in\nenergy-wave-vector space, could be directly examined by the experimental\nmeasurements of scanning tunneling spectroscopy (STS). Their features should be\nvery useful in distinguishing the important differences among the stage-$n$\ngraphite intercalation compounds, and the distinct effects due to the atom or\nion decoration.",
        "positive": "The influence of cylindrical inclusions on the stability of a\n  directionally solidified interface: This paper extends the stability calculations carried out for a spherical\nparticle [Eur. Phys. J. B, vol. 37 (2004) or arXiv: cond-mat/0401404] to the\ncase of a cylindrical inclusion."
    },
    {
        "anchor": "Size Effect on the Short Range Order in Amorphous Materials: Drawing inspiration from nature, where some organisms can control the short\nrange order of amorphous minerals, we successfully manipulated the short range\norder of amorphous alumina by surface and size effects. By utilizing the Atomic\nLayer Deposition (ALD) method to grow amorphous nanometrically thin films,\ncombined with state-of-the-art electron energy loss spectroscopy (EELS) and\nX-ray photoelectron spectroscopy (XPS), we showed experimentally that the short\nrange order in such films is strongly influenced by size. This phenomenon is\nequivalent to the well-known size effect on lattice parameters and on the\nrelative stability of different polymorphs in crystalline materials. We also\nshow that the short range order changes while still in the amorphous phase,\nbefore the amorphous to crystalline transformation takes place.",
        "positive": "Phonon line shape in disordered A3C60 (A= K, Rb): We present a calculation of the Hg phonon self-energy for a model of A3C60\n(A= K, Rb). The orientational disorder of the C60 molecules is included, and\nthe lowest order self-energy diagram is considered. The calculations illustrate\nthat due to the violation of momentum conservation by the orientational\ndisorder, Raman scattering can measure the decay of a phonon in an\nelectron-hole pair, allowing the estimate of the electron-phonon coupling from\nsuch experiments. Comparison with experimental line shapes further provides\nsupport for a local correlation of the molecular orientations, with neighboring\nmolecules preferentially having orientations differing by a 90 degree rotation."
    },
    {
        "anchor": "Electronic structure and magnetic properties of the strong-rung spin-1\n  ladder compound Rb$_3$Ni$_2$(NO$_3$)$_7$: Small single crystals of Rb$_3$Ni$_2$(NO$_3$)$_7$ were obtained by\ncrystallization from anhydrous nitric acid solution of rubidium nitrate and\nnickel nitrate hexahydrate. The basic elements of the crystal structure of this\nnew compound are isolated spin-1 two-leg ladders of Ni$^{2+}$-ions connected by\n(NO$_3$)$^-$ groups. The experimental data show the absence of long range\nmagnetic order at T $\\geq 2$~K. LDA+U calculations and the detailed analysis of\nthe experimental data, i.e. of the magnetic susceptibility, the specific heat\nin magnetic fields up to 9~T, the magnetization, and of the high-frequency\nelectron spin resonance data, enable quantitative estimates of the relevant\nparameters of the $S=1$ ladders in Rb$_3$Ni$_2$(NO$_3$)$_7$ . The rung-coupling\n$J_1 = 10.5$~K, the leg-coupling $J_2=1.6$~K, and the uniaxial anisotropy $|A|\n= 179$~GHz are obtained. The scenario of spin liquid quantum ground state is\nfurther corroborated by quantum Monte Carlo simulations of the magnetic\nsusceptibility.",
        "positive": "Intrinsic spin-orbit interactions in flat and curved graphene\n  nanoribbons: Recent theoretical and experimental works on carbon nanotubes and graphene\nsamples have revealed that spin-orbit interactions, though customarily ignored\nin carbon-based materials, are more important and complex than it was thought.\nWe study the intrinsic spin-orbit coupling effects on graphene nanoribbons,\nboth flat and bent. Calculations are performed within the tight-binding model\nwith the inclusion of a four-orbital basis set. Thereby the full symmetry of\nthe honeycomb lattice and the hybridization of $\\sigma$ and $\\pi$ bands are\nconsidered. In addition to the zero-energy $\\pi$-edge states, $\\sigma$-derived\nedge states are found for the three investigated ribbon geometries. The\n$\\sigma$ states are also spin-filtered and localized at the boundaries of the\nribbons. The calculated spin-orbit splittings are larger for the $\\sigma$- than\nfor the $\\pi$-derived edge states. Due to this enhancement, spin-orbit\nsplittings of the $\\sigma$-states reach values of the order of a few Kelvin.\nThese spin-filtered edge states are robust under $\\sigma-\\pi$ hybridization and\ncurvature effects."
    },
    {
        "anchor": "Third Harmonic Generation And Photoluminescence Measurements in Zinc\n  Oxide And Aluminum doped Zinc Oxide Thin Films Grown by Atomic Layer\n  Deposition: Zinc Oxide is a thoroughly studied wide-bandgap semiconductor possessing\nexcellent optical and electronic properties at room temperature. The renewed\ninterest in this material has been generated by doping with various impurities\nin order to further enhance versatile optoelectronic responses for practical\napplications. Specifically, Aluminum-doped Zinc Oxide is an emerging\ntransparent conducting oxide for photovoltaic applications. Here I propose to\nconduct a series of experimental studies on broadband optical nonlinearity as\nwell as photoluminescence from Aluminum doped Zinc Oxide as a function of\nAluminum doping. The results of this study include studies including 1) Bandgap\nmeasurements 2) wavelength-dependent third harmonic generation and 3)\none-photon-induced Photoluminescence. The most notable result is a multifold\nenhanced third-order nonlinear optical response from weakly doped Aluminum\ndoped Zinc Oxide (up to 4%) in comparison with the undoped counterpart. The\nobserved nonlinear optical trend as a function of Aluminum doping is correlated\nto the modification of the corresponding band structure. The Aluminum doping\neffect is extensively investigated in the context of absorption and\nPhotoluminescence.",
        "positive": "Surface waves in granular phononic crystals: The existence of surface elastic waves at a mechanically free surface of\ngranular phononic crystals is studied. The granular phononic crystals are made\nof spherical particles distributed periodically on a simple cubic lattice. It\nis assumed that the particles are interacting by means of normal, shear and\nbending contact rigidities. First, Rayleigh-type surface acoustic waves, where\nthe displacement of the particles takes place in the sagittal plane while the\nparticles possess one rotational and two translational degrees of freedom, are\nanalyzed. Second, shear-horizontal-type waves, where the displacement of the\nparticles is normal to the sagittal plane while the particles possess one\ntranslational and two rotational degrees of freedom are studied. The existence\nof zero-group velocity surface acoustic waves of Rayleigh-type is theoretically\npredicted and interpreted. A comparison with surface waves predicted by the\nCosserat theory is performed, and its limitations are established."
    },
    {
        "anchor": "In situ GaN decomposition analysis by quadrupole mass spectrometry and\n  reflection high-energy electron diffraction: Thermal decomposition of wurtzite (0001)-oriented GaN was analyzed: in\nvacuum, under active N exposure, and during growth by rf-plasma assisted\nmolecular beam epitaxy. The GaN decomposition rate was determined by\nmeasurements of the Ga desorption using in situ quadrupole mass spectrometry,\nwhich showed Arrhenius behavior with an apparent activation energy of 3.1 eV.\nClear signatures of intensity oscillations during reflection high-energy\nelectron diffraction measurements facilitated complementary evaluation of the\ndecomposition rate and highlighted a layer-by-layer decomposition mode in\nvacuum. Exposure to active nitrogen, either under vacuum or during growth under\nN-rich growth conditions, strongly reduced the GaN losses due to GaN\ndecomposition.",
        "positive": "Field-induced giant static dielectric constant in nano-particle\n  aggregates at room temperature: The analogy between magnetism and electricity has long been established by\nMaxwell in the 19th century, in spite of their subtle difference. While\nmagnetic materials display paramagnetism, ferromagnetism, antiferromagnetism,\nand diamagnetism, only paraelectricity, ferroelectricity, and\nantiferrolelectricity have been found in dielectric materials. The missing\n`diaelectricity' may be found if there exists a material that has a\ndc-polarization opposing the electric field or a negative dielectric\nsusceptibility epsilon'-1, with epsilon' being the real part of the relative\ndielectric constant. Both of these properties have been observed in\nnano-particle aggregates under a dc electric bias field at room temperature. A\npossible collective effect in the nano-particle aggregates is proposed to\naccount for the observation. `Diaelectricity' implies overscreening by\npolarization to the external charges. Materials with a negative static epsilon'\nare expected to provide attraction to similar charges and unusual scattering to\nelectromagnetic waves with possible profound implications for high temperature\nsuperconductivity and communication."
    },
    {
        "anchor": "Low-defectiveness exfoliation of MoS2 nanoparticles and their embedment\n  in hybrid light-emitting polymer nanofibers: Molybdenum disulfide (MoS2) has been attracting extraordinary attention for\nits intriguing optical, electronic and mechanical properties. Here we\ndemonstrate hybrid, organic-inorganic light-emitting nanofibers based on MoS2\nnanoparticle dopants obtained through a simple and inexpensive sonication\nprocess in N-methyl-2-pyrrolidone and successfully encapsulated in polymer\nfilaments. Defectiveness is found to be kept low, and stoichiometry preserved,\nby the implemented, gentle exfoliation method that allows the MoS2\nnanoparticles to be produced. So-achieved hybrid fibers are smooth, uniform,\nflawless, and exhibit bright and continuous light emission. Moreover, they show\nsignificant capability of waveguiding self-emitted light along their\nlongitudinal axis. These findings suggest the use of emissive MoS2 fibers\nenabled by gentle exfoliation methods as novel and highly promising optical\nmaterial for building sensing surfaces and as components of photonic circuits.",
        "positive": "A lattice approach to model flow in cracked concrete: This paper presents a lattice approach to model the influence of cracking on\ninviscid flow in concrete. A mechanical lattice model based on a\ndamage-plasticity constitutive model was combined with a new dual lattice of\nconduit elements for flow analysis. The diffusivity of the conduit elements\ndepends on the crack-opening obtained from the mechanical lattice. The coupled\nlattice model was applied to several benchmark tests for aligned and random\nlattices. The results for mechanical loading and flow analysis obtained with\nthe new approach were shown to be independent of the size of lattice elements\nused."
    },
    {
        "anchor": "Evidence for Multiferroic Characteristics in NdCrTiO5: We report NdCrTiO5 to be an unusual multiferroic material with large magnetic\nfield dependent electric polarization. While magneto-electric coupling in this\ntwo magnetic sub-lattice oxide is well established, the purpose of this study\nis to look for spontaneous symmetry breaking at the magnetic transition. The\nconclusions are based on extensive magnetization, dielectric and polarization\nmeasurements around its antiferromagnetic ordering temperature of 18K. Room\ntemperature X-ray diffraction pattern of NdCrTiO5 reveals that the sample is\nsingle phase with an orthorhombic crystal structure that allows linear\nmagneto-electric coupling. DC magnetization measurement shows magnetization\ndownturn at 11K together with a small kink corresponding to the Co+3\nsub-lattice ordering at ~18K. An anomaly in dielectric constant is observed\naround the magnetic ordering temperature that increases substantially with\nincreasing magnetic field. Through detailed pyroelectric current measurements\nat zero magnetic field, particularly as a function of thermal cycling, we\nestablish that NdCrTiO5 is a genuine multiferroic material that is possibly\ndriven by collinear magneto-striction.",
        "positive": "Preferential site occupancy of alloying elements in TiAl-based phases: First principles calculations are used to study the preferential occupation\nof ternary alloying additions into the binary Ti-Al phases, namely\n$\\gamma$-TiAl, $\\alpha_2$-Ti$_3$Al, $\\beta_{\\mathrm{o}}$-TiAl, and B19-TiAl.\nWhile the early transition metals (TMs, group IVB, VB , and VIB elements)\nprefer to substitute for Ti atoms in the $\\gamma$-, $\\alpha_2$-, and\nB19-phases, they preferentially occupy Al sites in the\n$\\beta_{\\mathrm{o}}$-TiAl. Si is in this context an anomaly, as it prefers to\nsit on the Al sublattice for all four phases. B and C are shown to prefer\noctahedral Ti-rich interstitial positions instead of substitutional\nincorporation. The site preference energy is linked with the alloying-induced\nchanges of energy of formation, hence alloying-related (de)stabilisation of the\nphases. We further show that the phase-stabilisation effect of early TMs on\n$\\beta_{\\mathrm{o}}$-phase has a different origin depending on their valency.\nFinally, an extensive comparison of our predictions with available theoretical\nand experimental data (which is, however, limited mostly to the $\\gamma$-phase)\nshows a consistent picture."
    },
    {
        "anchor": "Pattern Evolution Characterizes the Mechanism and Efficiency of CVD\n  Graphene Growth: Growing large-area single-crystal monolayers is the holy grail of graphene\nsynthesis. In this work, the efficiency of graphene growth and the quality of\ntheir continuous films are explored through the time evolution of individual\ndomains and their surface coverage on the substrate. Our phase-field modeling\nresults and experimental characterization clearly demonstrate the critical\nroles of the deposition flux, edge-reaction kinetics and the surface diffusion\nof active carbon sources in modulating the pattern evolution and rate of\ngrowth. The contrast in edge-kinetics-limited and surface-diffusion-limited\nregimes is remarkable, which can be characterized by the evolution of domain\npatterns and considered as an indicator of the growth regime. Common features\nexist in these two regimes, showing that the growth rate scales with time as t2\nin the early stage of growth and is regime-independent, which is explained by\nthe coarsen profiles of carbon concentration for both the compact and dendritic\ndomains. The rate decays rapidly in the final stage of growth due to the\ncompetition between neighboring domains on the limited carbon sources diffusing\non the substrate, which is highly regime-sensitive and extremely low in the\nsurface-diffusion-limited regime with narrow gaps between the domains to be\nfilled. Based on these findings, synthesis strategies to improve the growth\nefficiency and film quality are discussed.",
        "positive": "Ultrahigh thermal conductivity and strength in direct-gap semiconducting\n  graphene-like BC6N: A first-principles and classical investigation: In recent years, graphene-like boron carbide and carbon nitride nanosheets\nhave attracted remarkable attentions, owing to their semiconducting electronic\nnature and outstanding mechanical and heat transport properties. Graphene-like\nBC6N is an experimentally realized layered material and most recently has been\nthe focus of numerous theoretical studies. Interestingly, the most stable form\nof BC6N monolayer remains unexplored and limited information are known\nconcerning its intrinsic physical properties. Herein, on the basis of density\nfunctional theory (DFT) calculations we confirm that the most stable form of\nBC6N nanosheet shows a rectangular unitcell, in accordance with an overlooked\nexperimental finding. We found that BC6N monolayer is a semiconductor with 1.19\neV direct gap and yields anisotropic and excellent absorption of visible light.\nFirst-principles results highlight that BC6N nanosheet exhibits anisotropic and\nultrahigh tensile strength and lattice thermal conductivity, outperforming all\nother fabricated 2D semiconductors. We moreover develop classical molecular\ndynamic models for the evaluation of heat transport and mechanical properties\nof BC6N nanomembranes. The presented results in this work not only shed light\non the most stable configuration of BC6N nanosheet, but also confirm its\noutstandingly appealing electronic, optical, heat conduction and mechanical\nproperties, extremely motivating for further theoretical and experimental\nendeavors."
    },
    {
        "anchor": "Dynamic and structural properties of orthorhombic rare-earth manganites\n  under high pressure: We report a high-pressure study of orthorhombic rare-earth manganites AMnO3\nusing Raman scattering (for A = Pr, Nd, Sm, Eu, Tb and Dy) and synchrotron\nX-ray diffraction (for A = Pr, Sm, Eu, and Dy). In all cases, a structural and\ninsulator-to-metal transition was evidenced, with a critical pressure that\ndepends on the A-cation size. We analyze the compression mechanisms at work in\nthe different manganites via the pressure dependence of the lattice parameters,\nthe shear strain in the a-c plane, and the Raman bands associated with\nout-of-phase MnO6 rotations and in-plane O2 symmetric stretching modes. Our\ndata show a crossover across the rare-earth series between two different kinds\nof behavior. For the smallest A-cations, the compression is nearly isotropic in\nthe ac plane, with presumably only very slight changes of tilt angles and\nJahn-Teller distortion. As the radius of the A-cation increases, the\npressure-induced reduction of Jahn-Teller distortion becomes more pronounced\nand increasingly significant as a compression mechanism, while the\npressure-induced bending of octahedra chains becomes conversely less\npronounced. We finally discuss our results in the light of the notion of\nchemical pressure, and show that the analogy with hydrostatic pressure works\nquite well for manganites with small A-cations but can be misleading with large\nA-cations.",
        "positive": "II-VI Organic-Inorganic Hybrid Nanostructures with Greatly Enhanced\n  Optoelectronic Properties, Perfectly Ordered Structures, and Over 15-Year\n  Shelf Stability: Organic-inorganic hybrids may offer material properties not available from\ntheir inorganic components. However, they are typically less stable and\ndisordered. Long-term stability study of the hybrid materials, over the\nanticipated lifespan of a real-world electronic device, is practically\nnonexistent. Disordering, prevalent in most nanostructure assemblies, is a\nprominent adversary to quantum coherence. A family of perfectly ordered II-VI\nbased hybrid nanostructures has been shown to possess a number of unusual\nproperties and potential applications. Here, using a prototype structure\nZnTe(en)0.5 - a hybrid superlattice, and applying an array of optical,\nstructural, surface, thermal, and electrical characterization techniques in\nconjunction with density-functional theory calculations, we have performed a\ncomprehensive and correlative study of the crystalline quality, structural\ndegradation, electronic, optical, and transport properties on samples from over\n15-years old to the recently synthesized. The findings show that not only do\nthey exhibit an exceptionally high level of crystallinity in both macroscopic\nand microscopic scale, comparable to high-quality binary semiconductors; and\ngreatly enhanced material properties, compared to those of the inorganic\nconstituents; but also, some of them over 15-years old remain as good in\nstructure and property as freshly made ones. This study reveals (1) what level\nof structural perfectness is achievable in a complex organic-inorganic hybrid\nstructure or a man-made superlattice, suggesting a non-traditional strategy to\nmake periodically stacked heterostructures with abrupt interfaces; and (2) how\nthe stability of a hybrid material is affected differently by its intrinsic\nattributes, primarily formation energy, and extrinsic factors, such as surface\nand defects."
    },
    {
        "anchor": "Understanding Cu Incorporation in the $\\mathrm{Cu_{2x}Hg_{2-x}GeTe_4}$\n  Structure using Resonant X-ray Diffraction: The ability to control carrier concentration based on the extent of Cu\nsolubility in the $\\mathrm{Cu_{2x}Hg_{2-x}GeTe_4}$ alloy compound (where 0\n$\\leq$ x $\\leq$ 1) makes $\\mathrm{Cu_{2x}Hg_{2-x}GeTe_4}$ an interesting case\nstudy in the field of thermoelectrics. While Cu clearly plays a role in this\nprocess, it is unknown exactly how Cu incorporates into the\n$\\mathrm{Cu_{2x}Hg_{2-x}GeTe_4}$ crystal structure and how this affects the\ncarrier concentration. In this work, we use a combination of resonant energy\nX-ray diffraction (REXD) experiments and density functional theory (DFT)\ncalculations to elucidate the nature of Cu incorporation into the\n$\\mathrm{Cu_{2x}Hg_{2-x}GeTe_4}$ structure. REXD across the $\\mathrm{Cu_k}$\nedge facilitates the characterization of Cu incorporation in the\n$\\mathrm{Cu_{2x}Hg_{2-x}GeTe_4}$ alloy and enables direct quantification of\nanti-site defects. We find that Cu substitutes for Hg at a 2:1 ratio, wherein\nCu annihilates a vacancy and swaps with a Hg atom. DFT calculations confirm\nthis result and further reveal that the incorporation of Cu occurs\npreferentially on one of the z = 1/4 or z = 3/4 planes before filling the other\nplane. Furthermore, the amount of $\\mathrm{Cu_{Hg}}$ anti-site defects\nquantified by REXD was found to be directly proportional to the experimentally\nmeasured hole concentration, indicating that the $\\mathrm{Cu_{Hg}}$ defects are\nthe driving force for tuning carrier concentration in the\n$\\mathrm{Cu_{2x}Hg_{2-x}GeTe_4}$ alloy. The link uncovered here between crystal\nstructure, or more specifically anti-site defects, and carrier concentration\ncan be extended to similar cation-disordered material systems and will aid the\ndevelopment of improved thermoelectric and other functional materials through\ndefect engineering.",
        "positive": "Imitation of spin density wave order in Cu$_3$Nb$_2$O$_8$: Spin density waves, based on modulated local moments, are usually associated\nwith metallic materials, but have recently been reported in insulators which\ndisplay coupled magnetic and structural order parameters. We discuss one such\nexample, the multiferroic Cu$_3$Nb$_2$O$_8$, which is reported to undergo two\nmagnetic phase transitions, first to a spin density wave phase at $T_N \\approx\n26.5K$, and then to a helicoidal structure coupled to an electric polarization\nbelow $T_2 \\approx 24K$ [R. D. Johnson, et al., Phys. Rev. Lett., 107, 137205\n(2011)] which breaks the crystallographic inversion symmetry. We apply\nspherical polarimetry to confirm the low-temperature magnetic structure, yet\nonly observe a single magnetic phase transition to helicoidal order. We argue\nthat the reported spin density wave originates from a decoupling of the\ncomponents of the magnetic order parameter, as allowed by symmetry and driven\nby thermal fluctuations. This provides a mechanism for the magnetic, but not\nnuclear, structure to break inversion symmetry thereby creating an intermediate\nphase where the structure imitates a spin density wave. As the temperature is\nreduced, this intermediate structure destabilizes the crystal such that a\nstructural chirality is induced, as reflected by the emergence of the electric\npolarization, and the imitation spin density wave relaxes into a generic\nhelicoid. This provides a situation where the magnetic structure breaks\ninversion symmetry while the crystal structure remains centrosymmetric."
    },
    {
        "anchor": "Ferroelastic Dynamics and Strain Compatibility: We derive underdamped evolution equations for the order-parameter (OP)\nstrains of a ferroelastic material undergoing a structural transition, using\nLagrangian variations with Rayleigh dissipation, and a free energy as a\npolynomial expansion in the $N=n+N_{op}$ symmetry-adapted strains. The $N_{op}$\nstrain equations are structurally similar in form to the Lagrange-Rayleigh 1D\nstrain dynamics of Bales and Gooding (BG), with `strain accelerations'\nproportional to a Laplacian acting on a sum of the free energy strain\nderivative and frictional strain force. The tensorial St. Venant's elastic\ncompatibility constraints that forbid defects, are used to determine the n\nnon-order-parameter strains in terms of the OP strains, generating anisotropic\nand long-range OP contributions to the free energy, friction and noise. The\n{\\it same} OP equations are obtained by either varying the displacement vector\ncomponents, or by varying the N strains subject to the $N_c$ compatibility\nconstraints. A Fokker-Planck equation, based on the BG dynamics with noise\nterms, is set up. The BG dynamics corresponds to a set of nonidentical\nnonlinear (strain) oscillators labeled by wavevector $\\vec{k}$, with competing\nshort- and long-range couplings. The oscillators have different `strain-mass'\ndensities $\\rho (k) \\sim 1/k^2$ and dampings $\\sim 1/\\rho (k) \\sim k^2$, so the\nlighter large-k oscillators equilibrate first, corresponding to earlier\nformation of smaller-scale oriented textures. This produces a sequential-scale\nscenario for post-quench nucleation, elastic patterning, and hierarchical\ngrowth. (Continued ...)",
        "positive": "Ab initio metadynamics determination of temperature-dependent\n  free-energy landscape in ultrasmall silver clusters: Ab initio metadynamics enables extracting free-energy landscapes having the\naccuracy of first principles electronic structure methods. We introduce an\ninterface between the PLUMED code that computes free-energy landscapes and\nenhanced-sampling algorithms and the ASE module, which includes several ab\ninitio electronic structure codes. The interface is validated with a\nLennard-Jones cluster free-energy landscape calculation by averaging multiple\nshort metadynamics trajectories. We use this interface and analysis to estimate\nthe free-energy landscape of Ag5 and Ag6 clusters at 10, 100 and 300 K with the\nradius of gyration and coordination number as collective variables, finding at\nmost tens of meV in error. Relative free-energy differences between the planar\nand non-planar isomers of both clusters decrease with temperature, in agreement\nwith previously proposed stabilization of non-planar isomers. Interestingly, we\nfind that Ag6 is the smallest silver cluster where entropic effects at room\ntemperature boost the non planar isomer probability to a competing state. The\nnew ASE-PLUMED interface enables simulating nanosystem electronic properties at\nmore realistic temperature-dependent conditions."
    },
    {
        "anchor": "Universal domain wall dynamics under electric field in Ta/CoFeB/MgO\n  devices with perpendicular anisotropy: Electric field effects in ferromagnetic/oxide dielectric structures provide a\nnew route to control domain wall (DW) dynamics with low power dissipation.\nHowever, electric field effects on DW velocities have only been observed so far\nin the creep regime where DW velocities are low due to strong interactions with\npinning sites. Here, we show gate voltage modulation of DW velocities ranging\nfrom the creep to the flow regime in Ta/Co40Fe40B20/MgO/TiO2 structures with\nperpendicular magnetic anisotropy. We demonstrate a universal description of\nthe role of applied electric fields in the various pinning dependent regimes by\ntaking into account an effective magnetic field being linear with the electric\nfield. In addition, the electric field effect is found to change sign in the\nWalker regime. Our work opens new opportunities for the study and optimization\nof electric field effect at ferromagnetic metal/insulator interfaces.",
        "positive": "An atomistic view of grain boundary diffusion: This paper presents an overview of recent computer simulations of grain\nboundary (GB) diffusion focusing on atomistic understanding of diffusion\nmechanisms. At low temperatures when GB structure is ordered, diffusion is\nmediated by point defects inducing collective jumps of several atoms forming a\nchain. At high temperatures when GB structure becomes highly disordered, the\ndiffusion process can be analyzed by statistical methods developed earlier for\nsupercooled liquids and glasses. Previous atomistic simulations reported in the\nliterature as well as the new simulations presented in this paper reveal a\nclose similarity between diffusion mechanisms in GBs and in supercooled\nliquids. GB diffusion at high temperatures is dominated by collective\ndisplacements of atomic groups (clusters), many of which have one-dimensional\ngeometries similar to strings. The recent progress in this field motivates\nfuture extensions of atomistic simulations to diffusion in alloy GBs,\nparticularly in glass-forming systems."
    },
    {
        "anchor": "Dissociation of O2 at Al(111): The Role of Spin Selection Rules: A most basic and puzzling enigma in surface science is the description of the\ndissociative adsorption of O2 at the (111) surface of Al. Already for the\nsticking curve alone, the disagreement between experiment and results of\nstate-of-the-art first-principles calculations can hardly be more dramatic. In\nthis paper we show that this is caused by hitherto unaccounted spin selection\nrules, which give rise to a highly non-adiabatic behavior in the O2/Al(111)\ninteraction. We also discuss problems caused by the insufficient accuracy of\npresent-day exchange-correlation functionals.",
        "positive": "Structural Stability and Defect-Tolerance of Ionic Spinel Semiconductor\n  for High-Efficiency Solar Cells: The incompatibility between defect-tolerance and structural stability is a\nsevere issue hindering the wide application of high-efficiency solar cells.\nUsually, covalent/polar semiconductors with prototype of Si/CdTe crystals\nexhibit great structural stability owing to their compactly composed\ntetrahedral building blocks, but present extremely poor defect-tolerance due to\nthe similar electronegativity of component elements. On the contrary, ionic\nsemiconductors, such as perovskite series, always exhibit benign electronic\nproperties of intrinsic defects owing to the great disparity of\nelectronegativity between anions and cations, but are structurally unstable\nbecause of the sparsely composed octahedral building blocks supported by large\ncations. Combining the stable framework of covalent semiconductors and benign\ndefects of ionic compounds, we find that HgX2S4 (X=In, Sc and Y) spinel\nsemiconductors possess both the merits. The tightly combined tetrahedral and\noctahedral blocks ensures the structural stability, and the band edge of ionic\ncharacteristic, which is mainly dominated by Hg-6s and S-3p orbitals for\nconduction band minimum (CBM) and valence band maximum (VBM), respectively,\nmakes HgX2S4 defect-tolerant. The prominent downward bending of CBM caused by\nspatially spreading Hg-6s spherical orbital not only induces a suitable optical\nband gap which is often too large in ionic compounds, but also promotes the\nformation and transport of n-type carriers. This study presents that Hg-based\nchalcogenide spinels are promising candidates for high-efficiency solar cells,\nand suggests that adopting cations with delocalized orbitals under the\nframework of spinel crystal is an alternative way for synthesizing the stable\nand defect-tolerant photovoltaic materials."
    },
    {
        "anchor": "OKMC simulations of Fe-C systems under irradiation: sensitivity studies: This paper continues our previous work on a nanostructural evolution model\nfor Fe-C alloys under irradiation, using Object Kinetic Monte Carlo modeling\ntechniques. We here present a number of sensitivity studies of parameters of\nthe model, such as the carbon content in the material, represented by generic\ntraps for point defects, the importance of traps, the size dependence of traps\nand the effect of the dose rate.",
        "positive": "Embedding theory for excited states with inclusion of self-consistent\n  environment screening: We present a general embedding theory of electronic excitations of a\nrelatively small, localized system in contact with an extended, chemically\ncomplex environment. We demonstrate how to include the screening response of\nthe environment into highly accurate electronic structure calculation of the\nlocalized system by means of an effective interaction between the electrons,\nwhich contains only screening processes occurring in the environment. For the\ncommon case of a localized system which constitutes an inhomogeneity in an\notherwise homogeneous system, such as a defect in a crystal, we show how matrix\nelements of the environment-screened interaction can be calculated from\ndensity-functional calculations of the homogeneous system only. We apply our\nembedding theory to the calculation of excitation energies in crystalline\nethylene."
    },
    {
        "anchor": "Atomistic Representation of Anomalies in the Failure Behaviour of\n  Nanocrystalline Silicene: Silicene, a 2D analogue of graphene, has spurred a tremendous research\ninterest in the scientific community for its unique properties essential for\nnext generation electronic devices. In this work, for the first time, we\npresent a molecular dynamics (MD) investigation to determine the fracture\nstrength and toughness of nanocrystalline silicene (nc silicene) sheet of\nvaried grain size and pre existing crack length at room temperature. Our\nresults suggest that the transition from an inverse pseudo Hall Petch to a\npseudo Hall Petch behavior in nc silicene occurs at a critical grain size of\n17.32 nm. This phenomenon is also prevalent in nanocrystalline graphene.\nHowever, nc silicene with pre existing cracks exhibits anomalous crack\npropagation and fracture toughness behaviour. We have observed two distinct\ntypes of failure mechanisms (crack sensitive and insensitive failure) and\ndevised the mechanophysical conditions under which they occur. Fracture\ntoughness calculated from both Griffiths theory and MD simulations indicate\nthat the former overpredicts the fracture toughness of nc silicene. The most\nstriking outcome, however, is that despite the presence of a pre existing\ncrack, the crack sensitivity of nc silicene is found to be dependent on the\ngrain size and their orientations. This study is the first direct comparison of\natomistic simulations to the continuum theories to predict the anomalous\nbehaviour in deformation and failure mechanisms of nc silicene.",
        "positive": "Gate-Controlled Ionization and Screening of Cobalt Adatoms on a Graphene\n  Surface: We describe scanning tunneling spectroscopy (STS) measurements performed on\nindividual cobalt (Co) atoms deposited onto backgated graphene devices. We find\nthat Co adatoms on graphene can be ionized by either the application of a\nglobal backgate voltage or by the application of a local electric field from a\nscanning tunneling microscope (STM) tip. Large screening clouds are observed to\nform around Co adatoms ionized in this way, and we observe that some intrinsic\ngraphene defects display a similar behavior. Our results provide new insight\ninto charged impurity scattering in graphene, as well as the possibility of\nusing graphene devices as chemical sensors."
    },
    {
        "anchor": "Structure and thermodynamics of defects in Na-feldspar from a neural\n  network potential: The diffusive phase transformations occurring in feldspar, a common mineral\nin the crust of the Earth, are essential for reconstructing the thermal\nhistories of magmatic and metamorphic rocks. Due to the long timescales over\nwhich these transformations proceed, the mechanism responsible for sodium\ndiffusion and its possible anisotropy has remained a topic of debate. To\nelucidate this defect-controlled process, we have developed a Neural Network\nPotential (NNP) trained on first-principle calculations of Na-feldspar (Albite)\nand its charged defects. This new force field reproduces various experimentally\nknown properties of feldspar, including its lattice parameters, elastic\nconstants as well as heat capacity and DFT-calculated defect formation\nenergies. A new type of dumbbell interstitial defect is found to be most\nfavorable and its free energy of formation at finite temperature is calculated\nusing thermodynamic integration. The necessity of including electrostatic\ncorrections before training an NNP is demonstrated by predicting more\nconsistent defect formation energies.",
        "positive": "Graphene transistors for bioelectronics: This paper provides an overview on graphene solution-gated field effect\ntransistors (SGFETs) and their applications in bioelectronics. The fabrication\nand characterization of arrays of graphene SGFETs is presented and discussed\nwith respect to competing technologies. To obtain a better understanding of the\nworking principle of solution-gated transistors, the graphene-electrolyte\ninterface is discussed in detail. The in-vitro biocompatibility of graphene is\nassessed by primary neuron cultures. Finally, bioelectronic experiments with\nelectrogenic cells are presented, confirming the suitability of graphene to\nrecord the electrical activity of cells."
    },
    {
        "anchor": "Radiation-hardened and Repairable MoS$_2$ Field Effect Devices with\n  Polymer Solid Electrolyte Gates: As human activities expand into naturally or man-made radiation-prone\nenvironment, the need for radiation-hardened (Rad-Hard) electronic hardware\nsurged. The state-of-the-art silicon-based and two-dimensional (2D) materials\nbased Rad-Hard transistors can withstand up to 1 Mrad (Si) of total ionization\ndose (TID), while higher TID tolerance is being heatedly sought after. Here we\npresent few-layer MoS$_2$ Rad-Hard field-effect transistors (FETs) with polymer\nsolid electrolyte (PSE) gate dielectrics. The MoS$_2$ PSE-FETs exhibit a TID\ntolerance of up to 3.75 Mrad (Si) at a dose rate of 523 rad (Si) s$^{-1}$ and\ncan be repaired with a moderate thermal annealing at 100 $^{\\circ}$C for 5\nminutes. Combining the excellent intrinsic radiation tolerance and the\nreparability, the MoS$_2$ PSE-FETs reach a TID tolerance of up to 10 Mrad (Si).\nComplementary metal-oxide-semiconductor (CMOS)-like MoS$_2$ PSE-inverters have\nbeen built and show similar high radiation tolerance. Furthermore, the\nfeasibility of wafer-scale Rad-Hard PSE-inverter array has been demonstrated\nusing chemical vapor deposition (CVD) grown monolayer MoS$_2$. Our studies\nuncover the potential of 2D materials based PSE devices in future Rad-Hard\nintegrated circuits (ICs).",
        "positive": "Ultrafast x-ray diffraction probe of terahertz field-driven soft mode\n  dynamics: We use ultrafast x-ray pulses to characterize the lattice response of SrTiO3\nwhen driven by strong terahertz (THz) fields. We observe transient changes in\nthe diffraction intensity with a delayed onset with respect to the driving\nfield. Fourier analysis reveals two frequency components corresponding to the\ntwo lowest energy zone-center optical modes in SrTiO3. The lower frequency mode\nexhibits clear softening as the temperature is decreased while the higher\nfrequency mode shows slight temperature dependence."
    },
    {
        "anchor": "Finite temperature magnetism of FeRh compounds: The temperature dependent stability of the magnetic phases of FeRh were\ninvestigated by means of total energy calculations with magnetic disorder\ntreated within the uncompensated disordered local moment (uDLM) approach. In\naddition, Monte Carlo simulations based on the extended Heisenberg model have\nbeen performed, using exchange coupling parameters obtained rom first\nprinciples. The crucial role and interplay of two factors in the metamagnetic\ntransition in FeRh has been revealed, namely the dependence of the Fe-Fe\nexchange coupling parameters on the temperature-governed degree of magnetic\ndisorder in the system and the stabilizing nature of the induced magnetic\nmoment on Rh-sites. An important observation is the temperature dependence of\nthese two competing factors.",
        "positive": "Measuring Dislocation Density in Aluminum with Resonant Ultrasound\n  Spectroscopy: Dislocations in a material will, when present in enough numbers, change the\nspeed of propagation of elastic waves. Consequently, two material samples,\ndiffering only in dislocation density, will have different elastic constants, a\nquantity that can be measured using Resonant Ultrasound Spectroscopy.\nMeasurements of this effect on aluminum samples are reported. They compare well\nwith the predictions of the theory."
    },
    {
        "anchor": "What can one learn about Fe-Cr alloys using M\u00f6ssbauer spectroscopy?: Applications of the M\\\"ossbauer spectroscopy (MS) in the investigation of\nFe-Cr alloys are reviewed. A high sensitivity of the hyperfine magnetic field\nto the presence of Cr atoms in the vicinity of the probe Fe atoms permits\nquantitative investigation of various aspects related both to the\ncrystallographic as well as to the magnetic phase diagram of this alloy system.\nConcerning the former, presented is the relevance of MS for determining borders\nof the miscibility gap and kinetics of the phase decomposition, distinguishing\nbetween nucleation and growth and spinodal decomposition, identifying the\nsigma-phase and studying kinetics of its precipitation. Regarding the magnetic\nphase diagram, MS is useful for determining the Curie, the N\\'eel and the\nspin-freezing temperature, hence studying paramagnetic-ferromagnetic,\nparamagnetic-antiferromagnetic and paramagnetic-spin-glass transitions. An\neffect of different heat treatments, strain and irradiation with various\nparticles on a distribution of Cr atoms in the Fe matrix is demonstrated, too.\nFor bcc-FeCr alloys relevance of MS for determining changes in spin and charge\ndensities at Fe-sites induced by neighboring Cr atoms is illustrated, as well\nas its usefulness in studying changes caused by a high-temperature sulphidation\nand oxidation. Concerning properties of sigma-FeCr alloys the application of MS\nfor determining the Curie and Debye temperature is reviewed. Application of MS\nto study an effect of magnetism on the lattice dynamics of Fe atoms in\nsigma-FeCr is also exemplified. Last but not least, determining a magnetic\ntexture and mechanical alloying is addressed.",
        "positive": "Lattice Vibrational Modes and Phonon Thermal Conductivity of Monolayer\n  MoS2: The anharmonic behavior of phonons and intrinsic thermal conductivity\nassociated with the Umklapp scattering in monolayer MoS2 sheet are investigated\nvia first-principles calculations within the framework of density functional\nperturbation theory. In contrast to the negative Gruneissen parameter occurring\nin low frequency modes in graphene, positive Gruneissen parameter in the whole\nBrillouin zone is demonstrated in monolayer MoS2 with much larger Gruneissen\nparameter for acoustic modes than that for the optical modes, suggesting that\nmonolayer MoS2 sheet possesses a positive coefficient of thermal-expansion. The\ncalculated phonon lifetimes of the infrared active modes are 5.50 and 5.72 ps\nfor E'and A2'' respectively, in good agreement with experimental result\nobtained by fitting the dielectric oscillators with the infrared reflectivity\nspectrum. The lifetime of Raman A1' mode (38.36 ps) is about 7 times longer\nthan those of the infrared modes. The dominated phonon mean free path of\nmonolayer MoS2 is less than 20 nm, about 30-fold smaller than that of graphene.\nCombined with the non-equilibrium Green's function calculations, the room\ntemperature thermal conductivity of monolayer MoS2 is found to be around 23.2\nWm-1K-1, two orders of magnitude lower than that of graphene."
    },
    {
        "anchor": "Predicting the Activity and Selectivity of Bimetallic Metal Catalysts\n  for Ethanol Reforming using Machine Learning: Machine learning is ideally suited for the pattern detection in large uniform\ndatasets, but consistent experimental datasets on catalyst studies are often\nsmall. Here we demonstrate how a combination of machine learning and\nfirst-principles calculations can be used to extract knowledge from a\nrelatively small set of experimental data. The approach is based on combining a\ncomplex machine-learning model trained on a computational library of\ntransition-state energies with simple linear regression models of experimental\ncatalytic activities and selectivities from the literature. Using the combined\nmodel, we identify the key C-C bond scission reactions involved in ethanol\nreforming and perform a computational screening for ethanol reforming on\nmonolayer bimetallic catalysts with architectures TM-Pt-Pt(111) and\nPt-TM-Pt(111) (TM = 3d transition metals). The model also predicts four\npromising catalyst compositions for future experimental studies. The approach\nis not limited to ethanol reforming but is of general use for the\ninterpretation of experimental observations as well as for the computational\ndiscovery of catalytic materials.",
        "positive": "A new material for hydrogen storage, ScAl0.8Mg0.2: A novel aluminium rich alloy for hydrogen storage has been discovered,\nScAl0.8Mg0.2, which has superior properties regarding hydrogen storage\ncapacity, kinetics and stability towards air oxidation in comparison to\nhydrogen absorption in state-of-the-art intermetallic compounds. Detailed\nanalysis of the hydrogen absorption in ScAl0.8Mg0.2 has been performed using in\nsitu synchrotron radiation powder X-ray diffraction, neutron powder diffraction\nand quantum mechanical calculations. The results from calculations and\nexperiments are in good agreement with each other."
    },
    {
        "anchor": "Electrochemical Removal of HF from Carbonate-based $LiPF_6$-containing\n  Li-ion Battery Electrolytes: Due to the hydrolytic instability of $LiPF_6$ in carbonate-based solvents, HF\nis a typical impurity in Li-ion battery electrolytes. HF significantly\ninfluences the performance of Li-ion batteries, for example by impacting the\nformation of the solid electrolyte interphase at the anode and by affecting\ntransition metal dissolution at the cathode. Additionally, HF complicates\nstudying fundamental interfacial electrochemistry of Li-ion battery\nelectrolytes, such as direct anion reduction, because it is\nelectrocatalytically relatively unstable, resulting in LiF passivation layers.\nMethods to selectively remove ppm levels of HF from $LiPF_6$-containing\ncarbonate-based electrolytes are limited. We introduce and benchmark a simple\nyet efficient electrochemical in situ method to selectively remove ppm amounts\nof HF from $LiPF_6$-containing carbonate-based electrolytes. The basic idea is\nthe application of a suitable potential to a high surface-area metallic\nelectrode upon which only HF reacts (electrocatalytically) while all other\nelectrolyte components are unaffected under the respective conditions.",
        "positive": "Magnetic proximity effect at the interface of two-dimensional materials\n  and magnetic oxide insulators: Two-dimensional (2D) materials provide a platform for developing novel\nspintronic devices and circuits for low-power electronics. In particular,\ninducing magnetism and injecting spins in graphene have promised the emerging\nfield of graphene spintronics. This review focuses on the magnetic proximity\neffect at the interface of 2D materials and magnetic oxide insulators. We\nhighlight the unique spin-related phenomena arising from magnetic exchange\ninteraction and spin-orbital coupling in 2D materials coupled with magnetic\noxides. We also describe the fabrication of multifunctional hybrid devices\nbased on spin transport. We conclude with a perspective of the field and\nhighlight challenges for the design and fabrication of 2D spintronic devices\nand their potential applications in information storage and logic devices."
    },
    {
        "anchor": "A theoretical study of thermal conductivity in single-walled boron\n  nitride nanotubes: We perform a theoretical investigation on the thermal conductivity of\nsingle-walled boron nitride nanotubes (SWBNT) using the kinetic theory. By\nfitting to the phonon spectrum of boron nitride sheet, we develop an efficient\nand stable Tersoff-derived interatomic potential which is suitable for the\nstudy of heat transport in sp2 structures. We work out the selection rules for\nthe three-phonon process with the help of the helical quantum numbers $(\\kappa,\nn)$ attributed to the symmetry group (line group) of the SWBNT. Our calculation\nshows that the thermal conductivity $\\kappa_{\\rm ph}$ diverges with length as\n$\\kappa_{\\rm ph}\\propto L^{\\beta}$ with exponentially decaying $\\beta(T)\\propto\ne^{-T/T_{c}}$, which results from the competition between boundary scattering\nand three-phonon scattering for flexure modes. We find that the two flexure\nmodes of the SWBNT make dominant contribution to the thermal conductivity,\nbecause their zero frequency locates at $\\kappa=\\pm\\alpha$ where $\\alpha$ is\nthe rotational angle of the screw symmetry in SWBNT.",
        "positive": "Trend of the magnetic anisotropy for individual Mn dopants near the\n  (110) GaAs surface: Using a microscopic finite-cluster tight-binding model, we investigate the\ntrend of the magnetic anisotropy energy as a function of the cluster size for\nan individual Mn impurity positioned in the vicinity of the (110) GaAs\nsurface,We present results of calculations for large cluster sizes, containing\napproximately 104 atoms, which have not been investigated so far. Our\ncalculations demonstrate that the anisotropy energy of a Mn dopant in bulk GaAs\nfound to be non-zero in previous tight-binding calculations, is purely a finite\nsize effect, and it vanishes as the inverse cluster size. In contrast to this,\nwe find that the splitting of the three in-gap Mn acceptor energy levels\nconverges to a finite value in the limit of infinite cluster size. For a Mn in\nbulk GaAs this feature is related to the nature of the mean-field treatment of\nthe coupling between the impurity and its nearest neighbors atoms. Moreover, we\ncalculate the trend of the anisotropy energy in the sublayers, as the Mn dopant\nis moved away from the surface towards the center of the cluster. Here the use\nof large cluster sizes allows us to position the impurity in deeper sublayers\nbelow the surface, compared to previous calculations. In particular, we show\nthat the anisotropy energy increases up to the fifth sublayer and then\ndecreases as the impurity is moved further away from the surface, approaching\nits bulk value. The present study provides important insight for experimental\ncontrol and manipulation of the electronic and magnetic properties of\nindividual Mn dopants at the semiconductor surface by means of advanced\nscanning tunneling microscopy techniques."
    },
    {
        "anchor": "An Effective Strategy to Enable Argyrodite Sulfides as Superb\n  Solid-State Electrolytes: Safeguarding Remarkable Ionic Conductivity and\n  Interfacial Stability with Electrodes: The argyrodite sulfides are getting more and more attractive as highly\npromising solid-state electrolytes (SSEs) for high-performance all-solid-state\nbatteries (ASSBs), owing to their high ionic conductivity, adequate plasticity,\nand decent mechanical strength. However, their poor incompatibility with Li\nmetal anode and high voltage cathodes and as well as serious sensitivity to air\nsignificantly hinder their practical applications. Herein, we have devised an\neffective strategy to overcome these challenging shortcomings through\nmodification of chalcogen chemistry under the guidance of theoretical modeling.\nThe resultant Li6.25PS4O1.25Cl0.75 delivered excellent electrochemical\ncompatibility with both pure Li anode and high-voltage LiCoO2 cathode, without\ndetrimental impact upon the superb ionic conductivity of the pristine sulfide.\nFurthermore, the current SSE also exhibited highly improved stability to oxygen\nand moisture in air, with further advantage being more insulating to electrons.\nThe remarkably enhanced compatibility with electrodes is attributed to in situ\nformation of solid anode electrolyte interphase (AEI) and cathode electrolyte\ninterphase (CEI) layers. The formation of in situ AEI enabled ultra-stable Li\nplating/stripping at a record high current density up to 1 mAh cm-2 in\nLi|Li6.25PS4O1.25Cl0.75|Li symmetric cells over 1800 hours. The in situ CEI\nfacilitated protection of the SSE from decomposition at elevated voltage.\nConsequently, the synergistic effect of AEI and CEI helped the\nLiCoO2|Li6.25PS4O1.25Cl0.75|Li battery cell to achieve markedly better cycling\nstability than that using the pristine Li6PS5Cl as SSE, at a high areal loading\nof the active cathode material (4 mg cm-2). This work adds a desirable SSE in\nthe argyrodite sulfide family, so that high-performance solid battery cells\ncould even be fabricated in ambient air.",
        "positive": "Practical photoemission characterization of molecular films and related\n  interfaces: Even though the term `organic electronics' evokes rather organic devices, a\nsignificant part of its scope deals with physical properties of `active\nelements' such as organic films and interfaces. Examination of the film growth\nand the evolution of the interface formation are particularly needful for the\nunderstanding a mechanism controlling their final properties. Performing such\nexperiments in an ultra-high vacuum allows both to `stretch' the time scale for\npseudo real-time observations and to control properties of the probed systems\non the atomic level. Photoemission technique probes directly electronic and\nchemical structure and it has thereby established among major tools employed in\nthe field. This review primarily focuses to electronic properties of oligomeric\nmolecular films and their interfaces examined by photoemission. Yet, it does\nnot aspire after a complete overview on the topic; it rather aims to otherwise\nstandard issues encountered at the photoemission characterization and analysis\nof the organic materials, though requiring to consider particularities of\nmolecular films in terms of the growth, electronic properties, and their\ncharacterization and analysis. In particular, the fundamental electronic\nparameters of molecular films such as the work function, the ionization energy,\nand the interfacial energy level alignment, and their interplay, will be\npursued with considering often neglected influence of the molecular\norientation. Further, the implication on the band bending in molecular films\nbased on photoemission characterization, and a model on the driving mechanism\nfor the interfacial energy level alignment will be addressed."
    },
    {
        "anchor": "Magnetic Interactions in BiFeO$_3$: a First-Principles Study: First-principles calculations, in combination with the four-state energy\nmapping method, are performed to extract the magnetic interaction parameters of\nmultiferroic BiFeO$_3$. Such parameters include the symmetric exchange (SE)\ncouplings and the Dzyaloshinskii-Moriya (DM) interactions up to second nearest\nneighbors, as well as the single ion anisotropy (SIA). All magnetic parameters\nare obtained not only for the $R3c$ structural ground state, but also for the\n$R3m$ and $R\\bar{3}c$ phases in order to determine the effects of\nferroelectricity and antiferrodistortion distortions, respectively, on these\nmagnetic parameters. In particular, two different second-nearest neighbor\ncouplings are identified and their origins are discussed in details. Moreover,\nMonte-Carlo (MC) simulations using a magnetic Hamiltonian incorporating these\nfirst-principles-derived interaction parameters are further performed. They\nresult (i) not only in the accurate prediction of the spin-canted G-type\nantiferromagnetic structure and of the known magnetic cycloid propagating along\na $<$1$\\bar{1}$0$>$ direction, as well as their unusual characteristics (such\nas a weak magnetization and spin-density-waves, respectively); (ii) but also in\nthe finding of another cycloidal state of low-energy and that awaits to be\nexperimentally confirmed. Turning on and off the different magnetic interaction\nparameters in the MC simulations also reveal the precise role of each of them\non magnetism.",
        "positive": "Simulation of High Conversion Efficiency and Open-circuit Voltages Of\n  \u03b1-si/poly-silicon Solar Cell: The P+ {\\alpha}-Si /N+ polycrystalline solar cell is molded using the AMPS-1D\ndevice simulator to explore the new high efficiency thin film poly-silicon\nsolar cell. In order to analyze the characteristics of this device and the\nthickness of N+ poly-silicon, we consider the impurity concentration in the N+\npoly-silicon layer and the work function of transparent conductive oxide (TCO)\nin front contact in the calculation. The thickness of N+ poly-silicon has\nlittle impact on the device when the thickness varies from 20 {\\mu}m to 300\n{\\mu}m. The effects of impurity concentration in polycrystalline are analyzed.\nThe conclusion is drawn that the open-circuit voltage (Voc) of P+ {\\alpha}-Si\n/N+ polycrystalline solar cell is very high, reaching 752 mV, and the\nconversion efficiency reaches 9.44%. Therefore, based on the above optimum\nparameters the study on the device formed by P+ {\\alpha}-Si/N+ poly-silicon is\nsignificant in exploring the high efficiency poly-silicon solar cell."
    },
    {
        "anchor": "Synthesis and study of fcc-Co derived from isostructural Co4N: This work demonstrates synthesis and study of fcc-Co derived from an\nisostructural Co4N. Diffusion measurements carried out in this work, reveal\nthat N self-diffusion is the swiftest in Co4N compared to other transition\nmetal nitrides or even the mononitride CoN. By the application of a high\nsubstrate temperature (Ts) growth or thermal annealing temperature (Ta); N\ndiffuses out from the fcc-Co4N above 573 K leaving behind a high purity fcc-Co\nphase. Generally, Co grows in a hcp structure and a (partial) hcp to fcc-Co\ntransformation takes place around 700 K or above 70 GPa. The proposed route\nthrough nitridation and diffusion of N not only bring down the phase transition\ntemperature, an impurity present in the form of hcp-Co can be avoided\naltogether. Oriented Co4N(111) thin films were grown using a CrN(111) template\non a quartz substrate using a dc magnetron sputtering. Samples were grown at\ndifferent Ts or room temperature grown Co4N samples were annealed at different\nTa. Analysis using x-ray diffraction, N K-edge x-ray absorption, x-ray\nphotoelectron and secondary ion mass spectroscopy confirmed the formation of\nfcc-Co4N or fcc-Co phases. It was found that Co-N bonding and N concentration\nget significantly reduced at a high Ts or Ta. Magnetization measurements\ncombining ex-situ and in-situ magneto-optical Kerr effect showed differences in\nanisotropy and coercivity of Co4N and fcc-Co samples. Combining structural,\nelectronic and magnetization measurements, it has been observed that a high\npurity fcc-Co can be conveniently derived from the isostructural Co4N aided by\nan exceptionally high N self-diffusion in Co4N.",
        "positive": "Routing the emission of a near-surface light source by a magnetic field: Magneto-optical phenomena such as the Faraday and Kerr effects play a\ndecisive role for establishing control over polarization and intensity of\noptical fields propagating through a medium. Intensity effects where the\ndirection of light emission depends on the orientation of the external magnetic\nfield are of particular interest as they can be used for routing the light. We\nreport on a new class of transverse emission phenomena for light sources\nlocated in the vicinity of a surface, where directionality is established\nperpendicularly to the externally applied magnetic field. We demonstrate the\nrouting of emission for excitons in a diluted-magnetic-semiconductor quantum\nwell. The directionality is significantly enhanced in hybrid plasmonic\nsemiconductor structures due to the generation of plasmonic spin fluxes at the\nmetal-semiconductor interface."
    },
    {
        "anchor": "Driving magnetic skyrmions with microwave fields: We show theoretically by numerically solving the Landau-Lifshitz-Gilbert\nequation with a classical spin model on a two-dimensional system that both\nmagnetic skyrmions and skyrmion lattices can be moved with microwave magnetic\nfields. The mechanism is enabled by breaking the axial symmetry of the\nskyrmion, for example through application of a static in-plane external field.\nThe net velocity of the skyrmion depends on the frequency and amplitude of the\nmicrowave fields as well as the strength of the in-plane field. The maximum\nvelocity is found where the frequency of the microwave coincides with the\nresonance frequency of the breathing mode of the skyrmions.",
        "positive": "AlGaAs/GaAs/AlGaAs quantum wells as a sensitive tool for the MOVPE\n  reactor environment: We present in this work a simple Quantum Well (QW) structure consisting of\nGaAs wells with AlGaAs barriers as a probe for measuring the performance of\narsine purifiers within a MetalOrganic Vapour Phase Epitaxy system. Comparisons\nbetween two different commercially available purifiers are based on the\nanalysis of low temperature photoluminescence emission spectra from thick QWs,\ngrown on GaAs substrates misoriented slightly from (100). Neutral excitons\nemitted from these structures show extremely narrow linewidths, comparable to\nthose which can be obtained by Molecular Beam Epitaxy in an ultra-high vacuum\nenvironment, suggesting that purifications well below the 1ppb level are needed\nto achieve high quality quantum well growth."
    },
    {
        "anchor": "Tuning Thermal Conductivity of Hybrid Perovskites through Halide\n  Alloying: Tuning the thermal transport properties of hybrid halide perovskites is\ncritical for their applications in optoelectronics, thermoelectrics, and\nphotovoltaics. Here, we demonstrate an effective strategy to modulate the\nthermal transport property of hybrid perovskites by halide alloying. A highly\ntunable thermal conductivity of mixed-halide hybrid perovskites is achieved due\nto halide-alloying and structural distortion. Our experimental measurements\nshow that the room temperature thermal conductivity of MAPb(BrxI1-x)3 (x = 0-1)\ncan be largely modulated from 0.27 W/mK (x = 0.5) to 0.47 W/mK (x = 1).\nMolecular dynamics simulations further demonstrate that the thermal\nconductivity reduction of hybrid halide perovskites results from the\nsuppression of the mean free paths of the low-frequency acoustic and optical\nphonons. It is found that halide alloying and the induced structural distortion\ncan largely increase the scatterings of optical and acoustic phonons,\nrespectively. The confined diffusion of MA+ cations in the octahedra cage is\nfound to act as an additional thermal transport channel in hybrid perovskites\nand can contribute around 10-20% of the total thermal conductivity. Our\nfindings provide a strategy for tailoring the thermal transport in hybrid\nhalide perovskites which may largely benefit their related applications.",
        "positive": "Cubic-scaling algorithm and self-consistent field for the random-phase\n  approximation with second-order screened exchange: The random-phase approximation with second-order screened exchange\n(RPA+SOSEX) is a model of electron correlation energy with two caveats: its\naccuracy depends on an arbitrary choice of mean field, and it scales as\n$\\mathcal{O}(n^5)$ operations and $\\mathcal{O}(n^3)$ memory for $n$ electrons.\nWe derive a new algorithm that reduces its scaling to $\\mathcal{O}(n^3)$\noperations and $\\mathcal{O}(n^2)$ memory using controlled approximations and a\nnew self-consistent field that approximates Brueckner coupled-cluster doubles\n(BCCD) theory with RPA+SOSEX, referred to as Brueckner RPA (BRPA) theory. The\nalgorithm comparably reduces the scaling of second-order\nM$\\mathrm{{\\o}}$ller-Plesset (MP2) perturbation theory with smaller cost\nprefactors than RPA+SOSEX. Within a semiempirical model, we study H$_2$\ndissociation to test accuracy and H$_n$ rings to verify scaling."
    },
    {
        "anchor": "Gazing at crystal balls: Electron backscatter diffraction pattern\n  analysis and cross correlation on the sphere: We present spherical analysis of electron backscatter diffraction (EBSD)\npatterns with two new algorithms: (1) band localisation and band profile\nanalysis using the spherical Radon transform; (2) orientation determination\nusing spherical cross correlation. These new approaches are formally introduced\nand their accuracies are determined using dynamically simulated patterns. We\ndemonstrate their utility with an experimental dataset obtained from ferritic\niron. Our results indicate that the analysis of EBSD patterns on the surface of\nthe sphere provides an elegant method of revealing information from these rich\nsources of crystallographic data.",
        "positive": "Spark plasma sintering synthesis of ReB2-type medium-entropy diboride\n  (W1/3Re1/3Ru1/3)B2 with high hardness: A new medium-entropy diboride (MEDB) (W1/3Re1/3Ru1/3)B2 has been synthesized\nby spark plasma sintering of elemental powders at 1600 oC. Despite the\ndissimilar structures of WB2, ReB2 and RuB2, the sintered MEDB consists of a\nsingle hexagonal ReB2-type phase (space group P63/mmc) with a relative density\nof 94.2% and an average grain size of 6.8 $\\pm$ 2.2 um. Structural refinement\nand electron microscopy measurements show that the W, Re, and Ru atoms occupy\nthe same crystallographic site and are distributed uniformly in the lattice.\nThe (W1/3Re1/3Ru1/3)B2 MEDB has Vickers hardnesses of 30.7 GPa at a load of\n0.49 N and 20.5 GPa at a load of 9.8 N, which are comparable or higher than\nthose reported for individual binary counterparts."
    },
    {
        "anchor": "Electric Field-induced Charge Transport in Redox-active Molecular\n  Junctions: The formation of well-defined three-dimensional (3D) redox-active molecular\nnanostructures at the electrode surfaces may open additional routes to achieve\nhigher conductance in molecular junctions (MJs). We report here experimental\nand theoretical charge transport analysis on electroactive\nruthenium(II)-tri(phenanthroline) [Ru(Phen)3]-based molecular junctions\ncovalently grown on patterned ITO electrode. Thicknesses of the molecular\nlayers are varied between 4 to 13 nm, thanks to the potential-driven\nelectrochemical technique to achieve it. A thin layer of Al was deposited on\ntop contact over ITO/ Ru(Phen)3 to fabricate large-area solid-state molecular\njunctions with a stacking configuration of ITO/[Ru(Phen)3]4nm, 10nm, 13nm/Al.\nThe electrified molecular junctions show LUMO-mediated electron-driven resonant\ncharge conduction with attenuation in conductance as a function of the length\nof Ru(Phen)3 layers (\\b{eta} = 0.48 to 0.60 nm-1). Molecular junctions\nconsisting of 4 nm Ru(Phen)3 layers follow quantum tunneling, while the thicker\njunctions (10, and 13 nm) follow Poole-Frenkel and electric-field induced\ncharge conduction. Considering the energy level of frontier molecular orbitals,\nFermi energy of ITO, and Al contact, a mechanism of symmetric current-voltage\nfeatures with respect to the bias-polarity is predicted. The present work\ndescribes a simple, controllable, low-cost, and versatile approach to\nfabricating 3D molecular assembly for mimicking conventional electronic\nfunctions.",
        "positive": "A Map of the Inorganic Ternary Metal Nitrides: Exploratory synthesis in novel chemical spaces is the essence of solid-state\nchemistry. However, uncharted chemical spaces can be difficult to navigate,\nespecially when materials synthesis is challenging. Nitrides represent one such\nspace, where stringent synthesis constraints have limited the exploration of\nthis important class of functional materials. Here, we employ a suite of\ncomputational materials discovery and informatics tools to construct a large\nstability map of the inorganic ternary metal nitrides. Our map clusters the\nternary nitrides into chemical families with distinct stability and\nmetastability, and highlights hundreds of promising new ternary nitride spaces\nfor experimental investigation--from which we experimentally realized 7 new Zn-\nand Mg-based ternary nitrides. By extracting the mixed metallicity, ionicity,\nand covalency of solid-state bonding from the DFT-computed electron density, we\nreveal the complex interplay between chemistry, composition, and electronic\nstructure in governing large-scale stability trends in ternary nitride\nmaterials."
    },
    {
        "anchor": "Carrier Concentration Dependencies of Magnetization & Transport in\n  Ga1-xMnxAs1-yTey: We have investigated the transport and magnetization characteristics of\nGa1-xMnxAs intentionally compensated with shallow Te donors. Using ion\nimplantation followed by pulsed-laser melting, we vary the Te compensation and\ndrive the system through a metal-insulator transition (MIT). This MIT is\nassociated with enhanced low-temperature magnetization and an evolution from\nconcave to convex temperature-dependent magnetization.",
        "positive": "A novel approach to assess hydrogen embrittlement (HE) susceptibility\n  and mechanisms in high strength martensitic steels: A rapid fracture test in four-point bending is proposed to assess hydrogen\nembrittlement (HE) susceptibility of high strength martensitic steels. The\nnovelty of this technique is the rapid rate of loading, whereas conventional\napproaches require prolonged slow strain rate testing. The essential\nfractographic features required to identify the mechanisms of HE failure remain\nevident, despite the fast loading conditions. To demonstrate these attributes,\ntwo quenched and tempered steels at two different strength levels were tested,\nwith and without pre-charging of hydrogen. Stress coupled hydrogen diffusion\nfinite element analysis (FEA) was performed to calculate both stress and\nhydrogen concentration distributions. In addition to fractographic analysis, a\nmechanistic description rooted in hydrogen enhanced decohesion (HEDE) mechanism\nwas used to corroborate the mechanical test data. The study shows that the\napproach is capable of quantifying HE susceptibility by being responsive to key\nfactors affecting hydrogen induced fracture, thus developing further\nunderstanding on the HE of martensitic steels."
    },
    {
        "anchor": "Imaging the interface of epitaxial graphene with silicon carbide via\n  scanning tunneling microscopy: Graphene grown epitaxially on SiC has been proposed as a material for\ncarbon-based electronics. Understanding the interface between graphene and the\nSiC substrate will be important for future applications. We report the ability\nto image the interface structure beneath single-layer graphene using scanning\ntunneling microscopy. Such imaging is possible because the graphene appears\ntransparent at energies of 1 eV above or below the Fermi energy. Our analysis\nof calculations based on density functional theory shows how this transparency\narises from the electronic structure of a graphene layer on a SiC substrate.",
        "positive": "Designable hybrid sonic crystals for transportation and division of\n  acoustic images: Conventional sonic crystal (SC) devices designed for acoustic imaging can\nfocus acoustic waves from an input source into only one image but not\nmulti-images. Furthermore the output position of formed image cannot be\ndesigned at will. In this paper, we propose the hybrid SC imaging devices to\nachieve multi-images from one-source-input along with the designable\nimage-positions. The proposed hybrid devices can image acoustic waves radiated\nboth from point source and Gaussian beam, which different from conventional SC\nimaging devices that only applies to point source. These multi-functional but\nstill simple and easy-to-fabricate devices are believed to find extensive\napplications, particularly in ultrasonic photography and compact acoustic\nimaging."
    },
    {
        "anchor": "Spin Hall effect in prototype Rashba ferroelectrics GeTe and SnTe: Ferroelectric Rashba semiconductors (FERSC) have recently emerged as a\npromising class of spintronics materials. The peculiar coupling between spin\nand polar degrees of freedom responsible for several exceptional properties,\nincluding ferroelectric switching of Rashba spin texture, suggests that the\nelectron's spin could be controlled by using only electric fields. In this\nregard, recent experimental studies revealing charge-to-spin interconversion\nphenomena in two prototypical FERSC, GeTe and SnTe, appear extremely relevant.\nHere, by employing density functional theory calculations, we investigate spin\nHall effect (SHE) in these materials and show that it can be large either in\nferroelectric or paraelectric structure. We further explore the compatibility\nbetween doping required for the practical realization of SHE in semiconductors\nand polar distortions which determine Rashba-related phenomena in FERSC, but\nwhich could be suppressed by free charge carriers. Based on the analysis of the\nlone pairs which drive ferroelectricity in these materials, we have found that\nthe polar displacements in GeTe can be sustained up to a critical hole\nconcentration of over $\\sim 10^{21}$/cm$^{3}$, while the tiny distortions in\nSnTe vanish at a minimal level of doping. Finally, we have estimated spin Hall\nangles for doped structures and demonstrated that the spin Hall effect could be\nindeed achieved in a polar phase. We believe that the confirmation of spin Hall\neffect, Rashba spin textures and ferroelectricity coexisting in one material\nwill be helpful for design of novel multifunctional spintronics devices\noperating without magnetic fields.",
        "positive": "High-pressure BaCN$_2$ phases explored by genetic algorithm: Polymers containing nitrogen have attracted much attention in connection with\ntheir application to high energy density materials (HEDMs), in which energy is\ninherent in the triple bond. It is an interesting question whether such\npolymerized phases appear in the high-pressure phase of metal carbodiimide\nMCN$_2$, of which synthesis have been reported in recent years, but few studies\nhave investigated the crystal structure at high pressure. We have adopted a\nstructure search based on the genetic algorithm coupled with ab initio\nelectronic structure calculations to investigate possible crystal structures\nthat may appear in the high-pressure phase of BaCN$_2$. The structure search\nsuccessfully reproduced the previously reported crystal structures in the lower\npressure range. With confirmed reliability of its predictive ability, the\ngenetic search further predicts a polymerized phase with Ima2 appearing at\nhigher pressure above 42 GPa. The polymerized phase takes the structure of a\nlinear network of CN$_3$ planar triangular units. It is understood that the\nanion site units CN$_2$, which are close to each other under high pressure,\nform covalent bonds directly with each other and stabilize the phase."
    },
    {
        "anchor": "Dewetting of a thin polymer film under shear: The objective of this work is to study the role of shear on the rupture of\nultrathin polymer films. To do so, a finite-difference numerical scheme for the\nresolution of the thin film equation was set up taking into account capillary\nand van der Waals (vdW) forces. This method was validated by comparing the\ndynamics obtained from an initial harmonic perturbation to established\ntheoretical predictions. With the addition of shear, three regimes have then\nbeen evidenced as a function of the shear rate. In the case of low shear rates\nthe rupture is delayed when compared to the no-shear problem, while at higher\nshear rates it is even suppressed: the perturbed interface goes back to its\nunperturbed state over time. In between these two limiting regimes, a transient\none in which shear and vdW forces balance each other, leading to a\nnon-monotonic temporal evolution of the perturbed interface, has been\nidentified. While a linear analysis is sufficient to describe the rupture time\nin the absence of shear, the nonlinearities appear to be essential otherwise.",
        "positive": "Extended Depth of Field for High Resolution Scanning Transmission\n  Electron Microscopy: Aberration-corrected scanning transmission electron microscopes (STEM)\nprovide sub-angstrom lateral resolution; however, the large convergence angle\ngreatly reduces the depth of field. For microscopes with a small depth of\nfield, information outside of the focal plane quickly becomes blurred and less\ndefined. It may not be possible to image some samples entirely in focus.\nExtended depth-of-field techniques, however, allow a single image, with all\nareas in-focus, to be extracted from a series of images focused at a range of\ndepths. In recent years, a variety of algorithmic approaches have been employed\nfor bright field optical microscopy. Here, we demonstrate that some established\noptical microscopy methods can also be applied to extend the ~6 nm depth of\nfocus of a 100 kV 5th-order aberration-corrected STEM (alpha_max = 33 mrad) to\nimage Pt-Co nanoparticles on a thick vulcanized carbon support. These\ntechniques allow us to automatically obtain a single image with all the\nparticles in focus as well as a complimentary topography map."
    },
    {
        "anchor": "Magnetic asymmetry induced anomalous spin-orbit torque in IrMn: We demonstrate an anomalous spin-orbit torque induced by the broken magnetic\nsymmetry in the antiferromagnet IrMn. We study the magnetic structure of three\nphases of IrMn thin films using neutron diffraction technique. The magnetic\nmirror symmetry M' is broken laterally in both L10-IrMn and L12-IrMn3 but not\n{\\gamma}-IrMn3. We observe an out-of-plane damping-like spin-orbit torque in\nboth L10-IrMn/permalloy and L12-IrMn3/permalloy bilayers but not in\n{\\gamma}-IrMn3/permalloy. This is consistent with both the symmetry analysis on\nthe effects of a broken M' on spin-orbit torque and the theoretical predictions\nof the spin Hall effect and the Rashba-Edelstein effect. In addition, the\nmeasured spin-orbit torque efficiencies are 0.61+-0.01, 1.01+-0.03 and\n0.80+-0.01 for the L10, L12 and {\\gamma} phases, respectively. Our work\nhighlights the critical roles of the magnetic asymmetry in spin-orbit torque\ngeneration.",
        "positive": "Application-oriented strain-hardening engineering of high-manganese\n  steels: The outstanding mechanical properties of high-manganese steels (HMnS) are a\nresult of their high strain-hardenability. That is facilitated by strong\nsuppression of dynamic recovery, predominant planar glide, and the activation\nof additional deformation mechanisms, such as transformation-induced plasticity\n(TRIP) and twinning-induced plasticity (TWIP). However, depending on the final\napplication, strongly differing requirements on the mechanical properties of\nHMnS are of relevance. In order to design HMnS for specific applications,\nmulti-scale material simulation under consideration of the processing\nconditions that allows for prediction of the final mechanical properties is\nrequired, i.e. strain-hardening engineering based on integrated computational\nmaterials engineering (ICME). In this work, we present an approach that employs\nalloy selection by stacking-fault energy calculations, which enables\nactivation/suppression of specific deformation mechanisms. Tailored\nmanufacturing, e.g. by thermo-mechanical treatment, severe plastic deformation\nor additive manufacturing, provides possibilities to make use of the\nstrain-hardenability during and after processing to define the mechanical\nproperties. A computational approach for alloy and process design will be\ndiscussed."
    },
    {
        "anchor": "Observation of Surface-Avoiding Waves: A New Class of Extended States in\n  Periodic Media: Coherent time-domain optical experiments on GaAs-AlAs superlattices reveal\nthe exis-tence of an unusually long-lived acoustic mode at ~ 0.6 THz, which\ncouples weakly to the environment by evading the sample boundaries. Classical\nas well as quantum states that steer clear of surfaces are generally shown to\noccur in the spectrum of periodic struc-tures, for most boundary conditions.\nThese surface-avoiding waves are associated with frequencies outside forbidden\ngaps and wavevectors in the vicinity of the center and edge of the Brillouin\nzone. Possible consequences for surface science and resonant cavity\nap-plications are discussed.",
        "positive": "Theory of Chirality Induced Spin Selectivity: Progress and Challenges: We provide a critical overview of the theory of the chirality-induced spin\nselectivity (CISS) effect, i.e., phenomena in which the chirality of molecular\nspecies imparts significant spin selectivity to various electron processes.\nBased on discussions in a recently held workshop, and further work published\nsince, we review the status of CISS effects - in electron transmission,\nelectron transport, and chemical reactions. For each, we provide a detailed\ndiscussion of the state-of-the-art in theoretical understanding and identify\nremaining challenges and research opportunities."
    },
    {
        "anchor": "Proper Orthogonal Descriptors for Efficient and Accurate Interatomic\n  Potentials: We present the proper orthogonal descriptors for efficient and accuracy\nrepresentation of the potential energy surface. The potential energy surface is\nrepresented as a many-body expansion of parametrized potentials in which the\npotentials are functions of atom positions and parameters. The Karhunen-Lo\\`eve\n(KL) expansion is employed to decompose the parametrized potentials into a set\nof proper orthogonal descriptors (PODs). Because of the rapid convergence of\nthe KL expansion, relevant snapshots can be sampled exhaustively to represent\nthe atomic neighborhood environment accurately with a small number of\ndescriptors. The proper orthogonal descriptors are used to develop interatomic\npotentials by using a linear expansion of the descriptors and determining the\nexpansion coefficients from a weighted least-squares regression against a\ndensity functional theory (DFT) training set. We present a comprehensive\nevaluation of the POD potentials on previously published DFT data sets\ncomprising Li, Mo, Cu, Ni, Si, Ge, and Ta elements. The data sets represent a\ndiverse pool of metals, transition metals, and semiconductors. The accuracy of\nthe POD potentials are comparable to that of state-of-the-art machine learning\npotentials such as the spectral neighbor analysis potential (SNAP) and the\natomic cluster expansion (ACE).",
        "positive": "Tunable Band Structure Effects on Ballistic Transport in Graphene\n  Nanoribbons: Graphene nanoribbons (GNR) in mutually perpendicular electric and magnetic\nfields are shown to exhibit dramatic changes in their band structure and\nelectron transport properties. A strong electric field across the ribbon\ninduces multiple chiral Dirac points, closing the semiconducting gap in\narmchair GNR's. A perpendicular magnetic field induces partially formed Landau\nlevels as well as dispersive surface-bound states. Each of the applied fields\non its own preserves the even symmetry $E_{k} = E_{-k}$ of the subband\ndispersion. When applied together, they reverse the dispersion parity to be odd\nand gives $E_{e,k} = -E_{h,-k}$ and mix the electron and hole subbands within\nthe energy range corresponding to the change in potential across the ribbon.\nThis leads to oscillations of the ballistic conductance within this energy\nrange."
    },
    {
        "anchor": "Topological Graph-based Analysis of Solid-State Ion Migration: To accelerate the development of novel ion-conducting materials, we present a\ngeneral graph-theoretic analysis framework for ion migration in any crystalline\nstructure. The nodes of the graph represent metastable sites of the migrating\nion and the edges represent discrete migration events between adjacent sites.\nStarting from a collection of possible metastable migration sites, the\nframework assigns a weight to the edges by calculating the individual migration\nenergy barriers between those sites. Connected pathways in the periodic\nsimulation cell corresponding to macroscopic ion migration are identified by\nsearching for the lowest-cost cycle in the periodic migration graph. To\nexemplify the utility of the framework, we present the automatic analyses of Li\nmigration in different polymorphs of VO(PO4), with the resulting identification\nof two distinct crystal structures with simple migration pathways demonstrating\noverall < 300 meV migration barriers.",
        "positive": "Intermediate phase in the oxidative hydrothermal synthesis of potassium\n  jarosite, a model kagome antiferromagnet: The jarosite family of minerals contain antiferromagnetically coupled Fe3+\nions that make up the kagome network. This geometric arrangement of the Fe3+\nions causes magnetic frustration that results in exotic electronic ground\nstates, e.g. spin glasses and spin liquids. Synthesic research into jarosites\nhas focused on producing near perfect stoichiometry to eliminate possible\nmagnetic disorder. An new oxidative synthesis method has been devel-oped for\nthe potassium, sodium, rubidium and ammonium jarosites that leads to high Fe\ncoverage. We show through the identification of a meta-stable intermediate,\nusing powder X-ray diffraction, how near perfect Fe coverage arises using this\nmethod. Understanding this new mechanism for jarosite formation suggests that\nis it possible to synthesis hydronium jarosite, an unconventional spin glass,\nwith a very high Fe coverage."
    },
    {
        "anchor": "Spectroscopic investigations of phonons in epitaxial graphene: The interaction of graphene with metallic substrates reveals phenomena and\nproperties of great relevance for applications in nanotechnology. In this\nreview, the vibrational characterization by means of various inelastic\nscattering spectroscopies are surveyed for graphene epitaxially grown on metals\nand transition carbides. In particular, the manifestations of electron-phonon\ninteraction, such as Kohn anomalies, the evaluation of elastic properties and\nthe nanoscale control of phonon modes are presented and discussed.",
        "positive": "First-principles modeling of ferroelectric capacitors via constrained-D\n  calculations: First-principles modeling of ferroelectric capacitors presents several\ntechnical challenges, due to the coexistence of metallic electrodes, long-range\nelectrostatic forces and short-range interface chemistry. Here we show how\nthese aspects can be efficiently and accurately rationalized by using a\nfinite-field density-functional theory formalism in which the fundamental\nelectrical variable is the displacement field D. By performing calculations on\nmodel Pt/BaTiO3/Pt and Au/BaZrO3/Au capacitors we demonstrate how the\ninterface-specific and bulk-specific properties can be identified and\nrigorously separated. Then, we show how the electrical properties of capacitors\nof arbitrary thickness and geometry (symmetric or asymmetric) can be readily\nreconstructed by using such information. Finally, we show how useful\nobservables such as polarization and dielectric, piezoelectric and\nelectrostrictive coefficients are easily evaluated as a byproduct of the above\nprocedure. We apply this methodology to elucidate the relationship between\nchemical bonding, Schottky barriers and ferroelectric polarization at\nsimple-metal/oxide interfaces. We find that BO2-electrode interfaces behave\nanalogously to a layer of linear dielectric put in series with a bulk-like\nperovskite film, while a significant non-linear effect occurs at AO-electrode\ninterfaces."
    },
    {
        "anchor": "Fluorescence resonance energy transfer between organic dyes adsorbed\n  onto nano-clay and Langmuir-Blodgett (LB) films: In this communication we investigate two dyes N,N' -dioctadecyl thiacyanine\nperchlorate (NK) and octadecyl rhodamine B chloride (RhB) in Langmuir and\nLangmuir-Blodgett (LB) films with or with out a synthetic clay laponite.\nObserved changes in isotherms of RhB in absence and presence of nano-clay\nplatelets indicate the incorporation of clay platelets onto RhB-clay hybrid\nfilms. AFM image confirms the incorporation of clay in hybrid films. FRET was\nobserved in clay dispersion and LB films with and without clay. Efficiency of\nenergy transfer was maximum in LB films with clay.",
        "positive": "Solving Free Boundary Problems in Alloy Solidification under Universal\n  Cooling Conditions: The kinetics of interfaces in alloy solidification pose a classic free\nboundary problem. This paper introduces an approach that amalgamates the\ndistinctive characteristics of sharp and diffuse interface models. The motion\nof the diffuse interface is governed by the phase-field equation featuring a\ntraveling wave function [I. Steinbach, Modell. Simul. Mater. Sci. Eng. 17(7),\n073001 (2009)]. To emulate solute rejection in the sharp interface model, the\nconcept of the middle-obstacle and the casting operation are employed.\nMoreover, the undercooling along the interface normal is flattened to minimize\nthe impact of bulk undercooling in the interface and the associated effects,\nsuch as stretching and arc-length diffusion. Notably, the results for interface\nkinetics under both equilibrium and non-equilibrium conditions closely\napproximate their analytical solutions, all achieved with artificially wide\ninterfaces and comparatively low computational cost."
    },
    {
        "anchor": "Spin-Orbit Torque Engineering in \u03b2-W/CoFeB Heterostructures via Ta\n  and V Alloying at Interfaces: Spin-orbit torque manifested as an accumulated spin-polarized moment at\nnonmagnetic normal metal, and ferromagnet interfaces is a promising\nmagnetization switching mechanism for spintronic devices. To fully exploit this\nin practice, materials with a high spin Hall angle, i.e., a charge-to-spin\nconversion efficiency, are indispensable. To date, very few approaches have\nbeen made to devise new nonmagnetic metal alloys. Moreover, new materials need\nto be compatible with semiconductor processing. Here we introduce W-Ta and W-V\nalloys and deploy them at the interface between $\\beta$-W/CoFeB layers. First,\nspin Hall conductivities of W-Ta and W-V structures with various compositions\nare carried out by first-principles band calculations, which predict the spin\nHall conductivity of the W-V alloy is improved from $-0.82 \\times 10^3$ S/cm\nthat of W to $-1.98 \\times 10^3$ S/cm. Subsequently, heterostructure\nfabrication and spin-orbit torque properties are characterized experimentally.\nBy alloying $\\beta$-W with V at a concentration of 20 at%, we observe a large\nenhancement of the absolute value of spin Hall conductivity of up to $-(2.77\n\\pm 0.31) \\times 10^3$ S/cm. By employing X-ray diffraction and scanning\ntransmission electron microscopy, we further explain the enhancement of\nspin-orbit torque efficiency is stemmed from W-V alloy between W and CoFeB.",
        "positive": "Macromagnetic simulation for reservoir computing utilizing spin dynamics\n  in magnetic tunnel junctions: The figures-of-merit for reservoir computing (RC), using spintronics devices\ncalled magnetic tunnel junctions (MTJs), are evaluated. RC is a type of\nrecurrent neural network. The input information is stored in certain parts of\nthe reservoir, and computation can be performed by optimizing a linear\ntransform matrix for the output. While all the network characteristics should\nbe controlled in a general recurrent neural network, such optimization is not\nnecessary for RC. The reservoir only has to possess a non-linear response with\nmemory effect. In this paper, macromagnetic simulation is conducted for the\nspin-dynamics in MTJs, for reservoir computing. It is determined that the\nMTJ-system possesses the memory effect and non-linearity required for RC. With\nRC using 5-7 MTJs, high performance can be obtained, similar to an echo-state\nnetwork with 20-30 nodes, even if there are no magnetic and/or electrical\ninteractions between the magnetizations."
    },
    {
        "anchor": "A One-Dimensional Coordination Polymer, BBDTA-InCl4; Possible\n  Spin-Peierls Transition with High Critical Temperature of 108 K: We have studied the crystal structure and magnetic properties of the organic\nradical cation salt, BBDTA-InCl4. This material formed a one-dimensional\ncoordination polymer, whose structure was characteristic of inorganic\nspin-Peierls materials. Magnetic measurements indicated the spin-Peierls\ntransition like behavior at 108 K, which was higher than those typically\nobserved for the other organic spin-Peierls materials. The structural aspects\nof the lattice distortion from X-ray diffraction measurements at 50 K have been\ndiscussed.",
        "positive": "Luminescence of a ZnO:Ga Crystal upon Excitation in Vacuum UV Region: The spectral--kinetic characteristics of a ZnO:Ga single crystal upon\nexcitation in the vacuum UV region have been studied. At a temperature of 8 K,\nthe exciton luminescence line peaking at 3.356 eV has an extremely small\nhalf-width (7.2 meV) and a short decay time (360 ps). In the visible range, a\nwide luminescence band peaking at ~2.1 eV with a long luminescence time at 8 K\nand a decay time in the nanosecond range at 300 K is observed. The luminescence\nexcitation spectra of ZnO:Ga have been measured in the range from 4 to 12.5 eV"
    },
    {
        "anchor": "Exciton-photocarrier interference in mixed lead-halide-perovskite\n  nanocrystals: The use of semiconductor nanocrystals in scalable quantum technologies\nrequires characterization of the exciton coherence dynamics in an\n\\emph{ensemble} of electronically isolated crystals in which system-bath\ninteractions are nevertheless strong. In this communication, we identify\nsignatures of Fano-like interference between excitons and photocarriers in the\ncoherent two-dimensional photoluminescence excitation spectral lineshapes of\nmixed lead-halide perovskite nanocrystals in dilute solution. Specifically, by\ntuning the femtosecond-pulse spectrum, we show such interference in an\nintermediate coupling regime, which is evident in the coherent lineshape when\nsimultaneously exciting the exciton and the free-carrier band at higher energy.\nWe conclude that this interference is an intrinsic effect that will be\nconsequential in the quantum dynamics of the system and will thus dictate\ndecoherence dynamics, with consequences in their application in quantum\ntechnologies.",
        "positive": "Polarization anisotropy in the optical properties of silicon ellipsoids: A new real space quantum mechanical approach with local field effects\nincluded is applied to the calculation of the optical properties of silicon\nnanocrystals. Silicon ellipsoids are studied and the role of surface\npolarization is discussed in details. In particular, surface polarization is\nshown to be responsible for a strong optical anisotropy in silicon ellipsoids,\nmuch more pronounced with respect to the case in which only quantum confinement\neffects are considered. The static dielectric constant and the absorption\nspectra are calculated, showing that the perpendicular and parallel components\nhave a very different dependence on the ellipsoid aspect ratio. Then, a\ncomparison with the classical dielectric model is performed, showing that the\nmodel only works for large and regular structures, but it fails for thin\nelongated ellipsoids."
    },
    {
        "anchor": "Atomic force microscopy study of the tetragonal to monoclinic\n  transformation behaviour of silica doped yttria-stabilized zirconia: The tetragonal to monoclinic phase transformation of zirconia has been the\nsubject of extensive studies over the last 20 years [1-4]. The main features of\nthe transformation have been identified and its martensitic nature is now\nwidely recognised [5-8]. More specifically, the relevance of a nucleation and\ngrowth model to describe the transformation is widely accepted. Recent fracture\nepisodes [9] of zirconia hip joint heads were reported, failures related to the\nt-m transformation degradation. Among the materials solutions considered for\ndecreasing the sensitivity to t-m phase transformation, the possibility of\nadding silica as a dopant appears as an appealing one. Previous studies have\nrevealed the beneficial effect of silica addition by the formation of a glassy\nphase at the grain boundaries and triple points. This glassy phase has been\nproven to reduce the residual stresses level [10], slowing down the\ntransformation kinetics. Preliminary quantitative investigations by XRD have\nshown these materials are less susceptible to transformation. However, the\nmechanism by which the transformation propagated has still to be assessed.",
        "positive": "AFLUX: The LUX materials search API for the AFLOW data repositories: Automated computational materials science frameworks rapidly generate large\nquantities of materials data useful for accelerated materials design. We have\nextended the data oriented AFLOW-repository API (Application-Program-Interface,\nas described in Comput. Mater. Sci. 93, 178 (2014)) to enable programmatic\naccess to search queries. A URI-based search API (Uniform Resource Identifier)\nis proposed for the construction of complex queries with the intent of allowing\nthe remote creation and retrieval of customized data sets. It is expected that\nthe new language AFLUX, acronym for Automatic Flow of LUX (light), will\nfacilitate the creation of remote search operations on the AFLOW.org set of\ncomputational materials science data repositories."
    },
    {
        "anchor": "Special quasirandom structure in heterovalent ionic systems: The use of a special quasirandom structure (SQS) is a rational and efficient\nway to approximate random alloys. A wide variety of physical properties of\nmetallic and semiconductor random alloys have been successfully estimated by a\ncombination of an SQS and density functional theory (DFT) calculation. Here, we\ninvestigate the application of an SQS to the ionic multicomponent systems with\nconfigurations of heterovalent ions, including point-charge lattices,\nMgAl$_2$O$_4$ and ZnSnP$_2$. It is found that the physical properties do not\nconverge with the supercell size of the SQS. This is ascribed to the fact that\nthe correlation functions of long-range clusters larger than the period of the\nsupercell are not optimized in the SQS. However, we demonstrate that the\nphysical properties of the perfectly disordered structure can be estimated by\nlinear extrapolation using the inverse of the supercell size.",
        "positive": "The microscopic origin of DMI in magnetic bilayers and prediction of\n  giant DMI in new bilayers: Skyrmions are widely regarded as promising candidates for emergent spintronic\ndevices. Dzyaloshinskii-Moriya interaction (DMI) is often critical to the\ngeneration and manipulation of skyrmions. However, there is a fundamental lack\nof understanding of the origin of DMI or the mechanism by which DMI generates\nskyrmions in magnetic bilayers. Very little is known of the material parameters\nthat determine the value of DMI. This knowledge is vital for rational design of\nskyrmion materials and further development of skyrmion technology. To address\nthis important problem, we investigate DMI in magnetic bilayers using\nfirst-principles. We present a new theoretical model that explains the\nmicroscopic origin of DMI in magnetic bilayers. We demonstrate that DMI depends\non two parameters, interfacial hybridization and orbital contributions of the\nheavy metal. Using these parameters, we explain the trend of DMI observed. We\nalso report four new materials systems with giant DMI and new designs for\nmagnetic multilayers that are expected to outperform the best materials known\nso far. Our results present a notably new understanding of DMI, uncover highly\npromising materials and put forth novel pathways for the controlled generation\nof skyrmions."
    },
    {
        "anchor": "Atomistic modeling of interfacial segregation and structural transitions\n  in ternary alloys: Grain boundary engineering via dopant segregation can dramatically change the\nproperties of a material. For metallic systems, most current studies concerning\ninterfacial segregation and subsequent transitions of grain boundary structure\nare limited to binary alloys, yet many important alloy systems contain more\nthan one type of dopant. In this work, hybrid Monte Carlo/molecular dynamics\nsimulations are performed to investigate the behavior of dopants at interfaces\nin two model ternary alloy systems: Cu-Zr-Ag and Al-Zr-Cu. Trends in boundary\nsegregation are studied, as well as the propensity for the grain boundary\nstructure to become disordered at high temperature and doping concentration.\nFor Al-Zr-Cu, we find that the two solutes prefer to occupy different sites at\nthe grain boundary, leading to a synergistic doping effect. Alternatively, for\nCu-Zr-Ag, there is site competition because the preferred segregation sites are\nthe same. Finally, we find that thicker amorphous intergranular films can be\nformed in ternary systems by controlling the concentration ratio of different\nsolute elements.",
        "positive": "Development of exchange-correlation functionals assisted by machine\n  learning: With the recent rapid progress in the machine-learning (ML), there have\nemerged a new approach using the ML methods to the exchange-correlation\nfunctional of density functional theory. In this chapter, we review how the ML\ntools are used for this and the performances achieved recently. It is revealed\nthat the ML, not being opposed to the analytical methods, complements the human\nintuition and advance the development toward the first-principles calculation\nwith desired accuracy."
    },
    {
        "anchor": "Anomalous phonon behavior of carbon nanotubes: First-order influence of\n  external load: External loads typically have a indirect influence on phonon curves, i.e.,\nthey influence the phonon curves by changing the state about which\nlinearization is performed. In this paper, we show that in nanotubes, the axial\nload has a direct first-order influence on the long-wavelength behavior of the\ntransverse acoustic (TA) mode. In particular, when the tube is force-free the\nTA mode frequencies vary quadratically with wave number and have curvature\n(second derivative) proportional to the square-root of the nanotube's bending\nstiffness. When the tube has non-zero external force, the TA mode frequencies\nvary linearly with wave number and have slope proportional to the square-root\nof the axial force. Therefore, the TA phonon curves -- and associated transport\nproperties -- are not material properties but rather can be directly tuned by\nexternal loads. In addition, we show that the out-of-plane shear deformation\ndoes {\\em not} contribute to this mode and the unusual properties of the TA\nmode are exclusively due to bending. Our calculations consist of 3 parts:\nfirst, we use a linear chain of atoms as an illustrative example that can be\nsolved in close-form; second, we use our recently-developed symmetry-adapted\nphonon analysis method to present direct numerical evidence; and finally, we\npresent a simple mechanical model that captures the essential physics of the\ngeometric nonlinearity in slender nanotubes that couples the axial load\ndirectly to the phonon curves. We also compute the Density of States and show\nthe significant effect of the external load.",
        "positive": "Heavy non-degenerate electrons in doped strontium titanate: Room-temperature metallicity of lightly doped SrTiO$_3$ is puzzling, because\nthe combination of mobility and the effective mass would imply a mean-free-path\n(mfp) below the Mott Ioffe Regel (MIR) limit and a scattering time shorter than\nthe Planckian time ($\\tau_P=\\hbar/k_BT$). We present a study of electric\nresistivity, Seebeck coefficient and inelastic neutron scattering extended to\nvery high temperatures, which deepens the puzzle. Metallic resistivity persists\nup to 900 K and is accompanied by a large Seebeck coefficient whose magnitude\n(as well as its temperature and doping dependence) indicates that carriers are\nbecoming heavier with rising temperature. Combining this with neutron\nscattering data, we find that between 500 K and 900 K, the Bohr radius and the\nelectron wave-length become comparable to each other and twice the lattice\nparameter. According to our results, between 100 K and 500 K, metallicity is\npartially driven by temperature-induced amplification of the carrier mass. We\ncontrast this mass amplification of non-degenerate electrons with the\nbetter-known case of heavy degenerate electrons. Above 500 K, the\nmean-free-path continues to shrink with warming in spite of becoming shorter\nthan both the interatomic distance and the thermal wavelength of the electrons.\nThe latter saturates to twice the lattice parameter. Available theories of\npolaronic quasi-particles do not provide satisfactory explanation for our\nobservations."
    },
    {
        "anchor": "A hard metallic material: Osmium Diboride: We calculate the structural and electronic properties of OsB2 using density\nfunctional theory with or without taking into account spin-orbit (SO)\ninteraction. Our results show that the bulk modulus with and without SO\ninteraction are 364 and 365 Gpa respectively, both are in good agreement with\nexperiment (365-395 Gpa). The evidence of covalent bonding of Os-B, which plays\nan important role to form a hard material, is indicated both in charge density,\natoms in molecules analysis, and density of states analysis. The good\nmetallicity and hardness of OsB2 might suggest its potential application as\nhard conductors.",
        "positive": "Monte Carlo Study of Magnetic Resistivity in Semiconducting MnTe: We investigate in this paper properties of the spin resistivity in the\nmagnetic semiconducting MnTe of NiAs structure. MnTe is a crossroad\nsemiconductor with a large band gap. It is an antiferromagnet with the N\\'eel\ntemperature around 310K. Due to this high N\\'eel temperature, there are many\napplications using its magnetic properties. The method we use here is the Monte\nCarlo simulation in which we take into account the interaction between\nitinerant spins and lattice Mn spins. Our results show a very good agreement\nwith experiments on the shape of the spin resistivity near the N\\'eel\ntemperature."
    },
    {
        "anchor": "New Mechanism for Electronic Energy Relaxation in Nanocrystals: The low-frequency vibrational spectrum of an isolated nanometer-scale solid\ndiffers dramatically from that of a bulk crystal, causing the decay of a\nlocalized electronic state by phonon emission to be inhibited. We show,\nhowever, that an electron can also interact with the rigid translational motion\nof a nanocrystal. The form of the coupling is dictated by the equivalence\nprinciple and is independent of the ordinary electron-phonon interaction. We\ncalculate the rate of nonradiative energy relaxation provided by this mechanism\nand establish its experimental observability.",
        "positive": "Stacking Domain Wall Magnons in Twisted van der Waals Magnets: Using bilayer CrI$_3$ as an example, we demonstrate that stacking domain\nwalls in van der Waals magnets can host one dimensional (1D) magnon channels,\nwhich have lower energies than bulk magnons. Interestingly, some magnon\nchannels are hidden in magnetically homogeneous background and can only be\ninferred with the knowledge of stacking domain walls. Compared to 1D magnons\nconfined in magnetic domain walls, 1D magnons in stacking domain walls are more\nstable against external perturbations. We show that the relaxed moir\\'e\nsuperlattices of small-angle twisted bilayer CrI$_3$ is a natural realization\nof stacking domain walls and host interconnected moir\\'e magnon network. Our\nwork reveals the importance of stacking domain walls in understanding magnetic\nproperties of van der Waals magnets, and extends the scope of stacking\nengineering to magnetic dynamics."
    },
    {
        "anchor": "Phase diagram of La_{5/8-y}Nd_{y}Ca_{3/8}MnO_3 manganites: We report a detailed study of the electric transport and magnetic properties\nof the LaNdCaMnO manganite system. Substitution of LaIII by smaller NdIII ions,\nreduces the mean ionic radius of the A site ion. We have studied samples in the\nentire range between rich La and rich Nd compounds. Results of DC magnetization\nand resistivity show that doping destabilize the FM character of the pure La\ncompound and triggers the formation of a phase separated state at intermediate\ndoping. We have also found evidence of a dynamical behaviour within the phase\nseparated state. A phase diagram is constructed, summarizing the effect of\nchemical substitution on the system.",
        "positive": "Comparative study of the catalytic growth of patterned carbon nanotube\n  films: Three different catalysts (Fe, Ni, Co nitrates dissolved in ethanol) were\npatterned on a SiO2/Si substrate and multi-wall carbon nanotubes were grown by\ncatalytic decomposition of acetylene. We compare the growth of the carbon\nnanostructures in the temperature range between 580C and 1000C. With our\nexperimental set-up the catalyst solutions of cobalt and nickel were found to\nbe less efficient than the one of iron. An optimal production of multi-wall\nnanotubes was observed at temperatures between 650C and 720C with the iron\nsolution as catalyst. We found a tendency towards thicker structures with\nhigher temperatures. Finally, we suggest a mechanism for the growth of these\ncarbon structures."
    },
    {
        "anchor": "Simulation of spin-polarized scanning tunneling spectroscopy on complex\n  magnetic surfaces: Case of a Cr monolayer on Ag(111): We propose a computationally efficient atom-superposition-based method for\nsimulating spin-polarized scanning tunneling spectroscopy (SP-STS) on complex\nmagnetic surfaces based on the sample and tip electronic structures obtained\nfrom first principles. We go beyond the commonly used local density of states\n(LDOS) approximation for the differential conductance, dI/dV. The capabilities\nof our approach are illustrated for a Cr monolayer on a Ag(111) surface in a\nnoncollinear magnetic state. We find evidence that the simulated tunneling\nspectra and magnetic asymmetries are sensitive to the tip electronic structure,\nand we analyze the contributing terms. Related to SP-STS experiments, we show a\nway to simulate two-dimensional differential conductance maps and qualitatively\ncorrect effective spin polarization maps on a constant current contour above a\nmagnetic surface.",
        "positive": "Piezoelectric properties of substitutionally doped $\u03b2$-Ga$_2$O$_3$: Modern semiconductor materials are increasingly used in multidisciplinary\nsystems demonstrating cross-interactions between mechanical strains and\nelectronic potentials, which gives rise to ubiquitous applications in high\nsensitivity, self-powered sensor devices. One of fundamental prerequisites for\nsuch semiconductor materials to exhibit piezoelectric properties is the\nnoncentrosymmetry of the crystal structures. $\\beta$-Ga$_2$O$_3$ has been an\nemerging compound semiconductor material due to its ultra-wide bandgap. However\nthe pristine $\\beta$-Ga$_2$O$_3$ has an inversion center, displaying no\npiezoelectric effect. This work discovered that substitutionally doped\n$\\beta$-Ga$_2$O$_3$ possesses piezoelectric property by using first principles\nmethod, while majority of previous research on its substitutional doping has\nbeen focusing on the purposes of increasing electrical conductivity and\nformation of the semiconductor heterojunctions. More interestingly, it is\nunveiled from this work that the formation energy has a clear relation with the\npiezoelectric coefficient."
    },
    {
        "anchor": "Optical 'Shorting Wires': Connecting lumped circuit elements in a conventional circuit is usually\naccomplished by conducting wires that act as conduits for the conduction\ncurrents with negligible potential drops. More challenging, however, is to\nextend these concepts to optical nanocircuit elements. Here, following our\nrecent development of optical lumped circuit elements, we show how a special\nclass of nanowaveguides formed by a thin core with relatively large (positive\nor negative) permittivity surrounded by a thin concentric shell with low\npermittivity may provide the required analogy to 'wires' for optical\nnano-circuits.",
        "positive": "The phonon drag force acting on a mobile crystal defect: full treatment\n  of discreteness and non-linearity: Phonon scattering calculations predict the drag force acting on defects and\ndislocations rises linearly with temperature, in direct contradiction with\nmolecular dynamics simulations that often finds the drag force to be\nindependent of temperature. Using the Mori-Zwanzig projection technique, with\nno recourse to elasticity or scattering theories, we derive a general Langevin\nequation for a crystal defect, with full treatment of discreteness and\nnon-linearity in the defect core. We obtain an analytical expression for the\ndrag force that is evaluated in molecular statics and molecular dynamics,\nextracting the force on a defect directly from the inter-atomic forces. Our\nresults show that a temperature independent drag force arises because\nvibrations in a discrete crystal are never independent of the defect motion, an\nimplicit assumption in any phonon-based approach. This effect remains even when\nthe Peierls barrier is effectively zero, invalidating qualitative explanations\ninvolving the radiation of phonons. We apply our methods to an interstitial\ndefect in tungsten and solitons in the Frenkel-Kontorova model, finding very\ngood agreement with trajectory-based estimations of the thermal drag force."
    },
    {
        "anchor": "Ab Initio studies of the atomic structure and electronic density of\n  states of pure and hydrogenated a-Si: We propose a method to simulate a-Si and a-Si:H using an ab initio approach\nbased on the Harris functional and thermally amorphisized periodically\ncontinued cells with at least 64 atoms, and calculate their radial distribution\nfunctions. Hydrogen incorporation was achieved via diffusive random addition.\nThe electronic density of states (DOS) is obtained using density functional\ntheory with the aid of both the Harris-functional and Kohn-Sham-LDA approaches.\nTwo time steps are used, 2.44 and 10 fs for the pure, and 0.46 and 2 fs for the\nhydrogenated, to see their effect on the topological and DOS structure of the\nsamples. The calculated long time-step radial features of a-Si are in very good\nagreement with experiment whereas for a-Si:H the short time-step partial and\ntotal radial features agree well; for the long time-step simulation molecular\nhydrogen appears during annealing.The long time-step a-Si has a well defined\ngap with two dangling bonds, that clears and increases upon hydrogen addition\nand relaxation, as expected. The short time-step structures have more defects,\nboth dangling and floating bonds, that are less characteristic of a good\nsample; however the radial structures of a-Si:H are in better agreement with\nexperiment indicating that the experimental work was done on defective samples.",
        "positive": "Imidazolium Ionic Liquid Mediates Black Phosphorus Exfoliation while\n  Preventing Phosphorene Decomposition: Forthcoming applications in electronics and optoelectronics make phosphorene\na subject of vigorous research efforts. Solvent-assisted exfoliation of\nphosphorene promises affordable delivery in industrial quantities for future\napplications. We demonstrate, using equilibrium, steered and umbrella sampling\nmolecular dynamics, that the 1-ethyl-3- methylimidazolium tetrafluoroborate\n[EMIM][BF4] ionic liquid is an excellent solvent for phosphorene exfoliation.\nThe presence of both hydrophobic and hydrophilic moieties, as well as\nsubstantial shear viscosity, allows [EMIM][BF4] simultaneously to facilitate\nseparation of phosphorene sheets and to protect them from getting in direct\ncontact with moisture and oxygen. The exfoliation thermodynamics is moderately\nunfavorable, indicating that an external stimulus is necessary. Unexpectedly,\n[EMIM][BF4] does not coordinates phosphorene by p-electron stacking with the\nimidazole ring. Instead, the solvation proceeds via hydrophobic side chains,\nwhile polar imidazole rings form an electrostatically stabilized protective\nlayer. The simulations suggest that further efforts in solvent engineering for\nphosphorene exfoliation should concentrate on use of weakly coordinating ions\nand grafting groups that promote stronger dispersion interactions, and on\nelongation of nonpolar chains."
    },
    {
        "anchor": "Giant Magnetoresistance in Multilayers with Noncollinear Magnetizations: We study the dependence of perpendicular-current magnetoresistance in\nmagnetic multilayers on the angle between the magnetizations of the layers.\nThis dependence varies with the thickness of one of the layers, and is\ndifferent for multilayers with two and three magnetic layers. We derive a\nsystem of equations representing an extension of the two-current series\nresistor model, and show that the angular dependence of magnetoresistance gives\ninformation about the noncollinear spin-transport in ferromagnets.",
        "positive": "pi-stacking in thiophene oligomers as the driving force for\n  electroactive materials and devices: The pi-stacking between aromatic oligomers has been extensively studied for\nmany years, although the notion of exploiting this phenomenon as the driving\nforce for molecular actuation has only recently emerged. In this work we\nexamine with MP2 and Car-Parrinello ab initio calculations the actuation\nproperties of a novel class of thiophene-based materials introduced by Swager\net al.(Adv. Mater. 14, 368 (2002); JACS 125, 1142 (2003)). The chemical\ningredients of the assembly, calix[4]arenes and oligothiophenes, are screened\nseparately to characterize the actuation mechanisms and design optimal\narchitectures. In particular, ab initio methods are used to study pi-stacking\nin mixed valence oligothiophene dimers, revealing strong interactions that can\nbe turned on and off as a function of the electrochemical potential. We show\nhow these interactions could be harnessed to achieve molecular actuation and\ninvestigate the response of an active unit in real time with first-principles\nmolecular dynamics simulations."
    },
    {
        "anchor": "Controlled Growth of Large-Area Bilayer Tungsten Diselenides with\n  Lateral P-N Junctions: Bilayer two-dimensional (2D) van der Waals (vdW) materials are attracting\nincreasing attention due to their predicted high quality electronic and optical\nproperties. Here we demonstrate dense, selective growth of WSe2 bilayer flakes\nby chemical vapor deposition with the use of a 1:10 molar mixture of sodium\ncholate and sodium chloride as the growth promoter to control the local\ndiffusion of W-containing species. A large fraction of the bilayer WSe2 flakes\nshowed a 0 and 60o twist between the two layers, while moire 15 and 30o-twist\nangles were also observed. Well-defined monolayer-bilayer junctions were formed\nin the as-grown bilayer WSe2 flakes, and these interfaces exhibited p-n diode\nrectification and an ambipolar transport characteristic. This work provides an\nefficient method for the layer-controlled growth of 2D materials, in\nparticular, 2D transition metal dichalcogenides and promotes their applications\nin next-generation electronic and optoelectronic devices.",
        "positive": "Charge carrier injection into insulating media: single-particle versus\n  mean-field approach: Self-consistent, mean-field description of charge injection into a dielectric\nmedium is modified to account for discreteness of charge carriers. The improved\nscheme includes both the Schottky barrier lowering due to the individual image\ncharge and the barrier change due to the field penetration into the injecting\nelectrode that ensures validity of the model at both high and low injection\nrates including the barrier dominated and the space-charge dominated regimes.\nComparison of the theory with experiment on an unipolar ITO/PPV/Au-device is\npresented."
    },
    {
        "anchor": "Microscopic mechanism of ultrashort-pulse laser ablation of metals: a\n  molecular dynamics study incorporating electronic entropy effects: The microscopic mechanism of metal ablation induced by ultrashort laser pulse\nirradiation is investigated. A two-temperature model scheme combined with\nmolecular dynamics (TTM-MD) is developed to incorporate electronic entropy\neffects into the simulation of metal ablation while satisfying the energy\nconservation law. Simulation with the TTM-MD scheme reveals that ultrashort\nlaser pulse irradiation near the ablation threshold causes high-energy ion\nemission and sub-nanometer depth ablation, as observed experimentally, due to\nthe electronic entropy effect. It is also shown that the electronic entropy\neffect is also significant in spallation.",
        "positive": "Computationally accelerated experimental materials characterization --\n  drawing inspiration from high-throughput simulation workflows: Computational materials science is increasingly benefitting from data\nmanagement, automation, and algorithm-based decision-making in controlling\nsimulations. Experimental materials science is also undergoing a change and\nincreasingly more `machine learning' is incorporated in materials discovery\ncampaigns. The obvious benefits include automation, reproducibility, data\nprovenance, and reusability of managed data, however, is not widely available.\nWe demonstrate an implementation of a Gaussian Process Regression directly\ncontrolling an experimental measurement device in pyiron, a framework designed\nfor high-throughput simulations, as a first step to increasingly combine\nexperimental and simulated data in one framework. With data from both in the\nsame framework, a heretofore untapped and much-needed potential for the\nacceleration of materials characterization and materials discovery campaigns\nbecomes available."
    },
    {
        "anchor": "The effect of the interface energy on pattern selection in alloy\n  solidification: A phase-field study: A thorough understanding of pattern selection is necessary for the control of\nsolidification structures, which are dissipative structures created by\nirreversible processes. In this paper, we simulate solidification evolution\nwith different Preferred Crystallographic Orientations (PCOs) through the\nPhase-Field model. Then we study the effect of solute segregation on the\ninterface energy, as well as the influence of the interface energy on the\npattern selection. At the initial stage, the solute segregation influences the\ninterface energy, determining the instability of the planar interface. During\nthe detailed evolution of the Planar-Cellular-Transition (PCT), the surface\nstiffness dominates this stage. At the PCT stage, high degree of solute\nsegregation refers to the low interface energy, resulting in the appearing of\nthe sidebranches behind the tip of the primary dendrites. At the steady-state\nstage, the overall propagation velocities of the interfaces are the same, while\nthe tip velocities are different in the simulations with different PCOs. The\ndifferent tip velocities give rise to the different morphological evolution of\nthe interfaces. The viewpoints of the whole dissipative system and the local\nfree energy are discussed, respectively. This paper demonstrates the effect of\nsolute segregation on the interface energy, as well as the influence of the\ninterface energy on the pattern selection.",
        "positive": "Effect of interface on epitaxy and magnetism in h-RFeO3/Fe3O4/Al2O3\n  films (R=Lu, Yb): We have carried out the growth of h-RFeO3 (001) (R=Lu, Yb) thin films on\nFe3O4 (111)/Al2O3 (001) substrates, and studied the effect of the h-RFeO3\n(001)/Fe3O4 (111) interfaces on the epitaxy and magnetism. The observed\nepitaxial relations between h-RFeO3 and Fe3O4 indicates an unusual matching of\nFe sub-lattices rather than a matching of O sub-lattices. The out-of-plane\ndirection was found to be the easy magnetic axis for h-YbFeO3 (001) but the\nhard axis for Fe3O4 (111) in the h-YbFeO3 (001)/Fe3O4 (111)/Al2O3 (001) films,\nsuggesting a perpendicular magnetic alignment at the h-YbFeO3 (001)/Fe3O4 (111)\ninterface. These results indicate that Fe3O4 (111)/Al2O3 (001) could be a\npromising substrate for epitaxial growth of h-RFeO3 films of well-defined\ninterface and for exploiting their spintronic properties."
    },
    {
        "anchor": "Ferroelectricity in multiferroic magnetite Fe3O4 driven by\n  noncentrosymmetric Fe2+/Fe3+ charge-ordering: First-principles study: By means of first-principles simulations, we unambiguously show that improper\nferroelectricity in magnetite in the low-temperature insulating phase is driven\nby charge-ordering. An accurate comparison between monoclinic ferroelectric Cc\nand paraelectric P2/c structures shows that the polarization arises because of\n\"shifts\" of electronic charge between octahedral Fe sites, leading to a\nnon-centrosymmetric Fe2+/Fe3+ charge-ordered pattern. Our predicted values for\npolarization, in good agreement with available experimental values, are\ndiscussed in terms of point-charge dipoles located on selected Fe tetrahedra,\npointing to a manifest example of electronic ferroelectricity driven by charge\nrearrangement.",
        "positive": "Charge transport in monolayers of metal nanoparticles: Two-dimensional (2D) nanoparticle films are a new class of materials with\ninteresting physical properties and applications ranging from nanoelectronics\nto sensing and photonics. The importance of conducting nanoparticle films makes\nthe fundamental understanding of their charge transport extremely important for\nmaterials and process design. Various hopping and transport mechanisms have\nbeen proposed and the nanoparticle monolayer is consistent with the electrical\nequivalent RC circuit, but their theoretical methods are limited to the model\nof the single electron tunneling between capacitively coupled nanoparticles\nwith a characteristic time constant RC and the conductivity of thin film is the\nexperimental conductivity, which cannot be deduced from these theoretical\nmodels. It is also unclear that how the specific process of electron transpot\nis affected by temperature. So, nowadays the electron dynamics of thin film\ncannot be understood fundamentally. Here, we develop an analytical theory based\non the model of Sommerfeld, backed up by Monte-Carlo simulations, that predicts\nthe process of charge transport and the effect of temperature on the electron\ntransport in the thin film. In this paper two different nanoparticle models\nwere built to cope with different types of morphology: triangular array and\nrectangular array. The transport properties of these different kinds of arrays\nincluding 2D ordered nanoparticle arrays with/without local structural disorder\nand 2D gradient nanoparticle arrays were investigated at different\ntemperatures. For 2D well-ordered nanoparticle array without local structural\ndisorder, the I-V curves are non-linear and highly symmetric."
    },
    {
        "anchor": "Graphitic nanofibres from electrospun solutions of PAN in\n  dimethylsulphoxide: Homogenous graphitic nanofibres (GNFs) have been synthesised by heat\ntreatment of electrospun polyacrylonitrile in dimethylsulphoxide, offering a\nnew solution route of low toxicity to manufacture sub-60 nm diameter GNFs.\nFibre beading resulting from the spinning of low-concentration polymer\nsolutions can be reduced with the addition of surfactant or sodium chloride.\nCharacterisation techniques including X-ray diffraction, scanning- and\ntransmission electron microscopy have been used to quantify the effect of the\ngraphitisation process, by heat treatment up to 3000 deg. C, on the weight,\ndiameter and structural morphology of the nanofibres. The GNFs have an\nentangled micro-fibril structure with graphitic ordering of up to 40 graphene\nlayers after treatment at 3000 deg. C. There is little difference in the degree\nof graphitisation of GNFs prepared with a 250 deg. C oxidation step compared\nwith those prepared without, but oxidised GNFs retain more of their original\nmass after heating under argon flow.",
        "positive": "Defects of the Crystal Structure and Jahn-Teller distortion in BiMnO3: Using density-functional theory with the on-site Coulomb correction (the\nLDA+U method), we perform the structural optimization of BiMnO3 by starting\nfrom different experimentally reported structures. We confirm that\nirrespectively on the starting condition, all calculations converge to the same\ncentrosymmetric structure, in agreement with the previous finding.\nNevertheless, the structural optimization substantially reduces the Jahn-Teller\n(JT) distortion in the system. We attribute this fact to the strong competition\nof local distortions around the Mn- and Bi-sites: while the local\nMn-environment experiences the JT instability, the one of the Bi-sites favours\nthe off-centrosymmetric displacements, which involves the same oxygen atoms.\nThe existence of the second mechanism explains the difference between BiMnO3\nand more canonical JT manganites, such as LaMnO3. Finally, being motivated by\nexperimental studies, we have investigated the formation of different types of\ndefects and obtained that BiMnO3 (contrary to other considered systems, such as\nLaMnO3 and BiFeO3) can relatively easily form oxygen impurities at interstitial\nsites. The impurity oxygen atom tends to form a pair with the host oxygen,\nwhich explains the insulating character of the oxygen-excessive BiMnO3+x.\nMoreover, we found that the BiMnO3+x samples experience the \"memory effect\",\nwhere the optimized crystal structure strongly depends on the starting\nconfiguration. We suggest that such a memory effect may explain stability of\nsome of the crystal structures of BiMnO3, which have been previously reported\nexperimentally."
    },
    {
        "anchor": "Spin amplitude modulation driven magnetoelectic coupling in the new\n  multiferroic FeTe$_2$O$_5$Br: Magnetic and ferroelectric properties of layered geometrically frustrated\ncluster compound FeTe$_2$O$_5$Br were investigated with single-crystal neutron\ndiffraction and dielectric measurements. Incommensurate amplitude modulated\nmagnetic order with the wave vector $\\bf{q}$=($\\half$, 0.463, 0) develops below\n$T_N=10.6(2) {\\rm K}$. Simultaneously, a ferroelectric order with the\nspontaneous polarization perpendicular to ${\\bf q}$ and to Fe$^{3+}$ magnetic\nmoments emerges. The observed ferroelectricity and extraordinary linear scaling\nof the ferroelectric and magnetic order parameter are provoked by the striction\nof the intercluster Fe-O-Te-O-Fe bridges leading to the shift of Te$^{4+}$ ions\nand polarization of their lone-pair electrons.",
        "positive": "Dynamics of Li-ion in V2O5 Layers from First-Principles Calculations: The alkali atoms, due to their small sizes and low charge ionic states, are\nmost eligible to intercalate in the structural layers of V2O5. We have applied\nab-initio density functional theory to study the dynamics of Li-ion in layers\nof {\\alpha}-V2O5. The calculations are performed for two compositions, namely,\nLi0.08V2O5 and Li0.16V2O5, and show that there are unstable phonon frequencies.\nThe unstable modes have large amplitude of Li atom along the b-axis of the\northorhombic unit cell indicating that such unstable modes could initiate\nLi-ion diffusion along b-axis. The ab-initio molecular dynamics simulations are\nperformed up to 25 ps at 1200 K, which reveal one-dimensional diffusion of Li\natoms. The diffusion pathways of Li atoms from the simulations seem to follow\nthe eigenvectors of the unstable phonon modes obtained in the intercalated\nstructure."
    },
    {
        "anchor": "Magnetic-dipolar and electromagnetic vortices in quasi-2D ferrite disks: Magnetic-dipolar-mode (MDM) oscillations in a quasi-2D ferrite disk show\nunique dynamical symmetry properties resulting in appearance of topologically\ndistinct structures. Based on the magnetostatic (MS) spectral problem\nsolutions, in this paper we give an evidence for eigen MS power-flow-density\nvortices in a ferrite disk. Due to these circular eigen power flows, the MDMs\nare characterized by MS energy eigen states. It becomes evident that the reason\nof stability of the vortex configurations in saturated ferrite samples is\ncompletely different from the nature of stability in magnetically soft\ncylindrical dots. We found a clear correspondence between analytically derived\nMDM vortex states and numerically modeled electromagnetic vortices in quasi-2D\nferrite disks.",
        "positive": "Phase stability and physical properties of hypothetical V4SiC3: We study the phase stability, mechanical, electronic, optical properties and\nVicker's hardness of the newly predicted layered compound V4SiC3 using the\nfirst-principles method. This hypothetical compound is found to possess higher\nbulk modulus as well as higher hardness than those of a similar V4AlC3. The\nMulliken bond population analysis indicates that the substitution of Al atom\nwith the Si atom increases the Vicker's hardness of this compound. The\nelectronic band structure shows that the conductivity is metallic and the main\ncontribution comes from V 3d states. The partial density of states (PDOS) shows\nthat the hybridization peak of V 3d and C 2s lies lower in energy than that of\nV 3d and Si 3p states which suggests that the V 3d - C 2s bond is stronger than\nthe V 3d - Si 3p bond. The results are consistent with our bond analysis.\nFurther we have discussed the origin of the features that appear in the optical\nproperties. V4SiC3 is seen as a promising dielectric material showing a much\nbetter candidate material as a coating to avoid solar heating than those of\nV4AlC3, {\\alpha}-Nb4SiC3 and Ti4AlN3 compounds.\n  Keywords: MAX phase V4SiC3; Phase stability; Electronic properties; Optical\nproperties; Vicker's hardness.\n  PACS: 61.66.Fn, 62.20.-x, 62.20.Dc, 71.15Mb, 78.20.Ci"
    },
    {
        "anchor": "Atomistic graph networks for experimental materials property prediction: Machine Learning (ML) has the potential to accelerate discovery of new\nmaterials and shed light on useful properties of existing materials. A key\ndifficulty when applying ML in Materials Science is that experimental datasets\nof material properties tend to be small. In this work we show how material\ndescriptors can be learned from the structures present in large scale datasets\nof material simulations; and how these descriptors can be used to improve the\nprediction of an experimental property, the energy of formation of a solid. The\nmaterial descriptors are learned by training a Graph Neural Network to regress\nsimulated formation energies from a material's atomistic structure. Using these\nlearned features for experimental property predictions outperforms existing\nmethods that are based solely on chemical composition. Moreover, we find that\nthe advantage of our approach increases as the generalization requirements of\nthe task are made more stringent, for example when limiting the amount of\ntraining data or when generalizing to unseen chemical spaces.",
        "positive": "Real-Time Observation of Self-Interstitial Reactions on an Atomically\n  Smooth Silicon Surface: Self-diffusion and impurity diffusion both play crucial roles in the\nfabrication of semiconductor nanostructures with high surface-to-volume ratios.\nHowever, experimental studies of bulk-surface reactions of point defects in\nsemiconductors are strongly hampered by extremely low concentrations and\ndifficulties in the visualization of single point defects in the crystal\nlattice. Herein we report the first real-time experimental observation of the\nself-interstitial reactions on a large atomically smooth silicon surface. We\nshow that non-equilibrium self-interstitials generated in silicon bulk during\ngold diffusion in the temperature range 860-1000^oC are annihilated at the\n(111) surface, producing the net mass flux of silicon from the bulk to the\nsurface. The kinetics of the two-dimensional islands formed by\nself-interstitials are dominated by the reactions at the atomic step edges. The\nactivation energy for the interaction of self-interstitials with the surface\nand energy barrier for gold penetration into the silicon bulk through the\nsurface are estimated. These results demonstrating that surface morphology can\nbe profoundly affected by surface-bulk reactions should have important\nimplications for the development of nanoscale fabrication techniques."
    },
    {
        "anchor": "The Effects of Vacancy and Oxidation on Black Phosphorus Nanoresonators: Black phosphorene is not stable at ambient conditions, so atomic defects and\noxidation effects are unavoidable in black phosphorus samples in the\nexperiment. The effects of these defects on the performance of the black\nphosphorus nanoresonators are still unclear. Here, we perform classical\nmolecular dynamics to investigate the effects of the vacancy and oxidation on\nsingle-layer black phosphorus nanoresonators at different temperatures. We find\nthat the vacancy causes strong reduction in the quality factor of the\nnanoresonators, while the oxidation has weaker effect on the nanoresonators.\nMore specifically, a 2% concentration of randomly distributed single vacancies\nis able to reduce the quality factor by about 80% and 40% at 4.2K and 50K,\nrespectively. We also find that the quality factor of the nanoresonator is not\nsensitive to the distribution pattern of the vacancy defects.",
        "positive": "Powder reuse cycles in electron beam powder bed fusion : Variation of\n  powder characteristics: A path to lowering the economic barrier associated with the high cost of\nmetal additively manufactured components is to reduce the waste via powder\nreuse (powder cycled back into the process) and recycling (powder chemically,\nphysically, or thermally processed to recover the original properties)\nstrategies. In electron beam powder bed fusion, there is a possibility of\nreusing 95 - 98% of the powder that is not melted. However, there is a lack of\nsystematic studies focusing on quantifying the variation of powder properties\ninduced by number of reuse cycles. This work compares the influence of multiple\nreuse cycles, as well as powder blends created from reused powder, on various\npowder characteristics such as the morphology, size distribution, flow\nproperties, packing properties and chemical composition (oxygen and nitrogen\ncontent). It was found that there is an increase in measured response in powder\nsize distribution, tapped density, Hausner ratio, Carr index, basic flow energy\nand specific energy, dynamic angle of repose, oxygen, and nitrogen content,\nwhile the bulk density remained largely unchanged."
    },
    {
        "anchor": "Optical properties of structurally-relaxed Si/SiO$_2$ superlattices: the\n  role of bonding at interfaces: We have constructed microscopic, structurally-relaxed atomistic models of\nSi/SiO$_2$ superlattices. The structural distortion and oxidation-state\ncharacteristics of the interface Si atoms are examined in detail. The role\nplayed by the interface Si suboxides in raising the band gap and producing\ndispersionless energy bands is established. The suboxide atoms are shown to\ngenerate an abrupt interface layer about 1.60 \\AA thick. Bandstructure and\noptical-absorption calculations at the Fermi Golden rule level are used to\ndemonstrate that increasing confinement leads to (a) direct bandgaps (b) a blue\nshift in the spectrum, and (c) an enhancement of the absorption intensity in\nthe threshold-energy region. Some aspects of this behaviour appear not only in\nthe symmetry direction associated with the superlattice axis, but also in the\northogonal plane directions. We conclude that, in contrast to Si/Ge, Si/SiO$_2$\nsuperlattices show clear optical enhancement and a shift of the optical\nspectrum into the region useful for many opto-electronic applications.",
        "positive": "Effect of the metallicity on the capacitance of gold - aqueous sodium\n  chloride interfaces: Electrochemistry experiments have established that the capacitance of\nelectrode-electrolyte interfaces is much larger for good metals such as gold\nand platinum than for carbon-based materials. Despite the development of\nelaborate electrode interaction potentials, to date molecular dynamics\nsimulations were not able to capture this effect. Here we show that changing\nthe width of the Gaussian charge distribution used to represent the atomic\ncharges in gold is an effective way to tune its metallicity. Larger Gaussian\nwidths lead to a capacitance of aqueous solutions (pure water and 1 molar NaCl)\nin good agreement with recent ab initio molecular dynamics results. For pure\nwater, the increase in the capacitance is not accompanied with structural\nchanges, while in the presence of salt the Na$^+$ cations tend to adsorb\nsignificantly on the surface. For a strongly metallic gold electrode, these\nions can even form inner sphere complexes on hollow sites of the surface."
    },
    {
        "anchor": "High-throughput calculations combining machine learning to investigate\n  the corrosion properties of binary Mg alloys: Magnesium (Mg) alloys have shown great prospects as both structural and\nbiomedical materials, while poor corrosion resistance limits their further\napplication. In this work, to avoid the time-consuming and laborious experiment\ntrial, a high-throughput computational strategy based on first-principles\ncalculations is designed for screening corrosion-resistant binary Mg alloy with\nintermetallics, from both the thermodynamic and kinetic perspectives. The\nstable binary Mg intermetallics with low equilibrium potential difference with\nrespect to the Mg matrix are firstly identified. Then, the hydrogen adsorption\nenergies on the surfaces of these Mg intermetallics are calculated, and the\ncorrosion exchange current density is further calculated by a hydrogen\nevolution reaction (HER) kinetic model. Several intermetallics, e.g. Y3Mg, Y2Mg\nand La5Mg, are identified to be promising intermetallics which might\neffectively hinder the cathodic HER. Furthermore, machine learning (ML) models\nare developed to predict Mg intermetallics with proper hydrogen adsorption\nenergy employing work function (W_f) and weighted first ionization energy\n(WFIE). The generalization of the ML models is tested on five new binary Mg\nintermetallics with the average root mean square error (RMSE) of 0.11 eV. This\nstudy not only predicts some promising binary Mg intermetallics which may\nsuppress the galvanic corrosion, but also provides a high-throughput screening\nstrategy and ML models for the design of corrosion-resistant alloy, which can\nbe extended to ternary Mg alloys or other alloy systems.",
        "positive": "Monolithic integration of 940 nm AlGaAs distributed Bragg reflectors on\n  bulk Ge substrates: High quality 940 nm Al$_x$Ga$_{1-x}$As n-type distributed Bragg reflectors\n(DBRs) were successfully monolithically grown on off-cut Ge (100) substrates.\nThe Ge-DBRs have reflectivity spectra comparable to those grown on conventional\nbulk GaAs substrates and have smooth morphology, reasonable periodicity and\nuniformity. These results strongly support VCSEL growth and fabrication on more\nscalable bulk Ge substrates for large scale production of AlGaAs-based VCSELs."
    },
    {
        "anchor": "Effect of inorganic cation mixing on hybrid halide perovskites using\n  density functional theory for application in single and multi junction\n  photovoltaics: This work is aimed to study mixed-cation (hybrid methyl ammonium plus\ninorganic cations) halide perovskites using first principles Density Functional\nTheory (DFT) formalism in order to find their potential applications in\nperovskite based photovoltaics. This is an addition to the two previous studies\nperformed by the author on high-throughput screening of hybrid halide and\ninorganic halide perovskites. This work involves mixing certain amounts of the\ninorganic cation to the organic site (methyl ammonium) and study the electronic\nstructure of the resultant. 63 perovskites have been simulated in their\ncalculated stable phases and their band gaps have been predicted. Band gaps are\nimportant parameters to predict as these indicate their potential to be used as\nopto-electronic devices. From the calculated band gaps, 37 perovskites are\npredicted to be suitable for single junction as well as multi junction solar\ncell application, 7 are not suitable for either single or multi junction solar\ncells, and the rest 21 are suitable for multi junction but not for single\njunction solar cells. The study also shows interesting transition in the nature\nof the band gaps from indirect to direct and vice-versa caused at about 50% of\ninorganic cation mixing.",
        "positive": "Ultraviolet-ozone treatment: an effective method for fine-tuning optical\n  and electrical properties of suspended and substrate-supported MoS2: Ultraviolet-ozone (UV-O3) treatment is a simple but effective technique for\nsurface cleaning, surface sterilization, doping and oxidation, and is\napplicable to a wide range of materials. In this study, we investigated how\nUV-O3 treatment affects the optical and electrical properties of molybdenum\ndisulfide (MoS2), with and without the presence of a dielectric substrate. We\nperformed detailed photoluminescence (PL) measurements on 1-7 layers of MoS2\nwith up to 8 minutes of UV-O3 exposure. Density functional theory (DFT)\ncalculations were carried out to provide insight into oxygen-MoS2 interaction\nmechanisms. Our results showed that the influence of UV-O3 treatment on PL\ndepends on whether the substrate is present, as well as the number of layers.\nThe PL intensity of the substrate-supported MoS2 decreased dramatically with\nthe increase of UV-O3 treatment time and was fully quenched after 8 mins.\nHowever, the PL intensity of the suspended flakes was less affected. 4 minutes\nof UV-O3 exposure was found to be optimal to produce p-type MoS2, while\nmaintaining above 80% of the PL intensity and the emission wavelength, compared\nto pristine flakes (intrinsically n-type). Our electrical measurements showed\nthat UV-O3 treatment for more than 6 minutes not only caused a reduction in the\nelectron density but also deteriorated the hole-dominated transport. It is\nrevealed that the substrate plays a critical role in the manipulation of the\nelectrical and optical properties of MoS2, which should be considered in future\ndevice fabrication and applications."
    },
    {
        "anchor": "Oxygen-dislocation interaction in titanium from first principles: The interaction between screw dislocations and oxygen interstitial atoms is\nstudied with ab initio calculations in hexagonal close-packed titanium. Our\ncalculations evidence a strong repulsion when the solute atoms are located in\nthe dislocation glide plane, leading to spontaneous cross-slip, which allows\nthe dislocation to bypass the atomic obstacle. This avoidance process explains\nseveral experimental observations in titanium in presence of oxygen: (1) a\nlarger lattice friction against screw dislocation motion, (2) a reduction of\nthe dislocation glide distance in prismatic planes and (3) an enhancement of\ncross-slip in pyramidal planes.",
        "positive": "Effects of thermal treatment on radiative properties of HVPE grown InP\n  layers: Radiative efficiency of highly luminescent bulk InP wafers severely degrades\nupon heat treatment involved in epitaxial growth of quaternary layers and\nfabrication of photodiodes on the surface. This unfortunate property impedes\nthe use of bulk InP as scintillator material. On the other hand, it is known\nthat thin epitaxial InP layers, grown by molecular beam epitaxy (MBE) or\nmetal-organic chemical vapor deposition (MOCVD), do not exhibit any\ndegradation. These layers, however, are too thin to be useful in scintillators.\nThe capability of hydride vapor phase epitaxy (HVPE) process to grow thick\nbulk-like layers in reasonable time is well known, but the radiative properties\nof HVPE InP layers are not known. We have studied radiative properties of 21\nmicron thick InP layers grown by HVPE and found them comparable to those of\nbest luminescent bulk InP virgin wafers. In contrast to the bulk wafers, the\nradiative efficiency of HVPE layers does not degrade upon heat treatment. This\nopens up the possibility of implementing free-standing epitaxial InP\nscintillator structures endowed with surface photodiodes for registration of\nthe scintillation."
    },
    {
        "anchor": "Electronic-enthalpy functional for finite systems under pressure: We introduce the notion of electronic enthalpy for first-principles\nstructural and dynamical calculations of finite systems under pressure. An\nexternal pressure field is allowed to act directly on the electronic structure\nof the system studied via the ground-state minimization of the functional\n$E+PV_{q}$, where $V_{q}$ is the quantum volume enclosed by a charge\nisosurface. The Hellmann-Feynman theorem applies, and assures that the ionic\nequations of motion follow an isoenthalpic dynamics. No pressurizing medium is\nexplicitly required, while coatings of environmental ions or ligands can be\nintroduced if chemically relevant. We apply this novel approach to the study of\ngroup-IV nanoparticles during a shock wave, highlighting the significant\ndifferences inthe plastic or elastic response of the diamond cage under load,\nand their potential use as novel nanostructured impact-absorbing materials.",
        "positive": "Ab-initio studies on the phonons of BaTiO3 polytypes: pressure\n  dependences with a hybrid functional: We report the first principles investigations on the phonons of three\npolytypes of BaTiO3 (BTO): paraelectric (PE) cubic Pm-3m and two ferroelectric\n(FE) phases, tetragonal P4mm and rhombohedral R3m. The phonon frequencies\ncalculated using various exchange-correlation functionals, including density\nfunctional theory, Hartree-Fock approximation, and their hybrids were reviewed.\nThe pressure-induced interplays between the modes form individual phases were\nexplored by calculating the phonon modes as a function of pressure, P from -15\nto 230 GPa. The pressure-sensitive modes of the FE phases showed softening and\nconverged to the modes of the PE phase at pressures below ~ 10 GPa. These\nresults on the FE phases can be interpreted as phonon-precursors for a change\nin symmetry from low- to high-symmetry and partly as a theoretical explanation\nfor the pressure-induced mode-coupling behaviors reported by Sood et al. [Phys.\nRev. B 51, 8892 (1995)]. As pressure is applied further beyond ~ 50 GPa to the\ncubic PE phase, the lowest F1u mode softens again and diverges into two\nseparate modes of tetragonal FE P4mm at above ~ 150 GPa. These phonon-branching\nbehaviors at high pressures provide a clear re-confirmation of the re-entrant\nferroelectricity predicted in [Phys. Rev. Lett. 95, 196804 (2005); Phys. Rev. B\n74, 180101 (2006); ibid. 85, 054108 (2012)]. The high-pressure-re-entrant FE\npolarization was not found in the rhombohedral structure. Instead, the\ncentosymmetric R-3m phase was favored at above ~ 30 GPa. The phonon modes\ncalculated for the phonon-propagation vectors in the high-symmetry directions\nshow that the Pm-3m phase exhibits polar instability at the \\Gamma point and\nnon-polar instability at the X, M, and R points under high pressure."
    },
    {
        "anchor": "Whirling spin order in the quasicrystal approximant\n  Au$_{72}$Al$_{14}$Tb$_{14}$: Neutron powder diffraction experiment has been performed on the quasicrystal\napproximant Au$_{72}$Al$_{14}$Tb$_{14}$, a body-center-cubic crystal of\nicosahedral spin clusters. The long-range antiferromagnetic order was confirmed\nat the transition temperature $T_{\\rm N} = 10.4$ K. The magnetic structure\nconsists of noncoplanar whirling spins on the icosahedral clusters, arranging\nantiferroic-manner. A simple icosahedral spin-cluster model with uniaxial\nanisotropy accounts well the whirling spin order as well as the in-field\nmetamagnetic transition, indicating that the icosahedral symmetry is essential.",
        "positive": "Analyser-free, intensity-based wide-field magneto-optical microscopy: In conventional Kerr- and Faraday microscopy the sample is illuminated with\nplane-polarised light and a magnetic domain contrast is generated by an\nanalyser making use of the Kerr- or Faraday rotation. In this paper we\ndemonstrate possibilities of analyser-free magneto-optical microscopy based on\nmagnetisation-dependent intensity modulations of the light: (i) The transverse\nKerr effect can be applied for in-plane magnetised material, demonstrated for\nan FeSi sheet. (ii) Illuminating the same sample with circularly polarised\nlight leads to a domain contrast with a different symmetry as the conventional\nKerr contrast. (iii) Circular polarisation can also be used for perpendicularly\nmagnetised material, demonstrated for a garnet film and an ultrathin CoFeB\nfilm. (iv) Plane-polarised light at a specific angle can be employed for both,\nin-plane and perpendicular media. (v) Perpendicular light incidence leads to a\ndomain contrast on in-plane materials that is quadratic in the magnetisation\nand to a domain boundary contrast. (vi) Domain contrast can even be obtained\nwithout polariser. In cases (ii) and (iii), the contrast is generated by MCD\n(Magnetic Circular Dichroism), while MLD (Magnetic Linear Dichroism) is\nresponsible for the contrast in case (v). The domain boundary contrast is due\nto the magneto-optical gradient effect in metallic samples. A domain boundary\ncontrast can also arise due to interference of phase-shifted magneto-optical\namplitudes. An explanation of these contrast phenomena is provided in terms of\nMaxwell-Fresnel theory."
    },
    {
        "anchor": "Comparative study of Mo2Ga2C with superconducting MAX phase Mo2GaC: a\n  first-principles calculations: The structural, electronic, optical and thermodynamic properties of Mo2Ga2C\nare investigated using density functional theory (DFT) within the generalized\ngradient approximation (GGA). The optimized crystal structure is obtained and\nthe lattice parameters are compared with available experimental data. The\nelectronic density of states (DOS) is calculated and analyzed. The metallic\nbehavior for the compound is confirmed and the value of DOS at Fermi level is\n4.2 states per unit cell per eV. Technologically important optical parameters\n(e.g., dielectric function, refractive index, absorption coefficient, photo\nconductivity, reflectivity, and loss function) have been calculated for the\nfirst time. The study of dielectric constant (e1) indicates the Drude-like\nbehavior. The absorption and conductivity spectra suggest that the compound is\nmetallic. The reflectance spectrum shows that this compound has the potential\nto be used as a solar reflector. The thermodynamic properties such as the\ntemperature and pressure dependent bulk modulus, Debye temperature, specific\nheats, and thermal expansion coefficient of Mo2Ga2C MAX phase are derived from\nthe quasi-harmonic Debye model with phononic effect also for the first time.\nAnalysis of Tc expression using available parameter values (DOS, Debye\ntemperature, atomic mass etc.) suggests that the compound is less likely to be\nsuperconductor.",
        "positive": "Contact-Induced Semiconductor-to-Metal Transition in Single-Layer WS$_2$: Low-resistance ohmic contacts are a challenge for electronic devices based on\ntwo-dimensional materials. We show that an atomically precise junction between\na two-dimensional semiconductor and a metallic contact can lead to a\nsemiconductor-to-metal transition in the two-dimensional material--a finding\nwhich points the way to a possible method of achieving low-resistance\njunctions. Specifically, single-layer WS$_2$ undergoes a semiconductor-to-metal\ntransition when epitaxially grown on Ag(111), while it remains a direct band\ngap semiconductor on Au(111). The metallicity of the single layer on Ag(111) is\nestablished by lineshape analysis of core level photoemission spectra.\nAngle-resolved photoemission spectroscopy locates the metallic states near the\nQ point of the WS$_2$ Brillouin zone. Density functional theory calculations\nshow that the metallic states arise from hybridization between Ag bulk bands\nand the local conduction band minimum of WS$_2$ near the Q point."
    },
    {
        "anchor": "Phase field modeling of crack propagation under combined shear and\n  tensile loading with hybrid formulation: The crack phase field model has been well established and validated for a\nvariety of complex crack propagation patterns within a homogeneous medium under\neither tensile or shear loading. However, relatively less attention has been\npaid to crack propagation under combined tensile and shear loading or crack\npropagation within composite materials made of two constituents with very\ndifferent elastic moduli. In this work, we compare crack propagation under such\ncircumstances modelled by two representative formulations, anisotropic and\nhybrid formulations, which have distinct stiffness degradation schemes upon\ncrack propagation. We demonstrate that the hybrid formulation is more adequate\nfor modeling crack propagation problems under combined loading because the\nresidual stiffness of the damaged zone in the anisotropic formulation may lead\nto spurious crack growth and altered load-displacement response.",
        "positive": "Anomalous CDW ground state in Cu$_2$Se: a wave-like fluctuation of\n  $\\it{dc}$ I-V curve near 50 K: A charge density wave (CDW) ground state is observed in polycrystalline\nCu$_2$Se below 125 K, which corresponds to an energy gap of 40.9 meV and an\nelectron-phonon coupling constant of 0.6. Due to the polycrystalline structure,\nthe Peierls transition process has been expanded to a wide temperature range\nfrom 90 to 160 K. The Hall carrier concentration shows a continuous decrease\nfrom 2.1$\\times$10$^{20}$ to 1.6$\\times$10$^{20}$ cm$^{-3}$ in the temperature\nrange from 160 K to 80 K, while almost unchanged above 160 K and below 90 K.\nAfter entering the CDW ground state, a wave-like fluctuation was observed in\nthe I-V curve near 50 K, which exhibits as a periodic negative differential\nresistivity in an applied electric field due to the current. We also\ninvestigated the doping effect of Zn, Ni, and Te on the CDW ground state. Both\nZn and Ni doped Cu$_2$Se show a CDW character with increased energy gap and\nelectron-phonon coupling constant, but no notable Peierls transition was\nobserved in Te doped Cu$_2$Se. Similar wave-like I-V curve was also seen in\nCu$_{1.98}$Zn$_{0.02}$Se near 40 K. The regular fluctuation in $\\it{dc}$ I-V\ncurve was not magnetic field sensitive, but temperature and sample size\nsensitive."
    },
    {
        "anchor": "Fingerprinting quantum emitters in hexagonal boron nitride using strain: Two dimensional van der Waals crystals and their heterostructures provide an\nexciting alternative to bulk wide bandgap semiconductors as hosts of single\nphoton emitters. Amongst different layered materials, bright and robust\ndefect-based single photon emitters have been observed within hexagonal boron\nnitride, a layered wide-bandgap semiconductor. Despite research efforts to\ndate, the identities of the deep defects responsible for quantum emissions in\nhexagonal boron nitride remain unknown. In this theoretical work, I demonstrate\nthat the strain-induced changes in emission frequencies depend on: (i) the\ndetailed nature of the defect states involved in the optical excitations, and\n(ii) the rich boron chemistry that results in complex interactions between\nboron atoms. As each defect shows a distinct response to the strain, it can be\nused not only to tune emission frequencies, but also to identify the quantum\nemitters in hexagonal boron nitride.",
        "positive": "The impact of charge compensated and uncompensated strontium defects on\n  the stabilization of the ferroelectric phase in HfO$_2$: Different dopants with their specific dopant concentration can be utilized to\nproduce ferroelectric HfO$_2$ thin films. In this work it is explored for the\nexample of Sr in a comprehensive first-principles study. Density functional\ncalculations reveal structure, formation energy and total energy of the Sr\nrelated defects in HfO$_2$. We found the charge compensated defect including an\nassociated oxygen vacancy Sr$_\\text{Hf}$V$_\\text{O}$ to strongly favour the\nnon-ferroelectric, tetragonal P4$_\\text{2}$/mnc phase energetically. In\ncontrast, the uncompensated defect without oxygen vacancy Sr$_\\text{Hf}$\nfavours the ferroelectric, orthorhombic Pca2$_\\text{1}$ phase. According to the\nformation energy the uncompensated defect can form easily under oxygen rich\nconditions in the production process. Low oxygen partial pressure existing over\nthe lifetime promotes the loss of oxygen leading to V$_\\text{O}$ and, thus, the\ndestabilization of the ferroelectric, orthorhombic Pca2$_\\text{1}$ phase\naccompanied by an increase of the leakage current. This study attempts to\nfundamentally explain the stabilization of the ferroelectric, orthorhombic\nPca2$_\\text{1}$ phase by doping."
    },
    {
        "anchor": "From Monomers to Self-Assembled Monolayers: The Evolution of Molecular\n  Mobility with Structural Confinements: The effect of structural constriction on molecular mobility is investigated\nby broadband dielectric spectroscopy (BDS) within three types of molecular\narrangements: monomers, oligomers and self-assembled monolayers (SAMs). While\ndisordered monomers exhibit a variety of cooperative and local relaxation\nprocesses, the constrained nanodomains of oligomers and highly ordered\nstructure of monolayers exhibit much hindered local molecular fluctuations.\nParticularly, in SAMs, motions of the silane headgroups are totally prevented\nwhereas the polar endgroups forming the monolayer canopy show only one\ncooperative relaxation process. This latter molecular fluctuation is, for the\nfirst time, observed independently from other overlapping dielectric signals.\nNumerous electrostatic interactions among those dipolar endgroups are\nresponsible for the strong cooperativity and heterogeneity of the canopy\nrelaxation process. Our data analyses also revealed that the bulkiness of\ndipolar endgroups can disrupt the organization of the monolayer canopy thus\nincreasing their ability to fluctuate as temperature is increased.",
        "positive": "Switching of magnetism via modifying phase shift of quantum-well states\n  by tailoring the interface electronic structure: We demonstrate control of the magnetism of Pd(100) ultrathin films, which\nshow d-electron quantum-well induced ferromagnetism, via modulation of the\ninterface electronic state using density functional calculation. From an\nanalysis based on the phase model, forming the Au/Pd(100) interface induces\nhybridization of the wave function of d-electron quantum-well states, and\nmodulates the term of the scattering phase shift as a function of the\nreciprocal lattice point. In contrast, forming the Al interface, which has only\ns-electrons at the Fermi energy, cannot modify the scattering phase shift. Our\nfinding indicates the possibility of modifying the phase shift by tailoring the\ninterface electronic states using hybridization of the wave function, and this\nefficiently changes the density of states near the Fermi energy of Pd films,\nand the switching between paramagnetism and ferromagnetism occurs based on the\ncondition for ferromagnetism (Stoner criterion)."
    },
    {
        "anchor": "Scaling Behavior of Portevin-Le Chatelier Effect: The scaling behavior of the Portevin-Le Chatelier (PLC) effect is studied by\ndeforming a substitutional alloy, Al-2.5%Mg and an interstitial alloy, low\ncarbon steel (0.15%C, 0.33%Mn, 0.04%P, 0.05%S, 0.15%Si and rest Iron) at room\ntemperature for a wide range of strain rates. To reveal the exact scaling\nnature, the time series data of true stress vs. time, obtained during the\ntensile deformation (corrected for drift due to strain hardening by polynomial\nfitting method), are analyzed by two complementary methods: the standard\ndeviation analysis and the diffusion entropy analysis. From these analyses we\ncould establish that in the entire span of strain rates, PLC effect showed Levy\nwalk type of scaling property.",
        "positive": "Intraband divergences in third order optical response of 2D systems: The existence of large nonlinear optical coefficients is one of the\npreconditions for using nonlinear optical materials in nonlinear optical\ndevices. For a crystal, such large coefficients can be achieved by matching\nphoton energies with resonant energies between different bands, and so the\ndetails of the crystal band structure play an important role. Here we\ndemonstrate that large third-order nonlinearities can also be generally\nobtained by a different strategy: As any of the incident frequencies or the sum\nof any two or three frequencies approaches zero, the doped or excited\npopulations of electronic states lead to divergent contributions in the induced\ncurrent density. We refer to these as intraband divergences, by analogy with\nthe behavior of Drude conductivity in linear response. Physically, such\nresonant processes can be associated with a combination of inraband and\ninterband optical transitions. Current-induced second order nonlinearity,\ncoherent current injection, and jerk currents are all related to such\ndivergences, and we find similar divergences in degenerate four wave mixing and\ncross-phase modulation under certain conditions. These divergences are limited\nby intraband relaxation parameters, and lead to a large optical response from a\nhigh quality sample; we find they are very robust with respect to variations in\nthe details of the band structure. To clearly track all of these effects, we\nanalyze gapped graphene, describing the electrons as massive Dirac fermions;\nunder the relaxation time approximation, we derive analytic expressions for the\nthird order conductivities, and identify the divergences that arise in\ndescribing the associated nonlinear phenomena."
    },
    {
        "anchor": "On the electric conductivity of highly ordered monolayers of\n  monodisperse metal nanoparticles: Monolayers of colloidally synthesized cobalt-platinum nanoparticles of\ndifferent diameters characterized by TEM (transmission electron microscopy)\nwere deposited on structured silicon oxide substrates and characterized by SEM\n(scanning electron microscopy), GISAXS (grazing incidence x-ray scattering),\nand electric transport measurements. The highly ordered nanoparticle films show\na thermally activated electron hopping between spatially adjacent particles at\nroom temperature and Coulomb blockade at low temperatures. We present a novel\napproach to experimentally determine the particles charging energies giving\nvalues of 6.7-25.4 meV dependent on the particles size and independent of the\ninterparticle distance. These observations are supported by FEM (finite element\nmethod) calculations showing the self-capacitance to be the determining value\nwhich only depends on the permittivity constant of the surrounding space and\nthe particles radius.",
        "positive": "Stacking polymorphism in PtSe$_2$ drastically affects its\n  electromechanical properties: PtSe$_2$ is one of the most promising materials for the next generation of\npiezoresistive sensors. However, the large-scale synthesis of homogeneous thin\nfilms with reproducible electromechanical properties is challenging due to\npolycrystallinity. We show that stacking phases other than the AA-stacking in\nthe 1T phase become thermodynamically available at elevated temperatures. We\nshow that these can make up a significant fraction in a polycrystalline thin\nfilm and discuss methods to characterize these stacking phases. Lastly, we\nestimate their gauge factors, which vary strongly and significantly impact the\nperformance of a nanoelectromechanical device."
    },
    {
        "anchor": "Lattice dynamics of KAgF3 perovskite, unique 1D antiferromagnet: Theoretical DFT calculations using GGA+U and HSE06 frameworks enabled\nvibrational mode assignment and partial (atomic) phonon DOS determination in\nKAgF3 perovskite, a low-dimensional magnetic fluoroargentate(II). Twelve bands\nin the spectra of KAgF3 were assigned to either IR active or Raman active\nmodes, reaching very good correlation with experimental values (R2>0.997).\nLow-temperature Raman measurements indicate that the intriguing\nspin-Peierls-like phase transition at 230 K is an order-disorder transition and\nit does not strongly impact the vibrational structure of the material.",
        "positive": "Graphene, a material for high temperature devices; intrinsic carrier\n  density, carrier drift velocity, and lattice energy: Heat has always been a killing matter for traditional semiconductor machines.\nThe underlining physical reason is that the intrinsic carrier density of a\ndevice made from a traditional semiconductor material increases very fast with\na rising temperature. Once reaching a temperature, the density surpasses the\nchemical doping or gating effect, any p-n junction or transistor made from the\nsemiconductor will fail to function. Here, we measure the intrinsic Fermi level\n(|E_F|=2.93k_B*T) or intrinsic carrier density (n_in=3.87*10^6 cm^-2 K^-2*T^2),\ncarrier drift velocity, and G mode phonon energy of graphene devices and their\ntemperature dependencies up to 2400 K. Our results show intrinsic carrier\ndensity of graphene is an order of magnitude less sensitive to temperature than\nthose of Si or Ge, and reveal the great potentials of graphene as a material\nfor high temperature devices. We also observe a linear decline of saturation\ndrift velocity with increasing temperature, and identify the temperature\ncoefficients of the intrinsic G mode phonon energy. Above knowledge is vital in\nunderstanding the physical phenomena of graphene under high power or high\ntemperature."
    },
    {
        "anchor": "Structure-transport correlation reveals anisotropic charge transport in\n  coupled PbS nanocrystal superlattices: Semiconductive nanocrystals (NCs) can be self-assembled into ordered\nsuperlattices (SLs) to create artificial solids with emerging collective\nproperties. Computational studies have predicted that properties such as\nelectronic coupling or charge transport are determined not only by the\nindividual NCs but also by the degree of their organization and structure.\nHowever, experimental proof for a correlation between structure and charge\ntransport in NC SLs is still pending. Here, we perform X-ray nano-diffraction\nand apply Angular X-ray Cross-Correlation Analysis (AXCCA) to characterize the\nstructures of coupled PbS NC SLs, which are directly correlated with the\nelectronic properties of the same SL microdomains. We find strong evidence for\nthe effect of SL crystallinity on charge transport and reveal anisotropic\ncharge transport in highly ordered monocrystalline hexagonal close-packed PbS\nNC SLs, caused by the dominant effect of shortest interparticle distance. This\nimplies that transport anisotropy should be a general feature of weakly coupled\nNC SLs.",
        "positive": "Stability of gold nanowires at large Au-Au separations: The unusual structural stability of gold nanowires at large separations of\ngold atoms is explained from first-principles quantum mechanical calculations.\nWe show that undetected light atoms, in particular hydrogen, stabilize the\nexperimentally observed structures, which would be unstable in pure gold wires.\nThe enhanced cohesion is due to the partial charge transfer from gold to the\nlight atoms. This finding should resolve a long-standing controversy between\ntheoretical predictions and experimental observations."
    },
    {
        "anchor": "Thermodynamic approach to liquid-to-glass transformation as an arrest\n  transition in polydisperse solution: Thermodynamic multi-component solution solidification approach to\nliquid-to-glass transition is proposed and actual mechanisms underlying\nvitrification, other than viscous slowdown, are identified. Due to polydisperse\naggregation in liquid state, glass-forming liquids, irrespective of chemical\ncomposition, appear to be mixtures of various quasi-components whose\nthermodynamic quantities shall be expressed not in terms of molar\nconcentrations of actual chemical components, but in terms of relative\nconcentrations of dominant structural units. Thermodynamically, any\nglass-former is expected to behave as multi-component solution and solidify in\ncontinuous temperature range between apparent liquidus and solidus temperatures\nthat can be identified as glass-transition range. Using extended irreversible\nthermodynamics of polydisperse solutions it is demonstrated that upon\nquenching, diffusional and Brownian mass transport in such solutions is negated\nwithin heat removal timescale, which results in dynamical arrest of nucleation\nand growth in clusters and solid-liquid phase separation. Rapid solution\nsolidification proceeds via successive cluster freezing in continuous\ntemperature range, in line with cluster size dispersity, which can be described\nin terms of percolation in static polydisperse fractal ensemble where glass\ntransition temperature naturally emerges as percolation threshold.\nMulti-component solution solidification framework is shown to be reconcilable\nqualitatively and quantitatively with the Mode Coupling - Random First Order\nTransition scenario. Finally, it is demonstrated that liquid-to-glass\ntransformation is thermodynamic liquid-to-solid phase transition, glassy state\nof matter appears to be solid supersaturated solution of defects in otherwise\nperfect matrix, and the true equilibrium structure which glass is unable access\nis a crystalline one.",
        "positive": "Tuning the gap in bilyaer graphene using chemical functionalization: DFT\n  calculations: Opening, in a controllable way, the energy gap in the electronic spectrum of\ngraphene is necessary for many potential applications, including an efficient\ncarbon-based transistor. We have shown that this can be achieved by chemical\nfunctionalization of bilayer graphene. Using various dopants, such as H, F, Cl,\nBr, OH, CN, CCH, NH2, COOH, and CH3 one can vary the gap smoothly between 0.64\nand 3 eV and the state with the energy gap is stable corresponding to the\nlowest-energy configurations. The peculiarities of the structural properties of\nbilayer graphene in comparison with bulk graphite are discussed."
    },
    {
        "anchor": "Fully analytic valence force fields for the relaxation of group-IV\n  semiconductor alloys: elastic properties of group-IV materials calculated\n  from first principles: Si$_{y}$Ge$_{1-x-y}$(C,Sn,Pb)$_{x}$ alloys have attracted significant\nattention as a route to achieve a direct-gap group-IV semiconductor. Using\ndensity functional theory (DFT) - employing local density approximation and\nhybrid Heyd-Scuzeria-Ernzerhof exchange-correlation functionals - we compute\nthe lattice parameters, relaxed and inner elastic constants, and internal\nstrain (Kleinman) parameters for elemental (diamond) group-IV materials and\nzinc blende IV-IV compounds. Our DFT calculations support a little-known\nexperimental re-evaluation of the $\\alpha$-Sn elastic constants, and contradict\na recent prediction of dynamic instability in selected IV-IV compounds.\nDFT-calculated structural and elastic properties are used in conjunction with a\nrecently derived analytical parametrisation of a harmonic valence force field\n(VFF) [Phys. Rev. B 100, 094112 (2019)] to obtain a complete set of VFF\npotentials for Si$_{y}$Ge$_{1-x-y}$(C,Sn,Pb)$_{x}$ and Si$_{x}$Ge$_{1-x}$\nalloys. The analytical parametrisation exactly reproduces the relaxed elastic\nconstants and Kleinman parameter without recourse to numerical fitting,\nallowing for accurate and computationally inexpensive lattice relaxation. The\naccuracy of the VFF potentials is demonstrated via comparison to the results of\nDFT supercell relaxation for (i) ordered Si (Ge) alloy supercells containing a\nsubstitutional C, Ge (Si), Sn or Pb impurity, where comparison is also made to\na model analytical VFF, and (ii) disordered Si$_{x}$Ge$_{1-x}$ alloy\nsupercells. The VFF potentials we present enable accurate and computationally\ninexpensive relaxation of large-scale supercells representing bulk-like\ngroup-IV alloys or group-IV heterostructures, providing input to first\nprinciples or empirical electronic structure calculations, and enabling\nstructural analysis and calculation of strain fields in heterostructures for\ndevice applications.",
        "positive": "New ultrahigh pressure phases of H2O ice predicted using an adaptive\n  genetic algorithm: We propose three new phases of H2O under ultrahigh pressure. Our structural\nsearch was performed using an adaptive genetic algorithm which allows an\nextensive exploration of crystal structure. The new sequence of\npressure-induced transitions beyond ice X at 0 K should be ice X - Pbcm - Pbca\n- Pmc21 - P21 - P21/c phases. Across the Pmc21 - P21 transition, the\ncoordination number of oxygen increases from 4 to 5 with a significant increase\nof density. All stable crystalline phases have nonmetallic band structures up\nto 7 TPa."
    },
    {
        "anchor": "Temperature dependence of relativistic valence band splitting induced by\n  an altermagnetic phase transition: Altermagnetic (AM) materials exhibit non-relativistic, momentum-dependent\nspin-split states, ushering in new opportunities for spin electronic devices.\nWhile the characteristics of spin-splitting have been documented within the\nframework of the non-relativistic spin group symmetry, there has been limited\nexploration of the inclusion of relativistic symmetry and its impact on the\nemergence of a novel spin-splitting in the band structure. This study delves\ninto the intricate relativistic electronic structure of an AM material,\nalpha-MnTe. Employing temperature-dependent angle-resolved photoelectron\nspectroscopy across the AM phase transition, we elucidate the emergence of a\nrelativistic valence band splitting concurrent with the establishment of\nmagnetic order. This discovery is validated through disordered local moment\ncalculations, modeling the influence of magnetic order on the electronic\nstructure and confirming the magnetic origin of the observed splitting. The\ntemperature-dependent splitting is ascribed to the advent of relativistic\nspin-splitting resulting from the strengthening of AM order in alpha-MnTe as\nthe temperature decreases. This sheds light on a previously unexplored facet of\nthis intriguing material.",
        "positive": "Optical Properties and Structure of Most Stable Subnanometer (ZnAs2)n\n  Clusters: ZnAs2 nanoclusters were fabricated by incorporation into pores of zeolite\nNa-X and by laser ablation. Absorption and photoluminescence spectra of ZnAs2\nnanoclusters in zeolite were measured at the temperatures of 4.2, 77 and 293 K.\nBoth absorption and PL spectra consist of two bands which demonstrate the blue\nshift from the line of free exciton in bulk crystal. We performed the\ncalculations aimed to find the most stable clusters in the size region up to\nsize of the zeolite Na-X supercage. The most stable clusters are (ZnAs2)6 and\n(ZnAs2)8 with binding energies of 7.181 eV and 8.012 eV per (ZnAs2)1 formula\nunit respectively. Therefore, we attributed two bands observed in absorption\nand PL spectra to these stable clusters. The measured Raman spectrum of ZnAs2\nclusters in zeolite was explained to be originated from (ZnAs2)6 and (ZnAs2)8\nclusters as well. The PL spectrum of ZnAs2 clusters produced by laser ablation\nconsists of a single band which has been attributed to emission of (ZnAs2)8\ncluster."
    },
    {
        "anchor": "Unraveling heat transport and dissipation in suspended MoSe$_2$ crystals\n  from bulk to monolayer: Understanding thermal transport in layered transition metal dichalcogenide\n(TMD) crystals is crucial for a myriad of applications exploiting these\nmaterials. Despite significant efforts, several basic thermal transport\nproperties of TMDs are currently not well understood. Here, we present a\ncombined experimental-theoretical study of the intrinsic lattice thermal\nconductivity of the representative TMD MoSe$_2$, focusing on the effect of\nmaterial thickness and the material's environment. We use Raman thermometry\nmeasurements on suspended crystals, where we identify and eliminate crucial\nartefacts, and perform $ab$ $initio$ simulations with phonons at finite, rather\nthan zero, temperature. We find that phonon dispersions and lifetimes change\nstrongly with thickness, yet (sub)nanometer thin TMD films exhibit a similar\nin-plane thermal conductivity ($\\sim$20~Wm$^{-1}$K$^{-1}$) as bulk crystals\n($\\sim$40~Wm$^{-1}$K$^{-1}$). This is the result of compensating phonon\ncontributions, in particular low-frequency modes with a surprisingly long mean\nfree path of several micrometers that contribute significantly to thermal\ntransport for monolayers. We furthermore demonstrate that out-of-plane heat\ndissipation to air is remarkably efficient, in particular for the thinnest\ncrystals. These results are crucial for the design of TMD-based applications in\nthermal management, thermoelectrics and (opto)electronics.",
        "positive": "Phase transition at 350 K in the Ti$_3$C$_2$T$_x$ MXene: possible\n  sliding (moir\u00e9) ferroelectricity: A phase transition is found in Ti$_3$C$_2$T$_x$ MXene at 350 K, by measuring\nthe complex Young's modulus of self-standing thick films. A step-like softening\nand increase of the mechanical losses is found below 350 K, indicative of a\nphase transition, where the square of the order parameter is coupled to strain.\nIt is argued that it should be a ferroelectric transition, most likely of the\nsliding (moir\\'e) type, due to charge transfer between facing flakes sliding\nwith respect to each other. If the transition will be confirmed to be\nferroelectric, Ti$_3$C$_2$T$_x$ will be added to the class of metallic\nferroelectrics and open new perspectives of applications, in addition to the\nnumerous already studied."
    },
    {
        "anchor": "Defects-driven appearance of half-metallic ferrimagnetism in\n  Co-Mn--based Heusler alloys: Half-metallic ferromagnetic full-Heusler alloys containing Co and Mn, having\nthe formula Co$_2$MnZ where Z a sp element, are among the most studied Heusler\nalloys due to their stable ferromagnetism and the high Curie temperatures which\nthey present. Using state-of-the-art electronic structure calculations we show\nthat when Mn atoms migrate to sites occupied in the perfect alloys by Co, these\nMn atoms have spin moments antiparallel to the other transition metal atoms.\nThe ferrimagnetic compounds, which result from this procedure, keep the\nhalf-metallic character of the parent compounds and the large\nexchange-splitting of the Mn impurities atoms only marginally affects the width\nof the gap in the minority-spin band. The case of [Co$_{1-x}$Mn$_x$]$_2$MnSi is\nof particular interest since Mn$_3$Si is known to crystallize in the Heusler\n$L2_1$ lattice structure of Co$_2$MnZ compounds. Robust half-metallic\nferrimagnets are highly desirable for realistic applications since they lead to\nsmaller energy losses due to the lower external magnetic fields created with\nrespect to their ferromagnetic counterparts.",
        "positive": "First-principles studies of Schottky barriers and tunneling properties\n  at Al(111)/Si(111) and CoSi$_2$(111)/Si(111) interfaces: We present first-principles calculations of Schottky barrier heights (SBHs)\nat interfaces relevant for silicon-based merged-element transmon qubit devices.\nFocusing on Al(111)/Si(111) and CoSi$_2$(111)/Si(111), we consider various\npossible interfacial structures, for which we study the relaxations of the\natoms near the interface, calculate the formation energies and Schottky barrier\nheights, and provide estimates of the Josephson critical currents based on the\nWKB tunneling formalism as implemented in the Simmons/Tsu-Esaki model. We find\nthat the formation energies and SBHs are very similar for all Al(111)/Si(111)\nstructures, yet vary significantly for the CoSi$_2$(111)/Si(111) structures. We\nattribute this to the more covalent character of bonding at CoSi$_2$/Si, which\nleads to configurations with distinct atomic and electronic structure. Our\nestimated Josephson critical currents, which govern the behavior of\nmerged-element transmons, provide insight into the trends as a function of\nSchottky-barrier height. We show that desirable qubit frequencies of 4-5 GHz\ncan be obtained with a Si barrier thickness of about 5-10 nm, and demonstrate\nthat the critical current density as a function of Schottky barrier height can\nbe modeled based on the tunneling probability for a rectangular barrier."
    },
    {
        "anchor": "The role of surface defects in the adsorption of methanol on Fe3O4(001): The adsorption of methanol (CH3OH) at the Fe3O4(001)-c(2x2) surface was\nstudied using X-ray photoelectron spectroscopy (XPS), scanning tunneling\nmicroscopy (STM), and temperature-programmed desorption (TPD). CH3OH adsorbs\nexclusively at surface defects sites at room temperature to form hydroxyl\ngroups and methoxy (CH3O) species. Active sites are identified as step edges,\niron adatoms, antiphase domain boundaries in the c(2x2) reconstruction, and\nabove Fe atoms incorporated in the subsurface. In TPD, recombinative desorption\nis observed around 300 K, and a disproportionation reaction to form methanol\nand formaldehyde occurs at 470 K.",
        "positive": "Thermal Conductivity of Chirality-Sorted Carbon Nanotube Networks: The thermal properties of single-walled carbon nanotubes (SWNTs) are of\nsignificant interest, yet their dependence on SWNT chirality has been, until\nnow, not explored experimentally. Here we used electrical heating and infrared\nthermal imaging to simultaneously study thermal and electrical transport in\nchirality-sorted SWNT networks. We examined solution processed 90%\nsemiconducting, 90% metallic, purified unsorted (66% semiconducting), and\nas-grown HiPco SWNT films. The thermal conductivities of these films range from\n80 to 370 W/m/K but are not controlled by chirality, instead being dependent on\nthe morphology (i.e. mass and junction density, quasi-alignment) of the\nnetworks. The upper range of the thermal conductivities measured is comparable\nto that of the best metals (Cu and Ag) but with over an order of magnitude\nlower mass density. This study reveals important factors controlling the\nthermal properties of light-weight chirality-sorted SWNT films, for potential\nthermal and thermoelectric applications."
    },
    {
        "anchor": "Hourglass Weyl loops in two dimensions: Theory and material realization\n  in monolayer GaTeI family: Nodal loops in two-dimensional (2D) systems are typically vulnerable against\nspin-orbit coupling (SOC). Here, we explore 2D systems with a type of doubly\ndegenerate nodal loops that are robust under SOC and feature an hourglass type\ndispersion. We present symmetry conditions for realizing such hourglass Weyl\nloops, which involve nonsymmorphic lattice symmetries. Depending on the\nsymmetry, the loops may exhibit different patterns in the Brillouin zone. Based\non first-principles calculations, we identify the monolayer GaTeI-family\nmaterials as a realistic material platform to realize such loops. These\nmaterials host a single hourglass Weyl loop circling around a high-symmetry\npoint. Interestingly, there is also a spin-orbit Dirac point enabled by an\nadditional screw axis. We show that the hourglass Weyl loop and the Dirac point\nare robust under a variety of applied strains. By breaking the screw axis, the\nDirac point can be transformed into a second Weyl loop. Furthermore, by\nbreaking the glide mirror, the hourglass Weyl loop and the spin-orbit Dirac\npoint can both be transformed into a pair of spin-orbit Weyl points. Our work\noffers guidance and realistic material candidates for exploring fascinating\nphysics of several novel 2D emergent fermions.",
        "positive": "Using Ripley's K-function to Characterize Clustering In 3-Dimensional\n  Point Patterns With a Case Study in Atom Probe Tomography: The size and structure of spatial molecular and atomic clustering can\nsignificantly impact material properties and is therefore important to\naccurately quantify. Ripley's K-function (K(r)), a measure of spatial\ncorrelation, can be used to perform such quantification when the material\nsystem of interest can be represented as a marked point pattern. This work\ndemonstrates how machine learning models based on K(r)-derived metrics can\naccurately estimate cluster size and intra-cluster density in simulated three\ndimensional (3D) point patterns containing spherical clusters of varying size;\nover 90% of model estimates for cluster size and intra-cluster density fall\nwithin 11% and 18% error of the true values, respectively. These K(r)-based\nsize and density estimates are then applied to an experimental APT\nreconstruction to characterize MgZn clusters in a 7000 series aluminum alloy.\nWe find that the estimates are more accurate, consistent, and robust to user\ninteraction than estimates from the popular maximum separation algorithm. Using\nK(r) and machine learning to measure clustering is an accurate and repeatable\nway to quantify this important material attribute."
    },
    {
        "anchor": "The role of magnetic anisotropy in spin filter junctions: We have fabricated oxide based spin filter junctions in which we demonstrate\nthat magnetic anisotropy can be used to tune the transport behavior of spin\nfilter junctions. Until recently, spin filters have been largely comprised of\npolycrystalline materials where the spin filter barrier layer and one of the\nelectrodes are ferromagnetic. These spin filter junctions have relied on the\nweak magnetic coupling between one ferromagnetic electrode and a barrier layer\nor the insertion of a nonmagnetic insulating layer in between the spin filter\nbarrier and electrode. We have demonstrated spin filtering behavior in\nLa0.7Sr0.3MnO3/chromite/Fe3O4 junctions without nonmagnetic spacer layers where\nthe interface anisotropy plays a significant role in determining transport\nbehavior. Detailed studies of chemical and magnetic structure at the interfaces\nindicate that abrupt changes in magnetic anisotropy across the\nnon-isostructural interface is the cause of the significant suppression of\njunction magnetoresistance in junctions with MnCr2O4 barrier layers.",
        "positive": "Stable Aqueous Dispersions of Optically and Electronically Active\n  Phosphorene: Understanding and exploiting the remarkable optical and electronic properties\nof phosphorene require mass production methods that avoid chemical degradation.\nWhile solution-based strategies have been developed for scalable exfoliation of\nblack phosphorus, these techniques have thus far employed anhydrous organic\nsolvents in an effort to minimize exposure to known oxidants, but at the cost\nof limited exfoliation yield and flake size distribution. Here, we present an\nalternative phosphorene production method based on surfactant-assisted\nexfoliation and post-processing of black phosphorus in deoxygenated water. From\ncomprehensive microscopic and spectroscopic analysis, this approach is shown to\nyield phosphorene dispersions that are stable, highly concentrated, and\ncomparable to micromechanically exfoliated phosphorene in structure and\nchemistry. Due to the high exfoliation efficiency of this process, the\nresulting phosphorene flakes are thinner than anhydrous organic solvent\ndispersions, thus allowing the observation of layer-dependent photoluminescence\ndown to the monolayer limit. Furthermore, to demonstrate preservation of\nelectronic properties following solution processing, the aqueous-exfoliated\nphosphorene flakes are employed in field-effect transistors with high drive\ncurrents and current modulation ratios. Overall, this method enables the\nisolation and mass production of few-layer phosphorene, which will accelerate\nongoing efforts to realize a diverse range of phosphorene-based applications."
    },
    {
        "anchor": "Cubic to hexagonal iron phase transition promoted by interstitial\n  hydrogen: Using ab-initio density functional theory we study the role of interstitial\nhydrogen on the energetics of the phase transformation of iron from bcc to hcp\nalong Bain's pathway. The impurity creates an internal stress field that can be\nreleased through a tetragonal distortion of the lattice, promoting the bcc\n(ferromagnetic) $\\rightarrow$ fcc (frustrated antiferromagnetic) $\\rightarrow$\nhcp (ferromagnetic) transition. The transformation between crystal systems is\naccompanied by a drastic magnetic reorganization and sudden variations of the\nunit cell volume, that can be one of the reasons for embrittlement and\nmechanical failure of iron upon hydrogen adsorption.",
        "positive": "Reversible modulation of metal-insulator transition in VO2 via\n  chemically-induced oxygen migration: Metal-insulator transitions (MIT),an intriguing correlated phenomenon induced\nby the subtle competition of the electrons' repulsive Coulomb interaction and\nkinetic energy, is of great potential use for electronic applications due to\nthe dramatic change in resistivity. Here, we demonstrate a reversible control\nof MIT in VO2 films via oxygen stoichiometry engineering. By facilely\ndepositing and dissolving a water-soluble yet oxygen-active Sr3Al2O6 capping\nlayer atop the VO2 at room temperature, oxygen ions can reversibly migrate\nbetween VO2 and Sr3Al2O6, resulting in a gradual suppression and a complete\nrecovery of MIT in VO2. The migration of the oxygen ions is evidenced in a\ncombination of transport measurement, structural characterization and\nfirst-principles calculations. This approach of chemically-induced oxygen\nmigration using a water-dissolvable adjacent layer could be useful for advanced\nelectronic and iontronic devices and studying oxygen stoichiometry effects on\nthe MIT."
    },
    {
        "anchor": "Vortices in Kekulene Molecules: Kekulene is an aromatic hydrocarbon with formula C48H24 arranged in the shape\nof a closed super-ring as shown in Fig. 2. It consists of a sublattice with 48\nC atoms with spin 5/2 and a 24 hydrogen sublattice with spin 2. In this\ncommunication, we use Monte Carlo simulations to determine the magnetic\nstructures present in Kekulene for several temperatures (T) and dipole\nanisotropies ({\\delta} = D/J). Our results show that there are two regimes at\nlow temperature separated by a crossover at 2.5 < {\\delta}cross < 3.0. For\n{\\delta} < {\\delta}cross the ground state has a unique vortex configuration. In\nthe region {\\delta} > {\\delta}cross arrangements of vortices-antivortices\n(V-AV) appears. As temperature raises the vortex structure disorders and small\noscillations take over. The importance on synthesizing this molecule grounds in\nthe possibility of building real planar structures of sizes at least 10 times\nsmaller than the earlier proposed permalloy nanodots. It is worthy to mention\nthat Kekulene is a planar structure with atomic thickness, which is a great\nadvantage compared with other nanomagnetic structures.",
        "positive": "Many-body theory of pump-probe spectra for highly excited semiconductors: We present a unified theory for pump-probe spectra in highly excited\nsemiconductors, which is applicable throughout the whole density regime\nincluding the high-density electron-hole BCS state and the low-density\nexcitonic Bose-Einstein condensate (BEC). The analysis is based on the BCS-like\npairing theory combined with the Bethe-Salpeter (BS) equation, which first\nenables us to incorporate the state-filling effect, the band-gap\nrenormalization and the strong/weak electron-hole pair correlations in a\nunified manner. We show that the electron-hole BCS state is distinctly\nstabilized by the intense pump-light, and this result strongly suggests that\nthe macroscopic quantum state can be observed under the strong photoexcitation.\nThe calculated spectra considerably deviate from results given by the BCS-like\nmean field theory and the simple BS equation without electron-hole pair\ncorrelation especially in the intermediate density states between the\nelectron-hole BCS state and the excitonic BEC state. In particular, we find the\nsharp stimulated emission and absorption lines which originate from the optical\ntransition accompanied by the collective phase fluctuation mode in the\nelectron-hole BCS state. From the pump-probe spectral viewpoint, we show that\nthis fluctuation mode changes to the exciton mode with decreasing carrier\ndensity"
    },
    {
        "anchor": "Re-entrant phase transitions and dynamics of a nanoconfined ionic liquid: Ionic liquids constrained at interfaces or restricted in subnanometric pores\nare increasingly employed in modern technologies, including energy\napplications. Understanding the details of their behavior in these conditions\nis therefore critical. By using molecular dynamics simulation, we clarify\ntheoretically and numerically the effect of confinement at the nanoscale on the\nstatic and dynamic properties of an ionic liquid. In particular, we focus on\nthe interplay among the size of the ions, the slit pore width, and the length\nscale associated to the long-range organization of polar and apolar domains\npresent in the bulk material. By modulating both the temperature and the extent\nof the confinement, we demonstrate the existence of a complex reentrant phase\nbehavior, including isotropic liquid and liquid-crystal-like phases with\ndifferent symmetries. We show how these changes impact the relative\norganization of the ions, with substantial modifications of the Coulombic\nordering, and their dynamical state. In this respect, we reveal a remarkable\ndecoupling of the dynamics of the counterions, pointing to very different roles\nplayed by these in charge transport under confinement. We finally discuss our\nfindings in connection with very recent experimental and theoretical work.",
        "positive": "Dynamics of Electrons in Gradient Nanostructures (Exactly Solvable\n  Model): A flexible multi-parameter exactly solvable model of potential profile,\ncontaining an arbitrary number of continuous smoothly shaped barriers and\nwells, both equal or unequal, characterized by finite values and continuous\nprofiles of the potential and of its gradient, is presented. We demonstrate an\ninfluence of both gradient and curvature of these potentials on the electron\ntransport and spectra of symmetric and asymmetric double-well (DW) potentials.\nThe use of this model is simplified due to one to one correspondence between\nthe algorithms of calculation of the transmittance of convex barriers and\nenergy spectra of concave wells. We have shown that the resonant contrast\nbetween maximum and minimum in over-barrier reflectivity of curvilinear barrier\nexceeds significantly the analogous effect for rectangular barrier with the\nsame height and width. Reflectionless tunneling of electrons below the bottom\nof gradient nanostructures forming concave potential barriers is considered.\nThe analogy between dynamics of electrons in gradient fields and gradient\noptics of heterogeneous photonic barriers is illustrated."
    },
    {
        "anchor": "Defeating depolarizing fields with artificial flux closure in ultrathin\n  ferroelectrics: Material surfaces encompass structural and chemical discontinuities that\noften lead to the loss of the property of interest in the so-called dead\nlayers. It is notably problematic in nanoscale oxide electronics, where the\nintegration of strongly correlated materials into devices is obstructed by the\nthickness threshold required for the emergence of their functionality. Here, we\nreport the stabilization of ultrathin out-of-plane ferroelectricity in oxide\nheterostructures through the design of an artificial flux-closure architecture.\nInserting an in-plane polarized ferroelectric epitaxial buffer provides\ncontinuity of polarization at the interface, and despite its insulating nature\nwe observe the emergence of polarization in our out-of-plane-polarized model\nferroelectric BaTiO$_{3}$ from the very first unit cell. In BiFeO$_{3}$, the\nflux-closure approach stabilizes a conceptually novel 251$^{\\circ}$ domain\nwall. Its unusual chirality is likely associated with the ferroelectric analog\nto the Dzyaloshinskii-Moriya interaction. We thus see that in an adaptively\nengineered geometry, the depolarizing-field-screening properties of an\ninsulator can even surpass those of a metal and be a source of new\nfunctionalities. This should be a useful insight on the road towards the next\ngeneration of ferroelectric-based oxide electronics.",
        "positive": "Nano Imprint Lithography on Silica Sol-gels: a simple route to\n  sequential patterning: Since the pioneering work of S.Y. Chou et al.[1] Nano Imprint Lithography\n(NIL) has emerged as a promising technique for surface patterning, opening for\nnumerous applications ranging from nanophotonics[2] to microfluidics[3]. NIL\nbasically consists in the stamping of deformable surfaces or films. Preferred\nmaterials are thermoplastics[4] and UV curable resists[5]. So far, most papers\nreport on single imprinting methods for which the same surface is imprinted\nonly once. In the present paper, we report the imprinting of square silica\nstructures from simple line gratings and demonstrate how the specific\nthermo-rheological behavior of ICSG resists can be harnessed to form complex\nstructures by sequential imprinting at low pressures."
    },
    {
        "anchor": "A finite element analysis model to predict and optimize the mechanical\n  behaviour of bioprinted scaffolds: Bioprinting is an enabling biofabrication technique to create heterogeneous\ntissue constructs according to patient-specific geometries and compositions.\nOptimization of bioinks as per requirements for specific tissue applications is\na critical exercise in ensuring clinical translation of the bioprinting\ntechnologies. Most notably, optimum hydrogel polymer concentrations are\nrequired to ensure adequate mechanical properties of bioprinted constructs\nwithout causing significant shear stresses on cells. However, experimental\niterations are often tedious for optimizing the bioink properties. In this\nwork, a finite element modelling approach has been undertaken to determine the\neffect of different bioink parameters like composition, concentration on the\nrange of stresses being experienced by the cells in a bioprinting process. The\nstress distribution of the cells at different parts of the constructs has also\nbeen modelled. It is found that both bioink chemical compositions and\nstoichiometric concentrations can substantially alter the stress effects\nexperienced by the cells. Similarly, concentrated regions of soft cells near\nthe pore regions were found to increase stress concentrations by almost three\ntimes compared to the Von-Mises stress generated around the region of cells\naway from the pores. The study outlines the importance of finite element models\nin the rapid development of bioinks.",
        "positive": "Structural Changes Related to the Magnetic Transitions in Hexagonal\n  InMnO3: Two magnetic ordering transitions are found in InMnO3, the paramagnetic to\nantiferromagnetic transition near ~118 K and a lower possible spin rotation\ntransition near ~42 K. Multiple length scale structural measurements reveal\nenhanced local distortion found to be connected with tilting of the MnO5\npolyhedra as temperature is reduced. Strong coupling is observed between the\nlattice and the spin manifested as changes in the structure near both of the\nmagnetic ordering temperatures (at ~42 K and ~ 118 K). External parameters such\nas pressure are expected to modify the coupling."
    },
    {
        "anchor": "Point Defects in Twisted Bilayer Graphene: A Density Functional Theory\n  Study: We have used ab initio density functional theory, incorporating van der Waals\ncorrections, to study twisted bilayer graphene (TBLG) where Stone-Wales defects\nor monovacancies are introduced in one of the layers. We compare these results\nto those for defects in single layer graphene or Bernal stacked graphene. The\nenergetics of defect formation is not very sensitive to the stacking of the\nlayers or the specific site at which the defect is created, suggesting a weak\ninterlayer coupling. However signatures of the interlayer coupling are\nmanifested clearly in the electronic band structure. For the \"$\\gamma\\gamma$\"\nStone Wales defect in TBLG, we observe two Dirac cones that are shifted in both\nmomentum space and energy. This up/down shift in energy results from the\ncombined effect of a charge transfer between the two graphene layers, and a\nchemical interaction between the layers, which mimics the effects of a\ntransverse electric field. Charge density plots show that states near the Dirac\npoints have significant admixture between the two layers. For Stone Wales\ndefects at other sites in TBLG, this basic structure is modified by the\ncreation of mini gaps at energy crossings. For a monovacancy, the Dirac cone of\nthe pristine layer is shifted up in energy by $\\sim0.25$ eV due to a\ncombination of the requirements of the equilibration of Fermi energy between\nthe two layers with different numbers of electrons, charge transfer, and\nchemical interactions. Both kinds of defects increase the density of states at\nthe Fermi level. The monovacancy also results in spin polarization, with\nmagnetic moments on the defect of 1.2 - 1.8 $\\mu_B$.",
        "positive": "Effective properties of periodic tubular structures: A method is described to calculate effective tensor properties of a periodic\narray of two-phase dielectric tubes embedded in a host matrix. The method uses\nWeierstrass' quasiperodic functions for representation of the potential that\nconsiderably facilitates the problem and allows us to find an exact expression\nfor the effective tensor. For weakly interacting tubes we obtain Maxwell-like\napproximation of the effective parameter which is in very good agreement with\nexperimental results in considered examples."
    },
    {
        "anchor": "Insulator-to-metal transition in sulfur-doped silicon: We observe an insulator-to-metal (I-M) transition in crystalline silicon\ndoped with sulfur to non- equilibrium concentrations using ion implantation\nfollowed by pulsed laser melting and rapid resolidification. This I-M\ntransition is due to a dopant known to produce only deep levels at equilibrium\nconcentrations. Temperature-dependent conductivity and Hall effect measurements\nfor temperatures T > 1.7 K both indicate that a transition from insulating to\nmetallic conduction occurs at a sulfur concentration between 1.8 and 4.3 x\n10^20 cm-3. Conduction in insulating samples is consistent with variable range\nhopping with a Coulomb gap. The capacity for deep states to effect metallic\nconduction by delocalization is the only known route to bulk intermediate band\nphotovoltaics in silicon.",
        "positive": "Janus $\u03b2$-PdXY (X/Y = S, Se, Te) Materials with high Anisotropic\n  Thermoelectric Performance: Two-dimensional (2D) materials have garnered considerable attention as an\nemerging thermoelectric (TE) material owing to their unique density of state\n(DOS) near the Fermi level. We investigate the TE performance of Janus\n$\\beta$-PdXY (X/Y=S, Se, Te) monolayer materials as a function of carrier\nconcentration and mid-temperature range (300 to 800 K) by combining density\nfunctional theory (DFT) and semi-classical Boltzmann transport theory. The\nphonon dispersion spectra and AIMD simulations confirm their thermal and\ndynamical stability. The transport calculation results reveal the highly\nanisotropic TE performance for both n and p-type Janus $\\beta$-PdXY monolayers.\nMeanwhile, the coexistence of low phonon group velocity and converged\nscattering rate leads to lower lattice thermal conductivity (K_l) of 0.80 W/m\nK, 0.94 W/m K, and 0.77 W/m K along y-direction for these Janus materials.\nWhile the high TE power factor is attributed to the high Seebeck coefficient\n(S) and electrical conductivity, which is due to the degenerate top valance\nbands of these Janus monolayers. The combination of lower K_l and high-power\nfactor at 300K (800 K) leads to an optimal figure of merit (ZT) as 0.68 (2.21),\n0.86 (4.09) and 0.68 (3.63) for p-type Janus PdSSe, PdSeTe and PdSTe\nmonolayers. To capture rational electron transport properties, the effects of\nacoustic phonon scattering ($\\tau$_ac), impurity scattering ($\\tau$_imp), and\npolarized phonon scattering ($\\tau$_polar) are included in the\ntemperature-dependent electron relaxation time. These findings indicated that\nthe Janus $\\beta$-PdXY monolayers are promising candidates for TE conversion\ndevices."
    },
    {
        "anchor": "Density of States Extracted from Modified Recursion Relations: We evaluate the density of states (DOS) associated with tridiagonal symmetric\nHamiltonian matrices and study the effect of perturbation on one of its\nentries. Analysis is carried out by studying the resulting three-term recursion\nrelation and the corresponding orthogonal polynomials of the first and second\nkind. We found closed form expressions for the new DOS in terms of the original\none when perturbation affects a single diagonal or off-diagonal site or a\ncombination of both. The projected DOS is also calculated numerically and its\nrelation to the average DOS is explored both analytically and numerically.",
        "positive": "Multiferroic materials for spin-based logic devices: Logical devices based on spin waves offer the potential to avoid dissipation\nmechanisms that limit devices based on either the charge or spin of mobile\nelectrons. Multiferroic magnetoelectrics, which are materials that combine\nferroelectric and magnetic order, allow direct switching of magnetic order and\nthence of spin-wave properties using an applied electric field. The intrinsic\ncoupling between polarization and magnetic moments, generated by strong\nelectronic correlations in these multiferroic materials, is argued to provide\nnew approaches to spin-wave injection and spin-wave switching using applied\nvoltages with no external magnetic field. These effects are shown to arise in a\nphenomenological Landau theory of coupled electronic and magnetic orders in\nmultiferroic BiFeO3, and found to depend subtly on differences between the\ncrystalline and film states of this material."
    },
    {
        "anchor": "Self-Sputtering of the Lennard-Jones Crystal: The self-sputtering yield of the (100) face-centered cubic (fcc) crystal\nsurface consisting of particles interacting with the Lennard-Jones (LJ)\npotential is presented as a function of the normalized incident particle\nkinetic energy for normal incidence. Because the self-sputtering yield depends\nonly on the normalized incident energy, the yield curve presented here is the\nuniversal curve, independent of the Lennard-Jones parameters, and therefore\nserves as the fundamental reference data for the LJ system. The self-sputtering\nyield data are also compared with experimentally obtained self-sputtering\nyields of some metals, which shows reasonable agreement at relatively low ion\nincident energy where mostly deposition occurs. At higher ion energy, the\nself-sputtering of such an LJ material does not represent those of real solids.\nThis is because the repulsive interactions of the LJ potential do not represent\nthose of actual atoms at short distances. The angle dependence of the\nself-sputtering yield is also presented for some selected normalized energies.",
        "positive": "Field-Temperature Evolution of Antiferromagnetic Phases in Ludvigites\n  Ni3-xMnxBO5: The conditions for the flux growth of new Mn-Ni oxyborates with the ludwigite\nstructure are reported. Magnetic measurement data for the samples with nickel\nand manganese predominance are presented. Diamagnetic anomalies of the\nantiferromagnetic phases are established and analyzed in the framework of a\nmodel comprising two antiferromagnetically interacting subsystems, each being\nantiferromagnetically ordered."
    },
    {
        "anchor": "Magnetization and magnon excitation energies of the magnetic\n  semiconductors EuTe and EuO on the basis of the renormalized spin wave theory: We present analytic expressions for the temperature dependent magnetization\nand magnon dispersion relation of the antiferromagnetic (AFM) EuTe and the\nferromagnetic (FM) EuO. These bulk semiconductors represent concentrated spin\nsystems for which the interaction between magnons has to be taken into account.\nWe do this using the renormalized spin wave theory. A higher order Green's\nfunction according to Tjablikov is used for their description. As a result, we\nobtain a modified Bloch- T3/2 law, for low temperatures and high magnetic\nfields. A full analytic expression is given for the sublattice magnetization of\nthe AFM EuTe (B0=0), with a N\\'eel temperature of TN = 9.81 K. The\nmagnetization curves {\\sigma}N(T) of EuO (for 0 \\leq T \\leq 0.68TC) and\n{\\sigma}R(T) (for 0.82TC < T < TC) agree well with experiment. The spin wave\nexcitation energy perfectly matches experimental data from inelastic neutron\nscattering. In the case of EuTe the magnon excitation energies exhibit a\ncharacteristic maximum. For q = 0, an energy gap Eg occurs in the spin wave\nspectrum, a consequence of the AFM exchange interaction J2(T). Such energy gaps\nexist in the spectrum of magnon excitation energies only in systems with AFM\ninteractions.",
        "positive": "Prediction of a new efficient permanent magnet SmCoNiFe3: We propose a new efficient permanent magnet, SmCoNiFe3, that is a\nbreakthrough development of the well-known SmCo5 prototype. More modern\nneodymium magnets of the Nd-Fe-B type have an advantage over SmCo5 because of\ntheir greater maximum energy products due to their iron-rich stoichiometry. Our\nnew magnet, however, removes most of this disadvantage of SmCo5 while\npreserving its superior high-temperature efficiency over the neodymium magnets."
    },
    {
        "anchor": "Incipient ferroelectricity in 2.3% tensile-strained CaMnO3 films: Epitaxial CaMnO3 films grown with 2.3% tensile strain on (001)-oriented\nLaAlO3 substrates are found to be incipiently ferroelectric below 25 K. Optical\nsecond harmonic generation (SHG) was used for the detection of the incipient\npolarization. The SHG analysis reveals that CaMnO3 crystallites with in-plane\norientation of the orthorhombic b axis contribute to an electric polarization\noriented along the orthorhombic a (resp.\\ c) axis in agreement with the\npredictions from density functional calculations.",
        "positive": "Stability and Migration of Small Copper Clusters in Amorphous\n  Dielectrics: We use density functional theory (DFT) to study the thermodynamic stability\nand migration of copper ions and small clusters embedded in amorphous silicon\ndioxide. We perform the calculations over an ensemble of statistically\nindependent structures to quantify the role of the intrinsic atomic-level\nvariability in the amorphous matrix affect the properties. The predicted\nformation energy of a Cu ion in the silica matrix is 2.7+/-2.4 eV,\nsignificantly lower the value for crystalline SiO2. Interestingly, we find that\nCu clusters of any size are energetically favorable as compared to isolated\nions; showing that the formation of metallic clusters does not require\novercoming a nucleation barrier as is often assumed. We also find a broad\ndistribution of activation energies for Cu migration, from 0.4 to 1.1 eV. This\nstudy provides insights into the stability of nanoscale metallic clusters in\nsilica of interest in electrochemical metallization cell memories and\noptoelectronics."
    },
    {
        "anchor": "Revealing excess protons in the infrared spectrum of liquid water: The most common species in liquid water, next to neutral H$_2$O molecules,\nare the H$_3$O$^+$ and OH$^-$ ions. In a dynamic picture, their exact\nconcentrations depend on the time scale at which these are probed. Here, using\na spectral-weight analysis, we experimentally resolve the fingerprints of the\nelusive fluctuations-born short-living H$_3$O$^+$, DH$_2$O$^+$, HD$_2$O$^+$,\nand D$_3$O$^+$ ions in the IR spectra of light (H$_2$O), heavy (D$_2$O), and\nsemi-heavy (HDO) water. We find that short-living ions, with concentrations\nreaching $\\sim 2\\%$ of the content of water molecules, coexist with long-living\npH-active ions on the picosecond timescale, thus making liquid water an\neffective ionic liquid in femtochemistry.",
        "positive": "Role of electron and hole centers in energy transfer in BaBrI crystals: In this paper we study a role of F-centers, hole centers and excitons in\nenergy transfer in Eu-doped BaBrI crystals. Optical absorption spectra,\nthermally stimulated (TSL) and photostimulated (PSL) luminescence in wide\ntemperature range 7-300 K are studied in undoped and doped with different\nconcentrations of Eu ions BaBrI crystals. Based on experimental and calculated\nresults two possible energy transfer processes from host to Eu$^{2+}$ ions are\nestablished."
    },
    {
        "anchor": "Modelling surface restructuring by slow highly charged ions: We theoretically investigate surface modifications on alkaline earth halides\ndue to highly charged ion impact, focusing on recent experimental evidence for\nboth etch pit and nano-hillock formation on CaF2 [A. El-Said et al, PRL 109,\n117602 (2012)]. We discuss mechanisms for converting the projectile potential\nand kinetic energies into thermal energy capable of changing the surface\nstructure. A proof-of-principle classical molecular dynamics simulation\nsuggests the existence of two thresholds which we associate with etch pit and\nnano-hillock formation in qualitative agreement with experiment.",
        "positive": "Epitaxial growth and characterization of (001) [NiFe/M]$_{20}$ (M = Cu,\n  CuPt and Pt) superlattices: We present optimization of [(15 $\\unicode{x212B}$) Ni$_{80}$Fe$_{20}$/(5\n$\\unicode{xC5}$) M]$_{20}$ single crystal multilayers on (001) MgO, with M\nbeing Cu, Cu$_{50}$Pt$_{50}$ and Pt. These superlattices were characterized by\nhigh-resolution X-ray reflectivity (XRR) and diffraction (XRD) as well as polar\nmapping of important crystal planes. It is shown that cube on cube epitaxial\nrelationship can be obtained when depositing at the substrate temperature of\n100 $^\\circ$C regardless of the lattice mismatch (5% and 14% for Cu and Pt,\nrespectively). At lower substrate temperatures poly-crystalline multilayers\nwere obtained while at higher substrate temperatures {111} planes appear at\n$\\sim$10$^\\circ$ off normal to the film plane. It is also shown that as the\nepitaxial strain increases, the easy magnetization axis rotates towards the\ndirection that previously was assumed to be harder, i.e. from [110] to [100],\nand eventually further increase in the strain makes the magnetic hysteresis\nloops isotropic in the film plane. Higher epitaxial strain is also accompanied\nwith increased coercivity values. Thus, the effect of epitaxial strain on the\nmagnetocrystalline anisotropy is much larger than what was observed previously\nin similar, but polycrystalline samples with uniaxial anisotropy (Kateb et al.\n2021)."
    },
    {
        "anchor": "Electronic topological transition in LaSn$_3$ under pressure: The electronic structure, Fermi surface and elastic properties of the\niso-structural and iso-electronic LaSn$_3$ and YSn$_3$ intermetallic compounds\nare studied under pressure within the framework of density functional theory\nincluding spin-orbit coupling. The LaSn$_3$ Fermi surface consists of two\nsheets, of which the second is very complex. Under pressure a third sheet\nappears around compression $V/V_0=0.94$, while a small topology change in the\nsecond sheet is seen at compression $V/V_0=0.90$. This may be in accordance\nwith the anomalous behaviour in the superconducting transition temperature\nobserved in LaSn$_3$, which has been suggested to reflect a Fermi surface\ntopological transition, along with a non-monotonic pressure dependence of the\ndensity of states at the Fermi level. The same behavior is not observed in\nYSn$_3$, the Fermi surface of which already includes three sheets at ambient\nconditions, and the topology remains unchanged under pressure. The reason for\nthe difference in behaviour between LaSn$_3$ and YSn$_3$ is the role of\nspin-orbit coupling and the hybridization of La - $4f$ states with the Sn - $p$\nstates in the vicinity of the Fermi level, which is well explained using the\nband structure calculation. The elastic constants and related mechanical\nproperties are calculated at ambient as well as at elevated pressures. The\nelastic constants increase with pressure for both compounds and satisfy the\nconditions for mechanical stability under pressure.",
        "positive": "Quantum spin state transitions in spin-1 equilateral triangular lattice\n  antiferromagnet Na$_2$BaNi(PO$_4$)$_2$: We have grown single crystals of Na$_2$BaNi(PO$_4$)$_2$, a new spin-1\nequilateral triangular lattice antiferromagnet (ETLAF), and performed magnetic\nsusceptibility, specific heat and thermal conductivity measurements at ultralow\ntemperatures. The main results are (i) at zero magnetic field,\nNa$_2$BaNi(PO$_4$)$_2$ exhibits a magnetic ordering at 430 mK with a weak\nferromagnetic moment along the $c$ axis. This suggests a canted 120$^\\circ$\nspin structure, which is in a plane including the crystallographic $c$ axis due\nto the existence of an easy-axis anisotropy and ferromagnetically stacked along\nthe $c$ axis; (ii) with increasing field along the $c$ axis, a 1/3\nmagnetization plateau is observed which means the canted 120$^\\circ$ spin\nstructure is transformed to a up up down (UUD) spin structure. With even higher\nfields, the UUD phase further evolves to possible V and V' phases; (iii) with\nincreasing field along the $a$ axis, the canted 120$^\\circ$ spin structure is\npossibly transformed to a umbrella phase and a V phase. Therefore,\nNa$_2$BaNi(PO$_4$)$_2$ is a rare example of spin-1 ETLAF with single\ncrystalline form to exhibit easy-axis spin anisotropy and series of quantum\nspin state transitions."
    },
    {
        "anchor": "High-Throughput Density Functional Theory Screening of Double Transition\n  Metal MXene Precursors: MXenes are an emerging class of 2D materials of interest in applications\nranging from energy storage to electromagnetic shielding. MXenes are\nsynthesized by selective etching of layered bulk MAX phases into sheets of 2D\nMXenes. Their chemical tunability has been significantly expanded with the\nsuccessful synthesis of double transition metal MXenes. While knowledge of the\nstructure and energetics of double transition metal MAX phases is critical to\ndesigning and optimizing new MXenes, only a small subset of these materials\nbeen explored. We present a comprehensive dataset of key properties of MAX\nphases obtained using density functional theory within the generalized gradient\napproximation exchange-correlation functionals. Energetics and structure of\n8,712 MAX phases have been calculated and stored in a queryable, open database\nhosted at nanoHUB.",
        "positive": "Chromium hardening and Peierls mechanism for basal slip in sapphire at\n  temperatures between 900 and 1500 $^\\circ$C: The plastic deformation of Cr3+ -doped a-Al2 O3 (ruby) with four distinct Cr\nconcentrations has been studied at temperatures between 900 and 1500 $^\\circ$C.\nThe mechanical tests indicate that the processes of dislocation multiplication\nand the adjustments of the slip velocity of these dislocations to the imposed\nstrain rate in undoped a-Al2 O3 are not significantly affected by the Cr\nconcentra%on. The yield stress increment is approximately constant with\ntemperature and the hardening increases with the Cr concentration. The critical\nresolved shear stress (CRSS) is fixed to a model based on dislocation glide\ncontrolled by the nucleation and propagation of kink pairs, modified to include\nthe hardening due to Cr. Satisfactory fits are achieved with adjustable\nparameters close to those employed for undoped a-Al2 O3 ."
    },
    {
        "anchor": "Double-resonant LA phonon scattering in defective graphene and carbon\n  nanotubes: We present measurements of the $D''$ Raman mode in graphene and carbon\nnanotubes at different laser excitation energies. The Raman mode around 1050 -\n1150\\,cm$^{-1}$ originates from a double-resonant scattering process of\nlongitudinal acoustic (LA) phonons with defects. We investigate its dependence\non laser excitation energy, on the number of graphene layers and on the carbon\nnanotube diameter. We assign this Raman mode to so-called 'inner' processes\nwith resonant phonons mainly from the $\\Gamma-K$ high-symmetry direction. The\nasymmetry of the $D''$ mode is explained by additional contributions from\nphonons next to the $\\Gamma-K$ line. Our results demonstrate the importance of\ninner contributions in the double-resonance scattering process and add a fast\nmethod to investigate acoustic phonons in graphene and carbon nanotubes by\noptical spectroscopy.",
        "positive": "Optical read-out of the N\u00e9el vector in metallic antiferromagnet\n  Mn$_{2}$Au: Metallic antiferromagnets with broken inversion symmetry on the two\nsublattices, strong spin-orbit coupling and high N\\'{e}el temperatures offer\nnew opportunities for applications in spintronics. Especially Mn$_{2}$Au, with\nhigh N\\'{e}el temperature and conductivity, is particularly interesting for\nreal-world applications. Here, manipulation of the orientation of the staggered\nmagnetization,\\textit{\\ i.e.} the N\\'{e}el vector, by current pulses has been\nrecently demonstrated, with the read-out limited to studies of anisotropic\nmagnetoresistance or X-ray magnetic linear dichroism. Here, we report on the\nin-plane reflectivity anisotropy of Mn$_{2}$Au (001) films, which were N\\'{e}el\nvector aligned in pulsed magnetic fields. In the near-infrared, the anisotropy\nis $\\approx$ 0.6\\%, with higher reflectivity for the light polarized along the\nN\\'{e}el vector. The observed magnetic linear dichroism is about four times\nlarger than the anisotropic magnetoresistance. This suggests the dichroism in\nMn$_{2}$Au is a result of the strong spin-orbit interactions giving rise to\nanisotropy of interband optical transitions, in-line with recent studies of\nelectronic band-structure. The considerable magnetic linear dichroism in the\nnear-infrared could be used for ultrafast optical read-out of the N\\'{e}el\nvector in Mn$_{2}$Au."
    },
    {
        "anchor": "Atomistic hartree theory and crystal field of twisted double bilayer\n  graphene near the magic angle: Twisted double bilayer graphene (tDBLG) is a moir\\'e material that has\nrecently generated significant interest because of the observation of\ncorrelated phases near the magic angle. We carry out atomistic Hartree theory\ncalculations to study the role of electron-electron interactions in the normal\nstate. In contrast to twisted bilayer graphene (tBLG), we find that such\ninteractions do not result in significant doping-dependent deformations of the\nelectronic band structure. However, interactions play an important role for the\nelectronic structure in the presence of a perpendicular electric field as they\nscreen the external field. Finally, we analyze the contribution of the Hartree\npotential to the crystal field, i.e. the on-site energy difference between the\ninner and outer layers. We find that the on-site energy obtained from Hartree\ntheory has the same sign, but a smaller magnitude compared to previous studies\nin which the on-site energy was determined by fitting tight-binding results to\nab initio density-functional theory (DFT) band structures. To understand this\nquantitative difference, we analyze the ab initio Kohn-Sham potential obtained\nfrom DFT and find that a subtle interplay of electron-electron and electron-ion\ninteractions determines the magnitude of the on-site potential.",
        "positive": "Automated Segmentation of Large Image Datasets using Artificial\n  Intelligence for Microstructure Characterisation, Damage Analysis and\n  High-Throughput Modelling Input: Many properties of commonly used materials are driven by their\nmicrostructure, which can be influenced by the composition and manufacturing\nprocesses. To optimise future materials, understanding the microstructure is\ncritically important. Here, we present two novel approaches based on artificial\nintelligence that allow the segmentation of the phases of a microstructure for\nwhich simple numerical approaches, such as thresholding, are not applicable:\nOne is based on the nnU-Net neural network, and the other on generative\nadversarial networks (GAN). Using large panoramic scanning electron microscopy\nimages of dual-phase steels as a case study, we demonstrate how both methods\neffectively segment intricate microstructural details, including martensite,\nferrite, and damage sites, for subsequent analysis. Either method shows\nsubstantial generalizability across a range of image sizes and conditions,\nincluding heat-treated microstructures with different phase configurations. The\nnnU-Net excels in mapping large image areas. Conversely, the GAN-based method\nperforms reliably on smaller images, providing greater step-by-step control and\nflexibility over the segmentation process. This study highlights the benefits\nof segmented microstructural data for various purposes, such as calculating\nphase fractions, modelling material behaviour through finite element\nsimulation, and conducting geometrical analyses of damage sites and the local\nproperties of their surrounding microstructure."
    },
    {
        "anchor": "Pressure induced quenching of planar rattling in\n  Cu$_{10}$Zn$_{2}$Sb$_{4}$S$_{13}$ studied by specific-heat and x-ray\n  diffraction measurements: We have studied the pressure effect on the rattling of tetrahedrite\nCu$_{10}$Zn$_{2}$Sb$_{4}$S$_{13\\,}$(CZSS) and type-I clathrate\nBa$_{8}$Ga$_{16}$Sn$_{30\\,}$(BGS) by specific heat and x-ray diffraction\nmeasurements. By applying pressure $P$, the rattling energy for CZSS initially\ndecreases and steeply increases for $P$ $\\textgreater$ $1$ GPa. By contrast,\nthe energy for BGS increases monotonically with $P$ up to 6.5 GPa. An analysis\nof the pressure dependent specific heat and x-ray diffraction indicates that\nthe out-of-plane rattling of the Cu atoms in the S$_{3}$ triangle of CZSS\noriginates from the chemical pressure, unlike the rattling of the Ba ions among\noff-center sites in an oversized cage of BGS. The rattling in CZSS ceases upon\nfurther increasing $P$ above 2 GPa, suggesting that Cu atoms escape away from\nthe S$_{3}$ triangle plane.",
        "positive": "Origin of ferroelectricity in high $T_c$ magnetic ferroelectric CuO: \"Magnetic ferroelectric\" has been found in a wide range of spiral magnets.\nHowever, these materials all suffer from low critical temperatures, which are\nusually below 40 K, due to strong spin frustration. Recently, CuO has been\nfound to be multiferroic at much higher ordering temperature ($\\sim$ 230K). To\nclarify the origin of the high ordering temperature in CuO, we investigate the\nstructural, electronic and magnetic properties of CuO via first-principles\nmethods. We find that CuO has very special nearly commensurate spiral magnetic\nstructure, which is stabilized via the Dzyaloshinskii-Moriya interaction. The\nspin frustration in CuO is relatively weak, which is one of the main reasons\nthat the compound have high ordering temperature. We propose that high $T_c$\nmagnetic ferroelectric materials can be found in double sublattices of magnetic\nstructures similar to that of CuO."
    },
    {
        "anchor": "Effects of elastic heterogeneity and anisotropy on the morphology of\n  self-assembled epitaxial quantum dots: Epitaxial self-assembled quantum dots (SAQDs) are of both technological and\nfundamental interest, but their reliable manufacture still presents a technical\nchallenge. To better understand the formation, morphology and ordering of\nepitaxial self-assembled quantum dots (SAQDs), it is essential to have an\naccurate model that can aid further experiments and predict the trends in SAQD\nformation. SAQDs form because of the destabilizing effect of elastic mismatch\nstrain, but most analytic models and some numerical models of SAQD formation\neither assume an elastically homogeneous anisotropic film-substrate system or\nassume an elastically heterogeneous isotropic system. In this work, we perform\nthe full film-substrate elastic calculation. Then we incorporate the elasticity\ncalculation into a stochastic linear growth model. We find that using\nhomogeneous elasticity can cause errors in the elastic energy density as large\nas 26%, and for typical modeling parameters lead to errors of about 11% in the\nestimated value of average dot spacing. We also quantify the effect of elastic\nheterogeneity on the order estimates of SAQDs and confirm previous finding on\nthe possibility of order enhancement by growing a film near the critical film\nheight.",
        "positive": "Electrical transport in C-doped GaAs nanowires: surface effects: The resistivity and the mobility of Carbon doped GaAs nanowires have been\nstudied for different doping concentrations. Surface effects have been\nevaluated by comparing upassivated with passivated nanowires. We directly see\nthe influence of the surface: the pinning of the Fermi level and the consequent\nexistence of a depletion region lead to an increase of the mobility up to 30\ncm^2/(V*s) for doping concentrations lower than 3*10^18 cm^-3. Electron beam\ninduced current measurements show that the minority carrier diffusion path can\nbe as high as 190 nm for passivated nanowires."
    },
    {
        "anchor": "The pyrochlore Ho2Ti2O7: Synthesis, crystal growth and stoichiometry: We have investigated the effect of synthesis and growth conditions on the\nmagnetic, structural, and compositional properties of pyrochlore oxide holmium\ntitanate and demonstrate a method for growing high quality stoichiometric\nsingle crystals. A series of polycrystalline samples with various contents of\nTi (-0.08 \\leqslant x \\leqslant 0.08, and nominal compositions of Ho2Ti2+xO7)\nwere synthesized at different temperatures, and characterized using powder\nX-ray diffraction. The results show that synthesizing powders at a higher\ntemperature of 1500 {\\deg}C yield single phase compounds. Ti deficient powders\nshowed an increase of lattice constant due to stuffing (Ho into Ti positions),\nwhile Ti rich powders showed a decrease in lattice constant due to\nanti-stuffing (Ti into Ho positions). A post annealing in O2 was found to be\nnecessary to accomplish the anti-stuffing process. Use of the conventional\nfloating zone (FZ) technique introduced Ti deficiency, stuffing, and oxygen\nvacancies in the grown crystal. Growth of high structural quality and\nstoichiometric single crystals of Ho2Ti2O7 by the traveling solvent floating\nzone (TSFZ) is reported. AC susceptibility measurements revealed that the\nstoichiometric crystal shows a higher ice freezing temperature, indicating that\ncrystal quality and stoichiometry play a key role on low temperature spin ice\nproperties of this compound.",
        "positive": "Non-Relativistic Electron Transport in Metals: A Monte Carlo Approach: A simple Monte Carlo procedure is described for simulating the multiple\nscattering and absorption of electrons with the incident energy in the range\n1-50 keV moving through a slab of uniformly distributed material of given\natomic number, density and thickness. The simulation is based on a screened\nRutherford cross-section and Bethe continuous energy-loss equation. A FORTRAN\nprogram is written to determine backscattering, transmission and absorption\ncoefficients, providing the user with a graphical output of the electron\ntrajectories. The results of several simulations are presented by using various\nnumbers of electrons, showing a good agreement with the experiment. The program\nis used to analyze the relation between the energy and the range of electron in\nthe slab, the backscattering, absorption, transmission coefficients and the\nangular distribution."
    },
    {
        "anchor": "Anomalous compressibility of ferropericlase throughout the iron spin\n  crossover: The thermoelastic properties of ferropericlase Mg1-xFexO (x = 0.1875)\nthroughout the iron high-to-low spin crossover have been investigated by first\nprinciples at Earth's lower mantle conditions. This crossover has important\nconsequences for elasticity such as an anomalous bulk modulus (KS) reduction.\nAt room temperature the anomaly is somewhat sharp in pressure but broadens with\nincreasing temperature. Along a typical geotherm it occurs across most of the\nlower mantle with a more significant KS reduction around 1400-1600 km depth.\nThis anomaly might also cause a reduction in the effective activation energy\nfor viscous creep and lead to a viscosity minimum in the mid-lower mantle, in\napparent agreement with results from inversion of data related with mantle\nconvection and postglacial rebound.",
        "positive": "AFM and Raman studies of topological insulator materials subject to\n  argon plasma etching: Plasma etching is an important tool in nano-device fabrication. We report a\nstudy on argon plasma etching of topological insulator materials Bi2Se3,\nBi2Te3, Sb2Te3 and Bi2Te2Se using exfoliated flakes (with starting thicknesses\nof ~100 nm) derived from bulk crystals. We present data mainly from atomic\nforce microscopy (AFM) and Raman spectroscopy. Through AFM measurements, plasma\nexposure is observed to decrease the thickness of our samples and increase\nsurface roughness (with height fluctuations reaching as large as ~20 nm). We\nextract an etching rate for each type of material. Plasma exposure also causes\na widening (especially Eg2) of the characteristic Raman peaks, with no\nsignificant change in peak position. The overall Raman intensity is observed to\ninitially increase, then decrease sharply after the samples are etched below\n~20 nm in thickness. Our findings are valuable for understanding the effects of\nargon plasma etching on topological insulator materials."
    },
    {
        "anchor": "High-throughput screening of heterogeneous transition metal dual-atom\n  catalysts by synergistic effect for nitrate reduction to ammonia: Nitrate reduction to ammonia has attracted much attention for nitrate (NO3-)\nremoval and ammonia (NH3) production. Identifying promising catalyst for active\nnitrate electroreduction reaction (NO3RR) is critical to realize efficient\nupscaling synthesis of NH3 under low-temperature condition. For this purpose,\nby means of spin-polarized first-principles calculations, the NO3RR performance\non a series of graphitic carbon nitride (g-CN) supported double-atom catalysts\n(denoted as M1M2@g-CN) are systematically investigated. The synergistic effect\nof heterogeneous dual-metal sites can bring out tunable activity and\nselectivity for NO3RR. Amongst 21 candidates examined, FeMo@g-CN and CrMo@g-CN\npossess a high performance with low limiting potentials of -0.34 and -0.39 V,\nrespectively. The activities can be attributed to a synergistic effect of the\nM1M2 dimer d orbitals coupling with the anti-bonding orbital of NO3-. The\ndissociation of deposited FeMo and CrMo dimers into two separated monomers is\nproved to be difficult, ensuring the kinetic stability of M1M2@g-CN.\nFurthermore, the dual-metal decorated on g-CN significantly reduces the bandgap\nof g-CN and broadens the adsorption window of visible light, implying its great\npromise for photocatalysis. This work opens a new avenue for future theoretical\nand experimental design related to NO3RR photo-/electrocatalysts.",
        "positive": "In situ micropillar compression of an anisotropic metal-organic\n  framework single crystal: Understanding of the complex mechanical behavior of metal-organic frameworks\n(MOF) beyond their elastic limit will allow the design of real-world\napplications in chemical engineering, optoelectronics, energy conversion\napparatus, and sensing devices. Through in situ compression of micropillars,\nthe uniaxial stress-strain curves of a copper paddlewheel MOF (HKUST-1) were\ndetermined along two unique crystallographic directions, namely the (100) and\n(111) facets. We show strongly anisotropic elastic response where the ratio of\nthe Young's moduli are E(111) ~ 3.6 x E(100), followed by extensive plastic\nflows. Likewise, the yield strengths are considerably different, in which\nY(111) ~ 2 x Y(100) because of the underlying framework anisotropy. We measure\nthe fracture toughness using micropillar splitting. While in situ tests\nrevealed differential cracking behavior, the resultant toughness values of the\ntwo facets are comparable, yielding Kc ~ 0.5 MPa m^1/2. This work provides new\ninsights of porous framework ductility at the micron scale and failure by bonds\nbreakage."
    },
    {
        "anchor": "Role of chalcogen vacancies and hydrogen in the optical and electrical\n  properties of bulk transition-metal dichalcogenides: Like in any other semiconductor, point defects in transition-metal\ndichalcogenides (TMDs) are expected to strongly impact their electronic and\noptical properties. However, identifying defects in these layered\ntwo-dimensional materials has been quite challenging with controversial\nconclusions despite the extensive literature in the past decade. Using\nfirst-principles calculations, we revisit the role of chalcogen vacancies and\nhydrogen impurity in bulk TMDs, reporting formation energies and thermodynamic\nand optical transition levels. We show that the S vacancy can explain recently\nobserved cathodoluminescence spectra of MoS$_2$ flakes and predict similar\noptical levels in the other TMDs. In the case of the H impurity, we find it\nmore stable sitting on an interstitial site in the Mo plane, acting as a\nshallow donor, and possibly explaining the often observed n-type conductivity\nin some TMDs. We also predict the frequencies of the local vibration modes for\nthe H impurity, aiding its identification through Raman or infrared\nspectroscopy.",
        "positive": "Antiferromagnetism in NiO Observed by Transmission Electron Diffraction: Neutron diffraction has been used to investigate antiferromagnetism since\n1949. Here we show that antiferromagnetic reflections can also be seen in\ntransmission electron diffraction patterns from NiO. The diffraction patterns\ntaken here came from regions as small as 10.5 nm and such patterns could be\nused to form an image of the antiferromagnetic structure with a nanometre\nresolution."
    },
    {
        "anchor": "Sintering of Alumina Nanoparticles: Comparison of Interatomic\n  Potentials, Molecular Dynamics Simulations, and Data Analysis: Sintering of alumina nanoparticles is of interest both from the view of\nfundamental research as well as for industrial applications. Atomistic\nsimulations are tailor-made for understanding and predicting the time- and\ntemperature-dependent sintering behaviour. However, the quality and\npredictability of such analysis is strongly dependent on the performance of the\nunderlying interatomic potentials. In this work, we investigate and benchmark\nfour empirical interatomic potentials and discuss the resulting properties and\ndrawbacks based on experimental and density functional theory data from the\nliterature. The potentials, which have different origins and formulations, are\nthen used in molecular dynamics simulations to perform a systematic study of\nthe sintering process. To analyse the results, we develop a number of tailored\ndata analysis approaches that are able to characterise and quantify the\nsintering process. Subsequently, the disparities in the sintering behaviour\npredicted by the potentials are critically discussed. Finally, we conclude by\nproviding explanations for the differences in performance of the potentials,\ntogether with recommendations for molecular dynamics sintering simulations of\nalumina.",
        "positive": "Half-Metallic Silicene and Germanene Nanoribbons: towards\n  High-Performance Spintronics Device: By using first-principles calculations, we predict that an in-plane\nhomogenous electrical field can induce half-metallicity in hydrogen-terminated\nzigzag silicene and germanene nanoribbons (ZSiNRs and ZGeNRs). A dual-gated\nfinite ZSiNR device reveals a nearly perfect spin-filter efficiency of up to\n99% while a quadruple-gated finite ZSiNR device serves as an effective spin\nfield effect transistor (FET) with an on/off current ratio of over 100 from ab\ninitio quantum transport simulation. This discovery opens up novel prospect of\nsilicene and germanene in spintronics."
    },
    {
        "anchor": "Magnetic microscopy of topologically protected homochiral domain walls\n  in an ultrathin perpendicularly magnetized Co film: Next-generation concepts for solid-state memory devices are based on\ncurrent-driven domain wall propagation, where the wall velocity governs the\ndevice performance. It has been shown that the domain wall velocity and the\ndirection of travel is controlled by the nature of the wall and its chirality.\nThis chirality is attributed to effects emerging from the lack of inversion\nsymmetry at the interface between a ferromagnet and a heavy metal, leading to\nan interfacial Dzyaloshinskii-Moriya interaction that can control the shape and\nchirality of the magnetic domain wall. Here we present direct imaging of domain\nwalls in Pt/Co/AlO$_x$ films using Lorentz transmission electron microscopy,\ndemonstrating the presence of homochiral, and thus topologically protected,\nN\\'{e}el walls. Such domain walls are good candidates for dense data storage,\nbringing the bit size down close to the limit of the domain wall width.",
        "positive": "Towards a better understanding of the structure of diamano\u00efds and\n  diamano\u00efd/graphene hybrids: Hot-filament process was recently employed to convert, totally or partially,\nfew-layer graphene (FLG) with Bernal stacking into crystalline sp$^3$-C sheets\nat low pressure. Those materials constitute new synthetic carbon nanoforms. The\nresult reported earlier relies on Raman spectroscopy and Fourier transform\ninfrared microscopy. As soon as the number of graphene layers in the starting\nFLG is higher than 2-3, the sp$^2$-C to sp$^3$-C conversion tends to be partial\nonly. We hereby report new evidences confirming the sp$^2$-C to sp$^3$-C\nconversion from electron diffraction at low energy,Raman spectroscopy and\nDensity Functional Theory (DFT) calculations. Partial sp$^2$-C to sp$^3$-C\nconversion generates couples of twisted, superimposed coherent domains (TCD),\nsupposedly because of stress relaxation, which are evidenced by electron\ndiffraction and Raman spectroscopy. TCDs come with the occurrence of a twisted\nbilayer graphene feature located at the interface between the upper diamano\\\"id\ndomain and the non-converted graphenic domain underneath, as evidenced by a\nspecific Raman signature consistent with the literature. DFT calculations show\nthat the up-to-now poorly understood Raman T peak originates from a\nsp$^2$-C-sp$^3$-C mixt layer located between a highly hydrogenated sp$^3$-C\nsurface layer and an underneath graphene layer."
    },
    {
        "anchor": "Interplay of plasma-induced and fast thermal nonlinearities in a\n  GaAs-based photonic crystal nanocavity: We investigate the nonlinear response of GaAs-based photonic crystal cavities\nat time scales which are much faster than the typical thermal relaxation rate\nin photonic devices. We demonstrate a strong interplay between thermal and\ncarrier induced nonlinear effects. We have introduced a dynamical model\nentailing two thermal relaxation constants which is in very good agreement with\nexperiments. These results will be very important for Photonic Crystal-based\nnonlinear devices intended to deal with practical high repetition rate optical\nsignals.",
        "positive": "The stability of a crystal with diamond structure for patchy particles\n  with tetrahedral symmetry: The phase diagram of model anisotropic particles with four attractive patches\nin a tetrahedral arrangement has been computed at two different values for the\nrange of the potential, with the aim of investigating the conditions under\nwhich a diamond crystal can be formed. We find that the diamond phase is never\nstable for our longer-ranged potential. At low temperatures and pressures, the\nfluid freezes into a body-centred-cubic solid that can be viewed as two\ninterpenetrating diamond lattices with a weak interaction between the two\nsublattices. Upon compression, an orientationally ordered face-centred-cubic\ncrystal becomes more stable than the body-centred-cubic crystal, and at higher\ntemperatures a plastic face-centered-cubic phase is stabilized by the increased\nentropy due to orientational disorder. A similar phase diagram is found for the\nshorter-ranged potential, but at low temperatures and pressures, we also find a\nregion over which the diamond phase is thermodynamically favored over the\nbody-centred-cubic phase. The higher vibrational entropy of the diamond\nstructure with respect to the body-centred-cubic solid explains why it is\nstable even though the enthalpy of the latter phase is lower. Some preliminary\nstudies on the growth of the diamond structure starting from a crystal seed\nwere performed. Even though the diamond phase is never thermodynamically stable\nfor the longer-ranged model, direct coexistence simulations of the interface\nbetween the fluid and the body-centred-cubic crystal and between the fluid and\nthe diamond crystal show that, at sufficiently low pressures, it is quite\nprobable that in both cases the solid grows into a diamond crystal, albeit\ninvolving some defects. These results highlight the importance of kinetic\neffects in the formation of diamond crystals in systems of patchy particles."
    },
    {
        "anchor": "Interlayer coupling effect in twisted stacked few layer black phosphorus\n  revealed by abnormal blue shifts in Raman spectra: Twisted stacked few layer black phosphorus heterostructures were successfully\nfabricated in this work. Abnormal blue shifts in their Ag1 and Ag2 Raman peaks\nand unique optical reflections were observed in these samples. The phonon\nbehavior difference can be explained by our density functional theory\ncalculations, which suggest that interlayer coupling has a significant effect\nin twisted bilayer black phosphorus. According to the calculations, the\ninterlayer interactions are not simply van der Waals interactions. Additional\ninteractions, such as weak valence bonding between the top and bottom flakes,\nare considered to be the cause of the blue shifts in their Raman spectra.",
        "positive": "Asymmetric orbital-lattice interactions in ultra-thin correlated oxide\n  films: Using resonant X-ray spectroscopies combined with density functional\ncalculations, we find an asymmetric bi-axial strain-induced $d$-orbital\nresponse in ultra-thin films of the correlated metal LaNiO$_3$ which are not\naccessible in the bulk. The sign of the misfit strain governs the stability of\nan octahedral \"breathing\" distortion, which, in turn, produces an emergent\ncharge-ordered ground state with an altered ligand-hole density and bond\ncovalency. Control of this new mechanism opens a pathway to rational orbital\nengineering, providing a platform for artificially designed Mott materials."
    },
    {
        "anchor": "The use of strain and grain boundaries to tailor phonon transport\n  properties: A first principles study of 2H-phase $CuAlO_{2}$ (Part II): Transparent oxide materials, such as $CuAlO_{2}$, a p-type transparent\nconducting oxide (TCO), have recently been studied for high temperature\nthermoelectric power generators and coolers for waste heat. TCO materials are\ngenerally low cost and non-toxic. The potential to engineer them through strain\nand nano-structuring are two promising avenues toward continuously tuning the\nelectronic and thermal properties to achieve high zT values and low cost/kW-hr\ndevices. In this work, the strain-dependent lattice thermal conductivity of 2H\n$CuAlO_{2}$ is computed by solving the phonon Boltzmann transport equation with\ninteratomic force constants extracted from first-principles calculations. While\nthe average bulk thermal conductivity is around 32 W/(K-m) at room temperature,\nit drops to between 5-15 W/(K-m) for typical experimental grain sizes from 3nm\nto 30nm at room temperature. We find that strain can offer both an increase as\nwell as a decrease in the thermal conductivity as expected, however the overall\ninclusion of small grain sizes dictates the potential for low thermal\nconductivity in this material.",
        "positive": "Screening magnetic two-dimensional atomic crystals with nontrivial\n  electronic topology: To date only a few two-dimensional (2D) magnetic crystals were experimentally\nconfirmed, such as CrI3 and CrGeTe3, all with very low Curie temperatures (TC).\nHigh-throughput first-principles screening over a large set of materials yields\n89 magnetic monolayers including 56 ferromagnetic (FM) and 33 antiferromagnetic\ncompounds. Among them, 24 FM monolayers are promising candidates possessing TC\nhigher than that of CrI3. High TC monolayers with fascinating electronic phases\nare identified: (i) quantum anomalous and valley Hall effects coexist in a\nsingle material RuCl3 or VCl3, leading to a valley-polarized quantum anomalous\nHall state; (ii) TiBr3, Co2NiO6 and V2H3O5 are revealed to be half-metals. More\nimportantly, a new type of fermion dubbed type-II Weyl ring is discovered in\nScCl. Our work provides a database of 2D magnetic materials, which could guide\nexperimental realization of high-temperature magnetic monolayers with exotic\nelectronic states for future spintronics and quantum computing applications."
    },
    {
        "anchor": "Electron Dynamics at High-Energy Densities in Nickel from Non-linear\n  Resonant X-ray Absorption Spectra: The pulse intensity from X-ray free-electron lasers (FELs) can create extreme\nexcitation densities in solids, entering the regime of non-linear X-ray-matter\ninteractions. We show L3-edge absorption spectra of metallic nickel thin films\nwith fluences entering a regime where several X-ray photons are incident per\nabsorption cross-section. Main features of the observed non-linear spectral\nchanges are described with a predictive rate model for electron population\ndynamics during the pulse, utilizing a fixed density of states and tabulated\nground-state properties.",
        "positive": "Cobalt intercalation at the graphene/iridium(111) interface: influence\n  of rotational domains, wrinkles and atomic steps: Using low-energy electron microscopy, we study Co intercalation under\ngraphene grown on Ir(111). Depending on the rotational domain of graphene on\nwhich it is deposited, Co is found intercalated at different locations. While\nintercalated Co is observed preferentially at the substrate step edges below\ncertain rotational domains, it is mostly found close to wrinkles below other\ndomains. These results indicate that curved regions (near substrate atomic\nsteps and wrinkles) of the graphene sheet facilitate Co intercalation and\nsuggest that the strength of the graphene/Ir interaction determines which\npathway is energetically more favorable."
    },
    {
        "anchor": "Generalized dynamics of moving dislocations in quasicrystals: A theoretical framework for dislocation dynamics in quasicrystals is provided\naccording to the continuum theory of dislocations. Firstly, we present the\nfundamental theory for moving dislocations in quasicrystals giving the\ndislocation density tensors and introducing the dislocation current tensors for\nthe phonon and phason fields, including the Bianchi identities. Next, we give\nthe equations of motion for the incompatible elastodynamics as well as for the\nincompatible elasto-hydrodynamics of quasicrystals. We continue with the\nderivation of the balance law of pseudomomentum thereby obtaining the\ngeneralized forms of the Eshelby stress tensor, the pseudomomentum vector, the\ndynamical Peach-Koehler force density and the Cherepanov force density for\nquasicrystals. The form of the dynamical Peach-Koehler force for a straight\ndislocation is obtained as well. Moreover, we deduce the balance law of energy\nthat gives rise to the generalized forms of the field intensity vector and the\nelastic power density of quasicrystals. The above balance laws are produced for\nboth models. The differences between the two models and their consequences are\nrevealed. The influences of the phason fields as well as of the dynamical terms\nare also discussed.",
        "positive": "Coherent Dynamics of Charge Carriers in \u03b3-InSe Revealed by\n  Ultrafast Spectroscopy: For highly efficient ultrathin solar cells, layered indium selenide (InSe), a\nvan der Waals solid, has shown a great promise. In this paper, we study the\ncoherent dynamics of charge carriers generation in {\\gamma}-InSe single\ncrystals. We employ ultrafast transient absorption spectroscopy to examine the\ndynamics of hot electrons after resonant photoexcitation. To study the effect\nof excess kinetic energy of electrons after creating A exciton (VB1 to CB\ntransition), we excite the sample with broadband pulses centered at 600, 650,\n700 and 750 nm, respectively. We analyze the relaxation and recombination\ndynamics in {\\gamma}-InSe by global fitting approach. Five decay associated\nspectra with their associated lifetimes are obtained, which have been assigned\nto intraband vibrational relaxation and interband recombination processes. We\nextract characteristic carrier thermalization times from 1 to 10 ps. To examine\nthe coherent vibrations accompanying intraband relaxation dynamics, we analyze\nthe kinetics by fitting to exponential functions and the obtained residuals are\nfurther processed for vibrational analysis. A few key phonon coherences are\nresolved and ab-initio quantum calculations reveal the nature of the associated\nphonons. The wavelet analysis is employed to study the time evolution of the\nobserved coherences, which show that the low-frequency coherences last for more\nthan 5 ps. Associated calculations reveal that the contribution of the\nintralayer phonon modes is the key determining factor for the scattering\nbetween free electrons and lattice. Our results provide fundamental insights\ninto the photophysics in InSe and help to unravel their potential for\nhigh-performance optoelectronic devices."
    },
    {
        "anchor": "Ferromagnetic resonance spin pumping in CoFeB with highly resistive\n  non-magnetic electrodes: The relative contribution of spin pumping and spin rectification from the\nferromagnetic resonance of CoFeB/non-magnetic bilayers was investigated as a\nfunction of non-magnetic electrode resistance. Samples with highly resistive\nelectrodes of Ta or Ti exhibit a stronger spin rectification signal, which may\nresult in over-(or under-)estimation of the spin Hall angle of the materials,\nwhile those with low resistive electrodes of Pt or Pd show the domination of\nthe inverse spin Hall effect from spin pumping. By comparison with samples of\nsingle FM layer and an inverted structure, we provide a proper analysis method\nto extract spin pumping contribution.",
        "positive": "Correlating atom probe tomography with X-Ray and electron spectroscopies\n  to understand microstructure-activity relationships in electrocatalysts: The search for a new energy paradigm with net-zero carbon emissions requires\nnew technologies for energy generation and storage that are at the crossroad\nbetween engineering, chemistry, physics, surface and materials sciences. To\nkeep pushing the inherent boundaries of device performance and lifetime, we\nneed to step away from a cook-and-look approach and aim to establish the\nscientific ground to guide the design of new materials. This requires strong\nefforts in establishing bridges between microscopy and spectroscopy techniques,\nacross multiple scales. Here, we discuss how the complementarities of X-ray-\nand electron-based spectroscopies and atom probe tomography can be exploited in\nthe study of surfaces and sub-surfaces to understand structure-property\nrelationships in electrocatalysts."
    },
    {
        "anchor": "Energy level alignment at Alq3/La0.7Sr0.3MnO3 interface for organic\n  spintronic devices: The electronic structure of the interface between Tris\n(8-hydroxyquinolino)-aluminum (Alq3) and La0.7Sr0.3MnO3 manganite (LSMO) was\ninvestigated by means of photoelectron spectroscopy. As demonstrated recently\nthis interface is characterized by efficient spin injection in organic\nspintronic devices. We detected a strong interface dipole of about 0.9 eV that\nshifts down the whole energy diagram of the Alq3 with respect to the vacuum\nlevel. This modifies the height of the barriers for the holes injection to 1.7\neV, indicating that hole injection from LSMO into Alq3 is more difficult than\nit was expected as the energy level matched by vacuum levels. We believe the\ninterface dipole is due to the intrinsic dipole moment characteristic for Alq3\nlayer. An additional weak interaction is observed between the two materials\ninfluencing the N 1s core levels of the organic semiconductor. The presented\ndata are of greatest importance for both qualitative and quantitative\ndescription of the organic spin valves.",
        "positive": "In-situ Plasma Studies using a Direct Current Microplasma in a Scanning\n  Electron Microscope: Microplasmas can be used for a wide range of technological applications and\nto improve our understanding of fundamental physics. Scanning electron\nmicroscopy, on the other hand, provides insights into the sample morphology and\nchemistry of materials from the mm-down to the nm-scale. Combining both would\nprovide direct insight into plasma-sample interactions in real-time and at high\nspatial resolution. Up till now, very few attempts in this direction have been\nmade, and significant challenges remain. This work presents a stable direct\ncurrent glow discharge microplasma setup built inside a scanning electron\nmicroscope. The experimental setup is capable of real-time in-situ imaging of\nthe sample evolution during plasma operation and it demonstrates localized\nsputtering and sample oxidation. Further, the experimental parameters such as\nvarying gas mixtures, electrode polarity, and field strength are explored and\nexperimental $V$-$I$ curves under various conditions are provided. These\nresults demonstrate the capabilities of this setup in potential investigations\nof plasma physics, plasma-surface interactions, and materials science and its\npractical applications. The presented setup shows the potential to have several\ntechnological applications, e.g., to locally modify the sample surface (e.g.,\nlocal oxidation and ion implantation for nanotechnology applications) on the\n$\\mu$m-scale."
    },
    {
        "anchor": "Radiation defects in BaF$_2$-Cd: Radiation defects in barium fluoride single crystals doped with cadmium have\nbeen investigated by luminescence and absorption spectroscopy, as well as by\nelectron spin resonance spectroscopy. Three types of Cd$^+$ centers differing\nby the local environment with the point symmetries O$_h$, C$_3$$_v$ and\nC$_2$$_v$ have been identified although in the crystals only the cubic centers\nare usually formed. We believe that these features may arise from the\ndifference in the spacial distribution of the impurities in the crystals.",
        "positive": "Efficient GW calculations in two dimensional materials through a\n  stochastic integration of the screened potential: Many-body perturbation theory methods, such as the $G_0W_0$ approximation,\nare able to accurately predict quasiparticle (QP) properties of several classes\nof materials. However, the calculation of the QP band structure of\ntwo-dimensional (2D) semiconductors is known to require a very dense BZ\nsampling, due to the sharp $q$-dependence of the dielectric matrix in the\nlong-wavelength limit ($\\mathbf{q} \\to 0$). In this work, we show how the\nconvergence of the QP corrections of 2D semiconductors with respect to the BZ\nsampling can be drastically improved, by combining a Monte Carlo integration\nwith an interpolation scheme able to represent the screened potential between\nthe calculated grid points. The method has been validated by computing the band\ngap of three different prototype monolayer materials: a transition metal\ndichalcogenide (MoS$_2$), a wide band gap insulator (hBN) and an anisotropic\nsemiconductor (phosphorene). The proposed scheme shows that the convergence of\nthe gap for these three materials up to 50meV is achieved by using $\\k$-point\ngrids comparable to those needed by DFT calculations, while keeping the grid\nuniform."
    },
    {
        "anchor": "Optical and Acoustic Phonons in Turbostratic and Cubic Boron Nitride\n  Thin Films on Diamond Substrates: We report an investigation of the bulk optical, bulk acoustic, and surface\nacoustic phonons in thin films of turbostratic boron nitride (t-BN) and cubic\nboron nitride (c-BN) grown on B-doped polycrystalline and single-crystalline\ndiamond (001) and (111) substrates. The characteristics of different types of\nphonons were determined using Raman and Brillouin-Mandelstam light scattering\nspectroscopies. The atomic structure of the films was determined using\nhigh-resolution transmission electron microscopy (HRTEM) and correlated with\nthe Raman and Brillouin-Mandelstam spectroscopy data. The HRTEM analysis\nrevealed that the cubic boron nitride thin films consisted of a mixture of c-BN\nand t-BN phases, with c-BN being the dominant phase. It was found that while\nvisible Raman spectroscopy provided information for characterizing the t-BN\nphase, it faced challenges in differentiating the c-BN phase either due to the\npresence of high-density defects or the overlapping of the Raman features with\nthose from the B-doped diamond substrates. In contrast, Brillouin-Mandelstam\nspectroscopy clearly distinguishes the bulk longitudinal and surface acoustic\nphonons of the c-BN thin films grown on diamond substrates. Additionally, the\nangle-dependent surface Brillouin-Mandelstam scattering data show the peaks\nassociated with the Rayleigh surface acoustic waves, which have higher phase\nvelocities in c-BN films on diamond (111) substrates. These findings provide\nvaluable insights into the phonon characteristics of the c-BN and diamond\ninterfaces and have important implications for the thermal management of\nelectronic devices based on ultra-wide-band-gap materials.",
        "positive": "First-principles study of the inversion thermodynamics and electronic\n  structure of Fe$M_2X_4$ (thio)spinels ($M=$ Cr, Mn, Co, Ni; $X=$ O, S): Fe$M_2X_4$ spinels, where $M$ is a transition metal and $X$ is oxygen or\nsulfur, are candidate materials for spin filters, one of the key devices in\nspintronics. We present here a computational study of the inversion\nthermodynamics and the electronic structure of these (thio)spinels for $M=$ Cr,\nMn, Co, Ni, using calculations based on the density functional theory with\non-site Hubbard corrections (DFT+$U$). The analysis of the configurational free\nenergies shows that different behaviour is expected for the equilibrium cation\ndistributions in these structures: FeCr$_2X_4$ and FeMn$_2$S$_4$ are fully\nnormal, FeNi$_2X_4$ and FeCo$_2$S$_4$ are intermediate, and FeCo$_2$O$_4$ and\nFeMn$_2$O$_4$ are fully inverted. We have analyzed the role played by the size\nof the ions and by the crystal field stabilization effects in determining the\nequilibrium inversion degree. We also discuss how the electronic and magnetic\nstructure of these spinels is modified by the degree of inversion, assuming\nthat this could be varied from the equilibrium value. We have obtained\nelectronic densities of states for the completely normal and completely inverse\ncation distribution of each compound. FeCr$_2X_4$, FeMn$_2X_4$, FeCo$_2$O$_4$\nand FeNi$_2$O$_4$ are half-metals in the ferrimagnetic state when Fe is in\ntetrahedral positions. When $M$ is filling the tetrahedral positions, the\nCr-containing compounds and FeMn$_2$O$_4$ are half-metallic systems, while the\nCo and Ni spinels are insulators. The Co and Ni sulfide counterparts are\nmetallic for any inversion degree together with the inverse FeMn$_2$S$_4$. Our\ncalculations suggest that the spin filtering properties of the Fe$M_2X_4$\n(thio)spinels could be modified via the control of the cation distribution\nthrough variations in the synthesis conditions."
    },
    {
        "anchor": "Martensitic relief observation by atomic force microscopy in yttria\n  stabilized zirconia: The tetragonal to monoclinic (t-m) phase transformation of zirconia has been\nthe object of extensive investigations of the last twenty years, and is now\nrecognised as being of martensitic nature. However, martensitic transformation\nhas only been observed by transmission electron microscopy or indirect methods.\nThough the benefit on the fracture toughness and crack resistance was the main\ninterest, the transformation is now considered for its consequences on the\ndegradation of the material. The use of AFM reported here allowed the\nobservation of the first stages of martensite relief growth and of new\nmartensitic features.",
        "positive": "Room-Temperature Highly-Tunable Coercivity and Highly-Efficient\n  Nonvolatile Multi-States Magnetization Switching by Small Current in Single\n  2D Ferromagnet Fe$_3$GaTe$_2$: Room-temperature electrically-tuned coercivity and nonvolatile multi-states\nmagnetization switching is crucial for next-generation low-power 2D\nspintronics. However, most methods have limited ability to adjust the\ncoercivity of ferromagnetic systems, and room-temperature electrically-driven\nmagnetization switching shows high critical current density and high power\ndissipation. Here, highly-tunable coercivity and highly-efficient nonvolatile\nmulti-states magnetization switching are achieved at room temperature in\nsingle-material based devices by 2D van der Waals itinerant ferromagnet\nFe$_3$GaTe$_2$. The coercivity can be readily tuned up to ~98.06% at 300 K by a\ntiny in-plane electric field that is 2-5 orders of magnitude smaller than that\nof other ferromagnetic systems. Moreover, the critical current density and\npower dissipation for room-temperature magnetization switching in 2D\nFe$_3$GaTe$_2$ are down to ~1.7E5 A cm$^{-2}$ and ~4E12 W m$^{-3}$,\nrespectively. Such switching power dissipation is 2-6 orders of magnitude lower\nthan that of other 2D ferromagnetic systems. Meanwhile, multi-states\nmagnetization switching are presented by continuously controlling the current,\nwhich can dramatically enhance the information storage capacity and develop new\ncomputing methodology. This work opens the avenue for room-temperature\nelectrical control of ferromagnetism and potential applications for\nvdW-integrated 2D spintronics."
    },
    {
        "anchor": "Bayesian Optimization of Metastable Nickel Formation During the\n  Spontaneous Crystallization under Extreme Conditions: Spontaneous crystallization of metals under extreme conditions is a unique\nphenomenon occurring under far-from-equilibrium conditions that could enable\nthe development of revolutionary and disruptive metastable metals with unusual\nproperties. In this work, the formation of the hexagonal close-packed Nickel\n(hcp-Ni) metastable phase during spontaneous crystallization is studied using\nnon-equilibrium molecular dynamics (MD) simulations, with the goal of\nmaximizing the fraction of this metastable phase in the final state. We employ\nBayesian Optimization (BO) with the Gaussian Processes (GP) regression as the\nsurrogate model to maximize the hcp-Ni phase fraction, where temperature and\npressure are control variables. MD simulations provide data for training the GP\nmodel, which is then used with BO to predict the next simulation condition.\nSuch a BO-guided active learning leads to a maximum hcp-Ni fraction of 43.38%\nin the final crystalized phase within 40 iterations when a face-centered cubic\n(fcc) crystallite serves as the seed for crystallization from the amorphous\nphase. When an hcp seed is used, the maximum hcp-Ni fraction in the final\ncrystal increases to 58.25% with 13 iterations. This study shows the promise of\nusing BO to identify the process conditions that can maximize the rare phases.\nThis method can also be generally applicable to process optimization to achieve\ntarget material properties.",
        "positive": "Antiferromagnonic Spin Transport from Y$_3$Fe$_5$O$_{12}$ into NiO: We observe highly efficient dynamic spin injection from Y$_3$Fe$_5$O$_{12}$\n(YIG) into NiO, an antiferromagnetic (AF) insulator, via strong coupling, and\nrobust spin propagation in NiO up to 100-nm thickness mediated by its AF spin\ncorrelations. Strikingly, the insertion of a thin NiO layer between YIG and Pt\nsignificantly enhances the spin currents driven into Pt, suggesting\nexceptionally high spin transfer efficiency at both YIG/NiO and NiO/Pt\ninterfaces. This offers a powerful platform for studying AF spin pumping and AF\ndynamics as well as for exploration of spin manipulation in tailored structures\ncomprising metallic and insulating ferromagnets, antiferromagnets and\nnonmagnetic materials."
    },
    {
        "anchor": "Dielectric mixtures -- electrical properties and modeling: In this paper, a review on dielectric mixtures and the importance of the\nnumerical simulations of dielectric mixtures are presented. It stresses on the\ninterfacial polarization observed in mixtures. It is shown that this\npolarization can yield different dielectric responses depending on the\nproperties of the constituents and their concentrations. Open question on the\nsubject are also introduced.",
        "positive": "Dynamic magnetic-transformation-induced exchange bias in\n  (Fe2O3)0.1-(FeTiO3)0.9: Up to now, for the conventional exchange bias (EB) systems there has been one\npinning phase and one pinned phase, and the pinning and pinned phases are\ninherent to the material and do not mutually transform into each other.\nInterestingly, we show here that EB is observed in a special system\n(Fe2O3)0.1(FeTiO3)0.9 (HI9) different from the conventional EB system. Neutron\npowder diffraction and magnetic measurement confirm that for HI9: i) two types\nof short range antiferromagnetic ordering coexist, ii) there are two pinning\nphases and one pinned phase, iii) the pinned phase is not intrinsic to the\nstructure but can be dynamically produced from the pinning phase with the help\nof an external magnetic field. Consequently, two anomalous EB behaviors are\nobserved: i) both the coercivity (HC) and the exchange bias field (HE)\nsimultaneously decrease to zero at 30 K, ii) for a high cooling field (Hcool)\nHE decreases logarithmically with increasing Hcool. Using Arrott plots it is\nconfirmed that the first order magnetic phase transformation (FOMPT) from the\nAFM Fe2+ to ferromagnetic (FM) Fe2+ and the second order magnetic phase\ntransformation (SOMPT) for the process whereby the FM Fe2+ aligns with the\nexternal field direction coexist in HI-9. The Morin transition and FOMPT cause\nthe anomalous EB behaviors. This work may provide fresh ideas for research into\nEB behavior."
    },
    {
        "anchor": "Strain control of magnetic anisotropy in (Ga,Mn)As microbars: We present an experimental and theoretical study of magnetocrystalline\nanisotropies in arrays of bars patterned lithographically into (Ga,Mn)As\nepilayers grown under compressive lattice strain. Structural properties of the\n(Ga,Mn)As microbars are investigated by high-resolution X-ray diffraction\nmeasurements. The experimental data, showing strong strain relaxation effects,\nare in good agreement with finite element simulations. SQUID magnetization\nmeasurements are performed to study the control of magnetic anisotropy in\n(Ga,Mn)As by the lithographically induced strain relaxation of the microbars.\nMicroscopic theoretical modeling of the anisotropy is performed based on the\nmean-field kinetic-exchange model of the ferromagnetic spin-orbit coupled band\nstructure of (Ga,Mn)As. Based on the overall agreement between experimental\ndata and theoretical modeling we conclude that the micropatterning induced\nanisotropies are of the magnetocrystalline, spin-orbit coupling origin.",
        "positive": "First Principles Modeling of the Initial Stages of Organic Solvent\n  Decomposition on Li(x)Mn(2)O(4) (100) Surfaces: Density functional theory and ab initio molecular dynamics simulations are\napplied to investigate the initial steps of ethylene carbonate (EC)\ndecomposition on spinel Li(0.6)Mn(2)O(4) (100) surfaces. EC is a key component\nof the electrolyte used in lithium ion batteries. We predict an slightly\nexothermic EC bond breaking event on this oxide facet, which facilitates\nsubsequent EC oxidation and proton transfer to the oxide surface. Both the\nproton and the partially decomposed EC fragment weaken the Mn-O ionic bonding\nnetwork. Implications for interfacial film made of decomposed electrolyte on\ncathode surfaces, and Li(x)Mn(2)O(4) dissolution during power cycling, are\ndiscussed."
    },
    {
        "anchor": "Magnetic properties of single crystalline itinerant ferromagnet AlFe2B2: Single crystals of AlFe$_{2}$B$_{2}$ have been grown using the self flux\ngrowth method and then measured the structural properties, temperature and\nfield dependent magnetization, and temperature dependent electrical resistivity\nat ambient as well as high pressure. The Curie temperature of AlFe$_{2}$B$_{2}$\nis determined to be $274$~K. The measured saturation magnetization and the\neffective moment for paramagnetic Fe-ion indicate the itinerant nature of the\nmagnetism with a Rhode-Wohlfarth ratio $ \\frac{M_{C}}{M_{sat}}\\approx 1.14$.\nTemperature dependent resistivity measurements under hydrostatic pressure shows\nthat transition temperature \\textit{T$_C$} is suppressed down to 255 K for $p =\n2.24$~GPa pressure with a suppression rate of $\\sim -8.9$~K/GPa. The anisotropy\nfields and magnetocrystalline anisotropy constants are in reasonable agreement\nwith density functional theory calculations.",
        "positive": "Dynamics of Large-Scale Plastic Deformation and the Necking Instability\n  in Amorphous Solids: We use the shear transformation zone (STZ) theory of dynamic plasticity to\nstudy the necking instability in a two-dimensional strip of amorphous solid.\nOur Eulerian description of large-scale deformation allows us to follow the\ninstability far into the nonlinear regime. We find a strong rate dependence;\nthe higher the applied strain rate, the further the strip extends before the\nonset of instability. The material hardens outside the necking region, but the\ndescription of plastic flow within the neck is distinctly different from that\nof conventional time-independent theories of plasticity."
    },
    {
        "anchor": "High mobility in a van der Waals layered antiferromagnetic metal: Magnetic van der Waals (vdW) materials have been heavily pursued for\nfundamental physics as well as for device design. Despite the rapid advances,\nso far magnetic vdW materials are mainly insulating or semiconducting, and none\nof them possesses a high electronic mobility - a property that is rare in\nlayered vdW materials in general. The realization of a magnetic high-mobility\nvdW material would open the possibility for novel magnetic twistronic or\nspintronic devices. Here we report very high carrier mobility in the layered\nvdW antiferromagnet GdTe3. The electron mobility is beyond 60,000 cm2 V-1 s-1,\nwhich is the highest among all known layered magnetic materials, to the best of\nour knowledge. Among all known vdW materials, the mobility of bulk GdTe3 is\ncomparable to that of black phosphorus, and is only surpassed by graphite. By\nmechanical exfoliation, we further demonstrate that GdTe3 can be exfoliated to\nultrathin flakes of three monolayers, and that the magnetic order and\nrelatively high mobility is retained in approximately 20-nm-thin flakes.",
        "positive": "Ferroelectricity of Neel-type magnetic domain walls: The chirality-dependent magnetoelectric properties of Neel-type domain walls\nin iron garnet films is observed. The electrically driven magnetic domain wall\nmotion changes the direction to the opposite with the reversal of electric\npolarity of the probe and with the chirality switching of the domain wall from\nclockwise to counterclockwise. This proves that the origin of the electric\nfield induced micromagnetic structure transformation is inhomogeneous\nmagnetoelectric interaction."
    },
    {
        "anchor": "Ab-initio free energies of liquid metal alloys: application to the phase\n  diagrams of Li-Na and K-Na: Comparison of free energies between different phases and different\ncompositions underlies the prediction of alloy phase diagrams. To allow direct\ncomparison, consistent reference points for the energies or enthalpies are\nrequired, and the entropy must be placed on an absolute scale, yielding\nabsolute free energies. Here we derive absolute free energies of liquids from\nab-initio molecular dynamics (AIMD) by combining the directly simulated\nenthalpies with an entropy derived from simulated densities and pair\ncorrelation functions. As an example of the power of this method we calculate\nthe phase diagrams of two binary alkali metal alloys, Li-Na and K-Na, revealing\na critical point and liquid-liquid phase separation in the former case, and a\ndeep eutectic in the latter. Good agreement with experimental data demonstrates\nthe power of this simple method.",
        "positive": "Trends in the magnetic properties of Fe, Co and Ni clusters and\n  monolayers on Ir(111), Pt(111) and Au(111): We present a detailed theoretical investigation on the magnetic properties of\nsmall single-layered Fe, Co and Ni clusters deposited on Ir(111), Pt(111) and\nAu(111). For this a fully relativistic {\\em ab-initio} scheme based on density\nfunctional theory has been used. We analyse the element, size and geometry\nspecific variations of the atomic magnetic moments and their mutual exchange\ninteractions as well as the magnetic anisotropy energy in these systems. Our\nresults show that the atomic spin magnetic moments in the Fe and Co clusters\ndecrease almost linearly with coordination on all three substrates, while the\ncorresponding orbital magnetic moments appear to be much more sensitive to the\nlocal atomic environment. The isotropic exchange interaction among the cluster\natoms is always very strong for Fe and Co exceeding the values for bulk bcc Fe\nand hcp Co, whereas the anisotropic Dzyaloshinski-Moriya interaction is in\ngeneral one or two orders of magnitude smaller when compared to the isotropic\none. For the magnetic properties of Ni clusters the magnetic properties can\nshow quite a different behaviour and we find in this case a strong tendency\ntowards noncollinear magnetism."
    },
    {
        "anchor": "Nonlocal van der Waals functionals for solids: Choosing an appropriate\n  one: The nonlocal van der Waals (NL-vdW) functionals [Dion et al., Phys. Rev.\nLett. 92, 246401 (2004)] are being applied more and more frequently in\nsolid-state physics, since they have shown to be much more reliable than the\ntraditional semilocal functionals for systems where weak interactions play a\nmajor role. However, a certain number of NL-vdW functionals have been proposed\nduring the last few years, such that it is not always clear which one should be\nused. In this work, an assessment of NL-vdW functionals is presented. Our test\nset consists of weakly bound solids, namely rare gases, layered systems like\ngraphite, and molecular solids, but also strongly bound solids in order to\nprovide a more general conclusion about the accuracy of NL-vdW functionals for\nextended systems. We found that among the tested functionals, rev-vdW-DF2\n[Hamada, Phys. Rev. B 89, 121103(R) (2014)] is very accurate for weakly bound\nsolids, but also quite reliable for strongly bound solids.",
        "positive": "Magnon-drag thermopile: Thermoelectric effects in spintronics are gathering increasing attention as a\nmeans of managing heat in nanoscale structures and of controlling spin\ninformation by using heat flow. Thermal magnons (spin-wave quanta) are expected\nto play a major role, however, little is known about the underlying physical\nmechanisms involved. The reason is the lack of information about magnon\ninteractions and of reliable methods to obtain it, in particular for electrical\nconductors because of the intricate influence of electrons. Here, we\ndemonstrate a conceptually new device that allows us to gather information on\nmagnon-electron scattering and magnon-drag effects. The device resembles a\nthermopile formed by a large number of pairs of ferromagnetic wires placed\nbetween a hot and a cold source and connected thermally in parallel and\nelectrically in series. By controlling the relative orientation of the\nmagnetization in pairs of wires, the magnon-drag can be studied independently\nof the electron and phonon-drag thermoelectric effects. Measurements as a\nfunction of temperature reveal the effect on magnon drag following a variation\nof magnon and phonon populations. This information is crucial to understand the\nphysics of electron-magnon interactions, magnon dynamics and thermal spin\ntransport."
    },
    {
        "anchor": "Propagation of Exchange Bias in CoFe/FeMn/CoFe Trilayers: CoFe/FeMn, FeMn/CoFe bilayers and CoFe/FeMn/CoFe trilayers were grown in\nmagnetic field and at room temperature. The exchange bias field $H_{eb}$\ndepends strongly on the order of depositions and is much higher at CoFe/FeMn\nthan at FeMn/CoFe interfaces. By combining the two bilayer structures into\nsymmetric CoFe/FeMn($t_\\mathrm{FeMn}$)/CoFe trilayers, $H_{eb}^t$ and\n$H_{eb}^b$ of the top and bottom CoFe layers, respectively, are both enhanced.\nReducing $t_\\mathrm{FeMn}$ of the trilayers also results in enhancements of\nboth $H_{eb}^b$ and $H_{eb}^t$. These results evidence the propagation of\nexchange bias between the two CoFe/FeMn and FeMn/CoFe interfaces mediated by\nthe FeMn antiferromagnetic order.",
        "positive": "Optical excitation from anti-causally corrected real-time dynamics in a\n  minimal basis: Here we demonstrate workably accurate estimation of optical excitation\nthreshold for large systems comprising of hundreds of atoms through an\nanti-causally corrected(ACC) real-time dynamics(RTD) approach implemented in a\nminimal tight-binding basis constituted by the directed hybrid atomic Wannier\norbitals. A correction to the Hamiltonian is applied anti-causally at all time\nsteps to account for electron-hole interaction using the density-density\nresponse function. Minimality of basis and ease of transferability of\nparameters to large systems arises from the directed nature of the Wannierized\nhybrid basis orbitals used.With self-energy corrected TB parameters evaluated\nat the DFT + G 0 W 0 level, the proposed ACC-RTD scheme can be systematically\nparametrized to render optical excitation threshold for systems of\nexperimentally realizable length-scales through inexpensive computation."
    },
    {
        "anchor": "First-Principles Study on Preferential Energetics of Mg-based Ternary\n  Alloys Revisited by Short-Range Order in Disordered Phases: To investigate the formation of Mg-based long-period stacking ordered (LPSO)\nstructure, we systematically study the preference of the short-range order\n(SRO) in metastable disordered phases of Mg-RE-Zn (RE = Y, La, Er, Ho, Dy, Tb)\nand Mg-Gd-Al ternary alloy systems through first-principles calculation. RE-Zn\n(RE = Y, Er, Ho, Dy, Tb) and Gd-Al pair clusters' probability showed the\ntendency of increasing. In contrast, La-Zn pair clusters' probability is not\nincreasing, whose system dose not form LPSO structure. This preference of SRO\nin disordered phases of Mg-based ternary alloys certainly indicates that\npeculiar L12-type ordering in LPSO as well as possibility of LPSO formation\nshould have strong correlation with SRO tendency of energetically competitive\ndisordered phases.",
        "positive": "Laser-heated pedestal growth of cerium doped calcium scandate crystal\n  fibers: Ce3+ doped oxide materials are promising for optical emission in the green\nspectral range. The growth of CaSc2O4:Ce3+ single crystals is reported here for\nthe first time. Laser heated pedestal growth (LHPG) proved to be suitable for\nthis refractive material, if performed in nitrogen of 99.999% purity. If the\noxygen content of the growth atmosphere is substantially larger, Ce4+ is\nformed, which shows no useful optical emission. If the oxygen content is\nsubstantially lower, severe evaporation of calcium impedes stable crystal\ngrowth. Thermodynamic equilibrium calculations allowed to describe evaporation\nof species and cerium dopant charging under different growth conditions. The\nevaporation could be investigated by quadrupole mass spectrometry of emanating\ngases and by chemical analysis of fibers with ICP-OES. The congruent melting\npoint was confirmed by DTA at 2110 degrees centigrade. Photoluminescence\nspectrometry of fibers revealed the dependence of optical emission in the green\nspectral range on growth conditions."
    },
    {
        "anchor": "Magneto-optical characterization of MnxGe1-x alloys obtained by ion\n  implantation: Magneto-optical Kerr effect hysteresis loops at various wavelengths in the\nvisible/near-infrared range have been used to characterize the magnetic\nproperties of alloys obtained by implanting Mn ions at fixed energy in a Ge\nmatrix. The details of the hysteresis loops reveal the presence of multiple\nmagnetic contributions. They may be attributed to the inhomogeneous\ndistribution of the magnetic atoms and, in particular, to the known coexistence\nof diluted Mn in the Ge matrix and metallic Mn-rich nanoparticles embedded in\nit [Phys. Rev. B 73, 195207(2006)].",
        "positive": "Highly Conducting Graphene Sheets and Langmuir-Blodgett Films: Graphene is an intriguing material with properties that are distinct from\nthose of other graphitic systems. The first samples of pristine graphene were\nobtained by peeling off and epitaxial growth. Recently, the chemical reduction\nof graphite oxide was used to produce covalently functionalized single-layer\ngraphene oxide. However, chemical approaches for the large-scale production of\nhighly conducting graphene sheets remain elusive. Here, we report that the\nexfoliation-reintercalation-expansion of graphite can produce high-quality\nsingle-layer graphene sheets stably suspended in organic solvents. The graphene\nsheets exhibit high electrical conductance at room and cryogenic temperatures.\nLarge amounts of graphene sheets in organic solvents are made into large\ntransparent conducting films by Langmuir-Blodgett assembly in a layer-by-layer\nmanner. The chemically derived high quality graphene sheets could lead to\nfuture scalable graphene devices."
    },
    {
        "anchor": "Experimental investigation of the softening-stiffening response of\n  tensegrity prisms under compressive loading: The present paper is concerned with the formulation of new assembly methods\nof bi-material tensegrity prisms, and the experimental characterization of the\ncompressive response of such structures. The presented assembly techniques are\neasy to implement, including a string-first approach in the case of ordinary\ntensegrity prisms, and a base-first approach in the case of systems equipped\nwith rigid bases. The experimental section shows that the compressive response\nof tensegrity prisms switches from stiffening to softening under large\ndisplacements, in dependence on the current values of suitable geometric and\nprestress variables. Future research lines regarding the mechanical modeling of\ntensegrity prisms and their use as building blocks of nonlinear periodic\nlattices and acoustic metamaterials are discussed.",
        "positive": "The W center in self-implanted silicon is the self-interstitial cluster\n  I_3: We identify the W center in self-implanted crystalline Si with the\nthree-membered self-interstitial cluster I_3 on the basis of first-principles\ndensity-functional-theory calculations matching all the known experimental\nsignatures of the center (emission energy, extrinsic energy levels, activation\nenergy and dissociation energy, local vibrational structure, and symmetry)."
    },
    {
        "anchor": "First principles calculations of oxygen adsorption on the UN (001)\n  surface: Fabrication, handling and disposal of nuclear fuel materials require\ncomprehensive knowledge of their surface morphology and reactivity. Due to\nunavoidable contact with air components (even at low partial pressures), UN\nsamples contain considerable amount of oxygen impurities affecting fuel\nproperties. The basic properties of O atoms adsorbed on the UN(001) surface are\nsimulated here combining the two first principles calculation methods based on\nthe plane wave basis set and that of the localized atomic orbitals.",
        "positive": "Electronic structure of LaNiO$_{2}$ and CaCuO$_{2}$ from self consistent\n  vertex corrected GW approach: Electronic structure of one of the nickelates (LaNiO$_{2}$) and one of the\ncuprates (CaCuO$_{2}$) is studied with three self consistent GW-based methods:\nscGW, sc(GW+Vertex), and quasiparticle self-consistent GW. Low energy features\nobtained in our study are in many respects similar to the features reported in\nprevious DFT+DMFT studies. Consistent with the DFT+DMFT conclusion, we find\nLaNiO$_{2}$ as more correlated than CaCuO$_{2}$. However, correlation effects\nincluded in our study change the DFT Fermi surface near the $\\Gamma$ point\ndifferently than it was reported in the DMFT studies. Features which are a few\nelectron-volts away from the Fermi level are broader in our calculations than\nin the DFT+DMFT which reflects the differences between the DFT and the GW\nmethods. Our results are in qualitative agreement with previous G0W0 results,\nbut the self-consistency brings in the quantitative differences. Generally,\ncorrelation effects are found to be sufficiently weak in both materials which\nallows one to use totally ab-initio diagrammatic approaches like sc(GW+Vertex)\nand to avoid the methods with adjustable parameters (DFT+U or DFT+DMFT).\nHowever, the possibility of some strong correlations at low energy which cannot\nbe captured by perturbative methods cannot be completely excluded. For\ninstance, differences in the Fermi surface should be resolved: experimental\nstudies are necessary."
    },
    {
        "anchor": "Superconducting $\u03c0$-ring metamaterials: We develop the concept of fractal metamaterials which consist of arrays of\nnano and micron sized rings containing Josephson junctions which play the role\nof \"atoms\" in such artificial materials. We show that if some of the junctions\nhave $\\pi$-shifts in the Josephson phases that the \"atoms\" become magnetic and\ntheir arrays can have tuned positive or negative permeabilty. Each individual\n\"$\\pi$-ring\" - the Josephson ring with one $\\pi$-junction - can be in one of\ntwo energetically degenerate magnetic states in which the supercurrent flows in\nthe clockwise or counter-clockwise direction. This results in magnetic moments\nthat point downwards or upwards, respectively. The value of the total\nmagnetization of such a metamaterial may display fractal features. We describe\nthe magnetic properties of such superconducting metamaterials, including the\nmagnetic field distribution in them (i.e. in the network that is made up of\nthese rings). We also describe the way that the magnetic flux penetrates into\nthe Josephson network and how it is strongly dependent on the geometry of the\nsystem.",
        "positive": "Thermodynamic modeling of the LiF-YF3 phase diagram: A thermodynamic optimization of the LiF-YF3 binary phase diagram was\nperformed by fitting the Gibbs energy functions to experimental data that were\ntaken from the literature, as well as from own thermoanalytic measurements (DTA\nand DSC) on HF-treated samples. The Gibbs energy functions for the end member\ncompounds were taken from the literature. Excess energy terms, which describe\nthe effect of interaction between the two fluoride compounds in the liquid\nphase, were expressed by the Redlich-Kister polynomial function. The calculated\nphase diagram and thermodynamic properties for the unique formed compound,\nLiYF4, are in reasonable agreement with the experimental data."
    },
    {
        "anchor": "Experimental Realization of Type-II Dirac Fermions in PdTe$_2$\n  Superconductor: A Dirac fermion in a topological Dirac semimetal is a quadruple-degenerate\nquasi-particle state with a relativistic linear dispersion. Breaking either\ntime-reversal or inversion symmetry turns this system into a Weyl semimetal\nthat hosts double-degenerate Weyl fermion states with opposite chiralities.\nThese two kinds of quasi-particles, although described by a relativistic Dirac\nequation, do not necessarily obey Lorentz invariance, allowing the existence of\nso-called type-II fermions. Recent theoretical discovery of type-II Weyl\nfermions evokes the prediction of type-II Dirac fermions in PtSe$_2$-type\ntransition metal dichalcogenides, expecting an experimental confirmation. Here,\nwe report an experimental realization of type-II Dirac fermions in PdTe$_2$ by\nangle-resolved photoemission spectroscopy combined with {\\it ab-initio} band\ncalculations. Our experimental finding makes the first example that has both\nsuperconductivity and type-II Dirac fermions, which turns the topological\nmaterial research into a new phase.",
        "positive": "Competing electronic states emerging on polar surfaces: Excess charge on polar surfaces of ionic compounds is commonly described by\nthe two-dimensional electron gas (2DEG) model, a homogeneous distribution of\ncharge, spatially-confined in a few atomic layers. Here, by combining scanning\nprobe microscopy with density functional theory calculations, we show that\nexcess charge on the polar TaO$_2$ termination of KTaO$_3$(001) forms more\ncomplex electronic states with different degrees of spatial and electronic\nlocalization: charge density waves (CDW) coexist with strongly-localized\nelectron polarons and bipolarons. These surface electronic reconstructions,\noriginating from the combined action of electron-lattice interaction and\nelectronic correlation, are energetically more favorable than the 2DEG\nsolution. They exhibit distinct spectroscopy signals and impact on the surface\nproperties, as manifested by a local suppression of ferroelectric distortions.\nControlling the degree of charge ordering and the transition from ferroelectric\nto paraelectric states could be of great benefit for the generation and\ntransport of carriers in electronic applications."
    },
    {
        "anchor": "X-ray diffraction analysis to support phase identification in FeSe and\n  Fe$_7$Se$_8$ epitaxial thin films: X-ray diffraction (XRD) data and analysis for epitaxial iron selenide thin\nfilms grown by pulsed laser deposition (PLD) are presented. The films contain\n${\\beta}$-FeSe and Fe$_7$Se$_8$ phases in a double epitaxy configuration with\nthe ${\\beta}$-FeSe phase (001) oriented on the (001) MgO growth substrate.\nFe$_7$Se$_8$ simultaneously takes on two different epitaxial orientations in\ncertain growth conditions, exhibiting both (101)- and (001)- orientations. Each\nof these orientations are verified with the presented XRD data. Additionally,\nXRD data used to determine the PLD target composition as well as mosaic\nstructure of the ${\\beta}$-FeSe phase are shown.",
        "positive": "Spindle Nodal Chain in Three-Dimensional alpha' Boron: Topological metal/semimetals (TMs) have emerged as a new frontier in the\nfield of quantum materials. A few two-dimensional (2D) boron sheets have been\nsuggested as Dirac materials, however, to date TMs made of three-dimensional\n(3D) boron structures have not been found. Herein, by means of systematic first\nprinciples computations, we discovered that a rather stable 3D boron allotrope,\nnamely 3D-alpha' boron, is a nodal-chain semimetal. In the momentum space, six\nnodal lines and rings contact each other and form a novel spindle nodal chain.\nThis 3D-alpha' boron can be formed by stacking 2D wiggle alpha' boron sheets,\nwhich are also nodal-ring semimetals. In addition, our chemical bond analysis\nrevealed that the topological properties of the 3D and 2D boron structures are\nrelated to the pi bonds between boron atoms, however, the bonding\ncharacteristics are different from those in the 2D and 3D carbon structures."
    },
    {
        "anchor": "RaDMaX online: a web-based program for the determination of strain and\n  damage profiles in irradiated crystals using X-ray diffraction: RaDMaX online is a major update to the previously published RaDMaX (Radiation\nDamage in Materials analysed with X-ray diffraction) software [Souilah, Boulle\n& Debelle, J. Appl. Cryst. (2016) 49, 311-316]. This program features a user\nfriendly interface that allows to retrieve strain and disorder depth-profiles\nin irradiated crystals from the simulation of X-ray diffraction data recorded\nin symmetrical $\\theta/2\\theta$ mode. As compared to its predecessor, RaDMaX\nonline has been entirely rewritten in order to be able to run within a simple\nweb browser, therefore avoiding the necessity to install any programming\nenvironment on the users' computers. The RaDMaX online web-application is\nwritten in Python and developed within a Jupyter notebook implementing\ngraphical widgets and interactive plots. RaDMaX online is free and open source\n(CeCILL license) and can be accessed on the internet at:\nhttps://aboulle.github.io/RaDMaX-online/.",
        "positive": "Anomalous and Planar Nernst effects in thin-films of half-metallic\n  ferromagnet La2/3Sr1/3MnO3: We report the planar and anomalous Nernst effect in epitaxial thin films of\nspin polarized La2/3Sr1/3MnO3. The thermal counterpart of the anomalous Hall\neffect in this material (i.e. the anomalous Nernst effect) shows a extreme\nsensitivity to any parasitic thermal gradient, resulting in large asymmetric\nvoltages under small temperature differences. This should be considered when\ninterpreting the magnitude of the electrical response in nanostructures and\ndevices that operate under high current densities. Finally, none of the\nobserved magneto-thermoelectric signals is compatible with the observation of\nthe Spin Seebeck Effect in this material."
    },
    {
        "anchor": "Hot hole transport and noise phenomena in silicon at cryogenic\n  temperatures from first principles: The transport properties of hot holes in silicon at cryogenic temperatures\nexhibit several anomalous features, including the emergence of two distinct\nsaturated drift velocity regimes and a non-monotonic trend of the current noise\nversus electric field at microwave frequencies. Despite prior investigations,\nthese features lack generally accepted explanations. Here, we examine the\nmicroscopic origin of these phenomena by extending a recently developed\nab-initio theory of high-field transport and noise in semiconductors. We find\nthat the drift velocity anomaly may be attributed to scattering dominated by\nacoustic phonon emission, leading to an additional regime of drift velocity\nsaturation at temperatures $\\sim 40$ K for which the acoustic phonon occupation\nis negligible; while the non-monotonic trend in the current noise arises due to\nthe decrease in momentum relaxation time with electric field. The former\nconclusion is consistent with the findings of prior work, but the latter\ndistinctly differs from previous explanations. This work highlights the use of\nhigh-field transport and noise phenomena as sensitive probes of microscopic\ncharge transport phenomena in semiconductors.",
        "positive": "Properties of $(TiZrNbCu)_{1-x}$$Ni_{x}$ Metallic Glasses: Recent studies (J. Alloys Compd. 695 (2017) 2661) of the electronic structure\nand properties of $(TiZrNbCu)_{1-x}$$Ni_{x}$ (x$\\leq$0.25) amorphous high\nentropy alloys (a-HEA) have been extended to x=0.5 in order to compare\nbehaviours of a-HEA and conventional Ni-base metallic glasses (MG). The\namorphous state of all samples was verified by thermal analysis and X-ray\ndiffraction (XRD). XRD indicated a probable change in local atomic\narrangements, i.e. short-range-order (SRO) for x$\\geq$0.35. Simultaneously,\nthermal parameters, such as the first crystallization temperature $T_{x}$ and\nthe liquidus temperature showed a tendency to saturate for x$\\geq$0.35 . The\nsame tendency also appeared in the magnetic susceptibility $\\chi_{exp}$ and the\nlinear term in the low temperature specific heat {\\gamma}. The Debye\ntemperatures and Youngs moduli also tend to saturate for x$\\geq$0.35. These\nunusual changes in SRO and all properties within the amorphous phase seem\ncorrelated with the change of valence electron number (VEC) on increasing x."
    },
    {
        "anchor": "Efficient Ab Initio Calculations of Electron-Defect Scattering and\n  Defect-Limited Carrier Mobility: Electron-defect ($e$-d) interactions govern charge carrier dynamics at low\ntemperature, where they limit the carrier mobility and give rise to phenomena\nof broad relevance in condensed matter physics. Ab initio calculations of $e$-d\ninteractions are still in their infancy, mainly because they require large\nsupercells and computationally expensive workflows. Here we develop an\nefficient ab initio approach for computing elastic $e$-d interactions, their\nassociated $e$-d relaxation times (RTs), and the low-temperature defect-limited\ncarrier mobility. The method is applied to silicon with simple neutral defects,\nsuch as vacancies and interstitials. Contrary to conventional wisdom, the\ncomputed $e$-d RTs depend strongly on carrier energy and defect type, and the\ndefect-limited mobility is temperature dependent. These results highlight the\nshortcomings of widely employed heuristic models of $e$-d interactions in\nmaterials. Our method opens new avenues for studying $e$-d scattering and\nlow-temperature charge transport from first principles.",
        "positive": "Origin of magnetic interactions and their influence on the structural\n  properties of Ni2MnGa and related compounds: In this work, we perform first principles DFT calculations to investigate the\ninterplay between magnetic and structural properties in Ni2MnGa. We demonstrate\nthat the relative stability of austenite (cubic) and non-modulated martensite\n(tetragonal) phases depends critically on the magnetic interactions between Mn\natoms. While standard approximate DFT functionals stabilize the latter phase, a\nmore accurate treatment of electronic localization and magnetism, obtained with\nDFT+U, suppresses the non-modulated tetragonal structure for the stoichiometric\ncompound, in better agreement with the experiments. We show that the Anderson\nimpurity model, with Mn atoms treated as magnetic impurities, can explain this\nobservation and that the fine balance between super-exchange RKKY type\ninteractions mediated by Ni d and Ga p orbitals determines the equilibrium\nstructure of the crystal. The Anderson model is also demonstrated to capture\nthe effect of the number of valence electrons per unit cell on the structural\nproperties, often used as an empirical parameter to tune the behavior of\nNi2MnGa based alloys. Finally, we show that off-stoichiometric compositions\nwith excess Mn promote transitions to a non-modulated tetragonal structure, in\nagreement with experiments."
    },
    {
        "anchor": "How ripples turn into dots: modeling ion-beam erosion under oblique\n  incidence: Pattern formation on semiconductor surfaces induced by low energetic ion-beam\nerosion under normal and oblique incidence is theoretically investigated using\na continuum model in form of a stochastic, nonlocal, anisotropic\nKuramoto-Sivashinsky equation. Depending on the size of the parameters this\nmodel exhibits hexagonally ordered dot, ripple, less regular and even rather\nsmooth patterns. We investigate the transitional behavior between such states\nand suggest how transitions can be experimentally detected.",
        "positive": "Unifying local and average structure in the phase change material GeTe: The prototypical phase change material GeTe shows an enigmatic phase\ntransition at Tc ca. 650 K from rhombohedral (R3m) to cubic (Fm-3m) symmetry.\nWhile local probes see little change in bonding, in contrast, average structure\nprobes imply a displacive transition. Here we use high energy X-ray scattering\nto develop a model consistent with both the local and average structure\npictures. We detect a correlation length for domains of the R3m structure which\nshows power law decay upon heating. Unlike a classical soft mode, it saturates\nat ca. 20 {\\AA} above Tc. These nanoclusters are too small to be observed by\nstandard diffraction techniques, yet contain the same local motif as the room\ntemperature structure, explaining previous discrepancies. Finally, a careful\nanalysis of the pair distribution functions implies that the 0.6 % negative\nthermal expansion (NTE) at the R3m -Fm-3m transition is associated with the\nloss of coherence between these domains."
    },
    {
        "anchor": "Zr and Sn substituted (NaBi)TiO based solid solutions: Formation of phases during the solid state synthesis of the barium-modified\nNBT solid solutions, with substitutions of zirconium and tin ions for titanium\nare investigated. The synthesis is a multi-step process which is accompanied by\nthe formation of a number of intermediate phases (depending on the solid\nsolution composition and the synthesis temperature). Single phase solid\nsolutions have been manufactured when the sintering temperature was increased\nto 1000-1100 C. An increase of the concentration of the substituting ions\nresults in a linear increase in the size of the crystal cell. As a consequence\nthe reduction of the tolerance factor and an increase of the stability of the\nantiferroelectric phase with respect to the ferroelectric one take place.",
        "positive": "Local atomic structure and discommensurations in the charge density wave\n  of CeTe3: The local structure of CeTe3 in the incommensurate charge density wave\n(IC-CDW) state has been obtained using atomic pair distribution function (PDF)\nanalysis of x-ray diffraction data. Local atomic distortions in the Te-nets due\nto the CDW are larger than observed crystallographically, resulting in distinct\nshort and long Te-Te bonds. Observation of different distortion amplitudes in\nthe local and average structures are explained by the discommensurated nature\nof the CDW since the PDF is sensitive to the local displacements within the\ncommensurate regions whereas the crystallographic result averages over many\ndiscommensurated domains. The result is supported by STM data. This is the\nfirst quantitative local structural study within the commensurate domains in an\nIC-CDW system."
    },
    {
        "anchor": "A learning-based multiscale method and its application to inelastic\n  impact problems: The macroscopic properties of materials that we observe and exploit in\nengineering application result from complex interactions between physics at\nmultiple length and time scales: electronic, atomistic, defects, domains etc.\nMultiscale modeling seeks to understand these interactions by exploiting the\ninherent hierarchy where the behavior at a coarser scale regulates and averages\nthe behavior at a finer scale. This requires the repeated solution of\ncomputationally expensive finer-scale models, and often a priori knowledge of\nthose aspects of the finer-scale behavior that affect the coarser scale (order\nparameters, state variables, descriptors, etc.). We address this challenge in a\ntwo-scale setting where we learn the fine-scale behavior from off-line\ncalculations and then use the learnt behavior directly in coarse scale\ncalculations. The approach draws from recent successes of deep neural networks,\nin combination with ideas from model reduction. The approach builds on the\nrecent success of deep neural networks by combining their approximation power\nin high dimensions with ideas from model reduction. It results in a neural\nnetwork approximation that has high fidelity, is computationally inexpensive,\nis independent of the need for a priori knowledge, and can be used directly in\nthe coarse scale calculations. We demonstrate the approach on problems\ninvolving the impact of magnesium, a promising light-weight structural and\nprotective material.",
        "positive": "Electronic shell structure and chemisorption on gold nanoparticles: We use density functional theory (DFT) to investigate the electronic\nstructure and chemical properties of gold nanoparticles. Different structural\nfamilies of clusters are compared. For up to 60 atoms we optimize structures\nusing DFT-based simulated annealing. Cluster geometries are found to distort\nconsiderably, creating large band gaps at the Fermi level. For up to 200 atoms\nwe consider structures generated with a simple EMT potential and clusters based\non cuboctahedra and icosahedra. All types of cluster geometry exhibit\njellium-like electronic shell structure. We calculate adsorption energies of\nseveral atoms on the cuboctahedral clusters. Adsorption energies are found to\nvary abruptly at magic numbers. Using a Newns-Anderson model we find that the\neffect of magic numbers on adsorption energy can be understood from the\nlocation of adsorbate-induced states with respect to the cluster Fermi level."
    },
    {
        "anchor": "Equilibrium shapes and energies of coherent strained InP islands: The equilibrium shapes and energies of coherent strained InP islands grown on\nGaP have been investigated with a hybrid approach that has been previously\napplied to InAs islands on GaAs. This combines calculations of the surface\nenergies by density functional theory and the bulk deformation energies by\ncontinuum elasticity theory. The calculated equilibrium shapes for different\nchemical environments exhibit the {101}, {111}, {\\=1\\=1\\=1} facets and a (001)\ntop surface. They compare quite well with recent atomic-force microscopy data.\nThus in the InP/GaInP-system a considerable equilibration of the individual\nislands with respect to their shapes can be achieved. We discuss the\nimplications of our results for the Ostwald ripening of the coherent InP\nislands. In addition we compare strain fields in uncapped and capped islands.",
        "positive": "Ab initio investigation of a spin-polarized two-dimensional electron gas\n  at the BaTiO3/LaMnO3 interface: By means of ab initio calculations the possibilities of switchable\nspin-polarized two-dimensional electron gas (2DEG) at the interface of\nantiferromagnetic and ferroelectric perovskites, i.e., LaMnO3/BaTiO3\nsuperlattice, were investigated. We demonstrate that at the heterostructure\nwith TiO2/LaO interfacial layers the two-dimensional conducting state arises\nmainly localized within the interfacial MnO layer. The density of states at the\nFermi-level can be tuned by ferroelectric polarization reversal. The conducting\nstate coexists with magnetic one mainly arose from Mn atoms."
    },
    {
        "anchor": "Polaron-induced band renormalization due to linear and quadratic\n  electron-phonon coupling: We present a novel approach to electron-lattice interaction beyond the\nlinear-coupling regime. Based on the solution of a Holstein-Peierls-type model,\nwe derive explicit analytical expressions for the eigenvalue spectrum of the\nHamiltonian, resulting in a narrowing of bands as a function of temperature.\nOur approach enables the intuitive interpretation in terms of quasiparticles,\ni.e. polaron bands and dressed-phonon frequencies. Being nonperturbative, the\nformalism also applies in the strong-coupling case. We apply it to the organic\ncrystal naphthalene, with the coupling strengths obtained by \\textit{ab initio}\ncalculations.",
        "positive": "Exploring yttrium doped C$_{24}$ fullerene as a high-capacity reversible\n  hydrogen storage material: DFT investigations: By employing the state-of-the-art density functional theory, we report the\nhydrogen storage capability of yttrium decorated C$_{24}$ fullerene. Single Y\natom attached on C$_{24}$ fullerene can reversibly adsorb a maximum number of 6\nH$_2$ molecules with average adsorption energy -0.37 eV and average desorption\ntemperature 477 K, suitable for fuel cell applications. The gravimetric weight\ncontent of hydrogen is 8.84 %, which exceeds the target value of 6.5 wt % H by\nthe department of energy (DoE) of the United States. Y atom is strongly bonded\nto C$_{24}$ fullerene with a binding energy of -3.4 eV due to a charge transfer\nfrom Y-4d and Y-5s orbitals to the C-2p orbitals of C$_{24}$ fullerene. The\ninteraction of H$_2$ molecules with the Y atom is due to the Kubas type\ninteraction involving a charge donation from the metal d orbital to H 1s\norbital, and back donation causing slight elongation of H-H bond length. The\nstability of the system at the highest desorption temperature is confirmed by\nab-initio molecular dynamics simulations, and the metal-metal clustering\nformation has been investigated by computing the diffusion energy barrier for\nthe movement of Y atoms. We have corrected all the calculated energies for the\nvan der Waals (vdW) interactions by applying the dispersion energy corrections,\nin addition to the contribution of the GGA exchange-correlation functional. The\nC$_{24}$+Y system is stable at room temperature, and at the highest desorption\ntemperature, the presence of a sufficient diffusion energy barrier prevents\nmetal-metal clustering. Furthermore, binding energies of H$_2$ are within the\ntarget value by DoE (-0.2-0.7 eV/H$_2$ ), while H$_2$ uptake (8.84 % H) is\nhigher than DoE's criteria. Therefore, we propose that Y decorated C$_{24}$\nfullerene can be tailored as a practically viable potential hydrogen storage\ncandidate."
    },
    {
        "anchor": "Atomic-scale investigation of creep behavior in nanocrystalline Mg and\n  Mg-Y alloys: Magnesium (Mg) and its alloys offer great potential for reducing vehicular\nmass and energy consumption due to their inherently low densities.\nHistorically, widespread applicability has been limited by low strength\nproperties compared to other structural Al-, Ti- and Fe-based alloys. However,\nrecent studies have demonstrated high-specific-strength in a number of\nnanocrystalline Mg-alloys. Even so, applications of these alloys would be\nrestricted to low-temperature automotive components due to microstructural\ninstability under high temperature creep loading. Hence, this work aims to gain\na better understanding of creep and associated deformation behavior of columnar\nnanocrystalline Mg and Mg-yttrium (Y) (up to 3at.%Y(10wt.%Y)) with a grain size\nof 5 nm and 10 nm. Using molecular dynamics (MD) simulations, nanocrystalline\nmagnesium with and without local concentrations of yttrium is subjected to\nconstant-stress loading ranging from 0 to 500 MPa at different initial\ntemperatures ranging from 473 to 723 K. In pure Mg, the analyses of the\ndiffusion coefficient and energy barrier reveal that at lower temperatures\n(i.e., T < ~423K) the contribution of grain boundary diffusion to the overall\ncreep deformation is stronger that the contribution of lattice diffusion.\nHowever, at higher temperatures (T > ~423K) lattice diffusion dominates the\noverall creep behavior. Interestingly, for the first time, we have shown that\nthe(101-1),(101-2),(101-3) and (101-6) boundary sliding energy is reduced with\nthe addition of yttrium. This softening effect in the presence of yttrium\nsuggests that the experimentally observed high temperature beneficial effects\nof yttrium addition is likely to be attributed to some combination of other\nreported creep strengthening mechanisms or phenomena such as formation of\nstable yttrium oxides at grain boundaries or increased forest dislocation-based\nhardening.",
        "positive": "Theory of thermostatted inhomogeneous granular fluids: a self-consistent\n  density functional description: The authors present a study of the non equilibrium statistical properties of\na one dimensional hard-rod fluid dissipating energy via inelastic collisions\nand subject to the action of a Gaussian heat bath, simulating an external\ndriving mechanism. They show that the description of the fluid based on the\none-particle phase-space reduced distribution function, in principle necessary\nbecause of the presence of velocity dependent collisional dissipation, can be\ncontracted to a simpler description in configurational space. Indeed, by means\nof a multiple-time scale method the authors derive a self-consistent governing\nequation for the particle density distribution function. This equation is\nsimilar to the dynamic density functional equation employed in the study of\ncolloids, but contains additional terms taking into account the inelastic\nnature of the fluid. Such terms cannot be derived from a Liapunov generating\nfunctional and contribute not only to the relaxational properties, but also to\nthe non equilibrium steady state properties. A validation of the theory against\nmolecular dynamics simulations is presented in a series of cases, and good\nagreement is found."
    },
    {
        "anchor": "Structural Modificationand Variation in the Kinetics of Isoconversional\n  Phenomena: A Study on the Effect of Gamma Irradiation on Poly (Ethylene\n  Oxide): Interactions of Poly (Ethylene Oxide) [PEO] and gamma irradiation of variable\ndoses (1-30 kGy) on the thermal, crystalline and structural properties are\ninvestigated using DSC and FTIR technique. Two states of PEO, viz. powder\n(P-S-series) and solution (P-L-series) are subjected to irradiationand are\ncastinto uniform film.DSC results revealed steady increment of crystallinity\nupto 20 kGy for P-S-series after which amorphous region increases till 30 kGy.\nConversely, P-L-series shows much enhanced crystallinity retained within low\nregime of 7 kGy, followed by sharp declining trend till 30 kGy. DSC is also\nused to determine the multiple kinetic processes in an isoconversional PEO\nmelting using Friedman differential analysis. Gamma irradiation is found to\ngenerate newer functional groups established from FTIR study. FTIR spectra of\ngenerated peaks viz. -C=O, -C=C- exhibit scission dominated irradiation induced\nin presence of air. Contribution of cross-linkage which is higher in liquid\nirradiation is also proved from FTIR. The studied observations of DSC and FTIR\nare correlated with polymer microstructures. Hence, selective irradiation dose\ncould be determined with respect to the exposed state (solid or solution) of\npolymer and utilized to tailor the properties of PEO.",
        "positive": "Uniform materials and the multiplicative decomposition of the\n  deformation gradient in finite elasto-plasticity: In this work we analyze the relation between the multiplicative decomposition\n$\\mathbf F=\\mathbf F^{e}\\mathbf F^{p}$ of the deformation gradient as a product\nof the elastic and plastic factors and the theory of uniform materials. We\nprove that postulating such a decomposition is equivalent to having a uniform\nmaterial model with two configurations - total $\\phi$ and the inelastic\n$\\phi_{1}$. We introduce strain tensors characterizing different types of\nevolutions of the material and discuss the form of the internal energy and that\nof the dissipative potential. The evolution equations are obtained for the\nconfigurations $(\\phi,\\phi_{1})$ and the material metric $\\mathbf g$.\n  Finally the dissipative inequality for the materials of this type is\npresented.It is shown that the conditions of positivity of the internal\ndissipation terms related to the processes of plastic and metric evolution\nprovide the anisotropic yield criteria."
    },
    {
        "anchor": "Revealing nanoscale disorder in W/CoFeB/MgO ultra-thin films using\n  domain wall motion: Disorder in ultra-thin magnetic films can significantly hinder domain wall\nmotion. One of the main issues on the path towards efficient domain wall based\ndevices remains the characterization of the pinning landscape at the nanoscale.\nIn this paper, we study domain wall motion in W/CoFeB/MgO thin films with\nperpendicular magnetic anisotropy crystallized by annealing at 400$^{\\circ}$C\nand a process based on He$^{+}$ irradiation combined with elevated\ntemperatures. Magnetic properties are similar for the whole series of samples,\nwhile the magnetic domain wall mobility is critically improved in the\nirradiated samples. By using an analytical model to extract nanoscale pinning\nparameters, we reveal important variations in the disorder of the crystallized\nsamples. This work offers a unique opportunity to selectively analyze the\neffects of disorder on the domain wall dynamics, without the contribution of\nchanges in the magnetic properties. Our results highlight the importance of\nevaluating the nanoscale pinning parameters of the material when designing\ndevices based on domain wall motion, which in return can be a powerful tool to\nprobe the disorder in ultra-thin magnetic films.",
        "positive": "Coherent imaging and dynamics of excitons in MoSe$_2$ monolayers\n  epitaxially grown on hexagonal boron nitride: Using four-wave mixing microscopy, we measure the coherent response and\nultrafast dynamics of excitons and trions in MoSe$_2$ monolayers grown by\nmolecular beam epitaxy on thin films of hexagonal boron nitride. We assess\ninhomogeneous and homogeneous broadenings in the transition spectral lineshape.\nThe impact of phonons on the homogeneous dephasing is inferred via the\ntemperature dependence of the dephasing. Four-wave mixing mapping, combined\nwith the atomic force microscopy, reveals spatial correlations between exciton\noscillator strength, inhomogeneous broadening and the sample morphology. The\nquality of coherent optical response of the epitaxially grown transition metal\ndichalcogenides becomes now comparable with the samples produced by mechanical\nexfoliation, enabling coherent nonlinear spectroscopy of innovative materials,\nlike magnetic layers or Janus semiconductors."
    },
    {
        "anchor": "Large spin Hall magnetoresistance and its correlation to the spin-orbit\n  torque in W/CoFeB/MgO structures: The spin-orbit interaction in heavy metal/ferromagnet/oxide structures has\nbeen extensively investigated because it can be employed in manipulation of the\nmagnetization direction by in-plane current. This implies the existence of an\ninverse effect, in which the conductivity in such structures should depend on\nthe magnetization orientation. In this work, we report a systematic study of\nthe magnetoresistance (MR) of the W/CoFeB/MgO structures and its correlation to\nthe current-induced torque to the magnetization. We observe that the MR is\nindependent of the angle between magnetization and current direction, but is\ndetermined by the relative magnetization orientation with respect to the spin\ndirection accumulated by spin Hall effect, which is the same symmetry of\nso-called spin Hall magnetoresistance. The MR of ~1% in W/CoFeB/MgO samples is\nconsiderably larger than those in other structures of Ta/CoFeB/MgO or\nPt/Co/AlOx, which indicates a larger spin Hall angle of W. Moreover, the\nsimilar W thickness dependence of the MR and the current-induced magnetization\nswitching efficiency demonstrates that they share the same underlying physics,\nwhich allows one to utilize the MR in non-magnet/ferromagnet structure in order\nto understand closely related other spin-orbit coupling effects such as inverse\nspin Hall effect, spin-orbit spin transfer torques, etc.",
        "positive": "Bulk moduli of PbS$_{x}$Se$_{1-x}$, PbS$_{x}$Te$_{1-x}$, and\n  PbSe$_{x}$Te$_{1-x}$ from the combination of the $cB\u03a9$ model with the\n  modified Born theory compared to generalized gradient approximation: The bulk moduli of PbS$_{x}$Se$_{1-x}$, PbS$_{x}$Te$_{1-x}$, and\nPbSe$_{x}$Te$_{1-x}$ have been recently determined [E. Skordas, Materials\nScience in Semiconductor Processing 43 (2016) 65-68] by employing a\nthermodynamical model, the so called $cB\\Omega$ model, which has been found to\ngive successful results in several applications of defects in solids. Here, we\nsuggest an alternative procedure for this determination which combines the\n$cB\\Omega$ model with the modified Born theory. The results are in satisfactory\nagreement with those deduced independently by the generalized gradient\napproximation approach."
    },
    {
        "anchor": "Structural Diversity in Lithium Carbides: The lithium-carbon binary system possesses a broad range of chemical\ncompounds, which exhibit fascinating chemical bonding characteristics that give\nrise diverse and technologically important properties. While lithium carbides\nwith various compositions have been studied or suggested previously, the\ncrystal structures of these compounds are far from well understood. In this\nwork we present the first comprehensive survey of all ground state (GS)\nstructures of lithium carbides over a broad range of thermodynamic conditions,\nusing \\textit{ab initio} density functional theory (DFT) crystal structure\nsearching methods. Thorough searches were performed for 29 stoichiometries\nranging from Li$_{12}$C to LiC$_{12}$ at 0 GPa as well as 40 GPa. Based on\nformation enthalpies from optimized van der Waals density functional\ncalculations, three thermodynamically stable phases (Li$_4$C$_3$, Li$_2$C$_2$\nand LiC$_{12}$) were identified at 0 GPa, and seven thermodynamically stable\nphases (Li$_8$C, Li$_6$C, Li$_4$C, Li$_8$C$_3$, Li$_2$C, Li$_3$C$_4$, and\nLi$_2$C$_3$) were predicted at 40 GPa. A rich diversity of carbon bonding,\nincluding monomers, dimers, trimers, nanoribbons, sheets and frameworks, was\nfound within these structures, and the dimensionality of carbon connectivity\nexisting within each phase was observed to increase with increasing carbon\nconcentration. Of particular interest, we find that the well-known composition\nLiC$_6$ is actually a metastable one. We also find a unique coexistence of\ncarbon monomers and dimers within the predicted thermodynamically stable phase\nLi$_8$C$_3$, and different widths of carbon nanoribbons coexist in a metastable\nphase of Li$_2$C$_2$ (\\textit{Imm}2). Interesting mixed\n\\textit{sp}$^2$-\\textit{sp}$^3$ carbon frameworks are predicted in metastable\nphases with composition LiC$_6$.",
        "positive": "Phase transitions in inorganic halide perovskites from machine learning\n  potentials: The atomic scale dynamics of halide perovskites have a direct impact not only\non their thermal stability but their optoelectronic properties. Progress in\nmachine learned potentials has only recently enabled modeling the finite\ntemperature behavior of these material using fully atomistic methods with near\nfirst-principles accuracy. Here, we systematically analyze the impact of\nheating and cooling rate, simulation size, model uncertainty, and the role of\nthe underlying exchange-correlation functional on the phase behavior of CsPbX3\nwith X=Cl, Br, and I, including both the perovskite and the delta-phases. We\nshow that rates below approximately 30 K/ns and system sizes of at least a few\nten thousand atoms are indicated to achieve convergence with regard to these\nparameters. By controlling these factors and constructing models that are\nspecific for different exchange-correlation functionals we then show that the\nsemi-local functionals considered in this work (SCAN, vdW-DF-cx, PBEsol, and\nPBE) systematically underestimate the transition temperatures separating the\nperovskite phases while overestimating the lattice parameters. Among the\nconsidered functionals the vdW-DF-cx functional yields the closest agreement\nwith experiment, followed by SCAN, PBEsol, and PBE. Our work provides\nguidelines for the systematic analysis of dynamics and phase transitions in\ninorganic halide perovskites and similar systems. It also serves as a benchmark\nfor the further development of machine-learned potentials as well as\nexchange-correlation functionals."
    },
    {
        "anchor": "Structure and dielectric properties of Ba$_2$Cu$_x$Y$_{1-x}$TaO$_{6-y}$\n  double perovskite: In this paper, we reported the effect of Cu doping on the structural and\ndielectric properties of Ba$_2$Y$_{1-x}$Cu$_x$TaO$_{6-y}$ (0.00 $\\leq$ x $\\leq$\n0.50) ceramics at room temperature. The Copper for Yttrium substitution reduces\nthe sintering temperature and leads to structural changes in the Ba$_2$YTaO$_6$\nrock-salt crystalline structure. Dielectric permittivity and complex impedance\nspectroscopy measurements suggested enhancement of the dielectric constant and\noccurrence of interfacial Maxwell-Wagner polarization.",
        "positive": "Investigation of n-type dilute magnetic semiconductor property observed\n  in amorphous AlNO alloy thin film incorporated with dilute nitrogen at 300K: In the present work, a thin film was deposited on quartz substrate by\nreactive RF magnetron sputtering of high purity (99.999%) aluminium target\nusing ultra-high pure (Ar + N2) gas mixture. The percentage ratio of Ar and N2\nin the gas mixture was 95% and 5%, respectively. Chemical characterization\nusing x-ray photoelectron spectroscopy (XPS) and energy-dispersive xray (EDX)\nspectroscopy reveals that in the presence of dilute nitrogen, Al prefers to\nreact with residual oxygen to form Al2O3 while the nitrogen is incorporated in\nit. The stoichiometry of bulk film is Al2N0.38O3.1. Magnetic and electrical\nproperties measurement shows that the film exhibits ntype dilute magnetic\nsemiconductor (DMS) property at 300K. The film has low electrical resistivity\nof 6.3 {\\Omega}-cm and high carrier mobility of 5.7*106 cm2V-1s-1 at 300K. A\ndensity functional theory (DFT) calculation was performed to investigate the\norigin of observed magnetism in the film. From first-principles calculation\nbased on DFT, it is found that for thermodynamic stability dilute nitrogen\nincorporated in Al2O3 preferred to sit at the interstitial site, which is\nresponsible for observed magnetic property. Present study reported here\nprovides a new insight to prepare rarely observed n-type DMS at room\ntemperature by incorporating nitrogen interstitials in Al2O3, which is\ndesirable for potential application in the field of spintronics."
    },
    {
        "anchor": "Sub-nanosecond delay of light in (Cd,Zn)Te crystal: We study excitonic polariton relaxation and propagation in bulk CdZnTe using\ntime- resolved photoluminescence and time-of-flight techniques. Propagation of\npicosecond optical pulses through 0.745 mm thick crystal results in time delays\nup to 350 ps, depending on the photon energy. Optical pulses with 150 fs\nduration become strongly stretched. The spectral dependence of group velocity\nis consistent with the dispersion of the lower excitonic polariton branch. The\nlifetimes of excitonic polariton in the upper and lower branches are 1.5 and 3\nns, respectively.",
        "positive": "Exotic Node Line in ternary MgSrSi-type crystals: Node line (NL) band-touchings protected by mirror symmetry (named as $m$-NL),\nthe product of inversion and time reversal symmetry $\\mathcal{S=PT}$ ($s$-NL),\nor nonsymmorphic symmetry are nontrivial topological objects of topological\nsemimetals (SMs) in the Brillouin Zone (BZ). In this work, we screened the\nfamily of MgSrSi-type crystals using first principles calculations, and\ndiscovered that more than 70 members are NLSMs. A new type of multi-loop\nstructure was found in AsRhTi that a $s$-NL touches robustly with a $m$-NL at\nsome \"nexus point\", and in the meanwhile a second $m$-NL crosses with the\n$s$-NL to form a Hopf-link. Unlike the previously proposed Hopf-link formed by\ntwo $s$-NLs or two $m$-NLs, a Hopf-link formed by a $s$-NL and a $m$-NL\nrequires a minimal three-band model to characterize its essential electronic\nstructure. The associated topological surface states on different surfaces of\nAsRhTi crystal were also obtained. Even more complicated and exotic multi-loop\nstructure of NLs were predicted in AsFeNa and PNiNb. Our work may shed light on\nsearch for exotic multi-loop NLSMs in real materials."
    },
    {
        "anchor": "Single-axis dependent structural and multiferroic properties of\n  orthorhombic RMnO$_3$ (R = Gd - Lu): Controlling material properties by modulating the crystalline structure has\nbeen attempted using various techniques, e.g., hydrostatic pressure, chemical\npressure, and epitaxy. These techniques succeed to improve properties and\nachieve desired functionalities by changing the unit cell in all dimensions. In\norder to obtain a more detailed understanding on the relation between the\ncrystal lattice and material properties, it is desirable to investigate the\ninfluence of a smaller number of parameters. Here, we utilize the combination\nof chemical pressure and epitaxy to modify a single lattice parameter of the\nmultiferroic orthorhombic RMnO$_3$ (R = rare-earth, o-RMnO$_3$) system. By\ngrowing a series of o-RMnO$_3$ (R = Gd - Lu) films coherently on (010)-oriented\nYAlO$_3$ substrates, the influence of chemical pressure is reflected only along\nthe $b$-axis. Thus, a series of o-RMnO$_3$ with $a$ ~ 5.18 {\\AA}, 5.77 {\\AA} <\n$b$ < 5.98 {\\AA}, and $c$ ~ 7.37 {\\AA} were obtained. Raman spectra analysis\nreveals that the change of the $b$-axis parameter induces a shift of the oxygen\nin the nominally \"fixed\" $ca$-plane. Their ferroelectric ground state is\nindependent on the $b$-axis parameter showing polarization of ~ 1 $\\mu$C\ncm$^{-2}$ along the $a$-axis for the above-mentioned range, except for $b$ ~\n5.94 {\\AA} which corresponds to TbMnO$_3$ showing ~ 2 $\\mu$C cm$^{-2}$. This\nresult implies that multiferroic order of o-RMnO$_3$ is almost robust against\nthe $b$-axis parameter provided that the dimension of the $ca$-plane is fixed\nto 7.37 {\\AA} $\\times$ 5.18 {\\AA}.",
        "positive": "Internal magnetic fields in thin ZnSe epilayers: Strain induced spin-splitting is observed and characterized using pump-probe\nKerr rotation spectroscopy in n-ZnSe epilayers grown on GaAs substrates. The\nspin-splitting energies are mapped out as a function of pump-probe separation,\napplied voltage, and temperature in a series of samples of varying epilayer\nthicknesses and compressive strain arising from epilayer-substrate lattice\nmismatch. The strain is independently quantified using photoluminescence and\nx-ray diffraction measurements. We observe that the magnitude of the spin\nsplitting increases with applied voltage and temperature, and is highly crystal\ndirection dependent, vanishing along [1 1-bar 0]."
    },
    {
        "anchor": "Symmorphic intersecting nodal rings in semiconducting layers: The unique properties of topological semimetals have strongly driven efforts\nto seek for new topological phases and related materials. Here, we identify a\ncritical condition for the existence of linked nodal rings (LNRs) in symmorphic\ncrystals, and propose that three types of LNRs, named as alpha-, beta- and\ngamma-type, can be obtained by stacking semiconducting layers. Several\nhoneycomb structures are suggested to be topological LNR semimetals, including\nlayered and \"hidden\" layered structures. Transitions between the three types of\nLNRs can be driven by external strains. Interesting surface states other than\ndrumhead states are found in these topological materials.",
        "positive": "Ultralong carrier lifetime of topological edge states in a-Bi4Br4: The rising of quantum spin Hall insulators (QSHI) in two-dimensional (2D)\nsystems has been attracting significant interest in current research, for which\nthe 1D helical edge states, a hallmark of QSHI, are widely expected to be a\npromising platform for next-generation optoelectronics. However, the dynamics\nof the 1D edge states has not yet been experimentally addressed. Here, we\nreport the observation of optical response of the topological helical edge\nstates in a-Bi4Br4, using the infrared-pump infrared-probe microscopic\nspectroscopy. Remarkably, we observe that the carrier lifetime of the helical\nedge states reaches nanosecond-scale at room temperature, which is about 2 - 3\norders longer than that of most 2D topological surface states and is even\ncomparable with that of the well developed optoelectronics semiconductors used\nin modern industry. The ultralong carrier lifetime of the topological edge\nstates may be attributed to their helical and 1D nature. Our findings not only\nprovide an ideal material for further investigations of the carrier dynamics of\n1D helical edge states but also pave the way for its application in\noptoelectronics."
    },
    {
        "anchor": "Arrays of widely spaced atomic steps on Si(111) mesas due to sublimation: Steps with spacings of microns form on top of mesas fabricated on Si(111)\nthat is annealed at temperatures where sublimation becomes important. Upon\nannealing, mesas first develop ridges along their edges, effectively creating\ncraters which then become step-free by a step flow process described in the\nliterature. Due to the miscut of the average surface from (111), ridge\nbreakdown occurs on one edge of each mesa as sublimation proceeds. The\nbreakdown point then acts as a source of steps which spread out over the mesa\nsurface. The distribution of steps in the resulting step train depends on the\nsublimation rate, direct step-step interaction and the diffusive exchange of\natoms among the steps. Computer simulations using BCF (Burton, Cabrera and\nFrank) theory provide insight into the controlling processes. The results\nsuggest that self-organization of the wide terrace distributions in the low\nstep density area occurs under sublimation. We compare the experimental and\npredicted step distributions.",
        "positive": "Probing Emergent Surface and Interfacial Properties in Complex Oxides\n  via in situ X-ray Photoelectron Spectroscopy: Emergent behavior at complex oxide interfaces has driven much of the research\nin the oxide thin film community for the past twenty years. Interfaces have\nbeen engineered for potential applications in spintronics, topological quantum\ncomputing, and high-speed electronics in cases where the bulk materials would\nnot exhibit the desired properties. Advances in thin film growth have made the\nsynthesis of these interfaces possible, while surface characterization tools\nsuch as X-ray photoelectron spectroscopy have been critical to understanding\nsurface and interfacial phenomena in these materials. In this review we discuss\nthe leading research in the oxide field over the past 5-10 years with a focus\non connecting the key results to the X-ray photoelectron spectroscopy studies\nthat enabled them. We describe how in situ integration of synthesis and\nspectroscopy can be used to improve the film growth process and to perform\nimmediate experiments on specifically tailored interfacial heterostructures.\nThese studies can include determination of interfacial intermixing, valence\nband alignment, and interfacial charge transfer. We also show how advances in\nsynchrotron-based spectroscopy techniques have answered questions that cannot\nbe addressed in a lab-based system. By further tying together synthesis and\nspectroscopy through in situ techniques, we conclude by discussing future\nopportunities in the field through the careful design of thin film\nheterostructures that are optimized for X-ray studies."
    },
    {
        "anchor": "Macroscopic polarization and band offsets at nitride heterojunctions: Ab initio electronic structure studies of prototypical polar interfaces of\nwurtzite III-V nitrides show that large uniform electric fields exist in\nepitaxial nitride overlayers, due to the discontinuity across the interface of\nthe macroscopic polarization of the constituent materials. Polarization fields\nforbid a standard evaluation of band offsets and formation energies: using new\ntechniques, we find a large forward-backward asymmetry of the offset (0.2 eV\nfor AlN/GaN (0001), 0.85 eV for GaN/AlN (0001)), and tiny interface formation\nenergies.",
        "positive": "Compression of Wannier functions into Gaussian-type orbitals: We propose a greedy algorithm for the compression of Wannier functions into\nGaussian-polynomials orbitals. The so-obtained compressed Wannier functions can\nbe stored in a very compact form, and can be used to efficiently parameterize\neffective tight-binding Hamiltonians for multilayer 2D materials for instance.\nThe compression method preserves the symmetries (if any) of the original\nWannier function. We provide algorithmic details, and illustrate the\nperformance of our implementation on several examples, including graphene,\nhexagonal boron-nitride, single-layer FeSe, and bulk silicon in the diamond\ncubic structure."
    },
    {
        "anchor": "First-Principles Wannier Functions of Silicon and Gallium Arsenide: We present a self-consistent, real-space calculation of the Wannier functions\nof Si and GaAs within density functional theory. We minimize the total energy\nfunctional with respect to orbitals which behave as Wannier functions under\ncrystal translations and, at the minimum, are orthogonal. The Wannier functions\nare used to calculate the total energy, lattice constant, bulk modulus, and the\nfrequency of the zone-center TO phonon of the two semiconductors with the\naccuracy required nowadays in ab-initio calculations. Furthermore, the centers\nof the Wannier functions are used to compute the macroscopic polarization of Si\nand GaAs in zero electric field. The effective charges of GaAs, obtained by\nfinite differentiation of the polarization, agree with the results of linear\nresponse theory.",
        "positive": "Magnetism of mixed quaternary Heusler alloys: (Ni,T)$_{2}$MnSn (T=Cu,Pd)\n  as a case study: The electronic properties, exchange interactions, finite-temperature\nmagnetism, and transport properties of random quaternary Heusler Ni$_{2}$MnSn\nalloys doped with Cu- and Pd-atoms are studied theoretically by means of {\\it\nab initio} calculations over the entire range of dopant concentrations. While\nthe magnetic moments are only weakly dependent on the alloy composition, the\nCurie temperatures exhibit strongly non-linear behavior with respect to\nCu-doping in contrast with an almost linear concentration dependence in the\ncase of Pd-doping. The present parameter-free theory agrees qualitatively and\nalso reasonably well quantitatively with the available experimental results. An\nanalysis of exchange interactions is provided for a deeper understanding of the\nproblem. The dopant atoms perturb electronic structure close to the Fermi\nenergy only weakly and the residual resistivity thus obeys a simple Nordheim\nrule. The dominating contribution to the temperature-dependent resistivity is\ndue to thermodynamical fluctuations originating from the spin-disorder, which,\naccording to our calculations, can be described successfully via the disordered\nlocal moments model. Results based on this model agree fairly well with the\nmeasured values of spin-disorder induced resistivity."
    },
    {
        "anchor": "Approaches for Uncertainty Quantification of AI-predicted Material\n  Properties: A Comparison: The development of large databases of material properties, together with the\navailability of powerful computers, has allowed machine learning (ML) modeling\nto become a widely used tool for predicting material performances. While\nconfidence intervals are commonly reported for such ML models, prediction\nintervals, i.e., the uncertainty on each prediction, are not as frequently\navailable. Here, we investigate three easy-to-implement approaches to determine\nsuch individual uncertainty, comparing them across ten ML quantities spanning\nenergetics, mechanical, electronic, optical, and spectral properties.\nSpecifically, we focused on the Quantile approach, the direct machine learning\nof the prediction intervals and Ensemble methods.",
        "positive": "Lateral diffusive spin transport in layered structures: A one dimensional theory of lateral spin-polarized transport is derived from\nthe two dimensional flow in the vertical cross section of a stack of\nferromagnetic and paramagnetic layers. This takes into account the influence of\nthe lead on the lateral current underneath, in contrast to the conventional 1D\nmodeling by the collinear configuration of lead/channel/lead. Our theory is\nconvenient and appropriate for the current in plane configuration of an\nall-metallic spintronics structure as well as for the planar structure of a\nsemiconductor with ferromagnetic contacts. For both systems we predict the\noptimal contact width for maximal magnetoresistance and propose an electrical\nmeasurement of the spin diffusion length for a wide range of materials."
    },
    {
        "anchor": "Temporal and Thermal Stability of Al2O3-passivated Phosphorene MOSFETs: This letter evaluates temporal and thermal stability of a state-of-the-art\nfew-layer phosphorene MOSFET with Al2O3 surface passivation and Ti/Au top gate.\nAs fabricated, the phosphorene MOSFET was stable in atmosphere for at least 100\nh. With annealing at 200{\\deg}C in dry nitrogen for 1 h, its drain current\nincreased by an order of magnitude to approximately 100 mA/mm, which could be\nattributed to the reduction of trapped charge in Al2O3 and/or Schottky barrier\nat the source and drain contacts. Thereafter, the drain current was stable\nbetween -50{\\deg}C and 150{\\deg}C up to at least 1000 h. These promising\nresults suggest that environmental protection of phosphorene should not be a\nmajor concern, and passivation of phosphorene should focus on its effect on\nelectronic control and transport as in conventional silicon MOSFETs. With\ncutoff frequencies approaching the gigahertz range, the present phosphorene\nMOSFET, although far from being optimized, can meet the frequency and stability\nrequirements of most flexible electronics for which phosphorene is\nintrinsically advantageous due to its corrugated lattice structure.",
        "positive": "Strain relaxation models: A review of the approaches to numerical description of strain relaxation in\nthin films during epitaxial growth of heterostructures"
    },
    {
        "anchor": "Failure of the Maxwell relation for the quantification of caloric\n  effects in ferroic materials: Giant caloric effects were reported in elasto-, electro- and magnetocaloric\nmaterials near phase transformations. Commonly, their entropy change is\nindirectly evaluated by a Maxwell relation. We report the fundamental failure\nof this approach. We analyze exemplarily the Ni-Mn-Ga magnetic shape memory\nalloy. An applied field results in magnetically induced reorientation of\nmartensitic variants, which form during the phase transformation. This results\nin a spurious magnetocaloric effect, which only disappears when repeating the\nmeasurement a second time. This failure is universal as the vector character of\nthe applied field is not considered in the common scalar evaluation of a\nMaxwell relation.",
        "positive": "Simulated sulfur K-edge X-ray absorption spectroscopy database of\n  lithium thiophosphate solid electrolytes: X-ray absorption spectroscopy (XAS) is a premier technique for materials\ncharacterization, providing key information about the local chemical\nenvironment of the absorber atom. In this work, we develop a database of sulfur\nK-edge XAS spectra of crystalline and amorphous lithium thiophosphate materials\nbased on the atomic structures reported in Chem. Mater., 34, 6702 (2022). The\nXAS database is based on simulations using the excited electron and core-hole\npseudopotential approach implemented in the Vienna Ab initio Simulation\nPackage. Our database contains 2681 S K-edge XAS spectra for 66 crystalline and\nglassy structure models, making it the largest collection of first-principles\ncomputational XAS spectra for glass/ceramic lithium thiophosphates to date.\nThis database can be used to correlate S spectral features with distinct S\nspecies based on their local coordination and short-range ordering in\nsulfide-based solid electrolytes. The data is openly distributed via the\nMaterials Cloud, allowing researchers to access it for free and use it for\nfurther analysis, such as spectral fingerprinting, matching with experiments,\nand developing machine learning models."
    },
    {
        "anchor": "Comment on: Synthesis, growth and characterization of a new metal\n  organic Nlo material: Dibromo bis(L proline)Cd(II): The title paper by Boopathi and Ramasamy reports a study on the crystal\ngrowth and characterization of dibromobis (L-proline)Cd(II) (1). Many points of\ncriticism, concerning the crystal structure of (1) and the magnetic properties\nof (1) dibromo bis(L-proline)Zn(II) (2) and diiodo bis(2-aminopyridine)Cd(II)\n(3) are reported to show that compounds 1 to 3 are not soft magnets but instead\ndiamagnetic solids.",
        "positive": "Spin-polaron formation and magnetic state diagram in La doped $CaMnO_3$: $La_xCa_{1-x}MnO_3$ (LCMO) has been studied in the framework of density\nfunctional theory (DFT) using Hubbard-U correction. We show that the formation\nof spin-polarons of different configurations is possible in the G-type\nantiferromagentic phase. We also show that the spin-polaron (SP) solutions are\nstabilized due to an interplay of magnetic and lattice effects at lower La\nconcentrations and mostly due to the lattice contribution at larger\nconcentrations. Our results indicate that the development of SPs is unfavorable\nin the C- and A-type antiferromagnetic phases. The theoretically obtained\nmagnetic state diagram is in good agreement with previously reported\nexperimental results"
    },
    {
        "anchor": "The role of atomic orbitals of doped earth-abundant metals on designed\n  copper catalytic surfaces: It is a general challenge to design highly active or selective earth-abundant\nmetals for catalytic hydrogenation. Here, we demonstrated an effective\ncomputational approach based on inverse molecular design theory to\ndeterministically search for optimal binding sites on Cu (100) surface through\nthe doping of Fe and/or Zn, and a stable Zn-doped Cu (100) surface was found\nwith minimal binding energy to H-atoms. We analyze the electronic structure\ncause of the optimal binding sites using a new quantum chemistry method called\norbital-specific binding energy analysis. Compared to the 3d-orbitals of\nsurface Cu atoms, the 3d-orbitals of surface Zn-atoms show less binding energy\ncontribution and participation, and are much less influenced by the electronic\ncouplings of the media Cu atoms. Our study provides valuable green chemistry\ninsights on designing catalysts using earth-abundant metals, and may lead to\nthe development of novel Cu-based earth-abundant alloys for important catalytic\nhydrogenation applications such as lignin degradation or CO2 transformation.",
        "positive": "Temperature dependence of electric resistance and magnetoresistance of\n  pressed nanocomposites of multilayer nanotubes with the structure of nested\n  cones: Bulk samples of carbon multilayer nanotubes with the structure of nested\ncones (fishbone structure) suitable for transport measurements, were prepared\nby compressing under high pressure (~25 kbar) a nanotube precursor synthesized\nthrough thermal decomposition of polyethylene catalyzed by nickel. The\nstructure of the initial nanotube material was studied using high-resolution\ntransmission electron microscopy. In the low-temperature range (4.2 - 100 K)\nthe electric resistance of the samples changes according to the law ln \\rho ~\n(T_0/T)^{1/3}, where T_0 ~ 7 K. The measured magnetoresistance is quadratic in\nthe magnetic field and linear in the reciprocal temperature. The measurements\nhave been interpreted in terms of two-dimensional variable-range hopping\nconductivity. It is suggested that the space between the inside and outside\nwalls of nanotubes acts as a two-dimensional conducting medium. Estimates\nsuggest a high value of the density of electron states at the Fermi level of\nabout 5 10^{21} eV^{-1} cm^{-3}."
    },
    {
        "anchor": "First-principles study of the effects of electron-phonon coupling on the\n  thermoelectric properties: a case study of SiGe compound: It is generally assumed in the thermoelectric community that the lattice\nthermal conductivity of a given material is independent of the electronic\nproperties. This perspective is however questionable since the electron-phonon\ncoupling could have certain effects on both the carrier and phonon transport,\nwhich in turn will affect the thermoelectric properties. Using SiGe compound as\na prototypical example, we give an accurate prediction of the carrier\nrelaxation time by considering scattering from all the phonon modes, as opposed\nto the simple deformation potential theory. It is found that the carrier\nrelaxation time does not change much with the concentration, which is however\nnot the case for the phonon transport where the lattice thermal conductivity\ncan be significantly reduced by electron-phonon coupling at higher carrier\nconcentration. As a consequence, the figure-of-merit of SiGe compound is\nobviously enhanced at optimized carrier concentration, and becomes more\npronounced at elevated temperature.",
        "positive": "Large barocaloric effect with high pressure-driving efficiency in\n  hexagonal MnNi0.77Fe0.23Ge alloy: The hydrostatic pressure is expected to be an effective knob to tune the\nmagnetostructural phase transitions of hexagonal MMX alloy. In this study,\nmagnetization measurements under hydrostatic pressure were performed on a MMX\nmartensitic MnNi0.77Fe0.23Ge alloy. The magnetostructural transition\ntemperature can be efficiently tuned to lower temperatures by applying moderate\npressures, with a giant shift rate of -151 K GPa-1. A temperature span of 30 K\nis obtained under the pressure, within which a large magnetic entropy change of\n-23 J kg-1 K-1 in a field change of 5 T is induced by the mechanical energy\ngain due to the large volume change. Meanwhile, a decoupling of structural and\nmagnetic transitions is observed at low temperatures when the martensitic\ntransition temperature is lower than the Curie temperature. These results show\na multi-parameter tunable caloric effect that benefits the solid-state cooling."
    },
    {
        "anchor": "Element selection for functional materials discovery by integrated\n  machine learning of elemental contributions to properties: Fundamental differences between materials originate from the unique nature of\ntheir constituent chemical elements. Before specific differences emerge\naccording to the precise ratios of elements in a given crystal structure, a\nmaterial can be represented by the set of its constituent chemical elements. By\nworking at the level of the periodic table, assessment of materials at the\nlevel of their phase fields reduces the combinatorial complexity to accelerate\nscreening, and circumvents the challenges associated with composition-level\napproaches such as poor extrapolation within phase fields, and the\nimpossibility of exhaustive sampling. This early stage discrimination combined\nwith evaluation of novelty of phase fields aligns with the outstanding\nexperimental challenge of identifying new areas of chemistry to investigate, by\nprioritising which elements to combine in a reaction. Here, we demonstrate that\nphase fields can be assessed with respect to the maximum expected value of a\ntarget functional property and ranked according to chemical novelty. We develop\nand present PhaseSelect, an end-to-end machine learning model that combines the\nrepresentation, classification, regression and ranking of phase fields. First,\nPhaseSelect constructs elemental characteristics from the co-occurrence of\nchemical elements in computationally and experimentally reported materials,\nthen it employs attention mechanisms to learn representation for phase fields\nand assess their functional performance. At the level of the periodic table,\nPhaseSelect quantifies the probability of observing a functional property,\nestimates its value within a phase field and also ranks a phase field novelty,\nwhich we demonstrate with significant accuracy for three avenues of materials\napplications for high-temperature superconductivity, high-temperature\nmagnetism, and targeted bandgap energy.",
        "positive": "Ab initio study of compressed Ar(H2)2: structural stability and\n  anomalous melting: We study the structural stability and dynamical properties of Ar(H2)2 under\npressure using first-principles and ab initio molecular dynamics techniques. At\nlow temperatures, Ar(H2)2 is found to stabilize in the cubic C15 Laves\nstructure (MgCu2) and not in the hexagonal C14 Laves structure (MgZn2) as it\nhas been assumed previously. Based on enthalpy energy and phonon calculations,\nwe propose a temperature-induced MgCu2 -> MgZn2 phase transition that may\nrationalize the existing discrepancies between the sets of Raman and infrared\nvibron measurements. Our AIMD simulations suggest that the melting line of\nAr(H2)2 presents negative slope in the interval 60 < P < 110 GPa. We explain\nthe origin of this intriguing physical phenomenon in terms of decoupling of the\nAr and H2 degrees of freedom and effective thermal-like excitations arising\nfrom coexisting liquid H2 and solid Ar phases."
    },
    {
        "anchor": "Umklapp Scattering and Heat Conductivity of Superlattices: The mean free path of phonons in superlattices is estimated. It is shown to\nbe strongly dependent on the superlattice period due to the Umklapp scattering\nin subbands. It first falls with increasing the superlattice period until it\nbecomes comparable with the latter after what it rises back to the bulk value.\nSimilar behavior is expected of heat conductivity, which is proportional to the\nmean free path.",
        "positive": "Observation of an Abrupt 3D-2D Morphological Transition in Thin Al\n  Layers Grown by MBE on InGaAs surface: Among superconductor/semiconductor hybrid structures, in-situ aluminum (Al)\ngrown on InGaAs/InAs is widely pursued for the experimental realization of\nMajorana Zero Mode quasiparticles. This is due to the high carrier mobility,\nlow effective mass, and large Land\\'e g-factor of InAs, coupled with the\nrelatively high value of the in-plane critical magnetic field in thin Al films.\nHowever, growing a thin, continuous Al layer using the Molecular Beam Epitaxy\n(MBE) is challenging due to aluminum's high surface mobility and tendency for\n3D nucleation on semiconductor surfaces. A study of epitaxial Al thin film\ngrowth on In0.75Ga0.25As with MBE is presented, focusing on the effects of the\nAl growth rate and substrate temperature on the nucleation of Al layers. We\nfind that for low deposition rates, 0.1 {\\AA}/s and 0.5 {\\AA}/s, the growth\ncontinues in 3D mode during the deposition of the nominal 100 {\\AA} of Al,\nresulting in isolated Al islands. However, for growth rates of 1.5 {\\AA}/s and\nabove, the 3D growth mode quickly transitions into island coalescence, leading\nto a uniform 2D Al layer. Moreover, this transition is very abrupt, happening\nover an Al flux increase of less than 1%. We discuss the growth mechanisms\nexplaining these observations. The results give new insights into the kinetics\nof Al deposition and show that with sufficiently high Al flux, a 2D growth on\nsubstrates at close to room temperature can be achieved already within the\nfirst few Al monolayers. This eliminates the need for complex cryogenic\nsubstrate cooling and paves the way for the development of high-quality\nsuperconductor-semiconductor interfaces in standard MBE systems."
    },
    {
        "anchor": "Unfolding spinor wavefunctions and expectation values of general\n  operators: Introducing the unfolding-density operator: We show that the spectral weights $W_{m\\vec K}(\\vec k)$ used for the\nunfolding of two-component spinor eigenstates $| {\\psi_{m\\vec K}^\\mathrm{SC}} >\n= | \\alpha > | {\\psi_{m\\vec{K}}^\\mathrm{SC, \\alpha}} > + | \\beta > |\n{\\psi_{m\\vec{K}}^\\mathrm{SC, \\beta}} >$ can be decomposed as the sum of the\npartial spectral weights $W_{m\\vec{K}}^{\\mu}(\\vec k)$ calculated for each\ncomponent $\\mu = \\alpha, \\beta$ independently, effortlessly turning a possibly\ncomplicated problem involving two coupled quantities into two independent\nproblems of easy solution. Furthermore, we define the unfolding-density\noperator $\\hat{\\rho}_{\\vec{K}}(\\vec{k}_{i}; \\, \\varepsilon)$, which unfolds the\nprimitive cell expectation values $\\varphi^{pc}(\\vec{k}; \\varepsilon)$ of any\narbitrary operator $\\mathbf{\\hat\\varphi}$ according to\n$\\varphi^{pc}(\\vec{k}_{i}; \\varepsilon) =\n\\mathit{Tr}(\\hat{\\rho}_{\\vec{K}}(\\vec{k}_{i}; \\,\n\\varepsilon)\\,\\,\\hat{\\varphi})$. As a proof of concept, we apply the method to\nobtain the unfolded band structures, as well as the expectation values of the\nPauli spin matrices, for prototypical physical systems described by\ntwo-component spinor eigenfunctions.",
        "positive": "Atomically Sharp 318nm Gd:AlGaN Ultraviolet Light Emitting Diodes on Si\n  with Low Threshold Voltage: Self assembled AlGaN polarization-induced nanowire light emitting diodes\n(PINLEDs) with Gd-doped AlN active regions are prepared by plasma-assisted\nmolecular beam epitaxy on Si substrates. Atomically sharp electroluminescence\n(EL) from Gd intra-f-shell electronic transitions at 313 nm and 318 nm are\nobserved under forward biases above 5V. The intensity of the Gd 4f EL scales\nlinearly with current density and increases at lower temperature. The low\nelectric field excitation of Gd 4f EL in PINLEDs is contrasted with high field\nexcitation in Gd:AlGaN MIS nanowire devices (metal/Gd:AlN/polarization induced\nn-AlGaN) where it is concluded that PINLED devices offer over a three fold\nenhancement in 4f EL intensity at a given device bias."
    },
    {
        "anchor": "Multi-objective Bayesian optimization of ferroelectric materials with\n  interfacial control for memory and energy storage applications: Optimization of materials performance for specific applications often\nrequires balancing multiple aspects of materials functionality. Even for the\ncases where generative physical model of material behavior is known and\nreliable, this often requires search over multidimensional parameter space to\nidentify low-dimensional manifold corresponding to required Pareto front. Here\nwe introduce the multi-objective Bayesian Optimization (MOBO) workflow for the\nferroelectric/anti-ferroelectric performance optimization for memory and energy\nstorage applications based on the numerical solution of the Ginzburg-Landau\nequation with electrochemical or semiconducting boundary conditions. MOBO is a\nlow computational cost optimization tool for expensive multi-objective\nfunctions, where we update posterior surrogate Gaussian process models from\nprior evaluations, and then select future evaluations from maximizing an\nacquisition function. Using the parameters for a prototype bulk\nantiferroelectric (PbZrO3), we first develop a physics-driven decision tree of\ntarget functions from the loop structures. We further develop a physics-driven\nMOBO architecture to explore multidimensional parameter space and build\nPareto-frontiers by maximizing two target functions jointly: energy storage and\nloss. This approach allows for rapid initial materials and device parameter\nselection for a given application and can be further expanded towards the\nactive experiment setting. The associated notebooks provide both the tutorial\non MOBO and allow to reproduce the reported analyses and apply them to other\nsystems (https://github.com/arpanbiswas52/MOBO_AFI_Supplements).",
        "positive": "Transient Hydrodynamic Lattice Cooling by Picosecond Laser Irradiation\n  of Graphite: Recent theories and experiments have suggested hydrodynamic phonon transport\nfeatures in graphite at unusually high temperatures. Here, we report a\npico-second pump-probe thermal reflectance measurement of heat pulse\npropagation in graphite. The measurement results reveal transient lattice\ncooling near the adiabatic center of a 15 $\\mu$m diameter ring-shape pump beam\nat temperatures between 80 and 120 K. While such lattice cooling has not been\nreported in recent diffraction measurements of second sound in graphite, the\nobservation here is consistent with both hydrodynamic phonon transport theory\nand prior heat pulse measurements of second sound in bulk sodium fluoride."
    },
    {
        "anchor": "Detection of the spin character of Fe(001) surface states by scanning\n  tunneling microscopy: A theoretical proposal: We consider the magnetic structure on the Fe(001) surface and theoretically\nstudy the scanning tunneling spectroscopy using a spin-polarized tip (SP-STM).\nWe show that minority-spin surface states induce a strong bias dependence of\nthe tunneling differential conductance which largely depends on the orientation\nof the magnetization in the SP-STM tip relative to the easy magnetization axis\nin the Fe(001) surface. We propose to use this effect in order to determine the\nspin character of the Fe(001) surface states. This technique can be applied\nalso to other magnetic surfaces in which surface states are observed.",
        "positive": "Magnetism of Al$_x$Fe$_{2-x}$GeO$_5$ with Andalusite Structure: The magnetism of Al$_x$Fe$_{2-x}$GeO$_5$ from $x$ = 0.09 to $x$ = 0.91 with\nandalusite structure was examined. The magnetic properties of\nAl$_x$Fe$_{2-x}$GeO$_5$ at low temperatures were found to be weak\nferromagnetic-like state for $x$ $<$ 0.3 and spin-glass state for $x$ $>$ 0.3.\nThe small spontaneous magnetization that appears in the weak ferromagnetic-like\nphase would be due to the presence of Dzyaloshinsky-Moriya interaction or to\nthe difference in the magnitude of the magnetic moment of Fe$^{3+}$ in the\noctahedral and trigonal bipyramidal sites. The appearance of the spin-glass\nphase indicates that the dilution of Fe ions by Al ions in\nAl$_x$Fe$_{2-x}$GeO$_5$ causes the competition between ferromagnetic and\nantiferromagnetic interactions. The $x$ dependence of the site occupancy of Fe\nions suggests that Fe$_2$GeO$_5$ with andalusite structure cannot be\nsynthesized."
    },
    {
        "anchor": "Simplified Bond Hyperpolarizability Model of Second Harmonic Generation,\n  Group Theory and Neumann's Principle: We discuss the susceptibility third-rank tensor for second harmonic and\nsumfrequency generation, associated with low index surfaces of silicon\n(Si(001), Si(011) and Si(111)) from two different approaches: the Simplified\nBond-Hyperpolarizablility Model(SBHM) and Group Theory (GT). We show that SBHM\nagrees very well with the experimental results for simple surfaces because the\ndefinitions of the bond vectors implicitly include the geometry of the crystal\nand therefore the symmetry group. However, for more complex surfaces it is\nshown that one can derive from GT the SBHM tensor, if Kleinman symmetry is\nallowed.",
        "positive": "Direct atomistic modeling of solute drag by moving grain boundaries: We show that molecular dynamics (MD) simulations are capable of reproducing\nthe drag of solute segregation atmospheres by moving grain boundaries (GBs).\nAlthough lattice diffusion is frozen out on the MD timescale, the accelerated\nGB diffusion provides enough atomic mobility to allow the segregated atoms to\nfollow the moving GB. This finding opens the possibility of studying the solute\ndrag effect with atomic precision using the MD approach. We demonstrate that a\nmoving GB activates diffusion and alters the short-range order in the lattice\nregions swept during its motion. It is also shown that a moving GB drags an\natmosphere of non-equilibrium vacancies, which accelerate diffusion in\nsurrounding lattice regions."
    },
    {
        "anchor": "Domain wall motion in epitaxial Pb(Zr,Ti)O3 capacitors investigated by\n  modified piezoresponse force microscopy: We investigated the time-dependent domain wall motion of epitaxial\nPbZr0.2Ti0.8O3 capacitors 100 nm-thick using modified piezoresponse force\nmicroscopy (PFM). We obtained successive domain evolution images reliably by\ncombining the PFM with switching current measurements. We observed that domain\nwall speed (v) decreases with increases in domain size. We also observed that\nthe average value of v, obtained under applied electric field (Eapp),showed\ncreep behavior: i.e. <v> ~ exp(-E0/Eapp)^$\\mu$ with an exponent $\\mu$ of 0.9\n$\\pm$ 0.1 and an activation field E0 of about 700 kV/cm.",
        "positive": "Topologically stable bimerons and skyrmions in vanadium dichalcogenide\n  Janus monolayers: We investigate the magnetic phase diagram of 1T-vanadium dichalcogenide\nmonolayers in Janus configuration (VSeTe, VSSe, and VSTe) from first\nprinciples. The magnetic exchange, magnetocrystalline anisotropy and\nDzyaloshinskii-Moriya interaction (DMI) are computed using density functional\ntheory calculations, while the temperature- and field-dependent magnetic phase\ndiagram is simulated using large-scale atomistic spin modeling in the presence\nof thermal fluctuations. The boundaries between magnetic ordered phases and\nparamagnetic phases are determined by cross-analyzing the average topological\ncharge with the magnetic susceptibility and its derivatives. We find that in\nsuch Janus monolayers, DMI is large enough to stabilize non-trivial chiral\ntextures. In VSeTe monolayer, an asymmetrical bimeron lattice state is\nstabilized for in-plane field configuration whereas skyrmion lattice is formed\nfor out-of-plane field configuration. In VSSe monolayer, a skyrmion lattice is\nstabilized for out-of-plane field configuration. This study demonstrates that\nnon-centrosymmetric van der Waals magnetic monolayers can support topological\ntextures close to room temperature."
    },
    {
        "anchor": "Characterization methods dedicated to nanometer-thick hBN layers: Hexagonal boron nitride (hBN) regains interest as a strategic component in\ngraphene engineering and in van der Waals heterostructures built with two\ndimensional materials. It is crucial then, to handle reliable characterization\ntechniques capable to assess the quality of structural and electronic\nproperties of the hBN material used. We present here characterization\nprocedures based on optical spectroscopies, namely cathodoluminescence and\nRaman, with the additional support of structural analysis conducted by\ntransmission electron microscopy. We show the capability of optical\nspectroscopies to investigate and benchmark the optical and structural\nproperties of various hBN thin layers sources.",
        "positive": "Mechanical properties of cubic boron nitride and diamond at dynamical\n  pressure and temperature: We report the mechanical properties of cubic boron nitride (c-BN) and diamond\nunder the combined impact of dynamical pressure and temperature, calculated\nusing ab initio molecular dynamics. Our study revealed a pronounced sensitivity\nof the mechanical properties of c-BN to applied pressure. Notably, c-BN\nundergoes a brittle-to-ductile transition at ~220 GPa, consistent across\nvarious dynamical temperatures, while diamond exhibits no such transition.\nFurthermore, the Vickers hardness profile for c-BN closely mirrors that of\ndiamond across a spectrum of temperature-pressure conditions, highlighting\nc-BN's significant mechanical robustness. These results underscore the superior\nresilience and adaptability of c-BN compared to diamond, suggesting its\npotential as an ideal candidate for applications in extreme environments."
    },
    {
        "anchor": "Two-dimensional metallic ferroelectricity in PbTe monolayer by\n  electrostatic doping: Polar metals characterized by the simultaneous coexistence of ferroelectric\ndistortions and metallicity have attracted tremendous attention. Developing\nsuch materials at low dimensions remains challenging since both conducting\nelectrons and reduced dimensions are supposed to quench ferroelectricity. Here,\nbased on first-principles calculations, we report the discovery of\nferroelectric behavior in two-dimensional (2D) metallic materials with\nelectrostatic doping, even though ferroelectricity is unconventional at the\natomic scale. We reveal that PbTe monolayer is intrinsic ferroelectrics with\npronounced out-of-plane electric polarization originated from its\nnon-centrosymmetric buckled structure. The ferroelectric distortions can be\npreserved with carriers doping in the ferroelectric monolayer, which thus\nenables the doped PbTe monolayer to act as a 2D polar metal. With an effective\nHamiltonian extracted from the parametrized energy space, we found that the\nelastic-polar mode interaction is of great importance for the existence of\nrobust polar instability in the doped system. The application of this doping\nstrategy is not specific to the present crystal, but is rather general to other\n2D ferroelectrics to bring about the fascinating metallic ferroelectric\nproperties. Our findings thus change conventional acknowledge in 2D materials\nand will facilitate the development of multifunctional material in low\ndimensions.",
        "positive": "Panoramic mapping of phonon transport from ultrafast electron\n  diffraction and machine learning: One central challenge in understanding phonon thermal transport is a lack of\nexperimental tools to investigate mode-based transport information. Although\nrecent advances in computation lead to mode-based information, it is hindered\nby unknown defects in bulk region and at interfaces. Here we present a\nframework that can reveal microscopic phonon transport information in\nheterostructures, integrating state-of-the-art ultrafast electron diffraction\n(UED) with advanced scientific machine learning. Taking advantage of the dual\ntemporal and reciprocal-space resolution in UED, we are able to reliably\nrecover the frequency-dependent interfacial transmittance with possible\nextension to frequency-dependent relaxation times of the heterostructure. This\nenables a direct reconstruction of real-space, real-time, frequency-resolved\nphonon dynamics across an interface. Our work provides a new pathway to\nexperimentally probe phonon transport mechanisms with unprecedented details."
    },
    {
        "anchor": "Exploring N-rich phases in LixNy clusters for hydrogen storage at\n  nano-scale: We have performed cascade genetic algorithm and ab initio atomistic\nthermodynamics under the framework of first-principles density functional\ntheory to study the (meta-)stability of a wide range of LixNy clusters. We\nfound that hybrid xc-functional is essential to address this problem as a\nlocal/semi-local functional simply fails even to predict a qualitative\nprediction. Most importantly, we find that though in bulk Lithium Nitride, Li\nrich phase, i.e. Li3N, is the stable stoichiometry, in small LixNy clusters\nN-rich phases are more stable at thermodynamic equilibrium. We further show a\nthat these N-rich clusters are promising hydrogen storage material because of\ntheir easy adsorption and desorption ability at respectively low (< 300K) and\nmoderately high temperature (> 600K).",
        "positive": "Lattice effects on the formation of oxygen vacancies in perovskite thin\n  films: We use first-principles methods to investigate the effects of collective\nlattice excitations on the formation of oxygen vacancies in perovskite thin\nfilms. We find that phonons play a crucial role on the strain-mediated control\nof defect chemistry at finite temperatures. In particular, zero-temperature\noxygen vacancy formation trends deduced as a function of epitaxial strain can\nbe fully reversed near room temperature. Our first-principles calculations\nevidence a direct link between the lattice contribution to the oxygen vacancy\nfree energy and the volume expansion that the system undergoes when is\nchemically reduced: The larger the resulting volume expansion, the more\nfavorable thermal excitations are to point defect formation. However, the\ninterplay between the vibrational vacancy entropy, or equivalently, chemical\nexpansion, and epitaxial strain is difficult to generalise as this can be\nstrongly influenced by underlying structural and magnetic transitions. In\naddition, we find that vacancy ordering can be largely hindered by the thermal\nlattice excitations."
    },
    {
        "anchor": "Robust atmospherically stable hybrid SrVO3/Graphene//SrTiO3 template for\n  fast and facile large-area transfer of complex oxides onto Si: Heterogenous integration of complex epitaxial oxides onto Si and other target\nsubstrates is recently gaining traction. One of the popular methods involves\ngrowing a water-soluble and highly reactive sacrificial buffer layer, such as\nSr3Al2O6 (SAO) at the interface, and a functional oxide on top of this. To\nimprove the versatility of layer transfer techniques, it is desired to utilize\nstable (less reactive) sacrificial layers, without compromising on the transfer\nrates. In this study, we utilized a combination of chemical vapor deposited\n(CVD) graphene as a 2D material at the interface and pulsed laser deposited\n(PLD) water-soluble SrVO3 (SVO) as a sacrificial buffer layer. We show that the\ngraphene layer enhances the dissolution rate of SVO over ten times without\ncompromising its atmospheric stability. We demonstrate the versatility of our\nhybrid template by growing ferroelectric BaTiO3 (BTO) via PLD and Pb(Zr, Ti)O3\n(PZT) via Chemical Solution Deposition (CSD) technique and transferring them\nonto the target substrates and establishing their ferroelectric properties. Our\nhybrid templates allow for the realization of the potential of complex oxides\nin a plethora of device applications for MEMS, electro-optics, and flexible\nelectronics.",
        "positive": "Adsorption of organic molecules at the TiO2(110) surface: the effect of\n  van der Waals interactions: Understanding the interaction of organic molecules with TiO2 surfaces is\nimportant for a wide range of technological applications. While density\nfunctional theory (DFT) calculations can provide valuable insight about these\ninteractions, traditional DFT approaches with local exchange-correlation\nfunctionals suffer from a poor description of non-bonding van der Waals (vdW)\ninteractions. We examine here the contribution of vdW forces to the interaction\nof small organic molecules (methane, methanol, formic acid and glycine) with\nthe TiO2 (110) surface, based on DFT calculations with the optB88-vdW\nfunctional. The adsorption geometries and energies at different configurations\nwere also obtained in the standard generalized gradient approximation (GGA-PBE)\nfor comparison. We find that the optB88-vdW consistently gives shorter surface\nadsorbate-to-surface distances and slightly stronger interactions than PBE for\nthe weak (physisorbed) modes of adsorption. In the case of strongly adsorbed\n(chemisorbed) molecules both functionals give similar results for the\nadsorption geometries, and also similar values of the relative energies between\ndifferent chemisorption modes for each molecule. In particular both functionals\npredict that dissociative adsorption is more favourable than molecular\nadsorption for methanol, formic acid and glycine, in general agreement with\nexperiment. The dissociation energies obtained from both functionals are also\nvery similar, indicating that vdW interactions do not affect the thermodynamics\nof surface deprotonation. However, the optB88-vdW always predicts stronger\nadsorption than PBE. The comparison of the methanol adsorption energies with\nvalues obtained from a Redhead analysis of temperature programmed desorption\ndata suggests that optB88-vdW significantly overestimates the adsorption\nstrength, although we warn about the uncertainties involved in such\ncomparisons."
    },
    {
        "anchor": "Evolution of the neutron quasi-elastic scattering through the\n  ferroelectric phase transition in 93%PbZn$_{1/3}$Nb$_{2/3}$O$_3$ - 7%\n  PbTiO$_3$: We show that the neutron diffuse scattering in relaxor ferroelectric\n(1-x)PbZn$_{1/3}$Nb$_{2/3}$O$_{3}$ - x PbTiO$_{3}$ (x=0.07) consists of two\ncomponents. The first component is strictly elastic but extended in q-space and\ngrows below 600 K. The second component, that was not reported before for the\n(1-x)PbZn$_{1/3}$Nb$_{2/3}$O$_{3}$ - x PbTiO$_{3}$ (x=0.07) relaxor\nferroelectrics, is quasi-elastic with a line-width that has a similar\ntemperature dependence as the width of the central peak observed by Brillouin\nspectroscopy. The temperature dependence of the susceptibility of the\nquasi-elastic scattering has a maximum at the ferroelectric transition.",
        "positive": "Comparison of near-interface traps in Al$_2$O$_3$/4H-SiC and\n  Al$_2$O$_3$/SiO$_2$/4H-SiC structures: Aluminum oxide (Al2O3) has been grown by atomic layer deposition on n-type\n4H-SiC with and without a thin silicon dioxide (SiO2) intermediate layer. By\nmeans of Capacitance Voltage and Thermal Dielectric Relaxation Current\nmeasurements, the interface properties have been investigated. Whereas for the\nsamples with an interfacial SiO2 layer the highest near-interface trap density\nis found at 0.3 eV below the conduction band edge, Ec, the samples with only\nthe Al2O3 dielectric exhibit a nearly trap free region close to Ec. For the\nAl2O3/SiC interface, the highest trap density appears between 0.4 to 0.6 eV\nbelow Ec. The results indicate the possibility for SiC-based MOSFETs with Al2O3\nas the gate dielectric layer in future high performance devices."
    },
    {
        "anchor": "Photoemission Signatures of Non-Equilibrium Carrier Dynamics from First\n  Principles: Time- and angle-resolved photoemission spectroscopy (tr-ARPES) constitutes a\npowerful tool to inspect the dynamics and thermalization of hot carriers. The\nidentification of the processes that drive the dynamics, however, is\nchallenging even for the simplest systems owing to the coexistence of several\nrelaxation mechanisms. Here, we devise a Green's function formalism for\npredicting the tr-ARPES spectral function and establish the origin of carrier\nthermalization entirely from first principles. The predictive power of this\napproach is demonstrated by an excellent agreement with experiments for\ngraphene over time scales ranging from a few tens of femtoseconds up to several\npicoseconds. Our work provides compelling evidence of a non-equilibrium\ndynamics dominated by the establishment of a hot-phonon regime.",
        "positive": "Formation of Zn and Pb sulfides in a redox-sensitive modern system due\n  to high atmospheric fallout: The study shows that the air-derived metal enrichment (up to 2.3 g Zn kg-1,\n1.1 g Pb kg-1, and 62 mg Cd kg-1) is retained in a thin layer (~30 cm) around\n10-15 cm below the peat surface. A combination of focused ion beam (FIB)\ntechnology and scanning (SEM) and transmission (TEM) electron microscopy\nreveals that micrometric spheroids are most characteristic for ZnS and\n(Zn,Cd)S, although the sulfides readily form pseudomorphs after different plant\ntissues resulting in much larger aggregates. The aggregates have a complex\npolycrystalline sphalerite structure much more advanced than typically obtained\nduring low-temperature synthesis or observed in other modern occurrences. Platy\nhighly-disordered radially-aggregated submicrometre crystals develop within the\ntime constraints of several decades in the cold (~15{\\deg}C) and acid (pH\n3.4-4.4) peat. The less abundant Pb sulfides occur as submicron cube-like\ncrystals between ZnS or as flat irregular or square patches on plant root\nmacrofossils. All PbS are crystalline and defect-free. Pb ion complexation with\ndissolved and solid organic matter is probably responsible for the low number\nand equilibrium shape of PbS crystals. Iron is absent in the authigenic sulfide\nmineralization and occurs entirely as organically bound ferric iron (Fe3+), as\nrevealed by Mossbauer spectroscopy. The different affinity of metals to organic\nmatter enhances the precipitation of Zn and Cd as sulfides over Pb and Fe. Our\nfindings demonstrate that human activities lead to the formation of\nnear-surface stratiform metal sulfide accumulations in peat, and the polluted\nsites can be of use to understand and reconstruct ancient ore deposits' genesis\nand mechanisms of formation."
    },
    {
        "anchor": "Adsorption of Benzene on the RuO2(110) Surface: Hydrocarbon tribopolymer, a type of polymer formed due to friction between\nsurfaces, is a major impediment to the development of micro- and\nnanoelectromechanical systems (MEMS/NEMS) devices for industrial application.\nTribopolymer buildup can prevent MEMS and NEMS from making or breaking\nelectrical contact. We describe the adsorption of benzene (C6H6) on the\nRuO2(110) surface using density functional theory. This adsorption is an\nimportant initial step in the mechanism of hydrocarbon tribopolymer layer\nformation on MEMS and NEMS devices. The adsorption interaction is studied by\nconsidering three oxygen coverages of RuO2(110) and all the possible adsorption\nsites for benzene. We find that adsorption of benzene on O-poor RuO2(110) via\nC-Ru bonds is stronger than adsorption on the O-rich RuO2(110) via H-O bonds.\nFor an in-depth study of the adsorption behavior, we include the van der Waals\ninteraction for a holistic investigation. By incorporating the thermodynamic\nchemical potentials into the adsorption simulations, we describe a model that\ncan provide guidance for realistic situations.",
        "positive": "Effect of slip transmission at grain boundaries in Al bicrystals: The effect of slip transfer on the deformation mechanisms of Al bicrystals\nwas explored using a rate-dependent dislocation-based crystal plasticity model.\nThree different types of grain boundaries (GBs) were included in the model by\nmodifying the rate of dislocation accumulation near the GB in the Kocks-Mecking\nlaw, leading to fully-opaque (dislocation blocking), fully-transparent and\npartially-transparent GBs. In the latter, slip transmission is only allowed in\npairs of SS in neighbour grains that are suitably oriented for slip transfer\naccording to the Luster-Morris parameter. Modifications of the GB character led\nto important changes in the deformation mechanisms at the GB. In general,\nbicrystals with fully-opaque boundaries showed an increase in the dislocation\ndensity near the GB, which was associated with an increase in the Von Mises\nstress. In contrast, the dislocation pile-ups and the stress concentration were\nless pronounced in the case of partially-transparent boundaries as the slip in\none grain can progress into the next grain with some degree of continuity. No\nstress concentrations were found at these boundaries for fully-transparent\nboundaries, and there was continuity of strain across the boundary, which is\nnot typical of most experimentally observed GBs. Simulations of ideal\nbicrystals oriented for favorable slip transfer on the most highly favored slip\nsystem in grains with high Schmid factors for slip transfer depends on the\nnumber of active SS in operation in the neighborhood and that most boundaries\nwill lead to nearly opaque conditions while some boundaries will be\ntransparent. Finally, the model was applied to a particular experimentally\nobserved GB in which slip transfer was clearly operating indicating that the\nmodel predicted a nearly transparent GB."
    },
    {
        "anchor": "Ultralow Thermal Conductivity in Full-Heusler Semiconductors: Semiconducting half- and, to a lesser extent, full-Heusler compounds are\npromising thermoelectric materials due to their compelling electronic\nproperties with large power factors. However, intrinsically high thermal\nconductivity resulting in a limited thermoelectric efficiency has so far\nimpeded their widespread use in practical applications. Here, we report the\ncomputational discovery of a class of hitherto unknown stable semiconducting\nfull-Heusler compounds with ten valence electrons ($X_2YZ$, $X$=Ca, Sr, and Ba;\n$Y$= Au and Hg; $Z$=Sn, Pb, As, Sb, and Bi) through high-throughput $ab-initio$\nscreening. These new compounds exhibit ultralow lattice thermal conductivity\n$\\kappa_{\\text{L}}$ close to the theoretical minimum due to strong anharmonic\nrattling of the heavy noble metals, while preserving high power factors, thus\nresulting in excellent phonon-glass electron-crystal materials.",
        "positive": "Polaron Transport in Organic Crystals: Temperature Tuning of Disorder\n  Effects: We explore polaronic quantum transport in three-dimensional models of\ndisordered organic crystals with strong coupling between electronic and\nvibrational degrees of freedom. By studying the polaron dynamics in a static\ndisorder environment, temperature dependent mobilities are extracted and found\nto exhibit different fingerprints depending on the strength of the disorder\npotential. At low temperatures and for strong enough disorder, coherence\neffects induce weak localization of polarons. These effects are reduced with\nincreasing temperature (thermal disorder) resulting in mobility increase.\nHowever at a transition temperature, phonon-assisted contributions driven by\npolaron-phonon scattering prevail, provoking a downturn of the mobility. The\nresults provide an alternative scenario to discuss controversial experimental\nfeatures in molecular crystals."
    },
    {
        "anchor": "Quantification of uncertainty in first-principles predicted mechanical\n  properties of solids: Application to solid ion conductors: Computationally-guided material discovery is being increasingly employed\nusing a descriptor-based screening through the calculation of a few properties\nof interest. A precise understanding of the uncertainty associated with first\nprinciples density functional theory calculated property values is important\nfor the success of descriptor-based screening. Bayesian error estimation\napproach has been built-in to several recently developed exchange-correlation\nfunctionals, which allows an estimate of the uncertainty associated with\nproperties related to the ground state energy, for e.g. adsorption energies.\nHere, we propose a robust and computationally efficient method for quantifying\nuncertainty in mechanical properties, which depends on the derivatives of the\nenergy. The procedure involves calculating the energy around the equilibrium\ncell volume with different strains and fitting the obtained energies to the\ncorresponding energy-strain relationship. At each strain, we use instead of a\nsingle energy, an ensemble of energies, giving us an ensemble of fits and\nthereby, an ensemble of mechanical properties associated with each fit, whose\nspread can be used to quantify its uncertainty. The generation of ensemble of\nenergies is only a post-processing step involving a perturbation of parameters\nof the exchange-correlation functional and solving for the energy non-self\nconsistently. The proposed method is computationally efficient and provides a\nmore robust uncertainty estimate compared to the approach of self-consistent\ncalculations employing several different exchange-correlation functionals. We\ndemonstrate the method by calculating the uncertainty bounds for Si using the\ndeveloped method. We show that the calculated uncertainty bounds the property\nvalues obtained using three different GGA functionals: PBE, PBEsol and RPBE.",
        "positive": "Structural and optical properties of micro-diamonds with SiV- color\n  centers: Isolated, micro-meter sized diamonds are grown by micro-wave plasma chemical\nvapour deposition technique on Si(001) substrates. Each diamond is uniquely\nidentified by markers milled in the Si substrate by Ga+ focused ion beam. The\nmorphology and micrograin structure analysis indicates that the diamonds are\nicosahedral or bi-crystals. Icosahedral diamonds have higher (up to\n$\\sigma_\\mathrm{h}$ = 2.3 GPa), and wider distribution\n($\\Delta\\sigma_\\mathrm{h}$ = 4.47 GPa) of hydrostatic stress built up at the\nmicrocrystal grain boundaries, compared to the other crystals. The number and\nspectral shape of SiV- color centers incorporated in the micro-diamonds is\nanalysed, and estimated by means of temperature dependent photoluminescence\nmeasurements, and Montecarlo simulations. The Montecarlo simulations indicate\nthat the number of SiV- color centers is a few thousand per micro-diamond."
    },
    {
        "anchor": "Coupling a reactive potential with a harmonic approximation for\n  atomistic simulations of material failure: Molecular dynamics (MD) simulations involving reactive potentials can be used\nto model material failure. The empirical potentials which are used in such\nsimulations are able to adapt to the atomic environment, at the expense of a\nsignificantly higher computational cost than non-reactive potentials. However,\nduring a simulation of failure, the reactive ability is needed only in some\nlimited parts of the system, where bonds break or form and the atomic\nenvironment changes. Therefore, simpler non-reactive potentials can be used in\nthe remainder of the system, provided that such potentials reproduce correctly\nthe behavior of the reactive potentials in this region, and that seamless\ncoupling is ensured at the interface between the reactive and non-reactive\nregions. In this article, we propose a methodology to combine a reactive\npotential with a non-reactive approximation thereof, made of a set of harmonic\npair and angle interactions and whose parameters are adjusted to predict the\nsame energy, geometry and Hessian in the ground state of the potential. We\npresent a methodology to construct the non-reactive approximation of the\nreactive potential, and a way to couple these two potentials. We also propose a\ncriterion for on-the-fly substitution of the reactive potential by its\nnon-reactive approximation during a simulation. We illustrate the correctness\nof this hybrid technique for the case of MD simulation of failure in\ntwo-dimensional graphene originally modeled with REBO potential.",
        "positive": "Acoustic Metal: Metal reflects electromagnetic waves because of the large conductivity that\nis responsible for dissipation. During which the waves undergo a 180$^\\circ$\nphase change that is independent of the frequency. There is no counterpart\nmaterial for acoustic waves. Here we show that by using an array of acoustic\nresonators with a designed high-density dissipative component, an \"acoustic\nmetal\" can be realised that strongly couples with sound over a wide frequency\nrange not otherwise attainable by conventional means. In particular, we show\nthe acoustic Faraday cage effect that when used as a ring covering an air duct,\n99% of the noise can be blocked without impeding the airflow. We further\ndelineate the underlying volume requirement for an acoustic metal based on the\nconstraint of the causality principle. Our findings complement the missing\nproperties of acoustic materials and pave the way to the strong wave-material\ncouplings that are critical for the applications as high-performance audio\ndevices."
    },
    {
        "anchor": "Transition from Ferromagnetism to Antiferromagnetism in\n  Ga$_{1-x}$Mn$_x$N: Using density functional theory, we study the magnetic stability of the\nGa$_{1-x}$Mn$_x$N alloy system. We show that unlike Ga$_{1-x}$Mn$_x$As, which\nshows only ferromagnetic (FM) phase, Ga$_{1-x}$Mn$_x$N can be stable in either\nFM or antiferromagnetic phases depending on the alloy concentration. The\nmagnetic order can also be altered by applying pressure or with charge\ncompensation. A unified model is used to explain these behaviors.",
        "positive": "Intersubband Electronic Properties of InAs/GaAs Quantum Dot Molecules\n  with Horizontal Spacer: In this work the intersubband electronic properties of two laterally coupled\ndome-shaped InAs/GaAs quantum dots were investigated. The envelope functions\nand eigenenergies were calculated as function of distance between the dots. The\ncoupling between the dots was studied using transition lifetime between the\ndots. The results showed that in close distances (smaller than 3 nm) the\nquantum dots are coupled and by increasing the distance transition lifetime\nfall down drastically and the dots become uncoupled."
    },
    {
        "anchor": "Homogenous and heterogeneous magnetism in (Zn,Co)O: A series of (ZnO)m(CoO)n digital alloys and superlattices grown by atomic\nlayer deposition has been investigated by a range of experimental methods. The\ndata provide evidences that the Co interdiffusion in the digital alloy\nstructures is sufficient to produce truly random Zn1-xCoxO mixed crystals with\nx up to 40%. Conversely, in the superlattice structures the interdiffusion is\nnot strong enough to homogenize the Co content along the growth direction\nresults in the formation of (Zn,Co)O films with spatially modulated Co\nconcentrations. All structures deposited at 160\\circC show magnetic properties\nspecific to dilute magnetic semiconductors with localized spins S = 3/2 coupled\nby strong but short range antiferromagnetic interactions that lead to low\ntemperature spin-glass freezing.\n  It is demonstrated that ferromagnetic-like features, visible exclusively in\nlayers grown at 200\\circC and above, are associated with an interfacial mesh of\nmetallic Co granules residing between the substrate and the (Zn,Co)O layer.\nThis explains why the magnitude of ferromagnetic signal is virtually\nindependent of the film thickness as well as elucidates the origin of magnetic\nanisotropy. Our conclusions have been derived for layers in which the Co\nconcentration, distribution, and aggregation have been determined by:\nsecondary-ion mass spectroscopy, electron probe micro-analysis, high-resolution\ntransmission electron microscopy with capabilities allowing for chemical\nanalysis; x-ray absorption near-edge structure; extended x-ray absorption\nfine-structure; x-ray photoemission spectroscopy, and x-ray circular magnetic\ndichroism. Macroscopic properties of these layers have been investigated by\nsuperconducting quantum interference device magnetometery and microwave\ndielectric losses allowing to confirm the important role of metallic\ninclusions.",
        "positive": "The Enhanced Ferromagnetism of Single-Layer CrX3 (X=Br and I) by Van der\n  Waals Engineering: The recent experimental discovery of intrinsic ferromagnetism in single-layer\nCrI3 opens a new avenue to low-dimensional spintronics. However, the low Curie\ntemperature Tc=45 K is still a large obstacle to its realistic device\napplication. In this work, we demonstrate that the Tc and magnetic moment of\nCrX3(X=Br, I) can be enhanced simultaneously by coupling them to buckled\ntwo-dimensional Mene (M=Si, Ge) to form magnetic van der Waals (vdW)\nheterostructures. Our first-principles calculations reveal that n-doping of\nCrX3, induced by a significant spin-dependent interlayer charge transfer from\nMene, is responsible for its drastic enhancement of Tc and magnetic moment.\nFurthermore, the diversified electronic properties including halfmetallicity\nand semi-conductivity with configuration dependent energy gap are also\npredicted in this novel vdW heterostructure, implying their broad potential\napplications in spintronics. Our study suggests that the vdW engineering may be\nan efficient way to tune the magnetic properties of 2D magnets, and the\nMene_CrX3 magnetic vdW heterostructures are wonderful candidates in spintronics\nand nanoelectronics device."
    },
    {
        "anchor": "Calorimetric and magnetic study for Ni$_{50}$Mn$_{36}$In$_{14}$ and\n  relative cooling power in paramagnetic inverse magnetocaloric systems: The non-stoichiometric Heusler alloy Ni$_{50}$Mn$_{36}$In$_{14}$ undergoes a\nmartensitic phase transformation in the vicinity of 345 K, with the high\ntemperature austenite phase exhibiting paramagnetic rather than ferromagnetic\nbehavior, as shown in similar alloys with lower-temperature transformations.\nSuitably prepared samples are shown to exhibit a sharp transformation, a\nrelatively small thermal hysteresis, and a large field-induced entropy change.\nWe analyzed the magnetocaloric behavior both through magnetization and direct\nfield-dependent calorimetry measurements. For measurements passing through the\nfirst-order transformation, an improved method for heat-pulse relaxation\ncalorimetry was designed. The results provide a firm basis for the analytic\nevaluation of field-induced entropy changes in related materials. An analysis\nof the relative cooling power (RCP), based on the integrated field-induced\nentropy change and magnetizing behavior of the Mn spin system with\nferromagnetic correlations, shows that a significant RCP may be obtained in\nthese materials by tuning the magnetic and structural transformation\ntemperatures through minor compositional changes or local order changes.",
        "positive": "Colossal dielectric constant up to GHz at room temperature: The search for new materials with extremely high (\"colossal\") dielectric\nconstants, required for future electronics, is one of the most active fields of\nmodern materials science. However, the applicability of the colossal-epsilon'\nmaterials, discovered so far, suffers from the fact that their dielectric\nconstant, epsilon', only is huge in a limited frequency range below about 1\nMHz. In the present report, we show that the dielectric properties of\nLa15/8Sr1/8NiO4 surpass those of other materials. Especially, epsilon' retains\nits colossal magnitude of >10000 well into the GHz range. This material is\nprone to charge order and this spontaneous ordering process of the electronic\nsubsystem can be assumed to play an important role in the generation of the\nobserved unusual dielectric properties."
    },
    {
        "anchor": "Ferromagnetism at 300 K in spin-coated anatasea and rutile\n  Ti0.95Fe0.05O2 films: Thin films of Ti1-xFexO2 (x=0 and 0.05) have been prepared on sapphire\nsubstrates by spin-on technique starting from metal organic precursors. When\nheat treated in air at 550 and 700 degrees C respectively, these films present\npure anatase and rutile structures as shown both by X-ray diffraction and Raman\nspectroscopy. Optical absorption indicate a high degree of transparency in the\nvisible region. Such films show a very small magnetic moment at 300 K. However,\nwhen the anatase and the rutile films are annealed in a vacuum of 1x10-5 Torr\nat 500 degrees C and 600 degrees C respectively, the magnetic moment, at 300 K,\nis strongly enhanced reaching 0.46 $\\mu$B/Fe for the anatase sample and 0.48\n$\\mu$B/Fe for the rutile one. The ferromagnetic Curie temperature of these\nsamples is above 350 K.",
        "positive": "Polar Surface Effects on the Thermal Conductivity in ZnO Nanowires: a\n  Shell-Like Surface Reconstruction-Induced Preserving Mechanism: We perform molecular dynamics (MD) simulations to investigate the effect of\npolar surfaces on the thermal transport in zinc oxide (ZnO) nanowires. We find\nthat the thermal conductivity in nanowires with free polar (0001) surfaces is\nmuch higher than in nanowires that have been stabilized with reduced charges on\nthe polar (0001) surfaces, and also hexagonal nanowires without any transverse\npolar surfaces. From normal mode analysis, we show that the higher thermal\nconductivity is due to a shell-like reconstruction that occurs for the free\npolar surfaces. This shell-like reconstruction suppresses twisting motion in\nthe nanowires such that the bending phonon modes are not scattered by the other\nphonon modes, and leads to substantially higher thermal conductivity in the ZnO\nnanowire with free polar surfaces. Furthermore, the auto-correlation function\nof the normal mode coordinate is utilized to extract the phonon lifetime, which\nleads to a concise explanation for the higher thermal conductivity in ZnO\nnanowires with free polar surfaces. Our work demonstrates that ZnO nanowires\nwithout polar surfaces, which exhibit low thermal conductivity, are more\npromising candidates for thermoelectric applications than nanowires with polar\nsurfaces (and also high thermal conductivity)."
    },
    {
        "anchor": "Low-cycle fatigue of a nickel-based superalloy at high temperature:\n  Simplified micromechanical modelling: This work is focused on the micromechanical modelling of the low cycle\nfatigue of the nickel based $\\gamma/\\gamma'$ superalloy AM1 at high\ntemperature. The nature of the activated slip systems in the different types of\nchannels of the $\\gamma$ phase is analysed, taking into account the combined\neffects of the applied and internal stresses. The latter are split into two\ncontributions, misfit stresses and compatibility stresses between the elastic\n$\\gamma'$ phase and the elasto-plastic $\\gamma$ phase, which are estimated\nwithin a simplified composite approach. Internal stresses may induce slip\nactivity and/or be relaxed by it, which results in a complex sequence of slip\nactivation events in the different channels under increasing applied stress.\nThe consideration of these effects leads to a prediction of the nature and\ndistribution of the active slip systems within the channels in [001] tension,\ncompression and during low cycle fatigue. The resulting microstructural\nbehaviour and its consequences regarding the anisotropic nature of the\ncoalescence of the $\\gamma'$ precipitates are discussed with respect to the\navailable experimental data.",
        "positive": "Instabilities of switching processes in synthetic antiferromagnets: It is shown that magnetic states and field-driven reorientation transitions\nin synthetic antiferromagnets crucially depend on contributions of higher-order\nanisotropies. A phenomenological macrospin model is derived to describe the\nmagnetic states of two antiferromagnetically coupled magnetic thin film\nelements. The calculated phase diagrams show that magnetic states with\nout-of-plane magnetization, symmetric escaped spin-flop phases, exist in a\nbroad range of the applied magnetic field. Due to the formation of such states\nand concomitant multidomain patterns, the switching processes in toggle\nmagnetic random access memory devices (MRAM) can radically deviate from\npredictions within oversimplified models."
    },
    {
        "anchor": "Superior surface modification layer of poly(styrene) on SiO$_2$ gate\n  insulator in rubrene single crystal field-effect transistor: We conduct comparative research on the density of states of electron- and\nhole- carrier trap levels (DTR(E)), dispersing inside the energy gap of a\nrubrene single crystal in a field effect transistor (FET) struction with Ca and\nAu hetero-electrodes for an ambipolar carrier injection mode, by using\npolymeric protection-layer materials on a Si substrate. Three different types\nof polymeric materials, poly(methyl-methacrylate) (PMMA), poly(styrene) (PS)\nand poly(chloro-styrene) (PCS) are employed. From the temperature (T)-dependent\nsource-drain current and gate voltage (ISD-VG) transfer characteristics, the\nvalues of DTR(E) are evaluated. PS exhibits the most efficiently-balanced\nambipolar carrier transport, which is superior to PMMA that is most typically\nused as the standard protection layer on a SiO$_2$/doped-Si substrate.\nDiscussions are made in the framework of a carrier multiple trap and release\n(CMTR) model.",
        "positive": "Lattice dynamics of the high temperature shape memory alloy Nb-Ru: Nb-Ru is a high temperature shape memory alloy that undergoes a Martensitic\ntransformation from a parent cubic b-phase into a tetragonal b' phase at TM 900\nC. Measurements of the phonon dispersion curves show that the [110]-TA2 phonon\nbranch, corresponding in the q=0 limit to the elastic constant C'=1/2(C11-C12)\nhas an anomalous temperature dependence. Nearly the entire branch softens with\ndecreasing temperature as TM is approached. The temperature dependence of the\nlow-q phonon energies suggests that the elastic constants would approach 0 as T\napproaches TM, indicating a second order transition. No additional lattice\nmodulation is observed in the cubic phase."
    },
    {
        "anchor": "Theory of finite strain superplasticity: The plastic flow of a polycrystal is analyzed assuming grains as fine that\nthe rate limiting process is grain boundary sliding, and grains readily\naccommodate their shapes by slip to preserve spatial continuity. It is shown\nthat thinking of a polycrystal with randomly oriented grains as an homogeneous\nand isotropic continuum when dealing with it as a dynamical medium, even in a\nscale much larger than the grain size, leads to gross errors. The polyhedral\nnature of grains influences the plastic flow in a radical manner, as the\nrelative velocity of adjacent grains is constrained to the common boundary\nplane, and only the in--plane shear stress contributes to their relative\nmotion. This constriction determines that the divergency of the velocity field\nof the material medium does not vanish, and plastic deformation necessarily\ninvolves grain volume variations, which can only be elastic. As this has a\nlimit, fracture follows as a necessary step of plastic flow. A theoretical\napproach to plastic flow is developed, and emphasis is done in superplastic\ndeformation, from zero to fracture strain. The theory allows to quantitatively\nexplain the observed features of superplastic materials and responds to many\nopen questions in the field.",
        "positive": "Stabilization of tetragonal/cubic phase in Fe doped Zirconia grown by\n  atomic layer deposition: Achieving high temperature ferromagnetism by doping transition metals thin\nfilms is seen as a viable approach to integrate spin-based elements in\ninnovative spintronic devices. In this work we investigated the effect of Fe\ndoping on structural properties of ZrO2 grown by atomic layer deposition (ALD)\nusing Zr(TMHD)4 for Zr and Fe(TMHD)3 for Fe precursors and ozone as oxygen\nsource. The temperature during the growth process was fixed at 350{\\deg}C. The\nALD process was tuned to obtain Fe doped ZrO2 films with uniform chemical\ncomposition, as seen by time of flight secondary ion mass spectrometry. The\ncontrol of Fe content was effectively reached, by controlling the ALD precursor\npulse ratio, as checked by X-ray photoemission spectroscopy (XPS) and\nspectroscopic ellipsometry. From XPS, Fe was found in Fe3+ chemical state,\nwhich maximizes the magnetization per atom. We also found, by grazing incidence\nX-ray diffraction, that the inclusion of Fe impurities in ZrO2 induces\namorphization in thin ZrO2 films, while stabilizes the high temperature\ncrystalline tetragonal/cubic phase after rapid thermal annealing at 600{\\deg}C."
    },
    {
        "anchor": "Universal self-assembly of one-component three-dimensional dodecagonal\n  quasicrystals: Using molecular dynamics simulations, we study computational self-assembly of\none-component three-dimensional dodecagonal (12-fold) quasicrystals in systems\nwith two-length-scale potentials. Existing criteria for three-dimensional\nquasicrystal formation are quite complicated and rather inconvenient for\nparticle simulations. So to localize numerically the quasicrystal phase, one\nshould usually simulate over a wide range of system parameters. We show how to\nuniversally localize the parameters values at which dodecagonal quasicrystal\norder may appear for a given particle system. For that purpose, we use a\ncriterion recently proposed for predicting decagonal quasicrystal formation in\none-component two-length-scale systems. The criterion is based on two\ndimensionless effective parameters describing the fluid structure which are\nextracted from radial distribution function. The proposed method allows\nreducing the time spent for searching the parameters favoring certain solid\nstructure for a given system. We show that the method works well for\ndodecagonal quasicrystals; this results is verified on four systems with\ndifferent potentials: Dzugutov potential, oscillating potential which mimics\nmetal interactions, repulsive shoulder potential describing effective\ninteraction for core/shell model of colloids and embedded-atom model potential\nfor aluminum. Our results suggest that mechanism of dodecagonal quasicrystal\nformation is universal for both metallic and soft-matter systems and it is\nbased on competition between interparticle scales.",
        "positive": "Bias-controlled sensitivity of ferromagnet/semiconductor electrical spin\n  detectors: Using Fe/GaAs Schottky tunnel barriers as electrical spin detectors, we show\nthat the magnitude and sign of their spin-detection sensitivities can be widely\ntuned with the voltage bias applied across the Fe/GaAs interface. Experiments\nand theory establish that this tunability derives not just simply from the bias\ndependence of the tunneling conductances $G_{\\uparrow,\\downarrow}$ (a property\nof the interface), but also from the bias dependence of electric fields in the\nsemiconductor which can dramatically enhance or suppress spin-detection\nsensitivities. Electrons in GaAs with fixed polarization can therefore be made\nto induce either positive or negative voltage changes at spin detectors, and\nsome detector sensitivities can be enhanced over ten-fold compared to the usual\ncase of zero-bias spin detection."
    },
    {
        "anchor": "Imaging Ferroelectric Domains via Charge Gradient Microscopy Enhanced by\n  Principal Component Analysis: Local domain structures of ferroelectrics have been studied extensively using\nvarious modes of scanning probes at the nanoscale, including piezoresponse\nforce microscopy (PFM) and Kelvin probe force microscopy (KPFM), though none of\nthese techniques measure the polarization directly, and the fast formation\nkinetics of domains and screening charges cannot be captured by these\nquasi-static measurements. In this study, we used charge gradient microscopy\n(CGM) to image ferroelectric domains of lithium niobate based on current\nmeasured during fast scanning, and applied principal component analysis (PCA)\nto enhance the signal-to-noise ratio of noisy raw data. We found that the CGM\nsignal increases linearly with the scan speed while decreases with the\ntemperature under power-law, consistent with proposed imaging mechanisms of\nscraping and refilling of surface charges within domains, and polarization\nchange across domain wall. We then, based on CGM mappings, estimated the\nspontaneous polarization and the density of surface charges with order of\nmagnitude agreement with literature data. The study demonstrates that PCA is a\npowerful method in imaging analysis of scanning probe microscopy (SPM), with\nwhich quantitative analysis of noisy raw data becomes possible.",
        "positive": "Quantified Uncertainty in Thermodynamic Modeling for Materials Design: Phase fractions, compositions and energies of the stable phases as a function\nof macroscopic composition, temperature, and pressure (X-T-P) are the principle\ncorrelations needed for the design of new materials and improvement of existing\nmaterials. They are the outcomes of thermodynamic modeling based on the\nCALculation of PHAse Diagrams (CALPHAD) approach. The accuracy of CALPHAD\npredictions vary widely in X-T-P space due to experimental error, model\ninadequacy and unequal data coverage. In response, researchers have developed\nframeworks to quantify the uncertainty of thermodynamic property model\nparameters and propagate it to phase diagram predictions. In previous studies,\nuncertainty was represented as intervals on phase boundaries (with respect to\ncomposition) or invariant reactions (with respect to temperature) and was\nunable to represent the uncertainty in eutectoid reactions or in the stability\nof phase regions. In this work, we propose a suite of tools that leverages\nsamples from the multivariate model parameter distribution to represent\nuncertainty in forms that surpass previous limitations and are well suited to\nmaterials design. These representations include the distribution of phase\ndiagrams and their features, as well as the dependence of phase stability and\nthe distributions of phase fraction, composition activity and Gibbs energy on\nX-T-P location - irrespective of the total number of components. Most\ncritically, the new methodology allows the material designer to interrogate a\ncertain composition and temperature domain and get in return the probability of\ndifferent phases to be stable, which can positively impact materials design."
    },
    {
        "anchor": "Field-asymmetric transverse magnetoresistance in a nonmagnetic\n  quantum-size structure: A new phenomenon is observed experimentally in a heavily doped asymmetric\nquantum-size structure in a magnetic field parallel to the quantum-well layers\n- a transverse magnetoresistance which is asymmetric in the field (there can\neven be a change in sign) and is observed in the case that the structure has a\nbuilt-in lateral electric field. A model of the effect is proposed. The\nobserved asymmetry of the magnetoresistance is attributed to an additional\ncurrent contribution that arises under nonequilibrium conditions and that is\nlinear in the gradient of the electrochemical potential and proportional to the\nparameter characterizing the asymmetry of the spectrum with respect to the\nquasimomentum.",
        "positive": "Competition between Ferrimagnetism and Magnetic Frustration in Zinc\n  Substituted YBaFe4O7: The substitution of zinc for iron in YBaFe4O7 has allowed the oxide series\nYBaFe4-xZnxO7, with 0.40 < x < 1.50, belonging to the \"114\" structural family\nto be synthesized. These oxides crystallize in the hexagonal symmetry (P63mc),\nas opposed to the cubic symmetry (F-43m) of YBaFe4O7. Importantly, the d.c.\nmagnetization shows that the zinc substitution induces ferrimagnetism, in\ncontrast to the spin glass behaviour of YBaFe4O7. Moreover, a.c. susceptibility\nmeasurements demonstrate that concomitantly these oxides exhibit a spin glass\nor a cluster glass behaviour, which increases at the expense of ferrimagnetism,\nas the zinc content is increased. This competition between ferrimagnetism and\nmagnetic frustration is interpreted in terms of lifting of the geometric\nfrustration, inducing the magnetic ordering, and of cationic disordering, which\nfavours the glassy state."
    },
    {
        "anchor": "On the sulfur doping of gamma-graphdiyne: A Molecular Dynamics and DFT\n  study: Recently, an experimental study developed an efficient way to obtain\nsulfur-doped gamma-graphdiyne. This study has shown that this new material\ncould have promising applications in lithium-ion batteries, but the complete\nunderstanding of how the sulfur atoms are incorporated into the graphdiyne\nnetwork is still missing. In this work, we have investigated the sulfur doping\nprocess through molecular dynamics and density functional theory simulations.\nOur results suggest that the doped induced distortions of the gamma-graphdiyne\npores prevent the incorporation of more than two sulfur atoms. The most common\nconfiguration is the incorporation of just one sulfur atom per the graphdiyne\npore.",
        "positive": "The interface between Sr$_2$RuO$_4$ and Ru-metal inclusion--Implications\n  for its superconductivity: Under various conditions of the growth process, when the presumably\nunconventional superconductor Sr$_2$RuO$_4$ (SRO) contains micro-inclusions of\nRu metal, the superconducting critical temperature increases significantly. An\nSTEM study shows a sharp interface geometry which allows crystals of SRO and of\nRu-metal to grow side by side by forming a commensurate superlattice structure\nat the interface. In an attempt to shed light as to why this happens, we\ninvestigated the atomic structure and electronic properties of the interface\nbetween the oxide and the metal micro-inclusions using density functional\ntheory (DFT) calculations. Our results support the observed structure\nindicating that it is energetically favored over other types of Ru-metal/SRO\ninterfaces. We find that a $t_{2g}$-$e_g$ orbital mixing occurs at the\ninterface with significantly enhanced magnetic moments. Based on our findings,\nwe argue that an inclusion mediated interlayer coupling reduces phase\nfluctuations of the superconducting order parameter which could explain the\nobserved enhancement of the superconducting critical temperature in SRO samples\ncontaining micro-inclusions."
    },
    {
        "anchor": "Application of multivariate Tromp functions for evaluating the joint\n  impact of particle size, shape and wettability on the separation of ultrafine\n  particles via flotation: Froth flotation predominantly separates particles according to their\ndifferences in wettability. However, other particle properties such as size,\nshape or density significantly influence the separation outcome as well. Froth\nflotation is most efficient for particles within a size range of about\n$20-200\\mu m$, but challenges arise for very fine or coarse particles that are\naccompanied by low recoveries and poor selectivity. While the impact of\nparticle size on the separation behavior in flotation is well-known by now, the\neffect of particle shape is less studied and varies based on the investigated\nzone (suspension or froth) and the separation apparatus used. A\nmultidimensional perspective on the separation process, considering multiple\nparticle properties, enhances the understanding of their collective influence.\nIn this paper the two-dimensional case is studied, i.e., a parametric modeling\napproach is applied to determine bivariate Tromp functions from scanning\nelectron microscopy-based image data of the feed and the separated fractions.\nWith these functions it is possible to characterize the separation behavior of\nparticle systems. Using a model system of ultrafine ($<10\\mu m$) particles,\nconsisting of differently shaped glass particles with different wettability\nstates as the floatable and magnetite as the non-floatable fraction, allows for\ninvestigating the influence of particle size, shape and wettability, on the\nseparation. In this way, the present paper contributes to a better\nunderstanding of the complex interplay between certain property vectors for the\ncase of ultrafine particles. Furthermore, it demonstrates the benefits of using\nmultivariate Tromp functions for evaluating separation processes, and points\nout the limitations of SEM based image measurements by means of mineral\nliberation analysis (MLA) for the studied particle size fraction.",
        "positive": "Extension of Ashby's performance indexes in mixed tension-bending\n  solicitation: Ashby's performance indexes are a fundamental tool for material selection\nespecially for structures lightening. Unfortunately the indexes are available\nonly for simple mechanical solicitation as pure bending or pure tension. For\nreal applications, it is required to have a performance index for combined\nsolicitations. This publication proposes an approach to develop this kind of\nextended performance index and shows the exploitation in order to compare\nmaterials performance in more realistic situations."
    },
    {
        "anchor": "Effects of dopant type and concentration on the femtosecond laser\n  ablation threshold and incubation behaviour of silicon: In laser micromachining, the ablation threshold (minimum fluence required to\ncause ablation) is a key performance parameter and overall indicator of the\nefficiency of material removal. For pulsed laser micromachining, this important\nobservable depends upon material properties, pulse properties and the number of\npulses applied in a complex manner that is not yet well understood. The\nincubation effect is one example. It manifests as a change in the ablation\nthreshold as a function of number of laser pulses applied and is driven by\nphotoinduced defect accumulation in the material. Here, we study femtosecond\n(800 nm, 110 fs, 0.1-1 mJ/pulse) micromachining of a material with well-defined\ninitial defect concentrations: doped Si across a range of dopant types and\nconcentrations. The single-pulse ablation threshold (Fth,1) was observed to\ndecrease with increasing dopant concentration, from a maximum of 0.70 J/cm2\n(+/-0.02) for undoped Si to 0.51 J/cm2 (+/-0.01) for highly N-type doped Si.\nThe effect was greater for N-type doped Si than for P-type, consistent with the\nhigher carrier mobility of electrons compared to holes. In contrast, the\ninfinite-pulse ablation threshold (Fth,inf) was the same for all doping levels\nand types. We attribute this asymptotic behaviour to a maximum defect\nconcentration that is independent of the initial defect concentration and type.\nThese results lend insight into the mechanism of multipulse, femtosecond laser\nablation.",
        "positive": "Multiphase tin equation of state using density functional theory: We perform density functional theory (DFT) calculations of five solid phases\nand the liquid phase of tin. The calculations include cold curves of the five\nsolid phases, phonon calculations in the quasi-harmonic approximation over a\nrange of volumes for each solid phase, and DFT-based molecular dynamics\n(DFT-MD) calculations of the liquid phase. Using the DFT results, we construct\na tabular multiphase SESAME equation of state for tin, referred to as SESAME\n2162. Comparisons to experimental data are made and show a high level of\nagreement in isobaric data, isothermal data, shock data, and phase boundary\nmeasurements, including measurements of the melt curve. The 2162 EOS will be\nuseful for hydrodynamics simulations and has been designed with an eye toward\nhydrodynamics simulations that incorporate materials strength models and allow\nfor modeling of the kinetics of phase transitions."
    },
    {
        "anchor": "PMN: a minimal induced-moment soft pseudo-spin glass perspective: An argument that relaxor ferroelectricity in the isovalent alloy $\\mathrm\n{Ba(Zr}_{1-x}\\mathrm{Ti}_{x})\\mathrm{O}_3$ can be understood as an induced\nmoment soft pseudo-spin glass on the B-ions of the $\\mathrm{ABO}_{3}$ matrix is\nextended to the experimentally paradigmic but theoretically more complex\nheterovalent relaxor $\\mathrm {Pb(Mg}_{1/3}\\mathrm{Nb}_{2/3}\\mathrm{)O}_3$\n(PMN). It is argued that interesting behaviour of the onset of non-ergodicity,\nfrequency-dependent susceptibility peaks and precursor nanodomains can be\nunderstood from analagous considerations of the B-ions, with the displacements\nof the Pb ions a largely independent, but distracting, side-feature. This\ncontrasts with conventional conceptualizations.",
        "positive": "Controlling the energy of defects and interfaces in the amplitude\n  expansion of the phase-field crystal model: One of the major difficulties in employing phase field crystal (PFC) modeling\nand the associated amplitude (APFC) formulation is the ability to tune model\nparameters to match experimental quantities. In this work we address the\nproblem of tuning the defect core and interface energies in the APFC\nformulation. We show that the addition of a single term to the free energy\nfunctional can be used to increase the solid-liquid interface and defect\nenergies in a well-controlled fashion, without any major change to other\nfeatures. The influence of the newly added term is explored in two-dimensional\ntriangular and honeycomb structures as well as bcc and fcc lattices in three\ndimensions. In addition, a finite element method (FEM) is developed for the\nmodel that incorporates a mesh refinement scheme. The combination of the FEM\nand mesh refinement to simulate amplitude expansion with a new energy term\nprovides a method of controlling microscopic features such as defect and\ninterface energies while simultaneously delivering a coarse-grained examination\nof the system."
    },
    {
        "anchor": "Octahedral distortions in SrNbO$_3$: Unraveling the structure-property\n  relation: Strontium niobate has triggered a lot of interest as a transparent conductor\nand as a possible realization of a correlated Dirac semi-metal. Using the\nlattice parameters as a tunable knob, the energy landscape of octahedral\ntilting was mapped using density functional theory calculations. We find that\nbiaxial compressive strain induces tilting around the out-of-plane axis, while\ntensile strain induces tilting around the two in-plane axes. The two competing\ndistorted structures for compressive strain show semi-Dirac dispersions above\nthe Fermi level in their electronic structure. Our density functional theory\ncalculations combined with dynamical mean field theory (DFT+DMFT) reveals that\ndynamical correlations downshift these semi-Dirac like cones towards the Fermi\nenergy. More generally, our study reveals that the competition between the\nin-phase and out-of-phase tilting in SrNbO$_3$ provides a new degree of freedom\nwhich allows for tuning the thermoelectric and optical properties. We show how\nthe tilt angle and mode is reflected in the behavior of the Seebeck coefficient\nand the plasma frequency, due to changes in the band structure.",
        "positive": "A Short Working Distance Multiple Crystal X-ray Spectrometer: For x-ray spot sizes of a few tens of microns or smaller, a mm-sized flat\nanalyzer crystal placed ~ 1 cm from the sample will exhibit high energy\nresolution while subtending a collection solid angle comparable to that of a\ntypical spherically bent crystal analyzer (SBCA) at much larger working\ndistances. Based on this observation and a non-focusing geometry for the\nanalyzer optic, we have constructed and tested a short working distance (SWD)\nmulticrystal x-ray spectrometer. This prototype instrument has a maximum\neffective collection solid angle of 0.14 sr, comparable to that of 17 SBCA at 1\nmeter working distance. We find good agreement with prior work for measurements\nof the Mn K_beta x-ray emission and resonant inelastic x-ray scattering (RIXS)\nfor MnO and also for measurements of the x-ray absorption near-edge structure\nfor Dy metal using Lalpha2 partial-fluorescence yield detection. We discuss\nfuture applications at third- and fourth-generation light sources. For\nconcentrated samples, the extremely large collection angle of SWD spectrometers\nwill permit collection of high-resolution x-ray emission spectra with a single\npulse of the Linac Coherent Light Source."
    },
    {
        "anchor": "Microscopic description of insulator-metal transition in high-pressure\n  oxygen: Unusual metallic states involving breakdown of the standard Fermi-liquid\npicture of long-lived quasiparticles in well-defined band states emerge at low\ntemperatures near correlation-driven Mott transitions. Prominent examples are\nill-understood metallic states in $d$- and $f$-band compounds near Mott-like\ntransitions. Finding of superconductivity in solid O$_{2}$ on the border of an\ninsulator-metal transition at high pressures close to 96~GPa is thus truly\nremarkable. Neither the insulator-metal transition nor superconductivity are\nunderstood satisfactorily. Here, we undertake a first step in this direction by\nfocussing on the pressure-driven insulator-metal transition using a combination\nof first-principles density-functional and many-body calculations. We report a\nstriking result: the finding of an orbital-selective Mott transition in a pure\n$p$-band elemental system. We apply our theory to understand extant structural\nand transport data across the transition, and make a specific two-fluid\nprediction that is open to future test. Based thereupon, we propose a novel\nscenario where soft multiband modes built from microscopically coexisting\nitinerant and localized electronic states are natural candidates for the\npairing glue in pressurized O$_{2}$.",
        "positive": "Non-equilibrium BN-ZnO: Optical properties and excitonic effects from\n  first principles: The non-equilibrium boron nitride (BN) phase of zinc oxide (ZnO) has been\nreported for thin films and nanostructures, however, its properties are not\nwell understood due to a persistent controversy that prevents reconciling\nexperimental and first-principles results for its atomic coordinates. We use\nfirst-principles theoretical spectroscopy to accurately compute electronic and\noptical properties, including single-quasiparticle and excitonic effects: Band\nstructures and densities of states are computed using density functional\ntheory, hybrid functionals, and the $GW$ approximation. Accurate optical\nabsorption spectra and exciton binding energies are computed by solving the\nBethe-Salpeter equation for the optical polarization function. Using this data\nwe show that the band-gap difference between BN-ZnO and wurtzite (WZ) ZnO\nagrees very well with experiment when the theoretical lattice geometry is used,\nbut significantly disagrees for the experimental atomic coordinates. We also\nshow that the optical anisotropy of BN-ZnO differs significantly from that of\nWZ-ZnO, allowing to optically distinguish both polymorphs. By using the\ntransfer-matrix method to solve Maxwell's equations for thin films composed of\nboth polymorphs, we illustrate that this opens up a promising route for tuning\noptical properties."
    },
    {
        "anchor": "Slow electronic rearrangement kinetic involving O- after shot quenching\n  from >600K of YBa2Cu3Oy: Analysis of kinetic literature suggests several electronic rearrangements\nabove 600K involving O- (subperoxides) in YBa2Cu3Oy. Slow cooling to 260K\nproduces a Tc=50K level with conventional plane and cell volume contracted\nvarieties (P-V-), based on plane oxidizing (4) where (n) denotes local O\ncoordination. When these materials are quenched from <600K, the subsequent\nchanges at 298K of structural parameters or Tc have activation energies E=92kJ\nand A=1.0x10-12s. The changes saturate at temperatures where they are faster\nthan the time constant t of quenching. This temperature is extended to 473K\nwith SQ, indicating t=0.1s. SQ of y near 6.44 from >600K leads to increased\naxial ratios, plane and V expansion (P+V+), in a process which is complete near\n670 and extending to 950K. P+V+ effects can far exceed P0V0 of the respective\nsemiconductor. The relative stability at elevated temperatures indicates\nanother intrinsically slower transformation mechanism of primarily electronic\nnature with E=280kJ, involving O-. V+ and its Tc=100K level, is ascribed to (3)\nwith doped charge on apical O-, acting as a plane expander and n-doper. Similar\nslowing of kinetic through O- also hold for the more complex range of Tq>950K.\nIt can produce a c-axis contracted non-superconductor (P+C-) and indications\nfor elevated temperature superconductivity (ETS) with Tc>150K*. Kinetic data\nare embedded into general thermodynamic arguments concerning peroxide stability\nbelts.",
        "positive": "Heteroepitaxial integration of ZnGeN2 on GaN buffers using molecular\n  beam epitaxy: Recently theorized hybrid II-IV-N{_2} / III-N heterostructures, based on\ncurrent commercialized (In,Ga)N devices, are predicted to significantly advance\nthe design space of highly efficient optoelectronics in the visible spectrum,\nyet there are few epitaxial studies of II-IV-N{_2} materials. In this work, we\npresent heteroepitaxial ZnGeN{_2} grown on GaN buffers and AlN templates. We\ndemonstrate that a GaN nucleating surface is crucial for increasing the\nZnGeN{_2} crystallization rate to combat Zn desorption, extending the\nstoichiometric growth window from 215 {\\degree}C on AlN to 500 {\\degree}C on\nGaN buffers. Structural characterization reveals well crystallized films with\nthreading dislocations extending from the GaN buffer. These films have a\ncritical thickness for relaxation of 20 nm - 25 nm as determined by reflection\nhigh energy electron diffraction (RHEED) and cross-sectional scanning electron\nmicroscopy (SEM). The films exhibit a cation-disordered wurtzite structure,\nwith lattice constants a = 3.216 {\\AA} {\\pm} 0.004 {\\AA} and c = 5.215 {\\AA}\n{\\pm} 0.005 {\\AA} determined by RHEED and X-ray diffraction (XRD). This work\ndemonstrates a significant step towards the development of hybrid ZnGeN{_2}-GaN\nintegrated devices."
    },
    {
        "anchor": "A novel experimental method of estimating tracer and intrinsic diffusion\n  coefficients from multicomponent diffusion profiles: A few decades earlier, Kirkaldy and Lane proposed an indirect method of\nestimating the tracer and intrinsic diffusion coefficients in a ternary system\n(without showing experimental verification), which is otherwise impossible\nfollowing the Kirkendall marker experiments. Subsequently, Manning proposed the\nrelations between the tracer and intrinsic diffusion coefficients in the\nmulticomponent system by extending the Onsager formalism (although could not be\nestimated by intersecting the diffusion couples). By solving these issues in\nthis article, we have now proposed the equations and method for estimating\nthese parameters in pseudo-ternary diffusion couples in which diffusion paths\ncan be intersected in multicomponent space. We have chosen NiCoFeCr system for\nverification of this method because of the availability of good quality\ndiffusion couple experiments and estimated tracer diffusion coefficients of all\nthe components measured by the radiotracer method. An excellent match is found\nwhen the tracer diffusion coefficients estimated following the newly proposed\nmethod are compared with the data estimated following the radiotracer method.\nFollowing, the intrinsic diffusion coefficients are estimated experimentally in\na multicomponent system for the first time highlighting diffusional\ninteractions between the components. We have further shown that the intrinsic\ndiffusion coefficients are the same (if the vacancy wind effect is\nnegligible/neglected) when estimated from other types of diffusion couples\n(pseudo-binary and body diagonal) in the same multi-component system. This\nmethod can be now extended to the Al, Ga, Si containing systems in which the\nestimation of tracer diffusion coefficients following the radiotracer method is\ndifficult/impossible because of various reasons.",
        "positive": "Crystal Growth of Cu6(Ge,Si)6O18.6H2O and Assignment of UV-VIS Spectra\n  in Comparison to Dehydrated Dioptase and Selected Cu(II) Oxo-Compounds\n  Including Cuprates: It is reported on growth of mm-sized single-crystals of the low-dimensional S\n= 1/2 spin compound Cu6(Ge,Si)6O18.6H2O by a diffusion technique in aqueous\nsolution. A route to form Si-rich crystals down to possibly dioptase, the pure\nsilicate, is discussed. Further, the assignment of dd excitations from UV-VIS\nspectra of the hexahydrate and the fully dehydrated compound is proposed in\ncomparison to dioptase and selected Cu(II) oxo-compounds using bond strength\nconsiderations. Non-doped cuprates as layer compounds show higher excitation\nenergies than the title compound. However, when the antiferromagnetic\ninteraction energy as Jzln(2) is taken into account for cuprates, a single\nlinear relationship between the Dqe excitation energy and equatorial Cu(II)-O\nbond strength is confirmed for all compounds. A linear representation is also\nconfirmed between 2A1g energies and a function of axial and equatorial Cu-O\nbond distances, when auxiliary axial bonds are used for four-coordinated\ncompounds. The quotient Dt/Ds of experimental orbital energies deviating from\nthe general trend to smaller values indicates the existence of H2O respectively\nCl1- axial ligands in comparison to oxo-ligands, whereas larger Dt/Dqe values\nindicate missing axial bonds. The quotient of the excitation energy 2A1g by\n2x2Eg-2B2g allows to check for correctness of the assignment and to distinguish\nbetween axial oxo-ligands and others like H2O or Cl1-. Some assignments\npreviously reported were corrected."
    },
    {
        "anchor": "Ferroelectric Transition in Compressively Strained SrTiO3 Thin Films: We report the temperature dependent capacitance-voltage characteristics of\nPt/SrTiO3 Schottky diodes fabricated using compressively strained SrTiO3 thin\nfilms grown on (LaAlO3)0.3(Sr2AlTaO6)0.7 (LSAT) substrates. The measurements\nreveal a divergence of the out of plane dielectric constant of SrTiO3 peaked at\n~140K, implying a ferroelectric transition. A Curie-Weiss law fit to the\nzero-bias dielectric constant suggests a Curie temperature of ~56 K. This\nobservation provides experimental confirmation of the theoretical prediction of\nout of plane ferroelectricity in compressively strained SrTiO3 thin films grown\non LSAT substrate. We also discuss the roles of the field-dependent dielectric\nconstant and the interfacial layer in SrTiO3 on the extraction of the Curie\ntemperature.",
        "positive": "Giant magnetic quantum oscillations in the thermal conductivity of TaAs:\n  Indications of chiral zero sound: Charge transport of topological semimetals has been in the focus of intensive\ninvestigations because of their non-trivial band topology. Heat transport of\nthese materials, on the other hand, is largely unexplored and remains elusive.\nHere we report on an observation of unprecedented, giant magnetic quantum\noscillations of thermal conductivity in the prototypical Weyl semimetal TaAs.\nThe oscillations are antiphase with the quantum oscillating electronic density\nof states of a Weyl pocket, and their amplitudes amount to two orders of\nmagnitude of the estimation based on the Wiedemann-Franz law. Our analyses show\nthat all the conventional heat-transport mechanisms through diffusions of\npropagating electrons, phonons and electron-hole bipolar excitations, are far\ninadequate to account for these phenomena. Taking further experimental facts\nthat the parallel field configuration favors much higher magneto-thermal\nconductivity, we propose that the newly proposed chiral zero sound provides a\nreasonable explanation to these exotic phenomena. More work focusing on other\ntopological semimetals along the same line is badly called for."
    },
    {
        "anchor": "Atomistic simulations of ductile failure in a b.c.c. high entropy alloy: Ductile failure is studied in a bcc HfNbTaZr High Entropy Alloy (HEA) with a\npre-existing void. Using molecular dynamics simulations of uniaxial tensile\ntests, we explore the effect of void radius on the elastic modulus and yield\nstress. The elastic modulus scales with porosity as in closed-cell foams. The\ncritical stress for dislocation nucleation as a function of the void radius is\nvery well described by a model designed after pure bcc metals, taking into\naccount a larger core radius for the HEA. Twinning takes place as a\ncomplementary deformation mechanism, and some detwinning occurs at large\nstrain. No solid-solid phase transitions are identified. The concurrent effects\nof element size mismatch and plasticity lead to significant lattice disorder.\nBy comparing our HEA results to pure tantalum simulations, we show that the\ncritical stress for dislocation nucleation and the resulting dislocation\ndensities are much lower than for pure Ta, as expected from lower energy\nbarriers due to chemical complexity",
        "positive": "Two-Dimensional h-BN and MoS2 as Diffusion Barriers for Ultra-Scaled\n  Copper Interconnects: Copper interconnects in modern integrated circuits require ultra-thin\nbarriers to prevent intermixing of Cu with surrounding dielectric materials.\nConventional barriers rely on metals like TaN, however their finite thickness\nreduces the cross-sectional area and significantly increases the resistivity of\nnanoscale interconnects. In this study, a new class of two-dimensional (2D) Cu\ndiffusion barriers, hexagonal boron nitride (h-BN) and molybdenum disulfide\n(MoS2), is demonstrated for the first time. Using time-dependent dielectric\nbreakdown measurements and scanning transmission electron microscopy coupled\nwith energy dispersive X-ray spectroscopy and electron energy loss\nspectroscopy, these 2D materials are shown to be promising barrier solutions\nfor ultra-scaled interconnect technology. The predicted lifetime of devices\nwith directly deposited 2D barriers can achieve three orders of magnitude\nimprovement compared to control devices without barriers."
    },
    {
        "anchor": "Spontaneous and mass-conserved formation of continuous Si frameworks: Controlled formation of porous silicon has been of primary importance for\nnumerous landmark applications such as light emitting sources, sensors,\nactuators, drug delivery systems, and energy storage applications. Frequently\nexplored methods to form the structures have long relied on selective etching\nof silicon, which still stands as the most controllable and reliable methods to\nhighlight essence of the applications. Here, we demonstrate an unprecedented\napproach to form silicon framework, which is spontaneously formed with\natomistic arrangement of silicon without gravimetric loss via single\nelectrochemical (de)alloying with lithium. Carefully controlling bare\ncrystallinity of Si and composite/electrode designs, we reveal that the key\nprerequisite to forming the structure lies in using unique dealloying dynamics\nof crystalline-amorphous phase transformations at room temperature. Using the\nfeature, we clearly highlight that commercially available nano-structured\nsilicon particles can abruptly yet uniformly transform into continuous sub-2 nm\nspherical silicon frameworks with size-tunable pores.",
        "positive": "The AFLOW Library of Crystallographic Prototypes: Part 4: The AFLOW Library of Crystallographic Prototypes has been updated to include\nan additional 683 entries, which now reaches 1,783 prototypes. We have also\nmade some changes to the presentation of the entries, including a more\nconsistent definition of the AFLOW-prototype label and a better explanation of\nour choice of space group when the experimental data is ambiguous. A method is\npresented for users to submit new prototypes for the Encyclopedia. We also\ninclude a complete index linking to all the prototypes currently in the\nLibrary."
    },
    {
        "anchor": "Ab-initio calculation of the electronic and optical excitations in\n  polythiophene: effects of intra- and interchain screening: We present an calculation of the electronic and optical excitations of an\nisolated polythiophene chain as well as of bulk polythiophene. We use the GW\napproximation for the electronic self-energy and include excitonic effects by\nsolving the electron-hole Bethe-Salpeter equation. The inclusion of interchain\nscreening in the case of bulk polythiophene drastically reduces both the\nquasi-particle band gap and the exciton binding energies, but the optical gap\nis hardly affected. This finding is relevant for conjugated polymers in\ngeneral.",
        "positive": "First-principles studies of multiferroic and magnetoelectric materials: Multiferroics are materials where two or more ferroic orders coexist owing to\nthe interplay between spin, charge, lattice and orbital degrees of freedom. The\nexplosive expansion of multiferroics literature in recent years demon-strates\nthe fast growing interest in this field. In these studies, the first-principles\ncalculation has played a pioneer role in the experiment explanation, mechanism\ndiscovery and prediction of novel multiferroics or magnetoelectric materials.\nIn this review, we discuss, by no means comprehensively, the extensive\napplications and successful achievements of first-principles approach in the\nstudy of multiferroicity, magnetoelectric effect and tunnel junc-tions. In\nparticular, we introduce some our recently developed methods, e.g., the orbital\nselective external potential (OSEP) method, which prove to be powerful tools in\nthe finding of mechanisms responsible for the intriguing phe-nomena occurred in\nmultiferroics or magnetoelectric materials. We also summarize first-principles\nstudies on three types of electric control of magnetism, which is the common\ngoal of both spintronics and multiferroics. Our review offers in depth\nunderstanding on the origin of ferroelectricity in transition metal oxides, and\nthe coexistence of fer-roelectricity and ordered magnetism, and might be\nhelpful to explore novel multiferroic or magnetoelectric materi-als in the\nfuture."
    },
    {
        "anchor": "Metallic Hydrogen: Experiments on Metastability: Molecular hydrogen was pressurized in a diamond anvil cell at temperatures\nbetween 5 and 83 K. At a sufficiently high pressure, estimated to be between\n477 to 491 GPa, hydrogen became metallic, determined by its reflectance in the\nnear infrared and fit to a Drude free-electron model. We then studied the\npredicted metastability of metallic hydrogen. At a temperature of 5 K the load\non the metallic hydrogen was stepwise reduced until the pressure was zero.\nWhile turning the load or pressure down, the sample evidently transformed to\nthe molecular phase and escaped; the sample hole closed. We estimate this\npressure to be 113 to 84 GPa. Metallic hydrogen was not observed to be\nmetastable at zero pressure.",
        "positive": "Mechanisms of temperature-dependent thermal transport in amorphous\n  silica from machine-learning molecular dynamics: Amorphous silica (a-SiO$_2$) is a foundational disordered material for which\nthe thermal transport properties are important for various applications. To\naccurately model the interatomic interactions in classical molecular dynamics\n(MD) simulations of thermal transport in a-SiO$_2$, we herein develop an\naccurate yet highly efficient machine-learned potential model that allowed us\nto generate a-SiO$_2$ samples closely resembling experimentally produced ones.\nUsing the homogeneous nonequilibrium MD method and a proper quantum-statistical\ncorrection to the classical MD results, quantitative agreement with experiments\nis achieved for the thermal conductivities of bulk and 190 nm-thick a-SiO$_2$\nfilms over a wide range of temperatures. To interrogate the thermal vibrations\nat different temperatures, we calculated the current correlation functions\ncorresponding to the transverse acoustic (TA) and longitudinal acoustic (LA)\ncollective vibrations. The results reveal that below the Ioffe-Regel crossover\nfrequency, phonons as well-defined excitations, remain applicable in a-SiO$_2$\nand play a predominant role at low temperatures, resulting in a\ntemperature-dependent increase in thermal conductivity. In the high-temperature\nregion, more phonons are excited, accompanied by a more intense liquid-like\ndiffusion event. We attribute the temperature-independent thermal conductivity\nin the high-temperature range of a-SiO$_2$ to the collaborative involvement of\nexcited phonon scattering and liquid-like diffusion in heat conduction. These\nfindings provide physical insights into the thermal transport of a-SiO$_2$ and\nare expected to be applied to a vast range of amorphous materials."
    },
    {
        "anchor": "Anomalous stopping and charge transfer in proton-irradiated graphene: We use first-principles calculations to uncover and explain a new type of\nanomalous low-velocity stopping effect in proton-irradiated graphene. We\nattribute a shoulder feature that occurs exclusively for channeling protons to\nenhanced electron capture from $\\sigma$+$\\pi$ orbitals. Our analysis of\nelectron emission indicates that backward emission is more sensitive to proton\ntrajectory than forward emission and could thus produce higher contrast images\nin ion microscopy. For slow protons, we observe a steep drop in emission,\nconsistent with predictions from analytical models.",
        "positive": "Boundary integral formulation for cracks at imperfect interfaces: We consider an infinite bi-material plane containing a semi-infinite crack\nsituated on a soft imperfect interface. The crack is loaded by a general\nasymmetrical system of forces distributed along the crack faces. On the basis\nof the weight function approach and the fundamental reciprocal identity, we\nderive the corresponding boundary integral formulation, relating physical\nquantities. The boundary integral equations derived in this paper in the\nimperfect interface setting show a weak singularity, in contrast to the perfect\ninterface case, where the kernel is of the Cauchy type. We further present\nthree alternative variants of the boundary integral equations which offer\ncomputationally favourable alternatives for certain sets of parameters."
    },
    {
        "anchor": "Understanding first order Raman spectra of boron carbides across the\n  homogeneity range: Boron carbide, a lightweight, high temperature material, has various\napplications as a structural material and as a neutron absorber. The large\nsolubility range of carbon in boron, between $\\approx$ 9% and 20%, stems from\nthe thermodynamical stability of three icosahedral phases at low temperature,\nwith respective carbon atomic concentrations: 8.7% (B$_{10.5}$C, named\nOPO$_1$), 13.0 \\% (B$_{6.7}$C, named OPO$_2$), whose theoretical Raman spectra\nare still unknown, and 20% (B$_4$C), from which the nature of some of the Raman\npeaks are still debated. We report theoretical and experimental results of the\nfirst order, non-resonant, Raman spectrum of boron carbide. Density functional\nperturbation theory enables us to obtain the Raman spectra of the OPO$_1$ and\nOPO$_2$ phases, which are perfectly ordered structures with a complex\ncrystalline motif of 414 atoms, due to charge compensation effects. Moreover,\nfor the carbon-rich B$_4$C, with a simpler 15-atom unit cell, we study the\ninfluence of the low energy point defects and of their concentrations on the\nRaman spectrum, in connection with experiments, thus providing insights into\nthe sensitivity of experime ntal spectra to sample preparation, experimental\nconditions and setup. In particular, this enables us to propose a new structure\nat 19.2% atomic carbon concentration, B$_{4.2}$C, that lies very close to the\nconvex hull of boron carbide, on the carbon-rich side. This new phase, derived\nfrom what we name the \"3+1\" defect complex, helps in reconciling the\nexperimentally observed Raman spectrum with the theory around 1000 cm$^{-1}$.\nFinally, we predict the intensity variations induced by the experimental\ngeometry and quantitavely assess the localisation of bulk and defect\nvibrational modes and their character, with an analysis of \"chain\" and\n\"icosahedral\" modes.",
        "positive": "First Principles Study of Photocatalytic Water Splitting by\n  M$_1$M$_2$CO$_2$ (M$_1$ = Zr,Hf; M$_2$ = Hf,Ti,Sc) MXenes: Using density functional theory (DFT), we investigated the structural,\nelectronic and optical properties of functionalized and doped MXenes such as\nM$_1$M$_2$CO$_2$ (M$_1$ = Zr,Hf; M$_2$ = Hf,Ti,Sc). This study aimed to find a\nsuitable photocatalyst that would work well in the water splitting process.\nAmong the calculated nanostructures, MXenes ZrHfCO$_2$ and ZrTiCO$_2$ were\nchosen as the suitable photocatalysts for the water splitting process. The\ncalculated value of the band gaps with the GGA-PBE functional was 1.08(0.79) eV\nfor the ZrHfCO$_2$ (ZrTiCO$_2$) monolayer. Also, the band gaps for these\nmonolayers with the HSE06 hybrid functional were 1.86 and 1.57 eV,\nrespectively. These MXenes' optical properties, such as complex dielectric\nfunction, refractive index, extinction coefficient, and reflectivity, were also\ninvestigated. The results showed that these monolayers had good absorption in\nthe visible and ultraviolet regions. Additionally, we discovered that\nZrHfCO$_2$ and ZrTiCO$_2$ MXenes could be used for the water splitting process\nby calculating the photocatalytic properties. Meanwhile, the results showed\nthat the monolayers of M$_1$M$_2$CO$_2$ could be promising candidates for\nphotocatalytic, solar energy, and optoelectronic applications."
    },
    {
        "anchor": "Effect of the flash annealing on the impurity distribution and the\n  electronic structure in the inversion layer: Hole subband structure under strong band bending such a Pb on Si(111) and\nIndium on Si(111) have been investigated by angle-resolved photoelectron\nspectroscopy(ARPES). Energy levels of hole subband structure which indicate the\nquantized levels in inversion layer are strongly depend on band bend shape\nwhich can be controlled by the impurity concentration of substrate. Meanwhile,\nthe discrepancy for the suband energy separation between experimental results\nand calculation results is also observed. In this study, we aim to clarify the\nrelationship between flash annealing and impurity concentration and the hole\nsubband. From this results, it was found out that high temperature flash\nannealing at 1250 degree has considerable effect on the impurity concentration\nat subsurface region by Secondary Ion Mass spectroscopy (SIMS) and our\ndiffusion model. This effect makes the band bend shape and subband energy\nseparation change. Moreover, It was revealed that the reduction of the impurity\ndistribution was inhibited less than 900 degree of the flashing temperature.",
        "positive": "Hydrogenation of graphene in view of odd electrons correlation: The paper presents evidence of a rather strong correlation of odd electrons\nin the singlet state of graphene. Due to the correlation, the chemical\nmodification of graphene can be considered following a certain algorithmic\ncomputational procedure. Originated due to the correlation and distributed over\nthe carbon atoms of graphene membrane with fraction numbers NDA, effectively\nunpaired electrons lay the algorithm foundation. The highest NDA value points\nto the target atom that enters a chemical reaction at the considered step.\nFollowing the pointers, a stepwise design of polyderivatives can be performed.\nApplied to the hydrogenation, the algorithmic design has exhibited that\ngraphene hydrogenation should be attributed to a highly complicated event,\nwhose final hydride products depend on a number of factors such as: 1) the\nmanner of the graphene membrane fixation; 2) the accessibility of the membrane\nboth sides to hydrogen; 3) the composition (molecular or atomic) of the\nhydrogen. In general, the hydride formation is multimode in regards composition\nand structure. Thus, the formation of 100% hydride with regular chairlike\nhexagonal packing of CH units which can be attributed to graphane is possible\nif only the graphene membrane is fixed over perimeter while its basal plane is\naccessible to hydrogen atoms from both sides."
    },
    {
        "anchor": "Xenon NMR Measurements of Permeability and Tortuosity in Reservoir Rocks: In this work we present measurements of permeability, effective porosity and\ntortuosity on a variety of rock samples using NMR/MRI of thermal and\nlaser-polarized gas. Permeability and effective porosity are measured\nsimultaneously using MRI to monitor the inflow of laser-polarized xenon into\nthe rock core. Tortuosity is determined from measurements of the time-dependent\ndiffusion coefficient using thermal xenon in sealed samples. The initial\nresults from a limited number of rocks indicate inverse correlations between\ntortuosity and both effective porosity and permeability. Further studies to\nwiden the number of types of rocks studied may eventually aid in explaining the\npoorly understood connection between permeability and tortuosity of rock cores.",
        "positive": "$K$ dependent exchange interaction of the $1S$ ortho exciton in Cu$_2$O: When treating the exchange interaction of Wannier excitons, usually only the\nleading terms of the analytic and the nonanalytic exchange interaction are\nconsidered. However, higher order terms can lead to a splitting of exciton\nstates, for which reason a splitting of the $1S$~exciton in cuprous oxide\n$\\left(\\mathrm{Cu_{2}O}\\right)$ depending on its total momentum $\\hbar K$ has\nbeen attributed to a $K$ dependent analytic exchange interaction by Dasbach et\nal [Phys. Rev. Lett. 91, 107401 (2003)]. Going beyond the common treatment of\nthe exchange interaction, we derive the correct expressions for these $K$\ndependent higher order terms using $\\boldsymbol{k}\\cdot\\boldsymbol{p}$\nperturbation theory. We prove that the appearance of a $K$ dependent exchange\ninteraction is inseparably connected with a $K$ independent exchange\ninteraction of $P$ and $D$ excitons. We estimate the magnitude of these terms\nfor $\\mathrm{Cu_{2}O}$ from microscopic calculations and show that they are far\ntoo small to explain the observed $K$ dependent splitting. Instead, this\nsplitting has to be treated in terms of the dispersion of the excitons.\nFurthermore, we prove the occurence of a coupling between longitudinal and\ntransverse excitons in $\\mathrm{Cu_{2}O}$ due to the $K$ dependent nonanalytic\nexchange interaction."
    },
    {
        "anchor": "Equation of State of Uranium and Plutonium: The objective of this work is to define the parameters of the three-term\nequation of state for uranium and plutonium, appropriate for conditions in\nwhich these materials are subjected to strong shock compressions, as in\ncylindrical and spherical implosions.\n  The three-term equation of state takes into account the three components of\nthe pressure that resist to compression in the solid: the elastic or \"cold\"\npressure (coulombian repulsion between atoms), the thermal pressure due to\nvibratory motion of atoms in the lattice of the solid and the thermal pressure\nof electrons thermally excited. The equation of state defined here permits also\nto take into account the variation of the specific heat with the transition of\nthe solid to the liquid or gaseous state due to continued growth of temperature\nin strong shock compressions.\n  In the definition of uranium equation of state, experimental data on the\nuranium compression, available in the open scientific literature, are used. In\nthe plutonium case, this element was considered initially in the alpha-phase or\nstabilized in the delta-phase. In the last case, an abrupt and instantaneous\ntransition to the alpha-phase was considered when the delta-phase plutonium is\nsubmitted to strong compressions.",
        "positive": "MBE-grown 232-270 nm Deep-UV LEDs using Monolayer thin Binary GaN/AlN\n  quantum heterostructures: Electrically injected deep ultra-violet (UV) emission is obtained using\nmonolayer (ML) thin GaN/AlN quantum structures as active regions. The emission\nwavelength is tuned by controlling the thickness of ultrathin GaN layers with\nmonolayer precision using plasma assisted molecular beam epitaxy (PAMBE).\nSingle peaked emission spectra is achieved with narrow full width at half\nmaximum (FWHM) for three different light emitting diodes (LEDs) operating at\n232 nm, 246 nm and 270 nm. 232 nm (5.34 eV) is the shortest EL emission\nwavelength reported so far using GaN as the light emitting material and\nemploying polarization-induced doping."
    },
    {
        "anchor": "Multiple Dirac Cones and Topological Magnetism in Honeycomb-Monolayer\n  Transition Metal Trichalcogenides: The discovery of monolayer graphene has initiated two fertile fields in\nmodern condensed matter physics, Dirac semimetals and atomically-thin layered\nmaterials. When these trends meet again in transition metal compounds, which\npossess spin and orbital degrees of freedom and strong electron correlations,\nmore exotic phenomena are expected to emerge in the cross section of\ntopological states of matter and Mott physics. Here, we show by using ab initio\ncalculations that a monolayer form of transition metal trichalcogenides (TMTs),\nwhich has a honeycomb network of transition metal cations, may exhibit multiple\nDirac cones with tunable gaps in the electronic structure. Furthermore, we\nelucidate that electron correlations and carrier doping turn the multiple-Dirac\nsemimetal into a topological ferromagnet with high Chern number. Our findings\nraise the honeycomb-monolayer TMTs to a new paradigm to explore correlated\nDirac electrons and topologically-nontrivial magnetism. In turn, the unique\nwide-ranging properties of the materials will deliver new building blocks for\natomically thin heterostructures.",
        "positive": "Square Moir\u00e9 Superlattices in Twisted Two-Dimensional Halide\n  Perovskites: Moir\\'e superlattices have emerged as a new platform for studying strongly\ncorrelated quantum phenomena, but these systems have been largely limited to\nvan der Waals layer two-dimensional (2D) materials. Here we introduce moir\\'e\nsuperlattices leveraging ultra-thin, ligand-free halide perovskites,\nfacilitated by ionic interactions. Square moir\\'e superlattices with varying\nperiodic lengths are clearly visualized through high-resolution transmission\nelectron microscopy. Twist-angle-dependent transient photoluminescence\nmicroscopy and electrical characterizations indicate the emergence of localized\nbright excitons and trapped charge carriers near a twist angle of ~10{\\deg}.\nThe localized excitons are accompanied by enhanced exciton emission, attributed\nto an increased oscillator strength by a theoretically forecasted flat band.\nThis work illustrates the potential of extended ionic interaction in realizing\nmoir\\'e physics at room temperature, broadening the horizon for future\ninvestigations."
    },
    {
        "anchor": "Optical Characterizations and Electronic Devices of Nearly Pure (10,5)\n  Single-Walled Carbon Nanotubes: It remains an elusive goal to achieve high performance single-walled carbon\nnanotube (SWNTs) field effect transistors (FETs) comprised of only single\nchirality SWNTs. Many separation mechanisms have been devised and various\ndegrees of separation demonstrated, yet it is still difficult to reach the goal\nof total fractionation of a given nanotube mixture into its single chirality\ncomponents. Chromatography has been reported to separate small SWNTs (diameter\nless than 0.9nm) according to their diameter, chirality and length. The\nseparation efficiency decreased with increasing tube diameter by using ssDNA\nsequence d(GT)n (n=10-45). Here we report our result on the separation of\nsingle chirality (10,5) SWNTs (diameter = 1.03nm) from HiPco tubes with ion\nexchange chromatography. The separation efficiency was improved by using a new\nDNA sequence (TTTA)3T which can recognize SWNTs with the specific chirality\n(10,5). The chirality of the separated tubes was examined by optical\nabsorption, Raman, photoluminescence excitation/emission and electrical\ntransport measurement. All spectroscopic methods gave single peak of (10,5)\ntubes. The purity was 99% according to the electrical measurement. The FETs\ncomprised of separated SWNTs in parallel gave Ion/Ioff ratio up to 106 owning\nto the single chirality enriched (10,5) tubes. This is the first time that SWNT\nFETs with single chirality SWNTs were achieved. The chromatography method has\nthe potential to separate even larger diameter semiconducting SWNTs from other\nstarting material for further improving the performance of the SWNT FETs.",
        "positive": "Determining Perpendicular Magnetic Anisotropy in Fe/MgO/Fe Magnetic\n  Tunnel Junction: A DFT-Based Spin-Orbit Torque Method: In our JunPy package, we have combined the first-principles calculated\nself-consistent Hamiltonian with divide-and-conquer technique to successfully\ndetermine the magnetic anisotropy (MA) in an Fe/MgO/Fe magnetic tunnel junction\n(MTJ). We propose a comprehensive analytical derivation to clarify the crucial\nroles of spin-orbit coupling that mediates the exchange and spin-orbit\ncomponents of spin torque, and the kinetic and spin-orbit components of spin\ncurrent accumulation. The angular dependence of cumulative spin-orbit torque\n(SOT) indicates a uniaxial MA corresponding to the out-of-plane rotations of\nmagnetic moments of the free Fe layers. Different from the conventional MA\nenergy calculation and the phenomenological theory for a whole MTJ, our results\nprovide insight into the orbital-resolved SOT for atomistic spin dynamics\nsimulation in emergency complex magnetic heterojunctions."
    },
    {
        "anchor": "Resonant interatomic Auger transition in chalcopyrite CuInSe2: The interatomic Auger transitions in compounds containing atomic components\nwith core levels close in energy are studied theoretically and experimentally.\nThe Coulomb transitions of a hole between such levels lead to a resonant\nenhancement of the Auger spectra (with respect to the energy difference between\nthe levels). Interatomic Auger transitions involving high lying levels are\nformed by shaking up electrons due to the dynamic field of photo holes produced\nduring the transition. These effects were observed experimentally in XPS and\nAuger spectra of CuInSe2 type materials.",
        "positive": "Self-interaction corrected SCAN functional for molecules and solids in\n  the numeric atom-center orbital framework: Semilocal density-functional approximations (DFAs), including the\nstate-of-the-art SCAN functional, are plagued by the self-interaction error\n(SIE). While this error is explicitly defined only for one-electron systems, it\nhas inspired the self-interaction correction method proposed by Perdew and\nZunger (PZ-SIC), which has shown promise in mitigating the many-electron SIE.\nHowever, the PZ-SIC method is known for its significant numerical instability.\nIn this study, we introduce a novel constraint that facilitates self-consistent\nlocalization of the SIC orbitals in the spirit of Edmiston-Ruedenberg orbitals\n[Rev. Mod. Phys. 35, 457 (1963)]. Our practical implementation within the\nall-electron numeric atom-centered orbitals code FHI-aims guarantees efficient\nand stable convergence of the self-consistent PZ-SIC equations for both\nmolecules and solids. We further demonstrate that our PZ-SIC approach\neffectively mitigates the SIE in the meta-GGA SCAN functional, significantly\nimproving the accuracy for ionization potentials, charge-transfer energies, and\nband gaps for a diverse selection of molecules and solids. However, our PZ-SIC\nmethod does have its limitations. It can not improve the already accurate SCAN\nresults for properties such as cohesive energies, lattice constants, and bulk\nmodulus in our test sets. This highlights the need for new-generation DFAs with\nmore comprehensive applicability."
    },
    {
        "anchor": "Thermo-mechanical behavior of surface acoustic waves in ordered arrays\n  of nanodisks studied by near infrared pump-probe diffraction experiments: The ultrafast thermal and mechanical dynamics of a two-dimensional lattice of\nmetallic nano-disks has been studied by near infrared pump-probe diffraction\nmeasurements, over a temporal range spanning from 100 fs to several\nnanoseconds. The experiments demonstrate that, in these systems, a\ntwo-dimensional surface acoustic wave (2DSAW), with a wavevector given by the\nreciprocal periodicity of the array, can be excited by ~120 fs Ti:sapphire\nlaser pulses. In order to clarify the interaction between the nanodisks and the\nsubstrate, numerical calculations of the elastic eigenmodes and simulations of\nthe thermodynamics of the system are developed through finite-element analysis.\nAt this light, we unambiguously show that the observed 2DSAW velocity shift\noriginates from the mechanical interaction between the 2DSAWs and the\nnano-disks, while the correlated 2DSAW damping is due to the energy radiation\ninto the substrate.",
        "positive": "Monte Carlo Simulation for the Formation and Growth of Low\n  Dimensionality Phases During Underpotential Deposition of Ag on Au(100): Simulation studies are undertaken for the system Ag/Au(100) by means of grand\ncanonical Monte Carlo applied to a large lattice system. The interactions are\ncalculated using the embedded atom model. The formation of adsorbed Ag phases\nof low dimensionality on Ag(100) is investigated and the influence of surface\ndefects on the shape of the adsorption isotherms is studied. The results of the\nsimulations are discussed in the light of experimental information available\nfrom electrochemical measurements."
    },
    {
        "anchor": "Origin of the large positive magnetoresistance in Ge1-xMnx granular thin\n  films: GeMn granular thin films are a unique and promising material for spintronics\napplications due to large positive magnetoresistance (MR). Previous studies on\nGeMn have suggested that the large MR is related to nanospinodal decomposition\nof GeMn into Mn-rich ferromagnetic nanoparticles and Mn-poor paramagnetic\nmatrix. However, its microscopic origin of the MR has not been clarified yet.\nHere, using X-ray magnetic circular dichroism (XMCD), which is extremely\nsensitive to the local magnetic state of each atom, we investigate the magnetic\nproperties of the nanoparticles and the matrix in GeMn separately. We find that\nthe MR ratio is proportional to the product of the magnetizations originating\nfrom the nanoparticles and the matrix. This result indicates that\nspin-polarized holes in the nanoparticles penetrate into the matrix and that\nthese holes undergo spin-disorder magnetic scattering by the paramagnetic Mn\natoms in the matrix, which induces the large MR.",
        "positive": "Dependence of the Spin Transfer Torque Switching Current Density on the\n  Exchange Stiffness Constant: We investigate the dependence of the switching current density on the\nexchange stiffness constant in the spin transfer torque magnetic tunneling\njunction structure with micromagnetic simulations. Since the widely accepted\nanalytic expression of the switching current density is based on the macro-spin\nmodel, there is no dependence of the exchange stiffness constant. When the\nswitching is occurred, however, the spin configuration forms C-, S-type, or\ncomplicated domain structures. Since the spin configuration is determined by\nthe shape anisotropy and the exchange stiffness constant, the switching current\ndensity is very sensitive on their variations. It implies that there are more\nrooms for the optimization of the switching current density with by controlling\nthe exchange stiffness constant, which is determined by composition and the\ndetail fabrication processes."
    },
    {
        "anchor": "Switching dynamics between metastable ordered magnetic state and\n  nonmagnetic ground state - A possible mechanism for photoinduced\n  ferromagnetism -: By studying the dynamics of the metastable magnetization of a statistical\nmechanical model we propose a switching mechanism of photoinduced\nmagnetization. The equilibrium and nonequilibrium properties of the Blume-Capel\n(BC) model, which is a typical model exhibiting metastability, are studied by\nmean field theory and Monte Carlo simulation. We demonstrate reversible changes\nof magnetization in a sequence of changes of system parameters, which would\nmodel the reversible photoinduced magnetization. Implications of the calculated\nresults are discussed in relation to the recent experimental results for\nprussian blue analogs.",
        "positive": "A First-Principles Study of Defects and Adatoms in Silicon Carbide\n  Honeycomb Structures: We present a study of mechanical, electronic and magnetic properties of two\ndimensional (2D), monolayer of silicon carbide (SiC) in honeycomb structure and\nits quasi 1D armchair nanoribbons using first-principles plane wave method. In\norder to reveal dimensionality effects, a brief study of 3D bulk and 1D atomic\nchain of SiC are also included. Calculated bond-lengths, cohesive energies,\ncharge transfers and band gaps display a clear dimensionality effect. The\nstability analysis based on the calculation of phonon frequencies indicates\nthat 2D SiC monolayer is stable in planar geometry. We found that 2D SiC\nmonolayer in honeycomb structure and its bare and hydrogen passivated\nnanoribbons are ionic, non-magnetic, wide band gap semiconductors. The band gap\nis further increased upon self-energy corrections. The mechanical properties\nare investigated using the strain energy calculations. The effect of various\nvacancy defects, adatoms and substitutional impurities on electronic and\nmagnetic properties in 2D SiC monolayer and in its armchair nanoribbons are\nalso investigated. Some of these vacancy defects and impurities, which are\nfound to influence physical properties and attain magnetic moments, can be used\nto functionalize SiC honeycomb structures."
    },
    {
        "anchor": "Tunable discrete scale invariance in transition-metal pentatelluride\n  flakes: Log-periodic quantum oscillations discovered in transition-metal\npentatelluride give a clear demonstration of discrete scale invariance (DSI) in\nsolid-state materials. The peculiar phenomenon is convincingly interpreted as\nthe presence of two-body quasi-bound states in a Coulomb potential. However,\nthe modifications of the Coulomb interactions in many-body systems having a\nDirac-like spectrum are not fully understood. Here, we report the observation\nof tunable log-periodic oscillations and DSI in ZrTe5 and HfTe5 flakes. By\nreducing the flakes thickness, the characteristic scale factor is tuned to a\nmuch smaller value due to the reduction of the vacuum polarization effect. The\ndecreasing of the scale factor demonstrates the many-body effect on the DSI,\nwhich has rarely been discussed hitherto. Furthermore, the cut-offs of\noscillations are quantitatively explained by considering the Thomas-Fermi\nscreening effect. Our work clarifies the many-body effect on DSI and paves a\nway to tune the DSI in quantum materials.",
        "positive": "Screening nature of the van der Waals density functional method: A\n  review and analysis of the many-body physics foundation: We review the screening nature and many-body physics foundation of the van\nder Waals density functional (vdW-DF) method, a systematic approach to\nconstruct truly nonlocal exchange-correlation energy density functionals. To\nthat end we define and focus on a class of consistent vdW-DF versions that\nadhere to the Lindhard screening logic of the full method formulation. The\nconsistent-exchange vdW-DF-cx version and its spin extension represent the\nfirst examples of this class; In general, consistent vdW-DFs reflect a\nconcerted expansion of a formal recast of the adiabatic-connection formula, an\nexponential summation of contributions to the local-field response, and the\nDyson equation. We argue that the screening emphasis is essential because the\nexchange-correlation energy reflects an effective electrodynamics set by a\nlong-range interaction. Two consequences are that 1) there are, in principle,\nno wiggle room in how one balances exchange and correlation, for example, in\nvdW-DF-cx, and that 2) consistent vdW-DFs have a formal structure that allows\nthem to incorporate vertex-correction effects, at least in the case of levels\nthat experience recoil-less interactions (for example, near the Fermi surface).\nWe explore the extent to which the strictly nonempirical vdW-DF-cx formulation\ncan serve as a systematic extension of the constraint-based semilocal\nfunctionals. For validation, we provide a complete survey of vdW-DF-cx\nperformance for broad molecular processes and comparing to the\nquantum-chemistry calculations that are summarized in that paper. We also\nprovide new vdW-DF-cx results for metal surface energies and work functions\nthat we compare to experiment. Finally, we use the screening insight to\nseparate the vdW-DF nonlocal-correlation term and present tools to compute and\nmap the binding signatures."
    },
    {
        "anchor": "Predicting band gaps and band-edge positions of oxide perovskites using\n  DFT and machine learning: Density functional theory within the local or semilocal density\napproximations (DFT-LDA/GGA) has become a workhorse in electronic structure\ntheory of solids, being extremely fast and reliable for energetics and\nstructural properties, yet remaining highly inaccurate for predicting band gaps\nof semiconductors and insulators. Accurate prediction of band gaps using\nfirstprinciples methods is time consuming, requiring hybrid functionals,\nquasi-particle GW, or quantum Monte Carlo methods. Efficiently correcting\nDFT-LDA/GGA band gaps and unveiling the main chemical and structural factors\ninvolved in this correction is desirable for discovering novel materials in\nhigh-throughput calculations. In this direction, we use DFT and machine\nlearning techniques to correct band gaps and band-edge positions of a\nrepresentative subset of ABO3 perovskite oxides. Relying on results of HSE06\nhybrid functional calculations as target values of band gaps, we find a\nsystematic band gap correction of ~1.5 eV for this class of materials, where ~1\neV comes from downward shifting the valence band and ~0.5 eV from uplifting the\nconduction band. The main chemical and structural factors determining the band\ngap correction are determined through a feature selection procedure.",
        "positive": "Non-linear phenomena in electrical circuits: Simulation of non-linear\n  relativistic field theory and possible applications: We propose the non-accelerator non-low-temperature simulator of quantum-field\neffects which is based on the feeder circuits with the special feedback. By\nmeans of it one can study the field models which contain fundamental concepts\nin the modern field theory but do not exist in nature in a separate form.\nBesides, several field phenomena might find technological applications by\nvirtue of the electrical analogy."
    },
    {
        "anchor": "Towards Ultra Low Cobalt Cathodes: A High Fidelity Computational Phase\n  Search of Layered Li-Ni-Mn-Co Oxides: Layered Li(Ni,Mn,Co,)O$_2$ (NMC) presents an intriguing ternary alloy design\nspace for optimization as a cathode material in Li-ion batteries. Recently, the\nhigh cost and resource limitations of Co have added a new design constraint and\nhigh Ni-containing NMC alloys have gained enormous attention despite possible\nperformance trade-offs. It is not fully understood if this material space is a\ndisordered solid solution at room temperature and any arbitrary combination can\nbe used or if there exist distinct transition metal orderings to which\nmeta-stable solid solutions will decay during cycling and affect performance.\nHere, we present a high fidelity computational search of the ternary phase\ndiagram with an emphasis on high-Ni, and thus low Co, containing compositional\nphases to understand the room temperature stability of the ordered and\ndisordered solid solution phases. This is done through the use of density\nfunctional theory training data fed into a reduced order model Hamiltonian that\naccounts for effective electronic and spin interactions of neighboring\ntransition metal atoms at various lengths in a background of fixed composition\nand position lithium and oxygen atoms. This model can then be solved to include\nfinite temperature thermodynamics into a convex hull analysis to understand the\nregions of ordered and disordered solid solution as well the transition metal\norderings within the ordered region of the phase diagram. We find that for the\nmajority of transition metal compositions of the layered material, specifically\nmedium to high-Ni content, prefer transition metal ordering and predict the\ncollection of preferred compositions in the ordered region.",
        "positive": "Large Spin Hall Effect in an Amorphous Binary Alloy: We investigate the spin Hall effect of W-Hf thin films, which exhibit a phase\ntransition from a segregated phase mixture to an amorphous alloy below 70% W.\nThe spin Hall angle was determined with a planar harmonic Hall voltage\ntechnique. Due to the accompanying jump in resistivity, the spin Hall angle\nshows a pronounced maximum at the composition of the phase transition. The spin\nHall conductivity does, however, reduce from W to Hf with a weak discontinouity\nacross the phase transition. The maximum spin Hall angle of $\\theta_\\mathrm{SH}\n= -0.25$ is obtained for amorphous W$_{0.7}$Hf$_{0.3}$. A detailed comparison\nwith spin Hall conductivities calculated from first principles for hcp, fcc,\nand bcc solid solutions provides valuable insight into the alloying physics of\nthis binary system."
    },
    {
        "anchor": "Interpreting current-induced spin polarization in topological insulator\n  surface states: Several recent experiments on three-dimensional topological insulators claim\nto observe a large charge current-induced non-equilibrium ensemble spin\npolarization of electrons in the helical surface state. We present a\ncomprehensive criticism of such claims, using both theory and experiment:\nFirst, we clarify the interpretation of quantities extracted from these\nmeasurements by deriving standard expressions from a Boltzmann transport\nequation approach in the relaxation-time approximation at zero and finite\ntemperature to emphasize our assertion that, despite high in-plane spin\nprojection, obtainable current-induced ensemble spin polarization is minuscule.\nSecond, we use a simple experiment to demonstrate that magnetic field-dependent\nopen-circuit voltage hysteresis (identical to those attributed to\ncurrent-induced spin polarization in topological insulator surface states) can\nbe generated in analogous devices where current is driven through thin films of\na topologically-trivial metal. This result *ipso facto* discredits the naive\ninterpretation of previous experiments with TIs, which were used to claim\nobservation of helicity, i.e. spin-momentum locking in the\ntopologically-protected surface state.",
        "positive": "Entropic signatures of the skyrmion lattice phase in MnSi1-xAlx and\n  Fe1-yCoySi: The entropic signatures of magnetic phase transitions in the skyrmion lattice\nhost compounds MnSi0.962Al0.038 and Fe0.7Co0.3Si were investigated through low\nfield magnetization and ac susceptibility measurements. These data indicate\nthat the conical to skyrmion transition that occurs with the application of\nmagnetic field in MnSi0.962Al0.038 is characterized by clear discontinuity in\nthe magnetic entropy as expected for first order topological phase transition.\nThese same magnetoentropic features are negligibly small in isostructural\nFe0.7Co0.3Si due to the level of chemical substitution related disorder and\ndifferences in the spin dynamics (range and timescales). Despite the obvious\nsimilarities in the magnetic structures of these two compounds, the transitions\nbetween these phases is substantially different indicating a surprising\nnon-universality to the magnetic phase transitions in this class of materials."
    },
    {
        "anchor": "Effects of interface oxygen vacancies on electronic bands of\n  FeSe/SrTiO3(001): Modifications of the electronic bands of thin FeSe films due to oxygen\nvacancies in the supporting SrTiO 3 (001) substrate - and the interplay with\nspin-orbit coupling, magnetism, and epitaxy - are investigated by\nfirst-principles supercell calculations. Unfolded (k-projected) bands show that\nthe oxygen vacancies both provide electron doping to the interface FeSe layer\nand also have notable effects on the details of the bands around the Fermi\nlevel, including renormalizing the width of the Fe-3d band near the Fermi level\nby a factor of about 0.6, and causing a splitting of ~40 meV at the M point for\nthe checkerboard antiferromagnetic configuration. For an FeSe bilayer, the\nmodifications to the bands are mainly limited to the interface FeSe layer.\nWhile spin-orbit-coupling induced band splittings of ~30 meV at M for the ideal\nFeSe/SrTiO3 (001) interfaces are comparable to the splitting due to oxygen\nvacancies, the effects are not simply additive. Calculations and comparison to\nour scanning tunneling microscopy images of MBE-grown FeSe films on SrTiO3\n(001) suggest that a common defect may be Se bound to an oxygen vacancy at the\ninterface",
        "positive": "Evidence for anisotropic polar nanoregions in relaxor PMN: A neutron\n  study of the elastic constants and anomalous TA phonon damping: We use neutron scattering to characterize the acoustic phonons in the relaxor\nPMN and demonstrate the presence of an anisotropic damping mechanism directly\nrelated to short-range, polar correlations. For a large range of temperatures\nabove Tc ~ 210, K, where dynamic polar correlations exist, acoustic phonons\npropagating along [1\\bar{1}0] and polarized along [110] (TA2 phonons) are\noverdamped and softened across most of the Brillouin zone. By contrast,\nacoustic phonons propagating along [100] and polarized along [001] (TA1\nphonons) are overdamped and softened for only a limited range of wavevectors.\nThe anisotropy and temperature dependence of the acoustic phonon energy\nlinewidth are directly correlated with the elastic diffuse scattering,\nindicating that polar nanoregions are the cause of the anomalous behavior. The\ndamping and softening vanish for q -> 0, i.e. for long-wavelength acoustic\nphonons, which supports the notion that the anomalous damping is a result of\nthe coupling between the relaxational component of the diffuse scattering and\nthe harmonic TA phonons. Therefore, these effects are not due to large changes\nin the elastic constants with temperature because the elastic constants\ncorrespond to the long-wavelength limit. We compare the elastic constants we\nmeasure to those from Brillouin scattering and to values reported for pure PT.\nWe show that while the values of C44 are quite similar, those for C11 and C12\nare significantly less in PMN and result in a softening of (C11-C12) over PT.\nThere is also an increased elastic anisotropy (2C44/(C11-C12)) versus that in\nPT. These results suggest an instability to TA2 acoustic fluctuations in\nrelaxors. We discuss our results in the context of the debate over the\n\"waterfall\" effect and show that they are inconsistent with TA-TO phonon\ncoupling or other models that invoke the presence of a second optic mode."
    },
    {
        "anchor": "Gel-Based Morphological Design of Zirconium Metal-organic Frameworks: The ability of metal-organic frameworks (MOFs) to gelate under specific\nsynthetic conditions opens up new opportunities in the preparation and shaping\nof hierarchically porous MOF monoliths, which could be directly implemented for\ncatalytic and adsorptive applications. In this work, we present the first\nexamples of xero- or aerogel monoliths consisting solely of nanoparticles of\nseveral prototypical Zr4+-based MOFs: UiO-66-X (X = H, NH2, NO2, (OH)2),\nUiO-67, MOF-801, MOF-808 and NU-1000. High reactant and water concentrations\nduring synthesis were observed to induce the formation of gels, which were\nconverted to monolithic materials by drying in air or supercritical CO2.\nElectron microscopy, combined with N2 physisorption experiments, was used to\nshow that an irregular nanoparticle packing leads to pure MOF monoliths with\nhierarchical pore systems, featuring both intraparticle micropores and\ninterparticle mesopores. Finally, UiO-66 gels were shaped into monolithic\nspheres of 600 micrometer diameter using an oil-drop method, creating promising\ncandidates for packed-bed catalytic or adsorptive applications, where\nhierarchical pore systems can greatly mitigate mass transfer limitations.",
        "positive": "X-ray absorption branching ratio in actinides: LDA+DMFT approach: To investigate the x-ray absorption (XAS) branching ratio from the core 4d to\nvalence 5f states, we set up a theoretical framework by using a combination of\ndensity functional theory in the local density approximation and Dynamical Mean\nField Theory (LDA+DMFT), and apply it to several actinides. The results of the\nLDA+DMFT reduces to the band limit for itinerant systems and to the atomic\nlimit for localized f electrons, meaning a spectrum of 5f itinerancy can be\ninvestigated. Our results provides a consistent and unified view of the XAS\nbranching ratio for all elemental actinides, and is in good overall agreement\nwith experiments."
    },
    {
        "anchor": "Oxygen reduction reactions on pure and nitrogen-doped graphene: a\n  first-principles modeling: Based on first principles density functional theory calculations we explored\nenergetics of oxygen reduction reaction over pristine and nitrogen-doped\ngraphene with different amounts of nitrogen doping. The process of oxygen\nreduction requires one more step then same reaction catalyzed by metals.\nResults of calculations evidence that for the case of light doped graphene\n(about 4% of nitrogen) energy barrier for each step is lower than for the same\nprocess on Pt surface. In contrast to the catalysis on metal surface the\nmaximal coverage of doped graphene is lower and depends on the corrugation of\ngraphene. Changes of the energy barriers caused by oxygen load and corrugation\nare also discussed.",
        "positive": "Revealing the spin and symmetry properties of the buried Co2MnSi/MgO\n  interface by low energy spin-resolved photoemission: We present a novel approach to study the spin and symmetry electronic\nproperties of buried interfaces using low-energy spin-resolved photoemission\nspectroscopy. We show that this method is sensitive to interfaces buried below\nmore than 20ML (~4nm) MgO, providing a powerful tool for the non-destructive\ncharacterization of spintronics interfaces. As a demonstration, we apply this\ntechnique to characterize the Co2MnSi/MgO interface, a fundamental building\nblock of state-of-the-art magnetic tunnel junctions based on Heusler compounds.\nWe find that a surface state with {\\Delta}1 symmetry and minority spin\ncharacter dominating the electronic structure of the bare Co2MnSi(100) surface\nis quenched at the Co2MnSi(100)/MgO interface. As a result, the interface\nspin-dependent electronic structure resembles the theoretically expected\nCo2MnSi bulk band structure, with majority spin electronic states of both\n{\\Delta}1 and {\\Delta}5 symmetry. Furthermore we find an additional\nthermally-induced contribution in the minority channel, mirroring the\n{\\Delta}1/{\\Delta}5 asymmetry of the majority channel."
    },
    {
        "anchor": "Structural relaxation and Jahn-Teller distortion of LaMnO3 (001) surface: We studied in detail the structural relaxation and Jahn-Teller distortion in\nLaMnO3 (001) surface of the orthorhombic phase by means of classical atomistic\nsimulation. It is found that MnO2-terminated surface is more energetically\nfavorable than LaO-terminated surface by 0.34 eV. The standard deviation of\nMn-O bond lengths of MnO6 octahedra and Jahn-Teller distortion oscillate in\nLaMnO3 (001) surface. Our simulated atomic displacements in the surface are\ncompared with some ab initio studies.",
        "positive": "Giant room temperature interface spin Hall and inverse spin Hall effects: The spin Hall angle (SHA) is a measure of the efficiency with which a\ntransverse spin current is generated from a charge current by the spin-orbit\ncoupling and disorder in the spin Hall effect (SHE). In a study of the SHE for\na Pt$|$Py (Py=Ni$_{80}$Fe$_{20}$) bilayer using a first-principles scattering\napproach, we find a SHA that increases monotonically with temperature and is\nproportional to the resistivity for bulk Pt. By decomposing the room\ntemperature SHE and inverse SHE currents into bulk and interface terms, we\ndiscover a giant interface SHA that dominates the total inverse SHE current\nwith potentially major consequences for applications."
    },
    {
        "anchor": "Role of structural defects on exchange bias in the epitaxial CoO/Co\n  system: We have studied the influence of non-magnetic defects throughout the\nantiferromagnet Co_{1-y}O on the exchange bias (EB) in epitaxially grown\nCo_{1-y}O/Co bilayers. These defects are either substitutional or structural\n(twin boundaries and surface morphology) which both lead to an increase of the\nEB-field. We find a dominance of twin boundaries over surface morphology\n(roughness) in enhancing EB which is consistent with the domain state model for\nexchange bias. In contrast, the crystal orientation of the Co_{1-y}O layer does\nnot show a significant effect on the EB in this system.",
        "positive": "Calculating the Hyperfine Tensors for Group-IV Impurity-Vacancy Centers\n  in Diamond: A Hybrid Density-Functional Theory Approach: The hyperfine interaction is an important probe for understanding the\nstructure and symmetry of defects in a semiconductor. Density-functional theory\nhas shown that it can provide useful first-principles predictions for both the\nhyperfine tensor and the hyperfine constants that arise from it. Recently there\nhas been great interest in using group-IV impurity-vacancy color centers X$V^-$\n(where X = Si, Ge, Sn, or Pb and $V$ is a carbon vacancy) for important\napplications in quantum computing and quantum information science. In this\npaper, we have calculated the hyperfine tensors for these X$V^-$ color centers\nusing the HSE06 screened Hartree-Fock hybrid exchange-correlation functional\nwith the inclusion of core electron spin polarization. We have compared our\nresults to calculations which only use the PBE exchange-correlation functional\nwithout the inclusion of core electron spin polarization and we have found our\nresults are in very good agreement with available experimental results.\nFinally, we have theoretically shown that these X$V^-$ color centers exhibit a\nJahn-Teller distortion which explains the observed anisotropic distribution of\nthe hyperfine constants among the neighboring $^{13}$C nuclear spins."
    },
    {
        "anchor": "Quantitative determination of interlayer electronic coupling at various\n  critical points in bilayer MoS2: Tailoring interlayer coupling has emerged as a powerful tool to tune the\nelectronic structure of van der Waals (vdW) bilayers. One example is the usage\nof the moire pattern to create controllable two-dimensional electronic\nsuperlattices through the configurational dependence of interlayer electronic\ncouplings. This approach has led to some remarkable discoveries in twisted\ngraphene bilayers, and transition metal dichalcogenide (TMD) homo- and\nhetero-bilayers. However, a largely unexplored factor is the interlayer\ndistance, d, which can impact the interlayer coupling strength exponentially.\nIn this letter, we quantitatively determine the coupling strengths as a\nfunction of interlayer spacing at various critical points of the Brillouin zone\nin bilayer MoS2. The exponential dependence of the coupling parameter on the\ngap distance is demonstrated. Most significantly, we achieved a 280%\nenhancement of K-valley coupling strength with an 8% reduction of the vdW gap,\npointing to a new strategy in designing a novel electronic system in vdW\nbilayers.",
        "positive": "Predictive Models based on Deep Learning Algorithms for Tensile\n  Deformation of AlCoCuCrFeNi High-entropy alloy: High-entropy alloys (HEAs) stand out between multi-component alloys due to\ntheir attractive microstructures and mechanical properties. In this\ninvestigation, molecular dynamics (MD) simulation and machine learning were\nused to ascertain the deformation mechanism of AlCoCuCrFeNi HEAs under the\ninfluence of temperature, strain rate, and grain sizes. First, the MD\nsimulation shows that the yield stress decreases significantly as the strain\nand temperature increase. In other cases, changes in strain rate and grain size\nhave less effect on mechanical properties than changes in strain and\ntemperature. The alloys exhibited superplastic behavior under all test\nconditions. The deformity mechanism discloses that strain and temperature are\nthe main sources of beginning strain, and the shear bands move along the\nuniaxial tensile axis inside the workpiece. Furthermore, the fast phase shift\nof inclusion under mild strain indicates the relative instability of the\ninclusion phase of HCP. Ultimately, the dislocation evolution mechanism shows\nthat the dislocations are transported to free surfaces under increased strain\nwhen they nucleate around the grain boundary. Surprisingly, the ML prediction\nresults also confirm the same characteristics as those confirmed from the MD\nsimulation. Hence, the combination of MD and ML reinforces the confidence in\nthe findings of mechanical characteristics of HEA. Consequently, this\ncombination fills the gaps between MD and ML, which can significantly save time\nhuman power and cost to conduct real experiments for testing HEA deformation in\npractice."
    },
    {
        "anchor": "Hubbard-$U$ corrected Hamiltonians for non-self-consistent random-phase\n  approximation total-energy calculations: A study of ZnS, TiO$_2$, and NiO: In non-self-consistent calculations of the total energy within the\nrandom-phase approximation (RPA) for electronic correlation, it is necessary to\nchoose a single-particle Hamiltonian whose solutions are used to construct the\nelectronic density and non-interacting response function. Here we investigate\nthe effect of including a Hubbard-$U$ term in this single-particle Hamiltonian,\nto better describe the on-site correlation of 3$d$ electrons in the transition\nmetal compounds ZnS, TiO$_2$ and NiO. We find that the RPA lattice constants\nare essentially independent of $U$, despite large changes in the underlying\nelectronic structure. We further demonstrate that the non-self-consistent RPA\ntotal energies of these materials have minima at nonzero $U$. Our RPA\ncalculations find the rutile phase of TiO$_2$ to be more stable than anatase\nindependent of $U$, a result which is consistent with experiments and\nqualitatively different to that found from calculations employing $U$-corrected\n(semi)local functionals. However we also find that the +$U$ term cannot be used\nto correct the RPA's poor description of the heat of formation of NiO.",
        "positive": "Composition-tunable magnon-polaron anomalies in spin Seebeck effects in\n  epitaxial Bi$_x$Y$_{3-x}$Fe$_{5}$O$_{12}$ films: We have investigated hybridized magnon-phonon excitation (magnon polarons) in\nspin Seebeck effects (SSEs) in Bi$_x$Y$_{3-x}$Fe$_{5}$O$_{12}$\n(Bi$_x$Y$_{3-x}$IG; $x=0$, $0.5$, and $0.9$) films with Pt contact. We observed\nsharp peak structures in the magnetic field $H$ dependence of the longitudinal\nSSE (LSSE) voltages, which appear when the phonon dispersions are tangential to\nthe magnon dispersion curve in Bi$_x$Y$_{3-x}$IG. By increasing the Bi amount\n$x$, the peak fields in the LSSE shift toward lower $H$ values due to the\nreduction of the sound velocities in Bi$_x$Y$_{3-x}$IG. We also measured the\nSSE in a nonlocal configuration and found that magnon-polaron anomalies appear\nwith different signs and intensities. Our result shows composition-tunability\nof magnon-polaron anomalies and provides a clue to further unravel the physics\nof magnon-polaron SSEs."
    },
    {
        "anchor": "Lifetime of coexisting sub-10 nm zero-field skyrmions and antiskyrmions: Magnetic skyrmions have raised high hopes for future spintronic devices. For\nmany applications it would be of great advantage to have more than one\nmetastable particle-like texture available. The coexistence of skyrmions and\nantiskyrmions has been proposed in inversion symmetric magnets with exchange\nfrustration. However, so far only model systems have been studied and the\nlifetime of coexisting metastable topological spin structures has not been\nobtained. Here, we predict that skyrmions and antiskyrmions with diameters\nbelow 10 nm can coexist at zero magnetic field in a Rh/Co bilayer on the\nIr(111) surface -- an experimentally feasible system. We show that the\nlifetimes of metastable skyrmions and antiskyrmions in the ferromagnetic ground\nstate are above one hour for temperatures up to 75 K and 48 K, respectively.\nThe entropic contribution to the nucleation and annihilation rates differs for\nskyrmions and antiskyrmions. This opens the route to thermally activated\ncreation of coexisting skyrmions and antiskyrmions in frustrated magnets with\nDzyaloshinskii-Moriya interaction.",
        "positive": "Peculiarities of polarization switching in ferroelectric semiconductors\n  with charged inhomogeneities: We have proposed the phenomenological description of polarization switching\npeculiarities in ferroelectric semiconductors with charged defects and\nprevailing extrinsic conductivity. Exactly we have modified Landau-Ginsburg\napproach shown that the macroscopic state of the aforementioned inhomogeneous\nsystem can be described by three coupled equations for three order parameters.\nBoth the experimentally observed coercive field values well below the\nthermodynamic one and the various hysteresis loop deformations (minor,\nconstricted and double loops) have been obtained in the framework of our model.\nThe obtained results qualitatively explain the ferroelectric switching in such\nbulk ferroelectric materials as SBN single crystals doped with Ce, PZT films\ndoped with Nd and La- doped PZT ceramics."
    },
    {
        "anchor": "Prediction of Extraordinary Magnetoresistance in Janus Monolayer MoTeB2: Based on first-principles calculations, we studied the geometric\nconfiguration, stability and electronic structure of the two-dimensional Janus\nMoTeB2. The MoTeB2 monolayer is semimetal, and its attractive electronic\nstructure reveals the perfect electron-hole compensation. Moreover, the\nelectron-type and hole-type bands of the MoTeB2 monolayer are easily adjustable\nby external stain and charge doping, such as the switch of carrier polarity by\ncharge doping, and the metal-semiconductor transition under tensile stain.\nThese properties allow the MoTeB2 monolayer to be a controllable\ntwo-dimensional material with extraordinary large magnetoresistance in magnetic\nfield.",
        "positive": "Mechanism responsible for initiating room temperature ferromagnetism and\n  spin polarized current in diluted magnetic oxides: The main obstacles in realizing diluted magnetic oxide (DMO) in spintronics\nare the unknown electronic structures associated with its high TC\nferromagnetism and spin polarized current and how to manipulate desired\nelectronic structures by fabrication techniques. We demonstrate that fine-tuned\nelectronic structures and band structures can be modified to initiate DMO\nproperties. Interestingly, in the semiconducting state, the doped Co ions and\noxygen vacancies contribute non-negligible magnetic moments; and the magnetic\ncoupling between these moments is mediated by the localized carriers via highly\nspin polarized hopping transport. These results unravel the myth of the origin\nof spintronic characteristics with desirable electronic states; thereby\nreopening the door for future applications."
    },
    {
        "anchor": "Improved Muller approximate solution of the pull-off of a sphere from a\n  viscoelastic substrate: The detachment of a sphere from a viscoelastic substrate is clearly a\nfundamental problem. In the case viscoelastic dissipation is concentrated at\nthe contact edge, and the work of adhesion follows a quite popular simplified\nmodel, Muller has suggested an approximate solution, which however is based on\nan empirical observation. We revisit Muller's solution and show it leads to\nvery poor fitting of the actual full numerical results, particularly for the\nradius of contact at pull-off, and we suggest an improved fitting of the\npull-off which works extremely well over a very wide range of withdrawing\nspeeds, and correctly converges to the JKR value at very low speeds.",
        "positive": "Ultra-Wide Bandgap Ga$_2$O$_3$-on-SiC MOSFETs: Ulta-wide bandgap semiconductors based on $\\beta$-Ga$_2$O$_3$ offer the\npotential to achieve higher power switching performance, efficiency, and lower\nmanufacturing cost than today's wide bandgap power semiconductors. However, the\nmost critical challenge to the commercialization of Ga$_2$O$_3$ electronics is\noverheating, which impacts the device's performance and reliability. We\nfabricated a Ga$_2$O$_3$/4H-SiC composite wafer using a fusion-bonding method.\nA low temperature ($\\le$ 600 $^{\\circ}$C) epitaxy and device processing\napproach based on low-temperature (LT) metalorganic vapor phase epitaxy is\ndeveloped to grow a Ga$_2$O$_3$ epitaxial channel layer on the composite wafer\nand subsequently fabricate into Ga$_2$O$_3$ power MOSFETs. This LT approach is\nessential to preserve the structural integrity of the composite wafer. These\nLT-grown epitaxial Ga$_2$O$_3$ MOSFETs deliver high thermal performance (56%\nreduction in channel temperature), high voltage blocking capabilities up to\n2.45 kV, and power figures of merit of $\\sim$ 300 MW/cm$^2$, which is a record\nhigh for any heterogeneously integrated Ga$_2$O$_3$ devices reported to date.\nThis work is the first realization of multi-kilovolt homoepitaxial Ga$_2$O$_3$\npower MOSFETs fabricated on a composite substrate with high heat transfer\nperformance which delivers state-of-the-art power density values while running\nmuch cooler than those on native substrates. Thermal characterization and\nmodeling results reveal that a Ga$_2$O$_3$/diamond composite wafer with a\nreduced Ga$_2$O$_3$ thickness ($\\sim$ 1 $\\mu$m) and thinner bonding interlayer\n($<$ 10 nm) can reduce the device thermal impedance to a level lower than\ntoday's GaN-on-SiC power switches."
    },
    {
        "anchor": "Effects of temperature gradient on the interface microstructure and\n  diffusion of diffusion couples: phase-field simulation: The temporal interface microstructure and diffusion in the diffusion couples\nwith the mutual interactions of temperature gradient, concentration difference\nand initial aging time of the alloys were studied by phase-field simulation,\nthe diffusion couples are produced by the initial aged spinodal alloys with\ndifferent compositions. Temporal composition evolution and volume fraction of\nthe separated phase indicates the element diffusion direction through the\ninterface under the temperature gradient. The increased temperature gradient\ninduces a wide single-phase region at two sides of the interface. The uphill\ndiffusion proceeds through the interface, no matter the diffusion directions\nare up or down to the temperature gradient. For an alloy with short initial\naging time, phase transformation accompanying the interdiffusion results in the\nstraight interface with the single-phase regions at both sides. Comparing with\nthe temperature gradient, composition difference of diffusion couple and\ninitial aging time of the alloy show greater effect on the diffusion and\ninterface microstructure.",
        "positive": "Maser Threshold Characterization by Resonator Q-Factor Tuning: Whereas the laser is nowadays an ubiquitous technology, applications for its\nmicrowave analogue, the maser, remain highly specialized, despite the excellent\nlow-noise microwave amplification properties. The widespread application of\nmasers is typically limited by the need of cryogenic temperatures. The recent\nrealization of a continuous-wave room-temperature maser, using NV$^-$ centers\nin diamond, is a first step towards establishing the maser as a potential\nplatform for microwave research and development, yet its design is far from\noptimal. Here, we design and construct an optimized setup able to characterize\nthe operating space of a maser using NV$^-$ centers. We focus on the interplay\nof two key parameters for emission of microwave photons: the quality factor of\nthe microwave resonator and the degree of spin level-inversion. We characterize\nthe performance of the maser as a function of these two parameters, identifying\nthe parameter space of operation and highlighting the requirements for maximal\ncontinuous microwave emission."
    },
    {
        "anchor": "Anomalous magnetotransport properties of high-quality single crystals of\n  Weyl semimetal WTe2: Sign change of Hall resistivity: We report on a systematic study of Hall effect using high quality single\ncrystals of type-II Weyl semimetal WTe2 with the applied magnetic field B//c.\nThe residual resistivity ratio of 1330 and the large magnetoresistance of\n1.5\\times10^6 % in 9 T at 2 K, being in the highest class in the literature,\nattest to their high quality. Based on a simple two-band model, the densities\n(n_e and n_h) and mobilities (\\mu_e and \\mu_h) for electron and hole carriers\nhave been uniquely determined combining both Hall- and electrical-resistivity\ndata. The difference between ne and nh is ~1% at 2 K, indicating that the\nsystem is in an almost compensated condition. The negative Hall resistivity\ngrowing rapidly below ~20 K is due to a rapidly increasing \\mu_h/\\mu_e\napproaching one. Below 3 K in a low field region, we found the Hall resistivity\nbecomes positive, reflecting that \\mu_h/\\mu_e finally exceeds one in this\nregion. These anomalous behaviors of the carrier densities and mobilities might\nbe associated with the existence of a Lifshitz transition and/or the spin\ntexture on the Fermi surface.",
        "positive": "Direct measurement of the magnetic field effects on carrier mobilities\n  and recombination in tri-(8-hydroxyquinoline)-aluminum based light-emitting\n  diodes: The magnetic field effects on the carrier mobilities and recombination in\ntri-(8-hydroxyquinoline)-aluminum (Alq3) based light-emitting diodes have been\nmeasured by the method of transient electroluminescence. It is confirmed that\nthe magnetic field has no effect on the electron and hole mobilities in Alq3\nlayers and can decrease the electron-hole recombination coefficient. The\nresults imply that the dominant mechanism for the magnetic field effects in\nAlq3 based light-emitting diodes is the interconversion between singlet e-h\npairs and triplet e-h pairs modulated by the magnetic field when the driving\nvoltage is larger than the onset voltage of the electroluminescence."
    },
    {
        "anchor": "From regular lattice to scale free network - yet another algorithm: The Watts-Strogatz algorithm transferring a regular lattice to the small\nworld network is modified by introducing preferential rewiring constrained by\nconnectivity demand. The probability to link to/ unlink form a node is\ndependent on a vertex degree and adjusted by some threshold. For each threshold\nvalue there exists a probability at which the resulting stationary network has\ndegree distribution with power-law decay in large interval of degrees.",
        "positive": "Density functional study of elastic and vibrational properties of the\n  Heusler-type alloys Fe$_2$VAl and Fe$_2$VGa: The structural and elastic properties as well as phonon-dispersion relations\nof the Heusler-type alloys Fe$_2$VAl and Fe$_2$VGa are computed using\ndensity-functional and density-functional perturbation theory within the\ngeneralized-gradient approximation. The calculated equilibrium lattice\nconstants agree well with the experimental values. The elastic constants of\nFe$_2$VAl and Fe$_2$VGa are predicted for the first time. From the elastic\nconstants the shear modulus, Young's modulus, Poisson's ratio, sound velocities\nand Debye temperatures are obtained. By analyzing the ratio between the bulk\nand shear modulii, we conclude that both Fe$_2$VAl and Fe$_2$VGa are brittle in\nnature. The computed phonon-dispersion relation shows that both compounds are\ndynamically stable in the L1$_2$ structure without any imaginary phonon\nfrequencies. The isomer shifts of Fe in the two compounds are discussed in\nterms of the Fe s partial density of states, which reveal larger ionicity/less\nhybridization in Fe$_2$VGa than in Fe$_2$VAl. For the same reason the Cauchy\npressure is negative in Fe$_2$VAl but positive in Fe$_2$VGa"
    },
    {
        "anchor": "Spectroscopic signature of obstructed surface states in SrIn$_2$P$_2$: The century-long development of surface sciences has witnessed the\ndiscoveries of a variety of quantum states. In the recently proposed\n\"obstructed atomic insulators\", insulators with symmetric charges pinned at\nvirtual sites where no real atoms reside, the cleavage through these sites\ncould lead to a set of obstructed surface states with partial occupation. Here,\nutilizing scanning tunneling microscopy, angle-resolved photoemission\nspectroscopy and first-principles calculations, we observe spectroscopic\nsignature of obstructed surface states in SrIn$_2$P$_2$. We find a pair of\nsurface states originated from the pristine obstructed surface states split by\na unique surface reconstruction. The upper branch is marked with a striking\ndifferential conductance peak followed by negative differential conductance,\nsignaling its localized nature, while the lower branch is found to be highly\ndispersive. This pair of surface states is in consistency with our\ncalculational results. Our finding not only demonstrates a surface quantum\nstate induced by a new type of bulk-boundary correspondence, but also provides\na platform for exploring efficient catalysts and related surface engineering.",
        "positive": "Atomistic simulations of surface reactions in ultra-high-temperature\n  ceramics: O2, H2O and CO adsorption and dissociation on ZrB2 (0001) surfaces: Understanding surface reactivity is crucial in many fields, going from\nheterogeneous catalysis to materials oxidation and corrosion. In order to\ndecipher the surface reactions of ZrB2 exposed to the harsh environment of\naerospace components, the chemical activity of both Zr- and B-surfaces is\npredicted and compared by using density functional theory and nudged elastic\nband methods. In particular the adsorption, dissociation and diffusion of O2,\nCO and H2O are extensively examined through the calculation of surface\nadsorption energies and reaction pathways. We find the dissociative adsorption\nof O2 dominating the reactivity of ZrB2 surfaces, while the dissociation of H2O\nand CO is weakly active on Zr-surfaces, and even less activated on B-terminated\nones. Importantly, we discover that the reaction of O2 and H2O can trigger\nstrong surface reconstruction at B-surfaces. Our work thus provides significant\ninsights into the diverse adsorption and reaction mechanisms of ZrB2 surfaces."
    },
    {
        "anchor": "Predicting orientation-dependent plastic susceptibility from static\n  structure in amorphous solids via deep learning: It has been a long-standing materials science challenge to establish\nstructure-property relations in amorphous solids. Here we introduce a\nrotation-variant local structure representation that enables different\npredictions for different loading orientations, which is found essential for\nhigh-fidelity prediction of the propensity for stress-driven shear\ntransformations. This novel structure representation, when combined with\nconvolutional neural network (CNN), a powerful deep learning algorithm, leads\nto unprecedented accuracy for identifying atoms with high propensity for shear\ntransformations (i.e., plastic susceptibility), solely from the static\nstructure - the spatial atomic positions - in both two- and three-dimensional\nmodel glasses. The data-driven models trained on samples at one composition and\na given processing history are found transferrable to glass samples with\ndifferent processing histories or at different compositions in the same alloy\nsystem. Our analysis of the new structure representation also provides valuable\ninsight into key atomic packing features that influence the local mechanical\nresponse and its anisotropy in glasses.",
        "positive": "Dilatancy of Shear Transformations in a Colloidal Glass: Shear transformations, as fundamental rearrangement events operating in local\nregions, hold the key of plastic flow of amorphous solids. Despite their\nimportance, the dynamic features of shear transformations are far from clear.\nHere, we use a colloidal glass under shear as the prototype to directly observe\nthe shear transformation events in real space. By tracing the colloidal\nparticle rearrangements, we quantitatively determine two basic properties of\nshear transformations: local shear strain and dilatation (or free volume). It\nis revealed that the local free volume undergoes a significantly temporary\nincrease prior to shear transformations, eventually leading to a jump of local\nshear strain. We clearly demonstrate that shear transformations have no memory\nof the initial free volume of local regions. Instead, their emergence strongly\ndepends on the dilatancy ability of these regions, i.e., the dynamic creation\nof free volume. More specifically, the particles processing the high dilatancy\nability directly participate in subsequent shear transformations. These results\nexperimentally support the Argon's statement about the dilatancy nature of\nshear transformations, and also shed insight into the structural origin of\namorphous plasticity."
    },
    {
        "anchor": "Elastic fields of stationary and moving dislocations in three\n  dimensional finite samples: Integral expressions are determined for the elastic displacement and stress\nfields due to stationary or moving dislocation loops in three dimensional, not\nnecessarily isotropic, finite samples. A line integral representation is found\nfor the stress field, thus satisfying the expectation that stresses should\ndepend on the location of the dislocation loop, but not on the location of\nsurfaces bounded by such loops that are devoid of physical significance. In the\nstationary case the line integral representation involves a ``vector\npotential'' that depends on the specific geometry of the sample, through its\nGreen's function: a specific combination of derivatives of the elastic stress\nproduced by the Green's function appropriate for the sample is divergenceless,\nso it is the curl of this ``vector potential''. This ``vector potential'' is\nexplicitely determined for an isotropic half space and for a thin plate.\nEarlier specific results in these geometries are recovered as special cases. In\nthe non stationary case a line integral representation can be obtained for the\ntime derivative of the stress field. This, combined with the static result,\nassures a line integral representation for the time dependent stress field.",
        "positive": "Band structure model of magnetic coupling in semiconductors: We present a unified band structure model to explain magnetic ordering in\nMn-doped semiconductors. This model is based on the $p$-$d$ and $d$-$d$ level\nrepulsions between the Mn ions and host elements and can successfully explain\nmagnetic ordering observed in all Mn doped II-VI and III-V semiconductors such\nas CdTe, GaAs, ZnO, and GaN. This model, therefore, provides a simple guideline\nfor future band structure engineering of magnetic semiconductors."
    },
    {
        "anchor": "Electron-Energy-Loss Spectra of Free-Standing Silicene: Silicene is becoming one of the most important two-dimensional materials. In\nthis work, EEL Spectra were calculated for alfa-silicene (flat), and\nbeta-silicene (low-buckled, and theoretically the most stable). Band structures\nwere determined using the semi-empirical Tight-Binding Method considering\nsecond nearest neighbors, sp3 model, Harrison's rule, and Slater-Koster\nparameterization. The dielectric function was calculated within the Random\nPhase Approximation and a space discretization scheme. We found that, compared\nto bulk Si, additional resonances appear which are red-shifted. Buckling gives\nrise to a richer structure at low energy.",
        "positive": "Non-neglectable entropy effect on sintering of supported nanoparticles: Sintering refers to particle coalescence by heat, which has been known as a\nthermal phenomenon involving all aspects of natural science for centuries. It\nis particularly important in heterogeneous catalysis because normally sintering\nresults in deactivation of the catalysts. In previous studies, the enthalpy\ncontribution was considered to be dominant in sintering and the entropy effect\nis generally considered neglectable. However, we unambiguously demonstrate in\nthis work that entropy could prevail over the enthalpy contribution to dominate\nthe sintering behavior of supported nanoparticles (NPs) by designed experiments\nand improved theoretical framework. Using in situ Cs-corrected environmental\nscanning transmission electron microscopy and synchrotron-based ambient\npressure X-ray photoelectron spectroscopy, we observe the unprecedent\nentropy-driven phenomenon that supported NPs reversibly redisperse upon heating\nand sinter upon cooling in three systems (Pd-CeO2, Cu-TiO2, Ag-TiO2). We\nquantitatively show that the configurational entropy of highly dispersed\nad-atoms is large enough to reverse their sintering tendency at the elevated\ntemperature. This work reshapes the basic understanding of sintering at the\nnanoscale and opens the door for various de-novo designs of thermodynamically\nstable nanocatalysts."
    },
    {
        "anchor": "Effect of local anisotropy on fatigue crack initiation in a coarse\n  grained nickel-base superalloy: In the present work, theoretical approaches, based on grain orientation\ndependent Young's modulus and Schmid factor are used to describe the influence\nof local grain orientation on crack initiation behaviour of the coarse grained\nnickel base superalloy Ren\\'e80. Especially for strongly anisotropic crystal\nstructures with large grain size, such as the investigated material, the local\nelastic properties must be taken into account for assessment of fatigue crack\ninitiation. With an extension of Schmid's law, the resulting shear stress\namplitude, which triggers local cyclic plastic deformation, can be calculated\ndepending on local Young's modulus and Schmid factor. A Monte Carlo simulation\nwith 100,000 samples shows how random grain orientation affects these\nparameters. Furthermore, the product of Young's modulus and Schmid factor\n(called $E\\cdot m$) is used as a parameter to determine how grain orientation\ninfluences resulting shear stress amplitude for given total strain amplitude.\nIn addition to the theoretical work using that approach, this model is also\nvalidated using isothermal LCF experiments by determining local grain\norientation influence on the crack initiation site using SEM-EBSD analyses.",
        "positive": "Investigation of the effect of the grain sizes on the dynamic strength\n  of the fine-grained alumina ceramics obtained by Spark Plasma Sintering: The results of dynamic strength tests of the alumina ceramics with various\ngrain sizes are presented. The ceramics were obtained by Spark Plasma Sintering\n(SPS) of industrial submicron and fine Al2O3 powders. The heating up was\nperformed with the rate of 10 oC/min; the grain sizes in the ceramics was\ncontrolled by varying the SPS temperature and the heating rate as well as by\nvarying the initial sizes of the Al2O3 particles in the powders. The ceramics\nhad a high density (over 98%) and a uniform fine-grained microstructure (the\nmean grain sizes varied from 0.8 to 13.4 mkm). The dynamic compressing tests\nwere carried out by modified Kolsky method with using split Hopkinson pressure\nbar. The tests were performed at room temperature using a 20-mm PG-20 gas gun\nwith the strain rate of ~10^3 s-1. The dependence of the dynamic ultimate\nstrength of alumina on the grain size was found for the first time to have a\nnon-monotonous character (with a maximum). The maximum value of the dynamic\nultimate compression strength (SY = 1060 MPa) was provided at the mean grain\nsize of ~2.9-3 mkm. The reduction of SY for alumina in the range of submicron\ngrain sizes was shown to originate from the reduction of the relative density\nof the ceramics sintered at lower SPS temperatures."
    },
    {
        "anchor": "Ab-Initio Study on the Hard Magnetic Properties of MnBi: We have studied the hard magnetic properties of the low-temperature phase of\nMnBi with first principle calculations based on the density functional theory.\nThe calculations have been carried out on two distinct unit cell configurations\nMnBi and BiMn with the element in the unit cell origin named first. Our results\nshow that these configurations are not equivalent and that MnBi describes the\nsystem better near T = 0K and the BiMn configuration describes the system\nbetter for T > 300K. The magnetic moments of both configurations agree well\nwith experimental measurements considering both spin and orbital contributions.\nAt high temperatures the magneto-crystalline anisotropy energy increases with\nincreasing unit cell volume and reaches a maximum of 2:3MJ=m3 and a c=a ratio\nof 1:375.",
        "positive": "Morphogenesis and propagation of complex cracks induced by thermal\n  shocks: We study the genesis and the selective propagation of complex crack networks\ninduced by thermal shock or drying of brittle materials. We use a quasi-static\ngradient damage model to perform large scale numerical simulations showing that\nthe propagation of fully developed cracks follows Griffith criterion and\ndepends only on the fracture toughness, while crack morphogenesis is driven by\nthe material's internal length. Our numerical simulations feature networks of\nparallel cracks and selective arrest in two dimensions and hexagonal columnar\njoints in three dimensions, without any hypotheses on cracks geometry and are\nin good agreement with available experimental results."
    },
    {
        "anchor": "A curved line search algorithm for atomic structure relaxation: Ab initio atomic relaxations often take large numbers of steps and long times\nto converge. An atomic relaxation method based on on-the-flight force learning\nand a corresponding new curved line minimization algorithm is presented to\ndramatically accelerate this process. Results for metal clusters demonstrate\nthe significant speedup of this method compared with conventional\nconjugate-gradient method.",
        "positive": "Spin Amplification for Magnetic Sensors Employing Crystal Defects: Recently there have been several theoretical and experimental studies of the\nprospects for magnetic field sensors based on crystal defects, especially\nnitrogen vacancy (NV) centres in diamond. Such systems could potentially be\nincorporated into an AFM-like apparatus in order to map the magnetic properties\nof a surface at the single spin level. In this Letter we propose an augmented\nsensor consisting of an NV centre for readout and an `amplifier' spin system\nthat directly senses the local magnetic field. Our calculations show that this\nhybrid structure has the potential to detect magnetic moments with a\nsensitivity and spatial resolution far beyond that of a simple NV centre, and\nindeed this may be the physical limit for sensors of this class."
    },
    {
        "anchor": "Ab-initio based models for temperature-dependent magneto-chemical\n  interplay in bcc Fe-Mn alloys: Body-centered cubic (bcc) Fe-Mn systems are known to exhibit a complex and\natypical magnetic behaviour from both experiments and 0 K electronic-structure\ncalculations, which is due to the half-filled 3d-band of Mn. We propose\neffective interaction models for these alloys, which contain both atomic spin\nand chemical variables. They were parameterized on a set of key density\nfunctional theory (DFT) data, with the inclusion of non-collinear magnetic\nconfigurations being indispensable. Two distinct approaches, namely a\nknowledge-driven and a machine-learning approach have been employed for the\nfitting. Employing these models in atomic Monte Carlo simulations enables the\nprediction of magnetic and thermodynamic properties of the Fe-Mn alloys, and\ntheir coupling, as functions of temperature. This includes the decrease of\nCurie temperature with increasing Mn concentration, the temperature evolution\nof the mixing enthalpy and its correlation with the alloy magnetization. Also,\ngoing beyond the defect-free systems, we determined the binding free energy\nbetween a vacancy and a Mn atom, which is a key parameter controlling the\natomic transport in Fe-Mn alloys.",
        "positive": "Ab initio vacancy formation energies and kinetics at metal surfaces\n  under high electric field: Recording field ion microscope images under field evaporating conditions and\nsubsequently reconstructing the underlying atomic configuration, called\nthree-dimensional field ion microscopy (3D-FIM) is one of the few techniques\ncapable of resolving crystalline defects at an atomic scale. However, the\nquantification of the observed vacancies and their origins are still a matter\nof debate. It was suggested that high electric fields (1-5 V/\\r{A}) used in\n3D-FIM could introduce artefact vacancies. To investigate such effects, we used\ndensity functional theory (DFT) simulations. Stepped Ni and Pt surfaces with\nkinks were modelled in the repeated slab approach with a (971) surface\norientation. An electrostatic field of up to 4 V/\\r{A} was introduced on one\nside of the slab using the generalized dipole correction. Contrary to what was\nproposed, we show that the formation of vacancies on the electrified metal\nsurface is more difficult compared to a field-free case. We also find that the\nelectric field can introduce kinetic barriers to a potential\nvacancy-annihilation mechanism. We rationalize these findings by comparing to\ninsights from field evaporation models."
    },
    {
        "anchor": "Radiation efficiency of heavily doped bulk n-InP semiconductor: Recombination of minority carriers in heavily doped n-InP wafers has been\ninvestigated using spectral and time-resolved photoluminescence at different\ntemperatures. Studies of the transmitted luminescence were enabled by the\npartial transparency of the samples due to the Moss-Burstein effect. Temporal\nevolution of the transmitted luminescence shows virtually no effect of surface\nrecombination but is strongly influenced by photon recycling. Temperature\ndependence of the decay time suggests Auger recombination as the dominant\nnon-radiative process at room temperature. Radiative quantum efficiency has\nbeen evaluated at different doping levels and at 2x1018 cm-3 it is found to be\nas high as 97%, which makes n-InP suitable for scintillator application.",
        "positive": "Observation of inhomogeneous domain nucleation in epitaxial Pb(Zr,Ti)O3\n  capacitors: We investigated domain nucleation process in epitaxial Pb(Zr,Ti)O3 capacitors\nunder a modified piezoresponse force microscope. We obtained domain evolution\nimages during polarization switching process and observed that domain\nnucleation occurs at particular sites. This inhomogeneous nucleation process\nshould play an important role in an early stage of switching and under a high\nelectric field. We found that the number of nuclei is linearly proportional to\nlog(switching time), suggesting a broad distribution of activation energies for\nnucleation. The nucleation sites for a positive bias differ from those for a\nnegative bias, indicating that most nucleation sites are located at\nferroelectric/electrode interfaces."
    },
    {
        "anchor": "Electronic states and molecular dynamics of single-component molecular\n  conductors [M(tmdt)$_2$] (M=Ni, Pt) studied by $^{13}$C and $^1$H NMR: The molecular conductors [M(tmdt)$_2$] (M=Ni, Pt) consisting of single\nmolecular species are investigated with $^{13}$C NMR and $^1$H NMR. The\ntemperature dependences of $^{13}$C NMR shift and relaxation rate provide\nmicroscopic evidences for the metallic nature with appreciable electron\ncorrelations. Both compounds exhibit an anomalous frequency-dependent\nenhancement in $^1$H nuclear spin-lattice relaxation rate in a wide temperature\nrange. These observations signify the presence of extraordinary molecular\nmotions with low energy excitations.",
        "positive": "Unravelling Dzyaloshinskii-Moriya interaction and chiral nature of\n  Graphene/Cobalt interface: A major challenge for future spintronics is to develop suitable spin\ntransport channels with long spin lifetime and propagation length. Graphene can\nmeet these requirements, even at room temperature. On the other side, taking\nadvantage of the fast motion of chiral textures, i.e., N\\'eel-type domain walls\nand magnetic skyrmions, can satisfy the demands for high-density data storage,\nlow power consumption and high processing speed. We have engineered epitaxial\nstructures where an epitaxial ferromagnetic Co layer is sandwiched between an\nepitaxial Pt(111) buffer grown in turn onto MgO(111) substrates and a graphene\nlayer. We provide evidence of a graphene-induced enhancement of the\nperpendicular magnetic anisotropy up to 4 nm thick Co films, and of the\nexistence of chiral left-handed N\\'eel-type domain walls stabilized by the\neffective Dzyaloshinskii-Moriya interaction (DMI) in the stack. The experiments\nshow evidence of a sizeable DMI at the gr/Co interface, which is described in\nterms of a conduction electron mediated Rashba-DMI mechanism and points\nopposite to the Spin Orbit Coupling-induced DMI at the Co/Pt interface. In\naddition, the presence of graphene results in: i) a surfactant action for the\nCo growth, producing an intercalated, flat, highly perfect fcc film,\npseudomorphic with Pt and ii) an efficient protection from oxidation. The\nmagnetic chiral texture is stable at room temperature and grown on insulating\nsubstrate. Our findings open new routes to control chiral spin structures using\ninterfacial engineering in graphene-based systems for future spin-orbitronics\ndevices fully integrated on oxide substrates."
    },
    {
        "anchor": "Gate-tuning of graphene plasmons revealed by infrared nano-imaging: Surface plasmons are collective oscillations of electrons in metals or\nsemiconductors enabling confinement and control of electromagnetic energy at\nsubwavelength scales. Rapid progress in plasmonics has largely relied on\nadvances in device nano-fabrication, whereas less attention has been paid to\nthe tunable properties of plasmonic media. One such medium-graphene-is amenable\nto convenient tuning of its electronic and optical properties with gate\nvoltage. Through infrared nano-imaging we explicitly show that common\ngraphene/SiO2/Si back-gated structures support propagating surface plasmons.\nThe wavelength of graphene plasmons is of the order of 200 nm at\ntechnologically relevant infrared frequencies, and they can propagate several\ntimes this distance. We have succeeded in altering both the amplitude and\nwavelength of these plasmons by gate voltage. We investigated losses in\ngraphene using plasmon interferometry: by exploring real space profiles of\nplasmon standing waves formed between the tip of our nano-probe and edges of\nthe samples. Plasmon dissipation quantified through this analysis is linked to\nthe exotic electrodynamics of graphene. Standard plasmonic figures of merits of\nour tunable graphene devices surpass that of common metal-based structures.",
        "positive": "High Field Magneto-Conductivity Analysis of Bi2Se3 Single Crystal: We report the high field (up to 14Tesla) magneto-conductivity analysis of\nBi2Se3 topological insulator grown via the self flux method. The detailed\nexperimental investigations including crystal growth as well as the electrical,\nthermal and spectroscopic characterizations of the resultant Bi2Se3 single\ncrystal are already reported by some of us. The current letter deals with high\nfield magneto-conductivity analysis in terms of Hikami Larkin Nagaoka (HLN)\nmodel, which revealed that the electronic conduction is dominated by both\nsurface states driven weak anti localization (WAL), as well the bulk WL (weak\nlocalization) states. Further, by applying the HLN equation we have extracted\nthe fitting parameters i.e., phase coherence length and the pre-factor. The HLN\nequation exhibited values of [pre factor close to -1.0, indicating both WAL and\nWL contributions. On the other hand, the extracted phase coherence length is\nseen to decrease from 11.125 nm to 5.576 nm as the temperature is increased\nfrom 5K to 200K respectively. Summarily, the short letter discusses primarily\nthe temperature dependent magneto-conductivity analysis of pristine Bi2Se3\nsingle crystal by the HLN model."
    },
    {
        "anchor": "A first-principles study of helium storage in oxides and at oxide--iron\n  interfaces: Density-functional theory calculations based on conventional as well as\nhybrid exchange-correlation functionals have been carried out to study the\nproperties of helium in various oxides (Al2O3, TiO2, Y2O3, YAP, YAG, YAM, MgO,\nCaO, BaO, SrO) as well as at oxide-iron interfaces. Helium interstitials in\nbulk oxides are shown to be energetically more favorable than substitutional\nhelium, yet helium binds to existing vacancies. The solubility of He in oxides\nis systematically higher than in iron and scales with the free volume at the\ninterstitial site nearly independently of the chemical composition of the\noxide. In most oxides He migration is significantly slower and He--He binding\nis much weaker than in iron. To quantify the solubility of helium at oxide-iron\ninterfaces two prototypical systems are considered (Fe|MgO, Fe|FeO|MgO). In\nboth cases the He solubility is markedly enhanced in the interface compared to\neither of the bulk phases. The results of the calculations allow to construct a\nschematic energy landscape for He interstitials in iron. The implications of\nthese results are discussed in the context of helium sequestration in oxide\ndispersion strengthened steels, including the effects of interfaces and lattice\nstrain.",
        "positive": "Ni Schottky barrier on heavily doped phosphorous implanted 4H-SiC: The electrical behavior of Ni Schottky barrier formed onto heavily doped\n(ND>1019 cm-3) n-type phosphorous implanted silicon carbide (4H-SiC) was\ninvestigated, with a focus on the current transport mechanisms in both forward\nand reverse bias. The forward current-voltage characterization of Schottky\ndiodes showed that the predominant current transport is a thermionic-field\nemission mechanism. On the other hand, the reverse bias characteristics could\nnot be described by a unique mechanism. In fact, under moderate reverse bias,\nimplantation-induced damage is responsible for the temperature increase of the\nleakage current, while a pure field emission mechanism is approached with bias\nincreasing. The potential application of metal/4H-SiC contacts on heavily doped\nlayers in real devices are discussed."
    },
    {
        "anchor": "The third dimension of ferroelectric domain walls: Ferroelectric domain walls are quasi-2D systems that show great promise for\nthe development of non-volatile memory, memristor technology and electronic\ncomponents with ultra-small feature size. Electric fields, for example, can\nchange the domain wall orientation relative to the spontaneous polarization and\nswitch between resistive and conductive states, controlling the electrical\ncurrent. Being embedded in a 3D material, however, the domain walls are not\nperfectly flat and can form networks, which leads to complex physical\nstructures. We demonstrate the importance of the nanoscale structure for the\nemergent transport properties, studying electronic conduction in the 3D network\nof neutral and charged domain walls in ErMnO$_3$. By combining tomographic\nmicroscopy techniques and finite element modelling, we clarify the contribution\nof domain walls within the bulk and show the significance of curvature effects\nfor the local conduction down to the nanoscale. The findings provide insights\ninto the propagation of electrical currents in domain wall networks, reveal\nadditional degrees of freedom for their control, and provide quantitative\nguidelines for the design of domain wall based technology.",
        "positive": "Descriptor for slip-induced crack-blunting in refractory ceramics: Understanding the competition between brittleness and plasticity in\nrefractory ceramics is of importance for aiding design of hard materials with\nenhanced fracture resistance. Inspired by experimental observations of crack\nshielding due to dislocation activity in TiN ceramics [Int J Plast 27 (2011)\n739], we carry out comprehensive atomistic investigations to identify\nmechanisms responsible for brittleness and slip-induced plasticity in Ti-N\nsystems. First, we validate a semi-empirical interatomic potential against\ndensity-functional theory results of Griffith and Rice stress intensities for\ncleavage (KIc) and dislocation emission (KIe) as well as ab initio molecular\ndynamics mechanical-testing simulations of pristine and defective TiN lattices\nat temperatures between 300 and 1200 K. The calculated KIc and KIe values\nindicate intrinsic brittleness, as KIc<<KIe. However, KI-controlled molecular\nstatics simulations - which reliably forecast macroscale mechanical properties\nthrough nanoscale modelling - reveal that slip-plasticity can be promoted by a\nreduced sharpness of the crack and/or the presence of anion vacancies.\nClassical molecular dynamics simulations of notched Ti-N supercell models\nsubject to tension provide a qualitative understanding of the competition\nbetween brittleness and plasticity at finite temperatures. Although crack\ngrowth occurs in most cases, a sufficiently rapid accumulation of shear stress\nat the notch tip may postpone or prevent fracture via nucleation and emission\nof dislocations. Furthermore, we show that the probability to observe\nslip-induced plasticity leading to crack-blunting in flawed Ti-N lattices\ncorrelates with the ideal tensile/shear strength ratio (Iplast) of pristine\nTi-N crystals. We propose that the Iplast descriptor should be considered for\nranking the ability of ceramics to blunt cracks via dislocation-mediated\nplasticity at finite temperatures."
    },
    {
        "anchor": "Changes in the electronic structure and properties of graphene induced\n  by molecular charge-transfer: Interaction with electron donor and acceptor molecules such as aniline and\nnitrobenzene brings about marked changes in the Raman spectrum and the\nelectronic structure of graphene, prepared by the exfoliation of graphitic\noxide.",
        "positive": "Engineering Transport in Manganites by Tuning Local Non-Stoichiometry in\n  Grain Boundaries: Interface-dominated materials such as nanocrystalline thin films have emerged\nas an enthralling class of materials able to engineer functional properties of\ntransition metal oxides widely used in energy and information technologies. In\nparticular, it has been proved that strain-induced defects in grain boundaries\nof manganites deeply impact their functional properties by boosting their\noxygen mass transport while abating their electronic and magnetic order. In\nthis work, the origin of these dramatic changes is correlated for the first\ntime with strong modifications of the anionic and cationic composition in the\nvicinity of strained grain boundary regions. We are also able to alter the\ngrain boundary composition by tuning the overall cationic content in the films,\nwhich represents a new and powerful tool, beyond the classical space charge\nlayer effect, for engineering electronic and mass transport properties of metal\noxide thin films useful for a collection of relevant solid state devices."
    },
    {
        "anchor": "Simultaneous dynamic characterization of charge and structural motion\n  during ferroelectric switching: Monitoring structural changes in ferroelectric thin films during electric\nfield-induced polarization switching is important for a full microscopic\nunderstanding of the coupled motion of charges, atoms and domain walls. We\ncombine standard ferroelectric test-cycles with time-resolved x-ray diffraction\nto investigate the response of a nanoscale ferroelectric oxide capacitor upon\ncharging, discharging and switching. Piezoelectric strain develops during the\nelectronic RC time constant and additionally during structural domain-wall\ncreep. The complex atomic motion during ferroelectric polarization reversal\nstarts with a negative piezoelectric response to the charge flow triggered by\nvoltage pulses. Incomplete screening limits the compressive strain. The\npiezoelectric modulation of the unit cell tweaks the energy barrier between the\ntwo polarization states. Domain wall motion is evidenced by a broadening of the\nin-plane components of Bragg reflections. Such simultaneous measurements on a\nworking device elucidate and visualize the complex interplay of charge flow and\nstructural motion and challenges theoretical modelling.",
        "positive": "Exploring Low Internal Reorganization Energies for Silicene Nanoclusters: High-performance materials rely on small reorganization energies to\nfacilitate both charge separation and charge transport. Here, we performed DFT\ncalculations to predict small reorganization energies of rectangular silicene\nnanoclusters with hydrogen-passivated edges denoted by H-SiNC. We observe that\nacross all geometries, H-SiNCs feature large electron affinities and highly\nstabilized anionic states, indicating their potential as n-type materials. Our\nfindings suggest that fine-tuning the size of H-SiNCs along the zigzag and\narmchair directions may permit the design of novel n-type electronic materials\nand spinctronics devices that incorporate both high electron affinities and\nvery low internal reorganization energies."
    },
    {
        "anchor": "Phase domain boundary motion and memristance in gradient-doped FeRh\n  nanopillars induced by spin injection: The B2-ordered alloy FeRh shows a metamagnetic phase transition, transforming\nfrom antiferromagnetic (AF) to ferromagnetic (FM) order at a temperature\n$T_\\mathrm{t} \\sim 380 $~K in bulk. As well as temperature, the phase\ntransition can be triggered by many means such as strain, chemical doping, or\nmagnetic or electric fields. Its first-order nature means that phase\ncoexistence is possible. Here we show that a phase boundary in a 300~nm\ndiameter nanopillar, controlled by a doping gradient during film growth, is\nmoved by an electrical current in the direction of electron flow. We attribute\nthis to spin injection from one magnetically ordered phase region into the\nother driving the phase transition in a region just next to the phase boundary.\nThe associated change in resistance of the nanopillar shows memristive\nproperties, suggesting potential applications as memory cells or artificial\nsynapses in neuromorphic computing schemes.",
        "positive": "Pressure dependence of Tc in the MgB2 superconductor as probed by\n  resistivity measurements: High-pressure resistivity experiments were performed on the recently\ndiscovered superconductor, MgB2. Tc decreases quasi-linearly with applied\npressure to 1.4 GPa at a rate of -2.0(1) K/GPa, which is somewhat larger than\nthat derived from recently-reported ac susceptibility measurements. The\nreduction of Tc is consistent with the BCS picture, in a similar way to the\nC60-based superconductors. Taking into account the pressure dependence of the\nunit cell volume, V, the volume coefficient of Tc, d(lnTc)/dV is significantly\nlarge."
    },
    {
        "anchor": "Off-axis electron holography and microstructure of Ba0.5Sr0.5TiO3 thin\n  film grown on LaAlO3: Epitaxial Ba0.5Sr0.5TiO3 thin films grown on the (001) LaAlO3 substrates with\nthe ferroelectric transition of about 250K have been investigated by TEM and\noff-axis electron holography. Cross-sectional TEM observations show that the\n350nm-thick Ba0.5Sr0.5TiO3 film has a sharp interface with notable misfit\ndislocations. Off-axis electron holographic measurements reveal that, at low\ntemperatures, the ferroelectric polarization results in systematic\naccumulations of negative charges on the interface and positive charges on the\nfilm surface, and, at room temperature, certain charges could only accumulate\nat the interfacial dislocations and other defective areas.",
        "positive": "Insights into the Hierarchical Structure of Spider Dragline Silk Fibers:\n  Evidence for Fractal Clustering of $\u03b2$-Sheet Nano-Crystallites: Spider dragline silk is one of the toughest materials known and understanding\nthe hierarchical structure is a critical component in the efforts to connect\nstructure to function. In this paper, we take the first step in elucidating the\nhierarchical fractal structure of $\\beta$-sheet nano-crystallites, which form a\nrobust self-similar network exhibiting an non-linear mechanical property. A\ncombined small angle X-ray scattering (SAXS) and wide-angle X-ray scattering\n(WAXS) study of the nano-crystalline component in dragline silk fibers from\nseveral species of spiders including, Latrodectus hesperus, Nephila clavipes,\nArgiope aurantia and Araneus gemmoides is presented. SAXS structure factors\nexhibit a `lamellar peak' in the q-range from 0.60 to 0.82 nm$^{-1}$ for\nvarious spider dragline silk fibers, indicating the presence of strong\nnano-crystal ordering on the $>$10 nm length-scale. The stochastically\nreconstructed electron density maps indicate that the $\\beta$-sheet crystals\nare hierarchically structured as mass fractals and that nano-crystals tend to\nform 10 to 50 nm sized clusters with long-range crystalline ordering. This\nnano-crystal ordering along the fiber axis also helps to explain the difference\nbetween axial and radial sound velocities recently measured by Brillouin\nspectroscopy."
    },
    {
        "anchor": "Enhanced Domain Wall Motion in the Spin Valve Nanowires: According to the recent experiment by the Fert group, the velocity of domain\nwall motion in the spin valve ferromagnetic nanowires was almost doubly\nenhanced compared to the old value. In this work, we propose an additional\ntorque model, arising from the interlayer exchange interaction, which can\nenhance or suppress the domain wall velocity depending on the sign of the\nexchange constant or the wall motion direction relative to the magnetization\norientation of the fixed layer.",
        "positive": "Electron-Electron Interactions on the Edge States of Graphene: A Many\n  Body Configuration Interaction Study: We have studied zigzag and armchair graphene nano ribbons (GNRs), described\nby the Hubbard Hamiltonian using quantum many body configuration interaction\nmethods. Due to finite termination, we find that the bipartite nature of the\ngraphene lattice gets destroyed at the edges making the ground state of the\nzigzag GNRs a high spin state, whereas the ground state of the armchair GNRs\nremains a singlet. Our calculations of charge and spin densities suggest that,\nalthough the electron density prefers to accumulate on the edges, instead of\nspin polarization, the up and down spins prefer to mix throughout the GNR\nlattice. While the many body charge gap results in insulating behavior for both\nkinds of GNRs, the conduction upon application of electric field is still\npossible through the edge channels because of their high electron density.\nAnalysis of optical states suggest differences in quantum efficiency of\nluminescence for zigzag and armchair GNRs, which can be probed by simple\nexperiments."
    },
    {
        "anchor": "Influence of anisotropy, tilt and pairing of Weyl nodes: The Weyl\n  semimetals TaAs, TaP, NbAs and NbP: By means of $ab \\ initio$ band structure methods and model Hamiltonians we\ninvestigate the electronic, spin and topological properties of four\nmonopnictides crystallizing in body centered tetragonal structure. We show that\nthe Weyl bands around a Weyl point W1 or W2 possess a strong anisotropy and\ntilt of the accompanying Dirac cones. These effects are larger for W2 nodes\nthan for W1 ones. The node tilts and positions in energy space significantly\ninfluence the density of states of single-particle Weyl excitations. The node\nanisotropies destroy the conventional picture of (anti)parallel spin and wave\nvector of a Weyl fermion. This also holds for the Berry curvature around a\nnode, while the monopole charges are independent as integrated quantities. The\npairing of the nodes strongly modify the spin texture and the Berry curvature\nfor wave vectors in between the two nodes. Spin components may change their\norientation. Integrals over planes perpendicular to the connection line yield\nfinite Zak phases and winding numbers for planes between the two nodes, thereby\nindicating the topological character.",
        "positive": "Microscopic mechanism of unusual lattice thermal transport in TlInTe$_2$: We investigate the microscopic mechanism of ultralow lattice thermal\nconductivity ($\\kappa_l$) of TlInTe$_2$ and its weak temperature dependence\nusing a unified theory of lattice heat transport that considers contributions\narising from the particle-like propagation as well as wave-like tunneling of\nphonons. While we use the Peierls-Boltzmann transport equation (PBTE) to\ncalculate the particle-like contributions ($\\kappa_l$(PBTE)), we explicitly\ncalculate the off-diagonal (OD) components of the heat-flux operator within a\nfirst-principles density functional theory framework to determine the\ncontributions ($\\kappa_l$(OD)) arising from the wave-like tunneling of phonons.\nAt each temperature, T, we anharmonically renormalize the phonon frequencies\nusing the self-consistent phonon theory including quartic anharmonicity, and\nutilize them to calculate $\\kappa_l$(PBTE) and $\\kappa_l$(OD). With the\ncombined inclusion of $\\kappa_l$(PBTE), $\\kappa_l$(OD), and additional\ngrain-boundary scatterings, our calculations successfully reproduce the\nexperimental results. Our analysis shows that large quartic anharmonicity of\nTlInTe$_2$ (a) strongly hardens the low-energy phonon branches, (b) diminishes\nthe three-phonon scattering processes at finite T, and (c) recovers the weaker\nthan T$^{-1}$ decay of the measured $\\kappa_l$."
    },
    {
        "anchor": "Vertical structure of Sb-intercalated quasifreestanding graphene on\n  SiC(0001): Using the normal incidence x-ray standing wave technique as well as low\nenergy electron microscopy we have investigated the structure of\nquasi-freestanding monolayer graphene (QFMLG) obtained by intercalation of\nantimony under the $\\left(6\\sqrt{3}\\times6\\sqrt{3}\\right)R30^\\circ$\nreconstructed graphitized 6H-SiC(0001) surface, also known as zeroth-layer\ngraphene. We found that Sb intercalation decouples the QFMLG well from the\nsubstrate. The distance from the QFMLG to the Sb layer almost equals the\nexpected van der Waals bonding distance of C and Sb. The Sb intercalation layer\nitself is mono-atomic, flat, and located much closer to the substrate, at\nalmost the distance of a covalent Sb-Si bond length. All data is consistent\nwith Sb located on top of the uppermost Si atoms of the SiC bulk.",
        "positive": "Stress and heat flux via automatic differentiation: Machine-learning potentials provide computationally efficient and accurate\napproximations of the Born-Oppenheimer potential energy surface. This potential\ndetermines many materials properties and simulation techniques usually require\nits gradients, in particular forces and stress for molecular dynamics, and heat\nflux for thermal transport properties. Recently developed potentials feature\nhigh body order and can include equivariant semi-local interactions through\nmessage-passing mechanisms. Due to their complex functional forms, they rely on\nautomatic differentiation (AD), overcoming the need for manual implementations\nor finite-difference schemes to evaluate gradients. This study demonstrates a\nunified AD approach to obtain forces, stress, and heat flux for such\npotentials, and provides a model-independent implementation. The method is\ntested on the Lennard-Jones potential, and then applied to predict cohesive\nproperties and thermal conductivity of tin selenide using an equivariant\nmessage-passing neural network potential."
    },
    {
        "anchor": "Anomalous scaling law for thermoelectric transport of 2D-confined\n  electrons in an organic molecular system: Confined electrons in low dimensions host desirable material functions for\ndownscaled electronics as well as advanced energy technologies.\nThermoelectricity is a most fascinating example, since the dimensionality\nmodifies the electron density of states dramatically, leading to enhanced\nthermopower as experimentally examined in artificial two-dimensional (2D)\nstructures. However, it is still an open question whether such an enhanced\nthermopower in low dimensions is realized in layered materials with strong 2D\ncharacters such as cuprates. Here, we report unusual enhancement of the\nthermopower in the layered organic compound $\\alpha$-(BEDT-TTF)$_2$I$_3$, where\nBEDT-TTF stands for bis(ethylenedithio)-tetrathiafulvalene. We find that the\nslope in the Jonker plot (thermopower $S$ vs. logarithm of electrical\nconductivity $\\log\\sigma$) for $\\alpha$-(BEDT-TTF)$_2$I$_3$ is significantly\nlarger than that of conventional semiconductors. Moreover, the large slope is\nalso seen in the related layered salt, demonstrating the impact of the\n2D-confined carriers in the layered organics on thermoelectricity.",
        "positive": "Tuning hole mobility in InP nanowires: Transport properties of holes in InP nanowires were calculated considering\nelectron-phonon interaction via deformation potentials, the effect of\ntemperature and strain fields. Using molecular dynamics, we simulate nanowire\nstructures, LO-phonon energy renormalization and lifetime. The valence band\nground state changes between light- and heavy-hole character, as the strain\nfields and the nanowire size are changed. Drastic changes in the mobility arise\nwith the onset of resonance between the LO-phonons and the separation between\nvalence subbands."
    },
    {
        "anchor": "Microwave magnetoabsorption in R0.6Sr0.4MnO3 (R = Pr and Nd): We report microwave magnetoabsorption (P) at room temperature in\nR0.6Sr0.4MnO3 (R = Pr and Nd) samples. P as a function of dc magnetic field\n(-2.5 kOe to +2.5 kOe) was measured for a broad frequency range (f = 0.1 - 4\nGHz) of microwave magnetic field using a vector network analyzer and a copper\nstrip coil which encloses one of the above samples. As the external dc magnetic\nfield decreased from the maximum field, P initially increases and shows a\nmaximum for a critical field and then decreases as the field approaches zero.\nThe critical field increases with increasing frequency of the microwave signal.\nLine shape analysis of the obtained spectra suggests that the observed features\nin P are caused by ferromagnetic resonance (FMR) in R = Pr and electron\nparamagnetic resonance (ESR) in R = Nd samples, which were confirmed using a\ncoplanar waveguide-based broadband magnetic resonance spectrometer.",
        "positive": "Entanglement between a muon spin and $I>\\frac{1}{2}$ nuclear spins: We report on the first example of quantum coherence between the spins of\nmuons and quadrupolar nuclei. We observe this effect in vanadium intermetallic\ncompounds which adopt the A15 crystal structure, and whose members include all\ntechnologically dominant superconductors. The entangled states are extremely\nsensitive to the local structural and electronic environments through the\nelectric field gradient at the quadrupolar nuclei. This case-study demonstrates\nthat positive muons can be used as a quantum sensing tool to probe also\nstructural and charge related phenomena in materials, even in the absence of\nmagnetic order."
    },
    {
        "anchor": "Magnetic states at the surface of alpha-Fe2O3 thin films doped with Ti,\n  Zn or Sn: The spin states at the surface of epitaxial thin films of hematite, both\nundoped and doped with 1% Ti, Sn or Zn, respectively, were probed with x-ray\nmagnetic linear dichroism (XMLD) spectroscopy. Morin transitions were observed\nfor the undoped (T_M~200 K) and Sn-doped (T_M~300 K) cases, while Zn and\nTi-doped samples were always in the high and low temperature phases,\nrespectively. In contrast to what has been reported for bulk hematite doped\nwith the tetravalent ions Sn4+ and Ti4+, for which T_M dramatically decreases,\nthese dopants substantially increase T_M in thin films, far exceeding the bulk\nvalues. The normalized Fe LII-edge dichroism for T<T_M does not strongly depend\non doping or temperature, except for an apparent increase of the peak\namplitudes for T<100 K. We observed magnetic field-induced inversions of the\ndichroism peaks. By applying a magnetic field of 6.5 T on the Ti-doped sample,\na transition into the T>T_M state was achieved. The temperature dependence of\nthe critical field for the Sn-doped sample was characterized in detail. It was\ndemonstrated the sample-to-sample variations of the Fe LIII-edge spectra were,\nfor the most part, determined solely by the spin orientation state.\nCalculations of the polarization-depedent spectra based on a spin-multiplet\nmodel were in reasonable agreement with the experiment and showed a mixed\nexcitation character of the peak structures.",
        "positive": "Defect-dependent colossal negative thermal expansion in UiO-66(Hf)\n  metal-organic framework: Thermally-densified hafnium terephthalate UiO-66(Hf) is shown to exhibit the\nstrongest isotropic negative thermal expansion (NTE) effect yet reported for a\nmetal-organic framework (MOF). Incorporation of correlated vacancy defects\nwithin the framework affects both the extent of thermal densification and the\nmagnitude of NTE observed in the densified product. We thus demonstrate that\ndefect inclusion can be used to tune systematically the physical behaviour of a\nMOF."
    },
    {
        "anchor": "Reentrant spin reorientation transition and Griffiths-like phase in\n  antiferromagnetic TbFe$_{0.5}$Cr$_{0.5}$O$_3$: The perovskite TbFe$_{0.5}$Cr$_{0.5}$O$_3$ shows two anomalies in the\nmagnetic susceptibility at $T_N$ = 257K and $T_{SR}$ = 190K which are\nrespectively, the antiferromagnetic and spin reorientation transition that\noccur in the Fe/Cr sublattice. Analysis of the magnetic susceptibility reveals\nsignatures of Griffiths-like phase in this compound. Neutron diffraction\nanalysis confirms that, as the temperature is reduced from 350K, a spin\nreorientation transition from $\\Gamma_2$ (F$_x$, C$_y$, G$_z$) to $\\Gamma_4$\n(G$_x$, A$_y$, F$_z$) occurs at $T_N$ = 257K and subsequently, a second spin\nreorientation takes place from $\\Gamma_4$ (G$_x$, A$_y$, F$_z$) to $\\Gamma_2$\n(F$_x$, C$_y$, G$_z$) at $T_{SR}$ = 190K. The $\\Gamma_2$ (F$_x$, C$_y$, G$_z$)\nstructure is stable until 7.7K where an ordered moment of 7.74(1)$\\mu_\\mathrm\nB$/Fe$^{3+}$(Cr$^{3+}$) is obtained from neutron data refinement. In addition\nto the long-range order of the magnetic structure, indication of diffuse\nmagnetic scattering at 7.7K is evident, thereby lending support to the\nGriffiths-like phase observed in susceptibility. At 7.7K, Tb develops a\nferromagnetic component along the crystallographic $a$ axis. Thermal\nconductivity, and spin-phonon coupling of TbFe$_{0.5}$Cr$_{0.5}$O$_3$ through\nRaman spectroscopy are studied in the present work. An antiferromagnetic\nstructure with ($\\uparrow \\downarrow \\uparrow \\downarrow$) arrangement of Fe/Cr\nspins is found in the ground state through first-principles energy calculations\nwhich supports the experimental magnetic structure at 7.7K. The spin-resolved\ntotal and partial density of states are determined showing that\nTbFe$_{0.5}$Cr$_{0.5}$O$_3$ is insulating with a band gap of $\\sim 0.12$ (2.4)\neV within GGA (GGA+$U$) functionals.",
        "positive": "Growth, microstructure and thermal transformation behaviour of epitaxial\n  Ni-Ti films: Epitaxial films have the potential to be used as model systems for\nfundamental investigations on the martensitic transformation in binary NiTi. In\nthis paper, we discuss growth of binary NiTi thin films on single crystalline\nMgO substrates. Sputter deposition is used to grow NiTi films. Films prepared\nby complementary preparation routes (with different deposition temperatures and\nsubsequent heat treatments) are investigated by X-ray diffraction, electron\nmicroscopy, atomic force microscopy, and electrical resistivity measurements,\nwith the aim of optimizing film properties, particularly to obtain a well\ndefined orientation of the austenitic unit cell and smooth surfaces. Our\nresults show that deposition at elevated temperatures and carefully controlled\nsubsequent heat treatments allow to produce epitaxially grown and smooth NiTi\nfilms that exhibit reversible one- or two-step martensitic transformations."
    },
    {
        "anchor": "Theory of the Stark Effect for P donors in Si: We develop a multi-valley effective mass theory for substitutional donors in\nsilicon in an inhomogeneous environment. Valley-orbit coupling is treated\nperturbatively. We apply the theory to the Stark effect in Si:P. The method\nbecomes more accurate at high fields, and it is designed to give correct\nexperimental binding energies at zero field. Unexpectedly, the ground state\nenergy for the donor electron is found to increase with electric field as a\nconsequence of spectrum narrowing of the 1s manifold. Our results are of\nparticular importance for the Kane quantum computer.",
        "positive": "Synthesis and Thermal Stability of Cubic ZnO in the Salt Nanocomposites: Cubic zinc oxide (rs-ZnO), metastable under normal conditions, was\nsynthesized from the wurtzite modification (w-ZnO) at 7.7 GPa and ~800 K in the\nform of nanoparticles isolated in the NaCl matrix. The phase transition rs-ZnO\n\\rightarrow w-ZnO in nanocrystalline zinc oxide under ambient pressure was\nexperimentally studied for the first time by differential scanning calorimetry\nand high-temperature X-ray diffraction. It was shown that the transition occurs\nin the 370-430 K temperature range and its enthalpy at 400 K is -10.2 \\pm 0.5\nkJ mol-1."
    },
    {
        "anchor": "Directional Dependence of the Electronic and Transport Properties of 2D\n  Monolayer Orthorhombic Diboron Dinitride (o-B2N2): DFT coupled with NEGF\n  Study: Tuning two dimensional nanomaterial's structural and electronic properties\nhas facilitated the new research paradigm in electronic device applications. In\nthis work, the first principles density functional theory based methods are\nused to investigate the structural, electronic, and transport properties of an\northorhombic diboron dinitride based polymorph. Interestingly, it depicts a low\nband gap semiconducting nature with a robust anisotropic behaviour compared to\nthe hexagonal boron nitride, which is an insulator and isotropic. We can also\ntune the structural and electronic properties of the semiconducting B2N2 based\nstructure through an external inplane mechanical strain. Further, by employing\nthe Landauer Buttiker approach, the electronic transmission function, and\nelectric current calculations reveal that the diboron dinitride based polymorph\nshows a robust direction dependent anisotropy of the quantum transport\nproperties. We have demonstrated the direction dependence of the electric\ncurrent in two perpendicular directions, where we have observed an electric\ncurrent ratio of around 61.75 at 0.8 V. All these findings, such as directional\ndependence anisotropy in transmission function, current voltage\ncharacteristics, and bandgap tunning, suggest that the applicability of such\nB2N2 based monolayer can be promising for futuristic electronic device\napplications.",
        "positive": "The potential of Rutherford Backscattering Spectrometry for composition\n  analysis of colloidal nanocrystals: We investigate the potential of elastic scattering of energetic ions for\ncompositional analysis of magnetic colloidal nanocrystals. Thin layers of\nnanocrystals deposited by spin coating on Si-wafers are investigated by two\ndifferent set-ups for Rutherford Backscattering Spectrometry (RBS), employing\ndifferent projectile ions (4He, 12C) and primary energies (600 keV - 8 MeV).\nThe advantages and disadvantages of the different approaches are discussed in\nterms of obtainable mass resolution, necessary primary particle fluence and\ndeposited energy. It is shown that different isotopes of transition metals can\nbe resolved by employing 8 MeV 12C3+ primary ions."
    },
    {
        "anchor": "Observation of pressure-induced Weyl state and superconductivity in a\n  chirality-neutral Weyl semimetal candidate SrSi2: Quasi-particle excitations in solids described by the Weyl equation have\nattracted significant attention in recent years. Thus far, a wide range of\nsolids that have been experimentally realized as Weyl semimetals (WSMs) lack\neither mirror or inversion symmetry. For the first time, in the absence of both\nmirror and inversion symmetry, SrSi2 has been predicted as a robust WSM by\nrecent theoretical works. Herein, supported by first-principles calculations,\nwe present systematic angle-resolved photoemission studies of undoped SrSi2 and\nCa-doped SrSi2 single crystals. Our results show no evidence of the predicted\nWeyl fermions at the kz = 0 plane or the Fermi arcs on the (001) surface. With\nexternal pressure, the electronic band structure evolved and induced Weyl\nfermions in this compound, as revealed by first-principle calculations combined\nwith electrical transport property measurements. Moreover, a superconducting\ntransition was observed at pressures above 20 GPa. Our investigations indicate\nthat the SrSi2 system is a good platform for studying topological transitions\nand correlations with superconductivity.",
        "positive": "Targeted Writing and Deleting of Magnetic Skyrmions in Two-Terminal\n  Nanowire Devices: Controllable writing and deleting of nanoscale magnetic skyrmions are key\nrequirements for their use as information carriers for next-generation memory\nand computing technologies. While several schemes have been proposed, they\nrequire complex fabrication techniques or precisely tailored electrical inputs,\nwhich limits their long-term scalability. Here we demonstrate an alternative\napproach for writing and deleting skyrmions using conventional electrical\npulses within a simple, two-terminal wire geometry. X-ray microscopy\nexperiments and micromagnetic simulations establish the observed skyrmion\ncreation and annihilation as arising from Joule heating and Oersted field\neffects of the current pulses, respectively. The unique characteristics of\nthese writing and deleting schemes, such as spatial and temporal selectivity,\ntogether with the simplicity of the 2-terminal device architecture, provide a\nflexible and scalable route to the viable applications of skyrmions."
    },
    {
        "anchor": "Mapping the magic numbers in binary Lennard-Jones clusters: Using a global optimization approach that directly searches for the\ncomposition of greatest stability, we have been able to find the particularly\nstable structures for binary Lennard-Jones clusters with up to 100 atoms for a\nrange of Lennard-Jones parameters. In particular, we have shown that just\nhaving atoms of different size leads to a remarkable stabilization of\npolytetrahedral structures, including both polyicosahedral clusters and at\nlarger sizes structures with disclination lines.",
        "positive": "Logarithmic wave-mechanical effects in polycrystalline metals: Theory\n  and experiment: Schrodinger-type wave equations with logarithmic nonlinearity occur in\nhydrodynamic models of Korteweg-type materials with capillarity and surface\ntension, which can undergo liquid-solid or liquid-gas phase transitions. One of\nthe predictions of the theory is a periodic pattern of density inhomogeneities\noccurring in the form of either bubbles (topological phase), or cells\n(non-topological phase). Such inhomogeneities are described by solitonic\nsolutions of a logarithmic wave equation, gaussons and kinks, in the vicinity\nof the liquid-solid phase transition. During the solidification process, these\ninhomogeneities become centers of nucleation, thus shaping the polycrystalline\nstructure of the metal grains. The theory predicts a Gaussian profile of\nmaterial density inside such a cell, which should manifest in a Gaussian-like\nprofile of microhardness inside a grain. We report experimental evidence of\nlarge-scale periodicity in the structure of grains in the ferrite steel\nS235/A570, copper C-Cu/C14200, austenite in steel X10CrNiTi18-10/AISI 321, and\naluminium-magnesium alloy 5083/5056; and also Gaussian-like profiles of\nmicrohardness inside an averaged grain in these materials."
    },
    {
        "anchor": "Size-selected polyynes synthesized by submerged arc discharge in water: Polyynes are linear sp-carbon chains of finite length consisting in a\nsequence of alternated single and triple bonds and displaying appealing optical\nand electronic properties. A simple, low cost and scalable production technique\nfor polyynes is the submerged arc discharge (SAD) in liquid, which so far, has\nbeen mainly exploited in organic solvents. In this work, we investigated in\ndetail SAD in water as a cheap and non-toxic solvent for the production of\npolyynes. The role of process parameters such as current (10-25 A) and voltage\n(20-25 V) in the production yield have been investigated, as well as polyynes\nstability. Polyynes terminated by hydrogen (CnH2: n=6-16) were identified by\nHigh-Performance Liquid Chromatography (HPLC) coupled with UV-Visible\nabsorption spectroscopy and with the support of density functional theory (DFT)\ncalculations. Size-selected polyynes separated by HPLC were analyzed by surface\nenhanced Raman spectroscopy (SERS). The formation process was monitored by in\nsitu SERS using an immersed fiber-optic Raman probe and employing Ag\nnanoparticles directly produced in the solution by SAD.",
        "positive": "Theory of transition from brittle to ductile fracture: In this paper, two improvements to the theory of transition from brittle to\nductile fracture developed by Langer are proposed. First, considering the\ndrastic temperature rise near the crack tip, the temperature dependence of the\nshear modulus is included to better quantify the thermally sensitive\ndislocation entanglement. Second, the parameters of the improved theory are\nidentified by the large scale least squares method. The comparison between the\nfracture toughness predicted by the theory and the values obtained in Gumbsch's\nexperiments for tungsten at different temperatures shows good agreement."
    },
    {
        "anchor": "Landauer vs. Boltzmann and Full Dispersion vs. Debye Model Evaluation of\n  Lattice Thermal Conductivity: Using a full dispersion description of phonons, the thermal conductivities of\nbulk Si and Bi2Te3 are evaluated using a Landauer approach and related to the\nconventional approach based on the Boltzmann transport equation. A procedure to\nextract a well-defined average phonon mean-free-path from the measured thermal\nconductivity and given phonon-dispersion is presented. The extracted\nmean-free-path has strong physical significance and differs greatly from simple\nestimates. The use of simplified dispersion models for phonons is discussed,\nand it is shown that two different Debye temperatures must be used to treat the\nspecific heat and thermal conductivity (analogous to the two different\neffective masses needed to describe the electron density and conductivity). A\nsimple technique to extract these two Debye temperatures is presented and the\nlimitations of the method are discussed.",
        "positive": "Spin torque building blocks: The discovery of the spin torque effect has made magnetic nanodevices\nrealistic candidates for active elements of memory devices and applications.\nMagnetoresistive effects allow the read-out of increasingly small magnetic\nbits, and the spin torque provides an efficient tool to manipulate - precisely,\nrapidly and at low energy cost - the magnetic state, which is in turn the\ncentral information medium of spintronic devices. By keeping the same magnetic\nstack, but by tuning a device's shape and bias conditions, the spin torque can\nbe engineered to build a variety of advanced magnetic nanodevices. Here we show\nthat by assembling these nanodevices as building blocks with different\nfunctionalities, novel types of computing architectures can be envisisaged. We\nfocus in particular on recent concepts such as magnonics and spintronic neural\nnetworks."
    },
    {
        "anchor": "Raisins in a Hydrogen Pie: Ultrastable Cesium and Rubidium Polyhydrides: We proposed a new method for synthesis of metal polyhydrides via\nhigh-pressure thermal decomposition of corresponding amidoboranes in diamond\nanvil cells. Within this approach, we synthesized molecular semiconducting\ncesium ($\\textit P4/nmm$-CsH$_7$, $\\textit P$1-CsH$_{15+x}$) and rubidium\n(RbH$_{9-x}$) polyhydrides with a very high hydrogen content reaching 93 at%.\nPreservation of CsH$_7$ at near ambient conditions, confirmed both\nexperimentally and theoretically, represents a significant advance in the\nstabilization of hydrogen-rich compounds. In addition, we synthesized two\ncrystal modifications of RbH$_{9-x}$ with pseudo hexagonal and pseudo\ntetragonal structures identified by synchrotron X-ray diffraction and Raman\nmeasurements. Both phases are stable at 8-10 GPa. This is an unprecedented low\nstabilization pressure for polyhydrides. These discoveries open up\npossibilities for modifying existing hydrogen storage materials to increase\ntheir efficiency.",
        "positive": "Investigation of the structural, electronic, transport and magnetic\n  properties of Co$_2$FeGa Heusler alloy nanoparticles: We report the structural, transport, electronic, and magnetic properties of\nCo$_2$FeGa Heusler alloy nanoparticles. The Rietveld refinements of x-ray\ndiffraction (XRD) data with the space group Fm$\\bar {3}$m clearly demonstrates\nthat the nanoparticles are of single phase. The particle size (D) decreases\nwith increasing the SiO$_2$ concentration. The Bragg peak positions and the\ninter-planer spacing extracted from high-resolution transmission electron\nmicroscopy image and selected area electron diffraction are in well agreement\nwith data obtained from XRD. The coercivity initially increases from 127~Oe to\n208~Oe between D = 8.5~nm and 12.5~nm, following the D$^{-3/2}$ dependence and\nthen decreases with further increasing D up to 21.5~nm with a D$^{-1}$\ndependence, indicating the transition from single domain to multidomain regime.\nThe effective magnetic anisotropic constant behaves similarly as coercivity,\nwhich confirms this transition. A complex scattering mechanisms have been\nfitted to explain the electronic transport properties of these nanoparticles.\nIn addition we have studied core-level and valence band spectra using\nphotoemission spectroscopy, which confirm the hybridization between $d$ states\nof Co/Fe. Further nanoparticle samples synthesized by co-precipitation method\nshow higher saturation magnetization. The presence of Raman active modes can be\nassociated with the high chemical ordering, which motivates for detailed\ntemperature dependent structural investigation using synchrotron radiation and\nneutron sources."
    },
    {
        "anchor": "Ionic and electronic properties of the topological insulator\n  Bi$_2$Te$_2$Se investigated using $\u03b2$-detected nuclear magnetic\n  relaxation and resonance of $^8$Li: We report measurements on the high temperature ionic and low temperature\nelectronic properties of the 3D topological insulator Bi$_2$Te$_2$Se using\nion-implanted $^8$Li $\\beta$-detected nuclear magnetic relaxation and\nresonance. With implantation energies in the range 5-28 keV, the probes\npenetrate beyond the expected range of the topological surface state, but are\nstill within 250 nm of the surface. At temperatures above ~150 K, spin-lattice\nrelaxation measurements reveal isolated $^8$Li$^{+}$ diffusion with an\nactivation energy $E_{A} = 0.185(8)$ eV and attempt frequency $\\tau_{0}^{-1} =\n8(3) \\times 10^{11}$ s$^{-1}$ for atomic site-to-site hopping. At lower\ntemperature, we find a linear Korringa-like relaxation mechanism with a field\ndependent slope and intercept, which is accompanied by an anomalous field\ndependence to the resonance shift. We suggest that these may be related to a\nstrong contribution from orbital currents or the magnetic freezeout of charge\ncarriers in this heavily compensated semiconductor, but that conventional\ntheories are unable to account for the extent of the field dependence.\nConventional NMR of the stable host nuclei may help elucidate their origin.",
        "positive": "Spin-lattice relaxation in bismuth chalcogenides: Bismuth chalcogenides Bi$_2$Se$_3$ and Bi$_2$Te$_3$ are semiconductors, which\ncan be both thermoelectric materials (TE) and topological insulators (TI).\nLattice defects arising from vacancies, impurities, or dopants in these\nmaterials are important in that they provide the charge carriers in TE\napplications and compromise the performance of these materials as TIs. We\npresent the first solid-state nuclear magnetic resonance (NMR) study of the\n$^{77}$Se and $^{125}$Te NMR resonances in polycrystalline powders of\nBi$_2$Se$_3$ and Bi$_2$Te$_3$, respectively. The spin-lattice ($T_1$)\nrelaxation is modeled by at most two exponentials. Within the framework of this\nmodel, the NMR measurement is sensitive to the distribution of native defects\nwithin these materials. One component corresponds to a stoichiometric fraction,\nan insulator with a very long $T_1$, whereas the other component is attributed\nto a sample fraction with high defect content with a short $T_1$ resulting from\ninteraction with the conduction carriers. The absence of a very long $T_1$ in\nthe bismuth telluride suggests defects throughout the sample. For the bismuth\nselenide, defect regions segregate into domains. We also find a substantial\ndifference in the short $T_1$ component for $^{125}$Te nuclei (76 ms) and\n$^{77}$Se (0.63 s) in spite of the fact that these materials have nearly\nidentical lattice structures, chemical and physical properties. Investigations\nof the NMR shift and Korringa law indicate that the coupling to the conduction\nband electrons at the chalcogenide sites is much stronger in the telluride. The\nresults are consistent with a stronger spin-orbit coupling (SOC) to the\n$p$-band electrons in the telluride. If most parameters of a given material are\nkept equal, this type of experiment could provide a useful probe of SOC in\nengineered TI materials."
    },
    {
        "anchor": "Thermal Dynamics of Graphene Edges Investigated by Polarized Raman\n  Spectroscopy: In this report, we present Raman spectroscopy investigation of the thermal\nstability and dynamics of graphene edges. It was found that graphene edges\n(both armchair and zigzag) are not stable and undergo modifications even at\ntemperature as low as 200{\\deg}C. Based on polarized Raman results, we provide\npossible structural models on how graphene edges change during annealing. The\nzigzag edges rearrange and form armchair segments that are \\pm30{\\deg} relative\nto the edge direction, while armchair edges are dominated by armchair segments\neven at annealing temperature as high as 500{\\deg}C. The modifications of edge\nstructures by thermal annealing (zigzag segments rearrange in form of armchair\nsegments) provide a flexible way to control the electronic properties of\ngraphene and graphene nanostructures.",
        "positive": "Electronic structure and band gap composition-dependence of the II-VI\n  quaternary alloys: Based on a successful description of II-VI ternary alloys, which introduces\nan empirical bowing parameter to the widely used virtual crystal approximation,\nwe set up a tight-binding Hamiltonian to describe the Zn_{1-y}Cd_ySe_{1-x}Te_x\nand Zn_{.9}Cd_{.1}S_{.07}Se_{.93} quaternary alloys. We just use a formula that\ncan be thought as a straightforward generalization of the virtual crystal\napproximation for this case. Our Hamiltonians reproduce very well the change in\nthe band gap value with the composition observed in recent experimental\nreports."
    },
    {
        "anchor": "Importance of two current model in understanding the electronic\n  transport behavior of inverse Heusler alloy: Fe 2 CoSi: Here we explore the applicability of the two current model in understanding\nthe transport behavior of Fe 2 CoSi compound by using the first principles\ncalculations in combination with the Boltzmann transport theory. The\nspin-unpolarized calculation shows large density of states (DOS) at Fermi level\n(E F) and is unable to provide the correct temperature dependence of transport\ncoefficients. The spin-polarised calculation shows reduced DOS at the E F in\nthe spin-up channel, whereas spin-dn channel have almost zero DOS at the E F .\nThe absolute value of Seebeck coefficient in the spin-up channel shows linear\nincrement with the temperature and in the spin-dn channel it varies\nnon-linearly. The electrical conductivity also shows non-linear temperature\ndependence in both the spin channels whereas, the electronic thermal\nconductivity shows linear temperature dependence. The values of transport\ncoefficients and their temperature dependence obtained by using the two current\nmodel are found to be in fairly good agreement with the experimental data.\nPresent work clearly suggests the importance of two current model in\nunderstanding the transport properties of the compound.",
        "positive": "CuSbSe2 photovoltaic devices with 3% efficiency: Recent technical and commercial successes of existing thin film solar cell\ntechnologies motivates exploration of next-generation photovoltaic (PV)\nabsorber materials. Of particular scientific interest are compounds like\nCuSbSe$_2$, which do not have the conventional tetrahedral semiconductor\nbonding. Here, we demonstrate 1.5 {\\mu}m thick CuSbSe$_2$ PV prototypes\nprepared at 380-410{\\deg}C by a self-regulated sputtering process using the\nconventional substrate device architecture. The p-type CuSbSe$_2$ absorber has\na 1.1 eV optical absorption onset, ~$10^{5}$ cm$^{-1}$ absorption coefficient\nat 0.3 eV above the onset, and a hole concentration of ~10$^{17}$ cm$^{-3}$.\nThe promising >3% energy conversion efficiency (Jsc = 20 mA/cm$^2$, FF = 0.44,\nVoc = 0.35 V) in these initial devices is limited by bulk recombination that\nlimits photocurrent, device engineering issues that affect fill factor, and a\nphotovoltage deficit that likely results from the non-ideal CuSbSe2/CdS band\noffset."
    },
    {
        "anchor": "Intrinsic structural instabilities of domain walls driven by gradient\n  couplings: meandering anferrodistortive-ferroelectric domain walls in BiFeO3: Using Landau-Ginzburg-Devonshire approach, we predict the intrinsic\ninstability of the ferroelectric-ferroelastic domain walls in the multiferroic\nBiFeO3 emerging from the interplay between the gradient terms of the\nantiferrodistortive and ferroelectric order parameters at the walls. These\ninstabilities are the interface analogue of the structural instabilities in the\nvicinity of phase coexistence in the bulk; and so they do not steam from\nincomplete polarization screening in thin films or its spatial confinement,\nelectrostrictive or flexoelectric coupling. The effect of BiFeO3 material\nparameters on the 71 degree, 109 degree, and 180 degree walls is explored, and\nit is shown that the meandering instability appears at 109 degree, and 180\ndegree walls for small gradient energies, and the walls become straight and\nbroaden for higher gradients. In contrast to the 180 degree and 109 degree\ndomain walls, uncharged 71 degree walls are always straight, and their width\nincreases with increasing the tilt gradient coefficient. The wall instability\nand associated intrinsic meandering provide a new insight into the behavior of\nmorphotropic and relaxor materials, wall pinning, and mechanisms of\ninteractions between order parameter fields and local microstructure.",
        "positive": "Pentagonal nanowires from topological crystalline insulators: a platform\n  for intrinsic core-shell nanowires and higher-order topology: We report on the experimental realization of Pb1-xSnxTe pentagonal nanowires\n(NWs) with [110] orientation using molecular beam epitaxy techniques. Using\nfirst-principles calculations, we investigate the structural stability in NWs\nof SnTe and PbTe in three different structural phases: cubic, pentagonal with\n[001] orientation and pentagonal with [110] orientation. Within a semiclassical\napproach, we show that the interplay between ionic and covalent bonds favors\nthe formation of pentagonal NWs. Additionally, we find that this pentagonal\nstructure is more likely to occur in tellurides than in selenides. The\ndisclination and twin boundary cause the electronic states originating from the\nNW core region to generate a conducting band connecting the valence and\nconduction bands, creating a symmetry-enforced metallic phase. The metallic\ncore band has opposite slopes in the cases of Sn and Te twin boundary, while\nthe bands from the shell are insulating. We finally study the electronic and\ntopological properties of pentagonal NWs unveiling their potential as a new\nplatform for higher-order topology and fractional charge. These pentagonal NWs\nrepresent a unique case of intrinsic core-shell one-dimensional nanostructures\nwith distinct structural, electronic and topological properties between the\ncore and the shell region."
    },
    {
        "anchor": "Low-voltage nanodomain writing in He-implanted lithium niobate crystals: A scanning force microscope tip is used to write ferroelectric domains in\nHe-implanted single-crystal lithium niobate and subsequently probe them by\npiezoresponse force microscopy. Investigation of cross-sections of the samples\nshowed that the buried implanted layer, $\\sim 1$\\,\\textmu m below the surface,\nis non-ferroelectric and can thus act as a barrier to domain growth. This\nbarrier enabled stable surface domains of $< 1$\\,\\textmu m size to be written\nin 500\\,\\textmu m-thick crystal substrates with voltage pulses of only 10\\,V\napplied to the tip.",
        "positive": "Molecular-orbital-free algorithm for excited states in time-dependent\n  perturbation theory: A non-linear conjugate gradient optimization scheme is used to obtain\nexcitation energies within the Random Phase Approximation (RPA). The solutions\nto the RPA eigenvalue equation are located through a variational\ncharacterization using a modified Thouless functional, which is based upon an\nasymmetric Rayleigh quotient, in an orthogonalized atomic orbital\nrepresentation. In this way, the computational bottleneck of calculating\nmolecular orbitals is avoided. The variational space is reduced to the\nphysically-relevant transitions by projections. The feasibility of an RPA\nimplementation scaling linearly with system size, N, is investigated by\nmonitoring convergence behavior with respect to the quality of initial guess\nand sensitivity to noise under thresholding, both for well- and ill-conditioned\nproblems. The molecular- orbital-free algorithm is found to be robust and\ncomputationally efficient providing a first step toward a large-scale, reduced\ncomplexity calculation of time-dependent optical properties and linear\nresponse. The algorithm is extensible to other forms of time-dependent\nperturbation theory including, but not limited to, time-dependent Density\nFunctional theory."
    },
    {
        "anchor": "Magnetodielectric effect and optic soft mode behaviour in quantum\n  paraelectric EuTiO3 ceramics: Infrared reflectivity and time-domain terahertz transmission spectra of\nEuTiO3 ceramics revealed a polar optic phonon at 6 - 300K, whose softening is\nfully responsible for the recently observed quantum paraelectric behaviour.\nEven if our EuTiO3 ceramics show lower permittivity than the single crystal due\nto a reduced density and/or small amount of secondary pyrochlore Eu2Ti2O7\nphase, we confirmed the magnetic field dependence of the permittivity, also\nslightly smaller than in single crystal. Attempt to reveal the soft phonon\ndependence at 1.8K on the magnetic field up to 13T remained below the accuracy\nof our infrared reflectivity experiment.",
        "positive": "Induced Spin-Currents in Alkali-Films: In sandwiches of FeK and FeCs the conduction electrons in the alkali metals\nhave a large mean free path. The experiments suggest that the specular\nreflection for spin up and down electrons is different at the interface\nyielding a spin current in the alkali film. The spin current is detected by the\nanomalous Hall effect of Pb surface impurities."
    },
    {
        "anchor": "Interpretation of Dynamic Nanoindentation Results a simple harmonic\n  oscillators for measurement of viscoelasticity: With the invent of nanoindentation technology capable of greater frequency of\noscillation the full resonant behaviour can be observed. Here we lay out a\nproposed mathematical basis to interpret the measured dynamic compliance of a\nsystem to discover the viscoelastic properties of test samples.",
        "positive": "Room temperature spin coherence in ZnO: Time-resolved optical techniques are used to explore electron spin dynamics\nin bulk and epilayer samples of n-type ZnO as a function of temperature and\nmagnetic field. The bulk sample yields a spin coherence time T2* of 20 ns at T\n= 30 K. Epilayer samples, grown by pulsed laser deposition, show a maximum T2*\nof 2 ns at T = 10 K, with spin precession persisting up to T = 280 K."
    },
    {
        "anchor": "Synthesis, characterization and modeling of high quality ferromagnetic\n  Cr-doped AlN thin films: We report a theoretical and experimental investigation of Cr-doped AlN.\nDensity functional calculations predict that the isolated Cr t2 defect level in\nAlN is 1/3 full, falls approximately at midgap, and broadens into an impurity\nband for concentrations over 5%. Substitutional Al1-xCrxN random alloys with\n0.05 <= x <= 0.15 are predicted to have Curie temperatures over 600 K.\nExperimentally, we have characterized and optimized the molecular beam epitaxy\nthin film growth process, and observed room temperature ferromagnetism with a\ncoercive field, Hc, of 120 Oersted. The measured magnetic susceptibility\nindicates that over 33% of the Cr is magnetically active at room temperature\nand 40% at low temperature.",
        "positive": "Confined states and direction-dependent transmission in graphene quantum\n  wells: We report the existence of confined massless fermion states in a graphene\nquantum well (QW) by means of analytical and numerical calculations. These\nstates show an unusual quasi-linear dependence on the momentum parallel to the\nQW: their number depends on the wavevector and is constrained by electron-hole\nconversion in the barrier regions. An essential difference with\nnon-relativistic electron states is a mixing between free and confined states\nat the edges of the free-particle continua, demonstrated by the\ndirection-dependent resonant transmission across a potential well."
    },
    {
        "anchor": "Unraveling the Role of Morphology on Organic Solar Cell Performance: Polymer based organic photovoltaic (OPV) technology offers a relatively\ninexpensive option for solar energy conversion provided its efficiency\nincreases beyond the current level (6-7%) along with significant improvements\nin operational lifetime. The critical aspect of such solar cells is the complex\nmorphology of distributed bulk heterojunctions, which plays the central role in\nthe conversion of photo-generated excitons to electron-hole pairs. However, the\nfabrication conditions that can produce the optimal morphology are still\nunknown due to the lack of quantitative understanding of the effects of process\nvariables on the cell morphology. In this article, we develop a unique\nprocess-device co-simulation framework based on phase-field model for phase\nseparation coupled with self-consistent drift-diffusion transport to\nquantitatively explore the effects of the process conditions (e.g., annealing\ntemperature, mixing ratio, anneal duration) on the organic solar cell\nperformance. Our results explain experimentally observed trends of open circuit\nvoltage and short circuit current that would otherwise be deemed anomalous from\nthe perspective of conventional solar cells. In addition to providing an\noptimization framework for OPV technology, our morphology-aware modeling\napproach is ideally suited for a wide class of problems involving porous\nmaterials, block co-polymers, polymer colloids, OLED devices etc.",
        "positive": "Native point defects in HgCdTe infrared detector material: Identifying\n  deep centers from first principles: We investigate the native point defects in the long-wavelength infrared\n(LWIR) detector material Hg$_{0.75}$Cd$_{0.25}$Te using a dielectric-dependent\nhybrid density functional combined with spin-orbit coupling. Characterizing\nthese point defects is essential as they are responsible for intrinsic doping\nand nonradiative recombination centers in the detector material. The\ndielectric-dependent hybrid functional allows for an accurate description of\nthe band gap ($E_g$) for Hg$_{1-x}$Cd$_{x}$Te (MCT) over the entire\ncompositional range, a level of accuracy challenging with standard hybrid\nfunctionals. Our comprehensive examination of the native point defects confirms\nthat cation vacancies $V_\\text{Hg(Cd)}$ are the primary sources of $p$-type\nconductivity in the LWIR material given their low defect formation energies and\nthe presence of a shallow acceptor level ($-$/0) near the valence-band maximum\n(VBM). In addition to the shallow acceptor level, the cation vacancies exhibit\na deep charge transition level (2$-$/$-$) situated near the midgap,\ncharacteristic of nonradiative recombination centers. Our results indicate that\nHg interstitial could also be a deep center in the LWIR MCT through a\nmetastable configuration under the Hg-rich growth conditions. While an isolated\nTe antisite does not show deep levels, the formation of\n$V_\\text{Hg}$-Te$_\\text{Hg}$ defect complex introduces a deep acceptor level\nwithin the band gap."
    },
    {
        "anchor": "Exchange and correlation near the nucleus in density functional theory: The near nucleus behavior of the exchange-correlation potential $v_{xc}({\\bf\nr})$ in Hohenberg-Kohn-Sham density functional theory is investigated. It is\nshown that near the nucleus the linear term of $O(r)$ of the spherically\naveraged exchange-correlation potential ${\\bar v}_{xc}(r)$ is nonzero, and that\nit arises purely from the difference between the kinetic energy density at the\nnucleus of the interacting system and the noninteracting Kohn-Sham system. An\nanalytical expression for the linear term is derived. Similar results for the\nexchange $v_{x}({\\bf r})$ and correlation $v_{c}({\\bf r})$ potentials are also\nobtained separately. It is further pointed out that the linear term in\n$v_{xc}({\\bf r})$ arising mainly from $v_{c}({\\bf r})$ is rather small, and\n$v_{xc}({\\bf r})$ therefore has a nearly quadratic structure near the nucleus.\nImplications of the results for the construction of the Kohn-Sham system are\ndiscussed with examples.",
        "positive": "Spin-Torque Ferromagnetic Resonance Measurements of Damping in\n  Nanomagnets: We measure the magnetic damping parameter a in thin film CoFeB and permalloy\n(Py) nanomagnets at room temperature using ferromagnetic resonance driven by\nmicrowave frequency spin-transfer torque. We obtain $\\alpha_{CoFeB} = 0.014 \\pm\n0.003$ and $\\alpha_{Py}=0.010 \\pm 0.002$, values comparable to measurements for\nextended thin films, but significantly less than the effective damping\ndetermined previously for similar nanomagnets by fits to time-domain studies of\nlarge-angle magnetic excitations and magnetic reversal. The greater damping\nfound for the large amplitude nanomagnet dynamics is attributed to the\nnonlinear excitation of non-uniform magnetic modes."
    },
    {
        "anchor": "Chaotic and power law states in the Portevin-Le Chatelier effect: Recent studies on the Portevin - Le Chatelier effect report an intriguing\ncrossover phenomenon from a low dimensional chaotic to an infinite dimensional\nscale invariant power law regime in experiments on CuAl single crystals and\nAlMg polycrystals, as a function of strain rate. We devise a fully dynamical\nmodel which reproduces these results. At low and medium strain rates, the model\nis chaotic with the structure of the attractor resembling the reconstructed\nexperimental attractor. At high strain rates, power law statistics for the\nmagnitudes and durations of the stress drops emerge as in experiments and\nconcomitantly, the largest Lyapunov exponent is zero.",
        "positive": "Electrical control of magnetism in oxides: This review article aims at illustrating the recent progresses in the\nelectrical control of magnetism in oxides with profound physics and enormous\npotential applications. In the first part, we provide a comprehensive summary\nof the electrical control of magnetism in the classic multiferroic\nheterostructures and clarify their various mechanisms lying behind. The second\npart focuses on the novel route of electric double layer gating for driving a\nsignificantly electronic phase transition in magnetic oxides by a small\nvoltage. The electric field applied on the ordinary dielectric oxide in the\nthird part is used to control the magnetic phenomenon originated from the\ncharge transfer and orbital reconstruction at the interface between dissimilar\ncorrelated oxides. At last, we analyze the challenges in electrical control of\nmagnetism in oxides, both on mechanism and practical application, which would\ninspire more in-depth researches and advance the development in this field."
    },
    {
        "anchor": "First-principles study of the impact of grain boundary formation in the\n  cathode material LiFePO4: Motivated by the need to understand the role of internal interfaces in Li\nmigration occurring in Li-ion batteries, a first principles study of a\ncoincident site lattice grain boundary in LiFePO4 cathode material and in its\ndelithiated counterpart FPO4 is performed. The structure of the investigated\ngrain boundary is obtained and the corresponding interface energy is\ncalculated. Other properties, such as ionic charges and magnetic moments,\nexcess free volume and the lifetime of positrons trapped at the interfaces, are\ndetermined and discussed. The results show that while the grain boundary in\nLiFePO4 has desired structural and bonding characteristics, the analogous\nboundary in FePO4 needs to be yet optimized to allow for an efficient Li\ndiffusion study.",
        "positive": "Terahertz electron paramagnetic resonance generalized spectroscopic\n  ellipsometry: The magnetic response of the nitrogen defect in 4H-SiC: We report on terahertz (THz) electron paramagnetic resonance generalized\nspectroscopic ellipsometry (THz-EPR-GSE). Measurements of the field and\nfrequency dependencies of the magnetic response due to the spin transitions\nassociated with the nitrogen defect in 4H-SiC are shown as an example.\nTHz-EPR-GSE dispenses with the need of a cavity, permits independently scanning\nfield and frequency parameters, and does not require field or frequency\nmodulation. We investigate spin transitions of hexagonal ($h$) and cubic ($k$)\ncoordinated nitrogen including coupling with its nuclear spin (I=1), and we\npropose a model approach for the magnetic susceptibility to account for the\nspin transitions. From the THz-EPR-GSE measurements we can fully determine the\npolarization properties of the spin transitions and we obtain $g$ and hyperfine\nsplitting parameters using magnetic field and frequency dependent Lorentzian\noscillator lineshape functions. We propose frequency-scanning THz-EPR-GSE as a\nnew and versatile method to study properties of spins in solid state materials."
    },
    {
        "anchor": "Influence of structure and cation distribution on magnetic anisotropy\n  and damping in Zn/Al doped nickel ferrites: An in-depth analysis of Zn/Al doped nickel ferrites grown by reactive\nmagnetron sputtering is relevant due to their promising characteristics for\napplications in spintronics. The material is insulating and ferromagnetic at\nroom temperature with an additional low magnetic damping. By studying the\ncomplex interplay between strain and cation distribution their impact on the\nmagnetic properties, i.e. anisotropy, damping and g-factor is unravelled. In\nparticular, a strong influence of the lattice site occupation of\nNi$^{2+}_{\\text{Td}}$ and cation coordination of Fe$^{2+}_{\\text{Oh}}$ on the\nintrinsic damping is found. Furthermore, the critical role of the incorporation\nof Zn$^{2+}$ and Al$^{3+}$ is evidenced by comparison with a sample of altered\ncomposition. Especially, the dopant Zn$^{2+}$ is evidenced as a tuning factor\nfor Ni$^{2+}_{\\text{Td}}$ and therefore unquenched orbital moments directly\ncontrolling the g-factor. A strain-independent reduction of the magnetic\nanisotropy and damping by adapting the cation distribution is demonstrated.",
        "positive": "Effect of Fermi-liquid interactions on the low-temperature de Haas - van\n  Alphen oscillations in quasi-two-dimensional conductors: In this work we present the results of theoretical analysis of the de\nHaas-van Alphen oscillations in quasi-two-dimensional conductors. We have been\nstudying the effect of the Fermi-liquid correlations of charge carriers on the\nabove oscillations. It was shown that at reasonably low temperatures and weak\nelectron scattering the Fermi-liquid interactions may cause noticeable changes\nin both amplitude and shape of the oscillations even at realistically small\nvalues of the Fermi-liquid parameters. Also, we show that the Fermi-liquid\ninteractions in the system of the charge carriers may cause magnetic\ninstability of a quasi-two-dimensional conductor near the peaks of quantum\noscillations in the electron density of states at the Fermi surface, indicating\nthe possibility for the diamagnetic phase transition within the relevant ranges\nof the applied magnetic fields."
    },
    {
        "anchor": "On the Structural and Optical Properties of Sputtered Hydrogenated\n  Amorphous Silicon Thin Films: The present work is essentially focused on the study of optical and\nstructural properties of hydrogenated amorphous silicon thin films (a-Si:H)\nprepared by radio-frequency cathodic sputtering. We examine separately the\ninfluence of hydrogen partial pressure during film deposition, and the effect\nof post-deposition thermal annealings on the main optical characteristics of\nthe layers such as refraction index, optical gap and Urbach energy. Using the\ngrazing X-rays reflectometry technique, thin film structural properties are\nexamined immediately after films deposition as well as after surface oxidation\nor annealing. We show that low hydrogen pressures allow a saturation of\ndangling bonds in the layers, while high doses lead to the creation of new\ndefects. We show also that thermal annealing under moderate temperatures\nimproves the structural quality of the deposited layers. For the films examined\njust after deposition, the role of hydrogen appears in the increase of their\ndensity. For those analysed after a short stay in the ambient, hydrogen plays a\nprotective role against the oxidation of their surfaces. This role disappears\nfor a long time stay in the ambient.\n  Keywords\n  Amorphous silicon, Grazing incidence X-rays, Hydrogen, Optical properties,\nPenetration depth, Reflectometry, Thermal annealing, Thin films.\n  PACS Numbers\n  61.10.K - 61.43.D - 68.55.JK - 68.55.81.15.A",
        "positive": "Crossing and anti-crossing effects of polaritons in a\n  magnetic-semiconductor superlattice influenced by an external magnetic field: Crossing and anti-crossing effects in dispersion characteristics of both bulk\nand surface polaritons in a magnetic-semiconductor superlattice influenced by\nan external static magnetic field being in the Faraday geometry are discussed.\nThe bulk polaritons are classified as eigenwaves with right-handed and\nleft-handed elliptically polarized states, whereas the surface polaritons are\nconsidered as hybrid modes having a predominant effect of either magnetic or\nsemiconductor subsystem, and distinctions in dispersion characteristics of such\npolaritons are revealed involving the concept of critical points."
    },
    {
        "anchor": "Stabilizing an atomically thin quantum spin Hall insulator at ambient\n  conditions: Graphene-intercalation of indenene: Atomic monolayers on semiconductor surfaces represent a new class of\nfunctional quantum materials at the ultimate two-dimensional limit, ranging\nfrom superconductors [1, 2] to Mott insulators [3, 4] and ferroelectrics [5] to\nquantum spin Hall insulators (QSHI) [6, 7]. A case in point is the recently\ndiscovered QSHI indenene [7, 8], a triangular monolayer of indium epitaxially\ngrown on SiC(0001), exhibiting a $\\sim$120meV gap and substrate-matched\nmonodomain growth on the technologically relevant $\\mu$m scale [9]. Its\nsuitability for room-temperature spintronics is countered, however, by the\ninstability of pristine indenene in air, which destroys the system along with\nits topological character, nullifying hopes of ex-situ processing and device\nfabrication. Here we show how indenene intercalation into epitaxial graphene\noffers effective protection from the oxidizing environment, while it leaves the\ntopological character fully intact. This opens an unprecedented realm of\nex-situ experimental opportunities, bringing this monolayer QSHI within\nrealistic reach of actual device fabrication and edge channel transport.",
        "positive": "Effects of dilute substitutional solutes on carbon in $\u03b1$-Fe:\n  interactions and associated carbon diffusion from first-principles\n  calculations: By means of first-principles calculations coupled with the kinetic Monte\nCarlo simulations, we have systematically investigated the effects of dilute\nsubstitutional solutes on the behaviors of carbon in $\\alpha$-Fe. Our results\nuncover that: ($i$) Without the Fe vacancy the interactions between most\nsolutes and carbon are repulsive due to the strain relief, whereas Mn has a\nweak attractive interaction with its nearest-neighbor carbon due to the local\nferromagnetic coupling effect. ($ii$) The presence of the Fe vacancy results in\nattractive interactions of all the solutes with carbon. In particular, the\nMn-vacancy pair shows an exceptionally large binding energy of -0.81 eV with\ncarbon. ($iii$) The alloying addition significantly impacts the atomic-scale\nconcentration distributions and chemical potential of carbon in the Fe matrix.\nAmong them, Mn and Cr increase the carbon chemical potential whereas Al and Si\nreduce it. ($iv$) Within the dilute scale of the alloying solution, the solute\nconcentration and temperature dependent carbon diffusivities demonstrate that\nMn has a little impact on the carbon diffusion whereas Cr (Al or Si) remarkably\nretards the carbon diffusion. Our results provide certain implication for\nbetter understanding the experimental observations related with the carbon\nsolubility limit, carbon micro-segregation and carbide precipitations in the\nferritic steels."
    },
    {
        "anchor": "Electrical excitation of silicon-vacancy centers in single crystal\n  diamond: Electrically driven emission from negatively charged silicon-vacancy, (SiV)-\ncentres in single crystal diamond is demonstrated. The SiV centres were\ngenerated using ion implantation into an intrinsic (i) region of a p-i-n single\ncrystal diamond diode. Both electroluminescence and the photoluminescence\nsignals exhibit the typical emission that is attributed to the (SiV)- centres.\nUnder forward and reversed biased PL measurements, no signal from the neutral\n(SiV)0 defect could be observed. The realization of electrically driven (SiV)-\nemission is promising for scalable nanophotonics devices employing colour\ncentres in single crystal diamond.",
        "positive": "Spatially Resolved Mapping of Local Polarization Dynamics in an Ergodic\n  Phase of Ferroelectric Relaxor: Spatial variability of polarization relaxation kinetics in relaxor\nferroelectric 0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 is studied using time-resolved\nPiezoresponse Force Microscopy. Local relaxation attributed to the\nreorientation of polar nanoregions is shown to follow stretched exponential\ndependence, exp(-(t/tau)^beta), with beta~~0.4, much larger than the\nmacroscopic value determined from dielectric spectra (beta~~0.09). The spatial\ninhomogeneity of relaxation time distributions with the presence of 100-200 nm\n\"fast\" and \"slow\" regions is observed. The results are analyzed to map the\nVogel-Fulcher temperatures on the nanoscale."
    },
    {
        "anchor": "Extraordinary electrical conductance through amorphous non-conducting\n  polymers under vibrational strong coupling: Achieving electrical conductance in amorphous non-doped polymers is a\nchallenging task. Here, we show that vibrational strong coupling of the\naromatic C-H(D) out-of-plane bending modes of polystyrene, deuterated\npolystyrene, and poly (benzyl methacrylate) to the vacuum electromagnetic field\nof the cavity enhance the electrical conductivity by at least six orders of\nmagnitude compared to the uncoupled polymers. The conductance is thermally\nactivated at the onset of strong coupling. It becomes temperature and cavity\npath length independent at the highest coupling strengths, giving rise to the\nextraordinary electrical conductance in these polymers. The electrical\ncharacterizations are performed without external light excitation,\ndemonstrating the role of quantum light in enhancing the long-range coherent\ntransport even in amorphous non-conducting polymers.",
        "positive": "Mechanical Switching of Nanoscale Multiferroic Phase Boundaries: Tuning the lattice degree of freedom in nanoscale functional crystals is\ncritical to exploit the emerging functionalities such as piezoelectricity,\nshape-memory effect, or piezomagnetism, which are attributed to the intrinsic\nlattice-polar or lattice-spin coupling. Here it is reported that a mechanical\nprobe can be a dynamic tool to switch the ferroic orders at the nanoscale\nmultiferroic phase boundaries in BiFeO 3 with a phase mixture, where the\nmaterial can be reversibly transformed between the \"soft\" tetragonal-like and\nthe \"hard\" rhombohedrallike structures. The microscopic origin of the\nnonvolatile mechanical switching of the multiferroic phase boundaries, coupled\nwith a reversible 180{\\deg} rotation of the in-plane ferroelectric\npolarization, is the nanoscale pressure-induced elastic deformation and\nreconstruction of the spontaneous strain gradient across the multiferroic phase\nboundaries. The reversible control of the room-temperature multiple ferroic\norders using a pure mechanical stimulus may bring us a new pathway to achieve\nthe potential energy conversion and sensing applications."
    },
    {
        "anchor": "Remarkable nuances of crystallization: From ordinary crystal nucleation\n  to rival mechanisms of crystallite coalescence: Crystal growth and crystal coalescence processes in supercooled systems\nstrongly depend on the concentration of crystallization centers. We perform\natomistic dynamics simulations of the crystallization process in the ultrathin\nmetallic film at different supercooling levels corresponding to supercooled\nliquid and amorphous solid states. Scaled relations are applied to identify the\ncharacteristic regimes in the time-dependent crystalline nuclei concentration:\nsteady-state nucleation regime, saturation regime and coalescence regime. We\nshow that the crystal growth at the saturation regime appears due to mixing\nnucleation and coalescence processes. We find that the crystallite coalescence\nrealizes mainly through the mechanism of restructurization/absorption of\ncrystal nuclei, whereas the mechanism of oriented attachment is manifested only\nat low levels of supercooling.",
        "positive": "Magnon-polarons in van der Waals antiferromagnet FePS3: The hybridization of magnons (spin waves) with phonons, if sufficiently\nstrong and comprising long wavelength excitations, may offer a new playground\nwhen manipulating the magnetically ordered systems with light. Applying a\nmagnetic field to a quasi-2D antiferromagnet, FePS3, we tune the magnon-gap\nexcitation towards coincidence with the initially lower-in-energy phonon modes.\nHybrid magnon-phonon modes, the magnon polarons are unveiled with demonstration\nof a pronounced avoided crossing between the otherwise bare magnon and phonon\nexcitations. The magnon polarons in FePS3 are primary traced with Raman\nscattering experiments, but, as we show, they also couple directly to terahertz\nphotons, what evokes their further explorations in the domain of\nantiferromagnetic optospintronics."
    },
    {
        "anchor": "Exciton-carrier coupling in a metal halide perovskite nanocrystal\n  assembly probed by two-dimensional coherent spectroscopy: The surface chemistry and inter-connectivity within perovskite nanocrystals\nplay a critical role in determining the electronic interactions. They manifest\nin the Coulomb screening of electron-hole correlations and the carrier\nrelaxation dynamics, among other many-body processes. Here, we characterize the\ncoupling between the exciton and free carrier states close to the band-edge in\na ligand-free formamidinium lead bromide nanocrystal assembly via\ntwo-dimensional coherent spectroscopy. The optical signatures observed in this\nwork show: (i) a nonlinear spectral lineshape reminiscent of Fano-like\ninterference that evidences the coupling between discrete electronic states and\na continuum, (ii) symmetric excited state absorption cross-peaks that suggest\nthe existence of a coupled exciton-carrier excited state, and (iii) ultrafast\ncarrier thermalization and exciton formation. Our results highlight the\npresence of coherent coupling between exciton and free carriers, particularly\nin the sub-100 femtosecond timescales.",
        "positive": "STM and ab initio study of holmium nanowires on a Ge(111) Surface: A nanorod structure has been observed on the Ho/Ge(111) surface using\nscanning tunneling microscopy (STM). The rods do not require patterning of the\nsurface or defects such as step edges in order to grow as is the case for\nnanorods on Si(111). At low holmium coverage the nanorods exist as isolated\nnanostructures while at high coverage they form a periodic 5x1 structure. We\npropose a structural model for the 5x1 unit cell and show using an ab initio\ncalculation that the STM profile of our model structure compares favorably to\nthat obtained experimentally for both filled and empty states sampling. The\ncalculated local density of states shows that the nanorod is metallic in\ncharacter."
    },
    {
        "anchor": "Quantitative theory of the grain boundary impact on the open-circuit\n  voltage of polycrystalline solar cells: Thin film polycrystalline photovoltaics are a mature, commercially-relevant\ntechnology. However, basic questions persist about the role of grain boundaries\nin the performance of these materials, and the extent to which these defects\nmay limit further progress. In this work, we first extend previous analysis of\ncolumnar grain boundaries to develop a model of the recombination current of\n\"tilted\" grain boundaries. We then consider systems with multiple, intersecting\ngrain boundaries and numerically determine the parameter space for which our\nanalytical model accurately describes the recombination current. We find that\nfor material parameters relevant for thin film photovoltaics, our model can be\napplied to compute the open-circuit voltage of materials with networks of\ninhomogeneous grain boundaries. This model bridges the gap between the\ndistribution of grain boundary properties observed with nanoscale\ncharacterization and their influence on the macroscale device open-circuit\nvoltage.",
        "positive": "Lattice Instability and Ultralow Lattice Thermal Conductivity of Layered\n  PbIF: Understanding the interplay between various design strategies (for instance,\nbonding heterogeneity and lone pair induced anharmonicity) to achieve ultralow\nlattice thermal conductivity ($\\kappa_l$) is indispensable for discovering\nnovel functional materials for thermal energy applications. In the present\nstudy, we investigate layered PbXF (X = Cl, Br, I), which offers bonding\nheterogeneity through the layered crystal structure, anharmonicity through the\nPb$^{2+}$ $6s^2$ lone pair, and phonon softening through the mass difference\nbetween F and Pb/X. The weak inter-layer van der Waals bonding and the strong\nintra-layer ionic bonding with partial covalent bonding result in a significant\nbonding heterogeneity and a poor phonon transport in the out-of-plane\ndirection. Large average Gr\\\"uneisen parameters ($\\geq$ 2.5) demonstrate strong\nanharmonicity. The computed phonon dispersions show flat bands, which suggest\nshort phonon lifetimes, especially for PbIF. Enhanced Born effective charges\nare due to cross-band-gap hybridization. PbIF shows lattice instability at a\nsmall volume expansion of 0.1$\\%$. The $\\kappa_l$ values obtained by the two\nchannel transport model are 20-50$\\%$ higher than those obtained by solving the\nBoltzmann transport equation. Overall, ultralow $\\kappa_l$ values are found at\n300 K, especially for PbIF. We propose that the interplay of bonding\nheterogeneity, lone pair induced anharmonicity, and constituent elements with\nhigh mass difference aids the design of low $\\kappa_l$ materials for thermal\nenergy applications."
    },
    {
        "anchor": "Canted Magnetic Ground State of Quarter-Doped Manganites\n  $R_{0.75}$Ca$_{0.25}$MnO$_3$ ($R$ = Y, Tb, Dy, Ho, and Er): Polycrystalline samples of the quarter-doped manganites\n$R_{0.75}$Ca$_{0.25}$MnO$_3$ ($R$ = Y, Tb, Dy, Ho, and Er) were studied by\nX-ray diffraction and AC/DC susceptibility measurements. All five samples are\northorhombic and exhibit similar magnetic properties: enhanced ferromagnetism\nbelow $T_1$ ($\\sim80$ K) and a spin glass (SG) state below $T_{SG}$ ($\\sim30$\nK). With increasing $R^{3+}$ ionic size, both $T_1$ and $T_{SG}$ generally\nincrease. The single crystal neutron diffraction results on\nTb$_{0.75}$Ca$_{0.25}$MnO$_3$ revealed that the SG state is mainly composed of\na short-range ordered version of a novel canted (i.e. noncollinear)\nantiferromagnetic spin state. Furthermore, calculations based on the double\nexchange model for quarter-doped manganites reveal that this new magnetic phase\nprovides a transition state between the ferromagnetic state and the\ntheoretically predicted spin-orthogonal stripe phase.",
        "positive": "Template-Assisted Direct Growth of 1Td/in$^2$ Bit Patterned Media: We present a method for growing bit patterned magnetic recording media using\ndirected growth of sputtered granular perpendicular magnetic recording media.\nThe grain nucleation is templated using an epitaxial seed layer which contains\nPt pillars separated by amorphous metal oxide. The scheme enables the creation\nof both templated data and servo regions suitable for high density hard disk\ndrive operation. We illustrate the importance of using a process that is both\ntopographically and chemically driven to achieve high quality media."
    },
    {
        "anchor": "Edge-Driven Phase Transitions in 2D Ice: 2D water, confined by atomically flat layered materials, may transit into\nvarious crystalline phases even at room temperature. However, to gain full\ncontrol over the crystalline state, we should not only confine water in the out\nof plane direction but also restrict its in plane motion, forming 2D water\nclusters or ribbons. One way to do this is by using an electric field, in\nparticular the intrinsic electric field of an adjacent polar material. We have\nfound that the crystalline phases of 2D water clusters placed between two\nhexagonal boron nitride hBN nanoribbons are crucially determined by the\nnanoribbons edges, the resulting polarity of the nanoribbons, and their\ninterlayer distance. We make use of density functional theory with further\nassistance of molecular dynamics simulations to establish the comprehensive\nphase diagrams demonstrating transitions between liquid and solid phases and\nbetween the states of different crystalline orders. We also show that the\ncrystalline orders are maintained when water flows between hBN channels under\nexternal pressure. Our results open a promising pathway towards the control of\nwater structure and its flow by the use of the microscopic electric field of\npolar materials.",
        "positive": "Optimization of electrospinning techniques for the realization of\n  nanofiber plastic lasers: Electrospinning technologies for the realization of active polymeric\nnanomaterials can be easily up-scaled, opening perspectives to industrial\nexploitation, and due to their versatility they can be employed to finely\ntailor the size, morphology and macroscopic assembly of fibers as well as their\nfunctional properties. Light-emitting or other active polymer nanofibers, made\nof conjugated polymers or of blends embedding chromophores or other functional\ndopants, are suitable for various applications in advanced photonics and\nsensing technologies. In particular, their almost one-dimensional geometry and\nfinely tunable composition make them interesting materials for developing novel\nlasing devices. However, electrospinning techniques rely on a large variety of\nparameters and possible experimental geometries, and they need to be carefully\noptimized in order to obtain suitable topographical and photonic properties in\nthe resulting nanostructures. Targeted features include smooth and uniform\nfiber surface, dimensional control, as well as filament alignment, enhanced\nlight emission, and stimulated emission. We here present various optimization\nstrategies for electrospinning methods which have been implemented and\ndeveloped by us for the realization of lasing architectures based on polymer\nnanofibers. The geometry of the resulting nanowires leads to peculiar\nlight-scattering from spun filaments, and to controllable lasing\ncharacteristics."
    },
    {
        "anchor": "Theoretical search for Chevrel phase based thermoelectric materials: We investigate the thermoelectric properties of some semiconducting Chevrel\nphases. Band structure calculations are used to compute thermopowers and to\nestimate of the effects of alloying and disorder on carrier mobility. Alloying\non the Mo site with transition metals like Re, Ru or Tc to reach a\nsemiconducting composition causes large changes in the electronic structure at\nthe Fermi level. Such alloys are expected to have low carrier mobilities.\n  Filling with transition metals was also found to be incompatible with high\nthermoelectric performance based on the calculated electronic structures.\n  Filling with Zn, Cu, and especially with Li was found to be favorable. The\ncalculated electronic structures of these filled Chevrel phases are consistent\nwith low scattering of carriers by defects associated with the filling. We\nexpect good mobility and high thermopower in materials with the composition\nclose to (Li,Cu)$_4$Mo$_6$Se$_8$, particularly when Li-rich, and recommend this\nsystem for experimental investigation.",
        "positive": "Two and one-dimensional honeycomb structures of silicon and germanium: Based on first-principles calculations of structure optimization, phonon\nmodes and finite temperature molecular dynamics, we predict that silicon and\ngermanium have stable, two-dimensional, low-buckled, honeycomb structures.\nSimilar to graphene, they are ambipolar and their charge carriers can behave\nlike a massless Dirac fermions due to their pi- and pi*-bands which are crossed\nlinearly at the Fermi level. In addition to these fundamental properties, bare\nand hydrogen passivated nanoribbons of Si and Ge show remarkable electronic and\nmagnetic properties, which are size and orientation dependent. These properties\noffer interesting alternatives for the engineering of diverse nanodevices."
    },
    {
        "anchor": "Amplified Stimulated Terahertz Emission at Room temperature from\n  Optically Pumped Graphene: Room temperature Terahertz stimulated emission and population inversion in\noptically pumped graphene is reported. We experimentally observe fast\nrelaxation and relatively slow recombination dynamics of photogenerated\nelectrons/holes in an exfoliated graphene on SiO2/Si substrate under pumping\nwith a 1550-nm, 80-fs pulsed fiber laser beam and probing with the\ncorresponding terahertz beam generated by optical rectification in a nonlinear\nelectro optical sensor. The time resolved electric field intensity originating\nfrom the coherent terahertz photon emission is electro-optically sampled in an\ntotal-reflection geometry. The comparison of terahertz electric fields\nintensities measured on SiO2/Si substrate and that one from graphene clearly\nindicate that graphene sheet act like an amplifying medium. The Emission\nspectra agrees relatively well the pumping photon spectrum and its dependency\non the pumping power shows a threshold like behavior, testifying the occurrence\nof the negative conductivity in the THz spectral range and the population\ninversion. The threshold pumping intensity > 5*10^6 W/cm^2 is in a good\nagreement with simulations.",
        "positive": "Polar domain walls trigger magnetoelectric coupling: Interface physics in oxide heterostructures is pivotal in material's science.\nDomain walls (DWs) in ferroic systems are examples of naturally occurring\ninterfaces, where order parameter of neighboring domains is modified and\nemerging properties may develop. Here we show that electric tuning of\nferroelastic domain walls in SrTiO3 leads to dramatic changes of the magnetic\ndomain structure of a neighboring magnetic layer (La1/2Sr1/2MnO3) epitaxially\nclamped on a SrTiO3 substrate. We show that by exploiting the resposiveness of\nDWs nanoregions to external stimuli, even in absence of any domain\ncontribution, prominent and adjustable macroscopic reactions of neighboring\nlayers can be obtained. We conclude that polar DWs, known to exist in other\nmaterials, can be used to trigger tunable responses and may lead to new ways\nfor manipulation of interfacial emerging properties."
    },
    {
        "anchor": "Half-metallic, Co-based quaternary Heuslers for spintronics: defect- and\n  pressure-induced transitions and properties: Heusler compounds offer potential as spintronic devices due to their\nspin-polarization and half-metallicity properties, where electron spin-majority\n(minority) manifold exhibits states (band gap) at the electronic chemical\npotential, yielding full spin-polarization in a single manifold. Yet, Heuslers\noften exhibit intrinsic disorder that degrades its half-metallicity and\nspin-polarization. Using density-functional theory, we analyze the electronic\nand magnetic properties of equiatomic Heusler ($L$2$_{1}$) CoMnCrAl and\nCoFeCrGe alloys for effects of hydrostatic pressure and intrinsic disorder\n(thermal antisites, binary swaps, and vacancies). Under pressure, CoMnCrAl\nundergoes a metallic transition, while half-metallicity in CoFeCrGe is retained\nfor a limited range. Antisite disorder between Co-Al pairs in CoMnCrAl and\nCo-Ge pairs in CoFeCrGe is energetically the most favored, and retain\nhalf-metallic character in Co-excess samples. However, Co-deficient samples\nundergo a transition from half-metallic to metallic, with a discontinuity in\nthe saturation magnetization. For binary swaps, configurations that compete\nwith the ground state are identified and show no loss of half-metallicity;\nhowever, the minority-spin bandgap and magnetic moments vary depending on the\natoms swapped. For single binary swaps, there is a significant energy cost in\nCoMnCrAl but with no loss of half metallicity. Although a few configurations in\nCoFeCrGe energetically compete with the ground statei, however the\nminority-spin bandgap and magnetic moments vary depending on the atoms swapped.\nThese informations should help in controlling these potential spintronic\nmaterials.",
        "positive": "Resonant thermal energy transfer to magnons in a ferromagnetic nanolayer: Energy harvesting is a modern concept which makes dissipated heat useful by\ntransferring thermal energy to other excitations. Most of the existing\nprinciples for energy harvesting are realized in systems which are heated\ncontinuously, for example generating DC voltage in thermoelectric devices. Here\nwe present the concept of high-frequency energy harvesting where the dissipated\nheat in a sample excites resonant magnons in a 5-nm thick ferromagnetic metal\nlayer. The sample is excited by femtosecond laser pulses with a repetition rate\nof 10 GHz which results in temperature modulation at the same frequency with\namplitude ~0.1 K. The alternating temperature excites magnons in the\nferromagnetic nanolayer which are detected by measuring the net magnetization\nprecession. When the magnon frequency is brought onto resonance with the\noptical excitation, a 12-fold increase of the amplitude of precession indicates\nefficient resonant heat transfer from the lattice to coherent magnons. The\ndemonstrated principle may be used for energy harvesting in various nanodevices\noperating at GHz and sub-THz frequency ranges."
    },
    {
        "anchor": "Tremendous tunneling magnetoresistance effects based on van der Waals\n  room-temperature ferromagnet Fe$_3$GaTe$_2$ with highly spin-polarized Fermi\n  surfaces: Recently, van der Waals (vdW) magnetic heterostructures have received\nincreasing research attention in spintronics. However, the lack of\nroom-temperature magnetic order of vdW material has largely impedes its\ndevelopment in practical spintronics devices. Inspired by the recently\ndiscovered vdW ferromagnet Fe3GaTe2, which has been shown to have magnetic\norder above room temperature and sizable perpendicular magnetic anisotropy, we\ninvestigate the basic electronic structure and magnetic properties of Fe3GaTe2\nas well as tunneling magnetoresistance effect in magnetic tunnel junctions\n(MTJs) with structure of Fe3GaTe2/Insulator/Fe3GaTe2 by using first-principles\ncalculations. It is found that Fe3GaTe2 with highly spin-polarized Fermi\nsurface ensures that such magnetic tunnel junctions may have prominent\ntunneling magnetoresistance effect at room temperature even comparable to\nexisting conventional AlOx and MgO-based MTJs. Our results suggest that\nFe3GaTe2-based MTJs may be the promising candidate for realizing long-waiting\nfull magnetic vdW spintronic devices.",
        "positive": "Structural and electronic properties of Pb1-xCdxTe and Pb1-xMnxTe\n  ternary alloys: A systematic theoretical study of two PbTe-based ternary alloys, Pb1-xCdxTe\nand Pb1-xMnxTe, is reported. First, using ab initio methods we study the\nstability of the crystal structure of CdTe - PbTe solid solutions, to predict\nthe composition for which rock-salt structure of PbTe changes into zinc-blende\nstructure of CdTe. The dependence of the lattice parameter on Cd (Mn) content x\nin the mixed crystals is studied by the same methods. The obtained decrease of\nthe lattice constant with x agrees with what is observed in both alloys. The\nband structures of PbTe-based ternary compounds are calculated within a\ntight-binding approach. To describe correctly the constituent materials new\ntight-binding parameterizations for PbTe and MnTe bulk crystals as well as a\ntight-binding description of rock-salt CdTe are proposed. For both studied\nternary alloys, the calculated band gap in the L point increases with x, in\nqualitative agreement with photoluminescence measurements in the infrared. The\nresults show also that in p-type Pb1-xCdxTe and Pb1-xMnxTe mixed crystals an\nenhancement of thermoelectrical power can be expected."
    },
    {
        "anchor": "Gallium vacancy and the residual acceptor in undoped GaSb studied by\n  positron lifetime spectroscopy and photoluminescence: Positron lifetime, Photoluminescence and Hall measurements were performed to\nstudy undoped p-type gallium antimonide materials. A 314ps lifetime component,\nattributed to $V_{Ga}$ related defect, was identified in the positron lifetime\nmeasurement. In the PL measurement, a $778meV$ and a $797meV$ peaks were\nobserved. Isochronal annealing studies were performed and at the temperature of\n$300^{o}C$, both the 314ps positron lifetime component and the two PL signals\ndisappeared, which gives a clear and strong evidence for their correlation.\nHowever, the hole concentration ($\\sim 2\\times 10^{17}cm^{-3}$) was observed to\nbe constant throughout the whole annealing temperature range up to $500^{o}C$.\nContradictory to general belief, this implies, at least for samples with\nannealing temperatures above $300^{o}C$, the Ga vacancy is not the acceptor\nresponsible for the p-type conduction.",
        "positive": "Double Vibronic process in the quantum spin ice candidate\n  Tb$_2$Ti$_2$O$_7$ revealed by terahertz spectroscopy: The origin of quantum fluctuations responsible for the spin liquid state in\nTb$_2$Ti$_2$O$_7$ has remained a long standing problem. By synchrotron-based\nterahertz measurements, we show evidence of strong coupling between the\nmagnetic and lattice degrees of freedom that provides a path to the quantum\nmelting process. As revealed by hybrid crystal electric field-phonon\nexcitations that appear at 0.67 THz below 200 K, and around 0.42 THz below 50\nK, the double vibronic process is unique for Tb$^{3+}$ in the titanate family\ndue to adequate energy matching and strong quadrupolar moments. The results\nsuggest that lattice motion can indeed be the driving force behind spin flips\nwithin the hybridized ground and first excited states, promoting quantum terms\nin the effective Hamiltonian that describes Tb$_2$Ti$_2$O$_7$."
    },
    {
        "anchor": "Large Intrinsic Valley Polarization and High Curie Temperature in Stable\n  Two-dimensional Ferrovalley YX$_2$(X=I,Br and Cl): Ferrovalley materials with spontaneous valley polarization are crucial to\nvalleytronic application. Based on first-principles calculations, we\ndemonstrate that two-dimensional (2D) YX$_2$(X= I, Br,and Cl) in 2H structure\nconstitute a series of promising ferrovalley semiconductors with large\nspontaneous valley polarization and high Curie temperature. Our calculations\nreveal that YX$_2$ are dynamically and thermally stable 2D ferromagnetic\nsemiconductors with a Curie temperature above 200 K. Due to the natural\nnoncentrosymmetric structure, intrinsic ferromagnetic order and strong spin\norbital coupling, the large spontaneous valley polarizations of 108.98, 57.70\nand 22.35 meV are also predicted in single-layer YX$_2$(X = I, Br and\nCl),respectively. The anomalous valley Hall effect is also proposed based on\nthe valley contrasting Berry curvature. Moreover, the ferromagnetism and valley\npolarization are found to be effectively tuning by applying a biaxial strain.\nInterestingly, the suppressed valley physics of YBr$_2$ and YCl$_2$ can be\nswitched on via applying a moderate compression strain. The present findings\npromise YX$_2$ as competitive candidates for the further experimental studies\nand practical applications in valleytronics.",
        "positive": "Switchable anomalous Hall effects in polar-stacked 2D antiferromagnet\n  MnBi2Te4: Van der Waals (vdW) assembly allows controlling symmetry of two-dimensional\n(2D) materials that determines their physical properties. Especially\ninteresting is the recently demonstrated breaking inversion symmetry by polar\nlayer stacking to realize novel electronic, magnetic, and transport properties\nof 2D vdW materials switchable by induced electric polarization. Here, based on\nsymmetry analyses and density-functional calculations, we explore the emergence\nof the anomalous Hall effect (AHE) in antiferromagnetic MnBi2Te4 films\nassembled by polar layer stacking. We demonstrate that breaking PT symmetry in\nan MnBi2Te4 bilayer makes this 2D material magnetoelectric and produces a\nspontaneous AHE switchable by electric polarization. We find that reversable\npolarization at one of the interfaces in a three-layer MnBi2Te4 film drives a\nmetal-insulator transition, as well as switching between an AHE and quantum AHE\n(QAHE). Finally, we predict that engineering an interlayer polarization in a\nthree-layer MnBi2Te4 film allows converting MnBi2Te4 from a trivial insulator\nto a Chern insulator. Overall, our work emphasizes the emergence of\nquantum-transport phenomena in 2D vdW antiferromagnets by polar layer stacking,\nwhich do not exist in this material in the bulk or bulk-like thin-film forms."
    },
    {
        "anchor": "Thermally induced changes of structure in\n  Ni$_{50}$Mn$_{25+x}$Ga$_{25-x}$ magnetic shape memory single crystals with\n  very low twinning stress: In search for the origins of the extraordinary low twinning stress of\nNi-Mn-Ga magnetic shape memory alloys we studied the thermally induced changes\nof structure in Ni$_{50}$Mn$_{25+x}$Ga$_{25-x}$ ($x$=2.7--3.9) single crystal\nsamples and compared them with twinning stress dependences. The alloys\nexhibited transformation to five-layered (10M) martensite structure between 297\nto 328 K. All samples exhibited magnetic shape memory effect. Just below the\ntransformation temperature the samples had very low twinning stress of about\n0.1--0.3 MPa, which increased with decreasing temperature. The structural\nchanges were monitored using X-ray diffraction in the temperature range\n173--343 K. The 10M structure was approximated by monoclinic lattice with the\nunit cell derived from the cubic unit cell of the parent L2$_{1}$ phase. With\ndecreasing temperature, the lattice parameters $a$ and $\\gamma$ increased, $c$\ndecreased, while $b$ was nearly constant. For $x\\leq3.5$, sudden sharp changes\nin $a$ and $b$ parameters additionally occurred, resulting in $a=b$ in some\nregions of the phase diagram, which might be related to the refinement of twin\nstructure of 10M martensite on nanoscale. The temperature dependences of\nlattice parameter $\\gamma$ (and $c$ or $c/a$) correlate well with the\ntemperature dependences of twinning stress in agreement with the prediction by\na microstructural model of twin boundary motion. On the contrary, there is no\ncorrelation between $(a-b)$ and twinning stress. This indicates no significant\nrole of $a/b$ twins or laminate in twin boundary motion mechanism and low\ntwinning stress.",
        "positive": "Optical spectra from molecules to crystals: Insight from many-body\n  perturbation theory: Time-dependent density-functional theory (TDDFT) often successfully\nreproduces excitation energies of finite systems, already in the adiabatic\nlocal-density approximation (ALDA). Here we show for prototypical molecular\nmaterials, i.e., oligothiophenes, that ALDA largely fails and explain why this\nis so. By comparing TDDFT with an in-depth analysis based on many-body\nperturbation theory, we demonstrate that correlation effects crucially impact\nenergies and character of the optical excitations not only for molecules of\nincreasing length and in crystalline environment, but even for isolated small\nmolecules. We argue that only high-level methodologies, which explicitly\ninclude correlation effects, can reproduce optical spectra of molecular\nmaterials with equal accuracy from gas phase to crystal structures."
    },
    {
        "anchor": "Soft X-ray Magnetic Circular Dichroism of c(2x2) CuMn Ordered Surface\n  Alloy: Mn 2p soft X-ray absorption (XAS) spectroscopy excited with circularly\npolarized synchrotron radiation has been applied to a new class of material,\nc(2x2)CuMn/Cu(001) two-dimensional ordered surface alloy. A significant X-ray\nmagnetic circular dichroism (XMCD) signal has been clearly observed at T=25K,\nindicating the existence of the ferromagnetic state under the external magnetic\nfield of 1.4 Tesla. The lineshape analyses of the XAS and XMCD spectra clearly\nshow that the Mn 3d state is rather localized and has a high spin magnetic\nmoment due to its half-filled character.",
        "positive": "Electronic structure of the c(4 x 2) reconstructed Ge(001) surface: We investigate the electronic structure of the c(4 x 2) reconstructed Ge(001)\nsurface using band structure calculations based on density functional theory\nand the generalized gradient approximation. In particular, we take into account\nthe details of surface reconstruction by means of well relaxed crystal\nstructures. The surface electronic states are identified and the local density\nof states is compared to recent data from scanning tunneling spectroscopy. We\nobtain almost perfect agreement between theory and experiment for both the\noccupied and unoccupied states, which allows us to clarify the interpretation\nof the experimental data."
    },
    {
        "anchor": "Observation of highly anisotropic bulk dispersion and spin-polarized\n  topological surface states in CoTe2: We present CoTe2 as a new type-II Dirac semimetal supporting Lorentz symmetry\nviolating Dirac fermions in the vicinity of the Fermi energy. By combining\nfirst principle ab-initio calculations with experimental angle-resolved\nphoto-emission spectroscopy results, we show the CoTe2 hosts a pair of type-II\nDirac fermions around 90 meV above the Fermi energy. In addition to the bulk\nDirac fermions, we find several topological band inversions in bulk CoTe2,\nwhich gives rise to a ladder of spin-polarized surface states over a wide range\nof energies. In contrast to the surface states which typically display\nRashba-type in-plane spin splitting, we find that CoTe2 hosts novel\nout-of-plane spin polarization as well. Our work establishes CoTe2 as a\npotential candidate for the exploration of Dirac fermiology and applications in\nspintronic devices, infrared plasmonics, and ultrafast optoelectronics.",
        "positive": "The origin of the vanadium dioxide transition entropy: The reversible metal-insulator transition in VO$_2$ at $T_\\text{C} \\approx\n340$ K has been closely scrutinized yet its thermodynamic origin remains\nambiguous. We discuss the origin of the transition entropy by calculating the\nelectron and phonon contributions at $T_\\text{C}$ using density functional\ntheory. The vibration frequencies are obtained from harmonic phonon\ncalculations, with the soft modes that are imaginary at zero temperature\nrenormalized to real values at $T_\\text{C}$ using experimental information from\ndiffuse x-ray scattering at high-symmetry wavevectors. Gaussian Process\nRegression is used to infer the transformed frequencies for wavevectors across\nthe whole Brillouin zone, and in turn compute the finite temperature phonon\npartition function to predict transition thermodynamics. Using this method, we\npredict the phase transition in VO$_2$ is driven five to one by phonon entropy\nover electronic entropy, and predict a total transition entropy that accounts\nfor $95$ % of the calorimetric value."
    },
    {
        "anchor": "Magnetism of sodium superoxide: By combining first-principles electronic-structure calculations with the\nmodel Hamiltonian approach, we systematically study the magnetic properties of\nsodium superoxide (NaO2), originating from interacting superoxide molecules. We\nshow that NaO2 exhibits a rich variety of magnetic properties, which are\ncontrolled by relative alignment of the superoxide molecules as well as the\nstate of partially filled antibonding molecular \\pi_g-orbitals. The orbital\ndegeneracy and disorder in the high-temperature pyrite phase gives rise to weak\nisotropic antiferromagnetic (AFM) interactions between the molecules. The\ntransition to the low-temperature marcasite phase lifts the degeneracy, leading\nto the orbital order and formation of the quasi-one-dimensional AFM spin\nchains. Both tendencies are consistent with the behavior of experimental\nmagnetic susceptibility data. Furthermore, we evaluate the magnetic transition\ntemperature and type of the long-range magnetic order in the marcasite phase.\nWe argue that this magnetic order depends on the behavior of weak isotropic as\nwell as anisotropic and Dzyaloshinskii-Moriya exchange interactions between the\nmolecules. Finally, we predict the existence of a multiferroic phase, where the\ninversion symmetry is broken by the long-range magnetic order, giving rise to\nsubstantial ferroelectric polarization.",
        "positive": "Definitive Evidence of Interlayer Coupling Between (Ga,Mn)As Layers\n  Separated by a Nonmagnetic Spacer: We have used polarized neutron reflectometry to study the structural and\nmagnetic properties of the individual layers in a series of\n(Al,Be,Ga)As/(Ga,Mn)As/GaAs/(Ga,Mn)As multilayer samples. Structurally, we\nobserve that the samples are virtually identical except for the GaAs spacer\nthickness (which varies from 3-12 nm), and confirm that the spacers contain\nlittle or no Mn. Magnetically, we observe that for the sample with the thickest\nspacer layer, modulation doping by the(Al,Be,Ga)As results in (Ga,Mn)As layers\nwith very different temperature dependent magnetizations. However, as the\nspacer layer thickness is reduced, the temperature dependent magnetizations of\nthe top an bottom (Ga,Mn)As layers become progressively more similar - a trend\nwe find to be independent of the crystallographic direction along which spins\nare magnetized. These results definitively show that (Ga,Mn)As layers can\ncouple across a non-magnetic spacer, and that such coupling depends on spacer\nthickness."
    },
    {
        "anchor": "Strain driven sequential magnetic transitions in strained GdTiO3 on\n  compressive substrates: a first-principles study: The compressive strain effects on the magnetic ground state and electronic\nstructure of strained GdTiO 3 have been studied by the first-principles method.\nDifferent from the congeneric YTiO3 and LaTiO3 cases both of which becomes the\nA-type antiferromagnetism on the (001) LaAlO3 substrate despite their\ncontrastive magnetism, the ground state of strained GdTiO3 on the LaAlO3\nsubstrate changes from the original ferromagnetism to G-type antiferromagnetim,\ninstead of the A-type one although Gd 3+ is between Y3+ and La3+. Only when the\nin-plane compressive strain is large enough, e.g. on the (001) YAlO3 substrate,\nthe ground state finally becomes the A-type one. The band structure calculation\nshows that these compressive strained GdTiO3 remain insulating, although the\nband gap changes a little in these strained GdTiO3.",
        "positive": "Spin-dependent tunneling in modulated structures of (Ga,Mn)As: A model of coherent tunneling, which combines multi-orbital tight-binding\napproximation with Landauer-B\\\"uttiker formalism, is developed and applied to\nall-semiconductor heterostructures containing (Ga,Mn)As ferromagnetic layers. A\ncomparison of theoretical predictions and experimental results on\nspin-dependent Zener tunneling, tunneling magnetoresistance (TMR), and\nanisotropic magnetoresistance (TAMR) is presented. The dependence of spin\ncurrent on carrier density, magnetization orientation, strain, voltage bias,\nand spacer thickness is examined theoretically in order to optimize device\ndesign and performance."
    },
    {
        "anchor": "Tuning the vertical location of helical surface states in topological\n  insulator heterostructures via dual-proximity effects: In integrating topological insulators (TIs) with conventional materials, one\ncrucial issue is how the topological surface states (TSS) will behave in such\nheterostructures. We use first-principles approaches to establish accurate\ntunability of the vertical location of the TSS via intriguing dual-proximity\neffects. By depositing a conventional insulator (CI) overlayer onto a TI\nsubstrate (Bi2Se3 or Bi2Te3), we demonstrate that, the TSS can float to the top\nof the CI film, or stay put at the CI/TI interface, or be pushed down deeper\ninto the otherwise structurally homogeneous TI substrate. These contrasting\nbehaviors imply a rich variety of possible quantum phase transitions in the\nhybrid systems, dictated by key material-specific properties of the CI. These\ndiscoveries lay the foundation for accurate manipulation of the real space\nproperties of TSS in TI heterostructures of diverse technological significance.",
        "positive": "Model for High Temperature Phase of C70 Solid: Depending on the temperature, the C70 solid crystallizes in several\nstructures. At high temperature (T > 340K), the ellipsoidal C70 molecule\nrotates freely in all directions and may be treated as a uniform thick\nspherical shell with inner and outer radii as the minimum and the maximum\ndistance of C-atom from the center of the molecule. At lower temperatures the\nfree rotations of molecules freeze out. We have calculated the lattice\nparameters, energies and bulk modulus at the minimum energy configuration of\nfcc and hcp phase of pure C70 solid at high temperature using a simple model\nbased on atom-atom potential."
    },
    {
        "anchor": "Magnetic and structural anisotropies of Co2FeAl Heusler alloy epitaxial\n  thin films: This paper shows the correlation between chemical order, lattice strains and\nmagnetic properties of Heusler Co2FeAl films epitaxially grown on MgO(001). A\ndetailed magnetic characterization has been performed using vector field\nmagnetometery combined with numerical Stoner-Wohlfarth analysis. We demonstrate\nthe presence of three types of in-plane anisotropies: one biaxial, as expected\nfor the cubic symmetry, and other two uniaxial ones. The three anisotropies\nshow different behavior with the annealing temperature. The biaxial anisotropy\nshows a monotonous increase. The uniaxial anisotropy, parallel with the hard\nbiaxial axes, related to the chemical homogeneity, decreases, while the other,\nsupposed to have magnetostatic origin, remains constant.",
        "positive": "Opening the band gap of graphene through silicon doping for improved\n  performance of graphene/GaAs heterojunction solar cells: Graphene has attracted increasing interests due to its remarkable properties,\nhowever, the zero band gap of monolayer graphene might limit its further\nelectronic and optoelectronic applications. Herein, we have successfully\nsynthesized monolayer silicon-doped graphene (SiG) in large area by chemical\nvapor deposition method. Raman spectroscopy and X-ray photoelectron\nspectroscopy measurements evidence silicon atoms are doped into graphene\nlattice with the doping level of 3.4 at%. The electrical measurement based on\nfield effect transistor indicates that the band gap of graphene has been opened\nby silicon doping, which is around 0. 28 eV supported by the first-principle\ncalculations, and the ultraviolet photoelectron spectroscopy demonstrates the\nwork function of SiG is 0.13 eV larger than that of graphene. Moreover, the\nSiG/GaAs heterostructure solar cells show an improved power conversion\nefficiency of 33.7% in average than that of graphene/GaAs solar cells, which\nare attributed to the increased barrier height and improved interface quality.\nOur results suggest silicon doping can effectively engineer the band gap of\nmonolayer graphene and SiG has great potential in optoelectronic device\napplications."
    },
    {
        "anchor": "Multipurpose and Reusable Ultrathin Electronic Tattoos Based on PtSe2\n  and PtTe2: Wearable bioelectronics with emphasis on the research and development of\nadvanced person-oriented biomedical devices have attracted immense interest in\nthe last decade. Scientists and clinicians find it essential to utilize\nskin-worn smart tattoos for on-demand and ambulatory monitoring of an\nindividual's vital signs. Here we report on the development of novel ultrathin\nplatinum-based two-dimensional dichalcogenide (Pt-TMDs) based electronic\ntattoos as advanced building blocks of future wearable bioelectronics. We made\nthese ultrathin electronic tattoos out of large-scale synthesized platinum\ndiselenide (PtSe2) and platinum ditelluride (PtTe2) layered materials and used\nthem for monitoring human physiological vital signs, such as the electrical\nactivity of the heart and the brain, muscle contractions, eye movements, and\ntemperature. We show that both materials can be used for these applications;\nyet, PtTe2 was found to be the most suitable choice due to its metallic\nstructure. In terms of sheet resistance, skin-contact, and electrochemical\nimpedance, PtTe2 outperforms state-of-the-art gold and graphene electronic\ntattoos and performs on par with medical-grade Ag/AgCl gel electrodes. The\nPtTe2 tattoos show four times lower impedance and almost 100 times lower sheet\nresistance compared to monolayer graphene tattoos. One of the possible prompt\nimplications of the work is perhaps in the development of advanced\nhuman-machine interfaces. To display the application, we built a multi-tattoo\nsystem that can easily distinguish eye movement and identify the direction of\nan individual's sight.",
        "positive": "Evidence for percolation diffusion of cations and material recovery in\n  disordered pyrochlore from accelerated molecular dynamics simulations: We used classical and accelerated molecular dynamics simulations to\ncharacterize vacancy-mediated diffusion of cations in Gd$_2$Ti$_2$O$_7$\npyrochlore as a function of the disorder on the microsecond timescale. We find\nthat cation vacancy diffusion is slow in materials with low levels of disorder.\nHowever, higher levels of disorder allow for fast cation diffusion, which is\nthen also accompanied by fast antisite annihilation and ordering of the\ncations. The cation diffusivity is therefore not constant, but decreases as the\nmaterial reorders. The results suggest that fast cation diffusion is triggered\nby the existence of a percolation network of antisites. This is in marked\ncontrast with oxygen diffusion, which showed a smooth increase of the ionic\ndiffusivity with increasing disorder in the same compound. The increase of the\ncation diffusivity with disorder is also contrary to observations from other\ncomplex oxides and disordered media models, suggesting a fundamentally\ndifferent relation between disorder and mass transport. These results highlight\nthe dynamic interplay between fast cation diffusion and the recovery of\ndisorder and have important implications for understanding radiation damage\nevolution, sintering and aging, as well as diffusion in disorder oxides more\ngenerally."
    },
    {
        "anchor": "A substantial increase of Curie temperature in a new type of diluted\n  magnetic semiconductors via effects of chemical pressure: Chemical pressure is an effective method to tune physical properties,\nparticularly for diluted magnetic semiconductors (DMS) of which ferromagnetic\nordering is mediated by charge carriers. Via substitution of smaller Ca for\nlarger Sr, we introduce chemical pressure on (Sr,Na)(Cd,Mn)2As2 to fabricate a\nnew DMS material (Ca,Na)(Cd,Mn)2As2. Carriers and spins are introduced by\nsubstitutions of (Ca,Na) and (Cd,Mn) respectively. The unit cell volume reduces\nby 6.2% after complete substitution of Ca for Sr, suggesting a subsistent\nchemical pressure. Importantly the local geometry of [Cd/MnAs4] tetrahedron is\noptimized via chemical compression that increases the Mn-As hybridization\nleading to enhanced ferromagnetic interactions. As a result, the maximum Curie\ntemperature (TC) is increased by about 50% while the the maximum saturation\nmoment increases by over 100% from (Sr,Na)(Cd,Mn)2As2 to (Ca,Na)(Cd,Mn)2As2.\nThe chemical pressure estimated from the equation of state is equal to an\nexternal physical pressure of 3.6 GPa.",
        "positive": "Energy Consumption Modeling for DED-based Hybrid Additive Manufacturing: The awareness of energy consumption is gaining much more attention in\nmanufacturing due to its economic and sustainability benefits. An energy\nconsumption model is needed for quantifying the consumption and predicting the\nimpact of various process parameters in manufacturing. This paper aims to\ndevelop an energy consumption model for Direct Energy Deposition (DED) based\nHybrid Additive Manufacturing (HAM) for an Inconel 718 part. The Specific\nEnergy Consumption (SEC) is used while developing the energy consumption of the\nproduct manufacturing lifecycle. This study focuses on the analysis to\ninvestigate three significant factors (scanning speed, laser power, and feed\nrate), their interactions' effects, and whether they have a significant\neffect.in energy consumption. The results suggest that all the factors have a\nstrong influence, but their interaction effects have a weak influence on the\nenergy consumption for HAM. Among the three process parameters, it is found\nthat laser power has the most significant effect on energy consumption. Again,\nbased on the regression analysis, this study also recommends high scanning\nspeed while the laser power and feed rate should be low. Also, idle time has\nsignificant energy consumption during the whole HAM process."
    },
    {
        "anchor": "Magneto-photoluminescence of charged excitons from MgZnO/ZnO\n  heterojunctions: We report on the photoluminescence (PL) properties of MgZnO/ZnO\nheterojunctions grown by plasma-assisted molecular-beam epitaxy. Influence of\nthe applied magnetic field (B) on the radiative recombination of the\ntwo-dimensional electron gas (2DEG) is investigated up to 54 T. An increase in\nmagnetic field in the range of B <= 20 T results in a redshift in the PL.\nAbrupt lineshape changes in the PL spectra are observed at higher magnetic\nfields, in correlation with the integer quantum Hall states. We attempt to\ninterpret these features using the conventional model for the 2DEG-related PL\nbased on the transition between the 2DEG and a hole as well as a model taking a\nbound state effect into account, i.e., a charged exciton. The comparison about\nthe adequateness of these models was made, being in favor of the charged\nexciton model.",
        "positive": "Using silicon-vacancy centers in diamond to probe the full strain tensor: An ensemble of silicon vacancy centers in diamond (\\ce{SiV-}) is probed using\ntwo coherent spectroscopy techniques. Two main distinct families of \\ce{SiV-}\ncenters are identified using multidimensional coherent spectroscopy, and these\nfamilies are paired with two orientation groups by comparing spectra from\ndifferent linear polarizations of the incident laser. By tracking the peak\ncenters in the measured spectra, the full diamond strain tensor is calculated\nlocal to the laser spot. Such measurements are made at multiple points on the\nsample surface and variations in the strain tensor are observed."
    },
    {
        "anchor": "Sn1-xBixO2 and Sn1-xTaxO2 (0 \\leq x \\leq 0.75): A first-principles study: The structural, elastic, electronic and optical (x = 0) properties of doped\nSn1-xBixO2 and Sn1-xTaxO2 (0 \\leq x \\leq 0.75) are studied by using the\nfirst-principles pseudopotential plane-wave method within the local density\napproximation. The independent elastic constants Cij and other elastic\nparameters of these compounds have been calculated for the first time. The\nmechanical stability of the compounds with different doping concentrations has\nalso been studied. The electronic band structure and density of states are\ncalculated and the effect of doping on these properties is also analyzed. It is\nseen that the band gap of the undoped compound narrowed with dopant\nconcentration which disappeared for x = 0.26 for Bi doping and 0.36 for Ta\ndoping. The materials thus become conductive oxides through the change in the\nelectronic properties of the compound for x \\leq 0.75 which may be useful for\npotential application. The calculated optical properties, e.g. dielectric\nfunction, refractive index, absorption spectrum, loss-function, reflectivity\nand conductivity of the undoped SnO2 in two polarization directions are\ncompared with both previous calculations and measurements.\n  Keywords: Doped SnO2; First-principles; Mechanical properties; Electronic\nband structure; Optical properties.",
        "positive": "High-throughput screening for Weyl Semimetals with S$_{4}$ Symmetry: Based on irreducible representations (or symmetry eigenvalues) and\ncompatibility relations, a material can be predicted to be a\ntopological/trivial insulator [satisfying compatibility relations] or a\ntopological semimetal [violating compatibility relations]. However, Weyl\nsemimetals usually go beyond this symmetry-based strategy. In other words, Weyl\nnodes could emerge in a material, no matter if its occupied bands satisfy\ncompatibility relations, or if the symmetry indicators are zero. In this work,\nwe propose a new topological invariant $\\chi$ for the systems with S$_4$\nsymmetry [i.e., the improper rotation S$_4$ ($\\equiv$ IC$_{4z}$) is a proper\nfour-fold rotation (C$_{4z}$) followed by inversion (I)], which can be used to\ndiagnose the Weyl semimetal phase. Moreover, $\\chi$ can be easily computed\nthrough the one-dimensional Wilson-loop technique. By applying this method to\nthe high-throughput screening in first-principles calculations, we predict a\nlot of Weyl semimetals in both nonmagnetic and magnetic compounds. Various\ninteresting properties (e.g. magnetic frustration effects, superconductivity\nand spin-glass order, etc.) are found in predicted Weyl semimetals, which\nprovide realistic platforms for future experimental study of the interplay\nbetween Weyl fermions and other exotic states."
    },
    {
        "anchor": "Diffusive versus displacive contact plasticity of nanoscale asperities:\n  Temperature- and velocity-dependent strongest size: We predict a strongest size for the contact strength when asperity radii of\ncurvature decrease below ten nanometers. The reason for such strongest size is\nfound to be correlated with the competition between the dislocation plasticity\nand surface diffusional plasticity. The essential role of temperature is\ncalculated and illustrated in a comprehensive asperity size-strengthtemperature\nmap taking into account the effect of contact velocity. Such a map should be\nessential for various phenomena related to nanoscale contacts such as nanowire\ncold welding, self-assembly of nanoparticles and adhesive nano-pillar arrays,\nas well as the electrical, thermal and mechanical properties of macroscopic\ninterfaces.",
        "positive": "Benchmarking theoretical electronic structure methods with photoemission\n  orbital tomography: In the past decade, photoemission orbital tomography (POT) has evolved into a\npowerful tool to investigate the electronic structure of organic molecules\nadsorbed on (metallic) surfaces. By measuring the angular distribution of\nphotoelectrons as a function of binding energy and making use of the\nmomentum-space signature of molecular orbitals, POT leads to an\norbital-resolved picture of the electronic density of states at the\norganic/metal interface. In this combined experimental and theoretical work, we\napply POT to the prototypical organic $\\pi$-conjugated molecule bisanthene\n(C$_{28}$H$_{14}$) which forms a highly oriented monolayer on a Cu(110)\nsurface. Experimentally, we identify an unprecedented number of 13 $\\pi$ and 12\n$\\sigma$ orbitals of bisanthene and measure their respective binding energies\nand spectral lineshapes at the bisanthene/Cu(110) interface. Theoretically, we\nperform density functional calculations for this interface employing four\nwidely used exchange-correlation functionals from the families of the\ngeneralized gradient approximations as well as global and range-separated\nhybrid functionals. By analyzing the electronic structure in terms of\norbital-projected density of states, we arrive at a detailed orbital-by-orbital\nassessment of theory vs. experiment. This allows us to benchmark the\nperformance of the investigated functionals with regards to their capability of\naccounting for the orbital energy alignment at organic/metal interfaces."
    },
    {
        "anchor": "Intermolecular coupling and fluxional behavior of hydrogen in phase IV: We performed Raman and infrared (IR) spectroscopy measurements of hydrogen at\n295 K up to 280 GPa at an IR synchrotron facility of SSRF. To reach the highest\npressure, hydrogen was loaded into toroidal diamond anvils with 40 micrometers\ncentral culet. The intermolecular coupling has been determined by concomitant\nmeasurements of the IR and Raman vibron modes. In phase IV, we find that the\nintermolecular coupling is much stronger in the graphene (G) like layer of\nelongated molecules compared to the Br2 like layer of shortened molecules and\nit increases with pressure much faster in the G layer compared to the Br2\nlayer. These heterogeneous lattice dynamical properties are unique features of\nhighly fluxional hydrogen phase IV.",
        "positive": "Scaling theory of magneto-resistance in disordered local moment\n  ferromagnets: We present a scaling theory of magneto-transport in Anderson-localized\ndisordered ferromagnets. Within our framework a pronounced\nmagnetic-field-sensitive resistance peak emerges naturally for temperatures\nnear the magnetic phase transition. We find that the resistance anomaly is a\ndirect consequence of the change in localization length caused by the magnetic\ntransition. For increasing values of the external magnetic field, the\nresistance peak is gradually depleted and pushed towards higher temperatures.\nOur results are in good agreement with magneto-resistance measurements on a\nvariety of disordered magnets."
    },
    {
        "anchor": "Quantum size effect in Pb(100) films: the role of symmetry and\n  implication for film growth: We show from density-functional calculations that Pb(100) thin films exhibit\nquantum size effect with a bilayer periodicity in film energies, film\nrelaxations, and work functions, which originate from different symmetry of the\nstacking geometry of odd and even layer films. The bilayer periodicity of the\nfilm energy is argued to survive on a semiconductor substrate, which should\nallow the growth of ``magically'' thick even-layer Pb(100) films. Furthermore,\nit is found that the quantum well states in a simple metal film can be\nclassified into $\\sigma$-bonded and $\\pi$-bonded states, which quantize\nindependently.",
        "positive": "Orthorhombic versus monoclinic symmetry of the charge-ordered state of\n  NaV2O5: High-resolution X-ray diffraction data show that the low-temperature\nsuperstructure of alpha-NaV2O5 has an F-centered orthorhombic 2a x 2b x 4c\nsuperlattice. A structure model is proposed, that is characterized by layers\nwith zigzag charge order on all ladders and stacking disorder, such that the\naveraged structure has space group Fmm2. This model is in accordance with both\nX-ray scattering and NMR data. Variations in the stacking order and disorder\noffer an explanation for the recently observed devils staircase of the\nsuperlattice period along c."
    },
    {
        "anchor": "Diameter and Chirality Dependence of Exciton Properties in Carbon\n  Nanotubes: We calculate the diameter and chirality dependences of the binding energies,\nsizes, and bright-dark splittings of excitons in semiconducting single-wall\ncarbon nanotubes (SWNTs). Using results and insights from {\\it ab initio}\ncalculations, we employ a symmetry-based, variational method based on the\neffective-mass and envelope-function approximations using tight-binding\nwavefunctions. Binding energies and spatial extents show a leading dependence\nwith diameter as $1/d$ and $d$, respectively, with chirality corrections\nproviding a spread of roughly 20% with a strong family behavior. Bright-dark\nexciton splittings show a $1/d^2$ leading dependence. We provide analytical\nexpressions for the binding energies, sizes, and splittings that should be\nuseful to guide future experiments.",
        "positive": "Long-range Effect on the Curie Temperature of Ferroelectric Films: In this paper, the Curie temperature of ferroelectric films is studied using\nspin-1/2 transverse Ising model with long-range interaction within the\nframework of the effective-field theory. The dependence of the Curie\ntemperature on the thickness of the film, the surface interaction and the\ntransverse field were investigated. It is assumed that the long-range\ninteraction decays with the distance between the pseudo-spins as a power law.\nThe dependence of the Curie temperature and the critical transverse field on\nthe long-range exponent are obtained."
    },
    {
        "anchor": "Bias dependence of perpendicular spin torque and of free and fixed layer\n  eigenmodes in MgO-based nanopillars: We have measured the bias voltage and field dependence of eigenmode\nfrequencies in a magnetic tunnel junction with MgO barrier. We show that both\nfree layer (FL) and reference layer (RL) modes are excited, and that a\ncross-over between these modes is observed by varying external field and bias\nvoltage. The bias voltage dependence of the FL and RL modes are shown to be\ndramatically different. The bias dependence of the FL modes is linear in bias\nvoltage, whereas that of the RL mode is strongly quadratic. Using modeling and\nmicromagnetic simulations, we show that the linear bias dependence of FL\nfrequencies is primarily due to a linear dependence of the perpendicular spin\ntorque on bias voltage, whereas the quadratic dependence of the RL on bias\nvoltage is dominated by the reduction of exchange bias due to Joule heating,\nand is not attributable to a quadratic dependence of the perpendicular spin\ntorque on bias voltage.",
        "positive": "Effects of C and B microalloying additions on the microstructure and\n  processability of Ren\u00e9 41 Ni-based superalloy: Ren\\'e 41 is a cast and wrought Ni-based superalloy with high yield strength\nand stress-rupture properties contrasted with poor processability. The aim of\nthis thesis is to systematically investigate the influence of C and B\nmicroalloying additions on processability of Ren\\'e 41. The first approach is\nan experimental one using hot compression testing and material\ncharacterisation. A second approach using machine learning methodology was also\nused to provide linkage for the experimental observations with industrial\nRen\\'e 41 materials based on ultrasonic defects and chemical composition. Three\nRen\\'e 41 variants with nominal, high C, and high B compositions were\nindustrially fabricated and homogenized to be used in this study. The resultant\nflow stresses from hot compression testing were used to model hyperbolic sine\nconstitutive equations. The activation energy for hot deformation was found to\nbe 757, 728, and 697 kJmol-1 for the nominal, high B, and high C Ren\\'e 41\nvariants respectively. Finite element method simulations based on the obtained\nflow curves found that effective plastic strain varied considerably through the\nsample geometry. Quantitative analysis via electron back-scatted diffraction\nfound that while the three Ren\\'e 41 variants have nearly identical\nrecrystallised grain size, high C contain 64 vol.% recrystallised fractions\ncompared to that of the nominal variant with 31 vol.% at the same deformation\ncondition."
    },
    {
        "anchor": "Tailoring magnetic insulator proximity effects in graphene:\n  First-principles calculations: We report a systematic first-principles investigation of the influence of\ndifferent magnetic insulators on the magnetic proximity effect induced in\ngraphene. Four different magnetic insulators are considered: two ferromagnetic\neuropium chalcogenides namely EuO and EuS and two ferrimagnetic insulators\nyttrium iron garnet (YIG) and cobalt ferrite (CFO). The obtained\nexchange-splitting varies from tens to hundreds of meV. We also find an\nelectron doping induced by YIG and europium chalcogenides substrates, that\nshift the Fermi level up to 0.78 eV and 1.3 eV respectively, whereas hole\ndoping up to 0.5 eV is generated by CFO. Furthermore, we study the variation of\nthe extracted exchange and tight binding parameters as a function of the EuO\nand EuS thicknesses. We show that those parameters are robust to thickness\nvariation such that a single monolayer of magnetic insulator can induce a large\nmagnetic proximity effect on graphene. Those findings pave the way towards\npossible engineering of graphene spin-gating by proximity effect especially in\nview of recent experiments advancement.",
        "positive": "Mitsui model with diagonal strains: A unified description of external\n  pressure effect and thermal expansion of Rochelle salt NaKC_4H_4O_6\\cdot4H_2O: We elaborate a modification of the deformable two-sublattice Mitsui model of\n[Levitskii R.R. et al., Phys. Rev. B. 2003, 67, 174112] and [Levitskii R.R. et\nal., Condens. Matter Phys., 2005, 8, 881] that consistently takes into account\ndiagonal components of the strain tensor, arising either due to external\npressures or due to thermal expansion. We calculate the related to those\nstrains thermal, piezoelectric, and elastic characteristics of the system.\nUsing the developed fitting procedure, a set of the model parameters is found\nfor the case of Rochelle salt crystals, providing a satisfactory agreement with\nthe available experimental data for the hydrostatic and uniaxial pressure\ndependences of the Curie temperatures, temperature dependences of spontaneous\ndiagonal strains, linear thermal expansion coefficients, elastic constants\nc_ij^E and c_i4^E, piezoelectric coefficients d_1i and g_1i (i=1,2,3). The\nhydrostatic pressure variation of dielectric permittivity is described using a\nderived expression for the permittivity of a partially clamped crystal. The\ndipole moments and the asymmetry parameter of Rochelle salt are found to\nincrease with hydrostatic pressure."
    },
    {
        "anchor": "Origin of spectral purity and tuning sensitivity in a vortex-based spin\n  transfer nano-oscillator: We investigate the microwave characteristics of a spin transfer\nnano-oscillator (STNO) based on coupled vortices as a function of the\nperpendicular magnetic field $H_\\perp$. While the generation linewidth displays\nstrong variations on $H_\\perp$ (from 40 kHz to 1 MHz), the frequency tunability\nin current remains almost constant (~7 MHz/mA). We demonstrate that our\nvortex-based oscillator is quasi-isochronous independently of $H_\\perp$, so\nthat the severe nonlinear broadening usually observed in STNOs does not exist.\nInterestingly, this does not imply a loss of frequency tunability, which is\nhere governed by the current induced Oersted field. Nevertheless this is not\nsufficient to achieve the highest spectral purity in the full range of\n$H_\\perp$ either: we show that the observed linewidth broadenings are due to\nthe excited mode interacting with a lower energy overdamped mode, which occurs\nat the successive crossings between harmonics of these two modes. These\nfindings open new possibilities for the design of STNOs and the optimization of\ntheir performance.",
        "positive": "Monte Carlo Study of the Crystalline and Amorphous NaK Alloy: Metropolis Monte Carlo simulations of the eutectic NaK alloy are performed\nusing the Second Moment Approximation (SMA) model potential across a wide range\nof temperatures at constant pressure. The alloy structure and thermodynamics\nare analyzed along with the atomic level structures using a variety of\nstructure identification methods. Both enthalpy and density are followed along\nan annealing process that reveals a clear melting point around 250 K. At lower\ntemperatures, two thermodynamic branches are identified as crystalline and\namorphous solids."
    },
    {
        "anchor": "Graphene-Graphite Quilts for Thermal Management of High-Power GaN\n  Transistors: Self-heating is a severe problem for high-power GaN electronic and\noptoelectronic devices. Various thermal management solutions, e.g. flip-chip\nbonding or composite substrates have been attempted. However, temperature rise\nstill limits applications of the nitride-based technology. Here we demonstrate\nthat thermal management of GaN transistors can be substantially improved via\nintroduction of the alternative heat-escaping channels implemented with\nfew-layer graphene - an excellent heat conductor. We have transferred few-layer\ngraphene to AlGaN/GaN heterostructure field-effect transistors on SiC\nsubstrates to form the \"graphene-graphite quilts\" - lateral heat spreaders,\nwhich remove heat from the channel regions. Using the micro-Raman spectroscopy\nfor in-situ monitoring we have shown that temperature can be lowered by as much\nas ~ 20oC in such devices operating at ~13-W/mm power density. The simulations\nsuggest that the efficiency of the \"graphene quilts\" can be made even higher in\nGaN devices on thermally resistive sapphire substrates and in the designs with\nthe closely located heat sinks. Our results open a novel application niche for\nfew-layer graphene in high-power electronics.",
        "positive": "Artifacts in magnetic spirals retrieved by transport of intensity\n  equation (TIE): The artifacts in the magnetic structures reconstructed from Lorentz\ntransmission electron microscopy (LTEM) images with TIE method have been\nanalyzed in detail. The processing for the simulated images of Bloch and Neel\nspirals indicated that the improper parameters in TIE may overestimate the high\nfrequency information and induce some false features in the retrieved images.\nThe specimen tilting will further complicate the analysis of the images because\nthe LTEM image contrast is not the result of the magnetization distribution\nwithin the specimen but the integral projection pattern of the magnetic\ninduction filling the entire space including the specimen."
    },
    {
        "anchor": "Semiconductor quantum tubes: dielectric modulation and excitonic\n  response: We study theoretically the optical properties of quantum tubes,\none-dimensional semiconductor nanostructures where electrons and holes are\nconfined to a cylindrical shell. In these structures, which bridge between 2D\nand 1D systems, the electron-hole interaction may be modulated by a dielectric\nsubstance outside the quantum tube and possibly inside its core. We use the\nexact Green's function for the appropriate dielectric configuration and exact\ndiagonalization of the electron-hole interaction within an effective mass\ndescription to predict the evolution of the exciton binding energy and\noscillator strength. Contrary to the homogeneous case, in dielectrically\nmodulated tubes the exciton binding is a function of the tube diameter and can\nbe tuned to a large extent by structure design and proper choice of the\ndielectric media.",
        "positive": "Extrinsic Anomalous Hall effect in Mn Doped GeSnTe Semiconductors in the\n  Bad Metal Hopping Regime: We present high field magnetotransport studies of Ge1-x-y(SnxMny)Te bulk\nmultiferroics with diamagnetic Sn and paramagnetic Mn concentration x = 0.38 to\n0.79 and y = 0.02 to 0.086, respectively. The zero field resistivity, {\\rho}(T)\ntakes significant contribution from defects below T = 20 K however, a mixed\nscattering contribution from dynamic disorder and unusual sources is estimated\nfrom T = 20 K to 300 K. The carrier mobility shows anomalous temperature\ndependence from T0.2 to T0.5 which hints towards possible presence of polaronic\neffects resulting from coupling of holes with phonons. This anomalous behavior\ncannot be understood in terms of pure phononic scattering mechanism at high\ntemperature. From point of view of high field results, the transverse component\nof magnetoresistivity manifests anomalous Hall effect originating from\nextrinsic scattering sources, particularly the side jump mechanism reveals a\nlarger contribution. We also find that the correlation between the transverse\nand longitudinal conductivities follow the universal scaling law {\\sigma}xy ~\n{\\sigma}xxn where n = 1.6 in the low conductivity limit. The values n = 1.5 to\n1.8 obtained for the present GSMT alloys justify the bad metal hopping regime\nsince the results fall in the low conductivity ferromagnetic family with\n{\\sigma}xx ~ 104 ohmcm-1. The interpretation of the n = 1.6 scaling in the low\nconductivity regime is thus far not fully understood. However, the anomalous\nHall resistivity scaling with modified relation by Tian et al is indicative of\nthe dominant side jump scattering along with noticeable role of skew\nscattering."
    },
    {
        "anchor": "2D magnetoelectric multiferroics in MnSTe/In2Se3 heterobilayer with\n  ferroelectrically controllable skyrmions: The magnetoelectric effect and skyrmions are two fundamental phenomena in the\nfield of condensed-matter physics. Here, using first-principles calculations\nand Monte-Carlo simulations, we propose that strong magnetoelectric coupling\ncan be demonstrated in a multiferroic heterobilayer consisting of\ntwo-dimensional (2D) MnSTe and {\\alpha}-In2Se3. As the electric polarization in\nferroelectric {\\alpha}-In2Se3 is switched, the creation and annihilation of\ntopological magnetic phase can be achieved in this multiferroic heterobilayer,\ngiving rise to the intriguing ferroelectrically controllable skyrmions. This\nfeature is further revealed to be closely related to the physical quantity of\nD2/|KJ|, which is generally applicable for describing the required conditions\nof such physics. Moreover, the evaluations of their topological magnetic phases\nwith temperature are systematically discussed. These insights not only greatly\nenrich the research on 2D magnetoelectric multiferroics, but also pave a\npromising avenue to realize new skyrmionic device concepts.",
        "positive": "Alternating-spin-chain compound AgVOAsO$_4$ probed by $^{75}$As NMR: $^{75}$As NMR measurements were performed on a polycrystalline sample of\nspin-1/2 alternating-spin-chain Heisenberg antiferromagnet AgVOAsO$_4$.\nTemperature-dependent NMR shift $K(T)$, which is a direct measure of the\nintrinsic spin susceptibility, agrees very well with the spin-1/2\nalternating-chain model, justifying the assignment of the spin lattice. From\nthe analysis of $K(T)$, magnetic exchange parameters were estimated as follows:\nthe leading exchange $J/k_{\\rm B} \\simeq 38.4$ K, alternation ratio $\\alpha =\nJ'/J \\simeq 0.68$, and spin gap $\\Delta/k_{\\rm B} \\simeq 15$ K. The transferred\nhyperfine coupling between the $^{75}$As nucleus and V$^{4+}$ spins obtained by\ncomparing the NMR shift with bulk susceptibility amounts to $A_{\\rm hf} \\simeq\n3.3$ T/$\\mu_{\\rm B}$. Our temperature-dependent spin-lattice relaxation rate\n$1/T_1(T)$ also shows an activated behaviour at low temperatures, thus\nconfirming the presence of a spin gap in AgVOAsO$_4$."
    },
    {
        "anchor": "Hydrogen in Disordered Titania: Connecting Local Chemistry, Structure,\n  and Stoichiometry through Accelerated Exploration: Hydrogen incorporation in native surface oxides of metal alloys often\ncontrols the onset of metal hydriding, with implications for materials\ncorrosion and hydrogen storage. A key representative example is titania, which\nforms as a passivating layer on a variety of titanium alloys for structural and\nfunctional applications. These oxides tend to be structurally diverse,\nfeaturing polymorphic phases, grain boundaries, and amorphous regions that\ngenerate a disparate set of unique local environments for hydrogen. Here, we\nintroduce a workflow that can efficiently and accurately navigate this\ncomplexity. First, a machine learning force field, trained on ab initio\nmolecular dynamics simulations, was used to generate amorphous configurations.\nDensity functional theory calculations were then performed on these structures\nto identify local oxygen environments, which were compared against experimental\nobservations. Second, to classify subtle differences across the disordered\nconfiguration space, we employ a graph-based sampling procedure. Finally, local\nhydrogen binding energies are computed using exhaustive density functional\ntheory calculations on representative configurations. We leverage this\nmethodology to show that hydrogen binding energetics are described by local\noxygen coordination, which in turn is affected by stoichiometry. Together these\nresults imply that hydrogen incorporation and transport in TiO$_x$ can be\ntailored through compositional engineering, with implications for improving\nperformance and durability of titanium-derived alloys in hydrogen environments.",
        "positive": "Magnetoelectrically driven catalytic degradation of organics: Here, we report the catalytic degradation of organic compounds by exploiting\nthe magnetoelectric (ME) nature of cobalt ferrite-bismuth ferrite (CFO-BFO)\ncore-shell nanoparticles. The combination of magnetostrictive CFO with the\nmultiferroic BFO gives rise to a magnetoelectric engine that purifies water\nunder wireless magnetic fields via advanced oxidation processes, without\ninvolvement of any sacrificial molecules or co-catalysts. Magnetostrictive\nCoFe2O4 nanoparticles are fabricated using hydrothermal synthesis, followed by\nsol-gel synthesis to create the multiferroic BiFeO3 shell. We perform\ntheoretical modeling to study the magnetic field induced polarization on the\nsurface of magnetoelectric nanoparticles. The results obtained from these\nsimulations are consistent with the experimental findings of the piezo-force\nmicroscopy analysis, where we observe changes in the piezoresponse of the\nnanoparticles under magnetic fields. Next, we investigate the magnetoelectric\neffect induced catalytic degradation of organic pollutants under AC magnetic\nfields and obtained 97% removal efficiency for synthetic dyes and over 85%\nremoval efficiency for routinely used pharmaceuticals. Additionally, we perform\ntrapping experiments to elucidate the mechanism behind the magnetic field\ninduced catalytic degradation of organic pollutants by using scavengers for\neach of the reactive species. Our results indicate that hydroxyl and superoxide\nradicals are the main reactive species in the magnetoelectrically induced\ncatalytic degradation of organic compounds."
    },
    {
        "anchor": "Machine learning driven synthesis of few-layered WTe2: Reducing the lateral scale of two-dimensional (2D) materials to\none-dimensional (1D) has attracted substantial research interest not only to\nachieve competitive electronic device applications but also for the exploration\nof fundamental physical properties. Controllable synthesis of high-quality 1D\nnanoribbons (NRs) is thus highly desirable and essential for the further study.\nTraditional exploration of the optimal synthesis conditions of novel materials\nis based on the trial-and-error approach, which is time consuming, costly and\nlaborious. Recently, machine learning (ML) has demonstrated promising\ncapability in guiding material synthesis through effectively learning from the\npast data and then making recommendations. Here, we report the implementation\nof supervised ML for the chemical vapor deposition (CVD) synthesis of\nhigh-quality 1D few-layered WTe2 nanoribbons (NRs). The synthesis parameters of\nthe WTe2 NRs are optimized by the trained ML model. On top of that, the growth\nmechanism of as-synthesized 1T' few-layered WTe2 NRs is further proposed, which\nmay inspire the growth strategies for other 1D nanostructures. Our findings\nsuggest that ML is a powerful and efficient approach to aid the synthesis of 1D\nnanostructures, opening up new opportunities for intelligent material\ndevelopment.",
        "positive": "Data-Driven Electron Microscopy: Electron Diffraction Imaging of\n  Materials Structural Properties: Transmission electron diffraction is a powerful and versatile structural\nprobe for the characterization of a broad range of materials, from\nnanocrystalline thin films to single crystals. With recent developments in fast\nelectron detectors and efficient computer algorithms, it now becomes possible\nto collect unprecedently large datasets of diffraction patterns (DPs) and\nprocess DPs to extract crystallographic information to form images or tomograms\nbased on crystal structural properties, giving rise to data-driven electron\nmicroscopy. Critical to this kind of imaging is the type of crystallographic\ninformation being collected, which can be achieved with a judicious choice of\nelectron diffraction techniques, and the efficiency and accuracy of DP\nprocessing, which requires the development of new algorithms. Here, we review\nrecent progress made in data collection, new algorithms, and automated electron\nDP analysis. These progresses will be highlighted using application examples in\nmaterials research. Future opportunities based on smart sampling and machine\nlearning are also discussed."
    },
    {
        "anchor": "Engineering Dion-Jacobson Perovskites in Polariton Waveguides: Hybrid two-dimensional perovskites hold considerable promise as\nsemiconductors for a wide range of optoelectronic applications. Many efforts\nare addressed to exploit the potential of these materials by tailoring their\ncharacteristics. In this work, the optical properties and electronic band\nstructure in three new Dion-Jacobson (DJ) perovskites (PVKs) are engineered by\nmodulating their structural distortion. Two different interlayer cations: 1-6,\nHexamethylendiammonium, HE, and 3-(Dimethylamino)-1-propylammonium, DMPA, have\nbeen selected to investigate the role of the cation length and the ammonium\nbinding group on the crystalline structure. This study provides new insights\ninto the understanding of the structure-property relationship in DJ perovskites\nand demonstrates that exciton characteristics can be easily modulated with the\njudicious design of the organic cations. DJ PVKs developed in this work were\nalso grown as size-controlled single crystal microwires through a\nmicrofluidic-assisted synthesis technique and integrated in a nanophotonic\ndevice. The DJ PVK microwire acts as a waveguide exhibiting strong light-matter\ncoupling between the crystal optical modes and DJ PVK exciton. Through the\ninvestigation of these polariton waveguides, the nature of the double peak\nemission, which is often observed in these materials and whose nature is\nlargely debated in the literature, is demonstrated originating from the hybrid\npolariton state.",
        "positive": "Electric-field control of the magnetic anisotropy in an ultrathin\n  (Ga,Mn)As/(Ga,Mn)(As,P) bilayer: We report on the electric control of the magnetic anisotropy in an ultrathin\nferromagnetic (Ga,Mn)As/(Ga,Mn)(As,P) bilayer with competing in-plane and\nout-of-plane anisotropies. The carrier distribution and therefore the strength\nof the effective anisotropy is controlled by the gate voltage of a field effect\ndevice. Anomalous Hall Effect measurements confirm that a depletion of carriers\nin the upper (Ga,Mn)As layer results in the decrease of the in-plane\nanisotropy. The uniaxial anisotropy field is found to decrease by a factor ~ 4\nover the explored gate-voltage range, so that the transition to an out-of-plane\neasy-axis configuration is almost reached."
    },
    {
        "anchor": "Intertwined Rashba, Dirac and Weyl Fermions in Hexagonal\n  Hyperferroelectrics: By means of density functional theory based calculations, we study the role\nof spin-orbit coupling in the new family of ABC hyperferroelectrics [Phys. Rev.\nLett. 112, 127601 (2014)]. We unveil an extremely rich physics strongly linked\nto ferroelectric properties, ranging from the electric control of bulk Rashba\neffect to the existence of a three dimensional topological insulator phase,\nwith concomitant topological surface states even in the ultrathin film limit.\nMoreover, we predict that the topological transition, as induced by alloying,\nis followed by a Weyl semi-metal phase of finite concentration extension, which\nis robust against disorder, putting forward hyperferroelectrics as promising\ncandidates for spin-orbitronic applications.",
        "positive": "Note on Spin Structure of the Classical Vector Spin Heisenberg Model: A comment on Yoshimori's helical spin structure theory."
    },
    {
        "anchor": "Stochastic approaches: modeling the probability of encounters between\n  H$_{2}$-molecules and metallic atomic clusters in a cubic box: In recent years the advance of chemical synthesis has made it possible to\nobtain \\textquotedblleft naked\\textquotedblright clusters of different\ntransition metals. It is well known that cluster experiments allow studying the\nfundamental reactive behavior of catalytic materials in an environment that\navoids the complications present in extended solid-phase research. In\nphysicochemical terms, the question that arises is the chemical reduction of\nmetallic clusters could be affected by the presence of H$_{_{2}}$ molecules,\nthat is, by the probability of encounter that these small metal atomic\nagglomerates can have with these reducing species. Therefore, we consider the\nstochastic movement of $N$ molecules of hydrogen in a cubic box containing $M$\nmetallic atomic clusters in a confined region of the box. We use a Wiener\nprocess to simulate the stochastic process, with $\\sigma$ given by the\nMaxwell-Boltzmann relationships, which enabled us to obtain an analytical\nexpression for the probability density function. This expression is an exact\nexpression, obtained under an original proposal outlined in this work,\n\\textit{i.e.} obtained from considerations of \\textit{mathematical rebounds}.\nOn this basis, we obtained the probability of encounter for three different\nvolumes, $0.1^{^{3}}$, $ 0.2^{^{3}} $ and $ 0.4^{^{3}} $ m$^{^{3}}$, at three\ndifferent temperatures in each case, $293$, $373$ and $473$ K, for $\n10^{^{1}}\\leq N \\leq10^{^{10}}$, comparing the results with those obtained\nconsidering the distribution of the position as a Truncated Normal\nDistribution. Finally, we observe that the probability is significantly\naffected by the number $N$ of molecules and by the size of the box, not by the\ntemperature.",
        "positive": "Anamolous reduction of magnetic coercivity of graphene oxide and reduced\n  graphene oxide upon cooling: In this report we present the temperature evolution of magnetic coercivity of\ngraphene oxide (GO) and reduced graphene oxide (RGO). We report an anamolous\ndecrease in coercivity of GO and RGO with decreasing temperature. We could\nexplain this anamolous behavior invoking the inherent presence of ripple in\ngraphene. We observe antiferromagnetic and ferromagnetic behavior at room\ntemperature for GO and RGO respectively, but at low temperatures both shows\nparamagnetic behavior."
    },
    {
        "anchor": "Near-field scanning microwave microscope for interline capacitance\n  characterization of nanoelectronics interconnect: We have developed a noncontact method for measurement of the interline\ncapacitance in Cu/low-k interconnect. It is based on a miniature test vehicle\nwith net capacitance of a few femto-Farads formed by two 20-\\mu m-long parallel\nwires (lines) with widths and spacings the same as those of the interconnect\nwires of interest. Each line is connected to a small test pad. The vehicle\nimpedance is measured at 4 GHz by a near-field microwave probe with 10 \\mu m\nprobe size via capacitive coupling of the probe to the vehicle's test pads.\nFull 3D finite element modeling at 4 GHz confirms that the microwave radiation\nis concentrated between the two wires forming the vehicle. An analytical lumped\nelement model and a short/open calibration approach have been proposed to\nextract the interline capacitance value from the measured data. We have\nvalidated the technique on several test vehicles made with copper and low-k\ndielectric on a 300 mm wafer. The vehicles interline spacing ranges from 0.09\nto 1 \\mu m and a copper line width is 0.15 \\mu m. This is the first time a\nnear-field scanning microwave microscope has been applied to measure the lumped\nelement impedance of a test vehicle.",
        "positive": "Optical Properties of BN in the cubic and in the layered hexagonal\n  phases: Linear optical functions of cubic and hexagonal BN have been studied within\nfirst principles DFT-LDA theory. Calculated energy-loss functions compare well\nwith experiments and previous theoretical results both for h-BN and for c-BN.\nDiscrepancies arise between theoretical results and experiments in the\nimaginary part of the dielectric function for c-BN. Possible explanation to\nthis mismatch are proposed and evaluated; lattice constant variations, h-BN\ncontamination in c-BN samples and self-energy effects."
    },
    {
        "anchor": "Crystal Structure of Silver Pentazolates AgN5 and AgN6: Silver pentazolate, a high energy density compound containing cyclo-N5-\nanion, has recently been synthesized at ambient conditions. However, due to\nhigh sensitivity to irradiation, its crystal structure has not been determined.\nIn this work, silver-nitrogen crystalline compounds at ambient conditions and\nhigh pressures, up to 100 GPa, are predicted and characterized by performing\nfirst-principles evolutionary crystal structure searching with variable\nstoichiometry. It is found that newly discovered AgN5 and AgN6 are the only\nthermodynamically stable silver-nitrogen compounds at pressures between 42 and\n80 GPa. In contrast to AgN5, pentazolate AgN6 compound contains N2 diatomic\nmolecules in addition to cyclo-N5-. These AgN5 and AgN6 crystals are metastable\nat ambient conditions with positive formation enthalpies of 54.95 kJ/mol and\n46.24 kJ/mol, respectively. The underlying cause of the stability of cyclo-N5-\nsilver pentazolates is the enhanced aromaticity enabled by the charge transfer\nfrom silver atoms to nitrogen rings. To aid in experimental identification of\nthese materials, calculated Raman spectra are reported at ambient pressure: the\nfrequencies of N5- vibrational modes of AgN5 are in good agreement with those\nmeasured in experiment.",
        "positive": "Reversible Basal Plane Hydrogenation of Graphene: We report the chemical reaction of single-layer graphene with hydrogen atoms,\ngenerated in situ by electron-induced dissociation of hydrogen silsesquioxane\n(HSQ). Hydrogenation, forming sp3 C-H functionality on the basal plane of\ngraphene, proceeds at a higher rate for single than for double layers,\ndemonstrating the enhanced chemical reactivity of single sheet graphene. The\nnet H atom sticking probability on single layers at 300 K is at least 0.03,\nwhich exceeds that of double layers by at least a factor of 15. Chemisorbed\nhydrogen atoms, which give rise to a prominent Raman D band, can be detached by\nthermal annealing at 100~200 degrees C. The resulting dehydrogenated graphene\nis \"activated\" when photothermally heated it reversibly binds ambient oxygen,\nleading to hole doping of the graphene. This functionalization of graphene can\nbe exploited to manipulate electronic and charge transport properties of\ngraphene devices."
    },
    {
        "anchor": "Soliton effects in dangling-bond wires on Si(001): Dangling bond wires on Si(001) are prototypical one dimensional wires, which\nare expected to show polaronic and solitonic effects. We present electronic\nstructure calculations, using the tight binding model, of solitons in\ndangling-bond wires, and demonstrate that these defects are stable in\neven-length wires, although approximately 0.1 eV higher in energy than a\nperfect wire. We also note that in contrast to conjugated polymer systems,\nthere are two types of soliton and that the type of soliton has strong effects\non the energetics of the bandgap edges, with formation of intra-gap states\nbetween 0.1 eV and 0.2 eV from the band edges. These intra-gap states are\nlocalised on the atoms comprising the soliton.",
        "positive": "Coulomb interactions in single, charged self-assembled quantum dots:\n  radiative lifetime and recombination energy: We present results on the charge dependence of the radiative recombination\nlifetime, Tau, and the emission energy of excitons confined to single\nself-assembled InGaAs quantum dots. There are significant dot-to-dot\nfluctuations in the lifetimes for a particular emission energy. To reach\ngeneral conclusions, we present the statistical behavior by analyzing data\nrecorded on a large number of individual quantum dots. Exciton charge is\ncontrolled with extremely high fidelity through an n-type field effect\nstructure, providing access to the neutral exciton (X0), the biexciton (2X0)\nand the positively (X1+) and negatively (X1-) charged excitons. We find\nsignificant differences in the recombination lifetime of each exciton such\nthat, on average, Tau(X1-) / Tau(X0) = 1.25, Tau(X1+) / Tau(X0) = 1.58 and\nTau(2X0) / Tau(X0) = 0.65. We attribute the change in lifetime to significant\nchanges in the single particle hole wave function on charging the dot, an\neffect more pronounced on charging X0 with a single hole than with a single\nelectron. We verify this interpretation by recasting the experimental data on\nexciton energies in terms of Coulomb energies. We show directly that the\nelectron-hole Coulomb energy is charge dependent, reducing in value by 5-10% in\nthe presence of an additional electron, and that the electron-electron and\nhole-hole Coulomb energies are almost equal."
    },
    {
        "anchor": "High-energy spectroscopic study of the III-V nitride-based diluted\n  magnetic semiconductor Ga$_{1-x}$Mn$_{x}$N: We have studied the electronic structure of the diluted magnetic\nsemiconductor Ga$_{1-x}$Mn$_{x}$N ($x$ = 0.0, 0.02 and 0.042) grown on Sn-doped\n$n$-type GaN using photoemission and soft x-ray absorption spectroscopy. Mn\n$L$-edge x-ray absorption have indicated that the Mn ions are in the\ntetrahedral crystal field and that their valence is divalent. Upon Mn doping\ninto GaN, new state were found to form within the band gap of GaN, and the\nFermi level was shifted downward. Satellite structures in the Mn 2$p$ core\nlevel and the Mn 3$d$ partial density of states were analyzed using\nconfiguration-interaction calculation on a MnN$_{4}$ cluster model. The deduced\nelectronic structure parameters reveal that the $p$-$d$ exchange coupling in\nGa$_{1-x}$Mn$_{x}$N is stronger than that in Ga$_{1-x}$Mn$_{x}$As.",
        "positive": "Optimization of epitaxial graphene growth for quantum metrology: (See the complete abstract within the thesis in both English and German\nversions)\n  In this thesis, the process conditions of the epitaxial graphene growth\nthrough a socalled polymer-assisted sublimation growth method are minutely\ninvestigated. Atomic force microscopy (AFM) is used to show that the previously\nneglected flow-rate of the argon process gas has a significant influence on the\nmorphology of the SiC substrate and atop carbon layers. The results can be well\nexplained using a simple model for the thermodynamic conditions at the layer\nadjacent to the surface. The resulting control option of step-bunching on the\nsub-nanometer scales is used to produce the ultra-flat, monolayer graphene\nlayers without the bilayer inclusions that exhibit the vanishing of the\nresistance anisotropy. The comparison of four-point and scanning tunneling\npotentiometry measurements shows that the remaining small anisotropy represents\nthe ultimate limit, which is given solely by the remaining resistances at the\nSiC terrace steps. ... The precise control of step-bunching using the Ar flow\nalso enables the preparation of periodic non-identical SiC surfaces under the\ngraphene layer. Based on the work function measurements by Kelvin-Probe force\nmicroscopy and X-ray photoemission electron microscopy, it is shown for the\nfirst time that there is a doping variation in graphene, induced by a proximity\neffect of the different near-surface SiC stacks. The comparison of the AFM and\nlow-energy electron microscopy measurements have enabled the exact assignment\nof the SiC stacks, and the examinations have led to an improved understanding\nof the surface restructuring in the framework of a step-flow mode. ..."
    },
    {
        "anchor": "Absence of first order magnetic transition, a curious case of Mn3InC: The volume expanding magnetostructural transition in Mn$_3$GaC and Mn$_3$SnC\nhas been identified to be due to distortion of Mn$_6$C octahedra. Despite a\nsimilar lattice volume as Mn$_3$SnC and similar valence electron contribution\nto the density of states as in Mn$_3$GaC, Mn$_3$InC does not undergo a first\norder magnetostructural transformation like the Ga and Sn antiperovskite\ncounterparts. A systematic investigation of its structure and magnetic\nproperties using probes like x-ray diffraction, magnetization measurements,\nneutron diffraction and extended x-ray absorption fine structure (EXAFS) reveal\nthat though the octahedra are distorted resulting in long and short Mn -- Mn\nbonds and different magnetic moments on Mn atoms, the interaction between them\nremains ferromagnetic. This has been attributed to the strain on the Mn$_6$C\noctahedra produced due to the relatively larger size of In atom compared to Sn\nand Ga. The size of In atom constricts the deformation of Mn$_6$C octahedra\ngiving rise to Mn -- Mn distances that favor only ferromagnetic interactions in\nthe compound.",
        "positive": "Spintronics in semiconductors: For the last years spin effects in semiconductors have been of great interest\nnot only in the context of solid state physics, but also for their potential\nusage in technology. In this paper we give a short review of spintronic\nmaterials, in which electron spin as an additional degree of freedom is\nexploited. Afterwards, we discuss the properties of classic, non-magnetic\nsemiconductors, where the efforts are put on enriching the traditional\nsemiconductor technology engaging the electrical effects of spin effects.\nVarious phenomena and scientific state of the art is highlighted."
    },
    {
        "anchor": "Role of matrix elements in the time-resolved photoemission signal: Time- and angle-resolved photoemission spectroscopy accesses the ultrafast\nevolution of quasiparticles and many-body interactions in solid-state systems.\nHowever, the momentum- and energy-resolved transient photoemission intensity\nmay not be unambiguously related to the intrinsic relaxation dynamics of\nphotoexcited electrons. In fact, interpretation of the time-dependent\nphotoemission signal can be affected by the transient evolution of both the\none-electron removal spectral function as well as the photoemission dipole\nmatrix elements. Here we investigate the topological insulator\nBi$_{1.1}$Sb$_{0.9}$Te$_2$S to demonstrate, by means of a careful\nprobe-polarization study, the transient contribution of matrix elements to the\ntime-resolved photoemission signal.",
        "positive": "Impact of 700keV Ni++ ion irradiation on structural and optical\n  properties of GaN: In this paper, we present the effects of high-energy Ni++ ion irradiation on\nthe structural and optical properties of GaN films. Three different irradiation\ndoses of 1013, 1014, and 1015 ions/cm2 were used while keeping the ion energy\nat 700keV. The irradiation induced structural and optical changes in GaN films\nwere measured using X-ray diffraction (XRD) and UV-Vis spectroscopy. The XRD\nmeasurements on irradiated films discovered several extra peaks in the XRD\nspectrum compared with the as-grown GaN film indicating the formation of new\nphases or defects in the GaN film due to the ion irradiation. The intensity of\nthese extra peaks increases with increasing ion dose, suggesting that the\ndensity of defects in the GaN film also increases with increasing ion dosage.\nThe UV-Vis measurements revealed a decrease in the bandgap of the irradiated\nGaN films from 3.40 eV for the pristine GaN film to 3.26 eV for the film\nirradiated with highest dose of 1015 ions/cm2. The decrease in bandgap can be\nattributed to the creation of defects and/or the formation of new phases in the\nGaN film due to the ion irradiation."
    },
    {
        "anchor": "Formation of metallic nano-crystals from gel-like precursor films for\n  CVD nanotube growth: An in-situ TEM characterization: The evolution of a continuous Fe(NO3)3 catalyst film was observed by in-situ\nannealing in a Transmission Electron Microscope (TEM). Such catalysts are\nroutinely used in the catalytic growth of carbon nanotubes. The experiments\nreveal that crystalline particles form from the gel-like film already around\n300C. At usual carbon nanotube growth temperatures of 700C, the particles are\nsingle-crystalline with a log-normal size distribution. The observations\nfurthermore show that in spite of the crystalline structure of the particles\nthere is a high mobility. The experiments allow to obtain detailed information\nabout the chemistry and the crystallinity of the catalyst film, which provides\nvaluable information for the interpretation of the carbon nanotube growth by\nchemical vapor deposition.",
        "positive": "Novel Orientational Ordering and Reentrant Metallicity in KxC60\n  Monolayers for 3 <= x <= 5: We have performed local STM studies on potassium-doped C60 (KxC60) monolayers\nover a wide regime of the phase diagram. As K content increases from x = 3 to\n5, KxC60 monolayers undergo metal-insulator-metal reentrant phase transitions\nand exhibit a variety of novel orientational orderings. The most striking new\nstructure has a pinwheel-like 7-molecule unit cell in insulating K4+dC60. We\npropose that the driving mechanism for the orientational ordering in KxC60 is\nthe lowering of electron kinetic energy through maximization of the overlap of\nneighboring molecular orbitals over the entire doping range x = 3 to 5. In the\ninsulating and metallic phases this gives rise to orbital versions of the\nsuperexchange and double-exchange interactions respectively."
    },
    {
        "anchor": "Hidden structural order controls Li-ion transport in cation-disordered\n  oxides for rechargeable lithium batteries: Crystal structures play a vital role in determining materials properties. In\nLi-ion cathodes, the crystal structure defines the dimensionality and\nconnectivity of interstitial sites, thus determining Li-ion diffusion kinetics.\nWhile a perfect crystal has infinite structural coherence, a class of recently\ndiscovered high-capacity cathodes, Li-excess cation-disordered rocksalts, falls\non the other end of the spectrum: Their cation sublattices are assumed to be\nrandomly populated by Li and transition metal ions with zero configurational\ncoherence based on conventional X-ray diffraction, such that the Li transport\nis purely determined by statistical effects. In contrast to this prevailing\nview, we reveal that cation short-range order, hidden in diffraction, is\nubiquitous in these long-range disordered materials and controls the local and\nmacroscopic environments for Li-ion transport. Our work not only discovers a\ncrucial property that has previously been overlooked, but also provides new\nguidelines for designing and engineering disordered rocksalts cathode\nmaterials.",
        "positive": "Epitaxy, exfoliation, and strain-induced magnetism in rippled Heusler\n  membranes: Single-crystalline membranes of functional materials enable the tuning of\nproperties via extreme strain states; however, conventional routes for\nproducing membranes require the use of sacrificial layers and chemical\netchants, which can both damage the membrane and limit the ability to make them\nultrathin. Here we demonstrate the epitaxial growth of the cubic Heusler\ncompound GdPtSb on graphene-terminated Al$_2$O$_3$ substrates. Despite the\npresence of the graphene interlayer, the Heusler films have epitaxial registry\nto the underlying sapphire, as revealed by x-ray diffraction, reflection high\nenergy electron diffraction, and transmission electron microscopy. The weak Van\nder Waals interactions of graphene enable mechanical exfoliation to yield\nfree-standing GdPtSb membranes, which form ripples when transferred to a\nflexible polymer handle. Whereas unstrained GdPtSb is antiferromagnetic,\nmeasurements on rippled membranes show a spontaneous magnetic moment at room\ntemperature, with a saturation magnetization of 5.2 bohr magneton per Gd.\nFirst-principles calculations show that the coupling to homogeneous strain is\ntoo small to induce ferromagnetism, suggesting a dominant role for strain\ngradients. Our membranes provide a novel platform for tuning the magnetic\nproperties of intermetallic compounds via strain (piezomagnetixm and\nmagnetostriction) and strain gradients (flexomagnetism)."
    },
    {
        "anchor": "Broadband Terahertz Modulation in Electrostatically-doped Artificial\n  Trilayer Graphene: We report a terahertz optical modulator consisting of randomly stacked\ntrilayer graphene (TLG) deposited on an oxidized silicon substrate by means of\nTHz- Time Domain Spectroscopy (THz-TDS). Here, the gate tuning of the Fermi\nlevel of the TLG provides the fundamental basis for the modulation of THz\ntransmission. We measured a 15% change in the THz transmission of this device\nover a broad frequency range (0.6-1.6THz). We also observed a strong absorption\n>80% in the time-domain signals and a frequency independence of the\nconductivity. Furthermore, unlike previous studies, we find that the underlying\nsilicon substrate, which serves as a gate electrode for the graphene, also\nexhibits substantial modulation of the transmitted THz radiation under applied\nvoltage biases.",
        "positive": "Observation of a Large Photo-response in a Single Nanowire (Diameter ~30\n  nm) of Charge Transfer Complex Cu:TCNQ: We report for the first time large photoresponse in a single NW of the charge\ntransfer complex Cu:TCNQ. We fabricate a metal-semiconductor-metal device with\na single NW and focus ion beam deposited Pt. We observe large photocurrent even\nat zero bias. The spectral dependence of the photoresponse follows the main\nabsorption at ~ 405 nm which has the primarily responsible for photogenerated\ncarriers. We have quantitatively analyzed the bias dependent photocurrent by a\nmodel of two back to back Schottky diodes connected by a series resistance. The\nobservation shows that the large photoresponse of the device primarily occurs\ndue to the reduction of the barrier at the contact regions due to illumination\nalong with the photoconductive contribution. There is also a bias driven\nreduction of the nanowire resistance that is a unique feature for the material."
    },
    {
        "anchor": "Ultrathin ferrimagnetic GdFeCo films with very low damping: Ferromagnetic materials dominate as the magnetically active element in\nspintronic devices, but come with drawbacks such as large stray fields, and low\noperational frequencies. Compensated ferrimagnets provide an alternative as\nthey combine the ultrafast magnetization dynamics of antiferromagnets with a\nferromagnet-like spin-orbit-torque (SOT) behavior. However to use ferrimagnets\nin spintronic devices their advantageous properties must be retained also in\nultrathin films (t < 10 nm). In this study, ferrimagnetic Gdx(Fe87.5Co12.5)1-x\nthin films in the thickness range t = 2-20 nm were grown on high resistance\nSi(100) substrates and studied using broadband ferromagnetic resonance\nmeasurements at room temperature. By tuning their stoichiometry, a nearly\ncompensated behavior is observed in 2 nm Gdx(Fe87.5Co12.5)1-x ultrathin films\nfor the first time, with an effective magnetization of Meff = 0.02 T and a low\neffective Gilbert damping constant of {\\alpha} = 0.0078, comparable to the\nlowest values reported so far in 30 nm films. These results show great promise\nfor the development of ultrafast and energy efficient ferrimagnetic spintronic\ndevices.",
        "positive": "Degradation mechanism of CH3NH3PbI3 perovskite materials upon exposure\n  to humid air: Low stability of organic-inorganic perovskite (CH3NH3PbI3) solar cells in\nhumid air environments is a serious drawback which could limit practical\napplication of this material severely. In this study, from real-time\nspectroscopic ellipsometry characterization, the degradation mechanism of\nultra-smooth CH3NH3PbI3 layers prepared by a laser evaporation technique is\nstudied. We present evidence that the CH3NH3PbI3 degradation in humid air\nproceeds by two competing reactions of (i) the PbI2 formation by the desorption\nof CH3NH3I species and (ii) the generation of a CH3NH3PbI3 hydrate phase by H2O\nincorporation. In particular, rapid phase change occurs in the near-surface\nregion and the CH3NH3PbI3 layer thickness reduces rapidly in the initial 1-h\nair exposure even at a low relative humidity of 40%. After the prolonged air\nexposure, the CH3NH3PbI3 layer is converted completely to hexagonal platelet\nPbI2/hydrate crystals that have a distinct atomic-scale multilayer structure\nwith a period of 0.65 nm. We find that conventional x-ray diffraction and\noptical characterization in the visible region, used commonly in earlier works,\nare quite insensitive to the surface phase change. Based on results obtained in\nthis work, we discuss the degradation mechanism of CH3NH3PbI3 in humid air."
    },
    {
        "anchor": "Nanoscale Electromechanics of Paraelectric Materials with Mobile\n  Charges: Size effects and Nonlinearity of Electromechanical Response of\n  SrTiO3 Films: Nanoscale enables a broad range of electromechanical coupling mechanisms that\nare forbidden or negligible in the materials. We conduct a theoretical study of\nthe electromechanical response of thin paraelectric films with mobile vacancies\n(or ions) paradigmatic for capacitor-type measurements in X-ray scattering,\npiezoresponse force microscopy (PFM), and electrochemical strain microscopy\n(ESM). Using quantum paraelectric SrTiO3 film as a model material with well\nknown electromechanical, electronic and electrochemical properties, we evaluate\nthe contributions of electrostriction, Maxwell stress, flexoelectric effect,\ndeformation potential and compositional Vegard strains caused by mobile\nvacancies (or ions) and electrons to the electromechanical response. The local\nelectromechanical response manifests strong size effects, the scale of which is\ndetermined by the ratio of the SrTiO3 film thickness and PFM/ESM tip size to\nthe carriers screening radius. Due to the strong dielectric nonlinearity effect\ninherent in quantum paraelectrics, the dependence of the SrTiO3 film\nelectromechanical response on applied voltage demonstrates a pronounced\ncrossover from the linear to the quadratic law and then to the sub-linear law\nwith a factor of 2/3 under the voltage increase. The temperature dependence of\nthe electromechanical response as determined by the interplay between the\ndielectric susceptibility and the screening radius is non-monotonic and has a\npronounced maxima, the position and width of which can be tuned by film\nthickness. This study provides a comparative framework for analysis of\nelectromechanical coupling in the non-piezoelectric nanosystems.",
        "positive": "Effect of Fe-substitution on the structure and magnetism of single\n  crystals Mn2-xFexBO4: Single crystalline Mn2-xFexBO4 with x = 0.3, 0.5, 0.7 grown by the flux\nmethod have been studied by means of X-ray diffraction and X-ray absorption\nspectroscopy at both Mn and Fe K edges. The compounds were found to crystallize\nin an orthorhombic warwickite structure (sp. gr. Pnam). The magnetization data\nhave revealed a spin-glass transition at TSG= 11, 14 and 18 K for x= 0.3, 0.5\nand 0.7, respectively."
    },
    {
        "anchor": "Stacking and band structure of van der Waals bonded graphane multilayers: We use density functional theory and the van der Waals density functional\n(vdW-DF) method to determine the binding separation in bilayer and bulk\ngraphane and study the changes in electronic band structure that arise with the\nmultilayer formation. The calculated binding separation (distance between\ncenter-of-mass planes) and binding energy are 4.5-5.0 {\\AA} (4.5-4.8 {\\AA}) and\n75-102 meV/cell (93-127 meV/cell) in the bilayer (bulk), depending on the\nchoice of vdW-DF version. We obtain the corresponding band diagrams using\ncalculations in the ordinary generalized gradient approximation for the\ngeometries specified by our vdW-DF results, so probing the indirect effect of\nvdW forces on electron behavior. We find significant band-gap modifications by\nup to -1.2 eV (+4.0 eV) in various regions of the Brillouin zone, produced by\nthe bilayer (bulk) formation.",
        "positive": "Electron Energy Loss Function of Silicene and Germanene Multilayers on\n  Silver: We calculate electron energy loss spectra (EELS) for composite plasmonic\nstructures based on silicene and germanene. A continued-fraction expression for\nthe effective dielectric function is used to perform multiscale calculations of\nEELS for both silicene and germanene-based structures on silver substrates. A\ndistinctive change in plasmonic response occurs for structures with a germanene\nor silicene surface coating of more than three layers. These differences may be\nexploited using spectroscopic characterization in order to determine if a\nfew-layer coating has been successfully fabricated."
    },
    {
        "anchor": "Observation of inverse spin Hall effect in bismuth selenide: Bismuth Selenide (Bi2Se3) is a topological insulator exhibiting helical spin\npolarization and strong spin-orbit coupling. The spin-orbit coupling links the\ncharge current to spin current via the spin Hall effect (SHE). We demonstrate a\nBi2Se3 spin detector by injecting the pure spin current from a magnetic\npermalloy layer to a Bi2Se3 thin film and detect the inverse SHE in Bi2Se3. The\nspin Hall angle of Bi2Se3 is found to be 0.0093 and the spin diffusion length\nin Bi2Se3 to be 6.2 nm at room temperature. Our results suggest that\ntopological insulators with strong spin-orbit coupling can be used in\nfunctional spintronic devices.",
        "positive": "Atomistic modeling of Li- and post-Li ion batteries: Alkali metal ion batteries, and in particular Li-ion batteries, have become a\nkey technology for current and future energy storage, already nowadays powering\nmany devices of our daily lives. Due to the inherent complexity of batteries\nand their components, the use of computational approaches on all length and\ntime scales has been largely evolving within recent years. Gaining insight in\ncomplex processes or predicting new materials for specific applications are two\nof the main perspectives computational studies can offer, making them a\nindispensable tool of modern material science and hence battery research. After\na short introduction to battery technology, this review will first focus on the\ntheoretical concepts that underlie the functioning of Li- and post-Li-ion\nbatteries. This will be followed by a discussion of the most prominent\ncomputational methods and their applications, currently available for the\ninvestigation of battery materials on an atomistic scale."
    },
    {
        "anchor": "Carbon Nanotubes in Biology and Medicine: in vitro and in vivo\n  Detection, Imaging and Drug Delivery: Carbon nanotubes exhibit many unique intrinsic physical and chemical\nproperties and have been intensively explored for biological and biomedical\napplications. In this review, we summarize the main results of our and other\ngroups in this field and clarify that surface functionalization is critical to\nthe behaviors of carbon nanotubes in biological systems. Ultra-sensitive\ndetection of biological species with carbon nanotubes can be realized after\nsurface passivation to inhibit the non-specific binding of bio-molecules on the\nhydrophobic nanotube surface. Electrical nanosensors based on nanotubes provide\na label-free approach to biological detections. Surface enhanced Raman\nspectroscopy of CNT opens up a method of protein microarray with down to 1 fM\ndetection sensitivity. In vitro and in vivo toxicity studies reveal that well\nwater soluble and serum stable nanotubes are biocompatible, non-toxic and\npotentially useful for biomedical applications. In vivo biodistributions vary\nwith the functionalization and possibly also sizes of nanotubes, with a\ntendency of accumulation in the reticuloendothelial systems, including the\nliver and spleen, after intravenous administration. If well functionalized,\nnanotubes may be excreted mainly through the biliary pathway in feces. Carbon\nnanotube-based drug delivery has shown promises in various in vitro and in vivo\nexperiments including delivery pf small interfering RNA, paclitaxel and\ndoxorubicin. Moreover, SWNTs with various interesting intrinsic optical\nproperties have been used as novel photoluminance, Raman and photoacoustic\ncontrast agents for imaging of cells and animals. Further multidisciplinary\nexplorations in this field are promising and may bring new opportunities to the\nrealm of biomedicine.",
        "positive": "Towards the insulator-to-metal transition at the surface of ion-gated\n  nanocrystalline diamond films: Hole doping can control the conductivity of diamond either through boron\nsubstitution, or carrier accumulation in a field-effect transistor. In this\nwork, we combine the two methods to investigate the insulator-to-metal\ntransition at the surface of nanocrystalline diamond films. The finite boron\ndoping strongly increases the maximum hole density which can be induced\nelectrostatically with respect to intrinsic diamond. The ionic gate pushes the\nconductivity of the film surface away from the variable-range hopping regime\nand into the quantum critical regime. However, the combination of the strong\nintrinsic surface disorder due to a non-negligible surface roughness, and the\nintroduction of extra scattering centers by the ionic gate, prevents the\nsurface accumulation layer to reach the metallic regime."
    },
    {
        "anchor": "Metastable Interlayer Frenkel Pair Defects by Dipole-like Strain Fields\n  for Dimensional Distortion in Black Phosphorus: The low formation energy of atomic vacancies in black phosphorus allows it to\nserve as an ideal prototypical system for exploring the dynamics of interlayer\ninterstitial-vacancy (I-V) pairs (i.e. Frenkel defects) which account for\nWigner energy release. Based on a few-layer model of black phosphorus, we\nconduct discrete geometry analysis and investigate the structural dynamics of\nintimate interlayer Frenkel pairs from first-principles calculations. We reveal\na highly metastable I-V pair state driven by anisotropic dipole-like strain\nfields which can build strong connections between neighbouring layers. In the\n2D limit (monolayer), the intimate I-V pair exhibits a relatively low formation\nenergy of 1.54 eV and is energetically favoured over its isolated constituents\nby up to 1.68 eV. The barrier for annihilation of the Frenkel pair is 1.46 eV\nin the bilayer, which is remarkably higher than that of similar defects in\ngraphite. The findings reported in this work suggest that there exist rich\nbridging pathways in black phosphorus, leading to stable dimensional reduction\nand structural condensation on exposure to moderate electron excitation or\nthermal annealing. This study paves the way for creating novel\ndimensional-hybrid polymorphs of phosphorus via the introduction of such\nmetastable interlayer I-V pair defects.",
        "positive": "Universal properties of magnetization dynamics in polycrystalline\n  ferromagnetic films: We investigate the scaling behavior in the statistical properties of\nBarkhausen noise in ferromagnetic films. We apply the statistical treatment\nusually employed for bulk materials in experimental Barkhausen noise time\nseries measured with the traditional inductive technique in polycrystalline\nferromagnetic films having different thickness from 100 up to 1000 nm, and\ninvestigate the scaling exponents. Based on this procedure, we can group the\nsamples in a single universality class, characterized by exponents \\tau \\sim\n1.5, \\alpha \\sim 2.0, and 1/\\sigma \\nu z \\sim \\vartheta \\sim 2.0. We interpret\nthese results in terms of theoretical models and provide experimental evidence\nthat a well-known mean-field model for the dynamics of a ferromagnetic domain\nwall in three-dimensional ferromagnets can be extended for films. We identify\nthat the films present an universal three-dimensional magnetization dynamics,\ngoverned by long-range dipolar interactions, even at the smallest thicknesses,\nindicating that the two-dimensional magnetic behavior commonly verified for\nfilms cannot be generalized for all thickness ranges."
    },
    {
        "anchor": "Density functional theory calculations for investigation of atomic\n  structures of 4H-SiC/SiO$_2$ interface after NO annealing: We propose the atomic structures of the 4H-SiC/SiO$_2$ interface for the $a$,\n$m$, C, and Si faces after NO annealing. Our proposed structures preferentially\nform at the topmost layers of the SiC side of the interface, which agrees with\nthe experimental finding of secondary-ion mass spectrometry, that is, the N\natoms accumulate at the interface. In addition, the areal N-atom density is on\nthe order of 10$^{14}$ atom/cm$^2$ for each plane, which is also consistent\nwith the experimental result. Moreover, the electronic structure of the\ninterface after NO annealing, in which the CO bonds are removed and the nitride\nlayer only at the interface is inserted, is free from gap states, although some\ninterface models before NO annealing include the gap states arising from the CO\nbonds near the valence band edge of the bandgap. Our results imply that NO\nannealing can contribute to the reduction in the density of interface defects\nby forming the nitride layer.",
        "positive": "Magnetoresistance and Shubnikov-de Hass oscillation in YSb: YSb crystals are grown and the transport properties under magnetic field are\nmeasured. The resistivity exhibits metallic behavior under zero magnetic field\nand the low temperature resistivity shows a clear upturn once a moderate\nmagnetic field is applied. The upturn is greatly enhanced by increasing\nmagnetic field, finally resulting in a metal-to-insulator-like transition. With\ntemperature further decreased, a resistivity plateau emerges after the\ninsulator-like regime. At low temperature (2.5 K) and high field (14 T), the\ntransverse magnetoresistance (MR) is quite large (3.47 $\\times 10^4\\%$ ). In\naddition, Shubnikov-de Haas (SdH) oscillation has also been observed in YSb.\nPeriodic behavior of the oscillation amplitude reveals the related information\nabout Fermi surface and two major oscillation frequencies can be obtained from\nthe FFT spectra of the oscillations. The trivial Berry phase extracted from SdH\noscillation, band structure revealed by angle-resolved photoemission\nspectroscopy (ARPES) and first-principles calculations demonstrate that YSb is\na topologically trivial material."
    },
    {
        "anchor": "Optimized Effective Potential Model for the Double Perovskites\n  Sr2-xYxVMoO6 and Sr2-xYxVTcO6: In attempt to explore half-metallic properties of the double perovskites\nSr2-xYxVMoO6 and Sr2-xYxVTcO6, we construct an effective low-energy model,\nwhich describes the behavior of the t2g-states of these compounds. All\nparameters of such model are derived rigorously on the basis of\nfirst-principles electronic structure calculations. In order to solve this\nmodel we employ the optimized effective potential method and treat the\ncorrelation interactions in the random phase approximation. Although\ncorrelation interactions considerably reduce the intraatomic exchange splitting\nin comparison with the Hartree-Fock method, this splitting still substantially\nexceeds the typical values obtained in the local-spin-density approximation\n(LSDA), which alters many predictions based on the LSDA. Our main results are\nsummarized as follows: (i) all ferromagnetic states are expected to be\nhalf-metallic. However, their energies are generally higher than those of the\nferrimagnetic ordering between V- and Mo/Tc-sites (except Sr2VMoO6); (ii) all\nferrimagnetic states are metallic (except fully insulating Y2VTcO6) and no\nhalf-metallic antiferromagnetism has been found; (iii) moreover, many of the\nferrimagnetic structures appear to be unstable with respect to the spin-spiral\nalignment. Thus, the true magnetic ground state of the most of these systems is\nexpected to be more complex. In addition, we discuss several methodological\nissues related to the nonuniqueness of the effective potential for the magnetic\nhalf-metallic and insulating states.",
        "positive": "Magnetic interactions and excitations in SrMnSb$_2$: The magnetic interactions in the antiferromagnetic (AFM) Dirac semimetal\ncandidate SrMnSb$_2$ are investigated using \\textit{ab initio} linear response\ntheory and inelastic neutron scattering (INS). Our calculations reveal that the\nfirst two nearest in-plane couplings ($J_1$ and $J_2$) are both AFM in nature,\nindicating a significant degree of spin frustration, which aligns with\nexperimental observations. The orbital resolution of exchange interactions\nshows that $J_1$ and $J_2$ are dominated by direct and superexchange,\nrespectively. In a broader context, a rigid-band model suggests that electron\ndoping fills the minority spin channel and results in a decrease in the AFM\ncoupling strength for both $J_1$ and $J_2$. To better compare with INS\nexperiments, we calculate the spin wave spectra within a linear spin wave\ntheory framework, utilizing the computed exchange parameters. The calculated\nspin wave spectra exhibit overall good agreement with measurements from INS\nexperiments, although with a larger magnon bandwidth. Introducing additional\nelectron correlation within the Mn-$3d$ orbitals can promote electron\nlocalization and reduce the magnetic coupling, further improving the agreement\nwith experiments."
    },
    {
        "anchor": "Rapid screening of high-throughput ground state predictions: High-through computational thermodynamic approaches are becoming an\nincreasingly popular tool to uncover novel compounds. However, traditional\nmethods tend to be limited to stability predictions of stoichiometric phases at\nabsolute zero. Such methods thus carry the risk of identifying an excess of\npossible phases that do not survive to temperatures of practical relevance. We\ndemonstrate how the Calphad formalism, informed by simple first-principles\ninput can be simply used to overcome this problem at a low computational cost\nand deliver quantitatively useful phase diagram predictions at all\ntemperatures. We illustrate the method by re-assessing prior compound formation\npredictions and reconcile these findings with long-standing experimental\nevidence to the contrary.",
        "positive": "Strain-Hardening Stages and Structure Evolution in Pure Niobium and\n  Vanadium upon High Pressure Torsion: High pressure torsion (HPT) is one of the ways to form nanostructured\nmaterials with high strength properties. However, HPT hardening mechanisms vary\nfrom material to material and are poorly understood for some BCC metals,\nparticularly niobium and vanadium. This work aims to identify strain hardening\nstages for Nb and V metals during HPT. Two approaches have been used to\nidentify the deformation stages during high pressure torsion. The approaches\nare based on the application of a \"piecewise\" model, taking into account the\ndifferent deformation mechanisms that determine the type of the forming\nstructure, and on the analysis of the hardness vs. true strain dependence\naccording to the $H$$-$${e}^{0.5}$ law. We compared the identified stages with\nthe results of the electron microscopic study of the structure. Both models\ndescribe well the structural changes observed microscopically in HPT-deformed\nniobium. However, we have shown that only the piecewise model gives an adequate\ndescription of the stages of structure development in vanadium. We have\nprovided an explanation for the observed difference in the behavior of niobium\nand vanadium upon HPT."
    },
    {
        "anchor": "Avalanches in 2D Dislocation Systems: Plastic Yielding is not Depinning: We study the properties of strain bursts (dislocation avalanches) occurring\nin two-dimensional discrete dislocation dynamics models under quasistatic\nstress-controlled loading. Contrary to previous suggestions, the avalanche\nstatistics differs fundamentally from predictions obtained for the depinning of\nelastic manifolds in quenched random media. Instead, we find an exponent \\tau\n=1 of the power-law distribution of slip or released energy, with a cut-off\nthat increases exponentially with the applied stress and diverges with system\nsize at all stresses. These observations demonstrate that the avalanche\ndynamics of 2D dislocation systems is scale-free at every applied stress and,\ntherefore, can not be envisaged in terms of critical behavior associated with a\ndepinning transition.",
        "positive": "Thermal expansion and compressibility of monogermanides of 3d-metals: Synchrotron diffraction as a function of temperature and pressure, specific\nheat, magnetic susceptibility and small-angle neutron scattering experiments\nhave revealed an anomalous response of MnGe. Similar but less pronounced\nbehavior has also been observed in Mn$_{1-x}$Co$_x$Ge and Mn$_{1-x}$Fe$_x$Ge\nsolid solutions. Spin density fluctuations and Mn spin state instability are\ndiscussed as possible candidates for the observed effects."
    },
    {
        "anchor": "Surface-state-dominated transport in crystals of the topological\n  crystalline insulator In-doped Pb$_{1-x}$Sn$_x$Te: Three-dimensional topological insulators and topological crystalline\ninsulators represent new quantum states of matter, which are predicted to have\ninsulating bulk states and spin-momentum-locked gapless surface states.\nExperimentally, it has proven difficult to achieve the high bulk resistivity\nthat would allow surface states to dominate the transport properties over a\nsubstantial temperature range. Here we report a series of indium-doped\nPb$_{1-x}$Sn$_x$Te compounds that manifest huge bulk resistivities together\nwith strong evidence of topological surface states, based on\nthickness-dependent transport studies and magnetoresistance measurements. For\nthese bulk-insulating materials, the surface states determine the resistivity\nfor temperatures approaching 30 K.",
        "positive": "Porous Semiconductors: Growth and Applications: Big pores, small pores, ordered pores, random pores, they all have a function\nand as is often found, show behaviour in new materials that is not always\npredicted or obvious at the outset. I started my research journey trying to put\nextremely thin films onto near-perfect III-V crystals to control\n(opto)electronic properties and when the first TEM on our campus showed\nremarkable pore growth and structure in InP almost 21 years ago, the\nelectrochemical modification of the InP made more sense. In this paper, I will\nsummarise a few aspects of research into porous materials and semiconductors,\nfrom porous InP that led to studies of other porous semiconductors such as\nsilicon, GaN, ZnO and Indium Tin oxide (ITO), to periodically ordered photonic\ncrystal porous structures and some optical, thermal and electrochemical\nproperties, photocatalysis, studies in batteries and related that were enabled\nor modified by the porous structure."
    },
    {
        "anchor": "Asymmetric magnetization reversal in the exchange bias system Fe/FeF_2\n  studied by MOKE: The asymmetry of the magnetization reversal process in exchange biased\nFe/FeF$_2$ has been studied by magneto-optical Kerr effect. Qualitatively\ndifferent transverse magnetization loops are observed for different directions\nof the cooling and the measuring field. These loops can be simulated by a\nsimple calculation of the total energy density which includes the relevant\nmagnetic anisotropies and coherent magnetization rotation only. Asymmetric\nmagnetization reversal is shown to originate from the unidirectional anisotropy\nand may be observed if the external measuring field is not collinear with\neither the exchange bias or the easy axis of the antiferromagnetic epitaxial\nFeF$_2$(110) layer.",
        "positive": "Electronic structure and magnetic properties of graphene/Co composites: The results of measurements of XPS spectra and magnetic properties of\ngraphene/Co composites prepared by adding of CoCl$_2$x6H$_2$O diluted in ethyl\nalcohol to highly-splitted graphite are presented. XPS Co 2p measurements show\ntwo sets of 2p$_{3/2,1/2}$-lines belonging to oxidized and metallic Co-atoms.\nThis means that metal in composite is partly oxidized. This conclusion is\nconfirmed by magnetic measurements which show the presence of the main (from\nthe metal) and shifted (from the oxide) hysteresis loops. The presence of oxide\nlayer on the metal surface prevents the metal from the full oxidation and (as\nshown by magnetic measurements) provides the preservation of ferromagnetic\nproperties after long exposure in ambient air which enables the use of\ngraphene/metal composites in spintronics devices."
    },
    {
        "anchor": "The Angell Plot from the Potential Energy Landscape Perspective: Within the scenario of the potential energy landscape (PEL), a thermodynamic\nmodel has been developed to uncover the physics behind the Angell plot. In our\nmodel, by separating the barrier distribution in PELs into a Gaussian-like and\na power-law form, we obtain a general relationship between the relaxation time\nand the temperature. The wide range of the experimental data in the Angell\nplot, as well as the molecular-dynamics data, can be excellently fitted by two\ncharacteristic parameters, the effective barrier ({\\omega}) and the effective\nwidth ({\\sigma}) of a Gaussian-like distribution. More importantly, the fitted\n{\\omega} and {\\sigma}^2 for all glasses are found to have a simple linear\nrelationship within a very narrow band, and fragile and strong glasses are well\nseparated in the {\\omega}-{\\sigma}^2 plot, which indicates that glassy states\nonly appear in a specific region of the PEL.",
        "positive": "Pressure dependent electronic properties of MgO polymorphs: A\n  first-principles study of Compton profiles and autocorrelation functions: The first-principles periodic linear combination of atomic orbitals method\nwithin the framework of density functional theory implemented in the CRYSTAL06\ncode has been applied to explore effect of pressure on the Compton profiles and\nautocorrelation functions of MgO. Calculations are performed for the B1, B2,\nB3, B4, B8_1 and h-MgO polymorphs of MgO to compute lattice constants and bulk\nmoduli. The isothermal enthalpy calculations predict that B4 to B8_1, h-MgO to\nB8_1, B3 to B2, B4 to B2 and h-MgO to B2 transitions take place at 2, 9, 37, 42\nand 64 GPa respectively. The high pressure transitions B8_1 to B2 and B1 to B2\nare found to occur at 340 and 410 GPa respectively. The pressure dependent\nchanges are observed largely in the valence electrons Compton profiles whereas\ncore profiles are almost independent of the pressure in all MgO polymorphs.\nIncrease in pressure results in broadening of the valence Compton profiles. The\nprincipal maxima in the second derivative of Compton profiles shifts towards\nhigh momentum side in all structures. Reorganization of momentum density in the\nB1 to B2 structural phase transition is seen in the first and second\nderivatives before and after the transition pressure. Features of the\nautocorrelation functions shift towards lower r side with increment in\npressure."
    },
    {
        "anchor": "Structural, electronic, and magnetic properties of CrTe2: Two-dimensional chromium ditelluride (CrTe2) is a promising ferromagnetic\nlayered material that exhibits long-range ferromagnetic ordering in the\nmonolayer limit. The formation energies of the different possible structural\nphases (1T, 1H, 2H) calculated from density functional theory (DFT) show that\nthe 1T phase is the ground state, and the energetic transition barriers between\nthe phases, calculated by the nudged elastic band method, are large, on the\norder of 0.5 eV. The self-consistent Hubbard $U$ correction parameters are\ncalculated for all the phases of CrTe$_2$. The calculated magnetic moment of\n1T-CrTe$_2$ with $\\geq 2$ layers lies in the plane, whereas the magnetic moment\nof a monolayer is out-of-plane. Band filling and tensile bi-axial strain cause\nthe magnetic moment of a monolayer to switch from out-of-plane to in-plane, and\ncompressive bi-axial strain in a bilayer causes the magnetic moment to switch\nfrom in-plane to out-of-plane. The magnetic anisotropy is shown to originate\nfrom the large spin orbit coupling (SOC) of the Te atoms and the anisotropy of\nthe exchange coupling constants $J_{xy}$ and $J_z$ in an XXZ type Hamiltonian.\nRenormalized spin wave theory using experimental values for the magnetic\nanisotropy energy and Curie temperatures provides a range of values for the\nnearest neighbor exchange coupling.",
        "positive": "Density functional theory calculation of edge stresses in monolayer\n  MoS$_2$: We utilize density functional theory to calculate the edge energy and edge\nstress for monolayer MoS$_{2}$ nanoribbons. In contrast to previous reports for\ngraphene, for both armchair and zigzag chiralities, the edge stresses for\nMoS$_{2}$ nanoribbons are found to be tensile, indicating that their lowest\nenergy configuration is one of compression in which Mo-S bond lengths are\nshorter than those in a bulk, periodic MoS$_{2}$ monolayer. The edge energy and\nedge stress is found to converge for both chiralities for nanoribbon widths\nlarger than about 1 nm."
    },
    {
        "anchor": "Evidence of charge density wave with anisotropic gap in monolayer\n  VTe$_2$ film: We report experimental evidence of charge density wave (CDW) transition in\nmonolayer 1T-VTe$_2$ film. 4$\\times$4 reconstruction peaks are observed by low\nenergy electron diffraction below the transition temperature $T_{CDW}$ = 186 K.\nAngle-resolved photoemission spectroscopy measurements reveal arc-like pockets\nwith anisotropic CDW gaps up to 50 meV. The anisotropic CDW gap is attributed\nto the imperfect nesting of the CDW wave vector, and first-principles\ncalculations reveal phonon softening at the same vector, suggesting the\nimportant roles of Fermi surface nesting and electron-phonon interaction in the\nCDW mechanism.",
        "positive": "Critical analysis of the slope method for estimation of ice-water\n  interfacial energy from ice nucleation experimental data (with reviews): An established procedure for the estimation of ice-water interfacial energy\nbased on evaluation of the slope of the experimental ice nucleation rate data\nversus scaled temperature is critically analyzed in this work. An inconsistent\nestimate of the ice-water interfacial energy is found in the work of Murray et\nal. [Phys. Chem. Chem. Phys., 2010, 12, 10380-10387]. The source of the\ninconsistency is identified in an inappropriate regression method used for\nexperimental ice nucleation data fitting, a correct estimate of the ice-water\ninterfacial energy is presented, and limits of the slope method are discussed."
    },
    {
        "anchor": "Enhanced Thermoelectric ZT in the Tails of the Fermi Distribution via\n  Electron Filtering by Nanoinclusions -- Model Electron Transport in\n  Nanocomposites: Silicon carbide nanoparticles with diameters around 8 nm and with narrow size\ndistribution have been finely mixed with doped silicon nanopowders and sintered\ninto bulk samples to investigate the influence of nanoinclusions on electrical\nand thermal transport properties. We have compared the thermoelectric\nproperties of samples ranging from 0-5% volume fraction of silicon carbide. The\nsilicon carbide nanoinclusions lead to a significant improvement in the\nthermoelectric figure of merit, ZT, largely due to an enhancement of the\nSeebeck coefficient. A semiclassical Boltzmann transport equation is used to\nmodel the electrical transport properties of the Seebeck coefficient and\nelectrical conductivity. The theoretical analysis confirms that the\nenhancements in the thermoelectric properties are consistent with the energy\nselective scattering of electrons induced by the offset between the silicon\nFermi level and the carbide conduction band edge. This study proves that\ncareful engineering of the energy-dependent electron scattering rate can\nprovide a route towards relaxing long-standing constraints in the design of\nthermoelectric materials.",
        "positive": "Theoretical prediction of a highly responsive material: Spin\n  fluctuations and superconductivity in FeNiB2 system: By analyzing Fe-Ni-B compositional diagram we predict an energetically and\ndynamically stable FeNiB2 compound. This system belongs to the class of highly\nresponsive state of material, as it is very sensitive to the external\nperturbations. This state is also characterized by a high level of spin\nfluctuations which strongly influence possible magnetic long- and short-range\norders. Furthermore, we demonstrate that these antiferromagnetically dominating\nfluctuations could lead to the appearance of spin mediated superconductivity.\nThe obtained results suggest a promising avenue for the search of strong spin\nfluctuation systems and related superconductors."
    },
    {
        "anchor": "Real-space formulation of orbital-free density functional theory using\n  finite-element discretization: The case for Al, Mg, and Al-Mg intermetallics: We propose a local real-space formulation for orbital-free DFT with density\ndependent kinetic energy functionals and a unified variational framework for\ncomputing the configurational forces associated with geometry optimization of\nboth internal atomic positions as well as the cell geometry. The proposed\nreal-space formulation, which involves a reformulation of the extended\ninteractions in electrostatic and kinetic energy functionals as local\nvariational problems in auxiliary potential fields, also readily extends to\nall-electron orbital-free DFT calculations that are employed in warm dense\nmatter calculations. We use the local real-space formulation in conjunction\nwith higher-order finite-element discretization to demonstrate the accuracy of\norbital-free DFT and the proposed formalism for the Al-Mg materials system,\nwhere we obtain good agreement with Kohn-Sham DFT calculations on a wide range\nof properties and benchmark calculations. Finally, we investigate the cell-size\neffects in the electronic structure of point defects, in particular a\nmono-vacancy in Al. We unambiguously demonstrate that the cell-size effects\nobserved from vacancy formation energies computed using periodic boundary\nconditions underestimate the extent of the electronic structure perturbations\ncreated by the defect. On the contrary, the bulk Dirichlet boundary conditions,\naccessible only through the proposed real-space formulation, which correspond\nto an isolated defect embedded in the bulk, show cell-size effects in the\ndefect formation energy that are commensurate with the perturbations in the\nelectronic structure. Our studies suggest that even for a simple defect like a\nvacancy in Al, we require cell-sizes of $\\sim 10^3$ atoms for convergence in\nthe electronic structure.",
        "positive": "Ferrimagnetism and spin canting of ZnFe2O4 nanoparticles embedded in ZnO\n  matrix: The structural and magnetic properties of ZnFe2O4 nanoparticles embedded in a\nnon-magnetic ZnO matrix are presented. X-ray diffractograms and Transmission\nElectron Microscopy (TEM) images showed that the resulting samples are composed\nof crystalline ferrite nanoparticles with average crystallite size <D> =\n23.4(0.9) nm, uniformly dispersed within the ZnO matrix. Magnetization data\nindicated a superparamagnetic-like behavior from room temperature down to T_{M}\n~ 20 K, where a transition to a frozen state is observed. The M(H) curves\ndisplayed nearly zero coercive field down to TM, where a sharp increase in the\nH_C value is observed. The measured saturation magnetization M_S values at 200\nand 2 K were M_S = 0.028(3) and 0.134(7) muB/f.u. ZnFe2O4 respectively, showing\nthe existence of small amounts of non compensated atomic moments. M\\\"ossbauer\nmeasurements at low temperatures confirmed the transition to a magnetically\nordered state for T < 25 K, where two magnetically split sextets develop.\nWhereas these two sextets show strong overlap due to the similar hyperfine\nfields, in-field M\\\"ossbauer spectra clearly showed two different Fe3+ sites,\ndemonstrating that the sample is ferrimagnetically ordered. The two spinel\nsites are found to behave differently under an external field of 12 T: whereas\nthe moments located at A sites show a perfect alignment with the external\nfield, spins at B sites are canted by an angle alpha_B = 49(2){\\deg}. We\ndiscuss the significance of this particle structure for the observed magnetic\nbehavior."
    },
    {
        "anchor": "In-plane anisotropic optical and mechanical properties of\n  two-dimensional MoO$_3$: Molybdenum trioxide (MoO$_3$) in-plane anisotropy has increasingly attracted\nthe attention of the scientific community in the last few years. Many of the\nobserved in-plane anisotropic properties stem from the anisotropic refractive\nindex and elastic constants of the material but a comprehensive analysis of\nthese fundamental properties is still lacking. Here we employ Raman and\nmicro-reflectance measurements, using polarized light, to determine the angular\ndependence of the refractive index of thin MoO$_3$ flakes and we study the\ndirectional dependence of the MoO$_3$ Young's modulus using the buckling\nmetrology method. We found that MoO$_3$ displays one of the largest in-plane\nanisotropic mechanical properties reported for 2D materials so far.",
        "positive": "Carbon diffusion in alpha-iron: Evidence for quantum mechanical\n  tunneling: Recent experimental data on the diffusion coefficient of carbon in alpha-iron\nbelow liquid nitrogen temperature (LNT) question the classical approach to the\nobserved temperature dependence. As the temperature is lowered below LNT, the\ndiffusion constant tends to a nearly temperature-independent value rather than\ncontinuing its activated trend. The low temperature branch is apparently\ncharacteristic of a quantum mechanical process dominated by tunneling in ground\nstate. Concommitantly, we apply an occurrence probability approach to\ndescribing the overall temperature dependence as a single continuous rate.\nWithin the adiabatic approximation the electronic eigenvalue depending\nparametrically on the nuclear coordinates is taken to be the potential energy\nto control the motion of the nuclei. The resulting rate involves all\nhorizontal-tunneling energy-conserving elastic transitions at the quantized\nenergy levels of the migrating atom. A small though not negligible slope of in\nthe temperature dependence as the temperature is raised below 100 K is dealt\nwith by complementing for the rate of a parallel one-phonon inelastic tunneling\nprocess in excess to the basic elastic-tunneling rate. Our combined approach\nagrees well with the experimental data. In particular, the frequency of the\ncoupled vibration is obtained virtually identical to the carbon vibrational\nfrequency from inelastic neutron-scattering data. The migrational barrier is\nalso found to be within the limits expected for alpha-iron."
    },
    {
        "anchor": "Miscut dependent surface evolution in the process of N-polar\n  GaN$(000\\bar 1)$ growth under N-rich condition: The evolution of surface morphology during the growth of N-polar (000-1) GaN\nunder N-rich condition is studied by kinetic Monte Carlo (kMC) simulations for\ntwo substrates miscuts 2deg and 4deg. The results are compared with\nexperimentally observed surface morphologies of (000-1) GaN layers grown by\nplasma-assisted molecular beam epitaxy. The proposed kMC two-component model of\nGaN(000-1) surface where both types of atoms: nitrogen and gallium attach the\nsurface and diffuse independently, explains that at relatively high rates of\nthe step flow (miscut angle <2deg) the low diffusion of gallium adatoms causes\nsurface instabilities and leads to experimentally observed roughening while for\nlow rates of the step flow (miscut 4deg), smooth surface can be obtained. In\nthe presence of almost immobile nitrogen atoms under N-rich conditions, the\ngrowth is realized by the process of two-dimensional island nucleation and\ncoalescence. Additionally, we show that higher crystal miscut, lower crystal\ngrowth rate or higher temperature results in similar effect of the smoothening\nof the surface. We show that the surface also smoothens for the growth\nconditions with very high N-excess. The presence of large number of nitrogen\natoms changes locally mobility of gallium atoms thus providing easier\ncoalescence of separated island.",
        "positive": "Nonreciprocal thermal transport in a multiferroic helimagnet: Breaking of spatial inversion symmetry (SIS) induces unique phenomena in\ncondensed matter. Besides the classic examples such as natural optical activity\nand piezoelectricity, the spin-orbit interaction further enriches the effect of\nSIS breaking, as exemplified by the Rashba effect. In particular, by combining\nthis symmetry with magnetic fields or another type of time-reversal symmetry\n(TRS) breaking, noncentrosymmetric materials can be made to exhibit\nnonreciprocal responses, which are responses that differ for rightward and\nleftward stimuli. For example, resistivity becomes directionally dependent;\nthat is to say, rectification appears in noncentrosymmetric materials in a\nmagnetic field. However, the effect of SIS breaking on thermal transport\nremains to be elucidated. Here we show nonreciprocal thermal transport in the\nmultiferroic helimagnet TbMnO3. The longitudinal thermal conductivity depends\non whether the thermal current is parallel or antiparallel to the vector\nproduct of the electric polarization and magnetization. This phenomenon is\nthermal rectification that is controllable with external fields in a uniform\ncrystal. This discovery may pave the way to thermal diodes with controllability\nand scalability."
    },
    {
        "anchor": "PEGylated Nano-Graphene Oxide for Delivery of Water Insoluble Cancer\n  Drugs: It is known that many potent, often aromatic drugs are water insoluble, which\nhas hampered their use for disease treatment. In this work, we functionalized\nnano-graphene oxide (NGO), a novel graphitic material, with branched\npolyethylene glycol (PEG) to obtain a biocompatible NGO-PEG conjugate stable in\nvarious biological solutions, and used them for attaching hydrophobic aromatic\nmolecules including a camptothecin (CPT) analog, SN38 non-covalently via pi-pi\nstacking. The resulting NGO-PEG-SN38 complex exhibited excellent water\nsolubility while maintaining its high cancer cell killing potency similar to\nthat of the free SN38 molecules in organic solvents. The efficacy of\nNGO-PEG-SN38 was far higher than that of irinotecan (CPT-11), a FDA approved\nwater soluble SN38 prodrug used for the treatment of colon cancer. Our results\nshowed that graphene is a novel class of material promising for biological\napplications including future in vivo cancer treatment with various aromatic,\nlow-solubility drugs.",
        "positive": "Density functional modeling of the binding energies between\n  aluminosilicate oligomers and different metal cations: Interactions between negatively charged aluminosilicate species and\npositively charged metal cations are critical to many important engineering\nprocesses and applications, including sustainable cements and aluminosilicate\nglasses. In an effort to probe these interactions, here we have calculated the\npair-wise interaction energies (i.e., binding energies) between aluminosilicate\ndimer/trimer and 17 different metal cations using a density functional theory\n(DFT) approach. Analysis of the DFT-optimized structural representations for\nthe clusters (dimer/trimer + cation) shows that their structural attributes\n(e.g., interatomic distances) are generally consistent with literature\nobservations on aluminosilicate glasses. The DFT-derived binding energies are\nseen to vary considerably depending on the type of cations (i.e., charge and\nionic radii) and aluminosilicate species (i.e., dimer or trimer). A survey of\nthe literature reveals that the difference in the calculated binding energies\nbetween different cations can be used to explain many literature observations\non the impact of cations on materials properties (e.g., glass corrosion,\nmineral dissolution, and ionic transport). Analysis of all the DFT-derived\nbinding energies reveals that the correlation between these energy values and\nthe ionic potential and field strength of the cations are well captured by 2nd\norder polynomial functions (R2 values of 0.99-1.00 are achieved for\nregressions). Given that the ionic potential and field strength of a given\nmetal cation can be readily estimated using well-tabulated ionic radii\navailable in the literature, these simple polynomial functions would enable\nrapid estimation of the binding energies of a much wider range of cations with\nthe aluminosilicate dimer/trimer, providing guidance on the design and\noptimization of sustainable cements and aluminosilicate glasses and their\nassociated applications."
    },
    {
        "anchor": "Fractional composition of large crystallite grains: a unique\n  microstructural parameter to explain conduction behavior in single phase\n  undoped microcrystalline silicon: We have studied the dark conductivity of a broad microstructural range of\nplasma deposited single phase undoped microcrystalline silicon films in a wide\ntemperature range (15 - 450K) to identify the possible transport mechanisms and\nthe interrelationship between film microstructure and electrical transport\nbehavior. Different conduction behaviors seen in films with different\nmicrostructures are explained in the context of underlying transport mechanisms\nand microstructural features, for above and below room temperature\nmeasurements. Our microstructural studies have shown that different ranges of\nthe percentage volume fraction of the constituent large crystallite grains\n(Fcl) of the microcrystalline silicon films correspond to characteristically\ndifferent and specific microstructures, irrespective of deposition conditions\nand thicknesses. Our electrical transport studies demonstrate that each type of\nmicrocrystalline silicon material having a different range of Fcl shows\ndifferent electrical transport behaviors.",
        "positive": "Elastic trapping of dislocation loops in cascades in ion-irradiated\n  tungsten foils: Using _in situ_ transmission electron microscopy (TEM), we have observed\nnanometre scale dislocation loops formed when an ultra-high-purity tungsten\nfoil is irradiated with a very low fluence of self-ions. Analysis of the TEM\nimages has revealed the largest loops to be predominantly of prismatic 1/2<111>\ntype and of vacancy character. The formation of such dislocation loops is\nsurprising since isolated loops are expected to be highly mobile, and should\nescape from the foil. In this work we show that the observed size and number\ndensity of loops can be explained by the fact that the loops are _not_ isolated\n- the loops formed in close proximity in the cascades interact with each other\nand with vacancy clusters, also formed in cascades, through long-range elastic\nfields, which prevent the escape of loops from the foil. We find that\nexperimental observations are well reproduced by object Kinetic Monte Carlo\nsimulations of evolution of cascades _only_ if elastic interaction between the\nloops is taken into account. Our analysis highlights the profound effect of\nelastic interaction between defects on the microstructural evolution of\nirradiated materials."
    },
    {
        "anchor": "Suppressing Kirkendall Void Density in Circuit Interconnections by\n  Strain Annealing: Unpredictable Kirkendall void formation at the interface of circuit\ninterconnections underlies degradation in electronics, yet there is a lack of\neffective approaches to curb the amount of these voids. Here we developed a\nstrain-anneal method to tailor grain size distributions in the copper substrate\nof interconnections, and demonstrate quantitatively that not only the removal\nof the impurities but also an increase in the grain size of the substrates\nleads to an appreciable decline in the void density. The interconnections on\nthe substrate recrystallized at a high annealing temperature show the massive\nporosity and the increased sensitivity of the voiding to the grain size. Our\nfindings have broad implications for manipulation of void propensity in many\nother hetero-interfaces and are essential for high-performance circuit bonding\nin high temperature/high power electronic devices based on wide band gap\nsemiconductors.",
        "positive": "Mg-Ni-H films as selective coatings: tunable reflectance by layered\n  hydrogenation: Unlike other switchable mirrors, Mg2NiHx films show large changes in\nreflection that yield very low reflectance (high absorptance) at different\nhydrogen contents, far before reaching the semiconducting state. The resulting\nreflectance patterns are of interference origin, due to a self-organized\nlayered hydrogenation mechanism that starts at the substrate interface, and can\ntherefore be tuned by varying the film thickness. This tunability, together\nwith the high absorptance contrast observed between the solar and the thermal\nenergies, strongly suggests the use of these films in smart coatings for solar\napplications."
    },
    {
        "anchor": "Electron-Transport Properties of Na Nanowires under Applied Bias\n  Voltages: We present first-principles calculations on electron transport through Na\nnanowires at finite bias voltages. The nanowire exhibits a nonlinear\ncurrent-voltage characteristic and negative differential conductance. The\nlatter is explained by the drastic suppression of the transmission peaks which\nis attributed to the electron transportability of the negatively biased plinth\nattached to the end of the nanowire. In addition, the finding that a voltage\ndrop preferentially occurs on the negatively biased side of the nanowire is\ndiscussed in relation to the electronic structure and conduction.",
        "positive": "Unravelling the origin of piezo/ferro-electric properties of\n  metal-organic frameworks (MOFs) nanocrystals: Metal-organic framework (MOF) UiO-66 nanocrystals were previously believed to\nbe piezo/ferro-electrically inactive because of their centrosymmetric lattice\nsymmetries (Fm-3m (225)) revealed by Powder X-ray diffraction. However, via\ndelicate dual AC resonance tracking piezoresponse force microscopy and\npiezoresponse force spectroscopy characterizations, our nanoscale probing for\nthe first time demonstrate that UiO-66 nanocrystals show piezo/ferro-electric\nresponse. Our compelling experimental and theoretically analyses disclose that\nthe structure of UiO-66 should not be the highly centrosymmetric Fm-3m (225)\nbut a reduced symmetry form instead. UiO-66(Hf)-type MOFs possess stronger\npiezoresponse and better ferroelectric switching behaviours than their\ncounterparts UiO-66 (Zr)-type MOFs. Our study not only enriches the structural\nunderstanding of UiO-66 MOF, but also suggests possible modification of\nelectronic property of the MOFs by judicious selection of metal ions and\nfunctional ligands."
    },
    {
        "anchor": "Hydrogen embrittlement controlled by reaction of dislocation with grain\n  boundary in alpha-iron: Hydrogen atoms absorbed by metals in the hydrogen-containing environments can\nlead to the premature fracture of the metal components used in load-bearing\nconditions. Since metals used in practice are mostly polycrystalline, grain\nboundaries (GBs) can play an important role in hydrogen embrittlement of\nmetals. Here we show that the reaction of GB with lattice dislocations is a key\ncomponent in hydrogen embrittlement mechanism for polycrystalline metals. We\nuse atomistic modeling methods to investigate the mechanical response of GBs in\nalpha-iron with various hydrogen concentrations. Analysis indicates that\ndislocations impingement and emission on the GB cause the GB to locally\ntransform into an activated state with a more disordered atomistic structure,\nand introduce a local stress concentration. The activation of the GB segregated\nwith hydrogen atoms can greatly facilitate decohesion of the GB. We show that\nthe hydrogen embrittlement model proposed here can give better explanation of\nmany experimental observations.",
        "positive": "Graphene formed on SiC under various environments: Comparison of Si-face\n  and C-face: The morphology of graphene on SiC {0001} surfaces formed in various\nenvironments including ultra-high vacuum, 1 atm of argon, and 10^-6 to 10^-4\nTorr of disilane is studied by atomic force microscopy, low-energy electron\nmicroscopy, and Raman spectroscopy. The graphene is formed by heating the\nsurface to 1100 - 1600 C, which causes preferential sublimation of the Si\natoms. The argon atmosphere or the background of disilane decreases the\nsublimation rate so that a higher graphitization temperature is required, thus\nimproving the morphology of the films. For the (0001) surface, large areas of\nmonolayer-thick graphene are formed in this way, with the size of these areas\ndepending on the miscut of the sample. Results on the (000-1) surface are more\ncomplex. This surface graphitizes at a lower temperature than for the (0001)\nsurface and consequently the growth is more three-dimensional. In an atmosphere\nof argon the morphology becomes even worse, with the surface displaying\nmarkedly inhomogeneous nucleation, an effect attributed to unintentional\noxidation of the surface during graphitization. Use of a disilane environment\nfor the (000-1) surface is found to produce improved morphology, with\nrelatively large areas of monolayer-thick graphene."
    },
    {
        "anchor": "On hydrogen bond correlations at high pressures: In situ high pressure neutron diffraction measured lengths of O H and H O\npairs in hydrogen bonds in substances are shown to follow the correlation\nbetween them established from 0.1 MPa data on different chemical compounds. In\nparticular, the conclusion by Nelmes et al that their high pressure data on ice\nVIII differ from it is not supported. For compounds in which the O H stretching\nfrequencies red shift under pressure, it is shown that wherever structural data\nis available, they follow the stretching frequency versus H O (or O O) distance\ncorrelation. For compounds displaying blue shifts with pressure an analogy\nappears to exist with improper hydrogen bonds.",
        "positive": "Unravelling Single Atom Catalysis: The Surface Science Approach: Understanding the fundamental mechanisms of single-atom catalysis (SAC) is\nimportant to design systems with improved performance and stability. This is\nproblematic, however, because single-atom active sites are extremely difficult\nto characterize with existing experimental techniques. Over the last 40 years,\nsurface science has provided the fundamental insights to understand\nheterogeneous catalysis, but model systems in which metal atoms are stable on\nwell-characterized metal-oxide substrates at reaction temperatures are scarce.\nIn this perspective, I discuss what is already known about isolated metal atoms\nadsorbed on model metal-oxide surfaces, and how this information can be used to\nunderstand SAC. A key issue is that, although the highly-idealised model\nsystems studied in surface science may not be representative of a real working\ncatalyst, they do very much resemble what can be calculated using\nstate-of-the-art theoretical modelling. Thus, surface science offers an\nopportunity to rigorously benchmark the theoretical approach to modelling SAC\nin future. Perhaps more excitingly, several groups have developed model systems\nwhere metal adatoms remain stable at elevated temperatures. To date however,\nthere has been no clear demonstration of catalytic activity. The perspective\ncloses with a brief discussion of the prospect for STM experiments under\nrealistic reaction conditions."
    },
    {
        "anchor": "Amplitude Contrast Imaging in High-Resolution Transmission Electron\n  Microscopy of Ferroelectric Superlattice Film: To date, high-resolution electron microscopy has largely relied on using the\nphase of the exit wave function at the exit surface to form a high-resolution\nelectron microscopic image. We have for the first time used chromatic\naberration correction to implement a new imaging mode to achieve amplitude\ncontrast imaging in high-resolution electron microscopy, allowing us to obtain\ndirectly interpretable high-resolution electron microscopic images with\ndiscrimination between light and heavy atomic columns. Using this imaging\napproach, we have successfully visualized the atomic structure in a\nBaTiO3/CaTiO3 superlattice with high spatial accuracy and discrimination\nbetween Ba and Ca columns, providing direct visualization of the Ca and Ba\nassociated oxygen octahedral tilt that controls ferroelectric behavior in these\nsuperlattice structures. Furthermore, this approach offers new opportunities to\nunravel the structure in a wide range of materials, especially complex oxides\nwith exotic behaviors based on specific structural arrangements.",
        "positive": "Exchange Bias Effect in Au-Fe3O4 Nanocomposites: We report exchange bias (EB) effect in the Au-Fe3O4 composite nanoparticle\nsystem, where one or more Fe3O4 nanoparticles are attached to an Au seed\nparticle forming dimer and cluster morphologies, with the clusters showing much\nstronger EB in comparison with the dimers. The EB effect develops due to the\npresence of stress in the Au-Fe3O4 interface which leads to the generation of\nhighly disordered, anisotropic surface spins in the Fe3O4 particle. The EB\neffect is lost with the removal of the interfacial stress. Our atomistic\nMonte-Carlo studies are in excellent agreement with the experimental results.\nThese results show a new path towards tuning EB in nanostructures, namely\ncontrollably creating interfacial stress, and open up the possibility of tuning\nthe anisotropic properties of biocompatible nanoparticles via a controllable\nexchange coupling mechanism."
    },
    {
        "anchor": "Valley relaxation of resident electrons and holes in a monolayer\n  semiconductor: Dependence on carrier density and the role of\n  substrate-induced disorder: Using time-resolved optical Kerr rotation, we measure the low temperature\nvalley dynamics of resident electrons and holes in exfoliated WSe$_2$\nmonolayers as a systematic function of carrier density. In an effort to\nreconcile the many disparate timescales of carrier valley dynamics in monolayer\nsemiconductors reported to date, we directly compare the doping-dependent\nvalley relaxation in two electrostatically-gated WSe$_2$ monolayers having\ndifferent dielectric environments. In a fully-encapsulated structure\n(hBN/WSe$_2$/hBN, where hBN is hexagonal boron nitride), valley relaxation is\nfound to be monoexponential. The valley relaxation time $\\tau_v$ is quite long\n($\\sim$10~$\\mu$s) at low carrier densities, but decreases rapidly to less than\n100~ns at high electron or hole densities $\\gtrsim$2 $\\times\n10^{12}$~cm$^{-2}$. In contrast, in a partially-encapsulated WSe$_2$ monolayer\nplaced directly on silicon dioxide (hBN/WSe$_2$/SiO$_2$), carrier valley\nrelaxation is multi-exponential at low carrier densities. The difference is\nattributed to environmental disorder from the SiO$_2$ substrate. Unexpectedly,\nvery small out-of-plane magnetic fields can increase $\\tau_v$, especially in\nthe hBN/WSe$_2$/SiO$_2$ structure, suggesting that localized states induced by\ndisorder can play an important role in depolarizing spins and mediating the\nvalley relaxation of resident carriers in monolayer transition\nmetal-dichalcogenide semiconductors.",
        "positive": "Screening in semiconductor nanocrystals: \\textit{Ab initio} results and\n  Thomas-Fermi theory: A first-principles calculation of the impurity screening in Si and Ge\nnanocrystals is presented. We show that isocoric screening gives results in\nagreement with both the linear response and the point-charge approximations.\nBased on the present ab initio results, and by comparison with previous\ncalculations, we propose a physical real-space interpretation of the several\ncontributions to the screening. Combining the Thomas-Fermi theory and simple\nelectrostatics, we show that it is possible to construct a model screening\nfunction that has the merit of being of simple physical interpretation. The\nmain point upon which the model is based is that, up to distances of the order\nof a bond length from the perturbation, the charge response does not depend on\nthe nanocrystal size. We show in a very clear way that the link between the\nscreening at the nanoscale and in the bulk is given by the surface\npolarization. A detailed discussion is devoted to the importance of local field\neffects in the screening. Our first-principles calculations and the\nThomas-Fermi theory clearly show that in Si and Ge nanocrystals, local field\neffects are dominated by surface polarization, which causes a reduction of the\nscreening in going from the bulk down to the nanoscale. Finally, the model\nscreening function is compared with recent state-of-the-art ab initio\ncalculations and tested with impurity activation energies."
    },
    {
        "anchor": "Structural defects responsible for strain glassy transition in\n  Ni$_{50+x}$Ti$_{50-x}$: The strain glassy phase is produced by doping a small percentage of impurity\nin a martensitic alloy. Its ground state is conceived to consist of martensitic\nnano domains spatially separated from each other by a defect phase. The present\nstudy, by probing the local structure around the Ni and Ti in martensitic and\nstrain glassy compositions of Ni$_{50+x}$Ti$_{50-x}$, for the first time,\nidentifies the defect phase that is responsible for inhibiting the long range\nordering of the elastic strain vector leading to the formation of the strain\nglassy phase.",
        "positive": "Evidence for reversible control of magnetization in a ferromagnetic\n  material via spin-orbit magnetic field: Conventional computer electronics creates a dichotomy between how information\nis processed and how it is stored. Silicon chips process information by\ncontrolling the flow of charge through a network of logic gates. This\ninformation is then stored, most commonly, by encoding it in the orientation of\nmagnetic domains of a computer hard disk. The key obstacle to a more intimate\nintegration of magnetic materials into devices and circuit processing\ninformation is a lack of efficient means to control their magnetization. This\nis usually achieved with an external magnetic field or by the injection of\nspin-polarized currents. The latter can be significantly enhanced in materials\nwhose ferromagnetic properties are mediated by charge carriers. Among these\nmaterials, conductors lacking spatial inversion symmetry couple charge currents\nto spin by intrinsic spin-orbit (SO) interactions, inducing nonequilibrium spin\npolarization tunable by local electric fields. Here we show that magnetization\nof a ferromagnet can be reversibly manipulated by the SO-induced polarization\nof carrier spins generated by unpolarized currents. Specifically, we\ndemonstrate domain rotation and hysteretic switching of magnetization between\ntwo orthogonal easy axes in a model ferromagnetic semiconductor."
    },
    {
        "anchor": "Weyl-like points from band inversions of spin-polarised surface states\n  in NbGeSb: Band inversions are key to stabilising a variety of novel electronic states\nin solids, from topological surface states in inverted bulk band gaps of\ntopological insulators to the formation of symmetry-protected three-dimensional\nDirac and Weyl points and nodal-line semimetals. Here, we create a band\ninversion not of bulk states, but rather between manifolds of surface states.\nWe realise this by aliovalent substitution of Nb for Zr and Sb for S in the\nZrSiS family of nonsymmorphic semimetals. Using angle-resolved photoemission\nand density-functional theory, we show how two pairs of surface states, known\nfrom ZrSiS, are driven to intersect each other in the vicinity of the Fermi\nlevel in NbGeSb, as well as to develop pronounced spin-orbit mediated spin\nsplittings. We demonstrate how mirror symmetry leads to protected crossing\npoints in the resulting spin-orbital entangled surface band structure, thereby\nstabilising surface state analogues of three-dimensional Weyl points. More\ngenerally, our observations suggest new opportunities for engineering\ntopologically and symmetry-protected states via band inversions of surface\nstates.",
        "positive": "Mechanical properties of Graphene Nanoribbons: Herein, we investigate the structural, electronic and mechanical properties\nof zigzag graphene nanoribbons upon the presence of stress applying Density\nFunctional Theory within the GGA-PBE approximation. The uniaxial stress is\napplied along the periodic direction, allowing a unitary deformation in the\nrange of +/- 0.02%. The mechanical properties show a linear-response within\nthat range while the non-linear dependence is found for higher strain. The most\nrelevant results indicate that Young's modulus is considerable higher than\nthose determined for graphene and carbon nanotubes. The geometrical\nreconstruction of the C-C bonds at the edges hardness the nanostructure.\nElectronic structure features are not sensitive to strain in this linear\nelastic regime, being an additional promise for the using of carbon\nnanostructures in nano-electronic devices in the near future."
    },
    {
        "anchor": "Magnetodielectric Coupling in Nonmagnetic Au/GaAs:Si Schottky Barriers: We report on a heretofore unnoted giant negative magnetocapacitance (>20%) in\nnon-magnetic Au/GaAs:Si Schottky barriers that we attribute to a magnetic field\nin-duced increase in the binding energy of the shallow donor Si impurity atoms.\nDepletion capacitance (Cdep) dispersion identifies the impurity ionization and\ncapture processes that give rise to a magnetic field dependent density of\nionized impurities. Internal photoemission experiments confirm that the large\nfield-induced shifts in the built-in potential, inferred from 1/Cdep^2 vs\nvoltage measurements, are not due to a field-dependent Schottky barrier height,\nthus requiring a modification of the abrupt junction approximation that\naccounts for the observed magnetodielectric coupling.",
        "positive": "Electron-vibrational interaction in the 5d states of Eu2+ ions in\n  Sr6-xEuxBP5O20 (x=0.01; 0.03; 0.05; 0.07; 0.09; 0.11; 0.13; 0.15): In the present paper we report on the combined experimental and theoretical\nstudy of the Sr6-xEuxBP5O20 (x=0.01; 0.03; 0.05; 0.07; 0.09; 0.11; 0.13; 0.15)\nphosphors. Details of the samples preparation and spectroscopic measurements\nare followed by the analysis of the room-temperature absorption and emission\nspectra, which yielded the main parameters of the electron-phonon coupling,\nsuch as Huang-Rhys factor, Stokes shift, effective phonon energy, and\nzero-phonon line position were determined for the first time for the studied\nsystem. The obtained parameters were used to model the emission band shapes,\nwhich perfectly reproduce the experimental results for all samples."
    },
    {
        "anchor": "Strain analysis based on EAM and applications on surface, vacancy, and\n  boundary of Al: Stress or strain analysis for each atom around structural defects in a\ncrystal is difficult. We propose a new analytical approach based on the eminent\nEmbedding Atom Method(EAM) potential. We observe that the ratio $R$ between the\nrepulsive and binding terms of the EAM is a definite measure for calculating\nthe strain field of a single atom subject to an irregular coordination number.\nThe determination of adequate potential parameters and their application to the\ncalculation of the properties of surface, vacancy, and boundary of pure Al are\nshown.",
        "positive": "Gauge-Invariant Measure of the Magnon Orbital Angular Momentum: Unlike the Berry phase, the orbital angular momentum (OAM) of magnons with\ntwo-dimensional wavevector k in band n is not gauge invariant for arbitrary\nphase lambda_n(k). However, by integrating the OAM over the orientation $\\phi $\nof wavevector k, we construct a gauge-invariant function F_n(k). Like F_n(k),\nthe average OAM for magnon band n in a circle of radius k is also gauge\ninvariant. We demonstrate these results for a ferromagnet on a honeycomb\nlattice with Dzyalloshinskii-Moriya interactions between next-nearest neighbor\nspins. With wavevectors k restricted to the first Brillouin zone, the angular\naveraged OAM F_n(k) then has opposite signs for lower and upper bands n=1 and 2\nfor all k."
    },
    {
        "anchor": "First-principles study of lattice dynamical properties of the\n  room-temperature $P2_1/n$ and ground-state $P2_1/c$ phases of WO$_3$: Using first-principles density functional theory, we investigate the\ndynamical properties of the room-temperature $P2_1/n$ and ground-state $P2_1/c$\nphases of WO$_3$. As a preliminary step, we assess the validity of various\nstandard and hybrid functionals, concluding that the best description is\nachieved with the B1-WC hybrid functional while a reliable description can also\nbe provided using the standard LDA functional. We also carefully rediscuss the\nstructure and energetics of all experimentally observed and a few hypothetical\nmetastable phases in order to provide deeper insight into the unusual phase\ndiagram of WO$_3$. Then, we provide a comprehensive theoretical study of the\nlattice dynamical properties of the $P2_1/n$ and $P2_1/c$ phases, reporting\nzone-center phonons, infrared and Raman spectra as well as the full phonon\ndispersion curves, which attest for the dynamical stability of both phases. We\ncarefully discuss the spectra, explaining the physical origin of their main\nfeatures and evolution from one phase to another. We reveal a systematic\nconnection between the dynamical and structural properties of WO$_3$,\nhighlighting that the number of peaks in the high-frequency range of the Raman\nspectrum appears as a fingerprint of the number of antipolar distortions that\nare present in the structure and a practical way to discriminate between the\ndifferent phases.",
        "positive": "A generalized 3D elastic model for nanoscale, self-assembled oxide-metal\n  thin films with pillar-in-matrix configurations: In recent years, functional oxide-metal based vertically aligned\nnanocomposite (VAN) thin films have gained interest due to their intriguing\nphysical properties and multifunctionalities stemming from the complex\ninteractions between the two phases in the film and the substrate. In this\nwork, we develop a model for studying the energetics of these thin film\nsystems, including the effects of both lattice mismatch and capillary forces\ndue to interface curvature. Each phase is incorporated into the model using a\nphase indicator function, and we introduce the capillary forces as body forces\nusing a vector density representation of the interface. The model is\nimplemented using the finite element method to study the deformation of the\nthin film which is composed of Au nanopillars embedded in a La0.7Sr0.3MnO3\n(LSMO) matrix on an SrTiO3 (STO) substrate. The results suggest that the total\nenergy is lowest for random configurations of pillars compared to ordered\nsquare and hexagonal lattice configurations, consistent with the random\ndistribution of pillars found in experiments. Furthermore, we find that the\ninterfacial energy dominates the total energy of each configuration, suggesting\nthat interfacial energy in the system is an important design parameter for\nnanocomposite growth, along with the lattice mismatch."
    },
    {
        "anchor": "Hyperferroelectrics: proper ferroelectrics with persistent polarization: All known proper ferroelectrics are unable to polarize normal to a surface or\ninterface if the resulting depolarization field is unscreened, but there is no\nfundamental principle that enforces this behavior. In this work, we introduce\nhyperferroelectrics, a new class of proper ferroelectrics which polarize even\nwhen the depolarization field is unscreened, this condition being equivalent to\ninstability of a longitudinal optic mode in addition to the\ntransverse-optic-mode instability characteristic of proper ferroelectrics. We\nuse first principles calculations to show that several recently discovered\nhexagonal ferroelectric semiconductors have this property, and we examine its\nconsequences both in the bulk and in a superlattice geometry.",
        "positive": "A hybrid algorithm for parallel molecular dynamics simulations: This article describes algorithms for the hybrid parallelization and SIMD\nvectorization of molecular dynamics simulations with short-range forces. The\nparallelization method combines domain decomposition with a thread-based\nparallelization approach. The goal of the work is to enable efficient\nsimulations of very large (tens of millions of atoms) and inhomogeneous systems\non many-core processors with hundreds or thousands of cores and SIMD units with\nlarge vector sizes. In order to test the efficiency of the method, simulations\nof a variety of configurations with up to 74 million atoms have been performed.\nResults are shown that were obtained on multi-core systems with Sandy Bridge\nand Haswell processors as well as systems with Xeon Phi many-core processors."
    },
    {
        "anchor": "Strain gradient plasticity-based modeling of hydrogen environment\n  assisted cracking: Finite element analysis of stress about a blunt crack tip, emphasizing finite\nstrain and phenomenological and mechanism-based strain gradient plasticity\n(SGP) formulations, is integrated with electrochemical assessment of\noccluded-crack tip hydrogen (H) solubility and two H-decohesion models to\npredict hydrogen environment assisted crack growth properties. SGP elevates\ncrack tip geometrically necessary dislocation density and flow stress, with\nenhancement declining with increasing alloy strength. Elevated hydrostatic\nstress promotes high-trapped H concentration for crack tip damage; it is\nimperative to account for SGP in H cracking models. Predictions of the\nthreshold stress intensity factor and H-diffusion limited Stage II crack growth\nrate agree with experimental data for a high strength austenitic Ni-Cu\nsuperalloy (Monel K-500) and two modern ultra-high strength martensitic steels\n(AerMet 100 and Ferrium M54) stressed in 0.6 M NaCl solution over a range of\napplied potential. For Monel K-500, KTH is accurately predicted versus cathodic\npotential using either classical or gradient-modified formulations; however,\nStage II growth rate is best predicted by a SGP description of crack tip stress\nthat justifies a critical distance of 1 {\\mu}m. For steel, threshold and growth\nrate are best predicted using high-hydrostatic stress that exceeds 6 to 8 times\nalloy yield strength and extends 1 {\\mu}m ahead of the crack tip. This stress\nis nearly achieved with a three-length phenomenological SGP formulation, but\nadditional stress enhancement is needed, perhaps due to tip geometry or\nslip-microstructure.",
        "positive": "Interaction between U/UO2 bilayers and hydrogen studied by in-situ X-ray\n  diffraction: This paper reports experiments investigating the reaction of H$_{2}$ with\nuranium metal-oxide bilayers. The bilayers consist of $\\leq$ 100 nm of\nepitaxial $\\alpha$-U (grown on a Nb buffer deposited on sapphire) with a\nUO$_{2}$ overlayer of thicknesses of between 20 and 80 nm. The oxides were made\neither by depositing via reactive magnetron sputtering, or allowing the uranium\nmetal to oxidise in air at room temperature. The bilayers were exposed to\nhydrogen, with sample temperatures between 80 and 200 C, and monitored via\nin-situ x-ray diffraction and complimentary experiments conducted using\nScanning Transmission Electron Microscopy - Electron Energy Loss Spectroscopy\n(STEM-EELS). Small partial pressures of H$_{2}$ caused rapid consumption of the\nU metal and lead to changes in the intensity and position of the diffraction\npeaks from both the UO$_{2}$ overlayers and the U metal. There is an\norientational dependence in the rate of U consumption. From changes in the\nlattice parameter we deduce that hydrogen enters both the oxide and metal\nlayers, contracting the oxide and expanding the metal. The air-grown oxide\noverlayers appear to hinder the H$_{2}$-reaction up to a threshold dose, but\nthen on heating from 80 to 140 C the consumption is more rapid than for the\nas-deposited overlayers. STEM-EELS establishes that the U-hydride layer lies at\nthe oxide-metal interface, and that the initial formation is at defects or\ngrain boundaries, and involves the formation of amorphous and/or\nnanocrystalline UH$_{3}$. This explains why no diffraction peaks from UH$_{3}$\nare observed. {\\textcopyright British Crown Owned Copyright 2017/AWE}"
    },
    {
        "anchor": "Percolative Effects on Noise in Pentacene Transistors: The 1/f noise in pentacene thin film transistors has been measured as a\nfunction of device thickness from well above the effective conduction channel\nthickness to only two conducting layers. Over the entire thickness range, the\nspectral noise form is 1/f, and the noise parameter varies as (gate voltage)-1,\nconfirming that the noise is due to mobility fluctuations, even in the thinnest\nfilms. Hooge's parameter varies as an inverse power-law with conductivity for\nall film thicknesses. The magnitude and transport characteristics of the\nspectral noise are well explained in terms of percolative effects arising from\nthe grain boundary structure.",
        "positive": "Electronic and optical properties of Cr and Cr-N doped anatase TiO2 from\n  screened Coulomb hybrid calculations: We studied the electronic and atomic structures of anatase TiO2 codoped with\nCr and N using hybrid density functional theory calculations. Nonlocal screened\nHartree-Fock exchange energy is partially mixed with traditional semilocal\nexchange part. This not only heals the band gap underestimation but also\nimproves the description of anion/cation-driven impurity states and\nmagnetization of the dopants. Cr and/or N doping modifies the valence and\nconduction band edges of TiO2 leading to significant band gap reduction. Hence,\nCr, N and Cr-N doped TiO2 are promising for enhanced photoactivity."
    },
    {
        "anchor": "Determination of the local concentrations of Mn interstitials and\n  antisite defects in GaMnAs: We present a method for the determination of the local concentrations of\ninterstitial and substitutional Mn atoms and As antisite defects in GaMnAs. The\nmethod relies on the sensitivity of the structure factors of weak reflections\nto the concentrations and locations of these minority constituents. High\nspatial resolution is obtained by combining structure factor measurement and\nX-ray analysis in a transmission electron microscope. We demonstrate the\nprevalence of interstitials with As nearest neighbors in as-grown layers.",
        "positive": "Modeling Heat Dissipation at the Nanoscale: An Embedding Approach for\n  Chemical Reaction Dynamics on Metal Surfaces: We present an embedding technique for metallic systems that makes it possible\nto model energy dissipation into substrate phonons during surface chemical\nreactions from first principles. The separation of chemical and elastic\ncontributions to the interaction potential provides a quantitative description\nof both electronic and phononic band structure. Application to the dissociation\nof O$_2$ at Pd(100) predicts translationally \"hot\" oxygen adsorbates as a\nconsequence of the released adsorption energy (ca. 2.6 eV). This finding\nquestions the instant thermalization of reaction enthalpies generally assumed\nin models of heterogeneous catalysis."
    },
    {
        "anchor": "Optical spectroscopy on the photo-response in multiferroic BiFeO$_3$ at\n  high pressure: The pressure dependence of light-induced effects in single-crystalline\nBiFeO$_3$ is studied by optical spectroscopy. At low pressures, we observe\nthree light-induced absorption features with energies just below the two\ncrystal field excitations and the absorption onset, respectively. These\nabsorption features were previously ascribed to excitons, possibly connected\nwith the ultra-fast photostriction effect in BiFeO$_3$. The pressure-induced\nredshift of the absorption features follows the pressure dependence of the\ncorresponding crystal field excitations and absorption onset, suggesting the\nlink between them. Above the structural phase transition at\n$P_{\\mathrm{c1}}\\approx{}3.5$ GPa the three absorption features disappear,\nsuggesting their connection to the polar phase in BiFeO$_3$. The\npressure-induced disappearance of the photo-induced features is irreversible\nupon pressure release.",
        "positive": "Deciphering structural and magnetic disorder in the chiral skyrmion host\n  materials Co$_x$Zn$_y$Mn$_z$ ($x+y+z=20$): Co$_x$Zn$_y$Mn$_z$ ($x+y+z=20$) compounds crystallizing in the chiral\n$\\beta$-Mn crystal structure are known to host skyrmion spin textures even at\nelevated temperatures. As in other chiral cubic skyrmion hosts, skyrmion\nlattices in these materials are found at equilibrium in a small pocket just\nbelow the magnetic Curie temperature. Remarkably, CoxZnyMnz compounds have also\nbeen found to host metastable non-equilibrium skyrmion lattices in a broad\ntemperature and field range, including down to zero-field and low temperature.\nThis behavior is believed to be related to disorder present in the materials.\nHere, we use neutron and synchrotron diffraction, density functional theory\ncalculations, and DC and AC magnetic measurements, to characterize the atomic\nand magnetic disorder in these materials. We demonstrate that Co has a strong\nsite-preference for the diamondoid 8c site in the crystal structure, while Mn\ntends to share the geometrically frustrated 12d site with Zn, due to its\nability to develop a large local moment on that site. This magnetism-driven\nsite specificity leads to distinct magnetic behavior for the Co-rich 8c\nsublattice and the Mn on the 12d sublattice. The Co-rich sublattice orders at\nhigh temperatures (compositionally tunable between 100K to 470K) with a moment\naround 1 $\\mu_B$/atom and maintains this order to low temperature. The Mn-rich\nsublattice holds larger moments (about 3 $\\mu_B$ which remain fluctuating below\nthe Co moment ordering temperature. At lower temperature, the fluctuating Mn\nmoments freeze into a reentrant disordered cluster-glass state with no net\nmoment, while the Co moments maintain order. This two-sublattice behavior\nallows for the observed coexistence of strong magnetic disorder and ordered\nmagnetic states such as helimagnetism and skyrmion lattices."
    },
    {
        "anchor": "Ferroelectricity and topological vortices from molecular ordering in\n  metal-organic frameworks: Metal-organic frameworks comprehend a wide class of hybrid organic-inorganic\nmaterials with general structure A$_m$BX$_n$, with $A$ and $X$ being organic\nmolecules and B a metal cation. This often results in enhanced structural\nflexibility and new functionalities. Hybrid perovskites ABX$_3$ are a\nwell-known example.} In an Iron-based perovskites, (DMA)Fe^{II-III}(COOH)_3,\ndimethylammonium (DMA) molecules are organized in a hexagonal structure. They\nare orientationally disordered at high temperatures, but order at around\n$T=100$~K in a peculiar toroidal pattern. Recent experimental and theoretical\nstudy suggest the appearance of ferroelectric polarization in this phase,\nalthough the measured polarization is small, and the mechanism of\nferroelectricity is still debated. We formulate a Landau-type theory that\nclarifies the connection between the electric polarization, molecular pattern,\nand distortive modes of the inorganic lattice. We find a remarkable mechanism\nof improper ferroelectricity, analogue to the trimerization process in\ninorganic hexagonal ferrites and manganites, but here driven by the ordering of\norganic molecules in a metal-organic framework. Our study reveals an extremely\nrich phase diagram with the prediction of topological domain walls, where the\nferroelectricity arise from tripling the unit cells due to molecular ordering.\nWide domain walls with inner structure are predicted.",
        "positive": "Molecular potentials for 2D molybdenum disulphide: transferability and\n  performance: An ability of different molecular potentials to reproduce the properties of\n2D molybdenum disulphide polymorphs is examined. Structural and mechanical\nproperties, as well as phonon dispersion of the 2H, 1T and 1T' single-layer\nMoS2 (SL MoS2) phases, were obtained using density functional theory (DFT) and\nmolecular statics calculations (MS) with Stillinger-Weber, REBO, SNAP, and\nReaxFF potentials. Quantitative systematic comparison and discussion of the\nresults obtained are reported."
    },
    {
        "anchor": "Expanded Comment on: Optical Properties of Fluid Hydrogen at the\n  Transition to a Conducting State: We comment on a recent paper published by McWilliams et al claiming that\nhigh-pressure/high-temperature hydrogen is a semi-conductor or semi-metal, in\nconflict with all earlier measurements on this system which show that it is\nmetallic. We point out problems and inconsistencies and propose an alternate\ninterpretation such that their results can be compatible with the observation\nof metallic hydrogen.",
        "positive": "Vacancy Formation Energy at High Pressures in Tantalum: We have computed the variation of the vacancy formation energy with pressure\nfor Ta. Total energy calculations were performed for 16 and 54 atom supercells\nusing a mixed basis pseudopotential method which uses pseudo-atomic orbitals\nand low energy plane waves as the basis set, within density functional theory\n(LDA and GGA). The vacancy formation energy is found to increase from 2.95 eV\nat ambient pressures to 6.96 eV at 300 GPa, and the vacancy formation volume\ndecreases from being 53.4% of the bulk volume per atom at ambient pressure to\n19.6% at 300 GPa, for a 54 atom supercell. The structural relaxation energy is\nfound to increase with pressure from 14% of the vacancy formation energy at\nambient pressure to 16% at 300 GPa."
    },
    {
        "anchor": "Ab-initio study of the energy competition between \u0393and K valleys\n  in bilayer transition metal dichalcogenides: Moir\\'e engineering in two-dimensional van der Waals bilayer crystals has\nemerged as a flexible platform for controlling strongly correlated electron\nsystems. The competition between valleys for the band extremum energy position\nin the parent layers is crucial in deciding the qualitative nature of the\nmoir\\'e Hamiltonian since it controls the physics of the moir\\'e minibands.\nHere we use density functional theory to examine the competition between K and\n$\\Gamma$ for the valence band maximum in homo- and hetero-bilayers formed from\nthe transition metal dichalcogenides (TMD), MX\\{_2} where M=Mo,W and X=S,Se,Te.\nWe shed light on how the competition is influenced by interlayer separation,\nwhich can be modified by applying pressure, by external gate-defined electric\nfields, and by transition metal atom d-orbital correlations. Our findings are\nrelated to several recent experiments, and contribute to the development of\ndesign rules for moir\\'{e} materials.",
        "positive": "Coherent coupling between surface plasmons and excitons in semiconductor\n  nanocrystals: We present an experimental demonstration of strong coupling between a surface\nplasmon propagating on a planar silver substrate, and the lowest excited state\nof CdSe nanocrystals. Variable-angle spectroscopic ellipsometry measurements\ndemonstrated the formation of plasmon-exciton mixed states, characterized by a\nRabi splitting of $\\sim$ 82 meV at room temperature. Such a coherent\ninteraction has the potential for the development of plasmonic non-linear\ndevices, and furthermore, this system is akin to those studied in cavity\nquantum electrodynamics, thus offering the possibility to study the regime of\nstrong light-matter coupling in semiconductor nanocrystals at easily accessible\nexperimental conditions."
    },
    {
        "anchor": "Theoretical determination of the necessary conditions for the formation\n  of ZnO nanorings and nanohelices: The formation of ZnO nanorings and nanohelices with large polar surfaces\nobserved in experiments [Nano Lett. 3, 1625 (2003); J. Am. Chem. Soc. 126, 6703\n(2004)] is shown to be a result of the competition between elastic energy,\nspontaneous polarization-induced surface energy, volume energy, and\ndefect-induced energy. It is found that nanorings and nanohelices observed in\nexperiments are stable and energetically favorable structures.",
        "positive": "First-principles characterization of thermal conductivity in LaPO4-based\n  alloys: Alloys based on lanthanum phosphate (LaPO$_{4}$) are often employed as\nthermal barrier coatings, due to their low thermal conductivity and structural\nstability over a wide temperature range. To enhance the thermal-insulation\nperformance of these alloys, it is essential to comprehensively understand the\nfundamental physics governing their heat conduction. Here, we employ the Wigner\nformulation of thermal transport in conjunction with first-principles\ncalculations to elucidate how the interplay between anharmonicity and\ncompositional disorder determines the thermal properties of\nLa$_x$Gd$_{1{-}x}$PO$_{4}$ alloys, and discuss the fundamental physics\nunderlying the emergence and coexistence of particle-like and wave-like\nheat-transport mechanisms. Our predictions for microscopic vibrational\nproperties (temperature-dependent Raman spectrum) and for macroscopic thermal\nconductivity are validated against experiments. Finally, we leverage these\nfindings to devise strategies to optimize the performance of thermal barrier\ncoatings."
    },
    {
        "anchor": "In-surface confinement of topological insulator nanowire surface states: The bandstructures of [110] and [001] Bi2Te3 nanowires are solved with the\natomistic 20 band tight binding functionality of NEMO5. The theoretical results\nreveal: The popular assumption that all topological insulator wire surfaces are\nequivalent is inappropriate. The Fermi velocity of chemically distinct wire\nsurfaces differs significantly which creates an effective in-surface\nconfinement potential. As a result, topological insulator surface states prefer\nspecific surfaces. Therefore, experiments have to be designed carefully not to\nprobe surfaces unfavorable to the surface states (low density of states) and\nthereby be insensitive to the TI-effects.",
        "positive": "Nodal lines in momentum space: topological invariants and recent\n  realizations in photonic and other systems: Topological insulators constitute one of the most intriguing phenomena in\nmodern condensed matter theory. The unique and exotic properties of topological\nstates of matter allow for unidirectional gapless electron transport and\nextremely accurate measurements of the Hall conductivity. Recently, new\ntopological effects occurring at Dirac/Weyl points have been better understood\nand demonstrated using artificial materials such as photonic and phononic\ncrystals, metamaterials and electrical circuits. In comparison, the topological\nproperties of nodal lines, which are one-dimensional degeneracies in momentum\nspace, remain less explored. Here, we explain the theoretical concept of\ntopological nodal lines and review recent and ongoing progress using artificial\nmaterials. The review includes recent demonstrations of non-Abelian topological\ncharges of nodal lines in momentum space and examples of nodal lines realized\nin photonic and other systems. Finally, we will address the challenges involved\nin both experimental demonstration and theoretical understanding of topological\nnodal lines."
    },
    {
        "anchor": "Simulations of energetic beam deposition: from picoseconds to seconds: We present a new method for simulating crystal growth by energetic beam\ndeposition. The method combines a Kinetic Monte-Carlo simulation for the\nthermal surface diffusion with a small scale molecular dynamics simulation of\nevery single deposition event. We have implemented the method using the\neffective medium theory as a model potential for the atomic interactions, and\npresent simulations for Ag/Ag(111) and Pt/Pt(111) for incoming energies up to\n35 eV. The method is capable of following the growth of several monolayers at\nrealistic growth rates of 1 monolayer per second, correctly accounting for both\nenergy-induced atomic mobility and thermal surface diffusion. We find that the\nenergy influences island and step densities and can induce layer-by-layer\ngrowth. We find an optimal energy for layer-by-layer growth (25 eV for Ag),\nwhich correlates with where the net impact-induced downward interlayer\ntransport is at a maximum. A high step density is needed for energy induced\nlayer-by-layer growth, hence the effect dies away at increased temperatures,\nwhere thermal surface diffusion reduces the step density. As part of the\ndevelopment of the method, we present molecular dynamics simulations of single\natom-surface collisions on flat parts of the surface and near straight steps,\nwe identify microscopic mechanisms by which the energy influences the growth,\nand we discuss the nature of the energy-induced atomic mobility.",
        "positive": "Manipulating of magnetism in the topological semimetal EuCd2As2: Magnetic Weyl semimetals are expected to have extraordinary physical\nproperties such as a chiral anomaly and large anomalous Hall effects that may\nbe useful for future, potential, spintronics applications. However, in most\nknown host materials, multiple pairs of Weyl points prevent a clear\nmanifestation of the intrinsic topological effects. Our recent density\nfunctional theory (DFT) calculations study suggest that EuCd$_{2}$As$_{2}$ can\nhost Dirac fermions in an antiferromagnetically (AFM) ordered state or a single\npair of Weyl fermions in a ferromagnetically (FM) ordered state. Unfortunately,\npreviously synthesized crystals ordered antiferromagnetically with\n$T_{\\textrm{N}}$\\,$\\simeq$\\,9.5\\,K. Here, we report the successful synthesis of\nsingle crystals of EuCd$_{2}$As$_{2}$ that order ferromagnetically (FM) or\nantiferromagnetically (AFM) depending on the level of band filling, thus\nallowing for the use of magnetism to tune the topological properties within the\nsame host. We explored their physical properties via magnetization, electrical\ntransport, heat capacity, and angle resolved photoemission spectroscopy (ARPES)\nmeasurements and conclude that EuCd$_{2}$As$_{2}$ is an excellent, tunable,\nsystem for exploring the interplay of magnetic ordering and topology."
    },
    {
        "anchor": "Superconductivity at epitaxial LaTiO3-KTaO3 interfaces: Design of epitaxial interfaces is a pivotal way to engineer artificial\nstructures where new electronic phases can emerge. Here we report a systematic\nemergence of interfacial superconducting state in epitaxial heterostructures of\nLaTiO3 and KTaO3. The superconductivity transition temperature increases with\ndecreasing the thickness of LaTiO3. Such behavior is observed for both (110)\nand (111) crystal oriented structures. For thick samples, the finite resistance\ndeveloping below the superconducting transition temperature increases with\nincreasing LaTiO3 thickness. Consistent with previous reports, the (001)\noriented heterointerface features high electron mobility of 250 cm2/Vs and\nshows no superconducting transition down to 40 mK. Our results imply a\nnon-trivial impact of LaTiO3 on the superconducting state and indicate how\nsuperconducting KTaO3 interfaces can be integrated with other oxide materials.",
        "positive": "Anisotropic linear and nonlinear charge-spin conversion in topological\n  semimetal SrIrO3: Over the past decade, utilizing spin currents in the linear response of\nelectric field to manipulate magnetization states via spin-orbit torques (SOTs)\nis one of the core concepts for realizing a multitude of spintronic devices.\nBesides the linear regime, recently, nonlinear charge-spin conversion under the\nsquare of electric field has been recognized in a wide variety of materials\nwith nontrivial spin textures, opening an emerging field of nonlinear\nspintronics. Here, we report the investigation of both linear and nonlinear\ncharge-spin conversion in one single topological semimetal SrIrO3(110) thin\nfilm that hosts strong spin-orbit coupling and nontrivial spin textures in the\nmomentum space. In the nonlinear regime, the observation of crystalline\ndirection dependent response indicates the presence of anisotropic surface\nstates induced spin-momentum locking near the Fermi level. Such anisotropic\nspin textures also give rise to spin currents in the linear response regime,\nwhich mainly contributes to the fieldlike SOT component. Our work demonstrates\nthe power of combination of linear and nonlinear approaches in understanding\nand utilizing charge-spin conversion in topological materials."
    },
    {
        "anchor": "Towards engineering the perfect defect in high-performing permanent\n  magnets: Permanent magnets draw their properties from a complex interplay, across\nmultiple length scales, of the composition and distribution of their\nconstituting phases, that act as building blocks, each with their associated\nintrinsic properties. Gaining a fundamental understanding of these interactions\nis hence key to decipher the origins of their magnetic performance and\nfacilitate the engineering of better-performing magnets, through unlocking the\ndesign of the \"perfect defects\" for ultimate pinning of magnetic domains. Here,\nwe deployed advanced multiscale microscopy and microanalysis on a bulk\nSm2(CoFeCuZr)17 pinning-type high-performance magnet with outstanding thermal\nand chemical stability. Making use of regions with different chemical\ncompositions, we showcase how both a change in the composition and distribution\nof copper, along with the atomic arrangements enforce the pinning of magnetic\ndomains, as imaged by nanoscale magnetic induction mapping. Micromagnetic\nsimulations bridge the scales to provide an understanding of how these\npeculiarities of micro- and nanostructure change the hard magnetic behaviour of\nSm2(CoFeCuZr)17 magnets. Unveiling the origins of the reduced coercivity allows\nus to propose an atomic-scale defect and chemistry manipulation strategy to\ndefine ways toward future hard magnets.",
        "positive": "Production of Metal-free Diamond Nanoparticles: In this paper, the controlled production of high quality metal-free diamond\nnanoparticles is demonstrated. Milling with tempered steel is shown to leave\nbehind iron oxide contamination which is difficult to remove. Milling with SiN\nalleviates this issue but generates more non diamond carbon. Thus the choice of\nmilling materials is critically determined by the acceptable contaminants in\nthe ultimate application. The removal of metal impurities, present in all\ncommercially available nanoparticles, will open new possibilities towards the\nproduction of customised diamond nanoparticles, covering the most demanding\nquantum applications."
    },
    {
        "anchor": "Tailoring negative pressure by crystal defects: Crack induced hydride\n  formation in Al alloys: Climate change motivates the search for non-carbon-emitting energy generation\nand storage solutions. Metal hydrides show promising characteristics for this\npurpose. They can be further stabilized by tailoring the negative pressure of\nmicrostructural and structural defects. Using systematic ab initio and\natomistic simulations, we demonstrate that an enhancement in the formation of\nhydrides at the negatively pressurized crack tip region is feasible by\nincreasing the mechanical tensile load on the specimen. The theoretical\npredictions have been used to reassess and interpret atom probe tomography\nexperiments for a high-strength 7XXX-aluminium alloy that show a substantial\nenhancement of hydrogen concentration at structural defects near a\nstress-corrosion crack tip. These results contain important implications for\nenhancing the capability of metals as H-storage materials.",
        "positive": "Dynamic interfaces in an organic thin film: Low-dimensional boundaries between phases and domains in organic thin films\nare important in charge transport and recombination. Here, fluctuations of\ninterfacial boundaries in an organic thin film, acridine-9-carboxylic acid\n(ACA) on Ag(111), have been visualized in real time, and measured\nquantitatively, using Scanning Tunneling Microscopy. The boundaries fluctuate\nvia molecular exchange with exchange time constants of 10-30 ms at room\ntemperature, yielding length mode fluctuations that should yield characteristic\nf-1/2 signatures for frequencies less than ~100 Hz. Although ACA has highly\nanisotropic intermolecular interactions, it forms islands that are compact in\nshape with crystallographically distinct boundaries that have essentially\nidentical thermodynamic and kinetic properties . The physical basis of the\nmodified symmetry is shown to arise from significantly different substrate\ninteractions induced by alternating orientations of successive molecules in the\ncondensed phase. Incorporating this additional set of interactions in a lattice\ngas model leads to effective multi-component behavior, as in the\nBlume-Emery-Griffiths (BEG) model, and can straightforwardly reproduce the\nexperimentally observed isotropic behavior. The general multi-component\ndescription allows the domain shapes and boundary fluctuations to be tuned from\nisotropic to highly anisotropic in terms of the balance between intermolecular\ninteractions and molecule-substrate interactions. Key words: Organic thin film,\nfluctuations, STM, molecular interactions, diffusion kinetics, phase\ncoexistence"
    },
    {
        "anchor": "Evidence of Hot Carrier Extraction in Metal Halide Perovskite Solar\n  Cells: The presence of hot carriers is presented in the operational properties of an\n(FA,Cs)Pb(I, Br, Cl)3 solar cell at ambient temperatures and under practical\nsolar concentration. At 100 K, clear evidence of hot carriers is observed in\nboth the high energy tail of the photoluminescence spectra and from the\nappearance of a non-equilibrium photocurrent at higher fluence in light J-V\nmeasurements. At room temperature, however, the presence of hot carriers in the\nemission at elevated laser fluence are shown to compete with a gradual red\nshift in the PL peak energy as photo induced halide segregation begins to occur\nat higher lattice temperature. The effects of thermionic emission of hot\ncarriers and the presence of a non-equilibrium carrier distribution are also\nshown to be distinct from simple lattice heating. This results in large\nunsaturated photocurrents at high powers as the Fermi distribution exceeds that\nof the heterointerface controlling carrier transport and rectification.",
        "positive": "4He adsorbed outside a single carbon nanotube: The phase diagrams of $^4$He adsorbed on the external surfaces of single\narmchair carbon nanotubes with radii in the range 3.42 -- 10.85 \\AA \\ are\ncalculated using the diffusion Monte Carlo method. For nanotubes narrower than\na (10,10) one, the ground state is an incommensurate solid similar to the one\nfound for H$_2$ on the same substrates. For wider nanotubes, the phase with the\nminimum energy per particle is a liquid layer. Curved $\\sqrt 3 \\times \\sqrt 3$\nregistered solids similar to the ones found on graphene and graphite were\nunstable for all the tubes considered."
    },
    {
        "anchor": "Liquid-Liquid Phase Transition in Supercooled Silicon: We present a review on the study of metastable silicon, primarily focusing\nmainly on the aspects of liquid-liquid transition, critical point and phase\nbehaviour, structural and dynamic properties of liquid phase as well as crystal\nnucleation. We begin with an extensive survey of the investigations of liquid\nsilicon pursued over three decades, with salient experimental, theoretical and\nsimulation results. Following which we present various scenarios put forward to\nrationalize the density and related anomalies often observed in water and other\nnetwork forming liquids. After which we present the more recent investigations\n(both simulation and experimental works) of the phase behavior of Silicon.\nSince a significant part of metastable silicon work is on a classical empirical\npotential an important question to address is the reliability of this potential\nin describing the behavior of silicon. To provide a critical assessment of the\napplicability of classical simulation results to real silicon we present a\ncomparison of the structural, dynamical, and thermodynamic quantities obtained\nfrom the SW potential with those from ab initio simulations and with available\nexperimental data. We also discuss the sensitivity of the thermodynamic\nproperties to model parameters.",
        "positive": "Phase-Field Study of Polycrystalline Growth and Texture Selection During\n  Melt Pool Solidification: Grain growth competition during solidification determines microstructural\nfeatures, such as dendritic arm spacings, segregation pattern, and grain\ntexture, which have a key impact on the final mechanical properties. During\nmetal additive manufacturing (AM), these features are highly sensitive to\nmanufacturing conditions, such as laser power and scanning speed. The melt pool\n(MP) geometry is also expected to have a strong influence on microstructure\nselection. Here, taking advantage of a computationally efficient multi-GPU\nimplementation of a quantitative phase-field model, we use two-dimensional\ncross-section simulations of a shrinking MP during metal AM, at the scale of\nthe full MP, in order to explore the resulting mechanisms of grain growth\ncompetition and texture selection. We explore MPs of different aspect ratios,\ndifferent initial (substrate) grain densities, and repeat each simulation\nseveral times with different random grain distributions and orientations along\nthe fusion line in order to obtain a statistically relevant picture of grain\ntexture selection mechanisms. Our results show a transition from a weak to a\nstrong $\\langle10\\rangle$ texture when the aspect ratio of the melt pool\ndeviates from unity. This is attributed to the shape and directions of thermal\ngradients during solidification, and seems more pronounced in the case of wide\nmelt pools than in the case of a deeper one. The texture transition was not\nfound to notably depend upon the initial grain density along the fusion line\nfrom which the melt pool solidifies epitaxially."
    },
    {
        "anchor": "Universal Power-Law Strengthening in Metals?: The strength of most metals used in daily life scales with either an internal\nor external length scale. Empirically, this is characterized by power-laws\npersisting to six orders of magnitude in both strength and length scale.\nAttempts at understanding this scaling have generally been based on a specific\nmechanism. However the wide applicability of material type and microstructure\nto this phenomenon suggests a single mechanism is unlikely to capture the\nobserved trend. Here we develop a model which gives quantitative insight into\nthe scaling exponent using the known universal properties of a dislocation\nnetwork and the leading order stress dependence of an underlying critical\nstress distribution. This approach justifies a value for the scaling exponent\nfor virtually any experimental data set within the frameworks of both\nHall-Petch strengthening and the \"small is stronger\" paradigm of small scale\nplasticity.",
        "positive": "Strongly Non-Arrhenius Self-Interstitial Diffusion in Vanadium: We study diffusion of self-interstitial atoms (SIAs) in vanadium via\nmolecular dynamics simulations. The <111>-split interstitials are observed to\ndiffuse one-dimensionally at low temperature, but rotate into other <111>\ndirections as the temperature is increased. The SIA diffusion is highly\nnon-Arrhenius. At T<600 K, this behavior arises from temperature-dependent\ncorrelations. At T>600 K, the Arrhenius expression for thermally activated\ndiffusion breaks down when the migration barriers become small compared to the\nthermal energy. This leads to Arrhenius diffusion kinetics at low T and\ndiffusivity proportional to temperature at high T."
    },
    {
        "anchor": "Optical Properties of Isolated and Supported Metal Nanoparticles: A review of the main phenomena related with the linear optical properties of\nisolated and supported metal nanoparticles is presented. The extinction,\nabsorption and scattering efficiencies are calculated using the Mie theory and\nthe Discrete Dipole Approximation. The origin of the optical spectra is\ndiscussed in terms of the size, shape and environment for each nanoparticle.\nThe main optical features of each nanoparticle are identified, showing the\ntremendous potentiality of optical spectroscopy as a tool of characterization.",
        "positive": "On the Solvability of an Euler Graphene Beam Subject to Axial\n  Compressive Load: In this paper we formulate the equilibrium equation of a beam made of\ngraphene material subjected to some boundary conditions and acted upon by axial\ncompression and nonlinear lateral constrains as a fourth-order nonlinear\nboundary value problem. We also formulate the nonlinear eigenvalue for buckling\nanalysis of the beam. We verify the solvability of the buckling problem as an\nasymptotic expansion in a ratio of the elastoplastic parameters, that the\nspectrum is bounded away from zero and contains a discrete infinite sequence of\neigenvalues.We also verify, for certain ranges of the lateral forces, the\nsolvability of the general equations using energy methods and a suitable\niteration scheme."
    },
    {
        "anchor": "Probing the Manipulation of Antiferromagnetic Order in CuMnAs Films\n  Using Neutron Diffraction: We describe measurements of the uniaxial magnetic anisotropy and spin-flop\nrotation of the N\\'eel vector in antiferromagnetic CuMnAs thin films using\nneutron diffraction. The suppression of the magnetic (100) peak under magnetic\nfields is observed for films as thin as 20 nm indicating that they undergo a\nspin-flop transition. Good agreement is found between neutron diffraction and\nelectron transport measurements of the spin-flop rotation in the same layer,\nwith a similar shape and hysteresis of the obtained curves, while the neutron\nmeasurements provide a quantitative determination of the spin flop extent\nthroughout the antiferromagnet layer.",
        "positive": "Efficient calculation of carrier scattering rates from first principles: The electronic transport behaviour of materials determines their suitability\nfor technological applications. We develop an efficient method for calculating\ncarrier scattering rates of solid-state semiconductors and insulators from\nfirst principles inputs. The present method extends existing polar and\nnon-polar electron-phonon coupling, ionized impurity, and piezoelectric\nscattering mechanisms formulated for isotropic band structures to support\nhighly anisotropic materials. We test the formalism by calculating the\nelectronic transport properties of 16 semiconductors and comparing the results\nagainst experimental measurements. The present work is amenable for use in\nhigh-throughput computational workflows and enables accurate screening of\ncarrier mobilities, lifetimes, and thermoelectric power."
    },
    {
        "anchor": "Indirect Spin Exchange Interaction in Substituted Copper Phthalocyanine\n  Crystalline Thin Films: The origins of indirect spin exchange in crystalline thin films of Copper\nOctabutoxy Phthalocyanine (Cu-OBPc) are investigated using Magnetic Circular\nDichroism (MCD) spectroscopy. These studies are made possible by a solution\ndeposition technique which produces highly ordered films with macroscopic grain\nsizes suitable for optical studies. For temperatures lower than 2 K, the\ncontribution of a specific state in the valence band manifold originating from\nthe hybridized lone pair in nitrogen orbitals of the Phthalocyanine ring, bears\nthe Brillouin-like signature of an exchange interaction with the localized\n$\\textit{d}$-shell Cu spins. A comprehensive MCD spectral analysis coupled with\na molecular field model of a $\\sigma\\pi-d$ exchange analogous to\n$\\textit{sp-d}$ interactions in Diluted Magnetic Semiconductors (DMS) renders\nan enhanced Zeeman splitting and a modified $\\textit{g}$-factor of -4 for the\nelectrons that mediate the interaction. These studies define an experimental\ntool for identifying electronic states involved in spin-dependent exchange\ninteractions in organic materials.",
        "positive": "Charting nanocluster structures via convolutional neural networks: A general method to obtain a representation of the structural landscape of\nnanoparticles in terms of a limited number of variables is proposed. The method\nis applied to a large dataset of parallel tempering molecular dynamics\nsimulations of gold clusters of 90 and 147 atoms, silver clusters of 147 atoms,\nand copper clusters of 147 atoms, covering a plethora of structures and\ntemperatures. The method leverages convolutional neural networks to learn the\nradial distribution functions of the nanoclusters and to distill a\nlow-dimensional chart of the structural landscape. This strategy is found to\ngive rise to a physically meaningful and differentiable mapping of the atom\npositions to a low-dimensional manifold, in which the main structural motifs\nare clearly discriminated and meaningfully ordered. Furthermore, unsupervised\nclustering on the low-dimensional data proved effective at further splitting\nthe motifs into structural subfamilies characterized by very fine and\nphysically relevant differences, such as the presence of specific punctual or\nplanar defects or of atoms with particular coordination features. Owing to\nthese peculiarities, the chart also enabled tracking of the complex structural\nevolution in a reactive trajectory. In addition to visualization and analysis\nof complex structural landscapes, the presented approach offers a general,\nlow-dimensional set of differentiable variables which has the potential to be\nused for exploration and enhanced sampling purposes."
    },
    {
        "anchor": "Symmetry and Degeneracy of Phonon Modes for Periodic Structures with\n  Glide Symmetry: A large class of phononic crystals and mechanical metamaterials exhibit glide\nsymmetry that dictates their functionality or exceptional performance. The\nglide symmetry gives rise to a number of intriguing phenomena like\nsticking-bands and degeneracy in the phononic band structures. Fully\nunderstanding of these phenomena demands analysis of the phonon modes' symmetry\nproperty, which is, however, a challenging task since it involves nonsymmorphic\nspace group analysis and special treatment to the Brillouin zone boundary.\nTherefore, this work introduces a systematic group-theoretical procedure\ndetermining the symmetry of phonon modes for periodic structures with glide\nsymmetry. By taking the p4g group as an example, the symmetry of phonon modes\nis discussed by deriving the small representations for high symmetry k-points,\nand different types of degeneracies are elucidated. This work provides insight\ninto the role of glide symmetry on phononic band structures and guides the\nsymmetry analysis to periodic structures of other types.",
        "positive": "Thermopower of correlated semiconductors : application to FeAs2 and\n  FeSb2: We investigate the effect of electronic correlations onto the\nthermoelectricity of semi-conductors and insulators. Appealing to model\nconsiderations, we study various many-body renormalizations that enter the\nthermoelectric response. We find that, contrary to the case of correlated\nmetals, correlation effects do not per se enhance the Seebeck coefficient or\nthe figure of merit, for the former of which we give an upper bound in the\nlimit of vanishing vertex corrections. For two materials of current interest,\nFeAs2 and FeSb2, we compute the electronic structure and thermopower. We find\nFeAs2 to be well described within density functional theory, and the therefrom\ndeduced Seebeck coefficient to be in quantitative agreement with experiment.\nThe capturing of the insulating ground state of FeSb2, however, requires the\ninclusion of many-body effects, in which we succeed by applying the GW\napproximation. Yet, while we get qualitative agreement for the thermopower of\nFeSb2 at intermediate temperatures, the tremendously large Seebeck coefficient\nat low temperatures is found to violate our upper bound, suggesting the\npresence of decisive (e.g. phonon mediated) vertex corrections."
    },
    {
        "anchor": "MAELAS 2.0: A new version of a computer program for the calculation of\n  magneto-elastic properties: MAELAS is a computer program for the calculation of magnetocrystalline\nanisotropy energy, anisotropic magnetostrictive coefficients and magnetoelastic\nconstants in an automated way. The method originally implemented in version 1.0\nof MAELAS was based on the length optimization of the unit cell, proposed by Wu\nand Freeman, to calculate the anisotropic magnetostrictive coefficients. We\npresent here a revised and updated version (v2.0) of MAELAS, where we added a\nnew methodology to compute anisotropic magnetoelastic constants from a linear\nfitting of the energy versus applied strain. We analyze and compare the\naccuracy of both methods showing that the new approach is more reliable and\nrobust than the one implemented in version 1.0, especially for non-cubic\ncrystal symmetries. This analysis also help us to find that the accuracy of the\nmethod implemented in version 1.0 could be improved by using deformation\ngradients derived from the equilibrium magnetoelastic strain tensor, as well as\npotential future alternative methods like the strain optimization method.\nAdditionally, we clarify the role of the demagnetized state in the fractional\nchange in length, and derive the expression for saturation magnetostriction for\npolycrystals with trigonal, tetragonal and orthorhombic crystal symmetry. In\nthis new version, we also fix some issues related to trigonal crystal symmetry\nfound in version 1.0.",
        "positive": "Interplay between Ferroelectricity and Metallicity in BaTiO$_3$: We explore the interplay between ferroelectricity and metallicity, which are\ngenerally considered to be contra-indicated properties, in the prototypical\nferroelectric barium titanate, BaTiO$_3$. Using first-principles density\nfunctional theory, we calculate the effects of electron and hole doping, first\nby introducing a hypothetical background charge, and second through the\nintroduction of explicit impurities (La, Nb and V for electron doping, and K,\nAl and Sc for hole doping). We find that, apart from a surprising increase in\npolarization at small hole concentrations, both charge-carrier types decrease\nthe tendency towards ferroelectricity, with the strength of the polarization\nsuppression, which is different for electrons and holes, determined by the\ndetailed structure of the conduction and valence bands. Doping with impurity\natoms increases the complexity and allows us to identify three factors that\ninfluence the ferroelectricity: structural effects arising largely from the\nsize of the impurity ion, electronic effects from the introduction of charge\ncarriers, and changes in unit-cell volume and shape. A competing balance\nbetween these contributions can result in an increase or decrease in\nferroelectricity with doping."
    },
    {
        "anchor": "Silver environment and covalent network rearrangement in GeS3-Ag glasses: The structure of Ag-doped GeS3 glasses (0, 15, 20, 25 at.% Ag) was\ninvestigated by diffraction techniques and extended x-ray absorption fine\nstructure measurements. Structural models were obtained by fitting the\nexperimental datasets simultaneously by the reverse Monte Carlo simulation\ntechnique. It is observed that Ge has mostly S neighbours in GeS3, but Ge-Ge\nbonds appear already at 15% Ag content. Sulfur has ~2 S/Ge neighbours over the\nwhole concentration range, while the S-Ag coordination number increases with\nincreasing Ag content. Ag-Ag pairs can already be found at 15% Ag. The Ag-S\nmean coordination number changes from 2.17 +/- 0.2 to 2.86 +/- 0.2 between 15%\nand 25% Ag content. Unlike the As-S network in AsS2-25Ag glass, the Ge-S\nnetwork is not fragmented upon Ag-doping of GeS3 glass.",
        "positive": "Anharmonic Phonons and Magnons in BiFeO3: The phonon density of states (DOS) and magnetic excitation spectrum of\npolycrystalline BiFeO$_3$ were measured for temperatures $200 \\leq T \\leq\n750\\,$K, using inelastic neutron scattering (INS). Our results indicate that\nthe magnetic spectrum of BiFeO$_3$ closely resembles that of similar Fe\nperovskites, such as LaFeO$_3$, despite the cycloid modulation in BiFeO$_3$. We\ndo not find any evidence for a spin gap. A strong $T$-dependence of the phonon\nDOS was found, with a marked broadening of the whole spectrum, providing\nevidence of strong anharmonicity. This anharmonicity is corroborated by\nlarge-amplitude motions of Bi and O ions observed with neutron diffraction.\nThese results highlight the importance of spin-phonon coupling in this\nmaterial."
    },
    {
        "anchor": "Current-driven vortex domain wall dynamics by micromagnetic simulations: Current-driven vortex wall dynamics is studied by means of a two-dimensional\nanalytical model and micromagnetic simulation. By constructing a trial function\nfor the vortex wall in the magnetic wire, we analytically solve for domain wall\nvelocity and deformation in the presence of the current-induced spin torque. A\ncritical current for the domain wall transformation from the vortex wall to the\ntransverse wall is calculated. A comparison between the field- and\ncurrent-driven wall dynamics is carried out. Micromagnetic simulations are\nperformed to verify our analytical results.",
        "positive": "Protective Coating Interfaces for perovskite Solar Cell Materials: A\n  first Principles Study: The protection of halide perovskites is important for the performance and\nstability of emergent perovskite-based optoelectronic technologies. In this\nwork, we investigate the potential inorganic protective coating materials ZnO,\nSrZrO3, and ZrO2 for the CsPbI3perovskite. The optimal interface registries are\nidentified with Bayesian optimization. We then use semi-local\ndensity-functional theory (DFT) to determine the atomic structure at the\ninterfaces of each coating material with the clean CsI-terminated surface and\nthree reconstructed surface models with added PbI2and CsI complexes. For the\nfinal structures, we explore the level alignment at the interface with hybrid\nDFT calculations. Our analysis of the level alignment at the coating-substrate\ninterfaces reveals no detrimental mid-gap states, but substrate-dependent\nvalence and conduction band offsets. While ZnO and SrZrO3act as insulators on\nCsPbI3, ZrO2 might be suitable as electron transport layer with the right\ninterface engineering."
    },
    {
        "anchor": "Giant Modulation of Refractive Index from Picoscale Atomic Displacements: Structural disorder has been shown to enhance and modulate magnetic,\nelectrical, dipolar, electrochemical, and mechanical properties of materials.\nHowever, the possibility of obtaining novel optical and optoelectronic\nproperties from structural disorder remains an open question. Here, we show\nunambiguous evidence of disorder in the form of anisotropic, picoscale atomic\ndisplacements modulating the refractive index tensor and resulting in the giant\noptical anisotropy observed in BaTiS$_3$, a quasi-one-dimensional hexagonal\nchalcogenide. Single crystal X-ray diffraction studies reveal the presence of\nantipolar displacements of Ti atoms within adjacent TiS$_6$ chains along the\nc-axis, and three-fold degenerate Ti displacements in the a-b plane.\n$^{47/49}$Ti solid-state NMR provides additional evidence for those Ti\ndisplacements in the form of a three-horned NMR lineshape resulting from a low\nsymmetry local environment around Ti atoms. We used scanning transmission\nelectron microscopy to directly observe the globally disordered Ti a-b plane\ndisplacements and find them to be ordered locally over a few unit cells.\nFirst-principles calculations show that the Ti a-b plane displacements\nselectively reduce the refractive index along the ab-plane, while having\nminimal impact on the refractive index along the chain direction, thus\nresulting in a giant enhancement in the optical anisotropy. By showing a strong\nconnection between structural disorder with picoscale displacements and the\noptical response in BaTiS$_3$, this study opens a pathway for designing optical\nmaterials with high refractive index and functionalities such as large optical\nanisotropy and nonlinearity.",
        "positive": "First-principles investigation of half-metallic ferromagnetism of\n  half-Heusler compounds XYZ: We investigate the electronic structure and magnetism of half-Heusler\ncompounds XYZ (X, Y=V, Cr, Mn, Fe, Co and Ni; Z=Al, Ga, In, Si, Ge, Sn, P, As,\nand Sb) using the ab initio density functional theory calculations. Nine\nhalf-metals with half-Heusler structure have been predicted with the\nhalf-metallic gap of 0.07-0.67 eV. The calculations show that the formation\nenergies for these nine half-Heusler compounds range from -1.32 to -0.12\neV/f.u., and for CoCrSi, CoCrGe, CoFeGe, CoMnSi, CoMnGe, FeMnGe and FeMnAs, the\ntotal energy differences between the half-Heusler structure and the\ncorresponding ground-state structure are small (0.07-0.76 eV/f.u.), thus it is\nexpected that they would be realized in the form of thin films under metastable\nconditions for spintronic applications. The stability of the half-metallicity\nof CoCrGe and FeMnAs to the lattice distortion is also investigated in detail."
    },
    {
        "anchor": "Illuminating the property space in crystal structure prediction using\n  Quality-Diversity algorithms: The identification of materials with exceptional properties is an essential\nobjective to enable technological progress. We propose the application of\n\\textit{Quality-Diversity} algorithms to the field of crystal structure\nprediction. The objective of these algorithms is to identify a diverse set of\nhigh-performing solutions, which has been successful in a range of fields such\nas robotics, architecture and aeronautical engineering. As these methods rely\non a high number of evaluations, we employ machine-learning surrogate models to\ncompute the interatomic potential and material properties that are used to\nguide optimisation. Consequently, we also show the value of using neural\nnetworks to model crystal properties and enable the identification of novel\ncomposition--structure combinations. In this work, we specifically study the\napplication of the MAP-Elites algorithm to predict polymorphs of TiO$_2$. We\nrediscover the known ground state, in addition to a set of other polymorphs\nwith distinct properties. We validate our method for C, SiO$_2$ and SiC\nsystems, where we show that the algorithm can uncover multiple local minima\nwith distinct electronic and mechanical properties.",
        "positive": "Intense terahertz laser fields on a two-dimensional electron gas with\n  Rashba spin-orbit coupling: The spin-dependent density of states and the density of spin polarization of\nan InAs-based two-dimensional electron gas with the Rashba spin-orbit coupling\nunder an intense terahertz laser field are investigated by utilizing the\nFloquet states to solve the time-dependent Schr\\\"odinger equation.\n  It is found that both densities are strongly affected by the terahertz laser\nfield. Especially a terahertz magnetic moment perpendicular to the external\nterahertz laser field in the electron gas is induced. This effect can be used\nto convert terahertz electric signals into terahertz magnetic ones efficiently."
    },
    {
        "anchor": "Theoretical study of doped-Tl$_{2}$Mn$_{2}$O$_{7}$ and\n  Tl$_{2}$Mn$_{2}$O$_{7}$ under pressure: Using first-principles density functional based calculations, we study the\neffect of doping and pressure in manganese based pyrochlore\ncompound,Tl$_{2}$Mn$_{2}$O$_{7}$ that exhibits colossal magneto-resistive\nbehavior. The theoretical study is motivated by the counter-intuitive\nexperimental observation of suppression of ferromagnetic transition temperature\nupon application of pressure and its enhancement upon substitution of Mn by\nmoderate amount of nonmagnetic Sb ion. We also attempt to resolve the issue\nrelated to crystal structure changes that may occur upon application of\npressure.",
        "positive": "UV-isomerisation in nematic elastomers as a route to photo-mechanical\n  transducer: The macroscopic shape of liquid crystalline elastomers strongly depends on\nthe order parameter of the mesogenic groups. This order can be manipulated if\nphotoisomerisable groups, e.g. containing N=N bonds, are introduced into the\nmaterial. We have explored the large photo-mechanical response of such an\nazobenzene-containing nematic elastomer at different temperatures, using force\nand optical birefringence measurements, and focusing on fundamental aspects of\npopulation dynamics and the related speed and repeatability of the response.\nThe characteristic time of ``on'' and ``off'' regimes strongly depends on\ntemperature, but is generally found to be very long. We were able to verify\nthat the macroscopic relaxation of the elastomer is determined by the nematic\norder dynamics and not, for instance, by the polymer network relaxation."
    },
    {
        "anchor": "Improved cutoff functions for short-range potentials and the Wolf\n  summation: A class of radial, polynomial cutoff functions $f_{\\textrm{c}n}(r)$ for\nshort-ranged pair potentials or related expressions is proposed. Their\nderivatives up to order $n$ and $n+1$ vanish at the outer cutoff $r_\\textrm{c}$\nand an inner radius $r_\\textrm{i}$, respectively. Moreover, $f_{\\textrm{c}n}(r\n\\le r_\\textrm{i}) = 1$ and $f_{\\textrm{c}n}(r\\ge r_\\textrm{c})=0$. It is shown\nthat the used order $n$ can qualitatively affect results: stress and bulk\nmoduli of ideal crystals are unavoidably discontinuous with density for $n=0$\nand $n=1$, respectively. Systematic errors on energies and computing times\ndecrease by approximately 25\\% for Lennard-Jones with $n=2$ or $n=3$ compared\nto standard cutting procedures. Another cutoff function turns out beneficial to\ncompute Coulomb interactions using the Wolf summation, which is shown to not\nproperly converge when local charge neutrality is obeyed only in a stochastic\nsense. However, for all investigated homogeneous systems with thermal noise\n(ionic crystals and liquids), the modified Wolf summation, despite being\ninfinitely differentiable at $r_\\textrm{c}$, converges similarly quickly as the\noriginal summation. Finally, it is discussed how to reduce the computational\ncost of numerically exact Monte Carlo simulations using the Wolf summation even\nwhen it does not properly converge.",
        "positive": "Elementary transitions and magnetic correlations in two-dimensional\n  disordered nanoparticle ensembles: The magnetic relaxation processes in disordered two-dimensional ensembles of\ndipole-coupled magnetic nanoparticles are theoretically investigated by\nperforming numerical simulations. The energy landscape of the system is\nexplored by determining saddle points, adjacent local minima, energy barriers,\nand the associated minimum energy paths (MEPs) as functions of the structural\ndisorder and particle density. The changes in the magnetic order of the\nnanostructure along the MEPs connecting adjacent minima are analyzed from a\nlocal perspective. In particular, we determine the extension of the correlated\nregion where the directions of the particle magnetic moments vary\nsignificantly. It is shown that with increasing degree of disorder the magnetic\ncorrelation range decreases, i.e., the elementary relaxation processes become\nmore localized. The distribution of the energy barriers, and their relation to\nthe changes in the magnetic configurations are quantified. Finally, some\nimplications for the long-time magnetic relaxation dynamics of nanostructures\nare discussed."
    },
    {
        "anchor": "Electronic and Thermal Properties of $\\text{GeTe/Sb}_{2}\\text{Te}_{3}$\n  Superlattices by ab-initio Approach: Impact of Van der Waals Gaps on Vertical\n  Lattice Thermal Conductivity: In the last decade, several works have focused on exploring the material and\nelectrical properties of $\\text{GeTe/Sb}_{2}\\text{Te}_{3}$ superlattices (SLs)\nin particular because of some first device implementations demonstrating\ninteresting performances such as fast switching speed, low energy consumption,\nand non-volatility. However, the switching mechanism in such SL-based devices\nremains under debate. In this work, we investigate the prototype\n$\\text{GeTe/Sb}_{2}\\text{Te}_{3}$ SLs, to analyze fundamentally their\nelectronic and thermal properties by ab initio methods. We find that the\nresistive contrast is small among the different phases of\n$\\text{GeTe/Sb}_{2}\\text{Te}_{3}$ because of a small electronic gap (about 0.1\neV) and a consequent semi-metallic-like behavior. At the same time the\nout-of-plane lattice thermal conductivity is rather small, while varying up to\nfour times among the different phases, from 0.11 to 0.45 W/m$^{-1}$K$^{-1}$,\nintimately related to the number of Van der Waals (VdW) gaps in a unit block.\nSuch findings confirm the importance of the thermal improvement achievable in\n$\\text{GeTe/Sb}_{2}\\text{Te}_{3}$ super-lattices devices, highlighting the\nimpact of the material stacking and the role of VdW gaps on the thermal\nengineering of the Phase-Change Memory cell.",
        "positive": "The Effect of dopants on magnetic properties of the ordered\n  Fe_{65-x}Al_{35-y}M_{x,y} (M=Ga,B,V; x,y=5,10) alloys: The results of X-ray diffraction, complex in-field (up to 9 T) and\ntemperature (5-300 K) Moessbauer and magnetometric studies of the ordered\nFe_{65}Al_{35-x}M_x (M=Ga, B; x=0,5,10) and Fe_{65-x}V_xAl_{35} (x=5,10) alloys\nare presented. Analysis of the magnetometry studies shows that the systems\nFe_{65}Al_{35} and Fe_{65}Al_{35-x}Ga_x (x=5, 10) are characterized by two\ndifferent magnetic states with essentially distinguishing hysteresis loops and\nAC susceptibility values. The temperature and external magnetic field values\ninducing the transition from one magnetic state to another are higher in the\nGa-doped alloys than in the reference Fe_{65}Al_{35} alloy. The boron addition\ntransforms the magnetic state of the initial alloy Fe_{65}Al_{35} into a\nferromagnetic one exhibiting high magnetic characteristics. Substitution of V\nfor Fe in the ternary alloys Fe_{65-x}V_xAl_{35} results in reduction of\nmagnetic characteristics and collapsing of 57Fe hyperfine magnetic filed."
    },
    {
        "anchor": "Atomistic origin of exchange anisotropy in $\u03b3$-IrMn$_3$-CoFe\n  bilayers: The exchange interaction determines the ferromagnetic (FM) or\nantiferromagnetic (AFM) ordering of atomic spins. When ferromagnets and\nantiferromagnets are coupled together, they often exhibit the exchange bias\neffect, a unidirectional interface exchange field causing a shift of the\nmagnetic hysteresis loop. The effective magnitude of this interface exchange\nfield is at most a few percent of the bulk exchange, arising from pinned\ninterfacial spins in the antiferromagnet. The pinned spins are known to\ncomprise a small fraction of the total number of interface spins, yet their\nexact nature and physical origin has so far been elusive. Here we show that in\nthe technologically important $\\gamma - IrMn_3/CoFe$ structure the pinned\ninterface spins are in fact delocalised over the whole interface layer. The\npinned spins arise from the small imbalance of the number of spins in each\nmagnetic sublattice in the antiferromagnet due to the natural atomic disorder.\nThese pinned spins are strongly coupled to the bulk antiferromagnet explaining\ntheir remarkable stability. Moreover, we find that the ferromagnet strongly\ndistorts the interface spin structure of the antiferromagnet, causing a large\nreversible interface magnetisation that does not contribute to exchange bias.\nThe unexpected delocalised nature of the pinned interface spins explains both\ntheir small number and their stability, uncovering the mysterious microscopic\norigin of the exchange bias effect.",
        "positive": "Low-symmetry two-dimensional BNP$_2$ and C$_2$SiS structures with high\n  and anisotropic carrier mobilities: We study the stability and electronic structure of previously unexplored\ntwo-dimensional (2D) ternary compounds BNP$_2$ and C$_2$SiS. Using $ab$\n$initio$ density functional theory, we have identified four stable allotropes\nof each ternary compound and confirmed their stability by calculated phonon\nspectra and molecular dynamics simulations. Whereas all BNP$_2$ allotropes are\nsemiconducting, we find C$_2$SiS, depending on the allotrope, to be\nsemiconducting or semimetallic. The fundamental band gaps of the semiconducting\nallotropes we study range from $1.4$ eV to $2.2$ eV at the HSE06 level $0.5$ eV\nto $1.4$ eV at the PBE level and display carrier mobilities as high as\n$1.5{\\times}10^5$ cm$^2$V$^{-1}$s$^{-1}$. Such high mobilities are quite\nuncommon in semiconductors with so wide band gaps. Structural ridges in the\ngeometry of all allotropes cause a high anisotropy in their mechanical and\ntransport properties, promising a wide range of applications in electronics and\noptoelectronics."
    },
    {
        "anchor": "Photoluminescence of freestanding single- and few-layer MoS2: We present a photoluminescence study of freestanding and Si/SiO2 supported\nsingle- and few-layer MoS2. The single-layer exciton peak (A) is only observed\nin freestanding MoS2. The photoluminescence of supported single-layer MoS2 is\ninstead originating from the A- (trion) peak as the MoS2 is n-type doped from\nthe substrate. In bilayer MoS2, the van der Waals interaction with the\nsubstrate is decreasing the indirect band gap energy by up to ~ 80 meV.\nFurthermore, the photoluminescence spectra of suspended MoS2 can be influenced\nby interference effects.",
        "positive": "Dimensional crossover of the exchange-correlation energy at the\n  semilocal level: Commonly used semilocal density functional approximations for the\nexchange-correlation energy fail badly when the true two dimensional limit is\napproached. We show, using a quasi-two-dimensional uniform electron gas in the\ninfinite barrier model, that the semilocal level can correctly recover the\nexchange-correlation energy of the two-dimensional uniform electron gas. We\nderive new exact constraints at the semilocal level for the dimensional\ncrossover of the exchange-correlation energy and we propose a method to\nincorporate them in any exchange-correlation density functional approximation."
    },
    {
        "anchor": "Monitoring Galvanic Replacement Through Three-Dimensional Morphological\n  and Chemical Mapping: Galvanic replacement reactions on metal nanoparticles are often used for the\npreparation of hollow nanostructures with tunable porosity and chemical\ncomposition, leading to tailored optical and catalytic properties. However, the\nprecise interplay between the three-dimensional (3D) morphology and chemical\ncomposition of nanostructures during Galvanic replacement is not always well\nunderstood as the 3D chemical imaging of nanoscale materials is still\nchallenging. It is especially far from straightforward to obtain detailed\ninformation from the inside of hollow nanostructures using electron microscopy\ntechniques such as SEM or TEM. We demonstrate here that a combination of\nstate-of-the-art EDX mapping with electron tomography results in the\nunambiguous determination of both morphology transformation and elemental\ncomposition of nanostructures in 3D, during Galvanic replacement of Ag\nnanocubes. This work provides direct and unambiguous experimental evidence\nleading to new insights in the understanding of the galvanic replacement\nreaction. In addition, the powerful approach presented here can be applied to a\nwide range of nanoscale transformation processes, which will undoubtedly guide\nthe development of novel nanostructures.",
        "positive": "Reversible spin-optical interface in luminescent organic radicals: Molecules present a versatile platform for quantum information science, and\nare candidates for sensing and computation applications. Robust spin-optical\ninterfaces are key to harnessing the quantum resources of materials. To date,\ncarbon-based candidates have been non-luminescent, which prevents optical\nread-out. Here we report the first organic molecules displaying both efficient\nluminescence and near-unity generation yield of high-spin multiplicity excited\nstates. This is achieved by designing an energy resonance between emissive\ndoublet and triplet levels, here on covalently coupled\ntris(2,4,6-trichlorophenyl) methyl-carbazole radicals (TTM-1Cz) and anthracene.\nWe observe the doublet photoexcitation delocalise onto the linked acene within\na few picoseconds and subsequently evolve to a pure high spin state (quartet\nfor monoradicals, quintet for biradical) of mixed radical-triplet character\nnear 1.8 eV. These high-spin states are coherently addressable with microwaves\neven at 295 K, with optical read-out enabled by intersystem crossing to\nemissive states. Furthermore, for the biradical, on return to the ground state\nthe previously uncorrelated radical spins either side of the anthracene show\nstrong spin correlation. Our approach simultaneously supports a high efficiency\nof initialisation, spin manipulations and light-based read-out at room\ntemperature. The integration of luminescence and high-spin states creates an\norganic materials platform for emerging quantum technologies."
    },
    {
        "anchor": "A detailed analysis of impact collision ion scattering spectroscopy of\n  bismuth selenide: Impact collision ion scattering spectroscopy (ICISS), which is a variation of\nlow energy ion scattering (LEIS) that employs large scattering angles, is\nperformed on Bi2Se3 surfaces prepared by ion bombardment and annealing (IBA).\nICISS angular scans are collected experimentally and simulated numerically\nalong the [120] and [-1 -2 0] azimuths, and the match of the positions of the\nflux peaks shows that the top three atomic layers are bulk-terminated. A newly\nobserved feature is identified as a minimum in the multiple scattering\nbackground when the ion beam incidence is along a low index direction.\nCalculated scans as a function of scattering angle are employed to identify the\nbehavior of flux peaks to show whether they originate from shadowing, blocking\nor both. This new method for analysis of large-angle LEIS data is shown to be\nuseful for accurately investigating complex surface structures.",
        "positive": "First-Principles Calculations of Exciton Radiative Lifetimes in\n  Monolayer Graphitic Carbon Nitride Nanosheets: Implications for\n  Photocatalysis: In this work, we report on the exciton radiative lifetimes of graphitic\ncarbon nitride monolayers in the triazine- (gC$_3$N$_4$-t) and heptazine-based\n(gC$_3$N$_4$-h) forms, as obtained by means of ground- plus excited-state ab\ninitio calculations. By analysing the exciton fine structure, we highlight the\npresence of dark states and show that the photo-generated electron-hole pairs\nin gC$_3$N$_4$-h are remarkably long-lived, with an effective radiative\nlifetime of 260 ns. This fosters the employment of gC$_3$N$_4$-h in\nphotocatalysis and makes it attractive for the emerging field of exciton\ndevices. Although very long intrinsic radiative lifetimes are an important\nprerequisite for several applications, pristine carbon nitride nanosheets show\nvery low quantum photo-conversion efficiency, mainly due to the lack of an\nefficient e-h separation mechanism. We then focus on a vertical heterostructure\nmade of gC$_3$N$_4$-t and gC$_3$N$_4$-h layers which shows a type-II band\nalignment and looks promising for achieving net charge separation."
    },
    {
        "anchor": "A Rigorous Extension of the Kohn-Sham Equation for Strongly Correlated\n  Electron Systems: By introducing a set of auxiliary equations representing a many-body system,\nwe have derived an extension of the Kohn-Sham scheme for the density functional\ntheory. These equations consist of a Kohn-Sham-type equation determining\nsingle-particle orbitals and an eigen-value equation for an effective many-body\nproblem. A variational method similar to the Kohn-Sham technique was utilized\nto derive effective interactions as well as effective potentials without\nartificial substitution of a Hubbard-type interaction and a mean-field\ncorrection in the energy functional. The second equation is described by an\neffective many-body Hamiltonian with both 2-body interactions and mean-field\nterms. Rigorous formulation of the extended Kohn-Sham equation is also given in\naccordance with the Hadjisavvas-Theophilou formulation. Our formulation can be\ninterpreted as a way to define models of the strongly correlated electron\nsystems, e.g. the Hubbard model",
        "positive": "Relative stability of a ferroelectric state in (Na0.5Bi0.5)TiO3-based\n  compounds under substitutions: Role of a tolerance factor in expansion of the\n  temperature interval of stable ferroelectric state: The influence of the B-site ion substitutions in\n(1-x)(Bi1/2Na1/2)TiO3-xBaTiO3 system of solid solutions on the relative\nstability of the ferroelectric and antiferroelectric phases has been studied.\nThe ions of zirconium, tin, along with (In0.5Nb0.5), (Fe0.5Nb0.5), (Al0.5V0.5)\nion complexes have been used as substituting elements. An increase in the\nconcentration of the substituting ion results in a near linear variation in the\nsize of the crystal lattice cell. Along with the cell size variation a change\nin the relative stability of the ferroelectric and antiferroelectric phases\ntakes place according to the changes of the tolerance factor of the solid\nsolution. An increase in the tolerance factor leads to the increase in the\ntemperature of the ferroelectric-antiferroelectric phase transition, and vice\nversa. All obtained results demonstrate the predominant influence of the ion\nsize factor on the relative stability of the ferroelectric and\nantiferroelectric states in the (Na0.5Bi0.5)TiO3-based solid solutions and\nindicate the way for raising the temperature of the\nferroelectric-antiferroelectric phase transition."
    },
    {
        "anchor": "Analysis of the $E_{1}$ and $E_{1}$ +$\u0394_{1}$ optical transitions\n  in (Ga,Mn)As epitaxial layers: The diluted (Ga,Mn)As became a model ferromagnetic semiconductor, however\nthere is still a disagreement on the source of its magnetism. The divergences\narise from the results indicating that the holes mediated ferromagnetism reside\nin the valence band or the impurity band. Full understanding of character of\nthe Mn states in GaAs can bring the increase of (Ga,Mn)As Curie temperature. In\nthis paper we verify the ellipsometric results and compare with more precise\nphotoreflectance method which gives a new insight into the interactions of Mn\nimpurity states with GaAs valence band. Indeed, $E_{1}$ and\n$E_{1}$+${\\Delta}_{1}$ inter-band transition energies for highly doped and\nannealed (Ga,Mn)As epitaxial layers have not confirmed the interaction between\ndetached Mn impurity band and the valence band. Thus, the description with\nmerged Mn states and GaAs valence band is in agreement with our results. Our\nfindings are supported by the high resolution transmission microscopy and\nmagnetization measurements.",
        "positive": "Water on Silicene: Hydrogen Bond Autocatalysis Induced\n  Physisorption-Chemisorption-Dissociation Transition: A single water molecule has nothing special. However, macroscopic water\ndisplays many anomalous properties at the interface, such as a high surface\ntension, hydrophobicity and hydrophillicity. Although the underlying mechanism\nis still elusive, hydrogen bond is expected to have played an important role.\nAn interesting question is if the few-water molecule clusters will be\nqualitatively different from a single molecule. Using adsorption behavior as an\nexample, by carefully choosing two-dimensional silicene as the substrate\nmaterial, we demonstrate that water monomer, dimer and trimer show contrasting\nproperties. The additional water molecules in dimer and trimer induce a\ntransition from physisorption to chemisorption then to dissociation on\nsilicene. Such a hydrogen bond autocatalytic effect is expected to have a broad\napplication potential in silicene-based water molecule sensor and metal-free\ncatalyst for water dissociation."
    },
    {
        "anchor": "Thermodynamic dislocation theory of adiabatic shear banding in steel: The statistical-thermodynamic dislocation theory developed in our earlier\nstudies is used here in an analysis of the experimental observations of\nadiabatic shear banding in steel by Marchand and Duffy (1988). Employing a\nsmall set of physics-based parameters, which we expect to be approximately\nindependent of strain rate and temperature, we are able to explain experimental\nstress-strain curves at six different temperatures and four different strain\nrates. We make a simple model of a weak notch-like disturbance that, when\ndriven hard enough, triggers shear banding instabilities that are\nquantitatively comparable with those seen in the experiments.",
        "positive": "Lattice matched Volmer-Weber growth of Fe$_3$Si on GaAs(001) -- the\n  influence of the growth rate: We investigate the formation of lattice matched single-crystalline\nFe$_3$Si/GaAs(001) ferromagnet/semiconductor hybrid structures by Volmer-Weber\nisland growth, starting from the epitaxial growth of isolated Fe$_3$Si islands\nup to the formation of continuous films as a result of island coalescence. We\nfind coherent defect-free layers exhibiting compositional disorder near the\nFe$_3$Si/GaAs-interface for higher growth rates, whereas they are fully ordered\nfor lower growth rates."
    },
    {
        "anchor": "Theoretical description of X-ray absorption spectroscopy of the\n  graphene-metal interfaces: The present manuscript considers the application of the method of the\nnear-edge X-ray absorption spectroscopy (NEXAFS) for the investigation of the\ngraphene-based systems (from free-standing graphene to the\nmetal-intercalation-like systems). The NEXAFS spectra for the selected systems\nare calculated in the framework of the approach, which includes the effects of\nthe dynamic core-hole screening. The presented spectral changes from system to\nsystem are analysed with the help of the corresponding band-structure\ncalculations. The obtained results are compared with available experimental\ndata demonstrating the excellent agreement between theory and experiment. The\ndirect correlation between the strength of the graphene interaction with the\nmetallic substrate and the spectral distributions (shape and intensities of\n\\pi* and \\sigma* features in the C K NEXAFS spectra) is found that can be taken\nas a fingerprint for the description of interaction at the graphene/metal\ninterface.",
        "positive": "High-throughput design of all-d-metal Heusler alloys for magnetocaloric\n  applications: Due to their versatile composition and customizable properties, A$_2$BC\nHeusler alloys have found applications in magnetic refrigeration, magnetic\nshape memory effects, permanent magnets, and spintronic devices. The discovery\nof all-$d$-metal Heusler alloys with improved mechanical properties compared to\nthose containing main group elements, presents an opportunity to engineer\nHeuslers alloys for energy-related applications. Using high-throughput density\nfunctional theory calculations, we screened magnetic all-$d$-metal Heusler\ncompounds and identified 686 (meta)stable compounds. Our detailed analysis\nrevealed that the inverse Heusler structure is preferred when the\nelectronegativity difference between the A and B/C atoms is small, contrary to\nconventional Heusler alloys. Additionally, our calculations of Pugh ratios and\nCauchy pressures demonstrated that ductile and metallic bonding are widespread\nin all-$d$-metal Heuslers, supporting their enhanced mechanical behaviour. We\nidentified 49 compounds with a double-well energy surface based on Bain path\ncalculations and magnetic ground states, indicating their potential as\ncandidates for magnetocaloric and shape memory applications. Furthermore, by\ncalculating the free energies, we propose that 11 compounds exhibit structural\nphase transitions, and propose isostructural substitution to enhance the\nmagnetocaloric effect."
    },
    {
        "anchor": "Pressure and temperature driven phase transitions in HgTe quantum wells: We present theoretical investigations of pressure and temperature driven\nphase transitions in HgTe quantum wells grown on CdTe buffer. Using the 8-band\n\\textbf{k$\\cdot$p} Hamiltonian we calculate evolution of energy band structure\nat different quantum well width with hydrostatic pressure up to 20 kBar and\ntemperature ranging up 300 K. In particular, we show that in addition to\ntemperature, tuning of hydrostatic pressure allows to drive transitions between\nsemimetal, band insulator and topological insulator phases. Our realistic band\nstructure calculations reveal that the band inversion under hydrostatic\npressure and temperature may be accompanied by non-local overlapping between\nconduction and valence bands. The pressure and temperature phase diagrams are\npresented.",
        "positive": "First-principles Studies on Structural, Electronic, Optical and\n  Mechanical Properties of Inorganic CS2NaTlX6 (X = F, Cl, Br) Double Halide\n  Perovskites: The structural, electrical, optical, and mechanical characteristics of the\nlead-free halide double perovskites Cs2NaTlX6 X = F, Cl, Br are calculated by\nutilizing PBE functional within generalized gradient approximation GGA under\nthe context of density functional theory DFT.The structural properties such as\nlattice parameter, cell volume, total energy, bulk modulus, pressure\nderivative, and tolerance factor are computed at equilibrium.The electronic\ndensity of states reveals the semiconducting nature of the compound and the\nband structure exhibits the nature of the band gap to be direct.HSE06\nfunctional is introduced to correct the underestimated band gap as obtained in\nthe GGA-PBE functional.The real and imaginary components of the dielectric\nfunction, absorption coefficient, energy loss function, reflectivity,\nrefractive index, and extinction coefficient are analyzed and explained by\nelectronic structures."
    },
    {
        "anchor": "Thermoelectric prospects of nanomaterials with spin-orbit surface bands: Nanostructured composites and nanowire arrays of traditional thermoelectrics\nlike Bi, Bi(1-x)Sb(x) and Bi(2)Te(3) have metallic Rashba surface spin-orbit\nbands featuring high mobilities rivaling that of the bulk for which topological\ninsulator behavior has been proposed. Nearly pure surface electronic transport\nhas been observed at low temperatures in Bi nanowires with diameter around the\ncritical diameter, 50 nm, for the semimetal-to semiconductor transition. The\nsurface contributes strongly to the thermopower, actually dominating for\ntemperatures T < 100 K in these nanowires. The surface thermopower was found to\nbe -1 T microvolt/(K^2), a value that is consistent with theory. We show that\nsurface electronic transport together with boundary phonon scattering leads to\nenhanced thermoelectric performance at low temperatures of Bi nanowire arrays.\nWe compare with bulk n-BiSb alloys, optimized CsBi(4)Te(6) and optimized\nBi(2)Te(3). Surface dominated electronic transport can be expected in\nnanomaterials of the other traditional thermoelectrics.",
        "positive": "Maximum Supercooling Studies in Ti39.5Zr39.5Ni21 and Zr80Pt20 -\n  Connecting Liquid Structure and the Nucleation Barrier: Almost three quarters of a century ago, Charles Frank proposed that the deep\nsupercooling observed in metallic liquids is due to icosahedral short-range\norder (ISRO), which is incompatible with the long-range order of crystal\nphases. Some evidence in support of this hypothesis has been published\npreviously. However, those studies were based on a small population of maximum\nsupercooling measurements before the onset of crystallization. Here, the\nresults of a systematic statistical study of several hundred maximum\nsupercooling measurements on Ti39.5Zr39.5Ni21 and Zr80Pt20 liquids are\npresented. Previous X-Ray and neutron scattering studies have shown that the\nstructures of these liquid alloys contain significant amounts of ISRO. The\nresults presented here show a small work of critical cluster formation (W* = 31\n- 40 kBT) from the analysis of the supercooling data for the Ti39.5Zr39.5Ni21\nliquid, which crystallizes to a metastable icosahedral quasicrystal. A much\nlarger value (W* = 60 - 99 kBT) was obtained for the Zr80Pt20 liquid, which\ndoes not crystallize to an icosahedral quasicrystal. Taken together, these\nresults significantly strengthen the validity of Frank's hypothesis."
    },
    {
        "anchor": "The kagom\u00e9 metals RbTi$_3$Bi$_5$ and CsTi$_3$Bi$_5$: The kagom\\'e metals RbTi$_3$Bi$_5$ and CsTi$_3$Bi$_5$ were synthesized both\nas polycrystalline powders by heating the elements an argon atmosphere and as\nsingle crystals grown using a self-flux method. The compounds crystallize in\nthe hexagonal crystal system isotypically to KV$_3$Sb$_5$ (P6/mmm, Z = 1,\nCsTi3Bi5: a = 5.7873(1) {\\AA}, c = 9.2062(1) {\\AA}; RbTi3Bi5: a = 5.773(1)\n{\\AA}, c = 9.065(1) {\\AA}). Titanium atoms form a kagom\\'e net with bismuth\natoms in the hexagons as well as above and below the triangles. The alkali\nmetal atoms are coordinated by 12 bismuth atoms and form AlB$_2$-like slabs\nbetween the kagom\\'e layers. Magnetic susceptibility measurements with\nCsTi$_3$Bi$_5$ and RbTi$_3$Bi$_5$ single crystals reveal Pauli-paramagnetism\nand traces of superconductivity caused by CsBi$_2$/RbBi$_2$ impurities.\nMagnetotransport measurements reveal conventional Fermi liquid behavior and\nquantum oscillations indicative of a single dominant orbit at low temperature.\nDFT calculations show the characteristic metallic kagom\\'e band structure\nsimilar to that of CsV$_3$Sb$_5$ with reduced band filling. A symmetry analysis\nof the band structure does not reveal an obvious and unique signature of a\nnontrivial topology.",
        "positive": "Effect of Buffer Termination on Intermixing and Conductivity in\n  LaTiO$_3$/SrTiO$_3$ Heterostructures Integrated on Si(100): The control of chemical exchange across heterointerfaces formed between\nultra-thin functional transition-metal oxide layers provides an effective route\nto manipulate the electronic properties of these systems. We show that cationic\nexchange across the interface between the Mott insulator, LaTiO$_3$(LTO) grown\nepitaxially on SrTiO$_3$(STO)-buffered Silicon by molecular beam epitaxy\ndepends strongly on the surface termination of the strained STO buffer. Using a\ncombination of temperature-dependent transport and synchrotron X-ray crystal\ntruncation rods and reciprocal space mapping, an enhanced conductivity in\nSTO/LTO/SrO- terminated STO buffers compared to heterostructures with\nTiO$_2$-terminated STO buffers is correlated with La/Sr exchange and the\nformation of metallic La$_{1-x}$Sr$_x$TiO$_3$. La/Sr exchange effectively\nreduces the strain energy of the system due to the large lattice mismatch\nbetween the nominal oxide layers and the Si substrate."
    },
    {
        "anchor": "Nearly Lattice Matched GaAs/Pb(1-x)Sn(x)Te Core-Shell Nanowires: We investigate the full and half-shells of Pb(1-x)Sn(x)Te topological\ncrystalline insulator deposited by molecular beam epitaxy on the sidewalls of\nwurtzite GaAs nanowires (NWs). Due to the distinct orientation of the IV-VI\nshell with respect to the III-V core the lattice mismatch along the nanowire\naxis is less than 4%. The Pb(1-x)Sn(x)Te solid solution is chosen due to the\ntopological crystalline insulator properties for some critical concentrations\nof Sn (x >= 0.4). The IV-VI shells are grown with different compositions\nspanning from binary SnTe, through Pb(1-x)Sn(x)Te with decreasing x value down\nto binary PbTe (x = 0). The samples are analyzed by scanning transmission\nelectron microscopy, which reveals the presence of (110) or (100) oriented\nbinary PbTe and (100)Pb(1-x)Sn(x)Te on the sidewalls of wurtzite GaAs NWs.",
        "positive": "Intrinsic shear transformations in metallic glasses: Plastic flow in amorphous solids is known to be carried by localized shear\ntransformations (STs) which have been proposed to preferentially initiate from\nsome defect units in the structure, akin to dislocations and point defects in\ncrystalline solids. Despite the central role of STs in the mechanical\ndeformation of metallic glasses (MGs), our knowledge of their characteristics\nhas so far been limited to hypothetical models, based on computer simulations\nusing unreleastically high cooling rates. Using combined molecular dynamics\n(MD) and Monte Carlo (MC) simulations, here we have succeeded in solidifying a\nmetallic liquid at an effective cooling rate as slow as 500 K/s to approach\nthat typical in experiments for producing bulk MGs. Exploiting this realistic\nMG model, we find that STs do not arise from signature structural defects that\ncan be recognized a priori. Upon yielding, only about 2% of the total atoms\nparticipate in STs, each event involving as few as ~10 atoms. These findings\nrectify the unrealistically high content of liquid-like regions retained in\nMD-produced glass structures, which has rendered the MG model artificially\nductile and under-predicted the sample-wide shear modulus by at least ~20%\n(with respect to that of experimental BMGs). Our finding sheds light on the\nscope of intrinsic structural inhomogeneity as well as the indeterministic\naspect of the ST emergence under mechanical loading."
    },
    {
        "anchor": "Data-driven prediction of room temperature density for multicomponent\n  silicate-based glasses: Density is one of the most commonly measured or estimated materials\nproperties, especially for glasses and melts that are of significant interest\nto many fields, including metallurgy, geology, materials science and\nsustainable cements. Here, two types of machine learning (ML) models (i.e.,\nrandom forest (RF) and artificial neural network (ANN)) have been developed to\npredict the room-temperature density of glasses in the compositional space of\nCaO-MgO-Al2O3-SiO2-TiO2-FeO-Fe2O3-Na2O-K2O-MnO (CMASTFNKM), based on ~2100 data\npoints mined from ~140 literature studies. The results show that the RF and ANN\nmodels give accurate predictions of glass density with R2 values, RMSE, and\nMAPE of ~0.96-0.98, ~0.02-0.03 g/cm3 and ~0.59-0.79%, respectively, for the 15%\ntesting set, which are more accurate compared with empirical density models\nbased on ionic packing ratio (with R2 values, RMSE, and MAPE of ~0.28-0.91,\n~0.05-0.15 g/cm3, and ~1.40-4.61%, respectively). Furthermore, glass density is\nshown to be a reliable reactivity indicator for a range of CaO-Al2O3-SiO2 (CAS)\nand volcanic glasses due to its strong correlation (R2 values above ~0.90) with\nthe average metal-oxygen dissociation energy (a structural descriptor) of these\nglasses. Analysis of the predicted density-composition relationships from these\nmodels (for selected compositional subspaces) suggests that the ANN model\nexhibits a certain level of transferability (i.e., ability to extrapolate to\ncompositional space not (or less) covered in the database) and captures known\nfeatures including the mixed alkaline earth effects for\n(CaO-MgO)0.5-(Al2O3-SiO2)0.5 glasses.",
        "positive": "Direct writing of room temperature polariton condensate lattice by\n  top-down approach: Realizing lattices of exciton polariton condensates has been of much interest\nowing to the potential of such systems to realize analog Hamiltonian simulators\nand physical computing architectures. Prior work on polariton condensate\nlattices has primarily been on GaAs-based systems, with the recent advent of\norganic molecules and perovskite systems allowing room-temperature operation.\nHowever, in most of these room temperature systems, the lattices are defined\nusing a bottom-up approach by patterning the bottom mirrors, significantly\nlimiting the types of lattices and refractive index contrast that can be\nrealized. Here, we report a direct write approach that uses a Focused Ion Beam\n(FIB) to etch 2D lattice into a planar microcavity. Such etching of the cavity\nallows for realizing high refractive index contrast lattices. We realize the\npolariton condensate lattice using the highly photostable host-guest Frenkel\nexcitons of an organic dye small molecular ionic lattice (SMILES).1,2 The\nlattice structures are defined on a planar microcavity embedded with SMILES\nusing FIB, allowing the realization of lattices with different geometries,\nincluding defect sites on demand. The band structure of the lattice and the\nemergence of condensation are imaged using momentum-resolved spectroscopy. The\npresent approach allows us to study periodic, quasi-periodic, and disordered\npolariton condensate lattices at room temperature using a top-down approach\nwithout compromising on the quantum yield of the organic excitonic material\nembedded in the cavity."
    },
    {
        "anchor": "Quantum theory of the Intrinsic Orbital Magnetoelectric Effect in\n  itinerant electron systems at finite temperatures: Magnetization can be induced by an electric field in systems without\ninversion symmetry $\\mathcal{P}$ and time-reversal symmetry $\\mathcal{T}$. This\nphenomenon is called the magnetoelectric (ME) effect. The spin ME effect has\nbeen actively studied in multiferroics. The orbital ME effect also exists and\nhas been mainly discussed in topological insulators at zero temperature. In\nthis paper, we study the intrinsic orbital ME response in metals at finite\ntemperature using the Kubo formula. The intrinsic response originates from the\nFermi sea and does not depend on the dissipation. Especially in systems with\n$\\mathcal{PT}$-symmetry, the extrinsic orbital ME effect becomes zero, and the\nintrinsic ME effect is dominant. We apply the response tensor obtained in this\nwork to a $\\mathcal{PT}$-symmetric model Hamiltonian with antiferromagnetic\nloop current order demonstrating that the intrinsic ME effect is enhanced\naround the Dirac points.",
        "positive": "Phononic filter effect of rattling phonons in the thermoelectric\n  clathrate Ba$_8$Ge$_{40+x}$Ni$_{6-x}$: One of the key requirements for good thermoelectric materials is a low\nlattice thermal conductivity. Here we present a combined neutron scattering and\ntheoretical investigation of the lattice dynamics in the type I clathrate\nsystem Ba-Ge-Ni, which fulfills this requirement. We observe a strong\nhybridization between phonons of the Ba guest atoms and acoustic phonons of the\nGe-Ni host structure over a wide region of the Brillouin zone which is in\ncontrast with the frequently adopted picture of isolated Ba atoms in Ge-Ni host\ncages. It occurs without a strong decrease of the acoustic phonon lifetime\nwhich contradicts the usual assumption of strong anharmonic phonon--phonon\nscattering processes. Within the framework of ab-intio density functional\ntheory calculations we interpret these hybridizations as a series of an\nti-crossings which act as a low pass filter, preventing the propagation of\nacoustic phonons. To highlight the effect of such a phononic low pass filter on\nthe thermal transport, we compute the contribution of acoustic phonons to the\nthermal conductivity of Ba$_8$Ge$_{40}$Ni$_{6}$ and compare it to those of pure\nGe and a Ge$_{46}$ empty-cage model system."
    },
    {
        "anchor": "Local probing of ionic diffusion by electrochemical strain microscopy:\n  spatial resolution and signal formation mechanisms: Electrochemical insertion-deintercalation reactions are typically associated\nwith significant change of molar volume of the host compound. This strong\ncoupling between ionic currents and strains underpins image formation\nmechanisms in electrochemical strain microscopy (ESM), and allows exploring the\ntip-induced electrochemical processes locally. Here we analyze the signal\nformation mechanism in ESM, and develop the analytical description of operation\nin frequency and time domains. The ESM spectroscopic modes are compared to\nclassical electrochemical methods including potentiostatic and galvanostatic\nintermittent titration (PITT and GITT), and electrochemical impedance\nspectroscopy (EIS). This analysis illustrates the feasibility of spatially\nresolved studies of Li-ion dynamics on the sub-10 nanometer level using\nelectromechanical detection.",
        "positive": "Giant Enhancement of Intrinsic Spin Hall Conductivity in $\u03b2$\n  Tungsten via Substitutional Doping: A key challenge in manipulating the magnetization in\nheavy-metal/ferromagnetic bilayers via the spin-orbit torque is to identify\nmaterials that exhibit an efficient charge-to-spin current conversion. Ab\ninitio electronic structure calculations reveal that the intrinsic spin Hall\nconductivity (SHC) for pristine $\\beta$-W is about sixty percent larger than\nthat of $\\alpha$-W. More importantly, we demonstrate that the SHC of $\\beta$-W\ncan be enhanced via Ta alloying. This is corroborated by spin Berry curvature\ncalculations of W$_{1-x}$Ta$_x$ ($x$ $\\sim$ 12.5%) alloys which show a giant\nenhancement of spin Hall angle of up to $\\approx$ $-0.5$. The underlying\nmechanism is the synergistic behavior of the SHC and longitudinal conductivity\nwith Fermi level position. These findings, not only pave the way for enhancing\nthe intrinsic spin Hall effect in $\\beta$-W, but also provide new guidelines to\nexploit substitutional alloying to tailor the spin Hall effect in various\nmaterials."
    },
    {
        "anchor": "Magnetoimpedance effect at the high frequency range for the thin film\n  geometry: Numerical calculation and experiment: The magnetoimpedance effect is a versatile tool to investigate ferromagnetic\nmaterials, revealing aspects on the fundamental physics associated to\nmagnetization dynamics, broadband magnetic properties, important issues for\ncurrent and emerging technological applications for magnetic sensors, as well\nas insights on ferromagnetic resonance effect at non-saturated magnetic states.\nHere, we perform a theoretical and experimental investigation of the\nmagnetoimpedance effect for the thin film geometry in a wide frequency range.\nWe calculate the longitudinal magnetoimpedance for single layered, multilayered\nor exchange biased systems from an approach that considers a magnetic\npermeability model for planar geometry and the appropriate magnetic free energy\ndensity for each structure. From numerical calculations and experimental\nresults found in literature, we analyze the magnetoimpedance behavior, and\ndiscuss the main features and advantages of each structure. To test the\nrobustness of the approach, we directly compare theoretical results with\nexperimental magnetoimpedance measurements obtained in a wide range of\nfrequencies for an exchange biased multilayered film. Thus, we provide\nexperimental evidence to confirm the validity of the theoretical approach\nemployed to describe the magnetoimpedance in ferromagnetic films, revealed by\nthe good agreement between numerical calculations and experimental results.",
        "positive": "Alterferroicity with seesaw-type magnetoelectricity: Primary ferroicities like ferroelectricity and ferromagnetism are essential\nphysical properties of matter. Multiferroics, with coexisting multiple ferroic\norders in a single phase, provide a convenient route to magnetoelectricity.\nEven so, the general trade-off between magnetism and polarity remains\ninevitable, which prevents practicable magnetoelectric cross control in the\nmultiferroic framework. Here an alternative strategy, i.e. the so-called\nalterferroicity, is proposed to circumvent the magnetoelectric exclusiveness,\nwhich exhibits multiple but non-coexisting ferroic orders. The natural\nexclusion between magnetism and polarity, as an insurmountable weakness of\nmultiferroicity, becomes a distinct advantage in alterferroicity, making it an\ninborn rich ore for intrinsic strong magnetoelectricity. The general design\nrules for alterferroic materials rely on the competition between the\ninstabilities of phononic and electronic structures in covalent systems. Based\non primary density functional theory calculations, Ti-based trichalcogenides\nare predicted to be alterferroic candidates, which exhibit unique seesaw type\nmagnetoelectricity. This alterferroicity, as an emerging branch of ferroic\nfamily, re-shapes the framework of magnetoelectricity, going beyond the\nestablished scenario based on multiferroicity."
    },
    {
        "anchor": "Dynamics of magnetic single domain particles embedded in a viscous\n  liquid: Kinetic equations for magnetic nano particles dispersed in a viscous liquid\nare developed and analyzed numerically. Depending on the amplitude of an\napplied oscillatory magnetic field the particles orient their time averaged\nanisotropy axis perpendicular to the applied field for low magnetic field\namplitudes and nearly parallel to the direction of the field for high\namplitudes. The transition between these regions takes place in a narrow field\ninterval. In the low field region the magnetic moment is locked to some crystal\naxis and the energy absorption in an oscillatory driving field is dominated by\nviscous losses associated with particle rotation in the liquid. In the opposite\nlimit the magnetic moment rotates within the particle while its easy axis being\nnearly parallel to the external field direction oscillates. The kinetic\nequations are generalized to include thermal fluctuations. This leads to a\nsignificant increase of the power absorption in the low and intermediate field\nregion with a pronounced absorption peak as function of particle size. In the\nhigh field region, on the other hand, the inclusion of thermal fluctuations\nreduces the power absorption. The illustrative numerical calculations presented\nare performed for magnetic parameters typical for iron oxide.",
        "positive": "Local breaking of the spin-orbit interaction: the microscopic origin of\n  exchange bias in Co/FeMn: Modern magnetic thin film devices owe their success in large part to effects\nemerging from interlayer coupling and exchange interaction at interfaces. A\nprominent example is exchange bias (EB), a magnetic coupling phenomenon found\nin ferromagnet (F)/antiferromagnet (AF) systems. Uncompensated pinned moments\nin the AF couple to the F via the interface causing an additional\nunidirectional anisotropy. As a result, the hysteresis of the F is shifted. The\nexistence of such pinned moments is nowadays accepted although their physical\nnature and origin is still unknown. Here we present a thorough spectroscopic\ninvestigation based on X-ray magnetic circular dichroism which does for the\nfirst time provide direct information about the physics of pinned magnetic\nmoments. Our data clearly shows that the orbital magnetic moment, which is\nusually widely quenched in transition metal systems, is the driving force\nbehind exchange bias in Co/FeMn."
    },
    {
        "anchor": "Stoichiometric growth of high Curie temperature heavily-alloyed GaMnAs: Heavily-alloyed, 100 nm Ga1-xMnxAs (x>0.1) films are obtained via low\ntemperature molecular beam epitaxy utilizing a combinatorial technique which\nallows systematic control of excess arsenic during growth. Reproducible,\noptimized electronic, magnetic and structural properties are found in a narrow\nrange of stoichiometric growth conditions. The Curie temperature of\nstoichiometric material is 150-165 K and independent of x within a large window\nof growth conditions while substitutional Mn content increases linearly,\ncontradicting the prediction of the Zener Model of hole-mediated\nferromagnetism.",
        "positive": "Magnetic properties of hematite revealed by an ab initio parameterized\n  spin model: Hematite is a canted antiferromagnetic insulator, promising for applications\nin spintronics. Here, we present ab initio calculations of the tensorial\nexchange interactions of hematite and use them to understand its magnetic\nproperties by parameterizing a semiclassical Heisenberg spin model. Using\natomistic spin dynamics simulations, we calculate the equilibrium properties\nand phase transitions of hematite, most notably the Morin transition. The\ncomputed isotropic and Dzyaloshinskii--Moriya interactions result in a N\\'eel\ntemperature and weak ferromagnetic canting angle that are in good agreement\nwith experimental measurements. Our simulations show how dipole-dipole\ninteractions act in a delicate balance with first and higher-order on-site\nanisotropies to determine the material's magnetic phase. Comparison with\nspin-Hall magnetoresistance measurements on a hematite single-crystal reveals\ndeviations of the critical behavior at low temperatures. Based on a mean-field\nmodel, we argue that these differences result from the quantum nature of the\nfluctuations that drive the phase transitions."
    },
    {
        "anchor": "Electron density control in tungsten diselenide monolayers via\n  photochlorination: Modulation of the Fermi level using an ultraviolet (UV)-assisted\nphotochemical method is demonstrated in tungsten diselenide monolayers.\nSystematic shifts and relative intensities between charged and neutral exciton\nspecies indicate a progressive and controllable decrease of the electron\ndensity and switch tungsten diselenide from n-type to a p-type semiconductor.\nThe presence of chlorine in the 2D crystal shifts the Fermi level closer to the\nvalence band while the effect can be only partially reversible via continuous\nwave laser rastering process. The presence of chlorine species in the lattice\nis validated by X-ray photoelectron spectroscopy (XPS), and density functional\ntheory (DFT) calculations predict that adsorption of chlorine on the selenium\nvacancy sites leads to p-type doping. The results of our study indicate that\nphotochemical techniques have the potential to enhance the performance of\nvarious 2D materials, making them suitable for potential applications in\noptoelectronics.",
        "positive": "Berezinskii-Kosterlitz-Thouless phases in ultra-thin PbTiO$_3$/SrTiO$_3$\n  superlattices: We study the emergence of Berezinskii-Kosterlitz-Thouless (BKT) phases in\n(PbTiO$_3$)$_3$/(SrTiO$_3$)$_3$ superlattices by means of second-principles\nsimulations. Beyond a threshold tensile epitaxial strain of $\\epsilon = 0.25\n\\%$ the local dipole moments within the superlattices are confined to the\nfilm-plane, and thus the polarization can be effectively considered as\ntwo-dimensional. The analysis of the decay of the dipole-dipole correlation\nwith the distance, together with the study of the density of defects and its\ndistribution as function of temperature, supports the existence of a BKT phase\nin a range of temperature mediating the ordered ferroelectric (stable at low\n$T$), and the disordered paraelectric phase that appears beyond a critical\ntemperature $T_{\\rm BKT}$. This BKT phase is characterized by quasi-long-range\norder (whose signature is a power-law decay of the correlations with the\ndistance), and the emergence of tightly bounded vortex-antivortex pairs whose\ndensity is determined by a thermal activation process. The proposed\nPbTiO$_{3}$/SrTiO$_{3}$ superlattice model and the imposed mechanical boundary\nconditions are both experimentally feasible, opening the door for the first\nexperimental observation of these new topological phases in ferroelectric\nmaterials."
    },
    {
        "anchor": "Modified Z-Phase Formation in a 12% Cr Tempered Martensite Ferritic\n  Steel during Long-Term Creep: The formation of modified Z-phase in a 12Cr1MoV (German grade: X20) tempered\nmartensite ferritic (TMF) steel subjected to interrupted long-term\ncreep-testing at 550$^{\\circ}$C and 120 MPa was investigated. Quantitative\nvolumetric measurements collected from thin-foil and extraction replica samples\nshowed that modified Z-phase precipitated in both the uniformly-elongated gauge\n($f_v$: 0.23 $\\pm$ 0.02 %) and thread regions ($f_v$: 0.06 $\\pm$ 0.01 %) of the\nsample that ruptured after 139 kh. The formation of modified Z-phase was\naccompanied by a progressive dissolution of MX precipitates, which decreased\nfrom ($f_v$: 0.16 $\\pm$ 0.02 %) for the initial state to ($f_v$: 0.03 $\\pm$\n0.01 %) in the uniformly-elongated gauge section of the sample tested to\nfailure. The interparticle spacing of the creep-strengthening MX particles\nincreased from ($\\lambda_{3D}$: 0.55 $\\pm$ 0.05 $\\mu m$) in the initial state\nto ($\\lambda_{3D}$: 1.01 $\\pm$ 0.10 $\\mu m$) for the uniformly-elongated gauge\nsection of the ruptured sample, while the thread region had an interparticle\nspacing of ($\\lambda_{3D}$: 0.60 $\\pm$ 0.05 $\\mu m$). The locally deformed\nfracture region had an increased phase fraction of modified Z-phase ($f_v$:\n0.40 $\\pm$ 0.20 %), which implies that localised creep-strain strongly promotes\nthe formation of modified Z-phase. The modified Z-phase precipitates did not\nform only on prior-austenite grain boundaries and formed throughout the\ntempered martensite ferritic grain structure.",
        "positive": "Structural and Electronic properties of cubic (GaN)$_1$/(ZnO)$_1$\n  superlattice: Modified Becke-Johnson exchange potential: The structural and electronic properties of new structural cubic\n(GaN)$_1$/(ZnO)$_1$ superlattice have been investigated using two different\ntheoretical techniques: the full potential-linearized augmented plane wave\n(FP-LAPW) method and the linear combination of localized pseudo atomic orbital\n(LCPAO). The new modified Becke-Johnson (mBJ) exchange potential is chosen to\nimprove the bandgap of the superlattice and effective masses. The bandgap is\nfound to be slightly indirect and reduced from those of pure GaN and ZnO. The\norigin of this reduction is attributed to the $p-d$ repulsion of the Zn-N\ninterface and the presence of the O $p$ electron. The electron effective mass\nis found to be isotropic. Good agreement is obtained between two used methods\nand with available theoretical and experimental data."
    },
    {
        "anchor": "Photoluminescent SiC tetrapods: Recently, significant research efforts have been made to develop complex\nnanostructures to provide more sophisticated control over the optical and\nelectronic properties of nanomaterials. However, there are only a handful of\nsemiconductors which allow control over their geometry via simple chemical\nprocesses. Here, we present a molecularly seeded synthesis of a complex\nnanostructure, SiC tetrapods, and report on their structural and optical\nproperties. The SiC tetrapods exhibit narrow linewidth photoluminescence at\nwavelengths spanning the visible to near infrared spectral range. Synthesized\nfrom low-toxicity, earth abundant elements, these tetrapods are a compelling\nreplacement for technologically important quantum optical materials that\nfrequently require toxic metals such as Cd and Se. This new, previously unknown\ngeometry of SiC nanostructures is a compelling platform for biolabeling,\nsensing, spintronics and optoelectronics.",
        "positive": "Structure of Fe3Si/Al/Fe3Si thin film stacks on GaAs(001): Fe3Si/Al/Fe3Si/GaAs(001) structures were deposited by molecular-beam epitaxy\nand characterized by transmission and scanning electron microscopy, and x-ray\ndiffraction. The first Fe3Si film on GaAs(001) is growing epitaxially as (001)\noriented single crystal. The subsequent Al film grows almost 111 oriented in a\nfibre texture although the underlying Fe3Si is exactly (001) oriented. The\ngrowth in this orientation is triggered by a thin transition region which is\nformed at the Fe3Si/Al interface. In the end after the growth of the second\nFe3Si layer on top of the Al the final properties of the whole stack depend on\nthe substrate temperature T_S during deposition of the last film. The upper\nFe3Si films are mainly 110 oriented although they are poly-crystalline. At\nlower T_S, around room temperature, all the films retain their original\nstructural properties."
    },
    {
        "anchor": "Superionic states formation in group III oxides irradiated with\n  ultrafast lasers: A number of group III-metal oxides are studied via density functional theory\nin order to establish a possibility of nonthermal transition of these materials\ninto a superionic state. Atomic and electronic properties of the materials are\nanalyzed during the transitions to acquire insights into physical mechanisms\nguiding such transformations. This knowledge is then used to suggest a\ncriterion allowing to predict the possibility of such transitions without\nemploying computationally heavy methods.",
        "positive": "Optimization of nanocomposite materials for permanent magnets by\n  micromagnetic simulations: effect of the intergrain exchange and the hard\n  grains shape: In this paper we perform the detailed numerical analysis of remagnetization\nprocesses in nanocomposite magnetic materials consisting of magnetically hard\ngrains (i.e. grains made of a material with a high magnetocrystalline\nanisotropy) embedded into a magnetically soft phase. Such materials are widely\nused for the production of permanent magnets, because they combine the high\nremanence with the large coercivity. We perform simulations of nanocomposites\nwith Sr-ferrite as the hard phase and Fe or Ni as the soft phase, concentrating\nour efforts on analyzing the effects of ({\\it i}) the imperfect intergrain\nexchange and ({\\it ii}) the non-spherical shape of hard grains. We demonstrate\nthat - in contrast to the common belief - the maximal energy product is\nachieved not for systems with the perfect intergrain exchange, but for\nmaterials where this exchange is substantially weakened. We also show that the\nmain parameters of the hysteresis loop - remanence, coercivity and the energy\nproduct - exhibit non-trivial dependencies on the shape of hard grains, and\nprovide detailed explanations for our results. Simulation predictions obtained\nin this work open new ways for the optimization of materials for permanent\nmagnets."
    },
    {
        "anchor": "Importance of phonon contribution to the free migration energy of the O\n  vacancy in BaZrO3: BaZrO3 exhibits excellent proton conductivity and good high-temperature\nstability. It is therefore a promising electrolyte material for solid oxide\nfuel cells. The stability of BaZrO3 at high temperatures is generally explained\nby the low diffusivity of the O vacancy. Present first-principle\nDensity-Functional-Theory calculations show that the slow migration of the\ndoubly positively charged O vacancy at high temperature cannot be solely caused\nby the ground-state migration energy but by the contribution of phonon\nexcitations to the free migration energy. With increasing temperature, the\neffective barrier for oxygen vacancy migration increases. At about 1000K, which\nis the operating temperature of fuel cells, the calculated O vacancy\ndiffusivity is more than one order of magnitude lower than that determined\nusing solely the ground-state migration barrier. The calculated diffusivity\ndata agree well with experimental results from literature. The present work\nreveals that the high-temperature stability of BaZrO3 is mainly due to the\nphonon contribution to the free migration energy of the O vacancy.",
        "positive": "Magnetoresistance, specific heat and magnetocaloric effect of equiatomic\n  rare-earth transition-metal magnesium compounds: We present a study of the magnetoresistance, the specific heat and the\nmagnetocaloric effect of equiatomic $RET$Mg intermetallics with $RE = {\\rm\nLa}$, Eu, Gd, Yb and $T = {\\rm Ag}$, Au and of GdAuIn. Depending on the\ncomposition these compounds are paramagnetic ($RE = {\\rm La}$, Yb) or they\norder either ferro- or antiferromagnetically with transition temperatures\nranging from about 13 to 81 K. All of them are metallic, but the resistivity\nvaries over 3 orders of magnitude. The magnetic order causes a strong decrease\nof the resistivity and around the ordering temperature we find pronounced\nmagnetoresistance effects. The magnetic ordering also leads to well-defined\nanomalies in the specific heat. An analysis of the entropy change leads to the\nconclusions that generally the magnetic transition can be described by an\nordering of localized $S=7/2$ moments arising from the half-filled $4f^7$\nshells of Eu$^{2+}$ or Gd$^{3+}$. However, for GdAgMg we find clear evidence\nfor two phase transitions indicating that the magnetic ordering sets in\npartially below about 125 K and is completed via an almost first-order\ntransition at 39 K. The magnetocaloric effect is weak for the antiferromagnets\nand rather pronounced for the ferromagnets for low magnetic fields around the\nzero-field Curie temperature."
    },
    {
        "anchor": "Magnetization reversal and anomalous coercive field temperature\n  dependence in MnAs epilayers grown on GaAs(100) and GaAs(111)B: The magnetic properties of MnAs epilayers have been investigated for two\ndifferent substrate orientations: GaAs(100) and GaAs(111). We have analyzed the\nmagnetization reversal under magnetic field at low temperatures, determining\nthe anisotropy of the films. The results, based on the shape of the\nmagnetization loops, suggest a domain movement mechanism for both types of\nsamples. The temperature dependence of the coercivity of the films has been\nalso examined, displaying a generic anomalous reentrant behavior at T$>$200 K.\nThis feature is independent of the substrate orientation and films thickness\nand may be associated to the appearance of new pinning centers due to the\nnucleation of the $\\beta$-phase at high temperatures.",
        "positive": "Synergistic coupling in ab initio-machine learning simulations of\n  dislocations: Ab initio simulations of dislocations are essential to build quantitative\nmodels of material strength, but the required system sizes are often at or\nbeyond the limit of existing methods. Many important structures are thus\nmissing in the training or validation of interatomic potentials, whilst studies\nof dislocation-defect interactions must mitigate the effect of strong periodic\nimage interactions along the line direction. We show how these restrictions can\nbe lifted through the use of linear machine learning potentials in hybrid\nsimulations, where only a subset of atoms are governed by ab initio forces. The\nlinear form is exploited in a constrained retraining procedure, qualitatively\nexpanding the range of training structures for learning and giving precise\nmatching of dislocation core structures, such that lines can cross the\nquantum/classical boundary. We apply our method to fully three dimensional\nstudies of impurity segregation to edge and screw dislocations in tungsten. Our\nretrained potentials give systematically improved accuracy to QM/ML reference\ndata and the three dimensional geometry allows for long-range relaxations that\nqualitatively change impurity-induced core reconstructions compared to\nsimulations using short periodic supercells. More generally, the ability to\ntreat arbitrary sub-regions of large scale simulations with ab initio accuracy\nopens a vast range of previously inaccessible extended defects to quantitative\ninvestigation."
    },
    {
        "anchor": "Comparative study of pyroelectric response of PZT-film/Si,\n  PZT-film/Por-Si/Si and PVDF-film/Si structures: The comparative investigation of pyroelectric response modulation frequency\ndependences of structures of \"polar active film-Si substrate\" type based on PZT\nand PVDF and of structures of \"polar active film - buffer layer - Si substrate\"\ntype based on PZT and porous silicon (por-Si) has been carried out. By\nphotopyroelectric modulation method the thermowave pyroelectric \"under-surface\"\nprobing was performed and amplitude-to-frequency and phase-to-frequency\ndependences of pyroelectric response of investigated systems in the voltage and\ncurrent modes were obtained. By performing the analysis of obtained dependences\nthe thermal diffusivity values of investigated PZT and PVDF films, and also\npor-Si interlayer were estimated. The results of theoretical consideration of\nthe structures under investigation are in a good agreement with the\nexperimental data. The problem of thermal decoupling and self-decoupling from\nposition of chain \"frequency-thickness-material\" and question of complete and\nincomplete thermal linkage are briefly discussed. The obtained results show\nthat a por-Si layer is a suitable material for effective thermal decoupling of\npolar active film and heat removing Si-substrate which realized in significant\nincrease of pyroelectric response value and approach it to that of\ncharacteristic for a free sensitive element.",
        "positive": "Influence of germanium substitution on the structural and electronic\n  stability of the competing vanadium dioxide phases: We present a density-functional theory (DFT) study of the structural,\nelectronic, and chemical bonding behaviour in germanium (Ge)-doped vanadium\ndioxide (VO$_2$). Our motivation is to explain the reported increase of the\nmetal-insulator transition temperature under Ge doping and to understand how\nmuch of the fundamental physics and chemistry behind it can be captured at the\nconventional DFT level. We model doping using a supercell approach, with\nvarious concentrations and different spatial distributions of Ge atoms in\nVO$_2$. Our results suggest that the addition of Ge atoms strongly perturbs the\nhigh-symmetry metallic rutile phase and induces structural distortions that\npartially resemble the dimerization of the experimental insulating structure.\nOur work, therefore, hints at a possible explanation of the observed increase\nin transition temperature under Ge doping, motivating further studies into\nunderstanding the interplay of structural and electronic transitions in VO$_2$."
    },
    {
        "anchor": "Modeling intercalation chemistry with multi-redox reactions by sparse\n  lattice models in disordered rocksalt cathodes: Modern battery materials can contain many elements with substantial site\ndisorder, and their configurational state has been shown to be critical for\ntheir performance. The intercalation voltage profile is a critical parameter to\nevaluate the performance of energy storage. The application of commonly used\ncluster expansion techniques to model the intercalation thermodynamics of such\nsystems from \\textit{ab-initio} is challenged by the combinatorial increase in\nconfigurational degrees of freedom as the number of species grows. Such\nchallenges necessitate efficient generation of lattice models without\nover-fitting and proper sampling of the configurational space under charge\nbalance in ionic systems. In this work, we introduce a combined approach that\naddresses these challenges by (1) constructing a robust cluster-expansion\nHamiltonian using the sparse regression technique, including\n$\\ell_0\\ell_2$-norm regularization and structural hierarchy; and (2)\nimplementing semigrand-canonical Monte Carlo to sample charge-balanced ionic\nconfigurations using the table-exchange method and an ensemble-average\napproach. These techniques are applied to a disordered rocksalt oxyfluoride\nLi$_{1.3-x}$Mn$_{0.4}$Nb$_{0.3}$O$_{1.6}$F$_{0.4}$ (LMNOF) which is part of a\nfamily of promising earth-abundant cathode materials. The simulated voltage\nprofile is found to be in good agreement with experimental data and\nparticularly provides a clear demonstration of the Mn and oxygen contribution\nto the redox potential as a function of Li content.",
        "positive": "Effect of charged impurities on graphene thermoelectric power near the\n  Dirac point: In graphene devices with a varying degree of disorders as characterized by\ntheir carrier mobility and minimum conductivity, we have studied the\nthermoelectric power along with the electrical conductivity over a wide range\nof temperatures. We have found that the Mott relation fails in the vicinity of\nthe Dirac point in high-mobility graphene. By properly taking account of the\nhigh temperature effects, we have obtained good agreement between the Boltzmann\ntransport theory and our experimental data. In low-mobility graphene where the\ncharged impurities induce relatively high residual carrier density, the Mott\nrelation holds at all gate voltages."
    },
    {
        "anchor": "New Candidates for Topological Insulators : Pb-based chalcogenide series: Here, we theoretically predict that the series of Pb-based layered\nchalcogenides, Pb$_n$Bi$_2$Se$_{n+3}$ and Pb$_n$Sb$_2$Te$_{n+3}$, are possible\nnew candidates for topological insulators. As $n$ increases, the phase\ntransition from a topological insulator to a band insulator is found to occur\nbetween $n=2$ and 3 for both series. Significantly, among the new topological\ninsulators, we found a bulk band gap of 0.40eV in PbBi$_2$Se$_4$ which is one\nof the largest gap topological insulators, and that Pb$_2$Sb$_2$Te$_5$ is\nlocated in the immediate vicinity of the topological phase boundary, making its\ntopological phase easily tunable by changing external parameters such as\nlattice constants. Due to the three-dimensional Dirac cone at the phase\nboundary, massless Dirac fermions also may be easily accessible in\nPb$_2$Sb$_2$Te$_5$.",
        "positive": "Coordination and chemical effects on the structural, electronic and\n  magnetic properties in Mn pnictides: Simple structures of MnX binary compounds, namely hexagonal NiAs and\nzincblende, are studied as a function of the anion (X = Sb, As, P) by means of\nthe all-electron FLAPW method within local spin density and generalized\ngradient approximations. An accurate analysis of the structural, electronic and\nmagnetic properties reveals that the cubic structure greatly favours the\nmagnetic alignment in these compounds leading to high magnetic moments and\nnearly half-metallic behaviour for MnSb and MnAs. The effect of the anion\nchemical species is related to both its size and the possible hybridization\nwith the Mn $d$ states; both contributions are seen to hinder the magnitude of\nthe magnetic moment for small and light anions. Our results are in very good\nagreement with experiment - where available - and show that the generalized\ngradient approximation is essential to correctly recover both the equilibrium\nvolume and magnetic moment."
    },
    {
        "anchor": "Surface state scattering by adatoms on noble metals: When surface state electrons scatter at perturbations, such as magnetic or\nnonmagnetic adatoms or clusters on surfaces, an electronic resonance, localized\nat the adatom site, can develop below the bottom of the surface state band for\nboth spin channels. In the case of adatoms, these states have been found very\nrecently in scanning tunneling spectroscopy experiments\\cite{limot,olsson} for\nthe Cu(111) and Ag(111) surfaces. Motivated by these experiments, we carried\nout a systematic theoretical investigation of the electronic structure of these\nsurface states in the presence of magnetic and non-magnetic atoms on Cu(111).\nWe found that Ca and all 3$d$ adatoms lead to a split-off state at the bottom\nof the surface band which is, however, not seen for the $sp$ elements Ga and\nGe. The situation is completely reversed if the impurities are embedded in the\nsurface: Ga and Ge are able to produce a split-off state whereas the 3$d$\nimpurities do not. The resonance arises from the s-state of the impurities and\nis explained in terms of strength and interaction nature (attraction or\nrepulsion) of the perturbing potential.",
        "positive": "Directional mechanical response in the bulk of topological metamaterials: Mechanical metamaterials are those structures designed to convey force and\nmotion in novel and desirable ways. Recently, Kane and Lubensky showed that\nlattices at the point of marginal mechanical stability (Maxwell lattices)\npossess a topological invariant that describes the distribution of floppy,\nzero-energy edge modes. Here, we show that applying force at a point in the\nbulk of these lattices generates a directional mechanical response, in which\nstress or strain is induced only on one side of the force. This provides both a\nbulk metric for mechanical polarization and a design principle to convey\nstresses and strains towards or away from parts of the structure. We also\ncharacterize the effects of removing bonds on the material's structure and\nfloppy modes, establishing a relationship between edge modes and bulk response."
    },
    {
        "anchor": "Modeling the electrical conductivity in BaTiO3 on the basis of\n  first-principles calculations: The dependence of the electrical conductivity on the oxygen partial pressure\nis calculated for the prototypical perovskite $\\Ba\\Ti\\O_3$ based on data\nobtained from first-principles calculations within density functional theory.\nThe equilibrium point defect concentrations are obtained via a self-consistent\ndetermination of the electron chemical potential. This allows to derive charge\ncarrier concentrations for a given temperature and chemical environment and\neventually the electrial conductivity. The calculations are in excellent\nagreement with experimental data if an accidental acceptor dopant level of\n$10^{17}\\,\\cm^{-3}$ is assumed. It is shown that doubly charged oxygen\nvacancies are accountable for the high-temperature $n$-type conduction under\noxygen-poor conditions. The high-temperature $p$-type conduction observed at\nlarge oxygen pressures is due to barium vacancies and titanium-oxygen\ndi-vacancies under Ti and Ba-rich conditions, respectively. Finally, the\nconnection between the present approach and the mass-action law approach to\npoint defect thermodynamics is discussed.",
        "positive": "Mixed-Stacking Few-Layer Graphene as an Elemental Weak Ferroelectric\n  Material: Ferroelectricity (Valasek, J. Phys. Rev. 1921, 17, 475) - a spontaneous\nformation of electric polarisation - is a solid state phenomenon, usually,\nassociated with ionic compounds or complex materials. Here we show that,\natypically for elemental solids, few-layer graphenes can host an equilibrium\nout-of-plane electric polarisation, switchable by sliding the constituent\ngraphene sheets. The systems hosting such effect include mixed-stacking\ntetralayers and thicker (5-9 layers) rhombohedral graphitic films with a twin\nboundary in the middle of a flake. The predicted electric polarisation would\nalso appear in marginally (small-angle) twisted few-layer flakes, where lattice\nreconstruction would give rise to networks of mesoscale domains with\nalternating value and sign of out-of-plane polarisation."
    },
    {
        "anchor": "Influence of Si doping and O2-flow on arc deposited (Al,Cr)2O3 coatings: (Al,Cr)2O3 coatings with Al/(Al+Cr) = 0.5 or Al = 70 at.%, doped with 0, 5 or\n10 at.% Si, were deposited on hard metal and Si(100) substrates to elucidate\nthe influence of Si on the resulting coatings. The chemical analysis of the\ncoatings showed between 3.3 and 7.4 at.% metal fraction Si incorporated into\nall studied coatings depending on cathode Si-composition. The incorporated Si\ncontent does not change significantly with different oxygen flow covering a\nwide range of deposition conditions from low to high O2 flow during growth. The\naddition of Si promotes the metastable B1-like cubic structure over the\nthermodynamically stable corundum structure. The hardness determined by\nnanoindentation of the as-deposited coatings is slightly reduced upon\nSi-incorporation as well as upon increased Al-content. Si is found enriched in\ndroplets but can also be found at a lower content, evenly spread, without\nvisible segregation on the ~5 nm scale, in the actual oxide coating. The\npositive effect of improved cathode erosion upon Si-incorporation has to be\nbalanced against the promotion of the metastable B1-like structure, having\nlower room temperature hardness and inferior thermal stability compared to the\ncorundum structure.",
        "positive": "Ideal barriers to polarization reversal and domain-wall motion in\n  strained ferroelectric thin films: The ideal intrinsic barriers to domain switching in c-phase PbTiO_3 (PTO),\nPbZrO_3 (PZO), and PbZr_{1-x}Ti_xO_3 (PZT) are investigated via\nfirst-principles computational methods. The effects of epitaxial strain on the\natomic structure, ferroelectric response, barrier to coherent domain reversal,\ndomain-wall energy, and barrier to domain-wall translation are studied. It is\nfound that PTO has a larger polarization, but smaller energy barrier to domain\nreversal, than PZO. Consequentially the idealized coercive field is over two\ntimes smaller in PTO than PZO. The Ti--O bond length is more sensitive to\nstrain than the other bonds in the crystals. This results in the polarization\nand domain-wall energy in PTO having greater sensitivity to strain than in PZO.\nTwo ordered phases of PZT are considered, the rock-salt structure and a (100)\nPTO/PZO superlattice. In these simple structures we find that the ferroelectric\nproperties do not obey Vergard's law, but instead can be approximated as an\naverage over individual 5-atom unit cells."
    },
    {
        "anchor": "Magnetic properties of poly(trimethylene\n  terephthalate-block-poly(tetramethylene oxide) copolymer nanocomposites\n  reinforced by graphene oxide-Fe3O4 hybrid nanoparticles: Thermoplastic elastomeric nanocomposites based on poly(trimethylene\nterephthalate-block-poly(tetramethylene oxide) copolymer (PTT-PTMO) and\ngraphene oxide-Fe3O4 nanoparticle hybrid were prepared by in situ\npolymerization. Superparamagnetic GO-Fe3O4 hybrid nanoparticles before\nintroducing to elastomeric matrix were characterized by X-ray photoelectron\nspectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TGA)\nand scanning electron microscopy (SEM). The effect of loading (0.3 and 0.5 wt%)\nof GO-Fe3O4 nanoparticle hybrid on the phase structure, tensile and magnetic\nproperties of synthesized nanocomposites was investigated. The phase structure\nof nanocomposites was evaluated by differential scanning calorimetry (DSC) and\ndynamic mechanical thermal analysis (DMTA). Dispersion of GO-Fe3O4\nnanoparticles in elastomeric matrix was evaluated by transmission electron\nmicroscopy (TEM). Magnetic properties of GO-Fe3O4 nanoparticle hybrid and\nnanocomposites with their content were characterized by using two different\ntechniques: dc SQUID magnetization measurements as a function of temperature\n(from 2 to 300 K) and external magnetic field and ferromagnetic resonance (FMR)\nat microwave frequency.",
        "positive": "Adsorption of water at the SrO surface of ruthenates: Although perovskite oxides hold promise in applications ranging from solid\noxide fuel cells to catalysts, their surface chemistry is poorly understood at\nthe molecular level. Here we follow the formation of the first monolayer of\nwater at the (001) surfaces of Sr$_{n+1}$Ru$_n$O$_{3n+1}$ ($n$ = 1, 2) using\nlow-temperature scanning tunnelling microscopy, X-ray photoelectron\nspectroscopy, and density functional theory. These layered perovskites cleave\nbetween neighbouring SrO planes, yielding almost ideal, rocksalt-like surfaces.\nAn adsorbed monomer dissociates and forms a pair of hydroxide ions. The OH\nstemming from the original molecule stays trapped at Sr-Sr bridge positions,\ncircling the surface OH with a measured activation energy of 187 $\\pm$ 10 meV.\nAt higher coverage, dimers of dissociated water assemble into one-dimensional\nchains and form a percolating network where water adsorbs molecularly in the\ngaps. Our work shows the limitations of applying surface chemistry concepts\nderived for binary rocksalt oxides to perovskites."
    },
    {
        "anchor": "Electron Emission Energy Barriers and Stability of $Sc_2O_3$ with\n  Adsorbed Ba and Ba-O: In this study we employ Density Functional Theory (DFT) methods to\ninvestigate the surface energy barrier for electron emission (surface barrier)\nand thermodynamic stability of Ba and Ba-O species adsorption under conditions\nof high temperature (approximately 1200 K) and low pressure (approximately\n$10^{-10}$ Torr) on the low index surfaces of bixbyite $Sc_2O_3$. The role of\nBa in lowering the cathode surface barrier is investigated via adsorption of\natomic Ba and Ba-O dimers, where the highest simulated dimer coverage\ncorresponds to a single monolayer film of rocksalt BaO. The change of the\nsurface barrier of a semiconductor due to adsorption of surface species is\ndecomposed into two parts: a surface dipole component and doping component. The\nlowest surface barrier with atomic Ba on $Sc_2O_3$ was found to be 2.12 eV and\n2.04 eV for the (011) and (111) surfaces at 3 and 1 Ba atoms per surface unit\ncell (0.250 and 0.083 Ba per surface O), respectively. The lowest surface\nbarrier for Ba-O on $Sc_2O_3$ was found to be 1.21 eV on (011) for a 7 Ba-O\ndimer-per-unit-cell coverage (0.583 dimers per surface O). Generally, we found\nthat Ba in its atomic form on $Sc_2O_3$ surfaces is not stable relative to bulk\nBaO, while Ba-O dimer coverages between 3 to 7 Ba-O dimers per (011) surface\nunit cell (0.250 to 0.583 dimers per surface O) produce stable structures\nrelative to bulk BaO. Ba-O dimer adsorption on $Sc_2O_3$ (111) surfaces was\nfound to be unstable versus BaO over the full range of coverages studied.\nInvestigation of combined n-type doping and surface dipole modification showed\nthat their effects interact to yield a reduction less than the two\ncontributions would yield separately.",
        "positive": "Sound propagation and force chains in granular materials: Granular materials are inherently heterogeneous, leading to challenges in\nformulating accurate models of sound propagation. In order to quantify acoustic\nresponses in space and time, we perform experiments in a photoelastic granular\nmaterial in which the internal stress pattern (in the form of force chains) is\nvisible. We utilize two complementary methods, high-speed imaging and\npiezoelectric transduction, to provide particle-scale measurements of both the\namplitude and speed of an acoustic wave in the near-field regime. We observe\nthat the wave amplitude is on average largest within particles experiencing the\nlargest forces, particularly in those chains radiating away from the source,\nwith the force-dependence of this amplitude in qualitative agreement with a\nsimple Hertzian-like model of particle contact area. In addition, we are able\nto directly observe rare transient force chains formed by the opening and\nclosing of contacts during propagation. The speed of the leading edge of the\npulse is in quantitative agreement with predictions for one-dimensional chains,\nwhile the slower speed of the peak response suggests that it contains waves\nwhich have travelled over multiple paths even within just this near-field\nregion. These effects highlight the importance of particle-scale behaviors in\ndetermining the acoustical properties of granular materials."
    },
    {
        "anchor": "Do methanethiol adsorbates on the Au(111) surface dissociate?: The interaction of methanethiol molecules CH$_{3}$SH with the Au(111) surface\nis investigated, and it is found for the first time that the S-H bond remains\nintact when the methanethiol molecules are adsorbed on the regular Au(111)\nsurface. However, it breaks if defects are present in the Au(111) surface. At\nlow coverage, the fcc region is favored for S atom adsorption, but at saturated\ncoverage the adsorption energies at various sites are almost iso-energetic. The\npresented calculations show that a methanethiol layer on the regular Au(111)\nsurface does not dimerize.",
        "positive": "The gauge theory of dislocations: conservation and balance laws: We derive conservation and balance laws for the translational gauge theory of\ndislocations by applying Noether's theorem. We present an improved\ntranslational gauge theory of dislocations including the dislocation density\ntensor and the dislocation current tensor. The invariance of the variational\nprinciple under the continuous group of transformations is studied. Through\nLie's-infinitesimal invariance criterion we obtain conserved translational and\nrotational currents for the total Lagrangian made up of an elastic and\ndislocation part. We calculate the broken scaling current. Looking only on one\npart of the whole system, the conservation laws are changed into balance laws.\nBecause of the lack of translational, rotational and dilatation invariance for\neach part, a configurational force, moment and power appears. The corresponding\nJ, L and M integrals are obtained. Only isotropic and homogeneous materials are\nconsidered and we restrict ourselves to a linear theory. We choose constitutive\nlaws for the most general linear form of material isotropy. Also we give the\nconservation and balance laws corresponding to the gauge symmetry and the\naddition of solutions. From the addition of solutions we derive a reciprocity\ntheorem for the gauge theory of dislocations. Also, we derive the conservation\nlaws for stress-free states of dislocations."
    },
    {
        "anchor": "Stability and molecular pathways to the formation of spin defects in\n  silicon carbide: Spin defects in wide-bandgap semiconductors provide a promising platform to\ncreate qubits for quantum technologies. Their synthesis, however, presents\nconsiderable challenges, and the mechanisms responsible for their generation or\nannihilation are poorly understood. Here, we elucidate spin defect formation\nprocesses in a binary crystal for a key qubit candidate--the divacancy complex\n(VV) in silicon carbide (SiC). Using atomistic models, enhanced sampling\nsimulations, and density functional theory calculations, we find that VV\nformation is a thermally activated process that competes with the conversion of\nsilicon ($V_{Si}$) to carbon monovacancies ($V_{C}$), and that VV reorientation\ncan occur without dissociation. We also find that increasing the concentration\nof $V_{Si}$ relative to $V_{C}$ favors the formation of divacancies. Moreover,\nwe identify pathways to create spin defects consisting of antisite-double\nvacancy complexes and determine their electronic properties. The detailed view\nof the mechanisms that underpin the formation and dynamics of spin defects\npresented here may facilitate the realization of qubits in an industrially\nrelevant material.",
        "positive": "Ternary Tetradymite Compounds as Topological Insulators: Ternary tetradymites Bi2Te2S, Bi2Te2Se and Bi2Se2Te are found to be stable,\nbulk topological insulators via theory, showing band inversion between group V\nand VI pz orbitals. We identify Bi2Se2Te as a good candidate to study massive\nDirac Fermions, with a (111) cleavage-surface-derived Dirac point (DP) isolated\nin the bulk band gap at the Fermi energy Ef like Bi2Se3 but with a spin texture\nalterable by layer chemistry. In contrast, Bi2Te2S and Bi2Te2Se (111) behave\nlike Bi2Te3, with a DP below Ef buried in bulk bands. Bi2Te2S offers large bulk\nresistivity needed for devices."
    },
    {
        "anchor": "High stability of faceted nanotubes and fullerenes of multi-phase\n  layered phosphorus: A computational study: We present a paradigm in constructing very stable, faceted nanotube and\nfullerene structures by laterally joining nanoribbons or patches of different\nplanar phosphorene phases. Our ab initio density functional calculations\nindicate that these phases may form very stable, non-planar joints. Unlike\nfullerenes and nanotubes obtained by deforming a single-phase planar monolayer\nat substantial energy penalty, we find faceted fullerenes and nanotubes to be\nnearly as stable as the planar single-phase monolayers. The resulting rich\nvariety of polymorphs allows to tune the electronic properties of phosphorene\nnanotubes (PNTs) and fullerenes not only by the chiral index, but also by the\ncombination of different phosphorene phases. In selected PNTs, a\nmetal-insulator transition may be induced by strain or changing the number of\nwalls.",
        "positive": "Structure, Thermodynamic and Electronic Properties of Carbon-Nitrogen\n  Cubanes and Protonated Polynitrogen Cations: Energy generation and storage are at the center of modern civilization.\nEnergetic materials constitute quite a large class of compounds with a high\namount of stored chemical energy that can be released. We hereby use a\ncombination of quantum chemistry methods to investigate feasibility and\nproperties of carbon-nitrogen cubanes and multi-charged polynitrogen cations in\nthe context of their synthesis and application as unprecedented energetic\nmaterials. We show that the stored energy increases gradually with the nitrogen\ncontent increase. Nitrogen-poor cubanes retain their stabilities in vacuum,\neven at elevated temperatures. Such molecules will be probably synthesized at\nsome point. In turn, polynitrogen cations are highly unstable, except N8H+,\ndespite they are isoelectronic to all-carbon cubane. Kinetic stability of the\ncation decays drastically as its total charge increases. High-level\nthermodynamic calculations revealed that large amounts of energy are liberated\nupon decompositions of polynitrogen cations, which produce molecular nitrogen,\nacetylene, and protons. The present results bring a substantial insights to the\ndesign of novel high energy compounds."
    },
    {
        "anchor": "DeePore: a deep learning workflow for rapid and comprehensive\n  characterization of porous materials: DeePore is a deep learning workflow for rapid estimation of a wide range of\nporous material properties based on the binarized micro-tomography images. By\ncombining naturally occurring porous textures we generated 17700 semi-real 3-D\nmicro-structures of porous geo-materials with size of 256^3 voxels and 30\nphysical properties of each sample are calculated using physical simulations on\nthe corresponding pore network models. Next, a designed feed-forward\nconvolutional neural network (CNN) is trained based on the dataset to estimate\nseveral morphological, hydraulic, electrical, and mechanical characteristics of\nthe porous material in a fraction of a second. In order to fine-tune the CNN\ndesign, we tested 9 different training scenarios and selected the one with the\nhighest average coefficient of determination (R^2) equal to 0.885 for 1418\ntesting samples. Additionally, 3 independent synthetic images as well as 3\nrealistic tomography images have been tested using the proposed method and\nresults are compared with pore network modelling and experimental data,\nrespectively. Tested absolute permeabilities had around 13 % relative error\ncompared to the experimental data which is noticeable considering the accuracy\nof the direct numerical simulation methods such as Lattice Boltzmann and Finite\nVolume. The workflow is compatible with any physical size of the images due to\nits dimensionless approach and can be used to characterize large-scale 3-D\nimages by averaging the model outputs for a sliding window that scans the whole\ngeometry.",
        "positive": "Observation of Interband Two-Photon Absorption Saturation in CdS\n  Nanocrystals: We report the observation of interband two-photon absorption (TPA) saturation\nin cadmium sulfide nanocrystals (CdS NCs) under intense femtosecond laser\nexcitation with 1.6-eV photon energy. The observation has been compared to\ninterband TPA saturation in bulk CdS under the same experimental conditions. By\nusing both Z-scan technique and transient absorption measurement, the\nsaturation intensity has been determined to be 190 GW/cm^2 for CdS NCs of 4-nm\ndiameter, which shows two orders of magnitude greater than that for CdS bulk\ncrystal. The results are in agreement with an inhomogeneously-broadened,\nsaturated TPA model."
    },
    {
        "anchor": "Atomic forces from Dirac-Kohn-Sham equations: Implementation in flexible\n  (APW+lo/LAPW)+LO basis set: Atomic forces formulation based on the Dirac-Kohn-Sham equation and flexible\n(APW+lo/LAPW)+LO basis set is presented. The formulation was implemented in the\ncode FlapwMBPT and allows a user to easily switch between different basis\nfunctions of the augmentation type (APW or LAPW) and between different kind of\nlocal orbitals. Similar to the work (Phys.Rev.B 91 (2015) 035105), the\nimplementation takes into account small discontinuities of the wave functions,\ndensity, and potential at the muffin-tin sphere boundaries. Applications to the\nmaterials with strong relativistic effects, such as $\\alpha$-Uranium,\nPuCoGa$_{5}$, and FePt, demonstrate robustness of the method. Comparison of the\ncalculated forces with the ones obtained by numerical differentiation of the\nfree energy shows close agreement with deviations about 0.1\\% or less.",
        "positive": "Light-induced size changes in BiFeO3 crystals: Multifunctional oxides are promising materials because of their fundamental\nphysical properties as well as their potential in applications1. Among these\nmaterials, multiferroics exhibiting ferroelectricity and magnetism are good\ncandidates for spin electronic applications using the magnetoelectric effect,\nwhich couples magnetism and ferroelecticity. Furthermore, because\nferroelectrics are insulators with a reasonable bandgap, photons can\nefficiently interact with electrons leading to photoconduction or photovoltaic\neffects. However, until now, coupling of light with mechanical degrees of\nfreedom has been elusive, although ferroelasticity is a well-known property of\nthese materials. Here, we report on the observation, for the first time, of a\nsubstantial visiblelight- induced change in the dimensions of BiFeO3 crystals\nat room temperature. The relative light-induced photostrictive effect is of the\norder of 10e-5 with response times below 0.1s. It depends on the polarization\nof incident light as well as applied magnetic fields. This opens the\nperspective of combining mechanical, magnetic, electric and optical\nfunctionalities in future generations of remote switchable devices."
    },
    {
        "anchor": "Molecular theory of graphene: Odd electrons of benzenoid units and correlation of these electrons having\ndifferent spins are the main concepts of the molecular theory of graphene. In\ncontrast to the theory of aromaticity, the molecular theory is based on the\nfact that odd electrons with different spins occupy different places in the\nspace so that the configuration interaction becomes the central point of the\ntheory. Consequently, a multi-determinant presentation of the wave function of\nthe system of weakly interacting odd electrons is absolutely mandatory on the\nway of the theory realization at the computational level. However, the efficacy\nof the available CI computational techniques is quite restricted in regards\nlarge polyatomic systems, which does not allow performing extensive\ncomputational experiments. Facing the problem, computationists have addressed\nto standard single-determinant ones albeit not often being aware of how correct\nare the obtained results. The current chapter presents the molecular theory of\ngraphene in terms of single-determinant computational schemes and discloses how\nreliable information about electron-correlated system can be obtained by using\neither UHF or UDFT computational schemes.",
        "positive": "Polarized neutron reflectometry study of Fe16N2 with Giant Saturation\n  Magnetization prepared by N Inter-diffusion in Annealed Fe-N Thin Films: We report a synthesis route to grow iron nitride thin films with giant\nsaturation magnetization (Ms) through an N inter-diffusion process. By post\nannealing Fe/Fe-N structured films grown on GaAs(001) substrates, nitrogen\ndiffuses from the over-doped amorphous-like Fe-N layer into strained\ncrystalline Fe layer and facilitates the development of metastable Fe16N2\nphase. As explored by polarized neutron reflectometry, the depth-dependent Ms\nprofile can be well described by a model with the presence of a giant Ms up to\n2360 emu/cm3 at near-substrate interface, corresponding to the strained regions\nof these annealed films. This is much larger than the currently known limit\n(Fe65Co35 with Ms \\sim 1900 emu/cm3). The present synthesis method can be used\nto develop writer materials for future magnetic recording application."
    },
    {
        "anchor": "Synchrotron X-ray tomography investigation of 3D morphology of\n  intermetallic phases and pores and their effect on the mechanical properties\n  of cast Al-Cu alloys: The influence of Fe content on the three-dimensional (3D) morphology of\nFe-rich intermetallic phases (Fe phases), Al2Cu, and pores and mechanical\nproperties of cast Al-5.0Cu-0.6Mn alloys with 0.5 and 1.0 wt. % Fe are\ncharacterized using synchrotron X-ray tomography and a tensile test. The\nresults show that both Fe phases and Al2Cu exhibit a complex 3D network\nstructure, and the pores are irregular with complex interconnected and\nnear-globular shape. As the Fe content increases from 0.5 % to 1.0 %, the\nvolume fraction and equivalent diameter of Fe phases decrease, whereas both\ntheir interconnectivities decrease. Skeletonization analysis shows that the\nChinese-script-shaped Fe phase is compacted than the plate-like Fe phases. The\nequivalent diameter and sphericity of pores vary with Fe content, and their\nrelationships follow exponential functions, Y = 7.14*X-1.29 and Y =\n7.06*X-1.20, respectively. The addition of Fe results in a decrease in the\nultimate tensile strength and elongation from 223.7 MPa to 199.8 MPa and from\n5.51 % to 3.64 %, respectively, owing to increasing volume fraction of\nsharp-edged Fe phases and pores, resulting in stress concentration during\ntensile test.",
        "positive": "Optimized hydrogen sensing properties of nanocomposite NiO:Au thin films\n  grown by dual Pulsed Laser Deposition: Nanocomposite NiO:Au thin films, formed by gold nanoparticles embedded in a\nnickel oxide matrix, have been grown by reactive pulsed laser deposition\n(R-PLD). Two actively synchronized nanosecond laser sources, a KrF excimer\nlaser (248 nm) and a Nd:YAG laser (355 nm), were used for the simultaneous\nablation of nickel and gold targets in oxygen ambient. The morphology,\ncomposition, and optical properties of the obtained nanocomposites were\ninvestigated and were found to correlate with the concentration of Au\nnanoparticles. Further, the NiO:Au nanocomposites have been tested as hydrogen\nsensors. Embedding Au nanoparticles into the NiO film matrix reduced the\nsensors operating temperature and improved their performance by orders of\nmagnitude."
    },
    {
        "anchor": "Fermi level and bands offsets determination in insulating (Ga,Mn)N/GaN\n  structures: The Fermi level position in (Ga,Mn)N has been determined from the\nperiod-analysis of GaN-related Franz-Keldysh oscillation obtained by\ncontactless electroreflectance in a series of carefully prepared by molecular\nbeam epitaxy GaN/Ga1-xMnxN/GaN(template) bilayers of various Mn concentration\nx. It is shown that the Fermi level in (Ga,Mn)N is strongly pinned in the\nmiddle of the band gap and the thickness of the depletion layer is negligibly\nsmall. For x > 0.1% the Fermi level is located about 1.25 - 1.55 eV above the\nvalence band, that is very close to, but visibly below the Mn-related Mn2+/Mn3+\nimpurity band. The accumulated data allows us to estimate the Mn-related band\noffsets at the (Ga,Mn)N/GaN interface. It is found that most of the band gap\nchange in (Ga,Mn)N takes place in the valence band on the absolute scale and\namounts to -0.028+-0.008 eV/% Mn. The strong Fermi level pinning in the middle\nof the band gap, no carrier conductivity within the Mn-related impurity band,\nand a good homogeneity enable a novel functionality of (Ga,Mn)N as a\nsemi-insulating buffer layers for applications in GaN-based heterostuctures.",
        "positive": "Dielectric properties of nanoconfined water from ab initio\n  thermopotentiostat molecular dynamics: We discuss how to include our recently proposed thermopotentiostat technique\n[Phys. Rev. Lett. 126, 136803 (2021)] into any existing ab initio molecular\ndynamics (AIMD) package. Using thermopotentiostat AIMD simulations in the\ncanonical NVT{\\Phi} ensemble at constant electrode potential, we compute the\npolarization bound charge and dielectric response of interfacial water from\nfirst principles."
    },
    {
        "anchor": "Strong nonlinear optical response of graphene flakes measured by\n  four-wave mixing: We present the first experimental investigation of nonlinear optical\nproperties of graphene flakes. We find that at near infrared frequencies a\ngraphene monolayer exhibits a remarkably high third-order optical nonlinearity\nwhich is practically independent of the wavelengths of incident light. The\nnonlinear optical response can be utilized for imaging purposes, with image\ncontrasts of graphene which are orders of magnitude higher than those obtained\nusing linear microscopy.",
        "positive": "Stacking control in graphene-based materials: a promising way for\n  fascinating physical properties: Graphene, defined as a single atomic plane of graphite, is a semimetal with\nsmall overlap between the valence and the conduction bands. The stacking of\ngraphene up to several atomic layers can produce diverse physical properties,\ndepending on the stacking way. The bilayer graphene is also a semimetal,\nadopting the AB-stacked (or Bernal-stacked) structure or the rare AA-stacked\nstructure. The trilayer or a few layer graphene (FLG) can be semimetal or\nsemiconductor, depending on whether it takes Bernal (ABA) stacking or\nrhombohedral (ABC) stacking. We will give a perspective on the recent two mild\napproaches to control the stacking via local transition from ABC stacking into\nABA stacking. It is believed that with the rapid development of graphene-based\nmaterials, these techniques for stacking control can be used for more complex\nstructure to fulfill fascinating properties and devices."
    },
    {
        "anchor": "Appearance of room temperature ferromagnetism in Cu-doped\n  TiO$_{2-\u03b4}$ films: In recent years there has been an intense search for room temperature\nferromagnetism in doped dilute semiconductors, which have many potentially\napplications in spintronics and optoelectronics. We report here the unexpected\nobservation of significant room temperature ferromagnetism in a semiconductor\ndoped with nonmagnetic impurities, Cu-doped TiO$_2$ thin films grown by Pulsed\nLaser Deposition. The magnetic moment, calculated from the magnetization\ncurves, resulted surprisingly large, about 1.5 $\\mu_B$ per Cu atom. A large\nmagnetic moment was also obtained from ab initio calculations using the\nsupercell method for TiO$_2$ with Cu impurities, but only if an oxygen vacancy\nin the nearest-neighbour shell of Cu was present. This result suggests that the\nrole of oxygen vacancies is crucial for the appearance of ferromagnetism. The\ncalculations also predict that Cu doping favours the formation of oxygen\nvacancies.",
        "positive": "Correlative Theoretical and Experimental Study of the Polycarbonate | X\n  Interfacial Bond Formation (X = AlN, TiN, TiAlN) during Magnetron Sputtering: To understand the interfacial bond formation between polycarbonate (PC) and\nmagnetron-sputtered metal nitride thin films, PC | X interfaces (X = AlN, TiN,\nTiAlN) are comparatively investigated by ab initio simulations as well as X-ray\nphotoelectron spectroscopy. The simulations predict significant differences at\nthe interface, as N and Ti form bonds with all functional groups of the\npolymer, while Al reacts selectively only with the carbonate group of pristine\nPC. In good agreement with simulations, experimental data reveal that the PC |\nAlN and the PC | TiAlN interfaces are mainly defined by interfacial C-N bonds,\nwhereas for PC | TiN, the interface formation is also characterized by numerous\nC-Ti and (C-O)-Ti bonds. Bond strength calculations combined with the measured\ninterfacial bond density indicate the strongest interface for PC | TiAlN\nfollowed by PC | AlN, whereas the weakest is predicted for PC | TiN due to its\nlower density of strong interfacial C-N bonds. This study shows that the\nemployed computational strategy enables prediction of the interfacial bond\nformation between PC and metal nitrides and that it is reasonable to assume\nthat the research strategy proposed herein can be readily adapted to other\norganic | inorganic interfaces."
    },
    {
        "anchor": "Structural and electronic properties of the metal-metal intramolecular\n  junctions of single-walled carbon nanotubes: Several intramolecular junctions (IMJs) connecting two metallic (11, 8) and\n(9, 6) carbon nanotubes along their common axis have been realized by using a\nlayer-divided technique to the nanotubes and introducing the topological\ndefects. Atomic structure of each IMJ configuration is optimized with a\ncombination of density-functional theory (DFT) and the universal force field\n(UFF) method, based upon which a four-orbital tight-binding calculation is made\non its electronic properties. Different topological defect structures and their\ndistributions on the IMJ interfaces have been found, showing decisive effects\non the localized density of states, while the sigma-pi coupling effect is\nnegligible near Fermi energy (EF). Finally, a new IMJ model has been proposed,\nwhich probably reflects a real atomic structure of the M-M IMJ observed in the\nexperiment [Science 291, 97 (2001)].",
        "positive": "Transformation process of the magnetron-sputtered Ag$_2$O film in\n  hydrogen annealing: The current paper mainly addresses the effect of the hydrogen partial\npressure on the microstructure and transformation of the Ag$_2$O film. The\ntransformation process and mechanism were also analyzed in detail. Increasing\nthe hydrogen partial pressure can accelerate the transformation of Ag$_2$O to\nAg and lower the critical transformation temperature of the film due to the\nenhanced hydrogen reduction, and to both of the lowered activation energy of\nthe reaction of Ag$_2$O with hydrogen and enhanced lattice strain of the\nAg$_2$O film, respectively. Hydrogen-involved reaction in the whole hydrogen\nannealing process is mainly hydrogen reduction reaction with Ag$_2$O. The\ndiffusion of hydrogen and gaseous H$_2$O molecules is accompanied with the\nwhole hydrogen annealing process."
    },
    {
        "anchor": "Quantum corrections to the spin-wave spectrum of La$_2$CuO$_4$ in an\n  external magnetic field: The effects of quantum fluctuations on the magnetic field dependence of the\nspin-wave gaps in the lamellar antiferromagnet La$_2$CuO$_4$ are considered.\nNonlinear corrections to the spin-wave spectrum are calculated to leading order\nin 1/S, where $S$ is the localized spin. The nearest-neighbor exchange\ninteractions between the Cu spins as well as the Dzyaloshinskii-Moriya\ninteractions are taken into account. Using the experimental values of the\ncomponents of the $g$-factor tensor, we get a satisfactory agreement with the\nexperimental results for the field dependence of the gaps by Gozar {\\it et al.}\n[Phys. Rev. Lett. {\\bf 93}, 027001 (2004)], and obtain consistent values of the\nin-plane and inter-plane coupling constants. The field dependence of the\ndispersion of spin waves propagating perpendicular to the CuO$_2$ planes is\nalso discussed.",
        "positive": "Magnetic anisotropy induced by crystal distortion in Ge1-xMn\n  xTe/PbTe//KCl (001) ferromagnetic semiconductor layers: Ferromagnetic resonance (FMR) study of magnetic anisotropy is presented for\nthin layers of IV-VI diluted magnetic semiconductor Ge1-xMn xTe with x=0.14\ngrown by molecular beam epitaxy (MBE) on KCl (001) substrate with a thin PbTe\nbuffer. Analysis of the angular dependence of the FMR resonant field reveals\nthat an easy magnetization axis is located near to the normal to the layer\nplane and is controlled by two crystal distortions present in these\nrhombohedral Ge1-xMnxTe layers: the ferroelectric distortion with the relative\nshift of cation and anion sub-lattices along the [111] crystal direction and\nthe biaxial in-plane, compressive strain due to thermal mismatch."
    },
    {
        "anchor": "Inert gas as electronic impurity in semiconductors: The case for active\n  infrared absorption in silicon: Inert (noble gas) elements are extremely inactive to surrounding chemical\nenvironment and are frequently employed as protective gas in various\nsemiconductor fabrication processes. In this work, we surprisingly discover\nthat high doses of argon up to $10^{17}-10^{20} cm^{-3}$ can be measured in\nsilicon exposed by laser pulses even after 1300 days. First-principles\ncalculations and molecular dynamics identify a unique argon-locking-vacancy\n(ALV) defect atomic model in silicon. The ALV defect is dynamically robust in\ncontrast to the frequently moving pure Si vacancy. While argon is chemically\ninert, it readily modulates defect states of the occupied vacancy via steric\nrepulsion and rattling motions, leading to significant band splitting within\nbandgap and thus strong infrared absorptions. Moreover, the repulsion between\nsubstitutional argon and dangling bonds results in shallow donors which\nexplains the confusion of enhanced n-type carriers in experiments. The work\npaves a way of using noble gas element to produce active infrared absorption\nsource for the non-heteroepitaxy photonic detectors directly on silicon wafer\nat infrared communication wavelength.",
        "positive": "Physics-Based Machine-Learning Approach for Modeling the\n  Temperature-Dependent Yield Strengths of Medium- or High-Entropy Alloys: Machine learning is becoming a powerful tool to predict temperature-dependent\nyield strengths (YS) of structural materials, particularly for\nmulti-principal-element systems. However, successful machine-learning\npredictions depend on the use of reasonable machine-learning models. Here, we\npresent a comprehensive and up-to-date overview of a bilinear log model for\npredicting temperature-dependent YS of medium-entropy or high-entropy alloys\n(MEAs or HEAs). In this model, a break temperature, Tbreak, is introduced,\nwhich can guide the design of MEAs or HEAs with attractive high-temperature\nproperties. Unlike assuming black-box structures, our model is based on the\nunderlying physics, incorporated in form of a priori information. A technique\nof global optimization is employed to enable the concurrent optimization of\nmodel parameters over low- and high-temperature regimes, showing that the break\ntemperature is consistent across YS and ultimate strength for a variety of HEA\ncompositions. A high-level comparison between YS of MEAs/HEAs and those of\nnickel-based superalloys reveal superior strength properties of selected\nrefractory HEAs. For reliable operations, the temperature of a structural\ncomponent, such as a turbine blade, made from refractory alloys may need to\nstay below Tbreak. Once above Tbreak, phase transformations may start taking\nplace, and the alloy may begin losing structural integrity."
    },
    {
        "anchor": "Nanomanufacturing of titania interfaces with controlled structural and\n  functional properties by supersonic cluster beam deposition: Great emphasis is placed on the development of integrated approaches for the\nsynthesis and the characterization of ad hoc nanostructured platforms, to be\nused as templates with controlled morphology and chemical properties for the\ninvestigation of specific phenomena of great relevance for technological\napplications in interdisciplinary fields such as biotechnology, medicine and\nadvanced materials. Here we discuss the crucial role and the advantages of thin\nfilm deposition strategies based on cluster-assembling from supersonic cluster\nbeams. We select cluster-assembled nanostructured titania (ns-TiO2) as a case\nstudy to demonstrate that accurate control over morphological parameters can be\nroutinely achieved, and consequently over several relevant interfacial\nproperties and phenomena, like surface charging in a liquid electrolyte, and\nproteins and nanoparticles adsorption.",
        "positive": "Air filtration from sarin/air mixture by porous graphene-oxide\n  membranes: a molecular dynamics study: Sarin is a very lethal synthetic organophosphorated compound that inhibits\nthe nervous system muscle control. Although not used as a chemical weapon\nanymore, it still worries the authorities regarding possible use by terrorists.\nMost of the studies about sarin are theoretical/computational due to its high\nlethality and are concentrated in its detection and degradation. Few studies\nare about air filtration from sarin gas. Here, the potential of graphene\noxide-based membranes to filter air from sarin/air mixtures is investigated by\nclassical molecular dynamics simulations. Membranes formed by one and two\nnanosheets of porous reduced graphene oxide (rGO) were considered. The passage\nof sarin and air molecules through these membranes from a highly concentrated\nregion to an empty one, is evaluated as a function of temperature and sarin/air\nrelative concentration. Sarin molecules are shown to be trapped by hydroxyl and\ncarboxyl chemical groups in the nanosheet, while a considerable passage of air\nmolecules (N$_2$, O$_2$ and Ar) through the membranes was verified. The results\nshow the capacity of the rGO membranes to retain sarin from passing through,\neven at high temperatures, thus indicating their potential to be used as a\nfilter for sarin gas."
    },
    {
        "anchor": "Dimensional cross-over of the bandgap transition in\n  quasi-two-dimensional MoS2: The anisotropy of the electronic transition is an important physical property\nnot only determining the materials' optical property, but also revealing the\nunderlying character of the electronic states involved. Here we used\nmomentum-resolved electron energy-loss spectroscopy to study the evolution of\nthe anisotropy of the electronic transition involving the low energy valence\nelectrons in the free-standing MoS2 systems as the layer thickness was reduced\nto monolayer. We used the orientation and the spectral-density analysis to show\nthat indirect to direct band-gap transition is accompanied by a three- to\ntwo-dimensional anisotropy cross-over. The result provides a logical\nexplanation for the large sensitivity of indirect transition to the change of\nthickness compared with that for direct transition. By tracking the energy of\nindirect transition, we also revealed the asymmetric response of the valence\nband and conduction band to the quantum confinement effect. Our results have\nimplication for future optoelectronic applications of atomic thin MoS2.",
        "positive": "Structural short-range forces between solid-melt interfaces: We predict the structural interaction of crystalline solid-melt interfaces\nusing amplitude equations which are derived from classical density functional\ntheory or phase-field-crystal modeling. The solid ordering decays exponentially\non the scale of the interface thickness at solid-melt interfaces; the overlap\nof two such profiles leads to a short range interaction, which is mainly\ncarried by the longest-range density waves, which can facilitate grain boundary\npremelting. We calculate the tail of these interactions, depending on the\nrelative translation of the two crystals fully analytically and predict the\ninteraction potential, and compare it to numerical simulations. For grain\nboundaries the interaction is predicted to decay twice faster as for two\ncrystals without misorientation."
    },
    {
        "anchor": "Measuring the intrinsic charge transfer gap using K-edge X-ray\n  absorption spectroscopy: Pre-edge features in X-ray absorption spectroscopy contain key information\nabout the lowest excited states and thus on the most interesting physical\nproperties of the system. In transition metal oxides they are particularly\nstructured but extracting physical parameters by comparison with a calculation\nis not easy due to several computational challenges. By combining core-hole\nattraction and correlation effects in first principles approach, we calculate\nNi K-edge X-ray absorption spectra in NiO. We obtain a striking, parameter-free\nagreement with experimental data and show that dipolar pre-edge features above\nthe correlation gap are due to non-local excitations largely unaffected by the\ncore-hole. We show that in charge transfer insulators, this property can be\nused to measure the correlation gap and probe the intrinsic position of the\nupper-Hubbard band.",
        "positive": "Do Cloaked Objects Really Scatter Less?: We discuss the global scattering response of invisibility cloaks over the\nentire frequency spectrum, from static to very high frequencies. Based on\nlinearity, causality and energy conservation we show that the total extinction\nand scattering, integrated over all wavelengths, of any linear, passive, causal\nand non-diamagnetic cloak necessarily increases compared to the uncloaked case.\nIn light of this general principle, we provide a quantitative measure to\ncompare the global performance of different cloaking techniques and we discuss\nsolutions to minimize the global scattering signature of an object using thin,\nsuperconducting shells. Our results provide important physical insights on how\ninvisibility cloaks operate and affect the global scattering of an object,\nsuggesting ways to defeat countermeasures aimed at detecting cloaked objects\nusing short impinging pulses."
    },
    {
        "anchor": "Coherent Light Control of a Metastable Hidden Phase: Metastable phases present a promising route to expand the functionality of\ncomplex materials. Of particular interest are light-induced metastable phases\nthat are inaccessible under equilibrium conditions, as they often host new,\nemergent properties switchable on ultrafast timescales. However, the processes\ngoverning the trajectories to such hidden phases remain largely unexplored.\nHere, using time- and angle-resolved photoemission spectroscopy, we investigate\nthe ultrafast dynamics of the formation of a hidden quantum state in the\nlayered dichalcogenide 1T-TaS$_2$ upon photoexcitation. Our results reveal the\nnonthermal character of the transition governed by a collective\ncharge-density-wave excitation. Utilizing a double-pulse excitation of the\nstructural mode, we show vibrational coherent control of the phase-transition\nefficiency. Our demonstration of exceptional control, switching speed, and\nstability of the hidden phase are key for device applications.",
        "positive": "Magnetism of epitaxial Tb films on W(110) studied by spin-polarized\n  low-energy electron microscopy: Thin epitaxial films of Tb metal were grown on a clean W(110) substrate in\nultra-high vacuum and studied in-situ by low-energy electron microscopy.\nAnnealed films present magnetic contrast in spin-polarized low-energy electron\nmicroscopy. The energy dependence of the electron reflectivity was determined\nand a maximum value of its spin asymmetry of about 1\\% was measured. The\nmagnetization direction of the Tb films is in-plane. Upon raising the\ntemperature, no change in the domain distribution is observed, while the\nasymmetry in the electron reflectivity decreases when approaching the critical\ntemperature, following a power law $ \\sim (1 - T/T_C)^\\beta$ with a critical\nexponent $\\beta$ of 0.39."
    },
    {
        "anchor": "Hydration Peculiarities of Graphene Oxides with Multiple Oxidation\n  Degrees: Hydration properties of graphene oxide (GO) are essential for most of its\npotential applications. In this work, we employ atomistic molecular dynamics\nsimulations to investigate seven GO compositions with different levels of\noxygenation. Two atomic charge models for GO are compared: (1) sp2 carbons are\npurely Lennard-Jones sites; (2) sp2 carbon charges are consistent with the\nCHELPG scheme. Structural properties were found to depend insignificantly on\nthe charge model, whereas thermodynamics appeared very sensitive. In\nparticular, the simplified model provides systematically stronger GO/water\ncoupling, as compared to the more accurate model. For all GO compositions,\nhydration free energies are in the range -5 to -45 kJ mol-1 indicating that\nhydration is thermodynamically favorable even for modest oxidation degrees,\nthus differing drastically from the case of pristine graphene and graphite. The\nresults and discussion presented hereby provide a physical background for\nmodern applications of GO, e.g. in electrodes of supercapacitors and inhibitors\nin processes involving biological molecules.",
        "positive": "Implicit solvation model for density-functional study of nanocrystal\n  surfaces and reaction pathways: Solid-liquid interfaces are at the heart of many modern-day technologies and\nprovide a challenge to many materials simulation methods. A realistic\nfirst-principles computational study of such systems entails the inclusion of\nsolvent effects. In this work we implement an implicit solvation model that has\na firm theoretical foundation into the widely used density-functional code\nVASP. The implicit solvation model follows the framework of joint density\nfunctional theory. We describe the framework, our algorithm and implementation,\nand benchmarks for small molecular systems. We apply the solvation model to\nstudy the surface energies of different facets of semiconducting and metallic\nnanocrystals and the S$_{\\text{N}} 2$ reaction pathway. We find that solvation\nreduces the surface energies of the nanocrystals, especially for the\nsemiconducting ones and increases the energy barrier of the S$_{\\text{N}} 2$\nreaction."
    },
    {
        "anchor": "Common origin of exotic properties in ceramic and hybrid negative\n  thermal expansion materials: Many ceramic and hybrid metal-organic framework materials show negative\nthermal expansion (NTE): they \\textit{contract} instead of expanding on heating\n\\cite{Barrera_Miller_Lind_Romao 2005}. Their structures are invariably\ncharacterised as a network of polyhedral groups of atoms that are connected\nthrough sharing of corner atoms or by shared ligands. Empirically, NTE\nmaterials tend to show pressure-induced softening, pressure enhancement of NTE,\nand the reduction of NTE on heating. But such effects have only been\ninvestigated in a small number of materials \\cite{Pantea 2006,Chapman\n2005,Chapman 2007,Fangexp 2013}, and as yet there is no general framework for\nunderstanding the whole suite of properties together. By studying models with\nHamiltonians chosen to reflect the physical picture generally accepted as\nresponsible for NTE in framework materials, we demonstrate that NTE,\npressure-enhanced NTE, and pressure-induced softening naturally emerge\ntogether. We then show how anharmonic interactions lead to structural warm\nhardening---something that has only previously been seen in laser-excited\nwarm-dense matter \\cite{Ernstorfer 2009}---as well as to the transition from\nNTE to positive thermal expansion and the disappearing of the pressure-induced\nsoftening at high temperatures.",
        "positive": "Depolarization Induced III-V Triatomic Layers with Tristable\n  Polarization States: The integration of ferroelectrics that exhibit high dielectric,\npiezoelectric, and thermal susceptibilities with the mainstream semiconductor\nindustry will enable novel device types for widespread applications, and yet\nthere are few silicon-compatible ferroelectrics suitable for device\ndownscaling. We demonstrate with first-principles calculations that the\nenhanced depolarization field at the nanoscale can be utilized to soften\nunswitchable wurtzite III-V semiconductors, resulting in ultrathin\ntwo-dimensional (2D) sheets possessing reversible polarization states. A 2D\nsheet of AlSb consisting of three atomic planes is identified to host both\nferroelectricity and antiferroelectricity, and the tristate switching is\naccompanied by a metal-semiconductor transition. The thermodynamics stability\nand potential synthesizability of the triatomic layer are corroborated with\nphonon spectrum calculations, ab initio molecular dynamics, and\nvariable-composition evolutionary structure search. We propose a 2D AlSb-based\nhomojunction field effect transistor that supports three distinct and\nnonvolatile resistance states. This new class of III-V semiconductor-derived 2D\nmaterials with dual ferroelectricity and antiferroelectricity opens up the\npossibility for nonvolatile multibit-based integrated nanoelectronics."
    },
    {
        "anchor": "First evidence of a strong Magneto-capacitance coupling at room\n  temperature in integrated piezoelectric resonators: In the vicinity of their resonance frequency, piezoelectric resonators are\nhighly sensitive to small perturbations. The present report is focussed on the\nmagnetic field as a perturbation source. First, magneto-dielectric modulation\nof more than 10% is achieved at room temperature on both ferroelectric single\ncrystals and quartz discs. Since such piezoelectric resonators are now\navailable as membranes directly integrated on Silicon wafer, we have checked\nthe magneto-dielectric modulation in such resonators. We show here for the\nfirst time that a moderate magnetic field of 2.104 Oersteds is able to\nefficiently tune the impedance of these resonators in their resonance window.",
        "positive": "Peculiarities of magnetic ordering in the S = 5/2 two-dimensional\n  square-lattice antimonate NaMnSbO4: An orthorhombic compound, NaMnSbO4, represents a square net of magnetic Mn2+\nions residing in vertex-shared oxygen octahedra. Its static and dynamic\nmagnetic properties were studied using magnetic susceptibility, specific heat,\nmagnetization, electron spin resonance (ESR), nuclear magnetic resonance (NMR)\nand density functional calculations. Thermodynamic data indicate an\nestablishment of the long-range magnetic order with TN about 44 K, which is\npreceded by a short-range one at about 55 K. In addition, a non-trivial\nwasp-waisted hysteresis loop of the magnetization was observed, indicating that\nthe ground state is most probably canted antiferromagnetic. Temperature\ndependence of the magnetic susceptibility is described reasonably well in the\nframework of 2D square lattice model with the main exchange parameter J = -5.3\nK, which is in good agreement with density functional analysis, NMR and ESR\ndata."
    },
    {
        "anchor": "The growth of metastable fcc Fe78Ni22 thin films on H-Si(100) substrates\n  suitable for focused ion beam direct magnetic patterning: We have studied the growth of metastable face-centered-cubic, non-magnetic\nFe78Ni22 thin films on silicon substrates. These films undergo a magnetic\n(paramagnetic to ferromagnetic) and structural (fcc to bcc) phase\ntransformation upon ion beam irradiation and thus can serve as a template for\ndirect writing of magnetic nanostructures by the focused ion beam. So far,\nthese films were prepared only on single crystal Cu(100) substrates. We show\nthat transformable Fe78Ni22 thin films can also be prepared on a\nhydrogen-terminated Si(100) with a 130-nm-thick Cu(100) buffer layer. The\nH-Si(100) substrates can be prepared by hydrofluoric acid etching or by\nannealing at 1200{\\deg}C followed by adsorption of atomic hydrogen. The Cu(100)\nbuffer layer and Fe78Ni22 fcc metastable thin film were deposited by thermal\nevaporation in an ultra-high vacuum. The films were consequently transformed\nin-situ by 4keV Ar+ ion irradiation and ex-situ by a 30 keV Ga+ focused ion\nbeam, and their magnetic properties were studied by magneto-optical Kerr effect\nmagnetometry. The substitution of expensive copper single crystal substrate by\nstandard silicon wafers dramatically expands application possibilities of\nmetastable paramagnetic thin films for focused ion beam direct magnetic\npatterning.",
        "positive": "Magnetic properties of restacked 2D spin $\\frac{1}{2}$ honeycomb\n  RuCl$_3$ nanosheets: Spin $\\frac{1}{2}$ honeycomb materials have gained substantial interest due\nto their exotic magnetism and possible application in quantum computing.\nHowever, in all current materials out-of-plane interactions are interfering\nwith the in-plane order, hence a true 2D magnetic honeycomb system is still of\ndemand. Here, we report the exfoliation of the magnetic semiconductor\n$\\alpha$-RuCl$_3$ into the first halide monolayers and the magnetic\ncharacterization of the spin $\\frac{1}{2}$ honeycomb arrangement of\nturbostratically stacked RuCl$_3$ monolayers. The exfoliation is based on a\nreductive lithiation/hydration approach, which gives rise to a loss of\ncooperative magnetism due to the disruption of the spin $\\frac{1}{2}$ state by\nelectron injection into the layers. After an oxidative treatment, cooperative\nmagnetism similar to the bulk is restored. The oxidized pellets of restacked\nsingle layers feature a magnetic transition at T$_N$ = 7 K in the in-plane\ndirection, while the magnetic properties in the out-of-plane direction vastly\ndiffer from bulk $\\alpha$-RuCl$_3$. The macroscopic pellets of RuCl$_3$\ntherefore behave like a stack of monolayers without any symmetry relation in\nthe stacking direction. The deliberate introduction of turbostratic disorder to\nmanipulate the spin structure of RuCl$_3$ is of interest for research in\nfrustrated magnetism and complex magnetic order as predicted by the\nKitaev-Heisenberg model."
    },
    {
        "anchor": "Mechanical Properties of La0.6Sr0.4Co0.2Fe0.8O3-d Fuel Cell Electrodes: LSCF is a promising candidate for the cathode in SOFCs. Understanding the\nmicrostructural characteristics is crucial to its application because they\npredominately determine the performance and durability of the porous cathodes\nand hence of the SOFCs. To date little work has been reported on its mechanical\nproperties and their correlation with the 3D microstructures. The main purpose\nof this research was to study the mechanical properties of both films and bulk\nsamples, and to evaluate the effect of microstructural parameters, by means of\nboth experimental and numerical methods. Room-temperature mechanical properties\nwere investigated by nanoindentation. The elastic modulus of the bulk samples\nwas found to increase from 33.8 to 174.3 GPa and hardness from 0.64 to 5.32 GPa\nas the porosity decreased from 0.45 to 0.05 after sintering at 900 to 1200C. It\nwas shown that reliable measurements of the true properties of the films were\nobtained provided that the effects from both surface roughness and substrate\nwere minimised to neglected levels within a certain range of indentation depth\nto film thickness ratio. The fracture toughnesses of bulk LSCF were determined\nto increase from 0.51 to 0.99 MPam0.5. The microstructures of films were\ncharacterised using FIB-SEM slice and view technique and the actual 3D\nmicrostructure models of the porous films were reconstructed based on the\ntomographic data obtained. Finite element modelling of the elastic modulus\nagreed well with the nanoindentation results. The 3D microstructures were\nnumerically modified at constant porosity using cellular automaton method, so\nthat the influence on elastic modulus of factors other than porosity could be\nevaluated. It was found that the heterogeneity of the pore structure has a\nsignificant influence on the elastic properties computed using mechanical\nsimulation.",
        "positive": "A Raman Probe of Phonons and Electron-phonon Interactions in NbIrTe4: The semimetal NbIrTe4 has been proposed to be a Type-II Weyl semimetal with 8\npairs of opposite Chirality Weyl nodes which are very close to the Fermi\nenergy. This topological electronic structure is made possible because of the\nbroken inversion symmetry of NbIrTe4 which is an orthorhombic crystal with Td\nsymmetry. Using micro-Raman scattering as a probe, we observe the frequencies\nand symmetries of 19 phonon modes (ranging from 40 to 260 cm-1) in this\nmaterial and compare to Density Functional Theory calculations. Using angular\nand polarization resolved Raman scattering for green (514 nm) and red (633 nm)\nlaser excitation, we show that it is possible to extract the excitation energy\ndependence of the Raman tensor elements associated with each measurable phonon\nmode. We show that these tensor elements vary substantially in a small energy\nrange which reflects a strong variation of the electron-phonon coupling for\nthese modes."
    },
    {
        "anchor": "Ferroelectricity of structural origin in spin-chain compounds\n  Ca$_3$Co$_{2-x}$Mn$_x$O$_6$: We report a systematic study of the structure, electric and magnetic\nproperties of Ca$_3$Co$_{2-x}$Mn$_x$O$_6$ single crystals with $x =$ 0.72 and\n0.26. The DC and AC magnetic susceptibilities display anomalies with\ncharacteristic of the spin freezing. The crystals show ferroelectric transition\nat 40 K and 35 K ($T_{FE}$) for $x =$ 0.72 and 0.26, respectively, with a large\nvalue of 1400 $\\mu$C/m$^2$ at 8 K for electric polarization ($P_c$) along the\nspin-chain ($c$-axis) direction. Interestingly, the electric polarization\nperpendicular to the chain direction ($P_{ab}$) can also be detected and has\nvalue of 450 and 500 $\\mu$C/m$^2$ at 8 K for the $x =$ 0.72 and 0.26 samples,\nrespectively. The specific heat and magnetic susceptibility show no anomaly\naround $T_{FE}$, which means that the electric polarization of these samples\nhas no direct relationship with the magnetism. The X-ray diffraction and the\nRaman spectroscopy indicate that these samples may undergo Jahn-Teller\ndistortions that could be the reason of electric polarization.",
        "positive": "Practical $GW$ scheme for electronic structure of 3$d$-transition-metal\n  monoxide anions: ScO$^{-}$, TiO$^{-}$, CuO$^{-}$, and ZnO$^{-}$: The $GW$ approximation to many-body perturbation theory is a reliable tool\nfor describing charged electronic excitations, and it has been successfully\napplied to a wide range of extended systems for several decades using a\nplane-wave basis. However, the $GW$ approximation has been used to test limited\nspectral properties of a limited set of finite systems (e.g. frontier orbital\nenergies of closed-shell $sp$ molecules) only for about a decade using a\nlocal-orbital basis. Here, we calculate the quasiparticle spectra of closed-\nand open-shell molecular anions with partially and completely filled 3$d$\nshells (shallow and deep 3$d$ states, respectively), ScO$^{-}$, TiO$^{-}$,\nCuO$^{-}$, and ZnO$^{-}$, using various levels of $GW$ theory, and compare them\nto experiments to evaluate the performance of the $GW$ approximation on the\nelectronic structure of small molecules containing 3$d$ transition metals. We\nfind that the $G$-only eigenvalue self-consistent $GW$ scheme with $W$ fixed to\nthe PBE level ($G_{n}W_{0}$@PBE), which gives the best compromise between\naccuracy and efficiency for solids, also gives good results for both localized\n($d$) and delocalized ($sp$) states of 3$d$-transition-metal oxide molecules.\nThe success of $G_{n}W_{0}$@PBE in predicting electronic excitations in these\nsystems reasonably well is likely due to the fortuitous cancellation effect\nbetween the overscreening of the Coulomb interaction by PBE and the\nunderscreening by the neglect of vertex corrections. Together with the absence\nof the self-consistent field convergence error (e.g. spin contamination in\nopen-shell systems) and the $GW$ multi-solution issue, the $G_{n}W_{0}$@PBE\nscheme gives the possibility to predict the electronic structure of complex\nreal systems (e.g. molecule-solid and $sp$-$d$ hybrid systems) accurately and\nefficiently."
    },
    {
        "anchor": "Electronic and optical properties of ferromagnetic GaMnAs in a\n  multi-band tight-binding approach: We consider the electronic properties of ferromagnetic bulk GaMnAs at zero\ntemperature using two realistic tight-binding models, one due to Tang and\nFlatte and one due to Masek. In particular, we study the density of states, the\nFermi energy, the inverse participation ratio, and the optical conductivity\nwith varying impurity concentration x=0.01-0.15. The results are very sensitive\nto the assumptions made for the on-site and hopping matrix elements of the Mn\nimpurities. For low concentrations, x<0.02, Masek's model shows only small\ndeviations from the case of p-doped GaAs with increased number of holes while\nwithin Tang and Flatte's model an impurity-band forms. For higher\nconcentrations x, Masek's model shows minor quantitative changes in the\nproperties we studied while the results of the Tang and Flatte model exhibit\nqualitative changes including strong localization of eigenstates with energies\nclose to the band edge. These differences between the two approaches are in\nparticular visible in the optical conductivity, where Masek's model shows a\nDrude peak at zero frequency while no such peak is observed in Tang and\nFlatte's model. Interestingly, although the two models differ qualitatively the\ncalculated effective optical masses of both models are similar within the range\nof 0.4-1.0 of the free electron mass.",
        "positive": "Facile Self-Assembly of Quantum Plasmonic Circuit Components: Efficient coupling between solid state quantum emitters and plasmonic\nwaveguides is important for the realization of integrated circuits for quantum\ninformation, communication and sensing. However, realization of plasmonic\ncircuits is still scarce, particularly due to challenges associated with\naccurate positioning of quantum emitters near plasmonic resonators. Current\npathways for the construction of plasmonic circuits involve cumbersome and\ncostly methods such as scanning atomic force microscopy or mechanical\nmanipulation, where individual elements are physically relocated using the\nscanning tip. Here, we introduce a simple, fast and cost effective chemical\nself-assembly method for the attachment of two primary components of a\npractical plasmonic circuit: a single photon emitter and a waveguide. Our\nmethod enables coupling of nanodiamonds with a single quantum emitter (the\nnitrogen-vacancy (NV) center) onto the terminal of a silver nanowire, by simply\nvarying the concentration of ascorbic acid (AA) in a reaction solution. The AA\nconcentration is used to control the extent of agglomeration, and can be\noptimised so as to cause preferential, selective activation of the tips of the\nnanowires. The nanowire-nanodiamond structures show efficient plasmonic\ncoupling of fluorescence emission from single NV centers into surface plasmon\npolariton (SPP) modes, evidenced by a more than two-fold reduction in\nfluorescence lifetime and an increase in fluorescence intensity."
    },
    {
        "anchor": "Symmetry Analysis for the Ruddlesden-Popper Systems, Ca3Mn2O7 and\n  Ca3Ti2O7: We perform a symmetry analysis of the zero-temperature instabilities of the\ntetragonal phase of Ca3Mn2O7 and Ca3Ti2O7 which is stable at high temperature.\nWe introduce order parameters to characterize each of the possible lattice\ndistortions in order to construct a Landau free energy which elucidates the\nproposed group-subgroup relations for structural transitions in these systems.\nWe include the coupling between the unstable distortion modes and the\nmacroscopic strain tensor. We also analyze the symmetry of the dominantly\nantiferromagnetic ordering which allows weak ferromagnetism. We show that in\nthis phase the weak ferromagnetic moment and the spontaneous ferroelectric\npolarization are coupled, so that rotating one of these ordering by applying an\nexternal electric or magnetic field one can rotate the other ordering. We\ndiscuss the number of different domains (including phase domains) which exist\nin each of the phases and indicate how these may be observed.",
        "positive": "Energetics and diffusion of gold in bismuth telluride: We have coupled electron microscopy and energy dispersive spectroscopy\nexperiments with \\textit{ab-initio} modeling to study the solubility and\ndiffusion of Au in Bi$_2$Te$_3$. We found that thermal annealing of Au films\nresults in Au concentrations in Bi$_2$Te$_3$ above the previously reported\nsolubility limit. The time scale of Au diffusion into Bi$_2$Te$_3$ is also much\ngreater than expected. To explain our observations, we calculate defect\nformation energies and diffusion barriers within DFT. We identify an\ninterstitial mechanism consistent with the previously observed low solubility\nand (rapid) anisotropic diffusion. However, the lower formation energies of\nsubstitutional defects suggest that they may be active in our experiments and\nexplain the high observed concentrations."
    },
    {
        "anchor": "A short note on approximating the critical strain for the onset of\n  dynamic recrystallization: This note provides a MATLAB code to determine the critical strain associated\nwith the onset of dynamic recrystallization. The code takes a closed-form\nconstitutive model and derives the critical strain by solving $\\partial^2\n\\theta / \\partial \\sigma^2 = 0$. Moreover, several models that could be used\nfor this purpose are studied.",
        "positive": "Towards Layer-Selective Quantum Spin Hall Channels in Weak Topological\n  Insulator Bi4Br2I2: Weak topological insulators, constructed by stacking quantum spin Hall\ninsulators with weak interlayer coupling, offer promising quantum electronic\napplications through topologically nontrivial edge channels. However, the\ncurrently available weak topological insulators are stacks of the same quantum\nspin Hall layer with translational symmetry in the out-of-plane direction,\nleading to the absence of the channel degree of freedom for edge states. Here,\nwe study a candidate weak topological insulator, Bi4Br2I2, which is alternately\nstacked by three different quantum spin Hall insulators, each with tunable\ntopologically non-trivial edge states. Our angle-resolved photoemission\nspectroscopy and first-principles calculations show that an energy gap opens at\nthe crossing points of different Dirac cones correlated with different layers\ndue to the interlayer interaction. This is essential to achieve the tunability\nof topological edge states as controlled by varying the chemical potential. Our\nwork offers a perspective for the construction of tunable quantized conductance\ndevices for future spintronic applications."
    },
    {
        "anchor": "Interfacial microscopic mechanism of free energy minimization in Omega\n  precipitate formation: Precipitate strengthening of light metals underpins a large segment of\nindustry.Yet, quantitative understanding of physics involved in precipitate\nformation is often lacking, especially, about interfacial contribution to the\nenergetics of precipitate formation.Here, we report an intricate strain\naccommodation and free energy minimization mechanism in the formation of Omega\nprecipitates (Al2Cu)in the Al_Cu_Mg_Ag alloy. We show that the affinity between\nAg and Mg at the interface provides the driving force for lowering the heat of\nformation, while substitution between Mg, Al and Cu of different atomic radii\nat interfacial atomic sites alters interfacial thickness and adjust precipitate\nmisfit strain. The results here highlight the importance of interfacial\nstructure in precipitate formation, and the potential of combining the power of\natomic resolution imaging with first-principles theory for unraveling the\nmystery of physics at nanoscale interfaces.",
        "positive": "Photodetection in p-n junctions formed by electrolyte-gated transistors\n  of two-dimensional crystals: Transition metal dichalcogenide (TMDC) monolayers have attracted much\nattention due to their strong light absorption and excellent electronic\nproperties. These advantages make this type of two-dimensional crystal a\npromising one for optoelectronic device applications. In the case of\nphotoelectric conversion devices such as photodetectors and photovoltaic cells,\np-n junctions are one of the most important devices. Here, we demonstrate\nphotodetection with WSe2 monolayer films. We prepare the electrolyte-gated\nambipolar transistors and electrostatic p-n junctions are formed by the\nelectrolyte-gating technique at 270 K. These p-n junctions are cooled down to\nfix the ion motion (and p-n junctions) and we observed the reasonable\nphotocurrent spectra without the external bias, indicating the formation of p-n\njunctions. Very interestingly, two-terminal devices exhibit higher\nphotoresponsivity than that of three-terminal ones, suggesting the formation of\nhighly balanced anion and cation layers. The maximum photoresponsivity reaches\n5 mA/W in resonance with the first excitonic peak. Our technique provides\nimportant evidence for optoelectronics in atomically thin crystals."
    },
    {
        "anchor": "Magneto-optical properties of Co|Pt multilayer systems: We are reporting, for the first time in the literature, theoretical Kerr\nspectra of Co|Pt multilayer systems as obtained on a first principles basis\nincluding multiple reflections and interferences from all the boundaries\nin-between the layers.",
        "positive": "Computation of the thermal conductivity using classical and quantum\n  molecular dynamics based methods: The thermal conductivity of a model for solid argon is investigated using\nnonequilibrium molecular dynamics methods, as well as the traditional Boltzmann\ntransport equation approach with input from molecular dynamics calculations,\nboth with classical and quantum thermostats. A surprising result is that, at\nlow temperatures, only the classical molecular dynamics technique is in\nagreement with the experimental data. We argue that this agreement is due to a\ncompensation of errors, and raise the issue of an appropriate method for\ncalculating thermal conductivities at low (below Debye) temperatures."
    },
    {
        "anchor": "Two-Dimensional Phononic Crystals: Disorder Matters: The design and fabrication of phononic crystals (PnCs) hold the key to\ncontrol the propagation of heat and sound at the nanoscale. However, there is a\nlack of experimental studies addressing the impact of order/disorder on the\nphononic properties of PnCs. Here, we present a comparative investigation of\nthe influence of disorder on the hypersonic and thermal properties of\ntwo-dimensional PnCs. PnCs of ordered and disordered lattices are fabricated of\ncircular holes with equal filling fractions in free-standing Si membranes.\nUltrafast pump and probe spectroscopy (asynchronous optical sampling) and Raman\nthermometry based on a novel two-laser approach are used to study the phononic\nproperties in the gigahertz (GHz) and terahertz (THz) regime, respectively.\nFinite element method simulations of the phonon dispersion relation and\nthree-dimensional displacement fields furthermore enable the unique\nidentification of the different hypersonic vibrations. The increase of surface\nroughness and the introduction of short-range disorder are shown to modify the\nphonon dispersion and phonon coherence in the hypersonic (GHz) range without\naffecting the room-temperature thermal conductivity. On the basis of these\nfindings, we suggest a criteria for predicting phonon coherence as a function\nof roughness and disorder.",
        "positive": "Large exchange bias in polycrystalline MnN/CoFe bilayers at room\n  temperature: We report on the new polycrystalline exchange bias system MnN/CoFe, which\nshows exchange bias of up to 1800Oe at room temperature with a coercive field\naround 600Oe. The room temperature values of the interfacial exchange energy\nand the effective uniaxial anisotropy are estimated to be $J_\\mathrm{eff} =\n0.41\\,\\mathrm{mJ}/\\mathrm{m}^2$ and $K_\\mathrm{eff} =\n37\\,\\mathrm{kJ}\\,/\\,\\mathrm{m}^3$. The thermal stability was found to be\ntunable by controlling the nitrogen content of the MnN. The maximum blocking\ntemperature exceeds $325^\\circ$C, however the median blocking temperature in\nthe limit of thick MnN is $160^\\circ$C. Good oxidation stability through\nself-passivation was observed, enabling the use of MnN in lithographically\ndefined microstructures. As a proof-of-principle we demonstrate a simple GMR\nstack exchange biased with MnN, which shows clear separation between parallel\nand antiparallel magnetic states. These properties come along with a\nsurprisingly simple manufacturing process for the MnN films."
    },
    {
        "anchor": "Influence of non-local exchange on RKKY interactions in III-V diluted\n  magnetic semiconductors: The RKKY interaction between substitutional Mn local moments in GaAs is both\nspin-direction-dependent and spatially anisotropic. In this Letter we address\nthe strength of these anisotropies using a semi-phenomenological tight-binding\nmodel which treats the hybridization between Mn d-orbitals and As p-orbitals\nperturbatively and accounts realistically for the non-local exchange\ninteraction between their spins. We show that exchange non-locality,\nvalence-band spin-orbit coupling, and band-structure anisotropy all play a role\nin determining the strength of both effects. We use these results to estimate\nthe degree of ground-state magnetization suppression due to frustrating\ninteractions between randomly located Mn ions.",
        "positive": "Three-Dimensional Dirac Electrons at the Fermi Energy in Cubic Inverse\n  Perovskites: Ca_3PbO and its Family: The band structure of cubic inverse perovskites, Ca_3PbO and its family, are\ninvestigated with the first-principles method. A close observation of the band\nstructure reveals that six equivalent Dirac electrons with a very small mass\nexist on the line connecting the Gamma- and X-points, and at the symmetrically\nequivalent points in the Brillouin zone. The discovered Dirac electrons are\nthree-dimensional and remarkably located exactly at the Fermi energy. A\ntight-binding model describing the low-energy band structure is also\nconstructed and used to discuss the origin of the Dirac electrons in this\nmaterial. Materials related to Ca_3PbO are also studied, and some design\nprinciples for the Dirac electrons in this series of materials are proposed."
    },
    {
        "anchor": "Lattice dynamics and magnetic exchange interactions in GeCo2O4, a spinel\n  with S = 1/2 pyrochlore lattice: GeCo$_2$O$_4$ is a unique system in the family of cobalt spinels ACo$_2$O$_4$\n(A= Sn, Ti, Ru, Mn, Al, Zn, Fe, etc.) in which magnetic Co ions stabilize on\nthe pyrochlore lattice exhibiting a large degree of orbital frustration. Due to\nthe complexity of the low-temperature antiferromagnetic (AFM) ordering and\nlong-range magnetic exchange interactions, the lattice dynamics and magnetic\nstructure of GeCo$_2$O$_4$ spinel has remained puzzling. To address this issue,\nhere we present theoretical and experimental investigations of the highly\nfrustrated magnetic structure, and the infrared (IR) and Raman-active phonon\nmodes in the spinel GeCo$_2$O$_4$, which exhibits an AFM ordering below the\nN\\'eel temperature $T_N$ ~21 K, followed by a cubic ($Fd{\\bar 3}m$) to\ntetragonal ($I4_{1}/amd$) structural phase transition at $T_S$ ~16 K. Our\ndensity-functional theory (DFT+U) calculations reveal that one needs to\nconsider magnetic-exchange interactions up to the third nearest neighbors to\nget an accurate description of the low-temperature AFM order in GeCo$_2$O$_4$.\nAt room temperature three distinct IR-active modes ($T_{1u}$) are observed at\nfrequencies 680, 413, and 325 cm$^{-1}$ along with four Raman-active modes\n$A_{1g}$, $T_{2g}(1)$, $T_{2g}(2)$, and $E_{g}$ at frequencies 760, 647, 550,\nand 308 cm$^{-1}$, respectively, which match reasonably well with our DFT+U\ncalculated values. All the IR-active and Raman-active phonon modes exhibit\nsignatures of moderate spin-phonon coupling. The temperature dependence of\nvarious parameters, such as the shift, width, and intensity, of the\nRaman-active modes, is also discussed. Noticeable changes around $T_N$ and\n$T_S$ are observed in the Raman line parameters of the $E_{g}$ and $T_{2g}$\nmodes, which are associated with the modulation of the Co-O bonds in CoO$_6$\noctahedra during the excitations of these modes.",
        "positive": "How to quantify energy landscapes of solids: We explore whether the topology of energy landscapes in chemical systems\nobeys any rules and what these rules are. To answer this and related questions\nwe use several tools: (i)Reduced energy surface and its density of states, (ii)\ndescriptor of structure called fingerprint function, which can be represented\nas a one-dimensional function or a vector in abstract multidimensional space,\n(iii) definition of a ''distance'' between two structures enabling\nquantification of energy landscapes, (iv) definition of a degree of order of a\nstructure, and (v) definitions of the quasi-entropy quantifying structural\ndiversity. Our approach can be used for rationalizing large databases of\ncrystal structures and for tuning computational algorithms for structure\nprediction. It enables quantitative and intuitive representations of energy\nlandscapes and reappraisal of some of the traditional chemical notions and\nrules. Our analysis confirms the expectations that low-energy minima are\nclustered in compact regions of configuration space (\"funnels\") and that\nchemical systems tend to have very few funnels, sometimes only one. This\nanalysis can be applied to the physical properties of solids, opening new ways\nof discovering structure-property relations. We quantitatively demonstrate that\ncrystals tend to adopt one of the few simplest structures consistent with their\nchemistry, providing a thermodynamic justification of Pauling's fifth rule."
    },
    {
        "anchor": "Advanced Cd1-xMnxTe:Fe2+ semiconductor crystals with linear sin-band\n  redshift of absorption and emission spectra: Doped semiconductor crystals of solid solution $Cd_{1-x}Mn_{x}Te:Fe^{2+}$\nwere grown by the high-pressure Bridgman method covering the range of its\nexistence as a zinc blende crystal structure. The concentration of\nFe-impurities was approximately 0.001 wt.% in all studied samples. The\ncorrelations between the composition of solid solution crystals of\n$Cd_{1-x}Mn_{x}Te:Fe^{2+}$, band gap, lattice period and the maxima positions\nof the $Fe^{2+}$ active ion absorption and emission spectra were found. A new\ntheoretical model based on the principle of additivity for solid solution\nsemiconductor materials has been used for explaining the long-wavelength\n''redshift'' of absorption and luminescence bands in the spectra of\n$Cd_{1-x}Mn_{x}Te:Fe^{2+}$ crystals with increasing solid solution\nconcentration. The obtained results can be used to predict the lasing range for\n$Cd_{1-x}Mn_{x}Te:Fe^{2+}$ crystal media (in all possible $Mn$ concentrations),\nwhich is potentially the longest wavelength active material for mid-IR lasing.",
        "positive": "The wave model of martensite growth for the FCC-BCC transformation of\n  iron-based alloys: This book is the first monograph in the scientific literature, dedicated to\nthe FCC-BCC transformation in iron-based alloys, in which the dynamical\napproach is used for the explanation of the martensite growth stage.\n  The rapid growth of a cooling martensite crystal is considered as a\nself-organized process controlled by the quasi-longitudinal lattice\ndisplacement waves (DW). The regime of the DW initial excitation is rigid. DW\nhave the frequencies ~$10^{10} sec^{-1}$ from the hypersound band and the\namplitudes providing the level of deformation ~$10^{-3}$. The conditions that\nare necessary for the generation of DW by non-equilibrium d-electrons are\nanalyzed.\n  A wide range of questions (from peculiarities of the electronic spectrum to\nmacroscopic morphological indicators), connected with the physical\ninterpretation of the FCC-BCC martensitic transformation in iron-based alloys,\nis discussed.\n  The short review of results having fundamental meaning for the creation of a\nphysical model describing the martensite nucleation process is given in the\nmonograph's conclusion. It is shown, that processes of the heterogeneous\nnucleation and wave growth have the genetic connection to the FCC-BCC\nmartensitic transformation. The short review of the last author's results\nrevealing features of the physical mechanisms controlling processes of\nmartensite crystal formation for all alternatives of the FCC-BCC martensitic\ntransformation is given in the monograph's epilogue."
    },
    {
        "anchor": "Ab initio Simulations of Superionic H2O, H2O2, and H9O4 Compounds: Using density functional molecular dynamics simulations, we study the\nbehavior of different hydrogen-oxygen compounds at megabar pressures and\nseveral thousands of degrees Kelvin where water has been predicted to occur in\nsuperionic form. When we study the close packed hcp and dhcp structures of\nsuperionic water, we find that they have comparable Gibbs free energies to the\nfcc structure that we predicted previously [Phys. Rev. Lett., 110 (2013)\n151102]. Then we present a comprehensive comparison of different superionic\nwater candidate structures with P2_1, P2_1/c, P3_121, Pcca, C2/m, and Pa3\nsymmetry that are based on published ground-state structures. We find that the\nP2_1 and P2_1/c structures transform into a different superionic structure with\nP2_1/c symmetry, which at 4000 K has a lower Gibbs free energy than fcc for\npressures higher than 22.8 +- 0.5 Mbar. This novel structure may also be\nobtained by distorting a hcp supercell. Finally we show that H2O2 and H9O4\nstructures will also assume a superionic state at elevated temperatures. Based\non Gibbs free energy calculations at 5000 K, we predict that superionic water\ndecompose into H2O2 and H9O4 at 68.7 +- 0.5 Mbar.",
        "positive": "Ab initio study on the electromechanical response of Janus transition\n  metal dihalide nanotubes: We study the electronic response of Janus transition metal dihalide (TMH)\nnanotubes to mechanical deformations using Kohn-Sham density functional theory.\nSpecifically, considering twelve armchair and zigzag Janus TMH nanotubes that\nare expected to be stable from the phonon analysis of flat monolayer\ncounterparts, we first compute their equilibrium diameters and then determine\nthe variation in bandgap and effective mass of charge carriers with the\napplication of tensile and torsional deformations. We find that the nanotubes\nundergo a linear and quadratic decrease in bandgap with tensile and shear\nstrain, respectively. In addition, there is a continual increase and decrease\nin the effective mass of electrons and holes, respectively. We show that for a\ngiven strain, the change in bandgap for the armchair nanotubes can be\ncorrelated with the transition metal's in-plane $d$ orbital's contribution to\nthe projected density of states at the bottom of the conduction band."
    },
    {
        "anchor": "Ferroelectric properties of RbNbO3 and RbTaO3: Phonon spectra of cubic rubidium niobate and rubidium tantalate with the\nperovskite structure are calculated from first principles within the density\nfunctional theory. Based on the analysis of unstable modes in the phonon\nspectra, the structures of possible distorted phases are determined, their\nenergies are calculated, and it is shown that $R3m$ is the ground-state\nstructure of RbNbO3. In RbTaO3, the ferroelectric instability is suppressed by\nzero-point lattice vibrations. For ferroelectric phases of RbNbO3, spontaneous\npolarization, piezoelectric, nonlinear optical, electro-optical, and other\nproperties as well as the energy band gap in the LDA and GW approximations are\ncalculated. The properties of the rhombohedral RbNbO3 are compared with those\nof rhombohedral KNbO3, LiNbO3, and BaTiO3.",
        "positive": "Scanning Tunneling Microscopy of Defect States in the Semiconductor\n  Bi$_2$Se$_3$: Scanning tunneling spectroscopy images of Bi$_2$Se$_3$ doped with excess Bi\nreveal electronic defect states with a striking shape resembling clover leaves.\nWith a simple tight-binding model we show that the geometry of the defect\nstates in Bi$_2$Se$_3$ can be directly related to the position of the\noriginating impurities. Only the Bi defects at the Se sites five atomic layers\nbelow the surface are experimentally observed. We show that this effect can be\nexplained by the interplay of defect and surface electronic structure."
    },
    {
        "anchor": "Prediction of a Heusler alloy with switchable metal-to-half-metal\n  behavior: We propose a ferromagnetic Heusler alloy that can switch between a metal and\na half-metal. Thiseffect can provide tunable spintronics properties. Using the\ndensity functional theory (DFT) withreliable implementations of the electron\ncorrelation effects, we find Mn2ScSi total energy curvesconsisting of distinct\nbranches with a very small energy difference. The phase at low lattice\ncrystalvolume is a low magnetic half-metallic state while the phase at high\nlattice crystal volume is a highmagnetic metallic state. We suggest that the\ntransition between half-metallic and metallic statescan be triggered by a\ntriaxial contraction/expansion of the crystal lattice or by an external\nmagneticfield if we assume that the lattice is cubic and remains cubic under\nexpansion/contraction. However,the phase at high volume can also undergo an\naustenite-martensite phase transition because of thepresence of Jahn-Teller\nactive3delectrons on the Mn atoms.",
        "positive": "Effect of lattice mismatch-induced strains on coupled diffusive and\n  displacive phase transformations: Materials which can undergo slow diffusive transformations as well as fast\ndisplacive transformations are studied using the phase-field method. The model\ncaptures the essential features of the time-temperature-transformation (TTT)\ndiagrams, continuous cooling transformation (CCT) diagrams, and microstructure\nformation of these alloys. In some materials systems there can exist an\nintrinsic volume change associated with these transformations. We show that\nthese coherency strains can stabilize mixed microstructures (such as retained\naustenite-martensite and pearlite-martensite mixtures) by an interplay between\ndiffusive and displacive mechanisms, which can alter TTT and CCT diagrams.\nDepending on the conditions there can be competitive or cooperative nucleation\nof the two kinds of phases. The model also shows that small differences in\nvolume changes can have noticeable effects on the early stages of martensite\nformation and on the resulting microstructures.\n  -- Long version of cond-mat/0605577\n  -- Keywords: Ginzburg-Landau, martensite, pearlite, spinodal decomposition,\nshape memory, microstructures, TTT diagram, CCT diagram, elastic compatibility"
    },
    {
        "anchor": "Symmetry Conditions for Non-reciprocal Light Propagation in Magnetic\n  Crystals: Recent studies demonstrated the violation of reciprocity in optical processes\nin low-symmetry magnetic crystals. In these crystals the speed of light can be\ndifferent for counter-propagating beams. Correspondingly, they can show strong\ndirectional anisotropies such as direction dependent absorption also called\ndirectional dichroism[S. Bord\\'acs et al., Nat. Phys. 8, 734 (2012); M. Saito\net al., J. Phys. Soc. Jpn. 77, 013705 (2008)]. Based on symmetry\nconsiderations, we identify the magnetic point groups of materials which can\nhost such directional anisotropies and also provide a list of possible\ncandidate materials to observe these phenomena. In most of these cases, the\nsymmetry of the crystal allows directional anisotropy not only for optical\nprocesses but also for the propagation of beams of particles and scalar waves.\nWe also predict new types of directional optical anisotropies -- besides the\noptical magnetoelectric effect and the magnetochiral dichroism investigated so\nfar -- and specify the magnetic point groups of crystals where they can emerge.",
        "positive": "Single crystals of DPPH grown from diethyl ether and carbon disulfide\n  solutions - Crystal structures, IR, EPR and magnetization studies: Single crystals of the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH)\nobtained from diethyl ether (ether) and carbon disulfide (CS2) were\ncharacterized by the X-ray diffraction, IR, EPR and SQUID magnetization\ntechniques. The X-ray structural analysis and IR spectra showed that the DPPH\nform crystallized from ether (DPPH1) is solvent free, whereas that one obtained\nfrom CS2 (DPPH2) is a solvate of the composition 4DPPH.CS2. Principal values of\nthe g-tensor were estimated by the X-band EPR spectroscopy at room and low (10\nK) temperatures. Magnetization studies revealed the presence of\nantiferromagnetically coupled dimers in both types of crystals. However, the\nway of dimerization as well as the strength of exchange couplings are different\nin the two DPPH samples, which is in accord with their crystal structures. The\nobtained results improved parameters accuracy and enabled better understanding\nof properties of DPPH as a standard sample in the EPR spectrometry."
    },
    {
        "anchor": "Tunable electronic properties of partially edge-hydrogenated armchair\n  boron-nitrogen-carbon nanoribbons: We employ first-principles calculations based density-functional-theory (DFT)\napproach to study electronic properties of partially and fully\nedge-hydrogenated armchair boron-nitrogen-carbon (BNC) nanoribbons (ABNCNRs),\nwith widths between 0.85 nm to 2.3 nm. Due to the partial passivation of edges,\nelectrons which do not participate in the bonding, form new energy states\nlocated near the Fermi-level. Because of these additional bands, some ABNCNRs\nexhibit metallic behavior, which is quite uncommon in armchair nanoribbons. Our\ncalculations reveal that the metallic behavior is observed for the following\npassivation patterns: (i) when B atom from one edge, and N atom from another\nedge, are unpassivated. (ii) when N atoms from both the edges are unpassivated.\n(iii) when C atom from one edge, and N atom from another edge, are\nunpassivated. Furthermore, spin-polarization is also observed for certain\npassivation schemes, which is also quite uncommon for armchair nanoribbons.\nThus, our results suggest that ABNCNRs exhibit a wide range of electronic and\n{magnetic }properties in that the fully edge-hydrogenated ABNCNRs are direct\nband gap semiconductors, while partially edge-hydrogenated ones are either\nsemiconducting, or metallic, while simultaneously exhibiting spin polarization,\nbased on the nature of passivation. We also find that the ribbons with larger\nwidths are more stable, as compared to the narrower ones.",
        "positive": "New Approach to Density Functional Theory and Description of Spectra of\n  Finite Electron Systems: The self consistent version of the density functional theory is presented,\nwhich allows to calculate the ground state and dynamic properties of finite\nmulti-electron systems. An exact functional equation for the effective\ninteraction, from which one can construct the action functional, density\nfunctional, the response functions, and excitation spectra of the considered\nsystems, is outlined. In the context of the density functional theory we\nconsider the single particle excitation spectra of electron systems and relate\nthe single particle spectrum to the eigenvalues of the corresponding Kohn-Sham\nequations. We find that the single particle spectrum coincides neither with the\neigenvalues of the Kohn-Sham equations nor with those of the Hartree-Fock\nequations."
    },
    {
        "anchor": "Phase diagram of the B-B2O3 system at pressures to 24 GPa: The evolution of topology of the B-B2O3 phase diagram has been studied at\npressures up to 24 GPa using models of phenomenological thermodynamics with\ninteraction parameters derived from experimental data on phase equilibria at\nhigh pressures and high temperatures.",
        "positive": "The Reconstruction of Pt(111) and Domain Patterns on Close-packed Metal\n  Surfaces: We have studied the reconstruction of Pt(111) theoretically using a\ntwo-dimensional Frenkel-Kontorova model for which all parameters have been\nobtained from ab initio calculations. We find that the unreconstructed surface\nlies right at the stability boundary, and thus it is relatively easy to induce\nthe surface to reconstruct into a pattern of FCC and HCP domains, as has been\nshown experimentally. The top layer is very slightly rotated relative to the\nsubstrate, resulting in the formation of \"rotors\" at intersections of domain\nwalls. The size and shape of domains is very sensitive to the density in the\ntop layer, the chemical potential, and the angle of rotation, with a smooth and\ncontinuous transition from the honeycomb pattern to a Moire pattern, via\ninterlocking triangles and bright stars. Our results show clearly that the\ndomain patterns found on several close-packed metal surfaces are related and\ntopologically equivalent."
    },
    {
        "anchor": "Ultrafast Magnetoelastic Probing of Surface Acoustic Transients: We generate in-plane magnetoelastic waves in nickel films using the\nall-optical transient grating technique. When performed on amorphous glass\nsubstrates, two dominant magnetoelastic excitations can be resonantly driven by\nthe underlying elastic distortions, the Rayleigh Surface Acoustic Wave and the\nSurface Skimming Longitudinal Wave. An applied field, oriented in the sample\nplane, selectively tunes the coupling between magnetic precession and one of\nthe elastic waves, thus demonstrating selective excitation of coexisting, large\namplitude magnetoelastic waves. Analytical calculations based on the Green's\nfunction approach corroborate the generation of the non-equilibrium surface\nacoustic transients.",
        "positive": "Piezoelectric Response and Free Energy Instability in the Perovskite\n  Crystals BaTiO3, PbTiO3 and Pb(Zr,Ti)O3: The question of the origin of the piezoelectric properties enhancement in\nperovskite ferroelectrics is approached by analyzing the Gibbs free energy of\ntetragonal BaTiO3, PbTiO3 and Pb(Zr,Ti)O3 in the framework of the\nLandau-Ginzburg-Devonshire theory. The flattening of the Gibbs free energy\nprofile appears as a fundamental thermodynamic process behind the piezoelectric\nenhancement. The generality of the approach is demonstrated by examining the\nfree energy flattening and piezoelectric enhancement as a function of\ncomposition, temperature, electric field and mechanical stress. It is shown\nthat the anisotropy of the free energy flattening is the origin of the\nanisotropic enhancement of the piezoelectric response, which can occur either\nby polarization rotation or by polarization contraction. Giant enhancement of\nthe longitudinal piezoelectric response (on the order of 1000 pC/N) is\npredicted in PbTiO3 under uniaxial compression."
    },
    {
        "anchor": "Arc-tunable Weyl Fermion metallic state in Mo$_x$W$_{1-x}$Te$_2$: Weyl semimetals may open a new era in condensed matter physics because they\nprovide the first example of Weyl fermions, realize a new topological\nclassification even though the system is gapless, exhibit Fermi arc surface\nstates and demonstrate the chiral anomaly and other exotic quantum phenomena.\nSo far, the only known Weyl semimetals are the TaAs class of materials. Here,\nwe propose the existence of a tunable Weyl metallic state in\nMo$_x$W$_{1-x}$Te$_2$ via our first-principles calculations. We demonstrate\nthat a 2% Mo doping is sufficient to stabilize the Weyl metal state not only at\nlow temperatures but also at room temperatures. We show that, within a moderate\ndoping regime, the momentum space distance between the Weyl nodes and hence the\nlength of the Fermi arcs can be continuously tuned from zero to ~ 3% of the\nBrillouin zone size via changing Mo concentration, thus increasing the\ntopological strength of the system. Our results provide an experimentally\nfeasible route to realizing Weyl physics in the layered compound\nMo$_x$W$_{1-x}$Te$_2$, where non-saturating magneto-resistance and pressure\ndriven superconductivity have been observed.",
        "positive": "Role of Kohn-Sham Kinetic Energy Density in Designing Asymptotically\n  Correct Semilocal Exchange-Correlation Functionals in Two Dimensions: The positive definite Kohn-Sham kinetic energy(KS-KE) density plays crucial\nrole in designing semilocal meta generalized gradient approximations(meta-GGAs)\nfor low dimensional quantum systems. It has been rigorously shown that near\nnucleus and at the asymptotic region, the KE-KS differ from its von\nWeizs\\\"{a}cker(VW) counterpart as contributions from different orbitals (i.e.,\ns and p orbitals) play important role. This has been explored using two\ndimensional isotropic quantum harmonic oscillator as a test case. Several\nmeta-GGA ingredients with different physical behaviors are also constructed and\nfurther used to design an accurate semilocal functionals at meta-GGA level. In\nthe asymptotic region, a new exchange energy functional is constructed using\nthe meta-GGA ingredients with formally exact properties of the enhancement\nfactor. Also, it has been shown that exact asymptotic behavior of the exchange\nenergy density and potential can be attained by choosing accurately the\nenhancement factor as a functional of meta-GGA ingredients."
    },
    {
        "anchor": "Current-limiting challenges for all-spin logic devices: All-spin logic device (ASLD) has attracted increasing interests as one of the\nmost promising post-CMOS device candidates, thanks to its low power,\nnon-volatility and logic-in-memory structure. Here we investigate the key\ncurrent-limiting factors and develop a physics-based model of ASLD through\nnano-magnet switching, the spin transport properties and the breakdown\ncharacteristic of channel. First, ASLD with perpendicular magnetic anisotropy\n(PMA) nano-magnet is proposed to reduce the critical current (Ic0). Most\nimportant, the spin transport efficiency can be enhanced by analyzing the\ndevice structure, dimension, contact resistance as well as material parameters.\nFurthermore, breakdown current density (JBR) of spin channel is studied for the\nupper current limitation. As a result, we can deduce current-limiting\nconditions and estimate energy dissipation. Based on the model, we demonstrate\nASLD with different structures and channel materials (graphene and copper).\nAsymmetric structure is found to be the optimal option for current limitations.\nCopper channel outperforms graphene in term of energy but seriously suffers\nfrom breakdown current limit. By exploring the current limit and performance\ntradeoffs, the optimization of ASLD is also discussed. This benchmarking model\nof ASLD opens up new prospects for design and implementation of future\nspintronics applications.",
        "positive": "Disconnection-Mediated Migration of Interfaces in Microstructures: I.\n  continuum model: A long-standing goal of materials science is to understand, predict and\ncontrol the evolution of microstructures in crystalline materials. Most\nmicrostructure evolution is controlled by interface motion; hence, the\nestablishment of rigorous interface equations of motion is a universal goal of\nmaterials science. We present a new model for the motion of arbitrarily curved\ninterfaces that respects the underlying crystallography of the two\nphases/domains meeting at the interface and is consistent with microscopic\nmechanisms of interface motion; i.e., disconnection migration (line defects in\nthe interface with step and dislocation character). We derive the equation of\nmotion for interface migration under the influence of a wide range of driving\nforces. In Part II of this paper [Salvalaglio, Han and Srolovitz, 2021], we\nimplement the interface model and the equation of motion proposed in this paper\nin a diffuse interface simulation approach for complex morphology and\nmicrostructure evolution."
    },
    {
        "anchor": "Spectral descriptors for bulk metallic glasses based on the\n  thermodynamics of competing crystalline phases: Metallic glasses have attracted considerable interest in recent years due to\ntheir unique combination of superb properties and processability. Predicting\nbulk metallic glass formers from known parameters remains a challenge and the\nsearch for new systems is still performed by trial and error. It has been\nspeculated that some sort of \"confusion\" during crystallization of the\ncrystalline phases competing with glass formation could play a key role. Here,\nwe propose a heuristic descriptor quantifying confusion and demonstrate its\nvalidity by detailed experiments on two well-known glass forming alloy systems.\nWith the insight provided by these results, we develop a robust model for\npredicting glass formation ability based on the spectral decomposition of\ngeometrical and energetic features of crystalline phases calculated ab-initio\nin the AFLOW high throughput framework. Our findings indicate that the\nformation of metallic glass phases could be a much more common phenomenon than\ncurrently estimated, with more than 17% of binary alloy systems being potential\nglass formers. Our approach is capable of pinpointing favorable compositions,\novercoming a major bottleneck hindering the discovery of new materials. Hence,\nit is demonstrated that smart descriptors, based solely on the energetics and\nstructure of competing crystalline phases calculated from first-principles and\navailable in online databases, others the sought-after key for accelerated\ndiscovery of novel metallic glasses.",
        "positive": "Vibrational signatures of diamondoid dimers with large intramolecular\n  London dispersion interactions: We analyze the vibrational properties of diamondoid compounds via Raman\nspectroscopy. The compounds are interconnected with carbon-carbon single bonds\nthat exhibit exceptionally large bond lengths up to 1.71 A. Attractive\ndispersion interactions caused by well-aligned intramolecular H--H contact\nsurfaces determine the overall structures of the diamondoid derivatives. The\nstrong van-der-Waals interactions alter the vibrational properties of the\ncompounds in comparison to pristine diamondoids. Supported by\ndispersion-corrected density functional theory (DFT) computations, we analyze\nand explain their experimental Raman spectra with respect to unfunctionalized\ndiamondoids. We find a new set of dispersion-induced vibrational modes\ncomprising characteristic CH/CH$_{2}$ vibrations with exceptionally high\nenergies. Further, we find structure-induced dimer modes that are indicative of\nthe size of the dimers."
    },
    {
        "anchor": "Vortex and gap generation in gauge models of graphene: Effective quantum field theoretical continuum models for graphene are\ninvestigated. The models include a complex scalar field and a vector gauge\nfield. Different gauge theories are considered and their gap patterns for the\nscalar, vector, and fermion excitations are investigated. Different gauge\ngroups lead to different relations between the gaps, which can be used to\nexperimentally distinguish the gauge theories. In this class of models the\nfermionic gap is a dynamic quantity. The finite-energy vortex solutions of the\ngauge models have the flux of the \"magnetic field\" quantized, making the\nBohm-Aharonov effect active even when external electromagnetic fields are\nabsent. The flux comes proportional to the scalar field angular momentum\nquantum number. The zero modes of the Dirac equation show that the gauge models\nconsidered here are compatible with fractionalization.",
        "positive": "Multiple exciton generation and giant external quantum efficiency in\n  VO$_2$: Multiple exciton generation (MEG) is a widely studied phenomenon in\nsemiconductor nanocrystals and quantum dots wherein photo-excited carriers\nrelax by generating additional electron-hole pairs. Here, we present the first\nexperimental observation of MEG and the same leading to giant external quantum\nefficiency (EQE) in VO$_2$, a prototype strongly correlated material. By\nemploying a photoexcitation (lamda ~ 488 nm) of ~ 4.2 times the bandgap, EQE in\nVO$_2$ is enhanced up to ~ 170 % at room temperature. Temperature dependent\nexperiments exhibit the direct relation between MEG and strength of electron\ncorrelation and suggest that such a phenomenon could be exploited in large\nnumber of strongly correlated materials for high performance solar cell\nresearch in near future."
    },
    {
        "anchor": "Mechanism of the fcc-hcp Phase Transformation in Solid Ar: We present an atomistic description of the {\\it fcc}--to--{\\it hcp}\ntransformation mechanism in solid argon (Ar) obtained from transition path\nsampling molecular dynamics simulation. The phase transition pathways collected\nduring the sampling for an 8000--particle system reveal three transition types\naccording to the lattice deformation and relaxation details. In all three\ntransition types, we see a critical accumulation of defects and uniform growth\nof a less ordered transition state, followed by a homogeneous growth of an\nordered phase. Stacking disorder is discussed to describe the transition\nprocess and the cooperative motions of atoms in \\{111\\} planes. We investigate\nthe nucleation with larger system. In a system of 18000--particles, the\ncollective movements of atoms required for this transition are facilitated by\nthe formation and growth of stacking faults. However the enthalpy barrier is\nstill far beyond the thermal fluctuation. The high barrier explains previous\nexperimental observations of the inaccessibility of the bulk transition at low\npressure and its sluggishness even at extremely high pressure. The transition\nmechanism in bulk Ar is different from Ar nanoclusters as the orthorhombic\nintermediate structure proposed for the latter is not observed in any of our\nsimulations.",
        "positive": "Subsurface Characteristics of Metal-Halide Perovskites Polished by Argon\n  Ion Beam: Focused ion beam (FIB) techniques have been frequently used to section\nmetal-halide perovskites for microstructural investigations. However, the ion\nbeams directly irradiated to the sample surface may alter the properties far\ndifferent from pristine, potentially leading to modified deterioration\nmechanisms under aging stressors. Here, we combine complementary approaches to\nmeasure the subsurface characteristics of polished perovskite and identify the\nchemical species responsible for the measured properties. Analysis of the\nexperimental results in conjunction with Monte Carlo simulations indicates that\natomic displacements and local heating occur in the subsurface of\nmethylammonium lead iodide (MAPbI3) by glazing Ar+ beam irradiation (15 nm by 4\nkV at 3 degree). The lead-rich, iodine-deficient surface promotes rapid phase\nsegregation under thermal aging conditions. On the other hand, despite the\nsubsurface modification, our experiments confirm the rest of the MAPbI3 bulk\nretains the material integrity. Our observation supports that polished\nperovskites could serve in studying the properties of bulk or buried junctions\nfar away from the altered subsurface with care."
    },
    {
        "anchor": "Second-harmonic imaging microscopy for time-resolved investigations of\n  transition metal dichalcogenides: Two-dimensional transition metal dichalcogenides (TMDC) have shown promise\nfor various applications in optoelectronics and so-called valleytronics. Their\noperation and performance strongly depend on the stacking of individual layers.\nHere, optical second-harmonic generation (SHG) in imaging mode is shown to be a\nversatile tool for systematic time-resolved investigations of TMDC monolayers\nand heterostructures in consideration of the material's structure. Large sample\nareas can be probed without the need of any mapping or scanning. By means of\npolarization dependent measurements, the crystalline orientation of monolayers\nor the stacking angles of heterostructures can be evaluated for the whole field\nof view. Pump-probe experiments then allow to correlate observed transient\nchanges of the second-harmonic response with the underlying structure. The\ncorresponding time-resolution is virtually limited by the pulse duration of the\nused laser. As an example, polarization dependent and time-resolved\nmeasurements on mono- and multilayer MoS$_2$ flakes grown on a SiO$_2$/Si(001)\nsubstrate are presented.",
        "positive": "Computational Design of Alloy Nanostructures for Optical Sensing of\n  Hydrogen: Pd nanoalloys show great potential as hysteresis-free, reliable hydrogen\nsensors. Here, a multi-scale modeling approach is employed to determine optimal\nconditions for optical hydrogen sensing using the Pd-Au-H system. Changes in\nhydrogen pressure translate to changes in hydrogen content and eventually the\noptical spectrum. At the single particle level, the shift of the plasmon peak\nposition with hydrogen concentration (i.e., the \"optical\" sensitivity) is\napproximately constant at 180 nm/c_H for nanodisk diameters >~ 100 nm. For\nsmaller particles, the optical sensitivity is negative and increases with\ndecreasing diameter, due to the emergence of a second peak originating from\ncoupling between a localized surface plasmon and interband transitions. In\naddition to tracking peak position, the onset of extinction as well as\nextinction at fixed wavelengths is considered. We carefully compare the\nsimulation results with experimental data and assess the potential sources for\ndiscrepancies. Invariably, the results suggest that there is an upper bound for\nthe optical sensitivity that cannot be overcome by engineering composition\nand/or geometry. While the alloy composition has a limited impact on optical\nsensitivity, it can strongly affect H uptake and consequently the\n\"thermodynamic\" sensitivity and the detection limit. Here, it is shown how the\nlatter can be improved by compositional engineering and even substantially\nenhanced via the formation of an ordered phase that can be synthesized at\nhigher hydrogen partial pressures."
    },
    {
        "anchor": "Effect of pore-size disorder on the electronic properties of\n  semiconducting graphene nanomeshes: Graphene nanomeshes (GNMs) are novel materials that recently raised a lot of\ninterest. They are fabricated by forming a lattice of pores in graphene.\nDepending on the pore size and pore lattice constant, GNMs can be either\nsemimetallic or semiconducting with a gap large enough (0.5 eV) to be\nconsidered for transistor applications. The fabrication process is bound to\nproduce some structural disorder due to variations in pore sizes. Recent\nelectronic transport measurements in GNM devices (ACS Appl. Mater. Interfaces\n10, 10362, 2018) show a degradation of their bandgap in devices having\npore-size disorder. It is therefore important to understand the effect of such\nvariability on the electronic properties of semiconducting GNMs. In this work\nwe use the density functional-based tight binding formalism to calculate the\nelectronic properties of GNM structures with different pore sizes, pore\ndensities, and with hydrogen and oxygen pore edge passivations. We find that\nstructural disorder reduces the electronic gap and the carrier group velocity,\nwhich may interpret recent transport measurements in GNM devices. Furthermore\nthe trend of the bandgap with structural disorder is not significantly affected\nby the change in pore edge passivation. Our results show that even with\nstructural disorder, GNMs are still attractive from a transistor device\nperspective.",
        "positive": "Spin memory of the topological material under strong disorder: Robustness to disorder - the defining property of any topological state - has\nbeen mostly tested in low-disorder translationally-invariant materials systems\nwhere the protecting underlying symmetry, such as time reversal, is preserved.\nThe ultimate disorder limits to topological protection are still unknown,\nhowever, a number of theories predict that even in the amorphous state a\nquantized conductance might yet reemerge. Here we report a directly detected\nrobust spin response in structurally disordered thin films of the topological\nmaterial Sb2Te3 free of extrinsic magnetic dopants, which we controllably tune\nfrom a strong (amorphous) to a weak crystalline) disorder state. The magnetic\nsignal onsets at a surprisingly high temperature (~ 200 K) and eventually\nceases within the crystalline state. We demonstrate that in a strongly\ndisordered state disorder-induced spin correlations dominate the transport of\ncharge - they engender a spin memory phenomenon, generated by the\nnonequilibrium charge currents controlled by localized spins. The negative\nmagnetoresistance (MR) in the extensive spin-memory phase space is isotropic.\nWithin the crystalline state, it transitions into a positive MR corresponding\nto the weak antilocalization (WAL) quantum interference effect, with a 2D\nscaling characteristic of the topological state. Our findings demonstrate that\nthese nonequilibrium currents set a disorder threshold to the topological\nstate; they lay out a path to tunable spin-dependent charge transport and point\nto new possibilities of spin control by disorder engineering of topological\nmaterials"
    },
    {
        "anchor": "Stanene: Atomically Thick Free-standing Layer of 2D Hexagonal Tin: Two dimensional (2D) layered materials have recently gained renewed interest\ndue to their exotic electronic properties along with high specific surface\narea. The prospects of exploiting these properties in sensing, catalysis,\nenergy storage, protective coatings and electrochromism have witnessed a\nparadigm shift towards the exploration of these sophisticated 2D materials. The\nexemplary performance of graphene (1) which is among the first of these\nelemental 2D materials have initiated a runaway effect in the pursuit of\nstudying alternative 2D materials. Even though graphene has tunable exotic\nelectronic properties (2), the spin-orbit (SO) coupling is weak (3) limiting\nits applications as spin filters, topological insulators etc. Topological\ninsulators by their very nature force the electrons to travel on the surface at\nvery high speeds thereby finding useful applications in electronic and photonic\ndevices. Exploration of group IV elements using first principles calculations\nhave revealed that the SO coupling increases as the atomic weight of the basis\natoms in the honeycomb lattice (4). Tin is one of the heaviest elements in this\nseries having strong spin-orbit coupling making it a promising applicant for\nroom temperature topological insulator. Thus there is an urgent need to\ndiscover novel 2D materials in the post graphene age to overcome its\ndeficiencies. We have synthesized and investigated the optical transitions in\n2D material referred to as few-layer stanene (FLS). These are analogous to\nfew-layer graphene and can be visualized by replacing carbon atoms by tin on a\ngraphene lattice. We have been able to synthesize from mono to few atomic\nlayers of free standing stanene and characterize them optically using UV-Vis\nabsorption, Raman and photoluminescence spectroscopy. First principles\ncalculations have been performed to interpret experimental results.",
        "positive": "Vacancies and dopants in two-dimensional tin monoxide: An ab initio\n  study: Layered tin monoxide (SnO) offers an exciting two-dimensional (2D)\nsemiconducting system with great technological potential for next-generation\nelectronics and photocatalytic applications. Using a combination of\nfirst-principles simulations and strain field analysis, this study investigates\nthe structural dynamics of oxygen (O) vacancies in monolayer SnO and their\nfunctionalization by complementary lightweight dopants, namely C, Si, N, P, S,\nF, Cl, H and H$_{2}$. Our results show that O vacancies are the dominant native\ndefect under Sn-rich growth conditions with active diffusion characteristics\nthat are comparable to that of graphene vacancies. Depending on the choice of\nsubstitutional species and its concentration within the material, significant\nopportunities are revealed in the doped-SnO system for facilitating\n$n$/$p$-type tendencies, work function reduction, and metallization of the\nmonolayer. N and F dopants are found to demonstrate superior mechanical\ncompatibility with the host lattice, with F being especially likely to take\npart in substitution and lead to degenerately doped phases with high open-air\nstability. The findings reported here suggest that post-growth filling of O\nvacancies in Sn-rich conditions presents a viable channel for doping 2D tin\nmonoxide, opening up new avenues in harnessing defect-engineered SnO\nnanostructures for emergent technologies."
    },
    {
        "anchor": "Enhancement of intrinsic magnetic damping in defect-free epitaxial Fe3O4\n  thin films: We have investigated the magnetic damping of precessional spin dynamics in\ndefect-controlled epitaxial grown Fe$_3$O$_4$(111)/Yttria-stabilized Zirconia\n(YSZ) nanoscale films by all-optical pump-probe measurements. The intrinsic\ndamping constant of the defect-free Fe$_3$O$_4$ film is found to be strikingly\nlarger than that of the as-grown Fe$_3$O$_4$ film with structural defects. We\ndemonstrate that the population of the first-order perpendicular standing spin\nwave (PSSW) mode, which is exclusively observed in the defect-free film under\nsufficiently high external magnetic fields, leads to the enhancement of the\nmagnetic damping of the uniform precession (Kittel) mode. We propose a physical\npicture in which the PSSW mode acts as an additional channel for the extra\nenergy dissipation of the Kittel mode. The energy transfer from Kittel mode to\nPSSW mode increases as in-plane magnetization precession becomes more uniform,\nresulting in the unique intrinsic magnetic damping enhancement in the\ndefect-free Fe$_3$O$_4$ film.",
        "positive": "Tunable stress and controlled thickness modification in graphene by\n  annealing: Graphene has many unique properties which make it an attractive material for\nfundamental study as well as for potential applications. In this paper, we\nreport the first experimental study of process-induced defects and stress in\ngraphene using Raman spectroscopy and imaging. While defects lead to the\nobservation of defect-related Raman bands, stress causes shift in phonon\nfrequency. A compressive stress (as high as 2.1 GPa) was induced in graphene by\ndepositing a 5 nm SiO2 followed by annealing, whereas a tensile stress (~ 0.7\nGPa) was obtained by depositing a thin silicon capping layer. In the former\ncase, both the magnitude of the compressive stress and number of graphene\nlayers can be controlled or modified by the annealing temperature. As both the\nstress and thickness affect the physical properties of graphene, this study may\nopen up the possibility of utilizing thickness and stress engineering to\nimprove the performance of graphene-based devices. Local heating techniques may\nbe used to either induce the stress or reduce the thickness selectively."
    },
    {
        "anchor": "In situ characterization of vacancy ordering in Ge-Sb-Te phase-change\n  memory alloys: Tailoring the degree of structural disorder in Ge-Sb-Te alloys is important\nfor the development of non-volatile phase-change memory and neuro-inspired\ncomputing. Upon crystallization from the amorphous phase, these alloys form a\ncubic rocksalt-like structure with a high content of intrinsic vacancies.\nFurther thermal annealing results in a gradual structural transition towards a\nlayered structure and an insulator-to-metal transition. In this work, we\nelucidate the atomic-level details of the structural transition in crystalline\nGeSb2Te4 by in situ high-resolution transmission electron microscopy (HRTEM)\nexperiments and ab initio density functional theory (DFT) calculations,\nproviding a comprehensive real-time and real-space view of the vacancy ordering\nprocess. We also discuss the impact of vacancy ordering on altering the\nelectronic and optical properties of GeSb2Te4, which is relevant to multilevel\nstorage applications. The phase evolution paths in Ge-Sb-Te alloys are\nillustrated using a summary diagram, which serves as a guide for designing\nphase-change memory devices.",
        "positive": "Photovoltaic performance of n-type SnS active layer in\n  ITO/PEDOT:PSS/SnS/Al structure: The present paper discusses the influence of Tin Sulphide's grain size on the\nperformance of ITO/PEDOT:PSS/SnS/Al structured solar cells fabricated by\nthermal evaporation. The grain sizes were maintained in the range of 11-18~nm\nby controlling the thickness of SnS films. While the open circuit voltage (Voc)\nwas found to be a constant for this structure, Parameters such as short circuit\ncurrent density (Jsc), series resistance (Rs), parallel resistance (Rp),\nideality factor and the overall efficiency were found to be dependent on the\nSnS grain size and incident light intensity. The experimental work directly\nreconfirms the theoretical results and ideas raised in literature by early\nresearchers."
    },
    {
        "anchor": "Giant Magnetoelectric Effect via Strain-Induced Spin-Reorientation\n  Transitions in Ferromagnetic Films: It is shown theoretically that a giant magnetoelectric susceptibility\nexceeding 10^-6 s/m may be achieved in the ferromagnetic/ferroelectric\nepitaxial systems via the magnetization rotation induced by an electric field\napplied to the substrate. The predicted magnetoelectric anomaly results from\nthe strain-driven spin-reorientation transitions in ferromagnetic films, which\ntake place at experimentally accessible misfit strains in CoFe2O4 and Ni films.",
        "positive": "Real-space study of the growth of magnesium on ruthenium: The growth of magnesium on ruthenium has been studied by low-energy electron\nmicroscopy (LEEM) and scanning tunneling microscopy (STM). In LEEM, a\nlayer-by-layer growth is observed except in the first monolayer, where the\ncompletion of the first layer in inferred by a clear peak in electron\nreflectivity. Desorption from the films is readily observable at 400 K.\nReal-space STM and low-energy electron diffraction confirm that sub-monolayer\ncoverage presents a moir\\'e pattern with a 1.2 nm periodicity, which evolves\nwith further Mg deposition by compressing the Mg layer to a 2.2 nm periodicity.\nLayer-by-layer growth is followed in LEEM up to 10 ML. On films several ML\nthick a substantial density of stacking faults are observed by dark-field\nimaging on large terraces of the substrate, while screw dislocations appear in\nthe stepped areas. The latter are suggested to result from the mismatch in\nheights of the Mg and Ru steps. Quantum size effect oscillations in the\nreflected LEEM intensity are observed as a function of thickness, indicating an\nabrupt Mg/Ru interface."
    },
    {
        "anchor": "Ion irradiation and implantation modifications of magneto-ionically\n  induced exchange bias in Gd/NiCoO: Magneto-ionic control of magnetic properties through ionic migration has\nshown promise in enabling new functionalities in energy-efficient spintronic\ndevices. In this work, we demonstrate the effect of helium ion irradiation and\noxygen implantation on magneto-ionically induced exchange bias effect in\nGd/Ni$_{0.33}$Co$_{0.67}$O heterostructures. Irradiation using $He^+$ leads to\nan expansion of the Ni$_{0.33}$Co$_{0.67}$O lattice due to strain relaxation.\nAt low He+ fluence ($\\leq$ 2$\\times$10$^{14}$ ions cm$^{-2}$), the\nredox-induced interfacial magnetic moment initially increases, owing to\nenhanced oxygen migration. At higher fluence, the exchange bias is suppressed\ndue to reduction of pinned uncompensated interfacial Ni$_{0.33}$Co$_{0.67}$O\nspins. For oxygen implanted samples, an initial lattice expansion below a dose\nof 5$\\times$10$^{15}$ cm$^{-2}$ is subsequently dominated at higher dose by a\nlattice contraction and phase segregation into NiO and CoO-rich phases, which\nin turn alters the exchange bias. These results highlight the possibility of\nion irradiation and implantation as an effective means to tailor magneto-ionic\neffects.",
        "positive": "Ferromagnetism of sputtered Fe3GeTe2 ultrathin films in the absence of\n  two-dimensional crystalline order: The discovery of ferromagnetism in two-dimensional (2D) monolayers has\nstimulated growing research interest in both spintronics and material science.\nHowever, these 2D ferromagnetic layers are mainly prepared through an\nincompatible approach for large-scale fabrication and integration, and\nmoreover, a fundamental question whether the observed ferromagnetism actually\ncorrelates with the 2D crystalline order has not been explored. Here, we choose\na typical 2D ferromagnetic material, Fe3GeTe2, to address these two issues by\ninvestigating its ferromagnetism in an amorphous state. We have fabricated\nnanometer-thick amorphous Fe3GeTe2 films approaching the monolayer thickness\nlimit of crystallized Fe3GeTe2 (0.8 nm) through magnetron sputtering. Compared\nto crystallized Fe3GeTe2, we found that the basic ferromagnetic attributes,\nsuch as the Curie temperature that directly reflects magnetic exchange\ninteractions and local anisotropic energy, do not change significantly in the\namorphous states. This is attributed to that the short-range atomic order, as\nconfirmed by valence state analysis, is almost the same for both phases. The\npersistence of ferromagnetism in the ultrathin amorphous counterpart has also\nbeen confirmed through magnetoresistance measurements, where two unconventional\nswitching dips arising from electrical transport within domain walls are\nclearly observed in the amorphous Fe3GeTe2 single layer. These results indicate\nthat the long-range ferromagnetic order of crystallized Fe3GeTe2 may not\ncorrelate to the 2D crystalline order and the corresponding ferromagnetic\nattributes can be utilized in an amorphous state which suits large-scale\nfabrication in a semiconductor technology-compatible manner for spintronics\napplications."
    },
    {
        "anchor": "Fermi surface and electron dispersions of PbTe doped with resonant Tl\n  impurity from KKR-CPA calculations: We present results of detailed study on the electron dispersions and Fermi\nsurface of lead telluride doped with $2\\%$ of thallium, which is resonant\nimpurity in PbTe. Using the KKR--CPA method, Bloch spectral functions (BSFs),\nwhich replace the dispersion relations in alloys, are calculated, and BSFs\nintensity maps over the Brillouin zone (alloy Fermi surface cross-sections) are\npresented. It is shown, that close to the valence band edge, Tl does not create\nan isolated impurity band, but due to its resonant character, strongly disturbs\nthe host electronic bands, leading to disappearance of sharp and well defined\nelectronic energy bands. Consequences of this effect on the transport\nproperties are discussed and new qualitative explanation of the improvement in\nthermoelectric properties of PbTe:Tl is suggested.",
        "positive": "Density functional study of oxygen vacancies at the SnO2 surface and\n  subsurface sites: Oxygen vacancies at the SnO2(110) and (101) surface and subsurface sites have\nbeen studied in the framework of density functional theory by using both\nall-electron Gaussian and pseudopotential plane-wave methods. The all-electron\ncalculations have been performed using the B3LYP exchange-correlation\nfunctional with accurate estimations of energy gaps and density of states. We\nshow that bulk oxygen vacancies are responsible for the appearance of a fully\noccupied flat energy level lying at about 1 eV above the top valence band, and\nan empty level resonant with the conduction band. Surface oxygen vacancies\nstrongly modify the surface band structures with the appearance of intragap\nstates covering most of the forbidden energy window, or only a small part of\nit, depending on the vacancy depth from the surface. Oxygen vacancies can\naccount for electron affinity variations with respect to the stoichiometric\nsurfaces as well. A significant support to the present results is found by\ncomparing them to the available experimental data."
    },
    {
        "anchor": "Adsorption and dissociation of iron phthalocyanine on H/Si(111): Impact\n  of van-der-Waals interactions and perspectives for subsurface doping: The adsorption of iron phthalocyanine (FePc) on the passivated H/Si(111)\nsurface is explored from first principles. We find that the organic molecule is\npredominantly physisorbed with a distance to the surface of $2.6 \\pm 0.1$\nAngstrom, but also exhibits sizable resonance with the underlying substrate.\nThis establishes the present system as interesting mixed\ncovalent-van-der-Waals-bound test case, which we use to compare the impact of\ndifferent approaches to van-der-Waals interactions. (Spin-polarized) scanning\ntunneling microscopy (SP STM) images are simulated, selectively accessing\ndifferent molecular orbitals via the applied bias voltage in the spirit of\nscanning tunneling spectroscopy. Comparison with experimental STM images\nreveals very good agreement. We find a significant magnetic contrast exceeding\n$\\pm 1$ Angstrom in the SP STM images for $-2$ and $+1.5$ V. Binding energies\nof different (transition metal) atoms in the center of the Pc ring are\npresented, which particularly show that Fe is strongly bound in the molecule\n(about $9.6$ eV). Finally, we discuss different reactions for subsurface doping\nby room-temperature FePc deposition and point out two feasible reactions.",
        "positive": "Scaling Behaviour and Complexity of the Portevin-Le Chatelier Effect: The plastic deformation of dilute alloys is often accompanied by plastic\ninstabilities due to dynamic strain aging and dislocation interaction. The\nrepeated breakaway of dislocations from and their recapture by solute atoms\nleads to stress serrations and localized strain in the strain controlled\ntensile tests, known as the Portevin-Le Chatelier (PLC) effect. In this present\nwork, we analyse the stress time series data of the observed PLC effect in the\nconstant strain rate tensile tests on Al-2.5%Mg alloy for a wide range of\nstrain rates at room temperature. The scaling behaviour of the PLC effect was\nstudied using two complementary scaling analysis methods: the finite variance\nscaling method and the diffusion entropy analysis. From these analyses we could\nestablish that in the entire span of strain rates, PLC effect showed Levy walk\nproperty. Moreover, the multiscale entropy analysis is carried out on the\nstress time series data observed during the PLC effect to quantify the\ncomplexity of the distinct spatiotemporal dynamical regimes. It is shown that\nfor the static type C band, the entropy is very low for all the scales compared\nto the hopping type B and the propagating type A bands. The results are\ninterpreted considering the time and length scales relevant to the effect."
    },
    {
        "anchor": "Orbital torque switching in perpendicularly magnetized materials: The orbital Hall effect in light materials has attracted considerable\nattention for developing novel orbitronic devices. Here we investigate the\norbital torque efficiency and demonstrate the switching of the perpendicularly\nmagnetized materials through the orbital Hall material (OHM), i.e., Zirconium\n(Zr). The orbital torque efficiency of approximately 0.78 is achieved in the Zr\nOHM with the perpendicularly magnetized [Co/Pt]3 sample, which significantly\nsurpasses that of the perpendicularly magnetized CoFeB/Gd/CoFeB sample\n(approximately 0.04). Such notable difference is attributed to the different\nspin-orbit correlation strength between the [Co/Pt]3 sample and the\nCoFeB/Gd/CoFeB sample, which has been confirmed through the theoretical\ncalculations. Furthermore, the full magnetization switching of the [Co/Pt]3\nsample with a switching current density of approximately 2.6x106 A/cm2 has been\nrealized through Zr, which even outperforms that of the W spin Hall material.\nOur finding provides a guideline to understand orbital torque efficiency and\npaves the way to develop energy-efficient orbitronic devices.",
        "positive": "Gate-Tunable Exchange Coupling Between Cobalt Clusters on Graphene: We use spin-density-functional theory (SDFT) ab initio calculations to\ntheoretically explore the possibility of achieving useful gate control over\nexchange coupling between cobalt clusters placed on a graphene sheet. By\napplying an electric field across supercells we demonstrate that the exchange\ninteraction is strongly dependent on gate voltage, but find that it is also\nsensitive to the relative sublattice registration of the cobalt clusters. We\nuse our results to discuss strategies for achieving strong and reproducible\nmagneto-electric effects in graphene/transition-metal hybrid systems."
    },
    {
        "anchor": "Atomistic modelling of the Shape Memory Effect: This paper reviews the status of molecular dynamics as a method in describing\nsolid-solid phase transitions, and its relationship to continuum approaches.\nSimulation work done in NiTi and Zr using first principles and semi-empirical\npotentials is presented. This shows failures of extending equilibrium\nthermodynamics to the nanoscale, and the crucial importance of system-specific\ndetails to the dynamics of martensite formation. The inconsistency between\nexperimental and theoretical crystal structures in NiTi is described, together\nwith its possible resolution in terms of nanoscale effects.",
        "positive": "Self-learning kinetic Monte Carlo model for arbitrary surface\n  orientations: While the self-learning kinetic Monte Carlo (SLKMC) method enables the\ncalculation of transition rates from a realistic potential, implementations of\nit were usually limited to one specific surface orientation. An example is the\nfcc (111) surface in Latz et al. 2012, J. Phys.: Condens. Matter 24, 485005.\nThis work provides an extension by means of detecting the local orientation,\nand thus allows for the accurate simulation of arbitrarily shaped surfaces. We\napplied the model to the diffusion of Ag monolayer islands and voids on a\nAg(111) and Ag(001) surface, as well as the relaxation of a three-dimensional\nspherical particle."
    },
    {
        "anchor": "Study the effect of scratching depth and ceramic-metal ratio on the\n  scratch behavior of NbC/Nb Ceramic/Metal nano-laminates using molecular\n  dynamics simulation and machine learning: Developing a new class of coating materials is necessary to meet the\nincreasing demands of energy and defense-related technologies, aerospace\nengineering, and harsh environmental conditions. Functional-based coatings,\nsuch as ceramic-metal nanolaminates, have gained popularity due to their\nability to be customized according to specific requirements. To design and\ndevelop advanced coatings with the necessary functionalities, it is crucial to\nunderstand the effects of various parameters on the mechanical and tribological\nproperties of these coatings. In this study, we investigate the impact of\npenetration depth, individual layer thickness, and ceramic-metal ratio on the\nmechanical and tribological properties of ceramic-metal nanolaminates,\nparticularly NbC/Nb. Our findings reveal that the thickness of the individual\nmetallic and ceramic layers significantly affects the coatings' properties.\nHowever, some models exhibited punctures on the top ceramic layer, which\naltered the scratching behavior and reduced the impact of layer thickness on\nit. This is because the top ceramic layer's thickness is too low, and the\nindenter can easily puncture it instead of pushing the ceramic atoms. The\nminimum thickness required to resist indentation is called the critical\nthickness, which depends on the indentation size and penetration depth. In the\nlatter part of this paper, we employed machine learning to reduce computational\ncosts, and the model predicts the friction coefficient with an R-squared value\nof 0.958.",
        "positive": "Ultra-high frequency magnetic resonance through strain-spin coupling in\n  perpendicular magnetic multi-layers: The interaction between strain and spin has received intensive attention in\nthe scientific community due to its abundant physical phenomena and huge\ntechnological impact. Until now, there is no experimental report on ultra-high\nfrequency magnetic resonance through the strain-spin coupling for any\ntechnologically relevant perpendicular magnetic material. Here we report the\nexperimental detection of the acoustic strain waves that have a response time\non the order of 10 picoseconds in perpendicular magnetic [Co/Pd]n multilayers\nvia a femtosecond laser pulse excitation. Through direct measurements of\nacoustic strain waves, we observe an ultra-high frequency magnetic resonance up\nto 60 GHz in [Co/Pd]n multilayers. We further report a theoretical model of the\nstrain-spin interaction. Our model reveals that the energy could be transferred\nefficiently from the strain to the spins and well explains the existence of a\nsteady resonance state through exciting the spin system. The physical origins\nof the resonance between strain waves and magnetic precession and the requested\nconditions for obtaining magnetic resonance within thin magnetic films have\nalso been discussed after thorough analysis. These combined results point out a\npotential pathway to enable an extremely high frequency (EHF) magnetic\nresonance through the strain-spin coupling."
    },
    {
        "anchor": "Reference levels, signal forms and determination of emission factor in\n  DLTS: The existence of reference levels of signals which determine directly the\ntemperature dependence of emission factor in deep level transient phenomena is\ndiscussed. The basic algebraic structure of reference levels in the classical\nDLTS is studied and various signal forms with derived reference levels are\ngiven. We then demonstrate the use of these signal forms and compare them with\nthe classical DLTS double boxcar signal.",
        "positive": "Direct Observation of Massless Domain Wall Dynamics in Nanostripes with\n  Perpendicular Magnetic Anisotropy: Domain wall motion induced by nanosecond current pulses in nanostripes with\nperpendicular magnetic anisotropy (Pt/Co/AlO$_x$) is shown to exhibit\nnegligible inertia. Time-resolved magnetic microscopy during current pulses\nreveals that the domain walls start moving, with a constant speed, as soon as\nthe current reaches a constant amplitude, and no or little motion takes place\nafter the end of the pulse. The very low 'mass' of these domain walls is\nattributed to the combination of their narrow width and high damping parameter\n$\\alpha$. Such a small inertia should allow accurate control of domain wall\nmotion, by tuning the duration and amplitude of the current pulses."
    },
    {
        "anchor": "Anisotropic Dirac electronic structures of AMnBi$_2$ (A=Sr, Ca): Low energy electronic structures in AMnBi2 (A=alkaline earths) are\ninvestigated using a first-principles calculation and a tight binding method.\nAn anisotropic Dirac dispersion is induced by the checkerboard arrangement of A\natoms above and below the Bi square net in AMnBi2. SrMnBi2 and CaMnBi2 have a\ndifferent kind of Dirac dispersion due to the different stacking of nearby A\nlayers, where each Sr (Ca) of one side appears at the overlapped (alternate)\nposition of the same element at the other side. Using the tight binding\nanalysis, we reveal the chirality of the anisotropic Dirac electrons as well as\nthe sizable spin-orbit coupling effect in the Bi square net. We suggest that\nthe Bi square net provides a platform for the interplay between anisotropic\nDirac electrons and the neighboring environment such as magnetism and\nstructural changes.",
        "positive": "Oxygen Vacancy Formation Energy in Metal Oxides: High Throughput\n  Computational Studies and Machine Learning Predictions: The oxygen vacancy formation energy ($\\Delta E_{vf}$) governs defect dynamics\nand is a useful metric to perform materials selection for a variety of\napplications. However, density functional theory (DFT) calculations of $\\Delta\nE_{vf}$ come at a greater computational cost than the typical bulk calculations\navailable in materials databases due to the involvement of multiple\nvacancy-containing supercells. As a result, available repositories of direct\ncalculations of $\\Delta E_{vf}$ remain relatively scarce, and the development\nof machine learning models capable of delivering accurate predictions is of\ninterest. In the present, work we address both such points. We first report the\nresults of new high-throughput DFT calculations of oxygen vacancy formation\nenergies of the different unique oxygen sites in over 1000 different oxide\nmaterials, which together form the largest dataset of directly computed oxygen\nvacancy formation energies to date, to our knowledge. We then utilize the\nresulting dataset of $\\sim$2500 $\\Delta E_{vf}$ values to train random forest\nmodels with different sets of features, examining both novel features\nintroduced in this work and ones previously employed in the literature. We\ndemonstrate the benefits of including features that contain information\nspecific to the vacancy site and account for both cation identity and oxidation\nstate, and achieve a mean absolute error upon prediction of $\\sim$0.3 eV/O,\nwhich is comparable to the accuracy observed upon comparison of DFT\ncomputations of oxygen vacancy formation energy and experimental results.\nFinally, we demonstrate the predictive power of the developed models in the\nsearch for new compounds for solar-thermochemical water-splitting applications,\nfinding over 250 new AA$^{\\prime}$BB$^{\\prime}$O$_6$ double perovskite\ncandidates."
    },
    {
        "anchor": "How to Report and Benchmark Emerging Field-Effect Transistors: Emerging low-dimensional nanomaterials have been studied for decades in\ndevice applications as field-effect transistors (FETs). However, properly\nreporting and comparing device performance has been challenging due to the\ninvolvement and interlinking of multiple device parameters. More importantly,\nthe interdisciplinarity of this research community results in a lack of\nconsistent reporting and benchmarking guidelines. Here we report a consensus\namong the authors regarding guidelines for reporting and benchmarking important\nFET parameters and performance metrics. We provide an example of this reporting\nand benchmarking process for a two-dimensional (2D) semiconductor FET. Our\nconsensus will help promote an improved approach for assessing device\nperformance in emerging FETs, thus aiding the field to progress more\nconsistently and meaningfully.",
        "positive": "Role of intersublattice exchange interaction on ultrafast longitudinal\n  and transverse magnetization dynamics in Permalloy: We report about element specific measurements of ultrafast demagnetization\nand magnetization precession damping in Permalloy (Py) thin films.\nMagnetization dynamics induced by optical pump at $1.5$eV is probed\nsimultaneously at the $M_{2,3}$ edges of Ni and Fe with High order Harmonics\nfor moderate demagnetization rates (less than $50$%). The role of the\nintersublattice exchange interaction on both longitudinal and transverse\ndynamics is analyzed with a Landau Lifshitz Bloch description of\nferromagnetically coupled Fe and Ni sublattices. It is shown that the\nintersublattice exchange interaction governs the dissipation during\ndemagnetization as well as precession damping of the magnetization vector."
    },
    {
        "anchor": "Ca$_{3}$Ru$_{2}$O$_{7}$: Interplay among degrees of freedom and the role\n  of the exchange-correlation: Ca$_{3}$Ru$_{2}$O$_{7}$ is a fascinating material that displays physical\nproperties governed by spin-orbit interactions and structural distortions,\nshowing a wide range of remarkable electronic phenomena. Here, we present a\ndensity-functional-based analysis of the interplay among degrees of freedom,\nsuch as magnetism, Coulomb repulsion (Hubbard-U), and structural degrees of\nfreedom, considering two exchange-correlation methods: Local-Density\nApproximation (LDA) and Perdew-Burke-Ernzerhof revised for solids (PBEsol). Our\ngoal is twofold: first, to provide a brief overview of the current state of the\nart on this compound underpinning the last proposed theoretical models and\nexperimental research, and second, to give another view to model the electronic\nproperties compared with the previous theoretical models. Our findings show\nthat Ca$_{3}$Ru$_{2}$O$_{7}$ displays several electronic states (metal,\nsemimetal, and narrow insulator) as a function of Hubbard-U while it exhibits\nstructural transition depending on the functional. We disentangle the effect of\nthe different degrees of freedom involved, clarifying the role of\nexchange-correlation in the observed electronic and structural transitions.",
        "positive": "Synthesizing Skyrmion Molecules in Fe-Gd Thin Films: We show that properly engineered amorphous Fe-Gd alloy thin films with\nperpendicular magnetic anisotropy exhibit room-temperature skyrmion molecules,\nor a pair of like-polarity, opposite-helicity skyrmions. Magnetic mirror\nsymmetry planes present in the stripe phase, instead of chiral exchange,\ndetermine the internal skyrmion structure and the net achirality of the\nskyrmion phase. Our study shows that stripe domain engineering in amorphous\nalloy thin films may enable the creation of skyrmion phases with\ntechnologically desirable properties."
    },
    {
        "anchor": "Current Control of Magnetic Anisotropy via Stress in a Ferromagnetic\n  Metal Waveguide: We demonstrate that in-plane charge current can effectively control the spin\nprecession resonance in an Al2O3/CoFeB/Ta heterostructure. Brillouin Light\nScattering (BLS) was used to detect the ferromagnetic resonance field under\nmicrowave excitation of spin waves at fixed frequencies. The current control of\nspin precession resonance originates from modification of the in-plane uniaxial\nmagnetic anisotropy field H_k, which changes symmetrically with respect to the\ncurrent direction. Numerical simulation suggests that the anisotropic stress\nintroduced by Joule heating plays an important role in controlling H_k. These\nresults provide new insights into current manipulation of magnetic properties\nand have broad implications for spintronic devices.",
        "positive": "Model for a collimated spin wave beam generated by a single layer, spin\n  torque nanocontact: A model of spin torque induced magnetization dynamics based upon\nsemi-classical spin diffusion theory for a single layer nanocontact is\npresented. The model incorporates effects due to the current induced Oersted\nfield and predicts the generation of a variety of spatially dependent,\ncoherent, precessional magnetic wave structures. Directionally controllable\ncollimated spin wave beams, vortex spiral waves, and localized standing waves\nare found to be excited by the interplay of the Oersted field and the\norientation of an applied field. These fields act as a spin wave ``corral''\naround the nanocontact that controls the propagation of spin waves in certain\ndirections."
    },
    {
        "anchor": "Polymeric Squaraine Dyes as Electron Donors in Bulk Heterojunction Solar\n  Cells: A polysquaraine low band gap polymer was synthesized by Yamamoto coupling of\na monomeric dibromo indolenine squaraine dye. The resulting polymer has a\nweight average molar mass in the order of Mw ~30.000-50.000 and a\npolydispersity of ca. 1.7 as determined by gel-permeation chromatography (GPC).\nThe electronic properties of monomer and polymer were investigated by cyclic\nvoltammetry, absorption and emission spectroscopy. Owing to exciton coupling\nthe absorption bands of the polymer are red-shifted and strongly broadened\ncompared to the monomer squaraine dye. Bulk heterojunction solar cells were\nprepared from blends of the polysquaraine with the fullerene derivative\n[6,6]-phenyl C61-butyric acid methyl ester (PCBM) in different weight ratios\n(1:3 to 1:1). The power conversion efficiencies under simulated AM 1.5\nconditions yielded 0.45 % for these non-optimized systems. The external quantum\nefficiency (EQE) shows that the photoresponse spans the range from 300 to 850\nnm, which illustrates the promising properties of this novel organic\nsemiconductor as a low band gap donor material in organic photovoltaics.",
        "positive": "Reply to cond-mat/0111504: We show that the choice of the sign of the hopping matrix in our impurity\nband model for disordered III-V diluted magnetic semiconductors [PRL 87, 107293\n(2000); cond-mat/0111045] is justified: with this choice, the impurity band is\nplaced inside the gap and it has a mobility edge, as expected for a disordered\nsystem. The other sign choice, suggested in cond-mat/0111504, leads to an\nunphysical description of the occupied states of the impurity band (extremely\nlong tail, no mobility edge, no bulk ferromagnetism)."
    },
    {
        "anchor": "Surface Screening Mechanisms in Ferroelectric Thin Films and its Effect\n  on Polarization Dynamics and Domain Structures: For over 70 years, ferroelectric materials have been remaining one of the\ncentral research topics for condensed matter physics and material science, the\ninterest driven both by fundamental science and applications. However,\nferroelectric surfaces, the key component of ferroelectric films and\nnanostructures, still present a significant theoretical and even conceptual\nchallenge. Indeed, stability of ferroelectric phase per se necessitates\nscreening of polarization charge. At surfaces, this can lead to coupling\nbetween ferroelectric and semiconducting properties of material, or with\nsurface (electro) chemistry, going well beyond classical models applicable for\nferroelectric interfaces. In this review, we summarize recent studies of\nsurface screening phenomena in ferroelectrics. We provide a brief overview of\nthe historical understanding of physics of ferroelectric surfaces, and existing\ntheoretical models that both introduce screening mechanisms and explore the\nrelationship between screening and relevant aspects of ferroelectric\nfunctionalities starting from phase stability itself. Given that majority of\nferroelectrics exist in multiple-domain states, we focus on local studies of\nscreening phenomena using scanning probe microscopy techniques. We discuss\nrecent studies of static and dynamic phenomena on ferroelectric surfaces, as\nwell as phenomena observed under lateral transport, light, chemical, and\npressure stimuli. We also note that the need for ionic screening renders\npolarization switching a coupled physical-electrochemical process, and discuss\nthe non-trivial phenomena such as chaotic behavior during domain switching that\nstem from this.",
        "positive": "Hidden Magnetic Order in Triangular-Lattice Magnet Li2MnTeO6: The manganese tellurate Li2MnTeO6 consists of trigonal spin lattices made up\nof Mn4+ (d3, S = 3/2) ions. The magnetic properties of this compound were\ncharacterized by several experimental techniques, which include magnetic\nsusceptibility, specific heat, dielectric permittivity, electron spin resonance\n(ESR), nuclear magnetic resonance (NMR) and neutron powder diffraction (NPD)\nmeasurements, and by density functional calculations (DFT). The magnetic\nsusceptibility chi(T) demonstrates very unusual behavior. It isdescribed by the\nCurie-Weiss law at high temperature with Curie-Weiss temperature of Theta = -74\nK, exhibits no obvious anomaly indicative of a long-range magnetic ordering at\nlow magnetic fields. At high magnetic fields, however, the character of chi(T)\nchanges showing a maximum at about 9 K. That this maximum of chi(T) reflects\nthe onset of an antiferromagnetic order was confirmed by specific heat\nmeasurements, which exhibit a clear lambda-type anomaly at TN around 8.5 K even\nat zero magnetic field, and by 7Li NMR and dielectric permittivity\nmeasurements. The magnetic structure of Li2MnTeO6, determined by neutron powder\ndiffraction measurements at 1.6 K, is described by the 120-degree non-collinear\nspin structure with the propagation vector k = (1/3, 1/3, 0). Consistent with\nthis finding, the spin exchange interactions evaluated for Li2MnTeO6 by density\nfunctional calculations are dominated by the nearest-neighbor antiferromagnetic\nexchange within each triangular spin lattice. This spin lattice is strongly\nspin frustrated with f = |Theta|/TN around 8 and exhibits a two-dimensional\nmagnetic character in a broad temperature range above TN."
    },
    {
        "anchor": "First principles calculations of X-ray absorption in an ultrasoft\n  pseudopotentials scheme: from $\u03b1$-quartz to high-T$_c$ compounds: We develop a first-principles scheme based on the continued fraction approach\nan d ultrasoft pseudopotentials to calculate K-edge X-ray absorption spectra in\nsolids. The method allows for calculations of K-edge X-ray absorption spectra\nin transition metal and rare-earths compounds with substantially reduced\ncutoffs respect to the norm-conserving case. We validate the method by\ncalculating Si and O K-edges in $\\alpha$ quartz, Cu K-edge in Copper and in\nLa$_2$CuO$_4$. For the case of Si and O edges in $\\alpha$ quartz and in Copper\nwe obtain a good agreement with experimental data. In the Cu K-edge spectra of\nLa$_2$CuO$_4$, a material considered a real challeng e for density functional\ntheory we attribute all the near-edge and far-edge peaks to single particle\nexcitations.",
        "positive": "Accurate construction of transition metal pseudopotentials: We generate a series of pseudopotentials to examine the relationship between\npseudoatomic properties and solid-state results. We find that lattice constants\nand bulk moduli are quite sensitive to eigenvalue, total-energy difference and\ntail norm errors, and clear correlations emerge. These trends motivate our\nidentification of two criteria for accurate transition metal pseudopotentials.\nWe find that both the preservation of all-electron derivative of tail norm with\nrespect to occupation and the preservation of all-electron derivative of\neigenvalue with respect to occupation {[Phys. Rev. B {\\bf 48}, 5031 (1993)]}\nare necessary to give accurate bulk metal lattice constants and bulk moduli. We\nalso show how the fairly wide range of lattice constant and bulk modulus\nresults found in the literature can be easily explained by pseudopotential\neffects."
    },
    {
        "anchor": "New Diluted ferromagnetic semiconductor Li(Zn,Mn)P with decoupled charge\n  and spin doping: We report the discovery of a new diluted magnetic semiconductor, Li(Zn,Mn)P,\nin which charge and spin are introduced independently via lithium\noff-stoichiometry and the isovalent substitution of Mn2+ for Zn2+,\nrespectively. Isostructural to (Ga,Mn)As, Li(Zn,Mn)P was found to be a p-type\nferromagnetic semiconductor with excess Lithium providing charge doping. First\nprinciples calculations indicate that excess Li is favored to partially occupy\nthe Zn site, leading to hole doping. Ferromagnetism is mediated in\nsemiconducting samples of relative low mobile carriers with a small coercive\nforce, indicating an easy spin flip.",
        "positive": "Micro-plasticity and recent insights from intermittent and small-scale\n  plasticity: Prior to macroscopic yielding, most materials undergo a regime of plastic\nactivity that cannot be resolved in conventional bulk deformation experiments.\nIn this pre-yield, or micro-plastic regime, it is the initial three dimensional\ndefect network that is probed and the intermittently evolving microstructure\nadmits small increments in plastic strain. By reducing the sample size, this\nintermittent activity becomes increasingly apparent and can be routinely\nobserved through small-scale mechanical testing. In some cases, the\nintermittent activity was shown to exhibit aspects of scale-free behavior,\nprompting a paradigm shift away from traditional microstructure-dependent unit\nmechanisms that may be associated with a well defined length and stress scale.\nIn this article, we discuss and review connections between classical\nmicro-plasticity and intermittent flow across all length scales, with the aim\nof highlighting the value of miniaturized testing as a means to unravel this\nvery early regime of bulk plasticity."
    },
    {
        "anchor": "On the shear-affected zone of shear bands in bulk metallic glasses: Notched bars of bulk metallic glasses, Pd$_{40}$Ni$_{40}$P$_{20}$ and\nZr$_{52.5}$Cu$_{17.9}$Ni$_{14.6}$Al$_{10}$Ti$_{5}$, were deformed under 3-point\nbending conditions, resulting in the formation of shear bands before failure.\nThe immediate environment of shear bands was investigated in detail using\nfluctuation electron microscopy to extract information on the strain-induced\nmodifications of the medium-range order (MRO) and its lateral extension.\nCharacteristic material-independent gradients were observed for the tensile and\ncompressive sides of the samples indicating the impact of the local stress\nstate on the MRO. Our results reveal an upper limit of a few microns for the\nlateral extension of the shear-affected environments of shear bands.",
        "positive": "Particle size dependence of magnetization and non-centrosymmetry in\n  nanoscale BiFeO3: The saturation magnetization (M_s), antiferromagnetic transition point (T_N),\nand the off-center displacements of Bi and Fe ions have been measured as a\nfunction of particle size in nanoscale BiFeO3. T_N decreases down to ~550 K for\nparticles of size ~5 nm from ~653 K in bulk while M_s rises by more than an\norder of magnitude. Analysis of crystallographic structure from Rietveld\nrefinement of x-ray diffraction patterns shows significant rise in off-center\ndisplacements of Bi (del_Bi) and Fe (del_Fe) ions within a unit cell with the\ndecrease in particle size. The net unit-cell polarization P_S too, is found to\nbe larger in nanoscale regime."
    },
    {
        "anchor": "Dynamic Rashba-Dresselhaus Effect: The Rashba-Dresselhaus effect is the splitting of doubly degenerate band\nextrema in semiconductors, accompanied by the emergence of counter-rotating\nspin textures and spin-momentum locking. Here we investigate how this effect is\nmodified by lattice vibrations. We show that, in centrosymmetric non-magnetic\ncrystals, for which a bulk Rashba-Dresselhaus effect is symmetry-forbidden,\nelectron-phonon interactions can induce a phonon-assisted, dynamic\nRashba-Dresselhaus spin splitting in the presence of an out-of-equilibrium\nphonon population. In particular, we show how Rashba, Dresselhaus, or Weyl spin\ntextures can selectively be established by driving coherent infrared-active\nphonons, and we perform ab initio calculations to quantify this effect for\nhalide perovskites.",
        "positive": "Atomic structure of grain boundaries in iron modeled using the atomic\n  density function: A model based on the continuous atomic density function (ADF) approach is\napplied to predict the atomic structure of grain boundaries (GBs) in iron.\nSymmetrical [100] and [110] tilt GBs in bcc iron are modeled with the ADF\nmethod and relaxed afterwards in molecular dynamics (MD) simulations. The shape\nof the GB energy curve obtained in the ADF model reproduces well the\npeculiarities of the angles of 70.53 deg. [$\\Sigma$ 3(112)] and 129.52 deg.\n[$\\Sigma$ 11(332)] for [110] tilt GBs. The results of MD relaxation with an\nembedded-atom method potential for iron confirm that the atomic GB\nconfigurations obtained in ADF modeling are very close to equilibrium ones. The\ndeveloped model provides well-localized atomic positions for GBs of various\ngeometries."
    },
    {
        "anchor": "Quantifying the structural integrity of nanorod arrays: Arrays of aligned nanorods oriented perpendicular to a support, which are\naccessible by top-down lithography or by means of shape-defining hard\ntemplates, have received increasing interest as sensor components, components\nfor nanophotonics and nanoelectronics, substrates for tissue engineering,\nsur-faces having specific adhesive or antiadhesive properties and as surfaces\nwith customized wettability. Agglomeration of the nanorods deteriorates the\nperformance of components based on nanorod arrays. A comprehensive body of\nliterature deals with mechanical failure mechanisms of nanorods and design\ncriteria for mechanically stable nanorod arrays. However, the structural\nintegrity of nanorod arrays is commonly evaluated only visually and\nqualitatively. We use real-space analysis of microscopic images to quantify the\nfraction of condensed nanorods in nanorod arrays. We suggest the number of\narray elements apparent in the micrographs divided by the number of array\nelements a defect-free array would contain in the same area, referred to as\nintegrity fraction, as a measure of structural array integrity. Reproducible\nprocedures to determine the imaged number of array elements are introduced.\nThus, quantitative comparisons of different nanorod arrays, or of one nanorod\narray at different stages of its use, are possible. Structural integrities of\nidentical nanorod arrays differing only in the length of the nanorods are\nexemplarily analyzed.",
        "positive": "Chemical-state analyses of Ni, Zn, and W ions in NiWO$_4$-ZnWO$_4$ solid\n  solutions by X-ray photoelectron spectroscopy: The chemical states of Ni, Zn, and W in microcrystalline NiWO$_4$-ZnWO$_4$\nsolid solutions were studied by X-ray photoelectron spectroscopy. The recorded\nspectra of the Ni 2p, Zn 2p, and W 4f photoelectron lines and Ni\nL$_2$M$_{23}$M$_{45}$, Zn L$_3$M$_{45}$M$_{45}$, and W N$_4$N$_{67}$N$_{7}$\nAuger-transition lines show pronounced changes with increasing Zn\nconcentration. The positions of the resolved photoelectron and Auger-transition\nlines were combined to construct so-called chemical-state plots (Wagner or\nAuger-parameter plots) for metal ions in solid solutions. With increasing Zn\nconcentration, the Auger parameter increases for Ni and decreases for W, thus\nevidencing a lowering and an increase of the electronic polarizability around\ncore-ionized Ni and W ions, respectively. At the same time, the character of\nZn-O bonds and the local structure around Zn ions do not change. It is\nconcluded that the dilution of NiWO$_4$ with Zn ions is accompanied by an\nincrease of the Ni-O bond ionicity and an increase of the W-O bond covalency.\nThese changes are attributed to the charge redistribution among [NiO$_6$] and\n[WO$_6$] structural units. We show that a careful in-depth analysis of XPS data\nobtained with a laboratory-based X-ray photoelectron spectroscopy system can\ngive chemically sensitive, qualitative information on the changes in the first\ncoordination spheres of each metal ion. This information is otherwise\naccessible only by synchrotron-based techniques (such as X-ray absorption\nspectroscopy)."
    },
    {
        "anchor": "Strain effects on the ionic conductivity of Y-doped ceria: A simulation\n  study: In this paper we report a computational study of the effects of strain on the\nconductivity of Y-doped ceria (YDC). This material was chosen as it is of\ntechnological interest in the field of Solid Oxide Fuel Cells (SOFCs). The\nsimulations were performed under realistic operational temperatures and strain\n(\\epsilon) levels. For bulk and thin film YDC, the results show that tensile\nstrain leads to conductivity enhancements of up to 3.5x and 1.44x,\nrespectively. The magnitude of these enhancements is in agreement with recent\nexperimental and computational evidence. In addition, the methods presented\nherein allowed us to identify enhanced ionic conductivity in the surface\nregions of YDC slabs and its anisotropic character.",
        "positive": "Two-valence band electron and heat transport in monocrystalline\n  PbTe-CdTe solid solutions with high Cd content: High quality p-type PbTe-CdTe monocrystalline alloys containing up to 10\nat.$\\%$ of Cd are obtained by self-selecting vapor transport method. Mid\ninfrared photoluminescence experiments are performed to follow the variation of\nthe fundamental energy gap as a function of Cd content. The Hall mobility,\nthermoelectric power, thermal conductivity and thermoelectric figure of merit\nparameter $ZT$ are investigated experimentally and theoretically paying\nparticular attention to the two-valence band structure of the material. It is\nshown that the heavy-hole band near the $\\Sigma$ point of the Brillouin zone\nplays an important role and is responsible for the Pb$_{1-x}$Cd$_x$Te hole\ntransport at higher Cd-content. Our data and their description can serve as the\nstandard for Pb$_{1-x}$Cd$_x$Te single crystals with $x$ up to 0.1. It is\nshown, that monocrystalline Pb$_{1-x}$Cd$_x$Te samples with relatively low Cd\ncontent of about 1 at.\\% and hole concentration of the order of 10$^{20}$\ncm$^{-3}$ may exhibit $ZT \\approx$ 1.4 at 600 K."
    },
    {
        "anchor": "ZnO/a-Si Distributed Bragg Reflectors for Light Trapping in Thin Film\n  Solar Cells from Visible to Infrared Range: Distributed bragg reflectors (DBRs) consisting of ZnO and amorphous silicon\n(a-Si) were prepared by magnetron sputtering method for selective light\ntrapping. The quarter-wavelength ZnO/a-Si DBRs with only 6 periods exhibit a\npeak reflectance of above 99% and have a full width at half maximum that is\ngreater than 347 nm in the range of visible to infrared. The 6-pair reversed\nquarter-wavelength ZnO/a-Si DBRs also have a peak reflectance of 98%.\nCombination of the two ZnO/a-Si DBRs leads to a broader stopband from 686 nm to\n1354 nm. Using the ZnO/a-Si DBRs as the rear reflector of a-Si thin film solar\ncells significantly increases the photocurrent in the spectrum range of 400 nm\nto 1000 nm, in comparison with that of the cells with Al reflector. The\nobtained results suggest that ZnO/a-Si DBRs are promising reflectors of a-Si\nthin-film solar cells for light trapping.",
        "positive": "Full optimization of quasiharmonic free energy with anharmonic lattice\n  model: Application to thermal expansion and pyroelectricity of wurtzite GaN\n  and ZnO: We present a theory and a calculation scheme of structural optimization at\nfinite temperatures within the quasiharmonic approximation (QHA). The theory is\nbased on an efficient scheme of updating the interatomic force constants with\nthe change of crystal structures, which we call the IFC renormalization. The\ncell shape and the atomic coordinates are treated equally and simultaneously\noptimized. We apply the theory to the thermal expansion and the pyroelectricity\nof wurtzite GaN and ZnO, which accurately reproduces the experimentally\nobserved behaviors. Furthermore, we point out a general scheme to obtain\ncorrect $T$ dependence at the lowest order in constrained optimizations that\nreduce the number of effective degrees of freedom, which is helpful to perform\nefficient QHA calculations with little sacrificing accuracy. We show that the\nscheme works properly for GaN and ZnO by comparing with the optimization of all\nthe degrees of freedom."
    },
    {
        "anchor": "Imaging microscopic electronic contrasts at the interface of\n  single-layer WS$_2$ with oxide and boron nitride substrates: The electronic properties of devices based on two-dimensional materials are\nsignificantly influenced by interactions with substrate and electrode\nmaterials. Here, we use photoemission electron microscopy to investigate the\nreal- and momentum-space electronic structures of electrically contacted\nsingle-layer WS$_2$ stacked on hBN, SiO$_2$ and TiO$_2$ substrates. Using work\nfunction and X-ray absorption imaging we single-out clean microscopic regions\nof each interface type and collect the valence band dispersion. We infer the\nalignments of the electronic band gaps and electron affinities from the\nmeasured valence band offsets of WS$_2$ and the three substrate materials using\na simple electron affinity rule and discuss the implications for vertical band\nstructure engineering using mixed three- and two-dimensional materials.",
        "positive": "Thermal Control of the Magnon-Photon Coupling in a Notch Filter coupled\n  to a Yttrium-Iron-Garnet/Platinum System: We report thermal control of mode hybridization between the ferromagnetic\nresonance (FMR) and a planar resonator (notch filter) working at 4.74 GHz. The\nchosen magnetic material is a ferrimagnetic insulator (Yttrium Iron Garnet:\nYIG) covered by 6 nm of platinum (Pt). A current induced heating method has\nbeen used in order to enhance the temperature of the YIG/Pt system. The device\npermits us to control the transmission spectra and the magnon-photon coupling\nstrength at room temperature. These experimental findings reveal potentially\napplicable tunable microwave filtering function."
    },
    {
        "anchor": "Single-Crystal Growth and Thermoelectric Properties of Ge(Bi,Sb)4Te7: The thermoelectric properties between 10 and 300 K and the growth of single\ncrystals of n-type and p-type GeBi4Te7, GeSb4Te7, and the Ge(Bi1-xSbx)4Te7\nsolid solution are reported. Single crystals were grown by the modified\nBridgman method, and p-type behavior was achieved by the substitution of Bi by\nSb in GeBi4Te7. The thermopower in the Ge(Bi1-xSbx)4Te7 solid solution ranges\nfrom -117 muVK^-1 to +160 muVK^-1. The crossover from n-type to p-type is\ncontinuous with increasing Sb content and is observed at x = 0.15. The highest\nthermoelectric efficiencies among the tested n-type and p-type samples are ZnT\n= 0.11 and ZpT = 0.20, respectively. For an optimal n-p couple in this alloy\nsystem the composite figure of merit is ZnpT = 0.17 at room temperature.",
        "positive": "Pressure-induced phase transitions in AgClO4: AgClO4 has been studied under compression by x-ray diffraction and density\nfunctional theory calculations. Experimental evidence of a structural phase\ntransition from the tetragonal structure of AgClO4 to an orthorhombic\nbarite-type structure has been found at 5.1 GPa. The transition is supported by\ntotal-energy calculations. In addition, a second transition to a monoclinic\nstructure is theoretically proposed to take place beyond 17 GPa. The equation\nof state of the different phases is reported as well as the calculated\nRaman-active phonons and their pressure evolution. Finally, we provide a\ndescription of all the structures of AgClO4 and discuss their relationships.\nThe structures are also compared with those of AgCl in order to explain the\nstructural sequence determined for AgClO4."
    },
    {
        "anchor": "Experimental and Computational Studies of the Optical Properties of\n  CuAl1-xFexO2: Delafossites are promising candidates for photocatalysis applications because\nof their chemical stability and absorption in the solar region of the\nelectromagnetic spectrum. For example, CuAlO2 has good chemical stability but\nhas a large indirect bandgap (~3 eV), so that efforts to improve its absorption\nin the solar region through alloying are investigated. The effect of dilute\nalloying on the optical absorption of powdered CuAl1-xFexO2 (x = 0.0-1.0) is\nmeasured and compared to electronic band structures calculations using a\ngeneralized gradient approximation with Hubbard exchange-correlation parameter\nand spin. A new absorption feature is observed at 1.8 eV for x = 0.01, which\nredshifts to 1.4 eV for x = 0.10. This feature is associated with transitions\nfrom the L-point valence band maximum to the Fe-3d state that appears below the\nconduction band of the spin-down band structure. The feature increases the\noptical absorption below the bandgap of pure CuAlO2, making dilute CuAl1-xFexO2\nalloys better suited for solar photocatalysis.",
        "positive": "First principles modelling of magnesium titanium hydrides: Mixing Mg with Ti leads to a hydride Mg(x)Ti(1-x)H2 with markedly improved\n(de)hydrogenation properties for x < 0.8, as compared to MgH2. Optically, thin\nfilms of Mg(x)Ti(1-x)H2 have a black appearance, which is remarkable for a\nhydride material. In this paper we study the structure and stability of\nMg(x)Ti(1-x)H2, x= 0-1 by first-principles calculations at the level of density\nfunctional theory. We give evidence for a fluorite to rutile phase transition\nat a critical composition x(c)= 0.8-0.9, which correlates with the\nexperimentally observed sharp decrease in (de)hydrogenation rates at this\ncomposition. The densities of states of Mg(x)Ti(1-x)H2 have a peak at the Fermi\nlevel, composed of Ti d states. Disorder in the positions of the Ti atoms\neasily destroys the metallic plasma, however, which suppresses the optical\nreflection. Interband transitions result in a featureless optical absorption\nover a large energy range, causing the black appearance of Mg(x)Ti(1-x)H2."
    },
    {
        "anchor": "Adaptively compressed exchange in LAPW: We present an implementation of the adaptively compressed exchange (ACE)\noperator in the LAPW formalism. ACE is a low-rank representation of the Fock\nexchange that avoids any loss of precision for the total energy. Our study\nshows that this property remains in the all-electron case, as we apply this\nmethod in non-relativistic total-energy calculations with a hybrid\nexchange-correlation functional PBE0. The obtained data for light atoms and\nmolecules are within a few $\\mu$Ha off the precise multi-resolution-analysis\ncalculations. Aside from ACE, another key ingredient to achieve such a high\nprecision with Fock exchange was the use of high-energy local orbitals.\nFinally, we use this implementation to calculate PBE0 gaps in solids and\ncompare the results to other all-electron results.",
        "positive": "The influence of anisotropy on the evolution of interfacial morphologies\n  in directional solidification: A phase-field study: By adjusting the interface energy, curvature, and velocity, the anisotropy\nplays an important role in the interaction between interfacial processes and\ntransport processes, determining the solidification structures. In this paper,\nthrough the quantitative phase-field model, the influence of anisotropy on the\nevolution of interfacial morphologies in directional solidification is\ninvestigated. To represent different interfacial anisotropies, the\nsolidification processes with different preferred crystallographic orientations\nare performed. Then the effect of anisotropy on morphological evolution is\ndiscussed systematically. At the planar growth stage, the interfacial\nanisotropy makes no difference in the transport processes and morphological\nevolution. At the onset time of planar instability, the anisotropy determines\nthe detailed evolution by adjusting the interface stiffness. At the\nplanar-cellular-transition stage, with the influence of anisotropy, the\ninterfacial curvature decreases from {\\theta}0=0{\\deg} to {\\theta}0=40{\\deg}.\nHence, the solute concentration ahead of the interface increases from\n{\\theta}0=0{\\deg} to {\\theta}0=40{\\deg}, while the instantaneous velocity of\nthe interface decreases from {\\theta}0=0{\\deg} to {\\theta}0=40{\\deg}. At the\nquasi-steady-state stage, the anisotropy determines the growth direction and\ntip velocity of the primary dendrite, as well as the onset of sidebranches."
    },
    {
        "anchor": "Magnetoelastic coupling in BaTiO3-based multiferroic structures: Analytical expressions for the magnetoelastic anisotropy constants of cubic\nmagnetic systems are derived for rectangular and oblique distortions\noriginating from epitaxial growth on substrates with lower crystal symmetry. In\nparticular, the temperature variation of the magnetic properties of magnetic\nfilms grown on barium titanate (BaTiO3) substrates are explained in terms of\nstrain-induced magnetic anisotropies caused by the temperature dependent phase\ntransitions of BaTiO3. Our results quantify the experimental observations in\nferromagnet/\\bto-based structures, which have been proposed as templates for\nmagnetoelectric composite heterostructures.",
        "positive": "The Elusive member of the Ti-Al-C MAX family- Ti4AlC3: We report here perhaps the first successful synthesis and structural\ncharacterization of the n=3 family member of Tin+1AlCn, i. e. Ti4AlC3. X-ray\nPowder diffraction (XRD) data shows characteristic reflections of from\ncorresponding to reflections from the (002), (004), (006), (008), (100), (102),\n(104), (0010), (105), (106), (0012), (1011) and (1012) planes at 2{\\theta}\n=7.640, 15.170, 22.760, 30.50, 350, 37.40 38.30, 39.20, 41.30, 46.220, 55.240,\n58.620 and 60.780 (double structure) respectively. Rietveld refinement of the\nXRD data reveals a phase purity of about 79 % for alpha-Ti4AlC3, 15 % for\nbeta-Ti4AlC3 and the rest mostly that of cubic TiC (6 %). The primary crystal\nsymmetry of the two dominant phases is the hexagonal P63/mmc. The precursors\nchosen were TiH2, Al metal powder and Carbon powder in a molar ratio of\n3:1.2:2, which build the case for an Al-deficient condition. We adopted the\npressureless sintering technique at 13500 C with a dwelling time of 4 hours\nunder ultra-high vacuum of 10-7 mbar. The co-existence of trace amount of\nTi2AlC at 1350 deg C is proven by the small structure at 2{\\theta}=13.130. No\ntrace of oxides like Al2O3 or TiO2 was found in the end product. The line\nprofile width of XRD data indicates average grain size of the order of micro\nmeter. The Scanning Electron Microscopy images show highly lamellar stacked\ngrowth of almost a pure MAX (alpha or beta) phase and grain size of micron\norder, agreeing well with the XRD data."
    },
    {
        "anchor": "Radioactive isotopes reveal a non sluggish kinetics of grain boundary\n  diffusion in high entropy alloys: High entropy alloys (HEAs) have emerged as a new class of multicomponent\nmaterials, which have potential for high temperature applications. Phase\nstability and creep deformation, two key selection criteria for high\ntemperature materials, are predominantly influenced by the diffusion of\nconstituent elements along the grain boundaries (GBs). For the first time, GB\ndiffusion of Ni in chemically homogeneous CoCrFeNi and CoCrFeMnNi HEAs is\nmeasured by radiotracer analysis using the $^{63}$Ni isotope. Atom probe\ntomography confirmed the absence of elemental segregation at GBs that allowed\nreliable estimation of the GB width to be about 0.5 nm. Our GB diffusion\nmeasurements prove that a mere increase in number of constituent elements does\nnot lower the diffusion rates in HEAs, but the nature of added constituents\nplays a more decisive role. The GB energies in both HEAs are estimated at about\n0.8-0.9 J/m$^2$, they are found to increase significantly with temperature and\nthe effect is more pronounced for the CoCrFeMnNi alloy.",
        "positive": "Kinetic Monte Carlo modelling of Helium Bubble Nucleation onto Oxides in\n  the Fe-Ti-Y-O System: A Kinetic Monte Carlo (KMC) model was created to simulate the insertion of\ntransmutation He atoms into nanostructured ferritic alloys (NFAs) under neutron\nirradiation. Interstitial He atoms migrate through the NFA until becoming\ntrapped in bubbles of other He atoms and vacancies created from irradiation.\nThe Y-Ti-O nano-oxides in the NFAs were found to be effective in capturing\nthese He atoms and preventing bubbles from forming at the grain boundary and\nappear to replicate the characteristics (size and number density) observed in\nother experiments. The bubbles were found to prefer the <111> oxide interface\nas a nucleation site and the stable bubbles have a He/Vac ratio between 1.3 and\n1.8 He/Vac. The influence of He bubbles on the segregation of solutes to the\ngrain boundaries or on the stability of the nano-oxides were negligible."
    },
    {
        "anchor": "Molecular dynamics simulations of noble gas release from endohedral\n  fullerene clusters: We report the results of molecular dynamics simulations of the release of\nfive species of noble gas atoms trapped inside a small cluster of fullerenes in\nthe temperature range 4000K < T < 5000K. We find that larger noble gas atoms\nare generally released at a slower rate and that helium is released\nconsiderably more rapidly than any of the other noble gases. The differing\nrelease rates are due not only to the differences in the size and mass of a\ngiven endohedral species but also because larger trapped atoms tend to\nstabilize the fullerene cage against thermal fluctuations. Unlike with the case\nof atoms entering fullerenes, we find that any atom escaping from the cage\nresults in a window which does not close. Escape rate constants are reported\nand comparisons with experiment are discussed.",
        "positive": "Deep Learning for Automated Experimentation in Scanning Transmission\n  Electron Microscopy: Machine learning (ML) has become critical for post-acquisition data analysis\nin (scanning) transmission electron microscopy, (S)TEM, imaging and\nspectroscopy. An emerging trend is the transition to real-time analysis and\nclosed-loop microscope operation. The effective use of ML in electron\nmicroscopy now requires the development of strategies for microscopy-centered\nexperiment workflow design and optimization. Here, we discuss the associated\nchallenges with the transition to active ML, including sequential data analysis\nand out-of-distribution drift effects, the requirements for the edge operation,\nlocal and cloud data storage, and theory in the loop operations. Specifically,\nwe discuss the relative contributions of human scientists and ML agents in the\nideation, orchestration, and execution of experimental workflows and the need\nto develop universal hyper languages that can apply across multiple platforms.\nThese considerations will collectively inform the operationalization of ML in\nnext-generation experimentation."
    },
    {
        "anchor": "Nature of proton transport in a water-filled carbon nanotube and in\n  liquid water: Proton transport (PT) in bulk liquid water and within a thin water-filled\ncarbon nanotube has been examined with ab initio pathintegral molecular\ndynamics (PIMD). Barrierless proton transfer is observed in each case when\nquantum nuclear effects (QNEs) are accounted for. The key difference between\nthe two systems is that in the nanotube facile PT is facilitated by a favorable\nprealignment of water molecules, whereas in bulk liquid water solvent\nreorganization is required prior to PT. Configurations where the quantum excess\nproton is delocalized over several adjacent water molecules along with\ncontinuous interconversion between different hydration states reveals that, as\nin liquid water, the hydrated proton under confinement is best described as a\nfluxional defect, rather than any individual idealized hydration state such as\nZundel, Eigen, or the so-called linear H7O3+ complex along the water chain.\nThese findings highlight the importance of QNEs in intermediate strength\nhydrogen bonds (HBs) and explain why H+ diffusion through nanochannels is\nimpeded much less than other cations.",
        "positive": "Defect calculations in semiconductors through a dielectric-dependent\n  hybrid DFT functional: the case of oxygen vacancies in metal oxides: We investigate the behavior of oxygen vacancies in three different\nmetal-oxide semiconductors (rutile and anatase TiO2, monoclinic WO3, and\ntetragonal ZrO2) using a recently proposed hybrid density-functional method in\nwhich the fraction of exact exchange is material-dependent but obtained ab\ninitio in a self-consistent scheme. In particular, we calculate\ncharge-transition levels relative to the oxygen-vacancy defect and compare\ncomputed optical and thermal excitation/emission energies with the available\nexperimental results, shedding light on the underlying excitation mechanisms\nand related materials properties. We find that this novel approach is able to\nreproduce not only ground-state properties and band structures of perfect bulk\noxide materials, but also provides results consistent with the optical and\nelectrical behavior observed in the corresponding substoichiometric defective\nsystems."
    },
    {
        "anchor": "Influence of Structural Defects on Charge Density Waves in 1T-TaS2: The influence of intrinsic defects of 1T-TaS2 on charge density waves (CDW)\nis studied using scanning tunneling microscopy and spectroscopy (STM, STS),\nangle-resolved photoelectron spectroscopy (ARPES), and density functional\ntheory (DFT). We identify several types of structural defects and find that\nmost have a local character limited to the single CDW site, with single\nexception which effectively behaves as a dopant, leading to band bending and\naffecting multiple neighboring sites. While only one type of defect can be\nobserved by STM topographic imaging, all defects are easily resolved by local\ndensity of states (LDOS) mapping with STS. We correlate atomically-resolved STM\nperiodicity of defect-free 1T-TaS2 to top sulfur atoms and introduce tiling of\nthe surface using equiangular hexagon. DFT calculations (with included Coulomb\ninteractions) are used to investigate the electronic structure by introducing\nsulfur vacancy or substituting sulfur with oxygen. The sulfur vacancy is\ncharacterized by metallic properties and is identified as an origin of one of\nobserved experimentally defects. Whereas in the case of the latter, the\noxidation of 1T-TaS2 is found to result in the loss of magnetic properties\nexpected in defect-free material.",
        "positive": "Assessing size effects on the deformation of nanovoids in metallic\n  materials: An experimental methodology is developed to evaluate size effects in\nnanovoids deformation under macroscopic uniaxial stress loading conditions.\nQuantitative evaluation of voids deformation as a function of voids size shows\nboth a crystallographic effect, albeit small compared to the scatter, and no\nevidence of size effects for voids diameter larger than 10 nm, while a slight\neffect is present for smaller voids. Critical assessment of the data in light\nof theoretical models indicates that these results may be compatible with the\npresence of a hardened layer at the void/matrix interface, which is illustrated\nthrough finite element simulations accounting for surface tension."
    },
    {
        "anchor": "Aluminum depletion induced by complex co-segregation of carbon and boron\n  in a \u03a3 5 [3 1 0] bcc-iron grain boundary: The local variation of grain boundary atomic structure and chemistry caused\nby segregation of impurities influences the macroscopic properties of\npoylcrystalline materials. Here, the effect of co-segregation of carbon and\nboron on the depletion of aluminum at a $\\Sigma 5\\,(3\\,1\\,0\\,) [0\\,0\\,1]$ tilt\ngrain boundary in a $\\alpha-$Fe-$4~at.~\\%$Al bicrystal was studied by combining\natomic resolution scanning transmission electron microscopy, atom probe\ntomography and density functional theory calculations. The atomic grain\nboundary structural units mostly resemble kite-type motifs and the structure\nappears disrupted by atomic scale defects. Atom probe tomography reveals that\ncarbon and boron impurities are co-segregating to the grain boundary reaching\nlevels of >1.5 at.\\%, whereas aluminum is locally depleted by approx. 2~at.\\%.\nFirst-principles calculations indicate that carbon and boron exhibit the\nstrongest segregation tendency and their repulsive interaction with aluminum\npromotes its depletion from the grain boundary. It is also predicted that\nsubstitutional segregation of boron atoms may contribute to local distortions\nof the kite-type structural units. These results suggest that the\nco-segregation and interaction of interstitial impurities with substitutional\nsolutes strongly influences grain boundary composition and with this the\nproperties of the interface.",
        "positive": "Quantitative theory of magnetic interactions in solids: In this report we review the method of explicit calculations of interatomic\nexchange interactions of magnetic materials. This involves exchange mechanisms\nnormally referred to as Heisenberg exchange, Dzyaloshinskii-Moriya interaction\nand anisotropic symmetric exchange. The connection between microscopic theories\nof the electronic structure, such as density functional theory or dynamical\nmean field theory, and interatomic exchange, is given in detail. The different\naspects of extracting information for an effective spin Hamiltonian that\ninvolves thousands of atoms, from electronic structure calculations considering\nsignificantly fewer atoms (1-50) is highlighted. Examples of exchange\ninteractions of a large group of materials is presented, which involves heavy\nelements of the 3d period, alloys between transition metals, Heusler compounds,\nmultilayer systems as well as overlayers and adatoms on a substrate, transition\nmetal oxides, 4f elements, magnetic materials in two dimensions and molecular\nmagnets. Where possible, a comparison to experimental data is made, that\nnaturally becomes focused on the magnon dispersion. The influence of relativity\nis reviewed for a few cases, as is the importance of dynamical correlations.\nDevelopment to theories that handle out of equilibrium conditions is also\ndescribed here. The review ends with a short description of extensions of the\ntheories behind explicit calculations of interatomic exchange, to non-magnetic\nsituations, e.g. that describe chemical (charge) order and superconductivity."
    },
    {
        "anchor": "Interatomic forces for transition metals including magnetism: }We present a formalism for extending the second moment tight-binding model,\nincorporating ferro- and anti-ferromagn etic interaction terms which are needed\nfor the FeCr system. For antiferromagnetic and paramagnetic materials, an\nexplicit additional variable representing the spin is required. In a mean-field\napproximation this spin can be eliminated, and the potential becomes explicitly\ntemperature dependent. For ferromagnetic interactions, this degree of freedom\ncan be eliminated, and the formalism reduces to the embedded atom method (EAM)\nand we show the equivale nce of existing EAM potentials to \"magnetic\"\npotentials.",
        "positive": "How to distinguish squeezed and coherent phonons in femtosecond x-ray\n  diffuse scattering: Impulsive optical excitation can generate both coherent and squeezed phonons.\nThe expectation value of the phonon displacement $<u_q>$ oscillates at the mode\nfrequency for the coherent state but remains zero for a pure squeezed state. In\ncontrast, both show oscillations in $<|u_q|^2>$ at twice the mode frequency.\nTherefore it can be difficult to distinguish them in a second-order measurement\nof the displacements, such as in first-order x-ray diffuse scattering. Here we\ndemonstrate a simple method to distinguish squeezed from coherent atomic motion\nby measurement of the diffuse scattering following double impulsive excitation.\nWe find that femtosecond optical excitation generates squeezed phonons spanning\nthe Brillouin zone in Ge, GaAs and InSb. Our results confirm the mechanism\nsuggested in [Nature Physics 9, 790 (2013)]."
    },
    {
        "anchor": "Single Crystalline Silver Films for Plasmonics: From Monolayer to\n  Optically Thick Film: Epitaxial growth of single crystalline noble metals on dielectric substrates\nhas received tremendous attention recently due to their technological\npotentials as low loss plasmonic materials. Currently there are two different\ngrowth approaches, each with its strengths and weaknesses. One adopts a\nsophisticated molecular beam epitaxial procedure to grow atomically smooth\nepitaxial Ag films. However, the procedure is rather slow and becomes\nimpractical to grow films with thickness > 50 nm. Another approach adopts a\ngrowth process using rapid e-beam deposition which is capable of growing single\ncrystalline Ag films in the thick regime (> 300 nm). However, the rapid growth\nprocedure makes it difficult to control film thickness precisely, i.e., the\nmethod is not applicable to growing thin epitaxial films. Here we report a\nuniversal approach to grow atomically smooth epitaxial Ag films with precise\nthickness control from a few monolayers to the optically thick regime,\novercoming the limitations of the two aforementioned methods. In addition, we\ndevelop an in-situ growth of aluminum oxide as the capping layer which exhibits\nexcellent properties protecting the epitaxial Ag films. The performance of the\nepitaxial Ag films as a function of the film thickness is investigated by\ndirectly measuring the propagation length of the surface plasmon polaritons\n(SPPs) as well as their device performance to support a waveguide plasmonic\nnanolaser in infrared incorporating an InGaAsP quantum well as the gain media.",
        "positive": "A unified electrostatic and cavitation model for first-principles\n  molecular dynamics in solution: The electrostatic continuum solvent model developed by Fattebert and Gygi is\ncombined with a first-principles formulation of the cavitation energy based on\na natural quantum-mechanical definition for the surface of a solute. Despite\nits simplicity, the cavitation contribution calculated by this approach is\nfound to be in remarkable agreement with that obtained by more complex\nalgorithms relying on a large set of parameters. Our model allows for very\nefficient Car-Parrinello simulations of finite or extended systems in solution,\nand demonstrates a level of accuracy as good as that of established\nquantum-chemistry continuum solvent methods. We apply this approach to the\nstudy of tetracyanoethylene dimers in dichloromethane, providing valuable\nstructural and dynamical insights on the dimerization phenomenon."
    },
    {
        "anchor": "Electronic and energetic properties of Ge(110) pentagons: The electronic and energetic properties of the elementary building block,\ni.e. a five-membered atom ring (pentagon), of the Ge(110) surface was studied\nby scanning tunneling microscopy and spectroscopy at room temperature. The\nGe(110) surface is composed of three types of domains: two ordered domains\n((16x2) and c(8x10)) and a disordered domain. The elementary building block of\nall three domains is a pentagon. Scanning tunneling spectra recorded on the\n(16x2), c(8x10) and disordered domains are very similar and reveal three\nwell-defined electronic states. Two electronic states are located 1.1 eV and\n0.3 eV below the Fermi level respectively, whereas the third electronic state\nis located 0.4 eV above the Fermi level. The electronic states at -0.3 eV and\n0.4 eV can be ascribed to the pentagons, whilst we tentatively assigned the\nelectronic state at -1.1 eV to a Ge-Ge back bond or trough state. In addition,\nwe have analyzed the straight [1-12] oriented step edges. From the kink density\nand kink-kink distance distributions we extracted the nearest neighbor\ninteraction energy between the pentagons, which exhibit a strong preference to\noccur in twins, as well as the strain relaxation energy along the pentagon-twin\nchains.",
        "positive": "Wannier-based definition of layer polarizations in perovskite\n  superlattices: In insulators, the method of Marzari and Vanderbilt [Phys. Rev. B {\\bf 56},\n12847 (1997)] can be used to generate maximally localized Wannier functions\nwhose centers are related to the electronic polarization. In the case of\nlayered insulators, this approach can be adapted to provide a natural\ndefinition of the local polarization associated with each layer, based on the\nlocations of the nuclear charges and one-dimensional Wannier centers comprising\neach layer. Here, we use this approach to compute and analyze layer\npolarizations of ferroelectric perovskite superlattices, including changes in\nlayer polarizations induced by sublattice displacements (i.e., layer-decomposed\nBorn effective charges) and local symmetry breaking at the interfaces. The\nmethod provides a powerful tool for analyzing the polarization-related\nproperties of complex layered oxide systems."
    },
    {
        "anchor": "Electrocrystallization of Supercooled Water Confined between Graphene\n  Layers: A key feature of the crystallization of supercooled water confined in an\napplied static electric field is that the structural order here is determined\nnot only by usual thermodynamic and kinematic factors (degree of supercooling,\ndifference between chemical potentials for a liquid and a crystal, and\nviscosity) but also by the strength and direction of the applied electric\nfield, size of a system (size effects), and the geometry of bounding surfaces.\nIn this work, the electrocrystallization of supercooled water confined between\nideally flat parallel graphene sheets at a temperature of $T=268$~K has been\nconsidered in this work. It has been established that structural order is\ndetermined by two characteristic modes. The initial mode correlates with the\norientation of dipolar water molecules by the applied electric field. The\nsubsequent mode is characterized by the relaxation of a metastable system to a\ncrystalline phase. The uniform electric field applied perpendicularly to the\ngraphene sheets suppresses structural ordering, whereas the field applied in\nthe lateral direction promotes cubic ice $I_c$.",
        "positive": "Low-field microwave absorption and magnetoresistance in iron\n  nanostructures grown by electrodeposition on n-type lightly-doped silicon\n  substrates: In this study we investigate magnetic properties, surface morphology and\ncrystal structure in iron nanoclusters electrodeposited on lightly-doped (100)\nn-type silicon substrates. Our goal is to investigate the spin injection and\ndetection in the Fe/Si lateral structures. The samples obtained under electric\npercolation were characterized by magnetoresistive and magnetic resonance\nmeasurements with cycling the sweeping applied field in order to understand the\nspin dynamics in the as-produced samples. The observed hysteresis in the\nmagnetic resonance spectra, plus the presence of a broad peak in the\nnon-saturated regime confirming the low field microwave absorption (LFMA), were\ncorrelated to the peaks and slopes found in the magnetoresistance curves. The\nresults suggest long range spin injection and detection in low resistive\nsilicon and the magnetic resonance technique is herein introduced as a\npromising tool for analysis of electric contactless magnetoresistive samples."
    },
    {
        "anchor": "Metal-bonded Atomic Layers of Transition Metal Carbides (MXenes): Although two-dimensional transition metal carbides and nitrides (MXenes) have\nfantastic physical and chemical properties as well as wide applications, it\nremains challenging to produce stable MXenes due to their rapid structural\ndegradation. Here, unique metal-bonded atomic layers of transition metal\ncarbides with high stabilities are produced via a simple topological reaction\nbetween chlorine-terminated MXenes and selected metals, where the metals enable\nto not only remove Cl terminations, but also efficiently bond with adjacent\natomic MXene slabs, driven by the symmetry of MAX phases. The films constructed\nfrom Al-bonded Ti$_3$C$_2$Cl$_x$ atomic layers show high oxidation resistance\nup to 400 degrees centigrade and low sheet resistance of 9.3 ohm per square.\nCoupled to the multi-layer structure, the Al-bonded Ti$_3$C$_2$Cl$_x$ film\ndisplays a significantly improved EMI shielding capability with a total\nshielding effectiveness value of 39 dB at a low thickness of 3.1 micron,\noutperforming pure Ti$_3$C$_2$Cl$_x$ film.",
        "positive": "Plastic Response of a 2D Lennard-Jones amorphous solid: Detailed\n  analysis of the local rearrangements at very slow strain-rate: We analyze in details the atomistic response of a model amorphous material\nsubmitted to plastic shear in the athermal, quasistatic limit. After a linear\nstress-strain behavior, the system undergoes a noisy plastic flow. We show that\nthe plastic flow is spatially heterogeneous. Two kinds of plastic events occur\nin the system: quadrupolar localized rearrangements, and shear bands. The\nanalysis of the individual motion of a particle shows also two regimes: a\nhyper-diffusive regime followed by a diffusive regime, even at zero\ntemperature."
    },
    {
        "anchor": "Size dependent crush analysis of lithium orthosilicate pebbles: Crushing strength of the breeder materials (lithium orthosilicate,\n$\\rm{Li_4SiO_4}$ or OSi) in the form of pebbles to be used for EU solid breeder\nconcept is investigated. The pebbles are fabricated using a melt-spray method\nand hence a size variation in the pebbles produced is expected. The knowledge\nof the mechanical integrity (crush strength) of the pebbles is important for a\nsuccessful design of breeder blanket. In this paper, we present the\nexperimental results of the crush (failure) loads for spherical OSi pebbles of\ndifferent diameters ranging from $250~\\mu$m to $800~\\mu$m. The ultimate failure\nload for each size shows a Weibull distribution. Furthermore, the mean crush\nload increases with increase in pebble diameter. It is also observed that the\nlevel of opacity of the pebble influences the crush load significantly. The\nexperimental data presented in this paper and the associated analysis could\npossibly help us to develop a framework for simulating a crushable polydisperse\npebble assembly using discrete element method.",
        "positive": "Dipolar interactions in arrays of ferromagnetic nanowires: a\n  micromagnetic study: We explore the behavior of periodic arrays of magnetic nanowires by\nmicromagnetic simulations using the Nmag modeling package. A large number of\nmodeling studies on such arrays of nanowires have been performed using finite\nsize models. We show that these finite size micromagnetic descriptions can only\nbe used in specific situations. We perform a systematic study of more or less\ndense 1D and 2D arrays of nanowires using either finite size or infinite size\nmodels and we show that finite size models fail to capture some of the features\nof real infinite systems. We show that that the mean field model scaled to the\nsystem porosity is valid. This work can be used as a basis to the extension of\nmicromagnetic calculations of the magnetization dynamics in arrays of\nnanowires."
    },
    {
        "anchor": "Thermo-magnetic characterization of phase transitions in a Ni-Mn-In\n  metamagnetic shape memory alloy: The partially overlapped ferroelastic/martensitic and para-ferromagnetic\nphase transitions of a Ni$_{50.53}$Mn${33.65}$In$_{15.82}$ metamagnetic shape\nmemory alloy have been studied from calorimetric, magnetic and acoustic\nemission measurement. We have taken advantage of the existence of thermal\nhysteresis of the first order ferroelastic/martensitic phase transition\n($\\sim2.5$K) to discriminate the latent heat contribution $\\Delta$Ht = 7.21(15)\nkJ/kg and the specific heat contribution $\\Delta$Hc = 216(1) J/kg to the total\nexcess enthalpy of the phase transition. The specific heat was found to follow\na step-like behavior at this phase transition. The intermittent dynamics of the\nferroelastic/martensitic transition has been characterized as a series of\navalanches detected both from acoustic emission and calorimetric measurements.\nThe energy distribution of these avalanche events was found to follow a power\nlaw with a characteristic energy exponent $\\epsilon\\sim2$ which is in agreement\nwith the expected value for a system undergoing a symmetry change from cubic to\nmonoclinic. Finally, the critical behavior of the para-ferromagnetic austenite\nphase transition that takes place at $\\sim 311$K has been studied from the\nbehavior of the specific heat. A critical exponent $\\alpha\\sim0.09$ has been\nobtained, which has been shown to be in agreement with previous values reported\nfor Ni-Mn-Ga alloys but different from the critical divergence reported for\npure Ni.",
        "positive": "Dynamic Tilting of Ferroelectric Domain Walls via Optically Induced\n  Electronic Screening: Optical excitation perturbs the balance of phenomena selecting the tilt\norientation of domain walls within ferroelectric thin films. The high carrier\ndensity induced in a low-strain BaTiO3 thin film by an above-bandgap ultrafast\noptical pulse changes the tilt angle that 90{\\deg} a/c domain walls form with\nrespect to the substrate-film interface. The dynamics of the changes are\napparent in time-resolved synchrotron x-ray scattering studies of the domain\ndiffuse scattering. Tilting occurs at 298 K, a temperature at which the a/b and\na/c domain phases coexist but is absent at 343 K in the better ordered\nsingle-phase a/c regime. Phase coexistence at 298 K leads to increased\ndomain-wall charge density, and thus a larger screening effect than in the\nsingle-phase regime. The screening mechanism points to new directions for the\nmanipulation of nanoscale ferroelectricity."
    },
    {
        "anchor": "Wide temperature span of entropy change in first-order metamagnetic\n  MnCo1-xFexSi: The crystal structure and magnetic properties of MnCoxFe1-xSi (x=0-0.5)\ncompounds were investigated. With increasing Fe content, the unit cell changes\nanisotropically and the magnetic property evolves gradually: Curie temperature\ndecreases continuously, the first-order metamagnetic transition from a\nlow-temperature helical antiferromagnetic state to a high-temperature\nferromagnetic state disappears gradually and then a spin-glass-like state and\nanother antiferromagnetic state emerge in the low temperature region. The Curie\ntransition leads to a moderate conventional entropy change. The metamagnetic\ntransition not only yields a larger negative magnetocaloric effect at lower\napplied fields than in MnCoSi but also produces a very large temperature span\n(103 K for H=5 T) of delta S(T), which results in a large refrigerant capacity.\nThese phenomena were explained in terms of crystal structure change and\nmagnetoelastic coupling mechanism. The low-cost MnCo1-xFexSi compounds are\npromising candidates for near room temperature magnetic refrigeration\napplications because of the large isothermal entropy change and the wide\nworking temperature span.",
        "positive": "Observation of bright and dark exciton transitions in monolayer MoSe2 by\n  photocurrent spectroscopy: We investigate the excitonic transitions in single- and few-layer MoSe2\nphototransistors by photocurrent spectroscopy. The measured spectral profiles\nshow a well-defined peak at the optically active (bright) A0 exciton resonance.\nMore interestingly, when a gate voltage is applied to the MoSe2 to bring its\nFermi level near the bottom of the conduction band, another prominent peak\nemerges at an energy 30 meV above the A0 exciton. We attribute this second peak\nto a gate-induced activation of the spin-forbidden dark exciton transition,\nAD0. Additionally, we evaluate the thickness-dependent optical bandgap of the\nfabricated MoSe2 crystals by characterizing their absorption edge."
    },
    {
        "anchor": "A non-local model for the description of twinning in polycrystalline\n  materials in the context of infinitesimal strains: application to a magnesium\n  alloy: A polycrystalline plasticity model, which incorporates the contribution of\ndeformation twinning, is proposed. For this purpose, each material point is\ntreated as a composite material consisting of a parent constituent and multiple\ntwin variants. In the constitutive equations, the twin volume fractions and\ntheir spatial gradients are treated as external state variables to account for\nthe contribution of twin boundaries to free energy. The set of constitutive\nrelations is implemented in a spectral solver, which allows solving the\ndifferential equations resulting from equilibrium and compatibility conditions.\nThe proposed model is then used to investigate the behavior of a AZ31 magnesium\nalloy. For the investigated loading conditions, the mechanical behavior is\ncontrolled by the joint contribution of basal slip and tensile twinning. Also,\naccording to the numerical results, the development of crystallographic\ntexture, morphological texture and internal stresses is consistent with the\nexperimental observations of the literature.",
        "positive": "Adsorption, self-assembly and self-metalation of tetra-cyanophenyl\n  porphyrins on semiconducting CoO(100) films: The adsorption properties of free base\n5,10,15,20-tetrakis(p-cyanophenyl)porphyrin (2H-TCNPP) on thin films of rock\nsalt (rs) CoO(100) on Au(111) was studied in ultra-high vacuum by a combination\nof low-temperature scanning tunneling microscopy and spectroscopy (STM/STS) and\ndensity functional theory (DFT). Films of rs-CoO(100) on Au(111) are prepared\nwith excellent quality in a suitable thickness range. Particularly, we found\nthat films of only 1 nm thickness show a semiconducting energy gap of\n$E_\\mathrm{g}=(2.5\\pm 0.2)\\,\\textrm{eV}$. Upon deposition at 300 K, 2H-TCNPP\nadsorbs flat-lying and self-assembles in a long-range ordered superstructure\nthat is stable at 80 K. The adsorption geometry of the molecules on the surface\nand within the self-assembly is analyzed by DFT. We find that the\nself-assemblies are stabilized by hydrogen bridge bonding via the functional\ncyano groups. Our STS data shows molecular states within the fundamental gap of\nthe CoO. By comparison with the calculated DOS we determine the energetic\npositions of the frontier orbitals and find that the first three LUMO states\n2H-TCNPP are located within the band gap, whereas the HOMO is shifted 1 eV\nbelow the CoO conduction band edge. Upon annealing to 420 K the molecules\nchange their appearance in STM images and a new prominent electronic state\nlocated at the center of the molecule is formed. We interpret this changed\nconfiguration as Co-TCNPP created by self-metalation on the oxide surface."
    },
    {
        "anchor": "Giant spin-orbit torque efficiency in all-epitaxial heterostructures: A large anti-damping spin-obit torque (SOT) efficiency in magnetic\nheterostructures is a prerequisite to realize energy efficient spin torque\nbased magnetic memories and logic devices. The efficiency can be characterized\nin terms of the spin-orbit fields generated by anti-damping torques when an\nelectric current is passed through the non-magnetic layer. We report a giant\nspin-orbit field of 48.96 (27.50) mT at an applied current density of 1 MAcm-2\nin beta-W interfaced Co60Fe40 (Ni81Fe19)/TiN epitaxial structures due to an\nanti-damping like torque, which results in a magnetization auto-oscillation\ncurrent density as low as 1.68(3.27) MAcm-2. The spin-orbit field value\nincreases with decrease of beta-W layer thickness, which affirms that epitaxial\nsurface states are responsible for the extraordinary large efficiency. SOT\ninduced energy efficient in-plane magnetization switching in large 20x100 um2\nstructures has been demonstrated by Kerr microscopy and the findings are\nsupported by results from micromagnetic simulations. The observed giant SOT\nefficiencies in the studied all-epitaxial heterostructures are comparable to\nvalues reported for topological insulators. These results confirm that by\nutilizing epitaxial material combinations an extraordinary large SOT efficiency\ncan be achieved using semiconducting industry compatible 5d heavy metals, which\nprovides immediate solutions for the realization of energy efficient spin-logic\ndevices.",
        "positive": "Theory of magnon-driven spin Seebeck effect: The spin Seebeck effect is a spin-motive force generated by a temperature\ngradient in a ferromagnet that can be detected via normal metal contacts\nthrough the inverse spin Hall effect [K. Uchida {\\it et al.}, Nature {\\bf 455},\n778-781 (2008)]. We explain this effect by spin pumping at the contact that is\nproportional to the spin-mixing conductance of the interface, the inverse of a\ntemperature-dependent magnetic coherence volume, and the difference between the\nmagnon temperature in the ferromagnet and the electron temperature in the\nnormal metal [D. J. Sanders and D. Walton, Phys. Rev. B {\\bf 15}, 1489 (1977)]."
    },
    {
        "anchor": "High temperature in situ SEM assessment followed by ex situ AFM and EBSD\n  investigation of the nucleation and early growth stages of Fe-Al\n  intermetallics: A dedicated in situ heating setup in a scanning electron microscope (SEM)\nfollowed by an ex situ atomic force microscopy (AFM) and electron backscatter\ndiffraction (EBSD) is used to characterize the nucleation and early growth\nstages of Fe-Al intermetallics (IMs) at 596 {\\deg}C. A location tracking is\nused to interpret further characterization. Ex situ AFM observations reveal a\nslight shrinkage and out of plane protrusion of the IM at the onset of IM\nnucleation followed by directional growth. The formed interfacial IM compounds\nwere identified by ex situ EBSD. It is now clearly demonstrated that the\n{\\theta}-phase nucleates first prior to the diffusion-controlled growth of the\n{\\eta}-phase. The {\\theta}-phase prevails the intermetallic layer.",
        "positive": "Direct observation and consequences of dopant segregation inside and\n  outside dislocation cores in perovskite BaSnO3: Distinct dopant behaviors inside and outside dislocation cores are identified\nby atomic-resolution electron microscopy in perovskite BaSnO3 with considerable\nconsequences on local atomic and electronic structures. Driven by elastic\nstrain, when A-site designated La dopants segregate near a dislocation core,\nthe dopant atoms accumulate at the Ba sites in compressively strained regions.\nThis triggers formation of Ba-vacancies adjacent to the core atomic sites\nresulting in reconstruction of the core. Notwithstanding the presence of\nextremely large tensile strain fields, when La atoms segregate inside the\ndislocation core, they become B-site dopants, replacing Sn atoms and\ncompensating the positive charge of the core oxygen vacancies. Electron\nenergy-loss spectroscopy shows that the local electronic structure of these\ndislocations changes dramatically due to the segregation of the dopants inside\nand around the core ranging from formation of strong La-O hybridized electronic\nstates near the conduction band minimum to insulator-to-metal transition."
    },
    {
        "anchor": "Quantum Capacitance Spectroscopy of Single Nanotube Molecules: some errors in equations",
        "positive": "Thermal Transfer in Amorphous Superionic Systems: Using direct atomic simulations, the vibration scattering time scales are\ncharacterized, and then the nature and the quantitative weight of thermal\nexcitations are investigated in an example system Li2S from its amorphous solid\nstate to its partial-solid partial-liquid and, liquid states. For the amorphous\nsolid state at 300 K, the vibration scattering time ranges a few femtoseconds\nto several picoseconds. As a result, both the progagons and diffusons are the\nmain heat carriers and contribute largely to the total thermal conductivity.\nThe enhancement of scattering among vibrations and between vibrations and free\nions flow due to the increase of temperature, will lead to a large reduction of\nthe scattering time scale and the acoustic vibrational thermal conductivity,\ni.e., 0.8 W/mK at 300 K to 0.56 W/mK in the partial solid partial liquid Li2S\nat 700 K. In this latter state, the thermal conductivity contributed by\nconvection increases to the half of the total, as a result of the usually\nneglected cross-correlation between the virial term and the free ions' flow.\nThe vibrational scattering time can be as large as ~ 1.5 picoseconds yet, and\nthe vibrational conductivity is reduced to a still significant 0.42 W/mK\nhighlighting the unexpected role of acoustic transverse and longitudinal\nvibrations in liquid Li2S at 1100 K. At this same temperature, the convection\nheat transfer takes overreaching 0.63 W/mK. Our study provides a fundamental\nunderstanding of the thermal excitations at play in amorphous materials from\nsolid to liquid."
    },
    {
        "anchor": "Size and Stoichiometric Dependence of Thermal Conductivities of\n  InxGa1-xN: A Molecular Dynamics Study: The thermal conductivities k of wurtzite InxGa1-xN are investigated using\nequilibrium molecular dynamics (MD) method. The k of InxGa1-xN rapidly declines\nfrom InN (k_InN = 141 W/mK) or GaN (k_GaN = 500 W/mK) to InxGa1-xN, and reaches\na minimum (k_min = 19 W/mK) when x is around 0.5 at 300 K. The mean free path\n(MFP) of InxGa1-xN, ranging from 2 to 5 nm and following the same trend with\nthe k, is extrapolated in our simulation and a parabolic relationship between x\nand MFP is established. We find that the k of InxGa1-xN decreases with\nincreasing temperatures. The evolution of k of InxGa1-xN is also examined by\nprojecting the momentum-energy relationship of phonons from MD trajectories.\nThe phonon dispersion and phonon density of states for InxGa1-xN reflect a\nslightly more flattened dispersive phononic curve of the alloying system.\nDespite an overestimated k than experimental values, our calculated k at 300 K\nagrees well with the results obtained by solving Boltzmann transport equation\nand also has the same stoichiometric trend with the experimental data. Our\nstudy provides the coherent analysis of the effect of thickness, temperature\nand stoichiometric content on the thermal transport of InxGa1-xN which is\nhelpful for the thermal management of InxGa1-xN based devices.",
        "positive": "Influence of sintering temperature on resistivity, magnetoresistance and\n  thermopower of La0.67Ca0.33MnO3: A systematic investigation of La0.67Ca0.33MnO3 manganites has been\nundertaken, mainly to understand the influence of varying crystallite size\n(nanometer range) on electrical resistivity, magnetic susceptibility and\nthermoelectric power. The materials were prepared by the sol-gel method of\nsintering at four different temperatures between 800 and 1100 degrees C. The\nsamples were characterized by X-ray diffraction and data were analyzed using\nRietveld refinement. The metal-insulator transition temperatures (TP) are found\nto increase with increasing sintering temperatures, while the magnetic\ntransition temperatures (TC) decrease. The electrical resistivity and\nthermoelectric power data at low temperatures (T < TP) have been analyzed by\nconsidering various scattering phenomena, while the high temperature (T > TP)\ndata were analyzed with Mott's small polaron hopping conduction mechanisms.\nPACS Codes: 73.50.Lw, 75.47.Gk, 75.47.Lx"
    },
    {
        "anchor": "Large Spin-to-Charge Conversion in Ultrathin Gold-Silicon Multilayers: Investigation of the spin Hall effect in gold has triggered increasing\ninterest over the past decade, since gold combines the properties of a large\nbulk spin diffusion length and strong interfacial spin-orbit coupling. However,\ndiscrepancies between the values of the spin Hall angle of gold reported in the\nliterature have brought into question the microscopic origin of the spin Hall\neffect in Au. Here, we investigate the thickness dependence of the spin-charge\nconversion efficiency in single Au films and ultrathin Au/Si multilayers by\nnon-local transport and spin-torque ferromagnetic resonance measurements. We\nshow that the spin-charge conversion efficiency is strongly enhanced in\nultrathin Au/Si multilayers, reaching exceedingly large values of 0.99 +/- 0.34\nwhen the thickness of the individual Au layers is scaled down to 2 nm. These\nfindings reveal the coexistence of a strong interfacial spin-orbit coupling\neffect which becomes dominant in ultrathin Au, and bulk spin Hall effect with a\nrelatively low bulk spin Hall angle of 0.012 +/- 0.005. Our experimental\nresults suggest the key role of the Rashba-Edelstein effect in the\nspin-to-charge conversion in ultrathin Au.",
        "positive": "Dielectric catastrophe at the Mott and Wigner transitions in a moir\u00e9\n  superlattice: The metal-insulator transition (MIT) driven by electronic correlations is a\nfundamental and challenging problem in condensed-matter physics. Particularly,\nwhether such a transition can be continuous remains open. The emergence of\nsemiconducting moir\\'e materials with continuously tunable bandwidth provides\nan ideal platform to study interaction-driven MITs. Although a bandwidth-tuned\nMIT at fixed full electron filling of the moir\\'e superlattice has been\nreported recently, that at fractional filling, which involves translational\nsymmetry breaking of the underlying superlattice, remains elusive. Here, we\ndemonstrate bandwidth-tuned MITs in a MoSe2/WS2 moir\\'e superlattice at both\ninteger and fractional fillings using the exciton sensing technique. The\nbandwidth is controlled by an out-of-plane electric field. The dielectric\nresponse is probed optically with the 2s exciton in a remote WSe2 sensor layer.\nThe exciton spectral weight is negligible for the metallic state, consistent\nwith a large negative dielectric constant. It continuously vanishes when the\ntransition is approached from the insulating side, corresponding to a diverging\ndielectric constant or a \"dielectric catastrophe\". Our results support\ncontinuous interaction-driven MITs in a two-dimensional triangular lattice and\nstimulate future explorations of exotic quantum phases, such as quantum spin\nliquids, in their vicinities."
    },
    {
        "anchor": "How local is the Phantom Force?: The phantom force is an apparently repulsive force, which can dominate the\natomic contrast of an AFM image when a tunneling current is present. We\ndescribed this effect with a simple resistive model, in which the tunneling\ncurrent causes a voltage drop at the sample area underneath the probe tip.\nBecause tunneling is a highly local process, the areal current density is quite\nhigh, which leads to an appreciable local voltage drop that in turn changes the\nelectrostatic attraction between tip and sample. However, Si(111)-7\\times7 has\na metallic surface-state and it might be proposed that electrons should instead\npropagate along the surface-state, as through a thin metal film on a\nsemiconducting surface, before propagating into the bulk. In this article, we\ninvestigate the role of the metallic surface-state on the phantom force. First,\nwe show that the phantom force can be observed on H/Si(100), a surface without\na metallic surface-state. Furthermore, we investigate the influence of the\nsurface-state on our phantom force observations of Si(111)-7\\times7 by\nanalyzing the influence of the macroscopic tip radius R on the strength of the\nphantom force, where a noticeable effect would be expected if the local voltage\ndrop would reach extensions comparable to the tip radius. We conclude that a\nmetallic surface-state does not suppress the phantom force, but that the local\nresistance Rs has a strong effect on the magnitude of the phantom force.",
        "positive": "Structural Modulation and BC8 Enrichment of Silicon via Dynamic\n  Decompression: The modern very large-scale integration systems based on silicon\nsemiconductor are facing the unprecedented challenges especially when\ntransistor feature size lowers further, due to the excruciating tunneling\neffect and thermal management. Besides the common diamond cubic silicon,\nnumerous exotic silicon allotropes with outstanding properties can emerge under\nhigh pressure, such as the metastable BC8 and metallic \\b{eta}-tin structures.\nDespite much effort on the controlled synthesis in experiment and theory, the\neffective approach to rationally prepare Si phases with desired purity is still\nlacking and their transition mechanism remains controversial. Herein, we\nsystematically investigated on the complicated structural transformations of Si\nunder extreme conditions, and efficiently enriched BC8-Si phase via dynamic\ndecompression strategy. The splendid purity of BC8-Si was achieved up to ~95%,\nevidently confirmed by Raman spectroscopy and synchrotron X-ray diffraction. We\nbelieve these results can shed a light on the controlled preparation of Si\nmetastable phases and their potential applications in nanoelectronics."
    },
    {
        "anchor": "Anomalous Plasticity of Body-Centered-Cubic Crystals with Non-Schmid\n  Effect: Plastic deformations in body-centered-cubic (BCC) crystals have been of\ncritical importance in diverse engineering and manufacturing contexts across\nlength scales. Numerous experiments and atomistic simulations on BCC crystals\nreveal that classical crystal plasticity models with the Schmid law are not\nadequate to account for abnormal plastic deformations often found in these\ncrystals. In this paper, we address a continuum mechanical treatment of\nanomalous plasticity in BCC crystals exhibiting non-Schmid effects, inspired\nfrom atomistic simulations recently reported. Specifically, anomalous features\nof plastic flows are addressed in conjunction with a single crystal\nconstitutive model involving two non-Schmid projection tensors widely accepted\nfor representing non-glide components of an applied stress tensor. Further,\nmodeling results on a representative BCC single crystal (tantalum) are\npresented and compared to experimental data at a range of low temperatures to\nprovide physical insight into deformation mechanisms in these crystals with\nnon-Schmid effects.",
        "positive": "ab inito local vibrational modes of light impurities in silicon: We have developed a formulation of density functional perturbation theory for\nthe calculation of vibrational frequencies in molecules and solids, which uses\nnumerical atomic orbitals as a basis set for the electronic states. The\n(harmonic) dynamical matrix is extracted directly from the first order change\nin the density matrix with respect to infinitesimal atomic displacements from\nthe equilibrium configuration. We have applied this method to study the\nvibrational properties of a number of hydrogen-related complexes and light\nimpurities in silicon. The diagonalization of the dynamical matrix provides the\nvibrational modes and frequencies, including the local vibrational modes (LVMs)\nassociated with the defects. In addition to tests on simple molecules, results\nfor interstitial hydrogen, hydrogen dimers, vacancy-hydrogen and\nself-interstitial-hydrogen complexes, the boron-hydrogen pair, substitutional\nC, and several O-related defects in c-Si are presented. The average error\nrelative to experiment for the aprox.60 predicted LVMs is about 2% with most\nhighly harmonic modes being extremely close and the more anharmonic ones within\n5-6% of the measured values."
    },
    {
        "anchor": "Magnetism in Mn Nanowires and Clusters as \u03b4-doped Layers in Group\n  IV Semiconductors (Si, Ge): Mn doping of group-IV semiconductors (Si/Ge) is achieved by embedding a thin\nMn-film as a {\\delta}-doped layer in group-IV matrix. The Mn-layer consists of\na dense layer of monoatomic Mn-wires, which are oriented perpendicular to the\nSi(001)-(2x1) dimer rows, or Mn-clusters. The nanostructures are covered with\nan amorphous Si or Ge capping layer, which conserves the identity of the\n{\\delta}-doped layer. The analysis of the bonding environment with STM is\ncombined with the element-specific detection of the magnetic signature with\nX-ray magnetic circular dichroism. The largest moment (2.5 {\\mu}B/Mn) is\nmeasured for Mn-wires, which have ionic bonding character, with an a-Ge\noverlayer cap, a-Si capping leads to a slightly reduced moment which has its\norigin in subtle variation of bonding geometry. Our results directly confirm\ntheoretical predictions on magnetism for Mn-adatoms on Si(001). The moment is\nquenched to 0.5{\\mu}B/Mn for {\\delta}-doped layers, which are dominated by\nclusters, and thus develop an antiferromagnetic component from Mn-Mn bonding.",
        "positive": "In-plane Topological p-n Junction in the Three-Dimensional Topological\n  Insulator Bi$_{2-x}$Sb$_x$Te$_{3-y}$Se$_y$: A topological p-n junction (TPNJ) is an important concept to control spin and\ncharge transport on a surface of three dimensional topological insulators\n(3D-TIs). Here we report successful fabrication of such TPNJ on a surface of\n3D-TI Bi$_{2-x}$Sb$_x$Te$_{3-y}$Se$_y$ thin films and experimental observation\nof the electrical transport. By tuning the chemical potential of n-type\ntopological Dirac surface of BSTS on its top half by employing\ntetrafluoro-7,7,8,8-tetracyanoquinodimethane as an organic acceptor molecule, a\nhalf surface can be converted to p-type with leaving the other half side as the\nopposite n-type, and consequently TPNJ can be created. By sweeping the\nback-gate voltage in the field effect transistor structure, the TPNJ was\ncontrolled both on the bottom and the top surfaces. A dramatic change in\nelectrical transport observed at the TPNJ on 3D-TI thin films promises novel\nspin and charge transport of 3D-TIs for future spintronics."
    },
    {
        "anchor": "Electron transport under an ultrafast laser pulse: Implication for spin\n  transport: Laser-driven electron transport across a sample has garnered enormous\nattentions over several decades, because it potentially allows one to control\nspin transports in spintronics. But light is a transverse electromagnetic wave,\nhow an electron acquires a longitudinal velocity has been very puzzling. In\nthis paper, we show a general mechanism is working. It is the magnetic field\n{\\bf B} that steers the electron moving along the light propagation direction,\nwhile its strong transverse motion leads to local excitation. We employ the\nformalism put forth by Varga and Toroke to show that if we only include {\\bf\nE}, the electron only moves transversely with a large velocity. Including both\n{\\bf B} and {\\bf E} and using real experimental laser parameters, we are able\nto demonstrate that a laser pulse can drive the electron along the axial\ndirection by 20 to 262 $\\rm \\AA$, consistent with the experiments. The key\ninsight is that {\\bf B} changes the direction of the electron and allows the\nelectron to move along the Poynting vector of light. Our finding has an\nimportant consequence. Because a nonzero {\\bf B} means a spatially dependent\nvector potential ${\\bf A} (\\br,t)$, ${\\bf B}=\\nabla \\times {\\bf A}(\\br,t)$,\nthis points out that the Coulomb gauge, that is, replacing ${\\bf A}(\\br,t)$ by\na spatial independent ${\\bf A}(t)$, is unable to describe electron and spin\ntransport under laser excitation. Our finding is expected to have a potential\nimpact on the ongoing investigation of laser-driven spin transport.",
        "positive": "Weak Antilocalization Effect up to ~ 120 K in the van der Waals Crystal\n  Fe5-xGeTe2 with Near Room Temperature Ferromagnetism: The weak antilocalization (WAL) effect is known as a quantum correction to\nthe classical conductivity, which never appeared in two-dimensional magnets. In\nthis work, we reported the observation of a WAL effect in the van der Waals\nferromagnet Fe5-xGeTe2 with a Curie temperature Tc ~ 270 K, which can even\nreach as high as ~ 120 K. The WAL effect could be well described by the\nHikami-Larkin-Nagaoka and Maekawa-Fukuyama theories in the presence of strong\nspin-orbit coupling (SOC). Moreover, A crossover from a peak to dip behavior\naround 60 K in both the magnetoresistance and magnetoconductance was observed,\nwhich could be ascribed to a rare example of temperature driven Lifshitz\ntransition as indicated by the angle-resolved photoemission spectroscopy\nmeasurements and first principles calculations. The reflective magnetic\ncircular dichroism measurements indicate a possible spin reorientation that\nkills the WAL effect above 120 K. Our findings present a rare example of WAL\neffect in two-dimensional ferromagnet and also a magnetotransport fingerprint\nof the strong SOC in Fe5-xGeTe2. The results would be instructive for\nunderstanding the interaction Hamiltonian for such high Tc itinerant\nferromagnetism as well as be helpful for the design of next-generation room\ntemperature spintronic or twistronic devices."
    },
    {
        "anchor": "Unsupervised Phase Mapping of X-ray Diffraction Data by Nonnegative\n  Matrix Factorization Integrated with Custom Clustering: Analyzing large X-ray diffraction (XRD) datasets is a key step in\nhigh-throughput mapping of the compositional phase diagrams of combinatorial\nmaterials libraries. Optimizing and automating this task can help accelerate\nthe process of discovery of materials with novel and desirable properties.\nHere, we report a new method for pattern analysis and phase extraction of XRD\ndatasets. The method expands the Nonnegative Matrix Factorization method, which\nhas been used previously to analyze such datasets, by combining it with custom\nclustering and cross-correlation algorithms. This new method is capable of\nrobust determination of the number of basis patterns present in the data which,\nin turn, enables straightforward identification of any possible peak-shifted\npatterns. Peak-shifting arises due to continuous change in the lattice\nconstants as a function of composition, and is ubiquitous in XRD datasets from\ncomposition spread libraries. Successful identification of the peak-shifted\npatterns allows proper quantification and classification of the basis XRD\npatterns, which is necessary in order to decipher the contribution of each\nunique single-phase structure to the multi-phase regions. The process can be\nutilized to determine accurately the compositional phase diagram of a system\nunder study. The presented method is applied to one synthetic and one\nexperimental dataset, and demonstrates robust accuracy and identification\nabilities.",
        "positive": "Quantum phase diagram of high-pressure hydrogen: The interplay between electron correlation and nuclear quantum effects makes\nour understanding of elemental hydrogen a formidable challenge. Here, we\npresent the phase diagram of hydrogen and deuterium at low temperatures and\nhigh-pressure ($P > 300$ GPa by accounting for highly accurate electronic and\nnuclear enthalpies. We evaluated internal electronic energies by diffusion\nquantum Monte Carlo, while nuclear quantum motion and anharmonicity have been\nincluded by the stochastic self-consistent harmonic approximation. Our results\nshow that the long-sought atomic metallic hydrogen, predicted to host\nroom-temperature superconductivity, forms at $577\\pm 10$ GPa ($640\\pm 14$ GPa\nin deuterium). Indeed, anharmonicity pushes the stability of this phase towards\npressures much larger than previous theoretical estimates or attained\nexperimental values. Before atomization, molecular hydrogen transforms from a\nconductive phase III to another metallic structure that is still molecular\n(phase VI) at $422\\pm 40$ GPa ($442\\pm30$ GPa in deuterium). We predict\nclear-cut signatures in optical spectroscopy and DC conductivity that can be\nused experimentally to distinguish between the two structural transitions.\nAccording to our findings, the experimental evidence of metallic hydrogen has\nso far been limited to molecular phases."
    },
    {
        "anchor": "Impurity modes and effect of clustering in diluted semiconductor alloys: The variation of TO zone-center vibration spectra with concentration in mixed\nzincblende-type semiconductors can be understood within a paradigm of unified\n\"one bond - two modes\" approach, which has been recently outlined as a rather\ngeneral concept, and emerges from a number of previous experimental and\ntheoretical studies. The crucial issue is that the vibration frequency,\nassociated with a certain cation-anion bond, depends on the length of the\nlatter, and the bond length, in its turn, depends not only on the average alloy\nconcentration, but on local variations of it. In an (A,B)C substitutional\nalloy, the A-C bond length differ in A-rich and A-poor regions, yielding a\nsplitting of the A-C vibration frequency. Such splittings can be measured and\nreproduced in first-principles calculations.\n  An analysis of vibration spectra helps to get an insight into the structural\nshort-range (clustering) and long-range (formation of extended chains of\ncertain cation-anion pairs and other structural motives at the mesoscopic\nscale) tendencies. For this however, one needs first-principles benchmark\ncalculations for representative model systems. The simplest yet important\nresult from first-principles calculations is a prediction of how the impurity\nphonon mode evolves as isolated (distant) impurities get clustered.",
        "positive": "Loss tangent measurements of dielectric substrates from 15 K to 300 K\n  with two resonators: investigation into accuracy issues: The loss tangent of medium, low and very low loss dielectric substrates\n(including the Rogers RT Duroid 5880 and 6010.2, LaAlO3, (La, Sr)(Al, Ta)O3,\nMgO and Quartz) was measured at varying temperatures with two TE01{\\delta}\ndielectric resonators to ensure verification of the tests. The accuracy of the\nmeasurements has been researched and discussed for split post dielectric\nresonator (SPDR) in a copper enclosure and a single post dielectric resonator\n(SuPDR) in a superconducting enclosure in the temperature range from 15K to 300\nK."
    },
    {
        "anchor": "The role of weakest links and system size scaling in multiscale modeling\n  of stochastic plasticity: Plastic deformation of crystalline and amorphous matter often involves\nintermittent local strain burst events. To understand the physical background\nof the phenomenon a minimal stochastic mesoscopic model was introduced, where\nmicrostructural details are represented by a fluctuating local yielding\nthreshold. In the present paper, we propose a method for determining this yield\nstress distribution by lower scale discrete dislocation dynamics simulations\nand using a weakest link argument. The success of scale-linking is demonstrated\non the stress-strain curves obtained by the resulting mesoscopic and the\ndiscrete dislocation models. As shown by various scaling relations they are\nstatistically equivalent and behave identically in the thermodynamic limit. The\nproposed technique is expected to be applicable for different microstructures\nand amorphous materials, too.",
        "positive": "Machine Learning-Assisted Exploration of Thermally Conductive Polymers\n  Based on High-Throughput Molecular Dynamics Simulations: Finding amorphous polymers with higher thermal conductivity is important, as\nthey are ubiquitous in heat transfer applications. With recent progress in\nmaterial informatics, machine learning approaches have been increasingly\nadopted for finding or designing materials with desired properties. However,\nrelatively limited effort has been put into finding thermally conductive\npolymers using machine learning, mainly due to the lack of polymer thermal\nconductivity databases with reasonable data volume. In this work, we combine\nhigh-throughput molecular dynamics (MD) simulations and machine learning to\nexplore polymers with relatively high thermal conductivity (> 0.300 W/m-K). We\nfirst randomly select 365 polymers from the existing PolyInfo database and\ncalculate their thermal conductivity using MD simulations. The data are then\nemployed to train a machine learning regression model to quantify the\nstructure-thermal conductivity relation, which is further leveraged to screen\npolymer candidates in the PolyInfo database with thermal conductivity > 0.300\nW/m-K. 133 polymers with MD-calculated thermal conductivity above this\nthreshold are eventually identified. Polymers with a wide range of thermal\nconductivity values are selected for re-calculation under different simulation\nconditions, and those polymers found with thermal conductivity above 0.300\nW/m-K are mostly calculated to maintain values above this threshold despite\nfluctuation in the exact values. A classification model is also constructed,\nand similar results were obtained compared to the regression model in\npredicting polymers with thermal conductivity above or below 0.300 W/m-K. The\nstrategy and results from this work may contribute to automating the design of\npolymers with high thermal conductivity."
    },
    {
        "anchor": "Spatially-Modulated Silicon Interface Energetics via Hydrogen\n  Plasma-Assisted Atomic Layer Deposition of Ultrathin Alumina: Atomic layer deposition (ALD) is a key technique for the continued scaling of\nsemiconductor devices, which increasingly relies on reproducible and scalable\nprocesses for interface manipulation of 3D structured surfaces on the atomic\nscale. While ALD allows the synthesis of conformal films at low temperature\nwith utmost control over the thickness, atomically-defined closed coatings and\nsurface modifications are still extremely difficult to achieve because of\nthree-dimensional growth during nucleation. Here, we present a route towards\nsub-nanometer thin and continuous aluminum oxide (AlOx) coatings on silicon\n(Si) substrates for the spatial control of the surface charge density and\ninterface energetics. We use trimethylaluminum (TMA) in combination with remote\nhydrogen plasma instead of a gas-phase oxidant for the transformation of\nsilicon oxide into alumina (AlOx). During the initial ALD cycles, TMA reacts\nwith the surface oxide (SiO2) on silicon until there is a saturation of\nbindings sites, after which the oxygen from the underlying surface oxide is\nconsumed, thereby transforming the silicon oxide into Si capped with AlOx.\nDepending on the number of ALD cycles, the SiO2 can be partially or fully\ntransformed, which we exploit to create sub-nanometer thin and continuous AlOx\nlayers deposited in selected regions defined by lithographic patterning. The\nresulting patterned surfaces are characterized by lateral AlOx/SiO2 interfaces\npossessing step heights as small as 0.3 nm and surface potential steps in\nexcess of 0.4 V. In addition, the introduction of fixed negative charges of $9\n\\times 10^{12}$ cm$^{-2}$ enables modulation of the surface band bending, which\nis relevant to the field-effect passivation of Si and low-impedance charge\ntransfer across contact interfaces.",
        "positive": "Magnetic Structure in Fe/Sm-Co Exchange Spring Bilayers with Intermixed\n  Interfaces: The depth profile of the intrinsic magnetic properties in an Fe/Sm-Co bilayer\nfabricated under nearly optimal spring-magnet conditions was determined by\ncomplementary studies of polarized neutron reflectometry and micromagnetic\nsimulations. We found that at the Fe/Sm-Co interface the magnetic properties\nchange gradually at the length scale of 8 nm. In this intermixed interfacial\nregion, the saturation magnetization and magnetic anisotropy are lower and the\nexchange stiffness is higher than values estimated from the model based on a\nmixture of Fe and Sm-Co phases. Therefore, the intermixed interface yields\nsuperior exchange coupling between the Fe and Sm-Co layers, but at the cost of\naverage magnetization."
    },
    {
        "anchor": "Elemental topological Dirac semimetal: \u03b1-Sn on InSb(111): Three-dimensional (3D) topological Dirac semimetals (TDSs) are rare but\nimportant as a versatile platform for exploring exotic electronic properties\nand topological phase transitions. A quintessential feature of TDSs is 3D Dirac\nfermions associated with bulk electronic states near the Fermi level. Using\nangle-resolved photoemission spectroscopy (ARPES), we have observed such bulk\nDirac cones in epitaxially-grown {\\alpha}-Sn films on InSb(111), the first such\nTDS system realized in an elemental form. First-principles calculations confirm\nthat epitaxial strain is key to the formation of the TDS phase. A phase diagram\nis established that connects the 3D TDS phase through a singular point of a\nzero-gap semimetal phase to a topological insulator (TI) phase. The nature of\nthe Dirac cone crosses over from 3D to 2D as the film thickness is reduced.",
        "positive": "Relative Permittivity in the Electrical Double Layer from Nonlinear\n  Optics: Second harmonic generation (SHG) spectroscopy has been applied to probe the\nfused silica/water interface at pH 7 and the uncharged 11bar02 sapphire/water\ninterface at pH 5.2 in contact with aqueous solutions of NaCl, NaBr, NaI, KCl,\nRbCl, and CsCl as low as several 10 microM. For ionic strengths up to about 0.1\nmM, the SHG responses were observed to increase, reversibly for all salts\nsurveyed, when compared to the condition of zero salt added. Further increases\nin the salt concentration led to monotonic decreases in the SHG response. The\nSHG increases followed by decreases are found to be consistent with recent\nreports of phase interference and phase matching in nonlinear optics. By\nvarying the relative permittivity employed in common mean field theories used\nto describe electrical double layers, and by comparing our results to available\nliterature data, we find that models recapitulating the experimental\nobservations are ones in which 1) the relative permittivity of the diffuse\nlayer is that of bulk water, with other possible values as low as 30, 2) the\nsurface charge density varies with salt concentration, and 3) the charge in the\nStern layer or its thickness vary with salt concentration. We also note that\nthe experimental data exhibit sensitivity depending on whether the salt\nconcentration is increased from low to high values or decreased from high to\nlow values, which, however, is not borne out in the fits, at least within the\ncurrent uncertainties associated with the model point estimates."
    },
    {
        "anchor": "Heat conduction across molecular junctions between nanoparticles: We investigate the problem of heat conduction across a molecular junction\nconnecting two nanoparticles, both in vacuum and in a liquid environment, using\nclassical molecular dynamics simulations. In vacuum, the well-known result of a\nlength independent conductance is recovered; its precise value, however, is\nfound to depend sensitively on the overlap between the vibrational spectrum of\nthe junction and the density of states of the nanoparticles that act as thermal\ncontacts. In a liquid environment, the conductance is constant up to a\ncrossover length, above which a standard Fourier regime is recovered.",
        "positive": "Effects of a tungsten addition on the morphological evolution, spatial\n  correlations, and temporal evolution of a model Ni-Al-Cr superalloy: The effect of adding 2 at.% W to a model Ni-Al-Cr superalloy on the\nmorphological evolution, spatial correlations and temporal evolution of\ng'(L12)-precipitates at 1073 K is studied with scanning electron microscopy and\natomic force microscopy. Adding W yields a larger microhardness, earlier onset\nof spheroidal-to-cuboidal precipitate morphological transition, larger volume\nfraction (from ~20 to 30%), reduction in coarsening kinetics by one third and a\nlarger number density (Nv) of smaller mean radii (<R>) precipitates. The\nkinetics of <R> and interfacial area per unit volume obey t1/3 and t-1/3\nrelationships, respectively, which is consistent with coarsening driven by\ninterfacial energy reduction. The Nv power law dependencies deviate, however,\nfrom model predictions indicating that a stationary-state is not achieved.\nQuantitative analyses with precipitate size distributions, pair correlation\nfunctions, and edge-to-edge interprecipitate distance distributions gives\ninsight into 2D microstructural evolution, including the elastically driven\ntransition from a uniform g'-distribution to one-dimensional <001>-strings to\neventually clustered packs of g'-precipitates in the less densely packed\nNi-Al-Cr alloy."
    },
    {
        "anchor": "Anatomy of ultrafast quantitative magneto-acoustics in freestanding\n  nickel thin films: We revisit the quantitative analysis of the ultrafast magneto-acoustic\nexperiment in a freestanding nickel thin film by Kim and Bigot [1] by applying\nour recently proposed approach of magnetic and acoustic eigenmodes\ndecomposition by Vernik et al. [2]. We show that the application of our\nmodeling to the analysis of time-resolved reflectivity measurements allows for\nthe determination of amplitudes and lifetimes of standing perpendicular\nacoustic phonon resonances with unprecedented accuracy. The acoustic damping is\nfound to scale as $\\propto\\omega^2$ for frequencies up to 80~GHz and the peak\namplitudes reach $10^{-3}$. The experimentally measured magnetization dynamics\nfor different orientations of an external magnetic field agrees well with\nnumerical solutions of magneto-elastically driven magnon harmonic oscillators.\nSymmetry-based selection rules for magnon-phonon interactions predicted by our\nmodeling approach allow for the unambiguous discrimination between spatially\nuniform and non-uniform modes, as confirmed by comparing the resonantly\nenhanced magneto-elastic dynamics simultaneously measured on opposite sides of\nthe film. Moreover, the separation of time scales for (early) rising and (late)\ndecreasing precession amplitudes provide access to magnetic (Gilbert) and\nacoustic damping parameters in a single measurement.",
        "positive": "Computationally Efficient Characterization of Potential Energy Surfaces\n  Based on Fingerprint Distances: An analysis of the network defined by the potential energy minima of\nmulti-atomic systems and their connectivity via reaction pathways that go\nthrough transition states allows to understand important characteristics like\nthermodynamic, dynamic and structural properties. Unfortunately computing the\ntransition states and reaction pathways in addition to the significant\nenergetically low-lying local minima is a computationally demanding task. We\nhere introduce a computationally efficient method that is based on a\ncombination of the minima hopping global optimization method and the insight\nthat uphill barriers tend to increase with increasing structural distances of\nthe educt and product states. This method allows to replace the exact\nconnectivity information and transition state energies with alternative and\napproximate concepts. Without adding any significant additional cost to the\nminima hopping global optimization approach, this method allows to generate an\napproximate network of the minima, their connectivity and a rough measure for\nthe energy needed for their interconversion. This can be used to obtain a first\nqualitative idea on important physical and chemical properties by means of a\ndisconnectivity graph analysis. Besides the physical insight obtained by such\nan analysis, the gained knowledge can be used to make a decision if it is\nworthwhile or not to invest computational resources for an exact computation of\nthe transition states and the reaction pathways. Furthermore it is demonstrated\nthat the here presented method can be used for finding physically reasonable\ninterconversion pathways that are promising input pathways for methods like\ntransition path sampling or discrete path sampling."
    },
    {
        "anchor": "Fabrication, phase formation and microstructure of Ni4Nb2O9 ceramics by\n  using two-stage sintering technique: The potential utilization of two-stage sintering for the production of highly\ndense and pure nickel diniobate (Ni4Nb2O9) ceramics with low firing temperature\nwas demonstrated. Effects of designed sintering conditions on phase formation,\ndensification and microstructure of the ceramics were characterized by X-ray\ndiffraction (XRD), Archimedes method and scanning electron microscopy (SEM),\nrespectively. It has been found that minor phase of columbite NiNb2O6 tended to\nform together with the desired Ni4Nb2O9 phase, depending on sintering\nconditions. The optimization of sintering conditions could lead to a\nsingle-phase Ni4Nb2O9 ceramics with orthorhombic structure. The ceramics doubly\nsintered at 950/1250 {\\deg}C for 4 h exhibited maximum density value of 92%.\nMicrostructures with denser angular grain-packing were generally found in both\nsets of the sintered Ni4Nb2O9 ceramics. However, the grains were irregular in\nshape when the samples are sintered at 1050/1250 {\\deg}C. Two-stage sintering\nwas also found to enhance ferroelectric behavior of Ni4Nb2O9 ceramic.",
        "positive": "Compaction dynamics of metallic nano-foams: A molecular dynamics\n  simulation study: We investigate, by molecular dynamics simulation, the generic features\nassociated with the dynamic compaction of metallic nano-foams at very high\nstrain rates. A universal feature of the dynamic compaction process is revealed\nas composed of two distinct regions: a growing crushed region and a leading\nfluid precursor. The crushed region has a density lower than the solid material\nand gradually grows thicker in time by {\\it snowplowing}. The trapped fluid\nprecursor is created by ablation and/or melting of the foam filaments and the\nsubsequent confinement of the hot atoms in a region comparable to the filament\nlength of the foam. Quantitative characterization of nano-foam compaction\ndynamics is presented and the compacted form equation-of-state is discussed. We\nargue that high-energy foam crushing is not a shock phenomenon even though both\nshare the snowplow feature."
    },
    {
        "anchor": "Phonon-pair-driven Ferroelectricity Causes Costless Domain-walls and\n  Bulk-boundary Duality: Ferroelectric domain walls, recognized as distinct from the bulk in terms of\nsymmetry, structure, and electronic properties, host exotic phenomena including\nconductive walls, ferroelectric vortices, novel topologies, and negative\ncapacitance. Contrary to conventional understanding, our study reveals that the\nstructure of domain walls in HfO2 closely resembles its bulk. First, our\nfirst-principles simulations unveil that the robust ferroelectricity is\nsupported by bosonic pairing of all the anionic phonons in bulk HfO2.\nStrikingly, the paired phonons strongly bond with each other and successfully\nreach the center of the domain wall without losing their integrity and produce\nbulk-like domain walls. We then confirmed preservation of the bulk phonon\ndisplacements and consequently full revival of the bulk structure at domain\nwalls via aberration-corrected STEM. The newly found duality between the bulk\nand the domain wall sheds light on previously enigmatic properties such as\nzero-energy domain walls, perfect Ising-type polar ordering, and exceptionally\nrobust ferroelectricity at the sub-nm scales. The phonon-pairing discovered\nhere is robust against physical boundaries such as domain walls and enables\nzero momentum and zero-energy cost local ferroelectric switching. This\nphenomenon demonstrated in Si-compatible ferroelectrics provides a novel\ntechnological platform where data storage on domain walls is as feasible as\nthat within the domains, thereby expanding the potential for high-density data\nstorage and advanced ferroelectric applications.",
        "positive": "Amorphous VO$_x$ films with high temperature coefficient of the\n  resistivity grown by reactive e-beam evaporation of V metal: Amorphous VO$_x$ films without a hysteretic phase transition are stable with\nrespect to thermal cycling and highly demanded as sensitive elements of the\nresistive thermometers and microbolometers. In this paper we present simple and\nlow-temperature growth of amorphous vanadium oxide films by reactive electron\nbeam evaporation of vanadium metal in $\\sim 10^{-4}$ mBar oxygen atmosphere.\nThe temperature coefficient of the resistivity (TCR) of the films is weakly\nsensitive to substrate material and temperature and could be tuned by oxygen\npressure in the growth chamber up to -2.2\\% /K. The resistivity value is stable\nfor months. It depends on the substrate material and substrate temperature\nduring the evaporation. Simplicity and controllability of the method should\nlead to various laboratory and industrial applications."
    },
    {
        "anchor": "The simplest model of polymer crystal exhibiting polymorphism: Almost all the polymer crystals have several polymorphic modifications. Their\nstructure and existence conditions, as well as transitions between them are not\nunderstood even in the case of the 'model' polymer polyethylene (PE). For\nanalysis of polymorphism in polymer crystals, we consider the simplest possible\nmodel of polymer chain: an extended flat zigzag made of 'united' atoms\n(replacing CH2-groups in PE chain); the united atoms belonging to different\nzigzags interact via Lennard-Jones potential. Analysis of potential of\ninteraction between such zigzags allowed to predict the structure of five\npossible equilibrium lattices in polymer crystal built out of such zigzags.\nMolecular dynamics simulation of the crystal built out of flexible zigzags\nshowed that, depending on model parameters (dimensions of the zigzag and\nequilibrium distance of Lennard-Jones potential), one to three of these\nlattices are stable in bulk at low temperatures. We have determined the model\nparameters at which the existing stable lattices are analogous to the ones\nobserved in real PE and linear alkanes. The triclinic lattice has the lowest\npotential energy, then follows the monoclinic lattice, and the orthorhombic\nlattice has the highest energy, exactly as in full atomic (with hydrogens)\nmolecular dynamics models.",
        "positive": "Zero-OAM laser printing of chiral nanoneedles: Laser irradiation of various materials including metals, polymers and\nsemiconductors with vortex beams was previously shown to twist transiently\nmolten matter providing the direct easy-to-implement way to obtain chiral\nsurface relief. Specifically for metals, this effect was attributed to transfer\nof an optical angular momentum (OAM) carrying by the vortex beam. In this\nLetter, we report the formation of twisted metal nanoneedles on the surface of\nsilver and gold metal films under their irradiation with zero-OAM laser beam\nhaving spiral-shape lateral intensity distribution. Our comparative experiments\nclearly demonstrate, for the first time, that the formation process of chiral\nnanoneedles on the surface of plasmonic-active metals is mainly governed by the\ntemperature-gradient induced chiral thermocapillary mass transfer rather that\nthe OAM driven rotation of the transiently molten matter."
    },
    {
        "anchor": "Instability Mechanism for STT-MRAM switching: To optimize the design of STT-MRAM (spin-transfer torque magnetic random\naccess memory), it is necessary to be able to predict switching (error) rates.\nFor small elements, this can be done using a single-macrospin theory since the\nelement will switch quasi-uniformly. Experimental results on switching rates\nsuggest that elements large enough to be thermally stable switch by some\nmechanism with a lower energy barrier. It has been suggested that this\nmechanism is local nucleation, but we have also previously reported a global\nmagnetostatic instability, which is consistent with the lower experimental\nenergy barriers. In this paper, we try to determine which of these mechanisms\nis most important by visualizing the switching in a \"U-NU\" (uniform -\nnonuniform) phase diagram. We find that switching trajectories follow the\nhorizontal U axis (i.e., quasi-uniform precession) until they reach a critical\namplitude, at which the magnetostatic instability grows exponentially and a\ndomain wall forms at the center, whose motion completes the switching. We have\ntried unsuccessfully to induce local nucleation (a domain wall at the edge). We\nconclude that the dominant switching mechanism is not edge nucleation, but the\nmagnetostatic instability.",
        "positive": "Effects of structure and temperature on the nature of excitons in the\n  Mo0.6W0.4S2 alloys: We have studied the nature of excitons in the transition metal dichalcogenide\nalloy Mo0.6W0.4 S2, compared to pure MoS2 and WS2 grown by atomic layer\ndeposition (ALD). For this, optical absorption/transmission spectroscopy and\ntime-dependent density functional theory (TDDFT) were used. Effects of\ntemperature on the A and B exciton peak energies and linewidths in the optical\ntransmission spectra were compared between the alloy and pure MoS2 and WS2. On\nincreasing the temperature from 25 K to 293 K the energy of the A and B exciton\npeaks decreases, while their linewidth increases due to exciton-phonon\ninteractions. The exciton-phonon interactions in the alloy are closer to those\nfor MoS2 than WS2. This suggests that the exciton wave functions in the alloy\nhave a larger amplitude on Mo atoms than on W atoms. The experimental\nabsorption spectra could be reproduced by TDDFT calculations. Interestingly,\nfor the alloy the Mo and W atoms had to be distributed over all layers.\nConversely, we could not reproduce the experimental alloy spectrum by\ncalculations on a structure with alternating layers, in which every other layer\ncontains only Mo atoms and the layers in between also W atoms. For the latter\natomic arrangement, the TDDFT calculations yielded an additional optical\nabsorption peak that could be due to excitons with some charge transfer\ncharacter. From these results we conclude that ALD yields an alloy in which Mo\nand W atoms are distributed uniformly among all layers."
    },
    {
        "anchor": "Dc-Driven Diatomic Frenkel-Kontorova Model: We investigate the resonance steps, spatiotemporal dynamics, and dynamical\nphase diagrams of the dc-driven diatomic Frenkel-Kontorova model. The complete\nresonance velocity spectrum is given. The diatomic effects result in each\nresonant state being characterized by two integer pairs, $(k_1,k_2)$ and\n$(k_1,k_2^{\\prime})$. In the high-velocity region the linear response of the\naverage velocity, $v$, of the chain to the driving force $F$ is often\npunctuated by subharmonic resonances $(k_1>k_2)$. There are two kinds of\nnonlinear response regions in the high-velocity region. A new physical\ninterpretation of the mean-field treatment is presented.",
        "positive": "Consistent evaluation of continuum scale properties of Graphene: We handshake statistical mechanics with continuum mechanics to develop a\nmethodology for consistent evaluation of the continuum scale properties of\ngraphene. The scope is kept limited to elastic modulus, $E$, which has been\nreported to vary between 0.912 TPa to 7 TPa, Poisson's ratio, $\\nu$, which has\nbeen reported to vary from being negative to a value as large as 0.46, and\neffective thickness, $q$, whose value varies between 0.75 \\AA to 3.41 \\AA. Such\na large scatter arises due to inconsistent evaluation of these properties and\nmaking assumptions that may not be valid at atomistic scales. Our methodology\ncombines three separate methods -- uniaxial tension, equibiaxial tension, and\nflexural out-of-plane free vibrations of simply supported sheets, which, when\nused in tandem in MD, can provide consistent values of $E, \\nu$ and $q$. The\nonly assumption made in the present study is the validity of the continuum\nscale thin plate vibration equation to represent the free vibrations of a long\ngraphene sheet. Our results suggest that -- (i) graphene is auxetic with its\nPoisson's ratio increasing with increasing temperature, (ii) with increasing\ntemperature, $E$ decreases, and (iii) the effective thickness increases with\ntemperature."
    },
    {
        "anchor": "Microscopic Mechanism and Kinetics of Ice Formation at Complex\n  Interfaces: Zooming in on Kaolinite: Most ice in nature forms thanks to impurities which boost the exceedingly low\nnucleation rate of pure supercooled water. However, the microscopic details of\nice nucleation on these substances remain largely unknown. Here, we have\nunraveled the molecular mechanism and the kinetics of ice formation on\nkaolinite, a clay mineral playing a key role in climate science. We find that\nthe formation of ice at strong supercooling in the presence of this clay is\ntwenty orders of magnitude faster than homogeneous freezing. The critical\nnucleus is substantially smaller than that found for homogeneous nucleation\nand, in contrast to the predictions of classical nucleation theory (CNT), it\nhas a strong 2D character. Nonetheless, we show that CNT describes correctly\nthe formation of ice at this complex interface. Kaolinite also promotes the\nexclusive nucleation of hexagonal ice, as opposed to homogeneous freezing where\na mixture of cubic and hexagonal polytypes is observed.",
        "positive": "The interaction of Fe thin layers between MgO(100)-MgO and MgO(100)-Ag\n  surfaces: The atomic interaction and magnetic properties of ultrathin Fe films grown on\ncleaved and polished MgO(100) surfaces were studied by conversion electron\nM\\\"{o}ssbauer spectroscopy (CEMS) in broad temperature range. Fe with different\nlayer thickness was deposited on MgO substrates. The layers were formed on\npolished and cleaved substrate surfaces at RT. The analysis of the spectra\nshowed no Fe-O$^{2-}$ interaction in MgO/Fe interface. Iron layers showed\ndifferent magnetic anisotropy depending on their thickness."
    },
    {
        "anchor": "Heavy Fermion-like metal alpha double prime-Fe16N2 with giant saturation\n  magnetization: A new model is proposed for the strong ferromagnetism associated with\npartially localized orbitals in the Fe16N2 metallic system which draws\nsubstantially from models of heavy fermion metals. We demonstrated that an\nunusual correlation effect is brought up within the Fe-N octahedral cluster\nregion and the effective on-site 3d-3d Coulomb interaction increases due to a\nsubstantial 3d electrons charge density difference between the clusters and its\nsurroundings, which leads to a partially localized high spin electron\nconfiguration with a long range ferromagnetic order. First principle\ncalculation based on LDA+U method shows that giant magnetic moment can be\nachieved at sufficiently large Hubbard U value. The feature of the coexistence\nof the localized and itinerant electron states plays a key role on the\nformation of the giant saturation magnetization.",
        "positive": "Spin-dependent inter- and intra-valley electron-phonon scattering in\n  germanium: We investigate the spin-dependent electron-phonon scatterings of the $L$ and\n$\\Gamma$ valleys and the band structure near the conduction band minima in\ngermanium. We first construct a $16\\times16$ ${\\bm k}\\cdot{\\bm p}$ Hamiltonian\nin the vicinity of the $L$ point in germanium, which ensures the correctness of\nthe band structure of the lowest three conduction bands and highest two valence\nbands. This Hamiltonian facilitates the analysis of the spin-related properties\nof the conduction electrons. We then demonstrate the phonon-induced electron\nscatterings of the $L$ and $\\Gamma$ valleys, i.e., the intra-$\\Gamma$/ $L$\nvalley, inter--$\\Gamma$-$L$ valley and inter--$L$-$L$ valley scatterings in\ngermanium. The selection rules and complete scattering matrices for these\nscatterings are calculated, where the scattering matrices for the\nintra-$\\Gamma$ valley scattering, inter--$\\Gamma$-$L$ valley scattering and the\noptical-phonon and the separated transverse-acoustic- and\nlongitudinal-acoustic-phonon contributions to the intra-$\\Gamma$ valley\nscattering have not been reported in the literature. The coefficients in these\nscattering matrices are obtained via the pseudo-potential calculation, which\nalso verifies our selection rules and wave-vector dependence. We further\ndiscuss the Elliott-Yafet mechanisms in these electron-phonon scatterings with\nthe ${\\bm k}$$\\cdot$${\\bm p}$ eigenstates at the $L$ and $\\Gamma$ valleys. Our\ninvestigation of these electron-phonon scatterings are essential for the study\nof the optical orientation of spin and hot-electron relaxation in germanium."
    },
    {
        "anchor": "Substituting the main group element in cobalt - iron based Heusler\n  alloys: Co$_2$FeAl$_{1-x}$Si$_x$: This work reports about electronic structure calculations for the Heusler\ncompound Co$_2$FeAl$_{1-x}$Si$_x$. Particular emphasis was put on the role of\nthe main group element in this compound. The substitution of Al by Si leads to\nan increase of the number of valence electrons with increasing Si content and\nmay be seen as electron-doping. Self-consistent electronic structure\ncalculations were performed to investigate the consequences of the electron\ndoping for the magnetic properties. The series Co$_2$FeAl$_{1-x}$Si$_x$ is\nfound to exhibit half-metallic ferromagnetism and the magnetic moment follows\nthe Slater-Pauling rule. It is shown that the electron-doping stabilises the\ngap in the minority states for $x=0.5$.",
        "positive": "Molecular Dynamics Prediction of Thermal Conductivity of GaN Films and\n  Wires at Realistic Length Scales: Recent molecular dynamics simulation methods have enabled thermal\nconductivity of bulk materials to be estimated. In these simulations, periodic\nboundary conditions are used to extend the system dimensions to the\nthermodynamic limit. Such a strategy cannot be used for nanostructures with\nfinite dimensions which are typically much larger than it is possible to\nsimulate directly. To bridge the length scales between the simulated and the\nactual nanostructures, we perform large-scale molecular dynamics calculations\nof thermal conductivities at different system dimensions to examine a recently\ndeveloped conductivity vs. dimension scaling theory for both film and wire\nconfigurations. We demonstrate that by an appropriate application of the\nscaling law, reliable interpolations can be used to accurately predict thermal\nconductivity of films and wires as a function of film thickness or wire radius\nat realistic length scales from molecular dynamics simulations. We apply this\nmethod to predict thermal conductivities for GaN wurtzite nanostructures."
    },
    {
        "anchor": "Understanding adsorption of hydrogen atoms on graphene: Adsorption of hydrogen atoms on a single graphite sheet (graphene) has been\ninvestigated by first-principles electronic structure means, employing\nplane-wave based, periodic density functional theory. A reasonably large 5x5\nsurface unit cell has been employed to study single and multiple adsorption of\nH atoms. Binding and barrier energies for sequential sticking have been\ncomputed for a number of configurations involving adsorption on top of carbon\natoms. We find that binding energies per atom range from ~0.8 eV to ~1.9 eV,\nwith barriers to sticking in the range 0.0-0.2 eV. In addition, depending on\nthe number and location of adsorbed hydrogen atoms, we find that magnetic\nstructures may form in which spin density localizes on a\n$\\sqrt{3}{x}\\sqrt{3}{R}30^{\\circ}$ sublattice, and that binding (barrier)\nenergies for sequential adsorption increase (decrease) linearly with the\nsite-integrated magnetization. These results can be rationalized with the help\nof the valence-bond resonance theory of planar $\\pi$ conjugated systems, and\nsuggest that preferential sticking due to barrierless adsorption is limited to\nformation of hydrogen pairs.",
        "positive": "100 GHz Transistors from Wafer Scale Epitaxial Graphene: High-performance graphene field-effect transistors have been fabricated on\nepitaxial graphene synthesized on a two-inch SiC wafer, achieving a cutoff\nfrequency of 100 GHz for a gate length of 240 nm. The high-frequency\nperformance of these epitaxial graphene transistors not only shows the highest\nspeed for any graphene devices up to date, but it also exceeds that of Si\nMOSFETs at the same gate length. The result confirms the high potential of\ngraphene for advanced electronics applications, marking an important milestone\nfor carbon electronics."
    },
    {
        "anchor": "Transient response of spin Peltier effect revealed by lock-in\n  thermoreflectance measurement: Transient response of the spin Peltier effect (SPE) in a Pt/yttrium iron\ngarnet junction system has been investigated by means of a lock-in\nthermoreflectance method. We applied an alternating charge current to the Pt\nlayer to drive SPE through the spin Hall effect, and measured the AC response\nof the resultant SPE-induced temperature modulation at frequencies ranging from\n10 Hz to 1 MHz. We found that the SPE-induced temperature modulation decreases\nwith increasing the frequency when the frequency is >1 kHz. This is a\ncharacteristic feature of SPE revealed by the high frequency measurements based\non the lock-in thermoreflectance, while previous low frequency measurements\nshowed that the SPE signal is independent of the frequency. We attribute the\ndecrease of the temperature modulation to the length scale of the SPE-induced\nheat current; by comparing the experimental results with one-dimensional heat\nconduction calculations, the length scale of SPE is estimated to be 0.94\n{\\mu}m.",
        "positive": "Nonlinear optical responses of organic based indole derivative: an\n  experimental and computational study: The nonlinear optical (NLO) properties of the Indole-7-carboxyldehyde (I7C)\nhave been investigated by computational and experimental (UV-VIS, Raman) data\nanalysis. Mulliken charge analysis, molecular electrostatic potential, and\nUV-VIS absorption and vibrational Raman studies have been used to analyze the\nintra-molecular charge transfer occurrence in the probe system. Observed high\nvalue of dipole moment, linear polarizability and first order\nhyperpolarizability values suggest that the indole derivative may indeed have\npossibility to show good NLO behaviour."
    },
    {
        "anchor": "Monolayer Molybdenum Disulfide Nanoribbons with High Optical Anisotropy: Two-dimensional Molybdenum Disulfide (MoS2) has shown promising prospects for\nthe next generation electronics and optoelectronics devices. The monolayer MoS2\ncan be patterned into quasi-one-dimensional anisotropic MoS2 nanoribbons\n(MNRs), in which theoretical calculations have predicted novel properties.\nHowever, little work has been carried out in the experimental exploration of\nMNRs with a width of less than 20 nm where the geometrical confinement can lead\nto interesting phenomenon. Here, we prepared MNRs with width between 5 nm to 15\nnm by direct helium ion beam milling. High optical anisotropy of these MNRs is\nrevealed by the systematic study of optical contrast and Raman spectroscopy.\nThe Raman modes in MNRs show strong polarization dependence. Besides that the\nE' and A'1 peaks are broadened by the phonon-confinement effect, the modes\ncorresponding to singularities of vibrational density of states are activated\nby edges. The peculiar polarization behavior of Raman modes can be explained by\nthe anisotropy of light absorption in MNRs, which is evidenced by the polarized\noptical contrast. The study opens the possibility to explore\nquasione-dimensional materials with high optical anisotropy from isotropic 2D\nfamily of transition metal dichalcogenides.",
        "positive": "Spin Dynamics of a Magnetic Antivortex: We report on a study of the dynamics of a magnetic antivortex in a submicron,\nasteroid shaped, permalloy ferromagnet using micromagnetic simulations. As with\nvortex states in disk and square geometries, a gyrotropic mode was found in\nwhich a shifted antivortex core orbits about the center of the asteroid. Pulsed\nmagnetic fields were used to generate azimuthal or radial spin wave modes,\ndepending on the field orientation. The degeneracy of low frequency azimuthal\nmode frequencies is lifted by gyrotropic motion of the antivortex core, and\nrestored by inserting a hole in the center of the particle to suppress this\nmotion. We briefly compare the dynamics of the vortex state of the asteroid to\nthe antivortex. The size dependence of the antivortex modes is reported."
    },
    {
        "anchor": "Rhodium based half-Heusler alloys as possible optoelectronic and\n  thermoelectric materials: On the basis of density functional theory and semi-classical Boltzmann\ntheory, we have investigated the structural, elastic, electronic, optical and\nthermoelectric properties of 18--valence electron count rhodium based\nhalf-Heusler alloys focusing on RhTiP, RhTiAs, RhTiSb, and RhTiBi. The absence\nof imaginary frequencies in the phonon dispersion curve for these system\nverifies that they are structurally stable. RhTiP is ductile in nature, while\nothers are brittle. The alloys are found to be semiconducting with indirect\nband gaps ranging from 0.94 to 1.01 eV. Our calculations suggest these\nmaterials to have high absorption coefficient and optical conductivity in the\nultraviolet as well as visible region. While considering thermoelectricity, we\nfound that $p$--type doping is more favorable in improving the thermoelectric\nproperties. The calculated values of power factor with $p$-type doping are\ncomparable to some of the reported half-Heusler materials. The optimum figure\nof merit \\zt\\ is $\\sim1$ for RhTiBi suggesting it as a promising candidate for\nthermoelectric applications while RhTiP, RhTiAs, and RhTiSb with optimum \\zt \\\nvalues between 0.38 to 0.67 are possible candidates for use in thermoelectric\ndevices.",
        "positive": "Mechanism of Anomalous Tunneling in Condensed Bose System: We clarify the origin of anomalous tunneling [Yu. Kagan et al. Phys. Rev.\nLett. 90 (2003) 130402] i.e. the perfect transmission at low energy limit of\ntunneling of phonon excitations across the potential barrier separating two\nBose condensates. The perfect transmission is a consequence of the coincidence\nof the wave function of the excited state at low energy limit and the\nmacroscopic wave function of the condensate. We show that the perfect\ntransmission at low energy occurs even at finite temperatures within the scheme\nof Popov approximation."
    },
    {
        "anchor": "Interpretable and Explainable Machine Learning for Materials Science and\n  Chemistry: While the uptake of data-driven approaches for materials science and\nchemistry is at an exciting, early stage, to realise the true potential of\nmachine learning models for successful scientific discovery, they must have\nqualities beyond purely predictive power. The predictions and inner workings of\nmodels should provide a certain degree of explainability by human experts,\npermitting the identification of potential model issues or limitations,\nbuilding trust on model predictions and unveiling unexpected correlations that\nmay lead to scientific insights. In this work, we summarize applications of\ninterpretability and explainability techniques for materials science and\nchemistry and discuss how these techniques can improve the outcome of\nscientific studies. We discuss various challenges for interpretable machine\nlearning in materials science and, more broadly, in scientific settings. In\nparticular, we emphasize the risks of inferring causation or reaching\ngeneralization by purely interpreting machine learning models and the need of\nuncertainty estimates for model explanations. Finally, we showcase a number of\nexciting developments in other fields that could benefit interpretability in\nmaterial science and chemistry problems.",
        "positive": "Second Harmonic Generation in Chemical Vapor Deposition Synthesized CuS\n  Crystals: Copper sulfide (CuS) has garnered significant attention in various fields of\napplication due to its unique electronic, optical, and catalytic features. In\nthis study, we present the chemical vapor deposition (CVD)-based synthesis of\nultrathin CuS crystals as thin as 14 nm with lateral sizes up to 60 um. The\nstructure, morphology, and composition of the as-synthesized CuS crystals were\nthoroughly characterized. Among our results, we measured the first-order\ntemperature coefficients of Raman shifts of CuS. Moreover, we showed that CuS\ncrystals exhibited an unexpected second harmonic generation (SHG), which is\nattributed to the presence of defects in the CuS lattice. Our results suggest\nthat single crystalline CuS possesses a considerable potential for nonlinear\noptical applications in conjunction with its current applications in\nelectronics and catalysis."
    },
    {
        "anchor": "Correct Brillouin zone and electronic structure of BiPd: A promising route to the realization of Majorana fermions is in\nnon-centrosymmetric superconductors, in which spin-orbit-coupling lifts the\nspin degeneracy of both bulk and surface bands. A detailed assessment of the\nelectronic structure is critical to evaluate their suitability for this through\nestablishing the topological properties of the electronic structure. This\nrequires correct identification of the time-reversal-invariant momenta. One\nsuch material is BiPd, a recently rediscovered non-centrosymmetric\nsuperconductor which can be grown in large, high-quality single crystals and\nhas been studied by several groups using angular resolved photoemission to\nestablish its surface electronic structure. Many of the published electronic\nstructure studies on this material are based on a reciprocal unit cell which is\nnot the actual Brillouin zone of the material. We show here the consequences of\nthis for the electronic structures and show how the inferred topological nature\nof the material is affected.",
        "positive": "Topological Lifshitz Transitions and Fermi Arc Manipulation in Weyl\n  Semimetal NbAs: Surface Fermi arcs (SFAs), the unique open Fermi-surfaces (FSs) discovered\nrecently in topological Weyl semimetals (TWSs), are unlike closed FSs in\nconventional materials and can give rise to many exotic phenomena, such as\nanomalous SFA-mediated quantum oscillations, chiral magnetic effects,\nthree-dimensional quantum Hall effect, non-local voltage generation and\nanomalous electromagnetic wave transmission. Here, by using in-situ surface\ndecoration, we demonstrate successful manipulation of the shape, size and even\nthe connections of SFAs in a model TWS, NbAs, and observe their evolution that\nleads to an unusual topological Lifshitz transition not caused by the change of\nthe carrier concentration. The phase transition teleports the SFAs between\ndifferent parts of the surface Brillouin zone. Despite the dramatic surface\nevolution, the existence of SFAs is robust and each SFA remains tied to a pair\nof Weyl points of opposite chirality, as dictated by the bulk topology."
    },
    {
        "anchor": "Thermal Visualization of Buried Interfaces by Transient and Steady-State\n  Responses of Time-Domain Thermoreflectance: Thermal resistances from interfaces impede heat dissipation in\nmicro/nanoscale electronics, especially for high-power electronics. Despite the\ngrowing importance of understanding interfacial thermal transport, advanced\nthermal characterization techniques which can visualize thermal conductance\nacross buried interfaces, especially for nonmetal-nonmetal interfaces, are\nstill under development. This work reports a dual-modulation-frequency TDTR\nmapping technique to visualize the thermal conduction across buried\nsemiconductor interfaces for beta-Ga2O3-SiC samples. Both the beta-Ga2O3\nthermal conductivity and the buried beta-Ga2O3-SiC thermal boundary conductance\n(TBC) are visualized for an area of 200 um x 200 um. Areas with low TBC values\n( smaller than 20 MW/m2-K) are successfully identified on the TBC map, which\ncorrespond to weakly bonded interfaces caused by high-temperature annealing.\nThe steady-state temperature rise (detector voltage), usually ignored in TDTR\nmeasurements, is found to be able to probe TBC variations of the buried\ninterfaces without the limit of thermal penetration depth. This technique can\nbe applied to detect defects/voids in deeply buried heterogeneous interfaces\nnon-destructively, and also opens a door for the visualization of thermal\nconductance in nanoscale nonhomogeneous structures.",
        "positive": "Correct form of the electron wavefunction in periodic solids: The Bloch wavefunction leads either to mathematically impossible consequences\nor suggests that the ground state energy is a function of size and shape when\nthe geometry of large crystals is considered in detail. It is incompatible with\nthe assumption underlying the Born-von Karman periodic boundary condition. The\nsource of the difficulty is the incorrect dependence of the Bloch wavefunction\non the wavenumber index k. The mathematically impossible consequences can be\novercome if the periodic part of the electron wavefunction is represented as\nun(r), which is dependent only on the band index, n, and is independent of the\nwavenumber index k. This correct form of the wavefunction is consistent with\nthe Bloch theorem and with all other properties of Bloch wavefunctions. The\ncorrect form is also consistent with the Born-von Karman periodic boundary\ncondition. The correct form of the electronic wavefunction in a periodic solid\nhas profound consequences. It simplifies the calculation of electronic\nstructure as only one wavefunction per band, un(r), needs to be evaluated. It\nbrings about a conceptual unification between the band picture favored by\nphysicists and the bond picture favored by chemists. The correct form of the\nelectron wavefunction will simplify the understanding of many phenomena\ninvolving valence electrons."
    },
    {
        "anchor": "Acoustic surface plasmons in the noble metals Cu, Ag, and Au: We have performed self-consistent calculations of the dynamical response of\nthe (111) surface of the noble metals Cu, Ag, and Au. Our results indicate that\nthe partially occupied surface-state band in these materials yields the\nexistence of acoustic surface plasmons with linear dispersion at small wave\nvectors. Here we demonstrate that the sound velocity of these low-energy\ncollective excitations, which had already been predicted to exist in the case\nof Be(0001), is dictated not only by the Fermi velocity of the two-dimensional\nsurface-state band but also by the nature of the decay and penetration of the\nsurface-state orbitals into the solid. Our linewidth calculations indicate that\nacoustic surface plasmons should be well defined in the energy range from zero\nto $\\sim 400$ meV.",
        "positive": "Enhancing Chemical Stability and Photovoltaic Properties of Highly\n  Efficient Nonfullerene Acceptors by Chalcogen Substitution: Insights from\n  Quantum Chemical Calculations: The chemical stability of nonfullerene acceptor (NFA) is the Achilles' heel\nof the research on state-of-the-art organic solar cells (OSC). The fragility of\nthe NFA is essentially due to the weak bond that links the central donor core\nof the molecules with their acceptor moieties at the edges. Here we proposed\nthe replacement of thiophene at the outer-core position of traditional NFAs for\ntellurophene, a hitherto unexplored modification. Since tellurium is a\ndistinctive element among chalcogens, the basic features of Te compounds cannot\nbe deduced straightforwardly from the properties of their lighter analogues, S\nand Se. The modeled Te-based NFAs presented interesting features like stronger\nintra- and intermolecular interactions induced by a distinctive secondary bond\neffect between the end acceptor moiety and the outer chalcogen atom. This\ndesign strategy resulted in stiffer molecules with red-shifted absorption\nspectra and less susceptible to degradation verified through stress tests and\nvibrational spectra analysis. Besides that, a weakened exciton binding energy\nhas been found, opening the possibility of blends with a lower driving force.\nOur results shed light on several aspects of selenation and telluration of\ntraditional NFAs, providing valuable insights into the possible consequences\nfor OSCs applications."
    },
    {
        "anchor": "Direct evidence for ferromagnetic spin polarization in gold\n  nanoparticles: We report the first direct observation of ferromagnetic spin polarization of\nAu nanoparticles with a mean diameter of 1.9 nm using X-ray magnetic circular\ndichroism (XMCD). Owing to the element selectivity of XMCD, only the gold\nmagnetization is explored. Magnetization of gold atoms estimated by XMCD shows\na good agreement with the results obtained by conventional magnetometry. This\nresult is evidence of intrinsic spin polarization in nano-sized gold.",
        "positive": "Two-phonon scattering in non-polar semiconductors: a first-principles\n  study of warm electron transport in Si: The ab-initio theory of charge transport in semiconductors typically employs\nthe lowest-order perturbation theory in which electrons interact with one\nphonon (1ph). This theory is accepted to be adequate to explain the low-field\nmobility of non-polar semiconductors but has not been tested extensively beyond\nthe low-field regime. Here, we report first-principles calculations of the\nelectric field-dependence of the electron mobility of Si as described by the\nwarm electron coefficient, $\\beta$. Although the 1ph theory overestimates the\nlow-field mobility by only around 20%, it overestimates $\\beta$ by over a\nfactor of two over a range of temperatures and crystallographic axes. We show\nthat the discrepancy in $\\beta$ is reconciled by inclusion of on-shell iterated\n2-phonon (2ph) scattering processes, indicating that scattering from\nhigher-order electron-phonon interactions is non-negligible even in non-polar\nsemiconductors. Further, a ~20% underestimate of the low-field mobility with\n2ph scattering suggests that non-trivial cancellations may occur in the\nperturbative expansion of the electron-phonon interaction."
    },
    {
        "anchor": "Retrieval of depth profile of nano scale thin films by one directional\n  polarization analysis in neutron specular reflectometry: Recently it has been shown that the modules and phase of complex reflection\ncoefficient can be determined by using a magnetic substrate and polarized\nneutrons. Several other methods have also been worked out based on measurement\nof polarizations of reflected neutrons from magnetic reference layers and\nmagnetic substrate. However, due to the fact that available reflectometers are\nlimited in the choice of polarization of reflected beam in the same direction\nas the polarization of the incident beam, neither of the methods which are\nbased on polarization analysis, has been proven to be experimentally practical.\nIn this paper, we have proposed a new method for determining the phase of\nreflection coefficient which is based on two measurements of polarization which\ncorrespond to two magnetic fields with the same magnitudes and different\norientations. The polarization analysis is performed in the same direction as\nthe polarization of the incident beam and is well suited for available\nreflectometers. The problems envisaged in implementation of the method are also\ndiscussed.",
        "positive": "Field emission mechanisms of graphitic nanostructures: Field emission (FE) and the electronic-states origin of graphitic\nnanostructures were investigated by first-principles calculations based on\ntime-dependent density-functional theory. We find that the FE current from\ngraphitic ribbons changes remarkably depending on the hydrogen termination and\nthe direction of the applied electric field. Also, the FE current from graphene\nsheets shows a dramatic increase around vacancy defects. We verified, through\nthe analysis of local electronic structures and energy distributions of emitted\nelectrons, that the dangling-bond (or $\\sigma$) character is responsible for\nthese results and governs the nature of the FE of graphitic nanostructures."
    },
    {
        "anchor": "Temperature-independent ferromagnetic resonance shift in Bi-doped YIG\n  garnets through magnetic anisotropy tuning: Thin garnet films are becoming central for magnon-spintronics and\nspin-orbitronics devices as they show versatile magnetic properties together\nwith low magnetic losses. These fields would benefit from materials in which\nheat does not affect the magnetization dynamics, an effect known as the\nnon-linear thermal frequency shift. In this study, low damping Bi substituted\nIron garnet (Bi:YIG) ultra-thin films have been grown using Pulsed Laser\nDeposition. Through a fine tuning of the growth parameters, the precise control\nof the perpendicular magnetic anisotropy allows to achieve a full compensation\nof the dipolar magnetic anisotropy. Strikingly, once the growth conditions are\noptimized, varying the growth temperature from 405 {\\deg}C to 475 {\\deg}C as\nthe only tuning parameter induces the easy-axis to go from out-of-plane to\nin-plane. For films that are close to the dipolar compensation, Ferromagnetic\nResonance measurements yield an effective magnetization $\\mu _{0}M_{eff} (T)$\nthat has almost no temperature dependence over a large temperature range (260 K\nto 400 K) resulting in an anisotropy temperature exponent of 2. These findings\nput Bi:YIG system among the very few materials in which the temperature\ndependence of the magnetic anisotropy varies at the same rate than the\nsaturation magnetization. This interesting behavior is ascribed\nphenomenologically to the sizable orbital moment of $Bi^{3+}$.",
        "positive": "Decay of Metastable Nonequilibrium Phases, Enhanced Reaction Rate, and\n  Dynamic Phase Transition in a Model of CO Oxidation with CO Desorption: We present a computational study of the dynamic behavior of a\nZiff-Gulari-Barshad model of CO oxidation with CO desorption on a catalytic\nsurface. Our results provide further evidence that below a critical desorption\nrate the model exhibits a non-equilibrium, first-order phase transition between\nlow and high CO coverage phases. Our kinetic Monte Carlo simulations indicate\nthat the transition process between these phases follows a decay mechanism very\nsimilar to the one described by the classic Kolmogorov-Johnson-Mehl-Avrami\ntheory of phase transformation by nucleation and growth. We measure the\nlifetimes of the metastable phases on each side of the transition line and find\nthat they are strongly dependent on the direction of the transformation, i.e.,\nfrom low to high coverage or vice versa. Inspired by this asymmetry, we\nintroduce a square-wave periodic external forcing, whose two parameters can be\ntuned to enhance the catalytic activity. At CO desorption rates below the\ncritical value, we find that this far-from-equilibrium system undergoes a\ndynamic phase transition between a CO_2 productive phase and a nonproductive\none. In the space of the parameters of the periodic external forcing, this\nnonequilibrium phase transition defines a line of critical points. The maximum\nenhancement rate for the CO_2 production rate occurs near this critical line."
    },
    {
        "anchor": "O2 Adsorption on Defective Penta-Graphene Lattices: Penta-Graphene (PG) was theoretically proposed as a new carbon allotrope with\na 2D structure. PG has revealed interesting gas sensing properties. Here, the\nstructural and electronic properties of defective PG lattices interacting with\nan oxygen molecule were theoretically studied by employing density functional\ntheory calculations. Results show that PG lattices with a sp3-like single-atom\nvacancy presented higher adsorption energy than the sp2-like one. Remarkably,\nPG lattices with a sp3-like defect presented a clear degree of selectivity for\nthe molecule orientation by changing their bandgap configurations. Importantly,\nthe adsorption energies were obtained using the improved Lennard-Jones (ILJ)\npotential.",
        "positive": "Kolmogorov-Crespi Potential For Multilayer Transition Metal\n  Dichalcogenides: Capturing Structural Transformations In Moir\u00e9\n  Superlattices: We develop parameters for the interlayer Kolmogorov-Crespi (KC) potential to\nstudy structural features of four transition metal dichalcogenides (TMDs):\nMoS$_2$, WS$_2$, MoSe$_2$ and WSe$_2$. We also propose a mixing rule to extend\nthe parameters to their heterostructures. Moir\\'e superlattices of twisted\nbilayer TMDs have been recently shown to host shear solitons, topological point\ndefects and ultraflatbands close to the valence band edge. Performing\nstructural relaxations at the DFT level is a major bottleneck in the study of\nthese systems. We show that the parametrized KC potential can be used to obtain\natomic relaxations in good agreement with DFT relaxations. Furthermore, the\nmoir\\'e superlattices relaxed using DFT and the proposed forcefield yield very\nsimilar electronic band structures."
    },
    {
        "anchor": "Multiplet Effects in the Electronic Correlation of One-Dimensional\n  Magnetic Transition-Metal Oxides on Metals: We use the constrained random phase approximation (cRPA) method to calculate\nthe Hubbard $U$ parameter in four one-dimensional magnetic transition metal\natom oxides of composition XO$_2$ (X = Mn, Fe, Co, Ni) on Ir(100). In addition\nto the expected screening of the oxide, i.e., a significant reduction of the\n$U$ value by the presence of the metal substrate, we find a strong dependence\non the electronic configuration (multiplet) of the X($d$) orbital. Each\nparticular electronic configuration attained by atom X is dictated by the O\nligands, as well as by the charge transfer and hybridization with the Ir(100)\nsubstrate. We find that MnO$_2$ and NiO$_2$ chains exhibit two different\nscreening regimes, while the case of CoO$_2$ is somewhere in between. The\nelectronic structure of the MnO$_2$ chain remains almost unchanged upon\nadsorption. Therefore, in this regime, the additional screening is\npredominantly generated by the electrons of the neighboring metal surface\natoms. The screening strength for NiO$_2$/Ir(100) is found to depend on the\nNi($d$) configuration in the adsorbed state. The case of FeO$_2$ shows an\nexceptional behavior, as it is the only insulating system in the absence of\nmetallic substrate and, thus, it has the largest $U$ value. However, this value\nis significantly reduced by the two mentioned screening effects after\nadsorption.",
        "positive": "Influence of Atomic Roughness at The Uncompensated Fe/CoO (111)\n  Interface on Exchange Bias Effect: The effect of interface roughness of ferromagnetic and antiferromagnetic\nlayers on exchange bias is still not well understood. In this report we have\ninvestigated the effect of surface roughness in (111)-oriented\nantiferromagnetic CoO films on exchange bias with ferromagnetic Fe grown on\ntop. The surface roughness is controlled at the atomic scale, over a range\nbelow ~ 0.35 nm, by varying layer thickness of the CoO films. It is observed\nthat both exchange bias field ($H_{E}$) and coercivity ($H_{C}$) extensively\ndepend on the atomic scale roughness of the CoO (111) at the interface with Fe\nfilm. An opposite dependence of $H_{E}$ and $H_{C}$ on interface roughness was\nfound, which was ascribed to partially compensated spin states induced by the\natomic roughness at the fully uncompensated CoO (111) surfaces and was\ncorroborated using the Monte Carlo simulations. Moreover, the onset temperature\nfor $H_{C}$ is found to be up to ~ 80 K below the blocking temperature\n($T_{B}$) and the temperature dependence of $H_{C}$ follows the power law with\na critical exponent equal to one, which indicates that, in this system, $H_{C}$\nis more of an interface-related property than $H_{E}$."
    },
    {
        "anchor": "Peridynamic micromechanics of composites: a review: We consider a static peridynamic (proposed by Silling, see J. Mech. Phys.\nSolids 2000; 48:175--209) composite materials (CMs) of both the random and\nperiodic structures. In the framework of the second background of\nmicromechanics (also called computational analytical micromechanics, CAM), one\nproved that local micromechanics (LM) and peridynamic micromechanics (PM) are\nformally similar to each other for CM of both random and periodic structures.\nIt allows straightforward generalization of LM methods to their PM\ncounterparts. It turns out that a plurality of micromechanics phenomena [e.g.\nstatistically homogeneous and inhomogeneous media, inhomogeneous loading\n(inhomogeneous body force is included), nonlinear and nonlocal constitutive\nlaws of phases, and coupled physical phenomena] can be analyzed by one\nuniversal tool (called CAM), which is sufficiently flexible and based on\nphysically clear hypotheses that can be modified and improved if necessary (up\nto abandonment of these hypotheses) in the framework of a unique scheme for\nanalyses of a wide class of mentioned problems. The schemes of these approaches\nare considered in the current paper.",
        "positive": "Search for incoherent tunnel fluctuations of the magnetisation in\n  nanoparticles of artificial ferritin: The magnetic behaviour of nanoparticles of antiferromagnetic ferritin, with a\nmean Fe loading of 410 atoms per core, has been investigated by 57Fe Mossbauer\nabsorption spectroscopy down to very low temperature (34mK). In previous\nexperi- ments of frequency dependent magnetic susceptibility and magnetic noise\nperformed at 25mK in similar samples, it was claimed that a resonance at a\nfrequency of about 10**8 Hz, due to a macroscopic coherent state, had been\nobserved. However, our search of incoherent tunnel fluctuations around 10**8 Hz\nusing 57Fe Mossbauer spectroscopy, whose \"window\" of measurement of fluctuation\nfrequencies lies in this frequency range, was unsuccessful. This casts a doubt\nabout the previous observa- tion of macroscopic quantum coherence in ferritin."
    },
    {
        "anchor": "Engineering Polarization Rotation in Ferroelectric Bismuth Titanate: Here, we report a combined experimental-theoretical study showing that\ncollective application of rare earth doping on A-site and epitaxial strain to\nferroelectric bismuth titanate does not lead to a very large c-axis\npolarization as reported previously. Further first principles calculations\nbased on the examination of polarization tensor suggest that simultaneous Bi\nand Ti site doping could result in moderate polarization along c-axis of\nbismuth titanate which is typically a preferential axis of film growth and thus\nenabling c axis oriented films to have appreciable polarization. This approach\ncould also be applicable to other ferroic oxides where one can correlate the\ndoping, epitaxial strain, and polarization to design materials compositions\nresulting in epitaxial films grown along desired directions yielding\nsubstantial polarization.",
        "positive": "Island nucleation in the presence of step edge barriers: Theory and\n  applications: We develop a theory of nucleation on top of two-dimensional islands bordered\nby steps with an additional energy barrier $\\Delta E_S$ for descending atoms.\nThe theory is based on the concept of the residence time of an adatom on the\nisland,and yields an expression for the nucleation rate which becomes exact in\nthe limit of strong step edge barriers. This expression differs qualitatively\nand quantitatively from that obtained using the conventional rate equation\napproach to nucleation [J. Tersoff et al., Phys. Rev. Lett.72, 266 (1994)]. We\nargue that rate equation theory fails because nucleation is dominated by the\nrare instances when two atoms are present on the island simultaneously. The\ntheory is applied to two distinct problems: The onset of second layer\nnucleation in submonolayer growth, and the distribution of the sizes of top\nterraces of multilayer mounds under conditions of strong step edge barriers.\nApplication to homoepitaxial growth on Pt(111) yields the estimate $\\Delta E_S\n\\geq 0.33$ eV for the additional energy barrier at CO-decorated steps."
    },
    {
        "anchor": "Lattice dynamics of quasi-2D perovskites from first-principles: We present the vibrational properties and phonon dispersion for quasi-2D\nhybrid organic-inorganic perovskites (BA)$_2$CsPb$_2$I$_7$,\n(HA)$_2$CsPb$_2$I$_7$, (BA)$_2$(MA)Pb$_2$I$_7$, and (HA)$_2$(MA)Pb$_2$I$_7$\ncalculated from first principles. Given the highly complex nature of these\ncompounds, we first perform careful benchmarking and convergence testing to\nidentify suitable parameters to describe their structural features and\nvibrational properties. We find that the inclusion of van der Waals corrections\non top of generalized gradient approximation (GGA) exchange-correlation\nfunctionals provides the best agreement for the equilibrium structure relative\nto experimental data. We then compute vibrational properties under the harmonic\napproximation. We find that stringent energy cut-offs are required to obtain\nwell-converged phonon properties, and once converged, the harmonic\napproximation can capture key physics for such a large, hybrid\ninorganic-organic system with vastly different atom types, masses, and\ninteratomic interactions. We discuss the obtained phonon modes and dispersion\nbehavior in the context of known properties for bulk 3D perovskites and ligand\nmolecular crystals. While many vibrational properties are inherited from the\nparent systems, we also observe unique coupled vibrations that cannot be\nassociated with vibrations of the pure constituent perovskite and ligand\nsubphases. Dispersive low energy phonon branches primarily occur in the\nin-plane direction and within the perovskite subphase, and arise from bending\nand breathing modes of the equatorial Pb-I network within the perovskite\noctahedral plane.",
        "positive": "Diffuse scattering in ice Ih: Single crystals of ice Ih, extracted from the subglacial Lake Vostok\naccretion ice layer (3621 m depth) were investigated by means of diffuse x-ray\nscattering and inelastic x-ray scattering. The diffuse scattering was\nidentified as mainly inelastic and rationalized in the frame of ab initio\ncalculations for the ordered ice XI approximant. Together with Monte-Carlo\nmodelling our data allowed reconsidering previously available neutron diffuse\nscattering data of heavy ice as the sum of thermal diffuse scattering and\nstatic disorder contribution."
    },
    {
        "anchor": "Two-dimensional transition metal chalcogenides with hexagonal and\n  orthorhombic structures: candidates for auxetics and photocatalysts: In this paper, we perform theoretical study on the physical properties of\ntwo-dimensional transition metal chalcogenides MX$_{2}$ and M$_{2}$X$_{3}$ (M=\nNi, Pd; X= S, Se, Te). These studied materials are classified in three stable\nphases according to their lattice structures: hexagonal MX$_{2}$, orthorhombic\nMX$_{2}$ and orthorhombic M$_{2}$X$_{3}$. They have either isotropic or\nanisotropic in-plane properties depending on their symmetries. In particular,\nthe orthorhombic MX$_{2}$ and M$_{2}$X$_{3}$ have low lattice symmetry and\npresent highly anisotropic properties. The orthorhombic MX$_{2}$ possess giant\nnegative in-plane Poisson's ratios, different from the other two phases.\nMoreover, by joint analysis of band gap, band edge and optical absorption, the\northorhombic MX$_{2}$ and M$_{2}$X$_{3}$ are found to be highly efficient as\nwater splitting photocatalysts within the visible and ultraviolet sunlight\nregions.",
        "positive": "Signature of topological non-trivial band structure in\n  Ta$_{3}$SiTe$_{6}$: The study of topology protected electronic properties is a fascinating topic\nin present day condensed matter physics research. New topological materials are\nfrequently being proposed and explored through various experimental techniques.\nTa$_{3}$SiTe$_{6}$ is a newly predicted topological semimetal with fourfold\ndegenerate nodal-line crossing in absence of spin-orbit coupling (SOC) and an\nhourglass Dirac loop, when SOC is included. Recent angle-resolved photoemission\nspectroscopy study in this material, has also confirmed Dirac like dispersions\nand two nodal-lines near the Fermi energy, protected by nonsymmorphic glide\nmirror symmetry. In this work, we present the detailed magnetotransport\nproperties of single crystalline Ta$_{3}$SiTe$_{6}$. A nonsaturating\nmagnetoresistance has been observed. Hall measurements reveal hole type charge\ncarriers with high carrier density and a moderate value of carrier mobility.\nFurthermore, we report a robust planar Hall effect, which persists up to high\ntemperatures. These results validate the nontrivial nature of the electronic\nband structure."
    },
    {
        "anchor": "High Pressure Phase Diagram of Beryllium from \\emph{Ab Initio} Free\n  Energy Calculations: We use first principles molecular dynamics simulations coupled to the\nthermodynamic integration method to study the hcp-bcc transition and melting of\nberyllium up to a pressure of 1600~GPa. We derive the melting line by equating\nsolid and liquid Gibbs free energies, and represent it by a Simon Glatzel fit\n$T_m= 1564~\\text{K} (1 + P/(15.6032 ~\\text{GPa}))^{0.383}$, which is in good\nagreement with previous two-phase simulations below 6000~K. We also derive the\nhcp-bcc solid-solid phase boundary and show the quasiharmonic approximation\nunderestimates the stability of the hcp structure, predicting lower transition\npressures between hcp and bcc phases. However, our results are consistent with\nthe stability regime predicted by the phonon quasiparticle method. We also\npredict that hcp-bcc-liquid triple point is located at 164.7~GPa and 4314~K. In\naddition, we compute the shock Hugoniot curve, and show that it is in good\nagreement with experiments, intersecting our derived melting curve at\n$\\sim$235~GPa at 4900~K. Finally, we show that an isentropic compression path\nthat intersects the melting curve at both low and high temperature in the\nliquid regime, can reappear in the solid after a gap as large as 7000~K.\nTherefore, we predict that a large section of the melting curve could be\nsampled, in principle, by a ramp compression experiment, where solid and liquid\nBe would coexist as the sample is compressed.",
        "positive": "Enhancement of spin Hall magnetoresistance effect in CoFe2O4/Pt/CoFe2O4\n  trilayers: The spin Hall magnetoresistance (SMR) phenomenon includes the fundamental\nphysics of spin current, and originates from spin accumulation at an interface\nowing to the spin Hall effect. Although bilayers are the simplest structure\nexhibiting SMR, these exploit spin accumulation at only one side of a layer.\nHerein, trilayers of CoFe2O4/Pt/CoFe2O4 were fabricated and their spin Hall\nmagnetoresistance was investigated. The trilayer structure featuring a thin Pt\nlayer exhibited an SMR ratio four times that of a CoFe2O4/Pt bilayer. Further,\nthe SMR ratio exhibited a dependence on Pt layer thickness that can be\nattributed to interference of the spin accumulations at both sides. Herein,\nseveral parameters such as spin diffusion length and mixing conductance were\nderived using the theory of Chen et al."
    },
    {
        "anchor": "Structure of a Zn monolayer on Ag(111) and Ag(110) substrates: an AES,\n  LEED and STM study: Auger Electron Spectroscopy, Low Energy Electron Diffraction and Scanning\nTunneling Microscopy have been used to study the atomic structure of a Zn\nmonolayer deposited on Ag(111) and Ag(110) substrates at room temperature. On\nboth faces, there is formation of a close packed monolayer of Zn covering the\nentire substrate surface and giving rise to specific Moir{\\'e} patterns. From a\ncomprehensive LEED and STM data analysis, we deduce that the Zn monolayer\nadopts a (111) structure equivalent to a pure Zn layer rotated with respect to\nthe silver substrate, of about $1.5^\\circ$ on the Ag(111) face and of about\n$4.5^\\circ$ on the Ag(110) face giving rise respectively to\n($\\sqrt{156}\\times\\sqrt{156})R18^\\circ$ and c(12x6) superstructures.",
        "positive": "Nanoacoustic Defect Manipulation in Solids: Within a nanoscale volume, an acoustic wave interacts with radiation defects\nin ionic solids. The radiation-induced optical absorption in ionic crystals is\nremarkably removed by a room-temperature ultrasonic treatment of the crystals.\nIt is shown that the effect can be explained by defect migration processes\noccurring in ultrasonic fields. The inter-ion charge exchange, termed as\nacoustically-stimulated chemical reaction, is furthermore suggested to occur\naffecting the defect migration. This new method of a cold annealing of\nradiation defects in solids can be regarded as nanoacoustic defect\nmanipulation."
    },
    {
        "anchor": "Spin relaxation in (110) and (001) InAs/GaSb superlattices: We report an enhancement of the electron spin relaxation time (T1) in a (110)\nInAs/GaSb superlattice by more than an order of magnitude (25 times) relative\nto the corresponding (001) structure. The spin dynamics were measured using\npolarization sensitive pump probe techniques and a mid-infrared, subpicosecond\nPPLN OPO. Longer T1 times in (110) superlattices are attributed to the\nsuppression of the native interface asymmetry and bulk inversion asymmetry\ncontributions to the precessional D'yakonov Perel spin relaxation process.\nCalculations using a nonperturbative 14-band nanostructure model give good\nagreement with experiment and indicate that possible structural inversion\nasymmetry contributions to T1 associated with compositional mixing at the\nsuperlattice interfaces may limit the observed spin lifetime in (110)\nsuperlattices. Our findings have implications for potential spintronics\napplications using InAs/GaSb heterostructures.",
        "positive": "Heat assisted magnetic recording of bit patterned media beyond 10\n  Tb/in$^2$: The limits of the areal storage density as can be achieved with heat assisted\nmagnetic recording (HAMR) are still an open issue. We want to address this\ncentral question and present the design of a possible bit patterned medium with\nan areal storage density above 10 Tb/in$^2$. The model uses hard magnetic\nrecording grains with 5 nm diameter and 10 nm height. It assumes a realistic\ndistribution of the Curie temperature of the underlying material as well as a\nrealistic distribution of the grain size and the grain position. In order to\ncompute the areal density we analyze the detailed switching behavior of a\nrecording bit under different external conditions, which allows to compute the\nbit error rate of a recording process (shingled and conventional) for different\ngrain spacings and write head positions. Hence, we are able to optimize the\nareal density of the presented medium."
    },
    {
        "anchor": "Structural sensitivity of the spin Hall magnetoresistance in\n  antiferromagnetic thin films: Reading the magnetic state of antiferromagnetic (AFM) thin films is key for\nAFM spintronic devices. We investigate the underlying physics behind the spin\nHall magnetoresistance (SMR) of bilayers of platinum and insulating AFM\nhematite ({\\alpha}-Fe2O3) and find an SMR efficiency of up to 0.1%, comparable\nto ferromagnetic based structures. To understand the observed complex SMR field\ndependence, we analyse the effect of misalignments of the magnetic axis that\narise during growth of thin films, by electrical measurements and direct\nmagnetic imaging, and find that a small deviation can result in significant\nsignatures in the SMR response. This highlights the care that must be taken\nwhen interpreting SMR measurements on AFM spin textures.",
        "positive": "Atomic cluster expansion for Pt-Rh catalysts: From ab initio to the\n  simulation of nanoclusters in few steps: Insight into structural and thermodynamic properties of nanoparticles is\ncrucial for designing optimal catalysts with enhanced activity and stability.\nWe present a semi-automated workflow for parameterizing the atomic cluster\nexpansion (ACE) from ab initio data. The main steps of the workflow are the\ngeneration of training data from accurate electronic structure calculations, an\nefficient fitting procedure supported by active learning and uncertainty\nindication, and a thorough validation. We apply the workflow to the simulation\nof binary Pt-Rh nanoparticles that are important for catalytic applications. We\ndemonstrate that the Pt-Rh ACE is able to reproduce accurately a broad range of\nfundamental properties of the elemental metals as well as their compounds while\nretaining an outstanding computational efficiency. This enables a direct\ncomparison of simulations to high resolution experiments."
    },
    {
        "anchor": "Magnonic spin-wave modes in CoFeB antidot lattices: In this manuscript time-resolved magneto-optical Kerr effect experiments on\nstructured CoFeB films are presented. The geometries considered are two\ndimensional square lattices of micrometer-sized antidots, fabricated by a\nfocused ion beam. The spin-wave spectra of these magnonic crystals show a novel\nprecessional mode, which can be related to a Bloch state at the zone boundary.\nAdditionally, another magnetic mode of different nature appears, whose\nfrequency displays no dependence on the externally applied magnetic field.\nThese findings are interpreted as delocalized and localized modes,\nrespectively.",
        "positive": "Octagraphene as a Versatile Carbon Atomic Sheet for Novel Nanotubes,\n  Unconventional Fullerenes and Hydrogen Storage: We study a versatile structurally favorable periodic $sp^2$-bonded carbon\natomic planar sheet with $C_{4v}$ symmetry by means of the first-principles\ncalculations. This carbon allotrope is composed of carbon octagons and squares\nwith two bond lengths and is thus dubbed as octagraphene. It is a semimetal\nwith the Fermi surface consisting of one hole and one electron pocket, whose\nlow-energy physics can be well described by a tight-binding model of\n$\\pi$-electrons. Its Young's modulus, breaking strength and Poisson's ratio are\nobtained to be 306 $N/m$, 34.4 $N/m$ and 0.13, respectively, which are close to\nthose of graphene. The novel sawtooth and armchair carbon nanotubes as well as\nunconventional fullerenes can also be constructed from octagraphene. It is\nfound that the Ti-absorbed octagraphene can be allowed for hydrogen storage\nwith capacity around 7.76 wt%."
    },
    {
        "anchor": "Magnetically-dressed CrSBr exciton-polaritons in ultrastrong coupling\n  regime: The strong coupling between photons and matter excitations such as excitons,\nphonons, and magnons is of central importance in the study of light-matter\ninteractions. Bridging the flying and stationary quantum states, the strong\nlight-matter coupling enables the coherent transmission, storage, and\nprocessing of quantum information, which is essential for building photonic\nquantum networks. Over the past few decades, exciton-polaritons have attracted\nsubstantial research interest due to their half-light-half-matter bosonic\nnature. Coupling exciton-polaritons with magnetic orders grants access to rich\nmany-body phenomena, but has been limited by the availability of material\nsystems that exhibit simultaneous exciton resonances and magnetic ordering.\nHere we report magnetically-dressed microcavity exciton-polaritons in the van\nder Waals antiferromagnetic (AFM) semiconductor CrSBr coupled to a Tamm plasmon\nmicrocavity. Angle-resolved spectroscopy reveals an exceptionally high\nexciton-polariton coupling strength attaining 169 meV, demonstrating\nultrastrong coupling that persists up to room temperature.\nTemperature-dependent exciton-polariton spectroscopy senses the magnetic order\nchange from AFM to paramagnetism in CrSBr, confirming its magnetic nature. By\napplying an out-of-plane magnetic field, an effective tuning of the polariton\nenergy is further achieved while maintaining the ultrastrong exciton-photon\ncoupling strength, which is attributed to the spin canting process that\nmodulates the interlayer exciton interaction. Our work proposes a hybrid\nquantum platform enabled by robust opto-electronic-magnetic coupling, promising\nfor quantum interconnects and transducers.",
        "positive": "Switching on surface conduction in a topological insulator: The protected surface conduction of topological insulators is in high demand\nfor the next generation of electronic devices. What is needed to move forward\nare robust settings where topological surface currents can be controlled by\nsimple means, ideally by the application of external stimuli. Surprisingly,\nthis direction is only little explored. In this work we demonstrate that we can\nboost the surface conduction of a topological insulator by both light and\nelectric field. This happens in a fully controlled way, and the additional\nDirac carriers exhibit ultra-long lifetimes. We provide a comprehensive\nunderstanding, namely that carriers are injected from the bulk to the surface\nstates across an intrinsic Schottky barrier. We expect this mechanism to be at\nplay in a broad range of materials and experimental settings."
    },
    {
        "anchor": "Bulk band inversion and surface Dirac cones in LaSb and LaBi :\n  Prediction of a new topological heterostructure: We perform \\textit{ab initio} investigations of the bulk and surface band\nstructures of LaSb and LaBi and resolve the existing disagreements about the\ntopological property of LaSb, considering LaBi as a reference. We examine the\nbulk band structure for band inversion, along with the stability of surface\nDirac cones (if any) to time-reversal-preserving perturbations, as a strong\ndiagnostic test for determining the topological character of LaSb, LaBi and\nLaSb-LaBi multilayer. A detailed \\textit{ab initio} investigation of a\nmultilayer consisting of alternating unit cells of LaSb and LaBi shows the\npresence of band inversion in the bulk and a massless Dirac cone on the (001)\nsurface, which remains stable under the influence of time-reversal-preserving\nperturbations, thus confirming the topologically non-trivial nature of the\nmultilayer in which the electronic properties can be tailored as per\nrequirement. A detailed $\\mathbb{Z}_2$ invariant calculation is performed to\narrive at a holistic conclusion.",
        "positive": "Low Thermal Conductivity Phase Change Memory Superlattices: Phase change memory devices are typically reset by melt-quenching a material\nto radically lower its electrical conductance. The high power and concomitantly\nhigh current density required to reset phase change materials is the major\nissue that limits the access times of 3D phase change memory architectures.\nPhase change superlattices were developed to lower the reset energy by\nconfining the phase transition to the interface between two different phase\nchange materials. However, the high thermal conductivity of the superlattices\nmeans that heat is poorly confined within the phase change material, and most\nof the thermal energy is wasted to the surrounding materials. Here, we\nidentified Ti as a useful dopant for substantially lowering the thermal\nconductivity of Sb2Te3-GeTe superlattices whilst also stabilising the layered\nstructure from unwanted disordering. We demonstrate via laser heating that\nlowering the thermal conductivity by doping the Sb2Te3 layers with Ti halves\nthe switching energy compared to superlattices that only use interfacial phase\nchange transitions and strain engineering. The thermally optimized superlattice\nhas (0 0 l) crystallographic orientation yet a thermal conductivity of just\n0.25 W/m.K in the \"on\" (set) state. Prototype phase change memory devices that\nincorporate this Ti-doped superlattice switch faster and and at a substantially\nlower voltage than the undoped superlattice. During switching the Ti-doped\nSb2Te3 layers remain stable within the superlattice and only the Ge atoms are\nactive and undergo interfacial phase transitions. In conclusion, we show the\npotential of thermally optimised Sb2Te3-GeTe superlattices for a new generation\nof energy-efficient electrical and optical phase change memory."
    },
    {
        "anchor": "Two-Stage Proximity-Induced Gap-Opening in Topological Insulator -\n  Insulating Ferromagnet (Bi$_x$Sb$_{1-x}$)$_2$Te$_3$ - EuS Bilayers: To further investigate the interplay between ferromagnetism and topological\ninsulators, thin films of the low-carrier topological insulator\n(Bi$_x$Sb$_{1-x}$)$_2$Te$_3$ were deposited on the insulating ferromagnet EuS\n(100) in situ. AC susceptibility indicates magnetic anomalies between\n$T\\approx30~\\mathrm{K}$ and $T\\approx60~\\mathrm{K}$, well above the Curie\ntemperature $T_C \\approx 15~\\mathrm{K}$ of EuS. When the Fermi level is close\nto the Dirac point and the surface state dominates the electric conduction,\nsharp increases in resistance with decreasing temperatures were observed\nconcurrently with the magnetic anomalies. Positive-negative magnetoresistance\ncrossovers were observed at the Curie temperature, which seem only to appear\nwhen the sheet resistance exceeds the Mott-Ioffe-Regel limit $h/e^2$. A\ntwo-stage gap-opening process due to magnetic proximity is proposed.",
        "positive": "Spin torque driven dynamics of a coupled two layer structure: interplay\n  between conservative and dissipative coupling: In this manuscript the general concepts of spin wave theory are adapted to\nthe dynamics of a self-polarized system based on two layers coupled via\ninterlayer exchange (conservative coupling) and mutual spin torque (dissipative\ncoupling). An analytical description of the non-linear dynamics is proposed and\nvalidated through numerical simulations. In contrast to the single layer model,\nthe phase equation of the coupled system has a contribution coming from the\ndissipative part of the LLGS equation. It is shown that this is a major\ncontribution to the frequency mandatory to describe well the most basic\nfeatures of the dynamics of coupled systems. Using the proposed model a\nspecific feature of coupled dynamics is addressed: the redshift to blueshift\ntransition observed in the frequency current dependence of this kind of\nexchange coupled systems upon increasing the applied field. It is found that\nthe blueshift regime can only occur in a region of field where the two linear\neigenmodes contribute equally to the steady state mode (i.e. high mode\nhybridization). Finally, a general perturbed Hamiltonian equation for the\ncoupled system is proposed."
    },
    {
        "anchor": "Nanoscale transient polarization gratings: We present the generation of transient polarization gratings at the\nnanoscale, achieved using a tailored accelerator configuration of the FERMI\nfree electron laser. We demonstrate the capabilities of such a transient\npolarization grating by comparing its induced dynamics with the ones triggered\nby a more conventional intensity grating on a thin film ferrimagnetic alloy.\nWhile the signal of the intensity grating is dominated by the thermoelastic\nresponse of the system, such a contribution is suppressed in the case of the\npolarization grating. This exposes helicity-dependent magnetization dynamics\nthat have so-far remained hidden under the large thermally driven response. We\nanticipate nanoscale transient polarization gratings to become useful for the\nstudy of any physical, chemical and biological systems possessing chiral\nsymmetry.",
        "positive": "Effect of polar discontinuity on the growth of LaNiO3/LaAlO3\n  superlattices: We have conducted a detailed microscopic investigation of [LaNiO3(1\nu.c.)/LaAlO3(1 u.c.)]N superlattices grown on (001) SrTiO3 and LaAlO3 to\nexplore the influence of polar mismatch on the resulting electronic and\nstructural properties. Our data demonstrate that the initial growth on the\nnon-polar SrTiO3 surface leads to a rough morphology and unusual 2+ valence of\nNi in the first LaNiO3 layer, which is not observed after growth on the polar\nsurface of LaAlO3. A newly devised model suggests that the polar mismatch can\nbe resolved if the perovskite layers grow with an excess of LaO, which also\naccounts for the observed electronic, chemical, and structural effects."
    },
    {
        "anchor": "Does a dissolution-precipitation mechanism explain concrete creep in\n  moist environments?: Long-term creep (i.e., deformation under sustained load) is a significant\nmaterial response that needs to be accounted for in concrete structural design.\nHowever, the nature and origin of creep remains poorly understood, and\ncontroversial. Here, we propose that concrete creep at RH (relative humidity) >\n50%, but fixed moisture-contents (i.e., basic creep), arises from a\ndissolution-precipitation mechanism, active at nanoscale grain contacts, as is\noften observed in a geological context, e.g., when rocks are exposed to\nsustained loads, in moist environments. Based on micro-indentation and vertical\nscanning interferometry experiments, and molecular dynamics simulations carried\nout on calcium-silicate-hydrates (C-S-H's), the major binding phase in\nconcrete, of different compositions, we show that creep rates are well\ncorrelated to dissolution rates - an observation which supports the\ndissolution-precipitation mechanism as the origin of concrete creep. C-S-H\ncompositions featuring high resistance to dissolution, and hence creep are\nidentified - analysis of which, using topological constraint theory, indicates\nthat these compositions present limited relaxation modes on account of their\noptimally connected (i.e., constrained) atomic networks.",
        "positive": "Chlorine Adsorption on Graphene: Chlorographene: We perform first-principles structure optimization, phonon frequency and\nfinite temperature molecular dynamics calculations based on density functional\ntheory to study the interaction of chlorine atoms with graphene predicting the\nexistence of possible chlorinated graphene derivatives. The bonding of a single\nchlorine atom is ionic through the transfer of charge from graphene to chlorine\nadatom and induces negligible local distortion in the underlying planar\ngraphene. Different from hydrogen and fluorine adatoms, the migration of a\nsingle chlorine adatom on the surface of perfect graphene takes place almost\nwithout barrier. However, the decoration of one surface of graphene with Cl\nadatoms leading to various conformations cannot sustain due to strong Cl-Cl\ninteraction resulting in the desorption through the formation of Cl$_2$\nmolecules. On the contrary, the fully chlorinated graphene, chlorographene CCl,\nwhere single chlorine atoms are bonded alternatingly to each carbon atom from\ndifferent sides of graphene with $sp^3$-type covalent bonds, is buckled. We\nfound that this structure is stable and is a direct band gap semiconductor,\nwhose band gap can be tuned by applied uniform strain. Calculated phonon\ndispersion relation and four Raman-active modes of chlorographene are\ndiscussed."
    },
    {
        "anchor": "Photoelectron spectra of early $3d$-transition metal dioxide cluster\n  anions from $GW$ calculations: Photoelectron spectra of early $3d-$transition metal dioxide anions,\nScO$_{2}^-$, TiO$_{2}^-$, VO$_{2}^-$, CrO$_{2}^-$, MnO$_{2}^-$, are calculated\nusing semilocal and hybrid density functional theory (DFT) and many-body\nperturbation theory within the $GW$ approximation using one-shot perturbative\nand eigenvalue self-consistent formalisms. Different levels of theory are\ncompared with each other and with available photoelectron spectra. We show that\none-shot $GW$ with a PBE0 starting point ($G_0W_0$@PBE0) consistently provides\nvery good agreement for all experimentally measured binding energies (within\n0.1-0.2 eV or less), which we attribute to the success of PBE0 in mitigating\nself-interaction error and providing good quasiparticle wave functions, which\nrenders a first-order perturbative $GW$ correction effective. One-shot $GW$\ncalculations with semilocal exchange in the DFT starting point (e.g.\n$G_0W_0$@PBE) do poorly in predicting electron removal energies by underbinding\norbitals with typical errors near 1.5 eV. Higher amounts of exact exchange\n(e.g. 50%) in the DFT starting point of one-shot $GW$ do not provide very good\nagreement with experiment by overbinding orbitals with typical errors near 0.5\neV. While not as accurate as $G_0W_0$@PBE0, the $G$-only eigenvalue\nself-consistent $GW$ scheme with $W$ fixed to the PBE level ($G_nW_0$@PBE)\nprovides a reasonably predictive level of theory (typical errors near 0.3 eV)\nto describe photoelectron spectra of these $3d-$transition metal dioxide\nanions. Adding eigenvalue self-consistency also in $W$ ($G_nW_n$@PBE), on the\nother hand, worsens the agreement with experiment overall. Our findings on the\nperformance of various $GW$ methods are discussed in the context of our\nprevious studies on other transition metal oxide molecular systems.",
        "positive": "Thermoelectric performance of classical topological insulator nanowires: There is currently substantial effort being invested into creating efficient\nthermoelectric nanowires based on topological insulator chalcogenide-type\nmaterials. A key premise of these efforts is the assumption that the generally\ngood thermoelectric properties that these materials exhibit in bulk form will\ntranslate into similarly good or even better thermoelectric performance of the\nsame materials in nanowire form. Here, we calculate thermoelectric performance\nof topological insulator nanowires based on Bi2Te3, Sb2Te3 and Bi2Se3 as a\nfunction of diameter and Fermi level. We show that the thermoelectric\nperformance of topological insulator nanowires does not derive from the\nproperties of the bulk material in a straightforward way. For all investigated\nsystems the competition between surface states and bulk channel causes a\nsignificant modification of the thermoelectric transport coefficients if the\ndiameter is reduced into the sub-10 um range. Key aspects are that the surface\nand bulk states are optimized at different Fermi levels or have different\npolarity as well as the high surface to volume ratio of the nanowires. This\nlimits the maximum thermoelectric performance of topological insulator\nnanowires and thus their application in efficient thermoelectric devices."
    },
    {
        "anchor": "Ab Initio Study of the Structural Phase Transition in Cubic Pb_3GeTe_4: In the substitutionally disordered narrow-gap semiconductor Pb_{1-x}Ge_xTe, a\nfinite-temperature cubic-rhombohedral transition appears above a critical\nconcentration $x \\approx 0.005$. As a first step towards a first-principles\ninvestigation of this transition in the disordered system, a (hypothetical)\nordered cubic Pb_3GeTe_4 supercell is studied. First principles\ndensity-functional calculations of total energies and linear response functions\nare performed using the conjugate-gradients method with ab initio\npseudopotentials and a plane-wave basis set. Unstable modes in Pb_3GeTe_4 are\nfound, dominated by off-centering of the Ge ions coupled with displacements of\ntheir neighboring Te ions. A model Hamiltonian for this system is constructed\nusing the lattice Wannier function formalism. The parameters for this\nHamiltonian are determined from first principles. The equilibrium\nthermodynamics of the model system is studied via Metropolis Monte Carlo\nsimulations. The calculated transition temperature, T_c, is approximately 620K\nfor the cubic Pb_3GeTe_4 model, compared to the experimental value of T_c\n\\approx 350K for disordered Pb_{0.75}Ge_{0.25}Te. Generalization of this\nanalysis to the disordered Pb_{1-x}Ge_xTe system is discussed.",
        "positive": "Current developments in silicene and germanene: Exploration of the unusual properties of the two-dimensional materials\nsilicene and germanene is a very active research field in recent years. This\narticle therefore reviews the latest developments, focusing both on the\nfundamental materials properties and on possible applications."
    },
    {
        "anchor": "Graphene Nanoribbon as an Elastic Damper: Heterostructures composed of dissimilar two-dimensional nanomaterials can\nhave nontrivial physical and mechanical properties promising for many\napplications. Interestingly, in some cases, it is possible to create\nheterostructures composed of weakly and strongly stretched domains with the\nsame chemical composition, as it has been demonstrated for some polymer chains,\nDNA, and intermetallic nanowires supporting this effect of two-phase\nstretching. These materials at relatively strong tension forces split into\ndomains with smaller and larger tensile strain. Within this region, average\nstrain increases at constant tensile force due to the growth of the domain with\nthe larger strain in the expense of the domain with smaller strain. Here the\ntwo-phase stretching phenomenon is described for graphene nanoribbons with the\nhelp of molecular dynamics simulations. This unprecedented feature of graphene\nrevealed in our study is related to the peculiarities of nucleation and motion\nof the domain walls separating the domains with different elastic strain. It\nturns out that the loading-unloading curves exhibit a hysteresis-like behavior\ndue to the energy dissipation during the domain wall nucleation and motion.\nHere, we originally put forward the idea of implementing graphene nanoribbons\nas elastic dampers, efficiently converting mechanical strain energy into heat\nduring cyclic loading-unloading through elastic extension where domains with\nlarger and smaller strain coexist. Furthermore, in the regime of two-phase\nstretching, graphene nanoribbon is a heterostructure for which the fraction of\ndomains with larger and smaller strain, and consequently its physical and\nmechanical properties, can be tuned in a controllable manner by applying\nelastic strain and/or heat.",
        "positive": "Retrieval of the atomic displacements in the crystal from the coherent\n  x-ray diffraction pattern: We investigate the retrieval of spatially resolved atomic displacements via\nthe phases of the direct(real)-space image reconstructed from the strained\ncrystal's coherent x-ray diffraction pattern. We demonstrate that limiting the\nspatial variation of the first and second order spatial displacement\nderivatives improves convergence of the iterative phase retrieval algorithm for\ndisplacements reconstructions to the true solution. Our approach is exploited\nto retrieve the displacement in a periodic array of silicon lines isolated by\nsilicon dioxide filled trenches."
    },
    {
        "anchor": "Lattice thermal conductivity and elastic modulus of XN4 (X=Be, Mg and\n  Pt) 2D materials using machine learning interatomic potentials: The newly synthesized BeN4 monolayer has introduced a novel group of 2D\nmaterials called nitrogen-rich 2D materials. In the present study, the\nanisotropic mechanical and thermal properties of three members of this group,\nBeN4, MgN4, and PtN4, are investigated. To this end, a machine learning-based\ninteratomic potential (MLIP) is developed on the basis of the moment tensor\npotential (MTP) method and utilized in classical molecular dynamics (MD)\nsimulation. Mechanical properties are calculated by extracting the\nstress-strain curve and thermal properties by non-equilibrium molecular\ndynamics (NEMD) method. Acquired results show the anisotropic elastic modulus\nand lattice thermal conductivity of these materials. Generally, elastic modulus\nand thermal conductivity in the armchair direction are higher than in the\nzigzag direction. Also, the elastic anisotropy is almost constant at every\ntemperature for BeN4 and MgN4, while for PtN4, this parameter is decreased by\nincreasing the temperature. The findings of this research are not only evidence\nof the application of machine learning in MD simulations, but also provide\ninformation on the basic anisotropic mechanical and thermal properties of these\nnewly discovered 2D nanomaterials.",
        "positive": "Effect of induced shape anisotropy on magnetic properties of\n  ferromagnetic cobalt nanocubes: We report on the synthesis of ferromagnetic cobalt nanocubes of various sizes\nusing thermal pyrolysis method and the effect of shape anisotropy on the static\nand dynamic magnetic properties were studied. Shape anisotropy of approximately\n10 % was introduced in nanocubes by making nanodiscs using a linear chain amine\nsurfactant during synthesis process. It has been observed that, ferromagnetism\npersisted above room temperature and a sharp drop in magnetic moment at low\ntemperatures in zero-field cooled magnetization may be associated with the spin\ndisorder due to the effective anisotropy present in the system. Dynamic\nmagnetic properties were studied using RF transverse susceptibility\nmeasurements at different temperatures and the singularities due to anisotropy\nfields were probed at low temperatures. Symmetrically located broad peaks are\nobserved in the frozen state at the effective anisotropy fields and the peak\nstructure is strongly affected by shape anisotropy and temperature.\nIrrespective of size the shape anisotropy gave rise to higher coercive fields\nand larger transverse susceptibility ratio at all temperatures. The role of\nshape anisotropy and the size of the particles on the observed magnetic\nbehaviour were discussed."
    },
    {
        "anchor": "Exchange Bias in Ferromagnetic/Compensated Antiferromagnetic Bilayers: By means of micromagnetic spin dynamics calculations, a quantitative\ncalculation is carried out to explore the mechanism of exchange bias (EB) in\nferromagnetic (FM)/compensated antiferromagnetic (AFM) bilayers. The\nantiferromagnets with low and high Neel temperatures have been both considered,\nand the crossover from negative to positive EB is found only in the case with\nlow Neel temperature. We propose that the mechanism of EB in FM/compensated AFM\nbilayers is due to the symmetry broken of AFM that yields some net\nferromagnetic components.",
        "positive": "Atomistic Mechanism of the Nucleation of Methylammonium Lead Iodide\n  Perovskite from Solution: In the ongoing intense quest to increase the photoconversion efficiencies of\nlead halide perovskites, it has become evident that optimizing the morphology\nof the material is essential to achieve high peformance. Despite the fact that\nnucleation plays a key role in controlling the crystal morphology, very little\nis known about the nucleation and crystal growth processes. Here, we perform\nmetadynamics simulations of nucleation of methylammonium lead triiodide (MAPI)\nin order to unravel the atomistic details of perovskite crystallization from a\n$\\gamma$-butyrolactone solution. The metadynamics trajectories show that the\nnucleation process takes place in several stages. Initially, dense amorphous\nclusters mainly consisting of lead and iodide appear from the homogeneous\nsolution. These clusters evolve into lead iodide (PbI$_{2}$) like structures.\nSubsequently, methylammonium (MA$^{+}$) ions diffuse into this PbI$_{2}$-like\naggregates triggering the transformation into a perovskite crystal through a\nsolid-solid transformation. Demonstrating the crucial role of the monovalent\ncations in crystallization, our simulations provide key insights into the\nevolution of the perovskite microstructure which is essential to make\nhigh-quality perovskite based solar cells and optoelectronics."
    },
    {
        "anchor": "Symmetry of superconducting correlations in displaced bilayers of\n  graphene: Using a Green's function approach, we study phonon-mediated superconducting\npairing symmetries that may arise in bilayer graphene where the monolayers are\ndisplaced in-plane with respect to each other. We consider a generic coupling\npotential between the displaced graphene monolayers, which is applicable to\nboth shifted and commensurate twisted graphene layers; study intralayer and\ninterlayer phonon-mediated BCS pairings; and investigate AA and AB(AC) stacking\norders. Our findings demonstrate that at the charge neutrality point, the\ndominant pairings in both AA and AB stackings with intralayer and interlayer\nelectron-electron couplings can have even-parity $s$-wave class and odd-parity\n$p$-wave class of symmetries with the possibility of invoking equal-pseudospin\nand odd-frequency pair correlations. At a finite doping, however, the AB (and\nequivalently AC) stacking can develop pseudospin-singlet and pseudospin-triplet\n$d$-wave symmetry, in addition to $s$-wave, $p$-wave, $f$-wave, and their\ncombinations, while the AA stacking order, similar to the undoped case, is\nunable to host the $d$-wave symmetry. When we introduce a generic coupling\npotential, applicable to commensurate twisted and shifted bilayers of graphene,\n$d$-wave symmetry can also appear at the charge neutrality point. Inspired by a\nrecent experiment where two phonon modes were observed in a twisted bilayer\ngraphene, we also discuss the possibility of the existence of two-gap\nsuperconductivity, where the intralayer and interlayer phonon-mediated BCS\npicture is responsible for superconductivity. These analyses may provide a\nuseful tool in determining the superconducting pairing symmetries and mechanism\nin bilayer graphene systems.",
        "positive": "Metastability of Mn$^{3+}$ in ZnO driven by strong $d$(Mn) intrashell\n  Coulomb repulsion: experiment and theory: Depopulation of the Mn$^{2+}$ state in ZnO:Mn upon illumination, monitored by\nquenching of the Mn$^{2+}$ EPR signal intensity, was observed at temperatures\nbelow 80~K. Mn$^{2+}$ photoquenching is shown to result from the Mn$^{2+}$\n$\\to$ Mn$^{3+}$ ionization transition, promoting one electron to the conduction\nband. Temperature dependence of this process indicates the existence of an\nenergy barrier for electron recapture of the order of 1~meV. GGA$+U$\ncalculations show that after ionization of Mn$^{2+}$ a moderate breathing\nlattice relaxation in the 3+ charge state occurs, which increases energies of\n$d$(Mn) levels. At its equilibrium atomic configuration, Mn$^{3+}$ is\nmetastable since the direct capture of photo-electron is not possible. The\nmetastability is mainly driven by the strong intra-shell Coulomb repulsion\nbetween $d$(Mn) electrons. Both the estimated barrier for electron capture and\nthe photoionization energy are in good agreement with the experimental values."
    },
    {
        "anchor": "Phase diagram of magnetic domain walls in spin valve nano-stripes: We investigate numerically the transverse versus vortex phase diagram of\nhead-to-head domain walls in Co/Cu/Py spin valve nano-stripes (Py: Permalloy),\nin which the Co layer is mostly single domain while the Py layer hosts the\ndomain wall. The range of stability of the transverse wall is shifted towards\nlarger thickness compared to single Py layers, due to a magnetostatic screening\neffect between the two layers. An approached analytical scaling law is derived,\nwhich reproduces faithfully the phase diagram.",
        "positive": "Stability of a Rolled-Up Conformation State for Two-Dimensional\n  Materials in Aqueous Solutions: Two-dimensional (2D) materials can roll up, forming stable scrolls under\nsuitable conditions. However, the great diversity of materials and fabrication\ntechniques has resulted in a huge parameter space significantly complicating\nthe theoretical description of scrolls. In this Letter, we describe a universal\nbinding energy of scrolls determined solely by their material parameters, the\nbending stiffness, and the Hamaker coefficient. Aiming to predict the stability\nof functionalized scrolls in water solutions, we consider the electrostatic\ndouble-layer repulsion force that may overcome the binding energy and flatten\nthe scrolls. Our predictions are represented as comprehensive maps indicating\nthe stable and unstable regions of a rolled-up conformation state in the space\nof material and external parameters. While focusing mostly on functionalized\ngraphene in this work, our approach is applicable to the whole range of 2D\nmaterials able to form scrolls."
    },
    {
        "anchor": "Near room-temperature colossal magnetodielectricity and multiglass\n  properties in partially-disordered La2NiMnO6: We report magnetic, dielectric and magnetodielectric responses of pure\nmonoclinic bulk phase of partially-disordered La2NiMnO6, exhibiting a spectrum\nof unusual properties and establish that this system intrinsically is a true\nmultiglass with a large magnetodielectric coupling (8-20%) over a wide range of\ntemperatures (150 - 300 K). Specifically, our results establish a unique way to\nobtain colossal magnetodielectricity, independent of any striction effects, by\nengineering the asymmetric hopping contribution to the dielectric constant via\nthe tuning of the relative spin orientations between neighboring magnetic ions\nin a transition metal oxide system. We discuss the role of anti-site (Ni-Mn)\ndisorder in emergence of these unusual properties.",
        "positive": "On the polytypism of layered $\\textit{MX}_2$ materials: We revisit the problem of polytypism in layered $\\textit{MX}_2$ materials,\nwith a view to reinterpreting the phase space accessible to this family. Our\nstarting point is to develop a simple, constructive and compact label for the\nmost commonly observed stacking arrangements that is similar to the Glazer\nnotation used to label tilt systems in perovskites. The key advantage of this\nlabel in the context of $\\textit{MX}_2$ systems is that it contains sufficient\ninformation to generate the corresponding stacking sequences uniquely. Using a\nrelated approach, we generate a Cartesian representation of the phase space\ncontaining all possible $\\textit{MX}_2$ polytypes, with the most common\nstructures appearing as limiting cases. We argue that variation in (e.g.\ncomposition, or temperature, or pressure) may allow navigation of this phase\nspace along continuous paths. This interpretation is shown to be consistent\nwith the structural evolution of stacking-faulted $\\textit{MX}_2$ systems as a\nfunction of temperature and composition. Our study highlights the potential for\ncontrolling composition/structure/property relationships amongst layered\n$\\textit{MX}_2$ materials in ways that might not previously have been obvious."
    },
    {
        "anchor": "Discovery of Weyl semimetal state violating Lorentz invariance in MoTe2: A new type of Weyl semimetal state, in which the energy values of Weyl nodes\nare not the local extrema, has been theoretically proposed recently, namely\ntype II Weyl semimetal. Distinguished from type I semimetal (e.g. TaAs), the\nFermi surfaces in a type II Weyl semimetal consist of a pair of electron and\nhole pockets touching at the Weyl node. In addition, Weyl fermions in type II\nWeyl semimetals violate Lorentz invariance. Due to these qualitative\ndifferences distinct spectroscopy and magnetotransport properties are expected\nin type II Weyl semimetals. Here, we present the direct observation of the\nFermi arc states in MoTe2 by using angle resolved photoemission spectroscopy.\nTwo arc states are identified for each pair of Weyl nodes whoes surface\nprojections of them possess single topological charge, which is a unique\nproperty for type II Weyl semimetals. The experimentally determined Fermi arcs\nare consistent with our first principle calculations. Our results unambiguously\nestablish that MoTe2 is a type II Weyl semimetal, which serves as a great test\nbed to investigate the phenomena of new type of Weyl fermions with Lorentz\ninvariance violated.",
        "positive": "Hydrodynamic approximation for the nonlinear response of a metal surface: We present semi-classical and quantized hydrodynamic models to obtain the\nquadratic electronic response of a plane-bounded electron gas. Explicit\nexpressions for the dynamic image potential experienced by charged particles\nmoving near a jellium surface are derived, up to third order in the projectile\ncharge. These expressions are employed to compute the image potential at all\ndistances outside the surface. Though nonlinear corrections are found to be\nmore important far inside the solid than outside, our results indicate that the\nnonlinear image potential is enhanced with respect to the linear image\npotential by a factor that is for Al as large as $\\sim 1.15$ near the surface\nin the case of a stationary particle ($v\\to 0$) with positive unit charge $e$."
    },
    {
        "anchor": "Extraordinary Tunneling Magnetoresistance in Antiferromagnetic Tunnel\n  Junctions with Antiperovskite Electrodes: Recent theoretical predictions and experimental demonstrations of a large\ntunneling magnetoresistance (TMR) effect in antiferromagnetic (AFM) tunnel\njunctions (AFMTJs) offer a new paradigm for information technologies where the\nAFM N\\`eel vector serves as a state variable. A large TMR is beneficial for the\napplications. Here, we predict the emergence of an extraordinary TMR (ETMR)\neffect in AFMTJs utilizing noncollinear AFM antiperovskite XNMn$_{3}$ (X = Ga,\nSn,...) electrodes and a perovskite oxide ATiO$_{3}$ (A = Sr, Ba,...) barrier\nlayer. The ETMR effect stems from the perfectly spin-polarized electronic\nstates in the AFM antiperovskites that can efficiently tunnel through the\nlow-decay-rate evanescent states of the perovskite oxide while preserving their\nspin state. Using an GaNMn$_{3}$/SrTiO$_{3}$/GaNMn$_{3}$ (001) AFMTJ as a\nrepresentative example, we demonstrate a giant TMR ratio exceeding $10^{4}$%\nand originating from the ETMR effect. These results are promising for the\nefficient detection and control of the N\\`eel vector in AFM spintronics.",
        "positive": "Strongly enhanced magnetic moments in ferromagnetic\n  FeMnP$_{0.50}$Si$_{0.50}$: The compound FeMnP$_{0.50}$Si$_{0.50}$ has been studied by magnetic\nmeasurements, M\\\"ossbauer spectroscopy and electronic structure and total\nenergy calculations. An unexpected high magnetic hyperfine field for Fe atoms\nlocated at the tetrahedral Me(1) site in the Fe$_2$P structure is found. The\nsaturation moment derived from magnetic measurements corresponds to 4.4\n$\\mu_B$/f.u. at low temperatures, a value substantially higher than previously\nreported, but in accord with the results from our electron structure\ncalculations. This high saturation moment, a first order nature of the\nferromagnetic transition and a tunable transition temperature make the\nFe$_{2-x}$Mn$_{x}$P$_{1-y}$Si$y$ system promising for magnetocaloric\napplications."
    },
    {
        "anchor": "X-ray absorption spectra at the Ca-L$_{2,3}$-edge calculated within\n  multi-channel multiple scattering theory: We report a new theoretical method for X-ray absorption spectroscopy (XAS) in\ncondensed matter which is based on the multi-channel multiple scattering theory\nof Natoli et al. and the eigen-channel R-matrix method. While the highly\nflexible real-space multiple scattering (RSMS) method guarantees a precise\ndescription of the single-electron part of the problem, multiplet-like electron\ncorrelation effects between the photo-electron and localized electrons can be\ntaken account for in a configuration interaction scheme. For the case where\ncorrelation effects are limited to the absorber atom, a technique for the\nsolution of the equations is devised, which requires only little more\ncomputation time than the normal RSMS method for XAS. The new method is\ndescribed and an application to XAS at the Ca $L_{2,3}$-edge in bulk Ca, CaO\nand CaF$_2$ is presented.",
        "positive": "Improvement in the Performance and Efficiency on Self-Deficient\n  CaTiO$_3$: Towards Sustainable and Affordable New-Generation Solar Cells: Thin films of pure and self-deficient calcium titanites i.e., CaTiO$_3$,\nCa$_{1-\\alpha}$TiO$_3$, CaTi$_{1-\\beta}$O$_3$ and CaTiO$_{3-\\gamma}$ have been\ndeposited on ITO substrate using dip coating method. X-ray diffraction and\nScanning electron Microscopy (SEM) analysis confirm the structural and\nmorphology of all deposited thin films. Photocurrent measurement has been done,\nand it is observed that during the incidence of UV light on the as-prepared\ndevice (i.e., in the \"ON\" state), a significant increase in photocurrent (IUV)\nat zero voltage was observed in case of O deficient CaTiO$_3$, while in case of\nTi and Ca deficient thin films smaller values of photocurrents were seen.\nResponsivity and detectivity of deposited thin films of all self-deficient\nCaTiO3 were found to be maximum in the UV region while they also showed smaller\ncontributions in the visible range possibly due to the presence of\nself-deficiency. The self-deficient sample exhibits lower resistance (higher\nrecombination rate) than the pure sample at low voltage, but at higher voltage,\nit is almost identical. Furthermore, theoretical calculations have been\nperformed using the first-principles density-functional theory to validate the\nexperimental findings on self-deficient CaTiO$_3$. Incident-photon-to-current\nefficiency (IPCE) and current density have also been measured for all deficient\nCaTiO$_3$ samples. Maximum IPCE have been found in the range 25%-28% for Ti and\nO deficient samples in the UV range (280- 400 nm). We argue that\nfirst-principles DFT calculations combined with the experimental measurements\non self-deficient CaTiO$_3$ thin films offer a reliable way to enhance the\nperformance of perovskite-based solar devices."
    },
    {
        "anchor": "First-Principles Studies of Local Order in Relaxor Ferroelectrics: A key to optimizing the growth of the new single-crystal relaxor\nferroelectrics is resolving basic questions concerning their structural\nproperties and energetics. We report on initial first-principles total energy\nand force calculations, examining the energetics of local order in PZN type\nrelaxors.",
        "positive": "Temperature-dependent pressure-induced softening in Zn(CN)$_{2}$: We investigate the temperature dependence of the pressure-induced softening\nin the negative thermal expansion material Zn(CN)$_2$ using neutron powder\ndiffraction and molecular dynamics simulations. Both the simulation and\nexperiment show that the pressure-induced softening only occurs above a minimum\ntemperature and also weakens at high temperatures."
    },
    {
        "anchor": "Oxygen vacancy mediated cubic phase stabilization at room temperature in\n  pure nano-crystalline Zirconia films: A combined experimental and\n  first-principles based investigation: We report the formation of cubic phase, under ambient conditions, in thin\nfilms of Zirconia synthesized by electron beam evaporation technique. The\nstabilization of the cubic phase was achieved without the use of chemical\nstabilizers and/or concurrent ion beam bombardment. Films of two different\nthickness (660 nm, 140 nm) were deposited. The 660 nm and 140 nm films were\nfound to be stoichiometric (ZrO2) and off-stoichiometric (ZrO1.7) respectively\nby Resonant Rutherford back-scattering spectroscopy. While the 660 nm\nas-deposited films were in the cubic phase, as indicated by X-ray diffraction\nand Raman spectroscopy measurements, the 140 nm as-deposited films were\namorphous and the transformation to cubic phase was obtained after thermal\nannealing. Extended X-ray absorption fine structure measurements revealed the\nexistence of Oxygen vacancies in the local structure surrounding Zirconium for\nall films. However, the amount of these Oxygen vacancies was found to be\nsignificantly higher for the amorphous films as compared to the films in the\ncubic phase (both 660 nm as-deposited and 140 nm annealed films). The cubic\nphase stabilization is explained on the basis of suppression of the soft X2-\nmode of vibration of the Oxygen sub-lattice due to the presence of the Oxygen\nvacancies. Our first-principles modeling under the framework of density\nfunctional theory shows that the cubic structure with Oxygen vacancies is\nindeed more stable at ambient conditions than its pristine (without vacancies)\ncounterpart. The requirement of a critical amount of these vacancies for the\nstabilization of the cubic phase is also discussed.",
        "positive": "Parametric amplification of optical phonons: Amplification of light through stimulated emission or nonlinear optical\ninteractions has had a transformative impact on modern science and technology.\nThe amplification of other bosonic excitations, like phonons in solids, is\nlikely to open up new remarkable physical phenomena. Here, we report on an\nexperimental demonstration of optical phonon amplification. A coherent\nmid-infrared optical field is used to drive large amplitude oscillations of the\nSi-C stretching mode in silicon carbide. Upon nonlinear phonon excitation, a\nsecond probe pulse experiences parametric optical gain at all wavelengths\nthroughout the reststrahlen band, which reflects the amplification of\noptical-phonon fluctuations. Starting from first principle calculations, we\nshow that the high-frequency dielectric permittivity and the phonon oscillator\nstrength depend quadratically on the lattice coordinate. In the experimental\nconditions explored here, these oscillate then at twice the frequency of the\noptical field and provide a parametric drive for lattice fluctuations.\nParametric gain in phononic four wave mixing is a generic mechanism that can be\nextended to all polar modes of solids, as a new means to control the kinetics\nof phase transitions, to amplify many body interactions or to control\nphonon-polariton waves."
    },
    {
        "anchor": "Probing angle dependent thermal conductivity in twisted bilayer MoSe2: Twisted bilayer (t-BL) transition metal dichalcogenides (TMDCs) attracted\nconsiderable attention in recent years due to their distinctive electronic\nproperties, which arise due to the moire superlattices that lead to the\nemergence of flat bands and correlated electron phenomena. Also, these\nmaterials can exhibit interesting thermal properties, including a reduction in\nthermal conductivity. In this article, we report the thermal conductivity of\nmonolayer (1L) and t-BL MoSe2 at some specific twist angles around two\nsymmetric stacking AB (0 degree) and AB' (60 degree) and one intermediate angle\n31 (degree) using the optothermal Raman technique. The observed thermal\nconductivity values are found to be 13, 23, and 30 W m-1K-1 for twist angle =\n58 (degree), 31 (degree) and, 3 (degree) respectively, which is well supported\nby our first-principles calculation results. The reduction in thermal\nconductivity in t-BL MoSe2 compared to monolayer (38 W m-1K-1) can be explained\nby the occurrence of phonon scattering caused by the formation of a moire\nsuper-lattice. Herein, the emergence of multiple folded phonon branches and\nmodification in the Brillouin zone caused by in-plane rotation are also\naccountable for the decrease in thermal conductivity observed in t-BL MoSe2.\nThe theoretical phonon lifetime study and electron localization function (ELF)\nanalysis further reveals the origin of angle-dependent thermal conductivity in\nt-BL MoSe2. This work paves the way towards tuning the angle-dependent thermal\nconductivity for any bilayer TMDCs system.",
        "positive": "Influence of a Transport Current on Magnetic Anisotropy in Gyrotropic\n  Ferromagnets: Current-induced torques are commonly used to manipulate non-collinear\nmagnetization configurations. In this article we discuss current-induced\ntorques present in a certain class of collinear magnetic systems, relating them\nto current-induced changes in magnetic anisotropy energy. We present a\nquantitative estimate of their characteristics in uniform strained\nferromagnetic (Ga,Mn)As."
    },
    {
        "anchor": "A Reactive Molecular Dynamics Study of Hydrogenation on Diamond Surfaces: Hydrogenated diamond has been regarded as a promising material in electronic\ndevice applications, especially in field-effect transistors (FETs). However,\nthe quality of diamond hydrogenation has not yet been established, nor has the\nspecific orientation that would provide the optimum hydrogen coverage. In\naddition, most theoretical work in the literature use models with 100%\nhydrogenated diamond surfaces to study electronic properties, which is far from\nthe experimentally observed hydrogen coverage. In this work, we have carried\nout a detailed study using fully atomistic reactive molecular dynamics (MD)\nsimulations on low indices diamond surfaces i.e. (001), (013), (110), (113) and\n(111) to evaluate the quality and hydrogenation thresholds on different diamond\nsurfaces and their possible effects on electronic properties. Our simulation\nresults indicate that the 100% surface hydrogenation in these surfaces is hard\nto achieve because of the steric repulsion between the terminated hydrogen\natoms. Among all the considered surfaces, the (001), (110), and (113) surfaces\nincorporate a larger number of hydrogen atoms and passivate the surface\ndangling bonds. Our results on hydrogen stability also suggest that these\nsurfaces with optimum hydrogen coverage are robust under extreme conditions and\ncould provide homogeneous p-type surface conductivity in the diamond surfaces,\na key requirement for high-field, high-frequency device applications.",
        "positive": "Improving Reproducibility of Sputter Deposited Ferroelectric Wurtzite\n  Al0.6Sc0.4N Films using In-situ Optical Emission Spectrometry: High-Sc Al1-xScxN thin films are of tremendous interest because of their\nattractive piezoelectric and ferroelectric properties, but overall film quality\nand reproducibility are widely reported to suffer as x increases. In this\nstudy, we correlate the structure and electrical properties of Al0.6Sc0.4N with\nin-situ observations of glow discharge optical emission during growth. This\nin-situ technique uses changes in the Ar(I) and N2(I) emission lines of the\nglow discharge during growth to identify films that subsequently exhibit\nunacceptable structural and electrical performance. We show that a steady\ndeposition throughout film growth produces ferroelectric Al0.6Sc0.4N with a\nreversible 80 {\\mu}C cm-1 polarization and 3.1 MV cm-1 coercive field. In other\nfilms deposited using identical settings, fluctuations in both Ar(I) and N2(I)\nline intensities correspond to decreased wurtzite phase purity, nm-scale\nchanges to the film microstructure, and a non-ferroelectric response. These\nresults illustrate the power of optical emission spectroscopy for tracking\nchanges when fabricating process-sensitive samples such as high-Sc Al1-xScxN\nfilms."
    },
    {
        "anchor": "Porous Structured Au Colloids: Insights in to Morphology, Optical and\n  Antimicrobial Activity: Porous structured Au colloids have been prepared from bulk nanoporous Au by\nmeans of an element dissociation method. The microscopic techniques (scanning\nelectron microscope and atomic force microscope), UV-Vis spectroscopy and zone\ndiffusion method have been employed to study their morphology, optical property\nand anti-microbial activity against Gram-positive and Gram-negative bacterial\nstrains, respectively. It is shown that the porous structured Au colloidal\nsuspension exhibit excellent optical and antimicrobial properties. The\nnoticeable features present in the optical studies are two Plasmon resonance\npeaks at 477 and 546 nm with overlapping of these peaks at a wavelength of 520\nnm. The morphology studies by SEM and AFM indicate that the Au colloids are rod\nshaped with an assembly of skeletal pore and ligament structure. The analysis\nof the antimicrobial activity testing reveals that the porous structured Au\ncolloids have greater inhibitory effect against the tested Gram-positive and\nGram-negative bacterial strains.",
        "positive": "Theoretical study of the stable states of small carbon clusters Cn (n =\n  2-10): Both even- and odd-numbered neutral carbon clusters Cn (n = 2-10) are\nsystematically studied using the energy minimization method and the modified\nBrenner potential for the carbon-carbon interactions. Many stable\nconfigurations were found and several new isomers are predicted. For the lowest\nenergy stable configurations we obtained their binding energies and bond\nlengths. We found that for n < 6 the linear isomer is the most stable one while\nfor n > 5 the monocyclic isomer becomes the most stable. The latter was found\nto be regular for all studied clusters. The dependence of the binding energy\nfor linear and cyclic clusters versus the cluster size n (n = 2-10) is found to\nbe in good agreement with several previous calculations, in particular with ab\ninitio calculations as well as with experimental data for n = 2-5."
    },
    {
        "anchor": "Defects in Graphene-Based Twisted Nanoribbons: Structural, Electronic\n  and Optical Properties: We present some computational simulations of graphene-based nanoribbons with\na number of half-twists varying from 0 to 4 and two types of defects obtained\nby removing a single carbon atom from two different sites. Optimized geometries\nare found by using a mix of classical-quantum semiempirical computations.\nAccording with the simulations results, the local curvature of the nanoribbons\nincreases at the defect sites, specially for a higher number of half-twists.\nThe HOMO-LUMO energy gap of the nanostructures has significant variation when\nthe number of half-twists increases for the defective nanoribbons. At the\nquantum semiempirical level, the first optically active transitions and\noscillator strengths are calculated using the full configuration interaction\n(CI) framework, and the optical absorption in the UV/Visible range (electronic\ntransitions) and in the infrared (vibrational transitions) are achieved.\nDistinct nanoribbons show unique spectral signatures in the UV/Visible range,\nwith the first absorption peaks in wavelengths ranging from the orange to the\nviolet. Strong absorption is observed in the ultraviolet region, although\ndifferences in their infrared spectra are hardly discernible.",
        "positive": "Effect of Piezoelectric Polarization on Phonon group velocity in\n  Wurtzite Nitrides: We have investigated the effect of piezoelectric (PZ) polarization property\non group velocity of phonons in binary as well as in ternary wurtzite nitrides.\nIt is found that with the presence of PZ polarization property, the phonon\ngroup velocity is modified. The change in phonon group velocity due to PZ\npolarization effect directly depends on piezoelectric tensor value. Using\ndifferent piezoelectric tensor values recommended by different workers in the\nliterature, percent change in group velocities of phonons has been estimated.\nThe Debye temperatures and frequencies of binary nitrides GaN, AlN and InN are\nalso calculated using the modified group velocities. For ternary nitrides\nAlxGa(1-x)N, InxGa(1-x)N and InxAl(1-x)N, the phonon group velocities have been\ncalculated as a functions of composition. A small positive bowing is observed\nin phonon group velocities of ternary alloys. Percent variations in phonon\ngroup velocities are also calculated for a straightforward comparison among\nternary nitrides. The results are expected to show a change in phonon\nrelaxation rates and thermal conductivity of III-nitrides when piezoelectric\npolarization property is taken into account."
    },
    {
        "anchor": "Electronic Structure and Optical Properties of Monolayer $ReS_2$ with\n  Defect Controlled by Strain Engineering: By using first-principles calculations, we investigated the monolayer $ReS_2$\nwith vacancies under strain engineering, specifically focusing on its energy of\nformation, band gap, electron density of states, effective mass and optical\nproperties. The calculated results disclose that S4 defect is more likely to\nform than other kinds of vacancies. Asymmetric deformation induced by strain\nmakes its band structure transformation from direct band gap to indirect band\ngap. The analysis of the partial density of states indicates that the Re-d,\nRe-p and S-d orbitals are the major components of the defect states, being\ndifferent from $MoS_2$, the defect states locate both above and below the Fermi\nlevel. Moreover, the effective mass was sensitive and anisotropic under the\nexternal strain. The reflection spectrum can be greatly tuned by the external\nstrains, which indicates that the ReS2 monolayer has promising applications in\nnanoscale strain sensor and conductance-switch FETs.",
        "positive": "Flipping growth orientation of nanographitic structures by plasma\n  enhanced chemical vapor deposition: Nanographitic structures (NGSs) with multitude of morphological features are\ngrown on SiO2/Si substrates by electron cyclotron resonance - plasma enhanced\nchemical vapor deposition (ECR-PECVD). CH4 is used as source gas with Ar and H2\nas dilutants. Field emission scanning electron microscopy, high resolution\ntransmission electron microscopy (HRTEM) and Raman spectroscopy are used to\nstudy the structural and morphological features of the grown films. Herein, we\ndemonstrate, how the morphology can be tuned from planar to vertical structure\nusing single control parameter namely, dilution of CH4 with Ar and/or H2. Our\nresults show that the competitive growth and etching processes dictate the\nmorphology of the NGSs. While Ar-rich composition favors vertically oriented\ngraphene nanosheets, H2-rich composition aids growth of planar films. Raman\nanalysis reveals dilution of CH4 with either Ar or H2 or in combination helps\nto improve the structural quality of the films. Line shape analysis of Raman 2D\nband shows nearly symmetric Lorentzian profile which confirms the turbostratic\nnature of the grown NGSs. Further, this aspect is elucidated by HRTEM studies\nby observing elliptical diffraction pattern. Based on these experiments, a\ncomprehensive understanding is obtained on the growth and structural properties\nof NGSs grown over a wide range of feedstock compositions."
    },
    {
        "anchor": "Magnetic ordering and fluctuation in kagome lattice antiferromagnets, Fe\n  and Cr jarosites: Jarosite family compounds, KFe_3(OH)_6(SO_4)_2, (abbreviate Fe jarosite), and\nKCr_3(OH)_6(SO_4)_2, (Cr jarosite), are typical examples of the Heisenberg\nantiferromagnet on the kagome lattice and have been investigated by means of\nmagnetization and NMR experiments. The susceptibility of Cr jarosite deviates\nfrom Curie-Weiss law due to the short-range spin correlation below about 150 K\nand shows the magnetic transition at 4.2 K, while Fe jarosite has the\ntransition at 65 K. The susceptibility data fit well with the calculated one on\nthe high temperature expansion for the Heisenberg antiferromagnet on the kagome\nlattice. The values of exchange interaction of Cr jarosite and Fe jarosite are\nderived to be J_Cr = 4.9 K and J_Fe = 23 K, respectively. The 1H-NMR spectra of\nFe jarosite suggest that the ordered spin structure is the q = 0 type with\npositive chirality of the 120 degrees configuration. The transition is caused\nby a weak single-ion type anisotropy. The spin-lattice relaxation rate, 1/T_1,\nof Fe jarosite in the ordered phase decreases sharply with lowering the\ntemperature and can be well explained by the two-magnon process of spin wave\nwith the anisotropy.",
        "positive": "Efficient ionization of two dimensional excitons by intense single cycle\n  terahertz pulses: External electric fields are highly attractive for dynamical manipulation of\nexcitons in two-dimensional materials. Here, we theoretically study the\nionization of excitons in monolayer transition metal dichalcogenides (TMDs) by\nintense pulsed electric fields in the terahertz (THz) regime. We find that THz\npulses with realistic field strengths are capable of ionizing a significant\nfraction of photogenerated excitons in TMDs into free charge carriers. Short\nTHz pulses are therefore an efficient, non-invasive method of dynamically\ncontrolling the free carrier concentration in monolayer TMDs, which is useful\nfor applications such as THz modulators. We further demonstrate that exciton\nionization probabilities should be experimentally measurable by comparing free\ncarrier absorption before and after the THz pulse. Detailed results are\nprovided for different TMDs in various dielectric environments."
    },
    {
        "anchor": "Energetics of H$_2$ clusters from density functional and coupled cluster\n  theories: We use coupled-cluster quantum chemical methods to calculate the energetics\nof molecular clusters cut out of periodic molecular hydrogen structures that\nmodel observed phases of solid hydrogen. The hydrogen structures are obtained\nfrom Kohn-Sham density functional theory (DFT) calculations at pressures of\n150, 250 and 350 GPa, which are within the pressure range in which phases II,\nIII and IV are found to be stable. The calculated deviations in the DFT\nenergies from the coupled-cluster data are reported for different functionals,\nand optimized functionals are generated which provide reduced errors. We give\nrecommendations for semi-local and hybrid density functionals that are expected\nto accurately describe hydrogen at high pressures.",
        "positive": "Origin of high hardness and optoelectronic and thermo-physical\n  properties of boron-rich compounds B6X (X = S, Se): a comprehensive study via\n  DFT approach: In the present study, the structural and hitherto uninvestigated mechanical\n(elastic stiffness constants, machinability index, Cauchy pressure, anisotropy\nindices, brittleness/ductility, Poissons ratio), electronic, optical, and\nthermodynamic properties of novel boron-rich compounds B6X (X = S, Se) have\nbeen explored using density functional theory. The estimated structural lattice\nparameters were consistent with the prior report. The mechanical and dynamical\nstability of these compounds have been established theoretically. The materials\nare brittle in nature and elastically anisotropic. The value of fracture\ntoughness, KIC for the B6S and B6Se are ~ 2.07 MPam0.5, evaluating the\nresistance to limit the crack propagation inside the materials. Both B6S and\nB6Se compounds possess high hardness values in the range 31-35 GPa, and have\nthe potential to be prominent members of the class of hard compounds. Strong\ncovalent bonding and sharp peak at low energy below the Fermi level confirmed\nby partial density of states (PDOS) resulted in the high hardness. The profile\nof band structure, as well as DOS, assesses the indirect semiconducting nature\nof the titled compounds. The comparatively high value of Debye temperature\n({\\Theta}D), minimum thermal conductivity (Kmin), lattice thermal conductivity\n(kph), low thermal expansion coefficient, and low density suggest that both\nboron-rich chalcogenides might be used as thermal management materials. Large\nabsorption capacities in the mid ultraviolet region (3.2-15 eV) of the studied\nmaterials and low reflectivity (~16 %) are significantly noted. Such favorable\nfeatures give promise to the compounds under investigation to be used in UV\nsurface-disinfection devices as well as medical sterilizer equipment\napplications. Excellent correlations are found among all the studied physical\nproperties of these compounds."
    },
    {
        "anchor": "Gold Clusters Sliding on Graphite: a Possible Quartz Crystal\n  Microbalance Experiment?: A large measured 2D diffusion coefficient of gold nanoclusters on graphite\nhas been known experimentally and theoretically for about a decade. When\nsubjected to a lateral force, these clusters should slide with an amount of\nfriction that could be measured. We examine the hypothetical possibility to\nmeasure by Quartz Crystal Microbalance (QCM) the phononic sliding friction of\ngold clusters in the size range around 250 atoms on a graphite substrate\nbetween 300 and 600 K. Assuming the validity of Einstein's relations of\nordinary Brownian motion and making use of the experimentally available\nactivated behavior of the diffusion coefficients, we can predict the sliding\nfriction and slip times as a function of temperature. It is found that a\nprototypical deposited gold cluster could yield slip times in the standard\nmeasurable size of 10^(-9) sec for temperatures around 450-500 K, or 200 C.\nSince gold nanoclusters may also melt around these temperatures, QCM would\noffer the additional chance to observe this phenomenon through a frictional\nchange.",
        "positive": "Electrical transport crossover and large magnetoresistance in selenium\n  deficient van der Waals HfSe2-x: Transition metal dichalcogenides have received much attention in the past\ndecade not only due to the new fundamental physics, but also due to the\nemergent applications in these materials. Currently chalcogenide deficiencies\nin TMDs are commonly believed either during the high temperature growth\nprocedure or in the nanofabrication process resulting significant changes of\ntheir reported physical properties in the literature. Here we perform a\nsystematic study involving pristine stochiometric HfSe2, Se deficient HfSe1.9\nand HfSe1.8. Stochiometric HfSe2 transport results show semiconducting behavior\nwith a gap of 1.1eV. Annealing HfSe2 under high vacuum at room temperature\ncauses the Se loss resulting in HfSe1.9, which shows unconventionally large\nmagnetoresistivity following the extended Kohler's rule at low temperatures\nbelow 50 K. Moreover, a clear electrical resistivity crossover, mimicking the\nmetal-insulator transition, is observed in the HfSe1.9 single crystal. Further\nincreasing the degree of deficiency in HfSe1.8 results in complete metallic\nelectrical transport at all temperatures down to 2K. Such a drastic difference\nin the transport behaviors of stoichiometric and Se-deficient HfSe2 further\nemphasizes that defect control and engineering could be an effective method\nthat could be used to tailor the electronic structure of 2D materials,\npotentially unlock new states of matter, or even discover new materials."
    },
    {
        "anchor": "Topological Luttinger semimetallic phase accompanied with surface states\n  realized in silicon: By means of systematically first-principles calculations and model analysis,\na complete phase diagram of the body-centered silicon(BC8-Si) via lattice\nconstant a and internal atomic coordinate x is explored, which demonstrates\nthat BC8-Si is a topological Luttinger semimetal(LSM) accompanied with\ntopologically nontrivial surface states, and the electronic properties of\nBC8-Si can be further tuned to a normal insulator or topological Dirac\nsemimetal by very tiny changing of a and x. These results successfully explain\nthe contradictory transport reports of BC8-Si. More importantly, the\ntopological surface states in the LSM phase fill in the gap between the\ntopological matters and silicon, which provide an opportunity to integrate the\ntopological quantum devices and silicon chips together.",
        "positive": "Rational Design of Efficient Defect-Based Quantum Emitters: Single-photon emitters are an essential component of quantum networks, and\ndefects or impurities in semiconductors are a promising platform to realize\nsuch quantum emitters. Here we present a model that encapsulates the essential\nphysics of coupling to phonons, which governs the behavior of real\nsingle-photon emitters, and critically evaluate several approximations that are\ncommonly utilized. Emission in the telecom wavelength range is highly\ndesirable, but our model shows that nonradiative processes are greatly enhanced\nat these low photon energies, leading to a decrease in efficiency. Our results\nsuggest that reducing the phonon frequency is a fruitful avenue to enhance the\nefficiency."
    },
    {
        "anchor": "Perturbo: a software package for ab initio electron-phonon interactions,\n  charge transport and ultrafast dynamics: Perturbo is a software package for first-principles calculations of charge\ntransport and ultrafast carrier dynamics in materials. The current version\nfocuses on electron-phonon interactions and can compute phonon-limited\ntransport properties such as the conductivity, carrier mobility and Seebeck\ncoefficient. It can also simulate the ultrafast nonequilibrium electron\ndynamics in the presence of electron-phonon scattering. Perturbo uses results\nfrom density functional theory and density functional perturbation theory\ncalculations as input, and employs Wannier interpolation to reduce the\ncomputational cost. It supports norm-conserving and ultrasoft pseudopotentials,\nspin-orbit coupling, and polar electron-phonon corrections for bulk and 2D\nmaterials. Hybrid MPI plus OpenMP parallelization is implemented to enable\nefficient calculations on large systems (up to at least 50 atoms) using\nhigh-performance computing. Taken together, Perturbo provides efficient and\nbroadly applicable ab initio tools to investigate electron-phonon interactions\nand carrier dynamics quantitatively in metals, semiconductors, insulators, and\n2D materials.",
        "positive": "In-situ study and modeling of the reaction kinetics during molecular\n  beam epitaxy of GeO2 and its etching by Ge: Rutile GeO2 has been predicted to be an ultra-wide bandgap semiconductor\nsuitable for future power electronics devices while quartz-like GeO2 shows\npiezoelectric properties. To explore these crystalline phases for application\nand fundamental materials investigations, molecular beam epitaxy (MBE) is a\nwell-suited thin film growth technique. In this study, we investigate the\nreaction kinetics of GeO2 during plasma-assisted MBE using elemental Ge and\nplasma-activated oxygen fluxes. The growth rate as a function of oxygen flux is\nmeasured in-situ by laser reflectometry at different growth temperatures. A\nflux of the suboxide GeO desorbing off the growth surface is identified and\nquantified in-situ by the line-of-sight quadrupole mass spectrometry. Our\nmeasurements reveal that the suboxide formation and desorption limits the\ngrowth rate under metal-rich or high temperature growth conditions, and leads\nto etching of the grown GeO2 layer under Ge flux in the absence of oxygen. The\nquantitative results fit the sub-compound mediated reaction model, indicating\nthe intermediate formation of the suboxide at the growth front. This model is\nfurther utilized to delineate the GeO2-growth window in terms of oxygen-flux\nand substrate temperature. Our study can serve as a guidance for the thin film\nsynthesis of GeO2 and defect-free mesa etching in future GeO2-device\nprocessing."
    },
    {
        "anchor": "A Simple Model for Anisotropic Step Growth: We consider a simple model for the growth of isolated steps on a vicinal\ncrystal surface. It incorporates diffusion and drift of adatoms on the terrace,\nand strong step and kink edge barriers. Using a combination of analytic methods\nand Monte Carlo simulations, we study the morphology of growing steps in\ndetail. In particular, under typical Molecular Beam Epitaxy conditions the step\nmorphology is linearly unstable in the model and develops fingers separated by\ndeep cracks. The vertical roughness of the step grows linearly in time, while\nhorizontally the fingers coarsen proportional to $t^{0.33}$. We develop scaling\narguments to study the saturation of the ledge morphology for a finite width\nand length of the terrace.",
        "positive": "Growth of rare-earth monopnictide DySb single crystal by novel Self-flux\n  method: This report presents a new synthesis protocol for the single crystal growth\nof rare earth monopnictide DySb by self-flux technique. A detailed structural,\ntransport and magnetic characterization have been done using X-Ray diffraction\n(XRD), High resolution X-Ray diffraction (HRXRD), resistivity and magnetization\nmeasurements respectively. The Rietveld refinement of powder XRD pattern\nconfirms that the grown crystal is in single phase and crystallizes in space\ngroup Fm3m(225) of rock-salt type crystal structure. HRXRD on cleaved crystal\nconfirms the single crystalline nature while rocking curve analysis reveals the\nhigh quality of the grown crystal. Temperature dependent resistivity and\nmagnetization measurements show a transition at 9.7K from paramagnetic (PM) to\nantiferromagnetic (AFM) state."
    },
    {
        "anchor": "Observation of room-temperature ferroelectricity in elemental Te\n  nanowires: Ferroelectrics are essential in low-dimensional memory devices for multi-bit\nstorage and high-density integration. A polar structure is a necessary premise\nfor ferroelectricity, mainly existing in compounds. However, it is usually rare\nin elemental materials, causing a lack of spontaneous electric polarization.\nHere, we report an unexpected room-temperature ferroelectricity in few-chain Te\nnanowires. Out-of-plane ferroelectric loops and domain reversal are observed by\npiezoresponse force microscopy. Through density functional theory, we attribute\nthe ferroelectricity to the ion-displacement created by the interlayer\ninteraction between lone pair electrons. Ferroelectric polarization can induce\na strong field effect on the transport along the Te chain, supporting a\nself-gated field-effect transistor. It enables a nonvolatile memory with high\nin-plane mobility, zero supply voltage, multilevel resistive states, and a high\non/off ratio. Our work provides new opportunities for elemental ferroelectrics\nwith polar structures and paves a way towards applications such as low-power\ndissipation electronics and computing-in-memory devices.",
        "positive": "Frustration Effects in Antiferromagnetic FCC Heisenberg Films: We study the effects of frustration in an antiferromagnetic film of FCC\nlattice with Heisenberg spin model including an Ising-like anisotropy. Monte\nCarlo (MC) simulations have been used to study thermodynamic properties of the\nfilm. We show that the presence of the surface reduces the ground state (GS)\ndegeneracy found in the bulk. The GS is shown to depend on the surface in-plane\ninteraction $J_s$ with a critical value at which ordering of type I coexists\nwith ordering of type II. Near this value a reentrant phase is found. Various\nphysical quantities such as layer magnetizations and layer susceptibilities are\nshown and discussed. The nature of the phase transition is also studied by\nhistogram technique. We have also used the Green's function (GF) method for the\nquantum counterpart model. The results at low-$T$ show interesting effects of\nquantum fluctuations. Results obtained by the GF method at high $T$ are\ncompared to those of MC simulations. A good agreement is observed."
    },
    {
        "anchor": "Ultrahigh ion diffusion in oxide crystal by engineering the interfacial\n  transporter channels: The mass storage and removal in solid conductors always played vital role on\nthe technological applications such as modern batteries, permeation membranes\nand neuronal computations, which were seriously lying on the ion diffusion and\nkinetics in bulk lattice. However, the ions transport was kinetically limited\nby the low diffusional process, which made it a challenge to fabricate\napplicable conductors with high electronic and ionic conductivities at room\ntemperature. It was known that at essentially all interfaces, the existed space\ncharge layers could modify the charge transport, storage and transfer\nproperties. Thus, in the current study, we proposed an acid solution/WO3/ITO\nstructure and achieved an ultrafast hydrogen transport in WO3 layer by\ninterfacial job-sharing diffusion. In this sandwich structure, the transport\npathways of the protons and electrons were spatially separated in acid solution\nand ITO layer respectively, resulting the pronounced increasing of effective\nhydrogen diffusion coefficient (Deff) up to 106 times. The experiment and\ntheory simulations also revealed that this accelerated hydrogen transport based\non the interfacial job-sharing diffusion was universal and could be extended to\nother ions and oxide materials as well, which would potentially stimulate\nsystematic studies on ultrafast mixed conductors or faster solid-state\nelectrochemical switching devices in the future.",
        "positive": "Ceramic processing and multiferroic properties of the perovskite\n  YMnO$_3$-BiFeO$_3$ binary system: The perovskite (1-x)YMnO$_3$-xBiFeO$_3$ binary system is very promising\nbecause of its multiferroic end members. Nanocrystalline phases have been\nrecently obtained by mechanosynthesis across the system, and the perovskite\nstructural evolution has been described. Two continuous solid solutions with\northorhombic Pnma and rhombohedral R3c symmetries were found, which coexist\nwithin a broad compositional interval of 0.5 < x < 0.9. This might be a\npolar-nonpolar morphotropic phase boundary region, at which strong phase-change\nmagnetoelectric responses can be expected. A major issue is phase decomposition\nat moderate temperatures that highly complicates ceramic processing. This is\nrequired for carrying out a sound electrical characterization and also for\ntheir use in devices. We present here the application of Spark Plasma Sintering\nto the ceramic processing of YMnO$_3$-BiFeO$_3$ phases. This advanced\ntechnique, when combined with nanocrystalline powders, allowed densifying\nphases at reduced processing temperatures and times, so that perovskite\ndecomposition was avoided. Electrical measurements were accomplished, and the\nresponse was shown to be mostly dominated by conduction. Nonetheless, the\nintrinsic dielectric permittivity was obtained, and a distinctive enhancement\nin the phase coexistence region was revealed. Besides, Rayleigh-type behaviour\ncharacteristic of ferroelectrics was also demonstrated for all rhombohedral\nphases. Magnetic characterization was performed in this region, and\nantiferromagnetism was shown."
    },
    {
        "anchor": "Nonreciprocal magnon propagation in a noncentrosymmetric ferromagnet: Relativistic spin-orbit interaction drastically modifies electronic band and\nendows emergent functionalities. One of the example is the Rashba effect. In\nnoncentrosymmetric systems such as interface and polar materials, the\nelectronic band is spin-splitted depending on the momentum direction owing to\nthe spin-orbit interaction, which is useful for the electric manipulation of\nspin current. Similar relativistic band-modification is also emergent for spin\nwave (magnon) in magnetic materials. The asymmetric magnon band dispersion\ninduced by the Dzyaloshinskii-Moriya interaction, which is antisymmetric\nexchange interaction originating from the spin-orbit interaction, is\ntheoretically expected, and experimentally observed recently in\nnoncentrosymmetric ferromagnets. Here, we demonstrate that the nonreciprocal\nmicrowave response can be induced by the asymmetric magnon band in a\nnoncentrosymmetric ferrimagnet LiFe$_5$O$_8$. This result may pave a new path\nto designing magnonic device based on the relativistic band engineering.",
        "positive": "Titanic Magnetoresistance in WTe2: Magnetoresistance is the change of a material's electrical resistance in\nresponse to an applied magnetic field. In addition to its intrinsic scientific\ninterest, it is a technologically important property, placing it in \"Pasteur's\nquadrant\" of research value: materials with large magnetorsistance have found\nuse as magnetic sensors 1, in magnetic memory 2, hard drives 3, transistors 4,\nand are the subject of frequent study in the field of spintronics 5, 6. Here we\nreport the observation of an extremely large one-dimensional positive\nmagnetoresistance (XMR) in the layered transition metal dichalcogenide (TMD)\nWTe2; 452,700 percent at 4.5 Kelvin in a magnetic field of 14.7 Tesla, and 2.5\nmillion percent at 0.4 Kelvin in 45 Tesla, with no saturation. The XMR is\nhighly anisotropic, maximized in the crystallographic direction where small\npockets of holes and electrons are found in the electronic structure. The\ndetermination of the origin of this effect and the fabrication of\nnanostructures and devices based on the XMR of WTe2 will represent a\nsignificant new direction in the study and uses of magnetoresistivity.\n  *The published version of the paper includes co-authors Tian Liang and Max\nHirschberger.\n  **This paper has been published with new MR data to 60T where the MR of WTe2\nreaches 13 million percent (at 0.5K) and still shows no signs of saturation. We\nalso have new electron diffraction patterns to lower temperature (10K). We\ndiscuss the possible origin of the MR as coming from an electron-hole\n'resonance' condition established by a perfect n/p ratio of 1 (more details in\na new \"extended data\" section). This makes WTe2, possibly, the first\nrealization of a perfectly balanced semimetal.\n  ***The paper is published as \"Large non-saturating magnetoresistance in WTe2\"\nin Nature (2014), DOI:10.1038/nature13763"
    },
    {
        "anchor": "Manganese Dioxide Decoration of Macroscopic Carbon Nanotube Fibers: From\n  High-Performance Liquid-Based to All-Solid-State Supercapacitors: Supercapacitors capable of providing high voltage, energy and power density\nbut yet light, low volume occupying, flexible and mechanically robust are\nhighly interesting and demanded for portable applications. Herein, freestanding\nflexible hybrid electrodes based on MnO2 nanoparticles grown on macroscopic\ncarbon nanotube fibers (CNTf-MnO2) were fabricated, without the need of any\nmetallic current collector. The CNTf, a support with excellent electrical\nconductivity, mechanical stability, and appropriate pore structure, was\nhomogeneously decorated with porous akhtenskite \\epsilon-MnO2 nanoparticles\nproduced via electrodeposition in an optimized organic-aqueous mixture.\nElectrochemical properties of these decorated fibers were evaluated in\ndifferent electrolytes including a neutral aqueous solution and a pure\n1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquid\n(PYR14TFSI). This comparison helps discriminate the various contributions to\nthe total capacitance: (surface) Faradaic and non-Faradaic processes, improved\nwetting by aqueous electrolytes. Accordingly, symmetric supercapacitors with\nPYR14TFSI led to a high specific energy of 36 Whkg_(MnO_2)^(-1) (16 Whkg-1\nincluding the weight of CNTf) and real specific power of 17 kWkg_(MnO_2)^(-1)\n(7.5 kWkg-1) at 3.0 V with excellent cycling stability. Moreover, flexible all\nsolid-state supercapacitors were fabricated using PYR14TFSI-based polymer\nelectrolyte, exhibiting maximum energy density of 21 Whkg-1 and maximum power\ndensity of 8 kWkg-1 normalized by total active material.",
        "positive": "Theory and experiments on the ice-water front propagation in droplets\n  freezing on a subzero surface: An approximate theory is presented describing the propagation of the\nice-water front that develops in droplets of water that are deposited on a\nplanar surface at a temperature below the melting point of ice. A calculation\nbased on this theory is compared with our experimental observations of the time\nevolution of this front. The results of calculations of this front by Schultz\net al7, obtained by integrating numerically the exact differential equations\nfor this problem, were published graphically, but only for the time-dependent\nvelocity of this front. Unfortunately, these theoretical results cannot be\ncompared directly with our experimental observations. Our experiments were\nperformed by freezing water droplets directly on a block of dry ice, and in\norder to examine the effects of the heat conductivity of a substrate during the\nfreezing process, such droplets were also deposited on a glass plate and on a\ncopper plate placed on dry ice. The temperature at the base of these droplets,\nand the dependence of the freezing time on their size was also investigated ex\nperimentally, and compared with our analytic approximation of the theory. Such\nexperiment have not been published previously, and reveal that the usual\nassumption that the temperature at the base of the droplets is a constant, made\nin all previous theoretical papers on this subject, cannot be implemented in\npractice."
    },
    {
        "anchor": "Crack-free caustic magnesia-bonded refractory castables: A growing interest in designing high-alumina MgO-bonded refractory castables\nhas been identified in recent years due to the magnesia ability to react: (i)\nwith water at the initial processing stages of these materials (inducing the\nprecipitation of brucite phase) or (ii) with alumina, giving rise to in situ\nMgAl2O4 generation at high temperatures. Nevertheless, despite the great\npotential of caustic magnesia to be used as a binder in such systems due to its\nhigh reactivity, it is still a challenge to control the hydration reaction rate\nof this oxide and the negative effects derived from the expansive feature of\nMg(OH)2 formation. Thus, this work evaluated the incorporation of different\ncontents of aluminum hydroxyl lactate (AHL) into caustic magnesia-bonded\ncastables, aiming to control the brucite precipitation during the curing and\ndrying steps of the prepared samples, resulting in crack-free refractories. The\ndesigned compositions were characterized via flowability, setting behavior,\nX-ray diffraction, cold flexural strength, porosity, permeability and\nthermogravimetric measurements. According to the results, instead of Mg(OH)2,\nhydrotalcite-like phases [Mg6Al2(OH)16(OH)2.4.5H2O and Mg6Al2(OH)16(CO3).4H2O]\nwere the main hydrated phases identified in the AHL-containing compositions.\nThe addition of 1.0 wt.% of aluminum hydroxyl lactate to the designed castable\nproved to be, so far, the best option for this magnesia source, resulting in\nthe development of a crack-free refractory with enhanced properties and greater\nspalling resistance under heating.",
        "positive": "Tuning the Hysteresis of a Metal-Insulator Transition via Lattice\n  Compatibility: Structural phase transitions serve as the basis for many functional\napplications including shape memory alloys (SMAs), switches based on\nmetal-insulator transitions (MITs), etc. In such materials, lattice\nincompatibility between phases often results in a thermal hysteresis, which is\nintimately tied to degradation of reversibility of the transformation. The\nnon-linear theory of martensite suggests that the hysteresis of a martensitic\nphase transformation is solely determined by the lattice constants, and the\nconditions proposed for geometrical compatibility have been successfully\napplied to minimizing the hysteresis in SMAs. In this work, we apply the\nnon-linear theory to a strongly correlated oxide system (W doped VO2), and show\nthat the hysteresis of the MIT in the system can be directly tuned by adjusting\nthe lattice constants of the phases. The results underscore the profound\ninfluence structural compatibility has on intrinsic electronic properties, and\nindicate that the theory provides a universal guidance for optimizing phase\ntransforming materials."
    },
    {
        "anchor": "Electronic structure and magnetism for FeSi$_{(1-x)}$Ge$_x$ from\n  supercell calculations: Recent studies of FeSi$_{(1-x)}$Ge$_x$, which found a transition from an\ninsulating to a magnetic metallic state near $x$=0.25, have revived the\ndiscussion about the role of strong correlation in these systems. Here are spin\npolarized band calculations made for 64-atom supercells of FeSi$_{(1-x)}$Ge$_x$\nfor different $x$ and different volumes for large $x$. The results show that\nthe small band gap in FeSi is closed for $x \\geq 0.3$, because of both\nsubstitutional disorder and increased volume. Ferromagnetism appears near this\ncomposition and becomes enforced for increasing $x$. The $x$-dependence of the\nelectronic specific heat can be understood from the exchange splitting of the\ndensity-of-states near the gap. Strong volume dependencies for the properties\nof FeGe suggest experiments using pressure instead of $x$ for investigations of\nthe gap.",
        "positive": "Stacked topological insulator built from bismuth-based graphene sheet\n  analogues: Commonly materials are classified as either electrical conductors or\ninsulators. The theoretical discovery of topological insulators (TIs) in 2005\nhas fundamentally challenged this dichotomy. In a TI, spin-orbit interaction\ngenerates a non-trivial topology of the electronic band-structure dictating\nthat its bulk is perfectly insulating, while its surface is fully conducting.\nThe first TI candidate material put forward -graphene- is of limited practical\nuse since its weak spin-orbit interactions produce a band-gap of ~0.01K. Recent\nreinvestigation of Bi2Se3 and Bi2Te3, however, have firmly categorized these\nmaterials as strong three-dimensional TI's. We have synthesized the first bulk\nmaterial belonging to an entirely different, weak, topological class, built\nfrom stacks of two-dimensional TI's: Bi14Rh3I9. Its Bi-Rh sheets are graphene\nanalogs, but with a honeycomb net composed of RhBi8-cubes rather than carbon\natoms. The strong bismuth-related spin-orbit interaction renders each\ngraphene-like layer a TI with a 2400K band-gap."
    },
    {
        "anchor": "Universal stability of two-dimensional traditional semiconductors: Interest in two dimensional materials has exploded in recent years. Not only\nare they studied due to their novel electronic properties, such as the emergent\nDirac Fermion in graphene, but also as a new paradigm in which stacking layers\nof distinct two dimensional materials may enable different functionality or\ndevices. Here, through first-principles theory, we reveal a large new class of\ntwo dimensional materials which are derived from traditional III-V, II-VI, and\nI-VII semiconductors. It is found that in the ultra-thin limit all of the\ntraditional binary semi-conductors studied (a series of 26 semiconductors)\nstabilize in a two dimensional double layer honeycomb (DLHC) structure, as\nopposed to the wurtzite or zinc-blende structures associated with three\ndimensional bulk. Not only does this greatly increase the landscape of\ntwo-dimensional materials, but it is shown that in the double layer honeycomb\nform, even ordinary semiconductors, such as GaAs, can exhibit exotic\ntopological properties.",
        "positive": "Collective dynamics of domain walls: an antiferromagnetic spin texture\n  in an optical cavity: Spin canting and complex spin textures in antiferromagnetic materials can\noften be described in terms of Dzyaloshinskii-Moriya interactions (DMI). Values\nfor DMI parameters are not easily measurable directly, and often inferred from\nother quantities. In this work, we examine how domain wall dynamics in an\nantiferromagnetic optomagnonic system can display unique features directly\nrelated to the existence of DMI. Our results indicate that the presence of DMI\nenables spin interactions with cavity photons in a geometry which otherwise\nallows no magneto-optical coupling, and on the other hand modulates frequencies\nin a geometry where coupling is already realized in the absence of DMI. This\nresult may be used to measure the DMI constant in optomagnonic experiments by\ncomparing resonances obtained with different polarisations of the exciting\nfield."
    },
    {
        "anchor": "Review on Giant Magnetoelectric effects in Oxide\n  ferromagnetic/ferroelectric Layered Structures: The synthesis of layered ferrite-lead titanate zirconate (PZT) and lanthanum\nnanganite-PZT and the observation of giant magneto-electric interactions are\ndiscussed. The ferrites used in our studies included pure and Zn substituted\ncobalt-, nickel- and lithium ferrites. Ferromagnetic manganites used included\nboth calcium and strontium substituted systems. The samples were prepared from\n10-40 mm thick films obtained by tape-casting. Our studies showed strong ME\ncoupling in manganite-PZT and cobalt zinc ferrite-PZT, and a giant ME effect in\nnickel zinc ferrite-PZT. We found evidence for Zn assisted enhancement in ME\ncoefficients that were attributed to low anisotropy and high permeability that\nresulted in favorable magneto-mechanical coupling in the composites.",
        "positive": "Design Strength-Ductility Synergy of Metastable High-Entropy Alloys by\n  Tailoring Unstable Fault Energies: Metastable alloys with transformation/twinning-induced plasticity (TRIP/TWIP)\ncan overcome the strength-ductility trade-off in structural materials.\nOriginated from the development of traditional alloys, the intrinsic stacking\nfault energy (ISFE) has been relied to tailor TRIP/TWIP in high-entropy alloys\n(HEA), but with limited quantitative success. Herein, we demonstrate a new\nstrategy for designing metastable HEAs and validate its effectiveness by\ndiscovering seven new alloys with experimentally observed metastability for\nTRIP/TWIP. We propose unstable fault energies as the more effective design\nmetric and attribute the deformation mechanism of metastable face-centered\ncubic alloys to UMFE (unstable martensite fault energy)/UTFE (unstable twin\nfault energy) rather than ISFE. Among the studied HEAs and steels, the\ntraditional ISFE criterion fails in more than half of the cases, while the\nUMFE/UTFE criterion accurately predicts the deformation mechanisms in all\ncases. The UMFE/UTFE criterion provides a new paradigm for developing\nmetastable alloys with TRIP/TWIP for enhanced strength-ductility synergy."
    },
    {
        "anchor": "Exploring interlayer Dirac cone coupling in commensurately rotated\n  few-layer graphene on SiC(000-1): We investigate electronic band-structure images in reciprocal space of few\nlayer graphene epitaxially grown on SiC(000-1). In addition to the observation\nof commensurate rotation angles of the graphene layers, the k-space images\nrecorded near the Fermi edge highlight structures originating from diffraction\nof the Dirac cones due to the relative rotation of adjacent layers. The\n21.9{\\deg} and 27{\\deg} rotation angles between two sheets of graphene are\nresponsible for a periodic pattern that can be described with a superlattice\nunit cells. The superlattice generates replicas of Dirac cones with smaller\nwave vectors, due to a Brillouin zone folding.",
        "positive": "Unraveling the origin of antiferromagnetic coupling at YIG/permalloy\n  interface: We investigate the structural and electronic origin of antiferromagnetic\ncoupling in the Yttrium iron garnet (YIG) and permalloy (Py) bilayer system at\nthe atomic level. Ferromagnetic Resonance (FMR) reveal unique hybrid modes in\nsamples prepared with surface ion milling, indicative of antiferromagnetic\nexchange coupling at the YIG/Py interface. Using scanning transmission electron\nmicroscopy (STEM), we highlight significant interfacial differences introduced\nby ion-milling. The observations suggests that the antiferromagnetic coupling\nin YIG/Py bilayers is predominantly driven by an oxygen-mediated super-exchange\ncoupling mechanism on the tetrahedral Fe terminated YIG surface, which is\nsupported by density functional theory (DFT) calculations. This research\nprovides critical insight into the fundamental mechanisms governing the\nefficiency of coupling in magnetic bilayers and underscores the pivotal role of\noxide surface termination in modulating magnetic interfacial dynamics."
    },
    {
        "anchor": "Displacement Field and Elastic Energy of a Circular Twist Disclination\n  for Large Deformations - an Example how to Treat Nonlinear Boundary Value\n  Problems with Computer Algebra Systems: A circular twist disclination is a nontrivial example of a defect in an\nelastic continuum that causes large deformations. The minimal potential energy\nand the corresponding displacement field is calculated by solving the\nEuler-Lagrange-equations. The nonlinear incompressibility constraint is\nrigorously taken into account. By using an appropriate curvilinear coordinate\nsystem a finer resolution in the regions of large deformations is obtained and\nthe dimension of the arising nonlinear PDE's is reduced to two. The extensive\nalgebraic calculations that arise are done by a computer algebra system (CAS).\nThe PDE's are then solved by a difference scheme using the Newton-Raphson\nalgorithm of successive approximations for multidimensional equations.\nAdditional features for global convergence are implemented. To obtain basic\nstates that are sufficiently close to the solution, a one dimensional\nlinearized version of the equation is solved with a numerical computation that\nreproduces the analytical results of Huang and Mura (1970). With this method,\nrigorous solutions of the nonlinear equations without any additional\nsimplifications can be obtained. The numerical results show a contraction of\nthe singularity line which corresponds to the well-known Poynting effect in\nnonlinear elasticity. This combination of analytical and numerical computations\nproves to be a versatile method to solve nonlinear boundary value problems in\ncomplicated geometries.",
        "positive": "Origin and evolution of surface spin current in topological insulators: The Dirac surface states of topological insulators offer a unique possibility\nfor creating spin polarized charge currents due to the spin-momentum locking.\nHere we demonstrate that the control over the bulk and surface contribution is\ncrucial to maximize the charge-to-spin conversion efficiency. We observe an\nenhancement of the spin signal due to surface-dominated spin polarization while\nfreezing out the bulk conductivity in semiconducting Bi1.5Sb0.5Te1.7Se1.3 below\n100K. Detailed measurements up to room temperature exhibit a strong reduction\nof the magnetoresistance signal between 2 and 100K, which we attribute to the\nthermal excitation of bulk carriers and to the electron-phonon coupling in the\nsurface states. The presence and dominance of this effect up to room\ntemperature is promising for spintronic science and technology."
    },
    {
        "anchor": "Influence of microstructure on the application of Ni-Mn-In Heusler\n  compounds for multicaloric cooling using magnetic field and uniaxial stress: Novel multicaloric cooling utilizing the giant caloric response of\nNi-Mn-based metamagnetic shape-memory alloys to different external stimuli such\nas magnetic field, uniaxial stress and hydrostatic pressure is a promising\ncandidate for energy-efficient and environmentally-friendly refrigeration.\nHowever, the role of microstructure when several external fields are applied\nsimultaneously or sequentially has been scarcely discussed in literature. Here,\nwe synthesized ternary Ni-Mn-In alloys by suction casting and arc melting and\nanalyzed the microstructural influence on the response to magnetic fields and\nuniaxial stress. By combining SEM-EBSD and stress-strain data, a significant\neffect of texture on the stress-induced martensitic transformation is revealed.\nIt is shown that a <001> texture can strongly reduce the critical\ntransformation stresses. The effect of grain size on the material failure is\ndemonstrated and its influence on the magnetic-field-induced transformation\ndynamics is investigated. Temperature-stress and temperature-magnetic field\nphase diagrams are established and single caloric performances are\ncharacterized in terms of ${\\Delta}{s_T}$ and ${\\Delta}{T_{ad}}$. The cyclic\n${\\Delta}{T_{ad}}$ values are compared to the ones achieved in the multicaloric\nexploiting-hysteresis cycle. It turns out that a suction-cast microstructure\nand the combination of both stimuli enables outstanding caloric effects in\nmoderate external fields which can significantly exceed the single caloric\nperformances. In particular for Ni-Mn-In, the maximum cyclic effect in magnetic\nfields of 1.9 T is increased by more than 200 % to -4.1 K when a moderate\nsequential stress of 55 MPa is applied. Our results illustrate the crucial role\nof microstructure for multicaloric cooling using Ni-Mn-based metamagnetic\nshape-memory alloys.",
        "positive": "Probing the Intrinsic Properties of Exfoliated Graphene: Raman\n  Spectroscopy of Free-Standing Monolayers: The properties of pristine, free-standing graphene monolayers prepared by\nmechanical exfoliation of graphite are investigated. The graphene monolayers,\nsuspended over open trenches, are examined by means of spatially resolved Raman\nspectroscopy of the G-, D-, and 2D-phonon modes. The G-mode phonons exhibit\nreduced energies (1580 cm-1) and increased widths (14 cm-1) compared to the\nresponse of graphene monolayers supported on the SiO2 covered substrate. From\nanalysis of the G-mode Raman spectra, we deduce that the free-standing graphene\nmonolayers are essentially undoped, with an upper bound of 2x10^11 cm-2 for the\nresidual carrier concentration. On the supported regions, significantly higher\nand spatially inhomogeneous doping is observed. The free-standing graphene\nmonolayers show little local disorder, based on the very weak Raman D-mode\nresponse. The two-phonon 2D mode of the free-standing graphene monolayers is\ndownshifted in frequency compared to that of the supported region of the\nsamples and exhibits a narrowed, positively skewed line shape."
    },
    {
        "anchor": "Giant magnetoresistance, three-dimensional Fermi surface and origin of\n  resistivity plateau in YSb semimetal: Very strong magnetoresistance and a resistivity plateau impeding low\ntemperature divergence due to insulating bulk are hallmarks of topological\ninsulators and are also present in topological semimetals where the plateau is\ninduced by magnetic field, when time-reversal symmetry (protecting surface\nstates in topological insulators) is broken. Similar features were observed in\na simple rock-salt-structure LaSb, leading to a suggestion of the possible\nnon-trivial topology of 2D states in this compound. We show that its sister\ncompound YSb is also characterized by giant magnetoresistance exceeding one\nthousand percent and low-temperature plateau of resistivity. We thus performed\nin-depth analysis of YSb Fermi surface by band calculations, magnetoresistance,\nand Shubnikov--de Haas effect measurements, which reveals only\nthree-dimensional Fermi sheets. Kohler scaling applied to magnetoresistance\ndata accounts very well for its low-temperature upturn behavior. The\nfield-angle-dependent magnetoresistance demonstrates a 3D-scaling yielding\neffective mass anisotropy perfectly agreeing with electronic structure and\nquantum oscillations analysis, thus providing further support for 3D-Fermi\nsurface scenario of magnetotransport, without necessity of invoking\ntopologically non-trivial 2D states. We discuss data implying that analogous\nfield-induced properties of LaSb can also be well understood in the framework\nof 3D multiband model.",
        "positive": "Real space finite difference method for conductance calculations: We present a general method for calculating coherent electronic transport in\nquantum wires and tunnel junctions. It is based upon a real space high order\nfinite difference representation of the single particle Hamiltonian and wave\nfunctions. Landauer's formula is used to express the conductance as a\nscattering problem. Dividing space into a scattering region and left and right\nideal electrode regions, this problem is solved by wave function matching (WFM)\nin the boundary zones connecting these regions. The method is tested on a model\ntunnel junction and applied to sodium atomic wires. In particular, we show that\nusing a high order finite difference approximation of the kinetic energy\noperator leads to a high accuracy at moderate computational costs."
    },
    {
        "anchor": "Handling magnetic anisotropy and dynamic magnetic response of\n  ferromagnetic multilayers in flexible substrates: We investigate the dynamic magnetic response of ferromagnetic flexible\nNiFe/Ta and FeCuNbSiB/Ta multilayers under external stress. We explore the\npossibility of handling magnetic anisotropy and dynamic magnetic response of\nflexible magnetostrictive nanostructures. We quantify the sensitivity of the\nmultilayers under external stress by calculating the ratio $|\\Delta\n\\textrm{MI}|/|\\Delta \\bar{\\sigma}|$ and show that considerable values can be\nreached by tuning the magnetic field, frequency, magnetostriction constant, and\nexternal stress. The results reveal possibilities of application of flexible\nmagnetostrictive multilayers under external stress and place them as very\nattractive candidates as element sensor for the development of sensitive smart\ntouch sensors.",
        "positive": "Ab initio electronic density in solids by many-body plane-wave\n  auxiliary-field quantum Monte Carlo calculations: We present accurate many-body results of the electronic densities in several\nsolid materials, including Si, NaCl, and Cu. These results are obtained using\nthe ab initio auxiliary-field quantum Monte Carlo (AFQMC) method working in a\nplane-wave basis with norm-conserving, multiple-projector pseudopotentials.\nAFQMC has been shown to be an excellent many-body total energy method.\nComputation of observables and correlation functions other than the\nground-state energy requires back-propagation, whose adaption and\nimplementation in the plane-wave basis AFQMC framework are discussed in the\npresent paper. This development allows us to compute correlation functions,\nelectronic densities and interatomic forces, paving the way for geometry\noptimizations and calculations of thermodynamic properties in solids. Finite\nsupercell size effects are considerably more subtle in the many-body framework\nthan in independent-electron calculations. We analyze the convergence of the\nelectronic density, and obtain best estimates for the thermodynamic limit. The\ndensities from several typical density functionals are benchmarked against our\nnear-exact results. The electronic densities we have obtained can also be used\nto help construct improved density functionals."
    },
    {
        "anchor": "Thermoelectric effects in selfsimilar multibarrier structure based on\n  monolayer graphene: Thermoelectric effects have attracted wide attention in recent years from\nphysicists and engineers. In this work, we explore the selfsimilar patterns in\nthe thermoelectric effects of monolayer graphene based structures, by using the\nquantum relativistic Dirac equation. The transfer matrix method has been used\nto calculate the transmission coefficient. The Landauer Buttiker formalism and\nthe Cutler Mott formula were used to calculate the conductance, the Seebeck\ncoefficient, and the power factor. We find selfsimilar behavior and the scale\nfactors between generations in the transport and thermoelectric properties.\nFurthermore, we implement these scale invariances as general scaling rules. We\npresent a new analytical demonstration of selfsimilarity in the Seebeck\ncoefficient. These findings can open outstanding perspectives for\nexperimentalists to develop thermoelectric devices.",
        "positive": "Magnetocaloric particles of the Laves phase compound HoAl2 prepared by\n  electrode induction melting gas atomization: Processing magnetocaloric materials into magnetic refrigerant particles is an\nessential issue in developing high-performance magnetic refrigerators. Here, we\nsucceed in stably producing magnetocaloric particles of the promising material\nHoAl2 by a newly devised method based on electrode induction melting gas\natomization process. The particle size range is on the order of submillimeter,\nwhich is suitable for practical refrigeration systems. The resulting particles\nwith less contamination have good morphological, magnetic, and magnetocaloric\nproperties: (i) almost spherical shapes with few internal pores, (ii) a sharp\nferromagnetic transition around 30 K, and (iii) a large magnetocaloric effect\ncomparable to the bulk counterpart. These features suggest the HoAl$_{2}$\ngas-atomized particles have the potential of use as a magnetic refrigerant. The\npresented method can be applied not only to HoAl2 but also to other brittle\nmagnetocaloric materials with high melting points, facilitating the production\nof various magnetic refrigerants needed to develop magnetic refrigerators for\nhydrogen liquefaction."
    },
    {
        "anchor": "Impact of point defects on the electronic structure of paramagnetic CrN: This paper presents first principles calculations of paramagnetic cubic\nCrN$_x$ with the aim to provide deeper insight into recently published\ntransmission electron microscopy-based study on this material. Among several\ntypes of point defects which may result in N-deficient material, N vacancy is\nfound to be energetically preferred to Cr interstitial and anti-sites. Electron\nEnergy Loss Near Edge Structure of N K-edge transition is calculated for\nvarious concentrations of N vacancies in CrN$_x$, yielding the same trends as\nexperimentally observed. Analysis of the electronic structure reveals decreased\ncharge transfer from Cr sites with increased N vacancy content, hence\nincreasing the metallic character of the defected material. Finally, the\nelectronic structure is found to be strongly dependent on the local environment\n(i.e. presence of the N vacancies).",
        "positive": "Combined experimental and theoretical investigation of the\n  premartensitic transition in Ni$_2$MnGa: Ultraviolet-photoemission (UPS) measurements and supporting specific-heat,\nthermal-expansion, resistivity and magnetic-moment measurements are reported\nfor the magnetic shape-memory alloy Ni$_2$MnGa over the temperature range $100K\n< T < 250K$. All measurements detect clear signatures of the premartensitic\ntransition ($T_\\mathrm{PM}\\sim 247K$) and the martensitic transition\n($T_\\mathrm{M} \\sim 196K$). Temperature-dependent UPS shows a dramatic\ndepletion of states (pseudogap) at $T_\\mathrm{PM}$ located 0.3eV below the\nFermi energy. First-principles electronic structure calculations show that the\npeak observed at 0.3eV in the UPS spectra for $T > T_\\mathrm{PM}$ is due to the\nNi-d minority-spin electrons. Below $T_\\mathrm{M}$ this peak disappears,\nresulting in an enhanced density of states at energies around 0.8eV. This\nenhancement reflects Ni-d and Mn-d electronic contributions to the\nmajority-spin density of states and is accompanied by significant\nreconstruction of the Fermi surface."
    },
    {
        "anchor": "Spin-orbit interaction driven collective electron-hole excitations in a\n  noncentrosymmetric nodal loop Weyl semimetal: NbP is one member of a new class of nodal loop semimetals characterized by\nthe cooperative effects of spin-orbit coupling (SOC) and a lack of inversion\ncenter. Here transport and spectroscopic properties of NbP are evaluated using\ndensity functional theory methods. SOC together with the lack of inversion\nsymmetry splits degeneracies, giving rise to \"Russian doll nested\" Fermi\nsurfaces containing 4*10$^{-4}$ electron (hole) carriers/f.u. Due to the modest\nSOC strength in Nb, the Fermi surfaces map out the Weyl nodal loops. Calculated\nstructure around T$^*$~100 K in transport properties reproduces well the\nobserved transport behavior only when SOC is included, attesting to the\nprecision of the (delicate) calculations and the stoichiometry of the samples.\nLow energy collective electron-hole excitations (plasmons) in the 20-60 meV\nrange result from the nodal loop splitting.",
        "positive": "Thermopower and thermal conductivity in the Weyl semimetal NbP: The Weyl semimetal NbP exhibits an extremely large magnetoresistance (MR) and\nan ultra-high mobility. The large MR originates from a combination of the\nnearly perfect compensation between electron- and hole-type charge carriers and\nthe high mobility, which is relevant to the topological band structure. In this\nwork we report on temperature- and field-dependent thermopower and thermal\nconductivity experiments on NbP. Additionally, we carried out complementary\nheat capacity, magnetization, and electrical resistivity measurements. We found\na giant adiabatic magnetothermopower with a maximum of 800 $\\mu$V/K at 50 K in\na field of 9 T. Such large effects have been observed rarely in bulk materials.\nWe suggest that the origin of this effect might be related to the high\ncharge-carrier mobility. We further observe pronounced quantum oscillations in\nboth thermal conductivity and thermopower. The obtained frequencies compare\nwell with our heat capacity and magnetization data."
    },
    {
        "anchor": "Strain-induced topological charge control in multifold fermion systems: Multifold fermion systems feature free fermionic excitations, which have no\ncounterparts in high-energy physics, and exhibit several unconventional\nproperties. Using first-principles calculations, we predict that strain\nengineering can be used to control the distribution of topological charges in\ntransition metal silicide candidate CoSi, hosting multifold fermions. We\ndemonstrate that breaking the rotational symmetry of the system, by choosing a\nsuitable strain, destroys the multifold fermions, and at the same time results\nin the creation of Weyl points. We introduce a low energy effective model to\ncomplement the results obtained from density functional calculations. Our\nfindings suggest that strain-engineering is a useful approach to tune\ntopological properties of multifold fermions.",
        "positive": "$\\textit{In situ}$ electric-field control of ferromagnetic resonance in\n  the low-loss organic-based ferrimagnet V[TCNE]$_{x\\sim 2}$: We demonstrate indirect electric-field control of ferromagnetic resonance\n(FMR) in devices that integrate the low-loss, molecule-based, room-temperature\nferrimagnet vanadium tetracyanoethylene (V[TCNE]$_{x \\sim 2}$) mechanically\ncoupled to PMN-PT piezoelectric transducers. Upon straining the V[TCNE]$_x$\nfilms, the FMR frequency is tuned by more than 6 times the resonant linewidth\nwith no change in Gilbert damping for samples with $\\alpha = 6.5 \\times\n10^{-5}$. We show this tuning effect is due to a strain-dependent magnetic\nanisotropy in the films and find the magnetoelastic coefficient $|\\lambda_S|\n\\sim (1 - 4.4)$ ppm, backed by theoretical predictions from DFT calculations\nand magnetoelastic theory. Noting the rapidly expanding application space for\nstrain-tuned FMR, we define a new metric for magnetostrictive materials,\n$\\textit{magnetostrictive agility}$, given by the ratio of the magnetoelastic\ncoefficient to the FMR linewidth. This agility allows for a direct comparison\nbetween magnetostrictive materials in terms of their comparative efficacy for\nmagnetoelectric applications requiring ultra-low loss magnetic resonance\nmodulated by strain. With this metric, we show V[TCNE]$_x$ is competitive with\nother magnetostrictive materials including YIG and Terfenol-D. This combination\nof ultra-narrow linewidth and magnetostriction in a system that can be directly\nintegrated into functional devices without requiring heterogeneous integration\nin a thin-film geometry promises unprecedented functionality for electric-field\ntuned microwave devices ranging from low-power, compact filters and circulators\nto emerging applications in quantum information science and technology."
    },
    {
        "anchor": "Hydrodynamic Phonon Transport Perpendicular to Diffuse-Gray Boundaries: In this paper, we examine the application of an ideal phonon-hydrodynamic\nmaterial as the heat transfer medium between two non-hydrodynamic contacts with\na finite temperature difference. We use the integral-equation approach to solve\na modified phonon Boltzmann transport equation with the displaced Bose-Einstein\ndistribution as the equilibrium distribution between two boundaries\nperpendicular to the heat transfer direction. When the distance between the\nboundaries is smaller than the phonon normal scattering mean free path, our\nsolution converges to the ballistic limit as expected. In the other limit, we\nfind that, although the local thermal conductivity in the bulk of the\nhydrodynamic material approaches infinity, the thermal boundary resistance at\nthe hydrodynamic/non-hydrodynamic interfaces becomes dominant. Our study\nprovides insights to both the steady-state thermal characterization of\nphonon-hydrodynamic materials and the practical application of\nphonon-hydrodynamic materials for thermal management.",
        "positive": "Current transport in Ni Schottky barrier on GaN epilayer grown on free\n  standing substrates: In this paper, the Ni Schottky barrier on GaN epilayer grown on free standing\nsubstrates has been characterized. First, transmission electrical microscopy\n(TEM) images and nanoscale electrical analysis by conductive atomic force\nmicroscopy (C-AFM) of the bare material allowed visualizing structural defects\nin the crystal, as well as local inhomogeneities of the current conduction. The\nforward current-voltage (I-V) characteristics of Ni/GaN vertical Schottky\ndiodes fabricated on the epilayer gave average values of the Schottky barrier\nheight of 0.79 eV and ideality factor of 1.14. A statistical analysis over a\nset of diodes, combined with temperature dependence measurements, confirmed the\nformation of an inhomogeneous Schottky barrier in this material. From a plot of\nFB versus n, an ideal homogeneous barrier close to 0.9 eV was estimated,\nsimilar to that extrapolated by capacitance-voltage (C-V) analysis. Local I-V\ncurves, acquired by means of C-AFM, displayed the inhomogeneous distribution of\nthe onset of current conduction, which in turn resembles the one observed in\nthe macroscopic Schottky diodes. Finally, the reverse characteristic of the\ndiodes fabricated in the defects-free region have been acquired at different\ntemperature and its behaviour has been described by the thermionic field\nemission (TFE) model."
    },
    {
        "anchor": "Controlling magnetisation's reversal mechanism and hyperthermia\n  efficiency in core/shell magnetic nanoparticles by tuning the interphase\n  coupling: Magnetic particle hyperthermia, in which colloidal nanostructures are exposed\nto an alternating magnetic field, is a promising approach to cancer therapy.\nUnfortunately, the clinical efficacy of hyperthermia has not yet been\noptimized. Consequently, routes to improve magnetic particle hyperthermia such\nas designing hybrid structures comprised from different phase materials are\nactively pursued. Here we demonstrate enhanced hyperthermia efficiency in\nrelative large spherical Fe/Fe-oxide core/shell nanoparticles through the\nmanipulation of interactions between the core and shell phases. Experimental\nresults on exemplary samples with diameters in the range 30-80 nm indicated a\ndirect correlation of hysteresis losses to the observed temperature elevation\nrate with a maximum efficiency of around 0.9 kW/g. The absolute particle size,\nthe core/shell ratio, and the interposition of a thin w\\\"ustite interlayer, are\nshown to have powerful effects on the specific absorption rate. By comparing\nour measurements to micromagnetic calculations we have unveiled topologically\nnon-trivial magnetisation reversal modes under which interparticle interactions\nbecome negligible, aggregates formation is minimized, and the energy that is\nconverted into heat is increased. This information has been overlooked till\ndate and is in stark contrast to the existing knowledge on homogeneous\nparticles.",
        "positive": "H-Si bonding-induced unusual electronic properties of silicene: a method\n  to identify hydrogen concentration: Hydrogenated silicenes possess peculiar properties owing to the strong H-Si\nbonds, as revealed by an investigation using first principles calculations. The\nvarious charge distributions, bond lengths, energy bands, and densities of\nstates strongly depend on different hydrogen configurations and concentrations.\nThe competition of strong H-Si bondings and weak sp3 hybridization dominate the\nelectronic properties. Chair configurations belong to semiconductors, while the\ntop configurations show a nearly dispersionless energy band at the Fermi level.\nBoth two systems display H-related partially flat bands at middle energy, and\nrecovery of low-lying \\pi bands during the reduction of concentration. Their\ndensities of states exhibit prominent peaks at middle energy, and the top\nsystems have a delta-funtion-like peak at E=0. The intensity of these peaks are\ngradually weakened as the concentration decreases, providing an effective\nmethod to identify the H-concentration in scanning tunneling spectroscopy\nexperiments."
    },
    {
        "anchor": "Thermal and Dynamic Effects in Langevin Simulation of Hysteresis in\n  Nanoscale Pillars: Dynamic quantities related to hysteresis have been measured in micromagnetic\nsimulations of single-domain nanoscale magnets at nonzero temperature. The\nhysteresis-loop area and magnetization-field correlation display the\ncharacteristics of resonance, and the resonance frequency is found to be\ntemperature dependent. The period-averaged magnetization displays symmetry\nbreaking at high frequencies.",
        "positive": "Effect of epitaxial strain on cation and anion vacancy formation in MnO: Biaxial strain in coherent epitaxial thin films can have a pronounced effect\non the point defect profile in the film material. Detailed fundamental\nknowledge of the interaction of strain with point defects is crucial in\nunderstanding the stoichiometry and resulting properties of strained thin\nfilms. Here we investigate the effect of biaxial strain on the formation energy\nof cation and anion vacancies using MnO as a model system. Our density\nfunctional theory calculations show that, as expected from local volume\narguments, compressive strain favours the formation of cation vacancies.\nInterestingly, we find that small compressive and tensile strains lead to\nordering of the resulting holes along the in-plane and normal direction\nrespectively, which should manifest in different anisotropic properties in the\ntwo strain states."
    },
    {
        "anchor": "Wave model of forming of the martensite crystal in the heterogeneity\n  medium: In the current work considering the wave model of the crystal growth control,\nan influence of heterogeneity of the medium on the forming martensite crystal s\nprofile was examined. The considering of the heterogeneity is provided with the\nhelp of putting into operations the space-depending effective attenuation of\nthe waves. The description of the heterogeneity was fulfilled in three\ndifferent ways: exponential, quadratic and inverse-quadratic. It was shown,\nthat dependently of the heterogeneity of the medium various martensite crystal\ns profile can be implemented, considering the shape of its butts as well. In\nparticular the plate-like and the wedge-like of the crystal shapes are\nfeasible.",
        "positive": "Ionization of Cucurbiturils as a Pathway to More Stable Host-Guest\n  Complexes: Cucurbiturils are particularly interesting to chemists, because these\nmacrocyclic molecules are suitable hosts for an array of neutral and cationic\nspecies. It is believed that the host-guest binding originated from hydrophobic\ninteractions and ion-dipole interactions in the case of cationic guests. The\nfact that an elementary unit of cucurbiturils consists of two fused imidazole\nrings, which ionize readily, has remained largely unnoticed up to now. This\nwork reports ionized cucurbiturils and their binding to C60 fullerene using\nversatile electronic-precision description. The methodology is based on density\nfunctional theory. We assert that cationization of cucurbiturils fosters\nC60-cucurbituril binding due to polarization of electron density in C60.\nTherefore, more stable host-guest complexes can be derived."
    },
    {
        "anchor": "Disorder is good for you: The influence of local disorder on strain\n  localization and ductility of strain softening materials: We formulate a generic concept model for the deformation of a locally\ndisordered, macroscopically homogeneous material which undergoes irreversible\nstrain softening during plastic deformation. We investigate the influence of\nthe degree of microstructural heterogeneity and disorder on the concomitant\nstrain localization process (formation of a macroscopic shear band). It is\nshown that increased microstructural heterogeneity delays strain localization\nand leads to an increase of the plastic regime in the macroscopic stress-strain\ncurves. The evolving strain localization patterns are characterized and\ncompared to models of shear band formation published in the literature.",
        "positive": "Clarification of size effects in polycrystalline BaTiO3 thin films by\n  means of the specific heat measurements: grain size or film thickness?: Specific heat of polycrystalline BaTiO3 thin films on the fused quartz\nsubstrate was measured by ac-hot probe method. Phase transition temperature,\nexcess entropy and spontaneous polarization were determined as a function of\nfilm thickness and grain size. The variation of the latter was obtained in the\nlimits 30 - 150 nm by changing of the temperature of the substrate during\nsputtering while thickness of films 20 - 1100 nm was controlled by the\nconditions of sputtering. It was found that the relation between the thickness\nand grain size is important for the size effects in polycrystalline films."
    },
    {
        "anchor": "Band gap engineering of MoS$_2$ upon compression: Molybdenum disulfide (MoS$_2$) is a promising candidate for 2D nanoelectronic\ndevices, that shows a direct band-gap for monolayer structure. In this work we\nstudy the electronic structure of MoS$_2$ upon both compressive and tensile\nstrains with first-principles density-functional calculations for different\nnumber of layers. The results show that the band-gap can be engineered for\nexperimentally attainable strains (i.e. $\\pm 0.15$). However compressive strain\ncan result in bucking that can prevent the use of large compressive strain. We\nthen studied the stability of the compression, calculating the critical strain\nthat results in the on-set of buckling for free-standing nanoribbons of\ndifferent lengths. The results demonstrate that short structures, or few-layer\nMoS$_2$, show semi-conductor to metal transition upon compressive strain\nwithout bucking.",
        "positive": "Spatiotemporal visualization of a surface acoustic wave coupled to\n  magnons across a submillimeter-long sample by pulsed laser interferometry: Surface acoustic waves (SAWs) coupled to magnons have attracted much\nattention because they allow for the long-range transport of magnetic\ninformation which cannot be achieved by magnon alone. We employed pulsed laser\ninterferometry to visualize the entire spatiotemporal dynamics of a SAW that\ntravels on a nickel (Ni) thin film and is coupled to magnons. It was possible\nto trace the coupling-induced amplitude reduction and phase shift that occurs\nas the SAW propagates over a distance of 0.4 mm. The observed changes are\nconsistent with results obtained from conventional radio-frequency transmission\nmeasurements, which probe the total SAW absorption due to magnon--phonon\ncoupling. This result verifies that our method can accurately capture the\nspatiotemporal dynamics of a SAW coupled to magnons across the entire length of\nthe sample. Additionally, we validated our time-resolved profiles by comparing\nthem with theoretical results that take the echo wave due to reflection into\naccount. The impact of the echo wave is significant even when it has propagated\nover a distance on the order of millimeters. Our imaging results highlight the\nvisualization of the long-range propagation of the SAW coupled to magnons and\noffer more information about the surface vibration profiles in such devices."
    },
    {
        "anchor": "Structural phase stability and Magnetism in Co2FeO4 spinel oxide: We report a correlation between structural phase stability and magnetic\nproperties of Co2FeO4 spinel oxide. We employed mechanical alloying and\nsubsequent annealing to obtain the desired samples. The particle size of the\nsamples changes from 25 nm to 45 nm. The structural phase separation of\nsamples, except sample annealed at 9000C, into Co rich and Fe rich spinel phase\nhas been examined from XRD spectrum, SEM picture, along with EDAX spectrum, and\nmagnetic measurements. The present study indicated the ferrimagnetic character\nof Co2FeO4, irrespective of structural phase stability. The observation of\nmixed ferrimagnetic phases, associated with two Curie temperatures at TC1 and\nTC2 (>TC1), respectively, provides the additional support of the splitting of\nsingle cubic spinel phase in Co2FeO4 spinel oxide.",
        "positive": "Crackling noise during failure of alumina under compression: effect of\n  porosity: We study the acoustic emission avalanches during the failure process of\nporous alumina samples (Al2O3) under compression. Specimens with different\nporosities ranging from 30% to 59% have been synthetized from a mixture of\nfine-grained alumina and graphite. The compressive strength as well as the\ncharacteristics of the acoustic activity have been determined. The statistical\nanalysis of the recorded acoustic emission pulses reveals, for all porosities,\na broad distribution of energies with a fat tail, compatible with the existence\nof an underlying critical point. In the region of 35%-55% porosity, the energy\ndistributions of the acoustic emission signals are compatible with a power law\nbehavior over two decades in energy with an exponent \\epsilon = 1.8+/-0.1."
    },
    {
        "anchor": "Universal electric-field-driven resistive transition in narrow-gap Mott\n  insulators: One of today's most exciting research frontier and challenge in condensed\nmatter physics is known as Mottronics, whose goal is to incorporate strong\ncorrelation effects into the realm of electronics. In fact, taming the Mott\ninsulator-to-metal transition (IMT), which is driven by strong electronic\ncorrelation effects, holds the promise of a commutation speed set by a quantum\ntransition, and with negligible power dissipation. In this context, one\npossible route to control the Mott transition is to electrostatically dope the\nsystems using strong dielectrics, in FET-like devices. Another possibility is\nthrough resistive switching, that is, to induce the insulator-to-metal\ntransition by strong electric pulsing. This action brings the correlated system\nfar from equilibrium, rendering the exact treatment of the problem a difficult\nchallenge. Here, we show that existing theoretical predictions of the\noff-equilibrium manybody problem err by orders of magnitudes, when compared to\nexperiments that we performed on three prototypical narrow gap Mott systems\nV2-xCrxO3, NiS2-xSex and GaTa4Se8, and which also demonstrate a striking\nuniversality of this Mott resistive transition (MRT). We then introduce and\nnumerically study a model based on key theoretically known physical features of\nthe Mott phenomenon in the Hubbard model. We find that our model predictions\nare in very good agreement with the observed universal MRT and with a\nnon-trivial timedelay electric pulsing experiment, which we also report. Our\nstudy demonstrates that the MRT can be associated to a dynamically directed\navalanche.",
        "positive": "Machine learning force fields: Construction, validation, and outlook: Force fields developed with machine learning methods in tandem with quantum\nmechanics are beginning to find merit, given their (i) low cost, (ii) accuracy,\nand (iii) versatility. Recently, we proposed one such approach, wherein, the\nvectorial force on an atom is computed directly from its environment. Here, we\ndiscuss the multi-step workflow required for their construction, which begins\nwith generating diverse reference atomic environments and force data, choosing\na numerical representation for the atomic environments, down selecting a\nrepresentative training set, and lastly the learning method itself, for the\ncase of Al. The constructed force field is then validated by simulating complex\nmaterials phenomena such as surface melting and stress-strain behavior - that\ntruly go beyond the realm of $ab\\ initio$ methods both in length and time\nscales. To make such force fields truly versatile an attempt to estimate the\nuncertainty in force predictions is put forth, allowing one to identify areas\nof poor performance and paving the way for their continual improvement."
    },
    {
        "anchor": "Ba8MnNb6O24: a model two-dimensional spin-5/2 triangular lattice\n  antiferromagnet: We successfully synthesized and characterized the triangular lattice\nanitferromagnet Ba$_8$MnNb$_6$O$_{24}$, which comprises equilateral spin-5/2\nMn$^{2+}$ triangular layers separated by six non-magnetic Nb$^{5+}$ layers. The\ndetailed susceptibility, specific heat, elastic and inelastic neutron\nscattering measurements, and spin wave theory simulation on this system reveal\nthat it has a 120 degree ordering ground state below T$_N$ = 1.45 K with\nin-plane nearest-neighbor exchange interaction ~0.11 meV. While the large\nseparation 18.9 A between magnetic layers makes the inter-layer exchange\ninteraction virtually zero, our results suggest that a weak easy-plane\nanisotropy is the driving force for the k$_m$ = (1/3 1/3 0) magnetic ordering.\nThe magnetic properties of Ba$_8$MnNb$_6$O$_{24}$, along with its classical\nexcitation spectra, contrast with the related triple perovskite\nBa$_3$MnNb$_2$O$_9$, which shows easy-axis anisotropy, and the iso-structural\ncompound Ba$_8$CoNb$_6$O$_{24}$, in which the effective spin-1/2 Co$^{2+}$\nspins do not order down to 60 mK and in which the spin dynamics shows sign of\nstrong quantum effects.",
        "positive": "Towards a working density-functional theory for polymers:\n  First-principles determination of the polyethylene crystal structure: Equilibrium polyethylene crystal structure, cohesive energy, and elastic\nconstants are calculated by density-functional theory applied with a recently\nproposed density functional (vdW-DF) for general geometries [Phys. Rev. Lett.\n92, 246401 (2004)] and with a pseudopotential-planewave scheme. The vdW-DF with\nits account for the long-ranged van der Waals interactions gives not only a\nstabilized crystal structure but also values of the calculated lattice\nparameters and elastic constants in quite good agreement with experimental\ndata, giving promise for successful application to a wider range of polymers."
    },
    {
        "anchor": "A thermodynamically consistent approach to describe the effect of\n  thermal vacancy on abnormal thermodynamic behaviors of pure metals:\n  application to body centered cubic W: In this paper, we developed a thermodynamically consistent approach to\naccount for the Gibbs energy of pure metallic element with thermal vacancy over\nwide temperature range. Taking body centered cubic (bcc) W for a demonstration,\nthe strong nonlinear increase for temperature dependence of heat capacities at\nhigh temperatures and a nonlinear Arrhenius plots of vacancy concentration in\nbcc W can be nicely reproduced by the obtained Gibbs energy. The successful\ndescription of thermal vacancy on abnormal thermodynamic behaviors in bcc W\nindicates that the presently proposed thermodynamically consistent approach is\na universal one, and applicable to the other metals.",
        "positive": "Energy gap closure of crystalline molecular hydrogen with pressure: We study the gap closure with pressure of crystalline molecular hydrogen. The\ngaps are obtained from grand-canonical Quantum Monte Carlo methods properly\nextended to quantum and thermal crystals, simulated by Coupled Electron Ion\nMonte Carlo. Nuclear zero point effects cause a large reduction in the gap\n($\\sim 2eV$). \\CP{Depending on the structure,} the fundamental indirect gap\ncloses \\CP{between 380GPa and} 530GPa for ideal crystals and 330-380GPa for\nquantum crystals. Beyond this pressure the system enters into a bad metal phase\nwhere the density of states at the Fermi level increases with pressure up to\n$\\sim$450\\CP{-500} GPa when the direct gap closes. Our work partially supports\nthe interpretation of recent experiments in high pressure hydrogen."
    },
    {
        "anchor": "Application of Finite Element, Phase-field, and CALPHAD-based Methods to\n  Additive Manufacturing of Ni-based Superalloys: Numerical simulations are used in this work to investigate aspects of\nmicrostructure and microsegregation during rapid solidification of a Ni-based\nsuperalloy in a laser powder bed fusion additive manufacturing process. Thermal\nmodeling by finite element analysis simulates the laser melt pool, with surface\ntemperatures in agreement with in situ thermographic measurements on Inconel\n625. Geometric and thermal features of the simulated melt pools are extracted\nand used in subsequent mesoscale simulations. Solidification in the melt pool\nis simulated on two length scales. For the multicomponent alloy Inconel 625,\nmicrosegregation between dendrite arms is calculated using the Scheil-Gulliver\nsolidification model and DICTRA software. Phase-field simulations, using Ni-Nb\nas a binary analogue to Inconel 625, produced microstructures with primary\ncellular/dendritic arm spacings in agreement with measured spacings in\nexperimentally observed microstructures and a lesser extent of microsegregation\nthan predicted by DICTRA simulations. The composition profiles are used to\ncompare thermodynamic driving forces for nucleation against experimentally\nobserved precipitates identified by electron and X-ray diffraction analyses.\nOur analysis lists the precipitates that may form from FCC phase of enriched\ninterdendritic compositions and compares these against experimentally observed\nphases from 1 h heat treatments at two temperatures: stress relief at 1143 K\n(870{\\deg}C) or homogenization at 1423 K (1150{\\deg}C).",
        "positive": "Non-local cooperative atomic motions that govern dissipation in\n  amorphous tantala unveiled by dynamical mechanical spectroscopy: The mechanisms governing mechanical dissipation in amorphous tantala are\nstudied at microscopic scale via Molecular Dynamics simulations, namely by\nmechanical spectroscopy in a wide range of temperature and frequency. We find\nthat dissipation is associated with irreversible atomic rearrangements with a\nsharp cooperative character, involving tens to hundreds of atoms arranged in\nspatially extended clusters of polyhedra. Remarkably, at low temperature we\nobserve an excess of plastically rearranging oxygen atoms which correlates with\nthe experimental peak in the macroscopic mechanical losses. A detailed\nstructural analysis reveals preferential connections of the irreversibly\nrearranging polyhedra, corresponding to edge and face sharing. These results\nmight lead to microscopically informed design rules for reducing mechanical\nlosses in relevant materials for structural, optical, and sensing applications."
    },
    {
        "anchor": "Metallic Icosahedron Phase of Sodium at Terapascal Pressures: Alkali metals exhibit unexpected structures and electronic behavior at high\npressures. Compression of metallic sodium (Na) to 200 GPa leads to the\nstability of a wide-band-gap insulator with the double hexagonal hP4 structure.\nPost-hP4 structures remain unexplored, but they are important for addressing\nthe question of the pressure at which Na reverts to a metal. Here we report the\nreentrant metallicity of Na at the very high pressure of 15.5 terapascal (TPa),\npredicted using first-principles structure searching simulations. Na is\ntherefore insulating over the large pressure range of 0.2-15.5 TPa. Unusually,\nNa adopts an oP8 structure at pressures of 117-125 GPa, and the same oP8\nstructure at 1.75-15.5 TPa. Metallization of Na occurs on formation of a stable\nand striking body-centered cubic cI24 electride structure consisting of Na12\nicosahedra, each housing at its center about one electron which is not\nassociated with any Na ions.",
        "positive": "Size Effects of Ferroelectric and Magnetoelectric Properties of\n  Semi-ellipsoidal Bismuth Ferrite Nanoparticles: Bismuth ferrite (BiFeO3) is one of the most promising multiferroics with a\nsufficiently high ferroelectric (FE) and antiferromagnetic transition\ntemperatures, and magnetoelectric (ME) coupling coefficient at room\ntemperature, and thus it is highly sensitive to the impact of cross-influence\nof applied electric and magnetic fields. According to the urgent demands of\nnanotechnology miniaturization for ultra-high density data storage in advanced\nnonvolatile memory cells, it is very important to reduce the sizes of\nmultiferroic nanoparticles in the self-assembled arrays without serious\ndeterioration of their properties. We study size effects of the phase diagrams,\nFE and ME properties of semi-ellipsoidal BiFeO3 nanoparticles clamped to a\nrigid conductive substrate. The spatial distribution of the spontaneous\npolarization vector inside the nanoparticles, phase diagrams and\nparamagnetoelectric (PME) coefficient were calculated in the framework of\nmodified Landau-Ginzburg-Devonshire (LGD) approach. Analytical expressions were\nderived for the dependences of the FE transition temperature, average\npolarization, linear dielectric susceptibility and PME coefficient on the\nparticle sizes for a general case of a semi-ellipsoidal nanoparticles with\nthree different semi-axes a, b and height c. The analyses of the obtained\nresults leads to the conclusion that the size effect of the phase diagrams,\nspontaneous polarization and PME coefficient is rather sensitive to the\nparticle sizes aspect ratio in the polarization direction, and less sensitive\nto the absolute values of the sizes per se."
    },
    {
        "anchor": "Spin-orbit coupling effect in (Ga,Mn)As films: anisotropic exchange\n  interactions and magnetocrystalline anisotropy: The magneto-crystalline anisotropy (MCA) of (Ga,Mn)As films has been studied\non the basis of ab-initio electronic structure theory by performing magnetic\ntorque calculations. An appreciable contribution to the in-plane uniaxial\nanisotropy can be attributed to an extended region adjacent to the surface.\nCalculations of the exchange tensor allow to ascribe a significant part to the\nMCA to the exchange anisotropy, caused either by a tetragonal distortion of the\nlattice or by the presence of the surface or interface.",
        "positive": "Proper and improper chiral magnetic interactions: Atomistic spin models are of great value for predicting and understanding the\nmagnetic properties of real materials, and extensions of the existing models\nopen routes to new physics and potential applications. The\nDzyaloshinskii-Moriya interaction is the prototype for chiral magnetic\ninteractions, and several recent works have uncovered or proposed various types\nof generalized chiral interactions. However, in some cases the proposed\ninteractions or their interpretation do not comply with basic principles such\nas being independent of the magnetic configuration from which they are\nevaluated, or even obeying time-reversal invariance. In this letter, we present\na simple explanation for the origin of these puzzling findings, and point out\nhow to resolve them."
    },
    {
        "anchor": "Dynamic of a non homogeneously coarse grained system: To study materials phenomena simultaneously at various length scales,\ndescriptions in which matter can be coarse grained to arbitrary levels, are\nnecessary. Attempts to do this in the static regime (i.e. zero temperature)\nhave already been developed. In this letter, we present an approach that leads\nto a dynamics for such coarse-grained models. This allows us to obtain\ntemperature-dependent and transport properties. Renormalization group theory is\nused to create new local potentials model between nodes, within the\napproximation of local thermodynamical equilibrium. Assuming that these\npotentials give an averaged description of node dynamics, we calculate thermal\nand mechanical properties. If this method can be sufficiently generalized it\nmay form the basis of a Molecular Dynamics method with time and spatial\ncoarse-graining.",
        "positive": "Isothermal anisotropic magnetoresistance in antiferromagnetic metallic\n  IrMn: Antiferromagnetic spintronics is an emerging field; antiferromagnets can\nimprove the functionalities of ferromagnets with higher response times, and\nhaving the information shielded against external magnetic field. Moreover, a\nlarge list of aniferromagnetic semiconductors and metals with N\\'eel\ntemperatures above room temperature exists. In the present manuscript, we\npersevere in the quest for the limits of how large can anisotropic\nmagnetoresistance be in antiferromagnetic materials with very large spin-orbit\ncoupling. We selected IrMn as a prime example of first-class moment (Mn) and\nspin-orbit (Ir) combination. Isothermal magnetotransport measurements in an\nantiferromagnetic-metal(IrMn)/ferromagnetic-insulator thin film bilayer have\nbeen performed. The metal/insulator structure with magnetic coupling between\nboth layers allows the measurement of the modulation of the transport\nproperties exclusively in the antiferromagnetic layer. Anisotropic\nmagnetoresistance as large as 0.15 % has been found, which is much larger than\nthat for a bare IrMn layer. Interestingly, it has been observed that\nanisotropic magnetoresistance is strongly influenced by the field cooling\nconditions, signaling the dependence of the found response on the formation of\ndomains at the magnetic ordering temperature."
    },
    {
        "anchor": "Giant magnetic anisotropy of transition-metal dimers on defected\n  graphene: Continuous miniaturization of magnetic units in spintronics and quantum\ncomputing devices inspires efforts to search for magnetic nanostructures with\nlarge magnetic anisotropy energy (MAE). Typical nanostructures including\nmolecular magnets, magnetic nanoclusters and magnetic nanowires have MAEs of a\nfew meV so their blocking temperature is mostly lower than 50 K. In this work,\nwe demonstrated the feasibility of achieving giant MAE in systems with\ntransition metal dimers on defected and decorated graphene, based on density\nfunctional theory calculations. In particular, either a Pt-Ir dimer on a single\nvacancy or an Os-Ru dimer on a nitrogen-decorated divacancy possesses an MAE\nlarger than 60 meV and high structural stability. Interestingly, their magnetic\nanisotropy can be conveniently manipulated by using external electric field.\nThese features make them good candidates for the use in room temperature\nspintronics and quantum computing devices.",
        "positive": "Atomic resolution imaging of the two-component Dirac-Landau levels in a\n  gapped graphene monolayer: The wavefunction of massless Dirac fermions is a two-component spinor. In\ngraphene, a one-atom-thick film showing two-dimensional Dirac-like electronic\nexcitations, the two-component representation reflects the amplitude of the\nelectron wavefunction on the A and B sublattices. This unique property provides\nunprecedented opportunities to image the two components of massless Dirac\nfermions spatially. Here we report atomic resolution imaging of the\ntwo-component Dirac-Landau levels in a gapped graphene monolayer by scanning\ntunnelling microscopy and spectroscopy. A gap of about 20 meV, driven by\ninversion symmetry breaking by the substrate potential, is observed in the\ngraphene on both SiC and graphite substrates. Such a gap splits the n = 0\nLandau level (LL) into two levels, 0+ and 0-. We demonstrate that the amplitude\nof the wavefunction of the 0- LL is mainly at the A sites and that of the 0+ LL\nis mainly at the B sites of graphene, characterizing the internal structure of\nthe spinor of the n = 0 LL. This provides direct evidence of the two-component\nnature of massless Dirac fermions."
    },
    {
        "anchor": "Enhancement of magnetoresistance in manganite multilayers: Magnanite multilayers have been fabricated using La0.67Ca0.33MnO3 as the\nferromagnetic layer and Pr0.7Ca0.3MnO3 and Nd0.5Ca0.5MnO3 as the spacer layers.\nAll the multilayers were grown on LaAlO3 (100) by pulse laser deposition. An\nenhanced magnetoresistnace (defined (RH- R0)/R0) of more than 98% is observed\nin these multilayers. Also a low field magnetoresistance of 41% at 5000 Oe is\nobserved in these multilayer films. The enhanced MR is attributed to the\ninduced double exchange in the spacer layer, which is giving rise to more\nnumber of conducting carriers. This is compared by replacing the spacer layer\nwith LaMnO3 where Mn exists only in 3+ state and no enhancement is observed in\nthe La0.67Ca0.33MnO3 / LaMnO3 multilayers as double exchange mechanism can not\nbe induced by external magnetic fields.",
        "positive": "The role of ion transport phenomena in memristive double barrier devices: In this work we report on the role of ion transport for the dynamic behavior\nof a double barrier quantum mechanical\nAl/Al$_2$O$_3$/Nb$_{\\text{x}}$O$_{\\text{y}}$/Au memristive device based on\nnumerical simulations in conjunction with experimental measurements. The device\nconsists of an ultra-thin Nb$_{\\text{x}}$O$_{\\text{y}}$ solid state electrolyte\nbetween an Al$_2$O$_3$ tunnel barrier and a semiconductor metal interface at an\nAu electrode. It is shown that the device provides a number of interesting\nfeatures for potential applications such as an intrinsic current compliance, a\nrelatively long retention time, and no need for an initialization step.\nTherefore, it is particularly attractive for applications in highly dense\nrandom access memories or neuromorphic mixed signal circuits. However, the\nunderlying physical mechanisms of the resistive switching are still not\ncompletely understood yet. To investigate the interplay between the current\ntransport mechanisms and the inner atomistic device structure a lumped element\ncircuit model is consistently coupled with 3D kinetic Monte Carlo model for the\nion transport. The simulation results indicate that the drift of charged point\ndefects within the Nb$_{\\text{x}}$O$_{\\text{y}}$ is the key factor for the\nresistive switching behavior. It is shown in detail that the diffusion of\noxygen modifies the local electronic interface states resulting in a change of\nthe interface properties of the double barrier device."
    },
    {
        "anchor": "Superionic hydrogen in Earth's deep interior: Superionic hydrogen was previously thought to be an exotic state predicted\nand confirmed only in pure H2O ice. In Earth's deep interior, H2O exists in the\nform of O-H groups in ultra-dense hydrous minerals, which have been proved to\nbe stable even at the conditions of the core-mantle boundary (CMB). However,\nthe superionic states of these hydrous minerals at high P-T have not been\ninvestigated. Using first-principles calculations, we found that pyrite\nstructured FeO2Hx (0 <= x <= 1) and d-AlOOH, which have been proposed to be\nmajor hydrogen-bearing phases in the deep lower mantle (DLM), contain\nsuperionic hydrogen at high P-T conditions. Our observations indicate a\nuniversal pathway of the hydroxyl O-H at low pressure transforming to\nsymmetrical O-H-O bonding at high-P low-T, and a superionic state at high-P\nhigh-T. The superionicity of hydrous minerals has a major impact on the\nelectrical conductivity and hydrogen transportation behaviors of Earth's lower\nmantle as well as the CMB.",
        "positive": "First Principle Study of Magnetism and Magneto-structural Coupling in\n  Gallium Ferrite: We report a first-principles study of the magnetic properties, site disorder\nand magneto-structural coupling in multiferroic gallium ferrite (GFO) using\nlocal spin density approximation (LSDA+U) of density functional theory. The\ncalculations of the ground state A-type antiferromagnetic structure predict\nmagnetic moments consistent with the experiments whilst consideration of\nspin-orbit coupling yields a net orbital moment of ~ 0.025 Bohr magneton/Fe\nsite also in good accordance with the experiments. We find that though site\ndisorder is not spontaneous in the ground state, interchange between Fe2 and\nGa2 sites is most favored in the disordered state. The results show that\nferrimagnetism in GFO is due to Ga-Fe site disordering such that Fe spins at\nGa1 and Ga2 sites are antiferromagnetically aligned while maintaining\nferromagnetic coupling between Fe spins at Ga1 and Fe1 sites as well as between\nFe spins at Ga2 and Fe2 sites. The effect of spin configuration on the\nstructural distortion clearly indicates presence of magneto-structural coupling\nin GFO."
    },
    {
        "anchor": "Finite size and intrinsic field effect on the polar-active properties of\n  the ferroelectric-semiconductor heterostructures: Using Landau-Ginzburg-Devonshire approach we calculated the equilibrium\ndistributions of electric field, polarization and space charge in the\nferroelectric-semiconductor heterostructures containing proper or incipient\nferroelectric thin films. The role of the polarization gradient and intrinsic\nsurface energy, interface dipoles and free charges on polarization dynamics are\nspecifically explored. The intrinsic field effects, which originated at the\nferroelectric-semiconductor interface, lead to the surface band bending and\nresult into the formation of depletion space-charge layer near the\nsemiconductor surface. During the local polarization reversal (caused by the\ninhomogeneous electric field induced by the nanosized tip of the Scanning Probe\nMicroscope (SPM) probe) the thickness and charge of the interface layer\ndrastically changes, it particular the sign of the screening carriers is\ndetermined by the polarization direction. Obtained analytical solutions could\nbe extended to analyze polarization-mediated electronic transport.",
        "positive": "Pressure-induced isostructural phase transition of metal-doped silicon\n  clathrates: We propose an atomistic model for the pressure-induced isostructural phase\ntransition of metal-doped silicon clathrates, Ba8Si46 and K8Si46, that has been\nobserved at 14 GPa and 23 GPa, respectively. The model explains successfully\nthe equation of state, transition pressure, change of Raman spectra and\ndependence on the doped cations as well as the effects of substituting Si(6c)\natoms with noble metals."
    },
    {
        "anchor": "A Turing instability in the solid state: void lattices in irradiated\n  metals: Turing (or double-diffusive) instabilities describe pattern formation in\nreaction-diffusion systems, and were proposed in 1952 as a potential mechanism\nbehind pattern formation in nature, such as leopard spots and zebra stripes.\nBecause the mechanism requires the reacting species to have significantly\ndifferent diffusion rates, only a few liquid phase chemical reaction systems\nexhibiting the phenomenon have been discovered. In solids the situation is\nmarkedly different, since species such as impurities or other defects typically\nhave diffusivities $\\propto\\!\\exp\\left( -E/k_{\\rm B} T\\right)$, where $E$ is\nthe migration barrier and $T$ is the temperature. This often leads to diffusion\nrates differing by several orders of magnitude. Here we use a simple, minimal\nmodel to show that an important class of emergent patterns in solids, namely\nvoid superlattices in irradiated metals, could also be explained by the Turing\nmechanism. Analytical results are confirmed by phase field simulations. The\nmodel (Cahn-Hilliard equations for interstitial and vacancy concentrations,\ncoupled by creation and annihilation terms) is generic, and the mechanism could\nalso be responsible for the patterns and structure observed in many solid state\nsystems.",
        "positive": "Raman spectroscopy of monolayer to bulk PtSe2 exfoliated crystals: Raman spectroscopy is widely used to assess the quality of 2D materials thin\nfilms. This report focuses on $\\rm{PtSe_2}$, a noble transition metal\ndichalcogenide which has the remarkable property to transit from a\nsemi-conductor to a semi-metal with increasing layer number. While\npolycrystalline $\\rm{PtSe_2}$ can be grown with various crystalline qualities,\ngetting insight into the monocrystalline intrinsic properties remains\nchallenging. We report on the study of exfoliated 1 to 10 layers $\\rm{PtSe_2}$\nby Raman spectroscopy, featuring record linewidth. The clear Raman signatures\nallow layer-thickness identification and provides a reference metrics to assess\ncrystal quality of grown films."
    },
    {
        "anchor": "Nano-scale collinear multi-Q states driven by higher-order interactions: Complex magnetic order arises due to the competition of different\ninteractions between the magnetic moments. Recently, there has been an\nincreased interest in such states not only to unravel the fundamental physics\ninvolved, but also with regards to applications exploiting their unique\ninterplay with moving electrons. Whereas it is the Dzyaloshinskii-Moriya\ninteraction (DMI) that has attracted much attention because of its nature to\ninduce non-collinear magnetic order including magnetic-field stabilized\nskyrmions, it is the frustration of exchange interactions that can drive\nmagnetic order down to the nano-scale. On top of that, interactions between\nmultiple spins can stabilize two-dimensional magnetic textures as zero-field\nground states, known as multi-Q states. Here, we introduce a two-dimensional\nitinerant magnet with various competing atomic-scale magnetic phases. Using\nspin-polarized scanning tunneling microscopy we observe several zero-field\nuniaxial or hexagonal nano-scale magnetic states. First-principles calculations\ntogether with an atomistic spin model reveal that these states are stabilized\nby the interplay of frustrated exchange and higher-order interactions while the\nDMI is weak. Unexpectedly, it is found that not only non-collinear magnetic\nstates arise, but that higher-order interactions can also lead to collinear\nnano-scale multi-Q states.",
        "positive": "Features of synthesis of TbCr$_3$(BO$_3$)$_4$ single crystals by\n  solution-melt method: The phase formation of terbium chromium borate in melt solutions based on\nbismuth trimolybdate and lithium tungstate was studied. It was shown that there\nis no trigonal phase of terbium chromium borate in a system based on bismuth\ntrimolybdate at all component ratios. The ratio of components of a system based\non lithium tungstate has been found, at which trigonal TbCr$_3$(BO$_3$)$_4$\ncrystals are formed at temperatures above 1100$^\\circ$C, and below this\ntemperature only a monoclinic phase is formed. The X-ray properties of the\ngrown crystals were studied."
    },
    {
        "anchor": "Synthesis and properties of Co-doped titanate nanotubes and their\n  optical sensitization with methylene blue: Here we report on a novel chemical route to synthesize homogenous cobalt\ndoped titanate nanotubes (CoTNT), using an amorphous Co-doped precursor. The\ninfluence of the synthesis temperature, autoclave dwell time and metal doping\non the structural and microstructural as well as on the optical properties of\nthe synthesized titanate nanotubes is studied and discussed. The optical band\ngaps of the CoTNT samples are red shifted in comparison with the values\ndetermined for the undoped samples, such red shifts bringing the absorption\nedge of the CoTNT samples into the visible region. CoTNT materials also\ndemonstrate particular high adsorption ability for methylene blue, the amount\nof the adsorbed dye being higher than the one predictable for a monolayer\nformation. This suggests the possibility of intercalation of the dye molecule\nbetween the TiO6 layers of the TNT structure. It is also shown that the\nmethylene blue sensitized Co-doped nanostructures are highly stable under UV\nradiation and present a strong and broad absorption in the visible region.",
        "positive": "Hundreds of new, stable, one-dimensional materials from a generative\n  machine learning model: We use a generative neural network model to create thousands of new,\none-dimensional materials. The model is trained using 508 stable\none-dimensional materials from the Computational 1D Materials Database (C1DB)\ndatabase. More than 500 of the new materials are shown with density functional\ntheory calculations to be dynamically stable and with heats of formation within\n0.2 eV of the convex hull of known materials. Some of the new materials could\nalso have been obtained by chemical element substitution in the training\nmaterials, but completely new classes of materials are also produced. The band\nstructures, electronic densities of states, work functions, effective masses,\nand phonon spectra of the new materials are calculated, and the data are added\nto C1DB."
    },
    {
        "anchor": "Hypothesis-Driven Automated Experiment in Scanning Probe Microscopy:\n  Exploring the Domain Growth Laws in Ferroelectric Materials: We report the development and implementation of a hypothesis learning based\nautomated experiment, in which the microscope operating in the autonomous mode\nidentifies the physical laws behind the material's response. Specifically, we\nexplore the bias induced transformations that underpin the functionality of\nbroad classes of devices and functional materials from batteries and memristors\nto ferroelectrics and antiferroelectrics. Optimization and design of these\nmaterials require probing the mechanisms of these transformations on the\nnanometer scale as a function of the broad range of control parameters such as\napplied potential and time, often leading to experimentally intractable\nscenarios. At the same time, often the behaviors of these systems are\nunderstood within potentially competing theoretical models, or hypotheses.\nHere, we develop a hypothesis list that covers the possible limiting scenarios\nfor the domain growth, including thermodynamic, domain wall pinning, and\nscreening limited. We further develop and experimentally implement the\nhypothesis driven automated experiment in Piezoresponse Force Microscopy,\nautonomously identifying the mechanisms of the bias induced domain switching.\nThis approach can be applied for a broad range of physical and chemical\nexperiments with relatively low dimensional control parameter space and for\nwhich the possible competing models of the system behavior that ideally cover\nthe full range of physical eventualities are known or can be created. These\ninclude other scanning probe microscopy modalities such as force distance curve\nmeasurements and nanoindentation, as well as materials synthesis and\noptimization.",
        "positive": "Memory effect of Mn$_5$Ge$_3$ nanomagnets embedded inside a Mn-diluted\n  Ge matrix: Crystalline Mn5Ge3 nanomagnets are formed inside a Mn-diluted Ge matrix using\nMn ion implantation. A temperature-dependent memory effect and slow magnetic\nrelaxation are observed below the superparamagnetic blocking temperature of\nMn5Ge3. Our findings corroborate that the observed spin-glass-like features are\ncaused by the size distribution of Mn5Ge3 nanomagnets, rather than by the\ninter-particle interaction through the Mn-diluted Ge matrix."
    },
    {
        "anchor": "Magnetoelastic-magnetoelectric phase transitions in multiferroic BiFeO3: Our measured dielectric constant and mechanical response of multiferroic\nBiFeO3 indicate four phase transitions below room temperature. Features\ncorrelate with those reported at 50K (from a peak in the zero-field-cooled\nmagnetic susceptibility) and 230K (from splitting between field-cooled and\nzero-field-cooled magnetic data[1], and 200K (from magnon light scattering\ncross sections[2]). The primary order parameter is not the polarization in any\nof the low-T transitions. Instead, the transition near 230 K shows strong\nelastic coupling, while that at 50K is fundamentally magnetic, but\nmagnetostrictively coupled to the the lattice. The low-T phase transitions\ndisplay glassy behaviour. A further anomaly at 140K interpreted as spin\nreorientation[2,3] shows only weakly in dielectric and mechanical studies,\nindicating that it is predominantly magnetic with little coupling to any of the\nother order parameters.",
        "positive": "On the Elastic Properties and Fracture Patterns of MoX2 (X = S, Se, Te)\n  Membranes: A Reactive Molecular Dynamics Study: We carried out fully-atomistic reactive molecular dynamics simulations to\nstudy the elastic properties and fracture patterns of transition metal\ndichalcogenide (TMD) MoX2 (X=S, Se, Te) membranes, in their 2H and 1T phases,\nwithin the framework of the Stillinger-Weber potential. Results showed that the\nfracture mechanism of these membranes occurs through a fast crack propagation\nfollowed by their abrupt rupture into moieties. As a general trend, the\ntranslated arrangement of the chalcogen atoms in the 1T phase contributes to\ndiminishing their structural stability when contrasted with the 2H one. Among\nthe TMDs studied here, 2H-MoSe2 has a higher tensile strength (25.98 GPa)."
    },
    {
        "anchor": "Micromagnetic understanding of current-driven domain wall motion in\n  patterned nanowires: In order to explain recent experiments reporting a motion of magnetic domain\nwalls (DW) in nanowires carrying a current, we propose a modification of the\nspin transfer torque term in the Landau-Lifchitz-Gilbert equation. We show that\nit explains, with reasonable parameters, the measured DW velocities as well as\nthe variation of DW propagation field under current. We also introduce\ncoercivity by considering rough wires. This leads to a finite DW propagation\nfield and finite threshold current for DW propagation, hence we conclude that\nthreshold currents are extrinsic. Some possible models that support this new\nterm are discussed.",
        "positive": "Memory and aging effects in interacting sub-10nm nanomagnets with large\n  uniaxial anisotropy: Using a nonequilibrium Monte Carlo method suitable to nanomagnetism, we\ninvestigate representative systems of interacting sub-10nm grained nanomagnets\nwith large uniaxial anisotropy. Various magnetization memory and aging effects\nare found in such systems. We explain these dynamical effects using the\ndistributed relaxation times of the interacting nanomagnets due to their large\nanisotropy energies."
    },
    {
        "anchor": "Persistent double layer formation in kesterite solar cells: a critical\n  review: In kesterite CZTSSe solar cell research, an asymmetric crystallization\nprofile is often obtained after annealing, resulting in a bilayered or\ndouble-layered absorber. So far, only segregated pieces of research exist to\ncharacterize this double layer, its formation dynamics and its effect on the\nperformance of devices. Here, we review the existing research on double-layered\nkesterites and evaluate the different mechanisms proposed. Using a\ncosputtering-based approach, we show that the two layers can differ\nsignificantly in morphology, composition and optoelectronic properties, and\ncomplement the results with a statistical dataset of over 850 individual CZTS\nsolar cells. By reducing the absorber thickness from above 1000 nm to 300 nm,\nwe show that the double layer segregation is alleviated. In turn, we see a\nprogressive improvement in the device performance for lower thickness, which\nalone would be inconsistent with the known case of ultrathin CIGS solar cells.\nBy comparing the results with CZTS grown on monocrystalline Si substrates,\nwithout a native Na supply, we show that the alkali metal supply does not\ndetermine the double layer formation, but merely reduces the threshold for its\noccurrence. Instead, we propose that the main formation mechanism is the early\nmigration of Cu to the surface during annealing and formation of Cu2-xS phases,\nin a self-regulating process akin to the Kirkendall effect. We comment on the\ngenerality of the mechanism proposed, comparing our results to other synthesis\nroutes, including our own in-house results from solution processing and pulsed\nlaser deposition of sulfide and oxide-based targets. Although the double layer\noccurrence largely depends on the kesterite synthesis route, the common factors\ndetermining the double layer occurrence appear to be the presence of metallic\nCu and/or a chalcogen deficiency in the precursor matrix.",
        "positive": "Imaging three phases of Iodine on Ag (111) using low-temperature\n  scanning tunneling microscopy: We investigated the adsorption of iodine on silver (111) in ultra-high\nvacuum. Using low-temperature scanning tunneling microscopy (LT-STM)\nmeasurements we catalog the complex surface structures on the local scale. We\nidentified three distinct phases with increasing iodine coverage which we\ntentatively associate with three phases previously reported in LEED experiments\n(sqrt(3)x sqrt(3)R30, \"triangular\", \"hexagonal\"). We used Fourier space and\nreal space analysis to fully characterize each phase. While Fourier analysis\nmost easily connects our measurements to previous LEED studies, the real space\ninspection reveals local variations in the superstructures of the \"hexagonal\"\nand \"triangular\" phase. The latter, observed here for the first time by LT-STM,\nstabilized by one or two adatoms sitting at the center of a rosette-like iodine\nreconstruction. The most stunning discovery is that variation in the adatom\nseparation of the \"triangular\" phase reconstruct the Ag (111) surface lattice."
    },
    {
        "anchor": "Diffusion quantum Monte Carlo study of the equation of state and point\n  defects in aluminum: The many-body diffusion quantum Monte Carlo (DMC) method with twist-averaged\nboundary conditions is used to calculate the ground-state equation of state and\nthe energetics of point defects in fcc aluminum using supercells up to 1331\natoms. The DMC equilibrium lattice constant differs from experiment by 0.008 A,\nor 0.2%, while the cohesive energy using DMC with backflow wave functions with\nimproved nodal surfaces differs by 27 meV. DMC-calculated defect formation and\nmigration energies agree with available experimental data, except for the\nnearest-neighbor divacancy, which is found to be energetically unstable, in\nagreement with previous density functional theory (DFT) calculations. DMC and\nDFT calculations of vacancy defects are in reasonably close agreement.\nSelf-interstitial formation energies have larger differences between DMC and\nDFT, of up to 0.33eV, at the tetrahedral site. We also computed formation\nenergies of helium interstitial defects where energies differed by up to\n0.34eV, also at the tetrahedral site. The close agreement with available\nexperiments demonstrates that DMC can be used as a predictive method to obtain\nbenchmark energetics of defects in metals.",
        "positive": "Switching between Magnetic Bloch and N\u00e9el Domain Walls with Anisotropy\n  Modulations: It has been shown previously that the presence of a Dzyaloshinskii-Moriya\ninteraction in perpendicularly magnetized thin films stabilizes N\\'eel type\ndomain walls. We demonstrate, using micromagnetic simulations and analytical\nmodeling, that the presence of a uniaxial in-plane magnetic anisotropy can also\nlead to the formation of N\\'eel walls in the absence of a Dzyaloshinskii-Moriya\ninteraction. It is possible to abruptly switch between Bloch and N\\'eel walls\nvia a small modulation of both the in-plane, but also the perpendicular\nmagnetic anisotropy. This opens up a route towards electric field control of\nthe domain wall type with small applied voltages through electric field\ncontrolled anisotropies."
    },
    {
        "anchor": "Ethylene Carbonate Adsorption and Decomposition on Pristine and\n  Defective ZnO (1010) Surface: A First-Principles Study: Fundamental understanding of the reactivity between coating material of\nLi-ion battery cathode and electrolyte is important in order to obtain suitable\ncoating candidates. Herein, we study ethylene carbonate (EC) adsorption and\ndecomposition reactions on pristine, O vacancy- and Zn vacancy-defected ZnO\n(10-10) by means of first-principles density functional theory (DFT)\ncalculations. Possible decomposition pathways via H-abstraction and EC\nring-opening reaction that leads to the generation of CO2 and C2H4 gases are\nstudied from the thermodynamic and kinetic aspects. Firstly, we find that\nmolecular EC preferably adsorbs on both pristine and defective ZnO (1010) via\nthe bonding between its carbonyl oxygen (OC) and surface Zn. Secondly,\nsubsequent decomposition reactions show large tendency of EC to decompose on\nboth pristine and defective ZnO (10-10). This tendency is indicated by the\nlarge thermodynamic driving forces to decompose EC that range from -1.5 eV to\n-2.5 eV on both pristine and defective ZnO (10-10) (calculated with respect to\nEC gas phase). The large tendency of EC to decompose, however, is hindered by\nthe high activation barriers of the EC decomposition, shown by the lowest\nactivation barrier of 0.96 eV on Zn vacancy defected ZnO (10-10). Our results\nthus indicate that EC decomposition on ZnO (10-10) is mainly hindered due to\nits slow rate of decomposition instead of the thermodynamic factors.",
        "positive": "Achieving highly strengthened Al-Cu-Mg alloy by grain refinement and\n  grain boundary segregation: An age-hardenable Al-Cu-Mg alloy (A2024) was processed by high-pressure\ntorsion (HPT) for producing an ultrafine-grained structure. The alloy was\nfurther aged for extra strengthening. The tensile strength then reached a value\nas high as ~1 GPa. The microstructures were analyzed by transmission electron\nmicroscopy and atom probe tomography. The mechanism for the high strength was\nclarified in terms of solid-solution hardening, cluster hardening, work\nhardening, dispersion hardening and grain boundary hardening. It is shown that\nthe segregation of solute atoms at grain boundaries including subgrain\nboundaries plays a significant role for the enhancement of the tensile\nstrength."
    },
    {
        "anchor": "Effects of carrier mobility and morphology in organic semiconductor spin\n  valves: We studied spin transport in four organic semiconductors (OSCs) with\ndifferent electronic properties, with Fe and Co as the top and bottom\nferromagnetic (FM) contacts, respectively. Magnetoresistance (MR) effects were\nobserved up to room temperature in junctions based on an electron-carrying OSC,\ntris(8-hyroxyquinoline) aluminum (Alq$_3$) and a hole-carrying OSC, copper\nphthalocyanine (CuPc). The MR shows similar temperature dependence for these\ntwo OSCs, which suggests that the FM leads rather than the OSCs play a dominant\nrole on the spin-transport degradation with increasing temperature. We also\ninvestigated junctions based on two high lateral mobility electron-carrying\nOSCs, 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) and N,\nN'-bis(4-trifluoromethylbenzyl)-1,4,5,8-naphthalenetetracarboxylic diimide\n(CF$_3$-NTCDI). However, these junctions showed much weaker spin transport\neffects. Morphological studies suggest that these high mobility OSC films have\nmuch rougher surfaces than either Alq$_3$ or CuPc, therefore the degradation of\nspin transport may originate from enhanced scattering due to the rougher FM/OSC\ninterfaces. Our study shows that FM/OSC interfaces play an important role for\nspin transport in organic devices and need further exploration.",
        "positive": "Quasilattice-conserved optimization of the atomic structure of decagonal\n  Al-Co-Ni quasicrystals: The detailed atomic structure of quasicrystals has been an open question for\ndecades. Here, we present a quasilattice-conserved optimization method\n(quasiOPT), with particular quasiperiodic boundary conditions. As the atomic\ncoordinates described by basic cells and quasilattices, we are able to maintain\nthe self-similarity characteristics of qusicrystals with the atomic structure\nof the boundary region updated timely following the relaxing region.\nExemplified with the study of decagonal Al-Co-Ni (d-Al-Co-Ni), we propose a\nmore stable atomic structure model based on Penrose quasilattice and our\nquasiOPT simulations. In particular, \"rectangle-triangle\" rules are suggested\nfor the local atomic structures of d-Al-Co-Ni quasicrystals."
    },
    {
        "anchor": "Local Conduction at the BiFeO3-CoFe2O4 Tubular Oxide Interface: In strongly correlated oxides, heterointerfaces, manipulating the\ninteraction, frustration, and discontinuity of lattice, charge, orbital, and\nspin degrees of freedom, generate new possibilities for next generation\ndevices. In this study, we went back to examine the existing oxide\nheterostructures and found the local conduction at the BiFeO3-CoFe2O4 vertical\ninterface. In such hetero-nanostructure, the tubular interface, surrounding\nBiFeO3-CoFe2O4 vertical interface, can not only be the medium to the coupling\nbetween phases, but also be a new state of the matter. Our study demonstrates a\nnovel concept on oxide interface design and opens a pathway alternative for the\nexplorations of diverse functionalities in complex oxide interfaces.",
        "positive": "The influence of sonication on the thermal behavior of muscovite and\n  biotite: The differences on the thermal behavior (DTA-TG) of mica samples measured\nbefore and after sonication have been studied. Sonication treatment produces\nimportant modifications in the thermal behavior of muscovite and biotite\nsamples. For muscovite, it produces a broadening and decrease in temperature of\nthe dehydroxylation and crystallization effects, reaching a steady stage after\n40 h treatment time. For biotite, the original single peak profile for the\ndehydroxylation of the untreated sample is converted into a two peaks profile\nafter sonication, the intensity of the low temperature peak increases with\nsonication time, while the intensity of the high temperature peak decreases.\nThe modification of the thermal behavior for sonicated samples has been\ncorrelated to the particle size distribution effect produced by the sonication\ntreatment. It has been also observed that the cup tip of the sonication\nequipment contaminates the samples releasing titanium of its composition"
    },
    {
        "anchor": "Dependence of the electronic structure of the EuS/InAs interface on the\n  bonding configuration: Recently, the EuS/InAs interface has attracted attention for the possibility\nof inducing magnetic exchange correlations in a strong spin-orbit\nsemiconductor, which could be useful for topological quantum devices. We use\ndensity functional theory (DFT) with a machine-learned Hubbard $U$ correction\n[npj Comput. Mater. 6, 180 (2020)] to elucidate the effect of the bonding\nconfiguration at the interface on the electronic structure. For all interface\nconfigurations considered here, we find that the EuS valence band maximum (VBM)\nlies below the InAs VBM. In addition, dispersed states emerge at the top of the\nInAs VBM at the interface, which do not exist in either material separately.\nThese states are contributed mainly by the InAs layer adjacent to the\ninterface. They are localized at the interface and may be attributed to charge\ntransfer from the EuS to the InAs. The interface configuration affects the\nposition of the EuS VBM with respect to the InAs VBM, as well as the dispersion\nof the interface state. For all interface configurations studied here, the\ninduced magnetic moment in the InAs is small. This suggests that this\ninterface, in its coherent form studied here, is not promising for inducing\nequilibrium magnetic properties in InAs.",
        "positive": "Flexible MgO barrier magnetic tunnel junctions: Flexible electronic devices require the integration of multiple crucial\ncomponents on soft substrates to achieve their functions. In particular, memory\ndevices are the fundamental component for data storage and processing in\nflexible electronics. Here, we present flexible MgO barrier magnetic tunnel\njunction (MTJ) devices fabricated using a transfer printing process, which\nexhibit reliable and stable operation under substantial deformation of the\ndevice substrates. In addition, the flexible MTJ devices yield significantly\nenhanced tunneling magnetoresistance (TMR) of ~300 % and improved abruptness of\nswitching, as residual strain in the MTJ structure induced by the fabrication\nprocess is released during the transfer process. This approach could be useful\nfor a wide range of flexible electronic systems that require high performance\nmemory components."
    },
    {
        "anchor": "Adiabatic cross-polarization via intermediate dipolar-ordered state: It is experimentally demonstrated that an adiabatic demagnetization -\nremagnetization scheme, where the Zeeman order of abundant nuclei is first\nadiabatically converted into the dipolar order, and then, into the Zeeman order\nof rare nuclei, can significantly increase polarization of rare nuclei compared\nto the conventional cross-polarization technique.",
        "positive": "Multiferroic order parameters in rhombic antiferromagnets. RCrO$_3$: In this paper, we explore magneteoelectricity of rare earth orthochromites\nfrom the symmetry point of view. We determine the principal structural order\nparameters and find their couplings with ferroelectric and magnetic orderings.\nOur calculations showed that electric dipole moments emerge in the vicinity of\nCr3+ ions in the unit cell of RCrO3 due to the displacements of oxygen ions\nfrom their highly symmetric positions in the parent perovskite phase\n(structural instability). We find that the electric dipole moments are arranged\nin an antiferroelectric mode, so, in essence, RCrO3 are antiferroelectric\nmaterials. By classifying the order parameters according to the irreducible\nrepresentations of the RCrO3 symmetry group (D2h16), we determine the possible\ncouplings between distortive, ferroelectric and magnetic orderings and explore\nthe emerging magnetoelectric structures in these terms. Our analysis makes it\npossible to explain experimentally observed polarization reversal and the\nconcomitant reorientation of spins in a series of RCrO3 compounds and to\npredict the possible scenarios of phase transitions in RCrO3."
    },
    {
        "anchor": "Selective Control of Surface Spin Current in Topological Materials based\n  on Pyrite-type OsX2 (X = Se, Te) Crystals: Topological materials host robust surface states, which could form the basis\nfor future electronic devices. As such states have spins that are locked to the\nmomentum, they are of particular interest for spintronic applications.\nUnderstanding spin textures of the surface states of topologically nontrivial\nmaterials, and being able to manipulate their polarization, is therefore\nessential if they are to be utilized in future technologies. Here we use\nfirst-principles calculations to show that pyrite-type crystals OsX2 (X= Se,\nTe) are a class of topological material that can host surface states with spin\npolarization that can be either in-plane or out-of-plane. We show that the\nformation of low-energy states with symmetry-protected energy- and\ndirection-dependent spin textures on the (001) surface of these materials is a\nconsequence of a transformation from a topologically trivial to nontrivial\nstate, induced by spin orbit interactions. The unconventional spin textures of\nthese surface states feature an in-plane to out-of-plane spin polarization\ntransition in the momentum space protected by local symmetries. Moreover, the\nsurface spin direction and magnitude can be selectively filtered in specific\nenergy ranges. Our demonstration of a new class of topological material with\ncontrollable spin textures provide a platform for experimentalists to detect\nand exploit unconventional surface spin textures in future spin-based\nnanoelectronic devices.",
        "positive": "Significance of Off-Center Rattling for Emerging Low-lying THz Modes in\n  type-I Clathrates: We show that the distinct differences of low-lying THz-frequency dynamics\nbetween type-I clathrates with on-center and off-center guest ions naturally\nfollow from a theoretical model taking into account essential features of the\ndynamics of rattling guest ions. Our model analysis demonstrates the drastic\nchange from the conventional dynamics shown by on-center systems to the\npeculiar dynamics of off-center systems in a unified manner. We claim that\nglass-like plateau thermal conductivities observed for off-center systems stem\nfrom the flattening of acoustic phonon dispersion in the regime |k|<|G|/4. The\nmechanism is applicable to other systems such as glasses or relaxers."
    },
    {
        "anchor": "Composition-dependent interatomic potentials: A systematic approach to\n  modelling multicomponent alloys: We propose a simple scheme to construct composition-dependent interatomic\npotentials for multicomponent systems that when superposed onto the potentials\nfor the pure elements can reproduce not only the heat of mixing of the solid\nsolution in the entire concentration range but also the energetics of a wider\nrange of configurations including intermetallic phases. We show that an\nexpansion in cluster interactions provides a way to systematically increase the\naccuracy of the model, and that it is straightforward to generalise this\nprocedure to multicomponent systems. Concentration-dependent interatomic\npotentials can be built upon almost any type of potential for the pure elements\nincluding embedded atom method (EAM), modified EAM, bond-order, and\nStillinger-Weber type potentials. In general, composition-dependent N-body\nterms in the total energy lead to explicit (N+1)-body forces, which potentially\nrenders them computationally expensive. We present an algorithm that overcomes\nthis problem and that can speed up the calculation of the forces for\ncomposition-dependent pair potentials in such a way as to make them\ncomputationally comparable in efficiency and scaling behaviour to standard EAM\npotentials. We also discuss the implementation in Monte-Carlo simulations.\nFinally, we exemplarily review the composition-dependent EAM model for the\nFe-Cr system [PRL 95, 075702 (2005)].",
        "positive": "Nonadiabatic Born effective charges in metals and the Drude weight: In insulators, Born effective charges describe the electrical polarization\ninduced by the displacement of individual atomic sublattices. Such a physical\nproperty is at first sight irrelevant for metals and doped semiconductors,\nwhere the macroscopic polarization is ill-defined. Here we show that, in clean\nconductors, going beyond the adiabatic approximation results in nonadiabatic\nBorn effective charges that are well defined in the low-frequency limit. In\naddition, we find that the sublattice sum of the nonadiabatic Born effective\ncharges does not vanish as it does in the insulating case, but instead is\nproportional to the Drude weight. We demonstrate these formal results with\ndensity functional perturbation theory calculations of Al, and electron-doped\nSnS$_2$ and SrTiO$_3$."
    },
    {
        "anchor": "Atomically engineered cobaltite layers for robust ferromagnetism: Emergent phenomena at heterointerfaces are directly associated with the\nbonding geometry of adjacent layers. Effective control of accessible\nparameters, such as the bond length and bonding angles, offers an elegant\nmethod to tailor competing energies of the electronic and magnetic ground\nstates. In this study, we construct unit thick syntactic layers of cobaltites\nwithin a strongly tilted octahedral matrix via atomically precise synthesis.\nThe octahedral tilt patterns of adjacent layers propagate into cobaltites,\nleading to a continuation of octahedral tilting while maintaining significant\nmisfit tensile strain. These effects induce severe rumpling within an atomic\nplane of neighboring layers triggers the electronic reconstruction between the\nsplitting orbitals. First-principles calculations reveal that the cobalt ions\ntransits to a higher spin state level upon octahedral tilting, resulting in\nrobust ferromagnetism in ultrathin cobaltites. This work demonstrates a design\nmethodology for fine-tuning the lattice and spin degrees of freedom in\ncorrelated quantum heterostructures by exploiting epitaxial geometric\nengineering.",
        "positive": "Identifying Subcascades From The Primary Damage State Of Collision\n  Cascades: The morphology of a collision cascade is an important aspect in understanding\nthe formation of defects and their distribution. While the number of\nsubcascades is an essential parameter to describe the cascade morphology, the\nmethods to compute this parameter are limited. We present a method to compute\nthe number of subcascades from the primary damage state of the collision\ncascade. Existing methods analyse peak damage state or the end of ballistic\nphase to compute the number of subcascades which is not always available in\ncollision cascade databases. We use density based clustering algorithm from\nunsupervised machine learning domain to identify the subcascades from the\nprimary damage state. To validate the results of our method we first carry out\na parameter sensitivity study of the existing algorithms. The study shows that\nthe results are sensitive to input parameters and the choice of the time-frame\nanalyzed. On a database of 100 collision cascades in W, we show that the method\nwe propose, which analyzes primary damage state to predict number of\nsubcascades, is in good agreement with the existing method that works on the\npeak state. We also show that the number of subcascades found with different\nparameters can be used to classify and group together the cascades that have\nsimilar time-evolution and fragmentation."
    },
    {
        "anchor": "Field-effect transistors assembled from functionalized carbon nanotubes: We have fabricated field effect transistors from carbon nanotubes using a\nnovel selective placement scheme. We use carbon nanotubes that are covalently\nbound to molecules containing hydroxamic acid functionality. The functionalized\nnanotubes bind strongly to basic metal oxide surfaces, but not to silicon\ndioxide. Upon annealing, the functionalization is removed, restoring the\nelectronic properties of the nanotubes. The devices we have fabricated show\nexcellent electrical characteristics.",
        "positive": "Influence of heat flow directions on Nernst effects in Py/Pt bilayers: We investigated the voltages obtained in a thin Pt strip on a Permalloy film\nwhich was subject to in-plane temperature gradients and magnetic fields. The\nvoltages detected by thin W-tips or bond wires showed a purely symmetric effect\nwith respect to the external magnetic field which can be fully explained by the\nplanar Nernst effect (PNE). To verify the influence of the contacts\nmeasurements in vacuum and atmosphere were compared and gave similar results.\nWe explain that a slightly in-plane tilted temperature gradient only shifts the\nfield direction dependence but does not cancel out the observed effects.\nAdditionally, the anomalous Nernst effect (ANE) could be induced by using thick\nAu-tips which generated a heat current perpendicular to the sample plane. The\neffect can be manipulated by varying the temperature of the Au-tips. These\nmeasurements are discussed concerning their relevance in transverse spin\nSeebeck effect measurements."
    },
    {
        "anchor": "Thickness dependence of unidirectional spin-Hall magnetoresistance in\n  metallic bilayers: A nonlinear magnetoresistance - called unidirectional spin-Hall\nmagnetoresistance - is recently experimentally discovered in metallic bilayers\nconsisting of a heavy metal and a ferromagnetic metal. To study the fundamental\nmechanism of the USMR, both ferromagnetic and heavy metallic layer thickness\ndependence of the USMR are presented in a Pt/Co/AlOx trilayer at room\ntemperature. To avoid ambiguities, second harmonic Hall measurements are used\nfor separating spin-Hall and thermal contributions to the non-linear\nmagnetoresistance. The experimental results are fitted by using a\ndrift-diffusion theory, with parameters extracted from an analysis of\nlongitudinal resistivity of the Co layer within the framework of the\nFuchs-Sondheimer model. A good agreement with the theory is found,\ndemonstrating that the USMR is governed by both the spin-Hall effect in the\nheavy metallic layer and the metallic diffusion process in the ferromagnetic\nlayer.",
        "positive": "Polymers near Metal Surfaces: Selective Adsorption and Global\n  Conformations: We study the properties of a polycarbonate melt near a nickel surface as a\nmodel system for the interaction of polymers with metal surfaces by employing a\nmultiscale modeling approach. For bulk properties a suitably coarse grained\nbead spring model is simulated by molecular dynamics (MD) methods with model\nparameters directly derived from quantum chemical calculations. The surface\ninteractions are parameterized and incorporated by extensive quantum mechanical\ndensity functional calculations using the Car-Parrinello method. We find strong\nchemisorption of chain ends, resulting in significant modifications of the melt\ncomposition when compared to an inert wall."
    },
    {
        "anchor": "Generation of Intrinsic Vibrational Gap Modes in Three-Dimensional Ionic\n  Crystals: The existence of anharmonic localization of lattice vibrations in a perfect\n3-D diatomic ionic crystal is established for the rigid-ion model by molecular\ndynamics simulations. For a realistic set of NaI potential parameters, an\nintrinsic localized gap mode vibrating in the [111] direction is observed for\nfcc and zinc blende lattices. An axial elastic distortion is an integral\nfeature of this mode which forms more readily for the zinc blende than for the\nfcc structure. Molecular dynamics simulations verify that in each structure\nthis localized mode may be stable for at least 200 cycles.",
        "positive": "Lattice-mediated bulk flexoelectricity from first principles: We present the derivation and code implementation of a first-principles\nmethodology to calculate the lattice-mediated contributions to the bulk\nflexoelectric tensor. The approach is based on our recent analytical\nlong-wavelength extension of density-functional perturbation theory [Royo and\nStengel, Phys. Rev. X 9, 021050 (2019)], and avoids the cumbersome numerical\nderivatives with respect to the wave vector that were adopted in previous\nimplementations. To substantiate our results, we revisit and numerically\nvalidate the sum rules that relate flexoelectricity and uniform elasticity by\ngeneralizing them to regimes where finite forces and stresses are present. We\nalso revisit the definition of the elastic tensor under stress, especially in\nregards to the existing linear-response implementation. We demonstrate the\nperformance of our method by applying it to representative cubic crystals and\nto the tetragonal low-temperature polymorph of SrTiO$_3$, obtaining excellent\nagreement with the available literature data."
    },
    {
        "anchor": "Ultrafast generation and decay of a surface metal: Band bending at semiconductor surfaces induced by chemical doping or electric\nfields can create metallic surfaces with properties not found in the bulk, such\nas high electron mobility, magnetism or superconductivity. Optical generation\nof such metallic surfaces via BB on ultrafast timescales would facilitate a\ndrastic manipulation of the conduction, magnetic and optical properties of\nsemiconductors for high-speed electronics. Here, we demonstrate the ultrafast\ngeneration of a metal at the (10-10) surface of ZnO upon photoexcitation.\nCompared to hitherto known ultrafast photoinduced semiconductor-to-metal\ntransitions that occur in the bulk of inorganic semiconductors, the\nmetallization of the ZnO surface is launched by 3-4 orders of magnitude lower\nphoton fluxes. Using time- and angle-resolved photoelectron spectroscopy, we\nshow that the phase transition is caused by photoinduced downward surface band\nbending due to photodepletion of donor-type deep surface defects. At low photon\nflux, surface-confined excitons are formed. Above a critical exciton density, a\nMott transition occurs, leading to a partially filled metallic band below the\nequilibrium Fermi energy. This process is in analogy to chemical doping of\nsemiconductor surfaces. The discovered mechanism is not material-specific and\npresents a general route for controlling metallicity confined to semiconductor\ninterfaces on ultrafast timescales.",
        "positive": "Electronic structure and properties of lithium-rich complex oxides: Lithium-rich complex transition-metal oxides Li$_2$MoO$_3$, Li$_2$RuO$_3$,\nLi$_3$RuO$_4$, Li$_3$NbO$_4$, Li$_5$FeO$_4$, Li$_5$MnO$_4$ and their\nderivatives are of interest for high-capacity battery electrodes. Here, we\nreport a first-principles density-functional theory study of the atomic and\nelectronic structure of these materials using the Heyd-Scuseria-Ernzerhof (HSE)\nscreened hybrid functional which treats all orbitals in the materials on equal\nfooting. Dimerization of the transition-metal ions is found to occur in layered\nLi$_2$MoO$_3$, in both fully lithiated and partially delithiated compounds. The\nRu--Ru dimerization does not occur in fully lithiated Li$_2$RuO$_3$, in\ncontrast to what is commonly believed; Ru--Ru dimers are, however, found to\noccur in the presence of lithium vacancies caused by lithium loss during\nsynthesis and/or lithium removal during use. We also analyze the electronic\nstructure of the complex oxides and discuss the delithiation mechanism in these\nbattery electrode materials."
    },
    {
        "anchor": "Time-reversal symmetry breaking driven topological phase transition in\n  EuB$_6$: The interplay between time-reversal symmetry (TRS) and band topology plays a\ncrucial role in topological states of quantum matter. In\ntime-reversal-invariant (TRI) systems, the inversion of spin-degenerate bands\nwith opposite parity leads to nontrivial topological states, such as\ntopological insulators and Dirac semimetals. When the TRS is broken, the\nexchange field induces spin splitting of the bands. The inversion of a pair of\nspin-splitting subbands can generate more exotic topological states, such as\nquantum anomalous Hall insulators and magnetic Weyl semimetals. So far, such\ntopological phase transitions driven by the TRS breaking have not been\nvisualized. In this work, using angle-resolved photoemission spectroscopy, we\nhave demonstrated that the TRS breaking induces a band inversion of a pair of\nspin-splitting subbands at the TRI points of Brillouin zone in EuB$_6$, when a\nlong-range ferromagnetic order is developed. The dramatic changes in the\nelectronic structure result in a topological phase transition from a TRI\nordinary insulator state to a TRS-broken topological semimetal (TSM) state.\nRemarkably, the magnetic TSM state has an ideal electronic structure, in which\nthe band crossings are located at the Fermi level without any interference from\nother bands. Our findings not only reveal the topological phase transition\ndriven by the TRS breaking, but also provide an excellent platform to explore\nnovel physical behavior in the magnetic topological states of quantum matter.",
        "positive": "Crossover critical behavior of Ga1-xMnxAs: The critical behavior of Ga1-xMnxAs in a close vicinity of the Curie\ntemperature was experimentally studied by using the thermal diffusivity\nmeasurements. Taking into account that the inverse of the thermal diffusivity\nhas the same critical behavior as the specific heat, the critical exponent\n{\\alpha} for the samples investigated has been determined. With approaching\nclose to the critical temperature, the crossover from the mean-field-like to\nthe Ising-like critical behavior has been observed. From the crossover behavior\nthe values of the Ginzburg number and the exchange interaction length in\nGa1-xMnxAs with different concentrations of Mn were determined."
    },
    {
        "anchor": "Strain-induced interlayer magnetic coupling spike of two-dimensional van\n  der Waals material Fe$_5$GeTe$_2$: A stronger interlayer magnetic coupling (ILMC) can open up new opportunities\nin spintronics devices for Fe$_5$GeTe$_2$ (F5GT), a demonstrated\ntwo-dimensional (2D) van der Waals (vdW) material with high Currie temperature.\nHere we observe an extraordinary ILMC spike in F5GT, jumping from 1.15 to 12.79\nmeV/f.u, by applying a 3% in-plane strain. This spike is mainly ascribed to a\nsignificant increase in the magnetic moment of the Fe5 ion. Moreover, the\napplied in-plane strain can also significantly enhance the magnetic anisotropy\nenergy (MAE) of the system, triggering the transition between the in/off-plane\nconfigurations in multi-layer F5GT.",
        "positive": "Deep-potential enabled multiscale simulation of gallium nitride devices\n  on boron arsenide cooling substrates: High-efficient heat dissipation plays critical role for high-power-density\nelectronics. Experimental synthesis of ultrahigh thermal conductivity boron\narsenide (BAs, 1300 W m-1K-1) cooling substrates into the wide-bandgap\nsemiconductor of gallium nitride (GaN) devices has been realized. However, the\nlack of systematic analysis on the heat transfer across the BAs-GaN interface\nhampers the practical applications. In this study, by constructing the accurate\nand high-efficient machine learning interatomic potentials, we performed\nmultiscale simulations of the BAs-GaN heterostructures. Ultrahigh interfacial\nthermal conductance (ITC) of 265 MW m-2K-1 is achieved, which lies in the\nwell-matched lattice vibrations of BAs and GaN. Moreover, the competition\nbetween grain size and boundary resistance was revealed with size increasing\nfrom 1 nm to 100 {\\mu}m. Such deep-potential equipped multiscale simulations\nnot only promote the practical applications of BAs cooling substrates in\nelectronics, but also offer new approach for designing advanced thermal\nmanagement systems."
    },
    {
        "anchor": "Influence of ensemble boundary conditions (thermostat and barostat) on\n  the deformation of amorphous polyethylene by molecular dynamics: Molecular dynamics simulations are increasingly being used to investigate the\nstructural evolution of polymers during mechanical deformation, but relatively\nfew studies focus on the influence of boundary conditions on this evolution, in\nparticular the dissipation of both heat and pressure through the periodic\nboundaries during deformation. The research herein explores how the tensile\ndeformation of amorphous polyethylene, modelled with a united atom method\npotential, is influenced by heat and pressure dissipation. The stress-strain\ncurves for the pressure dissipation cases (uniaxial tension) are in qualitative\nagreement with experiments and show that heat dissipation has a large effect on\nthe strain hardening modulus calculated by molecular dynamics simulations. The\nevolution of the energy associated with bonded and non-bonded terms was\nquantified as a function of strain as well as the evolution of stress in both\nthe loading and non-loading directions to give insight into how the stress\nstate is altered within the elastic, yield, strain softening, and strain\nhardening regions. The stress partitioning shows a competition between\n`tensile' Van der Waal's interactions and `compressive' bond stretching forces,\nwith the characteristic yield stress peak clearly associated with the\nnon-bonded stress. The lack of heat dissipation had the largest effect on the\nstrain hardening regime, where an increase in the calculated temperature\ncorrelated with faster chain alignment in the loading direction and more rapid\nconformation changes. In part, these observations demonstrate the role that\nheat and pressure dissipation play on deformation characteristics of amorphous\npolymers, particularly for the strain hardening regime.",
        "positive": "Controlled synthesis and characterization of porous silicon\n  nanoparticles for dynamic nuclear polarization: Si nanoparticles (NPs) have been actively developed as a hyperpolarized\nmagnetic resonance imaging (MRI) agent with an imaging window of more than one\nhour. However, the progress in the development of NPs has been hampered by the\nincomplete understanding of their structural properties that correspond to\nefficient hyperpolarization build up and long polarization decays. In this work\nwe study dynamic nuclear polarization (DNP) of single crystal porous Si (PSi)\nNPs with defined doping densities ranging from nominally undoped to highly\ndoped with boron or phosphorus. To develop such PSi NPs we perform low-load\nmetal-assisted catalytic etching for electronic grade Si powder followed by\nthermal oxidation to form the dangling bonds in the $\\text{Si/SiO}_2$\ninterface, the $P_b$ centers, which are the endogenous source of the unpaired\nelectron spins necessary for DNP. The controlled fabrication and oxidation\nprocedures allow us to thoroughly investigate the impact of the magnetic field,\ntemperature and doping on the DNP process, as well as to identify the rate\nlimiting step for the polarization buildup and decay. We argue that the buildup\nand decay rate constants are limited by the polarization transfer across the\nnuclear spin diffusion barrier determined by the large hyperfine shift of the\ncentral \\textsuperscript{29}Si nuclei of the $P_b$ centers. Finally, we find\nthe room temperature relaxation of low boron doped PSi NPs reaching $75 \\pm 3$\nminutes and nuclear polarization levels exceeding $\\sim 6$ % when polarized at\n6.7 T and 1.4 K. Our study thus establishes solid grounds for further\ndevelopment of Si NPs."
    },
    {
        "anchor": "Engineered Defects to Modulate Fracture Strength of Single Layer MoS2:\n  An Atomistic Study: We use classical molecular dynamics (MD) simulations to investigate the\nmechanical properties of pre-cracked, nano-porous single layer MoS2 (SLMoS2)\nand the effect of interactions between cracks and pores. We found that the\nfailure of pre-cracked and nano-porous SLMoS2 is dominated by brittle type\nfracture. Bonds in armchair direction show a stronger resistance to crack\npropagation compared to the zigzag direction. We compared the brittle failure\nof Griffith prediction with the MD fracture strength and toughness and found\nsubstantial differences that limit the applicability of Griffith criterion for\nSLMoS2 in case of nano-cracks and pores. Next, we demonstrate that the\nmechanical properties of pre-cracked SLMoS2 can be enhanced via symmetrically\nplaced pores and auxiliary cracks around a central crack and position of such\narrangements can be optimized for maximum enhancement of strengths. Such a\nstudy would help towards strain engineering based advanced designing of SLMoS2\nand other similar Transition Metal Dichalcogenides.",
        "positive": "Characterization of silicon thin overlayers on rutile \\ce{TiO2}\n  (110)-(1x1): Silicon thin films for coverages ($\\theta$) between 0.3 and 3 monolayers have\nbeen grown on rutile \\ce{TiO2}(110)-(1x1) at room temperature and studied by\nx-ray and ultra-violet photoelectron spectroscopies, Auger electron\nspectroscopy, and low energy electron diffraction (LEED). A clear evidence of a\nstrong \\ce{Si}/\\ce{TiO2} interaction consistent with the high affinity of O for\nSi has been found. The Ti cations on the substrate are reduced, while the Si\nfilm is oxidized, yielding \\ce{SiO2} and a mixture of silicon suboxides.\nNeutral Si atoms are observed at a coverage of 3 monolayers. At the interface\nregion we observe the formation of cross-linking Ti-O-Si bonds. The thin Si\noverlayer strongly attenuates the $(1 \\times 1)$ LEED pattern from the\nsubstrate. Finally, thermal annealing results in the improvement of the\n\\ce{SiO2} stoichiometry, but the surface order is not recovered. Using\nab-initio density functional theory we have obtained optimum geometrical\nconfigurations and corresponding density of states for 1/3 \\le \\theta \\le 1$\nmonolayers of Si adsorbed on the $1 \\times 1$ two-dimensional unit cell."
    },
    {
        "anchor": "Spin injection through the depletion layer: a theory of spin-polarized\n  p-n junctions and solar cells: A drift-diffusion model for spin-charge transport in spin-polarized {\\it p-n}\njunctions is developed and solved numerically for a realistic set of material\nparameters based on GaAs. It is demonstrated that spin polarization can be\ninjected through the depletion layer by both minority and majority carriers,\nmaking all-semiconductor devices such as spin-polarized solar cells and bipolar\ntransistors feasible. Spin-polarized {\\it p-n} junctions allow for\nspin-polarized current generation, spin amplification, voltage control of spin\npolarization, and a significant extension of spin diffusion range.",
        "positive": "Novel Highly Active Pt/Graphene Catalyst for Cathodes of\n  Cu(II/I)-Mediated Dye-Sensitized Solar Cells: Novel highly active, optically-transparent electrode catalyst containing Pt,\nPtOx, graphene oxide and stacked graphene platelet nanofibers is developed for\na cathode of Cu(II/I)-mediated dye-sensitized solar cells."
    },
    {
        "anchor": "Growth Kinetic studies of ion beam sputtered AlN-thin films: Effect of\n  reactive assistance of nitrogen plasma: Reactive dual ion beam sputter deposition of AlN thin films was carried out\nfor the analysis of surface growth characteristics by Atomic Force Microscopy.\nThe variation of roughness as a function of deposition time was analysed by\nDynamic Scaling Theory (DST). Two distinct exponents, static and dynamic were\nused to unravel the film growth characteristics. As the deposition time\nincreased, static scaling exponent decreased gradually and substrate surface\ncoverage was increased which is indicated by a decrease in critical length Lc.\nThe rms roughness of the film was increased from 1.99 to 3.42 nm as the\ndeposition time was increased from 3 minutes to 15 minutes. Dynamic scaling\nexponent was found to be 0.36. During the growth, surface diffusion (n = 4)\nbecomes the major roughening phenomenon while Bulk diffusion (n = 3) turns into\nthe dominating smoothening phenomenon.",
        "positive": "Theoretical investigation of novel electronic, optical, mechanical and\n  thermal properties of metallic hydrogen at 495 GPa: Atomic metallic hydrogen has been produced in the laboratory at high pressure\nand low temperature, prompting further investigations of its different\nproperties. However, purely experimental approaches are infeasible because of\nthe extreme requirements in producing and preserving the metastable phase. Here\nwe perform a systematic investigation of the electronic, optical, mechanical\nand thermal properties of $I4_1/amd$ hydrogen at 495 GPa using first-principles\ncalculations. We calculate the electronic structure and dielectric function to\nverify the metallic behaviour of $I4_1/amd$ hydrogen. The calculated total\nplasma frequency from both intraband and interband transitions, 33.40 eV,\nagrees well with the experimental result. The mechanical properties including\nelastic stability and sound velocity are also investigated. The mechanical\nstability of $I4_1/amd$ hydrogen is limited by shear modulus other than bulk\nmodulus, and the high Young's modulus indicates that $I4_1/amd$ hydrogen is a\nstiff material. After investigating the lattice vibrational properties, we\nstudy the thermodynamical properties and lattice anharmonicity to understand\nthermal behaviours in metallic hydrogen. Finally, the lattice thermal\nconductivity of $I4_1/amd$ hydrogen is calculated to be 194.72 W/mK and 172.96\nW/mK along the $x$ and $z$ directions, respectively. Using metallic hydrogen as\nan example, we demonstrate that first-principles calculations can be a\ngame-changing solution to understand a variety of material properties in\nextreme conditions."
    },
    {
        "anchor": "Anomalous Hall effect in half-metallic Heusler compound Co$_{2}$Ti$X$\n  ($X$=Si, Ge): Though Weyl fermions have recently been observed in several materials with\nbroken inversion symmetry, there are very few examples of such systems with\nbroken time reversal symmetry. Various Co$_{2}$-based half-metallic\nferromagnetic Heusler compounds are lately predicted to host Weyl type\nexcitations in their band structure. These magnetic Heusler compounds with\nbroken time reversal symmetry are expected to show a large momentum space Berry\ncurvature, which introduces several exotic magneto-transport properties. In\nthis report, we present systematic analysis of experimental results on\nanomalous Hall effect (AHE) in Co$_2$Ti$X$ ($X$=Si and Ge). This study is an\nattempt to understand the role of Berry curvature on AHE in Co$_2$Ti$X$ family\nof materials. The anomalous Hall resistivity is observed to scale quadratically\nwith the longitudinal resistivity for both the compounds. The detailed analysis\nindicates that in anomalous Hall conductivity, the intrinsic Karplus-Luttinger\nBerry phase mechanism dominates over the extrinsic skew scattering and\nside-jump mechanism.",
        "positive": "A novel intrinsic interface state controlled by atomic stacking sequence\n  at interfaces of SiC/SiO$_2$: On the basis of ab-initio total-energy electronic-structure calculations, we\nfind that interface localized electron states at the SiC/SiO$_2$ interface\nemerge in the energy region between 0.3 eV below and 1.2 eV above the bulk\nconduction-band minimum (CBM) of SiC, being sensitive to the sequence of atomic\nbilayers in SiC near the interface. These new interface states unrecognized in\nthe past are due to the peculiar characteristics of the CBM states which are\ndistributed along the crystallographic channels. We also find that the electron\ndoping modifies the energetics among the different stacking structures.\nImplication for performance of electron devices fabricated on different SiC\nsurfaces are discussed."
    },
    {
        "anchor": "X-ray resonant magnetic scattering from structurally and magnetically\n  rough interfaces in multilayered systems II. Diffuse scattering: The theoretical formulation of x-ray resonant magnetic scattering from rough\nsurfaces and interfaces is given for the diffuse (off-specular) scattering, and\ngeneral expressions are derived in both the Born approximation (BA) and the\ndistorted-wave Born approximation (DWBA) for both single and multiple\ninterfaces. We also give in the BA the expression for off-specular magnetic\nscattering from magnetic domains. For this purpose, structural and magnetic\ninterfaces are defined in terms of roughness parameters related to their\nheight-height correlation functions and the correlations between them. The\nresults are generalized to the case of multiple interfaces, as in the case of\nthin films or multilayers. Theoretical calculations for each of the cases are\nillustrated as numerical examples and compared with experimental data of\nmangetic diffuse scattering from a Gd/Fe multilayer.",
        "positive": "Direct visualization of topological transitions and higher-order\n  topological states in photonic metasurfaces: Topological photonic systems represent a new class of optical materials\nsupporting boundary modes with unique properties, not found in conventional\nphotonics. While the early research on topological photonics has focused on\nedge and surface modes in 2D and 3D systems, respectively, recently\nhigher-order topological insulators (HOTIs) supporting lower-dimensional\nboundary states have been introduced. In this work we design and experimentally\nrealize a photonic kagome metasurface exhibiting a Wannier-type higher-order\ntopological phase. We demonstrate and visualize the emergence of a topological\ntransition and opening of a Dirac cone by directly exciting the bulk modes of\nthe HOTI metasurface via solid-state immersion spectroscopy. The open nature of\nthe metasurface is then utilized to directly image topological boundary states.\nWe show that, while the domain walls host 1D edge states, their bending induces\n0D higher-order topological modes confined to the corners. The demonstrated\nmetasurface hosting topological boundary modes of different dimensionality\npaves the way to a new generation of universal and resilient optical devices\nwhich can controllably scatter, trap and guide optical fields in a robust way."
    },
    {
        "anchor": "Slip avalanches in metallic glasses and granular matter reveal universal\n  dynamics: Universality in materials deformation is of intense interest: universal\nscaling relations if exist would bridge the gap from microscopic deformation to\nmacroscopic response in a single material-independent fashion. While recent\nagreement of the force statistics of deformed nanopillars, bulk metallic\nglasses, and granular materials with mean-field predictions supports the idea\nof universal scaling relations, here for the first time we demonstrate that the\nuniversality extends beyond the statistics, and applies to the slip dynamics as\nwell. By rigorous comparison of two very different systems, bulk metallic\nglasses and granular materials in terms of both the statistics and dynamics of\nforce fluctuations, we clearly establish a material-independent universal\nregime of deformation. We experimentally verify the predicted universal scaling\nfunction for the time evolution of individual avalanches, and show that both\nthe slip statistics and dynamics are universal, i.e. independent of the scale\nand details of the material structure and interactions. These results are\nimportant for transferring experimental results across scales and material\nstructures in a single theory of deformation.",
        "positive": "Fabricating Superconducting Interfaces between Artificially-Grown\n  LaAlO$_3$ and SrTiO$_3$ Thin Films: Realization of a fully metallic two-dimensional electron gas at the interface\nbetween artificially-grown LaAlO$_3$ and SrTiO$_3$ thin films has been an\nexciting challenge. Here we present for the first time the successful\nrealization of a superconducting 2DEG at interfaces between artificially-grown\nLaAlO$_3$ and SrTiO$_3$ thin films. Our results highlight the importance of two\nfactors-the growth temperature and the SrTiO$_3$ termination. We use local\nfriction force microscopy and transport measurements to determine that in\nnormal growth conditions the absence of a robust metallic state at low\ntemperature in the artificially-grown LaAlO$_3$/SrTiO$_3$ interface is due to\nthe nanoscale SrO segregation occurring on the SrTiO$_3$ film surface during\nthe growth and the associated defects in the SrTiO$_3$ film. By adopting an\nextremely high SrTiO$_3$ growth temperature, we demonstrate a way to realize\nmetallic, down to the lowest temperature, and superconducting 2DEG at\ninterfaces between LaAlO$_3$ layers and artificially-grown SrTiO$_3$ thin\nfilms. This study paves the way to the realization of functional\nLaAlO$_3$/SrTiO$_3$ superlattices and/or artificial LaAlO$_3$/SrTiO$_3$\ninterfaces on other substrates."
    },
    {
        "anchor": "Spin Waves in Disordered III-V Diluted Magnetic Semiconductors: We propose a new scheme for numerically computing collective-mode spectra for\nlarge-size systems, using a reformulation of the Random Phase Approximation. In\nthis study, we apply this method to investigate the spectrum and nature of the\nspin-waves of a (III,Mn)V Diluted Magnetic Semiconductor. We use an impurity\nband picture to describe the interaction of the charge carriers with the local\nMn spins. The spin-wave spectrum is shown to depend sensitively on the\npositional disorder of the Mn atoms inside the host semiconductor. Both\nlocalized and extended spin-wave modes are found. Unusual spin and charge\ntransport is implied.",
        "positive": "Engineering molecular aggregate spectra: We show that optical properties of linear molecular aggregates undergo\ndrastic changes when aggregates are deposited on a metal surface. The\ndipole-dipole interactions of monomers with their images can result in strong\n{re-structuring of both the exciton band and the absorption spectrum, depending\non the arrangement of the monomer transition dipoles with respect to the\nsurface."
    },
    {
        "anchor": "Local heat emission due to unidirectional spin-wave heat conveyer effect\n  observed by lock-in thermography: Lock-in thermography measurements were performed to reveal heat source\ndistribution induced by the unidirectional spin-wave heat conveyer effect\n(USHCE) of magnetostatic surface spin waves. When the magnetostatic surface\nspin waves are excited in an yttrium iron garnet slab, the lock-in thermography\nimages show spatially biased sharp and complicated heating patterns, indicating\nthe importance of edge spin-wave dynamics for USHCE. The accessibility to the\nlocal heat emission properties allows us to clarify a capability of remote\nheating realized by USHCE; it can transfer energy for heating even through a\nmacro-scale air gap between two magnetic materials owing to the long-range\ndipole-dipole coupling.",
        "positive": "Gamma irradiated nanostructured NiFe2O4: Effect of gamma-photon on\n  morphological, structural, optical and magnetic properties: The current manuscript highlights the preparation of NiFe2O4 nanoparticles by\nadopting sol-gel auto combustion route. The prime focus of this study is to\ninvestigate the impact of gamma irradiation on the microstructural,\nmorphological, functional, optical and magnetic characteristics. The resulted\nNiFe2O4 products have been characterized employing numerous instrumental\nequipments such as FESEM, XRD, UV visible spectroscopy, FTIR and PPMS for a\nvariety of gamma ray doses (0 kGy, 25 kGy and 100 kGy). FESEM micrographs\nillustrate the aggregation of ferrite nanoparticles in pristine NiFe2O4 product\nhaving an average particle size of 168 nm and the surface morphology is altered\nafter exposure to gamma-irradiation. XRD spectra have been analyzed employing\nRietveld method and the results of the XRD investigation reveal the desired\nphases (cubic spinel phases) of NiFe2O4 with observing other transitional\nphases. Several microstructural parameters such as bond length, bond angle,\nhopping length etc. have been determined from the analysis of Rietveld method.\nThis study reports that the gamma irradiations demonstrate a great influence on\noptical bandgap energy and it varies from 1.80 and 1.89 eV evaluated via K M\nfunction. FTIR measurement depicts a proof for the persistence of Ni-O and Fe-O\nstretching vibrations within the respective products and thus indicating the\nsuccessful development of NiFe2O4. The saturation magnetization (MS) of\npristine Ni ferrite product is noticed to be 28.08 emug-1. A considerable\nincrease in MS is observed in case of low gamma-dose (25 kGy) and a decrement\nnature is disclosed after the result of high dose of gamma irradiation\n(100kGy)."
    },
    {
        "anchor": "Effect of vanadium catalysts on hydrogen evolution from NaBH4: NaBH4 is a very cheap and hydrogen rich material and a potential hydrogen\nstore. However, high temperature of its thermal decomposition (above\n530{\\deg}C) renders it inapplicable in practical use. Here, we have studied the\neffect of addition of diverse V containing catalysts on thermal hydrogen\ndesorption. It turns out that mechanochemical doping of NaBH4 with vanadium\nmetal, its oxides or nanoparticles lowers the temperature of pyrolysis\nsignificantly. Notably, NaBH4 milled for 3 hrs with 25 wt.% of V2O5 or VO2\nreleases ca. 70 % of stored hydrogen in the temperature range from ca.\n370{\\deg}C to 450{\\deg}C. On the other hand, precursors and solvents used to\nprepare rather uniform vanadium nanoparticles (ca. 4nm) suspended in THF or\nless uniform and larger ones (ca. 28nm) in ortho difluorobenzene, have adverse\neffect on purity of hydrogen evolved.",
        "positive": "25-nm diamond crystals hosting single NV color centers sorted by\n  photon-correlation near-field microscopy: Diamond nanocrystals containing highly photoluminescent color centers are\nattractive non-classical and near-field light sources. For near-field\napplications the size of the nanocrystal is crucial since it defines the\noptical resolution. NV (Nitrogen-Vacancy) color centers are efficiently created\nby proton irradiation and annealing of a nanodiamond powder. Using near-field\nmicroscopy and photon statistics measurements, we show that nanodiamond with\nsize down to 25 nm can hold a single NV color center with bright and stable\nphotoluminescence."
    },
    {
        "anchor": "Superhyperfine interactions in Ce3+ doped LiYF4 crystal: ENDOR\n  measurements: The first observation of the resolved Mims electron-nuclear double resonance\n(ENDOR) spectra from the nearby and remote nuclei of 19F and 7Li nuclei on\nimpurity Ce3+ ions in LiYF4 crystal is reported. It shows that LiYF4:Ce3+\nsystem can be exploited as a convenient matrix for performing spin\nmanipulations and adjusting quantum computation protocols while ENDOR technique\ncould be used for the investigation of electron-nuclear interaction with all\nthe nuclei of the system and exploited for the electron-nuclear spin\nmanipulations.",
        "positive": "Precise effective masses from density functional perturbation theory: The knowledge of effective masses is a key ingredient to analyze numerous\nproperties of semiconductors, like carrier mobilities, (magneto-)transport\nproperties, or band extrema characteristics yielding carrier densities and\ndensity of states. Currently, these masses are usually calculated using\nfinite-difference estimation of density functional theory (DFT) electronic band\ncurvatures. However, finite differences require an additional convergence study\nand are prone to numerical noise. Moreover, the concept of effective mass\nbreaks down at degenerate band extrema. We assess the former limitation by\ndeveloping a method that allows to obtain the Hessian of DFT bands directly,\nusing density functional perturbation theory (DFPT). Then, we solve the latter\nissue by adapting the concept of `transport equivalent effective mass' to the\n$\\vec{k} \\cdot \\hat{\\vec{p}}$ framework. The numerical noise inherent to\nfinite-difference methods is thus eliminated, along with the associated\nconvergence study. The resulting method is therefore more general, more robust\nand simpler to use, which makes it especially appropriate for high-throughput\ncomputing. After validating the developed techniques, we apply them to the\nstudy of silicon, graphane, and arsenic. The formalism is implemented into the\nABINIT software and supports the norm-conserving pseudopotential approach, the\nprojector augmented-wave method, and the inclusion of spin-orbit coupling. The\nderived expressions also apply to the ultrasoft pseudopotential method."
    },
    {
        "anchor": "Light scattering from an isotropic layer between uniaxial crystals: We develop a model for the reflection and transmission of plane waves by an\nisotropic layer sandwiched between two uniaxial crystals of arbitrary\norientation. In the laboratory frame, reflection and transmission coefficients\ncorresponding to the principal polarization directions in each crystal are\ngiven explicitly in terms of the c-axis and propagation directions. The\nsolution is found by first deriving explicit expressions for reflection and\ntransmission amplitude coefficients for waves propagating from an arbitrarily\noriented uniaxial anisotropic material into an isotropic material. By combining\nthese results with Lekner's (1991) earlier treatment of waves propagating from\nisotropic media to anisotropic media and employing a matrix method we determine\na solution to the general form of the multiple reflection case. The example\nsystem of a wetted interface between two ice crystals is used to contextualize\nthe results.",
        "positive": "Benefits of Resource Strategy for Sustainable Materials Research and\n  Development: Material and product life cycles are based on complex value chains of\ntechnology-specific elements. Resource strategy aspects of essential and\nstrategic raw materials have a direct impact on applications of new\nfunctionalized materials or the development of novel products. Thus, an urgent\nchallenge of modern materials science is to obtain information about the supply\nrisk and environmental aspects of resource utilization, especially at an early\nstage of basic research. Combining the fields of materials science, industrial\nengineering and resource strategy enables a multidisciplinary research approach\nto identify specific risks within the value chain, aggregated as the so-called\nresource criticality. Here, we demonstrate a step-by-step criticality\nassessment in the sector of basic materials research for multifunctional\nhexagonal manganite YMnO3, which can be a candidate for future electronic\nsystems. Raw material restrictions can be quantitatively identified, even at\nsuch an early stage of materials research, from eleven long-term indicators\nincluding our new developed Sector Competition Index. This approach for\nresource strategy for modern material science integrates two objective targets:\nreduced supply risk and enhanced environmental sustainability of new\nfunctionalized materials, showing drawbacks but also benefits towards a\nsustainable materials research and development."
    },
    {
        "anchor": "Topological quantum materials from the viewpoint of chemistry: Topology, a mathematical concept, has recently become a popular and truly\ntransdisciplinary topic encompassing condensed matter physics, solid state\nchemistry, and materials science. Since there is a direct connection between\nreal space, namely atoms, valence electrons, bonds and orbitals, and reciprocal\nspace, namely bands and Fermi surfaces, via symmetry and topology, classifying\ntopological materials within a single-particle picture is possible. Currently,\nmost materials are classified as trivial insulators, semimetals and metals, or\nas topological insulators, Dirac and Weyl nodal-line semimetals, and\ntopological metals. The key ingredients for topology are: certain symmetries,\nthe inert pair effect of the outer electrons leading to inversion of the\nconduction and valence bands, and spin-orbit coupling. This review presents the\ntopological concepts related to solids from the viewpoint of a solid-state\nchemist, summarizes techniques for growing single crystals, and describes basic\nphysical property measurement techniques to characterize topological materials\nbeyond their structure and provide examples of such materials. Finally, a brief\noutlook on the impact of topology in other areas of chemistry is provided at\nthe end of the article.",
        "positive": "Thermodynamic and dynamic dielectric properties of one-dimensional\n  hydrogen bonded ferroelectric of PbHPO$_4$-type: Within the modified model of proton ordering of one-dimensional ferroelectric\nhaving hydrogen bonds of PbHPO$_4$-type, their thermodynamic and dynamic\ncharacteristics are studied and calculated taking into account the linear (by\ncrystal deformations $\\varepsilon_i$ ($i=1,3$) and $\\varepsilon_4$)\ncontributions into the energy of a proton system but without taking into\naccount the tunneling in the two-particle cluster approximation. There has been\nobtained a good quantitative description of the temperature dependence of\npolarization, static dielectric permittivity, heat capacity and frequency\ndependence of dynamic dielectric permittivity at different temperatures for\nPbHPO$_4$ and PbHDO$_4$ crystals."
    },
    {
        "anchor": "On the performance of interatomic potential models of iron: comparison\n  of the phase diagrams: In order to study the performance of interatomic potentials and their\nreliability at higher pressures, the phase diagram of four different\nembedded-atom type potential models of iron is compared. The calculations were\ndone by the nested sampling technique in the pressure range 0.1 GPa-100 GPa.\nThe low pressure stable structure is found to be the body- centred cubic in all\ncases, but the higher pressure phases show a great variation, being\nface-centred cubic, hexagonal close-packed and - at very low temperatures -\ndifferent body-centred tetragonal phases are observed as well. The melting line\nis overestimated considerably for three of the models, but for the one where\nliquid properties had been taken into account during the potential fitting\nprocess, the agreement with experimental results is good, even at very high\npressures.",
        "positive": "Interconnection of point defect parameters in solids with bulk\n  properties: A review: Two models have been proposed for the interconnection of the defect Gibbs\nenergy g^i with bulk properties almost 60 and 30 years ago, respectively. The\none, proposed by Zener, assumes that g^i can be accounted for the work that\ngoes into straining the lattice and hence it is proportional to the shear\nmodulus of the solid. The other, considers that, since g^i corresponds to an\nisobaric and isothermal process, it should be proportional to the isothermal\nbulk modulus and the mean volume per atom. The results of these two models are\ncompared for different processes (defect formation, self-diffusion activation,\nhetero-diffusion) in a variety of solids including metals (fcc, bcc and\ntetragonal) as well as solids that exhibit superionic behavior. We find that\nthe latter model does better than the former."
    },
    {
        "anchor": "Quantum Hall states observed in thin films of Dirac semimetal Cd3As2: A well known semiconductor Cd3As2 has reentered the spotlight due to its\nunique electronic structure and quantum transport phenomena as a topological\nDirac semimetal. For elucidating and controlling its topological quantum state,\nhigh-quality Cd3As2 thin films have been highly desired. Here we report the\ndevelopment of an elaborate growth technique of high-crystallinity and\nhigh-mobility Cd3As2 films with controlled thicknesses and the observation of\nquantum Hall effect dependent on the film thickness. With decreasing the film\nthickness to 10 nm, the quantum Hall states exhibit variations such as a change\nin the spin degeneracy reflecting the Dirac dispersion with a large Fermi\nvelocity. Details of the electronic structure including subband splitting and\ngap opening are identified from the quantum transport depending on the\nconfinement thickness, suggesting the presence of a two-dimensional topological\ninsulating phase. The demonstration of quantum Hall states in our high-quality\nCd3As2 films paves a road to study quantum transport and device application in\ntopological Dirac semimetal and its derivative phases.",
        "positive": "Gyrotropic impact upon negatively refracting surfaces: Surface wave propagation at the interface between different types of\ngyrotropic materials and an isotropic negatively refracting medium, in which\nthe relative permittivity and relative permeability are, simultaneously,\nnegative is investigated. A general approach is taken that embraces both\ngyroelectric and gyromagnetic materials, permitting the possibility of\noperating in either the low GHz, THz or the optical frequency regimes. The\nclassical transverse Voigt configuration is adopted and a complete analysis of\nnon-reciprocal surface wave dispersion is presented. The impact of the surface\npolariton modes upon the reflection of both plane waves and beams is discussed\nin terms of resonances and an example of the influence upon the Goos-Hanchen\nshift is given."
    },
    {
        "anchor": "Mechanisms for directed self-assembly of heteroepitaxial Ge/Si quantum\n  dots with deterministic placement and sub-23nm spacing on SiC nanotemplates: Artificially ordered Ge quantum dot (QD) arrays, where confined carriers can\ninteract via exchange coupling, may create unique functionalities such as\ncluster qubits and spintronic bandgap systems. Development of such arrays for\nquantum computing requires fine control over QD size and spatial arrangement on\nthe sub-35 nm length scale. We employ fine-probe electron-beam irradiation to\nlocally decompose ambient hydrocarbons onto a bare Si (001) surface. These\ncarbonaceous patterns are annealed in UHV, forming ordered arrays of nanoscale\nSiC precipitates that serve as templates for subsequent Ge quantum dot\nself-assembly during heteroepitaxy. This templating approach has so far\nproduced interdot spacings down to 22.5 nm, and smaller spacings should be\npossible. We investigate the templated feature evolution during UHV processing\nto identify key mechanisms that must be controlled in order to preserve pattern\nfidelity and reduce broadening of the quantum dot size distribution. A key\nfinding is that the presence of a small background of excess carbon reduces Ge\nsurface diffusion, thereby suppressing coarsening to relatively high\ntemperatures. In fact, coarsening of the carbonaceous nanodot template prior to\nconversion to SiC can be a more important contributor to size dispersion, and\nmust be avoided through control of thermal budget.",
        "positive": "Dielectric Properties of Conductively Loaded Polyimides in the Far\n  Infrared: The dielectric properties of selected conductively-loaded polyimide samples\nare characterized in microwave through far infrared wavebands. These materials,\nbelonging to the Vespel\\textsuperscript{\\textregistered} family, are more\nreadily formed by direct machining than their ceramic loaded epoxy counterparts\nand present an interesting solution for realizing absorptive optical control\nstructures. Measurements spanning a spectral range from 1 to 600\\,${\\rm\ncm^{-1}}$ (0.03 to 18\\,THz) were preformed and used in parametrization of the\nmedia's dielectric function at frequencies below $\\approx3\\,$THz."
    },
    {
        "anchor": "Magnetic Field scaling of Relaxation curves in Small Particle Systems: We study the effects of the magnetic field on the relaxation of the\nmagnetization of small monodomain non-interacting particles with random\norientations and distribution of anisotropy constants. Starting from a master\nequation, we build up an expression for the time dependence of the\nmagnetization which takes into account thermal activation only over barriers\nseparating energy minima, which, in our model, can be computed exactly from\nanalytical expressions. Numerical calculations of the relaxation curves for\ndifferent distribution widths, and under different magnetic fields H and\ntemperatures T, have been performed. We show how a $\\svar$ scaling of the\ncurves, at different T and for a given H, can be carried out after proper\nnormalization of the data to the equilibrium magnetization. The resulting\nmaster curves are shown to be closely related to what we call effective energy\nbarrier distributions, which, in our model, can be computed exactly from\nanalytical expressions. The concept of effective distribution serves us as a\nbasis for finding a scaling variable to scale relaxation curves at different H\nand a given T, thus showing that the field dependence of energy barriers can be\nalso extracted from relaxation measurements.",
        "positive": "Fermi Level Engineering and Mechanical Properties of High Entropy\n  Carbides: Fermi level engineering and mechanical properties evolution in high entropy\ncarbides are investigated by theoretical and experimental means. Massive\nelemental diversity in high entropy ceramics broadens the compositional space\nbut imposes great challenges in composition selection and property\ninvestigation. We have utilized the valence electron concentration (VEC)\ndescriptor to design and predict properties of high entropy carbides. The VEC\nregulates the Fermi energy and systematically alters the bonding\ncharacteristics of materials. As a result, mechanical properties evolve as\nfunction of the VEC. At VEC 8.4, the strong {\\sigma} bonding states stem from\nfilled overlapping metal d and carbon p orbitals, which results in maximum\nresistance to shear deformation and highest hardness. Beyond or below the\noptimum VEC point of 8.4, mechanical response degrades due to filling or\nemptying of energy orbitals that facilitates shear deformation. Furthermore,\nthe optimum VEC point can shift based on the constituent metals that formulate\nthe high entropy carbide. Our analyses demonstrate strong correlation between\ncalculated hardness and shear modulus. As an experimental complement, a set of\nhigh entropy carbides are synthesized, and mechanical properties investigated.\nThe measured hardness follows theoretical predictions and the highest hardness\nof ~30 GPa is achieved at VEC 8.4. In contrast, hardness decreases by 50% when\nVEC is 9.4. Designing high entropy carbides based on VEC and understanding\nmechanical properties at an electronic level enables one to manipulate the\ncomposition spectrum to procure a desired mechanical response from a chemically\ndisordered crystal."
    },
    {
        "anchor": "Gaussian Approximation Potential: an interatomic potential derived from\n  first principles Quantum Mechanics: Simulation of materials at the atomistic level is an important tool in\nstudying microscopic structure and processes. The atomic interactions necessary\nfor the simulation are correctly described by Quantum Mechanics. However, the\ncomputational resources required to solve the quantum mechanical equations\nlimits the use of Quantum Mechanics at most to a few hundreds of atoms and only\nto a small fraction of the available configurational space. This thesis\npresents the results of my research on the development of a new interatomic\npotential generation scheme, which we refer to as Gaussian Approximation\nPotentials. In our framework, the quantum mechanical potential energy surface\nis interpolated between a set of predetermined values at different points in\natomic configurational space by a non-linear, non-parametric regression method,\nthe Gaussian Process. To perform the fitting, we represent the atomic\nenvironments by the bispectrum, which is invariant to permutations of the atoms\nin the neighbourhood and to global rotations. The result is a general scheme,\nthat allows one to generate interatomic potentials based on arbitrary quantum\nmechanical data. We built a series of Gaussian Approximation Potentials using\ndata obtained from Density Functional Theory and tested the capabilities of the\nmethod. We showed that our models reproduce the quantum mechanical potential\nenergy surface remarkably well for the group IV semiconductors, iron and\ngallium nitride. Our potentials, while maintaining quantum mechanical accuracy,\nare several orders of magnitude faster than Quantum Mechanical methods.",
        "positive": "A Graphene-Carbon Nanotube Hybrid Material for Photovoltaic Applications: Large area graphene sheets grown by chemical vapor deposition can potentially\nbe employed as a transparent electrode in photovoltaics if their sheet\nresistance can be significantly lowered, without any loss in transparency.\nHere, we report the fabrication of a graphene-conducting-carbon-nanotube (CCNT)\nhybrid material with a sheet resistance considerably lower than neat graphene,\nand with the requisite small reduction in transparency. Graphene is deposited\non top of a a self-assembled CCNT monolayer which creates parallel conducting\npaths on the graphene surface. The hybrid thereby circumvents electron\nscattering due to defects in the graphene sheet, and reduces the sheet\nresistance by a factor of two. The resistance can be further reduced by\nchemically doping the hybrid. Moreover, the chemically doped hybrid is more\nstable than a standalone chemically doped graphene sheet, as the CCNT network\nenhances the dopant binding. In order to understand the results, we develop a\n2D resistance network model in which we couple the CCNT layer to the graphene\nsheet and demonstrate the model accounts quantitatively for the resistance\ndecrease. Our results show that a graphene-CCNT hybrid system has high\npotential for use as a transparent electrode with high transparency and low\nsheet resistance."
    },
    {
        "anchor": "Halogen adsorption and reaction with Bi$_2$(Se,Te)$_3$ and\n  Bi/Bi$_2$(Se,Te)$_3$: Bi$_2$Se$_3$ and Bi$_2$Te$_3$, and these same surfaces covered with Bi films,\nare exposed to Br$_2$ and Cl$_2$ in ultra-high vacuum. Low energy electron\ndiffraction (LEED) and low energy ion scattering (LEIS) are used to investigate\nthe surface composition before and after halogen exposure. It is found that\nBr$_2$ weakly chemisorbs to the Se- or Te-terminated clean surfaces and light\nannealing removes the adsorbates restoring the intact surfaces. In contrast,\nhalogens dissociatively adsorb onto surfaces covered with an additional bilayer\nof Bi, having a p-doping effect. Annealing these halogen-covered surfaces at\n130{\\deg}C causes Bi atoms to be chemically etched away and the surface reverts\nto a Se- or Te-termination. This work shows how halogen adsorption and reaction\ncan be used to modify the surface termination of such materials.",
        "positive": "DFT calculation for adatom adsorption on graphene sheet as a prototype\n  of carbon nano tube functionalization: DFT calculation of various atomic species on graphene sheet is investigated\nas prototypes for formation of nano-structures on carbon nanotube (CNT) wall.\nWe investigate computationally adsorption energies and adsorption sites on\ngraphene sheet for a lot of atomic species including transition metals, noble\nmetals, nitrogen and oxygen, using the DFT calculation as a prototype for CNT.\nThe suitable atomic species can be chosen as each application from those\nresults. The calculated results show us that Mo and Ru are bounded strongly on\ngraphene sheet with large diffusion barrier energy. On the other hand, some\natomic species has large binding energies with small diffusion barrier energies"
    },
    {
        "anchor": "Band gap evolution in Ruddlesden-Popper phases: We investigate the variation of the band gap across the Ruddlesden-Popper\n(RP) series (An+1BnX3n+1) in model chalcogenide, oxide, and halide materials to\nunderstand the factors influencing band gap evolution. In contrast to the\noxides and halides, we find the band gap of the chalcogenides evolve\ndifferently with the thickness of the perovskite blocks in these natural\nsuperlattices. We show that octahedral rotations (i.e. deviation of the B-X-B\nbond angles from 180) and quantum confinement effects compete to decide the\nband gap evolution of RP phases. The insights gained here will allow us to\nrationally design layered perovskite phases for electronics and\noptoelectronics.",
        "positive": "Study on the Formation of Nano tau 3 Phase by Mechanical Alloying: In the present investigation the pure elemental powder mixture of Al (70 at%)\nNi (15 at %), Cu (15 at %) was mechanically milled in an attritor ball mill for\n10, 20, 40, 60, 80 and 100 hours in hexane medium at 400 rpm. The isothermal\nannealing of 100 h mechanically milled powder has been done at 700 0C for 20,\n40 and 60 hours. The mechanically alloyed powders are characterized using X-ray\ndiffraction, differential thermal analysis and transmission electron microscopy\ntechniques. It was observed that mechanical alloying led to the formation of\nnano tau 3 phases in Al70 Cu15Ni15 after 80 h of milling. In the case of 100 h\nMM and subsequent annealing at 700 0 C for 20, 40 and 60 h, powder exhibited\nthe formation of tau 3 phases with bigger grain sizes. The phase formation and\ntransformations in the above systems have been discussed based."
    },
    {
        "anchor": "Spin-dependent Transparency of Ferromagnet/Superconductor Interfaces: Because the physical interpretation of the spin-polarization of a ferromagnet\ndetermined by point-contact Andreev reflection (PCAR) is non-trivial, we have\ncarried out parameter-free calculations of PCAR spectra based upon a\nscattering-theory formulation of Andreev reflection generalized to\nspin-polarized systems and a tight-binding linear muffin tin orbital method for\ncalculating the corresponding scattering matrices. PCAR is found to measure the\nspin-dependent interface transparency rather than the bulk polarization of the\nferromagnet which is strongly overestimated by free electron model fitting.",
        "positive": "Phase transitions and ferroelectrics: revival and the future in the\n  field: It appeared worthwhile to us to present a state-of-the-art look at the field\nof ferroelectrics. We are certainly not attempting to provide a complete review\nof all aspects of the field of ferroelectrics over the last years but we wish\nto transport a flavour of the current excitement in the field through the\n(subjective) choice of four specific examples of current interest: (i)\nPiezoelectrics and the morphotropic phase boundary, (ii) Multiferroics, (iii)\nThe effect of high pressure on ferroelectrics and (iv) Strain-engineering in\nferroelectric oxide thin films. For each topic we will try to work out both\ncurrent interesting approaches and an outlook into future challenges.\nThroughout our discussion, the reader is referred to a list of significant\nreview articles, books and papers in the field."
    },
    {
        "anchor": "Knot Architecture for Biocompatible and Semiconducting Two-Dimensional\n  Electronic Fibre Transistors: In recent years, the rising demand for close interaction with electronic\ndevices has led to a surge in the popularity of wearable gadgets. While\nwearable gadgets have generally been rigid due to their utilisation of\nsilicon-based technologies, flexible semiconducting fibre-based transistors\nwill be needed for future wearables as active sensing components or within\nmicroprocessors to manage and analyse data. Two-dimensional (2D) semiconducting\nflakes are yet to be investigated in fibre transistors but could offer a route\ntoward high-mobility, biocompatible and flexible fibre-based devices. Here we\nreport the electrochemical exfoliation of semiconducting two-dimensional (2D)\nflakes of tungsten diselenide (WSe2) and molybdenum disulfide (MoS2). The high\naspect ratio (>100) of the flakes achieves aligned and conformal flake-to-flake\njunctions on polyester fibres enabling transistors with mobilities ~ 1 cm^2\nV^-1 s^-1 and a current on/off ratio, Ion/Ioff ~ 10^2 - 10^4. Furthermore, the\ncytotoxic effects of the MoS2 and WSe2 flakes with human keratinocyte cells are\ninvestigated and found to be biocompatible. As an additional step, we create a\nunique transistor knot architecture by leveraging the fibre diameter to\nestablish the length of the transistor channel, facilitating a route to scale\ndown transistor channel dimensions (100 {\\mu}m) and utilise it to make MoS2\nfibre transistors with a human hair that achieves mobilities as high as {\\mu} ~\n15 cm^2 V^-1 s^-1.",
        "positive": "Ordering intermetallic alloys by ion irradiation: a way to tailor\n  magnetic media: Combining He ion irradiation and thermal mobility below 600K, we both trigger\nand control the transformation from chemical disorder to order in thin films of\nan intermetallic ferromagnet (FePd). Kinetic Monte Carlo simulations show how\nthe initial directional short range order determines order propagation.\nMagnetic ordering perpendicular to the film plane was achieved, promoting the\ninitially weak magnetic anisotropy to the highest values known for FePd films.\nThis post-growth treatment should find applications in ultrahigh density\nmagnetic recording."
    },
    {
        "anchor": "Characterization of a Disordered Above Room Temperature Skyrmion\n  Material Co8Zn8Mn4: Topologically non trivial spin textures host great promise for future\nspintronic applications. Skyrmions in particular are of burgeoning interest\nowing to their nanometric size, topological protection, and high mobility via\nultra-low current densities. It has been previously reported through magnetic\nsusceptibility, microscopy, and scattering techniques that\nCo$_{8}$Zn$_{8}$Mn$_{4}$ forms an above room temperature triangular skyrmion\nlattice. Here we report the synthesis procedure and characterization of a\npolycrystalline Co$_{8}$Zn$_{8}$Mn$_{4}$ bulk sample. We employ powder x-ray\ndiffraction, backscatter Laue diffraction, and neutron diffraction as\ncharacterization tools of the crystallinity of the samples, while magnetic\nsusceptibility and Small Angle Neutron Scattering (SANS) measurements are\nperformed to study the skyrmion phase. Magnetic susceptibility measurements\nshow a dip anomaly in the magnetization curves which persists over a range of\napproximately 305 K- 315 K. SANS measurements reveal a rotationally disordered\npolydomain skymrion lattice. Applying a recently developed symmetry-breaking\nmagnetic field sequence, we were able to orient and order the previously jammed\nstate to yield the prototypical hexagonal diffraction patterns, with secondary\ndiffraction rings.",
        "positive": "Electronic properties of topological insulator candidate CaAgAs: The topological phases of matter provide the opportunity to observe many\nexotic properties, like the existence of two dimensional topological surface\nstates in the form of Dirac cone in topological insulators, chiral transport\nthrough open Fermi arc in Weyl semimetals etc. However, these properties can\nonly affect the transport characteristics and therefore can be useful for\napplications only if the topological phenomena occur near the Fermi level.\nCaAgAs is a promising candidate, wherein the ab-initio calculations predict\nline-node at the Fermi level which on including spin-orbit coupling transforms\ninto a topological insulator. In this report, we study the electronic structure\nof CaAgAs with angle resolved photoemission spectroscopy (ARPES), ab-initio\ncalculations and transport measurements. The ARPES results show that the bulk\nvalence band crosses the Fermi energy at gamma-point and the band dispersion\nmatches the ab-initio calculations closely on shifting the Fermi energy by -0.5\neV. ARPES results are in good agreement with our transport measurements which\nshow abundant p-type carriers."
    },
    {
        "anchor": "Adsorption tuning of polarity and magnetism in AgCr2S4 monolayer: As a recent successfully exfoliated non van der Waals layered material,\nAgCrS2 has received a lot of attentions. Motivated by its structure related\nmagnetic and ferroelectric behavior, a theoretical study on its exfoliated\nmonolayer AgCr2S4 has been carried out in the present work. Based on density\nfunctional theory, the ground state and magnetic order of monolayer AgCr2S4\nhave been determined. The centrosymmetry emerges upon two-dimensional\nconfinement and thus eliminates the bulk polarity. Moreover, two-dimensional\nferromagnetism appears in the CrS2 layer of AgCr2S4 and can persist up to room\ntemperature. The surface adsorption has also been taken into consideration,\nwhich shows a nonmonotonic effect on the ionic conductivity through ion\ndisplacement of the interlayer Ag, but has little impact on the layered\nmagnetic structure.",
        "positive": "Stable and Efficient Linear Scaling First-Principles Molecular Dynamics\n  for 10,000+ atoms: The recent progress of linear-scaling or O(N) methods in the density\nfunctional theory (DFT) is remarkable. We expect that first-principles\nmolecular dynamics (FPMD) simulations based on DFT can now treat more realistic\nand complex systems using the O(N) technique. However, very few examples of\nO(N) FPMD simulations exist so far and the information for the accuracy or\nreliability of the simulations is very limited. In this paper, we show that\nefficient and robust O(N) FPMD simulations are now possible by the combination\nof the extended Lagrangian Born-Oppenheimer molecular dynamics method, which\nwas recently proposed by Niklasson et al (Phys. Rev. Lett. 100, 123004 (2008)),\nand the density matrix method as an O(N) technique. Using our linear-scaling\nDFT code Conquest, we investigate the reliable calculation conditions for the\naccurate O(N) FPMD and demonstrate that we are now able to do actual and\nreliable self-consistent FPMD simulation of a very large system containing\n32,768 atoms."
    },
    {
        "anchor": "Morphotropic interfaces in PMN-PT single crystals: The paper describes heterostructures spontaneously formed in PMN-PT single\ncrystals cooled under bias electric field applied along [001]pc and then\nzero-field-heated in the vicinity of the so-called depoling temperature. In\nparticular, formation of lamellar structures composed of tetragonal-like and\nrhombohedral-like layers extending over macroscopic (mm) lengths is\ndemonstrated by optical observations and polarized Raman investigations.",
        "positive": "Large linear magnetoresistance in a new Dirac material BaMnBi2: We report the synthesis of high quality single crystals of BaMnBi2 and\ninvestigate the transport properties of the samples. The Hall data reveals\nelectron-type carriers and a mobility mu(5K) =1500cm2/Vs. The temperature\ndependence of magnetization displays behavior that is different from CaMnBi2 or\nSrMnBi2 , which suggests the possible different magnetic structure of BaMnBi2.\nAngle-dependent magnetoresistance reveals the quasi-two-dimensional Fermi\nsurface. A crossover from semiclassical MR-H2 dependence in low field to MR-H\ndependence in high field is observed in transverse magnetoresistance. Our\nresults indicate the anisotropic Dirac fermion states in BaMnBi2."
    },
    {
        "anchor": "CHGNet: Pretrained universal neural network potential for\n  charge-informed atomistic modeling: The simulation of large-scale systems with complex electron interactions\nremains one of the greatest challenges for the atomistic modeling of materials.\nAlthough classical force fields often fail to describe the coupling between\nelectronic states and ionic rearrangements, the more accurate\n\\textit{ab-initio} molecular dynamics suffers from computational complexity\nthat prevents long-time and large-scale simulations, which are essential to\nstudy many technologically relevant phenomena, such as reactions, ion\nmigrations, phase transformations, and degradation.\n  In this work, we present the Crystal Hamiltonian Graph neural Network\n(CHGNet) as a novel machine-learning interatomic potential (MLIP), using a\ngraph-neural-network-based force field to model a universal potential energy\nsurface. CHGNet is pretrained on the energies, forces, stresses, and magnetic\nmoments from the Materials Project Trajectory Dataset, which consists of over\n10 years of density functional theory static and relaxation trajectories of\n$\\sim 1.5$ million inorganic structures. The explicit inclusion of magnetic\nmoments enables CHGNet to learn and accurately represent the orbital occupancy\nof electrons, enhancing its capability to describe both atomic and electronic\ndegrees of freedom. We demonstrate several applications of CHGNet in\nsolid-state materials, including charge-informed molecular dynamics in\nLi$_x$MnO$_2$, the finite temperature phase diagram for Li$_x$FePO$_4$ and Li\ndiffusion in garnet conductors. We critically analyze the significance of\nincluding charge information for capturing appropriate chemistry, and we\nprovide new insights into ionic systems with additional electronic degrees of\nfreedom that can not be observed by previous MLIPs.",
        "positive": "Optically Helicity-Dependent Orbital and Spin Dynamics in\n  Two-Dimensional Ferromagnets: Disentangling orbital (OAM) and spin (SAM) angular momenta in the ultrafast\nspin dynamics of two-dimensional (2D) ferromagnets on subfemtoseconds is a\nchallenge in the field of ultrafast magnetism. Herein, we employed\nnon-collinear spin version of real-time time-dependent density functional\ntheory to investigate the orbital and spin dynamics of 2D ferromagnets Fe3GeTe2\n(FGT) induced by circularly polarized light. Our results show the\ndemagnetization of Fe sublattice in FGT is accompanied by helicity-dependent\nprecession of OAM and SAM excited by circularly polarized lasers. We further\nidentify that precession of OAM and SAM in FGT is faster than the\ndemagnetization within a few femtoseconds. Remarkably, circularly polarized\nlasers can significantly induce a periodically transverse response of OAM and\nSAM on very ultrafast timescales of ~250 attoseconds. Our finding suggests a\npowerful new route for attosecond regimes of the angular momentum manipulation\nto coherently control helicity-dependent orbital and spin dynamics in 2D\nlimits."
    },
    {
        "anchor": "Intervalley quantum interference and measurement of Berry phase in\n  bilayer graphene: Chiral quasiparticles in Bernal-stacked bilayer graphene have\nvalley-contrasting Berry phases of 2{\\pi}. This nontrival topological\nstructure, associated with the pseudospin winding along a closed Fermi surface,\nis responsible for various novel electronic properties, such as anti-Klein\ntunneling, unconventional quantum Hall effect, and valley Hall effect1-6. Here\nwe show that the quantum interference due to intervalley scattering induced by\natomic defects/impurities provides further insights into the topological nature\nof the bilayer graphene. The scattered chiral quasiparticles between distinct\nvalleys with opposite chirality undergoes a rotation of pseudospin that results\nin the Friedel oscillation with wavefront dislocations. The number of\ndislocations reflects the information about pseudospin texture and hence can be\nused to measure the Berry phase7. As demonstrated both experimentally and\ntheoretically, the Friedel oscillation, depending on the atomic defect/impurity\nat different sublattices, can exhibit N = 4, 2, or 0 additional wavefronts,\ncharacterizing the 2{\\pi} Berry phase of the bilayer graphene. Our results not\nonly provide a comprehensive study of the intervalley quantum interference in\nbilayer graphene, but also shed lights on the pseudospin physics.",
        "positive": "Large-gap quantum spin Hall insulators in tin films: The search of large-gap quantum spin Hall (QSH) insulators and effective\napproaches to tune QSH states is important for both fundamental and practical\ninterests. Based on first-principles calculations we find two-dimensional tin\nfilms are QSH insulators with sizable bulk gaps of 0.3 eV, sufficiently large\nfor practical applications at room temperature. These QSH states can be\neffectively tuned by chemical functionalization and by external strain. The\nmechanism for the QSH effect in this system is band inversion at the \\Gamma\npoint, similar to the case of HgTe quantum well. With surface doping of\nmagnetic elements, the quantum anomalous Hall effect could also be realized."
    },
    {
        "anchor": "MOCVD growth mechanisms of ZnO nanorods: ZnO is a promising material for the fabrication of light emitting devices.\nOne approach to achieve this goal is to use ZnO nanorods because of their\nexpected high crystalline and optical quality. Catalyst free growth of nanorods\nby metalorganic chemical vapour deposition (MOCVD) was carried out on (0001)\nsapphire substrates. Arrays of well-aligned, vertical nanorods were obtained\nwith uniform lengths and diameters. A thin wetting layer in epitaxy with the\nsapphire substrate is formed first, followed by pyramids and nanorods. The\nnucleation of nanorods occurs either directly at the interface, or later on top\nof some of the pyramids, suggesting various nucleation mechanisms. It is shown\nthat crystal polarity plays a critical role in the growth mechanism with\nnanorods of Zn polarity and their surrounding pyramids with O polarity. A\ngrowth mechanism is proposed to explain that most threading dislocations lie in\nthe wetting layer, with only a few in the pyramids and none in the nanorods.",
        "positive": "Transport properties of KTaO$_3$ from first-principles: The transport properties of the perovskites KTaO$_3$ are calculated using\nfirst-principles methods. Our study is based on Boltzmann transport theory and\nthe relaxation time approximation, where the scattering rate is calculated\nusing an analytical model describing the interactions of electrons and\nlongitudinal optical phonons. We compute the room-temperature electron mobility\nand Seebeck coefficients of KTaO$_3$, and SrTiO$_3$ for comparison, for a range\nof electron concentrations. The comparison between the two materials provides\ninsight into the mechanisms that determine room-temperature electron mobility,\nsuch as the effect of band-width and spin-orbit splitting. The results,\ncombined with the efficiency of the computational scheme developed in this\nstudy, provide a path to investigate and discover materials with targeted\ntransport properties."
    },
    {
        "anchor": "Empirical tight-binding method for large-supercell simulations of\n  disordered semiconductor alloys: We analyze and present applications of a recently proposed empirical\ntight-binding scheme for investigating the effects of alloy disorder on various\nelectronic and optical properties of semiconductor alloys, such as the band gap\nvariation, the localization of charge carriers, and the optical transitions.\nThe results for a typical antimony-containing III-V alloy, GaAsSb, show that\nthe new scheme greatly improves the accuracy in reproducing the experimental\nalloy band gaps compared to other widely used schemes. The atomistic nature of\nthe empirical tight-binding approach paired with a reliable parameterization\nenables more detailed physical insights into the effects of disorder in alloyed\nmaterials.",
        "positive": "Optimal Energy Dissipation in Sliding Friction Simulations: Non-equilibrium molecular dynamics simulations, of crucial importance in\nsliding friction, are hampered by arbitrariness and uncertainties in the\nremoval of the frictionally generated Joule heat. Building upon general\npre-existing formulation, we implement a fully microscopic dissipation approach\nwhich, based on a parameter-free, non-Markovian, stochastic dynamics, absorbs\nJoule heat equivalently to a semi-infinite solid and harmonic substrate. As a\ntest case, we investigate the stick-slip friction of a slider over a\ntwo-dimensional Lennard-Jones solid, comparing our virtually exact frictional\nresults with approximate ones from commonly adopted dissipation schemes.\nRemarkably, the exact results can be closely reproduced by a standard Langevin\ndissipation scheme, once its parameters are determined according to a general\nand self-standing variational procedure."
    },
    {
        "anchor": "Diffusion in binary and pseudo-binary L12 indides, stannides, gallides\n  and aluminides of rare-earth elements as studied using perturbed angular\n  correlation of 111In/Cd: Diffusional jumps can produce fluctuating electric field gradients at nuclei\nof jumping atoms. Using perturbed angular correlation of gamma rays (PAC),\njumps of probe atoms cause nuclear quadrupole relaxation that can be fitted to\nobtain the mean jump frequency. An overview is given of the application of this\napproach to highly ordered intermetallic compounds having the L12 (Cu3Au)\ncrystal structure. New results are then presented for jump frequencies of\n111In/Cd probe atoms in pseudo-binary L12 compounds of the forms In3(La1-xPrx)\nand (In1-xSnx)3La. For the mixed rare-earth system, jump frequencies are found\nto scale with composition between jump frequencies of the end-member phases\nIn3La and In3Pr. However, for the mixed sp-element system, a large decrease in\njump frequency is observed as Sn atoms substitute for In-atoms. This difference\nin behavior appears to depend on whether atomic disorder is on the diffusion\nsublattice (In-Sn substitution), as opposed to a neighboring sublattice (La-Pr\nsubstitution), whether or not there is a difference in diffusion mechanism\nbetween end-member phases, and/or whether or not there is a valence difference\nbetween the mixing atoms. All three conditions apply for only (In1-xSnx)3La.",
        "positive": "Influence of point defects on magnetic vortex structures: We employed micro-Hall magnetometry and micromagnetic simulations to\ninvestigate magnetic vortex pinning at single point defects in individual\nsubmicron-sized permalloy disks. Small ferromagnetic particles containing\nartificial point defects can be fabricated by using an image reversal electron\nbeam lithography process. Corresponding micromagnetic calculations, modeling\nthe defects within the disks as holes, give reasonable agreement between\nexperimental and simulated pinning and depinning field values."
    },
    {
        "anchor": "Stochastic 3D microstructure modeling of twinned polycrystals for\n  investigating the mechanical behavior of $\u03b3$-TiAl intermetallics: A stochastic 3D microstructure model for polycrystals is introduced which\nincorporates two types of twin grains, namely neighboring and inclusion twins.\nThey mimic the presence of crystal twins in $\\gamma$-TiAl polycrystalline\nmicrostructures as observed by 3D imaging techniques. The polycrystal grain\nmorphology is modeled by means of Voronoi and -- more generally -- Laguerre\ntessellations. The crystallographic orientation of each grain is either sampled\nuniformly on the space of orientations or chosen to be in a twinning relation\nwith another grain. The model is used to quantitatively study relationships\nbetween morphology and mechanical properties of polycrystalline materials. For\nthis purpose, full-field Fourier-based computations are performed to\ninvestigate the combined effect of grain morphology and twinning on the overall\nelastic response. For $\\gamma$-TiAl polycrystallines, the presence of twins is\nassociated with a softer response compared to polycrystalline aggregates\nwithout twins. However, when comparing the influence on the elastic response, a\nstatistically different polycrystalline morphology has a much smaller effect\nthan the presence of twin grains. Notably, the bulk modulus is almost\ninsensitive to the grain morphology and exhibits much less sensitivity to the\npresence of twins compared to the shear modulus. The numerical results are\nconsistent with a two-scale homogenization estimate that utilizes laminate\nmaterials to model the interactions of twins.",
        "positive": "Effect of Pressure on Electrical and optical Properties of Metal Doped\n  TiO$_2$: A comparative study of the electrical and optical properties has been done on\n3d-doped TiO$_2$. Ti$_{1-x}$M$_x$O$_2$ (M= Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn)\npowder and its corresponding pellets, with doping concentration $x= 0.05$. The\nsamples were prepared using the solid-state route. Optical and electrical\nmeasurements have been performed for all prepared samples and interestingly, it\nis observed that due to external pressure (i.e. strain) both the properties\nchange significantly. A rigorous theoretical calculation has also been carried\nout to verify the experimental band gap obtained from optical absorption\nspectroscopy. In case of pellet sample band gap decreases as compared to the\npowder sample due to variation of pressure inside the structures. Role of\ndoping has also been investigated both in pellet and powder forms and we found\nthat the band gap decreases as the atomic number of dopants increases. A\ncross-over behavior is seen in pellet samples on doping with Ni, Cu and Zn\n(i.e. band gap increases with an increase in the atomic number of dopant).\nElectrical resistivity measurements have been carried out for both pellet and\npowder samples and it is found that in the case of strained samples the value\nof resistivity is smaller while in the case of strain-free samples it is quite\nlarge. We believe that the present study suggests a novel approach for tuning\nthe electrical and optical properties of semiconducting oxides either from\ndoping or from applied pressure (or strain)."
    },
    {
        "anchor": "Origin of the magnetoelectric coupling effect in\n  Pb(Zr0.2Ti0.8)O3/La0.8Sr0.2MnO3 multiferroic heterostructures: The electronic valence state of Mn in Pb(Zr0.2Ti0.8)O3/La0.8Sr0.2MnO3\nmultiferroic heterostructures is probed by near edge x-ray absorption\nspectroscopy as a function of the ferroelectric polarization. We observe a\ntemperature independent shift in the absorption edge of Mn associated with a\nchange in valency induced by charge carrier modulation in the La0.8Sr0.2MnO3,\ndemonstrating the electronic origin of the magnetoelectric effect.\nSpectroscopic, magnetic, and electric characterization shows that the large\nmagnetoelectric response originates from a modified interfacial spin\nconfiguration, opening a new pathway to the electronic control of spin in\ncomplex oxide materials.",
        "positive": "Experimental manifestations of the Nb^{4+}-O^{-} polaronic excitons in\n  KTa_{0.988}Nb_{0.012}O_{3}: The formation of the photo-polaronic excitons in ABO_{3} perovskite type\noxides has been detected experimentally by means of the photoinduced electron\nparamagnetic resonance studies of KTa_{0.998}Nb_{0.012}O_{3} crystals. The\ncorresponding microwave X-band spectrum at T < 10 K consists of a narrow,\nnearly isotropic signal located at g ~ 2 and a strongly anisotropic component.\nThe first signal, which has a rich structure due to hyperfine interactions with\nthe lattice nuclei, is attributed to the single trapped charge carriers: the\nelectrons and/or the holes. The anisotropic spectrum is caused by the axial\ncenters oriented along the C_{4} pseudo-cubic principal crystalline axes. The\nspectrum angular dependence can be described well by an axial center with S =\n1, g_{\\parallel) = 0.82, g_{\\perp} = 0.52 and D = 0.44 cm^{-1}. The anisotropic\nspectrum is attributed to the Nb^{4+}-O^{-} polaronic excitons. The temperature\ndependence of the anisotropic component is characterized by two activation\nenergies: the internal dynamics activation E_{a1} = 3.7\\pm0.5 meV, which makes\nthe EPR spectrum unobservable above 10 K, and the destruction energy E_{a2} =\n52\\pm4 meV. By comparing the anisotropic photo-EPR spectrum and the\nphotoinduced optical absorption temperature dependencies, we found that the\nNb^{4+}-O^{-} polaronic excitons also manifested themselves via the ~0.7 eV\nwide absorption band arising under UV light excitation in the weakly\nconcentrated KTaO_{3}:Nb crystals."
    },
    {
        "anchor": "Optical properties of SiC nanotubes: A systematic $\\textit{ab initio}$\n  study: The band structure and optical dielectric function $\\epsilon$ of\nsingle-walled zigzag\n[(3,0),(4,0),(5,0),(6,0),(8,0),(9,0),(12,0),(16,0),(20,0),(24,0)], armchair\n[(3,3),(4,4),(5,5),(8,8),(12,12),(15,15)], and chiral\n[(4,2),(6,2),(8,4),(10,4)] SiC-NTs as well as the single honeycomb SiC sheet\nhave been calculated within DFT with the LDA. It is found that all the SiC\nnanotubes are semiconductors, except the ultrasmall (3,0) and (4,0) zigzag\ntubes which are metallic. Furthermore, the band gap of the zigzag SiC-NTs which\nis direct, may be reduced from that of the SiC sheet to zero by reducing the\ndiameter ($D$), though the band gap for all the SiC nanotubes with a diameter\nlarger than ~20 \\AA$ $ is almost independent of diameter. For the electric\nfield parallel to the tube axis ($E\\parallel \\hat{z}$), the $\\epsilon''$ for\nall the SiC-NTs with a moderate diameter (say, $D$ $>$ 8 \\AA$ $) in the\nlow-energy region (0~6 eV) consists of a single distinct peak at ~3 eV.\nHowever, for the small diameter SiC nanotubes such as the (4,2),(4,4) SiC-NTs,\nthe $\\epsilon''$ spectrum does deviate markedly from this general behavior. In\nthe high-energy region (from 6 eV upwards), the $\\epsilon''$ for all the\nSiC-NTs exhibit a broad peak centered at ~7 eV. For the electric field\nperpendicular to the tube axis ($E\\perp \\hat{z}$), the $\\epsilon''$ spectrum of\nall the SiC-NTs except the (4,4), (3,0) and (4,0) nanotubes, in the low energy\nregion also consists of a pronounced peak at around 3 eV whilst in the\nhigh-energy region is roughly made up of a broad hump starting from 6 eV. The\nmagnitude of the peaks is in general about half of the magnitude of the\ncorresponding ones for $E\\parallel \\hat{z}$.",
        "positive": "Properties of single-layer graphene doped by nitrogen with different\n  concentrations: Graphene has vast promising applications on the nanoelectronics and\nspintronics because of its unique magnetic and electronic properties. Making\nuse of an ab initio spin-polarized density functional theory, implemented by\nthe method of Heyd-Scuseria-Ernzerhof 06(HSE06) hybrid functional, the\nproperties of nitrogen substitutional dopants in semi-metal monolayer graphene\nwere investigated. We found from our calculation, that introducing nitrogen\ndoping would possibly break energy degeneracy with respect to spin(spin\nsymmetry breaking) at some doping concentrations with proper dopant\nconfigurations. The spin symmetry breaking would cause spin-polarized effects,\nwhich induce magnetic response in graphene. This paper systematically analyzed\nthe dependence of magnetic moments and band gaps in graphene on doping\nconcentrations of nitrogen atoms, as well as dopant configurations."
    },
    {
        "anchor": "Scintillation Properties and Electronic Structure of Intrinsic and\n  Extrinsic Mixed Elpasolites Cs2NaRBr3I3 (R = La, Y): Scintillators attract wide research interest for their distinct applications\nin radiation detection. Elpasolite halides are among the most promising\nscintillators due to their high structural symmetry and good scintillation\nperformance. Better understanding of their underlying scintillation mechanism\nopens up new possibilities in scintillator development. In this work, we employ\na variety of experimental techniques to study the two mixed-anion elpasolites\nCs2NaRBr3I3 (R = La, Y). The emission of intrinsic Cs2NaRBr3I3 with a light\nyield ranging from 20,000 to 40,000 ph/MeV is dominant by self-trapped exciton\nemission. Partial substitution of R with Ce introduces a competing emission,\nthe Ce3+ 5d to 4f radiative transition. Ab initio calculations were performed\nto investigate the electronic structures as well as the binding energies of\npolarons in Cs2NaRBr6. The calculated large self-trapped exciton binding\nenergies are consistent with the observed high light yield due to self-trapped\nexciton emission. The unique electronic structure of halide elpasolites as\ncalculated enhances the STE stability and the STE emission. The highly tunable\nscintillation properties of mixed-anion elpasolites underscore the role of\ntheir complex scintillation mechanism. Our study provides guidance for the\ndesign of new elpasolites scintillators with exceptional energy resolution and\nlight yield desirable for applications.",
        "positive": "The gauge theory of dislocations: static solutions of screw and edge\n  dislocations: We investigate the T(3)-gauge theory of static dislocations in continuous\nsolids. We use the most general linear constitutive relations bilinear in the\nelastic distortion tensor and dislocation density tensor for the force and\npseudomoment stresses of an isotropic solid. The constitutive relations contain\nsix material parameters. In this theory both the force and pseudomoment\nstresses are asymmetric. The theory possesses four characteristic lengths l1,\nl2, l3 and l4 which are given explicitely. We first derive the\nthree-dimensional Green tensor of the master equation for the force stresses in\nthe translational gauge theory of dislocations. We then investigate the\nsituation of generalized plane strain (anti-plane strain and plane strain).\nUsing the stress function method, we find modified stress functions for screw\nand edge dislocations. The solution of the screw dislocation is given in terms\nof one independent length l1=l4. For the problem of an edge dislocation, only\ntwo characteristic lengths l2 and l3 arise with one of them being the same\nl2=l1 as for the screw dislocation. Thus, this theory possesses only two\nindependent lengths for generalized plane strain. If the two lengths l2 and l3\nof an edge dislocation are equal, we obtain an edge dislocation which is the\ngauge theoretical version of a modified Volterra edge dislocation. In the case\nof symmetric stresses we recover well known results obtained earlier."
    },
    {
        "anchor": "Synthesis and EOS study of orthorhombic (Fe,Ni)$_{7}$(C,Si)$_{3}$ and\n  its importance as a possible constituent of Earth's core: We have synthesized an orthorhombic phase of nickel and silicon doped\nFe$_{7}$C$_{3}$ at high-pressure and high temperature using a laser-heated\ndiamond anvil cell. The synthesized material is characterized using X-ray\ndiffraction (XRD), Raman spectroscopy, and Transmission Electron Microscopy\n(TEM) measurements. High-pressure XRD measurement at room temperature up to\naround 121 GPa is performed. The anomaly observed in the pressure evolution of\nunit cell volume around 79 GPa along with a slight elastic softening might be\nassociated with a magnetic transition present in the material. The estimated\nbulk modulus shows a higher value due to the presence of less compressible\nnickel in the material. Density at core condition is calculated from the\nthermal pressure corrected equation of state (EOS), which gives an excellent\nmatch with the PREM data.",
        "positive": "Theoretical investigation of the vertical dielectric screening\n  dependence on defects for few-layered van der Waals materials: First-principle calculations were employed to analyze the effects induced by\nvacancies of molybdenum (Mo) and sulfur (S) on the dielectric properties of\nfew-layered MoS2. We explored the combined effects of vacancies and dipole\ninteractions on the dielectric properties of few-layered MoS2. In the presence\nof dielectric screening, we investigated uniformly distributed Mo and S\nvacancies, and then considered the case of concentrated vacancies. Our results\nshow that the dielectric screening remarkably depends on the distribution of\nvacancies owing to the polarization induced by the vacancies and on the\ninterlayer distances. This conclusion was validated for a wide range of\nwide-gap semiconductors with different positions and distributions of\nvacancies, providing an effective and reliable method for calculating and\npredicting electrostatic screening of dimensionally reduced materials. We\nfurther provided a method for engineering the dielectric constant by changing\nthe interlayer distance, tuning the number of vacancies and the distribution of\nvacancies in few-layered van der Waals materials for their application in\nnanodevices and supercapacitors."
    },
    {
        "anchor": "Heat generation due to spin transport in spin valves: Using a macroscopic approach, we studied theoretically the heat generation\ndue to spin transport in a typical spin valve with nonmagnetic spacer layer of\nfinite thickness. Our analysis shows that the spin-dependent heat generation\ncan also be caused by another mechanism, the spin-conserving scattering in the\npresence of spin accumulation gradient, in addition to the well-known spin-flip\nscattering. The two mechanisms have equal contributions in semi-infinite\nlayers, such as the ferromagnetic layers of the spin valve. However, in the\nnonmagnetic layer of a thickness much smaller than its spin-diffusion length,\nthe spin-dependent heat generation is dominated by the spin-flip scattering in\nthe antiparallel configuration, and by the spin-conserving scattering in the\nparallel configuration. We also proved that the spin-dependent heat generation\ncannot be interpreted as the Joule heating of the spin-coupled interface\nresistance in each individual layer. An effective resistance is proposed as an\nalternative so that the heat generation can still be described simply by\napplying Joule's law to an equivalent circuit.",
        "positive": "Formation of amorphous carbon multi-walled nanotubes from random initial\n  configurations: Amorphous carbon nanotubes (a-CNT) with up to four walls and sizes ranging\nfrom 200 to 3200 atoms have been simulated, starting from initial random\nconfigurations and using the Gaussian Approximation Potential [Phys. Rev. B 95,\n094203 (2017)]. The important variables (like density, height, and diameter)\nrequired to successfully simulate a-CNTs, were predicted with a machine\nlearning random forest technique. The models were validated $\\textit{ex post\nfacto}$ using density functional codes. The a-CNT models ranged from 0.55 nm -\n2 nm wide with an average inter-wall spacing of 0.31 nm. The topological\ndefects in a-CNTs were discussed and new defect configurations were observed.\nThe electronic density of states and localization in these phases were\ndiscussed and delocalized electrons in the $\\pi$ subspace were identified as an\nimportant factor for inter-layer cohesion. Spatial projection of the electronic\nconductivity favors axial transport along connecting hexagons, while\nnon-hexagonal parts of the network either hinder or bifurcate the electronic\ntransport. A vibrational density of states was calculated and is potentially an\nexperimentally testable fingerprint of the material and the appearance of a\nlow-frequency radial breathing mode was discussed. The thermal conductivity at\n300 K was calculated using the Green-Kubo formula."
    },
    {
        "anchor": "$Ab$ $initio$ hydrogen dynamics and the morphology of voids in amorphous\n  silicon: This paper presents an $ab$ $initio$ study of hydrogen dynamics inside\nnanometer-size voids in $a$-Si within the framework of the density-functional\ntheory for a varying hydrogen load of 10 to 30 H atoms/void at the low and high\ntemperature of 400 K and 700 K, respectively. Using the local density\napproximation and its generalized-gradient counterpart, the dynamics of\nhydrogen atoms inside the voids are examined with an emphasis on the diffusion\nof H atoms/molecules, and the resulting nanostructural changes of the void\nsurfaces. The results from simulations suggest that the microstructure of the\nhydrogen distribution on the void surfaces and the morphology of the voids are\ncharacterized by the presence of a significant number of monohydride Si-H\nbonds, along with a few dihydride Si-H$_2$ configurations. The study also\nreveals that a considerable number of (about 10--45 at.%) total H atoms inside\nvoids can appear as H$_2$ molecules for a hydrogen load of 10--30 H atoms/void.\nThe approximate shape of the voids is addressed from a knowledge of the\npositions of the void-surface atoms using the convex-hull approximation and the\nGaussian broadening of the pseudo-atomic surfaces of Si and H atoms.",
        "positive": "Physical Origin and Generic Control of Magnonic Band Gaps of\n  Dipole-Exchange Spin Waves in Width-Modulated-Nanostrip Waveguides: We report, for the first time, on a novel planar structure of\nmagnonic-crystal waveguides, made of a single magnetic material, in which the\nallowed and forbidden bands of propagating dipole-exchange spin-waves can be\nmanipulated by the periodic modulation of different widths in thin-film\nnanostrips. The origin of the presence of several magnonic wide band gaps and\nthe crucial parameters for controlling those band gaps of the order of ~10 GHz\nare found by micromagnetic numerical and analytical calculations. This work can\noffer a route to the potential application to broad-band spin-wave filters in\nthe GHz frequency range."
    },
    {
        "anchor": "Thermal cycling induced evolution and colossal exchange bias in\n  MnPS3/Fe3GeTe2 van der Waals heterostructures: The exchange bias phenomenon, inherent in exchange-coupled ferromagnetic and\nantiferromagnetic systems, has intrigued researchers for decades. Van der Waals\nmaterials, with their layered structure, provide an optimal platform for\nprobing such physical phenomena. However, achieving a facile and effective\nmeans to manipulate exchange bias in pristine van der Waals heterostructures\nremains challenging. In this study, we investigate the origin of exchange bias\nin MnPS3/Fe3GeTe2 van der Waals heterostructures. Our work demonstrates a\nmethod to modulate unidirectional exchange anisotropy, achieving an\nunprecedented nearly 1000% variation through simple thermal cycling. Despite\nthe compensated interfacial spin configuration of MnPS3, magneto-transport\nmeasurements reveal a huge 170 mT exchange bias at 5 K, the largest observed in\npristine van der Waals antiferromagnet-ferromagnet interfaces. This substantial\nmagnitude of the exchange bias is linked to an anomalous weak ferromagnetic\nordering in MnPS3 below 40 K. On the other hand, the tunability of exchange\nbias during thermal cycling is ascribed to the modified arrangement of\ninterfacial atoms and changes in the vdW gap during field cooling. Our findings\nhighlight a robust and easily adjustable exchange bias in van der Waals\nantiferromagnetic/ferromagnetic heterostructures, presenting a straightforward\napproach to enhance other interface related spintronic phenomena for practical\napplications.",
        "positive": "Polymer Nanocomposites: synthesis and characterization: This chapter deals with the fundamental properties of polymer nanocomposites\n(PNC) and their characteristics that play a significant role in deciding their\ncapability for the advanced energy storage device. The various synthesization\nmethods used for the preparation of the polymer electrolytes are described\nfollowed by the characterization techniques used for the analysis. The\nproperties of the polymer host, salt, nanofiller, ionic liquid, plasticizer and\nnanoclay/nanorod/nanowire are described. Various ion transport mechanism with\ndifferent nanoparticle dispersion in polymer electrolytes are highlighted. The\nvarious important results are summarized and a pathway is built to fulfill the\ndream of the future renewable source of energy that is economical and\nenvironmental benign. Chapter motivation is focused on the investigation of the\nrole of polymer host, aspect ratio, surface area, nanoparticle shape and size\nin terms of boosting the electrolytic/electrochemical properties of PNC. It\nwill certainly help in order to open new doors toward the development of the\nadvanced polymeric materials with overall balancing property for enhancement of\nthe fast solid state ionic conductor which would be revolutionized the energy\nstorage/conversion device technology."
    },
    {
        "anchor": "Anomalies in non-stoichiometric uranium dioxide induced by pseudo-phase\n  transition of point defects: A uniform distribution of point defects in an otherwise perfect\ncrystallographic structure usually describes a unique pseudo phase of that\nstate of a non-stoichiometric material. With off-stoichiometric uranium dioxide\nas a prototype, we show that analogous to a conventional phase transition,\nthese pseudo phases also will transform from one state into another via\nchanging the predominant defect species when external conditions of pressure,\ntemperature, or chemical composition are varied. This exotic transition is\nnumerically observed along shock Hugoniots and isothermal compression curves in\nUO2 with first-principles calculations. At low temperatures, it leads to\nanomalies (or quasi-discontinuities) in thermodynamic properties and electronic\nstructures. In particular, the anomaly is pronounced in both shock temperature\nand the specific heat at constant pressure. With increasing of the temperature,\nhowever, it transforms gradually to a smooth cross-over, and becomes less\ndiscernible. The underlying physical mechanism and characteristics of this type\nof transition are encoded in the Gibbs free energy, and are elucidated clearly\nby analyzing the correlation with the variation of defect populations as a\nfunction of pressure and temperature. The opportunities and challenges for a\npossible experimental observation of this phase change are also discussed.",
        "positive": "Simulations of Nanocrystalline Iron Formation under High Shear Strain: High-shear methods have long been used in experiments to refine grain\nstructures in metals, yet the underlying mechanisms remain elusive. We\ndemonstrate a refinement process using molecular dynamic simulations, wherein\nnanocrystalline structures are generated from initially perfect lattices under\nhigh-shear strain. The simulation cells undergo a highly disordered state,\nfollowed by recrystallization and grain coarsening, resulting in nanograins. We\nexplore the dependence on parameters such as temperature, heat dissipation\nrate, shear strain rate, and carbon impurity concentration. Higher temperatures\nlead to the formation of larger and longer grains. The faster heat dissipation\nsample initially yields more small grains, but their number subsequently\nreduces, and is lower than the slower heat dissipation sample at approximately\n1.5 strain. Slower strain rates do not promote nanograin formation. The\npresence of carbon impurities appears to have little effect on grain formation.\nThis detailed analysis affords insight into the mechanisms that control the\nformation of nanograins under high-shear conditions."
    },
    {
        "anchor": "Spin state and phase competition in TbBaCo_{2}O_{5.5} and the lanthanide\n  series LnBaCo_{2}O_{5+\u03b4} (0<=\u03b4<=1): A clear physics picture of TbBaCo$_{2}$O$_{5.5}$ is revealed on the basis of\ndensity functional theory calculations. An antiferromagnetic (AFM)\nsuperexchange coupling between the almost high-spin Co$^{3+}$ ions competes\nwith a ferromagnetic (FM) interaction mediated by both p-d exchange and double\nexchange, being responsible for the observed AFM-FM transition. And the\nmetal-insulator transition is accompanied by an xy/xz orbital-ordering\ntransition. Moreover, this picture can be generalized to the whole lanthanide\nseries, and it is predicted that a few room-temperature magnetoresistance\nmaterials could be found in LnBa$_{1-x}$A$_{x}$Co$_{2}$O$_{5+\\delta}$\n(Ln=Ho,Er,Tm,Yb,Lu; A=Sr,Ca,Mg).",
        "positive": "Nanofriction mechanisms derived from the dependence of friction on load\n  and sliding velocity from air to UHV on hydrophilic silicon: This paper examines friction as a function of the sliding velocity and\napplied normal load from air to UHV in a scanning force microscope (SFM)\nexperiment in which a sharp silicon tip slides against a flat Si(100) sample.\nUnder ambient conditions, both surfaces are covered by a native oxide, which is\nhydrophilic. During pump-down in the vacuum chamber housing the SFM, the\nbehavior of friction as a function of the applied normal load and the sliding\nvelocity undergoes a change. By analyzing these changes it is possible to\nidentify three distinct friction regimes with corresponding contact properties:\n(a) friction dominated by the additional normal forces induced by capillarity\ndue to the presence of thick water films, (b) higher drag force from ordering\neffects present in thin water layers and (c) low friction due to direct\nsolid-solid contact for the sample with the counterbody. Depending on\nenvironmental conditions and the applied normal load, all three mechanisms may\nbe present at one time. Their individual contributions can be identified by\ninvestigating the dependence of friction on the applied normal load as well as\non the sliding velocity in different pressure regimes, thus providing\ninformation about nanoscale friction mechanisms."
    },
    {
        "anchor": "Anisotropic intrinsic lattice thermal conductivity of phosphorene from\n  first principles: Phosphorene, the single layer counterpart of black phosphorus, is a novel\ntwo-dimensional semiconductor with high carrier mobility and a large\nfundamental direct band gap, which has attracted tremendous interest recently.\nIts potential applications in nano-electronics and thermoelectrics call for a\nfundamental study of the phonon transport. Here, we calculate the intrinsic\nlattice thermal conductivity of phosphorene by solving the phonon Boltzmann\ntransport equation (BTE) based on first-principles calculations. The thermal\nconductivity of phosphorene at $300\\,\\mathrm{K}$ is\n$30.15\\,\\mathrm{Wm^{-1}K^{-1}}$ (zigzag) and $13.65\\,\\mathrm{Wm^{-1}K^{-1}}$\n(armchair), showing an obvious anisotropy along different directions. The\ncalculated thermal conductivity fits perfectly to the inverse relation with\ntemperature when the temperature is higher than Debye temperature ($\\Theta_D =\n278.66\\,\\mathrm{K}$). In comparison to graphene, the minor contribution around\n$5\\%$ of the ZA mode is responsible for the low thermal conductivity of\nphosphorene. In addition, the representative mean free path (MFP), a critical\nsize for phonon transport, is also obtained.",
        "positive": "Fatigue crack growth in anisotropic aluminium sheets -- phase-field\n  modelling and experimental validation: Fatigue crack growth is decisive for the design of thin-walled structures\nsuch as fuselage shells of air planes. The cold rolling process, used to\nproduce the aluminium sheets this structure is made of, leads to anisotropic\nmechanical properties. In this contribution, we simulate the fatigue crack\ngrowth with a phase-field model due to its superior ability to model arbitrary\ncrack paths. A fatigue variable based on the Local Strain Approach describes\nthe progressive weakening of the crack resistance. Anisotropy regarding the\nfracture toughness is included through a structural tensor in the crack surface\ndensity. The model is parameterised for an aluminium AA2024-T351 sheet\nmaterial. Validation with a set of experiments shows that the fitted model can\nreproduce key characteristics of a growing fatigue crack, including crack path\ndirection and growth rate, considering the rolling direction."
    },
    {
        "anchor": "Coulomb effects in dynamics of polar lattices: Zone-center phonon frequencies of polar lattices are calculated for uniaxial\ncrystals from the symmetry arguments. Long-range Coulomb forces and crystal\nanisotropy are explicitly taken into account. Free-carrier contributions into a\ndielectric constant are included. The angular dispersion of optical-phonon\nmodes is compared with data for hexagonal 6H-SiC politype.",
        "positive": "Formation of nano-size Cr layers on LiNbO$_3$ crystal surfaces by\n  dissimilar electric charges: Morphology of metal thin layers deposited on polished surfaces of LiNbO$_3$\ncrystal with dissimilar electric charges has been studied using various methods\nof vacuum evaporation. The principal goal of the work is to optimizemethods of\nthin metal coating deposition applied to polar surfaces of LiNbO$_3$ crystal.\nThe conducted research has demonstrated that Cr deposition on LiNbO$_3$ crystal\nfaces is characterized by dissimilar polarity results in growth difference\nconditions of Cr films. The principal role here is played by the sign of the\nelectric charge on the crystal surface along with the type (thermal or\nmagnetron) and conditions observed during sputtering (deposition rate,\nsubstrate temperature etc)."
    },
    {
        "anchor": "Indirect K-edge bimagnon resonant inelastic X-ray scattering spectrum of\n  $\u03b1$-FeTe: We calculate the K-edge indirect bimagnon resonant inelastic X-ray scattering\n(RIXS) intensity spectra of the bicollinear antiferromagnetic order known to\noccur in the $\\alpha$-FeTe chalcogenide system. Utilizing linear spin wave\ntheory for this large-S spin system we find that the bimagnon spectrum contains\nfour scattering channels (two intraband and two interband). We find from our\ncalculations that for suitable energy-momentum combination the RIXS spectra can\nexhibit a one-, two- or three- peak structure. The number of peaks provides a\nclue on the various bimagnon excitation processes that can be supported both in\nand within the acoustic and optical magnon branches of the bicollinear\nantiferromagnet. Unlike the RIXS response of the antiferromagnetic or the\ncollinear antiferromagnetic spin ordering, the RIXS intensity spectrum of the\nbicollinear antiferromagnet does not vanish at the magnetic ordering wave\nvector $(\\pi/2,-\\pi/2)$. It is also sensitive to next-next nearest neighbor and\nbiquadratic coupling interactions. Our predicted RIXS spectrum can be utilized\nto understand the role of multi-channel bimagnon spin excitations present in\nthe $\\alpha$-FeTe chalcogenide.",
        "positive": "Tunable band-gap and isotropic light absorption from bismuth-containing\n  GaAs core$-$shell and multi$-$shell nanowires: Semiconductor core$-$shell nanowires based on the GaAs substrate are building\nblocks of many photonic, photovoltaic and electronic devices, thanks to the\nassociated direct band-gap and the highly tunable optoelectronic properties.\nThe selection of a suitable material system is crucial for custom designed\nnanowires tailored for optimised device performance. The bismuth containing\nGaAs materials are an imminent class of semiconductors which not only enable an\nexquisite control over the alloy strain and electronic structure but also offer\nthe possibility to suppress internal loss mechanisms in photonic devices.\nWhilst the experimental efforts to incorporate GaBiAs alloys in the nanowire\nactive region are still in primitive stage, the theoretical understanding of\nthe optoelectronic properties of such nanowires is only rudimentary. This work\nelucidates and quantifies the role of nanowire physical attributes such as its\ngeometry parameters and bismuth incorporation in designing light absorption\nwavelength and polarisation response. Based on multi-million atom tight-binding\nsimulations of the GaBiAs/GaAs core$-$shell and GaAs/GaBiAs/GaAs multi$-$shell\nnanowires, our results predict a large tuning of the absorption wavelength,\nranging from 0.9 $\\mu$m to 1.6 $\\mu$m, which can be controlled by engineering\neither Bi composition or nanowire diameter. The analysis of the strain profiles\nindicates a tensile character leading to significant light-hole mixing in the\nvalence band states. This offers a possibility to achieve\npolarisation-insensitive light interaction, which is desirable for several\nphotonic devices involving amplification and modulation of light. Furthermore,\nat low Bi compositions, the carrier confinement is quasi type-II, which further\nbroadens the suitability of these nanowires for myriad applications demanding\nlarge carrier separations..."
    },
    {
        "anchor": "Vacancy-induced enhancement of thermal conductivity in graphene: It is shown that the experimentally observed increase of the Young's modulus\nin single-layer graphene with low density of point defects leads to a\nnoticeably enhancement of the thermal conductivity in a wide temperature range\ndue to increasing the longitudinal and transverse phonon velocities.",
        "positive": "Complex refractive index variation in proton-damaged diamond: An accurate control of the optical properties of single crystal diamond\nduring microfabrication processes such as ion implantation plays a crucial role\nin the engineering of integrated photonic devices. In this work we present a\nsystematic study of the variation of both real and imaginary parts of the\nrefractive index of single crystal diamond, when damaged with 2 and 3 MeV\nprotons at low-medium fluences (range: 10^15 - 10^17 cm^-2). After implanting\nin 125x125 um^2 areas with a scanning ion microbeam, the variation of optical\npathlength of the implanted regions was measured with laser interferometric\nmicroscopy, while their optical transmission was studied using a spectrometric\nset-up with micrometric spatial resolution. On the basis of a model taking into\naccount the strongly non-uniform damage profile in the bulk sample, the\nvariation of the complex refractive index as a function of damage density was\nevaluated."
    },
    {
        "anchor": "2D Nb-doped MoS$_2$: Tuning the Exciton Transitions and Application to\n  p-type FETs: Two-dimensional (2D) MoS$_2$ has been intensively investigated for its use in\nthe fields of microelectronics, nanoelectronics, and optoelectronics. However,\nintrinsic 2D MoS$_2$ is usually used as the n-type semiconductor due to the\nunintentional sulphur vacancies and surface gas adsorption.The synthesis and\ncharacterization of 2D MoS$_2$ semiconductor of p-type are crucial for the\ndevelopment of relevant p-n junction devices, as well as the practical\napplications of 2D MoS$_2$ in the next-generation CMOS integrated circuit.\nHere, we synthesize high-quality, wafer-scale, 2D p-type MoS$_2$\n(Mo$_{1-x}$Nb$_x$S$_2$) with various niobium (Nb) mole fractions from 0 to 7.6%\nby a creative two-step method. The dielectric functions of 2D Mo1-xNbxS2 are\naccurately determined by spectroscopic ellipsometry. We find that the\nincreasing fraction of Nb dopant in 2D MoS$_2$ can modulate and promote the\ncombination of A and B exciton peaks of 2D MoS$_2$. The direct causes of this\nimpurity-tunable combination are interpreted as the joint influence of\ndecreasing peak A and broadening peak B. We explain the broadening peak B as\nthe multiple transitions from the impurity-induced valance bands to the\nconductive band minimum at K point of Brillouin zone by comparing and analyzing\nthe simulated electronic structure of intrinsic and 2D Nb-doped MoS$_2$. A\np-type FET based on the 2D Nb-doped MoS$_2$ was fabricated for\ncharacterization, and its working performance is expected to be adjustable as a\nfunction of concentration of Nb dopant according to our theoretical research.\nOur study is informative for comprehending optical and electronic properties of\nextrinsic 2D transitional metal dichalcogenides, which is important and\nimperative for the development and optimization of corresponding photonics and\noptoelectronics devices.",
        "positive": "Ternary inorganic compounds containing carbon, nitrogen, and oxygen at\n  high pressures: Ternary C_{x}N_{y}O_{z} compounds are actively researched as novel high\nenergy density and ultrahard materials. Although some synthesis work has been\nperformed at ambient conditions, very little is known about the high pressure\nchemistry of of C_{x}N_{y}O_{z} compounds. In this work, first principles\nvariable-composition evolutionary structure prediction calculations are\nperformed with the goal of discovering novel mixed C_{x}N_{y}O_{z} materials at\nambient and high pressure conditions. By systematically searching ternary\nvariable composition crystalline materials, the full ternary phase diagram is\nconstructed in the range of pressures from 0 to 100 GPa. The search finds the\nC_{2}N_{2}O crystal containing extended covalent network of C, N, and O atoms,\nhaving space group symmetry Cmc2_{1}, and stable above just 10 GPa. Several\nother novel metastable (CO)_{x}-(N)_{y} crystalline compounds discovered during\nthe search, including two polymorphs of C_{2}NO_{2} and two polymorphs of\nC_{3}N_{2}O_{3} crystals are found to be energetically favorable compared to\npolymeric carbon monoxide (CO) and nitrogen. Predicted new compounds are\ncharacterized by their Raman spectra and equations of state."
    },
    {
        "anchor": "Efficiency of Cathodoluminescence Emission by Nitrogen-Vacancy Color\n  Centers in Nanodiamond: Correlated electron microscopy and cathodoluminescence (CL) imaging using\nfunctionalized nanoparticles is a promising nanoscale probe of biological\nstructure and function. Nanodiamonds (NDs) that contain CL-emitting color\ncenters are particularly well suited for such applications. The intensity of CL\nemission from NDs is determined by a combination of factors, including:\nparticle size; density of color centers; efficiency of energy deposition by\nelectrons passing through the particle; and conversion efficiency from\ndeposited energy to CL emission. We report experiments and numerical\nsimulations that investigate the relative importance of each of these factors\nin determining CL emission intensity from NDs containing nitrogen-vacancy (NV)\ncolor centers. In particular, we find that CL can be detected from NV-doped NDs\nwith dimensions as small as ~ 40 nm, although CL emission decreases\nsignificantly for smaller NDs.",
        "positive": "Effect of uniaxial stress on the electronic band structure of NbP: The Weyl semimetal NbP exhibits a very small Fermi surface consisting of two\nelectron and two hole pockets, whose fourfold degeneracy in $k$ space is tied\nto the rotational symmetry of the underlying tetragonal crystal lattice. By\napplying uniaxial stress, the crystal symmetry can be reduced, which\nsuccessively leads to a degeneracy lifting of the Fermi-surface pockets. This\nis reflected by a splitting of the Shubnikov-de Haas frequencies when the\nmagnetic field is aligned along the $c$ axis of the tetragonal lattice. In this\nstudy, we present the measurement of Shubnikov-de Haas oscillations of\nsingle-crystalline NbP samples under uniaxial tension, combined with\nstate-of-the-art calculations of the electronic band structure. Our results\nshow qualitative agreement between calculated and experimentally determined\nShubnikov-de Haas frequencies, demonstrating the robustness of the\nband-structure calculations upon introducing strain. Furthermore, we predict a\nsignificant shift of the Weyl points with increasing uniaxial tension, allowing\nfor an effective tuning to the Fermi level at only 0.8% of strain along the $a$\naxis."
    },
    {
        "anchor": "First-Principles Electron-Phonon Interactions and Polarons in the Parent\n  Cuprate La$_2$CuO$_4$: Understanding electronic interactions in high-temperature superconductors is\nan outstanding challenge. In the widely studied cuprate materials, experimental\nevidence points to strong electron-phonon ($e$-ph) coupling and broad\nphotoemission spectra. Yet, the microscopic origin of this behavior is not\nfully understood. Here we study $e$-ph interactions and polarons in a\nprototypical parent (undoped) cuprate, La$_2$CuO$_4$ (LCO), by means of\nfirst-principles calculations. Leveraging parameter-free Hubbard-corrected\ndensity functional theory, we obtain a ground state with band gap and Cu\nmagnetic moment in nearly exact agreement with experiments. This enables a\nquantitative characterization of $e$-ph interactions. Our calculations reveal\ntwo classes of longitudinal optical (LO) phonons with strong $e$-ph coupling to\nhole states. These modes consist of Cu-O plane bond-stretching and bond-bending\nas well as vibrations of apical O atoms. The hole spectral functions, obtained\nwith a cumulant method that can capture strong $e$-ph coupling, exhibit broad\nquasiparticle peaks with a small spectral weight ($Z\\approx0.25$) and\npronounced LO-phonon sidebands characteristic of polaron effects. Our\ncalculations predict features observed in photoemission spectra, including a\n40-meV peak in the $e$-ph coupling distribution function not explained by\nexisting models. These results show that the universal strong $e$-ph coupling\nfound experimentally in lanthanum cuprates is an intrinsic feature of the\nparent compound, and elucidates its microscopic origin.",
        "positive": "Temperature dependent infrared spectroscopy of the Rashba spin-splitting\n  semiconductor BiTeI: We performed temperature dependent infrared spectroscopy measurements on\nBiTeI single crystals, which exhibit large Rashba spin-splitting. Similar to a\nprevious optical study, we found electronic excitations in good agreement with\nspin-split electronic bands. In addition, we report a low energy intraband\ntransition with an onset energy of about 40 meV and an unexpectedly large\nnumber of vibrational modes in the far-infrared spectral region. At least some\nof the modes have asymmetric Fano line-shape. These new observations cannot be\nexplained considering only the bulk band structure or crystal symmetry of\nBiTeI, and we proposed that the optical response is also affected by the\nsurface topology."
    },
    {
        "anchor": "Fundamental gaps of finite systems from the eigenvalues of a generalized\n  Kohn-Sham method: We present a broadly-applicable, physically-motivated first-principles\napproach to determining the fundamental gap of finite systems. The approach is\nbased on using a range-separated hybrid functional within the generalized\nKohn-Sham approach to density functional theory. Its key element is the choice\nof a range-separation parameter such that Koopmans' theorem for both the\nneutral and anionic is obeyed as closely as possible. We demonstrate the\nvalidity, accuracy, and advantages of this approach on first, second, and third\nrow atoms, the oligoacene family of molecules, and a set of hydrogen-passivated\nsilicon nanocrystals. This extends the quantitative usage of density functional\ntheory to an area long believed to be outside its reach.",
        "positive": "Effect of the lattice misfit on the equilibrium shape of strained\n  islands in Volmer-Weber growth: We have studied the effect of the misfit on the equilibrium shape of\nthree-dimensional pyramidal islands grown on a foreign substrate in the case of\nincomplete wetting (Volmer-Weber mode of growth). We have found that tensile\nislands have smaller aspect ratios compared with compressed islands owing to\nits better adhesion to the substrate. The average strains of consecutive layers\ndecrease faster with thickness in compressed than in tensile islands. The\nstrains decrease rapidly with thickness, with the consequence that above a\ncertain height, the upper layers of the pyramid become practically unstrained\nand does not contribute to a further reduction in the upper base. As a result,\nthe truncated pyramids are not expected to transform into full pyramids. Our\nresults are in good agreement with experimental observations in different\nsystems."
    },
    {
        "anchor": "Terahertz-Field-Induced Ferroelectricity in Quantum Paraelectric\n  SrTiO$_3$: \"Hidden phases\" are metastable collective states of matter that are typically\nnot accessible on equilibrium phase diagrams. These phases can host exotic\nproperties in otherwise conventional materials and hence may enable novel\nfunctionality and applications, but their discovery and access are still in\nearly stages. Using intense terahertz electric field excitation, we show that\nan ultrafast phase transition into a hidden ferroelectric phase can be\ndynamically induced in the quantum paraelectric SrTiO$_3$. The induced lowering\nin crystal symmetry yields dramatic changes in the phonon excitation spectra.\nOur results demonstrate collective coherent control over material structure, in\nwhich a single-cycle field drives ions along the microscopic pathway leading\ndirectly to their locations in a new crystalline phase on an ultrafast\ntimescale.",
        "positive": "Pushing thermal conductivity to its lower limit in crystals with simple\n  structures: Materials with low thermal conductivity usually have complex crystal\nstructures. Herein we experimentally find that a simple crystal structure\nmaterial AgTlI2 (I4/mcm) owns an extremely low thermal conductivity of 0.25\nW/mK at room temperature. To understand this anomaly, we perform in-depth\ntheoretical studies based on ab initio molecular dynamics simulations and\nanharmonic lattice dynamics. We find that the unique atomic arrangement and\nweak chemical bonding provide a permissive environment for strong oscillations\nof Ag atoms, leading to a considerable rattling behavior and giant lattice\nanharmonicity. This feature is also verified by the experimental probability\ndensity function refinement of single-crystal diffraction. The particularly\nstrong anharmonicity breaks down the conventional phonon gas model, giving rise\nto non-negligible wavelike phonon behaviors in AgTlI2 at 300 K. Intriguingly,\nunlike many strongly anharmonic materials where a small propagative thermal\nconductivity is often accompanied by a large diffusive thermal conductivity, we\nfind an unusual coexistence of ultralow propagative and diffusive thermal\nconductivities in AgTlI2 based on the thermal transport unified theory. This\nstudy underscores the potential of simple crystal structures in achieving low\nthermal conductivity and encourages further experimental research to enrich the\nfamily of materials with ultralow thermal conductivity."
    },
    {
        "anchor": "Electronic, vibrational, and electron-phonon coupling properties in\n  SnSe$_2$ and SnS$_2$ under pressure: The tin-selenide and tin-sulfide classes of materials undergo multiple\nstructural transitions under high pressure leading to periodic lattice\ndistortions, superconductivity, and topologically non-trivial phases, yet a\nnumber of controversies exist regarding the structural transformations in these\nsystems. We perform first-principles calculations within the framework of\ndensity functional theory and a careful comparison of our results with\navailable experiments on SnSe$_2$ reveals that the apparent contradictions\namong high-pressure results can be attributed to differences in experimental\nconditions. We further demonstrate that under hydrostatic pressure a $\\sqrt{3}\n\\times \\sqrt{3} \\times 1$ superstructure can be stabilized above 20 GPa in\nSnS$_2$ via a periodic lattice distortion as found recently in the case of\nSnSe$_2$, and that this pressure-induced phase transition is due to the\ncombined effect of Fermi surface nesting and electron-phonon coupling at a\nmomentum wave vector $\\mathbf{q}$ = $(1/3, 1/3, 0)$. In addition, we\ninvestigate the contribution of nonadiabatic corrections on the calculated\nphonon frequencies, and show that the quantitative agreement between theory and\nexperiment for the high-energy $A_{1g}$ phonon mode is improved when these\neffects are taken into account. Finally, we examine the nature of the\nsuperconducting state recently observed in SnSe$_2$ under nonhydrostatic\npressure and predict the emergence of superconductivity with a comparable\ncritical temperature in SnS$_2$ under similar experimental conditions.\nInterestingly, in the periodic lattice distorted phases, the critical\ntemperature is found to be reduced by an order of magnitude due to the\nrestructuring of the Fermi surface.",
        "positive": "Pressure-induced phase transitions and electronic properties Cd2V2O7: We report a density-functional theory study of the structural and electronic\nproperties of Cd2V2O7 under high-pressure conditions. The calculations have\nbeen performed by using first-principle calculations with the CRYSTAL program.\nThe occurrence of two structural phase transitions, at 0.3 and 10.9 GPa, is\nproposed. The crystal structure of the different high-pressure phases is\nreported. Interestingly a cubic pyrochlore-type structure is predicted to\nstabilize under compression. The two phase transitions involve substantial\nchanges in the coordination polyhedra of Cd and V. We have also determined the\ncompressibility and room-temperature equation of state of the three polymorphs\nof Cd2V2O7. According to our systematic electronic band-structure calculations,\nat ambient conditions Cd2V2O7 is an indirect wide band-gap material with a\nband-gap energy of 4.39 eV. In addition, the pressure dependence of the band\ngap has been determined. In particular, we have found that after the second\nphase transition the band gap decreases abruptly to a value of 2.56 eV."
    },
    {
        "anchor": "Entropy based fingerprint for local crystalline order: We introduce a new fingerprint that allows distinguishing between liquid-like\nand solid-like atomic environments. This fingerprint is based on an approximate\nexpression for the entropy projected on individual atoms. When combined with a\nlocal enthalpy, this fingerprint acquires an even finer resolution and it is\ncapable of discriminating between different crystal structures.",
        "positive": "An Investigation into the Kinetics of $Li^+$ Ion Migration in\n  Garnet-Type Solid State Electrolyte: $Li_7La_3Zr_2O_{12}$: An all solid-state thin film lithium ion battery has been touted the holy\ngrail for energy storage technology ever since the inception of the first one\nin 1986 by Keiichi Kanehori. Solid-state batteries provide the distinct\nadvantage of outperforming current technology by having a simpler composition,\nbeing easier and cheaper to manufacture, safer and having a higher theoretical\ngravimetric and volumetric energy density. The commercialization of this\ntechnology however, is plagued by its own set of challenges, primarily low\nionic conductivity and interfacial stability of the solid-state electrolyte\nseparating the anode and cathode, a small electrochemical window and sub-par\nmechanical properties. In the last decade considerable progress has been made\nin remedying these issues with garnet-type electrolytes, especially\nLi7La3Zr2O12 (LLZO), having emerged the leading contender. This has prompted\nrenewed effects into the field of solid-state ionic's and maximizing the ionic\nconductivity of LLZO by modifying its properties, primarily by means of doping\nwith a varying degree of success. Carving a clear road ahead requires an\nin-depth understanding of the origin of the high Li+ ion conductivity, the\nprimary means of investigating which is by first-principle methods. In this\nterm paper we try to gain insight into the origin of mechanisms at play that\ndrive the collective migration of Li+ ions in LLZO using a first-principles\napproach, to gain a deeper understanding and appreciation for optimizing its\nproperties for use in next-generation energy storage systems."
    },
    {
        "anchor": "Band-like Electron Transport with Record-High Mobility in the TCNQ\n  family: In highest quality organic single-crystal field-effect transistors, electron\ntransport occurs in the band-like regime, with the carrier mobility increasing\nupon lowering temperature. Neither the microscopic nature of this regime, nor\nwhy it occurs only in a small number of materials is currently understood.\nHere, comparative studies of closely related materials, exhibiting high-quality\nreproducible transport properties are needed. We performed a study of electron\ntransport in single-crystals of different TCNQ (tetracyanoquinodimethane)\nmolecules, combined with band structure calculations. We show that F2-TCNQ\ndevices exhibit very high electron mobility and an unprecedented increase in\nmobility upon cooling, whereas in TCNQ and F4-TCNQ the mobility is\nsubstantially lower and decreases upon cooling. We analyze the crystal and\nelectronic structures of these materials and find that F2-TCNQ crystals are\nindeed ideal to achieve outstanding transport properties. Our analysis also\nshows that to understand the difference between the three materials, studying\ntheir band structure is not sufficient, and that the electron-phonon coupling\nneeds to be investigated as well. Besides the outstanding transport properties\nof F2-TCNQ, a key result of our work is the identification of the Fx-TCNQ\nfamily as a paradigm to investigate the most fundamental aspects of electronic\ntransport in organic crystals.",
        "positive": "Conductance relaxation in GeBiTe - slow thermalization in an open\n  quantum system: This work describes the microstructure and transport properties of GeBiTe\nfilms with emphasis on their out-of-equilibrium behavior.\nPersistent-photoconductivity (PPC), previously studied in the phase-change\ncompound GeSbTe is also quite prominent in this system. Much weaker PPC\nresponse is observed in the pure GeTe compound and when alloying GeTe with\neither In or Mn. Films made from these compounds share the same\ncrystallographic structure, the same p-type conductivity, a similar\ncompositional disorder extending over mesoscopic scales, and similar mosaic\nmorphology. The enhanced PPC response exhibited by the Sb and Bi alloys may\ntherefore be related to their common chemistry. PPC is observable in GeBiTe\nfilms at the entire range of sheet resistances studied in this work. The excess\nconductance produced by a brief exposure to infrared illumination decays with\ntime as a stretched-exponential (Kohlrausch law). Intrinsic electron-glass\neffects on the other hand, are observable in thin films of GeBiTe only for\nsamples that are strongly-localized just like it was noted with the seven\nelectron-glasses previously studied. These include a memory-dip which is the\ndefining attribute of the phenomenon. The memory-dip in GeBiTe is the widest\namong the germanium-telluride alloys studied to date consistent with the high\ncarrier-concentration of this compound. The thermalization process exhibited in\neither, the PPC-state or in the electron-glass regime is sluggish but the\ntemporal law of the relaxation from the out-of-equilibrium state is distinctly\ndifferent. Coexistence of the two phenomena give rise to some non-trivial\neffects, in particular, the visibility of the memory-dip is enhanced in the\nPPC-state. The relation between this effect and the dependence of the\nmemory-effect magnitude on the ratio between the interparticle-interaction and\nquench-disorder is discussed."
    },
    {
        "anchor": "First principles elastic constants and electronic structure of\n  alpha-Pt_2Si and PtSi: We have carried out a first principles study of the elastic properties and\nelectronic structure for two room-temperature stable Pt silicide phases,\ntetragonal alpha-Pt_2Si and orthorhombic PtSi. We have calculated all of the\nequilibrium structural parameters for both phases: the a and c lattice\nconstants for alpha-Pt_2Si and the a, b, and c lattice constants and four\ninternal structural parameters for PtSi. These results agree closely with\nexperimental data. We have also calculated the zero-pressure elastic constants,\nconfirming prior results for pure Pt and Si and predicting values for the six\n(nine) independent, non-zero elastic constants of alpha-Pt_2Si (PtSi). These\ncalculations include a full treatment of all relevant internal displacements\ninduced by the elastic strains, including an explicit determination of the\ndimensionless internal displacement parameters for the three strains in\nalpha-Pt_2Si for which they are non-zero. We have analyzed the trends in the\ncalculated elastic constants, both within a given material as well as between\nthe two silicides and the pure Pt and Si phases. The calculated electronic\nstructure confirms that the two silicides are poor metals with a low density of\nstates at the Fermi level, and consequently we expect that the Drude component\nof the optical absorption will be much smaller than in good metals such as pure\nPt. This observation, combined with the topology found in the first principles\nspin-orbit split band structure, suggests that it may be important to include\nthe interband contribution to the optical absorption, even in the infrared\nregion.",
        "positive": "Photostrictive materials: Light-matter interactions that lead to nonthermal changes in size of the\nsample constitute a photostrictive effect in many compounds. The photostriction\nphenomenon was observed in four main groups of materials, ferroelectrics,\npolar, and non-polar semiconductors, as well as in organic-based materials that\nare reviewed here. The key mechanisms of photostriction and its dependence on\nseveral parameters and perturbations are assessed. The major literature of the\nphotostriction is surveyed, and the review ends with a summary of the proposed\ntechnical applications."
    },
    {
        "anchor": "Crystal-Chemical Origins of the Ultrahigh Conductivity of Metallic\n  Delafossites: Despite their highly anisotropic complex-oxidic nature, certain delafossite\ncompounds (e.g., PdCoO2, PtCoO2) are the most conductive oxides known, for\nreasons that remain poorly understood. Their room-temperature conductivity can\nexceed that of Au, while their low-temperature electronic mean-free-paths reach\nan astonishing 20 microns. It is widely accepted that these materials must be\nultrapure to achieve this, although the methods for their growth (which produce\nonly small crystals) are not typically capable of such. Here, we first report a\nnew approach to PdCoO2 crystal growth, using chemical vapor transport methods\nto achieve order-of-magnitude gains in size, the highest structural qualities\nyet reported, and record residual resistivity ratios (>440). Nevertheless, the\nfirst detailed mass spectrometry measurements on these materials reveal that\nthey are not ultrapure, typically harboring 100s-of-parts-per-million impurity\nlevels. Through quantitative crystal-chemical analyses, we resolve this\napparent dichotomy, showing that the vast majority of impurities are forced to\nreside in the Co-O octahedral layers, leaving the conductive Pd sheets highly\npure (~1 ppm impurity concentrations). These purities are shown to be in\nquantitative agreement with measured residual resistivities. We thus conclude\nthat a previously unconsidered \"sublattice purification\" mechanism is essential\nto the ultrahigh low-temperature conductivity and mean-free-path of metallic\ndelafossites.",
        "positive": "The interface between silicon and a high-k oxide: The ability to follow Moore's Law has been the basis of the tremendous\nsuccess of the semiconductor industry in the past decades. To date, the\ngreatest challenge for device scaling is the required replacement of silicon\ndioxide-based gate oxides by high-k oxides in transistors. Around 2010 high-k\noxides are required to have an atomically defined interface with silicon\nwithout any interfacial SiO2 layer. The first clean interface between silicon\nand a high-K oxide has been demonstrated by McKee et al. Nevertheless, the\ninterfacial structure is still under debate. Here we report on first-principles\ncalculations of the formation of the interface between silicon and SrTiO3 and\nits atomic structure. Based on insights into how the chemical environment\naffects the interface, a way to engineer seemingly intangible electrical\nproperties to meet technological requirements is outlined. The interface\nstructure and its chemistry provide guidance for the selection process of other\nhigh-k gate oxides and for controlling their growth. Our study also shows that\natomic control of the interfacial structure can dramatically improve the\nelectronic properties of the interface. The interface presented here serves as\na model for a variety of other interfaces between high-k oxides and silicon."
    },
    {
        "anchor": "Tuning Magnetic Properties Polycrystalline of PtCo Alloys Films with Pt: We experimentally investigated disordered PtxCo1-x (here x: 0.4, 0.5 and 0.6)\nalloy thin films magnetic properties which depended on Pt content. The magnetic\nproperties of PtCo films were described with two effects, one of them is the\nhybridization between Co 3d and Pt 5d energy levels and it causes Pt magnetic\npolarization. The second one is the high spin orbit coupling constant of Pt\nwhich increases the ratio of magnetic orbital moment to spin moment. We\ninvestigated magnetic properties considering these effects by vibrating sample\nmagnetometer (VSM) and ferromagnetic resonance (FMR) techniques.",
        "positive": "Controlling protein crystal growth rate by means of temperature: We have proposed a model to analyze the growth kinetics of lysozyme\ncrystals/aggregates under non-isothermal conditions. The model was formulated\nthrough an analysis of the entropy production of the growth process which was\nobtained by taking into account the explicit dependence of the free energy on\nthe temperature. We found that the growth process is coupled with temperature\nvariations resulting in a novel Soret-type effect. We identified the surface\nentropy of the crystal/aggregate as a decisive ingredient controlling the\nbehavior of the average growth rate as a function of temperature. The behavior\nof the Gibbs free energy as a function of temperature is also analyzed. The\nagreement between theory and experiments is very good in the range of\ntemperatures considered."
    },
    {
        "anchor": "Stress balance in nano-patterned N/Cu(001) surfaces: We employ helium atom scattering (HAS) and density functional theory (DFT)\nbased on the ultrasoft pseudopotential scheme and the plane-wave basis set to\ninvestigate the strain and stress balance in nano-patterned N/Cu(001) surfaces.\nHAS shows that, with increasing N coverage (and decreasing stripe widths), the\nstress-relief-driven lateral expansion of the averaged lattice parameter within\nfinite-sized N-containing patches reduces from 3.5% to 1.8% and that, beyond a\ncritical exposure, the lateral expansion of the patches increases again\nslightly, to 2.4%. The latter implies that in this higher coverage range the\ncompressive stress is partially relieved via another mechanism, which turns out\nto be nucleation of Cu-vacancy trenches. In full agreement with the above and\nprevious experimental observations, DFT calculations show that an optimized\nN-induced c(2\\times2) structure has a net surface stress level of 4.2 N/m and\nsuch stress is effectively relieved when stripes of clean Cu(001) form along\nthe <100> direction or when trench-like steps of Cu atoms form along the <110>\ndirection. Additionally, the calculations demonstrate that (contrary to earlier\nsuggestions) rumpling displacements within the outermost Cu layer do not act to\nrelieve the compressive surface stress levels and that, while clock-like\ndisplacements could relieve stress levels, such displacements are energetically\nunstable.",
        "positive": "Second-phase nucleation on an edge dislocation: A model for nucleation of second phase at or around dislocation in a\ncrystalline solid is considered. The model employs the Ginzburg-Landau theory\nof phase transition comprising the sextic term in order parameter in the Landau\nfree energy. The ground state solution of the linearized time-independent\nGinzburg-Landau equation has been derived, through which the spatial variation\nof the order parameter has been delineated. Moreover, a generic phase diagram\nindicating a tricritical behavior near and away from the dislocation is\ndepicted. The relation between the classical nucleation theory and the\nGinzburg-Landau approach has been discussed, for which the critical formation\nenergy of nucleus is related to the maximal of the Landau potential energy. A\nnumerical example illustrating the application of the model to the case of\nnucleation of hydrides in zirconium alloys is provided."
    },
    {
        "anchor": "Specific many-electron effects in X-ray spectra of simple metals and\n  graphene: In this work the influence of many-electron effects on the shape of\ncharacteristic X-ray emission bands of the simple metals Mg and Al are examined\nby means of ab initio calculations and semi-empirical models. These approaches\nare also used for the analysis of C K-emission and absorption spectra of\ngraphene. Both, the dynamical screening of the core vacancy and the\nAuger-effect in the valence band (VB) have been taken into account. Dynamical\nscreening of the core vacancy by valence electrons (the so-called MND effect)\nis considered ab initio in the framework of density functional theory. The\nAuger effect in VB was taken into account within a semi-empirical method,\napproximating the quadratic dependence of the VB hole level width on the\ndifference between the level energy and the Fermi energy. All theoretical\nspectra are in very good agreement with available experimental data.",
        "positive": "Quasiparticle band structures and thermoelectric transport properties of\n  p-type SnSe: We used density functional and many-body perturbation theory to calculate the\nquasiparticle band structures and electronic transport parameters of p-type\nSnSe both for the low-temperature Pnma and high-temperature Cmcm phases. The\nPnma phase has an indirect band gap of 0.829 eV while the Cmcm has a direct\nband gap of 0.464 eV. Both phases exhibit multiple local band extrema within an\nenergy range comparable to the thermal energy of carriers from the global\nextrema. We calculated the electronic transport coefficients for single-crystal\nand polycrystalline materials to understand previous experimental measurements.\nWe also discuss the dependence of the transport coefficients on doping\nconcentration and temperature to identify doping conditions for optimal\nthermoelectric performance."
    },
    {
        "anchor": "Efficient Pourbaix diagrams of many-element compounds: Pourbaix diagrams have long been an essential tool for determining the phase\nstability of solids and their associated ionic species under electrochemical\nconditions. In recent years, Pourbaix diagrams have been used for applications\nranging from corrosion-resistance alloy design to electrocatalysis, and the\ndata from which they are generated has been enhanced by the availability of\nmaterials data in various online databases. However, generation of\nmulti-element Pourbaix diagrams has a critical bottleneck which makes 3-element\nsystems difficult to analyze quickly, and 4 and 5 element systems intractable.\nIn this work, we present a method for constructing Pourbaix diagrams which uses\na pre-processing step to circumvent the most egregious computational bottleneck\nand make many-element Pourbaix diagrams computationally efficient.",
        "positive": "Metal Cluster's Effect on the Optical Properties of Cesium Bromide Thin\n  Films: Cesium Bromide films grown of glass substrates by thermal evaporation showed\ninteresting optical properties. The UV-visible absorption spectra showed peaks\nwhich showed red shift with time. Structural and morphological studies\nsuggested decrease in grain size with time which was unusual. Theoretical\nsimulation shows the optical behaviour to be due to surface plasmon resonance\nresulting from Cesium clyindrical rods embedded in the films."
    },
    {
        "anchor": "Density-functional calculation of static screening in 2D materials: the\n  long-wavelength dielectric function of graphene: We calculate the long-wavelength static screening properties of both neutral\nand doped graphene in the framework of density-functional theory. We use a\nplane-wave approach with periodic images in the third dimension and truncate\nthe Coulomb interactions to eliminate spurious interlayer screening. We\ncarefully address the issue of extracting two dimensional dielectric properties\nfrom simulated three-dimensional potentials. We compare this method with\nanalytical expressions derived for two dimensional massless Dirac fermions in\nthe random phase approximation. We evaluate the contributions of the deviation\nfrom conical bands, exchange-correlation and local-fields. For momenta smaller\nthan twice the Fermi wavevector, the static screening of graphene within the\ndensity-functional perturbative approach agrees with the results for conical\nbands within random phase approximation and neglecting local fields. For larger\nmomenta, we find that the analytical model underestimates the static dielectric\nfunction by $\\approx 10%$, mainly due to the conical band approximation.",
        "positive": "Synthesis by molten salt method of the AFeO3 system (A = La, Gd) and its\n  structural, vibrational and internal hyperfine magnetic field\n  characterization: Polycrystalline samples of LaFeO3 and GdFeO3 were synthesized by the molten\nsalt method. Some properties and the quality of the resulting compounds were\ninvestigated. The crystal structure and purity of the samples was determined\nthrough X-ray diffraction and Rietveld analysis. The vibrational properties\nwere characterized by Raman and IR spectroscopy. M\\\"ossbauer spectroscopy was\nused to determine the ionic state of the Fe ions and the internal hyperfine\nmagnetic fields Considerable reduction of the heat treatment (temperature and\ntime) for the reaction to take place was achieved without detriment of the\nquality of the compounds."
    },
    {
        "anchor": "Thermopower of SnTe from Boltzmann Transport Calculations: The doping and temperature dependent thermopower of SnTe is calculated from\nthe first principles band structure using Boltzmann transport theory. We find\nthat the $p$-type thermopower is inferior to PbTe consistent with experimental\nobservations, but that the $n$-type thermopower is substantially more\nfavorable.",
        "positive": "Micro-Structured Two-Component 3D Metamaterials with Negative\n  Thermal-Expansion Coefficient from Positive Constituents: Controlling the thermal expansion of materials is of great technological\nimportance. Uncontrolled thermal expansion can lead to failure or irreversible\ndestruction of structures and devices. In ordinary crystals, thermal expansion\nis governed by the asymmetry of the microscopic binding potential, which cannot\nbe adjusted easily. In artificial crystals called metamaterials, thermal\nexpansion can be controlled by structure. Here, following previous theoretical\nwork, we fabricate three-dimensional two-component polymer microlattices by\nusing gray-tone laser lithography. We perform cross-correlation analysis of\noptical microscopy images taken at different sample temperatures. The derived\ndisplacement-vector field reveals that the thermal expansion and resulting\nbending of the bi-material beams leads to a rotation of the 3D chiral crosses\narranged onto a 3D checkerboard pattern within one metamaterial unit cell.\nThese rotations can over-compensate the expansion and lead to an effectively\nnegative thermal length-expansion coefficient for all positive constituents\nevidencing a striking level of thermal-expansion control."
    },
    {
        "anchor": "Spin orbit precession damping in transition metal ferromagnets: We provide a simple explanation, based on an effective field, for the\nprecession damping rate due to the spin-orbit interaction. Previous effective\nfield treatments of spin-orbit damping include only variations of the state\nenergies with respect to the magnetization direction, an effect referred to as\nthe breathing Fermi surface. Treating the interaction of the rotating spins\nwith the orbits as a perturbation, we include also changes in the state\npopulations in the effective field. In order to investigate the quantitative\ndifferences between the damping rates of iron, cobalt, and nickel, we compute\nthe dependence of the damping rate on the density of states and the spin-orbit\nparameter. There is a strong correlation between the density of states and the\ndamping rate. The intraband terms of the damping rate depend on the spin-orbit\nparameter cubed while the interband terms are proportional to the spin-orbit\nparameter squared. However, the spectrum of band gaps is also an important\nquantity and does not appear to depend in a simple way on material parameters.",
        "positive": "Spin-glass behavior in Shastry-Sutherland lattice of\n  Tm$_\\textbf{2}$Cu$_\\textbf{2}$In: The spin-glass behavior in the ferromagnetic phase of $\\mathrm{Tm_2Cu_2In}$\nwas investigated by dc-, ac-magnetization, and non-equilibrium dynamics\ncharacterizations. Arc-melted polycrystalline compound of $\\mathrm{Tm_2Cu_2In}$\ncrystallizes in $\\mathrm{Mo_2FeB_2}$-type tetragonal structure (space group\n$P_4/mbm$). The temperature variation dc-magnetization exhibits a ferromagnetic\nbehavior with Curie temperature $T_C$ = 32.5 K. The zero-field cooled (ZFC) and\nfield cooled (FC) magnetic curves show a thermomagnetic irreversible behavior\nbelow $T_C$. The field dependence of irreversible temperature follows\nAlmeida-Thouless line. The frequency and ac-driven field-dependent anomalies in\nac-susceptibility results indicate the existence of spin-glass state in\n$\\mathrm{Tm_2Cu_2In}$. The time dependence of magnetization further supports\nthe spin-glass behavior observed in $\\mathrm{Tm_2Cu_2In}$. The frequency\ndependence of the freezing temperature in the real part of ac-susceptibility\nhas been analyzed on the basis power-law divergence and Vogel-Fulcher law. The\nobtained results revealed that $\\mathrm{Tm_2Cu_2In}$ belongs to a ferromagnetic\ncanonical spin-glass class of compounds."
    },
    {
        "anchor": "Intrinsic localized modes in two atomic chain; reduction of cubic\n  anharmonicity for gap modes: Analytical theory of large size intrinsic localized modes (ILMs) in\nanharmonic two-atomic chain is presented. It is shown that ILMs with\nfrequencies close to the borders of phonon gap are govern by quartic\nanharmonicity while the effect of cubic anharmonicity is essentially reduced.\nThis reduction effect is a consequence of small amplitude of vibrations of\nevery second atom. As a result, an ILM cannot split down from the optical\nphonon band, in contradiction with the commonly accepted point of view. But it\ncan spit up from the top of the acoustic phonon band making possible the\nexistence of the ILM with the frequencies above the top of this band. It is\npredicted that analogous reduction of cubic anharmonicity should exist\ngenerally for even ILMs with the middle atom being at rest; it may allow the\nexistence of ILMs with the frequencies above the top of the phonon spectrum in\ndifferent lattices with realistic atomic pair-potentials.",
        "positive": "From AC-STEM Image to 3D Structure: A Systematic Analysis of Au55\n  nanocluster: Aberration-corrected scanning electron microscopy (AC-STEM) can provide\nvaluable information on the atomic structure of nanoclusters, an essential\ninput for gaining an understanding of their physical and chemical properties. A\nsystematic method is presented here for the extraction of atom coordinates from\nan AC-STEM image in a way that is general enough to be applicable to irregular\nstructures. The two-dimensional information from the image is complemented with\nan approximate description of the atomic interactions so as to construct a\nthree-dimensional structure and, at a final stage, the structure is refined\nusing electron density functional theory (DFT) calculations. The method is\napplied to an AC-STEM image of Au55. Analysis of the local structure shows that\nthe cluster is a combination of a part with icosahedral structure elements and\na part with local atomic arrangement characteristic of crystal packing,\nincluding a segment of a flat surface facet. The energy landscape of the\ncluster is explored in calculations of minimum energy paths between the optimal\nfit structure and other candidates generated in the analysis. This reveals low\nenergy barriers for conformational changes, showing that such transitions can\noccur on laboratory timescale even at room temperature and lead to large\nchanges in the AC-STEM image. The paths furthermore reveal additional cluster\nconfigurations, some with lower DFT energy and providing nearly as good fit to\nthe experimental image."
    },
    {
        "anchor": "Avalanches and force drops in displacement-driven compression of porous\n  glasses: Similarities between force-driven compression experiments of porous materials\nand earthquakes have been recently proposed. In this manuscript, we measure the\nacoustic emission during displacement-driven compression of a porous glass. The\nenergy of acoustic-emission events shows that the failure process exhibits\navalanche scale-invariance and therefore follows the Gutenberg-Richter law. The\nresulting exponents do not exhibit significant differences with respect the\nforce-driven case. Furthermore, the force exhibits an avalanche-type behaviour\nfor which the force drops are power-law distributed and correlated with the\nacoustic emission events.",
        "positive": "Unusual pressure-induced periodic lattice distortion in SnSe$_2$: We performed high pressure x-ray diffraction (XRD), Raman, and transport\nmeasurements combined with first-principles calculations to investigate the\nbehavior of tin diselenide (SnSe$_2$) under compression. The obtained\nsingle-crystal XRD data indicate the formation of a $(1/3,1/3,1)$-type\nsuperlattice above 17 GPa. According to our density functional theory results,\nthe pressure-induced transition to the commensurate periodic lattice distortion\n(PLD) phase is due to the combined effect of strong Fermi surface nesting and\nelectron-phonon coupling at a momentum wave vector $\\mathbf{q}=(1/3,1/3,1)$. In\ncontrast, similar PLD transitions associated with charge density wave (CDW)\norderings in transition metal dichalcogenides (TMDs) do not involve significant\nFermi surface nesting. The discovered pressure-induced PLD is quite remarkable,\nas pressure usually suppresses CDW phases in related materials. Our findings,\ntherefore, provide new playgrounds to study the intricate mechanisms governing\nthe emergence of PLD in TMD-related materials."
    },
    {
        "anchor": "Suspension of Nanoparticles in SU-8 and Characterization of\n  Nanocomposite Properties: Gold nanospheres, single wall carbon nanotubes (SWNT), and diamonoids were\nphyically incorporated into the negative photoresist SU-8. the mixtures were\nspin cast onto silicon or aluminium coated silicon wafers. ASTM standard D638\ntensile specimens were lithographically patterned in the materials and then\nreleased from the substrate using Microchem'Omnicoat or an anodic metal\ndissolution process. the residual stresses, elastic moduli, and viscosity of\nthe SU-8. Resistivity measurements of SU-8/SWNT nanocomposites were also\ninvestigates. We found the effective modulus and viscosity of the SU-8 test\nspecimens decreases with the addition of diamantane and SWNTs. Additionally,\nthe SU-8/SWNT nanocomposites showed changes in resistivity with increased\nstrain, suggesting a gauge factor for the 1 wt% SU-8/SWNT nanocomposite of\napproximately 2-4.",
        "positive": "Exchange bias effect of ferro-/antiferromagnetic heterostructures: The exchange bias (EB) effect was discovered 60 years ago by Meiklejohn and\nBean. Meanwhile the EB effect has become an integral part of modern magnetism\nwith implications for basic research and for numerous device applications. The\nEB effect was the first of its kind which relates to an interface effect\nbetween two different classes of materials, here between a ferromagnet and an\nantiferromagnet. Here we review fundamental aspects of the exchange bias\neffect."
    },
    {
        "anchor": "Graphene field-effect-transistors with high on/off current ratio and\n  large transport band gap at room temperature: Graphene is considered to be a promising candidate for future\nnano-electronics due to its exceptional electronic properties. Unfortunately,\nthe graphene field-effect-transistors (FETs) cannot be turned off effectively\ndue to the absence of a bandgap, leading to an on/off current ratio typically\naround 5 in top-gated graphene FETs. On the other hand, theoretical\ninvestigations and optical measurements suggest that a bandgap up to a few\nhundred meV can be created by the perpendicular E-field in bi-layer graphenes.\nAlthough previous carrier transport measurements in bi-layer graphene\ntransistors did indicate a gate-induced insulating state at temperature below 1\nKelvin, the electrical (or transport) bandgap was estimated to be a few meV,\nand the room temperature on/off current ratio in bi-layer graphene FETs remains\nsimilar to those in single-layer graphene FETs. Here, for the first time, we\nreport an on/off current ratio of around 100 and 2000 at room temperature and\n20 K, respectively in our dual-gate bi-layer graphene FETs. We also measured an\nelectrical bandgap of >130 and 80 meV at average electric displacements of 2.2\nand 1.3 V/nm, respectively. This demonstration reveals the great potential of\nbi-layer graphene in applications such as digital electronics,\npseudospintronics, terahertz technology, and infrared nanophotonics.",
        "positive": "Observation of Antiferromagnetic Magnon Pseudospin Dynamics and the\n  Hanle effect: We report on experiments demonstrating coherent control of magnon spin\ntransport and pseudospin dynamics in a thin film of the antiferromagnetic\ninsulator hematite utilizing two Pt strips for all-electrical magnon injection\nand detection. The measured magnon spin signal at the detector reveals an\noscillation of its polarity as a function of the externally applied magnetic\nfield. We quantitatively explain our experiments in terms of diffusive magnon\ntransport and a coherent precession of the magnon pseudospin caused by the\neasy-plane anisotropy and the Dzyaloshinskii-Moriya interaction. This\nexperimental observation can be viewed as the magnonic analogue of the\nelectronic Hanle effect and the Datta-Das transistor, unlocking the high\npotential of antiferromagnetic magnonics towards the realization of rich\nelectronics-inspired phenomena."
    },
    {
        "anchor": "Valley Degree of Freedom in Two-Dimensional van der Waals Materials: Layered materials can possess valleys that are indistinguishable from one\nanother except for the momentum. These valleys are individually addressable in\nmomentum space at the K and K' points in the first Brillouin zone. Such valley\naddressability opens up the possibility of utilizing the momentum state of\nquasi-particles as a completely new paradigm in quantum and classical\ninformation processing. This review focuses on the physics behind valley\npolarization and talks about carriers of valley degree of freedom (VDF) in\nlayered materials. Then we provide a detailed survey of simple spectroscopic\ntechniques commonly utilized to identify and manipulate valley polarization in\nvan der Waals layered materials. Finally, we conclude with the recent\ndevelopments towards the manipulation of VDF for device application and\nassociated challenges.",
        "positive": "Critical Integrated Raman Scattering Intensity near the cubic-tetragonal\n  phase transition in Strontium Titanate: Emphasizing the contribution of Professor Roger A Cowley, FRS to the Theory\nof Raman Scattering from crystals, the development of the Theory of Raman\ncattering since 1928 has been briefly discussed. Some experimental studies of\nStrontium Titanate using Inelastic Neutron Scattering, Raman Scattering,\nElectro- paramagnetic resonance measurement and X-ray & Gamma Ray techniques\nhas been briefly discussed. Using Schwabl's semi-phenomenological theory for\nthe soft mode and central peak, we have developed (a) a one-phonon Green's\nfunction exhibiting the three peaked structure and (b) a two phonon Green's\nfunction involving one hard mode under damped quasiharmonic phonon and one\nthree peaked soft-mode phonon. We have developed the pre-cursor order induced\nRaman scattering near the displacive phase transition in terms of Green's\nfunctions. Using Group Theory, we have predicted the Raman-active modes in\nStrontium Titanate contributing to Critical Raman Scattering near hard-mode\nfrequencies above and below critical temperature. We have calculated the\nCritical Integrated Raman Scattering Intensity and the Two-phonon Background\nRaman Scattering Intensity near hard-mode frequencies above and below the\ncritical temperature. The results show the same trends as observed in some of\nthe experimental observations."
    },
    {
        "anchor": "Origin of large moments in Mn$_x$Si$_{1-x}$ at small x: Recently, the magnetic moment/Mn, $M$, in Mn$_x$Si$_{1-x}$ was measured to be\n5.0 $\\mu_B$/Mn, at $x$ =0.1%. To understand this observed $M$, we investigate\nseveral Mn$_x$Si$_{1-x}$ models of alloys using first-principles density\nfunctional methods. The only model giving $M = 5.0$ was a 513-atom cell having\nthe Mn at a substitutional site, and Si at a second-neighbor interstitial site.\nThe observed large moment is a consequence of the weakened d-p hybridization\nbetween the Mn and one of its nearest neighbor Si atoms, resulting from the\nintroduction of the second-neighbor interstitial Si. Our result suggests a way\nto tune the magnetic moments of transition metal doped semiconductors.",
        "positive": "Origin of the Significant Impact of Ta on the Creep Resistance of FeCrNi\n  Alloys: Heat resistant FeCrNi alloys are widely used in the petrochemical industry\nbecause they exhibit a unique combination of creep and oxidation resistance at\ntemperatures exceeding 900$^\\circ$C. Their creep properties are often optimized\nby micro-additions of carbide forming elements. In the present work, the\ninfluence of Ta micro-additions has been experimentally investigated both on\nas-cast and aged microstructures to understand the origin of the significant\nimpact of this element on the creep resistance. Calculations with thermocal\nsoftware were also carried out to support experimental data. It is shown that a\nsmall addition of Ta is beneficial as it increases the volume fraction of\nstable MC carbides. We demonstrate also that additions of Ta may have a\ndramatic effect on the thermal stability of microstructures. This is attributed\nto a smaller equilibrium volume fraction of M23C6 and more pronounced\nheterogeneous precipitation at MC/matrix interfaces. The influence on the creep\nproperties in then discussed."
    },
    {
        "anchor": "Rehabilitation of PBE-GGA for Layered Materials: The structural and energetic properties of layered materials propose a\nchallenge to density functional theory with common semilocal approximations to\nthe exchange-correlation. By combining the most-widely used semilocal\ngeneralized gradient approximation (GGA), Perdew--Burke--Ernzerhof (PBE), with\nthe revised Vydrov--Van Voorhis non-local correlation functional (rVV10), both\nexcellent structural and energetic properties of 28 layered materials were\nrecovered with a judicious parameter selection. We term the resulting\nfunctional as PBE+rVV10L with \"L\" denoting for layered materials. Such\ncombination is not new, and involves only refitting a single global parameter,\nhowever the resulting excellency suggests such corrected PBE for many aspects\nof theoretical studies on layered materials. For comparison, we also present\nthe results for PBE+rVV10 where the parameter is determined by the 22\ninteraction energies between molecules.",
        "positive": "Investigation of charge states and multiferroicity in Fe-doped h-YMnO3: Polycrystalline YMn1-xFexO3 (YMFO_x) (0 <= x <= 0.1) compounds have been\nprepared in single phase and characterized by synchrotron X-ray diffraction,\nX-ray absorption near edge spectroscopy, magnetization, and dielectric\nmeasurements. Iron-substitution in hexagonal YMnO3 causes intra-lattice changes\nexceeding those of the lattice cell. XANES provide mixed-valence Mn3+/Mn4+ and\nFe4+ charge states in these manganites, consistent with the observed decrease\nof the effective magnetic moment with Fe-doping. Magnetization M(T) evidence\nantiferromagnetic (AFM) ordering of the specimens with little weak\nferromagnetism, and the metrices of exchange interaction suppress with\nFe-doping, attributed to the lengthening of the Mn-O planar bond lengths.\nDielectric {\\epsilon}'(T) results showing highly doping-dependent anomaly at\nT_N indicate linear magneto-electric coupling."
    },
    {
        "anchor": "Photo-induced high-temperature order-disorder phase transition in CaSnO3\n  perovskite revealed by Raman spectroscopy: Calcium stannate perovskite (CaSnO3) has been studied by Raman spectroscopy\nat two excitation wavelengths (514.5 nm and 632.8 nm). A new first-order\norder-disorder phase transition induces Raman frequency shifts and line width\ndoubling at 121C on heating (94C on cooling), seen in experiments using the\n514.5 nm line of an Ar+-ion laser. The transition is also seen when using a\n623.8 nm He-Ne laser and by differential scanning calorimetry (DSC), but\nwithout strong order-disorder character, indicating that the phase transition\nis dependent on photo-excitation. High-temperature powder X-ray diffraction\nmeasurements provide thermal expansion coefficients of ax = 13.9 x 10-6 K-1, ay\n= 2.7 x 10-6 K-1, az = 14.3 x 10-6 K-1. The phase transition is postulated to\nbe associated with photo-excited charged and conductive nanoscale ferroelectric\norder-disorder. As such, CaSnO3 could represent the first in a new class of\noptoelectronic materials with additional potential photocatalytic properties.",
        "positive": "Controlled Coupling and Occupation of Silicon Atomic Quantum Dots: It is discovered that the zero-dimensional character of the silicon atom\ndangling bond (DB) state allows controlled formation and occupation of a new\nform of quantum dot assemblies. Whereas on highly doped n-type substrates\nisolated DBs are negatively charged, it is found that Coulomb repulsion causes\nDBs separated by less than ~2 nm to experience reduced localized charge. The\nunoccupied states so created allow a previously unobserved electron\ntunnel-coupling of DBs, evidenced by a pronounced change in the time-averaged\nview recorded by scanning tunneling microscopy. Direct control over net\nelectron occupation and tunnel-coupling of multi-DB ensembles through\nseparation controlled is demonstrated. Through electrostatic control, it is\nshown that a pair of tunnel-coupled DBs can be switched from a symmetric\nbi-stable state to one exhibiting an asymmetric electron occupation. Similarly,\nthe setting of an antipodal state in a square assembly of four DBs is achieved,\ndemonstrating at room temperature the essential building block of a quantum\ncellular automata device."
    },
    {
        "anchor": "Faceting diagram for Ag segregation induced nanofaceting at an\n  asymmetric Cu tilt grain boundary: In this work, we experimentally establish the isothermal nanofacet evolution\nat an asymmetric tilt grain boundary in the Cu-Ag system using a diffusion\ncouple approach. We investigate the nanofacet formation along the grain\nboundary in dependence of the Ag solute excess concentration. The initial grain\nboundary dissociates into asymmetric Ag-lean segments and Ag-rich symmetric\n(210) segments. Increasing Ag excess leads to an increase in Ag-rich facet\nsegment length, while the length of the asymmetric facets remains constant.\nFrom this, we construct a grain boundary nanofaceting diagram deduced from our\nexperiments relating local atomic structure, overall inclination and Ag solute\nexcess.",
        "positive": "Measuring Temperature Gradients over Nanometer Length Scales: When a quantum dot is subjected to a thermal gradient, the temperature of\nelectrons entering the dot can be determined from the dot's thermocurrent if\nthe conductance spectrum and background temperature are known. We demonstrate\nthis technique by measuring the temperature difference across a 15 nm quantum\ndot embedded in a nanowire. This technique can be used when the dot's energy\nstates are separated by many kT and will enable future quantitative\ninvestigations of electron-phonon interaction, nonlinear thermoelectric\neffects, and the effciency of thermoelectric energy conversion in quantum dots."
    },
    {
        "anchor": "Cu$_{1-x}$Fe$_x$O: Hopping Transport And Ferromagnetism: Single phase, sol-gel prepared Cu1-xFexO (0<x<0.125) are characterized in\nterms of structural, electronic and magnetic properties. Using dielectric and\nmagnetic studies we investigate the coupling of electron and spin. The\nelectrical conductivities and activation energies are studied with increasing\nFe content. Modeling of experimental conductivity data emphasizes on a single\nhopping mechanism for all samples except x=0.125, which have two activation\nenergies. Hole doping is confirmed from Hall effect [1] and by confirming a\nmajority Fe3+ substitution of Cu2+ in CuO from XPS studies. Such a substitution\nresults in stabilized ferromagnetism. Fe substitution introduces variation in\ncoercivity as an intrinsic magnetic property in Fe-doped CuO, and not as a\nsecondary impurity phase.",
        "positive": "A p-type Heusler compound: Growth, structure, and properties of\n  epitaxial thin NiYBi films on MgO(100): Epitaxial semiconducting NiYBi thin films were directly prepared on MgO(100)\nsubstrates by magnetron sputtering. The intensity ratio of the (200) and (400)\ndiffraction peaks, I(200)/I(400) = 2.93, was close to the theoretical value\n(3.03). The electronic structure of NiYBi was calculated using WIEN2k and a\nnarrow indirect band gap of width 210 meV was found. The valence band spectra\nof the films obtained by linear dichroism in hard X-ray photoelectron\nspectroscopy exhibit clear structures that are in good agreement with the\ncalculated band structure of NiYBi."
    },
    {
        "anchor": "Origin of ferroelectricity in high-$T_c$ magnetic ferroelectric CuO: Cupric oxide is a unique magnetic ferroelectric material with a transition\ntemperature significantly higher than the boiling point of liquid nitrogen.\nHowever, the mechanism of high-T$_c$ multiferroicity in CuO remains puzzling.\nIn this paper, we clarify the mechanism of high-T$_c$ multiferroicity in CuO,\nusing combined first-principles calculations and an effective Hamiltonian\nmodel. We find that CuO contains two magnetic sublattices, with strong\nintrasublattice interactions and weakly frustrated intersublattice\ninteractions, which may represent one of the main reasons for the high ordering\ntemperature of the compound. The weak spin frustration leads to incommensurate\nspin excitations that dramatically enhance the entropy of the mutliferroic\nphase and eventually stabilize that phase in CuO.",
        "positive": "Atomistic simulations of heat transport in real-scale silicon nanowire\n  devices: Utilizing atomistic lattice dynamics and scattering theory, we study thermal\ntransport in nanodevices made of 10 nm thick silicon nanowires, from 10 to 100\nnm long, sandwiched between two bulk reservoirs. We find that thermal transport\nin devices differs significantly from that of suspended extended nanowires, due\nto phonon scattering at the contact interfaces. We show that thermal\nconductance and the phonon transport regime can be tuned from ballistic to\ndiffusive by varying the surface roughness of the nanowires and their length.\nIn devices containing short crystalline wires phonon tunneling occurs and\nenhances the conductance beyond that of single contacts."
    },
    {
        "anchor": "A path-integral molecular dynamics simulation of diamond: Diamond is studied by path integral molecular dynamics simulations of the\natomic nuclei in combination with a tight-binding Hamiltonian to describe its\nelectronic structure and total energy. This approach allows us to quantify the\ninfluence of quantum zero-point vibrations and finite temperatures on both the\nelectronic and vibrational properties of diamond. The electron-phonon coupling\nmediated by the zero-point vibration reduces the direct electronic gap of\ndiamond by 10 %. The calculated decrease of the direct gap with temperature\nshows good agreement with the experimental data available up to 700 K.\nAnharmonic vibrational frequencies of the crystal have been obtained from a\nlinear-response approach based on the path integral formalism. In particular,\nthe temperature dependence of the zone-center optical phonon has been derived\nfrom the simulations. The anharmonicity of the interatomic potential produces a\nred shift of this phonon frequency.At temperatures above 500 K, this shift is\noverestimated in comparison to available experimental data. The predicted\ntemperature shift of the elastic constant c_{44} displays reasonable agreement\nwith the available experimental results.",
        "positive": "Multiple scattering by cylinders immersed in fluid: high order\n  approximations for the effective wavenumbers: Acoustic wave propagation in a fluid with a random assortment of identical\ncylindrical scatterers is considered. While the leading order correction to the\neffective wavenumber of the coherent wave is well established at dilute areal\ndensity ($n_0 $) of scatterers, in this paper the higher order dependence of\nthe coherent wavenumber on $n_0$ is developed in several directions. Starting\nfrom the quasi-crystalline approximation (QCA) a consistent method is described\nfor continuing the Linton and Martin formula, which is second order in $n_0$,\nto higher orders. Explicit formulas are provided for corrections to the\neffective wavenumber up to O$(n_0^4)$. Then, using the QCA theory as a basis,\ngeneralized self consistent schemes are developed and compared with self\nconsistent schemes using other dynamic effective medium theories. It is shown\nthat the Linton and Martin formula provides a closed self-consistent scheme,\nunlike some other approaches."
    },
    {
        "anchor": "Enhanced heat transfer with core-shell metal dielectric nanoparticles: Heat transfer from irradiated metallic nanoparticles is relevant to a broad\narray of applications ranging from water desalination to photoacoustics. The\nefficacy of such processes relies on the ability of these nanoparticles to\nabsorb the pulsed illuminating light and to quickly transfer energy to the\nenvironment. Here we show that compared to homogeneous gold nanoparticles\nhaving the same size, gold-silica core-shell nanoparticles enable heat\ntransfers to liquid water that are faster. We reach this conclusion by\nconsidering both analytical and numerical calculations. The key factor\nexplaining enhanced heat transfer is the direct interfacial coupling between\nmetal electrons and silica phonons. We discuss how to obtain fast heating of\nwater in the vicinity of the particle and show that optimal conditions involve\nnanoparticles with thin silica shells irradiated by ultrafast laser pulses. Our\nfindings should serve as guides for the optimization of thermoplasmonic\napplications of core-shell nanoparticles.",
        "positive": "Tuning magnetocrystalline anisotropy of Fe$_{3}$Sn by alloying: The electronic structure, magnetic properties and phase formation of\nhexagonal ferromagnetic Fe$_{3}$Sn-based alloys have been studied from first\nprinciples and by experiment. The pristine Fe$_{3}$Sn compound is known to\nfulfill all the requirements for a good permanent magnet, except for the\nmagnetocrystalline anisotropy energy (MAE). The latter is large, but planar,\ni.e. the easy magnetization axis is not along the hexagonal c direction,\nwhereas a good permanent magnet requires the MAE to be uniaxial. Here we\nconsider Fe$_{3}$Sn$_{0.75}$M$_{0.25}$, where M= Si, P, Ga, Ge, As, Se, In, Sb,\nTe and Bi, and show how different dopants on the Sn sublattice affect the MAE\nand can alter it from planar to uniaxial. The stability of the doped Fe$_{3}$Sn\nphases is elucidated theoretically via the calculations of their formation\nenthalpies. A micromagnetic model is developed in order to estimate the energy\ndensity product (BH)max and coercive field $\\mu_{0}$H$_{c}$ of a potential\nmagnet made of Fe$_{3}$Sn$_{0.75}$Sb$_{0.25}$, the most promising candidate\nfrom theoretical studies. The phase stability and magnetic properties of the\nFe$_{3}$Sn compound doped with Sb and Mn has been checked experimentally on the\nsamples synthesised using the reactive crucible melting technique as well as by\nsolid state reaction. The Fe$_{3}$Sn-Sb compound is found to be stable when\nalloyed with Mn. It is shown that even small structural changes, such as a\nchange of the c/a ratio or volume, that can be induced by, e.g., alloying with\nMn, can influence anisotropy and reverse it from planar to uniaxial and back."
    },
    {
        "anchor": "Ab initio studies of the impact of the Debye-Waller factor on the\n  structural and dynamical properties of amorphous semiconductors: The case of\n  $a$-Si: This paper presents a first-principles study of the Debye-Waller factor and\nthe Debye temperature for amorphous silicon ($a$-Si) from lattice-dynamical\ncalculations and direct molecular-dynamics simulations using density-functional\ntheory (DFT). The effects of temperature and structural disorder on the\nintensity of the diffraction maxima and the vibrational mean-square\ndisplacement (MSD) of Si atoms are studied in the harmonic approximation, with\nparticular emphasis on the bond-length disorder, the presence of coordination\ndefects, and microvoids in $a$-Si networks. It has been observed that the MSDs\nassociated with tetrahedrally-bonded Si atoms are considerably lower than their\ndangling-bond counterparts -- originating from isolated and vacancy-induced\nclustered defects -- and those on the surface of microvoids, leading to an\nasymmetric non-gaussian tail in the distribution of atomic displacements. An\nexamination of the effect of anharmonicity on the MSD at high temperatures\nusing direct $ab$ $initio$ molecular-dynamics simulations (without the harmonic\napproximation) suggests that the vibrational motion in $a$-Si is practically\nunaffected by anharmonic effects at temperatures below 400 K, as far as the\npresent DFT calculations are concerned. The Debye temperature of $a$-Si is\nfound to be in the range of 488--541 K from specific-heat and MSD calculations\nusing first-principles lattice-dynamical calculations in the harmonic\napproximation, which matches closely with the experimental value of 487--528 K\nobtained from specific-heat measurements of $a$-Si at low temperatures.",
        "positive": "Symmetry breaking in hexagonal and cubic polymorphs of BaTiO3: BaTiO3 appears in cubic and hexagonal variants, both of which are\ncentrosymmetric. Samples of cubic BaTiO3 are known to exhibit breaking of the\ncentric symmetry locally and globally. It has been proposed that the local\nsymmetry breaking originates in polar regions, the precursors of the\nferroelectric phase. Origins of the macroscopic symmetry breaking, which are\nnot well understood, have been previously tentatively correlated with\ninhomogeneities in the samples, such as strain gradients that may align or\nredistribute objects such as charged point defects or polar regions making\nmaterial macroscopically polar. No such data are available for BaTiO3 with\nhexagonal symmetry. We compare dielectric, elastic, and pyroelectric properties\nof the two materials in polycrystalline form. In contrast to cubic BaTiO3,\nhexagonal BaTiO3 does not exhibit macroscopic pyroelectric response at room\ntemperature. This is consistent with apparent absence of polar regions in the\nhexagonal material and the fact that in hexagonal BaTiO3 strain rather then\npolarization is the order parameter for the phase transition into\nferroelectric-ferroelastic phase. The thermally stimulated currents measured in\nhexagonal and cubic BaTiO3, however, show that both materials exhibit\nnoncentric macroscopic symmetry. This result supports the idea that extrinsic\nfactors such as strain gradients, which are apparently common for both\nmaterials, may break the macroscopic symmetry, which may then lead to alignment\nand redistribution of polar regions or charged defects."
    },
    {
        "anchor": "Recipe for single-pair-Weyl-points phonons carrying the same chiral\n  charges: Recently, Wang et al. [Phys. Rev. B, 106, 195129 (2022)] challenged a widely\nheld belief in the field of Weyl physics, demonstrating that\nsingle-pair-Weyl-points (SP-WPs) can exist in nonmagnetic spinless systems,\ncontrary to previous assumptions that they could only exist in magnetic\nsystems. Wang et al. observed that the SP-WPs with opposite and even chiral\ncharges (i.e., |C| = 2 or 4) could also exist in nonmagnetic spinless systems.\nIn this Letter, we present a novel finding in which SP-WPs have a partner,\nnamely a charged nodal surface, in nonmagnetic spinless systems. In contrast to\nprevious observations, we show that the SP-WPs can have uneven chiral charges\n(i.e., |C| = 1). We identify 6 (out of 230) space groups (SGs) that contain\nsuch SP-WPs by searching the encyclopedia of emergent particles in\nthree-dimensional crystals. Our finds were confirmed through the phonon spectra\nof two specific materials Zr3O (with SG 182) and NaPH2NO3 (with SG 173). This\ndiscovery broadens the range of materials that can host SP-WPs and applies to\nother nonmagnetic spinless crystals.",
        "positive": "Time-resolved investigation of magnetization dynamics of arrays of\n  non-ellipsoidal nanomagnets with a non-uniform ground state: We have performed time-resolved scanning Kerr microscopy (TRSKM) measurements\nupon arrays of square ferromagnetic nano-elements of different size and for a\nrange of bias fields. The experimental results were compared to micromagnetic\nsimulations of model arrays in order to understand the non-uniform precessional\ndynamics within the elements. In the experimental spectra two branches of\nexcited modes were observed to co-exist above a particular bias field. Below\nthe so-called crossover field, the higher frequency branch was observed to\nvanish. Micromagnetic simulations and Fourier imaging revealed that modes from\nthe higher frequency branch had large amplitude at the center of the element\nwhere the effective field was parallel to the bias field and the static\nmagnetization. Modes from the lower frequency branch had large amplitude near\nthe edges of the element perpendicular to the bias field. The simulations\nrevealed significant canting of the static magnetization and the effective\nfield away from the direction of the bias field in the edge regions. For the\nsmallest element sizes and/or at low bias field values the effective field was\nfound to become anti-parallel to the static magnetization. The simulations\nrevealed that the majority of the modes were de-localized with finite amplitude\nthroughout the element, while the spatial character of a mode was found to be\ncorrelated with the spatial variation of the total effective field and the\nstatic magnetization state. The simulations also revealed that the frequencies\nof the edge modes are strongly affected by the spatial distribution of the\nstatic magnetization state both within an element and within its nearest\nneighbors."
    },
    {
        "anchor": "Giant flexoelectric effect in two-dimensional boron-nitride sheets: We find, with the use of first-principles calculations, that a\nsingle-atom-thick boron-nitride (BN) sheet exhibits an unusual nonlinear\nelectromechanical effect: it becomes macroscopically polarized when bent\nout-of-plane. The direction of the induced polarization is in the plane of the\nfilm and it depends non-analitically on the corrugation wave vector k. The\nmagnitude of the polarization can reach very high values in spite of being at\nleast quadratic in atomic displacements due to BN sheets being able to tolerate\nlarge mechanical strains. The discovered effect can find many applications, in\nparticular, in a new type of efficient and reliable nanogenerators.",
        "positive": "Spin transfer torque on magnetic insulators: Recent experimental and theoretical studies focus on spin-mediated heat\ncurrents at interfaces between normal metals and magnetic insulators. We\nresolve conflicting estimates for the order of magnitude of the spin transfer\ntorque by first-principles calculations. The spin mixing conductance\nG^\\uparrow\\downarrow of the interface between silver and the insulating\nferrimagnet Yttrium Iron Garnet (YIG) is dominated by its real part and of the\norder of 10^14 \\Omega^-1m^-2, i.e. close to the value for intermetallic\ninterface, which can be explained by a local spin model."
    },
    {
        "anchor": "The Electronic Properties of Phosphorene/Graphene and\n  Phosphorene/Hexagonal Boron Nitride Heterostructures: Vertical integration of two-dimensional materials has recently emerged as an\nexciting method for the design of novel electronic and optoelectronic devices.\nUsing density functional theory, we investigatethe structural and electronic\nproperties of two heterostruc-tures, graphene/phosphorene (G/BP) and hexagonal\nboron nitride/phosphorene (BN/BP). We found that the interlayer distance,\nbinding energy, and charge transfer in G/BP and BN/BP are similar. Interlayer\nnoncovalentbonding is predicted due to the weak coupling between the pz orbital\nof BP and the {\\pi} orbital of graphene and BN. A small amount of electron\ntransfer from graphene and BN, scaling with the vertical strain, renders BP\nslightly n-doped for both heterostructures. Several attractive characteristics\nof BP, including direct band gap and linear dichroism, are preserved. However,\na large redistribution of electrostatic potential across the interface is\nobserved, which may significantly renormalize the carrier dynamics and affect\nthe excitonic behavior of BP. Our work suggests that graphene and BN can be\nused not only as an effective capping layer to protect BP from its structural\nand chemical degradation while still maintain its major electronic\ncharacteristics, but also as an active layer to tune the carrier dynamics and\noptical properties of BP.",
        "positive": "Magnetic skyrmion binning: When spin polarised electrons flow through a magnetic texture a transfer\ntorque is generated. We examine the effect of this torque on skyrmions and\nskyrmion bags, skyrmionic structures of arbitrary integer topological degree,\nin thin ferromagnetic films. Using micromagnetic simulations and analysis from\nthe well known Thiele equation we explore the potential for sorting or binning\nskyrmions of varying degrees mechanically. We investigate the applicability of\nthe Thiele equation to problems of this nature and derive a theory of skyrmion\ndeflection ordered by topological degree."
    },
    {
        "anchor": "Dopant-enhanced solid phase epitaxy in buried amorphous silicon layers: The kinetics of intrinsic and dopant-enhanced solid phase epitaxy (SPE) are\nstud- ied in buried amorphous Si (a-Si) layers in which SPE is not retarded by\nH. As, P, B and Al profiles were formed by multiple energy ion implantation\nover a con- centration range of 1 - 30 x 1019 /cm3. Anneals were performed in\nair over the temperature range 460-660 oC and the rate of interface motion was\nmonitored us- ing time resolved reflectivity. The dopant-enhanced SPE rates\nwere modeled with the generalized Fermi level shifting model using degenerate\nsemiconductor statis- tics. The effect of band bending between the crystalline\nand amorphous sides of the interface is also considered.",
        "positive": "Origin of Polar Distortion in LiNbO3-type \"Ferroelectric\" Metals: Role\n  of A-site Instability and Short-Range Interactions: Since conduction electrons of a metal screen effectively the local electric\ndipole moments, it was widely believed that the ferroelectric-like distortion\ncannot occur in metals. Recently, metallic LiOsO3, was discovered to be the\nfirst clear-cut example of an Anderson-Blount \"ferroelectric\" metal, which at\n140 K undergoes a ferroelectric-like structural transition similar to\ninsulating LiNbO3. This is very surprising because the mechanisms for\nstructural phase transitions are usually quite distinct in metals and\ninsulators. Through performing first principles calculations, here we reveal\nthat the local polar distortion in LiOsO3 is solely due to the instability of\nthe A-site Li atom, in contrast to the LiNbO3 case where the second order\nJahn-Teller effect of the B-site Nb ion also plays an additional role. More\nimportantly, the \"ferroelectric\"-like long range order of the local polar\ndistortion is found to be due to the predominantly ferroelectric short-range\npair interactions between the local polar modes which are not screened by\nconduction electrons. Furthermore, we predict that LiNbO3-type MgReO3 is also a\n\"ferroelectric\" metal, but with a much higher structural transition temperature\nby 391 K than LiOsO3. Our work not only unravels the origin of FE-like\ndistortion in LiNbO3-type \"ferroelectric\" metals, but also provides clue for\ndesigning other multi-functional \"ferroelectric\" metals."
    },
    {
        "anchor": "Lattice charge models and core level shifts in disordered alloys: Differences in core level binding energies between atoms belonging to the\nsame chemical species can be related to differences in their intra- and\nextra-atomic charge distributions, and differences in how their core holes are\nscreened. With this in mind, we consider the charge-excess functional model\n(CEFM) for net atomic charges in alloys [E. Bruno et al., Phys. Rev. Lett. 91,\n166401 (2003)]. We begin by deriving the CEFM energy function in order to\nelucidate the approximations which underpin this model. We thereafter consider\nthe particular case of the CEFM in which the strength of the `local\ninteractions' within all atoms are the same. We show that for binary alloys the\nground state charges of this model can be expressed in terms of charge transfer\nbetween all pairs of unlike atoms analogously to the linear charge model [R.\nMagri et al., Phys. Rev. B 42, 11388 (1990)]. Hence the model considered is a\ngeneralization of the linear charge model for alloys containing more than two\nchemical species. We then determine the model's unknown `geometric factors'\nover a wide range of parameter space. These quantities are linked to the nature\nof charge screening in the model, and we illustrate that the screening becomes\nincreasingly universal as the strength of the local interactions is increased.\nWe then use the model to derive analytical expressions for various physical\nquantities, including the Madelung energy and the disorder broadening in the\ncore level binding energies. These expressions are applied to ternary random\nalloys, for which it is shown that the Madelung energy and magnitude of\ndisorder broadening are maximized at the composition at which the two species\nwith the largest `electronegativity difference' are equal, while the remaining\nspecies having a vanishing concentration. This result is somewhat\ncounterintuitive with regards to the disorder broadening since it does not...",
        "positive": "Re-entrant phenomenon in diffuse ferroelectric,\n  $BaSn_{0.15}Ti_{0.85}O_{3}$ : Local structural insights and FORC study: From the phase diagram as proposed by Lei et.al., [J. App. Phys 101, 084105\n(2007)] a $BaSn_{0.15}Ti_{0.85}O_{3}$ is chosen showing a diffuse phase\ntransition between cubic to rhombohedral (C-R) near room temperature.\nDielectric analysis confirms a phase transition near room temperature ($T_{C}$\n$\\approx$ 290 K) and also frequency dispersion in dielectric constant is\nobserved towards low temperature. Polarization and first-order reversal curves\n(FORC) suggest that the system is in re-entrant phase at low temperatures. Put\ntogether, all these electrical characterization results points toward the\nrelaxor behavior in the re-entrant phase. Local probe techniques such as x-ray\nabsorption near edge spectroscopy, Raman and Mossbauer spectroscopy are\nemployed to investigate the local environment changes around this region of low\ntemperature dielectric anomaly. A simple ferroelectric exchange model\nexplaining the low temperature re-entrant behavior is presented from these\nresults."
    },
    {
        "anchor": "Nonreciprocity engineering in magnetostatic spin waves: Magnetostatic surface spin waves (MSSW) excited from a coplanar waveguide\nantenna travel in different directions with different amplitudes. This effect,\ncalled nonreciprocity of MSSW, has been investigated by micromagnetic\nsimulations. The ratio of amplitude of two counter propagating spin waves, the\nnonreciprocity parameter {\\kappa}, is obtained for different ferromagnetic\nmaterials, such as NiFe (Py), CoFeAl, yttrium iron garnet (YIG), and GaMnAs. A\ndevice schematic has been proposed in which {\\kappa} can be tuned to a large\nvalue by varying simple geometrical parameters of the device.",
        "positive": "Real-Time Stress Measurements in Lithium-ion Battery Negative-electrodes: Real-time stress evolution in a graphite-based lithium-ion battery\nnegative-electrode during electrolyte wetting and electrochemical cycling is\nmeasured through wafer-curvature method. Upon electrolyte addition, the\ncomposite electrode rapidly develops compressive stress of the order of 1-2 MPa\ndue to binder swelling; upon continued exposure, the stress continues to evolve\ntowards an apparent plateau. During electrochemical intercalation at a slow\nrate, the compressive stress increases with the electrode's state-of-charge,\nreaching a maximum value of 10 - 12 MPa. There appears to be an approximate\ncorrelation between the rate of stress rise and the staging behavior of the\nlithiated graphite. De-intercalation at a slow rate results in a similar linear\ndecrease in electrode stress. Tensile stress of a few MPa develops at the end\nof deintercalation in the first few cycles, after which the electrode remains\nunder compressive stress only. Although higher peak stresses are seen at high\nC-rates, the dependence appears to be relatively weak (up to 5C). These\nmeasurements reveal, for the first time, the nature of stress evolution in\npractical lithium-ion-battery electrodes and provide useful data to quantify\nthe driving force for mechanical damage that accrues in composite electrodes\nupon repeated cycling. While the reported results can serve as reference for\ncalibrating theoretical and computational models to predict electrode stress\nand damage evolution, the methodology demonstrated can be used to measure\nstresses and characterize fatigue damage in any composite lithium-ion-battery\nelectrode as well as optimize its microstructure to mitigate stress-related\ndamage mechanisms."
    },
    {
        "anchor": "Essential properties of AlCl4-related graphite intercalation compounds\n  of aluminum-ion-based battery cathodes: Up to now, many guest atoms/molecules/ions have been successfully synthesized\ninto graphite to form the various compounds. For example, alkali-atom graphite\nintercalation compounds are verified to reveal the stage-n structures,\nincluding LiC6n and LiM8n [M=K. Rb and Cs; n=1, 2, 3; 4]. On the other side,\nAlCl4-ion/molecule ones are examined to show stage-4 and stage-3 cases at room\nand lower temperatures, respectively. Stage-1 and stage-2 configurations, with\nthe higher intercalant concentrations, are unable to synthesize in experimental\nlaboratories. This might arise from the fact that it is quite difficult to\nbuild the periodical arrangements along the longitudinal z and transverse\ndirections simultaneously for the large ions or molecules. Our works are mainly\nfocused on stage-1 and stage-2 systems in terms of geometric and electronic\nproperties. The critical features, being associated with the atom-dominated\nenergy spectra and wave function within the specific energy ranges, the active\nmulti-orbital hybridization in distinct chemical bonds, and atom- &\norbital-decomposed van Hove singularities, will be thoroughly clarified by the\ndelicate simulations and analyses.",
        "positive": "Giant spin Hall angle in the Heusler alloy Weyl ferromagnet Co$_2$MnGa: Weyl semimetals are playing a major role in condensed matter physics due to\nexotic topological properties, and their coexistence with ferromagnetism may\nlead to enhanced spin-related phenomena. Here, the inverse spin Hall effect\n(ISHE) in the ferromagnetic Weyl-semimetal Heusler alloy Co$_2$MnGa was\ninvestigated at room temperature by means of electrical spin injection in\nlateral spin valve structures. Spin transport properties such as spin\npolarization and spin diffusion length in this material were precisely\nextracted in order to estimate the spin Hall angle $\\theta_{\\textrm{SH}}$,\nwhich was found to be $-0.19\\pm0.04$ and is among the highest reported for a\nferromagnet. Although this value is on the same order of magnitude of known\nheavy metals, the significantly higher resistivity of Co$_2$MnGa implies an\nimprovement on the magnitude of detection voltages, while its ferromagnetic\nnature allows controlling the intensity of SHE through the magnetization\ndirection. It was also shown that Onsager's reciprocity does not hold for this\nsystem, which is in part attributable to a different spin-dependent Hall\nconductivity for spin-up and spin-down carriers."
    },
    {
        "anchor": "Revealing the Predictive Power of Neural Operators for Strain Evolution\n  in Digital Composites: The demand for high-performance materials, along with advanced synthesis\ntechnologies such as additive manufacturing and 3D printing, has spurred the\ndevelopment of hierarchical composites with superior properties. However,\ncomputational modelling of such composites using physics-based solvers, while\nenabling the discovery of optimal microstructures, have prohibitively high\ncomputational cost hindering their practical application. To this extent, we\nshow that Neural Operators (NOs) can be used to learn and predict the strain\nevolution in 2D digital composites. Specifically, we consider three\narchitectures, namely, Fourier NO (FNO), Wavelet NO (WNO), and Multi-wavelet NO\n(MWT). We demonstrate that by providing a few initial strain frames as input,\nNOs can accurately predict multiple future time steps in an extremely\ndata-efficient fashion, especially WNO. Further, once trained, NOs forecast the\nstrain trajectories for completely unseen boundary conditions. Among NOs, only\nFNO offers super-resolution capabilities for estimating strains at multiple\nlength scales, which can provide higher material and pixel-wise resolution. We\nalso show that NOs can generalize to arbitrary geometries with finer domain\nresolution without the need for additional training. Based on all the results\npresented, we note that the FNO exhibits the best performance among the NOs,\nwhile also giving minimum inference time that is almost three orders magnitude\nlower than the conventional finite element solutions. Thus, FNOs can be used as\na surrogate for accelerated simulation of the strain evolution in complex\nmicrostructures toward designing the next composite materials.",
        "positive": "Magnetic, Optoelectronic, and Rietveld refined structural properties of\n  Al3+ substituted nanocrystalline Ni-Cu spinel ferrites: An experimental and\n  DFT based study: The nanocrystalline Ni0.7Cu0.3AlxFe2-xO4 (x=0.00: 0.02: 0.10) is prepared\nthrough the sol-gel autocombustion route.Both XRD and Rietveld confirm the\nsingle-phase cubic spinel structure of the investigated materials.Other\nstructural parameters refined by the Rietveld refinement analysis are\ncorroborated to single-phase cubic spinel formation of the NPs.Leveraging a\nvibrating sample magnetometer (VSM) the consequence of Al3+ substitution on the\nmagnetic parameters is studied.The saturation magnetization (MS) and Bohr\nmagneton are found to decrease with Al3+ substitution.The Remanence ratio and\ncoercivity (HC) are observed to be very low suggesting the materials are soft\nferromagnetic.First-principle calculations were carried out using the density\nfunctional theory (DFT) to demonstrate the optoelectronic behavior of the\nmaterials.The electronic bandgap is found low as Eg=2.99eV for the explored\nmaterials with observing defect states at 0.62eV.The optoelectronic properties\nof Al3+ substituted Ni-Cu ferrite NPs have been characterized through the DFT\nsimulation for the first time, demonstrating their potentiality for\noptoelectronic device applications.The materials' optical anisotropy is\nobserved along the x-axis, which manifests their tunability through\nlight-matter interaction."
    },
    {
        "anchor": "Symmetry and optical selection rules in graphene quantum dots: Graphene quantum dots (GQD's) have optical properties which are very\ndifferent from those of an extended graphene sheet. In this Article we explore\nhow the size, shape and edge--structure of a GQD affect its optical\nconductivity. Using representation theory, we derive optical selection rules\nfor regular-shaped dots, starting from the symmetry properties of the current\noperator. We find that, where the x- and y-components of the current operator\ntransform with the same irreducible representation (irrep) of the point group -\nfor example in triangular or hexagonal GQD's - the optical conductivity is\nindependent of the polarisation of the light. On the other hand, where these\ncomponents transform with different irreps - for example in rectangular GQD's -\nthe optical conductivity depends on the polarisation of light. We find that\nGQD's with non-commuting point-group operations - for example dots of\nrectangular shape - can be distinguished from GQD's with commuting point-group\noperations - for example dots of triangular or hexagonal shape - by using\npolarized light. We carry out explicit calculations of the optical conductivity\nof GQD's described by a simple tight--binding model and, for dots of\nintermediate size, \\textcolor{blue}{($10 \\lesssim L \\lesssim 50\\ \\text{nm}$)}\nfind an absorption peak in the low--frequency range of the spectrum which\nallows us to distinguish between dots with zigzag and armchair edges. We also\nclarify the one-dimensional nature of states at the van Hove singularity in\ngraphene, providing a possible explanation for very high exciton-binding\nenergies. Finally we discuss the role of atomic vacancies and shape asymmetry.",
        "positive": "Pathways Towards Ferroelectricity in Hafnia: The question of whether one can systematically identify (previously unknown)\nferroelectric phases of a given material is addressed, taking hafnia (HfO$_2$)\nas an example. Low free energy phases at various pressures and temperatures are\nidentified using a first-principles based structure search algorithm.\nFerroelectric phases are then recognized by exploiting group theoretical\nprinciples for the symmetry-allowed displacive transitions between non-polar\nand polar phases. Two orthorhombic polar phases occurring in space groups\n$Pca2_1$ and $Pmn2_1$ are singled out as the most viable ferroelectric phases\nof hafnia, as they display low free energies (relative to known non-polar\nphases), and substantial switchable spontaneous electric polarization. These\nresults provide an explanation for the recently observed surprising\nferroelectric behavior of hafnia, and reveal pathways for stabilizing\nferroelectric phases of hafnia as well as other compounds."
    },
    {
        "anchor": "Transferable classical force field for pure and mixed metal halide\n  perovskites parameterized from first principles: Many key features in photovoltaic perovskites occur in relatively long time\nscales and involve mixed compositions. This requires realistic but also\nnumerically simple models. In this work we present a transferable classical\nforce field to describe the mixed hybrid perovskite\nMA$_x$FA$_{1-x}$Pb(Br$_y$I$_{1-y}$)$_3$ for variable composition ($\\forall x,y\n\\in [0,1]$). The model includes Lennard-Jones and Buckingham potentials to\ndescribe the interactions between the atoms of the inorganic lattice and the\norganic molecule, and the AMBER model to describe intramolecular atomic\ninteractions. Most of the parameters of the force field have been obtained by\nmeans of a genetic algorithm previously developed to parameterize the\nCsPb(Br$_x$I$_{1-x}$)$_3$ perovskite. The algorithm finds the best parameter\nset that simultaneously fits the DFT energies obtained for several crystalline\nstructures with moderate degrees of distortion with respect to the equilibrium\nconfiguration. The resulting model reproduces correctly the XRD patterns, the\nexpansion of the lattice upon I/Br substitution and the thermal expansion\ncoefficients. We use the model to run classical molecular dynamics simulations\nwith up to 8600 atoms and simulation times of up to 40~ns. From the simulations\nwe have extracted the ion diffusion coefficient of the pure and mixed\nperovskites, presenting for the first time these values obtained by a fully\ndynamical method using a transferable model fitted to first principles\ncalculations. The values here reported can be considered as the theoretical\nupper limit for ion migration dynamics induced by halide vacancies in\nphotovoltaic perovskite devices under operational conditions.",
        "positive": "Exploration of Characteristic Temperature Contributions to Metallic\n  Glass Forming Ability: Various combinations of characteristic temperatures, such as the glass\ntransition temperature, liquidus temperature, and crystallization temperature,\nhave been proposed as predictions of the glass forming ability of metal alloys.\nWe have used statistical approaches from machine learning to systematically\nexplore a wide range of possible characteristic temperature functions for\npredicting glass forming ability in the form of critical casting diameter,\n$D_{max}$. Both linear and non-linear models were used to learn on the largest\ndatabase of $D_{max}$ values to date consisting of 747 compositions. We find\nthat no combination of temperatures for features offers a better prediction of\n$D_{max}$ in a machine learning model than the temperatures themselves, and\nthat regression models suffer from poor performance on standard machine\nlearning metrics like root mean square error (minimum value of $3.3 \\pm 0.1$\n$mm$ for data with a standard deviation of 4.8 $mm$). Examination of the errors\nvs. database size suggest that a larger database may improve results, although\na database significantly larger than that used here would likely be required.\nShifting a focus from regression to categorization models learning from\ncharacteristic temperatures can be used to weakly distinguish glasses likely to\nbe above vs. below our database's median $D_{max}$ value of 4.0 $mm$, with a\nmean F1 score of $0.77 \\pm 0.02$ for this categorization. The overall weak\nresults on predicting $D_{max}$ suggests that critical cooling rate might be a\nbetter target for machine learning model prediction."
    },
    {
        "anchor": "Chemical bonding and electronic-structure in MAX phases as viewed by\n  X-ray spectroscopy and density functional theory: This is a critical review of MAX-phase carbides and nitrides from an\nelectronic-structure and chemical bonding perspective. This large group of\nnanolaminated materials is of great scientific and technological interest and\nexhibit a combination of metallic and ceramic features. These properties are\nrelated to the special crystal structure and bonding characteristics with\nalternating strong M-C bonds in high-density MC slabs, and relatively weak M-A\nbonds between the slabs. Here, we review the trend and relationship between the\nchemical bonding, conductivity, elastic and magnetic properties of the MAX\nphases in comparison to the parent binary MX compounds with the underlying\nelectronic structure probed by polarized X-ray spectroscopy. Spectroscopic\nstudies constitute important tests of the results of state-of-the-art\nelectronic structure density functional theory that is extensively discussed\nand are generally consistent. By replacing the elements on the M, A, or X-sites\nin the crystal structure, the corresponding changes in the conductivity,\nelasticity, magnetism and other materials properties makes it possible to\ntailor the characteristics of this class of materials by controlling the\nstrengths of their chemical bonds.",
        "positive": "Selenium / Tellurium Two-Dimensional Structures: from Isovalent Se\n  Dopants in Te to Atomically Thin Se Films: Two-dimensional (2D) elemental semiconductors have great potential for device\napplications, but their performance is limited by the lack of efficient doping\nmethods. Here, combining molecular beam epitaxy, scanning tunneling\nmicroscopy/spectroscopy, X-ray photoelectron spectroscopy, and density\nfunctional theory calculations, we investigate the evolution of the structural\nand electronic properties of 2D selenium/tellurium films with increased Se\ndosages on graphene/6H-SiC(0001) substrates. We found that Se atoms form\nisovalent dopants by replacing surface Te atoms, which introduces efficient\nelectron doping and lowers the work function of Te films. With the Se dosage\nincreasing, two types of elemental 2D crystalline Se structures, trigonal Se\nand Se8 molecular assembly films, are obtained on ultrathin Te films, which are\ndistinct from the amorphous Se acquired by depositing Se directly on\ngraphene/6H-SiC(0001). Our results shed light on tuning the electronic\nproperties of 2D elemental semiconductors by isovalent doping and constructing\nheterostructures of isovalent 2D elemental materials."
    },
    {
        "anchor": "Tunable macroscale structural superlubricity in two-layer graphene via\n  strain engineering: Achieving structural superlubricity in graphitic samples of macro-scale size\nis particularly challenging due to difficulties in sliding large contact areas\nof commensurate stacking domains. Here, we show the presence of macro-scale\nstructural superlubricity between two randomly stacked graphene layers produced\nby both mechanical exfoliation and CVD. By measuring the shifts of Raman peaks\nunder strain we estimate the values of frictional interlayer shear stress\n(ILSS) in the superlubricity regime (mm scale) under ambient conditions. The\nrandom incommensurate stacking, the presence of wrinkles and the mismatch in\nthe lattice constant between two graphene layers induced by the tensile strain\ndifferential are considered responsible for the facile shearing at the\nmacroscale. Furthermore, molecular dynamic simulations show that the stick-slip\nbehaviour does not hold for achiral shearing directions for which the ILSS\ndecreases substantially, supporting the experimental observations. Our results\npave the way for overcoming several limitations in achieving macroscale\nsuperlubricity in graphene.",
        "positive": "Role of Disorder in Mn:GaAs, Cr:GaAs, and Cr:GaN: We present calculations of magnetic exchange interactions and critical\ntemperature T_c in Mn:GaAs, Cr:GaAs and Cr:GaN. The local spin density\napproximation is combined with a linear-response technique to map the magnetic\nenergy onto a Heisenberg hamiltonion, but no significant further approximations\nare made. Special quasi-random structures in large unit cells are used to\naccurately model the disorder. T_c is computed using both a spin-dynamics\napproach and the cluster variation method developed for the classical\nHeisenberg model.\n  We show the following: (i) configurational disorder results in large\ndispersions in the pairwise exchange interactions; (ii) the disorder strongly\nreduces T_c; (iii) clustering in the magnetic atoms, whose tendency is\npredicted from total-energy considerations, further reduces T_c. Additionally\nthe exchange interactions J(R) are found to decay exponentially with distance\nR^3 on average; and the mean-field approximation is found to be a very poor\npredictor of T_c, particularly when J(R) decays rapidly. Finally the effect of\nspin-orbit coupling on T_c is considered. With all these factors taken into\naccount, T_c is reasonably predicted by the local spin-density approximation in\nMnGaAs without the need to invoke compensation by donor impurities."
    },
    {
        "anchor": "Simulation of coarsening in two-phase systems with dissimilar mobilities: In this work, we apply phase field simulations to examine the coarsening\nbehavior of morphologically complex two-phase microstructures in which the\nphases have highly dissimilar mobilities, a condition approaching that found in\nexperimental solid-liquid systems. Specifically, we consider a two-phase system\nat the critical composition ($50\\%$ volume fraction) in which the mobilities of\nthe two phases differ by a factor of 100. This system is simulated in two and\nthree dimensions using the Cahn-Hilliard model with a concentration-dependent\nmobility, and results are compared to simulations with a constant mobility. A\nmorphological transition occurs during coarsening of the two-dimensional system\n(corresponding to a thin film geometry) with dissimilar mobilities, resulting\nin a system of nearly-circular particles of high-mobility phase embedded in a\nlow-mobility matrix. This morphological transition causes the coarsening rate\nconstant to decrease over time, which explains why a previous study found lack\nof agreement with the theoretical $t^{1/3}$ power law. Three-dimensional\nsystems with dissimilar mobilities resulted in bicontinuous microstructures\nthat evolve self-similarly, as determined by quantitative analysis of the\ninterfacial shape distribution. Coarsening kinetics in three dimensions agreed\nclosely with the $t^{1/3}$ power law after the initial transient stage. A model\nis derived to explain a nearly-linear relationship between the coarsening rate\nconstant and the variance of scaled mean curvature that is observed during this\ntransient stage.",
        "positive": "A New Kind of Atlas of Zeolite Building Blocks: We have analysed structural motifs in the Deem database of hypothetical\nzeolites, to investigate whether the structural diversity found in this\ndatabase can be well-represented by classical descriptors such as distances,\nangles, and ring sizes, or whether a more general representation of atomic\nstructure, furnished by the smooth overlap of atomic positions (SOAP) method,\nis required to capture accurately structure-property relations. We assessed the\nquality of each descriptor by machine-learning the molar energy and volume for\neach hypothetical framework in the dataset. We have found that SOAP with a\ncutoff-length of 6 \\AA, which goes beyond near-neighbor tetrahedra, best\ndescribes the structural diversity in the Deem database by capturing relevant\ninter-atomic correlations. Kernel principal component analysis shows that SOAP\nmaintains its superior performance even when reducing its dimensionality to\nthose of the classical descriptors, and that the first three kernel principal\ncomponents capture the main variability in the data set, allowing a 3D point\ncloud visualization of local environments in the Deem database. This ``cloud\natlas\" of local environments was found to show good correlations with the\ncontribution of a given motif to the density and stability of its parent\nframework. Local volume and energy maps constructed from the\nSOAP/machine-learning analyses provide new images of zeolites that reveal\nsmooth variations of local volumes and energies across a given framework, and\ncorrelations between local volume and energy in a given framework."
    },
    {
        "anchor": "The diffraction power of crystals with unknown atomic structures:\n  calculation and application in quantitative phase analysis: Quantitative phase analysis is one of the major applications of X-ray powder\ndiffraction. The essential principle of quantitative phase analysis is that the\ndiffraction intensity of a component phase in a mixture is proportional to its\ncontent. Nevertheless, the diffraction intensity of the component phases cannot\nbe compared with each other directly since each phase has its specific\ndiffraction power. The diffraction power of the unit cell of a crystal is well\nrepresented by the sum of the squared structure factors, which cannot be\ncalculated directly when the structure data is unavailable. Here a method was\ndemonstrated to calculate the diffraction power using only the chemical\ncontents in the unit cell of a crystal, which enables quantitative phase\nanalysis on a mixture sample consisting of crystalline phases with unknown\natomic structures.",
        "positive": "Nanocarbon for Energy Material Applications: N$_2$ Reduction Reaction: Nanocarbons are an important class of energy materials and one relevant\napplication is for the nitrogen reduction reaction, i.e., the direct synthesis\nof NH3 from N2 and H2O via photo- and electrocatalytic approaches. Ammonia is\nalso a valuable energy or hydrogen vector. This perspective paper analyses\ndevelopments in the field, limiting discussion to nanocarbon-based electrodes.\nThese aspects are discussed: i) active sites related to charge density\ndifferences on C atoms associated to defects/strains, ii) doping with\nheteroatoms, iii) introduction of isolated metal ions, iv) creation and in situ\ndynamics of metal oxide(hydroxide)/nanocarbon boundaries, and v) nanocarbon\ncharacteristics to control the interface. Discussion is focused on the\nperformances and mechanistic aspects. Aim is not a systematic state-of-the-art\nreport but to highlight the need to use a different perspective in studying\nthis challenging reaction by using selected papers. Notwithstanding the large\ndifferences in the proposed nature of the active sites, fall all within a\nrestricted range of performances, far from the targets. A holistic approach is\nemphasized to make a breakthrough advance."
    },
    {
        "anchor": "Symmetry, incommensurate magnetism and ferroelectricity: the case of the\n  rare-earth manganites RMnO3: The complete irreducible co-representations of the paramagnetic space group\nprovide a simple and direct path to explore the symmetry restrictions of\nmagnetically driven ferroelectricity. The method consists of a straightforward\ngeneralization of the method commonly used in the case of displacive modulated\nsystems and allows us to determine, in a simple manner, the full magnetic\nsymmetry of a given phase originated from a given magnetic order parameter. The\npotential ferroic and magneto-electric properties of that phase can then be\nestablished and the exact Landau free energy expansions can be derived from\ngeneral symmetry considerations. In this work, this method is applied to the\ncase of the orthorhombic rare-earth manganites RMnO3. This example will allow\nus to stress some specific points, such as the differences between commensurate\nor incommensurate magnetic phases regarding the ferroic and magnetoelectric\nproperties, the possible stabilization of ferroelectricity by a single\nirreducible order parameter or the possible onset of a polarization oriented\nparallel to the magnetic modulation. The specific example of TbMnO3 will be\nconsidered in more detail, in order to characterize the role played by the\nmagneto-electric effect in the mechanism for the polarization rotation induced\nby an external magnetic field.",
        "positive": "Three-dimensional Printing of Complex Graphite Structures: Graphite, with many industrial applications, is one of the widely\nsought-after allotropes of carbon. The sp2 hybridized and thermodynamically\nstable form of carbon forms a layered structure with strong in-plane carbon\nbonds and weak inter-layer van der Waals bonding. Graphite is also a\nhigh-temperature ceramic, and shaping them into complex geometries is\nchallenging, given its limited sintering behavior even at high temperatures.\nAlthough the geometric design of the graphite structure in many of the\napplications could dictate its precision performance, conventional synthesis\nmethods for formulating complex geometric graphite shapes are limited due to\nthe intrinsic brittleness and difficulties of high-temperature processing.\nHere, we report the development of colloidal graphite ink from commercial\ngraphite powders with reproducible rheological behavior that allows the\nfabrication of any complex architectures with tunable geometry and\ndirectionality via 3D printing at room temperature. The method is enabled via\nusing small amounts of clay, another layered material, as an additive, allowing\nthe proper design of the graphene ink and subsequent binding of graphite\nplatelets during printing. Sheared layers of clay are easily able to flow,\nadapt, and interface with graphite layers forming strong binding between the\nlayers and between particles that make the larger structures. The direct ink\nprinting of complex 3D architectures of graphite without further heat\ntreatments could lead to easy shape engineering and related applications of\ngraphite at various length scales, including complex graphite molds or\ncrucibles. The 3D printed complex graphitic structures exhibit excellent\nthermal, electrical, and mechanical properties, and the clay additive does not\nseem to alter these properties due to the excellent inter-layer dispersion and\nmixing within the graphite material."
    },
    {
        "anchor": "An Efficient DFT Solver for Nanoscale Simulations and Beyond: We present the One-orbital Ensemble Self-Consistent Field (OE-SCF) method, an\n{alternative} orbital-free DFT solver that extends the applicability of DFT to\nsystem sizes beyond the nanoscale while retaining the accuracy required to be\npredictive. OE-SCF is an iterative solver where the (typically computationally\nexpensive) Pauli potential is treated as an external potential and updated\nafter each iteration. Because only up to a dozen iterations are needed to reach\nconvergence, OE-SCF dramatically outperforms current orbital-free DFT solvers.\nEmploying merely a single CPU, we carried out the largest ab initio simulation\nfor silicon-based materials to date. OE-SCF is able to converge the energy of\nbulk-cut Si nanoparticles as a function of their diameter up to 16 nm, for the\nfirst time reproducing known empirical results. We model polarization and\ninterface charge transfer when a Si slab is sandwiched between two metal slabs\nwhere lattice matching mandates a very large slab size. Additionally, OE-SCF\nopens the door to adopt even more accurate functionals in orbital-free DFT\nsimulations while still tackling systems sizes beyond the nanoscale.",
        "positive": "Anisotropic properties of monolayer 2D materials: an overview from the\n  C2DB database: We analyze the occurrence of in-plane anisotropy in the electronic, magnetic,\nelastic and transport properties of more than one thousand 2D materials from\nthe C2DB database. We identify hundreds of anisotropic materials and classify\nthem according to their point group symmetry and degree of anisotropy. A\nstatistical analysis reveals that a lower point group symmetry and a larger\namount of different elements in the structure favour all types of anisotropies,\nwhich could be relevant for future materials design approaches. Besides, we\nidentify novel compounds, predicted to be easily exfoliable from a parent bulk\ncompound, with anisotropies that largely outscore those of already known 2D\nmaterials. Our findings provide a comprehensive reference for future studies of\nanisotropic response in atomically-thin crystals and point to new previously\nunexplored materials for the next generation of anisotropic 2D devices."
    },
    {
        "anchor": "Quantum Spin Hall Effect and Topological Phase Transition in\n  Two-Dimensional Square Transition Metal Dichalcogenides: Two-dimensional (2D) topological insulators (TIs) hold promise for\napplications in spintronics based on the fact that the propagation direction of\nedge electrons of a 2D TI is robustly linked to their spin origination. Here,\nwith the use of first-principles calculations, we predict a family of robust 2D\nTIs in monolayer square transition metal dichalcogenides (MoS2, MoSe2, MoTe2,\nWS2, WSe2, and WTe2). Sizeable intrinsic nontrivial bulk band gaps ranging from\n24 to 187 meV are obtained, guarantying the quantum spin Hall (QSH) effect\nobservable at room temperature in these new 2D TIs. Significantly different\nfrom most known 2D TIs with comparable band gaps, these sizeable energy gaps\noriginate from the strong spin-orbit interaction related to the pure d\nelectrons of the Mo/W atoms around the Fermi level. A single pair of\ntopologically protected helical edge states is established for the edge of\nthese systems with the Dirac point locating in the middle of the bulk band gap,\nand their topologically nontrivial states are also confirmed with nontrivial\ntopological invariant Z2 = 1. More interestingly, by controlling the applied\nstrain, a topological quantum phase transition between a QSH phase and a\nmetallic phase or a trivial insulating phase can be realized in these 2D\nmaterials, and the detailed topological phase diagram is established.",
        "positive": "Hybrid quantum photonics based on artificial atoms placed inside one\n  hole of a photonic crystal cavity: Spin-based quantum photonics promise to realize distributed quantum computing\nand quantum networks. The performance depends on efficient entanglement\ndistribution, where the efficiency can be boosted by means of cavity quantum\nelectrodynamics. The central challenge is the development of compact devices\nwith large spin-photon coupling rates and high operation bandwidth. Photonic\ncrystal cavities comprise strong field confinement but put high demands on\naccurate positioning of an atomic system in the mode field maximum. Color\ncenter in diamond, and in particular the negatively-charged Silicon-Vacancy\ncenter, emerged as a promising atom-like systems. Large spectral stability and\naccess to long-lived, nuclear spin memories enabled elementary demonstrations\nof quantum network nodes including memory-enhanced quantum communication. In a\nhybrid approach, we deterministically place SiV$^-$-containing nanodiamonds\ninside one hole of a one-dimensional, free-standing, Si$_3$N$_4$-based photonic\ncrystal cavity and coherently couple individual optical transitions to the\ncavity mode. We optimize the light-matter coupling by utilizing two-mode\ncomposition, waveguiding, Purcell-enhancement and cavity resonance tuning. The\nresulting photon flux is increased by more than a factor of 14 as compared to\nfree-space. The corresponding lifetime shortening to below 460 ps puts the\npotential operation bandwidth beyond GHz rates. Our results mark an important\nstep to realize quantum network nodes based on hybrid quantum photonics with\nSiV$^-$- center in nanodiamonds."
    },
    {
        "anchor": "Electrical current-driven pinhole formation and insulator-metal\n  transition in tunnel junctions: Current Induced Resistance Switching (CIS) was recently observed in thin\ntunnel junctions (TJs) with ferromagnetic (FM) electrodes and attributed to\nelectromigration of metallic atoms in nanoconstrictions in the insulating\nbarrier. The CIS effect is here studied in TJs with two thin (20 \\AA)\nnon-magnetic (NM) Ta electrodes inserted above and below the insulating\nbarrier. We observe resistance (R) switching for positive applied electrical\ncurrent (flowing from the bottom to the top lead), characterized by a\ncontinuous resistance decrease and associated with current-driven displacement\nof metallic ions from the bottom electrode into the barrier (thin barrier\nstate). For negative currents, displaced ions return into their initial\npositions in the electrode and the electrical resistance gradually increases\n(thick barrier state). We measured the temperature (T) dependence of the\nelectrical resistance of both thin- and thick-barrier states ($R_b$ and R$_B$\nrespectively). Experiments showed a weaker R(T) variation when the tunnel\njunction is in the $R_b$ state, associated with a smaller tunnel contribution.\nBy applying large enough electrical currents we induced large irreversible\nR-decreases in the studied TJs, associated with barrier degradation. We then\nmonitored the evolution of the R(T) dependence for different stages of barrier\ndegradation. In particular, we observed a smooth transition from tunnel- to\nmetallic-dominated transport. The initial degradation-stages are related to\nirreversible barrier thickness decreases (without the formation of pinholes).\nOnly for later barrier degradation stages do we have the appearance of metallic\npaths between the two electrodes that, however, do not lead to metallic\ndominated transport for small enough pinhole radius.",
        "positive": "State-of-the-art and prospects for intense red radiation from core-shell\n  InGaN/GaN nanorods: Core-shell nanorods (NRs) with InGaN/GaN quantum wells (QWs) are promising\nfor monolithic white light-emitting diodes and multicolor displays. Such\napplications, however, are still a challenge because intensity of red band is\ntoo weak as compared with blue and green ones. To clarify the problem, we have\nperformed power and temperature dependent, as well as time-resolved\nmeasurements of photoluminescence (PL) in NRs of different In content and\ndiameter. These studies have shown that the dominant PL bands originate from\nnonpolar and semipolar QWs, while a broad yellow-red band arises mostly from\ndefects in the GaN core. Intensity of red emission from the polar QWs at the NR\ntip is fatally small. Our calculation of electromagnetic field distribution\ninside the NRs shows a low density of photon states in the tip that suppresses\nthe red radiation. We suggest a design of hybrid NRs, in which polar QWs,\nlocated inside the GaN core, are pumped by UV-blue radiation of nonpolar QWs.\nPossibilities of radiative recombination rate enhancement by means of the\nPurcell effect are discussed."
    },
    {
        "anchor": "Basic formulation and first-principles implementation of nonlinear\n  magneto-optical effects: First-principles calculation of nonlinear magneto-optical effects has become\nan indispensable tool to reveal the geometric and topological nature of\nelectronic states and to understand light-matter interactions. While\nintriguingly rich physics could emerge in magnetic materials, further\nmethodological developments are required to deal with time-reversal symmetry\nbreaking, due to the degeneracy and gauge problems caused by symmetry and the\nlow-frequency divergence problem in the existing calculation formalism. Here we\npresent a gauge-covariant and low-frequency convergent formalism for the\nfirst-principles computation. Remarkably, this formalism generally works for\nboth non-magnetic and magnetic materials with or without band degeneracy.\nReliability and capability of our method are demonstrated by studying example\nmaterials (i.e., bilayers of MnBi$_2$Te$_4$ and CrI$_3$) and comparing with\npublished results. Moreover, an importance correction term that ensures gauge\ncovariance of degenerate states is derived, whose influence on physical\nresponses is systematically checked. Our method enables computation of\nnonlinear magneto-optical effects in magnetic materials and paves the way for\nexploring rich physics created by the interplay of light and magnetism.",
        "positive": "Ultraviolet luminescence of polycyclic aromatic hydrocarbons in\n  partially consolidated sol-gel silica glasses: Photoluminescence (PL) and Raman spectra of sol-gel-derived silica glasses\nwere studied in course of the consolidation of xerogel to dense glass. A number\nof ultraviolet PL bands in 3 eV - 4 eV region were found, which have not been\nobserved in pure silica glasses not exposed to carbon compounds. Such PL bands,\nsome of which exhibit distinct vibronic structures at room temperature, have\nbeen persistently reported in various high-surface porous or nanoparticle forms\nof SiO2. Based on their spectral shapes and decay kinetics properties, the\nstructured PL bands in the 3.7-3.8 eV and 3.1-3.3 eV regions are assigned to\npolycyclic hydrocarbons, naphthalene and pyrene, respectively, which are formed\nfrom ethanol molecules created by hydrolysis of tetraethoxysilane. These data\nsupport the hypothesis that PL activity of carbon-doped silica may be related\nto embedded aromatic carbon groups."
    },
    {
        "anchor": "Initial Stages of FeO Growth on Ru(0001): We study how FeO w\\\"{u}stite films on Ru(0001) grow by oxygen-assisted\nmolecular beam epitaxy at elevated temperatures (800-900 K). The nucleation and\ngrowth of FeO islands are observed in real time by low-energy electron\nmicroscopy (LEEM). When the growth is performed in an oxygen pressure of 10-6\nTorr, the islands are of bilayer thickness (Fe-O-Fe-O). In contrast, under a\npressure of 10-8 Torr, the islands are a single FeO layer thick. We propose\nthat the film thickness is controlled by the concentration of oxygen adsorbed\non the Ru. More specifically, when monolayer growth increases the adsorbed\noxygen concentration above a limiting value, its growth is suppressed.\nIncreasing the temperature at a fixed oxygen pressure decreases the density of\nFeO islands. However, the nucleation density is not a monotonic function of\noxygen pressure.",
        "positive": "High-temperature self-energy corrections to x-ray absorption spectra: Effects of finite-temperature quasiparticle self-energy corrections to x-ray\nabsorption spectra are investigated within the finite-temperature quasiparticle\nlocal density GW approximation up to temperatures $T$ of order the Fermi\ntemperature. To facilitate the calculations, we parametrize the quasiparticle\nself-energy using low-order polynomial fits. We show that temperature-driven\ndecrease in the electron lifetime substantially broadens the spectra in the\nnear-edge region with increasing $T$. However, the quasiparticle shift is most\nstrongly modified near the onset of plasmon excitations."
    },
    {
        "anchor": "Molecular Dynamics Modeling of Epoxy Resins using the Reactive Interface\n  Force Field: Predictive computational modeling of polymer materials is necessary for the\nefficient design of composite materials and the corresponding processing\nmethods. Molecular dynamics (MD) modeling is especially important for\nestablishing accurate processing-structure-property relationships for neat\nresins. For MD modeling of amorphous polymer materials, an accurate force field\nis fundamental to reliable prediction of properties. Reactive force fields, in\nwhich chemical bonds can be formed or broken, offer further capability in\npredicting the mechanical behavior of amorphous polymers subjected to\nrelatively large deformations. To this end, the Reactive Interface Force Field\n(IFF-R) has been recently developed to provide an efficient means to predict\nthe behavior of materials under these conditions. Although IFF-R has been\nproven to be accurate for some crystalline organic and inorganic systems, it\nhas not yet been proven to be accurate for amorphous polymer systems. The\nobjective of this study is to use IFF-R to predict the thermo-mechanical\nproperties of three different epoxy systems and validate with experimental\nmeasurements. The results indicate that IFF-R predicts thermo-mechanical\nproperties that agree closely with experiment. Therefore, IFF-R can be used to\nreliably establish mechanical properties of polymers on the molecular level for\nfuture design of new composite materials and processing methods.",
        "positive": "Electric field and Strain-induced Band-gap Engineering and Manipulation\n  of the Rashba Spin Splitting in Janus van der Waals Heterostructures: The compositional as well as structural asymmetries in Janus transition metal\ndichalcogenides (J-TMDs) and their van der Waals heterostructures (vdW HSs)\ninduce an intrinsic Rashba spin-splitting. We investigate the variation of\nband-gaps and the Rashba parameter in three different Janus heterostructures\nhaving AB-stacked Mo$XY$/W$XY$ ($X$, $Y$ = S, Se, Te; $X\\neq Y$) geometry with\na $Y-Y$ interface, using first-principles calculations. We consider the effect\nof external electric field and in-plane biaxial strain in tuning the strength\nof the intrinsic electric field, which leads to remarkable modifications of the\nband-gap and the Rashba spin-splitting. In particular, it is found that the\npositive applied field and compressive in-plane biaxial strain can lead to a\nnotable increase in the Rashba spin-splitting of the valence bands about the\n$\\Gamma$-point. Moreover, our \\textit{ab-initio} density functional theory\n(DFT) calculations reveal the existence of a type-II band alignment in these\nheterostructures, which remains robust under positive external field and\nbiaxial strain. These suggest novel ways of engineering the electronic,\noptical, and spin properties of J-TMD van der Waals heterostructures holding a\nhuge promise in spintronic and optoelectronic devices. Detailed $\\mathbf{k\\cdot\np}$ model analyses have been performed to investigate the electronic and spin\nproperties near the $\\Gamma$ and K points of the Brillouin zone."
    },
    {
        "anchor": "Spectroscopic Properties and STM Images of Carbon Nanotubes: We present a theoretical study of the role of the local environment in the\nelectronic properties of carbon nanotubes: isolated single- and multi-wall\nnanotubes, nanotube-ropes, tubes supported on gold and cutted to finite length.\nInteraction with the substrate or with other tubes does not alter the\nscanning-tunneling-microscopy (STM) patterns observed for isolated tubes.\nSTM-topographic images of topological defects (pentagon/heptagon pair) and\ntube-caps have also been studied. In both cases the obtained image depends on\nthe sign of the applied voltage and it can be described in terms of the\nprevious catalog of STM-images (interference between electronic waves scattered\nby the defect). We also have computed the electronic density of states for\nisolated tubes with different chiralities and radii confirming a correlation\nbetween the peak-structure in the DOS and the nanotube diameter, however the\nmetallic plateau in the DOS also depends on the nanotube chirality.\nFurthermore, the conduction and valence band structures are not fully\nsymmetrical to one another. In contrast to STM images, the interaction with the\nsubstrate does modify the energy levels of the nanotube. We observe opening of\nsmall pseudogaps around the Fermi level and broadening of the sharp van Hove\nsingularities of the isolated single-walled-nanotubes that can be used to\nextract useful information about the tube structure and bonding. The\ncombination of STM and spectroscopic studies opens a new technique to address\nthe electronic and structural properties of carbon and composite nanotubes.",
        "positive": "In-situ Nanoscale Characterization of Composition and Structure during\n  Formation of Ultrathin Nickel Silicide: We characterize composition and structure of ultrathin nickel silicide during\nformation from 3 nm Ni films on Si(100) using in-situ high resolution ion\nscattering and high resolution transmission electron microscopy. We show the\ntransition to occur in discrete steps, in which an intermediate phase is\nobserved within a narrow range of temperature from 230 oC to 290 oC. The film\ncomposition of this intermediate phase is found to be 50% Ni:50% Si, without\nevidence for long-range structure, indicating the film to be a homogeneous\nmonosilicide NiSi phase. The final phase is resemblant of the cubic disilicide\nNiSi2, but with slightly off-stoichiometric composition of 38% Ni and 62% Si.\nAlong the [100] axis, the lattices of the film and the substrate are found in\nperfect alignment. Due to the epitaxial growth of the silicide, a contraction\nof the c lattice constant of the film by 0.7-1% is detected."
    },
    {
        "anchor": "Structure of graphene oxide: thermodynamics versus kinetics: Graphene oxide (GO) is an important intermediate to prepare graphene and it\nis also a versatile material with various applications. However, despite its\nimportance, the detailed structure of GO is still unclear. For example,\nprevious theoretical studies based on energetics have suggested that hydroxyl\nchain is an important structural motif of GO, which, however, is found to be\ncontrary to nuclear magnetic resonance (NMR) experiment. In this study, we\ncheck both thermodynamic and kinetic aspects missed previously. First\nprinciples thermodynamics gives a free energy based stability ordering similar\nto that based on energetics, and hydroxyl chain is thus thermodynamically still\nfavorable. At the same time, by checking the calculated vibrational\nfrequencies, we note that hydroxyl chain structure is also inconsistent with\ninfrared experiment. Therefore, kinetics during GO synthesis is expected to\nmake an important role in GO structure. Transition state calculations predict\nlarge energy barriers between local minima, which suggests that experimentally\nobtained GO has a kinetically constrained structure.",
        "positive": "Growth mechanisms of GaN on the O-terminated ZnO(000-1) surfaces: We have investigated the stability of the 1ML-GaN on the O-polarity\nZnO(000-1) interface structure using the first-principles calculation. We have\nfound in our calculated results that the most stable structure for the 1ML-GaN\non the O-polarity ZnO(000-1) interface has the N-polarity. However, we have\nfound that the results of the adatom dynamics on the O-terminated ZnO(000-1)\nsurface shows the Ga-polarity. We find that the key to change the polarity of\nGaN crystal grown on the O-terminated ZnO(000-1) surface is the growth\ntemperature. We have suggested that the optimized initial growth condition for\nthe growth of the Ga-polarity GaN crystal on the O-terminated ZnO(000-1)\nsurface is under the suitable low temperature and the stoichiometric growth\ncondition. Experimental observations show that GaN grown on ZnO(000-1) by PLD\nat substrate temperatures below 300C has Ga-polarity, which is quite consistent\nwith the theoretical calculations"
    },
    {
        "anchor": "Long-Range Order Promotes Charge-Transfer Excitations in Donor/Acceptor\n  Co-Crystals: Electronic and optical properties of doped organic semiconductors are\ndominated by local interactions between donor and acceptor molecules. However,\nwhen such systems are in crystalline form, long-range order competes against\nshort-range couplings. In a first-principles study on three experimentally\nresolved bulk structures of quaterthiophene doped by (fluorinated)\ntetracyanoquinodimethane, we demonstrate the crucial role of long-range\ninteractions in donor/acceptor co-crystals. The band structures of the\ninvestigated materials exhibit direct band-gaps decreasing in size with\nincreasing amount of F atoms in the acceptors. The valence-band maximum and\nconduction-band minimum are found at the Brillouin zone boundary and the\ncorresponding wave-functions are segregated on donor and acceptor molecules,\nrespectively. With the aid of a tight-binding model, we rationalize that the\nmechanisms responsible for these behaviors, which are ubiquitous in\ndonor/acceptor co-crystals, are driven by long-range interactions. The optical\nresponse of the analyzed co-crystals is highly anisotropic. The absorption\nonset is dominated by an intense resonance corresponding to a charge-transfer\nexcitation. Long-range interactions are again responsible for this behavior,\nwhich enhances the efficiency of the co-crystals for photo-induced charge\nseparation and transport. In addition to these results, our study clarifies\nthat cluster models, accounting only for local interactions, cannot capture the\nrelevant impact of long-range order in donor/acceptor co-crystals.",
        "positive": "Mechanical Ringdown Studies of Large-Area Substrate-Transferred\n  GaAs/AlGaAs Crystalline Coatings: We investigated elastic loss in GaAs/AlGaAs multilayers to help determine the\nsuitability of these coatings for future gravitational wave detectors. We\nmeasured large ($\\approx 70$-mm diameter) substrate-transferred crystalline\ncoating samples with an improved substrate polish and bonding method. The\nelastic loss, when decomposed into bulk and shear contributions, was shown to\narise entirely from the bulk loss, $\\phi_{\\mathrm{Bulk}} = (5.33 \\pm\n0.03)\\times 10^{-4}$, with $\\phi_{\\mathrm{Shear}} = (0.0 \\pm 5.2) \\times\n10^{-7}$. These results predict the coating loss of an 8-mm diameter coating in\na 35-mm long cavity with a 250-$\\mu$m spot size (radius) to be\n$\\phi_{\\mathrm{coating}} = (4.78 \\pm 0.05) \\times 10^{-5}$, in agreement with\nthe published result from direct thermal noise measurement of\n$\\phi_{\\mathrm{coating}} = (4 \\pm 4) \\times 10^{-5}$. Bonding defects were\nshown to have little impact on the overall elastic loss."
    },
    {
        "anchor": "Quantitative determination of spin-dependent quasiparticle lifetimes and\n  electronic correlations in hcp cobalt: We report on a quantitative investigation of the spin-dependent quasiparticle\nlifetimes and electron correlation effects in ferromagnetic hcp Co(0001) by\nmeans of spin and angle-resolved photoemission spectroscopy. The experimental\nspectra are compared in detail to state-of-the-art many-body calculations\nwithin the dynamical mean field theory and the three-body scattering\napproximation, including a full calculation of the one-step photoemission\nprocess. From this comparison we conclude that although strong local many-body\nCoulomb interactions are of major importance for the qualitative description of\ncorrelation effects in Co, more sophisticated many-body calculations are needed\nin order to improve the quantitative agreement between theory and experiment,\nin particular concerning the linewidths. The quality of the overall agreement\nobtained for Co indicates that the effect of non-local correlations becomes\nweaker with increasing atomic number.",
        "positive": "Transport properties of dense deuterium-tritium plasmas: Consistent descriptions of the equation of states, and information about\ntransport coefficients of deuterium-tritium mixture are demonstrated through\nquantum molecular dynamic (QMD) simulations (up to a density of 600 g/cm$^{3}$\nand a temperature of $10^{4}$ eV). Diffusion coefficients and viscosity are\ncompared with one component plasma model in different regimes from the strong\ncoupled to the kinetic one. Electronic and radiative transport coefficients,\nwhich are compared with models currently used in hydrodynamic simulations of\ninertial confinement fusion, are evaluated up to 800 eV. The Lorentz number is\nalso discussed from the highly degenerate to the intermediate region."
    },
    {
        "anchor": "The Sub-bandgap Photoconductivity in InGaAs:ErAs Nanocomposites: The photoconductions of ultrafast InGaAs:ErAs nanocomposites at low\ntemperatures were investigated. The parabolic Tauc edge as well as the\nexponential Urbach tail are identified in the absorption spectrum. The Tauc\nedge supports that the density of states at the bottom of conduction band is\nproportional to the square root of energy. The Urbach edge is attributed to\ninterband transition caused by smooth microscopic internal fields. The square\nroot of mean-squared internal fields, whose distribution is Gaussian, is found\nin the order of $10^{5}$V/cm, agreeing very well with the theoretical\npredictions by Esser (B. ~ Esser, Phys. stat. sol. (b), vol. 51, 735 (1972)).",
        "positive": "Atomic Imaging of Mechanically Induced Topological Transition of\n  Ferroelectric Vortices: Ferroelectric vortices formed through complex lattice-charge interactions\nhave great potential in applications for future nanoelectronics such as\nmemories. For practical applications, it is crucial to manipulate these\ntopological states under external stimuli. Here, we apply mechanical loads to\nlocally manipulate the vortices in a PbTiO3-SrTiO3 superlattice via atomically\nresolved in situ scanning transmission electron microscopy. The vortices\nundergo a transition to the a-domain with in-plane polarization under external\ncompressive stress and spontaneously recover after removal of the stress. We\nreveal the detailed transition process at the atomic scale and reproduce this\nnumerically using phase-field simulations. These findings provide new pathways\nto control the exotic topological ferroelectric structures for future\nnanoelectronics and also valuable insights into understanding of lattice-charge\ninteractions at nanoscale."
    },
    {
        "anchor": "Birch's law at elevated temperatures: Birch's law in high pressure physics postulates a linear relationship between\nelastic wave speed and density and one of its most well known applications is\nin investigations into the composition of the inner core of the Earth using the\nPreliminary Reference Earth Model as the primary source of constraints.\nHowever, it has never been subjected to high precision tests even at moderately\nelevated temperatures. Here we carry out such a test by making use of the\nDensity Functional Theory of electronic structure calculation and the Density\nFunctional Perturbation Theory of calculating the phonon dispersion relation.\nWe show that a recently proposed modification to the Birch's law is\nconsistently satisfied more accurately than its original version. This modified\nversion states that it is the product of elastic wave speed and one-third power\nof density that should be a linear function of density. We have studied the\ncases of platinum, palladium, molybdenum and rhodium with cubic unit cell and\niron with hexagonal-close-packed unit cell with temperatures up to 1500K and\npressures up to about 360 GPa. We also examine the genericity of the validity\nof a recently proposed extension of the Birch's law according to which elastic\nwave speed is a linear function of temperature at a given density. Within the\nerror bars of our calculation, we find that this is consistent with our data\nfor the four cubic materials at temperatures up to 3300 K.",
        "positive": "Voltage deficit in solar cells with suppressed recombination: The observed open circuit voltages in best performing solar cells are\nexplained outside of the recombination paradigm, based on such factors as\nelectrostatic screening, Meyer-Neldel effect, and lateral nonuniformities. The\nunderlying concept of suppressed recombination presents a long neglected\nalternative pathway to efficient PV. The criterion of suppressed recombination\nis consistent with the data for best performing solar cells. Also, consistent\nwith the observations, is the open circuit voltage deficit that exhibits a\nlower bound of about $0.2-0.3$ V, does not correlate well with the optical gap,\nand shows a significant dispersion for materials possessing the same gap\nvalues."
    },
    {
        "anchor": "Effect of picosecond strain pulses on thin layers of the ferromagnetic\n  semiconductor (Ga,Mn)(As,P): The effect of picosecond acoustic strain pulses (ps-ASP) on a thin layer of\n(Ga,Mn)As co-doped with phosphorus was probed using magneto-optical Kerr effect\n(MOKE). A transient MOKE signal followed by low amplitude oscillations was\nevidenced, with a strong dependence on applied magnetic field, temperature and\nps-ASP amplitude. Careful interferometric measurement of the layer's thickness\nvariation induced by the ps-ASP allowed us to model very accurately the\nresulting signal, and interpret it as the strain modulated reflectivity\n(differing for $\\sigma_{\\pm}$ probe polarizations), independently from dynamic\nmagnetization effects.",
        "positive": "New Views of Crystal Symmetry: Already Hermann Grassmann's father Justus (1829, 1830) published two works on\nthe geometrical description of crystals, influenced by the earlier works of\nC.S. Weiss (1780-1856) on three main crystal forces governing crystal\nformation. In his 1840 essay on the derivation of crystal shapes from the\ngeneral law of crystal formation Hermann established the notion of a\nthree-dimensional vectorial system of forces with rational coefficients, that\nrepresent the interior crystal structure, regulate its formation, its shape and\nphysical behavior. In the Ausdehnungslehre 1844 (Paragraph 171) he finally\nwrites: I shall conclude this presentation by one of the most beautiful\napplications which can be made of the science treated, i.e. the application to\ncrystal figures (Scholz, 1996). The geometry of crystals thus certainly\ninfluenced the Ausdehnungslehre. In this paper we see how Grassmann's work\ninfluenced Clifford's creation of geometric algebras, which in turn leads to a\nnew geometric description of crystal symmetry suitable for modern computer\nalgebra graphics."
    },
    {
        "anchor": "Dynamic phase transition properties and hysteretic behavior of a\n  ferrimagnetic core-shell nanoparticle in the presence of a time dependent\n  magnetic field: We have presented dynamic phase transition features and stationary-state\nbehavior of a ferrimagnetic small nanoparticle system with a core-shell\nstructure. By means of detailed Monte Carlo simulations, a complete picture of\nthe phase diagrams and magnetization profiles have been presented and the\nconditions for the occurrence of a compensation point $T_{comp}$ in the system\nhave been investigated. According to N\\'{e}el nomenclature, the magnetization\ncurves of the particle have been found to obey P-type, N-type and Q-type\nclassification schemes under certain conditions. Much effort has been devoted\nto investigation of hysteretic response of the particle and we observed the\nexistence of triple hysteresis loop behavior which originates from the\nexistence of a weak ferromagnetic core coupling $J_{c}/J_{sh}$, as well as a\nstrong antiferromagnetic interface exchange interaction $J_{int}/J_{sh}$. Most\nof the calculations have been performed for a particle in the presence of\noscillating fields of very high frequencies and high amplitudes in comparison\nwith exchange interactions which resembles a magnetic system under the\ninfluence of ultrafast switching fields. Particular attention has also been\npaid on the influence of the particle size on the thermal and magnetic\nproperties, as well as magnetic features such as coercivity, remanence and\ncompensation temperature of the particle. We have found that in the presence of\nultrafast switching fields, the particle may exhibit a dynamic phase transition\nfrom paramagnetic to a dynamically ordered phase with increasing ferromagnetic\nshell thickness.",
        "positive": "Enabling photoemission electron microscopy in liquids via\n  graphene-capped microchannel arrays: Photoelectron emission microscopy PEEM is a powerful tool to\nspectroscopically image dynamic surface processes at the nanoscale but is\ntraditionally limited to ultra high or moderate vacuum conditions. Here, we\ndevelop a novel grapheme capped multichannel array sample platform that extends\nthe capabilities of photoelectron spectromicroscopy to routine liquid and\natmospheric pressure studies with standard PEEM setups. Using this platform, we\nshow that graphene has only a minor influence on the electronic structure of\nwater in the first few layers and thus will allow for the examination of\nminimally perturbed aqueous phase interfacial dynamics. Analogous to microarray\nscreening technology in biomedical research, our platform is highly suitable\nfor applications in tandem with large-scale data mining, pattern recognition,\nand combinatorial methods for spectro temporal and spatiotemporal analyses at\nsolid liquid interfaces. Using Bayesian linear unmixing algorithm, we were able\nto discriminate between different X-ray induced water radiolysis scenarios and\nobserve a metastable wetting intermediate water layer during the late stages of\nbubble formationformation"
    },
    {
        "anchor": "Electromechanical behavior of BaTiO3 from first principles: Using an effective Hamiltonian parametrized from first principles, Monte\nCarlo simulations are performed in order to study the piezoelectric response of\nBaTiO3 in the ferroelectric tetragonal phase as a function of temperature. The\neffect of an electric field on the phase behavior is also illustrated by a\nsimulation of the transformation of a rhombohedral domain into a tetragonal one\nunder a strong field.",
        "positive": "Finite-Temperature Atomic Structure of 180^o Ferroelectric Domain Walls\n  in PbTiO3: In this letter we obtain the finite-temperature structure of 180^o domain\nwalls in PbTiO3 using a quasi-harmonic lattice dynamics approach. We obtain the\ntemperature dependence of the atomic structure of domain walls from 0K up to\nroom temperature. We also show that both Pb-centered and Ti-centered 180^o\ndomain walls are thicker at room temperature; domain wall thickness at T=300K\nis about three times larger than that of T=0K. Our calculations show that\nTi-centered domain walls have a lower free energy than Pb-centered domain walls\nand hence are more likely to be seen at finite temperatures."
    },
    {
        "anchor": "Room Temperature Light-Mediated Long-Range Coupling of Excitons in\n  Perovskites: Perovskites have been the focus of attention due to their multitude of\noutstanding optoelectronic properties and structural versatility.\nTwo-dimensional halide perovskite such as (C_6H_5C_2H_4NH_3)_2PbI_4, or simply\nPEPI, forms natural multiple quantum wells with enhanced light-matter\ninteractions, making them attractive systems for further investigation. This\nwork reports tunable splitting of exciton modes in PEPI resulting from strong\nlight-matter interactions, manifested as multiple dips (modes) in the\nreflection spectra. While the origin of the redder mode is well understood,\nthat for the bluer dip at room temperature is still lacking. Here, it is\nrevealed that the presence of the multiple modes originates from an indirect\ncoupling between excitons in different quantum wells. The long-range\ncharacteristic of the mediated coupling between excitons in distant quantum\nwells is also demonstrated in a structure design along with its tunability.\nMoreover, a device architecture involving an end silver layer enhances the two\nexcitonic modes and provides further tunability. Importantly, this work will\nmotivate the possibility of coupling of the excitonic modes with a confined\nlight mode in a microcavity to produce multiple exciton-polariton modes.",
        "positive": "Evidence for superconductivity above 260 K in lanthanum superhydride at\n  megabar pressures: Recent predictions and experimental observations of high Tc superconductivity\nin hydrogen-rich materials at very high pressures are driving the search for\nsuperconductivity in the vicinity of room temperature. We have developed a\nnovel preparation technique that is optimally suited for megabar pressure\nsyntheses of superhydrides using pulsed laser heating while maintaining the\nintegrity of sample-probe contacts for electrical transport measurements to 200\nGPa. We detail the synthesis and characterization, including four-probe\nelectrical transport measurements, of lanthanum superhydride samples that\ndisplay a significant drop in resistivity on cooling beginning around 260 K and\npressures of 190 GPa. Additional measurements on two additional samples\nsynthesized the same way show resistance drops beginning as high as 280 K at\nthese pressures. The loss of resistance at these high temperatures is not\nobserved in control experiments on pure La as well as in partially transformed\nsamples at these pressures, and x-ray diffraction as a function of temperature\non the superhydride reveal no structural changes on cooling. We infer that the\nresistance drop is a signature of the predicted room-temperature\nsuperconductivity in LaH10, in good agreement with density functional structure\nsearch and BCS theory calculations."
    },
    {
        "anchor": "Magnetic and transport properties of Sb2Te3 doped with high\n  concentration of Cr: We report on molecular beam epitaxy and properties of a magnetic topological\ninsulator, Cr doped Sb2Te3. The composition analysis reveals that Cr replaces\nSb site, and x-ray diffraction confirms that single phase textured crystal\nstructure can be obtained for (CrxSb1-x)2Te3 with x up to 0.44. Further\nincrease in x results in phase separation or precipitates in the material. The\nCurie temperature TC increases with x up to 0.44, and reaches to 250 K, which\nis the highest TC observed till now in magnetically doped topological\ninsulators.",
        "positive": "Ab-initio calculation of the Hubbard $U$ and Hund exchange $J$ in local\n  moment magnets: The case of Mn-based full Heusler compounds: Mn-based full Heusler compounds possess well-defined local atomic Mn moments,\nand thus the correlation effects between localized d electrons are expected to\nplay an important role in determining the electronic and magnetic properties of\nthese materials. Employing ab-initio calculations in conjunction with the\nconstrained random-phase approximation (cRPA) method, we calculate the strength\nof the effective on-site Coulomb interaction parameters (Hubbard U and Hund\nexchange J) in the case of X2MnZ full Heusler compounds with X being one of Ni,\nPd or Cu, and Z being one of In, Sn, Sb or Te. We show that the Z element (or\nsp element) in Heusler compounds significantly reduces the strength of the\nHubbard U parameter for Mn 3d electrons compared to the elementary bulk Mn. On\nthe contrary, the effect of the sp-atom on the strength of the U parameter of\nNi, Cu or Pd valence d electrons is not so substantial with respect to the\nelementary bulk values. The U values for all transition metal atoms decrease\nwith increasing sp electron number in the In-Sn-Sb-Te sequence. Our cRPA\ncalculations reveal that despite their well-defined local magnetic moments, the\nMn-based full Heusler alloys fall into the category of the weakly correlated\nmaterials."
    },
    {
        "anchor": "Knot-isomers of Moebius Cyclacene: How Does the Number of Knots\n  Influence the Structure and First Hyperpolarizability?: Four large ring molecules composed by 15 nitrogen-substituted benzene rings,\nnamed as \"knot-isomers of Moebius cyclacene\", i.e. non-Moebius cyclacenes\nwithout a knot (0), Moebius cyclacenes with a knot (1), non-Moebius cyclacenes\nwith two knots (2), and Moebius cyclacenes with three knots (3), are\nsystematically studied for their structures and nonlinear optical properties.\nThe first hyperpolarizability (beta_0) values of these four knot-isomers\nstructures are 4693 (0) < 10484 (2) < 25419 (3) < 60846 au (1). The beta_0\nvalues (60846 for 1, 10484 for 2 and 25419 au for 3) of the knot-isomers with\nknot(s) are larger than that (4693 au for 0) of the knot-isomer without a knot.\nIt shows that the beta_0 value can be dramatically increases (13 times) by\nintroducing the knot(s) to the cyclacenes structures. It is found that\nintroducing knots to cyclacenes is a new means to enhance the first\nhyperpolarizability.",
        "positive": "High-performance descriptor for magnetic materials: Accurate\n  discrimination of magnetic structure: The magnetic structure is crucial in determining the physical properties\ninherent in magnetic compounds. We present an adequate descriptor for magnetic\nstructure with proper magnetic symmetry and high discrimination performance,\nwhich does not depend on artificial choices for coordinate origin, axis, and\nmagnetic unit cell in crystal. We extend the formalism called ``smooth overlap\nof atomic positions'' (SOAP), providing a numerical representation of atomic\nconfigurations to that of magnetic moment configurations. We introduce the\ndescriptor in terms of the vector spherical harmonics to describe a magnetic\nmoment configuration and partial spectra from the expansion coefficients. We\ndiscuss that the lowest-order partial spectrum is insufficient to discriminate\nthe magnetic structures with different magnetic anisotropy, and a higher-order\npartial spectrum is required in general to differentiate detailed magnetic\nstructures on the same atomic configuration. We then introduce the fourth-order\npartial spectrum and evaluate the discrimination performance for different\nmagnetic structures, mainly focusing on the difference in magnetic symmetry.\nThe modified partial spectra that are defined not to reflect the difference of\nmagnetic anisotropy are also useful in evaluating magnetic structures obtained\nfrom the first-principles calculations performed without spin-orbit coupling.\nWe apply the present method to the symmetry-classified magnetic structures for\nthe crystals of Mn$_3$Ir and Mn$_3$Sn, which are known to exhibit anomalous\ntransport under the antiferromagnetic order, and examine the discrimination\nperformance of the descriptor for different magnetic structures on the same\ncrystal."
    },
    {
        "anchor": "In situ quasi-elastic neutron scattering study on the water dynamics and\n  reaction mechanisms in alkali-activated slags: In this study, in situ quasi-elastic neutron scattering (QENS) has been\nemployed to probe the water dynamics and reaction mechanisms occurring during\nthe formation of NaOH- and Na2SiO3-activated slags, an important class of\nlow-CO2 cements, in conjunction with isothermal conduction calorimetry (ICC),\nFourier transform infrared spectroscopy (FTIR) analysis and N2 sorption\nmeasurements. We show that the single ICC reaction peak in the NaOH-activated\nslag is accompanied with a transformation of free water to bound water (from\nQENS analysis), which directly signals formation of a sodium-containing\naluminum-substituted calcium-silicate-hydrate (C-(N)-A-S-H) gel, as confirmed\nby FTIR. In contrast, the Na2SiO3-activated slag sample exhibits two distinct\nreaction peaks in the ICC data, where the first reaction peak is associated\nwith conversion of constrained water to bound and free water, and the second\npeak is accompanied with conversion of free water to bound and constrained\nwater (from QENS analysis). The second conversion is attributed to formation of\nthe main reaction product (i.e., C-(N)-A-S-H gel) as confirmed by FTIR and N2\nsorption data. Analysis of the QENS, FTIR and N2 sorption data together with\nthermodynamic information from the literature explicitly shows that the first\nreaction peak is associated with the formation of an initial gel (similar to\nC-(N)-A-S-H gel) that is governed by the Na+ ions and silicate species in\nNa2SiO3 solution and the dissolved Ca/Al species from slag. Hence, this study\nexemplifies the power of in situ QENS, when combined with laboratory-based\ncharacterization techniques, in elucidating the water dynamics and associated\nchemical mechanisms occurring in complex materials, and has provided important\nmechanistic insight on the early-age reactions occurring during formation of\ntwo alkali-activated slags.",
        "positive": "Substrate-tuning of correlated spin-orbit oxides: We have systematically investigated substrate-strain effects on the\nelectronic structures of two representative Sr-iridates, a correlated-insulator\nSr$_2$IrO$_4$ and a metal SrIrO$_3$. Optical conductivities obtained by the\n\\emph{ab initio} electronic structure calculations reveal that the tensile\nstrain shifts the optical peak positions to higher energy side with altered\nintensities, suggesting the enhancement of the electronic correlation and\nspin-orbit coupling (SOC) strength in Sr-iridates. The response of the\nelectronic structure upon tensile strain is found to be highly correlated with\nthe direction of magnetic moment, the octahedral connectivity, and the SOC\nstrength, which cooperatively determine the robustness of $J_{eff}$=1/2 ground\nstates. Optical responses are analyzed also with microscopic model calculation\nand compared with corresponding experiments. In the case of SrIrO$_3$, the\nevolution of the electronic structure near the Fermi level shows high\ntunability of hole bands, as suggested by previous experiments."
    },
    {
        "anchor": "Structural and magnetic characterization of the elusive Jahn-Teller\n  active NaCrF3: We report the structural and magnetic characterization of the elusive Jahn-\nTeller active compound NaCrF3.",
        "positive": "Why do nanowires grow with their c-axis vertically-aligned in the\n  absence of epitaxy?: Images of uniform and upright nanowires are fascinating, but often, they are\nquite puzzling, when epitaxial templating from the substrate is clearly absent.\nHere, we reveal the physics underlying one such hidden growth guidance\nmechanism through a specific example - the case of ZnO nanowires grown on\nsilicon oxide and glass. We show how electric fields exerted by the insulating\nsubstrate may be manipulated through the surface charge to define the\norientation and polarity of the nanowires. Surface charge is ubiquitous on the\nsurfaces of semiconductors and insulators, and as a result, substrate electric\nfields need always be considered. Our results suggest a new concept, according\nto which the growth of wurtzite semiconductors may often be described as a\nprocess of electric-charge-induced self assembly, wherein the internal built-in\nfield in the polar material tends to align in parallel to an external field\nexerted by the substrate to minimize the interfacial energy of the system."
    },
    {
        "anchor": "Multiphase strontium molybdate thin films for plasmonic local heating\n  applications: In the search for alternative plasmonic materials SrMoO3 has recently been\nidentified as possessing a number of desirable optical properties. Owing to the\nrequirement for many plasmonic devices to operate at elevated temperatures\nhowever, it is essential to characterize the degradation of these properties\nupon heating. Here, SrMoO3 thin films are annealed in air at temperatures\nranging from 75 - 500{\\deg} C. Characterizations by AFM, XRD, and spectroscopic\nellipsometry after each anneal identify a loss of metallic behaviour after\nannealing at 500{\\deg} C, together with the underlying mechanism. Moreover, it\nis shown that by annealing the films in nitrogen following deposition, an\nadditional crystalline phase of SrMoO4 is induced at the film surface, which\nsuppresses oxidation at elevated temperatures.",
        "positive": "Reaction-Diffusion Degradation Model for Delayed Erosion of Cross-Linked\n  Polyanhydride Biomaterials: We develop a theoretical model to explain the long induction interval of\nwater intake that precedes the onset of erosion due to degradation caused by\nhydrolysis in the recently synthesized and studied cross-linked polyanhydrides.\nVarious kinetic mechanisms are incorporated in the model in an attempt to\nexplain the experimental data for the mass loss profile. Our key finding is\nthat the observed long induction interval is attributable to the nonlinear\ndependence of the degradation rate constants on the local water concentration,\nwhich essentially amounts to the breakdown of the standard rate-equation\napproach, potential causes for which are then discussed. Our theoretical\nresults offer physical insights into which microscopic studies will be required\nto supplement the presently available macroscopic mass-loss data in order to\nfully understand the origin of the observed behavior."
    },
    {
        "anchor": "Strong Orientational Coordinates and Orientational Order Parameters For\n  Symmetric Objects: Recent advancements in the synthesis of anisotropic macromolecules and\nnanoparticles have spurred an immense interest in theoretical and computational\nstudies of self-assembly. The cornerstone of such studies is the role of shape\nin self-assembly and in inducing complex order. The problem of identifying\ndifferent types of order that can emerge in such systems can, however, be\nchallenging. Here, we revisit the problem of quantifying orientational order in\nsystems of building blocks with non-trivial rotational symmetries. We first\npropose a systematic way of constructing orientational coordinates for such\nsymmetric building blocks. We call the arising tensorial coordinates strong\norientational coordinates (SOCs) as they fully and exclusively specify the\norientation of a symmetric object. We then use SOCs to describe and quantify\nlocal and global orientational order, and spatiotemporal orientational\ncorrelations in systems of symmetric building blocks. The SOCs and the\norientational order parameters developed in this work are not only useful in\nperforming and analyzing computer simulations of symmetric molecules or\nparticles, but can also be utilized for the efficient storage of rotational\ninformation in long trajectories of evolving many-body systems.",
        "positive": "Giant optical anisotropy in cylindrical self-assembled InAs/GaAs quantum\n  rings: Using a single-particle atomistic pseudopotential method followed by a\nmany-particle configuration interaction method, we investigate the geometry,\nelectronic structure and optical transitions of a self-assembled InAs/GaAs\nquantum ring (QR), changing its shape continously from a lens-shaped quantum\ndot (QD) to a nearly one dimensional ring. We find that the biaxial strain in\nthe ring is strongly asymmetric in the plane perpendicular to the QR growth\ndirection, leading to giant optical anisotropy."
    },
    {
        "anchor": "Strong electron-phonon coupling and carrier self-trapping in Sb$_2$S$_3$: Antimony sulphide (Sb$_2$S$_3$) is an Earth-abundant and non-toxic material\nthat is under investigation for solar energy conversion applications. However,\nit still suffers from poor power conversion efficiency and a large open circuit\nvoltage loss that have usually been attributed to point or interfacial defects\nand trap states. More recently, a self-trapped exciton has been suggested as\nthe microscopic origin for the performance loss. By using first-principles\nmethods, we demonstrate that Sb$_2$S$_3$ exhibits strong electron-phonon\ncoupling, which results in a large renormalization of 200 meV of the absorption\nedge when temperature increases from 10K to 300K, and in a quasi-1D electron\npolaron that is delocalized in the ribbon direction of the crystal structure,\nbut localized in the inter-ribbon directions. The calculated polaron formation\nenergy of 67 meV agrees well with experimental measurements, suggesting that\nself-trapped excitons are likely to form with the mediation of an electron\npolaron. Our results demonstrate the importance of systematically investigating\nelectron-phonon coupling and polaron formation in the antimony chalcogenide\nfamily of semiconductors for optoelectronic applications.",
        "positive": "Gaussian approximation potentials for body-centered-cubic transition\n  metals: We develop a set of machine-learning interatomic potentials for elemental V,\nNb, Mo, Ta, and W using the Gaussian approximation potential framework. The\npotentials show good accuracy and transferability for elastic, thermal, liquid,\ndefect, and surface properties. All potentials are augmented with accurate\nrepulsive potentials, making them applicable to radiation damage simulations\ninvolving high-energy collisions. We study melting and liquid properties in\ndetail and use the potentials to provide melting curves up to 400 GPa for all\nfive elements."
    },
    {
        "anchor": "Structure, mechanical and thermodynamic stability of vacancy clusters in\n  Cu: The atomic structure, mechanical and thermodynamic stability of vacancy\nclusters in Cu are studied by atomistic simulations. The most stable atomic\nconfiguration of small vacancy clusters is determined. The mechanical stability\nof the vacancy clusters is examined by applying uniaxial and volumetric tensile\nstrain to the system. The yield stress and yield strain of the system are\nsignificantly reduced comparing to the prefect lattice. The dependence of\nvacancy formation and binding energy as a function of strain is explored and\ncan be understood from the liquid-drop model. We find that the formation energy\nof the vacancy clusters decreases monotonically as a function of the uniaxial\nstrain, while the formation energy increases first then decreases under the\nvolumetric tensile strain. The thermodynamic stability of the vacancy clusters\nis analyzed by calculating the Gibbs free binding energy and the total\nprobability of dissociation of the vacancy clusters at 300 K and 900 K under\nuniaxial and volumetric strains. We find that although most of the vacancy\nclusters appear to be thermodynamically stable, some of the immediate sized\nclusters have high probability of dissociation into smaller clusters.",
        "positive": "Solving the Kadanoff-Baym equations for inhomogenous systems:\n  Application to atoms and molecules: We have implemented time-propagation of the non-equilibrium Green function\nfor atoms and molecules, by solving the Kadanoff-Baym equations within a\nconserving self-energy approximation. We here demonstrate the usefulnes of\ntime-propagation for calculating spectral functions and for describing the\ncorrelated electron dynamics in a non-perturbative electric field. We also\ndemonstrate the use of time-propagation as a method for calculating\ncharge-neutral excitation energies, equivalent to highly advanced solutions of\nthe Bethe-Salpeter equation."
    },
    {
        "anchor": "Non-Abelian Topological Phases and Their Quotient Relations in Acoustic\n  Systems: Non-Abelian topological phases (NATPs) are highly sought-after candidate\nstates for quantum computing and communication while lacking straightforward\nconfiguration and manipulation, especially for classical waves. In this work,\nwe exploit novel braid-type couplings among a pair of triple-component acoustic\ndipoles, which act as functional elements with effective imaginary couplings.\nSequencing them in one dimension allows us to generate acoustic NATPs in a\ncompact yet reciprocal Hermitian system. We further provide the whole phase\ndiagram that encompasses all i, j, and k non-Abelian phases, and directly\ndemonstrate their unique quotient relations via different endpoint states. Our\nNATPs based on real-space braiding may inspire the exploration of acoustic\ndevices with non-commutative characters.",
        "positive": "Lindenmann Rule Applied to the Melting of Crystals and Ultrastable\n  Glasses: The ratio of the mean square amplitude root of thermal vibrations and the\ninteratomic distance is a universal constant dls at the melting temperature Tm.\nThe classical Gibbs free energy change completed by a volume energy saving els\n(or Delg)*DHm that governs the liquid to solid and liquid to ultra-stable glass\ntransformations leads to a universal constant equal to els (or Delg), DHm being\nthe crystal melting enthalpy. The minimum values 0.217 of els and 0.103 of dls\nare used to predict ultra-stable glass formation in pure metallic liquid\nelements at a universal reduced temperature 0g = (Tg-Tm)/Tm = -0.6223."
    },
    {
        "anchor": "Machine learning a general purpose interatomic potential for silicon: The success of first principles electronic structure calculation for\npredictive modeling in chemistry, solid state physics, and materials science is\nconstrained by the limitations on simulated length and time scales due to\ncomputational cost and its scaling. Techniques based on machine learning ideas\nfor interpolating the Born-Oppenheimer potential energy surface without\nexplicitly describing electrons have recently shown great promise, but\naccurately and efficiently fitting the physically relevant space of\nconfigurations has remained a challenging goal. Here we present a Gaussian\nApproximation Potential for silicon that achieves this milestone, accurately\nreproducing density functional theory reference results for a wide range of\nobservable properties, including crystal, liquid, and amorphous bulk phases, as\nwell as point, line, and plane defects. We demonstrate that this new potential\nenables calculations that would be extremely expensive with a first principles\nelectronic structure method, such as finite temperature phase boundary lines,\nself-diffusivity in the liquid, formation of the amorphous by slow quench, and\ndynamic brittle fracture. We show that the uncertainty quantification inherent\nto the Gaussian process regression framework gives a qualitative estimate of\nthe potential's accuracy for a given atomic configuration. The success of this\nmodel shows that it is indeed possible to create a useful\nmachine-learning-based interatomic potential that comprehensively describes a\nmaterial, and serves as a template for the development of such models in the\nfuture.",
        "positive": "Studies of the temperature and frequency dependent impedance of an\n  electroceramic functional oxide thermistor: The charge transport mechanism and the macroscopic dielectric constant in\npolycrystalline device materials commonly exhibit several components such as\nelectrode-sample interface, grain boundary and bulk contributions. In order to\ngain precise understanding of the functionality of polycrystalline\nelectroceramic device materials it is essential to deconvolute these\ncontributions. The paradigm of functional thermistor ceramics based on thick\nfilm spinel manganates has been studied by temperature dependent alternating\ncurrent impedance spectroscopy. Three typical relaxation phenomena were\ndetected, which all showed a separated temperature dependence of resistivity\nconsistent with thermally activated charge transport. The dominating grain\nboundary and the interface contributions exhibited distinctively different\ncapacitance allowing clear identification. The composite nature of the\ndielectric properties in polycrystalline functional ceramics was emphasized,\nand impedance spectroscopy was shown to be a powerful tool to account for and\nmodel such behaviour."
    },
    {
        "anchor": "Bright Fluorophores in the Second Near-Infrared Window: HgSe/CdSe\n  Quantum Dots: Fluorophores emitting in the NIR-IIb wavelength range (1.5 micron - 1.7\nmicron) show great potential for bioimaging due to their large tissue\npenetration. However, current fluorophores suffer from poor emission with\nquantum yields ~2% in aqueous solvents. In this work, we report the synthesis\nof HgSe/CdSe core/shell quantum dots emitting at 1.7 microns through the\ninterband transition. Growth of a thick shell led to a drastic increase in the\nphotoluminescence quantum yield, with a value of 55% in nonpolar solvents. The\nquantum yields of our QDs and other reported QDs are explained well by a model\nof Forster resonance energy transfer to ligands and solvent molecules. The\nmodel predicts a quantum yield >6% when these HgSe/CdSe QDs are solubilized in\nwater. Our work demonstrates the importance of a thick type-I shell to obtain\nbright emission in the NIR-IIb region",
        "positive": "Structural and Electrical Properties of MoTe$_2$ and MoSe$_2$ Grown by\n  Molecular Beam Epitaxy: We demonstrate the growth of thin films of molybdenum ditelluride and\nmolybdenum diselenide on sapphire substrates by molecular beam epitaxy. In-situ\nstructural and chemical analyses reveal stoichiometric layered film growth with\natomically smooth surface morphologies. Film growth along the (001) direction\nis confirmed by X-ray diffraction, and the crystalline nature of growth in the\n2H phase is evident from Raman spectroscopy. Transmission electron microscopy\nis used to confirm the layered film structure and hexagonal arrangement of\nsurface atoms. Temperature dependent electrical measurements show an insulating\nbehavior which agrees well with a two-dimensional variable-range hopping model,\nsuggesting that transport in these films is dominated by localized\ncharge-carrier states."
    },
    {
        "anchor": "Reducing electron beam damage through alternative STEM scanning\n  strategies. Part II -- Attempt towards an empirical model describing the\n  damage process: In this second part of a series we attempt to construct an empirical model\nthat can mimick all experimental observations made regarding the role of an\nalternative interleaved scan pattern in STEM imaging on the beam damage in a\nspecific zeolite sample. We make use of a 2D diffusion model that describes the\ndissipation of the deposited beam energy in the sequence of probe positions\nthat are visited during the scan pattern. The diffusion process allows for the\nconcept of trying to outrun the beam damage by carefully tuning the dwell time\nand distance between consecutively visited probe positions. We add a non linear\nfunction to include a threshold effect and evaluate the accumulated damage in\neach part of the image as a function of scan pattern details. Together, these\ningredients are able to describe qualitatively all aspects of the experimental\ndata and provide us with a model that could guide a further optimisation\ntowards even lower beam damage without lowering the applied electron dose. We\ndeliberately remain vague on what is diffusing here which avoids introducing\ntoo many sample specific details. This provides hope that the model can be\napplied also in sample classes that were not yet studied in such great detail\nby adjusting higher level parameters: a sample dependent diffusion constant and\ndamage threshold.",
        "positive": "Electric fields and substrates dramatically accelerate spin relaxation\n  in graphene: Electrons in graphene are theoretically expected to retain spin states much\nlonger than most materials, making graphene a promising platform for\nspintronics and quantum information technologies. Here, we use first-principles\ndensity-matrix (FPDM) dynamics simulations to show that interaction with\nelectric fields and substrates strongly enhance spin relaxation through\nscattering with phonons. Consequently, the relaxation time at room temperature\nreduces from microseconds in free-standing graphene to nanoseconds in graphene\non hexagonal boron nitride (hBN) substrate, the order of magnitude typically\nmeasured in experiments. Further, inversion symmetry breaking by hBN introduces\na stronger asymmetry in electron and hole spin lifetimes, than predicted by the\nconventional D'yakonov-Perel' (DP) model for spin relaxation. Deviations from\nthe conventional DP model are stronger for in-plane spin relaxation, resulting\nin out-of-plane to in-plane lifetime ratios much greater than 1/2 with a\nmaximum close to the Dirac point. These FPDM results, independent of\nsymmetry-specific assumptions or material-dependent parameters, also validate\nrecent modifications of the DP model to explain such deviations. Overall, our\nresults indicate that spin-phonon relaxation in the presence of substrates may\nbe more important in graphene than typically assumed, requiring consideration\nfor graphene-based spin technologies at room temperature."
    },
    {
        "anchor": "Symmetry-protected hierarchy of anomalous multipole topological band\n  gaps in nonsymmorphic metacrystals: Symmetry and topology are two fundamental aspects of many quantum states of\nmatter. Recently, new topological materials, higher-order topological\ninsulators, were discovered, featuring, e.g., bulk-edge-corner correspondence\nthat goes beyond the conventional topological paradigms. Here, we discover\nexperimentally that the nonsymmorphic $p4g$ acoustic metacrystals host a\nsymmetry-protected hierarchy of topological multipoles: the lowest band gap has\na quantized Wannier dipole and can mimic the quantum spin Hall effect, while\nthe second band gap exhibits quadrupole topology with anomalous Wannier bands.\nSuch a topological hierarchy allows us to observe experimentally distinct,\nmultiplexing topological phenomena and to reveal a topological transition\ntriggered by the geometry-transition from the $p4g$ group to the $C_{4v}$ group\nwhich demonstrates elegantly the fundamental interplay between symmetry and\ntopology. Our study demonstrates an instance that classical systems with\ncontrollable geometry can serve as powerful simulators for the discovery of\nnovel topological states of matter and their phase transitions.",
        "positive": "Interaction of oxygen interstitials with lattice faults in Ti: Oxygen greatly affects the mechanical properties of titanium. In addition,\ndislocations and twin boundaries influence the plastics deformation of hcp\nmetals. As part of a systematic study of defects interactions in Ti, we\ninvestigate the interactions of oxygen with (10-12) twin boundary and (10-10)\nprism plane stacking fault. The energetics of four interstitial sites in the\ntwin geometry are compared with the bulk octahedral site. We show that two of\nthese sites located at the twin boundary are more attractive to oxygen than\nbulk while the sites away from the boundary are repulsive. Moreover, we study\nthe interaction of oxygen with the prismatic stacking fault to approximate\noxygen-dislocation interaction. We show that oxygen increases the stacking\nfault energy and therefore is repelled by the faulted geometry and consequently\na dislocation core."
    },
    {
        "anchor": "Realistic inversion of diffraction data for an amorphous solid: the case\n  of amorphous silicon: We apply a new method \"force enhanced atomic refinement\" (FEAR) to create a\ncomputer model of amorphous silicon (a-Si), based upon the highly precise X-ray\ndiffraction experiments of Laaziri et al. The logic underlying our calculation\nis to estimate the structure of a real sample a-Si using experimental data and\nchemical information included in a non-biased way, starting from random\ncoordinates. The model is in close agreement with experiment and also sits at a\nsuitable minimum energy according to density functional calculations. In\nagreement with experiments, we find a small concentration of coordination\ndefects that we discuss, including their electronic consequences. The gap\nstates in the FEAR model are delocalized compared to a continuous random\nnetwork model. The method is more efficient and accurate, in the sense of\nfitting the diffraction data than conventional melt quench methods. We compute\nthe vibrational density of states and the specific heat, and find that both\ncompare favorably to experiments.",
        "positive": "Reply to 'Comment on \"Proper and improper chiral magnetic interactions\"\n  ': In our previous Letter [Phys. Rev. B 103, L140408 (2021)], we presented a\ndiscussion of the fundamental physical properties of the interactions\nparameterizing atomistic spin models in connection to first-principles\napproaches that enable their calculation for a given material. This explained\nhow some of those approaches can apparently lead to magnetic interactions that\ndo not comply with the expected physical properties, such as\nDzyaloshinskii-Moriya interactions which are non-chiral and independent of the\nspin-orbit interaction, and which we consequently termed `improper'. In the\npreceding Comment [Phys. Rev. B 105, 026401], the authors present arguments\nbased on the distinction between global and local approaches to the mapping of\nthe magnetic energy using first-principles calculations to support their\nproposed non-chiral Dzyaloshinskii-Moriya interactions and their dismissal of\nour distinction between `proper' and `improper' magnetic interactions. In this\nReply, we identify the missing step in the local approach to the mapping and\nexplain how ignoring this step leads to the identification of magnetic\ninteractions which do not comply with established physical principles and that\nwe have previously termed `improper'."
    },
    {
        "anchor": "Influence of the microstructure on the magnetism of Co-doped ZnO thin\n  films: The prediction of ferromagnetism at room temperature in Co-ZnO thin films has\ngenerated a large interest in the community due to the possible applications.\nHowever, the results are controversial, going from ferromagnetism to\nnon-ferromagnetism, leading to a large debate about its origin (secondary\nphase, Co clusters or not). By carefully studying the micro-structure of\nvarious Co-ZnO films, we show that the Co2+ partly substitutes the ZnO wurtzite\nmatrix without forming Co clusters. Surprisingly, the ferromagnetism nature of\nthe films disappears as the Co content increases. In addition, our results\nsuggest that the observed ferromagnetism is likely associated to a large amount\nof defects- close to the interface and strongly depending on the growth\ntemperature- which may explained the spreading of the results.",
        "positive": "Cohesion Energetics of Carbon Allotropes : Quantum Monte Carlo Study: We have performed quantum Monte Carlo calculations to study the cohesion\nenergetics of carbon allotropes, including $sp^3$-bonded diamond, $sp^2$-bonded\ngraphene, $sp$-$sp^2$ hybridized graphynes, and $sp$-bonded carbyne. The\ncomputed cohesive energies of diamond and graphene are found to be in excellent\nagreement with the corresponding values determined experimentally for diamond\nand graphite, respectively, when the zero-point energies, along with the\ninterlayer binding in the case of graphite, are included. We have also found\nthat the cohesive energy of graphyne decreases systematically as the ratio of\n$sp$-bonded carbon atoms increases. The cohesive energy of $\\gamma$-graphyne,\nthe most energetically-stable graphyne, turns out to be 6.766(6) eV/atom, which\nis smaller than that of graphene by 0.698(12) eV/atom. Experimental difficulty\nin synthesizing graphynes could be explained by their significantly smaller\ncohesive energies. Finally we conclude that the cohesive energy of a\nnewly-proposed graphyne can be accurately estimated with the carbon-carbon bond\nenergies determined from the cohesive energies of graphene and three different\ngraphynes considered here."
    },
    {
        "anchor": "Breakdown of the Born-Oppenheimer approximation in solid hydrogen and\n  hydrogen-rich solids: Hydrogen has been the subject of intense research following the discovery of\nhigh-temperature superconductivity in hydrides, and as a result of continuous\nefforts to produce solid hydrogen. The Born-Oppenheimer approximation is the\ncentral piece of the quantum mechanical description of molecules and solids and\nit is expected to have its weakest validity in hydrogen containing matter as it\nis the lightest element of all. The Born-Oppenheimer approximation is almost\nalways assumed in the description of solids. Some beyond Born-Oppenheimer\neffects are likely included in the state-of-art method used to describe\nhydrogen-rich materials, but the effects on the electronic structure in solids\nhave not been considered before. Here we compute the beyond Born-Oppenheimer\ncorrections to electron density and report a breakdown of the Born-Oppenheimer\napproximation in experimentally known hydride superconductor YH6 and in Cs-IV\nstructure of solid hydrogen. In both of these materials, we find a significant\ntransfer of electron density from the volumes surrounding the expected\npositions of the hydrogen nuclei to volumes in between the nuclei. We expect\nthese results to be the starting point of the beyond Born-Oppenheimer studies\nof electronic structure in solids, which is likely necessary to understand\nthese forms of hydrogen-containing materials, also having significant\ntechnological importance.",
        "positive": "Plasmonic electromagnetically-induced transparency in symmetric\n  structures: A broken symmetry is generally believed to be a prerequisite of plasmonic\nelectromagnetically-induced transparency (EIT), since the asymmetry renders the\nexcitation of the otherwise forbidden dark mode possible. Nevertheless,\naccording to the picture of magnetic-plasmon resonance (MPR) mediated plasmonic\nEIT, we show that the plasmonic EIT can be achieved even in the symmetric\nstructures based on the second-order MPR. This sharpens our understanding of\nthe existing concept, but also a profound insight into the plasmonic coherent\ninterference in the near-field zone."
    },
    {
        "anchor": "Crystal chemical insights on lead iodide perovskite doping from revised\n  effective radii of metal ions: Over the last few years of the heyday of hybrid halide perovskites, so many\nmetal cations additives have been tested to improve their optoelectronic\nproperties that it is already difficult to find an element that has not yet\nbeen tried. In general, the variety of these approaches is united under the\nname \"doping\", however, there is currently no clear understanding of the\nmechanisms of the influence of the metal ion additives on the properties of the\nlead halide perovskite materials. For many ions there is even no consensus on\nthe most fundamental questions: what lattice position does a given ion occupy\nand is it incorporated in the structure at all? Here, we derived a system of\neffective radii of different metal ions in the iodine environment for the set\nof iodide compounds and reveal their crystal chemical role in the APbI3\nperovskites. We analysed the possible lattice positions for 40 most common\nmonovalent, divalent, and trivalent metals to reveal whether they could\nsuccessfully enter into the perovskite structures. We show that, at most, three\nparameters - effective size, electronegativity and the softness of metal ions\nare the main ones for crystal chemical analysis of the possibility of metal\ndoping of hybrid halide perovskites. Our results provide a useful theoretical\nguidance to rationalize and improve current doping strategies of hybrid halide\nperovskites with metal ions.",
        "positive": "Kinetic Monte Carlo simulations of vacancy diffusion in non-dilute Ni-X\n  (X=Re,W,Ta) alloys: The mobility of vacancies in alloys may limit dislocation climb. Using a\ncombined density functional theory and kinetic Monte Carlo approach we\ninvestigate vacancy diffusion in Ni-Re, Ni-W, and Ni-Ta binary alloys up to 10\nat.% solute concentration. We introduce an interaction model that takes into\naccount the chemical environment close to the diffusing atom to capture the\neffect of solute-host and solute-solute interactions on the diffusion barriers.\nIn contrast to an ideal solid solution it is not only the diffusion barrier of\nthe solute atom that influences the vacancy mobility, but primarily the change\nin the host diffusion barriers due to the presence of solute atoms. This is\nevidenced by the fact that the observed vacancy slowdown as a function of\nsolute concentration is larger in Ni-W than in Ni-Re, even though Re is a\nslower diffuser than W. To model diffusion in complex, non-dilute alloys an\nexplicit treatment of interaction energies is thus unavoidable. In the context\nof Ni-based superalloys two conclusions can be drawn from our kinetic Monte\nCarlo simulations: the observed slowdown in vacancy mobility is not sufficient\nto be the sole cause for the so-called Re-effect; and assuming a direct\ncorrelation between vacancy mobility, dislocation climb, and creep strength the\nexperimentally observed similar effect of W and Re in enhancing creep strength\ncan be confirmed."
    },
    {
        "anchor": "Ab initio calculation of spin fluctuation spectra using time dependent\n  density functional perturbation theory, planewaves, and pseudopotentials: We present an implementation of time-dependent density functional\nperturbation theory for spin fluctuations, based on planewaves and\npseudopotentials. We compute the dynamic spin susceptibility self-consistently\nby solving the time-dependent Sternheimer equation, within the adiabatic local\ndensity approximation to the exchange and correlation kernel. We demonstrate\nour implementation by calculating the spin susceptibility of representative\nelemental transition metals, namely bcc Fe, fcc Ni and bcc Cr. The calculated\nmagnon dispersion relations of Fe and Ni are in agreement with previous work.\nThe calculated spin susceptibility of Cr exhibits a soft-paramagnon\ninstability, indicating the tendency of the Cr spins to condense in a\nincommensurate spin density wave phase, in agreement with experiment.",
        "positive": "Effects of Interference between Energy Absorption Processes of Molecule\n  and Surface Plasmons on Light Emission Induced by Scanning Tunneling\n  Microscopy: Effects of coupling between an molecular exciton and a surface plasmon\n(exciton-plasmon coupling) on the luminescence properties of the molecule and\nthe surface plasmons are investigated using nonequilibrium Green's function\nmethod. Molecular absorption and enhancement by molecular electronic and\nvibrational modes (molecular modes) lead to dip and peak structures in the\nluminescence spectra of the surface plasmons. The re-absorption by the surface\nplasmons leads to a dent structure in their luminescence spectra. It is found\nthat the processes of the molecular absorption and the re-absorption by the\nsurface plasmons interfere with each other. Enhancement and suppression of\nthese energy-absorption processes are due to the interference. Moreover, due to\nthe exciton-plasmon coupling, excitation channels of the molecule arise in the\nenergy range lower than the first electronic excitation energy of the molecule.\nIt is found that the electron transitions via these excitation channels give\nrise to the molecular luminescence and the vibrational excitations at the bias\nvoltage lower than the ratio of the first electronic excitation energy of the\nmolecule to the elementary charge. The results also indicate that the\nvibrational excitations assist the emission of photons, whose energy exceeds\nthe product of the elementary charge and the bias voltage (upconverted\nluminescence)."
    },
    {
        "anchor": "Chalcogenide Perovskites- an Emerging Class of Ionic Semiconductors: We report the synthesis and characterization of a novel class of ionic\nsemiconductor materials- inorganic chalcogenide perovskites. Several different\ncompounds including BaZrS3, CaZrS3, SrTiS3 and SrZrS3 were synthesized by high\ntemperature sulfurization of their oxide counterparts. Their crystal structures\nwere identified by XRD and composition by EDX. UV-vis and photoluminescence\nmeasurements confirmed that they are direct gap semiconductors with band gap\nvalues consistent with theoretical predictions. By adopting an anion alloying\napproach, we demonstrate widely tunable band gap from 1.73 eV to 2.87 eV. These\nstrongly ionic semiconductors provide a new avenue for engineering the\nsemiconducting properties for applications such as energy harvesting, solid\nstate lighting and sensing.",
        "positive": "Registration between DCT and EBSD datasets for multiphase\n  microstructures: The ability to characterise the three-dimensional microstructure of\nmultiphase materials is essential for understanding the interaction between\nphases and associated materials properties. Here, laboratory-based\ndiffraction-contrast tomography (DCT), a recently-established materials\ncharacterization technique that can determine grain phases, morphologies,\npositions and orientations in a voxel-based reconstruction method, was used to\nmap part of a dual-phase steel alloy sample. To assess the resulting\nmicrostructures that were produced by the DCT technique, an EBSD map was\ncollected within the same sample volume. To identify the 2D slice of the 3D DCT\nreconstruction that best corresponded to the EBSD map, a novel registration\ntechnique based solely on grain-averaged orientations was developed -- this\nregistration technique requires very little a priori knowledge of dataset\nalignment and can be extended to other techniques that only recover\ngrain-averaged orientation data such as far-field 3D X-ray diffraction\nmicroscopy. Once the corresponding 2D slice was identified in the DCT dataset,\ncomparisons of phase balance, grain size, shape and texture were performed\nbetween DCT and EBSD techniques. More complicated aspects of the\nmicrostructural morphology such as grain boundary shape and grains less than a\ncritical size were poorly reproduced by the DCT reconstruction, primarily due\nto the difference in resolutions of the technique compared with EBSD. However,\nlab-based DCT is shown to accurately determine the centre-of-mass position,\norientation, and size of the large grains for each phase present, austenite and\nmartensitic ferrite. The results reveals a complex ferrite grain network of\nsimilar crystal orientations that are absent from the EBSD dataset. Such detail\ndemonstrates that lab-based DCT, as a technique, shows great promise in the\nfield of multi-phase material characterization."
    },
    {
        "anchor": "Effects of surface compliance and relaxation on the frictional\n  properties of lamellar materials: We describe the results of atomic-level stick-slip friction measurements\nperformed on chemically-modified graphite, using atomic force microscopy (AFM).\nThrough detailed molecular dynamics simulations, coarse-grained simulations,\nand theoretical arguments, we report on complex indentation profiles during AFM\nscans involving local reversible exfoliation of the top layer of graphene from\nthe underlying graphite sample and its effect on the measured friction force\nduring retraction of the scanning tip. In particular, we report nearly constant\nlateral stick-slip magnitudes at decreasing loads, which cannot be explained\nwithin the standard framework based on continuum mechanics models for the\ncontact area. We explain this anomalous behavior by introducing the effect of\nlocal compliance of the topmost graphene layer, which varies when interaction\nwith the AFM tip is enhanced. Such behavior is not observed for non-lamellar\nmaterials. We extend our discussion toward the more general understanding of\nthe effects of the top layer relaxation on the friction force under pushing and\npulling loads. Our results may provide a more comprehensive understanding of\nthe effectively negative coefficient of friction recently observed on\nchemically-modified graphite.",
        "positive": "In-plane magnetic domains and N\u00e9el-like domain walls in thin flakes of\n  the room temperature CrTe$_2$ van der Waals ferromagnet: The recent discovery of magnetic van der Waals materials has triggered a\nwealth of investigations in materials science, and now offers genuinely new\nprospects for both fundamental and applied research. Although the catalogue of\nvan der Waals ferromagnets is rapidly expanding, most of them have a Curie\ntemperature below 300 K, a notable disadvantage for potential applications.\nCombining element-selective x-ray magnetic imaging and magnetic force\nmicroscopy, we resolve at room temperature the magnetic domains and domains\nwalls in micron-sized flakes of the CrTe$_2$ van der Waals ferromagnet.\nFlux-closure magnetic patterns suggesting in-plane six-fold symmetry are\nobserved. Upon annealing the material above its Curie point (315 K), the\nmagnetic domains disappear. By cooling back down the sample, a different\nmagnetic domain distribution is obtained, indicating material stability and\nlack of magnetic memory upon thermal cycling. The domain walls presumably have\nN\\'eel texture, are preferentially oriented along directions separated by 120\ndegrees, and have a width of several tens of nanometers. Besides microscopic\nmapping of magnetic domains and domain walls, the coercivity of the material is\nfound to be of a few mT only, showing that the CrTe$_2$ compound is\nmagnetically soft. The coercivity is found to increase as the volume of the\nmaterial decreases."
    },
    {
        "anchor": "Model for computing kinetics of the graphene edge epitaxial growth on\n  copper: A basic kinetic model that incorporates a coupled dynamics of the carbon\natoms and dimers on a copper surface is used to compute growth of a\nsingle-layer graphene island. The speed of the island's edge advancement on\nCu[111] and Cu[100] surfaces is computed as a function of the growth\ntemperature and pressure. Spatially resolved concentration profiles of the\natoms and dimers are determined, and the contributions provided by these\nspecies to the growth speed are discussed. Island growth in the conditions of a\nthermal cycling is studied.",
        "positive": "Optically probing the fine structure of a single Mn atom in an InAs\n  quantum dot: We report on the optical spectroscopy of a single InAs/GaAs quantum dot (QD)\ndoped with a single Mn atom in a longitudinal magnetic field of a few Tesla.\nOur findings show that the Mn impurity is a neutral acceptor state A^0 whose\neffective spin J=1 is significantly perturbed by the QD potential and its\nassociated strain field. The spin interaction with photo-carriers injected in\nthe quantum dot is shown to be ferromagnetic for holes, with an effective\ncoupling constant of a few hundreds of micro-eV, but vanishingly small for\nelectrons."
    },
    {
        "anchor": "Tailoring Magnetic Doping in the Topological Insulator Bi2Se3: We theoretically investigate the possibility of establishing ferromagnetism\nin the topological insulator Bi2Se3 via magnetic doping of 3d transition metal\nelements. The formation energies, charge states, band structures, and magnetic\nproperties of doped Bi2Se3 are studied using first-principles calculations\nwithin density functional theory. Our results show that Bi substitutional sites\nare energetically more favorable than interstitial sites for single impurities.\nDetailed electronic structure analysis reveals that Cr and Fe doped materials\nare still insulating in the bulk but the intrinsic band gap of Bi2Se3 is\nsubstantially reduced due to the strong hybridization between the d states of\nthe dopants and the p states of the neighboring Se atoms. The calculated\nmagnetic coupling suggests that Cr doped Bi2Se3 is possible to be both\nferromagnetic and insulating, while Fe doped Bi2Se3 tends to be weakly\nantiferromagnetic.",
        "positive": "Anisotropic thermal expansion and thermomechanic properties of monolayer\n  $\u03b2$-Te: Recently, $\\beta$-Te (atomically 2D tellurium) with rectangular crystal\nstructure has been synthesized successfully on highly oriented pyrolytic\ngraphite substrates by using molecular beam epitaxy. It has been found\npossessing remarkable properties such as ultralow lattice thermal conductivity\nand high thermoelectric efficiency. Based on the first-principles calculations,\nwe study the thermal expansion and thermomechanic properties of the\nexperimental phase monolayer $\\beta$-Te, using quasiharmonic approach. It is\nfound $\\beta$-Te shows large positive thermal expansion at elevated\ntemperature, while the linear thermal expansion coefficient is negative along a\ndirection at very low temperature. The linear thermal expansion coefficient\nalong b direction is 4.9*10$^{-5}$ K$^{-1}$ at 500 K, which is considerably\nlarge in 2D materials. $\\beta$-Te exhibits strong in-plane anisotropy,\nincluding thermal expansion, 2D elastic moduli and Poisson's ratios. However,\nthe elastic moduli, Poisson's ratios and the in-plane anisotropy are weakened\nwith increasing temperature, and the variations are dominated by the\ngeneralized mode Gr\\\"{u}neisen parameters."
    },
    {
        "anchor": "Reinventing atomistic magnetic simulations with spin-orbit coupling: We propose a powerful extension to combined molecular and spin dynamics that\nfully captures the coupling between the atomic and spin subsystems via\nspin-orbit interactions. Its foundation is the inclusion of the local magnetic\nanisotropies that arise as a consequence of the lattice symmetry breaking due\nto phonons or defects. We demonstrate that our extension enables the exchange\nof angular momentum between the atomic and spin subsystems, which is critical\nto the challenges arising in the study of fluctuations and non-equilibrium\nprocesses in complex, natural, and engineered magnetic materials.",
        "positive": "A single-projection three-dimensional reconstruction algorithm for\n  scanning transmission electron microscopy data: Increasing interest in three-dimensional nanostructures adds impetus to\nelectron microscopy techniques capable of imaging at or below the nanoscale in\nthree dimensions. We present a reconstruction algorithm that takes as input a\nfocal series of four-dimensional scanning transmission electron microscopy\n(4D-STEM) data. We apply the approach to a lead iridate, Pb$_2$Ir$_2$O$_7$, and\nyttrium-stabilized zirconia,Y$_{0.095}$Zr$_{0.905}$O$_2$ , heterostructure from\ndata acquired with the specimen in a single plan-view orientation, with the\nepitaxial layers stacked along the beam direction. We demonstrate that Pb-Ir\natomic columns are visible in the uppermost layers of the reconstructed volume.\nWe compare this approach to the alternative techniques of depth sectioning\nusing differential phase contrast scanning transmission electron microscopy\n(DPC-STEM) and multislice ptychographic reconstruction."
    },
    {
        "anchor": "A Framework for Computing Transport Properties of Carbon Nanotube-based\n  Conductance Biochemical Sensors: In this paper we present a framework for fast quantum conductance\ncalculations of carbon nanotube-based sensing devices targeting aromatic amino\nacids within a tight binding approximation. The method begins by a novel\nparameterization procedure based on isospectral matrix flows. With the properly\nparameterized Hamiltonian we employ a linearly scaling algorithm to compute the\nquantum conductance in the coherent transport regime. A few conclusions are\npresented regarding the suitability of carbon nanotubes in aromatic amino acid\ndetection.",
        "positive": "Theory of Nonlinear Response for Charge and Spin Currents: The nonlinear Hall effect, which is the second-order harmonic charge Hall\neffect from the Berry curvature dipole in momentum space, has received much\nattention recently. As the responses to higher harmonics of the driving ac\nelectric field are prominent and measurable, we develop a general nonlinear\ntheory by taking the charge and spin currents as well as the longitudinal and\ntransverse effects into account. We introduce the expansion order of the\nelectric field and Berry curvature multipole moment, where the Berry curvature\ndipole is a particular one manifesting itself at the second harmonic order and\nthe second expansion order of the electric field. There are four cases with\nconserving or breaking the time-reversal symmetry (TRS) and inversion symmetry\n(IS). We find a specific ``selection rule\" that only longitudinal odd harmonic\norder charge currents exist for conserving both the TRS and IS, and with\nbreaking both symmetries, all harmonic order charge and spin currents are\nnonzero. With conserving TRS and breaking IS, the charge Hall current exists at\neven harmonic order, and the longitudinal charge current occurs at odd harmonic\norder. Only the longitudinal spin current survives at even harmonic order. With\nbreaking TRS and conserving IS, only odd harmonic order charge and spin\ncurrents can appear. Moreover, we observe that every harmonic order current\ncontains a series of infinite-order expansion of the electric field. We further\nshow that the Berry curvature dipole and quadrupole can be determined by\nmeasuring the second and fourth harmonic order currents in experiments. This\nmay open a way to explore the higher responses of an ac driving system."
    },
    {
        "anchor": "New zero Poisson's ratio models: Most materials exhibit positive Poisson's ratio (PR) values but special\nstructures can also present negative and, even rarer, zero (or close to zero)\nPR. Null PR structures have received much attention due to their unusual\nproperties and potential applications in different fields, such as aeronautics\nand bio-engineering. Here, we present a new and simple near-zero PR 2D\ntopological model based on a structural block composed of two smooth and rigid\nbars connected by a soft membrane or spring. It is not based on re-entrant or\nhoneycomb-like configurations, which have been the basis of many null or\nquasi-null PR models. Our topological model was 3D printed and the\nexperimentally obtained PR was$-0.003\\,\\pm 0.001\\,$, which is one the closest\nto zero value ever reported. This topological model can be easily extended to\n3D systems and with compression in any direction. The advantages and\ndisadvantages of these models are also addressed.",
        "positive": "Localized Magnetic States of Fe, Co, and Ni Impurities on Alkali Metal\n  Films: X-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism\n(XMCD) have been used to study transition metal impurities on K and Na films.\nThe multiplet structure of the XAS spectra indicates that Fe, Co, and Ni have\nlocalized atomic ground states with predominantly d7, d8, and d9 character,\nrespectively. XMCD shows that the localized impurity states possess large,\natomiclike, magnetic orbital moments that are progressively quenched as\nclusters are formed. Ni impurities on Na films are found to be nonmagnetic,\nwith a strongly increased d10 character of the impurity state. The results show\nthat the high magnetic moments of transition metals in alkali hosts originate\nfrom electron localization."
    },
    {
        "anchor": "Electron-phonon interaction and transport properties of metallic bulk\n  and monolayer transition metal dichalcogenide TaS$_2$: Transition metal dichalcogenides have recently emerged as promising\ntwo-dimensional materials with intriguing electronic properties. Existing\ncalculations of intrinsic phonon-limited electronic transport so far have\nconcentrated on the semicondcucting members of this family. In this paper we\nextend these studies by investigating the influence of electron-phonon coupling\non the electronic transport properties and band renormalization of prototype\ninherent metallic bulk and monolayer TaS$_2$. Based on density functional\nperturbation theory and semi-classical Boltzmann transport calculations,\npromising room temperature mobilities and sheet conductances are found, which\ncan compete with other established 2D materials, leaving TaS$_2$ as promising\nmaterial candidate for transparent conductors or as atomically thin\ninterconnects. Throughout the paper, the electronic and transport properties of\nTaS$_2$ are compared to those of its isoelectronic counterpart TaSe$_2$ and\nadditional informations to the latter are given. We furthermore comment on the\nconventional su- perconductivity in TaS$_2$, where no phonon-mediated\nenhancement of TC in the monolayer compared to the bulk state was found.",
        "positive": "Auger-mediated radiative recombination in three-dimensional\n  silicon/silicon-germanium nanostructures: In a semiconductor heterostructure with type II energy band alignment, the\nspatial separation between electrons and holes slows down their radiative\nrecombination. With increasing excitation intensity, Auger recombination\nquickly becomes the dominate recombination channel, and it produces carrier\nejection from the quantum well. Here, we show that in Si/SiGe three-dimensional\nnanostructures, this efficient process facilitates the formation of an\nelectron-hole plasma (EHP) and/or electron-hole droplets (EHDs) in thin Si\nbarriers separating SiGe clusters. In contrast to conventional, strongly\ntemperature dependent and slow radiative carrier recombination in bulk Si, this\nEHD/EHP luminescence in nanometer-thick Si layers is found to be nearly\ntemperature independent with radiative lifetime approaching 10^-8 s, which is\nonly slightly slower than that found in direct band gap III-V semiconductors."
    },
    {
        "anchor": "Generation of Anisotropic Massless Dirac Fermions and Asymmetric Klein\n  Tunneling in Few-Layer Black Phosphorus Superlattices: Artificial lattices have been employed in many two-dimensional systems,\nincluding those of electrons, atoms and photons, in a quest for massless Dirac\nparticles with flexibility and controllability. Periodically patterned molecule\nassembly and electrostatic gating as well as moir\\'e pattern induced by\nsubstrate, have produced electronic states with linear dispersions from\nisotropic two-dimensional electron gas (2DEG). Here we demonstrate that\nmassless Dirac fermions with tunable anisotropic characteristics can, in\ngeneral, be generated in highly anisotropic 2DEG under slowly varying external\nperiodic potentials. For patterned few-layer black phosphorus superlattices,\nthe new chiral quasiparticles exist exclusively in an isolated energy window\nand inherit the strong anisotropic properties of pristine black phosphorus.\nThese states exhibit asymmetric Klein tunneling with the direction of incidence\nfor wave packet with perfect transmission deviating from normal incidence by\nmore than 50{\\deg} under an appropriate barrier orientation.",
        "positive": "Dirac Cone Protected by Non-Symmorphic Symmetry and 3D Dirac Line Node\n  in ZrSiS: Materials harboring exotic quasiparticles, such as Dirac and Weyl\nfermions\\cite{xu2015discovery,borisenko2015time,weng2015weyl,xu2015observation},\nhave garnered much attention from the physics and material science communities.\nThese fermions are massless and, in some materials, have shown exceptional\nphysical properties such as ultrahigh mobility and extremely large\nmagnetoresistances\n\\cite{liang2015ultrahigh,ali2014large,du2015unsaturated,shekhar2015large}.\nRecently, new materials have been predicted to exist which exhibit line nodes\nof Dirac cones\n\\cite{PhysRevLett.115.036806,xie2015new,burkov2011topological,rhim2015landau}.\nHere, we show with angle resolved photoemission studies supported by \\textit{ab\ninitio} calculations that the highly stable, non-toxic and earth-abundant\nmaterial, ZrSiS, has an electronic band structure that hosts several Dirac\ncones which form a Fermi surface with a diamond-shaped line of Dirac nodes. We\nalso experimentally show, for the first time, that the square Si lattice in\nZrSiS is an excellent template for realizing the new types of 2D Dirac cones\nrecently predicted by Young and Kane \\cite{young2015dirac} and image an\nunforseen surface state that arises close to the 2D Dirac cone. Finally, we\nfind that the energy range of the linearly dispersed bands is as high as 2\\,eV\nabove and below the Fermi level; much larger than of any known Dirac material\nso far. This makes ZrSiS a very promising candidate to study the exotic\nbehavior of Dirac electrons, or Weyl fermions if a magnetic field is applied,\nas well as the properties of lines of Dirac nodes"
    },
    {
        "anchor": "Clarifying the definition of 'transonic' screw dislocations: A number of recent Molecular Dynamics (MD) simulations have demonstrated that\nscrew dislocations in face centered cubic (fcc) metals can achieve stable\nsteady state motion above the lowest shear wave speed ($v_\\text{shear}$) which\nis parallel to their direction of motion (often referred to as transonic\nmotion). This is in direct contrast to classical continuum analyses which\npredict a divergence in the elastic energy of the host material at a crystal\ngeometry dependent `critical' velocity $v_\\text{crit}$. Within this work, we\nfirst demonstrate through analytic analyses that the elastic energy of the host\nmaterial diverges at a dislocation velocity ($v_\\text{crit}$) which is greater\nthan $v_\\text{shear}$, i.e. $v_\\text{crit} > v_\\text{shear}$. We argue that it\nis this latter derived velocity ($v_\\text{crit}$) which separates `subsonic'\nand `supersonic' regimes of dislocation motion in the analytic solution.\n  In addition to our analyses, we also present a comprehensive suite of MD\nsimulation results of steady state screw dislocation motion for a range of\nstresses and several cubic metals at both cryogenic and room temperatures. At\nroom temperature, both our independent MD simulations and the earlier works\nfind stable screw dislocation motion only below our derived $v_\\text{crit}$.\nNonetheless, in real-world polycrystalline materials $v_\\text{crit}$ cannot be\ninterpreted as a hard limit for subsonic dislocation motion. In fact, at very\nlow temperatures our MD simulations of Cu at 10 Kelvin confirm a recent claim\nin the literature that true `supersonic' screw dislocations with dislocation\nvelocities $v>v_\\text{crit}$ are possible at very low temperatures.",
        "positive": "Precisely computing phonons via irreducible derivatives: Computing phonons from first-principles is typically considered a solved\nproblem, yet inadequacies in existing techniques continue to yield deficient\nresults in systems with sensitive phonons. Here we circumvent this issue using\nthe lone irreducible derivative (LID) and bundled irreducible derivative (BID)\napproaches to computing phonons via finite displacements, where the former\noptimizes precision via energy derivatives and the latter provides the most\nefficient algorithm using force derivatives. A condition number optimized (CNO)\nbasis for BID is derived which guarantees the minimum amplification of error.\nAdditionally, a hybrid LID-BID approach is formulated, where select irreducible\nderivatives computed using LID replace BID results. We illustrate our approach\non two prototypical systems with sensitive phonons: the shape memory alloy AuZn\nand metallic lithium. Comparing our resulting phonons in the aforementioned\ncrystals to calculations in the literature reveals nontrivial inaccuracies. Our\napproaches can be fully automated, making them well suited for both niche\nsystems of interest and high throughput approaches."
    },
    {
        "anchor": "Bipolar Charge Transport in Poly(3-hexyl thiophene)/Methanofullerene\n  Blends: A Ratio Dependent Study: We investigated the charge carrier mobility in pristine poly(3-hexyl\nthiophene-2,5-diyl) (P3HT):[6,6]-phenyl-C61 butyric acid methyl ester (PCBM)\nblend devices by applying the time resolved photoconductivity experiment in\ndependence on the donor:acceptor ratio. We observe a bipolar transport in all\nstudied samples ranging from pure polymer to polymer:fullerene with 90% PCBM\ncontent. For the ratios P3HT:PCBM 1:4 and 1:1 we observe two transit times in\nthe electron current transients, as well as hole double transients for\nP3HT:PCBM 1:2. We find high hole and electron mobilities in the order of\n10^(-3) - 10^(-2) cm^2/Vs for a concentration of 90% PCBM in the blend.",
        "positive": "Charge-stripe order in the electronic ferroelectric LuFe2O4: The structural features of the charge ordering states in LuFe2O4 are\ncharacterized by in-situ cooling TEM observations from 300K down to 20K. Two\ndistinctive structural modulations, a major q1= (1/3, 1/3, 2) and a weak\nq2=q1/10 + (0, 0, 3/2), have been well determined at the temperature of 20K.\nSystematic analysis demonstrates that the charges at low temperatures are well\ncrystallized in a charge stripe phase, in which the charge density wave\nbehaviors in a non-sinusoidal fashion resulting in elemental electric dipoles\nfor ferroelectricity. It is also noted that the charge ordering and\nferroelectric domains often change markedly with lowering temperatures and\nyields a rich variety of structural phenomena."
    },
    {
        "anchor": "Stability of Mn2RuxGa-based Multilayer Stacks: Perpendicular heterostructures based on a ferrimagnetic Mn2RuxGa (MRG) layer\nand a ferromagnetic Co/Pt multilayer were examined to understand the effects of\ndifferent spacer layers (V, Mo, Hf, HfOx and TiN) on the interfaces with the\nmagnetic electrodes, after annealing at 350 C. Loss of perpendicular anisotropy\nin MRG is strongly correlated with a reduction in the substrate-induced\ntetragonality due to relaxation of the crystal structure. In the absence of\ndiffusion, strain and chemical ordering within MRG are correlated. The limited\nsolubility of both Hf and Mo in MRG is a source of additional valence\nelectrons, which results in an increase in compensation temperature Tcomp. This\nalso stabilises perpendicular anisotropy, compensating for changes in strain\nand defect density. The reduction in squareness of the MRG hysteresis loop\nmeasured by anomalous Hall effect is <10 %, making it useful in active devices.\nFurthermore, a CoPt3 phase with (2 2 0) texture in the perpendicular Co/Pt free\nlayer promoted by a Mo spacer layer is the only one that retains its\nperpendicular anisotropy on annealing.",
        "positive": "Resonant inelastic x-ray scattering in warm-dense Fe compounds beyond\n  the SASE FEL resolution limit: Resonant inelastic x-ray scattering (RIXS) is a widely used spectroscopic\ntechnique, providing access to the electronic structure and dynamics of atoms,\nmolecules, and solids. However, RIXS requires a narrow bandwidth x-ray probe to\nachieve high spectral resolution. The challenges in delivering an energetic\nmonochromated beam from an x-ray free electron laser (XFEL) thus limit its use\nin few-shot experiments, including for the study of high energy density\nsystems. Here we demonstrate that by correlating the measurements of the\nself-amplified spontaneous emission (SASE) spectrum of an XFEL with the RIXS\nsignal, using a dynamic kernel deconvolution with a neural surrogate, we can\nachieve electronic structure resolutions substantially higher than those\nnormally afforded by the bandwidth of the incoming x-ray beam. We further show\nhow this technique allows us to discriminate between the valence structures of\nFe and Fe$_2$O$_3$, and provides access to temperature measurements as well as\nM-shell binding energies estimates in warm-dense Fe compounds."
    },
    {
        "anchor": "Effect of interface on mid-infrared photothermal response of MoS2 thin\n  film grown by pulsed laser deposition: Here we report mid infrared (mid-IR) photothermal response of multi layer\nMoS2 thin film grown on crystalline (p-type silicon and c-axis oriented single\ncrystal sapphire) and amorphous substrates (Si/SiO2 and Si/SiN) by pulsed laser\ndeposition (PLD) technique. The photothermal response of the MoS2 films was\nmeasured as changes in the resistance of MoS2 films when irradiated with mid IR\n(7 to 8.2 {\\mu}m) source. We show that it is possible to enhance the\ntemperature coefficient of resistance (TCR) of the MoS2 thin film by\ncontrolling the interface through proper choice of substrate and growth\nconditions. The thin films grown by PLD were characterized using XRD, Raman,\nAFM, XPS and TEM. High-resolution transmission electron microscopy (HRTEM)\nimages show that the MoS2 films grow on sapphire substrate in a layer-by-layer\nmanner with misfit dislocations. Layer growth morphology is disrupted when\ngrown on substrates with diamond cubic structure such as silicon due to growth\ntwin formation. The growth morphology is very different on amorphous substrates\nsuch as Si/SiO2 or Si/SiN. The MoS2 film grown on silicon shows a very high TCR\n(-2.9% K-1), mid IR sensitivity (delR/R=5.2 %) and responsivity (8.7 V/W) as\ncompared to films on other substrates.",
        "positive": "High-temperature neutron diffraction and first-principles study of\n  temperature-dependent crystal structures and atomic vibrations in Ti3AlC2,\n  Ti2AlC, and Ti5Al2C3: Herein we report on the thermal expansions and temperature-dependent crystal\nstructures of select ternary carbide MAX phases in the Ti-Al-C phase diagram in\nthe 100-1000 deg C temperature range. A bulk sample containing 38 wt.%\nTi5Al2C3, \"523\"), $32 wt.% Ti2AlC (\"211\"), 18 wt.% Ti3AlC2 (\"312\"), and 12 wt.%\n(Ti{0.5}Al{0.5})Al is studied by Rietveld analysis of high-temperature neutron\ndiffraction data. We also report on the same for a single-phase sample of\nTi$_3$AlC$_2$ for comparison. The thermal expansions of all the MAX phases\nstudied are higher in the $c$ direction than in the $a$ direction. The bulk\nexpansion coefficients - 9.3 x 10^-6 for Ti5Al2C3, 9.2 x 10^-6 for Ti2AlC, and\n9.0 x 10^-6 for Ti3AlC2 - are comparable within one standard deviation of each\nother. In Ti5Al2C3, the dimensions of the Ti-C octahedra for the 211-like and\n312-like regions are comparable to the Ti-C octahedra in Ti2AlC and Ti3AlC2,\nrespectively. The isotropic mean-squared atomic displacement parameters are\nhighest for the Al atoms in all three phases, and the values predicted from\nfirst-principles phonon calculations agree well with those measured."
    },
    {
        "anchor": "Computational engineering of sublattice ordering in a hexagonal\n  AlHfScTiZr high entropy alloy: Multi-principle element alloys have enormous potential, but their exploration\nsuffers from the tremendously large range of configurations. In the last decade\nsuch alloys have been designed with a focus on random solid solutions. Here we\napply an experimentally verified, combined thermodynamic and first-principles\ndesign strategy to reverse the traditional approach and to generate a new type\nof hcp Al-Hf-Sc-Ti-Zr high entropy alloy with a hitherto unique structure. A\nphase diagram analysis narrows down the large compositional space to a\nwell-defined set of candidates. First-principles calculations demonstrate the\nenergetic preference of an ordered superstructure over the competing disordered\nsolid solutions. The chief ingredient is the Al concentration, which can be\ntuned to achieve a D019 ordering of the hexagonal lattice. The computationally\ndesigned D019 superstructure is experimentally confirmed by transmission\nelectron microscopy and X-ray studies. Our scheme enables the exploration of a\nnew class of high entropy alloys.",
        "positive": "Hybrid Nodal-chain Semimetal State in MgCaN2: The distinct over-tilting of band crossings in topological semimetal\ngenerates the type-I and typeII classification of Dirac/Weyl and nodal-line\nfermions, accompanied by the exotic electronic and magnetic transport\nproperties. In this work, we propose a concept of hybrid nodal-chain semimetal,\nwhich is identified by the linked type-I and type-II nodal rings in the\nBrillouin zone. Based on first-principles calculations and swarm-intelligence\nstructure search technique, a new ternary nitride MgCaN2 crystal is proposed as\nthe first candidate to realize a novel 3D hybrid nodal-chain state. Remarkably,\na flat band is emergent as a characteristic signature of such a hybrid\nnodal-chain along certain direction in the momentum space, thereby serving a\nplatform to explore the interplay between topological semimetal state and flat\nband. Moreover, the underlying protection mechanism of the hybrid nodal-chain\nis revealed by calculating the mirror Z2 invariant and developing a k.p\neffective Hamiltonian. Additionally, considerable drumhead-like surface states\nwith unique connection patterns are illustrated to identify the non-trivial\nband topology, which may be measured by future experiments."
    },
    {
        "anchor": "First Principles Calculations of Fe on GaAs (100): We have calculated from first principles the electronic structure of 0.5\nmonolayer upto 5 monolayer thick Fe layers on top of a GaAs (100) surface. We\nfind the Fe magnetic moment to be determined by the Fe-As distance. As\nsegregates to the top of the Fe film, whereas Ga most likely is found within\nthe Fe film. Moreover, we find an asymmetric in-plane contraction of our\nunit-cell along with an expansion perpendicular to the surface. We predict the\nnumber of Fe 3d-holes to increase with increasing Fe thickness on $p$-doped\nGaAs.",
        "positive": "Anisotropic electronic phase transition in CrN epitaxial thin films: Electronic phase transition in strongly correlated materials is extremely\nsensitive to the dimensionality and crystallographic orientations. Transition\nmetal nitrides (TMNs) are seldom investigated due to the difficulty in\nfabricating the high-quality and stoichiometric single crystals. In this\nletter, we report the epitaxial growth and electronic properties of CrN films\non different-oriented NdGaO3 (NGO) substrates. Astonishingly, the CrN films\ngrown on (110)-oriented NGO substrates maintain a metallic phase, whereas the\nCrN films grown on (010)-oriented NGO substrates are semiconducting. We\nattribute the unconventional electronic transition in the CrN films to the\nstrongly correlation with epitaxial strain. The effective modulation of bandgap\nby the anisotropic strain triggers the metal-to-insulator transition\nconsequently. This work provides a convenient approach to modify the electronic\nground states of functional materials using anisotropic strain and further\nstimulates the investigations of TMNs."
    },
    {
        "anchor": "Space-time approach to microstructure selection in solid-solid\n  transitions: Nucleation of a solid in solid is initiated by the appearance of distinct\ndynamical heterogeneities, consisting of `active' particles whose trajectories\nshow an abrupt transition from ballistic to diffusive, coincident with the\ndiscontinuous transition in microstructure from a {\\it twinned martensite} to\n{\\it ferrite}. The active particles exhibit intermittent jamming and flow. The\nnature of active particle trajectories decides the fate of the transforming\nsolid -- on suppressing single particle diffusion, the transformation proceeds\nvia rare string-like correlated excitations, giving rise to twinned martensitic\nnuclei. These string-like excitations flow along ridges in the potential energy\ntopography set up by inactive particles. We characterize this transition using\na thermodynamics in the space of trajectories in terms of a dynamical action\nfor the active particles confined by the inactive particles. Our study brings\ntogether the physics of glass, jamming, plasticity and solid nucleation.",
        "positive": "Coupled nonpolar-polar metal-insulator transition in 1:1\n  SrCrO$_3$/SrTiO$_3$ superlattices: A first-principles study: Using first principles calculations, we determined the epitaxial-strain\ndependence of the ground state of the 1:1 SrCrO$_3$/SrTiO$_3$ superlattice. The\nsuperlattice layering leads to significant changes in the electronic states\nnear the Fermi level, derived from Cr $t_{2g}$ orbitals. An insulating phase is\nfound when the tensile strain is greater than 2.2\\% relative to unstrained\ncubic SrTiO$_3$. The insulating character is shown to arise from Cr $t_{2g}$\norbital ordering, which is produced by an in-plane polar distortion that\ncouples to the superlattice d-bands and is stabilized by epitaxial strain. This\neffect can be used to engineer the band structure near the Fermi level in\ntransition metal oxide superlattices."
    },
    {
        "anchor": "Thermoelectric properties of $\u03b2$-As, Sb and Bi monolayers: Monolayer semiconductors of group-VA elements (As, Sb, Bi) with graphenelike\nbuckled structure offer a potential to achieve nanoscale electronic,\noptoelectronic and thermoelectric devices. Motivated by recently-fabricated Sb\nmonolayer, we systematically investigate the thermoelectric properties of\n$\\beta$-As, Sb and Bi monolayers by combining the first-principles calculations\nand semiclassical Boltzmann transport theory. The generalized gradient\napproximation (GGA) plus spin-orbit coupling (SOC) is adopted for the electron\npart, and GGA is employed for the phonon part. It is found that SOC has\nimportant influences on their electronic structures, especially for Bi\nmonolayer, which can induce observable SOC effects on electronic transport\ncoefficients. More specifically, SOC not only has detrimental influences on\nelectronic transport coefficients, but also produces enhanced effects. The\ncalculated lattice thermal conductivity decreases gradually from As to Bi\nmonolayer, and the corresponding room-temperature sheet thermal conductance is\n161.10 $\\mathrm{W K^{-1}}$, 46.62 $\\mathrm{W K^{-1}}$ and 16.02 $\\mathrm{W\nK^{-1}}$, which can be converted into common lattice thermal conductivity by\ndividing by the thickness of 2D material. The sheet thermal conductance of Bi\nmonolayer is lower than one of other 2D materials, such as semiconducting\ntransition-metal dichalcogenide monolayers and orthorhombic group IV-VI\nmonolayers. A series of scattering time is employed to estimate the\nthermoelectric figure of merit $ZT$. It is found that the n-type doping has\nmore excellent thermoelectric properties than p-type doping for As and Bi\nmonolayer, while the comparative $ZT$ between n- and p-type doping is observed\nin Bi monolayer. These results can stimulate further experimental works to open\nthe new field for thermoelectric devices based on monolayer of group-VA\nelements.",
        "positive": "PyQMC: an all-Python real-space quantum Monte Carlo module in PySCF: We describe a new open-source Python-based package for high accuracy\ncorrelated electron calculations using quantum Monte Carlo (QMC) in real space:\nPyQMC. PyQMC implements modern versions of QMC algorithms in an accessible\nformat, enabling algorithmic development and easy implementation of complex\nworkflows. Tight integration with the PySCF environment allows for simple\ncomparison between QMC calculations and other many-body wave function\ntechniques, as well as access to high accuracy trial wave functions."
    },
    {
        "anchor": "Creep properties and deformation mechanisms of single-crystalline\n  $\u03b3^\\prime$-strengthened superalloys in dependence of the Co/Ni ratio: Co-base superalloys are considered as promising high temperature materials\nbesides the well-established Ni-base superalloys. However, Ni appears to be an\nindispensable alloying element also in Co-base superalloys. To address the\ninfluence of the base elements on the deformation behavior, high-temperature\ncompressive creep experiments were performed on a single crystal alloy series\nthat was designed to exhibit a varying Co/Ni ratio and a constant Al, W and Cr\ncontent. Creep tests were performed at 900 {\\deg}C and 250 MPa and the\nresulting microstructures and defect configurations were characterized via\nelectron microscopy. The minimum creep rates differ by more than one order of\nmagnitude with changing Co/Ni ratio. An intermediate CoNi-base alloy exhibits\nthe overall highest creep strength. Several strengthening contributions like\nsolid solution strengthening of the $\\gamma$ phase, effective diffusion\ncoefficients or stacking fault energies were quantified. Precipitate shearing\nmechanisms differ significantly when the base element content is varied. While\nthe Ni-rich superalloys exhibit SISF and SESF shearing, the Co-rich alloys\ndevelop extended APBs when the $\\gamma^\\prime$ phase is cut. This is mainly\nattributed to a difference in planar fault energies, caused by a changing\nsegregation behavior. As result, it is assumed that the shearing resistivity\nand the occurring deformation mechanisms in the $\\gamma^\\prime$ phase are\ncrucial for the creep properties of the investigated alloy series.",
        "positive": "Stable room-temperature ferromagnetic phase at the FeRh(100) surface: Interfaces and low dimensionality are sources of strong modifications of\nelectronic, structural, and magnetic properties of materials. FeRh alloys are\nan excellent example because of the first-order phase transition taking place\nat $\\sim$400 K from an antiferromagnetic phase at room temperature to a high\ntemperature ferromagnetic one. It is accompanied by a resistance change and\nvolume expansion of about 1\\%. We have investigated the electronic and magnetic\nproperties of FeRh(100) epitaxially grown on MgO by combining spectroscopies\ncharacterized by different probing depths, namely X-ray magnetic circular\ndichroism and photoelectron spectroscopy. We thus reveal that the symmetry\nbreaking induced at the Rh-terminated surface stabilizes a surface\nferromagnetic layer involving five planes of Fe and Rh atoms in the nominally\nantiferromagnetic phase at room temperature. First-principles calculations\nprovide a microscopic description of the structural relaxation and the electron\nspin-density distribution that fully support the experimental findings."
    },
    {
        "anchor": "Simple approximate formulas for postbuckling deflection of heavy elastic\n  columns: Columnar buckling is a ubiquitous phenomenon that occurs in both living\nthings and man-made objects, regardless of the length scale ranging from\nmacroscopic to nanometric structures. In general, analyzing the post-buckling\nbehavior of a column requires the application of complex mathematical methods\nbecause it involves nonlinear problem solving. To complement these complex\nmethods, this study presents simple analytical formulas for the large\ndeflection of a heavy elastic column under combined loads. The analytical\nformulas relate the concentrated load acting on the tip of the column, the\ncolumn's own weight, and the deflection angle of the column through a simple\nmathematical expression. This can assist in obtaining an overall picture of the\npost-buckling behavior of heavy columns from an application point of view.",
        "positive": "Basal Slip in Laves Phases: the Synchroshear Dislocation: Two different mechanisms have been reported in previous ab initio studies to\ndescribe basal slip in complex intermetallic Laves phases: synchroshear and\nundulating slip. To date, no clear answer has been given on which is the\nenergetically favourable mechanism and whether either of them could effectively\npropagate as a dislocation. Using classical atomistic simulations supported by\nab initio calculations, the present work removes the ambiguity and shows that\nthe two mechanisms are, in fact, identical. Furthermore, we establish\nsynchroshear as the mechanism for propagating dislocations within the basal\nplane in Laves phases."
    },
    {
        "anchor": "A Search for Alternative Solid Rocket Propellant Oxidizers: Carbon-based caged and heterocyclic compounds tend to have strained molecular\nstructures leading to high heats of formation and energetic behavior. In the\ncurrent paper, molecular modelling calculations for 10 caged compounds of this\ntype along with 2 strained aliphatic compounds and 4 simple cyclic chains are\npresented in view of their possible use as oxidizers in propulsion\napplications. Density functional theory (B3LYP) was employed for the geometry\noptimization of the proposed molecular structure using the 6-311++G(d,p) basis\nset. Heats of formation of the compounds were calculated using the molecular\nmodeling results and their specific impulses were computed using the NASA CEA\n[1] software package to evaluate their potentials as propellant oxidizers.",
        "positive": "Directional carrier transport in micrometer-thick gallium oxide films\n  for high-performance deep-ultraviolet photodetection: Incorporating emerging ultrawide bandgap semiconductors with a\nmetal-semiconductor-metal (MSM) architecture is highly desired for\ndeep-ultraviolet (DUV) photodetection. However, synthesis-induced defects in\nsemiconductors complicate the rational design of MSM DUV photodetectors due to\ntheir dual role as carrier donors and trap centers, leading to a commonly\nobserved trade-off between responsivity and response time. Here, we demonstrate\na simultaneous improvement of these two parameters in {\\epsilon}-Ga2O3 MSM\nphotodetectors by establishing a low-defect diffusion barrier for directional\ncarrier transport. Specifically, using a micrometer thickness far exceeding its\neffective light absorption depth, the {\\epsilon}-Ga2O3 MSM photodetector\nachieves over 18-fold enhancement of responsivity and simultaneous reduction of\nthe response time, which exhibits a state-of-the-art photo-to-dark current\nratio near 10^8, a superior responsivity of >1300 A/W, an ultrahigh detectivity\nof >10^16 Jones and a decay time of 123 ms. Combined depth-profile\nspectroscopic and microscopic analysis reveals the existence of a broad\ndefective region near the lattice-mismatched interface followed by a more\ndefect-free dark region, while the latter one serves as a diffusion barrier to\nassist frontward carrier transport for substantially enhancing the\nphotodetector performance. This work reveals the critical role of the\nsemiconductor defect profile in tuning carrier transport for fabricating\nhigh-performance MSM DUV photodetectors."
    },
    {
        "anchor": "Dramatic Failure of the Callaway Description of Heat Flow in Boron\n  Arsenide and Boron Antimonide Driven by Phonon Scattering Selection Rules: Callaway's simplified heat flow model is often used to confirm experimental\nrealizations of unconventional, hydrodynamic and Poiseuille phonon transport in\nultrahigh thermal conductivity ($\\kappa$) materials, due to its simplicity and\nlow computational cost. Here, we show that the Callaway model works\nexceptionally well for most ultrahigh-$\\kappa$ materials like diamond and boron\nnitride, but fails dramatically for boron arsenide (BAs) and boron antimonide\n(BSb). This failure is driven by the inability of the Callaway model to\neffectively describe the severely restricted phonon scattering in BAs and BSb,\nwhere many scattering selection rules are activated simultaneously. Our work\nhighlights the powerful predictive capability of the Callaway model, and gives\ninsights into the nature of phonon scattering in ultrahigh-$\\kappa$ materials\nand the suitability of the Callaway's description of heat flow through them.",
        "positive": "Atomic-Precision Fabrication of Quasi-Full-Space Grain Boundaries in\n  Two-Dimensional Hexagonal Boron Nitride: Precise control and in-depth understanding of the interfaces is crucial for\nthe functionality-oriented material design with desired properties. Herein, via\nmodifying the long-standing bicrystal strategy, we proposed a novel nanowelding\napproach to build up interfaces between two-dimensional (2D) materials with\natomic precision. This method enabled us, for the first time, to experimentally\nachieve the quasi-full-parameter-space grain boundaries (GBs) in 2D hexagonal\nboron nitride (h-BN). It further helps us unravel the long-term controversy and\nconfusion on the registry of GBs in h-BN, including i) discriminate the\nrelative contribution of the strain and chemical energy on the registry of GBs;\nii) identify a new dislocation core- Frank partial dislocation and four new\nanti-phase boundaries; and iii) confirm the universal GB faceting. Our work\nprovides a new paradigm to the exploiting of structural-property correlation of\ninterfaces in 2D materials."
    },
    {
        "anchor": "Reflective, polarizing, and magnetically soft amorphous Fe/Si multilayer\n  neutron optics with isotope-enriched 11B4C inducing atomically flat\n  interfaces: The utilization of polarized neutrons is of great importance in scientific\ndisciplines spanning materials science, physics, biology, and chemistry.\nPolarization analysis offers insights into otherwise unattainable sample\ninformation such as magnetic domains and structures, protein crystallography,\ncomposition, orientation, ion-diffusion mechanisms, and relative location of\nmolecules in multicomponent biological systems. State-of-the-art multilayer\npolarizing neutron optics have limitations, particularly low specular\nreflectivity and polarization at higher scattering vectors/angles, and the\nrequirement of high external magnetic fields to saturate the polarizer\nmagnetization. Here, we show that by incorporating 11B4C into Fe/Si\nmultilayers, amorphization and smooth interfaces can be achieved, yielding\nhigher neutron reflectivity, less diffuse scattering and higher polarization.\nMagnetic coercivity is eliminated, and magnetic saturation can be reached at\nlow external fields (>2 mT). This approach offers prospects for significant\nimprovement in polarizing neutron optics, enabling; nonintrusive positioning of\nthe polarizer, enhanced flux, increased data accuracy, and further\npolarizing/analyzing methods at neutron scattering facilities.",
        "positive": "Electron diffraction based techniques in scanning electron microscopy of\n  bulk materials: The three scanning electron microscope diffraction based techniques of\nelectron channelling patterns (ECPs), electron channelling contrast imaging\n(ECCI), and electron back scatter diffraction (EBSD) are reviewed. The\ndynamical diffraction theory is used to describe the physics of electron\nchannelling, and hence the contrast observed in ECPs (and EBSD) and ECCI images\nof dislocations. Models for calculating channelling contrast are described and\ntheir limitations discussed. The practicalities of the experimental methods,\nincluding detector-specimen configurations, spatial resolution and\nsensitivities are given. Examples are given of the use of ECCI for imaging and\ncharacterising lattice defects, both individually and in groups, in\nsemiconductor heterostructures and fatigued metals. Applications of the EBSD\ntechnique to orientation determination, phase identification and strain\nmeasurement are given and compared with use of ECPs.. It is concluded that\nthese techniques make the SEM a powerful instrument for characterising the\nlocal crystallography of bulk materials at the mesoscopic scale."
    },
    {
        "anchor": "Anti-doping in Insulators and Semiconductors having Intermediate Bands\n  with Trapped Carriers: Ordinary doping by electrons (holes) generally means that the Fermi level\nshifts towards the conduction band (valence band) and that the conductivity of\nfree carriers increases. Recently, however, some peculiar doping\ncharacteristics were sporadically recorded in different materials without\nnoting the mechanism: electron doping was observed to cause a portion of the\nlowest unoccupied band to merge into the valance band, leading to a decrease in\nconductivity. This behavior we dub as 'anti-doping' was seen in rare-earth\nnickel oxides SmNiO3, cobalt oxides SrCoO2.5, Li-ion battery materials and even\nMgO with metal vacancies. We describe the physical origin of anti-doping as\nwell as its inverse problem, the 'design principles' that would enable\nintelligent search of materials. We find that electron anti-doping is expected\nin materials having pre-existing trapped holes and is caused by annihilation of\nsuch 'hole polarons' via electron doping. This may offer an unconventional way\nof controlling conductivity.",
        "positive": "Single-image based deep learning for precise atomic defects\n  identification: Defect engineering has been profoundly employed to confer desirable\nfunctionality to materials that pristine lattices inherently lack. Although\nsingle atomic-resolution scanning transmission electron microscopy (STEM)\nimages are widely accessible for defect engineering, harnessing atomic-scale\nimages containing various defects through traditional image analysis methods is\nhindered by random noise and human bias. Yet the rise of deep learning (DL)\noffering an alternative approach, its widespread application is primarily\nrestricted by the need for large amounts of training data with labeled ground\ntruth. In this study, we propose a two-stage method to address the problems of\nhigh annotation cost and image noise in the detection of atomic defects in\nmonolayer 2D materials. In the first stage, to tackle the issue of data\nscarcity, we employ a two-state transformation network based on U-GAT-IT for\nadding realistic noise to simulated images with pre-located ground truth\nlabels, thereby infinitely expanding the training dataset. In the second stage,\natomic defects in monolayer 2D materials are effectively detected with high\naccuracy using U-Net models trained with the data generated in the first stage,\navoiding random noise and human bias issues. In both stages, we utilize\nsegmented unit-cell-level images to simplify the model's task and enhance its\naccuracy. Our results demonstrate that not only sulfur vacancies, we are also\nable to visualize oxygen dopants in monolayer MoS2, which are usually\noverwhelmed by random background noise. As the training was based on a few\nsegmented unit-cell-level realistic images, this method can be readily extended\nto other 2D materials. Therefore, our results outline novel ways to train the\nmodel with minimized datasets, offering great opportunities to fully exploit\nthe power of machine learning (ML) applicable to a broad materials science\ncommunity."
    },
    {
        "anchor": "Hot carrier distribution engineering by alloying: picking elements for\n  the desired purposes: Metal alloys hold the promise of providing hot carrier generation\ndistributions superior to pure metals in applications such as sensing,\ncatalysis and solar energy harvesting. Guidelines for finding the optimal alloy\nconfiguration for a target application require understanding the connection\nbetween alloy composition and hot carrier distribution. Here we present a\nDFT-based computational approach to investigate the photo-generated hot carrier\ndistribution of metal alloys based on the joint density of states and the\nelectronic structure. We classified the metals by their electronic structure\ninto closed d-shell, open d-shell, p-block and s-block elements. It is shown\nthat combining closed d-shell elements enables modulating the distribution of\nhighly energetic holes typical of pure metals but also leads to hot carrier\nproduction by IR light excitation and the appearance of highly energetic\nelectrons due to band folding and splitting. This feature arises as an emergent\nproperty of alloying and is only unveiled when the hot carrier distribution\ncomputation takes momentum conservation into account. The combination of closed\nd-shell with open d-shell elements allows an abundant production of hot\ncarriers in a broad energy range, while alloying a closed d-shell elements with\nan s-block element opens the door to hot electron distribution skewed toward\nhigh energy electrons. The combination of d-shell with p-block elements results\nin moderate hot carrier distribution whose asymmetry can be tuned by\ncomposition. Overall, the obtained insights that connect alloy composition,\nband structure and resulting carrier distribution provide a toolkit to match\nelements in an alloy for the deliberate engineering of hot carrier\ndistribution.",
        "positive": "In situ AFM Observations of Li-Oxygen Electrochemical Reactions: The morphologies of crystalline lithium peroxide (Li2O2) discharge products\nin Li-O2 batteries have been shown to exhibit a dependency on subtle variations\nwithin the battery cell-operating environment including exposure to ambient\nair, moisture, or additives. As a result, imaging battery discharge products in\nreal time under carefully controlled environmental conditions is a challenging\nobstacle for complete mechanistic understanding of Li2O2 growth and deposition\nduring discharge in metal-air batteries. Here, we report the design of a\ncompletely enclosed cell for high-resolution in situ AFM imaging of Li-O2\nbattery discharge products. The air-and moisture-free electrochemical cell\nenvironment enabled the observation of different product morphologies during\nAFM imaging when LiTFSI in oxygen-saturated tetraethylene glycol dimethyl ether\n(tetraglyme) solvent was employed. This in situ AFM cell development brings\ncomplimentary information to various proposed mechanisms for lithium oxygen\nreaction."
    },
    {
        "anchor": "Point Group Symmetry and Deformation Induced Symmetry Breaking of\n  Superlattice Materials: The point group symmetry of materials is closely related to their physical\nproperties and quite important for material modeling. However, superlattice\nmaterials have more complex symmetry conditions than crystals due to their\nmultilevel structural feature. Thus, a theoretical framework is proposed to\ncharacterize and determine the point group symmetry of nonmagnetic superlattice\nmaterials systematically. A variety of examples are presented to show the\nsymmetry features of superlattice materials in different dimensions and scales.\nIn addition, the deformation induced symmetry breaking phenomenon is also\nstudied for superlattice materials, which has potential application in tuning\nphysical properties by imposing a strain field.",
        "positive": "Remarks on some open problems in phase-field modelling of solidification: Three different topics in phase-field modelling of solidification are\ndiscussed, with particular emphasis on the limitations of the currently\navailable modelling approaches. First, thin-interface limits of two-sided\nphase-field models are examined, and it is shown that the antitrapping current\nis in general not sufficient to remove all thin-interface effects. Second,\norientation-field models for polycrystalline solidification are analysed, and\nit is shown that the standard relaxational equation of motion for the\norientation field is incorrect in coherent polycrystalline matter. Third, it is\npointed out that the standard procedure to incorporate fluctuations into the\nphase-field approach cannot be used in a straightforward way for a quantitative\ndescription of nucleation."
    },
    {
        "anchor": "Electrode effects on electrical properties of polycrystalline\n  (Ba0.6Sr0.4)(Zr0.3Ti0.7)O3 thin films: (Ba0.6Sr0.4)(Zr0.3Ti0.7)O3 thin films were grown on IrO2 and Pt coated Si\nsubstrates. Film on Pt electrode showed large dielectric dispersion at lower\nfrequency and on other hand film on IrO2 showed dielectric constant almost\nindependent with frequency up to 1 MHz. Tunability (Loss) on Pt and IrO2 at 1\nMHz were 55% (0.159) and 45% (0.07), respectively. The FOM is also high for\nfilm on IrO2 (620) compared on to the Pt (345). Very low leakage current\ndensity also obtained on IrO2 (1.3 x 10-6 A/cm2) compared to Pt (6.14x10-3\nA/cm2) coated Si substrates.",
        "positive": "Hometronics: Accessible production of graphene suspensions for health\n  sensing applications using only household items: Nanoscience at times can seem out of reach to the developing world and the\ngeneral public, with much of the equipment expensive and knowledge seemingly\nesoteric to nonexperts. Using only cheap, everyday household items, accessible\nresearch with real applications can be shown. Here, graphene suspensions were\nproduced using pencil lead, tap water, kitchen appliances, soaps and coffee\nfilters, with a childrens glue based graphene nanocomposite for highly\nsensitive pulse measurements demonstrated."
    },
    {
        "anchor": "Electronic structure and total energy of interstitial hydrogen in iron:\n  Tight binding models: An application of the tight binding approximation is presented for the\ndescription of electronic structure and interatomic force in magnetic iron,\nboth pure and containing hydrogen impurities. We assess the simple canonical\nd-band description in comparison to a non orthogonal model including s and d\nbands. The transferability of our models is tested against known properties\nincluding the segregation energies of hydrogen to vacancies and to surfaces of\niron. In many cases agreement is remarkably good, opening up the way to quantum\nmechanical atomistic simulation of the effects of hydrogen on mechanical\nproperties.",
        "positive": "Classical model of negative thermal expansion in solids with expanding\n  bonds: We study negative thermal expansion (NTE) in model lattices with multiple\natoms per cell and first- and second-nearest neighbor interactions using the\n(anharmonic) Morse potential. By exploring the phase space of neighbor\ndistances and thermal expansion rates of the bonds, we determine the conditions\nunder which NTE emerges. By permitting all bond lengths to expand at different\nrates, we find that NTE is possible without appealing to fully rigid units.\nNearly constant, large-amplitude, isotropic NTE is observed up to the melting\ntemperature in a classical molecular dynamics model of a $\\mathrm{ReO}_3$-like\nstructure when the rigidity of octahedral units is almost completely\neliminated. Only weak NTE, changing over to positive expansion is observed when\nthe corner-linked octahedra are rigid, with flexible second-neighbor bonds\nbetween neighboring octahedra permitting easy rotation. We observe similar\nchanges to thermal expansion behavior for the diamond lattice: NTE when\nsecond-neighbor interactions are weak to positive thermal expansion when\nsecond-neighbor interactions are strong. From these observations, we suggest\nthat the only essential local conditions for NTE are atoms with low\ncoordination numbers along with very low energies for changing bond angles\nrelative to bond-stretching energies."
    },
    {
        "anchor": "First principles prediction of structural and electronic properties of\n  TlxIn(1-x)N alloy: Structural and electronic properties of zinc blende TlxIn(1-x)N alloy have\nbeen evaluated from first principles. The band structures have been obtained\nwithin the density functional theory (DFT), the modified Becke-Johnson (MBJLDA)\napproach for the exchange-correlation potential, and fully relativistic\npseudopotentials. The calculated band-gap dependence on Tl content in this\nhypothetical alloy exhibits a linear behaviour up to the 25 % of thalium\ncontent where its values become close to zero. In turn, the split-off energy at\nthe Gamma point of the Brillouin zone, related to the spin-orbit coupling, is\npredicted to be comparable in value with the band-gap for relatively low\nthalium contents of about 5 %. These findings suggest TlxIn(1-x)N alloy as a\npromising material for optoelectronic applications. Furthermore, the band\nstructure of TlN reveals some specific properties exhibited by topological\ninsulators.",
        "positive": "Quantitatively Enhanced Reliability and Uniformity of High-\u03ba\n  Dielectrics on Graphene Enabled by Self-Assembled Seeding Layers: The full potential of graphene in integrated circuits can only be realized\nwith a reliable ultra-thin high-{\\kappa} top-gate dielectric. Here, we report\nthe first statistical analysis of the breakdown characteristics of dielectrics\non graphene, which allows the simultaneous optimization of gate capacitance and\nthe key parameters that describe large-area uniformity and dielectric strength.\nIn particular, vertically heterogeneous and laterally homogenous Al2O3 and HfO2\nstacks grown via atomic-layer deposition and seeded by a molecularly thin\nperylene-3,4,9,10-tetracarboxylic dianhydride organic monolayer exhibit high\nuniformities (Weibull shape parameter {\\beta} > 25) and large breakdown\nstrengths (Weibull scale parameter, EBD > 7 MV/cm) that are comparable to\ncontrol dielectrics grown on Si substrates."
    },
    {
        "anchor": "An Atom-Probe Tomographic Study of the Compositional Trajectories During\n  gamma(f.c.c.)/gamma-prime(L12) Phase-Separation in a Ni-Al-Cr-Re Superalloy: The compositional diffusional-trajectories for a phase separation of\ngamma(f.c.c.)/gamma-prime(L12) phases are studied in a quaternary\nNi-10Al-8.5Cr-2Re alloy, aged at 700 deg.C for 0 to 1024 h, utilizing\natom-probe tomography (APT). As the gamma-prime(L12)-precipitates grow, the\nenrichments of Ni, Cr, and Re and depletion of Al on the gamma(f.c.c.)\nmatrix-side develop as a result of diffusional fluxes crossing the\ngamma(f.c.c.)/gamma-prime(L12) interface.The experimental (APT) compositional\ntrajectories of the two-phases, gamma(f.c.c.)/gamma-prime(L12), are displayed\nin a quaternary phase-diagram, employing a tetrahedron, and compared with the\nPhilippe-Voorhees (P-V) coarsening model which includes the off-diagonal terms\nin the diffusion tensor for the multi-component system.",
        "positive": "Lateral Size and Thickness Dependence in Ferroelectric Nanostructures\n  Formed by Localized Domain Switching: Ferroelectric nanostructures can be formed by local switching of domains\nusing techniques such as piezo-force microscopy (PFM). Understanding lateral\nsize effects is important to determine the minimum feature size for writing\nferroelectric nanostructures. To understand these lateral size effects, we use\nthe time-dependent-Ginzburg-Landau equations to simulate localized switching of\ndomains for a PFM type and parallel-plate capacitor configurations. Our\ninvestigations indicate that fringing electric fields lead to switching via 90\ndeg domain wedge nucleation for thicker films while at smaller thicknesses, the\npolarization switches directly by 180 deg rotations. The voltage required to\nswitch the domain increases by decreasing the lateral size and at very small\nlateral sizes the coercive voltage becomes so large that it becomes virtually\nimpossible to switch the domain. In all cases, the width of the switched region\nextends beyond the electrodes, due to fringing."
    },
    {
        "anchor": "Genarris 2.0: A Random Structure Generator for Molecular Crystals: Genarris is an open-source Python package for generating random molecular\ncrystal structures with physical constraints for seeding crystal structure\nprediction algorithms and training machine learning models. Here we present a\nnew version of the code, containing several major improvements. An MPI-based\nparallelization scheme has been implemented, which facilitates the seamless\nsequential execution of user-defined workflows. A new method for estimating the\nunit cell volume based on the single molecule structure has been developed\nusing a machine-learned model trained on experimental structures. A new\nalgorithm has been implemented for generating crystal structures with molecules\noccupying special Wyckoff positions. A new hierarchical structure check\nprocedure has been developed to detect unphysical close contacts efficiently\nand accurately. New intermolecular distance settings have been implemented for\nstrong hydrogen bonds. To demonstrate these new features, we study two specific\ncases: benzene and glycine. For all polymorphs, the final pool either contained\nthe experimental structure, or structures with similar lattice parameters,\nsymmetry, and packing motifs.",
        "positive": "Ni Foam Assisted Synthesis of High Quality Hexagonal Boron Nitride with\n  Large Domain Size and Controllable Thickness: The scalable synthesis of two-dimensional (2D) hexagonal boron nitride (h-BN)\nis of great interest for its numerous applications in novel electronic devices.\nHighly-crystalline h-BN films, with single-crystal sizes up to hundreds of\nmicrons, are demonstrated via a novel Ni foam assisted technique reported here\nfor the first time. The nucleation density of h-BN domains can be significantly\nreduced due to the high boron solubility, as well as the large specific surface\narea of the Ni foam. The crystalline structure of the h-BN domains is found to\nbe well aligned with, and therefore strongly dependent upon, the underlying Pt\nlattice orientation. Growth-time dependent experiments confirm the presence of\na surface mediated self-limiting growth mechanism for monolayer h-BN on the Pt\nsubstrate. However, utilizing remote catalysis from the Ni foam, bilayer h-BN\nfilms can be synthesized breaking the self-limiting effect. This work provides\nfurther understanding of the mechanisms involved in the growth of h-BN and\nproposes a facile synthesis technique that may be applied to further\napplications in which control over the crystal alignment, and the numbers of\nlayers is crucial."
    },
    {
        "anchor": "Phase formation, thermal stability and magnetic moment of cobalt nitride\n  thin films: Cobalt nitride (Co-N) thin films prepared using a reactive magnetron\nsputtering process by varying the relative nitrogen gas flow (\\pn) are studied\nin this work. As \\pn~increases, Co(N), \\tcn, Co$_3$N and CoN phases are formed.\nAn incremental increase in \\pn, after emergence of \\tcn~phase at \\pn=10\\p,\nresults in a continuous expansion in the lattice constant ($a$) of \\tcn. For\n\\pn=30\\p, $a$ maximizes and becomes comparable to its theoretical value. An\nexpansion in $a$ of \\tcn, results in an enhancement of magnetic moment, to the\nextent that it becomes even larger than pure Co. Though such higher (than pure\nmetal) magnetic moment for Fe$_4$N thin films have been theoretically predicted\nand evidenced experimentally, higher (than pure Co) magnetic moment are\nevidenced in this work and explained in terms of large-volume high-moment model\nfor tetra metal nitrides.",
        "positive": "Calculation of a temperature-volume phase diagram of water to inform the\n  study of isochoric freezing down to cryogenic temperatures: Phase diagrams are integral to the application and interpretation of\nmaterials thermodynamics, and none is more ubiquitous than the common\nTemperature-Pressure diagram of water and its many icy phases. Inspired by\nrecent advances in isochoric thermodynamics, we here employ a simple convex\nhull approach to efficiently calculate an updated Temperature-Volume phase\ndiagram for water and five of its solid polymorphs from existing Helmholtz free\nenergy data. We proceed to highlight fundamental similarities between this T-V\ndiagram and conventional binary temperature-concentration (T-x) diagrams,\nprovide the volume coordinates of a variety of three-phase invariant reactions\n(e.g. 'confined' or 'volumetric' eutectics, peritectics, etc.) that occur\namongst the phases of pure water under isochoric or confined conditions, and\ncalculate the phase fraction evolution of Ice Ih with temperature along\nmultiple isochores of interest to experimental isochoric freezing. This work\nprovides a requisite baseline upon which to extend the study of isochoric\nfreezing to cryogenic temperatures, with potential applications in\nthermodynamic metrology, cryovolcanism, and cryopreservation."
    },
    {
        "anchor": "Dynamical chiral symmetry breaking in sliding nanotubes: We discovered in simulations of sliding coaxial nanotubes an unanticipated\nexample of dynamical symmetry breaking taking place at the nanoscale. While\nboth nanotubes are perfectly left-right symmetric and nonchiral, a nonzero\nangular momentum of phonon origin appears spontaneously at a series of critical\nsliding velocities, in correspondence with large peaks of the sliding friction.\nThe non-linear equations governing this phenomenon resemble the rotational\ninstability of a forced string. However, several new elements, exquisitely\n\"nano\" appear here, with the crucial involvement of Umklapp and of sliding\nnanofriction.",
        "positive": "Current Overview of Statistical Fiber Bundles Model and Its Application\n  to Physics-based Reliability Analysis of Thin-film Dielectrics: In this paper, we present a critical overview of statistical fiber bundles\nmodels. We discuss relevant aspects, like assumptions and consequences stemming\nfrom models in the literature and propose new ones. This is accomplished by\nconcentrating on both the physical and statistical aspects of a specific\nload-sharing example, the breakdown (BD) for circuits of capacitors and related\ndielectrics. For series and parallel/series circuits (series/parallel\nreliability systems) of ordinary capacitors, the load-sharing rules are derived\nfrom the electrical laws. This with the BD formalism is then used to obtain the\nBD distribution of the circuit. The BD distribution and Gibbs measure are given\nfor a series circuit and the size effects are illustrated for simulations of\nseries and parallel/series circuits. This is related to the finite weakest link\nadjustments for the BD distribution that arise in large series/parallel\nreliability load-sharing systems, such as dielectric BD, from their extreme\nvalue approximations.\n  An elementary but in-depth discussion of the physical aspects of SiO$_2$ and\nHfO$_2$ dielectrics and cell models is given. This is used to study a\nload-sharing cell model for the BD of HfO$_2$ dielectrics and the BD formalism.\nThe latter study is based on an analysis of Kim and Lee (2004)'s data for such\ndielectrics. Here, several BD distributions are compared in the analysis and\nproportional hazard regression models are used to study the BD formalism. In\naddition, some areas of open research are discussed."
    },
    {
        "anchor": "Observation of tightly bound trions in monolayer MoS2: Two-dimensional (2D) atomic crystals, such as graphene and transition-metal\ndichalcogenides, have emerged as a new class of materials with remarkable\nphysical properties. In contrast to graphene, monolayer MoS2 is a\nnon-centrosymmetric material with a direct energy gap. Strong\nphotoluminescence, a current on-off ratio exceeding 10^8 in field-effect\ntransistors, and efficient valley and spin control by optical helicity have\nrecently been demonstrated in this material. Here we report the spectroscopic\nidentification in doped monolayer MoS2 of tightly bound negative trions, a\nquasi-particle composed of two electrons and a hole. These quasi-particles,\nwhich can be created with valley and spin polarized holes, have no analogue in\nother semiconducting materials. They also possess a large binding energy (~ 20\nmeV), rendering them significant even at room temperature. Our results open up\nnew avenues both for fundamental studies of many-body interactions and for\nopto-electronic and valleytronic applications in 2D atomic crystals.",
        "positive": "Large nonlinear Hall effect and Berry curvature in KTaO3 based\n  two-dimensional electron gas: The two-dimensional electron gas (2DEG) at oxide interfaces exhibits various\nexotic properties stemming from interfacial inversion symmetry breaking. In\nthis work, we report the emergence of large nonlinear Hall effects (NHE) in the\nLaAlO3/KTaO3(111) interface 2DEG under zero magnetic field. Skew scattering was\nidentified as the dominant origin based on the cubic scaling of nonlinear Hall\nconductivity with longitudinal conductivity and the threefold symmetry.\nMoreover, a gate-tunable NHE with pronounced peak and dip was observed and\nreproduced by our theoretical calculation. These results indicate the presence\nof Berry curvature hotspots and thus a large Berry curvature triple at the\noxide interface. Our theoretical calculations confirm the existence of large\nBerry curvatures from the avoided crossing of multiple 5d-orbit bands, orders\nof magnitude larger than that in transition-metal dichalcogenides. NHE offers a\nnew pathway to probe the Berry curvature at oxide interfaces, and facilitates\nnew applications in oxide nonlinear electronics."
    },
    {
        "anchor": "Size dependence of the effective magnetic anisotropy in Co, Ni, Fe, and\n  magnetite nanoparticles: Testing the core-shell-surface-layer (CSSL) model: The stability of the stored information in recording media depends on the\nanisotropy energy Ea = KeffV of nanoparticles (NPs) of volume V or diameter D.\nTherefore, the knowledge of how the effective magnetic anisotropy Keff varies\nwith D for a given system is important for technological applications. In a\nrecent paper [Appl. Phys. Lett. 110 (22), 222409 (2017)], the variation of Keff\nversus D in NPs of maghemite ({\\gamma}-Fe2O3) was best described by the Eq.:\nKeff = Kb + (6KS/D) +Ksh{[1-(2d/D)]-3 -1}, where Kb, KS, and Ksh are the\nanisotropy constants of spins in the core, surface layer, and a shell of\nthickness d, respectively. This core-shell-surface layer (CSSL) model is an\nextension of the often used core-surface layer (CSL) model described by Keff =\nKb + (6KS/D) [Phys. Rev. Lett. 72, 282 (1994)]. The additional term involving\nKsh was found to be necessary to fit the data for smaller NPs of {\\gamma}-Fe2O3\nwith D < 5 nm. Here we check the validity of the CSSL model for metallic\nmagnetic NPs of Co, Ni, Fe and magnetite using Keff vs. D data from published\nliterature. Care was taken in selecting data only for those NPs for which the\neffects of interparticle interactions has been taken into account in\ndetermining Keff. The importance of the new CSSL model is that it describes\nwell the Keff vs. D variation for all particles sizes whereas the core-surface\nlayer model often fails for smaller particles with the notable exception of Fe\nNPs. The verification of the CSSL model for metallic NPs of Co, Ni, and\nmagnetite along with NPs of NiO and {\\gamma}-Fe2O3 validates its general\napplicability.",
        "positive": "Controlled atmosphere electrospinning of organic nanofibers with\n  improved light emission and waveguiding properties: Electrospinning in controlled nitrogen atmosphere is developed for the\nrealization of active polymer nanofibers. Fibers electrospun under controlled\natmospheric conditions are found to be smoother and more uniform than samples\nrealized by conventional electrospinning processes performed in air. In\naddition, they exhibit peculiar composition, incorporating a greatly reduced\noxygen content during manufacturing, which favors enhanced optical properties\nand increases emission quantum yield. Active waveguides with optical losses\ncoefficients lowered by ten times with respect to fibers spun in air are\ndemonstrated through this method. These findings make the process very\npromising for the highly-controlled production of active polymer nanostructures\nfor photonics, electronics and sensing."
    },
    {
        "anchor": "The Role of Reconstructed Surfaces in the Intrinsic Dissipative Dynamics\n  of Silicon Nanoresonators: Dissipation in the flexural dynamics of doubly clamped nanomechanical bar\nresonators is investigated using molecular dynamics simulation. The dependence\nof the quality factor Q on temperature and the size of the resonator is\ncalculated from direct simulation of the oscillation of a series of Si <001>\nbars with bare {100} dimerized surfaces. The bar widths range from 3.3 to\n8.7nm, all with a fixed length of 22nm. The fundamental mode frequencies range\nfrom 40 to 90GHz and Q from 10^2 near 1000K to 10^4 near 50K. The quality\nfactor is shown to be limited by defects in the reconstructed surface.",
        "positive": "Theory of confined plasmonic waves in coaxial cylindrical cables\n  fabricated of metamaterials: We report on the theoretical investigation of the plasmonic wave propagation\nin the coaxial cylindrical cables fabricated of both right-handed medium (RHM)\n[with $\\epsilon >0$, $\\mu >0$] and left-handed medium (LHM) [with\n$\\epsilon(\\omega) <0$, $\\mu(\\omega) <0$], using a Green-function (or response\nfunction) theory in the absence of an applied magnetic field. The\nGreen-function theory generalized to be applicable to such quasi-one\ndimensional systems enables us to derive explicit expressions for the\ncorresponding response functions (associated with the EM fields), which can in\nturn be used to derive various physical properties of the system. The confined\nplasmonic wave excitations in such multi-interface structures are characterized\nby the electromagnetic fields that are localized at and decay exponentially\naway from the interfaces. A rigorous analytical diagnosis of the general\nresults in diverse situations leads us to reproduce exactly the previously\nwell-known results in other geometries, obtained within the different\ntheoretical frameworks. As an application, we present several illustrative\nexamples on the dispersion characteristics of the confined (and extended)\nplasmonic waves in single- and double-interface structures made up of\ndispersive metamaterials interlaced with conventional dielectrics. These\ndispersive modes are also substantiated through the computation of local as\nwell as total density of states. It is observed that the dispersive components\nenable the system to support the simultaneous existence of s- and\np-polarization modes in the system. Such effects as this one are solely\nattributed to the negative-index metamaterials and are otherwise impossible..."
    },
    {
        "anchor": "Unusual ferrimagnetism in CaFe2O4: Incomplete cancellation of collinear antiparallel spins gives rise to\nferrimagnetism. Even if the oppositely polarized spins are owing to the equal\nnumber of a single magnetic element having the same valence state, in\nprinciple, a ferrimagnetic state can still arise from the crystallographic\ninequivalence of the host ions. However, experimental identification of such a\nstate as ferrimagnetic is not straightforward because of the tiny magnitude\nexpected for M and the requirement for a sophisticated technique to\ndifferentiate similar magnetic sites. We report a synchrotron-based resonant\nx-ray investigation at the Fe L2,3 edges on an epitaxial film of CaFe2O4, which\nexhibits two magnetic phases with similar energies. We find that while one\nphase of CaFe2O4 is antiferromagnetic, the other one is ferrimagnetic with an\nantiparallel arrangement of an equal number of spins between two distinct\ncrystallographic sites with very similar local coordination environments. Our\nresults further indicate two distinct origins of an overall minute M; one is\nintrinsic, from distinct Fe3+ sites, and the other one is extrinsic, arising\nfrom defective Fe2+ likely forming weakly-coupled ferrimagnetic clusters. These\ntwo origins are uncorrelated and have very different coercive fields. Hence,\nthis work provides a direct experimental demonstration of ferrimagnetism solely\ndue to crystallographic inequivalence of the Fe3+ as the origin of the weak M\nof CaFe2O4.",
        "positive": "Accurate energy bands calculated by the hybrid quasiparticle\n  self-consistent GW method implemented in the ecalj package: We have recently implemented a new version of the quasiparticle\nself-consistent GW (QSGW) method in the ecalj package released at\nhttp://github.com/tkotani/ecalj. Since the new version of the ecalj is\nnumerically stable and accurate compared to the previous versions, we can\nperform calculations easily without being bothered with setting input\nparameters. Here we examine its ability to describe energy band properties,\ne.g., band-gap energy, eigenvalues at special points and effective mass, for\nvariety of semiconductors and insulators. We treat C, Si, Ge, Sn, SiC (in 2H,\n3C, and 4H structures), (Al, Ga, N)x(N, P, As, Pb), (Zn, Cd, Mg)x(O, S, Se,\nTe), SiO2, HfO2, ZrO2, SrTiO3, PbS, PbTe, MnO, NiO, and HgO. We propose that a\nhybrid QSGW method, where we mix 80 percent of QSGW and 20 percent of LDA,\ngives universally good agreement with experiments for these materials."
    },
    {
        "anchor": "Structure and Binding in Halide Perovskites: Analysis of Static and\n  Dynamic Effects from Dispersion-Corrected Density Functional Theory: We investigate the impact of various levels of approximation in density\nfunctional theory calculations for the structural and binding properties of the\nprototypical halide perovskite MAPbI$_3$. Specifically, we test how the\ninclusion of different correction schemes for including dispersive\ninteractions, and how in addition using hybrid density functional theory,\naffects the results for pertinent structural observables by means of comparison\nto experimental data. In particular, the impact of finite temperature on the\nlattice constants and bulk modulus, and the role of dispersive interactions in\ncalculating them, is examined by using molecular dynamics based on density\nfunctional theory. Our findings confirm previous theoretical work showing that\nincluding dispersive corrections is crucial for accurate calculation of\nstructural and binding properties of MAPbI$_3$. They furthermore highlight that\nusing a computationally much more expensive hybrid density functional has only\nminor consequences for these observables. This allows for suggesting the use of\nsemilocal density functional theory, augmented by pairwise dispersive\ncorrections, as a reasonable choice for structurally more complicated\ncalculations of halide perovskites. Using this method, we perform molecular\ndynamics calculations and discuss the dynamic effect of molecular rotation on\nthe structure of and binding in MAPbI$_3$, which allowed for rationalizing\nmicroscopically the simultaneous occurrence of cubic octahedral symmetry and MA\ndisorder.",
        "positive": "Surface currents and slope selection in crystal growth: We face the problem to determine the slope dependent current during the\nepitaxial growth process of a crystal surface. This current is proportional to\ndelta=(p+) + (p-), where (p+/-) are the probabilities for an atom landing on a\nterrace to attach to the ascending (p+) or descending (p-) step. If the landing\nprobability is spatially uniform, the current is proved to be proportional to\nthe average (signed) distance traveled by an adatom before incorporation in the\ngrowing surface. The phenomenon of slope selection is determined by the\nvanishing of the asymmetry delta. We apply our results to the case of atoms\nfeeling step edge barriers and downward funnelling, or step edge barriers and\nsteering. In the general case, it is not correct to consider the slope\ndependent current j as a sum of separate contributions due to different\nmechanisms."
    },
    {
        "anchor": "Imaging the antiparallel magnetic alignment of adjacent Fe and MnAs thin\n  films: The magnetic coupling between iron and alpha - MnAs in the epitaxial system\nFe/MnAs/GaAs(001) has been studied at the sub-micron scale, using element\nselective x-ray photoemission electron microscopy. At room temperature, MnAs\nlayers display ridges and grooves, alternating alpha (magnetic) and beta\n(non-magnetic) phases. The self-organised microstructure of MnAs and the stray\nfields that it generates govern the local alignment between the Fe and alpha -\nMnAs magnetization directions, which is mostly antiparallel with a marked\ndependence upon the magnetic domain size.",
        "positive": "Charge density wave order and fluctuations above T$_{CDW}$ and below\n  superconducting T$_c$ in the kagome metal CsV$_{3}$Sb$_{5}$: The phase diagram of the kagome metal family \\ch{AV3Sb5} (A = K, Rb, Cs)\nfeatures both superconductivity and charge density wave (CDW) instabilities,\nwhich have generated tremendous recent attention. Nonetheless, significant\nquestions remain. In particular, the temperature evolution and demise of the\nCDW state has not been extensively studied, and little is known about the\nco-existence of the CDW with superconductivity at low temperatures. We report\nan x-ray scattering study of \\ch{CsV3Sb5} over a broad range of temperatures\nfrom 300 K to $\\sim$ 2 K, below the onset of its superconductivity at\n$\\textit{T}_\\text{c}\\sim$ 2.9 K. Order parameter measurements of the\n$2\\times2\\times2$ CDW structure show an unusual and extended linear temperature\ndependence onsetting at $T^*$ $\\sim$ 160 K, much higher than the susceptibility\nanomaly associated with CDW order at $\\textit{T}_\\text{CDW}=94$ K. This implies\nstrong CDW fluctuations exist to $\\sim1.7\\times\\textit{T}_\\text{CDW}$. The CDW\norder parameter is observed to be constant from $T=16$ K to 2 K, implying that\nthe CDW and superconducting order co-exist below $\\textit{T}_\\text{c}$, and, at\nambient pressure, any possible competition between the two order parameters is\nmanifested at temperatures well below $\\textit{T}_\\text{c}$, if at all.\nAnomalies in the temperature dependence in the lattice parameters coincide with\n$\\textit{T}_\\text{CDW}$ for $\\textit{c}(T)$ and with $T^*$ for $a(T)$."
    },
    {
        "anchor": "Avoiding critical-point phonon instabilities in two-dimensional\n  materials: The origin of the stripe formation in epitaxial silicene: The origin of the large-scale stripe pattern of epitaxial silicene on the\nZrB$_2$(0001) surface observed by scanning tunneling microscope experiments is\nrevealed by first-principles calculations. Without stripes, the\n($\\sqrt{3}\\times\\sqrt{3}$)-reconstructed, one-atom-thick Si layer is found to\nexhibit a \"zero-frequency\" phonon instability at the $M$ point. In order to\navoid a divergent response, the relevant phonon mode triggers the spontaneous\nformation of a new phase with a particular stripe pattern offering a way to\nlower both the atomic surface density and the total energy of silicene on the\nparticular substrate. The observed mechanism is a way for the system to handle\nepitaxial strain and may therefore be more common in two-dimensional epitaxial\nmaterials exhibiting a small lattice mismatch with the substrate.",
        "positive": "Reaction rates in squeezed polaron bands controlled by quantum\n  statistics: Reaction rates are often defined using classical statistics for introducing\nthe thermal occupation probabilities. Its predictions for the temperature\ndependence of a rate are found in reasonable agreement with experiments. In\nview of the applications to polaronic systems at lower temperatures under\nstrongly quantized conditions, we now extend the definition so as to\nincorporate quantum statistics as well, Fermi-Dirac for polarons and\nBose-Einstein for bipolarons. We find both extensions feasible."
    },
    {
        "anchor": "Bi monocrystal formation on InAs(111)A and B substrates: The growth of Bi films deposited on both A and B faces of InAs(111) has been\ninvestigated by low-energy electron diffraction, scanning tunneling microscopy,\nand photoelectron spectroscopy using synchrotron radiation. The changes upon Bi\ndeposition of the In 4d and Bi 5d5/2 photoelectron signals allow to get a\ncomprehensive picture of the Bi/InAs(1 1 1) interface. From the initial stages\nthe Bi growth on the A face (In-terminated InAs) is epitaxial, contrary to that\non the B face (As- terminated InAs) that proceeds via the formation of islands.\nAngle-resolved photoelectron spectra show that the electronic structure of a\n$\\approx 10$~BL deposit on the A face is identical to that of bulk Bi, while\nmore than $\\approx 30$ BL are needed for the B face. Both bulk and surface\nstates are well accounted for by fully relativistic ab initio spin-resolved\nphotoemission calculations.",
        "positive": "Structural study of alfa-Bi2O3 under pressure: An experimental and theoretical study of the structural properties of\nmonoclinic bismuth oxide (alfa-Bi2O3) under high pressures is here reported.\nBoth synthetic and mineral bismite powder samples have been compressed up to 45\nGPa and their equations of state have been determined with angle-dispersive\nx-ray diffraction measurements. Experimental results have been also compared to\ntheoretical calculations which suggest the possibility of several phase\ntransitions below 10 GPa. However, experiments reveal only a pressure-induced\namorphisation between 15 and 25 GPa, depending on sample quality and deviatoric\nstresses. The amorphous phase has been followed up to 45 GPa and its nature\ndiscussed."
    },
    {
        "anchor": "Intermittent dislocation density fluctuations in crystal plasticity from\n  a phase-field crystal model: Plastic deformation mediated by collective dislocation dynamics is\ninvestigated in the two-dimensional phase-field crystal model of sheared single\ncrystals. We find that intermittent fluctuations in the dislocation population\nnumber accompany bursts in the plastic strain-rate fluctuations. Dislocation\nnumber fluctuations exhibit a power-law spectral density $1/f^2$ at high\nfrequencies $f$. The probability distribution of number fluctuations becomes\nbimodal at low driving rates corresponding to a scenario where low density of\ndefects alternate at irregular times with high population of defects. We\npropose a simple stochastic model of dislocation reaction kinetics that is able\nto capture these statistical properties of the dislocation density fluctuations\nas a function of shear rate.",
        "positive": "Thermographic measurements of spin-current-induced temperature\n  modulation in metallic bilayers: Spin-to-heat current conversion effects have been investigated in bilayer\nfilms consisting of a paramagnetic metal (PM; Pt, W, or Ta) and a ferromagnetic\nmetal (FM; CoFeB or permalloy). When a charge current is applied to the PM/FM\nbilayer film, a spin current is generated across the PM/FM interface owing to\nthe spin Hall effect in PM. The spin current was found to exhibit cooling and\nheating features depending on the sign of the spin Hall angle of PM, where the\nspin-current-induced contribution is estimated by subtracting the contribution\nof the anomalous Ettingshausen effect in FM monolayer films. We also found that\nthe magnitude of the spin-current-induced temperature modulation in the\nPt/CoFeB film is greater than but comparable to that in the Pt/permalloy film,\nalthough the spin dependence of the Peltier coefficient for CoFeB is expected\nto be greater than that for permalloy. We discuss the origin of the observed\nbehaviors with the aid of model calculations; the signals in the PM/FM films\nmay contain the contributions not only from the electron-driven spin-dependent\nPeltier effect but also from the magnon-driven spin Peltier effect."
    },
    {
        "anchor": "Model reconstructions for the Si(337) orientation: Although unstable, the Si(337) orientation has been known to appear in\ndiverse experimental situations such as the nanoscale faceting of Si(112), or\nin the case of miscutting a Si(113) surface. Various models for Si(337) have\nbeen proposed over time, which motivates a comprehensive study of the structure\nof this orientation. Such a study is undertaken in this article, where we\nreport the results of a genetic algorithm optimization of the Si(337)-$(2\\times\n1)$ surface. The algorithm is coupled with a highly optimized empirical\npotential for silicon, which is used as an efficient way to build a set of\npossible Si(337) models; these structures are subsequently relaxed at the level\nof ab initio density functional methods. Using this procedure, we retrieve most\nof the (337) reconstructions proposed in previous works, as well as a number of\nnovel ones.",
        "positive": "First-principles calculation of the instability leading to giant inverse\n  magnetocaloric efects: The structural and magnetic properties of functional Ni-Mn-Z (Z = Ga, In, Sn)\nHeusler alloys are studied by first-principles and Monte Carlo methods. The\n\\textit{ab initio} calculations give a basic understanding of the underlying\nphysics which is associated with the strong competition of ferro- and\nantiferromagnetic interactions with increasing chemical disorder. The resulting\n$d$-electron orbital dependent magnetic ordering is the driving mechanism of\nmagnetostructural instability which is accompanied by a drop of magnetization\ngoverning the size of the magnetocaloric effect. The thermodynamic properties\nare calculated by using the \\textit{ab initio} magnetic exchange coupling\nconstants in finite-temperature Monte Carlo simulations, which are used to\naccurately reproduce the experimental entropy and adiabatic temperature changes\nacross the magnetostructural transition."
    },
    {
        "anchor": "Use of Anodic TiO2 Nanotube Layers as Mesoporous Scaffolds for\n  Fabricating CH3NH3PbI3 Perovskite-based Solid State Solar Cells: We optimize the deposition of CH3NH3PbI3 perovskite into mesoporous\nelectrodes consisting of anodic TiO2 nanotube layers. By a simple spin coating\napproach, complete filling of the tube scaffolds is obtained, that leads to\ninterdigitated perovskite structures in conformal contact with the TiO2 tube\ncounterparts. Such assemblies can be used as solid state solar cells in\nhole-transporting material-free configuration, i.e., the tube scaffold serves\nas electron collector and blocking layer, while the perovskite acts as visible\nlight absorber and hole transporting material. We show that the complete\nfilling of the tube scaffold with the perovskite is essential to improve the\nsolar cell efficiency.",
        "positive": "Temperature and terahertz frequency dependence of the dielectric\n  properties of Fe3O4 thin films deposited on Si substrate: The Fe$_3$O$_4$/Si films are considered to be promising materials for THz\nspintronic applications due to their high temperature magnetic transition and\nsemiconducting properties. In this article, we present the real part of the\ndielectric constant ($\\epsilon_1$) and the optical conductivity ($\\sigma_1$) of\nFe$_3$O$_4$ films of different thicknesses deposited on Si substrate\n(Fe$_3$O$_4$/Si) in the THz range at temperatures 2- 300 K. Although the\nmagnetization of the films with thickness $\\geq$ 115 nm shows a clear change at\nthe Verwey transition temperature T$_v$ = 121 K, their optical properties in\nthe THz frequency range are drastically different from each other. We have\nshown that $\\sigma_1$ is maximum and $\\epsilon_1$ is minimum when the\nFe$^{+2}$/Fe$^{+3}$ ratio is equal to 0.54 which is the ratio of Fe+2/Fe+3 for\npure Fe$_3$O$_4$. The $\\sigma_1$ reduces and $\\epsilon_1$ increases at all\ntemperatures when the Fe$^{+2}$/Fe$^{+3}$ ratio deviates from 0.54. We have\nshown that a slight change in the Fe$^{+2}$/Fe$^{+3}$ ratio can induce large\nchanges in the optical properties which shall have implications in the\napplication of the Fe3O4 films in THz spintronics."
    },
    {
        "anchor": "Concurrent transitions in wear rate and surface microstructure in\n  nanocrystalline Ni-W: Nanocrystalline metals are promising materials for wear-resistant\napplications due to their superior strength and hardness, but prior work has\nshown that cyclic loading can lead to coarsening. In this study, scratch wear\ntests were carried out on nanocrystalline Ni-19 at.% W films with an\nas-deposited grain size of 3 nm, with systematic characterization performed\nafter different wear cycles. A new gradient nanograined microstructure is\nobserved and a direct connection between wear rate and subsurface\nmicrostructure is discovered. A second Ni-W specimen with the same composition\nand a 45 nm average grain size is produced by annealing the original specimen.\nSubsequent wear testing shows that an identical subsurface microstructure is\nproduced in this sample, emphasizing the importance of the cross-over in\ndeformation mechanisms for determining the steady-state grain size during wear.",
        "positive": "Probing La(0.7)Sr(0.3)MnO3 multilayers via spin wave resonances: La(0.7)Sr(0.3)MnO3/BiFeO3 and La(0.7)Sr(0.3)MnO3/PbZr20Ti80O3 epitaxial\nheterostructures have been grown on SrTiO3 substrates. Spin wave resonances are\nused to study interface properties of the ferromagnetic La(0.7)Sr(0.3)MnO3. We\nfind that the addition of the BiFeO3 or PbZr20Ti80O3 causes out-of-plane\nsurface pinning of the La(0.7)Sr(0.3)MnO3. We are able to place new limits on\nthe exchange constant D of La(0.7)Sr(0.3)MnO3 grown on these substrates and\nconfirm the presence of uniaxial and biaxial anisotropies caused by the SrTiO3\nsubstrate."
    },
    {
        "anchor": "Nature and Origin of Unusual Properties in Chemically Exfoliated 2D\n  MoS_2: MoS_2 in its two-dimensional (2D) form is known to exhibit many fundamentally\ninteresting and technologically important properties. One of the most popular\nroutes to form extensive amount of such 2D samples is the chemical exfoliation\nroute. However, the nature and origin of the specific polymorph of MoS_2\nprimarily responsible for such spectacular properties has remained\ncontroversial with claims of both T and T' phases as well as metallic and\nsemiconducting natures. We show that a comprehensive scrutiny of the available\nliterature data of Raman spectra from such samples allow little scope for such\nambiguities, providing overwhelming evidence for the formation of the T' phase\nas the dominant metastable state in all such samples. We also explain that this\nsmall band-gap T' phase may attain substantial conductivity due to thermal and\nchemical doping of charge-carriers, explaining the contradictory claims of\nmetallic and semiconducting nature of such samples, thereby attaining a\nconsistent view of all reports available so far.",
        "positive": "{110} planar faults in strained bcc metals: Origins and implications of\n  a commonly observed artifact of classical potentials: Large-scale atomistic simulations with classical potentials can provide\nvaluable insights into microscopic deformation mechanisms and defect-defect\ninteractions in materials. Unfortunately, these assets often come with the\nuncertainty of whether the observed mechanisms are based on realistic physical\nphenomena or whether they are artifacts of the employed material models. One\nsuch example is the often reported occurrence of stable planar faults (PFs) in\nbody-centered cubic (bcc) metals subjected to high strains, e.g., at crack tips\nor in strained nano-objects. In this paper, we study the strain dependence of\nthe generalized stacking fault energy (GSFE) of {110} planes in various bcc\nmetals with material models of increasing sophistication, i.e., (modified)\nembedded atom method, angular-dependent, Tersoff, and bond-order potentials as\nwell as density functional theory. We show that under applied tensile strains\nthe GSFE curves of many classical potentials exhibit a local minimum which\ngives rise to the formation of stable PFs. These PFs do not appear when more\nsophisticated material models are used and have thus to be regarded as\nartifacts of the potentials. We demonstrate that the local GSFE minimum is not\nformed for reasons of symmetry and we recommend including the determination of\nthe strain-dependent (110) GSFE as a benchmark for newly developed potentials."
    },
    {
        "anchor": "Using a machine learning approach to determine the space group of a\n  structure from the atomic pair distribution function (PDF): We present a method for predicting the space group of a structure given a\ncalculated or measured atomic pair distribution function (PDF) from that\nstructure. The method utilizes machine learning models trained on more than\n100,000 PDFs calculated from structures in the 45 most heavily represented\nspace groups. In particular, we present a convolutional neural network (CNN)\nmodel which yields a promising result that it correctly identifies the space\ngroup among the top-6 estimates 91.9~\\% of the time. The CNN model also\nsuccessfully identifies space groups on 12 out of 15 experimental PDFs. We\ndiscuss interesting aspects of the failed estimates, which indicate that the\nCNN is failing in similar ways as conventional indexing algorithms applied to\nconventional powder diffraction data. This preliminary success of the CNN model\nshows the possibility of model-independent assessment of PDF data on a wide\nclass of materials.",
        "positive": "Co-rich decagonal Al-Co-Ni: predicting structure, orientational order,\n  and puckering: We apply systematic methods previously used by Mihalkovic et al. to predict\nthe structure of the `basic' Co-rich modification of the decagonal Al70 Co20\nNi10 layered quasicrystal, based on known lattice constants and previously\ncalculated pair potentials. The modelling is based on Penrose tile decoration\nand uses Monte Carlo annealing to discover the dominant motifs, which are\nconverted into rules for another level of description. The result is a network\nof edge-sharing large decagons on a binary tiling of edge 10.5 A. A detailed\nanalysis is given of the instability of a four-layer structure towards\n$c$-doubling and puckering of the atoms out of the layers, which is applied to\nexplain the (pentagonal) orientational order."
    },
    {
        "anchor": "Plasmons in Sodium under Pressure: Increasing Departure from\n  Nearly-Free-Electron Behavior: We have measured plasmon energies in Na under high pressure up to 43 GPa\nusing inelastic x-ray scattering (IXS). The momentum-resolved results show\nclear deviations, growing with increasing pressure, from the predictions for a\nnearly-free electron metal. Plasmon energy calculations based on\nfirst-principles electronic band structures and a quasi-classical plasmon model\nallow us to identify a pressure-induced increase in the electron-ion\ninteraction and associated changes in the electronic band structure as the\norigin of these deviations, rather than effects of exchange and correlation.\nAdditional IXS results obtained for K and Rb are addressed briefly.",
        "positive": "Evidence of orbit-selective electronic kagome lattice with planar\n  flat-band in correlated paramagnetic YCr6Ge6: Electronic properties of kagome lattice have drawn great attention recently.\nIn associate with flat-band induced by destructive interference and Dirac\ncone-type dispersion, abundant exotic phenomena have been theoretically\ndiscussed. The material realization of electronic kagome lattice is a crucial\nstep towards comprehending kagome physics and achieving novel quantum phases.\nHere, combining angle-resolved photoemission spectroscopy, transport\nmeasurements and first-principle calculations, we expose a planar flat-band in\nparamagnetic YCr6Ge6 as a typical signature of electronic kagome lattice. We\nunearth that the planar flat-band arises from the d_(z^2 ) electrons with\nintra-kagome-plane hopping forbidden by destructive interference. On the other\nhand, the destructive interference and flatness of the d_(x^2-y^2 ) and d_xy\nbands are decomposed possibly due to additional in-plane hopping terms, but the\nDirac cone-type dispersion is reserved near chemical potential. We explicitly\nunveil that orbital character plays an essential role to realize electronic\nkagome lattice in bulk materials with transition metal kagome layers.\nParamagnetic YCr6Ge6 provides an opportunity to comprehend intrinsic properties\nof electronic kagome lattice as well as its interplays with spin orbit coupling\nand electronic correlation of Cr-3d electrons, and be free from complications\ninduced by strong local moment of ions in kagome planes."
    },
    {
        "anchor": "Quantum Imaging of Magnetic Phase Transitions and Spin Fluctuations in\n  Intrinsic Magnetic Topological Nanoflakes: Topological materials featuring exotic band structures, unconventional\ncurrent flow patterns, and emergent organizing principles offer attractive\nplatforms for the development of next-generation transformative quantum\nelectronic technologies. The family of MnBi2Te4 (Bi2Te3)n materials is\nnaturally relevant in this context due to their nontrivial band topology,\ntunable magnetism, and recently discovered extraordinary quantum transport\nbehaviors. Despite numerous pioneering studies, to date, the local magnetic\nproperties of MnBi2Te4 (Bi2Te3)n remain an open question, hindering a\ncomprehensive understanding of their fundamental material properties.\nExploiting nitrogen-vacancy (NV) centers in diamond, we report nanoscale\nquantum imaging of magnetic phase transitions and spin fluctuations in\nexfoliated MnBi2Te4 (Bi2Te3)n flakes, revealing the underlying spin transport\nphysics and magnetic domains at the nanoscale. Our results highlight the unique\nadvantage of NV centers in exploring the magnetic properties of emergent\nquantum materials, opening new opportunities for investigating the interplay\nbetween topology and magnetism.",
        "positive": "Strain-induced metallization and defect suppression at zipper-like\n  interdigitated atomically thin interfaces enabling high-efficiency halide\n  perovskite solar cells: Halide perovskite light absorbers have great advantages for photovoltaics\nsuch as efficient solar energy absorption, but charge accumulation and\nrecombination at the interface with an electron transport layer (ETL) remains a\nmajor challenge in realizing their full potential. Here we report the\nexperimental realization of a zipper-like interdigitated interface between a\nPb-based halide perovskite light absorber and an oxide ETL by the PbO capping\nof the ETL surface, which produces an atomically thin two-dimensional metallic\nlayer that can significantly enhance the perovskite/ETL charge extraction\nprocess. As the atomistic origin of the emergent two-dimensional interfacial\nmetallicity, first-principles calculations performed on the representative\nMAPbI$_3$/TiO$_2$ interface identify the interfacial strain induced by the\nsimultaneous formation of stretched I-substitutional Pb bonds (and thus Pb-I-Pb\nbonds bridging MAPbI$_3$ and TiO$_2$) and contracted substitutional Pb-O bonds.\nDirect and indirect experimental evidences for the presence of interfacial\nmetallic states are provided, and a non-conventional defect-passivating nature\nof the strained interdigitated perovskite/ETL interface is emphasized. It is\nexperimentally demonstrated that the PbO capping method is generally applicable\nto other ETL materials including ZnO and SrTiO$_3$, and that the zipper-like\ninterdigitated metallic interface leads to about two-fold increase in charge\nextraction rate. Finally, in terms of the photovoltaic efficiency, we observe a\nvolcano-type behavior with the highest performance achieved at the\nmonolayer-level PbO capping. The method established here might prove to be a\ngeneral interface engineering approach to realize high-performance perovskite\nsolar cells."
    },
    {
        "anchor": "Structural fingerprinting in the transmission electron microscope:\n  Overview and opportunities to implement enhanced strategies for nanocrystal\n  identification: This paper illustrates the prospective need for structural fingerprinting\nmethods for nanocrystals. A review of the existing fingerprinting methods for\ncrystal structures by means of transmission electron microscopy which work for\na single setting of the specimen goniometer is given. Suggestions are made on\nhow some of these methods could be enhanced when nanocrystals and novel\ninstrumentation are involved, i.e. when either the kinematic or quasi-kinematic\nscattering approximations are sufficiently well satisfied. A novel strategy for\nlattice-fringe fingerprinting of nanocrystals from Fourier transforms of\nhigh-resolution phase contrast transmission electron microscopy images is\nbriefly outlined. Nanocrystal structure specific limitations to the application\nof this strategy are discussed. An appeal is made to share the structural data\nof nanocrystals freely over the internet and infrastructure that would allow\nthis sharing is mentioned. A shorter version of this paper has been accepted\nfor publication in a special issue on the Structure of Nanocrystals of the\nZeitschrift fuer Kristallographie, International journal for structural,\nphysical, and chemical aspects of crystalline materials.",
        "positive": "Graphene-protected iron layer on Ni(111): Here we report the photoemission studies of intercalation process of Fe\nunderneath graphene layer on Ni(111). The process of intercalation was\nmonitored via XPS of corresponding core levels and UPS of the graphene-derived\n$\\pi$ states in the valence band. \\textit{fcc}-Fe films with thickness of 2-5\nmonolayers at the interface between graphene and Ni(111) form epitaxial\nmagnetic layer passivated from the reactive environment, like for example\noxygen gas."
    },
    {
        "anchor": "Anomalous direction for skyrmion bubble motion: Magnetic skyrmions are localized topological excitations that behave as\nparticles and can be mobile, with great potential for novel data storage\ndevices. In this work, the current-induced dynamics of large skyrmion bubbles\nis studied. When skyrmion motion in the direction opposite to the electron flow\nis observed, this is usually interpreted as a perpendicular spin current\ngenerated by the spin Hall effect exerting a torque on the chiral N\\'{e}el\nskyrmion. By designing samples in which the direction of the net generated spin\ncurrent can be carefully controlled, we surprisingly show that skyrmion motion\nis always against the electron flow, irrespective of the net vertical\nspin-current direction. We find that a negative bulk spin-transfer torque is\nthe most plausible explanation for the observed results, which is qualitatively\njustified by a simple model that captures the essential behaviour. These\nfindings demonstrate that claims about the skyrmion chirality based on their\ncurrent-induced motion should be taken with great caution.",
        "positive": "Domain structure of epitaxial Co films with perpendicular anisotropy: Epitaxial hcp Cobalt films with pronounced c-axis texture have been prepared\nby pulsed lased deposition (PLD) either directly onto Al2O3 (0001) single\ncrystal substrates or with an intermediate Ruthenium buffer layer. The crystal\nstructure and epitaxial growth relation was studied by XRD, pole figure\nmeasurements and reciprocal space mapping. Detailed VSM analysis shows that the\nperpendicular anisotropy of these highly textured Co films reaches the\nmagnetocrystalline anisotropy of hcp-Co single crystal material. Films were\nprepared with thickness t of 20 nm < t < 100 nm to study the crossover from\nin-plane magnetization to out-of-plane magnetization in detail. The analysis of\nthe periodic domain pattern observed by magnetic force microscopy allows to\ndetermine the critical minimum thickness below which the domains adopt a pure\nin-plane orientation. Above the critical thickness the width of the stripe\ndomains is evaluated as a function of the film thickness and compared with\ndomain theory. Especially the discrepancies at smallest film thicknesses show\nthat the system is in an intermediate state between in-plane and out-of-plane\ndomains, which is not described by existing analytical domain models."
    },
    {
        "anchor": "In/GaN(0001)-$\\boldsymbol{{\\mathsf{\\left(\\!\\sqrt{3}\\times\\!\\sqrt{3}\\right)\\!R30^{\\circ}}}}$\n  adsorbate structure as a template for embedded (In,Ga)N/GaN monolayers and\n  short-period superlattices: We explore an alternative way to fabricate (In,Ga)N/GaN short-period\nsuperlattices on GaN(0001) by plasma-assisted molecular beam epitaxy. We\nexploit the existence of an In adsorbate structure manifesting itself by a\n$(\\sqrt{3}\\times\\!\\sqrt{3})\\text{R}30^{\\circ}$ surface reconstruction observed\nin-situ by reflection high-energy electron diffraction. This In adlayer\naccommodates a maximum of 1/3 monolayer of In on the GaN surface and, under\nsuitable conditions, can be embedded into GaN to form an\nIn$_{0.33}$Ga$_{0.67}$N quantum sheet whose width is naturally limited to a\nsingle monolayer. Periodically inserting these quantum sheets, we synthesize\n(In,Ga)N/GaN short-period superlattices with abrupt interfaces and high\nperiodicity as demonstrated by x-ray diffractometry and scanning transmission\nelectron microscopy. The embedded quantum sheets are found to consist of single\nmonolayers with an In content of 0.25-0.29. For a barrier thickness of 6\nmonolayers, the superlattice gives rise to a photoluminescence band at 3.16 eV,\nclose to the theoretically predicted values for these structures.",
        "positive": "Spin phonon coupling in frustrated magnet CdCr$_2$O$_4$: The infrared phonon spectrum of the spinel CdCr2O4 is measured as a function\ntemperature from 6 K to 300K. The triply degenerate Cr phonons soften in the\nparamagnetic phase as temperature is lowered below 100 K and then split into a\nsinglet and doublet in the low T antiferromagnetic phase which is tetragonally\ndistorted to relieve the geometric frustration in the pyrochlore lattice of\nCr$^{3+}$ ions. The phonon splitting is inconsistent with the simple increase\n(decrease) in the force constants due to deceasing (increasing) bond lengths in\nthe tetragonal phase. Rather they correspond to changes in the force constants\ndue to the magnetic order in the antiferromagnetic state. The phonon splitting\nin this system is opposite of that observed earlier in ZnCr2O4 as predicted by\ntheory. The magnitude of the splitting gives a measure of the spin phonon\ncoupling strength which is smaller than in the case of ZnCr2O4."
    },
    {
        "anchor": "Electron-phonon coupling in ferromagnetic Fe-Co alloys from first\n  principles: We calculate from first principles the electron-phonon coupling strength in\nferromagnetic iron-cobalt Fe$_{1-x}$Co$_x$ alloys for compositions ranging from\n$x=0$ to $x=0.75$. We find strong, spin-dependent variation of the\nelectron-phonon coupling strength with alloy composition. The minimum of the\nelectron-phonon interaction is found near the composition $x=0.25$. We analyze\nthe variation of the electron-phonon interaction with composition, as a\nfunction of electron spin, density of states, electron-phonon matrix elements,\nand phonon frequencies. Our results are in good qualitative agreement with\nmagnetization dynamics experiments.",
        "positive": "Magnetic properties of (Fe$_{1-x}$Co$_x$)$_2$B alloys and the effect of\n  doping by 5$d$ elements: We have explored, computationally and experimentally, the magnetic properties\nof \\fecob{} alloys. Calculations provide a good agreement with experiment in\nterms of the saturation magnetization and the magnetocrystalline anisotropy\nenergy with some difficulty in describing Co$_2$B, for which it is found that\nboth full potential effects and electron correlations treated within dynamical\nmean field theory are of importance for a correct description. The material\nexhibits a uniaxial magnetic anisotropy for a range of cobalt concentrations\nbetween $x=0.1$ and $x=0.5$. A simple model for the temperature dependence of\nmagnetic anisotropy suggests that the complicated non-monotonous temperature\nbehaviour is mainly due to variations in the band structure as the exchange\nsplitting is reduced by temperature. Using density functional theory based\ncalculations we have explored the effect of substitutional doping the\ntransition metal sublattice by the whole range of 5$d$ transition metals and\nfound that doping by Re or W elements should significantly enhance the\nmagnetocrystalline anisotropy energy. Experimentally, W doping did not succeed\nin enhancing the magnetic anisotropy due to formation of other phases. On the\nother hand, doping by Ir and Re was successful and resulted in magnetic\nanisotropies that are in agreement with theoretical predictions. In particular,\ndoping by 2.5~at.\\% of Re on the Fe/Co site shows a magnetocrystalline\nanisotropy energy which is increased by 50\\% compared to its parent\n(Fe$_{0.7}$Co$_{0.3}$)$_2$B compound, making this system interesting, for\nexample, in the context of permanent magnet replacement materials or in other\nareas where a large magnetic anisotropy is of importance."
    },
    {
        "anchor": "Extrinsic plastic hardening of polymer thin films in flat punch\n  indentation: Confined geometries offer useful and experimentally amenable mechanical\ntesting arrangements in which to study the molecular and micro-structural\nprocesses which govern plastic yield in stress environments dominated by\nhydrostatic pressure over shear. However, the changes to macroscopic stress\nstrain behaviour that result from switching from an unconfined mode such as\nuniaxial compression to a confined one are often overlooked and display a\nsurprising level of complexity, even for simple elastic plastic constitutive\nmodels. Here we report a confinement induced strain hardening effect in\npolystyrene thin films achieved through repeated plastic loading with a\ncylindrical flat punch whose diameter is many times the initial film thickness.\nThis high aspect ratio combines with constraint provided by film material\nsurrounding the contact to generate a state of confined uniaxial strain in the\nindented region, rendering the deformation one dimensional. By repeated loading\ninto the plastic domain, we achieve a 66% increase in the confined yield\nstress, from 0.3 GPa to 0.5 GPa. Through finite element simulation and analytic\nmodelling of the principal stresses and strains, we show that this effect\narises not from intrinsic changes to the structure of the material, but rather\nresidual stresses imparted during plastic loading. We contrast this effect with\nintrinsic changes to glassy thin films such as physical ageing and thermal\ncross-linking.",
        "positive": "Disentangling the Electronic and Lattice Contributions to the Dielectric\n  Response of Photoexcited Bismuth: Elucidating the interplay between nuclear and electronic degrees of freedom\nthat govern the complex dielectric behavior of materials under intense\nphotoexcitation is essential for tailoring optical properties on demand.\nHowever, conventional transient reflectivity experiments have been unable to\ndifferentiate between real and imaginary components of the dielectric response,\nomitting crucial electron-lattice interactions. Utilizing thin film\ninterference we unambiguously determined the photoinduced change in complex\ndielectric function in the Peierls semimetal bismuth and examined its\ndependence on the excitation density and nuclear motion of the A$_{1g}$ phonon.\nOur modeled transient reflectivity data reveals a progressive broadening and\nredshift of Lorentz oscillators with increasing excitation density and\nunderscores the importance of both, electronic and nuclear coordinates in the\nrenormalization of interband transitions."
    },
    {
        "anchor": "Nuclear quantum effects in ab initio dynamics: theory and experiments\n  for lithium imide: Owing to their small mass, hydrogen atoms exhibit strong quantum behavior\neven at room temperature. Including these effects in first principles\ncalculations is challenging, because of the huge computational effort required\nby conventional techniques. Here we present the first ab-initio application of\na recently-developed stochastic scheme, which allows to approximate nuclear\nquantum effects inexpensively. The proton momentum distribution of lithium\nimide, a material of interest for hydrogen storage, was experimentally measured\nby inelastic neutron scattering experiments and compared with the outcome of\nquantum thermostatted ab initio dynamics. We obtain favorable agreement between\ntheory and experiments for this purely quantum mechanical property, thereby\ndemonstrating that it is possible to improve the modelling of complex\nhydrogen-containing materials without additional computational effort.",
        "positive": "s-d Electronic interactions induced H2 dissociation on the \u03b3-U(100)\n  surface and influences of niobium doping: The dissociation of hydrogen molecules on the \\gamma-U(100) surface is\nsystematically studied with the density functional theory method. Through\npotential energy surface calculations, we find that hydrogen molecules can\ndissociate without any barriers on the clean \\gamma-U(100) surface. After\ncareful electronic analysis, it is found that charge transfer between the\nhydrogen s and uranium d electronic states causes the dissociation, which is\nquite different from the dissociation of hydrogen molecules on other actinide\nmetal surfaces. Considering that doping of 3d transition metal atoms can\nstabilize the \\alpha phase of U, we also study the influences of Nb-doping on\nthe hydrogen dissociation process. We find that the 3d electronic states of Nb\nalso take part in the hybridization with hydrogen s electronic states, which\nleads to the result that hydrogen molecules also dissociate without any energy\nbarriers on the doped U surface. In addition, the free electronic energy lowers\ndown more quickly for a hydrogen molecule approaching the doped U surface."
    },
    {
        "anchor": "From electronic structure to magnetism and skyrmions (Topical review): Solid state theory, density functional theory and its generalizations for\ncorrelated systems together with numerical simulations on supercomputers allow\nnowadays to model magnetic systems realistically and in detail and can be even\nused to predict new materials, paving the way for more rapid material\ndevelopment for applications in energy storage and conversion, information\ntechnologies, sensors, actuators etc. Modelling magnets on different length\nscales (between a few \\r{A}ngstr\\\"om and several micrometers) requires,\nhowever, approaches with very different mathematical formulations. Parameters\ndefining the material in each formulation can be determined either by fitting\nexperimental data or from theoretical calculations and there exists a\nwell-established approach for obtaining model parameters for each length scale\nusing the information from the smaller length scale. In this review, this\napproach will be explained step-by-step in textbook style with examples of\nsuccessful multiscale modelling of different classes of magnetic materials from\nthe research literature as well as based on results newly obtained for this\nreview.",
        "positive": "The frustrated spherical model: an alternative to Ginzburg-Landau\n  Hamiltonians with competing interactions: We solve analytically the Langevin dynamics of the classic spherical model\nconsidering the ferromagnetic exchange and a long-range antiferromagnetic\ninteraction. Our results in the asymptotic regime, shows an equivalence in the\nfunctionality of the spatial and self-correlations between this model and the\nrecently studied Ginzburg-Landau frustrated model within the Hartree\napproximation. A careful discussion is done about the low temperature behavior\nin the context of glassy dynamics. The appearance of interesting features\nregarding the establishment of the ferromagnetic phase is also analyzed in view\nof the effects of the spherical restriction. We propose a new variant of the\nspherical model in which the global restriction is substituted by an infinite\nset of restrictions over finite size regions. This modification leads to a new\ndynamical equation that suggests the appearance of the low temperature phase\ntransition even in the non-frustrated case were the classic spherical model\nfails."
    },
    {
        "anchor": "Intrinsic ionic screening of the ferroelectric polarization of KTP: Mobile charges and lattice polarization interact in ferroelectric materials\nbecause of the Coulomb interaction between the mobile free charges and the\nfixed lattice dipoles. We have investigated this mutual screening in KTiOPO4, a\nferroelectric/superionic single crystal in which the mobile charges are K+\nions. The ionic accumulation close to the crystal surfaces leads to orders of\nmagnitude increase of the Second Harmonic Generation. This ionic space charge\nmodel is supported by the absence of such an effect in non-ionic conductor but\nferroelectric BaTiO3, by its temperature dependence in KTiOPO4 and by its broad\ndepletion at domain walls.",
        "positive": "Coupling efficiency for phase locking of a spin transfer oscillator to a\n  microwave current: The phase locking behavior of spin transfer nano-oscillators (STNOs) to an\nexternal microwave signal is experimentally studied as a function of the STNO\nintrinsic parameters. We extract the coupling strength from our data using the\nderived phase dynamics of a forced STNO. The predicted trends on the coupling\nstrength for phase locking as a function of intrinsic features of the\noscillators i.e. power, linewidth, agility in current, are central to optimize\nthe emitted power in arrays of mutually coupled STNOs."
    },
    {
        "anchor": "Strain-Driven Disproportionation at a Correlated Oxide Metal-Insulator\n  Transition: Metal-to-insulator phase transitions in complex oxide thin films are exciting\nphenomena which may be useful for device applications, but in many cases the\nphysical mechanism responsible for the transition is not fully understood. Here\nwe demonstrate that epitaxial strain generates local disproportionation of the\nNiO6 octahedra, driven through changes in the oxygen stoichiometry, and that\nthis directly modifies the metal-to-insulator phase transition in epitaxial\n(001) NdNiO3 thin films. Theoretically, we predict that the Ni-O-Ni bond angle\ndecreases, while octahedral tilt and local disproportionation of the NiO6\noctahedra increases resulting in a small band gap in otherwise metallic system.\nThis is driven by an increase in oxygen vacancy concentration in the rare-earth\nnickelates with increasing in-plane biaxial tensile strain. Experimentally, we\nfind an increase in pseudocubic unit-cell volume and resistivity with\nincreasing biaxial tensile strain, corroborating our theoretical predictions.\nWith electron energy loss spectroscopy and x-ray absorption, we find a\nreduction of the Ni valence with increasing tensile strain. These results\nindicate that epitaxial strain modifies the oxygen stoichiometry of rare-earth\nperovskite thin films and through this mechanism affect the metal-to-insulator\nphase transition in these compounds.",
        "positive": "Prediction on Elastic Properties of Nb-doped Ni Systems: On the basis of the first principles simulation, the structure, formation\nenthalpy, and mechanical properties (elastic constant, bulk, and shear modulus\nand hardness) of five Nb-doped Ni systems are systematically studied. The\ncalculated equilibrium volume increases with the Nb concentration increasing.\nThe computational elastic constants and formation enthalpy indicate that all\nNb-doped Ni systems are mechanically and thermodynamically stable in our\nresearch. The hardness of these systems also be predicted after the bulk\nmodulus and shear modulus have been accurately calculated. The results show\nthat the hardness increases with the Nb concentration increasing when the Nb\nconcentration below 4.9%, beyond which the hardness will decrease within the\nscope of our study."
    },
    {
        "anchor": "Revealing the Three-Dimensional Arrangement of Polar Topology in\n  Nanoparticles: In the early 2000s, low dimensional systems were predicted to have\ntopologically nontrivial polar structures, such as vortices or skyrmions,\ndepending on mechanical or electrical boundary conditions. A few variants of\nthese structures have been experimentally observed in thin film model systems,\nwhere they are engineered by balancing electrostatic charge and elastic\ndistortion energies. However, the measurement and classification of topological\ntextures for general ferroelectric nanostructures have remained elusive, as it\nrequires mapping the local polarization at the atomic scale in three\ndimensions. Here we unveil topological polar structures in ferroelectric BaTiO3\nnanoparticles via atomic electron tomography, which enables us to reconstruct\nthe full three-dimensional arrangement of cation atoms at an individual atom\nlevel. Our three-dimensional polarization maps reveal clear topological\norderings, along with evidence of size-dependent topological transitions from a\nsingle vortex structure to multiple vortices, consistent with theoretical\npredictions. The discovery of the predicted topological polar ordering in\nnanoscale ferroelectrics, independent of epitaxial strain, widens the research\nperspective and offers potential for practical applications utilizing\ncontact-free switchable toroidal moments.",
        "positive": "Enumeration of spin-space groups: Towards a complete description of\n  symmetries of magnetic orders: Symmetries of three-dimensional periodic scalar fields are described by 230\nspace groups (SGs). Symmetries of three-dimensional periodic (pseudo-) vector\nfields, however, are described by the spin-space groups (SSGs), which were\ninitially used to describe the symmetries of magnetic orders. In SSGs, the\nreal-space and spin degrees of freedom are unlocked in the sense that an\noperation could have different spacial and spin rotations. SSGs gives a\ncomplete symmetry description of magnetic structures, and have natural\napplications in the band theory of itinerary electrons in magnetically ordered\nsystems with weak spin-orbit coupling.\\textit{Altermagnetism}, a concept raised\nrecently that belongs to the symmetry-compensated collinear magnetic orders but\nhas non-relativistic spin splitting, is well described by SSGs. Due to the vast\nnumber and complicated group structures, SSGs have not yet been systematically\nenumerated. In this work, we exhaust SSGs based on the invariant subgroups of\nSGs, with spin operations constructed from three-dimensional (3D) real\nrepresentations of the quotient groups for the invariant subgroups. For\ncollinear and coplanar magnetic orders, the spin operations can be reduced into\nlower dimensional real representations. As the number of SSGs is infinite, we\nonly consider SSGs that describe magnetic unit cells up to 12 times crystal\nunit cells. We obtain 157,289 non-coplanar, 24,788 coplanar-non-collinear, and\n1,421 collinear SSGs. The enumerated SSGs are stored in an online database at\n\\url{https://cmpdc.iphy.ac.cn/ssg} with a user-friendly interface. We also\ndevelop an algorithm to identify SSG for realistic materials and find SSGs for\n1,626 magnetic materials. Our results serve as a solid starting point for\nfurther studies of symmetry and topology in magnetically ordered materials."
    },
    {
        "anchor": "Ab initio Investigation of Thermal Transport in Insulators: Unveiling\n  the Roles of Phonon Renormalization and Higher-Order Anharmonicity: The occurrence of thermal transport phenomena is widespread, exerting a\npivotal influence on the functionality of diverse electronic and\nthermo-electric energy-conversion devices. The traditional first-principles\ntheory governing the thermal and thermodynamic characteristics of insulators\nrelies on the perturbative treatment of interatomic potential and ad-hoc\ndisplacement of atoms within supercells. However, the limitations of these\napproaches for highly anharmonic and weakly bonded materials, along with\ndiscrepancies arising from not considering explicit finite temperature effects,\nhighlight the necessity for a well-defined quasiparticle approach to the\nlattice vibrations. To address these limitations, we present a comprehensive\nnumerical framework in this study, designed to compute the thermal and\nthermodynamic characteristics of crystalline semiconductors and insulators. The\nself-consistent phonon renormalization method we have devised reveals phonons\nas quasiparticles, diverging from their conventional characterization as bare\nnormal modes of lattice vibration. The extension of the renormalization impact\nto interatomic force constants (IFCs) of third and fourth orders is also\nintegrated and demonstrated. For the comprehensive physical insights, we\nemployed an iterative solution of the Peierls-Boltzmann transport equation\n(PBTE) to determine thermal conductivity and carry out Helmholtz free energy\ncalculations, encompassing anharmonicity effects up to the fourth order. In\nthis study, we utilize our numerical framework to showcase its applicability\nthrough an examination of phonon dispersion, phonon linewidth, anharmonic\nphonon scattering, and temperature-dependent lattice thermal conductivity in\nboth highly anharmonic materials (NaCl and AgI) and weakly anharmonic materials\n(cBN and 3C-SiC).",
        "positive": "Direct Evidence of Interaction-Induced Dirac Cones in Monolayer\n  Silicene/Ag(111) System: Silicene, analogous to graphene, is a one-atom-thick two-dimensional crystal\nof silicon which is expected to share many of the remarkable properties of\ngraphene. The buckled honeycomb structure of silicene, along with its enhanced\nspin-orbit coupling, endows silicene with considerable advantages over graphene\nin that the spin-split states in silicene are tunable with external fields.\nAlthough the low-energy Dirac cone states lie at the heart of all novel quantum\nphenomena in a pristine sheet of silicene, the question of whether or not these\nkey states can survive when silicene is grown or supported on a substrate\nremains hotly debated. Here we report our direct observation of Dirac cones in\nmonolayer silicene grown on a Ag(111) substrate. By performing angle-resolved\nphotoemission measurements on silicene(3x3)/Ag(111), we reveal the presence of\nsix pairs of Dirac cones on the edges of the first Brillouin zone of Ag(111),\nother than expected six Dirac cones at the K points of the primary\nsilicene(1x1) Brillouin zone. Our result shows clearly that the unusual Dirac\ncone structure originates not from the pristine silicene alone but from the\ncombined effect of silicene(3x3) and the Ag(111) substrate. This study\nidentifies the first case of a new type of Dirac Fermion generated through the\ninteraction of two different constituents. Our observation of Dirac cones in\nsilicene/Ag(111) opens a new materials platform for investigating unusual\nquantum phenomena and novel applications based on two-dimensional silicon\nsystems."
    },
    {
        "anchor": "Temperature effects in luminescence of associated oxygen-carbon pairs in\n  hexagonal boron nitride under direct optical excitation within 7-1100 K range: We have studied the temperature dependencies of the photoluminescence (PL)\nintensity of 4.1 eV in microcrystalline powder of hexagonal boron nitride in\nthe range of 7-1100 K. The results obtained have been analyzed within the band\nmodel of energy levels of associated donor-acceptor pairs based on impurity\n(ONCN) complexes. Luminescence enhancement processes at T<200 K and two\nindependent channels of external thermal activation quenching are typical of\nthe observable luminescence mechanisms under direct (4.26 eV) excitations of\nthe samples. It has been shown that, at T>220 K, when directly excited, the\nsamples diminish the PL intensity because of the processes of thermal\nionization of the donor level of the ON-center (122 meV) and the deep acceptor\nlevel of the CN-center (1420 meV) as parts of the (ONCN)-complex. The\ntemperature enhancement region with an activation energy of 15 meV is due to\nthe decay of a bound Wannier-Mott exciton followed by transfer of excitation to\nthe associated donor-acceptor pair.",
        "positive": "Interlayer Thermal Conductivity of Rubrene Measured by ac-Calorimetry: We have measured the interlayer thermal conductivity of crystals of the\norganic semiconductor rubrene, using ac-calorimetry. Since ac-calorimetry is\nmost commonly used for measurements of the heat capacity, we include a\ndiscussion of its extension for measurements of the transverse thermal\nconductivity of thin crystals of poor thermal conductors, including the\nlimitations of the technique. For rubrene, we find that the interlayer thermal\nconductivity, 0.7 mW/cm K, is several times smaller than the (previously\nmeasured) in-layer value, but its temperature dependence indicates that the\ninterlayer mean free path is at least a few layers."
    },
    {
        "anchor": "The effect of p-type doping on the oxidation of H-Si(111) studied by\n  second-harmonic generation: Atomic force microscopy and second-harmonic generation data show that boron\ndoping enhances the rate of oxidation of H-terminated silicon. Holes cause a\ngreater increase in the reactivity of the Si-H up bonds than that of the Si-Si\nback bonds.",
        "positive": "Gas Barrier Performance of Graphene/Polymer Nanocomposites: Due to its exceptionally outstanding electrical, mechanical and thermal\nproperties, graphene is being explored for a wide array of applications and has\nattracted enormous academic and industrial interest. Graphene and its\nderivatives have also been considered as promising nanoscale fillers in gas\nbarrier application of polymer nanocomposites (PNCs). In this review, recent\nresearch and development of the utilization of graphene and its derivatives in\nthe fabrication of nanocomposites with different polymer matrices for barrier\napplication are explored. Most synthesis methods of graphene-based PNCs are\ncovered, including solution and melt mixing, in situ polymerization and\nlayer-by-layer process. Graphene layers in polymer matrix are able to produce a\ntortuous path which works as a barrier structure for gases. A high tortuosity\nleads to higher barrier properties and lower permeability of PNCs. The\ninfluence of the intrinsic properties of these fillers (graphene and its\nderivatives) and their state of dispersion in polymer matrix on the gas barrier\nproperties of graphene/PNCs are discussed. Analytical modeling aspects of\nbarrier performance of graphene/PNCs are also reviewed in detail. We also\ndiscuss and address some of the work on mixed matrix membranes for gas\nseparation."
    },
    {
        "anchor": "Many-body theory of phonon-induced spin relaxation and decoherence: First-principles calculations enable accurate predictions of electronic\ninteractions and dynamics. However, computing the electron spin dynamics\nremains challenging. The spin-orbit interaction causes various dynamical\nphenomena that couple with phonons, such as spin precession and spin-flip e-ph\nscattering, which are difficult to describe with current first-principles\ncalculations. In this work, we show a rigorous framework to study\nphonon-induced spin relaxation and decoherence, by computing the spin-spin\ncorrelation function and its vertex corrections due to e-ph interactions. We\napply this approach to a model system and develop corresponding\nfirst-principles calculations of spin relaxation in GaAs. Our vertex-correction\nformalism is shown to capture the Elliott-Yafet, Dyakonov-Perel, and\nstrong-precession mechanisms - three independent spin decoherence regimes with\ndistinct physical origins - thereby unifying their theoretical treatment and\ncalculation. Our method is general and enables quantitative studies of spin\nrelaxation, decoherence, and transport in a wide range of materials and\ndevices.",
        "positive": "Towards understanding flexoelectricity at the nanoscale: We review the authors' recent works on flexoelectricity at the nanoscale\n[arXiv:2010.01747, arXiv:2010.13899], while emphasizing the role of continuum\nmechanics in interpreting the electromechanical response of quantum mechanical\nsystems under bending."
    },
    {
        "anchor": "Impact of stoichiometry and strain on Ge$_{1-x}$Sn$_{x}$ alloys from\n  first principles calculations: We calculate the electronic structure of germanium-tin (Ge$_{1-x}$Sn$_{x}$)\nbinary alloys for $0 \\leq x \\leq 1$ using density functional theory (DFT).\nRelaxed alloys with semiconducting or semimetallic behaviour as a function of\nSn composition $x$ are identified, and the impact of epitaxial strain is\nincluded by constraining supercell lattice constants perpendicular to the [001]\ngrowth direction to the lattice constants of Ge, zinc telluride (ZnTe), or\ncadmium telluride (CdTe) substrates. It is found that application of 1% tensile\nstrain reduces the Sn composition required to bring the (positive) direct band\ngap to zero by approximately 5% compared to a relaxed Ge$_{1-x}$Sn$_{x}$ alloy\nhaving the same gap at $\\Gamma$. On the other hand, compressive strain has\ncomparatively less impact on the alloy band gap at $\\Gamma$. Using DFT\ncalculated alloy lattice and elastic constants, the critical thickness for\nGe$_{1-x}$Sn$_{x}$ thin films as a function of $x$ and substrate lattice\nconstant is estimated, and validated against supercell DFT calculations. The\nanalysis correctly predicts the Sn composition range at which it becomes\nenergetically favourable for Ge$_{1-x}$Sn$_{x}$/Ge to become amorphous. The\ninfluence of stoichiometry and strain is examined in relation to reducing the\nmagnitude of the inverted (``negative'') $\\Gamma_{7}^{-}$-$\\Gamma_{8}^{+}$ band\ngap, which is characteristic of semimetallic alloy electronic structure. Based\non our findings, strategies for engineering the semimetal-to-semiconductor\ntransition via strain and quantum confinement in Ge$_{1-x}$Sn$_{x}$\nnanostructures are proposed.",
        "positive": "Discretization error cancellation in electronic structure calculation: a\n  quantitative study: It is often claimed that error cancellation plays an essential role in\nquantum chemistry and first-principle simulation for condensed matter physics\nand materials science. Indeed, while the energy of a large, or even\nmedium-size, molecular system cannot be estimated numerically within chemical\naccuracy (typically 1 kcal/mol or 1 mHa), it is considered that the energy\ndifference between two configurations of the same system can be computed in\npractice within the desired accuracy.\n  The purpose of this paper is to provide a quantitative study of\ndiscretization error cancellation. The latter is the error component due to the\nfact that the model used in the calculation (e.g. Kohn-Sham LDA) must be\ndiscretized in a finite basis set to be solved by a computer. We first report\ncomprehensive numerical simulations performed with Abinit on two simple\nchemical systems, the hydrogen molecule on the one hand, and a system\nconsisting of two oxygen atoms and four hydrogen atoms on the other hand. We\nobserve that errors on energy differences are indeed significantly smaller than\nerrors on energies, but that these two quantities asymptotically converge at\nthe same rate when the energy cut-off goes to infinity. We then analyze a\nsimple one-dimensional periodic Schr\\\"odinger equation with Dirac potentials,\nfor which analytic solutions are available. This allows us to explain the\ndiscretization error cancellation phenomenon on this test case with\nquantitative mathematical arguments."
    },
    {
        "anchor": "Graphene Oxide vs. Reduced Graphene Oxide as saturable absorbers for\n  Er-doped passively mode-locked fiber laser: In this work we demonstrate comprehensive studies on graphene oxide (GO) and\nreduced graphene oxide (rGO) based saturable absorbers (SA) for mode-locking of\nEr-doped fiber lasers. The paper describes the fabrication process of both\nsaturable absorbers and detailed comparison of their parameters. Our results\nshow, that there is no significant difference in the laser performance between\nthe investigated SA. Both provided stable, mode-locked operation with sub-400\nfs soliton pulses and more than 9 nm optical bandwidth at 1560 nm center\nwavelength. It has been shown that GO might be successfully used as an\nefficient SA without the need of its reduction to rGO. Taking into account\nsimpler manufacturing technology and the possibility of mass production, GO\nseems to be a good candidate as a cost-effective material for saturable\nabsorbers for Er-doped fiber lasers.",
        "positive": "Spin-torque oscillator based on tilted magnetization of the fixed layer: The spin torque oscillator (STO), where the magnetization of the fixed layer\nis tilted out of the film plane, is capable of strong microwave signal\ngeneration in zero magnetic field. Through numerical simulations of the\nLandau-Lifshitz-Gilbert-Slonczewski equations, within a macro-spin\napproximation, we study the microwave signal generation as a function of drive\ncurrent for two realistic tilt angles. The tilt magnetization of the fixed\nlayer can be achieved by using a material with high out-of-plane\nmagnetocrystalline anisotropy, such as L10 FePt."
    },
    {
        "anchor": "Quantum Monte Carlo study on speckle variation due to photorelaxation of\n  ferroelectric clusters in paraelectric barium titanate: Time-dependent speckle pattern of paraelectric barium titanate observed in a\nsoft x-ray laser pump-probe measurement is theoretically investigated as a\ncorrelated optical response to the pump and probe pulses. The scattering\nprobability is calculated based on a model with coupled soft x-ray photon and\nferroelectric phonon mode. It is found that the speckle variation is related\nwith the relaxation dynamics of ferroelectric clusters created by the pump\npulse. Additionally, critical slowing down of cluster relaxation arises on\ndecreasing temperature towards the paraelectric-ferroelectric transition\ntemperature. Relation between critical slowing down, local dipole fluctuation\nand crystal structure are revealed by quantum Monte Carlo simulation.",
        "positive": "Stochastic Continuum Models for High--Entropy Alloys with Short-range\n  Order: High entropy alloys (HEAs) are a class of novel materials that exhibit superb\nengineering properties. It has been demonstrated by extensive experiments and\nfirst principles/atomistic simulations that short-range order in the atomic\nlevel randomness strongly influences the properties of HEAs. In this paper, we\nderive stochastic continuum models for HEAs with short-range order from\natomistic models. A proper continuum limit is obtained such that the mean and\nvariance of the atomic level randomness together with the short-range order\ndescribed by a characteristic length are kept in the process from the atomistic\ninteraction model to the continuum equation. The obtained continuum model with\nshort-range order is in the form of an Ornstein--Uhlenbeck (OU) process. This\nvalidates the continuum model based on the OU process adopted\nphenomenologically by Zhang et al. [Acta Mater., 166 (2019), pp. 424--434] for\nHEAs with short-range order. We derive such stochastic continuum models with\nshort-range order for both elasticity in HEAs without defects and HEAs with\ndislocations (line defects). The obtained stochastic continuum models are based\non the energy formulations, whose variations lead to stochastic partial\ndifferential equations."
    },
    {
        "anchor": "Electronic correlation in the quasi-two-dimensional electride Y$_2$C: Magnetic properties of the electride compound Y$_2$C were investigated by\nmuon spin rotation and magnetic susceptibility on two samples with different\nform (poly- and single-crystalline), to examine the theoretically-predicted\nStoner ferromagnetism for the electride bands. There was no evidence of static\nmagnetic order in both samples even at temperatures down to 0.024 K. For the\npoly-crystalline sample, the presence of a paramagnetic moment at Y sites was\ninferred from the Curie-Weiss behavior of the muon Knight shift and\nsusceptibility, whereas no such tendency was observed in the single-crystalline\nsample. These observations suggest that the electronic ground state of Y$_2$C\nis at the limit between weak-to-strong electronic correlation, where onsite\nCoulomb repulsion is sensitive to a local modulation of the electronic state or\na shift in the Fermi level due to the presence of defects/impurities.",
        "positive": "Dynamics of Electrons and Ab-Initio Modeling of Quantum Transport: In this short paper we first give a very simple derivation of the Landauer\nformula for a 2-point conductance of QJ $G^{2P}$, based on the uncertainty\nprinciple. The aim of this is to introduce this central equation of quantum\ntransport to a general audience. Next we analyse the dynamics of setting up a\nsteady-state current in a simple many-electron system and use these\nobservations to present physical basis and formal result for the 4-point\nconductance $G^{4P}$, rigorously related to the non-local conductivity of an\nextended system consisting of electrodes and their junction."
    },
    {
        "anchor": "Self-repairing in single-walled carbon nanotubes by heat treatment: Structure transformation by heat treatment in single-walled carbon nanotubes\n(SWCNT) is investigated using molecular dynamics simulation. The critical\ntemperature for the collapse of pure SWCNT is as high as 4655 K due to strong\ncovalent carbon-carbon bonding. Above 2000 K, the cross section of SWCNT\nchanges from circle to ellipse. The self-repairing capability is then\ninvestigated and two efficient processes are observed for the SWCNT to repair\nthemselves. (1) In the first mechanism, vacancy defects aggregate to form a\nbigger hole, and a bottleneck junction is constructed nearby. (2) In the second\nmechanism, a local curvature is generated around the isolate vacancy to smooth\nthe SWCNT. Benefit from the powerful self-repairing capability, defective SWCNT\ncan seek a stable configuration at high temperatures; thus the critical\ntemperature for collapse is insensitive to the vacancy defect density.",
        "positive": "Critical Temperatures of a Two-Band Model for Diluted Magnetic\n  Semiconductors: Using Dynamical Mean Field Theory (DMFT) and Monte Carlo (MC) simulations, we\nstudy the ferromagnetic transition temperature Tc of a two-band model for\nDiluted Magnetic Semiconductors (DMS), varying coupling constants, hopping\nparameters, and carrier densities. We found that Tc is optimized at all\nfillings p when both impurity bands (IB) fully overlap in the same energy\nrange, namely when the exchange couplings J and bandwidths are identical. The\noptimal Tc is found to be about twice larger than the maximum value obtained in\nthe one-band model, showing the importance of multiband descriptions of DMS at\nintermediate J's."
    },
    {
        "anchor": "Interfacial Multiferroics of TiO2/PbTiO3 Heterostructure Driven by\n  Ferroelectric Polarization Discontinuity: Novel phenomena appear when two different oxide materials are combined\ntogether to form an interface. For example, at the interface of LaAlO3/SrTiO3,\ntwo dimensional conductive states form to avoid the polar discontinuity and\nmagnetic properties are found at such interface. In this work, we propose a new\ntype of interface between two nonmagnetic and nonpolar oxides that could host a\nconductive state with magnetic properties, where it is the ferroelectric\npolarization discontinuity instead of the polar discontinuity that leads to the\ncharge transfer, forming the interfacial conductive or magnetic states. As a\nconcrete example, we investigate by first-principles calculations the\nheterostructures made of ferroelectric perovskite oxide PbTiO3 and\nnon-ferroelectric polarized oxides TiO2. We show that charge is transferred to\nthe interfacial layer forming an interfacial conductive state with\nferromagnetic ordering that may persist up to room temperature. Especially, the\nstrong coupling between bulk ferroelectric polarization and interface\nferromagnetism represents a new type of magnetoelectric effect, which provides\nan ideal platform for exploring the intriguing interfacial multiferroics. The\nfindings here are important not only for fundamental science but also for\npromising applications in nanoscale electronics and spintronics.",
        "positive": "Influence of Ni doping on the electronic structure of Ni_2MnGa: The modifications in the electronic structure of Ni_{2+x}Mn_{1-x}Ga by Ni\ndoping have been studied using full potential linearized augmented plane wave\nmethod and ultra-violet photoemission spectroscopy. Ni 3d related electron\nstates appear due to formation of Ni clusters. We show the possibility of\nchanging the minority-spin DOS with Ni doping, while the majority-spin DOS\nremains almost unchanged. The total magnetic moment decreases with excess Ni.\nThe total energy calculations corroborate the experimentally reported changes\nin the Curie temperature and the martensitic transition temperature with x."
    },
    {
        "anchor": "In-plane structure and ordering at liquid sodium surfaces and interfaces\n  from ab initio molecular dynamics: Atoms at liquid metal surfaces are known to form layers parallel to the\nsurface. We analyze the two-dimensional arrangement of atoms within such layers\nat the surface of liquid sodium, using ab initio molecular dynamics (MD)\nsimulations based on density functional theory. Nearest neighbor distributions\nat the surface indicate mostly 5-fold coordination, though there are noticeable\nfractions of 4-fold and 6-fold coordinated atoms. Bond angle distributions\nsuggest a movement toward the angles corresponding to a six-fold coordinated\nhexagonal arrangement of the atoms as the temperature is decreased towards the\nsolidification point. We rationalize these results with a distorted hexagonal\norder at the surface, showing a mixture of regions of five and six-fold\ncoordination. The liquid surface results are compared with classical MD\nsimulations of the liquid surface, with similar effects appearing, and with ab\ninitio MD simulations for a model solid-liquid interface, where a pronounced\nshift towards hexagonal ordering is observed as the temperature is lowered.",
        "positive": "Numerical-Diagonalization Study of Spin Gap Issue of the Kagome Lattice\n  Heisenberg Antiferromagnet: We study the system size dependence of the singlet-triplet excitation gap in\nthe $S=1/2$ kagome-lattice Heisenberg antiferromagnet by numerical\ndiagonalization. We successfully obtain a new result of a cluster of 42 sites.\nThe two sequences of gaps of systems with even-number sites and that with\nodd-number sites are separately analyzed. Careful examination clarifies that\nthere is no contradiction when we consider the system to be gapless."
    },
    {
        "anchor": "Solving the issues of multicomponent diffusion in an equiatomic NiCoFeCr\n  medium entropy alloy: Estimating the diffusion coefficients experimentally in a four-component\ninhomogeneous alloy following the conventional diffusion couple method by\nintersecting three couples at the same composition is difficult unless a small\ncomposition range of constant diffusivity is identified. Additionally, the\nintrinsic diffusion coefficients of the components cannot be estimated in a\nsystem with more than two components. To solve these issues, we have followed\nthe pseudo-binary and pseudo-ternary diffusion couple methods for estimating\nthe diffusion coefficients at the equiatomic composition of NiCoFeCr medium\nentropy alloy. Along with the pseudo-binary interdiffusion coefficients, we\nhave estimated the intrinsic diffusion coefficients of all the components by\ndesigning the pseudo-binary couples such that Ni and Co develop the diffusion\nprofiles keeping Fe and Cr constant in one couple and Fe and Cr develop the\ndiffusion profiles keeping Ni and Co constant in another couple. Subsequently,\nwe have proposed the relations for calculating the tracer diffusion\ncoefficients utilizing the thermodynamic details. We have found a good match\nwith the data estimated directly following the radiotracer method at the\nequiatomic composition. Following, we have produced three pseudo-ternary\ndiffusion couples intersecting at the compositions close to the equiatomic\ncomposition. The main pseudo-ternary interdiffusion coefficients of Fe are\nfound to be higher than Ni and Co. Therefore, we have estimated different types\nof diffusion coefficients highlighting the complex diffusion process in the\nfour-component NiCoFeCr medium entropy alloy.",
        "positive": "A case study of bilayered spin-$1/2$ square lattice compound\n  [VO(HCOO)$_2\\cdot$(H$_2$O)]: We present the synthesis and a detail investigation of structural and\nmagnetic properties of polycrystalline [VO(HCOO)$_2\\cdot$(H$_2$O)] by means of\nx-ray diffraction, magnetic susceptibility, high-field magnetization, heat\ncapacity, and electron spin resonance measurements. It crystallizes in a\northorhombic structure with space group $Pcca$. It features distorted VO$_6$\noctahedra connected via HCOO linker (formate anions) forming a two-dimensional\nsquare lattice network with a bilayered structure. Analysis of magnetic\nsusceptibility, high field magnetization, and heat capacity data in terms of\nthe frustrated square lattice model unambiguously establish\nquasi-two-dimensional nature of the compound with nearest neighbour interaction\n$J_1/k_{\\rm B} \\simeq 11.7$~K and next-nearest-neighbour interaction\n$J_2/k_{\\rm B} \\simeq 0.02$~K. It undergoes a N\\'eel antiferromagnetic ordering\nat $T_{\\rm N} \\simeq 1.1$~K. The ratio $\\theta_{\\rm CW}/T_{\\rm N} \\simeq 10.9$\nreflects excellent two-dimensionality of the spin-lattice in the compound. A\nstrong in-plane anisotropy is inferred from the linear increase of $T_{\\rm N}$\nwith magnetic field, consistent with the structural data."
    },
    {
        "anchor": "Thermodynamic interpretation of reactive processes in Ni-Al nanolayers\n  from atomistic simulations: Metals which can form intermetallic compounds by an exothermic reaction\nconstitute a class of reactive materials with multiple applications. Ni-Al\nlaminates of thin alternating layers are being considered as model nanometric\nmetallic multilayers for studying various reaction processes. However, the\nreaction kinetics at short timescales after mixing are not entirely understood.\nIn this work, we calculate the free energies of Ni-Al alloys as a function of\ncomposition and temperature for different solid phases using thermodynamic\nintegration based on state-of-the-art interatomic potentials. We use this\ninformation to interpret molecular dynamics (MD) simulations of bilayer systems\nat 800 K and zero pressure, both in isothermal and isenthalpic conditions. We\nfind that a disordered phase always forms upon mixing as a precursor to a more\nstable nano crystalline B2 phase. We construe the reactions observed in terms\nof thermodynamic trajectories governed by the state variables computed.\nSimulated times of up to 30 ns were achieved, which provides a window to\nphenomena not previously observed in MD simulations. Our results provide\ninsight into the early experimental reaction timescales and suggest that the\npath (segregated reactants)$\\rightarrow$(disordered phase)$\\rightarrow$(B2\nstructure) is always realized irrespective of the imposed boundary conditions.",
        "positive": "Lubricity of graphene on rough Au surfaces: This paper studies the lubricating properties of graphene on randomly rough\nAu surfaces in sliding nanofriction using molecular dynamics. It is shown that\nthe friction and the consequent heat dissipation decrease more than an order of\nmagnitude in the presence of graphene. The performance of graphene nanoribbons\nas lubricants is, however, limited because of detachment and displacement at\nthe interface. Sliding contacts lubricated with a stretched graphene sheet\nexhibit low friction, but possibly also low structural stability. This suggests\nthat the graphene-substrate adherence could be crucial for the lubricity of\ntwo-dimensional materials on rough metal surfaces."
    },
    {
        "anchor": "Investigation of the crystal and magnetic structures of the trigonal\n  multiferroic iron-boracite Fe3B7O13(OH): We have investigated the crystal and magnetic structures of the trigonal\niron-boracite Fe3B7O13X with X = OH by neutron diffraction. Neutron diffraction\nenables us to locate the hydrogen atom of the hydroxyl group and determine the\nmagnetic ground state of this member of the multiferroic boracite family. No\nevidence was found for a monoclinic distortion in the magnetic ordered state.\nThe magnetic symmetry allows for magnetoelectric and ferroelectric properties.\nThe N/'eel tempera- ture TN of 4.86(4) K confirms the general trends within the\nboracites that TN decreases from X = I > Br > Cl > OH. Surprisingly while\nFe3B7O13OH exhibits the largest frustration with $|\\theta/T_N| = 5.6$ within\nthe Fe3B7O13X series, no reduction of the magnetic moment is found using\nneutron diffraction.",
        "positive": "HSH-carbon: A novel sp2-sp3 carbon allotrope with an ultrawide energy\n  gap: A sp2-sp3 hybrid carbon allotrope named HSH-carbon is proposed by the\nfirst-principles calculations. The structure of HSH-carbon can be regarded as a\ntemplate polymerization of [1.1.1]propellane molecules in a hexagonal lattice,\nas well as, an AA stacking of recently reported HSH-C10 consisting of carbon\ntrigonal bipyramids. Based on calculations, the stability of this structure is\ndemonstrated in terms of the cohesive energy, phonon dispersion, Born-Huang\nstability criteria, and ab initio molecular dynamics. HSH-carbon is predicted\nto be a semiconductor with an indirect energy gap of 3.56 eV at the PBE level\nor 4.80 eV at the HSE06 level. It is larger than the gap of Si and close to the\ngap of c-diamond, which indicates HSH-carbon is potentially an ultrawide\nbandgap semiconductor. The effective masses of carriers in the VB and CB edge\nare comparable with wide bandgap semiconductors such as GaN and ZnO. The\nelastic behavior of HSH-carbon such as bulk modulus, Young's modulus and shear\nmodulus is comparable with that of T-carbon and much smaller than that of\nc-diamond, which suggests that HSH-carbon would be much easier to be processed\nthan c-diamond in practice."
    },
    {
        "anchor": "Origin of the Type-II Weyl state in topological antiferromagnetic\n  YbMnBi2: Recently, the topological nature of an antiferromagnet YbMnBi2 has been\ncontroversial. YbMnBi2 is regarded as a candidate of Type-II Weyl semimetals\nwith magnetic moments of Mn atoms canting about 10{\\deg} in some studies but as\na Dirac semimetal without canting in others. By means of systematical density\nfunctional theory calculations, we show the perfect YbMnBi2 bulk has a\ncollinear antiferromagnetic ordering and, naturally, it is a Dirac semimetal.\nConsidering the vital role of magnetic moment canting in generating the Type-II\nWeyl state, we artificially cant the magnetic moments of Mn atoms and find that\nYbMnBi2 enters into the Type-II Weyl state from about 2{\\deg}. Inspired by this\nand taking into account the possible defects in experiments, we suggest that Bi\nvacancies in Mn-Bi-Mn bonds, which produce sizable Dzyaloshinskii-Moriya\ninteractions and thereby cant the magnetic moments of Mn atoms, can tune the\ntopological nature of YbMnBi2 from Dirac semimetals to Type-II Weyl semimetals.\nOur work unveils the possible underlying mechanism for the Type-II Weyl state\nin YbMnBi2, providing insights into the Weyl state in other magnetic\ntopological materials.",
        "positive": "Supercell-core software: a useful tool to generate an optimal supercell\n  for vertically stacked nanomaterials: Vertically oriented materials, such as van der Waals heterostructures, that\nhave novel hybrid properties are crucial for fundamental scientific research\nand the design of new nano-devices. Currently, most available theoretical\nmethods require applying a supercell approach with periodic boundary conditions\nto explore the electronic properties of such nanomaterials. Herein, we present\nsupercell-core software, which provides a way to determine the supercell of\nnon-commensurate lattices, in particular, van der Waals heterostructures.\nAlthough this approach is very common, most of the reported work still uses\nsupercells that are constructed 'by hand' and on a temporary basis. The\ndeveloped software is designed to facilitate finding and constructing optimised\nsupercells (i.e., with small size and minimal strain accumulation in adjacent\nlayers) of vertically stacked lattices."
    },
    {
        "anchor": "Polarization of thin films of barium-strontium titanate under external\n  electric field: The Landau theory of phase transitions of Ba0.8Sr0.2TiO3 thin film under\nexternal electric field applied in the planar geometry is developed. The\ninterfacial van-der-Waals field Ez=1.1x10^8 V/m oriented normal to the\nfilm-substrate interface was introduced in to the model calculation to explain\nexperimentally observed behavior of the polarization as a function of planar\nelectric field. The Ez - misfit strain phase diagram of the film is constructed\nand discussed.",
        "positive": "Local pressure-induced metallization of a semiconducting carbon nanotube\n  in a crossed junction: The electronic and vibrational density of states of a semiconducting carbon\nnanotube in a crossed junction was investigated by elastic and inelastic\nscanning tunneling spectroscopy. The strong radial compression of the nanotube\nat the junction induces local metallization spatially confined to a few nm. The\nlocal electronic modifications are correlated with the observed changes in the\nradial breathing and G-band phonon modes, which react very sensitively to local\nmechanical deformation. In addition, the experiments reveal the crucial\ncontribution of the image charges to the contact potential at nanotube-metal\ninterfaces."
    },
    {
        "anchor": "Multihyperuniform Long-Range Order in Medium-Entropy Alloys: We provide strong numerical evidence for a hidden multihyperuniform\nlong-range order (MHLRO) in SiGeSn medium-entropy alloys (MEAs), in which the\nnormalized infinite-wavelength composition fluctuations for all three atomic\nspecies are completely suppressed as in a perfect crystalline state. We show\nthis MHLRO naturally leads to the emergence of short-range order (SRO) recently\ndiscovered in MEAs, which results in stable lower-energy states compared to\nalloy models with random or special quasi-random structures (SQSs) possessing\nno atomic SROs. The MHLRO MEAs approximately realize the Vegard's law, which\noffers a rule-of-mixture type predictions of the lattice constants and\nelectronic band gap, and thus can be considered as an ideal mixing state. The\nMHLRO also directly gives rise to enhanced electronic band gaps and superior\nthermal transport properties at low temperatures compared to random structures\nand SQSs, which open up novel potential applications in optoelectronics and\nthermoelectrics. Our analysis of the SiGeSn system leads to the formulation of\ngeneral organizing principles applicable in other medium- and high-entropy\nalloys (HEAs), and a highly efficient computational model for rendering\nrealistic large-scale configurations of MEAs and HEAs.",
        "positive": "Convergence and machine learning predictions of Monkhorst-Pack k-points\n  and plane-wave cut-off in high-throughput DFT calculations: In this work, we developed an automatic convergence procedure for k-points\nand plane wave cut-off in density functional (DFT) calculations and applied it\nto more than 30000 materials. The computational framework for automatic\nconvergence can take a user-defined input as a convergence criterion. For\nk-points, we converged energy per cell (EPC) to 0.001 eV/cell tolerance and\ncompared the results with those obtained using an energy per atom (EPA)\nconvergence criteria of 0.001 eV/atom. From the analysis of our results, we\ncould relate k-point density and plane wave cut-off to material parameters such\nas density, the slope of bands, number of band-crossings, the maximum\nplane-wave cut-off used in pseudopotential generation, crystal systems, and the\nnumber of unique species in materials. We also identified some material species\nthat would require more careful convergence than others. Moreover, we\nstatistically investigated the dependence of k-points and cutoff on\nexchange-correlation functionals. We utilized all this data to train machine\nlearning models to predict the k-point line density and plane-wave cut-off for\ngeneralized materials. This would provide users with a good starting point\ntowards converged DFT calculations. The code used, and the converged data are\navailable on the following websites: https://jarvis.nist.gov/, and\nhttps://github.com/usnistgov/jarvis ."
    },
    {
        "anchor": "Local and electronic structure of Sr1-xGdxTiO3 probed by X-ray\n  absorption spectroscopy: Gadolinium-doped strontium titanate is a typical perovskite structure\nmaterial which has been studied due their thermomechanical, termoelectrical and\nelectrochemical properties. In this study, local and electronic structure of\nSr1-xGdxTiO3 samples were analyzed through X-ray absorption spectroscopy\nmeasurements. The results obtained with the adjustment of extended X-ray\nabsorption fine structure (EXAFS) spectra at Sr K-edge show that\ncrystallographic model of Pm-3m space group is consistent with local structure\naround Sr atoms, as expected. This same analysis also reveals an increasing of\nthe Debye-Waller as a function of the Gd content in some shells, which is\nassociated with disorder induced by Sr vacancies due to the heterovalent Gd\nincorporation. EXAFS spectra at Gd LIII-edge for Sr1-xGdxTiO3 samples indicates\nregular GdO12 dodecahedra without displacement of Gd atoms from centrosymmetric\nposition. A disorder was also identified in the shells beyond the first 12 O\nneighbors in which neither the crystallographic cubic structure of the SrTiO3\nnor the orthorhombic structure of the GdTiO3 fits well. X-ray absorption near\nedge spectroscopy (XANES) spectrum at Ti LIII,II-edges shows an asymmetric peak\nbecause of the splitting between the eg orbitals of 3d band for SrTiO3 sample.\nThe addition of Gd atoms to SrTiO3 structure cause an enlargement of this peak\nand this split is associated with a small displacement of Ti atoms from their\ncentrosymmetric position. Several features of the XANES spectra at O k-edge for\nSr1-xGdxTiO3 samples are affected by the increase of Gd concentration.\nAccording to our calculated projected density of states, these transitions are\nrelated to a reduction in the number of unoccupied O 2p - Ti 3d states caused\nby the split of Ti 3d band. Moreover, these XANES spectra also show a\ndependence of the increasing of the hybridization between O 2p and Gd 5d4f6s\nstates.",
        "positive": "Temperature Dependent Ferromagnetic Resonance via the\n  Landau-Lifshitz-Bloch Equation: Application to FePt: Using the Landau-Lifshitz-Bloch (LLB) equation for ferromagnetic materials,\nwe derive analytic expressions for temperature dependent absorption spectra as\nprobed by ferromagnetic resonance (FMR). By analysing the resulting\nexpressions, we can predict the variation of the resonance frequency and\ndamping with temperature and coupling to the thermal bath. We base our\ncalculations on the technologically relevant L1$_0$ FePt, parameterised from\natomistic spin dynamics simulations, with the Hamiltonian mapped from ab-initio\nparameters. By constructing a multi-macrospin model based on the LLB equation\nand exploiting GPU acceleration we extend the study to investigate the effects\non the damping and resonance frequency in ${\\mu}$m sized structures."
    },
    {
        "anchor": "Highly Efficient Ion Rejection by Graphene Oxide Membranes via\n  Ion-controlling Interlayer Spacing: Because they may provide ultrathin, high-flux, and energy-efficient membranes\nfor precise ionic and molecular sieving in aqueous solution, GO membranes\n(partially oxidized, stacked sheets of graphene) have shown great potential in\nwater desalination and purification, gas and ion separation, biosensors, proton\nconductors, lithium-based batteries and super-capacitors. Unlike carbon\nnanotube (CNT) membranes, in which the nanotube pores have fixed sizes, the\npores of GO membranes - the interlayer spacing between GO sheets - are of\nvariable size. This presents a challenge for using GO membranes for filtration.\nDespite the great efforts to tune and fix the interlayer spacing, it remains\ndifficult both to reduce the interlayer spacing sufficiently to exclude small\nions while keeping this separation constant against the tendency of GO\nmembranes to swell when immersed in aqueous solution, which greatly affects the\napplications of GO membranes. Here, we demonstrate experimentally that highly\nefficient and selective ion rejection by GO membranes can be readily achieved\nby controlling the interlayer spacing of GO membranes using cations (K+, Na+,\nCa2+, Li+ and Mg2+) themselves. The interspacing can be controlled with\nprecision as small as 1 A, and GO membranes controlled by one kind of cation\ncan exclude other cations with a larger hydrated volume, which can only be\naccommodated with a larger interlayer spacing. First-principles calculations\nreveal that the strong noncovalent cation-pi interactions between hydrated\ncations in solution and aromatic ring structures in GO are the cause of this\nunexpected behavior. These findings open up new avenues for using GO membranes\nfor water desalination and purification, lithium-based batteries and\nsuper-capacitors, molecular sieves for separating ions or molecules, and many\nother applications.",
        "positive": "Electrical Spin Injection in a Ferromagnetic / Tunnel Barrier/\n  Semiconductor Heterostructure: We demonstrate experimentally the electrical ballistic electron spin\ninjection from a ferromagnetic metal / tunnel barrier contact into a\nsemiconductor III-V heterostructure. We introduce the Oblique Hanle Effect\ntechnique for reliable optical measurement of the degree of injected spin\npolarization. In a CoFe / Al2O3 / GaAs / (Al,Ga)As heterostructure we observed\ninjected spin polarization in excess of 8 % at 80K."
    },
    {
        "anchor": "Negative Poisson's ratios in few-layer orthorhombic arsenic from\n  first-principles calculations: A material exhibiting a negative Poisson's ratio is always one of the leading\ntopics in materials science, which is due to the potential applications in\nthose special areas such as defence and medicine. In this letter, we\ndemonstrate a new material, few-layer orthorhombic arsenic, also possesses the\nnegative Poisson's ratio. For monolayer arsenic, the negative Poisson's ratio\nis predicted to be around -0.09, originated from the hinge-like structure\nwithin the single layer of arsenic. When the layer increases, the negative\nPoisson's ratio becomes more negative and finally approaches the limit at\nfour-layer, which is very close to the bulk's value of -0.12. The underlying\nmechanism is proposed for this layer-dependent negative Poisson's ratio, where\nthe internal bond lengths as well as the normal Poisson's ratio within layer\nplay a key role. The study like ours sheds new light on the physics of negative\nPoisson's ratio in those hinge-like nano-materials.",
        "positive": "Temperature-induced barium de-trapping from a double-well potential in\n  Ba6Ge25: The crystal structure of barium-germanium clathrate Ba6Ge25 was studied using\nneutron powder diffraction in the temperature range 20-300K. The compound was\nfound to be cubic (S.G. P4_1 23) in the entire temperature range. However, the\nfully-ordered model of the crystal structure (no split sites) is marginal at\nroom temperature, and clearly fails at low temperature. A much better\ndescription of the crystal structure below 250K is given in terms of two split\nBa sites, with random occupancies, for two out of three types of cages present\nin the Ba6Ge25 structure. The Ba atoms were found to interact strongly with the\nGe host. The separation of the split Ba sites grows with decreasing\ntemperature, with a sudden increase on cooling through the 200-250K temperature\nrange, accompanied by an expansion of the entire crystal structure. We propose\na simple model for this transition, based on temperature-induced de- trapping\nof Ba from a deep double-well potential. This transition is associated with\nsizeable anomalies in the transport and magnetic properties. The most\nsignificant of these effects, that is, the drop in electrical conductivity on\ncooling, can be easily explained within our model through the enhanced\nstructural disorder, which would affect the relaxation time for all portions of\nthe Fermi surface. We suggest that the other anomalies (increase in the\nabsolute value of the negative Seebeck coefficient, decrease in the magnetic\nsusceptibility) can be explained within the framework of the one-electron semi-\nclassical model, without any need to invoke exotic electron-electron\ninteraction mechanisms."
    },
    {
        "anchor": "Adiabatic measurements of magneto-caloric effects in pulsed high\n  magnetic fields up to 55 T: Magneto-caloric effects (MCEs) measurement system in adiabatic condition is\nproposed to investigate the thermodynamic properties in pulsed magnetic fields\nup to 55 T. With taking the advantage of the fast field- sweep rate in pulsed\nfield, adiabatic measurements of MCEs were carried out at various temperatures.\nTo obtain the prompt response of the thermometer in the pulsed field, a thin\nfilm thermometer is grown directly on the sample surfaces. The validity of the\npresent setup was demonstrated in the wide temperature range through the\nmeasurements on Gd at about room temperature and on Gd3Ga5O12 at low\ntemperatures. The both results show reasonable agreement with the data reported\nearlier. By comparing the MCE data with the specific heat data, we could\nestimate the entropy as functions of magnetic field and temperature. The\nresults demonstrate the possibility that our approach can trace the change in\ntransition temperature caused by the external field.",
        "positive": "Spin-ordering and magnetoelastic coupling in the extended Kagome system\n  YBaCo4O7: Low temperature magnetic and structural behavior of the extended Kagome\nsystem YBaCo4O7 has been studied by single crystal neutron diffraction and\nhigh-resolution powder X-ray diffraction. Long-range magnetic ordering\nassociated with a structural transition from orthorhombic Pbn2_1 to monoclinic\nP2_1 symmetry has been found at T_1 ~ 100 K. The interplay between the\nstructural and magnetic degrees of freedom testifies that the degeneracy of the\nmagnetic ground state, present in the orthorhombic phase, is lifted through a\nstrong magnetoelastic coupling, as observed in other frustrated systems. At T_2\n~ 60 K, an additional magnetic transition is observed, though iso-symmetric.\nModels for the magnetic structures below T_1 and T_2 are presented, based on\nrefinements using a large number of independent reflections. The results\nobtained are compared with previous single crystal and powder diffraction\nstudies on this and related compositions."
    },
    {
        "anchor": "Atomic engineering of interfacial polarization switching in van der\n  Waals multilayers: In conventional ferroelectric materials, polarization is an intrinsic\nproperty limited by bulk crystallographic structure and symmetry. Recently, it\nhas been demonstrated that polar order can also be accessed using inherently\nnon-polar van der Waals materials through layer-by-layer assembly into\nheterostructures, wherein interfacial interactions can generate spontaneous,\nswitchable polarization. Here, we show that introducing interlayer rotations in\nmultilayer vdW heterostructures modulates both the spatial ordering and\nswitching dynamics of polar domains, engendering unique tunability that is\nunparalleled in conventional bulk ferroelectrics or polar bilayers. Using\noperando transmission electron microscopy we show how changing the relative\nrotations of three WSe2 layers produces structural polytypes with distinct\narrangements of polar domains, leading to either a global or localized\nswitching response. Introducing uniaxial strain generates structural anisotropy\nthat yields a range of switching behaviors, coercivities, and even tunable\nbiased responses. We also provide evidence of physical coupling between the two\ninterfaces of the trilayer, a key consideration for controlling switching\ndynamics in polar multilayer structures more broadly.",
        "positive": "Capturing electronic correlations in electron-phonon interactions in\n  molecular systems with the GW approximation: Electron-phonon interactions are of great importance to a variety of physical\nphenomena, and their accurate description is an important goal for\nfirst-principles calculations. Isolated examples of materials and molecular\nsystems have emerged where electron-phonon coupling is enhanced over density\nfunctional theory (DFT) when using the Green's-function-based ab initio GW\nmethod, which provides a more accurate description of electronic correlations.\nIt is however unclear how general this enhancement is, and how employing\nhigh-end quantum chemistry methods, which further improve the description of\nelectronic correlations, might further alter electron-phonon interactions over\nGW or DFT. Here, we address these questions by computing the renormalization of\nthe highest occupied molecular orbital energies of Thiel's set of organic\nmolecules by harmonic vibrations using DFT, GW and equation-of-motion\ncoupled-cluster calculations. We find that GW can increase the magnitude of the\nelectron-phonon coupling across this set of molecules by an average factor of\n1.1-1.8 compared to DFT, while equation-of-motion coupled-cluster leads to an\nincrease of 1.4-2. The electron-phonon coupling predicted with the ab initio GW\nmethod is generally in much closer agreement to coupled cluster values compared\nto DFT, establishing GW as an accurate way of computing electron-phonon\nphenomena in molecules and beyond at a much lower computational cost than\nhigher-end quantum chemistry techniques."
    },
    {
        "anchor": "Unraveling the Interplay between Quantum Transport and Geometrical\n  Conformations in Monocyclic Hydrocarbons Molecular Junctions: In the field of molecular electronics, particularly in quantum transport\nstudies, the orientation of molecules plays a crucial role. This orientation,\nwith respect to the electrodes, can be defined through the cavity of\nring-shaped monocyclic hydrocarbon molecules. In this manuscript, we unveil the\ngeometrical conformation of these molecules when they are trapped between two\natomically sharp electrodes through a combination of dynamic simulations,\nelectronic transport calculations based on density functional theory, and break\njunction experiments under room conditions. Moreover, we present a novel\ncriterion for determining the molecular orientation of benzene, toluene,\n(aromatic) and cyclohexane (aliphatic) solvents. Our findings for the\nidentification of the molecular orientations on gold metal nanocontacts and\ntheir associated transport properties, can improve the understanding of\nmolecular electronics using more complex cyclic hydrocarbons.",
        "positive": "Preferential orientation of NV defects in CVD diamond films grown on\n  (113) substrates: Thick CVD diamond layers were successfully grown on (113)-oriented\nsubstrates. They exhibited smooth surface morphologies and a crystalline\nquality comparable to (100) electronic grade material, and much better than\n(111)-grown layers. High growth rates (15-50 {\\mu}m/h) were obtained while\nnitrogen doping could be achieved in a fairly wide range without seriously\nimparting crystalline quality. Electron spin resonance measurements were\ncarried out to determine NV centers orientation and concluded that one specific\norientation has an occurrence probability of 73 % when (100)-grown layers show\nan equal distribution in the 4 possible directions. A spin coherence time of\naround 270 {\\mu}s was measured which is equivalent to that reported for\nmaterial with similar isotopic purity. Although a higher degree of preferential\norientation was achieved with (111)-grown layers (almost 100 %), the ease of\ngrowth and post-processing of the (113) orientation make it a potentially\nuseful material for magnetometry or other quantum mechanical applications."
    },
    {
        "anchor": "Collapse of the Electron Gas to Two Dimensions in Density Functional\n  Theory: Local and semilocal density-functional approximations for the\nexchange-correlation energy fail badly in the zero-thickness limit of a\nquasi-two-dimensional electron gas, where the density variation is rapid almost\neverywhere. Here we show that a fully nonlocal fifth-rung functional, the\ninhomogeneous Singwi-Tosi-Land-Sj\\\"olander (STLS) approach, which employs both\noccupied and unoccupied Kohn-Sham orbitals, recovers the true two-dimensional\nSTLS limit and appears to be remarkably accurate for any thickness of the slab\n(and thus for the dimensional crossover). We also show that this good behavior\nis only partly due to the use of the full exact exchange energy.",
        "positive": "Anomalous Hall Effect in Fe/Gd Bilayers: Non-monotonic dependence of anomalous Hall resistivity on temperature and\nmagnetization, including a sign change, was observed in Fe/Gd bilayers. To\nunderstand the intriguing observations, we fabricated the Fe/Gd bilayers and\nsingle layers of Fe and Gd simultaneously. The temperature and field\ndependences of longitudinal resistivity, Hall resistivity and magnetization in\nthese films have also been carefully measured. The analysis of these data\nreveals that these intriguing features are due to the opposite signs of Hall\nresistivity/or spin polarization and different Curie temperatures of Fe and Gd\nsingle-layer films."
    },
    {
        "anchor": "Role of defects and disorder in the half-metallic full-Heusler compounds: Half-metallic ferromagnets and especially the full-Heusler alloys containing\nCo are at the center of scientific research due to their potential applications\nin spintronics. For realistic devices it is important to control accurately the\ncreation of defects in these alloys. We review some of our late results on the\nrole of defects and impurities in these compounds. More precisely we present\nresults for the following cases (i) doping and disorder in Co$_2$Cr(Mn)Al(Si)\nalloys, (ii) half-metallic ferrimagnetism appeared due to the creation of\nCr(Mn) antisites in these alloys, (iii) Co-doping in Mn$_2$VAl(Si) alloys\nleading to half-metallic antiferromagnetism, and finally (iv) the occurrence of\nvacancies in the full-Heusler alloys containing Co and Mn. These results are\nsusceptible of encouraging further theoretical and experimental research in the\nproperties of these compounds.",
        "positive": "Stoichiometric Control and Optical Properties of BaTiO3 Thin Films Grown\n  by Hybrid MBE: BaTiO3 is a technologically relevant material in the perovskite oxide class\nwith above room temperature ferroelectricity and a very large electro optical\ncoefficient, making it highly suitable for emerging electronic and photonic\ndevices. An easy, robust, straightforward, and scalable growth method is\nrequired to synthesize epitaxial BaTiO3 thin films with sufficient control over\nthe film stoichiometry to achieve reproducible thin film properties. Here we\nreport the growth of BaTiO3 thin films by hybrid molecular beam epitaxy. A self\nregulated growth window is identified using complementary information obtained\nfrom reflection high energy electron diffraction, the intrinsic film lattice\nparameter, film surface morphology, and scanning transmission electron\nmicroscopy. Subsequent optical characterization of the BaTiO3 films by\nspectroscopic ellipsometry revealed refractive index and extinction coefficient\nvalues closely resembling those of stoichiometric bulk BaTiO3 crystals for\nfilms grown inside the growth window. Even in the absence of a lattice\nparameter change of BaTiO3 thin films, degradation of optical properties was\nobserved, accompanied by the appearance of a wide optical absorption peak in\nthe infrared spectrum, attributed to optical transitions involving defect\nstates present. Therefore, the optical properties of BaTiO3 can be utilized as\na much finer and more straightforward probe to determine the stoichiometry\nlevel present in BaTiO3 films."
    },
    {
        "anchor": "Spontaneous formation of Frenkel defects in high-entropy-alloys-type\n  compound: High-entropy alloys (HEAs) are attracting attention due to their exceptional\nproperties, such as enhanced mechanical toughness, superconducting robustness,\nand thermoelectric performance. Numerous HEAs have been developed for diverse\napplications, ranging from self-healing in fusion reactors to addressing\nenvironmental concerns with thermoelectric materials. Understanding atomic\ndiffusion within HEA crystals is crucial for these applications. Here, this\nstudy investigates diffusion mechanisms in PbTe-based HEAs, focusing on the\nrole of indium (In). Molecular dynamics simulations reveal that In inclusion\nprompts spontaneous Frenkel defect formation, notably enhancing diffusion not\nonly of In$^+$ but also other cations. Frenkel defect formation, closely linked\nto alloy properties, is predominantly influenced by charge rather than cation\nsize. This insight not only enhances comprehension of HEA diffusion mechanisms\nbut also develops HEAs with properties such as self-healing from damage and\nhigh ion permeability, advancing the field of material science.",
        "positive": "Simulation of Arsenic Diffusion During Rapid Thermal Annealing of\n  Silicon Layers Doped with Low-Energy High-Dose Ion Implantation: The model of transient enhanced diffusion of ion-implanted As is formulated\nand the finite-difference method for numerical solution of the system of\nequations obtained is developed. The nonuniform distribution of point defects\nnear the interface and more accurate description of arsenic clustering are\nsimultaneously taking into account. Simulation of As diffusion during rapid\nannealing gives a reasonable agreement with the experimental data.\n  Keywords: diffusion; clusters; ion implantation; arsenic; silicon\n  PACS: 66.30.Jt"
    },
    {
        "anchor": "An Automated Scanning Transmission Electron Microscope Guided by Sparse\n  Data Analytics: Artificial intelligence (AI) promises to reshape scientific inquiry and\nenable breakthrough discoveries in areas such as energy storage, quantum\ncomputing, and biomedicine. Scanning transmission electron microscopy (STEM), a\ncornerstone of the study of chemical and materials systems, stands to benefit\ngreatly from AI-driven automation. However, present barriers to low-level\ninstrument control, as well as generalizable and interpretable feature\ndetection, make truly automated microscopy impractical. Here, we discuss the\ndesign of a closed-loop instrument control platform guided by emerging sparse\ndata analytics. We demonstrate how a centralized controller, informed by\nmachine learning combining limited $a$ $priori$ knowledge and task-based\ndiscrimination, can drive on-the-fly experimental decision-making. This\nplatform unlocks practical, automated analysis of a variety of material\nfeatures, enabling new high-throughput and statistical studies.",
        "positive": "Optical Limiting in Single-walled Carbon Nanotube Suspensions: Optical limiting behaviour of suspensions of single-walled carbon nanotubes\nin water, ethanol and ethylene glycol is reported. Experiments with 532 nm, 15\nnsec duration laser pulses show that optical limiting occurs mainly due to\nnonlinear scattering. The observed host liquid dependence of optical limiting\nin different suspensions suggests that the scattering originates from\nmicrobubbles formed due to absorption-induced heating."
    },
    {
        "anchor": "A model for retention on short, intermediate and long time-scale in\n  ferroelectric thin films: We developed a model with no adjustable parameter for retention loss at short\nand long time scale in ferroelectric thin-film capacitors. We found that the\npredictions of this model are in good agreement with the experimental\nobservations in the literature. In particular, it explains why a power-law\nfunction shows better fitting than a linear-log relation on a short time scale\n(10^-7 s to 1 s) and why a stretched exponential relation gives more precise\ndescription than a linear-log plot on a long time scale (>100 s), as reported\nby many researchers in the past. More severe retention losses at higher\ntemperatures and in thinner films have also been correctly predicted by the\npresent theory.",
        "positive": "Influence of aggregate size and volume fraction on shrinkage induced\n  micro-cracking of concrete and mortar: In this paper, the influence of aggregate size and volume fraction on\nshrinkage induced micro-cracking and permeability of concrete and mortar was\ninvestigated. Nonlinear finite element analyses of model concrete and mortar\nspecimens with regular and random aggregate arrangements were performed. The\naggregate diameter was varied between 2 and 16 mm. Furthermore, a range of\nvolume fractions between 0.1 and 0.5 was studied. The nonlinear analyses were\nbased on a 2D lattice approach in which aggregates were simplified as monosized\ncylindrical inclusions. The analysis results were interpreted by means of crack\nlength, crack width and change of permeability. The results show that\nincreasing aggregate diameter (at equal volume fraction) and decreasing volume\nfraction (at equal aggregate diameter), increases crack width and consequently\ngreatly increases permeability."
    },
    {
        "anchor": "Pressure-driven switching of magnetism in layered CrCl3: Layered transition-metal compounds with controllable magnetic behaviors\nprovide many fascinating opportunities for the fabrication of high-performance\nmagneto-electric and spintronic devices. The tuning of their electronic and\nmagnetic properties is usually limited to the change of layer thickness,\nelectrostatic doping, and the control of electric and magnetic fields. However,\npressure has been rarely exploited as a control parameter for tailoring their\nmagneto-electric properties. Here, we report a unique pressure-driven\nisostructural phase transition in layered CrCl3 accompanied by a simultaneous\nswitching of magnetism from a ferromagnetic to an antiferromagnetic ordering.\nOur experiments, in combination with ab initio calculations, demonstrate that\nsuch a magnetic transformation hinders the band-gap collapse under pressure,\nleading to an anomalous semiconductor-to-semiconductor transition. Our findings\nnot only reveal high potential of CrCl3 in electronic and spintronic\napplications under ambient and extreme conditions but also establish the basis\nfor exploring unusual phase transitions in layered transition-metal compounds.",
        "positive": "X-ray circular dichroism versus orbital magnetization: The x-ray magnetic circular dichroism (XMCD) sum rule yields an extremely\nuseful ground-state observable, which provides a quantitative measure of\nspontaneous time-reversal symmetry breaking (T-breaking) in a given material. I\nderive here its explicit expression within band-structure theory, in the\ngeneral case: trivial insulators, topological insulators, and metals. Orbital\nmagnetization provides a different measure of T-breaking in the electronic\nground state. The two observables belong to the class of \"geometrical\"\nobservables; both are local and admit a \"density\" in coordinate space. In both\nof them one could include/exclude selected groups of bands, in order to acquire\nelement-specific information about the T-breaking material. Only in the case of\nan isolated flat band the contributions to the two observables coincide.\nFinally, I provide the corresponding geometrical formula-in a different Hilbert\nspace-for a many-body interacting system."
    },
    {
        "anchor": "Zone-Center Dynamical Matrix in Magnetoelectrics: In ordinary dielectrics the dynamical matrix at the zone center in general is\na nonanalytic function of degree zero in the wavevector q. Its expression (for\na crystal of arbitrary symmetry) is well known and is routinely implemented in\nfirst principle calculations. The nonanalytic behavior occurs in polar crystals\nand owes to the coupling of the macroscopic electric field E to the lattice. In\nmagnetoelectric crystals both electric and magnetic fields, E and H, are\ncoupled to the lattice, formally on equal footing. We provide the general\nexpression for the zone center dynamical matrix in a magnetoelectric, where the\nE and H couplings are accounted for in a symmetric way. As in the ordinary\ncase, the dynamical matrix is a nonanalytic function of degree zero in q, and\nis exact in the harmonic approximation. For the sake of completeness, we\naddress other issues, and in particular we solve a problem which might arise in\nfirst-principle implementations, where-differently than here-the basic fields\nare E and B (not H).",
        "positive": "Rebound indentation problem for a viscoelastic half-space and\n  axisymmetric indenter - Solution by the method of dimensionality reduction: The method of dimensionality reduction (MDR) is extended for the axisymmetric\nfrictionless unilateral Hertz-type contact problem for a viscoelastic\nhalf-space and an arbitrary axisymmetric rigid indenter under the assumption\nthat an arbitrarily evolving in time circular contact area remains singly\nconnected during the whole process of indentation. In particular, the MDR is\napplied to study in detail the so-called rebound indentation problem, where the\ncontact radius has a single maximum. It is shown that the obtained closed-form\nanalytical solution for the rebound indentation displacement (recorded in the\nrecovery phase, when the contact force vanishes) does not depend on the\nindenter shape."
    },
    {
        "anchor": "Roughness-induced magnetic decoupling at organic-inorganic interface: We have investigated structural, electronic and magnetic properties of\nH$_2$Pc on Fe$_2$N/Fe using low-energy electron diffraction and soft x-ray\nabsorption spectroscopy/x-ray magnetic circular dichroism. Element specific\nmagnetization curves reveal that the magnetic coupling with H$_2$Pc enhances\nthe perpendicular magnetic anisotropy of Fe$_2$N/Fe at the H$_2$Pc coverage of\n1 molecular layer. However, adding two and three molecular layers of H$_2$Pc\nreverts the shape of magnetization curve back to the initial state before\nH$_2$Pc deposition. We successfully link appearance and disappearance of the\nmagnetic coupling at the H$_2$Pc-Fe$_2$N/Fe interface with the change of\nhybridization strength at N sites accompanied by the increase in the H$_2$Pc\ncoverage.",
        "positive": "Graphdiyne-metal contacts and graphdiyne transistors: Graphdiyne is prepared on metal surface, and making devices out of it also\ninevitably involves contact with metals. Using density functional theory with\ndispersion correction, we systematically studied for the first time the\ninterfacial properties of graphdiyne contacting with a series of metals (Al,\nAg, Cu, Au, Ir, Pt, Ni, and Pd). Graphdiyne is in an n-type Ohmic or\nquasi-Ohmic contact with Al, Ag, and Cu, while it is in a Schottky contact with\nAu (at source/drain interface), Pd, Pt, Ni, and Ir (at source/drain-channel\ninterface), with high Schottky barrier heights of 0.39, 0.21 (n-type), 0.30,\n0.41, and 0.45 (p-type) eV, respectively. A graphdiyne field effect transistor\n(FET) with Al electrodes is simulated by using quantum transport calculations.\nThis device exhibits an on-off ratio up to 104 and a very large on-state\ncurrent of 1.3 * 104 mA/mm in a 10 nm channel length. Thus, a new prospect is\nopened up for graphdiyne in high performance nanoscale devices."
    },
    {
        "anchor": "Non-perturbative high-harmonic generation in the three-dimensional Dirac\n  semimetal Cd$_3$As$_2$: Harmonic generation is a general characteristic of driven nonlinear systems,\nand serves as an efficient tool for investigating the fundamental principles\nthat govern the ultrafast nonlinear dynamics. In atomic gases, high-harmonic\nradiation is produced via a three-step process of ionization, acceleration, and\nrecollision by strong-field infrared laser. This mechanism has been intensively\ninvestigated in the extreme ultraviolet and soft X-ray regions, forming the\nbasis of attosecond research. In solid-state materials, which are characterized\nby crystalline symmetry and strong interactions, yielding of harmonics has just\nrecently been reported. The observed high-harmonic generation was interpreted\nwith fundamentally different mechanisms, such as interband tunneling combined\nwith dynamical Bloch oscillations, intraband thermodynamics and nonlinear\ndynamics, and many-body electronic interactions. Here, in a distinctly\ndifferent context of three-dimensional Dirac semimetal, we report on\nexperimental observation of high-harmonic generation up to the seventh order\ndriven by strong-field terahertz pulses. The observed non-perturbative\nhigh-harmonic generation is interpreted as a generic feature of terahertz-field\ndriven nonlinear intraband kinetics of Dirac fermions. We anticipate that our\nresults will trigger great interest in detection, manipulation, and coherent\ncontrol of the nonlinear response in the vast family of three-dimensional Dirac\nand Weyl materials.",
        "positive": "Non-Fourier heat transport in metal-dielectric core-shell nanoparticles\n  under ultrafast laser pulse excitation: Relaxation dynamics of embedded metal nanoparticles after ultrafast laser\npulse excitation is driven by thermal phenomena of different origins the\naccurate description of which is crucial for interpreting experimental results:\nhot electron gas generation, electron-phonon coupling, heat transfer to the\nparticle environment and heat propagation in the latter. Regardingthis last\nmechanism, it is well known that heat transport in nanoscale structures and/or\nat ultrashort timescales may deviate from the predictions of the Fourier law.\nIn these cases heat transport may rather be described by the Boltzmann\ntransport equation. We present a numerical model allowing us to determine the\nelectron and lattice temperature dynamics in a spherical gold nanoparticle core\nunder subpicosecond pulsed excitation, as well as that of the surrounding shell\ndielectric medium. For this, we have used the electron-phonon coupling equation\nin the particle with a source term linked with the laser pulse absorption, and\nthe ballistic-diffusive equations for heat conduction in the host medium.\nEither thermalizing or adiabatic boundary conditions have been considered at\nthe shell external surface. Our results show that the heat transfer rate from\nthe particle to the matrix can be significantly smaller than the prediction of\nFourier's law. Consequently, the particle temperature rise is larger and its\ncooling dynamics might be slower than that obtained by using Fourier's law.\nThis difference is attributed to the nonlocal and nonequilibrium heat\nconduction in the vicinity of the core nanoparticle. These results are expected\nto be of great importance for analyzing pump-probe experiments performed on\nsingle nanoparticles or nanocomposite media."
    },
    {
        "anchor": "Impact of anharmonicity on sound wave velocities at extreme conditions: Theoretical calculations of sound-wave velocities of materials at extreme\nconditions are of great importance to various fields, in particular geophysics.\nFor example, the seismic data on sound-wave propagation through the solid\niron-rich Earth's inner core have been the main source for elucidating its\nproperties and building models. As the laboratory experiments at very high\ntemperatures and pressures are non-trivial, ab initio predictions are\ninvaluable. The latter, however, tend to disagree with experiment. We notice\nthat many attempts to calculate sound-wave velocities of matter at extreme\nconditions in the framework of quantum-mechanics based methods have not been\ntaking into account the effect of anharmonic atomic vibrations. We show how\nanharmonic effects can be incorporated into ab initio calculations and\ndemonstrate that in particular they might be non-negligible for iron in Earth's\ncore. Therefore, we open an avenue to reconcile experiment and ab initio\ntheory.",
        "positive": "Low Losses Left Handed Materials Using Metallic Magnetic Cylinders: We discuss materials based on arrays of metallic magnetic cylindrical\nstructures near ferromagnetic resonance with applied magnetic fields at\nmicrowave frequencies. We have found that the materials have a negative\nrefraction index when the appropriate structure is chosen. Numerical FDTD\nsimulations were performed, after a very large number of geometries were swept.\nThe simulations reveal that only ferromagnetic cylinders, with diameters of 0.1\ncm and 0.5 cm apart, and with periodic or random configurations, are\nleft-handed materials with very small losses; i.e. with transmitivity\npractically unity or no losses."
    },
    {
        "anchor": "Optical Phonon Limited High Field Transport in Layered Materials: An optical phonon limited velocity model has been employed to investigate\nhigh-field transport in a selection of layered 2D materials for both, low-power\nlogic switches with scaled supply voltages, and high-power, high-frequency\ntransistors. Drain currents, effective electron velocities and intrinsic\ncut-off frequencies as a function of carrier density have been predicted thus\nproviding a benchmark for the optical phonon limited high-field performance\nlimits of these materials. The optical phonon limited carrier velocities of a\nselection of transition metal dichalcogenides and black phosphorus are found to\nbe modest as compared to their n-channel silicon counterparts, questioning the\nutility of these devices in the source-injection dominated regime. h-BN, at the\nother end of the spectrum, is shown to be a very promising material for\nhigh-frequency high-power devices, subject to experimental realization of high\ncarrier densities, primarily due to its large optical phonon energy.\nExperimentally extracted saturation velocities from few-layer MoS2 devices show\nreasonable qualitative and quantitative agreement with predicted values.\nTemperature dependence of measured vsat is discussed and found to fit a\nvelocity saturation model with a single material dependent fit parameter.",
        "positive": "Lifshitz transition mediated electronic transport anomaly in bulk ZrTe5: Zirconium pentatelluride ZrTe$_5$, a fascinating topological material\nplatform, hosts exotic chiral fermions in its highly anisotropic\nthree-dimensional Dirac band and holds great promise advancing the\nnext-generation information technology. However, the origin underlying its\nanomalous resistivity peak has been under debate for decades. Here we provide\ntransport evidence substantiating the anomaly to be a direct manifestation of a\nLifshitz transition in the Dirac band with an ultrahigh carrier mobility\nexceeding 3$\\times$10$^5$ cm$^2$ V$^{-1}$ s$^{-1}$. We demonstrate that the\nLifshitz transition is readily controllable by means of carrier doping, which\nsets the anomaly peak temperature $T_p$. $T_p$ is found to scale approximately\nas $n_H^{0.27}$, where the Hall carrier concentration $n_H$ is linked with the\nFermi level by $\\epsilon_F$ $\\propto$ $n_H^{1/3}$ in a linearly dispersed Dirac\nband. This relation indicates $T_p$ monotonically increases with $\\epsilon_F$,\nwhich serves as an effective knob for fine tuning transport properties in\npentatelluride-based Dirac semimetals."
    },
    {
        "anchor": "Phase Space Sketching for Crystal Image Analysis based on\n  Synchrosqueezed Transforms: Recent developments of imaging techniques enable researchers to visualize\nmaterials at the atomic resolution to better understand the microscopic\nstructures of materials. This paper aims at automatic and quantitative\ncharacterization of potentially complicated microscopic crystal images,\nproviding feedback to tweak theories and improve synthesis in materials\nscience. As such, an efficient phase-space sketching method is proposed to\nencode microscopic crystal images in a translation, rotation, illumination, and\nscale invariant representation, which is also stable with respect to small\ndeformations. Based on the phase-space sketching, we generalize our previous\nanalysis framework for crystal images with simple structures to those with\ncomplicated geometry.",
        "positive": "Time-resolved observation of fast domain-walls driven by vertical spin\n  currents in short tracks: We present time-resolved measurements of the displacement of magnetic\ndomain-walls (DWs) driven by vertical spin-polarized currents in track-shaped\nmagnetic tunnel junctions. In these structures we observe very high DW\nvelocities (600 m/s) at current densities below $10^7 A/cm^2$. We show that the\nefficient spin-transfer torque combined with a short propagation distance\nallows to avoid the Walker breakdown process, and achieve deterministic,\nreversible and fast ($\\approx$ 1 ns) DW-mediated switching of magnetic tunnel\njunction elements, which is of great interest to the implementation of fast\nDW-based spintronic devices."
    },
    {
        "anchor": "Preparation of carbon nanotubes from graphite powder at room temperature: We develop a new chemical route to prepare carbon nanotubes at room\ntemperature. Graphite powder is immersed in a mixed solution of nitric and\nsulfuric acid with potassium chlorate. After heating the solution up to\n70{\\deg}C and leaving them in the air for 3 days, we obtained carbon nanotube\nbundles. This process could provide an easy and inexpensive method for the\npreparation of carbon nanotubes.",
        "positive": "Ultrafast reduction of exchange splitting in ferromagnetic nickel: A decade ago Rhie \\et (Phys. Rev. Lett. {\\bf 90}, 247201 (2003)) reported\nthat when ferromagnetic nickel is subject to an intense ultrashort laser pulse,\nits exchange splitting is reduced quickly. But to simulate such reduction\nremains a big challenge. The popular rigid band approximation (RBA), where both\nthe band structure and the exchange splitting are held fixed before and after\nlaser excitation, is unsuitable for this purpose, while the time-dependent\ndensity functional theory could be time-consuming. To overcome these\ndifficulties, we propose a time-dependent Liouville and density functional\ntheory (TDLDFT) that integrates the time-dependent Liouville equation into the\ndensity functional theory. As a result, the excited charge density is\nreiterated back into the Kohn-Sham equation, and the band structure is allowed\nto change dynamically. Even with the ground-state density functional, a larger\ndemagnetization than RBA is found; after we expand Ortenzi's spin scaling\nmethod into an excited-state (laser) density functional, we find that the\nexchange splitting is indeed strongly reduced, as seen in the experiment. Both\nthe majority and minority bands are shifted toward the Fermi level, but the\nmajority shifts a lot more. The ultrafast reduction in exchange splitting\noccurs concomitantly with demagnetization. While our current theory is still\nunable to yield the same percentage loss in the spin moment as observed in the\nexperiment, it predicts a correct trend that agrees with the experiments. With\na better functional, we believe that our results can be further improved."
    },
    {
        "anchor": "A physics-based life prediction methodology for thermal barrier coating\n  systems: A novel mechanistic approach is proposed for the prediction of the life of\nthermal barrier coating (TBC) systems. The life prediction methodology is based\non a criterion linked directly to the dominant failure mechanism. It relies on\na statistical treatment of the TBC's morphological characteristics,\nnon-destructive stress measurements and on a continuum mechanics framework to\nquantify the stresses that promote the nucleation and growth of microcracks\nwithin the TBC. The last of these accounts for the effects of TBC constituents'\nelasto-visco-plastic properties, the stiffening of the ceramic due to sintering\nand the oxidation at the interface between the thermally insulating yttria\nstabilized zirconia (YSZ) layer and the metallic bond coat. The mechanistic\napproach is used to investigate the effects on TBC life of the properties and\nmorphology of the top YSZ coating, metallic low-pressure plasma sprayed bond\ncoat and the thermally grown oxide. Its calibration is based on TBC damage\ninferred from non-destructive fluorescence measurements using\npiezo-spectroscopy and on the numerically predicted local TBC stresses\nresponsible for the initiation of such damage. The potential applicability of\nthe methodology to other types of TBC coatings and thermal loading conditions\nis also discussed.",
        "positive": "Linear-response theory of the longitudinal spin Seebeck effect: We theoretically investigate the longitudinal spin Seebeck effect, in which\nthe spin current is injected from a ferromagnet into an attached nonmagnetic\nmetal in a direction parallel to the temperature gradient. Using the fact that\nthe phonon heat current flows intensely into the attached nonmagnetic metal in\nthis particular configuration, we show that the sign of the spin injection\nsignal in the longitudinal spin Seebeck effect can be opposite to that in the\nconventional transverse spin Seebeck effect when the electron-phonon\ninteraction in the nonmagnetic metal is sufficiently large. Our linear-response\napproach can explain the sign reversal of the spin injection signal recently\nobserved in the longitudinal spin Seebeck effect."
    },
    {
        "anchor": "Melting curve of magnesium up to 460 GPa from ab initio molecular\n  dynamics simulations: Based on ab initio molecular dynamics simulations, we determined the melting\ncurve of magnesium (Mg) up to ~460 GPa using the solid-liquid coexistence\nmethod. Between ~30 and 100 GPa, our melting curve is noticeably lower than\nthose from static experiments, but is in good agreement with recent shock\nexperiments. Up to ~450 GPa, our melting curve is generally consistent with the\nmelting points from first-principles calculations using the small-cell\ncoexistence method. We found that, at high pressures of a few hundred GPa, due\nto the strong softening of interatomic interactions in the liquid phase,\nsolid-liquid coexistence simulations of Mg show some characteristics\ndistinctively different from other metal systems, such as aluminum. For\nexample, at a given volume, the pressure and temperature range for maintaining\na stable solid-liquid coexistence state can be very small. The strong softening\nin the liquid phase also causes the unusual behavior of reentrant melting to\noccur at very high pressures. The onset of reentrant melting is predicted at\n~305 GPa, close to that at ~300 GPa from the small-cell coexistence method. We\nshow that the calculated melting points, considering reentrant melting, can be\nexcellently fitted to a low-order Kechin equation, thereby making it possible\nfor us to obtain a first-principles melting curve of Mg at pressures above 50\nGPa for the first time. Similar characteristics in solid-liquid coexistence\nsimulations, as well as reentrant melting, are also expected for other systems\nwith strong softening in the liquid phase at high pressures.",
        "positive": "First-Principles Investigation of Anchoring Behavior of WS2 and WSe2 for\n  Lithium-Sulfur Batteries: The commercial realization of lithium-sulfur (Li-S) batteries is obstructed\nbecause of rapid capacity fading due to lithium polysulfides (LiPSs)\ndissolution into the electrolyte. In order to enhance the efficiency and\nperformance of the Li-S batteries, the transition metal dichalcogenides are\nreported as promising anchoring materials (AMs) as they could strongly adsorb\nand effectively suppress the migration of the polysulfides species. Herein, we\nused first-principles based density functional theory (DFT) calculations to\ninvestigate the interactions between AMs such as tungsten dichalcogenides, WX2\n(X=S and Se) and the LiPSs. The LiPSs binding behavior of WS2 and WSe2 are\nfound to be quite similar. The calculated adsorption energies of LiPS species\nindicate that the WX2 possesses moderate binding strength and the binding is\nfacilitated via charge transfer from the polysulfides to the AM. We observe\nelongation of intramolecular Li-S bonds in LiPS upon their adsorption onto the\nWX2, however, chemical structures of LiPSs are preserved without decomposition.\nThe calculated density of states indicates the LiPS adsorbed WX2 systems\nexhibits semiconducting behavior with a slightly lower bandgap compared to the\npristine WX2. Overall, our simulation results provide detailed insight into the\nbehavior of WX2 as AMs to suppress the LiPSs migration and henceforth paves the\nway towards the development of high-performance Li-S batteries."
    },
    {
        "anchor": "Fano Resonances in Mid-Infrared Spectra of Single-Walled Carbon\n  Nanotubes: This work revisits the physics giving rise to the carbon nanotubes phonon\nbands in the mid- infrared. Our measurements of doped and undoped samples of\nsingle-walled carbon nanotubes in Fourier transform infrared spectroscopy show\nthat the phonon bands exhibit an asymmetric lineshape and that their effective\ncross-section is enhanced upon doping. We relate these observations to\nelectron-phonon coupling or, more specifically, to a Fano resonance phenomenon.\nWe note that only the dopant-induced intraband continuum couples to the phonon\nmodes and that defects induced in the sidewall increase the resonance\nprobabilities.",
        "positive": "Impurity induced enhancement of perpendicular magnetic anisotropy in\n  Fe/MgO tunnel junctions: Using first-principles calculations, we investigated the impact of chromium\n(Cr) and vanadium (V) impurities on the magnetic anisotropy and spin\npolarization in Fe/MgO magnetic tunnel junctions. It is demonstrated using\nlayer resolved anisotropy calculation technique, that while the impurity near\nthe interface has a drastic effect in decreasing the perpendicular magnetic\nanisotropy (PMA), its position within the bulk allows maintaining high surface\nPMA. Moreover, the effective magnetic anisotropy has a strong tendency to go\nfrom in-plane to out-of-plane character as a function of Cr and V concentration\nfavoring out-of-plane magnetization direction for ~1.5 nm thick Fe layers at\nimpurity concentrations above 20 %. At the same time, spin polarization is not\naffected and even enhanced in most situations favoring an increase of tunnel\nmagnetoresistance (TMR) values."
    },
    {
        "anchor": "Antiferromagnetic metal phases in double perovskites having strong\n  antisite defect concentrations: Recently an antiferromagnetic metal phase has been proposed in double\nperovskites materials like Sr$_{2}$FeMoO$_{6}$ (SFMO), when electron doped.\nThis material has been found to change from half-metallic ferromagnet to\nantiferromagnetic metal (AFM) upon La-overdoping. The original proposition of\nsuch an AFM phase was made for clean samples, but the experimental realization\nof La-overdoped SFMO has been found to contain a substantial fraction of\nantisite defects. A phase segregation into alternate Fe and Mo rich regions was\nobserved. In this paper we propose a possible scenario in which this type of\nstrong antisite concentration can still result in an antiferromagnetic metal\nphase, by a novel hopping driven mechanism. Using variational calculations, we\nfind that proliferation of such phase segregated domain regions can also result\nin the stabilization of an A-type AFM over the G-type AFM based on kinetic\nenergy considerations.",
        "positive": "Unzipping chemical bond of non-layered bulk structures to form ultrathin\n  nanocrystals: The rich electronic and band structures of monolayered crystals distinguished\nfrom their layered bulk counterparts offer versatile physical/chemical\nproperties and applications.1-5 Their fabrications, particularly the top-down\n\"exfoliations\", are successful promised by the weak Van der Waals force between\nmonolayers.6-9 Differentially, un-zipping ultra-thin crystals (e.g. with only\none layer of crystal plane) from non-layered structures is highly challenging\ndue to the strong chemical bond between planes and atoms. Alterative finely\ncontrolled growth of these ultra-thin materials is not really successful. This\nwork demonstrates how a technique can be used to unzip and disintegrate\nultra-thin crystal plane (e.g. monolayered nanocrystals and nanosheets) from\nbulk non-layered structures (ZnO, alpha/belta-MnO2, TiO2, alpha-TiB2), and\npresent how the basic optical properties changed to distinguish from their bulk\nphases. The work here gives a strong tool kit to various novel 2D non-layered\nnanomaterials, providing significant contributions to the family of\ntwo-dimensional materials, potentially paving the way for various practical\napplications."
    },
    {
        "anchor": "Spin-transfer torque in magnetic tunnel junctions: Scattering theory: We study the bias-dependent spin-transfer torque in magnetic tunnel junctions\nin the Stoner model by scattering theory. We show that the in-plane\n(Slonczewski type) torque vanishes and subsequently reverses its direction when\nthe bias voltage becomes larger or the barrier wider than material and\ndevice-dependent critical values. We are able to reproduce the magnitude and\nthe bias dependence of measured in-plane and out-of-plane torques using\nrealistic parameters. The condition for the vanishing torque is summarized by a\nphase diagram depending on the applied bias and barrier width, which is\nexplained in terms of an interface spin polarization and the electron focusing\nby the barrier. Quantum size effects in the spin-transfer torque are predicted\nas a function of the thickness of a normal metal layer inserted between the\nferromagnet and tunnel barrier.",
        "positive": "Diffusion of degenerate minority carriers in a p-type semiconductor: We report ultrafast transient-grating experiments on heavily p-type InP at 15\nK. Our measurement reveals the dynamics and diffusion of photoexcited electrons\nand holes as a function of their density n in the range 2E16 to 6E17 cm-3.\nAfter the first few picoseconds the grating decays primarily due to ambipolar\ndiffusion. While at low density we observe a regime in which the ambipolar\ndiffusion is electron-dominated and increases rapidly with n, at high n it\nappears to saturate at 34 cm2/s. We present a simple calculation that\nreproduces the main results of our measurements as well as of previously\npublished measurements that had shown diffusion to be a flat or decreasing\nfunction of n. By accounting for effect of density on charge susceptibility we\nshow that, in p-type semiconductors, the regime we observe of increasing\nambipolar diffusion is unique to heavy doping and low temperature, where both\nthe holes and electrons are degenerate; in this regime the electronic and\nambipolar diffusion are nearly equal. The saturation is identified as a\ncrossover to ambipolar diffusion dominated by the majority carriers, the holes.\nAt short times the transient-grating signal rises gradually. This rise reveals\ncooling of hot electrons and, at high photocarrier density, allows us to\nmeasure ambipolar diffusion of 110 cm2/s in the hot-carrier regime."
    },
    {
        "anchor": "Topological Dirac Nodal-net Fermions in AlB$_2$-type TiB$_2$ and ZrB$_2$: Based on first-principles calculations and effective model analysis, a Dirac\nnodal-net semimetal state is recognized in AlB$_2$-type TiB$_2$ and ZrB$_2$\nwhen spin-orbit coupling (SOC) is ignored. Taking TiB$_2$ as an example, there\nare several topological excitations in this nodal-net structure including\ntriple point, nexus, and nodal link, which are protected by coexistence of\nspatial-inversion symmetry and time reversal symmetry. This nodal-net state is\nremarkably different from that of IrF$_4$, which requires sublattice chiral\nsymmetry. In addition, linearly and quadratically dispersed two-dimensional\nsurface Dirac points are identified as having emerged on the B-terminated and\nTi-terminated (001) surfaces of TiB$_2$ respectively, which are analogous to\nthose of monolayer and bilayer graphene.",
        "positive": "Structural Properties, Impedance Spectroscopy and Dielectric Spin\n  Relaxation of Ni-Zn Ferrite Synthesized by Double Sintering Technique: Structural properties, impedance, dielectric and electric modulus spectra\nhave been used to investigate the sintering temperature (Ts) effect on the\nsingle phase cubic spinel Ni0.6Zn0.4Fe2O4 (NZFO) ceramics synthesized by\nstandard ceramic technique. Enhancement of dielectric constants is observed\nwith increasing Ts. The collective contribution of n-type and p-type carriers\nyields a clear peak in notable unusual dielectric behavior is successfully\nexplained by the Rezlescu model. The non-Debye type long range dielectric\nrelaxation phenomena is explained by electric modulus formalism. Fast response\nof the grain boundaries of the sample sintered at lower Ts sample leading to\nsmall dielectric spin relaxation time, t (several nanoseconds) have been\ndetermined using electric modulus spectra for the samples sintered at different\nTs. Two clear semicircles in impedance Cole-Cole plot have also been\nsuccessfully explained by employing two parallel RC equivalent circuits in\nseries configuration taking into account no electrode contribution. Such a long\nrelaxation time in NZFO ceramics could suitably be used in nanoscale spintronic\ndevices."
    },
    {
        "anchor": "Introduction of Sr into Bi2Se3 thin films by molecular beam epitaxy: SrxBi2Se3 is a candidate topological superconductor but its superconductivity\nrequires the intercalation of Sr by into the van-der-Waals gaps of Bi2Se3. We\nreport the synthesis of SrxBi2Se3 thin films by molecular beam epitaxy, and we\ncharacterize their structural, vibrational and electrical properties. X-ray\ndiffraction and Raman spectroscopy show evidence of substitutional Sr alloying\ninto the structure, while transport measurements allow us to correlate the\nincreasing Sr content with an increased n-type doping, but do not reveal\nsuperconductivity down to 1.5K. Our results suggest that Sr predominantly\noccupies sites within a quintuple layer, simultaneously substituting for Bi and\nas an interstitial. Our results motivate future density functional studies to\nfurther investigate the energetics of Sr substitution into Bi2Se3.",
        "positive": "Hydrodynamic heat transport regime in bismuth: a theoretical viewpoint: Bismuth is one of the rare materials in which second sound has been\nexperimentally observed. Our exact calculations of thermal transport with the\nBoltzmann equation predict the occurrence of this Poiseuille phonon flow\nbetween $\\approx$ 1.5 K and $\\approx$ 3.5 K, in sample size of 3.86 mm and 9.06\nmm, in consistency with the experimental observations. Hydrodynamic heat flow\ncharacteristics are given for any temperature: heat wave propagation length,\ndrift velocity, Knudsen number. We discuss a Gedanken-experiment allowing to\nassess the presence of a hydrodynamic regime in any bulk material."
    },
    {
        "anchor": "Polaron Induced Deformations in Carbon Nanotubes: We compute for the first time full elastic deformations, as well as length,\nof self-trapped electronic states in carbon nanotubes of general radius and\nchirality, within the unifying framework of a recently introduced two field\nmodel for electromechanics of carbon nano-structures. We find that deformations\nare highly non monotonic in the chiral angle, whereas the length of the polaron\nis not. Applications include nano-mechanical devices as electrically or\noptically driven nano-actuators.",
        "positive": "Heat transfer in rapidly solidifying supercooled pure melt during final\n  transient: The heat transfer model for a one-dimensional supercooled melt during the\nfinal stage of solidification is considered. The Stefan problem for the\ndetermination of the temperature distribution is solved under the condition\nthat (i) the interface approaches the specimen surface with a constant velocity\n$V$; (ii) the latent heat of solidification linearly depends on the interface\ntemperature; (iii) all the physical quantities given at the phase boundary are\npresented by linear combinations of the exponential functions of the interface\nposition. First we find the solution of the corresponding hyperbolic Stefan\nproblem within the framework of which the heat transfer is described by the\ntelegraph equation. The solution of the initial parabolic Stefan problem is\nthen found as a result of the limiting transition $V/V_H \\rightarrow 0$ $(V_H\n\\rightarrow \\infty)$, where $ V_H $ is the velocity of the propagation of the\nheat disturbances, in which the hyperbolic heat model teds to the parabolic\none."
    },
    {
        "anchor": "First-principles calculation of the lattice thermal conductivities of\n  \u03b1-, \u03b2-, and \u03b3-Si$_3$N$_4$: Lattice thermal conductivities (LTCs) of \\alpha-, \\beta-, and\n\\gamma-Si$_3$N$_4$ single crystals are investigated from ab initio anharmonic\nlattice dynamics, within the single-mode relaxation-time approximation of the\nlinearized phonon Boltzmann transport equation. At a temperature of 300 K, a\n\\kappa$_{xx}$ of 70 and a \\kappa$_{zz}$ of 98 (in units of Wm$^{-1}$K$^{-1}$)\nare obtained for \\alpha-Si$_3$N$_4$. For \\beta-Si$_3$N$_4$, \\kappa$_{xx}$ and\n\\kappa$_{zz}$ are found to be 71 and 194, respectively, which are consistent\nwith the reported experimental values of 69 and 180 for individual\n\\beta-Si$_3$N$_4$ grains in a ceramic. The theoretical \\kappa$_{xx}$ values of\n\\alpha- and \\beta-Si$_3$N$_4$ are comparable, while the \\kappa$_{zz}$ value of\n\\beta-Si$_3$N$_4$ is almost twice that of \\alpha-Si$_3$N$_4$, which\ndemonstrates the very large anisotropy in the LTC of the \\beta phase. It is\nfound that the large anisotropy in the LTC of \\beta-Si$_3$N$_4$ was caused by\nthe elongated Brillouin zone along the c* axis, where the acoustic phonons\nmostly contribute to LTC and have large group velocities even near the\nBrillouin zone boundary. The LTC of \\gamma-Si$_3$N$_4$ is 81, which is as small\nas that of \\alpha-Si$_3$N$_4$, although \\gamma-Si$_3$N$_4$ has much larger\nelastic constants. This means that elastic constants are not always a good\nindicator of LTC. We show that knowing the detailed distributions of both the\ngroup velocities and phonon lifetimes in the Brillouin zones is important for\ncharacterizing the LTC of the three phases.",
        "positive": "Meyer-Neldel and anti-Meyer-Neldel rule in microcrystalline silicon and\n  silicon carbide examined with Hall measurements: We study the electronic transport in lightly phosphorus-doped hydrogenated\nmicrocrystalline silicon ($\\mu$c-Si:H) and nominally undoped hydrogenated\nsilicon carbide ($\\mu$c-SiC:H) by temperature-dependent Hall measurements. The\nmaterial properties cover different crystallinities and doping concentrations.\nFor$\\mu$c-Si:H samples, the carrier concentration is altered by electron\nbombardment and subsequent step-wise annealing of defects. We describe the\nbehavior of conductivity, mobility, and carrier concentration in terms of the\nMeyer-Neldel rule (MNR) and anti-MNR. We present the first sample switching\nbetween them. A theoretical examination leverages the anti-MNR to describe\nelectronic room temperature properties, and it expands the statistical shift\nmodel."
    },
    {
        "anchor": "On microcontinuum field theories: the Eshelby stress tensor and\n  incompatibility conditions: We investigate linear theories of incompatible micromorphic elasticity,\nincompatible microstretch elasticity, incompatible micropolar elasticity and\nthe incompatible dilatation theory of elasticity (elasticity with voids). The\nincompatibility conditions and Bianchi identities are derived and discussed.\nThe Eshelby stress tensor (static energy momentum) is calculated for such\ninhomogeneous media with microstructure. Its divergence gives the driving\nforces for dislocations, disclinations, point defects and inhomogeneities which\nare called configurational forces.",
        "positive": "A hybrid approach to Fermi operator expansion: In a recent paper we have suggested that the finite temperature density\nmatrix can be computed efficiently by a combination of polynomial expansion and\niterative inversion techniques. We present here significant improvements over\nthis scheme. The original complex-valued formalism is turned into a purely real\none. In addition, we use Chebyshev polynomials expansion and fast summation\ntechniques. This drastically reduces the scaling of the algorithm with the\nwidth of the Hamiltonian spectrum, which is now of the order of the cubic root\nof such parameter. This makes our method very competitive for applications to\nab-initio simulations, when high energy resolution is required."
    },
    {
        "anchor": "Electronic structure and chemical bonding in Ti4SiC3 investigated by\n  soft x-ray emission spectroscopy and first principle theory: The electronic structure in the new transition metal carbide Ti4SiC3 has been\ninvestigated by bulk-sensitive soft x-ray emission spectroscopy and compared to\nthe well-studied Ti3SiC2 and TiC systems. The measured high-resolution Ti L, C\nK and Si L x-ray emission spectra are discussed with ab initio calculations\nbased on density-functional theory including core-to-valence dipole matrix\nelements. The detailed investigations of the Ti-C and Ti-Si chemical bonds\nprovide increased understanding of the physical properties of these\nnanolaminates. A strongly modified spectral shape is detected for the buried Si\nmonolayers due to Si 3p hybridization with the Ti 3d orbitals. As a result of\nrelaxation of the crystal structure and the charge-transfer from Ti (and Si) to\nC, the strength of the Ti-C covalent bond is increased. The differences between\nthe electronic and crystal structures of Ti4SiC3 and Ti3SiC2 are discussed in\nrelation to the number of Si layers per Ti layer in the two systems and the\ncorresponding change of materials properties.",
        "positive": "Trajectory sampling and finite-size effects in first-principles stopping\n  power calculations: Real-time time-dependent density functional theory (TDDFT) is presently the\nmost accurate available method for computing electronic stopping powers from\nfirst principles. However, obtaining application-relevant results often\ninvolves either costly averages over multiple calculations or ad hoc selection\nof a representative ion trajectory. We consider a broadly applicable,\nquantitative metric for evaluating and optimizing trajectories in this context.\nThis methodology enables rigorous analysis of the failure modes of various\ncommon trajectory choices in crystalline materials. Although randomly selecting\ntrajectories is common practice in stopping power calculations in solids, we\nshow that nearly 30% of random trajectories in an FCC aluminium crystal will\nnot representatively sample the material over the time and length scales\nfeasibly simulated with TDDFT, and unrepresentative choices incur errors of up\nto 60%. We also show that finite-size effects depend on ion trajectory via\n\"ouroboros\" effects beyond the prevailing plasmon-based interpretation, and we\npropose a cost-reducing scheme to obtain converged results even when expensive\ncore-electron contributions preclude large supercells. This work helps to\nmitigate poorly controlled approximations in first-principles stopping power\ncalculations, allowing 1-2 order of magnitude cost reductions for obtaining\nrepresentatively averaged and converged results."
    },
    {
        "anchor": "Solution processed large area field effect transistors from\n  dielectrophoreticly aligned arrays of carbon nanotubes: We demonstrate solution processable large area field effect transistors\n(FETs) from aligned arrays of carbon nanotubes (CNTs). Commercially available,\nsurfactant free CNTs suspended in aqueous solution were aligned between source\nand drain electrodes using ac dielectrophoresis technique. After removing the\nmetallic nanotubes using electrical breakdown, the devices displayed p-type\nbehavior with on-off ratios up to ~ 2X10^4. The measured field effect\nmobilities are as high as 123 cm2/Vs, which is three orders of magnitude higher\nthan typical solution processed organic FET devices.",
        "positive": "Gapped Nearly Free-Standing Graphene on an SiC(0001) Substrate Induced\n  by Manganese Atoms: The electron band structure of manganese-adsorbed graphene on an SiC(0001)\nsubstrate has been studied using angle-resolved photoemission spectroscopy.\nUpon introducing manganese atoms, the conduction band of graphene completely\ndisappears and the valence band maximum is observed at 0.4 eV below Fermi\nenergy. At the same time, the slope of the valence band decreases, approaching\nthe electron band structure calculated using the local density approximation\nmethod. While the former provides experimental evidence of the formation of\nnearly free-standing graphene on an SiC substrate, concomitant with a\nmetal-to-insulator transition, the latter suggests that its electronic\ncorrelations can be modified by foreign atoms. These results pave the way for\npromising device applications using graphene that is semiconducting and charge\nneutral."
    },
    {
        "anchor": "Homoepitaxy of rhombohedral-stacked MoS2 with room temperature\n  switchable ferroelectricity: The discovery of interfacial ferroelectricity in two-dimensional rhombohedral\n(3R)-stacked semiconductors opens up a new pathway for achieving ultrathin\ncomputing-in-memory devices. However, exploring ferroelectricity switching in\nnatural 3R crystals is difficult due to lack of co-existing 3R stacking\ndomains. Here, we present that MoS2 homoepitaxial patterns with 3R polytypic\ndomains can manifest switchable ferroelectricity at room-temperature. Based on\nthe diffusion limited aggregation theory, such MoS2 patterns are formed under\nthe low Mo chemical potential and low temperature with respect to common\nchemical vapor deposition synthesis. The alternation of 3R polytypes in the\nMoS2 homoepitaxial patterns, observed by scanning transmission electron\nmicroscopy, accounts for ferroelectricity switching. The MoS2 field-effect\ntransistors with 3R polytypic domains exhibit a repeatable counterclockwise\nhysteresis with gate voltage sweeping, an indication of ferroelectricity\nswitching, and the memory window exceeds those measured for compact-shaped 3R\nbilayer devices. This work provides a direct growth concept for layered\n3R-based ferroelectric memory.",
        "positive": "Langevin Simulation of Thermally Activated Magnetization Reversal in\n  Nanoscale Pillars: Numerical solutions of the Landau-Lifshitz-Gilbert micromagnetic model\nincorporating thermal fluctuations and dipole-dipole interactions (calculated\nby the Fast Multipole Method) are presented for systems composed of nanoscale\niron pillars of dimension 9 nm x 9 nm x 150 nm. Hysteresis loops generated\nunder sinusoidally varying fields are obtained, while the coercive field is\nestimated to be 1979 $\\pm$ 14 Oe using linear field sweeps at T=0 K. Thermal\neffects are essential to the relaxation of magnetization trapped in a\nmetastable orientation, such as happens after a rapid reversal of an external\nmagnetic field less than the coercive value. The distribution of switching\ntimes is compared to a simple analytic theory that describes reversal with\nnucleation at the ends of the nanomagnets. Results are also presented for\narrays of nanomagnets oriented perpendicular to a flat substrate. Even at a\nseparation of 300 nm, where the field from neighboring pillars is only $\\sim$ 1\nOe, the interactions have a significant effect on the switching of the magnets."
    },
    {
        "anchor": "Effects of Annealing Conditions on the Microstructure and Magnetic\n  Properties of the Perovskite Manganite, La0.75Sr0.25MnO3: The effects of annealing conditions upon the microstructure and the magnetic\nproperties of the colossal magnetoresistive manganite La0.75Sr0.25MnO3 have\nbeen investigated. Increasing the annealing temperature and time of annealing\nis seen to increase the size of crystallites within the samples. The\nspontaneous magnetic moment per formula unit and the Curie temperature, as\nobtained from Arrott plot analysis, are observed to depend upon the average\nsize of crystallites.",
        "positive": "Collective states of interacting ferromagnetic nanoparticles: Discontinuous magnetic multilayers [CoFe/Al2O3] are studied by use of\nmagnetometry, susceptometry and numeric simulations. Soft ferromagnetic\nCo80Fe20 nanoparticles are embedded in a diamagnetic insulating a-Al2O3 matrix\nand can be considered as homogeneously magnetized superspins exhibiting\nrandomness of size (viz. moment), position and anisotropy. Lacking\nintra-particle core-surface ordering, generic freezing processes into\ncollective states rather than individual particle blocking are encountered.\nWith increasing particle density one observes first superspin glass and then\nsuperferromagnetic domain state behavior. The phase diagram resembles that of a\ndilute disordered ferromagnet. Criteria for the identification of the\nindividual phases are given."
    },
    {
        "anchor": "Modelling a DR shaft operated with pure hydrogen using a\n  physical-chemical and CFD approach: The hydrogen-based route could be a valuable way to produce steel considering\nits low carbon dioxide emissions. In ULCOS, it is regarded as a long-term\noption, largely dependent on the emergence of a hydrogen economy. To anticipate\nits possible development, it was decided to check the feasibility of using 100%\nH2 in a Direct Reduction shaft furnace and to determine the best operating\nconditions, through appropriate experimental and modelling work. We developed\nfrom scratch a new model, called REDUCTOR, for simulating this process and\npredicting its performance. This sophisticated numerical model is based on the\nmathematical description of the detailed physical, chemical and thermal\nphenomena occurring. In particular, kinetics were derived from experi-ments.\nThe current version is suited to the reduction with pure hydrogen, but an\nextension of the model to CO is planned so that it will also be adapted to the\nsimulation and optimisation of the current DR processes. First re-sults have\nconfirmed that the reduction with hydrogen is much faster than that with CO,\nmaking it possible to design a hydrogen-operated shaft reactor quite smaller\nthan current MIDREX and HYL.",
        "positive": "High temperature deformation mechanisms in monolithic 3YTZP and 3YTZP\n  containing single wall carbon nanotubes: Monolithic 3YTZP and 3YTZP containing 2.5 vol.% of single-walled carbon\nnanotubes (SWCNT) were fabricated by Spark Plasma Sintering (SPS) at 1250 C.\nMicrostructural characterization of the as-fabricated 3YTZP/SWCNTs composite\nshows a homogeneous CNTs dispersion throughout of ceramic matrix. The specimens\nhave been crept at temperatures between 1100 and 1200 C in order to investigate\nthe influence of the SWCNTs addition on high temperature deformation mechanisms\nin zirconia. Slightly higher stress exponent values are found for 3YTZP/SWCNTs\nnanocomposites (n~2.5) compared to monolithic 3YTZP (n~2.0). However, the\nactivation energy in 3YTZP (Q = 715 +- 60 kJ/mol) experiences a reduction of\nabout 25% by the addition of 2.5 vol.% of SWCNTs (Q = 540 +- 40 kJ/mol).\nScanning electron microscopy studies indicate that there is no microstructural\nevolution in crept specimens, and Raman spectroscopy measurements show that\nSWCNTs preserved their integrity during the creep tests. All these results seem\nto indicate that the high temperature deformation mechanism is grain boundary\nsliding (GBS) accommodated by grain-boundary diffusion, which is influenced by\nyttrium segregation and the presence of SWCNTs at the grain boundary."
    },
    {
        "anchor": "Machine-learning structural reconstructions for accelerated point defect\n  calculations: Defects dictate the properties of many functional materials. To understand\nthe behaviour of defects and their impact on physical properties, it is\nnecessary to identify the most stable defect geometries. However, global\nstructure searching is computationally challenging for high-throughput defect\nstudies or materials with complex defect landscapes, like alloys or disordered\nsolids. Here, we tackle this limitation by harnessing a machine-learning\nsurrogate model to qualitatively explore the defect structural landscape. By\nlearning defect motifs in a family of related metal chalcogenide and mixed\nanion crystals, the model successfully predicts favourable reconstructions for\nunseen defects in unseen compositions for 90% of cases, thereby reducing the\nnumber of first-principles calculations by 73%. Using CdSe$_x$Te$_{1-x}$ alloys\nas an exemplar, we train a model on the end member compositions and apply it to\nfind the stable geometries of all inequivalent vacancies for a range of mixing\nconcentrations, thus enabling more accurate and faster defect studies for\nconfigurational complex systems.",
        "positive": "Thermal electric effects and heat generation in polypyrrole coated PET\n  fabrics: Polypyrrole chemically synthesized on PET gives rise to textiles with a high\nelectric conductivity, suitable for several applications from antistatics to\nelectromagnetic interference shielding devices. Here, we discuss investigations\non thermal electric performances of the polypyrrole coated PET in a wide range\nof temperatures above room temperature. The Seebeck coefficient turns out to be\ncomparable with that of metal thermocouple materials. Since polypyrrole shows\nextremely low thermal diffusivities regardless of the electrical conductivity,\nthe low thermal conductivity gives significant advantage to the thermoelectric\nfigure-of-merit ZT, comparable with that of some traditional inorganic\nthermoelectric materials. The heat generation is also investigated for possible\nheating textile devices."
    },
    {
        "anchor": "Tuning Photoinduced Terahertz Conductivity in Monolayer Graphene:\n  Optical Pump Terahertz Probe Spectroscopy: Optical pump-terahertz probe differential transmission measurements of\nas-prepared single layer graphene (AG)(unintentionally hole doped with Fermi\nenergy $E_F$ at $\\sim$180 meV), nitrogen doping compensated graphene (NDG) with\n$E_F$ $\\sim$10 meV and thermally annealed doped graphene (TAG) are examined\nquantitatively to understand the opposite signs of photo-induced dynamic\nterahertz conductivity $\\Delta\\sigma$. It is negative for AG and TAG but\npositive for NDG. We show that the recently proposed mechanism of multiple\ngenerations of secondary hot carriers due to Coulomb interaction of\nphotoexcited carriers with the existing carriers together with the intraband\nscattering can explain the change of photoinduced conductivity sign and its\nmagnitude. We give a quantitative estimate of $\\Delta\\sigma$ in terms of\ncontrolling parameters - the Fermi energy $E_F$ and momentum relaxation time\n$\\tau$. Further, the cooling of photoexcited carriers is analyzed using\nsuper-collision model which involves defect mediated collision of the hot\ncarriers with the acoustic phonons, thus giving an estimate of the deformation\npotential.",
        "positive": "Shakedown of unbound granular material: Compacted unbound granular materials are extensively used as sub-layer in\npavement design. Most pavement design guides assume that they are responsible\nfor the degradation and deformation of the roads and railways that they\nsupport. Biaxial tests are usually employed to investigate the elasto-plastic\nresponse of these materials to cyclic loading. A particularly interesting\nquestion is whether a limit load exists, below which the excitations shake\ndown, in the sense that the material does not accumulate further deformations.\nWe have carried out a detailed study of the elasto-plastic behavior of a simple\nmodel of unbound granular matter submitted to cyclic loading. The dissipated\nenergy through out the simulation has been used for the characterization of the\ndifferent regimes of responses."
    },
    {
        "anchor": "Fracture initiation in multi-phase materials: a systematic\n  three-dimensional approach using a FFT-based solver: This paper studies a two-phase material with a microstructure composed of a\nhard brittle reinforcement phase embedded in a soft ductile matrix. It\naddresses the full three-dimensional nature of the microstructure and\nmacroscopic deformation. A large ensemble of periodic microstructures is used,\nwhereby the individual grains of the two phases are modeled using equi-sized\ncubes. A particular solution strategy relying on the Fast Fourier Transform is\nadopted, which has a high computational efficiency both in terms of speed and\nmemory footprint, thus enabling a statistically meaningful analysis. This\nsolution method naturally accompanies the regular microstructural model, as the\nFast Fourier Transform relies on a regular grid.\n  Using the many considered microstructures as an ensemble, the average\narrangement of phases around fracture initiation sites is objectively\nidentified by the correlation between microstructure and fracture initiation --\nin three dimensions. The results show that fracture initiates where regions of\nthe hard phase are interrupted by bands of the soft phase that are aligned with\nthe direction of maximum shear. In such regions, the hard phase is arranged\nsuch that the area of the phase boundary perpendicular to the principal strain\ndirection is maximum, leading to high hydrostatic tensile stresses, while not\ninterrupting the shear bands that form in the soft phase. The local\nincompatibility that is present around the shear bands is responsible for a\nhigh plastic strain. By comparing the response to a two-dimensional\nmicrostructure it is observed that the response is qualitatively similar (both\nmacroscopically and microscopically). One important difference is that the\nlocal strain partitioning between the two phases is over-predicted by the\ntwo-dimensional microstructure, leading to an overestimation of damage.",
        "positive": "Electronic structure of molecular beam epitaxy grown\n  1T$^\\prime$-MoTe$_2$ film and strain effect: Atomically thin transition metal dichalcogenide films with distorted trigonal\n(1T$^\\prime$) phase have been predicted to be candidates for realizing quantum\nspin Hall effect. Growth of 1T$^\\prime$ film and experimental investigation of\nits electronic structure are critical. Here we report the electronic structure\nof 1T$^\\prime$-MoTe$_2$ films grown by molecular beam epitaxy (MBE). Growth of\nthe 1T$^\\prime$-MoTe$_2$ film depends critically on the substrate temperature,\nand successful growth of the film is indicated by streaky stripes in the\nreflection high energy electron diffraction and sharp diffraction spots in low\nenergy electron diffraction. Angle-resolved photoemission spectroscopy\nmeasurements reveal a metallic behavior in the as-grown film with an overlap\nbetween the conduction and valence bands. First principles calculation suggests\nthat a suitable tensile strain along the a-axis direction is needed to induce a\ngap to make it an insulator. Our work not only reports the electronic structure\nof MBE grown 1T$^\\prime$-MoTe$_2$ films, but also provides insights for strain\nengineering to make it possible for quantum spin Hall effect."
    },
    {
        "anchor": "Machine learning guided discovery of superconducting calcium\n  borocarbides: Pursuit of superconductivity in light-element systems at ambient pressure is\nof great experimental and theoretical interest. In this work, we combine a\nmachine learning (ML) method with first-principles calculations to efficiently\nsearch for the energetically favorable ternary Ca-B-C compounds. Three new\nlayered borocarbides (stable CaBC5 and metastable Ca2BC11 and CaB3C3) are\npredicted to be phonon-mediated superconductors at ambient pressure. The\nhexagonal CaB3C3 possesses the highest Tc of 26.05 K among the three compounds.\nThe {\\sigma}-bonging bands around the Fermi level account for the large\nelectron-phonon coupling ({\\lambda} = 0.980) of hexagonal CaB3C3. The ML-guided\napproach opens up a way for greatly accelerating the discovery of new high-Tc\nsuperconductors.",
        "positive": "Properties of CdTe layers deposited by a novel method -Pulsed Plasma\n  Deposition: CdTe and CdS are emerging as the most promising materials for thin film\nphotovoltaics in the quest of the achievement of grid parity. The major\nchallenge for the advancement of grid parity is the achievement of high quality\nat the same time as low fabrication cost. The present paper reports the results\nof the new deposition technique, Pulsed Plasma Deposition (PPD), for the growth\nof the CdTe layers on CdS/ZnO/quartz and quartz substrates. The PPD method\nallows to deposit at low temperature. The optical band gap of deposited layers\nis 1.50 eV, in perfect accord with the value reported in the literature for the\ncrystalline cubic phase of the CdTe. The films are highly crystalline with a\npredominant cubic phase, a random orientation of the grains of the film and\nhave an extremely low surface roughness of 4.6\\pm0.7 nm r.m.s.. The low\nroughness, compared to traditional thermal deposition methods (close space\nsublimation and vapour transport) permits the reduction of the active absorber\nand n-type semiconductor layers resulting in a dramatic reduction of material\nusage and the relative deposition issues like safety, deposition rate and\nultimately cost"
    },
    {
        "anchor": "Diffuse neutron scattering in relaxor ferroelectric PbMg1/3Nb2/3O3: High energy resolution neutron spin-echo spectroscopy has been used to\nmeasure intrinsic width of diffuse scattering discovered earlier in relaxor\nferroelectric crystals. The anisotropic and transverse components of the\nscattering have been observed in different Brillouin zones. Both components are\nfound to be elastic within experimental accuracy of 1 &#61549;eV. Possible\nphysical origin of the static-like behavior is discussed for each diffuse\nscattering contribution.",
        "positive": "A strong polarizing field in thin-film paraelectrics: The surface charge associated with the spontaneous polarization in\nferroelectrics is well known to cause a depolarizing field that can be\nparticularly detrimental in the thin-film geometry desirable for\nmicroelectronic devices. Incomplete screening of the surface charge, for\nexample by metallic electrodes or surface adsorbates, can lead to the formation\nof domains, suppression or reorientation of the polarization, or even\nstabilization of a higher energy non-polar phase . A huge amount of research\nand development effort has been invested in understanding the depolarizing\nbehavior and minimizing its unfavorable effects. Here we demonstrate the\nopposite behavior: A strong polarizing field that drives thin films of\nmaterials that are centrosymmetric and paraelectric in their bulk form into a\nnon-centrosymmetric, polar state. We illustrate the behavior using density\nfunctional computations for perovskite-structure potassium tantalate, KTaO$_3$,\nwhich is of considerable interest for its high dielectric constant, proximity\nto a quantum critical point and superconductivity. We then provide a simple\nrecipe to identify whether a particular material and film orientation will\nexhibit the effect, and develop an electrostatic model to estimate the critical\nthickness of the induced polarization in terms of well-known material\nparameters. Our results provide practical guidelines for exploiting the\nelectrostatic properties of thin-film ionic insulators to engineer novel\nfunctionalities for nanoscale devices."
    },
    {
        "anchor": "Abnormal behavior of preferred formation of cationic vacancy from the\n  interior in \u03b3-GeSe monolayer with the stereo-chemical antibonding\n  lone-pair state: Two-dimensional (2D) materials tend to have the preferably formation of\nvacancies at the outer surface. Here, contrary to the normal notion, we reveal\na type of vacancy that thermodynamically initiates from the interior part of\nthe 2D backbone of germanium selenide ({\\gamma}-GeSe). Interestingly, the\nGe-vacancy (VGe) in the interior part of {\\gamma}-GeSe possesses the lowest\nformation energy amongst the various types of defects considered. We also find\na low diffusion barrier (1.04 eV) of VGe which is a half of those of sulfur\nvacancy in MoS2. The facile formation of mobile VGe is rooted in the\nantibonding coupling of the lone-pair Ge 4s and Se 4p states near the valence\nband maximum, which also exists in other gamma-phase MX (M=Sn, Ge; X=S, Te).\nThe VGe is accompanied by a shallow acceptor level in the band gap and induces\nstrong infrared light absorption and p-type conductivity. The VGe located in\nthe middle cationic Ge sublattice is well protected by the surface Se layers-a\nfeature that is absent in other atomically thin materials. Our work suggests\nthat the unique well-buried inner VGe, with the potential of forming\nstructurally protected ultrathin conducting filaments, may render the GeSe\nlayer an ideal platform for quantum emitting, memristive, and neuromorphic\napplications.",
        "positive": "A New Mechanism for the Alpha to Omega Martensitic Transformation in\n  Pure Titanium: We propose a new direct mechanism for the pressure driven alpha to omega\nmartensitic transformation in pure titanium. A systematic algorithm enumerates\nall possible mechanisms whose energy barriers are evaluated. A new, homogeneous\nmechanism emerges with a barrier at least four times lower than other\nmechanisms. This mechanism remains favorable in a simple nucleation model."
    },
    {
        "anchor": "From flexoelectricity to absolute deformation potentials: The case of\n  SrTiO$_3$: Based on recent developments in the first-principles theory of\nflexoelectricity, we generalize the concept of absolute deformation potential\nto arbitrary nonpiezoelectric insulators and deformation fields. To demonstrate\nour formalism, we calculate the response of the band edges of SrTiO$_3$ to both\ndynamic (sound waves) and static (bending) mechanical loads, respectively at\nthe bulk level and in a slab geometry. Our results have important implications\nfor the understanding of strain-gradient-related phenomena in crystalline\ninsulators, formally unifying the description of band-structure and\nelectrostatic effects.",
        "positive": "Chlorine adsorption on the Cu(111) surface: We investigate the adsorption of chlorine on the Cu(111) surface with full\npotential all-electron density functional calculations. Chlorine adsorption at\nthe fcc hollow sites is slightly preferred over that at the hcp hollow. The\nadsorption geometry is in excellent agreement with electron diffraction and ion\nscattering data. Adsorption energies and surface diffusion barriers are close\nto those deduced from experiment."
    },
    {
        "anchor": "Switching ferromagnetic spins by an ultrafast laser pulse: Emergence of\n  giant optical spin-orbit torque: Faster magnetic recording technology is indispensable to massive data storage\nand big data sciences. {All-optical spin switching offers a possible solution},\nbut at present it is limited to a handful of expensive and complex rare-earth\nferrimagnets. The spin switching in more abundant ferromagnets may\nsignificantly expand the scope of all-optical spin switching. Here by studying\n40,000 ferromagnetic spins, we show that it is the optical spin-orbit torque\nthat determines the course of spin switching in both ferromagnets and\nferrimagnets. Spin switching occurs only if the effective spin angular momentum\nof each constituent in an alloy exceeds a critical value. Because of the strong\nexchange coupling, the spin switches much faster in ferromagnets than\nweakly-coupled ferrimagnets. This establishes a paradigm for all-optical spin\nswitching. The resultant magnetic field (65 T) is so big that it will\nsignificantly reduce high current in spintronics, thus representing the\nbeginning of photospintronics.",
        "positive": "Tantalum Monoarsenide: an Exotic Compensated Semimetal: Compared with the semiconductors such as silicon and gallium arsenide which\nhave been used widely for decades, semimetals have not received much attention\nin the field of condensed matter physics until very recently. The realization\nof electronic topological properties has motivated interest of investigations\non Dirac semimetals and Weyl semimetals, which are predicted to show\nunprecedented features beyond the classical electronic theories of metals. In\nthis letter for the first time we report the electric transport properties of a\nrobust Weyl semimetal candidate proposed by recent theoretical calculations,\nTaAs. Our study shows that this bulk material manifests ultrahigh carrier\nmobility ($\\mathrm{5\\times10^5 cm^2/V\\cdot{s}}$) accompanied by an extremely\nlarge, unsaturated linear magnetoresistance ($\\mathrm{MR}$), which reaches 5400\nat 10 Kelvins in a magnetic field of 9 Teslas and 2.47$\\times$10$^4$ at 1.5\nKelvins in a magnetic field of 56 Teslas. We also observed strong Shubnikov-de\nHaas (SdH) oscillations associated with an extremely low quantum limit ($\\sim$8\nTeslas). Further studies on TaAs, especially in the ultraquantum limit regime,\nwill help to extend the realization of the topological properties of these\nexotic electrons."
    },
    {
        "anchor": "A Comparative Study of Machine Learning Models Predicting Energetics of\n  Interacting Defects: Interacting defect systems are ubiquitous in materials under realistic\nscenarios, yet gaining an atomic-level understanding of these systems from a\ncomputational perspective is challenging - it often demands substantial\nresources due to the necessity of employing supercell calculations. While\nmachine learning techniques have shown potential in accelerating materials\nsimulations, their application to systems involving interacting defects remains\nrelatively rare. In this work, we present a comparative study of three\ndifferent methods to predict the free energy change of systems with interacting\ndefects. We leveraging a limited dataset from Density Functional Theory(DFT)\ncalculations to assess the performance models using materials descriptors,\ngraph neural networks and cluster expansion. Our findings indicate that the\ncluster expansion model can achieve precise energetics predictions even with\nthis limited dataset. Furthermore, with synthetic data generate from cluster\nexpansion model at near-DFT levels, we obtained enlarged dataset to assess the\ndemands on data for training accurate prediction models using graph neural\nnetworks for systems featuring interacting defects. A brief discussion of the\ncomputational cost for each method is provided at the end. This research\nprovide a preliminary evaluation of applying machine learning techniques in\nimperfect surface systems.",
        "positive": "In situ diffraction study of catalytic hydrogenation of VO2: Stable\n  phases and origins of metallicity: Controlling electronic population through chemical doping is one way to tip\nthe balance between competing phases in materials with strong electronic\ncorrelations. Vanadium dioxide exhibits a first-order phase transition at\naround 338 K between a high temperature, tetragonal, metallic state (T) and a\nlow temperature, monoclinic, insulating state (M1), driven by electron-electron\nand electron-lattice interactions. Intercalation of VO2 with atomic hydrogen\nhas been demonstrated, with evidence that this doping suppresses the\ntransition. However, the detailed effects of intercalated H on the crystal and\nelectronic structure of the resulting hydride have not been previously\nreported. Here we present synchrotron and neutron diffraction studies of this\nmaterial system, mapping out the structural phase diagram as a function of\ntemperature and hydrogen content. In addition to the original T and M1 phases,\nwe find two orthorhombic phases, O1 and O2, which are stabilized at higher\nhydrogen content. We present density functional calculations that confirm the\nmetallicity of these states and discuss the physical basis by which hydrogen\nstabilizes conducting phases, in the context of the metal-insulator transition."
    },
    {
        "anchor": "Noncontact friction: Role of phonon damping and its nonuniversality: While obtaining theoretical predictions for dissipation during sliding motion\nis a difficult task, one regime that allows for analytical results is the\nso-called noncontact regime, where a probe is weakly interacting with the\nsurface over which it moves. Studying this regime for a model crystal, we\nextend previously obtained analytical results and confirm them quantitatively\nvia particle based computer simulations. Accessing the subtle regime of weak\ncoupling in simulations is possible via use of Green-Kubo relations. The\nanalysis allows to extract and compare the two paradigmatic mechanisms that\nhave been found to lead to dissipation: phonon radiation, prevailing even in a\npurely elastic solid, and phonon damping, e.g., caused by viscous motion of\ncrystal atoms. While phonon radiation is dominant at large probe-surface\ndistances, phonon damping dominates at small distances. Phonon radiation is\nfurthermore a pairwise additive phenomenon so that the dissipation due to\ninteraction with different parts (areas) of the surface adds up. This additive\nscaling results from a general one-to-one mapping between the mean\nprobe-surface force and the friction due to phonon radiation, irrespective of\nthe nature of the underlying pair interaction. In contrast, phonon damping is\nstrongly nonadditive, and no such general relation exists. We show that for\ncertain cases, the dissipation can even {\\it decrease} with increasing surface\narea the probe interacts with. The above properties, which are rooted in the\nspatial correlations of surface fluctuations, are expected to have important\nconsequences when interpreting experimental measurements, as well as scaling\nwith system size.",
        "positive": "Body-centered phase of shock loaded Cu: Single crystal Cu when shock loaded in certain direction for a certain narrow\nrange of piston velocities undergoes a structural phase transition from\nface-centered cubic to different body-centered phases. Based on molecular\ndynamic simulations, the manuscript identifies new phases of Cu through\ndetailed radial distribution function and x-ray diffraction analysis.\nIdentification of the new phases of Cu should initiate a re-evaluation of phase\ndiagram for Cu under high temperature and pressure conditions."
    },
    {
        "anchor": "Roughness-induced domain structure in perpendicular Co/Ni multilayers: We investigate the correlation between roughness, remanence and coercivity in\nCo/Ni films grown on Cu seed layers of varying thickness. Increasing the Cu\nseed layer thickness of Ta/Cu/8x[Co/Ni] thin films increases the roughness of\nthe films. In-plane magnetization loops show that both the remanance and\ncoercivity increase with increasing seed layer roughness. Polar Kerr microscopy\nand magnetic force microscopy reveal that the domain density also increases\nwith roughness. Finite element micromagnetic simulations performed on\nstructures with periodically modulated surfaces provide further insight. They\nconfirm the connection between domain density and roughness, and identify the\nmicrosocpic structure of the domain walls as the source of the increased\nremanence in rough films. The simulations predict that the character of the\ndomain walls changes from Bloch-like in smooth films to N\\'eel-like for rougher\nfilms.",
        "positive": "Data Mining for Three-Dimensional Organic Dirac Materials: Focus on\n  Space Group 19: We combined the group theory and data mining approach within the Organic\nMaterials Database that leads to the prediction of stable Dirac-point nodes\nwithin the electronic band structure of 3-dimensional organic crystals. We find\na particular space group $P2_12_12_1$ ($\\#19$) that is conducive to the Dirac\nnodes formation. We prove that nodes are a consequence of the orthorhombic\ncrystal structure. Within the electronic band structure, two different kinds of\nnodes can be distinguished: 8-fold degenerate Dirac nodes protected by the\ncrystalline symmetry and 4-fold degenerate Dirac nodes protected by band\ntopology. Mining the Organic Materials Database, we present band structure\ncalculations and symmetry analysis for 6 previously synthesized organic\nmaterials. In all these materials, the Dirac nodes are well separated within\nthe energy and located near the Fermi surface, which opens up a possibility for\ntheir direct experimental observation."
    },
    {
        "anchor": "Lattice deformation at the sub-micron scale: X-ray nanobeam measurements\n  of elastic strain in electron shuttling devices: The lattice strain induced by metallic electrodes can impair the\nfunctionality of advanced quantum devices operating with electron or hole\nspins. Here we investigate the deformation induced by CMOS-manufactured\ntitanium nitride electrodes on the lattice of a buried, 10 nm-thick Si/SiGe\nQuantum Well by means of nanobeam Scanning X-ray Diffraction Microscopy. We\nwere able to measure TiN electrode-induced local modulations of the strain\ntensor components in the range of $2 - 8 \\times 10^{-4}$ with ~60 nm lateral\nresolution. We have evaluated that these strain fluctuations are reflected into\nlocal modulations of the potential of the conduction band minimum larger than 2\nmeV, which is close to the orbital energy of an electrostatic quantum dot. We\nobserve that the sign of the strain modulations at a given depth of the quantum\nwell layer depends on the lateral dimensions of the electrodes. Since our work\nexplores the impact of device geometry on the strain-induced energy landscape,\nit enables further optimization of the design of scaled CMOS-processed quantum\ndevices.",
        "positive": "Observation of Type I/II Transition in GaAs/InGaP Heterostructure by C-V\n  Profiling: It is known in the literature that InGaP alloy synthesized within a certain\nrange of growth temperature (520 - 720 degree Centrigrade) shows Cu-Pt crystal\nordering. This ordering reduces the band gap energy . It was predicted that the\nordering induced modification of energy levels of InGaP lowers its conduction\nband edge, which could change a type I band alignment at a GaAs/InGaP\nheterojunction to type II . Here we report the first observation of this\nordering related type I/II transition for a GaAs/InGaP heterojunction by C-V\nprofiling experiments done at room temperature ."
    },
    {
        "anchor": "Magnetothermal cooling with a phase separated manganite: We show that temperature of a current (I = 20 mA) carrying manganite\n(Nd0.5Ca0.5Mn0.93Ni0.07O3) in presence of a magnetic field (H) decreases\nabruptly as much as deltaT = 45 K (7 K) accompanied by a step like decrease in\nmagnetoresistance at a critical value of H when the base temperature is 40 K\n(100 K). The magnitude of deltaT and the position of magnetoresistance step\ndecrease towards lower H with decreasing amplitude of the current. We discuss\npossible origins of the current and magnetic- field driven temperature change\nwhich may find applications in magnetothermal refrigeration besides\nmagnetocaloric effect.",
        "positive": "Transfer learning for materials informatics using crystal graph\n  convolutional neural network: For successful applications of machine learning in materials informatics, it\nis necessary to overcome the inaccuracy of predictions ascribed to insufficient\namount of data. In this study, we propose a transfer learning using a crystal\ngraph convolutional neural network (TL-CGCNN). Herein, TL-CGCNN is pretrained\nwith big data such as formation energies for crystal structures, and then used\nfor predicting target properties with relatively small data. We confirm that\nTL-CGCNN can improve predictions of various properties such as bulk moduli,\ndielectric constants, and quasiparticle band gaps, which are computationally\ndemanding, to construct big data for materials. Moreover, we quantitatively\nobserve that the prediction of properties in target models via TL-CGCNN becomes\nmore accurate with an increase in size of training dataset in pretrained\nmodels. Finally, we confirm that TL-CGCNN is superior to other regression\nmethods in the predictions of target properties, which suffer from small amount\nof data. Therefore, we conclude that TL-CGCNN is promising along with compiling\nbig data for materials that are easy to accumulate and relevant to the target\nproperties."
    },
    {
        "anchor": "Insight into Ideal Shear Strength of Ni-based Dilute Alloys using\n  First-Principles Calculations and Correlational Analysis: The present work examines the effect of alloying elements (denoted X) on the\nideal shear strength for 26 dilute Ni-based alloys, Ni$_{11}$X, as determined\nby first-principles calculations of pure alias shear deformations. The\nvariations in ideal shear strength are quantitatively explored with\ncorrelational analysis techniques, showing the importance of atomic properties\nsuch as size and electronegativity. The shear moduli of the alloys are affirmed\nto show a strong linear relationship with their ideal shear strengths, while\nthe shear moduli of the individual alloying elements were not indicative of\nalloy shear strength. Through combination with available ideal shear strength\ndata on Mg alloys, a potential application of the Ni alloy data is demonstrated\nin the search for a set of atomic features suitable for machine learning\napplications to mechanical properties. As another illustration, the predicted\nNi ideal shear strengths play a key role in a predictive multiscale framework\nfor deformation behavior of single crystal alloys at large strains, as shown by\nsimulated stress-strain curves.",
        "positive": "Molecular Dynamics Simulation of the Hydrogen Isotope Sputtering of\n  Graphite: We used a molecular dynamics simulation with the modified Brenner reactive\nempirical bond order potential to investigate the erosion of a graphite surface\ndue to the incidence of hydrogen, deuterium, and tritium atoms. Incident\nparticles cause pressure on the graphite surface, and the chemical bond between\ngraphene layers then generates heat to erode the graphite surface. We evaluated\nthe speed of surface destruction by calculating the pseudo-radial distribution\nfunction. The speed of surface destruction due to incident hydrogen isotopes\nwas higher than that due to hydrogen atoms. The surface destruction increased\nexponentially and its decay time constant was a power function of the incident\nenergy. We measured the erosion yield, which indicated a steady state for the\ngraphite erosion. The erosion yield flux in the steady state increased linearly\nwith the incident energy. The erosion yield flux was almost independent of the\ntype of incident particle, and the erosion yield start time was smaller for\nhydrogen isotopes than for hydrogen atoms."
    },
    {
        "anchor": "Graphene Photonics and Optoelectronics: The richness of optical and electronic properties of graphene attracts\nenormous interest. Graphene has high mobility and optical transparency, in\naddition to flexibility, robustness and environmental stability. So far, the\nmain focus has been on fundamental physics and electronic devices. However, we\nbelieve its true potential to be in photonics and optoelectronics, where the\ncombination of its unique optical and electronic properties can be fully\nexploited, even in the absence of a bandgap, and the linear dispersion of the\nDirac electrons enables ultra-wide-band tunability. The rise of graphene in\nphotonics and optoelectronics is shown by several recent results, ranging from\nsolar cells and light emitting devices, to touch screens, photodetectors and\nultrafast lasers. Here we review the state of the art in this emerging field.",
        "positive": "Nanoporous Copper-Nickel - Macroscopic bodies of a strong and deformable\n  nanoporous base metal by dealloying: Uniform macroscopic samples of nanoporous metal with high deformability have\nso far been limited to precious metals such as Au, Pd and Pt. Here we propose\nnanoporous Copper-Nickel (npCN) as a nanoporous base metal that can be made\nwith mm dimensions and exhibits significant deformability. NpCN forms a uniform\nbicontinous network structure with feature sizes that can be controlled from 13\nto 40 nm by thermal annealing. Continuous compression tests confirm ductile\ndeformation behavior accompanied with a high strength compared to macroporous\nCu- and Ni-foams with similar solid fraction."
    },
    {
        "anchor": "Resonance fluorescence from a coherently driven semiconductor quantum\n  dot in a cavity: We show that resonance fluorescence, i.e. the resonant emission of a\ncoherently driven two-level system, can be realized with a semiconductor\nquantum dot. The dot is embedded in a planar optical micro-cavity and excited\nin a wave-guide mode so as to discriminate its emission from residual laser\nscattering. The transition from the weak to the strong excitation regime is\ncharacterized by the emergence of oscillations in the first-order correlation\nfunction of the fluorescence, g(t), as measured by interferometry. The\nmeasurements correspond to a Mollow triplet with a Rabi splitting of up to 13.3\nmicro eV. Second-order-correlation measurements further confirm non-classical\nlight emission.",
        "positive": "Ultrafast Transient Dynamics of Adsorbates on Surfaces Deciphered: The\n  Case of CO on Cu(100): Time-resolved vibrational spectroscopy constitutes an invaluable experimental\ntool for monitoring hot-carrier induced surface reactions. However, the absence\nof a full understanding on the precise microscopic mechanisms causing the\ntransient spectral changes has been limiting its applicability. Here we\nintroduce a robust first-principles theoretical framework that successfully\nexplains both the nonthermal frequency and linewidth changes of the CO internal\nstretch mode on Cu(100) induced by femtosecond laser pulses. Two distinct\nprocesses engender the changes: electron-hole pair excitations underlie the\nnonthermal frequency shifts, while electron-mediated vibrational mode coupling\ngives rise to linewidth changes. Furthermore, the origin and precise sequence\nof coupling events are finally identified."
    },
    {
        "anchor": "Crystal Growth of a New 8H Perovskite Sr8Os6.3O24 Exhibiting High TC\n  Ferromagnetism: Single crystals of a new twinned hexagonal perovskite compound Sr8Os6.3O24\nhave been synthesized, and structural and magnetic properties have been\ndetermined. The compound crystallizes in a hexagonal cell with lattice\nparameters a = 9.6988(3) {\\AA} and c = 18.1657(5) {\\AA}. The structure is an\neight-layered hexagonal B-site deficient perovskite with the layer sequence\n(ccch)2 and represents the first example of a hexagonal structure among 5d\noxides adopting a twin option. The sample shows spontaneous ferromagnetic\nmagnetization below 430 K with a small saturation moment of 0.11 {\\mu}B/Os ion.\nThis is the highest Curie temperature (TC) reported for any bulk perovskite\ncontaining only 5d ions at the B site.",
        "positive": "Probing charge order of monolayer NbSe$_2$ within a bulk crystal: Atomically thin transition metal dichalcogenides can exhibit markedly\ndifferent electronic properties compared to their bulk counterparts. In the\ncase of NbSe$_2$, the question of whether its charge density wave (CDW) phase\nis enhanced in the monolayer limit has been the subject of intense debate,\nprimarily due to the difficulty of decoupling this order from its environment.\nHere, we address this challenge by using a misfit crystal that comprises\nNbSe$_2$ monolayers separated by SnSe rock-salt spacers, a structure that\nallows us to investigate a monolayer crystal embedded in a bulk matrix. We\nestablish an effective monolayer electronic behavior of the misfit crystal by\nstudying its transport properties and visualizing its electronic structure by\nangle-resolved photoemission measurements. We then investigate the emergence of\nthe CDW by tracking the temperature dependence of its collective modes. Our\nfindings reveal a nearly sixfold enhancement in the CDW transition temperature,\nproviding compelling evidence for the profound impact of dimensionality on\ncharge order formation in NbSe$_2$."
    },
    {
        "anchor": "Coherent Phonon Transport in Two-dimensional Graphene Superstructures: Coherent wave effects of thermal phonons hold promise of transformative\nopportunities in thermal transport control but remain largely unexplored due to\nthe small wavelength of thermal phonons, typically below a few nanometers. This\nsmall length scale indicates that, instead of artificial phononic crystals, a\nmore promising direction is to examine the coherent phonon effects in natural\nmaterials with hierarchical superstructures matching the thermal phonon\nwavelength. In this work, we use first-principles simulations to characterize\nthe previously unstudied thermal properties of D-graphene and T-graphene,\ntwo-dimensional carbon allotropes based upon the traditional graphene structure\nbut containing a secondary, in-plane periodicity. We find that despite very\nsimilar atomic structure and bonding strength, D-graphene and T-graphene\npossess significantly different thermal properties than that of pristine\ngraphene. At room temperature, the calculated thermal conductivity of\nD-graphene and T-graphene is 600 Wm-1K-1 and 800 Wm-1K-1 compared to over 3000\nWm-1K-1 for graphene. We attribute these distinct properties to the presence of\nnaturally occurring, low frequency optical phonon modes that display\ncharacteristics of phonon coherence and arise from a folding of the acoustic\nmodes and the associated frequency gap opening, a phenomenon also found in\nsuperlattices where an out of plane periodicity is introduced. Furthermore, we\nobserve significantly enhanced Umklapp scatterings in D- and T-graphene that\nlargely suppress the hydrodynamic phonon transport in pristine graphene. Our\nstudy presents D-graphene and T-graphene as ideal model systems to explore the\ncoherent phonon effects in 2D and demonstrates the potential of using coherent\nphonon effects to significantly modify thermal transport of 2D materials\nwithout making drastic changes to their fundamental compositions.",
        "positive": "Evidence for semiconducting behavior with a narrow band gap of Bernal\n  graphite: We have studied the resistivity of a large number of highly oriented graphite\nsamples with areas ranging from several mm$^2$ to a few $\\mu$m$^2$ and\nthickness from $\\sim 10 $nm to several tens of micrometers. The measured\nresistance can be explained by the parallel contribution of semiconducting\ngraphene layers with low carrier density $< 10^9$ cm$^{-2}$ and the one from\nmetallic-like internal interfaces. The results indicate that ideal graphite\nwith Bernal stacking structure is a narrow-gap semiconductor with an energy gap\n$E_g \\sim 40 $meV."
    },
    {
        "anchor": "Solution-Processable Graphene Oxide as an Efficient Hole Injection Layer\n  for High Luminance Organic Light-Emitting Diodes: The application of solution-processable graphene oxide (GO) as hole injection\nlayer in organic light-emitting diodes (OLEDs) is demonstrated. High luminance\nof over 53,000 cd m-2 is obtained at only 10 V. The results will unlock a route\nof applying GO in flexible OLEDs and other electrode applications.",
        "positive": "Spintronic Properties of Zigzag-Edged Triangular Graphene Flakes: We investigate quantum transport properties of triangular graphene flakes\nwith zigzag edges by using first principles calculations. Triangular graphene\nflakes have large magnetic moments which vary with the number of hydrogen atoms\nterminating its edge atoms and scale with its size. Electronic transmission and\ncurrent-voltage characteristics of these flakes, when contacted with metallic\nelectrodes, reveal spin valve and remarkable rectification features. The\ntransition from ferromagnetic to antiferromagnetic state under bias voltage\ncan, however, terminate the spin polarizing effects for specific flakes.\nGeometry and size dependent transport properties of graphene flakes may be\ncrucial for spintronic nanodevice applications."
    },
    {
        "anchor": "Absolute Determination of Optical Constants by a Direct Physical\n  Modeling of Reflection Electron Energy Loss Spectra: We present an absolute extraction method of optical constants of metal from\nthe measured reflection electron energy loss (REELS) spectra by using the\nrecently developed reverse Monte Carlo (RMC) technique. The method is based on\na direct physical modeling of electron elastic and electron inelastic\nscattering near the surface region where the surface excitation becomes\nimportant to fully describe the spectrum loss feature intensity in relative to\nthe elastic peak intensity. An optimization procedure of oscillator parameters\nappeared in the energy loss function (ELF) for describing electron inelastic\nscattering due to the bulk- and surface-excitations was performed with the\nsimulated annealing method by a successive comparison between the measured and\nMonte Carlo simulated REELS spectra. The ELF and corresponding optical\nconstants of Fe were obtained from the REELS spectra measured at incident\nenergies of 1000, 2000 and 3000 eV. The validity of the present optical data\nhas been verified with the f- and ps-sum rules showing the accuracy and\napplicability of the present approach. Our data are also compared with previous\noptical data from other sources.",
        "positive": "Growth of strontium ruthenate films by hybrid molecular beam epitaxy: We report on the growth of epitaxial Sr2RuO4 films using a hybrid molecular\nbeam epitaxy approach in which a volatile precursor containing RuO4 is used to\nsupply ruthenium and oxygen. The use of the precursor overcomes a number of\nissues encountered in traditional MBE that uses elemental metal sources.\nPhase-pure, epitaxial thin films of Sr2RuO4 are obtained. At high substrate\ntemperatures, growth proceeds in a layer-by-layer mode with intensity\noscillations observed in reflection high-energy electron diffraction. Films are\nof high structural quality, as documented by x-ray diffraction, atomic force\nmicroscopy, and transmission electron microscopy. The method should be suitable\nfor the growth of other complex oxides containing ruthenium, opening up\nopportunities to investigate thin films that host rich exotic ground states."
    },
    {
        "anchor": "A first-principles approach to nonlinear lattice dynamics: Anomalous\n  spectra in PbTe: Here we introduce a new approach to compute the finite temperature lattice\ndynamics from first-principles via the newly developed slave mode expansion. We\nstudy PbTe where inelastic neutron scattering (INS) reveals strong signatures\nof nonlinearity as evidenced by anomalous features which emerge in the phonon\nspectra at finite temperature. Using our slave mode expansion in the classical\nlimit, we compute the vibrational spectra and show remarkable agreement with\ntemperature dependent INS measurements. Furthermore, we resolve experimental\ncontroversy by showing that there are no appreciable local nor global\nspontaneously broken symmetries at finite temperature and that the anomalous\nspectral features simply arise from two anharmonic interactions. Our approach\nshould be broadly applicable across the periodic table.",
        "positive": "Multiband theory of multi-exciton complexes in self-assembled quantum\n  dots: We report on a multiband microscopic theory of many-exciton complexes in\nself-assembled quantum dots. The single particle states are obtained by three\nmethods: single-band effective-mass approximation, the multiband $k\\cdot p$\nmethod, and the tight-binding method. The electronic structure calculations are\ncoupled with strain calculations via Bir-Pikus Hamiltonian. The many-body wave\nfunctions of $N$ electrons and $N$ valence holes are expanded in the basis of\nSlater determinants. The Coulomb matrix elements are evaluated using statically\nscreened interaction for the three different sets of single particle states and\nthe correlated $N$-exciton states are obtained by the configuration interaction\nmethod. The theory is applied to the excitonic recombination spectrum in\nInAs/GaAs self-assembled quantum dots. The results of the single-band\neffective-mass approximation are successfully compared with those obtained by\nusing the of $k\\cdot p$ and tight-binding methods."
    },
    {
        "anchor": "Origins of singlet fission in solid pentacene from an ab initio\n  Green's-function approach: We develop a new first-principles approach to predict and understand rates of\nsinglet fission with an ab initio Green's-function formalism based on many-body\nperturbation theory. Starting with singlet and triplet excitons computed from a\nGW plus Bethe-Salpeter equation approach, we calculate the exciton--bi-exciton\ncoupling to lowest order in the Coulomb interaction, assuming a final state\nconsisting of two non-interacting spin-correlated triplets with finite\ncenter-of-mass momentum. For crystalline pentacene, symmetries dictate that the\nonly purely Coulombic fission decay from a bright singlet state requires a\nfinal state consisting of two inequivalent nearly degenerate triplets of\nnonzero, equal and opposite, center-of-mass momenta. For such a process, we\npredict a singlet lifetime of 40 to 150 fs, in very good agreement with\nexperimental data, indicating that this process can dominate singlet fission in\ncrystalline pentacene. Our approach is general and provides a framework for\npredicting and understanding multiexciton interactions in solids.",
        "positive": "Interface effects in spin-dependent tunneling: In the past few years the phenomenon of spin dependent tunneling (SDT) in\nmagnetic tunnel junctions (MTJs) has aroused enormous interest and has\ndeveloped into a vigorous field of research. The large tunneling\nmagnetoresistance (TMR) observed in MTJs garnered much attention due to\npossible application in random access memories and magnetic field sensors. This\nled to a number of fundamental questions regarding the phenomenon of SDT. One\nsuch question is the role of interfaces in MTJs and their effect on the spin\npolarization of the tunneling current and TMR. In this paper we consider\ndifferent models which suggest that the spin polarization is primarily\ndetermined by the electronic and atomic structure of the ferromagnet/insulator\ninterfaces rather than by their bulk properties. First, we consider a simple\ntight-binding model which demonstrates that the existence of interface states\nand their contribution to the tunneling current depend on the degree of\nhybridization between the orbitals on metal and insulator atoms. The decisive\nrole of the interfaces is further supported by studies of spin-dependent\ntunneling within realistic first-principles models of Co/vacuum/Al,\nCo/Al2O3/Co, Fe/MgO/Fe, and Co/SrTiO3/Co MTJs. We find that variations in the\natomic potentials and bonding strength near the interfaces have a profound\neffect resulting in the formation of interface resonant states, which\ndramatically affect the spin polarization and TMR. The strong sensitivity of\nthe tunneling spin polarization and TMR to the interface atomic and electronic\nstructure dramatically expands the possibilities for engineering optimal MTJ\nproperties for device applications."
    },
    {
        "anchor": "Simulations with machine learning potentials identify the ion conduction\n  mechanism mediating non-Arrhenius behavior in LGPS: Li$_{10}$Ge(PS$_6$)$_2$ (LGPS) is a highly concentrated solid electrolyte, in\nwhich Coulombic repulsion between neighboring cations is hypothesized as the\nunderlying reason for concerted ion hopping, a mechanism common among\nsuperionic conductors such as Li$_7$La$_3$Zr$_2$O$_{12}$ (LLZO) and\nLi$_{1.3}$Al$_{0.3}$Ti$_{1.7}$(PO$_4$)$_3$ (LATP). While first principles\nsimulations using molecular dynamics (MD) provide insight into the Li$^+$\ntransport mechanism, historically, there has been a gap in the temperature\nranges studied in simulations and experiments. Here, we used a neural network\n(NN) potential trained on density functional theory (DFT) simulations, to run\nup to 40-nanosecond long MD simulations at DFT-like accuracy to characterize\nthe ion conduction mechanisms across a range of temperatures that includes\nprevious simulations and experimental studies. We have confirmed a Li$^+$\nsublattice phase transition in LGPS around 400 K, below which the\n\\textit{ab}-plane diffusivity $D^*_{ab}$ is drastically reduced. Concomitant\nwith the sublattice phase transition near 400 K, there is less cation-cation\n(cross) correlation, as characterized by Haven ratios closer to 1, and the\nvibrations in the system are more harmonic at lower temperature. Intuitively,\nat high temperature, the collection of vibrational modes may be sufficient to\ndrive concerted ion hops. However, near room temperature, the vibrational modes\navailable may be insufficient to overcome electrostatic repulsion, thus\nresulting in less correlated ion motion and comparatively slower ion\nconduction. Such phenomena of a sublattice phase transition, below which\nconcerted hopping plays a less significant role, may be extended to other\nhighly concentrated solid electrolytes such as LLZO and LATP.",
        "positive": "Defect-Fluorite Gd2Zr2O7 Ceramics under Helium Irradiation:\n  Amorphization, Cell Volume Expansion, and Multi-stage Bubble Formation: Here, we report a study on the radiation resistance enhancement of Gd2Zr2O7\nnanograin ceramics, in which amorphization, cell volume expansion and\nmulti-stage helium (He) bubble formation are investigated and discussed.\nGd2Zr2O7 ceramics with a series of grain sizes (55-221 nm) were synthesized and\nirradiated by 190 keV He ion beam up to a fluence of 5x10^17 ions/cm2. Both the\ndegree of post irradiation cell volume expansion and the amorphization fraction\nappear to be size dependent. As the average grain size evolves from 55 to 221\nnm, the degree of post irradiation cell volume expansion increases from 0.56 to\n1.02 %, and the amorphization fraction increases from 6.8 to 11.1 %.\nAdditionally, the threshold He concentrations (at. %) of bubbles at different\nformation stages and locations, including (1) bubbles at grain boundary, (2)\nbubble-chains and (3) ribbon-like bubbles within the grain, are all found to be\nmuch higher in the nanograin ceramic (55 nm) compared with that of the\nsubmicron sample (221 nm). We conclude that grain boundary plays a critical\nrole in minimizing the structural defects, and inhibiting the multi-stage He\nbubble formation process."
    },
    {
        "anchor": "Electronic structure and self energies of randomly substituted solids\n  using density functional theory and model calculations: We describe procedures to obtain the electronic structure of disordered\nsystems using either tight binding like models or quite directly from ab inito\ndensity functional band structure calculations. The band structure is\ncalculated using super cells much larger than those containing a single\nminority component atom. We average over a large number of different super cell\ncalculations containing different randomly positioned minority component atoms\nin the super cell as well as a varying total number of minority component\natoms, weighted by the statistical probability. We develop an efficient and\nsimple algorithm for unfolding of these bands, based on Bloch's theorem. The\nunfolded band-structure obtained in this way exhibits momentum and energy\nbroadened structures replacing the gaps observed in often used single super\ncell calculations. Using the super cell averaged band-structure one can\nintroduce a self-energy, resulting from the scattering of randomly positioned\nalloy components. The self-energy is causal, and shows strong energy and some\nmomentum dependence. The self-energy shows rather non-trivial behavior and is\nin general non-zero at the Fermi-energy, resulting in an ill or undefined Fermi\nsurface. The real-part of the self-energy at the Fermi-energy relates to an\napparent violation of Luttinger's theorem. There is no simple relation between\nthe apparent Fermi-surface volume and the electron count. Examples introducing\nthese effects both for model and real binary alloy systems are presented.",
        "positive": "Improved Hopfield Network Optimization using Manufacturable\n  Three-terminal Electronic Synapses: We describe via simulation novel optimization algorithms for a Hopfield\nneural network constructed using manufacturable three-terminal\nSilicon-Oxide-Nitride-Oxide-Silicon (SONOS) synaptic devices. We first present\na computationally-light, memristor-based, highly accurate compact model for the\nSONOS. Using the compact model, we describe techniques of simulated annealing\nin Hopfield networks by exploiting imperfect problem definitions, current\nleakage, and the continuous tunability of the SONOS to enable transient chaotic\ngroup dynamics. We project improvements in energy consumption and latency for\noptimization relative to the best CPUs and GPUs by at least 4 orders of\nmagnitude, and also exceeding the best projected memristor-based hardware;\nalong with a 100-fold increase in error-resilient hardware size (i.e., problem\nsize)."
    },
    {
        "anchor": "Theoretical formation of carbon nanomembranes under realistic conditions\n  using classical molecular dynamics: Carbon nanomembranes made from aromatic precursor molecules are free standing\nnanometer thin materials of macroscopic lateral dimensions. Although produced\nin various versions for about two decades not much is known about their\ninternal structure. Here we present a first systematic theoretical attempt to\nmodel the formation, structure, and mechanical properties of carbon\nnanomembranes using classical molecular dynamics simulations. We find\ntheoretical production scenarios under which stable membranes form. They\npossess pores as experimentally observed. Their Young's modulus, however, is\nsystematically larger than experimentally determined.",
        "positive": "Fluorescent oxide nanoparticles adapted to active tips for near-field\n  optics: We present a new kind of fluorescent oxide nanoparticles with properties well\nsuited to active-tip based near-field optics. These particles with an average\ndiameter in the range 5-10 nm are produced by Low Energy Cluster Beam\nDeposition (LECBD) from a YAG:Ce3+ target. They are studied by transmission\nelectron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), classical\nphotoluminescence, cathodoluminescence and near-field scanning optical\nmicroscopy (NSOM). Particles of extreme photo-stability as small as 10 nm in\nsize are observed. These emitters are validated as building blocks of active\nNSOM tips by coating a standard optical tip with a 10 nm thick layer of\nYAG:Ce3+ particles directly in the LECBD reactor and by subsequently performing\nNSOM imaging of test surfaces."
    },
    {
        "anchor": "Melting of Partially Fluorinated Graphene: From Detachment of Fluorine\n  Atoms to Large Defects and Random Coils: The melting of fluorographene is very unusual and depends strongly on the\ndegree of fluorination. For temperatures below 1000 K, fully fluorinated\ngraphene (FFG) is thermo-mechanically more stable than graphene but at\nT$_m\\approx$2800 K FFG transits to random coils which is almost twice lower\nthan the melting temperature of graphene, i.e. 5300 K. For fluorinated graphene\n(PFG) up to 30 % ripples causes detachment of individual F-atoms around 2000 K\nwhile for 40-60 % fluorination, large defects are formed beyond 1500 K and\nbeyond 60% of fluorination F-atoms remain bonded to graphene until melting. The\nresults agree with recent experiments on the dependence of the reversibility of\nthe fluorination process on the percentage of fluorination.",
        "positive": "Theory of the phonon spectrum in host-guest crystalline solids with\n  avoided crossing: We develop an analytical model to describe the phonon dispersion relations of\nhost-guest lattices with heavy guest atoms (rattlers). Crucially, the model\nalso accounts for phonon damping arising from anharmonicity. The spectrum of\nlow energy states contains acoustic-like and (soft) optical-like modes, which\ndisplay the typical avoided crossing, and which can be derived analytically by\nconsidering the dynamical coupling between host lattice and guest rattlers.\nInclusion of viscous anharmonic damping in the model allows us, for the first\ntime, to compute the vibrational density of states (VDOS) and the specific\nheat, unveiling the presence of a boson peak (BP) linked to an\nanharmonicity-smeared van Hove singularity. Upon increasing the coupling\nstrength between the host and the guest dynamics, and by decreasing the energy\nof the soft optical modes, the BP anomaly becomes stronger and it moves towards\nlower frequencies. Moreover, we find a robust linear correlation between the BP\nfrequency and the energy of the soft optical-like modes. This framework\nprovides a useful model for tuning the thermal properties of host-guest\nlattices by controlling the VDOS, which is crucial for optimizing thermal\nconductivity and hence the energy conversion efficiency in these materials."
    },
    {
        "anchor": "Lithium adsorption properties of monolayer B$_5$Se: B$_5$Se this work we investigate the Li adsorption properties of a hybrid 2D\nmaterial, namely monolayer B5Se with first principles calculations. 2\ndimensional B$_5$Se was found to have a distorted hexagonal structure with five\nB atoms and one Se atom at the vertices of each hexagon. The density functional\ntheory (DFT) calculations are performed with the generalized gradient\napproximation (GGA) and Perdew-Burke-Ernzerhoff (PBE) exchange correlation\nfunctional. The results were inclusive of van der Waals corrections with\nGrimmes DFT-D2 scheme. Electrode performance metrics, as the most preferred\nadsorption sites and adsorption energies, open circuit anode potentials, charge\ndensity differences and specific capacities for varying adatom coverage were\nevaluated with the DFT calculations. The adatom diffusion barriers were\nevaluated with a nudged elastic band (NEB) method. The ab-initio calculations\npredict a maximum theoretical specific capacity of 1486.87 mAhg$^{-1}$ for Li\nadsorption on 2D B$_5$Se, which is over four times that of conventional Li ion\nbattery anode materials. This coupled with an open circuit anode potential of\n0.291-0.179V for different degrees of Li coverage, and a small Li diffusion\nbarrier of 0.15eV, metallic nature of the sheet under pure and lithiated\nconditions and good charge density variations, make monolayer B$_5$Se a potent\nanode material for Li-ion battery applications.",
        "positive": "Landau Theory of Barocaloric Plastic Crystals: We present a simple Landau phenomenology for plastic-to-crystal phase\ntransitions and use the resulting model to calculate barocaloric effects in\nplastic crystals that are driven by hydrostatic pressure. The essential\ningredients of the model are (i) a multipole-moment order parameter that\ndescribes the orientational ordering of the constituent molecules, (ii)\ncoupling between such order parameter and elastic strains, and (iii) the\nthermal expansion of the solid. The model captures main features of\nplastic-to-crystal phase transitions, namely large volume and entropy changes\nat the transition, and strong dependence of the transition temperature with\npressure. Using solid C$_{60}$ under $0.60\\,$GPa as case example, we show that\ncalculated peak isothermal entropy changes of $\\sim 58 \\,{\\rm J K^{-1}\nkg^{-1}}$ and peak adiabatic entropy changes of $\\sim 23 \\,{\\rm K}$ agree well\nwith experimental values."
    },
    {
        "anchor": "Dopants Promoting Ferroelectricity in Hafnia: Insights From A\n  Comprehensive Chemical Space Exploration: Although dopants have been extensively employed to promote ferroelectricity\nin hafnia films, their role in stabilizing the responsible ferroelectric\nnon-equilibrium Pca21 phase is not well understood. In this work, using first\nprinciples computations, we investigate the influence of nearly 40 dopants on\nthe phase stability in bulk hafnia to identify dopants that can favor formation\nof the polar Pca21 phase. Although no dopant was found to stabilize this polar\nphase as the ground state, suggesting that dopants alone cannot induce\nferroelectricity in hafnia, Ca, Sr, Ba, La, Y and Gd were found to\nsignificantly lower the energy of the polar phase with respect to the\nequilibrium monoclinic phase. These results are consistent with the empirical\nmeasurements of large remnant polarization in hafnia films doped with these\nelements. Additionally, clear chemical trends of dopants with larger ionic\nradii and lower electronegativity favoring the polar Pca21 phase in hafnia were\nidentified. For this polar phase, an additional bond between the dopant cation\nand the 2nd nearest oxygen neighbor was identified as the root-cause of these\ntrends. Further, trivalent dopants (Y, La, and Gd) were revealed to stabilize\nthe polar Pca21 phase at lower strains when compared to divalent dopants (Sr\nand Ba). Based on these insights, we predict that the lanthanide series metals,\nthe lower half of alkaline earth metals (Ca, Sr and Ba) and Y as the most\nsuitable dopants to promote ferroelectricity in hafnia.",
        "positive": "Spin-polarized saddle points in the topological surface states of the\n  elemental Bismuth revealed by a pump-probe spin-resolved ARPES: We use a pump-probe, spin-, and angle-resolved photoemission spectroscopy\n(ARPES) with a 10.7 eV laser accessible up to the Brillouin zone edge, and\nreveal for the first time the entire band structure, including the unoccupied\nside, for the elemental bismuth (Bi) with the spin-polarized surface states.\nOur data identify Bi as in a strong topological insulator phase ($Z_2$=1)\nagainst the prediction of most band calculations. We unveil that the unoccupied\ntopological surface states possess spin-polarized saddle points yielding the\nvan Hove singularity, providing an excellent platform for the future\ndevelopment of opto-spintronics."
    },
    {
        "anchor": "Chlorine doping of MoSe2 flakes by ion implantation: The efficient integration of transition metal dichalcogenides (TMDs) into the\ncurrent electronic device technology requires mastering the techniques of\neffective tuning of their optoelectronic properties. Specifically, controllable\ndoping is essential. For conventional bulk semiconductors, ion implantation is\nthe most developed method offering stable and tunable doping. In this work, we\ndemonstrate n-type doping in MoSe2 flakes realized by low-energy ion\nimplantation of Cl+ ions followed by millisecond-range flash lamp annealing\n(FLA). We further show that FLA for 3 ms with a peak temperature of about 1000\n{\\deg}C is enough to recrystallize implanted MoSe2. The Cl distribution in\nfew-layer-thick MoSe2 is measured by secondary ion mass spectrometry. An\nincrease in the electron concentration with increasing Cl fluence is determined\nfrom the softening and red shift of the Raman-active A_1g phonon mode due to\nthe Fano effect. The electrical measurements confirm the n-type doping of\nCl-implanted MoSe2. A comparison of the results of our density functional\ntheory calculations and experimental temperature-dependent micro-Raman\nspectroscopy data indicates that Cl atoms are incorporated into the atomic\nnetwork of MoSe2 as substitutional donor impurities.",
        "positive": "Magnetic Phase Diagram of CuO: High resolution ultrasonic velocity measurements have been used to determine\nthe temperature -- magnetic-field phase diagram of the monoclinic multiferroic\nCuO. A new transition at TN3 = 230 K, corresponding to an intermediate state\nbetween the antiferromagnetic non-collinear spiral phase observed below TN2 =\n229.3 K and the paramagnetic phase, is revealed. Anomalies associated with a\nfirst order transition to the commensurate collinear phase are also observed at\nTN1 = 213 K. For fields with B along the b axis, a spin-flop transition is\ndetected between 11 T - 13 T at lower temperatures. Moreover, our analysis\nusing a Landau-type free energy clearly reveals the necessity for an\nincommensurate collinear phase between the spiral and the paramagnetic phase.\nThis model is also relevant to the phase diagrams of other monoclinic\nmultiferroic systems."
    },
    {
        "anchor": "Bulk metallic glass-like structure of small icosahedral metallic\n  nanoparticles: We demonstrate a remarkable equivalence in structure measured by total X-ray\nscattering methods between very small metallic nanoparticles and bulk metallic\nglasses (BMGs), thus connecting two disparate fields, shedding new light on\nboth. Our results show that for nanoparticle diameters <5 nm the structure of\nNi nanoparticles changes from fcc to the characteristic BMG-like structure,\ndespite them being formed from a single element, an effect we call\nnano-metallic glass (NMG) formation. However, high-resolution TEM images of the\nNMG clusters exhibit lattice fringes indicating a locally well-ordered, rather\nthan glassy, structure. These seemingly contradictory results may be reconciled\nby finding a locally ordered structure that is highly isotropic and we show\nthat local icosahedral packing within 5 atomic shells explains this. Since this\nstructure is stabilized only in the vicinity of a surface which highlights the\nimportance of the presence of free volume in BMGs for stabilizing similar local\nclusters.",
        "positive": "Morphological and Structural Characterization of Cro2/Cr2o3 Films Grown\n  by Laser-CVD: This work reports on the synthesis of chromium (III, IV) oxides films by KrF\nlaser-assisted CVD. Films were deposited onto sapphire substrates at room\ntemperature by photodissociation of Cr(CO)6 in dynamic atmospheres containing\noxygen and argon. A study of the processing parameters has shown that partial\npressure ratio of O2 to Cr(CO)6 and laser fluence are the prominent parameters\nthat have to be accurately controlled in order to co-deposit both crystalline\noxide phases. Films consistent with such a two-phase system were synthesised\nfor a laser fluence of 75 mJ cm-2 and a partial pressure ratio about 1.\n  PACS: 81.15.Fg, 81.15.Kk, 81.05.Je"
    },
    {
        "anchor": "Polyconvex anisotropic hyperelasticity with neural networks: In the present work, two machine learning based constitutive models for\nfinite deformations are proposed. Using input convex neural networks, the\nmodels are hyperelastic, anisotropic and fulfill the polyconvexity condition,\nwhich implies ellipticity and thus ensures material stability. The first\nconstitutive model is based on a set of polyconvex, anisotropic and objective\ninvariants. The second approach is formulated in terms of the deformation\ngradient, its cofactor and determinant, uses group symmetrization to fulfill\nthe material symmetry condition, and data augmentation to fulfill objectivity\napproximately. The extension of the dataset for the data augmentation approach\nis based on mechanical considerations and does not require additional\nexperimental or simulation data. The models are calibrated with highly\nchallenging simulation data of cubic lattice metamaterials, including finite\ndeformations and lattice instabilities. A moderate amount of calibration data\nis used, based on deformations which are commonly applied in experimental\ninvestigations. While the invariant-based model shows drawbacks for several\ndeformation modes, the model based on the deformation gradient alone is able to\nreproduce and predict the effective material behavior very well and exhibits\nexcellent generalization capabilities. In addition, the models are calibrated\nwith transversely isotropic data, generated with an analytical polyconvex\npotential. For this case, both models show excellent results, demonstrating the\nstraightforward applicability of the polyconvex neural network constitutive\nmodels to other symmetry groups.",
        "positive": "Charge transport across metal/molecular (alkyl) monolayer-Si junctions\n  is dominated by the LUMO level: We compare the charge transport characteristics of heavy doped p- and\nn-Si-alkyl chain/Hg junctions. Photoelectron spectroscopy (UPS, IPES and XPS)\nresults for the molecule-Si band alignment at equilibrium show the Fermi level\nto LUMO energy difference to be much smaller than the corresponding Fermi level\nto HOMO one. This result supports the conclusion we reach, based on negative\ndifferential resistance in an analogous semiconductor-inorganic insulator/metal\njunction, that for both p- and n-type junctions the energy difference between\nthe Fermi level and LUMO, i.e., electron tunneling, controls charge transport.\nThe Fermi level-LUMO energy difference, experimentally determined by IPES,\nagrees with the non-resonant tunneling barrier height deduced from the\nexponential length-attenuation of the current."
    },
    {
        "anchor": "Surface Reactivity and Quantum-Size effects on the Electronic Density\n  Decay Length of ultrathin Metal Films: The origin of the correlation between surface reactivity and quantum-size\neffects, observed in recent experiments on the oxidation of ultrathin magnesium\nfilms, is addressed by means of ab-initio calculations and model predictions.\nWe show that the decay length in vacuum of the electronic local density of\nstates at the Fermi energy exhibits systematic oscillations with film\nthickness, with local maxima induced when a quantum well state at k// = 0\ncrosses the Fermi energy. The predicted changes in the decay length are\nexpected to have a major impact on the electron transfer rate by tunneling,\nwhich has been proposed to control the initial sticking of O2 in the oxidation\nprocess.",
        "positive": "$\u03b3$-phase Inclusions as Common Defects in Alloyed\n  $\u03b2$-(Al$_x$Ga$_{1\\text{-}x}$)$_2$O$_3$ and Doped $\u03b2$-Ga$_2$O$_3$\n  Films: $\\beta$-Ga$_2$O$_3$ is a promising ultra-wide bandgap semiconductor whose\nproperties can be further enhanced by alloying with Al. Here, using\natomic-resolution scanning transmission electron microscopy (STEM), we find the\nthermodynamically-unstable $\\gamma$-phase is a ubiquitous defect in both\n$\\beta$-(Al$_x$Ga$_{1\\text{-}x}$)$_2$O$_3$ films and doped $\\beta$-Ga$_2$O$_3$\nfilms grown by molecular beam epitaxy. For undoped\n$\\beta$-(Al$_x$Ga$_{1\\text{-}x}$)$_2$O$_3$ films we observe $\\gamma$-phase\ninclusions between nucleating islands of the $\\beta$-phase at lower growth\ntemperatures (~400-600 $^{\\circ}$C). In doped $\\beta$-Ga$_2$O$_3$, a thin layer\nof the $\\gamma$-phase is observed on the surfaces of films grown with a wide\nrange of n-type dopants and dopant concentrations. The thickness of the\n$\\gamma$-phase layer was most strongly correlated with the growth temperature,\npeaking at about 600 $^{\\circ}$C. Ga interstitials are observed in\n$\\beta$-phase, especially near the interface with the $\\gamma$-phase. By\nimaging the same region of the surface of a Sn-doped\n$\\beta$-(Al$_x$Ga$_{1\\text{-}x}$)$_2$O$_3$ after ex-situ heating up to 400\n$^{\\circ}$C, a $\\gamma$-phase region is observed to grow above the initial\nsurface, accompanied by a decrease in Ga interstitials in the $\\beta$-phase.\nThis suggests that the diffusion of Ga interstitials towards the surface is\nlikely the mechanism for growth of the surface $\\gamma$-phase, and more\ngenerally that the more-open $\\gamma$-phase may offer diffusion pathways to be\na kinetically-favored and early-forming phase in the growth of Ga$_2$O$_3$."
    },
    {
        "anchor": "Granular Matter: a wonderful world of clusters in far-from-equilibrium\n  systems: In this paper, we recall various features of non equilibrium granular\nsystems. Clusters with specific properties are found depending on the packing\ndensity, going from loose (a granular gas) to sintered (though brittle)\npolycrystalline materials. The phase space available can be quite different.\nUnexpected features, with respect to standard or expected ones in classical\nfluids or solids, are observed, - like slow relaxation processes or anomalous\nelectrical and thermoelectrical transport property dependences. The cases of\nvarious pile structures and the interplay between classical phase transitions\nand self-organized criticality for avalanches are also outlined.",
        "positive": "Excitonic properties of semiconducting monolayer and bilayer MoTe2: MoTe2 belongs to the semiconducting transition metal dichalcogenide family\nwith some properties differing from the other well-studied members\n(Mo,W)(S,Se)2. The optical band gap is in the near infrared region and both\nmonolayers and bilayers may have a direct optical band gap. We first simulate\nthe band structure of both monolayer and bilayer MoTe2 with DFT-GW\ncalculations. We find a direct (indirect) electronic band gap for the monolayer\n(bilayer). By solving the Bethe-Salpeter equation, we calculate similar\nenergies for the direct excitonic states in monolayer and bilayer. We then\nstudy the optical properties by means of photoluminescence (PL) excitation,\ntime-resolved PL and power dependent PL spectroscopy. We identify the same\nenergy for the B exciton state in monolayer and bilayer. Following circularly\npolarized excitation, we do not find any exciton polarization for a large range\nof excitation energies. At low temperature (T=10 K), we measure similar PL\ndecay times of the order of 4 ps for both monolayer and bilayer excitons with a\nslightly longer one for the bilayer. Finally, we observe a reduction of the\nexciton-exciton annihilation contribution to the non-radiative recombination in\nbilayer."
    },
    {
        "anchor": "High-order harmonic generation in solid $\\rm \\bf C_{60}$: High harmonic generation (HHG) has unleashed the power of strong laser\nphysics in solids. Here we investigate HHG from a large system, solid C$_{60}$,\nwith 240 valence electrons engaging harmonic generation at each crystal\nmomentum, the first of this kind. We employ the density functional theory and\nthe time-dependent Liouville equation of the density matrix to compute HHG\nsignals. We find that under a moderately strong laser pulse, HHG signals reach\n15th order, consistent with the experimental results from C$_{60}$ plasma. The\nhelicity dependence in solid C$_{60}$ is weak, due to the high symmetry. In\ncontrast to the general belief, HHG is unsuitable for band structure mapping in\nC$_{60}$. However, we find a window of opportunity using a long wavelength,\nwhere harmonics are generated through multiple-photon excitation. In\nparticular, the 5th order harmonic energies closely follow the transition\nenergy dispersion between the valence and conduction bands. This finding is\nexpected to motivate future experimental investigations.",
        "positive": "Electronic and structural properties of 3D Hopf-linked carbon allotrope:\n  Hopfene: Electronic and structural properties of a 3D carbon allotrope made of\nHopf-linked graphenes, which we call a Hopfene - a type of topological crystal,\nare examined by semi-empirical molecular-orbital and\ndensity-functional-theoretical methods, where band-structure analyses reveal\nvery different properties from those of 2D graphenes. Furthermore, the analyses\ngive an interesting finding that, depending on graphene-sheet spacings,\nHopfenes exhibit different band features between primary-type Hopfene with a\nfinite minimum sheet spacing and secondary type with its double-sized spacing.\nThe primary type shows semi-metallic nature and the secondary type exhibits\nsemi-metallic or semiconducting nature at different bands and also has flat\nbands; these conducting features can be utilised by Fermi-level control. A\ndevice application of Hopfenes is also provided."
    },
    {
        "anchor": "Quantitative disentanglement of coherent and incoherent laser-induced\n  surface deformations by time-resolved x-ray reflectivity: We present time-resolved x-ray reflectivity measurements on laser excited\ncoherent and incoherent surface deformations of thin metallic films. Based on a\nkinematical diffraction model, we derive the surface amplitude from the\ndiffracted x-ray intensity and resolve transient surface excursions with\nsub-Angstrom spatial precision and 70 ps temporal resolution. The novel\nanalysis allows for decomposition of the surface amplitude into multiple\ncoherent acoustic modes and a substantial contribution from incoherent phonons\nwhich constitute the sample heating.",
        "positive": "Discovery of Hidden Classes of Layered Electrides by Extensive\n  High-throughput Materials Screening: Despite their extraordinary properties, electrides are still a relatively\nunexplored class of materials with only a few compounds grown experimentally.\nEspecially for layered electrides, the current researches mainly focus on\nseveral isostructures of Ca2N with similar interlayer two-dimensional (2D)\nanionic electrons. An extensive screening for different layered electrides is\nstill missing. Here, by screening materials with anionic electrons for the\nstructures in Materials Project, we uncover 12 existing materials as new\nlayered electrides. Remarkably, these layered electrides demonstrate completely\ndifferent properties from Ca2N. For example, unusual fully spin-polarized\nzero-dimensional (0D) anionic electrons are shown in metal halides with\nMoS2-like structures; unique one-dimensional (1D) anionic electrons are\nconfined within the tubes of the quasi-1D structures; a coexistence of magnetic\nand non-magnetic anionic electrons is found in ZrCl-like structures and a new\nternary Ba2LiN with both 0D and 1D anionic electrons. These materials not only\nsignificantly increase the pool of experimentally synthesizable layered\nelectrides but also are promising to be exfoliated into advanced 2D materials."
    },
    {
        "anchor": "Effect of substitutional doping and disorder on the phase stability,\n  magnetism, and half-metallicity of Heusler alloys: Spintronics is the fast growing field that will play a key role in optimizing\npower consumption, memory, and processing capabilities of nanoelectronic\ndevices. Heusler alloys are potential candidates for application in spintronics\ndue to their room temperature (RT) half-metallicity, high Curie temperature,\nlow lattice mismatch with most substrates, and strong control on electronic\ndensity of states at Fermi level. In this work, we investigate the effect of\n{substitutional doping and disorder} on the half-metallicity, phase stability,\nand magnetism of Heusler alloys using density functional theory methods. Our\nstudy shows that electronic and magnetic properties of half/full-Heusler alloys\ncan be tuned by changing electron-count through controlled variation of\nchemical compositions of alloying elements. We provide a detailed discussion on\nthe effect of substitutional doping and disorder on the tunability of\nhalf-metallic nature of Co$_{2}$MnX and NiMnX based Heusler alloys, where X\nrepresents group 13\\textendash 16 and period 3\\textendash 6 elements of the\nperiodic table. {Based on the idea of electron count and disorder, we predicted\na possible existence of thermodynamically stable half-metallic multicomponent\nbismuthides, for example, (CuNi$_{3}$)Mn$_{4}$Bi$_{4}$ and\n(ZnNi$_{7}$)Mn$_{8}$Bi$_{8}$, through substitution doping at Ni site by\nspecific Cu and Zn composition in half-Heusler NiMnBi.} We believe that the\ndesign guide {based on electron-counts} presented for half-metals will play a\nkey role in electronic-structure engineering of novel Heusler alloys for\nspintronic application, which will accelerate the development and synthesis of\nnovel materials.",
        "positive": "Ab initio calculations of the concentration dependent band gap reduction\n  in dilute nitrides: While being of persistent interest for the integration of lattice-matched\nlaser devices with silicon circuits, the electronic structure of dilute nitride\nIII/V-semiconductors has presented a challenge to ab initio computational\napproaches. The root of this lies in the strong distortion N atoms exert on\nmost host materials. Here, we resolve these issues by combining density\nfunctional theory calculations based on the meta-GGA functional presented by\nTran and Blaha (TB09) with a supercell approach for the dilute nitride Ga(NAs).\nExploring the requirements posed to supercells, we show that the distortion\nfield of a single N atom must be allowed to decrease so far, that it does not\noverlap with its periodic images. This also prevents spurious electronic\ninteractions between translational symmetric atoms, allowing to compute band\ngaps in very good agreement with experimentally derived reference values. These\nresults open up the field of dilute nitride compound semiconductors to\npredictive ab initio calculations."
    },
    {
        "anchor": "Systematic investigation of the deformation mechanisms of a\n  \u03b3-TiAl single crystal: We propose a theoretical framework to predict the deformation mechanism of\nthe {\\gamma}-TiAl single crystal without lattice defects by combining the\ngeneralized stacking fault energy and the Schmid factor. Our theory is\nvalidated against an excellent testbed, the single crystal nanowire, by\ncorrectly predicting four major deformation mechanisms, namely, ordinary slip,\nsuper slip, twinning, and mixed slip/fracture observed during the tensile and\ncompressive tests along 10 different orientations using molecular dynamics\nsimulations. Interestingly, although lattice defects are not taken into\naccount, the theoretical predictions match well with existing experiments on\nbulk specimen with only a few exceptions; the exceptions are discussed based on\nthe size-dependent deformation mechanism in the presence of preexisting\ndislocation sources. We expect that the method in this paper can be generalized\nto study various ductile intermetallic crystals where conventional Schmid law\ndoes not hold well.",
        "positive": "Spin symmetry and spin current of helicity eigenstates of the Luttinger\n  Hamiltonian: A general spin symmetry argument is proposed for spin currents in\nsemiconductors. In particular, due to the symmetry with respect to spin\npolarization of the helicity eigenstates of the Luttinger Hamiltonian for a\nhole-doped semiconductor, the spin polarized flux from a single helicity\neigenstate induced by an external electric field, is canceled exactly when all\nsuch contributions from eigenstates that are degenerate in energy are summed.\nThus, the net spin current predicted by Murakami et al, Science 301, 1348\n(2003), cannot be produced by such a Hamiltonian. Possible symmetry breaking\nmechanisms which may generate a spin current are discussed."
    },
    {
        "anchor": "Non-stationary thermophysical characterization of exfoliated graphite\n  with carbon nanotubes composites: The sheet samples of thermally exfoliated graphite (TEG) carbon nanotubes\n(CNT) composites (TEG CNT cs) were obtained by persulphate oxidation using\nchemical (CO) and electrochemical (anode) oxidation (ECAO). Electron microscopy\nreveals multi layered structures of few layer graphene nanosheets with folded\nand tubular like fragments.Electron microscopy reveals multilayered structures\nof few layer graphene nanosheets with folded and tubular like fragments. The\neffective thermal diffusivity values were estimated by nonstationary\nphoto-pyroelectric thermophysical characterization using the heat pulse and\nthermo-wave modulation methods. Comparison with other carbon (C) based thermal\nmanagement materials shows that TEG CNTcs exhibit thermal diffusivity,\neffusivity and conductivity comparable with those of actual C polymer and C C\ncomposites. For TEG CNT cs, evaluated values of phonon mean free path (MFP) and\nrelaxation time (RT) are in the ranges estimated for defective graphene. The\nvalues of diffusivity and effusivity, MFP and RT are lower for denser TEG CNT\ncs obtained by ECAO and are higher for less dense TEG CNT cs obtained by CO.\nThe obtained diffusivity and effusivity values designate TEG CNT cs as suitable\nthermal management materials.",
        "positive": "Coupled Valence Carrier and Core-Exciton Dynamics in WS$_{2}$ Probed by\n  Few-Femtosecond Extreme Ultraviolet Transient Absorption Spectroscopy: Few-femtosecond extreme ultraviolet (XUV) transient absorption spectroscopy,\nperformed with optical 500-1000 nm supercontinuum and broadband XUV pulses\n(30-50 eV), simultaneously probes dynamics of photoexcited carriers in WS$_{2}$\nat the W O$_3$ edge (37-45 eV) and carrier-induced modifications of\ncore-exciton absorption at the W N$_{6,7}$ edge (32-37 eV). Access to\ncontinuous core-to-conduction band absorption features and discrete\ncore-exciton transitions in the same XUV spectral region in a semiconductor\nprovides a novel means to investigate the effect of carrier excitation on\ncore-exciton dynamics. The core-level transient absorption spectra, measured\nwith either pulse arriving first to explore both core-level and valence carrier\ndynamics, reveal that core-exciton transitions are strongly influenced by the\nphotoexcited carriers. A $1.2\\pm0.3$ ps hole-phonon relaxation time and a\n$3.1\\pm0.4$ ps carrier recombination time are extracted from the XUV transient\nabsorption spectra from the core-to-conduction band transitions at the W\nO$_{3}$ edge. Global fitting of the transient absorption signal at the W\nN$_{6,7}$ edge yields $\\sim 10$ fs coherence lifetimes of core-exciton states\nand reveals that the photoexcited carriers, which alter the electronic\nscreening and band filling, are the dominant contributor to the spectral\nmodifications of core-excitons and direct field-induced changes play a minor\nrole. This work provides a first look at the modulations of core-exciton states\nby photoexcited carriers and advances our understanding of carrier dynamics in\nmetal dichalcogenides."
    },
    {
        "anchor": "Spin polarized STM imaging of nanoscale N\u00e9el skyrmions in an\n  SrIrO3/SrRuO3 Perovskite Bilayer: Spin-polarized scanning tunneling microscopy (SPSTM) was used to directly\nimage nanoscale N\\'eel skyrmions in a SrIrO3 / SrRuO3 bilayer system that are\namong the smallest reported to date in any system. Off-axis magnetron\nsputtering was used to cap epitaxial films of the oxide ferromagnet SRO with 2\nunit cells of SrIrO3, intended to provide interfacial spin orbit coupling.\nAtomic resolution STM imaging and tunneling spectroscopy were used to identify\nisland-like SrIrO3 grains and small regions of bare SrRuO3. Isolated skyrmions\nwere only observed in SrIrO3-covered regions of the film, and exhibited a\ndistribution of sizes and shapes with an average diameter of 3 nm. We found\nthat skyrmions must be fully contained within, but may be smaller than, any\ngiven SrIrO3 region. Additionally, skyrmions were observed on SrIrO3 islands of\nvarying thickness without loss of SPSTM contrast, suggesting the magnetic\ntexture lies within the SrIrO3 island rather than the underlying ferromagnetic\nSrRuO3. Density functional theory calculations suggest this could be due to a\nsmall induced magnetic moment associated with IrO layers in the SrIrO3 film.",
        "positive": "Estimating yield-strain via deformation-recovery simulations: In computational materials science, predicting the yield strain of\ncrosslinked polymers remains a challenging task. A common approach is to\nidentify yield as the first critical point of stress-strain curves simulated by\nmolecular dynamics (MD). However, in such cases the underlying data can be\nexcessively noisy, making it difficult to extract meaningful results. In this\nwork, we propose an alternate method for identifying yield on the basis of\ndeformation-recovery simulations. Notably, the corresponding raw data (i.e.\nresidual strains) produce a sharper signal for yield via a transition in their\nglobal behavior. We analyze this transition by non- linear regression of\ncomputational data to a hyperbolic model. As part of this analysis, we also\npropose uncertainty quantification techniques for assessing when and to what\nextent the simulated data is informative of yield. Moreover, we show how the\nmethod directly tests for yield via the onset of permanent deformation and\ndiscuss recent experimental results, which compare favorably with our\npredictions."
    },
    {
        "anchor": "Thermal contribution to the spin-orbit torque in metallic/ferrimagnetic\n  systems: We report a systematic study of current-induced perpendicular magnetization\nswitching in W/Co$_{x}$Tb$_{1-x}$/Al thin films with strong perpendicular\nmagnetic anisotropy. Various Co$_{x}$Tb$_{1-x}$ ferrimagnetic alloys with\ndifferent magnetic compensation temperatures are presented. The systems are\ncharacterized using MOKE, SQUID and anomalous Hall resistance at different\ncryostat temperature ranging from 10 K to 350 K. The current-switching\nexperiments are performed in the spin-orbit torque geometry where the current\npulses are injected in plane and the magnetization reversal is detected by\nmeasuring the Hall resistance. The full reversal magnetization has been\nobserved in all samples. Some experimental results could only be explained by\nthe strong sample heating effect during the current pulses injection. We have\nfound that, for a given composition $x$ and switching polarity, the devices\nalways reach the same temperature $\\textit{T}_{switch}(x)$ before switching\nindependently of the cryostat temperature. $\\textit{T}_{switch}$ seems to scale\nwith the Curie temperature of the Co$_{x}$Tb$_{1-x}$ ferrimagnetic alloys. This\nexplains the evolution of the critical current (and critical current density)\nas a function of the alloy concentration. Future application could take\nadvantages of this heating effect which allows reducing the in-plane external\nfield. Unexpected double magnetization switching has been observed when the\nheat generated by the current allows crosses the compensation temperature.",
        "positive": "First principles thermodynamical modeling of the binodal and spinodal\n  curves in lead chalcogenides: High-throughput ab-initio calculations, cluster expansion techniques and\nthermodynamic modeling have been synergistically combined to characterize the\nbinodal and the spinodal decompositions features in the pseudo-binary lead\nchalcogenides PbSe-PbTe, PbS-PbTe, and PbS-PbSe. While our results agree with\nthe available experimental data, our consolute temperatures substantially\nimprove with respect to previous computational modeling. The computed phase\ndiagrams corroborate that the formation of spinodal nanostructures causes low\nthermal conductivities in these alloys. The presented approach, making a\nrational use of online quantum repositories, can be extended to study\nthermodynamical and kinetic properties of materials of technological interest."
    },
    {
        "anchor": "Direct evidence of electron-hole compensation for XMR in topologically\n  trivial YBi: The prediction of topological states in rare earth monopnictide compounds has\nattracted renewed interest. Extreme magnetoresistance (XMR) has also been\nobserved in several nonmagnetic rare earth monopnictide compounds. The origin\nof XMR in these compounds could be attributed to several mechanisms, such as\ntopologically nontrivial electronic structures and electron-hole carrier\nbalance. YBi is a typical rare earth monopnictide exhibiting XMR, and expected\nto have a nontrivial electronic structure. In this work, we performed a direct\ninvestigation of the electronic structure of YBi by combining angle resolved\nphotoemission spectroscopy and theoretical calculations. Our results show that\nYBi is topologically trivial without the expected band inversion, and they rule\nout the topological effect as the cause of XMR in YBi. Furthermore, we directly\nobserved perfect electron-hole compensation in the electronic structure of YBi,\nwhich could be the primary mechanism accounting for the XMR.",
        "positive": "An augmented space approach to the study of phonons in disordered alloys\n  : comparison between the itinerant coherent-potential approximation and the\n  augmented space recursion: A first principles density functional based linear response theory (the so\ncalled Density Functional Perturbation theory \\cite{dfpt}) has been combined\nseparately with two recently developed formalism for a systematic study of the\nlattice dynamics in disordered binary alloys. The two formalisms are the\nAugmented space recursion (ASR) and the Itinerant coherent potential\napproximation (ICPA). The two different theories (DFPT-ASR and DFPT-ICPA)\nsystematically provides a hierarchy of improvements upon the earlier single\nsite based theories (like CPA etc.) and includes non-local correlations in the\ndisorder configurations. The formalisms explicitly take into account\nfluctuations in masses, force constants and scattering lengths. The combination\nof DFPT with these formulation helps in understanding the actual interplay of\nforce constants in alloys. We illustrate the methods by applying to a fcc\nFe$_{50}$Pd$_{50}$ alloy."
    },
    {
        "anchor": "Creating stable Floquet-Weyl semimetals by laser-driving of 3D Dirac\n  materials: Tuning and stabilising topological states, such as Weyl semimetals, Dirac\nsemimetals, or topological insulators, is emerging as one of the major topics\nin materials science. Periodic driving of many-body systems offers a platform\nto design Floquet states of matter with tunable electronic properties on\nultrafast time scales. Here we show by first principles calculations how\nfemtosecond laser pulses with circularly polarised light can be used to switch\nbetween Weyl semimetal, Dirac semimetal, and topological insulator states in a\nprototypical 3D Dirac material, Na$_3$Bi. Our findings are general and apply to\nany 3D Dirac semimetal. We discuss the concept of time-dependent bands and\nsteering of Floquet-Weyl points (Floquet-WPs), and demonstrate how light can\nenhance topological protection against lattice perturbations. Our work has\npotential practical implications for the ultrafast switching of materials\nproperties, like optical band gaps or anomalous magnetoresistance. Moreover, we\nintroduce Floquet time-dependent density functional theory (Floquet-TDDFT) as a\ngeneral and robust first principles method for predictive Floquet engineering\nof topological states of matter.",
        "positive": "Anisotropy of spin relaxation in metals: The concept of anisotropy of spin relaxation in non-magnetic metals with\nrespect to the spin direction of the injected electrons relative to the crystal\norientation is introduced. The effect is related to an anisotropy of the\nElliott-Yafet parameter, arising from a modulation of the decomposition of the\nspin-orbit Hamiltonian into spin-conserving and spin-flip terms as the spin\nquantization axis is varied. This anisotropy, reaching gigantic values for\nuniaxial transition-metals (e.g. 830% for hcp Hf) as density-functional\ncalculations show, is related to extended \"spin-flip hot areas\" on the Fermi\nsurface created by the proximity of extended sheets of the surface, or\n\"spin-flip hot loops\" at the Brillouin zone boundary, and has no theoretical\nupper limit. Possible ways of measuring the effect as well as consequences in\napplication are briefly outlined."
    },
    {
        "anchor": "Spin coherence and dephasing of localized electrons in monolayer MoS$_2$: We report a systematic study of coherent spin precession and spin dephasing\nin electron-doped monolayer MoS$_2$. Using time-resolved Kerr rotation\nspectroscopy and applied in-plane magnetic fields, a nanosecond-timescale\nLarmor spin precession signal commensurate with $g$-factor $|g_0|\\simeq 1.86$\nis observed in several different MoS$_2$ samples grown by chemical vapor\ndeposition. The dephasing rate of this oscillatory signal increases linearly\nwith magnetic field, suggesting that the coherence arises from a sub-ensemble\nof localized electron spins having an inhomogeneously-broadened distribution of\n$g$-factors, $g_0 + \\Delta g$. In contrast to $g_0$, $\\Delta g$ is\nsample-dependent and ranges from 0.042 to 0.115.",
        "positive": "Stacking Faults Assist Lithium-Ion Conduction in a Halide-Based\n  Superionic Conductor: In the pursuit of urgently-needed, energy dense solid-state batteries for\nelectric vehicle and portable electronics applications, halide solid\nelectrolytes offer a promising path forward with exceptional compatibility\nagainst high-voltage oxide electrodes, tunable ionic conductivities, and facile\nprocessing. For this family of compounds, synthesis protocols strongly affect\ncation site disorder and modulate Li+ mobility. In this work, we reveal the\npresence of a high concentration of stacking faults in the superionic conductor\nLi3YCl6 and demonstrate a method of controlling its Li+ conductivity by tuning\nthe defect concentration with synthesis and heat treatments at select\ntemperatures. Leveraging complementary insights from variable temperature\nsynchrotron X-ray diffraction, neutron diffraction, cryogenic transmission\nelectron microscopy, solid-state nuclear magnetic resonance, density functional\ntheory, and electrochemical impedance spectroscopy, we identify the nature of\nplanar defects and the role of nonstoichiometry in lowering Li+ migration\nbarriers and increasing Li site connectivity in mechanochemically-synthesized\nLi3YCl6. We harness paramagnetic relaxation enhancement to enable 89Y\nsolid-state NMR, and directly contrast the Y cation site disorder resulting\nfrom different preparation methods, demonstrating a potent tool for other\nresearchers studying Y-containing compositions. With heat treatments at\ntemperatures as low as 333 K (60{\\deg}C), we decrease the concentration of\nplanar defects, demonstrating a simple method for tuning the Li+ conductivity.\nFindings from this work are expected to be generalizable to other halide solid\nelectrolyte candidates and provide an improved understanding of defect-enabled\nLi+ conduction in this class of Li-ion conductors."
    },
    {
        "anchor": "Two-dimensional binary transition metal nitride $M$N$_4$ ($M$ = V, Cr,\n  Mn, Fe, Co) with a graphene-like structure and strong magnetic properties: Binary transition metal nitride with a graphene-like structure and strong\nmagnetic properties is rare. Based on the first-principles calculations, we\ndesign two kinds of $M$N$_4$ ($M$ =transition metal) monolayers, which are\ntransition metal nitrides with a planar structure, made up of $M$N$_4$ units\naligned in the rhombic and square patterns. The two structural lattices have\nrobust stability and good compatibility with different metal atoms, and the\nunderlying mechanism is the combination of $sp^2$ hybridization, coordinate\nbond, and $\\pi$ conjugation. With the metal atom changing from V, Cr, Mn, Fe to\nCo, the total charge of $M$N$_4$ system increases by one electron in turn,\nwhich results in continuous adjustability of the electronic and magnetic\nproperties. The planar ligand field is another feature of the two $M$N$_4$\nlattices, which brings about the special splitting of five suborbitals of 3$d$\nmetal atom and gives rise to strong magnetism. Moreover, room-temperature\nferromagnetism in square-CoN$_4$ monolayer with the Curie temperatures of 321 K\nis determined by solving the Heisenberg model combined with Monte Carlo method.",
        "positive": "Comment on ``Solidification of a Supercooled Liquid in a Narrow\n  Channel'': Comment on PRL v. 86, p. 5084 (2001) [cond-mat/0101016]. We point out that\nthe authors' simulations are consistent with the known theory of steady-state\nsolutions in this system."
    },
    {
        "anchor": "Magnetic anisotropy of the van der Waals ferromagnet Cr$_2$Ge$_2$Te$_6$\n  studied by angular-dependent XMCD: The van der Waals ferromagnet Cr$_2$Ge$_2$Te$_6$ (CGT) has a two-dimensional\ncrystal structure where each layer is stacked through van der Waals force. We\nhave investigated the nature of the ferromagnetism and the weak perpendicular\nmagnetic anisotropy (PMA) of CGT by means of X-ray absorption spectroscopy and\nX-ray magnetic circular dichroism (XMCD) studies of CGT single crystals. The\nXMCD spectra at the Cr $L_{2,3}$ edge for different magnetic field directions\nwere analyzed on the basis of the cluster-model multiplet calculation. The Cr\nvalence is confirmed to be 3+ and the orbital magnetic moment is found to be\nnearly quenched, as expected for the high-spin $t_{2g}$$^3$ configuration of\nthe Cr$^{3+}$ ion. A large ($\\sim 0.2$ eV) trigonal crystal-field splitting of\nthe $t_{2g}$ level caused by the distortion of the CrTe$_6$ octahedron has been\nrevealed, while the single-ion anisotropy (SIA) of the Cr atom is found to have\na sign {\\it opposite} to the observed PMA and too weak compared to the reported\nanisotropy energy. The present result suggests that anisotropic exchange\ncoupling between the Cr atoms through the ligand Te $5p$ orbitals having strong\nspin-orbit coupling has to be invoked to explain the weak PMA of CGT, as in the\ncase of the strong PMA of CrI$_3$.",
        "positive": "Thermodynamic and corrosion study of Sm$_{1-x}$Mg$_x$Ni$_y$ (y = 3.5 or\n  3.8) compounds forming reversible hydrides: AB5 compounds (A = rare earth, B = transition metal) have been widely studied\nas anodes for Ni-MH applications. However, they have reached their technical\nlimitations and the search for new promising materials with high capacity is\nforeseen. ABy compounds (2 < y < 5) are good candidates. They are made by\nstacking [AB5] and [A2B4] units along the c crystallographic axis. The latter\nunit allows a large increase in capacity, while the [AB5] unit provides good\ncycling stability. Consequently, the AB3.8 composition (i.e. A5B19 with three\n[AB5] for one [A2B4]) is expected to exhibit better cycling stability than the\nAB3.5 (i.e. A2B7 with two [AB5] for one [A2B4]). Furthermore, substitution of\nrare earth by light magnesium improves both the capacity and cycling stability.\nIn this paper, we compare the hydrogenation and corrosion properties of two\nbinary compounds SmNi$_{3.5}$ and SmNi$_{3.8}$ and two pseudo-binary ones\n(Sm,Mg)Ni$_{3.5}$ and (Sm,Mg)Ni$_{3.8}$. A better solid-gas cycling stability\nis highlighted for the binary SmNi$_{3.8}$. The pseudo-binary compounds also\nexhibit higher cycling stability than the binary ones. Furthermore, their\nresistance to corrosion was investigated."
    },
    {
        "anchor": "Multi-Layered Plasmonic Covers for Comb-Like Scattering Response and\n  Optical Tagging: We discuss the potential of multilayered plasmonic particles to tailor the\noptical scattering response. The interplay of plasmons localized in thin\nstacked shells realizes peculiar degenerate cloaking and resonant states\noccurring at arbitrarily close frequencies. These concepts are applied to\nrealize ultrasharp comb-like scattering responses and synthesize staggered,\nideally strong super-scattering states closely coupled to invisible states. We\ndemonstrate robustness to material losses and to variations in the background\nmedium, properties that make these structures ideal for optical tagging.",
        "positive": "Pulsed thermal deposition of binary and ternary transition metal\n  dichalcogenide monolayers and heterostructures: Application of transition metal dichalcogenides (TMDC) in photonic,\noptoelectronic or valleytronic devices requires the growth of continuous\nmonolayers, heterostructures and alloys of different materials in a single\nprocess. We present a facile pulsed thermal deposition method which provides\nprecise control over layer thickness and stoichiometry of two-dimensional\nsystems. The versatility of the method is demonstrated on ternary monolayers of\nMo$_{1-x}$W$_{x}$S$_{2}$ and on heterostructures combining metallic TaS$_{2}$\nand semiconducting MoS$_{2}$ layers. The fabricated ternary monolayers cover\nthe entire composition range of $x$ = 0...1 without phase separation. Band gap\nengineering and control over the spin-orbit coupling strength is demonstrated\nby absorption and photoluminescence spectroscopy. Vertical heterostructures are\ngrown without intermixing. The formation of clean and atomically abrupt\ninterfaces is evidenced by high-resolution transmission electron microscopy.\nSince both the metal components as well as the chalcogenides are thermally\nevaporated complex alloys and heterostructures can thus be prepared."
    },
    {
        "anchor": "Work Function of Bismuth Telluride: First-Principles Approach: First-principles approach is demonstrated to calculate the work function of\nBi2Te3. The reference potential and the vacuum energy levels are extracted from\nthe Bi2Te3 (0001) surface structure using the reference potential method based\non the density functional theory. The one-shot GOWO many-body perturbation\ntheory is used to place the bulk band edge energies with respect to the\nreference level and the vacuum energy. At last, the work function of 5.301 -\n5.131 eV is predicted for Bi2Te3 (0001) surface and compared to various\nelements.",
        "positive": "Evolution of the free volume between rough surfaces in contact: The free volume comprised between rough surfaces in contact governs the\nfluid/gas transport properties across networks of cracks and the\nleakage/percolation phenomena in seals. In this study, a fundamental insight\ninto the evolution of the free volume depending on the mean plane separation,\non the real contact area and on the applied pressure is gained in reference to\nfractal surfaces whose contact response is solved using the boundary element\nmethod. Particular attention is paid to the effect of the surface fractal\ndimension and of the surface resolution on the predicted results. The free\nvolume domains corresponding to different threshold levels are found to display\nfractal spatial distributions whose bounds to their fractal dimensions are\ntheoretically derived. A synthetic formula based on the probability\ndistribution function of the free volumes is proposed to synthetically\ninterpret the numerically observed trends."
    },
    {
        "anchor": "Enhanced and Tunable Spin-Orbit Coupling in Tetragonally Strained\n  Fe-Co-B Films: We have synthesized 20 nm thick films of tetragonally strained interstitial\nFe-Co-B alloys epitaxially grown on Au55Cu45 buffer layer. The strained axis is\nperpendicular to the film plane and the corresponding lattice constant c is\nenlarged with respect to the in-plane lattice parameter a. By adding the\ninterstitial boron with different concentrations 0, 4, and 10 at.% we were able\nto stabilize the tetragonal strain in 20 nm Fe-Co films with different c/a\nratios of 1.013, 1.034 and 1.02, respectively. Using ferromagnetic resonance\n(FMR) and x-ray magnetic circular dichroism (XMCD) we found that the orbital\nmagnetic moment increases with increasing the c/a ratio, pointing towards the\nenhancement of spin-orbit coupling (SOC) at larger strain. Our results show\nthat careful doping of ferromagnetic films allows to control the SOC by\nstabilizing anisotropic strain states. These findings are applicable in\nmaterial design for spintronics applications. We also discuss the influence of\nB doping on the Fe-Co film microstructure, its magnetic properties and magnetic\nrelaxation.",
        "positive": "Metal halide perovskite toxicity effects on plants are caused by iodide\n  ions: Highly-efficient solar cells containing lead halide perovskites are expected\nto revolutionize sustainable energy production in the coming years. Combining\nthese next-generation solar panels with agriculture, can optimize land-use, but\nbrings new risks in case of leakage into the soil. Perovskites are generally\nassumed to be toxic because of the lead (Pb), but experimental evidence to\nsupport this prediction is scarce. We used Arabidopsis thaliana to test the\ntoxicity of the lead-based perovskite MAPbI3 (MA = CH3NH3) and several of its\nprecursors in plants. Our results show that MAPbI3 severely hampers plant\ngrowth at concentrations above 5 microM. Surprisingly, we find that the\nprecursors MAI is equally toxic, while lead-based precursors without iodide are\nonly toxic above 500 microM. These observations reveal that perovskite toxicity\nat low concentrations is caused by iodide ions specifically, and contrast the\nwidespread idea that lead is the most harmful component. We calculate that\niodide toxicity thresholds are likely to reach in the soil upon perovskite\nleakage, but much less so for lead toxicity thresholds. Hence, this work\nstresses the importance to further understand and predict harmful effects of\niodide-containing perovskites in the environment."
    },
    {
        "anchor": "A universal model for the formation energy prediction of inorganic\n  compounds: Harnessing the recent advance in data science and materials science, it is\nfeasible today to build predictive models for materials properties. In this\nstudy, we employ the data of high-throughput quantum mechanics calculations\nbased on 170,714 inorganic crystalline compounds to train a machine learning\nmodel for formation energy prediction. Different from the previous work, our\nmodel reaches a fairly good predictive ability (R2=0.982 and MAE=0.07 eVatom-1,\nDenseNet model) and meanwhile can be universally applied to the large phase\nspace of inorganic materials. The improvement comes from several effective\nstructure-dependent descriptors that are proposed to take the information of\nelectronegativity and structure into account. This model can provide a useful\ntool to search for new materials in a vast phase space in a fast and\ncost-effective manner.",
        "positive": "Finite temperature dielectric properties of KTaO$_3$ from first\n  principles and machine learning: Phonon spectra, Barrett law, strain\n  engineering and electrostriction: Despite important breakthroughs in the last decade, the calculation of\ntemperature dependent properties of solids still remains a challenging task,\nespecially in the vicinity of structural phase transitions. We show that the\ncombination of machine-learning interatomic potentials with quantum\nself-consistent ab initio lattice dynamics allows to calculate efficiently the\ntemperature dependence of dielectric properties of the quantum paraelectric\nperovskite KTaO$_3$, with a precision beyond what could be reasonably achieved\nusing plain density functional theory. We first follow the strong anharmonic\nsoftening of the polar mode in this incipient ferroelectric material, and the\nresulting divergence of the dielectric constant that eventually saturates due\nto the interplay between temperature and quantum fluctuations. Further, we\npredict the stability range of the quantum paraelectric state under the\napplication of epitaxial strain at 0 K and 300 K. Finally, we calculate the\ntemperature dependence of electrostrictive tensors for this material and show\nthat giant electrostriction in KTaO$_3$ is to be expected also at room\ntemperature under the condition of strain engineering."
    },
    {
        "anchor": "Ab-initio investigation of the physical properties of BaAgAs Dirac\n  semimetal and its possible thermo-mechanical and optoelectronic applications: BaAgAs is a ternary Dirac semimetal which can be tuned across a number of\ntopological orders. In this study we have investigated the bulk physical\nproperties of BaAgAs using density functional theory based computations. Most\nof the results presented in this work are novel. The optimized structural\nparameters are in good agreement with previous results. The elastic constants\nindicate that BaAgAs is mechanically stable and brittle in nature. The compound\nis moderately hard and possesses fair degree of machinability. There is\nsignificant mechanical/elastic anisotropy in BaAgAs. The Debye temperature of\nthe compound is medium and the phonon thermal conductivity and melting\ntemperature are moderate as well. The bonding character is mixed with notable\ncovalent contribution. The electronic band structure calculations reveal clear\nsemimetallic behavior with a Dirac node at the Fermi level. BaAgAs has a small\nellipsoidal Fermi surface centered at the G-point of the Brillouin zone. The\nphonon dispersion curves show dynamical stability. There is a clear phonon band\ngap between the acoustic and the optical branches. The energy dependent optical\nconstants conform to the band structure calculations. The compound is an\nefficient absorber of the ultraviolet light and has potential to be used as an\nanti-reflection coating. Optical anisotropy of BaAgAs is moderate. The computed\nrepulsive Coulomb pseudopotential is low indicating that the electronic\ncorrelations in this compound are not strong.",
        "positive": "Influence of the inhomogeneous field at the tip on quantitative\n  piezoresponse force microscopy: Ferroelectric domain imaging with piezoresponse force microscopy (PFM) relies\non the converse piezoelectric effect: a voltage applied to the sample leads to\nmechanical deformations. In case of PFM one electrode is realized by the tip,\ntherefore generating a strongly inhomogeneous electric field distribution\ninside the sample which reaches values up to $10^8 $V/m directly underneath the\napex of the tip. Although often assumed, this high electric field does not lead\nto an enhancement of the piezoelectric deformation of the sample. On the\ncontrary, internal clamping of the material reduces the observed deformation\ncompared to the theoretically expected value which depends only on the voltage\nthus being independent of the exact field distribution."
    },
    {
        "anchor": "Spin-Orbit Coupling in an f-electron Tight-Binding Model: We extend a tight-binding method to include the effects of spin-orbit\ncoupling, and apply it to the study of the electronic properties of the\nactinide elements Th, U, and Pu. These tight-binding parameters are determined\nfor the fcc crystal structure using the equivalent equilibrium volumes. In\nterms of the single particle energies and the electronic density of states, the\noverall quality of the tight-binding representation is excellent and of the\nsame quality as without spin-orbit coupling. The values of the optimized\ntight-binding spin-orbit coupling parameters are comparable to those determined\nfrom purely atomic calculations.",
        "positive": "Two-temperature continuum thermomechanics of deforming amorphous solids: There is an ever-growing need for predictive models for the\nelasto-viscoplastic deformation of solids. Our goal in this paper is to\nincorporate recently developed out-of-equilibrium statistical concepts into a\nthermodynamically consistent, finite-deformation, continuum framework for\ndeforming amorphous solids. The basic premise is that the configurational\ndegrees of freedom of the material --- the part of the internal energy/entropy\nthat corresponds to mechanically stable microscopic configurations --- are\ncharacterized by a configurational temperature that might differ from that of\nthe vibrational degrees of freedom, which equilibrate rapidly with an external\nheat bath. This results in an approximate internal energy decomposition into\nweakly interacting configurational and vibrational subsystems, which exchange\nenergy following a Fourier-like law, leading to a thermomechanical framework\npermitting two well-defined temperatures. In this framework, internal variables\nthat carry information about the state of the material equilibrate with the\nconfigurational subsystem, are explicitly associated with energy and entropy of\ntheir own, and couple to a viscoplastic flow rule. The coefficients that\ndetermine the rate of flow of entropy and heat between different internal\nsystems are proposed to explicitly depend on the rate of irreversible\ndeformation. As an application of this framework, we discuss two constitutive\nmodels for the response of glassy materials, a simple phenomenological model\nand a model related to the concept of Shear-Transformation-Zones as the basis\nfor internal variables. The models account for several salient features of\nglassy deformation phenomenology. Directions for future investigation are\nbriefly discussed."
    },
    {
        "anchor": "Mitigating E-beam-induced Hydrocarbon Deposition on Graphene for\n  Atomic-Scale Scanning Transmission Electron Microscopy Studies: CVD grown graphene used in (scanning) transmission electron microscopy\n((S)TEM) studies must undergo a careful transfer of the one-atom-thick membrane\nfrom the growth surface (typically a Cu foil) to the TEM grid. During this\ntransfer process, the graphene invariably becomes contaminated with foreign\nmaterial. This contamination proves to be very problematic in the (S)TEM\nbecause often >95% of the graphene is obscured and imaging of the pristine\nareas results in e-beam-induced hydrocarbon deposition which further acts to\nobscure the desired imaging area. In this article, we examine two cleaning\ntechniques for CVD grown graphene that mitigate both aspects of the\ncontamination problem: visible contamination covering the graphene, and\ninvisible contamination that deposits onto the graphene under e-beam\nirradiation. The visible contamination may be removed quickly by a rapid\nthermal annealing to 1200 C in situ and the invisible e-beam-deposited\ncontamination may be removed through an Ar/O2 annealing procedure prior to\nimaging in the (S)TEM.",
        "positive": "Optoelectronic properties of the CuI, AgI and Janus Cu2BrI, and Ag2BrI\n  monolayers by many-body perturbation theory: In an outstanding experimental advance in the field of two-dimensional\nnanomaterials, cuprous iodide (CuI) and silver iodide (AgI) monolayers have\nbeen grown via a novel graphene encapsulation synthesis approach\n[Adv.Mater.2022, 34, 2106922]. Inspired by this accomplishment, we conduct\nfirst-principles calculations to investigate the elastic, phononic thermal\ntransport, electronic, and optical properties of the native CuI and AgI and\nJanus Cu2BrI and Ag2BrI monolayers. Electronic and excitonic optical properties\nare elaborately studied using the many-body perturbation theory on the basis of\nGW approximation. Our results indicate that these novel systems are stable but\nwith soft elastic modulus and ultralow lattice thermal conductivity. It is also\nshown that the studied monolayers are wide-gap semiconductors with exciton\nbinding energies close to 1 eV. The effects of mechanical straining and\nelectric field on the resulting electronic and optical properties are also\nanalyzed. The presented first-principles results provide a deep understanding\nof the stability, phononic transport, and tunable optoelectronic properties of\nthe native CuI and AgI and Janus Cu2BrI and Ag2BrI monolayers, which can serve\nas a guide for the oncoming studies."
    },
    {
        "anchor": "Thermodynamic theory of crystal plasticity: formulation and application\n  to polycrystal fcc copper: We present a thermodynamic description of crystal plasticity. Our formulation\nis based on the Langer-Bouchbinder-Lookman thermodynamic dislocation theory\n(TDT), which asserts the fundamental importance of an effective temperature\nthat describes the state of configurational disorder and therefore the\ndislocation density of the crystalline material. We extend the TDT description\nfrom isotropic plasticity to crystal plasticity with many slip systems.\nFinite-element simulations show favourable comparison with experiments on\npolycrystal fcc copper under uniaxial compression, tension, and simple shear.\nThe thermodynamic theory of crystal plasticity thus provides a\nthermodynamically consistent and physically rigorous description of dislocation\nmotion in crystals. We also discuss new insights about the interaction of\ndislocations belonging to different slip systems.",
        "positive": "Local structure and its implications for the relaxor ferroelectric\n  Cd$_2$Nb$_2$O$_7$: The relaxor ferroelectric transition in Cd$_2$Nb$_2$O$_7$ is thought to be\ndescribed by the unusual condensation of two $\\Gamma$-centered phonon modes,\n$\\Gamma_4^-$ and $\\Gamma_5^-$. However, their respective roles have proven to\nbe ambiguous, with disagreement between $\\textit{ab initio}$ studies, which\nfavor $\\Gamma_4^-$ as the primary mode, and global crystal refinements, which\npoint to $\\Gamma_5^-$ instead. Here, we resolve this issue by demonstrating\nfrom x-ray pair distribution function measurements that locally, $\\Gamma_4^-$\ndominates, but globally, $\\Gamma_5^-$ dominates. This behavior is consistent\nwith the near degeneracy of the energy surfaces associated with these two\ndistortion modes found in our own $\\textit{ab initio}$ simulations. Our\nfirst-principles calculations also show that these energy surfaces are almost\nisotropic, providing an explanation for the numerous structural transitions\nfound in Cd$_2$Nb$_2$O$_7$, as well as its relaxor behavior. Our results point\nto several candidate descriptions of the local structure, some of which\ndemonstrate two-in/two-out behavior for Nb displacements within a given Nb\ntetrahedron. Although this suggests the possibility of a charge analog of spin\nice in Cd$_2$Nb$_2$O$_7$, our results are more consistent with a\nHeisenberg-like description for dipolar fluctuations rather than an Ising one.\nWe hope this encourages future experimental investigations of the Nb and Cd\ndipolar fluctuations, along with their associated mode dynamics."
    },
    {
        "anchor": "Quantized Friction across Ionic Liquid Thin Films: Ionic liquids, salts in the liquid state under ambient conditions, are of\ngreat interest as precision lubricants. Ionic liquids form layered structures\nat surfaces, yet it is not clear how this nano-structure relates to their\nlubrication properties. We measured the friction force between atomically\nsmooth solid surfaces across ionic liquid films of controlled thickness in\nterms of the number of ion layers. Multiple friction-load regimes emerge, each\ncorresponding to a different number of ion layers in the film. In contrast to\nmolecular liquids, the friction coefficients differ for each layer due to their\nvarying composition.",
        "positive": "Motion of Contact Line of a Crystal Over the Edge of Solid Mask in\n  Epitaxial Lateral Overgrowth: Mathematical model that allows for direct tracking of the homoepitaxial\ncrystal growth out of the window etched in the solid, pre-deposited layer on\nthe substrate is described. The growth is governed by the normal (to the\ncrystal-vapor interface) flux from the vapor phase and by the interface\ndiffusion. The model accounts for possibly inhomogeneous energy of the mask\nsurface and for strong anisotropies of crystal-vapor interfacial energy and\nkinetic mobility. Results demonstrate that the motion of the crystal-mask\ncontact line slows down abruptly as radius of curvature of the mask edge\napproaches zero. Numerical procedure is suggested to overcome difficulties\nassociated with ill-posedness of the evolution problem for the interface with\nstrong energy anisotropy.\n  Keywords: Thin films, epitaxy, MOCVD, surface diffusion, interface dynamics,\ncontact lines, rough surfaces, wetting, regularization of ill-posed evolution\nproblems."
    },
    {
        "anchor": "Ab-initio chemical potentials of solid and liquid solutions and the\n  chemistry of the Earth's core: A general set of methods is presented for calculating chemical potentials in\nsolid and liquid mixtures using {\\em ab initio} techniques based on density\nfunctional theory (DFT). The methods are designed to give an {\\em ab initio}\napproach to treating chemical equilibrium between coexisting solid and liquid\nsolutions, and particularly the partitioning ratio of solutes between such\nsolutions. For the liquid phase, the methods are based on the general technique\nof thermodynamic integration, applied to calculate the change of free energy\nassociated with the continuous interconversion of solvent and solute atoms, the\nrequired thermal averages being computed by DFT molecular dynamics simulation.\nFor the solid phase, free energies and hence chemical potentials are obtained\nusing DFT calculation of vibrational frequencies of systems containing\nsubstitutional solute atoms, with anharmonic contributions calculated, where\nneeded, by thermodynamic integration. The practical use of the methods is\nillustrated by applying them to study chemical equilibrium between the outer\nliquid and inner solid parts of the Earth's core, modelled as solutions of S,\nSi and O in Fe. The calculations place strong constraints on the chemical\ncomposition of the core, and allow an estimate of the temperature at the\ninner-core/outer-core boundary.",
        "positive": "Thermal stimulated current response in cupric oxide single crystal thin\n  films over a wide temperature range: Cupric oxide single crystal thin films were grown by plasma-assisted\nmolecular beam epitaxy. X-ray diffraction, Raman spectrum and in situ\nreflection high-energy electron diffraction show that the thin films are 2x2\nreconstructed with an in-plane compression and out-of-plane stretching. Thermal\nstimulated current measurement indicates that the electric polarization\nresponse presents in the special 2D cupric oxide single crystal thin film over\na wide temperature range from 130 K to near-room temperature. We infer that the\nabnormal electric response involves the changing of phase transition\ntemperature induced by structure distortion, the spin frustration and magnetic\nfluctuation effect of short-range magnetic order, or the combined action of\nboth two factors mentioned above. This work suggests a promising clue for\nfinding new room temperature single phase multiferroics or tuning phase\ntransition temperature."
    },
    {
        "anchor": "Antiferromagnetic domain wall motion driven by polarized spin waves: The control of magnetic domain walls is essential for the magnetic-based\nmemory and logic applications. As an elementary excitation of magnetic order,\nspin wave is capable of moving magnetic domain walls just as the conducting\nelectric current. Ferromagnetic spin waves can only be right-circularly\npolarized. In contrast, antiferromagnetic spin waves have full polarization\ndegree of freedom, including both left- and right-circular polarizations, as\nwell as all possible linear or elliptical ones. Here we demonstrate that, due\nto the Dzyaloshinskii-Moriya interaction, the spin wave driven domain wall\nmotion in antiferromagnets strongly depends on the linear polarization\ndirection of the injected spin waves. Steering domain wall motion by simply\ntuning the polarization of spin waves offers new designing principles for\ndomain-wall based information processing devices.",
        "positive": "Damage Preserving Transformation for Materials with Microstructure: The failure of heterogeneous materials with microstructures is a complex\nprocess of damage nucleation, growth and localisation. This process spans\nmultiple length scales and is challenging to simulate numerically due to its\nhigh computational cost. One option is to use domain decomposed multi-scale\nmethods with dynamical refinement. If needed, these methods refine coarse\nregions into a fine-scale representation to explicitly model the damage in the\nmicrostructure. However, damage evolution is commonly restricted to fine-scale\nregions only. Thus, they are unable to capture the full complexity and breath\nof the degradation process in the material. In this contribution, a generic\nprocedure that allows to account for damage in all representations is proposed.\nThe approach combines a specially designed orthotropic damage law, with a\nscheme to generate pre-damaged fine-scale microstructures. Results indicate\nthat the damage approximation for the coarse representation works well.\nFurthermore, the generated fine-scale damage patterns are overall consistent\nwith explicitly simulated damage patterns. Minor discrepancies occur in the\ngeneration but subsequently vanish when explicit damage evolution continuous;\nfor instance under increased load. The presented approach provides a\nmethodological basis for adaptive multi-scale simulation schemes with\nconsistent damage evolution."
    },
    {
        "anchor": "3d-electron induced magnetic phase transition in half-metallic\n  semi-Heusler alloys: We study the effect of the non-magnetic 3\\textit{d} atoms on the magnetic\nproperties of the half-metallic (HM) semi-Heusler alloys Co$_{1-x}$Cu$_{x}$MnSb\nand Ni$_{1-x}$Cu$_{x}$MnSb ($0 \\leq x \\leq 1$) using first-principles\ncalculations. We determine the magnetic phase diagram of both systems at zero\ntemperature and obtain a phase transition from a ferromagnetic to an\nantiferromagnetic state. For low Cu concentrations the ferromagnetic RKKY-like\nexchange mechanism is dominating, while the antiferromagnetic superexchange\ncoupling becomes important for larger Cu content leading to the observed\nmagnetic phase transition. A strong dependence of the magnetism in both systems\non the position of the Fermi level within the HM gap is obtained. Obtained\nresults are in good agreement with the available experimental data.",
        "positive": "Polaronic-Quasiparticle Picture for Generation Dynamics of Coherent\n  Phonons in Semiconductors: Transient and Non-Linear Fano Resonance: We examine generation dynamics of coherent phonons (CPs) in both of polar and\nnon-polar semiconductors -- such as GaAs and Si -- based on a\npolaronic-quasiparticle (PQ) model. In the model concerned, the PQ operator is\ncomposed of two kinds of operators. One is a quasiboson operator -- defined as\na linear combination of a set of pairs of electron operators -- and the other\nis a longitudinal optical (LO) phonon operator. The problem of transient and\nnon-linear Fano resonance (FR) is tackled in particular; the vestige of this\nquantum interference effect was observed exclusively in lightly $n$-doped Si\nimmediately after carriers were excited by an ultrashort pulse-laser [M. Hase\net. al., Nature 426, 51 (2003)], though not observed yet in GaAs. It is shown\nthat the phonon energy state is embedded in a continuum state formed by a set\nof adiabatic eigenstates of the quasiboson. This result implies the possibility\nof manifestation of the transient FR in the present optically-non-linear\nsystem."
    },
    {
        "anchor": "Grain boundary complexions and the strength of nanocrystalline metals:\n  Dislocation emission and propagation: Grain boundary complexions have been observed to affect the mechanical\nbehavior of nanocrystalline metals, improving both strength and ductility.\nWhile an explanation for the improved ductility exists, the observed effect on\nstrength remains unexplained. In this work, we use atomistic simulations to\nexplore the influence of ordered and disordered complexions on two deformation\nmechanisms which are essential for nanocrystalline plasticity, namely\ndislocation emission and propagation. Both ordered and disordered grain\nboundary complexions in Cu-Zr are characterized by excess free volume and\npromote dislocation emission by reducing the critical emission stress.\nAlternatively, these complexions are characterized by strong dislocation\npinning regions that increase the flow stress required for dislocation\npropagation. Such pinning regions are caused by ledges and solute atoms at the\ngrain-complexion interfaces and may be dependent on the complexion state as\nwell as the atomic size mismatch between the matrix and solute elements. The\ntrends observed in our simulations of dislocation propagation align with the\navailable experimental data, suggesting that dislocation propagation is the\nrate-limiting mechanism behind plasticity in nanocrystalline Cu-Zr alloys.",
        "positive": "Tuning electronic properties and contact type in van der Waals\n  heterostructures of bilayer SnS and graphene: Using first-principles calculations, we study the structural and electronic\nproperties of the bilayer SnS/graphene, bilayer SnS/bilayer graphene\n(AA-stacked), bilayer SnS/bilayer graphene (AB-stacked) and monolayer\nSnS/graphene/monolayer SnS van der Waals (vdW) heterostructures. Electronic\nproperties of all components of the vdW heterostructures are well preserved,\nwhich reflects the weakness of the vdW interaction. In the cases of bilayer\nSnS/graphene and bilayer SnS/bilayer graphene (AA-stacked), an Ohmic contact is\nformed which can be turned first into p-type and then into n-type Schottky\ncontacts via application of an external electric field. Calculations show that\nan Ohmic contact is also formed at the interface of bilayer SnS/bilayer\ngraphene (AB-stacked) heterostructure, but interestingly, by applying the\nperpendicular electric field a transition from semimetal/semiconductor contact\nto semiconductor/semiconductor one occurs which can enhance its optical\nproperties. Alternatively, in the monolayer SnS/graphene/monolayer SnS vdW\nheterosructure, a p-type Schottky contact is established that changes into\nOhmic contact under an applied electric field. Our results clearly indicate\nthat the electronic properties of the vdW heterostructures can be tuned\nefficiently by external electric field, which is important in designing of new\nnanoelectronic devices."
    },
    {
        "anchor": "On the Active Components in Crystalline Li-Nb-O and Li-Ta-O Coatings\n  from First Principles: Layered-oxide $\\mathrm{LiNi_xMn_yCo_{1-x-y}O_2}$ (NMC) positive electrodes\nwith high Nickel content, deliver high voltages and energy densities. However,\na high nickel content, e.g., $x$ = 0.8 (NMC 811), can lead to high surface\nreactivity, which can trigger thermal runaway and gas generation. While claimed\nsafer, all-solid-state batteries still suffer from high interfacial resistance.\nHere, we investigate niobate and tantalate coating materials, which can\nmitigate the interfacial reactivities in Li-ion and all-solid-state batteries.\nFirst-principles calculations reveal the multiphasic nature of Li-Nb-O and\nLi-Ta-O coatings, containing mixtures of $\\mathrm{LiNbO_3}$ and\n$\\mathrm{Li_3NbO_4}$, or of $\\mathrm{LiTaO_3}$ and $\\mathrm{Li_3TaO_4}$. The\nconcurrence of several phases in Li-Nb-O or Li-Ta-O modulates the type of\nstable native defects in these coatings. Li-Nb-O and Li-Ta-O coating materials\ncan form favorably lithium vacancies $\\mathrm{Vac^{'}_{Li}}$ and antisite\ndefects $\\mathrm{Nb^{\\bullet \\bullet \\bullet \\bullet}_{Li}}$\n($\\mathrm{Ta^{\\bullet \\bullet \\bullet \\bullet}_{Li}}$) combined into\ncharge-neutral defect complexes. Even in defective crystalline\n$\\mathrm{LiNbO_3}$ (or $\\mathrm{LiTaO_3}$), we reveal poor Li-ion conduction\nproperties. In contrast, $\\mathrm{Li_3NbO_4}$ and $\\mathrm{Li_3TaO_4}$ that are\nintroduced by high-temperature calcinations can provide adequate Li-ion\ntransport in these coatings. Our in-depth investigation of the\nstructure-property relationships in the important Li-Nb-O and Li-Ta-O coating\nmaterials helps to develop more suitable calcination protocols to maximize the\nfunctional properties of these niobates and tantalates.",
        "positive": "Density-functional study of plutonium monoxide monohydride: The structural, electronic, mechanical, optical, thermodynamic properties of\nplutonium monoxide monohydride (PuOH) are studied by density-functional\ncalculations within the framework of LDA/GGA and LDA/GGA+U.From the total\nenergy calculation, the lowest-energy crystal structure of PuOH is predicted to\nhave space group F-43m (No. 216). Within the LDA+U framework, the calculated\nlattice parameter of F-43m-PuOH is in good agreement with the experimental\nvalue and the corresponding ground state is predicted to be an\nantiferromagnetic charge-transfer insulator. Furthermore, we investigate the\nbonding character of PuOH by analyzing the electron structure and find that\nthere are a stronger Pu-O bond and a weaker Pu-H bond.The mechanical properties\nincluding the elastic constants, elastic moduli and Debye's temperature, and\nthe optical properties including the reflectivity and absorption coefficient\nare also calculated. We then compute the phonon spectrum which verified the\ndynamical stability of F-43m-PuOH. Some thermodynamic quantities such as the\nspecific heat are evaluated. Finally we calculate the formation energy of PuOH,\nand the reaction energies for the oxidation of PuOH and PuOH-coated Pu, which\nare in reasonable agreement with the experimental values."
    },
    {
        "anchor": "A Relativistic DFT Study of Water Adsorption on delta-Plutonium (111)\n  Surface: Scalar-relativistic DFT-GGA has been used to study adsorption of water in\nmolecular and dissociative configurations on delta-Plutonium (111) surface. In\nmolecular state, water is physisorbed in an almost flat-lying orientation at a\none-fold coordinated on-top site. The interaction of the water 1b1 orbital and\nthe Pu-6d orbital provides the stability of water on the surface, implying that\nthe Pu-5f electrons remain chemically inert. The co-adsorption cases of\npartially dissociated and fully dissociated products at the three-fold hollow\nsites yield chemisorption, coupled with rumpling of the surface layer and\ndelocalization of the Pu-5f electrons and formation of strong ionic bonds.",
        "positive": "Structural and magnetic properties of Fe/ZnSe(001) interfaces: We have performed first principles electronic structure calculations to\ninvestigate the structural and magnetic properties of Fe/ZnSe(001) interfaces.\nCalculations involving full geometry optimizations have been carried out for a\nbroad range of thickness of Fe layers(0.5 monolayer to 10 monolayers) on top of\na ZnSe(001) substrate. Both Zn and Se terminated interfaces have been explored.\nTotal energy calculations show that Se segregates at the surface which is in\nagreement with recent experiments.\n  For both Zn and Se terminations, the interface Fe magnetic moments are higher\nthan the bulk bcc Fe moment.\n  We have also investigated the effect of adding Fe atoms on top of a\nreconstructed ZnSe surface to explore the role of reconstruction of\nsemiconductor surfaces in determining properties of metal-semiconductor\ninterfaces. Fe breaks the Se dimer bond formed for a Se-rich (2x1)\nreconstructed surface. Finally, we looked at the reverse growth i.e. growth of\nZn and Se atoms on a bcc Fe(001) substrate to investigate the properties of the\nsecond interface of a magnetotunnel junction. The results are in good agreement\nwith the theoretical and experimental results, wherever available."
    },
    {
        "anchor": "Exchange interaction and its tuning in magnetic binary chalcogenides: Using a first-principles Green's function approach we study magnetic\nproperties of the magnetic binary chalcogenides Bi2Te3, Bi2Se3, and Sb2Te3. The\nmagnetic coupling between transition-metal impurities is long-range, extends\nbeyond a quintuple layer, and decreases with increasing number of d electrons\nper 3d atom. We find two main mechanisms for the magnetic interaction in these\nmaterials: the indirect exchange interaction mediated by free carriers and the\nindirect interaction between magnetic moments via chalcogen atoms. The\ncalculated Curie temperatures of these systems are in good agreement with\navailable experimental data. Our results provide deep insight into magnetic\ninteractions in magnetic binary chalcogenides and open a way to design new\nmaterials for promising applications.",
        "positive": "Band alignment of monolayer CaP$_3$, CaAs$_3$, BaAs$_3$ and the role of\n  $p$-$d$ orbital interactions in the formation of conduction band minima: Recently, a number of new two-dimensional (2D) materials based on puckered\nphosphorene and arsenene have been predicted with moderate band gaps, good\nabsorption properties and carrier mobilities superior to transition metal\ndichalcogenides. For heterojunction applications, it is important to know the\nrelative band alignment of these new 2D materials. We report the band alignment\nof puckered CaP$_3$, CaAs$_3$ and BaAs$_3$ monolayers at the quasiparticle\nlevel of theory (G$_0$W$_0$), calculating band offsets for isolated monolayers\naccording to the electron affinity rule. Our calculations suggest that\nmonolayer CaP$_3$, CaAs$_3$ and BaAs$_3$ all form type-II (staggered)\nheterojunctions. Their quasiparticle gaps are 2.1 (direct), 1.8 (direct) and\n1.5 eV (indirect), respectively. We also examine trends in the electronic\nstructure in the light of chemical bonding analysis. We show that the indirect\nband gap in monolayer BaAs$_3$ is caused by relatively strong As $3p$ - Ba $5d$\nbonding interactions that stabilize the conduction band away from the $\\Gamma$\npoint between $\\Gamma$ and $S$."
    },
    {
        "anchor": "Hybrid nano-domain structures of organic-inorganic perovskites from\n  molecule-cage coupling effects: In hybrid perovskites, the organic molecules and inorganic frameworks exhibit\ndistinct static and dynamic characteristics. Their coupling will lead to\nunprecedented phenomena, which have attracted wide research interests. In this\npaper, we employed Deep Potential molecular dynamics (DPMD), a large-scale MD\nsimulation scheme with DFT accuracy, to study $\\mathrm{FA/MAPbI_3}$ hybrid\nperovskites. A spontaneous hybrid nano-domain behavior, namely multiple\nmolecular rotation nano-domains embedded into a single $\\mathrm{[PbI_6]^{4-}}$\noctahedra rotation domain, was firstly discovered at low temperatures. The\nbehavior originates from the interplay between the long range order of\nmolecular rotation and local lattice deformation, and clarifies the puzzling\ndiffraction patterns of $\\mathrm{FAPbI_3}$ at low temperatures. Our work\nprovides new insights into the structural characteristics and stability of\nhybrid perovskite, as well as new ideas for the structural characterization of\norganic-inorganic coupled systems.",
        "positive": "Exciton spectroscopy and diffusion in MoSe2-WSe2 lateral\n  heterostructures encapsulated in hexagonal boron nitride: Chemical vapor deposition (CVD) allows lateral edge epitaxy of transition\nmetal dichalcogenide heterostructures with potential applications in\noptoelectronics. Critical for carrier and exciton transport is the quality of\nthe two materials that constitute the monolayer and the nature of the lateral\nheterojunction. Important details of the optical properties were inaccessible\nin as-grown heterostructure samples due to large inhomogeneous broadening of\nthe optical transitions. Here we perform optical spectroscopy at T = 4 K and\nalso at 300 K to access the optical transitions in CVD grown MoSe2-WSe2 lateral\nheterostructures that are transferred from the growth-substrate and are\nencapsulated in hBN. Photoluminescence (PL), reflectance contrast and Raman\nspectroscopy reveal considerably narrowed optical transition linewidth similar\nto high quality exfoliated monolayers. In high-resolution transmission electron\nmicroscopy (HRTEM) we find near-atomically sharp junctions with a typical\nextent of 3nm for the covalently bonded MoSe2-WSe2. In PL imaging experiments\nwe find effective excitonic diffusion length that are longer for WSe2 than for\nMoSe2 at low T=4 K, whereas at 300 K this trend is reversed."
    },
    {
        "anchor": "Covariant derivatives of Berry-type quantities: Application to nonlinear\n  transport: The derivatives of the Berry curvature $\\Omega$ and intrinsic orbital\nmagnetic moment m in momentum space are relevant to various problems, including\nthe nonlinear anomalous Hall effect and magneto-transport within the\nBoltzmann-equation formalism. To investigate these properties using\nfirst-principles methods, we have developed a Wannier interpolation scheme that\nevaluates the ''covariant derivatives'' of the non-Abelian $\\Omega$ and m\nmatrices for a group of bands within a specific energy range of interest.\nUnlike the simple derivative, the covariant derivative does not involve\ncouplings within the groups and preserves the gauge covariance of the $\\Omega$\nand m matrices. In the simulation of nonlinear anomalous Hall conductivity, the\nresulting ''Fermi-sea'' formula for the Berry curvature dipole are more robust\nand converges faster with the density of the integration k-grid than the\n''Fermi-surface'' formula implemented earlier. The developed methodology is\nmade available via the open-source code WannierBerri and we demonstrate the\nefficiency of this method through first-principles calculations on trigonal\nTellurium.",
        "positive": "Origins of anisotropic transport in electrically-switchable\n  antiferromagnet $\\mathrm{Fe_1/3NbS_2}$: Recent experiments on the antiferromagnetic intercalated transition metal\ndichalcogenide $\\mathrm{Fe_{1/3}NbS_2}$ have demonstrated reversible\nresistivity switching by application of orthogonal current pulses below its\nmagnetic ordering temperature, making $\\mathrm{Fe_{1/3}NbS_2}$ promising for\nspintronics applications. Here, we perform density functional theory\ncalculations with Hubbard U corrections of the magnetic order, electronic\nstructure, and transport properties of crystalline $\\mathrm{Fe_{1/3}NbS_2}$,\nclarifying the origin of the different resistance states. The two\nexperimentally proposed antiferromagnetic ground states, corresponding to\nin-plane stripe and zigzag ordering, are computed to be nearly degenerate.\nIn-plane cross sections of the calculated Fermi surfaces are anisotropic for\nboth magnetic orderings, with the degree of anisotropy sensitive to the Hubbard\nU value. The in-plane resistance, computed within the Kubo linear response\nformalism using a constant relaxation time approximation, is also anisotropic,\nsupporting a hypothesis that the current-induced resistance changes are due to\na repopulating of AFM domains. Our calculations indicate that the transport\nanisotropy of $\\mathrm{Fe_{1/3}NbS_2}$ in the zigzag phase is reduced relative\nto stripe, consistent with the relative magnitudes of resistivity changes in\nexperiment. Finally, our calculations reveal the likely directionality of the\ncurrent-domain response, specifically, which domains are energetically\nstabilized for a given current direction."
    },
    {
        "anchor": "Structural and mechanical properties of nitrogen-deficient cubic Cr-Mo-N\n  and Cr-W-N systems: The tendency for nitrogen deficiency in cubic Cr-Mo-N and Cr-W-N solid\nsolutions is predicted by a comprehensive evaluation of the lattice spacing,\nmixing thermodynamics, and elastic properties using first-principles\ncalculations and experimentally confirmed by means of X-ray diffraction. A\nmajor conclusion is that these systems exhibit significant amount of N\nvacancies whose amount scales linearly with the TM content, hence making the\nCr1-xTMxN1-0.5x chemical formula more precise and informative to describe the\nchemical composition of cubic Cr-Mo-N and Cr-W-N solid solutions as compared\nwith the conventionally used Cr1-xTMxN. The cubic Cr1-xMoxN1-0.5x and\nCr1-xWxN1-0.5x solid solutions exhibit large positive mixing enthalpies towards\nisostructural phase decomposition into cubic B1-CrN and {\\gamma}-Mo2N or\n{\\gamma}-W2N, respectively. Their ductility increases with increasing Mo or W\ncontent and both systems exhibit significantly direction-dependent Young's\nmoduli over the entire composition range, even when using the approach to study\ntheir polycrystalline behavior. The excellent agreement between experimentally\nobtained lattice parameters, Mo- and W-dependent nitrogen content, elastic\nproperties and their calculated values for our model descriptions,\nCr1-xMoxN1-0.5x and Cr1-xWxN1-0.5x, allows to understand these complex material\nsystems. Based on our results, we can conclude that their content of nitrogen\nvacancies scales with half of the alloying content Mo or W.",
        "positive": "Preparation of ODA-clay hybrid films by Langmuir-Blodgett technique: Hybrid monolayers of clay minerals (hectorite) and Octadecyamine (ODA) were\nprepared using the Langmuir-Blodgett (LB) technique. Surface pressure-area per\nmolecule isotherm, FTIR and atomic force microscopy were used to confirm and\nanalyze the ODA-hectorite hybrid films. The monolayer thickness is 2 nm and\naverage height, length and width of individual clay platelets ranges between\n1.5 to 2 nm, 500 to 1250 nm and 100 to 115 nm respectively. The surface\ncoverage was more than 80%."
    },
    {
        "anchor": "Structural and electronic properties of highly doped topological\n  insulator Bi2Se3 crystals: We present a study of the structural and electronic properties of highly\ndoped topological insulator Bi2Se3 single crystals synthesized by the Bridgman\nmethod. Lattice structural characterizations by X-ray diffraction, scanning\ntunneling microscopy, and Raman spectroscopy confirmed the high quality of the\nas-grown single crystals. The topological surface states in the electronic band\nstructure were directly re- vealed by angle-resolved photoemission\nspectroscopy. Transport measurements showed that the conduction was dominated\nby the bulk carriers and confirmed a previously observed bulk quantum Hall\neffect in such highly doped Bi2Se3 samples. We briefly discuss several possible\nstrategies of reducing bulk conductance.",
        "positive": "Unimpeded permeation of water through helium-leak-tight graphene-based\n  membranes: Permeation through nanometer pores is important in the design of materials\nfor filtration and separation techniques and because of unusual fundamental\nbehavior arising at the molecular scale. We found that submicron-thick\nmembranes made from graphene oxide can be completely impermeable to liquids,\nvapors and gases, including helium, but allow unimpeded permeation of water\n(H2O permeates through the membranes at least 10^10 times faster than He). We\nattribute these seemingly incompatible observations to a low-friction flow of a\nmonolayer of water through two dimensional capillaries formed by closely spaced\ngraphene sheets. Diffusion of other molecules is blocked by reversible\nnarrowing of the capillaries in low humidity and/or by their clogging with\nwater."
    },
    {
        "anchor": "Instability and Surface Potential Modulation of Self-Patterned\n  (001)SrTiO3 Surfaces: The (001)SrTiO3 crystal surface can be engineered to display a self-organized\npattern of well-separated and nearly pure single-terminated SrO and TiO2\nregions by high temperature annealing in oxidizing atmosphere. By using surface\nsensitive techniques we have obtained evidence of such surface chemical\nself-structuration in as-prepared crystals and unambiguously identified the\nlocal composition. The contact surface potential at regions initially\nconsisting of majority single terminations (SrO and TiO2) is determined to be\nsmaller for SrO than for TiO2, in agreement with theoretical predictions,\nalthough the measured difference below 100 meV is definitely smaller than\ntheoretical predictions for ideally pure single-terminated SrO and TiO2\nsurfaces. These relative values are maintained if samples are annealed in UHV\nup to 200 degrees Celsius. Annealing in UHV at higher temperature (400 degrees\nCelsius) preserves the surface morphology of self-assembled TiO2 and SrO rich\nregions, although a non-negligible chemical intermixing is observed. The most\ndramatic consequence is that the surface potential is reversed. It thus follows\nthat electronic and chemical properties of (001)SrTiO3, widely used in oxide\nthin films growth, can largely vary before growth starts in a manner strongly\ndependent on temperature and pressure conditions.",
        "positive": "Magneto-transport evidence for strong topological insulator phase in\n  ZrTe5: The identification of a non-trivial band topology usually relies on directly\nprobing the protected surface/edge states. But, it is difficult to achieve\nelectronically in narrow-gap topological materials due to the small (meV)\nenergy scales. Here, we demonstrate that band inversion, a crucial ingredient\nof the non-trivial band topology, can serve as an alternative, experimentally\naccessible indicator. We show that an inverted band can lead to a four-fold\nsplitting of the non-zero Landau levels, contrasting the two-fold splitting\n(spin splitting only) in the normal band. We confirm our predictions in\nmagneto-transport experiments on a narrow-gap strong topological insulator,\nzirconium pentatelluride (ZrTe$_5$), with the observation of additional\nsplittings in the quantum oscillations and also an anomalous peak in the\nextreme quantum limit. Our work establishes an effective strategy for\nidentifying the band inversion as well as the associated topological phases for\nfuture topological materials research."
    },
    {
        "anchor": "A Fast Image Simulation Algorithm for Scanning Transmission Electron\n  Microscopy: Image simulation for scanning transmission electron microscopy at atomic\nresolution for samples with realistic dimensions can require very large\ncomputation times using existing simulation algorithms. We present a new\nalgorithm named PRISM that combines features of the two most commonly used\nalgorithms, the Bloch wave and multislice methods. PRISM uses a Fourier\ninterpolation factor $f$ that has typical values of 4-20 for atomic resolution\nsimulations. We show that in many cases PRISM can provide a speedup that scales\nwith $f^4$ compared to multislice simulations, with a negligible loss of\naccuracy. We demonstrate the usefulness of this method with large-scale\nscanning transmission electron microscopy image simulations of a crystalline\nnanoparticle on an amorphous carbon substrate.",
        "positive": "Density-functional study of LixMoS2 intercalates (0<=x<=1): The stability of Lithium intercalated 2H- and 1T allotropes of Molybdenum\ndisulfide (LixMoS2) is studied within a density-functional theory framework as\nfunction of the Li content (x) and the intercalation sites. Octahedral\ncoordination of Li interstitials in the van der Waals gap is found as the most\nfavorite for both allotropes. The critical content of Lithium, required for the\ninitialization of a 2H->1T phase transition is estimated to x ~ 0.4. For\nsmaller Li contents the hexagonal 2H crystal structure is not changed, while\n1T-LixMoS2 compounds adopt a monoclinic lattice. All allotropic forms of\nLixMoS2 - excluding the monoclinic Li1.0MoS2 structure - show metallic-like\ncharacter. The monoclinic Li1.0MoS2 is a semiconductor with a band gap of 1.1\neV. Finally, the influence of Li intercalation on the stability of multiwalled\nMoS2 nanotubes is discussed within a phenomenological model."
    },
    {
        "anchor": "Direct Graphene Growth on Insulator: Fabrication of graphene devices is often hindered by incompatibility between\nthe silicon technology and the methods of graphene growth. Exfoliation from\ngraphite yields excellent films but is good mainly for research. Graphene grown\non metal has a technological potential but requires mechanical transfer. Growth\nby SiC decomposition requires a temperature budget exceeding the technological\nlimits. These issues could be circumvented by growing graphene directly on\ninsulator, implying Van der Waals growth. During growth, the insulator acts as\na support defining the growth plane. In the device, it insulates graphene from\nthe Si substrate. We demonstrate planar growth of graphene on mica surface.\nThis was achieved by molecular beam deposition above 600{\\deg}C. High\nresolution Raman scans illustrate the effect of growth parameters and substrate\ntopography on the film perfection. Ab initio calculations suggest a growth\nmodel. Data analysis highlights the competition between nucleation at surface\nsteps and flat surface. As a proof of concept, we show the evidence of electric\nfield effect in a transistor with a directly grown channel.",
        "positive": "Prediction on Raman Spectra of Intrinsic Two-Dimensional Ga$_2$O$_3$\n  Monolayer: We investigate the vibrational properties and Raman spectra of\ntwo-dimensional Ga$_2$O$_3$ monolayer, using density functional theory. Two\nferroelectric (FE) phases of Ga$_2$O$_3$ monolayer with wurtzite(WZ) and\nzincblende(ZB) structures( FE-WZ and FE-ZB, respectively ) are considered. The\nRaman tensor and angle-dependent Raman intensities of two major Raman peak\n($A^1_1$ and $A^2_1$) in both FE-WZ (497, and 779 cm$^{-1}$) and FE-ZB (481,\nand 772 cm$^{-1}$) Ga$_2$O$_3$ monolayers are calculated for the polarizations\nof scattered light parallel and perpendicular to that of the incident light.\nThe characteristics of angle-dependent Raman intensities are analyzed. The\naveraged non-resonant Raman spectra of minor peaks in FE-WZ($E^1$) and\nFE-BZ($E^1$ and $E^2$) are compared with that of major peaks $A^1_1$ and\n$A^2_1$ . These predictions on Raman spectra of Ga$_2$O$_3$ monolayer may guide\nrational design of two-dimensional optical devices."
    },
    {
        "anchor": "Anisotropic Local Correlations and Dynamics in a Relaxor Ferroelectric: Relaxor ferroelectrics have been a focus of intense attention due to their\nanomalous dielectric characteristics, diffuse phase transitions, and strong\npiezoelectricity. Understanding the structure and dynamics of relaxors has been\none of the long-standing challenges in solid-state physics, with the current\nmodel of polar nanoregions in a non-polar matrix providing only a qualitative\ndescription of the relaxor phase transitions. In this paper, we investigate the\nlocal structure and dynamics in 75%PbMg$_{1/3}$Nb$_{2/3}$O$_3$-25%PbTiO$_3$\n(PMN-PT) using molecular dynamics simulations and the dynamic pair distribution\nfunction technique. We show for the first time that relaxor transitions can be\ndescribed by local order parameters. We find that structurally, the relaxor\nphase is characterized by the presence of highly anisotropic correlations\nbetween the local cation displacements. These correlations resemble the\nhydrogen bond network in water. Our findings contradict the current polar\nnanoregion model; instead, we suggest a new model of a homogeneous random\nnetwork of anisotropically coupled dipoles.",
        "positive": "Nucleation and growth of single wall carbon nanotubes: The nucleation and growth of single wall carbon nanotubes from a\ncarbon-saturated catalytic particle surrounded by a single sheet of graphene is\ndescribed qualitatively by using a very restricted number of elementary\nprocesses, namely Stone-Wales defects and carbon bi-interstitials. Energies of\nthe different configurations are estimated by using a Tersoff energy\nminimization scheme. Such a description is compatible with a broad variety of\nsize or helicity of the tubes. Several mechanisms of growth of the embryos are\nconsidered: one of them is made more favourable when the tubes embryos are\narranged in an hexagonal network in the graphene plane. All the proposed\nmechanisms can be indefinitely repeated for the growth of the nanotubes."
    },
    {
        "anchor": "Equivalent circuit representation of hysteresis in solar cells that\n  considers interface charge accumulation: Potential cause of hysteresis in\n  perovskite solar cells: If charge carriers accumulate in the charge transport layer of a solar cell,\nthen the transient response of the electric field that originates from these\naccumulated charges results in hysteresis in the current-voltage ($J$-$V$)\ncharacteristics. While this mechanism was previously known, a theoretical model\nto explain these $J$-$V$ characteristics has not been considered to date. We\nderived an equivalent circuit from the proposed hysteresis mechanism. By\nsolving the equivalent circuit model, we were able to reproduce some of the\nfeatures of hysteresis in perovskite solar cells.",
        "positive": "Role of Fe substitution on the anomalous magnetocaloric and\n  magnetoresistance behavior in Tb(Ni1-xFex)2 compounds: We report the magnetic, magnetocaloric and magnetoresistance results obtained\nin Tb(Ni1-xFex)2 compounds with x=0, 0.025 and 0.05. Fe substitution leads to\nan increase in the ordering temperature from 36 K for x=0 to 124 K for x=0.05.\nContrary to a single sharp MCE peak seen in TbNi2, the MCE peaks of the Fe\nsubstituted compounds are quite broad. We attribute the anomalous MCE behavior\nto the randomization of the Tb moments brought about by the Fe substitution.\nMagnetic and magnetoresistance results seem to corroborate this proposition.\nThe present study also shows that the anomalous magnetocaloric and\nmagnetoresistance behavior seen in the present compounds is similar to that of\nHo(Ni,Fe)2 compounds."
    },
    {
        "anchor": "Designing of super-elastic freestanding ferroelectric thin films guided\n  by phase-field simulations: Understanding the dynamic behavior of the domain structure is critical to the\ndesign and application of super-elastic freestanding ferroelectric thin films.\nThe phase-field simulation is currently a powerful tool for observing,\nexploring, and revealing domain switching behavior and phase transition in\nferroelectric materials at the mesoscopic scale. The present review summarizes\nthe recent progress of phase-field methods in the theoretical interpretation,\nmechanical response, and domain structure evolution of freestanding\nferroelectric thin films, wrinkled structures, and nano-springs. Furthermore,\nthe strong coupling relationship between strain and ferroelectric polarization\nin super-elastic ferroelectric nanostructures is confirmed and discussed, which\nbrings new design strategies for strain engineering of freestanding\nferroelectric thin film systems. To further promote the innovative development\nand application of the freestanding ferroelectric thin film system, the review\nends with a summary and an outlook on the theoretical model of the freestanding\nferroelectric thin film.",
        "positive": "Elemental Ferroelectric Topological Insulator in $\u03c8$-bismuthene: Ferroelectric quantum spin Hall insulator (FEQSHI) exhibits coexisting\nferroelectricity and time-reversal symmetry protected edge states, holding\nfascinating prospects for inviting both scientific and application advances,\nespecially in two dimensions. However, all of the previously demonstrated\nFEQSHIs consist two or more constituent elements. We herein propose the\n$\\psi$-bismuthene, an uncharted allotrope of bilayer Bi (110), to be the first\nexample of 2D elemental FEQSHI. It is demonstrated that $\\psi$-bismuthene\nharbors measurable ferroelectric polarization and nontrivial band gap with\nmoderate switching barrier, which are highly beneficial for the detection and\nobservation of the ferroelectric topologically insulating states. In addition,\nall-angle auxetic behavior with giant negative Poisson's ratio and\nferroelectric controllable persistent spin helix in $\\psi$-bismuthene are also\ndiscussed. The emergent elemental FEQSHI represents a novel domain for both\nfundamental physics and technological innovation."
    },
    {
        "anchor": "High yield production of graphene by liquid phase exfoliation of\n  graphite: Graphene is at the centre of nanotechnology research. In order to fully\nexploit its outstanding properties, a mass production method is necessary. Two\nmain routes are possible: large-scale growth or large-scale exfoliation. Here,\nwe demonstrate graphene dispersions with concentrations up to ~0.01 mg/ml by\ndispersion and exfoliation of graphite in organic solvents such as\nN-methyl-pyrrolidone. This occurs because the energy required to exfoliate\ngraphene is balanced by the solvent-graphene interaction for solvents whose\nsurface energy matches that of graphene. We confirm the presence of individual\ngraphene sheets with yields of up to 12% by mass, using absorption\nspectroscopy, transmission electron microscopy and electron diffraction. The\nabsence of defects or oxides is confirmed by X-ray photoelectron, infra-red and\nRaman spectroscopies. We can produce conductive, semi-transparent films and\nconductive composites. Solution processing of graphene opens up a whole range\nof potential large-scale applications from device or sensor fabrication to\nliquid phase chemistry.",
        "positive": "Giant spin-valve effect and chiral anomaly in antiferromagnetic\n  topological insulators Mn(Bi1-xSbx)2Te4: We report c-axis transport studies on magnetic topological insulators\nMn(Bi1-xSbx)2Te4. We performed systematic c-axis magnetoresistivity\nmeasurements under high magnetic fields (up to 35 T) on several representative\nsamples. We find the lightly hole- and lightly electron-doped samples, while\nboth having the same order of magnitude of carrier density and similar\nspin-flop transitions, exhibit sharp contrast in electronic anisotropy and\ntransport mechanism. The electronic anisotropy is remarkably enhanced for the\nlightly hole-doped sample relative to pristine MnBi2Te4 but not for the lightly\nelectron-doped sample. The lightly electron-doped sample displays a giant\nnegative longitudinal magnetoresistivity (LMR) induced by the spin-valve effect\nat the spin-flop transition field, whereas the lightly hole-doped sample\nexhibits remarkable negative LMR consistent with the chiral anomaly behavior of\na Weyl semimetal. Furthermore, we find the large negative LMR of the lightly\nhole-doped sample extends to a wide temperature range above the N\\'eel\ntemperature (T_N) where the magnetoconductivity is proportional to B^2. This\nfact, together with the short-range intralayer ferromagnetic correlation\nrevealed in isothermal magnetization measurements, suggests the possible\npresence of the Weyl state above T_N. These results demonstrate that in the\nc-axis magnetotransport of Mn(Bi1-xSbx)2Te4, the spin scattering is dominant in\nthe lightly electron-doped sample but overwhelmed by the chiral anomaly effect\nin the lightly hole-doped sample due to the presence of the Weyl state. These\nfindings extend the understanding of the transport properties of\nMn(Bi1-xSbx)2Te4."
    },
    {
        "anchor": "Stability and electronic properties of two-dimensional gallium: Two-dimensional metals offer intriguing possibilities to explore metallicity\nand other related properties in systems with reduced dimensionality. Here,\nfollowing recent experimental reports of synthesis of two-dimensional metallic\ngallium (gallenene) on insulating substrates, we conduct a computational search\nof gallenene structures using the Particle Swarm Optimization algorithm, and\nidentify stable low energy structures. Our calculations of the critical\ntemperature for conventional superconductivity yield values $\\sim 7$ K for\ngallenene. We also emulate the presence of the substrate by introducing the\nexternal confining potential and test its effect on the structures with\nunstable phonons.",
        "positive": "Infrared absorption property of silicon carbide-silica nanocables\n  synthesized by ethanol pyrolysis: A controllable synthesis method for SiC-SiO$_{2}$ nanocables has been\nproposed. The diameter of SiC core and thickness of SiO$_{2}$ shell were\nchanged by adjusting the flow ratio between Ar dilution gas and ethanol\nprecursor. With increasing the flow, the enhancement of 1137cm$^{-1}$ peak was\nobserved from fourier transform infrared spectroscopy (FTIR) spectra. This peak\nis considered to be originated from a highly disordered surface structure of\nSiO$_{2}$ shell which was enhanced with increasing the flow. The FTIR spectra\nshow the 910cm$^{-1}$ peak which is attributed to surface phonon resonance in\nthe nanostructure of SiC exited by p-polarized field component."
    },
    {
        "anchor": "Giant pressure dependence and dimensionality switching in a\n  metal-organic quantum antiferromagnet: We report an extraordinary pressure dependence of the magnetic interactions\nin the metal-organic system [(CuF$_2$(H$_2$O)$_2$)$_2$pyrazine]. At zero\npressure, this material realizes a quasi-two-dimensional (Q2D) spin-1/2\nsquare-lattice Heisenberg antiferromagnet. By high-pressure, high-field\nsusceptibility measurements we show that the dominant exchange parameter is\nreduced continuously by a factor of 2 upon compression. Above 18 kbar, a phase\ntransition occurs, inducing an orbital re-ordering that switches the\ndimensionality, transforming the Q2D lattice into weakly coupled chains (Q1D).\nWe explain the microscopic mechanisms for both phenomena by combining detailed\nx-ray and neutron diffraction results with quantitative modeling using\nspin-polarized density functional theory.",
        "positive": "Spin-Wave Relaxation in Diluted Magnetic Semiconductors within the\n  Self-Consistent Green's Function Approach: We employ a self-consistent Green's function approach to investigate the\nspin-wave relaxation \\Gamma(p) in diluted magnetic semiconductors. We find the\ntrend of the spin-wave relaxation strongly depends on the ratio of the\nitinerant and impurity spin densities. For density ratios in the\nRuderman-Kittel-Kasuya-Yosida phase, \\Gamma(p) decreases even though thermal\nfluctuations increase. On the other hand, in the strong coupling phase, an\ninteresting peak structure appears. We discuss the implications of our\nnumerical results for experiments."
    },
    {
        "anchor": "Compositional bowing of band energies and their deformation potentials\n  in strained InGaAs ternary alloys: a first-principles study: Using first-principles calculations, we show that the conduction and valence\nband energies and their deformation potentials exhibit a non-negligible\ncompositional bowing in strained ternary semiconductor alloys such as InGaAs.\nThe electronic structure of these compounds has been calculated within the\nframework of local density approximation and hybrid functional approach for\nlarge cubic supercells and special quasi-random structures, which represent two\nkinds of model structures for random alloys. We find that the predicted bowing\neffect for the band energy deformation potentials is rather insensitive to the\nchoice of the functional and alloy structural model. The direction of bowing is\ndetermined by In cations that give a stronger contribution to the formation of\nthe In$_{x}$Ga$_{1-x}$As valence band states with $x\\gtrsim 0.5$, compared to\nGa cations.",
        "positive": "Bottom-up Engineering of Diamond Nanostructures: Engineering nanostructures from the bottom up enables the creation of\ncarefully engineered complex structures that are not accessible via top down\nfabrication techniques, in particular, complex periodic structures for\napplications in photonics and sensing. In this work, we propose and demonstrate\na bottom up approach that can be adopted and utilized to controllably build\ndiamond nanostructures. A realization of periodic structures and optical\nwave-guiding is achieved by growing nanoscale single crystal diamond through a\ndefined pattern."
    },
    {
        "anchor": "Experimental measurement methods and data on irradiation of functional\n  design materials by helium ions in linear accelerator: The experimental research on the irradiation of the functional design\nmaterials by the Helium ions in the linear accelerator is conducted. The\nexperimental measurements techniques and data on the irradiation of the\nfunctional design materials by the Helium ions with the energy up to 4 MeV,\nincluding the detailed scheme of experimental measurements setup, are\npresented. The new design of accelerating structure of the IH-type such as\nPOS-4, using the method of alternate-phase focusing with the step-by-step\nchange of the synchronous phase along the focusing periods in a linear\naccelerator, is developed with the aim to irradiate the functional design\nmaterials by the Helium ions. The new design of the injector of the charged\nHelium ions with the energy of 120 KeV at the output of an accelerating tube\nand the accelerating structure of the type of POS-4 for the one time charged\nHelium ions acceleration in the linear accelerator are researched and\ndeveloped. The special chamber for the irradiation of functional design\nmaterials by the Helium ions is also created. In the process of experiment, the\ntemperature of a sample, the magnitude of current of Helium ions beam and the\nirradiation dose of sample are measured precisely. The experimental measurement\nsetup and techniques are fully tested and optimized in the course of the\nresearch on the electro-physical properties of irradiated samples and the\nthermal-desorption of Helium ions in a wide range of temperatures",
        "positive": "Stability of the Period-Doubled Core of the 90-degree Partial in Silicon: In a recent Letter [N. Lehto and S. Oberg, Phys. Rev. Lett. 80, 5568 (1998)],\nLehto and Oberg investigated the effects of strain fields on the core structure\nof the 90-degree partial dislocation in silicon, especially the influence of\nthe choice of supercell periodic boundary conditions in theoretical\nsimulations. We show that their results for the relative stability between the\ntwo structures are in disagreement with cell-size converged tight-binding total\nenergy (TBTE) calculations, which suggest the DP core to be more stable,\nregardless of the choice of boundary condition. Moreover, we argue that this\ndisagreement is due to their use of a Keating potential."
    },
    {
        "anchor": "Spatial symmetry constraint of charge-ordered kagome superconductor\n  CsV$_3$Sb$_5$: Elucidating the symmetry of intertwined orders in exotic superconductors is\nat the quantum frontier. Recent surface sensitive studies of the topological\nkagome superconductor CsV$_3$Sb$_5$ discovered a cascade 4a$_0$ superlattice\nbelow the charge density wave (CDW) ordering temperature, which can be related\nto the pair density modulations in the superconducting state. If the 4a$_0$\nphase is a bulk and intrinsic property of the kagome lattice, this would form a\nstriking analogy to the stripe order and pair density wave discovered in the\ncuprate high-temperature superconductors, and the cascade ordering found in\ntwisted bilayer graphene. High-resolution X-ray diffraction has recently been\nestablished as an ultra-sensitive probe for bulk translational\nsymmetry-breaking orders, even for short-range orders at the diffusive limit.\nHere, combining high-resolution X-ray diffraction, scanning tunneling\nmicroscopy and scanning transmission electron microscopy, we demonstrate that\nthe 4a$_0$ superstructure emerges uniquely on the surface and hence exclude the\n4a$_0$ phase as the origin of any bulk transport or spectroscopic anomaly.\nCrucially, we show that our detected 2$\\times$2$\\times$2 CDW order breaks the\nbulk rotational symmetry to C2, which can be the driver for the bulk nematic\norders and nematic surface superlattices including the 4a$_0$ phase. Our\nhigh-resolution data impose decisive spatial symmetry constraints on emergent\nelectronic orders in the kagome superconductor CsV$_3$Sb$_5$.",
        "positive": "Direct-Writing Atom-by-Atom: Direct-write processes enable the alteration or deposition of materials in a\ncontinuous, directable, sequential fashion. In this work we demonstrate an\nelectron beam direct-write process in an aberration-corrected scanning\ntransmission electron microscope. This process has several fundamental\ndifferences from conventional electron beam induced deposition techniques,\nwhere the electron beam dissociates precursor gases into chemically reactive\nproducts that bond to a substrate. Here, we use elemental tin (Sn) as a\nprecursor and employ a different mechanism to facilitate deposition. The\natomic-sized electron beam is used to generate chemically reactive point\ndefects at desired locations in a graphene substrate. Temperature control of\nthe sample is used to enable the precursor atoms to migrate across the surface\nand bond to the defect sites thereby enabling atom-by-atom direct-writing."
    },
    {
        "anchor": "Magnetoresistance of double layer hybrid system in tilted magnetic field: Magnetoresistance and Hall coefficient of a graphene layer are investigated\nin the presence of a tilted magnetic field. We consider the graphene layer is\nassembled by either another graphene layer or a two-dimensional electron gas\n(2DEG) and an interlayer electron-electron interaction is modeled within Random\nPhase Approximation. Our calculated magnetoresistances show different\ninterlayer screening effects between decoupled graphene-graphene and\ngraphene-2DEG systems. We also analyze the dependence of dielectric materials\nas well as the distance between layers on magnetoresistances. The angle\ndependence of the Hall coefficient is studied and we show that a quite large\nHall resistivity occurs in the graphene layer.",
        "positive": "Grain growth beyond the Mullins model, capturing the complex physics\n  behind universal grain size distributions: Grain growth experiments on thin metallic films have shown the geometric and\ntopological characteristics of the grain structure to be universal and\nindependent of many experimental conditions. The universal size distribution,\nhowever, is found to differ both qualitatively and quantitatively from the\nstandard Mullins curvature driven model of grain growth; with the experiments\nexhibiting an excess of small grains (termed an \"ear\") and an excess of very\nlarge grains (termed a \"tail\") compared with the model. While a plethora of\nextensions of the Mullins model have been proposed to explain these\ncharacteristics, none have been successful. In this work, large scale\nsimulations of a model that resolves the atomic scale on diffusive time scales,\nthe phase field crystal model, is used to examine the complex phenomena of\ngrain growth. The results are in remarkable agreement with the experimental\nresults, recovering the characteristic \"ear\" and \"tail\" features of the\nexperimental grain size distribution. The simulations also indicate that while\nthe geometric and topological characteristics are universal, the dynamic growth\nexponent is not."
    },
    {
        "anchor": "Simultaneous prediction of atomic structure and stability of\n  nanoclusters in a wide area of compositions: We present a universal method for the large-scale prediction of the atomic\nstructure of clusters. Our algorithm performs the joint evolutionary search for\nall clusters in a given area of the compositional space and takes advantage of\nstructural similarities frequently observed in clusters of close compositions.\nThe resulting speedup is up to 50 times compared to current methods. This\nenables the first-principles studies of multi-component clusters with full\ncoverage of a wide range of compositions. As an example, we report an\nunprecedented first-principles global optimization of 315 SinOm clusters with\nn<=15 and m<=20. The obtained map of Si-O cluster stability shows the existence\nof both expected (SiO2)n and unexpected (e.g. Si4O18) stable (\"magic\")\nclusters, which can be important for miscellaneous applications.",
        "positive": "Magnon Current Generation by Dynamical Distortion: The interaction between spin and nanomechanical degrees of freedom attracts\ninterest from the viewpoint of basic science and device applications. We study\nthe magnon current induced by the torsional oscillation of ferromagnetic\nnanomechanical cantilever. We find that a finite Dzyaloshinskii-Moriya (DM)\ninteraction emerges by the torsional oscillation, which is described by the\nspin gauge field, and the DM interaction leads to the detectably-large magnon\ncurrent with frequency same as that of the torsional oscillation. Our theory\npaves the way for studying torsional spin-nanomechanical phenomena by using the\nspin gauge field."
    },
    {
        "anchor": "Thermal Stability of Metallic Single-Walled Carbon Nanotubes: An O(N)\n  Tight-Binding Molecular Dynamics Simulation Study: Order(N) Tight-Binding Molecular Dynamics (TBMD) simulations are performed to\ninvestigate the thermal stability of (10,10) metallic Single-Walled Carbon\nNanotubes (SWCNT). Periodic boundary conditions (PBC) are applied in axial\ndirection. Velocity Verlet algorithm along with the canonical ensemble\nmolecular dynamics (NVT) is used to simulate the tubes at the targeted\ntemperatures. The effects of slow and rapid temperature increases on the\nphysical characteristics, structural stability and the energetics of the tube\nare investigated and compared. Simulations are carried out starting from room\ntemperature and the temperature is raised in steps of 300K. Stability of the\nsimulated metallic SWCNT is examined at each step before it is heated to higher\ntemperatures. First indication of structural deformation is observed at 600K.\nFor higher heat treatments the deformations are more pronounced and the bond\nbreaking temperature is reached around 2500K. Gradual (slow) heating and\nthermal equilibrium (fast heating) methods give the value of radial thermal\nexpansion coefficient in the temperature range between 300K-600K as\n0.31x10^{-5}(1/K) and 0.089x10^{-5}(1/K), respectively. After 600K, both\nmethods give the same value of 0.089x10^{-5}(1/K). The ratio of the total\nenergy per atom with respect to temperature is found to be 3x10^{-4} eV/K.",
        "positive": "Birth, Growth and Death of an Antivortex during the Propagation of a\n  Transverse Domain Wall in Magnetic Nanostrips: Antivortex birth, growth and death due to the propagation of a transverse\ndomain wall (DW) in magnetic nanostrips are observed and analyzed. Antivortex\nformation is an intrinsic process of a strawberry-like transverse DW originated\nfrom magnetostatic interaction. Under an external magnetic field, DW in a wider\nwidth region tends to move faster than that of a narrower part. This speed\nmismatch tilts and elongates DW centre line. An antivortex is periodically born\nnear the tail of the DW centre line. The antivortex either moves along the\ncentre line and dies on the other side of the strip, or grows to its maximum\nsize, detaches itself from the DW, and vanishes eventually. The former route\nreverses the polarity of DW while the later keeps the DW polarity unchanged.\nThe evolution of the DW structures is analyzed using winding numbers assigned\nto each topological defects. The phase diagram in the field-width plane is\nobtained and discussed."
    },
    {
        "anchor": "Electrical transport in nano-thick ZrTe$_5$ sheets: from three to two\n  dimensions: ZrTe$_5$ is a newly discovered topological material. Shortly after a single\nlayer ZrTe$_5$ had been predicted to be a two-dimensional topological\ninsulator, a handful of experiments have been carried out on bulk ZrTe$_5$\ncrystals, which however suggest that its bulk form may be a three-dimensional\ntopological Dirac semimetal. We report the first transport study on ultra thin\nZrTe$_5$ flakes down to 10 nm. A significant modulation of the characteristic\nresistivity maximum in the temperature dependence by thickness has been\nobserved. Remarkably, the metallic behavior, occurring only below about 150 K\nin bulk, persists to over 320 K for flakes less than 20 nm thick. Furthermore,\nthe resistivity maximum can be greatly tuned by ionic gating. Combined with the\nHall resistance, we identify contributions from a semiconducting and a\nsemimetallic bands. The enhancement of the metallic state in thin flakes are\nconsequence of shifting of the energy bands. Our results suggest that the band\nstructure sensitively depends on the film thickness, which may explain the\ndivergent experimental observations on bulk materials.",
        "positive": "Revealing the ultra-fast domain wall motion in Manganese Gold through\n  permalloy capping: Antiferromagnets offer much faster dynamics compared to their ferromagnetic\ncounterparts but their order parameter is extremely difficult to detect and\ncontrol. So far, controlling the N\\'eel order parameter electrically is limited\nto only very few materials where N\\'eel spin-orbit torques are allowed by\nsymmetry. In this work, we show that coupling a thin ferromagnet (permalloy)\nlayer on top of an antiferromagnet (Mn$_2$Au) solves a major roadblock -- the\ncontrolled reading, writing, and manipulation of antiferromagnetic domains. We\nconfirm by atomistic spin dynamics simulations that the domain wall patterns in\nthe Mn$_2$Au are imprinted on the permalloy, therefore allowing for indirect\nimaging of the N\\'eel order parameter. Our simulations show that the coupled\ndomain wall structures in Mn$_2$Au-Py bilayers can be manipulated by either\nacting on the N\\'eel order parameter via N\\'eel spin-orbit torques or by acting\non the magnetisation (the ferromagnetic order parameter) via magnetic fields.\nIn both cases, we predict ultra-high domain wall speeds on the order of 8.5\nkm/s. Thus, employing a thin ferromagnetic layer has the potential to easily\ncontrol the N\\'eel order parameter in antiferromagnets even where N\\'eel\nspin-orbit torques are forbidden by symmetry. The controlled manipulation of\nthe antiferromagnetic order parameter provides a promising basis for the\ndevelopment of high-density storage and efficient computing technologies\nworking in the THz regime."
    },
    {
        "anchor": "Covalently Binding the Photosystem I to Carbon Nanotubes: We present a chemical route to covalently couple the photosystem I (PS I) to\ncarbon nanotubes (CNTs). Small linker molecules are used to connect the PS I to\nthe CNTs. Hybrid systems, consisting of CNTs and the PS I, promise new\nphoto-induced transport phenomena due to the outstanding optoelectronic\nproperties of the robust cyanobacteria membrane protein PS I.",
        "positive": "A regression-based feature selection study of the Curie temperature of\n  transition-metal rare-earth compounds: prediction and understanding: The Curie temperature ($T_C$) of binary alloy compounds consisting of 3$d$\ntransition-metal and 4$f$ rare-earth elements is analyzed by a machine learning\ntechnique. We first demonstrate that nonlinear regression can accurately\nreproduce $T_C$ of the compounds. The prediction accuracy for $T_C$ is\nmaximized when five to ten descriptors are selected, with the rare-earth\nconcentration being the most relevant. We then discuss an attempt to utilize a\nregression-based model selection technique to learn the relation between the\ndescriptors and the actuation mechanism of the corresponding physical\nphenomenon, i.e., $T_C$ in the present case."
    },
    {
        "anchor": "New potential super-incompressible phase of ReN$_{2}$: The structural, elastic, and electronic properties of ReN$_{2}$ are\ninvestigated by first-principles calculations with density functional theory.\nThe obtained orthorhombic $Pbcn$ structure is energetically the most stable\nstructure at ambient pressure. ReN$_{2}$ is a metallic, superincompressible\nsolid and presents a rather elastic anisotropy. The estimated Debye temperature\nand hardness are 735 K and 17.1 GPa, respectively. Its estimated hardness is\ncomparative to that of Si$_{3}$N$_{4}$.",
        "positive": "Growth evolution of self-affine thermally evaporated KBr thin films: A\n  fractal assessment: In this article, fractal concepts were used to explore the thermally\nevaporated potassium bromide thin films of different thicknesses 200, 300, and\n500 nm respectively; grown on aluminium substrates at room temperature. The\nself-affine or self similar nature of growing surfaces was investigated by\nautocorrelation function and obtained results are compared with the\nmorphological envelope method. Theoretical estimations revealed that the global\nsurface parameters such as, interface width and lateral correlation length are\nmonotonically decreased with increasing film thickness. Also, from height\nprofile and A-F plots, it has been perceived that irregularity/ complexity of\ngrowing layers was significantly influenced by thickness. On the other hand,\nthe fractal dimension and local roughness exponent, estimated by height-height\ncorrelation function, do not suggest such dependency."
    },
    {
        "anchor": "Experimental evaluation and thermodynamic assessment of the LiF-LuF3\n  phase diagram: The phase diagram of the system LiF-LuF3 has been revised using thermal\nanalysis. Specific heat capacity and enthalpy of phase transition and fusion\nwere measured by differential scanning calorimetry for all compounds belonging\nto the system. A thermodynamic optimization of the LiF-LuF3 phase diagram was\nperformed by fitting the Gibbs energy functions to experimental data that were\ntaken from the literature or measured in this work. Excess energy terms, which\ndescribe the effect of interaction between the two fluoride compounds in the\nliquid solution, were expressed by the Redlich-Kister polynomial function. The\ntheoretical phase diagram assessed was in suitable agreement with the\nre-evaluated experimental data.",
        "positive": "A method to quantify molecular diffusion within thin solvated polymer\n  films: A case study on films of natively unfolded nucleoporins: We present a method to probe molecular and nanoparticle diffusion within\nthin, solvated polymer coatings. The device exploits the confinement with\nwell-defined geometry that forms at the interface between a planar and a\nhemi-spherical surface (of which at least one is coated with polymers) in close\ncontact, and uses this confinement to analyse diffusion processes without\ninterference of exchange with and diffusion in the bulk solution. With this\nmethod, which we call plane-sphere confinement microscopy (PSCM), information\nregarding the partitioning of molecules between the polymer coating and the\nbulk liquid is also obtained. Thanks to the shape of the confined geometry,\ndiffusion and partitioning can be mapped as a function of compression and\nconcentration of the coating in a single experiment. The method is versatile\nand can be integrated with conventional optical microscopes, and thus should\nfind widespread use in the many application areas exploiting functional polymer\ncoatings. We demonstrate the use of PSCM using brushes of natively unfolded\nnucleoporin domains rich in phenylalanine-glycine repeats (FG domains). A\nmeshwork of FG domains is known to be responsible for the selective transport\nof nuclear transport receptors (NTR) and their macromolecular cargos across the\nnuclear envelope that separates the cytosol and the nucleus of living cells. We\nfind that the selectivity of NTR uptake by FG domain films depends sensitively\non FG domain concentration, and that the interaction of NTRs with FG domains\nobstructs NTR movement only moderately. These observations contribute important\ninformation to better understand the mechanisms of selective NTR transport."
    },
    {
        "anchor": "On the rotational alignment of graphene domains grown on Ge(110) and\n  Ge(111): We have used low-energy electron diffraction and microscopy to compare the\ngrowth of graphene on hydrogen-free Ge(111) and Ge(110) from an atomic carbon\nflux. Growth on Ge(110) leads to significantly better rotational alignment of\ngraphene domains with the substrate. To explain the poor rotational alignment\non Ge(111), we have investigated experimentally and theoretically how the\nadatom reconstructions on Ge interact with graphene. We find that the ordering\ntransition of the adatom reconstruction of Ge(111) is not significantly\nperturbed by graphene. Density functional theory calculations show that\ngraphene on reconstructed Ge(110) has large-amplitude corrugations, whereas it\nis remarkably flat on reconstructed Ge(111). We argue that the absence of\ncorrugations prevents graphene islands from locking into a preferred\norientation.",
        "positive": "Excitation of self-localized spin-wave \"bullets\" by spin-polarized\n  current in in-plane magnetized magnetic nano-contacts: a micromagnetic study: It was shown by micromagnetic simulation that a current-driven in-plane\nmagnetized magnetic nano-contact, besides a quasi-linear propagating\n(\"Slonczewski\") spin wave mode, can also support a nonlinear self-localized\nspin wave \"bullet\" mode that exists in a much wider range of bias currents. The\nfrequency of the \"bullet\" mode lies below the spectrum of linear propagating\nspin waves, which makes this mode evanescent and determines its spatial\nlocalization. The threshold current for the excitation of the self-localized\n\"bullet\" is substantially lower than for the linear propagating mode, but\nfinite-amplitude initial perturbations of magnetization are necessary to\ngenerate a \"bullet\" in our numerical simulations, where thermal fluctuations\nare neglected. Consequently, in these simulations the hysteretic switching\nbetween the propagating and localized spin wave modes is found when the bias\ncurrent is varied."
    },
    {
        "anchor": "Identifying the ground state structures of point defects in solids: Point defects are a universal feature of crystalline materials. Their\nidentification is often addressed by combining experimental measurements with\ntheoretical models. The standard approach of simulating defects is, however,\nprone to missing the ground state atomic configurations associated with\nenergy-lowering reconstructions from the idealised crystallographic\nenvironment. Missed ground states compromise the accuracy of calculated\nproperties. To address this issue, we report an approach to efficiently\nnavigate the defect configurational landscape using targeted bond distortions\nand rattling. Application of our workflow to a range of materials ($\\rm CdTe$,\n$\\rm GaAs$, $\\rm Sb_2S_3$, $\\rm Sb_2Se_3$, $\\rm CeO_2$, $\\rm In_2O_3$, $\\rm\nZnO$, anatase-$\\rm TiO_2$) reveals symmetry breaking in each host crystal that\nis not found via conventional local minimisation techniques. The point defect\ndistortions are classified by the associated physico-chemical factors. We\ndemonstrate the impact of these defect distortions on derived properties,\nincluding formation energies, concentrations and charge transition levels. Our\nwork presents a step forward for quantitative modelling of imperfect solids.",
        "positive": "Surface Plasmon Resonance of Dumb-bell Nano-structure: We present an intuitive theoretical description of the optical properties of\ncomplex metal nano-structure, consisting of two nano-shells connected by a\nnano-rod giving a dumb-bell like appearance. The simulations were done using\nFinite Element Method. The effect of the nano-rod length and radius as also the\ndimensions of the nano-shells were analyzed. The absorption spectra as in peak\npositions and intensities have been found to have a strong dependence on the\ngeometrical parameters of the dumb-bell. This study provides evidence that the\nlocalized surface plasmon modes play a key role in the broadband light\nharvesting capabilities of these nanostructures and is promising for a wide\nrange of practical applications, for example in surface-enhanced\nspectroscopies."
    },
    {
        "anchor": "Discovery of spin glass in maple-leaf lattice Na2Mn3O7: Geometrically frustrated magnetism is commonly studied in triangular and\nKagome lattices. A rare lattice which exhibits frustration is obtained by\ndepleting 1/7 of the sites from a triangular lattice and is called a maple-leaf\nlattice. We report the magnetic properties of an oxide material with a\nmaple-leaf lattice: Na2Mn3O7. Structural studies suggest slight lattice\ndistortion and density functional theory predicts energetic near-degeneracy\nbetween ferromagnetism and antiferromagnetic phases which points towards\ncompeting magnetic orderings at low temperatures. In addition, from our\nmagnetic studies, we discovered a non-equilibrium spin state below ~50 K. The\nbifurcation of field-cooled and zero-field-cooled magnetization curves,\nhysteresis of ~16 kOe at 2 K, and time-dependent magnetization response is\nconsistent with a spin glass state. To our knowledge this is the first report\nof such a state in materials with a MLL. This is a promising discovery towards\nusing spin glass to transport angular momentum or spins for applications low\npower spintronics.",
        "positive": "Hybrid Interface States and Spin Polarization at Ferromagnetic\n  Metal-Organic Heterojunctions: Interface Engineering for Efficient Spin\n  Injection in Organic Spintronics: Ferromagnetic metal-organic semiconductor (FM-OSC) hybrid interfaces have\nshown to play an important role for spin injection in organic spintronics.\nHere, 11,11,12,12-tetracyanonaptho-2,6-quinodimethane (TNAP) is introduced as\nan interfacial layer in Co-OSCs heterojunction with an aim to tune the spin\ninjection. The Co/TNAP interface is investigated by use of X-ray and\nultraviolet photoelectron spectroscopy (XPS/UPS), near edge X-ray absorption\nfine structure (NEXAFS) and X-ray magnetic circular dichroism (XMCD). Hybrid\ninterface states (HIS) are observed at Co/TNAP interface resulting from\nchemical interaction between Co and TNAP. The energy level alignment at\nCo/TNAP/OSCs interface is also obtained, and a reduction of the hole injection\nbarrier is demonstrated. XMCD results confirm sizeable spin polarization at the\nCo/TNAP hybrid interface."
    },
    {
        "anchor": "A study on the thermal conductance of interface between dissimilar\n  metals: Whether diffuse mismatch model for electrons (DMMe) hold true in more general\ncases remains largely unexplored, especially in cases where at least one\nmaterial does not behave like a free-electron metal and/or the interface is\nsmooth enough to allow non-diffuse transmission of electrons. In this study,\nDMMe was proposed to predict the thermal conductance of metal-metal interfaces.\nA set of aluminum-X samples (X = Cu, Ag, Fe, Ni) were grown and the time domain\nthermoreflectance (TDTR) technique was used to measure the metal-metal\ninterface conductance. It was then compared to the two variants of the\nDMMe-using both a crude theory based on free-electron metals and accurate band\nstructures provided by density functional theory.",
        "positive": "Remarkable band gap renormalization via dimensionality of the layered\n  material C3B: Layer-dependent electronic and structural properties of emerging graphitic\ncarbon boron compound C3B are investigated using both density functional theory\nand the GW approximation. We discover that, in contrast to a moderate\nquasiparticle band gap of 2.55 eV for monolayer C3B, the calculated\nquasiparticle band gap of perfectly stacked bulk phase C3B is as small as 0.17\neV. Therefore, our results suggest that layered material C3B exhibits a\nremarkably large band gap renormalization of over 2.3 eV due to the interlayer\ncoupling and screening effects, providing a single material with an\nextraordinary band gap tunability. The quasiparticle band gap of monolayer C3B\nis also over 1.0 eV larger than that of C3N, a closely related two-dimensional\nsemiconductor. Detailed inspections of the near-edge electronic states reveal\nthat the conduction and valence band edges of C3B are formed by out-of-plane\nand in-plane electronic states, respectively, suggesting an interesting\npossibility of tuning the band edges of such layered material separately by\nmodulating the in-plane and out-of-plane interactions."
    },
    {
        "anchor": "Materials selection rules for amorphous complexion formation in binary\n  metallic alloys: Complexions are phase-like interfacial features that can influence a wide\nvariety of properties, but the ability to predict which material systems can\nsustain these features remains limited. Amorphous complexions are of particular\ninterest due to their ability to enhance diffusion and damage tolerance\nmechanisms, as a result of the excess free volume present in these structures.\nIn this paper, we propose a set of materials selection rules aimed at\npredicting the formation of amorphous complexions, with an emphasis on (1)\nencouraging the segregation of dopants to the interfaces and (2) lowering the\nformation energy for a glassy structure. To validate these predictions, binary\nCu-rich metallic alloys encompassing a range of thermodynamic parameter values\nwere created using sputter deposition and subsequently heat treated to allow\nfor segregation and transformation of the boundary structure. All of the alloys\nstudied here experienced dopant segregation to the grain boundary, but\nexhibited different interfacial structures. Cu-Zr and Cu-Hf formed nanoscale\namorphous intergranular complexions while Cu-Nb and Cu-Mo retained crystalline\norder at their grain boundaries, which can mainly be attributed to differences\nin the enthalpy of mixing. Finally, using our newly formed materials selection\nrules, we extend our scope to a Ni-based alloy to further validate our\nhypothesis, as well as make predictions for a wide variety of transition metal\nalloys.",
        "positive": "Negative refraction in natural ferromagnetic metals: It is generally believed that Veselago's criterion for negative refraction\ncannot be fulfilled in natural materials. However, considering imaginary parts\nof the permittivity ({\\epsilon}) and permeability ({\\mu}) and for metals at not\ntoo high frequencies the general condition for negative refraction becomes\nextremely simple: Re({\\mu}) < 0 --> Re(n) < 0. Here we demonstrate\nexperimentally that in such natural metals as pure Co and FeCo alloy the\nnegative values of the refractive index are achieved close to the frequency of\nthe ferromagnetic resonance. Large values of the negative refraction can be\nobtained at room temperature and they can easily be tuned in moderate magnetic\nfields."
    },
    {
        "anchor": "Partial ablation of Ti/Al nano-layer thin film by single femtosecond\n  laser pulse: The effects of ultra-short laser pulses on reactive Ti/Al nano-layered thin\nfilm were investigated. The thin film composed of alternated titanium and\naluminium nano-layers, was deposited by ion-sputtering. Single pulse\nirradiation was conducted in the air with focused and linearly polarized\nfemtosecond laser beam - of 1026 nm wavelength and pulse duration of 170 fs.\nLaser induced composition and morphological changes, using different microscopy\ntechniques and energy dispersive X-ray spectroscopy, were investigated.\nFollowing results were obtained: (i) one step partial/selective ablation of\nupper Ti layer from nano-layer Ti/Al at low laser fluence and (ii) two step\nablation or entire ablation of nano-layer Ti/Al at higher laser fluence. Single\npulse selective ablation of the upper Ti layer was confirmed based on profiling\n(AFM) along the ablation steps and reduction of Ti concentration (EDX) in the\nablated areas. Ablation threshold was estimated using well known procedure for\nultra-short laser pulses - spot diameter square versus logarithm of pulse\nenergy. To interpret the experimental observations, simulations have been\nperformed to explore the thermal response of the multiple layered structure\n(Ti(5x(Al/Ti))) after irradiation with a characteristic value of single laser\npulse of fluence F = 320 mJ/cm2. The results are in agreement with the\ncalculations.",
        "positive": "Conditions for free magnetic monopoles in nanoscale square arrays of\n  dipolar spin ice: We study a modified frustrated dipolar array recently proposed by M\\\"{o}ller\nand Moessner [Phys. Rev. Lett. \\textbf{96}, 237202 (2006)], which is based on\nan array manufactured lithographically by Wang \\emph{et al.} [Nature (London)\n\\textbf{439}, 303 (2006)] and consists of introducing a height offset $h$\nbetween islands (dipoles) pointing along the two different lattice directions.\nThe ground-states and excitations are studied as a function of $h$. We have\nfound, in qualitative agreement with the results of M\\\"{o}ller and Moessner,\nthat the ground-state changes for $h>h_{1}$, where $h_{1}= 0.444a$ ($a$ is the\nlattice parameter or distance between islands). In addition, the excitations\nabove the ground-state behave like magnetic poles but confined by a string,\nwhose tension decreases as $h$ increases, in such a way that for $h\\approx h_1$\nits value is around 20 times smaller than that for $h=0$. The system exhibits\nan anisotropy in the sense that the string tension and magnetic charge depends\nsignificantly on the directions in which the monopoles are separated. In turn,\nthe intensity of the magnetic charge abruptly changes when the monopoles are\nseparated along the direction of the longest axis of the islands. Such a gap is\nattributed to the transition from the anti to the ferromagnetic ground-state\nwhen $h=h_1$."
    },
    {
        "anchor": "Modeling the actinides with disordered local moments: A first-principles disordered local moment (DLM) picture within the\nlocal-spin-density and coherent potential approximations (LSDA+CPA) of the\nactinides is presented. The parameter free theory gives an accurate description\nof bond lengths and bulk modulus. The case of $\\delta$-Pu is studied in\nparticular and the calculated density of states is compared to data from\nphoto-electron spectroscopy. The relation between the DLM description, the\ndynamical mean field approach and spin-polarized magnetically ordered modeling\nis discussed.",
        "positive": "Carrier screening controls transport in conjugated polymers at high\n  doping concentrations: Transport properties of doped conjugated polymers (CPs) have been widely\nanalyzed with the Gaussian Disorder Model (GDM) in conjunction with hopping\ntransport between localized states. These models reveal that even in highly\ndoped CPs, a majority of carriers are still localized because dielectric\npermittivity of CPs is well below that of inorganic materials, making Coulomb\ninteractions between carriers and dopant counter-ions much more pronounced.\nHowever, previous studies within the GDM did not consider the role of screening\nthe dielectric interactions by carriers. Here we implement carrier screening in\nthe Debye-H\\\"uckel formalism in our calculations of dopant-induced energetic\ndisorder, which modifies the Gaussian density of states (DOS). Then we solve\nthe Pauli Master Equation using Miller-Abrahams hopping rates with states from\nthe resulting screened DOS to obtain conductivity and Seebeck coefficient\nacross a broad range of carrier concentrations and compare them to\nmeasurements. Our results show that screening has significant impact on the\nshape of the DOS and consequently on carrier transport, particularly at high\ndoping. We prove that the slope of Seebeck coefficient vs electric\nconductivity, which was previously thought to be universal, is impacted by\nscreening and decreases for systems with small dopant-carrier separation,\nexplaining our measurements. We also show that thermoelectric power factor is\nunderestimated by a factor of $\\sim10$ at higher doping concentrations if\nscreening is neglected. We conclude that carrier screening plays a crucial role\nin curtailing dopant-induced energetic disorder, particularly at high carrier\nconcentrations."
    },
    {
        "anchor": "Proton distribution visualization in perovskite nickelate devices\n  utilizing nanofocused X-rays: We use a 30-nm x-ray beam to study the spatially resolved properties of a\nSmNiO$_3$-based nanodevice that is doped with protons. The x-ray absorption\nspectra supported by density-functional theory (DFT) simulations show partial\nreduction of nickel valence in the region with high proton concentration, which\nleads to the insulating behavior. Concurrently, x-ray diffraction reveals only\na small lattice distortion in the doped regions. Together, our results directly\nshow that the knob which proton doping modifies is the electronic valency, and\nnot the crystal lattice. The studies are relevant to on-going efforts to\ndisentangle structural and electronic effects across metal-insulator phase\ntransitions in correlated oxides.",
        "positive": "Cascade morphology transition in bcc metals: Energetic atom collisions in solids induce shockwaves with complex\nmorphologies. In this paper, we establish the existence of a morphological\ntransition in such cascades. The order parameter of the morphology is defined\nas the exponent, $b$, in the defect production curve as a function of cascade\nenergy ($N_F \\sim E_{MD}^b$). Response of different bcc metals can be compared\nin a consistent energy domain when the energy is normalized by the transition\nenergy, $\\mu$, between the high- and the low-energy regime. Using Cr, Fe, Mo\nand W data, an empirical formula of $\\mu$ as a function of displacement\nthreshold energy, $E_d$, is presented for bcc metals."
    },
    {
        "anchor": "BCS-BEC crossover and effects of density fluctuations in a two-component\n  Fermi gas loaded on an optical lattice: We investigate the superfluid phase transition in a gas of Fermi atoms loaded\non a three-dimensional optical lattice. When the lattice potential is strong,\nthis system can be well described by an attractive Hubbard model. In this\nmodel, we calculate the superfluid phase transition temperature Tc, including\nboth superfluid and (spin and charge) density fluctuations within the\nself-consistent t-matrix theory and fluctuation exchange approximation,\nrespectively. Since we treat these fluctuations in a consistent manner, our\ntheory satisfies the required particle-hole symmetry over the entire BCS-BEC\ncrossover region. We show that charge density fluctuations compete against\nsuperfluid fluctuations near the half-filling, leading to the suppression of\nTc. As a result, the maximum Tc is obtained away the half-filling. Since the\nstrong density fluctuations originate from the nesting property of the Fermi\nsurface at the half filling (which is absent in a uniform gas with no lattice\npotential), our results would be useful in considering lattice effects on\nstrong-coupling superfluidity.",
        "positive": "Spectroscopic evidence for the convergence of lower and upper valence\n  bands of PbQ (Q=Te, Se, S) with rising temperature: We have conducted temperature dependent Angle Resolved Photoemission\nSpectroscopy (ARPES) study of the electronic structure of n-, p- type PbTe,\nPbSe and PbS, which are pre- mier thermoelectric materials. Our ARPES\nmeasurements on them provide direct evidence for the light hole upper valence\nbands (UVBs) and the so-called heavy hole lower valence bands (LVBs), and an\nunusual temperature dependent relative movement between their band maxima\nleading to a monotonic decrease in the energy separation between LVBs and UVBs\nwith increase in temperature. This enables convergence of these valence bands\nand consequently, an effective increase in the valley degeneracy in PbQ at\nhigher temperatures, which has long been speculated to be the driving factor\nbehind their extraordinary thermoelectric performance."
    },
    {
        "anchor": "Intrinsic Electron-Phonon Resistivity in Bi2Se3 in the Topological\n  Regime: We measure the temperature-dependent carrier density and resistivity of the\ntopological surface state of thin exfoliated Bi2Se3 in the absence of bulk\nconduction. When the gate-tuned chemical potential is near or below the Dirac\npoint the carrier density is strongly temperature dependent reflecting thermal\nactivation from the nearby bulk valence band, while above the Dirac point,\nunipolar n-type surface conduction is observed with negligible thermal\nactivation of bulk carriers. In this regime linear resistivity vs. temperature\nreflects intrinsic electron-acoustic phonon scattering. Quantitative comparison\nwith a theoretical transport calculation including both phonon and disorder\neffects gives the ratio of deformation potential to Fermi velocity D/\\hbarvF =\n4.7 {\\AA}-1. This strong phonon scattering in the Bi2Se3 surface state gives\nintrinsic limits for the conductivity and charge carrier mobility at room\ntemperature of ~550 {\\mu}S per surface and ~10,000 cm2/Vs.",
        "positive": "The AFLOW Fleet for Materials Discovery: The traditional paradigm for materials discovery has been recently expanded\nto incorporate substantial data driven research. With the intent to accelerate\nthe development and the deployment of new technologies, the AFLOW Fleet for\ncomputational materials design automates high-throughput first principles\ncalculations, and provides tools for data verification and dissemination for a\nbroad community of users. AFLOW incorporates different computational modules to\nrobustly determine thermodynamic stability, electronic band structures,\nvibrational dispersions, thermo-mechanical properties and more. The AFLOW data\nrepository is publicly accessible online at aflow.org, with more than 1.7\nmillion materials entries and a panoply of queryable computed properties. Tools\nto programmatically search and process the data, as well as to perform online\nmachine learning predictions, are also available."
    },
    {
        "anchor": "Altermagnetism and magnetic groups with pseudoscalar electron spin: We revise existing group-theoretical approaches for a treatment of\nnonrelativistic collinear magnetic systems with perfect translation invariance.\nWe show that full symmetry groups of these systems, which contain elements with\nindependent rotations in the spin and configuration spaces (spin groups), can\nbe replaced by magnetic groups consisting of elements with rotations acting\nonly on position vectors. This reduction follows from modified transformation\nproperties of electron spin, which in the considered systems becomes\neffectively a pseudoscalar quantity remaining unchanged upon spatial operations\nbut changing its sign due to an operation of antisymmetry. We introduce a\nunitary representation of the relevant magnetic point groups and use it for a\nclassification of collinear magnets from the viewpoint of\nantiferromagnetism-induced spin splitting of electron bands near the center of\nBrillouin zone. We prove that the recently revealed different altermagnetic\nclasses correspond in a unique way to all nontrivial magnetic Laue classes,\ni.e., to the Laue groups containing the operation of antisymmetry only in\ncombination with a spatial rotation. Four of these Laue classes are found\ncompatible with a nonzero spin conductivity. Subsequent inspection of a simple\nmodel allows us to address briefly the physical mechanisms responsible for the\nspin splitting in real systems.",
        "positive": "Galvanomagnetic effects and manipulation of antiferromagnetic\n  interfacial uncompensated magnetic moment in exchange-biased bilayers: In this work, IrMn$_{3}$/insulating-Y$_{3}$Fe$_{5}$O$_{12}$ exchange-biased\nbilayers are studied. The behavior of the net magnetic moment $\\Delta m_{AFM}$\nin the antiferromagnet is directly probed by anomalous and planar Hall effects,\nand anisotropic magnetoresistance. The $\\Delta m_{AFM}$ is proved to come from\nthe interfacial uncompensated magnetic moment. We demonstrate that the exchange\nbias and rotational hysteresis are induced by the irreversible switching of the\n$\\Delta m_{AFM}$. In the training effect, the $\\Delta m_{AFM}$ changes\ncontinuously. This work highlights the fundamental role of the $\\Delta m_{AFM}$\nin the exchange bias and facilitates the manipulation of antiferromagnetic\nspintronic devices."
    },
    {
        "anchor": "Strain Induced Enhanced Photocatalytic Activities in Layered Two\n  Dimensional C2N/MoS2 Heterostructure: A Meta-GGA Study: The improved photocatalytic water splitting using 2D materials has\ntechnological importance for economically viable renewable energy. The present\nstudy focuses on the effect of uniaxial, biaxial, and vertical strain on the\nenergy gap and band edge positions of C2N/MoS2 van der Waals heterostructures\nthrough first-principles density functional theory using PBE and SCAN\nfunctionals. The calculations establish that SCAN functional provides\ncomparatively much better results as compared to the PBE for the band gap and\nband alignment study. The heterostructure exhibits a type- II band alignment\nwhich is beneficial for the efficient separation of charge carriers. For a good\nphotocatalyst, the band edge positions should straddle the water redox\npotentials. It is observed that for both compressive and tensile vertical\nstrain, the water redox potential values lie within the valence band maximum\n(VBM) and conduction band minimum (CBM) of the heterostructure. On the other\nhand, for uniaxial and biaxial strain, the system can be used as a useful\nphotocatalyst only for larger compressive strain, whereas for tensile strain,\nthe energy gap between VBM and CBM keeps on decreasing and lie within the water\noxidation/reduction potential. Our study also establishes that the meta-GGA\nSCAN functional shows similar results as compared to the computationally\nexpensive hybrid HSE functionals. The present work can be extremely useful for\nexperimentalists to design artificial heterostructure devices for better\nperformance in photocatalytic water splitting.",
        "positive": "Impact of annealing temperature on structural, electrical and optical\n  properties of epitaxial GaN thin films grown on sapphire substrates by PA-MBE: We report epitaxial growth and characterization of GaN thin films on sapphire\n(0001) substrates using low temperature GaN intermediate layer by plasma\nassisted molecular beam epitaxy (PA-MBE) technique. As grown and annealed GaN\nthin films were studied by high- resolution X-ray diffraction (HRXRD), atomic\nforce microscopy (AFM), Hall Effect and photoluminescence (PL). It has been\nfound that there is a significant improvement in the quality of the GaN films\nafter annealing at 725 \\degree C in terms of electron mobility, full width at\nhalf maximum (FWHM) of omega ({\\omega}) scan around (0002) XRD peak of GaN\nfilms. Screw dislocation density obtained from the FWHM of GaN (0002) \\omega\nscan and etch pitch density calculated from AFM image are 6.4 \\times 10^8\ncm^{-2} and 5.1\\times 10^8 cm^{-2} respectively. In PL measurement, FWHM of\nnear band edge (NBE) peak of GaN films has been found to be 30 meV."
    },
    {
        "anchor": "Design and construction of a novel tribometer with on-line topography\n  and wear measurement: We present a novel experimental platform that links topographical and\nmaterial changes with the friction and wear behavior of oil-lubricated metal\nsurfaces. This concept combines state-of-the-art methods for the analysis of\nthe surface topography on the micro- and nano-scale with the online measurement\nof wear. At the same time, it allows for frictional and lateral force\ndetection. Information on the topography of one of the two surfaces is gathered\nin-situ with a 3D holography microscope at a maximum frequency of 15 fps and\nhigher resolution images are provided at defined time intervals by an atomic\nforce microscope (AFM). The wear measurement is conducted on-line by means of\nradio nuclide technique (RNT). The quantitative measurement of the lateral and\nfrictional forces is conducted with a custom-built 3D force sensor. The\nsurfaces can be lubricated with an optically transparent oil or water. The\nstability and precision of the setup have been tested in a model experiment.\nThe results show that the exact same position can be relocated and examined\nafter each load cycle. Wear and topography measurements were performed with a\nradioactive labeled iron pin sliding against an iron plate.",
        "positive": "Exchange-induced phase separation in Ni-Cu films: Magneto-structural properties of films of diluted ferromagnetic alloys\nNi$_x$Cu$_{1-x}$ in the concentration range $0.7 < x < 1.0$ are studied\nexperimentally. Films deposited by magnetron sputtering show partial phase\nseparation, as evidenced by structural analysis and ferromagnetic resonance\nmeasurements. The phase diagram of the Ni$_x$Cu$_{1-x}$ bulk system is obtained\nusing numerical theoretical analysis of the electronic structure, taking into\naccount the inter-atomic exchange interactions. The results confirm the\nexperimentally found partial phase separation, explain it as magnetic in\norigin, and indicate an additional metastable region connected with the\nferromagnetic transition in the system."
    },
    {
        "anchor": "Automated Reconstruction of Spherical Kikuchi Maps: An automated approach to reconstruct spherical Kikuchi maps from\nexperimentally collected electron backscatter diffraction patterns and overlay\neach pattern onto its corresponding position on a simulated Kikuchi sphere is\npresented in this study. This work demonstrates the feasibility of warping any\nKikuchi pattern onto its corresponding location of a simulated Kikuchi sphere\nand reconstructing a spherical Kikuchi map of a known phase based on any set of\nexperimental patterns. The proposed method is the first automated approach to\nreconstructing spherical Kikuchi maps from experimental Kikuchi patterns. It\npotentially enables more accurate orientation calculation, new pattern center\nrefinement methods, improved dictionary-based pattern matching, and phase\nidentification in the future.",
        "positive": "Coupling between Antiferromagnetic and Spin Glass Orders in the\n  Quasi-One-Dimensional Iron Telluride TaFe$_{1+x}$Te$_3$ ($x$=0.25): Understanding the interplay among different magnetic exchange interactions\nand its physical consequences, especially in the presence of itinerant\nelectrons and disorders, remains one of the central themes in condensed matter\nphysics. In this vein, the coupling between antiferromagnetic and spin glass\norders may lead to large exchange bias, a property of potential broad\ntechnological applications. In this article, we report the coexistence of\nantiferromagnetic order and spin glass behaviors in a quasi-one-dimensional\niron telluride TaFe$_{1+x}$Te$_3$ ($x$=0.25). Its antiferromagnetism is\nbelieved to arise from the antiferromagnetic interchain coupling between the\nferromagnetically aligned FeTe chains along the $b$-axis, while the spin glassy\nstate stems from the disordered Fe interstitials. This dichotomic role of chain\nand interstitial sublattices is responsible for the large exchange bias\nobserved at low temperatures, with the interstitial Fe acting as the\nuncompensated moment and its neighboring Fe chain providing the source for its\npinning. This iron-based telluride may thereby represent a new paradigm to\nstudy the large family of transition metal chalcogenides whose magnetic order\nor even the dimensionality can be tuned to a large extent, forming a fertile\nplayground to manipulate or switch the spin degrees of freedom thereof."
    },
    {
        "anchor": "Giant electrode effect on tunneling magnetoresistance and\n  electroresistance in van der Waals intrinsic multiferroic tunnel junctions: Van der Waals multiferroic tunnel junctions (vdW-MFTJs) with multiple\nnonvolatile resistive states are highly suitable for new physics and\nnext-generation storage electronics. However, currently reported vdW-MFTJs are\nbased on two types of materials, i.e., vdW ferromagnetic and ferroelectric\nmaterials, forming a multiferroic system. This undoubtedly introduces\nadditional interfaces, increasing the complexity of experimental preparation.\nHerein, we engineer vdW intrinsic MFTJs utilizing bilayer VS$_2$. By employing\nthe nonequilibrium Green's function combined with density functional theory, we\nsystematically investigate the influence of three types of electrodes\n(including non-vdW pure metal Ag/Au, vdW metallic 1T-MoS$_2$/2H-PtTe$_2$, and\nvdW ferromagnetic metallic Fe$_3$GaTe$_2$/Fe$_3$GeTe$_2$) on the electronic\ntransport properties of VS$_2$-based intrinsic MFTJs. We demonstrate that these\nMFTJs manifest a giant electrode-dependent electronic transport characteristic\neffect. Comprehensively comparing these electrode pairs, the\nFe$_3$GaTe$_2$/Fe$_3$GeTe$_2$ electrode combination exhibits optimal transport\nproperties, the maximum TMR (TER) can reach 10949\\% (69\\%) and the minimum\nresistance-area product (RA) is 0.45 $\\Omega$$\\mu$m$^{2}$, as well as the\nperfect spin filtering and negative differential resistance effects. More\nintriguingly, TMR (TER) can be further enhanced to 34000\\% (380\\%) by applying\nan external bias voltage (0.1 V), while RA can be reduced to 0.16\n$\\Omega$$\\mu$m$^{2}$ under the influence of biaxial stress (-3\\%). Our proposed\nconcept of designing vdW-MFTJs using intrinsic multiferroic materials points\ntowards new avenues in experimental exploration.",
        "positive": "Spectroscopic Studies of the Vibrational and Electronic Properties of\n  Solid Hydrogen to 285 GPa: We report Raman scattering and visible to near-infrared absorption spectra of\nsolid hydrogen under static pressure up to 285 GPa at 85-140 K. We obtain\npressure dependences of vibron and phonon modes in agreement with previously\ndetermined to lower pressures. The results indicate the stability of the\nordered molecular phase III to the highest pressure reached and provide\nconstraints on the insulator-to-metal transition pressure."
    },
    {
        "anchor": "Specific features of the luminescence and conductivity of zinc selenide\n  on exposure to X-ray and optical excitation: The set of experimental data on the X-ray-excited luminescence and X-ray\ninduced conductivity of ZnSe are compared to the data on the photoluminescence\nand photoconductivity. It is experimentally established that the\ncurrent-voltage characteristics and the kinetics of phosphorescence and current\nrelaxation depend on the type of excitation. It is found that the external\nelectric field influences the intensity and shape of bands in the luminescence\nspectra. It is shown that the character of excitation defines the kinetics of\nrecombination, charge carrier trapping, and conductivity in wide-gap\nsemiconductors.",
        "positive": "Symmetry-adapted modeling for molecules and crystals: We have developed a symmetry-adapted modeling procedure for molecules and\ncrystals. By using the completeness of multipoles to express spatial and\ntime-reversal parity-specific anisotropic distributions, we can generate\nsystematically the complete symmetry-adapted multipole basis set to describe\nany of electronic degrees of freedom in isolated cluster systems and periodic\ncrystals. The symmetry-adapted modeling is then achieved by expressing the\nHamiltonian in terms of the linear combination of these bases belonging to the\nidentity irreducible representation, and the model parameters (linear\ncoefficients) in the Hamiltonian can be determined so as to reproduce the\nelectronic structures given by the density-functional computation. We\ndemonstrate our method for the modeling of graphene, and emphasize usefulness\nof the symmetry-adapted basis to analyze and predict physical phenomena and\nspontaneous symmetry breaking in a phase transition. The present method is\ncomplementary to de-facto standard Wannier tight-binding modeling, and it\nprovides us with a fundamental basis to develop a symmetry-based analysis for\nmaterials science."
    },
    {
        "anchor": "Simulation of NMR Fermi contact shifts for Lithium battery materials:\n  the need of an efficient hybrid functional approach: In the context of the development of NMR Fermi contact shift calculations for\nassisting structural characterization of battery materials, we propose an\naccurate, efficient, and robust approach based on the use of an all electron\nmethod. The full-potential linearized augmented plane wave method, as\nimplemented in the WIEN2k code, is coupled with the use of hybrid functionals\nfor the evaluation of hyperfine field quantities. The WIEN2k code is able to\nfully relax relativistic core states and uses an autoadaptive basis set that is\nhighly accurate for the determination of the hyperfine field. Furthermore, the\nway hybrid functional approaches are implemented offers the possibility to use\nthem at no additional computational cost. In this paper, NMR Fermi contact\nshifts for lithium are studied in different classes of paramagnetic materials\nthat present an interest in the field of Li-ion batteries: olivine LiMPO4 (M =\nMn, Fe, Co, Ni), anti-NASICON type Li3M2(PO4)3 (M = Fe, V), and\nantifluorite-type Li6CoO4. Making use of the possibility to apply partial\nhybrid functionals either only on the magnetic atom or also on the anionic\nspecies, we evidence the role played by oxygen atoms on polarisation\nmechanisms. Our method is quite general for an application on various types of\nmaterials.",
        "positive": "Toward Mass-Production of Transition Metal Dichalcogenide Solar Cells:\n  Scalable Growth of Photovoltaic-Grade Multilayer WSe2 by Tungsten\n  Selenization: Semiconducting transition metal dichalcogenides (TMDs) are promising for\nhigh-specific-power photovoltaics due to desirable band gaps, high absorption\ncoefficients, and ideally dangling-bond-free surfaces. Despite their potential,\nthe majority of TMD solar cells are fabricated in a non-scalable fashion using\nexfoliated materials due to the absence of high-quality, large-area, multilayer\nTMDs. Here, we present the scalable, thickness-tunable synthesis of multilayer\ntungsten diselenide (WSe$_{2}$) films by selenizing pre-patterned tungsten with\neither solid source selenium or H$_{2}$Se precursors, which leads to smooth,\nwafer-scale WSe$_{2}$ films with a layered van der Waals structure. The films\nhave charge carrier lifetimes up to 144 ns, over 14x higher than large-area TMD\nfilms previously demonstrated. Such high carrier lifetimes correspond to power\nconversion efficiency of ~22% and specific power of ~64 W g$^{-1}$ in a\npackaged solar cell, or ~3 W g$^{-1}$ in a fully-packaged solar module. This\npaves the way for the mass-production of high-efficiency multilayer WSe$_{2}$\nsolar cells at low cost."
    },
    {
        "anchor": "Defect emission and its dipole orientation in layered ternary Znln2S4\n  semiconductor: Defect engineering is promising to tailor the physical properties of\ntwo-dimensional (2D) semiconductors for function-oriented electronics and\noptoelectronics. Compared with the extensively studied 2D binary materials, the\norigin of defects and their influence on physical properties of 2D ternary\nsemiconductors have not been clarified. In this work, we thoroughly studied the\neffect of defects on the electronic structure and optical properties of\nfew-layer hexagonal Znln2S4 via versatile spectroscopic tools in combination\nwith theoretical calculations. It has been demonstrated that the Zn-In\nanti-structural defects induce the formation of a series of donor and acceptor\nlevels inside the bandgap, leading to rich recombination paths for defect\nemission and extrinsic absorption. Impressively, the emission of donor-acceptor\npair (DAP) in Znln2S4 can be significantly tailored by electrostatic gating due\nto efficient tunability of Fermi level (Ef). Furthermore, the layer-dependent\ndipole orientation of defect emission in Znln2S4 was directly revealed by back\nfocal plane (BFP) imagining, where it presents obviously in-plane dipole\norientation within a dozen layers thickness of Znln2S4. These unique features\nof defects in Znln2S4 including extrinsic absorption, rich recombination paths,\ngate tunability and in-plane dipole orientation will definitely benefit to the\nadvanced orientation-functional optoelectronic applications.",
        "positive": "Magnetobreakdown oscillations of Nernst-Ettingshausen field in layered\n  conductors: In the presented report, the Nernst-Ettingshausen effect in layered\nconductors is investigated. Considering a Fermi surface (FS) consisting of a\nslightly corrugated cylinder and two corrugated planes distributed periodically\nin the momentum space, the thermoelectric effects are considered under general\nassumptions for the value of a magnetic breakdown probability. As a result of\nan external generalized force, the FS sheets in layered conductors with a\nmultisheet FS appear to be so close that the charge carriers (as a result of\nmagnetic breakdown) can move from one FS sheet to another. In addition, the\ndistribution functions of the charge carriers and the magnetic breakdown\noscillations of thermoelectrical field along the normal to the layer, under\ndifferent values and orientations of the magnetic field, $B$, are calculated.\nIt is shown that if the magnetic field is deflected from the $xz$-plane at an\nangle $\\varphi$, the oscillation part of a thermoelectrical field along the\nnormal to the layer under condition $\\sin\\varphi\\tan\\vartheta \\gg 1$ is mainly\ndetermined with the Nernst-Ettingshausen effect."
    },
    {
        "anchor": "Structural, morphological, and magnetic characterizations of\n  (Fe0.25Mn0.75)2O3 nanocrystals: a comprehensive stoichiometric determination: Iron manganese trioxide (Fe0.25Mn0.75)2O3 nanocrystals were synthesized by\nthe sol-gel method. The 80 K Mossbauer spectrum was well-fitted using two\ndoublets representing the 8b and 24d crystallographic sites of the\n(FexMn1-x)2O3 phase and two weak extra sextets which were attributed to\ncrystalline and amorphous hematite. Our findings showed formation of a bixbyite\nprimary phase. The Raman spectrum exhibits six Raman active modes, typical of\n(Fe,Mn)2O3, and two extra Raman modes associated with the secondary hematite\nphase. X-ray photoelectron spectroscopy analysis confirmed the presence of\noxygen vacancy onto the (FexMn1-x)2O3 particle surface, with varying oxidation\nstates. X-band magnetic resonance data revealed a single broad resonance line\nin the whole temperature range (3.8 K - 300 K). The temperature dependence of\nboth resonance field and resonance linewidth shows a remarkable change in the\nrange of 40 - 50 K, herein credited to surface spin glass behavior. The model\npicture used assumes (FexMn1-x)2O3 nanoparticles with a core-shell structure.\nResults indicate that below about 50 K the spin system of shell reveals a\nparamagnetic to spin glass-like transition upon cooling, with a critical\ntemperature estimated at 43 K. In the higher temperature range, the\nsuperparamagnetic hematite (secondary) phase contributes remarkably to the\ntemperature dependence of the resonance linewidth. Zero-field-cooled (ZFC) and\nfieldcooled (FC) data show strong irreversibility and a peak in the ZFC curve\nat 33 K, attributed to a paramagnetic-ferrimagnetic transition of the main\nphase. Hysteresis curve at 5 K shows a low coercive field of 4 kOe, with the\nmagnetization not reaching saturation at 70 kOe, suggesting the occurrence of a\nferrimagnetic core with a magnetic disorder at surface, characteristic of\ncore-shell spin-glass-like behavior.",
        "positive": "Ultrafast Dynamics of Electron-phonon Coupling in Transition-metal\n  Dichalcogenides: Time-domain femtosecond laser spectroscopic measurements of the ultrafast\nlattice dynamics in 2H-MoTe2 bulk crystals were carried out to understand the\ncarrier-phonon interactions that govern electronic transport properties. An\nunusually long lifetime coherent A1g phonon mode was observed even in the\npresence of very large density of photo-excited carriers at room temperature.\nThe decay rate was observed to decrease with increasing excitation laser\nfluence. Based on the laser fluence dependence including the inducement of\nsignificant phonon softening and a peculiar decrease in phonon decay rate, we\nattribute the long lifetime lattice dynamics to weak anharmonic phonon-phonon\ncoupling and a carrier-density-dependent deformation potential electron-phonon\ncoupling."
    },
    {
        "anchor": "How sandpiles spill: Sandpile problem in a thick flow regime: We obtain an analytical solution of a one-dimensional sandpile problem in a\nthick flow regime, when it can be formulated in terms of linear equations. It\nis shown that a space periodicity takes place during the sandpile evolution\neven for a sandpile of only one type of particles. Similar periodicity was\nobserved previo usly for many component sandpiles. Space periods are\nproportional to an input flow of particles $r_0$. We find that the surface\nangle $\\theta$ of the pile reaches it's final critical value ($\\theta_f$) from\nlower values only at long times. The deviation ($\\theta_f - \\theta$) behaves as\n$(t/r_{0})^{-1/2}$.",
        "positive": "Differences in Sb2Te3 growth by pulsed laser and sputter deposition: High quality Van der Waals chalcogenides are important for phase change data\nstorage, thermoelectrics, and spintronics. Using a combination of statistical\ndesign of experiments and density functional theory, we clarify how the\nout-of-equilibrium van der Waals epitaxial deposition methods can improve the\ncrystal quality of Sb2Te3 films. We compare films grown by radio frequency\nsputtering and pulsed laser deposition (PLD). The growth factors that influence\nthe crystal quality for each method are different. For PLD grown films a thin\namorphous Sb2Te3 seed layer most significantly influences the crystal quality.\nIn contrast, the crystalline quality of films grown by sputtering is rather\nsensitive to the deposition temperature and less affected by the presence of a\nseed layer. This difference is somewhat surprising as both methods are\nout-of-thermal-equilibrium plasma-based methods. Non-adiabatic quantum\nmolecular dynamics simulations show that this difference originates from the\ndensity of excited atoms in the plasma. The PLD plasma is more intense and with\nhigher energy than that used in sputtering, and this increases the electronic\ntemperature of the deposited atoms, which concomitantly increases the adatom\ndiffusion lengths in PLD. In contrast, the adatom diffusivity is dominated by\nthe thermal temperature for sputter grown films. These results explain the wide\nrange of Sb2Te3 and superlattice crystal qualities observed in the literature.\nThese results indicate that, contrary to popular belief, plasma-based\ndeposition methods are suitable for growing high quality crystalline\nchalcogenides."
    },
    {
        "anchor": "A Three-Dimensional Continuum Simulation Method for Grain Boundary\n  Motion Incorporating Dislocation Structure: We develop a continuum model for the dynamics of grain boundaries in three\ndimensions that incorporates the motion and reaction of the constituent\ndislocations. The continuum model is based on a simple representation of\ndensities of curved dislocations on the grain boundary. Illposedness due to\nnonconvexity of the total energy is fixed by a numerical treatment based on a\nprojection method that maintains the connectivity of the constituent\ndislocations. An efficient simulation method is developed, in which the\ncritical but computationally expensive long-range interaction of dislocations\nis replaced by another projection formulation that maintains the constraint of\nequilibrium of the dislocation structure described by the Frank's formula. This\ncontinuum model is able to describe the grain boundary motion and grain\nrotation due to both coupling and sliding effects, to which the classical\nmotion by mean curvature model does not apply. Comparisons with atomistic\nsimulation results show that our continuum model is able to give excellent\npredictions of evolutions of low angle grain boundaries and their dislocation\nstructures.",
        "positive": "Low frequency elastic wave propagation in 2D locally resonant phononic\n  crystal with asymmetric resonator: The resonance modes and the related effects to the transmission of elastic\nwaves in a two dimensional phononic crystal formed by periodic arrangements of\na two blocks unit cell in one direction are studied. The unit cell consists of\ntwo asymmetric elliptic cylinders coated with silicon rubber and embedded in a\nrigid matrix. The modes are obtained by the semi-analytic method in the least\nsquare collocation scheme and confirmed by the finite element method\nsimulations. Two resonance modes, corresponding to the vibration of the\ncylinder along the long and short axes, give rise to resonance reflections of\nelastic waves. One mode in between the two modes, related to the opposite\nvibration of the two cylinders in the unit cell in the direction along the\nlayer, results in the total transmission of elastic waves due to zero effective\nmass density at the frequency. The resonance frequency of this new mode changes\ncontinuously with the orientation angle of the elliptic resonator."
    },
    {
        "anchor": "High figure-of-merit in the heavy-fermion UN2 system for radioisotope\n  thermoelectric applications: The design of uranium-based thermoelectric materials presents a novel and\nintriguing strategy for directly converting nuclear heat into electrical power.\nUsing high-level first-principles approach combined with accurate solution of\nBoltzmann transport equation, we demonstrate that a giant n-type power factor\nof 13.8 mW/mK^2 and a peak ZT value of 2.2 can be realized in the heavy-fermion\nUN2 compound at 700 K. Such promising thermoelectric performance arises from\nthe large degeneracy (Nv=14) of heavy conduction band coupled with weak\nelectron-phonon interactions, which is in principle governed by the strong\nCoulomb correlation among the partially filled U-5f electrons in the\nface-centered cubic structure. Collectively, our theoretical work suggests that\nthe energetic UN2 is an excellent alternative to efficient radioisotope power\nconversion, which also uncovers an underexplored area for thermoelectric\nresearch.",
        "positive": "Potential mechanical loss mechanisms in bulk materials for future\n  gravitational wave detectors: Low mechanical loss materials are needed to further decrease thermal noise in\nupcoming gravitational wave detectors. We present an analysis of the\ncontribution of Akhieser and thermoelastic damping on the experimental results\nof resonant mechanical loss measurements. The combination of both processes\nallows the fit of the experimental data of quartz in the low temperature region\n(10 K to 25 K). A fully anisotropic numerical calculation over a wide\ntemperature range (10 K to 300 K) reveals, that thermoelastic damping is not a\ndominant noise source in bulk silicon samples. The anisotropic numerical\ncalculation is sucessfully applied to the estimate of thermoelastic noise of an\nadvanced LIGO sized silicon test mass."
    },
    {
        "anchor": "Comment on \"Reconciling results of tunnelling experiments on (Ga,Mn)As\"\n  arXiv:1102.3267v2 by Dietl and Sztenkiel: We comment on the recent paper \"Reconciling results of tunnelling experiments\non (Ga,Mn)As\" arXiv:1102.3267v2 by Dietl and Sztenkiel. They claimed that the\noscillations observed in the d2I/dV2-V characteristics in our studies on the\nresonant tunneling spectroscopy on GaMnAs, are not attributed to the resonant\nlevels in the GaMnAs layer but to the two-dimensional interfacial subbands in\nthe GaAs:Be layer. Here, we show that this interpretation is not able to\nexplain our experimental results and our conclusions remain unchanged.",
        "positive": "Strain-induced semiconductor to metal transition in MA2Z4 bilayers: Very recently, a new type of two-dimensional layered material MoSi2N4 has\nbeen fabricated, which is semiconducting with weak interlayer interaction, high\nstrength, and excellent stability. We systematically investigate theoretically\nthe effect of vertical strain on the electronic structure of MA2Z4 (M=Ti/Cr/Mo,\nA=Si, Z=N/P) bilayers. Taking bilayer MoSi2N4 as an example, our first\nprinciple calculations show that its indirect band gap decreases monotonically\nas the vertical compressive strain increases. Under a critical strain around\n22%, it undergoes a transition from semiconductor to metal. We attribute this\nto the opposite energy shift of states in different layers, which originates\nfrom the built-in electric field induced by the asymmetric charge transfer\nbetween two inner sublayers near the interface. Similar semiconductor to metal\ntransitions are observed in other strained MA2Z4 bilayers, and the estimated\ncritical pressures to realize such transitions are within the same order as\nsemiconducting transition metal dichalcogenides. The semiconductor to metal\ntransitions observed in the family of MA2Z4 bilayers present interesting\npossibilities for strain-induced engineering of their electronic properties."
    },
    {
        "anchor": "First 17O NMR study of a 17O enriched LaMnO3 stoichiometric crystal: We present the synthesis and the NMR characterization of a 17O enriched\nLaMnO3 crystalline sample. We checked that it is single phase and, more\nimportant, stochiometric in oxygen. Its 17O enrichment estimated by NMR is\nabout 5.5%. These first 17O NMR results obtained at T=415K in a undoped parent\nLaMnO3 manganite demonstrate that the two oxygen sites of the structure probe\nvery different Mn spin correlations in the paramagnetic orbital ordered phase.\nThis work opens the way to study experimentally the interactions responsible\nfor the orbital order.",
        "positive": "The Dirac-Weyl semimetal: Coexistence of Dirac and Weyl fermions in\n  polar hexagonal $ABC$ crystals: We propose that the noncentrosymmetric LiGaGe-type hexagonal $ABC$ crystal\nSrHgPb realizes a new type of topological semimetal that hosts both Dirac and\nWeyl points in momentum space. The symmetry-protected Dirac points arise due to\na band inversion and are located on the sixfold rotation $z$-axis, whereas the\nsix pairs of Weyl points related by sixfold symmetry are located on the\nperpendicular $k_z=0$ plane. By studying the electronic structure as a function\nof the buckling of the HgPb layer, which is the origin of inversion symmetry\nbreaking, we establish that the coexistence of Dirac and Weyl fermions defines\na phase separating two topologically distinct Dirac semimetals. These two Dirac\nsemimetals are distinguished by the $\\mathbb{Z}_2$ index of the $k_z=0$ plane\nand the corresponding presence or absence of 2D Dirac fermions on side\nsurfaces. We formalize our first-principles calculations by deriving and\nstudying a low-energy model Hamiltonian describing the Dirac-Weyl semimetal\nphase. We conclude by proposing several other materials in the\nnon-centrosymmetric $ABC $ material class, in particular SrHgSn and CaHgSn, as\ncandidates for realizing the Dirac-Weyl semimetal."
    },
    {
        "anchor": "Multiferroicity in Li0.05Ti0.02Ni0.93O Above Room Temperature: We present direct evidence of above room temperature magneto-electricity in\nsingle-phase Li0.05Ti0.02Ni0.93O with above-ambient antiferromagnetic ordering.\nTemperature-hysteresis in warming/cooling heat-flow thermograms establishes a\ndiscontinuous/first-order nature of the cubic-to-rhombohedral structural change\nconcurring the AFM transition. At TN = 488K, magnetization features a sharp\nslope-&-curvature discontinuity and dielectric constant shows a peak-anomaly.\nRoom temperature P-E loop measures a large polarization traceable to the N\\`eel\ndomain walls. We find positive room-temperature magneto-capacitance up to 9T,\nlinear at low-fields (MC ~ Hlow); the prefactor slope (dln{\\epsilon}'/dHlow)\nfeaturing a positive frequency-coefficient rises from O(10-3/T) at 0.1MHz to\nO(10-1/T) at 4MHz, with maximum d{\\epsilon}'/dH ~ 120/T.",
        "positive": "SmNiO3/NdNiO3 thin film multilayers: Rare earth nickelates RENiO3 which attract interest due to their sharp\nmetal-insulator phase transition, are instable in bulk form due to the\nnecessity of an important oxygen pressure to stabilize Ni in its 3+ state of\noxidation. Here, we report the stabilization of rare earth nickelates in\n[(SmNiO3)t/(NdNiO3)t]n thin film multilayers, t being the thickness of layers\nalternated n times. Both bilayers and multilayers have been deposited by\nMetal-Organic Chemical Vapour Deposition. The multilayer structure and the\npresence of the metastable phases SmNiO3 and NdNiO3 are evidenced from by X-ray\nand Raman scattering. Electric measurements of a bilayer structure further\nsupport the structural quality of the embedded rare earth nickelate layers."
    },
    {
        "anchor": "Data-driven compression of electron-phonon interactions: First-principles calculations of electron interactions in materials have seen\nrapid progress in recent years, with electron-phonon (e-ph) interactions being\na prime example. However, these techniques use large matrices encoding the\ninteractions on dense momentum grids, which reduces computational efficiency\nand obscures interpretability. For e-ph interactions, existing interpolation\ntechniques leverage locality in real space, but the high dimensionality of the\ndata remains a bottleneck to balance cost and accuracy. Here we show an\nefficient way to compress e-ph interactions based on singular value\ndecomposition (SVD), a widely used matrix / image compression technique.\nLeveraging (un)constrained SVD methods, we accurately predict material\nproperties related to e-ph interactions - including charge mobility, spin\nrelaxation times, band renormalization, and superconducting critical\ntemperature - while using only a small fraction (1-2%) of the interaction data.\nThese findings unveil the hidden low-dimensional nature of e-ph interactions.\nFurthermore, they accelerate state-of-the-art first-principles e-ph\ncalculations by about two orders of magnitudes without sacrificing accuracy.\nOur Pareto-optimal parametrization of e-ph interactions can be readily\ngeneralized to electron-electron and electron-defect interactions, as well as\nto other couplings, advancing quantitative studies of condensed matter.",
        "positive": "Magnetic Property of Rutile Ti0.94A0.06O2 (A=Li, Mg, K) Compounds: Our purpose is to study role of ionic radii of non-magnetic dopants; Li+\n(0.68 {\\AA}), Mg2+ (0.72 {\\AA}) and K+ (1.38 {\\AA}) on the magnetic property of\nrutile TiO2 compound. The Ti0.94A0.06O2 (A=Li, Mg, K) compounds have been\nsynthesized via solid state route method at equilibrium. The structural\nanalyses of X-ray diffraction pattern reveals that the doping of Li and Mg lead\nto Ti site substitution and K doping lead to core shell kind of structure. The\nmagnetic property measurement by SQUID magnetometer indicate that all compounds\nexhibit weak paramagnetism with highest paramagnetic moment of ~ 0.3 MuB / ion\nfor K doped compound but no long-range ferromagnetic ordering. We have\ndiscussed the observed magnetism in correlation with the nature of\nsubstitution."
    },
    {
        "anchor": "Two-domains bulklike Fermi surface of Ag films deposited onto\n  Si(111)-(7x7): Thick metallic silver films have been deposited onto Si(111)-(7x7) substrates\nat room temperature. Their electronic properties have been studied by using\nangle resolved photoelectron spectroscopy (ARPES). In addition to the\nelectronic band dispersion along the high-symmetry directions, the Fermi\nsurface topology of the grown films has been investigated. Using ARPES, the\nspectral weight distribution at the Fermi level throughout large portions of\nthe reciprocal space has been determined at particular perpendicular\nelectron-momentum values. Systematically, the contours of the Fermi surface of\nthese films reflected a sixfold symmetry instead of the threefold symmetry of\nAg single crystal. This loss of symmetry has been attributed to the fact that\nthese films appear to be composed by two sets of domains rotated 60$^o$ from\neach other. Extra, photoemission features at the Fermi level were also\ndetected, which have been attributed to the presence of surface states and\n\\textit{sp}-quantum states. The dimensionality of the Fermi surface of these\nfilms has been analyzed studying the dependence of the Fermi surface contours\nwith the incident photon energy. The behavior of these contours measured at\nparticular points along the Ag $\\Gamma$L high-symmetry direction puts forward\nthe three-dimensional character of the electronic structure of the films\ninvestigated.",
        "positive": "Tuning Elastic Properties of Metallic Nanoparticles by Shape\n  Controlling: From Atomistic to Continuous Models: Understanding and mastering the mechanical properties of metallic\nnanoparticles is crucial for their use in a wide range of applications. In this\ncontext, we use atomic-scale (Molecular Dynamics) and continuous (Finite\nElements) calculations to investigate in details gold nanoparticles under\ndeformation. By combining these two approaches, we show that the elastic\nproperties of such nanoobjects are driven by their size but, above all, by\ntheir shape. This outcome was achieved by introducing a descriptor in the\nanalysis of our results enabling to distinguish among the different\nnanoparticle shapes studied in the present work. In addition, other\ntransition-metal nanoparticles have been considered (copper and platinum) using\nthe aforementioned approach. The same strong dependence of the elastic\nproperties with the shape was revealed, thus highlighting the universal\ncharacter of our achievements."
    },
    {
        "anchor": "High-Performance Flexible Nanoscale Field-Effect Transistors Based on\n  Transition Metal Dichalcogenides: Two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs)\nare good candidates for high-performance flexible electronics. However, most\ndemonstrations of such flexible field-effect transistors (FETs) to date have\nbeen on the micron scale, not benefitting from the short-channel advantages of\n2D-TMDs. Here, we demonstrate flexible monolayer MoS2 FETs with the shortest\nchannels reported to date (down to 50 nm) and remarkably high on-current (up to\n470 uA/um at 1 V drain-to-source voltage) which is comparable to flexible\ngraphene or crystalline silicon FETs. This is achieved using a new transfer\nmethod wherein contacts are initially patterned on the rigid TMD growth\nsubstrate with nanoscale lithography, then coated with a polyimide (PI) film\nwhich becomes the flexible substrate after release, with the contacts and TMD.\nWe also apply this transfer process to other TMDs, reporting the first flexible\nFETs with MoSe2 and record on-current for flexible WSe2 FETs. These\nachievements push 2D semiconductors closer to a technology for low-power and\nhigh-performance flexible electronics.",
        "positive": "First Principles Study of Intrinsic and Extrinsic Point Defects in\n  Monolayer WSe2: We present a detailed first principles density functional theory study of\nintrinsic and extrinsic point defects in monolayer (ML) WSe2. Among the\nintrinsic point defects, Se vacancies (Sevac) have the lowest formation energy\n(disregarding Se adatoms that can be removed with annealing). The defects with\nthe next smallest formation energies (at least 1 eV larger) are SeW (Se\nsubstituting W atoms in an antisite defect), Wvac (W vacancies) and 2Sevac (Se\ndivacancies). All these intrinsic defects have gap states that are not\nspin-polarized. The presence of a graphite substrate does not change the\nformation energies of these defects significantly. For the extrinsic point\ndefects, we focus on O, O2, H, H2 and C interacting with perfect WSe2 and its\nintrinsic point defects. The preferred binding site in perfect WSe2 is the\ninterstitial site for atomic O, H and C. These interstitial defects have no gap\nstates. The gap states of the intrinsic defects are modified by interaction\nwith O, O2, H, H2 and C. In particular, the gap states of Sevac and 2Sevac are\ncompletely removed by interaction with O and O2. This is consistent with the\nsignificantly larger stability of O-related defects compared to H- and\nC-related defects. The preferred binding site for O is Sevac, while that for H\nis SeW. H bonded to SeW results in spin-polarized gap states, which may be\nuseful in defect engineering for spintronics applications. The charge\ntransition levels and ionization energies of these defects are also computed. H\nin the interstitial site is an effective donor, while all the other defects are\ndeep donors or acceptors in isolated WSe2 ML."
    },
    {
        "anchor": "Study of magnetism in MgO/FeCoB/MgO trilayers using x-ray standing wave\n  techniques: Interfaces in the MgO-FeCoB-MgO trilayer have been studied with grazing\nincident nuclear resonance scattering (GINRS) using the x-ray standing waves\n(XSW) technique. High depth selectivity of the present method allows one to\nmeasure magnetism and structure at the two interfaces of FeCoB, namely,\nFeCoB-on-MgO and MgO-on-FeCoB, independently, yielding an intriguing result\nthat both interfaces are not symmetric. A high-density layer with an increased\nmagnetic hyperfine field at the FeCoB-on-MgO interface suggests different\ngrowth mechanisms at the two interfaces. The azimuthal angle-dependent\nmagneto-optic Kerr effect measurements reveal the presence of unusual uniaxial\nmagnetic anisotropy (UMA) in the trilayer. An in-situ temperature-dependent\nstudy discovered that this UMA systematically reduces with temperature. The\ntrilayer becomes isotropic at 450C with an order-of-magnitude increase in\ncoercivity. The asymmetry at the interfaces is, in turn, explained by boron\ndiffusion from the FeCoB interface layer into the nearby MgO layer.\nStress-induced UMA is observed in the boron-deficient FeCoB layer, superimposed\nwith the bulk FeCoB layer, and found to be responsible for unusual UMA. The\ntemperature-dependent variation in the UMA and coercivity can be understood in\nterms of variations in the internal stresses and coupling between FeCoB bulk\nand the interface layer.",
        "positive": "Stimulated amplification of propagating spin waves: Spin-wave amplification techniques are key to the realization of magnon-based\ncomputing concepts. We introduce a novel mechanism to amplify spin waves in\nmagnonic nanostructures. Using the technique of rapid cooling, we create a\nnon-equilibrium state in excess of high-energy magnons and demonstrate the\nstimulated amplification of an externally seeded, propagating spin wave. Using\nan extended kinetic model, we qualitatively show that the amplification is\nmediated by an effective energy flux of high energy magnons into the low energy\npropagating mode, driven by a non-equilibrium magnon distribution."
    },
    {
        "anchor": "Cell-inspired, massive electromodulation of interfacial energy\n  dissipation: Transient electric fields across cell bilayer membranes can lead to\nelectroporation, as well as to cell fusion, and have been extensively studied.\nWe find that transmembrane electric fields similar to those in cells can lead\nto a massive, reversible modulation--by up to 200-fold--of the interfacial\nenergy dissipation between surfaces sliding across the lipid bilayer membranes.\nAtomistic simulations reveal that this arises from (fully reversible)\nelectroporation of the interfacially-confined bilayers, and formation of\nbilayer bridges analogous to stalks preceding intermembrane fusion. These\ncell-membrane-mimicking effects topologically-force the slip to\npartially-revert from the low-dissipation, hydrated lipid-headgroups plane to\nthe intra-bilayer, high-dissipation acyl tail interface. Our results\ndemonstrate that lipid bilayers under transmembrane electric fields can have\nstriking materials-modification properties, and shed new light on membrane\nhemifusion.",
        "positive": "Control of dopant crystallinity in electrochemically treated cuprate\n  thin films: We present a methodology based on \\textit{ex-situ} (post-growth)\nelectrochemistry to control the oxygen concentration in thin films of the\nsuperconducting oxide La$_2$CuO$_{4+y}$ grown epitaxially on substrates of\nisostructural LaSrAlO$_4$. The superconducting transition temperature, which\ndepends on the oxygen concentration, can be tuned by adjusting the pH level of\nthe base solution used for the electrochemical reaction. As our main finding,\nwe demonstrate that the dopant oxygens can either occupy the interstitial layer\nin an orientationally disordered state or organize into a crystalline phase via\na mechanism in which dopant oxygens are inserted into the substrate, changing\nthe lattice symmetry of both the substrate and the epitaxial film. We discuss\nthis mechanism, and describe the resulting methodology as a platform to be\nexplored in thin films of other transition metal oxides."
    },
    {
        "anchor": "Detection of Interlayer Interaction in Few-layer Graphene through Landau\n  Level Spectroscopy: We demonstrate that surface relaxation, which is insignificant in trilayer\ngraphene, starts to manifest in Bernal-stacked tetralayer graphene.\nBernal-stacked few-layer graphene has been investigated by analyzing its Landau\nlevel spectra through quantum capacitance measurements. We find that in\ntrilayer graphene, the interlayer interaction parameters were similar to that\nof graphite. However, in tetralayer graphene, the hopping parameters between\nthe bulk and surface bilayers are quite different. This shows a direct evidence\nfor the surface relaxation phenomena. In spite of the fact that the Van der\nWaals interaction between the carbon layers is thought to be insignificant, we\nsuggest that the interlayer interaction is an important factor in explaining\nthe observed results and the symmetry-breaking effects in graphene sublattice\nare not negligible.",
        "positive": "Experimental Determination of Electron Transition Probabilities in\n  Elementary Electron-Phonon Scattering Processes Using Electron-Energy-Loss\n  Spectroscopy: The Example of Graphite: We have investigated coupling constants in elementary electron-phonon\nscattering processes on a graphite surface by the combined use of\nhigh-resolution electron-energy-loss spectroscopy (HREELS) and very low-energy\nelectron diffraction (VLEED). HREELS is used to measure the modulations of\nelectron transition probabilities from incoming electrons in vacuum to outgoing\nelectrons in vacuum where the transition includes one-phonon scattering\nprocesses inside a solid. Determining the electronic band structures of\ngraphite with VLEED, we defined electronic states of the solid surface that\nelectrons entered before and after scattering off phonons. Thus, we observed\nthat the measured electron transition probabilities significantly depended on\nwhether the electrons were in a bulk Bloch state or an evanescent state before\nscattering off the phonons. This result clearly indicates that the measured\nelectron transition probabilities reflect the strength of the coupling\nconstants in the solid."
    },
    {
        "anchor": "A semi-empirical analysis of the paramagnetic susceptibility of solid\n  state magnetic clusters: Recent developments in the synthesis of new magnetic materials lead to the\ndiscovery of new quantum paramagnets. Many of these materials, such as the\nperovskites Ba$_{4}$LnMn$_{4}$O$_{12}$ (Ln = Sc or Nb),\nBa$_{3}$Mn$_{2}$O$_{8}$, and Sr$_{3}$Cr$_{2}$O$_{8}$ present isolated magnetic\nclusters with strong intracluster interactions but weak intercluster\ninteractions, which delays the onset of order to lower temperatures ($T$). This\noffset between the local energy scale and the magnetic ordering temperature is\nthe hallmark of magnetic frustration. At sufficient high-$T$, the paramagnetic\nsusceptibility ($\\chi$) of frustrated cluster magnets can be fit to a\nCurie-Weiss law, but the derived microscopic parameters cannot in general be\nreconciled with those obtained from other methods. In this work, we present an\nanalytical microscopic theory to obtain $\\chi$ of dimer and trimer cluster\nmagnets, the two most commonly found in literature, making use of suitable\nHeisenberg-type Hamiltonians. We also add intercluster interactions in a\nmean-field level, thus obtaining an expression to the critical temperature of\nthe system and defining a new effective frustration parameter $f_{\\text{eff}}$.\nOur method is exemplified by treating the $\\chi$ data of some selected\nmaterials.",
        "positive": "Molecular dynamics simulations of glassy polymers: We review recent results from computer simulation studies of polymer glasses,\nfrom chain dynamics around the glass transition temperature Tg to the\nmechanical behaviour below Tg. These results clearly show that modern computer\nsimulations are able to address and give clear answers to some important issues\nin the field, in spite of the obvious limitations in terms of length and time\nscales. In the present review we discuss the cooling rate effects, and dynamic\nslowing down of different relaxation processes when approaching Tg for both\nmodel and chemistry-specific polymer glasses. The impact of geometric\nconfinement on the glass transition is discussed in detail. We also show that\ncomputer simulations are very useful tools to study structure and mechanical\nresponse of glassy polymers. The influence of large deformations on mechanical\nbehaviour of polymer glasses in general, and strain hardening effect in\nparticular are reviewed. Finally, we suggest some directions for future\nresearch, which we believe will be soon within the capabilities of state of the\nart computer simulations, and correspond to problems of fundamental interest."
    },
    {
        "anchor": "Type-I and type-II Nodal Lines Coexistence in the Antiferromagnetic\n  monolayer CrAs$_{2}$: Topological nodal line semimetals, hosting one-dimensional Fermi lines with\nsymmetry protection, has become a hot topic in topological quantum matter. Due\nto the breaking of time reversal symmetry in magnetic system, nodal lines\nrequire protection by additional symmetries. Here, we report the discovery of\nantiferromagnetic type-I and type-II nodal lines coexist in the monolayer\nCrAs$_{2}$ based on a systematic first-principles calculation. Remarkably, the\ntype-I nodal line in CrAs$_{2}$ form a concentric loop centered around the\n$\\Gamma$ point is filling-enforced by nonsymmorphic analogue symmetry and\nrobust against spin-orbital coupling. The type-II nodal lines, a kind of open\nnodal lines appear around the Fermi level, are protected by the mirror symmetry\nin the absence of spin-orbital coupling. The antiferromagnetic monolayer\nCrAs$_{2}$ proposed here may provide a platform for the correlation between\nmagnetism and exotic topological phases.",
        "positive": "Ab initio calculations of the dynamical response of copper: The role of localized $d$-bands in the dynamical response of Cu is\ninvestigated, on the basis of {\\em ab initio} pseudopotential calculations. The\ndensity-response function is evaluated in both the random-phase approximation\n(RPA) and a time-dependent local-density functional approximation (TDLDA). Our\nresults indicate that in addition to providing a polarizable background which\nlowers the free-electron plasma frequency, d-electrons are responsible, at\nhigher energies and small momenta, for a double-peak structure in the dynamical\nstructure factor. These results are in agreement with the experimentally\ndetermined optical response of copper. We also analyze the dependence of\ndynamical scattering cross sections on the momentum transfer."
    },
    {
        "anchor": "In-situ high-pressure Raman scattering studies in PbWO4 up to 48 GPa: The effect of pressure on the Raman spectrum of PbWO4 has been investigated\nup to 48 GPa in a diamond-anvil cell using neon as pressure-transmitting\nmedium. Changes are detected in the Raman spectrum at 6.8 GPa as a consequence\nof a structural phase transition from the tetragonal scheelite structure to the\nmonoclinic PbWO4-III structure. Two additional phase transitions are detected\nat 15.5 and 21.2 GPa to the previously unknown crystalline phases IV and V. The\nlast one remains stable up to 43.3 GPa. At 47.7 GPa all Raman modes disappear,\nwhich could be caused by a pressure-induced amorphization. All structural\nchanges are reversible, being the scheelite phase recovered at ambient\npressure. However, the two most intense modes of the PbWO4-III phase are still\npresent after full decompression, indicating that this phase coexists as a\nminority metastable phase with the scheelite phase after pressure release. The\nwavenumber of the Raman modes and their pressure dependencies are reported for\nthe four crystalline phases. The present reported results are compared with\nprevious studies.",
        "positive": "Simple formalism for efficient derivatives and multi-determinant\n  expansions in quantum Monte Carlo: We present a simple and general formalism to compute efficiently the\nderivatives of a multi-determinant Jastrow-Slater wave function, the local\nenergy, the interatomic forces, and similar quantities needed in quantum Monte\nCarlo. Through a straightforward manipulation of matrices evaluated on the\noccupied and virtual orbitals, we obtain an efficiency equivalent to\nalgorithmic differentiation in the computation of the interatomic forces and\nthe optimization of the orbital paramaters. Furthermore, for a large\nmulti-determinant expansion, the significant computational gain recently\nreported for the calculation of the wave function is here improved and extended\nto all local properties in both all-electron and pseudopotential calculations."
    },
    {
        "anchor": "Spin-Filtering Multiferroic-Semiconductor Heterojunctions: We report on the structural and electronic properties of the interface\nbetween the multiferoic oxide YMnO$_3$ and wide band-gap semiconductor GaN\nstudied with the Hubbard-corrected local spin density approximation (LSDA+U) to\ndensity-functional theory (DFT). We find that the band offsets at the interface\nbetween antiferromagnetically ordered YMnO$_3$ and GaN are different for\nspin-up and spin-down states. This behavior is due to the spin splitting of the\nvalence band induced by the interface. The energy barrier depends on the\nrelative orientation of the electric polarization with respect to the\npolarization direction of the GaN substrate suggesting an opportunity to create\nmagnetic tunnel junctions in this materials system.",
        "positive": "Field-dependent low-field enhancement in effective paramagnetic moment\n  with nano-scaled Co3O4: Paramagnetic (PM) properties of columnar cobaltosic oxide (Co3O4)\nnanoparticles, about 75 nm in diameter, have been investigated by magnetization\nmeasurements at T > TN = 39 K. In zero or low applied field, the effective PM\nmoment per formula unit (FU), Mu_eff, enhances significantly from the bulk\nvalue of 4.14 Mu_B/FU. It decreases asymptotically from 5.96 Mu_B/FU at Happ =\n50 Oe down to 4.21 Mu_B/FU as the applied field increases to Happ = 10 kOe. The\nfield dependent PM properties are explained by a structural inversion, from the\nnormal spinel (spin-only moment ~ 3.9 Mu_B/FU) to the inverse spinel structure\n(spin-only moment ~ 8.8 Mu_B/FU). The structural inversion is reversible with\nthe variation of the applied field. The lattice structure becomes almost 100%\nnormal spinel in the high field exceeding 10 kOe, as revealed by the magnitude\nof the effective PM moment. The reversible, field dependent structure inversion\nis an important property with promising application potential. It is\ninteresting for the future investigations."
    },
    {
        "anchor": "Theoretical Modeling of Tribochemical Reaction on Pt and Au Contacts:\n  Mechanical Load and Catalysis: Micro-electro-mechanical system and nano-electro-mechanical system (MEMS and\nNEMS) transistors are considered promising for size-reducing and\npower-maximizing electronic devices. However, the tribopolymer which forms due\nto the mechanical load to the surface contacts affects the conductivity between\nthe contacts dramatically. This is one of the challenging problems that prevent\nwidespread practical use of these otherwise promising devices. Here, we use\ndensity functional theory (DFT) to investigate the mechanisms of tribopolymer\nformation, including normal mechanical loading, the catalytic effect, as well\nas the electrochemical effect of the metal contacts. We select benzene select\nas the background gas, because it is one of the most common and severe\nhydrocarbon contaminants. Two adsorption cases are considered: one is benzene\non the reactive metal surface, Pt(111), and the other is benzene on the noble\nmetal, Au(111). We demonstrate that the formation of tribopolymer is induced\nboth by the mechanical load and by the catalytic effect of the contact. First,\nbenzene molecules are adsorbed on the Pt surfaces. Then, due to the closure of\nthe Pt contacts, stress is applied to the adsorbates, making the C-H bonds more\nfragile. As the stress increases further, H atoms are pressed close to the Pt\nsubstrate and begin to bond with Pt atoms. Thus Pt acts as a catalyst,\naccelerating the dehydrogenation process. When there is voltage applied across\nthe contacts, the catalytic effect is enhanced by electrochemistry. Finally,\ndue to the loss of H atoms, C atoms become more reactive and link together or\npile up to form tribopolymer. By understanding these mechanisms, we provide\nguidance on design strategies for suppressing tribopolymer formation.",
        "positive": "Spin splitting and strain in epitaxial monolayer WSe$_2$ on graphene: We present the electronic and structural properties of monolayer WSe$_{2}$\ngrown by pulsed-laser deposition on monolayer graphene (MLG) on SiC. The spin\nsplitting in the WSe$_{2}$ valence band at $\\overline{\\mathrm{K}}$ was\n$\\Delta_\\mathrm{SO}=0.469\\pm0.008$ eV by angle-resolved photoemission\nspectroscopy (ARPES). Synchrotron-based grazing-incidence in-plane X-ray\ndiffraction (XRD) revealed the in-plane lattice constant of monolayer WSe$_{2}$\nto be $a_\\mathrm{WSe_2}=3.2757\\pm0.0008 \\mathrm{\\r{A}}$. This indicates a\nlattice compression of -0.19 % from bulk WSe$_{2}$. By using experimentally\ndetermined graphene lattice constant ($a_\\mathrm{MLG}=2.4575\\pm0.0007\n\\mathrm{\\r{A}}$), we found that a 3$\\times$3 unit cell of the slightly\ncompressed WSe$_{2}$ is perfectly commensurate with a 4$\\times$4 graphene\nlattice with a mismatch below 0.03 %, which could explain why the monolayer\nWSe$_{2}$ is compressed on MLG. From XRD and first-principles calculations,\nhowever, we conclude that the observed size of strain is negligibly small to\naccount for a discrepancy in $\\Delta_\\mathrm{SO}$ found between exfoliated and\nepitaxial monolayers in earlier ARPES. In addition, angle-resolved, ultraviolet\nand X-ray photoelectron spectroscopy shed light on the band alignment between\nWSe$_{2}$ and MLG/SiC and indicate electron transfer from graphene to the\nWSe$_{2}$ monolayer. As further revealed by atomic force microscopy, the\nWSe$_{2}$ island size depends on the number of carbon layers on top of the SiC\nsubstrate. This suggests that the epitaxy of WSe$_{2}$ favors the weak van der\nWaals interactions with graphene while it is perturbed by the influence of the\nSiC substrate and its carbon buffer layer."
    },
    {
        "anchor": "Atomic Insights into the Oxidative Degradation Mechanisms of Sulfide\n  Solid Electrolytes: Electrochemical degradation of solid electrolytes is a major roadblock in the\ndevelopment of solid-state batteries, and the formed solid-solid interphase\n(SSI) plays a key role in the performance of solid-state batteries. In this\nstudy, by combining experimental X-ray absorption spectroscopy (XAS)\nmeasurements, first-principles simulations, and unsupervised machine learning,\nwe have unraveled the atomic-scale oxidative degradation mechanisms of sulfide\nelectrolytes at the interface using the baseline Li3PS4 (LPS) electrolyte as a\nmodel system. The degradation begins with a decrease of Li neighbor affinity to\nS atoms upon initial delithiation, followed by the formation of S-S bonds as\nthe PS4 tetrahedron deforms. After the first delithiation cycle, the PS4 motifs\nbecome strongly distorted and PS3 motifs start to form. Spectral fingerprints\nof the local structural evolution are identified, which correspond to the main\npeak broadening and the peak shifting to a higher energy by about 2.5 eV in P\nK-edge XAS and a new peak emerging at 2473 eV in S K-edge XAS during\ndelithiation. The spectral fingerprints serve as a proxy for the\nelectrochemical stability of phosphorus sulfide solid electrolytes beyond LPS,\nas demonstrated in argyrodite Li6PS5Cl. We observed that the strong distortion\nand destruction of PS4 tetrahedra and the formation of S-S bonds are correlated\nwith an increased interfacial impedance. To the best of our knowledge, this\nstudy showcases the first atomic-scale insights into the oxidative degradation\nmechanism of the LPS electrolyte, which can provide guidance for controlling\nmacroscopic reactions through microstructural engineering and, more generally,\ncan advance the rational design of sulfide electrolytes.",
        "positive": "Theoretical specific heat, and thermal conductivity estimated by\n  detailed phonon vibrations: We report the calculation results of specific heat ($c_v$), and thermal\nconductivity ($\\kappa$) by using Einstein, and Debye models about rock salt\n(NaCl), oxides: Na$_x$CoO$_2$, SrTiO$_3$, and LiNbO$_3$. In calculation, the\nlongitudinal (L), and transverse (T) sound velocities ($v_T$, $v_L$) were\nestimated from acoustic phonons' dispersion's (~$\\omega$/$K$) in above\nmaterials, and the average sound velocities ($v_a$) were input into Debye model\nfor $\\kappa$ equation, and results were compared with that of Einstein model.\nIn some oxides, $v_a$ is relatively reduced at slight high $v_T$\n($v_T$/$v_L$=0.3-0.5). The relation of $\\kappa$, $v_a$ and $T$ were imaged as\nthe contour plots about realizing low $\\kappa$ values to be application of\nthermoelectric properties."
    },
    {
        "anchor": "Self-consistent Capacitance-Voltage Characterization of Gate-all-around\n  Graded Nanowire Transistor: This paper presents a self-consistent numerical model for calculating the\ncharge profile and gate capacitance and therefore obtaining C-V\ncharacterization for a gate-all-around graded nanowire MOSFET with a high\nmobility axially graded In0.75Ga0.25As + In0.53Ga0.47As channel incorporating\nstrain and atomic layer deposited Al2O3/20nm Ti gate. C-V characteristics with\nintroduction and variation of In-composition grading and also grading in doping\nconcentration are explored.Finite element method has been used to solve\nPoisson's equation and Schr\\\"odinger's equation self-consistently considering\nwave function penetration and other quantum effects to calculate gate\ncapacitance and charge profile for different gate biases. The device parameters\nare taken from a recently introduced experimental device.",
        "positive": "The memory kernel of the self-intermediate scattering function on a\n  MD-simulated glass-forming Ni$_{20}$Zr$_{80}$-system: The memory kernel of the self-part of the intermediate scattering function is\nstudied. We found that the short-time behavior of the memory kernel for our\nMD-simulated glass-forming Ni$_{20}$Zr$_{80}$-system shows a deviation from the\npolynomial form predicted by MCT. By using the gaussian approximation we give a\nmore detailed description of the short-time dynamics of the system."
    },
    {
        "anchor": "Spin-injection and spin-relaxation in p-doped InGaAs/GaAs quantum-dot\n  spin light emitting diode at zero magnetic field: We report on efficient spin injection in p-doped InGaAs/GaAs quantum-dot (QD)\nspin light emitting diode (spin-LED) under zero applied magnetic field. A high\ndegree of electroluminescence circular polarization (Pc) ~19% is measured in\nremanence up to 100K. This result is obtained thanks to the combination of a\nperpendicularly magnetized CoFeB/MgO spin injector allowing efficient spin\ninjection and an appropriate p-doped InGaAs/GaAs QD layer in the active region.\nBy analyzing the bias and temperature dependence of the electroluminescence\ncircular polarization, we have evidenced a two-step spin relaxation process.\nThe first step occurs when electrons tunnel through the MgO barrier and travel\nacross the GaAs depletion layer. The spin relaxation is dominated by the\nDyakonov-Perel mechanism related to the kinetic energy of electrons, which is\ncharacterized by a bias dependent Pc. The second step occurs when electrons are\ncaptured into QDs prior to their radiative recombination with holes. The\ntemperature dependence of Pc reflects the temperature induced modification of\nthe QDs doping, together with the variation of the ratio between the charge\ncarrier lifetime and the spin relaxation time inside the QDs. The understanding\nof these spin relaxation mechanisms is essential to improve the performance of\nspin LED for future spin optoelectronic applications at room temperature under\nzero applied magnetic field.",
        "positive": "Restoration of long range order of Na ions in $Na_xCoO_2$ at high\n  temperatures by sodium site doping: We have systematically investigated the $Na_xCoO_2$ system doped with Cu, Y,\nSn, W, Au and Bi for $x$ = 0:5; 0:75 and 1.00 using density functional theory.\nSn, W, and Bi always substitute a Co while Au always substitutes a Na\nregardless of Na concentration. However, for Cu and Y, the substitution site\ndepends on Na concentration. When compared to the available experimental data,\nwe find that thermoelectric performance is enhanced when the dopants substitute\na Na site. In this case, surprisingly, resistivity decreases despite the\nreduced hole concentration caused by carrier recombination. We propose improved\ncarrier mobility to be the cause of observed reduced resistivity."
    },
    {
        "anchor": "On the evolution of the non exchange spring behaviour to the exchange\n  spring behaviour: A First Order Reversal Curve Analysis: The magnetization behaviour of the soft Cobalt Ferrite-hard Strontium Ferrite\nnanocomposite is tuned from the non exchange spring nature to the exchange\nspring nature, by controlling the particle size of the soft Cobalt Ferrite in\nthe Cobalt Ferrite: Strontium Ferrite (1:8) nanocomposite. The relative\nstrength of the interaction governing the magnetization process in the\nnanocomposites is investigated using Henkel plot and First Order Reversal Curve\n(FORC) method. The FORC method has been utilized to understand the\nmagnetization reversal behaviour as well as the extent of the irreversible\nmagnetization present in both the nanocomposites having smaller and larger\nparticle size of the Cobalt Ferrite. The magnetization process is primarily\ncontrolled by the domain wall movement in the nanocomposites. Using the FORC\ndistribution in the (Ha, Hb) co-ordinate, the onset of the nucleation field,\ninvasion of the domain wall from the soft to the hard phase, domain wall\nannihilation and the presence of the reversible magnetization with the applied\nreversal field for both the nanocomposites has been investigated. It has been\nfound that for the composite having lower particle size of the soft phase shows\na single switching behaviour corresponding to the coherent reversal of the both\nsoft and hard phases. However, the composite having higher Cobalt Ferrite\nparticle size shows two peak behaviour in the FORC distribution resembling\nindividual switching of the soft and hard phases. The FORC distribution in (Hu,\nHc) co-ordinate and the Henkel measurement confirms the dominant exchange\ninteraction in the nanocomposites exhibiting exchange spring behaviour where as\nthe occurrence of both the dipolar and exchange interaction is substantiated\nfor the non exchange coupled nanocomposite.",
        "positive": "Parallel Self-Consistent-Field Calculations via Chebyshev-Filtered\n  Subspace Acceleration: Solving the Kohn-Sham eigenvalue problem constitutes the most computationally\nexpensive part in self-consistent density functional theory (DFT) calculations.\nIn a previous paper, we have proposed a nonlinear Chebyshev-filtered subspace\niteration method, which avoids computing explicit eigenvectors except at the\nfirst SCF iteration. The method may be viewed as an approach to solve the\noriginal nonlinear Kohn-Sham equation by a nonlinear subspace iteration\ntechnique, without emphasizing the intermediate linearized Kohn-Sham eigenvalue\nproblem. It reaches self-consistency within a similar number of SCF iterations\nas eigensolver-based approaches. However, replacing the standard\ndiagonalization at each SCF iteration by a Chebyshev subspace filtering step\nresults in a significant speedup over methods based on standard\ndiagonalization. Here, we discuss an approach for implementing this method in\nmulti-processor, parallel environment. Numerical results are presented to show\nthat the method enables to perform a class of highly challenging DFT\ncalculations that were not feasible before."
    },
    {
        "anchor": "A polarizable interatomic force field for TiO$_2$ parameterized using\n  density functional theory: We report a classical interatomic force field for TiO$_2$, which has been\nparameterized using density functional theory forces, energies, and stresses in\nthe rutile crystal structure. The reliability of this new classical potential\nis tested by evaluating the structural properties, equation of state, phonon\nproperties, thermal expansion, and some thermodynamic quantities such as\nentropy, free energy, and specific heat under constant volume. The good\nagreement of our results with {\\em ab initio} calculations and with\nexperimental data, indicates that our force-field describes the atomic\ninteractions of TiO$_2$ in the rutile structure very well. The force field can\nalso describe the structures of the brookite and anatase crystals with good\naccuracy.",
        "positive": "Evidence of liquid-liquid phase transition in compressed Ar probed by\n  the thermal expansion of Mo, Ta and W at high pressures: The long standing controversy between the melting curves of the bcc Mo,Ta,W\nand vanadium\n  (V) metals measured by diamond anvil Cells (DAC) and the shock dynamic\nexperiments is explained by the behavior the liquid or solid pressure\ntransmitting mediums compressed by the thermal expansion of the these\ntransition metals. This explains the observed isobaric behavior of the laser\nheated DAC experiments containing different transmitting mediums reported in\nthe literature, thus solving the standing enigma described in very many\npublications."
    },
    {
        "anchor": "The limitation for popular descriptions of alpha-relaxation temperature\n  dependence: Applicability of three popular functions (Vogel-Fulcher-Tammann, double\nactivation law and frustration-limited domains model) for the description of\nthe temperature dependence of alpha-relaxation time tau_alpha is considered for\nthree typical glass-formers (propylene carbonate, ethanol and picoline). Two\nfirst functions have three free parameters. It was found that while they are in\nsatisfactory agreement with the experimental data of tau_alpha(T), they fail in\ndescribing the transition from an Arrhenius-like to a non-Arrhenius behaviour.\nThis transition is seen in the derivative analysis of tau_alpha(T). We argue\nthat Vogel-Fulcher-Tammann and double activation functions should be applied\nand compared only at T < T_A, where T_A is the temperature of transition from\nan Arrhenius-like to a non-Arrhenius behaviour. It was shown that the\nfour-parametric frustration-limited domains model with imbedded transition from\nArrhenius to non-Arrhenius behaviour at T = T* also has no advantage in the\nderivative analysis, since T* is systematically different from TA in the cases\nconsidered.",
        "positive": "A Multiscale Constitutive Model for Metal Forming of Dual Phase Titanium\n  Alloys by Incorporating Inherent Deformation and Failure Mechanisms: Ductile metals undergo a considerable amount of plastic deformation before\nfailure. Void nucleation, growth and coalescence is the mechanism of failure in\nsuch metals. {\\alpha}/{\\beta} titanium alloys are ductile in nature and are\nwidely used for their unique set of properties like specific strength, fracture\ntoughness, corrosion resistance and resistance to fatigue failures. Voids in\nthese alloys were reported to nucleate on the phase boundaries between {\\alpha}\nand {\\beta} phase. Based on the findings of crystal plasticity finite element\nmethod (CPFEM) based investigation of the void growth at the interface of\n{\\alpha} and {\\beta} phases [1], [2], a void nucleation, growth, and\ncoalescence model has been formulated. An existing single-phase crystal\nplasticity theory is extended to incorporate underlying physical mechanisms of\ndeformation and failure in dual phase titanium alloys. Effects of various\nfactors (stress triaxiality, Lode parameter, deformation state (equivalent\nstrain), and phase boundary inclination) on void nucleation, growth and\ncoalescence are used to formulate the constitutive model while their\ninteraction with a conventional crystal plasticity theory is established. An\nextensive parametric assessment of the model is carried out to quantify and\nunderstand the effects of the material parameters on the overall material\nresponse. Performance of the proposed model is then assessed and verified by\ncomparing the results of the proposed model with the RVE study results.\nApplication of the constitutive model for utilisation in the design and\noptimisation of the forming process of {\\alpha}/{\\beta} titanium alloy\ncomponents is also demonstrated using experimental data."
    },
    {
        "anchor": "Additive manufacturing of Ni-Mn-Sn shape memory Heusler alloy --\n  Microstructure and magnetic properties from powder to printed parts: Ni-Mn-based Heusler alloys like Ni-Mn-Sn show an elastocaloric as well as\nmagnetocaloric effect during the magneto-structural phase transition, making\nthis material interesting for solid-state cooling application. Material\nprocessing by additive manufacturing can overcome difficulties related to\nmachinability of the alloys, caused by their intrinsic brittleness. Since the\nmagnetic properties and transition temperature are highly sensitive to the\nchemical composition, it is essential to understand and monitoring these\nproperties over the entire processing chain. In the present work the\nmicrostructural and magnetic properties from gas-atomized powder to\npost-processed Ni-Mn-Sn alloy are investigated. Direct energy deposition was\nused for processing, promoting the evolution of a polycrystalline\nmicrostructure being characterized by elongated grains along the building\ndirection. A complete and sharp martensitic transformation can be achieved\nafter applying a subsequent heat treatment at 1173 K for 24 h. The\nMn-evaporation of 1.3 at. % and the formation of Mn-oxide during DED-processing\nlead to an increase of the transition temperature of 45 K and a decrease of\nmagnetization, clearly pointing at the necessity of controlling the\ncomposition, oxygen partial pressure and magnetic properties over the entire\nprocessing chain.",
        "positive": "Lattice modelling of corrosion induced cracking and bond in reinforced\n  concrete: A lattice approach is used to describe the mechanical interaction of a\ncorroding reinforcement bar, the surrounding concrete and the interface between\nsteel reinforcement and concrete. The cross-section of the ribbed reinforcement\nbar is taken to be circular, assuming that the interaction of the ribs of the\ndeformed reinforcement bar and the surrounding concrete can be captured by a\ncap-plasticity interface model. The expansive corrosion process is represented\nby an Eigenstrain in the lattice elements forming the interface between\nconcrete and reinforcement. Several pull-out tests with varying degree of\ncorrosion are analysed. The numerical results are compared with experiments\nreported in the literature. The influence of the properties of concrete are\nstudied. The proposed lattice approach offers insight into corrosion induced\ncracking and its influence on bond strength."
    },
    {
        "anchor": "Ballistic bit addressing in a magnetic memory cell array: A ringing free bit addressing scheme for magnetic memories like MRAM\n(magnetic random access memory) is proposed. As in standard MRAM addressing\nschemes the switching of a selected cell is obtained by the combination of two\nhalf-select field pulses. Numerical solutions of a single spin model of an MRAM\ncell show that the pulse parameters can be chosen such that the application of\nthe half select pulse induces a full precessional turn of the magnetization (no\nswitch) whereas the superposition of two half select pulses induces a half\nprecessional turn (switch). With well adapted pulse parameters both fullselect\nand half-select switching occurs on ballistic trajectories characterized by the\nabsence of ringing after magnetic pulse decay. Such ballistic bit addressing\nallows ultra high MRAM clock rates. 1",
        "positive": "On the saturation stress of deformed metals: Crystalline materials exhibit an hysteresis behaviour when deformed\ncyclically. The origins of this tension-compression asymmetry have been fully\nunderstood only recently as being caused by an asymmetry in the junction\nstrength and a reduced mean free path of dislocations inherited from previous\ndeformation stage. Here, we investigate the saturation stress in fcc single-\nand poly-crystals using a Crystal Plasticity framework derived from dislocation\ndynamics simulations. In the absence of plastic localization and damage\nmechanism, the single-crystal mechanical response eventually saturates. We show\nthat the cyclic saturation stress converges asymptotically to the monotonic\nsaturation stress as the cycle plastic increment increases, and this\nconvergence can be observed for some experimental conditions. The analysis of\nthe experimental literature suggests that the mechanisms controlling the\nsaturation in single crystals are the same controlling the cyclic response of\npolycrystals with large grains. We propose also analytical and approximated\nmodels to predict the saturation stress over the considered loading conditions.\nThe saturation stress appears as a fundamental property of dislocations,\nexplaining the consistency observed in the experimental literature. This work\nprovides a unified view on the monotonous and cyclic responses of fcc single\nand poly-crystals, which may help in interpreting experimental data."
    },
    {
        "anchor": "LiMn1-xFexPO4 Nanorods Grown on Graphene Sheets for Ultra-High Rate\n  Performance Lithium Ion Batteries: Following the successful utilization of LiFePO4 as a novel cathode material\nfor rechargeable lithium batteries, interest and efforts have grown in the\nresearch of another olivine structured material LiMnPO4 due to its higher\noperating potential voltage and energy density. However, high rate performance\nfor LiMnPO4-based cathode materials has been challenging due to its extremely\nlow electrical and ionic conductivities. Here, we develop a synthesis of\nFe-doped LiMnPO4 (LiMn0.75Fe0.25PO4) nanorods directly bonded on graphene\nsheets (reduced from graphene oxide) to render LiMn0.75Fe0.25PO4 nanorods\nsuperior electrical conductivity. The LiMn0.75Fe0.25PO4 nanorod morphology is\nunique to materials grown on graphene over those grown in free solution, and is\nideal for fast Li+ diffusion with the diffusion path of [010] crystallographic\naxis along the short radial direction (~20-30nm) of the nanorods. These\ntogether lead to ultrafast discharge within ~30-40 seconds without using a high\ncarbon content. With high columbic efficiency above 99.5% at a high operating\nvoltage, our LiMn0.75Fe0.25PO4 nanorods/graphene hybrid exhibits the best rate\nperformance among all doped LiMnPO4 cathode materials for Lithium ion\nbatteries.",
        "positive": "Ab initio inversion of structure and the lattice dynamics of a metallic\n  glass: The case of Pd40Ni40P20: In this paper we infer the structure of Pd40Ni40P20 from experimental\ndiffraction data and ab initio interactions using Force Enhanced Atomic\nRefinement (FEAR). Our model accurately reproduces known experimental\nsignatures of the system and is more efficient than conventional melt-quench\nschemes. We critically evaluate the local order, carry out detailed comparisons\nto extended X-ray absorption fine structure (EXAFS) experiments and also\ndiscuss the electronic structure. We thoroughly explore the lattice dynamics of\nthe system, and describe a vibrational localized-to-extended transition and\ndiscuss the special role of P dynamics. At low energies P is fully contributing\nto extended modes, but at higher frequencies executes local motion reminiscent\nof a rattler inside a cage of metal atoms. These highly localized vibrational\nstates suggest a possible utility of these materials for thermoelectric\napplications."
    },
    {
        "anchor": "Modeling of Growth Morphology of Core-Shell Nanoparticles: We model shell formation of core-shell noble metal nanoparticles. A recently\ndeveloped kinetic Monte Carlo approach is utilized to reproduce growth\nmorphologies realized in recent experiments on core-shell nanoparticle\nsynthesis, which reported smooth epitaxially grown shells. Specifically, we\nidentify growth regimes that yield such smooth shells, but also those that lead\nto the formation of shells made of small clusters. The developed modeling\napproach allows us to qualitatively study the effects of temperature and supply\nthe shell-metal atoms on the resulting shell morphology, when grown on a\npre-synthesized nanocrystal core.",
        "positive": "Dimer Model for Electronic and Molecular Systems and the Intermediate\n  Phase: We introduce a lattice model of dimers with directional interactions as a\nparadigm of molecular fluids or strongly correlated Cooper pairs in electronic\nsystems. The model supports an intermediate phase that is common to both\nsystems. There are two different ideal glasses having no moblity since they\npossess zero entropy. A pairing parameter is introduced to study the\ngeometrical distribution of holes in various phases."
    },
    {
        "anchor": "Adsorption of Water on Fluorinated Graphene: In this paper, we investigate the adsorption of water monomer on fluorinated\ngraphene using state-of-the-art first principles methods within the framework\nof density functional theory (DFT). Four different methods are employed to\ndescribe the interactions between water and the carbon surface: The traditional\nDFT calculations within the generalized gradient approximation (GGA), and three\ntypes of calculations using respectively the semi-empirical DFT-D2method, the\noriginal van der Waals density functional (vdW-DF) method, and one of its\nvariants. Compared with the adsorption on pristine graphene, the adsorption\nenergies of water on fluorinated graphene are significantly increased, and the\norientations of water diploe moment are notably changed. The most stable\nconfiguration is found to stay right above the top site of the C atom which is\nbonded with F, and the dipole moment of water molecule aligns spontaneously\nalong the surface normal.",
        "positive": "Effects of Local Atomic Order on the Pre-Edge Structure in the Ti K\n  X-Ray Absorption Spectra of Perovskite CaTi1-xZrxO3: The effects of local B-cation (Ti, Zr) distribution and octahedral tilting on\nthe pre-edge structure in the Ti X-ray absorption K-spectra of the CaTi1-xZrxO3\nperovskite solid solutions were investigated. Experimental spectra for the\ndisordered CaTi1-xZrxO3 samples revealed systematic variations of the pre-edge\npeak intensities with the x-values. Multiple-scattering calculations using\n75-atom clusters Ti(TiO6)6-n(ZrO6)nCa8O24 were conducted to interpret these\ndifferences. The origin of the lowest unoccupied states in the conduction band\nof the CaTi1-xZrxO3 was determined from the analyses of X-ray absorption\nnear-edge structure of the O K-edge. The calculations reproduced the\nexperimental spectra and demonstrated that the differences in the intensities\nof certain pre-edge feature are dominated by the probability of finding a Zr\natom in the first B-cation coordination sphere around the absorbing Ti. The\npre-edge structure appeared to be sensitive to small changes in the value of\nthis probability, so that the pre-edge intensities could be used effectively to\ncompare the extent of local B-site order in perovskite solid solution samples\nhaving similar chemical composition but processed differently."
    },
    {
        "anchor": "Large non-reciprocal charge transport in Pt2MnGe up to room temperature: Non-reciprocal charge transport that is strongly associated with the\nstructural or magnetic chirality of the quantum materials system is one of the\nmost exotic properties of condensed matter physics. Here, using magnetic alloys\nfilm Pt2MnGe, we have realized the large non-reciprocal charge transport up to\nroom temperature, which roots in the organic combination of chirality dependent\ncarrier scattering and special magnetic configurations. In this framework, the\nconduction electrons are scattered asymmetrically by the emerging non-zero\nvector spin chirality under in-plane magnetic field, resulting in robust\nnon-reciprocal response. More astonishingly, the vector spin chirality in\nPt2MnGe film can be reversed by a spin-polarized current through spin Hall\neffect in a junction with Pt layer. Our work resolves the general limitation of\nnon-reciprocal charge transport to cryogenic temperatures, and paves the way\nfor extending its applications in the emerging field of chiral spintronics.",
        "positive": "Reply to Comment on \"Multiple locations of boron atoms in the exohedral\n  and endohedral C60 fullerene\" by J. Xu and G.-L. Hou: In three out of five cases considered in our work, DFT calculations presented\nby Xu and Hou in their Comment give the same ground state confirmations. On the\nother hand, depending on the choice of the exchange-correlation functional, the\ngeometry optimization within DFT results in different ground state\nconfirmations for B@C60 and B60, Table I of the Comment. Therefore, the energy\nbalance between nearest confirmations in these molecular complexes is subtle,\nand various methods can give different ground state structures. Consequently,\nthe results of our method - the Hartree-Fock (HF) approach with the second\norder M{\\o}ller-Plesset perturbation theory (MP2) - should be compared with the\nDFT results on equal ground, we cannot agree that the DFT method used in the\nComment is superior to HF-MP2. In the Reply, we also present additional HF\ncalculations with the 6-31G* basis set (used in the Comment for the geometry\noptimization) to show that the polarization functions do not change the ground\nstate confirmations obtained by us earlier at the HF/6-31G level."
    },
    {
        "anchor": "Diffusion of triplet excitons in an operational Organic Light Emitting\n  Diode: Measurements of the diffusion length L for triplet excitons in small\nmolecular-weight organic semiconductors are commonly carried out using a\ntechnique in which a phosphorescent-doped probe layer is set in the vicinity of\na supposed exciton generation zone. However, analyses commonly used to retrieve\n$L$ ignore microcavity effects that may induce a strong modulation of the\nemitted light as the position of the exciton probe is shifted. The present\npaper investigates in detail how this technique may be improved to obtain more\naccurate results for L. The example of 4,4'-bis(carbazol-9-yl)1,1'-biphenyl\n(CBP) is taken, for which a triplet diffusion length of L=16 +/- 4 nm (at 3\nmA/cm2) is inferred from experiments. The influence of triplet-triplet\nannihilation, responsible for an apparent decrease of L at high current\ndensities, is theoretically investigated, as well as the 'invasiveness' of the\nthin probe layer on the exciton distribution. The interplay of microcavity\neffects and direct recombinations is demonstrated experimentally with the\narchetypal trilayer structure\n[N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)]-4,4'-diaminobiphenyl (NPB)/CBP/\n2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (named bathocuproine, BCP). It is\nshown that in this device holes do cross the NPB/CBP junction, without the\nassistance of electrons and despite the high energetic barrier imposed by the\nshift between the HOMO levels. The use of the variable-thickness doped layer\ntechnique in this case is then discussed. Finally, some guidelines are given\nfor improving the measure of the diffusion length of triplet excitons in\noperational OLEDs, applicable to virtually any small molecular-weight material.",
        "positive": "A symmetry-derived mechanism for atomic resolution imaging: We introduce a new image contrast mechanism for scanning transmission\nelectron microscopy (STEM) that derives from the local symmetry within the\nspecimen. For a given position of the electron probe on the specimen, the image\nintensity is determined by the degree of similarity between the exit electron\nintensity distribution and a chosen symmetry operation applied to that\ndistribution. The contrast mechanism detects both light and heavy atomic\ncolumns and is robust with respect to specimen thickness, electron probe energy\nand defocus. Atomic columns appear as sharp peaks that can be significantly\nnarrower than for STEM images using conventional disc and annular detectors.\nThis fundamentally different contrast mechanism complements conventional\nimaging modes and can be acquired simultaneously with them, expanding the power\nof STEM for materials characterisation."
    },
    {
        "anchor": "The ferroelectric domain wall phonon polarizer: Modulating the polarization of a beam of quantum particles is a powerful\nmethod to tailor the macroscopic properties of the ensuing energy flux as it\ndirectly influences the way in which its quantum constituents interact with\nother particles, waves or continuum media. Practical polarizers, being well\ndeveloped for electric and electromagnetic energy, have not been proposed to\ndate for heat fluxes carried by phonons. Here we report on atomistic phonon\ntransport calculations demonstrating that ferroelectric domain walls can\noperate as phonon polarizers when a heat flux pierces them. Our simulations for\nrepresentative ferroelectric perovskite PbTiO$_3$ show that the structural\ninhomogeneity associated to the domain walls strongly suppresses transverse\nphonons, while longitudinally polarized modes can travel through multiple walls\nin series largely ignoring their presence.",
        "positive": "Bright and dark states of two distant macrospins strongly coupled by\n  phonons: We study the collective dynamics of two distant magnets coherently coupled by\nacoustic phonons that are transmitted through an intercalated crystal. By\ntuning the ferromagnetic resonances of the two magnets to an acoustic resonance\nof the crystal, we control a coherent three levels system. We show that the\nparity of the phonon mode governs the nature of the indirect coupling between\nthe magnets: the resonances with odd / even phonon modes correspond to\nout-of-phase / in-phase lattice displacements at the magnets, leading to bright\n/ dark states in response to uniform microwave magnetic fields, respectively.\nThe sample is a tri-layer garnet consisting of two thin magnetic layers\nepitaxially grown on both sides of a half-millimeter thick non-magnetic single\ncrystal. In spite of the relatively weak magneto-elastic interaction, the long\nlifetimes of the magnon and phonon modes in the sample are the key to unveil\nthis long range strong coupling. This demonstrates that garnets are a great\nplatform to study multi-partite hybridization process between magnon and\nphonons at microwave frequencies."
    },
    {
        "anchor": "Xe Irradiation of Graphene on Ir(111): From Trapping to Blistering: Using X-ray photoelectron spectroscopy, thermal desorption spectroscopy, and\nscanning tunneling microscopy we show that upon keV Xe + irradiation of\ngraphene on Ir(111), Xe atoms are trapped under the graphene. Upon annealing,\naggregation of Xe leads to graphene bulges and blisters. The efficient trapping\nis an unexpected and remarkable phenomenon, given the absence of chemical\nbinding of Xe to Ir and to graphene, the weak interaction of a perfect graphene\nlayer with Ir(111), as well as the substantial damage to graphene due to\nirradiation. By combining molecular dynamics simulations and density functional\ntheory calculations with our experiments, we uncover the mechanism of trapping.\nWe describe ways to avoid blister formation during graphene growth, and also\ndemonstrate how ion implantation can be used to intentionally create blisters\nwithout introducing damage to the graphene layer. Our approach may provide a\npathway to synthesize new materials at a substrate - 2D material interface or\nto enable confined reactions at high pressures and temperatures.",
        "positive": "Lifetimes of image-potential states on copper surfaces: The lifetime of image states, which represent a key quantity to probe the\ncoupling of surface electronic states with the solid substrate, have been\nrecently determined for quantum numbers $n\\le 6$ on Cu(100) by using\ntime-resolved two-photon photoemission in combination with the coherent\nexcitation of several states (U. H\\\"ofer et al, Science 277, 1480 (1997)). We\nhere report theoretical investigations of the lifetime of image states on\ncopper surfaces. We evaluate the lifetimes from the knowledge of the\nself-energy of the excited quasiparticle, which we compute within the GW\napproximation of many-body theory. Single-particle wave functions are obtained\nby solving the Schr\\\"odinger equation with a realistic one-dimensional model\npotential, and the screened interaction is evaluated in the random-phase\napproximation (RPA). Our results are in good agreement with the experimentally\ndetermined decay times."
    },
    {
        "anchor": "Spatiotemporal Mapping of Photocurrent in a Monolayer Semiconductor\n  Using a Diamond Quantum Sensor: The detection of photocurrents is central to understanding and harnessing the\ninteraction of light with matter. Although widely used, transport-based\ndetection averages over spatial distributions and can suffer from low\nphotocarrier collection efficiency. Here, we introduce a contact-free method to\nspatially resolve local photocurrent densities using a proximal quantum\nmagnetometer. We interface monolayer MoS2 with a near-surface ensemble of\nnitrogen-vacancy centers in diamond and map the generated photothermal current\ndistribution through its magnetic field profile. By synchronizing the\nphotoexcitation with dynamical decoupling of the sensor spin, we extend the\nsensor's quantum coherence and achieve sensitivities to alternating current\ndensities as small as 20 nA per micron. Our spatiotemporal measurements reveal\nthat the photocurrent circulates as vortices, manifesting the Nernst effect,\nand rises with a timescale indicative of the system's thermal properties. Our\nmethod establishes an unprecedented probe for optoelectronic phenomena, ideally\nsuited to the emerging class of two-dimensional materials, and stimulates\napplications towards large-area photodetectors and stick-on sources of magnetic\nfields for quantum control.",
        "positive": "Significant enhancement of room temperature ferromagnetism in surfactant\n  coated polycrystalline Mn doped ZnO particles: We report a surfactant assisted synthesis of Mn doped ZnO polycrystalline\nsamples showing robust room temperature ferromagnetism as characterized by\nX-ray diffraction analysis, Transmission Electron Microscopy, Electron\nParamagnetic Resonance and DC magnetization mearurements. This surfactant\nassisted synthesis method, developed by us, is found to be highly reproducible.\nFurther, it can also be extended to the synthesis of other transition metal\ndoped ZnO."
    },
    {
        "anchor": "Tunability of Magnetic Anisotropy of Co on Two-Dimensional Materials by\n  Tetrahedral Bonding: Pairing of $\\pi$ electronic state structures with functional or metallic\natoms makes them possible to engineer physical and chemical properties. Herein,\nwe predict the reorientation of magnetization of Co on hexagonal BN (h-BN) and\ngraphene multilayers. The driving mechanism is the formation of the tetrahedral\nbonding between sp$^3$ and d orbitals at the interface. More specifically, the\nintrinsic $\\pi$-bonding of h-BN and graphene is transformed to sp$^3$ as a\nresult of strong hybridization with metallic $d_{z^2}$ orbital. The different\nfeatures of these two tetrahedral bondings, sp$^2$ and sp$^3$, are well\nmanifested in charge density and density of states in the vicinity of the\ninterface, along with associated band structure near the $\\bar{K}$ valley. Our\nfindings provide a novel approach to tailoring magnetism by means of degree of\nthe interlayer hybrid bonds in 2D layered materials.",
        "positive": "Electronic structure study of double perovskites $A_{2}$FeReO$_{6}$\n  (A=Ba,Sr,Ca) and Sr$_{2}M$MoO$_{6}$ (M=Cr,Mn,Fe,Co) by LSDA and LSDA+U: We have implemented a systematic LSDA and LSDA+U study of the double\nperovskites $A_{2}$FeReO$_{6}$ (A=Ba,Sr,Ca) and Sr$_{2}$$M$MoO$_{6}$\n(M=Cr,Mn,Fe,Co) for understanding of their intriguing electronic and magnetic\nproperties. The results suggest a ferrimagnetic (FiM) and half-metallic (HM)\nstate of $A_{2}$FeReO$_{6}$ (A=Ba,Sr) due to a pdd-$\\pi$ coupling between the\ndown-spin Re$^{5+}$/Fe$^{3+}$ $t_{2g}$ orbitals via the intermediate O\n$2p_{\\pi}$ ones, also a very similar FiM and HM state of Sr$_{2}$FeMoO$_{6}$.\nIn contrast, a decreasing Fe $t_{2g}$ component at Fermi level ($E_{F}$) in the\ndistorted Ca$_{2}$FeReO$_{6}$ partly accounts for its nonmetallic behavior,\nwhile a finite $pdd$-$\\sigma$ coupling between the down-spin\nRe$^{5+}$/Fe$^{3+}$ $e_{g}$ orbitals being present at $E_{F}$ serves to\nstabilize its FiM state. For Sr$_{2}$CrMoO$_{6}$ compared with\nSr$_{2}$FeMoO$_{6}$, the coupling between the down-spin Mo$^{5+}$/Cr$^{3+}$\n$t_{2g}$ orbitals decreases as a noticeable shift up of the Cr$^{3+}$ 3d\nlevels, which is likely responsible for the decreasing $T_{C}$ value and weak\nconductivity. Moreover, the calculated level distributions indicate a\nMn$^{2+}$(Co$^{2+}$)/Mo$^{6+}$ ionic state in Sr$_{2}$MnMoO$_{6}$\n(Sr$_{2}$CoMoO$_{6}$), in terms of which their antiferromagnetic insulating\nground state can be interpreted. While orbital population analyses show that\nowing to strong intrinsic pd covalence effects, Sr$_{2}M$MoO$_{6}$\n(M=Cr,Mn,Fe,Co) have nearly the same valence state combinations, as accounts\nfor the similar M-independent spectral features observed in them."
    },
    {
        "anchor": "Freeze casting of hydroxyapatite scaffolds for bone tissue engineering: Although extensive efforts have been put into the development of porous\nscaffolds for bone regeneration, with encouraging results, all porous materials\nhave a common limitation: the inherent lack of strength associated with\nporosity. Hence, the development of porous hydroxyapatite scaffolds has been\nhindered to non-load bearing applications. We report here how freeze-casting\ncan be applied to synthesize porous hydroxyapatite scaffolds exhibiting\nunusually high compressive strength, e.g. up to 145 MPa for 47% porosity and 65\nMPa for 56% porosity. The materials are characterized by well-defined pore\nconnectivity along with directional and completely open porosity. Various\nparameters affecting the porosity and compressive strength have been\ninvestigated, including initial slurry concentration, freezing rate, and\nsintering conditions. The implications and potential application as bone\nsubstitute are discussed. These results might open the way for\nhydroxyapatite-based materials designed for load-bearing applications. The\nbiological response of these materials is yet to be tested.",
        "positive": "Stacking-fault energies for Ag, Cu, and Ni from empirical tight-binding\n  potentials: The intrinsic stacking-fault energies and free energies for Ag, Cu, and Ni\nare derived from molecular-dynamics simulations using the empirical\ntight-binding potentials of Cleri and Rosato [Phys. Rev. B 48, 22 (1993)].\nWhile the results show significant deviations from experimental data, the\ngeneral trend between the elements remains correct. This allows to use the\npotentials for qualitative comparisons between metals with high and low\nstacking-fault energies. Moreover, the effect of stacking faults on the local\nvibrational properties near the fault is examined. It turns out that the\nstacking fault has the strongest effect on modes in the center of the\ntransverse peak and its effect is localized in a region of approximately eight\nmonolayers around the defect."
    },
    {
        "anchor": "Periodic linear complexions: Co-segregation of solutes at a low-angle\n  grain boundary in a magnesium alloy: Solute segregation at low angle grain boundaries (LAGB) in Mg alloys\nsignificantly affects GB energy and mobility, therefore recrystallization\nkinetics and corresponding texture modification. In a system featuring multiple\nsubstitutional elements at high local concentration levels, solute-solute\ninteraction needs to be considered to interpret and predict co-segregation\nbehavior. In this work, atomic-scale experimental and modelling techniques were\napplied to investigate the co-segregation behavior of Ca, Zn and Al solutes at\na LAGB in a Mg alloy. Three-dimensional atom probe tomography and corresponding\nclustering analysis revealed a strong clustering tendency of Ca solutes at the\nlinear dislocation arrays. Atomistic simulations indicate that the\nco-segregation of Ca-Ca pairs in vicinity of the dislocation core region is\nmore energetically favorable than other solute pairs, as well as the\nsegregation of individual solutes.",
        "positive": "A new generalized Kohn-Sham method for fundamental band-gaps in solids: We developed a method for calculating solid-state ground-state properties and\nfundamental band-gaps using a generalized Kohn-Sham approach combining a local\ndensity approximation (LDA) functional with a long-range explicit exchange\norbital functional. We found that when the range parameter is selected\naccording to the formula \\gamma=A/(\\eps_\\inf - \\eps_\\tilde) where \\eps_\\inf is\nthe optical dielectric constant of the solid and \\eps_\\tilde= 0.84 and A=\n0.216a0^(-1), predictions of the fundamental band-gap close to the experimental\nvalues are obtained for a variety of solids of different types. For most solids\nthe range parameter \\gamma is small (i.e. explicit exchange is needed only at\nlong distances) so the predicted values for lattice constants and bulk modulii\nare similar to those based on conventional LDA calculations."
    },
    {
        "anchor": "Machine learning enabled experimental design and parameter estimation\n  for ultrafast spin dynamics: Advanced experimental measurements are crucial for driving theoretical\ndevelopments and unveiling novel phenomena in condensed matter and material\nphysics, which often suffer from the scarcity of facility resources and\nincreasing complexities. To address the limitations, we introduce a methodology\nthat combines machine learning with Bayesian optimal experimental design\n(BOED), exemplified with x-ray photon fluctuation spectroscopy (XPFS)\nmeasurements for spin fluctuations. Our method employs a neural network model\nfor large-scale spin dynamics simulations for precise distribution and utility\ncalculations in BOED. The capability of automatic differentiation from the\nneural network model is further leveraged for more robust and accurate\nparameter estimation. Our numerical benchmarks demonstrate the superior\nperformance of our method in guiding XPFS experiments, predicting model\nparameters, and yielding more informative measurements within limited\nexperimental time. Although focusing on XPFS and spin fluctuations, our method\ncan be adapted to other experiments, facilitating more efficient data\ncollection and accelerating scientific discoveries.",
        "positive": "Suppression of shear ionic motions in bismuth by coupling with\n  large-amplitude internal displacement: Bismuth, with its rhombohedral crystalline structure and two Raman active\nphonon modes corresponding to the internal displacement ($A_{1g}$) and shear\n($E_{g}$) ionic motions, offers an ideal target for the investigation of the\nphonon-phonon and electron-phonon couplings under photoexcitation. We perform\ntransient reflectivity measurements of bismuth single crystal at 11 K over wide\nrange of absorbed laser fluence up to $F_\\text{abs}=9$ mJ/cm$^2$, at which a\nsign of an irreversible surface damage is observed. At the minimum fluence\nexamined (0.1 mJ/cm$^2$) the coherent $A_{1g}$ and $E_g$ oscillations are a\ncosine and a sine functions of time, as are consistent with their generations\nin the displacive and impulsive limits, respectively. With increasing fluence\nthe initial phases of the both modes deviate from their low-fluence values,\nindicating a finite time required for the transition from the ground-state\npotential energy surface (PES) to the excited-state one. Surprisingly, the\n$E_g$ amplitude increases with increasing fluence up to 3 mJ/cm$^2$ and then\nturns to an apparent decrease, in contrast to the monotonic increase of the\n$A_{1g}$ amplitude up to 6 mJ/cm$^2$. The contrasted behaviors can be\nunderstood by considering a two-dimensional PES, where the strongly driven\n$A_{1g}$ oscillation leads to a temporal fluctuation of the PES along the $E_g$\ncoordinate and thereby to a loss in the $E_g$ oscillation coherence at high\nfluences."
    },
    {
        "anchor": "Graphene nanoribbons on vicinal SiC surfaces by molecular beam epitaxy: We present a new method of producing a densely ordered array of epitaxial\ngraphene nanoribbons (GNRs) using vicinal SiC surfaces as a template, which\nconsist of ordered pairs of (0001) terraces and nanofacets. Controlled\nselective growth of graphene on approximately 10 nm wide of (0001) terraces\nwith 10 nm spatial intervals allows GNR formation. By selecting the vicinal\ndirection of SiC substrate, [1-100], well-ordered GNRs with predominantly\narmchair edges are obtained. These structures, the high density GNRs, enable us\nto observe the electronic structure at K-points by angle-resolved photoemission\nspectroscopy, showing clear band-gap opening of at least 0.14 eV.",
        "positive": "The atomistic representation of first strain-gradient elastic tensors: We derive the atomistic representations of the elastic tensors appearing in\nthe linearized theory of first strain-gradient elasticity for an arbitrary\nmulti-lattice. In addition to the classical (2nd-Piola) stress and elastic\nmoduli tensors, these include the rank-three double-stress tensor, the\nrank-five tensor of mixed elastic moduli, and the rank-six tensor of\nstrain-gradient elastic moduli. The atomistic representations are closed-form\nanalytical expressions in terms of the first and second derivatives of the\ninteratomic potential with respect to interatomic distances, and dyadic\nproducts of relative atomic positions. Moreover, all expressions are local, in\nthe sense that they depend only on the atomic neighborhood of a lattice site.\nOur results emanate from the condition of energetic equivalence between\ncontinuum and atomistic representations of a crystal, when the kinematics of\nthe latter is governed by the Cauchy-Born rule. Using the derived expressions,\nwe prove that the odd-order tensors vanish if the lattice basis admits\ncentral-symmetry. The analytical expressions are implemented as a KIM compliant\nalgorithm to compute the strain gradient elastic tensors for various materials.\nNumerical results are presented to compare representative interatomic\npotentials used in the literature for cubic crystals, including simple lattices\nand multi-lattices. We observe that central potentials exhibit generalized\nCauchy relations for the rank-six tensor of strain-gradient elastic moduli. In\naddition, this tensor is found to be indefinite for many potentials. We discuss\nthe relationship between indefiniteness and material stability. Finally, the\natomistic representations are specialized to central potentials in simple\nlattices. These expressions are used with analytical potentials to study the\nsensitivity of the elastic tensors to the choice of the cutoff radius."
    },
    {
        "anchor": "The role of Hurst exponent on cold field electron emission from\n  conducting materials: from electric field distribution to Fowler-Nordheim\n  plots: This work considers the effects of the Hurst exponent ($H$) on the local\nelectric field distribution and the slope of the Fowler-Nordheim (FN) plot when\nconsidering the cold field electron emission properties of rough Large-Area\nConducting Field Emitter Surfaces (LACFESs). A LACFES is represented by a\nself-affine Weierstrass-Mandelbrot function in a given spatial direction. For\n$0.1 \\leqslant H < 0.5$, the local electric field distribution exhibits two\nclear exponential regimes. Moreover, a scaling between the macroscopic current\ndensity ($J_M$) and the characteristic kernel current density ($J_{kC}$),\n$J_{M} \\sim [J_{kC}]^{\\beta_{H}}$, with an H-dependent exponent $\\beta_{H} >\n1$, has been found. This feature, which is less pronounced (but not absent) in\nthe range where more smooth surfaces have been found ($0.5 \\leqslant H\n\\leqslant 0.9$), is a consequence of the dependency between the area efficiency\nof emission of a LACFES and the macroscopic electric field, which is often\nneglected in the interpretation of cold field electron emission experiments.\nConsidering the recent developments in orthodox field emission theory, we show\nthat the exponent $\\beta_{H}$ must be considered when calculating the slope\ncharacterization parameter (SCP) and thus provides a relevant method of more\nprecisely extracting the characteristic field enhancement factor from the slope\nof the FN plot.",
        "positive": "Synthesis, structure and magnetic properties of honeycomb-layered\n  Li3Co2SbO6 with new data on its sodium precursor, Na3Co2SbO6: Li3Co2SbO6 is prepared by molten salt ion exchange and its structure refined\nby the Rietveld method confirming the honeycomb-type Co/Sb ordering of its Na\nprecursor. Monoclinic rather than trigonal symmetry of Na3Co2SbO6 is directly\ndemonstrated for the first time by peak splitting in the high-resolution\nsynchrotron XRD pattern. The long-range antiferromagnetic order is established\nat TN about 6.7 K and 9.9 K in Na3Co2SbO6 and Li3Co2SbO6, respectively,\nconfirmed by both the magnetic susceptibility and specific heat. Spin-wave\nanalysis of specific heat data indicates the presence of 3D AFM magnons in\nNa3Co2SbO6 and 2D AFM magnons in Li3Co2SbO6. The field dependence of the\nmagnetization almost reaches saturation in moderate magnetic fields up to 9 T\nand demonstrates characteristic features of magnetic field induced\nspin-reorientation transitions for both A3Co2SbO6 (A = Na, Li). Overall\nthermodynamic studies show that the magnetic properties of both compounds are\nvery sensitive to an external magnetic field, thus predicting a non-trivial\nground state with a rich magnetic phase diagram. The ground state spin\nconfiguration of Li3Co2SbO6 has been determined by low-temperature neutron\npowder diffraction. It represents a ferromagnetic arrangement of moments in the\nhoneycomb layers with antiferromagnetic coupling between adjacent layers."
    },
    {
        "anchor": "Spin Seebeck effect in Y-type hexagonal ferrite thin films: Spin Seebeck effect (SSE) has been investigated in thin films of two\nY-hexagonal ferrites Ba$_2$Zn$_{2}$Fe$_{12}$O$_{22}$ (Zn2Y) and\nBa$_2$Co$_{2}$Fe$_{12}$O$_{22}$ (Co2Y) deposited by a spin-coating method on\nSrTiO$_3$(111) substrate. The selected hexagonal ferrites are both\nferrimagnetic with similar magnetic moments at room temperature and both\nexhibit easy magnetization plane normal to $c$-axis. Despite that, SSE signal\nwas only observed for Zn2Y, whereas no significant SSE signal was detected for\nCo2Y. We tentatively explain this different behavior by a presence of two\ndifferent magnetic ions in Co2Y, whose random distribution over octahedral\nsites interferes the long range ordering and enhances the Gilbert damping\nconstant. The temperature dependence of SSE for Zn2Y was measured and analyzed\nwith regard to the heat flux and temperature gradient relevant to the SSE\nsignal.",
        "positive": "Field-induced Bose-Einstein condensation of interacting dilute magnons\n  in three-dimensional spin systems: A renormalization-group study: We use the Renormalization Group method to study the magnetic field influence\non the Bose-Einstein condensation of interacting dilute magnons in three\ndimensional spin systems. We first considered a model with SU(2) symmetry\n(universality class $z=1$) and we obtain for the critical magnetic field a\npower law dependence on the critical temperature, $[H_c(T)-H_c(0)]\\sim T^2$. In\nthe case of U(1) symmetry (universality class $z=2$) the dependence is\ndifferent, and the magnetic critical field depends linearly on the critical\ntemperature, $[H_c(T)-H_c(0)]\\sim T$. By considering a more relevant model,\nwhich includes also the system's anisotropy, we obtain for the same symmetry\nclass a $T^{3/2}$ dependence of the magnetic critical field on the critical\ntemperature. We discuss these theoretical predictions of the renormalization\ngroup in connection with experimental results reported in the literature."
    },
    {
        "anchor": "Bandgap opening in metallic carbon nanotubes due to silicon impurities: Controlling the bandgap of carbon nanostructures is key to the development\nand mainstream application of carbon-based nanoelectronic devices. We report\ndensity functional theory calculations of the effect of silicon impurities on\nthe electronic properties of carbon nanotubes (CNTs). We have found that Si\nadatoms open up a bandgap in intrinsically metallic CNTs even when the linear\ndensity of Si atoms is low enough that they do not create a bonded adatom\nchain. The bandgap opened in metallic CNTs can range between 0.10 eV and 0.47\neV, depending on adsorption site, linear density of Si adatoms, and CNT\nchirality.",
        "positive": "AiiDA-defects: An automated and fully reproducible workflow for the\n  complete characterization of defect chemistry in functional materials: Functional materials that enable many technological applications in our\neveryday lives owe their unique properties to defects that are carefully\nengineered and incorporated into these materials during processing. However,\noptimizing and characterizing these defects is very challenging in practice,\nmaking computational modelling an indispensable complementary tool. We have\ndeveloped an automated workflow and code to accelerate these calculations\n(AiiDA-defects), which utilises the AiiDA framework, a robust open-source\nhigh-throughput materials informatics infrastructure that provides workflow\nautomation while simultaneously preserving and storing the full data provenance\nin a relational database that is queryable and traversable. This paper\ndescribes the design and implementation details of AiiDA-defects, the models\nand algorithms used, and demonstrates its use in an application to fully\ncharacterize the defect chemistry of the well known solid-state Li-ion\nconductors LiZnPS 4 . We anticipate that AiiDA-defects will be useful as a tool\nfor fully automated and reproducible defect calculations, allowing detailed\ndefect chemistry to be obtained in a reliable and high-throughput way, and\npaving the way toward the generation of defects databases for accelerated\nmaterials design and discovery"
    },
    {
        "anchor": "A short note on the SIMS characterisation of ZnO/Si(100) interface: The ZnO films, 25 nm thick were deposited by e-beam evaporation of ZnO\n(99.9%) pellets onto native oxide covered silicon (100) substrates. Details of\nthe interface chemical composition and the chemical depth profile have been\ndeduced as follows: Adsorbed OH surface/OH: ZnO Interface/Pure ZnO thin\nfilm/ZnO:H: Si Interface/H:SiO2/SiO2/Si(100). The physical profile of the\ncrater formed by the SIMS depth profiling was measured with a Tencor P-2\nprofilometer as depth profiling showed uniform ion milling and good consistency\nwith film thickness (25 nm) measured by SIMS depth profile (25.4 nm).",
        "positive": "Discovery of low thermal conductivity compounds with first-principles\n  anharmonic lattice dynamics calculations and Bayesian optimization: Compounds of low lattice thermal conductivity (LTC) are essential for seeking\nthermoelectric materials with high conversion efficiency. Some strategies have\nbeen used to decrease LTC. However, such trials have yielded successes only\nwithin a limited exploration space. Here we report the virtual screening of a\nlibrary containing 54,779 compounds. Our strategy is to search the library\nthrough Bayesian optimization using for the initial data the LTC obtained from\nfirst-principles anharmonic lattice dynamics calculations for a set of 101\ncompounds. We discovered 221 materials with very low LTC. Two of them have even\nan electronic band gap < 1 eV, what makes them exceptional candidates for\nthermoelectric applications. In addition to those newly discovered\nthermoelectric materials, the present strategy is believed to be powerful for\nmany other applications in which chemistry of materials are required to be\noptimized."
    },
    {
        "anchor": "A Generalized Read-Shockley Model and Large Scale Simulations for the\n  Energy and Structure of Graphene Grain Boundaries: The grain boundary (GB) energy is a quantity of fundamental importance for\nunderstanding several key properties of graphene. Here we present a\ncomprehensive theoretical and numerical study of the entire space of symmetric\nand asymmetric graphene GBs. We have simulated over 79,000 graphene GBs to\nexplore the configuration space of GBs in graphene. We use a generalized\nRead-Shockley theory and the Frank-Bilby relation to develop analytical\nexpressions for the GB energy as a function of the misorientation angle and the\nline angle, and elucidate the salient structural features of the low energy GB\nconfigurations.",
        "positive": "VO$_2$ as a natural optical metamaterial: VO$_2$ is a unique phase change material with strongly anisotropic electronic\nproperties. Recently, samples have been prepared that present a co-existence of\nphases and thus form metal-insulator junctions of the same chemical compound.\nUsing first principles calculations, the optical properties of metallic and\nsemiconducting VO$_2$ are here discussed to design self-contained natural\noptical metamaterials, avoiding coupling with other dielectric media. The\nanalysis of the optical properties complements the experiments in the\ndescription of the vast change in reflectance and metallicity for both\ndisordered and planar compounds. The present results also predict the\npossibility to realize ordered VO$_2$ junctions operating as efficient\nhyperbolic metamaterials in the THz-visible range, by simply adjusting the\nratio between metallic and insulating VO$_2$ content. The possibility to excite\npropagating {\\em volume plasmom polariton} across the metamaterial is finally\ndiscussed."
    },
    {
        "anchor": "Understanding of the Retarded Oxidation Effects in Silicon\n  Nanostructures: In-depth understanding of the retarded oxidation phenomenon observed during\nthe oxidation of silicon nanostructures is proposed. The wet thermal oxidation\nof various silicon nanostructures such as nanobeams, concave/convex nanorings\nand nanowires exhibits an extremely different and complex behavior. Such\neffects have been investigated by the modeling of the mechanical stress\ngenerated during the oxidation process explaining the retarded regime. The\nmodel describes the oxidation kinetics of silicon nanowires down to a few\nnanometers while predicting reasonable and physical stress levels at the\nSi/SiO$_{2}$ interface by correctly taking into account the relaxation effects\nin silicon oxide through plastic flow.",
        "positive": "TiN Films Deposited by Laser CVD: A Growth Kinetics Study: Results on the chemical composition, structure and growth kinetics of\ntitanium nitride (TiN) films deposited on mild steel substrates by pyrolytic\nlaser-induced chemical vapour deposition (LCVD) are presented. Golden coloured\nlines of TiN were deposited from a reactive gas mixture of TiCl4, N2 and H2\nusing a continuous wave TEM00 CO2 laser beam as heat source. The chemical\ncomposition and structure of the films were determined by electron probe\nmicroanalysis (EPMA) and glancing incidence X-ray diffraction (GIXRD). A\nnon-contact laser profilometer was used to measure the thickness profiles of\nthe films. Using the data obtained in the steady-state region of the TiN\nlaser-written lines, growth rates in the range 3.7 to 6.9 micrometers per\nsecond were deduced. The Arrhenius relation between the deposition rate and the\ndeposition temperature yields an apparent activation energy of 46.9(+-)3.8\nkJ.mol-1. This result enabled us to conclude that under our deposition\nconditions the LCVD of TiN is controlled by mass transport in the vapour phase.\n  Keywords: Coatings; Titanium nitride (TiN); Laser chemical vapour deposition\n(LCVD); Growth mechanisms."
    },
    {
        "anchor": "Finite-size versus Surface effects in nanoparticles: We study the finite-size and surface effects on the thermal and spatial\nbehaviors of the magnetisation of a small magnetic particle. We consider two\nsystems: 1) A box-shaped isotropic particle of simple cubic structure with\neither periodic or free boundary conditions. This case is treated analytically\nusing the isotropic model of D-component spin vectors in the limit $D\\to\n\\infty$, including the magnetic field. 2) A more realistic particle ($\\gamma\n$-Fe$_{2}$O$_{3}$) of ellipsoidal (or spherical) shape with open boundaries.\nThe magnetic state in this particle is described by the anisotropic classical\nDirac-Heisenberg model including exchange and dipolar interactions, and bulk\nand surface anisotropy. This case is dealt with by the classical Monte Carlo\ntechnique. It is shown that in both systems finite-size effects yield a\npositive contribution to the magnetisation while surface effects render a\nlarger and negative contribution, leading to a net decrease of the\nmagnetisation of the small particle with respect to the bulk system. In the\nsystem 2) the difference between the two contributions is enhanced by surface\nanisotropy. The latter also leads to non saturation of the magnetisation at low\ntemperatures, showing that the magnetic order in the core of the particle is\nperturbed by the magnetic disorder on the surface. This is confirmed by the\nprofile of the magnetisation.",
        "positive": "Planar Heterostructure Graphene -- Narrow-Gap Semiconductor -- Graphene: We investigate a planar heterostructure composed of two graphene films\nseparated by a narrow-gap semiconductor ribbon. We show that there is no the\nKlein paradox when the Dirac points of the Brillouin zone of graphene are in a\nband gap of a narrow-gap semiconductor. There is the energy range depending on\nan angle of incidence, in which the above-barrier damped solution exists.\nTherefore, this heterostructure is a \"filter\" transmitting particles in a\ncertain range of angles of incidence upon a potential barrier. We discuss the\npossibility of an application of this heterostructure as a \"switch\"."
    },
    {
        "anchor": "Controlled Fabrication of Metallic Electrodes with Atomic Separation: We report a new technique for fabricating metallic electrodes on insulating\nsubstrates with separations on the 1 nm scale. The fabrication technique, which\ncombines lithographic and electrochemical methods, provides atomic resolution\nwithout requiring sophisticated instrumentation. The process is simple,\ncontrollable, reversible, and robust, allowing rapid fabrication of electrode\npairs with high yield. We expect the method to prove useful in interfacing\nmolecular-scale structures to macroscopic probes and electronic devices .",
        "positive": "Stabilizing the forming process in unipolar resistance switching using\n  an improved compliance current limiter: The high reset current IR in unipolar resistance switching now poses major\nobstacles to practical applications in memory devices. In particular, the first\nIR-value after the forming process is so high that the capacitors sometimes do\nnot exhibit reliable unipolar resistance switching. We found that the\ncompliance current Icomp is a critical parameter for reducing IR-values. We\ntherefore introduced an improved, simple, easy to use Icomp-limiter that\nstabilizes the forming process by drastically decreasing current overflow, in\norder to precisely control the Icomp- and subsequent IR-values."
    },
    {
        "anchor": "Epitaxial thin films of multiferroic Bi2FeCrO6 with B-site cationic\n  order: Epitaxial thin films of Bi2FeCrO6 have been synthesized by pulsed laser\ndeposition on SrRuO3 on (100)- and (111)-oriented SrTiO3 substrates. Detailed\nX-ray diffraction and cross-section transmission electron microscopy analysis\nrevealed a double perovskite crystal structure of the Bi2FeCrO6 epitaxial films\nvery similar to that of BiFeO3 along with a particularly noteworthy Fe3+/Cr3+\ncation ordering along the [111] direction. The films contain no detectable\nmagnetic iron oxide impurities and have the correct cationic average\nstoichiometry throughout their thickness. They however exhibit a slight\nmodulation in the Fe and Cr compositions forming complementary stripe patterns,\nsuggesting minor local excess or depletion of Fe and Cr. The epitaxial BFCO\nfilms exhibit good ferroelectric and piezoelectric properties, in addition to\nmagnetic properties at room temperature, as well as an unexpected\ncrystallographic orientation dependence of their room temperature magnetic\nproperties. Our results qualitatively confirm the predictions made using the\nab-initio calculations: the double-perovskite structure of Bi2FeCrO6 films\nexhibit a Fe3+/Cr3+ cation ordering and good multiferroic properties, along\nwith the unpredicted existence of magnetic ordering at room temperature.",
        "positive": "Complex edge effects in zigzag graphene nanoribbons due to hydrogen\n  loading: We have performed density functional calculations as well as employed a\ntight-binding theory, to study the effect of passivation of zigzag graphene\nnanoribbons (ZGNR) by Hydrogen. We show that each edge C atom bonded with 2 H\natoms open up a gap and destroys magnetism for small widths of the nanoribbon.\nHowever, a re-entrant magnetism accompanied by a metallic electronic structure\nis observed from 8 rows and thicker nanoribbons. The electronic structure and\nmagnetic state are quite complex for this type of termination, with sp$^3$\nbonded edge atoms being non-magnetic, whereas the nearest neighboring atoms are\nmetallic and magnetic. We have also evaluated the phase stability of several\nthicknesses of ZGNR, and demonstrate that sp$^3$ bonded edge atoms, with 2 H\natoms at the edge, should be stable at temperatures and pressures which are\nreachable in a laboratory environment."
    },
    {
        "anchor": "Alloying effects on the optical properties of Ge$_{1-x}$Si$_x$\n  nanocrystals from TDDFT and comparison with effective-medium theory: We present the optical spectra of Ge$_{1-x}$Si$_x$ alloy nanocrystals\ncalculated with time-dependent density-functional theory in the adiabatic\nlocal-density ap proximation (TDLDA). The spectra change smoothly as a function\nof the compositio n $x$. On the Ge side of the composition range, the lowest\nexcitations at the ab sorption edge are almost pure Kohn-Sham\nindependent-particle HOMO-LUMO transitio ns, while for higher Si contents\nstrong mixing of transitions is found. Within T DLDA the first peak is slightly\nhigher in energy than in earlier independent-par ticle calculations. However,\nthe absorption onset and in particular its composit ion dependence is similar\nto independent-particle results. Moreover, classical depolarization effects are\nresponsible for a very strong suppression of the abs orption intensity. We show\nthat they can be taken into account in a simpler way using Maxwell-Garnett\nclassical effective-medium theory. Emission spectra are in vestigated by\ncalculating the absorption of excited nanocrystals at their relaxe d geometry.\nThe structural contribution to the Stokes shift is about 0.5 eV. Th e\ndecomposition of the emission spectra in terms of independent-particle transit\nions is similar to what is found for absorption. For the emission, very weak\ntra nsitions are found in Ge-rich clusters well below the strong absorption\nonset.",
        "positive": "High-Entropy Monoborides: Towards Superhard Materials: Single-phase high-entropy monoborides (HEMBs) of the CrB prototype structure\nhave been synthesized for the first time. Reactive spark plasma sintering of\nball milled mixtures of elemental precursor powders produced bulk\n(V0.2Cr0.2Nb0.2Mo0.2Ta0.2)B, (V0.2Cr0.2Nb0.2Mo0.2W0.2)B, and\n(V0.2Cr0.2Nb0.2Ta0.2W0.2)B HEMB specimens of ~98.3-99.5% relative densities.\nVickers hardness was measured to be ~22-26 GPa at an indentation load of 9.8 N\nand ~32-37 GPa at 0.98 N. In particular, the load-dependent hardness of\n(V0.2Cr0.2Nb0.2Ta0.2W0.2)B is higher than those of ternary (Ta0.5W0.5)B\n(already considered as superhard) and hardest reported high-entropy metal\ndiborides, and on a par with the classical superhard boride WB4."
    },
    {
        "anchor": "On the statistical correlations of random polarization and electric\n  depolarization fields in ferroelectrics: A conceptual problem of the electric-field mediated polarization correlations\nduring a stochastic formation of polarization domain structure in\nferroelectrics is addressed by using an exactly solvable stochastic model of\npolarization development in a uniaxial ferroelectric [Phys. Rev. B 107, 144109\n(2023)]. A full set of time-dependent two-point correlation coefficients\nbetween all random variables is derived analytically, evaluated numerically and\npresented graphically in 3D. They are particularly required for the analysis of\nnonlinear phenomena involving spatial dispersion like optical second harmonic\ngeneration and scattering.",
        "positive": "Epitaxial NaxCoO2 Thin Films via Molecular-Beam Epitaxy and Topotactic\n  Transformation: a Model System for Sodium Intercalation: Renewable energy sources such as solar and wind are critical to combatting\nglobal warming. Nevertheless, their intermittent energy generation requires the\ndevelopment of large-scale grid energy storage, in contrast to the on-demand\ngeneration of coal-based power plants. Sodium-ion batteries offer a promising\npotential technology, yet because sodium ions are larger than lithium ions,\nsodium-ion intercalation results in more drastic structural rearrangements. An\nimproved understanding of structural dynamics and ionic diffusion pathways is\ncrucial to developing more durable sodium-ion batteries. Here we synthesize\nepitaxial NaxCoO2 by using molecular-beam epitaxy and topotactic\ntransformation. In the synthesized epitaxial films, the CoO2 layers are canted\nwith respect to the film surface, allowing electrochemical extraction of sodium\nions, which we confirm via ex-situ x-ray diffraction. We anticipate the\nepitaxial thin films reported here to enable future operando studies of\ninterfaces, subtle lattice distortions, and microstructure during\nelectrochemical cycling."
    },
    {
        "anchor": "Electrochemical solid-state amorphization in the immiscible Cu-Li\n  system: Size matters: As a typical immiscible binary system, copper (Cu) and lithium (Li) show no\nalloying and chemical intermixing under normal circumstances. A notable example\nthat takes advantages of the immiscibility between Cu and Li is the widespread\nutilization of Cu foils as the anodic current collector in Li-ion batteries.\nHere we show that the nanoscale size effect can play a subtle yet critical role\nin mediating the chemical activity of Cu and therefore its miscibility with Li,\nsuch that the electrochemical alloying and solid-state amorphization will occur\nin such an immiscible system when decreasing Cu nanoparticle sizes into\nultrasmall range. This unusual observation was accomplished by performing\nin-situ studies of the electrochemical lithiation processes of individual CuO\nnanowires inside a transmission electron microscopy (TEM). Upon lithiation, CuO\nnanowires are first electrochemically reduced to form discrete ultrasmall Cu\nnanocrystals that, unexpectedly, can in turn undergo further electrochemical\nlithiation to form amorphous CuLix nanoalloys. Real-time dynamic observations\nby in-situ TEM unveil that there is a critical grain size (ca. 6 nm), below\nwhich the crystalline Cu nanoparticles can be continuously lithiated and\namorphized. Electron energy loss spectra indicate that there is a net charge\ntransfer from Li to Cu in the amorphous CuLix nanoalloys. Another intriguing\nfinding is that the amorphous alloying phenomena in Cu-Li system is reversible,\nas manifested by the in-situ observation of electron-beam-induced delithiation\nof the as-formed amorphous CuLix nanoalloys.",
        "positive": "Prediction of the Weyl semimetal in the orthorhombic MoTe2: We investigate the orthorhombic phase (Td) of layered\ntransition-metal-dichalcogenide MoTe$_2$ as a Weyl semimetal candidate, which\nwas discovered to be a superconductor in our recent experiment. MoTe$_2$\nexhibits four pairs of Weyl points lying slightly ($\\sim$ 6 meV) above the\nFermi energy in the bulk band structure. Unlike its cousin WTe$_2$, which was\npredicted to be a type-II Weyl semimetal recently, the spacing between each\npair of Weyl points is found to be as large as 4 percent of the reciprocal\nlattice in MoTe$_2$ (six times larger than that of WTe$_2$). When projected to\nthe surface, Weyl points are connected by Fermi arcs, which can be easily\nverified by ARPES due to the large Weyl point separation. In addition, we show\nthat the correlation effect or strain can drive MoTe$_2$ from the type-II to\ntype-I Weyl semimetal."
    },
    {
        "anchor": "Transition metal impurities in Silicon: Computational search for a\n  semiconductor qubit: Semiconductors offer a promising platform for physical implementation of\nqubits, but their broad adoption is presently hindered by limited scalability\nand/or very low operating temperatures. Learning from the nitrogen-vacancy\ncenters in diamond, our goal is to find equivalent optically active point\ndefect centers in crystalline silicon, which could be advantageous for their\nscalability and integration with classical devices. Transition metal (TM)\nimpurities in silicon are common paramagnetic deep defects, but a comprehensive\ntheoretical study of the whole 3$d$ series that considers generalized Koopmans'\ncondition is missing. We apply the HSE06(+U) method to examine their potential\nas optically active spin qubits and identify seven TM impurities that have\noptically allowed triplet-triplet transitions within the silicon band gap.\nThese results provide the first step toward silicon-based qubits with higher\noperating temperatures for quantum sensing. Additionally, these point defects\ncould lead to spin-photon interfaces in silicon-based qubits and devices for\nmid-infrared free-space communications.",
        "positive": "Physical properties of the thermoelectric cubic lanthanum chalcogenides\n  La3-yX4 (X=S,Se,Te) from first-principles: We report ab-initio calculations of the stability, lattice dynamics,\nelectronic and thermoelectric properties of cubic La3-yX4 (X=S,Se,Te) materials\nin view of analyzing their potential for thermoelectric applications. The\nlanthanum motions are strongly coupled to the tellurium motions in the\ntelluride, whereas the motions of both types of atoms are decoupled in the\nsulfides. Nevertheless, this has no impact on their thermal properties because\nexperimentally all compounds have low thermal conductivity. We believe that\nthis is due to Umklapp scattering of the acoustical modes, notably by the low\nenergy optical modes at about 7-8 meV found in all three chalcogenides, as in\ncage compounds such as skutterudites or clathrates, even though there are no\ncages in the cubic Th3P4 structure. We find that the energy bandgap increases\nfrom the telluride to the sulfide in good agreement with the experiments.\nHowever, due to their similar band structure, we find that all three compounds\nhave almost identical thermoelectric properties. Our results agree\nqualitatively with the experiments, especially in the case of the telluride for\nwhich a great amount of data exists. All our results indicate that the sulfides\nhave strong potential for thermoelectricity and could replace the tellurides if\nthe charge carrier concentration is optimized. Finally, we predict also a\nlarger maximum ZT for the p-type doped materials than for the n-type doped\nones, even though compounds with p-doping have still to be synthesized. Thus\nour results indicate the possibility to make high temperature performing\nthermo-generators based only on La3X4 compounds."
    },
    {
        "anchor": "The effects of Vanadium on the strength of a bcc Fe \u03a33(111)[1-10]\n  grain boundary: The effects of micro-alloying element, vanadium, on a bcc Fe \\Sigma\n3(111)[1-10] symmetric tilt grain boundary strength are studied using density\nfunctional theory calculations. The lowest energy configuration of the grain\nboundary structure are obtained from the first-principles calculations. The\nsubstitutional and interstitial point defect formation energies of vanadium in\nthe grain boundary are compared. The substitutional defect is prefered to\ninterstitial one. The segregation energies of vanadium onto the grain boundary\nand its fractured surfaces are computed. The cohesive energy calculation of the\ngrain boundary with and without vanadium show that vanadium strengthen the bcc\niron \\Sigma 3(111)[1-10] grain boundary.",
        "positive": "A Computational Method for Studying Vibrational Mode Dynamics: The traditional picture of heat transfer in solids by atomic vibrations, also\nknown as phonons, involves phonons scattering with each other like gas\nparticles and is commonly referred to as the phonon gas model (PGM). This\nphysical picture accounts for interactions among propagating (i.e., plane wave\nmodulated) vibrational modes in an ideal crystal, but it becomes problematic\nwhen describing non-propagating modes arising in realistic non-idealized\nsystems. Here, we introduce a more general formalism for studying phonon\ntransport, which involves projection of the interatomic interactions themselves\n(i.e., not just the atom motion), onto the normal modes of the system. This\nshows, for the first time, how energy is exchanged between modes in real-time\nduring molecular dynamics (MD) simulations, as opposed to other MD methods\nwhich use inferences based on correlations, or other time averaged schemes that\ndo not preserve specific features in the real-time dynamics. Applying this\nformalism to the example case of modes interacting in a superlattice, we\nillustrate a new perspective on how phonon transport occurs, whereby individual\nnormal modes share energy through specific channels of interaction with other\nmodes. We also highlight that while a myriad of interaction pathways exist,\nonly a tiny fraction of these pathways actually transfer significant amounts of\nenergy, which is surprising. The approach allows for the prediction and\nsimulation of these mode/phonon interactions, thus unveiling the real-time\ndynamics of phonon behavior and advancing our ability to understanding and\nengineer phonon transport."
    },
    {
        "anchor": "A Minimalist Model of Characteristic Earthquakes: In a spirit akin to the sandpile model of self-organized criticality, we\npresent a simple statistical model of the cellular-automaton type which\nproduces an avalanche spectrum similar to the characteristic-earthquake\nbehavior of some seismic faults. This model, that has no parameter, is amenable\nto an algebraic description as a Markov Chain. This possibility illuminates\nsome important results, obtained by Monte Carlo simulations, such as the\nearthquake size-frequency relation and the recurrence time of the\ncharacteristic earthquake.",
        "positive": "Defects drive the tribocharging strength of PTFE: If polytetrafluoroethylene (PTFE), commonly known as Teflon, is put into\ncontact and rubbed against another material, almost surely it will be more\neffective than its counterpart in collecting negative charges. This simple,\nbasic property is captured by the so called triboelectric series, where PTFE\nranks extremely high, and that qualitatively orders materials in terms of their\nability to electrostatically charge upon contact and rubbing. However, while\nclassifying materials, the series does not provide an explanation of their\ntriboelectric strength, besides a loose correlation with the workfunction.\nIndeed, despite being an extremely familiar process, known from centuries,\ntribocharging is still elusive and not fully understood. In this work we employ\ndensity functional theory to look for the origin of PTFE tribocharging\nstrength. We study how charge transfers when pristine or defective PTFE is put\nin contact with different clean and oxidised metals. Our results show the\nimportant role played by defects in enhancing charge transfer. Interestingly\nand unexpectedly our results show that negatively charged chains are more\nstable than neutral ones, if slightly bent. Indeed deformations can be easily\npromoted in polymers as PTFE, especially in tribological contacts. These\nresults suggest that, in designing materials in view of their triboelectric\nproperties, the characteristics of their defects could be a performance\ndetermining factor."
    },
    {
        "anchor": "Massive damage generation accompanying pyramidal slip in hexagonal-close\n  packed magnesium: an origin for its high hardening and brittleness: Mg represents a group of technically important hexagonal-close packed (hcp)\nmetals whose mechanical behaviors are very different from body-centered cubic\n(bcc) and face-centered cubic (fcc) metals and the underlying mechanisms remain\npoorly-understood. It has been long known that Mg has high hardening and low\nductility, and this was conventionally attributed to the scarce of active\npyramidal slip. Recently immobilization of pyramidal dislocations was proposed\nto be the origins. Here we present a different scenario that has hitherto never\nbeen reported for Mg: mobile screw pyramidal dislocations double cross-slip and\ncontinue to double cross-slip as they glide, generating abundant vacancy\nclusters on the slipped planes. These vacancy clusters hinder subsequent\ndislocation motion and thus directly result in hardening; their accumulation as\nplastic deformation proceeds eventually causes premature fracture, i.e.\nbrittleness. The massive damage accompanying pyramidal slip discovered here\nprovides a different explanation for the long known hardening and brittleness\nof Mg, and suggests that sufficient amount of pyramidal dislocations could\nstill be insufficient to effectively accommodate plasticity. Stabilizing\npyramidal dislocation motion to avoid cross-slip and subsequent damage\ngeneration is also essential for property-improvement. The instability of\npyramidal slip, manifested as continuous cross-slip here (could be different\nelsewhere), originates from its huge Burgers vector and could be a common\nfeature of its kind. The detailed cross-slip mechanism also provides insights\ninto the poorly known instabilities and complicated behavior of dislocations in\na broader range of crystals with low symmetry and/or large Burgers vectors,\nincluding other hcp metals and ceramics.",
        "positive": "Generation and transport of photoexcited electrons in single-crystal\n  diamond: We report time-dependent photocurrent and transport measurements of\nsub-bandgap photoexcited carriers in nitrogen-rich (type Ib), single-crystal\ndiamond. Transient carrier dynamics are characteristic of trapping conduction\nwith long charge storage lifetimes of ~3 hours. By measuring the photoexcited\nHall effect we confirm that the charge carriers are electrons and by varying\nthe excitation energy we observe a strong turn-on in the photoconduction at\n~1.9 eV. These findings shed new light on sub-bandgap states in nitrogen doped\nsingle-crystal diamond."
    },
    {
        "anchor": "High-pressure characterization of multifunctional CrVO4: The structural stability and physical properties of CrVO4 under compression\nwere studied by X-ray diffraction, Raman spectroscopy, optical absorption,\nresistivity measurements, and ab initio calculations up to 10 GPa.\nHigh-pressure X-ray diffraction and Raman measurements show that CrVO4\nundergoes a phase transition from the ambient pressure orthorhombic CrVO4-type\nstructure (Cmcm space group, phase III) to the high-pressure monoclinic CrVO4-V\nphase, which is isomorphic to the wolframite structure. Such a phase transition\n(CrVO4-type - wolframite), driven by pressure, also was previously observed in\nindium vanadate. The crystal structure of both phases and the pressure\ndependence in unit-cell parameters, Raman-active modes, resistivity, and\nelectronic band gap, is reported. Vanadium atoms are sixth-fold coordinated in\nthe wolframite phase, which is related to the collapse in the volume at the\nphase transition. Besides, we also observed drastic changes in the phonon\nspectrum, a drop of the band-gap, and a sharp decrease of resistivity. All the\nobserved phenomena are explained with the help of first-principles\ncalculations.",
        "positive": "High rate nanofluidic energy absorption in porous zeolitic frameworks: Optimal mechanical impact absorbers are reusable and exhibit high specific\nenergy absorption. The forced intrusion of liquid water in hydrophobic\nnanoporous materials, such as zeolitic imidazolate frameworks (ZIFs), presents\nan attractive pathway to engineer such systems. However, to harness their full\npotential, it is crucial to understand the underlying water intrusion and\nex-trusion mechanisms under realistic, high-rate deformation conditions.\nHerein, we report a critical increase of the energy absorption capacity of\nconfined water-ZIF systems at elevated strain rates. Starting from ZIF-8 as\nproof-of-concept, we demonstrate that this attractive rate depend-ence is\ngenerally applicable to cage-type ZIFs but disappears for channel-containing\nzeolites. Molecular simulations reveal that this phenomenon originates from the\nintrinsic nanosecond timescale needed for critical-sized water clusters to\nnucleate inside the nanocages, expediting water transport through the\nframework. Harnessing this fundamental understanding, design rules are\nformulated to construct effective, tailorable, and reusable impact energy\nabsorbers for challenging new applications."
    },
    {
        "anchor": "Correlation between Thermal Properties, Electrical Conductivity and\n  Crystal Structure in the BaCe0.80Y0.20O2.9 Proton Conductor: In this paper we report an extensive neutron diffraction investigation at\nhigh temperature on the BaCe0.80Y0.20O2.9 proton conducting material. Our\nresults precisely define the structural evolution of the compound as a function\nof temperature which is from a monoclinic (room temperature) to a cubic (800C)\nstructure. Neutron data have been correlated to calorimetric measurements (TGA\nand DSC) and conductivity properties of the material.",
        "positive": "Study of 57Fe Mossbauer effect in RFe2Zn20 ( R = Lu, Yb, Gd): We report measurements of 57Fe Mossbauer spectra for RFe2Zn20 ( R = Lu, Yb,\nGd) from ~ 4.5 K to room temperature. The obtained isomer shift values are very\nsimilar for all three compounds, their temperature dependence was analyzed\nwithin the Debye model and resulted in an estimate of the Debye temperatures of\n450-500 K. The values of quadrupole splitting at room temperature change with\nthe cubic lattice constant a in a linear fashion. For GdFe2Zn20, ferromagnetic\norder is seen as an appearance of a sextet in the spectra. The 57Fe site\nhyperfine field for T = 0 was evaluated to be ~ 2.4 T."
    },
    {
        "anchor": "Validation of secondary fluorescence excitation in quantitative X-ray\n  fluorescence analysis of thin alloy films: X-ray fluorescence (XRF) analysis is a widely applied technique for the\nquantitative analysis of thin films up to the $\\mu$m scale because of its\nnon-destructive nature and because it is easily automated. When low\nuncertainties of the analytical results in the few percent range are required,\nthe non-linear secondary fluorescence effect in multi-elemental samples may\ncomplicate an otherwise straightforward quantification, since it can easily\nexceed a relative contribution of 20%. The conventional solution, to rely on\ngood performing reference samples, is hindered by their low availability,\nespecially for thin film applications. To address this challenge, we\ndemonstrate a flexible production method of multilayered, alloyed thin films\nwith significant secondary fluorescence contributions. We use reference-free\nXRF analysis to validate the reliability of the physical model for secondary\nfluorescence, which includes a thorough uncertainty estimation. The\ninvestigated specimens are being qualified as calibration samples for XRF or\nother quantitative analyses.",
        "positive": "An infrared probe of the insulator-to-metal transition in GaMnAs and\n  GaBeAs: We report infrared studies of the insulator-to-metal transition (IMT) in GaAs\ndoped with either magnetic (Mn) or non-magnetic acceptors (Be). We observe a\nresonance with a natural assignment to impurity states in the insulating regime\nof Ga$_{1-x}$Mn$_x$As, which persists across the IMT to the highest doping\n(16%). Beyond the IMT boundary, behavior combining insulating and metallic\ntrends also persists to the highest Mn doping. Be doped samples however,\ndisplay conventional metallicity just above the critical IMT concentration,\nwith features indicative of transport within the host valence band."
    },
    {
        "anchor": "Direct TEM observation and quantification of the Gibbs-Thomson effect in\n  a nickel superalloy: Gibbs-Thompson effect is the general term referring to the influence of\ninterfaces on the course of phase transformations such as precipitation or\nsolidification. Whilst attention is most often focused on the Gibbs-Thomson\neffect on nucleation, growth and coarsening, the present study considers the\nreverse process of precipitate dissolution in a nickel-base superalloy during\nin situ TEM observation. The presence of several distinct populations of\ngamma-prime precipitates (primary, secondary, tertiary and grain boundary)\nallows the differences due to particle size to be quantified and interpreted.\nImportant implications arise for the selection of heat treatment schedules for\nnickel-base superalloys and other alloy systems.",
        "positive": "First-Principles Study of Electron Linewidths in Graphene: We present first-principles calculations of the linewidths of low-energy\nquasiparticles in n-doped graphene arising from both the electron-electron and\nthe electron-phonon interactions. The contribution to the electron linewidth\narising from the electron-electron interactions vary significantly with\nwavevector at fixed energy; in contrast, the electron-phonon contribution is\nvirtually wavevector-independent. These two contributions are comparable in\nmagnitude at a binding energy of ~0.2 eV, corresponding to the optical phonon\nenergy. The calculated linewidths, with both electron-electron and\nelectron-phonon interactions included, explain to a large extent the linewidths\nseen in recent photoemission experiments."
    },
    {
        "anchor": "First principle calculations with SIC correction of Fe-doped CuO\n  compound: In this work the electronic properties of Fe doped CuO thin films are studied\nby using a standard density functional theory. This approach is based on the\nabinitio calculations under the Korringa Kohn Rostoker coherent potential\napproximation. We carried out our investigations in the framework of the\ngeneral gradient approximation and self interaction corrected. The density of\nstates in the energy diagrams are presented and discussed. The computed\nelectronic properties of the studied compound confirm the half metalicity\nnature of this material. In addition, the absorption spectra of the studied\ncompound within the Generalized Gradient Approximation, as proposed by Perdew\nBurke Ernzerhof approximations are examined. When compared with the pure CuO,\nthe Fermi levels of doped structures are found to move to the higher energy\ndirections. To complete this study, the effect of Fe doping method in CuO has\ntransformed the material to half metallic one. We found a high wide impurity\nband in two cases of approximations methods.",
        "positive": "Photoconversion in the HIT solar cells: Theory vs experiment: We obtain theoretical expressions for the photocurrent in the Heterojunction\nsolar cells with Intrinsic Thin layer (HIT cells). Our calculations take into\naccount tunneling of electrons and holes through wide-bandgap layers of\n$\\alpha$-Si:H or $\\alpha$-SiC:H. We introduce the criteria, under which\ntunneling does not lead to the deterioration of solar cell characteristics, in\nparticular, to the reduction of the short-circuit current and open-circuit\nvoltage. We propose an algorithm to compute the photoconversion efficiency of\nHIT elements, taking into account the peculiarities of the open-circuit voltage\ngeneration, in particular, its rather high values. We test our theoretical\npredictions against the experimental results. For this, we fabricate HIT\nelements with the efficiency of about $20\\,\\%$. We measured the temperature\ndependence of the short-circuit current, open-circuit voltage, photoconversion\npower, and fill factor of the current-voltage curve of these elements in a wide\ntemperature range from 80 to 420\\,K. In the low-temperature range, the\nopen-circuit voltage and the photoconversion power decrease on cooling. At $T\n\\ge 200$\\,K, the theoretical expressions and the experimental curves agree\nrather well. The behavior of the fill factor and output power at low\ntemperatures is explained by the increase of the series resistance on cooling.\nWe discuss the reasons behind the reduction of the power temperature\ncoefficient in HIT elements. We show that they are related to the low value of\nthe combined surface and volume recombination rate. Finally, we derive a\ntheoretical expression for the HIT element's operation temperature under\nnatural working conditions."
    },
    {
        "anchor": "Continuum Model and Numerical Method for Dislocation Structure and\n  Energy of Grain Boundaries: We present a continuum model to determine the dislocation structure and\nenergy of low angle grain boundaries in three dimensions. The equilibrium\ndislocation structure is obtained by minimizing the grain boundary energy that\nis associated with the constituent dislocations subject to the constraint of\nFrank's formula. The orientation-dependent continuous distributions of\ndislocation lines on grain boundaries are described conveniently using the\ndislocation density potential functions, whose contour lines on the grain\nboundaries represent the dislocations. The energy of a grain boundary is the\ntotal energy of the constituent dislocations derived from discrete dislocation\ndynamics model, incorporating both the dislocation line energy and reactions of\ndislocations. The constrained energy minimization problem is solved by the\naugmented Lagrangian method and projection method. Comparisons with atomistic\nsimulation results show that our continuum model is able to give excellent\npredictions of the energy and dislocation densities of both planar and curved\nlow angle grain boundaries.",
        "positive": "Thermodynamics of carrier-mediated magnetism in semiconductors: We propose a model of carrier-mediated ferromagnetism in semiconductors that\naccounts for the temperature dependence of the carriers. The model permits\nanalysis of the thermodynamic stability of competing magnetic states, opening\nthe door to the construction of magnetic phase diagrams. As an example we\nanalyze the stability of a possible reentrant ferromagnetic semiconductor, in\nwhich increasing temperature leads to an increased carrier density, such that\nthe enhanced exchange coupling between magnetic impurities results in the onset\nof ferromagnetism as temperature is raised."
    },
    {
        "anchor": "Long-range quadrupole electron-phonon interaction from first principles: Lattice vibrations in materials induce perturbations on the electron dynamics\nin the form of long-range (dipole and quadrupole) and short-range (octopole and\nhigher) potentials. The dipole Fr\\\"ohlich term can be included in current\nfirst-principles electron-phonon ($e$-ph) calculations and is present only in\npolar materials. The quadrupole $e$-ph interaction is present in both polar and\nnonpolar materials, but currently it cannot be computed from first principles.\nHere we show an approach to compute the quadrupole $e$-ph interaction and\ninclude it in ab initio calculations of $e$-ph matrix elements. The accuracy of\nthe approach is demonstrated by comparing with direct density functional\nperturbation theory calculations. We apply our method to silicon as a case of a\nnonpolar semiconductor and tetragonal PbTiO$_3$ as a case of a polar\npiezoelectric material. In both materials we find that the quadrupole term\nstrongly impacts the $e$-ph matrix elements. Analysis of $e$-ph interactions\nfor different phonon modes reveals that the quadrupole term mainly affects\noptical modes in silicon and acoustic modes in PbTiO$_3$, although the\nquadrupole term is needed for all modes to achieve quantitative accuracy. The\neffect of the quadrupole $e$-ph interaction on electron scattering processes\nand transport is shown to be important. Our approach enables accurate studies\nof $e$-ph interactions in broad classes of nonpolar, polar and piezoelectric\nmaterials.",
        "positive": "Competition of disorder and electron-phonon coupling in\n  2H-TaSe$_{2-x}$S$_x$ ($0\\le x\\le 2$) as evidenced by Raman spectroscopy: The vibrational properties of 2H-TaSe$_{2-x}$S$_x$ ($0 \\le x \\le 2$) single\ncrystals were probed using Raman spectroscopy and density functional theory\ncalculations. The end members revealed two out of four symmetry-predicted Raman\nactive modes, together with the pronounced two-phonon structure, attributable\nto the enhanced electron-phonon coupling. Additional peaks become observable\ndue to crystallographic disorder for the doped samples. The evolution of the\nE$_{2g}^2$ mode Fano parameter reveals that the disorder has weak impact on\nelectron-phonon coupling, which is also supported by the persistence of\ntwo-phonon structure in doped samples. As such, this research provides thorough\ninsights into the lattice properties, the effects of crystallographic disorder\non Raman spectra, and the interplay of this disorder with the electron-phonon\ncoupling in 2H-TaSe$_{2-x}$S$_x$ compounds."
    },
    {
        "anchor": "Structure and morphology evolution of concave-shaped SiC {0001} surfaces\n  in liquid silicon: Concave-shaped 4H-SiC {0001} surfaces have been prepared and reconstructed in\npure liquid silicon for investigating the structure and morphology evolution of\nthe SiC surface as a function of both azimuthal and off-axis angles. Different\nsurface characteristics are revealed on two polar surfaces where only the Si\nface reflects the six-fold symmetry of 4H-SiC crystal. On the Si face, the step\nbunching along the <1100> direction is stronger than the <1120> direction,\nwhich is related to the bonding state at the step edge. More significant step\nbunching is observed on the C face whereas it is not sensitive to azimuthal\norientation. The extent of step faceting is stronger on the Si face. The step\nfaceting is independent of the off angle on both polarities of SiC {0001}\nsurfaces.",
        "positive": "Spin transport properties in a naphthyl diamine derivative film\n  investigated by the spin pumping: We report the spin transport properties in a thin film of a naphthyl diamine\nderivative: N,N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)-2,2'-dimethylbenzidine\n(alpha-NPD). In a palladium(Pd)/alpha-NPD/Ni80Fe20 tri-layer structure sample,\na pure spin current is generated in the alpha-NPD layer with the spin pumping\ndriven by ferromagnetic resonance (FMR). The generated spin current is absorbed\ninto the Pd layer, and converted into a charge current with the inverse\nspin-Hall effect (ISHE) in Pd. An electromotive force due to the ISHE in the Pd\nlayer is observed under the FMR of the Ni80Fe20 layer, which is clear evidence\nfor the spin transport in an alpha-NPD film. The spin diffusion length in an\nalpha-NPD film is estimated to be about 62 nm at room temperature, which is\nlong enough as a spin transport material for spintronic devices."
    },
    {
        "anchor": "An Improved Real--Space Genetic Algorithm for Crystal Structure and\n  Polymorph Prediction: Existing Genetic Algorithms for crystal structure and polymorph prediction\ncan suffer from stagnation during evolution, with a consequent loss of\nefficiency and accuracy. An improved Genetic Algorithm (GA) is introduced\nherein which penalizes similar structures and so enhances structural diversity\nin the population at each generation. This is shown to improve the quality of\nresults found for the theoretical prediction of simple model crystal\nstructures. In particular, this method is demonstrated to find three new\nzero--temperature phases of the Dzugutov potential that have not been\npreviously reported.",
        "positive": "Full ab initio band structure analysis of interband and intraband\n  contributions for third harmonic generation coefficient of bulk silicon:\n  implementation and application of the sum-over-states: We fully implement the Aversa and Sipe sum-over-states formulism and make a\nfull ab initio band structure analysis of interband and intraband contributions\nfor the third-order nonlinear optical susceptibilities of bulk silicon. The\nband structure and momentum matrix elements were calculated by using the highly\naccurate all-electron full potential linearized augmented plane wave method\nwithin the local density approximation. The convergence tests including the\nscissor correction with different k-points meshes and empty states were\nperformed. Both real and imaginary parts of susceptibility were directly\ncalculated and checked by the Kramers-Kronig relation. The converged results\nare compared with other theoretical and experimental ones and in agreement with\nthe recent ab initio real-time-based calculation. The nonlinear optical\ncoefficient comes from three parts: the pure interband contribution (Pinter),\nthe modulation of interband terms by intraband terms (Pmod), and the intraband\ncontribution (Jintra). For each part, the origin of enhanced peaks is explored\nby tracing the sum-over-states process. The interband contribution is found to\nbe dramatically modulated by the intraband contribution."
    },
    {
        "anchor": "Hot electron cooling in three-dimensional Dirac fermion systems at low\n  temperature: effect of screening: Hot electron cooling rate P, due to acoustic phonons, is investigated in\nthree-dimensional Dirac fermion systems at low temperature taking account of\nscreening of electron-acoustic phonon interaction. P is studied as a function\nof electron temperature T_e and electron concentration n_e. Screening is found\nto suppress P very significantly for about T_e < 0.5 K and its effect reduces\nconsiderably for about T_e > 1K in Cd_3As_2 . In Bloch-Gruniesen (BG) regime,\nfor screened (unscreened) case T_e dependence is P ~ T_e^ 9 (T_e^ 5) and ne\ndependence gives P ~ n_e ^-5/3(n_e^-1/3). The T_e dependence is characteristics\nof 3D phonons and n_e dependence is characteristics of 3D Dirac fermions. In BG\nregime, screening effect is found to enhance for larger n_e. Screening is found\nto reduce the range of validity of BG regime temperature. Plot of P / T_e^ 4 vs\nT_e shows a maximum at temperature T_e m which shifts to higher values for\nlarger n_e. Interesting observation is that maximum of P / T_e^4 is nearly same\nfor different n_e and T_em / n_e^ 1/3 appears to be nearly constant. More\nimportantly, we propose, the n_e dependent measurements of P would provide a\nclearer signature to identify 3D Dirac semimetal phase.",
        "positive": "Quantum Transport and Band Structure Evolution under High Magnetic Field\n  in Few-Layer Tellurene: Quantum Hall effect (QHE) is a macroscopic manifestation of quantized states\nwhich only occurs in confined two-dimensional electron gas (2DEG) systems.\nExperimentally, QHE is hosted in high mobility 2DEG with large external\nmagnetic field at low temperature. Two-dimensional van der Waals materials,\nsuch as graphene and black phosphorus, are considered interesting material\nsystems to study quantum transport, because it could unveil unique host\nmaterial properties due to its easy accessibility of monolayer or few-layer\nthin films at 2D quantum limit. Here for the first time, we report direct\nobservation of QHE in a novel low-dimensional material system:\ntellurene.High-quality 2D tellurene thin films were acquired from recently\nreported hydrothermal method with high hole mobility of nearly 3,000 cm2/Vs at\nlow temperatures, which allows the observation of well-developed\nShubnikov-de-Haas (SdH) oscillations and QHE. A four-fold degeneracy of Landau\nlevels in SdH oscillations and QHE was revealed. Quantum oscillations were\ninvestigated under different gate biases, tilted magnetic fields and various\ntemperatures, and the results manifest the inherent information of the\nelectronic structure of Te. Anomalies in both temperature-dependent oscillation\namplitudes and transport characteristics were observed which are ascribed to\nthe interplay between Zeeman effect and spin-orbit coupling as depicted by the\ndensity functional theory (DFT) calculations."
    },
    {
        "anchor": "Accurate, uncertainty-aware classification of molecular chemical motifs\n  from multi-modal X-ray absorption spectroscopy: Accurate classification of molecular chemical motifs from experimental\nmeasurement is an important problem in molecular physics, chemistry and\nbiology. In this work, we present neural network ensemble classifiers for\npredicting the presence (or lack thereof) of 41 different chemical motifs on\nsmall molecules from simulated C, N and O K-edge X-ray absorption near-edge\nstructure (XANES) spectra. Our classifiers not only reach a maximum average\nclass-balanced accuracy of 0.99 but also accurately quantify uncertainty. We\nalso show that including multiple XANES modalities improves predictions notably\non average, demonstrating a \"multi-modal advantage\" over any single modality.\nIn addition to structure refinement, our approach can be generalized for broad\napplications with molecular design pipelines.",
        "positive": "Quasiparticle Electronic Structure of Two-Dimensional\n  Heterotriangulene-Based Covalent Organic Frameworks Adsorbed on Au(111): The modular nature and unique electronic properties of two-dimensional (2D)\ncovalent organic frameworks (COFs) make them an attractive option for\napplications in catalysis, optoelectronics, and spintronics. The fabrications\nof such devices often involve interfaces formed between COFs and substrates. In\nthis work, we employ the first-principles GW approach to accurately determine\nthe quasiparticle electronic structure of three 2D carbonyl bridged\nheterotriangulene-based COFs featuring kagome lattice, with their properties\nranging from a semi-metal to a wide-gap semiconductor. Moreover, we study the\nadsorption of these COFs on Au(111) surface and characterize the quasiparticle\nelectronic structure at the heterogeneous COF/Au(111) interfaces. To reduce the\ncomputational cost, we apply the recently developed dielectric embedding GW\napproach and show that our results agree with existing experimental measurement\non the interfacial energy level alignment. Our calculations illustrate how the\nmany-body dielectric screening at the interface modulates the energies and\nshapes of the kagome bands, the effective masses of semiconducting COFs, as\nwell as the Fermi velocity of the semi-metallic COF."
    },
    {
        "anchor": "Dirac node engineering and flat bands in doped Dirac materials: We suggest the tried approach of impurity band engineering to produce flat\nbands and additional nodes in Dirac materials. We show that surface impurities\ngive rise to nearly flat impurity bands close to the Dirac point. The\nhybridization of the Dirac nodal state induces the splitting of the surface\nDirac nodes and the appearance of new nodes at high-symmetry points of the\nBrillouin zone. The results are robust and not model dependent: the\ntight-binding calculations are supported by a low-energy effective model of a\ntopological insulator surface state hybridized with an impurity band. Finally,\nwe address the effects of electron-electron interactions between localized\nelectrons on the impurity site. We confirm that the correlation effects, while\nproducing band hybridization and Kondo effect, keep the hybridized band flat.\nOur findings open up prospects for impurity band engineering of nodal\nstructures and flat-band correlated phases in doped Dirac materials.",
        "positive": "Pressure dependent physical properties of a potential high-TC\n  superconductor ScYH6: insights from first-principles study: We have investigated the structural, elastic, electronic, thermophysical,\nsuperconducting, and optical properties of ScYH6 under uniform hydrostatic\npressures up to 25 GPa, using the density functional theory (DFT) formalism.\nMost of results reported here are novel. The compound ScYH6 has been found to\nbe elastically and thermodynamically stable within the pressure range\nconsidered. The compound is brittle; the brittleness decreases with increasing\npressure. The elastic anisotropy is low and the machinability index is moderate\nwhich increases gradually with rising pressure. The compound is a hard\nmaterial. The electronic band structure shows weakly metallic character with\nlow density of states at the Fermi level. The Debye temperature of the compound\nis high and increases with increasing pressure. The Gr\\\"uneisen parameter of\nScYH6 is low and the phonon thermal conductivity is high at room temperature.\nThe compound is a very efficient reflector of infrared radiation. The compound\nis also an efficient absorber of visible and ultraviolet light. The overall\neffect of pressure on optical parameters is small. We have also investigated\nthe pressure induced changes in the predicted superconducting state properties\nby considering the changes in the electronic density of states at the Fermi\nlevel, Debye temperature, and the repulsive Coulomb pseudopotential. The\nsuperconducting transition temperature is found to increase gradually with\nincreasing pressure."
    },
    {
        "anchor": "Tunable Indirect-Direct Transition of Few-Layer SnSe via Interface\n  Engineering: Tin Selenide (SnSe) is one of the best thermoelectric materials reported to\ndate. The possibility of growing few-layer SnSe helped boost the interest in\nthis long-known, earth abundant material. Pristine SnSe in bulk, mono- and\nfew-layer forms are reported to have indirect electronic bandgaps. Possible\nindirect-direct transition in SnSe is attractive for its optoelectronic-related\napplications. Based on the results from first principles Density Functional\nTheory (DFT) calculations, we carefully analyzed electronic band structures of\nbulk, and bilayer SnSe with various interlayer stackings. We report the\npossible stacking-dependent indirect-direct transition of bilayer SnSe. By\nfurther analysis, our results reveal that it is the directionality of\ninterlayer interactions that determine the critical features of their\nelectronic band structures. In fact, by engineering the interface stacking\nbetween layers, it is possible to achieve few-layer SnSe with direct electronic\nband gap. This study provides fundamental insights to design few-layer SnSe and\nSnSe heterostructures for electronic/optoelectronic applications, where the\ninterface geometry plays a fundamental role in device performance.",
        "positive": "Superspin Glass Mediated Giant Spontaneous Exchange Bias in a\n  Nanocomposite of BiFeO$_3$-Bi$_2$Fe$_4$O$_9$: We observe an enormous $\\textit{spontaneous}$ exchange bias ($\\sim$300-600\nOe) - measured in an unmagnetized state following zero-field cooling - in a\nnanocomposite of BiFeO$_3$ ($\\sim$94%)-Bi$_2$Fe$_4$O$_9$ ($\\sim$6%) over a\ntemperature range 5-300 K. Depending on the path followed in tracing the\nhysteresis loop - positive (p) or negative (n) - as well as the maximum field\napplied, the exchange bias ($H_E$) varies significantly with $\\mid-H_{Ep}\\mid$\n$>$ $\\mid H_{En}\\mid$. The temperature dependence of $H_E$ is nonmonotonic. It\nincreases, initially, till $\\sim$150 K and then decreases as the blocking\ntemperature $T_B$ is approched. All these rich features appear to be\noriginating from the spontaneous symmetry breaking and consequent onset of\nunidirectional anisotropy driven by \"superinteraction bias coupling\" between\nferromagnetic core of Bi$_2$Fe$_4$O$_9$ (of average size $\\sim$19 nm) and\ncanted antiferromagnetic structure of BiFeO$_3$ (of average size $\\sim$112 nm)\nvia superspin glass moments at the shell."
    },
    {
        "anchor": "Excitation of normal modes of a thin elastic plate by moving\n  dislocations: We study the excitation of harmonic waves in thin elastic samples by a single\ndislocation in arbitrary motion. We consider both screw and edge dislocations\nthat move perpendicularly to the surfaces of the layer. In Fourier space the\ndisplacement velocity and dynamic stress fields generated by the motion of the\ndislocations are factored as the product of two terms: one depends on the\nmotion of the dislocation only, while the other is independent of it, and\nrepresents the medium's response. The latter term exhibits poles at frequencies\nthat satisfy the dispersion relation of the harmonic modes of the plate. In the\ncase of a screw dislocation the modes that are excited are a subfamily of the\nantisymmetric Rayleigh-Lamb modes. For an edge dislocation a subfamily of the\nsymmetric Rayleigh-Lamb modes is excited, as well as the lowest lying shear\nmode. The expression corresponding to a uniformly moving screw is worked out in\ndetail; it has singular behavior at velocities coincident with the phase\nvelocities of the allowed modes.",
        "positive": "Flexocoupling impact on the generalized susceptibility and soft phonon\n  modes in the ordered phase of ferroics: Flexoelectric effect impact on the generalized susceptibility and soft\nphonons dispersion was not studied in the long-range ordered phases of\nferroics. The gap in the knowledge motivated us to establish the impact of the\nflexocoupling on the correlation function of the long-range order parameter\nfluctuations in ferroelectric phase of ferroics with local disordering sources.\nWithin Landau-Ginzburg-Devonshire approach we obtained analytical expressions\nfor the generalized susceptibility and phonon dispersion relations in the\nferroelectric phase. Unexpectedly, the joint action of static and dynamic\nflexoelectric effect induces non-diagonal components of generalized\nsusceptibility, which amplitude is proportional to the convolution of the\nspontaneous polarization with flexocoupling constants. The flexocoupling\nessentially broaden the k-spectrum of generalized susceptibility and so\ndecreases the correlation radii, as well as leads to the additional \"pushing\naway\" of the optical and acoustic soft mode phonon branches. The contribution\nof spontaneous polarization via ferroelectric nonlinearity and electrostriction\nmechanisms can lead to both broadening and narrowing on the susceptibility\nk-spectrum. Due to the joint action of flexoelectric coupling and spontaneous\npolarization the degeneration of the transverse optic and acoustic modes\ndisappears in the soft phonon spectrum in a ferroelectric phase in comparison\nwith the spectra in a paraelectric phase. These effects have been studied\nquantitatively for ferroelectric lead zirconate titanate using realistic values\nof static and dynamic flexocouplings and cubic symmetry approximation for the\nelastic properties. Also we derived general expressions for correlation\nfunction for arbitrary symmetry, elastic and electrostrictive anisotropy."
    },
    {
        "anchor": "Lead-free, luminescent perovskite nanocrystals obtained through ambient\n  condition synthesis: Heterovalent substitution of toxic lead is an increasingly popular design\nstrategy to obtain environmentally sustainable variants of the exciting\nmaterial class of halide perovskites. Perovskite nanocrystals (NCs) obtained\nthrough solution-based methods exhibit exceedingly high optical quality.\nUnfortunately, most of these synthesis routes still require reaction under\ninert gas and at very high temperatures. Herein we present a novel synthesis\nroutine for lead-free double perovskite NCs. We combine hot injection and\nligand-assisted reprecipitation (LARP) methods to achieve a low-temperature and\nambient atmosphere-based synthesis for manganese-doped Cs_{2}NaBiCl_{6} NCs. Mn\nincorporation is critical for the otherwise non-emissive material, with a 9:1\nBi:Mn precursor ratio maximizing the bright orange photoluminescence (PL) and\nquantum yield (QY). Higher temperatures slightly increased the material's\nperformance, yet NCs synthesized at room temperature were still emissive,\nhighlighting the versatility of the synthetic approach. Furthermore, the NCs\nshow excellent long-term stability in ambient conditions, facilitating\nadditional investigations and energy-related applications.",
        "positive": "2D ice from first principles: structures and phase transitions: Despite relevance to disparate areas such as cloud microphysics and\ntribology, major gaps in the understanding of the structures and phase\ntransitions of low-dimensional water ice remain. Here we report a first\nprinciples study of confined 2D ice as a function of pressure. We find that at\nambient pressure hexagonal and pentagonal monolayer structures are the two\nlowest enthalpy phases identified. Upon mild compression the pentagonal\nstructure becomes the most stable and persists up to \\textit{ca.} 2 GPa at\nwhich point square and rhombic phases are stable. The square phase agrees with\nrecent experimental observations of square ice confined within graphene sheets.\nWe also find a double layer AA stacked square ice phase, which clarifies the\ndifference between experimental observations and earlier force field\nsimulations. This work provides a fresh perspective on 2D confined ice,\nhighlighting the sensitivity of the structures observed to both the confining\npressure and width."
    },
    {
        "anchor": "Hybrid Improper Ferroelectricity: A Mechanism for Controllable\n  Magnetization-Polarization Coupling: First-principles calculations are presented for the layered perovskite\nCa$_3$Mn$_2$O$_7$. The results reveal a rich set of coupled structural,\nmagnetic and polar domains in which oxygen octahedron rotations induce\nferroelectricity, magnetoelectricity and weak-ferromagnetism. The key point is\nthat the rotation distortion is a combination of two non-polar modes with\ndifferent symmetries. We use the term \"hybrid\" improper ferroelectricity to\ndescribe this phenomenon and discuss how control over magnetism is achieved\nthrough these functional antiferrodistortive octahedron rotations.",
        "positive": "Investigations on the energy balance in TDCB tests: The TDCB test is an established method to determine the critical strain\nenergy release rate of adhesives in mode I. Provided that the adherends stay\nelastic, that the adhesive layer is not too flexible and that inertia effects\ncan be neglected, the experiment allows to identify the work required by the\nadhesive layer per area of crack growth. The evaluation according to the\nstandard does not permit to distinguish between different sources of\ndissipation in the adhesive layer or at the adhesive-adherend interfaces,\nthough. This paper proposes two approaches to gain a more detailed\nunderstanding of the dissipation in mode I crack growth of adhesive layers.\n  The first investigation method uses detailed finite element simulations of\nthe TDCB test based on an elastic-plastic adhesive material model derived from\ntests on bulk specimens. The simulation is used to distinct between the work\nrequired for the plastic deformation of the entire adhesive layer and the work\nconsumed by the crack and the adhesive in its vicinity. The dependence of this\ndistribution of work on the adhesive layer thickness is studied. The second\napproach adds a temperature measurement by an infrared camera to the TDCB test.\nThis measurement allows observation of the thermo-elastic effect in the\nadhesive layer and of the heat generation at the crack. Finally, the results of\nthe two approaches are employed to estimate the energy balance in the TDCB\ntest."
    },
    {
        "anchor": "Re-examining the electronic structure of germanium: A first-principle\n  study: We report results from an efficient, robust, ab-initio method for\nself-consistent calculations of electronic and structural properties of Ge. Our\nnon-relativistic calculations employed a generalized gradient approximation\n(GGA) potential and the linear combination of atomic orbitals (LCAO) formalism.\nThe distinctive feature of our computations stem from the use of\nBagayoko-Zhao-Williams-Ekuma-Franklin (BZW-EF) method. Our results are in\nagreement with experimental ones where the latter are available. In particular,\nour theoretical, indirect band gap of 0.65 eV, at the experimental lattice\nconstant of 5.66 \\AA{}, is in excellent agreement with experiment. Our\npredicted, equilibrium lattice constant is 5.63 \\AA{}, with a corresponding\nindirect band gap of 0.65 eV and a bulk modulus of 80 GPa. We also calculated\nthe effective masses in various directions with respect to the $\\Gamma$ point.",
        "positive": "Parallelising Electrocatalytic Nitrogen Fixation Beyond\n  Heterointerfacial Boundary: The nitrogen (N2) reduction reaction (NRR) is an eco-friendly alternative to\nthe Haber-Bosch process to produce ammonia (NH3) with high sustainability.\nHowever, the significant magnitude of uphill energies in the multi-step NRR\npathways is a bottleneck of its serial reactions. Herein, the concept of a\nparallelized reaction is proposed to actively promote NH3 production via the\nNRR using a multi-phase vanadium oxide-nitride (V2O3/VN) hybrid system. Density\nfunctional theory calculations revealed that the V2O3/VN junction parallelizes\nNRR pathways by exchanging intermediate N2H4* and NH2* products to avoid\nmassive uphill energies towards final NH3 generation. Such an exchange is\ndriven by the difference in coverage of the two species. The impact of the\nreaction parallelization strategy for multi-step nitrogen reduction is\ndemonstrated with the V2O3/VN junction by an increased ammonia yield rate of\n18.36 micro mol h^-1 cm^-2 and a Faraday efficiency (FE) of 26.62% at -0.3 V\nversus a reversible hydrogen electrode in a 0.1 M aqueous KOH electrolyte, of\nwhich FE value exhibits 16.95 times and 6.22 times higher than that of\nsingle-phase V2O3 and VN, respectively. The introduction of multi-phase\noxides/nitrides into a transition metal-based electrocatalyst can thus be a\npromising approach to realizing an alternative method for N2 fixation."
    },
    {
        "anchor": "Multibeam Electron Diffraction: One of the primary uses for transmission electron microscopy (TEM) is to\nmeasure diffraction pattern images in order to determine a crystal structure\nand orientation. In nanobeam electron diffraction (NBED) we scan a moderately\nconverged electron probe over the sample to acquire thousands or even millions\nof sequential diffraction images, a technique that is especially appropriate\nfor polycrystalline samples. However, due to the large Ewald sphere of TEM,\nexcitation of Bragg peaks can be extremely sensitive to sample tilt, varying\nstrongly for even a few degrees of sample tilt for crystalline samples. In this\npaper, we present multibeam electron diffraction (MBED), where multiple probe\nforming apertures are used to create mutiple STEM probes, all of which interact\nwith the sample simultaneously. We detail designs for MBED experiments, and a\nmethod for using a focused ion beam (FIB) to produce MBED apertures. We show\nthe efficacy of the MBED technique for crystalline orientation mapping using\nboth simulations and proof-of-principle experiments. We also show how the\nangular information in MBED can be used to perform 3D tomographic\nreconstruction of samples without needing to tilt or scan the sample multiple\ntimes. Finally, we also discuss future opportunities for the MBED method.",
        "positive": "Ferroelectric transition of a chiral molecular crystal BINOL2DMSO: We report dielectric, thermodynamical, acoustic, and optical properties of a\nchiral molecular crystal, 1,1'-bi-2-naphthol 2-dimethylsulfoxide (BINOL2DMSO).\nWe find two successive phase transitions at Tc1=190 K and Tc2=125 K. The first\ntransition at Tc1 is characterized by an order-disorder transition of the guest\nmolecules DMSO along with ferroelectricity. At the second transition of Tc2,\nthe crystal structure deforms from tetragonal to monoclinic, leading to domain\nformation. Low-temperature x-ray diffraction suggests that the space group\nchanges from P4_12_12 (P4_32_12) to P4_1 (P4_3) at Tc1, and down to P112_1 at\nTc2."
    },
    {
        "anchor": "On the incompatibility of strains and its application to mesoscopic\n  studies of plasticity: Structural transitions are invariably affected by lattice distortions. If the\nbody is to remain crack-free, the strain field cannot be arbitrary but has to\nsatisfy the Saint-Venant compatibility constraint. Equivalently, an\nincompatibility constraint consistent with the actual dislocation network has\nto be satisfied in media with dislocations. This constraint can be incorporated\ninto strain-based free energy functionals to study the influence of\ndislocations on phase stability. We provide a systematic analysis of this\nconstraint in three dimensions and show how three incompatibility equations\naccommodate an arbitrary dislocation density. This approach allows the internal\nstress field to be calculated for an anisotropic material with spatially\ninhomogeneous microstructure and distribution of dislocations by minimizing the\nfree energy. This is illustrated by calculating the stress field of an edge\ndislocation and comparing it with that of an edge dislocation in an infinite\nisotropic medium. We outline how this procedure can be utilized to study the\ninteraction of plasticity with polarization and magnetization.",
        "positive": "Universal Design Methodology for Printable Microstructural Materials via\n  a New Deep Generative Learning Model: Application to a Piezocomposite: We devised a general heterogeneous microstructural design methodology applied\nto a specific material system, elasto-electro-active piezoelectric ceramic\nembedded plastics, which has great potential in sensing, 5G communication, and\nenergy harvesting. Due to the multiphysics interactions of the studied material\nsystem, we have developed an accurate and efficient FFT-based numerical method\nto find the multifunctional properties of diverse cellular microstructures\ngenerated by our HetMiGen code. To mine this big dataset, we used our\ncustomized physics-aware generative neural network in the format of a VAE with\nconvolutional neural layers augmented by a vision transformer to learn\nlong-distance features which may affect the properties of the 3D voxelized\nmicrostructures. In training, the decoder learns how to map the property\ndistribution to the appropriate high-dimensional distribution of 3D\nmicrostructures. Therefore, it can be considered an online material designer\nwithin the explored design space during its inference phase."
    },
    {
        "anchor": "Antiferromagnetic superexchange interactions in LaOFeAs: From first-principles calculations, we have studied the electronic and\nmagnetic structures of the ground state of LaOFeAs. The Fe spins are found to\nbe collinear antiferromagnetic ordered, resulting from the interplay between\nthe strong nearest and next-nearest neighbor superexchange antiferromagnetic\ninteractions. The structure transition observed by neutron scattering is shown\nto be magnetically driven. Our study suggests that the antiferromagnetic\nfluctuation plays an important role in the Fe-based superconductors. This sheds\nlight on the understanding of the pairing mechanism in these materials.",
        "positive": "Universal Faraday rotation in HgTe wells with critical thickness: The universal value of Faraday rotation angle close to the fine structure\nconstant is experimentally observed in thin HgTe quantum wells with thickness\non the border between trivial insulating and the topologically non-trivial\nDirac phases. The quantized value of the Faraday angle remains robust in the\nbroad range of magnetic fields and gate voltages. Dynamic Hall conductivity of\nthe hole-like carriers extracted from the analysis of the transmission data\nshows theoretically predicted universal value of consistent with the doubly\ndegenerate Dirac state. On shifting the Fermi level by the gate voltage the\neffective sign of the charge carriers changes from positive (holes) to negative\n(electrons). The electron-like part of the dynamic response does not show\nquantum plateaus and is well described within the classical Drude model."
    },
    {
        "anchor": "Tuning Dzyaloshinskii-Moriya Interaction in Ferrimagnetic GdCo: A First\n  Principles Approach: We present a systematic analysis of our ability to tune chiral\nDzyaloshinskii-Moriya Interactions (DMI) in compensated ferrimagnetic\nPt/GdCo/Pt1-xWx trilayers by cap layer composition. Using first principles\ncalculations, we show that the DMI increases rapidly for only ~ 10% W and\nsaturates thereafter, in agreement with experiments. The calculated DMI shows a\nspread in values around the experimental mean, depending on the atomic\nconfiguration of the cap layer interface. The saturation is attributed to the\nvanishing of spin orbit coupling energy at the cap layer and the simultaneous\nconstancy at the bottom interface. Additionally, we predict the DMI in\nPt/GdCo/X (X=Ta, W, Ir) and find that W in the cap layer favors a higher DMI\nthan Ta and Ir that can be attributed to the difference in d-band alignment\naround the Fermi level. Our results open up exciting combinatorial\npossibilities for controlling the DMI in ferrimagnets towards nucleating and\nmanipulating ultrasmall high-speed skyrmions.",
        "positive": "Correction of Density-Functional-Theory based polynomial interatomic\n  potentials to reproduce experimental melting properties: Recently, we developed a method to construct polynomial interatomic\npotentials from ab-initio calculations in order to accurately describe laser\nexcited solids [PRL 124, 085501 (2020)]. However, ab-initio methods, and\ntherefore analytical potentials derived from them, commonly do not provide an\naccurate prediction of the melting temperature. In order to reproduce the\nexperimental melting properties, but keeping the accuracy in the laser excited\ncase, we present here an approach to modify few key coefficients of polynomial\ninteratomic potentials constructed from ab-initio data. We show that, with the\nhelp of such corrections, the electronic-temperature dependent interatomic\npotential for silicon can, at the same time, describe nonthermal laser induced\neffects with ab-initio accuracy and also provide the correct experimental\nmelting temperature and slope $dT/dp$."
    },
    {
        "anchor": "Commercializing metal production in the modern era: The dominant feature of industrial development in the nineteenth century was\nthe use of power, but closely associated with it and of scarcely less\nimportance was the enormous increase in the use of metals made possible by\nmetallurgical progress. Here we review the development and use of three wonder\nmetals, and propose next-generation electrochemical cell designs for metal\nproduction.",
        "positive": "Machine Learning and Materials Informatics: Recent Applications and\n  Prospects: Propelled partly by the Materials Genome Initiative, and partly by the\nalgorithmic developments and the resounding successes of data-driven efforts in\nother domains, informatics strategies are beginning to take shape within\nmaterials science. These approaches lead to surrogate machine learning models\nthat enable rapid predictions based purely on past data rather than by direct\nexperimentation or by computations/simulations in which fundamental equations\nare explicitly solved. Data-centric informatics methods are becoming useful to\ndetermine material properties that are hard to measure or compute using\ntraditional methods--due to the cost, time or effort involved--but for which\nreliable data either already exists or can be generated for at least a subset\nof the critical cases. Predictions are typically interpolative, involving\nfingerprinting a material numerically first, and then following a mapping\n(established via a learning algorithm) between the fingerprint and the property\nof interest. Fingerprints may be of many types and scales, as dictated by the\napplication domain and needs. Predictions may also be extrapolative--extending\ninto new materials spaces--provided prediction uncertainties are properly taken\ninto account. This article attempts to provide an overview of some of the\nrecent successful data-driven \"materials informatics\" strategies undertaken in\nthe last decade, and identifies some challenges the community is facing and\nthose that should be overcome in the near future."
    },
    {
        "anchor": "Effect of edge vacancies on performance of planar graphene tunnel\n  field-effect transistor: The influence of edge vacancies on the working ability of the planar graphene\ntunnel field-effect transistor (TFET) is studied at various concentrations and\ndistributions (normal, uniform, periodic) of defects. All calculations are\nperformed by using the Green's function method and the tight-binding\napproximation. It is shown that the transistor performance depends critically\non two important factors associated with the defects: the destruction of the\nedge-localized electronic states and the emergence of subpeaks near the Fermi\nlevel. The supportable operation conditions of the TFET are found to be ensured\nat 30 percent or less of edge vacancies regardless of the type of their\ndistribution.",
        "positive": "Pattern Formation Mechanism of Directionally-Solidified MoSi2/Mo5Si3\n  Eutectic by Phase-Field Simulation: A phase-field study has been conducted to obtain an understanding of the\nformation mechanism of the script lamellar pattern of MoSi2/Mo5Si3 eutectic\ncomposite, which is a promising candidate for high-temperature structural\napplication. The spacing of the lamellar pattern in the simulation results\nshows good agreement with that of experimental observations and analytical\nsolutions under three growth rates: 10 mm/h, 50 mm/h, and 100 mm/h. The\ndiscontinuity of Mo5Si3 rods, in contrast to the regular eutectic with a\ncontinuous pattern, is claimed to be caused by the instability of the\nsolid-liquid interface. In this study, the implementation of Mo5Si3 nucleation\nover the solid-liquid interface has been proposed and successfully reproduced\nthe characteristic of discontinuity. A highly random and intersected lamellar\npattern similar to that observed in the ternary MoSi2/Mo5Si3 eutectic alloyed\nwith 0.1at% Co has been obtained in simulation owing to the increase in the\nfrequency of nucleation. In addition, it has been demonstrated that the\ninclination of the Mo5Si3 rod can be reproduced by taking into account the\nstrong relaxation of lattice strain energy, which is generally considered to be\nnegligible in eutectic reaction, as the result of the formation of\nledge-terrace structure."
    },
    {
        "anchor": "Topologically-protected metallic states induced by a one-dimensional\n  extended defect in a 2D topological insulator: We report ab initio calculations showing that a single one-dimensional\nextended defect can originate topologically-protected metallic states in the\nbulk of two-dimensional topological insulators. We find that a narrow extended\ndefect composed of periodic units consisting of one octogonal and two\npentagonal rings embedded in the hexagonal bulk of a bismuth bilayer introduces\ntwo pairs of one-dimensional Dirac-fermion states with opposite spin-momentum\nlocking. Although both Dirac pairs are localized along the extended-defect\ncore, their interactions are screened due to the trivial topological nature of\nthe extended defect.",
        "positive": "Simulation of ion track ranges in uranium oxide: Direct comparisons between statistically sound simulations of ion-tracks and\npublished experimental measurements of range densities of iodine implants in\nuranium dioxide have been made with implant energies in the range of 100-800\nkeV. Our simulations are conducted with REED-MD (Rare Event Enhanced\nDomain-following Molecular Dynamics) in order to account for the materials\nstructure in both single crystalline and polycrystalline experimental samples.\nWe find near-perfect agreement between REED-MD results and experiments for\npolycrystalline target materials."
    },
    {
        "anchor": "Atomic scale characterization of the nucleation and growth of SnO2\n  particles in oxidized CuSn alloys: The internal oxidation of Sn was investigated to understand the oxidation\nkinetics of monophase CuSn alloys. SnO2 particles were characterized by\nanalytical transmission electron microscopy. The orientation relationship\nbetween SnO2 and Cu was determined with a special emphasis on the atomic scale\nstructure of Cu/SnO2 interfaces (misfit dislocations and chemical structure).\nHabit planes with a pure oxygen plane terminating the SnO2 phase are greatly\nfavored and large misfits promote the growth of plate shaped precipitates.",
        "positive": "Consequences of breaking time reversal symmetry in LaSb: a resistivity\n  plateau and extreme magnetoresistance: Time reversal symmetry (TRS) protects the metallic surface modes of\ntopological insulators (TIs). The transport signature of robust metallic\nsurface modes of TIs is a plateau that arrests the exponential divergence of\nthe insulating bulk with decreasing temperature. This universal behavior is\nobserved in all TI candidates ranging from Bi2Te2Se to SmB6. Recently, several\ntopological semimetals (TSMs) have been found that exhibit extreme\nmagnetoresistance (XMR) and TI universal resistivity behavior revealed only\nwhen breaking TRS, a regime where TIs theoretically cease to exist. Among these\nnew materials, TaAs and NbP are nominated for Weyl semimetal due to their lack\nof inversion symmetry, Cd3As2 is nominated for Dirac semimetal due to its\nlinear band crossing at the Fermi level, and WTe2 is nominated for resonant\ncompensated semimetal due to its perfect electron-hole symmetry. Here we\nintroduce LaSb, a simple rock-salt structure material without broken inversion\nsymmetry, without perfect linear band crossing, and without perfect\nelectron-hole symmetry. Yet LaSb portrays all the exotic field induced\nbehaviors of the aforementioned semimetals in an archetypal fashion. It shows\n(a) the universal TI resistivity with a plateau at 15 K, revealed by a magnetic\nfield, (b) ultrahigh mobility of carriers in the plateau region, (c) quantum\noscillations with a non-trivial Berry phase, and (d) XMR of about one million\npercent at 9 tesla rivaled only by WTe2 and NbP. Due to its dramatic\nsimplicity, LaSb is the ideal model system to formulate a theoretical\nunderstanding of the exotic consequences of breaking TRS in TSMs."
    },
    {
        "anchor": "In-plane and out of plane magnetic properties in Ni46Co4Mn38Sb12 Heusler\n  alloys ribbons: Magnetic, magnetocaloric and exchange bias properties have been\nsystematically investigated in Ni46Co4Mn38Sb12 ribbon by applying magnetic\nfield along (IP) and perpendicular (OP) to the ribbon plane. From the\nthermo-magnetization curves, the sharpness of the martensitic transition is\nobserved to be nearly the same for both IP and OP ribbons. The thermomagnetic\nirreversibility region is found to be larger in the OP ribbon at 500 Oe,\nindicating that the magnetic anisotropy is larger in this case. The OP ribbon\nshows the Hopkinson maximum at 500 Oe, both for the FCC and ZFC modes. The\nmagnetization curve for IP ribbon shows a faster approach to saturation,\ncompared to the OP ribbon. Isothermal magnetic entropy change at 50 kOe has\nbeen found to be nearly same for both the ribbons. At 5 K the coercivity and\nexchange bias values are larger for the OP ribbon. Crystallographic texturing\nof the ribbons and its effect in the easy magnetization direction are found to\nbe the reason behind the differences between the two ribbons.",
        "positive": "Magnetotransport of La0.70ca0.3-xsrxmno3 (Ag): A Potential Room\n  Temperature Bolometer and Magnetic Sensor: Here we report the optimized magneto-transport properties of polycrystalline\nLa0.70Ca0.3-xSrxMnO3 and their composites with Ag. The optimization was carried\nout by varying the Sr and Ag contents simultaneously to achieve large\ntemperature coefficient of resistance (TCR) as well as low field\nmagneto-resistance (MR) at room temperature. Sharpest paramagnetic\n(PM)-ferromagnetic (FM) and insulator-metal (IM) transition is observed in the\nvicinity of the room temperature (TC=300 K=TIM) for the composition\nLa0.70Ca0.20Sr00.10MnO3:Ag0.20. Partial substitution of larger Sr2+ ions at the\nCa2+ ions sites controls the magnitude of the FM and IM transition\ntemperatures, while the Ag induces the desired sharpness in these transitions.\nFor the optimized composition, maximum TCR and MR are tuned to room temperature\n(300 K) with the former being as high as 9% and the later being 20 and 30\npercent at 5 and 10 kOe magnetic fields respectively. Such sharp single peak\n(TCR= 9 percent) at room temperature can be used for the bolometric and\ninfrared detector applications. The achievement of large TCR and low field MR\nat T~300K in polycrystalline samples is encouraging and we believe that further\nimprovements can be achieved in thin films, which, by virtue of their low\nconduction noise, are more suitable for device applications."
    },
    {
        "anchor": "Enabling atomic resolution in convergent beam EMCD measurements by the\n  use of patterned apertures: We give an experimental demonstration of two types of recently proposed\nventilator apertures which can be used to acquire electron magnetic circular\ndichroic (EMCD) signals in zone axis orientation with high spatial resolution.\nTo simplify the experimental procedures, we propose a third type of aperture\nand experimentally demonstrate the use of this modified ventilator aperture for\nthe case of multiple symmetries in the diffraction patterns. To show the\nfeasibility of the atomic resolution EMCD, EMCD signals are acquired for a\nrange of beam convergence angles. High quality EMCD signals with convergence\nangles corresponding to atomic resolution electron probes are obtained.",
        "positive": "An Intuitive and Exact Steady-State Electrodynamic Formalism for\n  Uniaxial Multilayered Structures: Normal Incidence: Exact expressions for all the steady-state fields (E, H, D, B) in uniaxial\nlinear media composed of an arbitrary number of layers having arbitrary\nthicknesses subjected to normal incidence are derived. Generic boundary\ncondition relations in terms of the surface wave impedance are applied at each\nsurface so that fields between any sequence of layers can be related by a\ncascaded multiplication of transfer functions. With the substitution of the\nappropriate surface wave impedance for the generic surface wave impedance,\nthese generic transfer functions can be made to represent any reflection or\ntransmission of a wave across any boundary. This formalism obviates the need to\nsolve a large set of equations or an infinite series of reflections and\ntransmissions, which has been the traditional approach in solving such\nproblems. A numerically robust exact expression for the power dissipating in\nany uniaxial layer is also provided. Examples of the analysis of multilayered\nsystems are given. Although the development is devoted to electromagnetic\nwaves, the methodology and expressions are transferable to acoustical waves,\nand to some extent, the quantum mechanical wave function."
    },
    {
        "anchor": "Controlled co-excitation of direct and indirect ultrafast\n  demagnetization in Co/Pd multilayer with large perpendicular magnetic\n  anisotropy: Ever since its discovery in 1996, ultrafast demagnetization has ignited\nimmense research interest due to its scientific rigor and technological\npotential. A flurry of recent theoretical and experimental investigations has\nproposed direct and indirect excitation processes in separate systems. However,\nit still lacks a unified mechanism and remains highly debatable. Here, for the\nfirst time, we demonstrate that instead of either direct or indirect\ninteraction, simultaneous and controlled excitation of both direct and indirect\nmechanisms of demagnetization are possible in a multilayers composed of\nrepeated Co/Pd bi-layers. Moreover, we were able to modulate demagnetization\ntime (from ~350 fs to ~750 fs) by fluence and thickness dependent indirect\nexcitation due to heat current flowing vertically downward from top layers,\nwhich is combined with an altogether different scenario of direct irradiation.\nFinally, by regulating the pump wavelength we could effectively control the\ncontribution of indirect process, which gives a confirmation to our\nunderstanding of the ultrafast demagnetization process.",
        "positive": "New interpretation of the origin of 2DEG states at the surface of\n  layered topological insulators: On the basis of relativistic ab-initio calculations we show that the driving\nmechanism of simultaneous emergence of parabolic and M-shaped 2D electron gas\n(2DEG) bands at the surface of layered topological insulators as well as\nRashba-splitting of the former states is an expansion of van der Waals (vdW)\nspacings caused by intercalation of metal atoms or residual gases. The\nexpansion of vdW spacings and emergence of the 2DEG states localized in the\n(sub)surface region are also accompanied by a relocation of the topological\nsurface state to the lower quintuple layers, that can explain the absence of\ninterband scattering found experimentally."
    },
    {
        "anchor": "Varying magnetism in the lattice distorted Y2NiIrO6 and La2NiIrO6: We investigate the electronic and magnetic properties of the newly\nsynthesized double perovskites Y$_{2}$NiIrO$_{6}$ and La$_{2}$NiIrO$_{6}$,\nusing density functional calculations, crystal field theory, superexchange\npictures, and Monte Carlo simulations. We find that both systems are\nantiferromagnetic (AFM) Mott insulators, with the high-spin Ni$^{2+}$\n$t_{2g}$$^{6}e_{g}$$^{2}$ ($S=1$) and the low-spin Ir$^{4+}$ $t_{2g}$$^{5}$\n($S=1/2$) configurations. We address that their lattice distortion induces\n$t_{2g}$-$e_{g}$ orbital mixing and thus enables the normal Ni$^{+}$-Ir$^{5+}$\ncharge excitation with the electron hopping from the Ir `$t_{2g}$' to Ni\n`$e_g$' orbitals, which promotes the AFM Ni$^{2+}$-Ir$^{4+}$ coupling.\nTherefore, the increasing $t_{2g}$-$e_{g}$ mixing accounts for the enhanced\n$T_{\\rm N}$ from the less distorted La$_{2}$NiIrO$_{6}$ to the more distorted\nY$_{2}$NiIrO$_{6}$. Moreover, our test calculations find that in the otherwise\nideally cubic Y$_{2}$NiIrO$_{6}$, the Ni$^{+}$-Ir$^{5+}$ charge excitation is\nforbidden, and only the abnormal Ni$^{3+}$-Ir$^{3+}$ excitation gives a weakly\nferromagnetic (FM) behavior. Furthermore, we find that owing to the crystal\nfield splitting, Hund exchange, and broad band formation in the highly\ncoordinated fcc sublattice, Ir$^{4+}$ ions are not in the $j_{\\rm eff}=1/2$\nstate but in the $S=1/2$ state carrying a finite orbital moment by spin-orbit\ncoupling (SOC). This work clarifies the varying magnetism in Y$_{2}$NiIrO$_{6}$\nand La$_{2}$NiIrO$_{6}$ associated with the lattice distortions.",
        "positive": "Influence of graphene on the electronic and magnetic properties of an\n  iron(III) porphyrin chloride complex: Although iron-based catalysts are regarded as a promising alternative to\nprecious metal catalysts, their precise electronic structures during catalysis\nstill pose challenges for computational descriptions. A particularly urgent\nquestion is the influence of the environment on the electronic structure, and\nhow to describe this properly with computational methods. Here, we study an\niron porphyrin chloride complex adsorbed on a graphene sheet using density\nfunctional theory calculations to detail how much the electronic structure is\ninfluenced by the presence of a graphene layer. Our results indicate that weak\ninteractions due to van der Waals forces dominate between the porphyrin complex\nand graphene, and only a small amount of charge is transferred between the two\nentities. Furthermore, the interplay of the ligand field environment, strong\n$p$ $-$ $d$ hybridization, and correlation effects within the complex are\nstrongly involved in determining the spin state of the iron ion. By bridging\nmolecular chemistry and solid state physics, this study provides first steps\ntowards a joint analysis of the properties of iron-based catalysts from first\nprinciples."
    },
    {
        "anchor": "Ferromagnetic Resonance in selected nanostructural materials designed\n  for technological applications: During the past ten years nanostructures have been subject of active\nresearch. Fabrication of such systems follows well developed methods. The\nincrease in the number of materials available for research and applications\nrequires that the methods of their characterization be even more precise then\nbefore. Thin film structures have many advantages for technological\napplications because of compatibility with integrated circuit design. The\nmagnetoimpedance, MI (change of impedance of a ferromagnet on application of a\nfield) in 3-layered structures consisting of two magnetic layers separated by a\nnon-magnetic conductive layer has been predicted to show high MI. In many cases\nthe experimental values of MI effect are smaller than the theoretical\npredictions. Therefore, more careful characterization of the samples is a must.\nAccordingly, the first part of the present research deals with a ferromagnetic\nresonance, FMR, study of thin films and multilayers containing Fe20Ni80 layered\nnanocomponents. The second system proposed for ferromagnetic resonance study\nconsists of Co/GdCo multilayers prepared by rf-sputtering. It was chosen as a\nmodel system both for convenience and in view of possible applications. The\nthird group of magnetic materials for FMR characterization consists of powders:\ncommercial polystyrene beads (Dynabeads-480) and CoNi powders with nanoscale\nparticle dimensions. These particles have many biomedical applications. FMR and\nmicrowave absorption in micron size powders have been studied previously. More\nrecently new methods of small particle fabrication have been developed.\nTherefore their characterization by microwave methods is highly desirable.",
        "positive": "Ab-initio electronic and magnetic structure in La_0.66Sr_0.33MnO_3:\n  strain and correlation effects: The effects of tetragonal strain on electronic and magnetic properties of\nstrontium-doped lanthanum manganite, La_{2/3}Sr_{1/3}MnO_3 (LSMO), are\ninvestigated by means of density-functional methods. As far as the structural\nproperties are concerned, the comparison between theory and experiments for\nLSMO strained on the most commonly used substrates, shows an overall good\nagreement: the slight overestimate (at most of 1-1.5 %) for the equilibrium\nout-of-plane lattice constants points to possible defects in real samples. The\ninclusion of a Hubbard-like contribution on the Mn d states, according to the\nso-called \"LSDA+U\" approach, is rather ineffective from the structural point of\nview, but much more important from the electronic and magnetic point of view.\nIn particular, full half-metallicity, which is missed within a bare\ndensity-functional approach, is recovered within LSDA+U, in agreement with\nexperiments. Moreover, the half-metallic behavior, particularly relevant for\nspin-injection purposes, is independent on the chosen substrate and is achieved\nfor all the considered in-plane lattice constants. More generally, strain\neffects are not seen to crucially affect the electronic structure: within the\nconsidered tetragonalization range, the minority gap is only slightly (i.e. by\nabout 0.1-0.2 eV) affected by a tensile or compressive strain. Nevertheless, we\nshow that the growth on a smaller in-plane lattice constant can stabilize the\nout-of-plane vs in-plane e_g orbital and significatively change their relative\noccupancy. Since e_g orbitals are key quantities for the double-exchange\nmechanism, strain effects are confirmed to be crucial for the resulting\nmagnetic coupling."
    },
    {
        "anchor": "Intervalence Plasmons in Boron-Doped Diamond: Doped semiconductors are capable of exhibiting metallic-like properties\nranging from superconductivity to tunable localized surface plasmon resonances.\nDiamond is a wide-bandgap semiconductor that is rendered electronically active\nby incorporating a hole dopant, boron. While the effects of boron doping on the\nelectronic band structure of diamond are well-studied, any link between charge\ncarriers and plasmons, which could facilitate optical applications, has never\nbeen shown. Here, we report intervalence plasmons in boron-doped diamond,\ndefined as collective electronic excitations between the valence subbands,\nopened up by the presence of holes. Evidence for these low energy excitations\nis provided by scanning transmission electron microscope-valence electron\nenergy loss spectroscopy and photoinduced force infrared spectroscopy. The\nmeasured loss and absorbance spectra are subsequently reproduced by\nfirst-principles calculations based on the contribution of intervalence band\ntransitions to the dielectric function. Remarkably, the calculations also\nreveal that the real part of the dielectric function exhibits a resonance\ncharacteristic of metallicity (narrow-banded negative values of the dielectric\nfunction). The energy of the zero-crossing and the position of the loss peak\nare found to coincide, and both increase with the carrier density. Our results\nprovide insight into a new mechanism for inducing plasmon-like behavior in\ndoped semiconductors from intervalence band transitions, and the possibility of\nattaining such properties in diamond, a key emerging material for biomedical\nand quantum information technologies.",
        "positive": "Tight-binding theory of spin-spin interactions, Curie temperatures, and\n  quantum Hall effects in topological (Hg,Cr)Te in comparison to\n  non-topological (Zn,Cr)Te, and (Ga,Mn)N: Earlier theoretical results on $p$-$d$ and $d$-$d$ exchange interactions for\nzinc-blende semiconductors with Cr$^{2{+}}$ and Mn$^{3{+}}$ ions are revisited\nand extended by including contributions beyond the dominating ferromagnetic\n(FM) superexchange term [i.e., the interband Bloembergen-Rowland-Van Vleck\ncontribution and antiferromagnetic (AFM) two-electron term], and applied to\ntopological Cr-doped HgTe and non-topological (Zn,Cr)Te and (Ga,Mn)N in\nzinc-blende and wurtzite crystallographic structures. From the obtained values\nof the $d$-$d$ exchange integrals $J_{ij}$, and by combining the Monte-Carlo\nsimulations with the percolation theory for randomly distributed magnetic ions,\nwe determine magnitudes of Curie temperatures $T_{\\text{C}}(x)$ for\n$\\mathrm{Zn}_{1-x}\\mathrm{Cr}_x\\mathrm{Te}$ and\n$\\mathrm{Ga}_{1-x}\\mathrm{Mn}_x\\mathrm{N}$ and compare to available\nexperimental data. Furthermore, we find that competition between FM and AFM\n$d$-$d$ interactions can lead to a spin-glass phase in the case of\n$\\mathrm{Hg}_{1-x}\\mathrm{Cr}_x\\mathrm{Te}$. This competition, along with a\nrelatively large magnitude of the AF $p$-$d$ exchange energy $N_0\\beta$ can\nstabilize the quantum spin Hall effect, but may require the application of a\ntilted magnetic field to observe the quantum anomalous Hall effect in HgTe\nquantum wells doped with Cr."
    },
    {
        "anchor": "Discrete Quantum Geometry and Intrinsic Spin Hall Effect: We show that the quantum geometry of the Fermi surface can be numerically\ndescribed by a 3-dimensional discrete quantum manifold. This approach not only\navoids singularities in the Fermi sea, but it also enables the precise\ncomputation of the intrinsic Hall conductivity resolved in spin, as well as any\nother local properties of the Fermi surface. The method assures numerical\naccuracy when the Fermi level is arbitrarily close to singularities, and it\nremains robust when Kramers degeneracy is protected by symmetry. The approach\nis demonstrated by calculating the anomalous Hall and spin Hall conductivities\nof a 2-band lattice model of a Weyl semimetal and a full-band ab-initio model\nof zincblende GaAs.",
        "positive": "Ferromagnetism below the Stoner limit in La-doped SrB_6: Spin-polarized band calculations for LaSr_7B_{48} show a weak ferro-magnetic\nstate. This is despite a low density-of-states (DOS) and a low Stoner factor.\nThe reason for the magnetic state is found to be associated with a gain in\npotential energy in addition to the exchange energy, as a spin-splitting is\nimposed. An impurity like La DOS is essential for this effect. It makes a\ncorrection to the Stoner factor, and provides an explanation of the recently\nobserved weak ferro-magnetism in doped hexaborides."
    },
    {
        "anchor": "Ferroelectricity promoted by cation/anion divacancies in SrMnO$_3$: We investigate the effect of polar Sr-O vacancy pairs on the electric\npolarization of SrMnO$_3$ (SMO) thin films using density functional theory\n(DFT) calculations. This is motivated by indications that ferroelectricity in\ncomplex oxides can be engineered by epitaxial strain but also \\textit{via} the\ndefect chemistry. Our results suggest that intrinsic doping by cation and anion\ndivacancies can induce a local polarization in unstrained non-polar SMO thin\nfilms and that a ferroelectric state can be stabilized below the critical\nstrain of the stoichiometric material. This polarity is promoted by the\nelectric dipole associated with the defect pair and its coupling to the atomic\nrelaxations upon defect formation that polarize a region around the defect.\nThis suggests that polar defect pairs affect the strain-dependent\nferroelectricity in semiconducting antiferromagnetic SMO. For metallic\nferromagnetic SMO we find a much weaker coupling between the defect dipole and\nthe polarization due to much stronger electronic screening. Coupling of\ndefect-pair dipoles at high enough concentrations along with their switchable\norientation thus makes them a promising route to affect the ferroelectric\ntransition in complex transition metal oxide thin films.",
        "positive": "Formation of a stable surface oxide in MnBi$_2$Te$_4$ thin films: Understanding the air-stability of MnBi$_2$Te$_4$ thin films is crucial for\nthe development and long-term operation of electronic devices based around\nmagnetic topological insulators. In the present work, we study MnBi$_2$Te$_4$\nthin films upon exposure to atmosphere using a combination of synchrotron-based\nphotoelectron spectroscopy, room temperature electrical transport and atomic\nforce microscopy to determine the oxidation process. After 2 days air exposure\na 2 nm thick oxide passivates the surface, corresponding to oxidation of only\nthe top two surface layers, with the underlying layers preserved. This\nprotective oxide layer results in samples that still exhibit metallic\nconduction even after several days air exposure. Furthermore, the work function\ndecreases from 4.4 eV for pristine MnBi$_2$Te$_4$ to 4.0 eV after the formation\nof the oxide, along with only a small shift in the core levels indicating\nminimal doping as a result of air exposure. With the oxide confined to the top\nsurface layers, and the underlying layers preserved, it may be possible to\nexplore new avenues in how to handle, prepare and passivate future\nMnBi$_2$Te$_4$ devices."
    },
    {
        "anchor": "Control of spin waves by spatially modulated strain: We suggest using spatially modulated strain for control of a spin wave\npropagating inside a bulk magnet. The modulation with the wave vector $q=2k$,\nby virtue of magnetoelasticity, mixes spin waves with wave vectors near $k$ and\n$-k$. This leads to lifting the degeneracy of the symmetric and antisymmetric\neigenstate combinations of these waves. The resulting picture reminds one of a\ntunneling particle in a symmetric double-well potential. Here, a moving spin\nwave being subjected to the $2k$-lattice modulation after some time alters its\npropagation direction to the opposite one, and so on. The effect can be\nutilized for the control of the spin-wave propagation that can be useful for\nspintronic and magnonic applications. The control may include a delay line\nelement, filtering, and waveguide of the spin waves.",
        "positive": "First principles study of the Si(557)-Au surface: We have performed a density functional study of fifteen different structural\nmodels of the Si(557)-Au surface reconstruction. Here we present a brief\nsummary of the main structural trends obtained for the more favourable models,\nfocusing afterwards in a detailed description of the atomic structure,\nelectronic properties and, simulated STM images of the most stable model\npredicted by our calculations. This structure is in very good agreement with\nthat recently proposed from X-ray diffraction measurements by Robinson et al.\n[Phys. Rev. Lett. 88, (2002) 096194]."
    },
    {
        "anchor": "Electrical contact properties between Yb and few-layer WS$_2$: Charge injection mechanism from contact electrodes into two-dimensional (2D)\ndichalcogenides is an essential topic for exploiting electronics based on 2D\nchannels, but remains not well understood. Here, low-work-function metal\nytterbium (Yb) was employed as contacts for tungsten disulfide (WS$_2$) to\nunderstand the realistic injection mechanism. The contact properties in WS$_2$\nwith variable temperature (T) and channel thickness (tch) were synergetically\ncharacterized. It is found that the Yb/WS$_2$ interfaces exhibit a strong\npinning effect between energy levels and a low contact resistance ($R_\\rm{C}$)\nvalue down to $5\\,k\\Omega\\cdot\\mu$m. Cryogenic electrical measurements reveal\nthat $R_\\rm{C}$ exhibits weakly positive dependence on T till 77 K, as well as\na weakly negative correlation with tch. In contrast to the non-negligible\n$R_\\rm{C}$ values extracted, an unexpectedly low effective thermal injection\nbarrier of 36 meV is estimated, indicating the presence of significant\ntunneling injection in subthreshold regime and the inapplicability of the pure\nthermionic emission model to estimate the height of injection barrier.",
        "positive": "Nanocrystalline FeCr alloys synthesised by severe plastic deformation --\n  a potential material for exchange bias and enhanced magnetostriction: This work gives insights into processing and characterisation of bulk\nnanocrystalline FeCr materials. The investigated FeCr alloys, consisting of 30,\n50 and 70 at.% ferromagnetic Fe and remaining anti-ferromagnetic Cr, are\nprocessed by arc melting and subsequent severe plastic deformation by high\npressure torsion. The physical similarities between elemental Fe and Cr in\ncombination with the nanocrystalline structure of the as-deformed alloys,\nnecessitates advanced characterisation techniques for the as-deformed state:\nIn-situ annealing synchrotron X-ray diffraction measurements as well as\nelectron microscopy experiments are linked to magnetostrictive measurements and\nreveal a single phase microstructure. Surprisingly, the nanocrystalline FeCr\nalloys remain supersaturated solid solutions upon annealing above 500{\\deg}C,\nmeaning a decomposition in a FeCr nanocomposite is suppressed. For the chosen\nannealing conditions grain growth is faster than decomposition and enhanced\nmagnetostrictive values are found compared to materials in the as-deformed\nstate."
    },
    {
        "anchor": "Magnetic, electrochemical and thermoelectric properties of $P2 -\n  Na_x(Co_{7/8}Sb_{1/8})O_2$: We theoretically investigated the electronic, electrochemical and magnetic\nproperties of Sb doped $Na_xCoO_2$ ($x = 1, 0.75$ and $0.50$). $Sb_{Co}$\ndopants adopt +5 oxidation state in $Na_xCoO_2$ host lattice for all Na\nconcentrations ($x$). Due to high oxidation states, $Sb^{5+}$ strongly repels\nNa ions and therefore it decreases the electrochemical potential (vs.\nNa/Na$^+$). The electrons introduced by $Sb^{5+}$ localize on nearby Co ions\ncreating $Co^{2+}$ species which are absent in undoped $Na_xCoO_2$. $Co^{2+}$\nions reduce the spin entropy flow decreasing the Seebeck coefficient in the Sb\ndoped compounds. The results can be generalized to other dopants with high\noxidation state.",
        "positive": "Impact of magnetization and hyperfine field distribution on high\n  magnetoelectric coupling strength in BaTiO$_3$-BiFeO$_3$ multilayers: Understanding the mechanisms of magnetoelectric (ME) coupling within\nmultiferroic structures is paramount from a fundamental as well as an applied\npoint of view. We report here that the magnetoelectric properties, as well as\nthe magnetization, of BaTiO$_3$-BiFeO$_3$ superlattices can be tuned by varying\nthe BiFeO$_3$ layer thickness. The magnetoelectric voltage coefficient\n($\\alpha_{ME}$) reaches its maximum of 60.2 Vcm$^{-1}$Oe$^{-1}$ at 300 K, one\nof the highest values reported so far, for a sample with a BiFeO$_3$ thickness\nof 5 nm and a BaTiO$_3$ thickness of 10 nm. To gain deeper insight into the\nincreased magnetoelectric coupling, and both the local and macroscopic magnetic\nproperties, samples with varying BiFeO$_3$ thicknesses have been investigated.\nCorrelations were established between the hyperfine field (HFF), the\nmagnetoelectric voltage coefficient and the magnetization. The possible\nmechanisms responsible for the strong magnetoelectric coupling are discussed."
    },
    {
        "anchor": "Critical magnetization behaviors of the triangular and Kagome lattice\n  quantum antiferromagnets: We investigate the $S=1/2$ quantum spin antiferromagnets on the triangular\nand Kagome lattices in magnetic field, using the numerical exact\ndiagonalization. Particularly we focus on an anomalous magnetization behavior\nof each system at 1/3 of the saturation magnetization. The critical exponent\nanalyses suggest that it is a conventional magnetization plateau on the\ntriangular lattice, while an unconventional phenomenon, called the\nmagnetization ramp, on the Kagome lattice.",
        "positive": "Accurate first principles detailed balance determination of Auger\n  recombination and impact ionization rates in semiconductors: The technologically important problem of predicting Auger recombination\nlifetimes in semiconductors is addressed by means of a fully first--principles\nformalism. The calculations employ highly precise energy bands and wave\nfunctions provided by the full--potential linearized augmented plane wave\n(FLAPW) code based on the screened exchange local density approximation. The\nminority carrier Auger lifetime is determined by two closely related\napproaches: \\emph{i}) a direct evaluation of the Auger rates within Fermi's\nGolden Rule, and \\emph{ii}) an indirect evaluation, based on a detailed balance\nformulation combining Auger recombination and its inverse process, impact\nionization, in a unified framework. Calculated carrier lifetimes determined\nwith the direct and indirect methods show excellent consistency \\emph{i})\nbetween them for $n$-doped GaAs and \\emph{ii}%) with measured values for GaAs\nand InGaAs. This demonstrates the validity and accuracy of the computational\nformalism for the Auger lifetime and indicates a new sensitive tool for\npossible use in materials performance optimization."
    },
    {
        "anchor": "Ultrafast Epitaxial Growth of Metre-Sized Single-Crystal Graphene on\n  Industrial Cu Foil: A foundation of the modern technology that uses single-crystal silicon has\nbeen the growth of high-quality single-crystal Si ingots with diameters up to\n12 inches or larger. For many applications of graphene, large-area high-quality\n(ideally of single-crystal) material will be enabling. Since the first growth\non copper foil a decade ago, inch-sized single-crystal graphene has been\nachieved. We present here the growth, in 20 minutes, of a graphene film of 5 x\n50 cm2 dimension with > 99% ultra-highly oriented grains. This growth was\nachieved by: (i) synthesis of sub-metre-sized single-crystal Cu(111) foil as\nsubstrate; (ii) epitaxial growth of graphene islands on the Cu(111) surface;\n(iii) seamless merging of such graphene islands into a graphene film with high\nsingle crystallinity and (iv) the ultrafast growth of graphene film. These\nachievements were realized by a temperature-driven annealing technique to\nproduce single-crystal Cu(111) from industrial polycrystalline Cu foil and the\nmarvellous effects of a continuous oxygen supply from an adjacent oxide. The\nas-synthesized graphene film, with very few misoriented grains (if any), has a\nmobility up to ~ 23,000 cm2V-1s-1 at 4 K and room temperature sheet resistance\nof ~ 230 ohm/square. It is very likely that this approach can be scaled up to\nachieve exceptionally large and high-quality graphene films with single\ncrystallinity, and thus realize various industrial-level applications at a low\ncost.",
        "positive": "Absorption kinetics of vacancies by cavities in Aluminum: numerical\n  characterization of sink strengths and first-passage statistics through\n  Krylov subspace projection and eigenvalue deflation: Modeling the microstructural evolution of metal and alloys, specifically\nunder irradiation, is essential to predict the aging properties of materials.\nMany models are based on a transition rate matrix describing the jump\nfrequencies of defects and involve a master equation governing the time\nevolution of a state probability vector. Here, we present non-stochastic\nnumerical techniques to characterize the motion of individual defects migrating\nover long distances prior to recombining or being absorbed by another defect,\nresorting to the theory of absorbing Markov chains. These important events are\nfully determined by their first-passage time distribution to distant locations,\nno-passage distribution ,and walker fluxes to the sinks. We show that these\nfunctions can be efficiently computed using a method combining Krylov subspace\nprojection and eigenvalue deflation. For a model system describing the\nabsorption of a vacancy by a cavity in aluminum, the use of a small Krylov\nsubspace deflated by the unique eigenmode corresponding to the quasi-stationary\ndistribution is sufficient to capture the kinetics of the defect absorption\nfaithfully. This method can be used in kinetic Monte Carlo simulations to\nperform stochastic non-local moves or in cluster dynamics simulations to\ncompute sink strengths."
    },
    {
        "anchor": "Orbital frustration at the origin of the magnetic behavior in LiNiO2: We report on the ESR, magnetization and magnetic susceptibility measurements\nperformed over a large temperature range, from 1.5 to 750 K, on high-quality\nstoichiometric LiNiO2. We find that this compound displays two distinct\ntemperature regions where its magnetic behavior is anomalous. With the help of\na statistical model based on the Kugel'-Khomskii Hamiltonian, we show that\nbelow T_of ~ 400 K, an orbitally-frustrated state characteristic of the\ntriangular lattice is established. This then gives a solution to the\nlong-standing controversial problem of the magnetic behavior in LiNiO2.",
        "positive": "Restricted three body problems at the nanoscale: In this paper, we investigate some of the classical restricted three body\nproblems at the nanoscale, such as the circular planar restricted problem for\nthree C60 fullerenes, and a carbon atom and two C60 fullerenes. We model the\nvan der Waals forces between the fullerenes by the Lennard-Jones potential. In\nparticular, the pairwise potential energies between the carbon atoms on the\nfullerenes are approximated by the continuous approach, so that the total\nmolecular energy between two fullerenes can be determined analytically. Since\nwe assume that such interactions between the molecules occur at sufficiently\nlarge distance, the classical three body problems analysis is legitimate to\ndetermine the collective angular velocity of the two and three C60 fullerenes\nat the nanoscale. We find that the maximum angular frequency of the two and\nthree fullerenes systems reach the terahertz range and we determine the\nstationary points and the points which have maximum velocity for the carbon\natom for the carbon atom and the two fullerenes system."
    },
    {
        "anchor": "Picosecond pump pulses probe the relevance of a laser-induced\n  electron-phonon non-equilibrium for the phase transition in FeRh: We use ultrafast x-ray diffraction to examine the impact of an\nelectron-phonon non-equilibrium on the kinetics of the\nantiferromagnetic-to-ferromagnetic phase transition in FeRh parameterized by\nthe structural response. By increasing the pump-pulse duration up to\n$10.5\\,\\text{ps}$, we suppressed the non-equilibrium between electrons and\nphonons present upon femtosecond laser excitation. However, independently of\nthe pump pulse duration, we find a nucleation of ferromagnetic domains on an\n$8\\,\\text{ps}$ timescale that starts as soon as the successively deposited\nenergy surpasses the site-specific threshold energy. Due to this threshold\nbehaviour the phase transition proceeds considerably faster than predicted by a\nconvolution of the dynamics observed for ultrafast excitation with the long\npump pulse duration. This makes long pump pulses generally useful to identify\nthe role of laser-induced non-equilibria and the non-linear threshold behavior\nof first-order phase transitions.",
        "positive": "Manipulation of magnetic domain wall by ferroelectric switching: Dynamic\n  magnetoelectricity at the nanoscale: Controlling magnetism using voltage is highly desired for applications, but\nremains challenging due to fundamental contradiction between polarity and\nmagnetism. Here we propose a mechanism to manipulate magnetic domain walls in\nferrimagnetic or ferromagnetic multiferroics using electric field. Different\nfrom those studies based on static domain-level couplings, here the\nmagnetoelectric coupling relies on the collaborative spin dynamics around\ndomain walls. Accompanying the reversal of spin chirality driven by\npolarization switching, a \"rolling-downhill\"-like motion of domain wall is\nachieved at the nanoscale, which tunes the magnetization locally. Our mechanism\nopens an alternative route to pursuit practical and fast converse\nmagnetoelectric functions via spin dynamics."
    },
    {
        "anchor": "Off-resonant all-optical switching dynamics in a ferromagnetic model\n  system: We present a theoretical study of the the effects of off-resonant polarized\noptical fields on a ferromagnetic model system. We determine the light-induced\ndynamics of itinerant carriers in a system that includes magnetism at the\nmean-field level and spin-orbit coupling. We investigate an all-optical\nswitching process for ferromagnets, which is close to the one proposed by\nQaiumzadeh et al. [Phys. Rev. B 88, 064416] for the inverse Faraday effect. By\ncomputing the optically driven coherent dynamics together with incoherent\nscattering mechanisms we go beyond a perturbation expansion in powers of the\noptical field. We find an important contribution of a dynamic Stark effect\ncoupling of the Raman type between the magnetic bands, which leads to a\npolarization-dependent effect on the magnetization that may support or oppose\nswitching, but also contributes to demagnetization via an increase in\nelectronic energy.",
        "positive": "Tunable ferroelectricity in oxygen-deficient perovskites: Using first-principles calculations, we predict that tunable ferroelectricity\ncan be realized in oxide perovskites with the Grenier structure and ordered\noxygen vacancies. Specifically, we show that\n$R_{1/3}A_{2/3}\\mathrm{FeO}_{2.67}$ solids (where $R$ is a rare-earth ion and\n$A$ an alkaline-earth cation) exhibit stable polar phases, with a spontaneous\npolarization tunable by an appropriate choice of $R$ and $A$. We find that\nlarger cations combined with small $R$ elements lead to a maximum in the\npolarization and to a minimum in the energy barriers required to switch the\nsign of the polarization. Ferroelectricity arises from cooperative distortions\nof octahedral and tetrahedral units, where a combination of rotational and\nsliding modes controls the emergence of polarization within three-dimensional\nconnected layers. Our results indicate that polar Grenier phases of oxide\nperovskites are promising materials for microelectronic applications and, in\ngeneral, for the study of phenomena emerging from breaking inversion symmetry\nin solids."
    },
    {
        "anchor": "Multiscale modelling in nuclear ferritic steels: from nano-sized defects\n  to embrittlement: Radiation-induced embrittlement of nuclear steels is one of the main limiting\nfactors for safe long-term operation of nuclear power plants. In support of\naccurate and safe reactor pressure vessel (RPV) lifetime assessments, we\ndeveloped a physics-based model that predicts RPV steel hardening and\nsubsequent embrittlement as a consequence of the formation of nano-sized\nclusters of minor alloying elements. This model is shown to provide reliable\nassessments of embrittlement for a very wide range of materials, with higher\naccuracy than industrial correlations. The core of our model is a multiscale\nmodelling tool that predicts the kinetics of solute clustering, given the steel\nchemical composition and its irradiation conditions. It is based on the\nobservation that the formation of solute clusters ensues from atomic transport\ndriven by radiation-induced mechanisms, differently from classical\nnucleation-and-growth theories. We then show that the predicted information\nabout solute clustering can be translated into a reliable estimate for\nradiation-induced embrittlement, via standard hardening laws based on the\ndispersed barrier model. We demonstrate the validity of our approach by\napplying it to hundreds of nuclear reactors vessels from all over the world.",
        "positive": "Modellization of hydraulic fracturing of porous materials: We review microstructural fracture growth models suitable for the study of\nhydraulic fracture processes in disordered porous materials and present some\nbasic results. It is shown that microstructural models exhibit certain\nsimilarities to corresponding theories of continua. These similarities are most\neasily demonstrated for simple crack geometries, i.e., straight cracks (finite\nsize scalings). However, there exist even scaling relations which are\ncompletely independent of the particular employed crack structure. Furthermore\nit is demonstrated that disorder in cohesional/flow properties can influence\nthe crack growth and the resulting fracture geometry in an essential way."
    },
    {
        "anchor": "Flexible, solid electrolyte-based lithium battery composed of LiFePO4\n  cathode and Li4Ti5O10 anode for applications in smart textiles: Here we report fabrication of flexible and stretchable battery composed of\nstrain free LiFePO4 cathode, Li4Ti5O10 anode and a solid poly ethylene oxide\n(PEO) electrolyte as a separator layer. The battery is developed in a view of\nsmart textile applications. Featuring solid thermoplastic electrolyte as a key\nenabling element this battery is potentially extrudable or drawable into fibers\nor thin stripes which are directly compatible with the weaving process used in\nsmart textile fabrication. The paper first details the choice of materials,\nfabrication and characterisation of electrodes and a separator layer. Then the\nbattery is assembled and characterised, and finally, a large battery sample\nmade of several long strips is woven into a textile, connectorized with\nconductive threads, and characterised. Within this paper, there are two\npractical aspects of battery design that we have investigated in details: first\nis making composites of cathode/anode material with optimized ratio of\nconducting carbon and polymer binder material, and second is battery\nperformance including cycling, reversibility, and compatibility of the\ncathode/anode materials. Finally, when casting electrodes and separator layer\nwe mostly focused on using aqueous solutions instead of organic solvents in\norder to make the fabrication process environmentally friendly.",
        "positive": "Strain-dependent local empirical pseudopotentials for lattice mismatched\n  III-V semiconductors, their alloys, heterostructures and nanostructures: For the latest EPM potentials, please see appendix A in Physical Review B,\n59, 15270 (1999)"
    },
    {
        "anchor": "High-Temperature Ferromagnetic Semiconductors: Janus Monolayer Vanadium\n  Trihalides: Two-dimensional (2D) intrinsic ferromagnetic semiconductors are expected to\nstand out in the spintronic field. Recently, the monolayer VI$_{3}$ has been\nexperimentally synthesized but the weak ferromagnetism and low Curie\ntemperature ($T_C$) limit its potential application. Here we report that the\nJanus structure can elevate the $T_C$ to 240 K. And it is discussed that the\nreason for high $T_C$ in Janus structure originates from the lower virtual\nexchange gap between $t_{2g}$ and $e_{g}$ states of nearest-neighbor V atoms.\nBesides, $T_C$ can be further substantially enhanced by tensile strain due to\nthe increasing ferromagnetism driven by rapidly quenched direct exchange\ninteraction. Our work supports a feasible approach to enhance Curie temperature\nof monolayer VI$_{3}$ and unveils novel stable intrinsic FM semiconductors for\nrealistic applications in spintronics.",
        "positive": "Anomalous lattice thermal conductivity in layered materials MNCl (M=Zr,\n  Hf) driven by the lanthanide contraction: High performance thermoelectric devices requires materials with low lattice\nthermal conductivities. Many strategies, such as phonon engineering, have been\nmade to reduce lattice thermal conductivity without simultaneously decrease of\nthe charge transport performance. It is a simple and effective approach to use\nmaterials with heavy element to reduce the lattice thermal conductivity. Here,\nbased on the first-principles calculations and phonon Boltzmann transport\nequations, we find the replacement of Zr with heavy element Hf in ZrNCl doesn't\nreduce the lattice thermal conductivity, instead, it surprisingly increases by\nabout 4 times at 300K. This unusual lattice thermal conductivity is mainly\nattributed to the dramatic enhancement in phonon lifetimes in Hf compound,\noriginating from the strong interatomic bonding due to lanthanide contraction.\nOur findings unveil the microscopic mechanisms of high thermal transport\nproperties in materials with heavy element, providing an alternative strategy\nin materials design with low lattice thermal conductivity for thermoelectric\napplications such as power restoration and generation."
    },
    {
        "anchor": "Atomistic Study of the Electronic Contact Resistivity Between the\n  Half-Heusler Alloys (HfCoSb, HfZrCoSb, HfZrNiSn) and the Metal Ag: Half-Heusler(HH) alloys have shown promising thermoelectric properties in the\nmedium and high temperature range. To harness these material properties for\nthermoelectric applications, it is important to realize electrical contacts\nwith low electrical contact resistivity. However, little is known about the\ndetailed structural and electronic properties of such contacts, and the\nexpected values of contact resistivity. Here, we employ atomistic ab initio\ncalculations to study electrical contacts in a subclass of HH alloys consisting\nof the compounds HfCoSb, HfZrCoSb, and HfZrNiSn. By using Ag as a prototypical\nmetal, we show that the termination of the HH material critically determines\nthe presence or absence of strong deformations at the interface. Our study\nincludes contacts to doped materials, and the results indicate that the p-type\nmaterials generally form ohmic contacts while the n-type materials have a small\nSchottky barrier. We calculate the temperature dependence of the contact\nresistivity in the low to medium temperature range and provide quantitative\nvalues that set lower limits for these systems.",
        "positive": "Single-Valley Engineering in Graphene Superlattices: The two inequivalent valleys in graphene preclude the protection against\ninter-valley scattering offered by an odd-number of Dirac cones characteristic\nof Z2 topological insulator phases. Here we propose a way to engineer a chiral\nsingle-valley metallic phase with quadratic crossover in a honeycomb lattice\nthrough tailored \\sqrt{3}N *\\sqrt{3}N or 3N *3N superlattices. The possibility\nof tuning valley-polarization via pseudo-Zeeman field and the emergence of\nDresselhaus-type valley-orbit coupling are proposed in adatom decorated\ngraphene superlattices. Such valley manipulation mechanisms and metallic phase\ncan also find applications in honeycomb photonic crystals."
    },
    {
        "anchor": "Absence of halfmetallicity in defect-free Cr, Mn-delta-doped Digital\n  Magnetic Heterostructures: We present results of a combined density functional and many-body\ncalculations for the electronic and magnetic properties of the defect-free\ndigital ferromagnetic heterostructures obtained by doping GaAs with Cr and Mn.\nWhile local density approximation/(+U) predicts half-metallicity in these\ndefect-free delta-doped heterostructures, we demonstrate that local many-body\ncorrelations captured by Dynamical Mean Field Theory induce within the minority\nspin channel non-quasiparticle states just above $E_F$. As a consequence of the\nexistence of these many-body states the half-metallic gap is closed and the\ncarriers spin polarization is significantly reduced. Below the Fermi level the\nminority spin highest valence states are found to localize more on the GaAs\nlayers being independent of the type of electronic correlations considered.\nThus, our results confirm the confinement of carriers in these delta-doped\nheterostructures, having a spin-polarization that follow a different\ntemperature dependence than magnetization. We suggest that polarized\nhot-electron photoluminescence experiments might bring evidence for the\nexistence of many-body states within the minority spin channel and their finite\ntemperature behavior.",
        "positive": "First-principles Nonadiabatic Dynamics of Molecules at Metal Surfaces\n  with Vibrationally Coupled Electron Transfer: Accurate description of nonadiabatic dynamics of molecules at metal surfaces\ninvolving electron transfer has been a longstanding challenge for theory. Here,\nwe tackle this problem by first constructing high-dimensional neural network\ndiabatic potentials including state crossings determined by constrained density\nfunctional theory, then applying mixed quantum-classical surface hopping\nsimulations to evolve coupled electron-nuclear motion. Our approach accurately\ndescribes the nonadiabatic effects in CO scattering from Au(111) without\nempirical parameters and yields results agreeing well with experiments under\nvarious conditions for this benchmark system. We find that both adiabatic and\nnonadiabatic energy loss channels have important contributions to the\nvibrational relaxation of highly vibrationally excited CO(vi = 17), whereas\nrelaxation of low vibrationally excited states of CO(vi = 2) is weak and\ndominated by nonadiabatic energy loss. The presented approach paves the way for\naccurate first-principles simulations of electron transfer mediated\nnonadiabatic dynamics at metal surfaces."
    },
    {
        "anchor": "Thermodynamic model of solute site preferences in ordered alloys: A thermodynamic model based on the law of mass action is used to calculate\nconcentrations of elementary point defects and to determine site preferences of\nsolute atoms in ordered alloys. Combinations of lattice vacancies, antisite\natoms and host interstitials that form equilibrium defects are enumerated for\nthe CsCl (B2) and Ni2Al3 structures. For CsCl, in addition to the two\nsubstitutional sites, a distorted tetrahedral interstitial site is considered.\nFor Ni2Al3, the Ni site, two distinct Al sites and a vacant, insterstitial-type\nNi-site are considered. An equation of constraint among concentrations of\nelementary defects is derived that is valid for any crystal structure. The\nconcentration of a selected defect can be solved using the equation of\nconstraint in conjunction with mass-action equations for defect combinations.\nThe method leads directly to defect concentrations without the need to evaluate\ncomposition-dependent chemical potentials, resulting in a more transparent\nformalism.\n  The model is used to explore the phenomenology of site-preferences of dilute\nternary solute atoms. Findings are in agreement with previous treatments\nrestricted to substitutional sites. General rules for how site-preferences\ndepend on temperature and on composition in non-stoichiometric compounds are\nobtained through algebraic analysis and numerical simulations: (1) Solute S\ntends to occupy substitutional sites of the element in which there is a\ndeficiency. (2) If the difference of energies of S on sites A and B is very\npositive or negative, then S will occupy site B or A exclusively, independent\nof composition. If the difference of site energies is intermediate, the solute\nwill switch from one site to the other as the composition changes. (3) Solutes\nhave a tendency to occupy interstitial or empty-lattice sites with a maximum\nsite-fraction near the stoichiometric composition.",
        "positive": "In-Situ Growth of Graphene on Hexagonal Boron Nitride for Electronic\n  Transport Applications: Transferring graphene flakes onto hexagonal boron nitride (h-BN) has been the\nmost popular approach for the fabrication of graphne/h-BN heterostructures so\nfar. The orientation between graphene and h-BN lattices, however, are not\ncontrollable and the h-BN/graphene interfaces are prone to be contaminated\nduring this elaborate process. Direct synthesis of graphene on h-BN is an\nalternative and rapidly growing approach. Synthesized graphene via such\napproaches is personally tailored to conform to each specific h-BN flakes,\nhence the limitations of conventional fabrication approaches are overcome.\nReported processes paved the initial steps to improve the scalablity of the\ndevice fabrication for industrial applications. Reviewing the developments in\nthe field, from the birth point to the current status is the focus of this\nletter. We show how the field has been developed to overcome the existing\nchallenges one after the other and discuss where the field is heading to."
    },
    {
        "anchor": "Ground state of the U2Mo compound: Physical properties of the\n  Omega-phase: Using ab initio calculations, unexpected structural instability was recently\nfound in the ground state of the U$_2$Mo compound. Instead of the unstable\n$I4/mmm$ structure, in this work the $P6/mmm$ ($\\# 191$) space group, usually\ncalled $\\Omega$-phase, is proposed as the fundamental state. Electronic and\nelastic properties are studied in this work in order to characterize the\nphysical properties of the new ground state. The stability of the\n$\\Omega$-phase is studied by means of its elastic constants calculation and\nphonon dispersion spectrum. Analysis of isotropic indices shows that the new\nphase is a ductile material with a minimal degree of anisotropy, suggesting\nthat U$_2$Mo in the $P6/mmm$ structure is an elastic isotropic material.\nAnalysis of charge density, density of electronic states (DOS) and the\ncharacter of the bands revealed a high level of hybridization between\n$d$-molybdenum electronic states and $d$- and $f$-uranium ones.",
        "positive": "Frequency-dependent substrate screening of excitons in atomically thin\n  transition metal dichalcogenide semiconductors: Atomically thin layers of transition metal dichalcogenides (TMDCs) exhibit\nexceptionally strong Coulomb interaction between charge carriers due to the\ntwo-dimensional carrier confinement in connection with weak dielectric\nscreening. The van der Waals nature of interlayer coupling makes it easy to\nintegrate TMDC layers into heterostructures with different dielectric or\nmetallic substrates. This allows to tailor electronic and optical properties of\nthese materials, as Coulomb interaction inside atomically thin layers is very\nsusceptible to screening by the environment. Here we theoretically investigate\ndynamical screening effects in TMDCs due to bulk substrates doped with carriers\nover a large density range, thereby offering three-dimensional plasmons as\ntunable degree of freedom. We report a wide compensation of renormalization\neffects leading to a spectrally more stable exciton than predicted for static\nsubstrate screening, even if plasmons and excitons are in resonance. We also\nfind a nontrivial dependence of the single-particle band gap on substrate\ndoping density due to dynamical screening. Our investigation provides\nmicroscopic insight into the mechanisms that allow for manipulations of TMDC\nexcitons by means of arbitrary plasmonic environments on the nanoscale."
    },
    {
        "anchor": "Fully self-consistent GW calculations for atoms and molecules: We solve the Dyson equation for atoms and diatomic molecules within the GW\napproximation, in order to elucidate the effects of self-consistency on the\ntotal energies and ionization potentials. We find GW to produce accurate energy\ndifferences although the self-consistent total energies differ significantly\nfrom the exact values. Total energies obtained from the Luttinger-Ward\nfunctional E_LW[G] with simple, approximate Green functions as input, are shown\nto be in excellent agreement with the self-consistent results. This\ndemonstrates that the Luttinger-Ward functional is a reliable method for\ntesting the merits of different self-energy approximations without the need to\nsolve the Dyson equation self-consistently. Self-consistent GW ionization\npotentials are calculated from the Extended Koopmans Theorem, and shown to be\nin good agreement with the experimental results. We also find the\nself-consistent ionization potentials to be often better than the\nnon-self-consistent G0W0 values. We conclude that GW calculations should be\ndone self-consistently in order to obtain physically meaningful and unambiguous\nenergy differences.",
        "positive": "Two Lifshitz points in melt-crystallized polymers: nanostructure,\n  necking, energy dissipation: In frameworks of scaling theory of phase transitions and critical phenomena\nthe structure of melt-crystallized polymers is discussed. The model constructed\nfollows drawing polymeric materials and dissipating the energy during the\ntransition from isotropic to oriented state. It is possible to estimate\ntemperatures of secondary relaxation transitions. The entropic parameters of\nthe model are: the space dimension; the number of components of an ordering\nfield; the polymerization degree. The Kuhn segment, the melting temperature and\nthe difference of energies of two rotating isomers can be regarded as energetic\nparameters. The model enables to calculate a number of important structural and\ndynamic physical values: the density ratio of crystalline to amorphous phase;\nthe thicknesses of crystalline and amorphous layers in an isotropic lamellar\nmaterial; the crystallinity degree; the fluctuation spacing due to\nentanglements; the neck draw ratio; the draw ratio at break; the elastic\ndeformation connected with gosh-trans transitions; etc. This model is based on\nthe assumption that there are exist two Lifshitz points in such polymers. The\nneck draw ratio characterizes an irreversible process during which the energy\ndissipation is observed. It is the main difference from magnetic systems, for\nexample. The results obtained are in a good agreement with experimental data\nincluding the results found for solution-crystallized polymers."
    },
    {
        "anchor": "Effect of dopant ordering on the stability of ferroelectric hafnia: Films of all-important compound hafnia (HfO2) can be prepared in an\northorhombic ferroelectric (FE) state that is ideal for applications, e.g. in\nmemories or negative-capacitance field-effect transistors. The origin of this\nFE state remains a mystery, though, as none of the proposed mechanisms for its\nstabilization -- from surface and size effects to formation kinetics -- is\nfully convincing. Interestingly, it is known that doping HfO2 with various\ncations favors the occurrence of the FE polymorph; however, existing\nfirst-principles works suggest that doping by itself is not sufficient to\nstabilize the polar phase over the usual non-polar monoclinic ground state.\nHere we use first-principles methods to reexamine this question. We consider\ntwo representative isovalent substitutional dopants, Si and Zr, and study their\npreferred arrangement within the HfO2 lattice. Our results reveal that small\natoms like Si can adopt very stable configurations (forming layers within\nspecific crystallographic planes) in the FE orthorhombic phase of HfO2, but\ncomparatively less so in the non-polar monoclinic one. Further, we find that,\nat low concentrations, such a dopant ordering yields a FE ground state, the\nusual paraelectric phase becoming a higher-energy metastable polymorph. We\ndiscuss the implications of our findings, which constitute a definite step\nforward towards understanding ferroelectricity in HfO2.",
        "positive": "Accelerating High-Strain Continuum-Scale Brittle Fracture Simulations\n  with Machine Learning: Failure in brittle materials under dynamic loading conditions is a result of\nthe propagation and coalescence of microcracks. Simulating this mechanism at\nthe continuum level is computationally expensive or, in some cases,\nintractable. The computational cost is due to the need for highly resolved\ncomputational meshes required to capture complex crack growth behavior, such as\nbranching, turning, etc. Typically, continuum-scale models that account for\nbrittle damage evolution homogenize the crack network in some way, which\nreduces the overall computational cost, but can also neglect key physics of the\nsubgrid crack growth behavior, sacrificing accuracy for efficiency. We have\ndeveloped an approach using machine learning that overcomes the current\ninability to represent micro-scale physics at the macro-scale. Our approach\nleverages damage and stress data from a high-fidelity model that explicitly\nresolves microcrack behavior to build an inexpensive machine learning emulator,\nwhich runs in seconds as opposed to the high-fidelity model, which takes hours.\nOnce trained, the machine learning emulator is used to predict the evolution of\ncrack length statistics. A continuum-scale constitutive model is then informed\nwith these crack statistics, speeding up the workflow by four orders of\nmagnitude. Both the machine learning model and the continuum-scale model are\nvalidated against a high-fidelity model and experimental data, respectively,\nshowing excellent agreement. There are two key findings. The first is that we\ncan reduce the dimensionality of the problem, establishing that the machine\nlearning emulator only needs the length of the longest crack and one of the\nmaximum stress components to capture the necessary physics. Another compelling\nfinding is that the emulator can be trained in one experimental setting and\ntransferred successfully to predict behavior in a different setting."
    },
    {
        "anchor": "Magnitude of pseudopotential localization errors in fixed node diffusion\n  quantum Monte Carlo: Growth in computational resources has lead to the application of real space\ndiffusion quantum Monte Carlo (DMC) to increasingly heavy elements. Although\ngenerally assumed to be small, we find that when using standard techniques the\npseudopotential localization error can be large, on the order of an electron\nvolt for an isolated cerium atom. We formally show that localization error can\nbe reduced to zero with improvements to the Jastrow factor alone and we define\na metric of Jastrow sensitivity that may be useful in the design of\npseudopotentials. We employ an extrapolation scheme to extract the bare fixed\nnode energy and estimate the localization error in both the locality\napproximation and the T-moves schemes for the Ce atom in charge states 3+ and\n4+. The locality approximation exhibits the lowest Jastrow sensitivity and\ngenerally smaller localization errors than T-moves, although the locality\napproximation energy approaches the localization free limit from above/below\nfor the 3+/4+ charge state. We find that energy minimized Jastrow factors\nincluding three-body electron-electron-ion terms are the most effective at\nreducing localization error for both the locality approximation and T-moves.\nLess complex or variance minimized Jastrows are generally less effective. Our\nresults suggest that further improvements to Jastrow factors and trial\nwavefunction forms will be necessary to reduce localization errors to chemical\naccuracy in calculations of heavy elements.",
        "positive": "The origin of increase of damping in transition metals with rare earth\n  impurities: The damping due to rare earth impurities in transition metals is discussed in\nthe low concentration limit. It is shown that the increase in damping is mainly\ndue to the coupling of the orbital moments of the rare earth impurities and the\nconduction $p$-electrons. It is shown that an itinerant picture for the host\ntransition ions is needed to reproduce the observed dependence of the damping\non the total angular moment of the rare earths."
    },
    {
        "anchor": "Modulation Doping of Silicon using Aluminium-induced Acceptor States in\n  Silicon Dioxide: All electronic, optoelectronic or photovoltaic applications of silicon depend\non controlling majority charge carriers via doping with impurity atoms.\nNanoscale silicon is omnipresent in fundamental research (quantum dots,\nnanowires) but also approached in future technology nodes of the\nmicroelectronics industry. In general, silicon nanovolumes, irrespective of\ntheir intended purpose, suffer from effects that impede conventional doping due\nto fundamental physical principles such as out-diffusion, statistics of small\nnumbers, quantum- or dielectric confinement. In analogy to the concept of\nmodulation doping, originally invented for III-V semiconductors, we demonstrate\na heterostructure modulation doping method for silicon. Our approach utilizes a\nspecific acceptor state of aluminium atoms in silicon dioxide to generate holes\nas majority carriers in adjacent silicon. By relocating the dopants from\nsilicon to silicon dioxide, Si nanoscale doping problems are circumvented. In\naddition, the concept of aluminium-induced acceptor states for passivating hole\nselective tunnelling contacts as required for high-efficiency photovoltaics is\npresented and corroborated by first carrier lifetime measurements.",
        "positive": "Unzipping graphene: Extendend defects by ion irradiation: Many of the proposed future applications of graphene require the controlled\nintroduction of defects into its perfect lattice. Energetic ions provide one\nway of achieving this challenging goal. Single heavy ions with kinetic energies\nin the 100 MeV range will produce nanometer-sized defects on dielectric but\ngenerally not on crystalline metal surfaces. In a metal the ion-induced\nelectronic excitations are efficiently dissipated by the conduction electrons\nbefore the transfer of energy to the lattice atoms sets in. Therefore, graphene\nis not expected to be irradiation sensitive beyond the creation of point\ndefects. Here we show that graphene on a dielectric substrate sustains major\nmodifications if irradiated under oblique angles. Due to a combination of\ndefect creation in the graphene layer and hillock creation in the substrate,\ngraphene is split and folded along the ion track yielding double layer\nnanoribbons. Our results indicate that the radiation hardness of graphene\ndevices is questionable but also open up a new way of introducing extended\nlow-dimensional defects in a controlled way."
    },
    {
        "anchor": "Magnetism and Interlayer Bonding in Pores of Bernal-Stacked Hexagonal\n  Boron Nitride: When single-layer h-BN is subjected to a high-energy electron beam,\ntriangular pores with nitrogen edges are formed. Because of the broken sp2\nbonds, these pores are known to possess magnetic states. We report on the\nmagnetism and electronic structure of triangular pores as a function of their\nsize. Moreover, in the Bernal-stacked h-BN (AB-h-BN), multilayer pores with\nparallel edges can be created, which is not possible in the commonly fabricated\nmultilayer AA'-h-BN. Given that these pores can be manufactured in a\nwell-controlled fashion using an electron beam, it is important to understand\nthe interactions of pores in neighboring layers. We find that in certain\nconfigurations, the edges of the neighboring pores remain open and retain their\nmagnetism, and in others, they form interlayer bonds. We present a\ncomprehensive report on these configurations for small nanopores. We find that\nat low temperatures, these pores have near degenerate magnetic configurations,\nand may be utilized in magnetoresistance and spintronics applications. In the\nprocess of forming larger multilayer nanopores, interlayer bonds can form,\nreducing the magnetization. Yet, unbonded parallel multilayer edges remain\navailable at all sizes. Understanding these pores is also helpful in a\nmultitude of applications such as DNA sequencing and quantum emission.",
        "positive": "New stable crystal structures of C and GeC2 predicted from\n  first-principles calculations: Two novel three-dimensional (3D) crystal structures of carbon (C) and\ngermanium carbide (GeC2) were predicted using first-principles\ndensity-functional theory (DFT) calculations. These newly discovered 3D carbon\nallotrope and GeC2 are in the space group of Fmmm (space group number 69).\nTheir crystal structures have unique tetragonal/hexagonal rings formed by\neither C or Ge/C atoms. Both structures were proven to be thermodynamically\nstable through the phonon spectrum calculations. The C allotrope is a\nsemiconductor with a wide band gap of 3.65 eV predicted by the hybrid density\nfunctional HSE06 method, while GeC2 is metallic. The new C allotrope has a low\nmass density of 2.84 g/cm3. More importantly, it is proven to be energetically\nstable with cohesive energy less than -7.5 eV/atom which is lower than many\nother carbon allotropes implying the possibility to be fabricated in lab. Such\na carbon crystal structure with a low mass density and wide band gap once\nsynthesized would have wide applications in gas adsorption sensors and\nphoto-electronic devices."
    },
    {
        "anchor": "Energy Dependence of Cu L2,3 Satellites using Synchrotron Excited X-ray\n  Emission Spectroscopy: The L2,3 X-ray emission of Cu metal has been measured using monochromatic\nsynchrotron radiation. The self-absorption effect in the spectra is shown to be\nvery small in our experimental geometry. From the quantitative analysis of\nspectra recorded at different excitation energies, the L3/L2 emission intensity\nratio and the partial Auger-width are extracted. High-energy satellite features\non the L3 emission line are separated by a subtraction procedure. The satellite\nintensity is found to be slowly increasing for excitation energies between the\nL3, L2 and L1 core-level thresholds due to shake-up and shake-off transitions.\nAs the excitation energy passes the L2 threshold, a step of rapidly increasing\nsatellite intensity of the L3 emission is found due to additional Coster-Kronig\nprocesses.",
        "positive": "Optical Identification of a DNA-Wrapped Carbon Nanotube: Signs of\n  Helically Broken Symmetry: High intrinsic mobility and small, biologically-compatible size make\nsingle-walled carbon nanotubes (SWNTs) in demand for the next generation of\nelectronic devices. Further, the wide range of available bandgaps due to\nchanges in diameter and symmetry give SWNTs greater versatility than\ntraditional semiconductors. Single-stranded DNA has been employed to make these\ndesirable properties accessible for large scale fabrication of devices. Because\nsingle-stranded DNA can helically wrap a SWNT, forming a stable hybrid\nstructure, DNA/polymer wrapping has been used to disperse bundles of\nintrinsically hydrophobic SWNTs into individual tubes in aqueous solution. The\nability to isolate individual tubes, make them soluble, and separate them\naccording to symmetry would enable fabrication of SWNT optoelectronic devices\nthat benefit from the unique electronic properties of specific nanotube\nstructures. Envisioning optoelectronic applications of nanotubes, we\ninvestigate whether the optical properties of DNA-wrapped SWNT materials are\ndifferent than those of pristine SWNTs. Our previous work found that\nbandstructures of DNA-SWNTs were indeed affected by the charged wrap. That is,\nthe direct optical bandgap, $E_{11}$, decreases, but changes are fairly small.\nThis is consistent with the available experimental data in standard\nexperimental geometry in which incident light is polarized along the SWNT axis.\nHere we consider optical absorption of light with perpendicular (or circular)\npolarization with respect to the tube axis, which has been measured\nexperimentally for SWNTs dispersed using a surfactant. In this geometry we find\nqualitative changes in the absorption spectra of SWNTs upon hybridization with\nDNA, including strong optical circular dichroism in non-chiral SWNTs."
    },
    {
        "anchor": "On the Newtonian origin of the spin motive force in ferromagnetic atomic\n  wires: We demonstrate numerically the existence of a spin-motive force acting on\nspin-carriers when moving in a time and space dependent internal field. This is\nthe case of electrons in a one-dimensional wires with a precessing domain wall.\nThe effect can be explained solely by considering adiabatic dynamics and it is\nshown to exist for both classical and quantum systems.",
        "positive": "Anisotropic defect-induced ferromagnetism and transport in Gd-doped GaN\n  two-dimensional electron gasses: Here we report on the effect of rare earth Gd-doping on the magnetic\nproperties and magnetotransport of GaN two-dimensional electron gasses (2DEGs).\nSamples are grown by plasma-assisted molecular beam epitaxy and consist of\nAlN/GaN heterostructures where Gd is delta-doped within a polarization-induced\n2DEG. Ferromagnetism is observed in these Gd-doped 2DEGs with a Curie\ntemperature above room temperature and an anisotropic spontaneous magnetization\npreferring an out-of-plane (c-axis) orientation. At magnetic fields up to 50\nkOe, the magnetization remains smaller for in-plane configuration than for\nout-of-plane, which is indicative of exchange coupled spins locked along the\npolar c-axis. The sample with the lowest Gd concentration (2.3 $\\times$\n$10^{14}$ cm$^{-2}$) exhibits a saturation magnetization of 41.1\n$\\mu_B/Gd^{3+}$ at 5 K revealing that the Gd ion spins (7 ${\\mu}_B$) alone do\nnot account for the magnetization. Surprisingly, control samples grown without\nany Gd display inconsistent magnetic properties; in some control samples weak\nferromagnetism is observed and in others paramagnetism. The ferromagnetic 2DEGs\ndo not exhibit the anomalous Hall effect; the Hall resistance varies\nnon-linearly with the magnetic field, but does not track the magnetization\nindicating the lack of coupling between the ferromagnetic phase and the\nconduction band electrons within the 2DEG."
    },
    {
        "anchor": "The Onset of Phase Separation in the Double Perovskite Oxide\n  La$_2$MnNiO$_6$: Identification of kinetic and thermodynamic factors that control crystal\nnucleation and growth represents a central challenge in materials synthesis.\nHere we report that apparently defect-free growth of La$_2$MnNiO$_6$ (LMNO)\nthin films supported on SrTiO$_3$ (STO) proceeds up to $1-5$ nm, after which it\nis disrupted by precipitation of NiO phases. Local geometric phase analysis and\nensemble-averaged X-ray reciprocal space mapping show no change in the film\nstrain away from the interface, indicating that mechanisms other than strain\nrelaxation induce the formation of the NiO phases. $Ab \\, initio$ simulations\nsuggest that oxygen vacancies become more likely with increasing thickness, due\nto the electrostatic potential build-up associated with the polarity mismatch\nat the film-substrate interface, this, in turn, promotes the formation of\nNi-rich regions. These results suggest that the precipitate-free region could\nbe extended further by increasing the oxygen chemical potential through the use\nof an elevated oxygen pressure or by incorporating electron redistributing\ndopants to suppress the built-in potential.",
        "positive": "Atomic-scale insights into electro-steric substitutional chemistry of\n  cerium oxide: Cerium oxide (ceria, CeO2) is one of the most promising mixed ionic and\nelectronic conducting materials. Previous atomistic analysis has covered widely\nthe effects of substitution on oxygen vacancy migration. However, an in-depth\nanalysis of the role of cation substitution beyond trivalent cations has rarely\nbeen explored. Here, we investigate soluble monovalent, divalent, trivalent and\ntetravalent cation substituents. By combining classical simulations and quantum\nmechanical calculations, we provide an insight into defect association energies\nbetween substituent cations and oxygen vacancies as well as their effects on\nthe diffusion mechanisms. Our simulations indicate that oxygen ionic\ndiffusivity of subvalent cation-substituted systems follows the order Gd>Ca>Na.\nWith the same charge, a larger size mismatch with Ce cation yields a lower\noxygen ionic diffusivity, i.e., Na>K, Ca>Ni, Gd>Al. Based on these trends, we\nidentify species that could tune the oxygen ionic diffusivity: we estimate that\nthe optimum oxygen vacancy concentration for achieving fast oxygen ionic\ntransport is 2.5% for GdxCe1-xO2-x/2, CaxCe1-xO2-x and NaxCe1-xO2-3x/2 at 800\nK. Remarkably, such a concentration is not constant and shifts gradually to\nhigher values as the temperature is increased. We find that co-substitutions\ncan enhance the impact of the single substitutions beyond that expected by\ntheir simple addition. Furthermore, we identify preferential oxygen ion\nmigration pathways, which illustrate the electro-steric effects of substituent\ncations in determining the energy barrier of oxygen ion migration. Such\nfundamental insights into the factors that govern the oxygen diffusion\ncoefficient and migration energy would enable design criteria to be defined for\ntuning the ionic properties of the material, e.g., by co-doping."
    },
    {
        "anchor": "A comparative study of SiC epitaxial growth in vertical hotwall CVD\n  reactor using silane and dichlorosilane precursor gases: SiC epitaxial films grown in an inverted chimney CVD reactor are analyzed and\ncompared for growth rates, doping concentration and surface morphology using\nsilane-propane-hydrogen and dichlorosilane (DCS)-propane-hydrogen chemistry\nsystems. A general 1-D analytical model is presented to estimate the\ndiffusivity of precursor gases, boundary layer thickness and growth rates for\nboth gas systems. Decomposition of precursor gases into Si growth species is\ninvestigated by a commercial simulation tool, Virtual Reactor (VR). DCS\nsuppresses the formation of elemental Si at lower pressures, reduces precursor\nlosses, and leads to increased growth rate. However, at higher pressures, even\nDCS decomposes into elemental Si, which contributes to high Si depletion,\nlimiting the maximum achievable growth rate. Reduction of Si loss using DCS is\nverified by mass measurements of parasitic depositions in the injector tube.\nThe doping concentration of the epitaxial film is governed by the effective\nC/Si ratio at the growth surface rather than the inlet C/Si ratio, which is\nexamined at various growth pressures. In addition to the widely known\nSi-depletion, C-depletion is also shown to exist and it plays a critical role\nin determining the doping concentration at various growth conditions. Increased\nroughness for the DCS growth at higher pressures is addressed and attributed to\nexcessive HCl etching at higher pressures.",
        "positive": "Metal Oxide-Vertical Graphene Nanosheets for 2.6 V Aqueous\n  Electrochemical Hybrid Capacitor: Aqueous asymmetric electrochemical capacitor, with their high power density\nand superior cycle stability in comparison to conventional batteries, are\npresently considered as the most promising contender for energy storage.\nHowever, fabricating an electrode material and choosing a suitable aqueous\nelectrolyte are vital in developing an electrochemical capacitor device with\nhigh charge storage capacity. Herein, we report a feasible method to synthesize\nMnO2/Vertical graphene nanosheets (VGN) and Fe2O3/VGN as positive and negative\nelectrodes, respectively. The surface of VGN skeleton is independently\ndecorated with MnO2 having sponge gourd-like morphology and Fe2O3 having\nnanorice like morphology. A schematic representation of the growth mechanism\nfor metal oxide on VGN network is established. Both the electrode have shown\naround 250 times higher charge-storage capacity than the bare VGN (0.47 mF/cm2)\nwith the specific capacitance of 118 (MnO2/VGN) and 151 mF/cm2 (Fe2O3/VGN). In\naddition to the double layer capacitance contribution, the porous\ninterconnected vertical graphene architecture serves as a mechanical backbone\nfor the metal oxide materials and provides multiple conducting channels for the\nelectron transport. The fabricated asymmetric device exhibited a specific\ncapacitance of 76 mF/cm2 and energy density of 71 microWh/cm2 with an excellent\nelectrochemical stability up to 12000 cycles, over a potential window of 2.6 V.\nThe commendable performance of asymmetric electrochemical capacitor device\nauthenticated its potential utilization for next-generation portable energy\nstorage device."
    },
    {
        "anchor": "Effect of structural disorder on the Kitaev magnet\n  Ag$_{3}$LiIr$_{2}$O$_{6}$: Searching for an ideal Kitaev spin liquid candidate with anyonic excitations\nand long-range entanglement has motivated the synthesis of a new family of\nintercalated Kitaev magnets such as H$_{3}$LiIr$_{2}$O$_{6}$,\nCu$_{2}$IrO$_{3}$, and Ag$_{3}$LiIr$_{2}$O$_{6}$. The absence of a\nsusceptibility peak and a two-step release of the magnetic entropy in these\nmaterials has been proposed as evidence of proximity to the Kitaev spin liquid.\nHere we present a comparative study of the magnetic susceptibility, heat\ncapacity, and muon spin relaxation ($\\mu$SR) between two samples of\nAg$_{3}$LiIr$_{2}$O$_{6}$ in the clean and disordered limits. In the disordered\nlimit, the absence of a peak in either susceptibility or heat capacity and a\nweakly depolarizing $\\mu$SR signal may suggest a proximate spin liquid ground\nstate. In the clean limit, however, we resolve a peak in both susceptibility\nand heat capacity data, and observe clear oscillations in $\\mu$SR that confirm\nlong-range antiferromagnetic ordering. The $\\mu$SR oscillations fit to a Bessel\nfunction, characteristic of an incommensurate order, as reported in the parent\ncompound $\\alpha$-Li$_{2}$IrO$_{3}$. Our results clarify the role of structural\ndisorder in the intercalated Kitaev magnets.",
        "positive": "Probing Topological Floquet States in WSe$_2$ using Circular Dichroism\n  in Time- and Angle-Resolved Photoemission Spectroscopy: Observing signatures of light-induced Floquet topological states in materials\nhas been shown to be very challenging. Angle-resolved photoemission\nspectroscopy (ARPES) is well suited for the investigation of Floquet physics,\nas it allows to directly probe the dressed electronic states of driven solids.\nDepending on the system, scattering and decoherence can play an important role,\nhampering the emergence of Floquet states. Another challenge is to disentangle\nFloquet side bands from laser-assisted photoemission (LAPE), since both lead to\nsimilar signatures in ARPES spectra. Here, we investigate the emergence of\nFloquet state in the transition metal dichalcogenide $2H$-WSe$_2$, one of the\nmost promising systems for observing Floquet physics. We discuss how the\nFloquet topological state manifests in characteristic features in the circular\ndichroism in photoelectron angular distributions (CDAD) that is determined by\nthe transient band structure modifications and the associated texture of the\norbital angular momentum. Combining highly accurate modeling of the\nphotoemission matrix elements with an \\emph{ab initio} description of the\nlight-matter interaction, we investigate regimes which can be realized in\ncurrent state-of-the-art experimental setups. The predicted features are robust\nagainst scattering effects and are expected to be observed in forthcoming\nexperiments."
    },
    {
        "anchor": "Accelerating small-angle scattering experiments with simulation-based\n  machine learning: Making material experiments more efficient is a high priority for materials\nscientists who seek to discover new materials with desirable properties. In\nthis paper, we investigate how to optimize the laborious sequential\nmeasurements of materials properties with data-driven methods, taking the\nsmall-angle neutron scattering (SANS) experiment as a test case. We propose two\nmethods for optimizing sequential data sampling. These methods iteratively\nsuggest the best target for the next measurement by performing a statistical\nanalysis of the already acquired data, so that maximal information is gained at\neach step of an experiment. We conducted numerical simulations of SANS\nexperiments for virtual materials and confirmed that the proposed methods\nsignificantly outperform baselines.",
        "positive": "A concept for Lithography-free patterning of silicon heterojunction\n  back-contacted solar cells by laser processing: Silicon heterojunction (SHJ) solar cells with an interdigitated back-contact\n(IBC) exhibit high conversion efficiencies of up to 25.6%. However, due to the\nsophisticated back-side pattern of the doped layers and electrode structure\nmany processing and patterning steps are required. A simplification of the\npatterning steps could ideally increase the yield and/or lower the production\ncosts. We propose a patterning approach for IBC SHJ solar cells free of any\nphoto-lithography with the help of laser-induced forward transfer (LIFT) of the\nindividual layer stacks to create the required back-contact pattern. The\nconcept has the potential to lower the number of processing steps significantly\nwhile at the same time giving a large degree of freedom in the processing\nconditions optimization of emitter and BSF since deposition of the\nintrinsic/doped layers and processing of the wafer are all independent from\neach other."
    },
    {
        "anchor": "Electronic Stopping of Slow Protons in Transition and Rare Earth Metals:\n  Breakdown of the Free Electron Gas Concept: The electronic stopping cross sections (SCS) of Ta and Gd for slow protons\nhave been investigated experimentally. The data are compared to the results for\nPt and Au to learn how electronic stopping in transition and rare earth metals\ncorrelates with features of the electronic band structures. The extraordinarily\nhigh SCS observed for protons in Ta and Gd cannot be understood in terms of a\nfree electron gas model, but are related to the high densities of both occupied\nand unoccupied electronic states in these metals.",
        "positive": "Accurate FTIR determination of boron concentration in CVD homoepitaxial\n  diamond layers: The intensive development of technology for fabrication semiconducting CVD\ndiamond layers poses an important task of developing a precise and\nnon-destructive method for estimation the boron content in thin epitaxial\nlayers. For bulk and uniformly doped diamond samples, the infrared optical\nspectroscopy successfully performs such a role. Here we propose a correct\nmethod to determine the boron concentration in CVD homoepitaxial diamond layers\nfrom FTIR spectra. The method is the natural advancement of the existing\ntechnique for bulk samples. The feature of the novel technique is the accurate\naccounting of passing radiation through a multilayered structure with different\nthicknesses of absorbing media for special absorbing mechanisms. For this\nsituation, an expression for the effective optical density is obtained. We have\ndemonstrated the benefit of the method for a set of samples with CVD\nhomoepitaxial layers grown on various HPHT substrates with and without nitrogen\nimpurity. The measured FTIR spectra were subdivided into relevant sections\nresponsible for the specific absorption mechanisms, and the correct amplitudes\nof the boron absorption peaks were derived. The data obtained from FTIR spectra\nis thoroughly compared to the charge carrier concentration derived from\nelectrical capacitance-voltage measurements."
    },
    {
        "anchor": "Tail-states induced semiconductor-toconductor like transition under\n  sub-bandgap light excitation in the zinc-tin-oxide photothinfilm transistors: We report on a giant persistent photoconductivity (PPC) induced\nsemiconductor-to-conductor like transition in zinc-tin-oxide (ZTO)\nphoto-thinfilm transistors (TFT). The active ZTO channel layer was prepared by\nremote-plasma reactive sputtering and possesses an amorphous structure. Under\nsubbandgap excitation of ZTO with UV light, the photocurrent reaches as high as\n~10 -4 A (a photo-to-dark current ratio of ~10 7) and remains close to this\nhigh value after switching off the light. During this time, the ZTO TFT\nexhibits gigantic PPC with long-lasting recovery time, which leads the ZTO\ncompound to undergo a semiconductor-to-conductor like transition. In the\npresent case, the conductivity changes over six orders of magnitude, from ~10-7\nto 0.92 {\\Omega} -1cm-1. After UV exposure, the ZTO compound can potentially\nremain in the conducting state for up to a month. The underlying physics of the\nobserved PPC effect is investigated by studying defects (deep-states and\ntail-states) by employing a discharge current analysis (DCA) technique.\nFindings from the DCA study reveal direct evidence for the involvement of\nsub-gap tail-states of the ZTO in the giant PPC, while deep-states contribute\nto mild PPC.",
        "positive": "Double polarization hysteresis loop induced by the domain pinning by\n  defect dipoles in HoMnO3 epitaxial thin films: We report on antiferroelectriclike double polarization hysteresis loops in\nmultiferroic HoMnO3 thin films below the ferroelectric Curie temperature. This\nintriguing phenomenon is attributed to the domain pinning by defect dipoles\nwhich were introduced unintentionally during film growth process. Electron\nparamagnetic resonance suggests the existence of Fe1+ defects in thin films and\nfirst principles calculations reveal that the defect dipoles would be composed\nof oxygen vacancy and Fe1+ defect. We discuss migration of charged point\ndefects during film growth process and formation of defect dipoles along\nferroelectric polarization direction, based on the site preference of point\ndefects. Due to a high-temperature low-symmetry structure of HoMnO3, aging is\nnot required to form the defect dipoles in contrast to other ferroelectrics\n(e.g., BaTiO3)."
    },
    {
        "anchor": "Symmetry of ferroelectric switching and domain walls in hafnium dioxide: Hafnium dioxide (HfO2) is a promising ferroelectric (FE) material for\nachieving high-density nonvolatile memory and neuromorphic computing, due to\nits compatibility with the mainstream integrated circuit technology and the\nsurprisingly enhanced ferroelectricity by reduced thickness. The FE switching\ndynamics is essential to the device performance, but the complexity of HfO2\natomic structure causes unknown of various FE switching paths and domain wall\nconfigurations. Here, we demonstrate that its low-barrier paths and domain\nwalls can be comprehensively found and understood from a perspective of\ntopological symmetry. By discussing pseudo-chirality and equivalent\ntransformation relations in crystal with first principles and lattice modes, we\nclassify and analyze 4 low-barrier FE switching paths and 93 irreducible\ntopology domain wall configurations in HfO2. Anisotropic switching mechanism is\nfound based on the mobility investigation for 12 types of 180{\\deg} side domain\nwalls. This methodology is expected to be generally applicable to displacive\nferroelectrics with low unit cell point group symmetries, and lay a foundation\nfor mechanism study of the switching dynamics.",
        "positive": "Theoretical study of the thermal behavior of free and alumina-supported\n  Fe-C nanoparticles: The thermal behavior of free and alumina-supported iron-carbon nanoparticles\nis investigated via molecular dynamics simulations, in which the effect of the\nsubstrate is treated with a simple Morse potential fitted to ab initio data. We\nobserve that the presence of the substrate raises the melting temperature of\nmedium and large $Fe_{1-x}C_x$ nanoparticles ($x$ = 0-0.16, $N$ = 80-1000, non-\nmagic numbers) by 40-60 K; it also plays an important role in defining the\nground state of smaller Fe nanoparticles ($N$ = 50-80). The main focus of our\nstudy is the investigation of Fe-C phase diagrams as a function of the\nnanoparticle size. We find that as the cluster size decreases in the\n1.1-1.6-nm-diameter range the eutectic point shifts significantly not only\ntoward lower temperatures, as expected from the Gibbs-Thomson law, but also\ntoward lower concentrations of C. The strong dependence of the maximum C\nsolubility on the Fe-C cluster size may have important implications for the\ncatalytic growth of carbon nanotubes by chemical vapor deposition."
    },
    {
        "anchor": "GPT-4 as an interface between researchers and computational software:\n  improving usability and reproducibility: Large language models (LLMs) are playing an increasingly important role in\nscience and engineering. For example, their ability to parse and understand\nhuman and computer languages makes them powerful interpreters and their use in\napplications like code generation are well-documented. We explore the ability\nof the GPT-4 LLM to ameliorate two major challenges in computational materials\nscience: i) the high barriers for adoption of scientific software associated\nwith the use of custom input languages, and ii) the poor reproducibility of\npublished results due to insufficient details in the description of simulation\nmethods. We focus on a widely used software for molecular dynamics simulations,\nthe Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), and\nquantify the usefulness of input files generated by GPT-4 from task\ndescriptions in English and its ability to generate detailed descriptions of\ncomputational tasks from input files. We find that GPT-4 can generate correct\nand ready-to-use input files for relatively simple tasks and useful starting\npoints for more complex, multi-step simulations. In addition, GPT-4's\ndescription of computational tasks from input files can be tuned from a\ndetailed set of step-by-step instructions to a summary description appropriate\nfor publications. Our results show that GPT-4 can reduce the number of routine\ntasks performed by researchers, accelerate the training of new users, and\nenhance reproducibility.",
        "positive": "Surface phonon propagation in topological insulators: The effect of helical Dirac states on surface phonons in a topological\ninsulators is investigated. Their coupling is derived in the continuum limit by\nassuming displacement dependent Dirac cones. The resulting renormalisation of\nsound velocity and attenuation and its dependence on chemical potential and\nwave vector is calculated. At finite wave vectors a Kohn anomaly in the\nrenormalized phonon frequency is caused by intraband-transitions. It appears at\nwave vectors q<2k_F due to a lack of backscattering for helical Dirac\nelectrons. The wave vector and chemical potential dependence of this anomaly is\ncalculated."
    },
    {
        "anchor": "Modelling of microstructures during in-situ alloying in additive\n  manufacturing for efficient material qualification processes: In this work, a numerical simulation framework is presented based on the\nPhase Field Method that is able to capture the evolution of heterogeneous\nmetallic microstructures during solidification. The involved physics can prove\nespecially useful when studying not only systems undergoing thermal gradients,\nsuch as in homogeneous systems, but also in conditions that exhibit stark\nspatial gradients, i.e. when these inhomogeneities are present even on a\nmesoscopic scale. To illustrate the capabilities of the model, in-situ alloying\nof a High Entropy Alloy during Laser Powder Bed Fusion is investigated as an\nexemplary use case. The resulting digital twin is expected to shorten\ndevelopment times of new materials as well as cut down on experimental resource\nneeds considerably, therefore contributing to efficient material qualification\nprocesses.",
        "positive": "Multi-Hill Strategy in Metadynamics for Interstitial Diffusion in\n  Crystals: We propose an efficient and general strategy of metadynamics (MetaD) for\ninvestigating interstitial diffusion in a crystal by exploiting\ncrystallographic symmetry. Assuming complete ignorance of the diffusion\nphenomenon of interest, the three-dimensional coordinates of the interstitial\natom with the periodic boundaries are chosen as the collective variables (CVs).\nMultiple potential hills are simultaneously deposited at all\ncrystallographically-equivalent positions on the free energy surface (FES)\ndefined in the CV space. As a result, the proposed multi-hill strategy highly\naccelerates atomic jumps in comparison with the single-hill strategy in the\nconventional MetaD. The key features are that the FES estimated from the final\nbias potential is exactly satisfied with the symmetry of the host crystal and\nthat all elementary processes of interstitial diffusion are obtained by the\nsingle MetaD simulation without any prior knowledge on the diffusion mechanism.\nThe high efficiency and efficacy of the multi-hill strategy are demonstrated,\ntaking the proton diffusion in barium zirconate with the cubic perovskite\nstructure as a model case."
    },
    {
        "anchor": "Green tea induced gold nanostar synthesis mediated by Ag(I) ions: We report a synthesis of tea components conjugated gold nanostars (AuNSs)\nwith strong near infrared absorption by reducing an aqueous solution of\nchloroauric acid trihydrate via green tea in association with Ag(I) ions. Green\ntea acts as a reducing agent by providing electrons for the gold (III)\nreduction as well as a stabilizing agent by conjugating some of its components\non the surfaces of AuNSs. Moreover, the Ag(I) ions play an important role in\nmediating the branched growth of the resultant AuNSs by inducing anisotropic\ngrowth on the surfaces of initially formed spherical gold nanoparticles.",
        "positive": "Moir\u00e9 Synergy: An Emerging Game Changer by Moir\u00e9 of Moir\u00e9: Moir\\'e superlattices of tunable wavelengths and the further developed\nmoir\\'e of moir\\'e systems, by artificially assembling two-dimensional (2D) van\nder Waals (vdW) materials as designed, have brought up a versatile toolbox to\nexplore fascinating condensed mater physics and their stimulating\nphysicochemical functionalities. In this Perspective, we briefly review the\nrecent progress in the emerging field of moir\\'e synergy, highlighting the\nsynergetic effects arising in distinct dual moir\\'e heterostructures of\ngraphene and transition metal dichalcogenides (TMDCs). A spectrum of moir\\'e of\nmoir\\'e configurations, the advanced characterization and the exploitation\nefforts on the moir\\'e-moir\\'e interactions will be discussed. Finally, we look\nout for urgent challenges to be conquered in the community and some potential\nresearch directions in the near future."
    },
    {
        "anchor": "Mesoscale Defect Motion in Binary Systems: Effects of Compositional\n  Strain and Cottrell Atmospheres: The velocity of dislocations is derived analytically to incorporate and\npredict the intriguing effects induced by the preferential solute segregation\nand Cottrell atmospheres in both two-dimensional and three-dimensional binary\nsystems of various crystalline symmetries. The corresponding mesoscopic\ndescription of defect dynamics is constructed through the amplitude formulation\nof the phase-field crystal model which has been shown to accurately capture\nelasticity and plasticity in a wide variety of systems. Modifications of the\nPeach-Koehler force as a result of solute concentration variations and\ncompositional stresses are presented, leading to interesting new predictions of\ndefect motion due to effects of Cottrell atmospheres. These include the\ndeflection of dislocation glide paths, the variation of climb speed and\ndirection, and the change or prevention of defect annihilation, all of which\nplay an important role in determining the fundamental behaviors of complex\ndefect network and dynamics. The analytic results are verified by numerical\nsimulations.",
        "positive": "Epitaxial growth and orientation-dependent anomalous Hall effect of\n  noncollinear antiferromagnetic Mn$_3$Ni$_{0.35}$Cu$_{0.65}$N films: We report the growth of noncollinear antiferromagnetic (AFM)\nMn$_3$Ni$_{0.35}$Cu$_{0.65}$N films and the orientation-dependent anomalous\nHall effect (AHE) of (001) and (111) films due to nonzero Berry curvature. We\nfound that post-annealing at 500$^\\circ$C can significantly improve the AHE\nsignals, though using the appropriate post-annealing conditions is important.\nThe AHE and magnetization loops show sharp flipping at the coercive field in\n(111) films, while (001) films are hard to saturate by a magnetic field. The\nanomalous Hall conductivity of (111) films is an order of magnitude larger than\nthat of (001) films. The present results provide not only a better\nunderstanding of the AHE in Mn$_3X$N systems but also further opportunities to\nstudy the unique phenomena related to noncollinear AFM."
    },
    {
        "anchor": "Probing anisotropy in epitaxial Fe/Pt bilayers by spin-orbit torque\n  ferromagnetic resonance: We report the generation and detection of spin-orbit torque ferromagnetic\nresonance (STFMR) in micropatterned epitaxial Fe/Pt bilayers grown by molecular\nbeam epitaxy. The magnetic field dependent measurements at an in-plane magnetic\nfield angle of 45 degrees with respect to the microwave-current direction\nreveal the presence of two distinct voltage peaks indicative of a strong\nmagnetic anisotropy. We show that STFMR can be employed to probe the underlying\nmagnetic properties including the anisotropies in the Fe layer. We compare our\nSTFMR results with broadband ferromagnetic resonance spectroscopy of the\nunpatterned bilayer thin films. The experimental STFMR measurements are\ninterpreted using an analytical formalism and further confirmed using\nmicromagnetic modeling, which shed light on the field-dependent magnetization\nalignment in the microstructures responsible for the STFMR rectification. Our\nresults demonstrate a simple and efficient method for determining magnetic\nanisotropies in microstructures by means of rf spectroscopy.",
        "positive": "The ferroelectric polarization of Y2CoMnO6 aligns along the b-axis: the\n  first-principles calculations: Double-perovskite A2BB'O6 oxides with magnetic B and B' ions and E*-type\nantiferromagnetic order (E*-AFM, i.e. the ++-- structure) are believed to\nexhibit promising multiferroic properties, and Y2CoMnO6 (YCMO) is one candidate\nin this category. However, the microscopic origins for magnetically induced\nferroelectricity in YCMO remain unclear. In this work, we perform detailed\nsymmetry analysis on the exchange striction effect and lattice distortion, plus\nthe first-principles calculations on YCMO. The E*-AFM state as the ground state\nwith other competing states such as ferromagnetic and A-antiferromagnetic\norders is confirmed. It is revealed that the ferroelectricity is generated by\nthe exchange striction associated with the E*-AFM order and chemically rdered\nMn/Co occupation. Both the lattice symmetry consideration and first-principles\ncalculations predict that the electric polarization aligns along the b-axis.\nThe calculated polarization reaches up to 0.4682 uC/cm2, mainly from the ionic\ndisplacement contribution. The present work presents a comprehensive\nunderstanding of the multiferroic mechanisms in YCMO and is of general\nsignificance for predicting emergent multiferroicity in other double-perovskite\nmagnetic oxides."
    },
    {
        "anchor": "Capillary origami of micro-machined micro-objects: Bi-layer conductive\n  hinges: Recently, we demonstrated controllable 3D self-folding by means of capillary\nforces of silicon-nitride micro-objects made of rigid plates connected to each\nother by flexible hinges [1]. In this paper, we introduce platinum electrodes\nrunning from the substrate to the plates over these bendable hinges. The\nfabrication yield is as high as (77 +/- 2) % for hinges with a length less than\n75 {\\mu}m. The yield reduces to (18 +/- 2) % when the length increases above\n100 {\\mu}m. Most of the failures in conductivity are due to degradation of the\nplatinum/chromium layer stack during the final plasma cleaning step. The\nbi-layer hinges survive the capillary folding process, even for extremely small\nbending radii of 5 {\\mu}m, nor does the bending have any impact on the\nconductivity. Stress in the different layers deforms the hinges, which does not\naffect the conductivity. Once assembled, the conductive hinges can withstand a\ncurrent density of (1.6 +/- 0.4) $10^6$ A/cm$^2$ . This introduction of\nconductive electrodes to elastocapillary self-folded silicon-based\nmicro-objects extends the range of their possible applications by allowing an\nelectronic functionality of the folded parts.",
        "positive": "Impact-driven effects in thin-film growth: steering and transient\n  mobility at the Ag(110) surface: Low-energy atomic impacts on the Ag(110) surface are investigated by\nmolecular dynamics simulations based on reliable many-body semiempirical\npotentials. Trajectory deflections (steering) caused by the atom-surface\ninteraction are observed, together with impact-following, transient-mobility\neffects. Such processes are quantitatively analysed and their dependence on the\ninitial kinetic energy and on the impinging direction is discussed. A clear\ninfluence of the surface anisotropy on both steering and transient mobility\neffects is revealed by our simulations for the simple isolated-atom case and in\nthe submonolayer-growth regime. For the latter case, we illustrate how steering\nand transient mobility affect the film morphology at the nanoscale."
    },
    {
        "anchor": "Mechanisms governing phonon scattering by topological defects in\n  graphene nanoribbons: Understanding phonon scattering by topological defects in graphene is of\nparticular interest for thermal management in graphene-based devices. We\npresent a study that quantifies the roles of the different mechanisms governing\ndefect phonon scattering by comparing the effects of ten different defect\nstructures using molecular dynamics. Our results show that phonon scattering is\nmainly influenced by mass density difference, with general trends governed by\nthe defect formation energy and typical softening behaviors in the phonon\ndensity of state. The phonon scattering cross-section is found to be far larger\nthan that geometrically occupied by the defects. We also show that the lattice\nthermal conductivity can be reduced by a factor of up to ~30 in the presence of\nthe grain boundaries formed by these defects.",
        "positive": "Ultrafast transport and energy relaxation of hot electrons in\n  Au/Fe/MgO(001) heterostructures analyzed by linear time-resolved\n  photoelectron spectroscopy: In condensed matter, scattering processes determine the transport of charge\ncarriers. In case of heterostructures, interfaces determine many dynamic\nproperties like charge transfer and transport and spin current dynamics. Here\nwe discuss optically excited electron dynamics and their propagation across a\nlattice-matched, metal-metal interface of single crystal quality. Using\nfemtosecond time-resolved linear photoelectron spectroscopy upon optically\npumping different constituents of the heterostructure we establish a technique\nwhich probes the electron propagation and its energy relaxation simultaneously.\nIn our approach a near-infrared pump pulse excites electrons directly either in\nthe Au layer or in the Fe layer of epitaxial Au/Fe/MgO(001) heterostructures\nwhile the transient photoemission spectrum is measured by an ultraviolet probe\npulse on the Au surface. Upon femtosecond laser excitation, we analyze the\nrelative changes in the electron distribution close to the Fermi energy and\nassign characteristic features of the time-dependent electron distribution to\ntransport of hot and non-thermalized electrons from the Fe layer to the Au\nsurface and vice versa. From the measured transient electron distribution we\ndetermine the excess energy which we compare with a calculation based on the\ntwo-temperature model and takes diffusive electron transport into account. On\nthis basis we identify a transition from a super-diffusive to a diffusive\ntransport regime to occur for a Au layer thickness of 20-30~nm."
    },
    {
        "anchor": "Amorphous Ni50Ti50 Alloy with Nanoporous Structure Generated by\n  Ultrafast Isobaric Cooling: Amorphous metallic foams are prospective materials due to unique combination\nof their mechanical and energy-absorption properties. In the present work,\natomistic dynamics simulations are performed under isobaric conditions with the\npressure $p = 1.0$ atm in order to study how cooling with extremely high rates\n($5\\times10^{13}$--$5\\times10^{14}$ K/s) affects the formation of pores in\namorphous titanium nickelide. For equilibrium liquid phase, vaporization\ntemperature $T_{b}$ and the equation of states in the form of $\\rho(T)$ are\ndetermined. It is found that the porosity of this amorphous solid does not\ndepend on cooling at such high rates, whereas the pore morphology depends on\nthe magnitude of the cooling rate. The obtained results will be in demand in\nstudy of mechanical properties of amorphous metallic foams with a nanoporous\nstructure.",
        "positive": "Phase separation in Fe2CrSi thin films: Thin films of a nominal Fe2CrSi alloy have been deposited by magnetron\nco-sputtering with various heat treatments on MgO and MgAl2O4 substrates. After\nheat treatment, the films were found to decompose into a nearly epitaxial Fe3Si\nfilm with the D0$_3$ structure and Cr3Si precipitates with the A15 structure.\nWe explain the experimental results on the basis of ab initio calculations,\nwhich reveal that this decomposition is energetically highly favorable."
    },
    {
        "anchor": "Raman spectra of BN-nanotubes: Ab-initio and bond-polarizability model\n  calculations: We present it ab-initio calculations of the non-resonant Raman spectra of\nzigzag and armchair BN nanotubes. In comparison, we implement a generalized\nbond-polarizability model where the parameters are extracted from\nfirst-principles calculations of the polarizability tensor of a BN sheet. For\nlight-polarization along the tube-axis, the agreement between model and it\nab-initio spectra is almost perfect. For perpendicular polarization,\ndepolarization effects have to be included in the model in order to reproduce\nthe it ab-initio Raman intensities.",
        "positive": "Spin wave and spin flip in hexagonal LuMnO3 single crystal: Manipulate and control of spin wave and spin flip are crucial for future\ndevelopments of magnonic and spintronic devices. We present that the spin wave\nin hexagonal LuMnO3 single crystal can be selectively excited with laser\npolarization perpendicular to the c-axis of hexagonal LuMnO3 and photon energy\n~ 1.8 eV. The selective excitation of spin wave also suggests that the spin\nflip can be selectively controlled in hexagonal manganites. In addition, the\nphysical origin of spin wave correlated with spin flip in hexagonal manganites\nis discussed."
    },
    {
        "anchor": "Role of Entropy and Structural Parameters in the Spin State Transition\n  of LaCoO$_3$: The spin state transition in LaCoO$_3$ has eluded description for decades\ndespite concerted theoretical and experimental effort. In this study, we\napproach this problem using fully charge self-consistent Density Functional\nTheory + Embedded Dynamical Mean Field Theory (DFT+DMFT). We show from first\nprinciples that LaCoO$_3$ cannot be described by a single, pure spin state at\nany temperature. Instead, we observe a gradual change in the population of\nhigher spin multiplets with increasing temperature, with the high spin\nmultiplets being excited at the onset of the spin state transition followed by\nthe intermediate spin multiplets being excited at the metal insulator\ntransition temperature. We explicitly elucidate the critical role of lattice\nexpansion and oxygen octahedral rotations in the spin state transition. We also\nreproduce, from first principles, that the spin state transition and the\nmetal-insulator transition in LaCoO$_3$ occur at different temperature scales.\nIn addition, our results shed light on the importance of electronic entropy in\ndriving the spin state transition, which has so far been ignored in all first\nprinciples studies of this material.",
        "positive": "Frequency estimate for multicomponent crystalline compounds: Among crystal structures of N-component metal alloys, far fewer examples are\nknown with N>=4 than with N=2 or 3, in apparent contradiction to the\nexponentially growing number of possible combinations of elements. Two effects\ncontribute to this shortfall. Since the N-component composition space resides\nwithin a d-dimensional simplex with d=N-1, the vanishing volume in high\ndimensions reduces the distinct N-component compositions. Additionally, the\nincreasing surface area makes it more probable that stable structures reside on\nthe surface of the simplex (containing fewer than N components) as opposed to\nits interior. Despite their rarity, we propose that the actual number of N=4-\nand 5-component alloys greatly exceeds the number that are currently known.\nSpecific estimates are developed through application of the empirical Miedema\nenthalpy model."
    },
    {
        "anchor": "The Role of Interfacial Inherent Structures in the Fast Crystal Growth\n  from Molten Salts and Metals: Molecular dynamics simulations of the temperature dependent crystal growth\nrates of the salts, NaCl and ZnS, from their melts are reported, along with\nthose of a number of pure metals. The growth rate of NaCl and the FCC-forming\nmetals show little evidence of activated control, while that of ZnS and Fe, a\nBCC forming metal, exhibit activation barriers similar to those observed for\ndiffusion in the melt. Unlike ZnS and Fe, the interfacial inherent structures\nof NaCl and Cu and Ag are found to be crystalline. We calculate the median\ndisplacement between the interfacial liquid and crystalline states and show\nthat this distance is smaller than the cage length, demonstrating that crystal\ngrowth in the fast crystallizers can occur via local vibrations and so largely\navoid the activated kinetics associated with the larger displacements\nassociated with particle transport.",
        "positive": "Scaling and complexity of stress fluctuations associated with smooth and\n  jerky flow in a FeCoNiTiAl high-entropy alloy: Recent observations of jerky flow in high-entropy alloys (HEA) revealed a\nhigh role of self-organization of dislocations in their plasticity. The present\nwork reports first results of investigation of stress fluctuations during\nplastic deformation of a FeCoNiTiAl alloy, examined in a wide temperature range\ncovering both smooth and jerky flow. These fluctuations, which accompany the\noverall deformation behavior representing an essentially slower stress\nevolution controlled by the work hardening, were processed using complementary\napproaches comprising the Fourier spectral analysis, the refined composite\nmultiscale entropy, and multifractal formalisms. The joint analysis at distinct\nscales testified that even a macroscopically smooth plastic flow is accompanied\nwith nonrandom fluctuations, disclosing self-organized dynamics of\ndislocations. Qualitative changes in such a fine-scale \"noise\" were found with\nvarying temperature. The observed diversity is significant for understanding\nthe relationships between different scales of plasticity of HEAs and crystal\nmaterials in general."
    },
    {
        "anchor": "Doped Polyaniline: A Possible Anode for Organic Electronics: Polymer based printable organic thin film transistor (OTFT) is a viable low\ncost alternative to amorphous silicon based thin film transistors and possesses\nlight-weight and flexibility advantage. In this paper, we report on the hole\ninjecting properties of doped PANI in OLED devices using it as an anode. From\nthese results we conclude that hole doped PANI layers can be used as a low\ncontact resistance source and drain electrode material for polymer OTFTs.",
        "positive": "Large Magnetic Moment in Flexoelectronic Silicon at Room Temperature: Time-dependent rotational electric polarizations have been proposed to\ngenerate temporally varying magnetic moments, for example, through a\ncombination of ferroelectric polarization and optical phonons. This phenomenon\nhas been called dynamical multiferroicity, but explicit experimental\ndemonstrations have been elusive to date. Here, we report the detection of a\ntemporal magnetic moment as high as 1.2 mu_B/atom in charge-doped thin film of\nsilicon under flexural strain. We demonstrate that the magnetic moment is\ngenerated by a combination of electric polarization arising from a\nflexoelectronic charge separation along the strain gradient and the deformation\npotential of phonons. The effect can be controlled by adjusting the external\nstrain gradient, doping concentration and dopant, and can be regarded as a\ndynamical multiferroic effect involving flexoelectronics polarization instead\nof ferroelectricity. The discovery of a large magnetic moment in silicon may\nenable the use of non-magnetic and non-ferroelectric semiconductors in various\nmultiferroic and spintronic applications."
    },
    {
        "anchor": "Revisiting Effects of Nitrogen Incorporation and Graphitization on\n  Conductivity of Ultra-nano-crystalline Diamond Films: Detailed structural and electrical properties of ultra-nano-crystalline\ndiamond (UNCD) films grown in H$_\\text{2}$/CH$_\\text{4}$/N$_\\text{2}$ plasma\nwere systematically studied as a function of deposition temperature ($T_d$) and\nnitrogen content ($\\%$ N$_2$) to thoroughly evaluate their effects on\nconductivity. $T_d$ was scanned from 1000 to 1300 K for N$_2$ fixed at 0, 5, 10\nand 20 $\\%$. It was found that even the films grown in the synthetic gas\nmixture with no nitrogen could be made as conductive as 1$-$10$^{-2}$ $\\Omega$\ncm with overall resistivity of all the films tuned over 4 orders of magnitude\nthrough varying growth parameters. On a set of 27 samples, Raman spectroscopy\nand scanning electron microscopy show a progressive and highly reproducible\nfilm material phase transformation, from ultra-nano-crystalline diamond to\nnano-crystalline graphite as deposition temperature increases. The rate of this\ntransformation is heavily dependent on N$_2$ content. Addition of nitrogen\ngreatly increases the amount of $sp^2$ bonded carbon in the films thus\nenhancing the physical connectivity in the GB network that have high electronic\ndensity of states. However, addition of nitrogen greatly slows down\ncrystallization of $sp^2$ phase in the GBs. Therefore, proper balance between\nGB connectivity and crystallinity is the key in conductivity engineering of\n(N)UNCD.",
        "positive": "Effect of UV radiation on the structure of graphene oxide in water and\n  its impact on cytotoxicity and As(III) adsorption: Graphene oxide (GO) is widely used in different applications, however once\nrelease into the environment it can change its structure and affect the\ntransport of important contaminants such as arsenic. In this work we show that\nUV radiation, even in the range of 28-74 uW/cm2 of irradiance up to 120 h of\nexposure, can induce important changes in the structure of graphene oxide, by\neliminating -OH and C=O functional groups. This reduction affected the\nstability of graphene oxide in water by decreasing its zeta potential from 41\nto 37 mV with the increase of the exposure time. Our results showed that after\n24 h of UV exposure, As(III) adsorption capacity decreased from 5 mg/g to 4.7\nmg/g, however after 48 h of irradiation the adsorption increased with time,\nreaching 5.1 mg/g at 120 h under 74 uW/cm2 of irradiation. Computer modelling\nshowed that even a degraded GO structure can have an interaction energy of 53\nkcal/mol with H3AsO3. Furthermore, we observed that despite clear changes in\nsurface composition and particle size, the reduction of graphene oxide\nmaintained a high degree of cytotoxicity since cell viability decreased to 60%\nwith a 50 ug/ml dose; except for the sample irradiated at 74 uW/cm2 for five\ndays, which showed 20% with the same concentration."
    },
    {
        "anchor": "Coherent Control of Photocurrents in Graphene and Carbon Nanotubes: Coherent one photon ($2 \\omega$) and two photon ($ \\omega$) electronic\nexcitations are studied for graphene sheets and for carbon nanotubes using a\nlong wavelength theory for the low energy electronic states. For graphene\nsheets we find that coherent superposition of these excitations produces a\npolar asymmetry in the momentum space distribution of the excited carriers with\nan angular dependence which depends on the relative polarization and phases of\nthe incident fields. For semiconducting nanotubes we find a similar effect\nwhich depends on the square of the semiconducting gap, and we calculate its\nfrequency dependence.\n  We find that the third order nonlinearity which controls the direction of the\nphotocurrent is robust for semiconducting t ubes and vanishes in the continuum\ntheory for conducting tubes. We calculate corrections to these results arising\nfrom higher order crystal field effects on the band structure and briefly\ndiscuss some applications of the theory.",
        "positive": "High-pressure phase transitions and compressibility of wolframite-type\n  tungstates: This paper reports an investigation on the phase diagram and compressibility\nof wolframite-type tungstates by means of x-ray powder diffraction and\nabsorption in a diamond-anvil cell and ab initio calculations. The diffraction\nexperiments show that monoclinic wolframite-type MgWO4 suffers at least two\nphase transitions, the first one being to a triclinic polymorph with a\nstructure similar to that of CuWO4 and FeMoO4-II. The onset of each transition\nis detected at 17.1 and 31 GPa. In ZnWO4 the onset of the monoclinic-triclinic\ntransition has been also found at 15.1 GPa. These findings are supported by\ndensity-functional theory calculations, which predict the occurrence of\nadditional transitions upon further compression. Calculations have been also\nperformed for wolframite-type MnWO4, which is found to have an\nantiferromagnetic configuration. In addition, x-ray absorption and diffraction\nexperiments as well as calculations reveal details of the local-atomic\ncompression in the studied compounds. In particular, below the transition\npressure the ZnO6 and equivalent polyhedra tend to become more regular, whereas\nthe WO6 octahedra remain almost unchanged. Fitting the pressure-volume data we\nobtained the equation of state for the low-pressure phase of MgWO4 and ZnWO4.\nThese and previous results on MnWO4 and CdWO4 are compared with the\ncalculations, being the compressibility of wolframite-type tungstates\nsystematically discussed. Finally Raman spectroscopy measurements and lattice\ndynamics calculations are presented for MgWO4."
    },
    {
        "anchor": "Studies on tuning surface electronic properties of hydrogenated diamond\n  by oxygen functionalization: Ultra-wide bandgap and the absence of shallow dopants are the major\nchallenges in realizing diamond based electronics. However, the surface\nfunctionalization offers an excellent alternative to tune electronic structure\nof diamonds. Herein, we report on tuning the surface electronic properties of\nhydrogenated polycrystalline diamond films through oxygen functionalization.\nThe hydrogenated diamond (HD) surface transforms from hydrophobic to\nhydrophilic nature and the sheet resistance increases from ~ 8 kohms/sq. to\nover 10 Gohms/sq. with progressive ozonation. The conductive atomic force\nmicroscopic (c-AFM) studies reveal preferential higher current conduction on\nselective grain interiors (GIs) than that of grain boundaries confirming the\nsurface charge transfer doping on these HDs. In addition, the local current\nconduction is also found to be much higher on (111) planes as compared to (100)\nplanes on pristine and marginally O-terminated HD. However, there is no current\nflow on the fully O-terminated diamond (OD) surface. Further, X-ray\nphotoelectron spectroscopic (XPS) studies reveal a redshift in binding energy\n(BE) of C1s on pristine and marginally O-terminated HD surfaces indicating\nsurface band bending whilst the BE shifts to higher energy for OD. Moreover,\nXPS analysis also corroborate c-AFM study for the possible charge transfer\ndoping mechanism on the diamond films which results in high current conduction\non GIs of pristine and partially O-terminated HDs.",
        "positive": "Modification of Tin (Sn) Metal Surfaces by Surface Plasmon Polariton\n  Excitation: We report on the modification of tin (Sn) film surfaces under a laser beam\nirradiation that triggers surface plasmon polariton (SPP) excitations. The\nobserved surface features in the form of small raised grains, with well-defined\nrooting, look similar to tin whisker nodules. We attribute the appearance of\nthose features to the field-induced nucleation caused by the SPP related strong\nelectric field. Possible implications of our findings include accelerated-life\ntesting for tin whisker growth-related reliability as well as applications to\nnanoparticle nucleation."
    },
    {
        "anchor": "Coherent gigahertz phonons in Ge$_{2}$Sb$_{2}$Te$_{5}$ phase-change\n  materials: Using $\\approx$40 fs ultrashort laser pulses, we investigate the picosecond\nacoustic response from a prototypical phase change material, thin\nGe$_{2}$Sb$_{2}$Te$_{5}$ (GST) films with various thicknesses. After excitation\nwith a 1.53 eV-energy pulse with a fluence of $\\approx$ 5 mJ/cm$^{2}$, the\ntime-resolved reflectivity change exhibits transient electronic response,\nfollowed by a combination of exponential-like strain and coherent acoustic\nphonons in the gigahertz (GHz) frequency range. The time-domain shape of the\ncoherent acoustic pulse is well reproduced by the use of the strain model by\nThomsen et al. (Phys. Rev. B 34, 4129, 1986). We found that the decay rate (the\ninverse of the relaxation time) of the acoustic phonon both in the amorphous\nand in the crystalline phases decreases as the film thickness increases. The\nthickness dependence of the acoustic phonon decay is well modeled based on both\nphonon-defect scattering and acoustic phonon attenuation at the GST/Si\ninterface, and it is revealed that those scattering and attenuation are larger\nin crystalline GST films than those in amorphous GST films.",
        "positive": "Vector Polarons in a Degenerate Electron System: We consider a one dimensional model of an electron in a doubly (or nearly)\ndegenerate band that interacts with elastic distortions. We show that the\nelectron equations of motion reduce to a set of coupled non-linear Schrodinger\nequations. For the case of interband electron-phonon coupling stemming from\nlocal Jahn-Teller interactions, new multicomponent self-localized polaron\nsolutions --vector polarons-- are described and classified. The phase diagram\nfor the different types of vector polarons in this model is presented. By\ninterpreting the components of the orbital doublet as those of spin-1/2, our\nresults can also be used to describe bound magnetic polarons."
    },
    {
        "anchor": "Raman and fluorescence contributions to resonant inelastic soft x-ray\n  scattering on LaAlO$_3$/SrTiO$_3$ heterostructures: We present a detailed study of the Ti 3$d$ carriers at the interface of\nLaAlO$_3$/SrTiO$_3$ heterostructures by high-resolution resonant inelastic soft\nx-ray scattering (RIXS), with special focus on the roles of overlayer thickness\nand oxygen vacancies. Our measurements show the existence of interfacial Ti\n3$d$ electrons already below the critical thickness for conductivity and an\nincrease of the total interface charge up to a LaAlO$_3$ overlayer thickness of\n6 unit cells before it levels out. By comparing stoichiometric and oxygen\ndeficient samples we observe strong Ti 3$d$ charge carrier doping by oxygen\nvacancies. The RIXS data combined with photoelectron spectroscopy and transport\nmeasurements indicate the simultaneous presence of localized and itinerant\ncharge carriers. However, it is demonstrated that the relative amount of\nlocalized and itinerant Ti $3d$ electrons in the ground state cannot be deduced\nfrom the relative intensities of the Raman and fluorescence peaks in excitation\nenergy dependent RIXS measurements, in contrast to previous interpretations.\nRather, we attribute the observation of either the Raman or the fluorescence\nsignal to the spatial extension of the intermediate state reached in the RIXS\nexcitation process.",
        "positive": "Blending stiffness and strength disorder can stabilize fracture: Quasi-brittle behavior where macroscopic failure is preceded by stable\ndamaging and intensive cracking activity is a desired feature of materials\nbecause it makes fracture predictable. Based on a fiber bundle model with\nglobal load sharing we show that blending strength and stiffness disorder of\nmaterial elements leads to the stabilization of fracture, i.e. samples which\nare brittle when one source of disorder is present, become quasi-brittle as a\nconsequence of blending. We derive a condition of quasi-brittle behavior in\nterms of the joint distribution of the two sources of disorder. Breaking bursts\nhave a power law size distribution of exponent 5/2 without any crossover to a\nlower exponent when the amount of disorder is gradually decreased. The results\nhave practical relevance for the design of materials to increase the safety of\nconstructions."
    },
    {
        "anchor": "Self-Folding and Self-Scrolling Mechanisms of Edge-Deformed Graphene\n  Sheets: A Molecular Dynamics Study: Graphene-based nanofolds (GNFs) are edge-connected 2D stacked monolayers\noriginated from single-layer graphene. Graphene-based nanoscrolls (GNSs) are\nnanomaterials with geometry resembling graphene layers rolled up into a spiral\n(papyrus-like) form. Both GNSs and GNFs structures induce significant changes\nin the mechanical and optoelectronic properties of single-layer graphene,\naggregating new functionalities in carbon-based applications. Here, we carried\nour fully atomistic reactive (ReaxFF) molecular dynamics simulations to study\nthe self-folding and self-scrolling of edge-deformed graphene sheets. We\nadopted initial armchair edge-scrolled graphene (AESG($\\phi$,$\\theta$))\nstructures with similar (or different) twist angles ($\\phi$,$\\theta$) in each\nedge, mimicking the initial configuration that was experimentally developed to\nform biscrolled sheets. Results showed that AESG(0,$2\\pi$) and\nAESG(2$\\pi$,$2\\pi$) evolved to single-folded and two-folded fully stacked\nmorphologies, respectively. As a general trend, for twist angles higher than\n$2\\pi$, the self-deformation process of AESG morphologies yields GNSs. Edge\ntwist angles lower than $\\pi$ are not enough for triggering the\nself-deformation processes. In the AESG(0,3$\\pi$) and AESG(3$\\pi$,3$\\pi$)\ncases, after a relaxation period, their morphology transition towards GNS\noccurred rapidly. In the AESG(3$\\pi$,3$\\pi$) dynamics, a metastable biscroll\nwas formed by the interplay between the left- and right-sided partial scrolling\nin forming a unique GNS. At high-temperature perturbations, the edge folding\nand scrolling transitions to GNFs and GNSs occurred within the ultrafast\nperiod. Remarkably, the AESG(2$\\pi$,3$\\pi$) evolved to a dual state that\ncombines folded and scrolled structures in a temperature-independent process.",
        "positive": "Bulk moduli of PbS$_{x}$Se$_{1-x}$, PbS$_{x}$Te$_{1-x}$ and\n  PbSe$_{x}$Te$_{1-x}$ from a thermodynamical model compared to generalized\n  gradient approximation approach: Very recently, first-principle technique of full-potential linearized\naugmented plane-wave method, by using for exchange-correlation potential the\ngeneralized gradient approximation (GGA), was employed for the study of the\nlead chalcogenide semiconductors' alloys PbS$_{x}$Se$_{1-x}$,\nPbS$_{x}$Te$_{1-x}$ and PbSe$_{x}$Te$_{1-x}$. These density functional\ncalculations led to the determination of structural, electronic and optical\nproperties, including the values of lattice constants and bulk moduli as a\nfunction of composition. Here, we investigate the latter properties, but by\nemploying a thermodynamical model which has been suggested for the formation\nand migration of defects in solids including several recent applications in\nsemiconductors. The following crucial difference emerges when comparing the\npresent results with those deduced by density functional calculations: Among\nthe alloys studied, GGA calculations identify that PbS$_{x}$Te$_{1-x}$ exhibits\nthe most evident non-linear variation of the bulk modulus versus the\ncomposition, while according to the thermodynamical model such an evident\nnon-linear behavior -and maybe somewhat stronger- is also expected for\nPbSe$_{x}$Te$_{1-x}$. A tentative origin of this diversity is discussed."
    },
    {
        "anchor": "First principles second harmonic generation of transition metal\n  dichalcogenides and boron nitride alloys: from monolayers and nanotubes to\n  Haeckelites and Schwarzites: In order to shed light on the second harmonic generation (SHG) of new 2-D\nsystems, first principles methods are used to calculate the second order\nsusceptibility \\chi(2) for different types of layered alloys such as monolayers\nof transition metal dichalcogenide (TMD) alloys, TMD Haeckelite alloys,\nnanotubes of TMD alloys, hexagonal boron nitride (h-BN) systems which include\nBxNyCz alloys, BN and BNC2 nanotubes, BxNxCy Haeckelites and BN Schwarzites\n(porous BN). It is found that the tungsten based alloys possess higher \\chi(2)\nthan Mo based at high photon energies, but at low energies, one type of MoSSe\ndominates. The hypothetical TMD Haeckelites NbSSe and Nb0.5Ta0.5S2 reveal the\nhighest \\chi(2) of all the calculated structures. Zigzag TMD alloy nanotubes\nshow higher \\chi(2) as the diameter is reduced and approximate to the monolayer\nfor big diameters. BNC alloys exhibit a higher \\chi(2) than the h-BN monolayer\nand are comparable to TMD alloys, except for one case which doubles its\nintensity. The BN tubes show an increase of \\chi(2) as the diameter decreases,\nsimilarly to the TMD nanotubes. BxNxCy Haeckelites possess a very high \\chi(2)\nand may shed light on the role of extended defects in nonlinear optical\nproperties. One of the BN Schwarzites exhibits a higher \\chi(2) than already\nknown 3-D materials.",
        "positive": "Void defect induced magnetism and structure change of carbon\n  materials-1, Graphene nano ribbon: Void defect is a possible origin of ferromagnetic like feature of pure carbon\nmaterial. Applying density functional theory to void defect induced graphene\nnano ribbon (GNR), a detailed relationship between multiple spin state and\nstructure change was studied. An equitorial triangle of an initial initial void\nhaving six electrons is distorted to isosceles triangle by rebonding carbon\natoms. Among possible spin states, the most stable state was Sz=2/2. The case\nof Sz=4/2 is remarkable that initial flat ribbon turned to three dimentional\ncurled one having highly polarized spin configuration at ribbon edges. Total\nenergy of Sz=4/2 was very close to that of Sz=2/2, which suggests coexistence\nof flat and curled ribbons. As a model of three dimensional graphite, bilayered\nAB stacked GNR was analyzed. Spin distribution was limited to the void created\nlayer. Distributed void triangle show 60 degree clockwise rotation for\ndifferrent site void, which was consistent with experimental observation using\nthe scanning tunneling microscope. (To be published on Journal of the Magnetic\nSociety of Japan, 2021 )"
    },
    {
        "anchor": "Ultrastrong adhesion in the contact with thin elastic layers on a rigid\n  foundation: In the present short note, we generalize simple approximate\nJohnson-Jaffar-Barber solutions for the indentation by a rigid punch of a thin\nelastic layer on a rigid foundation to the case of adhesion. This could be an\ninteresting geometry for an adhesive system, a limit case of the more general\nclass of layered systems, or FGMs (Functionally Graded Materials). We show that\nultrastrong adhesion (up to theoretical strength) can be reached both in line\ncontact or in axisymmetric contact for thin layers (typically of nanoscale\nsize), which suggests a new possible strategy for \"optimal adhesion\". In\nparticular, in line contact adhesion enhancement occurs as an increase of the\nactual pull-off force, while in axisymmetric case the latter is apparently very\nclose to the classical JKR case. However, it appears in closer examination that\nalso for axisymmetric case, the enhancement occurs by reducing the size of\ncontact needed to sustain the pull-off force. These effects are further\nenhanced by Poisson's ratio effects in the case of nearly incompressible layer.",
        "positive": "On the room temperature ferroelectricity of hydrogen-bonded charge\n  transfer crystals: We present a theoretical investigation of the anomalous ferroelectricity of\nmixed-stack charge transfer molecular crystals, based on the Peierls-Hubbard\nmodel, and first principles calculations for its parameterization. This\napproach is first validated by reproducing the temperature-induced transition\nand the electronic polarization of TTF-CA, and then applied to a novel series\nof hydrogen-bonded crystals, for which room temperature ferroelectricity has\nrecently been claimed. Our analysis shows that the hydrogen-bonded systems\npresent a very low degree of charge transfer and hence support a very small\npolarization. A critical re-examination of experimental data supports our\nfindings, shedding doubts on the ferroelectricity of these systems. More\ngenerally, our modelling allows the rationalization of general features of the\nferroelectric transition in charge transfer crystals, and suggests design\nprinciples for materials optimization."
    },
    {
        "anchor": "Magnetic anisotropy of FePt: effect of lattice distortion and chemical\n  disorder: We perform first principles calculations of the magnetocrystalline anisotropy\nenergy in the five L10 FePt samples studied experimentally by Ding et al. [J.\nApp. Phys. 97, 10H303 (2005)]. The effect of temperature-induced spin\nfluctuations is estimated by scaling the MAE down according to previous\nLangevin dynamics simulations. Including chemical disorder as given in\nexperiment, the experimental correlation between MAE and lattice mismatch is\nqualitatively well reproduced. Moreover we determine the chemical order\nparameters that reproduce exactly the experimental MAE of each sample. We\nconclude that the MAE is determined by the chemical disorder rather than by\nlattice distortion.",
        "positive": "Melting of hexane monolayers adsorbed on graphite: the role of domains\n  and defect formation: We present the first large-scale molecular dynamics simulations of hexane on\ngraphite that completely reproduces all experimental features of the melting\ntransition. The canonical ensemble simulations required and used the most\nrealistic model of the system: (i) fully atomistic representation of hexane;\n(ii) explicit site-by-site interaction with carbon atoms in graphite; (iii)\nCHARMM force field with carefully chosen adjustable parameters of non-bonded\ninteraction; (iv) numerous $\\ge$ 100 ns runs, requiring a total computation\ntime of ca. 10 CPU-years. This has allowed us to determine correctly the\nmechanism of the transition: molecular reorientation within lamellae without\nperturbation of the overall adsorbed film structure. We observe that the melted\nphase has a dynamically reorienting domain-type structure whose orientations\nreflect that of graphite."
    },
    {
        "anchor": "Lattice dynamics and ultrafast energy flow between electrons, spins, and\n  phonons in a 3d ferromagnet: The ultrafast dynamics of magnetic order in a ferromagnet are governed by the\ninterplay between electronic, magnetic and lattice degrees of freedom. In order\nto obtain a microscopic understanding of ultrafast demagnetization, information\non the response of all three subsystems is required. A consistent description\nof demagnetization and microscopic energy flow, however, is still missing.\nHere, we combine a femtosecond electron diffraction study of the ultrafast\nlattice response of nickel to laser excitation with ab initio calculations of\nthe electron-phonon interaction and energy-conserving atomistic spin dynamics\nsimulations. Our model is in agreement with the observed lattice dynamics and\npreviously reported electron and magnetization dynamics. Our approach reveals\nthat the spin system is the dominating heat sink in the initial few hundreds of\nfemtoseconds and implies a transient non-thermal state of the spins. Our\nresults provide a clear picture of the microscopic energy flow between\nelectronic, magnetic and lattice degrees of freedom on ultrafast timescales and\nconstitute a foundation for theoretical descriptions of demagnetization that\nare consistent with the dynamics of all three subsystems.",
        "positive": "X-ray Nano-imaging of Defects in Thin Film Catalysts via Cluster\n  Analysis: Functional properties of transition-metal oxides strongly depend on\ncrystallographic defects. In transition-metal-oxide electrocatalysts such as\nSrIrO3 (SIO), crystallographic lattice deviations can affect ionic diffusion\nand adsorbate binding energies. Scanning x-ray nanodiffraction enables imaging\nof local structural distortions across an extended spatial region of thin\nsamples. Line defects remain challenging to detect and localize using\nnanodiffraction, due to their weak diffuse scattering. Here we apply an\nunsupervised machine learning clustering algorithm to isolate the low-intensity\ndiffuse scattering in as-grown and alkaline-treated thin epitaxially strained\nSIO films. We pinpoint the defect locations, find additional strain variation\nin the morphology of electrochemically cycled SIO, and interpret the defect\ntype by analyzing the diffraction profile through clustering. Our findings\ndemonstrate the use of a machine learning clustering algorithm for identifying\nand characterizing hard-to-find crystallographic defects in thin films of\nelectrocatalysts and highlight the potential to study electrochemical reactions\nat defect sites in operando experiments."
    },
    {
        "anchor": "Novel Rubidium Poly-Nitrogen Materials at High Pressure: First-principles crystal structure search is performed to predict novel\nrubidium poly-nitrogen materials at high pressure by varying the stoichiometry,\ni. e. relative quantities of the constituent rubidium and nitrogen atoms. Three\ncompounds of high nitrogen content, RbN_{5}, RbN_{2}, and Rb_{4}N_{6}, are\ndiscovered. Rubidium pentazolate (RbN5) becomes thermodynamically stable at\npressures above \\unit[30]{GPa}. The charge transfer from Rb to N atoms enables\naromaticity in cyclo-N_{^{_{5}}}^{-} while increasing the ionic bonding in the\ncrystal. Rubidium pentazolate can be synthesized by compressing rubidium azide\n(RbN3) and nitrogen (N2) precursors above \\unit[9.42]{GPa}, and its\nexperimental discovery is aided by calculating the Raman spectrum and\nidentifying the features attributed to N_{^{_{5}}}^{-} modes. The two other\ninteresting compounds, RbN2 containing infinitely-long single-bonded nitrogen\nchains, and Rb_{4}N_{6} consisting of single-bonded N_{6} hexazine rings,\nbecome thermodynamically stable at pressures exceeding \\unit[60]{GPa}. In\naddition to the compounds with high nitrogen content, Rb_{3}N_{3}, a new\ncompound with 1:1 RbN stoichiometry containing bent N_{3} azides is found to\nexist at high pressures.",
        "positive": "Strong localization of oxidized Co3+ state in cobalt-hexacyanoferrate: Secondary batteries are important energy storage devices for a mobile\nequipment, an electric car, and a large-scale energy storage. Nevertheless,\nvariation of the local electronic state of the battery materials in the charge\n(or oxidization) process are still unclear. Here, we investigated the local\nelectronic state of cobalt-hexacyanoferrate (Na$_x$Co[Fe(CN)$_6$]$_{0.9}$), by\nmeans of resonant inelastic X-ray scattering (RIXS) with high energy resolution\n(~100 meV). The L-edge RIXS is one of the most powerful spectroscopic technique\nwith element- and valence-selectivity. We found that the local electronic state\naround Co$^{2+}$ in the partially-charged\nNa$_{1.1}$Co$^{2+}$$_{0.5}$Co$^{3+}$$_{0.5}$[Fe$^{2+}$(CN)$_6$]$_{0.9}$ film (x\n= 1.1) is the same as that of the discharged\nNa$_{1.6}$Co$^{2+}$[Fe$^{2+}$(CN)$_6$]$_{0.9}$ film (x = 1.6) within the energy\nresolution, indicating that the local electronic state around Co$^{2+}$ is\ninvariant against the partial oxidization. In addition, the local electronic\nstate around the oxidized Co$^{3+}$ is essentially the same as that of the\nfully-charged film\nCo$^{3+}$[Fe$^{2+}$(CN)$_6$]$_{0.3}$[Fe$^{3+}$(CN)$_6$]$_{0.6}$ (x = 0.0) film.\nSuch a strong localization of the oxidized Co$^{3+}$ state is advantageous for\nthe reversibility of the redox process, since the localization reduces extra\nreaction within the materials and resultant deterioration."
    },
    {
        "anchor": "InterPhon: Ab initio Interface Phonon Calculations within a 3D\n  Electronic Structure Framework: This work provides the community with an easily executable open-source Python\npackage designed to automize the evaluation of Interfacial Phonons (InterPhon).\nIts strategy of arbitrarily defining the interfacial region and periodicity\nalleviates the excessive computational cost in applying ab initio phonon\ncalculations to interfaces and enables efficient extraction of interfacial\nphonons. InterPhon makes it possible to apply all of the phonon-based\npredictions that have been available for bulk systems, to interfacial systems.\nThe first example, in which this package was applied to InAs surfaces,\ndemonstrates a systematic structure search for unexplored surface\nreconstructions, navigated by the imaginary mode of surface phonons. It\neventually explains the anisotropic surface vibrations of the polar crystal.\nThe second example, involving oxygen adsorption on Cu, reveals\nadsorption-induced vibrational change and its contribution to energetic\nstability. The third example, on a Si/GaAs interface, shows distinct\nvibrational patterns depending on interfacial structures. It leads to a\nprediction regarding the structural transition of interfaces and unveils the\nprocessing conditions for spontaneous growth of GaAs nanowires on Si.\nHigh-level automation in InterPhon will be of great help in elucidating\ninterfacial atomic dynamics and in implementing an automated computational\nworkflow for diverse interfacial systems.",
        "positive": "X-ray Reflectivity Studies of Atomic-level Surface-segregation in a\n  Liquid Eutectic Alloy of AuSn: X-ray reflectivity studies reveal atomic-level surface-segregation at the\nfree surface of the eutectic Au71Sn29 liquid alloy. The surface-segregation\nextends up to three layers, in which the top layer is almost a pure monolayer\nof Sn, the second layer is almost a pure monolayer of Au and the third layer\nappears to be slightly enhanced in Au. Although the surface-segregation\nconcentration profiles can be qualitatively accounted for by the theories of\nDefay-Prigogine and Strohl-King, they cannot satisfactorily account for the\nmeasured surface tension.\n  PACS numbers: 61.20.-p, 61.10.-i, 68.03.-g"
    },
    {
        "anchor": "Alternative Buffer-Layers for the Growth of SrBi2Ta2O9 on Silicon: In this work we investigate the influence of the use of YSZ and CeO2/YSZ as\ninsulators for Metal- Ferroelectric-Insulator-Semiconductor (MFIS) structures\nmade with SrBi2Ta2O9 (SBT). We show that by using YSZ only the a-axis oriented\nPyrochlore phase could be obtained. On the other hand the use of a CeO2/YSZ\ndouble-buffer layer gave a c-axis oriented SBT with no amorphous SiO2 inter-\ndiffusion layer. The characteristics of MFIS diodes were greatly improved by\nthe use of the double buffer. Using the same deposition conditions the memory\nwindow could be increased from 0.3 V to 0.9 V. From the piezoelectric response,\nnano-meter scale ferroelectric domains could be clearly identified in SBT thin\nfilms.",
        "positive": "Strain-induced energy band gap opening in two-dimensional bilayered\n  silicon film: This work presents a theoretical study of the structural and electronic\nproperties of bilayered silicon films under in-plane biaxial strain/stress\nusing density functional theory. Atomic structures of the two-dimensional\nsilicon films are optimized by using both the local-density approximation and\ngeneralized gradient approximation. In the absence of strain/stress, five\nbuckled hexagonal honeycomb structures of the bilayered silicon film have been\nobtained as local energy minima and their structural stability has been\nverified. These structures present a Dirac-cone shaped energy band diagram with\nzero energy band gaps. Applying tensile biaxial strain leads to a reduction of\nthe buckling height. Atomically flat structures with zero bucking height have\nbeen observed when the AA-stacking structures are under a critical biaxial\nstrain. Increase of the strain between 10.7% ~ 15.4% results in a band-gap\nopening with a maximum energy band gap opening of ~168.0 meV obtained when\n14.3% strain is applied. Energy band diagram, electron transmission efficiency,\nand the charge transport property are calculated."
    },
    {
        "anchor": "Comment on ``Coherent Control of a V-Type Three-Level System in a Single\n  Quantum Dot'': This is a Comment on Phys. Rev. Lett., {\\bf 95}, 187404 (2005)",
        "positive": "Wave mechanics in media pinned at Bravais lattice points: The propagation of waves through microstructured media with periodically\narranged inclusions has applications in many areas of physics and engineering,\nstretching from photonic crystals through to seismic metamaterials. In the\nhigh-frequency regime, modelling such behaviour is complicated by multiple\nscattering of the resulting short waves between the inclusions. Our aim is to\ndevelop an asymptotic theory for modelling systems with arbitrarily-shaped\ninclusions located on general Bravais lattices. We then consider the limit of\npoint-like inclusions, the advantage being that exact solutions can be obtained\nusing Fourier methods, and go on to derive effective medium equations using\nasymptotic analysis. This approach allows us to explore the underlying reasons\nfor dynamic anisotropy, localisation of waves, and other properties typical of\nsuch systems, and in particular their dependence upon geometry. Solutions of\nthe effective medium equations are compared with the exact solutions, shedding\nfurther light on the underlying physics. We focus on examples that exhibit\ndynamic anisotropy as these demonstrate the capability of the asymptotic theory\nto pick up detailed qualitative and quantitative features."
    },
    {
        "anchor": "Graphene Segregated on Ni surfaces and Transferred to Insulators: We report an approach to synthesize high quality graphene by surface\nsegregation and substrate transfer. Graphene was segregated from Ni surface\nunder the ambient pressure by dissolving carbon in Ni at high temperatures\nfollowed by cooling down with various rates. Different cooling rates led to\ndifferent segregation behaviors, strongly affecting the thickness and quality\nof the graphene films. Electron microscopy and Raman spectroscopy indicated\nthat the graphene films synthesized with medium cooling rates have high quality\ncrystalline structure and well-controlled thicknesses. The graphene films were\ntransferred to insulating substrates by wet etching and found to maintain their\nhigh quality.",
        "positive": "High pressure computational search of trivalent lanthanide di-nitrides: Transition metal nitrides have attracted much interest of the scientific\ncommunity for their intriguing properties and technological applications. Here\nwe focus on yttrium dinitride (YN$_{2}$) and its formation and structural\ntransition under pressure. We employed a fixed composition USPEX search to find\nthe most stable polymorphs. We choose yttrium as a proxy for the lanthanide\nseries because it has only $+3$ oxidation state, contrary to most transition\nmetals. We then computed thermodynamic and dynamical stability of these\nstructures compared to the decomposition reactions and we found that the\ncompound undergoes two structural transitions, the latter showing the formation\nN$_{4}$ chains. A closer look into the nature of the nitrogen bonding showed\nthat in the first two structures, where nitrogen forms dimers, the bond length\nis intermediate between that of a single bond and that of a double bond, making\nit hard to rationalize the proper oxidation state configuration for YN$_{2}$.\nIn the latter structure where there is the formation of N$_{4}$ chains, the\nbond lengths increase significantly, up to a value that can be justified as a\nsingle bond. Finally, we also studied the electronic structure and the\ndynamical stability of the structures we found."
    },
    {
        "anchor": "Modeling of ion-implanted atoms diffusion during the epitaxial growth of\n  the layer: The equation of impurity diffusion due to formation, migration, and\ndissolution of the pairs \"impurity atom - intrinsic point defect\" taking into\naccount the nonuniform distributions of nonequilibrium point defects and drift\nof the pairs in the field of elastic stresses is presented in the coordinate\nsystem associated with the moving surface of the growing epitaxial layer. The\nanalytical solution of this equation for the low fluence ion implantation has\nbeen obtained.",
        "positive": "Memory effects in non-adiabatic molecular dynamics at metal surfaces: We study the effect of temporal correlation in a Langevin equation describing\nnon-adiabatic dynamics at metal surfaces. For a harmonic oscillator the\nLangevin equation preserves the quantum dynamics exactly and it is demonstrated\nthat memory effects are needed in order to conserve the ground state energy of\nthe oscillator. We then compare the result of Langevin dynamics in a harmonic\npotential with a perturbative master equation approach and show that the\nLangevin equation gives a better description in the non-perturbative range of\nhigh temperatures and large friction. Unlike the master equation, this approach\nis readily extended to anharmonic potentials. Using density functional theory\nwe calculate representative Langevin trajectories for associative desorption of\nN$_2$ from Ru(0001) and find that memory effects lowers the dissipation of\nenergy. Finally, we propose an ab-initio scheme to calculate the temporal\ncorrelation function and dynamical friction within density functional theory."
    },
    {
        "anchor": "Pre-Stressed Sub-Surface Contribution on Bulk Diffusion in Metallic\n  Solids: Our recent modelling works and corresponding numerical simulations realized\nto describe the UO2 oxidation processes confirm the theory showing that an\napplied mechanical strain can strongly affect the local oxygen diffusion in a\nstressed solid. This result allows us to assume that stress field, previously\napplied at the surface of a metallic sample on several microns, will delay the\ndegradation during its oxidation. Considering this hypothesis, we implemented a\nFEM simulation code developed in our laboratory to numerically investigate some\ndifferent stress fields applied on a sample sub-surface, that might\nsignificantly modify the volume diffusion of oxygen during the oxidation\nprocess. The results of our simulations are presented and discussed from the\nperspective to study the consequences of a surface mechanical treatment on the\ndurability of a metallic material.",
        "positive": "Zero-temperature phase diagram of D$_2$ physisorbed on graphane: We determined the zero-temperature phase diagram of D$_2$ physisorbed on\ngraphane using the diffusion Monte Carlo method. The substrate used was\nC-graphane, an allotropic form of the compound that has been experimentally\nobtained through hydrogenation of graphene. We found that the ground state is\nthe $\\delta$ phase, a commensurate structure observed experimentally when D$_2$\nis adsorbed on graphite, and not the registered $\\sqrt 3 \\times \\sqrt 3$\nstructure characteristic of H$_2$ on the same substrate."
    },
    {
        "anchor": "Nanoscale Sn off-centering behind low thermal conductivity in SnSe\n  thermoelectric: The local atomic structure of SnSe was characterized across its\northorhmbic-to-orthorhombic structural phase transition using x-ray pair\ndistribution function analysis. Substantial Sn off-centering distortions\npersist in the high symmetry high temperature phase, with symmetry different\nfrom that of ordered distortions below the transition. The analysis implies\nthat the transition is neither order-disorder nor displacive, but rather a\ncomplex crossover where the character of coupling changes from 3D-like at low\ntemperature to 2D-like at high temperature. Robust ferro-coupled SnSe\nintra-layer distortions suggest a ferroelectric-like instability as the driving\nforce. Complex local Sn off-centering is integral to the ultra-low lattice\nthermal conductivity mechanism in SnSe.",
        "positive": "Hybrid III-V/SiGe solar cells on Si substrates and porous Si substrates: A tandem GaAsP/SiGe solar cell has been developed employing group-IV reverse\nbuffer layers grown on silicon substrates with a subsurface porous layer.\nReverse buffer layers facilitate a reduction in the threading dislocation\ndensity with limited thicknesses, but ease the appearance of cracks, as\nobserved in previous designs grown on regular Si substrates. In this new\ndesign, a porous silicon layer has been incorporated close to the substrate\nsurface. The ductility of this layer helps repress the propagation of cracks,\ndiminishing the problems of low shunt resistance and thus improving solar cell\nperformance. The first results of this new architecture are presented here."
    },
    {
        "anchor": "Thermally-Enhanced Fr\u00f6hlich Coupling in SnSe: To gain insight into the peculiar temperature dependence of the\nthermoelectric material SnSe, we employ many-body perturbation theory and\nexplore the influence of the electron-phonon interaction on its electronic and\ntransport properties. We show that a lattice dynamics characterized by soft\nhighly-polar phonons induces a large thermal enhancement of the Fr\\\"ohlich\ninteraction. We account for these phenomena in ab-initio calculations of the\nphotoemission spectrum and electrical conductivity at finite temperature,\nunraveling the mechanisms behind recent experimental data. Our results reveal a\ncomplex interplay between lattice thermal expansion and Fr\\\"ohlich coupling,\nproviding a new rationale for the in-silico prediction of transport\ncoefficients of high-performance thermoelectrics.",
        "positive": "Phase segregation in Mg$_{x}$Zn$_{1-x}$O probed by optical absorption\n  and photoluminescence at high pressure: The appearance of segregated wurtzite Mg$_x$Zn$_{1-x}$O with low Mg content\nin thin films with $x>0.3$ affected by phase separation, cannot be reliably\nprobed with crystallographic techniques owing to its embedded nanocrystalline\nconfiguration. Here we show a high-pressure approach which exploits the\ndistinctive behaviors under pressure of wurtzite Mg$_x$Zn$_{1-x}$O thin films\nwith different Mg contents to unveil phase segregation for $x>0.3$. By using\nambient conditions photoluminescence (PL), and with optical absorption and PL\nunder high pressure for $x=0.3$ we show that the appearance of a segregated\nwurtzite phase with a magnesium content of x $\\sim$ 0.1 is inherent to the\nwurtzite and rock-salt phase separation. We also show that the presence of\nsegregated wurtzite phase in oversaturated thin films phase is responsible for\nthe low-energy absorption tail observed above $x=0.3$ in our Mg$_x$Zn$_{1-x}$O\nthin films. Our study has also allowed us to extend the concentration\ndependence of the pressure coefficient of the band gap from the previous limit\nof $x$ = 0.13 to $x \\approx 0.3$ obtaining d$E_g$/d$P$ = 29 meV/GPa for\nwurtzite with $x \\approx 0.3$ and 25 meV/GPa for the segregated $x\\approx 0.09$\nwurtzite phase."
    },
    {
        "anchor": "Line and Point Defects in MoSe2 Bilayer Studied by Scanning Tunneling\n  Microscopy and Spectroscopy: Bilayer (BL) MoSe2 films grown by molecular-beam epitaxy (MBE) are studied by\nscanning tunneling microscopy and spectroscopy (STM/S). Similar to monolayer\n(ML) films, networks of inversion domain boundary (DB) defects are observed\nboth in the top and bottom layers of BL MoSe2, and often they are seen\nspatially correlated such that one is on top of the other. There are also\nisolated ones in the bottom layer without companion in the top-layer and are\ndetected by STM/S through quantum tunneling of the defect states through the\nbarrier of the MoSe2 ML. Comparing the DB states in BL MoSe2 with that of ML\nfilm reveals some common features as well as differences. Quantum confinement\nof the defect states is indicated. Point defects in BL MoSe2 are also observed\nby STM/S, where ionization of the donor defect by the tip-induced electric\nfield is evidenced. These results are of great fundamental interests as well as\npractical relevance of devices made of MoSe2 ultrathin layers.",
        "positive": "Active learning of reactive Bayesian force fields: Application to\n  heterogeneous hydrogen-platinum catalysis dynamics: Accurate modeling of chemically reactive systems has traditionally relied on\neither expensive ab initio approaches or flexible bond-order force fields such\nas ReaxFF that require considerable time, effort, and expertise to\nparameterize. Here, we introduce FLARE++, a Bayesian active learning method for\ntraining reactive many-body force fields on the fly during molecular dynamics\n(MD) simulations. During the automated training loop, the predictive\nuncertainties of a sparse Gaussian process (SGP) force field are evaluated at\neach timestep of an MD simulation to determine whether additional ab initio\ndata are needed. Once trained, the SGP is mapped onto an equivalent and much\nfaster model that is polynomial in the local environment descriptors and whose\nprediction cost is independent of the training set size. We apply our method to\na canonical reactive system in the field of heterogeneous catalysis, hydrogen\nsplitting and recombination on a platinum (111) surface, obtaining a trained\nmodel within three days of wall time that is twice as fast as a recent Pt/H\nReaxFF force field and considerably more accurate. Our method is fully open\nsource and is expected to reduce the time and effort required to train fast and\naccurate reactive force fields for complex systems."
    },
    {
        "anchor": "The Effect of Intra-Layer Bonding on Electron-Optical Phase Images of\n  Few-Layer WSe2: The quantitative analysis of electron-optical phase images recorded using\noff-axis electron holography often relies on the use of computer simulations of\nelectron propagation through a sample. However, simulations that make use of\nthe independent atom approximation are known to overestimate experimental phase\nshifts by approximately 10%, as they neglect bonding effects. Here, we compare\nexperimental and simulated phase images for few-layer WSe2 . We show that a\ncombination of pseudopotentials and all-electron density functional theory\ncalculations can be used to obtain accurate mean electron phases, as well as\nimproved atomic-resolution spatial distribution of the electron phase. The\ncomparison demonstrates a perfect contrast match between experimental and\nsimulated atomic-resolution phase images for a sample of precisely know\nthickness. The low computational cost of this approach makes it suitable for\nthe analysis of large electronic systems, including defects, substitutional\natoms and material interfaces.",
        "positive": "Magnetic properties of the RbMnPO4 zeolite-ABW type material: a\n  frustrated zigzag spin chain: The crystal structure and magnetic properties of the RbMnPO4 zeolite-ABW type\nmaterial have been studied by temperature-dependent neutron powder diffraction,\nlow temperature magnetometry and heat capacity measurements. RbMnPO4 represents\na rare example of a weak ferromagnetic polar material, containing Mn2+ ions\nwith TN = 4.7 K. The neutron powder diffraction pattern recorded at T = 10 K\nshows that the compound crystallizes in the chiral and polar monoclinic space\ngroup P21 (No. 4) with the unit-cell parameters: a = 8.94635(9) {\\AA}, b =\n5.43415(5) {\\AA}, c = 9.10250(8) {\\AA} and beta = 90.4209(6){\\deg}. A close\ninspection of the crystal structure of RbMnPO4 shows that this material\npresents two different types of zigzag chains running along the b axis. This is\na unique feature among the zeolite-ABW type materials exhibiting the P21\nsymmetry. At low temperature, RbMnPO4 exhibits a canted antiferromagnetic\nstructure characterized by the propagation vector k1 = 0 resulting in the\nmagnetic symmetry P21. The magnetic moments lie mostly along the b axis with\nthe ferromagnetic component being in the ac plane. Due to the geometrical\nfrustration present in this system, an intermediate phase appears within the\ntemperature range 4.7 - 5.1 K characterized by the propagation vector k2 = (kx,\n0, kz) with kx/kz = 2. This ratio is reminiscent of the multiferroic phase of\nthe orthorhombic RMnO3 phases (R = rare earth). This suggests that RbMnPO4\ncould present some multiferroic properties at low temperature. Our density\nfunctional calculations confirm the presence of magnetic frustration, which\nexplains this intermediate incommensurate phase. Taking into account the\nstrongest magnetic interactions, we are able to reproduce the magnetic\nstructure observed experimentally at low temperature."
    },
    {
        "anchor": "First Principles Calculation of Elastic Properties of Solid Argon at\n  High Pressures: The density and the elastic stiffness coefficients of fcc solid argon at high\npressures from 1 GPa up to 80 GPa are computed by first-principles\npseudopotential method with plane-wave basis set and the generalized gradient\napproximation (GGA). The result is in good agreement with the experimental\nresult recently obtained with the Brillouin spectroscopy by Shimizu et al.\n[Phys. Rev. Lett. 86, 4568 (2001)]. The Cauchy condition was found to be\nstrongly violated as in the experimental result, indicating large contribution\nfrom non-central many-body force. The present result has made it clear that the\nstandard density functional method with periodic boundary conditions can be\nsuccessfully applied for calculating elastic properties of rare gas solids at\nhigh pressures in contrast to those at low pressures where dispersion forces\nare important.",
        "positive": "Magnetic Properties of New Triangular Lattice Magnets\n  A${_4}$B'B${_2}$O$_{12}$: The geometrically frustrated two dimensional triangular lattice magnets\nA${_4}$B'B${_2}$O$_{12}$ (A = Ba, Sr, La; B' = Co, Ni, Mn; B = W, Re) have been\nstudied by x-ray diffraction, AC and DC susceptibilities, powder neutron\ndiffraction, and specific heat measurements. The results reveal that (i) the\nsamples containing Co$^{2+}$ (effective spin-1/2) and Ni$^{2+}$ (spin-1) ions\nwith small spin numbers exhibit ferromagnetic (FM) ordering while the sample\ncontaining Mn$^{2+}$ (spin-5/2) ions with a large spin number exhibits\nantiferromagnetic (AFM) ordering. We ascribe these spin number manipulated\nground states to the competition between the AFM B'-O-O-B' and FM B'-O-B-O-B'\nsuperexchange interactions; (ii) the chemical pressure introduced into the Co\ncontaining samples through the replacement of different size ions on the A site\nfinely tunes the FM ordering temperature of the system. We attribute this\neffect to the modification of the FM interaction strength induced by the change\nof the O-B-O angle through chemical pressure."
    },
    {
        "anchor": "Introduction of Zr in nanometric periodic Mg/Co multilayers: We study the introduction of a third material, namely Zr, within a nanometric\nperiodic Mg/Co structure designed to work as optical component in the extreme\nUV (EUV) spectral range. Mg/Co, Mg/Zr/Co, Mg/Co/Zr and Mg/Zr/Co/Zr multilayers\nare designed, then characterized in terms of structural quality and optical\nperformances through X-ray and EUV reflectometry measurements respectively. For\nthe Mg/Co/Zr structure, the reflectance value is equal to 50% at 25.1 nm and\n45deg of grazing incidence and reaches 51.3% upon annealing at 200deg C.\nMeasured EUV reflectivity values of tri-layered systems are discussed in terms\nof material order within a period and compared to the predictions of the\ntheoretical model of Larruquert. Possible applications are pointed out.",
        "positive": "Screening of generalized stacking fault energies, surface energies and\n  intrinsic ductile potency of refractory multicomponent alloys: Body-centered cubic (bcc) refractory multicomponent alloys are of great\ninterest due to their remarkable strength at high temperatures. Meanwhile,\nfurther optimizing the chemical compositions of these alloys to achieve a\ncombination of high strength and room-temperature ductility remains\nchallenging, which would require systematic predictions of the correlated alloy\nproperties across a vast compositional space. In the present work, we performed\nfirst-principles calculations with the special quasi-random structure (SQS)\nmethod to predict the unstable stacking fault energy ($\\gamma_{usf}$) of the\n$(1\\bar10)[111]$ slip system and the $(1\\bar10)$-plane surface energy\n($\\gamma_{surf}$) for 106 individual binary, ternary and quaternary bcc\nsolid-solution alloys with constituent elements among Ti, Zr, Hf, V, Nb, Ta,\nMo, W, Re and Ru. Moreover, with the first-principles data and a set of\nphysics-informed descriptors, we developed surrogate models based on\nstatistical regression to accurately and efficiently predict $\\gamma_{usf}$ and\n$\\gamma_{surf}$ for refractory multicomponent alloys in the 10-element\ncompositional space. Building upon binary and ternary data, the surrogate\nmodels show outstanding predictive ability in the high-order multicomponent\nsystems. The ratio between $\\gamma_{surf}$ and $\\gamma_{usf}$ is a parameter to\nreflect the potency of intrinsic ductility of an alloy based on the Rice model\nof crack-tip deformation. Therefore, using the surrogate models, we performed a\nsystematic screening of $\\gamma_{usf}$, $\\gamma_{surf}$ and their ratio over\n112,378 alloy compositions to search for alloy candidates that may have\nenhanced strength-ductile synergies. Search results were also confirmed by\nadditional first-principles calculations."
    },
    {
        "anchor": "Temperature-dependent proximity magnetism in Pt: We experimentally demonstrate the existence of magnetic coupling between two\nferromagnets separated by a thin Pt layer. The coupling remains ferromagnetic\nregardless of the Pt thickness, and exhibits a significant dependence on\ntemperature. Therefore, it cannot be explained by the established mechanisms of\nmagnetic coupling across nonmagnetic spacers. We show that the experimental\nresults are consistent with the presence of magnetism induced in Pt in\nproximity to ferromagnets, in direct analogy to the well-known proximity\neffects in superconductivity.",
        "positive": "Giant anomalous Nernst effect and quantum-critical scaling in a\n  ferromagnetic semimetal: In metallic ferromagnets, the Berry curvature of underlying quasiparticles\ncan cause an electric voltage perpendicular to both magnetization and an\napplied temperature gradient, a phenomenon called the anomalous Nernst effect\n(ANE). Here, we report the observation of a giant ANE in the full-Heusler\nferromagnet Co$_2$MnGa, reaching $S_{yx}\\sim -6$ $\\mu$V/K at room $T$, one\norder of magnitude larger than the maximum value reported for a magnetic\nconductor. With increasing temperature, the transverse thermoelectric\nconductivity or Peltier coefficient $\\alpha_{yx}$ shows a crossover between\n$T$-linear and $-T \\log(T)$ behaviors, indicating the violation of Mott formula\nat high temperatures. Our numerical and analytical calculations indicate that\nthe proximity to a quantum Lifshitz transition between type-I and type-II\nmagnetic Weyl fermions is responsible for the observed crossover properties and\nan enhanced $\\alpha_{yx}$. The $T$ dependence of $\\alpha_{yx}$ in experiments\nand numerical calculations can be understood in terms of a quantum critical\nscaling function predicted by the low energy effective theory over more than a\ndecade of temperatures. Moreover, the observation of chiral anomaly or an\nunsaturated positive longitudinal magnetoconductance also provide evidence for\nthe existence of Weyl fermions in Co$_2$MnGa."
    },
    {
        "anchor": "Entropy driven atomic motion in laser-excited bismuth: We introduce a thermodynamical model based on the two-temperature approach in\norder to fully understand the dynamics of the coherent A$_{1g}$ phonon in\nlaser-excited bismuth. Using this model, we simulate the time evolution of\n(111) Bragg peak intensities measured by Fritz {\\it{et al}} [Science {\\bf 315},\n633 (2007)] in femtosecond X-ray diffraction experiments performed on a bismuth\nfilm for different laser fluences. The agreement between theoretical and\nexperimental results is striking not only because we use fluences very close to\nthe experimental ones but also because most of the model parameters are\nobtained from {\\it{ab-initio}} calculations performed for different electron\ntemperatures.",
        "positive": "Locality of correlation in density functional theory: The Hohenberg-Kohn density functional was long ago shown to reduce to the\nThomas-Fermi approximation in the non-relativistic semiclassical (or large-$Z$)\nlimit for all matter, i.e, the kinetic energy becomes local. Exchange also\nbecomes local in this limit. Numerical data on the correlation energy of atoms\nsupports the conjecture that this is also true for correlation, but much less\nrelevant to atoms. We illustrate how expansions around large particle number\nare equivalent to local density approximations and their strong relevance to\ndensity functional approximations. Analyzing highly accurate atomic correlation\nenergies, we show that the correlation energy tends to $-A_c Z ln Z + B_c Z$ as\n$Z$ tends to infinity, where $Z$ is the atomic number, $A_c$ is known, and we\nestimate $B_c$ to be about 37 millihartrees. The local density approximation\nyields $A_c$ exactly, but a very incorrect value for $B_c$, showing that the\nlocal approximation is less relevant for correlation alone. This limit is a\nbenchmark for the non-empirical construction of density functional\napproximations. We conjecture that, beyond atoms, the leading correction to the\nlocal density approximation in the large-$Z$ limit generally takes this form,\nbut with $B_c$ a functional of the TF density for the system. The implications\nfor construction of approximate density functionals are discussed."
    },
    {
        "anchor": "Magnetic-domain-dependent pseudogap induced by Fermi surface nesting in\n  a centrosymmetric skyrmion magnet: Skyrmions in non-centrosymmetric materials are believed to occur due to the\nDzyaloshinskii-Moriya interaction. In contrast, the skyrmion formation\nmechanism in centrosymmetric materials remains elusive. Among those, Gd-based\ncompounds are the prototype compounds; however, their electronic structure is\nnot uncovered, even though it should be the foundation for elucidating the\nskyrmion mechanism. Here, we reveal the intrinsic electronic structure of\nGdRu2Si2 for the first time by magnetic domain selective measurements of\nangle-resolved photoemission spectroscopy (ARPES). In particular, we find the\nrobust Fermi surface (FS) nesting, consistent with the q-vector detected by the\nprevious resonant X-ray scattering (RXS) measurements. Most importantly, we\nfind that the pseudogap is opened at the nested portions of FS at low\ntemperatures. The momentum locations of the pseudogap vary for different\nmagnetic domains, most likely having a direct relationship with the screw-type\nspin modulation that changes direction for each domain. Intriguingly, the\nanomalous pseudogap disconnects the FS to generate Fermi arcs with 2-fold\nsymmetry. These results indicate the significance of\nRuderman-Kittel-Kasuya-Yosida (RKKY) interaction, in which itinerant electrons\nmediate to stabilize the local magnetic moment, as the mechanism for the\nmagnetism in the Gd-based skyrmion magnets. Our data also predict that the\nmomentum space where the pseudogap opens is doubled (or Fermi arcs shrink) and\nthereby stabilizes the skyrmion phase under a magnetic field. Furthermore, we\ndemonstrate the flexible nature of magnetism in GdRu2Si2 by manipulating\nmagnetic domains with a magnetic field and temperature cyclings, providing a\npossibility of future application for data storage and processing device with\ncentrosymmetric skyrmion magnets.",
        "positive": "p x n-Type Transverse Thermoelectrics in a Type-II Weyl Semimetal\n  TaIrTe4: p x n-type materials refer to materials with a p-type Seebeck coefficient in\none direction and a n-type coefficient in the orthogonal direction. This type\nof materials allows for a transverse thermoelectric response, which is highly\ndesirable for energy applications. Here, we report the observation of p x\nn-type behavior in TaIrTe4, a type-II Weyl semimetal, with an in-plane\nthermopower anisotropy S$_{xx}$-S$_{yy}$ reaches a maximum value 40${\\mu}$V/K\nat 200K. Intriguingly. we found that such a p x n-type behavior is absent in\nthe similar compound NbIrTe4. The presence and absence of p x n-type behavior\nin these two materials are consistent with density functional theory\ncalculations, which further predict that the thermopower anisotropy in both\ncompounds can be enhanced up to 130${\\mu}$V/K by electron doping. Such a strong\nthermopower anisotropy originates from the presence of both p-type and n-type\ncarriers, each with high mobility in one direction. These results suggest that\nalthough type-II Weyl semimetal phase does not guarantee the existence of p x\nn-type behavior, its unique band structure provides the ingredient to engineer\nand optimize this phenomenon."
    },
    {
        "anchor": "Evolution of perpendicular magnetized tunnel junctions upon annealing: We study the evolution of perpendicularly magnetized tunnel junctions under\n300 to 400 $^{\\circ}$C annealing. The hysteresis loops do not evolve much\nduring annealing and they are not informative of the underlying structural\nevolutions. These evolutions are better revealed by the frequencies of the\nferromagnetic resonance eigenmodes of the tunnel junction. Their modeling\nprovides the exchange couplings and the layers' anisotropies within the stack\nwhich can serve as a diagnosis of the tunnel junction state after each\nannealing step. The anisotropies of the two CoFeB-based parts and the two\nCo/Pt-based parts of the tunnel junction decay at different rates during\nannealing. The ferromagnet exchange coupling through the texture-breaking Ta\nlayer fails above 375$^{\\circ}$C. The Ru spacer meant to promote a synthetic\nantiferromagnet behavior is also insufficiently robust to annealing. Based on\nthese evolutions we propose optimization routes for the next generation tunnel\njunctions.",
        "positive": "Incoherent population mixing contributions to phase-modulation\n  two-dimensional coherent excitation spectra: We present theoretical and experimental results showing the effects of\nincoherent population mixing on two-dimensional (2D) coherent excitation\nspectra that are measured via a time-integrated population and phase-sensitive\ndetection. The technique uses four collinear ultrashort pulses and phase\nmodulation to acquire two-dimensional spectra by isolating specific nonlinear\ncontributions to the photoluminescence or photocurrent excitation signal. We\ndemonstrate that an incoherent contribution to the measured lineshape, arising\nfrom nonlinear population dynamics over the entire photoexcitation lifetime,\ngenerates a similar lineshape to the expected 2D coherent spectra in\ncondensed-phase systems. In those systems, photoexcitations are mobile such\nthat inter-particle interactions are important on any timescale, including\nthose long compared to the 2D coherent experiment. Measurements on a\nsemicrystalline polymeric semiconductor film at low temperature show that, in\nsome conditions in which multi-exciton interactions are suppressed, the\ntechnique predominantly detects coherent signal and can be used, in our\nexample, to extract homogeneous linewidths. The same method used on a\nlead-halide perovskite photovoltaic cell shows that incoherent population\nmixing of mobile photocarriers can dominate the measured signal since\ncarrier-carrier bimolecular scattering is active even at low excitation\ndensities, which hides the coherent contribution to the spectral lineshape."
    },
    {
        "anchor": "Universal correction for the Becke-Johnson exchange potential: The Becke-Johnson exchange potential [J. Chem. Phys. 124, 221101 (2006)] has\nbeen successfully used in electronic structure calculations within\ndensity-functional theory. However, in its original form the potential may\ndramatically fail in systems with non-Coulombic external potentials, or in the\npresence of external magnetic or electric fields. Here, we provide a\nsystem-independent correction to the Becke-Johnson approximation by (i)\nenforcing its gauge invariance and (ii) making it exact for any single-electron\nsystem. The resulting approximation is then better designed to deal with\ncurrent-carrying states, and recovers the correct asymptotic behavior for\nsystems with any number of electrons. Tests of the resulting corrected exchange\npotential show very good results for a Hydrogen chain in an electric field and\nfor a four-electron harmonium in a magnetic field.",
        "positive": "Dynamics and Scaling of One Dimensional Surface Structures: We study several one dimensional step flow models. Numerical simulations show\nthat the slope of the profile exhibits scaling in all cases. We apply a scaling\nansatz to the various step flow models and investigate their long time\nevolution. This evolution is described in terms of a continuous step density\nfunction, which scales in time according to D(x,t)=F(xt^{-1/\\gamma}). The value\nof the scaling exponent \\gamma depends on the mass transport mechanism. When\nsteps exchange atoms with a global reservoir the value of \\gamma is 2. On the\nother hand, when the steps can only exchange atoms with neighboring terraces,\n\\gamma=4. We compute the step density scaling function for three different\nprofiles for both global and local exchange mechanisms. The computed density\nfunctions coincide with simulations of the discrete systems. These results are\ncompared to those given by the continuum approach of Mullins."
    },
    {
        "anchor": "Formation and Growth of Nanowire: The kinetics of main physical processes controlling the growth of nanowires\n(NW) via evolution pass \" vapor-liquid-solid\" is considered. The roles of the\nthermodynamics and kinetics of cluster nucleation in the initial stage of NW\nformation are studied. Approximate expressions for NW length are obtained in\none-dimensional approximation. The influence of transfer processes in the gas\nphase on the growth NW is evaluated. The effect of release of the latent heat\nof phase transition and heat conduction along NW is considered. For carbon NW,\ngrown on Ni catalytic particles, numerical results are obtained. PACS: 64.70Dv,\n68.70+w.",
        "positive": "Experimental evidence of giant chiral magnetic effect in type-II Weyl\n  semimetal WP$_{2+\u03b4}$ crystals: Chiral magnetic effect is a quantum phenomenon that is breaking of chiral\nsymmetry of relativistic Weyl fermions by quantum fluctuation under paralleled\nelectric field E and magnetic field B. Intuitively, Weyl fermions with\ndifferent chirality, under stimulus of paralleled E and B, will have different\nchemical potential that gives rise to an extra current, whose role likes a\nchiral battery in solids. However, up to now, the experimental evidence for\nchiral magnetic effect is the negative longitudinal magnetoresistance rather\nthan a chiral electric source. Here, totally different from previous reports,\nwe observed the giant chiral magnetic effect evidenced by: 'negative'\nresistivity and corresponding voltage-current curves lying the second-fourth\nquadrant in type-II Weyl semimetal WP$_{2+\\delta}$ under following conditions:\nthe misaligned angle between E and B is smaller than 20$^\\circ$, temperature\n<30 K and externally applied E<50 mA. Phenomenologically, based on macroscopic\nChern-Simon-Maxwell equation, the giant chiral magnetic effect observed in\nWP$_{2+\\delta}$ is attributed to two-order higher coherent time of chiral\nWeyl-fermion quantum state over Drude transport relaxation-time. This work\ndemonstrates the giant chiral-magnetic/chiral-battery effect in Weyl\nsemimetals."
    },
    {
        "anchor": "Distinct magnetotransport and orbital fingerprints of chiral bobbers: While chiral magnetic skyrmions have been attracting significant attention in\nthe past years, recently, a new type of a chiral particle emerging in thin\nfilms $-$ a chiral bobber $-$ has been theoretically predicted and\nexperimentally observed. Here, based on theoretical arguments, we provide a\nclear pathway to utilizing chiral bobbers for the purposes of future\nspintronics by uncovering that these novel chiral states possess inherent\ntransport fingerprints that allow for their unambiguous electrical detection in\nsystems comprising several types of chiral states. We reveal that unique\ntransport and orbital characteristics of bobbers root in the non-trivial\nmagnetization distribution in the vicinity of the Bloch points, and demonstrate\nthat tuning the details of the Bloch point topology can be used to drastically\nalter the emergent response properties of chiral bobbers to external fields,\nwhich bears great potential for engineering chiral dynamics and cognitive\ncomputing.",
        "positive": "Temperature Dependence of Spin Hall Angle of Palladium: In this study, the temperature dependence of the spin Hall angle of palladium\n(Pd) was experimentally investigated by spin pumping. A Ni80Fe20/Pd bilayer\nthin film was prepared, and a pure spin current was dynamically injected into\nthe Pd layer. This caused the conversion of the spin current to a charge\ncurrent owing to the inverse spin Hall effect. It was found that the spin Hall\nangle varies as a function of temperature, whereby the value of the spin Hall\nangle increases to ca. 0.02 at 123 K."
    },
    {
        "anchor": "Atomic topology and radial distribution functions of a-SiNx: We report a new approach to simulate amorphous networks of covalently bonded\nmaterials that leads to excellent radial distribution functions and realistic\natomic arrangements. We apply it to generate the first ab initio structures of\nnitrogen-doped silicon, a-SiNx, for thirteen values of x from 0 to the nearly\nstoichiometric composition of x=1.29, using the Harris functional and thermally\namorphizised, periodically continued, diamond-like cells with 64 atoms. Partial\nradial features are reported for the first time and the total radial\ndistribution functions agree very well with the few existing experiments. Our\nresults should stimulate further experimental and theoretical studies in\namorphous covalent materials.",
        "positive": "Epitaxial graphene prepared by chemical vapor deposition on single\n  crystal thin iridium films on sapphire: Uniform single layer graphene was grown on single-crystal Ir films a few\nnanometers thick which were prepared by pulsed laser deposition on sapphire\nwafers. These graphene layers have a single crystallographic orientation and a\nvery low density of defects, as shown by diffraction, scanning tunnelling\nmicroscopy, and Raman spectroscopy. Their structural quality is as high as that\nof graphene produced on Ir bulk single crystals, i.e. much higher than on metal\nthin films used so far."
    },
    {
        "anchor": "The reversible lithiation of SnO: a three-phase process: A high reversible capacity is a key feature for any rechargeable battery. In\nthe lithium-ion battery technology, tin-oxide anodes do fulfill this\nrequirement, but a fast loss of capacity hinders a full commercialization.\nUsing first-principles calculations, we propose a microscopic model that sheds\nlight on the reversible lithiation/delithiation of SnO and reveals that a\nsintering of Sn causes a strong degradation of SnO-based anodes. When the\ninitial irreversible transformation ends, active anode grains consist of\nLi-oxide layers separated by Sn bilayers. During the following reversible\nlithiation, the Li-oxide undergoes two phase transformations that give rise to\na Li-enrichment of the oxide and the formation of a layered SnLi composite. We\nfind that the model-predicted anode volume expansion and voltage profile agree\nwell with experiment, and a layered anode grain is highly-conductive and has a\ntheoretical reversible capacity of 4.5 Li atoms per a SnO host unit. The model\nsuggests that the grain structure has to remain layered to sustain its\nreversible capacity and a thin-film design of battery anodes could be a remedy\nfor the capacity loss.",
        "positive": "Eutectic colony formation in systems with interfacial energy anisotropy:\n  A phase field study: Instability of a binary eutectic solidification front to morphological\nperturbations due to rejection of a ternary impurity leads to the formation of\neutectic colonies. Whereas, the instability dynamics and the resultant mi-\ncrostructural features are reasonably well understood for isotropic systems,\nseveral experimental observations point to the existence of colonies in systems\nwith anisotropic interfaces. In this study, we extend the un- derstanding of\neutectic colonies to anisotropic systems, where only certain orientations of\nthe solid-liquid or solid-solid interfaces are thermodynamically stable.\nThrough phase field simulations in 2D and 3D, we have systematically probed the\ncolony formation dynamics and the resulting microstructures, as functions of\nthe pulling velocity and the relative orientation of the equilibrium interfaces\nwith that of the imposed tempera- ture gradient. We find that in 2D, stabler\nfinger spacings are selected with an increase in the magnitude of anisotropy\nintroduced, either in the solid-liquid or in the solid-solid interface. The\nfingers have a well-defined orientation for the case of anisotropy in the\nsolid-liquid interface, with no fixed orientations for the lamellae\nconstituting the colony. For the case where anisotropy exists in the\nsolid-solid interface, the lamellae tend to orient themselves along the\ndirection of the imposed temperature gradient, with tilted solid-liquid\ninterfaces from the horizontal. The 3D simulations reveal existence of eutectic\nspirals which might become tilted under certain orientations of the equilibrium\ninterfaces. Our simulations are able to explain several key features observed\nin our experimantal studies of solidification in Ni-Al-Zr alloy."
    },
    {
        "anchor": "High performance magnetic material with Ce and La: an alternative to\n  Nd-Fe-B magnet: A systematic study of magnetocrystalline anisotropy is performed for\nR(La/Ce/Nd)2Fe14B tetragonal compound with the site substitution mechanism.\nTheoretical calculation suggests the 50% doping with Ce at 4f-site can lead to\ncompetitive magnetic anisotropy to that of the champion magnet Nd2Fe14B.\nElectronic structure calculations are performed using the full-potential\nlinearized augmented plane wave method by inclusion of the spin-orbit coupling\nand Hubbard (U) interaction in the calculation for the rare-earth elements to\nget the correct influence of the localized 4f orbitals. Detailed analysis of\nthe magnetic moment and magnetic anisotropy change has been studied by\nindividually inserting the La and Ce atoms at the two inequivalent sites (4g\nand 4f sites) of the 2-14-B tetragonal structure. Accurate prediction of the\ntotal magnetic moment with the orbital contribution in the 2-14-B structure\nshows the maximum moment for Ce2Fe14B (3.86 {\\mu}B/f.u less) compared to\nNd2Fe14B. Theoretical analysis confirms that regardless of the anti-parallel\nspin moment emerging in the Ce atom the complex structure of the Ce substituted\ncompound at 4f-site gives the maximum anisotropy of 2.27 meV/cell with lowering\nthe magnetic moment by 1.26 {\\mu}B/f.u. compared to the Nd2Fe14B compound.",
        "positive": "Structural stability versus conformational sampling in biomolecular\n  systems: Why is the charge transfer efficiency in G4-DNA better than in\n  double-stranded DNA?: The electrical conduction properties of G4-DNA are investigated using a\nhybrid approach, which combines electronic structure calculations, molecular\ndynamics (MD) simulations, and the formulation of an effective tight-binding\nmodel Hamiltonian. Charge transport is studied by computing transmission\nfunctions along the MD trajectories. Though G4-DNA is structurally more stable\nthan double-stranded DNA (dsDNA), our results strongly suggest that the\npotential improvement of the electrical transport properties in the former is\nnot necessarily related to an increased stability, but rather to the fact that\nG4 is able to explore in its conformational space a larger number of\ncharge-transfer active conformations. This in turn is a result of the\nnon-negligible interstrand matrix elements, which allow for additional charge\ntransport pathways. The higher structural stability of G4 can however play an\nimportant role once the molecules are contacted by electrodes. In this case, G4\nmay experience weaker structural distortions than dsDNA and thus preserve to a\nhigher degree its conduction properties."
    },
    {
        "anchor": "Theoretical Prediction of the Robust Intrinsic Half-Metallicity in Ni2N\n  MXene with Different Types of Surface Terminations: Bare and surface-passivated Fe2N, Co2N, and Ni2N MXene were investigated by\nusing density functional theory. Fe2N(OH)2, Fe2NO2, Co2NO2, Ni2NF2, Ni2N(OH)2,\nand Ni2NO2 are intrinsic half-metals, while other structures have\nantiferromagnetic ground states. The half-metallicity of Ni2NT2 (T = F, OH, and\nO) does not depend on the type of surface terminations and should be more\nrealizable in experiments. The energy differences between the ferromagnetic and\nantiferromagnetic configurations of Ni2NT2 are several hundreds of meV per\nprimitive cell. The Curie temperature should be above room temperature from the\npoint of view of mean field approximation.",
        "positive": "Radiative Lifetime of Excitons in Carbon Nanotubes: We calculate the radiative lifetime and energy bandstructure of excitons in\nsemiconducting carbon nanotubes, within a tight-binding approach. In the limit\nof rapid interband thermalization, the radiative decay rate is maximized at\nintermediate temperatures, decreasing at low temperature because the\nlowest-energy excitons are optically forbidden. The intrinsic phonons cannot\nscatter excitons between optically active and forbidden bands, so\nsample-dependent extrinsic effects that break the symmetries can play a central\nrole. We calculate the diameter-dependent energy splittings between singlet and\ntriplet excitons of different symmetries, and the resulting dependence of\nradiative lifetime on temperature and tube diameter."
    },
    {
        "anchor": "Electronic structure of nanoscale iron oxide particles measured by\n  scanning tunneling and photoelectron spectroscopies: We have investigated the electronic structure of nano-sized iron oxide by\nscanning tunnelling microscopy (STM) and spectroscopy (STS) as well as by\nphotoelectron spectroscopy. Nano particles were produced by thermal treatment\nof Ferritin molecules containing a self-assembled core of iron oxide. Depending\non the thermal treatment we were able to prepare different phases of iron oxide\nnanoparticles resembling gamma-Fe2O3, alpha-Fe2O3, and a phase which apparently\ncontains both gamma-Fe2O3 and alpha-Fe2O3. Changes to the electronic structure\nof these materials were studied under reducing conditions. We show that the\nsurface band gap of the electronic excitation spectrum can differ from that of\nbulk material and is dominated by surface effects.",
        "positive": "Temperature dependent Neel wall dynamics in GaMnAs/GaAs: Extensive Kerr microscopy studies reveal a strongly temperature dependent\ndomain wall dynamics in Hall-bars made from compressively strained GaMnAs.\nDepending on the temperature magnetic charging of domain walls is observed and\nnucleation rates depend on the Hall-geometry with respect to the crystal axes.\nAbove a critical temperature where a biaxial-to-uniaxial anisotropy transition\noccurs a drastic increase of nucleation events is observed. Below this\ntemperature, the nucleation of domains tends to be rather insensitive to\ntemperature. This first spatially resolved study of domain wall dynamics in\npatterned GaMnAs at variable temperatures has important implications for\npotential single domain magneto-logic devices made from ferromagnetic\nsemiconductors."
    },
    {
        "anchor": "Applicability of the strongly constrained and appropriately normed\n  density functional to transition metal magnetism: We find that the recently developed self consistent and appropriately normed\n(SCAN) meta-generalized gradient approximation, which has been found to provide\nhighly accurate results for many materials, is, however, not able to describe\nthe stability and properties of phases of Fe important for steel. This is due\nto an overestimated tendency towards magnetism and exaggeration of magnetic\nenergies, which we also find in other transition metals.",
        "positive": "Network analysis of the performance of organic photovoltaic cells: The\n  open circuit voltage and the zero current efficiency: Photovoltaic energy conversion in photovoltaic cells has been analyzed by the\ndetailed balance approach or by thermodynamic arguments. Here we introduce a\nnetwork representation to analyze the performance of such systems once a\nsuitable kinetic model (represented by a master equation in the space of the\ndifferent system states) has been constructed. Such network representation\nallows one to decompose the steady state dynamics into cycles, characterized by\ntheir cycle affinities. The maximum achievable efficiency of the device is\nobtained in the zero affinity limit. This method is applied to analyze a\nmicroscopic model for a bulk heterojunction organic solar cell that includes\nthe essential optical and interfacial electronic processes that characterize\nthis system, leading to an explicit expression for the theoretical efficiency\nlimit in such system. In particular, the deviation from Carnot's efficiency\nassociated with the exciton binding energy is quantified."
    },
    {
        "anchor": "Accelerating quantum materials development with advances in transmission\n  electron microscopy: Quantum materials are driving a technology revolution in sensing,\ncommunication, and computing, while simultaneously testing many core theories\nof the past century. Materials such as topological insulators, complex oxides,\nquantum dots, color center hosting semiconductors, and other types of strongly\ncorrelated materials can exhibit exotic properties such as edge conductivity,\nmultiferroicity, magnetoresistance, single photon emission, and optical-spin\nlocking. These emergent properties arise and depend strongly on the materials\ndetailed atomic scale structure, including atomic defects, dopants, and lattice\nstacking. In this review, after introduction of different classes of quantum\nmaterials and quantum excitations, we describe how progress in the field of\nelectron microscopy, including in situ and in operando EM, can accelerate\nadvances in quantum materials. Our review describes EM methods including: i)\nprinciples and operation modes of EM, ii) EM spectroscopies, such as electron\nenergy loss spectroscopy, cathodoluminescence, and electron energy gain\nspectroscopy, iii) 4D scanning transmission electron microscopy, iv) dynamic\nand ultrafast EM, v) complimentary ultrafast spectroscopies, and vi) atomic\nelectron tomography. We discuss how these methods inform structure function\nrelations in quantum materials down to the picometer scale and femtosecond time\nresolution, and how they enable high resolution manipulation of quantum\nmaterials. Among numerous results, our review highlights how EM has enabled\nidentification of the 3D structure of quantum defects, measuring reversible and\nmetastable dynamics of quantum excitations, mapping exciton states and single\nphoton emission, measuring nanoscale thermal transport and coupled excitation\ndynamics, and measuring the internal electric field of quantum\nheterointerfaces, all at the quantum materials intrinsic atomic and near\natomic-length scale.",
        "positive": "Diamagnetic Effects, Spin Dependent Fermi Surfaces, and the Giant\n  Magnetoresistance in Metallic Multilayers: We study the role of diamagnetic effects on the transport properties of\nmetallic magnetic multilayers to elucidate whether they can explain the Giant\nMagnetoresistance (GMR) effect observed in those systems. Realistic Fermi\nsurface topologies in layered ferromagnets are taken into account, with the\npossibilities of different types of orbits depending on the electron spin. Both\nconfigurations, with ferromagnetic and anti-ferromagnetic couplings between\nmagnetic layers, are considered and the transmission coefficient for scattering\nat the interface boundary is modelled to include magnetic and roughness\ncontributions. We assume that scattering processes conserve the electron spin,\ndue to large spin diffusion lengths in multilayer samples. Scattering from the\nspacer mixes different orbit topologies in a way similar to magnetic\n`breakdown' phenomena. For antiferromagnetic coupling, majority and minority\nspins are interchanged from one magnetic layer to the next. Cyclotron orbits\nare also traveled in opposite directions, producing a compensation-like effect\nthat yields a huge GMR, particularly for closed orbits. For open orbits, one\nmay get the `inverse' magnetoresistance effect along particular directions."
    },
    {
        "anchor": "From colossal to zero: Controlling the Anomalous Hall Effect in Magnetic\n  Heusler Compounds via Berry Curvature Design: Since the discovery of the anomalous Hall effect (AHE), the anomalous Hall\nconductivity (AHC) has been thought to be zero when there is no net\nmagnetization. However, the recently found relation between the intrinsic AHE\nand the Berry curvature predicts other possibilities, such as a large AHC in\nnon-colinear antiferromagnets with no net magnetization but net Berry\ncurvature. Vice versa, the AHE in principle could be tuned to zero,\nirrespective of a finite magnetization. Here, we experimentally investigate\nthis possibility and demonstrate that, the symmetry elements of Heusler magnets\ncan be changed such that the Berry curvature and all the associated properties\nare switched while leaving the magnetization unaffected. This enables us to\ntune the AHC from 0 {\\Omega}-1cm-1 up to 1600 {\\Omega}-1cm-1 with an\nexceptionally high anomalous Hall angle up to 12 %, while keeping the\nmagnetization same. Our study shows that the AHC can be controlled by\nselectively changing the Berry curvature distribution, independent of the\nmagnetization.",
        "positive": "A First-Principles Approach to Insulators in Finite Electric Fields: We describe a method for computing the response of an insulator to a static,\nhomogeneous electric field. It consists of iteratively minimizing an electric\nenthalpy functional expressed in terms of occupied Bloch-like states on a\nuniform grid of k points. The functional has equivalent local minima below a\ncritical field E_c that depends inversely on the density of k points; the\ndisappearance of the minima at E_c signals the onset of Zener breakdown. We\nillustrate the procedure by computing the piezoelectric and nonlinear\ndielectric susceptibility tensors of III-V semiconductors."
    },
    {
        "anchor": "Comparison of Graphene Formation on C-face and Si-face SiC {0001}\n  Surfaces: The morphology of graphene formed on the (000-1) surface (the C-face) and the\n(0001) surface (the Si-face) of SiC, by annealing in ultra-high vacuum or in an\nargon environment, is studied by atomic force microscopy and low-energy\nelectron microscopy. The graphene forms due to preferential sublimation of Si\nfrom the surface. In vacuum, this sublimation occurs much more rapidly for the\nC-face than the Si-face, so that 150 C lower annealing temperatures are\nrequired for the C-face to obtain films of comparable thickness. The evolution\nof the morphology as a function of graphene thickness is examined, revealing\nsignificant differences between the C-face and the Si-face. For annealing near\n1320 C, graphene films of about 2 monolayers (ML) thickness are formed on the\nSi-face, but 16 ML is found for the C-face. In both cases, step bunches are\nformed on the surface. For the Si-face, layer-by-layer growth of the graphene\nis observed in areas between the step bunches. At 1170 C, for the C-face, a\nmore 3-dimensional type of growth is found. The average thickness is then about\n4 ML, but with a wide variation in local thickness (2 - 7 ML) over the surface.\nThe spatial arrangement of constant-thickness domains are found to be\ncorrelated with step bunches on the surface, which form in a more restricted\nmanner than at 1320 C. It is argued that these domains are somewhat\ndisconnected, so that no strong driving force for planarization of the film\nexists. In a 1-atm argon environment, permitting higher growth temperatures,\nthe graphene morphology for the Si-face is found to become more\nlayer-by-layer-like even for graphene thickness as low as 1 ML. However, for\nthe C-face the morphology becomes much worse, with the surface displaying\nmarkedly inhomogeneous nucleation of the graphene. It is demonstrated that\nthese surfaces are unintentionally oxidized, which accounts for the\ninhomogeneous growth.",
        "positive": "High Permittivity Dielectric Field-Plated Vertical (001)\n  $\u03b2$-Ga$_2$O$_3$ Schottky Barrier Diode with Surface Breakdown Electric\n  Field of 5.45 MV/cm and BFOM of $>$ 1 GW/cm$^{2}$: This paper presents vertical (001) oriented $\\beta$-Ga$_2$O$_3$ field plated\n(FP) Schottky barrier diode (SBD) with a novel extreme permittivity dielectric\nfield oxide. A thin drift layer of 1.7 $\\mu m$ was used to enable a\npunch-through (PT) field profile and very low differential specific\non-resistance (R$_{on-sp}$) of 0.32 m$\\Omega$-cm$^{2}$. The extreme\npermittivity field plate oxide facilitated the lateral spread of the electric\nfield profile beyond the field plate edge and enabled a breakdown voltage\n($V_{br}$) of 687 V. The edge termination efficiency increases from 13.5 $\\%$\nfor non-field plated structure to 63 $\\%$ for high permittivity field plate\nstructure. The surface breakdown electric field was extracted to be 5.45 MV/cm\nat the center of the anode region using TCAD simulations. The high permittivity\nfield plated SBD demonstrated a record high Baliga figure of merit (BFOM) of\n1.47 GW/cm$^{2}$ showing the potential of Ga$_2$O$_3$ power devices for\nmulti-kilovolt class applications."
    },
    {
        "anchor": "Magneto-optic Faraday effect in maghemite nanoparticles/silica matrix\n  nanocomposites prepared by the Sol-Gel method: Bulk monolithic samples of {\\gamma}-Fe2O3/SiO2 composites with different iron\noxide/silica ratios have been prepared by the sol-gel technique. Iron oxide\nnanoparticles are obtained in-situ during heat treatment of samples and silica\nmatrix consolidation. Preparation method was previously optimized to minimize\nthe percentage of antiferromagnetic {\\alpha}-Fe2O3 and parallelepipeds of\nroughly 2x5x12 mm3, with good mechanical stability, are obtained. RT\nmagnetization curves show a non-hysteretic behavior. Thus, magnetization\nmeasurements have been well fitted to an expression that combines the Langevin\nequation with an additional linear term, indicating that some of the\nnanoparticles are still superparamagnetic as confirmed by X-ray diffraction and\nelectron microscopy measurements. Zero field cooled /field cooled experiments\nshow curves with slightly different shapes, depending on the size and shape\ndistribution of nanoparticles for a given composition. Magneto-optical Faraday\neffect measurements show that the Faraday rotation is proportional to\nmagnetization of the samples, as expected. As a demonstration of their sensing\npossibilities, the relative intensity of polarized light, measured at 5{\\deg}\nfrom the extinction angle, was plotted versus applied magnetic field.",
        "positive": "Dopant-Dopant Interactions in Beryllium doped Indium Gallium Arsenide:\n  an Ab Initio Study: We present an ab initio study of dopant-dopant interactions in\nberyllium-doped InGaAs. We consider defect formation energies of various\ninterstitial and substitutional defects and their combinations. We find that\nall substitutional-substitutional interactions can be neglected. On the other\nhand, interactions involving an interstitial defect are significant. Specially,\ninterstitial Be is stabilized by about 0.9/1.0 eV in the presence of one/two\nBeGa substitutionals. Ga interstitial is also substantially stabilized by Be\ninterstitials. Two Be interstitials can form a metastable Be-Be-Ga complex with\na dissociation energy of 0.26 eV/Be. Therefore, interstitial defects and\ndefect-defect interactions should be considered in accurate models of Be doped\nInGaAs. We suggest that In and Ga should be treated as separate atoms and not\nlumped into a single effective group III element, as has been done before. We\nidentified dopant-centred states which indicate the presence of other charge\nstates at finite temperatures, specifically, the presence of Beint+1 (as\nopposed to Beint+2 at 0K)."
    },
    {
        "anchor": "Full Electroresistance Modulation in a Mixed-Phase Metallic Alloy: We report a giant, ~22%, electroresistance modulation for a metallic alloy\nabove room temperature. It is achieved by a small electric field of 2 kV/cm via\npiezoelectric strain-mediated magnetoelectric coupling and the resulting\nmagnetic phase transition in epitaxial FeRh/BaTiO3 heterostructures. This work\npresents detailed experimental evidence for an isothermal magnetic phase\ntransition driven by tetragonality modulation in FeRh thin films, which is in\ncontrast to the large volume expansion in the conventional temperature-driven\nmagnetic phase transition in FeRh. Moreover, all the experimental results in\nthis work illustrate FeRh as a mixed-phase model system well similar to\nphase-separated colossal magnetoresistance systems with phase instability\ntherein.",
        "positive": "Disentangling the Evolution of Electrons and Holes in photoexcited ZnO\n  nanoparticles: The evolution of charge carriers in photoexcited room temperature ZnO\nnanoparticles in solution is investigated using ultrafast ultraviolet\nphotoluminescence spectroscopy, ultrafast Zn K-edge absorption spectroscopy and\nab-initio molecular dynamics (MD) simulations. The photoluminescence is excited\nat 4.66 eV, well above the band edge, and shows that electron cooling in the\nconduction band and exciton formation occur in <500 fs, in excellent agreement\nwith theoretical predictions. The X-ray absorption measurements, obtained upon\nexcitation close to the band edge at 3.49 eV, are sensitive to the migration\nand trapping of holes. They reveal that the 2 ps transient largely reproduces\nthe previously reported transient obtained at 100 ps time delay in synchrotron\nstudies. In addition, the X-ray absorption signal is found to rise in ~1.4 ps,\nwhich we attribute to the diffusion of holes through the lattice prior to their\ntrapping at singly-charged oxygen vacancies. Indeed, the MD simulations show\nthat impulsive trapping of holes induces an ultrafast expansion of the cage of\nZn atoms in <200 fs, followed by an oscillatory response at a frequency of ~100\ncm-1, which corresponds to a phonon mode of the system involving the Zn\nsub-lattice."
    },
    {
        "anchor": "Pressure dependence of structural, elastic, electronic, thermodynamic,\n  and optical properties of van der Waals-type NaSn2P2 pnictide superconductor:\n  insights from DFT study: NaSn2P2 is a recently discovered superconducting system belonging to a\nparticular class of materials with van der Waals structure. There is enormous\ninterest in such compounds because of their intriguing electrical, optical,\nchemical, thermal, and superconducting state properties. We have studied the\npressure dependent structural, thermo-physical, electronic band structure, and\nsuperconducting state properties of this quasi-two dimensional system in\ndetails for the first time via ab initio technique. The optical The optical\nproperties are also investigated for different electric field polarizations for\nthe first time. The elastic anisotropy indices point towards high level of\nmechanical and bonding anisotropy in NaSn2P2 consistent with its highly layered\nstructure. The pressure dependent superconducting transition temperature, Tc,\nof NaSn2P2 is predicted to vary strongly with the pressure dependent variation\nof Debye temperature. The electronic energy dispersion curves reveal high level\nof direction dependence; the effective mass of charge carries are particularly\nhigh for the out-of-plane charge transport. The optical parameters compliment\nthe underlying electronic energy density of states features and are weakly\ndependent on the polarization of the incident electric field. The reflectivity\nof NaSn2P2 is very high in the visible region and remains quite high and\nnon-selective over an extended energy range in the ultraviolet region. The\nabsorption coefficient is also high in the mid-ultraviolet band. All these\noptical features render NaSn2P2 suitable for optoelectronic device\napplications.",
        "positive": "Visualization of electronic topology in ZrSiSe by scanning tunneling\n  microscopy: As emerging topological nodal-line semimetals, the family of ZrSiX (X = O, S,\nSe, Te) has attracted broad interests in condensed matter physics due to their\nfuture applications in spintonics. Here, we apply a scanning tunneling\nmicroscopy (STM) to study the structural symmetry and electronic topology of\nZrSiSe. The glide mirror symmetry is verified by quantifying the lattice\nstructure of the ZrSe bilayer based on bias selective topographies. The\nquasiparticle interference analysis is used to identify the band structure of\nZrSiSe. The nodal line is experimentally determined at $\\sim$ 250 meV above the\nFermi level. An extra surface state Dirac point at $\\sim$ 400 meV below the\nFermi level is also determined. Our STM measurement provides a direct\nexperimental evidence of the nodal-line state in the family of ZrSiX."
    },
    {
        "anchor": "On the feasibility of pentamode mechanical metamaterials: Conceptually, all conceivable three-dimensional mechanical materials can be\nbuilt from pentamode materials. Pentamodes also enable to implement\nthree-dimensional transformation acoustics - the analogue of transformation\noptics. However, pentamodes have not been realized experimentally to the best\nof our knowledge. Here, we investigate inasmuch the pentamode theoretical ideal\nsuggested by Milton and Cherkaev in 1995 can be approximated by a metamaterial\nwith current state-of-the-art lithography. Using numerical calculations\ncalibrated by our fabricated three-dimensional microstructures, we find that\nthe figure of merit, i.e., the ratio of bulk modulus to shear modulus, can\nrealistically be made as large as about 1,000.",
        "positive": "Current-induced magnetization switching in CoTb amorphous single layer: We demonstrate spin-orbit torque (SOT) switching of amorphous CoTb single\nlayer films with perpendicular magnetic anisotropy (PMA). The switching\nsustains even the film thickness is above 10 nm, where the critical switching\ncurrent density keeps almost constant. Without the need of overcoming the\nstrong interfacial Dzyaloshinskii-Moriya interaction caused by the heavy metal,\na quite low assistant field of ~20 Oe is sufficient to realize the fully\nswitching. The SOT effective field decreases and undergoes a sign change with\nthe decrease of the Tb-concentration, implying that a combination of the spin\nHall effect from both Co and Tb as well as an asymmetric spin current\nabsorption accounts for the SOT switching mechanism. Our findings would advance\nthe use of magnetic materials with bulk PMA for energy-efficient and\nthermal-stable non-volatile memories, and add a different dimension for\nunderstanding the ordering and asymmetry in amorphous thin films."
    },
    {
        "anchor": "Magnetic quasicrystals: What can we expect to see in their neutron\n  diffraction data?: The theory of magnetic symmetry in quasicrystals is used to characterize the\nnature of magnetic peaks, expected in elastic neutron diffraction experiments.\nIt is established that there is no symmetry-based argument which forbids the\nexistence of quasiperiodic long-range magnetic order. Suggestions are offered\nas to where one should look for the simplest kinds of antiferromagnetic\nquasicrystals.",
        "positive": "Cold neutron scattering study on diffuse and phonon excitations in the\n  relaxor PbMg(1/3)Nb(2/3)O3: Cold neutron scattering experiments have been performed to explore the\nenergy, temperature, and wave-vector dependence of the diffuse scattering and\nthe transverse acoustic (TA) phonons in the relaxor PbMg(1/3)Nb(2/3)O3. We have\nobserved a weak, but definitive, diffuse scattering cross section above the\nBurns temperature T_d ~ 600 K. This cross section, which is most likely caused\nby chemical short-range order, persists down to 100 K, and coexists with the\nmuch stronger diffuse scattering that is attributed to the polar nanoregions. A\nsystematic study of the TA phonon around (1, 1, 0) has also been carried out.\nThe phonon is well defined for small wave vectors q, but broadens markedly\naround q = (0.1, -0.1, 0)."
    },
    {
        "anchor": "Bond-breaking Induced Lifshitz Transition in Robust Dirac Semimetal\n  $\\mathbf{VAl_3}$: Topological electrons in semimetals are usually vulnerable to chemical doping\nand environment change, which restricts their potential application in future\nelectronic devices. In this paper we report that the type-II Dirac semimetal\n$\\mathbf{VAl_3}$ hosts exceptional, robust topological electrons which can\ntolerate extreme change of chemical composition. The Dirac electrons remain\nintact even after a substantial part of V atoms have been replaced in the\n$\\mathbf{V_{1-x}Ti_xAl_3}$ solid solutions. This Dirac semimetal state ends at\n$x=0.35$ where a Lifshitz transition to $p$-type trivial metal occurs. The V-Al\nbond is completely broken in this transition as long as the bonding orbitals\nare fully depopulated by the holes donated from Ti substitution. In other\nwords, the Dirac electrons in $\\mathbf{VAl_3}$ are protected by the V-Al bond\nwhose molecular orbital is their bonding gravity center. Our understanding on\nthe interrelations among electron count, chemical bond and electronic\nproperties in topological semimetals suggests a rational approach to search\nrobust, chemical-bond-protected topological materials.",
        "positive": "Heat Transfer between Weakly Coupled Systems: We study the heat transfer between weakly coupled systems with flat\ninterface. We present simple analytical results which can be used to estimate\nthe heat transfer coefficient. As applications we consider the heat transfer\nacross solid-solid contacts, and between a membrane (graphene) and a solid\nsubstrate (amorphous SiO2). For the latter system the calculated value of the\nheat transfer coefficient is in good agreement with the value deduced from\nexperimental data."
    },
    {
        "anchor": "Modification of the magnetic and electronic properties of the\n  graphene-Ni(111) interface via halogens intercalation: Electronic decoupling of graphene from metallic and semiconducting substrates\nvia intercalation of different species is one of the widely used approaches in\nstudies of graphene. In the present work the modification of the electronic and\nmagnetic properties of graphene on ferromagnetic Ni(111) layer via\nintercalation of halogen atoms (X = F, Cl, Br) is studied using the\nstate-of-the-art density-functional theory approach. It is found that in all\ngr/X/Ni(111) intercalation systems a graphene layer is fully electronically\ndecoupled from the ferromagnetic substrate; however, different kind (electron\nor hole) and level of doping can be achieved. Despite the extremely small\nmagnetic moment of C-atoms in graphene observed after halogens intercalation,\nthe sizeable spin-splitting up to $35$ meV for the linearly dispersing graphene\n$\\pi$ bands is found. The obtained theoretical data bring new ideas on the\nformation of the graphene-ferromagnet interfaces where spin polarized\nfree-standing graphene layer can be formed with the possible application of\nthese systems in electronics and spintronics.",
        "positive": "Surface-termination dependent magnetism and strong perpendicular\n  magnetocrystalline anisotropy of a FeRh (001) thin film: A density-functional\n  study: Magnetism of FeRh (001) films strongly depends on film thickness and surface\nterminations. While magnetic ground state of bulk FeRh is G-type\nantiferromagnetism, the Rh-terminated films exhibit ferromagnetism with strong\nperpendicular MCA whose energy +2.1 meV/$\\Box$ is two orders of magnitude\ngreater than 3$d$ magnetic metals, where $\\Box$ is area of two-dimensional unit\ncell. While Goodenough-Kanamori-Anderson rule on the superexchange interaction\nis crucial in determining the magnetic ground phases of FeRh bulk and thin\nfilms, the magnetic phases are results of interplay and competition between\nthree mechanisms - the superexchange interaction, the Zener direct-interaction,\nand magnetic energy gain."
    },
    {
        "anchor": "Mechanical strain induced topological phase changes of few layer\n  ZrTe$_5$: Understanding the topological aspects of the band structure of solids has\nfundamentally changed our appreciation of their properties. The layered, van\nder Waals transition-metal pentatelluride ZrTe$_5$ has proven on numerous\noccasions to be an excellent candidate for the study of controllable\ntopological phase transitions. Here, we investigate the topological phase\ndiagrams of monolayer and bilayer forms of ZrTe$_5$, under mechanical\ndeformations using \\textit{ab initio} techniques. We find that mechanical\ndeformation can close the monolayer's topological gap, while the bilayer\nexhibits richer phase diagram, including both topological insulating, trivial\nmetallic and insulating phases. The bilayer is predicted to be on the\ntopological phase boundary. We also address the preparation of monolayers,\nusing \\emph{ab initio} simulations and experimental scanning tunneling\nmicroscopy measurements. We confirm that while monolayer ZrTe$_5$ is difficult\nto exfoliate without compromising its crystalline structure, bilayers offer a\nmore stable alternative, revealing the complexities and limitations of using\ngold substrates for monolayer exfoliation.",
        "positive": "Amorphous carbon films in direct current magnetron sputtering from\n  regenerative sooting discharge: We present results of carbon coatings on metal substrates in cylindrical\nhollow cathode (CHC) direct current magnetron sputtering. This is a new\ntechnique of making amorphous carbon film in CHC magnetron sputtering from\nregenerative sooting discharge. The carbon films are deposited on Cu and Al\nsubstrates in Ne atmosphere and compared with the films of carbon soot on the\nsame materials produced from conventional arc discharge between graphite\nelectrodes at 80 Angstrom in He background. The films are characterized using\nonline emission, Raman, and Fourier transform infrared spectroscopy; X-ray\ndiffraction (XRD) and Scanning electron microscopy (SEM). Raman spectroscopy\nreveals the existence of graphite and diamond like structures from arc\ndischarge while in CHC magnetron sputtering, graphite like structures are\ndominant. XRD pattern from arc discharge show precipitates of Al4C3 of\nrhombohedral and hexagonal types in nanometer ranges for aluminum sample and\nprobable formation of diamond and hexagonal carbon in copper whilst in\nmagnetron sputtering we get amorphous carbon films. SEM images of surface show\ncollection of loose agglomerates of carbon particles in arc discharge whereas\nfor magnetron sputtering structures are regular with smooth edges and fine\ngrains."
    },
    {
        "anchor": "Large-scale ab initio simulations based on systematically improvable\n  atomic basis: We present a first-principles computer code package (ABACUS) that is based on\ndensity functional theory and numerical atomic basis sets. Theoretical\nfoundations and numerical techniques used in the code are described, with focus\non the accuracy and transferability of the hierarchical atomic basis sets as\ngenerated using a scheme proposed by Chen, Guo and He [J. Phys.:Condens. Matter\n\\textbf{22}, 445501 (2010)]. Benchmark results are presented for a variety of\nsystems include molecules, solids, surfaces, and defects. All results show that\nthe ABACUS package with its associated atomic basis sets is an efficient and\nreliable tool for simulating both small and large-scale materials.",
        "positive": "CALPHAD-based modelling of the temperature-composition-structure\n  relationship during physical vapor deposition of Mg-Ca thin films: The temperature-dependent composition and phase formation during physical\nvapor deposition (PVD) of Mg-Ca thin films is modelled using a CALPHAD-based\napproach. Considering the Mg and Ca sublimation fluxes calculated based on the\nvapor pressure obtained by employing equilibrium thermochemical calculations,\nexperimentally observed synthesis temperature trends in thin film composition\nand phase formation are reproduced. The model is a significant step towards\nunderstanding how synthesis parameters control composition and thereby phase\nformation in PVD of metals with high vapor pressures."
    },
    {
        "anchor": "Density functional study of electronic structure, elastic and optical\n  properties of MNH$_2$ (M=Li, Na, K, Rb): We report systematic first principles density functional study on the\nelectronic structure, elastic and optical properties of nitrogen based solid\nhydrogen storage materials LiNH$_2$, NaNH$_2$, KNH$_2$, and RbNH$_2$. The\nground state structural properties are calculated by using standard density\nfunctional theory and also dispersion corrected density functional theory. We\nfind that van der Waals interactions are dominant in LiNH$_2$ whereas they are\nrelatively weak in other alkali metal amides. The calculated elastic constants\nshow that all the compounds are mechanically stable and LiNH$_2$ is found to be\nstiffer material among the alkali metal amides. The melting temperatures are\ncalculated and which follows the order RbNH$_2$ $<$ KNH$_2$ $<$ NaNH$_2$ $<$\nLiNH$_2$. The electronic band structure is calculated by using the Tran-Blaha\nmodified Becke-Johnson potential and found that all the compounds are\ninsulators with a considerable band gap. The [NH$_2$]$^-$ derived states are\ncompletely dominating in the entire valence band region while the metal atom\nstates occupy the conduction band. The calculated band structure is used to\nanalyze the different interband optical transitions occur between valence and\nconduction bands. Our calculations show that these materials have considerable\noptical anisotropy.",
        "positive": "Ferromagnetism in magnetically doped III-V semiconductors: The origin of ferromagnetism in semimagnetic III-V materials is discussed.\nThe indirect exchange interaction caused by virtual electron excitations from\nmagnetic impurity level in the bandgap to the valence band can explain\nferromagnetism in GaAs(Mn) no matter samples are degenerated or not. Formation\nof ferromagnetic clusters and percolation picture of phase transition describes\nwell all available experimental data and allows to predict the Mn-composition\ndependence of transition temperature in wurtzite (Ga,In,Al)N epitaxial layers."
    },
    {
        "anchor": "Photo-induced phase-transitions in complex solids: Photo-induced phase-transitions (PIPTs) driven by highly cooperative\ninteractions are of fundamental interest as they offer a way to tune and\ncontrol material properties on ultrafast timescales. Due to strong correlations\nand interactions, complex quantum materials host several fascinating PIPTs such\nas light-induced charge density waves and ferroelectricity and have become a\ndesirable setting for studying these PIPTs. A central issue in this field is\nthe proper understanding of the underlying mechanisms driving the PIPTs. As\nthese PIPTs are highly nonlinear processes and often involve multiple time and\nlength scales, different theoretical approaches are often needed to understand\nthe underlying mechanisms. In this review, we present a brief overview of PIPTs\nrealized in complex materials, followed by a discussion of the available\ntheoretical methods with selected examples of recent progress in understanding\nof the nonequilibrium pathways of PIPTs.",
        "positive": "Insight into the partitioning and clustering mechanism of rare-earth\n  cations in alkali aluminoborosilicate glasses: Rare-earth (RE) containing alkali aluminoborosilicate glasses find\nincreasingly broad technological applications, with their further development\nonly impeded by yet-poor understanding of coordination environment and\nstructural role of RE ions in glasses. In this work we combine free induction\ndecay (FID)-detected electron paramagnetic resonance (EPR), electron spin echo\nenvelope modulation (ESEEM), and MAS NMR spectroscopies, to examine the\ncoordination environment and the clustering tendencies of RE3+ in a series of\nperalkaline aluminoborosilicate glasses co-doped with Nd2O3 (0.001-0.1 mol%)\nand 5 mol% La2O3. Quantitative EPR spectral analysis reveals three different\nNd3+ forms coexisting in the glasses: isolated Nd3+ centers, dipole-coupled Nd\nclusters (Nd-O-X-O-Nd, where X = Si/B/Al), and spin-exchange-coupled Nd\nclusters, (Nd-O-Nd) and (Nd-O-La-O-Nd). Extensive RE clustering is observed at\nhigh RE2O3 concentrations, with more than 90% REs converting to dipole- and\nexchange-coupled Nd clusters already at [RE2O3] = 0.01 mol%. ESEEM analysis of\nthe EPR-detectable Nd centers indicates a Na/Si-rich environment (four Na+ per\nNd3+) for the isolated Nd3+ centers and the Na/Si/B-rich environment (2-3 Na+\nand 1-2 boron per each Nd3+) for the dipole-coupled Nd clusters, while the\nEPR-undetectable exchanged-coupled RE clusters are predicted to exist in a\nNa/B-rich environment. The RE clustering induces nano-scale glass phase\nseparation, while the Na/B-rich environment of the RE clusters implies a\ndepletion of the same elements from the remaining host glass. Based on our\nresults, we develop a mechanistic model that explains the high tendency of RE3+\nto form clusters in alkali aluminoborosilicate glasses."
    },
    {
        "anchor": "Crystal structure and local ordering in epitaxial\n  Fe$_{100-x}$Ga$_x$/MgO(001) films: In this work we present a study of the structural properties of Fe$_{100-x}$\nGa$_x$ grown by Molecular Beam Epitaxy on Mg0(100). We combine long range and\nlocal/chemically selective X-ray probes (X-ray Diffraction and X-ray absorption\nspectroscopy) together with real space imaging by means of Transmission\nElectron Microscopy and surface sensitive $in situ$ Reflected High Energy\nElectron Diffraction. For substrate temperature $T_s$ below 400 $^o$C we obtain\n$bcc$ films while, for $x \\approx$ 24 and $T_s \\geq$ 400$^o$C the nucleation of\nthe $fcc$ phase is observed. For both systems a Ga anticlustering or local\nrange ordering phenomenon appears. The Ga/Fe composition in the first and\nsecond coordination shells of the $bcc$ films is different from that expected\nfor a random Ga distribution and is close to a D0$_3$-like ordered phase,\nleading to a minimization of the number of Ga-Ga pairs. On the other side, a\ntrue long-range D0$_3$ phase is not observed indicating that atomic ordering\nonly occurs at a local scale. Overall, the epitaxial growth procedure presented\nin this work, first, avoids the formation of a long range ordered D0$_3$ phase,\nwhich is known to be detrimental magnetostrictive properties, and second,\ndemonstrates the possibility of growing $fcc$ films at temperatures much\nsmaller than those required to obtain bulk $fcc$ samples.",
        "positive": "Spectroscopic Evidence on Realization of a Genuine Topological Nodal\n  Line Semimetal in LaSbTe: The nodal line semimetals have attracted much attention due to their unique\ntopological electronic structure and exotic physical properties. A genuine\nnodal line semimetal is qualified by the presence of Dirac nodes along a line\nin the momentum space that are protected against the spin-orbit coupling. In\naddition, it requires that the Dirac points lie close to the Fermi level\nallowing to dictate the macroscopic physical properties. Although the material\nrealization of nodal line semimetals have been theoretically predicted in\nnumerous compounds, only a few of them have been experimentally verified and\nthe realization of a genuine nodal line semimetal is particularly rare. Here we\nreport the realization of a genuine nodal line semimetal in LaSbTe. We\ninvestigated the electronic structure of LaSbTe by band structure calculations\nand angle-resolved photoemission (ARPES) measurements. Taking spin-orbit\ncoupling into account, our band structure calculations predict that a nodal\nline is formed in the boundary surface of the Brillouin zone which is robust\nand lies close to the Fermi level. The Dirac nodes along the X-R line in\nmomentum space are directly observed in our ARPES measurements and the energies\nof these Dirac nodes are all close to the Fermi level. These results constitute\nclear evidence that LaSbTe is a genuine nodal line semimetal,providing a new\nplatform to explore for novel phenomena and possible applications associated\nwith the nodal line semimetals."
    },
    {
        "anchor": "Detection of nanocracks on double fluoride rare earth crystal surface: Predicted earlier, microcracks on the crystal surface of both finely\ndispersed $LiYF_4$ powders and single crystals of the Van Vleck paramagnet $%\nLiTmF_4$ were detected by using the NMR Cryoporometry and Atomic-Force\nMicroscopy technique.",
        "positive": "Topotactic-hydrogen forms chains in $AB$O$_2$ nickelate superconductors: Despite enormous experimental and theoretical efforts, obtaining generally\naccepted conclusions regarding the intrinsic magnetic and electronic properties\nof superconducting nickelates remains exceptionally challenging. Experiments\nshow a significant degree of uncertainty, indicating hidden factors in the\nsynthesized films, which call for further investigations. One of those \"hidden\nfactors\" is the possibility of intercalating hydrogen during the chemical\nreduction process from Nd(La)NiO$_3$ to Nd(La)NiO$_2$ using CaH$_2$. While\nhydrogen has been detected in experimental samples, not much is known about its\ndistribution through the crystal and its influence on the electronic\nenvironment. Here, we show the tendency toward the formation of one-dimensional\nhydrogen chains in infinite-layers LaNiO$_2$ superconductors using\ndensity-functional theory (DFT) supplemented by dynamical mean-field theory\n(DMFT). The formation of such hydrogen chains induces a coexistence of\ndifferent oxidation states of Ni and competing magnetic phases, and possibly\nexplains the recently observed charge order states in nickelate\nsuperconductors. Furthermore, it contributes to the difficulty of synthesizing\nhomogeneous nickelates and determining their ground states. The smoking gun to\ndetect excess hydrogen in nickelates are flat phonon modes, which are infrared\nactive and quite insensitive to the exact arrangement of the H atoms."
    },
    {
        "anchor": "Non-linear alloying and strain effects on trivial-topological and\n  semimetal-semiconductor transitions in Bi$_{1-x}$Sb$_x$: Applying the approximate DFT-1/2 quasiparticle scheme, band structure\nunfolding, and generalized quasichemical approximation to describe chemical and\nstructural disorder, we investigate the electronic structure of\nBi$_{1-x}$Sb$_x$ alloys from first principles. We calculate the important\nenergy levels near the Fermi energy versus the Sb concentration $x$ where the\ntrivial-topological (TT) and semimetal-semiconductor (SMSC) transitions occur.\nWe demonstrate that the energy variation of the relevant states deviates\nsignificantly from linear behavior and that the bowings are important to\ncorrectly describe the critical compositions. The influence of strain on the\nenergy levels is briefly discussed. It is concluded that the type or sign of\nstrain applied on antimony atoms during the growth of the alloy should be\nheavily dependent on its composition.",
        "positive": "Charge Carrier Mediation and Ferromagnetism induced in MnBi6Te10\n  Magnetic Topological Insulators by antimony doping: A new kind of intrinsic magnetic topological insulators (MTI) MnBi2Te4 family\nhave shed light on the observation of novel topological quantum effect such as\nquantum anomalous Hall effect (QAHE). However, the strong anti-ferromagnetic\n(AFM) coupling and high carrier concentration in the bulk hinder the practical\napplications. In closely related materials MnBi4Te7 and MnBi6Te10, the\ninterlayer magnetic coupling is greatly suppressed by Bi2Te3 layer\nintercalation. However, AFM is still the ground state in these compounds. Here\nby magnetic and transport measurements, we demonstrate that Sb substitutional\ndopant plays a dual role in MnBi6Te10, which can not only adjust the charge\ncarrier type and the concentration, but also induce the solid into a\nferromagnetic (FM) ground state. AFM ground state region which is also close to\nthe charge neutral point can be found in the phase diagram of Mn(SbxBi1-x)6Te10\nwhen x ~ 0.25. An intrinsic FM-MTI candidate is thus demonstrated, and it may\ntake a step further for the realization of high-quality and high-temperature\nQAHE and the related topological quantum effects in the future."
    },
    {
        "anchor": "Optimized Effective Potential Method in Current-Spin Density Functional\n  Theory: Current-spin density functional theory (CSDFT) provides a framework to\ndescribe interacting many-electron systems in a magnetic field which couples to\nboth spin- and orbital-degrees of freedom. Unlike in usual (spin-) density\nfunctional theory, approximations to the exchange-correlation energy based on\nthe model of the uniform electron gas face problems in practical applications.\nIn this work, explicitly orbital-dependent functionals are used and a\ngeneralization of the Optimized Effective Potential (OEP) method to the CSDFT\nframework is presented. A simplifying approximation to the resulting integral\nequations for the exchange-correlation potentials is suggested. A detailed\nanalysis of these equations is carried out for the case of open-shell atoms and\nnumerical results are given using the exact-exchange energy functional. For\nzero external magnetic field, a small systematic lowering of the total energy\nfor current-carrying states is observed due to the inclusion of the current in\nthe Kohn-Sham scheme. For states without current, CSDFT results coincide with\nthose of spin density functional theory.",
        "positive": "High Luminescence in Small Si/SiO2 Nanocrystals: A Theoretical Study: In recent years many experiments have demonstrated the possibility to achieve\nefficient photoluminescence from Si/SiO2 nanocrystals. While it is widely known\nthat only a minor portions of the nanocrystals in the samples contribute to the\nobserved photoluminescence, the high complexity of the Si/SiO2 interface and\nthe dramatic sensitivity to the fabrication conditions make the identification\nof the most active structures at the experimental level not a trivial task.\nFocusing on this aspect we have addressed the problem theoretically, by\ncalculating the radiative recombination rates for different classes of\nSi-nanocrystals in the diameter range of 0.2-1.5 nm, in order to identify the\nbest conditions for optical emission. We show that the recombination rates of\nhydrogenated nanocrystals follow the quantum confinement feature in which the\nnanocrystal diameter is the principal quantity in determining the system\nresponse. Interestingly, a completely different behavior emerges from the\nOH-terminated or SiO2-embedded nanocrystals, where the number of oxygens at the\ninterface seems intimately connected to the recombination rates, resulting the\nmost important quantity for the characterization of the optical yield in such\nsystems. Besides, additional conditions for the achievement of high rates are\nconstituted by a high crystallinity of the nanocrystals and by high confinement\nenergies (small diameters)."
    },
    {
        "anchor": "Strain driven conducting domain walls in a Mott insulator: Rewritable nanoelectronics offers new perspectives and potential to both\nfundamental research and technological applications. Such interest has driven\nthe research focus into conducting domain walls: pseudo 2D conducting channels\nthat can be created, positioned, and deleted in situ. However, the study of\nconductive domain walls is largely limited to wide-gap ferroelectrics, where\nthe conductivity typically arises from changes in charge carrier density, due\nto screening charge accumulation at polar discontinuities. This work shows\nthat, in narrow-gap correlated insulators with strong charge lattice coupling,\nlocal strain gradients can drive enhanced conductivity at the domain walls,\nremoving polar discontinuities as a criteria for conductivity. By combining\ndifferent scanning probe microscopy techniques, we demonstrate that the domain\nwall conductivity in GaV4S8 does not follow the established screening charge\nmodel but rather arises from the large surface reconstruction across the\nJahn-Teller transition and the associated strain gradients across the domain\nwalls. This mechanism can turn any structural, or even magnetic, domain wall\nconducting, if the electronic structure of the host is susceptible to local\nstrain gradients, drastically expanding the range of materials and phenomena\nthat may be applicable to domain wall based nanoelectronics.",
        "positive": "Morphology of graphene thin film growth on SiC(0001): Epitaxial films of graphene on SiC(0001) are interesting from a basic physics\nas well as applications-oriented point of view. Here we study the emerging\nmorphology of in-vacuo prepared graphene films using low energy electron\nmicroscopy (LEEM) and angle-resolved photoemission (ARPES). We obtain an\nidentification of single and bilayer of graphene film by comparing the\ncharacteristic features in electron reflectivity spectra in LEEM to the PI-band\nstructure as revealed by ARPES. We demonstrate that LEEM serves as a tool to\naccurately determine the local extent of graphene layers as well as the layer\nthickness."
    },
    {
        "anchor": "Diffuse Neutron Scattering Study of Relaxor Ferroelectric\n  (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3(PZN-xPT): Diffuse neutron scattering is a valuable tool to obtain information about the\nsize and orientation of the polar nanoregions that are a characteristic feature\nof relaxor ferroelectrics. In this paper, we present new diffuse scattering\nresults obtained on Pb(Zn1/3Nb2/3)O3 (PZN for short) and\n(1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3(PZN-xPT)single crystals (with x=4.5 and 9%),\naround various Bragg reflections and along three symmetry directions in the\n[100]-[011] zone. Diffuse scattering is observed around reflections with mixed\nindices, (100), (011) and (300), and along transverse and diagonal directions\nonly. No diffuse scattering is found in longitudinal scans. The diffuse\nscattering peaks can be fitted well with a Lorentzian function, from which a\ncorrelation length is extracted. The correlation length increases with\ndecreasing temperatures down to the transition at Tc, first following a\nCurie-Weiss law, then departing from it and becoming flat at very low\ntemperatures. These results are interpreted in terms of three temperature\nregions: 1) dynamic polarization fluctuations (i.e. with a finite lifetime) at\nhigh temperatures, 2) static polarization reorientations (condensation of polar\nnanoregions) that can still reorient as a unit (relaxor behavior) at\nintermediate temperatures and 3) orientational freezing of the polar\nnanoregions with random strain fields in pure PZN or a structural phase\ntransition in PZN-xPT at low temperatures. The addition of PT leads to a\nbroadening of the diffuse scattering along the diagonal ([111]) relative to the\ntransverse ([100]) direction, indicating a change in the orientation of the\npolar regions. Also, with the addition of PT, the polar nanoregions condense at\na higher temperature above Tc.",
        "positive": "Efficient determination of solid-state phase equilibrium with the\n  Mutli-Cell Monte Carlo method: Building on our previously introduced Multi-cell Monte Carlo (MC)^2 method\nfor modeling phase coexistence, this paper provides important improvements for\nefficient determination of phase equilibria in solids. The (MC)^2 method uses\nmultiple cells, representing possible phases. Mass transfer between cells is\nmodeled virtually by solving the mass balance equation after the composition of\neach cell is changed arbitrarily. However, searching for the minimum free\nenergy during this process poses a practical problem. The solution to the mass\nbalance equation is not unique away from equilibrium and consequently the\nalgorithm is in risk of getting trapped in nonequilibrium solutions. Therefore,\na proper stopping condition for (MC)^2 is currently lacking. In this work, we\nintroduce a consistency check via a predictor-corrector algorithm to penalize\nsolutions that do not satisfy a necessary condition for equivalence of chemical\npotentials and steer the system towards finding equilibrium. The most general\nacceptance criteria for (MC)^2 is derived starting from the isothermic-isobaric\nGibbs Ensemble for mixtures. Using this ensemble, translational MC moves are\nadded to include vibrational excitations as well as volume MC moves to ensure\nthe condition of constant pressure and temperature entirely with a MC approach,\nwithout relying on any other method for relaxation of these degrees of freedom.\nAs a proof of concept the method is applied to two binary alloys with\nmiscibility gaps and a model quaternary alloy, using classical interatomic\npotentials."
    },
    {
        "anchor": "New Ferromagnetic Nitrides CaN and SrN and their synthesis process: We introduce new type of ferromagnets, CaN and SrN, which were designed using\nfirst-principles calculations. These are half-metallic ferromagnets and they\nhave magnetic moments of 1 $\\mu_{\\rm B}$ per chemical formula unit. Out of the\ntypical structures of binary compounds, the rock-salt structure is the most\nstable form for both CaN and SrN. The majority of the magnetic moment of these\ncompound originates from the N sites since the $p$ states of N are\nspin-polarized. Their formation energies were calculated and the results show\nthat it should be feasible to synthesize these materials. The structural\nstability of CaN was confirmed by performing first-principles molecular\ndynamics simulations. We propose a synthesis process for CaN basd on the\nfirst-principles.",
        "positive": "Structural effects on the spin-state transition in epitaxially strained\n  LaCoO$_3$ films: Using density functional theory within the LSDA + U method, we investigate\nthe effect of strain on the spin state and magnetic ordering in perovskite\nlanthanum cobaltite, LaCoO3. We show that, while strain-induced changes in\nlattice parameters are insufficient to stabilize a non-zero spin state,\nadditional heteroepitaxial symmetry constraints -- in particular the\nsuppression of octahedral rotations -- stabilize a ferromagnetic\nintermediate-spin state. By comparing with experimental data for the bulk\nmaterial, we calculate an upper bound on the Hubbard U value, and describe the\nrole that the on-site Coulomb interaction plays in determining the spin-state\nconfiguration."
    },
    {
        "anchor": "Mn12-acetate film pattern generated by photolithography methods: We demonstrate a straightforward way to lithographically fabricate\nMn12-acetate (Mn12O12(CH3COO)16(H2O)4 2CH3COOH 4H2O) thin film patterns on\nSi/SiO2 surfaces, a significant step in light of the chemical volatility of\nthis organic complex. Atomic force microscopy (AFM) images of the film patterns\nallow the determination of the pattern dimensions. X-ray photoelectron\nspectroscopy (XPS) data indicate that the patterned material is the intact\nMn12-acetate complex. Magnetic measurements of the Mn12-acetate film confirm\nthat the film properties are reminiscent of crystalline Mn12-acetate,\nsuggesting that this approach can be used to fabricate lithographically\npatterned devices of Mn12-acetate.",
        "positive": "Thermally excited multi-band conduction in LaAlO3/SrTiO3\n  heterostructures exhibiting magnetic scattering: Magnetotransport measurements of charge carriers at the interface of a\nLaAlO3/SrTiO3 heterostructure with 26 unit cells of LaAlO3 show Hall resistance\nand magnetoresistance which at low and high temperatures is described by a\nsingle channel of electron-like charge carriers. At intermediate temperatures,\nwe observe non-linear Hall resistance and positive magnetoresistance,\nestablishing the presence of at least two electron-like channels with\nsignificantly different mobilities and carrier concentrations. These channels\nare separated by 6 meV in energy and their temperature dependent occupation and\nmobilities are responsible for the observed transport properties of the\ninterface. We observe that one of the channels has a mobility that decreases\nwith decreasing temperature, consistent with magnetic scattering in this\nchannel."
    },
    {
        "anchor": "Heteroepitaxial growth of high optical quality, wafer-scale van der\n  Waals heterostrucutres: Transition metal dichalcogenides (TMDs) are materials that can exhibit\nintriguing optical properties like a change of the bandgap from indirect to\ndirect when being thinned down to a monolayer. Well-resolved narrow excitonic\nresonances can be observed for such monolayers, however only for materials of\nsufficient crystalline quality, so far mostly available in the form of\nmicrometer-sized flakes. A further significant improvement of optical and\nelectrical properties can be achieved by transferring the TMD on hexagonal\nboron nitride (hBN). To exploit the full potential of TMDs in future\napplications, epitaxial techniques have to be developed that not only allow to\ngrowlarge-scale, high-quality TMD monolayers, but allow to perform the growth\ndirectly on large-scale epitaxial hBN. In this work we address this problem and\ndemonstrate that MoSe2 of high optical quality can be directly grown on\nepitaxial hBN on an entire two-inch wafer. We developed a combined growth theme\nfor which hBN is first synthesized at high temperature by Metal Organic Vapor\nPhase Epitaxy (MOVPE) and as a second step MoSe2 is deposited on top by\nMolecular Beam Epitaxy (MBE) at much lower temperatures. We show that this\nstructure exhibits excellent optical properties, manifested by narrow excitonic\nlines in the photoluminescence spectra. Moreover, the material is homogeneous\non the area of the whole two-inch wafer, with only +/-0.14 meV deviation of\nexcitonic energy. Our mixed growth technique may guide the way for future\nlarge-scale production of high quality TMD/hBN heterostructures.",
        "positive": "Conduction Electron Scattering and Spin-Flipping at Sputtered Co/Ni\n  Interfaces: Current-perpendicular-to-plane magnetoresistance (CPP-MR) measurements let us\nquantify conduction electron scattering and spin-flipping at a sputtered\nferromagnetic/ferromagnetic (F1/F2 = Co/Ni) interface, with important\nconsequences for CPP-MR and spin-torque experiments with perpendicular\nanisotropy. We use ferromagnetically coupled ([Ni/Co]xn)Ni multilayers, and\nPy-based, symmetric double exchange-biased spin-valves (DEBSVs) containing\ninserts of ferromagnetically coupled ([Co/Ni]xn)Co or ([Ni/Co]xn)Ni\nmultilayers, to derive Co/Ni interface specific resistances AR(Co/Ni)(Up) =\n0.03 (+0.02)(-0.03) f-ohm-m^2 and AR(Co/Ni)(down) = 1.00 +/- 0.07 f-ohm-m^2,\nand interface spin-flipping parameter delta(Co/Ni) = 0.35 +/- 0.05. The\nspecific resistances are consistent with our no-free-parameter calculations for\nan interface thickness between 2 and 4 monolayers (ML) that is compatible with\nexpectations."
    },
    {
        "anchor": "Density Functional Theory Study of the Hydrogen Evolution Reaction in\n  Haeckelite Boron Nitride Quantum Dots: To satisfy rising energy needs and to handle the forthcoming worldwide\nclimate transformation, major research attention has been drawn to\nenvironmentally friendly, renewable, and abundant energy resources. Hydrogen\nplays an ideal and significant role is such resources, due to its\nnon-carbon-based energy and production through clean energy. In this work, we\nhave explored the catalytic activity of a newly predicted haeckelite boron\nnitride quantum dot (haeck-BNQD), constructed from the infinite BN sheet, for\nits utilization in hydrogen production. Density functional theory calculations\nare employed to investigate geometry optimization, electronic and adsorption\nmechanism of haeck-BNQD using Gaussian16 package, employing the hybrid B3LYP\nand wB97XD functionals, along with 6- 31G(d,p) basis set. A number of physical\nquantities such as HOMO/LUMO energies, the density of states, hydrogen atom\nadsorption energies, Mulliken populations, Gibbs free energy, work functions,\noverpotentials, etc., have been computed and analyzed in the context of the\ncatalytic performance of haeck-BNQD for the hydrogen-evolution reaction (HER).\nBased on our calculations, we predict that the best catalytic performance will\nbe obtained for H adsorption on top of the squares or the octagons of\nhaeck-BNQD. We hope that our prediction of the most active catalytic sites on\nhaeck-BNQD for HER will be put to test in future experiments.",
        "positive": "Evolution of self-assembled InAs/Gas(001) quantum dots grown by\n  growth-interrupted molecular beam epitaxy: Self-assembled InAs quantum dots (QDs) grown on GaAs(001) surface by\nmolecular beam epitaxy under continuous and growth-interruption modes exhibit\ntwo families of QDs, quasi-3D (Q3D) and 3D QDs, whose volume density evolution\nis quantitatively described by a rate-equation kinetic model. The volume\ndensity of small Q3D QDs decreases exponentially with time during the\ninterruption, while the single-dot mean volume of the large QDs increases by\nOstwald ripening. The kinetics of growth involves conversion of quasi-3D to 3D\nQDs at a rate determined by superstress and participation of the wetting layer\nadatoms. The data analysis excludes that quasi-3D QDs are extrinsic surface\nfeatures due to inefficient cooling after growth."
    },
    {
        "anchor": "Carbon films with a novel sp2 network structure: Laser-Arc evaporation of a graphite target has been used to deposit carbon\nfilms that exhibit high hardness (45 GPa) and elastic recovery (85%). High\nResolution Electron Microscopy (HREM) and Electron Energy Loss Spectroscopy\n(EELS) were subsequently used to study the microstructure and bonding of the\nresultant layers. The structure of the films from HREM is seen to consist of a\ndense array of parallel curved graphene sheet segments packed in various\norientations. EELS reveals that the films are comprised of mainly sp2 bonded\ncarbon. The results suggest that a new form of carbon thin film with\nfullerene-like structure can be realised. In order to explain how a\npredominantly sp2 bonded material can exhibit such a high hardness, a simple\nmodel is proposed to correlate the excellent mechanical properties with the\nobserved structure.",
        "positive": "Stress effects on vibrational spectra of a cubic hybrid perovskite: A\n  probe of local strain: Inhomogeneous strain may develop in hybrid organic metal-halide perovskite\nthin films due to thermal expansion mismatch with a fabrication substrate,\npolycrystallinity or even light soaking. Measuring these spatially varying\nstrains is difficult but of prime importance for understanding the effects on\ncarrier mobility, non-radiative recombination, degradation and other\noptoelectronic properties. Local strain can be mapped using the shifts in\nvibrational frequencies using Raman or infrared microscopy. We use density\nfunctional theory to investigate the effect of uniaxial strain on the\nvibrations of pseudo-cubic methylammonium lead iodide (CH$_3$NH$_3$PbI$_3$),\nand identify the vibrational modes most favorable for local strain mapping (86\ncm$^{-1}$, 97 cm$^{-1}$, 1457 cm$^{-1}$, and 1537 cm$^{-1}$) and provide\ncalibration curves. We explain the origin of the frequency changes with strain\nusing dynamical matrix and mode eigenvector analysis and study strain-induced\nstructural changes. We also calculate mode Gr\\\"uneisen parameters, giving\ninformation about anharmonicity and anisotropic negative thermal expansion as\nrecently reported for other phases. Our results provide a basis for strain\nmapping in hybrid perovskites to further the understanding and control of\nstrain, and improve stability and photovoltaic performance."
    },
    {
        "anchor": "Infrared metamaterials by RF sputtered ZnO/Al:ZnO multilayers: Hyperbolic metamaterials create artificial optical anisotropy using metallic\nwires suspended in a dielectric medium, or alternating layers of a metal and\ndielectric. Here we fabricated ZnO/Al:ZnO (AZO) multilayers by the RF magnetron\nsputtering deposition technique. Our fabricated multilayers satisfy the\nconditions required for a type I hyperbolic metamaterial. The optical response\nof individual AZO and ZnO films, as well as the multilayered film were\ninvestigated via angular transmittance and spectroscopic ellipsometry\nmeasurements. The optical response of the multilayered system is predicted\nusing the nonlocal-corrected Effective Medium Approximation (EMA). The\nspectroscopic ellipsometry data of the multilayered system was modeled using a\nuniaxial material model and EMA model. Both theoretical and experimental\nstudies validate the multilayers undergo a hyperbolic transition at a\nwavelength of 2.2 {\\mu}m.",
        "positive": "Nitrogen Contamination in Elastic Neutron Scattering: Nitrogen gas accidentally sealed in a sample container produces various\nspurious effects in elastic neutron scattering measurements. These effects are\nsystematically investigated and the details of the spurious scattering are\npresented."
    },
    {
        "anchor": "Stress transmission in planar disordered solid foams: Stress transmission in planar open-cell cellular solids is analysed using a\nrecent theory developed for marginally rigid granular assemblies. This is made\npossible by constructing a one-to-one mapping between the two systems. General\ntrivalent networks are mapped onto assemblies of rough grains, while networks\nwhere Plateau rules are observed, are mapped onto assemblies of smooth grains.\nThe constitutive part of the stress transmission equations couples the stress\ndirectly to the local rotational disorder of the cellular structure via a new\nfabric tensor. An intriguing consequence of the analysis is that the stress\nfield can be determined in terms of the microstructure alone independent of\nstress-strain information. This redefines the problem of structure-property\nrelationship in these materials and poses questions on the relations between\nthis formalism and elasticity theory. The deviation of the stress transmission\nequations from those of conventional solids has been interpreted in the context\nof granular assemblies as a new state of solid matter and the relevance of this\ninterpretation to the state of matter of cellular solids is discussed.",
        "positive": "Optimized Orthogonal Basis Tight Binding. Application to Iron: The formal link between the linear combination of atomic orbitals approach to\ndensity functional theory and two-center Slater-Koster tight-binding models is\nused to derive an orthogonal $d$-band tight-binding model for iron with only\ntwo fitting parameters. The resulting tight-binding model correctly predicts\nthe energetic ordering of the low energy iron-phases, including the\nferromagnetic BCC, antiferromagnetic FCC, HCP and topologically close-packed\nstructures. The energetics of test structures that were not included in the fit\nare equally well reproduced as those included, thus demonstrating the\ntransferability of the model. The simple model also gives a good description of\nthe vacancy formation energy in the nonmagnetic FCC and ferromagnetic BCC iron\nlattices."
    },
    {
        "anchor": "Three-Dimensional Damage Characterisation in Dual Phase Steel using Deep\n  Learning: High performance sheet metals with a multi-phase microstructure suffer from\ndeformation induced damage formation during forming in the constituent phases\nbut importantly also where these intersect. To capture damage in terms of the\nphysical processes in three dimensions (3D) and its stochastic nature during\ndeformation, two challenges remain to be tackled: First, bridging high\nresolution analysis towards large scales to consider statistical data and,\nsecond, characterising in 3D with a resolution appropriate for sub-micron sized\nvoids at a large scale. Here, we present how this can be achieved using\npanoramic scanning electron microscopy (SEM), metallographic serial sectioning,\nand deep-learning assisted automatic image analysis. This brings together the\n3D evolution of active damage mechanisms with volumetric and environmental\ninformation for thousands of individual damage sites. We also assess potential\nsurface preparation artefacts in 2D analyses. Overall, we find that for the\nmaterial considered here, a dual phase (DP800) steel, martensite cracking is\nthe dominant but not sole origin of deformation induced damage and that for a\nquantitative comparison of damage density, metallographic preparation can\ninduce additional surface damage density far exceeding what is commonly induced\nbetween uniaxial straining steps.",
        "positive": "Geometric Phases in Graphitic Cones: In this article we use a geometric approach to study geometric phases in\ngraphitic cones. The spinor that describes the low energy states near the Fermi\nenergy acquires a phase when transported around the apex of the cone, as found\nby a holonomy transformation. This topological result can be viewed as an\nanalogue of the Aharonov-Bohm effect. The topological analysis is extended to a\nsystem with $n$ cones, whose resulting configuration is described by an\neffective defect."
    },
    {
        "anchor": "Tunneling electron induced rotation of a copper phthalocyanine molecule\n  on Cu(111): The rates of a hindered molecular rotation induced by tunneling electrons are\nevaluated using scattering theory within the sudden approximation. Our approach\nexplains the excitation of copper phthalocyanine molecules (CuPc) on Cu(111) as\nrevealed in a recent measurement of telegraph noise in a scanning tunneling\nmicroscopy (STM) experiment [Schaffert \\textit{et al.}, Nat. Mat. {\\bf 12}, 223\n(2013)]. A complete explanation of the experimental data is performed by\ncomputing the geometry of the adsorbed system, its electronic structure and the\nenergy transfer between tunneling electrons and the molecule's rotational\ndegree of freedom. The results unambiguously show that tunneling electrons\ninduce a frustrated rotation of the molecule. In addition, the theory\ndetermines the spatial distribution of the frustrated rotation excitation,\nconfirming the striking dominance of two out of four molecular lobes in the\nobserved excitation process. This lobe selectivity is attributed to the\ndifferent hybridizations with the underlying substrate.",
        "positive": "Degenerate ground states and nonunique potentials: breakdown and\n  restoration of density functionals: The Hohenberg-Kohn (HK) theorem is one of the most fundamental theorems of\nquantum mechanics, and constitutes the basis for the very successful\ndensity-functional approach to inhomogeneous interacting many-particle systems.\nHere we show that in formulations of density-functional theory (DFT) that\nemploy more than one density variable, applied to systems with a degenerate\nground state, there is a subtle loophole in the HK theorem, as all mappings\nbetween densities, wave functions and potentials can break down. Two weaker\ntheorems which we prove here, the joint-degeneracy theorem and the\ninternal-energy theorem, restore the internal, total and exchange-correlation\nenergy functionals to the extent needed in applications of DFT to atomic,\nmolecular and solid-state physics and quantum chemistry. The joint-degeneracy\ntheorem constrains the nature of possible degeneracies in general many-body\nsystems."
    },
    {
        "anchor": "Phase stability and structural temperature dependence in sodium niobate:\n  A high resolution powder neutron diffraction study: We report investigation of structural phase transitions in technologically\nimportant material sodium niobate as a function of temperature on heating over\n300-1075 K. Our high resolution powder neutron diffraction data show variety of\nstructural phase transitions ranging from non-polar antiferrodistortive to\nferroelectric and antiferroelectric in nature. Discontinuous jump in lattice\nparameters is found only at 633 K that indicates that the transition of\northorhombic antiferroelectric P (space group Pbcm) to R (space group Pbnm)\nphase is first order in nature, while other successive phase transitions are of\nsecond order. New superlattice reflections appear at 680 K (R phase) and 770 K\n(S phase) that could be indexed using an intermediate long-period modulated\northorhombic structure whose lattice parameter along <001> direction is 3 and 6\ntimes that of the CaTiO3-like Pbnm structure respectively. The correlation of\nsuperlattice reflections with the phonon instability is discussed. The critical\nexponent ({\\beta}) for the second order tetragonal to cubic phase transition at\n950 K, corresponds to a value {\\beta}$\\approx 1/3$, as obtained from the\ntemperature variation of order parameters (tilt angle and intensity of\nsuperlattice reflections). It is argued that this exponent is due to a second\norder phase transition close to a tricritical point. Based on our detailed\ntemperature dependent neutron diffraction studies, the phase diagram of sodium\nniobate is presented that resolves existing ambiguities in the literature.",
        "positive": "Study on dielectric behavior of Lithium Tantalate(LT) nano particle\n  filled poly (vinylidene fluoride) (PVDF) nano composite: For pyroelectric detector application materials should have low dielectric\nconstant, high pyroelectric coefficient, large non volatile polarization at\nsmall applied electric field and low specific heat. Large field (greater than\n1200kV/cm) is need to pole ferroelectric polymer poly (vinylidene fluoride)\n(PVDF) and it has low sensitivity compared to other pyroelectric materials. To\nincrease non volatile polarization at low poling field and to increase\npyroelectric coefficient, LiTaO3 (LT) nano particles were added to PVDF matrix\nto make LT/PVDF composite. It is important to study the dielectric properties\nof the composite (to be used in detector application) because dielectric\nconstant varies with volume fraction of filler and with frequency. Nano\ncomposite films of LT/PVDF with different volume fraction (i. e fLT = 0.047,\n0.09 and 0.17) of LT were prepared by dispersing LT nano particles in solution\nof PVDF. The dielectric properties of LT/PVDF composite were studied by varying\nthe volume fraction of LT. The dielectric permittivity of LT/ PVDF composites\nincreased compared to PVDF as the volume fraction of LT increases but the loss\ntangent is almost constant at higher frequency. In low frequency region, for\nfLT = 0.17 the dielectric permittivity of composite is greater than PVDF and\nLT. The dielectric loss tangent is also increased from 0.04 to 0.175 as fLT\nincreases from 0 to 0.17 at 1 kHz. The dielectric permittivity behavior of\ncomposite has been explained using percolation model and space charge\npolarization model."
    },
    {
        "anchor": "Magnetism of 3d transition metal atoms on W(001): submonolayer films: We have investigated random submonolayer films of 3d transition metals on\nW(001). The tight-binding linear muffin-tin orbital method combined with the\ncoherent potential approximation was employed to calculate the electronic\nstructure of the films. We have estimated local magnetic moments and the\nstability of different magnetic structures, namely the ferromagnetic order, the\ndisordered local moments and the non-magnetic state, by comparing the total\nenergies of the corresponding systems. It has been found that the magnetic\nmoments of V and Cr decrease and eventually disappear with decreasing coverage.\nOn the other hand, Fe retains approximately the same magnetic moment throughout\nthe whole concentration range from a single impurity to the monolayer coverage.\nMn is an intermediate case between Cr and Fe since it is non-magnetic at very\nlow coverages and ferromagnetic otherwise.",
        "positive": "Full angular dependence of the spin Hall and ordinary magnetoresistance\n  in epitaxial antiferromagnetic NiO(001)/Pt thin films: We report the observation of the three-dimensional angular dependence of the\nspin Hall magnetoresistance (SMR) in a bilayer of the epitaxial\nantiferromagnetic insulator NiO(001) and the heavy metal Pt, without any\nferromagnetic element. The detected angular-dependent longitudinal and\ntransverse magnetoresistances are measured by rotating the sample in magnetic\nfields up to 11 T, along three orthogonal planes (xy-, yz- and xz-rotation\nplanes, where the z-axis is orthogonal to the sample plane). The total\nmagnetoresistance has contributions arising from both the SMR and ordinary\nmagnetoresistance. The onset of the SMR signal occurs between 1 and 3 T and no\nsaturation is visible up to 11 T. The three-dimensional angular dependence of\nthe SMR can be explained by a model considering the reversible field-induced\nredistribution of magnetostrictive antiferromagnetic S- and T-domains in the\nNiO(001), stemming from the competition between the Zeeman energy and the\nelastic clamping effect of the non-magnetic MgO substrate. From the observed\nSMR ratio, we estimate the spin mixing conductance at the NiO/Pt interface to\nbe greater than $2\\times10^{14}$ ${\\Omega}^{-1}$ $m^{-2}$. Our results\ndemonstrate the possibility to electrically detect the N\\'eel vector direction\nin stable NiO(001) thin films, for rotations in the xy- and xz- planes.\nMoreover, we show that a careful subtraction of the ordinary magnetoresistance\ncontribution is crucial to correctly estimate the amplitude of the SMR."
    },
    {
        "anchor": "Highly-Sensitive Resonance-Enhanced Organic Photodetectors for Shortwave\n  Infrared Sensing: Shortwave infrared (SWIR) has various applications, including night vision,\nremote sensing, and medical imaging. SWIR organic photodetectors (OPDs) offer\nadvantages such as flexibility, cost-effectiveness, and tunable properties,\nhowever, lower sensitivity and limited spectral coverage compared to inorganic\ncounterparts are major drawbacks. Here, we propose a simple yet effective and\nwidely applicable strategy to extend the wavelength detection range of OPD to a\nlonger wavelength, using resonant optical microcavity. We demonstrate a\nproof-of-concept in PTB7-Th:COTIC-4F blend system, achieving external quantum\nefficiency (EQE) > 50 % over a broad spectrum 450 - 1100 nm with a peak\nspecific detectivity (D*) of 1.1E13 Jones at 1100 nm, while cut-off bandwidth,\nspeed, and linearity are preserved. By employing a novel small-molecule\nacceptor IR6, a record high EQE = 35 % and D* = 4.1E12 Jones are obtained at\n1150 nm. This research emphasizes the importance of optical design in\noptoelectronic devices, presenting a considerably simpler method to expand the\nphotodetection range compared to a traditional approach that involves\ndeveloping absorbers with narrow optical gaps.",
        "positive": "Strengthening of copper by carbon nanotubes: The influence of a modifier based on multi walled carbon nanotubes (MWCNT) is\ninvestigated using C11000 copper alloy. The influence of the modifier addition\ninto the melt was investigated using tensile test, hardness measurements, X-ray\ndiffraction method and microstructural investigations. It was evaluated that\nthe yield and tensile strengths of the metal increased due to the\nmicrostructural changes in the formed metal after addition of 0.01wt.% of the\nMWCNTs. It was also evaluated that the addition of mentioned amount of MWCNT\ninto alloy has no influence to the phase composition of the formed metal."
    },
    {
        "anchor": "Manipulating spin wave polarization in synthetic antiferromagnet: Polarization is a key ingredient of all waves, including the electromagnetic\nwave, the acoustic wave, as well as the spin wave. Due to the fixed\nferromagnetic order, the spin wave in ferromagnet is limited to the right\ncircular polarization. The spin wave in antiferromagnet, however, is endowed\nwith the full polarization degree of freedom because of the two identical\nmagnetic sublattices. In the synthetic antiferromagnet, the two magnetic\nsublattices are spatially separated into two sublayers. The circular\npolarization of spin wave is partially locked to the magnetic sublattice of the\nantiferromagnet, thus to the sublayer in synthetic antiferromagnet. Based on\nthis unique polarization-sublayer locking mechanism, we show that both the\ncircular spin wave polarizer and retarder (wave-plate) can be straightforwardly\nrealized using synthetic antiferromagnets by restructuring the sublayers, e.g.\nby removing or capping a portion of a sublayer. Manipulating spin wave\npolarization by geometrical engineering provides a simple yet powerful paradigm\nin harnessing the spin wave polarization for spin information processing.",
        "positive": "Monte Carlo simulation based on dynamic disorder model in organic\n  semiconductors: From bandlike to hopping transport: The dynamic disorder model for charge carrier transport in organic\nsemiconductors has been extensively studied in recent years. Although it is\nsuccessful on determining the value of bandlike mobility in the organic\ncrystalline materials, the incoherent hopping, the typical transport\ncharacteristic in organic semiconductors, cannot be described. In this work,\nthe decoherence process is taken into account via a phenomenological parameter,\nsay decoherence time, and the projective and Monte Carlo method is applied for\nthis model to determine the waiting time and thus the diffusion coefficient. We\nfind the type of transport changes from bandlike to incoherent hopping with a\nsufficiently short decoherence time, which indicates the essential role of\ndecoherence time in determining the type of transport in organics. We have also\ndiscussed the spatial extent of carriers for different decoherence time, and\nthe transition from delocalization (carrier resides in about 10 molecules) to\nlocalization is observed. Based on the experimental results of spatial extent,\nwe estimate the decoherence time in pentacene has the order of 1ps.\nFurthermore, the dependence of diffusion coefficient on decoherence time is\nalso investigated, and corresponding experiments are discussed."
    },
    {
        "anchor": "Anomalous dielectric response at intermixed oxide heterointerfaces: Two-dimensional charge carrier accumulation at oxide heterointerfaces\npresents a paradigm shift for oxide electronics. Like a capacitor, interfacial\ncharge buildup couples to an electric field across the dielectric medium. To\nprevent the so-called polar catastrophe, several charge screening mechanisms\nemerge, including polar distortions and interfacial intermixing which reduce\nthe sharpness of the interface. Here, we examine how atomic intermixing at\noxide interfaces affect the balance between polar distortions and electric\npotential across the dielectric medium. We find that intermixing moves the peak\ncharge distribution away from the oxide/oxide interface; thereby changing the\ndirection of polar distortions away from this boundary with minimal effect on\nthe electric field. This opposing electric field and polar distortions is\nequivalent to the transient phase transition tipping point observed in double\nwell ferroelectrics; resulting in an anomalous dielectric response -- a\npossible signature of local negative differential capacitance, with\nimplications for designing dissipationless oxide electronics.",
        "positive": "Optimizing surface defects for atomic-scale electronics: Si dangling\n  bonds: Surface defects created and probed with scanning tunneling microscopes are a\npromising platform for atomic-scale electronics and quantum information\ntechnology applications. Using first-principles calculations we demonstrate how\nto engineer dangling bond (DB) defects on hydrogenated Si(100) surfaces, which\ngive rise to isolated impurity states that can be used in atomic-scale devices.\nIn particular we show that sample thickness and biaxial strain can serve as\ncontrol parameters to design the electronic properties of DB defects. While in\nthick Si samples the neutral DB state is resonant with bulk valence bands,\nultrathin samples (1-2 nm) lead to an isolated impurity state in the gap;\nsimilar behavior is seen for DB pairs and DB wires. Strain further isolates the\nDB from the valence band, with the response to strain heavily dependent on\nsample thickness. These findings suggest new methods for tuning the properties\nof defects on surfaces for electronic and quantum information applications.\nFinally, we present a consistent and unifying interpretation of many results\npresented in the literature for DB defects on hydrogenated silicon surfaces,\nrationalizing apparent discrepancies between different experiments and\nsimulations."
    },
    {
        "anchor": "A First-Principles Tool to Discover New Pyrometallurgical Refining\n  Options: We demonstrate the opportunities of first-principles density functional\ntheory (DFT) calculations for the development of new metallurgical refining\nprocesses. As such, a methodology based on DFT calculations is developed to\ndiscover new pyrometallurgical refining processes that use the addition of a\nthird element to remove an impurity from a molten host material. As a case\nstudy, this methodology is applied to the refining of lead. The proposed method\npredicts the existing refining routes as well as alternative processes. The\nmost interesting candidate for the removal of arsenic from lead is\nexperimentally verified, which confirms the suitability of the remover element.\nThe method is therefore considered as a useful approach to speed up the\ndiscovery of new pyrometallurgical refining processes, as it provides an\nordered set of interesting candidate remover elements",
        "positive": "Mixed Magnetism for Refrigeration and Energy Conversion: The efficient coupling between lattice degrees of freedom and spin degrees of\nfreedom in magnetic materials can be used for refrigeration and energy\nconversion. This coupling is enhanced in materials exhibiting the giant\nmagnetocaloric effect. First principle electronic structure calculations on\nhexagonal MnFe(P, Si) reveal a new form of magnetism: the coexistence of strong\nand weak magnetism in alternate atomic layers. The weak magnetism of Fe layers\n(disappearance of local magnetic moments at the Curie temperature) is\nresponsible for a strong coupling with the crystal lattice while the strong\nmagnetism in adjacent Mn-layers ensures Curie temperatures high enough to\nenable operation at and above room temperature. Varying the composition on\nthese magnetic sublattices gives a handle to tune the working temperature and\nto achieve a strong reduction of the undesired thermal hysteresis. In this way\nwe design novel materials based on abundantly available elements with\nproperties matched to the requirements of an efficient refrigeration or\nenergy-conversion cycle."
    },
    {
        "anchor": "Displacements of 180-degree domain walls in electroded ferroelectric\n  single crystals: the effect of surface layers on restoring force: Macroscopic properties of ferroelectric samples, including those in form of\nthin films, are, to large extent, influenced by their domain structure. In this\npaper the free energy is calculated for a plate-like sample composed of\nnonferroelectric surface layers and ferroelectric central part with\nantiparallel domains. The sample is provided with electrodes with a defined\npotential difference. The effect of applied field and its small changes on the\nresulting domain structure is discussed. This makes it possible to determine\nthe restoring force acting on domain walls which codetermines dielectric and\npiezoelectric properties of the sample. Calculations of the potential and free\nenergy take into account interactions of opposite surfaces and are applicable\nalso to thin films.",
        "positive": "Mechanism of recrystallization process in epitaxial GaN under dynamic\n  stress field - Atomistic origin of planar defect formation: The mechanism of recrystallization in epitaxial (1000) GaN film, introduced\nby indentation technique, is probed by lattice dynamic studies using Raman\nspectroscopy. The recrystallized region is identified by Micro-Raman area\nmapping. Pop-in bursts in loading lines indicate nucleation of dislocations and\nclimb of dislocations. These processes set in plastic motion of lattice atoms\nunder stress field at the center of indentation for the initiation of\nrecrystallization process. A planar defect migration mechanism is evolved. A\npivotal role of vacancy migration is pointed out, for the first time, as the\nrate limiting factor for the dislocation dynamics initiating the\nrecrystallization process in GaN."
    },
    {
        "anchor": "Reproducibility in Computational Materials Science: Lessons from 'A\n  General-Purpose Machine Learning Framework for Predicting Properties of\n  Inorganic Materials': The integration of machine learning techniques in materials discovery has\nbecome prominent in materials science research and has been accompanied by an\nincreasing trend towards open-source data and tools to propel the field.\nDespite the increasing usefulness and capabilities of these tools, developers\nneglecting to follow reproducible practices creates a significant barrier for\nresearchers looking to use or build upon their work. In this study, we\ninvestigate the challenges encountered while attempting to reproduce a section\nof the results presented in \"A general-purpose machine learning framework for\npredicting properties of inorganic materials.\" Our analysis identifies four\nmajor categories of challenges: (1) reporting computational dependencies, (2)\nrecording and sharing version logs, (3) sequential code organization, and (4)\nclarifying code references within the manuscript. The result is a proposed set\nof tangible action items for those aiming to make code accessible to, and\nuseful for the community.",
        "positive": "Magnetically-Functionalized Self-Aligning Graphene Fillers for\n  High-Efficiency Thermal Management Applications: We report on heat conduction properties of thermal interface materials with\nself-aligning \"magnetic grapheme\" fillers. Graphene enhanced nano-composites\nwere synthesized by an inexpensive and scalable technique based on liquid-phase\nexfoliation. Functionalization of graphene and few-layer-graphene flakes with\nFe3O4 nanoparticles allowed us to align the fillers in an external magnetic\nfield during dispersion of the thermal paste to the connecting surfaces. The\nfiller alignment results in a strong increase of the apparent thermal\nconductivity and thermal diffusivity through the layer of nano-composite\ninserted between two metallic surfaces. The self-aligning \"magnetic grapheme\"\nfillers improve heat conduction in composites with both curing and non-curing\nmatrix materials. The thermal conductivity enhancement with the oriented\nfillers is a factor of two larger than that with the random fillers even at the\nlow ~1 wt. % of graphene loading. The real-life testing with computer chips\ndemonstrated the temperature rise decrease by as much as 10oC with use of the\nnon-curing thermal interface material with ~1 wt. % of the oriented fillers.\nOur proof-of-concept experiments suggest that the thermal interface materials\nwith functionalized graphene and few-layer-graphene fillers, which can be\noriented during the composite application to the surfaces, can lead to a new\nmethod of thermal management of advanced electronics."
    },
    {
        "anchor": "Transitions in ZnS and CdSe quantum dots and wave-function symmetry: Excitation energies for wurtzite spherical ZnS and CdSe quantum dots in the\nrange of 40-4000 atoms were calculated using empirical pseudopotentials and a\nreal-space basis. The energies are compared to experiments and other\npseudopotential models. For ZnS quantum dots, squared transition dipole sums\nwere computed efficiently, without the need for full wave functions of the\nexcited states; and some transition dipole calculations include the effects of\nan approximate electron-hole Coulomb potential. Squared transition dipole sums\nfrom the highest energy linear dipole like valence states to the lowest excited\nstate were computed as a function of dot size. The model predicts that the per\natom dipole transition sum decreases with quantum dot size for those\ntransitions. The mixing of even and odd angular components and charge asymmetry\nof the wave functions affect the dipole transition strengths. The total\noscillator strength for the lowest energy transition region increases with size\nat small radii, resembling the pattern recently observed experimentally for\nCdSe quantum dots. We examined the role of wave-function angular momentum for\ntransitions to conduction band surface states.",
        "positive": "Multicaloric effect in multiferroic Y2CoMnO6: We have investigated multiple caloric effects in multiferroic Y2CoMnO6.\nPolycrystalline sample prepared by solid state method has shown a ferromagnetic\nCurie temperature 75 K with second order phase transition; a maximum magneto\nentropy change -$\\Delta$S_{Mmax}) of ~ 7.3 J/kg K with reasonable relative\ncooling power 220 J/kg is found without thermal and magnetic hysteresis loss.\nElectric field driven entropy change (-$\\Delta$S_{Emax}) of ~ 0.26 J/m^3 K\nobtained using the Maxwells relation and estimated magnetically induced total\ntemperature change of 5.45 K around Curie temperature that confirms the\nmulticaloric effect in the sample."
    },
    {
        "anchor": "Reliable Synthesis of Large-Area Monolayer WS2 Single Crystals, Films,\n  and Heterostructures with Extraordinary Photoluminescence Induced by Water\n  Intercalation: Two-dimensional (2D) transition metal dichalcogenides (TMDs) hold great\npotential for future low-energy optoelectronics owing to their unique\nelectronic, optical, and mechanical properties. Chemical vapor deposition (CVD)\nis the technique widely used for the synthesis of large-area TMDs. However, due\nto high sensitivity to the growth environment, reliable synthesis of monolayer\nTMDs via CVD remains challenging. Here we develop a controllable CVD process\nfor large-area synthesis of monolayer WS2 crystals, films, and in-plane\ngraphene-WS2 heterostructures by cleaning the reaction tube with hydrochloric\nacid, sulfuric acid and aqua regia. The concise cleaning process can remove the\nresidual contaminates attached to the CVD reaction tube and crucibles, reducing\nthe nucleation density but enhancing the diffusion length of WS2 species. The\nphotoluminescence (PL) mappings of a WS2 single crystal and film reveal that\nthe extraordinary PL around the edges of a triangular single crystal is induced\nby ambient water intercalation at the WS2-sapphire interface. The extraordinary\nPL can be controlled by the choice of substrates with different wettabilities.",
        "positive": "Signatures of the Adler-Bell-Jackiw chiral anomaly in a Weyl Fermion\n  semimetal: Weyl semimetals provide the realization of Weyl fermions in solid-state\nphysics. Among all the physical phenomena that are enabled by Weyl semimetals,\nthe chiral anomaly is the most unusual one. Here, we report signatures of the\nchiral anomaly in the magneto-transport measurements on the first Weyl\nsemimetal TaAs. We show negative magnetoresistance under parallel electric and\nmagnetic fields, that is, unlike most metals whose resistivity increases under\nan external magnetic field, we observe that our high mobility TaAs samples\nbecome more conductive as a magnetic field is applied along the direction of\nthe current for certain ranges of the field strength. We present systematically\ndetailed data and careful analyses, which allow us to exclude other possible\norigins of the observed negative magnetoresistance. Our transport data,\ncorroborated by photoemission measurements, first-principles calculations and\ntheoretical analyses, collectively demonstrate signatures of the Weyl fermion\nchiral anomaly in the magneto-transport of TaAs."
    },
    {
        "anchor": "Prediction of an Extended Ferroelectric Clathrate: Using first-principles calculations, we predict a lightweight\nroom-temperature ferroelectric carbon-boron framework in a host/guest clathrate\nstructure. This ferroelectric clathrate, with composition ScB$_3$C$_3$,\nexhibits high polarization density and low mass density compared with widely\nused commercial ferroelectrics. Molecular dynamics simulations show spontaneous\npolarization with a moderate above-room-temperature T$_c$ of $\\sim$370 K, which\nimplies large susceptibility and possibly large electrocaloric and\npiezoelectric constants at room temperature. Our findings open the possibility\nfor a new class of ferroelectric materials with potential across a broad range\nof applications.",
        "positive": "High Throughput Screening of Transition Metal Binuclear Site for N2\n  Fixation: Great enthusiasm in single atom catalysts (SACs) for the N2 reduction\nreaction (NRR) has been aroused by the discovery of Metal (M)-Nx as a promising\ncatalytic center. However,the performance of available SACs,including poor\nactivity and selectivity,is far away from the industrial requirement because of\nthe inappropriate adsorption behaviors of the catalytic centers. Through the\nfirst principles high throughput screening, we find that the rational\nconstruction of Fe-Fe dual atom centered site distributed on graphite carbon\nnitride (Fe2/gCN) compromises the ability to adsorb N2H and NH2, achieving the\nbest NRR performance among 23 different transition metal (TM) centers. Our\nresults show that Fe2/gCN can achieve a Faradic efficiency of 100% for NH3\nproduction. Impressively, the limiting potential of Fe2/gCN is estimated as low\nas -0.13 V, which is hitherto the lowest value among the reported theoretical\nresults. Multiple level descriptors (excess electrons on the adsorbed N2 and\nintegrated crystal orbital Hamilton population) shed light on the origin of NRR\nactivity from the view of energy, electronic structure, and basic\ncharacteristics. As a ubiquitous issue during electrocatalytic NRR, ammonia\ncontamination originating from the substrate decomposition can be surmounted.\nOur predictions offer a new platform for electrocatalytic synthesis of NH3,\ncontributing to further elucidate the structure-performance correlations."
    },
    {
        "anchor": "Lateral Solid Phase Epitaxy of Yttrium Iron Garnet: Solid phase epitaxy is a crystallization technique used to produce high\nquality thin films. Lateral solid phase epitaxy furthermore enables the\nrealization of non-planar structures, which are interesting, e.g., in the field\nof spintronics. Here, we demonstrate lateral solid phase epitaxy of yttrium\niron garnet over an artificial edge, such that the crystallization direction is\nperpendicular to the initial seed. We use single crystalline garnet seed\nsubstrates partially covered by a \\ch{SiO_x} film to study the lateral\ncrystallization over the \\ch{SiO_x} mesa. The yttrium iron garnet layer retains\nthe crystal orientation of the substrate not only when in direct contact with\nthe substrate, but also across the edge on top of the \\ch{SiO_x} mesa. By\ncontrolling the crystallization dynamics it is possible to almost completely\nsuppress the formation of polycrystals and to enable epitaxial growth of single\ncrystalline yttrium iron garnet on top of mesas made from arbitrary materials.\nFrom a series of annealing experiments, we extract an activation energy of\n\\SI{2.8}{eV} and a velocity prefactor of \\SI{5.1e13}{nm/s} for the lateral\nepitaxial crystallization along the <$100$> direction. Our results pave the way\nto engineer single crystalline non-planar yttrium iron garnet structures with\ncontrolled crystal orientation.",
        "positive": "Thermodynamic theory of dislocation/grain boundary interaction: The thermodynamic theory of dislocation/grain boundary interaction, including\ndislocation pile-up against, absorption by, and transfer through the grain\nboundary, is developed for nonuniform plastic deformations in polycrystals. The\ncase study is carried out on the boundary conditions affecting work hardening\nof a bicrystal subjected to plane constrained shear for three types of grain\nboundaries: (i) impermeable hard grain boundary, (ii) grain boundary that\nallows dislocation transfer without absorption, (iii) grain boundary that\nabsorbs dislocations and allows them to pass later."
    },
    {
        "anchor": "Exceeding the Shockley-Queisser limit within the detailed balance\n  framework: The Shockley-Queisser limit is one of the most fundamental results in the\nfield of photovoltaics. Based on the principle of detailed balance, it defines\nan upper limit for a single junction solar cell that uses an absorber material\nwith a specific band gap. Although methods exist that allow a solar cell to\nexceed the Shockley-Queisser limit, here we show that it is possible to exceed\nthe Shockley-Queisser limit without considering any of these additions. Merely\nby introducing an absorptivity that does not assume that every photon with an\nenergy above the band gap is absorbed, efficiencies above the Shockley-Queisser\nlimit are obtained. This is related to the fact that assuming optimal\nabsorption properties also maximizes the recombination current within the\ndetailed balance approach. We conclude that considering a finite thickness for\nthe absorber layer allows the efficiency to exceed the Shockley-Queisser limit,\nand that this is more likely to occur for materials with small band gaps.",
        "positive": "Electronic band structure changes across the antiferromagnetic phase\n  transition of exfoliated MnPS$_3$ probed by $\u03bc$-ARPES: Exfoliated magnetic 2D materials enable versatile tuning of magnetization,\ne.g., by gating or providing proximity-induced exchange interaction. However,\ntheir electronic band structure after exfoliation has not been probed, most\nlikely due to their photochemical sensitivity. Here, we provide micron-scale\nangle-resolved photoelectron spectroscopy of the exfoliated intralayer\nantiferromagnet MnPS$_3$ above and below the N\\'{e}el temperature down to one\nmonolayer. The favorable comparison with density functional theory calculations\nenables to identify the orbital character of the observed bands. Consistently,\nwe find pronounced changes across the N\\'{e}el temperature for bands that\nconsist of Mn 3d and 3p levels of adjacent S atoms. The deduced orbital mixture\nindicates that the superexchange is relevant for the magnetic interaction.\nThere are only minor changes between monolayer and thicker films demonstrating\nthe predominant 2D character of MnPS$_3$. The novel access is transferable to\nother MPX$_3$ materials (M: transition metal, P: phosphorus, X: chalcogenide)\nproviding a multitude of antiferromagnetic arrangements."
    },
    {
        "anchor": "Freestanding \u03c7_3-Borophene Nanoribbons: A Density Functional Theory\n  Investigation: Experimentally observation of borophene nanoribbons (BNRs) motivated us to\ncarry out a comprehensive investigation on BNRs, decomposed from {\\chi}_3\nsheet, using density functional theory. Our results show that the stability and\nalso the electrical and magnetic properties of the ribbons are strongly\ndependent on the edge configuration. We have studied two categories of ribbons:\nXBNRs, and YBNRs. The first one is a nonmagnetic metal with armchair shape\nedge, while YBNRs can be magnetic or nonmagnetic related to the edge shape.\nYBNRs have four different edge types and we show that two of them are magnetic\n( a- and b-type edges) but others are nonmagnetic (c- and d-type edges). There\nare 10 distinct configurations by arranging the different edges of YBNRs. 10\npercent of YBNRs are polarized asymmetrically at the edges leading to the loss\nof degeneracy of spin-up and spin-down bands in the antiferromagnetic\nconfiguration. 40 percent of YBNRs have one magnetic edge which can be a\npromising candidate for spintronic applications due to the separation of the\nspin in the real space in addition to the energy space. Electronic transmission\nproperties of the ribbons are also studied and found that transmission channels\nare suppressed in edges of XBNRs due to electron localization.",
        "positive": "Comment on pyramidal structure formation at the interface between III/V\n  semiconductors and silicon: GaP/Si(100) is considered as pseudomporphic virtual substrate for III/V-on-Si\nintegration in order to reduce defects related to polar-on-nonpolar\nheteroepitaxy. The atomic structure of the GaP/Si(100) heterointerface is\ndecisive to yield low defect densities and its dependence on nucleation\nconditions is still under debate. Recently, Beyer et al. suggested the\nformation of a 'pyramidal' structure as a general mechanism at\npolar-on-nonpolar interfaces [A. Beyer et al., Chem. Mat. 28, 3265 (2016)].\nHowever, their DFT studies neglected the dependence of the calculated\ninterfacial energies on appropriate chemical potentials and their findings are\ncontradictory to recent and past experimental data."
    },
    {
        "anchor": "Genuine driving voltage on polarization fatigue in (Pb,La)(Zr,Ti)O3\n  antiferroelectric thin films: The polarization fatigue in (Pb0.97La0.02)(Zr0.95Ti0.05)O3 (PLZT)\nantiferroelectric thin films deposited onto silicon wafers is studied by\ninvestigating the effect of the peak/average/effective cycling voltage through\nvarying the waveform of the electrical excitation. Interestingly, it is found\nthat the fatigue endurance of the film is determined by the effective voltage\nof the external driving excitation rather than by the peak or average voltages.\nOur results can be well explained in the framework of the local phase\ndecomposition model and indicate that the effective voltage should be\nconsidered as the genuine driving voltage determining the polarization fatigue\nin PLZT antiferroelectric films.",
        "positive": "Electronic origin of melting T-P curves of alkali metals with negative\n  slope and minimum: Group I elements - alkali metals Li, Na, K, Rb and Cs - are examples of\nsimple metals with one s electron in the valence band. Under pressure these\nelements display unusually complex structural behaviour transforming from\nclose-packed to low symmetry open structures. Unexpectedly complex form was\nfound for melting curves of alkalis under compression with initial increasing\nin accordance to Lindemann criterion and further decreasing to very low melting\npoint. To understand complex and low symmetry structures in compressed alkalis\na transformation of the electron energy levels was suggested which involves an\noverlap between the valence band and outer core electrons. Within the model of\nthe Fermi sphere - Brillouin zone interaction one can understand the complex\nmelting curve of alkalis."
    },
    {
        "anchor": "Layer number and stacking order-dependent thermal transport in\n  molybdenum disulfide with sulfur vacancies: Recent theoretical works on two-dimensional molybdenum disulfide, MoS$_2$,\nwith sulfur vacancies predict that the suppression of thermal transport in\nMoS$_2$ by point defects is more prominent in monolayers and becomes negligible\nas layer number increases. Here, we investigate experimentally the thermal\ntransport properties of two-dimensional molybdenum disulfide crystals with\ninherent sulfur vacancies. We study the first-order temperature coefficients of\ninterlayer and intralayer Raman modes of MoS$_2$ crystals with different layer\nnumbers and stacking orders. The in-plane thermal conductivity ($\\kappa$) and\ntotal interface conductance per unit area ($ g $) across the 2D\nmaterial-substrate interface of mono-, bi- and tri-layer MoS$_2$ samples are\nmeasured using the micro-Raman thermometry. Our results clearly demonstrate\nthat the thermal conductivity is significantly suppressed by sulfur vacancies\nin monolayer MoS$_2$. However, this reduction in $\\kappa$ becomes less evident\nas the layer number increases, confirming the theoretical predictions. No\nsignificant variation is observed in the $\\kappa$ and $ g $ values of 2H and 3R\nstacked bilayer MoS$_2$ samples.",
        "positive": "Adsorption and dissociation of hydrogen molecules on bare and\n  functionalized carbon nanotubes: We investigated interaction between hydrogen molecules and bare as well as\nfunctionalized single-wall carbon nanotubes (SWNT) using first-principles plane\nwave method. We found that the binding energy of the H$_{2}$ physisorbed on the\nbare SWNT is very weak, and can be enhanced neither by increasing the curvature\nof the surface through radial deformation, nor by the coadsorption of Li atom\nthat makes the semiconducting tube metallic. Though the bonding is strengthened\nupon adsorption directly to Li atom, yet its nature continues to be\nphysisorption. However, the character of the bonding changes dramatically when\nSWNT is functionalized by the adsorption of Pt atom. Single H$_{2}$ is\nchemisorbed to Pt atom on the SWNT either dissociatively or molecularly. If\nPt-SWNT bond is weakened either by displacing Pt from bridge site to a specific\nposition or by increasing number of the adsorbed H$_{2}$, the dissociative\nadsorption of H$_{2}$ is favored. For example, out of two adsorbed H$_{2}$,\nfirst one can be adsorbed dissociatively, second one is chemisorbed\nmolecularly. The nature of bonding is weak physisorption for the third adsorbed\nH$_{2}$. Palladium also promotes the chemisorption of H$_{2}$ with relatively\nsmaller binding energy. Present results reveal the important effect of\ntransition metal atom adsorbed on SWNT and advance our understanding of the\nmolecular and dissociative adsorption of hydrogen for efficient hydrogen\nstorage."
    },
    {
        "anchor": "GdN Nanoisland-Based GaN Tunnel Junctions: We show that GdN nanoislands can enhance inter-band tunneling in GaN PN\njunctions by several orders of magnitude, enabling low optical absorption\nlow-resistance tunnel junctions (specific resistivity 1.3 X 10-3 {\\Omega}-cm2)\nfor various optoelectronic applications. We exploit the ability to overgrow\nhigh quality GaN over GdN nanoislands to create new nanoscale heterostructure\ndesigns that are not feasible in planar epitaxy. GdN nanoisland assisted\ninter-band tunneling was found to enhance tunneling in both of the polar\norientations of GaN. Tunnel injection of holes was confirmed by low temperature\noperation of GaN p-n junction with a tunneling contact layer, showing strong\nelectroluminescence down to 20K. The availability of tunnel junctions with\nnegligible absorption could not only improve the efficiency of existing\noptoelectronic devices significantly, but also enable new electronic and\noptical devices based on wide band gap materials.",
        "positive": "Probe Skyrmion phases and dynamics in MnSi via the magnetoelectric\n  effect in a composite configuration: We have developed a sensitive technique to probe the magnetic skyrmion phases\nand dynamics by employing the interfacial coupling effect in a magnetoelectric\ncomposite configuration. The study on a MnSi single crystal sample using this\ntechnique provides clear evidences for the skyrmion lattice phase and\ncoexistence of skyrmion and conical phase. Above the Curie temperature TC, a\nregion with strong spin fluctuation is revealed as well. By tuning the density\nof Skyrmion or disorder, a transition from the skyrmion lattice to\nskyrmion-conical coexisting phase is observed. The observation is in good\nagreement with a theoretical model which predicts the dissipation behavior in\nthe coexistence phase."
    },
    {
        "anchor": "Copper underpotential deposition on boron nitride nanomesh: The boron nitride nanomesh is a corrugated monolayer of hexagonal boron\nnitride (h-BN) on Rh(111), which so far has been studied mostly under ultrahigh\nvacuum conditions. Here, we investigate how copper underpotential deposition\n(upd) can be used to quantify defects in the boron nitride monolayer and to\nassess the potential window of the nanomesh, which is important to explore its\nfunctionality under ambient and electrochemical conditions. In dilute sulfuric\nacid, the potential window of h-BN/Rh(111) is close to 1 volt, i.e. larger than\nthat of the Rh substrate, and is limited by molecular hydrogen evolution on the\nnegative and by oxidative removal on the positive side. From copper upd on\npristine h-BN/Rh(111) wafer samples, we estimate a collective defect fraction\non the order of 0.08-0.7% of the geometric area, which may arise from line and\npoint defects in the h-BN layer that are created during its chemical vapour\ndeposition. Overpotential deposition (opd) is demonstrated to have significant\nconsequences on the defect area. We hypothesise that this non-innocent Cu\nelectrodeposition involves intercalation originating at initial defects,\ncausing irreversible delamination of the h-BN layer; this effect may be used\nfor 2D material nanoengineering. On the relevant timescale, upd itself does not\nalter the defect area on repeated cycling; therefore, metal upd may find use as\na general tool to determine the collective defect area in hybrids between 2D\nmaterials and various substrate metals.",
        "positive": "Melting of alloys along grain boundaries: We discuss melting of alloys along grain boundaries as a free boundary\nproblem for two moving solid-liquid interfaces. One of them is the melting\nfront and the other is the solidification front. The presence of the triple\njunction plays an important role in controlling the velocity of this process.\nThe interfaces strongly interact via the diffusion field in the thin liquid\nlayer between them. In the liquid film migration (LFM) mechanism the system\nchooses a more efficient kinetic path, which is controlled by diffusion in the\nliquid film on relatively short distances. However, only weak coherency strain\nenergy is the effective driving force for LFM in the case of melting of\none-phase alloys.\n  The process with only one melting front would be controlled by the very slow\ndiffusion in the mother solid phase on relatively large distances."
    },
    {
        "anchor": "Reply to \"Comment on `Theory of Phonon-Assisted Adsorption in Graphene:\n  Many-Body Infrared Dynamics' \": Based on a new self-energy for atom-phonon interaction, preceding Comment\nargues about the insufficiency of the mathematical techniques within the\nIndependent Boson Model (IBM) to study physisorption in graphene membranes. In\nthis Reply, we show that the new self-energy reported in the Comment is a\nperturbative expansion approximated for a 2-phonon process, severely divergent\nfor membrane sizes larger than 100 nm and within its current mathematical form,\nill-suited for investigating the physics of physisorption in graphene\nmicromembranes. Additionally, we provide with further evidence of the\nadsorption rate within the IBM that further reinforces the physical soundness\nof the mathematical techniques reported in Phys. Rev. B 100, 075429 (2019).",
        "positive": "Large-scale Ocean-based or Geothermal Power Plants by Thermoelectric\n  Effects: Heat resources of small temperature difference are easily accessible, free\nand unlimited on earth. Thermoelectric effects provide the technology for\nconverting these heat resources directly into electricity. We present designs\nof electricity generators based on thermoelectric effects and using heat\nresources of small temperature difference, e.g., ocean water at different\ndepths and geothermal sources, and conclude that large-scale power plants based\non thermoelectric effects are feasible and economically competitive. The key\nobservation is that the power factor of thermoelectric materials, unlike the\nfigure of merit, can be improved by orders of magnitude upon laminating good\nconductors and good thermoelectric materials. The predicted large-scale power\nplants based on thermoelectric effects, if validated, will have a global\neconomic and social impact for its scalability, and the renewability, free and\nunlimited supply of heat resources of small temperature difference on earth."
    },
    {
        "anchor": "Evidence of delocalized excitons in amorphous solids: We studied the temperature dependence of the absorption coefficient of\namorphous SiO$_2$ in the range from 8 to 17.5~eV obtained by Kramers-Kronig\ndispersion analysis of reflectivity spectra. We demonstrate the main excitonic\nresonance at 10.4~eV to feature a close Lorentzian shape red-shifting with\nincreasing temperature. This provides a strong evidence of excitons being\ndelocalized notwithstanding the structural disorder intrinsic to the amorphous\nsystem. Excitons turn out to be coupled to an average phonon mode of 83~meV\nenergy.",
        "positive": "Weak field magnetoresistance of narrow-gap semiconductors InSb: The magnetoresistance of InSb has been intensively investigated. The\nexperiments we perform here focus on weak field magnetoresistance of InSb thin\nfilm. We investigate the magnetoresistance of InSb films in perpendicular,\ntilted as well as parallel magnetic field. Our results verify the previous\nobservations concerning weak localization effect in InSb thin film. Moreover,\nwe systematically study the anisotropy of magnetoresistance of InSb. We find\nthat the existence of in-plane field can effectively suppress the weak\nlocalization effect of InSb film. We fit the experimental data with two types\nof models, the match between data and model is excellent. From the fitting\nprocedure, we get information about phase coherence time, spin-orbit scattering\ntime. The information about Zeeman effect and sample roughness are also\nextracted from the fitting procedure."
    },
    {
        "anchor": "Engineering mass transport properties in oxide ionic and mixed ionic\n  electronic thin film ceramic conductors for energy applications: New emerging disciplines such as Nanoionics and Iontronics are dealing with\nthe exploitation of mesoscopic size effects in materials, which become visible\n(if not predominant) when downsizing the system to the nanoscale. Driven by the\nworldwide standardisation of thin film deposition techniques, the access to\nradically different properties than those found in the bulk macroscopic systems\ncan be accomplished. This opens up promising approaches for the development of\nadvanced microdevices, by taking advantage of the nanostructural deviations\nfound in nanometre sized, interface dominated materials compared to the ideal\nrelaxed structure of the bulk. A completely new set of functionalities can be\nexplored, with implications in many different fields such as energy conversion\nand storage, or information technologies. This manuscript reviews the\nstrategies, employed and foreseen, for engineering mass transport properties in\nthin film ceramics, with the focus in oxide ionic and mixed ionic electronic\nconductors and their application in micro power sources.",
        "positive": "Giant excitonic absorption and emission in two-dimensional group-III\n  nitrides: Absorption and emission of pristine-like semiconducting monolayers of BN,\nAlN, GaN, and InN are here systematically studied by ab-initio methods. We\ncalculate the absorption spectra for in-plane and out-of-plane light\npolarization including quasiparticle and excitonic effects. Chemical trends\nwith the cation of the absorption edge and the exciton binding are discussed in\nterms of the band structures. Exciton binding energies and localization radii\nare explained within the Keldysh model for excitons in two dimensions. The\nstrong excitonic effects are due to the interplay of low dimensionality,\nconfinement effects, and reduced screening. We find exciton radiative lifetimes\nranging from tenths of picoseconds (BN) to tenths of nanoseconds (InN) at room\ntemperature, thus making 2D nitrides, especially InN, promising materials for\nlight-emitting diodes and high-performance solar cells."
    },
    {
        "anchor": "Atomistic simulation of the FEBID-driven growth of iron-based\n  nanostructures: The growth of iron-containing nanostructures in the process of focused\nelectron beam-induced deposition (FEBID) of Fe(CO)$_5$ is studied by means of\natomistic irradiation-driven molecular dynamics (IDMD) simulations. The\ngeometrical characteristics (lateral size, height and volume), morphology and\nmetal content of the grown nanostructures are analyzed at different irradiation\nand precursor replenishment conditions corresponding to the electron-limited\nand precursor-limited regimes (ELR & PLR) of FEBID. A significant variation of\nthe deposit's morphology and elemental composition is observed with increasing\nthe electron current from 1 to 4 nA. At low beam current (1 nA) corresponding\nto the ELR and a low degree of Fe(CO)$_5$ fragmentation, the nanogranular\nstructures are formed which consist of isolated iron clusters embedded into an\norganic matrix. In this regime, metal clusters do not coalesce with increasing\nelectron fluence, resulting in relatively low metal content of the\nnanostructures. A higher beam current of 4 nA corresponding to the PLR\nfacilitates the precursor fragmentation and the coalescence of metal clusters\ninto a dendrite-like structure with the size corresponding to the primary\nelectron beam. The IDMD simulations enable atomistic-level predictions on the\nnanoscopic characterization of the initial phase of nanostructure growth in the\nFEBID process. These predictions can be verified in high-resolution\ntransmission electron microscopy experiments.",
        "positive": "Limits of Elemental Contrast by Low Energy Electron Point Source\n  Holography: Motivated by the need for less destructive imaging of nanostructures, we\npursue point-source in-line holography (also known as point projection\nmicroscopy, or PPM) with very low energy electrons (-100 eV). This technique\nexploits the recent creation of ultrasharp and robust nanotips, which can field\nemit electrons from a single atom at their apex, thus creating a path to an\nextremely coherent source of electrons for holography. Our method has the\npotential to achieve atom resolved images of nanostructures including\nbiological molecules. We demonstrate a further advantage of PPM emerging from\nthe fact that the very low energy electrons employed experience a large elastic\nscattering cross section relative to many-keV electrons. Moreover, the\nvariation of scattering factors as a function of atom type allows for enhanced\nelemental contrast. Low energy electrons arguably offer the further advantage\nof causing minimum damage to most materials. Model results for small molecules\nand adatoms on graphene substrates, where very small damage is expected,\nindicate that a phase contrast is obtainable between elements with\nsignificantly different Z-numbers. For example, for typical setup parameters,\natoms such as C and P are discernible, while C and N are not."
    },
    {
        "anchor": "Alerts in High-resolution TEM characterization of perovskite material: High-resolution TEM (HRTEM) is a powerful tool for structure\ncharacterization. However, methylammonium lead iodide (MAPbI3) perovskite is\nhighly sensitive to electron beams and easily decompose into lead iodide\n(PbI2). Universal misidentifications that PbI2 is incorrectly labeled as\nperovskite are widely exist in HRTEM characterization, which would negatively\naffect the development of perovskite research field. Here misidentifications in\nMAPbI3 perovskite calibration are summarized, classified and corrected based on\ncorresponding electron diffraction (ED) simulations. Corresponding\ncrystallographic parameters of intrinsic tetragonal MAPbI3 and the confusable\nhexagonal PbI2 are also presented clearly. Finally, the method of proper phase\nidentification and some ways to control the radiation damage in HRTEM are\nprovided. This work paves the way to avoid misleadings in HRTEM\ncharacterization of perovskite and other electron beam-sensitive materials in\nthe future.",
        "positive": "On the origin of metal-insulator transitions in the parent compounds of\n  ruthenium-pnictide superconductors: We study the interplay of the structural phase transition, flat electronic\nband dispersion, and metal-to-insulator transition (MIT) in the parent\ncompounds of the Ru-pnictide superconductors by using first-principles\ncalculations. Our electron and phonon calculations reveal that Ru(P,As) undergo\nMIT accompanied by orthorhombic to monoclinic distortion at low temperature,\nbut RuSb stays orthorhombic and metallic in agreement with the experimental\nfindings. We find that although small monoclinic distortion can remove the van\nHove singularity at the Fermi level, it does not immediately gap out the Fermi\nsurface and a large value of monoclinic distortion is necessary for a clear MIT\nsuggesting the possibility of an intermediate pseudogapped monoclinic metallic\nphase. Furthermore, we predict a light-induced two-step insulator-to-metal and\nstructural transitions in the monoclinic phases of RuP and RuAs, which can be\ntested in future ultrafast pump-probe experiments as an alternative ideal play\nground to VO$_2$."
    },
    {
        "anchor": "Magnetization pinning in conducting films demonstrated using broadband\n  ferromagnetic resonance: The broadband microstrip ferromagnetic resonance technique has been applied\nfor detection and characterization of a magnetic inhomogeneity in a film\nsample. In the case of a 100nm thick Permalloy film an additional magnetically\ndepleted top sub-layer, practically unidentifiable by the conventional\nferromagnetic resonance setup, has been detected and characterized. These\nresults have been confirmed by Brillouin light scattering spectroscopy\nrevealing the fact that the optical properties of the additional sub-layer do\nnot differ much from those of the bulk of the film. Subsequent characterization\nof a large number of other presumably single-layer films with thicknesses in\nthe range 30-100nm using the same ferromagnetic resonance technique also\nrevealed the same effect.",
        "positive": "Information limit of 15 pm achieved with bright-field ptychography: It is generally assumed that a high spatial resolution of a microscope\nrequires a large numerical aperture of the imaging lens or detector. In this\nstudy, the information limit of 15 pm is achieved in transmission electron\nmicroscopy using only the bright-field disk (small numerical aperture) via\nmultislice ptychography. The results indicate that high-frequency information\nhas been encoded in the electrons scattered to low angles due to the multiple\nscattering of electrons in the objects, making it possible to break the\ndiffraction limit of imaging via bright-field ptychography."
    },
    {
        "anchor": "Ubiquitous short-range order in multi-principal element alloys: Recent research in multi-principal element alloys (MPEAs) has increasingly\nfocused on the exploration and exploitation of short-range order (SRO) to\nenhance material performance. However, the understanding of SRO formation and\nthe precise tuning of it within MPEAs remains poorly understood, limiting the\ncomprehension of its impact on material properties and impeding the advancement\nof SRO engineering. Here, leveraging advanced additive manufacturing techniques\nthat produce samples with a wide range of cooling rates (up to 10^7 K/s) and an\nimproved quantitative electron microscopy method, we characterize SRO in three\nCoCrNi-based MPEAs to unravel the role of processing route and thermal history\non SRO. Surprisingly, irrespective of the processing and thermal treatment\napplied, all samples exhibit similar levels of SRO, suggesting that prevalent\nSRO may form during the solidification process. Atomistic simulations of\nsolidification verify that local chemical ordering arises in the liquid-solid\ninterface (solidification front) even under the extreme cooling rate of 10^11\nK/s. This phenomenon stems from the swift atomic diffusion in the supercooled\nliquid, which matches or even surpasses the rate of solidification. Therefore,\nSRO is an inherent characteristic of most MPEAs, insensitive to variations in\ncooling rates and annealing treatments typically available in experiments.\nIntegrating thermal treatment with other strategies, such as mechanical\ndeformation and irradiation, might be more effective approaches for harnessing\nSRO to achieve controlled material properties.",
        "positive": "Dislocation climb models from atomistic scheme to dislocation dynamics: We develop a mesoscopic dislocation dynamics model for vacancy-assisted\ndislocation climb by upscalings from a stochastic model on the atomistic scale.\nOur models incorporate microscopic mechanisms of (i) bulk diffusion of\nvacancies, (ii) vacancy exchange dynamics between bulk and dislocation core,\n(iii) vacancy pipe diffusion along the dislocation core, and (iv) vacancy\nattachment-detachment kinetics at jogs leading to the motion of jogs. Our\nmesoscopic model consists of the vacancy bulk diffusion equation and a\ndislocation climb velocity formula. The effects of pipe diffusion and the jog\nstructure on dislocations are incorporated by a Robin boundary condition near\nthe dislocations for the bulk diffusion equation and a new contribution in the\ndislocation climb velocity due to vacancy pipe diffusion driven by the stress\nvariation along the dislocation. Our climb formulation is able to\nquantitatively describe the translation of prismatic loops at low temperatures\nwhen the bulk diffusion is negligible. Using this new formulation, we derive\nanalytical formulas for the climb velocity of a straight edge dislocation and a\nprismatic circular loop. Our dislocation climb formulation can be implemented\nin dislocation dynamics simulations to incorporate all the above four\nmicroscopic mechanisms of dislocation climb."
    },
    {
        "anchor": "Electrochemical Evaluation of Mg and a Mg-Al 5%Zn Metal Rich Primers for\n  Protection of Al-Zn-Mg-Cu Alloy in NaCl: High purity magnesium and a Mg-Al 5wt% Zn metal rich primer (MRP) were\ncompared for their ability to suppress intergranular corrosion (IGC) and\nintergranular stress corrosion cracking (IG-SCC) in peak aged AA 7075-T651 by\nsacrificial anode-based cathodic prevention. Tests were conducted in 0.6 M NaCl\nsolution under full immersion. These evaluations considered the ability of the\nprimer to attain an intermediate negative open circuit potential (OCP) such\nthat the galvanic couple potential with bare aluminum alloy (AA) 7075-T651\nresided below a range of potentials where IGC is prevalent. The ability of the\nprimer to achieve an OCP negative enough that the AA 7075-T651 could be\nprotected by sacrificial anode-based cathodic prevention and the ability to\nsustain this function over time were evaluated as a first step by utilizing a\nNaCl solution. The primers consisted of epoxy resins embedded with either (1)\nMg flake pigments (MgRP) or (2) Mg flake pigments and spherical Al-5 wt.% Zn\ntogether as a composite (MgAlRP). MgRP was an effective coating for cathodic\nprotection but dispensed less anodic charge than the composite MgAlRP.\nCross-sectional analysis demonstrated that some Mg flakes dissolved while\nuniform surface oxidation occurred on the remaining Mg flakes which led to\nimpaired activation. The composite MgAlRP maintained a suitably negative OCP\nover time, remained activated, dispensed high anodic charge, and remained an\nanode in zero resistance ammeter testing. Chemical stability modeling and zero\nresistance ammeter testing suggest that Mg corrosion elevates the pH which\ndissolved aluminum oxides and hydroxide thereby activates the Al-5wt.% Zn\npigments, thereby providing a primary (i.e. Mg corrosion) and secondary process\nto enable superior (activation of Al-5wt%Zn) sacrificial anode-based cathodic\nprotection.",
        "positive": "Finding the reconstructions of semiconductor surfaces via a genetic\n  algorithm: In this article we show that the reconstructions of semiconductor surfaces\ncan be determined using a genetic procedure. Coupled with highly optimized\ninteratomic potentials, the present approach represents an efficient tool for\nfinding and sorting good structural candidates for further electronic structure\ncalculations and comparison with scanning tunnelling microscope (STM) images.\nWe illustrate the method for the case of Si(105), and build a database of\nstructures that includes the previously found low-energy models, as well as a\nnumber of novel configurations."
    },
    {
        "anchor": "Importance of site occupancy and absence of strain glassy phase in\n  Ni$_{2-x}$Fe$_{x}$Mn$_{1.5}$In$_{0.5}$: Martensitic transition temperature steadily decreases in\nNi$_{2-x}$Fe$_{x}$Mn$_{1.5}$In$_{0.5}$ and is completely suppressed at $x$ =\n0.2. Despite suppression of martensitic transition,\nNi$_{1.8}$Fe$_{0.2}$Mn$_{1.5}$In$_{0.5}$ does not display the expected strain\nglassy phase. Instead, a ground state with dominant ferromagnetic interactions\nis observed. A study of structural and magnetic properties of $x$ = 0.2 reveal\nthat the alloy consists of a major Fe rich cubic phase and a minor Fe deficient\nmonoclinic phase favoring a ferromagnetic ground state. This is exactly\nopposite of that observed in Ni$_2$Mn$_{1-y}$Fe$_{y}$In$_{0.5}$ wherein a\nstrain glassy phase is observed for $y$ = 0.1. The change in site symmetry of\nFe when doped for Ni in contrast to Mn in the Heusler composition seems to\nsupport the growth of the ferromagnetic phase.",
        "positive": "Initializing, manipulating and storing quantum information with bismuth\n  dopants in silicon: A prerequisite for exploiting spins for quantum data storage and processing\nis long spin coherence times. Phosphorus dopants in silicon (Si:P) have been\nfavoured as hosts for such spins because of measured electron spin coherence\ntimes (T2) longer than any other electron spin in the solid state: 14 ms at 7\nK. Heavier impurities such as bismuth in silicon (Si:Bi) could be used in\nconjunction with Si:P for quantum information proposals that require two\nseparately addressable spin species. However, the question of whether the\nincorporation of the much less soluble Bi into Si leads to defect species that\ndestroy coherence has not been addressed. Here we show that schemes involving\nSi:Bi are indeed feasible as the electron spin coherence time T2 exceeds 1 ms\nat 10 K. We polarized the Si:Bi electrons and hyperpolarized the I=9/2 nuclear\nspin of 209Bi, manipulating both with pulsed magnetic resonance. The larger\nnuclear spin means that a Si:Bi dopant provides a 20-dimensional Hilbert space\nrather than the four dimensional Hilbert space of an I=1/2 Si:P dopant."
    },
    {
        "anchor": "Fracture Surfaces as Multiscaling Graphs: Fracture paths in quasi-two-dimenisonal (2D) media (e.g thin layers of\nmaterials, paper) are analyzed as self-affine graphs $h(x)$ of height $h$ as a\nfunction of length $x$. We show that these are multiscaling, in the sense that\n$n^{th}$ order moments of the height fluctuations across any distance $\\ell$\nscale with a characteristic exponent that depends nonlinearly on the order of\nthe moment. Having demonstrated this, one rules out a widely held conjecture\nthat fracture in 2D belongs to the universality class of directed polymers in\nrandom media. In fact, 2D fracture does not belong to any of the known kinetic\nroughening models. The presence of multiscaling offers a stringent test for any\ntheoretical model; we show that a recently introduced model of quasi-static\nfracture passes this test.",
        "positive": "Confirmation of the random tiling hypothesis for a decagonal\n  quasicrystal: Mechanisms that stabilize quasicrystals are much discussed but not finally\nresolved. We confirm the random tiling hypothesis and its predictions in a\nfully atomistic decagonal quasicrystal model by calculating the free energy and\nthe phason elastic constants over a wide range of temperatures. The\nFrenkel-Ladd method is applied for the phonon part and an approach of\nuncorrelated phason flips for the configurational part. When lowering the\ntemperature, a phase transition to an approximant occurs. Close to the\ntransition temperature one of the phason elastic constants becomes soft."
    },
    {
        "anchor": "Quantized grain boundary states promote nanoparticle alignment during\n  imperfect oriented attachment: Oriented attachment (OA) has become a well-recognized mechanism for the\ngrowth of metal, ceramic, and biomineral crystals. While many computational and\nexperimental studies of OA have shown that particles can attach with some\nmisorientation then rotate to remove adjoining grain boundaries, the underlying\natomistic pathways for this \"Imperfect OA\" process remain the subject of\ndebate. In this study, molecular dynamics and in situ TEM were used to probe\nthe crystallographic evolution of up to 30 gold and copper nanoparticles during\naggregation. It was found that Imperfect OA occurs because (1) grain boundaries\nbecome quantized when their size is comparable to the separation between\nconstituent dislocations and (2) kinetic barriers associated with the glide of\ngrain boundary dislocations are small. In support of these findings, TEM\nexperiments show the formation of a single crystal aggregate after annealing 9\ninitially misoriented, agglomerated particles with evidence of dislocation slip\nand twin formation during particle/grain alignment. These observations motivate\nfuture work on assembled nanocrystals with tailored defects and call for a\nrevision of Read-Shockley models for grain boundary energies in nanocrystalline\nmaterials.",
        "positive": "Photocatalytic activity enhancement by addition of lanthanum into the\n  BiFeO3 structure and the effect of synthesis method: In this paper, the photocatalytic activity of multiferroics BiFeO3 (BFO) and\nBi0.8La0.2FeO3 (BLFO) nanocrystals with two different morphologies which were\nsynthesized by two different sol-gel (SG) and hydrothermal (HT) methods have\nbeen studied. All the obtained samples were characterized using X-ray\ndiffractometer, Fourier transform infrared spectroscopy, transmission electron\nmicroscopy, UV-vis spectroscopy and vibrating sample magnetometer. Differential\nthermal analysis (DTA) measurements were probed ferroelectric- paraelectric\nfirst-order phase transition (TC) for all samples. Addition of lanthanum\ndecreases the electric phase transition. For photocatalyst application of\nbismuth ferrite, adsorption potential of nanoparticles for methylene blue (MB)\norganic dye was evaluated. The doping of La in the BFO structure enhanced the\nphotocatalytic activity and about 71% degradation of MB dye was obtained under\nvisible irradiation. The magnetic and ferroelectric properties of BLFO\nnanoparticles improve compared to the undoped BiFeO3 nanoparticles. The\nnon-saturation at high applied magnetic field for as-prepared samples by HT is\nrelated to the size and shape of products. This work not only presents an\neffect of lanthanum substitution into the bismuth ferrite structure on the\nphysical properties of BFO, but also compares the synthesis method and its\ninfluence on the photocatalytic activity and multiferroics properties of all\nnanopowders."
    },
    {
        "anchor": "Thermal collapse of spin-polarization in half-metallic ferromagnets: The temperature dependence of the magnetization and spin-polarization at the\nFermi level is investigated for half-metallic ferromagnets. We reveal a new\nmechanism, where the hybridization of states forming the half-metallic gap\ndepends on thermal spin fluctuations and the polarization can drop abruptly at\ntemperatures much lower than the Curie point. We verify this for NiMnSb by\nab-initio calculations. The thermal properties are studied by mapping ab-initio\nresults to an extended Heisenberg model which includes longitudinal\nfluctuations and is solved by a Monte Carlo method.",
        "positive": "Comment on \"Effects of shear methods on shear strengths and deformation\n  modes of two typical transition metal carbides and their unification\": Recently, Chuanying Li, Tao Fu, Xule Li, Hao Hu, and Xianghe Peng in [Phys.\nRev. B 107, 224106] investigated the mechanical behavior of cubic HfC and TaC\nunder simple shear (SS) and pure shear (PS) using first-principles\ncalculations. Unfortunately, the paper contains some serious and fundamental\nflaws in the field of continuum mechanics and nanomechanics. The results\npresented appear to be qualitatively and quantitatively incorrect, they would\nbe correct if we were in the small/linear deformation/strain regime, which we\nare not. A correct description therefore requires a finite/nonlinear\ndeformation/strain apparatus."
    },
    {
        "anchor": "Enhanced electrocatalytic oxygen evolution activity in geometrically\n  designed SrRuO3 thin films: For generation of sustainable, clean and highly efficient energy, the\nelectrocatalytic oxygen evolution reaction represents an attractive platform,\nthus inviting immense research activities in recent years. However, designing\nthe catalyst with enhanced electrocatalytic activity remains one of the major\nchallenges. Here, we examined the oxygen evolution reaction activities of\ngeometrically designed (with and without step-textured morphology) thin films\nof an electrocatalytically active correlated metallic SrRuO3 perovskite grown\non c- and r-plane sapphire substrates. On c-plane sapphire, as compared to the\nuniform surface, the step-textured films endowed with active Ru-sites show\nremarkable decrease in the overpotential (25 mV). Interestingly, the behavior\nis opposite for the r-plane case, highlighting the significance of the active\nsites, in addition with the polar surface termination of selective crystal\nfacets. Density functional theory calculation confirms the favorable energy\nreaction pathway for the active site dependent enhancement in OER. Our strategy\nmight pave the way towards designing the surfaces of various oxide thin films\nfor high performance energy conversion based devices.",
        "positive": "Orthorhombic metal carbide-borides MeC$_2$B$_{12}$ (Me=Mg, Ca, Sr) from\n  first principles: structure, stability and mechanical properties: First principle DFT simulations are employed to study structural and\nmechanical properties of orthorhombic B12-based metal carbide-borides. The\nsimulations predict the existence of Ca- and Sr- based phases with the\nstructure similar to that of experimentally observed earlier compound\nMeC$_2$B$_{12}$. Dynamical stability of both phases is demonstrated, and the\nphase MeC$_2$B$_{12}$ is found to be thermodynamically stable. According to\nsimulations, Ca- and Sr- based phases have significantly enhanced mechanical\ncharacteristics, which suggest their potential application as superhard\nmaterials. Calculated shear and Young moduli of these phases are nearly 250 and\n540 GPa, respectively, and estimated Vickers hardness is 45-55 GPa."
    },
    {
        "anchor": "Structure, stability and electronic properties of tricycle type graphane: We propose a new allotrope of graphane, named as tricycle graphane,with a\n4up/2down UUUDUD hydrogenation in each hexagonal carbon ring,which is different\nfrom previously proposed allotropes with UUDUUD(boat-1) and UUUUDD (boat-2)\ntypes of hydrogenation. Its stability and electronic structures are\nsystematically studied using first-principles method. We find that the tricycle\ngraphane is a stable phase in between the previously proposed chair and stirrup\nallotropes. Its electronic properties are very similar to those of chair,\nstirrup, boat-1, boat-2, and twist-boat allotropes. The negative Gibbs free\nenergy of tricycle graphane is -91 meV/atom, which very close to that of the\nmost stable chair one (-103 meV/atom). Thus, this new two-dimensional\nhydrocarbon may be produced in the process of graphene hydrogenation with a\nrelative high probability compared to other conformers.",
        "positive": "Towards Automating Structural Discovery in Scanning Transmission\n  Electron Microscopy: Scanning transmission electron microscopy (STEM) is now the primary tool for\nexploring functional materials on the atomic level. Often, features of interest\nare highly localized in specific regions in the material, such as ferroelectric\ndomain walls, extended defects, or second phase inclusions. Selecting regions\nto image for structural and chemical discovery via atomically resolved imaging\nhas traditionally proceeded via human operators making semi-informed judgements\non sampling locations and parameters. Recent efforts at automation for\nstructural and physical discovery have pointed towards the use of \"active\nlearning\" methods that utilize Bayesian optimization with surrogate models to\nquickly find relevant regions of interest. Yet despite the potential importance\nof this direction, there is a general lack of certainty in selecting relevant\ncontrol algorithms and how to balance a priori knowledge of the material system\nwith knowledge derived during experimentation. Here we address this gap by\ndeveloping the automated experiment workflows with several combinations to both\nillustrate the effects of these choices and demonstrate the tradeoffs\nassociated with each in terms of accuracy, robustness, and susceptibility to\nhyperparameters for structural discovery. We discuss possible methods to build\ndescriptors using the raw image data and deep learning based semantic\nsegmentation, as well as the implementation of variational autoencoder based\nrepresentation. Furthermore, each workflow is applied to a range of feature\nsizes including NiO pillars within a La:SrMnO$_3$ matrix, ferroelectric domains\nin BiFeO$_3$, and topological defects in graphene. The code developed in this\nmanuscript are open sourced and will be released at\ngithub.com/creangnc/AE_Workflows."
    },
    {
        "anchor": "Auxiliary-field quantum Monte Carlo calculations with multiple-projector\n  pseudopotentials: We have implemented recently developed multiple-projector pseudopotentials\ninto the planewave based auxiliary-field quantum Monte Carlo (pw-AFQMC) method.\nMultiple-projector pseudopotentials can yield smaller planewave cut-offs while\nmaintaining or improving transferability. This reduces the computational cost\nof pw-AFQMC, increasing its reach to larger and more complicated systems. We\ndiscuss the use of non-local pseudopotentials in the separable\nKleinman-Bylander form, and the implementation in pw-AFQMC of the\nmultiple-projector optimized norm-conserving pseudopotential ONCVPSP of Hamann.\nThe accuracy of the method is first demonstrated by equation-of-state\ncalculations of the ionic insulator NaCl and more strongly correlated metal Cu.\nThe method is then applied to calibrate the accuracy of density functional\ntheory (DFT) predictions of the phase stability of recently discovered high\ntemperature and pressure superconducting sulfur hydride systems. We find that\nDFT results are in good agreement with pw-AFQMC, due to near cancellation of\nelectron-electron correlation effects between different structures.",
        "positive": "A Diamagnetic Trap with 1D Camelback Potential: The ability to trap matter is of great importance in experimental physics\nsince it allows isolation and measurement of intrinsic properties of the\ntrapped matter. We present a study of a three dimensional (3D) trap for a\ndiamagnetic rod in a pair of diametric cylindrical magnets. This system yields\na fascinating 1D camelback potential along the longitudinal axis which is one\nof the elementary model potentials of interest in physics. This potential can\nbe tailored by controlling the magnet length/radius aspect ratio. We developed\ntheoretical models and verify them with experiments using graphite rods. We\nshow that, in general, a camelback field or potential profile exists in between\na pair of parallel linear dipole distribution. By exploiting this potential, we\ndemonstrate a unique and simple technique to determine the magnetic\nsusceptibility of the rod. This system could be further utilized as a platform\nfor custom-designed 1D potential, a highly sensitive force-distance transducer\nor a trap for semiconductor nanowires."
    },
    {
        "anchor": "From Silver Nanoparticles to Thin Films: Evolution of Microstructure and\n  Electrical Conduction: Silver nanoparticles embedded in a dielectric matrix are investigated for\ntheir potential as broadband-absorbing optical sensor materials. This\ncontribution focuses on the electrical properties of silver nanoparticles at\nvarious morphological stages. The electrical current through thin films,\nconsisting of silver nanoparticles, was characterized as a function of film\nthickness. Three distinct conductivity zones were observed. Two relatively flat\nzones (\"dielectric\" for very thin films and \"metallic\" for films thicker than\n300 - 400 {\\AA}) are separated by a sharp transition zone where percolation\ndominates. The dielectric zone is characterized by isolated particle islands\nwith the electrical conduction dominated by a thermally activated tunneling\nprocess. The transition zone is dominated by interconnected silver nanoclusters\n- a small increase of the film thickness results in a large increase of the\nelectrical conductivity. The metallic conductivity zone dominates for\nthicknesses above 300 - 400 {\\AA}.",
        "positive": "High Temperature Ferromagnetism in GaAs-based Heterostructures with Mn\n  Delta Doping: We show that suitably-designed magnetic semiconductor heterostructures\nconsisting of Mn delta-doped GaAs and p-type AlGaAs layers, in which the\nlocally high concentration of magnetic moments of Mn atoms are controllably\noverlapped with the 2-dimensional hole gas wavefunction, realized remarkably\nhigh ferromagnetic transition temperatures (TC). Significant reduction of\ncompensative Mn interstitials by varying the growth sequence of the structures\nfollowed by low temperature annealing led to high TC up to 250 K. The\nheterostructure with high TC exhibited peculiar anomalous Hall effect behavior,\nwhose sign depends on temperature."
    },
    {
        "anchor": "Magnetic field and temperature sensing with atomic-scale spin defects in\n  silicon carbide: Quantum systems can provide outstanding performance in various sensing\napplications, ranging from bioscience to nanotechnology. Atomic-scale defects\nin silicon carbide are very attractive in this respect because of the\ntechnological advantages of this material and favorable optical and radio\nfrequency spectral ranges to control these defects. We identified several,\nseparately addressable spin-3/2 centers in the same silicon carbide crystal,\nwhich are immune to nonaxial strain fluctuations. Some of them are\ncharacterized by nearly temperature independent axial crystal fields, making\nthese centers very attractive for vector magnetometry. Contrarily, the\nzero-field splitting of another center exhibits a giant thermal shift of -1.1\nMHz/K at room temperature, which can be used for thermometry applications. We\nalso discuss a synchronized composite clock exploiting spin centers with\ndifferent thermal response.",
        "positive": "Evidence for the role of the magnon energy relaxation length in the Spin\n  Seebeck Effect: Temperature-dependent spin-Seebeck effect data on Pt|YIG\n(Y$_3$Fe$_5$O$_{12}$)|GGG (Gd$_3$Ga$_5$O$_{12}$) are reported for YIG films of\nvarious thicknesses. The effect is reported as a spin-Seebeck resistivity\n(SSR), the inverse spin-Hall field divided by the heat flux, to circumvent\nuncertainties about temperature gradients inside the films. The SSR is a\nnon-monotonic function of YIG thickness. A diffusive model for magnon transport\ndemonstrates how these data give evidence for the existence of two distinct\nlength scales in thermal spin transport, a spin diffusion length and a magnon\nenergy relaxation length."
    },
    {
        "anchor": "Organic crystalline polymers: structural properties and way to synthesis\n  under high pressure: We consider different structures, which can be obtained by polymerization of\naromatic organic molecules under high pressures. These 2D and 3D covalently\nbonded organic polymers and their functionalization can pave the way to\nproduction of energy storage and conversion devices. High-pressure synthesis\nmight serve as a useful hint for production of these structures and their\nfunctionalized analogs by means of wet chemical synthesis.",
        "positive": "Hafnia for analog memristor: Influence of stoichiometry and crystalline\n  structure: The highly non-linear switching behavior of hafnia memristor actually hinders\nits wide application in neuromorphic computing. Theoretical understanding into\nits switching mechanism has been focused on the processes of conductive\nfilament generation and rupture, but possible phase transition and\ncrystallization around the region of conductive filaments (CFs) due to the\nvariation of O content have been paid less attention to. In this paper,\nHfO$\\mathrm{_x}$ structural models covering the full stoichiometries from Hf to\nHfO$\\mathrm{_2}$ were established, and the crystal structure evolution during\nthe reduction process of hafnia was obtained through first-principles\ncalculation. The electronic structures and O vacancy migration characteristics\nof these structures were analyzed. A criterion was prescribed to predict the\nmode of abrupt binary switching or gradual conductance modulation according to\nthe structure evolution of the CFs. In particular, factors that influence the\nmerging of tiny conductive channels into strong filaments are intensively\ndiscussed, including the anisotropy of O vacancy migration and the size effect.\nThe feasibility of Mg doping to achieve robust gradual switching is discussed."
    },
    {
        "anchor": "Aerodynamic Stability and the Growth of Triangular Snow Crystals: We describe laboratory-grown snow crystals that exhibit a triangular,\nplate-like morphology, and we show that the occurrence of these crystals is\nmuch more frequent than one would expect from random growth perturbations of\nthe more-typical hexagonal forms. We then describe an aerodynamic model that\nexplains the formation of these crystals. A single growth perturbation on one\nfacet of a hexagonal plate leads to air flow around the crystal that promotes\nthe growth of alternating facets. Aerodynamic effects thus produce a weak\ngrowth instability that can cause hexagonal plates to develop into triangular\nplates. This mechanism solves a very old puzzle, as observers have been\ndocumenting the unexplained appearance of triangular snow crystals in nature\nfor nearly two centuries.",
        "positive": "Structural, Vibrational, Elastic and Topological Properties of PaN Under\n  Pressure: Electronic, structural, vibrational and elastic properties of PaN have been\nstudied both at ambient and high pressures, using first principles methods with\nseveral commonly used parameterizations of the exchange-correlation energy. The\ngeneralized gradient approximation (GGA) reproduces the ground state properties\nsatisfactorily. Under pressure PaN is found to undergo a structural transition\nfrom NaCl to the R-3m structure near 58 GPa. The high pressure behavior of the\nacoustic phonon branch along the (1,0,0) and (1,1,0) directions, and the C44\nelastic constant are anomalous, which signals the structural transition. With\nGGA exchange-correlation, a topological transition in the charge density occurs\nnear the structural transition which may be regarded as a quantum phase\ntransition, where the order parameter obeys a mean field scaling law. However,\nthe topological transition is absent when other exchange-correlation\nfunctionals are invoked (local density approximation (LDA) and hybrid\nfunctional). Therefore, this constitutes an example of GGA and LDA leading to\nqualitatively different predictions, and it is of great interest to examine\nexperimentally whether this topological transition occurs."
    },
    {
        "anchor": "Nonlinear electrochemical relaxation around conductors: We analyze the simplest problem of electrochemical relaxation in more than\none dimension - the response of an uncharged, ideally polarizable metallic\nsphere (or cylinder) in a symmetric, binary electrolyte to a uniform electric\nfield. In order to go beyond the circuit approximation for thin double layers,\nour analysis is based on the Poisson-Nernst-Planck (PNP) equations of dilute\nsolution theory. Unlike most previous studies, however, we focus on the\nnonlinear regime, where the applied voltage across the conductor is larger than\nthe thermal voltage. In such strong electric fields, the classical model\npredicts that the double layer adsorbs enough ions to produce bulk\nconcentration gradients and surface conduction. Our analysis begins with a\ngeneral derivation of surface conservation laws in the thin double-layer limit,\nwhich provide effective boundary conditions on the quasi-neutral bulk. We solve\nthe resulting nonlinear partial differential equations numerically for strong\nfields and also perform a time-dependent asymptotic analysis for weaker fields,\nwhere bulk diffusion and surface conduction arise as first-order corrections.\nWe also derive various dimensionless parameters comparing surface to bulk\ntransport processes, which generalize the Bikerman-Dukhin number. Our results\nhave basic relevance for double-layer charging dynamics and nonlinear\nelectrokinetics in the ubiquitous PNP approximation.",
        "positive": "Hot electron diffusion, microwave noise, and piezoresistivity in Si from\n  first principles: Ab-initio calculations of charge transport properties in materials without\nadjustable parameters have provided microscopic insights into electron-phonon\ninteractions which govern charge transport properties. Other transport\nproperties such as the diffusion coefficient provide additional microscopic\ninformation and are readily accessible experimentally, but few ab-initio\ncalculations of these properties have been performed. Here, we report\nfirst-principles calculations of the hot electron diffusion coefficient in Si\nand its dependence on electric field over temperatures from 77 -- 300 K. While\nqualitative agreement in trends such as anisotropy at high electric fields is\nobtained, the quantitative agreement that is routinely achieved for low-field\nmobility is lacking. We examine whether the discrepancy can be attributed to an\ninaccurate description of f-type intervalley scattering by computing the\nmicrowave-frequency noise spectrum and piezoresistivity. These calculations\nindicate that any error in the strength of f-type scattering is insufficient to\nexplain the diffusion coefficient discrepancies. Our findings suggest that the\nmeasured diffusion coefficient is influenced by factors such as space charge\neffects which are not included in ab-initio calculations, impacting the\ninterpretation of this property in terms of charge transport processes."
    },
    {
        "anchor": "Electron-ion coupling in semiconductors beyond Fermi's golden rule: In the present work, a theoretical study of electron-phonon (electron-ion)\ncoupling rates in semiconductors driven out of equilibrium is performed.\nTransient change of optical coefficients reflects the band gap shrinkage in\ncovalently bonded materials, and thus, the heating of atomic lattice. Utilizing\nthis dependence, we test various models of electron-ion coupling. The\nsimulation technique is based on tight-binding molecular dynamics. Our\nsimulations with the dedicated hybrid approach (XTANT) indicate that the widely\nused Fermi's golden rule can break down describing material excitation on\nfemtosecond time scales. In contrast, dynamical coupling proposed in this work\nyields a reasonably good agreement of simulation results with available\nexperimental data.",
        "positive": "Photoemission studies of the annealing induced modifications of\n  (Ga,Mn)As: Using angle resolved photoemission we have investigated annealing-induced\nchanges in Ga(1-x)Mn(x)As with x = 0.05. We find that the position of the Fermi\nenergy is a function of annealing time and temperature. It is also established\nthat the Curie temperature is strongly correlated to the separation between the\nFermi level and the valence band maximum. Valence band photoemission shows that\nthe Mn3d spectrum is modified by the annealing treatments"
    },
    {
        "anchor": "On stress concentration in nanotwinned metals: In their papers, Lu et al. analysed experimental data from in-situ\ntransmission electron microscopy (TEM) and concluded that local stress\nconcentration at grain boundary-twin boundary (GB-TB) intersections in\nnanotwinned (nt-) metals increases as the TB thicknesses is reduced (below\n${\\lambda}$ $\\leq$ 18 nm). However, here, by analysing the raw experimental\ndata in Lu et al. together with finite element simulations and dimensional\nanalysis, we show that the measurement of local stress concentration in a\nnt-material is highly sensitive to the adopted averaging box size due to the\nhigh stress gradient near GB-TB intersections as well as to the TB location in\nthe nt-grain. By careful analysis of the raw data, a completely reverse trend,\nwhich is consistent with well-established laws of continuum mechanics, can be\ncaptured.",
        "positive": "Optimizing Floquet engineering for non-equilibrium steady states with\n  gradient-based methods: Non-equilibrium steady states are created when a periodically driven quantum\nsystem is also incoherently interacting with an environment -- as it is the\ncase in most realistic situations. The notion of Floquet engineering refers to\nthe manipulation of the properties of systems under periodic perturbations.\nAlthough it more frequently refers to the coherent states of isolated systems\n(or to the transient phase for states that are weakly coupled to the\nenvironment), it may sometimes be of more interest to consider the final steady\nstates that are reached after decoherence and dissipation take place. In this\nwork, we propose a computational method to find the multicolor periodic\nperturbations that lead to the final steady states that are optimal with\nrespect to a given predefined metric, such as for example the maximization of\nthe temporal average value of some observable. We exemplify the concept using a\nsimple model for the nitrogen-vacancy center in diamond: the goal in this case\nis to find the driving periodic magnetic field that maximizes a time-averaged\nspin component. We show that, for example, this technique permits to prepare\nstates whose spin values are forbidden in thermal equilibrium at any\ntemperature."
    },
    {
        "anchor": "Development of Interatomic Potential for Al-Tb Alloy by Deep Neural\n  Network Learning Method: An interatomic potential for Al-Tb alloy around the composition of Al90Tb10\nwas developed using the deep neural network (DNN) learning method. The atomic\nconfigurations and the corresponding total potential energies and forces on\neach atom obtained from ab initio molecular dynamics (AIMD) simulations are\ncollected to train a DNN model to construct the interatomic potential for Al-Tb\nalloy. We show the obtained DNN model can well reproduce the energies and\nforces calculated by AIMD. Molecular dynamics (MD) simulations using the DNN\ninteratomic potential also accurately describe the structural properties of\nAl90Tb10 liquid, such as the partial pair correlation functions (PPCFs) and the\nbond angle distributions, in comparison with the results from AIMD.\nFurthermore, the developed DNN interatomic potential predicts the formation\nenergies of crystalline phases of Al-Tb system with the accuracy comparable to\nab initio calculations. The structure factor of Al90Tb10 metallic glass\nobtained by MD simulation using the developed DNN interatomic potential is also\nin good agreement with the experimental X-ray diffraction data.",
        "positive": "Self-assembly of the chiral donor-acceptor molecule DCzDCN on Cu(100): Donor-acceptor (D-A) structured molecules are essential components in organic\nelectronics. The respective molecular structure of these molecules and their\nsynthesis are primarily determined by the intended area of application.\nTypically, D-A molecules promote charge separation and transport in organic\nphotovoltaics (OPV) or organic field-effect transistors (OFET). D-A molecules\nshowing a larger twist angle between D and A units are, e.g., extremely\nimportant for the development of high internal quantum efficiency in organic\nlight-emitting diodes (OLEDs). A prototypical molecule of this D-A type is\nDCzDCN (5-(4,6-diphenyl-1,3,5-triazin-2-yl)benzene-1,3-dinitrile). In most\ncases, these molecules are only investigated regarding their electronic and\nstructural interaction in bulk aggregates but not in ultra-thin films supported\nby a metallic substrate. Here, we present growth and electronic structure\nstudies of DCzDCN on a Cu(100) surface. In a complementary approach, through\nthe use of Scanning Tunneling Microscopy and Spectroscopy (STM and STS), we\nwere able to view both the adsorption geometry and the local electronic states\nof the adsorbed molecules in direct comparison with the integral electronic\nstructure of the DCzDCN/CU(100) interface using Ultraviolet and Inverse\nPhotoemission Spectroscopy (UPS and IPS). The orientation of the molecules with\nthe donor part towards the substrate results in a chiral resolution at the\ninterface due to the molecular as well as the substrate symmetry and additional\nstrong molecular electrostatic forces. Thus, the formation of various\nbulk-unlike homochiral structures and the appearance of hybrid interface states\n(HIS) modifies the molecular electronic properties of the DCzDCN/Cu(100) system\nsignificantly compared to that of a single DCzDCN molecule. This may be not\nonly useful for optoelectronic applications but also in organic spintronics."
    },
    {
        "anchor": "Decoherence processes of a quantum two-level system coupled to a\n  fermionic environment: We study decoherence processes of an S = 1/2 localized spin coupled to\nconduction band electrons in a metal or a semiconductor via an Ising-like\ninteraction. We derive master equations for the density matrix of the localized\nspin, by tracing out all degrees of freedom in the conduction electron system\nbased on the linked-cluster-expansion technique. It is found that the\ndecoherence occurs more rapidly for the metallic case than for semiconducting\ncase.",
        "positive": "Strong, anisotropic anomalous Hall effect and spin Hall effect in chiral\n  antiferromagnetic compounds Mn$_3X$ ($X$ = Ge, Sn, Ga, Ir, Rh and Pt): We have carried out a comprehensive study of the intrinsic anomalous Hall\neffect and spin Hall effect of several chiral antiferromagnetic compounds,\nMn$_3X$ ($X$ = Ge, Sn, Ga, Ir, Rh and Pt) by $ab~initio$ band structure and\nBerry phase calculations. These studies reveal large and anisotropic values of\nboth the intrinsic anomalous Hall effect and spin Hall effect. The Mn$_3X$\nmaterials exhibit a non-collinear antiferromagnetic order which, to avoid\ngeometrical frustration, forms planes of Mn moments that are arranged in a\nKagome-type lattice. With respect to these Kagome planes, we find that both the\nanomalous Hall conductivity (AHC) and the spin Hall conductivity (SHC) are\nquite anisotropic for any of these materials. Based on our calculations, we\npropose how to maximize AHC and SHC for different materials. The band\nstructures and corresponding electron filling, that we show are essential to\ndetermine the AHC and SHC, are compared for these different compounds. We point\nout that Mn$_3$Ga shows a large SHC of about 600 $(\\hbar/e)(\\Omega\\cdot\ncm)^{-1}$. Our work provides insights into the realization of strong anomalous\nHall effects and spin Hall effects in chiral antiferromagetic materials."
    },
    {
        "anchor": "Probing temperature-induced phase transitions at individual\n  ferroelectric domain walls: Ferroelectric domain walls have emerged as one of the most fascinating\nobjects in condensed matter physics due to the broad variability of functional\nbehaviors they exhibit. However, the vast majority of domain walls studies have\nbeen focused on bias-induced dynamics and transport behaviors. Here, we\nintroduce the scanning probe microscopy approach based on piezoresponse force\nmicroscopy (PFM) with a dynamically heated probe, combining local heating and\nlocal biasing of the material. This approach is used to explore the thermal\npolarization dynamics in soft Sn2P2S6 ferroelectrics, and allows for the\nexploration of phase transitions at individual domain walls. The strong and\nweak modulation regimes for the thermal PFM are introduced. The future\npotential applications of heated probe approach for functional SPM measurements\nincluding piezoelectric, elastic, microwave, and transport measurements are\ndiscussed.",
        "positive": "Substrate screening effects on the quasiparticle band gap and defect\n  charge transition levels in MoS$_2$: Monolayer MoS$_2$ has emerged as an interesting material for nanoelectronic\nand optoelectronic devices. The effect of substrate screening and defects on\nthe electronic structure of MoS$_2$ are important considerations in the design\nof such devices. Here, we present ab initio density functional theory (DFT) and\nGW calculations to study the effect of substrate screening on the quasiparticle\nband gap and defect charge transition levels (CTLs) in monolayer MoS$_2$. We\nfind a giant renormalization to the free-standing quasiparticle band gap by 350\nmeV and 530 meV in the presence of graphene and graphite as substrates,\nrespectively. Our results are corroborated by recent experimental measurements\non these systems using scanning tunneling spectroscopy and photoluminescence\nexcitation spectroscopy. Sulfur vacancies are the most abundant native defects\nfound in MoS$_2$. We study the CTLs of these vacancies in MoS$_2$ using the\nDFT+GW formalism. We find (+1/0) and (0/-1) CTLs appear in the pristine band\ngap of MoS$_2$. Substrate screening results in renormalization of the (0/-1)\nlevel, with respect to the valence band maximum (VBM), by the same amount as\nthe gap. This results in the pinning of the (0/-1) level about $\\sim$500 meV\nbelow the conduction band minimum for the free-standing case as well as in the\npresence of substrates. The (+1/0) level, on the other hand, lies less than 100\nmeV above the VBM for all the cases."
    },
    {
        "anchor": "On the physical mechanisms of relaxation time distribution in disordered\n  dielectrics: The distribution function of relaxation times in disordered dielectrics has\nbeen calculated in the random field theory framework. For this purpose, we\nfirst consider the dynamics of single two-orientable impurity electric dipole\nin a random electric field $E$ created by the rest of impurities in disordered\nferroelectric. This dynamics is conveniently described by Langevin equation.\nRelaxation time $\\tau $ is then a reciprocal probability (calculated on the\nbase of Fokker-Planck equation) of the dipole transition through barrier in a\ndouble-well potential (corresponding to two possible dipole orientations),\ndistorted by a random fields. The obtained dependence $\\tau (E)$ made it\npossible to obtain the expression for relaxation times distribution function\n$F(\\tau)$(via random fields distribution function $f(E)$. Latter function has\nbeen calculated self-consistently in the random field theory framework.\nNonlinear random field contribution and effects of spatial correlations between\nimpurities have also been taken into account. It was shown that nonlinear\ncontribution of random field gives asymmetric shape of $F(\\tau)$, while in\nlinear case it is symmetric. Comparison of calculated $F(\\tau)$ curves with\nthose extracted from empirical Cole-Cole (CC), Davidson-Cole (DC),\nKohlrausch-William-Watts (KWW) and Havriliak-Negami (HN) functions had shown,\nthat they correspond to mixed ferro-glass phase with coexistence of short and\nlong-range order. Different forms of $F(\\tau)$ are determined by linear (CC) or\nnonlinear (DC, KWW, HN) contributions of random field.",
        "positive": "ALD grown zinc oxide with controllable electrical properties: The paper presents results for zinc oxide films grown at low temperature\nregime by Atomic Layer Deposition (ALD). We discuss electrical properties of\nsuch films and show that low temperature deposition results in oxygen-rich ZnO\nlayers in which free carrier concentration is very low. For optimized ALD\nprocess it can reach the level of 10^15 cm-3, while mobility of electrons is\nbetween 20 and 50 cm2/Vs. Electrical parameters of ZnO films deposited by ALD\nat low temperature regime are appropriate for constructing of the ZnO-based p-n\nand Schottky junctions. We demonstrate that such junctions are characterized by\nthe rectification ratio high enough to fulfill requirements of 3D memories and\nare deposited at temperature 100degC which makes them appropriate for\ndeposition on organic substrates."
    },
    {
        "anchor": "Experimental demonstration of hybrid improper ferroelectricity and\n  presence of abundant charged walls in (Ca,Sr)$_{3}$Ti$_{2}$O$_{7}$ crystals: Standing on successful first principles predictions for new functional\nferroelectric materials, a number of new ferroelectrics have been\nexperimentally discovered. Utilizing trilinear coupling of two types of\noctahedron rotations, hybrid improper ferroelectricity has been theoretically\npredicted in ordered perovskites and the Ruddlesden-Popper compounds\n(Ca$_{3}$Ti$_{2}$O$_{7}$, Ca$_{3}$Mn$_{2}$O$_{7}$, and\n(Ca/Sr/Ba)$_{3}$(Sn/Zr/Ge)$_{2}$O$_{7}$). However, the ferroelectricity of\nthese compounds has never been experimentally confirmed and even their polar\nnature has been under debate. Here we provide the first experimental\ndemonstration of room-temperature switchable polarization in the bulk crystals\nof Ca$_{3}$Ti$_{2}$O$_{7}$ as well as Sr-doped Ca$_{3}$Ti$_{2}$O$_{7}$. In\naddition, (Ca,Sr)$_{3}$Ti$_{2}$O$_{7}$ is found to exhibit an intriguing\nferroelectric domain structure resulting from orthorhombic twins and\n(switchable) planar polarization. The planar domain structure accompanies\nabundant charged domain walls with conducting head-to-head and insulating\ntail-to-tail configurations, which exhibit two-order-of-magnitude conduction\ndifference. These discoveries provide new research opportunities not only on\nnew stable ferroelectrics of Ruddlesden-Popper compounds, but also on\nmeandering conducting domain walls formed by planar polarization.",
        "positive": "Thermal Conduction in Single-Layer Black Phosphorus: Highly Anisotropic?: The single-layer black phosphorus is characteristic for its puckered\nstructure, which has leaded to highly anisotropy in its optical, electronic,\nand mechanical properties. We report, using the non-equilibrium Green's\nfunction approach and the first-principles method, that the anisotropy in the\nthermal conduction is very weak in the single-layer black phosphorus -- the\ndifference between two in-plane directions is less than 4%. Our phonon\ncalculations disclose that the two in-plane acoustic phonon branches have lower\ngroup velocities in the direction perpendicular to the pucker, as the black\nphosphorus is softer in this direction, leading to a weakening effect for the\nthermal conductance in the perpendicular direction. However, the out-of-plane\nacoustic phonon branch behaviors abnormally; i.e., the group velocity of this\nphonon branch is higher in the perpendicular direction, although the\nsingle-layer black phosphorus is softer in this direction. The abnormal\nbehavior of the out-of-plane phonon branch is closely related to the highly\nanisotropic Poisson's ratio in the single-layer black phosphorus. As a result\nof the counteraction between the in-plane phonon modes and the out-of-plane\nphonon mode, the thermal conductance in the perpendicular direction is weaker\nthan the parallel direction, but the anisotropy is pretty small."
    },
    {
        "anchor": "Phonon chirality manipulation mechanism in TMD interlayer-sliding\n  ferroelectrics: As an ideal platform, both the theoretical prediction and first experimental\nverification of chiral phonons are based on transition-metal dichalcogenide\nmaterials. The manipulation of phonon chirality in these materials will have a\nprofound impact on the study of chiral phonons. In this work, we utilize the\nsliding ferroelectric mechanism to study the phonon chirality manipulation\nmechanism in transition-metal dichalcogenide materials. Based on\nfirst-principles calculations, we study the different effects of interlayer\nsliding on the phonon properties in bilayer and four-layer MoS$_2$ sliding\nferroelectrics. We find that sliding can regulate phonon chirality and Berry\ncurvature, which further affects the phonon angular momentum and magnetization\nunder a temperature gradient and the phonon Hall effect under a magnetic field.\nOur work connects two emerging fields and opens up a new route to manipulate\nphonon chirality in transition-metal dichalcogenide materials through the\nsliding ferroelectric mechanism.",
        "positive": "Perpendicular magnetic anisotropy and half metallicity in Cr2Ge2Te6\n  nanoribbons: The Cr2Ge2Te6 (CGT) compound is an intrinsic ferromagnetic material with a\nvan der Waals layered structure that shows great promise in spintronics\napplications. In this work, we investigated the edge effect in the formation of\nCGT nanoribbons with different terminations as well as the change in electronic\nand magnetic properties considering spin-orbit effects on the calculations. We\nstudied the thermodynamic stability of the nanoribbon employing the surface\nformation energy formalism. According to the calculations, in regions of\nGe-rich, Te-rich, and Ge-poor, Te-poor of chemical potential the nanoribbon\nwith TeCr edges is the most stable structure, while in the regions of Ge-rich,\nTe-poor and Ge-poor, Te-poor the nanoribbon with TeCr edges and Te vacancies is\nthe most stable structure. Furthermore, calculations show that the nanoribbon\nis ferromagnetic with half metal characteristics."
    },
    {
        "anchor": "Unveiling the nucleation and growth of Zr oxide precipitates of\n  internally oxidized Nb3Sn superconductors: We report on atomic-scale analyses of nucleation and growth of Zr oxide\nprecipitates and the microstructural evolution of internally oxidized Nb3Sn\nwires for high-field superconducting magnet applications, utilizing atom probe\ntomography (APT), transmission electron microscopy (TEM), and first-principles\ncalculations. APT analyses reveal that prior to interfacial reactions at\nNb/Nb3Sn interfaces, Zr atoms in an unreacted Nb-1Zr-4Ta (at.%) alloy form\nclusters with O atoms owing to their high affinity for oxygen and are\nsegregated at grain boundaries (GBs) in the Nb grains. Then, nucleation of Zr\noxide precipitates occurs in Nb3Sn and at Nb3Sn/Nb interfaces, driven by the\nsmall solubility of Zr and O in Nb3Sn compared to Nb. Quantitative APT and TEM\nanalyses of Zr oxide precipitates in Nb3Sn layers demonstrate the nucleation,\ngrowth, and coarsening processes of Zr oxide precipitates in Nb3Sn layers. A\nhigh number density of Zr oxide nanoprecipitates is observed in the Nb3Sn\nlayers, ~10^23 per m^3, with a mean precipitate diam. <10 nm at 625 oC and 700\noC, which provide pinning centers for grain refinement of Nb3Sn, <100 nm diam.,\nand serve as pinning sites for fluxons. First-principles calculations and\nclassical nucleation theory are employed to describe the nucleation of Zr oxide\nprecipitates in Nb3Sn: energy barriers and the critical radius for nucleation\nof Zr oxide precipitates in Nb3Sn. Our research yields the kinetic pathways for\nnucleation and growth of Zr oxide precipitates and the microstructural\nevolution of Nb3Sn layers, which helps to improve the fabrication process of\ninternally oxidized Nb3Sn wires for high-field superconducting magnets.",
        "positive": "Charged grain boundaries reduce the open circuit voltage of\n  polycrystalline solar cells--An analytical description: Analytic expressions are presented for the dark current-voltage relation\n$J(V)$ of a $pn^+$ junction with positively charged columnar grain boundaries\nwith high defect density. These expressions apply to non-depleted grains with\nsufficiently high bulk hole mobilities. The accuracy of the formulas is\nverified by direct comparison to numerical simulations. Numerical simulations\nfurther show that the dark $J(V)$ can be used to determine the open circuit\npotential $V_{\\rm oc}$ of an illuminated junction for a given short-circuit\ncurrent density $J_{\\rm sc}$ . A precise relation between the grain boundary\nproperties and $V_{\\rm oc}$ is provided, advancing the understanding of the\ninfluence of grain boundaries on the efficiency of thin film polycrystalline\nphotovoltaics like CdTe and $\\mathrm{Cu(In,Ga)Se_2}$."
    },
    {
        "anchor": "Critical influence of target-to-substrate distance on conductive\n  properties of LaGaO3/SrTiO3 interfaces deposited at 10-1 mbar oxygen pressure: We investigate pulsed laser deposition of LaGaO3/SrTiO3 at 10-1 mbar oxygen\nbackground pressure, demonstrating the critical effect of the\ntarget-to-substrate distance, dTS, on the interface sheet resistance, Rs. The\ninterface turns from insulating to metallic by progressively decreasing dTS.\nThe analysis of the LaGaO3 plume evidences the important role of the plume\npropagation dynamics on the interface properties. These results demonstrate the\ngrowth of conducting interfaces at an oxygen pressure of 10-1 mbar, an\nexperimental condition where a well-oxygenated heterostructures with a reduced\ncontent of oxygen defects is expected.",
        "positive": "Landau quantization in tilted Weyl semimetals with broken symmetry: Broken symmetry and tilting effects are ubiquitous in Weyl semimetals (WSMs).\nTherefore, it is crucial to understand their impacts on the materials'\nelectronic and optical properties. Here, using a realistic four-band model for\nWSMs that incorporates both the symmetry breaking and tilting effects, we study\nits Landau quantization and the associated magneto-absorption spectrum. We show\nthat the Landau levels in tilted Weyl bands can be obtained by considering a\nnon-tilt Hamiltonian through Lorentz boost. However, broken symmetry effects\ncan generate an additional term in the Hamiltonian, which equivalently leads to\nband reconstruction. Our work provides a more realistic view of the magnetic\nfield response of WSMs that shall be taken into account in relevant future\ndevice applications."
    },
    {
        "anchor": "Chiral honeycomb superstructure, parquet nesting, and Dirac cone\n  formation in Cu-intercalated 2H-TaSe2: Powered by effective parquet nesting a commensurate chiral honeycomb\nsuperstructure in a trigonally packed transition metal dichalcogenide TaSe$_2$\nresults in a Dirac cone anomaly in one-particle excitation spectrum. However,\nthe formation of the well defined Dirac point seems to be hindered by effective\nscattering on 2D plasmons.",
        "positive": "Li-ion diffusion in single crystal LiFePO$_4$ measured by muon spin\n  spectroscopy: Muon spin spectroscopy ($\\mu^+$SR) is now an established method to measure\natomic scale diffusion coefficients of ions in oxides. This is achieved via the\nion hopping rate, which causes periodic change in the local magnetic field at\nthe muon site(s). We present here the first systematic study on a single\ncrystalline sample. The highly anisotropic diffusion of Li-ions in the battery\ncathode material LiFePO$_4$, combined with the extensive investigation of this\nmaterial with $\\mu^+$SR and other techniques make it a perfect model compound\nfor this study. With this experiment we can confirm that Li diffusion in the\nbulk LiFePO$_4$ is measurable with $\\mu^+$SR. Hence, surface/interface effects,\nwhich might play a crucial role in case of powders/nano crystals, are less\nsignificant for macroscopic single crystals where bulk diffusion is in fact\npresent. We observe that the internal magnetic field fluctuations caused by the\ndiffusing Li-ions are different depending on the crystal orientation. This is\nnot obviously expected based on theoretical considerations. Such fluctuation\nrates were used to estimate the diffusion coefficient, which agrees well with\nvalues estimated by first principle calculations considering anisotropic\ndiffusion."
    },
    {
        "anchor": "Analytic description of anomalous diffusion in heterogeneous\n  environments: Fokker-Planck equation without fractional derivatives: We present a model of diffusion in heterogeneous environment, which\nqualitatively reflects the transport properties of a polymeric membrane with\ncarbon nanotubes. We derived Fokker-Planck equation from system of stochastic\nequations, responding diffusion regime in polymer and ballistic regime in\nnanotube areas. We show how probability density function is changed in presence\nof nanotube areas. Hereupon nonlinear time dependence of mean square\ndisplacement is observed, that indicates anomalous diffusion regime. Thus, the\nmodel explains mechanism of appearance of anomalous diffusion for\ndiffusion-ballistic regime. Our approach does not suppose any type of\ndistributions and using fractional differentiate apparatus.",
        "positive": "Tuning the Electronic and Magnetic Properties of Double Transition Metal\n  MCrCT$_2$ (M = Ti, Mo) Janus MXenes for Enhanced Spintronics and\n  Nanoelectronics: Janus MXenes, a new category of two-dimensional (2D) materials, shows\npromising potential for advances in optoelectronics, spintronics and\nnanoelectronics. Our theoretical investigations not only provide interesting\ninsights but also highlight the promise of Janus MCrCT$_2$ (M = Ti, Mo; T = O,\nF, OH) MXenes for future spintronic applications and highlight the need for\ntheir synthesis. Electronic structure analysis shows different metallic and\nsemi-metallic properties: MoCrCF$_2$ exhibits metallic properties,\nTiCrC(OH)$_2$ and MoCrCO$_2$ exhibit near semi-metallicity with spin\npolarization values of 61\\% and 86\\%, respectively, while TiCrCO$_2$ and\nTiCrCF$_2$ are completely half-metallic with 100\\% spin polarization at the\nFermi level. All studied Janus MXenes exhibit intrinsic ferromagnetism, which\nis mainly attributed to the chromium (Cr) atoms, as shown by the spin density\ndifference plots. Among them, the TiCrCO$_2$ monolayer stands out with the\nhighest exchange constant and ferromagnetic transition temperature (T$_c$).\nNotably, the O-terminated Janus MXenes exhibit weak perpendicular magnetic\nanisotropy, in contrast to the in-plane anisotropy observed for F and\nOH-terminated MXenes, making them particularly interesting for future\nspintronic applications which we further demonstrate with micromagnetic\nsimulation which reveal distinct current-induced switching behaviors in these\nJanus MXenes with different surface terminations."
    },
    {
        "anchor": "Anomalous Hall resistance in Ge:Mn systems with low Mn concentrations: Taking Mn doped Germanium as an example, we evoke the consideration of a\ntwo-band-like conduction in diluted ferromagnetic semiconductor (FMS). The main\nargument for claiming Ge:Mn as a FMS is the occurrence of the anomalous Hall\neffect (AHE). Usually, the reported AHE (1) is observable at temperatures above\n10 K, (2) exhibits no hysteresis, and (3) changes the sign of slope. We\nobserved a similar Hall resistance in Mn implanted Ge with the Mn concentration\nas low as 0.004%. We show that the puzzling AHE features can be explained by\nconsidering a two-band-like conduction in Ge:Mn.",
        "positive": "Spontaneous non-stoichiometry and ordering of metal vacancies in\n  degenerate insulators: We point to a class of materials representing an exception to the Daltonian\nview that compounds maintain integer stoichiometry at low temperatures, because\nforming stoichiometry-violating defects cost energy. We show that carriers in\nthe conduction band (CB) of degenerate insulators in Ca-Al-O, Ag-Al-O, or\nBa-Nb-O systems can cause a self-regulating instability, whereby cation\nvacancies form exothermically because a fraction of the free carriers in the CB\ndecay into the hole states formed by such vacancies, and this negative\nelectron-hole recombination energy offsets the positive energy associated with\nvacancy bond breaking. This Fermi level-induced spontaneous non-stoichiometry\ncan lead to the formation of crystallographically ordered vacancy compounds\n(OVCs), explaining the previously peculiar occurrence of unusual atomic\nsequences such as BalNbmOn with l:m:n ratios of 1:2:6, 3:5:15, or 9:10:30. This\nwork has general ramifications as the degenerate insulators have found growing\ninterests in many fields ranging from transparent conductors to electrides that\nare electron donating promotors for catalyst."
    },
    {
        "anchor": "Enhancement of Ion Diffusion by Targeted Phonon Excitation: Ion diffusion is important in a variety of applications, yet fundamental\nunderstanding of the diffusive process in solids is still missing, especially\nconsidering the interaction of lattice vibrations (phonons) and the mobile\nspecies. In this work, we introduce two formalisms that determine the\nindividual contributions of normal modes of vibration (phonons) to the\ndiffusion of ions through a solid, based on (i) Nudged Elastic Band (NEB)\ncalculations and (ii) molecular dynamics (MD) simulations. The results for a\nmodel ion conductor of $\\rm{Ge}$-substituted $\\rm{Li_3PO_4}$\n($\\rm{Li_{3.042}Ge_{0.042}P_{0.958}O_4}$) revealed that more than 87% of the\n$\\rm{Li^+}$ ion diffusion in the lattice originated from a subset of less than\n10% of the vibrational modes with frequencies between 8 and 20 THz. By\ndeliberately exciting a small targeted subset of these contributing modes (less\nthan 1%) to a higher temperature and still keeping the lattice at low\ntemperature, we observed an increase in diffusivity by several orders of\nmagnitude, consistent with what would be observed if the entire material (i.e.,\nall modes) were excited to the same high temperature. This observation suggests\nthat an entire material need not be heated to elevated temperatures to increase\ndiffusivity, but instead only the modes that contribute to diffusion, or more\ngenerally a reaction/transition pathway, need to be excited to elevated\ntemperatures. This new understanding identifies new avenues for increasing\ndiffusivity by engineering the vibrations in a material, and/or increasing\ndiffusivity by external stimuli/excitation of phonons (e.g., via photons or\nother interactions) without necessarily changing the compound chemistry.",
        "positive": "Third harmonic generation on exciton-polaritons in bulk semiconductors\n  subject to a magnetic field: We report on a comprehensive experimental and theoretical study of optical\nthird harmonic generation (THG) on the exciton-polariton resonances in the\nzinc-blende semiconductors GaAs, CdTe, and ZnSe subject to an external magnetic\nfield, representing a topic that had remained unexplored so far. In these\ncrystals, crystallographic THG is allowed in the electric-dipole approximation,\nso that no strong magnetic-field-induced changes of the THG are expected.\nTherefore, it comes as a total surprise that we observe a drastic enhancement\nof the THG intensity by a factor of fifty for the $1s$-exciton-polariton in\nGaAs in magnetic fields up to 10 T. In contrast, the corresponding enhancement\nis moderate for CdTe and almost neglectful for ZnSe. In order to explain this\nstrong variation, we develop a microscopic theory accounting for the optical\nharmonics generation on exciton-polaritons and analyze the THG mechanisms\ninduced by the magnetic field. The calculations show that the increase of THG\nintensity is dominated by the magnetic field enhancement of the exciton\noscillator strength which is particularly strong for GaAs in the studied range\nof field strengths. The much weaker increase of THG intensity in CdTe and ZnSe\nis explained by the considerably larger exciton binding energies, leading to a\nweaker modification of their oscillator strengths by the magnetic field."
    },
    {
        "anchor": "Suppression of electron scattering resonances in graphene by quantum\n  dots: Transmission of low-energetic electrons through two-dimensional materials\nleads to unique scattering resonances. These resonances contribute to\nphotoemission from occupied bands where they appear as strongly dispersive\nfeatures of suppressed photoelectron intensity. Using angle-resolved\nphotoemission we have systematically studied scattering resonances in epitaxial\ngraphene grown on the chemically differing substrates Ir(111), Bi/Ir, Ni(111)\nas well as in graphene/Ir(111) nanopatterned with a superlattice of uniform Ir\nquantum dots. While the strength of the chemical interaction with the substrate\nhas almost no effect on the dispersion of the scattering resonances, their\nenergy can be controlled by the magnitude of charge transfer from/to graphene.\nAt the same time, a superlattice of small quantum dots deposited on graphene\neliminates the resonances completely. We ascribe this effect to a\nnanodot-induced buckling of graphene and its local rehybridization from\nsp$^{2}$ to sp$^{3}$ towards a three-dimensional structure. Our results suggest\nnanopatterning as a prospective tool for tuning optoelectronic properties of\ntwo-dimensional materials with graphene-like structure.",
        "positive": "A Generic Slater-Koster Description of the Electronic Structure of\n  Centrosymmetric Halide Perovskites: The halide perovskites have truly emerged as efficient optoelectronic\nmaterials and show the promise of exhibiting nontrivial topological phases.\nSince the bandgap is the deterministic factor for these quantum phases, here we\npresent a comprehensive electronic structure study using first-principle\nmethods by considering nine inorganic halide perovskites CsBX$_3$ (B = Ge, Sn,\nPb; X = Cl, Br, I) in their three structural polymorphs (cubic, tetragonal and\northorhombic). A series of exchange-correlations (XC) functionals are examined\ntowards accurate estimation of the bandgap. Furthermore, while thirteen\norbitals are active in constructing the valence and conduction band spectrum,\nhere we establish that a four orbital based minimal basis set is sufficient to\nbuild the Slater-Koster tight-binding model (SK-TB), which is capable of\nreproducing the bulk and surface electronic structure in the vicinity of the\nFermi level. Therefore, like the Wannier based TB model, the presented SK-TB\nmodel can also be considered as an efficient tool to examine the bulk and\nsurface electronic structure of halide family of compounds. As estimated by\ncomparing the model study and DFT band structure, the dominant electron\ncoupling strengths are found to be nearly independent of XC functionals, which\nfurther establishes the utility of the SK-TB model."
    },
    {
        "anchor": "Investigating phase transitions from local crystallographic analysis\n  based on machine learning of atomic environments: Traditionally, phase transitions are explored using a combination of\nmacroscopic functional characterization and scattering techniques, providing\ninsight into average properties and symmetries of the lattice but local atomic\nlevel mechanisms during phase transitions generally remain unknown. Here we\nexplore the mechanisms of a phase transition between the trigonal prismatic and\ndistorted octahedral phases of layered chalogenides in the MoS2 ReS2 system\nfrom the observations of local degrees of freedom, namely atomic positions by\nScanning Transmission Electron Microscopy (STEM). We employ local\ncrystallographic analysis based on machine learning of atomic environments to\nbuild a picture of the transition from the atomic level up and determine local\nand global variables controlling the local symmetry breaking. In particular, we\nargue that the dependence of the average symmetry breaking distortion amplitude\non global and local concentration can be used to separate local chemical and\nglobal electronic effects on transition. This approach allows exploring atomic\nmechanisms beyond the traditional macroscopic descriptions, utilizing the\nimaging of compositional fluctuations in solids to explore phase transitions\nover a range of realized and observed local stoichiometries and atomic\nconfigurations.",
        "positive": "Impact ionization rates for Si, GaAs, InAs, ZnS, and GaN in the $GW$\n  approximation: We present first-principles calculations of the impact ionization rate (IIR)\nin the $GW$ approximation ($GW$A) for semiconductors. The IIR is calculated\nfrom the quasiparticle (QP) width in the $GW$A, since it can be identified as\nthe decay rate of a QP into lower energy QP plus an independent electron-hole\npair. The quasiparticle self-consistent $GW$ method was used to generate the\nnoninteracting hamiltonian the $GW$A requires as input. Small empirical\ncorrections were added so as to reproduce experimental band gaps. Our results\nare in reasonable agreement with previous work, though we observe some\ndiscrepancy. In particular we find high IIR at low energy in the narrow gap\nsemiconductor InAs."
    },
    {
        "anchor": "Highly Stretchable MoS$_2$ Kirigami: We report the results of classical molecular dynamics simulations focused on\nstudying the mechanical properties of MoS$_{2}$ kirigami. Several different\nkirigami structures were studied based upon two simple non-dimensional\nparameters, which are related to the density of cuts, as well as the ratio of\nthe overlapping cut length to the nanoribbon length. Our key finding is\nsignificant enhancements in tensile yield (by a factor of four) and fracture\nstrains (by a factor of six) as compared to pristine MoS$_{2}$ nanoribbons.\nThese results in conjunction with recent results on graphene suggest that the\nkirigami approach may be a generally useful one for enhancing the ductility of\ntwo-dimensional nanomaterials.",
        "positive": "\\txtit{In situ} determination of the anisotropy field in ferromagnetic\n  films using magnetic susceptibility measurements by MOKE: An alternate method of measuring anisotropy fields in thin film ferromagnets\nis demonstrated. The method relies on the magnetic susceptibility in a small\na.c. magnetic field, measured \\txtit{in situ} using the magneto-optic Kerr\neffect (MOKE), and will be useful in situations where more specialized\napparatus are not available, or constraints discourage the use of a large,\nstatic magnetic field. The method is demonstrated for Co/W(110) films, where it\nyields anisotropy fields in agreement with previous studies using more\nconventional torque magnetometry. The sensitivity of the method is demonstrated\nusing CoO/Co/W(110) bilayer films, where the anisotropy due to interfacial\nexchange coupling is detected and used to find the N\\'{e}el temperature of the\nthin CoO layer."
    },
    {
        "anchor": "Magnetic Domains and Surface Effects in Hollow Maghemite Nanoparticles: In the present work, we investigate the magnetic properties of ferrimagnetic\nand noninteracting maghemite (g-Fe2O3) hollow nanoparticles obtained by the\nKirkendall effect. From the experimental characterization of their magnetic\nbehavior, we find that polycrystalline hollow maghemite nanoparticles are\ncharacterized by low superparamagnetic-to-ferromagnetic transition\ntemperatures, small magnetic moments, significant coercivities and\nirreversibility fields, and no magnetic saturation on external magnetic fields\nup to 5 T. These results are interpreted in terms of the microstructural\nparameters characterizing the maghemite shells by means of an atomistic Monte\nCarlo simulation of an individual spherical shell model. The model comprises\nstrongly interacting crystallographic domains arranged in a spherical shell\nwith random orientations and anisotropy axis. The Monte Carlo simulation allows\ndiscernment between the influence of the structure polycrystalline and its\nhollow geometry, while revealing the magnetic domain arrangement in the\ndifferent temperature regimes.",
        "positive": "Electronic Structures in C60-Polymers (review): Variations in the band structures of C60-polymers are studied, when\nconjugation conditions and the electron number are changed. We use a\nsemiempirical model with the Su-Schrieffer-Heeger type electron-phonon\ninteractions. In the neutral one-dimensional C60-polymer, electronic structures\nchange among direct-gap insulators and the metal, depending on the degree of\nconjugations. High pressure experiments could observe such pressure-induced\nmetal-insulator transitions. The C60-polymer doped with one electron per one\nmolecule is always a metal. The energy difference between the highest-occupied\nstate and the lowest-unoccupied state of the neutral system becomes smaller\nupon doping owing to the polaron effects. When the C60-polymer is doped with\ntwo electrons per one C60, the system is insulating. When the conjugation in\nthe direction of the polymer chain is smaller, it is a direct-gap insulator.\nThe energy gap becomes indirect when the conjugation is stronger. We also study\nthe antiferromagnetic phase of AC60 by using a tight-binding model with\nlong-range Coulomb interactions. The antiferromagnetism is well described by\nthe model. The comparison with the photoemission studies shows that the new\nband around the Fermi energy of the AC60 phase can be explaind by the extremely\nlarge intrusion of an energy level into the gap of the neutral system. This\nindicates that the interaction effects among electrons are important in doped\nC60-polymers."
    },
    {
        "anchor": "Valley-dependent properties of monolayer MoSi$_{2}$N$_{4}$,\n  WSi$_{2}$N$_{4}$ and MoSi$_{2}$As$_{4}$: In a recent work, new two-dimensional materials, the monolayer\nMoSi$_{2}$N$_{4}$ and WSi$_{2}$N$_{4}$, have been successfully synthesized in\nexperiment, and several other monolayer materials with the similar structure,\nsuch as MoSi$_{2}$As$_{4}$, have been predicted [{\\color{blue}Science 369,\n670-674 (2020)}]. Here, based on first-principles calculations and theoretical\nanalysis, we investigate the electronic and optical properties of monolayer\nMoSi$_{2}$N$_{4}$, WSi$_{2}$N$_{4}$ and MoSi$_{2}$As$_{4}$. We show that these\nmaterials are semiconductors, with a pair of Dirac-type valleys located at the\ncorners of the hexagonal Brillouin zone. Due to the broken inversion symmetry\nand the effect of spin-orbit coupling, the valley fermions manifest spin-valley\ncoupling, valley-contrasting Berry curvature, and valley-selective optical\ncircular dichroism. We also construct the low-energy effective model for the\nvalleys, calculate the spin Hall conductivity and the permittivity, and\ninvestigate the strain effect on the band structure. Our result reveals\ninteresting valley physics in monolayer MoSi$_{2}$N$_{4}$, WSi$_{2}$N$_{4}$ and\nMoSi$_{2}$As$_{4}$, suggesting their great potential for valleytronics and\nspintronics applications.",
        "positive": "Spectroscopic identification of conjugated polymeric phthalocyanines: Since the discovery of polyphthalocyanines (PPCs) in late 1950s, numerous\nattempts have been made to synthesize this 2D polymer by different approaches.\nInterestingly, the reported IR, Raman and UV-vis spectra of PPCs show drastic\nvariation depending on the synthesis conditions. In this work, we show that the\nspectral data obtained in some works should be assigned not to the target\npolymer, but rather to octacyano phthalocyanine (OCP), which is an early step\nof the reaction. We discuss the spectral signatures of the well-polymerized and\nmonomeric PCs based on reliable experimental data and support the spectral\nassignments with DFT calculations."
    },
    {
        "anchor": "Spin control in heteromagnetic nanostructures: The rapidly expanding research in Spintronics, the electronics utilizing the\nelectron spin instead of its charge, is driven by the very interesting\npotential applications. The actual task is to develop principles for the spin\nmanipulations in spintronic devices. In this Report we suggest and verify\nexperimentally a concept of heteromagnetic semiconductor structures. It is\nbased on spin diffusion between layers of the nanostructure with different\nmagnetic properties and allows controlling the spin-switching rate for magnetic\nions. A ten times increase of spin-lattice relaxation rate of magnetic Mn-ions\nis achieved in (Zn,Mn)Se/(Be,Mn)Te heteromagnetic structures with an\ninhomogeneous distribution of Mn-ions.",
        "positive": "Shubnikov-de Haas oscillations, weak antilocalization effect and large\n  linear magnetoresistance in the putative topological superconductor LuPdBi: We present electronic transport and magnetic properties of single crystals of\nsemimetallic half-Heusler phase LuPdBi, having theoretically predicted band\ninversion requisite for nontrivial topological properties. The compound\nexhibits superconductivity below a critical temperature $T_{\\rm c}=1.8\\,$K,\nwith a zero-temperature upper critical field $B_{\\rm c2}\\approx2.3\\,$T.\nAlthough superconducting state is clearly reflected in the electrical\nresistivity and magnetic susceptibility data, no corresponding anomaly can be\nseen in the specific heat. Temperature dependence of the electrical resistivity\nsuggests existence of two parallel conduction channels: metallic and\nsemiconducting, with the latter making negligible contribution at low\ntemperatures. The magnetoresistance is huge and clearly shows a weak\nantilocalization effect in small magnetic fields. Above about 1.5 T, the\nmagnetoresistance becomes linear and does not saturate in fields up to 9 T. The\nlinear magnetoresistance is observed up to room temperature. Below 10 K, it is\naccompanied by Shubnikov-de Haas oscillations. Their analysis reveals charge\ncarriers with effective mass of $0.06\\,m_e$ and a Berry phase very close to\n$\\pi$, expected for Dirac-fermion surface states, thus corroborating\ntopological nature of the material."
    },
    {
        "anchor": "Sodium Diffusion and Dynamics in Na2Ti3O7: Neutron Scattering and\n  Ab-initio Simulations: We have performed quasielastic and inelastic neutron scattering (QENS and\nINS) measurements from 300 K to 1173 K to investigate the Na-diffusion and\nunderlying host dynamics in Na2Ti3O7. The QENS data show that the Na atoms\nundergo localized jumps up to 1173 K. The ab-initio molecular dynamics (AIMD)\nsimulations supplement the measurements and show 1-d long-ranged diffusion\nalong the a-axis above 1500 K. The simulations indicate that the occupancy of\nthe interstitial site is critical for long-range diffusion. The\nnudged-elastic-band (NEB) calculation confirmed that the activation energy\nbarrier is lowest for diffusion along the a-axis. In the experimental phonon\nspectra the peaks at 10 and 14 meV are dominated by Na dynamics that disappear\non warming, suggesting low-energy phonons significantly contribute to large Na\nvibrational amplitude at elevated temperatures that enhances the Na hopping\nprobability. We have also calculated the mode Gr\\\"uneisen parameters of the\nphonons and thereby calculated the volume thermal expansion coefficient, which\nis found to be in excellent agreement with available experimental data.",
        "positive": "Adsorption-controlled growth of La-doped BaSnO3 by molecular-beam\n  epitaxy: Epitaxial La doped BaSnO3 films were grown in an adsorption controlled regime\nby molecular beam epitaxy, where the excess volatile SnOx desorbs from the film\nsurface. A film grown on a (001) DyScO3 substrate exhibited a mobility of 183\ncm^2 V^-1 s^-1 at room temperature and 400 cm^2 V^-1 s^-1 at 10 K, despite the\nhigh concentration (1.2x10^11 cm^-2) of threading dislocations present. In\ncomparison to other reports, we observe a much lower concentration of (BaO)2\nRuddlesden Popper crystallographic shear faults. This suggests that in addition\nto threading dislocations that other defects possibly (BaO)2 crystallographic\nshear defects or point defects significantly reduce the electron mobility."
    },
    {
        "anchor": "Anti-vortex dynamics in magnetic nanostripes: In a thin magnetic nanostripe, an anti-vortex nucleates inside a moving\ndomain wall when driven by an in-plane magnetic field greater than the\nso-called Walker field. The nucleated anti-vortex must cross the width of the\nnanostripe before the domain wall can propagate again, leading to low average\ndomain wall speeds. A large out-of-plane magnetic field, applied\nperpendicularly to the plane of the nanostripe, inhibits the nucleation of the\nanti-vortex leading to fast domain wall speeds for all in-plane driving fields.\nWe present micromagnetic simulation results relating the anti-vortex dynamics\nto the strength of the out-of-plane field. An asymmetry in the motion is\nobserved which depends on the alignment of the anti-vortex core magnetic\nmoments to the direction of the out-of-plane field. The size of the core is\ndirectly related to its crossing speed, both depending on the strength of the\nperpendicular field and the alignment of the core moments and direction of the\nout-of-plane field.",
        "positive": "Element-resolved thermodynamics of magnetocaloric LaFe$_{13-x}$Si$_x$: By combination of two independent approaches, nuclear resonant inelastic\nX-ray scattering and first-principles calculations in the framework of density\nfunctional theory, we determine the element-resolved vibrational density of\nstates in the ferromagnetic low temperature and paramagnetic high temperature\nphase of LaFe$_{13-x}$Si$_x$. This allows us to derive the lattice and\nelectronic contribution to the entropy change at the first-order phase\ntransformation, which are both of considerable magnitude. The change in lattice\nentropy is dominated by magneto-elastic softening, which originates from the\nitinerant electron metamagnetism associated with Fe. This counteracts the large\nvolume change at the transition and leads to an unexpected, cooperative\nbehavior of magnetic, vibrational and electronic entropy change, which is\nresponsible for the large magneto- and barocaloric effect observed for this\nmaterial."
    },
    {
        "anchor": "Influence of ion implantation on the magnetic and transport properties\n  of manganite films: We have used oxygen ions irradiation to generate controlled structural\ndisorder in thin manganite films. Conductive atomic force microscopy CAFM),\ntransport and magnetic measurements were performed to analyze the influence of\nthe implantation process in the physical properties of the films. CAFM images\nshow regions with different conductivity values, probably due to the random\ndistribution of point defect or inhomogeneous changes of the local Mn3+/4+\nratio to reduce lattice strains of the irradiated areas. The transport and\nmagnetic properties of these systems are interpreted in this context.\nMetal-insulator transition can be described in the frame of a percolative\nmodel. Disorder increases the distance between conducting regions, lowering the\nobserved TMI. Point defect disorder increases localization of the carriers due\nto increased disorder and locally enhanced strain field. Remarkably, even with\nthe inhomogeneous nature of the samples, no sign of low field magnetoresistance\nwas found. Point defect disorder decreases the system magnetization but doesn t\nseem to change the magnetic transition temperature. As a consequence, an\nimportant decoupling between the magnetic and the metal-insulator transition is\nfound for ion irradiated films as opposed to the classical double exchange\nmodel scenario.",
        "positive": "Unexpected Giant Microwave Conductivity in a Nominally Silent BiFeO3\n  Domain Wall: Nanoelectronic devices based on ferroelectric domain walls (DWs), such as\nmemories, transistors, and rectifiers, have been demonstrated in recent years.\nPractical high-speed electronics, on the other hand, usually demand operation\nfrequencies in the giga-Hertz (GHz) regime, where the effect of dipolar\noscillation is important. In this work, an unexpected giant GHz conductivity on\nthe order of 103 S/m is observed in certain BiFeO3 DWs, which is about 100,000\ntimes greater than the carrier-induced dc conductivity of the same walls.\nSurprisingly, the nominal configuration of the DWs precludes the ac conduction\nunder an excitation electric field perpendicular to the surface. Theoretical\nanalysis shows that the inclined DWs are stressed asymmetrically near the film\nsurface, whereas the vertical walls in a control sample are not. The resultant\nimbalanced polarization profile can then couple to the out-of-plane microwave\nfields and induce power dissipation, which is confirmed by the phase-field\nmodeling. Since the contributions from mobile-carrier conduction and\nbound-charge oscillation to the ac conductivity are equivalent in a microwave\ncircuit, the research on local structural dynamics may open a new avenue to\nimplement DW nano-devices for RF applications."
    },
    {
        "anchor": "Magnetization of Zn1-xCoxO nanoparticles: single-ion anisotropy and spin\n  clustering: The magnetization of Zn1-xCoxO (0.0055 < x < 0.073) nanoparticles has been\nmeasured as a function of temperature T (1.7 K < T , 10 K) and for magnetic\nfield up to 65 kOe using a SQUID magnetometer. Samples were synthesized by\nthree different growth methods: microwave-assisted hydrothermal, combustion\nreaction and sol-gel. For all studied samples, the magnetic properties derive\nfrom the antiferromagnetic (AF) spin clustering due to the Co2+ nearest\nneighbors. At T >= 6 K, the magnetization of the Co2+ ions has a Brillouin-type\nbehavior, but below 6 K, it shows a notable deviation. We have shown that the\nobserved deviation may be derived from single-ion anisotropy (SIA) with\nuniaxial symmetry. Results of fits show that the axial-SIA parameter D\n(typically D = 4.4 K) is slightly larger that the bulk value D = 3.97 K. No\nsignificant change of D has been observed as a function of the Co concentration\nor the growth process. For each sample, the SIA fit gave also the effective\nconcentration (x) corresponding to the technical saturation value of the\nmagnetization. Comparison of the concentration dependence of x with predictions\nbased on cluster models shows an enhancement of the AF spin clustering\nindependent of the growth method. This is ascribed to a clamped non-random\ndistribution of the cobalt ions in the nanoparticles. The approach of the local\nconcentration (xL) has been used to quantify the observed deviation from\nrandomicity. Assuming a ZnO core/ Zn1-xCoxO shell nanoparticle, the thickness\nof the shell has been determined from the ratio xL/x.",
        "positive": "Experiments on transformation thermodynamics: Molding the flow of heat: It has recently been shown theoretically that the time-dependent heat\nconduction equation is form-invariant under curvilinear coordinate\ntransformations. Thus, in analogy to transformation optics, fictitious\ntransformed space can be mapped onto (meta-)materials with spatially\ninhomogeneous and anisotropic heat-conductivity tensors in the laboratory\nspace. On this basis, we design, fabricate, and characterize a micro-structured\nthermal cloak that molds the flow of heat around an object in a metal plate.\nThis allows for transient protection of the object from heating, while\nmaintaining the same downstream heat flow as without object and cloak."
    },
    {
        "anchor": "A model for collisions in granular gases: We propose a model for collisions between particles of a granular material\nand calculate the restitution coefficients for the normal and tangential motion\nas functions of the impact velocity from considerations of dissipative\nviscoelastic collisions. Existing models of impact with dissipation as well as\nthe classical Hertz impact theory are included in the present model as special\ncases. We find that the type of collision (smooth, reflecting or sticky) is\ndetermined by the impact velocity and by the surface properties of the\ncolliding grains. We observe a rather nontrivial dependence of the tangential\nrestitution coefficient on the impact velocity.",
        "positive": "Atomically thin gallium layers from solid-melt exfoliation: Among the large number of promising two-dimensional (2D) atomic layer\ncrystals, true metallic layers are rare. Through combined theoretical and\nexperimental approaches, we report on the stability and successful exfoliation\nof atomically thin gallenene sheets, having two distinct atomic arrangements\nalong crystallographic twin directions of the parent alpha-gallium. Utilizing\nthe weak interface between solid and molten phases of gallium, a solid-melt\ninterface exfoliation technique is developed to extract these layers. Phonon\ndispersion calculations show that gallenene can be stabilized with bulk gallium\nlattice parameters. The electronic band structure of gallenene shows a\ncombination of partially filled Dirac cone and the non-linear dispersive band\nnear Fermi level suggesting that gallenene should behave as a metallic layer.\nFurthermore it is observed that strong interaction of gallenene with other 2D\nsemiconductors induces semiconducting to metallic phase transitions in the\nlatter paving the way for using gallenene as interesting metallic contacts in\n2D devices."
    },
    {
        "anchor": "Current injection by coherent one- and two-photon excitation in graphene\n  and its bilayer: Coherent control of optically-injected carrier distributions in single and\nbilayer graphene allows the injection of electrical currents. Using a\ntight-binding model and Fermi's golden rule, we derive the carrier and\nphotocurrent densities achieved via interference of the quantum amplitudes for\ntwo-photon absorption at a fundamental frequency, $\\omega$, and one-photon\nabsorption at the second harmonic, $2\\omega$. Strong currents are injected\nunder co-circular and linear polarizations. In contrast, opposite-circular\npolarization yields no net current. For single-layer graphene, the magnitude of\nthe current is unaffected by the rotation of linear-polarization axes, in\ncontrast with the bilayer and with conventional semiconductors. The dependence\nof the photocurrent on the linear-polarization axes is a clear and measurable\nsignature of interlayer coupling in AB-stacked multilayer graphene. We also\nfind that single and bilayer graphene exhibit a strong, distinct\nlinear-circular dichroism in two-photon absorption.",
        "positive": "Steering alkyne homocoupling with on-surface synthesized catalysts: We report a multi-step on-surface synthesis strategy. The first step consists\nin the surface-supported synthesis of metal-organic complexes, which are\nsubsequently used as catalysts to steer on-surface alkyne coupling reactions.\nIn addition, we analyze and compare the electronic properties of the different\ncoupling motifs obtained."
    },
    {
        "anchor": "Glass fracture surface energy calculated from crystal structure and\n  bond-energy data: We present a novel method to predict the fracture surface energy, {\\gamma},\nof isochemically crystallizing silicate glasses using readily available\ncrystallographic structure data of their crystalline counterpart and tabled\ndiatomic chemical bond energies, D0. The method assumes that {\\gamma} equals\nthe fracture surface energy of the most likely cleavage plane of the crystal.\nCalculated values were in excellent agreement with those calculated from glass\ndensity, network connectivity and D0 data in earlier work. This finding\ndemonstrates a remarkable equivalence between crystal cleavage planes and glass\nfracture surfaces.",
        "positive": "Quantum-chemical studies of rutile nanoparticles toxicity I. Defect-free\n  rod-like model clusters: Using semiempirical PM6 method, the structures of a rod-like [Ti40O124H81]-7\nmodel cluster and of the [Ti40O124H81Cu]-5 ones with Cu2+ coordinated at\nvarious sites were optimized. If the relative toxicity of individual Ti centers\nin rod-like rutile nanoparticles can be evaluated by the electron density\ntransfer to a Cu2+ probe, its maximal values may be ascribed to the\npentacoordinated corner and hexacoordinated edge ones with three Ti-OH bonds.\nHowever, these centers exhibit the least negative interaction energies which\ncan be compensated by the significantly better accessibility of the corner Ti\ncenter in comparison with the remaining ones. The Ti centers with the most\nnegative interaction energy parameters exhibit the lowest extent of the\nelectron density transfer to a Cu2+ probe. The rutile nanoparticles destruction\nstarts at pentacoordinated Ti face centers"
    },
    {
        "anchor": "Modeling recombination processe in RE doped Up-Conversion nanocrystals: Up-conversion nanocrystals (UCNCs) are a new class of nonlinear optical\nmaterials converting low energy excitation to high energy emission. Recent\nadvances in synthesis techniques enable a control over size, shape, emission\ncolor purity as well as optical tuning [1]. Those UCNCs are characterized by\nhigh surface to volume ratio allowing interesting attributes such as water\nsolubility and biological functionality. UCNCs usually consist of an inorganic\nhost that is doped with Ln^{3+} ions. The most efficient host matrix known is\nthe one used to test our model, namely, NaGdF_4 nanocrystals co-doped with\nEr^{3+} as an acceptor/activator and Yb^{3+} as a donor/sensitizer. In this\nwork, we introduce the theoretical background needed to understand the nature\nof ion-ion interactions occurring in these systems as well as the details of\nthe 4f transitions characteristic of RE-ions. In the second chapter, we present\nour model through a system of rate equations corresponding to a custom energy\ndiagram. Then, we show our simulations producing fits of Time Resolved Photo\nLuminescence (TRPL) data. Finally, we construct an improved model aiming to\nencompass all the processes that seem to be involved in the luminescence of the\nsamples studied and we present the achievements of such approach.",
        "positive": "Unveiling the electrical and thermoelectric properties of highly\n  degenerate indium selenide thin films: Indication of In3Se4 phase: The effects of annealing and variation of temperature on the electrical and\nthermoelectric properties of e-beam evaporated InSe thin films has been\ninvestigated in details. The XRD study demonstrates that the as-deposited InSe\nthin films are amorphous while they become polycrystalline with the presence of\nIn3Se4 phase after annealing. The SEM micrographs reveal that the surfaces of\nas-deposited films are smooth whereas they become non-uniform due to annealing.\nThe heating and cooling cycles of the as-deposited films exhibit that the\nresistivity of the films shows an irreversible phase-transition and become\nstable after 3-4 successive heat-treatment operations in air. The electrical\nconductivity of annealed InSe thin films shows a highly degenerate\nsemiconducting (metallic) behavior. The thermopower of the annealed films\nindicates that InSe thin film is a highly degenerate n-type semiconductor i.e.\nmetallic. Thickness dependence thermopower obeys the Fuchs-Sondheimer theory.\nThe optical band gap of the annealed films increases as compared to the\nas-deposited films. These results indicate that InSe thin films encounter a\nphase-transformation from In2Se3 to a new In3Se4 metallic phase with an optical\nband gap of ~1.8 eV due to heat-treatment."
    },
    {
        "anchor": "Interpretation of EMF data in Ag-Au-S system: The EMF dependencies for Ag-Au-S systems were analyzed and it was found that\nthe reactions described in reference [1] are inaccurate. Additionally, the\nassumption that the equilibrium state of Au remains unchanged during the\nmeasurement process was shown to be incorrect. Based on the EMF data provided\nin White's 1957 paper, the compositions of the alloys involved in the reactions\nwere determined. The reaction equations were then modified to include\ntemperature dependencies of the alloy composition. The resulting equations are\nas follows:\n  $1/(1-x)Ag(cr) + Ag_{3}AuS_{2}(cr) = 2Ag_{2}S(cr) + 1/(1-x)Ag_{x}Au_{1-x},\nx=0.4535-3.513*10^{-4}T$\n  $1/(1-x)Ag(cr) + 2AgAuS(cr) = Ag_{3}AuS_{2}(cr) + 1/(1-x)Ag_{x}Au_{1-x},\nx=0.3092-3.341*10^{-4}T$\n  $1/(1-x)Ag(cr) + Au_{2}S(cr) = AgAuS(cr) + 1/(1-x)Ag_{x}Au_{1-x}, x=\n-0.0131+5.769*10^{-5}T$\n  The validity of these reaction equations was demonstrated, and the accurate\nthermodynamic functions for the phases were determined based on these\nequations.",
        "positive": "Simulation study of negative thermal expansion in yttrium tungstate\n  Y2W3O12: A simulation study of negative thermal expansion in Y2W3O12 was carried out\nusing calculations of phonon dispersion curves through the application of\ndensity functional perturbation theory. The mode eigenvectors were mapped onto\nflexibility models and results compared with calculations of the mode Gruneisen\nparameters. It was found that many lower-frequency phonons contribute to\nnegative thermal expansion in Y2W3O12, all of which can be described in terms\nof rotations of effectively rigid WO4 tetrahedra and Y-O rods. The results are\nstrikingly different from previous phonon studies of higher-symmetry materials\nthat show negative thermal expansion."
    },
    {
        "anchor": "Landau-Lifshitz theory of single susceptibility Maxwell equations: The conflicting arguments given in the discussion forum of Metamaterials 2011\non the possible forms of macroscopic Maxwell equations are lead to a\nconvergence by noting the relationship among the employed material variables\nfor each scheme. The three schemes by Chipouline et al. using (A) standard\n$\\Vec{P}$ and $\\Vec{M}$ (Casimir form), (B) generalized electric polarization\n$\\Vec{P}_{LL}$ (Landau-Lifshitz form), (C) generalized magnetic polarization\n$\\Vec{M}_{A}$ (Anapole form) are compared with (D) the present author's scheme\nusing standard current density $\\Vec{J}$. From the reversible relations among\nthe transverse components of these vectors, one can easily rewrite one scheme\ninto another. The scheme (D), the only one among the four providing the\nfirst-principles expressions of susceptibility and also leading to a\nnon-phenomenological Casimir form in terms of the four generalized\nsusceptibilities between $\\{\\Vec{P},\\Vec{M}\\}$ and $\\{\\Vec{E},\\Vec{B}\\}$, is\nconcluded to be a more natural form than (B) and (C) as a single susceptibility\ntheory.",
        "positive": "Anomalous Lattice Parameter of Magnetic Semiconductor Alloys: The addition of transition metals (TM) to III-V semiconductors radically\nchanges their electronic, magnetic and structural properties. In contrast to\nthe conventional semiconductor alloys, the lattice parameter in magnetic\nsemiconductor alloys, including the ones with diluted concentration (the\ndiluted magnetic semiconductors - DMS), cannot be determined uniquely from the\ncomposition. By using first-principles calculations, we find a direct\ncorrelation between the magnetic moment and the anion-TM bond lengths. We\nderive a simple formula that determines the lattice parameter of a particular\nmagnetic semiconductor by considering both the composition and magnetic moment.\nThe formula makes accurate predictions of the lattice parameter behavior of\nAlMnN, AlCrN, GaMnN, GaCrN, GaCrAs and GaMnAs alloys. This new dependence can\nexplain some of the hitherto puzzling experimentally observed anomalies, as\nwell as, stimulate other kind of theoretical and experimental investigations."
    },
    {
        "anchor": "Magnetic tunnel junctions with a B2-ordered CoFeCrAl equiatomic Heusler\n  alloy: The equiatomic quaternary Heusler alloy CoFeCrAl is a candidate material for\nspin-gapless semiconductors (SGSs). However, to date, there have been no\nexperimental attempts at fabricating a junction device. This paper reports a\nfully epitaxial (001)-oriented MgO barrier magnetic tunnel junction (MTJ) with\nCoFeCrAl electrodes grown on a Cr buffer. X-ray and electron diffraction\nmeasurements show that the (001) CoFeCrAl electrode films with atomically flat\nsurfaces have a $B2$-ordered phase. The saturation magnetization is 380\nemu/cm$^3$, almost the same as the value given by the Slater--Pauling--like\nrule, and the maximum tunnel magnetoresistance ratios at 300 K and 10 K are 87%\nand 165%, respectively. Cross-sectional electron diffraction analysis shows\nthat the MTJs have MgO interfaces with fewer dislocations. The temperature- and\nbias-voltage-dependence of the transport measurements indicates magnon-induced\ninelastic electron tunneling overlapping with the coherent electron tunneling.\nX-ray magnetic circular dichroism (XMCD) measurements show a ferromagnetic\narrangement of the Co and Fe magnetic moments of $B2$-ordered CoFeCrAl, in\ncontrast to the ferrimagnetic arrangement predicted for the $Y$-ordered state\npossessing SGS characteristics. Ab-initio calculations taking account of the\nCr-Fe swap disorder qualitatively explain the XMCD results. Finally, the effect\nof the Cr-Fe swap disorder on the ability for electronic states to allow\ncoherent electron tunneling is discussed.",
        "positive": "Universal relaxor polarization in Pb(Mg1/3Nb2/3)O3 and related materials: The dielectric permittivity e at frequencies from [10^(-1) -10^(-5)] Hz to\n10^5 Hz is studied in perovskite (1-x)Pb(Mg1/3Nb2/3)O3 - xPbTiO3 relaxor\nferroelectric ceramics of different compositions x = 0.35, 0.25 and 0, which\nexhibit, below the temperature of the diffuse epsilon'(T) maximum Tm, a\ntetragonal ferroelectric, a rhombohedral ferroelectric and a nonergodic relaxor\nphase, respectively. The universal relaxor dispersion previously observed at\ntemperatures near and above Tm in the ceramics of x=0.25, is also found to\nexist in other compositions. This dispersion is described by the fractional\npower dependence of the real and imaginary parts of susceptibility on\nfrequency. The real part of the universal relaxor susceptibility chi'U is only\na comparatively small fraction of the total permittivity epsilon', but chi\"U is\nthe dominant contribution to the losses in a wide frequency-temperature range\nabove Tm. In the high-temperature phase a quadratic divergent temperature\nbehavior is observed for all the three compositions studied. The universal\nrelaxor susceptibility is attributed to the polarization of polar nanoregions,\nwhich are inherent in the relaxor ferroelectrics. A microscopic model of this\npolarization is proposed, according to which the dipole moments of some\n('free') unit cells inside polar nanoregion can freely choose several different\ndirections, while the direction of the total moment of the nanoregion remains\nthe same. The ensemble of interacting polar nanoregions is described in terms\nof a standard spherical model, which predicts the quadratic divergence of\nsusceptibility above the critical temperature, in agreement with the\nexperimental results."
    },
    {
        "anchor": "Molecular Dynamic Simulation of Liquid-Vapor Coexistence of Metals\n  Modeled Using Modified Empirical Pair Potentials: We propose a modified form of pair potential for metals. The parameters of\nthe potential are obtained by fitting the cold curve of the potential to that\nobtained from the ab-initio calculations. Parameters have been obtained for\nAluminum, Copper, Sodium and Potassium. To test the accuracy of the potentials,\nwe performed particle-transfer molecular dynamics simulations and obtained the\nliquid-vapor coexistence curves of the above metals. We found that, in the\ncases of Sodium and Potassium, the present results improve significantly over\nthose obtained from Morse potential (J.K. Singh et. al., Fluid Phase Equilibria\n248(2006)). In the cases of Aluminum and Copper, the present results are closer\nto those obtained from the Morse potential. We also obtained isobars of\nAluminum and Copper at 0.3GPa from NPT ensemble simulations. We observed that\nthe isobars obtained using the Morse potential and the modified potentials are\nin close agreement in both the cases. The obtained isobar of Copper is in\nreasonable agreement with the experimental isobar while that of Aluminum is\nslightly deviating from the experimental isobar.",
        "positive": "Structural transformation and magnetic properties of\n  (Fe$_{0.7}$Co$_{0.3}$)$_2$B alloys doped with 5$d$ elements: A combined\n  first-principles and experimental study: (Fe,Co)$_2$B-based compounds with specified 5$d$ substitutions are considered\nas promising materials for permanent magnets without rare-earth elements. We\nconducted a combined first-principles and experimental study focused on\n(Fe$_{0.7}$Co$_{0.3}$)$_2$B alloys doped with W and Re. First, we used\nfull-potential local-orbital scheme to systematically investigate (Fe,Co)$_2$B\nalloys with 3$d$, 4$d$, and 5$d$ substitutions. Computational analyses showed a\nsignificant increase in magnetocrystalline anisotropy only for the Re doped\nsample. Simultaneously, the structural and magnetic properties of the\n(Fe$_{0.7-x}$Co$_{0.3-x}$M$_{2x}$)$_2$B ($M$ = W, Re; $x$ = 0, 0.025) alloys\nwere investigated experimentally. The desired (Fe,Co)$_2$B tetragonal phase was\nsynthesized by heat treatment of amorphous precursors. We observed that\nisothermal annealing increases the coercive field of all samples. However, the\nobtained values, without further optimization, are well below the threshold for\npermanent magnet applications. Nevertheless, annealing of substituted samples\nat 750$^o$C significantly improves saturation magnetization values.\nFurthermore, M\\\"{o}ssbauer spectroscopy revealed a reduction of the hyperfine\nfield due to the presence of Co atoms in the (Fe,Co)$_2$B phase, where\nadditional defect positions are formed by Re and W. Radio-frequency\nM\\\"{o}ssbauer studies showed that (Fe$_{0.7}$Co$_{0.3}$)$_2$B and the\nW-substituted sample began to crystallize when exposed to an radio frequency\nfield of 12 Oe, indicating that the amorphous phase is stabilized by Re\nsubstitution. Improvement of thermal stability of\n(Fe$_{0.675}$Co$_{0.275}$Re$_{0.05}$)$_2$B alloy is consistent with the results\nof differential scanning calorimetry and thermomagnetic measurements."
    },
    {
        "anchor": "An ab initio approach to understand the structural, thermophysical,\n  electronic, and optical properties of binary silicide SrSi2: A double Weyl\n  semimetal: A large number of hitherto unexplored elastic, thermophysical, acoustic, and\noptoelectronic properties of a double Weyl semimetal SrSi2 have been\ninvestigated in this study. Density functional theory (DFT) based methodology\nhas been employed. Analyses of computed elastic parameters reveal that SrSi2 is\na mechanically stable, ductile, moderately machinable, and relatively soft\nmaterial. The compound is predicted to be dynamically stable and possesses\nsignificant metallic bonding. Study of thermophysical properties, namely, Debye\ntemperature, Gr\\\"uneisen parameter, acoustic parameters, melting temperature,\nheat capacity, thermal expansion coefficient, and dominant phonon mode is also\nindicative of soft nature of SrSi2. The electronic band structure calculations\nwithout and with spin-orbit coupling disclose semimetallic character with clear\nWeyl nodes close to the Fermi level. The electronic dispersion is anisotropic\ncharacterized by nearly flat and linear regions within the Brillouin zone.\nOptical parameters at different photon energies are investigated. SrSi2 shows\nexcellent nonselective reflection spectrum across an extended range of energy\nencompassing the visible region implying that the compound under study has\nsignificant potential to be used as an efficient solar energy reflector. SrSi2\nabsorbs ultraviolet light quite efficiently. The compound also possesses high\nrefractive index in the low energy. All these optical features can be useful in\noptoelectronic device applications.",
        "positive": "Magnetization and Thermal Entanglement of the Spin-1 Ising-Heisenberg\n  Polymer Chain: We establish a solvable Heisenberg-Ising model on a spin-1 Ni-containing\npolymer chain, $[Ni (NN'-dmen) (\\mu-N_3)_2]$, with $NN'-dmen$ being\n$NN'-dimethylethylenediamine$, that fully covers the interaction\ncharacteristics of the material and by which, we can characterize all the\npeculiar magnetic features of the polymer, which has been partly studied in\nexperiment. By purely analytical calculations, we can see that the\nmagnetization exhibits three plateaus at zero, mid, and 3/4 of the saturation\nvalue at low temperatures below 2 K. The corresponding featuring peaks of\nmagnetic susceptibility are clearly shown. The model also displays plateaus in\nthermal entanglement that captures the one-to-one correspondence between\nthermal entanglement plateaus and those of the magnetization. The calculations\nare done by the transfer matrix technique."
    },
    {
        "anchor": "Linking Phase-Field and Atomistic Simulations to Model Dendritic\n  Solidification in Highly Undercooled Melts: Even though our theoretical understanding of dendritic solidification is\nrelatively well developed, our current ability to model this process\nquantitatively remains extremely limited. This is due to the fact that the\nmorphological development of dendrites depends sensitively on the degree of\nanisotropy of capillary and/or kinetic properties of the solid-liquid\ninterface, which is not precisely known for materials of metallurgical\ninterest. Here we simulate the crystallization of highly undercooled nickel\nmelts using a computationally efficient phase-field model together with\nanisotropic properties recently predicted by molecular dynamics simulations.\nThe results are compared to experimental data and to the predictions of a\nlinearized solvability theory that includes both capillary and kinetic effects\nat the interface.",
        "positive": "Quasi-free Standing Epitaxial Graphene on SiC by Hydrogen Intercalation: Quasi-free standing epitaxial graphene is obtained on SiC(0001) by hydrogen\nintercalation. The hydrogen moves between the 6root3 reconstructed initial\ncarbon layer and the SiC substrate. The topmost Si atoms which for epitaxial\ngraphene are covalently bound to this buffer layer, are now saturated by\nhydrogen bonds. The buffer layer is turned into a quasi-free standing graphene\nmonolayer with its typical linear pi-bands. Similarly, epitaxial monolayer\ngraphene turns into a decoupled bilayer. The intercalation is stable in air and\ncan be reversed by annealing to around 900 degrees Celsius."
    },
    {
        "anchor": "H-T Phase Diagram of Rare-Earth -- Transition Metal Alloy in the\n  Vicinity of the Compensation Point: Anomalous hysteresis loops of ferrimagnetic amorphous alloys in high magnetic\nfield and in the vicinity of the compensation temperature have so far been\nexplained by sample inhomogeneities. We obtain H-T magnetic phase diagram for\nferrimagnetic GdFeCo alloy using a two-sublattice model in the paramagnetic\nrare-earth ion approximation and taking into account rare-earth (Gd) magnetic\nanisotropy. It is shown that if the magnetic anisotropy of the $f$-sublattice\nis larger than that of the $d$-sublattice, the tricritical point can be at\nhigher temperature than the compensation point. The obtained phase diagram\nexplains the observed anomalous hysteresis loops as a result of high-field\nmagnetic phase transition, the order of which changes with temperature. It also\nimplies that in the vicinity of the magnetic compensation point the shape of\nmagnetic hysteresis loop is strongly temperature dependent.",
        "positive": "Electron and phonon properties of noncentrosymmetric RhGe from ab initio\n  calculations: Band structure, Fermi surface, and phonon dispersions of noncentrosymmetric\nB20-type RhGe are calculated ab initio for the first time and their evolution\nwith increasing pressure is investigated. We consider in detail\nsymmetry-conditioned features of the band structure, as well as\npressure-induced changes in the Fermi surface topology, which are expected to\naffect the thermopower of RhGe. We also report on special calculations of\nelectric field gradients on the Rh and Ge nuclei and compare these results with\na very recent 111 Cd-TDPAC study of B20-RhGe."
    },
    {
        "anchor": "Electrical Detection of Spin Accumulation at a Ferromagnet-Semiconductor\n  Interface: We show that the accumulation of spin-polarized electrons at a forward-biased\nSchottky tunnel barrier between Fe and n-GaAs can be detected electrically. The\nspin accumulation leads to an additional voltage drop across the barrier that\nis suppressed by a small transverse magnetic field, which depolarizes the spins\nin the semiconductor. The dependence of the electrical accumulation signal on\nmagnetic field, bias current, and temperature is in good agreement with the\npredictions of a drift-diffusion model for spin-polarized transport.",
        "positive": "A simple scaling derivation of the shear thinning power law exponent in\n  entangled polymer melts: This paper has been withdrawn by the author, because it final version is\npublished in: N. Fatkullin, C. Mattea, S. Stapf, Polymer 52 (2011) 3522."
    },
    {
        "anchor": "A heterojunction modulation-doped Mott transistor: A heterojunction Mott field effect transistor (FET) is proposed that consists\nof an epitaxial channel material that exhibits an electron-correlation-induced\nMott metal-to-insulator transition. The Mott material is remotely (modulation)\ndoped with a degenerately doped conventional band insulator. An applied voltage\nmodulates the electron transfer from the doped band insulator to the Mott\nmaterial and produces transistor action by inducing an insulator-to-metal\ntransition. Materials parameters from rare-earth nickelates and SrTiO3 are used\nto assess the potential of the \"modulation-doped Mott FET\" (ModMottFET or\nMMFET) as a next-generation switch. It is shown that the MMFET is characterized\nby unique \"charge gain\" characteristics as well as competitive\ntransconductance, small signal gain and current drive.",
        "positive": "Ferroelectric phenomena in CdSnO3: a first-principles study: The phonon spectrum of cubic cadmium metastannate and the crystal structures\nof its distorted phases were calculated from first principles within the\ndensity functional theory. It is shown that the phonon spectrum and the energy\nspectrum of distorted phases in $\\alpha$-CdSnO$_3$ are surprisingly similar to\nthe corresponding spectra of CdTiO$_3$. The ground state of $\\alpha$-CdSnO$_3$\nis the ferroelectric $Pbn2_1$ phase; the energy gain accompanying the phase\ntransition from the nonpolar $Pbnm$ phase to this phase is $\\sim$30 meV and the\nspontaneous polarization in it is 0.25 C/m$^2$. An analysis of the eigenvector\nof the ferroelectric mode in $\\alpha$-CdSnO$_3$ and calculations of the partial\ndensities of states indicates that the ferroelectric instability in this\ncrystal, which does not contain $d$ transition elements, is associated with the\nformation of a covalent bonding between Cd and O atoms."
    },
    {
        "anchor": "$d^0$-$d$ half-Heusler alloys: A class of future spintronic materials: It is shown by rigorous ab initio calculations that half-Heusler alloys of\ntransition metals and $d^0$ metals, defined by the valence electronic\nconfiguration $ns^{1,2},(n-1)d^0$, can produce all kinds of half-metallic\nbehavior including the elusive Dirac half-semimetallicity that is reported for\nthe first time in the real 3D material CoKSb. Together with the predicted\nmagnetic and chemical stability, this paves the way for massless and\ndissipationless spintronics of the future. Furthermore, the introduction of\n$d^0$ atoms is shown to stabilize the otherwise instable chemical structure of\nzinc-blende transition metal pnictides and chalcogeneides without altering the\n$p$-$d$ exchange that is mainly responsible for their half-metallicity,\ntherefore, making their application in spintronic devices feasible.",
        "positive": "Epitaxial growth of (111)-oriented LaAlO$_3$/LaNiO$_3$ ultra-thin\n  superlattices: The epitaxial stabilization of a single layer or superlattice structures\ncomposed of complex oxide materials on polar (111) surfaces is severely\nburdened by reconstructions at the interface, that commonly arise to neutralize\nthe polarity. We report on the synthesis of high quality LaNiO$_3$/mLaAlO$_3$\npseudo cubic (111) superlattices on polar (111)-oriented LaAlO$_3$, the\nproposed complex oxide candidate for a topological insulating behavior.\nComprehensive X-Ray diffraction measurements, RHEED, and element specific\nresonant X-ray absorption spectroscopy affirm their high structural and\nchemical quality. The study offers an opportunity to fabricate interesting\ninterface and topology controlled (111) oriented superlattices based on\northo-nickelates."
    },
    {
        "anchor": "Nanoscale inhomogeneities: A new path toward high Curie temperature\n  ferromagnetism in diluted materials: Room temperature ferromagnetism has been one of the most sought after topics\nin today's emerging field of spintronics. It is strongly believed that defect-\nand inhomogeneity- free sample growth should be the optimal route for achieving\nroom-temperature ferromagnetism and huge efforts are made in order to grow\nsamples as \"clean\" as possible. However, until now, in the dilute regime it has\nbeen difficult to obtain Curie temperatures larger than that measured in well\nannealed samples of (Ga,Mn)As ($\\sim$190 K for 12% doping). In the present\nwork, we propose an innovative path to room-temperature ferromagnetism in\ndiluted magnetic semiconductors. We theoretically show that even a very small\nconcentration of nanoscale inhomogeneities can lead to a tremendous boost of\nthe critical temperatures: up to a 1600% increase compared to the homogeneous\ncase. In addition to a very detailed analysis, we also give a plausible\nexplanation for the wide variation of the critical temperatures observed in\n(Ga,Mn)N and provide a better understanding of the likely origin of very high\nCurie temperatures measured occasionally in some cases. The colossal increase\nof the ordering temperatures by nanoscale cluster inclusions should open up a\nnew direction toward the synthesis of materials relevant for spintronic\nfunctionalities.",
        "positive": "Self-organization of (001) cubic crystal surfaces: Self-organization on crystal surface is studied as a two dimensional spinodal\ndecomposition in presence of a surface stress. The elastic Green function is\ncalculated for a $(001)$ cubic crystal surface taking into account the crystal\nanisotropy. Numerical calculations show that the phase separation is driven by\nthe interplay between domain boundary energy and long range elastic\ninteractions. At late stage of the phase separation process, a steady state\nappears with different nanometric patterns according to the surface coverage\nand the crystal elastic constants."
    },
    {
        "anchor": "Anomalous vibrational effects in non-magnetic and magnetic Heusler\n  alloys: First-principles calculations are used in order to investigate phonon\nanomalies in non-magnetic and magnetic Heusler alloys. Phonon dispersions for\nseveral systems in their cubic L2$\\mathrm{_1}$ structure were obtained along\nthe [110] direction. We consider compounds which exhibit phonon instabilities\nand compare them with their stable counterparts. The analysis of the electronic\nstructure allows us to identify the characteristic features leading to\nstructural instabilities. The phonon dispersions of the unstable compounds show\nthat, while the acoustic modes tend to soften, the optical modes disperse in a\nway which is significantly different from that of the stable structures. The\noptical modes that appear to disperse at anomalously low frequencies are Raman\nactive, which is considered an indication of a stronger polarizability of the\nunstable systems. We show that phonon instability of the TA$_{2}$ mode in\nHeusler alloys is driven by interaction(repulsion) with the low energy optical\nvibrations. The optical modes show their unusual behavior due to covalent\ninteractions which are additional bonding features incommensurate with the\ndominating metallicity in Heusler compounds.",
        "positive": "A Noise-Robust Data Assimilation Method for Crystal Structure Prediction\n  Using Powder Diffraction Intensity: Crystal structure prediction for a given chemical composition has long been a\nchallenge in condensed-matter science. We have recently shown that experimental\npowder X-ray diffraction (XRD) data are helpful in a crystal structure search\nusing simulated annealing, even when they are insufficient for structure\ndetermination by themselves (N. Tsujimoto et al., Phys. Rev. Materials 2,\n053801 (2018)). In the method, the XRD data are assimilated into the simulation\nby adding a penalty function to the physical potential energy, where we used a\ncrystallinity-type penalty function defined by the difference between\nexperimental and simulated diffraction angles. To improve the success rate and\nnoise robustness, we introduce a correlation-coefficient-type penalty function\nadaptable to XRD data with significant experimental noise. We apply the new\npenalty function to SiO$_2$ coesite and $\\epsilon$-Zn(OH)$_2$ to determine its\neffectiveness in the data assimilation method."
    },
    {
        "anchor": "Anti-sites disordering suppression of the possible phase transition in\n  Mn2CrGa: Theoretical and experimental characterizations of Mn2CrGa compound in regard\nto the possibility of phase transformation have been carried out in this work.\nUnder a high ordering L21 structure, this compound has the potential to be a\nmartensite phase transition material. However, experimental results show a\nsevere disordering took place in this system, which forbids the occurring of\nthe phase transition. This work provides important reference for the design of\nnew phase transition materials in Heusler alloys.",
        "positive": "Self-consistent modelling of nonlinear dynamic ESM microscopy in mixed\n  ionic-electronic conductors: Dynamic Electrochemical Strain Microscopy (ESM) response of mixed\nionic-electronic conductors is analysed in the framework of the Thomas-Fermi\nscreening theory and Vegard law with accounting of the steric effects. The\nemergence of dynamic charge waves and nonlinear deformation of the surface as\nresult of applying probing voltage is numerically explored. 2D maps of the\nstrain and concentration distribution across the mixed ionic-electronic\nconductor and bias-induced surface displacements for ESM microscopy were\ncalculated. Obtained numerical results can be of applied to quantify ESM\nresponse of Li-based solid electroytes, materials with resistive switching and\nelectroactive ferroelectric polymers, which are of potential interest for\nflexible and high-density non-volatile memory devices."
    },
    {
        "anchor": "Ultrafast electron localization and screening in a transition metal\n  dichalcogenide: The coupling of light to electrical charge carriers in semiconductors is the\nfoundation of many technological applications. Attosecond transient absorption\nspectroscopy measures simultaneously how excited electrons and the vacancies\nthey leave behind dynamically react to the applied optical fields. In compound\nsemiconductors, these dynamics can be probed via any of their atomic\nconstituents. Often, the atomic species forming the compound contribute\ncomparably to the relevant electronic properties of the material. One therefore\nexpects to observe similar dynamics, irrespective of the choice of atomic\nspecies via which it is probed. Here, we show in the two-dimensional transition\nmetal dichalcogenide semiconductor $MoSe_2$, that through a selenium-based\ntransition we observe charge carriers acting independently from each other,\nwhile when probed through molybdenum, the collective, many-body motion of the\ncarriers dominates. Such unexpectedly contrasting behavior can be traced back\nto a strong localization of electrons around molybdenum atoms following\nabsorption of light, which modifies the local fields acting on the carriers. We\nshow that similar behavior in elemental titanium metal carries over to\ntransition metal-containing compounds and is expected to play an essential role\nfor a wide range of such materials. Knowledge of independent particle and\ncollective response is essential for fully understanding these materials.",
        "positive": "Local structural ordering determines the mechanical damage tolerance of\n  amorphous grain boundary complexions: Amorphous grain boundary complexions act as toughening features within a\nmicrostructure because they can absorb dislocations more efficiently than\ntraditional grain boundaries. This toughening effect should be a strong\nfunction of the local internal structure of the complexion, which has recently\nbeen shown to be determined by grain boundary crystallography. To test this\nhypothesis, molecular dynamics are used here to simulate dislocation absorption\nand damage nucleation for complexions with different distributions of\nstructural short-range order. The complexion with a more disordered structure\naway from the dislocation absorption site is actually found to better resist\ncrack nucleation, as damage tolerance requires delocalized deformation and the\noperation of shear-transformation zones through the complexion thickness. The\nmore damage tolerant complexion accommodates plastic strain efficiently within\nthe entire complexion, providing the key mechanistic insight that local\npatterning and asymmetry of structural short-range order controls the\ntoughening effect of amorphous complexions."
    },
    {
        "anchor": "Scalable, Non-Invasive Glucose Sensor Based on Boronic Acid\n  Functionalized Carbon Nanotube Transistors: We developed a scalable, label-free all-electronic sensor for D-glucose based\non a carbon nanotube transistor functionalized with pyrene-1-boronic acid. This\nsensor responds to glucose in the range 1 uM - 100 mM, which includes typical\nglucose concentrations in human blood and saliva. Control experiments establish\nthat functionalization with the boronic acid provides high sensitivity and\nselectivity for glucose. The devices show better sensitivity than commercial\nblood glucose meters and could represent a general strategy to bloodless\nglucose monitoring by detecting low concentrations of glucose in saliva.",
        "positive": "Bismuth-doped Ga2O3 as candidate for p-type transparent conducting\n  material: Gallium oxide (Ga2O3) is a wide-band-gap semiconductor promising for UV\nsensors and high power transistor applications, with Baliga's figure of merit\nthat far exceeds those of GaN and SiC, second only to diamond. Engineering its\nband structure through alloying will broaden its range of applications. Using\nhybrid density functional calculations we study the effects on adding Bi to\nGa2O3. While in III-V semiconductors, such as GaAs and InAs, Bi tend to\nsubstitute on the pnictide site, we find that in Ga2O3, Bi prefers to\nsubstitute on the Ga site, resulting in dilute (Ga_{1-x}Bi_{x})2O3 alloys with\nunique electronic structure properties. Adding a few percent of Bi reduces the\nband gap of Ga2O3 by introducing an intermediate valence band that is\nsignificantly higher in energy than the valence band of the host material. This\nintermediate valence band is composed mainly of Bi 6s and O 2p orbitals, and it\nis sufficiently high in energy to provide opportunity for p-type doping."
    },
    {
        "anchor": "Wave-function inspired density functional applied to the H$_2$/H$_2^+$\n  challenge: We start from the Bethe-Goldstone equation (BGE) to derive a simple\norbital-dependent correlation functional -- BGE2 -- which terminates the BGE\nexpansion at the second-order, but retains the self-consistent coupling of\nelectron-pair orrelations. We demonstrate that BGE2 is size consistent and\none-electron \"self-correlation\" free. The electron-pair correlation coupling\nensures the correct H$_2$ dissociation limit and gives a finite correlation\nenergy for any system even if it has a no energy gap. BGE2 provides a good\ndescription of both H$_2$ and H$_2^+$ dissociation, which is regarded as a\ngreat challenge in density functional theory (DFT). We illustrate the behavior\nof BGE2 analytically by considering H$_2$ in a minimal basis. Our analysis\nshows that BGE2 captures essential features of the adiabatic connection path\nthat current state-of-the-art DFT approximations do not.",
        "positive": "Ultrafast entropy production in pump-probe experiments: The ultrafast control of materials has opened the possibility to investigate\nnon-equilibrium states of matter with striking properties, such as transient\nsuperconductivity and ferroelectricity, ultrafast magnetization and\ndemagnetization, as well as Floquet engineering. The characterization of the\nultrafast thermodynamic properties within the material is key for their control\nand design. Here, we develop the ultrafast stochastic thermodynamics for\nlaser-excited phonons. We calculate the entropy production and heat absorbed\nfrom experimental data for single phonon modes of driven materials from\ntime-resolved X-ray scattering experiments where the crystal is excited by a\nlaser pulse. The spectral entropy production is calculated for SrTiO$_3$ and\nKTaO$_3$ for different temperatures and reveals a striking relation with the\npower spectrum of the displacement-displacement correlation function by\ninducing a broad peak beside the eigenmode-resonance."
    },
    {
        "anchor": "Precise response functions in all-electron methods: Application to the\n  optimized-effective-potential approach: The optimized-effective-potential (OEP) method is a special technique to\nconstruct local Kohn-Sham potentials from general orbital-dependent energy\nfunctionals. In a recent publication [M. Betzinger, C. Friedrich, S. Bl\\\"ugel,\nA. G\\\"orling, Phys. Rev. B 83, 045105 (2011)] we showed that uneconomically\nlarge basis sets were required to obtain a smooth local potential without\nspurious oscillations within the full-potential linearized augmented-plane-wave\nmethod (FLAPW). This could be attributed to the slow convergence behavior of\nthe density response function. In this paper, we derive an incomplete-basis-set\ncorrection for the response, which consists of two terms: (1) a correction that\nis formally similar to the Pulay correction in atomic-force calculations and\n(2) a numerically more important basis response term originating from the\npotential dependence of the basis functions. The basis response term is\nconstructed from the solutions of radial Sternheimer equations in the\nmuffin-tin spheres. With these corrections the local potential converges at\nmuch smaller basis sets, at much fewer states, and its construction becomes\nnumerically very stable. We analyze the improvements for rock-salt ScN and\nreport results for BN, AlN, and GaN, as well as the perovskites CaTiO3, SrTiO3,\nand BaTiO3. The incomplete-basis-set correction can be applied to other\nelectronic-structure methods with potential-dependent basis sets and opens the\nperspective to investigate a broad spectrum of problems in theoretical\nsolid-state physics that involve response functions.",
        "positive": "Microstructure dependence of low-temperature elastic properties in\n  amorphous diamond-like carbon films: We have studied the internal friction and the relative change in the speed of\nsound of amorphous diamond-like carbon films prepared by pulsed-laser\ndeposition from 0.3 K to room temperature. Like the most of amorphous solids,\nthe internal friction below 10 K exhibits a temperature independent plateau.\nThe values of the internal friction plateau, however, are slightly below the\nuniversal ``glassy range'' where the internal frictions of almost all amorphous\nsolids lie. Similar observations have been made in our earlier studies in the\nthin films of amorphous silicon and amorphous germanium, and the behavior could\nbe well accounted for by the existence of the low-energy atomic tunneling\nstates. In this work, we have varied the concentration of sp^3 versus sp^2\ncarbon atoms by increasing laser fluence from 1.5 to 30 J/cm^2. Our results\nshow that both the internal friction and the speed of sound have a nonmonotonic\ndependence on sp^3/sp^2 ratio with the values of the internal friction plateau\nvarying between 6x10^-5 and 1.1x10^-4. We explain our findings as a result of a\npossible competition between the increase of atomic bonding and the increase of\ninternal strain in the films, both of which are important in determining the\ntunneling states in amorphous solids. In contrast, no significant dependence of\nlaser fluence is found in shear moduli of the films, which vary between 220 and\n250 GPa. The temperature dependence of the relative change in speed of sound,\nalthough it shows a similar nonmonotonic dependence on laser fluence as the\ninternal friction, differs from those found in thin films of amorphous silicon\nand amorphous germanium, which we explain as having the same origin as the\nanomalous behavior recently observed in the speed of sound of thin\nnanocrystalline diamond films."
    },
    {
        "anchor": "The structure and phase stability of CO adsorbates on Rh(110): The structure of CO adsorbates on the Rh(110) surface is studied at full\ncoverage using first-principles techniques. The relative energies of different\nadsorbate geometries are determined by means of accurate structure\noptimizations. In agreement with experiments, we find that a p2mg(2x1) 2CO\nstructure is the most stable. The CO molecules sit on the short-bridge site\n(carbon below) with the molecular axis slightly tilted off the surface normal,\nalong the (001) direction. Configurations corresponding to different\ndistributions of tilt angles are mapped onto an anisotropic 2D Ising model\nwhose parameters are extracted from our ab-initio calculations. We find that an\norder-disorder phase-transition occurs at a temperature T_c=350 K.",
        "positive": "Epitaxial strain adaption in chemically disordered FeRh thin films: Strain and strain adaption mechanisms in modern functional materials are of\ncrucial importance for their performance. Understanding these mechanisms will\nadvance innovative approaches for material properties engineering. Here we\nstudy the strain adaption mechanism in a thin film model system as function of\nepitaxial strain. Chemically disordered FeRh thin films are deposited on W-V\nbuffer layers, which allow for large variation of the preset lattice constants,\ne.g. epitaxial boundary condition. It is shown by means of high resolution\nX-ray reciprocal space maps and transmission electron microscopy that the\nsystem reacts with a tilting mechanism of the structural units in order to\nadapt to the lattice constants of the buffer layer. This response explained by\ndensity functional theory calculations, which evidence an energetic minimum for\nstructures with a distortion of c/a =0.87. The experimentally observed tilting\nmechanism is induced by this energy gain and allows the system to remain in the\nmost favorable structure. In general, it is shown that the use of epitaxial\nmodel heterostructures consisting of alloy buffer layers of fully miscible\nelements and the functional material of interest allows to study strain\nadaption behaviors in great detail. This approach makes even small secondary\neffects observable, such as the directional tilting of the structural domains\nidentified in the present case study."
    },
    {
        "anchor": "Review on phase transformations, fracture, chemical reactions, and other\n  structural changes in inelastic materials: Review of selected fundamental topics on the interaction between phase\ntransformations, fracture, and other structural changes in inelastic materials\nis presented. It mostly focuses on the concepts developed in the author's group\nover last three decades and numerous papers that affected us. It includes a\ngeneral thermodynamic and kinetic theories with sharp interfaces and within\nphase field approach. Numerous analytical (even at large strains) and numerical\nsolutions illustrate the main features of the developed theories and their\napplication to the real phenomena. Coherent, semicoherent, and noncoherent\ninterfaces, as well as interfaces with decohesion and with intermediate liquid\n(disordered) phase are discussed. Importance of the surface- and scale-induced\nphenomena on interaction between phase transformation with fracture and\ndislocations as well as inheritance of dislocations and plastic strains is\ndemonstrated. Some nontrivial phenomena, like solid-solid phase transformations\nvia intermediate (virtual) melt, virtual melting as a new mechanism of plastic\ndeformation and stress relaxation under high strain rate loading, and phase\ntransformations and chemical reactions induced by plastic shear under high\npressure are discussed and modeled.",
        "positive": "First-principles study of the structural energetics of PdTi and PtTi: The structural energetics of PdTi and PtTi have been studied using\nfirst-principles density-functional theory with pseudopotentials and a\nplane-wave basis. We predict that in both materials, the experimentally\nreported orthorhombic $B19$ phase will undergo a low-temperature phase\ntransition to a monoclinic $B19'$ ground state. Within a soft-mode framework,\nwe relate the $B19$ structure to the cubic $B2$ structure, observed at high\ntemperature, and the $B19'$ structure to $B19$ via phonon modes strongly\ncoupled to strain. In contrast to NiTi, the $B19$ structure is extremely close\nto hcp. We draw on the analogy to the bcc-hcp transition to suggest likely\ntransition mechanisms in the present case."
    },
    {
        "anchor": "Free standing membranes to study the optical properties of anodic TiO2\n  nanotube layers: In the present work we investigate various optical properties (such as light\nabsorption and reflectance) of anodic TiO2 nanotubes layers directly\ntransferred as self-standing membranes onto quartz substrates. This allows\ninvestigation in a transmission geometry which provides significantly more\nreliable data than measurements on the metallic Ti substrate. Light\ntransmission and reflectance measurements were carried out for layers of\nthicknesses varying from 1.8 to 50 micrometer, and the layers were investigated\nin their amorphous and crystalline form. A series of wavelength-dependent light\nattenuation coefficients are extrapolated and found to match the photocurrent\nvs. irradiation wavelength behavior. However, a feature specific to anodic\nnanotubes is that their intrinsic carbon content causes a sub-bandgap response\nthat is proportional to the carbon contamination content in the TiO2 nanotubes.\nOverall the extracted data provide valuable basis and understanding for the\ndesign of photo-electrochemical devices based on TiO2 nanotubes.",
        "positive": "Ultrafast optical melting of trimer superstructure in layered 1T'-TaTe2: Quasi-two-dimensional transition-metal dichalcogenides are a key platform for\nexploring emergent nanoscale phenomena arising from complex interactions.\nAccess to the underlying degrees-of-freedom on their natural time scales\nmotivates the use of advanced ultrafast probes sensitive to self-organised\natomic-scale patterns. Here, we report the first ultrafast investigation of\nTaTe2, which exhibits unique charge and lattice trimer order characterised by a\ntransition upon cooling from stripe-like chains into a $(3 \\times 3)$\nsuperstructure of trimer clusters. Utilising MeV-scale ultrafast electron\ndiffraction, we capture the photo-induced TaTe2 structural dynamics -- exposing\na rapid $\\approx\\!1.4$ ps melting of its low-temperature ordered state followed\nby recovery via thermalisation into a hot cluster superstructure.\nDensity-functional calculations indicate that the initial quench is triggered\nby intra-trimer Ta charge transfer which destabilises the clusters, unlike\nmelting of charge density waves in other TaX2 compounds. Our work paves the way\nfor further exploration and ultimately rapid optical and electronic\nmanipulation of trimer superstructures."
    },
    {
        "anchor": "Scale-invariant Machine-learning Model Accelerates the Discovery of\n  Quaternary Chalcogenides with Ultralow Lattice Thermal Conductivity: Intrinsically low lattice thermal conductivity ($\\kappa_l$) is a desired\nrequirement in many crystalline solids such as thermal barrier coatings and\nthermoelectrics. Here, we design an advanced machine-learning (ML) model based\non crystal graph convolutional neural network that is insensitive to volumes\n(i.e., scale) of the input crystal structures to discover novel quaternary\nchalcogenides, AMM'Q$_3$ (A/M/M'=alkali, alkaline-earth, post-transition\nmetals, lanthanides, Q=chalcogens). Upon screening the thermodynamic stability\nof $\\sim$ 1 million compounds using the ML model iteratively and performing\ndensity functional theory (DFT) calculations for a small fraction of compounds,\nwe discover 99 compounds that are validated to be stable in DFT. Taking several\nDFT-stable compounds, we calculate their $\\kappa_l$ using phonon-Boltzmann\ntransport equation, which reveals ultralow-$\\kappa_l$ ($<$ 2 Wm$^{-1}$K$^{-1}$\nat room-temperature) due to their soft elasticity and strong phonon\nanharmonicity. Our work demonstrates the high-efficiency of scale-invariant ML\nmodel in predicting novel compounds and presents experimental research\nopportunities with these new compounds.",
        "positive": "Anomalous electronic conductance in quasicrystals: Generic quantum interference effects occuring in 1D-quasicrystals are\nreviewed with emphasis on the joint effect of phason disorder on electronic\nlocalization and propagation modes. In close conjunction with properties of\nreal materials, the contributions of quantum interferences in several regimes\nclose to the metal insulator transition are outlined."
    },
    {
        "anchor": "Diffusion-free ultrafast carrier dynamics in silicon nano-pillars: We have investigated ultrafast carriers dynamics in crystalline silicon\nnano-pillars structure using a pump-probe reflectivity method with 800 nm, 150\nfs laser pulses and fluence in the range of {17 - 170} mJ/cm^2. Dimensions of\nthe structure allow us to eliminate contribution from the diffusion process to\nthe relaxation dynamics of the excited carriers. Strong intensity-dependent\ntime-resolved reflectivity change, \\Delta R(\\tau_d), was monitored in the\nsubmelting regime. At strong pumping \\Delta R(\\tau_d) can reach up to 8%, a\nseveral times higher than for a bulk silicon. From the measurements we deduced\nrecombination time of up to 10 ns at carriers density of ~1 x 10^20 cm^-3,\nwhile electron-phonon interaction occurs during 350-400 fs and it is\nindependent of the concentration.",
        "positive": "Temperature-driven changes in the Fermi surface of graphite: We report on temperature-dependent size and anisotropy of the Fermi pockets\nin graphite revealed by magnetotransport measurements. The magnetoresistances\nobtained in fields along the c-axis obey an extended Kohler's rule, with the\ncarrier density following prediction of a temperature-dependent Fermi energy,\nindicating a change in the Fermi pocket size with temperature. The\nangle-dependent magnetoresistivities at a given temperature exhibit a scaling\nbehavior. The scaling factor that reflects the anisotropy of the Fermi surface\nis also found to vary with temperature. Our results demonstrate that\ntemperature-driven changes in Fermi surface can be ubiquitous and need to be\nconsidered in understanding the temperature-dependent carrier density and\nmagnetoresistance anisotropy in semimetals."
    },
    {
        "anchor": "Momentum average approximation for models with boson-modulated hopping:\n  Role of closed loops in the dynamical generation of a finite quasiparticle\n  mass: We generalize the momentum average approximation to study the properties of\nsingle polarons in models with boson affected hopping, where the fermion-boson\nscattering depends explicitly on both the fermion's and the boson's momentum.\nAs a specific example, we investigate the Edwards fermion-boson model in both\none and two dimensions. In one dimension, this allows us to compare our results\nwith exact diagonalization results, to validate the accuracy of our\napproximation. The generalization to two-dimensional lattices allows us to\ncalculate the polaron's quasiparticle weight and dispersion throughout the\nBrillouin zone and to demonstrate the importance of Trugman loops in generating\na finite effective mass even when the free fermion has an infinite mass.",
        "positive": "A Prompt-Engineered Large Language Model, Deep Learning Workflow for\n  Materials Classification: With the advent of ChatGPT, large language models (LLMs) have demonstrated\nconsiderable progress across a wide array of domains. Owing to the extensive\nnumber of parameters and training data in LLMs, these models inherently\nencompass an expansive and comprehensive materials knowledge database, far\nexceeding the capabilities of individual researcher. Nonetheless, devising\nmethods to harness the knowledge embedded within LLMs for the design and\ndiscovery of novel materials remains a formidable challenge. In this study, we\nintroduce a general approach for addressing materials classification problems,\nwhich incorporates LLMs, prompt engineering, and deep learning algorithms.\nUtilizing a dataset of metallic glasses as a case study, our methodology\nachieved an improvement of up to 463% in prediction accuracy compared to\nconventional classification models. These findings underscore the potential of\nleveraging textual knowledge generated by LLMs for materials especially with\nsparse datasets, thereby promoting innovation in materials discovery and\ndesign."
    },
    {
        "anchor": "Optimization and Validation of a Deep Learning CuZr Atomistic Potential:\n  Robust Applications for Crystalline and Amorphous Phases with near-DFT\n  Accuracy: We show that a deep-learning neural network potential (DP) based on density\nfunctional theory (DFT) calculations can well describe Cu-Zr materials, an\nexample of a binary alloy system that can coexist in several ordered\nintermetallics and as an amorphous phase. The complex phase diagram for Cu-Zr\nmakes it a challenging system for traditional atomistic force-fields that fail\nto describe well the different properties and phases. Instead, we show that a\nDP approach using a large database with ~300k configurations can render results\ngenerally on par with DFT. The training set includes configurations of pristine\nand bulk elementary metals and intermetallics in the liquid and solid phases in\naddition to slab and amorphous configurations. The DP model was validated by\ncomparing bulk properties such as lattice constants, elastic constants, bulk\nmoduli, phonon spectra, surface energies to DFT values for identical\nstructures. Further, we contrast the DP results with values obtained using\nwell-established two embedded atom method potentials. Overall, our DP potential\nprovides near DFT accuracy for the different Cu-Zr phases but with a fraction\nof its computational cost, thus enabling accurate computations of realistic\natomistic models especially for the amorphous phase.",
        "positive": "Epitaxial Graphene on Silicon toward Graphene-Silicon Fusion Electronics: Graphene is a promising contender to succeed the throne of silicon in\nelectronics. To this goal, large-scale epitaxial growth of graphene on\nsubstrates should be developed. Among various methods along this line,\nepitaxial growth of graphene on SiC substrates by thermal decomposition of\nsurface layers has proved itself quite satisfactory both in quality and in\nprocess reliability. Even modulation of structural and hence electronic\nproperties of graphene is possible by tuning the graphene/SiC interface\nstructure. The challenges for this graphene-on-SiC technology, however, are the\nabdication of the well-established Si technologies and the high production cost\nof the SiC bulk crystals. Here, we demonstrate that formation of epitaxial\ngraphene on silicon substrate is possible, by graphitizing epitaxial SiC thin\nfilms formed on silicon substrates. This graphene-on-silicon (GOS) method\nenables us to form a large-area film of well-ordered sp2 carbon networks on Si\nsubstrates and to fabricate electronic devices based on the structure."
    },
    {
        "anchor": "Photo-physical and nonlinear-optical properties of a new polymer:\n  hydroxylated pyridyl para-phenylene: Photo-physical and nonlinear-optical properties of a new amphiphilic\nconjugated polymer: hydroxylated pyridyl para-phenylene (Py-PhPPP) both in\nCH2Cl2 solution and in thin films have been investigated. By using Z-scan\ntechnique with nanosecond laser pulses of wavelengths ranging from 430 to 600\nnm, the large nonlinear absorption and refraction have been determined in terms\nof the effective third-order, nonlinear-optical susceptibilities. These Z-scans\nreveal that the nonlinear absorption alters from reverse saturable absorption\nto saturable absorption at wavelength of ~ 540 nm. Similarly, alteration from\nself-defocusing to self-focusing manifests itself at the same wavelength. The\noptical limiting performance of Py-PhPPP in solution is superior to toluene\nsolution of [60]fullerene (C60) at 532 nm. Both UV-visible absorption spectra\nand photoluminescence (PL) spectra show concentration dependence. The PL\nspectra also depend on excitation wavelengths. These evidences suggest that the\naggregate formation should play an important role in the nonlinear-optical\nproperties of the new polymer. We attribute the reverse saturable absorption in\nthe region of blue and green wavelengths mainly to intra-chain, triplet-triplet\nabsorption while the absorption bleaching at longer wavelengths is due to\nsaturation in the absorption band induced by the aggregates.",
        "positive": "Early stages of polycrystalline diamond deposition: Laser reflectance at\n  substrates with growing nanodiamonds: The chemical vapor deposition of polycrystalline diamond (PCD) films is\ntypically done on substrates seeded with diamond nanoparticles. Specular laser\nreflectance and a continuous film model have been used to monitor the thickness\nof these films during their deposition. However, most seeds are isolated during\nthe early stages of the deposition, which questions the utility of applying\nsuch a continuous film model for monitoring deposition before film formation.\nIn this work, we present a model based on the Rayleigh theory of scattering for\nlaser reflectance at substrates with growing nanodiamonds to capture the early\nstages of PCD deposition. The reflectance behavior predicted by our model\ndiffers from that of a continuous film, which is well-described by the\ncontinuous film model. This difference enlarges as the seed density used in our\nmodel decreases. We verify this trend experimentally by depositing diamond\nunder identical conditions on substrates with various seed densities. A\nrelation derived from our model is used to fit reflectance data from which seed\ndensities are obtained that are proportional to those found with electron\nmicroscopy. We also show that relying on the continuous film model for\ndescribing the early stages of deposition can result in falsely deducing the\nexistence of incubation, and that the continuous film model can be used safely\nbeyond the early stages of deposition. Based on these findings, we delineate a\nrobust method for obtaining growth rates and incubation periods from\nreflectance measurements. This work may also advance the general understanding\nof nanoparticle growth and formation."
    },
    {
        "anchor": "Influence of homo-buffer layer on stress control of sputtered\n  (Ba0.45,Sr0.55)TiO3 thin films on Pt-Si: To engineer strain relaxation of sputtered BST thin films on Pt-Si wafers,\nhomo-buffer layer method was applied to eliminate Pt hillock formation. Thin\nBST homo-buffer layers were deposited at room temperature and subsequently the\nmain BST layer was deposited at 650{\\deg}C, Pt hillock free BST films were\nobtained with homo-buffer thickness above 5 nm. Relatively good electrical\nproperties were obtained for BST thin films with 15 and 25 nm homo-buffer layer\n(T= 30 % at 5V and tan {\\delta}= 0.018).",
        "positive": "Ultrafast carrier relaxation and its Pauli drag in photo-enhanced\n  melting of solids: Ultrafast light-matter interaction is a powerful tool for the study of\nsolids. Upon laser excitation, carrier multiplication and lattice acceleration\nbeyond thermal velocity can occur, as a result of far-from-equilibrium carrier\nrelaxation. The roles of electron-electron and electron-phonon scatterings are\nidentified by first-principles dynamic simulations, from which a unified phase\ndiagram emerges. It not only explains the experimentally-observed \"inertial\"\nmelting but also predicts abnormal damping by Pauli Exclusion Principle with a\nnew perspective on ultrahigh-intensity laser applications."
    },
    {
        "anchor": "Electrospun light-emitting nanofibers as building blocks for photonics\n  and electronics: Nanomaterials made of active fibers have the potential to become new\nfunctional components of light-emitting sources in the visible and near-IR\nrange, lasers, and electronic devices",
        "positive": "Resistive switching in ferroelectric BiFeO3 by 1.7 eV change of the\n  Schottky barrier height: Using metal-ferroelectric junctions as switchable diodes was proposed several\ndecades ago. This was shown to actually work in PbZr(1-x)TixO3 (PZT) by Blom et\nal. [P.W. M. Blom et al., Phys. Rev. Lett. 73, 2107 (1994)], who reported\nswitching in the rectification direction and changes of the current of about 2\norders of magnitude upon switching the polarization direction of the\nferroelectric layer. This form of resistive switching enables the read out of a\nferroelectric memory state at higher speed compared to the capacitive design,\nwithout destroying the information in each reading cycle. Recently, Jiang and\ncoworkers have shown that these Schottky barrier effects are enormous in\nBiFeO3, giving thousand times more switched charge than found by in PZT [A.Q.\nJiang. et al., Adv. Mat. 23, 1277 (2011)]. Here, by performing local\nconductivity measurements, we attribute this to a large change of the Schottky\nbarrier height between the as-grown, down-polarized domains and the\nup-polarized domains. These measurements allow to estimate the relative effect\nof polarization charges and screening charges on the conduction through the\nferroelectric."
    },
    {
        "anchor": "Ordered array of $\u03c9$ particles in $\u03b2$-Ti matrix studied by\n  small-angle X-ray scattering: Nanosized particles of $\\omega$ phase in a $\\beta$-Ti alloy were investigated\nby small-angle X-ray scattering using synchrotron radiation. We demonstrated\nthat the particles are spontaneously weakly ordered in a three-dimensional\ncubic array along the $\\langle 100\\rangle$-directions in the $\\beta$-Ti matrix.\nThe small-angle scattering data fit well to a three-dimensional\nshort-range-order model; from the fit we determined the evolution of the mean\nparticle size and mean distance between particles during ageing. The\nself-ordering of the particles is explained by elastic interaction between the\nparticles, since the relative positions of the particles coincide with local\nminima of the interaction energy. We performed numerical Monte Carlo simulation\nof the particle ordering and we obtained a good agreement with the experimental\ndata.",
        "positive": "On the derivation of the magnetocaloric properties in ferrimagnetic\n  spinel Mn3O4: Large magnetocaloric effect has been observed in Mn3O4 around its\nferrimagnetic transition at TN = 42.75 K. Field-induced isothermal entropy\nchanges (\\DeltaS) were derived from both magnetic and calorimetric techniques.\nThe maximum |\\DeltaS| and adiabatic temperature change ({\\Delta}Tad) at TN are\n11 J kg-1 K-1 and 1.9 K, respectively, for a magnetic field change of 20 kOe.\nMoreover, it is found that the complex magnetic phase transitions taking place\nbelow TN produce additional -but smaller- features on \\DeltaS(T)."
    },
    {
        "anchor": "Statistical mechanics of interacting fiber bundles: We consider quasistatic fiber bundle models with interactions. Classical load\nsharing rules are considered, i.e. local, global or decaying as a power-law of\ndistance. All fibers are identically elastic, initially intact, and break at a\nrandom threshold picked from a quenched disorder (q.d.) distribution. We are\ninterested in the probability distribution of configurations of broken fibers\nat a given elongation, averaged over all possible realizations of the\nunderlying q.d.. This distribution is accessed by mapping the threshold set\nspace onto the configurational space, each path corresponding to the evolution\nof a bundle corresponding to a realized q.d.. Using a perturbative approach\nallows to obtain this distribution to leading order in the interactions. This\nmaps this system onto classical statistical mechanics models, i.e. percolation,\nstandard or generalized Ising models depending on the range of the interactions\nchosen in the load sharing rule. This relates such q.d. based systems to\nstandard classical mechanics, which allows to derive observables of the system,\nas e.g. correlation lengths. The thermodynamic parameters formally equivalent\nto temperature and chemical potential, are functions of the externally imposed\ndeformation, depending on the load sharing rule and the choice of the q.d.\ndistribution.",
        "positive": "Formation of iron nitride thin films with Al and Ti additives: In this work we investigate the process of iron nitride (Fe-N) phase\nformation using 2 at.% Al or 2 at.% Ti as additives. The samples were prepared\nwith a magnetron sputtering technique using different amount of nitrogen during\nthe deposition process. The nitrogen partial pressure (\\pn) was varied between\n0-50% (rest Argon) and the targets of pure Fe, [Fe+Ti] and [Fe+Al] were\nsputtered. The addition of small amount of Ti or Al results in improved\nsoft-magnetic properties when sputtered using \\pn $\\leq$ 10\\p. When \\pn is\nincreased to 50\\p non-magnetic Fe-N phases are formed. We found that iron\nmononitride (FeN) phases (N at% $\\sim$50) are formed with Al or Ti addition at\n\\pn =50% whereas in absence of such addition \\eFeN phases (N\\pat$\\sim$30) are\nformed. It was found that the overall nitrogen content can be increased\nsignificantly with Al or Ti additions. On the basis of obtained result we\npropose a mechanism describing formation of Fe-N phases Al and Ti additives."
    },
    {
        "anchor": "\"Pudding mold\" band drives large thermopower in Na$_x$CoO$_2$: In the present study, we pin down the origin of the coexistence of the large\nthermopower and the large conductivity in Na$_x$CoO$_2$. It is revealed that\nnot just the density of states (DOS), the effective mass, nor the band width,\nbut the peculiar {\\it shape} of the $a_{1g}$ band referred to as the \"pudding\nmold\" type, which consists of a dispersive portion and a somewhat flat portion,\nis playing an important role in this phenomenon. The present study provides a\nnew guiding principle for designing good thermoelectric materials.",
        "positive": "Ab initio study of ferroelectric domain walls in PbTiO3: We have investigated the atomistic structure of the 180-degree and 90-degree\ndomain boundaries in the ferroelectric perovskite compound PbTiO3 using a\nfirst-principles ultrasoft-pseudopotential approach. For each case we have\ncomputed the position, thickness and creation energy of the domain walls, and\nan estimate of the barrier height for their motion has been obtained. We find\nboth kinds of domain walls to be very narrow with a similar width of the order\nof one to two lattice constants. The energy of the 90-dergree domain wall is\ncalculated to be 35 mJ/m^2, about a factor of four lower than the energy of its\n180-degree counterpart, and only a miniscule barrier for its motion is found.\nAs a surprising feature we detected a small offset of 0.15-0.2 eV in the\nelectrostatic potential across the 90-degree domain wall."
    },
    {
        "anchor": "Raman scattering studies of the lateral Mn distribution in MBE-grown\n  Ga1-xMnxN epilayers: Recent interest in very thin single phase Ga1-xMnxN dilute magnetic layers\nincreased needs for precise, non-destructive, and relatively fast\ncharacterization methods with key issues being the macroscopic lateral Mn\ndistribution and the absolute values of Mn concentration x. We report on\nresonantly enhanced UV Raman scattering studies of high quality Ga1-xMnxN\nlayers grown on GaN templated sapphire by molecular beam epitaxy with 4 < x <\n9%. The main advantage of the UV excitation is the restriction of the light\npenetration depth to nearly a hundred nanometers, eliminating signal from the\nGaN buffer. Under this conditions we determine the dependence of the 1LO phonon\nfrequency on x, what allows for a fine mapping of its lateral distribution over\nthe entire surface of the samples. Our Raman scanning clearly confirms\nsubstantial lateral distribution of Mn atoms across the layer, which is radial\nwith respect to its center. From the established distributions in two\ndeliberately chosen layers the magnitude of the optimal growth temperature for\nmost efficient Mn atoms incorporation in epitaxial GaN has been confirmed. It\nis shown that the combination of the 1LO line width and its energy provides\nassessment of the crystalline quality of the investigated layers.",
        "positive": "Influence of the martensitic transformation kinetics on the\n  magnetocaloric effect in Ni-Mn-In: The inverse magnetocaloric effect (MCE) in Ni-Mn-based Heusler compounds\noccurs during the magnetostructural transition between low-temperature,\nlow-magnetization martensite and high-temperature, high-magnetization\naustenite. In this study, we analyze the metamagnetic transformation of a\n$Ni_{49.8}Mn_{35}In_{15.2}$ compound by simultaneous adiabatic temperature\nchange and strain measurements in pulsed magnetic fields up to 10 T. We observe\nan adiabatic temperature change of -10 K and a strain of -0.22 % when the\nreverse martensitic transition is fully induced at a starting temperature of\n285 K. By a variation of the magnetic field-sweep rates between 316 Ts$^{-1}$,\n865 Ts$^{-1}$ and 1850 Ts$^{-1}$, the transitional dynamics of the reverse\nmartensitic transformation have been investigated. Our experiments reveal an\napparent delay upon the end of the reverse martensitic transformation at field\nrates exceeding 865 Ts$^{-1}$ which is related to the annihilation of retained\nmartensite. As a consequence, the field hysteresis increases and higher fields\nare required to saturate the transition. In contrast, no time-dependent effects\non the onset of the reverse martensitic transformation were observed in the\nstudied field-sweep range. Our results demonstrate that kinetic effects in\nHeusler compounds strongly affect the magnetic cooling cycle, especially when\nutilising a multicaloric \"exploiting-hysteresis cycle\" where high magnetic\nfield-sweep rates are employed."
    },
    {
        "anchor": "Probing the nanoscale origin of strain and doping in graphene-hBN\n  heterostructures: We use confocal Raman microscopy and modified vector analysis methods to\ninvestigate the nanoscale origin of strain and carrier concentration in\nexfoliated graphene-hexagonal boron nitride (hBN) heterostructures on silicon\ndioxide (SiO2). Two types of heterostructures are studied: graphene on SiO2\npartially coved by hBN, and graphene fully encapsulated between two hBN flakes.\nWe extend the vector analysis methods to produce spatial maps of the strain and\ndoping variation across the heterostructures. This allows us to visualise and\ndirectly quantify the much-speculated effect of the environment on carrier\nconcentration as well as strain in graphene. Moreover, we demonstrate that\nvariations in strain and carrier concentration in graphene arise from nanoscale\nfeatures of the heterostructures such as fractures, folds and bubbles trapped\nbetween layers. For bubbles in hBN-encapsulated graphene, hydrostatic strain is\nshown to be greatest at bubble centres, whereas the maximum of carrier\nconcentration is localised at bubble edges. Raman spectroscopy is shown to be a\nnon-invasive tool for probing strain and doping in graphene, which could prove\nuseful for engineering of two-dimensional devices.",
        "positive": "Band structure calculations of Ti\\raisebox{-.2ex}{\\scriptsize 2}FeSn: a\n  new half-metallic compound: Within the framework of density functional theory, the electronic structure\nand magnetic properties have been studied for the\nTi\\raisebox{-.2ex}{\\scriptsize 2}FeSn full-Heusler compound. The ferromagnetic\nstate is found to be energetically more favorable than paramagnetic and\nantiferromagnetic states. The spin-polarized results show that\nTi\\raisebox{-.2ex}{\\scriptsize 2}FeSn compound has half-metallic ferromagnetic\ncharacter with a total spin moment of $2 \\mu_{B}$ and a band gap in the\nminority spin channel of 0.489 eV, at the equilibrium lattice constant a=6.342\nA."
    },
    {
        "anchor": "Phase diagram and piezoelectric response of (Ba1-xCax)(Zr0.1Ti0.9)O3\n  solid solution: We report the phase diagram of (Ba1-xCax)(Zr0.1Ti0.9)O3 solid solution. It is\nfound that substitution of smaller Ca ions for Ba ions can slightly increase\nthe cubic-tetragonal(T) para-ferroelectric phase transition temperature and\nstrongly decrease the T-orthorhombic (O) and O-rhombohedral (R) transition.\nThis unique ferroelectric phase evolution is attributed to Ca off-centering\neffects. More importantly, lowering of the T-O or O-R phase transitions allows\nus to prepare the piezoelectric ceramics with a strain response as high as\nS/E~800 pm/V (E=10 kV/cm) over a wide range of compositions with x~0.1 - 0. 18\nat room temperature, which may be interesting for piezoelectric applications.",
        "positive": "Optoelectronic Properties of Chalcogenide Perovskites by Many-Body\n  Perturbation Theory: Chalcogenide perovskites have emerged as non-toxic and stable photovoltaic\nmaterials, acting as an alternative to lead halide hybrid perovskites having\nsimilar optoelectronic properties. In the present work, we report the\nelectronic and optical properties of chalcogenide perovskites AZrS$_3$ (A=Ca,\nSr, Ba) by using the density functional theory (DFT) and many-body perturbation\ntheory (MBPT viz. G$_0$W$_0$ and BSE). This study includes excitonic analysis\nfor the aforementioned systems. The exciton binding energy (E$_\\textrm{B}$) is\nfound to be larger than that of the halide perovskites, as the ionic\ncontribution to dielectric screening is negligible in the former. We also\nobserve a more stable charge-separated polaronic state as compared to that of\nthe bound exciton. Finally, on the basis of direct gap and absorption\ncoefficient, the estimated spectroscopic limited maximum efficiency (SLME) of\nthe solar cells is large and suggests the applicability of these perovskites in\nphotovoltaics."
    },
    {
        "anchor": "Magnetic-Field Dependence of Novel Gap Behavior Related to the\n  Quantum-Size Effect: $^{195}$Pt-NMR measurements of Pt nanoparticles with a mean diameter of 4.0\nnm were performed in a high magnetic field of approximately $\\mu_0 H = 23.3$ T\nto investigate the low-temperature electronic state of the nanoparticles. The\ncharacteristic temperature $T^*$, below which the nuclear spin-lattice\nrelaxation rate $1/T_1$ deviates from the relaxation rate of the bulk, shows a\nmagnetic-field dependence. This dependence supports the theoretical prediction\nof the appearance of discrete energy levels.",
        "positive": "Ground-state structure of KNbO$_3$/KTaO$_3$ superlattices: Array of\n  nearly independent ferroelectrically ordered planes: Phonon spectra of the paraelectric phase, structure and distribution of\npolarization in the polar ground state, and energies of ferroelectrically and\nantiferroelectrically ordered phases were calculated for stress-free\n(KNbO$_3$)$_1$(KTaO$_3$)$_n$ superlattices ($n = {}$1--7) from first principles\nwithin the density-functional theory. Quasi-two-dimensional ferroelectric state\nwith the polarization localized in the KNbO$_3$ layer was revealed to be the\nground state for the superlattices with $n \\ge 2$. The interaction between\nthese polarized layers decreases exponentially with increasing the interlayer\ndistance, and the ground-state structure transforms to an array of nearly\nindependent ferroelectrically ordered planes at large $n$."
    },
    {
        "anchor": "The formation, ripening and stability of epitaxially strained island\n  arrays: We study the formation and evolution of coherent islands on lattice\nmismatched epitaxially strained films. Faceted islands form in films with\naniostropic surface tension. Under annealing, these islands ripen until a\nstable array is formed, with an island density which increases with film\nthickness. Under deposition, an island shape transition occurs, which leads to\na bimodal island size distribution. In films with isotropic surface tension we\nobserve continual ripening of islands above a certain film thickness. A stable\nwavy morphology is found in thinner films.",
        "positive": "NiOx passivation in perovskite solar cells: from surface reactivity to\n  device performance: Non-stoichiometric nickel oxide (NiOx) is the only metal oxide successfully\nused as hole transport material in p-i-n type perovskite solar cells (PSCs).\nIts favorable opto-electronic properties and facile large-scale preparation\nmethods are potentially relevant for future commercialization of PSCs, though\ncurrently low operational stability of PSCs containing NiOx hole transport\nlayers are reported. Poorly understood degradation reactions at the interface\nto the perovskite are seen as cause for the inferior stability and a variety of\ninterface passivation approaches have been shown to be effective in improving\nthe overall solar cell performance. To gain a better understanding of the\nprocesses happening at this interface, we systematically passivated possible\nspecific defects on NiOx with three different categories of organic/inorganic\ncompounds. The effects on the NiOx and the perovskite (MAPbI3) were\ninvestigated using x-ray photoelectron spectroscopy (XPS), X-ray diffraction\n(XRD), and scanning electron microscopy (SEM) where we find that the structural\nstability and film formation can be significantly affected. In combination with\nDensity Functional Theory (DFT) calculations, a likely origin of\nNiOx-perovskite degradation interactions is proposed. The surface passivated\nNiOx was incorporated into MAPbI3 based PSCs and its influence on overall\nperformance, particularly operational stability, was investigated by\ncurrent-voltage (J-V), impedance spectroscopy (IS), and open circuit voltage\ndecay (OCVD) measurements. Interestingly, we find that a superior structural\nstability due to an interface passivation must not relate to high operational\nstability. The discrepancy comes from the formation of excess ions at the\ninterface which negatively impacts all solar cell parameters."
    },
    {
        "anchor": "Creating topological polar structure in a nonpolar matter: Nontrivial topological structures offer rich playground in condensed matter\nphysics including fluid dynamics, superconductivity, and ferromagnetism, and\nthey promise alternative device configurations for post-Moore spintronics and\nelectronics. Indeed, magnetic skyrmions are actively pursued for high-density\ndata storage, while polar vortices with exotic negative capacitance may enable\nultralow power consumption in microelectronics. Following extensive\ninvestigations on a variety of magnetic textures including vortices, domain\nwalls and skyrmions in the past decades, studies on polar topologies have taken\noff in recent years, resulting in discoveries of closure domains, vortices, and\nskyrmions in ferroelectric materials. Nevertheless, the atomic-scale creation\nof topological polar structures is largely confined in a single ferroelectric\nsystem, PbTiO3 (PTO) with large polarization, casting doubt on the generality\nof polar topologies and limiting their potential applications. In this work, we\nsuccessfully create previously unrealized atomic-scale polar antivortices in\nthe nominally nonpolar SrTiO3 (STO), expanding the reaches of topological\nstructures and completing an important missing link in polar topologies. The\nwork shed considerable new insight into the formation of topological polar\nstructures, and offers guidance in searching for new polar textures.",
        "positive": "Interface evolution in phase transformation ruled by nucleation and\n  growth: An analytical model for the evolution of the boundary of the new phase in\ntransformations ruled by nucleation and growth is presented. Both homogeneous\nand heterogeneous nucleation have been considered: The former includes\ntransformations in 2D and 3D space and the latter nucleation and growth on flat\nsolid substrate. The theory is formulated for the general case of spatially\ncorrelated nuclei, arbitrary nucleation rate and power growth law of nuclei. In\nthe case of heterogeneous nucleation, spheroidal nuclei have been assumed and\nthe dependence of the kinetics on contact angle investigated. The validity of\nthe present approach is deemed through comparison with experimental data from\nliterature which also comprise oxide growth by ALD (Atomic Layer Deposition)\nmetal electrodeposition at solid substrate and alloy recrystallization."
    },
    {
        "anchor": "Estimation of Domain Size in Nano Ferroelectrics from NMR T1\n  Measurements: The spin lattice relaxation of I=3/2 quadrupolar spin system due to domain\nwalls in order-disorder ferroelectrics has been studied and a general method is\nproposed for the measurement of domain width in nano ferroelectrics. Based on\nthe fact that electric polarization undergoes spiral orientation as one moves\nfrom one domain to the other, it is assumed that at low temperatures the spins\nat and near domain walls undergo relaxation due to possible easy reorientation\nof electric polarization in domain walls even though such a relaxation in the\nmain body of the domain has almost ceased. The spins present inside the domain\nundergo relaxation through transfer of magnetization to the domain walls\nthrough a spin diffusion process by nearest neighbour interaction. Rate\nequations for spin populations are formed by representing the ferroelectric\ndomain by a one-dimensional chain of equidistant spins having dipolar coupling.\nSpin populations are calculated as a function of time for different ratios of\nquadrupolar to dipolar transition probabilities for a sample subjected to\nselective rf pulse. Expression for spin- lattice relaxation time T1 is derived\nin terms of domain width and ratio of quadrupolar to dipolar transition\nprobabilities. It is found that the domain width can be estimated provided the\nvalue of spin lattice relaxation time T1 is known for the corresponding crystal\nwith normal sized grains. The results are quite general and can be applied to\nany order disorder ferroelectric with nano sized domains and having spin I=3/2\nnuclei.",
        "positive": "First-principles study of phase stability of Gd-doped EuO and EuS: Phase diagrams of isoelectronic Eu$_{1-x}$Gd$_x$O and Eu$_{1-x}$Gd$_{x}$S\nquasi-binary alloy systems are constructed using first-principles calculations\ncombined with the standard cluster expansion approach and Monte-Carlo\nsimulations. The oxide system has a wide miscibility gap on the Gd-rich side\nbut forms ordered compounds on the Eu-rich side, exhibiting a deep asymmetric\nconvex hull in the formation enthalpy diagram. The sulfide system has no stable\ncompounds. The large difference in the formation enthalpies of the oxide and\nsulfide compounds is due to the contribution of local lattice relaxation, which\nis sensitive to the anion size. The solubility of Gd in both EuO and EuS is in\nthe range of 10-20% at room temperature and quickly increases at higher\ntemperatures, indicating that highly doped disordered solid solutions can be\nproduced without the precipitation of secondary phases. We also predict that\nrocksalt GdO can be stabilized under appropriate experimental conditions."
    },
    {
        "anchor": "Ultralow Work Function of the Electride Sr$_3$CrN$_3$: Electrides have valence electrons that occupy free space in the crystal\nstructure, making them easier to extract. This feature can be used in catalysis\nfor important reactions that usually requires a high-temperature and\nhigh-pressure environments, such as ammonia synthesis. In this paper, we use\ndensity functional theory to investigate the behaviour of interstitial\nelectrons of the 1-dimensional electride Sr$_3$CrN$_3$. We find that the bulk\nexcess electron density persists on introduction of surface terminations, that\nthe crystal termination perpendicular to the 1D free-electron channel is highly\nstable and we confirm an extremely low work function with hybrid functional\nmethods. Our results indicate that Sr$_3$CrN$_3$ is a potentially important\nnovel catalyst, with accessible, directional and extractable free electron\ndensity.",
        "positive": "Composition and Stacking Dependent Topology in Bilayers from the\n  Graphene Family: We present a compositional and structural investigation of silicene,\ngermanene, and stanene bilayers from first-principles. Due to the staggering of\nthe individual layers, several stacking patterns are possible, most of which\nare not available to the bilayer graphene. This structural variety, in\nconjunction with the presence of the spin-orbit coupling, unveil a diversity of\nthe electronic properties, with the appearance of distinct band features,\nincluding orbital hybridization and band inversion. We show that for particular\ncases, the intrinsic spin Hall response exhibits signatures of non-trivial\nelectronic band topology, making these structures promising candidates to probe\nDirac-like physics."
    },
    {
        "anchor": "Realizing high Near-Room-Temperature Thermoelectric Performance in\n  n-type Ag2Se through Rashba Effect and Entropy Engineering: Although there are enormous numbers of high-temperature thermoelectric\nmaterials present, designing a near-room-temperature especially n-type\nthermoelectric material with high zT is extremely challenging. Generally,\npristine Ag2Se exhibits unusual low thermal conductivity along with high\nelectrical conductivity and Seebeck coefficient, which leads to high\nthermoelectric performance (n-type) at room temperature. Herein, we report a\npseudoternary phase, Ag2Se0.5Te0.25S0.25, which shows improved thermoelectric\nperformance (zT ~ 2.1 at 400 K). Density functional theory reveals that the\nRashba type of spin-dependent band spitting originated because of Te-doping,\nenhancing carrier mobility. Using density functional perturbation theory, we\nhereby realize that the intrinsic carrier mobility is not only controlled by\ncarrier effective mass, neither deformation potential theory, instead it is\nsubstantially limited by longitudinal optical phonon scattering. In fact,\nlocally off-centered S atoms and rising configurational entropy via\nsubstitution of Te and S atoms in Ag2Se significantly reduce the lattice\nthermal conductivity (klat ~ 0.34 at 400 K). In order to accurately obtain\nelectrical as well as thermal transport coefficient, we adopt deformation\npotential theory based on Boltzmann transport formalism. The combined\nconsequence of the Rashba effect coupled with configurational entropy\nsynergistically results in such high thermoelectric performance with the\ndevelopment of new n-type thermoelectric material working at the\nnear-room-temperature regime.",
        "positive": "Degeneracy and size consistency in electronic density functional theory: The electronic structure calculations based upon energy density functionals\nare highly successful and widely used both in solid state physics and quantum\nchemistry. Moreover, the Hohenberg-Kohn theorems and the Kohn-Sham method\nprovide them with a firm basis. However, several basic issues are not solved,\nand hamper the progress to achieve high accuracy. In this paper we focus on the\nconceptual problem of size consistency, basing our analysis on the\nnon-intensive character of the (spin) electronic density in the presence of\ndegeneracy. We also briefly discuss some of the issues concerning fractional\nelectron numbers from the same point of view, analyzing the behavior of the\nexact functionals for the He and the Hooke's atom series when the number of\nelectrons fluctuates between one and two."
    },
    {
        "anchor": "Magnetic Cluster Expansion model for random and ordered magnetic\n  face-centered cubic Fe-Ni-Cr alloys: A Magnetic Cluster Expansion (MCE) model for ternary face-centered cubic\nFe-Ni-Cr alloys has been developed using DFT data spanning binary and ternary\nalloy configurations. Using this MCE model Hamiltonian, we perform Monte Carlo\nsimulations and explore magnetic structures of alloys over the entire range of\nalloy compositions, considering both random and ordered alloy structures. In\nrandom alloys, the removal of magnetic collinearity constraint reduces the\ntotal magnetic moment but does not affect the predicted range of compositions\nwhere the alloys adopt low temperature ferromagnetic configurations. During\nalloying of ordered fcc Fe-Ni compounds with Cr, chromium atoms tend to replace\nnickel rather than iron atoms. Replacement of Ni by Cr in alloys with high iron\ncontent increases the Curie temperature of the alloys. This can be explained by\nstrong antiferromagnetic Fe-Cr coupling, similar to that found in bcc Fe-Cr\nsolutions, where the Curie temperature increase, predicted by simulations as a\nfunction of Cr concentration, is confirmed by experimental observations.",
        "positive": "Questaal: a package of electronic structure methods based on the linear\n  muffin-tin orbital technique: This paper summarises the theory and functionality behind Questaal, an\nopen-source suite of codes for calculating the electronic structure and related\nproperties of materials from first principles. The formalism of the linearised\nmuffin-tin orbital (LMTO) method is revisited in detail and developed further\nby the introduction of short-ranged tight-binding basis functions for\nfull-potential calculations. The LMTO method is presented in both Green's\nfunction and wave function formulations for bulk and layered systems. The\nsuite's full-potential LMTO code uses a sophisticated basis and augmentation\nmethod that allows an efficient and precise solution to the band problem at\ndifferent levels of theory, most importantly density functional theory, LDA+U,\nquasi-particle self-consistent GW and combinations of these with dynamical mean\nfield theory. This paper details the technical and theoretical bases of these\nmethods, their implementation in Questaal, and provides an overview of the\ncode's design and capabilities."
    },
    {
        "anchor": "Electronic transmission in Graphene suppressed by interlayer\n  interference: We investigate electronic transport property of a graphene monolayer covered\nby a graphene nanoribbon. We demonstrate that electronic transmission of a\nmonolayer can be reduced when covered by a nanoribbon. The transmission\nreduction occurs at different energies determined by the width of nanoribbon.\nWe explain the transmission reduction by using interference between\nwavefunctions in the monolayer and the nanoribbon. Furthermore, we show the\ntransmission reduction of a monolayer is combinable when covered by more than\none nanoribbon and propose a concept of \"combination of control\" for\nnano-application design.",
        "positive": "Magnetic properties of single nanomagnets: EMCD on FePt nanoparticles: Energy-loss magnetic chiral dichroism (EMCD) allows for the quantification of\nmagnetic properties of materials at the nanometer scale. It is shown that with\nthe support of simulations that help to identify the optimal conditions for a\nsuccessful experiment and upon implementing measurement routines that\neffectively reduce the noise floor, EMCD measurements can be pushed towards\nquantitative magnetic measurements even on individual nanoparticles. With this\napproach, the ratio of orbital to spin magnetic moments for the Fe atoms in a\nsingle L$1_0$ ordered FePt nanoparticle is determined to be ${m_l}/{m_s} = 0.08\n\\pm 0.02$. This finding is in good quantitative agreement with the results of\nXMCD ensemble measurements."
    },
    {
        "anchor": "Pressure-induced Lifshitz transition in NbP: Raman, x-ray diffraction,\n  electrical transport and density functional theory: We report high pressure Raman, synchrotron x-ray diffraction and electrical\ntransport studies on Weyl semimetals NbP and TaP along with first-principles\ndensity functional theoretical (DFT) analysis. The frequencies of first-order\nRaman modes of NbP harden with increasing pressure and exhibit a slope change\nat P$_c$ $\\sim$ 9 GPa, and its resistivity exhibits a minimum at P$_c$. The\npressure-dependent volume of NbP exhibits a change in its bulk modulus from 207\nGPa to 243 GPa at P$_c$. Using DFT calculations, we show that these anomalies\nare associated with pressure induced Lifshitz transition which involves\nappearance of electron and hole pockets in its electronic structure. In\ncontrast, results of Raman and synchrotron x-ray diffraction experiments on TaP\nand DFT calculations show that TaP is quite robust under pressure and does not\nundergo any phase transition.",
        "positive": "Universal conductivity and the electrodynamics of graphite at high\n  pressures: We address the in-plane pressure-dependent electrodynamics of graphite\nthrough synchrotron based infrared spectroscopy and ab initio Density\nFunctional Theory calculations. The Drude term remarkably increases upon\npressure application, as a consequence of an enhancement of both electron and\nhole charge densities. This is due to the growth of the band dispersion along\nthe k_z direction between the K and H points of the Brillouin zone. On the\nother hand, the mid-infrared optical conductivity between 800 and 5000 cm-1 is\nalmost flat, and very weakly pressure dependent, at least up to 7 GPa. This\ndemonstrates a surprising robustness of the graphene-like universal quantum\nconductance of graphite, even when the interlayer distance is significantly\nreduced."
    },
    {
        "anchor": "Reliable magnetic domain wall propagation in cross structures for\n  advanced multi-turn sensor devices: We develop and analyze an advanced concept for domain wall based sensing of\nrotations. Moving domain walls in n closed loops with n-1 intersecting\nconvolutions by rotating fields, we can sense n rotations. By combining loops\nwith coprime numbers of rotations, we create a sensor system allowing for the\ntotal counting of millions of turns of a rotating applied magnetic field. We\nanalyze the operation of the sensor and identify the intersecting cross\nstructures as the critical component for reliable operation. In particular\ndepending on the orientation of the applied field angle with the magnetization\nin the branches of the cross, a domain wall is found to propagate in an\nunwanted direction yielding failures and counting errors in the device. To\novercome this limiting factor, we introduce a specially designed syphon\nstructure to achieve the controlled pinning of the domain wall before the cross\nand depinning and propagation only for a selected range of applied field\nangles. By adjusting the syphon and the cross geometry, we find that the\noptimized combination of both structures prevents failures in the full sensor\nstructure yielding robust operation. Our modeling results show that the\noptimized element geometry allows for the realization of the sensor with\ncross-shaped intersections and operation that is tolerant to inaccuracies of\nthe fabrication.",
        "positive": "Large anomalous Nernst and spin Nernst effects in noncollinear\n  antiferromagnets Mn$_3X$ ($X$ = Sn, Ge, Ga): Noncollinear antiferromagnets have recently been attracting considerable\ninterest partly due to recent surprising discoveries of the anomalous Hall\neffect (AHE) in them and partly because they have promising applications in\nantiferromagnetic spintronics. Here we study the anomalous Nernst effect (ANE),\na phenomenon having the same origin as the AHE, and also the spin Nernst effect\n(SNE) as well as AHE and the spin Hall effect (SHE) in noncollinear\nantiferromagnetic Mn$_3X$ ($X$ = Sn, Ge, Ga) within the Berry phase formalism\nbased on {\\it ab initio} relativistic band structure calculations. For\ncomparison, we also calculate the anomalous Nernst conductivity (ANC) and\nanomalous Hall conductivity (AHC) of ferromagnetic iron as well as the spin\nNernst conductivity (SNC) of platinum metal. Remarkably, the calculated ANC at\nroom temperature (300 K) for all three alloys is huge, being up to 5 times\nlarger than that of iron. Moreover, the calculated SNC for Mn$_3$Sn and\nMn$_3$Ga is also large, being as large as that of platinum. This suggests that\nthese anitferromagnets would be useful materials for thermoelectronic devices\nand spin caloritronic devices. The calculated ANC of Mn$_3$Sn and iron are in\nreasonably good agreement with the very recent experiments. The calculated SNC\nof platinum also agrees with the very recent experiments in both sign and\nmagnitude. The calculated thermoelectric and thermomagnetic properties are\nanalyzed in terms of the band structures as well as the energy-dependent AHC,\nANC, SNC and spin Hall conductivity via the Mott relations."
    },
    {
        "anchor": "Highly luminescent silver-based MOFs: Scalable eco-friendly synthesis\n  paving the way for photonics sensors and electroluminescent devices: Luminescent multifunctional nanomaterials are important because of their\npotential impact on the development of key technologies such as smart\nluminescent sensors and solid-state lightings. To be technologically viable,\nthe luminescent material needs to fulfil a number of requirements such as\nfacile and cost-effective fabrication, a high quantum yield, structural\nrobustness, and long-term material stability. To achieve these requirements, an\neco-friendly and scalable synthesis of a highly photoluminescent, multistimuli\nresponsive and electroluminescent silver-based metal-organic framework\n(Ag-MOF), termed \"OX-2\" was developed. Its exceptional photophysical and\nmechanically resilient properties that can be reversibly switched by\ntemperature and pressure make this material stood out over other competing\nluminescent materials. The potential use of OX-2 MOF as a good\nelectroluminescent material was tested by constructing a proof-of-concept\nMOF-LED (light emitting diode) device, further contributing to the rare\nexamples of electroluminescent MOFs. The results reveal the huge potential for\nexploiting the Ag MOF as a multitasking platform to engineer innovative\nphotonic technologies.",
        "positive": "Role of hidden spin polarization in non-reciprocal transport of\n  antiferromagnets: The discovery of hidden spin polarization (HSP) in centrosymmetric\nnonmagnetic crystals, i.e., spatially distributed spin polarization originated\nfrom local symmetry breaking, has promised an expanded material pool for future\nspintronics. However, the measurements of such exotic effects have been limited\nto subtle space- and momentum-resolved techniques, unfortunately hindering\ntheir applications. Here, we theoretically predict macroscopic non-reciprocal\ntransports induced by HSP when coupling another spatially distributed quantity,\nsuch as staggered local moments in a PT-symmetric anti-ferromagnet. By using a\nfour-band model Hamiltonian, we demonstrate that HSP plays a crucial role in\ndetermining the asymmetric bands with respect to opposite momenta. Such band\nasymmetry leads to non-reciprocal nonlinear conductivity, exemplified by\ntetragonal CuMnAs via first-principles calculations. We further provide the\nmaterial design principles for large nonlinear conductivity, including\ntwo-dimensional nature, multiple band crossings near the Fermi level, and\nsymmetry protected HSP. Our work not only reveals direct spintronic\napplications of HSP (such as N\\'eel order detection), but also sheds light on\nfinding observables of other ''hidden effects'', such as hidden optical\npolarization and hidden Berry curvature."
    },
    {
        "anchor": "Real Space Imaging of the Microscopic Origins of the Ultrahigh\n  Dielectric Constant in Polycrystalline CaCu3Ti4O12: The origins of an ultrahigh dielectric constant in polycrystalline\nCaCu3Ti4O12 (CCTO) was studied using the combination of impedance spectroscopy,\nelectron microscopy, and scanning probe microscopy (SPM). Impedance spectra\nindicate that the transport properties in the 0.1 Hz .. 1 MHz frequency range\nare dominated by a single parallel resistive-capacitive (RC) element with a\ncharacteristic relaxation frequency of 16 Hz. Dc potential distributions\nmeasurements by SPM illustrate that significant potential drops occur at the\ngrain boundaries, which thus can be unambiguously identified as the dominant RC\nelement. High frequency ac amplitude and phase distributions illustrate very\nweak contrast at the interfaces, which is indicative of strong capacitive\ncoupling. These results demonstrate that the ultrahigh dielectric constant\nreported for polycrystalline CCTO materials are related to the grain boundary\nbehavior.",
        "positive": "Conductance through atomic point contacts between fcc(100) electrodes of\n  gold: Electrical conductance through various nanocontacts between gold electrodes\nis studied by using the density functional theory, scalar-relativistic\npseudopotentials, generalized gradient approximation for the\nexchange-correlation energy and the recursion-transfer-matrix method along with\nchannel decomposition. The nanocontact is modeled with pyramidal fcc(100) tips\nand 1 to 5 gold atoms between the tips. Upon elongation of the contact by\nadding gold atoms between the tips, the conductance at Fermi energy E_F evolves\nfrom G ~ 3 G_0 to G ~ 1 G_0 (G_0 = 2e/h^2). Formation of a true one-atom point\ncontact, with G ~ 1 G_0 and only one open channel, requires at least one atom\nwith coordination number 2 in the wire. Tips that share a common vertex atom or\ntips with touching vertex atoms have three partially open conductance channels\nat E_F, and the symmetries of the channels are governed by the wave functions\nof the tips. The long 5-atom contact develops conductance oscillations and\nconductance gaps in the studied energy range -3 < E-E_F < 5 eV, which reflects\noscillations in the local density of electron states in the 5-atom linear \"gold\nmolecule\" between the electrodes, and a weak coupling of this \"molecule\" to the\ntips."
    },
    {
        "anchor": "Irreversible transformation of ferromagnetic ordered stripe domains in\n  single-shot IR pump - resonant X-ray scattering probe experiments: The evolution of a magnetic domain structure upon excitation by an intense,\nfemtosecond Infra-Red (IR) laser pulse has been investigated using single-shot\nbased time-resolved resonant X-ray scattering at the X-ray Free Electron laser\nLCLS. A well-ordered stripe domain pattern as present in a thin CoPd alloy film\nhas been used as prototype magnetic domain structure for this study. The\nfluence of the IR laser pump pulse was sufficient to lead to an almost complete\nquenching of the magnetization within the ultrafast demagnetization process\ntaking place within the first few hundreds of femtoseconds following the IR\nlaser pump pulse excitation. On longer time scales this excitation gave rise to\nsubsequent irreversible transformations of the magnetic domain structure. Under\nour specific experimental conditions, it took about 2 nanoseconds before the\nmagnetization started to recover. After about 5 nanoseconds the previously\nordered stripe domain structure had evolved into a disordered labyrinth domain\nstructure. Surprisingly, we observe after about 7 nanoseconds the occurrence of\na partially ordered stripe domain structure reoriented into a novel direction.\nIt is this domain structure in which the sample's magnetization stabilizes as\nrevealed by scattering patterns recorded long after the initial pump-probe\ncycle. Using micro-magnetic simulations we can explain this observation based\non changes of the magnetic anisotropy going along with heat dissipation in the\nfilm.",
        "positive": "Thermodynamic considerations on a class of dislocation-based\n  constitutive models: Dislocations are the main carriers of plastic deformation in crystalline\nmaterials. Physically based constitutive equations of crystal plasticity\ntypically incorporate dislocation mechanisms, using a dislocation density based\ndescription of dislocation microstructure evolution and plastic flow.\nTypically, such constitutive models are not formulated in a thermodynamic\nframework. Nevertheless, fundamental considerations of thermodynamic\nconsistency impose constraints on the admissible range of model parameters\nand/or on the range of application of such models. In particular, it is\nmandatory to ensure that the internal energy increase associated with\ndislocation accumulation is properly accounted for in the local energy balance.\nWe demonstrate on some examples taken from the literature how failure to do so\ncan lead to constitutive equations that violate the first and second laws of\nthermodynamics either generally or in some particular limit cases, and we\ndiscuss how to formulate constraints that recover thermodynamic consistency."
    },
    {
        "anchor": "Approaching Three-Dimensional Quantum Hall effect in Bulk HfTe5: The discovery of quantum Hall effect in two-dimensional (2D) electronic\nsystems inspired the topological classifications of electronic systems1,2. By\nstacking 2D quantum Hall effects with interlayer coupling much weaker than the\nLandau level spacing, quasi-2D quantum Hall effects have been experimentally\nobserved3~7, due to the similar physical origin of the 2D counterpart.\nRecently, in a real 3D electronic gas system where the interlayer coupling is\nmuch stronger than the Landau level spacing, 3D quantum Hall effect has been\nobserved in ZrTe58. In this Letter, we report the electronic transport features\nof its sister bulk material, i.e., HfTe5, under external magnetic field. We\nobserve a series of plateaus in Hall resistance \\r{ho}xy as magnetic field\nincreases until it reaches the quantum limit at 1~2 Tesla. At the plateau\nregions, the longitudinal resistance \\r{ho}xx exhibits local minima. Although\n\\r{ho}xx is still nonzero, its value becomes much smaller than \\r{ho}xy at the\nlast few plateaus. By mapping the Fermi surface via measuring the Shubonikov-de\nHaas oscillation, we find that the strength of Hall plateau is proportional to\nthe Fermi wavelength, suggesting that its formation may be attributed to the\ngap opening from the interaction driven Fermi surface instability. By comparing\nthe bulk band structures of ZrTe5 and HfTe5, we find that there exists an extra\npocket near the Fermi level of HfTe5, which may lead to the finite but nonzero\nlongitudinal conductance.",
        "positive": "An ab initio based approach to optical properties of semiconductor\n  heterostructures: A procedure is presented that combines density functional theory computations\nof bulk semiconductor alloys with the semiconductor Bloch equations, in order\nto achieve an ab initio based prediction of the optical properties of\nsemiconductor alloy heterostructures. The parameters of an eight-band\nkp-Hamiltonian are fitted to the effective band structure of an appropriate\nalloy. The envelope function approach is applied to model the quantum well\nusing the kp-wave functions and eigenvalues as starting point for calculating\nthe optical properties of the heterostructure. It is shown that Luttinger\nparameters derived from band structures computed with the TB09 density\nfunctional reproduce extrapolated values. The procedure is illustrated by\ncomputing the absorption spectra for a (AlGa)As/Ga(AsP)/(AlGa)As quantum well\nsystem with varying phosphide content in the active layer."
    },
    {
        "anchor": "The ferroelectric-paraelectric phase transition in BiFeO3: crystal\n  structure of the orthorhombic beta-phase: A detailed investigation using variable temperature powder neutron\ndiffraction demonstrates that BiFeO3 undergoes a phase transition from the\nferroelectric alpha phase (rhombohedral, R3c) to a paraelectric beta phase\n(orthorhombic, Pbnm) between 820 oC and 830 oC. Co-existence of both phases\nover a finite temperature interval, together with abrupt changes in key\nstructural parameters, confirm that the transition is firstorder. The beta\nphase corresponds to the GdFeO3-type perovskite. The metastability of BiFeO3\nrelative to Bi2Fe4O9 above 810 oC precludes observation of a reported cubic\ngamma phase above 925 oC under the present experimental conditions.",
        "positive": "The Effect of Structural Distortions on the Electronic Structure of\n  Carbon Nanotubes: We calculated the effects of structural distortions on the electronic\nstructure of carbon nanotubes. The key modification of the electronic structure\nbrought about by bending a nanotube involves an increased mixing of $\\sigma$\nand $\\pi$-states. This mixing leads to an enhanced density-of-states in the\nvalence band near the Fermi energy region. While in a straight tube the states\naccessible for electrical conduction are essentially pure C($2p_{\\pi}$)-states,\nthey acquire significant C($2sp_{\\sigma}$) character upon bending. Bending also\nleads to a charge polarization of the C-C bonds in the deformed region\nreminiscent of interface dipole formation. Scattering of conduction electrons\nat the distorted regions may lead to electron localization at low temperatures."
    },
    {
        "anchor": "Distinguishing antiferromagnetic spin sublattices via the spin Seebeck\n  effect: Antiferromagnets are beneficial for future spintronic applications due to\ntheir zero magnetic moment and ultrafast dynamics. But gaining direct access to\ntheir antiferromagnetic order and identifying the properties of individual\nmagnetic sublattices, especially in thin films and small-scale devices, remains\na formidable challenge. So far, the existing read-out techniques such as\nanisotropic magnetoresistance, tunneling anisotropic magnetoresistance, and\nspin-Hall magnetoresistance, are even functions of sublattice magnetization and\nthus allow us to detect different orientations of the N\\'eel order for\nantiferromagnets with multiple easy axes. In contrast direct electrical\ndetection of oppositely oriented spin states along the same easy axes (e.g., in\nuniaxial antiferromagnets) requires sensitivity to the direction of individual\nsublattices and thus is more difficult. In this study, using spin Seebeck\neffect, we report the electrical detection of the two sublattices in a uniaxial\nantiferromagnet Cr2O3. We find the rotational symmetry and hysteresis behavior\nof the spin Seebeck signals measured at the top and bottom surface reflect the\ndierction of the surface sublattice moments, but not the N\\'eel order or the\nnet moment in the bulk. Our results demonstrate the important role of interface\nspin sublattices in generating the spin Seebeck voltages, which provide a way\nto access each sublattice independently, enables us to track the full rotation\nof the magnetic sublattice, and distinguish different and antiparallel\nantiferromagnetic states in uniaxial antiferromagnets.",
        "positive": "Cubic BN optical gap and intragap optically active defects: We report a comprehensive study on the optical properties of cubic boron\nnitride (c-BN) and its optically active defects. Using electron energy-loss\nspectroscopy (EELS) within a monochromated scanning transmission electron\nmicroscope (STEM) on the highest-quality crystals available, we demonstrate\nunequivocally that the optical-gap energy of c-BN slightly exceeds 10 eV.\nFurther theoretical analysis in the framework of the Bethe-Salpeter equation of\nmany-body perturbation theory supports this result. The spatial localization of\ndefect-related emissions has been investigated using nanometric resolved\ncathodoluminescence (nano-CL) in a STEM. By high-temperature annealing a c-BN\npowder, we have promoted phase transitions in nanometric domains which have\nbeen detected by the appearance of specific hexagonal-phase signatures in both\nEELS and CL spectra. A high number of intragap optically active centers are\nknown in c-BN, but the literature is rather scattered and hence has been\nsummarized here. For several emission lines we have obtained nano-CL maps which\nshow emission spot sizes as small as few tens of nanometers. Finally, by\ncoupling nano-CL to a Hanbury-Brown-Twiss intensity interferometer, we have\naddressed individual spots in order to identify the possible presence of\nsingle-photon sources. The observed CL bunching effect is compatible with a\nlimited set of single-photon emitters and it permits obtaining emission\nlifetimes of the order of the nanosecond."
    },
    {
        "anchor": "Fabrication of multilayer edge molecular electronics and spintronics\n  devices: Advancement of molecular devices will critically depend on the approach to\nestablish electrical connections to the functional molecule(s). We produced a\nmolecular device strategy which is based on chemically attaching of molecules\nbetween the two magnetic/nonmagnetic metallic electrodes along the multilayer\nedge(s) of a prefabricated tunnel junction. Here, we present the fabrication\nmethodology for producing these multilayer edge molecular\nelectronics/spintronics devices (MEMEDs/MEMSDs) and details of the associated\nchallenges and their solutions. The key highlight of our MEMED/MEMSD approach\nis the method of producing exposed side edge(s) of a tunnel junction for\nhosting molecular conduction channels by a simple liftoff method. The liftoff\nmethod ensured that along the tunnel junction edges, the minimum gap between\nthe two metal electrodes equaled the thickness of the tunnel barrier. All of\nthe tunnel junction test beds used a ~2 nm alumina (AlOx) tunnel barrier. We\nsuccessfully bridged the magnetic organometallic molecular clusters and\nnon-magnetic alkane molecules across the AlOx insulator along the exposed\nedges, to transform the prefabricated tunnel junction into the molecular\nelectronics or spintronics devices. Tunnel junction test beds were fabricated\nwith a variety of metal electrodes, such as NiFe, Co, Ni, Au, Ta, Cu and Si.\nStability of ultrathin thin AlOx varied with the type of bottom metal\nelectrodes used for making MEMED/MEMSD. Additionally, molecular solution used\nfor bridging molecular channels in a MEMED was not compatible with all the\nmetal electrodes; molecular solution resistant ferromagnetic electrodes were\ndeveloped for the fabrication of MEMSDs. MEMSD approach offers an open platform\nto test virtually any combination of magnetic electrodes and magnetic\nmolecules, including single molecular magnets.",
        "positive": "Effects of paramagnetic fluctuations on the thermochemistry of MnO (100)\n  surfaces in the oxygen evolution reaction: We investigated the effects of paramagnetic (PM) fluctuations on the\nthermochemistry of the MnO(100) surface in the oxygen evolution reaction (OER)\nusing the \"noncollinear magnetic sampling method \\textit{plus} $U$\"\n(NCMSM$+U$). Various physical properties, such as the electronic structure,\nfree energy, and charge occupation, of the MnO (100) surface in the PM state\nwith several OER intermediates, were reckoned and compared to those in the\nantiferromagnetic (AFM) state. We found that PM fluctuation enhances charge\ntransfer from a surface Mn ion to each of the intermediates and strengthens the\nchemical bond between them, while not altering the overall features, such as\nthe rate determining step and resting state, in reaction pathways. The enhanced\ncharge transfer can be attributed to the delocalized nature of valence bands\nobserved in the PM surface. In addition, it was observed that chemical-bond\nenhancement depends on the intermediates, resulting in significant deviations\nin reaction energy barriers. Our study suggests that PM fluctuations play a\nsignificant role in the thermochemistry of chemical reactions occurring on\ncorrelated oxide surfaces."
    },
    {
        "anchor": "Nonlinear pressure dependence of T_N in almost multiferroic EuTiO_3: The antiferromagnetic (AFM) phase transition temperature T_N of EuTiO_3 has\nbeen studied as a function of pressure p. The data reveal a nonlinear\ndependence of T_N on p with T_N increasing with increasing pressure. The\nexchange interactions exhibit an analogous dependence on p as T_N (if the\nabsolute value of the nearest neighbor interaction is considered) and there is\nevidence that the AFM transition is robust with increasing pressure. The\ncorresponding Weiss temperature {\\Theta}_W remains anomalous since it always\nexhibits positive values. The data are analyzed within the Bloch power law\nmodel and provide excellent agreement with experiment.",
        "positive": "On the origin of electron accumulation layer at clean InAs(111) surfaces: In this paper, we provide a comprehensive theoretical analysis of the\nelectronic structure of InAs(111) surfaces with a special attention paid to the\nenergy region close to the fundamental bandgap. Starting from the bulk\nelectronic structure of InAs as calculated using PBE functional with included\nHubbard correction and spin-orbit coupling, we deliver proper values for the\nbandgap, split-off energy, as well as effective electron, light- and heavy-hole\nmasses in full consistency with available experimental results. On the basis of\noptimized atomic surfaces we recover scanning tunneling microscopy images,\nwhich being supplied with accessible experimental data make it possible to\nspeculate on the formation of electron accumulation layer for both As- and\nIn-terminated InAs(111) surfaces. Moreover, these results are accompanied by\nband structure simulations of conduction band states."
    },
    {
        "anchor": "Theory of the spin relaxation of conduction electrons in silicon: A realistic pseudopotential model is introduced to investigate the\nphonon-induced spin relaxation of conduction electrons in bulk silicon. We find\na surprisingly subtle interference of the Elliott and Yafet processes affecting\nthe spin relaxation over a wide temperature range, suppressing the significance\nof the intravalley spin-flip scattering, previously considered dominant, above\nroughly 120 K. The calculated spin relaxation times $T_1$ agree with the spin\nresonance and spin injection data, following a $T^{-3}$ temperature dependence.\nThe valley anisotropy of $T_1$ and the spin relaxation rates for hot electrons\nare predicted.",
        "positive": "Isotopic study of Raman active phonon modes in $\u03b2$-Ga$_{2}$O$_{3}$: Holding promising applications in power electronics, the wide band gap\nmaterial gallium oxide has emerged as a vital alternative to materials like GaN\nand SiC. The detailed study of phonon modes in $\\beta$-Ga$_{2}$O$_{3}$ provides\ninsights into fundamental material properties such as crystal structure and\norientation and can contribute to the identification of dopants and point\ndefects. We investigate the Raman active phonon modes of\n$\\beta$-Ga$_{2}$O$_{3}$ in two different oxygen isotope compositions\n($^{16}$O,$^{18}$O) by experiment and theory: By carrying out polarized\nmicro-Raman spectroscopy measurements on the (010) and ($\\bar{2}$01) planes, we\ndetermine the frequencies of all 15 Raman active phonons for both\nisotopologues. The measured frequencies are compared with the results of\ndensity functional perturbation theory (DFPT) calculations. In both cases, we\nobserve a shift of Raman frequencies towards lower energies upon substitution\nof $^{16}$O with $^{18}$O. By quantifying the relative frequency shifts of the\nindividual Raman modes, we identify the atomistic origin of all modes (Ga-Ga,\nGa-O or O-O) and present the first experimental confirmation of the\ntheoretically calculated energy contributions of O lattice sites to Raman\nmodes. We find that oxygen substitution on the O$_{\\mathrm{II}}$ site leads to\nan elevated relative frequency shift compared to O$_{\\mathrm{I}}$ and\nO$_{\\mathrm{III}}$ sites. This study presents a blueprint for the future\nidentification of different point defects in Ga$_{2}$O$_{3}$ by Raman\nspectroscopy."
    },
    {
        "anchor": "Anomalous magnetic anisotropy of the topmost surface layer of Ni(110): The orientation of the magnetization of a Ni(110) surface was investigated\nusing techniques with different probing depths. By making use of electron\ncapture into excited states of fast He atoms, we found that the magnetization\nof the topmost surface layer is not aligned along the easy axes of Ni. However,\nfor a 50 ML film Fe on Ni(110) we observed the magnetization of the topmost Fe\nsurface layer is along the easy axes of Fe.",
        "positive": "Where is the residual entropy of a glass hiding?: We revisit the controversy, discussed recently by Goldstein in this\njournal[J. Chem. Phys. 128,154510 (2008)], whether the residual entropy is real\nor fictional. It is shown that the residual entropy loss conjecture (ELC) at\nthe glass transition, which results in a discontinuous entropy violates many\nfundamental principles of classical thermodynamics, and also contradicts some\nexperimental facts. Assuming, as is common in the field, that glasses are in\ninternal equilibrium, we show that the continuity of enthalpy and volume at the\nglass transition require the continuity of the Gibbs free energy and the\nentropy, which contradicts ELC. It is then argued that ELC is founded on an\nincorrect understanding of what it means for a glass to be kinetically trapped\nin a basin and of the concept of probability and entropy. Once this\nmisunderstanding is corrected in our approach by the proper identification of\nentropy as the ensemble entropy, which is in accordance with the principle of\nreproducibility (see Sect. II), it follows immediately that the residual\nentropy does not disappear in a kinetically frozen glassy state and all the\nviolations of thermodynamics disappear. We show that the temporal definition of\nentropy over finite times does not make sense for glasses as it is not unique.\nThere is no loss of ergodicity and causality, contrary to some recent claims."
    },
    {
        "anchor": "Ab initio study of electron-phonon interaction in phosphorene: The monolayer of black phosphorous, or phosphorene, has recently emerged as a\nnew 2D semiconductor with intriguing highly anisotropic transport properties.\nExisting calculations of its intrinsic phonon-limited electronic transport\nproperties so far rely on the deformation potential approximation, which is in\ngeneral not directly applicable to anisotropic materials since the deformation\nalong one specific direction can scatter electrons traveling in all directions.\nWe perform a first-principles calculation of the electron-phonon interaction in\nphosphorene based on density functional perturbation theory and Wannier\ninterpolation. Our calculation reveals that 1) the high anisotropy provides\nextra phase space for electron-phonon scattering, and 2) optical phonons have\nappreciable contributions. Both effects cannot be captured by the deformation\npotential calculations.",
        "positive": "Highly Boron-Doped Graphite and Diamond Synthesized From Adamantane and\n  Ortho-Carborane under High Pressure: This work demonstrates the effectiveness of the high-pressure method for the\nproduction of graphite and diamond with a high degree of boron doping using\nadamantanecarborane mixture as a precursor. At 8 GPa and $1700 ^{o}C$, graphite\nis obtained from adamantane $C_{10}H_{16}$, whereas microcrystals of\nboron-doped diamond (2{\\div}2.5 at.% of boron) are synthesized from a mixture\nof adamantane and ortho-carborane $C_{2}B_{10}H_{12}$ (atomic ratio B:C =\n5:95). This result shows convincingly the catalytical activity of boron in the\nsynthesis of diamond under high pressure. At pressures lower than 7 GPa, only\ngraphite is synthesized from the adamantane and carborane mixture.\nGraphitization starts at quite low temperatures (below $1400 ^{o}C$) and an\nincrease in temperature simultaneously increases boron content and the quality\nof the graphite crystal lattice. Thorough study of the material structure\nallows us to assume that the substitutional boron atoms are distributed\nperiodically and equidistantly from each other in the graphite layers at high\nboron concentrations (>1 at.%). The theoretical arguments and model ab initio\ncalculations confirm this assumption and explain the experimentally observed\nboron concentrations."
    },
    {
        "anchor": "Fermi Level Tuning of Epitaxial Sb2Te3 Thin Films on Graphene by\n  Regulating Intrinsic Defects and Substrate Transfer Doping: High-quality Sb2Te3 films are obtained by molecular beam epitaxy on graphene\nsubstrate and investigated by in situ scanning tunneling\nmicroscopy/spectroscopy. Intrinsic defects responsible for the natural p-type\nconductivity of Sb2Te3 are identified to be the Sb vacancies and SbTe antisites\nin agreement with first-principles calculations. By minimizing defect\ndensities, coupled with a transfer doping by the graphene substrate, the Fermi\nlevel of Sb2Te3 thin films can be tuned over the entire range of the bulk band\ngap. This establishes the necessary condition to explore topological insulator\nbehaviors near the Dirac point.",
        "positive": "Metamaterials proposed as perfect magnetoelectrics: Magnetoelectric susceptibility of a metamaterial built from split ring\nresonators have been investigated both experimentally and within an equivalent\ncircuit model. The absolute values have been shown to exceed by two orders of\nmagnitude that of classical magnetoelectric materials. The metamaterial\ninvestigated reaches the theoretically predicted value of the magnetoelectric\nsusceptibility which is equal to the geometric average of the electric and\nmagnetic susceptibilities."
    },
    {
        "anchor": "Robust non-adiabatic molecular dynamics for metals and insulators: We present a new formulation of the correlated electron-ion dynamics (CEID)\nscheme, which systematically improves Ehrenfest dynamics by including quantum\nfluctuations around the mean-field atomic trajectories. We show that the method\ncan simulate models of non-adiabatic electronic transitions, and test it\nagainst exact integration of the time-dependent Schroedinger equation. Unlike\nprevious formulations of CEID, the accuracy of this scheme depends on a single\ntunable parameter which sets the level of atomic fluctuations included. The\nconvergence to the exact dynamics by increasing the tunable parameter is\ndemonstrated for a model two level system. This algorithm provides a smooth\ndescription of the non-adiabatic electronic transitions which satisfies the\nkinematic constraints (energy and momentum conservation) and preserves quantum\ncoherence. The applicability of this algorithm to more complex atomic systems\nis discussed.",
        "positive": "Multi-Meron Interactions and Statistics in Two-Dimensional Materials: As a fundamental type of topological spin textures in two-dimensional (2D)\nmagnets, a magnetic meron carries half-integer topological charge and forms a\npair with its antithesis to keep the stability in materials. However, it is\nchallenging to quantitatively calculate merons and their dynamics by using the\nwidely used continuum model because of the characteristic highly inhomogeneous\nspin textures. In this work, we develop a discrete method to address the\nconcentrated spin structures around the core of merons. We reveal a\nlogarithmic-scale interaction between merons when their distance is larger than\ntwice their core size and obtain subsequent statistics of meron gas. The model\nalso predicts how these properties of single and paired merons evolve with\nmagnetic exchange interactions, and the results are in excellent agreement with\nthe Monte Carlo simulations using the parameters of real 2D van der Waals\nmagnetic materials. This discrete approach not only shows equilibrium static\nstatistics of meron systems but also is useful to further explore the dynamic\nproperties of merons through the quantified pairing interactions."
    },
    {
        "anchor": "Quantitatively Predicting Modal Thermal Conductivity of Nanocrystalline\n  Si by full band Monte Carlo simulations: Thermal transport of nanocrystalline Si is of great importance for the\napplication of thermoelectrics. A better understanding of the modal thermal\nconductivity of nanocrystalline Si will be expected to benefit the efficiency\nof thermoelectrics. In this work, the variance reduced Monte Carlo simulation\nwith full band of phonon dispersion is applied to study the modal thermal\nconductivity of nanocrystalline Si. Importantly, the phonon modal transmissions\nacross the grain boundaries which are modeled by the amorphous Si interface are\ncalculated by the mode-resolved atomistic Greens function method. The predicted\nratios of thermal conductivity of nanocrystalline Si to that of bulk Si agree\nwell with that of the experimental measurements in a wide range of grain size.\nThe thermal conductivity of nanocrystalline Si is decreased from 54 percent to\n3 percent and the contribution of phonons with mean free path larger than the\ngrain size increases from 30 percent to 96 percnet as the grain size decreases\nfrom 550 nm to 10 nm. This work demonstrates that the full band Monte Carlo\nsimulation using phonon modal transmission by the mode-resolved atomistic\nGreens function method can capture the phonon transport picture in complex\nnanostructures, and therefore can provide guidance for designing high\nperformance Si based thermoelectrics.",
        "positive": "Efficient spin transport in a paramagnetic insulator: The discovery of new materials that efficiently transmit spin currents has\nbeen important for spintronics and material science. The electric insulator\n$\\mathrm{Gd}_3\\mathrm{Ga}_5\\mathrm{O}_{12}$ (GGG) is a superior substrate for\ngrowing magnetic films, but has never been considered as a conduit for spin\ncurrents. Here we report spin current propagation in paramagnetic GGG over\nseveral microns. Surprisingly, the spin transport persists up to temperatures\nof 100 K $\\gg$ $T_{\\mathrm{g}} = 180$ mK, GGG's magnetic glass-like transition\ntemperature. At 5 K we find a spin diffusion length ${\\lambda_{\\mathrm{GGG}}} =\n1.8 \\pm 0.2 {\\mu}$m and a spin conductivity ${\\sigma}_{\\mathrm{GGG}} = (7.3 \\pm\n0.3) \\times10^4$ $\\mathrm{Sm}^{-1}$ that is larger than that of the record\nquality magnet $\\mathrm{Y}_3\\mathrm{Fe}_5\\mathrm{O}_{12}$ (YIG). We conclude\nthat exchange coupling is not required for efficient spin transport, which\nchallenges conventional models and provides new material-design strategies for\nspintronic devices."
    },
    {
        "anchor": "Band renormalization of a polymer physisorbed on graphene investigated\n  by many-body perturbation theory: Many-body perturbation theory at the $G_0W_0$ level is employed to study the\nelectronic properties of poly(\\emph{para}-phenylene) (PPP) on graphene.\nAnalysis of the charge density and the electrostatic potential shows that the\npolymer-surface interaction gives rise to the formation of only weak surface\ndipoles with no charge transfer between the polymer and the surface. In the\nlocal-density approximation (LDA) of density-functional theory, the band\nstructure of the combined system appears as a superposition of the eigenstates\nof its constituents. Consequently, the LDA band gap of PPP remains unchanged\nupon adsorption onto graphene. $G_0W_0$ calculations, however, renormalize the\nelectronic levels of the weakly physisorbed polymer. Thereby, its band gap is\nconsiderably reduced compared to that of the isolated PPP chain. This effect\ncan be understood in terms of image charges induced in the graphene layer,\nwhich allows us to explain the quasi-particle gap of PPP versus\npolymer-graphene distance by applying a classical image-potential model. For\ndistances below 4.5 {\\AA}, however, deviations from this simple classical model\narise which we qualitatively explain by taking into account the polarizablity\nof the adsorbate. For a quantitative description with predictive power,\nhowever, we emphasize the need for an accurate ab-initio description of the\nelectronic structure for weakly coupled systems at equilibrium bonding\ndistances.",
        "positive": "Effect of Grain Orientation and Local Strains on Void Growth and\n  Coalescence in Titanium: Ductile fracture has been extensively studied in metals with weak mechanical\nanisotropy such as copper and aluminum. The fracture of more anisotropic\nmetals, especially those with a hexagonal crystal structure (e.g. titanium),\nremains far less understood. This paper investigates the ductile fracture\nprocess in commercially pure titanium (CP-Ti) with particular emphasis on the\ninfluence of grain orientation and local state of strain on void growth. An\nexperimental approach was developed to directly relate the growth of a void in\nthree dimensions to its underlying grain orientation. Grain orientation was\nobtained by electron back scattered diffraction on void-containing CP-Ti sheets\nprior to their diffusion bonding. Changes in void dimensions were measured\nduring in-situ straining within an x-ray tomography system. The strong\ninfluence of the embedded grain orientation and that of its neighbors on void\ngrowth rate and coalescence has been experimentally quantified. Finite element\ncrystal plasticity simulations that take into account both grain orientation\nand the local strain state were found to predict the experimental void growth.\nGrains where basal slip dominates show the largest void growth rates because\nthey are closer to a plane strain condition that favors void growth and\ncoalescence."
    },
    {
        "anchor": "Parallel mode differential phase contrast in transmission electron\n  microscopy, II: K$_2$CuF$_4$ phase transition: In Part I of this diptych, we outlined the theory and an analysis methodology\nfor quantitative phase recovery from real-space distortions of Fresnel images\nacquired in the parallel mode of transmission electron microscopy (TEM). In\nthat work, the properties of the method, termed TEM-differential phase contrast\n(TEM-DPC), were highlighted through the use of simulated data. In this work, we\nexplore the use of the TEM-DPC technique with experimental cryo-TEM images of a\nthin lamella of a low temperature two-dimensional (2-D) ferromagnetic material,\nK$_2$CuF$_4$, to perform two tasks. First, using images recorded below the\nordering temperature, we compare the TEM-DPC method to the transport of\nintensity one for phase recovery, and discuss the relative advantages the\nformer has for experimental data. Second, by tracking the induction of the\nsample as it is driven through a phase transition by heating, we extract\nestimates for the critical temperature and critical exponent of the order\nparameter. The value of the latter is consistent with the 2-D XY class, raising\nthe prospect that a Kosterlitz--Thoules transition may have occurred.",
        "positive": "Accumulation-mode two-dimensional field-effect transistor: Operation\n  mechanism and thickness scaling rule: Understanding the operation mode of a two-dimensional (2D) material-based\nfield-effect transistor (FET) is one of the most essential issues in the study\nof electronics and physics. The existing Schottky barrier-FET model for devices\nwith global back gate and metallic contacts overemphasizes the metal-2D contact\neffect, and the widely observed residual conductance cannot be explained by\nthis model. Here, an accumulation-mode FET model, which directly reveals 2D\nchannel transport properties, is developed based on a partial top-gate MoS2 FET\nwith metallic contacts and a channel thickness of 0.65~118 nm. The operation\nmechanism of an accumulation-mode FET is validated and clarified by carefully\nperformed capacitance measurements. A depletion capacitance-quantum capacitance\ntransition is observed. After the analysis of the MoS2 accumulation-mode FET,\nwe have confirmed that most 2D-FETs show accumulation-mode behavior. The\nuniversal thickness scaling rule of 2D-FETs is then proposed, which provides\nguidance for future research on 2D materials."
    },
    {
        "anchor": "Tip-induced domain protrusion in ferroelectric films with in-plane\n  polarization: Charge manipulation and fabrication of stable domain patterns in\nferroelectric materials by scanning probe microscopy open up broad avenues for\nthe development of tunable electronics. Harnessing the polarization energy and\nelectrostatic forces with specific geometry of the system enables producing the\nnanoscale domains by-design. Along with that, domain engineering requires\nmastery of underlying physical mechanisms that govern the domain formation.\nHere, we present a theoretical description of the domain formation by a\nscanning probe microscopy tip in a ferroelectric film with strong in-plane\nanisotropy of polarization. We demonstrate that local charge injection produces\nwedge-shaped domains that propagate along the anisotropy axis, whereas the\ntip-written lines of charge generate a comb-like domain structure. The results\nof our calculations agree with earlier experimental observations and allow for\nthe optimization of the targeted domain structures.",
        "positive": "Collective effects in the 2D lattices of the magnetic nanoparticles: The work is devoted to investigation of the collective behavior of the\nregular rectangular lattices of the NiFe nanoparticles caused by the\ndipole-dipole interaction between them. The samples was prepared by the method\nof the electron lithography and consist of about 100000 particles of\napproximately 50 nm size. The magnetization curves were investigated by the\nHall magnetometry for the different orientation of the external magnetic field\nat 4.2K and 77K. The results points on the collective behavior of the system.\nThe observed peculiarities we connect with the quasi-one-dimensional behavior\nof the system and the formation of the solitons in the system."
    },
    {
        "anchor": "Mending Cracks in Rutile TiO$_{2}$ with Electron Beam: Restructuring of rutile TiO$_{2}$ under electron beam irradiation driven by\nradiolysis was observed and analyzed using a combination of atomic-resolution\nimaging and electron energy loss spectroscopy (EELS) in scanning transmission\nelectron microscopy (STEM). It was determined that a high-energy (80-300 keV)\nelectron beam at high doses ($\\gtrapprox 10^7 \\ e/nm^2$) can constructively\nrestructure rutile TiO$_{2}$ with an efficiency of $6\\times 10^{-6}$. These\nobservations were realized using rutile TiO$_{2}$ samples with atomically sharp\nnanometer-wide cracks. Based on atomic-resolution STEM imaging and quantitative\nEELS analysis, we propose a $\"$ 2-step $\"$ rolling model of the octahedral\nbuilding blocks of the crystal to account for observed radiolysis-driven atomic\nmigration.",
        "positive": "Zig-zag charged domain walls in ferroelectric PbTiO$_3$: We report a theoretical investigation of a charged 180$^\\circ$ domain wall in\nferroelectric PbTiO$_3$, compensated by randomly distributed immobile charge\ndefects. For this we utilize atomistic shell-model simulations and continuous\nphase-field simulations in the framework of the Ginzburg-Landau-Devonshire\nmodel. We predict that domain walls form a zig-zag pattern and we discuss its\nproperties in a broad interval of compensation-region widths, ranging from a\ncouple to over a hundred nanometers."
    },
    {
        "anchor": "Vanadium substitution: a simple and efficient way to improve UV sensing\n  in ZnO: UV sensing in pure ZnO is due to oxygen adsorption/desorption process from\nZnO surface. Vanadium doping improves UV sensitivity of ZnO. Enhancement in UV\nsensitivity in doped ZnO is attributed to trapping and de-trapping of electrons\nat V4+ & V5+-related defect states. An extra electron in the V4+ state is\nexcited under UV illumination while in absence of the same a trapping happens\nat the V5+ state. An insight to the mechanism is obtained by an analytic study\nof the response phenomenon.",
        "positive": "Au-Ge alloys for wide-range low-temperature on-chip thermometry: We present results of a Au-Ge alloy that is useful as a resistance-based\nthermometer from room temperature down to at least \\SI{0.2}{\\kelvin}. Over a\nwide range, the electrical resistivity of the alloy shows a logarithmic\ntemperature dependence, which simultaneously retains the sensitivity required\nfor practical thermometry while also maintaining a relatively modest and\neasily-measurable value of resistivity. We characterize the sensitivity of the\nalloy as a possible thermometer and show that it compares favorably to\ncommercially-available temperature sensors. We experimentally identify that the\ncharacteristic logarithmic temperature dependence of the alloy stems from\nKondo-like behavior induced by the specific heat treatment it undergoes."
    },
    {
        "anchor": "The atomic lensing model: new opportunities for atom-by-atom metrology\n  of heterogeneous nanomaterials: The atomic lensing model has been proposed as a promising method facilitating\natom-counting in heterogeneous nanocrystals [KHW van den Bos et. al, Phys. Rev.\nLett. 116 (2016) 246101] Here, image simulations will validate the model, which\ndescribes dynamical diffraction as a superposition of individual atoms\nfocussing the incident electrons. It will be demonstrated that the model is\nreliable in the annular dark field regime for crystals having columns\ncontaining dozens of atoms. By using the principles of statistical detection\ntheory, it will be shown that this model gives new opportunities for detecting\ncompositional differences.",
        "positive": "Uncovering Material Deformations via Machine Learning Combined with\n  Four-Dimensional Scanning Transmission Electron Microscopy: Understanding lattice deformations is crucial in determining the properties\nof nanomaterials, which can become more prominent in future applications\nranging from energy harvesting to electronic devices. However, it remains\nchallenging to reveal unexpected deformations that crucially affect material\nproperties across a large sample area. Here, we demonstrate a rapid and\nsemi-automated unsupervised machine learning approach to uncover lattice\ndeformations in materials. Our method utilizes divisive hierarchical clustering\nto automatically unveil multi-scale deformations in the entire sample flake\nfrom the diffraction data using four-dimensional scanning transmission electron\nmicroscopy (4D-STEM). Our approach overcomes the current barriers of large 4D\ndata analysis and enables extraction of essential features even without a\npriori knowledge of the sample. Using this purely data-driven analysis, we have\nuncovered different types of material deformations, such as strain, lattice\ndistortion, bending contour, etc., which can significantly impact the band\nstructure and subsequent performance of nanomaterials-based devices. We\nenvision that this data-driven procedure will provide insight into the\nintrinsic structures and accelerate the discovery of novel materials."
    },
    {
        "anchor": "Energy decomposition analysis of neutral and negatively charged\n  borophenes: The effect of external static charging on borophenes - 2D boron crystals - is\ninvestigated by using first principles calculations. The influence of the\nexcess negative charge on the stability of the 2D structures is examined using\na very simple analysis of decomposition of the binding energy of a given boron\nlayer into contributions coming from boron atoms that have different\ncoordination numbers. This analysis is important to understand how the local\nneighbourhood of an atom influences the overall stability of the monolayer\nstructure. The decomposition is done for the $\\alpha$-sheet and its related\nfamily of structures. From this analysis, we have found a preference for 2D\nboron crystals with very small or very high charges per atom. The structures\nwith intermediate charges are energetically not favourable. We have also found\na clear preference in terms of binding energy for the experimentally seen\n$\\gamma$-sheet and $\\delta$-sheet structures that is almost independent on the\nconsidered excess of negative charge of the structures. On the other hand, we\nhave shown that a model based solely on nearest-neighbour interactions,\nalthough instructive, is too simple to predict binding energies accurately.",
        "positive": "Ferroelectric, quantum paraelectric or paraelectric? Calculating the\n  evolution from BaTiO$_3$ to SrTiO$_3$ to KTaO$_3$ using a single-particle\n  quantum-mechanical description of the ions: We present an inexpensive first-principles approach for describing quantum\nparaelectricity that combines density functional theory (DFT) treatment of the\nelectronic subsystem with quantum mechanical treatment of the ions through\nsolution of the single-particle Schr\\\"odinger equation with the DFT-calculated\npotential. Using BaTiO$_3$, SrTiO$_3$ and KTaO$_3$ as model systems, we show\nthat the approach can straightforwardly distinguish between ferroelectric,\nparaelectric and quantum paraelectric materials, based on simple quantities\nextracted from standard density functional and density functional perturbation\ntheories. We calculate the influence of isotope substitution and strain on the\nquantum paraelectric behavior, and find that, while complete replacement of\noxygen-16 by oxygen-18 has a surprisingly small effect, experimentally\naccessible strains can induce large changes. Finally, we collect the various\nchoices for the phonon mass that have been introduced in the literature. We\nidentify those that are most physically meaningful by comparing with our\nresults that avoid such a choice through the use of mass-weighted coordinates."
    },
    {
        "anchor": "Temperature-induced suppression of structural disproportionation in\n  paramagnetic quantum materials: With the development of electronic structure theory, a new class of materials\n- quantum ones has been recognized by the community. Traditionally, it has been\nbelieved that the properties of such compounds cannot be described within the\nframework of modern density functional theory, and indeed, more advanced\npost-mean-field theory methods are needed. Motivated by this, herein, we\ndevelop a fundamental understanding of such complex materials using the example\nof paramagnetic YNiO3, which is experimentally known to exhibit\nmetal-to-insulator phase transition. We show that this material has a\ntemperature-dependent distribution of local structural and spin motifs. Thus,\nwhile at low temperatures, YNiO3 has distinct structural disproportionation\nwith the formation of large and small octahedra, as the temperature increases,\nthis disproportionation is suppressed. We also explain the paramagnetic\nmonoclinic to paramagnetic orthorhombic phase transition within the double-well\nto single-well energy profile, predicting the variation of the corresponding\nenergy profile as a function of octahedral size distribution. In this way, we\ndemonstrate a fundamental understanding of structural phase transitions in\nquantum materials, giving insight into how it can be used for different\napplications and what minimum level of theory is needed to describe such types\nof complex materials correctly.",
        "positive": "Nature of Valance Band Splitting on Multilayer MoS2: Understanding the origin of splitting of valance band is important since it\ngoverns the unique spin and valley physics in few-layer MoS2. With first\nprinciple methods, we explore the effects of spin-orbit coupling and layer's\ncoupling on few-layer MoS2. It is found that intra-layer spin-orbit coupling\nhas a major contribution to the splitting of valance band at K. In double-layer\nMoS2, the layer's coupling results in the widening of energy gap of splitted\nstates induced by intra-layer spin-orbit coupling. The valance band splitting\nof bulk MoS_2 in K can follow this model. We also find the effect of\ninter-layer spin-orbit coupling in triple-layer MoS2. In addition, the\ninter-layer spin-orbit coupling is found to become to be stronger under the\npressure and results in the decrease of main energy gap in the splitting\nvalance bands at K."
    },
    {
        "anchor": "Discovery and implications of hidden atomic-scale structure in a\n  metallic meteorite: Iron and its alloys have made modern civilisation possible, with metallic\nmeteorites providing one of the human's earliest sources of usable iron as well\nas providing a window into our solar system's billion-year history. Here\nhighest-resolution tools reveal the existence of a previously hidden FeNi\nnanophase within the extremely slowly cooled metallic meteorite NWA 6259. This\nnew nanophase exists alongside Ni-poor and Ni-rich nanoprecipitates within a\nmatrix of tetrataenite, the uniaxial, chemically ordered form of FeNi. The\nferromagnetic nature of the nanoprecipitates combined with the\nantiferromagnetic character of the FeNi nanophases give rise to a complex\nmagnetic state that evolves dramatically with temperature. These observations\nextend and possibly alter our understanding of celestial metallurgy, provide\nnew knowledge concerning the archetypal Fe-Ni phase diagram and supply new\ninformation for the development of new types of sustainable, technologically\ncritical high-energy magnets.",
        "positive": "Solid-like to Liquid-like Behavior of Cu Diffusion in Superionic Cu2X\n  (X=S, Se): An Inelastic Neutron Scattering and Ab-Initio Molecular Dynamics\n  Investigation: Cu2Se and Cu2S are excellent model systems of superionic conductors with\nlarge diffusion coefficients that have been reported to exhibit different\nsolid-liquid-like Cu-ion diffusion. In this paper, we clarify the atomic\ndynamics of these compounds with temperature-dependent ab-initio molecular\ndynamics (AIMD) simulations and inelastic neutron scattering (INS) experiments.\nUsing the dynamical structure factor and Van-Hove correlation function, we\ninterrogate the jump-time, hopping length distribution and associated diffusion\ncoefficients. In cubic-Cu2Se at 500 K, we find solid-like diffusion with\nCu-jump lengths matching well the first-neighbour Cu-Cu distance of ~3 {\\AA} in\nthe crystal, and clearly defined optic phonons involving Cu-vibrations. Above\n700 K, the jump-length distribution becomes a broad maximum cantered around 4\n{\\AA}, spanning the first and second neighbour lattice distances, and a\nconcurrent broadening of the Cu-phonon density of states. Further, above 900 K,\nthe Cu-diffusion becomes close to liquid-like, with distributions of Cu-atoms\ncontinuously connecting crystal sites, while the vibrational modes involving Cu\nmotions are highly damped, though still not fully over-damped as in a liquid.\nAt low temperatures, the solid-like diffusion is consistent with previous X-ray\ndiffraction and quasielastic neutron scattering experiments, while the\nhigher-temperature observation of the liquid-like diffusion is in agreement\nwith previous AIMD simulations. We also report AIMD simulations in Cu2S in the\nhexagonal and cubic superionic phases, and observe similar solid and\nliquid-like diffusion at low- and high-temperatures, respectively. The\ncalculated ionic-conductivity is in fair agreement with reported experimental\nvalues."
    },
    {
        "anchor": "Quantum-Matter Heterostructures: Combining the power and possibilities of heterostructure engineering with the\ncollective and emergent properties of quantum materials, quantum-matter\nheterostructures open a new arena of solid-state physics. Here we provide a\nreview of interfaces and heterostructures made of quantum matter. Unique\nelectronic states can be engineered in these structures, giving rise to\nunforeseeable opportunities for scientific discovery and potential\napplications. We discuss the present status of this nascent field of\nquantum-matter heterostructures, its limitations, perspectives, and challenges.",
        "positive": "Ferromagnetic ordering in dilute magnetic dielectrics with and without\n  free carriers: The state of art in the theoretical and experimental studies of transition\nmetal doped oxides (dilute magnetic dielectrics) is reviewed. The available\ndata show that the generic non-equilibrium state of oxide films doped with\nmagnetic impurities may either favor ferromagnetism with high Curie temperature\nor result in highly inhomogeneous state without long-range magnetic order. In\nboth case concomitant defects (vacancies, interstitial ions play crucial part."
    },
    {
        "anchor": "Nanomechanics of Advanced Polymer Fibres: The micro/nano-structural evolution before and after tensile/compressive\nloading, fatigue and ultimately, failure has been studied by Raman (and IR)\nmicrospectroscopy for PBO, PET, PA66, PP, silk and hair using three probes: low\nwavenumber collective modes at <150cm-1 as representative of the\ncrystalline/ordered and amorphous chains, stretching and bending modes, as\nrepresentative of the C-C/ C-N polymeric backbone, and localized vibrations\n(OH, NH) to probe the inter-macromolecule segment distance. Wavenumber and\nbandwidth distribution across fibre diameters reveal different types of\nskin/core heterogeneity. The in situ analysis at different strain/pressure\nlevels shows that amorphous chains in the fibre accommodate the stress\ndifferently. The post mortem analysis shows that amorphous domains can be higly\nstressed during the failure and remnant stress can be measured.",
        "positive": "Interplay of electron-electron and electron-phonon interactions in the\n  low temperature phase of 1T-TaS2: We investigate the interplay of the electron-electron and electron-phonon\ninteractions in the electronic structure of an exotic insulating state in the\nlayered dichalcogenide 1T-TaS2, where the charge-density-wave (CDW) order\ncoexists with a Mott correlation gap. Scanning tunneling microscopy and\nspectroscopy measurements with high spatial and energy resolution determine\nunambiguously the CDW and the Mott gap as 0.20-0.24 eV and 0.32 eV,\nrespectively, through the real space electron phases measured across the\nmultiply formed energy gaps. An unusual local reduction of the Mott gap is\nobserved on the defect site, which indicates the renormalization of the on-site\nCoulomb interaction by the electron-phonon coupling as predicted by the\nHubbard-Holstein model. The Mott-gap renormalization provides new insight into\nthe disorder-induced quasi-metallic phases of 1T-TaS2."
    },
    {
        "anchor": "Atomistic tight binding study of quantum confined Stark effect in\n  GaBi$_x$As$_{1-x}$/GaAs quantum wells: Recently, there has been tremendous research interest in novel bismide\nsemiconductor materials (such as GaBi$_x$As$_{1-x}$) for wavelength-engineered,\nlow-loss optoelectronic devices. We report a first study of the quantum\nconfined Stark effect (QCSE) computed for GaBi$_x$As$_{1-x}$/GaAs quantum well\n(QW) structures based on large-scale atomistic tight-binding calculations. A\ncomprehensive investigation of the QCSE as a function of the applied electric\nfield orientations and the QW Bi fractions reveals unconventional character of\nthe Stark shift at low Bi compositions ($x$=3.125\\%). This atypical QCSE is\nattributed to a strong confinement of the ground-state hole wave functions due\nto the presence of Bi clusters. At technologically-relevant large Bi fractions\n($\\geq$ 10\\%), the impact of Bi clustering on the electronic structure is found\nto be weak, leading to a quadratic Stark shift of the ground-state transition\nwavelength, similar to the previously observed Stark shift in other\nconventional III-V materials. Our results provide useful insights for the\nunderstanding of the electric field dependence of the electronic and optical\nproperties of GaBi$_x$As$_{1-x}$/GaAs QWs, and will be important for the design\nof devices in the optoelectronics and spintronics areas of research.",
        "positive": "Strong renormalization of the electronic band gap due to lattice\n  polarization in the GW formalism: The self-consistent GW band gaps are known to be significantly overestimated.\nWe show that this overestimation is, to a large extent, due to the neglect of\nthe contribution of the lattice polarization to the screening of the\nelectron-electron interaction. To solve this problem, we derive within the GW\nformalism a generalized plasmon-pole model that accounts for lattice\npolarization. The resulting GW self-energy is used to calculate the band\nstructures of a set of binary semiconductors and insulators. The lattice\ncontribution always decreases the band gap. The shrinkage increases with the\nsize of the longitudinal-transverse optical splitting and it can represent more\nthan 15% of the band gap in highly polar compounds, reducing the band-gap\npercentage error by a factor of three."
    },
    {
        "anchor": "Nucleation in Sessile Saline Microdroplets: Induction Time Measurement\n  via Deliquescence-Recrystallization Cycling: Induction time, a measure of how long one will wait for nucleation to occur,\nis an important parameter in quantifying nucleation kinetics and its underlying\nmechanisms. Due to the stochastic nature of nucleation, efficient methods for\nmeasuring large number of independent induction times are needed to ensure\nstatistical reproducibility. In this work, we present a novel approach for\nmeasuring and analyzing induction times in sessile arrays of microdroplets via\ndeliquescence/recrystallization cycling. With the help of a recently developed\nimage analysis protocol, we show that the interfering diffusion-mediated\ninteractions between microdroplets can be eliminated by controlling the\nrelative humidity, thereby ensuring independent nucleation events. Moreover,\npossible influence of heterogeneities, impurities, and memory effect appear\nnegligible as suggested by our 2-cycle experiment. Further statistical analysis\n(k-sample Anderson-Darling test) reveals that upon identifying possible\noutliers, the dimensionless induction times obtained from different datasets\n(microdroplet lines) obey the same distribution and thus can be pooled together\nto form a much larger dataset. The pooled dataset showed an excellent fit with\nthe Weibull function, giving a mean supersaturation at nucleation of 1.61 and\n1.85 for the 60pL and 4pL microdroplet respectively. This confirms the effect\nof confinement where smaller systems require higher supersaturations to\nnucleate. Both the experimental method and the data-treatment procedure\npresented herein offer promising routes in the study of fundamental aspects of\nnucleation kinetics, particularly confinement effects, and are adaptable to\nother salts, pharmaceuticals, or biological crystals of interest.",
        "positive": "Electrical and Thermal Transport Properties of the beta-Pyrochlore Oxide\n  CsW2O6: We report the electrical resistivity, thermoelectric power, and thermal\nconductivity of single-crystalline and sintered samples of the 5d pyrochlore\noxide CsW2O6. The electrical resistivity of the single crystal is 3 mohm cm at\n295 K and gradually increases with decreasing temperature above 215 K (Phase\nI). The thermoelectric power of the single-crystalline and sintered samples\nshows a constant value of approximately -60 uV K-1 in Phase I. These results\nreflect that the electron conduction by W 5d electrons in Phase I is incoherent\nand in the hopping regime, although a band gap does not open at the Fermi\nlevel. The thermal conductivity in Phase I of both samples is considerably low,\nwhich might be due to the rattling of Cs+ ions. In Phase II below 215 K, the\nelectrical resistivity and the absolute value of thermoelectric power of both\nsamples strongly increase with decreasing temperature, corresponding to a\ntransition to a semiconducting state with a band gap open at the Fermi level,\nwhile the thermal conductivity in Phase II is smaller than that in Phase I."
    },
    {
        "anchor": "Understanding and tuning magnetism in layered Ising-type antiferromagnet\n  FePSe3 for potential 2D magnet: Recent development in two-dimensional (2D) magnetic materials have motivated\nthe search for new van der Waals magnetic materials, especially Ising-type\nmagnets with strong magnetic anisotropy. Fe-based MPX3 (M = transition metal, X\n= chalcogen) compounds such as FePS3 and FePSe3 both exhibit an Ising-type\nmagnetic order, but FePSe3 receives much less attention compared to FePS3. This\nwork focuses on establishing the strategy to engineer magnetic anisotropy and\nexchange interactions in this less-explored compound. Through chalcogen and\nmetal substitutions, the magnetic anisotropy is found to be immune against S\nsubstitution for Se whereas tunable only with heavy Mn substitution for Fe. In\nparticular, Mn substitution leads to a continuous rotation of magnetic moments\nfrom the out-of-plane direction towards in-plane. Furthermore, the magnetic\nordering temperature displays non-monotonic doping dependence for both\nchalcogen and metal substitutions but due to different mechanisms. These\nfindings provide deeper insight into the Ising-type magnetism in this important\nvan der Waals material, shedding light on the study of other Ising-type\nmagnetic systems as well as discovering novel 2D magnets for potential\napplications in spintronics.",
        "positive": "AI powered, automated discovery of polymer membranes for carbon capture: The generation of molecules with Artificial Intelligence (AI) is poised to\nrevolutionize materials discovery. Potential applications range from\ndevelopment of potent drugs to efficient carbon capture and separation\ntechnologies. However, existing computational frameworks lack automated\ntraining data creation and physical performance validation at meso-scale where\ncomplex properties of amorphous materials emerge. The methodological gaps have\nso far limited AI design to small-molecule applications. Here, we report the\nfirst automated discovery of complex materials through inverse molecular design\nwhich is informed by meso-scale target features and process figures-of-merit.\nWe have entered the new discovery regime by computationally generating and\nvalidating hundreds of polymer candidates designed for application in\npost-combustion carbon dioxide filtration. Specifically, we have validated each\ndiscovery step, from training dataset creation, via graph-based generative\ndesign of optimized monomer units, to molecular dynamics simulation of gas\npermeation through the polymer membranes. For the latter, we have devised a\nRepresentative Elementary Volume (REV) enabling permeability simulations at\nabout 1,000x the volume of an individual, AI-generated monomer, obtaining\nquantitative agreement. The discovery-to-validation time per polymer candidate\nis on the order of 100 hours in a standard computing environment, offering a\ncomputational screening alternative prior to lab validation."
    },
    {
        "anchor": "Dopant-segregation to grain boundaries controls electrical conductivity\n  of n-type NbCo(Pt)Sn half-Heusler alloy mediating thermoelectric performance: Science-driven design of future thermoelectric materials requires a deep\nunderstanding of the fundamental relationships between microstructure and\ntransport properties. Grain boundaries in polycrystalline materials influence\nthe thermoelectric performance through the scattering of phonons or the\ntrapping of electrons due to space-charge effects. Yet, the current lack of\ncareful investigations on grain boundary-associated features hinders further\noptimization of properties. Here, we study n-type NbCo1-xPtxSn half-Heusler\nalloys, which were synthesized by ball milling and spark plasma sintering\n(SPS). Post-SPS annealing was performed on one sample, leading to improved\nlow-temperature electrical conductivity. The microstructure of both samples was\nexamined by electron microscopy and atom probe tomography. The grain size\nincreases from ~230 nm to ~2.38 {\\mu}m upon annealing. Pt is found within\ngrains and at grain boundaries, where it locally reduces the resistivity, as\nassessed by in situ four-point-probe electrical conductivity measurement. Our\nwork showcases the correlation between microstructure and electrical\nconductivity, providing opportunities for future microstructural optimization\nby tuning the chemical composition at grain boundaries.",
        "positive": "Nucleation of dislocations and their dynamics in layered oxides cathode\n  materials during battery charging: Defects and their interactions in crystalline solids often underpin material\nproperties and functionality as they are decisive for stability, result in\nenhanced diffusion, and act as a reservoir of vacancies. Recently, lithium-rich\nlayered oxides have emerged among the leading candidates for the\nnext-generation energy storage cathode material, delivering 50 % excess\ncapacity over commercially used compounds. Oxygen-redox reactions are believed\nto be responsible for the excess capacity, however, voltage fading has\nprevented commercialization of these new materials. Despite extensive research\nthe understanding of the mechanisms underpinning oxygen-redox reactions and\nvoltage fade remain incomplete. Here, using operando three-dimensional Bragg\ncoherent diffractive imaging, we directly observe nucleation of a mobile\ndislocation network in nanoparticles of lithium-rich layered oxide material.\nSurprisingly, we find that dislocations form more readily in the lithium-rich\nlayered oxide material as compared with a conventional layered oxide material,\nsuggesting a link between the defects and the anomalously high capacity in\nlithium-rich layered oxides. The formation of a network of partial dislocations\ndramatically alters the local lithium environment and contributes to the\nvoltage fade. Based on our findings we design and demonstrate a method to\nrecover the original high voltage functionality. Our findings reveal that the\nvoltage fade in lithium-rich layered oxides is reversible and call for new\nparadigms for improved design of oxygen-redox active materials."
    },
    {
        "anchor": "The shifts X-Ray Mn K\u03b1 and 2p spectra of Mn-Heusler alloys: X-ray emission K{\\alpha}1,2 spectra of Mn in Heusler alloys Co2MnMe (Me = Al,\nGa, Sb), Ni2MnIn, Cu2MnAl were studied. Shifts of Mn K{\\alpha}1,2 lines\nrelatively pure Mn in high-energy region and low-energy shifts of binding\nenergy Mn 2p XPS is detected. X-ray emission and XPS shifts are in qualitative\nagreement.",
        "positive": "Grand-canonical Monte-Carlo simulation methods for charge-decorated\n  cluster expansions: Monte-Carlo sampling of lattice model Hamiltonians is a well-established\ntechnique in statistical mechanics for studying the configurational entropy of\ncrystalline materials. When species to be distributed on the lattice model\ncarry charge, the charge balance constraint on the overall system prohibits\nsingle-site Metropolis exchanges in MC. In this article, we propose two methods\nto perform MC sampling in the grand-canonical ensemble in the presence of a\ncharge-balance constraint. The table-exchange method (TE) constructs small\ncharge-conserving excitations, and the square-charge bias method (SCB) allows\nthe system to temporarily drift away from charge neutrality. We illustrate the\neffect of internal hyper-parameters on the efficiency of these algorithms and\nsuggest practical strategies on how to apply these algorithms to real\napplications."
    },
    {
        "anchor": "Fast Dynamics in a Model Metallic Glass-forming Material: We investigate the fast $\\beta$- and Johari-Goldstein (JG) $\\beta$-relaxation\nprocesses, along with the elastic scattering response of glass-forming (GF)\nliquids and the Boson peak, in a simulated Al-Sm GF material exhibiting a\nfragile-strong (FS) transition. These dynamical processes are universal in\n'ordinary' GF fluids and collectively describe their 'fast dynamics', and we\nfind these relaxation processes also arise in a GF liquid exhibiting a\nfragile-strong transition. String-like particle motion, having both an\nirreversible and reversible nature ('stringlets') component, occurs in the\nfast-dynamics regime, corresponding to a ps timescale. String-like collective\nmotion associated with localized unstable modes facilitate irreversible and\nintermittent particle 'jumping' events at long times associated with the JG\n$\\beta$-relaxation process, while stringlets associated with localized stable\nmodes and corresponding perfectly reversible atomic motion give rise to the\nBoson peak. To further clarify the origin of the Boson peak, we calculate the\ndensity of states for both the stringlet particles and the 'normal' particles\nand find that the stringlet particles give rise to a Boson peak while the\nnormal atoms do not. The growth of stringlets upon heating ultimately also\nleads to the 'softening' of these excitations, and the Boson peak frequency and\nshear modulus drop in concert with this softening. The growth of string-like\ncollective motion upon heating in the fast-dynamics regime is further shown to\nbe responsible for the growth in the intensity of the fast relaxation process.\nRelaxation in cooled liquids clearly involves a hierarchy of relaxation\nprocesses acting on rather different time and spatial scales.",
        "positive": "Impact of Boron doping to the tunneling magnetoresistance of Heusler\n  alloy Co2FeAl: Heusler alloys based magnetic tunnel junctions can potentially provide high\nmagnetoresistance, small damping and fast switching. Here junctions with\nCo2FeAl as a ferromagnetic electrode are fabricated by room temperature\nsputtering on Si/SiO2 substrates. The doping of Boron in Co2FeAl is found to\nhave a large positive impact on the structural, magnetic and transport\nproperties of the junctions, with a reduced interfacial roughness and\nsubstantial improved tunneling magnetoresistance. A two-level magnetoresistance\nis also observed in samples annealed at low temperature, which is believed to\nbe related to the memristive effect of the tunnel barrier with impurities."
    },
    {
        "anchor": "Electrochemical Oxygen Intercalation into Sr$_2$IrO$_4$: Oxygen was electrochemically intercalated into Sr$_2$IrO$_4$ sintered\nsamples, single crystals and a thin film. We estimate the diffusion length to a\nfew $\\mu$m and the concentration of the intercalated oxygen to $\\delta$\n$\\simeq$ 0.01. The latter is thus much smaller than for the cuprate and\nnickelate parent compounds, for which $\\delta$ $>$ 0.1 is obtained, which could\nbe a consequence of larger steric effects. The influence of the oxygen doping\nstate on resistivity is small, indicating also a poor charge transfer to the\nconduction band. It is shown that electrochemical intercalation of oxygen may\nalso contribute to doping, when gating thin films with ionic liquid in the\npresence of water.",
        "positive": "Controllable phase transitions between multiple charge density waves in\n  monolayer 1T-VSe$_2$ via doping and strain engineering: Two-dimensional (2D) materials are known to possess emergent properties that\nare not found in their bulk counterparts. Recent experiments have shown a\n$\\sqrt7 \\times \\sqrt3$ charge density wave (CDW) in monolayer 1T-VSe$_2$, in\ncontrast to the $4\\times 4\\times 3$ phase in bulk. Here, via first-principles\ncalculations, we show that multiple CDW phases compete in monolayer VSe$_2$,\nthe ground state of which can be tuned by charge doping and in-plane biaxial\nstrain. With doping, the $\\sqrt7 \\times \\sqrt3$ CDW of the pristine VSe$_2$\ntransfers to a $3 \\times \\sqrt3$ and $4\\times 4$ phase, the latter of which is\na projection of the bulk counterpart, at critical doping concentrations of\naround 0.2 holes per formula unit and 0.25 electrons per formula unit,\nrespectively. The $4\\times 4$ CDW phase can also be stabilized under\ncompressive strain. Although electron-phonon coupling is prevailing in the CDW\nformation, we show that Fermi surface nesting is a good starting point to\nexplain most of these transitions in monolayer 1T-VSe$_2$. These results make\nVSe$_2$ an appealing material for electronic devices based on controllable CDW\nphase transitions."
    },
    {
        "anchor": "Fabrication of nanopatterned DNA films by Langmuir-Blodgett technique: Fractal-like nanopatterned DNA thin films have been fabricated on mica\nsubstrate by Langmuir-Blodgett (LB) technique. Structures and components of DNA\nnanopatterns were investigated using atomic force microscopy (AFM) and X-ray\nphotoelectron spectroscopy (XPS). The effect of surface pressure on the\ntransferred DNA composite films has been studied. Scanning force microscopic\nobservations revealed that the surface structure and morphology of DNA\nnanopatterns can be well controlled by changing the surface pressure. The\ngrowth mechanism of the fractal-like nanopatterns is discussed in terms of the\ndiffusion-limited aggregation (DLA) model. The formation of large-scale DNA\nnetworks provided a well-defined template for the construction of nanocomposite\nfilms. Patterns of silver metal were prepared on DNA networks by subsequent\nmetallization process.",
        "positive": "Crossover between Photochemical and Photothermal Oxidations of\n  Atomically Thin Magnetic Semiconductor CrPS4: Many two-dimensional (2D) semiconductors represented by transition metal\ndichalcogenides have tunable optical bandgaps in the visible or near IR-range\nstanding as a promising candidate for optoelectronic devices. Despite this\npotential, however, their photoreactions are not well understood or\ncontroversial in the mechanistic details. In this work, we report a unique\nthickness-dependent photoreaction sensitivity and a switchover between two\ncompeting reaction mechanisms in atomically thin chromium thiophosphate\n(CrPS4), a two-dimensional antiferromagnetic semiconductor. CrPS4 showed a\nthreshold power density 2 orders of magnitude smaller than that for MoS2\nobeying a photothermal reaction route. In addition, reaction cross section\nquantified with Raman spectroscopy revealed distinctive power dependences in\nthe low and high power regimes. On the basis of optical in situ thermometric\nmeasurements and control experiments against O2, water, and photon energy, we\nproposed a photochemical oxidation mechanism involving singlet O2 in the low\npower regime with a photothermal route for the other. We also demonstrated a\nhighly effective encapsulation with Al2O3 as a protection against the\ndestructive photoinduced and ambient oxidations."
    },
    {
        "anchor": "The Geometry of Niggli Reduction II: BGAOL -- Embedding Niggli Reduction: Niggli reduction can be viewed as a series of operations in a six-dimensional\nspace derived from the metric tensor. An implicit embedding of the space of\nNiggli-reduced cells in a higher dimensional space to facilitate calculation of\ndistances between cells is described. This distance metric is used to create a\nprogram, BGAOL, for Bravais lattice determination. Results from BGAOL are\ncompared to the results from other metric-based Bravais lattice determination\nalgorithms.",
        "positive": "Atomistic modelling of large-scale metal film growth fronts: We present simulations of metallization morphologies under ionized sputter\ndeposition conditions, obtained by a new theoretical approach. By means of\nmolecular dynamics simulations using a carefully designed interaction\npotential, we analyze the surface adsorption, reflection, and etching reactions\ntaking place during Al physical vapor deposition, and calculate their relative\nprobability. These probabilities are then employed in a feature-scale\ncellular-automaton simulator, which produces calculated film morphologies in\nexcellent agreement with scanning-electron-microscopy data on ionized sputter\ndeposition."
    },
    {
        "anchor": "Lattice dynamics of FeSb2: The lattice dynamics of FeSb2 is investigated by the first-principles DFT\ncalculations and Raman spectroscopy. All Raman and infra-red active phonon\nmodes are properly assigned. The calculated and measured phonon energies are in\ngood agreement except for the B3g symmetry mode. We have observed strong mixing\nof the Ag symmetry modes, with the intensity exchange in the temperature range\nbetween 210 K and 260 K. The Ag modes repulsion increases by doping FeSb2 with\nCo. There are no signatures of the electron-phonon interaction for these modes.",
        "positive": "Localized High-Concentration Electrolytes Get More Localized Through\n  Micelle-Like Structures: Liquid electrolytes in batteries are typically treated as macroscopically\nhomogeneous ionic transport media despite having complex chemical composition\nand atomistic solvation structures, leaving a knowledge gap of microstructural\ncharacteristics. Here, we reveal a unique micelle-like structure in a localized\nhigh-concentration electrolyte (LHCE), in which the solvent acts as a\nsurfactant between an insoluble salt in diluent. The miscibility of the solvent\nwith the diluent and simultaneous solubility of the salt results in a\nmicelle-like structure with a smeared interface and an increased salt\nconcentration at the centre of the salt-solvent clusters that extends the salt\nsolubility. These intermingling miscibility effects have temperature\ndependencies, wherein an exemplified LHCE peaks in localized cluster salt\nconcentration near room temperature and is utilized to form a stable\nsolid-electrolyte interphase (SEI) on Li-metal anode. These findings serve as a\nguide to predicting a stable ternary phase diagram and connecting the\nelectrolyte microstructure with electrolyte formulation and formation protocols\nto form stable SEI for enhanced battery cyclability."
    },
    {
        "anchor": "Does hybrid density functional theory predict a non-magnetic ground\n  state for delta-Plutonium?: Hybrid density functionals, which replaces a fraction of density functional\ntheory (DFT) exchange with exact Hartree-Fock (HF) exchange, have been used to\nstudy the structural, magnetic, and electronic properties of delta-Plutonium.\nThe fractions of exact Hartree-Fock exchange used were 25%, 40%, and 55%.\nCompared to the pure PBE functional, the lattice constants expanded with\nrespect to the experimental value when the PBE-HF hybrid functionals were\napplied. A non-magnetic ground state was realized for 55% HF contribution;\notherwise the ground state was anti-ferromagnetic. The 5f electrons tend to\nexhibit slight delocalization or itinerancy for the pure PBE functional and\nwell-defined localization for the hybrid functionals, with the degree of 5f\nelectron localization increasing with the amount of HF exchange. Overall, the\nperformance of the hybrid density functionals do not seem superior to pure\ndensity functionals for delta-Plutonium.",
        "positive": "Thermodynamic Screening of Metal-Substituted MOFs for Carbon Capture: Metal-organic frameworks (MOFs) have emerged as promising materials for\ncarbon capture applications due to their high CO2 capacities and tunable\nproperties. Amongst the many possible MOFs, metal-substituted compounds based\non M-DOBDC and M-HKUST-1 have demonstrated amongst the highest CO2 capacities\nat the low pressures typical of flue gasses. Here we explore the possibility\nfor additional performance tuning of these compounds by computationally\nscreening 36 metal-substituted variants (M = Be, Mg, Ca, Sr, Sc, Ti, V, Cr, Mn,\nFe, Co, Ni, Cu, Zn, Mo, W, Sn, and Pb) with respect to their CO2 adsorption\nenthalpy, $\\Delta$H (T=300K). Supercell calculations based on van der Waals\ndensity functional theory (vdW-DF) yield enthalpies in good agreement with\nexperimental measurements, out-performing semi-empirical (DFT-D2) and\nconventional (LDA and GGA) functionals. Our screening identifies 13 compounds\nhaving $\\Delta$H values within the targeted thermodynamic window 40 $\\leq$\n$\\Delta$H $\\leq$ 75 kJ/mol: 8 are based on M-DODBC (M=Mg, Ca, Sr, Sc, Ti, V,\nMo, and W), and 5 on M-HKUST-1 (M= Be, Mg, Ca, Sr and Sc). Variations in the\nelectronic structure and the geometry of the structural building unit are\nexamined and used to rationalize trends in CO2 affinity. In particular, the\npartial charge on the coordinatively unsaturated metal sites is found to\ncorrelate with $\\Delta$H, suggesting that this property may be used as a simple\nperformance descriptor. The ability to rapidly distinguish promising MOFs from\nthose that are \"thermodynamic dead-ends\" will be helpful in guiding synthesis\nefforts towards promising compounds."
    },
    {
        "anchor": "Analysis of Lithiation and Delithiation Kinetics in Silicon: Analysis of lithiation and delithiation kinetics in pulse-laser-deposited\ncrystalline thin-film silicon (Si) electrodes is presented. Data from\nopen-circuit relaxation experiments are used in conjunction with a model based\non Tafel kinetics and double-layer capacitance to estimate the apparent\ntransfer coefficients ({\\alpha}a, {\\alpha}c), and exchange current density to\ncapacitance ratio (i0/Cdl) for lithiation and delithiation reactions in a\nlithiated silicon (LixSi) system. Parameters estimated from data sets obtained\nduring first-cycle amorphization of crystalline Si, as well as from cycled\ncrystalline Si and amorphous Si thin-film electrodes do not show much\nvariation, indicating that they are intrinsic to lithiation/delithiation in Si.\nA methodology to estimate the side-reaction rate and its role in the evolution\nof the open-circuit potential of the LixSi system are discussed. We conclude\nthat the large potential offset between lithiation and delithiation reactions\nat any given state of charge is partially caused by a large kinetic resistance\n(i.e., small i0). Using the estimated parameters, the model is shown to predict\nsuccessfully the behavior of the system under galvanostatic lithiation and\ndelithiation.",
        "positive": "Degradation model of high-nickel positive electrodes: Effects of loss of\n  active material and cyclable lithium on capacity fade: Nickel-rich layered oxides have been widely used as positive electrode\nmaterials for high-energy-density lithium-ion batteries, but their degradation\nhas severely affected cell performance, in particular at a high voltage and\ntemperature. However, the underlying degradation mechanisms have not been well\nunderstood due to the complexity and lack of predictive models.Here we present\na model at the particle level to describe the structural degradation caused by\nphase transition in terms of loss of active material (LAM), loss of lithium\ninventory (LLI), and resistance increase. The particle degradation model is\nthen incorporated into a cell-level P2D model to explore the effects of LAM and\nLLI on capacity fade in cyclic ageing tests. It is predicted that the loss of\ncyclable lithium (trapped in the degraded shell) leads to a shift in the\nstoichiometry range of the negative electrode but does not directly contribute\nto the capacity loss, and that the loss of positive electrode active materials\ndominates the fade of usable cell capacity in discharge. The available capacity\nat a given current rate is further decreased by the additional resistance of\nthe degraded shell layer. The change pattern of the state-of-charge curve\nprovides information of more dimensions than the conventional capacity-fade\ncurve, beneficial to the diagnosis of degradation modes. The model has been\nimplemented into PyBaMM and made available as open source codes."
    },
    {
        "anchor": "Photoluminescence investigations of 2D hole Landau levels in p-type\n  single Al_{x}Ga_{1-x}As/GaAs heterostructures: We study the energy structure of two-dimensional holes in p-type single\nAl_{1-x}Ga_{x}As/GaAs heterojunctions under a perpendicular magnetic field.\nPhotoluminescence measurments with low densities of excitation power reveal\nrich spectra containing both free and bound-carrier transitions. The\nexperimental results are compared with energies of valence-subband Landau\nlevels calculated using a new numerical procedure and a good agreement is\nachieved. Additional lines observed in the energy range of free-carrier\nrecombinations are attributed to excitonic transitions. We also consider the\nrole of many-body effects in photoluminescence spectra.",
        "positive": "Structural, Elastic, Electronic and Optical Properties of $Be_2X(X=C,\n  Si, Ge, Sn)$: First Principle Study: We computed structural, elastic, electronic and optical properties of Be2X(X\n= C; Si; Ge; Sn) family of antiuorite with ab initio DFT calculations using the\ngeneralized gradient approximation (GGA). The different parameters such as\ngeometry optimization, band structure, density of states, elastic constants,\ndielectric functions have been studied. We also calculated bandgap using PBE0\nand HSE hybrid functionals to compare experimental bandgap of Be2C. Although\nthree of the compounds are hypothetical in nature, their formation energy found\nto be negative. The calculated values of elastic constants indicates antiuorite\nBe2X are mechanically stable. The graph of real part of epsilon shows negative\nvalue giving promising resultfor blanket behaviour of Be2X from radiation\ndamage."
    },
    {
        "anchor": "Magnetically-defined topological edge plasmons in edgeless electron gas: Topological materials bear gapped excitations in bulk yet protected gapless\nexcitations at boundaries. Magnetoplasmons (MPs), as high-frequency density\nexcitations of two-dimensional electron gas (2DEG) in a perpendicular magnetic\nfield, embody a prototype of band topology for bosons. The\ntime-reversal-breaking magnetic field opens a topological gap for bulk MPs up\nto the cyclotron frequency; topologically-protected edge magnetoplasmons (EMPs)\nbridge the bulk gap and propagate unidirectionally along system's boundaries.\nHowever, all the EMPs known to date adhere to physical edges where the electron\ndensity terminates abruptly. This restriction has made device application\nextremely difficult. Here we demonstrate a new class of topological edge\nplasmons -- domain-boundary magnetoplasmons (DBMPs), within a uniform edgeless\n2DEG. Such DBMPs arise at the domain boundaries of an engineered sign-changing\nmagnetic field and are protected by the difference of gap Chern numbers (+/-1)\nacross the magnetic domains. They propagate unidirectionally along the domain\nboundaries and are immune to domain defects. Moreover, they exhibit wide\ntunability in the microwave frequency range under an applied magnetic field or\ngate voltage. Our study opens a new direction to realize high-speed\nreconfigurable topological devices.",
        "positive": "Tunable transmission due to defects in zigzag phosphorene nanoribbons: Transport of the edge-state electrons along zigzag phosphorene nanoribbons in\npresence of two impurities/vacancies is analytically investigated. Considering\nthe places of the defects, a number of different situations are examined. When\nboth defects are placed on the edge zigzag chain, as is expected, with changing\nthe energy of the traveling electrons the electrical conductance exhibits a\nresonance behavior. In this case, for two vacancies the observed resonant peaks\nbecome extremely sharp. An amazing behavior is seen when the second vacancy is\nlocated along an armchair chain while the first is placed at the intersection\nof the edge zigzag and this armchair chains. In this case, in a considerable\nrange of energy, the conductance is strongly strengthened. In fact the presence\nof the second vacancy create a shielded region around the first vacancy,\nconsequently, the traveling wave bypasses this region and enhances the\nconductivity. The analytical results are compared with numerical simulations\nshowing a very good agreement."
    },
    {
        "anchor": "Capillary fluctuations of surface steps: An atomistic simulation study\n  for the model Cu(111) system: Molecular dynamics (MD) simulations are employed to investigate the capillary\nfluctuations of steps on the surface of a model metal system. The fluctuation\nspectrum, characterized by the wave number ($k$) dependence of the mean squared\ncapillary-wave amplitudes and associated relaxation times, is calculated for\n$\\left<110\\right>$ and $\\left<112\\right>$ steps on the $\\{111\\}$ surface of\nelemental copper near the melting temperature of the classical potential model\nconsidered. Step stiffnesses are derived from the MD results, yielding values\nfrom the largest system sizes of $(37\\pm1) \\,\n\\mathrm{meV}/\\mathring{\\mathrm{A}}$ for the different line orientations,\nimplying that the stiffness is isotropic within the statistical precision of\nthe calculations. The fluctuation lifetimes are found to vary by approximately\nfour orders of magnitude over the range of wave numbers investigated,\ndisplaying a $k$ dependence consistent with kinetics governed by step-edge\nmediated diffusion. The values for step stiffness derived from these\nsimulations are compared to step free energies for the same system and\ntemperature obtained in a recent MD-based thermodynamic-integration (TI) study\n[Freitas, Frolov, and Asta, Phys. Rev. B 95, 155444 (2017)]. Results from the\ncapillary-fluctuation analysis and TI calculations yield statistically\nsignificant differences that are discussed within the framework of\nstatistical-mechanical theories for configurational contributions to step free\nenergies.",
        "positive": "Spin Glass-like Phase below ~ 210 K in Magnetoelectric Gallium Ferrite: In this letter we show the presence of a spin-glass like phase in single\ncrystals of magnetoelectric gallium ferrite (GaFeO3) below ~210 K via\ntemperature dependent ac and dc magnetization studies. Analysis of frequency\ndispersion of the susceptibility peak at ~210 K using the critical slowing down\nmodel and Vogel-Fulcher law strongly suggests the existence of a classical\nspin-glass like phase. This classical spin glass behavior of GaFeO3 is\nunderstood in terms of an outcome of geometrical frustration arising from the\ninherent site disorder among the antiferromagnetically coupled Fe ions located\nat octahedral Ga and Fe sites."
    },
    {
        "anchor": "Mott- versus Slater-type Insulating Nature of Two-Dimensional Sn Atom\n  Lattice on SiC(0001): Semiconductor surfaces with narrow surface bands provide unique playgrounds\nto search for Mott-insulating state. Recently, a combined experimental and\ntheoretical study [Phys. Rev. Lett. 114, 247602 (2015)] of the two-dimensional\n(2D) Sn atom lattice on a wide-gap SiC(0001) substrate proposed a Mott-type\ninsulator driven by strong on-site Coulomb repulsion U. Our systematic\ndensity-functional theory (DFT) study with local, semilocal, and hybrid\nexchange-correlation functionals shows that the Sn dangling-bond state largely\nhybridizes with the substrate Si 3p and C 2p states to split into three surface\nbands due to the crystal field. Such a hybridization gives rise to the\nstabilization of the antiferromagnetic order via superexchange interactions.\nThe band gap and the density of states predicted by the hybrid DFT calculation\nagree well with photoemission data. Our findings not only suggest that the\nSn/SiC(0001) system can be represented as a Slater-type insulator driven by\nlong-range magnetism, but also have an implication that taking into account\nlong-range interactions beyond the on-site interaction would be of importance\nfor properly describing the insulating nature of Sn/SiC(0001).",
        "positive": "Maximal predictability approach for identifying the right descriptors\n  for electrocatalytic reactions: Density Functional Theory (DFT) calculations are being routinely used to\nidentify new material candidates that approach activity near fundamental limits\nimposed by thermodynamics or scaling relations. DFT calculations have finite\nuncertainty and this raises an issue related to the ability to delineate\nmaterials that possess high activity. With the development of error estimation\ncapabilities in DFT, there is an urgent need to propagate uncertainty through\nactivity prediction models. In this work, we demonstrate a rigorous approach to\npropagate uncertainty within thermodynamic activity models. This maps the\ncalculated activity into a probability distribution, and can be used to\ncalculate the expectation value of the distribution, termed as the expected\nactivity. We prove that the ability to distinguish materials increases with\nreducing uncertainty. We define a quantity, prediction efficiency, which\nprovides a precise measure of the ability to distinguish the activity of\nmaterials for a reaction scheme over an activity range. We demonstrate the\nframework for 4 important electrochemical reactions, hydrogen evolution,\nchlorine evolution, oxygen reduction and oxygen evolution. We argue that future\nstudies should utilize the expected activity and prediction efficiency to\nimprove the likelihood of identifying material candidates that can possess high\nactivity."
    },
    {
        "anchor": "Pressure induced high-spin to low-spin transition in FeS evidenced by\n  x-ray emission spectroscopy: We report the observation of the pressure-induced high-spin to low-spin\ntransition in FeS using new high-pressure synchrotron x-ray emission\nspectroscopy techniques. The transition is evidenced by the disappearance of\nthe low-energy satellite in the Fe K$\\beta$ emission spectrum of FeS. Moreover,\nthe phase transition is reversible and closely related to the structural phase\ntransition from a manganese phosphide-like phase to a monoclinic phase. The\nstudy opens new opportunities for investigating the electronic properties of\nmaterials under pressure.",
        "positive": "The interplay of large two-magnon ferromagnetic resonance linewidths and\n  low Gilbert damping in Heusler thin films: We report on broadband ferromagnetic resonance linewidth measurements\nperformed on epitaxial Heusler thin films. A large and anisotropic two-magnon\nscattering linewidth broadening is observed for measurements with the\nmagnetization lying in the film plane, while linewidth measurements with the\nmagnetization saturated perpendicular to the sample plane reveal low Gilbert\ndamping constants of $(1.5\\pm0.1)\\times 10^{-3}$, $(1.8\\pm0.2)\\times 10^{-3}$,\nand $<8\\times 10^{-4}$ for Co$_2$MnSi/MgO, Co$_2$MnAl/MgO, and Co$_2$FeAl/MgO,\nrespectively. The in-plane measurements are fit to a model combining Gilbert\nand two-magnon scattering contributions to the linewidth, revealing a\ncharacteristic disorder lengthscale of 10-100 nm."
    },
    {
        "anchor": "Nucleation of Graphene on SiC(0001): This paper has been withdrawn due to the adherance to the double submission\npolicies of a refereed journal. Our apologies.",
        "positive": "Crystal and magnetic structures of $R_2$Ni$_2$In compounds ($R$ = Tb and\n  Ho): Crystal and magnetic structures of $R_2$Ni$_2$In ($R$ = Tb and Ho) have been\nstudied by powder neutron diffraction at low temperatures. The compounds\ncrystallize in an orthorhombic crystal structure of the Mn$_2$AlB$_2$-type. At\nlow temperatures, the magnetic moments localized solely on the rare earth atoms\nform antiferromagnetic structures. The Tb magnetic moments, equal to 8.65(6)\n$\\mu_B$ and parallel to the $c$-axis, form a collinear magnetic structure\ndescribed by the propagation vector $\\boldsymbol{k} = [\\frac{1}{2},\n\\frac{1}{2}, \\frac{1}{2}]$. This magnetic structure is stable up to the N\\'eel\ntemperature equal to 40 K. For Ho$_2$Ni$_2$In a complex, temperature-dependent\nmagnetic structure is detected. In the temperature range 3.5-8.6 K, an\nincommensurate magnetic structure, described by the propagation vector\n$\\boldsymbol{k}_1 = [0.76, 0, 0.52]$ is observed, while in the temperature\ninterval 2.2-3.1 K the magnetic order is described by two propagation vectors,\nnamely, $\\boldsymbol{k}_2 = [\\frac{5}{6}, 0.16, \\frac{1}{2}]$ and its third\nharmonics $3\\boldsymbol{k}_2 = [\\frac{5}{2}, 0.48, \\frac{3}{2}]$. Below 2 K, a\ncoexistence of all magnetic structures detected at higher temperatures is\nobserved. For all magnetic phases, the Ho magnetic moments are parallel to the\n$c$-axis. The low temperature heat capacity data confirm a first order\ntransition near 3 K."
    },
    {
        "anchor": "Applicability of scaling behavior and power laws in the analysis of the\n  magnetocaloric effect in second-order phase transition materials: In recent years, universal scaling has gained renewed attention in the study\nof magnetocaloric materials. It has been applied to a wide variety of pure\nelements and compounds, ranging from rare earth-based materials to transition\nmetal alloys, from bulk crystalline samples to nanoparticles. It is therefore\nnecessary to quantify the limits within which the scaling laws would remain\napplicable for magnetocaloric research. For this purpose, a threefold approach\nhas been followed: a) the magnetocaloric responses of a set of materials with\nCurie temperatures ranging from 46 to 336 K have been modeled with a mean-field\nBrillouin model, b) experimental data for Gd has been analyzed, and c) a\n3D-Ising model ---which is beyond the mean-field approximation--- has been\nstudied. In this way we can demonstrate that the conclusions extracted in this\nwork are model-independent. It is found that universal scaling remains\napplicable up to applied fields which provide a magnetic energy to the system\nup to 8\\% of the thermal energy at the Curie temperature. In this range, the\npredicted deviations from scaling laws remain below the experimental error\nmargin of carefully performed experiments. Therefore, for materials whose Curie\ntemperature is close to room temperature, scaling laws at the Curie temperature\nwould be applicable for the magnetic field range available at conventional\nmagnetism laboratories ($\\sim 10$ T), well above the fields which are usually\navailable for magnetocaloric devices.",
        "positive": "Hydrogen-Related Conversion Processes of Ge-Related Point Defects in\n  Silica Triggered by UV Laser Irradiation: The conversion processes of Ge-related point defects triggered in amorphous\nSiO2 by 4.7eV laser exposure were investigated. Our study has focused on the\ninterplay between the (=Ge&#8226;-H) H(II) center and the twofold coordinated\nGe defect (=Ge&#8226;&#8226;). The former is generated in the post-irradiation\nstage, while the latter decays both during and after exposure. The\npost-irradiation decay kinetics of =Ge&#8226;&#8226; is isolated and found to\nbe anti-correlated to the growth of H(II), at least at short times. From this\nfinding it is suggested that both processes are due to trapping of radiolytic\nH0 at the diamagnetic defect site. Furthermore, the anti-correlated behavior is\npreserved also under repeated irradiation: light at 4.7eV destroys the already\nformed H(II) centers and restore their precursors =Ge&#8226;&#8226;. This\nprocess leads to repeatability of the post-irradiation kinetics of the two\nspecies after multiple laser exposures. A comprehensive scheme of chemical\nreactions explaining the observed post-irradiation processes is proposed and\ntested against experimental data."
    },
    {
        "anchor": "Structural Feature in Dynamical Processes Accelerated Transition State\n  Calculations: Minimum energy path (MEP) search is a vital but often very time-consuming\nmethod to predict the transition states of versatile dynamic processes in\nchemistry, physics, and materials science. In this study, we reveal that the\nchemical bond lengths in the MEP structures, including those directly involved\nin the dynamical processes, largely resemble those in the stable initial and\nfinal states. Based on this discovery, we propose an adaptive semi-rigid body\napproximation (ASRBA) to construct a physically reasonable initial guess for\nthe MEP structures, which can be further optimized by the nudged elastic band\nmethod. Examination of several distinct dynamical processes in bulk, on crystal\nsurface, and through two-dimensional system show that the transition state\ncalculations based on the ASRBA results are robust and significantly faster\nthan those based on the popular linear interpolation and image-dependent pair\npotential methods.",
        "positive": "Tuning the spontaneous exchange bias effect with Ba to Sr partial\n  substitution in La$_{1.5}$(Sr$_{0.5-x}$Ba$_{x}$)CoMnO$_{6}$: The spontaneous exchange bias (SEB) effect is a remarkable phenomenon\nrecently observed in some reentrant spin-glass materials. Here we investigate\nthe SEB in La$_{1.5}$(Sr$_{0.5-x}$Ba$_{x}$)CoMnO$_{6}$ double-perovskites, a\nsystem with multifarious magnetic phases for which a notable increase in the\nexchange bias field is observed for intermediate Sr/Ba concentrations. The Ba\nto Sr substitution leads to the enhancement of the crystal lattice, which is\naccompanied by the raise of both the effective magnetic moment ($\\mu_{eff}$)\nand the antiferromagnetic (AFM) transition temperature that is observed below\nthe ferromagnetic ordering. Such increases are likely related to the increased\nfraction of Co$^{3+}$ in the high spin configuration, leading to the\nenhancement of Co$^{3+}$--O--Mn$^{4+}$ AFM phase and to the reduction in the\nuncompensation of the AFM coupling between Co and Mn. The combined effect of\nthe increased $\\mu_{eff}$ and AFM phase plausible explains the changes in the\nSEB effect."
    },
    {
        "anchor": "Ab initio investigation of light-induced relativistic spin-flip effects\n  in magneto-optics: Excitation of a metallic ferromagnet such as Ni with an intensive femtosecond\nlaser pulse causes an ultrafast demagnetization within approximately 300 fs. It\nwas proposed that the ultrafast demagnetization measured in femtosecond\nmagneto-optical experiments could be due to relativistic light-induced\nprocesses. We perform an ab initio investigation of the influence of\nrelativistic effects on the magneto-optical response of Ni. To this end, we\ndevelop, first, a response theory formulation of the additional appearing\nultra-relativistic terms in the Foldy-Wouthuysen transformed Dirac Hamiltonian\ndue to the electromagnetic field, and, second, compute the influence of\nrelativistic light-induced spin-flip transitions on the magneto-optics. Our ab\ninitio calculations of relativistic spin-flip optical excitations predict that\nthese can give only a very small contribution ($\\leq 0.1$%) to the\nlaser-induced magnetization change in Ni.",
        "positive": "Ferroelectric Soft Mode in Pb(Mg1/3Nb2/3)O3: Ferroelectric soft mode in Pb(Mg1/3Nb2/3)O3 (PMN) has been clearly resolved\nby precision Raman scattering measurements for the first time. A polarization\ndirection of the incident laser was chosen along [110] in cubic configuration\nin order to eliminate strong scattering components around 45 cm-1, which always\nsmeared the low-frequency spectra of PMN. The soft mode frequency omega_s\n(=\\sqrt{omega_0^2-gamma^2}) softens around 200 K, where omega_0 and gamma are a\nharmonic frequency and a damping constant, respectively. The present result\nevidenced that the origin of the polarizationthe in PMN is the soft mode."
    },
    {
        "anchor": "Unified ab initio description of Fr\u00f6hlich electron-phonon interactions\n  in two-dimensional and three-dimensional materials: \\textit{Ab initio} calculations of electron-phonon interactions including the\npolar Fr\\\"ohlich coupling have advanced considerably in recent years. The\nFr\\\"ohlich electron-phonon matrix element is by now well understood in the case\nof bulk three-dimensional (3D) materials. In the case of two-dimensional (2D)\nmaterials, the standard procedure to include Fr\\\"ohlich coupling is to employ\nCoulomb truncation, so as to eliminate artificial interactions between periodic\nimages of the 2D layer. While these techniques are well established, the\ntransition of the Fr\\\"ohlich coupling from three to two dimensions has not been\ninvestigated. Furthermore, it remains unclear what error one makes when\ndescribing 2D systems using the standard bulk formalism in a periodic supercell\ngeometry. Here, we generalize previous work on the \\textit{ab initio}\nFr\\\"ohlich electron-phonon matrix element in bulk materials by investigating\nthe electrostatic potential of atomic dipoles in a periodic supercell\nconsisting of a 2D material and a continuum dielectric slab. We obtain a\nunified expression for the matrix element, which reduces to the existing\nformulas for 3D and 2D systems when the interlayer separation tends to zero or\ninfinity, respectively. This new expression enables an accurate description of\nthe Fr\\\"ohlich matrix element in 2D systems without resorting to Coulomb\ntruncation. We validate our approach by direct \\textit{ab initio}\ndensity-functional perturbation theory calculations for monolayer BN and\nMoS$_2$, and we provide a simple expression for the 2D Fr\\\"ohlich matrix\nelement that can be used in model Hamiltonian approaches. The formalism\noutlined in this work may find applications in calculations of polarons,\nquasiparticle renormalization, transport coefficients, and superconductivity,\nin 2D and quasi-2D materials.",
        "positive": "CVM studies on the atomic ordering in complex perovskite alloys: The atomic ordering in complex perovskite alloys is investigated by the\ncluster variation method (CVM). For the 1/3\\{111\\}-type ordered structure, the\norder-disorder phase transition is the first order, and the order parameter of\nthe 1:2 complex perovskite reaches its maximum near x=0.25. For the\n1/2\\{111\\}-type ordered structure, the ordering transition is the second order.\nPhase diagrams for both ordered structures are obtained. The order-disorder\nline obeys the linear law."
    },
    {
        "anchor": "On the role of Calcium in inducing superconductivity - the study of\n  La-2125 superconductors: Ever since high Tc superconductivity was discovered in La-based mixed oxide\nsystem by Bednorz and Muller, enormous efforts have been put in by several\nresearchers around the world in understanding the origin and mechanism of\nsuperconductivity in these, as well as in systems derived from them. It is a\nproven fact that the superconductivity in RE-123 superconductors is governed by\nthe oxygen content, which in turn is responsible for the carrier concentration\nin the system. Due to their dependence on oxygen content, RE-123\nsuperconductors undergo structural transformation from orthorhombic to\ntetragonal as a function of oxygen content making them very difficult compounds\nto work with, in terms of technological applications, such as device\nfabrication. Hence, it would be interesting to obtain a stable compound whose\nsuperconducting properties, are not only insensitive directly to oxygen content\nbut, having dependence of its carrier concentration and Tc on the nature and\namount of the substituted cation. In the present work, we focus our\ninvestigations for such a compound, which has been derived from a tetragonal\nRE-123 superconducting system.\n  In this chapter, we present a brief review of the studies carried out on\nLa-2125 compounds to elucidate the role of dopants in modifying the\nsuperconducting properties and establish a structure-property correlation in\nthem.",
        "positive": "Water-based and Biocompatible 2D Crystal Inks: from Ink Formulation to\n  All- Inkjet Printed Heterostructures: Fully exploiting the properties of 2D crystals requires a mass production\nmethod able to produce heterostructures of arbitrary complexity on any\nsubstrate, including plastic. Solution processing of graphene allows simple and\nlow-cost techniques such as inkjet printing to be used for device fabrication.\nHowever, available inkjet printable formulations are still far from ideal as\nthey are either based on toxic solvents, have low concentration, or require\ntime-consuming and expensive formulation processing. In addition, none of those\nformulations are suitable for thin-film heterostructure fabrication due to the\nre-mixing of different 2D crystals, giving rise to uncontrolled interfaces,\nwhich results in poor device performance and lack of reproducibility. In this\nwork we show a general formulation engineering approach to achieve highly\nconcentrated, and inkjet printable water-based 2D crystal formulations, which\nalso provides optimal film formation for multi-stack fabrication. We show\nexamples of all-inkjet printed heterostructures, such as large area arrays of\nphotosensors on plastic and paper and programmable logic memory devices, fully\nexploiting the design flexibility of inkjet printing. Finally, dose-escalation\ncytotoxicity assays in vitro also confirm the inks biocompatible character,\nrevealing the possibility of extending use of such 2D crystal formulations to\ndrug delivery and biomedical applications."
    },
    {
        "anchor": "An original way for producing a 2.5 GPa strength ductile steel by\n  rolling of martensite: A compositionally-graded steel composed of martensite with 0.4%C on the\ncentre and bainite with 0.1%C on the surface was manufactured by partial\ndecarburization. It is reported that the as quenched material can be cold\nrolled up to an equivalent strain of 1.5 without cracks. The mechanical\nproperties of the cold-rolled material exhibits up to 2.5 GPa strength and\nductility. A simple mechanical model is developed to predict the stress state\nafter rolling of the graded structure explaining the good ductility of the\npresent high strength materials.",
        "positive": "Weyl-loop half metal in Li$_3$(FeO$_3$)$_2$: Nodal-line metals and semimetals, as interesting topological states of\nmatter, have been mostly studied in nonmagnetic materials. Here, based on\nfirst-principles calculations and symmetry analysis, we predict that fully\nspin-polarized Weyl loops can be realized in the half metal state for the\nthree-dimensional material Li$_3$(FeO$_3$)$_2$. We show that this material has\na ferromagnetic ground state, and it is a half metal with only a single spin\nchannel present near the Fermi level. The spin-up bands form two separate Weyl\nloops close to the Fermi level, which arise from band inversions and are\nprotected by the glide mirror symmetry. One loop is of type-I, whereas the\nother loop is of hybrid type. Corresponding to these two loops in the bulk, on\nthe (100) surface, there exist two fully spin-polarized drumheads of surface\nstates within the surface projections of the loops. The effects of the electron\ncorrelation and the spin-orbit coupling, as well as the possible hourglass Weyl\nchains in the nonmagnetic state have been discussed. The realization of fully\nspin-polarized Weyl-loop fermions in the bulk and drumhead fermions on the\nsurface for a half metal may generate promising applications in spintronics."
    },
    {
        "anchor": "Early steps in the formation of the interface between organic molecular\n  semiconductors and metals: a computational approach: A computational approach for predictive simulations of the nanoscale\nmorphology in the early steps of the formation of the interface between metals\nand organic molecular semiconductors is presented. Despite the relevance of the\nmetal-molecule junction for the development of electronic applications,\nstructural details at the interface are often difficult to assess. Our\napproach, based on the integration of density functional theory with methods\nfor the simulation of growth dynamics, allows to unravel the structural details\nof the formation of gold aggregates onto molecular materials. Simulations are\napplied to investigations of the initial steps in the formation of gold\nclusters at the interface with prototypical p-type and n-type organic molecular\nsemiconductors. Results show a striking correlation between the morphology of\nthe metal-organic interface, the details of the molecular structure and the\npeculiar metal-molecule interaction, also highlighting the role of fabrication\nconditions.",
        "positive": "Esaki diodes in van der Waals heterojunctions with broken-gap energy\n  band alignment: Van der Waals (vdW) heterojunctions composed of 2-dimensional (2D) layered\nmaterials are emerging as a solid-state materials family that exhibit novel\nphysics phenomena that can power high performance electronic and photonic\napplications. Here, we present the first demonstration of an important building\nblock in vdW solids: room temperature (RT) Esaki tunnel diodes. The Esaki\ndiodes were realized in vdW heterostructures made of black phosphorus (BP) and\ntin diselenide (SnSe2), two layered semiconductors that possess a broken-gap\nenergy band offset. The presence of a thin insulating barrier between BP and\nSnSe2 enabled the observation of a prominent negative differential resistance\n(NDR) region in the forward-bias current-voltage characteristics, with a peak\nto valley ratio of 1.8 at 300 K and 2.8 at 80 K. A weak temperature dependence\nof the NDR indicates electron tunneling being the dominant transport mechanism,\nand a theoretical model shows excellent agreement with the experimental\nresults. Furthermore, the broken-gap band alignment is confirmed by the\njunction photoresponse and the phosphorus double planes in a single layer of BP\nare resolved in transmission electron microscopy (TEM) for the first time. Our\nresults represent a significant advance in the fundamental understanding of vdW\nheterojunctions, and widen the potential applications base of 2D layered\nmaterials."
    },
    {
        "anchor": "Defect Sizing, Separation and Substrate Effects in Ion-Irradiated\n  Monolayer 2D Materials: Precise and scalable defect engineering of 2D nanomaterials is acutely\nsought-after in contemporary materials science. Here we present defect\nengineering in monolayer graphene and molybdenum disulfide (MoS$_2$) by\nirradiation with noble gas ions at 30 keV. Two ion species of different masses\nwere used in a gas field ion source microscope: helium (He$^+$) and neon\n(Ne$^+$). A detailed study of the introduced defect sizes and resulting\ninter-defect distance with escalating ion dose was performed using Raman\nspectroscopy. Expanding on existing models, we found that the average defect\nsize is considerably smaller for supported than freestanding graphene and that\nthe rate of defect production is larger. We conclude that secondary atoms from\nthe substrate play a significant role in defect production, creating smaller\ndefects relative to those created by the primary ion beam. Furthermore, a\nsimilar model was also applied to supported MoS$_2$, another promising member\nof the 2D material family. Defect yields for both ions were obtained for\nMoS$_2$, demonstrating their different interaction with the material and\nfacilitating comparison with other irradiation conditions in the literature.",
        "positive": "High-Ampacity Power Cables of Tightly-Packed and Aligned Carbon\n  Nanotubes: We characterize the current-carrying capacity (CCC), or ampacity, of\nhighly-conductive, light, and strong carbon nanotube (CNT) fibers by measuring\ntheir failure current density (FCD) and continuous current rating (CCR) values.\nWe show, both experimentally and theoretically, that the CCC of these fibers is\ndetermined by the balance between current-induced Joule heating and heat\nexchange with the surroundings. The measured FCD values of the fibers range\nfrom 10$^7$ to 10$^9$ A/m$^2$ and are generally higher than the previously\nreported values for aligned buckypapers, carbon fibers, and CNT fibers. To our\nknowledge, this is the first time the CCR for a CNT fiber has been reported. We\ndemonstrate that the specific CCC (i.e., normalized by the linear mass density)\nof our CNT fibers are higher than those of copper."
    },
    {
        "anchor": "Spin Pumping in Electrodynamically Coupled Magnon-Photon Systems: We use electrical detection, in combination with microwave transmission, to\ninvestigate both resonant and non-resonant magnon-photon coupling at room\ntemperature. Spin pumping in a dynamically coupled magnon-photon system is\nfound to be distinctly different from previous experiments. Characteristic\ncoupling features such as modes anti-crossing, line width evolution, peculiar\nline shape, and resonance broadening are systematically measured and\nconsistently analyzed by a theoretical model set on the foundation of classical\nelectrodynamic coupling. Our experimental and theoretical approach pave the way\nfor pursuing microwave coherent manipulation of pure spin current via the\ncombination of spin pumping and magnon-photon coupling.",
        "positive": "Spin Susceptibility and Helical Magnetic Orders at the Edges/Surfaces of\n  Topological Insulators Due to Fermi Surface Nesting: We study spin susceptibility and magnetic order at the edges/surfaces of\ntwo-dimensional and three-dimensional topological insulators when the Fermi\nsurface is nested. We find that due to spin-momentum locking as well as\ntime-reversal symmetry, spin susceptibility at the nesting wavevector has a\nstrong {\\em helical} feature. It follows then, a {\\em helical} spin density\nwave (SDW) state emerges at low temperature due to Fermi surface nesting. The\nhelical feature of spin susceptibility also has profound impact on the magnetic\norder in magnetically doped surface of three dimensional topological\ninsulators. In such system, from the mean field Zener theory, we predict a {\\em\nhelical} magnetic order."
    },
    {
        "anchor": "Prediction of Giant Tunneling Magnetoresistance in\n  RuO$_{2}$/TiO$_{2}$/RuO$_{2}$ (110) Antiferromagnetic Tunnel Junctions: Using first-principles quantum-transport calculations, we investigate\nspin-dependent electronic and transport properties of antiferromagnetic tunnel\njunctions (AFMTJs) that consist of (110)-oriented antiferromagnetic (AFM) metal\nRuO$_{2}$ electrodes and an insulating TiO$_{2}$ tunneling barrier. We predict\nthe emergence of a giant tunneling magnetoresistance (TMR) effect in a wide\nenergy window, a series of barrier layer thicknesses, and different interface\nterminations, indicating the robustness of this effect. We show that the\npredicted TMR cannot be explained in terms of the global transport\nspin-polarization of RuO$_{2}$ (110) but is well understood based on matching\nthe momentum-dependent spin-polarized conduction channels of the two RuO$_{2}$\n(110) electrodes. We predict oscillations of TMR with increasing barrier\nthickness, indicating a non-negligible contribution from the perfectly\nepitaxial interfaces. Our work helps the understanding of the physics of TMR in\nAFMTJs and aids in realizing efficient AFM spintronic devices.",
        "positive": "Interaction effects and transport properties of Pt capped Co\n  nanoparticles: We studied the magnetic and transport properties of Co nanoparticles (NPs)\nbeing capped with varying amounts of Pt. Beside field and temperature dependent\nmagnetization measurements we performed delta-M measurements to study the\nmagnetic interactions between the Co NPs. We observe a transition from\ndemagnetizing towards magnetizing interactions between the particles for an\nincreasing amount of Pt capping. Resistivity measurements show a crossover from\ngiant magnetoresistance towards anisotropic magnetoresistance."
    },
    {
        "anchor": "Electric breakdown in ultra-thin MgO tunnel barrier junctions for\n  spin-transfer torque switching: Magnetic tunnel junctions for spin-transfer torque switching were prepared to\ninvestigate the dielectric breakdown. The breakdown occurs typically at\nvoltages not much higher than the switching voltages, a bottleneck for the\nimplementation of spin-transfer torque Magnetic Random Access Memory. Intact\nand broken tunnel junctions are characterized by transport measurements and\nthen prepared for transmission electron microscopy and energy dispersive x-ray\nspectrometry by focussed ion beam. The comparison to our previous model of the\nelectric breakdown for thicker MgO tunnel barriers reveals significant\ndifferences arising from the high current densities.",
        "positive": "The Phonon Quasiparticle Approach for Anharmonic Properties of Solids: Knowledge of lattice anharmonicity is essential to elucidate distinctive\nthermal properties in crystalline solids. Yet, accurate \\textit{ab initio}\ninvestigations of lattice anharmonicity encounter difficulties owing to the\ncumbersome computations. Here we introduce the phonon quasiparticle approach\nand review its application to various materials. This method efficiently and\nreliably addresses lattice anharmonicity by combining \\textit{ab initio}\nmolecular dynamics and lattice dynamics calculations. Thus, in principle, it\naccounts for full anharmonic effects and overcomes finite-size effects typical\nof \\textit{ab initio} molecular dynamics. The validity and effectiveness of the\ncurrent approach are demonstrated in the computation of thermodynamic and heat\ntransport properties of weakly and strongly anharmonic systems."
    },
    {
        "anchor": "An Accurate Method for Measuring Activation Energy: In this letter, we present an accurate method for the measurement of\nactivation energy. This method combined the excitation power dependent\nphotoluminescence and temperature dependent photoluminescence together to\nobtain activation energy. We found with increasing temperature, there is a step\ntransition from one emission mechanism to another. This step transition gives\nus an accurate measurement of activation energy. Using this new method we found\nthe activation energy of the free exciton A in a GaN thin film is 24 meV. Our\nresult also gives a reasonable explanation of the debate of the origin of the\nlight emission in GaN at room temperature.",
        "positive": "Interface modes of two-dimensional composite structures: The surface modes of a composite consisting of aligned metallic wires with\nsquare cross sections are investigated, on the basis of photonic band structure\ncalculations. The effective long-wavelength dielectric response function is\ncomputed, as a function of the filling fraction. The dependence of the optical\nabsorption on the shape of the wires and the polarization of light is\ndiscussed, and the effect of sharp corners analyzed. The effect of the\ninteraction between the wires on the localization of surface plasmons is also\naddressed."
    },
    {
        "anchor": "The structure and stability of beta-Ta thin films: Ta films with tetragonal crystalline structure (beta-phase), deposited by\nmagnetron sputtering on different substrates (steel, silicon and silicon\ndioxide), have been studied. In all cases, very highly preferred (001)\norientation was observed in x-ray diffraction (XRD) measurements. All\ndiffraction data revealed two weak reflections corresponding to d-spacing of\n0.5272 and 0.1777 nm. The presence of the two peaks, attributed to (001) and\n(003) reflections, indicates that beta-Ta films exhibit a high preference for\nthe space group of P-421m over P42/mnm, previously proposed for beta-Ta.\nDifferences in relative intensities of (00l) reflections, calculated for single\ncrystal beta-Ta sigma-type Frank-Kasper structure and those measured in the\nfilms, are attributed to defects in the films. Molecular dynamics simulations\nperformed on tantalum clusters with six different initial configurations using\nthe embedded-atom-method (EAM) potential revealed the stability of beta-Ta,\nwhich might explain its growth on many substrates under various deposition\nconditions.",
        "positive": "Pair vs many-body potentials: influence on elastic and plastic behavior\n  in nanoindentation: Molecular-dynamics simulation can give atomistic information on the processes\noccurring in nanoindentation experiments. In particular, the nucleation of\ndislocation loops, their growth, interaction and motion can be studied. We\ninvestigate how realistic the interatomic potentials underlying the simulations\nhave to be in order to describe these complex processes. Specifically we\ninvestigate nanoindentation into a Cu single crystal. We compare simulations\nbased on a realistic many-body interaction potential of the\nembedded-atom-method type with two simple pair potentials, a Lennard-Jones and\na Morse potential. We find that qualitatively many aspects of nanoindentation\nare fairly well reproduced by the simple pair potentials: elastic regime,\ncritical stress and indentation depth for yielding, dependence on the crystal\norientation, and even the level of the hardness. The quantitative deficits of\nthe pair potential predictions can be traced back (i) to the fact that the pair\npotentials are unable in principle to model the elastic anisotropy of cubic\ncrystals; (ii) as the major drawback of pair potentials we identify the gross\nunderestimation of the stable stacking fault energy. As a consequence these\npotentials predict the formation of too large dislocation loops, the too rapid\nexpansion of partials, too little cross slip and in consequence a severe\noverestimation of work hardening."
    },
    {
        "anchor": "A Novel Ferroelectric Rashba Semiconductor: Fast, reversible, and low-power manipulation of the spin texture is crucial\nfor next generation spintronic devices like non-volatile bipolar memories,\nswitchable spin current injectors or spin field effect transistors.\nFerroelectric Rashba semiconductors (FERSC) are the ideal class of materials\nfor the realization of such devices. Their ferroelectric character enables an\nelectronic control of the Rashba-type spin texture by means of the reversible\nand switchable polarization. Yet, only very few materials have been established\nto belong to this class of multifunctional materials. Here, Pb1-xGexTe is\nunraveled as a novel FERSC system down to nanoscale. The ferroelectric phase\ntransition and concomitant lattice distortion is demonstrated by temperature\ndependent X-ray diffraction, and its effect on electronic properties are\nmeasured by angle-resolved photoemission spectroscopy. In few nanometer-thick\nepitaxial heterostructures, a large Rashba spin-splitting is exhibiting a wide\ntuning range as a function of temperature and Ge content. Our work defines Pb1-\nxGexTe as a high-potential FERSC system for spintronic applications.",
        "positive": "Thickness-dependent electron momentum relaxation times in iron films: Terahertz time-domain conductivity measurements in 2 to 100 nm thick iron\nfilms resolve the femtosecond time delay between applied electric fields and\nresulting currents. This current response time decreases from 29 fs for\nthickest films to 7 fs for the thinnest films. The macroscopic response time is\nnot strictly proportional to the conductivity. This excludes the existence of a\nsingle relaxation time universal for all conduction electrons. We must assume a\ndistribution of microscopic momentum relaxation times. The macroscopic response\ntime depends on average and variation of this distribution; the observed\ndeviation between response time and conductivity scaling corresponds to the\nscaling of the variation. The variation of microscopic relaxation times depends\non film thickness because electrons with different relaxation times are\naffected differently by the confinement since they have different mean free\npaths."
    },
    {
        "anchor": "Merging of the grains during wire drawing: It has been first proved the effect of grains merging during drawing\ndeformation. This was done with example of producing a steel wire from rod\nmanufactured by rolling with shear technology and was shown not only grain\nrefinement but its merging as well. The result obtained in current work has\nfundamental importance; it reveals new mechanism of the \"recrystallization\"\nwhich takes place without diffusion actions owing to the mechanical impact.",
        "positive": "Little helpers for your experiment - NOBUGS2002/013: The World Wide Web (WWW) is a wonderful tool to provide users with\ndocumentation and tools that make the preparation and running of an experiment\na little easier. We present a set of tools that allow one to estimate the\nactivation of a sample in the neutron beam, or to calculate the absorption of a\nsample. Ever tried to figure out the time for the next sample change - here our\nscheduler can help. In addition there is a simple database that can be used to\nkeep track of all the data files collected at various facilities. We present\nthese little tools, but also demonstrate how easy it is to create new WWW based\ntools that make the life of users easier."
    },
    {
        "anchor": "Inter- and intra-layer excitons in MoS$_2$/WS$_2$ and MoSe$_2$/WSe$_2$\n  heterobilayers: Accurately described excitonic properties of transition metal dichalcogenide\nheterobilayers (HBLs) are crucial to comprehend the optical response and the\ncharge carrier dynamics of them. Excitons in multilayer systems posses inter or\nintralayer character whose spectral positions depend on their binding energy\nand the band alignment of the constituent single-layers. In this study, we\nreport the electronic structure and the absorption spectra of MoS$_2$/WS$_2$\nand MoSe$_2$/WSe$_2$ HBLs from first-principles calculations. We explore the\nspectral positions, binding energies and the origins of inter and intralayer\nexcitons and compare our results with experimental observations. The absorption\nspectra of the systems are obtained by solving the Bethe-Salpeter equation on\ntop of a G$_0$W$_0$ calculation which corrects the independent particle\neigenvalues obtained from density functional theory calculations. Our\ncalculations reveal that the lowest energy exciton in both HBLs possesses\ninterlayer character which is decisive regarding their possible device\napplications. Due to the spatially separated nature of the charge carriers, the\nbinding energy of inter-layer excitons might be expected to be considerably\nsmaller than that of intra-layer ones. However, according to our calculations\nthe binding energy of lowest energy interlayer excitons is only $\\sim$ 20\\%\nlower due to the weaker screening of the Coulomb interaction between layers of\nthe HBLs. Therefore, it can be deduced that the spectral positions of the\ninterlayer excitons with respect to intralayer ones are mostly determined by\nthe band offset of the constituent single-layers. By comparing oscillator\nstrengths and thermal occupation factors, we show that in luminescence at low\ntemperature, the interlayer exciton peak becomes dominant, while in absorption\nit is almost invisible.",
        "positive": "Anomalous coercivity enhancement with temperature and tunable exchange\n  bias in Gd and Ti co-doped BiFeO$_3$ multiferroics: We have investigated the effect of temperature on magnetic properties of\nBi$_{0.9}$Gd$_{0.1}$Fe$_{1-x}$Ti$_x$O$_3$ (x = 0.00-0.20) multiferroic system.\nUnexpectedly, the coercive fields ($H_{c}$) of this multiferroic system\nincreased with increasing temperature. The coercive fields and remanent\nmagnetization were higher over a wide range of temperatures in sample x = 0.10\ni.e. in sample having composition Bi$_{0.9}$Gd$_{0.1}$Fe$_{0.9}$Ti$_{0.1}$O$_3$\nthan those of x = 0.00 and 0.20 compositions. Therefore, we have carried out\ntemperature dependent magnetization experiments extensively for sample x =\n0.10. The magnetic hysteresis loops at different temperatures exhibit an\nasymmetric shift towards the magnetic field axes which indicate the presence of\nexchange bias effect in this material system. The hysteresis loops were also\ncarried out at temperatures 150 K and 250 K by cooling down the sample from 300\nK in various cooling magnetic fields ($H_{cool}$). The exchange bias field\n($H_{EB}$) values increased with $H_{cool}$ and decreased with temperature. The\n$H_{EB}$ values were tunable by field cooling at temperatures up to 250 K."
    },
    {
        "anchor": "$g-B_{3}C_{2}N_{3}$: A new potential two dimensional metal-free\n  photocatalyst for overall water splitting: In this work, using a hybrid density functional theory (DFT) based\ncalculation, we propose a new two-dimensional (2D) B-C-N material,\n$g-B_{3}C_{2}N_{3}$, with the promising prospect of metal-free photocatalysis.\nA comprehensive investigation demonstrates that it is a near ultraviolet (UV)\nabsorbing direct band gap (3.69 eV) semiconductor with robust dynamical and\nmechanical stability. Estimating the band positions with respect to water\noxidation and hydrogen reduction potential levels, we observe that\n$g-B_{3}C_{2}N_{3}$ monolayer shows the possibility to be used for hydrogen\nfuel generation through spontaneous solar water splitting, over a broad pH\nrange. Upon biaxial strain application the band gap decreases with increase in\ntensile strain, leading to a subsequent red shift in absorption spectra,\nimplying enhanced photon harvest under solar irradiation. Furthermore, due to a\ncombined effect of band gap and work function variation, biaxial strain\nrealigns the band positions, allowing one to control the reducing or oxidizing\nability as per requirement to attain environmental sustainability.",
        "positive": "A New View on Geometry Optimization: the Quasi-Independent Curvilinear\n  Coordinate Approximation: This article presents a new and efficient alternative to well established\nalgorithms for molecular geometry optimization. The new approach exploits the\napproximate decoupling of molecular energetics in a curvilinear internal\ncoordinate system, allowing separation of the 3N-dimensional optimization\nproblem into an O(N) set of quasi-independent one-dimensional problems. Each\nuncoupled optimization is developed by a weighted least squares fit of energy\ngradients in the internal coordinate system followed by extrapolation. In\nconstruction of the weights, only an implicit dependence on topologically\nconnected internal coordinates is present. This new approach is competitive\nwith the best internal coordinate geometry optimization algorithms in the\nliterature and works well for large biological problems with complicated\nhydrogen bond networks and ligand binding motifs."
    },
    {
        "anchor": "Embedding methods for large-scale surface calculations: One of the goals in the development of large scale electronic structure\nmethods is to perform calculations explicitly for a localised region of a\nsystem, while still taking into account the rest of the system outside of this\nregion. An example of this in surface physics would be to embed an adsorbate\nand a few surface atoms into an extended substrate, hence considerably reducing\ncomputational costs. Here we apply the constrained electron density method of\nembedding a Kohn-Sham system in a substrate system (first described by P.\nCortona\\cite{1} and T.A. Wesolowski\\cite{2}), within a plane-wave basis and\npseudopotential framework. This approach divides the charge density of the\nsystem into substrate and embedded charge densities, the sum of which is the\ncharge density of the actual system of interest. Two test cases are considered.\nFirst we construct fcc bulk aluminium by embedding one cubic lattice of atoms\nwithin another. Second, we examine a model surface/adsorbate system of\naluminium on aluminium and compare with full Kohn-Sham results.",
        "positive": "Quantitative Analysis of Experimental and Synthetic Microstructures for\n  Sedimentary Rock: A quantitative comparison between the experimental microstructure of a\nsedimentary rock and three theoretical models for the same rock is presented.\nThe microstructure of the rock sample (Fontainebleau sandstone) was obtained by\nmicrotomography. Two of the models are stochastic models based on correlation\nfunction reconstruction, and one model is based on sedimentation, compaction\nand diagenesis combined with input from petrographic analysis. The porosity of\nall models closely match that of the experimental sample and two models have\nalso the same two point correlation function as the experimental sample. We\ncompute quantitative differences and similarities between the various\nmicrostructures by a method based on local porosity theory. Differences are\nfound in the degree of anisotropy, and in fluctuations of porosity and\nconnectivity. The stochastic models differ strongly from the real sandstone in\ntheir connectivity properties, and hence need further refinement when used to\nmodel transport."
    },
    {
        "anchor": "Coherent dynamics and mapping of excitons in single-layer MoSe$_2$ and\n  WSe$_2$ at the homogeneous limit: We perform coherent nonlinear spectroscopy of excitons in single-layers of\nMoSe$_2$ and WSe$_2$ encapsulated between thin films of hexagonal boron\nnitride. Employing four-wave mixing microscopy we identify virtually disorder\nfree areas, generating exciton optical response at the homogeneous limit.\nFocussing on such areas, we measure exciton homogeneous broadening as a\nfunction of environmental factors, namely temperature and exciton density.\nExploiting FWM imaging, we find that at such locations, nonlinear absorption of\nthe exciton excited states and their coherent couplings can be observed. Using\nthe WSe$_2$ heterostructure, we infer coherence and density dynamics of the\nexciton 2S state. Owing to its increased radiative lifetime, at low\ntemperatures, the dephasing of the 2S state is longer than of the 1S\ntransition. While scanning various heterostructures across tens of micrometers,\nwe conclude that the disorder, principally induced by strain variations, remain\nto be present creating spatially varying inhomogeneous broadening.",
        "positive": "Perpendicular magnetic anisotropy in insulating ferrimagnetic gadolinium\n  iron garnet thin films: We present experimental control of the magnetic anisotropy in a gadolinium\niron garnet (GdIG) thin film from in-plane to perpendicular anisotropy by\nsimply changing the sample temperature. The magnetic hysteresis loops obtained\nby SQUID magnetometry measurements unambiguously reveal a change of the\nmagnetically easy axis from out-of-plane to in-plane depending on the sample\ntemperature. Additionally, we confirm these findings by the use of temperature\ndependent broadband ferromagnetic resonance spectroscopy (FMR). In order to\ndetermine the effective magnetization, we utilize the intrinsic advantage of\nFMR spectroscopy which allows to determine the magnetic anisotropy independent\nof the paramagnetic substrate, while magnetometry determines the combined\nmagnetic moment from film and substrate. This enables us to quantitatively\nevaluate the anisotropy and the smooth transition from in-plane to\nperpendicular magnetic anisotropy. Furthermore, we derive the temperature\ndependent $g$-factor and the Gilbert damping of the GdIG thin film."
    },
    {
        "anchor": "Magnetoresistance and robust resistivity plateau in MoAs2: We have grown the MoAs$_2$ single crystal which crystallizes in a monoclinic\nstructure with C2/m space group. Transport measurements show that MoAs$_2$\ndisplays a metallic behavior at zero field and undergoes a\nmetal-to-semiconductor crossover at low temperatures when the applied magnetic\nfield is over 5 T. A robust resistivity plateau appears below 18 K and persists\nfor the field up to 9 T. A large positive magnetoresistance (MR), reaching\nabout 2600\\% at 2 K and 9 T, is observed when the field is perpendicular to the\ncurrent.The MR becomes negative below 40 K when the field is rotated to be\nparallel to the current. The Hall resistivity shows the non-linear\nfield-dependence below 70 K. The analysis using two-band model indicates a\ncompensated electron-hole carrier density at low temperatures. A combination of\nthe breakdown of Kohler's rule, the abnormal drop and the cross point in Hall\ndata implies that a possible Lifshitz transition has occurred between 30 K and\n60 K, likely driving the compensated electron-hole density, the large MR as\nwell as the metal-semiconductor transition in MoAs$_2$. Our results indicate\nthat the family of centrosymmetric transition-metal dipnictides has rich\ntransport behavior which can in general exhibit variable metallic and\ntopological features.",
        "positive": "Photoluminescence study of V-groove quantum wires: The influence of\n  disorder on the optical spectra and the carrier thermalization: We report on time-resolved and steady-state photoluminescence studies of\nGaAs/AlGaAs V-groove quantum wire structures. Steady-state photoluminescence\nexperiments are performed in the temperature range from 8K to 200K. We evaluate\nthe relation between photoluminescence excitation and absorption and determine\nexperimentally an optical density in order to analyze the temperature\ndependence of the photoluminescence spectra. We find that, at a temperature\nabove 60K, the photoexcited electron-hole pairs reach a thermal equilibrium at\nthe lattice temperature while, at a temperature below about 60K, they do not\nreach a quasi-equilibrium in the steady-state. Time-resolved photoluminescence\nstudies performed at a carrier density of about 2. 104 cm-1 indicate that, at\n60K, a quasi-equilibrium is reached on a time scale of 10 ps. Furthermore, the\nhot carriers cool in about 100 ps to the lattice temperature. At 8K, however,\nevidence of a non-thermal carrier distribution is found at the earliest times,\nwhich suggests that carriers in extended states are not in thermal equilibrium\nwith carriers in localized states."
    },
    {
        "anchor": "Candidate structure for the H$_2$-PRE phase of solid hydrogen: Experimental progress finally reached the metallic solid hydrogen phase,\nwhich was predicted by Wigner and Huntington over 80 years ago. However, the\ndifferent structures in the phase diagram are still been debated due to the\ndifficulty of diffraction experiments for high-pressured hydrogen. The\ndetermination of crystal structures under extreme condition is both of the\nbasic condensed matter physics, and in planetary science: the behavior of giant\ngaseous planets (e.g. Jupiter, Saturn...) strongly depends on the properties of\ninner high-pressured hydrogen. This work describes new possible structures\nappearing under high pressures of 400$\\sim$600 GPa. We applied a structural\nsearch using particle swarm optimization with density functional theory (DFT)\nto propose several candidate structures. For these structures, we performed\nfixed-node diffusion Monte Carlo simulations combined with DFT zero-point\nenergy corrections to confirm their relative stability. We found $P2_{1}/c$-8\nas a promising candidate structure for the H$_2$-PRE phase. $P2_{1}/c$-8 is\npredicted the most stable at 400 and 500~GPa. $P2_{1}/c$-8 reproduces\nqualitatively the IR spectrum peaks observed in the H$_2$-PRE phase.",
        "positive": "Synthesis, processing and transport properties of cubic and trigonal\n  solid solutions in the Mg-Si-Sn system: Mg-Si-Sn solid solutions have interesting and useful semiconducting\nproperties particularly for thermoelectric applications. While cubic solid\nsolutions have been prepared by a variety of methods, solid solutions with a\ntrigonal crystal structure have not been reported. We employed a combination of\nhigh energy ball milling and current activated pressure assisted densification\n(CAPAD) to induce and complete phase transformation from cubic to trigonal\nphase, forming dense trigonal composites. This is the first successful\npreparation of the trigonal phase in Mg-Si-Sn stem. In addition, we report the\ntransport properties of both the cubic and trigonal composites measured in the\n160 to 400 K range. The electrical conductivity of the trigonal composites was\nseveral times higher compared to the cubic counterparts while thermal\nconductivity is lower but in the range of previously reported Mg-Si-Sn\nmaterials. The Seebeck coefficient of the trigonal composites is lower compared\nto the cubic samples, leading to low ZT values. The ZT of the cubic samples,\nhowever is higher than previously reported for un-doped Mg-Si-Sn solid\nsolutions which is promising for thermoelectric applications."
    },
    {
        "anchor": "Quantum radiations from exciton condensate in Electron-Hole Bilayer\n  Systems: Superfluid has been realized in Helium-4, Helium-3 and ultra-cold atoms. It\nhas been widely used in making high-precision devices and also in cooling\nvarious systems. There have been extensive experimental search for possible\nexciton superfluid (ESF) in semiconductor electron-hole bilayer (EHBL) systems\nbelow liquid Helium temperature. However, exciton superfluid are meta-stable\nand will eventually decay through emitting photons. Here we study quantum\nnature of photons emitted from the excitonic superfluid (ESF) phase in the\nsemiconductor EHBL and find that the light emitted from the excitonic\nsuperfluid has unique and unusual features not shared by any other atomic or\ncondensed matter systems. We show that the emitted photons along the direction\nperpendicular to the layer are in a coherent state, those along all tilted\ndirections are in a two modes squeezed state. We determine the two mode\nsqueezing spectra, the angle resolved power spectrum, the line shapes of both\nthe momentum distribution curve (MDC) and the energy distribution curve (EDC).\n  From the two photon correlation functions, we find there are photon bunching,\nthe photo-count statistics is super-Poissonian. We discuss how several\nimportant parameters such as the chemical potential, the exciton decay rate,\nthe quasiparticle energy spectrum and the dipole-dipole interaction strength\nbetween the excitons in our theory can be extracted from the experimental data\nand comment on available experimental data on both EDC and MDC.",
        "positive": "Tunable Magnetic Anisotropy in Patterned SrRuO3 Quantum Structures:\n  Competition between Lattice Anisotropy and Oxygen Octahedral Rotation: Artificial perovskite-oxide nanostructures possess intriguing magnetic\nproperties due to their tailorable electron-electron interactions, which are\nextremely sensitive to the oxygen coordination environment. To date,\nperovskite-oxide nanodots with sizes below 50 nm have rarely been reported.\nFurthermore, the oxygen octahedral distortion and its relation to magnetic\nproperties in perovskite oxide nanodots remain unexplored yet. Here, we have\nstudied the magnetic anisotropy in patterned SrRuO3 (SRO) nanodots as small as\n30 nm while performing atomic-resolution electron microscopy and spectroscopy\nto directly visualize the constituent elements, in particular oxygen ions. We\nobserve that the magnetic anisotropy and RuO6 octahedra distortion in SRO\nnanodots are both nanodots' size-dependent but remain unchanged in the first\n3-unit-cell interfacial SRO monolayers regardless of the dots' size. Combined\nwith the first principle calculations, we unravel a unique structural mechanism\nbehind the nanodots' size-dependent magnetic anisotropy in SRO nanodots,\nsugguesting that the competition between lattice anisotropy and oxygen\noctahedral rotation mediates anisotropic exchange interactions in SRO nanodots.\nThese findings demonstrate a new avenue towards tuning magnetic properties of\ncorrelated perovskite oxides and imply that patterned nanodots could be a\npromising playground for engineering emergent functional behaviors."
    },
    {
        "anchor": "Clean Os(0001) electronic surface states: a first-principle fully\n  relativistic investigation: We analyze the electronic structure of the Os(0001) surface by means of\nfirst-principle calculations based on Fully Relativistic (FR) Density\nFunctional Theory (DFT) and a Projector Augmented-Wave (PAW) approach. We\ninvestigate surface states and resonances analyzing their spin-orbit induced\nenergy splitting and their spin polarization. The results are compared with\npreviously studied surfaces Ir(111), Pt(111), and Au(111). We do not find any\nsurface state in the gap similar to the L-gap of the (111) fcc surfaces, but\nfind Rashba split resonances that cross the Fermi level and, as in the recently\nstudied Ir(111) surface, have a characteristic downward dispersion. Moreover,\nfor some selected surface states we study the spin polarization with respect to\n${\\bf k}_{\\parallel}$, the wave-vector parallel to the surface. In some cases,\nsuch as the Rashba split resonances, the spin polarization shows a smooth\nbehavior with slow rotations, in others the rotation is faster, due to mixing\nand anti-crossing of the states.",
        "positive": "A case study of multi-modal, multi-institutional data management for the\n  combinatorial materials science community: Although the convergence of high-performance computing, automation, and\nmachine learning has significantly altered the materials design timeline,\ntransformative advances in functional materials and acceleration of their\ndesign will require addressing the deficiencies that currently exist in\nmaterials informatics, particularly a lack of standardized experimental data\nmanagement. The challenges associated with experimental data management are\nespecially true for combinatorial materials science, where advancements in\nautomation of experimental workflows have produced datasets that are often too\nlarge and too complex for human reasoning. The data management challenge is\nfurther compounded by the multi-modal and multi-institutional nature of these\ndatasets, as they tend to be distributed across multiple institutions and can\nvary substantially in format, size, and content. To adequately map a materials\ndesign space from such datasets, an ideal materials data infrastructure would\ncontain data and metadata describing i) synthesis and processing conditions,\nii) characterization results, and iii) property and performance measurements.\nHere, we present a case study for the low-barrier development of such a\ndashboard that enables standardized organization, analysis, and visualization\nof a large data lake consisting of combinatorial datasets of synthesis and\nprocessing conditions, X-ray diffraction patterns, and materials property\nmeasurements generated at several different institutions. While this dashboard\nwas developed specifically for data-driven thermoelectric materials discovery,\nwe envision the adaptation of this prototype to other materials applications,\nand, more ambitiously, future integration into an all-encompassing materials\ndata management infrastructure."
    },
    {
        "anchor": "Observation of Ultralong Valley Lifetime in WSe2/MoS2 Heterostructures: The valley degree of freedom in two-dimensional (2D) crystals recently\nemerged as a novel information carrier in addition to spin and charge. The\nintrinsic valley lifetime in 2D transition metal dichalcoginides (TMD) is\nexpected to be remarkably long due to the unique spin-valley locking behavior,\nwhere the inter-valley scattering of electron requires simultaneously a large\nmomentum transfer to the opposite valley and a flip of the electron spin. The\nexperimentally observed valley lifetime in 2D TMDs, however, has been limited\nto tens of nanoseconds so far. Here we report efficient generation of\nmicrosecond-long lived valley polarization in WSe2/MoS2 heterostructures by\nexploiting the ultrafast charge transfer processes in the heterostructure that\nefficiently creates resident holes in the WSe2 layer. These valley-polarized\nholes exhibit near unity valley polarization and ultralong valley lifetime: we\nobserve a valley-polarized hole population lifetime of over 1 us, and a valley\ndepolarization lifetime (i.e. inter-valley scattering lifetime) over 40 us at\n10 Kelvin. The near-perfect generation of valley-polarized holes in TMD\nheterostructures with ultralong valley lifetime, orders of magnitude longer\nthan previous results, opens up new opportunities for novel valleytronics and\nspintronics applications.",
        "positive": "Magnetron Sputtered Non-Toxic and Precious Element-Free Ti-Zr-Ge\n  Metallic Glass Nanofilms with Enhanced Biocorrosion Resistance: The chemical composition and structural state of advanced alloys are the\ndecisive factors in optimum biomedical performance. This contribution presents\nunique Ti-Zr-Ge metallic glass thin-film compositions fabricated by magnetron\nsputter deposition targeted for nanocoatings for biofouling prevention. The\namorphous nanofilms with nanoscale roughness exhibit a large relaxation and\nsupercooled liquid regions as revealed by flash differential scanning\ncalorimetry. Ti\\textsubscript{68}Zr\\textsubscript{8}Ge\\textsubscript{24} shows\nthe lowest corrosion (0.17 \\textmu A cm\\textsuperscript{\\textminus2}) and\npassivation (1.22 \\textmu A cm\\textsuperscript{\\textminus2}) current densities,\nwith the lowest corrosion potential of \\textminus0.648 V and long-range\nstability against pitting, corroborating its excellent performance in phosphate\nbuffer solution at 37 {\\textdegree}C. The oxide layer is comprised of\nTiO\\textsubscript{2}, TiO\\textsubscript{\\emph{x}} and\nZrO\\textsubscript{\\emph{x}}, as determined using X-ray photoelectron\nspectroscopy by short-term ion-etching of the surface layer. The two orders of\nmagnitude increase in the oxide and interface resistance (from 14 to 1257\n{\\textOmega} cm\\textsuperscript{2}) along with an order of magnitude decrease\nin the capacitance parameter of the oxide interface (from 1.402 x\n10\\textsuperscript{\\textminus5} to 1.677 x 10\\textsuperscript{\\textminus6} S\ns\\textsuperscript{n} cm\\textsuperscript{\\textminus2}) of the same composition\nis linked to the formation of carbonyl groups and reduction of the native oxide\nlayer during linear sweep voltammetry."
    },
    {
        "anchor": "Systematic investigation of THz-induced excitonic Rabi splitting: Weak near-infrared and strong terahertz excitation are applied to study\nexcitonic Rabi splitting in (GaIn)As/GaAs quantum wells. Pronounced\nanticrossing behavior of the split peaks is observed for different terahertz\nintensities and detunings relative to the intraexcitonic heavy-hole\n1s-2p-transition. At intermediate to high electric fields the splitting becomes\nhighly asymmetric and exhibits significant broadening. A fully microscopic\ntheory is needed to explain the experimental results. Comparisons with a\ntwo-level model reveal the increasing importance of higher excitonic states at\nelevated excitation levels.",
        "positive": "Spin Mapping of Surface and Bulk Rashba States in Ferroelectric\n  a-GeTe(111) Films: A comprehensive mapping of the spin polarization of the electronic bands in\nferroelectric a-GeTe(111) films has been performed using a time-of-flight\nmomentum microscope equipped with an imaging spin filter that enables a\nsimultaneous measurement of more than 10.000 data points (voxels). A Rashba\ntype splitting of both surface and bulk bands with opposite spin helicity of\nthe inner and outer Rashba bands is found revealing a complex spin texture at\nthe Fermi energy. The switchable inner electric field of GeTe implies new\nfunctionalities for spintronic devices."
    },
    {
        "anchor": "Giant enhancement of cryogenic thermopower by polar structural\n  instability in the pressurized semimetal MoTe2: We found that a high mobility semimetal 1T'-MoTe2 shows a significant\npressure-dependent change in the cryogenic thermopower in the vicinity of the\ncritical pressure, where the polar structural transition disappears. With the\napplication of a high pressure of 0.75 GPa, while the resistivity becomes as\nlow as 10 {\\mu}{\\Omega}cm, thermopower reached the maximum value of 60\n{\\mu}VK-1 at 25 K, leading to a giant thermoelectric power factor of 300\n{\\mu}WK-2cm-1. Based on semiquantitative analyses, the origin of this behavior\nis discussed in terms of inelastic electron-phonon scattering enhanced by the\nsoftening of zone center phonon modes associated with the polar structural\ninstability.",
        "positive": "A Harris-type van der Waals density functional scheme: Large biomolecular systems, whose function may involve thousands of atoms,\ncannot easily be addressed with parameter-free density functional theory (DFT)\ncalculations. Until recently a central problem was that such systems possess an\ninherent sparseness, that is, they are formed from components that are mutually\nseparated by low-electron-density regions where dispersive forces contribute\nsignificantly to the cohesion and behavior. The introduction of, for example,\nthe van der Waals density functional (vdW-DF) method [PRL 92, 246401 (2004)]\nhas addressed part of this sparse-matter system challenge. However, while a\nvdW-DF study is often as computationally efficient as a study performed in the\ngeneralized gradient approximation, the scope of large-sparse-matter DFT is\nstill limited by computer time and memory. It is costly to self-consistently\ndetermine the electron wavefunctions and hence the kinetic-energy repulsion. In\nthis paper we propose and evaluate an adaption of the Harris scheme [PRB 31,\n1770 (1985)]. This is done to speed up non-selfconsistent vdW-DF studies of\nmolecular-system interaction energies. Also, the Harris-type analysis\nestablishes a formal link between dispersion-interaction effects on the\neffective potential for electron dynamics and the impact of including\nselfconsistency in vdW-DF calculations [PRB 76, 125112 (2007)]."
    },
    {
        "anchor": "Ab initio study of lattice dynamics of group IV semiconductors using\n  pseudohybrid functionals for extended Hubbard interactions: We study the lattice dynamics of group IV semiconductors using fully\nab-initio extended Hubbard functional. The onsite and intersite Hubbard\ninteractions are determined self-consistently with recently developed\npseudohybrid functionals and included in force calculations. We analyze the\nPulay forces by the choice of atomic orbital projectors and the force\ncontribution of the onsite and intersite Hubbard terms. The phonon dispersions,\nGr\u007funeisen parameters, and lattice thermal conductivities of diamond, silicon,\nand germanium, which are most-representative covalent-bonding semiconductors,\nare calculated and compared with the results using local, semilocal, and hybrid\nfunctionals. The extended Hubbard functional produces increased phonon\nvelocities and lifetimes, and thus lattice thermal conductivities compared to\nlocal and semilocal functionals, agreeing with experiments very well.\nConsidering that our computational demand is comparable to simple local\nfunctionals, this work thus suggests a way to perform high-throughput\nelectronic and structural calculations with a higher accuracy.",
        "positive": "Physically informed machine-learning algorithms for the identification\n  of two-dimensional atomic crystals: First isolated in 2004, graphene monolayers display unique properties and\npromising technological potential in next generation electronics,\noptoelectronics, and energy storage. The simple yet effective methodology,\nmechanical exfoliation followed by optical microscopy inspection, used for\nfabricating graphene has been exploited to discover many more two-dimensional\n(2D) atomic crystals which show distinct physical properties from their bulk\ncounterpart, opening the new era of materials research. However, manual\ninspection of optical images to identify 2D flakes has the clear drawback of\nlow-throughput and hence is impractical for any scale-up applications of 2D\nsamples, albert their fascinating physical properties. Recent integration of\nhigh-performance machine-learning, usually deep learning, techniques with\noptical microscopy has accelerated flake identification. Despite the\nadvancement brought by deep learning algorithms, their high computational\ncomplexities, large dataset requirements, and more importantly, opaque\ndecision-making processes limit their accessibilities. As an alternative, we\ninvestigate more transparent tree-based machine-learning algorithms with\nfeatures that mimic color contrast for the automated identification of\nexfoliated 2D atomic crystals (e.g., MoSe2) under different optical settings.\nWe compare the success and physical nature of the decisions of these tree-based\nalgorithms to ResNet, a Convolutional Neural Network (CNN). We show that\ndecision trees, gradient boosted decision trees, and random forests can\nsuccessfully classify optical images of thin materials with transparent\ndecisions that rely on physical image features and do not suffer from extreme\noverfitting and large dataset requirements."
    },
    {
        "anchor": "Unrestricted Hartree-Fock theory of Wigner crystals: We demonstrate that unrestricted Hartree-Fock theory applied to electrons in\na uniform potential has stable Wigner crystal solutions for $r_s \\geq 1.44$ in\ntwo dimensions and $r_s \\geq 4.5$ in three dimensions. The correlation energies\nof the Wigner crystal phases are considerably smaller than those of the fluid\nphases at the same density.",
        "positive": "Control of the magnetism and magnetic anisotropy of a single-molecule\n  magnet with an electric field: Through systematics density functional calculations, the mechanism of the\nsubstrate induced spin reorientation transition in FePc/O-Cu(110) was explained\nin terms of charge transfer and rearrangement of Fe-d orbitals. Moreover, we\nfound giant magnetoelectric effects in this system, manifested by the sensitive\ndependences of its magnetic moment and magnetic anisotropy energy on external\nelectric field. In particular, the direction of magnetization of FePc/O-Cu(110)\nis switchable between in-plane and perpendicular axes, simply by applying an\nexternal electric field of 0.5 eV/{\\AA} along the surface normal."
    },
    {
        "anchor": "Oxygen impurities in NiAl: Relaxation effects: We have used a full-potential linear muffin-tin orbital method to calculate\nthe effects of oxygen impurities on the electronic structure of NiAl. Using the\nsupercell method with a 16-atom supercell we have investigated the cases where\nan oxygen atom is substitutionally placed at either a nickel or an aluminum\nsite. Full relaxation of the atoms within the supercell was allowed. We found\nthat oxygen prefers to occupy a nickel site over an aluminum site with a site\nselection energy of 138 mRy (21,370 K). An oxygen atom placed at an aluminum\nsite is found to cause a substantial relaxation of its nickel neighbors away\nfrom it. In contrast, this steric repulsion is hardly present when the oxygen\natom occupies the nickel site and is surrounded by aluminum neighbors. We\ncomment on the possible relation of this effect to the pesting degradation\nphenomenon (essentially spontaneous disintegration in air) in nickel\naluminides.",
        "positive": "Phenolic Resin Dual-Use Stamps for Capillary Stamping and Decal Transfer\n  Printing: We report an optimized two-step thermopolymerization process carried out in\ncontact with micropatterned molds that yields porous phenolic resin dual-use\nstamps with topographically micropatterned contact surfaces. With these stamps,\ntwo different parallel additive substrate manufacturing methods can be\nexecuted: capillary stamping and decal transfer microlithography. Under\nmoderate contact pressures, the porous phenolic resin stamps are used for\nnon-destructive ink transfer to substrates by capillary stamping. Continuous\nink supply through the pore systems to the contact surfaces of the porous\nphenolic resin stamps enables multiple successive stamp-substrate contacts for\nlithographic ink deposition under ambient conditions. No deterioration of the\nquality of the deposited pattern occurs and no interruptions for ink\nreplenishment are required. Under high contact pressure, porous phenolic resin\nstamps are used for decal transfer printing. In this way, the tips of the\nstamps' contact elements are lithographically transferred to counterpart\nsubstrates. The granular nature of the phenolic resin facilitates the rupture\nof the contact elements upon stamp retraction. The deposited phenolic resin\nmicropatterns characterized by abundance of exposed hydroxyl groups are used as\ngeneric anchoring sites for further application-specific functionalizations. As\nexample, we deposited phenolic resin micropatterns on quartz crystal\nmicrobalance resonators and further functionalized them with polyethylenimine\nfor preconcentration sensing of humidity and gaseous formic acid. We envision\nthat also preconcentration coatings for other sensing methods, such as\nattenuated total reflection infrared spectroscopy and surface plasmon resonance\nspectroscopy, are accessible by this functionalization algorithm"
    },
    {
        "anchor": "Elastic properties of highly anisotropic thin poly(propylene) foams: In this letter, elastic properties of highly anisotropic cellular\npoly(propylene) films are reported. The material shows peculiar elastic\nproperties compared to other foams in the literature. The data is displayed as\nthe relative Young's modulus $E^*/E_s$ versus relative density $\\rho^*/\\rho_s$.\nAlmost all the data from the literature are located on the region\n$E^*/E_s=(\\rho^*/\\rho_s)^n$ with $1\\le n\\le6$. The introduced material on the\nother hand have lower relative Young's modulus at high relative densities,\n$n\\ge6$.",
        "positive": "A DFT Investigation of the Electronic and Optical Properties of\n  Pentadiamond: Recently, a new carbon 3D carbon allotrope named pentadiamond was proposed.\nPentadiamond is composed of carbon atoms in mixed sp$^2$ and sp$^3$-like\nhybridization. In this work, we have carried out a detailed investigation of\nthe electronic and optical properties of pentadiamond structure using\nfirst-principles (DFT) methods. Our results show that pentadiamond has an\nindirect bandgap semiconductor of $2.50$ eV with GGA-PBE and $3.31$ eV with\nHSE06. Its static dielectric constant is $4.70$ and the static refractive index\nis $2.16$. Pentadiamond presents low reflectivity, almost 40$\\%$, for\nall-optical spectrum, making it a good structure to be used as a UV collector.\nAlso, pentadiamond exhibits optical activity in the UV range where other carbon\nallotropes, such as diamond and 8-tetra(2,2) tubulane show no activity."
    },
    {
        "anchor": "Monoclinic (Mc) phase and electric field induced phase transformation in\n  BaTiO3: For decades it has been a well-known fact that among the few ferroelectric\ncompounds in the perovskite family namely BaTiO3, KNbO3, PbTiO3 Na1/2Bi1/2TiO3\nthe dielectric and piezoelectric properties of BaTiO3 is considerably higher\nthan the others in polycrystalline form at room temperature. Further, similar\nto ferroelectric alloys exhibiting morphotropic phase boundary, single crystals\nof BaTiO3 exhibits anomalously large piezoelectric response when poled away\nfrom the direction of spontaneous polarization at room temperature. These\nanomalous features in BaTiO3 remained unexplained so far from the structural\nstand point. In this work we have used high resolution synchrotron X-ray powder\ndiffraction, atomic resolution aberration corrected transmission electron\nmicroscopy, in conjunction with a novel powder poling technique, to reveal that\n(i) the equilibrium state of BaTiO3 is characterized by coexistence of a subtle\nmonoclinic (Mc) phase and tetragonal phase, and (ii) strong electric field\ninduces an orthorhombic phase at 300 K. These results suggest that BaTiO3 at\nroom temperature is within an instability regime, and that this instability is\ntherefore the fundamental factor responsible for the anomalous dielectric and\npiezoelectric properties of BaTiO3 as compared to the other homologous\nferroelectric perovskite compounds. The results demonstrate that pure BaTiO3 at\nroom temperature more akin to lead-based ferroelectric alloys close to the\nmorphotropic phase boundary where polarization rotation and field induced\nferroelectric-ferroelectric phase transformations play fundamental role in\ninfluencing the piezoelectric behavior.",
        "positive": "The influence of strut waviness on the tensile response of lattice\n  materials: Recent advances in additive manufacturing methods make it possible, for the\nfirst time, to manufacture complex micro-architectured solids that achieve\ndesired stress versus strain responses. Here, we report experimental\nmeasurements and associated finite element (FE) calculations on the effect of\nstrut shape upon the tensile response of two-dimensional (2D) lattices made\nfrom low-carbon steel sheets. Two lattice topologies are considered: (i) a\nstretching-dominated triangular lattice and (ii) a bending-dominated hexagonal\nlattice. It is found that strut waviness can enhance the ductility of each\nlattice, particularly for bending-dominated hexagonal lattices. Manufacturing\nimperfections such as undercuts have a small effect on the ductility of the\nlattices but can significantly reduce the ultimate tensile strength. FE\nsimulations provide additional insight into these observations and are used to\nconstruct design maps to aid the design of lattices with specified strength and\nductility."
    },
    {
        "anchor": "Modelling photothermal induced resonance microscopy: the role of\n  interface thermal resistances: Infrared (IR) nanospectroscopy by photothermal induced resonance (PTIR) is a\nnovel experimental technique that combines the nanoscale resolution granted by\natomic force microscopy (AFM) and the chemical labelling made possible by IR\nabsorption spectroscopy. While the technique has developed enormously over the\nlast decade from an experimental point of view, the theoretical modelling of\nthe signal still varies significantly throughout the literature and misses a\nsolid benchmark. Here, we report an analysis focused on the electromagnetic and\nthermal simulations of a PTIR experiment. Thanks to a control experiment where\nthe signal is acquired as a function of the thickness of a polymer film and for\ndifferent tip geometries, we find clear evidence that the interface thermal\nresistances play a key role in the determination of the measured signal and\nshould therefore always be accounted for by any quantitative modelling.",
        "positive": "The effect of quenching from different temperatures on Bi 0.88 Sb 0.12\n  alloy: Structural, thermal, resistive and magnetic properties of melt quenched Bi\n0.88 Sb 0.12 alloys are reported. The samples are heated at three different\ntemperatures, followed by rapid quenching in liquid nitrogen. Large temperature\ndifference between liquidus and solidus lines, led to microscopic\nin-homogeneity in the alloy. The effect of quenching from different\ntemperatures in polycrystalline Bi 0.88 Sb 0.12 alloy has been studied. The\nparameters such as strain, unit cell volume, and resistivity are found to\nincrease with temperature. Thermal variation of resistivity depicts non\nmonotonic temperature dependence. The total negative susceptibility increases\nand band gap of semiconducting Bi 0.88 Sb 0.12 samples decreases with\nincreasing temperature."
    },
    {
        "anchor": "Metrology of small particles and solute clusters by atom probe\n  tomography: Atom probe tomography (APT) is routinely used for analyzing\nproperty-enhancing particles in the nanometer-size range and below, and plays a\nprominent role in the analysis of solute clusters. However, the question of how\nwell these small particles are measured has never been addressed because of a\nlack of a reliable benchmark. Here, to address this critical gap, we use an\napproach that allows direct comparison of APT and small-angle (X-Ray)\nscattering (SA(X)S) performed on the same material. We introduce the notion of\nan effective spatial resolution for the analysis of particles, which,\nimportantly in this context, is very different than the technique's inherent\nspatial resolution. This effective resolution is highly specific to the system\nbeing considered, as well as the analysis conditions. There is no hard limit\nbelow which the technique will fail, but particles with a radius of order of\n\\textapprox $2\\sigma=1nm$, i.e. \\textapprox\\num{250} atoms cannot be accurately\nmeasured, even though the particles are detected. This thorough metrological\nassessment of APT in the analysis of particles allows us to discuss the pulse\nspread function of the technique and the physics underpinning its limits. We\nconclude that great care should be taken when analysing solute clusters by APT,\nin particular when reporting particle size and composition.",
        "positive": "Epitaxially Stabilized EuMoO3: A New Itinerant Ferromagnet: Synthesizing metastable phase often opens new functions in materials but is a\nchallenging topic. Thin film techniques have advantages to form materials which\ndo not exist in nature since nonequilibrium processes are frequently utilized.\nIn this study, we successfully synthesize epitaxially stabilized new compound\nof perovskite Eu2+Mo4+O3 as a thin film form by a pulsed laser deposition.\nAnalogous perovskite SrMoO3 is a highly conducting paramagnetic material, but\nEu2+ and Mo4+ are not compatible in equilibrium and previous study found more\nstable pyrochlore Eu23+Mo24+O7 prefers to form. By using isostructural\nperovskite substrates, the gain of the interface energy between the film and\nthe substrate stabilizes the matastable EuMoO3 phase. This compound exhibits\nhigh conductivity and large magnetic moment, originating from Mo 4d2 electrons\nand Eu 4f7 electrons, respectively. Our result indi-cates the epitaxial\nstabilization is effective not only to stabilize crystallographic structures\nbut also to from a new compound which contains unstable combinations of ionic\nvalences in bulk form."
    },
    {
        "anchor": "Origin of the excitonic recombinations in hexagonal boron nitride by\n  spatially resolved cathodoluminescence spectroscopy: The excitonic recombinations in hexagonal boron nitride (hBN) are\ninvestigated with spatially resolved cathodoluminescence spectroscopy in the UV\nrange. Cathodoluminescence images of an individual hBN crystallite reveals that\nthe 215 nm free excitonic line is quite homogeneously emitted along the\ncrystallite whereas the 220 nm and 227 nm excitonic emissions are located in\nspecific regions of the crystallite. Transmission electron microscopy images\nshow that these regions contain a high density of crystalline defects. This\nsuggests that both the 220 nm and 227 nm emissions are produced by the\nrecombination of excitons bound to structural defects.",
        "positive": "Local Optical Spectroscopy in Quantum Confined Systems: A Theoretical\n  Description: A theoretical description of local absorption is proposed in order to\ninvestigate spectral variations on a length scale comparable with the extension\nof the relevant quantum states. A general formulation is derived within the\ndensity-matrix formalism including Coulomb correlation, and applied to the\nprototypical case of coupled quantum wires. The results show that excitonic\neffects may have a crucial impact on the local absorption with implications for\nthe spatial resolution and the interpretation of near-field optical spectra."
    },
    {
        "anchor": "Topological Surface States Originated Spin-Orbit Torques in Bi2Se3: Three dimensional topological insulator bismuth selenide (Bi2Se3) is expected\nto possess strong spin-orbit coupling and spin-textured topological surface\nstates, and thus exhibit a high charge to spin current conversion efficiency.\nWe evaluate spin-orbit torques in Bi2Se3/Co40Fe40B20 devices at different\ntemperatures by spin torque ferromagnetic resonance measurements. As\ntemperature decreases, the spin-orbit torque ratio increases from ~ 0.047 at\n300 K to ~ 0.42 below 50 K. Moreover, we observe a significant out-of-plane\ntorque at low temperatures. Detailed analysis indicates that the origin of the\nobserved spin-orbit torques is topological surface states in Bi2Se3. Our\nresults suggest that topological insulators with strong spin-orbit coupling\ncould be promising candidates as highly efficient spin current sources for\nexploring next generation of spintronic applications.",
        "positive": "Charge carrier dynamics in bulk MoS2 crystal studied by transient\n  absorption microscopy: We report a transient absorption microscopy study of charge carrier dynamics\nin bulk MoS2 crystals at room temperature. Charge carriers are injected by\ninterband absorption of a 555-nm pulse, and probed by measuring differential\nreflection of a time-delayed and spatially scanned 660-nm pulse. We find an\nintervalley transfer time of about 0.35 ps, an energy relaxation time of hot\ncarriers on the order of 50 ps, and a carrier lifetime of 180 ps. By monitoring\nthe spatiotemporal dynamics of carriers, we obtained a diffusion coefficient of\nthermalized electrons of 4.2 cm2/s, corresponding to a mobility of 170 cm2/Vs.\nWe also observed a time-varying diffusion coefficient of hot carriers."
    },
    {
        "anchor": "Anomalous delocalization of resonant states in graphene \\& the vacancy\n  magnetic moment: Carbon atom vacancies in graphene give rise to a local magnetic moment of\n$\\sigma+\\pi$ origin, whose magnitude is yet uncertain and debated. Partial\nquenching of $\\pi$ magnetism has been ubiquitously reported in periodic\n$first-principles$ calculations, with magnetic moments scattered in the range\n1.0 - 2.0 $\\mu_{B}$, slowly converging to the lower or the upper end, depending\non how the diluted limit is approached. By contrast, (ensemble) density\nfunctional theory calculations on cluster models neatly converge to the value\nof $2$ $\\mu_{B}$ when increasing the system size. This stunning discrepancy has\nsparked an ongoing debate about the role of defect-defect interactions and\nself-doping, and about the importance of the self-interaction-error in the\ndensity-functional-theory description of the vacancy-induced states.\n  Here, we settle this puzzle by showing that the problem has a fundamental,\nmono-electronic origin which is related to the special (periodic) arrangement\nof defects that results when using the slab-supercell approach. Specifically,\nwe report the existence of resonant states that are $anomalously$ delocalized\nover the lattice and that make the $\\pi$ midgap band $unphysically$ dispersive,\nhence prone to self-doping and quenching of the $\\pi$ magnetism. Hybrid\nfunctionals fix the problem by widening the gap between the spin-resolved $\\pi$\nmidgap bands, without reducing their artificial widths. As a consequence, while\nreconciling the magnetic moment with expectations, they predict a\nspin-splitting which is one order of magnitude larger than found in\nexperiments.",
        "positive": "Symmetry Dependent Scattering by Minority Interface Resonance States in\n  Single-crystal Magnetic Tunnel Junctions: Symmetry dependent scattering effect by minority interface resonance states\n(IRS) has been evidenced in full-epitaxial Fe/MgO/Fe magnetic tunnel junctions\n(MTJs). Two types of samples with and without carbon doped bottom Fe/MgO\ninterface were fabricated to represent two different types of IRS in the\nminority channel in the vicinity of the Fermi level. By analysis of the first-\nprinciples calculated local density of states (LDOS) and the temperature\ndependence of conductance in parallel configuration at low bias, we show that\nthe IRS in the carbon free sample is dominated by the delta5 symmetry. This has\na major contribution on the majority deltai to delta5 channel scattering and\nexplains the enhancement of the delta5 conductance in the parallel\nconfiguration at low temperature. Furthermore, the spectral composition of the\nIRS in the carbon doped interface is found to be dominated by the delta1\nsymmetry, which is responsible for the suppression of delta5 channel in the\nparallel conductance."
    },
    {
        "anchor": "Simple empirical model for vibrational spectra of single-wall carbon\n  nanotubes: A simple empirical model and approach are introduced for calculation of the\nvibrational spectra of arbitrary single wall carbon nanotubes. Differently from\nthe frequently used force constants description, the model employs only\ninvariant quantities such as variations of lengths and angles. All the salient\nqualitative features of vibrational spectra of nanotubes naturally follow from\nthe vibrational Hamiltonian of graphene upon its isometric mapping onto a\ncylindrical surface and without any ad hoc corrections. A qualitative\ndifference with previous results is found in a parabolic, rather than a linear,\nlong wavelength dispersion of the transverse acoustic modes of the nanotubes.\nThe parabolic dispersion is confirmed and elucidated in the provided continuum\nanalysis of the vibrations. We also discuss and use an alternative definition\nof the nanotube unit cell with only two carbons per cell that illustrates a\n\"true\" longitudinal periodicity of the nanotubes, and of the corresponding\nBrillouin zone.",
        "positive": "A general solution for accelerating screw dislocations in arbitrary slip\n  systems with reflection symmetry: Solutions to the differential equations of linear elasticity in the continuum\nlimit in arbitrary crystal symmetry are known only for steady-state\ndislocations of arbitrary character, i.e. line defects moving at constant\nvelocity. Troubled by singularities at certain `critical' velocities (typically\nclose to certain sound speeds), these dislocation fields are thought to be too\nidealized, and divergences are usually attributed to neglecting the finite size\nof the core and to the restriction to constant velocity. In the isotropic\nlimit, accelerating pure screw and edge dislocations were studied some time\nago. A generalization to anisotropic crystals has been attempted for pure screw\nand edge dislocations only for some special cases. This work aims to fill the\ngap of deriving a general anisotropic solution for pure screw dislocations\napplicable to slip systems featuring a reflection symmetry, a prerequisite to\nstudying pure screw dislocations without mixing with edge dislocations. Further\ngeneralizations to arbitrary mixed dislocations as well as regularizations of\nthe dislocation core are beyond the scope of this paper and are left for future\nwork."
    },
    {
        "anchor": "Field-driven dynamics of magnetic Hopfions: We present micromagnetic simulations on resonant spin wave modes of magnetic\nHopfions up to 15 GHz driven by external magnetic fields. A sharp transition is\nfound around 32 mT coinciding with a transition from Hopfions to magnetic\ntorons. The modes exhibit characteristic amplitudes in frequency space\naccompanied by unique localization patterns in real space, and are found to be\nrobust to damping around topological features, particularly vortex lines in\nHopfions and Bloch points in torons. The marked differences in spin wave\nspectra between Hopfions, torons and target skyrmions can serve as fingerprints\nin future experimental validation studies of these novel 3d topological spin\ntextures.",
        "positive": "Evidence of deep water penetration in silica during stress corrosion\n  fracture: We measure the thickness of the heavy water layer trapped under the stress\ncorrosion fracture surface of silica using neutron reflectivity experiments. We\nshow that the penetration depth is 65-85 \\aa ngstr\\\"{o}ms, suggesting the\npresence of a damaged zone of $\\approx$ 100 \\aa ngstr\\\"{o}ms extending ahead of\nthe crack tip during its propagation. This estimate of the size of the damaged\nzone is compatible with other recent results."
    },
    {
        "anchor": "Ehrlich-Schwoebel Effect on the Growth Dynamics of GaAs(111)A surfaces: We present a detailed characterization of the growth dynamics of\nGa(Al)As(111)A surfaces. We develop a theoretical growth model that well\ndescribes the observed behavior on the growth parameters and underlines the\nEhrlich-Schwoebel barrier as leading factor that determines the growth\ndynamics. On such basis we analyze the factors that lead to the huge observed\nroughness on such surface orientations and we identify the growth conditions\nthat drive the typical three-dimensional growth of Ga(Al)As(111)A towards\natomically flat surface. GaAs/AlGaAs quantum wells realized on optimized\nsurface (<0.2 nm roughness) show a record low emission linewidth of 4.5 meV.",
        "positive": "Ballistic conductance of magnetic Co and Ni nanowires with ultrasoft\n  pseudo-potentials: The scattering-based approach for calculating the ballistic conductance of\nopen quantum systems is generalized to deal with magnetic transition metals as\ndescribed by ultrasoft pseudo-potentials. As an application we present\nquantum-mechanical conductance calculations for monatomic Co and Ni nanowires\nwith a magnetization reversal. We find that in both Co and Ni nanowires, at the\nFermi energy, the conductance of $d$ electrons is blocked by a magnetization\nreversal, while the $s$ states (one per spin) are perfectly transmitted. $d$\nelectrons have a non-vanishing transmission in a small energy window below the\nFermi level. Here, transmission is larger in Ni than in Co."
    },
    {
        "anchor": "The surfactant effect in semiconductor thin film growth: The theoretical and experimental status of surfactant mediated semiconductor\nepitaxial growth is reviewed. We discuss homoepitaxy as well as heteroepitaxy,\nand emphasize in particular issues related to the mechanism by which\nsurfactants suppress growth of three dimensional islands in heteroepitaxy. We\nargue that the dominant mechanism is passivation of island edges, which leads\nto suppression of attachment and detachment of atoms to and from island edges.",
        "positive": "Relation between the strength and dimensionality of defect-free carbon\n  crystals: On the basis of ab-initio simulations, the value of strength of interatomic\nbonds in one-, two- and three-dimensional carbon crystals is obtained. It is\nshown that decreasing in dimensionality of crystal gives rise to nearly linear\nincrease in strength of atomic bonds. It is ascertained that growth of strength\nof the crystal with a decrease in it dimensionality is due to both a reduction\nin coordination number of atom and increase in the angle between the directions\nof atomic bonds. Based on these data, it is substantiated that the\none-dimensional crystals have maximum strength, and strength of carbyne is the\nabsolute upper limit of strength of materials"
    },
    {
        "anchor": "Nucleation of Al Nanocrystals in Solute-Substituted Al Metallic Glasses\n  I: Structural characterization: Primary crystallization in high Al-content metallic glasses is driven by\nnanometer-diameter regions with internal structure similar to fcc Al.\nComparison of fluctuation electron microscopy (FEM) data to FEM simulations of\nfcc Al clusters dispersed in a dense-random packed matrix is used to extract\nthe diameter and volume fraction of the ordered regions in a Al88Y7Fe5 base\nglass and in glasses with 1 at.% Cu substituted for Y or Al. The size and\ndensity of nanocrystals were measured as a function of isothermal annealing\ntime for the same alloys. The volume fraction of crystalline material grows\nunder isothermal annealing, so the phase transformation is not purely grain\ncoarsening, but the crystalline volume fraction is lower than the volume\nfraction of ordered regions in the as-quenched samples, so not all of the\nordered regions act as nuclei. Changes in diameter and volume fraction of the\nordered regions with alloying are correlated with changes in the\ncrystallization temperature, nucleation rate, and nanocrystal density. No\nevidence for phase separation is observed, and FEM simulations from a molecular\ndynamics quenched structural model of similar composition do not show the\nfeatures observed in experiment.",
        "positive": "Enhanced ultrafast relaxation rate in the Weyl semimetal phase of\n  $\\mathbf{MoTe_2}$ measured by time-and angle-resolved photoelectron\n  spectroscopy: $\\mathrm{MoTe_2}$ has recently been shown to realize in its low-temperature\nphase the type-II Weyl semimetal (WSM). We investigated by time- and angle-\nresolved photoelectron spectroscopy (tr-ARPES) the possible influence of the\nWeyl points in the electron dynamics above the Fermi level $\\mathrm{E_F}$, by\ncomparing the ultrafast response of $\\mathrm{MoTe_2}$ in the trivial and\ntopological phases. In the low-temperature WSM phase, we report an enhanced\nrelaxation rate of electrons optically excited to the conduction band, which we\ninterpret as a fingerprint of the local gap closure when Weyl points form. By\ncontrast, we find that the electron dynamics of the related compound\n$\\mathrm{WTe_2}$ is slower and temperature-independent, consistent with a\ntopologically trivial nature of this material. Our results shows that tr-ARPES\nis sensitive to the small modifications of the unoccupied band structure\naccompanying the structural and topological phase transition of\n$\\mathrm{MoTe_2}$."
    },
    {
        "anchor": "Characterizing dielectric properties of ultra-thin films using\n  superconducting coplanar microwave resonators: We present an experimental approach for cryogenic dielectric measurements on\nultra-thin insulating films. Based on a coplanar microwave waveguide design we\nimplement superconducting quarter-wave resonators with inductive coupling,\nwhich allows us to determine the real part $\\varepsilon_1$ of the dielectric\nfunction at GHz frequencies and for sample thicknesses down to a few nm. We\nperform simulations to optimize resonator coupling and sensitivity, and we\ndemonstrate the possibility to quantify $\\varepsilon_1$ with a conformal\nmapping technique in a wide sample-thickness and $\\varepsilon_1$-regime.\nExperimentally we determine $\\varepsilon_1$ for various thin-film samples\n(photoresist, MgF$_2$, and SiO$_2$) in the thickness regime of nm up to $\\mu\nm$. We find good correspondence with nominative values and we identify the\nprecision of the film thickness as our predominant error source. Additionally\nwe present a temperature-dependent measurement for a SrTiO$_3$ bulk sample,\nusing an in-situ reference method to compensate for the temperature dependence\nof the superconducting resonator properties.",
        "positive": "Graphene Contacts to a HfSe2/SnS2 Heterostructure: Placing graphene on SnS2 results in significant charge transfer, on the order\nof 10^13/cm^2, from the graphene to the SnS2, and the charge transfer results\nin a negative Schottky barrier contact for electron injection from the graphene\ninto the SnS2 conduction band. However, due to the s-px,y composition of the\nSnS2 conduction band, the coupling between the SnS2 and the graphene is\nrelatively weak. A third layer, HfSe2, placed between the SnS2 and the\ngraphene, serves as a matrix element matching layer, since it has strong\ncoupling to both the graphene and the SnS2. It increases the coupling to the\ngraphene by a factor of 10, and it has little effect on the negative Schottky\nbarrier height, since the conduction band wavefucntion of the SnS2 / HfSe2 is a\ncoherent superposition of the orbitals from the two individual layers, such\nthat there is no energy barrier for an electron to move between the two layers.\nThis paper first investigates the electronic properties of the heterostructure\nbilayer SnS2 / HfSe2 in the presence of an applied vertical electric field, and\nthen it investigates the trilayer systems of BN / SnS2 / HfSe2 and graphene /\nSnS2 / HfSe2. A tunneling Hamiltonian estimate of the the contact resistance of\nthe graphene to the SnS2 / HfSe2 heterostructure indicates an excellent\nlow-resistance contact."
    },
    {
        "anchor": "Charge Storage in Cation Incorporated \u03b1-MnO2: Electrochemical supercapacitors utilizing {\\alpha}-MnO2 offer the possibility\nof both high power density and high energy density. Unfortunately, the\nmechanism of electrochemical charge storage in {\\alpha}-MnO2 and the effect of\noperating conditions on the charge storage mechanism are generally not well\nunderstood. Here, we present the first detailed charge storage mechanism of\n{\\alpha}-MnO2 and explain the capacity differences between {\\alpha}- and\n{\\beta}-MnO2 using a combined theoretical electrochemical and band structure\nanalysis. We identify the importance of the band gap, work function, the point\nof zero charge, and the tunnel sizes of the electrode material, as well as the\npH and stability window of the electrolyte in determining the viability of a\ngiven electrode material. The high capacity of {\\alpha}-MnO2 results from\ncation induced charge-switching states in the band gap that overlap with the\nscanned potential allowed by the electrolyte. The charge-switching states\noriginate from interstitial and substitutional cations (H+, Li+, Na+, and K+)\nincorporated into the material. Interstitial cations are found to induce\ncharge-switching states by stabilizing Mn-O antibonding orbitals from the\nconduction band. Substitutional cations interact with O[2p] dangling bonds that\nare destabilized from the valence band by Mn vacancies to induce\ncharge-switching states. We calculate the equilibrium electrochemical\npotentials at which these states are reduced and predict the effect of the\nelectrochemical operating conditions on their contribution to charge storage.\nThe mechanism and theoretical approach we report is general and can be used to\ncomputationally screen new materials for improved charge storage via ion\nincorporation.",
        "positive": "Accuracy and transferability of GAP models for tungsten: We introduce interatomic potentials for tungsten in the bcc crystal phase and\nits defects within the Gaussian Approximation Potential (GAP) framework, fitted\nto a database of first principles density functional theory (DFT) calculations.\nWe investigate the performance of a sequence of models based on databases of\nincreasing coverage in configuration space and showcase our strategy of\nchoosing representative small unit cells to train models that predict\nproperties only observable using thousands of atoms. The most comprehensive\nmodel is then used to calculate properties of the screw dislocation, including\nits structure, the Peierls barrier and the energetics of the\nvacancy-dislocation interaction. All software and raw data are available at\nwww.libatoms.org."
    },
    {
        "anchor": "Critical Oxide Thickness for Efficient Single-walled Carbon Nanotube\n  Growth on Silicon Using Thin SiO2 Diffusion Barriers: The ability to integrate carbon nanotubes, especially single-walled carbon\nnanotubes, seamlessly onto silicon would expand the range of applications\nconsiderably. Though direct integration using chemical vapor deposition is the\nsimplest method, the growth of single-walled carbon nanotubes on bare silicon\nand on ultra-thin oxides is greatly inhibited due to the formation of a\nnon-catalytic silicide. Using x-ray photoelectron spectroscopy, we show that\nsilicide formation occurs on ultra-thin oxides due to thermally activated metal\ndiffusion through the oxide. Silicides affect the growth of single-walled\nnanotubes more than multi-walled nanotubes due to the increased kinetics at the\nhigher single-walled nanotube growth temperature. We demonstrate that nickel\nand iron catalysts, when deposited on clean silicon or ultra-thin silicon\ndioxide layers, begin to form silicides at relatively low temperatures, and\nthat by 900C, all of the catalyst has been incorporated into the silicide,\nrendering it inactive for subsequent single-walled nanotube growth. We further\nshow that a 4 nm silicon dioxide layer is the minimum diffusion barrier\nthickness which allows for efficient single-walled nanotube growth.",
        "positive": "Probing the LDA-1/2 method as a starting point for $G_0W_0$ calculations: Employing the $G_0W_0$ approximation of Hedin's $GW$ approach one can obtain\nquasi-particle energies of extended systems and molecules with good accuracy.\nHowever, for many materials, semi-local exchange-correlation functionals are\nunsatisfactory starting points for $G_0W_0$ calculations. Hybrid functionals\noften improve upon them, but at a substantially higher computational cost. As\nan alternative, we suggest the LDA-1/2 method, which provides reasonable band\ngaps, without being computationally involved. In this work, we systematically\ncompare 3 starting points for $G_0W_0$: LDA, PBE0, and LDA-1/2. A selection of\nsolids is chosen for this benchmark: C, Si, SiC, AlP, LiF, MgO, Ne, Ar, GaN,\nGaAs, CdS, ZnS, and ZnO. We demonstrate that LDA-1/2 is a good starting point\nin most cases, reducing the mean absolute error of band gaps by 50% when\ncompared to the other 2 functionals."
    },
    {
        "anchor": "Crystal Templating with Mutually Miscible Solvents: A Simple Path to\n  Hierarchical Porosity: Ice templating, a route where ice crystals are used to template\nmacroporosity, has been used to process a variety of materials with one level\nof macropores. We demonstrate here a variant of ice templating based on the\nsolidification of mutually miscible solvents. The solidification of different\nphases, each defined by their own size and morphology, provides a simple\none-step processing route for materials with hierarchical porosity defined by\nup to three levels of macroporosity. These concepts are demonstrated with both\nceramic (yttria-stabilized zirconia) and polymer (polyvinyl alcohol) materials.",
        "positive": "Topology of chalcogen chains: We investigate the topological properties of the helical atomic chains\noccurring in elemental selenium and tellurium. We postulate a realistic model\nthat includes spin-orbit interaction and show this to be topologically\nnon-trivial, with a topological invariant protected by a crystalline symmetry.\nWe describe the end-states, which are orbitally polarized, with an orbital\ndensity modulation strongly peaked at the edge. Furthermore, we propose a\nsimplified model that decomposes into three orbital chains, allowing us to\ndefine a topological invariant protected by a crystalline symmetry. We contrast\nthis result with recent observations made for the orbital Su-Schrieffer-Heeger\nmodel containing a $p$-orbital zigzag chain."
    },
    {
        "anchor": "Optical response of silver clusters and their hollow shells from\n  Linear-Response TDDFT: We present a study of the optical response of compact and hollow icosahedral\nclusters containing up to 868 silver atoms by means of time-dependent density\nfunctional theory. We have studied the dependence on size and morphology of\nboth the sharp plasmonic resonance at 3-4 eV (originated mainly from\n$sp$-electrons), and the less studied broader feature appearing in the 6-7 eV\nrange (interband transitions). An analysis of the effect of structural\nrelaxations, as well as the choice of exchange correlation functional (local\ndensity versus generalized gradient approximations) both in the ground state\nand optical response calculations is also presented. We have further analysed\nthe role of the different atom layers (surface versus inner layers) and the\ndifferent orbital symmetries on the absorption cross-section for energies up to\n8 eV. We have also studied the dependence on the number of atom layers in\nhollow structures. Shells formed by a single layer of atoms show a pronounced\nred shift of the main plasmon resonances that, however, rapidly converge to\nthose of the compact structures as the number of layers is increased. The\nmethods used to obtain these results are also carefully discussed. Our\nmethodology is based on the use of localized basis (atomic orbitals, and\natom-centered- and dominant- product functions), which bring several\ncomputational advantages related to their relatively small size and the\nsparsity of the resulting matrices. Furthermore, the use of basis sets of\natomic orbitals also brings the possibility to extend some of the standard\npopulation analysis tools (e.g., Mulliken population analysis) to the realm of\noptical excitations. Some examples of these analyses are described in the\npresent work.",
        "positive": "Hybrid Simulation between Molecular Dynamics and Binary Collision\n  Approximation Codes for Hydrogen injection onto Carbon Materials: Molecular dynamics (MD) simulation with modified Brenner's reactive empirical\nbond order (REBO) potential is a powerful tool to investigate plasma wall\ninteraction on divertor plates in a nuclear fusion device. However, MD\nsimulation box's size is less than several nm for the performance of a\ncomputer. To extend the size of the MD simulation, we develop a hybrid\nsimulation code between MD code using REBO potential and binary collision\napproximation (BCA) code. Using the BCA code instead of computing all particles\nwith a high kinetic energy for every step in the MD simulation, considerable\ncomputation time is saved. By demonstrating a hydrogen atom injection on a\ngraphite by the hybrid simulation code, it is found that the hybrid simulation\ncode works efficiently in a large simulation box."
    },
    {
        "anchor": "Theory of Electron Spin Relaxation in ZnO: Doped ZnO is a promising material for spintronics applications. For such\napplications, it is important to understand the spin dynamics and particularly\nthe spin coherence of this II-VI semiconductor. The spin lifetime $\\tau_{s}$\nhas been measured by optical orientation experiments, and it shows a surprising\nnon-monotonic behavior with temperature. We explain this behavior by invoking\nspin exchange between localized and extended states. Interestingly, the effects\nof spin-orbit coupling are by no means negligible, in spite of the relatively\nsmall valence band splitting. This is due to the wurtzite crystal structure of\nZnO. Detailed analysis allows us to characterize the impurity binding energies\nand densities, showing that optical orientation experiments can be used as a\ncharacterization tool for semiconductor samples.",
        "positive": "Glass-like thermal conductivity in SrTiO3 thermoelectrics induced by\n  A-site vacancies: The introduction of A-site vacancies in SrTiO3 results in a glass-like\nthermal conductivity while Nb substituted samples maintains good electrical\nconductivity. This unexpected result brings SrTiO3 one step closer to being a\nhigh-performing phonon-glass electron-crystal thermoelectric material."
    },
    {
        "anchor": "Two-photon Indirect Optical Injection and Two-color Coherent Control in\n  Bulk Silicon: Using an empirical pseudopotential description of electron states and an\nadiabatic bond charge model for phonon states in bulk silicon, we theoretically\ninvestigate two-photon indirect optical injection of carriers and spins and\ntwo-color coherent control of the motion of the injected carriers and spins.\nFor two-photon indirect carrier and spin injection, we identify the selection\nrules of band edge transitions, the injection in each conduction band valley,\nand the injection from each phonon branch at 4 K and 300 K. At 4 K, the TA\nphonon-assisted transitions dominate the injection at low photon energies, and\nthe TO phonon-assisted at high photon energies. At 300 K, the former dominates\nat all photon energies of interest. The carrier injection shows anisotropy and\nlinear-circular dichroism with respect to light propagation direction. For\nlight propagating along the $<001>$ direction, the carrier injection exhibits\nvalley anisotropy, and the injection into the $Z$ conduction band valley is\nlarger than that into the $X/Y$ valleys. For $\\sigma^-$ light propagating along\nthe $<001>$ ($<111>$) direction, the degree of spin polarization gives a\nmaximum value about 20% (6%) at 4 K and -10% (20%) at 300 K, and at both\ntemperature shows abundant structure near the injection edges due to\ncontributions from different phonon branches. Forthe two-color coherent current\ninjection with an incident optical field composed of a fundamental frequency\nand its second harmonic, the response tensors of the electron (hole) charge and\nspin currents are calculated at 4 K and 300 K. We show the current control for\nthree different polarization scenarios. The spectral dependence of the maximum\nswarm velocity shows that the direction of charge current reverses under\nincrease in photon energy.",
        "positive": "Quantum oscillations in a topological insulator Bi_{1-x}Sb_{x}: We have studied transport and magnetic properties of Bi_{1-x}Sb_x, which is\nbelieved to be a topological insulator - a new state of matter where an\ninsulating bulk supports an intrinsically metallic surface. In nominally\ninsulating Bi_{0.91}Sb_{0.09} crystals, we observed strong quantum oscillations\nof the magnetization and the resistivity originating from a Fermi surface which\nhas a clear two-dimensional character. In addition, a three-dimensional Fermi\nsurface is found to coexist, which is possibly due to an unusual coupling of\nthe bulk to the surface. This finding demonstrates that quantum oscillations\ncan be a powerful tool to directly probe the novel electronic states in\ntopological insulators."
    },
    {
        "anchor": "Room-temperature magnetocaloric effect in La0.7Sr0.3Mn1-xM'xO3 (M'=Al,\n  Ti): Magnetic entropy and adiabatic temperature changes in and above the\nroom-temperature region has been measured for La0.7Sr0.3Mn1-xM'xO3 (M' = Al,\nTi) by means of magnetization and heat capacity measurements in magnetic fields\nup to 6 T. The magnetocaloric effect becomes largest at the ferromagnetic\nordering temperature Tc that is tuned to ~300 K by the substitution of Al or Ti\nfor Mn. While the substitution of Al for Mn drastically reduces the entropy\nchange, it extends considerably the working temperature span and improves the\nrelative cooling power. The magnetocaloric effect seems to be only lightly\naffected by Ti substitution. Although manganites have been considered potential\nfor magnetic refrigerants, the magnetocaloric effect in these materials is\nlimited due to the existence of short-range ferromagnetic correlations above\nTc.",
        "positive": "Quasicrystal nucleation in an intermetallic glass-former: The discovery of quasicrystals 30 years ago challenged our understanding of\norder at the atomic scale. While quasicrystals possess long-range orientational\norder they lack translation periodicity. Structurally complex, yet crystalline\nintermetallics and (bulk) metallic glasses represent competing states of\ncondensed matter among metallic phases, including peculiarities like the\nq-glass. Considerable progress has been made in their structure elucidation and\nin identifying factors governing their formation; comparatively less is known\nabout their interrelation. Moreover, studies bridging the spatial scales from\natoms to the macroscale are scarce. Here we report on the homogeneous\nnucleation of a single quasicrystalline seed of decagonal symmetry and its\ncontinuous growth into a tenfold twinned dendritic microstructure.\nElectrostatic levitation was applied to undercool melts of glass-forming NiZr,\nobserving single crystallization events with a high-speed camera; with a\nstatistical evaluation of 200 consecutive thermal cycles suggesting homogeneous\nnucleation. The twinned dendritic microstructure, apparent in electron\nbackscatter diffraction maps, results from the symmetry breaking of an\nessentially 2D decagonal quasicrystalline cluster. Conserving its long-range\norientational order, our distortion-free twin model merges a common structure\ntype for binary intermetallic compounds, with interatomic distances of alike\natoms scaled by the golden ratio, and spiral growth resembling phyllotaxis.\nNiZr represents a missing link connecting quasicrystals and multiple twinned\nstructures sheding light on intermediate states of order between glasses,\ncrystals and their twins, and quasicrystals."
    },
    {
        "anchor": "Unified Treatment of Magnons and Excitons in Monolayer CrI$_3$ from\n  Many-Body Perturbation Theory: We present first principles calculations of the two-particle excitation\nspectrum of CrI$_3$ using many-body perturbation theory including spin-orbit\ncoupling. Specifically, we solve the Bethe-Salpeter equation, which is\nequivalent to summing up all ladder diagrams with static screening and it is\nshown that excitons as well as magnons can be extracted seamlessly from the\ncalculations. The resulting optical absorption spectrum as well as the magnon\ndispersion agree very well with recent measurements and we extract the\namplitude for optical excitation of magnons resulting from spin-orbit\ninteractions. Importantly, the results do not rely on any assumptions on the\nmicroscopic magnetic interactions such as Dzyaloshinskii-Moriya (DM), Kitaev or\nbiquadratic interactions and we obtain a model independent estimate of the gap\nbetween acoustic and optical magnons of 0.3 meV. In addition, we resolve the\nmagnon wavefunction in terms of band transitions and show that the magnon\ncarries a spin that is significantly smaller than $\\hbar$. This highlights the\nimportance of terms that do not commute with $S^z$ in any Heisenberg model\ndescription.",
        "positive": "Crystal structure, stability and optoelectronic properties of the\n  organic-inorganic wide bandgap perovskite CH3NH3BaI3: Candidate for\n  transparent conductor applications: Structural stability, electronic structure and optical properties of\nCH3NH3BaI3 hybrid perovskite is examined both from theory as well as\nexperiment. Solution-processed thin films of CH3NH3BaI3 exhibited a high band\ngap of approximately 3.87 eV, which is in excellent agreement with the\ntheoretical estimate of 4 eV. Also, the XRD patterns of the thin films match\nwell with the l-peaks of the simulated pattern obtained from the relaxed unit\ncell of CH3NH3BaI3, crystallizing in the I4/mcm space group, with lattice\nparameters, a = 9.30 A, c = 13.94 A. Atom projected density of state and band\nstructure calculations reveal the conduction and valence band edges to be\ncomprised primarily of Barium d-orbitals and Iodine p-orbitals, respectively.\nThe larger band gap of CH3NH3BaI3 compared to CH3NH3PbI3 can be attributed to\nthe lower electro-negativity coupled with the lack of d-orbitals in the valence\nband of Ba{2+}. A more detailed analysis reveals the excellent chemical and\nmechanical stability of CH3NH3BaI3 against humidity, unlike its lead halide\ncounterpart, which degrades under such conditions. The dopability of the\nCH3NH3BaI3 compound e.g. by doping La on the Ba site combined with its\nstructural and mechanical stability under the ambient conditions, suggests this\ncompound as a promising candidate for transparent conductor applications,\nespecially for all perovskite solar cells."
    },
    {
        "anchor": "Structural characterization of as-deposited cesium iodide films studied\n  by X-ray diffraction and transmission electron microscopy techniques: In the present work, cesium iodide (CsI) thin films of different thickness\nhave been prepared by thermal evaporation technique. The crystallite size and\ngrain size of these films are compared by using X-ray diffraction (XRD) profile\nanalysis as well as by transmission electron microscopy (TEM) counting,\nrespectively. These two methods provide less deviation between crystallite size\nand grain size in the case of thin CsI films of 4 nm, but there is\ncomparatively large difference in case of thicker CsI films (20 nm, 100 nm and\n500 nm). It indicates that dislocations are arranged in a configuration which\ncauses small orientational difference between two adjacent coherent regions.\nThe size obtained from XRD corresponds to two separate regions, whereas in the\nTEM micrograph the two regions may seem to correspond one region particularly\nin case of thicker films. Other physical parameters such as strain, stress and\ndeformation energy density are also estimated precisely for the prominent XRD\npeaks of thicker CsI films in the range $2\\theta = 20^{0}-80^{0}$ by using a\nmodified Williamson-Hall (W-H) analysis assuming uniform deformation model\n(UDM), uniform deformation stress model (UDSM) and uniform deformation energy\ndensity model (UDEDM).",
        "positive": "Theoretical studies on mechanical and electronic properties of\n  $s$-triazine sheet: Mechanical and electronic properties of $s$-triazine are studied using\nfirst-principles calculations based on density functional theory. The in-plane\nstiffness and bulk modulus for $s$-triazine sheet are found to be less than\nthat of heptazine. The reduction can be related to the nature of the covalent\nbonds connecting the adjacent sheets and the number of atoms per unit cell. The\nPoisson's ratio of $s$-triazine is half the value to that of graphene.\nAdditionally, the calculated values of the two critical strains (elastic and\nyielding points) of $s$-triazine sheet are in the same order of magnitude to\nthat for heptazine which was calculated using MD simulations in the literature.\nIt is also demonstrated that $s$-triazine sheet can withstand larger tension in\nthe plastic region. These results established a stable mechanical property for\n$s$-triazine sheet. We found a linear relationship of bandgap as a function of\nbi-axial tensile strain within the harmonic elastic region. The reduced steric\nrepulse of the lone pairs ($\\mathrm{p}_x$-, $\\mathrm {p}_y$-) causes the\n$\\mathrm {p}_z$-like orbital to shift to high energy, and consequently an\nincrease in the bandgap. We find no electronic properties modulation of the\n$s$-triazine sheet under electric field up to a peak value of 10 V/nm. Such\nnoble properties may be useful in future nanomaterial applications."
    },
    {
        "anchor": "Visualizing Temperature-Dependent Phase Stability in High Entropy Alloys: High Entropy Alloys (HEAs) contain near equimolar amounts of five or more\nelements and are a compelling space for materials design. Great emphasis is\nplaced on identifying HEAs that form a homogeneous solid-solution, but the\ndesign of such HEAs is hindered by the difficulty of navigating stability\nrelationships in high-component spaces. Traditional phase diagrams use\nbarycentric coordinates to represent composition axes, which require D = (N -\n1) spatial dimensions to represent an N-component system, meaning that HEA\nsystems with N > 4 components cannot be readily visualized. Here, we propose\nforgoing barycentric composition axes in favor of two energy axes: a\nformation-energy axis and a 'reaction energy' axis. These Inverse Hull Webs\noffer an information-dense 2D representation that successfully capture complex\nphase stability relationships in N > 4 component systems. We use our new\ndiagrams to visualize the transition of HEA solid-solutions from\nhigh-temperature stability to metastability upon quenching, and identify\nimportant thermodynamic features that are correlated with the persistence or\ndecomposition of metastable HEAs.",
        "positive": "Magnetization dynamics in Fe$_x$Co$_{1-x}$ in presence of chemical\n  disorder: In this paper, we present a theoretical formulation of magnetization dynamics\nin disordered binary alloys based on Kubo linear response theory interfaced\nwith the combination of seamlessly three approaches; density functional based\ntight-binding linear muffin-tin orbitals, generalized recursion and Augmented\nspace formalism. We apply this method to study the magnetization dynamics in\nchemically disordered Fe$_x$Co$_{1-x}$ ($x$ = 0.2, 0.5, 0.8) alloys. We\nreported that the magnon energies decrease with an increase in Co\nconcentration. Significant magnon softening has been observed in\nFe$_{20}$Co$_{80}$ at the Brillouin zone boundary. The magnon-electron\nscattering increases with increasing Co content which in turn modifies the\nhybridization between the Fe and Co atoms. This reduces the exchange energy\nbetween the atoms and soften down the magnon energy. The lowest magnon lifetime\nin found in Fe$_{50}$Co$_{50}$, where disorder is maximum. This clearly\nindicates that the damping of magnon energies in Fe$_x$Co$_{1-x}$ is governed\nby the hybridization between Fe and Co whereas the magnon lifetime is\ncontrolled by disorder configuration. Our atomistic spin dynamics simulations\nshow a reasonable agreement with our theoretical approach in magnon dispersion\nfor different alloy compositions."
    },
    {
        "anchor": "Magnetic Properties of NbSi2N4, VSi2N4, and VSi2P4 Monolayers: The recent demonstration of MoSi2N4 and its exceptional stability to air,\nwater, acid, and heat has generated intense interest in this family of\ntwo-dimensional (2D) materials. Among these materials, NbSi2N4, VSi2N4, and\nVSi2P4 are semiconducting, easy-plane ferromagnets with negligible in-plane\nmagnetic anisotropy. They thus satisfy a necessary condition for exhibiting a\ndissipationless spin superfluid mode. The Curie temperatures of monolayer\nVSi2P4 and VSi2N4 are determined to be above room temperature based on Monte\nCarlo and density functional theory calculations. The magnetic moments of\nVSi2N4 can be switched from in-plane to out-of-plane by applying tensile\nbiaxial strain or electron doping.",
        "positive": "Conformal Titanium Nitride in a Porous Silicon Matrix: a Nanomaterial\n  for In-Chip Supercapacitors: Today's supercapacitor energy storages are typically discrete devices aimed\nfor printed boards and power applications. The development of autonomous sensor\nnetworks and wearable electronics and the miniaturisation of mobile devices\nwould benefit substantially from solutions in which the energy storage is\nintegrated with the active device. Nanostructures based on porous silicon (PS)\nprovide a route towards integration due to the very high inherent surface area\nto volume ratio and compatibility with microelectronics fabrication processes.\nUnfortunately, pristine PS has limited wettability and poor chemical stability\nin electrolytes and the high resistance of the PS matrix severely limits the\npower efficiency. In this work, we demonstrate that excellent wettability and\nelectro-chemical properties in aqueous and organic electrolytes can be obtained\nby coating the PS matrix with an ultra-thin layer of titanium nitride by atomic\nlayer deposition. Our approach leads to very high specific capacitance (15\nF/cm$^3$), energy density (1.3 mWh/cm$^3$), power density (up to 214 W/cm$^3$)\nand excellent stability (more than 13,000 cycles). Furthermore, we show that\nthe PS-TiN nanomaterial can be integrated inside a silicon chip monolithically\nby combining MEMS and nanofabrication techniques. This leads to realisation of\nin-chip supercapacitor, i.e., it opens a new way to exploit the otherwise\ninactive volume of a silicon chip to store energy."
    },
    {
        "anchor": "Local chemical bonding and structural properties in Ti3AlC2 MAX phase\n  and Ti3C2Tx MXene probed by Ti 1s X-ray absorption spectroscopy: The chemical bonding within the transition-metal carbide materials MAX phase\nTi3AlC2 and MXene Ti3C2Tx is investigated by X-ray absorption near-edge\nstructure (XANES) and extended X-ray absorption fine structure (EXAFS)\nspectroscopies. MAX phases are inherently nanolaminated materials that consist\nof alternating layers of Mn+1Xn and monolayers of an A-element from the IIIA or\nIVA group in the periodic table, where M is a transition metal and X is either\ncarbon or nitrogen. Replacing the A-element with surface termination species Tx\nwill separate the Mn+1Xn-layers forming two-dimensional (2D) flakes of\nMn+1XnTx. For Ti3C2Tx the Tx corresponds to fluorine (F) and oxygen (O)\ncovering both sides of every single 2D Mn+1Xn-flake. The Ti K-edge (1s) XANES\nof both Ti3AlC2 and Ti3C2Tx exhibit characteristic pre-edge absorption regions\nof C 2p - Ti 3d hybridization with clear crystal-field splitting's while the\nmain-edge absorption features originate from the Ti 1s -> 4p excitation, where\nonly the latter shows sensitivity towards the fcc-site occupation of the\ntermination species. The coordination numbers obtained from EXAFS show that\nTi3AlC2 and Ti3C2Tx are highly anisotropic with a strong in-plane contribution\nfor Ti and with a dynamic out-of-plane contribution from the Al monolayers and\ntermination species, respectively. As shown in the temperature-dependent\nmeasurements, the O contribution shifts to shorter bond length while the F\ndiminishes as the temperature is raised from room temperature up to 750\n{\\deg}C.",
        "positive": "How Do You Want That Insulator?: A normal insulator is turned into an exotic topological insulator by tuning\nits elemental composition."
    },
    {
        "anchor": "X-ray diffraction with micrometer spatial resolution for highly\n  absorbing samples: X-ray diffraction with high spatial resolution is commonly used to\ncharacterize (poly-)crystalline samples with, for example, respect to local\nstrain, residual stress, grain boundaries and texture. However, the\ninvestigation of highly absorbing samples or the simultaneous assessment of\nhigh-Z materials by X-ray fluorescence have been limited due to the utilisation\nof low photon energies. Here, we report on a goniometer-based setup implemented\nat the P06 beamline of PETRA III that allows for micrometer spatial resolution\nwith a photon energy of 35 keV and above. A highly focused beam was achieved by\nusing compound refractive lenses and high precision sample manipulation was\nenabled by a goniometer that allows for up to 5D scans (3 rotations & 2\ntranslations). As experimental examples, we demonstrate the determination of\nlocal strain variations in martensitic steel samples with micrometer spatial\nresolution as well as the simultaneous elemental distribution for high-Z\nmaterials in a thin film solar cell. Our proposed approach allows users from\nthe materials science community to determine micro-structural properties even\nin highly absorbing samples.",
        "positive": "High fidelity simulation of the mechanical behavior of closed-cell\n  polyurethane foams: The mechanical behavior of closed-cell foams in compression is analyzed by\nmeans of the finite element simulation of a representative volume element of\nthe microstructure. The digital model of the foam includes the most relevant\ndetails of the microstructure (relative density, cell size distribution and\nshape, fraction of mass in the struts and cell walls and strut shape), while\nthe numerical simulation takes into account the influence of the gas pressure\nin the cells and of the contact between cell walls and struts during crushing.\nThe model was validated by comparison with experimental results on isotropic\nand anisotropic polyurethane foams and it was able to reproduce accurately the\ninitial stiffness, the plateau stress and the hardening region until full\ndensification in isotropic and anisotropic foams. Moreover, it also provided\ngood estimations of the energy dissipated and of the elastic energy stored in\nthe foam as a function of the applied strain. Based on the simulation results,\na simple analytical model was proposed to predict the mechanical behavior of\nclosed-cell foams taking into the effect of the microstructure and of the gas\npressure. An example of application of the simulation tool is presented to\ndesign foams with an optimum microstructure from the viewpoint of energy\nabsorption for packaging."
    },
    {
        "anchor": "Enhanced radiation damage tolerance of amorphous interphase and grain\n  boundary complexions in Cu-Ta: Amorphous interfacial complexions are particularly resistant to radiation\ndamage and have been primarily studied in alloys with good glass-forming\nability, yet recent reports suggest that these features can form even in\nimmiscible alloys such as Cu-Ta under irradiation. In this study, the\nmechanisms of damage production and annihilation due to primary knock-on atom\ncollisions are investigated for amorphous interphase and grain boundaries in a\nCu-Ta alloy using atomistic simulations. Amorphous complexions, in particular\namorphous interphase complexions that separate Cu and Ta grains, result in less\nresidual defect damage than their ordered counterparts. Stemming from the\nnanophase chemical separation in this alloy, the amorphous complexions exhibit\na highly heterogeneous distribution of atomic excess volume, as compared to a\ngood glass former like Cu-Zr. Complexion thickness, a tunable structural\ndescriptor, plays a vital role in damage resistance. Thicker interfacial films\nare more damage-tolerant because they alter the defect production rate due to\ndifferences in intrinsic displacement threshold energies during the collision\ncascade. Overall, the findings of this work highlight the importance of\ninterfacial engineering in enhancing the properties of materials operating in\nradiation-prone environments and the promise of amorphous complexions as\nparticularly radiation damage-tolerant microstructural features.",
        "positive": "Monodomain to polydomain transition in ferroelectric PbTiO3 thin films\n  with La0.67Sr0.3MnO3 electrodes: Finite size effects in ferroelectric thin films have been probed in a series\nof epitaxial perovskite c-axis oriented PbTiO3 films grown on thin\nLa0.67Sr0.33MnO3 epitaxial electrodes. The film thickness ranges from 480 down\nto 28 A (7 unit cells). The evolution of the film tetragonality c/a, studied\nusing high resolution x-ray diffraction measurements, shows first a decrease of\nc/a with decreasing film thickness followed by a recovery of c/a at small\nthicknesses. This recovery is accompanied by a change from a monodomain to a\npolydomain configuration of the polarization, as directly demonstrated by\npiezoresponse atomic force microscopy measurements."
    },
    {
        "anchor": "Numerical simulation of magnetization process in antiferromagnetic\n  ferromagnetic bilayer with compensated interface: The properties of antiferromagnetic ferromagnetic bilayer have been studied\nusing self-consistent mean-field approximation for Heisenberg Hamiltonian. The\nperpendicular exchange coupling has been revealed in a bilayer with a\ncompensated interface. For a uniform antiferromagnetic film a symmetrical\nhysteresis loop has been calculated, because the transverse instability\ndevelops within the antiferromagnetic film at certain critical value of\nexternal magnetic field. On the other hand, shifted hysteresis loop with a\nfinite exchange bias field has been obtained for a non-uniform\nantiferromagnetic film consisting of various domains with perpendicular\ndirections of the easy anisotropy axes.",
        "positive": "Band gap tuning and orbital mediated electron phonon coupling in\n  $HoFe_{1-x}Cr_xO_3$: We report on the evidenced orbital mediated electron phonon coupling and band\ngap tuning in HoFe1-xCrxO3 compounds. From the room temperature Raman\nscattering, it is apparent that the electron-phonon coupling is sensitive to\nthe presence of both the Fe and Cr at the B-site. Essentially, an Ag like local\noxygen breathing mode is activated due to the charge transfer between Fe3+ -\nCr3+ at around 670 cm-1, this observation is explained on the basis of\nFranck-Condon (FC) mechanism. Optical absorption studies infer that there\nexists a direct band gap in the HoFe1-xCrxO3 compounds. Decrease in band gap\nuntil x = 0.5 is ascribed to the broadening of the oxygen p orbitals as a\nresult of the induced spin disorder due to Fe3+ and Cr3+ at B site. In\ncontrast, the increase in band gap above x = 0.5 is explained on the basis of\nthe reduction in the available unoccupied d - orbitals of Fe3+ at the\nconduction band. We believe that above results would be helpful for the\ndevelopment of the optoelectronic devices based on the ortho-ferrites."
    },
    {
        "anchor": "Importance of Catalyst Stability vis-\u00e0-vis Hydrogen Peroxide Formation\n  Rates in PEM Fuel Cell Electrodes: The role of catalyst stability on the adverse effects of hydrogen peroxide\n(H2O2) formation rates in a proton exchange membrane fuel cell (PEMFC) is\ninvestigated for Pt, Pt binary (PtX, X = Co, Ru, Rh, V, Ni) and ternary (PtCoX,\nX = Ir, Rh) catalysts. The selectivity of these catalysts towards H2O2\nformation in the oxygen reduction reaction (ORR) was measured on a rotating\nring disc electrode. These measured values were used in conjunction with local\noxygen and proton concentrations to estimate local H2O2 formation rates in a\nPEMFC anode and cathode. The effect of H2O2 formation rates on the most active\nand durable of these catalysts (PtCo and PtIrCo) on Nafion membrane durability\nwas studied using a single-sided membrane electrode assembly (MEA) with a\nbuilt-in reference electrode. Fluoride ion concentration in the effluent water\nwas used as an indicator of the membrane degradation rate. PtIrCo had the least\nfluorine emission rate (FER) followed by PtCo/KB and Pt/KB. Though PtCo and\nPtIrCo show higher selectivity for H2O2 formation than unalloyed Pt, they did\nnot contribute to membrane degradation. This result is explained in terms of\ncatalyst stability as measured in potential cycling tests in liquid electrolyte\nas well as in a functional PEM fuel cell.",
        "positive": "Crystal orientation relation and macroscopic surface roughness in\n  hetero-epitaxially grown graphene on Cu/mica: A clean, flat and orientation-identified graphene on a substrate is in high\ndemand for graphene electronics. In this study, the hetero-epitaxial graphene\ngrowth on Cu(111)/mica(001) by chemical vapor deposition is investigated to\ncheck the applicability for the top-gate insulator research on graphene as well\nas the graphene channel research by transferring graphene on SiO2/Si\nsubstrates. After adjusting the graphene-growth condition, the surface\nroughness of the graphene/Cu/mica substrate and the average smooth area are\n~0.34 nm and ~100 um2, respectively. The orientation of graphene in the\ngraphene/Cu/mica substrate can be identified by the hexagonal void morphology\nof Cu. Moreover, we demonstrate the relatively high mobility of ~4500 cm2V-1s-1\nin graphene transferred on the SiO2/Si substrate. These results suggest that\nthe present graphene/Cu/mica substrate can be used for top-gate insulator\nresearch on graphene."
    },
    {
        "anchor": "Faceting Oscillations in Nano-Ferroelectrics: We observe periodic faceting of 8-nm diameter ferroelectric disks on a 10 s\ntime-scale when thin Pb(Zr0.52Ti0.48)O3 (PZT) film is exposed to constant\nhigh-resolution transmission electron microscopy (HRTEM) beams. The oscillation\nis between circular disk geometry and sharply faceted hexagons. The behavior is\nanalogous to that of spin structure and magnetic domain wall velocity\noscillations in permalloy [A. Bisig et al., Nature Commun. 4, 2328 (2013)],\ninvolving overshoot and de-pinning from defects [C. P. Amann, et al., J. Rheol.\n57, 149-175 (2013)].",
        "positive": "Sharing data between facilities: using the NeXus time-of-flight powder\n  diffractometer file format: NeXus is an international standard data format intended to reduce the need\nfor redundant software development efforts in the neutron and x-ray scattering\ncommunities. As the NeXus standard matures it is starting to be used at\nlaboratories for storing raw data. The Manuel Lujan Jr. Neutron Scattering\nCenter (MLNSC) at Los Alamos National Laboratory and the Intense Pulsed Neutron\nSource (IPNS) at Argonne National Laboratory have been working with NeXus in an\neffort to share data and software. MLNSC is now writing files compliant with\nNeXus and the Integrated Spectral Analysis Workbench (ISAW) software from IPNS\nis being used with this data. Problems can arise if the standard is interpreted\nin different ways and information that belongs in the file is not accounted for\nin the standard. This paper will discuss an inter-laboratory collaboration in\nrelation to a maturing data standard."
    },
    {
        "anchor": "Low voltage local strain enhanced switching of magnetic tunnel junctions: Strain-controlled modulation of the magnetic switching behavior in magnetic\ntunnel junctions (MTJs) could provide the energy efficiency needed to\naccelerate the use of MTJs in memory, logic, and neuromorphic computing, as\nwell as an additional way to tune MTJ properties for these applications.\nState-of-the-art CoFeB-MgO based MTJs still require too high voltages to alter\ntheir magnetic switching behavior with strain. In this study, we demonstrate\nstrain-enhanced field switching of nanoscale MTJs through electric field\ncontrol via voltage applied across local gates. The results show that\nrecord-low voltage down to 200 mV can be used to control the switching field of\nthe MTJ through enhancing the magnetic anisotropy, and that tunnel\nmagnetoresistance is linearly enhanced with voltage through straining the\ncrystal structure of the tunnel barrier. These findings underscore the\npotential of electric field manipulation and strain engineering as effective\nstrategies for tailoring the properties and functionality of nanoscale MTJs.",
        "positive": "Efficient adiabatic demagnetization refrigeration to below 50 mK with\n  UHV compatible Ytterbium diphosphates $A$YbP$_2$O$_7$ ($A=$Na, K): Attaining milli-Kelvin temperatures is often a prerequisite for the study of\nnovel quantum phenomena and the operation of quantum devices. Adiabatic\ndemagnetization refrigeration (ADR) is an effective, easy and sustainable\nalternative to evaporation or dilution cooling with the rare and\nsuper-expensive $^3$He. Paramagnetic salts, traditionally used for mK-ADR,\nsuffer from chemical instability related to water of crystallization. We report\nsynthesis, characterization as well as low-temperature magnetization and\nspecific heat measurements of two new UHV compatible candidate materials\nNaYbP$_2$O$_7$ and KYbP$_2$O$_7$. Utilizing the PPMS at 2 K, the ADR of\nsintered pellets with Ag powder admixture starting at 5 T yields base\ntemperatures (warm-up times) of 45 mK (55 min) and 37 mK (35 min) for\nNaYbP$_2$O$_7$ and KYbP$_2$O$_7$, respectively, slightly advantageous to\nKBaYb(BO$_3$)$_2$ (45 mK and 40 min) studied under similar conditions."
    },
    {
        "anchor": "Graphene bilayer with a twist: electronic structure: Electronic properties of bilayer and multilayer graphene have generally been\ninterpreted in terms of AB or Bernal stacking. However, it is known that many\ntypes of stacking defects can occur in natural and synthetic graphite; rotation\nof the top layer is often seen in scanning tunneling microscopy (STM) studies\nof graphite. In this paper we consider a graphene bilayer with a relative small\nangle rotation between the layers and calculate the electronic structure near\nzero energy in a continuum approximation. Contrary to what happens in a AB\nstacked bilayer and in accord with observations in epitaxial graphene we find:\n(a) the low energy dispersion is linear, as in a single layer, but the Fermi\nvelocity can be significantly smaller than the single layer value; (b) an\nexternal electric field, perpendicular to the layers, does not open an\nelectronic gap",
        "positive": "Dimer rattling mode induced low thermal conductivity in an excellent\n  acoustic conductor: A solid with larger sound speeds exhibits higher lattice thermal conductivity\n(k_{lat}). Diamond is a prominent instance where its mean sound speed is 14400\nm s-1 and k_{lat} is 2300 W m-1 K-1. Here, we report an extreme exception that\nCuP2 has quite large mean sound speeds of 4155 m s-1, comparable to GaAs, but\nthe single crystals show a very low lattice thermal conductivity of about 4 W\nm-1 K-1 at room temperature, one order of magnitude smaller than GaAs. To\nunderstand such a puzzling thermal transport behavior, we have thoroughly\ninvestigated the atomic structure and lattice dynamics by combining neutron\nscattering techniques with first-principles simulations. Cu atoms form dimers\nsandwiched in between the layered P atomic networks and the dimers vibrate as a\nrattling mode with frequency around 11 meV. This mode is manifested to be\nremarkably anharmonic and strongly scatters acoustic phonons to achieve the low\nk_{lat}. Such a dimer rattling behavior in layered structures might offer an\nunprecedented strategy for suppressing thermal conduction without involving\natomic disorder."
    },
    {
        "anchor": "Localized Excitons in Defective Monolayer Germanium Selenide: Germanium Selenide (GeSe) is a van der Waals-bonded layered material with\npromising optoelectronic properties, which has been experimentally synthesized\nfor 2D semiconductor applications. In the monolayer, due to reduced\ndimensionality and, thus, screening environment, perturbations such as the\npresence of defects have a significant impact on its properties. We apply\ndensity functional theory and many-body perturbation theory to understand the\nelectronic and optical properties of GeSe containing a single selenium vacancy\nin the $-2$ charge state. We predict that the vacancy results in mid-gap \"trap\nstates\" that strongly localize the electron and hole density and lead to sharp,\nlow-energy optical absorption peaks below the predicted pristine optical gap.\nAnalysis of the exciton wavefunction reveals that the 2D Wannier-Mott exciton\nof the pristine monolayer is highly localized around the defect, reducing its\nBohr radius by a factor of four and producing a dipole moment along the\nout-of-plane axis due to the defect-induced symmetry breaking. Overall, these\nresults suggest that the vacancy is a strong perturbation to the system,\ndemonstrating the importance of considering defects in the context of material\ndesign.",
        "positive": "Calculated high-pressure structural properties, lattice dynamics and\n  quasi particle band structures of perovskite fluorides KZnF 3 , CsCaF 3 and\n  BaLiF 3: A detailed study of the high-pressure structural properties, lattice dynamics\nand band structures of perovskite structured fluorides KZnF3, CsCaF3 and BaLiF3\nhas been carried out by means of density functional theory. The calculated\nstructural properties including elastic constants and equation of state agree\nwell with available experimental information. The phonon dispersion curves are\nin good agreement with available experimental inelastic neutron scattering\ndata. The electronic structures of these fluorides have been calculated using\nthe quasi particle self-consistent [Formula: see text] approximation. The\n[Formula: see text] calculations reveal that all the fluorides studied are wide\nband gap insulators, and the band gaps are significantly larger than those\nobtained by the standard local density approximation, thus emphasizing the\nimportance of quasi particle corrections in perovskite fluorides."
    },
    {
        "anchor": "Band alignment of metal/amorphous-oxide interface using atomic orbitals\n  projection of plane-wave: a first principle study at the Al/a-SiO2 interface: Amorphous insulating oxides play a significant role in the contemporary\nelectronic industry. Understanding the band alignment of heterogeneous\ninterfaces containing amorphous structures helps to better control the carrier\ntransport property at the interface. Classical band offset methods developed\npreviously line-up eigenlevels with respect to an ideal bulk reference or\nvacuum level. However, the local disorder of amorphous structures makes the\nbulk reference ambiguous. Therefore, classical methods cannot be applied. In\nthis study, we introduce a new approach based on the Linear Combination of\nAtomic Orbital (LCAO) projection of wave-function to line-up bands at\nmetal/oxide interfaces. The LCAO projection of wave-function accounts for all\nmetal/oxide interface effects, such as build-in voltage, interface dipole,\nvirtual oxide thinning, barrier deformation, etc. Therefore, it provides\naccurate band alignments. Calculations performed at an Al/amorphous-SiO2\nexhibit a good agreement between existing experiments and simulation data. We\nAlso observed a space charge region at the interface resulting in non-linear\nband bending in the oxide, which virtually decreases its thickness, hence\nlowering the dielectric strength.",
        "positive": "Li-doped Beryllonitrene for Enhanced Carbon Dioxide Capture: In recent years, the scientific community has given more and more attention\nto the issue of climate change and global warming, which is largely attributed\nto the massive quantity of carbon dioxide emissions. Thus, the demand for a\ncarbon dioxide capture material is massive and continuously increasing. In this\nstudy, we perform first-principle calculations based on density functional\ntheory to investigate the carbon dioxide capture ability of pristine and doped\nberyllonitrene. Our results show that carbon dioxide had an adsorption energy\nof -0.046 eV on pristine beryllonitrene, so it appears that beryllonitrene has\nextremely weak carbon dioxide adsorption ability. Pristine beryllonitrene could\nbe effectively doped with Lithium atoms, and the resulting Li-doped\nberyllonitrene had much stronger interactions with carbon dioxide than pristine\nberyllonitrene. The adsorption energy for carbon dioxide on Li-doped\nberyllonitrene was -0.408 eV. The adsorption of carbon dioxide on Li-doped\nberyllonitrene greatly changed the charge density, projected density of states,\nand band structure of the material, demonstrating that it was strongly\nadsorbed. This suggests that Li-doping is a viable way to enhance the carbon\ndioxide capture ability of beryllonitrene and makes it a possible candidate for\nan effective CO$_2$ capture material."
    },
    {
        "anchor": "The Origin of Two-dimensional Electron Gas in Zn$_{1-x}$Mg$_x$O/ZnO\n  Heterostructures: Although the two-dimensional electron gas (2DEG) in (001)\nZn$_{1-x}$Mg$_x$O/ZnO heterostructures has been discovered for about twenty\nyears, the origin of the 2DEG is still inconclusive. In the present letter, the\nformation mechanisms of 2DEG near the interfaces of (001) Zn$_{1-x}$Mg$_x$O/ZnO\nheterostructures were investigated via the first-principles calculations\nmethod. It is found that the polarity discontinuity near the interface can\nneither lead to the formation of 2DEG in devices with thick Zn$_{1-x}$Mg$_{x}$O\nlayers nor in devices with thin Zn$_{1-x}$Mg$_{x}$O layers. For the\nheterostructure with thick Zn$_{1-x}$Mg$_{x}$O layers, the oxygen vacancies\nnear the interface introduce a defect band in the band gap, and the top of the\ndefect band overlaps with the bottom of the conduction band, leading to the\nformation of the 2DEG near the interface of the device. For the heterostructure\nwith thin Zn$_{1-x}$Mg$_{x}$O layers, the absorption of hydrogen atoms, oxygen\natoms, or OH groups on the surface of Zn$_{1-x}$Mg$_{x}$O film plays a key role\nfor the formation of 2DEG in the device. Our results manifest the sources of\n2DEGs in Zn$_{1-x}$Mg$_x$O/ZnO heterostructures on the electronic structure\nlevel.",
        "positive": "Nearest-Neighbor Broken Bond Model for Describing the Surface Energies\n  of Transition Metals: In our recent works, we used a nearest-neighbor broken bond (NNBB) model to\nfit the surface energy of Pt, Pd, and Au surfaces [Adv. Theory Simul. 1800127\n(2018)]. It was verified that this model could describe the surface energies of\nabove noble metals with high accuracy. The applications of this model in\nreal-time simulations of equilibrium nanocrystal transformations are in good\nagreements with the experimental observations at macroscopic time scales\nquantitatively. In this work, we want to further verify the generality of the\nNNBB model for other transition metals. All surface tentions and lattice\nconstants were extracted from the database of Materials Project. The number of\nmissing NN bonds of different slabs from low-index surfaces to open surfaces\nwere counted for both surface atoms and subsurface atoms. As presented below,\nlinear relationships between surface energies and missing bonds number are\nfound for all studied elements. The bond energies for different metals are\nobtained through fitting NN bonds and surface energy of different surfaces."
    },
    {
        "anchor": "Stability mechanism of cuboctahedral clusters in UO2: First-principles\n  calculations: The stability mechanism of cuboctahedral clusters in nonstoichiometric\nuranium dioxide is investigated by first-principles LSDA+U method. Calculations\nreveal that the structural stability is inherited from U6O12 molecular cluster\nwhereas the energy gain through occupying its center with an additional oxygen\nmakes the cluster win out by competition with point oxygen interstitials. Local\ndisplacement of the center oxygen along <111> direction also leads the cluster\n8-folded degeneracy and increases relatively the concentration at finite\ntemperatures. But totally, elevation of temperature, i.e., the effect of\nentropy, favors point interstitial over cuboctahedral clusters.",
        "positive": "Oscillations in Rapid Fracture: Experiments of pure tensile fracture in brittle gels reveal a new dynamic\noscillatory instability whose onset occurs at a critical velocity, Vc = 0.87\nCs, where Cs is the shear wave speed. Until Vc crack dynamics are well\ndescribed by linear elastic fracture mechanics (LEFM). These extreme speeds are\nobtained by suppression of the micro-branching instability, which occurs when\nsample thicknesses are made comparable to the minimum micro-branch width. The\nwavelength of these sinusoidal oscillations is independent of the sample\ndimensions, thereby suggesting that a new intrinsic scale exists that is\nunrelated to LEFM."
    },
    {
        "anchor": "Multiple phases in sputtered Cr2CoGa films: By magnetron co-sputtering, thin films of a nominal Cr2CoGa compound were\ndeposited on MgO and MgAl2O4. To achieve crystallisation in the inverse Heusler\nstructure, different heat treatments were tested. Instead of the inverse\nHeusler structure, we observed phase separation and precipitate formation in\ndependence on the heat treatment. The main precipitate is Cr3Ga in A15\nstructure. The remainder forms Co-rich CoGa in the B2 structure and possibly\nCr-rich CoCr in the sigma-phase.",
        "positive": "The Sign of Three: Spin/Charge Density Waves at the Boundaries of\n  Transition Metal Dichalcogenides: One-dimensional grain boundaries of two-dimensional semiconducting {\\MX} (M=\nMo,W; X=S,Se) transition metal di-chalcogenides are typically metallic at room\ntemperature. The metallicity has its origin in the lattice polarization, which\nfor these lattices with $D_{3h}$ symmetry is a topological invariant, and leads\nto one-dimenional boundary states inside the band gap. For boundaries\nperpendicular to the polarization direction, these states are necessarily 1/3\noccupied by electrons or holes, making them susceptible to a metal-insulator\ntransition that triples the translation period. Using density-functional-theory\ncalculations we demonstrate the emergence of combined one-dimensional spin\ndensity/charge density waves of that period at the boundary, opening up a small\nband gap of $\\sim 0.1$ eV. This unique electronic structure allows for soliton\nexcitations at the boundary that carry a fractional charge of $\\pm 1/3\\ e$."
    },
    {
        "anchor": "Enhanced refrigerant capacity and magnetic entropy flattening using a\n  two-amorphous FeZrB(Cu) composite: The temperature dependence of the isothermal magnetic entropy change,\n{\\Delta}SM, and the magnetic field dependence of the refrigerant capacity, RC,\nhave been investigated in a composite system xA+(1-x)B, based on Fe87Zr6B6Cu1\n(A) and Fe90Zr8B2 (B) amorphous ribbons. Under a magnetic field change of 2 T\nthe maximum improvement of the full-width at half maximum of {\\Delta}SM(T)\ncurve (47 and 29 %) and the RC (18 and 23 %), in comparison with those of the\nindividual alloys (A and B), is observed for x \\approx 0.5. Moreover, a\nflattening over 80 K in the {\\Delta}SM(T) curve around room temperature range\nis observed, which is a key feature for an Ericsson magnetic refrigeration\ncycle.",
        "positive": "Nitrogen Doped Graphene Quantum Dots as Possible Substrates to Stabilize\n  Planar Conformer of Au 20 Over its Tetrahedral Conformer: A Systematic DFT\n  Study: Utilizing the strengths of nitrogen doped graphene quantum dot (N-GQD) as a\nsubstrate, here in, we have shown that one can stabilize the catalytically more\nactive planar Au 20 (P-Au 20 ) compared to the thermodynamically more stable\ntetrahedral structure (T-Au 20 ) on an N-GQD. Clearly, this simple route avoids\nthe usage of traditional transition metal oxide substrates which have been\nsuggested and used for stabilizing the planar structure for a long time.\nConsidering the experimental success in the synthesis of N-GQDs and in the\nstabilization of Au nanoparticles on N-doped graphene, we expect our proposed\nmethod to stabilize planar structure will be realized experimentally and will\nbe useful for industrial level applications."
    },
    {
        "anchor": "First principles calculations of anisotropic charge carrier mobilities\n  in organic semiconductor crystals: The orientational dependence of charge carrier mobilities in organic\nsemiconductor crystals and the correlation with the crystal structure are\ninvestigated by means of quantum chemical first principles calculations\ncombined with a model using hopping rates from Marcus theory. A master equation\napproach is presented which is numerically more efficient than the Monte Carlo\nmethod frequently applied in this context. Furthermore, it is shown that the\nwidely used approach to calculate the mobility via the diffusion constant along\nwith rate equations is not appropriate in many important cases. The\ncalculations are compared with experimental data, showing good qualitative\nagreement for pentacene and rubrene. In addition, charge transport properties\nof core-fluorinated perylene bisimides are investigated.",
        "positive": "Imaging structural transitions in organometallic molecules on Ag(100)\n  for solar thermal energy storage: The use of opto-thermal molecular energy storage at the nanoscale creates new\nopportunities for powering future microdevices with flexible synthetic\ntailorability. Practical application of these molecular materials, however,\nrequires a deeper microscopic understanding of how their behavior is altered by\nthe presence of different types of substrates. Here we present single-molecule\nresolved scanning tunneling microscopy imaging of thermally- and\noptically-induced structural transitions in (fulvalene)tetracarbonyldiruthenium\nmolecules adsorbed onto a Ag(100) surface as a prototype system. Both the\nparent complex and the photoisomer display distinct thermally-driven phase\ntransformations when they are in contact with a Ag(100) surface. This behavior\nis consistent with the loss of carbonyl ligands due to strong molecule-surface\ncoupling. Ultraviolet radiation induces marked structural changes only in the\nintact parent complex, thus indicating a photoisomerization reaction. These\nresults demonstrate how stimuli-induced structural transitions in this class of\nmolecule depend on the nature of the underlying substrate."
    },
    {
        "anchor": "Correlation between spin-phonon coupling and magneto-electric effects in\n  CoFe2O4/PMN-PT nanocomposite: Raman Spectroscopy and XMCD study: We have investigated the coupling of lattice with spin via strain\ninteractions in the CoFe2O4/PMN-PT composite system. X-ray diffraction and\nRaman spectroscopic studies illustrate a remarkable modification in\nCoFe2O4lattice across Curie temperature (450 K) of PMN-PT. Subsequently,\nCoFe2O4/PMN-PT composite reveals a sudden drop in magnetic moment across Tc of\nPMN-PT (450 K). However,theindependent CoFe2O4phasedisplaystypical\nferromagnetic behaviour across this temperature. These findings establish\nspin-lattice coupling owing to th interfacial strain transfer between CoFe2O4\nand PMN-PT in composite. The strain intractions leads to magneto-electric\ncoupling, evidenced by measuring magentization and magneto-electric coefficient\nfor the electric field poled and unploed CoFe2O4/PMN-PT composite samples.\nX-ray magnetic circular dichroism (XMCD) analysis establishes that the cation\n(Fe3+/Co2+) redistribution occurs on tetrahedral and octahedral site in the\nelectrically poled CoFe2O4/PMN-PT composite, confirming the coupling between\nmagnetic and electric ordering in the composite. The magneto-electric coupling\ncoefficient alpha vs dc magnetic field curves revealed hysteretic behavior and\nenhanced {\\alpha} values after electric poling, which originates from the\nstrain induced modifications in the magnetic domains configuration of composite\nin the poled samples. These findings suggest that the existence of spin lattice\ncoupling may leads to the mechanism of strong magneto-electric effects via\nstrain interactions in CoFe2O4/PMN-PT composite.",
        "positive": "Role of energetic ions in the growth of fcc and \u03c9 crystalline\n  phases in Ti films deposited by HiPIMS: Titanium (Ti), due to its excellent properties, is widely exploited in thin\nfilm technology that usually leads to the production of {\\alpha}-phase (hcp) Ti\nfilms. In this work, we investigate the phase evolution of Ti films deposited\nby varying type and energy of the film-forming species. To investigate\ndifferent plasma species environments, films with different thicknesses are\ngrown by using conventional Direct Current Magnetron Sputtering (DCMS) and High\nPower Impulse Magnetron Sputtering (HiPIMS). Furthermore, HiPIMS depositions\nwith different substrate bias voltage US (0 V, -300 V and -500 V) are performed\nto investigate different ion energy ranges. Microstructure, morphology and\nresidual stress of the deposited films, as well as the DCMS and HiPIMS plasma\ncomposition, are analysed with different characterization techniques. The DCMS\nsamples exhibit the Ti {\\alpha}-phase only and show a tensile residual stress\ndecreasing with thickness. As far as HiPIMS samples are concerned, a\ncompressive-tensile-compressive (CTC) behavior is observed for residual\nstresses as thickness increases. Specifically, films deposited in low energy\nion conditions (US =0 V) show the presence of the Ti fcc phase up to a maximum\nthickness of about 370 nm. Differently, films deposited under high energy\nconditions (US = -300 V and -500 V) show the nucleation of the Ti\n{\\omega}-phase for thicknesses greater than 260 and 330 nm, respectively. The\nformation of these unusual Ti phases is discussed considering the different\ndeposition conditions."
    },
    {
        "anchor": "A new model of correlated disorder in relaxor ferroelectrics: We propose a simple phenomenological picture to explain the unusual\ndielectric properties of the proto-typical ferroelectric relaxor lead magnesium\nniobate-titanate (PMN-PT). Our model assumes a specific, slowly changing,\ndisplacement pattern of the lead ion, which is indirectly controlled by the\nlow-energy acoustic phonons of the system. The model qualitatively explains in\ngreat detail the temperature, pressure, and electric field dependence of\ndiffuse neutron- and x-ray scattering, as well as the existence of hierachy in\nthe relaxation times of these materials. We furthermore show that the widely\nused concept of polar nanoregions as indiviudal static entities is incompatible\nwith the available body of experimental diffuse scattering results.",
        "positive": "Radiation induced electronic trap states and local structural disorder\n  in van~der~Waals bonded semiconductor crystals: In controlled X-ray irradiation experiments, the formation of trap states in\nthe prototypical van der Waals bonded semiconductor Rubrene is studied\nquantitatively for doses up to 82 Gy (Gy = J/kg). About 100 electronic trap\nstates, located around 0.3 eV above the valence band, are created by each\nabsorbed 8 keV photon which is 2-3 orders of magnitude more than 1 MeV protons\nproduce. Thermal annealing is shown to reduce these traps. Local structural\ndisorder, which has also been induced by other means in different studies, is\nthus identified as a common origin of trap states in van der Waals bonded\nmolecular organic semiconductors."
    },
    {
        "anchor": "Roadmap on Electronic Structure Codes in the Exascale Era: Electronic structure calculations have been instrumental in providing many\nimportant insights into a range of physical and chemical properties of various\nmolecular and solid-state systems. Their importance to various fields,\nincluding materials science, chemical sciences, computational chemistry and\ndevice physics, is underscored by the large fraction of available public\nsupercomputing resources devoted to these calculations. As we enter the\nexascale era, exciting new opportunities to increase simulation numbers, sizes,\nand accuracies present themselves. In order to realize these promises, the\ncommunity of electronic structure software developers will however first have\nto tackle a number of challenges pertaining to the efficient use of new\narchitectures that will rely heavily on massive parallelism and hardware\naccelerators. This roadmap provides a broad overview of the state-of-the-art in\nelectronic structure calculations and of the various new directions being\npursued by the community. It covers 14 electronic structure codes, presenting\ntheir current status, their development priorities over the next five years,\nand their plans towards tackling the challenges and leveraging the\nopportunities presented by the advent of exascale computing.",
        "positive": "Lattice dynamics of anharmonic solids from first principles: An accurate and easily extendable method to deal with lattice dynamics of\nsolids is offered. It is based on first-principles molecular dynamics\nsimulations and provides a consistent way to extract the best possible harmonic\n- or higher order - potential energy surface at finite temperatures. It is\ndesigned to work even for strongly anharmonic systems where the traditional\nquasiharmonic approximation fails. The accuracy and convergence of the method\nare controlled in a straightforward way. Excellent agreement of the calculated\nphonon dispersion relations at finite temperature with experimental results for\nbcc Li and bcc Zr is demonstrated."
    },
    {
        "anchor": "Complex trend of magnetic order in Fe clusters on 4$d$ transition-metal\n  surfaces: We demonstrate the occurrence of compensated spin configurations in Fe\nclusters and monolayers on Ru(0001) and Rh(111) by a combination of X-ray\nmagnetic circular dichroism experiments and first-principles calculations. Our\nresults reveal complex intra-cluster exchange interactions which depend\nstrongly on the substrate 4$d$-band filling, the cluster geometry as well as\nlateral and vertical structural relaxations. The importance of substrate\n4$d$-band filling manifests itself also in small nearest-neighbor exchange\ninteractions in Fe dimers and in an nearly inverted trend of the\nRuderman-Kittel-Kasuya-Yosida coupling constants for Fe adatoms on the Ru and\nRh surface.",
        "positive": "Effects of reabsorption and spatial trap distributions on the radiative\n  quantum efficiencies of ZnO: Ultrafast time-resolved photoluminescence spectroscopy following one- and\ntwo-photon excitation of ZnO powder is used to gain unprecedented insight into\nthe surprisingly high external quantum efficiency of its \"green\" defect\nemission band. The role of exciton diffusion, the effects of reabsorption, and\nthe spatial distributions of radiative and nonradiative traps are comparatively\nelucidated for the ultraviolet excitonic and \"green\" defect emission bands in\nboth unannealed, nanometer-sized ZnO powders and annealed, micrometer-sized\nZnO:Zn powders. We find that the primary mechanism limiting quantum efficiency\nis surface recombination because of the high density of nonradiative surface\ntraps in these powders. It is found that unannealed ZnO has a high density of\nbulk nonradiative traps as well, but the annealing process reduces the density\nof these bulk traps while simultaneously creating a high density of\ngreen-emitting defects near the particle surface. The data are discussed in the\ncontext of a simple rate equation model that accounts for the quantum\nefficiencies of both emission bands. The results indicate how defect\nengineering could improve the efficiency of ultraviolet-excited ZnO:Zn-based\nwhite light phosphors."
    },
    {
        "anchor": "Magnetic relaxation in bilayers of yttrium iron garnet/platinum due to\n  the dynamic coupling at the interface: We show that in ferromagnetic (FM)/normal metal (NM) bilayers the dynamic\ncoupling at the interface transfers an additional magnetic relaxation from the\nheavily damped motion of the conduction electron spins in the NM layer to the\nFM spins. While the FM relaxation rates due to two-magnon scattering and spin\npumping decrease rapidly with increasing FM film thickness, the damping due to\nthe dynamic coupling does not depend on the FM film thickness. The proposed\nmechanism explains the very large broadening of ferromagnetic resonance lines\nin thick films of yttrium iron garnet after deposition of a Pt layer.",
        "positive": "New three-dimensional strain-rate potentials for isotropic porous\n  metals: role of the plastic flow of the matrix: At present, modeling of the plastic response of porous solids is done using\nstress-based plastic potentials. To gain understanding of the combined effects\nof all invariants for general three-dimensional loadings, a strain-rate based\napproach appears more appropriate. In this paper, for the first time strain\nrate-based potentials for porous solids with Tresca and von Mises, matrices are\nobtained. The dilatational response is investigated for general 3-D conditions\nfor both compressive and tensile states using rigorous upscaling methods. It is\ndemonstrated that the presence of voids induces dependence on all invariants,\nthe noteworthy result being the key role played by the plastic flow of the\nmatrix on the dilatational response. If the matrix obeys the von Mises\ncriterion, the shape of the cross-sections of the porous solid with the\noctahedral plane deviates slightly from a circle, and changes very little as\nthe absolute value of the mean strain rate increases. However, if the matrix\nbehavior is described by Tresca's criterion, the shape of the cross-sections\nevolves from a regular hexagon to a smooth triangle with rounded corners.\nFurthermore, it is revealed that the couplings between invariants are very\nspecific and depend strongly on the particularities of the plastic flow of the\nmatrix."
    },
    {
        "anchor": "Tunable layered-magnetism-assisted magneto-Raman effect in a\n  two-dimensional magnet $\\mathrm{CrI_3}$: We use a combination of polarized Raman spectroscopy experiment and model\nmagnetism-phonon coupling calculations to study the rich magneto-Raman effect\nin the two-dimensional (2D) magnet $\\mathrm{CrI_3}$. We reveal a novel\nlayered-magnetism-assisted phonon scattering mechanism below the magnetic onset\ntemperature, whose Raman excitation breaks time-reversal symmetry, has an\nantisymmetric Raman tensor, and follows the magnetic phase transitions across\ncritical magnetic fields, on top of the presence of the conventional phonon\nscattering with symmetric Raman tensors in $N$-layer $\\mathrm{CrI_3}$. We\nresolve in data and by calculations that the 1st-order $A_g$ phonon of\nmonolayer splits into a $N$-fold multiplet in $N$-layer $\\mathrm{CrI_3}$ due to\nthe interlayer coupling ($N$>=2) and that the phonons with the multiple show\ndistinct magnetic field dependence because of their different\nlayered-magnetism-phonon coupling. We further find that such a\nlayered-magnetism-phonon coupled Raman scattering mechanism extends beyond\n1st-order to higher-order multi-phonon scattering processes. Our results on\nmagneto-Raman effect of the 1st-order phonons in the multiplet and the\nhigher-order multi-phonons in $N$-layer $\\mathrm{CrI_3}$ demonstrate the rich\nand strong behavior of emergent magneto-optical effects in 2D magnets and\nunderlines the unique opportunities of new spin-phonon physics in van der Waals\nlayered magnets.",
        "positive": "Modulation Doping via a 2d Atomic Crystalline Acceptor: Two-dimensional (2d) nano-electronics, plasmonics, and emergent phases\nrequire clean and local charge control, calling for layered, crystalline\nacceptors or donors. Our Raman, photovoltage, and electrical conductance\nmeasurements combined with \\textit{ab initio} calculations establish the large\nwork function and narrow bands of $\\alpha$-RuCl$_3$ enable modulation doping of\nexfoliated, chemical vapor deposition (CVD), and molecular beam epitaxy (MBE)\nmaterials. Short-ranged lateral doping (${\\leq}65\\ \\text{nm}$) and high\nhomogeneity are achieved in proximate materials with a single layer of \\arucl.\nThis leads to the highest monolayer graphene (mlg) mobilities ($4,900\\\n\\text{cm}^2/ \\text{Vs}$) at these high hole densities ($3\\times10^{13}\\\n\\text{cm}^{-2}$); and yields larger charge transfer to bilayer graphene (blg)\n($6\\times10^{13}\\ \\text{cm}^{-2}$). We further demonstrate proof of principle\noptical sensing, control via twist angle, and charge transfer through hexagonal\nboron nitride (hBN)."
    },
    {
        "anchor": "Transition-Metal Oxide (111) bilayers: Correlated electron systems on a honeycomb lattice have emerged as a fertile\nplayground to explore exotic electronic phenomena. Theoretical and experimental\nwork has appeared to realize novel behavior, including quantum Hall effects and\nvalleytronics, mainly focusing on van der Waals compounds, such as graphene,\nchalcogenides, and halides. In this article, we review our theoretical study on\nperovskite transition-metal oxides (TMOs) as an alternative system to realize\nsuch exotic phenomena. We demonstrate that novel quantum Hall effects and\nrelated phenomena associated with the honeycomb structure could be artificially\ndesigned by such TMOs by growing their heterostructures along the [111]\ncrystallographic axis. One of the important predictions is that such TMO\nheterostructures could support two-dimensional topological insulating states.\nThe strong correlation effects inherent to TM $d$ electrons further enrich the\nbehavior.",
        "positive": "X-ray photoelectron emission microscopy in combination with x-ray\n  magnetic circular dichroism investigation of size effects on field-induced\n  N\u00e9el-cap reversal: X-ray photoelectron emission microscopy in combination with x-ray magnetic\ncircular dichroism is used to investigate the influence of an applied magnetic\nfield on N\\'eel caps (i.e., surface terminations of asymmetric Bloch walls).\nSelf-assembled micron-sized Fe(110) dots displaying a moderate distribution of\nsize and aspect ratios serve as model objects. Investigations of remanent\nstates after application of an applied field along the direction of N\\'eel-cap\nmagnetization give clear evidence for the magnetization reversal of the N\\'eel\ncaps around 120 mT, with a $\\pm$20 mT dispersion. No clear correlation could be\nfound between the value of the reversal field and geometrical features of the\ndots."
    },
    {
        "anchor": "Low temperature heat capacity of Fe_{1-x}Ga_{x} alloys with large\n  magneostriction: The low temperature heat capacity C_{p} of Fe_{1-x}Ga_{x} alloys with large\nmagnetostriction has been investigated. The data were analyzed in the standard\nway using electron ($\\gamma T$) and phonon ($\\beta T^{3}$) contributions. The\nDebye temperature $\\Theta_{D}$ decreases approximately linearly with increasing\nGa concentration, consistent with previous resonant ultrasound measurements and\nmeasured phonon dispersion curves. Calculations of $\\Theta_{D}$ from lattice\ndynamical models and from measured elastic constants C_{11}, C_{12} and C_{44}\nare in agreement with the measured data. The linear coefficient of electronic\nspecific heat $\\gamma$ remains relatively constant as the Ga concentration\nincreases, despite the fact that the magnetoelastic coupling increases. Band\nstructure calculations show that this is due to the compensation of majority\nand minority spin states at the Fermi level.",
        "positive": "Observation of bulk nodal lines in topological semimetal ZrSiS: ZrSiS is the most intensively studied topological nodal-line semimetal\ncandidate, which is proposed to host multiple nodal lines in its bulk\nelectronic structure. However, previous angle-resolved photoemission\nspectroscopy (ARPES) experiments with vacuum ultraviolet lights mainly probed\nthe surface states. Here using bulk-sensitive soft X-ray ARPES, we acquire the\nbulk electronic states of ZrSiS without any interference from surface states.\nOur results clearly show two groups of three-dimensional bulk nodal lines\nlocated on high-symmetry planes and along high-symmetry lines in the bulk\nBrillouin zone, respectively. The nodal lines on high-symmetry planes are\nenforced to pin at the Fermi level by carrier compensation and constitute the\nwhole Fermi surfaces. This means that the carriers in ZrSiS are entirely\ncontributed by nodal-line fermions, suggesting that ZrSiS is a remarkable\nplatform for studying physical properties related to nodal lines."
    },
    {
        "anchor": "Electronic Origins of Large Thermoelectric Power Factor of LaOBiS2-xSex: We examined the electrical transport properties of densified LaOBiS2-xSex,\nwhich constitutes a new family of thermoelectric materials. The power factor\nincreased with increasing concentration of Se, i.e., Se substitution led to an\nenhanced electrical conductivity, without suppression of the Seebeck\ncoefficient. Hall measurements indicated that the low electrical resistivity\nresulted from increases in the carrier mobility, and the decrease in carrier\nconcentration led to large absolute values of the Seebeck coefficient of the\nsystem.",
        "positive": "Analytical description of spin-Rabi oscillation controlled electronic\n  transitions rates between weakly coupled pairs of paramagnetic states with\n  S=1/2: We report on an analytical description of spin-dependent electronic\ntransition rates which are controlled by a radiation induced spin-Rabi\noscillation of weakly spin-exchange and spin-dipolar coupled paramagnetic\nstates (S=1/2). The oscillation components (the Fourier content) of the net\ntransition rates within spin-pair ensembles are derived for randomly\ndistributed spin resonances with account of a possible correlation between the\ntwo distributions that correspond to the two individual pair partners. The\nresults presented here show that when electrically or optically detected Rabi\nspectroscopy is conducted under an increasing driving field B_ 1, the Rabi\nspectrum evolves from a single resonance peak at s=\\Omega_R, where\n\\Omega_R=\\gamma B_1 is the Rabi frequency (\\gamma is the gyromagnetic ratio),\nto three peaks at s= \\Omega_R, s=2\\Omega_R, and at low s<< \\Omega_R. The\ncrossover between the two regimes takes place when \\Omega_R exceeds the\nexpectation value \\delta_0 of the difference of the Zeeman energies within the\npairs, which corresponds to the broadening of the magnetic resonance lines in\nthe presence of disorder caused by hyperfine field or distributions of Lande\ng-factors. We capture this crossover by analytically calculating the shapes of\nall three peaks at arbitrary relation between \\Omega_R and \\delta_0. When the\npeaks are well-developed their widths are \\Delta s ~ \\delta_0^2/\\Omega_R."
    },
    {
        "anchor": "New insights on the formation of supersaturated solid solutions in the\n  Cu Cr system deformed by high pressure torsion: In the Cu Cr system, the formation of supersaturated solid solutions can be\nobtained by severe plastic deformation. Energy dispersive synchrotron\ndiffraction measurements on as deformed Cu Cr samples as a function of the\napplied strain during deformation confirm the formation of supersaturated solid\nsolutions in this usually immiscible system. Due to evaluation of the\ndiffraction data by a newly developed energy dispersive Rietveld program,\nlattice parameter and microstructural parameters such as domain size and\nmicrostrain are determined for as deformed as well as annealed samples. The\nobtained information is used to deepen the understanding of the microstructural\nevolution and the formation of supersaturated solid solutions during severe\nplastic deformation. Complimentary transmission electron microscopy\ninvestigations are furthermore performed to characterize the evolving\nmicrostructure in detail. After annealing at elevated temperatures, the formed\nsolid solutions decompose. Compared to the as deformed state, an enhanced\nhardness combined with a high thermal stability is observed. Possible\nmechanisms for the enhanced hardness are discussed.",
        "positive": "Diminish Electrostatic in Piezoresponse Force Microscopy through longer\n  ultra-stiff tips: Piezoresponse Force Microscopy is a powerful but delicate nanoscale technique\nthat measures the mechanical response resulting from the application of a\nhighly localized electric field. Though mechanical response is normally due to\npiezoelectricity, other physical phenomena, especially electrostatic\ninteraction, can contribute to the signal read. We address this problematic\nthrough the use of longer ultra-stiff probes providing state of the art\nsensitivity, with the lowest electrostatic interaction and avoiding working in\nhigh frequency regime. In order to find this solution we develop a theoretical\ndescription addressing the effects of electrostatic contributions in the total\ncantilever vibration and its quantification for different setups. The theory is\nsubsequently tested in a Periodically Poled Lithium Niobate (PPLN) crystal, a\nsample with well-defined 0deg and 180deg domains, using different commercial\navailable conductive tips. We employ the theoretical description to compare the\nelectrostatic contribution effects into the total phase recorded. Through\nexperimental data our description is corroborated for each of the tested\ncommercially available probes. We propose that a larger probe length can be a\nsolution to avoid electrostatic forces, so the cantilever-sample electrostatic\ninteraction is reduced. For hard oxide samples we propose an ultra-stiff\ncantilever which avoids the use of high frequency voltage but still diminishing\nelectrostatic forces. Our proposed commercially available solution have great\nimplications into avoiding artifacts while studying soft biological samples,\nmultiferroic oxides, and thin film ferroelectric materials and it opens a new\nwindow into tip engineering."
    },
    {
        "anchor": "Optical tweezers with enhanced efficiency based on laser-structured\n  substrates: We present an optical nanotrapping setup that exhibits enhanced efficiency,\nbased on localized plasmonic fields around sharp metallic features. The\nsubstrates consist of laser-structured silicon wafers with quasi-ordered\nmicrospikes on the surface, coated with a thin silver layer. The resulting\noptical traps show orders of magnitude enhancement of the trapping force and\nthe effective quality factor.",
        "positive": "Effect of dipolar interactions on cavity magnon-polaritons: The strong photon-magnon coupling between an electromagnetic cavity and two\nyttrium iron garnet (YIG) spheres has been investigated in the context of a\nstrong mutual dipolar interaction between the spheres. A decrease in the\ncoupling strength between the YIG spheres and the electromagnetic cavity is\nobserved, along with an increase of the total magnetic losses, as the distance\nbetween the spheres is decreased. A model of inhomogeneous broadening of the\nferromagnetic resonance linewidth, partly mitigated by the dipolar narrowing\neffect, reproduces the reduction in the coupling strength observed\nexperimentally. These findings have important implications for the\nunderstanding of strongly coupled photon-magnon system involving densely packed\nmagnetic objects, such as ferromagnetic nanowires arrays, in which the total\ncoupling strength with an electromagnetic cavity might become limited due to\nmutual dipolar interactions."
    },
    {
        "anchor": "Angular Dependence of Spin-Torque Critical Currents in CPP-GMR Read\n  Heads: This paper derives expressions for the critical current at the onset of\nspin-transfer-torque (STT) instability in CPP-GMR read heads, as a function of\nthe relative angle (theta) between the free and reference layer magnetizations.\nIncluding a general angular dependent STT coefficient B(q=cos(theta)) exclusive\nof the angular momentum conserving sin(theta) factor, the critical current is\nfound to depend on both B(q) and dB/dq in the non-collinear case |q| < 1. The\npaper also details the experimental measurement of the angular dependent\ncritical currents on 50-nm sized CPP-GMR devices with synthetic antiferromagnet\npinned layers, and fabricated using e-beam lithography. The measurements are\nconsistent with prior theoretical models of the form B(q) ~ 1/[1+cnst*q], and\nindicate perhaps unanticipated implications for read head operation due to the\ncritical current dependence on dB/dq.",
        "positive": "Mechanism of small-polaron formation in the biferroic YCrO3 doped with\n  calcium: The effects of Ca substitutions on the structure, magnetism and electrical\nproperties of YCrO3 ceramics are investigated by X-ray diffraction, magnetic\nsusceptibility and electrical conductivity measurements. The cell volume\ndecrease occurs through the change from Cr(III) to Cr(IV) as a result of the\ncharge compensation of the Ca doping. No changes are observed in the\nantiferromagnetic transition temperature while strong changes are observed in\nthe transport measurements due to Ca content. The increase of the electrical\nconductivity as well as the decrease of the activation energy are caused by the\nformation of the small-polarons localized in the O-Cr-O lattice distortion. The\norigin of small-polarons in the undoped sample is different in nature from the\ncalcium doped. \"Local non-centrosymetry\" is the source of the small-polaron\nformation in undoped sample, while the change from Cr(III) to Cr(IV) through\nthe charge compensation of Ca(II) in the Y(III) site is the source of\nsmall-polarons formations. The decrease of the average bond length Cr-O as well\nas effective moments in the paramagnetic state and the increase of the\nelectrical conductivity are clear evidence that the Ca doping induces localized\npolarons, which in turn, these quasiparticles move from site to site by a\nthermally activated process in the doped YCrO3 compound. Here, we also discuss\na possible mechanism of small-polaron injections in YCrO3 matrix."
    },
    {
        "anchor": "Sigma-phase in the Fe-Re alloy system: experimental and theoretical\n  studies: X-ray diffraction (XRD) and M\\\"ossbauer spectroscopy techniques combined with\ntheoretical calculations based on the Korringa-Kohn-Rostoker (KKR) electronic\nstructure calculation method were used to investigate \\sigma-phase\nFe_{100-x}Re_{x} alloys (x = 43, 45, 47, 49 and 53). Structural data such as\nsite occupancies and lattice constants were derived from the XRD patters, while\nthe average isomer shift and distribution curves of the quadrupole splitting\nwere obtained from the M\\\"ossbauer spectra. Fe-site charge-densities and the\nquadrupole splittings were computed with the KKR method for each lattice site.\nThe calculated quantities combined with the experimentally determined site\noccupancies were successfully used to decompose the measured M\\\"ossbauer\nspectra into five components corresponding to the five sublattices.",
        "positive": "Lattice dynamics and coupled quadrupole-phonon excitations in CeAuAl$_3$: We report first principles calculations of the structural parameters and\nphonon dispersion of the tetragonal non-centrosymmetric heavy fermion compound\nCeAuAl$_3$. Taking into account weak magnetoelastic interactions of the\nrare-earth (RE) ions with the spectrum of phonons, we obtain an analytical\nexpression for the hybridization of quadrupole excitations and phonons from the\npoles of the one-phonon Green-function. In the paramagnetic phase, we predict\nthe formation of mixed modes that may be observed by inelastic neutron\nscattering. Our results show that magnetoelastic interactions, albeit being\nmoderate, play an important role in CeAuAl$_3$. This suggests that\nmagnetoelastic interactions may be equally important in a wide range of related\ncompounds."
    },
    {
        "anchor": "A Parameter Free Double Shear Theory for Lath Martensite: A double shear theory is introduced that predicts the commonly observed {5 5\n7} habit planes in low-carbon steels. The novelty of this theory is that no\nparameter fitting is necessary. Instead, the shearing systems are chosen in\nanalogy to the original (single shear) phenomenological theory of martensite\ncrystallography as those that are macroscopically equivalent to twinning. Out\nof all the resulting double shear theories, the ones leading to certain {h h k}\nhabit planes naturally arise as those having small shape strain magnitude and\nsatisfying a condition of maximal compatibility, thus making any parameter\nfitting unnecessary. An interesting finding is that the precise coordinates of\nthe predicted {h h k} habit planes depend sensitively on the lattice parameters\nof the fcc (face-centered cubic) and bcc (body-centered cubic) phases.\nNonetheless, for various realistic lattice parameters in low carbon steels, the\npredicted habit planes are near {5 5 7}. The examples of Fe-0.252C and Fe-0.6C\nare analyzed in detail along with the resulting orientation relationships which\nare consistently close to the Kurdjumov-Sachs model. Furthermore, a MATLAB app\n(available at github.com/AntonMu/LathApp) is provided which allows the\napplication of this model to any other material undergoing an fcc to bcc\ntransformation.",
        "positive": "Anharmonic and Quantum Fluctuations in Molecular Crystals: A\n  First-Principles Study of the Stability of Paracetamol: Molecular crystals often exist in multiple competing polymorphs, showing\nsignificantly different physico-chemical properties. Computational crystal\nstructure prediction is key to interpret and guide the search for the most\nstable or useful form: A real challenge due to the combinatorial search space,\nand the complex interplay of subtle effects that work together to determine the\nrelative stability of different structures. Here we take a comprehensive\napproach based on different flavors of thermodynamic integration in order to\nestimate all contributions to the free energies of these systems with\ndensity-functional theory, including the oft-neglected anharmonic contributions\nand nuclear quantum effects. We take the two main stable forms of paracetamol\nas a paradigmatic example. We find that anharmonic contributions, different\ndescriptions of van der Waals interactions, and nuclear quantum effects all\nmatter to quantitatively determine the stability of different phases. Our\nanalysis highlights the many challenges inherent in the development of a\nquantitative and predictive framework to model molecular crystals. However, it\nalso indicates which of the components of the free energy can benefit from a\ncancellation of errors that can redeem the predictive power of approximate\nmodels, and suggests simple steps that could be taken to improve the\nreliability of ab initio crystal structure prediction."
    },
    {
        "anchor": "Missed ferroelectricity in methylammonium lead iodide: Methylammonium lead iodide, as related organometal halide perovskites,\nemerged recently as a particularly attractive material for photovoltaic\napplications. The origin of its appealing properties is sometimes assigned to\nits potential ferroelectric character, which remains however a topic of intense\ndebate. Here, we rationalize from first-principles calculations how the spatial\narrangement of methylammonium polar molecules is progressively constrained by\nthe subtle interplay between their tendency to bond with the inorganic\nframework and the appearance of iodine octahedra rotations inherent to the\nperovskite structure. The disordered tetragonal phase observed at room\ntemperature is paraelectric. We show that it should a priori become\nferroelectric but that iodine octahedra rotations drive the system toward an\nantipolar orthorhombic ground state, making it a missed ferroelectric.",
        "positive": "Effect of heat treatment on the structural and microstructural\n  properties of the Co2-Y hexaferrites: The effect of heat treatment on the structural and micro-structural\nproperties of the Co2-Y (Ba2Co2Fe12O22) was investigated by means of X-ray\ndiffraction and the Rietveld refinement. The samples were synthesized using\nhigh-energy ball milling technique. Phase identification and Rietveld\nrefinement of the samples confirmed the presence of a single Y-type phase that\nis consistent with reported patterns. Analysis of the lattice constants\nobtained using the Rietveld refinement confirmed the presence of inner\ndistortion, which was responsible for increasing the lattice constants.\nHowever, after the heat treatment, the lattice constants were in good agreement\nwith the reported pattern. The structural analysis using quadratic elongation\nrevealed distortions in the crystal structure. The structural analysis revealed\nsome differences in the cation-anion distances in some sites, while in other\nsites, these distances remained the same. The use of the Rietveld refinement to\nobtain micro-structural information about the size and the strain was reported.\nHeat treatment induced diffusion between crystal domains leading to an increase\nin crystallite size."
    },
    {
        "anchor": "One-particle and excitonic band structure in cubic Boron Arsenide: Cubic BAs has received recent attention for its large electron and hole\nmobilities and large thermal conductivity. This is a rare and much desired\ncombination in semiconductor industry: commercial semiconductors typically have\nhigh electron mobilities, or hole mobilities, or large thermal conductivities,\nbut not all of them together. Here we report predictions from an advanced\nself-consistent many body perturbative theory and show that with respect to\none-particle properties, BAs is strikingly similar to Si. There are some\nimportant differences, notably there is an unusually small variation in the\nvalence band masses . With respect to two-particle properties, significant\ndifferences with Si appear. We report the excitonic spectrum for both q=0 and\nfinite q, and show that while the direct gap in cubic BAs is about 4 eV, dark\nexcitons can be observed down to about $\\sim$1.5 eV, which may play a crucial\nrole in application of BAs in optoelectronics.",
        "positive": "Pseudoepitaxial transrotational structures in 14 nm-thick NiSi layers on\n  [001] silicon: In a system consisting of two different lattices, the structural stability is\nensured when an epitaxial relationship occurs between them and allows the\nsystem to retain the stress, avoiding the formation of a polycristalline film.\nThe phenomenon occurs if the film thickness does not exceed a critical value.\nHere we show that, in spite of its orthorombic structure, a 14nm-thick NiSi\nlayer can three-dimensionally (3D) adapt to the cubic Si lattice by forming\ntransrotational domains. Each domain arises by the continuous bending of the\nNiSi lattice, maintaining a close relationship with the substrate structure.\nThe presence of transrotational domains does not cause a roughening of the\nlayer but instead it improves the structural and electrical stability of the\nsilicide in comparison with a 24nm-thick layer formed using the same annealing\nprocess. These results have relevant implications on thickness scaling of NiSi\nlayers currently used as metallizations of electronic devices."
    },
    {
        "anchor": "Quadrupole Arrangements and the Ground State of Solid Hydrogen: The electric quadrupole-quadrupole ($\\mathcal{E}_{qq}$) interaction is\nbelieved to play an important role in the broken symmetry transition from Phase\nI to II in solid hydrogen. To evaluate this, we study structures adopted by\npurely classical quadrupoles using Markov Chain Monte Carlo simulations of fcc\nand hcp quadrupolar lattices. Both undergo first-order phase transitions from\nrotationally ordered to disordered structures, as indicated by a discontinuity\nin both quadrupole interaction energy ($\\mathcal{E}_{qq}$) and its heat\ncapacity. Cooling fcc reliably induced a transition to the P$a3$ structure,\nwhereas cooling hcp gave inconsistent, frustrated and $c/a$-ratio-dependent\nbroken symmetry states. Analysing the lowest-energy hcp states using simulated\nannealing, we found P$6_3/m$ and P$ca2_1$ structures found previously as\nminimum-energy structures in full electronic structure calculations. The\ncandidate structures for hydrogen Phases III-V were not observed. This\ndemonstrates that $\\mathcal{E}_{qq}$ is the dominant interaction determining\nthe symmetry breaking in Phase II. The disorder transition occurs at\nsignificantly lower temperature in hcp than fcc, showing that the\n$\\mathcal{E}_{qq}$ cannot be responsible for hydrogen Phase II being based on\nhcp.",
        "positive": "Optimization strategies developed on NiO for Heisenberg exchange\n  coupling calculations using projector augmented wave based first-principles\n  DFT+U+J: High-performance batteries, heterogeneous catalysts and next-generation\nphotovoltaics often centrally involve transition metal oxides (TMOs) that\nundergo charge or spin-state changes. Demand for accurate DFT modeling of TMOs\nhas increased in recent years, driving improved quantification and correction\nschemes for approximate DFT's characteristic errors, notably those pertaining\nto self-interaction and static correlation. Of considerable interest,\nmeanwhile, is the use of DFT-accessible quantities to compute parameters of\ncoarse-grained models such as for magnetism. To understand the interference of\nerror corrections and model mappings, we probe the prototypical Mott-Hubbard\ninsulator NiO, calculating its electronic structure in its antiferromagnetic\nI/II and ferromagnetic states. We examine the pronounced sensitivity of the\nfirst principles calculated Hubbard U and Hund's J parameters to choices\nconcerning Projector Augmented Wave (PAW) based population analysis, we\nreevaluate spin quantification conventions for the Heisenberg model, and we\nseek to develop best practices for calculating Hubbard parameters specific to\nenergetically meta-stable magnetic orderings of TMOs. Within this framework, we\nassess several corrective functionals using in situ calculated U and J\nparameters, e.g., DFT+U and DFT+U+J. We find that while using a straightforward\nworkflow with minimal empiricism, the NiO Heisenberg parameter RMS error with\nrespect to experiment was reduced to 13%, an advance upon the state-of-the-art.\nMethodologically, we used a linear-response implementation for calculating the\nHubbard U available in the open-source plane-wave DFT code Abinit. We have\nextended its utility to calculate the Hund's exchange coupling J, however our\nfindings are anticipated to be applicable to any DFT+U implementation."
    },
    {
        "anchor": "Crystal-symmetry-based selection rules for anharmonic phonon-phonon\n  scattering from a group theory formalism: Anharmonic phonon-phonon scattering serves a critical role in heat conduction\nin solids. Previous studies have identified many selection rules for possible\nphonon-phonon scattering channels imposed by phonon energy and momentum\nconservation conditions and crystal symmetry. However, the\ncrystal-symmetry-based selection rules have mostly been \\textit{ad hoc} so far\nin selected materials, and a general formalism that can summarize known\nselection rules and lead to new ones in any given crystal is still lacking. In\nthis work, we apply a general formalism for symmetry-based scattering selection\nrules based on the group theory to anharmonic phonon-phonon scatterings, which\ncan reproduce known selection rules and guide the discovery of new selection\nrules between phonon branches imposed by the crystal symmetry. We apply this\nformalism to analyze the phonon-phonon scattering selection rules imposed by\nthe in-plane symmetry of graphene, and demonstrate the significant impact of\nsymmetry-breaking strain on the lattice thermal conductivity. Our work\nquantifies the critical influence of the crystal symmetry on the lattice\nthermal conductivity in solids and suggests routes to engineer heat conduction\nby tuning the crystal symmetry.",
        "positive": "Micromagnetic modelling of nanorods array-based L10-FeNi/SmCo5\n  exchange-coupled composites: Exchange-coupled nanocomposites are considered as the most promising\nmaterials for production of high-energy performance permanent magnets, which\ncan exceed neodymium ones in terms of energy product. In this work,\nmicromagnetic simulations of L10-FeNi/SmCo5 composites based on the initially\nanisotropic structure of nanorods array were performed. Texturing effect on\nmagnetic properties was investigated. It was revealed that even 30 % of\nanisotropy axes misalignment of grains in L10-FeNi phase would lead to only 10\n% drop of coercivity. To maximize magnetic properties of the composites,\nparameters of microstructure were optimized for 120 x 120 array of interacting\nnanorods and were found to be 40 nm nanorod diameter and 12-20 nm interrod\ndistance. The estimated diameter of nanorods and the packing density of the\narray provide energy product values of 149 kJ m-3. Influence of interrod\ndistance on energy product values was explored. Approaches for production of\nexchange-coupled composites based on anisotropic nanostructures were proposed."
    },
    {
        "anchor": "Temperature dependence of nonlinear auto-oscillator linewidths:\n  Application to spin-torque nano-oscillators: The temperature dependence of the generation linewidth for an auto-oscillator\nwith a nonlinear frequency shift is calculated. It is shown that the frequency\nnonlinearity creates a finite correlation time, tau, for the phase\nfluctuations. In the low-temperature limit in which the spectral linewidth is\nsmaller than 1/tau, the line shape is approximately Lorentzian and the\nlinewidth is linear in temperature. In the opposite high-temperature limit in\nwhich the linewidth is larger than 1/tau, the nonlinearity leads to an apparent\n\"inhomogeneous broadening\" of the line, which becomes Gaussian in shape and has\na square-root dependence on temperature. The results are illustrated for the\nspin-torque nano-oscillator.",
        "positive": "Unravelling the role of the interface for spin injection into organic\n  semiconductors: Whereas spintronics brings the spin degree of freedom to electronic devices,\nmolecular/organic electronics adds the opportunity to play with the chemical\nversatility. Here we show how, as a contender to commonly used inorganic\nmaterials, organic/molecular based spintronics devices can exhibit very large\nmagnetoresistance and lead to tailored spin polarizations. We report on giant\ntunnel magnetoresistance of up to 300% in a (La,Sr)MnO3/Alq3/Co nanometer size\nmagnetic tunnel junction. Moreover, we propose a spin dependent transport model\ngiving a new understanding of spin injection into organic materials/molecules.\nOur findings bring a new insight on how one could tune spin injection by\nmolecular engineering and paves the way to chemical tailoring of the properties\nof spintronics devices."
    },
    {
        "anchor": "Influence of halide composition on the structural, electronic, and\n  optical properties of mixed CH$_3$NH$_3$Pb(I$_{1-x}$Br$_x$)$_3$ perovskites\n  calculated using the virtual crystal approximation method: We investigate the structural, electronic and optical properties of mixed\nbromide-iodide lead perovskite solar cell CH$_3$NH$_3$Pb(I$_{1-x}$Br$_x$)$_3$\nby means of the virtual crystal approximation (VCA) within density functional\ntheory (DFT). Optimizing the atomic positions and lattice parameters increasing\nthe bromide content $x$ from 0.0 to 1.0, we fit the calculated lattice\nparameter and energy band gap to the linear and quadratic function of Br\ncontent, respectively, which are in good agreement with the experiment,\nrespecting the Vegard's law. With the calculated exciton binding energy and\nlight absorption coefficient, we make sure that VCA gives consistent results\nwith the experiment, and the mixed halide perovskites are suitable for\ngenerating the charge carriers by light absorption and conducting the carriers\neasily due to their strong photon absorption coefficient, low exciton bindign\nenergy, and high carrier mobility at low Br contents. Furthermore analyzing the\nbonding lengths between Pb and X (I$_{1-x}$Br$_x$: virtual atom) as well as C\nand N, we stress that the stability of perovskite solar cell is definitely\nimproved at $x$=0.2.",
        "positive": "Charge Inversion of Divalent Ionic Solutions in Silica Channels: Recent experiments (F.H.J. Van Der Heyden et al., PRL 96, 224502 (2006)) of\nstreaming currents in silica nanochannels with divalent ions report charge\ninversion, i.e. interfacial charges attracting counterions in excess of their\nown nominal charge, in conflict with existing theoretical and simulation\nresults. We reveal the mechanism of charge inversion by using all-atomic\nmolecular dynamics simulations. Our results show excellent agreement with\nexperiments, both qualitatively and quantitatively. We further discuss the\nimplications of our study for the general problem of ionic correlations in\nsolutions as well as in regards of the properties of silica-water interfaces."
    },
    {
        "anchor": "Description of a specialized stress equipment for EPR X-band\n  measurements: A specialized stress equipment has been developed for EPR X-band experiments.\nUniaxial stress experiments in EPR of different impurity ions in SrTiO3 and\nBaTiO3 will be reviewed.",
        "positive": "Biaxial Strain in the Hexagonal Plane of MnAs Thin Films: The Key to\n  Stabilize Ferromagnetism to Higher Temperature: The alpha-beta magneto-structural phase transition in MnAs/GaAs(111)\nepilayers is investigated by elastic neutron scattering. The in-plane parameter\nof MnAs remains almost constant with temperature from 100 K to 420 K, following\nthe thermal evolution of the GaAs substrate. This induces a temperature\ndependent biaxial strain that is responsible for an alpha-beta phase\ncoexistence and, more important, for the stabilization of the ferromagnetic\nalpha-phase at higher temperature than in bulk. We explain the premature\nappearance of the beta-phase at 275 K and the persistence of the ferromagnetic\nalpha-phase up to 350 K with thermodynamical arguments based on the MnAs phase\ndiagram. It results that the biaxial strain in the hexagonal plane is the key\nparameter to extend the ferromagnetic phase well over room temperature."
    },
    {
        "anchor": "Effect of 200 MeV Ag15+ ion irradiation on structural and electrical\n  transport properties of Fe3O4 thin films: Thin films of Fe3O4 have been deposited on single crystal MgO (100) and Si\n(100) substrates using pulsed laser deposition. Films grown on MgO substrate\nare epitaxial with c-axis orientation whereas, films on Si substrate are highly\n<111> oriented. Film thicknesses are 150 nm. These films have been irradiated\nwith 200 MeV Ag ions. We study the effect of the irradiation on structural and\nelectrical transport properties of these films. The fluence value of\nirradiation has been varied in the range of 5 x 1010 ions/cm2 to1 x 1012\nions/cm2. We compare the irradiation induced modifications on various physical\nproperties between the c-axis oriented epitaxial film and non epitaxial but\n<111> oriented film. The pristine film on Si substrate shows Verwey transition\n(TV) close to 125 K, which is higher than generally observed in single crystals\n(121 K). After the irradiation with the 5 x 1010 ions/cm2 fluence value, TV\nshifts to 122 K, closer to the single crystal value. However, with the higher\nfluence (1 x 1012 ions/cm2) irradiation, TV again shifts to 125 K.",
        "positive": "The origin of grain size effects in Ba(Ti0.96Sn0.04)O3 perovskite\n  ceramics with superior electrical properties: The study of grain size effects in ferroelectric ceramics has attracted great\nresearch interest over the last 50 years. Although different theoretical models\nhave been proposed to account for the variation in structure and properties\nwith grain size, the underlying mechanisms are still under debate, creating a\nsignificant level of uncertainty in the field. Here, we report the results of a\nstudy on the influence of grain size on the structural and physical properties\nof Ba(Ti0.96Sn0.04)O3, which represents a model perovskite system, where the\neffects of point defects, stoichiometry imbalance and phase transitions are\nminimized by Sn substitution. It was found that different microscopic\nmechanisms are responsible for the various grain size dependences observed. In\nfine-grained ceramics, high permittivity is due to high domain wall density and\npolar nanoregions; high d33 in coarse-grained ceramics results from a high\ndegree of domain alignment during poling; large electric field-induced strain\nin intermediate-grained ceramics is an outcome of a favourable interplay\nbetween constraints from grain boundaries and reversible reorientation of\nnon-180 degree domains and polar nanoregions. These paradigms can be regarded\nas general guidelines for the optimization of specific properties through grain\nsize control."
    },
    {
        "anchor": "Dislocation dynamics and crystal plasticity in the phase field crystal\n  model: A phase field model of a crystalline material at the mesoscale is introduced\nto develop the necessary theoretical framework to study plastic flow due to\ndislocation motion. We first obtain the elastic stress from the phase field\nfree energy and show that it obeys the stress strain relation of linear\nelasticity. Dislocations in a two dimensional hexagonal lattice are shown to be\ncomposite topological defects in the amplitude expansion of the phase field,\nwith topological charges given by the Burgers vector. This allows us to\nintroduce a formal relation between dislocation velocity and the evolution of\nthe coarse grained envelopes of the phase field. Standard dissipative dynamics\nof the phase field crystal model is shown to determine the velocity of the\ndislocations. When the amplitude equation is valid, we derive the Peach-Koehler\nforce on a dislocation, and compute the associated defect mobility. A numerical\nintegration of the phase field crystal equations in two dimensions is used to\ncompute the motion of a dislocation dipole, and good agreement is found with\nthe theoretical predictions.",
        "positive": "Optical Signatures of Dirac Nodal-lines in NbAs$_2$: Using polarized optical and magneto-optical spectroscopy, we have\ndemonstrated universal aspects of electrodynamics associated with Dirac\nnodal-lines. We investigated anisotropic electrodynamics of NbAs$_2$ where the\nspin-orbit interaction triggers energy gaps along the nodal-lines, which\nmanifest as sharp steps in the optical conductivity spectra. We show\nexperimentally and theoretically that shifted 2D Dirac nodal-lines feature\nlinear scaling $\\sigma_1 (\\omega)\\sim\\omega$, similar to 3D nodal-points.\nMassive Dirac nature of the nodal-lines are confirmed by magneto-optical data,\nwhich may also be indicative of theoretically predicted surface states. Optical\ndata also offer a natural explanation for the giant magneto-resistance in\nNbAs$_2$."
    },
    {
        "anchor": "Competing Exchange Interactions in the Multiferroic and Ferrimagnetic\n  CaBaCo$_4$O$_7$: Competing exchange interactions can produce complex magnetic states together\nwith spin-induced electric polarizations. With competing interactions on\nalternating triangular and kagome layers, the swedenborgite CBO may have one of\nthe largest measured spin-induced polarizations of about 1700 nC/cm$^2$ below\nits ferrimagnetic transition temperature at 70 K. Powder neutron-diffraction\ndata, magnetization measurements, and spin-wave resonance frequencies in the\nTHz range reveal that the complex spin order of multiferroic CBO can be\ndescribed as a triangular array of c-axis chains ferrimagnetically coupled to\neach other in the ab plane. Magnetostriction on bonds that couple those chains\nproduces the large spin-induced polarization of CBO.",
        "positive": "Kinetics of helium bubble formation in nuclear materials: The formation and growth of helium bubbles due to self-irradiation in\nplutonium has been modelled by a discrete kinetic equations for the number\ndensities of bubbles having $k$ atoms. Analysis of these equations shows that\nthe bubble size distribution function can be approximated by a composite of:\n(i) the solution of partial differential equations describing the continuum\nlimit of the theory but corrected to take into account the effects of\ndiscreteness, and (ii) a local expansion about the advancing leading edge of\nthe distribution function in size space. Both approximations contribute to the\nmemory term in a close integrodifferential equation for the monomer\nconcentration of single helium atoms.\n  The present boundary layer theory for discrete equations is compared to the\nnumerical solution of the full kinetic model and to previous approximation of\nSchaldach and Wolfer involving a truncated system of moment equations."
    },
    {
        "anchor": "Isotoxal star-shaped polygonal voids and rigid inclusions in nonuniform\n  antiplane shear fields. Part II: Singularities, annihilation and invisibility: Notch stress intensity factors and stress intensity factors are obtained\nanalytically for isotoxal star-shaped polygonal voids and rigid inclusions (and\nalso for the corresponding limit cases of star-shaped cracks and stiffeners),\nwhen loaded through remote inhomogeneous (self-equilibrated, polynomial)\nantiplane shear stress in an infinite linear elastic matrix. Usually these\nsolutions show stress singularities at the inclusion corners. It is shown that\nan infinite set of geometries and loading conditions exist for which not only\nthe singularity is absent, but the stress vanishes ('annihilates') at the\ncorners. Thus the material, which even without the inclusion corners would have\na finite stress, remains unstressed at these points in spite of the applied\nremote load. Moreover, similar conditions are determined in which a star-shaped\ncrack or stiffener leaves the ambient stress completely unperturbed, thus\nreaching a condition of 'quasi-static invisibility'. Stress annihilation and\ninvisibility define optimal loading modes for the overall strength of a\ncomposite and are useful for designing ultra-resistant materials.",
        "positive": "Image analysis as an improved melting criterion in laser-heated diamond\n  anvil cell: The precision of melting curve measurements using laser-heated diamond anvil\ncell (LHDAC) is largely limited by the correct and reliable determination of\nthe onset of melting. We present a novel image analysis of speckle interference\npatterns in the LHDAC as a way to define quantitative measures which enable an\nobjective determination of the melting transition. Combined with our\nlow-temperature customized IR pyrometer, designed for measurements down to\n500K, our setup allows studying the melting curve of materials with low melting\ntemperatures, with relatively high precision. As an application, the melting\ncurve of Te was measured up to~$\\rm35\\,GPa$. The results are found to be in\ngood agreement with previous data obtained at pressures up to~$\\rm10\\,GPa$."
    },
    {
        "anchor": "Critical current density for spin transfer torque switching with\n  composite free layer structure: Critical current density of composite free layer (CFL) in magnetic tunneling\njunction is investigated. CFL consists of two exchange coupled ferromagnetic\nlayers, where the coupling is parallel or anti-parallel. Instability condition\nof the CFL under the spin transfer torque, which is related with critical\ncurrent density, is obtained by analytic spin wave excitation model and\nconfirmed by macro-spin Landau-Lifshitz-Gilbert equation. The critical current\ndensities for the coupled two identical layers are investigated with various\ncoupling strengths, and spin transfer torque efficiencies.",
        "positive": "First-principles predictions of low-energy phases of multiferroic BiFeO3: We used first-principles methods to perform a systematic search for\npotentially-stable phases of multiferroic BiFeO3. We considered a simulation\ncell compatible with the atomic distortions that are most common among\nperovskite oxides, and found a large number of local minima of the energy\nwithin 100 meV/f.u. of the ferroelectric ground state. We discuss the variety\nof low-symmetry structures discovered, as well as the implications of these\nfindings as regards current experimental (e.g., on thin films displaying {\\em\nsuper-tetragonal} phases) and theoretical (on models for BiFeO3's structural\nphase transitions) work on this compound."
    },
    {
        "anchor": "Light-weight sodium alanate thin films grown by reactive sputtering: We report the preparation of sodium alanate, a promising hydrogen storage\nmaterial, in a thin film form using co-sputtering in a reactive atmosphere of\natomic hydrogen. We study the phase formation and distribution, and the\nhydrogen desorption, with a combination of optical and infrared transmission\nspectroscopy. We show that the hydrogen desorption, the phase segregation and\nthe role of the dopants in these complex metal hydrides can be monitored with\noptical measurements. This result shows that a thin film approach can be used\nfor a model study of technologically relevant lightweight metal hydrides.",
        "positive": "Manipulation of ferroelectric and magnetic properties properties of\n  single phase Bi4Ti3O12-3BiFeO3 solid solution through La substitution: In this work, the potential to exploit Aurivillius higher order composition\n(n=6) given by Bi4Ti3O12-3BiFeO3 as single phase and high temperature\nmagnetoelectric materials are well explored by elaborately studying the\nconcerned structure and physical properties. Bi4Ti3O12-3Bi1-xLaxFeO3 (x=0,\n0.01, 0.05, 0.1, 0.2) was synthesized via solid-state reaction route and X-ray\ndiffraction data revealed that the lattice parameters associated with\northorhombic cell (space group P21am) decrease with increase in La3+ content\nconfirming the incorporation of La. In the frequency dependent dielectric\nmeasurements, the ferroelectric to paraelectric transition temperature (Tc)\ncorresponding to the parent (x=0) had two phase transitions vis., 803 K\n(broader) and 983 K (sharper) whereas phase transitions are single that\nprogressively becomes sharper with increase in La substitution. Ferroelectric\nswitching behavior (polarization (P) versus electric field (E)) was\ndemonstrated for Bi4Ti3O12-3BiFeO3 and remnant polarization decreased\nsignificantly for La substituted compositions reflecting weaker ferroelectric\nordering. In detailed Zero Field-cooled and Field cooled temperature dependent\nmagnetization measurements, Bi4Ti3O12-3BiFeO3 exhibited Tc around 296 K. Though\na marginal increase in the magnetization values for La substituted compositions\n(x=0.1 and x=0.2), the overall temperature dependent magnetization curves\nindicate overall paramagnetic nature. The results are more reflective of the\nswitching off of the possibilities of long range ferromagnetic ordering with\nA-site rare earth doping in these Aurivillius layered compounds."
    },
    {
        "anchor": "Lattice instabilities in cubic pyrochlore Bi$_2$Ti$_2$O$_7$: The oxide pyrochlore Bi$_2$Ti$_2$O$_7$ is in some ways analogous to\nperovskite PbTiO$_3$, in that Bi$_2$Ti$_2$O$_7$ has two cations, Bi$^{3+}$ and\nTi$^{4+}$ in oxidation states that are normally associated with a propensity to\noff-center. However, unlike PbTiO$_3$, Bi$_2$Ti$_2$O$_7$ is experimentally\nobserved to remain cubic down to 2 K, while the only observed ionic\ndisplacements are local and incoherent. Here we report first-principles\ncalculations of the zone-center phonons of the ordered cubic pyrochlore which\nreveal several lattice instabilities. An analysis of the structural energetics\nsuggest that the ordered cubic pyrochlore is unstable with respect to\ndistortion towards a ferroelectric ground state with a large polarization. Our\nresults suggest a key role of a frustrated soft polar mode in the dielectric\nproperties of bismuth pyrochlores.",
        "positive": "ATK-ForceField: A New Generation Molecular Dynamics Software Package: ATK-ForceField is a software package for atomistic simulations using\nclassical interatomic potentials. It is implemented as a part of the Atomistix\nToolKit (ATK), which is a Python programming environment that makes it easy to\ncreate and analyze both standard and highly customized simulations. This paper\nwill focus on the atomic interaction potentials, molecular dynamics, and\ngeometry optimization features of the software, however, many more advanced\nmodeling features are available. The implementation details of these algorithms\nand their computational performance will be shown. We present three\nillustrative examples of the types of calculations that are possible with\nATK-ForceField: modeling thermal transport properties in a silicon germanium\ncrystal, vapor deposition of selenium molecules on a selenium surface, and a\nsimulation of creep in a copper polycrystal."
    },
    {
        "anchor": "Magneto-electroluminescence of organic heterostructures: Analytical\n  theory and spectrally resolved measurements: The effect of a magnetic field on the electroluminescence of organic light\nemitting devices originates from the hyperfine interaction between the\nelectron/hole polarons and the hydrogen nuclei of the host molecules. In this\npaper, we present an analytical theory of magneto-electroluminescence for\norganic semiconductors. To be specific, we focus on bilayer heterostructure\ndevices. In the case we are considering, light generation at the interface of\nthe donor and acceptor layers results from the formation and recombination of\nexciplexes. The spin physics is described by a stochastic Liouville equation\nfor the electron/hole spin density matrix. By finding the steady-state\nanalytical solution using Bloch-Wangsness-Redfield theory, we explore how the\nsinglet/triplet exciplex ratio is affected by the hyperfine interaction\nstrength and by the external magnetic field. To validate the theory,\nspectrally-resolved electroluminescence experiments on BPhen/m-MTDATA devices\nare analyzed. With increasing emission wavelength, the width of the magnetic\nfield modulation curve of the electroluminescence increases while its depth\ndecreases. These observations are consistent with the model. Finally, the\nanalytical theory is extended to account for an additional low-field structure\ndue to the exchange interaction in the weakly bound polaron-pair states.",
        "positive": "Explicit treatment of hydrogen bonds in the Universal Force Field:\n  validation and application for Metal-Organic Frameworks, hydrates and\n  host-guest complexes: A straightforward means to include explicit hydrogen bonds within the\nUniversal Force Field is presented. Instead of treating hydrogen bonds as\nnon-bonded interaction subjected to electrostatic and Lennard-Jones potentials,\nwe introduce an explicit bond with negligible bond order, thus maintaining the\nstructural integrity of the H-bonded complexes and avoiding the necessity to\nassign arbitrary charges to the system. The explicit hydrogen bond changes the\ncoordination number of the acceptor site and the approach is thus most suitable\nfor systems with under-coordinated atoms, such as many metal-organic\nframeworks, however, it also shows excellent performance for other systems\ninvolving a hydrogen-bonded framework. In particular, it is an excellent means\nfor creating starting structures for molecular dynamics and for investigations\nemploying more sophisticated methods.\n  The approach is validated for the hydrogen bonded complexes in the S22\ndataset and then employed for a set of metal-organic frameworks from the\nComputation-Ready Experimental (CoRE) database and several hydrogen bonded\ncrystals including water ice and clathrates. We show that direct inclusion of\nhydrogen bonds reduces the maximum error in predicted cell parameters from 66%\nto only 14% and the mean unsigned error is similarly reduced from 14% to only\n4%. We posit that with the inclusion of hydrogen bonding, the solvent-mediated\nbreathing of frameworks such as MIL-53 is now accessible to rapid UFF\ncalculations, which will further the aim of rapid computational scanning of\nmetal-organic frameworks while providing better starting points for electronic\nstructure calculations."
    },
    {
        "anchor": "Giant spin Hall Effect in two-dimensional monochalcogenides: One of the most exciting properties of two dimensional materials is their\nsensitivity to external tuning of the electronic properties, for example via\nelectric field or strain. Recently discovered analogues of phosphorene,\ngroup-IV monochalcogenides (MX with M = Ge, Sn and X = S, Se, Te), display\nseveral interesting phenomena intimately related to the in-plane strain, such\nas giant piezoelectricity and multiferroicity, which combine ferroelastic and\nferroelectric properties. Here, using calculations from first principles, we\nreveal for the first time giant intrinsic spin Hall conductivities (SHC) in\nthese materials. In particular, we show that the SHC resonances can be easily\ntuned by combination of strain and doping and, in some cases, strain can be\nused to induce semiconductor to metal transitions that make a giant spin Hall\neffect possible even in absence of doping. Our results indicate a new route for\nthe design of highly tunable spintronics devices based on two-dimensional\nmaterials.",
        "positive": "Highly Anisotropic Electronic and Mechanical Properties of Monolayer and\n  Bilayer As2S3: Anisotropic materials, with orientation-dependent properties, have attracted\nmore and more attention due to their compelling tunable and flexible\nperformance in electronic and optomechanical devices. So far, two-dimensional\n(2D) black phosphorus shows the largest known anisotropic behavior, which is\nhighly desired for synaptic and neuromorphic devices, multifunctional\ndirectional memories, and even polarization-sensitive photodetector, whereas it\nis unstable at ambient conditions. Recently, 2D few-layered As2S3 with superior\nchemical stability was successfully exfoliated in experiments. However, the\nelectronic and mechanical properties of monolayer and bilayer As2S3 is still\nlacking. Here, we report the large anisotropic electronic and mechanical\nproperties of As2S3 systems through first-principles calculations and general\nangle-dependent Hooke's law. Monolayer and bilayer As2S3 exhibit anisotropic\nfactors of Young's modulus of 3.15 and 3.32, respectively, which are larger\nthan the black phosphorous with experimentally confirmed and an anisotropic\nfactor of 2. This study provides an effective route to flexible\norientation-dependent nanoelectronics, nanomechanics, and offers implications\nin promoting related experimental investigations."
    },
    {
        "anchor": "Polarization fields in GaN/AlN nanowire heterostructures studied by Off\n  axis holography: In this work, we present an off-axis holography study of GaN/AlN\nheterostructured nanowires grown by plasma-assisted molecular-beam epitaxy. We\ndiscuss the sample preparation of nanowire samples for electron holography and\ncombine potential profiles obtained using holography with theoretical\ncalculations of the projected potential in order to gain understanding of the\npotential distribution in these nanostructures. The effects of surface states\nare discussed",
        "positive": "Composition based oxidation state prediction of materials using deep\n  learning: Oxidation states are the charges of atoms after their ionic approximation of\ntheir bonds, which have been widely used in charge-neutrality verification,\ncrystal structure determination, and reaction estimation. Currently only\nheuristic rules exist for guessing the oxidation states of a given compound\nwith many exceptions. Recent work has developed machine learning models based\non heuristic structural features for predicting the oxidation states of metal\nions. However, composition based oxidation state prediction still remains\nelusive so far, which is more important in new material discovery for which the\nstructures are not even available. This work proposes a novel deep learning\nbased BERT transformer language model BERTOS for predicting the oxidation\nstates of all elements of inorganic compounds given only their chemical\ncomposition. Our model achieves 96.82\\% accuracy for all-element oxidation\nstates prediction benchmarked on the cleaned ICSD dataset and achieves 97.61\\%\naccuracy for oxide materials. We also demonstrate how it can be used to conduct\nlarge-scale screening of hypothetical material compositions for materials\ndiscovery."
    },
    {
        "anchor": "Quantitative characterization of pore structure of several biochars with\n  3D imaging: Pore space characteristics of biochars may vary depending on the used raw\nmaterial and processing technology. Pore structure has significant effects on\nthe water retention properties of biochar amended soils. In this work, several\nbiochars were characterized with three-dimensional imaging and image analysis.\nX-ray computed microtomography was used to image biochars at resolution of 1.14\n$\\mu$m and the obtained images were analysed for porosity, pore-size\ndistribution, specific surface area and structural anisotropy. In addition,\nrandom walk simulations were used to relate structural anisotropy to diffusive\ntransport. Image analysis showed that considerable part of the biochar volume\nconsist of pores in size range relevant to hydrological processes and storage\nof plant available water. Porosity and pore-size distribution were found to\ndepend on the biochar type and the structural anisotopy analysis showed that\nused raw material considerably affects the pore characteristics at micrometre\nscale. Therefore attention should be paid to raw material selection and quality\nin applications requiring optimized pore structure.",
        "positive": "Surface growth for molten silicon infiltration into carbon\n  millimeter-sized channels: Lattice-Boltzmann simulations, experiments and\n  models: The process of liquid silicon infiltration is investigated for channels with\nradii from $0.25$ to $0.75$ [mm] drilled in compact carbon preforms. The\nadvantage of this setup is that the study of the phenomenon results to be\nsimplified. For comparison purposes, attempts are made in order to work out a\nframework for evaluating the accuracy of simulations. The approach relies on\ndimensionless numbers involving the properties of the surface reaction. It\nturns out that complex hydrodynamic behavior derived from second Newton law can\nbe made consistent with Lattice-Boltzmann simulations. The experiments give\nclear evidence that the growth of silicon carbide proceeds in two different\nstages and basic mechanisms are highlighted. Lattice-Boltzmann simulations\nprove to be an effective tool for the description of the growing phase. Namely,\nessential experimental constraints can be implemented. As a result, the\nexisting models are useful to gain more insight on the process of reactive\ninfiltration into porous media in the first stage of penetration, i.e. up to\npore closure because of surface growth. A way allowing to implement the\nresistance from chemical reaction in Darcy law is also proposed."
    },
    {
        "anchor": "Folding Energetics in Thin-Film Diaphragms: We perform experiments on thin-film diaphragms to show that the folding\npatterns of anisotropically compressed diaphragms are strikingly different from\nthose of isotropically compressed ones. We then use a simple von Karman model\nto relate the overall features of these folding patterns to the underlying\nenergetics. We show that the differences between the isotropic and anisotropic\ncases can be traced back to fundamental changes in the energy structure of the\ndiaphragms. Finally, we point out that the energy structure of thin-film\ndiaphragms is similar to that of many other systems in physics and engineering,\ninto which our study may provide interesting insights.",
        "positive": "First-principles study of electronic structures and optical properties\n  of Cu, Ag, and Au-doped anatase TiO2: We perform first-principles calculations to investigate the band structure,\ndensity of states, optical absorption, and the imaginary part of dielectric\nfunction of Cu, Ag, and Au-doped anatase TiO2 in 72 atoms systems. The\nelectronic structure results show that the Cu incorporation can lead to the\nenhancement of d states near the uppermost of valence band, while the Ag and Au\ndoping cause some new electronic states in band gap of TiO2. Meanwhile, it is\nfound that the visible optical absorptions of Cu, Ag, and Au-doped TiO2, are\nobserved by analyzing the results of optical properties,.which locate in the\nregion of 400-1000 nm. The absorption band edges of Cu, Ag, and Au-doped TiO2\nshift to the long wavelength region compared with the pure TiO2. Furthermore,\naccording to the calculated results, we propose the optical transition\nmechanisms of Cu, Ag, and Au-doped TiO2, respectively. Our results show that\nthe visible light response of TiO2 can be modulated by substitutional doping of\nCu, Ag, and Au."
    },
    {
        "anchor": "First-principles investigation of the very large Perpendicular Magnetic\n  Anisotropy at Fe|MgO Interfaces: The perpendicular magnetic anisotropy (PMA) arising at the interface between\nferromagnetic transition metals and metallic oxides are investigated via\nfirst-principles calculations. In this work very large values of PMA up to 3\nerg/cm$^2$ at Fe$|$MgO interfaces are reported in agreement with recent\nexperiments. The origin of PMA is attributed to overlap between O-$p_z$ and\ntransition metal $d_{z^2}$ orbitals hybridized with $d_{xz(yz)}$ orbitals with\nstronger spin-orbit coupling induced splitting around the Fermi level for\nperpendicular magnetization orientation. Furthemore, it is shown that the PMA\nvalue weakens in case of over- or underoxidation when oxygen $p_z$ and\ntransition metal $d_{z^2}$ orbitals overlap is strongly affected by disorder,\nin agreement with experimental observations in magnetic tunnel junctions.",
        "positive": "Higher-Order Topological Crystalline Insulating Phase and Quantized\n  Hinge Charge in Topological Electride Apatite: In higher-order topological insulators, bulk and surface electronic states\nare gapped, while there appear gapless hinge states protected by spatial\nsymmetry. Here we show by ab initio calculations that the La apatite electride\nis a higher-order topological crystalline insulator. It is a one-dimensional\nelectride, in which the one-dimensional interstitial hollows along the $c$ axis\nsupport anionic electrons, and the electronic states in these one-dimensional\nchannels are well approximated by the one-dimensional Su-Schrieffer-Heeger\nmodel. When the crystal is cleaved into a hexagonal prism, the 120$^\\circ$\nhinges support gapless hinge states, with their filling quantized to be 2/3.\nThis quantization of the filling comes from a topological origin. We find that\nthe quantized value of the filling depends on the fundamental blocks that\nconstitute the crystal. The apatite consists of the triangular blocks, which is\ncrucial for giving nontrivial fractional charge at the hinge."
    },
    {
        "anchor": "Comprehensive scan for nonmagnetic Weyl semimetals with nonlinear\n  optical response: As the development of topological band theory, comprehensive databases about\ntime reversal and crystalline symmetries protected nonmagnetic topological\nmaterials were developed via first-principles calculations recently. However,\nowing to the low symmetry requirement of Weyl points, the symmetry-based\ntopological indicator cannot be applied to Weyl semimetals (WSMs). Hitherto,\nthe WSMs with Weyl points in arbitrary positions are still absent in the\nwell-known databases. In this work, we develop an efficient algorithm to search\nfor Weyl points automatically and establish a database of nonmagnetic WSMs with\nWeyl points near Fermi level based on the total experimental noncentrosymmetric\ncrystal structures in the Inorganic Crystal Structure Database (ICSD). Totally\n46 Weyl semimetals were discovered to have nearly clean Fermi surface and Weyl\npoints near Fermi level within 300 meV, and 9 of them are chiral structures\nwhich may host the quantized circular photogalvanic effect. In addition, the\nnonlinear optical response is studied and giant shift current is explored in\nthe end. Besides nonmagnetic WSMs, our powerful tools can also be used in the\ndiscovery of magnetic topological materials.",
        "positive": "ESPEI for efficient thermodynamic database development, modification,\n  and uncertainty quantification: application to Cu-Mg: The software package ESPEI has been developed for efficient evaluation of\nthermodynamic model parameters within the CALPHAD method. ESPEI uses a linear\nfitting strategy to parameterize Gibbs energy functions of single phases based\non their thermochemical data and refine the model parameters using phase\nequilibrium data through Bayesian optimization within a Markov Chain Monte\nCarlo machine learning approach. In this paper, the methodologies employed in\nESPEI are discussed in detail and demonstrated for the Cu-Mg system down to 0 K\nusing unary descriptions based on segmented regression. The model parameter\nuncertainties are quantified and propagated to the Gibbs energy functions."
    },
    {
        "anchor": "Probing laser-driven structure formation at extreme scales in space and\n  time: Irradiation of solid surfaces with high intensity, ultrashort laser pulses\ntriggers a variety of secondary processes that can lead to the formation of\ntransient and permanent structures over large range of length scales from mm\ndown to the nano-range. One of the most prominent examples are LIPSS - Laser\nInduced Periodic Surface Structures. While LIPSS have been a scientific\nevergreen for of almost 60 years, experimental methods that combine ultrafast\ntemporal with the required nm spatial resolution have become available only\nrecently with the advent of short pulse, short wavelength free electron lasers.\nHere we discuss the current status and future perspectives in this field by\nexploiting the unique possibilities of these 4th-generation light sources to\naddress by time-domain experimental techniques the fundamental LIPSS-question,\nnamely why and how laser-irradiation can initiate the transition of a \"chaotic\"\n(rough) surface from an aperiodic into a periodic structure.",
        "positive": "Machine Learning for High-entropy Alloys: Progress, Challenges and\n  Opportunities: High-entropy alloys (HEAs) have attracted extensive interest due to their\nexceptional mechanical properties and the vast compositional space for new\nHEAs. However, understanding their novel physical mechanisms and then using\nthese mechanisms to design new HEAs are confronted with their high-dimensional\nchemical complexity, which presents unique challenges to (i) the theoretical\nmodeling that needs accurate atomic interactions for atomistic simulations and\n(ii) constructing reliable macro-scale models for high-throughput screening of\nvast amounts of candidate alloys. Machine learning (ML) sheds light on these\nproblems with its capability to represent extremely complex relations. This\nreview highlights the success and promising future of utilizing ML to overcome\nthese challenges. We first introduce the basics of ML algorithms and\napplication scenarios. We then summarize the state-of-the-art ML models\ndescribing atomic interactions and atomistic simulations of thermodynamic and\nmechanical properties. Special attention is paid to phase predictions,\nplanar-defect calculations, and plastic deformation simulations. Next, we\nreview ML models for macro-scale properties, such as lattice structures, phase\nformations, and mechanical properties. Examples of machine-learned\nphase-formation rules and order parameters are used to illustrate the workflow.\nFinally, we discuss the remaining challenges and present an outlook of research\ndirections, including uncertainty quantification and ML-guided inverse\nmaterials design."
    },
    {
        "anchor": "Viable thermionic emission from graphene-covered metals: Thermionic emission from monolayer graphene grown on representative\ntransition metals, Ir and Ru, is characterized by low-energy electron\nmicroscopy (LEEM). Work functions were determined from the temperature\ndependence of the emission current and from the electron energy spectrum of\nemitted electrons. The high-temperature work function of the strongly\ninteracting system graphene/Ru(0001) is sufficiently low, 3.3 \\pm 0.1 eV, to\nhave technological potential for large-area emitters that are spatially\nuniform, efficient, and chemically inert. The thermionic work functions of the\nless strongly interacting system graphene/Ir(111) are over 1 eV larger and vary\nsubstantially (0.4 eV) between graphene orientations rotated by 30{\\deg}.",
        "positive": "Formation of Co nanoclusters in epitaxial Ti_{0.96} Co_{0.04} O_2 thin\n  films and their ferromagnetism: Anatase Ti0.96Co0.04O2 films were grown epitaxially on SrTiO3 (001)\nsubstrates by using plused laser deposition with in-situ reflection high-energy\nelectron diffraction. The oxygen partial pressure, PO2, during the growth was\nsystematically varied. As PO2 decreased, the growth behavior was changed from a\n2-dimensional layer-by-layer-like growth to a 3-dimensional island-like one,\nwhich resulted in an increase in the saturation magnetization. These structural\nand magnetic changes were explained in terms of the formation of cobalt\nclusters whose existence was proved by transmission-electron-microscopie\nstudies. Our work clearly indicates that the cobalt clustering will cause\nroom-temperature ferromagnetism in the Co-doped TiO2 films."
    },
    {
        "anchor": "Anisotropic magnetization and sign change of dynamic susceptibility in\n  Na0.85CoO2 single crystal: The DC and AC magnetic susceptibilities of Na0.85CoO2 single crystals were\nmeasured for the different crystal orientations of H//(ab)- and H//(c)-axis.\nThe DC-magnetic susceptibility for H//(c)-direction exhibited the\nantiferromagnetic transition at TN= 22 K. The thermal hysteresis between the\nzero-field-cooled (ZFC) and the field-cooled (FC) magnetization below TN and\nthe large frustration parameter indicated the spin frustration along the\n(c)-axis. For an applied magnetic field in H//(ab)-plane, the DC magnetic\nsusceptibility exhibited the logarithmic divergent behavior at low temperatures\n(T < 6.8 K). This could be understood by the impurity spin effect, dressed by\nthe spin fluctuation. From the AC magnetic susceptibility measurements, the\nreal part of the AC-susceptibility for H//(ab) exhibited the spin glass-like\nbehavior at low temperatures (T < 4 K). Remarkably, for an applied AC magnetic\nfield with H//(c)-axis, the sign of the AC magnetic susceptibility changed from\na positive to a negative value with increasing AC magnetic field frequency (f >\n3 kHz) at low temperatures (T > 7 K). We interpret the sign change of AC\nmagnetic susceptibility along the (c)-axis in terms of the sudden sign reversal\nof the phase difference from in-phase to out-of-phase response with an applied\nAC magnetic field in the AC-susceptibility phase space.",
        "positive": "Photoluminescence enhancement in quaternary III-nitrides alloys grown by\n  molecular beam epitaxy with increasing Al content: Room temperature photoluminescence and optical absorption spectra have been\nmeasured in wurtzite In$_{x}$Al$_{y}$Ga$_{1-x-y}$N (x $\\approx$ 0.06, 0.02 < y\n< 0.27) layers grown by molecular beam epitaxy. Photoluminescence spectra show\nboth an enhancement of the integrated intensity and an increasing Stokes shift\nwith the Al content. Both effects arise from an Al-enhanced exciton\nlocalization revealed by the S- and W-shaped temperature dependences of the\nphotoluminescence emission energy and bandwidth respectively. Present results\npoint to these materials as a promising choice for the active region in\nefficient light emitters. An In-related bowing parameter of 1.6 eV was derived\nfrom optical absorption data."
    },
    {
        "anchor": "NMR and NQR parameters of ethanol crystal: Electric field gradients and chemical shielding tensors of the stable\nmonoclinic crystal phase of ethanol are computed. The projector-augmented wave\n(PAW) and gauge-including projector-augmented wave (GIPAW) models in the\nperiodic plane-wave density functional theory are used. The crystal data from\nX-ray measurements, as well as the structures where either all atomic, or only\nhydrogen atom positions are optimized in the density functional theory are\nanalyzed. These structural models are also studied by including the\nsemi-empirical Van der Waals correction to the density functional theory.\nInfrared spectra of these five crystal models are calculated.",
        "positive": "Multi-Orbital Molecular Compound (TTM-TTP)I_3: Effective Model and\n  Fragment Decomposition: The electronic structure of the molecular compound (TTM-TTP)I_3, which\nexhibits a peculiar intra-molecular charge ordering, has been studied using\nmulti-configuration ab initio calculations. First we derive an effective\nHubbard-type model based on the molecular orbitals (MOs) of TTM-TTP; we set up\na two-orbital Hamiltonian for the two MOs near the Fermi energy and determine\nits full parameters: the transfer integrals, the Coulomb and exchange\ninteractions. The tight-binding band structure obtained from these transfer\nintegrals is consistent with the result of the direct band calculation based on\ndensity functional theory. Then, by decomposing the frontier MOs into two\nparts, i.e., fragments, we find that the stacked TTM-TTP molecules can be\ndescribed by a two-leg ladder model, while the inter-fragment Coulomb energies\nare scaled to the inverse of their distances. This result indicates that the\nfragment picture that we proposed earlier [M.-L. Bonnet et al.: J. Chem. Phys.\n132 (2010) 214705] successfully describes the low-energy properties of this\ncompound."
    },
    {
        "anchor": "Gilbert Damping in Magnetic Multilayers: We study the enhancement of the ferromagnetic relaxation rate in thin films\ndue to the adjacent normal metal layers. Using linear response theory, we\nderive the dissipative torque produced by the s-d exchange interaction at the\nferromagnet-normal metal interface. For a slow precession, the enhancement of\nGilbert damping constant is proportional to the square of the s-d exchange\nconstant times the zero-frequency limit of the frequency derivative of the\nlocal dynamic spin susceptibility of the normal metal at the interface.\nElectron-electron interactions increase the relaxation rate by the Stoner\nfactor squared. We attribute the large anisotropic enhancements of the\nrelaxation rate observed recently in multilayers containing palladium to this\nmechanism. For free electrons, the present theory compares favorably with\nrecent spin-pumping result of Tserkovnyak et al. [Phys. Rev. Lett.\n\\textbf{88},117601 (2002)].",
        "positive": "Comparison of Process of Diffusion of Interstitial Oxygen Atoms and\n  Interstitial Hydrogen Molecules in Silicon and Germanium Crystals:\n  Quantumchemical Simulation: The theoretical analysis of the process of diffusion of interstitial oxygen\natoms and hydrogen molecules in silicon and germanium crystals has been\nperformed. The calculated values of the activation energy and pre-exponential\nfactor for an interstitial oxygen atom Ea(Si) = 2.59 eV, Ea(Ge) = 2.05 eV,\nD(Si)= 0.28 cm2s-1, D(Ge)= 0.39 cm2s-1 and interstitial hydrogen molecule\nEa(Si) = 0.79-0.83 eV, Ea(Ge) = 0.58-0.62 eV, D(Si)= 7.4 10(-4) cm2s-1, D(Ge)=\n6.5 10(-4) cm2s-1 are in an excellent agreement with experimental ones and for\nthe first time describe perfectly an experimental temperature dependence of an\ninterstitial oxygen atom and hydrogen molecules diffusion constant in Si and Ge\ncrystals. It is shown, that for a case of impurity atom with a strong\ninteraction with a lattice (interstitial oxygen atom) process of diffusion has\na cooperative nature - the activation energy and pre-exponential are controlled\nby the optimum position of three nearest lattice atoms. For a case of extended\ndefect with a weak interaction (an interstitial hydrogen molecule) process of\ndiffusion is determined by the activation barrier subjected to fluctuations\nconnected with rotation of a hydrogen molecule. The effect of hydrostatic\npressure on the process of diffusion is discussed also."
    }
]